Helicobacter pylori infection pathophysiology: Difference between revisions

Jump to navigation Jump to search
VisualWikitext
No edit summary
 
(166 intermediate revisions by the same user not shown)
Line 4: Line 4:


==Overview==
==Overview==
Helicobacter pylori (H. pylori) is a bacterium that lives on the lining of the stomach. Although we used to think that spicy food, acid, and stress were the major causes of ulcers, we now know that nine out of ten ulcers are caused by H. pylori. Medicines that reduce stomach acid may make you feel better, but your ulcer may come back. Here's the good news: Since most ulcers are caused by this bacterial infection, they can be cured with the right antibiotics.
Person to person [[transmission]] is considered to be the most likely route of transmission of ''[[Helicobacter pylori]]''. ''[[H. pylori]]'' is a noninvasive organism. It is found over [[mucus]] secreting cells but not in deeper [[gastric glands]]. Hence it can only inhabit gastric-type mucus but cannot colonize the [[esophagus]] or [[duodenum]]. Pathogenesis of ''[[H. pylori]]'' infection depends on bacterial, host and environmental factors.


==Pathophysiology==
==Pathophysiology==
*The mode of transmission of H.pylori is poorly understood.<ref name="pmid11218379">{{cite journal| author=Brown LM| title=Helicobacter pylori: epidemiology and routes of transmission. | journal=Epidemiol Rev | year= 2000 | volume= 22 | issue= 2 | pages= 283-97 | pmid=11218379 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11218379  }} </ref><ref name="pmid9394753">{{cite journal| author=Cave DR| title=How is Helicobacter pylori transmitted? | journal=Gastroenterology | year= 1997 | volume= 113 | issue= 6 Suppl | pages= S9-14 | pmid=9394753 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9394753  }} </ref><ref name=H.pylori>Transmission http://www.who.int/bulletin/archives/79(5)455.pdf (2001) Accessed on December 27, 2016</ref>
*The mode of [[transmission]] of ''[[H. pylori]]'' is poorly understood.<ref name="pmid11218379">{{cite journal| author=Brown LM| title=Helicobacter pylori: epidemiology and routes of transmission. | journal=Epidemiol Rev | year= 2000 | volume= 22 | issue= 2 | pages= 283-97 | pmid=11218379 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11218379  }} </ref><ref name="pmid9394753">{{cite journal| author=Cave DR| title=How is Helicobacter pylori transmitted? | journal=Gastroenterology | year= 1997 | volume= 113 | issue= 6 Suppl | pages= S9-14 | pmid=9394753 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9394753  }} </ref><ref name=H.pylori>Transmission http://www.who.int/bulletin/archives/79(5)455.pdf (2001) Accessed on December 27, 2016</ref>
*Person to person transmission is considered to be the most likely route.  
*Person to person [[transmission]] is considered to be the most likely route.  
*Helicobacter pylori is usually transmitted via the following routes:
*It is almost always acquired during childhood and [[infection]] is lifelong if left untreated.<ref name="pmid17401270">{{cite journal| author=Das JC, Paul N| title=Epidemiology and pathophysiology of Helicobacter pylori infection in children. | journal=Indian J Pediatr | year= 2007 | volume= 74 | issue= 3 | pages= 287-90 | pmid=17401270 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17401270  }} </ref>
*''[[Helicobacter pylori]]'' is usually transmitted via the following routes:


:*Iatrogenic  
:*'''Iatrogenic'''
::*Via tubes and endoscopes that have been in contact with the gastric mucosa of one individual are used for another patient
::*Via tubes and endoscopes that have been in contact with the [[gastric mucosa]] of one individual are used for another patient
::*Between patient and staff especially among endoscopists and gastroenterologists
::*Between patient and staff especially among endoscopists and gastroenterologists
:*Fecal-oral route
:*'''Fecal-oral route'''
::*Fecal contamination of water and food may be the source of infection
::*[[Feces|Fecal]] contamination of water and food may be the source of [[infection]] especially in developing countries<ref name="pmid17401270">{{cite journal| author=Das JC, Paul N| title=Epidemiology and pathophysiology of Helicobacter pylori infection in children. | journal=Indian J Pediatr | year= 2007 | volume= 74 | issue= 3 | pages= 287-90 | pmid=17401270 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17401270  }} </ref>
:*Oral-oral route  
:*'''Oral-oral route'''
::*Via saliva
::*Via [[saliva]] especially in developed countries<ref name="pmid17401270">{{cite journal| author=Das JC, Paul N| title=Epidemiology and pathophysiology of Helicobacter pylori infection in children. | journal=Indian J Pediatr | year= 2007 | volume= 74 | issue= 3 | pages= 287-90 | pmid=17401270 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17401270  }} </ref>
*[[Adenocarcinoma|Distal adenocarcinoma]] is the most common [[gastric adenocarcinoma]] which is caused by ''[[H. pylori]]''.
*The colonization of ''[[H. pylori]]'' in [[gastric mucosa]] depends on the following factors:
:*Motility of ''[[H. pylori]]'' (The corkscrew motility is due to its multiple [[flagella]] and spiral shape)
:*[[Chemotaxis]]
:*Environmental sensing
:*Acid resistance
:*Iron acquisition
*''[[H. pylori]]'' primarily colonizes in [[gastric mucosa]] but occasionally found at other sites also. The few of the sites include [[eyes]], [[nasal cavity]], [[gallbladder]], [[peritoneum]], and [[oral cavity]].


'''Pathogenesis'''
==Pathogenesis==
*The pathogenesis of H.pylori depends up on the following:
*The pathogenesis involves four important steps. They are:
:*Strain virulence
:*Adhesion of ''[[H. pylori]]'' to host cell
:*Host genetic susceptibility
:*Decreasing the [[gastric acid]] content of [[stomach]]
:*Environmental co factors
:*Colonization
:*[[Inflammation]]


Following transmission, the H.pylori can directly injure gastric epithelial cells by the secretion of enzymes and by the elaboration of toxins.<ref name="pmid9394757">{{cite journal| author=Smoot DT| title=How does Helicobacter pylori cause mucosal damage? Direct mechanisms. | journal=Gastroenterology | year= 1997 | volume= 113 | issue= 6 Suppl | pages= S31-4; discussion S50 | pmid=9394757 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9394757  }} </ref><ref name="pmid12520704">{{cite journal| author=Jhala NC, Siegal GP, Klemm K, Atkinson BF, Jhala DN| title=Infiltration of Helicobacter pylori in the gastric mucosa. | journal=Am J Clin Pathol | year= 2003 | volume= 119 | issue= 1 | pages= 101-7 | pmid=12520704 | doi=10.1309/YDTX-KE06-XHTH-FNP2 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12520704 }} </ref>
*Based on the location of [[inflammation]], the [[pathogenesis]] depends on:<ref name="pmid18039108">{{cite journal| author=Atherton JC| title=The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases. | journal=Annu Rev Pathol | year= 2006 | volume= 1 | issue= | pages= 63-96 | pmid=18039108 | doi=10.1146/annurev.pathol.1.110304.100125 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18039108 }} </ref>
:* Antral-predominant inflammation: The uninflamed corpus produces large amount of acid predisposing to [[duodenal ulceration]]
:*Corpus-predominant inflammation: This leads to [[gastric ulcer|gastric ulceration]] and [[adenocarcinoma]] due to [[hypochlorhydria]]


For further information on pathogenesis please click [[Helicobacter pylori infection pathophysiology#Pathogenesis of H.pylori Infection|here]]


===Factors Associated With Pathogenesis===
*''[[H. pylori]]'' is a non invasive organism. It is found over [[mucus]] secreting cells but not in deeper [[gastric glands]]. Hence it can only inhabit [[gastric mucosa|gastric-type mucus]] but cannot colonize the [[esophagus]] or [[duodenum]]. <ref name="pmid12520704">{{cite journal| author=Jhala NC, Siegal GP, Klemm K, Atkinson BF, Jhala DN| title=Infiltration of Helicobacter pylori in the gastric mucosa. | journal=Am J Clin Pathol | year= 2003 | volume= 119 | issue= 1 | pages= 101-7 | pmid=12520704 | doi=10.1309/YDTX-KE06-XHTH-FNP2 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12520704  }} </ref>. The [[pathogenesis]] of ''[[H. pylori]]'' depends up on the following:<ref name="pmid18039108">{{cite journal| author=Atherton JC| title=The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases. | journal=Annu Rev Pathol | year= 2006 | volume= 1 | issue=  | pages= 63-96 | pmid=18039108 | doi=10.1146/annurev.pathol.1.110304.100125 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18039108  }} </ref>
{| class="wikitable"
! colspan="3" |Factors Associated With H. pylori Pathogenesis
|-
!Bacterial
!Host
!Environmental
|-
|[[Flagella]]
| rowspan="2" |Immune response to ''[[H. pylori]]''
* [[Innate immunity]]
* [[Acquired immunity]]
| rowspan="4" |
* Age at [[infection]]
* [[Smoking]]
* Degree of crowding
* [[Malnutrition]]
* High salt intake
* [[Vitamin deficiency]]
|-
| rowspan="2" |[[Bacterial enzymes]]
* [[Lipase]] and [[protease]]
* [[Urease]]
|-
| rowspan="2" |[[Hormone|Hormonal]] and acid [[homeostasis]] changes
* Decrease [[somatostatin]] levels
* Hypergastrinemia
|-
|[[Bacterial Virulence factors]]
* CagA
* Outer inflammatory protein A (OipA)
* Duodenal ulcer promoting gene A (dupA)
* Blood group antigen binding adhesion A (BabA)
* RNA polymerase β-subunit (RpoB)
* Vacuolating cytotoxin (VacA)
|}
===='''1: Bacterial factors'''====
'''A. Flagella'''


The pathophysiology of helicobacter pylori infection
''[[H. pylori]]'' propels through the [[mucus layer]] with the help of [[flagella]] and adheres to the gastric [[epithelial cells]] through [[fimbriae]] which are the extension of [[bacterial cytoplasm]].
* Helicobacter pylori (H. pylori) is a spiral-shaped bacterium that is found in the gastric mucous layer or adherent to the epithelial lining of the [[stomach]]. H. pylori causes more than 90% of [[duodenal ulcer]]s and up to 80% of [[gastric ulcer]]s.
* Before 1982, when this bacterium was discovered, spicy food, acid, stress, and lifestyle were considered the major causes of ulcers.
* The majority of patients were given long-term medications, such as [[H2 blockers]], and more recently, [[proton pump inhibitors]], without a chance for permanent cure. These medications relieve ulcer-related symptoms, heal gastric mucosal [[inflammation]], and may heal the [[ulcer]], but they do not treat the infection.
* When acid suppression is removed, the majority of ulcers, particularly those caused by H. pylori, recur.
* Since we now know that most [[ulcer]]s are caused by H. pylori, appropriate antibiotic regimens can successfully eradicate the infection in most patients, with complete resolution of mucosal inflammation and a minimal chance for recurrence of [[ulcer]]s.


===Peptic Ulcer Disease from H. Pylori===
'''B. Bacterial enzymes'''
A peptic ulcer is a sore or hole in the lining of the stomach or duodenum (the first part of the small intestine). People of any age can get an ulcer and women are affected just as often as men. Over 25 million Americans will suffer from an ulcer at some point during their lifetime. The good news is that most ulcers are caused by an infection with the bacterium, Helicobacter pylori , and can be cured in about two weeks with antibiotics.  


* Most ulcers are caused by an infection, not spicy food, acid or stress.   
The bacterial [[enzymes]] associated with pathogenesis of ''[[H. pylori]]'' infection include:<ref name="pmid9394757">{{cite journal| author=Smoot DT| title=How does Helicobacter pylori cause mucosal damage? Direct mechanisms. | journal=Gastroenterology | year= 1997 | volume= 113 | issue= 6 Suppl | pages= S31-4; discussion S50 | pmid=9394757 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9394757  }} </ref>
* The most common ulcer symptom is burning pain in the stomach.  
:*[[Lipase]] and [[protease]]
* Your doctor can test you for H. pylori infection.  
::*[[Lipase]] and [[protease]] leads to degradation of protective [[mucous]] layer of the [[stomach]]
* Antibiotics are the new cure for ulcers.  
::*[[Protease]] leads to disintegration of the polymeric structure of [[mucin]]
* Eliminating H. pylori infections with antibiotics means that your ulcer can be cured for good.
::*[[Phospholipase A2]] and [[lipase]] leads to loss of mucosal surface [[hydrophobicity]], mucus lipid degradation, and [[phospholipid|lysophospholipid]] generation<ref name="pmid8038348">{{cite journal| author=Berstad K, Sjödahl R, Berstad A| title=Phospholipase A2 activity in gastric juice from patients with active and H. pylori-eradicated healed duodenal ulcer. | journal=Aliment Pharmacol Ther | year= 1994 | volume= 8 | issue= 2 | pages= 175-80 | pmid=8038348 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8038348  }} </ref><ref name="pmid8253346">{{cite journal| author=Mauch F, Bode G, Ditschuneit H, Malfertheiner P| title=Demonstration of a phospholipid-rich zone in the human gastric epithelium damaged by Helicobacter pylori. | journal=Gastroenterology | year= 1993 | volume= 105 | issue= 6 | pages= 1698-704 | pmid=8253346 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8253346  }} </ref>
::*[[Phospholipid|Lysophospholipids]] disrupts the [[phospholipid ]]rich layer at the apical surface of [[mucous]] cells
:*[[Urease]]
::*Gastric acid resistance plays a crucial role in pathogenesis of '''[[H.pylori]]''' infection.<ref name="pmid14500513">{{cite journal| author=Wen Y, Marcus EA, Matrubutham U, Gleeson MA, Scott DR, Sachs G| title=Acid-adaptive genes of Helicobacter pylori. | journal=Infect Immun | year= 2003 | volume= 71 | issue= 10 | pages= 5921-39 | pmid=14500513 | doi= | pmc=201084 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14500513  }} </ref><ref name="pmid12787351">{{cite journal| author=McGowan CC, Necheva AS, Forsyth MH, Cover TL, Blaser MJ| title=Promoter analysis of Helicobacter pylori genes with enhanced expression at low pH. | journal=Mol Microbiol | year= 2003 | volume= 48 | issue= 5 | pages= 1225-39 | pmid=12787351 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12787351  }} </ref>
::*[[Urease]] is one of the most abundant [[protein]] produced by '''[[H.pyloi]]''', whose production is regulated by one of the [[genes]] associated with gastric acid resistance
::*The [[urease]] of '''[[H.pylori]]''' has two subunits, UreA and UreB.<ref name="pmid2341188">
{{cite journal| author=Smoot DT, Mobley HL, Chippendale GR, Lewison JF, Resau JH| title=Helicobacter pylori urease activity is toxic to human gastric epithelial cells. | journal=Infect Immun | year= 1990 | volume= 58 | issue= 6 | pages= 1992-4 | pmid=2341188 | doi= | pmc=258755 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=2341188  }} </ref><ref name="pmid8463418">{{cite journal| author=Micots I, Augeron C, Laboisse CL, Muzeau F, Mégraud F| title=Mucin exocytosis: a major target for Helicobacter pylori. | journal=J Clin Pathol | year= 1993 | volume= 46 | issue= 3 | pages= 241-5 | pmid=8463418 | doi= | pmc=501178 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8463418  }} </ref>
::*This [[enzyme]] [[hydrolyzes]] [[urea]] to [[ammonia]] and [[carbon dioxide]], which increases the [[cytoplasm|cytoplasmic]] [[pH]] in the micro environment around the organism, hence protects the [[bacteria]] from gastric acid
::*The H+-gated urea channel(Urel) regulates the [[urea]] entry into [[cytoplasm]] of ''[[H. pylori]]'' cell which helps in quick adaptation of organism to acidic environment.<ref name="pmid10642549">{{cite journal| author=Weeks DL, Eskandari S, Scott DR, Sachs G| title=A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization. | journal=Science | year= 2000 | volume= 287 | issue= 5452 | pages= 482-5 | pmid=10642549 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10642549  }} </ref>
::*[[Ammonia]] and [[ammonium chloride]] inhibit the growth of [[gastric cells]] in [[S phase]], leading to gastric mucosal [[atrophy]]<ref name="pmid8574744">{{cite journal| author=Matsui T, Matsukawa Y, Sakai T, Nakamura K, Aoike A, Kawai K| title=Effect of ammonia on cell-cycle progression of human gastric cancer cells. | journal=Eur J Gastroenterol Hepatol | year= 1995 | volume= 7 Suppl 1 | issue=  | pages= S79-81 | pmid=8574744 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8574744  }} </ref>
 
'''C. Bacterial Virulence factors'''
 
The cytotoxin-associated gene (Cag) pathogenecity island (PAI) and cytotoxin-associated gene A (cagA)
*Large amounts of the pro-inflammatory [[Interleukin|cytokine interleukin-8]] are expressed in ''[[H. pylori]]'' strains with CagPaI.
*The protein CagA is encoded by CagA gene and type IV bacterial secretion system (T4SS) is encoded by CagPAI.
*Type IV bacterial secretion apparatus helps in translocation of CagA into host target cells and stimulates epithelial cell pro-inflammatory [[cytokine]] expression and gastric inflammation
*CagA undergoes [[phosphorylation]] in host target cells
The following are the bacterial virulence factors associated with ''[[H. pylori]]'' pathogenesis:
 
'''CagA'''
*The CagA protein is encoded by CagA gene and is translocated to epithelial cell [[cytosol]] through type IV bacterial secretion apparatus.
*It is activated by [[phosphorylation]] on [[tyrosine]] residues by host scr kinases.<ref name="pmid11788577">{{cite journal| author=Selbach M, Moese S, Hauck CR, Meyer TF, Backert S| title=Src is the kinase of the Helicobacter pylori CagA protein in vitro and in vivo. | journal=J Biol Chem | year= 2002 | volume= 277 | issue= 9 | pages= 6775-8 | pmid=11788577 | doi=10.1074/jbc.C100754200 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11788577  }} </ref><ref name="pmid11929545">{{cite journal| author=Stein M, Bagnoli F, Halenbeck R, Rappuoli R, Fantl WJ, Covacci A| title=c-Src/Lyn kinases activate Helicobacter pylori CagA through tyrosine phosphorylation of the EPIYA motifs. | journal=Mol Microbiol | year= 2002 | volume= 43 | issue= 4 | pages= 971-80 | pmid=11929545 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11929545  }} </ref>
*After [[phosphorylation]], it interacts with SHP-2 and activates MAP kinase signalling leading to abnormal [[proliferation]] of gastric epithelial cells.
*The CagA protein also binds to Crk proteins leading to disruption of epithelial cell [[tight junctions]] and tissue damage.
*The type and number of CagA [[tyrosine]] [[phosphorylation]] motifs differ in the individual strains.
*Strains having CagA with more phosphorylation motifs cause [[atrophy]] and [[gastric carcinoma]] than strains with fewer motifs.<ref name="pmid15300584">{{cite journal| author=Argent RH, Kidd M, Owen RJ, Thomas RJ, Limb MC, Atherton JC| title=Determinants and consequences of different levels of CagA phosphorylation for clinical isolates of Helicobacter pylori. | journal=Gastroenterology | year= 2004 | volume= 127 | issue= 2 | pages= 514-23 | pmid=15300584 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15300584  }} </ref><ref name="pmid12447739">{{cite journal| author=Azuma T, Yamakawa A, Yamazaki S, Fukuta K, Ohtani M, Ito Y et al.| title=Correlation between variation of the 3' region of the cagA gene in Helicobacter pylori and disease outcome in Japan. | journal=J Infect Dis | year= 2002 | volume= 186 | issue= 11 | pages= 1621-30 | pmid=12447739 | doi=10.1086/345374 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12447739  }} </ref><ref name="pmid9666002">{{cite journal| author=Yamaoka Y, Kodama T, Kashima K, Graham DY, Sepulveda AR| title=Variants of the 3' region of the cagA gene in Helicobacter pylori isolates from patients with different H. pylori-associated diseases. | journal=J Clin Microbiol | year= 1998 | volume= 36 | issue= 8 | pages= 2258-63 | pmid=9666002 | doi= | pmc=105028 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9666002  }} </ref>
*The [[Interleukin|IL-8]] secretion is independent of [[tyrosine]] [[phosphorylation]] of CagA but dependent on the region having [[phosphorylation]] motifs.
 
'''Outer inflammatory protein A (OipA)'''
*OipA strain is associated with [[duodenal ulcer|duodenal ulceration]] and [[gastric cancer]]<ref name="pmid12145793">{{cite journal| author=Yamaoka Y, Kikuchi S, el-Zimaity HM, Gutierrez O, Osato MS, Graham DY| title=Importance of Helicobacter pylori oipA in clinical presentation, gastric inflammation, and mucosal interleukin 8 production. | journal=Gastroenterology | year= 2002 | volume= 123 | issue= 2 | pages= 414-24 | pmid=12145793 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12145793  }} </ref><ref name="pmid16322107">{{cite journal| author=Yamaoka Y, Ojo O, Fujimoto S, Odenbreit S, Haas R, Gutierrez O et al.| title=Helicobacter pylori outer membrane proteins and gastroduodenal disease. | journal=Gut | year= 2006 | volume= 55 | issue= 6 | pages= 775-81 | pmid=16322107 | doi=10.1136/gut.2005.083014 | pmc=1856239 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16322107  }} </ref>
*This [[protein]] is regulated by [[slipped strand mispairing]]<ref name="pmid10852959">{{cite journal| author=Yamaoka Y, Kwon DH, Graham DY| title=A M(r) 34,000 proinflammatory outer membrane protein (oipA) of Helicobacter pylori. | journal=Proc Natl Acad Sci U S A | year= 2000 | volume= 97 | issue= 13 | pages= 7533-8 | pmid=10852959 | doi=10.1073/pnas.130079797 | pmc=16580 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10852959  }} </ref>
 
'''Duodenal ulcer promoting gene A (dupA)'''
 
This gene is associated with [[duodenal ulcer|duodenal ulceration]] but appeared to protect from [[gastric cancer]] in patients from columbia, Japan and South Korea.<ref name="pmid18950522">{{cite journal| author=Zhang Z, Zheng Q, Chen X, Xiao S, Liu W, Lu H| title=The Helicobacter pylori duodenal ulcer promoting gene, dupA in China. | journal=BMC Gastroenterol | year= 2008 | volume= 8 | issue=  | pages= 49 | pmid=18950522 | doi=10.1186/1471-230X-8-49 | pmc=2584642 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18950522  }} </ref>
 
'''Blood group antigen binding adhesion A (BabA)'''
*BabA2 gene encodes the active form of BabA which binds to fucosylated Le antigens which are expressed on [[gastric epithelial cells]].<ref name="pmid9430586">{{cite journal| author=Ilver D, Arnqvist A, Ogren J, Frick IM, Kersulyte D, Incecik ET et al.| title=Helicobacter pylori adhesin binding fucosylated histo-blood group antigens revealed by retagging. | journal=Science | year= 1998 | volume= 279 | issue= 5349 | pages= 373-7 | pmid=9430586 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9430586  }} </ref>
*BabA increases the [[adhesion]] of ''[[H. pylori]]'' to epithelial cells which leading to increased delivery of factors associated with [[inflammation]].
*Active form of BabA is associated with increased association of Cag+ strains with [[gastric cancer]] and [[duodenal ulcer|duodenal ulceration]].<ref name="pmid10535999">{{cite journal| author=Gerhard M, Lehn N, Neumayer N, Borén T, Rad R, Schepp W et al.| title=Clinical relevance of the Helicobacter pylori gene for blood-group antigen-binding adhesin. | journal=Proc Natl Acad Sci U S A | year= 1999 | volume= 96 | issue= 22 | pages= 12778-83 | pmid=10535999 | doi= | pmc=23096 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10535999  }} </ref>
 
'''The RNA polymerase β-subunit (RpoB)'''
*The RpoBThr is associated with increased secretion of [[IL-8]] from MKN45 cells compared to RpoBAla.
*''[[H. pylori]]'' strains possessing RpoBThr is seen in 67.6% of East Asians and hence associated with increased risk of development of more severe gastroduodenal diseases.<ref name="pmid15297492">{{cite journal| author=Lee KH, Cho MJ, Yamaoka Y, Graham DY, Yun YJ, Woo SY et al.| title=Alanine-threonine polymorphism of Helicobacter pylori RpoB is correlated with differential induction of interleukin-8 in MKN45 cells. | journal=J Clin Microbiol | year= 2004 | volume= 42 | issue= 8 | pages= 3518-24 | pmid=15297492 | doi=10.1128/JCM.42.8.3518-3524.2004 | pmc=497570 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15297492  }} </ref>
 
'''The vacuolating cytotoxin (VacA)'''
*VacA is an [[exotoxin]] which is associated with cellular damage rather than pro-inflammatory cytokine release.<ref name="pmid11595638">{{cite journal| author=Papini E, Zoratti M, Cover TL| title=In search of the Helicobacter pylori VacA mechanism of action. | journal=Toxicon | year= 2001 | volume= 39 | issue= 11 | pages= 1757-67 | pmid=11595638 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11595638  }} </ref>
*The active forms of VacA are associated with increased risk of [[gastric carcinoma]]
 
===='''2. Host genetic susceptibility'''====
The risk of [[gastric carcinoma]] increases due  to :<ref name="pmid10746728">{{cite journal| author=El-Omar EM, Carrington M, Chow WH, McColl KE, Bream JH, Young HA et al.| title=Interleukin-1 polymorphisms associated with increased risk of gastric cancer. | journal=Nature | year= 2000 | volume= 404 | issue= 6776 | pages= 398-402 | pmid=10746728 | doi=10.1038/35006081 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10746728  }} </ref><ref name="pmid12891537">{{cite journal| author=Machado JC, Figueiredo C, Canedo P, Pharoah P, Carvalho R, Nabais S et al.| title=A proinflammatory genetic profile increases the risk for chronic atrophic gastritis and gastric carcinoma. | journal=Gastroenterology | year= 2003 | volume= 125 | issue= 2 | pages= 364-71 | pmid=12891537 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12891537  }} </ref>
*The stable polymorphisms of several [[cytokine]] gens
*Increased expression of  [[Interleukin|IL-1β]] or [[Tumor necrosis factor-alpha|tumor necrosis factor-alpha (TNF)α]]
*The reduced expression of the anti-inflammatory cytokine [[Interleukin|IL-10]] due to single [[nucleotide]] polymorphism
 
====A.The immune response to H.Pylori====
'''The innate immune response'''
*''[[H. pylori]] colonization of the [[gastric mucosa]] is associated with [[innate immunity|innate host defense mechanisms]] leading to the expression of pro-inflammatory and anti-bacterial factors.<ref name="pmid14568391">{{cite journal| author=George JT, Boughan PK, Karageorgiou H, Bajaj-Elliott M| title=Host anti-microbial response to Helicobacter pylori infection. | journal=Mol Immunol | year= 2003 | volume= 40 | issue= 7 | pages= 451-6 | pmid=14568391 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14568391  }} </ref><ref name="pmid9257236">{{cite journal| author=Jung HC, Kim JM, Song IS, Kim CY| title=Helicobacter pylori induces an array of pro-inflammatory cytokines in human gastric epithelial cells: quantification of mRNA for interleukin-8, -1 alpha/beta, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant protein-1 and tumour necrosis factor-alpha. | journal=J Gastroenterol Hepatol | year= 1997 | volume= 12 | issue= 7 | pages= 473-80 | pmid=9257236 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9257236  }} </ref>The expression of these factors results in [[gastritis]].
*The severity of the ''[[H. pylori]] disease and [[carcinogenesis|gastric carcinogenesis]] is associated with the [[innate immunity|innate immune response]].
*The [[innate immunity|innate immune mechanisms]] are dependent on the Nod1, which is a [[pattern recognition receptors|pattern recognition receptors (PRR)]] stimulated by cag+ strains.<ref name="pmid15075354">{{cite journal| author=Netea MG, van der Graaf C, Van der Meer JW, Kullberg BJ| title=Toll-like receptors and the host defense against microbial pathogens: bringing specificity to the innate-immune system. | journal=J Leukoc Biol | year= 2004 | volume= 75 | issue= 5 | pages= 749-55 | pmid=15075354 | doi=10.1189/jlb.1103543 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15075354  }} </ref>
*[[Defensins]] are the anti-microbial [[peptides]] which are secreted as a response to ''[[H. pylori]]'' infection. Elevated levels of [[defensin|human β defensin 2 (hBD2)]] and the [[defensin|neutrophil-derived alpha defensins]] are detected in [[gastric juice]] of infected patients.<ref name="pmid15447750">{{cite journal| author=Isomoto H, Mukae H, Ishimoto H, Date Y, Nishi Y, Inoue K et al.| title=Elevated concentrations of alpha-defensins in gastric juice of patients with Helicobacter pylori infection. | journal=Am J Gastroenterol | year= 2004 | volume= 99 | issue= 10 | pages= 1916-23 | pmid=15447750 | doi=10.1111/j.1572-0241.2004.40334.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15447750  }} </ref>
*The infected gastric [[epithelial cells]] have increased expression of hBD2, hBD3, [[angiogenin]], [[adrenomedullin]], and the [[antimicrobial peptide|human cationic antimicrobial peptide 18]] (LL-37).<ref name="pmid14568391">{{cite journal| author=George JT, Boughan PK, Karageorgiou H, Bajaj-Elliott M| title=Host anti-microbial response to Helicobacter pylori infection. | journal=Mol Immunol | year= 2003 | volume= 40 | issue= 7 | pages= 451-6 | pmid=14568391 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14568391  }} </ref>
*Due to high secretion of [[cytokines]] and [[chemokines]] by the gastric [[epithelial cells]], there is increased migration of [[granulocytes]], [[lymphocytes]] and [[monocytes]] leading to severe inflammatory [[pathology]].<ref name="pmid11018139">{{cite journal| author=Ernst PB, Gold BD| title=The disease spectrum of Helicobacter pylori: the immunopathogenesis of gastroduodenal ulcer and gastric cancer. | journal=Annu Rev Microbiol | year= 2000 | volume= 54 | issue=  | pages= 615-40 | pmid=11018139 | doi=10.1146/annurev.micro.54.1.615 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11018139  }} </ref>
*The ''[[H. pylori]]'' after [[phagocytosis]] survive inside the [[phagosome]] and all [[phagosomes]] fuse to become megasomes. This provides a protected intracellular cavity in the [[macrophage]], contributing to the persistence of [[infection]].<ref name="pmid10620610">{{cite journal| author=Allen LA, Schlesinger LS, Kang B| title=Virulent strains of Helicobacter pylori demonstrate delayed phagocytosis and stimulate homotypic phagosome fusion in macrophages. | journal=J Exp Med | year= 2000 | volume= 191 | issue= 1 | pages= 115-28 | pmid=10620610 | doi= | pmc=2195807 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10620610  }} </ref><ref name="pmid16543403">{{cite journal| author=Schwartz JT, Allen LA| title=Role of urease in megasome formation and Helicobacter pylori survival in macrophages. | journal=J Leukoc Biol | year= 2006 | volume= 79 | issue= 6 | pages= 1214-25 | pmid=16543403 | doi=10.1189/jlb.0106030 | pmc=1868427 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16543403  }} </ref>
 
'''The acquired immune response'''
*''[[H. pylori]]'' stimulates the production of mucosal and systemic [[IgA]] and [[IgG]] antibodies which induces local [[inflammation]] and damage by cross reacting with the [[parietal cell]] [[ATPase|H+,K+-ATPase]] and [[antigens]] on gastric [[epithelial cells]].<ref name="pmid8675304">{{cite journal| author=Appelmelk BJ, Simoons-Smit I, Negrini R, Moran AP, Aspinall GO, Forte JG et al.| title=Potential role of molecular mimicry between Helicobacter pylori lipopolysaccharide and host Lewis blood group antigens in autoimmunity. | journal=Infect Immun | year= 1996 | volume= 64 | issue= 6 | pages= 2031-40 | pmid=8675304 | doi= | pmc=174033 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8675304  }} </ref><ref name="pmid14568977">{{cite journal| author=Amedei A, Bergman MP, Appelmelk BJ, Azzurri A, Benagiano M, Tamburini C et al.| title=Molecular mimicry between Helicobacter pylori antigens and H+, K+ --adenosine triphosphatase in human gastric autoimmunity. | journal=J Exp Med | year= 2003 | volume= 198 | issue= 8 | pages= 1147-56 | pmid=14568977 | doi=10.1084/jem.20030530 | pmc=2194239 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14568977 }} </ref>
*The [[T helper cells|T-helper 1 (Th1)]] response in the [[gastric mucosa]] dominates the [[T-cell]] response to ''[[H. pylori]]''. The [[Th1]] cells release type 1 [[cytokines]] [[interferon|(IFNγ)]] which activate [[macrophages]] resulting in secretion of [[cytokines|pro-inflammatory factors]] (TNFα, IL-12 and IL-18) and increase bactericidal activity compared to those activated by [[cytokines|Th2 cytokines]]. The severity of [[gastritis]] depends on the number of [[interferon|IFNγ]]-secreting cells in the infected gastric mucosa.<ref name="pmid9496938">{{cite journal| author=Bamford KB, Fan X, Crowe SE, Leary JF, Gourley WK, Luthra GK et al.| title=Lymphocytes in the human gastric mucosa during Helicobacter pylori have a T helper cell 1 phenotype. | journal=Gastroenterology | year= 1998 | volume= 114 | issue= 3 | pages= 482-92 | pmid=9496938 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9496938  }} </ref><ref name="pmid8993017">{{cite journal| author=D'Elios MM, Manghetti M, De Carli M, Costa F, Baldari CT, Burroni D et al.| title=T helper 1 effector cells specific for Helicobacter pylori in the gastric antrum of patients with peptic ulcer disease. | journal=J Immunol | year= 1997 | volume= 158 | issue= 2 | pages= 962-7 | pmid=8993017 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8993017  }} </ref><ref name="pmid7959191">{{cite journal| author=Fan XJ, Chua A, Shahi CN, McDevitt J, Keeling PW, Kelleher D| title=Gastric T lymphocyte responses to Helicobacter pylori in patients with H pylori colonisation. | journal=Gut | year= 1994 | volume= 35 | issue= 10 | pages= 1379-84 | pmid=7959191 | doi= | pmc=1375009 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7959191  }} </ref><ref name="pmid12121897">{{cite journal| author=Lehmann FS, Terracciano L, Carena I, Baeriswyl C, Drewe J, Tornillo L et al.| title=In situ correlation of cytokine secretion and apoptosis in Helicobacter pylori-associated gastritis. | journal=Am J Physiol Gastrointest Liver Physiol | year= 2002 | volume= 283 | issue= 2 | pages= G481-8 | pmid=12121897 | doi=10.1152/ajpgi.00422.2001 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12121897  }} </ref>
*''[[H. pylori]]'' suppress immune and inflammatory responses by eliciting Treg (T-cell regulatory) responses and thus maintain chronic colonization. They also suppress human memory [[T-cells]] in response to ''[[H. pylori]]'' [[antigens]].<ref name="pmid12654789">{{cite journal| author=Lundgren A, Suri-Payer E, Enarsson K, Svennerholm AM, Lundin BS| title=Helicobacter pylori-specific CD4+ CD25high regulatory T cells suppress memory T-cell responses to H. pylori in infected individuals. | journal=Infect Immun | year= 2003 | volume= 71 | issue= 4 | pages= 1755-62 | pmid=12654789 | doi= | pmc=152046 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12654789  }} </ref>
 
====B. Hormonal changes and acid homeostasis changes====
'''Somatostatin and gastrin changes'''
*The inflammatory mediators produced due to ''[[H. pylori]]'' infection, including [[nitric oxide]] suppress [[somatostatin]] release. The infection is also associated with reduced numbers of somatostatin-producing [[pancreas|D cells]] in the [[stomach]].<ref name="pmid1357347">{{cite journal| author=Moss SF, Legon S, Bishop AE, Polak JM, Calam J| title=Effect of Helicobacter pylori on gastric somatostatin in duodenal ulcer disease. | journal=Lancet | year= 1992 | volume= 340 | issue= 8825 | pages= 930-2 | pmid=1357347 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1357347  }} </ref><ref name="pmid7911115">{{cite journal| author=Odum L, Petersen HD, Andersen IB, Hansen BF, Rehfeld JF| title=Gastrin and somatostatin in Helicobacter pylori infected antral mucosa. | journal=Gut | year= 1994 | volume= 35 | issue= 5 | pages= 615-8 | pmid=7911115 | doi= | pmc=1374743 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7911115  }} </ref><ref name="pmid12145809">{{cite journal| author=Arebi N, Healey ZV, Bliss PW, Ghatei M, Van Noorden S, Playford RJ et al.| title=Nitric oxide regulates the release of somatostatin from cultured gastric rabbit primary D-cells. | journal=Gastroenterology | year= 2002 | volume= 123 | issue= 2 | pages= 566-76 | pmid=12145809 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12145809  }} </ref>
* The [[gastrin]] production from [[G cells]] is increased due to direct stimulatory action of [[cytokines]] and suppression of [[somatostatin]].
*Hypergastrinemia stimulates [[MAP kinase]] which results in up-regulation of the [[COX|cox-2 gene]] which is potentially has potentially [[oncogenesis|pro-oncogenic]] effect. It may also leads to gastric [[atrophy]] by up-regulation of the [[regulatory protein|Reg protein]].<ref name="pmid12239223">{{cite journal| author=Guo YS, Cheng JZ, Jin GF, Gutkind JS, Hellmich MR, Townsend CM| title=Gastrin stimulates cyclooxygenase-2 expression in intestinal epithelial cells through multiple signaling pathways. Evidence for involvement of ERK5 kinase and transactivation of the epidermal growth factor receptor. | journal=J Biol Chem | year= 2002 | volume= 277 | issue= 50 | pages= 48755-63 | pmid=12239223 | doi=10.1074/jbc.M209016200 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12239223  }} </ref><ref name="pmid12239223">{{cite journal| author=Guo YS, Cheng JZ, Jin GF, Gutkind JS, Hellmich MR, Townsend CM| title=Gastrin stimulates cyclooxygenase-2 expression in intestinal epithelial cells through multiple signaling pathways. Evidence for involvement of ERK5 kinase and transactivation of the epidermal growth factor receptor. | journal=J Biol Chem | year= 2002 | volume= 277 | issue= 50 | pages= 48755-63 | pmid=12239223 | doi=10.1074/jbc.M209016200 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12239223  }} </ref>
*Hypergastrinemia leads to excess acid production leading to [[dyspepsia]].
 
===='''3. Environmental cofactors'''====
The environmental co-factors associated with ''[[H. pylori]]'' are:
*Age at [[infection]]
*Degree of crowding
*[[Smoking]]
*[[Malnutrition]]
*High salt intake
*[[Vitamin deficiency]]
 
===Gross pathology===
On [[gross pathology]], ''[[H. pylori]]'' infection is associated with thickened gastric folds and [[erythema]].<ref name=pathology> H.pylori infection https://librepathology.org/wiki/Helicobacter_gastritis (May,2016) Accessed on January 4, 2017 </ref>
 
===Microscopic pathology===
The microscopic pathology depends on the the following stages:<ref name="pmid8625766">{{cite journal| author=Faigel DO, Furth EE, Childs M, Goin J, Metz DC| title=Histological predictors of active Helicobacter pylori infection. | journal=Dig Dis Sci | year= 1996 | volume= 41 | issue= 5 | pages= 937-43 | pmid=8625766 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8625766  }} </ref>
 
'''Acute H.pylori infection'''
*Most of the initial ''[[H. pylori]]'' colonization occur during childhood but new infections may occur in adults occasionally.<ref name="pmid1752479">{{cite journal| author=Sobala GM, Crabtree JE, Dixon MF, Schorah CJ, Taylor JD, Rathbone BJ et al.| title=Acute Helicobacter pylori infection: clinical features, local and systemic immune response, gastric mucosal histology, and gastric juice ascorbic acid concentrations. | journal=Gut | year= 1991 | volume= 32 | issue= 11 | pages= 1415-8 | pmid=1752479 | doi= | pmc=1379180 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1752479  }} </ref><ref name="pmid8563048">{{cite journal| author=Dixon MF| title=Histological responses to Helicobacter pylori infection: gastritis, atrophy and preneoplasia. | journal=Baillieres Clin Gastroenterol | year= 1995 | volume= 9 | issue= 3 | pages= 467-86 | pmid=8563048 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8563048  }} </ref>
*Associated with transient profound gastric [[hypochlorhydria]]
<small>'''Microscopic pathology'''</small>
:*Surface epithelial degeneration
:*Heavy [[neutrophil|neutrophilic]] infiltration in [[lamina propria]] of [[antrum]] and corpus and infiltrating the foveolar and surface epithelium
:*Gradual infiltration of other [[inflammatory cells]], especially [[lymphocytes]]
 
'''Chronic H.pylori infection'''
*Chronic antral predominant inflammation:
:*Associated with increased stimulated acid production leading to [[duodenal ulceration]]
*Chronic corpus-predominant or pangastritis
:*Associated with reduced acid production
:*Predisposes to [[gastric ulcer|gastric ulceration]] and [[gastric adenocarcinoma]]
<small>'''Microscopic pathology'''</small>
*Epithelial degeneration
*[[Neutrophil]] infiltration
*predominantly [[lymphocyte]], [[monocyte]] and/ or [[plasma cell]] infiltration in the superficial [[lamina propria]]
*Glandular [[atrophy]]
*[[Metaplasia|Intestinal metaplasia]]
*[[Lymphoid tissue]] aggregates
 
==Pathogenesis of H.pylori Infection==
{{#ev:youtube|7NIXpTcQGYY}}


==References==
==References==
{{reflist|2}}
{{reflist|2}}
{{WH}}
{{WS}}
[[Category:Disease]]
[[Category:Infectious disease]]
[[Category:Gastroenterology]]

Latest revision as of 03:27, 24 January 2017

Helicobacter pylori infection Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Gastritis
Peptic ulcer disease
Gastric adenocarcinoma
MALT lymphoma

Causes

Differentiating Helicobacter pylori infection from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Guideline Recommendation

ACG guidelines
ESPGHAN and NASPGHAN guidelines

History and Symptoms

Physical Examination

Diagnostic tests

Endoscopic tests
Nonendoscopic tests

Electrocardiogram

X Ray

CT

MRI

Ultrasound

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Helicobacter pylori infection pathophysiology On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Helicobacter pylori infection pathophysiology

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Helicobacter pylori infection pathophysiology

CDC on Helicobacter pylori infection pathophysiology

Helicobacter pylori infection pathophysiology in the news

Blogs on Helicobacter pylori infection pathophysiology

Directions to Hospitals Treating Helicobacter pylori infection

Risk calculators and risk factors for Helicobacter pylori infection pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Yamuna Kondapally, M.B.B.S[2]

Overview

Person to person transmission is considered to be the most likely route of transmission of Helicobacter pylori. H. pylori is a noninvasive organism. It is found over mucus secreting cells but not in deeper gastric glands. Hence it can only inhabit gastric-type mucus but cannot colonize the esophagus or duodenum. Pathogenesis of H. pylori infection depends on bacterial, host and environmental factors.

Pathophysiology

  • Iatrogenic
  • Via tubes and endoscopes that have been in contact with the gastric mucosa of one individual are used for another patient
  • Between patient and staff especially among endoscopists and gastroenterologists
  • Fecal-oral route
  • Fecal contamination of water and food may be the source of infection especially in developing countries[4]
  • Oral-oral route
  • Via saliva especially in developed countries[4]
  • Motility of H. pylori (The corkscrew motility is due to its multiple flagella and spiral shape)
  • Chemotaxis
  • Environmental sensing
  • Acid resistance
  • Iron acquisition

Pathogenesis

  • The pathogenesis involves four important steps. They are:

For further information on pathogenesis please click here

Factors Associated With Pathogenesis

Factors Associated With H. pylori Pathogenesis
Bacterial Host Environmental
Flagella Immune response to H. pylori
Bacterial enzymes
Hormonal and acid homeostasis changes
Bacterial Virulence factors
  • CagA
  • Outer inflammatory protein A (OipA)
  • Duodenal ulcer promoting gene A (dupA)
  • Blood group antigen binding adhesion A (BabA)
  • RNA polymerase β-subunit (RpoB)
  • Vacuolating cytotoxin (VacA)

1: Bacterial factors

A. Flagella

H. pylori propels through the mucus layer with the help of flagella and adheres to the gastric epithelial cells through fimbriae which are the extension of bacterial cytoplasm.

B. Bacterial enzymes

The bacterial enzymes associated with pathogenesis of H. pylori infection include:[7]

C. Bacterial Virulence factors

The cytotoxin-associated gene (Cag) pathogenecity island (PAI) and cytotoxin-associated gene A (cagA)

  • Large amounts of the pro-inflammatory cytokine interleukin-8 are expressed in H. pylori strains with CagPaI.
  • The protein CagA is encoded by CagA gene and type IV bacterial secretion system (T4SS) is encoded by CagPAI.
  • Type IV bacterial secretion apparatus helps in translocation of CagA into host target cells and stimulates epithelial cell pro-inflammatory cytokine expression and gastric inflammation
  • CagA undergoes phosphorylation in host target cells

The following are the bacterial virulence factors associated with H. pylori pathogenesis:

CagA

Outer inflammatory protein A (OipA)

Duodenal ulcer promoting gene A (dupA)

This gene is associated with duodenal ulceration but appeared to protect from gastric cancer in patients from columbia, Japan and South Korea.[24]

Blood group antigen binding adhesion A (BabA)

The RNA polymerase β-subunit (RpoB)

  • The RpoBThr is associated with increased secretion of IL-8 from MKN45 cells compared to RpoBAla.
  • H. pylori strains possessing RpoBThr is seen in 67.6% of East Asians and hence associated with increased risk of development of more severe gastroduodenal diseases.[27]

The vacuolating cytotoxin (VacA)

  • VacA is an exotoxin which is associated with cellular damage rather than pro-inflammatory cytokine release.[28]
  • The active forms of VacA are associated with increased risk of gastric carcinoma

2. Host genetic susceptibility

The risk of gastric carcinoma increases due to :[29][30]

A.The immune response to H.Pylori

The innate immune response

The acquired immune response

B. Hormonal changes and acid homeostasis changes

Somatostatin and gastrin changes

3. Environmental cofactors

The environmental co-factors associated with H. pylori are:

Gross pathology

On gross pathology, H. pylori infection is associated with thickened gastric folds and erythema.[49]

Microscopic pathology

The microscopic pathology depends on the the following stages:[50]

Acute H.pylori infection

  • Most of the initial H. pylori colonization occur during childhood but new infections may occur in adults occasionally.[51][52]
  • Associated with transient profound gastric hypochlorhydria

Microscopic pathology

Chronic H.pylori infection

  • Chronic antral predominant inflammation:
  • Chronic corpus-predominant or pangastritis

Microscopic pathology

Pathogenesis of H.pylori Infection

{{#ev:youtube|7NIXpTcQGYY}}

References

  1. ↑ Brown LM (2000). "Helicobacter pylori: epidemiology and routes of transmission". Epidemiol Rev. 22 (2): 283–97. PMID 11218379.
  2. ↑ Cave DR (1997). "How is Helicobacter pylori transmitted?". Gastroenterology. 113 (6 Suppl): S9–14. PMID 9394753.
  3. ↑ Transmission http://www.who.int/bulletin/archives/79(5)455.pdf (2001) Accessed on December 27, 2016
  4. ↑ 4.0 4.1 4.2 Das JC, Paul N (2007). "Epidemiology and pathophysiology of Helicobacter pylori infection in children". Indian J Pediatr. 74 (3): 287–90. PMID 17401270.
  5. ↑ 5.0 5.1 Atherton JC (2006). "The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases". Annu Rev Pathol. 1: 63–96. doi:10.1146/annurev.pathol.1.110304.100125. PMID 18039108.
  6. ↑ Jhala NC, Siegal GP, Klemm K, Atkinson BF, Jhala DN (2003). "Infiltration of Helicobacter pylori in the gastric mucosa". Am J Clin Pathol. 119 (1): 101–7. doi:10.1309/YDTX-KE06-XHTH-FNP2. PMID 12520704.
  7. ↑ Smoot DT (1997). "How does Helicobacter pylori cause mucosal damage? Direct mechanisms". Gastroenterology. 113 (6 Suppl): S31–4, discussion S50. PMID 9394757.
  8. ↑ Berstad K, Sjödahl R, Berstad A (1994). "Phospholipase A2 activity in gastric juice from patients with active and H. pylori-eradicated healed duodenal ulcer". Aliment Pharmacol Ther. 8 (2): 175–80. PMID 8038348.
  9. ↑ Mauch F, Bode G, Ditschuneit H, Malfertheiner P (1993). "Demonstration of a phospholipid-rich zone in the human gastric epithelium damaged by Helicobacter pylori". Gastroenterology. 105 (6): 1698–704. PMID 8253346.
  10. ↑ Wen Y, Marcus EA, Matrubutham U, Gleeson MA, Scott DR, Sachs G (2003). "Acid-adaptive genes of Helicobacter pylori". Infect Immun. 71 (10): 5921–39. PMC 201084. PMID 14500513.
  11. ↑ McGowan CC, Necheva AS, Forsyth MH, Cover TL, Blaser MJ (2003). "Promoter analysis of Helicobacter pylori genes with enhanced expression at low pH". Mol Microbiol. 48 (5): 1225–39. PMID 12787351.
  12. ↑ Smoot DT, Mobley HL, Chippendale GR, Lewison JF, Resau JH (1990). "Helicobacter pylori urease activity is toxic to human gastric epithelial cells". Infect Immun. 58 (6): 1992–4. PMC 258755. PMID 2341188.
  13. ↑ Micots I, Augeron C, Laboisse CL, Muzeau F, Mégraud F (1993). "Mucin exocytosis: a major target for Helicobacter pylori". J Clin Pathol. 46 (3): 241–5. PMC 501178. PMID 8463418.
  14. ↑ Weeks DL, Eskandari S, Scott DR, Sachs G (2000). "A H+-gated urea channel: the link between Helicobacter pylori urease and gastric colonization". Science. 287 (5452): 482–5. PMID 10642549.
  15. ↑ Matsui T, Matsukawa Y, Sakai T, Nakamura K, Aoike A, Kawai K (1995). "Effect of ammonia on cell-cycle progression of human gastric cancer cells". Eur J Gastroenterol Hepatol. 7 Suppl 1: S79–81. PMID 8574744.
  16. ↑ Selbach M, Moese S, Hauck CR, Meyer TF, Backert S (2002). "Src is the kinase of the Helicobacter pylori CagA protein in vitro and in vivo". J Biol Chem. 277 (9): 6775–8. doi:10.1074/jbc.C100754200. PMID 11788577.
  17. ↑ Stein M, Bagnoli F, Halenbeck R, Rappuoli R, Fantl WJ, Covacci A (2002). "c-Src/Lyn kinases activate Helicobacter pylori CagA through tyrosine phosphorylation of the EPIYA motifs". Mol Microbiol. 43 (4): 971–80. PMID 11929545.
  18. ↑ Argent RH, Kidd M, Owen RJ, Thomas RJ, Limb MC, Atherton JC (2004). "Determinants and consequences of different levels of CagA phosphorylation for clinical isolates of Helicobacter pylori". Gastroenterology. 127 (2): 514–23. PMID 15300584.
  19. ↑ Azuma T, Yamakawa A, Yamazaki S, Fukuta K, Ohtani M, Ito Y; et al. (2002). "Correlation between variation of the 3' region of the cagA gene in Helicobacter pylori and disease outcome in Japan". J Infect Dis. 186 (11): 1621–30. doi:10.1086/345374. PMID 12447739.
  20. ↑ Yamaoka Y, Kodama T, Kashima K, Graham DY, Sepulveda AR (1998). "Variants of the 3' region of the cagA gene in Helicobacter pylori isolates from patients with different H. pylori-associated diseases". J Clin Microbiol. 36 (8): 2258–63. PMC 105028. PMID 9666002.
  21. ↑ Yamaoka Y, Kikuchi S, el-Zimaity HM, Gutierrez O, Osato MS, Graham DY (2002). "Importance of Helicobacter pylori oipA in clinical presentation, gastric inflammation, and mucosal interleukin 8 production". Gastroenterology. 123 (2): 414–24. PMID 12145793.
  22. ↑ Yamaoka Y, Ojo O, Fujimoto S, Odenbreit S, Haas R, Gutierrez O; et al. (2006). "Helicobacter pylori outer membrane proteins and gastroduodenal disease". Gut. 55 (6): 775–81. doi:10.1136/gut.2005.083014. PMC 1856239. PMID 16322107.
  23. ↑ Yamaoka Y, Kwon DH, Graham DY (2000). "A M(r) 34,000 proinflammatory outer membrane protein (oipA) of Helicobacter pylori". Proc Natl Acad Sci U S A. 97 (13): 7533–8. doi:10.1073/pnas.130079797. PMC 16580. PMID 10852959.
  24. ↑ Zhang Z, Zheng Q, Chen X, Xiao S, Liu W, Lu H (2008). "The Helicobacter pylori duodenal ulcer promoting gene, dupA in China". BMC Gastroenterol. 8: 49. doi:10.1186/1471-230X-8-49. PMC 2584642. PMID 18950522.
  25. ↑ Ilver D, Arnqvist A, Ogren J, Frick IM, Kersulyte D, Incecik ET; et al. (1998). "Helicobacter pylori adhesin binding fucosylated histo-blood group antigens revealed by retagging". Science. 279 (5349): 373–7. PMID 9430586.
  26. ↑ Gerhard M, Lehn N, Neumayer N, Borén T, Rad R, Schepp W; et al. (1999). "Clinical relevance of the Helicobacter pylori gene for blood-group antigen-binding adhesin". Proc Natl Acad Sci U S A. 96 (22): 12778–83. PMC 23096. PMID 10535999.
  27. ↑ Lee KH, Cho MJ, Yamaoka Y, Graham DY, Yun YJ, Woo SY; et al. (2004). "Alanine-threonine polymorphism of Helicobacter pylori RpoB is correlated with differential induction of interleukin-8 in MKN45 cells". J Clin Microbiol. 42 (8): 3518–24. doi:10.1128/JCM.42.8.3518-3524.2004. PMC 497570. PMID 15297492.
  28. ↑ Papini E, Zoratti M, Cover TL (2001). "In search of the Helicobacter pylori VacA mechanism of action". Toxicon. 39 (11): 1757–67. PMID 11595638.
  29. ↑ El-Omar EM, Carrington M, Chow WH, McColl KE, Bream JH, Young HA; et al. (2000). "Interleukin-1 polymorphisms associated with increased risk of gastric cancer". Nature. 404 (6776): 398–402. doi:10.1038/35006081. PMID 10746728.
  30. ↑ Machado JC, Figueiredo C, Canedo P, Pharoah P, Carvalho R, Nabais S; et al. (2003). "A proinflammatory genetic profile increases the risk for chronic atrophic gastritis and gastric carcinoma". Gastroenterology. 125 (2): 364–71. PMID 12891537.
  31. ↑ 31.0 31.1 George JT, Boughan PK, Karageorgiou H, Bajaj-Elliott M (2003). "Host anti-microbial response to Helicobacter pylori infection". Mol Immunol. 40 (7): 451–6. PMID 14568391.
  32. ↑ Jung HC, Kim JM, Song IS, Kim CY (1997). "Helicobacter pylori induces an array of pro-inflammatory cytokines in human gastric epithelial cells: quantification of mRNA for interleukin-8, -1 alpha/beta, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant protein-1 and tumour necrosis factor-alpha". J Gastroenterol Hepatol. 12 (7): 473–80. PMID 9257236.
  33. ↑ Netea MG, van der Graaf C, Van der Meer JW, Kullberg BJ (2004). "Toll-like receptors and the host defense against microbial pathogens: bringing specificity to the innate-immune system". J Leukoc Biol. 75 (5): 749–55. doi:10.1189/jlb.1103543. PMID 15075354.
  34. ↑ Isomoto H, Mukae H, Ishimoto H, Date Y, Nishi Y, Inoue K; et al. (2004). "Elevated concentrations of alpha-defensins in gastric juice of patients with Helicobacter pylori infection". Am J Gastroenterol. 99 (10): 1916–23. doi:10.1111/j.1572-0241.2004.40334.x. PMID 15447750.
  35. ↑ Ernst PB, Gold BD (2000). "The disease spectrum of Helicobacter pylori: the immunopathogenesis of gastroduodenal ulcer and gastric cancer". Annu Rev Microbiol. 54: 615–40. doi:10.1146/annurev.micro.54.1.615. PMID 11018139.
  36. ↑ Allen LA, Schlesinger LS, Kang B (2000). "Virulent strains of Helicobacter pylori demonstrate delayed phagocytosis and stimulate homotypic phagosome fusion in macrophages". J Exp Med. 191 (1): 115–28. PMC 2195807. PMID 10620610.
  37. ↑ Schwartz JT, Allen LA (2006). "Role of urease in megasome formation and Helicobacter pylori survival in macrophages". J Leukoc Biol. 79 (6): 1214–25. doi:10.1189/jlb.0106030. PMC 1868427. PMID 16543403.
  38. ↑ Appelmelk BJ, Simoons-Smit I, Negrini R, Moran AP, Aspinall GO, Forte JG; et al. (1996). "Potential role of molecular mimicry between Helicobacter pylori lipopolysaccharide and host Lewis blood group antigens in autoimmunity". Infect Immun. 64 (6): 2031–40. PMC 174033. PMID 8675304.
  39. ↑ Amedei A, Bergman MP, Appelmelk BJ, Azzurri A, Benagiano M, Tamburini C; et al. (2003). "Molecular mimicry between Helicobacter pylori antigens and H+, K+ --adenosine triphosphatase in human gastric autoimmunity". J Exp Med. 198 (8): 1147–56. doi:10.1084/jem.20030530. PMC 2194239. PMID 14568977.
  40. ↑ Bamford KB, Fan X, Crowe SE, Leary JF, Gourley WK, Luthra GK; et al. (1998). "Lymphocytes in the human gastric mucosa during Helicobacter pylori have a T helper cell 1 phenotype". Gastroenterology. 114 (3): 482–92. PMID 9496938.
  41. ↑ D'Elios MM, Manghetti M, De Carli M, Costa F, Baldari CT, Burroni D; et al. (1997). "T helper 1 effector cells specific for Helicobacter pylori in the gastric antrum of patients with peptic ulcer disease". J Immunol. 158 (2): 962–7. PMID 8993017.
  42. ↑ Fan XJ, Chua A, Shahi CN, McDevitt J, Keeling PW, Kelleher D (1994). "Gastric T lymphocyte responses to Helicobacter pylori in patients with H pylori colonisation". Gut. 35 (10): 1379–84. PMC 1375009. PMID 7959191.
  43. ↑ Lehmann FS, Terracciano L, Carena I, Baeriswyl C, Drewe J, Tornillo L; et al. (2002). "In situ correlation of cytokine secretion and apoptosis in Helicobacter pylori-associated gastritis". Am J Physiol Gastrointest Liver Physiol. 283 (2): G481–8. doi:10.1152/ajpgi.00422.2001. PMID 12121897.
  44. ↑ Lundgren A, Suri-Payer E, Enarsson K, Svennerholm AM, Lundin BS (2003). "Helicobacter pylori-specific CD4+ CD25high regulatory T cells suppress memory T-cell responses to H. pylori in infected individuals". Infect Immun. 71 (4): 1755–62. PMC 152046. PMID 12654789.
  45. ↑ Moss SF, Legon S, Bishop AE, Polak JM, Calam J (1992). "Effect of Helicobacter pylori on gastric somatostatin in duodenal ulcer disease". Lancet. 340 (8825): 930–2. PMID 1357347.
  46. ↑ Odum L, Petersen HD, Andersen IB, Hansen BF, Rehfeld JF (1994). "Gastrin and somatostatin in Helicobacter pylori infected antral mucosa". Gut. 35 (5): 615–8. PMC 1374743. PMID 7911115.
  47. ↑ Arebi N, Healey ZV, Bliss PW, Ghatei M, Van Noorden S, Playford RJ; et al. (2002). "Nitric oxide regulates the release of somatostatin from cultured gastric rabbit primary D-cells". Gastroenterology. 123 (2): 566–76. PMID 12145809.
  48. ↑ 48.0 48.1 Guo YS, Cheng JZ, Jin GF, Gutkind JS, Hellmich MR, Townsend CM (2002). "Gastrin stimulates cyclooxygenase-2 expression in intestinal epithelial cells through multiple signaling pathways. Evidence for involvement of ERK5 kinase and transactivation of the epidermal growth factor receptor". J Biol Chem. 277 (50): 48755–63. doi:10.1074/jbc.M209016200. PMID 12239223.
  49. ↑ H.pylori infection https://librepathology.org/wiki/Helicobacter_gastritis (May,2016) Accessed on January 4, 2017
  50. ↑ Faigel DO, Furth EE, Childs M, Goin J, Metz DC (1996). "Histological predictors of active Helicobacter pylori infection". Dig Dis Sci. 41 (5): 937–43. PMID 8625766.
  51. ↑ Sobala GM, Crabtree JE, Dixon MF, Schorah CJ, Taylor JD, Rathbone BJ; et al. (1991). "Acute Helicobacter pylori infection: clinical features, local and systemic immune response, gastric mucosal histology, and gastric juice ascorbic acid concentrations". Gut. 32 (11): 1415–8. PMC 1379180. PMID 1752479.
  52. ↑ Dixon MF (1995). "Histological responses to Helicobacter pylori infection: gastritis, atrophy and preneoplasia". Baillieres Clin Gastroenterol. 9 (3): 467–86. PMID 8563048.
Retrieved from "https://www.wikidoc.org/index.php?title=Helicobacter_pylori_infection_pathophysiology&oldid=1285855"