Helicobacter pylori and autoimmune disease: Cause or bystander

Table 3 Evidence in support or against the role of Helicobacter pylori in autoimmune disease

Autoimmune condition	Evidence in support and/or against the role of H. pylori	Overall opinion
SjS	Support:	Inconclusive
	Oral cavity populated with H. pylori
	Higher level of anti-H. pylori antibodies in SjS patients
	Increased incidence of mucosal associated lymphoid tissue and lymphomas in parotid and lacrimal glands of SjS patients
	Against:
	Low levels of anti-H. pylori antibodies in SjS patients compared to controls
SSc	Support:	Inconclusive
	Higher incidence of H. pylori antibodies in SSc patients than controls
	H. pylori eradication improves Raynaud's in SSc patients
	Possible protective role against Barrett's esophagus
	Higher level of CagA strain H. pylori infected patients
	Against:
	Low incidence of anti-H. pylori antibodies compared to controls
RA	Support:	Unlikely
	Increased rheumatoid factor IgM from B cells chronically stimulated with H. pylori urease
	Against:
	Low prevalence of anti-H. pylori in RA patients
	Unchanged clinical course or symptomatology after H. pylori eradication
SLE	Support:	Unlikely
	H. pylori urease exposure induced anti-ssDNA antibody production in an animal model of SLE
	Against:
	Low levels of anti-H. pylori found among SLE patients, at levels comparable to controls
	Negative association between H. pylori seropositivity and the development of SLE in African-American women
ITP	Support:	Probable
	Improvement of platelet counts following H. pylori eradication (CagA type H. pylori in particular)
	Anti-CagA antibodies cross-react with peptides on platelets of ITP patient
	Platelet associated IgGs declined following H. pylori eradication
	Found in high prevalence in some ITP cohorts
	Platelet eluates from ITP patients recognize H. pylori CagA
	Against:
	Low levels of H. pylori found in ITP patients
AiTD	Support:	Probable in Graves’ disease
	Higher seropositivity and positive stool cultures for H. pylori in Graves’ disease patients
	CagA strain predominant among Graves’ disease patients
	Amino acid similarities between CagA and thyroid peroxidase
	Reduction in anti-thyroid antibodies following H. pylori eradication
	Against:	Unlikely in Hashimoto’s thyroiditis
	Low levels of infection among Hashimoto’s thyroiditis patients
MS and NMO	Support:	Probable in NMO
	High rate of H. pylori infection among NMO patients
	Correlation between H. pylori infection and presence of aquaporin-4 antibodies
	Against:	Unlikely in MS
	H. pylori infection rates in MS patients similar to or lower than control groups
Psoriasis	Support:	Probable
	Higher levels of anti-H. pylori antibodies in patients
	Appears to be correlation between H. pylori infection and disease severity
	Clinical improvement following H. pylori eradication
	Against:
	No difference in anti-H. pylori levels compared to controls
	No difference of CagA seropositivity between patients and controls
Behçet’s disease	Support:	Unlikely
	Higher infection prevalence in patients
	Some clinical improvement noted after eradication
	Against:
	No difference between patients and controls
Alopecia areata	Support:	Unlikely
	Higher infection prevalence
	Against:
	No difference in infection prevalence between patients and controls
PBC	Support:	Unlikely
	Higher prevalence of anti-H. pylori antibodies among PBC patients
	Amino acid similarities between pyruvate dehydrogenase E2 (PDC-E2) and urease beta of H. pylori
	Against:
	No differences of infection found between patients and controls
	No immunological cross reactivities at the B or CD4 T-cell level
	No crossreactivity between H. pylori VacA and PDC-E2
AIH	Support:	Unlikely
	No current evidence
	Against:
	No differences in anti-H. pylori antibodies between patients and controls
	No significant difference between H. pylori in liver tissues in patients compared to controls
PSC	Support:	Unlikely
	Detectable H. pylori DNA in PSC liver samples
	CagA in samples from PSC patients
	Concomitant ulcerative colitis may be related to H. pylori translocation from the gut to the liver
	Against:
	No difference in H. pylori prevalence among pediatric or adult PSC patients compared to controls
	No significant difference between H. pylori in liver tissues in patients compared to controls

Helicobacter pylori (H. pylori) has been implicated in the development of several autoimmune diseases. This table summarizes some of the evidence in support or against this hypothesis in various autoimmune diseases. Overall opinions reflect an inconclusive evidence base, those which are unlikely, and those which have a relatively strong or strong (probable) evidence base. SjS: Sjogren’s syndrome; SSc: Systemic sclerosis; RA: Rheumatoid arthritis; SLE: Systemic lupus erythematosus; ITP: Immune thrombocytopenic purpura; AiTD: Autoimmune thyroid disease; MS: Multiple Sclerosis; NMO: Neuromyelitis optica; PBC: Primary biliary cirrhosis; AIH: Autoimmune hepatitis; PSC: Primary sclerosing cholangitis.