The role of endotoxin in infection: Helicobacter pylori and Campylobacter jejuni

Autor(es): Moran Anthony P

Resumo: Both Helicobacter pylori and Campylobacter jejuni are highly prevalent Gram-negative microaerophilic bacteria which are gastrointestinal pathogens of humans; H. pylori colonizes the gastroduodenal compartment and C. jejuni the intestinal mucosa. Although H. pylori causes chronic gastric infection leading to gastritis, peptic ulcers and eventually gastric cancer while C. jejuni causes acute infection inducing diarrhoeal disease, the endotoxin molecules of both bacterial species contrastingly contribute to their pathogenesis and the autoimmune sequelae each induces. Compared with enterobacterial endotoxin, that of H. pylori has significantly lower endotoxic and immuno-activities, the molecular basis for which is the underphosphorylation and underacylation of the lipid A component that interacts with immune receptors. This induction of low immunological responsiveness by endotoxin may aid the prolongation of H. pylori infection and therefore infection chronicity. On the other hand, this contrasts with acute infection-causing C. jejuni where overt inflammation contributes to pathology and diarrhoea production, and whose endotoxin is immunologically and endotoxically active. Futhermore, both H. pylori and C. jejuni exhibit molecular mimicry in the saccharide components of their endotoxins which can induce autoreactive antibodies; H. pylori expresses mimicry of Lewis and some ABO blood group antigens, C. jejuni mimicry of gangliosides. The former has been implicated in influencing the development of inflammation and gastric atrophy (a precursor of gastic cancer), the latter is central to the development of the neurological disorder Guillain-Barré syndrome. Both diseases raise important questions concerning infection-induced autoimmunity awaiting to be addressed.

Palavras-Chave: Bacterial pathogenesis; Campylobacter jejuni; Helicobacter pylori; Lipid A; Molecular mimicry

Imprenta: Sub-Cellular Biochemistry, v. 53, p. 209-240, 2010

Identificador do objeto digital: 10.1007/978-90-481-9078-2_10

Descritores: Guillain-Barre Syndrome - Biochemistry ; Guillain-Barre Syndrome - Cytopathology ; Guillain-Barre Syndrome - Molecular Structure ; Guillain-Barre Syndrome - Pathogenesis ; Guillain-Barre Syndrome - Antibodies ; Guillain-Barre Syndrome - Autoimmunity ; Guillain-Barre Syndrome - Inflammation ; Guillain-Barre Syndrome - Immunology

Data de publicação: 2010