Structural modifications ofHelicobacter pylorilipopolysaccharide: An idea for how to live in peace

Abstract

In this review, we discuss the findings and concepts underlying the "persistence mechanisms" of Helicobacter pylori (H. pylori), a spiral-shaped, Gram-negative rod bacterium that was discovered as a gastric pathogen by Marshall and Warren in 1984. H. pylori colonizes the gastric mucosa of nearly half of the human population. Infections appear in early childhood and, if not treated, persist for life. The presence or absence of symptoms and their severity depend on multiple bacterial components, host susceptibility and environmental factors, which allow H. pylori to switch between pathogenicity and commensalism. Many studies have shown that H. pylori components may facilitate the colonization process and the immune response of the host during the course of H. pylori infection. These H. pylori-driven interactions might result from positive or negative modulation. Among the negative immunomodulators, a prominent position is occupied by a vacuolating toxin A (VacA) and cytotoxin-associated gene A (CagA) protein. However, in light of the recent studies that are presented in this review, it is necessary to enrich this panel with H. pylori lipopolysaccharide (LPS). Together with CagA and VacA, LPS suppresses the elimination of H. pylori bacteria from the gastric mucosa by interfering with the activity of innate and adaptive immune cells, diminishing the inflammatory response, and affecting the adaptive T lymphocyte response, thus facilitating the development of chronic infections. The complex strategy of H. pylori bacteria for survival in the gastric mucosa of the host involves both structural modifications of LPS lipid A to diminish its endotoxic properties and the expression and variation of Lewis determinants, arranged in O-specific chains of H. pylori LPS. By mimicking host components, this phenomenon leaves these bacteria "invisible" to immune cells. Together, these mechanisms allow H. pylori to survive and live for many years within their hosts.

Unraveling the factors and mechanism involved in persistence: Host‐pathogen interactions in Helicobacter pylori

“…Sometimes, microbes mimic some antigenic and molecular forms of the host system, which help in ducking the immune responses but it can lead to autoimmune diseases. Host immune system produces autoimmune antibodies against the mimicked components, which are produced by H. pylori cell . It has been proved that O‐side chain of LPS of H. pylori strain (NCTC 11637), mimic the Lewis x blood group antigen (present in gastric mucosa) .…”

Mucoid and coccoid Helicobacter pylori with fast growth and antibiotic resistance

“…Lipid A as the bioactive center of LPS and responsible for its endotoxic activity is composed of 1,6‐linked D‐glucosamine disaccharide which is phosphorylated and has up to six fatty acid residues . To survive and establish a long‐term chronic infection, H pylori modifies the structure of its LPS lipid A to diminish its endotoxic properties and also alters expression and variation of Lewis determinants arranged in O‐specific chains of H pylori LPS . Cell membrane of H pylori is unique in accumulating large amounts of cholesterol that comprises >70% of cellular neutral lipids .…”

Toll-like receptor 2: An important immunomodulatory molecule during Helicobacter pylori infection

“…HP-LPS may enter into the lamina propria by transportation through goblet cells, certain DCs or may enter into the Peyer's patches via M cells[79,80]. In addition to gastrointestinal epithelial cells, HP-LPS can bind to various immune cells infiltrating the mucosal basal lamina.…”

“…The binding of TLR2 to H. pylori LPSDuring H. pylori infection, the HP-LPS may facilitate the colonization of gastric mucosa through interaction with extracellular matrix proteins[79]. HP-LPS may enter into the lamina propria by transportation through goblet cells, certain DCs or may enter into the Peyer's patches via M cells[79,80].…”

“…In addition to gastrointestinal epithelial cells, HP-LPS can bind to various immune cells infiltrating the mucosal basal lamina. Moreover, the increased permeability of the gastrointestinal epithelium due to the activity of H. pylori proteins, such as urease and vacuolating cytotoxin, may facilitate the entering of HP-LPS into the lamina propria and then into the circulation[79].…”