Observations from several studies extend the functional repertoir

Observations from several studies extend the functional repertoire of CagA and the cag type IV secretion system BMS-777607 in vivo in particular, providing further mechanistic understanding of how these important determinants engage and activate host signalling pathways important in

the development of disease. Helicobacter pylori has evolved numerous strategies to enable its survival and persistence within the gastric mucosa including diverse mechanisms to evade host immune surveillance. Further investigation of one such mechanism, protein glycosylation, has revealed three different glycosylation pathways in H. pylori and the presence of numerous potential glycoproteins [1]. Recently determined glycosylated proteins in addition to flagellin include catalase and lipopolysaccharide (LPS) biosynthesis enzymes [1]. Avoidance of host immune surveillance is also effected by molecular mimicry and phase variation, two mechanisms relevant to Lewis (Le) antigen presentation on the bacterial cell surface. An additional Le gene (jhp0562) has recently been characterized and found to contribute to both Type 1 and Type 2 pathways of Le synthesis [2]. Moreover, homology between jhp0562 and the downstream jhp0563, encoding β-(1,3)galT, promotes intragenomic recombination, increasing the diversity

of Le phenotypes through the generation of chimeric alleles. Intragenomic SAR245409 solubility dmso recombination likely also GNAT2 accounts for the absence/loss of jhp0562 in some strains and the size heterogeneity of jhp0562 alleles in different geographic strain populations [3]. Molecular mimicry similarly defines the mechanism of immune evasion effected by the variable O-antigen moiety of LPS. Modifications of the LPS lipid A domain that reduce overall negative charge also provide resistance to host cell-lytic cationic antimicrobial peptides (CAMPs). Recent work has identified that dephosphorylation of lipid A is a critical determinant in CAMP resistance [4]. Characterization of the phosphatase

enzymes involved has shown that lipid A dephosphorylation also attenuates the activation of TLR4 thereby reducing host clearance and promoting colonization. In addition to variable surface presentation, the characteristic helical shape of H. pylori has also been shown to influence colonization potential. Two further proteins involved in peptidoglycan modification and cell shape determination have been defined in a study that shows the critical importance of cell shape for motility and penetration of H. pylori within a viscous medium such as gastric mucous [5]. Helicobacter pylori also colonizes the epithelial cell surface from where essential micronutrients such as iron are acquired to support microcolony survival. It is now demonstrated that microcolonies utilize host holotransferrin (iron-saturated transferrin) as an iron source by inducing mislocalization of the basolateral transferrin receptor to the apical surface [6].

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