C-type lectin Mincle-dependent and -independent activation of invariant NKT cells by exposure to Helicobacter pylori α-cholesteryl glucosides.

Helicobacter pylori extracts cholesterol from the host and converts it to its glycosides. We found that cholesteryl 6'-O-acyl α-glucoside (ChAcαG) produced by H. pylori is recognised by both invariant Vα14 NKT (iNKT) cells and a C-type lectin receptor Mincle (Clec4e). However, it is unclear how these duplicated recognitions cooperate and contribute to host defence against H. pylori. Among T cell populations in the liver, iNKT cells predominantly expressed the T cell activation marker CD69 just after stimulation with ChAcαG. The production of IFN-γ and IL-4 was strictly dependent on both CD1d and Jα18 expressions, indicating the necessity of iNKT cell activation for the initiation of immune responses. Production of IFN-γ by iNKT cells was markedly reduced by the Mincle deficiency on antigen-presenting cells (APCs), while IL-4 production was not significantly influenced. IL-2 production by iNKT cell hybridomas was also diminished by the Mincle deficiency upon stimulation with APCs previously loaded with ChAcαG. Here, the immune responses of iNKT cell hybridomas stimulated with wild-type APCs were reduced by the addition of anti-IL-12 blocking antibody to the level stimulated with Mincle-deficient APCs. Collectively, these results suggest that iNKT cells can be activated with the cholesteryl glycosides via a Mincle-dependent, IL-12 signal-dependent pathway and a Mincle-independent, invariant TCR signal-dominant pathway. iNKT cells activated via the Mincle-dependent pathway produce IFN-γ-dominant cytokines; hence, they may contribute to enhancing proinflammatory responses against H. pylori infection.