Full length articleDual genetic absence of STAT6 and IL-10 does not abrogate anti-hyperglycemic effects of Schistosoma mansoni in streptozotocin-treated diabetic mice

•Schistosoma mansoni infection reduces hyperglycemia induced by multiple low -dose streptozotocin injection in mice.•The anti-hyperglycemic effect of S. mansoni is not dependent on Treg, STAT6 and IL-10.•T-cell cytokine modulations are not relevant to the anti-hyperglycemic effects.•S. manosni induces M2-like macrophage activation in the absence of both STAT6 and IL-10.

Schistosoma mansoni (Sm) is known to exert protective effects against various allergic and autoimmune disorders. It has been reported that this parasite protects NOD mice from spontaneous type 1 diabetes (T1D) and ameliorates streptozotocin (STZ)-induced T1D in wild-type mice. Here, we tried to clarify the anti-diabetic mechanisms of Sm in the latter model. Sm infection partially prevented the degradation of pancreatic islets and hyperglycemia in multiple low-dose (MLD) STZ-treated mice. Neither Treg cell depletion nor genetic absences of IL-10 and/or STAT6 abrogated the anti-hyperglycemic effects of Sm. Among M2 macrophage markers, Arg-1 and Ym1, but not Retnla, remained up-regulated in the pancreatic lymph nodes and in the spleens of STAT6/IL-10 double deficient (DKO) mice. Collectively, it is suggested that Sm exerts anti-diabetic effects on this experimental T1D model via Treg/IL-4/IL-13/IL-10-independent mechanisms. Augmented expressions of Arg-1 and Ym1 in the lymphoid organs adjacent to pancreas may be relevant to the anti-diabetic effects of Sm.

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