Background: Inflammation is a primary contributor to early graft loss and poor islet engraftment. Human amniotic epithelial cells (hAEC) possess regenerative, immunomodulatory and anti-inflammatory properties. In particular, these cells express HLA-G and HLA-E, involved in immunomodulation and immune tolerance. Here, we hypothesized that hAECs could protect islets from cellular damage induced by proinflammatory cytokines and we assessed the cytokine-induced expression of HLA-G and HLA-E in hAECs. 

Methods: Rat islets were cultured with or without hAECs for 24 hours, followed by 48- hour exposure to IFN-γ, TNF-α and IL-1β. Controls included mono or cocultures without cytokines. For all conditions, glucose stimulated insulin secretion (GSIS), apoptosis by detection of histone-associated DNA fragments, and Th1/Th2 cytokines secreted in the culture media were evaluated by ELISA. Gene expression modifications were assessed by qPCR. hAEC surface marker expression (CD105, CD90, CD326, HLA-E, HLA-G, SSEA-4) was assessed by flow cytometry after culture in control culture medium or in medium containing various concentrations of human recombinant IFN-γ for 24–48H. 

Results: Exposure to a pro-inflammatory cocktail significantly increased the secretion of the anti-inflammatory cytokines IL6, IL10 and G-CSF by hAECs at both 24H and 48H. IL6, IL8 and IL10 gene expression was significantly upregulated, as well as HLA-G and HLAE. This correlated with an upregulation of STAT1, STAT3 and NF-κB1gene expression levels. RI co-cultured with hAECs maintained a normal insulin secretion after cytokine exposure compared to RI cultured alone, and a significantly lower apoptosis rate.

Conclusions: In conclusion, hAECs increase their anti-inflammatory and immunomodulatory potentials when exposed to inflammation in vitro, and protect pancreatic islets against pro-inflammatory cytokines in a coculture set-up.