Morphine dysregulates Paneth cell antimicrobial peptide secretion in a TLR2 dependent manner.

Abstract

Abstract Opioids are the gold standard for moderate to severe pain management. Although, the co-morbidities associated with chronic morphine use on systemic immune function has been well demonstrated by our lab and others its effect on mucosal immunity and gut homeostasis are less well defined. We have recently demonstrated that morphine treatment disrupts intestinal epithelial barrier function and suppresses systemic immune function leading to altered gut microbial dysbiosis and inflammation. We have also shown in vivo that morphine can alter the immune response by APCs leading to reduced host immune response. However, the cross talk between the gut microbiome and host intestinal epithelium and immune cells has never been explored. Paneth cells are one of the main secretory component of intestinal epithelial layer that secrete antimicrobial peptides which maintains gut homeostasis between pathogenic and commensal microbes. They also secrete pro-inflammatory cytokines which regulate the functions of mucosal immune cells. In both a murine in vivo model and in an in vitro organoid epithelial culture model we show a direct effect of morphine on paneth cells. Intraperitonial morphine treatment significantly increases the transcription level of antimicrobial peptides, a-defensins, lysozyme, Regg as well as intestinal pro-inflammatory cytokine IL1b, IL6 and TNFa levels in C57/B6 mice model. These results are also corroborated in in vitro organoid cultures. Surprisingly, these effects were completely abolished in a Toll-like receptor-2 (TLR2) knock out mice suggesting that the effect is mediated through TLR2. The role of TLR 2 and the cell type that mediates morphine’s effects will be further investigated using TLR2 floxed mice.