The Transcription Factor RXRα in CD11c+ APCs Regulates Intestinal Immune Homeostasis and Inflammation.

APCs such as dendritic cells and macrophages play a pivotal role in mediating immune tolerance and restoring intestinal immune homeostasis by limiting inflammatory responses against commensal bacteria. However, cell-intrinsic molecular regulators critical for programming intestinal APCs to a regulatory state rather than an inflammatory state are unknown. In this study, we report that the transcription factor retinoid X receptor α (RXRα) signaling in CD11c+ APCs is essential for suppressing intestinal inflammation by imparting an anti-inflammatory phenotype. Using a mouse model of ulcerative colitis, we demonstrated that targeted deletion of RXRα in CD11c+ APCs in mice resulted in the loss of T cell homeostasis with enhanced intestinal inflammation and increased histopathological severity of colonic tissue. This was due to the increased production of proinflammatory cytokines that drive Th1/Th17 responses and decreased expression of immune-regulatory factors that promote regulatory T cell differentiation in the colon. Consistent with these findings, pharmacological activation of the RXRα pathway alleviated colitis severity in mice by suppressing the expression of inflammatory cytokines and limiting Th1/Th17 cell differentiation. These findings identify an essential role for RXRα in APCs in regulating intestinal immune homeostasis and inflammation. Thus, manipulating the RXRα pathway could provide novel opportunities for enhancing regulatory responses and dampening colonic inflammation.

Inhibition of Cyclooxygenase Enzyme by Bioflavonoids in Horsegram Seeds Alleviates Pain and Inflammation.

BACKGROUND: Inflammation and pain, mainly induced by the prostaglandins synthesized by the cyclooxygenase enzymes, may cause distress. To overcome this unpleasant stress in a safer manner, numerous natural molecules are proven for modulating the COX enzymes. Epicatechin and daidzein are two bioactive natural compounds present in horsegram, a legume known for its medicinal properties. OBJECTIVE: The present study aims at evaluating the potential of horsegram, and some of its bioactive molecules, to be used as an anti-inflammatory and analgesic agent mediated by the inhibition of COX enzymes, which can be recommended as a substitute for chemically synthesized NSAIDs. METHODS: The present work involved the quantification of epicatechin and daidzein present in horsegram seeds. The COX enzyme inhibitory nature of epicatechin and daidzein was tested using in silico docking analysis with Autodock software and was further confirmed by in vitro COX inhibitory biochemical assays. Furthermore, the anti-inflammatory and analgesic activities of the horsegram seeds were evaluated in animal experiments. RESULTS: Horsegram seeds contain 158.1 microgram/g and 6.51 microgram/g of epicatechin and daidzein respectively. The docking studies reveal that both the bioactive molecules exhibit better binding efficiency with COX-2 protein as compared to COX-1. Hence, in vitro COX-2 inhibitory assay was performed for epicatechin, daidzein and compared with known analgesic agent diclofenac which revealed a pronounced dose dependent inhibitory activity. Furthermore, the analgesic and anti-inflammatory activity of horsegram in experimental animals exhibited a dose dependent effect which might be due to the presence of the bioactive compounds such as epicatechin and daidzein. CONCLUSION: The results suggest that epicatechin and daidzein present in horsegram are potent cyclooxygenase inhibitors and thus would be helpful in the management of inflammation and pain.