Endoplasmatic reticulum (ER) stress is an imbalance between the load of unfolded proteins and the ability of cellular mechanisms to handle it. Under the influence of this stress, cells activate the unfolded protein response (UPR). The molecular mechanisms of ER stress have been repeatedly linked to metabolic and inflammatory diseases, such as obesity and allergic inflammation. The aim of our study was to investigate if the allergic inflammation in adipocytes affects the expression of UPR pathway genes and Ormdl3 and whether miRNA-665 can modify inflammatory response in adipocytes. We isolated rat preadipocytes and treated them with IL-13 to induce allergic inflammation. Later, we transfected them with miRNA-665 inhibitor. RNA was isolated from adipocytes and analyzed by qPCR. From cell culture medium, we performed an LDH assay and ELISA for secreted IL-6 and TNFα proteins. A comparison between control cells and IL-13-treated cells showed significant differences in the expression of most of the studied UPR pathway genes, Ormdl3 and Bax. Comparing the IL-13-treated cells after miR-665 transfection with non-transfected ones, we observe significant differences only in Ire1α gene. Our research suggests that allergic inflammation induces an adaptive UPR in adipocytes and miR-665 may selectively modify this response, triggering the IRE1/XBP1 axis.
Nowakowska-Lewicka et al. (Thu,) studied this question.