The IL-6 family cytokine, oncostatin M (OSM), has several physiological roles, but its exact role in adipose tissue homeostasis is still unclear. We recently reported that high-fat diet-fed male mice with an adipocyte-specific deletion of the OSM-specific receptor (OSMR FKO mice) were insulin-resistant and had increased markers of inflammation in epididymal adipose tissue (eWAT). In the current study, we more closely examined eWAT stromal cell populations in high-fat fed OSMR FKO mice using flow cytometry. Results from flow cytometry studies revealed that, despite no differences in eWAT weights between genotypes, OSMR FKO mice had significantly fewer stromal cells per gram eWAT. Although there were fewer stromal cells overall, a significantly higher percentage of these cells were CD45+ leukocytes. Significant decreases in the numbers of adipose tissue macrophages (CD64+; CD11c+/-) and preadipocytes (CD45-; CD31-; Sca1+) were also observed in OSMR FKO eWAT. A cytokine array was performed on eWAT to assess differences in tissue cytokine profiles that may contribute to the alterations observed in stromal cell populations. Array results indicated a significant decrease in stromal cell-derived factor 1 (SDF1) protein expression in eWAT of OSMR FKO mice. Future studies will focus on the role of adipocyte OSM signaling as a regulator of adipose tissue SDF1 production and stromal cell homeostasis. Overall, our results suggest a homeostatic role for adipocyte OSM signaling in the maintenance of stromal cell populations in gonadal fat.
C.M. Elks: None.
