P311 regulates immune cells towards anti-inflammatory phenotype in adipose tissue

Adipose tissue is a heterogeneous organ that regulates metabolic health and is functionally associated to the immune system. This heterogeneity extends to adipose tissue resident immune cell populations including M1/M2 macrophages, neutrophils, B-cells, T-cells etc. along with adipocytes, preadipocytes and stromal vascular fraction. Acute and chronic inflammation of adipose tissue brought on by ageing and disease states leads to immune cell dysfunction as well as infiltration of pro-inflammatory immune cell populations. This results in a dramatic remodeling of the immune cell ecosystem within adipose tissue. This shift is associated with increased risk of metabolic disorders such as obesity, insulin resistance, type 2 diabetes, and cardiovascular disease. Our research focuses on P311, a protein that regulates adipogenesis. As adipogenic processes are intertwined with systemic and adipose specific inflammation we focused on examining the role of P311 on immune cell function in adipose tissue. We used Nano-string GeoMax 3D profiler panels to verify the immune profiles of subcutaneous white adipose tissue (scWAT) of P311 knockout (P311KO) mice and C57BL/6 control (wildtype) mice. We overexpressed P311 by transfecting pcP311 plasmid into Raw 264.7 cells and empty vector control to verify the macrophage polarization using western blotting, qPCR method and FACs analyses methods. Our results showed that the P311 knockouts (P311 KOs) exhibit a pro-inflammatory phenotype as indicated by increased expression of inflammatory gene markers GZNB and INFGR in NanoString immune cell profiling studies. Subsequently, P311 KOs showed significant decrease in total macrophage population (F4/80) while simultaneously showing an increase in M1 proinflammatory macrophage profile as indicated by increased CD86 and CD11c expression when compared to matched controls. We also observed a significant decrease in crownlike structure associated macrophages (CD68 crown like structure marker) in P311 KOs compared to WTs. Furthermore, for the first time, our studies showed the presence of P311 in macrophages, Raw 264.7. Additional studies indicated that P311 overexpression suppressed M1 phenotype in Raw cells and activated macrophages towards M2 phenotype through the JAK/STAT6 signaling pathway. Our trans-well migration studies indicated that P311 overexpression enhanced macrophage migration, more specifically in presence of proinflammatory conditions like treatment with 3T3L1-adipocyte medium loaded with adipocyte secreted lipids and adipokines/cytokines from matured adipocytes. Our results show for the first time that P311 is present in macrophages along with adipocytes. P311 potentially enhances macrophage infiltration in adipose tissue dysfunction and supports immune cell activation towards anti-inflammatory phenotype. This study was supported by SCORE/SC1 grant funding to KB (5SC1GM141937). We acknowledge the support to MSM Core Facility (RCMI grant, 5U54MD0076037). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.