Abstract P138: Perivascular Adipose Tissues (pvats) Home Distinct 'Active' Immune Cell Niches, Denser Than Non-pvat Adipose Tissues of Healthy Rats

Abstract

Perivascular adipose tissue (PVAT) is protective and reduces the contraction of blood vessels in health. Eosinophils are one of the key players to the anti-contractile nature of PVAT in health. This finding led to our hypothesis that an ‘active’ immune complement exists in healthy PVAT. Male and female Sprague Dawley rats (12-14 weeks age) were used. PVATs from the thoracic aorta (brown APVAT), mesenteric resistance vessels (white MRPVAT), non-PVATs: subscapular (brown SS fat), retroperitoneal (white RP fat) and spleen (positive control) were harvested from each animal. T cells (CD4 and CD8), B cells, NK cells, macrophages, mast cells and neutrophils in the stromal vascular fraction were quantified using 9-color flow cytometry. Activation status (effector/ memory/ regulatory) of macrophages, T and B cells were also determined by flow cytometry. The number of immune cells are normalized to tissue weight (table). MRPVAT has denser total immune population (both sexes) and active macrophage pool (females) vs RP fat. APVAT homes a denser immune niche (females) and active T cell, B cell pools (both sexes) vs SS fat. This is the first study to characterize ‘active’ immune populations in healthy PVATs vs non-PVATs in male and female rats. Further studies to understand the functions of basally active immune cells in healthy PVATs are warranted.