Characterization of death receptor 3‐dependent aortic changes during inflammatory arthritis

Murine collagen‐induced arthritis (mCIA) is characterized by decreased vascular constriction responses and increased MMP‐9. Here, we describe additional histological alterations within the aorta and surrounding perivascular adipose tissue (PVAT), study the role of PVAT in constriction response, and investigate the potential involvement of death receptor 3 (DR3). mCIA was induced in wild‐type (WT) and DR3(−/−) mice with nonimmunized, age‐matched controls. Vascular function was determined in isolated aortic rings ±PVAT, using isometric tension myography, in response to cumulative serotonin concentrations. Cellular expression of F4/80 (macrophages), Ly6G (neutrophils), DR3, and MMP‐9 was determined using immunohistochemistry. In WTs, arthritis‐induced vascular dysfunction was associated with increased F4/80+ macrophages and increased DR3 expression in the aorta and PVAT. MMP‐9 was also up‐regulated in PVAT, but did not correlate with alterations of PVAT intact constriction. DR3(−/−) mice inherently showed increased leukocyte numbers and MMP‐9 expression in the PVAT, but retained the same nonarthritic constriction response as DR3WT mice ±PVAT. Arthritic DR3(−/−) mice had a worsened constriction response than DR3WT and showed an influx of neutrophils to the aorta and PVAT. Macrophage numbers were also up‐regulated in DR3(−/−) PVAT. Despite this influx, PVAT intact DR3(−/−) constriction responses were restored to the same level as DR3WT. Impaired vascular constriction in inflammatory arthritis occurs independently of total MMP‐9 levels, but correlates with macrophage and neutrophil ingress. Ablating DR3 worsens the associated vasculature dysfunction, however, DR3(−/−) PVAT is able to protect the aorta against aberrant vasoconstriction caused in this model.