NOS2 and obesity due to melanocortin 4 receptor deficiency: In the current study, we used a mouse model of diet-induced obesity to test the hypothesis that perilymphatic low-grade inflammation is a major regulator of lymphatic dysfunction and that this process is dependent on T cell infiltration, decreased capillary lymphatic density, expression of inducible nitric oxide synthase (iNOS), and inhibition of collecting lymphatic pumping frequency.