Myeloid mineralocorticoid receptor activation alters metabolism in HFD‐salt fed mice

Abstract

Context and ObjectivesIn obese mice and patients, mineralocorticoid receptor (MR) activation has deleterious consequences on metabolic and cardiovascular parameters. In mice, adipose tissue MR triggers mitochondrial and vascular dysfunction. Adipocyte MR activation induces metabolic and vascular dysfunction in a context of obesity, however, obese adipose tissue is also infiltrated with macrophages, which are capable of expressing MR. Thus, we hypothesised that macrophage MR could also be responsible for metabolic and cardiovascular complications in high‐fat high‐salt diet‐fed mice.MethodsWe fed myeloid cell‐specific MR knock‐out male and female mice (My‐MRKO) with a 6‐week high fat – high salt diet (60% kcal from fat, 1.2% salt in drinking water) and studied weight gain, whole body and specific organs composition by nuclear magnetic resonance and insulin sensitivity to explore the metabolic phenotype. Blood pressure measurements by plethysmography and vascular reactivity studies by wire myography were also performed to characterise the cardiovascular phenotype.ResultsMy‐MRKO male mice under high fat – high salt diet displayed reduced weight (37.8 g [interquartile range 34.1–40.8] vs 42.5 g [39.5–45.2]; P = 0.0128), preserved muscle mass (61.5 % [55.8–63.3] vs 56.8 % [54.1–58.5]; P = 0.0337) and a strong tendency to decreased fat mass (26.1 % [23.7–33.9] vs 31.7 % [27.1–35.4]; P = 0.0728). Moreover, liver fat content at sacrifice was decreased (5.8 % [2.1–9.1] vs 9.3 % [5.9–13.4]; P = 0.0491). Those effects were not observed in female mice. Fasting glycaemia was decreased in male My‐MRKO mice (9.2 mmol/L [6.4–12.8] vs 13.2 mmol/L [10.4–16.1]; P = 0.0005) and insulin resistance was decreased in both gender (area under curve 9915 [9398–10043] vs 11550 [9795–12848]; P = 0.0458 in males, 8291 [7812–8884] vs 9544 [8918–9735]; P = 0.0177 in females), as assessed by an insulin tolerance test. A clear effect was observed on blood pressure only in female mice (blood pressure 96 mmHg [94–97] vs 106 mmHg [104–109]; P = 0.0004), whereas there was no modification in mesenteric arteries vascular reactivity in both gender.ConclusionsThus, our findings show that myeloid cell‐MR regulates systemic metabolic parameters, highlighting a new role in obesity and its associated complications for MR expressed in myeloid cells.Support or Funding InformationSorbonne Université, Inserm, CARMMA‐RHU