Sweeney, C. A. P. | bioRxiv Science

bioRxiv2023

MARCO in alveolar macrophages negatively regulates Ace expression and aldosterone production

Aldosterone is a potent cholesterol-derived steroid hormone that plays a major role in controlling blood pressure via regulation of blood volume. The release of aldosterone is typically controlled by the renin-angiotensin aldosterone system, situated in the adrenal glands, kidneys, and lungs. Here, we reveal that the class A scavenger receptor MARCO, expressed on alveolar macrophages, negatively regulates aldosterone production and suppresses angiotensin converting enzyme (Ace) expression in the lungs of male mice. Collectively, our findings point to alveolar macrophages as additional players in the renin-angiotensin-aldosterone system and introduce a novel example of interplay between the immune and endocrine systems.

immunology↗

bioRxiv2023

Distinct adrenal gland macrophages regulate corticosteroid production

The adrenal glands are hormone secreting glands that sit on top of the kidneys. Adrenal glands produce glucocorticoids, mineralocorticoids, and catecholamines, and are therefore critical regulators of the stress response, the immune response, metabolism, and blood pressure. Despite being identified for more that 30 years, our understanding of adrenal macrophages remains incomplete. In numerous other tissues, macrophages carry out a plethora of physiological and homeostatic roles in addition to their classical immune functions. The aim of this study was to characterise the macrophage compartment of the adrenal gland and assess its contribution to adrenal function. Using an in vivo approach, we herein describe two morphologically and spatially distinct subsets of adrenal macrophages - dendritic-like macrophages that are present throughout the gland in young and old mice, and "foamy" lipid-laden macrophages that accumulate in the murine adrenal cortex in an age and diet-dependent manner. Furthermore, we present data showing that these foamy-like macrophages accumulate cholesterol and thereby regulate adrenal hormonal output, at steady state and in the context of obesity. We hereby provide novel insights into the physiological roles of macrophages in the adrenal gland and the mechanisms by which adrenal hormone production is regulated.

immunology↗