The perineurium integrates leptin with its sympathetic outflow to protect against obesity.

The regulatory mechanism of leptin's afferent action in the brain is contingent upon the efferent sympathetic innervation of white and brown adipose tissues. Nonetheless, the peripheral regulation governing the afferent-efferent balance remains ambiguous. Here we show the enriched expression of both leptin receptor (Lepr) and β2-adrenergic receptor (Adrb2) in perineurial cells that form a barrier around sympathetic ganglia and nerve bundles in adipose tissues, using single-cell RNA sequencing on mouse sympathetic ganglia. Lepr+ sympathetic perineurial cells (SPCs) are molecularly similar to endothelial cells. Conditional knockout of Adrb2 in Lepr+ cells, including SPCs, predisposes male mice to obesity by lowering energy expenditure and thermogenesis without affecting food intake. Notably, obesity-associated hyperleptinaemia causes apoptosis in SPCs, disrupting the perineurial barrier and concomitant adipose sympathetic neuropathy. This deleterious effect can be reversed by partial reduction of leptin or sympathomimetic β2-adrenergic receptor agonism. Clinically, we observed a male-specific synergistic effect of LEPR and ADRB2 polymorphisms on increased body mass index risk in a large European population. We propose that SPCs coordinate the afferent and efferent arms of the neuroendocrine loop of leptin action to regulate energy expenditure and body weight.