# Restoring Lysosomes in Adipose Tissue Macrophages Mitigates Obesity-Induced Inflammation and Insulin Resistance

## TL;DR

Restoring lysosomal function in fat tissue macrophages reduces obesity-related inflammation and insulin resistance in mice.

## Contribution

This study identifies lysosomal dysfunction in adipose tissue macrophages as a driver of obesity-related inflammation and shows that restoring lysosomal function mitigates metabolic dysfunction.

## Key findings

- Obesity leads to lysosomal dysfunction in adipose tissue macrophages despite increased lysosomal abundance.
- Pharmacological restoration of lysosomal function with HPβCD improves glucose tolerance and reduces pro-inflammatory immune cells in visceral fat.
- HPβCD suppresses inflammatory gene expression in macrophages and reverses lysosomal stress-induced inflammation.

## Abstract

Adipose tissue macrophages (ATMs) are key mediators of obesity-induced inflammation and insulin resistance. However, the contribution of lysosomal dysfunction to ATM inflammatory activation remains poorly defined. Here, we characterized lysosomal structural and functional alterations in ATMs during obesity and examined whether pharmacological restoration of lysosomal function using 2-hydroxypropyl-β-cyclodextrin (HPβCD) ameliorates metabolic inflammation. In diet-induced obese C57BL/6J male mice, adipose tissue exhibited increased lysosomal abundance, accompanied by reduced cathepsin L+V expression, modestly increased lysosomal acid lipase levels, and decreased expression of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis. Despite expanded lysosomal content, ATMs displayed impaired lysosomal acidification, indicating functional lysosomal dysfunction. Intraperitoneal administration of HPβCD for two weeks significantly improved glucose tolerance and insulin sensitivity without affecting body weight. Flow cytometric analysis revealed reduced pro-inflammatory M1 ATMs and CD8+ T lymphocytes in visceral adipose tissue, whereas immune cell populations in subcutaneous adipose tissue, blood, and spleen remained unchanged. In vitro, HPβCD suppressed pro-inflammatory gene expression in both classically and metabolically activated macrophages and attenuated inflammatory responses induced by lysosomal stressors, including bafilomycin A1 and chloroquine, while restoring TFEB expression. Collectively, these findings demonstrate that obesity is associated with lysosomal dysfunction in ATMs and that restoration of lysosomal function alleviates adipose tissue inflammation and metabolic dysfunction, highlighting lysosomal regulation in ATMs as a potential therapeutic target for obesity-associated metabolic diseases.