Lysosomal exocytosis by macrophages as a druggable mechanism for anti-inflammatory clearance of dead adipocytes in adipose tissue

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

• Level A · Stronger Clinical Evidence
• Level B · Emerging clinical evidence with positive signals
• Level C · Early human research exploring benefits
• Level D · Scientific groundwork from lab and animal studies
• Emerging · Emerging topic under active research

Abstract (original English)

The clearance of dead adipocytes in adipose tissue (AT) poses a major challenge due to their large size, which exceeds the phagocytic capacity of macrophages and prevents classical, anti-inflammatory efferocytosis. Instead, adipose tissue macrophages (ATMs) accumulate around dying adipocytes, forming crown-like structures (CLS), and engage in lysosomal exocytosis - the extracellular degradation of adipocytes. In this study, we used an ex vivo explant model of murine epididymal white AT, cultured over seven days to investigate pharmacological strategies that modulate lysosomal exocytosis. We observed a progressive increase in CLS formation, secretion of the lysosomal enzymes ß-Hexosaminidase A (HEXA) and lysosomal acid lipase (LAL), and surface abundance of LAMP1 and LAMP2, confirming ATMs as key mediators of this process. Notably, activation of lysosomal exocytosis with the mTOR inhibitor Rapamycin enhanced adipocyte clearance and significantly reduced inflammatory ATM abundance and TNF-α secretion. Bulk RNA sequencing of ATMs revealed a highly significant impact of Rapamyin on ATM proliferation. In contrast, inhibition of lysosomal exocytosis with PIKfyve inhibitor Apilimod or targeted inhibition of LAL using Lalistat-2 disrupted lysosomal function and promoted a pro-inflammatory ATM phenotype. Our findings highlight lysosomal exocytosis as a critical pathway for the resolutio

Evidence level

Evidence from laboratory and animal studies provides groundwork for understanding mechanisms and potential before human studies continue.

Browse all related research

Filter the research library by this study's title keywords, author, or publication year.