Mycobacterium tuberculosis Infects Human Visceral White Adipocytes and Expresses Dormancy Genes and Inflammatory Cytokines: The Role of Visceral Adipocytes in Latent Tuberculosis Infection

This study explores the role of human visceral white adipocytes (hv-WAD) in latent tuberculosis infection (LTBI). While granulomas and macrophages are traditionally viewed as central to TB latency, emerging evidence highlights adipocytes as significant non-canonical host cells that may facilitate bacterial persistence by providing a protective niche. Unlike the immune-driven environment within granulomas, adipocytes can shield Mycobacterium tuberculosis (Mtb) from immune surveillance, promoting survival. In vitro experiments showed that Mtb invades approximately 39% of hv-WAD within 48–72 h post-infection (hpi). Both avirulent H37Ra and virulent H37Rv Mtb strains, when infecting adipocytes, expressed RNA for key virulence factors (19 kDa, 30 kDa, Ag85b, 5KST, CFP10, and ESAT6) and dormancy-associated genes (Icl1, LipY, WhiB3, SodA, and Tgs1) at 72 hpi. Infection stimulated the production of inflammatory cytokines, notably leading to a fivefold increase in TNF-α with H37Rv (p < 0.01). Additionally, we detected Mtb RNA transcripts (IS6110, 5KST, 30 kDa, CFP10, Ag85) in 68% of biopsies from TB asymptomatic patients. The transcripts suggest a metabolically heterogeneous state of mycobacteria. These findings position visceral fat as a potential reservoir for Mtb in latent TB infection and underscore the development of novel diagnostic strategies targeting adipose tissue.