Hak Chung

Background: Obesity-associated inflammation in white adipose tissue (WAT) worsens outcomes of influenza A virus (IAV) infection. A recently identified thoracic cavity WAT (tcWAT) supports IAV replication. However, tcWAT immune cell composition, functional properties, and role in IAV disease severity remain unclear. Methods: Using a mouse model of diet-induced obesity, flow cytometry, and single-cell RNA sequencing, we compared tcWAT with lung-distal visceral WAT assessing immune cell composition, transcriptomic profiles, inflammatory potential, and impact on IAV pathogenesis. Results: At baseline, tcWAT was uniquely enriched for immune cells with heightened proinflammatory capacity and exhibited a striking predominance of lymphocytic populations, including immature and Satb1+ T cells, the latter expressing gene signatures associated with elevated T-cell activation. Transfer of tcWAT immune cells into IAV-infected recipients accelerated IAV disease severity. IAV infection robustly reshaped tcWAT immune landscape, driving expansion of a B-cell population expressing Zbtb32 and upregulating genes involved in immune regulation and antiviral responses. Concurrently, IAV infection reduced immune populations linked to neutrophil regulation in tcWAT, while these same populations were expanded in the lung. Conclusions: These findings identify lung-proximal tcWAT as a distinct inflammatory tissue that may amplify pathogenic immune responses during IAV infection.

As major cardiac events and heart failure are the leading causes of death among individuals with LCHADD, we are committed to identify better treatment options. To undertake this, we characterized LCHADD cardiomyopathy using a mouse model. We identified a hypertrophic cardiomyopathy with diffuse fibrosis, extensive lipid accumulation, increased oxidative stress, and global sympathetic denervation with long QT intervals and arrhythmia susceptibility likely caused by cardiomyocyte energetic remodeling, altered homeostasis, and cardiac conduction dysregulation.

Processes that promote white adipocyte inflammatory function remain incompletely defined. Here, we demonstrated that type I interferon–dependent (IFN-I–dependent) skewing of adipocyte glycolysis, nicotinamide adenine dinucleotide (NAD ⁺ ) utilization, and pyruvate kinase isozyme M2 (PKM2) function may contribute to increased systemic and tissue inflammation and disease severity in obesity. Notably, chemical and/or genetic inhibition of glycolysis, the NAD ⁺ salvage pathway, or PKM2 restricted IFN-I–dependent increase in adipocyte inflammatory cytokine production. Further, genetic or small molecule targeting of PKM2 function in vivo was sufficient to reduce systemic and tissue inflammation and metabolic disease severity in obese mice, in an adipocyte PKM2-dependent manner. Further, white adipose tissue of individuals living with obesity and metabolic disease, compared with metabolically healthy individuals with obesity, showed an increase in expression of inflammatory and metabolic genes, while small molecule targeting of PKM2 function contributed to reduced IFN-I–driven inflammatory cytokine production by primary human adipocytes. Together, our findings invoke the IFN-I/PKM2 axis as a potential target for modulating adipocyte dysregulated inflammation.