Sterile liver injury induces a protective tissue-resident cDC1-ILC1 circuit through cDC1-intrinsic cGAS-STING-dependent IL-12 production

Tissue-resident immune cells are critical to the initiation and potentiation of inflammation. However, the tissue-protective cellular communication networks initiated by resident immunity during sterile inflammation are not well understood. Using single-cell transcriptomic analysis, we show the liver-resident cell connectome and signalome during acute liver injury. These analyses identify Il12b as a central regulator of liver injury-associated changes in gene expression. Interleukin (IL)-12 produced by conventional type 1 dendritic cells (cDC1s) is required for protection during acute injury through activation of interferon (IFN)-γ production by liver-resident type 1 innate lymphoid cells (ILC1s). Using a targeted in vivo CRISPR-Cas9 screen of innate immune sensing pathways, we find that cDC1-intrinsic cGAS-STING signaling acts upstream of IL-12 production to initiate early protective immune responses. Our study identifies the core communication hubs initiated by tissue-resident innate immune cells during sterile inflammation in vivo and implicates cDC1-derived IL-12 as an important regulator of this process.

Adipose cDC1s contribute to obesity-associated inflammation through STING-dependent IL-12 production

Obesity is associated with chronic low-grade white adipose tissue (WAT) inflammation that can contribute to the development of insulin resistance in mammals. Previous studies have identified interleukin (IL)-12 as a critical upstream regulator of WAT inflammation and metabolic dysfunction during obesity. However, the cell types and mechanisms that initiate WAT IL-12 production remain unclear. Here we show that conventional type 1 dendritic cells (cDC1s) are the cellular source of WAT IL-12 during obesity through analysis of mouse and human WAT single-cell transcriptomic datasets, IL-12 reporter mice and IL-12p70 protein levels by enzyme-linked immunosorbent assay. We demonstrate that cDC1s contribute to obesity-associated inflammation by increasing group 1 innate lymphocyte interferon-γ production and inflammatory macrophage accumulation. Inducible depletion of cDC1s increased WAT insulin sensitivity and systemic glucose tolerance during diet-induced obesity. Mechanistically, endocytosis of apoptotic bodies containing self-DNA by WAT cDC1s drives stimulator of interferon genes (STING)-dependent IL-12 production. Together, these results suggest that WAT cDC1s act as critical regulators of adipose tissue inflammation and metabolic dysfunction during obesity.

Progressive Eyelid Lesions in a Woman With Essential Thrombocythemia

A 75-year-old woman with a history of essential thrombocythemia presented with 3 months of progressively enlarging right upper eyelid lesions. Examination revealed a thickened eyelid margin, madarosis, and erythema with some tenderness to palpation but an otherwise normal ocular examination. What would you do next?