cGAS deficiency enhances inflammasome activation in macrophages and inflammatory pathology in pristane-induced lupus

Abstract

IntroductionType I interferon (IFN) plays a vital role in the pathogenesis of systemic lupus erythematosus. Cyclic GMP AMP synthase (cGAS) is a cytosolic DNA sensor that recognizes dsDNA and creates cGAMP to activate STING-mediated type I IFN production. The activation of STING induces lupus disease in Fcgr2b deficient mice through the differentiation of dendritic cells. In contrast, Cgas-deficient mice could be generated more autoantibody production and proteinuria in pristane-induced lupus (PIL). These data suggested that the other dsDNA sensors could be involved in lupus development mechanisms.MethodsThis study aimed to identify the cGAS-mediated mechanisms contributing to lupus pathogenesis in PIL. The Cgas-deficient and WT mice were induced lupus disease with pristane and subsequently analyzed autoantibody, histopathology, and immunophenotypes. The lung tissues were analyzed with the expression profiles by RT-PCR and western blot. The bone marrow-derived macrophages were stimulated with inflammasome activators and observed pyroptosis.ResultsThe Cgas-/- mice developed more severe pulmonary hemorrhage and autoantibody production than WT mice. The activated dendritic cells, IFN-g-, and IL-17a-producing T helper cells, and infiltrated macrophages in the lung were detected in Cgas-/- mice higher than in WT mice. We observed an increase in expression of Aim2, Casp11, and Ifi16 in the lung and serum IL-1a but IL-1b in pristane-injected Cgas-/- mice. The rise of Caspase-11 in the lung of pristane-injected Cgas-/- mice suggested noncanonical inflammasome activation. The activation of AIM2 and NLRP3 inflammasomes in bone marrow-derived macrophages (BMDMs) enhanced the number of dead cells in Cgas-/- mice compared with WT mice. Activation of the inflammasome significantly induced pyroptosis in Cgas-/- BMDMs. The dsDNA level, but not mitochondrial DNA, increased dramatically in pristane-injected Cgas-/- mice suggesting the dsDNA could be a ligand activating inflammasomes. The cGAS agonist-induced BMDM activation in the Cgas-/- mice indicated that the activation of DNA sensors other than cGAS enhanced activated macrophages.ConclusionThese findings suggested that cGAS hampers the unusual noncanonical inflammasome activation through other DNA sensors.

Roles of the Caspase-11 Non-Canonical Inflammasome in Rheumatic Diseases

“…cGAS deficiency enhances lupus-like symptoms and inflammatory pathology in a pristane-induced mouse model of lupus [87]. cGAS deficiency also increases the expression of the caspase-11 gene, leading to activation of the caspase-11 non-canonical inflammasome in the lungs of pristane-induced lupus mice [87]. These results suggest that the caspase-11 noncanonical inflammasome is activated during SLE pathology by increasing caspase-11 expression, which is inhibited by cGAS.…”

“…Kumpunya et al, demonstrated the functional cooperation of the caspase-11 non-canonical inflammasome with cyclic GMP AMP synthase (cGAS) during SLE pathogenesis in a murine lupus model. cGAS deficiency enhances lupus-like symptoms and inflammatory pathology in a pristane-induced mouse model of lupus [87]. cGAS deficiency also increases the expression of the caspase-11 gene, leading to activation of the caspase-11 non-canonical inflammasome in the lungs of pristane-induced lupus mice [87].…”

The STING inhibitor (ISD-017) reduces glomerulonephritis in 129.B6.Fcgr2b-deficient mice

“…The pathology grading from kidney sections was blinded by an experienced researcher. As previously described, the histology scores were reported as glomerular and interstitial scores 38 – 39 . In brief, glomerular scores were defined as 0 = normal; 1 = focal, mild, or early proliferative; 2 = moderate or definite proliferative; 3 = diffuse and focal or diffuse proliferative; 4 = severe diffuse proliferative with crescent/sclerosis, and interstitial scores were defined as 0 = normal; 1 = focal or small pockets (10–15 cells) of mononuclear cells (MNC); 2 = focal infiltrates (15–30 cells); 3 = multifocal extensive infiltrates with necrosis; 4 = multifocal or diffuse and extensive with necrosis.…”

Elucidating the function of STING in systemic lupus erythematosus through the STING Goldenticket mouse mutant

“…Cell viability (eBioscience™ Fixable Viability Dye eFluor™ 780, #65-0865-14, Thermo Fisher Scientific, CA, USA). For cell surface marker staining, splenocytes were isolated and prepared as previously described 32 .…”