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Objectives: This study aimed to explore the changes of four major inflammasomes in adult-onset Still's disease (AOSD) and preliminarily evaluate the therapeutic effect of carboxyamidotriazole (CAI), which has previously been reported to have the significant anti-inflammatory activity. Method: The mRNA expressions of proinflammatory cytokines and inflammasome components in peripheral blood mononuclear cells (PBMCs) from AOSD patients and healthy controls (HC) were determined by reverse transcription-quantitative PCR. Poly(dA:dT)-induced AIM2 inflammasome and flagellin-induced NLRC4 inflammasome activation models were established in bone marrow–derived macrophages (BMDMs). The levels of cytokines in serum and culture supernatants were measured by ELISA method. Results: The serum levels of IL-1β, IL-6, and TNF-α in AOSD patients were significantly higher than those in HC. However, the mRNA expressions of IL-1β, IL-6, IL-18, and TNF-α in PBMCs did not differ markedly in AOSD patients in comparison with HC. Significantly increased mRNA levels of AIM2, NLRC4, ASC, and caspase-1 were observed in patients with AOSD when compared with HC, while NLRP1 and NLRP3 showed no change in AOSD samples. In addition, CAI treatment could significantly reduce the levels of IL-1β, IL-6, and TNF-α secreted by AOSD PBMCs and inhibit AIM2 and NLRC4 inflammasomes activation in BMDMs. Conclusions: Increased levels of proinflammatory cytokines in AOSD might be associated with NLRC4 and AIM2 inflammasomes activation. CAI is likely to have the therapeutic potential for AOSD by inhibiting NLRC4 and AIM2 inflammasomes activation and reducing the proinflammatory cytokines and worthy of further investigation. These results provide new ideas for elucidating the pathogenesis of AOSD and providing specific targeted therapy. Key points • Significantly higher mRNA levels of AIM2 and NLRC4 inflammsome signaling were observed in AOSD patients compared with health controls, indicating that AIM2 and NLRC4 inflammsome activation might be related to the increased proinflammatory cytokines in AOSD. • CAI treatment markedly reduced the secretion levels of cytokines IL-1β, IL-6, and TNF-α in AOSD PBMCs and inhibited AIM2 and NLRC4 inflammasome activation. [ABSTRACT FROM AUTHOR]

Carboxyamidotriazole (CAI), originally developed as a non-cytotoxic anti-cancer drug, was shown to have anti-inflammatory activity according to recent studies in a number of animal models of inflammation. However, its mechanism of action has not been characterized. Therefore, the present study was performed to identify the anti-inflammatory action of CAI in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and to identify the signal transduction pathways involved. The in vitro results revealed that CAI had no direct effect on the activity of cyclooxygenase (COX), suggesting a different anti-inflammatory mechanism compared with that of COX-inhibiting non-steroidal anti-inflammatory drugs. Further investigation in RAW264.7 macrophages revealed that CAI decreased the production of nitric oxide via decreasing the LPS-stimulated expression of inducible nitric oxide synthase, and downregulated both mRNA and protein expression levels of the cytokines tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. CAI also significantly reduced the increased DNA-binding activity of nuclear factor (NF)-κB induced by LPS stimulation. With respect to the mechanisms involved on NF-κB activity, CAI exhibited suppression of the phosphorylation and degradation of the inhibitor of nuclear factor-κBα (IκB), and decreased the phosphorylation levels of the p65 subunit and its subsequent nuclear translocation. In addition, CAI significantly decreased the phosphorylated forms of p38, JNK and ERK, which were increased following LPS stimulation, while the total expression levels of p38, JNK and ERK remained unaltered. The results in the present study indicate that CAI alleviates the inflammatory responses of RAW 264.7 macrophages in response to LPS stimulation via attenuating the activation of NF-κB and MAPK signaling pathways and decreasing the levels of pro-inflammatory mediators. This offers a novel perspective for understanding the anti-inflammatory mechanism of CAI and suggests its potential use as a therapeutic treatment in inflammatory diseases with excessive macrophage activation. [ABSTRACT FROM AUTHOR]

Background and Purpose Pro-inflammatory cytokines are important in rheumatoid arthritis ( RA) and their production is mainly regulated by NF- κB and inflammasomes. Carboxyamidotriazole ( CAI) exhibits potent anti-inflammatory activities by decreasing cytokines. Here, we have investigated NACHT, LRR and PYD domains-containing protein ( NALP) inflammasomes in a rat model of RA and explored the therapeutic effects of CAI in this model and the involvement of NF- κB and inflammasomes in the actions of CAI. Experimental Approach The anti-arthritic effects of CAI were assessed in the adjuvant arthritis ( AA) model in rats, using radiological and histological techniques. NALP1 and NALP3 inflammasomes, NF- κB pathway and pro-inflammatory cytokines levels were measured with Western blots, immunohistochemistry and ELISA. Key Results CAI decreased the arthritis index, improved radiological and histological changes, and reduced synovial IL-1 β, IL-6, IL-18 and TNF- α levels in rats with AA. Compared with normal rats, the 70 kDa NALP1 isoform was up-regulated, NALP3 was down-regulated, and levels of the 165 kDa NALP1 isoform and the adaptor protein ASC were unchanged in synovial tissue from AA rats. CAI reduced the 70 kDa NALP1 isoform and restored NALP3 levels in AA rats; CAI inhibited caspase-1 activation in AA synovial tissue, but not its enzymic activity in vitro. In addition, CAI reduced expression of p65 NF- κB subunit and IκBα phosphorylation and degradation in AA rats. Conclusion and Implications NALP1 inflammasomes were activated in synovial tissues from AA rats and appeared to be a novel therapeutic target for RA. CAI could have therapeutic value in RA by inhibiting activation of NF- κB and NALP1 inflammasomes and by decreasing pro-inflammatory cytokines. [ABSTRACT FROM AUTHOR]

Background: Cancer immunotherapy has generated significant excitement, mainly as a result of the development of immune checkpoint inhibitors. The blockade of PD-1 or its ligand with antibodies has resulted in impressive clinical efficacy. However, a subset of patients does not respond to biologic therapeutics, and another subset suffers from severe immune-related adverse events in certain cases. The modulation of the immune system with small molecules might yield surprising benefits. Methods: CD8+ cells were obtained through a magnetic cell sorting system (MACS), and their capabilities for IFN-γ release and PD-1 expression were analyzed. The in vitro effects of drugs were studied in a coculture system of tumor cells and activated CD8+ cells. We further isolated the primary tumor cells in tumor-bearing mice treated with CAI, DMF, 1-MT or a combination (CAI and DMF/CAI and 1-MT) and analyzed the percentages of CD8+ T cells and PD-1+CD8+ T cells among TILs. The selective anti-tumor immune reactions of the two drug combinations were confirmed in a coculture system consisting of B16-OVA cells and OVA-specific CTLs derived from OT-1 transgenic mice. The anti-tumor effects of the single drugs or combined therapies were assessed according to their capability to slow tumor growth and extend the life span of tumor-bearing mice, and they were compared with the effects of PD-1 antibody. Results: CAI increased IFN-γ release from activated T cells, which might strengthen the anti-proliferative and anti-metastatic effects on cancer cells. However, CAI also stimulated IDO1-Kyn metabolic circuitry in the tumor microenvironment and facilitated tumor cell immune evasion. Combining CAI with 1-MT or DMF disrupted PD-1 expression and promoted IFN-γ production in CD8+ T cells, and it also increased T lymphocyte infiltration in the tumor microenvironment, inhibited tumor growth and prolonged the life spans of tumor-bearing mice. Conclusion: Inhibitors of the IDO1-Kyn-AhR pathway could abolish the negative effects of CAI on CD8+ T cells and result in complementary and beneficial anti-tumor immune effects. The combination of CAI with 1-MT or DMF greatly augmented the ability of CD8+ T cells to kill malignant cells and showed a strong anti-cancer capability that was superior to that of either of the single agents was is comparable with that of anti-PD-1 antibody. The combinations of small molecules utilized in this study may serve as valuable new immunotherapy strategies for cancer treatment. [ABSTRACT FROM AUTHOR]