Identification of Azalamellarin N as a Pyroptosis Inhibitor.

Pyroptosis is a form of regulated cell death that promotes inflammation; it attracts much attention because its dysregulation leads to various inflammatory diseases. To help explore the precise mechanisms by which pyroptosis is regulated, in this study, we searched for chemical compounds that inhibit pyroptosis. From our original compound library, we identified azalamellarin N (AZL-N), a hexacyclic pyrrole alkaloid, as an inhibitor of pyroptosis induced by R837 (also called imiquimod), which is an agonist of the intracellular multiprotein complex nucleotide-binding and oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome. However, whereas the effect of AZL-N on R837-induced pyroptosis was relatively weak, AZL-N strongly inhibited pyroptosis induced by extracellular ATP or nigericin, which are different types of NLRP3 inflammasome agonists. This was in contrast with the results that MCC950, a well-established NLRP3 inhibitor, consistently inhibited pyroptosis irrespective of the type of stimulus. We also found that AZL-N inhibited activation of caspase-1 and apoptosis-associated speck-like proteins containing a caspase activation and recruitment domain (ASC), which are components of the NLRP3 inflammasome. Analysis of the structure-activity relationship revealed that a lactam ring of AZL-N, which has been shown to contribute to the strong binding of AZL-N to its known target protein kinases, is required for its inhibitory effects on pyroptosis. These results suggest that AZL-N inhibits pyroptosis by targeting molecule(s), which may be protein kinase(s), that act upstream of NLRP3 inflammasome activation, rather than by directly targeting the components of the NLRP3 inflammasome. Further identification and analysis of target molecule(s) of AZL-N will shed light on the regulatory mechanisms of pyroptosis, particularly those depending on proinflammatory stimuli.

Immunologic parameters as significant prognostic factors in lung cancer.

Immunologic prognostic factors in lung cancer have not been fully clarified. We report the results of a prospective study undertaken to clarify the correlation between various cellular immunologic parameters and the survival of lung cancer patients. A total of 287 lung cancer patients were enrolled in this study. Representative in vitro cellular immune activities including lymphoblastogenesis and natural killer cell activities, in addition to the percentage of main lymphocyte subsets (CD3, CD4, CD8, HLA-DR, and Fc gamma R III on T cells) in the peripheral blood were evaluated before the initiation of therapy. The immune factors that influence the prognosis were analyzed by the log rank test and a multivariate analysis using the Cox proportional hazards model. Univariate analysis of the survival curves revealed a significant difference with regard to disease stage (P<0.0001), age (P=0.007), gender (P=0.0037), and HLA-DR (%) (P=0.048), when all the non-small cell lung cancer (NSCLC) patients (n=257) were analyzed together. This analysis, based on the histologic type, revealed that HLA-DR (%) was a significant predictor of survival in squamous cell carcinoma (P=0.0013) and small cell carcinoma (P=0.0025). A decreased CD4/CD8 ratio in small cell carcinoma (P=0.0062) and male gender in adenocarcinoma (P=0.0086) were factors associated with a worse prognosis. Multivariate analysis identified a significant correlation between survival and disease stage (P<0.0001) and gender (P=0.0243) in adenocarcinoma, disease stage (P<0.0001), age (P=0.0436) and HLA-DR (%) (P=0.0142) in squamous cell carcinoma, and HLA-DR (%) (P=0.0212) and CD4/CD8 (P=0.0112) in small cell carcinoma, suggesting independent prognostic significance. A variety of immunologic indices have prognostic significance for the different types of lung cancer. Among these, the HLA-DR (%) in the peripheral blood is the most reliable factor for squamous cell carcinoma and small cell carcinoma.