Search

Tuberculosis (TB) is a zoonotic infectious disease caused by Mycobacterium tuberculosis (Mtb). Mtb is a typical intracellular parasite, and macrophages are its main host cells. NLRP3 inflammasome-mediated pyroptosis is a form of programmed cell death implicated in the clearance of pathogenic infections. The bidirectional regulatory effect of endoplasmic reticulum stress (ERS) plays a crucial role in determining cell survival and death. Whether ERS is involved in macrophage pyroptosis with Mtb infection remains unclear. This article aims to explore the regulation of the NLRP3 inflammasome and pyroptosis by ERS in THP-1 macrophages infected with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). The results showed that BCG infection induced THP-1 macrophage ERS, NLRP3 inflammasome activation and pyroptosis, which was inhibited by ERS inhibitor TUDCA. NLRP3 inhibitor MCC950 inhibited THP-1 macrophage NLRP3 inflammasome activation and pyroptosis caused by BCG infection. Compared with specific Caspase-1 inhibitor VX-765, pan-Caspase inhibitor Z-VAD-FMK showed a more significant inhibitory effect on BCG infection-induced pyroptosis of THP-1 macrophages. Taken together, this study demonstrates that ERS mediated NLRP3 inflammasome activation and pyroptosis after BCG infection of THP-1 macrophages, and that BCG infection of THP-1 macrophages induces pyroptosis through canonical and noncanonical pathways.

Background: Type II alveolar epithelial cell (AEC II), in addition to its roles in maintaining lung homeostasis, takes an active role in inflammatory response during acute lung injury (ALI). Ca 2+ /calmodulin-dependent protein kinase IV (CaMK4) activated by Ca 2+ /calmodulin signaling, has been implicated in immune responses. This study was to investigate the roles of CaMK4 in the development of ALI and the underlying mechanisms., Methods: CaMK4 inhibitor KN-93 was used to investigate the effects of CaMK4 on NLRP3 inflammasome activation. The effects of KN-93 on disease development of lipopolysaccharide (LPS)-induced ALI were also evaluated. The role of CaMK4 on NLRP3 inflammasome activation was explored in human AEC II cell line A549 using KN-93 or CaMK4 siRNA. NLRP3 inflammasome activation was measured by histology immunofluorescence and Western blot. IL-1β and IL-18 were measured by ELISA., Results: Phosphorylation of CaMK4 and the expression of NLRP3 and Caspase-1 p20 were increased in the lungs of LPS-induced ALI mice, which was suppressed by KN-93 as measured by Western blot. Further, the activation of NLRP3 inflammasome was detected in AEC II from patients with acute respiratory distress syndrome (ARDS) and LPS-induced ALI mice. In vitro , inhibition or silencing CaMK4 in AEC II significantly inhibited NLRP3 inflammasome activation, resulting in reduced IL-1β production. The inhibition of NLRP3 inflammasome and decreased IL-1β/IL-18 production by KN-93 led to reduced inflammatory infiltration and ameliorated lung injury in LPS-induced ALI mice., Conclusion: CaMK4 controls the activation of NLRP3 inflammasome in AEC II during LPS-induced ALI. CaMK4 inhibition could be a novel therapeutic approach for the treatment of ALI., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhang, Li, Zhao, Zhou, Liao, Wu, Mo, Wang, Guo, Zhang, Yang and Huang.)

Despite rapid progress in the understanding of systemic lupus erythematosus (SLE), there is still an urgent need for novel and more effective interventions. Curcumin, a natural polyphenol compound, has been shown to be anti-inflammatory in various disorders. In this study, we investigated the potential therapeutic value of curcumin in SLE. Lupus-prone female MRL/lpr mice were treated with curcumin. The development and extent of nephritis were assessed by monitoring proteinuria and by histologic analysis. Serum anti-dsDNA levels were measured by enzyme-linked immunosorbent assay. Kidney samples were analyzed by Western blot. In vitro, mouse podocytes were used for investigation in the presence of mouse anti-dsDNA antibody-positive (anti-dsDNA+) serum. Curcumin treatment dramatically decreased proteinuria and renal inflammation. Serum anti-dsDNA levels and spleen size were also reduced by curcumin. In addition, curcumin reduced NLRP3 inflammasome activation in lupus-prone mice. In vitro, curcumin significantly inhibited anti-dsDNA+ serum induced expression of NLRP3 inflammasome in podocytes. Overall, these data demonstrate the potential use of curcumin in SLE treatment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Pyroptosis is a host immune strategy to defend against Mycobacterium tuberculosis (Mtb) infection. S100A4, a calcium-binding protein that plays an important role in promoting cancer progression as well as the pathophysiological development of various non-tumor diseases, has not been explored in Mtb-infected hosts. In this study, transcriptome analysis of the peripheral blood of patients with pulmonary tuberculosis (PTB) revealed that S100A4 and GSDMD were significantly up-regulated in PTB patients' peripheral blood. Furthermore, there was a positive correlation between the expression of GSDMD and S100A4. KEGG pathway enrichment analysis showed that differentially expressed genes between PTB patients and healthy controls were significantly related to inflammation, such as the NOD-like receptor signaling pathway and NF-κB signaling pathway. To investigate the regulatory effects of S100A4 on macrophage pyroptosis, THP-1 macrophages infected with Bacillus Calmette-Guérin (BCG) were pre-treated with exogenous S100A4, S100A4 inhibitor or si-S100A4. This research study has shown that S100A4 promotes the pyroptosis of THP-1 macrophages caused by BCG infection and activates NLRP3 inflammasome and NF-κB signaling pathways, which can be inhibited by knockdown or inhibition of S100A4. In addition, inhibition of NF-κB or NLRP3 blocks the promotion effect of S100A4 on BCG-induced pyroptosis of THP-1 macrophages. In conclusion, S100A4 activates the NF-κB/NLRP3 inflammasome signaling pathway to promote macrophage pyroptosis induced by Mtb infection. These data provide new insights into how S100A4 affects Mtb-induced macrophage pyroptosis. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Endoplasmic Reticulum Stress Mediated NLRP3 Inflammasome Activation and Pyroptosis in THP-1 Macrophages Infected with Bacillus Calmette-Guérin." The correction states that Lei Liu was not initially included as an author in the publication, but her contributions were significant in shortening the experiment time. After discussion with all authors, it was decided to add Lei Liu's name to the article. The correction does not affect the scientific conclusions of the study. The corrected author contributions statement is provided, and the original publication has been updated. [Extracted from the article]