Methylprednisolone Promotes Mycobacterium smegmatis Survival in Macrophages through NF-κB/DUSP1 Pathway

Abstract

Background: Mycobacterium tuberculosis (M. tuberculosis) is the causative agent of tuberculosis. As an important component of host immunity, macrophages are not only the first line of defense against M. tuberculosis but also the parasitic site of M. tuberculosis in the host. Glucocorticoids can cause immunosuppression, which is considered to be one of the major risk factors for active tuberculosis, but the mechanism is unclear. Objective: To study the effect of methylprednisolone on the proliferation of mycobacteria in macrophages and try to find key molecules of this phenomenon. Methods: The macrophage line RAW264.7 infected by M. smegmatis was treated with methylprednisolone, and the intracellular bacterial CFU, Reactive Oxygen Species (ROS), cytokine secretion, autophagy, and apoptosis were measured. After the cells were treated with NF-κB inhibitor BAY 11-7082 and DUSP1 inhibitor BCI, respectively, the intracellular bacterial CFU, ROS, IL-6, and TNF-α secretion were detected. Results: After treatment with methylprednisolone, the CFU of intracellular bacteria increased, the level of ROS decreased, and the secretion of IL-6 and TNF-α decreased in infected macrophages. After BAY 11-7082 treatment, the CFU of M. smegmatis in macrophages increased, and the level of ROS production and the secretion of IL-6 by macrophages decreased. Transcriptome high-throughput sequencing and bioinformatics analysis suggested that DUSP1 was the key molecule in the above phenomenon. Western blot analysis confirmed that the expression level of DUSP1 was increased in the infected macrophages treated with methylprednisolone and BAY 11-7082, respectively. After BCI treatment, the level of ROS produced by infected macrophages increased, and the secretion of IL-6 increased. After the treatment of BCI combined with methylprednisolone or BAY 11-7082, the level of ROS produced and the secretion of IL-6 by macrophages were increased. Conclusion: methylprednisolone promotes the proliferation of mycobacteria in macrophages by suppressing cellular ROS production and IL-6 secretion through down-regulating NF-κB and up-regulating DUSP1 expression. BCI, an inhibitor of DUSP1, can reduce the level of DUSP1 in the infected macrophages and inhibit the proliferation of intracellular mycobacteria by promoting cellular ROS production and IL-6 secretion. Therefore, BCI may become a new molecule for host-directed therapy of tuberculosis, as well as a new strategy for the prevention of tuberculosis when treated with glucocorticoids.

Chronic TNF exposure induces glucocorticoid‐like immunosuppression in the alveolar macrophages of aged mice that enhances their susceptibility to pneumonia

“…Notably, the increased expression in Dusp1 and Ptprs has been shown to occur due to many chronic inflammatory diseases, including cancer, rheumatoid arthritis, and ulcerative colitis (Berillo et al., 2022 ; Davis et al., 2018 ; Hendriks & Pulido, 2013 ; Khadir et al., 2018 ; Liu et al., 2019 ; Muise et al., 2007 ; Xu et al., 2015 ). Yet the deletion of Dusp1 in animal models enhanced susceptibility to pathogens, including Mycobacterium tuberculosis , Chlamydophila pneumonia, Staphylococcus aureus , and Escherichia coli (Cheung et al., 2009 ; Frazier et al., 2009 ; Gräb et al., 2019 ; Hammer et al., 2010 ; Kim et al., 2012 ; Li et al., 2023 ; Rodriguez et al., 2010 ; Wang et al., 2007 ; Zhao et al., 2006 ). Thus, the negative regulators, Dusp1 and Ptprs , help maintain a level of inflammation essential for the development of an appropriate antimicrobial response and whose perturbation by deletion is too far‐reaching.…”

Dual-Specificity Phosphatases in Regulation of Tumor-Associated Macrophage Activity

“…Regarding triple-negative cancer cells, these agents inhibited their growth and ability to migration [183]. It is currently unknown how BCIs affect tumor-associated macrophages, although BCIs are known to act on macrophages in models of chronic inflammation [184][185][186]. For instance, the pharmacological inhibition of DUSP6 attenuated LPS-induced inflammatory mediators and ROS production in macrophage cells through the inhibition of the NF-κB pathway and the activation of the NF-E2-related factor 2 (Nrf2) signaling axis [184].…”

“…BCI suppressed differentiation-related signaling pathways and reduced the differentiation of bone marrow cells into macrophages through the inhibition of DUSP6, which prevented myocardial fibrosis after infarction [185]. BCI reduced DUSP1 levels in infected macrophages and suppressed intracellular mycobacterial proliferation by stimulating cellular ROS production and IL-6 secretion [186].…”