Monocarboxylate transporter 4 facilitates Mycobacterium tuberculosis survival through NF-κB p65-mediated interleukin-10 production.

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (Mtb) infection, with the highest single-cause mortality. Monocarboxylate transporter 4 (Mct4) transports intracellular lactate outside, but its role in regulating host immune response against Mtb infection remains unknown. Mct4 expression was upregulated in Mtb-infected macrophages and in patients with TB. Mct4 silencing/deficiency significantly decreased Mtb survival in macrophages and in lungs and spleens of mice, while Mct4 overexpression facilitated Mtb survival in macrophages. Furthermore, Mct4 promoted intracellular lactate transport, nuclear factor κB (NF-κB) p65 activation, and interleukin-10 (IL-10) production upon Mtb infection. Mechanistically, IL-10 silencing and IL-10-neutralizing antibody blocked Mct4 overexpressing increased Mtb survival. Replenishing lactate and NF-κB p65 inhibitor JSH23 treatment could inhibit Mct4 overexpressing increased NF-κB p65 activation, IL-10 production, and Mtb survival in macrophages. This study demonstrates that Mct4 promotes Mtb survival through restricting intracellular lactate accumulation to promote NF-κB p65-mediated IL-10 production and suggests Mct4-NF-κB p65-IL-10 axis a potential target for TB treatment.

A study of the evolutionary game of carbon offset involving tourism stakeholders under incentive and constraint mechanisms.

Tourism carbon offsetting is a crucial pathway to achieving peak carbon and carbon neutrality in the tourism industry. Accurately grasping the collaborative evolutionary mechanisms among local governments, tourism enterprises, and tourists is key to promoting the implementation of tourism carbon offsetting. By constructing an evolutionary game model involving local governments, tourism enterprises, and tourists in carbon offsetting, this study uses MATLAB to simulate the evolutionary stable strategies under various conditions. Additionally, it dynamically simulates the collaborative strategies of the three parties under the influence of local government incentive and constraint mechanisms. The results indicate that under strong governmental constraint mechanisms, there is a promotion of active participation in carbon offsetting by local governments, tourism enterprises, and tourists. Incentive policies at certain levels also play a positive guiding role. As incentives increase, local subsidies and intervention costs also rise, leading to an evolution towards less enthusiastic participation among the three parties. Appropriately balanced government incentives and penalties are beneficial in achieving an equilibrium of benefits among multiple stakeholders involved in carbon offsetting, thus helping to attain carbon neutrality goals.

Viperin inhibits interferon-γ production to promote Mycobacterium tuberculosis survival by disrupting TBK1-IKKε-IRF3-axis and JAK-STAT signaling.

OBJECTIVES AND DESIGN: As an interferon-inducible protein, Viperin has broad-spectrum antiviral effects and regulation of host immune responses. We aim to investigate how Viperin regulates interferon-γ (IFN-γ) production in macrophages to control Mycobacterium tuberculosis (Mtb) infection. METHODS: We use Viperin deficient bone-marrow-derived macrophage (BMDM) to investigate the effects and machines of Viperin on Mtb infection. RESULTS: Viperin inhibited IFN-γ production in macrophages and in the lung of mice to promote Mtb survival. Further insight into the mechanisms of Viperin-mediated regulation of IFN-γ production revealed the role of TANK-binding kinase 1 (TBK1), the TAK1-dependent inhibition of NF-kappa B kinase-epsilon (IKKε), and interferon regulatory factor 3 (IRF3). Inhibition of the TBK1-IKKε-IRF3 axis restored IFN-γ production reduced by Viperin knockout in BMDM and suppressed intracellular Mtb survival. Moreover, Viperin deficiency activated the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, which promoted IFN-γ production and inhibited Mtb infection in BMDM. Additionally, a combination of the anti-TB drug INH treatment in the absence of Viperin resulted in further IFN-γ production and anti-TB effect. CONCLUSIONS: This study highlights the involvement of TBK1-IKKε-IRF3 axis and JAK-STAT signaling pathways in Viperin-suppressed IFN-γ production in Mtb infected macrophages, and identifies a novel mechanism of Viperin on negatively regulating host immune response to Mtb infection.

Viperin deficiency promotes dendritic cell activation and function via NF-kappaB activation during Mycobacterium tuberculosis infection.

OBJECTIVES AND DESIGN: Dendritic cells (DCs) are one of the key immune cells in bridging innate and adaptive immune response against Mycobacterium tuberculosis (Mtb) infection. Interferons (IFNs) play important roles in regulating DC activation and function. Virus-inhibitory protein, endoplasmic reticulum-associated, interferon-inducible (Viperin) is one of the important IFN-stimulated genes (ISGs), and elicits host defense against infection. METHODS: We investigated the effects and mechanisms of Viperin on DC activation and function using Viperin deficient bone marrow-derived dendritic cells (BMDCs) during Mtb infection. RESULTS: Viperin deficiency enhanced phagocytic activity and increased clearance of Mtb in DCs, produced higher abundance of NO, cytokine including interleukin-12 (IL-12), Tumor necrosis factor-α (TNF-α), IL-1ß, IL-6 and chemokine including CXCL1, CXCL2 and CXCL10, elevated MHC I, MHC II and co-stimulatory molecules expression, and enhanced CD4+ and CD8+ T cell responses. Mechanistically, Viperin deficiency promoted DC activation and function through NF-κB p65 activation. NF-κB p65 inhibitor prevented cytokine and chemokine production, and co-stimulatory molecules expression promoted by Viperin deficiency. CONCLUSIONS: These results suggest that Mtb induced Viperin expression could impair the activation of host defense function of DCs and DC-T cell cross talk during Mtb infection. This research may provide a potential target for future HDT in TB therapy.

GSK-3α/ß Activity Negatively Regulates MMP-1/9 Expression to Suppress Mycobacterium tuberculosis Infection.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection is the deadliest infectious disease and a global health problem. Macrophages (Mφs) and neutrophils that can phagocytose Mtb represent the first line of immune response to infection. Glycogen synthase kinase-3α/ß (GSK-3α/ß) represents a regulatory switch in host immune responses. However, the efficacy and molecular mechanisms of how GSK-3α/ß interacts with Mtb infection in Mφs remain undefined. Here, we demonstrated that Mtb infection downregulated GSK-3α/ß activity and promoted matrix metalloproteinase-1 (MMP-1) and MMP-9 expressions in Mφs derived from acute monocytic human leukemia THP-1 cells (THP-1-Mφs). We confirmed the upregulation of MMP-9 expression in tissues of TB patients compared with patients of chronic inflammation (CI). In THP-1-Mφs and C57BL/6 mice, GSK-3α/ß inhibitor SB216763 significantly increased MMP-1/9 production and facilitated Mtb load, while MMP inhibitors blocked MMP-1/9 expression and Mtb infection. Consistently, GSK-3α/ß silencing significantly increased MMP-1/9 expression and Mtb infection, while overexpression of GSK-3α/ß and constitutive activated GSK-3α/ß mutants significantly reduced MMP-1/9 expression and Mtb infection in THP-1-Mφs. MMP-1/9 silencing reduced Mtb infection, while overexpression of MMP-1/9 promoted Mtb infection in THP-1-Mφs. We further found that GSK-3α/ß inhibition increased Mtb infection and MMP-1/9 expression was blocked by ERK1/2 inhibitor. Additionally, we showed that protein kinase C-δ (PKC-δ) and mammalian target of rapamycin (mTOR) reduced GSK-3α/ß activity and promoted MMP-1/9 production in Mtb-infected THP-1-Mφs. In conclusion, this study suggests that PKC-δ-mTOR axis suppresses GSK-3α/ß activation with acceleration of MMP-1/9 expression through phospho-ERK1/2. These results reveal a novel immune escape mechanism of Mtb and a novel crosstalk between these critical signaling pathways in anti-TB immunity.