Causal relationship between gut microbiota and tuberculosis: a bidirectional two-sample Mendelian randomization analysis.

BACKGROUND: Growing evidence from observational studies and clinical trials suggests that the gut microbiota is associated with tuberculosis (TB). However, it is unclear whether any causal relationship exists between them and whether causality is bidirectional. METHODS: A bidirectional two-sample Mendelian randomization (MR) analysis was performed. The genome-wide association study (GWAS) summary statistics of gut microbiota were obtained from the MiBioGen consortium, while the GWAS summary statistics of TB and its specific phenotypes [respiratory tuberculosis (RTB) and extrapulmonary tuberculosis (EPTB)] were retrieved from the UK Biobank and the FinnGen consortium. And 195 bacterial taxa from phylum to genus were analyzed. Inverse variance weighted (IVW), MR-Egger regression, maximum likelihood (ML), weighted median, and weighted mode methods were applied to the MR analysis. The robustness of causal estimation was tested using the heterogeneity test, horizontal pleiotropy test, and leave-one-out method. RESULTS: In the UK Biobank database, we found that 11 bacterial taxa had potential causal effects on TB. Three bacterial taxa genus.Akkermansia, family.Verrucomicrobiacea, order.Verrucomicrobiales were validated in the FinnGen database. Based on the results in the FinnGen database, the present study found significant differences in the characteristics of gut microbial distribution between RTB and EPTB. Four bacterial taxa genus.LachnospiraceaeUCG010, genus.Parabacteroides, genus.RuminococcaceaeUCG011, and order.Bacillales were common traits in relation to both RTB and TB, among which order.Bacillales showed a protective effect. Additionally, family.Bacteroidacea and genus.Bacteroides were identified as common traits in relation to both EPTB and TB, positively associating with a higher risk of EPTB. In reverse MR analysis, no causal association was identified. No significant heterogeneity of instrumental variables (IVs) or horizontal pleiotropy was found. CONCLUSION: Our study supports a one-way causal relationship between gut microbiota and TB, with gut microbiota having a causal effect on TB. The identification of characteristic gut microbiota provides scientific insights for the potential application of the gut microbiota as a preventive, diagnostic, and therapeutic tool for TB.

The effects of meteorological factors and air pollutants on the incidence of tuberculosis in people living with HIV/AIDS in subtropical Guangxi, China.

BACKGROUND: Previous studies have shown the association between tuberculosis (TB) and meteorological factors/air pollutants. However, little information is available for people living with HIV/AIDS (PLWHA), who are highly susceptible to TB. METHOD: Data regarding TB cases in PLWHA from 2014 to2020 were collected from the HIV antiviral therapy cohort in Guangxi, China. Meteorological and air pollutants data for the same period were obtained from the China Meteorological Science Data Sharing Service Network and Department of Ecology and Environment of Guangxi. A distribution lag non-linear model (DLNM) was used to evaluate the effects of meteorological factors and air pollutant exposure on the risk of TB in PLWHA. RESULTS: A total of 2087 new or re-active TB cases were collected, which had a significant seasonal and periodic distribution. Compared with the median values, the maximum cumulative relative risk (RR) for TB in PLWHA was 0.663 (95% confidence interval [CI]: 0.507-0.866, lag 4 weeks) for a 5-unit increase in temperature, and 1.478 (95% CI: 1.116-1.957, lag 4 weeks) for a 2-unit increase in precipitation. However, neither wind speed nor PM10 had a significant cumulative lag effect. Extreme analysis demonstrated that the hot effect (RR = 0.638, 95%CI: 0.425-0.958, lag 4 weeks), the rainy effect (RR = 0.285, 95%CI: 0.135-0.599, lag 4 weeks), and the rainless effect (RR = 0.552, 95%CI: 0.322-0.947, lag 4 weeks) reduced the risk of TB. Furthermore, in the CD4(+) T cells < 200 cells/µL subgroup, temperature, precipitation, and PM10 had a significant hysteretic effect on TB incidence, while temperature and precipitation had a significant cumulative lag effect. However, these effects were not observed in the CD4(+) T cells ≥ 200 cells/µL subgroup. CONCLUSION: For PLWHA in subtropical Guangxi, temperature and precipitation had a significant cumulative effect on TB incidence among PLWHA, while air pollutants had little effect. Moreover, the influence of meteorological factors on the incidence of TB also depends on the immune status of PLWHA.

LncRNA ANRIL Expression and ANRIL Gene Polymorphisms Contribute to the Risk of Ischemic Stroke in the Chinese Han Population.

The aim of the present study was to explore the role of lncRNA ANRIL in the pathogenesis of ischemic stroke (IS) and coronary artery disease (CAD) and to determine the association between ANRIL variants and the genetic susceptibility of IS and CAD in the Chinese Han population. A genetic association study including 550 IS patients, 550 CAD patients, and 550 healthy controls was conducted. The expression levels of lncRNA ANRIL, CDKN2A, and CDKN2B were detected using qRT-PCR. Genotyping was performed by Sequenom MassARRAY on an Agena platform. Our study showed that IS patients had an increased lncRNA ANRIL expression (P = 0.002) and a decreased CDKN2A expression (P < 0.001) compared with normal controls. A significant difference with regard to the genotype distribution of rs2383207 was found between male IS patients and controls (P = 0.011). The minor allele of rs2383207 significantly increased the IS risk under a recessive model (OR = 1.52, 95% CI = 1.05-2.21, P = 0.027). The minor allele of rs1333049 was significantly associated with the risk of IS among the male patients under a recessive model (OR = 1.56, 95% CI = 1.04-2.35, P = 0.031). However, no significant association was found between the ANRIL variants and the risk of CAD (all P > 0.050). In addition, we found a decreased lncRNA ANRIL expression in IS patients who carried the GG genotype of rs1333049 compared with IS patients who carried the CC or CG genotype (P = 0.041). In summary, we found that IS patients had an increased lncRNA ANRIL expression and a decreased CDKN2A expression compared with the controls, which might play an impellent role in pathological processes of IS. The ANRIL variants rs2383207 and rs1333049 were significantly associated with the risk of IS among males but not females in the Chinese Han population.

Mycothiol peroxidase MPx protects Corynebacterium glutamicum against acid stress by scavenging ROS.

OBJECTIVES: To investigate mycothiol peroxidase (MPx) of Corynebacterium glutamicum that is a novel CysGPx family peroxidase using both the mycoredoxin and thioredoxin reducing systems as proton donors for peroxide detoxification and may be involved in the relief of acid stress. RESULTS: A Δmpx mutant exhibited significantly decreased resistance to acid stress and markedly increased accumulation of reactive oxygen species (ROS) and protein carbonylation levels in vivo. Over-expression of mpx increased the resistance of C. glutamicum to acid stress by reducing ROS accumulation. The stress-responsive extracytoplasmic function-sigma (ECF-σ) factor, SigH, mediated acid-induced expression of mpx in the wild-type under acid conditions, which in turn directly contributed to tolerance to acid stress. CONCLUSION: MPx is essential for combating acid stress by reducing intracellular ROS levels induced by acid stress in C. glutamicum, which adds a new dimension to the general physiological functions of CysGPx.

Activation of the JNK/COX-2/HIF-1α axis promotes M1 macrophage via glycolytic shift in HIV-1 infection.

Chronic inflammation is recognized as a major risk factor for the severity of HIV infection. Whether metabolism reprogramming of macrophages caused by HIV-1 is related to chronic inflammatory activation, especially M1 polarization of macrophages, is inconclusive. Here, we show that HIV-1 infection induces M1 polarization and enhanced glycolysis in macrophages. Blockade of glycolysis inhibits M1 polarization of macrophages, indicating that HIV-1-induced M1 polarization is supported by enhanced glycolysis. Moreover, we find that this immunometabolic adaptation is dependent on hypoxia-inducible factor 1α (HIF-1α), a strong inducer of glycolysis. HIF-1α-target genes, including HK2, PDK1, and LDHA, are also involved in this process. Further research discovers that COX-2 regulates HIF-1α-dependent glycolysis. However, the elevated expression of COX-2, enhanced glycolysis, and M1 polarization of macrophages could be reversed by inactivation of JNK in the context of HIV-1 infection. Our study mechanistically elucidates that the JNK/COX-2/HIF-1α axis is activated to strengthen glycolysis, thereby promoting M1 polarization in macrophages in HIV-1 infection, providing a new idea for resolving chronic inflammation in clinical AIDS patients.

The global burden of cardiovascular diseases and type 2 diabetes attributable to low physical activity, 1990-2019: an analysis from the global burden of disease study.

Background: Cardiovascular diseases (CVD) and type 2 diabetes (T2D) account for the majority of the burden of noncommunicable disease caused by low physical activity (LPA). In order to inform future interventions, this study aims to assess the burden and trends in mortality and disability-adjusted life years (DALYs) of CVD and T2D attributable to LPA by year, location, sex, and age from 1990 to 2019. Methods: Mortality, DALYs, and their age-standardised rates (ASMR, ASDR) for CVD and T2D attributable to LPA were retrieved from Global Burden of Disease (GBD) 2019. The estimated annual percentage changes (EAPCs) were calculated using linear regression model to describe the trend over time. Results: From 1990 to 2019, the number of deaths caused by both CVD and T2D due to LPA increased significantly globally. However, the overall ASMR and ASDR for CVD declined over this same period [EAPC for ASMR (CVD) = -1.44 (95% CI: -1.50-1.38), EAPC for ASDR (CVD) = -1.30 (95% CI: -1.35 to -1.25)]. In terms of disparities, ASMR (CVD) and ASDR (CVD) in North Africa and the Middle East were consistently higher than the global average; also, the sex difference in ASMR was greatest in Central Asia. ASMR among people aged 25-44 in high Socio-Demographic Index (SDI) region has increased significantly over the past three decades. ASMR (T2D) due to LPA showed an increasing trend year by year, with EAPC = 0.26 (95% CI: 0.13-0.39), and this rate increased faster in males than in females. Consistent with cardiovascular diseases, ASMR of type 2 diabetes attributable to LPA increased among people aged 25-44, while decreased in other age groups in high SDI region. Conclusion: Interventions targeting LPA are warranted in controlling the burden of cardiovascular diseases and type 2 diabetes. Countries should adapt strategies to their local contexts, considering the sex and age differences among their populations. The 25-44 age group should be given special attention to prevent the disease burden from worsening among younger people.

Functional comparison of methionine sulphoxide reductase A and B in Corynebacterium glutamicum.

Methionine sulphoxide reductases (Msr) are able to reduce methionine sulfoxide to methionine and protect bacteria against reactive oxygen species (ROS). Many organisms express both methionine sulphoxide reductase A (MsrA), specific for methionine-S-sulfoxide and methionine sulphoxide reductase B (MsrB), active against methionine-R-sulfoxide. Corynebacterium glutamicum expresses MsrA, the function of which has been well defined; however, the function of MsrB has not been studied. Whether MsrB and MsrA play an equally important role in the antioxidant process is also poorly understood. In this study, we identified MsrB encoded by ncgl1823 in C. glutamicum, investigated its function and made a comparison with MsrA. The msrB gene showed a slight effect on utilizing methionine sulfoxide (MetO) as the sole Met source; however, the survival rates showed no sensitivity to oxidants. MsrB showed catalytic activity using thioredoxin/thioredoxin reductase (Trx/TrxR) reducing system as electron donors, but independent from the mycoredoxin 1/mycothione reductase/mycothiol (Mrx1/Mtr/MSH) system. Therefore, MsrB plays a limited role in resisting oxidative stress and it could reduce MetO to Met by the Trx/TrxR reducing system, which is useful for expanding the understanding of the functions of Msr in this important industrial microbe.

ZntR positively regulates T6SS4 expression in Yersinia pseudotuberculosis.

The type VI secretion system (T6SS) is a widespread and versatile protein secretion system found in most Gram-negative bacteria. Studies of T6SS have mainly focused on its role in virulence toward host cells and inter-bacterial interactions, but studies have also shown that T6SS4 in Yersinia pseudotuberculosis participates in the acquisition of zinc ions to alleviate the accumulation of hydroxyl radicals induced by multiple stressors. Here, by comparing the gene expression patterns of wild-type and zntR mutant Y. pseudotuberculosis cells using RNA-seq analysis, T6SS4 and 17 other biological processes were found to be regulated by ZntR. T6SS4 was positively regulated by ZntR in Y. pseudotuberculosis, and further investigation demonstrated that ZntR regulates T6SS4 by directly binding to its promoter region. T6SS4 expression is regulated by zinc via ZntR, which maintains intracellular zinc homeostasis and controls the concentration of reactive oxygen species to prevent bacterial death under oxidative stress. This study provides new insights into the regulation of T6SS4 by a zinc-dependent transcriptional regulator, and it provides a foundation for further investigation of the mechanism of zinc transport by T6SS.

A starvation-induced regulator, RovM, acts as a switch for planktonic/biofilm state transition in Yersinia pseudotuberculosis.

The transition between the planktonic state and the biofilm-associated state is a key developmental decision for pathogenic bacteria. Biofilm formation by Yersinia pestis is regulated by hmsHFRS genes (ß-1, 6-N-acetyl-D-glucosamine synthesis operon) in its flea vector and in vitro. However, the mechanism of biofilm formation in Yersinia pseudotuberculosis remains elusive. In this study, we demonstrate that the LysR-type regulator RovM inversely regulates biofilm formation and motility in Y. pseudotuberculosis by acting as a transcriptional regulator of these two functions. RovM is strongly induced during growth in minimal media but strongly repressed in complex media. On one hand, RovM enhances bacterial motility by activating the expression of FlhDC, the master regulator of flagellar genes, via the recognition of an operator upstream of the flhDC promoter. On the other hand, RovM represses ß-GlcNAc production under nutrition-limited conditions, negatively regulating hmsHFRS expression by directly binding to the -35 element of its promoter. Compared to wild-type bacteria, the rovM mutant established denser biofilms and caused more extensive mortality in mice and silkworm larvae. These results indicate that RovM acts as a molecular switch to coordinate the expression of genes involved in biofilm formation and motility in response to the availability of nutrients.

The Type VI Secretion System Engages a Redox-Regulated Dual-Functional Heme Transporter for Zinc Acquisition.

The type VI secretion system was recently reported to be involved in zinc acquisition, but the underlying mechanism remains unclear. Here, we report that Burkholderia thailandensis T6SS4 is involved in zinc acquisition via secretion of a zinc-scavenging protein, TseZ, that interacts with the outer membrane heme transporter HmuR. We find that HmuR is a redox-regulated dual-functional transporter that transports heme iron under normal conditions but zinc upon sensing extracellular oxidative stress, triggered by formation of an intramolecular disulfide bond. Acting as the first line of defense against oxidative stress, HmuR not only guarantees an immediate response to the changing environment but also provides a fine-tuned mechanism that allows a gradual response to perceived stress. The T6SS/HmuR-mediated active zinc transport system is also involved in bacterial virulence and contact-independent bacterial competition. We describe a sophisticated bacterial zinc acquisition mechanism affording insights into the role of metal ion transport systems.