Fatty acid metabolism in neutrophils promotes lung damage and bacterial replication during tuberculosis.

Mycobacterium tuberculosis (Mtb) infection induces a marked influx of neutrophils into the lungs, which intensifies the severity of tuberculosis (TB). The metabolic state of neutrophils significantly influences their functional response during inflammation and interaction with bacterial pathogens. However, the effect of Mtb infection on neutrophil metabolism and its consequent role in TB pathogenesis remain unclear. In this study, we examined the contribution of glycolysis and fatty acid metabolism on neutrophil responses to Mtb HN878 infection using ex-vivo assays and murine infection models. We discover that blocking glycolysis aggravates TB pathology, whereas inhibiting fatty acid oxidation (FAO) yields protective outcomes, including reduced weight loss, immunopathology, and bacterial burden in lung. Intriguingly, FAO inhibition preferentially disrupts the recruitment of a pathogen-permissive immature neutrophil population (Ly6Glo/dim), known to accumulate during TB. Targeting carnitine palmitoyl transferase 1a (Cpt1a)-a crucial enzyme in mitochondrial ß-oxidation-either through chemical or genetic methods impairs neutrophils' ability to migrate to infection sites while also enhancing their antimicrobial function. Our findings illuminate the critical influence of neutrophil immunometabolism in TB pathogenesis, suggesting that manipulating fatty acid metabolism presents a novel avenue for host-directed TB therapies by modulating neutrophil functions.

Altered hepatic metabolic landscape and insulin sensitivity in response to pulmonary tuberculosis.

Chronic inflammation triggers development of metabolic disease, and pulmonary tuberculosis (TB) generates chronic systemic inflammation. Whether TB induced-inflammation impacts metabolic organs and leads to metabolic disorder is ill defined. The liver is the master regulator of metabolism and to determine the impact of pulmonary TB on this organ we undertook an unbiased mRNA and protein analyses of the liver in mice with TB and reanalysed published data on human disease. Pulmonary TB led to upregulation of genes in the liver related to immune signalling and downregulation of genes encoding metabolic processes. In liver, IFN signalling pathway genes were upregulated and this was reflected in increased biochemical evidence of IFN signalling, including nuclear location of phosphorylated Stat-1 in hepatocytes. The liver also exhibited reduced expression of genes encoding the gluconeogenesis rate-limiting enzymes Pck1 and G6pc. Phosphorylation of CREB, a transcription factor controlling gluconeogenesis was drastically reduced in the livers of mice with pulmonary TB as was phosphorylation of other glucose metabolism-related kinases, including GSK3a, AMPK, and p42. In support of the upregulated IFN signalling being linked to the downregulated metabolic functions in the liver, we found suppression of gluconeogenic gene expression and reduced CREB phosphorylation in hepatocyte cell lines treated with interferons. The impact of reduced gluconeogenic gene expression in the liver was seen when infected mice were less able to convert pyruvate, a gluconeogenesis substrate, to the same extent as uninfected mice. Infected mice also showed evidence of reduced systemic and hepatic insulin sensitivity. Similarly, in humans with TB, we found that changes in a metabolite-based signature of insulin resistance correlates temporally with successful treatment of active TB and with progression to active TB following exposure. These data support the hypothesis that TB drives interferon-mediated alteration of hepatic metabolism resulting in reduced gluconeogenesis and drives systemic reduction of insulin sensitivity.

GRN Activates TNFR2 to Promote Macrophage M2 Polarization Aggravating Mycobacterium Tuberculosis Infection.

BACKGROUND: The polarization of macrophages plays a critical role in the immune response to infectious diseases, with M2 polarization shown to be particularly important in various pathological processes. However, the specific mechanisms of M2 macrophage polarization in Mycobacterium tuberculosis (Mtb) infection remain unclear. In particular, the roles of Granulin (GRN) and tumor necrosis factor receptor 2 (TNFR2) in the M2 polarization process have not been thoroughly studied. OBJECTIVE: To investigate the effect of macrophage M2 polarization on Mtb infection and the mechanism of GRN and TNFR2 in M2 polarization. METHODS: Forty patients with pulmonary tuberculosis (PTB) and 40 healthy volunteers were enrolled in this study, and peripheral blood samples were taken to detect the levels of TNFR2 and GRN mRNA by Quantitative Reverse Transcription Polymerase Chain Reaction (RT-qPCR); monocytes were isolated and then assessed by Flow Cytometry (FC) for M1 and M2 macrophage levels. To further validate the function of TNFR2 in macrophage polarization, we used interleukin 4 (IL-4) to induce mouse monocyte macrophages RAW264.7 to M2 polarized state. The expression of TNFR2 was detected by Western Blot and RT-qPCR. Next, we constructed a GRN knockdown plasmid and transfected it into IL-4-induced mouse monocyte macrophage RAW264.7, and detected the expression of TNFR2, M1 macrophage-associated factors tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), and interleukin 6 (IL-6), and the M2 macrophage-associated factors CD206, IL-10, and Arginase 1 (Arg1); Immunofluorescence staining was used to monitor the expression of CD86+ and CD206+, and FC was used to analyze the macrophage phenotype. Subsequently, immunoprecipitation was used to detect the binding role of GRN and TNFR2. Finally, the effects of GRN and TNFR2 in macrophage polarization were further explored by knocking down GRN and simultaneously overexpressing TNFR2 and observing the macrophage polarization status. RESULTS: The results of the study showed elevated expression of TNFR2 and GRN and predominance of M2 type in macrophages in PTB patients compared to healthy volunteers (p < 0.05). Moreover, TNFR2 was highly expressed in M2 macrophages (p < 0.05). Additionally, GRN knockdown was followed by elevated expression of M1 polarization markers TNF-α, iNOS and IL-6 (p < 0.05), decreased levels of M2 polarization-associated factors CD206, IL-10 and Arg1 (p < 0.05), and macrophage polarization towards M1. Subsequently, we found that GRN binds to TNFR2 and that GRN upregulates TNFR2 expression (p < 0.05). In addition, knockdown of GRN elevated M1 polarization marker expression, decreased M2 polarization marker expression, and increased M1 macrophages and decreased M2 macrophages, whereas concurrent overexpression of TNFR2 decreased M1 polarization marker expression, elevated M2 polarization marker expression, and decreased M1 macrophages and increased M2 macrophages. CONCLUSION: TNFR2 and GRN are highly expressed in PTB patients and GRN promotes macrophage M2 polarization by upregulating TNFR2 expression.

[Molecular markers of M. tuberculosis virulence in lung tissue (experimental study)]. / Molekulyarnye markery virulentnosti M. tuberculosis v tkani legkikh (eksperimental'noe issledovanie).

More than a quarter of the world's population is infected with Mycobacterium tuberculosis. However, only about 10% of those infected develop active TB. This indicates a key role for innate immunity in limiting M. tuberculosis replication. Most often, bacteria can regulate the expression of host-specific molecules and weaken host immunity. OBJECTIVE: To use a biological model, in order to determine significant molecular immunohistochemical markers characterizing the virulence of the "Buryat" and "Omsk" subtypes of the M. tuberculosis Beijing genotype in lung tissue. MATERIAL AND METHODS: Lung samples of the C57BL/6 male mice were obtained during experimental infection with M. tuberculosis strains: the reference laboratory strain H37Rv, multidrug-resistant clinical strains 396 (highly lethal and hypervirulent «Buryat¼ genotype Beijing 14717-15) and 6691 (low-lethal and low-virulent "Omsk" genotype Beijing 1071-32) on days 14, 21, 60 and 120. They were studied by histological and immunohistochemical methods. The relative areas of expression of IL-6, IL-12A, iNOS, and TNF-α in the lung tissue of model animals were established. RESULTS: A study of strain 396 showed that both disease progression and damage to lung tissue are associated with a highly reactive immune response and increased synthesis of iNOS and strain characteristics that block the production of TNF-α. On the contrary, for strain 6691 a low reactivity of the immune response was revealed, with statistically significantly lower values of the relative area of expression of NOS and TNF-α during all observation periods (days 14-120). All animals that survived to day 120 showed a similar morphological picture with differences in cytokine levels, indicating a nonlinear relationship between proinflammatory factors and the damage substratum. CONCLUSION: The progression of the disease and damage of lung tissue were associated with a highly reactive immune response and increased synthesis of iNOS, strain properties that block the TNF-α production. Thus, iNOS and TNF-α can act as molecular markers characterizing the virulence of the "Buryat" and "Omsk" subtypes of M. tuberculosis in lung tissue.

T cells exhaustion, inflammatory and cellular activity markers in PBMCs predict treatment outcome in pulmonary tuberculosis patients.

BACKGROUND: Pulmonary tuberculosis (PTB) is a well-known disease caused by Mycobacterium tuberculosis. Its pathogenesis is premised on evasion of the immune system and dampened immune cells activity. METHODS: Here, the transcription pattern of immune cells exhaustion, inflammatory, and cellular activity markers were examined in peripheral blood mononuclear cells (PBMCs) from PTB patients at various stages of treatment. PBMCs were isolated, and RNA extracted. cDNA synthesis was performed, then amplification of genes of interest. RESULTS: The T cell exhaustion markers (PD-L1, CTLA4, CD244 and LAG3) showed varied levels of expressions when comparing 0 T and 1 T to the other treatment phases, suggesting their potential roles as markers for monitoring TB treatment. IL-2, IFN-g and TNF-a expression at the gene level returned to normal at completion of treatment, while granzyme B levels remained undetectable at the cured stage. At the cured stage, the cellular activity monitors Ki67, CD69, GATA-3, CD8 and CD4 expressions were comparable to the healthy controls. Correlation analysis revealed a significantly strong negative relationship with CD244 expression, particularly between 1 T and 2 T (r = -0.94; p = 0.018), and 3 T (r = -0.95; p = 0.013). Comparing 0 T and 3 T, a genitive correlation existed in PD-L1 (r = -0.74) but statistically not significant, as seen in CTLA4 and LAG-3 expressions. CONCLUSION: Collectively, the findings of the study suggest that T-cells exhaustion marker particularly CD244, inflammatory markers IL-2, IFN-g and TNF-a, and cellular activity indicators such as Ki67, CD69, GATA-3, CD8 and CD4 are promising markers in monitoring the progress of PTB patients during treatment.

Metabolically active neutrophils represent a permissive niche for Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb)-infected neutrophils are often found in the airways of patients with active tuberculosis (TB), and excessive recruitment of neutrophils to the lung is linked to increased bacterial burden and aggravated pathology in TB. The basis for the permissiveness of neutrophils for Mtb and the ability to be pathogenic in TB has been elusive. Here, we identified metabolic and functional features of neutrophils that contribute to their permissiveness in Mtb infection. Using single-cell metabolic and transcriptional analyses, we found that neutrophils in the Mtb-infected lung displayed elevated mitochondrial metabolism, which was largely attributed to the induction of activated neutrophils with enhanced metabolic activities. The activated neutrophil subpopulation was also identified in the lung granulomas from Mtb-infected non-human primates. Functionally, activated neutrophils harbored more viable bacteria and displayed enhanced lipid uptake and accumulation. Surprisingly, we found that interferon-γ promoted the activation of lung neutrophils during Mtb infection. Lastly, perturbation of lipid uptake pathways selectively compromised Mtb survival in activated neutrophils. These findings suggest that neutrophil heterogeneity and metabolic diversity are key to their permissiveness for Mtb and that metabolic pathways in neutrophils represent potential host-directed therapeutics in TB.

Proteomics-based host-specific biomarkers for tuberculosis: The future of TB diagnosis.

Tuberculosis (TB) is an infectious disease that remains one of the major global public health concerns. Early detection of Active Pulmonary TB is therefore of utmost importance for controlling lethality and disease spreading. Currently available TB diagnostics can be broadly categorized into microscopy, culture-based, and molecular approaches, all of which come with compromised sensitivity, limited efficacy, and high expenses. Hence, rapid, sensitive, and affordable diagnostic methods for TB is the current prerequisite for disease management. This review summarizes the proteomics investigations for host-specific biomarkers from serum, sputum, saliva, and urine samples of TB patients, along with patients having comorbidity. Thorough data mining from available literature led us to conclude that the host-specific proteins involved in immunity and defense, metabolic regulation, cellular adhesion, and motility, inflammatory responses, and tissue remodelling have shown significant deregulation upon Mycobacterium tuberculosis (Mtb) infection. Notably, the immunoregulatory protein orosomucoid (ORM) was up-regulated in active TB compared to non-TB individuals, as observed in multiple studies from diverse sample types. Mannose receptor C type 2 (MRC2) was identified as an upregulated, treatment response biomarker in two independent serum proteomics investigations. Thorough mechanistic investigation on these candidate proteins would be fascinating to dig into potential drug targets and customized therapeutics for TB patients, along with their diagnostic potentials.

Host and pathogen factors that influence variability of Mycobacterium tuberculosis lipid body content in sputum from patients with tuberculosis: an observational study.

BACKGROUND: High proportions of Mycobacterium tuberculosis cells in sputum containing triacylglycerol-rich lipid bodies have been shown to be associated with treatment failure or relapse following antituberculous chemotherapy. Although lipid body determination is a potential biomarker for supporting clinical trial and treatment decisions, factors influencing variability in sputum frequencies of lipid body-positive (%LB+) M tuberculosis in patients are unknown. We aimed to test our hypothesis that exposure to host-generated NO and M tuberculosis strains are factors associated with differences in sputum %LB+. METHODS: In this observational study, we determined %LB+ frequencies before treatment by microscopy in patients with smear-positive tuberculosis from two separate prospective observational study settings (Gondar, Ethiopia, recruited between May 1, 2010, and April 30, 2011, and Fajara, The Gambia, who provided sputum samples before treatment between May 5, 2010, and Dec 22, 2011). In Ethiopia, fractional exhaled nitric oxide (FeNO) was measured as a biomarker of host NO, and M tuberculosis strain differences were determined by spoligotyping. Treatment response was assessed by percentage weight change after 7 months. In The Gambia, treatment responses were assessed as change in BMI and radiographic burden of disease after 6 months. Sputum M tuberculosis isolates were studied in vitro for their %LB+ and triacylglycerol synthase 1 (tgs1) mRNA responses to NO exposure. Propidium iodide staining was used as a measure of NO strain toxicity. Correlation between in vitro %LB+ frequencies following NO exposure and those of the same strain in sputum was examined with linear regression and Dunnett's multiple comparison test. FINDINGS: In Ethiopia, 73 patients who were smear positive for pulmonary tuberculosis were recruited (43 [59%] were male and 30 [41%] were female). Of these, the %LB+ in the sputum of 59 patients showed linear correlation with log10 FeNO (r2=0·28; p<0·0001) and an association with strain spoligotype was suggested. Seven M tuberculosis strains from The Gambia showed different dose-responses to NO in vitro, demonstrated by changing lipid body content, tgs1 transcription, and bacterial toxicity. In sputum %LB+ frequencies correlated with in vitro %LB+ responses to NO of the corresponding isolate. In a subset of 34 patients across both cohorts, higher sputum %LB+ frequencies before treatment were associated with weaker responses to treatment than lower sputum %LB+ frequencies. INTERPRETATION: M tuberculosis strain and exposure to host-generated NO are associated with sputum %LB+. Our results support the use of M tuberculosis strain-dependent sputum %LB+ as a predictive biomarker of treatment response. FUNDING: The Medical Research Council, the University of Leicester, and the University of Gondar.

Identification of a Diagnostic Multiomics-Based Biomarker Cluster in a Mouse Model of Pulmonary Tuberculosis.

BACKGROUND: Tuberculosis (TB) stands as the second most prevalent infectious agent-related cause of death worldwide in 2022, trailing only COVID-19. With 1.13 million reported deaths, this figure is more than half of the mortality associated with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), which accounted for 0.63 million deaths. Diagnosing Mycobacterium tuberculosis (MTB) infection remains a formidable challenge due to the inability to isolate and detect MTB in sputum and within the human body. The absence of universally reliable diagnostic criteria for MTB infection globally poses a significant obstacle to preventing the progression of tuberculosis from the MTB infection stage. METHODS: In this study, our objective was to formulate a diagnostic biomarker cluster capable of discerning the progression of MTB infection and disease. This was achieved through a comprehensive joint multiomics analysis, encompassing transcriptome, proteome, and metabolome, conducted on lung tissue samples obtained from both normal control mice and those infected with MTB. RESULTS: A total of 1690 differentially expressed genes and 94 differentially expressed proteins were systematically screened. From this pool, 10 core genes were singled out. Additionally, eight long non-coding ribonucleic acids and eight metabolites linked to these core genes were identified to establish a cohesive cluster of biomarkers. This multiomics-based biomarker cluster demonstrated its capability to differentiate uninfected samples from MTB-infected samples effectively in both principle component analysis and the construction of a random forest model. CONCLUSION: The outcomes of our study strongly suggest that the multiomics-based biomarker cluster holds significant potential for enhancing the diagnosis of MTB infection.

Mycobacterium tuberculosis resides in lysosome-poor monocyte-derived lung cells during chronic infection.

Mycobacterium tuberculosis (Mtb) infects lung myeloid cells, but the specific Mtb-permissive cells and host mechanisms supporting Mtb persistence during chronic infection are incompletely characterized. We report that after the development of T cell responses, CD11clo monocyte-derived cells harbor more live Mtb than alveolar macrophages (AM), neutrophils, and CD11chi monocyte-derived cells. Transcriptomic and functional studies revealed that the lysosome pathway is underexpressed in this highly permissive subset, characterized by less lysosome content, acidification, and proteolytic activity than AM, along with less nuclear TFEB, a regulator of lysosome biogenesis. Mtb infection does not drive lysosome deficiency in CD11clo monocyte-derived cells but promotes recruitment of monocytes that develop into permissive lung cells, mediated by the Mtb ESX-1 secretion system. The c-Abl tyrosine kinase inhibitor nilotinib activates TFEB and enhances lysosome functions of macrophages in vitro and in vivo, improving control of Mtb infection. Our results suggest that Mtb exploits lysosome-poor lung cells for persistence and targeting lysosome biogenesis is a potential host-directed therapy for tuberculosis.

Decreased mRNA expression of NR1H3 and ABCA1 in pulmonary tuberculosis patients from population of Punjab, India.

BACKGROUND: Mycobacterium tuberculosis (MTB) is the causative organism of tuberculosis. Cholesterol is a crucial carbon source required for the survival of MTB in host cells. Transcription factor NR1H3 along with its important target genes ABCA1 and ApoE play important role in removal of extra cholesterol from cells. Changes in the gene expression of NR1H3, ABCA1 and ApoE can affect cholesterol homeostasis and thus the survival of MTB in host cells.Therefore, the present study was designed to analyze the mRNA expression of NR1H3, ABCA1 and ApoE in pulmonary TB (PTB) patients from the population of Punjab, India. METHODS AND RESULTS: In this study, mRNA expression of the transcription factor NR1H3 and its target genes ABCA1 and ApoE was analyzed in 89 subjects, including 41 PTB patients and 48 healthy controls (HCs) by real-time quantitative PCR. It was found that the mRNA expression of both NR1H3 and ABCA1 genes was significantly lower in TB patients than in HCs (p < 0.001). Even after sex-wise stratification of the subjects, mRNA expression of NR1H3 and ABCA1 was found to be down-regulated in both male and female TB patients. No significant difference was observed in expression of ApoE (p = 0.98). CONCLUSIONS: The present study found that the mRNA expression of NR1H3 and ABCA1 is down-regulated in TB patients from Punjab state of India.

Inhibition of leukotriene-B4 signalling-mediated host response to tuberculosis is a potential mode of adjunctive host-directed therapy.

Treatment of tuberculosis (TB) is faced with several challenges including the long treatment duration, drug toxicity and tissue pathology. Host-directed therapy provides promising avenues to find compounds for adjunctively assisting antimycobacterials in the TB treatment regimen, by promoting pathogen eradication or limiting tissue destruction. Eicosanoids are a class of lipid molecules that are potent mediators of inflammation and have been implicated in aspects of the host response against TB. Here, we have explored the blood transcriptome of pulmonary TB patients to understand the activity of leukotriene B4, a pro-inflammatory eicosanoid. Our study shows a significant upregulation in the leukotriene B4 signalling pathway in active TB patients, which is reversed with TB treatment. We have further utilized our in-house network analysis algorithm, ResponseNet, to identify potential downstream signal effectors of leukotriene B4 in TB patients including STAT1/2 and NADPH oxidase at a systemic as well as local level, followed by experimental validation of the same. Finally, we show the potential of inhibiting leukotriene B4 signalling as a mode of adjunctive host-directed therapy against TB. This study provides a new mode of TB treatment along with mechanistic insights which can be further explored in pre-clinical trials.

Tuberculosis is associated with sputum metabolome variations, irrespective of patient sex or HIV status: an untargeted GCxGC-TOFMS study.

INTRODUCTION: Various studies have identified TB-induced metabolome variations. However, in most of these studies, a large degree of variation exists between individual patients. OBJECTIVES: To identify differential metabolites for TB, independent of patients' sex or HIV status. METHODS: Untargeted GCxGC/TOF-MS analyses were applied to the sputum of 31 TB + and 197 TB- individuals. Univariate statistics were used to identify metabolites which are significantly different between TB + and TB- individuals (a) irrespective of HIV status, and (b) with a HIV + status. Comparisons a and b were repeated for (i) all participants, (ii) males only and (iii) females only. RESULTS: Twenty-one compounds were significantly different between the TB + and TB- individuals within the female subgroup (11% lipids; 10% carbohydrates; 1% amino acids, 5% other and 73% unannotated), and 6 within the male subgroup (20% lipids; 40% carbohydrates; 6% amino acids, 7% other and 27% unannotated). For the HIV + patients (TB + vs. TB-), a total of 125 compounds were significant within the female subgroup (16% lipids; 8% carbohydrates; 12% amino acids, 6% organic acids, 8% other and 50% unannotated), and 44 within the male subgroup (17% lipids; 2% carbohydrates; 14% amino acids related, 8% organic acids, 9% other and 50% unannotated). Only one annotated compound, 1-oleoyl lysophosphaditic acid, was consistently identified as a differential metabolite for TB, irrespective of sex or HIV status. The potential clinical application of this compound should be evaluated further. CONCLUSIONS: Our findings highlight the importance of considering confounders in metabolomics studies in order to identify unambiguous disease biomarkers.

Proteomic analysis of peripheral blood mononuclear cells isolated from patients with pulmonary tuberculosis: A pilot study from Zanzibar, Tanzania.

This study aimed at exploring the proteomic profile of PBMCs to predict treatment response in pulmonary tuberculosis (PTB). This was a pilot study conducted among 8 adult patients from Zanzibar, Tanzania with confirmed PTB. Blood samples were collected at baseline, at 2 months of treatment, and at the end of treatment at 6 months. Proteins were extracted from PBMCs and analyzed using LC-MS/MS based label free quantitative proteomics. Overall, 3,530 proteins were quantified across the samples, and 12 differentially expressed proteins were identified at both 2 months of treatment and at treatment completion, which were involved in cellular and metabolic processes, as well as binding and catalytic activity. Seven were downregulated proteins (HSPA1B/HSPA1A, HSPH1, HSP90AA1, lipopolysaccharide-binding protein, complement component 9, calcyclin-binding protein, and protein transport protein Sec31A), and 5 proteins were upregulated (SEC14 domain and spectrin repeat-containing protein 1, leucine-rich repeat-containing 8 VRAC subunit D, homogentisate 1,2-dioxygenase, NEDD8-activating enzyme E1 regulatory subunit, and N-acetylserotonin O-methyltransferase-like protein). The results showed that proteome analysis of PBMCs can be used as a novel technique to identify protein abundance change with anti-tuberculosis treatment. The novel proteins elucidated in this work may provide new insights for understanding PTB pathogenesis, treatment, and prognosis.

Plasma Macrophage Migration Inhibitory Factor Concentration at Each Spectrum of Tuberculosis.

Macrophage migration inhibitory factor (MIF) is an inflammatory mediator in several diseases, including tuberculosis (TB). However, the role of MIF in each stage of TB remains to be further elucidated. Thus, this study aimed to analyze the differences in plasma MIF protein levels in patients with active pulmonary TB, positive and negative interferon-gamma release assay (IGRA) household contacts (HHCs), and healthy controls (HCs). Plasma MIF concentration was significantly higher in patients with active-new pulmonary tuberculosis (ATB) and HHCs compared with HCs (mean ± standard deviation: 17.32 ± 16.85, 16.29 ± 14.21, and 7.29 ± 5.39 ng/mL, respectively; P = 0.002). The plasma MIF concentration was not statistically different when compared between patients with ATB, IGRA-positive HHCs (17.44 ± 16.6 ng/mL), and IGRA-negative HHCs (14.34 ± 8.7 ng/mL) (P = 0.897). In conclusion, ATB patients, IGRA-positive HHCs, and IGRA-negative HHCs have a higher MIF concentration than HCs. This shows the involvement of MIF in each stage of TB, starting from TB exposure and infection, but not symptomatic, to the active stage.

SIRPα maintains macrophage homeostasis by interacting with PTK2B kinase in Mycobacterium tuberculosis infection and through autophagy and necroptosis.

BACKGROUND: To determine whether SIRPα can be a diagnostic marker of pulmonary tuberculosis (PTB) and the molecular mechanism of SIRPα regulating macrophages to kill Mycobacterium tuberculosis (MTB). METHODS: Meta-analysis combined with subsequent qRT-PCR, western-blotting and flow cytometry assay were used to detect SIRPα expression in PTB patients. Cell-based assays were used to explore the regulation of macrophage function by SIRPα. SIRPα-/- and wide type macrophages transplanted C57BL/6J mice were used to determine the function of SIRPα on MTB infection in vivo. FINDINGS: SIRPα levels are closely correlated with the treatment outcomes among PTB patients. Cell-based assay demonstrated that MTB significantly induces the expression of SIRPα on macrophages. SIRPα deficiency enhances the killing ability of macrophages against MTB through processes that involve enhanced autophagy and reduced necroptosis of macrophages. Mechanistically, SIRPα forms a direct interaction with PTK2B through its intracellular C-terminal domain, thus inhibiting PTK2B activation in macrophages. Necroptosis inhibition due to SIRPα deficiency requires PTK2B activity. The transfer of SIRPα-deficient bone marrow-derived macrophages (BMDMs) into wild type mice resulted in a drop of bacterial load in the lungs but an enhancement of inflammatory lung damage, and the combination of ulinastatin and SIRPα-/-→WT treatment could decrease the inflammation and maintain the bactericidal capacity. INTERPRETATION: Our data define SIRPα a novel biomarker for tuberculosis infection and underlying mechanisms for maintaining macrophage homeostasis. FUNDING: This work was financially supported by the Chinese National Natural Science Foundation project (No.81401635). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

[Action Mechanism of Ethambutol Tablets on Pulmonary Tuberculosis Rat Model Based on Janus Kinase/Signal Transducer and Activator of Transcription Signaling Pathway].

Objective To explore the therapeutic effect of ethambutol tablets (EMB) on pulmonary tuberculosis (PTB) in rats and whether the action mechanism of EMB is related to Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway. Methods Sixty SD rats were assigned into a control group,a PTB group,a PTB+EMB group (30 mg/kg),and a PTB+EMB+Colivelin (JAK/STAT pathway activator) group (30 mg/kg+1 mg/kg) via the random number table method,with 15 rats in each group.The rats in other groups except the control group were injected with 0.2 ml of 5 mg/ml Mycobacterium tuberculosis suspension to establish the PTB model.After the modeling,the rats were administrated with corresponding drugs for 4 consecutive weeks (once a day).On days 1,14,and 28 of administration,the body weights of rats were measured and the Mycobacterium tuberculosis colonies were counted.Hematoxylin-eosin staining was carried out to detect the pathological changes in the lung tissue.Enzyme-linked immunosorbent assay was employed to measure the levels of interleukin(IL)-6,tumor necrosis factor-α (TNF-α),IL-1ß,and interferon-γ (IFN-γ) in the serum.Flow cytometry was used to determine the levels of T lymphocyte subsets CD3+,CD4+,CD8+,and CD4+/CD8+.The 16S rRNA sequencing was performed to detect the relative abundance of the intestinal microorganisms.Western blotting was employed to determine the expression of the proteins in the JAK/STAT pathway. Results Compared with the control group,the modeling of PTB reduced the rat body weight (on days 14 and 28),increased Mycobacterium tuberculosis colonies,caused severe pathological changes in the lung tissue,and elevated the levels of IL-6,TNF-α,and IL-1ß in serum and CD8+.Moreover,the modeling increased the relative abundance of Bacteroides,Peptococcus,Clostridium,Actinomyces,Lactobacillus,Verrucomicrobium,and Veillonella in the intestine,up-regulated the protein levels of phosphorylated JAK2 and phosphorylated STAT3 in the lung tissue,and lowered the levels of CD3+,CD4+,CD4+/CD8+,and IFN-γ levels (all P<0.001).Compared with the PTB group,PTB+EMB increased the rat body weight (on days 14 and 28),reduced Mycobacterium tuberculosis colonies,alleviated the pathological damage in lung tissue,lowered the levels of IL-6,TNF-α,and IL-1ß in serum and CD8+.Moreover,the treatment decreased the relative abundance of Bacteroides,Peptococcus,Clostridium,Actinomyces,Lactobacillus,Verrucomicrobium,Veillonella in the intestine,down-regulated the protein levels of phosphorylated JAK2 and phosphorylated STAT3 in the lung tissue,and elevated the levels of CD3+,CD4+,CD4+/CD8+,and IFN-γ (all P<0.001).Colivelin weakened the alleviation effect of EMB on PTB (all P<0.001). Conclusion EMB can inhibit the JAK/STAT signaling pathway to alleviate the PTB in rat.

Persistent expression of activation markers on Mycobacterium tuberculosis-specific CD4 T cells in smear negative TB patients.

BACKGROUND: T cell activation (HLA-DR, CD-38), proliferation (KI-67), and functional (IFN-γ, TNF-α) markers have recently been shown to be useful in predicting and monitoring anti-TB responses in smear positive TB, but previous research did not characterize the activation and proliferation profiles after therapy of smear negative TB. METHODOLOGY: In this study, we used polychromatic flow cytometry to assess selected PPD-specific T cell markers using fresh PBMC of smear negative and positive pulmonary tuberculosis (PTB) patients, recruited from health facilities in Addis Ababa. RESULT: Levels of activation (HLA-DR, CD38) and proliferation (Ki-67) among total unstimulated CD4 T cells decreased significantly after therapy, particularly at month 6. Similarly, levels of PPD-specific T cell activation markers (HLA-DR, CD-38) were significantly lower in smear positive PTB patients following treatment, whereas a consistent decline in these markers was less apparent among smear negative PTB patients at the sixth month. CONCLUSION: After six months of standard anti-TB therapy, persistent levels of activation of HLA-DR and CD-38 from PPD specific CD4+T cells in this study could indicate that those markers have little value in monitoring and predicting anti-TB treatment response in smear negative pulmonary TB patients in Ethiopian context.

Differential expression of genes regulated by the glucocorticoid receptor pathway in patients with pulmonary tuberculosis.

AIMS: Previous studies in TB patients showed an immuno-endocrine imbalance characterized by a disease-severity associated increase in plasma levels of proinflammatory cytokines and glucocorticoids (GCs). To analyze the potential immunomodulatory effect of circulating GCs over peripheral blood mononuclear cells (PBMC) from TB patients, we investigated the expression of positively (anti-inflammatory-related genes ANXA1; FKBP51; GILZ, NFKBIA, and NFKBIB) and negatively (inflammatory genes: IL-6, IL-1ß, and IFN-γ) Glucocorticoids Receptors (GR)-regulated genes. Plasma concentrations of cytokines and hormones, together with specific lymphoproliferation were also assessed. MATERIALS AND METHODS: Gene expression was quantified by RT-qPCR, specific lymphoproliferation by 3H-thymidine incorporation, whereas plasma cytokines and hormones levels by ELISA. KEY FINDINGS: Transcripts of ANXA1, GILZ, NFKBIB, and NFKBIA appeared significantly increased in patients, whereas FKBP51, IL-6, IL-1ß, and NF-κB remained unchanged. Upon analyzing according to disease severity, mRNA levels for ANXA1 and NFKBIB were even higher in moderate and severe patients. GILZ was increased in moderate cases, with NFKBIA and IL-1 ß being higher in severe ones, who also displayed increased GRß transcripts. TB patients had reduced plasma DHEA concentrations together with increased pro and anti-inflammatory cytokines (IFN-γ, IL-6, and IL-10) cortisol and cortisol/DHEA ratio, more evident in progressive cases, in whom their PBMC also showed a decreased mycobacterial-driven proliferation. The cortisol/DHEA ratio and GRα expression were positively correlated with GR-regulated genes mainly in moderate patients. SIGNIFICANCE: The increased expression of cortisol-regulated anti-inflammatory genes in TB patients-PBMC, predominantly in progressive disease, seems compatible with a relatively insufficient attempt to downregulate the accompanying inflammation.

PD-L1 Expression in Monocytes Correlates with Bacterial Burden and Treatment Outcomes in Active Pulmonary Tuberculosis.

The PD-1/PD-L1 pathway is critical in T cell biology; however, the role of the PD-1/PD-L1 pathway in clinical characteristics and treatment outcomes in pulmonary tuberculosis (PTB) patients is unclear. We prospectively enrolled PTB, latent TB infection (LTBI), and non-TB, non-LTBI subjects. The expression of PD-1/PD-L1 on peripheral blood mononuclear cells (PBMCs) was measured and correlated with clinical characteristics and treatment outcomes in PTB patients. Immunohistochemistry and immunofluorescence were used to visualize PD-1/PD-L1-expressing cells in lung tissues from PTB patients and from murine with heat-killed MTB (HK-MTB) treatment. A total of 76 PTB, 40 LTBI, and 28 non-TB, non-LTBI subjects were enrolled. The expression of PD-1 on CD4+ T cells and PD-L1 on CD14+ monocytes was significantly higher in PTB cases than non-TB subjects. PTB patients with sputum smear/culture unconversion displayed higher PD-L1 expression on monocytes. PD-L1-expressing macrophages were identified in lung tissue from PTB patients, and co-localized with macrophages in murine lung tissues. Mycobacterium tuberculosis (MTB) whole cell lysate/EsxA stimulation of human and mouse macrophages demonstrated increased PD-L1 expression. In conclusion, increased expression of PD-L1 on monocytes in PTB patients correlated with higher bacterial burden and worse treatment outcomes. The findings suggest the involvement of the PD-1/PD-L1 pathway in MTB-related immune responses.