Serum cytokine biosignatures for identification of tuberculosis among HIV-positive inpatients.

BACKGROUND: Serum cytokines correlate with tuberculosis (TB) progression and are predictors of TB recurrence in people living with HIV. We investigated whether serum cytokine biosignatures could diagnose TB among HIV-positive inpatients. METHODS: We recruited HIV-positive inpatients with symptoms of TB and measured serum levels of inflammation biomarkers including IL-2, IL-4, IL-6, IL-10, tumour necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ). We then built and tested our TB prediction model. RESULTS: 236 HIV-positive inpatients were enrolled in the first cohort and all the inflammation biomarkers were significantly higher in participants with microbiologically confirmed TB than those without TB. A binary support vector machine (SVM) model was built, incorporating the data of four biomarkers (IL-6, IL-10, TNF-α and IFN-γ). Efficacy of the SVM model was assessed in training (n=189) and validation (n=47) sets with area under the curve (AUC) of 0.92 (95% CI 0.88 to 0.96) and 0.85 (95% CI 0.72 to 0.97), respectively. In an independent test set (n=110), the SVM model yielded an AUC of 0.85 (95% CI 0.76 to 0.94) with 78% (95% CI 68% to 87%) specificity and 85% (95% CI 66% to 96%) sensitivity. Moreover, the SVM model outperformed interferon-gamma release assay (IGRA) among advanced HIV-positive inpatients irrespective of CD4+ T-cell counts, which may be an alternative approach for identifying Mycobacterium tuberculosis infection among HIV-positive inpatients with negative IGRA. CONCLUSIONS: The four-cytokine biosignature model successfully identified TB among HIV-positive inpatients. This diagnostic model may be an alternative approach to diagnose TB in advanced HIV-positive inpatients with low CD4+ T-cell counts.

Mitochondrial Fusion Mediated by Mitofusin 1 Regulates Macrophage Mycobactericidal Activity by Enhancing Autophagy.

A mitochondrion, as a highly dynamic organelle, continuously changes morphology and position during its life cycle. Mitochondrial dynamics, including fission and fusion, play a critical role in maintaining functional mitochondria for ATP production, which is directly linked to host defense against Mycobacterium tuberculosis infection. However, how macrophages regulate mitochondrial dynamics during M. tuberculosis infection remains elusive. In this study, we found that M. tuberculosis infection induced mitochondrial fusion by enhancing the expression of mitofusin 1 (MFN1), which resulted in increased ATP production. Silencing of MFN1 inhibited mitochondrial fusion and subsequently reduced ATP production, which, in turn, severely impaired macrophages' mycobactericidal activity by inhibiting autophagy. Impairment of mycobactericidal activity and autophagy was replicated using oligomycin, an inhibitor of ATP synthase. In summary, our study revealed that MFN1-mediated mitochondrial fusion is essential for macrophages' mycobactericidal activity through the regulation of ATP-dependent autophagy. The MFN1-mediated metabolism pathway might be a target for the development of a host direct therapy (HDT) strategy against tuberculosis.

Evaluations of the serological test in the diagnosis of 2019 novel coronavirus (SARS-CoV-2) infections during the COVID-19 outbreak.

We developed a chemiluminescence immunoassay method based on the recombinant nucleocapsid antigen and assessed its performance for the clinical diagnosis of severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infections by detecting SARS-CoV-2-specific IgM and IgG antibodies in patients. Full-length recombinant nucleocapsid antigen and tosyl magnetic beads were used to develop the chemiluminescence immunoassay approach. Plasmas from 29 healthy cohorts, 51 tuberculosis patients, and 79 confirmed SARS-CoV-2 patients were employed to evaluate the chemiluminescence immunoassay method performance for the clinical diagnosis of SARS-CoV-2 infections. A commercial ELISA kit (Darui Biotech, China) using the same nucleocapsid antigen was used for the in-parallel comparison with our chemiluminescence immunoassay method. The IgM and IgG manner of testing in the chemiluminescence immunoassay method showed a sensitivity and specificity of 60.76% (95% CI 49.1 to 71.6) and 92.25% (95% CI 83.4 to 97.2) and 82.28% (95% CI 72.1 to 90.0) and 97.5% (95% CI 91.3 to 99.7), respectively. Higher sensitivity and specificity were observed in the chemiluminescence immunoassay method compared with the Darui Biotech ELISA kit. The developed high sensitivity and specificity chemiluminescence immunoassay IgG testing method combined with the RT-PCR approach can improve the clinical diagnosis for SARS-CoV-2 infections and thus contribute to the control of COVID-19 expansion.

Biomarkers of iron metabolism facilitate clinical diagnosis in Mycobacterium tuberculosis infection.

BACKGROUND: Perturbed iron homeostasis is a risk factor for tuberculosis (TB) progression and an indicator of TB treatment failure and mortality. Few studies have evaluated iron homeostasis as a TB diagnostic biomarker. METHODS: We recruited participants with TB, latent TB infection (LTBI), cured TB (RxTB), pneumonia (PN) and healthy controls (HCs). We measured serum levels of three iron biomarkers including serum iron, ferritin and transferrin, then established and validated our prediction model. RESULTS: We observed and verified that the three iron biomarker levels correlated with patient status (TB, HC, LTBI, RxTB or PN) and with the degree of lung damage and bacillary load in patients with TB. We then built a TB prediction model, neural network (NNET), incorporating the data of the three iron biomarkers. The model showed good performance for diagnosis of TB, with 83% (95% CI 77 to 87) sensitivity and 86% (95% CI 83 to 89) specificity in the training data set (n=663) and 70% (95% CI 58 to 79) sensitivity and 92% (95% CI 86 to 96) specificity in the test data set (n=220). The area under the curves (AUCs) of the NNET model to discriminate TB from HC, LTBI, RxTB and PN were all >0.83. Independent validation of the NNET model in a separate cohort (n=967) produced an AUC of 0.88 (95% CI 0.85 to 0.91) with 74% (95% CI 71 to 77) sensitivity and 92% (95% CI 87 to 96) specificity. CONCLUSIONS: The established NNET TB prediction model discriminated TB from HC, LTBI, RxTB and PN in a large cohort of patients. This diagnostic assay may augment current TB diagnostics.

BTLA-expressing CD11c antigen presenting cells in patients with active tuberculosis exhibit low capacity to stimulate T cell proliferation.

Despite past extensive studies on B and T lymphocyte attenuator (BTLA)-mediated negative regulation of T cell activation, the role of BTLA in antigen presenting cells (APCs) in patients with active pulmonary tuberculosis (ATB) remains poorly understood. Here, we demonstrate that BTLA expression on CD11c APCs increased in patients with ATB. Particularly, BTLA expression in CD11c APCs was likely associated with the attenuated stimulatory capacity on T cells (especially CD8+ T cell) proliferation. BTLA-expressing CD11c APCs showed lower antigen uptake capacity, lower CD86 expression, higher HLA-DR expression, and enhanced IL-6 secretion, compared to counterpart BTLA negative CD11c APCs in healthy controls (HC). Interestingly, BTLA-expressing CD11c APCs from ATB patients displayed lower expression of HLA-DR and less IL-6 secretion, but higher expression of CD86 than those from HC volunteers. Mixed lymphocyte reaction suggests that BTLA expression is likely associated with positive rather than conventional negative regulation of CD11c APCs stimulatory capacity. This role is impaired in ATB patients manifested by low expression of HLA-DR and low production of IL-6. This previous unappreciated role for BTLA may have implications in the prevention and treatment of patients with ATB.

IL-6 Inhibition Reduces STAT3 Activation and Enhances the Antitumor Effect of Carboplatin.

Recent studies suggest that tumor-associated macrophage-produced IL-6 is an important mediator within the tumor microenvironment that promotes tumor growth. The activation of IL-6/STAT3 axis has been associated with chemoresistance and poor prognosis of a variety of cancers including colorectal carcinoma and thus serves as a potential immunotherapeutic target for cancer treatment. However, it is not fully understood whether anticytokine therapy could reverse chemosensitivity and enhance the suppressive effect of chemotherapy on tumor growth. In this study, we aimed to investigate the effect of IL-6 inhibition therapy on the antitumor effect of carboplatin. Enhanced expression of IL-6 and activation of STAT3 were observed in human colorectal carcinoma samples compared to normal colorectal tissue, with higher levels of IL-6/STAT3 in low grade carcinomas. Treatment of carboplatin (CBP) dose-dependently increased IL-6 production and STAT3 activation in human colorectal LoVo cells. Blockade of IL-6 with neutralizing antibody enhanced chemosensitivity of LoVo cells to carboplatin as evidenced by increased cell apoptosis. IL-6 blockade abolished carboplatin-induced STAT3 activation. IL-6 blockade and carboplatin synergistically reduced cyclin D1 expression and enhanced caspase-3 activity in LoVo cells. Our results suggest that inhibition of IL-6 may enhance chemosensitivity of colon cancers with overactive STAT3 to platinum agents.

Mycobacterium tuberculosis induces host autophagic ferritin degradation for enhanced iron bioavailability and bacterial growth.

ABBREVIATIONS: Mtb, Mycobacterium tuberculosis; TB, tuberculosis; NCOA4, nuclear receptor coactivator 4; p38, p38 protein kinase; AKT1, AKT serine/threonine kinase 1; TRIM21, tripartite motif containing 21; FTH1, ferritin heavy chain 1; FTL, ferritin light chain; HERC2, HECT and RLD domain containing E3 ubiquitin protein ligase 2.

Oregano essential oil modulates colonic homeostasis and intestinal barrier function in fattening bulls.

Oregano essential oil (OEO) primarily contains phenolic compounds and can serve as a dietary supplement for fattening bulls. However, the precise molecular mechanism underlying this phenomenon remains largely elusive. Therefore, this study investigated the impact of adding OEO to diet on the integrity of the intestinal barrier, composition of the colonic microbiome, and production of microbial metabolites in fattening bulls. Our goal was to provide insights into the utilization of plant essential oil products in promoting gastrointestinal health and welfare in animals. We employed amplicon sequencing and metabolome sequencing techniques to investigate how dietary supplementation with OEO impacted the intestinal barrier function in bulls. The inclusion of OEO in the diet resulted in several notable effects on the colon of fattening bulls. These effects included an increase in the muscle thickness of the colon, goblet cell number, short-chain fatty acid concentrations, digestive enzyme activity, relative mRNA expression of intestinal barrier-related genes, and relative expression of the anti-inflammatory factor IL-10. Additionally, α-amylase activity and the relative mRNA expression of proinflammatory cytokines decreased. Moreover, dietary OEO supplementation increased the abundance of intestinal Bacteroides, Coprobacillus, Lachnospiraceae_UCG_001, and Faecalitalea. Metabolomic analysis indicated that OEO primarily increased the levels of 5-aminovaleric acid, 3-methoxysalicylic acid, and creatinine. In contrast, the levels of maltose, lactulose, lactose, and D-trehalose decreased. Correlation analysis showed that altered colonic microbes and metabolites affected intestinal barrier function. Taken together, these results demonstrate that OEO facilitates internal intestinal environmental homeostasis by promoting the growth of beneficial bacteria while inhibiting harmful ones.

Mycobacterium tuberculosis hijacks host TRIM21- and NCOA4-dependent ferritinophagy to enhance intracellular growth.

Ferritin, a key regulator of iron homeostasis in macrophages, has been reported to confer host defenses against Mycobacterium tuberculosis (Mtb) infection. Nuclear receptor coactivator 4 (NCOA4) was recently identified as a cargo receptor in ferritin degradation. Here, we show that Mtb infection enhanced NCOA4-mediated ferritin degradation in macrophages, which in turn increased the bioavailability of iron to intracellular Mtb and therefore promoted bacterial growth. Of clinical relevance, the upregulation of FTH1 in macrophages was associated with tuberculosis (TB) disease progression in humans. Mechanistically, Mtb infection enhanced NCOA4-mediated ferritin degradation through p38/AKT1- and TRIM21-mediated proteasomal degradation of HERC2, an E3 ligase of NCOA4. Finally, we confirmed that NCOA4 deficiency in myeloid cells expedites the clearance of Mtb infection in a murine model. Together, our findings revealed a strategy by which Mtb hijacks host ferritin metabolism for its own intracellular survival. Therefore, this represents a potential target for host-directed therapy against tuberculosis.

Mycobacterium tuberculosis-Induced Upregulation of the COX-2/mPGES-1 Pathway in Human Macrophages Is Abrogated by Sulfasalazine.

Macrophages are the primary human host cells of intracellular Mycobacterium tuberculosis (M.tb) infection, where the magnitude of inflammatory reactions is crucial for determining the outcome of infection. Previously, we showed that the anti-inflammatory drug sulfasalazine (SASP) significantly reduced the M.tb bactericidal burden and histopathological inflammation in mice. Here, we asked which genes in human inflammatory macrophages are affected upon infection with M.tb and how would potential changes impact the functional state of macrophages. We used a flow cytometry sorting system which can distinguish the dead and alive states of M.tb harbored in human monocyte-derived macrophages (MDM). We found that the expression of cyclooxygenase-2 and microsomal prostaglandin E2 synthase (mPGES)-1 increased significantly in tagRFP+ MDM which were infected with alive M.tb. After exposure of polarized M1-MDM to M.tb (H37Rv strain)-conditioned medium (MTB-CM) or to the M.tb-derived 19-kD antigen, the production of PGE2 and pro-inflammatory cytokines increased 3- to 4-fold. Upon treatment of M1-MDM with SASP, the MTB-CM-induced expression of COX-2 and the release of COX products and cytokines decreased. Elevation of PGE2 in M1-MDM upon MTB-CM stimulation and modulation by SASP correlated with the activation of the NF-κB pathway. Together, infection of human macrophages by M.tb strongly induces COX-2 and mPGES-1 expression along with massive PGE2 formation which is abrogated by the anti-inflammatory drug SASP.

Single-cell immune profiling reveals functional diversity of T cells in tuberculous pleural effusion.

Orchestration of an effective T lymphocyte response at infection sites is critical for protection against Mycobacterium tuberculosis (Mtb) infection. However, the local T cell immunity landscape in human tuberculosis is poorly defined. Tuberculous pleural effusion (TPE), caused by Mtb, is characterized by an influx of leukocytes to the pleural space, providing a platform suitable for delineating complex tissue responses to Mtb infection. Using single-cell transcriptomics and T cell receptor sequencing, we analyzed mononuclear cell populations in paired pleural fluid and peripheral blood of TPE patients. While all major cell clusters were present in both tissues, their relative proportions varied significantly by anatomic location. Lineage tracking analysis revealed subsets of CD8 and CD4 T cell populations with distinct effector functions specifically expanded at pleural sites. Granzyme K-expressing CD8 T cells were preferentially enriched and clonally expanded in pleural fluid from TPE, suggesting that they are involved in the pathogenesis of the disease. The findings collectively reveal the landscape of local T cell immunity in tuberculosis.

Mycobacterium tuberculosis Utilizes Host Histamine Receptor H1 to Modulate Reactive Oxygen Species Production and Phagosome Maturation via the p38MAPK-NOX2 Axis.

Tuberculosis (TB), which is caused by the single pathogenic bacterium, Mycobacterium tuberculosis, is among the top 10 lethal diseases worldwide. This situation has been exacerbated by the increasing number of cases of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). Histamine is an organic nitrogenous compound that mediates a plethora of cell processes via different receptors. The expression of histamine receptor H1 (HRH1), one of the four histamine receptors identified to date was previously reported to be augmented by M. tuberculosis infection, although the underlying mechanism is unclear. In the present study, we applied confocal microscopy, flow cytometry, and Western blotting to show that HRH1 expression was enhanced in macrophages following mycobacterial infection. Furthermore, by combining techniques of gene knockdown, immunoprecipitation, intracellular bacterial burden analysis, fluorescence labeling, and imaging, we found that M. tuberculosis targeted the host HRH1 to suppress NOX2-mediated cROS production and inhibit phagosome maturation and acidification via the GRK2-p38MAPK signaling pathway. Our findings clarified the underlying mechanism of the M. tuberculosis and host HRH1 interaction and may provide useful information for the development of novel antituberculosis treatments. IMPORTANCE Once engulfed in macrophage phagosomes, M. tuberculosis adopts various strategies to take advantage of the host environment for its intracellular survival. Histamine is an organic nitrogen-containing compound that mediates a plethora of cellular processes via different receptors, but the crosstalk mechanism between M. tuberculosis and HRH1 in macrophages is not clear. Our results revealed that M. tuberculosis infection enhanced HRH1 expression, which in turn restrained macrophage bactericidal activity by modulating the GRK2-p38MAPK signaling pathway, inhibiting NOX2-mediated cROS production and phagosome maturation. Clarification of the underlying mechanism by which M. tuberculosis utilizes host HRH1 to favor its intracellular survival may provide useful information for the development of novel antituberculosis treatments.

Autoantibody-Mediated Erythrophagocytosis Increases Tuberculosis Susceptibility in HIV Patients.

Macrophage dysfunction is associated with increased tuberculosis (TB) susceptibility in patients with human immunodeficiency virus (HIV) infection. However, the mechanisms underlying how HIV infection impairs macrophage function are unclear. Here, we found that levels of autoantibodies against red blood cells (RBCs) were significantly elevated in patients with HIV as determined by direct antiglobulin test (DAT). DAT positivity was significantly associated with TB incidence in both univariate and multivariate analyses (odds ratio [OR] = 11.96 [confidence interval {CI}, 4.68 to 30.93] and 12.65 [3.33 to 52.75], respectively). Ex vivo analysis showed that autoantibodies against RBCs enhanced erythrophagocytosis and thus significantly impaired macrophage bactericidal function against intracellular Mycobacterium tuberculosis Mechanistically, autoantibody-mediated erythrophagocytosis increased heme oxygenase-1 (HO-1) expression, which inhibited M. tuberculosis-induced autophagy in macrophages. Silencing ATG5, a key component for autophagy, completely abrogated the effect of erythrophagocytosis on macrophage bactericidal activity against M. tuberculosis In conclusion, we have demonstrated that HIV infection increases autoantibody-mediated erythrophagocytosis. This process impairs macrophage bactericidal activity against M. tuberculosis by inhibiting HO-1-associated autophagy. These findings reveal a novel mechanism as to how HIV infection increases TB susceptibility.IMPORTANCE HIV infection significantly increases TB susceptibility due to CD4 T-cell loss and macrophage dysfunction. Although it is relatively clear that CD4 T-cell loss represents a direct effect of HIV infection, the mechanism underlying how HIV infection dampens macrophage function is unknown. Here, we show that HIV infection enhances autoantibody-mediated erythrophagocytosis, which dampens macrophage bactericidal activity against TB by inhibiting HO-1-associated autophagy. Our findings reveal a novel mechanism explaining how HIV infection increases susceptibility to TB. We propose that DAT could be a potential measure to identify HIV patients who are at high TB risk and who would be suitable for anti-TB chemotherapy preventive treatment.

Elevation in the counts of IL-35-producing B cells infiltrating into lung tissue in mycobacterial infection is associated with the downregulation of Th1/Th17 and upregulation of Foxp3+Treg.

IL-35 is an anti-inflammatory cytokine and is thought to be produced by regulatory T (Treg) cells. A previous study found that IL-35 was upregulated in the serum of patients with active tuberculosis (ATB), and IL-35-producing B cells infiltrated to tuberculous granuloma of patients with ATB. Purified B cells from such patients generated more IL-35 after stimulation by antigens of Mycobacterium tuberculosis and secreted more IL-10. However, the function and the underlying mechanisms of IL-35-producing B cells in TB progression have not been investigated. The present study found that the expression of mRNA of IL-35 subsets Ebi3 and p35 was elevated in mononuclear cells from peripheral blood, spleen, bone marrow, and lung tissue in a mouse model infected with Mycobacterium bovis BCG, as tested by real-time polymerase chain reaction. Accordingly, the flow cytometry analysis showed that the counts of a subset of IL-35+ B cells were elevated in the circulating blood and in the spleen, bone marrow, and lung tissue in BCG-infected mice, whereas anti-TB therapy reduced IL-35-producing B cells. Interestingly, BCG infection could drive the infiltration of IL-35-producing B cells into the lung tissue, and the elevated counts of IL-35-producing B cells positively correlated with the bacterial load in the lungs. Importantly, the injection of exogenous IL-35 stimulated the elevation in the counts of IL-35-producing B cells and was associated with the downregulation of Th1/Th17 and upregulation of Foxp3+Treg.The study showed that a subset of IL-35-producing B cells might take part in the downregulation of immune response in mycobacterial infection.

Single-cell transcriptomics of blood reveals a natural killer cell subset depletion in tuberculosis.

BACKGROUND: Tuberculosis (TB) continues to be a critical global health problem, which killed millions of lives each year. Certain circulating cell subsets are thought to differentially modulate the host immune response towards Mycobacterium tuberculosis (Mtb) infection, but the nature and function of these subsets is unclear. METHODS: Peripheral blood mononuclear cells (PBMC) were isolated from healthy controls (HC), latent tuberculosis infection (LTBI) and active tuberculosis (TB) and then subjected to single-cell RNA sequencing (scRNA-seq) using 10 × Genomics platform. Unsupervised clustering of the cells based on the gene expression profiles using the Seurat package and passed to tSNE for clustering visualization. Flow cytometry was used to validate the subsets identified by scRNA-Seq. FINDINGS: Cluster analysis based on differential gene expression revealed both known and novel markers for all main PBMC cell types and delineated 29 cell subsets. By comparing the scRNA-seq datasets from HC, LTBI and TB, we found that infection changes the frequency of immune-cell subsets in TB. Specifically, we observed gradual depletion of a natural killer (NK) cell subset (CD3-CD7+GZMB+) from HC, to LTBI and TB. We further verified that the depletion of CD3-CD7+GZMB+ subset in TB and found an increase in this subset frequency after anti-TB treatment. Finally, we confirmed that changes in this subset frequency can distinguish patients with TB from LTBI and HC. INTERPRETATION: We propose that the frequency of CD3-CD7+GZMB+ in peripheral blood could be used as a novel biomarker for distinguishing TB from LTBI and HC. FUND: The study was supported by Natural Science Foundation of China (81770013, 81525016, 81772145, 81871255 and 91942315), National Science and Technology Major Project (2017ZX10201301), Science and Technology Project of Shenzhen (JCYJ20170412101048337) and Guangdong Provincial Key Laboratory of Regional Immunity and Diseases (2019B030301009). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Interleukin-22 receptor 1 is expressed in multinucleated giant cells: A study on intestinal tuberculosis and Crohn's disease.

BACKGROUND: It is challenging to distinguish intestinal tuberculosis from Crohn's disease due to dynamic changes in epidemiology and similar clinical characteristics. Recent studies have shown that polymorphisms in genes involved in the interleukin (IL)-23/IL-17 axis may affect intestinal mucosal immunity by affecting the differentiation of Th17 cells. AIM: To investigate the specific single-nucleotide polymorphisms (SNPs) in genes involved in the IL-23/IL-17 axis and possible pathways that affect susceptibility to intestinal tuberculosis and Crohn's disease. METHODS: We analysed 133 patients with intestinal tuberculosis, 128 with Crohn's disease, and 500 normal controls. DNA was extracted from paraffin-embedded specimens or whole blood. Four SNPs in the IL23/Th17 axis (IL22 rs2227473, IL1ß rs1143627, TGFß rs4803455, and IL17 rs8193036) were genotyped with TaqMan assays. The transcriptional activity levels of different genotypes of rs2227473 were detected by dual luciferase reporter gene assay. The expression of IL-22R1 in different intestinal diseases was detected by immunohistochemistry. RESULTS: The A allele frequency of rs2227473 (P = 0.030, odds ratio = 0.60, 95% confidence interval: 0.37-0.95) showed an abnormal distribution between intestinal tuberculosis and healthy controls. The presence of the A allele was associated with a higher IL-22 transcriptional activity (P < 0.05). In addition, IL-22R1 was expressed in intestinal lymphoid tissues, especially under conditions of intestinal tuberculosis, and highly expressed in macrophage-derived Langhans giant cells. The results of immunohistochemistry showed that the expression of IL-22R1 in patients with Crohn's disease and intestinal tuberculosis was significantly higher than that in patients with intestinal polyps and colon cancer (P < 0.01). CONCLUSION: High IL-22 expression seems to be a protective factor for intestinal tuberculosis. IL-22R1 is expressed in Langhans giant cells, suggesting that the IL-22/IL-22R1 system links adaptive and innate immunity.

MTB driven B cells producing IL-35 and secreting high level of IL-10 in the patients with active pulmonary tuberculosis.

Regulatory B cells (Bregs) have critical roles as a negative regulator of immunity, mainly due to the fact that it secrets high a level of interleukin 10 (IL-10). Recently, a new subset of Bregs was identified as a key source of IL-35, which is an immunosuppressive cytokine and conventionally thought to be secreted by regulatory T cells (Tregs). Our previous study showed that the level of IL-35 in serum was elevated in the patients with active tuberculosis (ATB). However, none of the studies reported that IL-35 is secreted by B cells in ATB patients. In the current study, we found that the mRNA expressions of the both subunits (p35 and Ebi3) of IL-35 by circulating B cells were increased in ATB patients. By using immunohistochemistry and immunofluorescence staining, we found a subset of B cells infiltrated into the tuberculous granuloma of ATB patients also expressed IL-35. Moreover, Mycobacterium tuberculosis (MTB) lysate stimulation assay also demonstrated higher levels of IL-35 were exerted by MTB lysate within purified B cells from healthy control group (HC). Flow cytometry analysis further showed that the IL-35-producing B cells from ATB patients produced a higher level of IL-10. Taken together, IL-35-producing B cells may play a regulatory role during MTB infection by producing IL-10.

Empirical treatment with non-anti-tuberculosis antibiotics decreased microbiological detection in cervical tuberculous lymphadenitis.

Diagnosis of cervical tuberculous lymphadenitis (CTL), the most commonly occurring form of extrapulmonary tuberculosis, remains as a challenge in clinic. Detection of the presence of Mycobacterium tuberculosis (Mtb) in fine needle aspiration cytology (FNAC) samples is one golden criterion to confirm the CTL diagnosis. Due to the non-specific clinical presentation, CTL might be confused with other lymph node enlargement diseases; therefore empirical treatment with non-anti-TB antibiotics is often initially administered. However, it is still unclear whether this diagnostic antibiotic treatment affects the positivity of Mtb detection in FNAC. The demographics and clinical characteristics of 732 lymph node enlargement patients who had underwent FNAC were retrospectively analyzed and 605 (82.65%) of them were diagnosed as CTL. A total of 279 CTL cases (279/605, 46.11%) with completion of three Mtb tests (AFB, NAAT, and Mtb culture) in FNAC samples were selected for analyzing the effect of empirical antibiotic treatment on the positivity of Mtb tests. Compared to CTL patients without antibiotic treatment prior to FNAC, patients received empirical non anti-TB treatment had significantly lower positivity for acid fast bacilli staining (adjusted OR 0.11, 95% CI 0.06-0.21), nucleic acid amplification test (NAAT) (adjusted OR 0.38, 95% CI 0.21-0.71), and Mtb culture (adjusted OR 0.11, 95% CI 0.06-0.19). In conclusion, this study demonstrated that empirical non anti-TB antibiotic treatment reduced the opportunity to confirm CTL by microbiological analysis. Patients with cervical lymph node enlargement should undergo FNAC for Mtb tests prior to initiation of empirical non anti-TB treatment.

Regulatory B cells in infectious disease (Review).

Regulatory B cells (Bregs) are a subset of B cells, which reportedly exert significant immunomodulatory effects through the production of interleukin (IL)­10, IL­35 and transforming growth factor­ß. Over the last decade, studies have indicated that Bregs function in autoimmune and allergic diseases through antigen­specific and non­specific immunoregulatory mechanisms. However, only a limited number of reviews have focused on the role of Bregs during infection, particularly their functions in intracellular infections. The present review discusses the role of Bregs in infectious diseases in animal models and human studies, and provides an overview of the immunoregulatory mechanisms used by Bregs.