Early Secreted Antigenic Target of 6-kDa of Mycobacterium tuberculosis Stimulates IL-6 Production by Macrophages through Activation of STAT3

Meprin β activity modulates cellular proliferation via trans-signaling IL-6-mediated AKT/ERK pathway in IR-induced kidney injury

Inflammation plays a central role in the progression of kidney injury induced by ischemia/reperfusion (IR). Meprin metalloproteinases have been implicated in the pathophysiology of IR-induced kidney injury. Existing data from in vitro and in vivo studies show that meprins modulate interleukin-6 (IL-6)-mediated inflammation via proteolytic processing of IL-6 and its receptor. IL-6 trans-signaling induces proliferation through either MAPK/ERK or PI3K/AKT pathway or in crosstalk with AKT/ERK. We previously showed that meprin β modulates cellular survival (BCL-2) through IL-6/JAK/STAT signaling pathway in IR-induced kidney injury. However, it's not known how meprin β modulation of the IL-6 signaling pathway impacts the cellular proliferation in IR-induced acute kidney injury. The goal of the current study was to determine how meprin β modulation of the IL-6 signaling pathway impacts downstream cellular proliferation in IR-induced kidney injury. We used the unilateral IR as a model of renal inflammation in wild-type (WT) and meprin β knockout (βKO) mice, with the contralateral kidneys serving as controls. The mice were sacrificed at 96 h post-IR, and kidney tissue processed for evaluation by RT-PCR and immunohistochemistry. Statistical analysis utilized two-way ANOVA. RT-PCR data showed a significant increase in mRNA levels for IL-6 and proliferating cell nuclear antigen (PCNA) in WT and βKO mice at 96 h-post IR when compared to WT control kidneys. However, the baseline mRNA levels for PCNA were significantly higher in βKO when compared to WT kidneys. Immunohistochemical data showed significant increases in IL-6, PCNA, p-AKT and p-ERK in select tubules in both genotypes at 96 h post-IR when compared to control kidneys for each genotype. Data from immunofluorescence counterstaining of kidney tissues revealed that at 96 hours post-IR, IL-6, PCNA, p-AKT, and p-ERK were primarily expressed in meprin β-expressing proximal tubules (PTs), where meprins are abundantly present. However, high levels of IL-6 were also present in the lumen of PTs and DTs from WT and βKO kidneys at 96 h post-IR, suggesting increased release/shedding into filtrate and subsequently into urine. In conclusion, this study highlights the role of meprin β activity in regulating cellular proliferation through PCNA regulation, driven by the IL-6-mediated AKT/ERK signaling pathway during the recovery phase following IR-induced kidney injury.

Immunogenicity and protective efficacy of a multi-antigenic adenovirus-based vaccine candidate against Mycobacterium tuberculosis

Introduction

The inadequate efficacy of the Bacillus Calmette-Guérin (BCG) vaccine against adult pulmonary tuberculosis (TB) necessitates the development of new and effective vaccines. Human adenovirus serotype 5 (Ad5), which induces T-cell response, is a widely used viral vector. In this study, we aimed to evaluate the efficacy of a multi-antigenic recombinant Ad5 vectored vaccine and determine the optimal immunization route for enhanced immune response against Mycobacterium tuberculosis.

Methods

We constructed a multi-antigenic recombinant Ad5 vectored vaccine expressing four antigens (Ag85B-ESAT6-MPT64-Rv2660c) of M. tuberculosis (rAd-TB4), immunized with rAd-TB4 (5 × 107 infectious virus units/mouse) twice at an interval of 4 weeks starting at 10 weeks after BCG priming, and evaluated its boosting efficacy in a BCG-primed mouse model, and determined the optimal immunization route.

Results

Compared with the BCG-only (2 × 105 colony forming units/mouse), subcutaneous injection of rAd-TB4 (1 × 107 infectious virus units/mL; two doses) elicited a T-cell response and cytokine production in lung lymphocytes and splenocytes. rAd-TB4 immunization significantly reduced bacterial loads and inflamed lung areas compared to BCG immunization (p < 0.01) and protected against the H37Rv challenge performed at 17 weeks of BCG priming. RNA sequencing of the whole blood of rAd-TB4-vaccinated mice collected pre- and, 1 and 4 weeks post-infection, identified differentially expressed genes associated with immune and inflammatory responses, especially those in the Wnt signaling pathway.

Conclusion

Our results indicate that rAd-TB4 immunization enhances the immune response to the vaccine boosting antigens in BCG-primed mice, making it a potential adult pulmonary TB vaccine candidate.

Heterogeneity and interplay: the multifaceted role of cancer-associated fibroblasts in the tumor and therapeutic strategies

The journey of cancer development is a multifaceted and staged process. The array of treatments available for cancer varies significantly, dictated by the disease's type and stage. Cancer-associated fibroblasts (CAFs), prevalent across various cancer types and stages, play a pivotal role in tumor genesis, progression, metastasis, and drug resistance. The strategy of concurrently targeting cancer cells and CAFs holds great promise in cancer therapy. In this review, we focus intently on CAFs, delving into their critical role in cancer's progression. We begin by exploring the origins, classification, and surface markers of CAFs. Following this, we emphasize the key cytokines and signaling pathways involved in the interplay between cancer cells and CAFs and their influence on the tumor immune microenvironment. Additionally, we examine current therapeutic approaches targeting CAFs. This article underscores the multifarious roles of CAFs within the tumor microenvironment and their potential applications in cancer treatment, highlighting their importance as key targets in overcoming drug resistance and enhancing the efficacy of tumor therapies.

Impact of in-utero exposure to HIV and latent TB on infant humoral responses

Introduction

Latent tuberculosis infection (LTBI) is a common coinfection in people living with HIV (PWH). How LTBI and HIV exposure in utero influence the development of infant humoral immunity is not well characterized. To address this question, we assessed the relationship between maternal humoral responses in pregnant women with HIV or with HIV/LTBI on humoral responses in infants to BCG vaccination and TB acquisition.

Methods

Plasma samples were obtained from mother infant pairs during pregnancy (14-34 wks gestation) and in infants at 12 and 44 wks of age from the IMPAACT P1078 clinical trial. LTBI was established by Interferon gamma release assay (IGRA). Progression to active TB (ATB) disease was observed in 5 women at various times after giving birth. All infants were BCG vaccinated at birth and tested for IGRA at 44 weeks. Mtb (PPD, ESAT6/CFP10, Ag85A, LAM), HIV (GP120), and Influenza (HA) specific IgG, IgM, and IgA were measured in plasma samples using a bead based Luminex assay with Flexmap 3D.

Results

In maternal plasma there were no differences in Mtb-specific antibodies or viral antibodies in relation to maternal IGRA status. ATB progressors showed increases in Mtb-specific antibodies at diagnosis compared to study entry. However, when compared to the non-progressors at entry, progressors had higher levels of Ag85A IgG and reduced ESAT6/CFP10 IgG and LAM IgG, IgM, and IgA1. All infants showed a decrease in IgG to viral antigens (HIV GP120 and HA) from 12 to 44 weeks attributed to waning of maternally transferred antibody titers. However, Mtb-specific (PPD, ESAT6/CFP10, Ag85A, and LAM) IgG and IgM increased from 12 to 44 weeks. HIV and HA IgG levels in maternal and 12-week infant plasma were highly correlated, and ESAT6/CFP10 IgG and LAM IgG showed a relationship between maternal and infant Abs. Finally, in the subset of infants that tested IGRA positive at 44 weeks, we observed a trend for lower LAM IgM compared to IGRA- infants at 44 weeks.

Discussion

The results from our study raise the possibility that antibodies to LAM are associated with protection from progression to ATB and support further research into the development of humoral immunity against TB through infection or vaccination.

Enhancing the sequence coverage of nanodiamond-extracted early secretory proteins from the Mycobacterium tuberculosis complex

The unambiguous identification of protein species requires high sequence coverage. In this study, we successfully improved the sequence coverage of early secretory 10 kDa cell filtrate protein (CFP-10) and 6 kDa early secretory antigenic target (ESAT-6) proteins from the Mycobacterium tuberculosis complex (MTC) in broth culture media with the use of the 4-chloro-α-cyanocinnamic acid (Cl-CCA) matrix. Conventional matrices, α-cyano-hydroxy-cinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB), were also used for comparison. After nanodiamond (ND) extraction, the sequence coverage of the CFP-10 protein was 87% when CHCA and DHB matrices were used, and the ESAT-6 protein was not detected. On the other hand, the sequence coverage for ND-extracted CFP-10 and ESAT-6 could reach 94% and 100%, respectively, when the Cl-CCA matrix was used and with the removal of interference from bovine serum albumin (BSA) protein and α-crystallin (ACR) protein. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was also adopted to analyze the protein mass spectra. A total of 6 prominent ion signals were observed, including ESAT-6 protein peaks at mass-to-charge ratios (m/z) of ∼7931, ∼7974, ∼9768, and ∼9813 and CFP-10 protein peaks at m/z of ∼10 100 and ∼10 660. The ESAT-6 ion signals were always detected concurrently with CFP-10 ion signals, but CFP-10 ion signals could be detected alone without the ESAT-6 ion signals. Furthermore, the newly found ESAT-6 peaks were also confirmed using a Mag-Beads-Protein G kit with an ESAT-6 antibody to capture the ESAT-6 protein, which was also consistent with the sequence coverage analysis.

Host Cell Death and Modulation of Immune Response against Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), a prevalent infectious disease affecting populations worldwide. A classic trait of TB pathology is the formation of granulomas, which wall off the pathogen, via the innate and adaptive immune systems. Some key players involved include tumor necrosis factor-alpha (TNF-α), foamy macrophages, type I interferons (IFNs), and reactive oxygen species, which may also show overlap with cell death pathways. Additionally, host cell death is a primary method for combating and controlling Mtb within the body, a process which is influenced by both host and bacterial factors. These cell death modalities have distinct molecular mechanisms and pathways. Programmed cell death (PCD), encompassing apoptosis and autophagy, typically confers a protective response against Mtb by containing the bacteria within dead macrophages, facilitating their phagocytosis by uninfected or neighboring cells, whereas necrotic cell death benefits the pathogen, leading to the release of bacteria extracellularly. Apoptosis is triggered via intrinsic and extrinsic caspase-dependent pathways as well as caspase-independent pathways. Necrosis is induced via various pathways, including necroptosis, pyroptosis, and ferroptosis. Given the pivotal role of host cell death pathways in host defense against Mtb, therapeutic agents targeting cell death signaling have been investigated for TB treatment. This review provides an overview of the diverse mechanisms underlying Mtb-induced host cell death, examining their implications for host immunity. Furthermore, it discusses the potential of targeting host cell death pathways as therapeutic and preventive strategies against Mtb infection.

Gut microbiome, T cell subsets, and cytokine analysis identify differential biomarkers in tuberculosis

Introduction

The gut microbiota, T cell subsets, and cytokines participate in tuberculosis (TB) pathogenesis. To date, the mechanisms by which these factors interactively promote TB development at different time points remain largely unclear. In the context of this study, We looked into the microorganisms in the digestive tract, T cell types, and cytokines related to tuberculosis.

Methods

According to QIIME2, we analyzed 16SrDNA sequencing of the gut microbiome on the Illumina MiSeq. Enzyme-linked immunosorbent assay was used to measure the concentrations of cytokines.

Results

We showed the presence of 26 identifiable differential microbiomes in the gut and 44 metabolic pathways between healthy controls and the different time points in the development of TB in patients. Five bacterial genera (Bacteroides, Bifidobacterium, Faecalibacterium, Collinsella, and Clostridium) were most closely associated with CD4/CD8, whereas three bacterial taxa (Faecalibacterium, Collinsella, and Clostridium) were most closely associated with CD4. Three bacterial taxa (Faecalibacterium, Ruminococcus, and Dorea) were most closely associated with IL-4. Ruminococcus was most closely associated with IL-2 and IL-10.

Conclusion

Diverse microorganisms, subsets of T cells, and cytokines, exhibiting varying relative abundances and structural compositions, were observed in both healthy controls and patients throughout distinct phases of tuberculosis. Gaining insight into the function of the gut microbiome, T cell subsets, and cytokines may help modulate therapeutic strategies for TB.

BCG revaccination in adults enhances pro-inflammatory markers of trained immunity along with anti-inflammatory pathways

This study characterized mechanisms of Bacille Calmette-Guérin (BCG) revaccination-induced trained immunity (TI) in India. Adults, BCG vaccinated at birth, were sampled longitudinally before and after a second BCG dose. BCG revaccination significantly elevated tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6 in HLA-DR+CD16-CD14hi monocytes, demonstrating induction of TI. Mycobacteria-specific CD4+ T cell interferon (IFN) γ, IL-2, and TNF-α were significantly higher in re-vaccinees and correlated positively with HLA-DR+CD16-CD14hi TI responses. This, however, did not translate into increased mycobacterial growth control, measured by mycobacterial growth inhibition assay (MGIA). Post revaccination, elevated secreted TNF-α, IL-1β, and IL-6 to "heterologous" fungal, bacterial, and enhanced CXCL-10 and IFNα to viral stimuli were also observed concomitant with increased anti-inflammatory cytokine, IL-1RA. RNA sequencing after revaccination highlighted a BCG and LPS induced signature which included upregulated IL17 and TNF pathway genes and downregulated key inflammatory genes: CXCL11, CCL24, HLADRA, CTSS, CTSC. Our data highlight a balanced immune response comprising pro- and anti-inflammatory mediators to be a feature of BCG revaccination-induced immunity.

Advances of Long Non-Coding RNAs as Potential Biomarkers for Tuberculosis: New Hope for Diagnosis?

Tuberculosis (TB), one of the top ten causes of death globally induced by the infection of Mycobacterium tuberculosis (Mtb), remains a grave public health issue worldwide. With almost one-third of the world's population getting infected by Mtb, between 5% and 10% of these infected individuals are predicted to develop active TB disease, which would not only result in severe tissue damage and necrosis, but also pose serious threats to human life. However, the exact molecular mechanisms underlying the pathogenesis and immunology of TB remain unclear, which significantly restricts the effective control of TB epidemics. Despite significant advances in current detection technologies and treatments for TB, there are still no appropriate solutions that are suitable for simultaneous, early, rapid, and accurate screening of TB. Various cellular events can perturb the development and progression of TB, which are always associated with several specific molecular signaling events controlled by dysregulated gene expression patterns. Long non-coding RNAs (lncRNAs), a kind of non-coding RNA (ncRNA) with a transcript of more than 200 nucleotides in length in eukaryotic cells, have been found to regulate the expression of protein-coding genes that are involved in some critical signaling events, such as inflammatory, pathological, and immunological responses. Increasing evidence has claimed that lncRNAs might directly influence the susceptibility to TB, as well as the development and progression of TB. Therefore, lncRNAs have been widely expected to serve as promising molecular biomarkers and therapeutic targets for TB. In this review, we summarized the functions of lncRNAs and their regulatory roles in the development and progression of TB. More importantly, we widely discussed the potential of lncRNAs to act as TB biomarkers, which would offer new possibilities in novel diagnostic strategy exploration and benefit the control of the TB epidemic.

Tumor cell plasticity in targeted therapy-induced resistance: mechanisms and new strategies

Despite the success of targeted therapies in cancer treatment, therapy-induced resistance remains a major obstacle to a complete cure. Tumor cells evade treatments and relapse via phenotypic switching driven by intrinsic or induced cell plasticity. Several reversible mechanisms have been proposed to circumvent tumor cell plasticity, including epigenetic modifications, regulation of transcription factors, activation or suppression of key signaling pathways, as well as modification of the tumor environment. Epithelial-to-mesenchymal transition, tumor cell and cancer stem cell formation also serve as roads towards tumor cell plasticity. Corresponding treatment strategies have recently been developed that either target plasticity-related mechanisms or employ combination treatments. In this review, we delineate the formation of tumor cell plasticity and its manipulation of tumor evasion from targeted therapy. We discuss the non-genetic mechanisms of targeted drug-induced tumor cell plasticity in various types of tumors and provide insights into the contribution of tumor cell plasticity to acquired drug resistance. New therapeutic strategies such as inhibition or reversal of tumor cell plasticity are also presented. We also discuss the multitude of clinical trials that are ongoing worldwide with the intention of improving clinical outcomes. These advances provide a direction for developing novel therapeutic strategies and combination therapy regimens that target tumor cell plasticity.

Characterization of chemokine and cytokine expression pattern in tuberculous lymphadenitis patient

INTRODUCTION

C-C chemokine receptor-2 (CCR-2) and C-C chemokine ligand-5 (CCL-5) play an important role in the migration of monocytes, macrophages, dendritic cells, and activated T cells against Mycobacterium tuberculosis (M.tb). Meanwhile, signal transducer and activator of transcription 3 (STAT-3) and suppressor of cytokine signaling 3 (SOCS-3), activated by interleukin (IL)-6 and IL-10 in tuberculosis (TB) infection, play an important role in phagocytosis, inflammation, and granulomatous-forming processes that may lead to TB treatment success or failure. However, there are no data about the expression of those markers in tuberculous lymphadenitis. The characterization of those markers is very critical to put a fundamental basis to understand the homing mechanism of tuberculous lymphadenitis.

AIM OF STUDY

The specific objective of this study is to characterize the expression pattern of CCR-2-CCL-5, IL-6, IL-10, STAT-3, and SOCS-3 in tuberculous lymphadenitis.

METHODS

The study was performed on 27 cases of tuberculous lymphadenitis node biopsies. The diagnosis of tuberculous lymphadenitis was based on the clinical criteria and the presence of the histological feature characteristic of TB granulomas. Afterward, immunohistochemistry was stained with CCR-2, CCL-5, IL-6, IL-10, STAT-3, and SOCS-3. A semiquantitative analysis of IHC images was performed to examine protein expression in stained preparations. The expression was also manually counted.

RESULTS

Compared with the normal area, both lymphocytes and macrophages expressed strongly CCR-2-, CCL-5, and IL-6, while IL-10, STAT-3-, and SOCS-3- were expressed lowly. There was a strong positive correlation between CCR-2 with IL-6 (p = 0,83) and IL-10 (p = 0,83).

CONCLUSION

The chronic infection process of tuberculous lymphadenitis was characterized by the expression of IL-10low, STAT-3low, SOCS-3low, CCR-2high, CCL-5high, and IL-6high.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov, identifier NCT05202548.

Histone Deacetylase-2 Controls IL-1β Production through the Regulation of NLRP3 Expression and Activation in Tuberculosis Infection

Histone deacetylases (HDACs) are critical immune regulators. However, their roles in interleukin-1β (IL-1β) production remain unclear. By screening 11 zinc-dependent HDACs with chemical inhibitors, we found that HDAC1 inhibitor, 4-(dimethylamino)-N-[6-(hydroxyamino)-6-oxohexyl]-benzamide (DHOB), enhanced IL-1β production by macrophage and dendritic cells upon TLR4 stimulation or Mycobacterium tuberculosis infection through IL-1β maturation via elevated NLRP3 expression, increased cleaved caspase-1, and enhanced ASC oligomerization. DHOB rescued defective IL-1β production by dendritic cells infected with M. tuberculosis with ESAT-6 deletion, a virulence factor shown to activate NLRP3 inflammasome. DHOB increased IL-1β production and NLRP3 expression in a tuberculosis mouse model. Although DHOB inhibited HDAC activities of both HDAC1 and HDAC2 by direct binding, knockdown of HDAC2, but not HDAC1, increased IL-1β production and NLRP3 expression in M. tuberculosis-infected macrophages. These data suggest that HDAC2, but not HDAC1, controls IL-1β production through NLRP3 inflammasome activation, a mechanism with a significance in chronic inflammatory diseases including tuberculosis.

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HDAC1 inhibitor, DHOB, increased IL-1β production via NLRP3 inflammasome activation

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DHOB suppressed deacetylase activities of both HDAC1 and HDAC2 by direct interaction

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Deletion of HDAC2, but not HDAC1, increased IL-β production by increased NLRP3 expression

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DHOB increased IL-1β and NLRP3 expression in a mouse model of TB infection

Sphingosine-1-phosphate receptors 2 and 3 reprogram resting human macrophages into M1 phenotype following mycobacteria infection

Mycobacteria tuberculosis (M.tb) the causative agent for tuberculosis has been accredited for a high rate of morbidity and mortality worldwide. The rise in MDR and XDR cases has further created new obstacles in achieving the "End TB Strategy", which is aimed for 2035. In this article, we have demonstrated the potential of sphingosine-1-phosphate (S1P) analogs in providing an anti-mycobacterial effector response by altering macrophage polarity into M1. Among S1PR1 and S1PR3 analogs, S1PR2 analogs proficiently favor selective polarization of infected human macrophages into M1 phenotypes, marked by increased expression of M1 markers and decreased M2 markers. Furthermore, S1PR1-3 analogs treated macrophages were also able to decrease the secretion of anti-inflammatory cytokine IL-10 and can induce NO secretion in infected macrophages. Lastly, only S1PR2-3 analogs were able to restrict the growth of mycobacteria in human macrophages. Taken together our study reflects the potential of S1PR2-3 analogs in providing host defenses following mycobacterial infection by favoring M1 macrophage polarization.

Early IL-17A production helps establish Mycobacterium intracellulare infection in mice

Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates of M. intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1-2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0-2 weeks) and late (32-34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs of M. intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover, in vitro data showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells upon M. intracellulare infection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonary M. intracellulare infection in mice, at least in part through MMP-3 production.

Ibrutinib reverses IL-6-induced osimertinib resistance through inhibition of Laminin α5/FAK signaling

Osimertinib, a 3rd generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), is the first-line standard-of-care for EGFR-mutant non-small cell lung cancer (NSCLC) patients, while acquired drug resistance will inevitably occur. Interleukin-6 (IL-6) is a keystone cytokine in inflammation and cancer, while its role in osimertinib efficacy was unknown. Here we show that clinically, plasma IL-6 level predicts osimertinib efficacy in EGFR mutant NSCLC patients. Highly increased IL-6 levels are found in patients with acquired resistance to osimertinib. Addition of IL-6 or exogenous overexpression of IL-6 directly induces osimertinib resistance. Proteomics reveals LAMA5 (Laminin α5) and PTK2, protein tyrosine kinase 2, also called focal adhesion kinase (FAK), are activated in osimertinib-resistant cells, and siRNA knockdown of LAMA5 or PTK2 reverses IL-6-mediated osimertinib resistance. Next, using a large-scale compound screening, we identify ibrutinib as a potent inhibitor of IL-6 and Laminin α5/FAK signaling, which shows synergy with osimertinib in osimertinib-resistant cells with high IL-6 levels, but not in those with low IL-6 levels. In vivo, this combination inhibits tumor growth of xenografts bearing osimertinib-resistant tumors. Taken together, we conclude that Laminin α5/FAK signaling is responsible for IL-6-induced osimertinib resistance, which could be reversed by combination of ibrutinib and osimertinib.

The resistance mechanism of osimertinib, a third-generation EGFR-TKI, is mediated by IL-6 and Laminin α5/FAK signaling. Ibrutinib combined with osimertinib is presented as a strategy for overcoming osimertinib acquired resistance in EGFR mutant NSCLC.

Potential of Mycobacterium tuberculosis chorismate mutase (Rv1885c) as a novel TLR4-mediated adjuvant for dendritic cell-based cancer immunotherapy

For clinical application by dendritic cell (DC)-based cancer immunotherapy, a proper adjuvant system to elicit a strong anticancer immune response is needed. Here, we investigated the potential of chorismate mutase (TBCM, Rv1885c), a putative Mycobacterium tuberculosis (TB) virulence factor, as an immunoadjuvant in DC-based tumor immunotherapy. First, we found that TBCM functionally activated DCs by upregulating costimulatory molecules, increasing the secretion of proinflammatory cytokines, enhancing migration and inducing the Th1-type immune response in a dose-dependent manner via TLR4-mediated signaling. In addition, subcutaneous injection of TBCM-activated DCs loaded with cell lysates led to reduced tumor mass, enhanced mouse survival and lowered tumor incidence in lung carcinoma (LLC) cell-bearing mice. This is mainly mediated by functional cytotoxic T lymphocyte-mediated oncolytic activity and inhibition of cancer proliferation- and metastasis-related genes. Moreover, TBCM-induced DCs can also generate memory CD4 T cells and exert long-term tumor prevention effects. In conclusion, our findings suggest that TBCM (Rv1885c), a novel TLR4 agonist, could be used as an immunoadjuvant for DC-based cancer immunotherapy.

The role played by bacterial infections in the onset and metastasis of cancer

Understanding various responses of cells towards change in their external environment, presence of other species and is important in identifying and correlating the mechanisms leading to malignant transformations and cancer development. Although uncovering and comprehending the association between bacteria and cancer is highly challenging, it promises excellent perspectives and approaches for successful cancer therapy. This review introduces various bacterial species, their virulence factors, and their role in cell transformations leading to cancer (particularly gastric, oral, colon, and breast cancer). Bacterial dysbiosis permutates host cells, causes inflammation, and results in tumorigenesis. This review explored bacterial-mediated host cell transformation causing chronic inflammation, immune receptor hyperactivation/absconding immune recognition, and genomic instability. Bacterial infections downregulate E-cadherin, leading to loosening of epithelial tight junction polarity and triggers metastasis. In addition to understanding the role of bacterial infections in cancer development, we have also reviewed the application of bacteria for cancer therapy. The emergence of bacteriotherapy combined with conventional therapies led to new and effective ways of overcoming challenges associated with available treatments. This review discusses the application of bacterial minicells, microswimmers, and outer cell membrane vesicles (OMV) for drug delivery applications.

Exaggerated IL-17A activity in human in vivo recall responses discriminates active tuberculosis from latent infection and cured disease

Host immune responses at the site of Mycobacterium tuberculosis (Mtb) infection can mediate pathogenesis of tuberculosis (TB) and onward transmission of infection. We hypothesized that pathological immune responses would be enriched at the site of host-pathogen interactions modelled by a standardized tuberculin skin test (TST) challenge in patients with active TB compared to those without disease, and interrogated immune responses by genome-wide transcriptional profiling. We show exaggerated interleukin (IL)-17A and Th17 responses among 48 individuals with active TB compared to 191 with latent TB infection, associated with increased neutrophil recruitment and matrix metalloproteinase-1 expression, both involved in TB pathogenesis. Curative antimicrobial treatment reversed these observed changes. Increased IL-1β and IL-6 responses to mycobacterial stimulation were evident in both circulating monocytes and in molecular changes at the site of TST in individuals with active TB, supporting a model in which monocyte-derived IL-1β and IL-6 promote Th17 differentiation within tissues. Modulation of these cytokine pathways may provide a rational strategy for host-directed therapy in active TB.

The potential impacts of early secreted antigenic target of 6 kDa of Mycobacterium tuberculosis on KSHV-infected cells

Kaposi's sarcoma-associated herpesvirus (KSHV) causes several human cancers, including Kaposi's sarcoma (KS) and primary effusion lymphoma, which are mostly seen in immunocompromised patients, such as human immunodefeciency virus (HIV)+ individuals. Tuberculosis (TB), caused by the bacterial pathogen Mycobacterium tuberculosis (Mtb), remains one of the deadliest infectious diseases in the world. The risk of developing TB is dramatically higher in people living with HIV than among those without HIV infection. Case reports link cutaneous or pulmonary KS in HIV+ patients with mycobacterial co-infections, however, impacts of Mtb infection or its products on KSHV-infected cells are not known. We report here that ESAT-6, a secreted Mtb virulence factor, induces viral reactivation from KSHV-infected cells. KSHV-infected pulmonary endothelial cells were resistant to ESAT-6 induced inhibition of cell growth. Our data demonstrate that Mtb virulence factors influence the biology of KSHV-infected cells, highlighting the need to study the interactions between these two pathogens commonly found in people living with HIV.

Influence of NOD-like receptor 2 gene polymorphisms on muramyl dipeptide induced pro-inflammatory response in patients with active pulmonary tuberculosis and household contacts

PURPOSE

The immune response induced by nucleotide-binding oligomerization domain-2(NOD2) is associated with the production of cytokines affected by the host's genetic background. The present study aimed to examine the effects of NOD2; 802C > T, 2105G > A polymorphisms associated with altered cytokine levels in patients with active pulmonary tuberculosis disease, Latent TB subjects (household contacts(HHC) and healthy controls(HC).

METHODS

Genetic polymorphisms were analyzed by Restriction Fragment Length Polymorphism(RFLP) in 102-PTB patients, 102-HHC, and 132-HC. QuantiFERON-TB Gold In-Tube test was performed to identify latent TB infection in 60-HHC. Estimated their cytokine levels by ELISA in MDP (muramyl dipeptide) stimulated culture supernatants of all the groups. Further, we studied pre-mRNA structures by insilico analysis and relative gene expression by RT-PCR.

RESULTS

Recessive genetic models of NOD2 802C > T SNP with TT genotype and AA genotype of NOD2 2105G > A SNP were significantly associated with increased TB risk in PTB patients and HHC compared with HC. In vitro stimulations were performed with NOD2 ligand MDP in PTB patients and latent TB subjects: QuantiFERON positive household contacts (QFT + ve HHC)and QuantiFERON negative household contacts(QFT-ve HHC). The results showed that reduced TNF-α and enhanced IL-12, IL-1β indicate that these cytokines may play an essential role in the initial maintenance of cell-mediated immunity. Our study demonstrated the correlation between NOD2 polymorphism with IL-1β, TNF-α, IL-12 levels. Insilico analysis represents the pre-mRNA secondary structures affected by NOD2 SNPs. We also observed the difference in m RNA levels in variant and wild genotypes.

CONCLUSION

This finding may lead to the forthcoming development of immunotherapy and may be used as predictive markers to identify high-risk individuals for TB disease.

Mycobacterium tuberculosis stimulates IL-1β production by macrophages in an ESAT-6 dependent manner with the involvement of serum amyloid A3

Despite its critical roles in immune responses against tuberculosis infection and immune pathology, the molecular details of interleukin (IL)-1β production in tuberculosis infection remain elusive. To explore IL-1β production in tuberculosis infection, we infected mouse bone marrow-derived macrophages (BMDM) with Mycobacterium tuberculosis (Mtb) H37Rv, its early secreted antigenic target protein of 6 kDa (ESAT-6) gene deletion (H37Rv:Δ3875) or complemented strain (H37Rv:Δ3875C) and evaluated IL-1β production. H37Rv induced significantly increased IL-1β production by BMDMs compared to non-infected BMDMs. In contrast, H37Rv:Δ3875 induced significantly less mature IL-1β production despite eliciting comparable levels of pro-IL-1β and IL-8 from BMDMs compared to H37Rv and H37Rv:Δ3875C. Blocking either NLRP3 or K⁺ efflux diminished H37Rv-induced IL-1β production by BMDMs. Infection of mice intranasally with H37Rv:Δ3875 induced less IL-1β production in the lungs compared with H37Rv. Intranasal delivery of ESAT-6 but not CFP10 induced production of IL-1β in mouse lungs and RNA-Seq analysis identified serum amyloid A (SAA) 3 as one of the highly expressed genes in mouse lungs. Infection of mice with H37Rv but not H37Rv:Δ3875 induced expression of lung SAA3 mRNA and protein, consistent with the effect of intranasal delivery of ESAT-6. Silencing SAA3 reduced Mtb-induced IL-1β production by BMDMs. We conclude that SAA3 plays critical role in ESAT-6 dependent IL-1β production by macrophages in tuberculosis infection.

Triptolide Modulates the Expression of Inflammation-Associated lncRNA-PACER and lincRNA-p21 in Mycobacterium tuberculosis-Infected Monocyte-Derived Macrophages

Triptolide is a diterpene triepoxide, which performs its biological activities via mechanisms including induction of apoptosis, targeting of pro-inflammatory cytokines, and reshaping of the epigenetic landscape of target cells. However, the targeting of long non-coding RNAs (lncRNAs) by triptolide has not yet been investigated, despite their emerging roles as key epigenetic regulators of inflammation and immune cell function during Mycobacterium tuberculosis (Mtb) infection. Hence, we investigated whether triptolide targets inflammation-associated lncRNA-PACER and lincRNA-p21 and how this targeting associates with Mtb killing within monocyte-derived macrophages (MDMs).Using RT-qPCR, we found that triptolide induced the expression of lincRNA-p21 but inhibited the expression of lncRNA-PACER in resting MDMs in a dose- and time-dependent manner. Moreover, Mtb infection induced the expression of lincRNA-p21 and lncRNA-PACER, and exposure to triptolide before or after Mtb infection led to further increase of Mtb-induced expression of these lncRNAs in MDMs. We further found that contrary to lncRNA-PACER, triptolide time- and dose-dependently upregulated Ptgs-2, which is a proximal gene regulated by lncRNA-PACER. Also, low-concentration triptolide inhibited the expression of cytokine IL-6, a known target of lincRNA-p21. Mtb infection induced the expression of IL-6 and Ptgs-2, and triptolide treatment further increased IL-6 but decreased Ptgs-2 expression in Mtb-infected MDMs. The inverse relation between the expression of these lncRNAs and their target genes is concordant with the conception that these lncRNAs mediate, at least partially, the cytotoxic and/or anti-inflammatory activities of triptolide in both resting and activated MDMs. Using the CFU count method, we found that triptolide decreased the intracellular growth of Mtb HN878. The alamarBlue assay showed that this decreased Mtb HN878 growth was not as a result of direct targeting of Mtb HN878 by triptolide, but rather evoking MDMs’ intracellular killing mechanisms which we speculate could include triptolide-induced enhancement of MDMs’ effector killing functions mediated by lncRNA-PACER and lincRNA-p21. Altogether, these results provide proof of the modulation of lncRNA-PACER and lincRNA-p21 expression by triptolide, and a possible link between these lncRNAs, the enhancement of MDMs’ effector killing functions and the intracellular Mtb-killing activities of triptolide. These findings prompt for further investigation of the precise contribution of these lncRNAs to triptolide-induced activities in MDMs.

Subunit Vaccine ESAT-6:c-di-AMP Delivered by Intranasal Route Elicits Immune Responses and Protects Against Mycobacterium tuberculosis Infection

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infection, remains the most common cause of death from a single infectious disease. More safe and effective vaccines are necessary for preventing the prevalence of TB. In this study, a subunit vaccine of ESAT-6 formulated with c-di-AMP (ESAT-6:c-di-AMP) promoted mucosal and systemic immune responses in spleen and lung. ESAT-6:c-di-AMP inhibited the differentiations of CD8⁺ T cells as well as macrophages, but promoted the differentiations of ILCs in lung. The co-stimulation also enhanced inflammatory cytokines production in MH-S cells. It was first revealed that ESAT-6 and c-di-AMP regulated autophagy of macrophages in different stages, which together resulted in the inhibition of Mtb growth in macrophages during early infection. After Mtb infection, the level of ESAT-6-specific immune responses induced by ESAT-6:c-di-AMP dropped sharply. Finally, inoculation of ESAT-6:c-di-AMP led to significant reduction of bacterial burdens in lungs and spleens of immunized mice. Our results demonstrated that subunit vaccine ESAT-6:c-di-AMP could elicit innate and adaptive immune responses which provided protection against Mtb challenge, and c-di-AMP as a mucosal adjuvant could enhance immunogenicity of antigen, especially for innate immunity, which might be used for new mucosal vaccine against TB.

Saussureae Radix Attenuates Neuroinflammation in LPS-Stimulated Mouse BV2 Microglia via HO-1/Nrf-2 Induction and Inflammatory Pathway Inhibition

The activation of microglial cells and their subsequent neuroinflammatory reactions are related to various degenerative brain diseases. Therefore, the regulation of microglial cell activation is an important point for the research of therapeutic agents for treating or preventing neurodegenerative disorders. Saussureae Radix (SR) is the root of Saussurea lappa Clarke, and it has been used for a long time as an herbal medicine in East Asia to treat indigestion and inflammation of the digestive system. In previous studies, however, the effect of SR ethanolic extract on microglial cell-mediated neuroinflammation was not fully explained. In this study, we explored the antineuroinflammatory activities and molecular mechanisms of SR in microglial cells stimulated with LPS (lipopolysaccharide). Our results illustrated that SR does not cause cytotoxicity and significantly weakens the production of nitric oxide (NO) and inflammatory cytokines. SR treatment also inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase- (COX-) 2, induced heme oxygenase- (HO-) 1, and activated the nuclear factor erythroid 2-related factor 2 (Nrf-2) pathway. In addition, SR significantly repressed the transcriptional activities of the nuclear factor- (NF-) κB and activator protein- (AP-) 1. Furthermore, SR effectively inhibited the phosphorylation of mitogen-activated protein kinase (MAPK) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT). Isolation and high-performance liquid chromatography (HPLC) analysis indicated two major sesquiterpenoids (costunolide and dehydrocostuslactone). These compounds significantly inhibited the production of neuroinflammatory mediators and induced HO-1 expression. These findings show that SR could be a potential candidate for the treatment of inflammation-related degenerative brain diseases.

Mycobacterium tuberculosis-Secreted Protein, ESAT-6, Inhibits Lipopolysaccharide-Induced MMP-9 Expression and Inflammation Through NF-κB and MAPK Signaling in RAW 264.7 Macrophage Cells

-20pt?>Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium that causes contagious tuberculosis (TB). Recently, Mtb-secreted proteins have been considered virulence factors and candidates for drugs and vaccines. Among these proteins, 6-kDa early secreted antigenic target (ESAT-6) is known to be able to induce component of matrix metalloproteinase-9 (MMP-9) in epithelial cells, leading to recruitment of macrophages. However, detailed function of ESAT-6 during macrophage recruitment to inflammatory sites remains unknown. Thus, the objective of the present study was to elucidate such function of EAST-6 and mechanism(s) involved. In the present study, we have found that recombinant ESAT-6 purified in the form of ESAT-6 double-connected structure (2E6D) could inhibit lipopolysaccharide (LPS)-induced potential of cell migration and inflammation in murine macrophage cells. Interestingly, 2E6D suppressed LPS-induced MMP-9 expression at both protein and mRNA levels as well as its enzyme activity. Levels of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) enzymes as known upregulators of MMP-9 were significantly decreased when 2E6D has been treated. In addition, nitric oxide (NO) as a second messenger was also significantly decreased by treatment with the purified 2E6D. Furthermore, 2E6D inhibited LPS-induced phosphorylation of IκB and translocation of NF-κB. Moreover, 2E6D suppressed phosphorylation of MAPK signaling proteins. Taken together, these results suggest that ESAT-6 can suppress LPS-induced MMP-9 and inflammation by downregulating COX-2, iNOS, and NO through NF-κB and MAPK signaling.

Role of inositol to improve surfactant functions and reduce IL-6 levels: A potential adjuvant strategy for SARS-CoV-2 pneumonia?

To date, the spread of SARS-CoV-2 infection is increasing worldwide and represents a primary healthcare emergency. Although the infection can be asymptomatic, several cases develop severe pneumonia and acute respiratory distress syndrome (ARDS) characterized by high levels of pro-inflammatory cytokines, primarily interleukin (IL)-6. Based on available data, the severity of ARDS and serum levels of IL-6 are key determinants for the prognosis. In this scenario, available in vitro and in vivo data suggested that myo-inositol is able to increase the synthesis and function of the surfactant phosphatidylinositol, acting on the phosphoinositide 3-kinase (PI3K)-regulated signaling, with amelioration of both immune system and oxygenation at the bronchoalveolar level. In addition, myo-inositol has been found able to decrease the levels of IL-6 in several experimental settings, due to an effect on the inositol-requiring enzyme 1 (IRE1)-X-box-binding protein 1 (XBP1) and on the signal transducer and activator of transcription 3 (STAT3) pathways. In this scenario, treatment with myo-inositol may be able to reduce IL-6 dependent inflammatory response and improve oxygenation in patients with severe ARDS by SARS-CoV-2. In addition, the action of myo-inositol on IRE1 endonuclease activity may also inhibit the replication of SARS-CoV-2, as was reported for the respiratory syncytial virus. Since the available data are extremely limited, if this potential therapeutic approach will be considered valid in the clinical practice, the necessary future investigations should aim to identify the best dose, administration route (oral, intravenous and/or aerosol nebulization), and cluster(s) of patients which may get beneficial effects from this treatment.

Mycobacterium bovis and you: A comprehensive look at the bacteria, its similarities to Mycobacterium tuberculosis, and its relationship with human disease

While Mycobacterium tuberculosis is the primary cause of tuberculosis in people, multiple other mycobacteria are capable of doing so. With the World Health Organization's goal of a 90% reduction in tuberculosis by 2035, all tuberculous mycobacteria need to be addressed. Understanding not only the similarities, but importantly the differences between the different species is crucial if eradication is ever to be achieved. Mycobacterium bovis, while typically thought of as a disease of cattle, remains a possible source of human infection worldwide. Although this species' genome differs from Mycobacterium tuberculosis by only 0.05%, significant differences are present, creating unique challenges to address. This review focuses on features which distinguish this bacterium from Mycobacterium tuberculosis, including differences in origin, structure, environmental persistence, host preferences, infection and disease, host immune response, diagnostics and treatment.

TLT2 Suppresses Th1 Response by Promoting IL-6 Production in Monocyte Through JAK/STAT3 Signal Pathway in Tuberculosis

The function of triggering receptor expressed on myeloid cell-like transcript 2 (TLT2) has not been characterized and their role in pulmonary tuberculosis (TB) remains unclear. In this study, we found that surface TLT2 was up-regulated in human monocytes of patients with active TB compared to healthy subjects. In vitro, TLT2 expression was induced in human monocyte cell line THP-1 cells after bacillus Calmette-Guérin (BCG) or Mycobacterium tuberculosis (Mtb) H37Rv infection. Knockdown of TLT2 by siRNA transfection suppressed IL-6 expression, whereas over-expression of TLT2 increased IL-6 production in THP-1 cells infected by H37Rv. TLT2⁺CD14⁺ monocytes produced higher level of IL-6 compared to TLT2^– subset in active TB patients. Western blot and immunocoprecipitation revealed that TLT2 interacted with kinase JAK1/JAK2/Tyk2 to enhance STAT3 phosphorylation. Moreover, we showed that tyrosine residues 297 and 315 of TLT2 cytoplasmic domain were involved in STAT3 activation. In monocyte/CD4⁺ T cell co-culture assay, blockage of TLT2 fusion protein facilitated IFN-γ production by CD4⁺ T cells. Plate count assay showed that monocyte-mediated bacterial killing was promoted by TLT2 fusion protein. In vivo treatment with TLT-2 fusion protein reduced IL-6 production by macrophage but increased IFN-γ production by CD4⁺ T cell in H37Rv and BCG infected mice. Furthermore, TLT2 fusion protein attenuated inflammation, and reduced bacterial load in lung of infected mice. Together, these findings demonstrate that TLT2 negatively regulates Th1 response against mycobacterial infection, which promotes IL-6 production through JAK/STAT3 signal pathway.

TNF deficiency dysregulates inflammatory cytokine production, leading to lung pathology and death during respiratory poxvirus infection

Excessive tumor necrosis factor (TNF) is known to cause significant pathology. Paradoxically, deficiency in TNF (TNF^-/-) also caused substantial pathology during respiratory ectromelia virus (ECTV) infection, a surrogate model for smallpox. TNF^-/- mice succumbed to fulminant disease whereas wild-type mice, and those engineered to express only transmembrane TNF (mTNF), fully recovered. TNF deficiency did not affect viral load or leukocyte recruitment but caused severe lung pathology and excessive production of the cytokines interleukin (IL)-6, IL-10, transforming growth factor beta (TGF-β), and interferon gamma (IFN-γ). Short-term blockade of these cytokines significantly reduced lung pathology in TNF^-/- mice concomitant with induction of protein inhibitor of activated STAT3 (PIAS3) and/or suppressor of cytokine signaling 3 (SOCS3), factors that inhibit STAT3 activation. Consequently, inhibition of STAT3 activation with an inhibitor reduced lung pathology. Long-term neutralization of IL-6 or TGF-β protected TNF^-/- mice from an otherwise lethal infection. Thus, mTNF alone is necessary and sufficient to regulate lung inflammation but it has no direct antiviral activity against ECTV. The data indicate that targeting specific cytokines or cytokine-signaling pathways to reduce or ameliorate lung inflammation during respiratory viral infections is possible but that the timing and duration of the interventive measure are critical.

The ESX-1 Virulence Factors Downregulate miR-147-3p in Mycobacterium marinum-Infected Macrophages

As important virulence factors of Mycobacterium tuberculosis, EsxA and EsxB not only play a role in phagosome rupture and M. tuberculosis cytosolic translocation but also function as modulators of host immune responses by modulating numerous microRNAs (miRNAs). Recently, we have found that mycobacterial infection downregulated miR-148a-3p (now termed miR-148) in macrophages in an ESX-1-dependent manner. The upregulation of miR-148 reduced mycobacterial intracellular survival. Here, we investigated miR-147-3p (now termed miR-147), a negative regulator of inflammatory cytokines (e.g., interleukin-6 [IL-6] and IL-10), in mycobacterial infection. We infected murine RAW264.7 macrophages with Mycobacterium marinum, a surrogate model organism for M. tuberculosis, and found that the esxBA-knockout strain (M. marinum ΔesxBA) upregulated miR-147 to a level that was significantly higher than that induced by the M. marinum wild-type (WT) strain or by the M. marinum ΔesxBA complemented strain, M. marinum ΔesxBA/pesxBA, suggesting that the ESX-1 system (potentially EsxBA and/or other codependently secreted factors) is the negative regulator of miR-147. miR-147 was also downregulated by directly incubating the macrophages with the purified recombinant EsxA or EsxB protein or the EsxBA heterodimer, which further confirms the role of the EsxBA proteins in the downregulation of miR-147. The upregulation of miR-147 inhibited the production of IL-6 and IL-10 and significantly reduced M. marinum intracellular survival. Interestingly, inhibitors of either miR-147 or miR-148 reciprocally compromised the effects of the mimics of their counterparts on M. marinum intracellular survival. This suggests that miR-147 and miR-148 share converged downstream pathways in response to mycobacterial infection, which was supported by data indicating that miR-147 upregulation inhibits the Toll-like receptor 4/NF-κB pathway.

Early secreted antigenic target 6-kDa from Mycobacterium tuberculosis enhanced the protective innate immunity of macrophages partially via HIF1α

Early secreted antigenic target 6-kDa protein (ESAT6) is an essential virulence factor of Mycobacterium tuberculosis (MTb). However, ESAT6 helped fighting MTb infection according to vaccine studies. It's unclear whether ESAT6 confers protection via enhancing the innate immunity of macrophages, which are the first-line defense against MTb. We profiled the global transcriptional changes and characterized the innate immunity of THP-1 macrophages treated with ESAT6. We found ESAT6 promoted the phagocytosis ability, enhanced reactive oxygen species (ROS) generation and accelerated glucose metabolism in macrophages. Meanwhile, ESAT6 induced a distinctive phenotype of macrophages with a concurrence of pro-inflammatory and anti-inflammatory cytokines and chemokines. ESAT6 increased the expression of HIF1α mRNA and protein. Interfering HIF1α with siRNA defected the capacity of phagocytosis and ROS generation as well as glucose metabolism. Thus, ESAT6 enhanced the protective innate immunity of macrophages partially via HIF1α. This study provided clues for developing therapies against tuberculosis by targeting ESAT6.

Early secreted antigenic target of 6-kDa of Mycobacterium tuberculosis induces transition of macrophages into epithelioid macrophages by downregulating iNOS / NO-mediated H3K27 trimethylation in macrophages

BACKGROUND

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (Mtb). Granuloma is a pathological feature of tuberculosis and is a tight immune cell aggregation caused by Mtb. The main constituent cells are macrophages and their derivative cells including epithelioid macrophages. However, the molecular mechanism of the transition has not been reported. The purpose of this study was to investigate whether early secreted antigenic target of 6-kDa (ESAT6) can induce the transition of bone marrow-derived macrophages (BMDMs) into epithelioid macrophages and its possible molecular mechanism.

METHODS

The recombinant ESAT6 protein was obtained from E.coli carrying esat6 gene after isopropyl β-d-thiogalactopyranoside (IPTG) induction. BMDMs were isolated from bone marrow of mice hind legs. Cells viability was detected by Cell Counting Kit 8 (CCK8) assays. The expression levels of mRNA and proteins were detected by qPCR and Western blot, or evaluated by flow cytometry. The expression level of nitric oxide (NO) was measured with a nitric oxide indicator.

RESULTS

ESAT6 could significantly induce mRNA and protein expression levels of a group of epithelioid macrophages marker molecules (EMMMs), including E-cadherin, junction plakoglobin, ZO1, desmoplakin, desmoglein3 and catenin porteins, in BMDMs. These events could be abrogated in macrophage from TLR2 deficiency mice. ESAT6 could also markedly induce iNOS/NO production that could significantly inhibit trimethylation of H3K27 in the cells. ESAT6-induced expressions of epithelioid macrophages marker molecules were significantly inhibited in the presence of H3K27 histone demethylase inhibitor GSK J1. Furthermore, ROS scavenging agent N,N'-Dimethylthiourea (DMTU) could markedly inhibit the transition induced by ESAT6 in macrophages.

CONCLUSION

This study demonstrates that ESAT6 bound with TLR2 can activate iNOS/NO and ROS signalings to reduce the trimethylation of H3K27 resulting in the increment of EMMMs expression that is beneficial to the transition of macrophages into epithelioid macrophages. However, hypoxia can inhibit this transition event. This study has provided new evidence of pathogenesis of granuloma caused by Mtb and also proposed new ideas for the treatment of TB.

Hoveniae Semen Seu Fructus Ethanol Extract Exhibits Anti-Inflammatory Activity via MAPK, AP-1, and STAT Signaling Pathways in LPS-Stimulated RAW 264.7 and Mouse Peritoneal Macrophages

Hoveniae semen seu fructus (HSF, fruit and seed of Hovenia dulcis Thunb) is an important traditional herbal medicine and food supplement in East Asia for the treatment of liver diseases, alcohol poisoning, obesity, allergy, and cancer. HSF has also been reported to have anti-inflammatory activity, but the cellular mechanism of action is not fully understood. We assessed the anti-inflammatory properties of an HSF ethanol (HSFE) extract and explored its precise mechanism. The ability of HSFE to suppress inflammatory responses was investigated in a murine macrophage cell line, RAW 264.7, and mouse primary macrophages. Secretions of NO, proinflammatory cytokines, inflammatory factors, and related proteins were measured using the Griess assay, ELISA, Western blot analysis, and real-time PCR, respectively. In addition, the main components of HSFE were analyzed by HPLC, and their anti-inflammatory activity was confirmed. Our results showed that pretreatment of HSFE markedly reduced the expression of NO and iNOS without causing cytotoxicity and significantly attenuated secretion of proinflammatory cytokines, including TNF-α, IL-6, and IL-1β. In addition, HSFE strongly suppressed phosphorylation of MAPK and decreased the activation of AP-1, JAK2/STAT, and NF-κB in LPS-stimulated RAW 264.7 cells in a concentration-dependent manner. Furthermore, HSFE strongly suppressed the inflammatory cytokine levels in mouse peritoneal macrophages. Also, as a result of HPLC analysis, three main components, ampelopsin, taxifolin, and myricetin, were identified in the HSFE extract, and each compound effectively inhibited the secretion of inflammatory mediators induced by LPS. These findings show that HSFE exerts anti-inflammatory effects by suppressing the activation of MAPK, AP-1, JAK2/STAT, and NF-κB signaling pathways in LPS-stimulated macrophages. In addition, the anti-inflammatory efficacy of HSFE appears to be closely related to the action of the three main components. Therefore, HSFE appears to be a promising candidate for the treatment of inflammatory diseases.

Curdlan Limits Mycobacterium tuberculosis Survival Through STAT-1 Regulated Nitric Oxide Production

Host-directed therapies have emerged as an innovative and promising approach in tuberculosis (TB) treatment due to the observed limitations of current TB regimen such as lengthy duration and emergence of drug resistance. Thus, we explored the role of curdlan (beta glucan polysaccharide) as a novel strategy to activate macrophages against Mycobacterium tuberculosis (Mtb). The aim of the study was to investigate the role of curdlan in restricting the Mtb growth both in vitro and in vivo. Further, the immunomodulatory potential of curdlan against Mtb and the underlying mechanism is largely unknown. We found that curdlan treatment enhanced the antigen presentation, pro-inflammatory cytokines, Mtb uptake and killing activity of macrophages. In vivo studies showed that curdlan therapy significantly reduced the Mtb burden in lung and spleen of mice. Administration of curdlan triggered the protective Th1 and Th17 immunity while boosting the central and effector memory response in Mtb infected mice. Curdlan mediated anti-Mtb activity is through signal transducer and activator of transcription-1 (STAT-1), which regulates nitric oxide (NO) production through inducible NO synthase (iNOS) induction; along with this activation of nuclear factor kappa B (NF-κB) was also evident in Mtb infected macrophages. Thus, we demonstrate that curdlan exerts effective anti-tuberculous activity anti-tuberculous activity. It can be used as a potential host-directed therapy against Mtb.

Constitutive STAT3 phosphorylation and IL-6/IL-10 co-expression are associated with impaired T-cell function in tuberculosis patients

T-cells critically contribute to protection against Mycobacterium tuberculosis infection, and impaired T-cell responses can lead to disease progression. Pro-inflammatory and immunosuppressive cytokines affect T-cells, and fine-tuned regulation of cytokine signaling via the Jak/STAT signaling pathways is crucial for appropriate T-cell function. Constitutive STAT3 phosphorylation as a consequence of aberrant cytokine signaling has been described to occur in pathognomonic T-cell responses in inflammatory and autoimmune diseases. We characterized blood samples from tuberculosis patients (n=28) and healthy contacts (n=28) from Ghana for M. tuberculosis-specific T-cell responses, constitutive cytokine production, and SOCS3 and pSTAT3 expression. Lentiviral modulation of primary CD4+ T-cells was performed to determine the effects of SOCS3 on T-cell functions. T-cells from tuberculosis patients expressed higher levels of IL-10 and IL-6 and lower levels of T helper type (TH)17 cytokines after M. tuberculosis-specific stimulation compared to healthy contacts. In addition, tuberculosis patients had higher IL-10 and IL-6 levels in the supernatants of non-stimulated immune cells and plasma samples compared to healthy contacts. Notably, aberrant cytokine expression was accompanied by high constitutive pSTAT3 levels and SOCS3 expression in T-cells. Multivariate analysis identified an IL-6/IL-10 co-expression-based principal component in tuberculosis patients that correlated with high pSTAT3 levels. SOCS3 contributed to a regulatory component, and tuberculosis patients with high SOCS3 expression showed decreased TH1 cytokine expression and impaired IL-2-induced STAT5 phosphorylation. SOCS3 over-expression in primary CD4+ T-cells confirmed the SOCS3 inhibitory function on IL-2-induced STAT5 phosphorylation. We conclude that constitutive pSTAT3 and high SOCS3 expression are influential factors that indicate impaired T-cell functions in tuberculosis patients.

Mycobacterium tuberculosis ESAT6 Drives the Activation and Maturation of Bone Marrow-Derived Dendritic Cells via TLR4-Mediated Signaling

6-kDa early secretory antigenic target (ESAT6), a virulent factor of Mycobacterium tuberculosis, is involved in immune regulation. However, the underlying mechanism behind the activation and maturation of dendritic cells (DCs) by ESAT6 remains unclear. In this study, we investigated the effect on TLRs signaling on the regulation of ESAT6-induced activation and maturation of DCs. ESAT6 induced production of IL-6, TNF-α, and IL-12p40 in bone marrow-derived dendritic cells (BMDCs) from wild-type and TLR2-deficient mice, with this induction abolished in TLR4-deficient cells. NF-κB is essential for the ESAT6-induced production of the cytokines in BMDCs. TLR4 was also required for ESAT6-induced activation of NF-κB and MAPKs in BMDCs. ESAT6 additionally upregulated the expression of surface molecules CD80, CD86, and MHC-II, and also promoted the ability of CD4⁺ T cells to secrete IFN-γ via the TLR4-dependent pathway. Our findings suggest that TLR4 is critical in the activation and maturation of DCs in response to ESAT6.

Host Directed Therapy for Chronic Tuberculosis via Intrapulmonary Delivery of Aerosolized Peptide Inhibitors Targeting the IL-10-STAT3 Pathway

Here we demonstrate that aerosols of host directed therapies [HDT] administered during a chronic Mycobacterium tuberculosis (Mtb) infection have bactericidal effect. The pulmonary bacterial load of C57BL/6 mice chronically infected with Mtb was reduced by 1.7 and 0.6 log₁₀CFU after two weeks of treatment via aerosol delivery with ST3-H2A2, [a selective peptide inhibitor of the STAT3 N-terminal domain] or IL10R1-7 [selective peptide inhibitor for the IL-10Ra] respectively and when compared to control mice treated with IL10R1-14 [peptide inhibitor used as negative control] or untreated mice infected with Mtb. Accordingly, when compared to control mice, the bactericidal capacity in mice was enhanced upon treatment with peptide inhibitors ST3-H2A2 and IL10R1-7 as evidenced by higher pulmonary activities of nitric oxide synthase, NADPH oxidase and lysozyme enzymes and decreased arginase enzyme activity. This therapy also modulated important checkpoints [Bcl2, Beclin-1, Atg 5, bax] in the apoptosis-autophagy pathways. Thus, even in the absence of antibiotics, targeting of the host pulmonary IL-10-STAT3 pathway can significantly reduce the Mtb bacilli load in the lungs, modulate the host own bactericidal capacity and apoptosis and autophagy pathways. Our approach here also allows targeting checkpoints of the lungs to determine their specific contribution in pulmonary immunity or pathogenesis.

PPE11 of Mycobacterium tuberculosis can alter host inflammatory response and trigger cell death

Tuberculosis (TB), which is caused by Mycobacterium tuberculosis (Mtb), remains a serious global health problem. The PE/PPE family, featuring unique sequences, structures and expression in Mtb, is reported to interfere with the macrophage response to the pathogen and facilitate its infection. PPE11 (Rv0453) existed in pathogenic mycobacteria and was persistently expressed in the infected guinea pig lungs. However, the role it played in the pathogenesis remains unclear. Here, to investigate the interaction and potential mechanism of PPE11 between pathogens and hosts, we heterologously expressed PPE11 in non-pathogenic, rapidly growing Mycobacterium smegmatis strains. We found that the overexpression of the cell wall-associated protein, PPE11, can improve the viability of bacteria in the presence of lysozyme, hydrogen peroxide and acid stress. Expression of PPE11 enhanced the early survival of M. smegmatis in macrophages and sustained a higher bacterial load in mouse tissues that showed exacerbated organ pathology. Macrophages infected with recombinant M. smegmatis produced significantly greater amounts of interleukin (IL)-1β, IL-6, tumour necrosis factor (TNF)-α and an early decrease in IL-10 along with higher levels of host cell death. Similar cytokines changes were observed in the sera of infected mice. Accordingly, PPE11 protein causes histopathological changes by disrupting the dynamic balance of the inflammatory factors and promoting host-cell death, indicating a potential role in the virulence of Mtb.

High Antigen Dose Is Detrimental to Post-Exposure Vaccine Protection against Tuberculosis

Mycobacterium tuberculosis (Mtb), the etiologic agent of tuberculosis (TB), causes 1.8M deaths annually. The current vaccine, BCG, has failed to eradicate TB leaving 25% of the world’s population with latent Mtb infection (LTBI), and 5–10% of these people will reactivate and develop active TB. An efficient therapeutic vaccine targeting LTBI could have an enormous impact on global TB incidence, and could be an important aid in fighting multidrug resistance, which is increasing globally. Here we show in a mouse model using the H56 (Ag85B-ESAT-6-Rv2660) TB vaccine candidate that post-exposure, but not preventive, vaccine protection requires low vaccine antigen doses for optimal protection. Loss of protection from high dose post-exposure vaccination was not associated with a loss of overall vaccine response magnitude, but rather with greater differentiation and lower functional avidity of vaccine-specific CD4 T cells. High vaccine antigen dose also led to a decreased ability of vaccine-specific CD4 T cells to home into the Mtb-infected lung parenchyma, a recently discovered important feature of T cell protection in mice. These results underscore the importance of T cell quality rather than magnitude in TB-vaccine protection, and the significant role that antigen dosing plays in vaccine-mediated protection.

The crucial roles of Th17-related cytokines/signal pathways in M. tuberculosis infection

Interleukin-17 (IL-17), IL-21, IL-22 and IL-23 can be grouped as T helper 17 (Th17)-related cytokines because they are either produced by Th17/Th22 cells or involved in their development. Here, we review Th17-related cytokines/Th17-like cells, networks/signals and their roles in immune responses or immunity against Mycobacterium tuberculosis (Mtb) infection. Published studies suggest that Th17-related cytokine pathways may be manipulated by Mtb microorganisms for their survival benefits in primary tuberculosis (TB). In addition, there is evidence that immune responses of the signal transducer and activator of transcription 3 (STAT3) signal pathway and Th17-like T-cell subsets are dysregulated or destroyed in patients with TB. Furthermore, Mtb infection can impact upstream cytokines in the STAT3 pathway of Th17-like responses. Based on these findings, we discuss the need for future studies and the rationale for targeting Th17-related cytokines/signals as a potential adjunctive treatment.

Oxidative Stress Markers in Tuberculosis and HIV/TB Co-Infection

INTRODUCTION

Dysfunction of redox homeostasis has been implicated in many pathological conditions. An imbalance of pro- and anti-oxidants have been observed in Tuberculosis (TB) and its co-morbidities especially HIV/AIDS. The pro inflammatory milieu in either condition aggravates the physiological balance of the redox mechanisms. The present study therefore focuses on assessing the redox status of patients suffering from TB and HIV-TB co-infection.

AIM

To assess the oxidative stress markers in the HIV-TB and TB study cohort.

MATERIALS AND METHODS

The current prospective study was conducted in Haffkine Institute, Parel, Maharashtra, India, during January 2013 to December 2015. Blood samples from 50 patients each suffering from active TB and HIV-TB co-infection were collected from Seth G.S.Medical College and KEM Hospital Mumbai and Group of Tuberculosis Hospital, Sewree Mumbai. Samples were processed and the experiments were carried out at the Department of Biochemistry, Haffkine Institute. Samples from 50 healthy volunteers were used as controls. Serum was assessed for pro-oxidant markers such as Nitric Oxide (NO), Thiobarbituric Acid Reactive Species (TBARS), C-Reactive Protein (CRP), superoxide anion. Antioxidant markers such as catalase and Superoxide Dismutase (SOD) were assessed. Total serum protein, was also assessed.

RESULTS

Among the pro-oxidants, serum NO levels were decreased in TB group while no change was seen in HIV-TB group. TBARS and CRP levels showed significant increase in both groups; superoxide anion increased significantly in HIV-TB group. Catalase levels showed decreased activities in TB group. SOD activity significantly increased in HIV-TB but not in TB group. The total serum proteins were significantly increased in HIV-TB and TB groups. The values of Control cohort were with the normal reference ranges.

CONCLUSION

In the present study, we found the presence of oxidative stress to be profound in the TB and HIV-TB co-infection population.