Berberine governs NOTCH3/AKT signaling to enrich lung-resident memory T cells during tuberculosis

Effect of urolithin A on intracellular survival of Mycobacterium tuberculosis by regulating AKT-FOXO1-mediated autophagy

Tuberculosis (TB), resulting from Mycobacterium tuberculosis (Mtb), is one of the leading causes of morbidity and mortality in humans worldwide. Host-directed therapy (HDT) is a novel approach for treating TB, particularly those with drug resistance. Urolithin A (UroA) produced through bioconversion of plant-derived ellagic acid by gut microbes has been proven to have multiple beneficial effects in a variety of diseases without showing undesired adverse reactions. However, whether UroA has antimycobacterial effect and the underlying mechanism has not yet been reported. Here, we found that UroA significantly inhibited Mtb growth within both macrophages and mice. Moreover, UroA promoted the activation of autophagy in Mtb-infected macrophages via the protein kinase B-Forkhead box protein O1 signaling pathway, which contributed to the antimycobacterial effect of UroA. Additionally, UroA suppressed the survival of clinically isoniazid (INH)-resistant Mtb (C2) within macrophages, and the combination of UroA and INH synergistically enhanced host elimination of Mtb H37Rv. Therefore, UroA may be utilized as a potential candidate for HDT and as an adjunctive therapy with first-line anti-TB drugs.IMPORTANCEHost-directed therapy (HDT) is a novel approach for treating tuberculosis (TB), particularly those with drug resistance. Urolithin A (UroA) produced through bioconversion of plant-derived ellagic acid by gut microbes has been proven to have multiple beneficial effects in a variety of diseases without showing undesired adverse reactions. We found that UroA significantly inhibited Mycobacterium tuberculosis (Mtb) growth within macrophages. Moreover, UroA suppressed the survival of clinically isoniazid (INH)-resistant Mtb (C2) within macrophages, and the combination of UroA and INH synergistically enhanced host elimination of Mtb H37Rv. Therefore, UroA may be utilized as a potential candidate for HDT and as an adjunctive therapy with first-line anti-TB drugs.

Tissue-resident immune cells: from defining characteristics to roles in diseases

Tissue-resident immune cells (TRICs) are a highly heterogeneous and plastic subpopulation of immune cells that reside in lymphoid or peripheral tissues without recirculation. These cells are endowed with notably distinct capabilities, setting them apart from their circulating leukocyte counterparts. Many studies demonstrate their complex roles in both health and disease, involving the regulation of homeostasis, protection, and destruction. The advancement of tissue-resolution technologies, such as single-cell sequencing and spatiotemporal omics, provides deeper insights into the cell morphology, characteristic markers, and dynamic transcriptional profiles of TRICs. Currently, the reported TRIC population includes tissue-resident T cells, tissue-resident memory B (BRM) cells, tissue-resident innate lymphocytes, tissue-resident macrophages, tissue-resident neutrophils (TRNs), and tissue-resident mast cells, but unignorably the existence of TRNs is controversial. Previous studies focus on one of them in specific tissues or diseases, however, the origins, developmental trajectories, and intercellular cross-talks of every TRIC type are not fully summarized. In addition, a systemic overview of TRICs in disease progression and the development of parallel therapeutic strategies is lacking. Here, we describe the development and function characteristics of all TRIC types and their major roles in health and diseases. We shed light on how to harness TRICs to offer new therapeutic targets and present burning questions in this field.

Repurposed Drugs and Plant-Derived Natural Products as Potential Host-Directed Therapeutic Candidates for Tuberculosis

Tuberculosis (TB) is one of the leading causes of death due to infectious disease. It is a treatable disease; however, conventional treatment requires a lengthy treatment regimen with severe side effects, resulting in poor compliance among TB patients. Intermittent drug use, the non-compliance of patients, and prescription errors, among other factors, have led to the emergence of multidrug-resistant TB, while the mismanagement of multidrug-resistant TB (MDR-TB) has eventually led to the development of extensively drug-resistant tuberculosis (XDR-TB). Thus, there is an urgent need for new drug development, but due to the enormous expenses and time required (up to 20 years) for new drug research and development, new therapeutic approaches to TB are required. Host-directed therapies (HDT) could be a most attractive strategy, as they target the host defense processes instead of the microbe and thereby may prevent the alarming rise of MDR- and XDR-TB. This paper reviews the progress in HDT for the treatment of TB using repurposed drugs which have been investigated in clinical trials (completed or ongoing) and plant-derived natural products that are in clinical or preclinical trial stages. Additionally, this review describes the existing challenges to the development and future research directions in the implementation of HDT.

Berberine Protects against Hepatocellular Carcinoma Progression by Regulating Intrahepatic T Cell Heterogeneity

Accumulating evidence suggests that berberine (BBR) exhibits anti-cancer effects in hepatocellular carcinoma (HCC). However, the mechanisms by which BBR regulates the immunological microenvironment in HCC has not been fully elucidated. In this study, a mouse model of orthotopic HCC is established and treated with varying doses of BBR. BBR showed effectiveness in reducing tumor burden in mice with HCC. Cytometry by time-of-flight depicted the alterations in the tumor immune landscape following BBR treatment, revealing the enhancement in the T lymphocytes effector function. In particular, BBR decreased the proportion of TCRbhiPD-1hiCD69+CD27+ effector CD8+ T lymphocytes and increased the proportion of Ly6ChiTCRb+CD69+CD27+CD62L+ central memory CD8+ T lymphocytes. Single-cell RNA sequencing further elucidates the effects of BBR on transcriptional profiles of liver immune cells and confirms the phenotypical heterogeneity of T lymphocytes in HCC immune microenvironment. Additionally, it is found that BBR potentially regulated the antitumor immunity in HCC by modulating the receptor-ligand interaction among immune cells mediated by cytokines. In summary, the findings improve the understanding of BBR's impact on protecting against HCC, emphasizing BBR's role in regulating intrahepatic T cell heterogeneity. BBR has the potential to be a promising therapeutic strategy to hinder the advancement of HCC.

Depletion of essential mycobacterial gene glmM reduces pathogen survival and induces host-protective immune responses against tuberculosis

The limitations of TB treatment are the long duration and immune-dampening effects of anti-tuberculosis therapy. The Cell wall plays a crucial role in survival and virulence; hence, enzymes involved in its biosynthesis are good therapeutic targets. Here, we identify Mycobacterium tuberculosis (Mtb) GlmM, (GlmMMtb) engaged in the UDP-GlcNAc synthesis pathway as an essential enzyme. We generated a conditional knockdown strain, Rv-glmMkD using the CRISPR interference-mediated gene silencing approach. Depletion of GlmMMtb affects the morphology and thickness of the cell wall. The Rv-glmMkD strain attenuated Mtb survival in vitro, in the host macrophages (ex vivo), and in a murine mice infection model (in vivo). Results suggest that the depletion of GlmMMtb induces M1 macrophage polarization, prompting a pro-inflammatory cytokine response, apparent from the upregulation of activation markers, including IFNɣ and IL-17 that resists the growth of Mtb. These observations provide a rationale for exploring GlmMMtb as a potential therapeutic target.

Immunoinhibitory effects of anti-tuberculosis therapy induce the host vulnerability to tuberculosis recurrence

The host immune responses play a pivotal role in the establishment of long-term memory responses, which effectively aids in infection clearance. However, the prevailing anti-tuberculosis therapy, while aiming to combat tuberculosis (TB), also debilitates innate and adaptive immune components of the host. In this study, we explored how the front-line anti-TB drugs impact the host immune cells by modulating multiple signaling pathways and subsequently leading to disease relapse. Administration of these drugs led to a reduction in innate immune activation and also the cytokines required to trigger protective T cell responses. Moreover, these drugs led to activation-induced cell death in the mycobacterial-specific T cell leading to a reduced killing capacity. Furthermore, these drugs stalled the T cell differentiation into memory subsets by modulating the activation of STAT3, STAT4, FOXO1, and NFκB transcription factors and hampering the Th1 and Th17-mediated long-term host protective memory responses. These findings suggest the urgent need to augment directly observed treatment, short-course (DOTS) therapy with immunomodulatory agents to mitigate the adverse effects linked to the treatment.IMPORTANCEAs a central component of TB eradication initiatives, directly observed treatment, short-course (DOTS) therapy imparts immune-dampening effects during the course of treatment. This approach undermines the host immune system by delaying the activation process and lowering the immune response. In our investigation, we have unveiled the impact of DOTS on specific immune cell populations. Notably, the signaling pathways involving STAT3 and STAT4 critical for memory responses and NFκβ associated with pro-inflammation were substantially declined due to the therapy. Consequently, these drugs exhibit limited effectiveness in preventing recurrence of the disease. These observations highlight the imperative integration of immunomodulators to manage TB infection.

Bergenin potentiates BCG efficacy by enriching mycobacteria-specific adaptive memory responses via the Akt-Foxo-Stat4 axis

The extensive inability of the BCG vaccine to produce long-term immune protection has not only accelerated the disease burden but also progressed towards the onset of drug resistance. In our previous study, we have reported the promising effects of Bergenin (Berg) in imparting significant protection as an adjunct immunomodulator against tuberculosis (TB). In congruence with our investigations, we delineated the impact of Berg on T cells, wherein it enhanced adaptive memory responses by modulating key transcription factors, STAT4 and Akt. We translated this finding into the vaccine model of TB and observed a notable reduction in the burden of Mycobacterium tuberculosis (M.tb) in BCG-Berg co-immunized mice as compared to BCG vaccination. Moreover, Berg, along with BCG, also aided in a heightened proinflammatory response milieu that corroborates the host protective immune response against TB. Furthermore, this response aligns with the escalated central and resident memory responses by modulating the Akt-Foxo-Stat4 axis, which plays a crucial role in enhancing the vaccine efficacy of BCG. These findings showcase the utilization of immunomodulator Berg as an immunoprophylactic agent to upgrade immunological memory, making it a more effective defender against TB.

Systemic Pharmacotherapeutic Treatment of the ACTA1-MCM/FLExDUX4 Preclinical Mouse Model of FSHD

Aberrant expression of the double homeobox 4 (DUX4) gene in skeletal muscle predominantly drives the pathogenesis of facioscapulohumeral muscular dystrophy (FSHD). We recently demonstrated that berberine, an herbal extract known for its ability to stabilize guanine-quadruplex structures, effectively downregulates DUX4 expression in FSHD patient-derived myoblasts and in mice overexpressing exogenous DUX4 after viral vector-based treatment. Here, we sought to confirm berberine's inhibitory efficacy on DUX4 in the widely used FSHD-like transgenic mouse model, ACTA1-MCM/FLExDUX4, where DUX4 is induced at pathogenic levels using tamoxifen. Animals repeatedly treated with berberine via intraperitoneal injections for 4 weeks exhibited significant reductions in both mRNA and protein levels of DUX4, and in mRNA expression of murine DUX4-related genes. This inhibition translated into improved forelimb muscle strength and positive alterations in important FSHD-relevant cellular pathways, although its impact on muscle mass and histopathology was less pronounced. Collectively, our data confirm the efficacy of berberine in downregulating DUX4 expression in the most relevant FSHD mouse model. However, further optimization of dosing regimens and new studies to enhance the bioavailability of berberine in skeletal muscle are warranted to fully leverage its therapeutic potential for FSHD treatment.

The advances in adjuvant therapy for tuberculosis with immunoregulatory compounds

Tuberculosis (TB) is a chronic bacterial disease, as well as a complex immune disease. The occurrence, development, and prognosis of TB are not only related to the pathogenicity of Mycobacterium tuberculosis (Mtb), but also related to the patient's own immune state. The research and development of immunotherapy drugs can effectively regulate the body's anti-TB immune responses, inhibit or eliminate Mtb, alleviate pathological damage, and facilitate rehabilitation. This paper reviews the research progress of immunotherapeutic compounds for TB, including immunoregulatory compounds and repurposing drugs, and points out the existing problems and future research directions, which lays the foundation for studying new agents for host-directed therapies of TB.

Notch3 as a novel therapeutic target for the treatment of ADPKD by regulating cell proliferation and renal cyst development

Autosomal dominant polycystic kidney disease (ADPKD) is a common monogenic kidney disease. Emerging research indicates that the Notch signaling pathway plays an indispensable role in the pathogenesis of numerous kidney diseases, including ADPKD. Herein, we identified that Notch3 but not other Notch receptors was overexpressed in renal tissues from mice with ADPKD and ADPKD patients. Inhibiting Notch3 with γ-secretase inhibitors, which block a proteolytic cleavage required for Notch3 activation, or shRNA knockdown of Notch3 significantly delayed renal cyst growth in vitro and in vivo. Subsequent mechanistic study elucidated that the cleaved intracellular domain of Notch3 (N3ICD) and Hes1 could bind to the PTEN promoter, leading to transcriptional inhibition of PTEN. This further activated the downstream PI3K-AKT-mTOR pathway and promoted renal epithelial cell proliferation. Overall, Notch3 was identified as a novel contributor to renal epithelial cell proliferation and cystogenesis in ADPKD. We envision that Notch3 represents a promising target for ADPKD treatment.

Single-cell transcriptome reveals highly complement activated microglia cells in association with pediatric tuberculous meningitis

Background

Tuberculous meningitis (TBM) is a devastating form of tuberculosis (TB) causing high mortality and disability. TBM arises due to immune dysregulation, but the underlying immune mechanisms are unclear.

Methods

We performed single-cell RNA sequencing on peripheral blood mononuclear cells (PBMCs) and cerebrospinal fluid (CSF) cells isolated from children (n=6) with TBM using 10 xGenomics platform. We used unsupervised clustering of cells and cluster visualization based on the gene expression profiles, and validated the protein and cytokines by ELISA analysis.

Results

We revealed for the first time 33 monocyte populations across the CSF cells and PBMCs of children with TBM. Within these populations, we saw that CD4_C04 cells with Th17 and Th1 phenotypes and Macro_C01 cells with a microglia phenotype, were enriched in the CSF. Lineage tracking analysis of monocyte populations revealed myeloid cell populations, as well as subsets of CD4 and CD8 T-cell populations with distinct effector functions. Importantly, we discovered that complement-activated microglial Macro_C01 cells are associated with a neuroinflammatory response that leads to persistent meningitis. Consistently, we saw an increase in complement protein (C1Q), inflammatory markers (CRP) and inflammatory factor (TNF-α and IL-6) in CSF cells but not blood. Finally, we inferred that Macro_C01 cells recruit CD4_C04 cells through CXCL16/CXCR6.

Discussion

We proposed that the microglial Macro_C01 subset activates complement and interacts with the CD4_C04 cell subset to amplify inflammatory signals, which could potentially contribute to augment inflammatory signals, resulting in hyperinflammation and an immune response elicited by Mtb-infected tissues.

Unravelling the potential of Triflusal as an anti-TB repurposed drug by targeting replication protein DciA

The increasing prevalence of drug-resistant Tuberculosis (TB) is imposing extreme difficulties in controlling the TB infection rate globally, making treatment critically challenging. To combat the prevailing situation, it is crucial to explore new anti-TB drugs with a novel mechanism of action and high efficacy. The Mycobacterium tuberculosis (M.tb)DciA is an essential protein involved in bacterial replication and regulates its growth. DciA interacts with DNA and provides critical help in binding other replication machinery proteins to the DNA. Moreover, the lack of any structural homology of M.tb DciA with human proteins makes it an appropriate target for drug development. In this study, FDA-approved drugs were virtually screened against M.tb DciA to identify potential inhibitors. Four drugs namely Lanreotide, Risedronate, Triflusal, and Zoledronic acid showed higher molecular docking scores. Further, molecular dynamics simulations analysis of DciA-drugs complexes reported stable interaction, more compactness, and reduced atomic motion. The anti-TB activity of drugs was further evaluated under in vitro and ex vivo conditions where Triflusal was observed to have the best possible activity with the MIC of 25 μg/ml. Our findings present novel DciA inhibitors and anti-TB activity of Triflusal. Further investigations on the use of Triflusal may lead to the discovery of a new anti-TB drug.

Antitubercular drugs: possible role of natural products acting as antituberculosis medication in overcoming drug resistance and drug-induced hepatotoxicity

Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium which causes tuberculosis (TB). TB control programmes are facing threats from drug resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains need longer and more expensive treatment with many medications resulting in more adverse effects and decreased chances of treatment outcomes. The World Health Organization (WHO) has emphasised the development of not just new individual anti-TB drugs, but also novel medication regimens as an alternative treatment option for the drug-resistant Mtb strains. Many plants, as well as marine creatures (sponge; Haliclona sp.) and fungi, have been continuously used to treat TB in various traditional treatment systems around the world, providing an almost limitless supply of active components. Natural products, in addition to their anti-mycobacterial action, can be used as adjuvant therapy to increase the efficacy of conventional anti-mycobacterial medications, reduce their side effects, and reverse MDR Mtb strain due to Mycobacterium's genetic flexibility and environmental adaptation. Several natural compounds such as quercetin, ursolic acid, berberine, thymoquinone, curcumin, phloretin, and propolis have shown potential anti-mycobacterial efficacy and are still being explored in preclinical and clinical investigations for confirmation of their efficacy and safety as anti-TB medication. However, more high-level randomized clinical trials are desperately required. The current review provides an overview of drug-resistant TB along with the latest anti-TB medications, drug-induced hepatotoxicity and oxidative stress. Further, the role and mechanisms of action of first and second-line anti-TB drugs and new drugs have been highlighted. Finally, the role of natural compounds as anti-TB medication and hepatoprotectants have been described and their mechanisms discussed.

Natural products in anti-tuberculosis host-directed therapy

Given that the disease progression of tuberculosis (TB) is primarily related to the host's immune status, it has been gradually realized that chemotherapy that targets the bacteria may never, on its own, wholly eradicate Mycobacterium tuberculosis, the causative agent of TB. The concept of host-directed therapy (HDT) with immune adjuvants has emerged. HDT could potentially interfere with infection and colonization by the pathogens, enhance the protective immune responses of hosts, suppress the overwhelming inflammatory responses, and help to attain a state of homeostasis that favors treatment efficacy. However, the HDT drugs currently being assessed in combination with anti-TB chemotherapy still face the dilemmas arising from side effects and high costs. Natural products are well suited to compensate for these shortcomings by having gentle modulatory effects on the host immune responses with less immunopathological damage at a lower cost. In this review, we first summarize the profiles of anti-TB immunology and the characteristics of HDT. Then, we focus on the rationale and challenges of developing and implementing natural products-based HDT. A succinct report of the medications currently being evaluated in clinical trials and preclinical studies is provided. This review aims to promote target-based screening and accelerate novel TB drug discovery.

The uncharted territory of host-pathogen interaction in tuberculosis

Mycobacterium tuberculosis (M.tb) effectively manipulates the host processes to establish the deadly respiratory disease, Tuberculosis (TB). M.tb has developed key mechanisms to disrupt the host cell health to combat immune responses and replicate efficaciously. M.tb antigens such as ESAT-6, 19kDa lipoprotein, Hip1, and Hsp70 destroy the integrity of cell organelles (Mitochondria, Endoplasmic Reticulum, Nucleus, Phagosomes) or delay innate/adaptive cell responses. This is followed by the induction of cellular stress responses in the host. Such cells can either undergo various cell death processes such as apoptosis or necrosis, or mount effective immune responses to clear the invading pathogen. Further, to combat the infection progression, the host secretes extracellular vesicles such as exosomes to initiate immune signaling. The exosomes can contain M.tb as well as host cell-derived peptides that can act as a double-edged sword in the immune signaling event. The host-symbiont microbiota produces various metabolites that are beneficial for maintaining healthy tissue microenvironment. In juxtaposition to the above-mentioned mechanisms, M.tb dysregulates the gut and respiratory microbiome to support its replication and dissemination process. The above-mentioned interconnected host cellular processes of Immunometabolism, Cellular stress, Host Microbiome, and Extracellular vesicles are less explored in the realm of exploration of novel Host-directed therapies for TB. Therefore, this review highlights the intertwined host cellular processes to control M.tb survival and showcases the important factors that can be targeted for designing efficacious therapy.

Cotreatment With Clofazimine and Rapamycin Eliminates Drug-Resistant Tuberculosis by Inducing Polyfunctional Central Memory T-Cell Responses

Mycobacterium tuberculosis, the causative agent of tuberculosis, is acquiring drug resistance at a faster rate than the discovery of new antibiotics. Therefore, alternate therapies that can limit the drug resistance and disease recurrence are urgently needed. Emerging evidence indicates that combined treatment with antibiotics and an immunomodulator provides superior treatment efficacy. Clofazimine (CFZ) enhances the generation of T central memory (TCM) cells by blocking the Kv1.3+ potassium channels. Rapamycin (RAPA) facilitates M. tuberculosis clearance by inducing autophagy. In this study, we observed that cotreatment with CFZ and RAPA potently eliminates both multiple and extensively drug-resistant (MDR and XDR) clinical isolates of M. tuberculosis in a mouse model by inducing robust T-cell memory and polyfunctional TCM responses. Furthermore, cotreatment reduces the expression of latency-associated genes of M. tuberculosis in human macrophages. Therefore, CFZ and RAPA cotherapy holds promise for treating patients infected with MDR and XDR strains of M. tuberculosis.

Biapenem, a Carbapenem Antibiotic, Elicits Mycobacteria Specific Immune Responses and Reduces the Recurrence of Tuberculosis

Tuberculosis (TB) still tops the list of global health burdens even after COVID-19. However, it will sooner transcend the current pandemic due to the prevailing risk of reactivation of latent TB in immunocompromised individuals. The indiscriminate misuse and overuse of antibiotics have resulted in the emergence of deadly drug-resistant variants of Mycobacterium tuberculosis (M.tb). This study aims to characterize the functionality of the carbapenem antibiotic-Biapenem (BPM) in generating long-lasting immunity against TB. BPM treatment significantly boosted the activation status of the innate immune arm-macrophages by augmenting p38 signaling. Macrophages further primed and activated the adaptive immune cells CD4+ and CD8+ T-cells in the lung and spleen of the infected mice model. Furthermore, BPM treatment significantly amplified the polarization of T lymphocytes toward inflammatory subsets, such as Th1 and Th17. The treatment also helped generate a long-lived central memory T-cell subset. The generation of central memory T lymphocyte subset upon BPM treatment in the murine model led to a significant curtailing in the recurrence of TB due to reactivation and reinfection. These results suggest the potentiality of BPM as a potent adjunct immunomodulator to improve host defense against M.tb by enriching long-term protective memory cells. IMPORTANCE Tuberculosis (TB) caused by Mycobacterium tuberculosis (M.tb) tops the list of infectious killers around the globe. The emergence of drug-resistant variants of M.tb has been a major hindrance toward realizing the "END TB" goal. Drug resistance has amplified the global burden toward the quest for novel drug molecules targeting M.tb. Host-directed therapy (HDT) offers a lucrative alternative to tackle emerging drug resistance and disease relapse by strengthening the host's immunity. Through our present study, we have tried to characterize the functionality of the carbapenem antibiotic-Biapenem (BPM). BPM treatment significantly augmented long-lasting immunity against TB by boosting the innate and adaptive immune arms. The generation of long-lived central memory T lymphocyte subset significantly improved the disease outcome and provided sterilizing immunity in the murine model of TB. The present investigation's encouraging results have helped us depict BPM as a potent adjunct immunomodulator for treating TB.