Tumor necrosis factor signaling mediates resistance to mycobacteria by inhibiting bacterial growth and macrophage death

Infection and infestation-related adverse events of biologics in psoriasis: insights from the Food and Drug Administration Adverse Event Reporting System (FAERS)

OBJECTIVE

The study aims to thoroughly assess the adverse events related to infections and infestations associated with biological agents used for psoriasis using the U.S. Food and Drug Administration's Adverse Event Reporting System (FAERS) database.

METHODS

We analyzed FAERS data from the first quarter of 2004 to the fourth quarter of 2023. The study included TNF-α inhibitors (etanercept, infliximab, adalimumab), IL-12/23 inhibitors (ustekinumab), IL-23p19 inhibitors (guselkumab), and IL-17 inhibitors (secukinumab, ixekizumab). We used disproportionality analysis and Bayesian methods to quantify the related adverse event (AE) signals.

RESULTS

Most AEs related to infections and infestations are already listed on the drug packaging labels. Notably, TNF-α inhibitors are associated with a significantly higher incidence of tuberculosis-related diseases compared to other biological agents. In contrast, IL-17 inhibitors show a greater variety and number of fungal infection-related AEs than their counterparts. Furthermore, our study has identified new potential AEs that require the attention of clinicians.

CONCLUSION

In clinical practice, it is advisable to monitor the risks of infections and infestations in patients receiving biological agents for psoriasis to enable early detection and intervention. Our findings highlight the need for further epidemiological investigations to establish causality and guide clinical practice in managing these risks effectively.

Mycobacterium tuberculosis Utilizes Serine/Threonine Kinase PknF to Evade NLRP3 Inflammasome-driven Caspase-1 and RIPK3/Caspase-8 Activation in Murine Dendritic Cells

Dendritic cells (DCs) are crucial for initiating the acquired immune response to infectious diseases such as tuberculosis. Mycobacterium tuberculosis has evolved strategies to inhibit activation of the NLRP3 inflammasome in macrophages via its serine/threonine protein kinase, protein kinase F (PknF). It is not known whether this pathway is conserved in DCs. In this study, we show that the pknF deletion mutant of M. tuberculosis (MtbΔpknF) compared with wild-type M. tuberculosis-infected cells induces increased production of IL-1β and increased pyroptosis in murine bone marrow-derived DCs (BMDCs). As shown for murine macrophages, the enhanced production of IL-1β postinfection of BMDCs with MtbΔpknF is dependent on NLRP3, ASC, and caspase-1/11. In contrast to macrophages, we show that MtbΔpknF mediates RIPK3/caspase-8-dependent IL-1β production in BMDCs. Consistently, infection with MtbΔpknF results in increased activation of caspase-1 and caspase-8 in BMDCs. When compared with M. tuberculosis-infected cells, the IL-6 production by MtbΔpknF-infected cells was unchanged, indicating that the mutant does not affect the priming phase of inflammasome activation. In contrast, the activation phase was impacted because the MtbΔpknF-induced inflammasome activation in BMDCs depended on potassium efflux, chloride efflux, reactive oxygen species generation, and calcium influx. In conclusion, PknF is important for M. tuberculosis to evade NLRP3 inflammasome-mediated activation of caspase-1 and RIPK3/caspase-8 pathways in BMDCs.

Identification of immune-associated genes involved in latent Mycobacterium marinum infection

Tuberculosis (TB) is a high mortality infectious disease caused by Mycobacterium tuberculosis (Mtb), and often develops into latent infection. About 5～10% of latent infections turn into active tuberculosis when the host immune system becomes deficient. Therefore, exploring the latent infection mechanism of Mtb is pivotal for the prevention and treatment of tuberculosis. We first established the zebrafish latent infection model and the chronic infection model utilizing Mycobacterium marinum, which has the highly similar gene background to Mtb. Using the latent infection model, we characterized the gene expression profiles and found 462 genes expressed differentially in the latent period and chronic tuberculosis infection. These differentially expressed genes are involved in various biological processes including transcription, transcriptional regulation, organism development, and immune responses. Among them, nineteen immune-related genes were found to express differentially in the latent period. By analyzing immune related protein network, the genes in the center of the network, including Nos2b, TNFα, IL1, TNFβ, TLR1, TLR2, and TLR4b, displayed significant deferential expression in latent infection and chronic infection period of zebrafish, suggesting that these genes might play an important role in controlling latent infection of Mtb. Identifying immune biomarker related to the status of tuberculosis latent infection might lead to novel strategy for diagnosis and treatment.

Modeling nontuberculous mycobacterial infections in zebrafish

The incidence of infections due to nontuberculous mycobacteria (NTM) has increased rapidly in recent years, surpassing tuberculosis in developed countries. Due to inherent antimicrobial resistance, NTM infections are particularly difficult to treat with low cure rates. There is an urgent need to understand NTM pathogenesis and to develop novel therapeutic approaches for the treatment of NTM diseases. Zebrafish have emerged as an excellent animal model due to genetic amenability and optical transparency during embryonic development, allowing spatiotemporal visualization of host-pathogen interactions. Furthermore, adult zebrafish possess fully functional innate and adaptive immunity and recapitulate important pathophysiological hallmarks of mycobacterial infection. Here, we report recent breakthroughs in understanding the hallmarks of NTM infections using the zebrafish model.

Humoral pathways of innate immune regulation in granuloma formation

The humoral arm of mammalian innate immunity regulates several molecular mechanisms involved in resistance to pathogens, inflammation, and tissue repair. Recent studies highlight the crucial role played by humoral mediators in granulomatous inflammation. However the molecular mechanisms linking the function of these soluble molecules to the initiation and maintenance of granulomas remain elusive. We propose that humoral innate immunity coordinates fundamental physiological processes in macrophages which, in turn, initiate activation and transformation events that enable granuloma formation. We discuss the involvement of humoral mediators in processes such as immune activation, phagocytosis, metabolism, and tissue remodeling, and how these can dictate macrophage functionality during granuloma formation. These advances present opportunities for discovering novel disease factors and developing targeted, more effective treatments for granulomatous diseases.

3D Hydrogel Culture System Recapitulates Key Tuberculosis Phenotypes and Demonstrates Pyrazinamide Efficacy

The mortality caused by tuberculosis (TB) infections is a global concern, and there is a need to improve understanding of the disease. Current in vitro infection models to study the disease have limitations such as short investigation durations and divergent transcriptional signatures. This study aims to overcome these limitations by developing a 3D collagen culture system that mimics the biomechanical and extracellular matrix (ECM) of lung microenvironment (collagen fibers, stiffness comparable to in vivo conditions) as the infection primarily manifests in the lungs. The system incorporates Mycobacterium tuberculosis (Mtb) infected human THP-1 or primary monocytes/macrophages. Dual RNA sequencing reveals higher mammalian gene expression similarity with patient samples than 2D macrophage infections. Similarly, bacterial gene expression more accurately recapitulates in vivo gene expression patterns compared to bacteria in 2D infection models. Key phenotypes observed in humans, such as foamy macrophages and mycobacterial cords, are reproduced in the model. This biomaterial system overcomes challenges associated with traditional platforms by modulating immune cells and closely mimicking in vivo infection conditions, including showing efficacy with clinically relevant concentrations of anti-TB drug pyrazinamide, not seen in any other in vitro infection model, making it reliable and readily adoptable for tuberculosis studies and drug screening.

Comparative transcriptomics reveals common and strain-specific responses of human macrophages to infection with Mycobacterium tuberculosis and Mycobacterium bovis BCG

Mycobacterium tuberculosis (MTB) and Mycobacterium bovis (M. bovis) are closely related pathogenic mycobacteria known to cause chronic pulmonary infections in both humans and animals. Despite sharing nearly identical genomes and virulence factors, these two bacteria display variations in host tropism, epidemiology, and clinical presentations. M. bovis Bacillus Calmette-Guérin (BCG) is an attenuated strain of M. bovis commonly utilized as a vaccine for tuberculosis (TB). Nevertheless, the molecular underpinnings of these distinctions and the intricacies of host-pathogen interactions remain areas of ongoing research. In this study, a comparative transcriptomic analysis was conducted on human leukemia macrophages (THP-1) infected with either MTB H37Rv or M. bovis BCG (Tokyo strain) to elucidate common and strain-specific responses at the transcriptional level. RNA sequencing was utilized to characterize the transcriptomes of human primary macrophages infected with MTB or BCG at 6 and 24 h post-infection. The findings indicate that both MTB and BCG induce substantial and dynamic alterations in the transcriptomes of THP-1, with a notable overlap in the quantity and extent of differentially expressed genes (DEGs). Moreover, gene ontology (GO) enrichment analysis unveiled shared pathways related to immune response, cytokine signaling, and apoptosis. The immune response of macrophages to bacterial infections at 6 h exhibited significantly greater intensity compared to that at 24 h. Furthermore, distinct gene sets displaying notable variances between MTB and BCG infections were identified. The profound impact of MTB infection on macrophage gene expression, particularly within the initial 6 h, was evident. Additionally, downregulation of pathways such as Focal adhesion, Rap1 signaling pathway, and Regulation of actin cytoskeleton was observed. The pathways associated with inflammation reactions and cell apoptosis exhibited significant differences, with BCG triggering macrophage apoptosis and MTB enhancing the survival of intracellular bacteria. Our findings reveal that MTB and BCG provoke similar yet distinct transcriptional responses in human macrophages, indicating variations in their pathogenesis and ability to adapt to host environments. These results offer novel insights into the molecular mechanisms governing host-pathogen interactions and may contribute to a deeper understanding of TB pathogenesis.

Interaction between air pollutants and meteorological factors on pulmonary tuberculosis in northwest China: A case study of eight districts in Urumqi

Meteorological factors and air pollutants are associated with the spread of pulmonary tuberculosis (PTB), but few studies have examined the effects of their interactions on PTB. Therefore, this study investigated the impact of meteorological factors and air pollutants and their interactions on the risk of PTB in Urumqi, a city with a high prevalence of PTB and a high level of air pollution. The number of new PTB cases in eight districts of Urumqi from 2014 to 2019 was collected, along with data on meteorological factors and air pollutants for the same period. A generalized additive model was applied to explore the effects of meteorological factors and air pollutants and their interactions on the risk of PTB incidence. Segmented linear regression was used to estimate the nonlinear characteristics of the impact of meteorological factors on PTB. During 2014-2019, a total of 14,402 new cases of PTB were reported in eight districts, with March to May being the months of high PTB incidence. The exposure-response curves for temperature (Temp), relative humidity (RH), wind speed (WS), air pressure (AP), and diurnal temperature difference (DTR) were generally inverted "U" shaped, with the corresponding threshold values of - 5.411 °C, 52.118%, 3.513 m/s, 1021.625 hPa, and 8.161 °C, respectively. The effects of air pollutants on PTB were linear and lagged. All air pollutants were positively associated with PTB, except for O3, which was not associated with PTB, and the ER values for the effects on PTB were as follows: 0.931 (0.255, 1.612) for PM2.5, 1.028 (0.301, 1.760) for PM10, 5.061 (0.387, 9.952) for SO2, 2.830 (0.512, 5.200) for NO2, and 5.789 (1.508, 10.251) for CO. Meteorological factors and air pollutants have an interactive effect on PTB. The risk of PTB incidence was higher when in high Temp-high air pollutant, high RH-high air pollutant, high WS-high air pollutant, lowAP-high air pollutant, and high DTR-high air pollutant. In conclusion, both meteorological and pollutant factors had an influence on PTB, and the influence on PTB may have an interaction.

IFN-γ enhances protective efficacy against Nocardia seriolae infection in largemouth bass (Micropterus salmoides)

Introduction

Nocardia seriolae adversely impacts a diverse range of fish species, exhibiting significant pathogenic characteristics that substantially impede the progress of aquaculture. N. seriolae infects in fish has a long incubation period, and clinical symptoms are not obvious in the early stages. There is presently no viable and eco-friendly approach to combat the spread of the disease. According to reports, N. seriolae primarily targets macrophages in tissues after infecting fish and can proliferate massively, leading to the death of fish. Interferon-gamma (IFN-γ) is a crucial molecule that regulates macrophage activation, but little is known about its role in the N. seriolae prevention.

Methods

IFN-γ was first defined as largemouth bass (Micropterus salmoides, MsIFN-γ), which has a highly conserved IFN-γ characteristic sequence through homology analysis. The recombinant proteins (rMsIFN-γ) were obtained in Escherichia coli (E. coli) strain BL21 (DE3). The inflammatory response-inducing ability of rMsIFN-γ was assessed in vitro using monocytes/macrophages. Meanwhile, the protective effect of MsIFN-γ in vivo was evaluated by N. seriolae infection largemouth bass model.

Results

In the inflammatory response of the monocytes/macrophages activated by rMsIFN-γ, various cytokines were significantly increased. Interestingly, interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-a) increased by 183- and 12-fold, respectively, after rMsIFN-γ stimulation. rMsIFN-γ improved survival by 42.1% compared with the control. The bacterial load in the liver, spleen and head kidney significantly decreased. rMsIFN-γ was also shown to better induce increased expression of IL-1β, TNF-α, hepcidin-1(Hep-1), major histocompatibility complex I (MHCI), and MHC II in head kidney, spleen and liver. The histopathological examination demonstrated the transformation of granuloma status from an early necrotic foci to fibrosis in the infection period. Unexpectedly, the development of granulomas was successfully slowed in the rMsIFN-γ group.

Discussion

This work paves the way for further research into IFN-γ of largemouth bass and identifies a potential therapeutic target for the prevention of N. seriolae.

A TNF-IL-1 circuit controls Yersinia within intestinal pyogranulomas

Tumor necrosis factor (TNF) is a pleiotropic inflammatory cytokine that mediates antimicrobial defense and granuloma formation in response to infection by numerous pathogens. We previously reported that Yersinia pseudotuberculosis colonizes the intestinal mucosa and induces the recruitment of neutrophils and inflammatory monocytes into organized immune structures termed pyogranulomas (PG) that control Yersinia infection. Inflammatory monocytes are essential for the control and clearance of Yersinia within intestinal PG, but how monocytes mediate Yersinia restriction is poorly understood. Here, we demonstrate that TNF signaling in monocytes is required for bacterial containment following enteric Yersinia infection. We further show that monocyte-intrinsic TNFR1 signaling drives the production of monocyte-derived interleukin-1 (IL-1), which signals through IL-1 receptors on non-hematopoietic cells to enable PG-mediated control of intestinal Yersinia infection. Altogether, our work reveals a monocyte-intrinsic TNF-IL-1 collaborative inflammatory circuit that restricts intestinal Yersinia infection.

Statistical and network analyses reveal mechanisms for the enhancement of macrophage immunity by manganese in Mycobacterium tuberculosis infection

Tuberculosis is a significant infectious disease that poses a serious risk to human health. Our previous research has indicated that manganese ions reduce the bacterial load of Mycobacterium tuberculosis in macrophages, but the exact immune defense mechanism remains unknown. Several critical proteins and pathways involved in the host's immune response during this process are still unidentified. Our research aims to identify these proteins and pathways and provide a rationale for the use of manganese ions in the adjuvant treatment of tuberculosis. We downloaded GSE211666 data from the GEO database and selected the RM (Post-infection manganese ion treatment group) and Ra (single-infection group) groups for comparison and analysis to identify differential genes. These differential genes were then enriched and analyzed using STRING, Cytoscape, and NDEx tools to identify the two most relevant pathways of the "Host Response Signature Network." After conducting an in-depth analysis of these two pathways, we found that manganese ions mainly mediate (1) the interferon -gamma (IFN-γ) and its receptor IFNGR and the downstream JAK-STAT pathway and (2) the NFκB pathway to enhance macrophage response to interferon, autophagy, polarization, and cytokine release. Using qPCR experiments, we verified the increased expression of CXCL10, MHCII, IFNγ, CSF2, and IL12, all of which are cytokines that play a key role in resistance to Mycobacterium tuberculosis infection, suggesting that macrophages enter a state of pro-inflammatory and activation after the addition of manganese ions, which enhances their immunosuppressive effect against Mycobacterium tuberculosis. We conclude that our study provides evidence of manganese ion's ability to treat tuberculosis adjuvantly.

Lipophilic AIEgens as the "Trojan Horse" with Discrepant Efficacy in Tracking and Treatment of Mycobacterial Infection

The highly contagious tuberculosis is a leading infectious killer, which urgently requires effective diagnosis and treatment methods. To address these issues, three lipophilic aggregation-induced emission (AIE) photosensitizers (TTMN, TTTMN, and MeOTTMN) are selected to evaluate their labeling and antimicrobial properties in vitro and in vivo. These three lipophilic AIEgens preserve low cytotoxicity and achieve real-time and non-invasive visualization of the process of mycobacteria infection in vitro and in vivo. More importantly, these AIEgens can be triggered by white light to produce reactive oxygen species (ROS), which is a highly efficient antibacterial reagent. Among these AIEgens, the TTMN photosensitizer has an outstanding antibacterial efficacy over the clinical first-line drug rifampicin at the same therapeutic concentration. Interestingly, this study also finds that TTMN can increase the expression of pro-inflammatory cytokines in the early stage of infection after light irradiation, indicating an additional pro-inflammatory role of TTMN. This work provides some feasibility basis for developing AIEgens-based agents for effectively destroying mycobacterium.

Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis

Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas. Despite major steps in understanding the cause of this disease, many questions remain. In this Review, we perform a mechanistic interrogation of the immune activities that contribute to granuloma formation in sarcoidosis and compare these processes with its closest mimic, tuberculosis, highlighting shared and divergent immune activities. We examine how Mycobacterium tuberculosis is sensed by the immune system; how the granuloma is initiated, formed, and perpetuated in tuberculosis compared with sarcoidosis; and the role of major innate and adaptive immune cells in shaping these processes. Finally, we draw these findings together around several recent high-resolution studies of the granuloma in situ that utilized the latest advances in single-cell technology combined with spatial methods to analyze plausible disease mechanisms. We conclude with an overall view of granuloma formation in sarcoidosis.

CRISPR/Cas9-mediated knockout of tnf-α1 in zebrafish reduces disease resistance after Edwardsiella piscicida bacterial infection

Tumor necrosis factor (TNF) is an important cytokine involved in immune responses to bacterial infections in vertebrates, including fish. Although Tnf-α is a well-studied cytokine, there are contradictory findings about Tnf-α function following bacterial infection. In this study, we analyzed the expression and function of the Tnf-α-type I isoform (Tnf-α1) in zebrafish by knockout experiments using the CRISPR/Cas9 gene-editing tool. The open reading frame of tnf-α1 encodes a 25.82 kDa protein with 234 amino acids (aa). The expression of tnf-α1 in the early stages of zebrafish was observed from the 2-cell stage. Adult zebrafish spleens showed the highest expression of tnf-α1. To evaluate the function of Tnf-α1, an 8 bp deletion in the target region, resulting in a short truncated protein of 55 aa, was used to create the tnf-α1 knockout mutant. The pattern of downstream gene expression in 7-day larvae in wild-type (WT) and tnf-α1 knockout fish was examined. We also verified the fish mortality rate after Edwardsiella piscicida challenge and found that it was much higher in tnf-α1 knockout fish than in WT fish. Additionally, downstream gene expression analyses after E. piscicida exposure revealed a distinct expression pattern in tnf-α1 knockout fish compared to that in WT fish. Overall, our study using tnf-α1 deletion in zebrafish confirmed that Tnf-α1 is critical for immune regulation during bacterial infection.

Mechanopathology of biofilm-like Mycobacterium tuberculosis cords

Mycobacterium tuberculosis (Mtb) cultured axenically without detergent forms biofilm-like cords, a clinical identifier of virulence. In lung-on-chip (LoC) and mouse models, cords in alveolar cells contribute to suppression of innate immune signaling via nuclear compression. Thereafter, extracellular cords cause contact-dependent phagocyte death but grow intercellularly between epithelial cells. The absence of these mechanopathological mechanisms explains the greater proportion of alveolar lesions with increased immune infiltration and dissemination defects in cording-deficient Mtb infections. Compression of Mtb lipid monolayers induces a phase transition that enables mechanical energy storage. Agent-based simulations demonstrate that the increased energy storage capacity is sufficient for the formation of cords that maintain structural integrity despite mechanical perturbation. Bacteria in cords remain translationally active despite antibiotic exposure and regrow rapidly upon cessation of treatment. This study provides a conceptual framework for the biophysics and function in tuberculosis infection and therapy of cord architectures independent of mechanisms ascribed to single bacteria.

Possible Mechanisms of Lymphopenia in Severe Tuberculosis

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). In lymphopenia, T cells are typically characterized by progressive loss and a decrease in their count results. Lymphopenia can hinder immune responses and lead to systemic immunosuppression, which is strongly associated with mortality. Lymphopenia is a significant immunological abnormality in the majority of patients with severe and advanced TB, and its severity is linked to disease outcomes. However, the underlying mechanism remains unclear. Currently, the research on the pathogenesis of lymphopenia during M. tuberculosis infection mainly focuses on how it affects lymphocyte production, survival, or tissue redistribution. This includes impairing hematopoiesis, inhibiting T-cell proliferation, and inducing lymphocyte apoptosis. In this study, we have compiled the latest research on the possible mechanisms that may cause lymphopenia during M. tuberculosis infection. Lymphopenia may have serious consequences in severe TB patients. Additionally, we discuss in detail potential intervention strategies to prevent lymphopenia, which could help understand TB immunopathogenesis and achieve the goal of preventing and treating severe TB.

Immunomodulatory properties of morphine and the hypothesised role of long-term opioid use in the immunopathogenesis of tuberculosis

Epidemiological studies have shown high tuberculosis (TB) prevalence among chronic opioid users. Opioid receptors are found on multiple immune cells and immunomodulatory properties of opioids could be a contributory factor for ensuing immunosuppression and development or reactivation of TB. Toll-like receptors (TLR) mediate an immune response against microbial pathogens, including Mycobacterium tuberculosis. Mycobacterial antigens and opioids co-stimulate TLRs 2/4/9 in immune cells, with resulting receptor cross-talk via multiple cytosolic secondary messengers, leading to significant immunomodulatory downstream effects. Blockade of specific immune pathways involved in the host defence against TB by morphine may play a critical role in causing tuberculosis among chronic morphine users despite multiple confounding factors such as socioeconomic deprivation, Human immunodeficiency virus co-infection and malnutrition. In this review, we map out immune pathways involved when immune cells are co-stimulated with mycobacterial antigens and morphine to explore a potential immunopathological basis for TB amongst long-term opioid users.

Tuberculosis and COVID-19 in the elderly: factors driving a higher burden of disease

Mycobacterium tuberculosis (M.tb) and SARS-CoV-2 are both infections that can lead to severe disease in the lower lung. However, these two infections are caused by very different pathogens (Mycobacterium vs. virus), they have different mechanisms of pathogenesis and immune response, and differ in how long the infection lasts. Despite the differences, SARS-CoV-2 and M.tb share a common feature, which is also frequently observed in other respiratory infections: the burden of disease in the elderly is greater. Here, we discuss possible reasons for the higher burden in older adults, including the effect of co-morbidities, deterioration of the lung environment, auto-immunity, and a reduced antibody response. While the answer is likely to be multifactorial, understanding the main drivers across different infections may allow us to design broader interventions that increase the health-span of older people.

An acidic microenvironment in Tuberculosis increases extracellular matrix degradation by regulating macrophage inflammatory responses

Mycobacterium tuberculosis (M.tb) infection causes marked tissue inflammation leading to lung destruction and morbidity. The inflammatory extracellular microenvironment is acidic, however the effect of this acidosis on the immune response to M.tb is unknown. Using RNA-seq we show that acidosis produces system level transcriptional change in M.tb infected human macrophages regulating almost 4000 genes. Acidosis specifically upregulated extracellular matrix (ECM) degradation pathways with increased expression of Matrix metalloproteinases (MMPs) which mediate lung destruction in Tuberculosis. Macrophage MMP-1 and -3 secretion was increased by acidosis in a cellular model. Acidosis markedly suppresses several cytokines central to control of M.tb infection including TNF-α and IFN-γ. Murine studies demonstrated expression of known acidosis signaling G-protein coupled receptors OGR-1 and TDAG-8 in Tuberculosis which are shown to mediate the immune effects of decreased pH. Receptors were then demonstrated to be expressed in patients with TB lymphadenitis. Collectively, our findings show that an acidic microenvironment modulates immune function to reduce protective inflammatory responses and increase extracellular matrix degradation in Tuberculosis. Acidosis receptors are therefore potential targets for host directed therapy in patients.

Coccidioidomycosis Granulomas Informed by Other Diseases: Advancements, Gaps, and Challenges

Valley fever is a respiratory disease caused by a soil fungus, Coccidioides, that is inhaled upon soil disruption. One mechanism by which the host immune system attempts to control and eliminate Coccidioides is through granuloma formation. However, very little is known about granulomas during Coccidioides infection. Granulomas were first identified in tuberculosis (TB) lungs as early as 1679, and yet many gaps in our understanding of granuloma formation, maintenance, and regulation remain. Granulomas are best defined in TB, providing clues that may be leveraged to understand Coccidioides infections. Granulomas also form during several other infectious and spontaneous diseases including sarcoidosis, chronic granulomatous disease (CGD), and others. This review explores our current understanding of granulomas, as well as potential mechanisms, and applies this knowledge to unraveling coccidioidomycosis granulomas.

Cisatracurium besylate rescues Mycobacterium Tuberculosis-infected macrophages from necroptosis and enhances the bactericidal effect of isoniazid

OBJECTIVE

Tuberculosis is the leading killer among the chronic single-source infectious diseases. Mycobacterium tuberculosis can induce necrotic-dominant multiple modes of cell death in macrophages, which accelerates bacterium dissemination and expands tissue injury in host lungs. Mining drugs to counteract Mycobacterium tuberculosis-induced cell death would be beneficial to tuberculosis patients.

METHODS

In this study, the protective drug was screened out from the FDA-approved drug library in Mycobacterium tuberculosis-infected macrophages with CCK-8 assay. The death mode regulated by the drug was identified using transcriptomic sequencing, cytomorphological observation, and in the experimental mouse Mycobacterium tuberculosis-infection model. The functional mechanism was explored using western blot, co-immunoprecipitation, and DARTS assay. The intracellular bacterial survival was detected using colony forming unit assays.

RESULTS

Cisatracurium besylate was identified to be highly protective for the viability of macrophages during Mycobacterium tuberculosis infection via inhibiting necroptosis. Cisatracurium besylate prevented RIPK3 to be associated with the executive molecule MLKL for forming the necroptotic complex, resulting in the inhibition of MLKL phosphorylation and pore formation on cell membrane. However, Cisatracurium besylate did not interfere with the association between RIPK3 with its upstream kinase RIPK1 or ZBP1 but regulated RIPK3 autophosphorylation. Moreover, Cisatracurium besylate significantly inhibited the expansion of intracellular Mycobacterium tuberculosis both in vitro and in vivo, which also displayed a strong auxiliary bacteriostatic effect to support the therapeutic efficacy of isoniazid and rifampicin, the first-line anti-tubercular drugs.

CONCLUSION

Cisatracurium besylate performs anti-Mycobacterium tuberculosis and anti-necroptotic roles, which potentiates its application to be an adjuvant drug for antituberculosis therapy to assist the battle against drug-resistant tuberculosis.

The host-directed therapeutic imatinib mesylate accelerates immune responses to Mycobacterium marinum infection and limits pathology associated with granulomas

Infections caused by members of the mycobacterium tuberculosis complex [MTC] and nontuberculous mycobacteria [NTM] can induce widespread morbidity and mortality in people. Mycobacterial infections cause both a delayed immune response, which limits rate of bacterial clearance, and formation of granulomas, which contain bacterial spread, but also contribute to lung damage, fibrosis, and morbidity. Granulomas also limit access of antibiotics to bacteria, which may facilitate development of resistance. Bacteria resistant to some or all antibiotics cause significant morbidity and mortality, and newly developed antibiotics readily engender resistance, highlighting the need for new therapeutic approaches. Imatinib mesylate, a cancer drug used to treat chronic myelogenous leukemia [CML] that targets Abl and related tyrosine kinases, is a possible host-directed therapeutic [HDT] for mycobacterial infections, including those causing TB. Here, we use the murine Mycobacterium marinum [Mm] infection model, which induces granulomatous tail lesions. Based on histological measurements, imatinib reduces both lesion size and inflammation of surrounding tissue. Transcriptomic analysis of tail lesions indicates that imatinib induces gene signatures indicative of immune activation and regulation at early time points post infection that resemble those seen at later ones, suggesting that imatinib accelerates but does not substantially alter anti-mycobacterial immune responses. Imatinib likewise induces signatures associated with cell death and promotes survival of bone marrow-derived macrophages [BMDMs] in culture following infection with Mm. Notably, the capacity of imatinib to limit formation and growth of granulomas in vivo and to promote survival of BMDMs in vitro depends upon caspase 8, a key regulator of cell survival and death. These data provide evidence for the utility of imatinib as an HDT for mycobacterial infections in accelerating and regulating immune responses, and limiting pathology associated with granulomas, which may mitigate post-treatment morbidity.

A TNF-IL-1 circuit controls Yersinia within intestinal granulomas

Tumor necrosis factor (TNF) is a pleiotropic inflammatory cytokine that mediates antimicrobial defense and granuloma formation in response to infection by numerous pathogens. Yersinia pseudotuberculosis colonizes the intestinal mucosa and induces recruitment of neutrophils and inflammatory monocytes into organized immune structures termed pyogranulomas that control the bacterial infection. Inflammatory monocytes are essential for control and clearance of Yersinia within intestinal pyogranulomas, but how monocytes mediate Yersinia restriction is poorly understood. Here, we demonstrate that TNF signaling in monocytes is required for bacterial containment following enteric Yersinia infection. We further show that monocyte-intrinsic TNFR1 signaling drives production of monocyte-derived interleukin-1 (IL-1), which signals through IL-1 receptor on non-hematopoietic cells to enable pyogranuloma-mediated control of Yersinia infection. Altogether, our work reveals a monocyte-intrinsic TNF-IL-1 collaborative circuit as a crucial driver of intestinal granuloma function, and defines the cellular target of TNF signaling that restricts intestinal Yersinia infection.

Major Depressive Disorder and Pulmonary Tuberculosis Comorbidity Exacerbates Proinflammatory Immune Response—A Preliminary Study

Background: Major depressive disorders (MDDs) occurs frequently in patients with tuberculosis (TB). Elevated serum pro-inflammatory cytokine levels in MDD patients is a well-established fact. Therefore, an integrated clinical practice should be considered. However, the inflammatory status of MDD-TB patients is unknown. In this study, we analyze cytokines in activated-cells and sera from MDD-TB, TB, MDD patients, and healthy controls. Methods: Flow cytometry was used to evaluate the intracellular production of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-12, and IL-10 by peripheral blood mononuclear cells after a polyclonal stimulation. A Bio-Plex Luminex system was used to measure serum cytokine and chemokine levels in the study groups. Results: We observed a 40.6% prevalence of MDD in TB patients. The proportion of IFN-gamma-producing cells was higher in MDD-TB patients than other pathological groups. Nevertheless, the percentage of TNF-alpha- and IL-12-producing cells was similar between MDD-TB and TB patients. Likewise, MDD-TB and TB patients showed similar serum pro-inflammatory cytokine and chemokine levels, which were significantly lower than those in MDD patients. By multiple correspondence analyses, we observed that low levels of serum IL-4, IL-10, and IL-13 were powerfully associated with TB comorbidities with MDD. Conclusions: A high frequency of IFN-γ-producing cells is associated with low levels of serum anti-inflammatory cytokines in MDD-TB patients.

Molecular Actors of Inflammation and Their Signaling Pathways: Mechanistic Insights from Zebrafish

Inflammation is a hallmark of the physiological response to aggressions. It is orchestrated by a plethora of molecules that detect the danger, signal intracellularly, and activate immune mechanisms to fight the threat. Understanding these processes at a level that allows to modulate their fate in a pathological context strongly relies on in vivo studies, as these can capture the complexity of the whole process and integrate the intricate interplay between the cellular and molecular actors of inflammation. Over the years, zebrafish has proven to be a well-recognized model to study immune responses linked to human physiopathology. We here provide a systematic review of the molecular effectors of inflammation known in this vertebrate and recapitulate their modes of action, as inferred from sterile or infection-based inflammatory models. We present a comprehensive analysis of their sequence, expression, and tissue distribution and summarize the tools that have been developed to study their function. We further highlight how these tools helped gain insights into the mechanisms of immune cell activation, induction, or resolution of inflammation, by uncovering downstream receptors and signaling pathways. These progresses pave the way for more refined models of inflammation, mimicking human diseases and enabling drug development using zebrafish models.

Single-cell profiling identifies ACE+ granuloma macrophages as a nonpermissive niche for intracellular bacteria during persistent Salmonella infection

Macrophages mediate key antimicrobial responses against intracellular bacterial pathogens, such as Salmonella enterica. Yet, they can also act as a permissive niche for these pathogens to persist in infected tissues within granulomas, which are immunological structures composed of macrophages and other immune cells. We apply single-cell transcriptomics to investigate macrophage functional diversity during persistent S. enterica serovar Typhimurium (STm) infection in mice. We identify determinants of macrophage heterogeneity in infected spleens and describe populations of distinct phenotypes, functional programming, and spatial localization. Using an STm mutant with impaired ability to polarize macrophage phenotypes, we find that angiotensin-converting enzyme (ACE) defines a granuloma macrophage population that is nonpermissive for intracellular bacteria, and their abundance anticorrelates with tissue bacterial burden. Disruption of pathogen control by neutralizing TNF is linked to preferential depletion of ACE+ macrophages in infected tissues. Thus, ACE+ macrophages have limited capacity to serve as cellular niche for intracellular bacteria to establish persistent infection.

An intelligent peptide recognizes and traps Mycobacterium tuberculosis to inhibit macrophage phagocytosis

Tuberculosis is a major public health concern worldwide, and it is a serious threat to human health for a long period. Macrophage phagocytosis of Mycobacterium tuberculosis (M. tuberculosis) is a crucial process for granuloma formation, which shelters the bacteria and gives them an opportunity for re-activation and spread. Herein, we report an intelligent anti-microbial peptide that can recognize and trap the M. tuberculosis, inhibiting the macrophage phagocytosis process. The peptide (Bis-Pyrene-KLVFF-WHSGTPH, in abbreviation as BFH) first self-assembles into nanoparticles, and then forms nanofibers upon recognizing and binding M. tuberculosis. Subsequently, BFH traps M. tuberculosis by the in situ formed nanofibrous networks and the trapped M. tuberculosis are unable to invade host cells (macrophages). The intelligent anti-microbial peptide can significantly inhibit the phagocytosis of M. tuberculosis by macrophages, thereby providing a favorable theoretical basis for inhibiting the formation of tuberculosis granulomas.

Tricyclic SpiroLactams Kill Mycobacteria In Vitro and In Vivo by Inhibiting Type II NADH Dehydrogenases

It is critical that novel classes of antituberculosis drugs are developed to combat the increasing burden of infections by multidrug-resistant strains. To identify such a novel class of antibiotics, a chemical library of unique 3-D bioinspired molecules was explored revealing a promising, mycobacterium specific Tricyclic SpiroLactam (TriSLa) hit. Chemical optimization of the TriSLa scaffold delivered potent analogues with nanomolar activity against replicating and nonreplicating Mycobacterium tuberculosis. Characterization of isolated TriSLa-resistant mutants, and biochemical studies, found TriSLas to act as allosteric inhibitors of type II NADH dehydrogenases (Ndh-2 of the electron transport chain), resulting in an increase in bacterial NADH/NAD⁺ ratios and decreased ATP levels. TriSLas are chemically distinct from other inhibitors of Ndh-2 but share a dependence for fatty acids for activity. Finally, in vivo proof-of-concept studies showed TriSLas to protect zebrafish larvae from Mycobacterium marinum infection, suggesting a vulnerability of Ndh-2 inhibition in mycobacterial infections.

Different modalities of host cell death and their impact on Mycobacterium tuberculosis infection

Mycobacterium tuberculosis (Mtb) is the pathogen that causes tuberculosis (TB), a leading infectious disease of humans worldwide. One of the main histopathological hallmarks of TB is the formation of granulomas comprised of elaborately organized aggregates of immune cells containing the pathogen. Dissemination of Mtb from infected cells in the granulomas due to host and mycobacterial factors induces multiple cell death modalities in infected cells. Based on molecular mechanism, morphological characteristics, and signal dependency, there are two main categories of cell death: programmed and nonprogrammed. Programmed cell death (PCD), such as apoptosis and autophagy, is associated with a protective response to Mtb by keeping the bacteria encased within dead macrophages that can be readily phagocytosed by arriving in uninfected or neighboring cells. In contrast, non-PCD necrotic cell death favors the pathogen, resulting in bacterial release into the extracellular environment. Multiple types of cell death in the PCD category, including pyroptosis, necroptosis, ferroptosis, ETosis, parthanatos, and PANoptosis, may be involved in Mtb infection. Since PCD pathways are essential for host immunity to Mtb, therapeutic compounds targeting cell death signaling pathways have been experimentally tested for TB treatment. This review summarizes different modalities of Mtb-mediated host cell deaths, the molecular mechanisms underpinning host cell death during Mtb infection, and its potential implications for host immunity. In addition, targeting host cell death pathways as potential therapeutic and preventive approaches against Mtb infection is also discussed.

mTOR-regulated mitochondrial metabolism limits mycobacterium-induced cytotoxicity

Necrosis of macrophages in the granuloma, the hallmark immunological structure of tuberculosis, is a major pathogenic event that increases host susceptibility. Through a zebrafish forward genetic screen, we identified the mTOR kinase, a master regulator of metabolism, as an early host resistance factor in tuberculosis. We found that mTOR complex 1 protects macrophages from mycobacterium-induced death by enabling infection-induced increases in mitochondrial energy metabolism fueled by glycolysis. These metabolic adaptations are required to prevent mitochondrial damage and death caused by the secreted mycobacterial virulence determinant ESAT-6. Thus, the host can effectively counter this early critical mycobacterial virulence mechanism simply by regulating energy metabolism, thereby allowing pathogen-specific immune mechanisms time to develop. Our findings may explain why Mycobacterium tuberculosis, albeit humanity's most lethal pathogen, is successful in only a minority of infected individuals.

Transcriptome profiling reveals toxicity mechanisms following sertraline exposure in the brain of juvenile zebrafish (Danio rerio)

Sertraline (SER) is one of the most commonly detected antidepressants in the aquatic environment that can negatively affect aquatic organisms at low concentrations. Despite some knowledge on its acute toxicity to fish, the effects of chronic SER exposure remain poorly understood along with any underlying mechanisms of SER-induced toxicity. To address this knowledge gap, the effects of chronic exposure to three SER concentrations from low to high were investigated in zebrafish. Juvenile zebrafish were exposed to three concentrations of 1, 10, or 100 μg/L of SER for 28 d, after which indicators of oxidative stress and neurotoxicity in the brain were measured. Superoxide dismutase (SOD) activity was significantly enhanced by SER at 1 up to 100 μg/L, and catalase (CAT) activity was significantly induced by SER at 1 or 10 μg/L. The activity of acetylcholinesterase (AChE) was significantly induced by 10 and 100 μg/L of SER, and the serotonin (5-HT) level was significantly increased by all three concentrations of SER. To ascertain mechanisms of SER-induced toxicity, transcriptomics was conducted in the brain of zebrafish following 100 μg/L SER exposure. The molecular signaling pathways connected with circadian system and the immune system were significantly altered in the zebrafish brain. Based on transcriptomic data, the expression levels of six circadian clock genes were measured, and three genes were significantly altered in relative abundance in fish from all experimental treatments with SER, including cryptochrome circadian regulator 2 (cry2), period circadian clock 2 (per2), and period circadian clock 3 (per3). We hypothesize that the circadian system may be related to SER-induced neurotoxicity and oxidative stress in the central nervous system. This study reveals potential mechanisms and key events (i.e., oxidative stress and neurotoxicity) associated with SER-induced toxicity, and improves understanding of the molecular and biochemical pathways putatively perturbed by SER.

Tibetan medicine salidroside improves host anti-mycobacterial response by boosting inflammatory cytokine production in zebrafish

The treatment for tuberculosis (TB), especially multidrug-resistant TB (MDR-TB), has a prolonged cycle which can last up to a year. This is partially due to the lack of effective therapies. The development of novel anti-TB drugs from the perspective of host immune regulation can provide an important supplement for conventional treatment strategies. Salidroside (SAL), a bioactive component from the Tibetan medicine Rhodiola rosea, has been used in the treatment of TB, although its mechanism remains unclear. Here, the bacteriostatic effect of SAL in vivo was first demonstrated using a zebrafish–M. marinum infection model. To further investigate the underlying mechanism, we then examined the impact of SAL on immune cell recruitment during wound and infection. Increased macrophage and neutrophil infiltrations were found both in the vicinity of the wound and infection sites after SAL treatment compared with control, which might be due to the elevated chemokine expression levels after SAL treatment. SAL treatment alone was also demonstrated to improve the survival of infected zebrafish larvae, an effect that was amplified when combining SAL treatment with isoniazid or rifampicin. Interestingly, the reduced bacterial burden and improved survival rate under SAL treatment were compromised in tnfα-deficient embryos which suggests a requirement of Tnfα signaling on the anti-mycobacterial effects of SAL. In summary, this study provides not only the cellular and molecular mechanisms for the host anti-mycobacterial effects of the Tibetan medicine SAL but also proof of concept that combined application of SAL with traditional first-line anti-TB drugs could be a novel strategy to improve treatment efficacy.

Short-term effect of sulfur dioxide (SO2) change on the risk of tuberculosis outpatient visits in 16 cities of Anhui Province, China: the first multi-city study to explore differences in occupational patients

A growing number of biological studies suggest that exogenous sulfur dioxide (SO₂) at a certain concentration may promote human resistance to Mycobacterium tuberculosis. However, the results of most relevant studies are inconsistent, and few studies have explored the relationship between SO₂ exposure and tuberculosis risk at provincial level. In addition, occupational exposure has long been considered to have a certain impact on the human body, so for the first time, we discussed the differences between different occupations in the study on the relationship between air pollutant exposure and tuberculosis risk, and evaluated the impact of occupational exposure. This study aimed to explore the association between short-term SO₂ exposure and the risk of outpatient visits to tuberculosis in Anhui province and 16 prefecture-level cities from 2015 to 2020. We used several models for multi-stage analysis, including distributed lag nonlinear model (DLNM), Poisson generalized linear regression model, and random-effects model. The association was assessed using the 28-day cumulative lag effect RR and 95%CI for each 10-unit increase in SO₂ concentration. We divided all patients into the following six occupations: Worker, Farmer, Retired people, Children and Students, Cadre and Office clerk, and Service staff (catering, business, etc.). Sex, age, and season were analyzed by subgroup. Finally, the robustness of the multi-pollutant model was tested. At provincial level, the overall effect value of SO₂ was RR=0.8191 (95%CI: 07702~0.8712); after grouping all patients by occupation, the association found only among Farmers (RR = 0.7150, 95%CI: 0.6699-0.7632, lag 0-28 days) and Workers (RR = 0.8566, 95%CI: 0.7930-0.9930, lag 0-4 days) was still statistically significant. Estimates for individual cities and using random-effects models to estimate average associations showed that SO₂ exposure was associated with a reduced risk of outpatient TB visits in 14 municipalities, which remained significant when aggregated (RR = 0.9030, 95%CI: 0.8730-0.9340). Analysis of patients grouped by occupation in each municipality showed that statistical significance was again observed only in the Farmer (RR = 0.8880, 95%CI: 0.8610-0.9160) and Worker (RR = 0.8250, 95%CI: 0.7290-0.9340) groups. Stratified analysis of age, sex, and season showed that the effect of SO₂ exposure was greater for middle-aged people (18-64 years old) and males, and less for seasonal changes. In summary, we found that exposure to SO₂ reduces the risk of outpatient visits to tuberculosis, with farmers and workers more susceptible to SO₂. Gender and age had a greater impact on the risk of TB outpatient visits than seasonal variations.

Tumor necrosis factor induces pathogenic mitochondrial ROS in tuberculosis through reverse electron transport

Tumor necrosis factor (TNF) is a critical host resistance factor against tuberculosis. However, excess TNF produces susceptibility by increasing mitochondrial reactive oxygen species (mROS), which initiate a signaling cascade to cause pathogenic necrosis of mycobacterium-infected macrophages. In zebrafish, we identified the mechanism of TNF-induced mROS in tuberculosis. Excess TNF in mycobacterium-infected macrophages elevates mROS production by reverse electron transport (RET) through complex I. TNF-activated cellular glutamine uptake leads to an increased concentration of succinate, a Krebs cycle intermediate. Oxidation of this elevated succinate by complex II drives RET, thereby generating the mROS superoxide at complex I. The complex I inhibitor metformin, a widely used antidiabetic drug, prevents TNF-induced mROS and necrosis of Mycobacterium tuberculosis-infected zebrafish and human macrophages; metformin may therefore be useful in tuberculosis therapy.

E3 Ligase FBXW7 Facilitates Mycobacterium Immune Evasion by Modulating TNF-α Expression

Tumor necrosis factor alpha (TNF-α) is a crucial factor in the control of Mycobacterium tuberculosis (Mtb) infection. Pathogenic mycobacteria can inhibit and/or regulate host cell TNF-α production in a variety of ways to evade antituberculosis (anti-TB) immunity as well as facilitate immune escape. However, the mechanisms by which TNF-α expression in host cells is modulated to the benefit of mycobacteria is still an interesting topic and needs further study. Here, we report that macrophages infected with Mycobacterium marinum (Mm)—a close relative of Mtb—upregulated the expression of E3 ubiquitin ligase FBXW7. Specific silencing FBXW7 with small interfering RNA (siRNA) significantly elevates TNF-α expression and eventually promotes the elimination of intracellular bacteria. In turn, overexpression of FBXW7 in Raw264.7 macrophages markedly decreased TNF-α production. Furthermore, partial inhibition of FBXW7 in an Mm-infected murine model significantly reduced TNF-α tissue content, alleviated tissue damage as well as reduced the bacterial load of mouse tails. Finally, FBXW7 could decrease TNF-α in a K63-linked ubiquitin signaling dependent manner. Taken together, our study uncovered a previously unknown role of FBXW7 in regulating TNF-α dynamics during mycobacterial infection, which provides new insights into understanding the role of FBXW7 in anti-tuberculosis immunity and its related clinical significance.

Antibiotic Management of Patients with Hematologic Malignancies: From Prophylaxis to Unusual Infections

Purpose of Review

Patients with hematological malignancies are recognized for their high susceptibility and increased risk of developing infections associated with immunosuppression that can be caused by the infection itself or by the treatments that condition a decrease in the humoral and T lymphocyte response, so this review attempts to gather the main bacterial, viral, parasitic, and fungal agents that affect them and give recommendations for their approach and diagnosis.

Recent Findings

In recent years, with the discovery and use of new therapies including immunological and targeted treatments, it has been possible to improve the survival and response of patients with hematological malignancies; however, antimicrobial resistance has also increased; we have faced new and unknown microorganisms, such as the SARS-CoV-2 that caused the COVID-19 pandemic in the past year, and therefore, new risks and more severe infections are presented.

Summary

We present a review of the different circumstances where hematological malignancies increased the risk of infections and which microorganisms affect these patients, their characteristics, and the suggested prophylaxis.

In the Thick of It: Formation of the Tuberculous Granuloma and Its Effects on Host and Therapeutic Responses

The defining pathology of tuberculosis is the granuloma, an organized structure derived from host immune cells that surrounds infecting Mycobacterium tuberculosis. As the location of much of the bacteria in the infected host, the granuloma is a central point of interaction between the host and the infecting bacterium. This review describes the signals and cellular reprogramming that drive granuloma formation. Further, as a central point of host-bacterial interactions, the granuloma shapes disease outcome by altering host immune responses and bacterial susceptibility to antibiotic treatment, as discussed herein. This new understanding of granuloma biology and the signaling behind it highlights the potential for host-directed therapies targeting the granuloma to enhance antibiotic access and tuberculosis-specific immune responses.

TNF inhibitors increase the risk of nontuberculous mycobacteria in patients with seropositive rheumatoid arthritis in a mycobacterium tuberculosis endemic area

The aim of this study is to examine the impact of tumor necrosis factor inhibitors (TNFI) on nontuberculous mycobacterium (NTM) infection in rheumatoid arthritis (RA) patients in a mycobacterium tuberculosis (MTB) endemic area. We selected 1089 TNFI-treated RA patients and 4356 untreated RA patients using propensity-matching analysis according to age, gender, and Charlson comorbidity index using the Korean National Health Insurance Service database from July 2009 to December 2010. Both groups were followed-up until the end of 2016 to measure the incidence of mycobacterial diseases. The incidence rate of NTM in TNFI-treated RA group was similar to those of MTB (328.1 and 340.9 per 100,000 person-years, respectively). The adjusted hazard ratio (aHR) of NTM for TNFI-treated RA compared to untreated RA was 1.751(95% CI 1.105-2.774). The risk of TNFI-associated NTM in RA was 2.108-fold higher among women than men. The age-stratified effects of TNFI on NTM development were significantly high in RA patients aged 50-65 years (aHR 2.018). RA patients without comorbidities had a higher incidence of NTM following TNFI treatment (aHR 1.742). This real-world, observational study highlights the need to increase awareness of NTM in TNFI-treated RA patients in an MTB endemic area.

mtROS Induced via TLR-2-SOCE Signaling Plays Proapoptotic and Bactericidal Role in Mycobacterium fortuitum-Infected Head Kidney Macrophages of Clarias gariepinus

The mechanisms underlying Mycobacterium fortuitum-induced mycobacteriosis remain unexplored. Using head kidney macrophages (HKM) from catfish (Clarias gariepinus), we report that Ca²⁺ surge across mitochondrial-Ca²⁺ uniporter (MICU), and consequent mitochondrial ROS (mtROS) production, is imperative for mycobactericidal activity. Inhibition of mtROS alleviated HKM apoptosis and enhanced bacterial survival. Based on RNA interference (RNAi) and inhibitor studies, we demonstrate that the Toll-like receptor (TLR)-2–endoplasmic reticulum (ER) stress–store-operated calcium entry (SOCE) axis is instrumental for activating the mt-Ca²⁺/mtROS cascade in M. fortuitum-infected HKM. Additionally, pharmacological inhibition of mtROS attenuated the expression of CHOP, STIM1, and Orai1, which suggests a positive feedback loop between ER-stress-induced SOCE and mtROS production. Elevated tumor necrosis factor alpha (TNF-α) levels and caspase-8 activity were observed in HKM consequent to M. fortuitum infection, and our results implicate that mtROS is crucial in activating the TNF-mediated caspase-8 activation. Our results for the first time demonstrate mitochondria as an innate immune signaling center regulating mycobacteriosis in fish. We conclude that M. fortuitum-induced persistent SOCE signaling leads to mtROS production, which in turn activates the TNF-α/caspase-8 axis culminating in HKM apoptosis and bacterial clearance.

The Tuberculous Granuloma and Preexisting Immunity

Pulmonary granulomas are widely considered the epicenters of the immune response to Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB). Recent animal studies have revealed factors that either promote or restrict TB immunity within granulomas. These models, however, typically ignore the impact of preexisting immunity on cellular organization and function, an important consideration because most TB probably occurs through reinfection of previously exposed individuals. Human postmortem research from the pre-antibiotic era showed that infections in Mtb-naïve individuals (primary TB) versus those with prior Mtb exposure (postprimary TB) have distinct pathologic features. We review recent animal findings in TB granuloma biology, which largely reflect primary TB. We also discuss our current understanding of postprimary TB lesions, about which much less is known. Many knowledge gaps remain, particularly regarding how preexisting immunity shapes granuloma structure and local immune responses at Mtb infection sites.

Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Lumpfish (Cyclopterus lumpus) Is Susceptible to Renibacterium salmoninarum Infection and Induces Cell-Mediated Immunity in the Chronic Stage

Renibacterium salmoninarum is a Gram-positive, intracellular pathogen that causes Bacterial Kidney Disease (BKD) in several fish species in freshwater and seawater. Lumpfish (Cyclopterus lumpus) is utilized as a cleaner fish to biocontrol sea lice infestation in Atlantic salmon (Salmo salar) farms. Atlantic salmon is susceptible to R. salmoninarum, and it can transfer the infection to other fish species. Although BKD outbreaks have not been reported in lumpfish, its susceptibility and immune response to R. salmoninarum is unknown. In this study, we evaluated the susceptibility and immune response of lumpfish to R. salmoninarum infection. Groups of lumpfish were intraperitoneally (i.p.) injected with either R. salmoninarum (1×10⁷, 1×10⁸, or 1×10⁹ cells dose^-1) or PBS (control). R. salmoninarum infection kinetics and mortality were followed for 98 days post-infection (dpi). Transcript expression levels of 33 immune-relevant genes were measured in head kidney (n = 6) of fish infected with 1×10⁹ cells/dose and compared to the control at 28 and 98 dpi. Infected lumpfish displayed characteristic clinical signs of BKD. Lumpfish infected with high, medium, and low doses had a survival rate of 65%, 93%, and 95%, respectively. Mortality in the high-dose infected group stabilized after 50 dpi, but R. salmoninarum persisted in the fish tissues until 98 dpi. Cytokines (il1β, il8a, il8b), pattern recognition receptors (tlr5a), interferon-induced effectors (rsad2, mxa, mxb, mxc), and iron regulation (hamp) and acute phase reactant (saa5) related genes were up-regulated at 28 dpi. In contrast, cell-mediated adaptive immunity-related genes (cd4a, cd4b, ly6g6f, cd8a, cd74) were down-regulated at 28 dpi, revealing the immune suppressive nature of R. salmoninarum. However, significant upregulation of cd74 at 98 dpi suggests induction of cell-mediated immune response. This study showed that R. salmoninarum infected lumpfish in a similar fashion to salmonid fish species and caused a chronic infection, enhancing cell-mediated adaptive immune response.

Pre-injection of Zebrafish (Danio rerio) tnfb Polyclonal Antibody Decreases the Mortality of Vibrio vulnificus Infected Zebrafish

Tumor necrosis factor (TNF) plays an important role in an inflammatory cytokine storm. Over-secretion of TNF by the host in response to infection aggravates the disease. TNF expression level is positively correlated with the mortality caused by some bacterial infections. Therefore, using TNF antibody may alleviate the inflammation to resist bacterial infections. The function of fish TNF-b antibody in bacterial infection is still unclear. In this study, infection models of Vibrio vulnificus FJ03-X2 strain with high pathogenicity and strong virulence were established in zebrafish (Danio rerio) fibroblast cell line (ZF4 cells) and zebrafish. Zebrafish tnfb (Zetnf-b) gene was cloned and expressed by Escherichia coli BL21 (DE3), and Zetnf-b polyclonal antibody was prepared. Pre-injection of Zetnf-b polyclonal antibody and AG-126 before infecting with V. vulnificus could increase the survival rate of zebrafish by 36.6 and 46.7%, respectively. Pre-injection of Zetnf-b polyclonal antibody could effectively decrease the mortality of zebrafish infected by V. vulnificus. Thus, TNF polyclonal antibody therapy could be considered as an effective strategy to control V. vulnificus in fish.

Pathogenetic role of tumor necrosis factor (TNF-α) for the development of peritoneal tuberculosis in an experiment

Currently tuberculosis is considered as a group of diseases united by one etiological factor. The pathogenesis of certain localizations of tuberculous inflammation, in particular peritoneum tuberculosis, hasn’t been sufficiently studied. The role of cytokine mechanisms in the development of the disease and the elaboration of non-sterile immunity requires further experimental studies, in particular the creation of a reproducible model on laboratory animals.

The aim: to study the effect of TNF-α on the development of tuberculosis of the serous coat of the abdominal cavity, as well as to evaluate the possibility of modeling tuberculous peritonitis in laboratory animals using infliximab.

Materials and methods. The studies were conducted on 18 male rabbits, which were simulated peritoneal tuberculosis by intra-abdominal administration of a suspension of Mycobacterium tuberculosis. 10 rabbits of the experimental group were intravenously injected with an infliximab solution and an iron (III) hydroxide sucrose complex intraperitoneally a day before infection.

Results. In the control group of animals, tuberculosis either didn’t develop, or in a third of cases it affected only the pulmonary parenchyma, while proliferative processes prevailed. On the contrary, in animals with inactivated TNF-α, in 100 % of observations, tuberculous peritonitis was detected with associated lung damage and the predominance of alterative caseous processes.

Conclusion. The created model of tuberculous peritonitis shows the leading role of TNF-α in the activation of macrophages, as well as in attracting cells to the site of infection. This is the primary signal necessary for the formation and stability of granulomas since the neutralization of this cytokine leads to a loss of control over the infection and the destruction of the granuloma with the development of destructive tuberculosis in the serous coat of the abdominal cavity. 

Monocyte-related gene biomarkers for latent and active tuberculosis

Monocytes are closely associated with tuberculosis (TB). Latent tuberculosis in some patients gradually develops into its active state. This study aimed to investigate the role of hub monocyte-associated genes in distinguishing latent TB infection (LTBI) from active TB. The gene expression profiles of 15 peripheral blood mononuclear cells (PBMCs) samples were downloaded from the gene expression omnibus (GEO) database, GSE54992. The monocyte abundance was high in active TB as evaluated by the Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) algorithm. The limma test and correlation analysis documented 165 differentially expressed monocyte-related genes (DEMonRGs) between latent TB and active TB. Functional annotation and enrichment analyses of the DEMonRGs using the database for annotation, visualization, and integration discovery (DAVID) tools showed enrichment of inflammatory response mechanisms and immune-related pathways. A protein-protein interaction network was constructed with a node degree ≥10. The expression levels of these hub DEMonRGs (SERPINA1, FUCA2, and HP) were evaluated and verified using several independent datasets and clinical settings. Finally, a single sample scoring method was used to establish a gene signature for the three DEMonRGs, distinguishing active TB from latent TB. The findings of the present study provide a better understanding of monocyte-related molecular fundamentals in TB progression and contribute to the identification of new potential biomarkers for the diagnosis of active TB.

M. fortuitum-induced CNS-pathology: Deciphering the role of canonical Wnt signaling, blood brain barrier components and cytokines

Molecular underpinning of mycobacteria-induced CNS-pathology is not well understood. In the present study, zebrafish were infected with Mycobacterium fortuitum and the prognosis of CNS-pathogenesis studied. We observed M. fortuitum triggers extensive brain-pathology. Evans blue extravasation demonstrated compromised blood-brain barrier (BBB) integrity. Further, decreased expression in tight-junction (TJ) and adherens junction complex (AJC) genes were noted in infected brain. Wnt-signaling has emerged as a major player in host-mycobacterial immunity but its involvement/role in brain-infection is not well studied. Sustained expression of wnt2, wnt3a, fzd5, lrp5/6 and β-catenin, with concordant decline in degradation complex components axin, gsk3β and β-catenin regulator capn2a were observed. The surge in ifng1 and tnfa expression preceding il10 and il4 suggested cytokine-interplay critical in M. fortuitum-induced brain-pathology. Therefore, we suggest adult zebrafish as a viable model for studying CNS-pathology and using the same, conclude that M. fortuitum infection is associated with repressed TJ-AJC gene expression and compromised BBB permeability. Our results implicate Wnt/β-catenin pathway in M. fortuitum-induced CNS-pathology wherein Th1-type signals facilitate bacterial clearance and Th2-type signals prevent the disease sequel.

Single Nucleotide Polymorphisms of Immunity-Related Genes and Their Effects on Immunophenotypes in Different Pig Breeds

Enhancing resistance and tolerance to pathogens remains an important selection objective in the production of livestock animals. Single nucleotide polymorphisms (SNPs) vary gene expression at the transcriptional level, influencing an individual's immune regulation and susceptibility to diseases. In this study, we investigated the distribution of SNP sites in immune-related genes and their correlations with cell surface markers of immune cells within purebred (Taiwan black, Duroc, Landrace and Yorkshire) and crossbred (Landrace-Yorkshire) pigs. Thirty-nine SNPs of immune-related genes, including 11 cytokines, 5 chemokines and 23 Toll-like receptors (TLRs) (interferon-α and γ (IFN-α, γ), tumor necrosis factor-α (TNF-α), granulocyte-macrophage colony-stimulating factor (GM-CSF), Monocyte chemoattractant protein-1 (MCP-1) and TLR3, TLR4, TLR7, TLR8, and TLR9) were selected, and the percentages of positive cells with five cell surface markers of CD4, CD8, CD80/86, MHCI, and MHCII were analyzed. There were 28 SNPs that were significantly different among breeds, particularly between Landrace and Taiwan black. For instance, the frequency of SNP1 IFN-α -235A/G in Taiwan black and Landrace was 11.11% and 96.15%, respectively. In addition, 18 SNPs significantly correlated with the expression of cell surface markers, including CD4, CD8, CD80/86, and MHCII. The percentage of CD4+ (39.27%) in SNP33 TLR-8 543C/C was significantly higher than those in A/C (24.34%), at p < 0.05. Together, our findings show that Taiwan black pigs had a unique genotype distribution, whereas Landrace and Yorkshire had a more similar genotype distribution. Thus, an understanding of the genetic uniqueness of each breed could help to identify functionally important SNPs in immunoregulation.

The Role of Galanin during Bacterial Infection in Larval Zebrafish

Galanin is a peptide that is conserved among different species and plays various roles in an organism, although its entire role is not completely understood. For many years, galanin has been linked mainly with the neurotransmission in the nervous system; however, recent reports underline its role in immunity. Zebrafish (Danio rerio) is an intensively developing animal model to study infectious diseases. In this study, we used larval zebrafish to determine the role of galanin in bacterial infection. We showed that knockout of galanin in zebrafish leads to a higher bacterial burden and mortality during Mycobacterium marinum and Staphylococcus aureus infection, whereas administration of a galanin analogue, NAX 5055, improves the ability of fish to control the infection caused by both pathogens. Moreover, the transcriptomics data revealed that a lower number of genes were regulated in response to mycobacterial infection in gal−/− mutants compared with their gal+/+ wild-type counterparts. We also found that galanin deficiency led to significant changes in immune-related pathways, mostly connected with cytokine and chemokine functions. The results show that galanin acts not only as a neurotransmitter but is also involved in immune response to bacterial infections, demonstrating the complexity of the neuroendocrine system and its possible connection with immunity.

Protective Efficacy of Novel Oral Biofilm Vaccines against Lactococcus garvieae Infection in Mullet, Mugil cephalus

Lactococcus garvieae (L. garvieae) is an important pathogen that causes enormous economic losses in both marine and freshwater aquaculture. At present, antibiotics are the only option for farmers to reduce the losses caused by L. garvieae. However, the usage of antibiotics leads to environmental pollution and the production of drug-resistant strains of bacteria. Therefore, vaccination is preferred as an alternative method to prevent infectious diseases. In this study, we describe an effective approach to the production of an oral biofilm vaccine, using bacteria grown on chitosan particles to form biofilms, and thus providing an inactive pathogen that enhances the immune response in fish. We observed the formation of a biofilm on chitosan particles and administered the novel oral biofilm vaccine to fish. We analyzed the immune responses, including antibody production, phagocytic ability, albumin/globulin ratio and immune-related genes, of vaccinated and control groups of black mullet. Our results show that the phagocytic ability of the biofilm vaccine group was 84%, which is significantly higher than that of the control group, and the antibody production in this group was significantly higher compared with the other group. The mRNA expression levels of immune-related genes (TLR2, IL-1β, TNF-α) were significantly upregulated in the spleen after vaccination. In challenge experiments, the relative percent survival (RPS) was 77% in the biofilm vaccine group, 18% in the whole-cell vaccine group, and 0% in the chitosan particle group at 32 days post-vaccination. In addition, we also found that the relative percent survival (RPS) at 1 day post-vaccination was 74% in the biofilm vaccine group, 42% in the whole-cell vaccine group, and 26% in the chitosan particle group. In both long-term and short-term challenge experiments, the viability of the biofilm vaccine group was significantly higher than that of the whole-cell, chitosan particle and PBS groups. We conclude that based on its protective effect, the L. garvieae biofilm vaccine is better than the whole-cell vaccine when challenged several weeks after vaccination. In addition, the biofilm vaccine also has a greater protective effect than the whole-cell vaccine when challenged immediately after vaccination. Therefore, the biofilm vaccine might represent a novel method for the prevention and treatment of L. garvieae infection.

Multifunctional T cell response in active pulmonary tuberculosis patients

BACKGROUND

Tuberculosis still threatens human health. We aimed to investigate the T cell immune status and the role of multifunctional T cells in pulmonary tuberculosis patients.

METHODS

Thirty active pulmonary tuberculosis (APTB) patients, 30 latent tuberculosis infection (LTBI) patients, 25 cured pulmonary tuberculosis (CPTB) patients and 25 healthy controls (HCs) enrolled in this study. Flow cytometer for detecting T cell phenotype and function. CBA Flex Set was used to measure chemokine.

RESULTS

Compared with HCs and LTBI patients, APTB patients had fewer CD4⁺ T and CD8⁺ T cells, but the expression of granzyme A, granzyme B and perforin on CD8⁺ T cells increased. Compared to LTBI and CPTB patients, Mycobacterium tuberculosis-specific CD8⁺ T cells in APTB patients appeared to be more differentiated CD45RA^-CCR7^- cells, and there were more multifunctional CD4⁺ T and CD8⁺ T cells. Importantly, the frequency of multifunctional CD4⁺ T cells in the pleural fluid of APTB patients was higher than that of peripheral blood. And the proportion of multifunctional CD4⁺ T cells expressing the migration receptor CXCR3 in the peripheral blood of APTB patients decreased, while the concentrations of its ligands, chemokine MIG, IP-10 and I-TAC increased significantly in plasma, especially in pleural fluid.

CONCLUSIONS

Decreased T lymphocytes in APTB patients may cause compensatory activation of CD8⁺ T cells. Multifunctional CD4⁺ T cells in peripheral blood could migrate to the lungs under the action of CXCR3 and associated chemokine. Multifunctional CD4⁺ T cells and Multifunctional CD8⁺ T cells were of great significance in monitoring disease treatment.