Necrotic cell death during
(Mtb) infection is considered host detrimental since it facilitates mycobacterial spread. Ferroptosis is a type of regulated necrosis induced by accumulation of free iron ...and toxic lipid peroxides. We observed that Mtb-induced macrophage necrosis is associated with reduced levels of glutathione and glutathione peroxidase-4 (Gpx4), along with increased free iron, mitochondrial superoxide, and lipid peroxidation, all of which are important hallmarks of ferroptosis. Moreover, necrotic cell death in Mtb-infected macrophage cultures was suppressed by ferrostatin-1 (Fer-1), a well-characterized ferroptosis inhibitor, as well as by iron chelation. Additional experiments in vivo revealed that pulmonary necrosis in acutely infected mice is associated with reduced Gpx4 expression as well as increased lipid peroxidation and is likewise suppressed by Fer-1 treatment. Importantly, Fer-1-treated infected animals also exhibited marked reductions in bacterial load. Together, these findings implicate ferroptosis as a major mechanism of necrosis in Mtb infection and as a target for host-directed therapy of tuberculosis.
Infection of host cells by Toxoplasma gondii is an active process, which is regulated by secretion of microneme (MICs) and rhoptry proteins (ROPs and RONs) from specialized organelles in the apical ...pole of the parasite. MIC1, MIC4 and MIC6 assemble into an adhesin complex secreted on the parasite surface that functions to promote infection competency. MIC1 and MIC4 are known to bind terminal sialic acid residues and galactose residues, respectively and to induce IL-12 production from splenocytes. Here we show that rMIC1- and rMIC4-stimulated dendritic cells and macrophages produce proinflammatory cytokines, and they do so by engaging TLR2 and TLR4. This process depends on sugar recognition, since point mutations in the carbohydrate-recognition domains (CRD) of rMIC1 and rMIC4 inhibit innate immune cells activation. HEK cells transfected with TLR2 glycomutants were selectively unresponsive to MICs. Following in vitro infection, parasites lacking MIC1 or MIC4, as well as expressing MIC proteins with point mutations in their CRD, failed to induce wild-type (WT) levels of IL-12 secretion by innate immune cells. However, only MIC1 was shown to impact systemic levels of IL-12 and IFN-γ in vivo. Together, our data show that MIC1 and MIC4 interact physically with TLR2 and TLR4 N-glycans to trigger IL-12 responses, and MIC1 is playing a significant role in vivo by altering T. gondii infection competency and murine pathogenesis.
Leprosy, also known as Hansen's, is one of the listed neglected tropical diseases as a major health problem global. Treatment is one of the main alternatives, however, the scarcity of medication and ...its poor distribution are important factors that have driven the spread of the disease, leading to irreversible and multi-resistant complications. This paper uses a distribution methodology to optimize medication administration, taking into account the most relevant attributes for the epidemiological profile of patients and the deficit in treatment via Polychemotherapy. Multi-criteria Decision Methods were applied based on AHP-Electre model in a database with information from patients in the state of Para between 2015 and 2020. The results pointed out that 84% of individuals did not receive any treatment and, among these, the method obtained a gain in the distribution of 68% in patients with positive diagnosis for leprosy.
Mycobacterium tuberculosis infection is thought to induce oxidative stress. N-acetyl-cysteine (NAC) is widely used in patients with chronic pulmonary diseases including tuberculosis due to its ...mucolytic and anti-oxidant activities. Here, we tested whether NAC exerts a direct antibiotic activity against mycobacteria.
Oxidative stress status in plasma was compared between pulmonary TB (PTB) patients and those with latent M. tuberculosis infection (LTBI) or healthy uninfected individuals. Lipid peroxidation, DNA oxidation and cell death, as well as accumulation of reactive oxygen species (ROS) were measured in cultures of primary human monocyte-derived macrophages infected with M. tuberculosis and treated or not with NAC. M. tuberculosis, M. avium and M. bovis BCG cultures were also exposed to different doses of NAC with or without medium pH adjustment to control for acidity. The anti-mycobacterial effect of NAC was assessed in M. tuberculosis infected human THP-1 cells and bone marrow-derived macrophages from mice lacking a fully functional NADPH oxidase system. The capacity of NAC to control M. tuberculosis infection was further tested in vivo in a mouse (C57BL/6) model.
PTB patients exhibited elevated levels of oxidation products and a reduction of anti-oxidants compared with LTBI cases or uninfected controls. NAC treatment in M. tuberculosis-infected human macrophages resulted in a decrease of oxidative stress and cell death evoked by mycobacteria. Importantly, we observed a dose-dependent reduction in metabolic activity and in vitro growth of NAC treated M. tuberculosis, M. avium and M. bovis BCG. Furthermore, anti-mycobacterial activity in infected macrophages was shown to be independent of the effects of NAC on the host NADPH oxidase system in vitro. Short-term NAC treatment of M. tuberculosis infected mice in vivo resulted in a significant reduction of mycobacterial loads in the lungs.
NAC exhibits potent anti-mycobacterial effects and may limit M. tuberculosis infection and disease both through suppression of the host oxidative response and through direct antimicrobial activity.
Effective treatment of Mycobacterium tuberculosis (Mtb) infection requires at least 6 months of daily therapy with multiple orally administered antibiotics. Although this drug regimen is administered ...annually to millions worldwide, the impact of such intensive antimicrobial treatment on the host microbiome has never been formally investigated. Here, we characterized the longitudinal outcome of conventional isoniazid-rifampin-pyrazinamide (HRZ) TB drug administration on the diversity and composition of the intestinal microbiota in Mtb-infected mice by means of 16S rRNA sequencing. We also investigated the effects of each of the individual antibiotics alone and in different combinations.
While inducing only a transient decrease in microbial diversity, HRZ treatment triggered a marked, immediate and reproducible alteration in community structure that persisted for the entire course of therapy and for at least 3 months following its cessation. Members of order Clostridiales were among the taxa that decreased in relative frequencies during treatment and family Porphyromonadaceae significantly increased post treatment. Experiments comparing monotherapy and different combination therapies identified rifampin as the major driver of the observed alterations induced by the HRZ cocktail but also revealed unexpected effects of isoniazid and pyrazinamide in certain drug pairings.
This report provides the first detailed analysis of the longitudinal changes in the intestinal microbiota due to anti-tuberculosis therapy. Importantly, many of the affected taxa have been previously shown in other systems to be associated with modifications in immunologic function. Together, our findings reveal that the antibiotics used in conventional TB treatment induce a distinct and long lasting dysbiosis. In addition, they establish a murine model for studying the potential impact of this dysbiosis on host resistance and physiology.
Cellular necrosis during Mycobacterium tuberculosis (Mtb) infection promotes both immunopathology and bacterial dissemination. Glutathione peroxidase-4 (Gpx4) is an enzyme that plays a critical role ...in preventing iron-dependent lipid peroxidation-mediated cell death (ferroptosis), a process previously implicated in the necrotic pathology seen in Mtb-infected mice. Here, we document altered GPX4 expression, glutathione levels, and lipid peroxidation in patients with active tuberculosis and assess the role of this pathway in mice genetically deficient in or overexpressing Gpx4. We found that Gpx4-deficient mice infected with Mtb display substantially increased lung necrosis and bacterial burdens, while transgenic mice overexpressing the enzyme show decreased bacterial loads and necrosis. Moreover, Gpx4-deficient macrophages exhibited enhanced necrosis upon Mtb infection in vitro, an outcome suppressed by the lipid peroxidation inhibitor, ferrostatin-1. These findings provide support for the role of ferroptosis in Mtb-induced necrosis and implicate the Gpx4/GSH axis as a target for host-directed therapy of tuberculosis.
Parasites of the Leishmania genus are the causative agents of leishmaniasis in humans, a disease that affects more than 12 million people worldwide. These parasites replicate intracellularly in ...macrophages, and the primary mechanisms underlying host resistance involve the production of nitric oxide (NO). In this study we show that the Nlrp3 inflammasome is activated in response to Leishmania infection and is important for the restriction of parasite replication both in macrophages and in vivo as demonstrated through the infection of inflammasome-deficient mice with Leishmania amazonensis, Leishmania braziliensis and Leishmania infantum chagasi. Inflammasome-driven interleukin-1β (IL-1β) production facilitated host resistance to infection, as signaling through IL-1 receptor (IL-1R) and MyD88 was necessary and sufficient to trigger inducible nitric oxide synthase (NOS2)-mediated production of NO. In this manuscript we identify a major signaling platform for host resistance to Leishmania spp. infection and describe the molecular mechanisms underlying Leishmania-induced NO production.
The neurohormone oxytocin is a key player in the modulation of reproductive and social behavioral traits, such as parental care. Recently, a correlation between different forms of oxytocin and ...behavioral phenotypes has been described in the New World Monkeys (NWMs). Here, we demonstrate that, compared with the Leu⁸OXT found in most placental mammals, the Cebidae Pro⁸OXT and Saguinus Val³Pro⁸OXT taxon-specific variants act as equiefficacious agonists for the Gq-dependent pathway but are weaker agonists for the β-arrestin engagement and subsequent endocytosis toward the oxytocin receptor (OXTR). Upon interaction with the AVPR1a, Pro⁸OXT and the common Leu⁸OXT yielded similar signaling profiles, being equally efficacious on Gq and β-arrestin, while Val³Pro⁸OXT showed reduced relative efficacy toward β-arrestin. Intranasal treatment with either of the variants increased maternal behavior and also promoted unusual paternal care in rats, as measured by pup-retrieval tests. We therefore suggest that Val³Pro⁸OXT and Pro⁸OXT are functional variants, which might have been evolutionarily co-opted as an essential part of the adaptive genetic repertoire that allowed the emergence of taxon-specific complex social behaviors, such as intense parental care in the Cebidae and the genus Saguinus.
Heme oxygenase-1 (HO-1) is an enzyme that catalyzes the degradation of heme, releasing equimolar amounts of carbon monoxide (CO), biliverdin (BV), and iron. The anti-inflammatory and antioxidant ...properties of HO-1 activity are conferred in part by the release of CO and BV and are extensively characterized. However, iron constitutes an important product of HO-1 activity involved in the regulation of several cellular biological processes. The macrophage-mediated recycling of heme molecules, in particular those contained in hemoglobin, constitutes the major mechanism through which living organisms acquire iron. This process is finely regulated by the activities of HO-1 and of the iron exporter protein ferroportin. The expression of both proteins can be induced or suppressed in response to pro- and anti-inflammatory stimuli in macrophages from different tissues, which alters the intracellular iron concentrations of these cells. As we discuss in this review article, changes in intracellular iron levels play important roles in the regulation of cellular oxidation reactions as well as in the transcriptional and translational regulation of the expression of proteins related to inflammation and immune responses, and therefore, iron metabolism represents a potential target for the development of novel therapeutic strategies focused on the modulation of immunity and inflammation.
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