Alteration of ß-glucan in the emerging fungal pathogen Candida auris leads to immune evasion and increased virulence.

Candida auris is an emerging pathogenic yeast that has been categorized as a global public health threat and a critical priority among fungal pathogens. Despite this, the immune response against C. auris infection is still not well understood. Hosts fight Candida infections through the immune system that recognizes pathogen-associated molecular patterns such as ß-glucan, mannan, and chitin on the fungal cell wall. In this study, levels of ß-glucan and mannan exposures in C. auris grown under different physiologically relevant stimuli were quantified by flow cytometry-based analysis. Lactate, hypoxia, and sublethal concentration of fluconazole trigger a decrease in surface ß-glucan while low pH triggers an increase in ß-glucan. There is no inverse pattern between exposure levels of ß-glucan and mannan in the cell wall architecture among the three clades. To determine the effect of cell wall remodeling on the immune response, a phagocytosis assay was performed, followed by quantification of released cytokines by ELISA. Lactate-induced decrease in ß-glucan leads to reduced uptake of C. auris by PMA-differentiated THP-1 and RAW 264.7 macrophages. Furthermore, reduced production of CCL3/MIP-1⍺ but not TNF-⍺ and IL-10 were observed. An in vivo infection analysis using silkworms reveals that a reduction in ß-glucan triggers an increase in the virulence of C. auris. This study demonstrates that ß-glucan alteration occurs in C. auris and serves as an escape mechanism from immune cells leading to increased virulence.

Evolution and host-specific adaptation of Pseudomonas aeruginosa.

The major human bacterial pathogen Pseudomonas aeruginosa causes multidrug-resistant infections in people with underlying immunodeficiencies or structural lung diseases such as cystic fibrosis (CF). We show that a few environmental isolates, driven by horizontal gene acquisition, have become dominant epidemic clones that have sequentially emerged and spread through global transmission networks over the past 200 years. These clones demonstrate varying intrinsic propensities for infecting CF or non-CF individuals (linked to specific transcriptional changes enabling survival within macrophages); have undergone multiple rounds of convergent, host-specific adaptation; and have eventually lost their ability to transmit between different patient groups. Our findings thus explain the pathogenic evolution of P. aeruginosa and highlight the importance of global surveillance and cross-infection prevention in averting the emergence of future epidemic clones.

Overexpression of LAG-3: a potential indicator of low immune function in tuberculosis.

Background: Tuberculosis (TB) persists as a global health challenge, with its treatment hampered by the side effects of long-term combination drug therapies and the growing issue of drug resistance. Therefore, the development of novel therapeutic strategies is critical. This study focuses on the role of immune checkpoint molecules (ICs) and functions of CD8+ T cells in the search for new potential targets against TB. Methods: We conducted differential expression genes analysis and CD8+ T cell functional gene analysis on 92 TB samples and 61 healthy individual (HI) samples from TB database GSE83456, which contains data on 34,603 genes. The GSE54992 dataset was used to validated the findings. Additionally, a cluster analysis on single-cell data from primates infected with mycobacterium tuberculosis and those vaccinated with BCG was performed. Results: The overexpression of LAG-3 gene was found as a potentially important characteristic of both pulmonary TB (PTB) and extrapulmonary TB (EPTB). Further correlation analysis showed that LAG-3 gene was correlated with GZMB, perforin, IL-2 and IL-12. A significant temporal and spatial variation in LAG-3 expression was observed in T cells and macrophages during TB infection and after BCG vaccination. Conclusion: LAG-3 was overexpressed in TB samples. Targeting LAG-3 may represent a potential therapeutic target for tuberculosis.

Small Molecule Targeting PPM1A Activates Autophagy for Mycobacterium tuberculosis Host-Directed Therapy.

Mycobacterium tuberculosis (Mtb), the infectious agent of tuberculosis (TB), causes over 1.5 million deaths globally every year. Host-directed therapies (HDT) for TB are desirable for their potential to shorten treatment and reduce the development of antibiotic resistance. Previously, we described a modular biomimetic strategy to identify SMIP-30, targeting PPM1A (IC50 = 1.19 µM), a metal-dependent phosphatase exploited by Mtb to survive intracellularly. SMIP-30 restricted the survival of Mtb in macrophages and lungs of infected mice. Herein, we redesigned SMIP-30 to create SMIP-031, which is a more potent inhibitor for PPM1A (IC50 = 180 nM). SMIP-031 efficiently increased the level of phosphorylation of S403-p62 and the expression of LC3B-II to activate autophagy, resulting in the dose-dependent clearance of Mtb in infected macrophages. SMIP-031 possesses a good pharmacokinetic profile and oral bioavailability (F = 74%). In vivo, SMIP-031 is well tolerated up to 50 mg/kg and significantly reduces the bacteria burden in the spleens of infected mice.

Desaminotyrosine is a redox-active microbial metabolite that bolsters macrophage antimicrobial functions while attenuating IL-6 production.

Intestinal microbiota contributes to host defense against pathogens while avoiding the induction of inflammation in homeostatic conditions, but the mechanism is not fully understood. To investigate the potential role of the bacterial metabolite desaminotyrosine (DAT) in regulating host defense and inflammation, we pretreated mouse bone marrow-derived macrophages (BMDMs) with DAT for 12 hours and then challenged with bacterial lipopolysaccharide (LPS). We found that DAT priming-enhanced type I interferon response while selectively inhibiting proinflammatory interleukin (IL)-6 production after exposure to LPS. This is related to the fact that DAT is a natural antioxidant determined by radical scavenging assay in a cell-free system. DAT-primed cells had increased levels of the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) upon LPS stimulation. Countering the increased NADPH by supplementing extra oxidized NADP+ to cells reversed DAT's effect on LPS-induced Il-6 and interferon-stimulated gene expressions. DAT-primed cells also were more resistant to oxidative stress-induced generation of reactive oxygen species and cell death. DAT promoted the production of antimicrobial effector nitric oxide in a cellular redox-dependent manner, leading to enhanced macrophage antimicrobial activity during Salmonella enterica infection. Our data suggest that DAT acts as a host-microbiota crosstalk signal in shaping host immune defense and inflammatory response.

CRIg+ macrophages deficiency enhanced inflammation damage in IBD due to gut extracellular vesicles containing microbial DNA.

Gut microbiota-derived extracellular vesicles (mEVs) are reported to regulate inflammatory response by delivering bacterial products into host cells. The complement receptor of the immunoglobulin superfamily macrophages (CRIg+ Mφ) could clear invading bacteria and their derivatives. Here, we investigate the role of CRIg+ Mφ and the mechanism by which mEVs regulate intestinal inflammation. We found that it is exacerbated in IBD patients and colitis mice by mEVs' leakage from disturbed gut microbiota, enriching microbial DNA in the intestinal mucosa. CRIg+ Mφ significantly decrease in IBD patients, allowing the spread of mEVs into the mucosa. The microbial DNA within mEVs is the key trigger for inflammation and barrier function damage. The cGAS/STING pathway is crucial in mEVs-mediated inflammatory injury. Blocking cGAS/STING signaling effectively alleviates inflammation caused by mEVs leakage and CRIg+ Mφ deficiency. Microbial DNA-containing mEVs, along with CRIg+ Mφ deficiency, stimulate inflammation in IBD, with the cGAS/STING pathway playing a crucial role.

Roles of Critical Amino Acids Metabolism in The Interactions Between Intracellular Bacterial Infection and Macrophage Function.

Macrophages, as crucial participants in the innate immune system, respond to pathogenic challenges through their dynamic metabolic adjustments, demonstrating the intimate interplay between cellular metabolism and immune function. Bacterial infection of macrophages causes changes in macrophage metabolism, affecting both macrophage function and bacterial virulence and intracellular survival. This review explores the reprogramming of amino acid metabolism in macrophages in response to bacterial infection, with a particular focus on the influence of critical amino acids such as serine, glutamine, and arginine on the immune functions of macrophages; highlights the roles of these metabolic pathways in macrophage functions such as phagocytosis, inflammatory response, immune regulation, and pathogen clearance; reveals how pathogens exploit and manipulate the amino acid metabolism within macrophages to support their own growth and replication, thereby showcasing the intricate interplay between macrophages and pathogens. It provides a foundation for understanding the interactions between macrophages amino acid metabolism and pathogens, offering potential strategies and therapeutic targets for the development of novel anti-infection therapies.

Unraveling host-pathogen dynamics in a murine Model of septic peritonitis induced by vancomycin-resistant Enterococcus faecium.

Vancomycin-resistant Enterococcus faecium (E. faecium) infection is associated with higher mortality rates. Previous studies have emphasized the importance of innate immune cells and signalling pathways in clearing E. faecium, but a comprehensive analysis of host-pathogen interactions is lacking. Here, we investigated the interplay of host and E. faecium in a murine model of septic peritonitis. Following injection with a sublethal dose, we observed significantly increased murine sepsis score and histological score, decreased weight and bacterial burden, neutrophils and macrophages infiltration, and comprehensive activation of cytokine-mediated signalling pathway. In mice receiving a lethal dose, hypothermia significantly improved survival, reduced bacterial burden, cytokines, and CD86 expression of MHC-II+ recruited macrophages compared to the normothermia group. A mathematical model constructed by observational data from 80 animals, recapitulated the host-pathogen interplay, and further verified the benefits of hypothermia. These findings indicate that E. faecium triggers a severe activation of cytokine-mediated signalling pathway, and hypothermia can improve outcomes by reducing bacterial burden and inflammation.

The role of cytolethal distending toxin in Glaesserella parasuis JS0135 strain infection: Cytotoxicity, phagocytic resistance and pathogenicity.

Glaesserella parasuis is an important porcine pathogen that commonly colonizes the upper respiratory tract of pigs and is prone to causing Glässer's disease under complex conditions. As yet, the disease has led to serious economic losses to the swine industry worldwide. Studies so far have found that several virulence factors are associated with the pathogenicity of G. parasuis, but the pathogenic mechanism is still not fully understood. Cytolethal distending toxin (CDT), a potential virulence factor in G. parasuis, is involved in cytotoxicity, serum resistance, adherence to and invasion of host cells in vitro. Here, to further investigate the pathogenic role of CDT during G. parasuis infection in vitro and in vivo, a double cdt1 and cdt2 deletion mutant (Δcdt1Δcdt2) without selectable marker was first generated in G. parasuis JS0135 strain by continuous natural transformations and replica plating. Morphological observation and lactate dehydrogenase assay showed that the Δcdt1Δcdt2 mutant was defective in cytotoxicity. Additionally, the Δcdt1Δcdt2 mutant was more susceptible to phagocytosis caused by 3D4/2 macrophages compared to the wild-type JS0135 strain. Moreover, by focusing on clinical signs, necropsy, bacterial recovery and pathological observation, we found that the deletion of cdt1 and cdt2 genes led to a significant attenuation of virulence in G. parasuis. Taken together, these findings suggest that as an important virulence factor, CDT can significantly affect the pathogenicity of G. parasuis.

Exploring the potential of Lactocaseibacillus rhamnosus PMC203 in inducing autophagy to reduce the burden of Mycobacterium tuberculosis.

Mycobacterium tuberculosis, a lethal pathogen in human history, causes millions of deaths annually, which demands the development of new concepts of drugs. Considering this fact, earlier research has explored the anti-tuberculosis potential of a probiotic strain, Lactocaseibacillus rhamnosus PMC203, leading to a subsequent focus on the molecular mechanism involved in its effect, particularly on autophagy. In this current study, immunoblotting-based assay exhibited a remarkable expression of autophagy marker LC3-II in the PMC203 treated group compared to an untreated group. A remarkable degradation of p62 was also noticed within treated cells compared to control. Furthermore, the immunofluorescence-based assay showed significant fold change in fluorescence intensity for alexa-647-LC3 and alexa-488-LC3, whereas p62 was degraded noticeably. Moreover, lysosomal biogenesis generation was elevated significantly in terms of LAMP1 and acidic vesicular organelles. As a result, PMC203-induced autophagy played a vital role in reducing M. tuberculosis burden within the macrophages in treated groups compared to untreated group. A colony -forming unit assay also revealed a significant reduction in M. tuberculosis in the treated cells over time. Additionally, the candidate strain significantly upregulated the expression of autophagy induction and lysosomal biogenesis genes. Together, these results could enrich our current knowledge of probiotics-mediated autophagy in tuberculosis and suggest its implications for innovatively managing tuberculosis.

CircCDC42-encoded CDC42-165aa regulates macrophage pyroptosis in Klebsiella pneumoniae infection through Pyrin inflammasome activation.

The circular RNA (circRNA) family is a group of endogenous non-coding RNAs (ncRNAs) that have critical functions in multiple physiological and pathological processes, including inflammation, cancer, and cardiovascular diseases. However, their roles in regulating innate immune responses remain unclear. Here, we define Cell division cycle 42 (CDC42)-165aa, a protein encoded by circRNA circCDC42, which is overexpressed in Klebsiella pneumoniae (KP)-infected alveolar macrophages. High levels of CDC42-165aa induces the hyperactivation of Pyrin inflammasomes and aggravates alveolar macrophage pyroptosis, while the inhibition of CDC42-165aa reduces lung injury in mice after KP infection by inhibiting Pyrin inflammasome-mediated pyroptosis. Overall, these results demonstrate that CDC42-165aa stimulates Pyrin inflammasome by inhibiting CDC42 GTPase activation and provides a potential clinical target for pathogenic bacterial infection in clinical practice.

Beyond its preferential niche: Brucella abortus RNA down-modulates the IFN-γ-induced MHC-I expression in epithelial and endothelial cells.

Brucella abortus (Ba) is a pathogen that survives inside macrophages. Despite being its preferential niche, Ba infects other cells, as shown by the multiple signs and symptoms humans present. This pathogen can evade our immune system. Ba displays a mechanism of down-modulating MHC-I on monocytes/macrophages in the presence of IFN-γ (when Th1 response is triggered) without altering the total expression of MHC-I. The retained MHC-I proteins are located within the Golgi Apparatus (GA). The RNA of Ba is one of the PAMPs that trigger this phenomenon. However, we acknowledged whether this event could be triggered in other cells relevant during Ba infection. Here, we demonstrate that Ba RNA reduced the surface expression of MHC-I induced by IFN-γ in the human bronchial epithelium (Calu-6), the human alveolar epithelium (A-549) and the endothelial microvasculature (HMEC) cell lines. In Calu-6 and HMEC cells, Ba RNA induces the retention of MHC-I in the GA. This phenomenon was not observed in A-549 cells. We then evaluated the effect of Ba RNA on the secretion of IL-8, IL-6 and MCP-1, key cytokines in Ba infection. Contrary to our expectations, HMEC, Calu-6 and A-549 cells treated with Ba RNA had higher IL-8 and IL-6 levels compared to untreated cells. In addition, we showed that Ba RNA down-modulates the MHC-I surface expression induced by IFN-γ on human monocytes/macrophages via the pathway of the Epidermal Growth Factor Receptor (EGFR). So, cells were stimulated with an EGFR ligand-blocking antibody (Cetuximab) and Ba RNA. Neutralization of the EGFR to some extent reversed the down-modulation of MHC-I mediated by Ba RNA in HMEC and A-549 cells. In conclusion, this is the first study exploring a central immune evasion strategy, such as the downregulation of MHC-I surface expression, beyond monocytes and could shed light on how it persists effectively within the host, enduring unseen and escaping CD8+ T cell surveillance.

Molecular definition of the endogenous Toll-like receptor signalling pathways.

Innate immune pattern recognition receptors, such as the Toll-like receptors (TLRs), are key mediators of the immune response to infection and central to our understanding of health and disease1. After microbial detection, these receptors activate inflammatory signal transduction pathways that involve IκB kinases, mitogen-activated protein kinases, ubiquitin ligases and other adaptor proteins. The mechanisms that connect the proteins in the TLR pathways are poorly defined. To delineate TLR pathway activities, we engineered macrophages to enable microscopy and proteomic analysis of the endogenous myddosome constituent MyD88. We found that myddosomes form transient contacts with activated TLRs and that TLR-free myddosomes are dynamic in size, number and composition over the course of 24 h. Analysis using super-resolution microscopy revealed that, within most myddosomes, MyD88 forms barrel-like structures that function as scaffolds for effector protein recruitment. Proteomic analysis demonstrated that myddosomes contain proteins that act at all stages and regulate all effector responses of the TLR pathways, and genetic analysis defined the epistatic relationship between these effector modules. Myddosome assembly was evident in cells infected with Listeria monocytogenes, but these bacteria evaded myddosome assembly and TLR signalling during cell-to-cell spread. On the basis of these findings, we propose that the entire TLR signalling pathway is executed from within the myddosome.

Heterogeneity in lung macrophage control of Mycobacterium tuberculosis is modulated by T cells.

Following Mycobacterium tuberculosis infection, alveolar macrophages are initially infected but ineffectively restrict bacterial replication. The distribution of M. tuberculosis among different cell types in the lung changes with the onset of T cell immunity when the dominant infected cellular niche shifts from alveolar to monocyte-derived macrophages (MDM). We hypothesize that changes in bacterial distribution among different cell types is driven by differences in T cell recognition of infected cells and their subsequent activation of antimicrobial effector mechanisms. We show that CD4 and CD8 T cells efficiently eliminate M. tuberculosis infection in alveolar macrophages, but they have less impact on suppressing infection in MDM, which may be a bacterial niche. Importantly, CD4 T cell responses enhance MDM recruitment to the lung. Thus, the outcome of infection depends on the interaction between the T cell subset and the infected cell; both contribute to the resolution and persistence of the infection.

The mycobacterial glycoside hydrolase LamH enables capsular arabinomannan release and stimulates growth.

Mycobacterial glycolipids are important cell envelope structures that drive host-pathogen interactions. Arguably, the most important are lipoarabinomannan (LAM) and its precursor, lipomannan (LM), which are trafficked from the bacterium to the host via unknown mechanisms. Arabinomannan is thought to be a capsular derivative of these molecules, lacking a lipid anchor. However, the mechanism by which this material is generated has yet to be elucidated. Here, we describe the identification of a glycoside hydrolase family 76 enzyme that we term LamH (Rv0365c in Mycobacterium tuberculosis) which specifically cleaves α-1,6-mannoside linkages within LM and LAM, driving its export to the capsule releasing its phosphatidyl-myo-inositol mannoside lipid anchor. Unexpectedly, we found that the catalytic activity of this enzyme is important for efficient exit from stationary phase cultures, potentially implicating arabinomannan as a signal for growth phase transition. Finally, we demonstrate that LamH is important for M. tuberculosis survival in macrophages.

Clinical and in vitro models identify distinct adaptations enhancing Staphylococcus aureus pathogenesis in human macrophages.

Staphylococcus aureus is a facultative intracellular pathogen of human macrophages, which facilitates chronic infection. The genotypes, pathways, and mutations influencing that phenotype remain incompletely explored. Here, we used two distinct strategies to ascertain S. aureus gene mutations affecting pathogenesis in macrophages. First, we analyzed isolates collected serially from chronic cystic fibrosis (CF) respiratory infections. We found that S. aureus strains evolved greater macrophage invasion capacity during chronic human infection. Bacterial genome-wide association studies (GWAS) identified 127 candidate genes for which mutation was significantly associated with macrophage pathogenesis in vivo. In parallel, we passaged laboratory S. aureus strains in vitro to select for increased infection of human THP-1 derived macrophages, which identified 15 candidate genes by whole-genome sequencing. Functional validation of candidate genes using isogenic transposon mutant knockouts and CRISPR interference (CRISPRi) knockdowns confirmed virulence contributions from 37 of 39 tested genes (95%) implicated by in vivo studies and 7 of 10 genes (70%) ascertained from in vitro selection, with one gene in common to the two strategies. Validated genes included 17 known virulence factors (39%) and 27 newly identified by our study (61%), some encoding functions not previously associated with macrophage pathogenesis. Most genes (80%) positively impacted macrophage invasion when disrupted, consistent with the phenotype readily arising from loss-of-function mutations in vivo. This work reveals genes and mechanisms that contribute to S. aureus infection of macrophages, highlights differences in mutations underlying convergent phenotypes arising from in vivo and in vitro systems, and supports the relevance of S. aureus macrophage pathogenesis during chronic respiratory infection in CF. Additional studies will be needed to illuminate the exact mechanisms by which implicated mutations affect their phenotypes.

Lysozyme: an endogenous antimicrobial protein with potent activity against extracellular, but not intracellular Mycobacterium tuberculosis.

Endogenous antimicrobial peptides (AMPs) play a key role in the host defense against pathogens. AMPs attack pathogens preferentially at the site of entry to prevent invasive infection. Mycobacterium tuberculosis (Mtb) enters its host via the airways. AMPs released into the airways are therefore likely candidates to contribute to the clearance of Mtb immediately after infection. Since lysozyme is detectable in airway secretions, we evaluated its antimicrobial activity against Mtb. We demonstrate that lysozyme inhibits the growth of extracellular Mtb, including isoniazid-resistant strains. Lysozyme also inhibited the growth of non-tuberculous mycobacteria. Even though lysozyme entered Mtb-infected human macrophages and co-localized with the pathogen we did not observe antimicrobial activity. This observation was unlikely related to the large size of lysozyme (14.74 kDa) because a smaller lysozyme-derived peptide also co-localized with Mtb without affecting the viability. To evaluate whether the activity of lysozyme against extracellular Mtb could be relevant in vivo, we incubated Mtb with fractions of human serum and screened for antimicrobial activity. After several rounds of sub-fractionation, we identified a highly active fraction-component as lysozyme by mass spectrometry. In summary, our results identify lysozyme as an antimycobacterial protein that is detectable as an active compound in human serum. Our results demonstrate that the activity of AMPs against extracellular bacilli does not predict efficacy against intracellular pathogens despite co-localization within the macrophage. Ongoing experiments are designed to unravel peptide modifications that occur in the intracellular space and interfere with the deleterious activity of lysozyme in the extracellular environment.

Integrative analysis of single-cell RNA-seq and gut microbiome metabarcoding data elucidates macrophage dysfunction in mice with DSS-induced ulcerative colitis.

Ulcerative colitis (UC) is a significant inflammatory bowel disease caused by an abnormal immune response to gut microbes. However, there are still gaps in our understanding of how immune and metabolic changes specifically contribute to this disease. Our research aims to address this gap by examining mouse colons after inducing ulcerative colitis-like symptoms. Employing single-cell RNA-seq and 16 s rRNA amplicon sequencing to analyze distinct cell clusters and microbiomes in the mouse colon at different time points after induction with dextran sodium sulfate. We observe a significant reduction in epithelial populations during acute colitis, indicating tissue damage, with a partial recovery observed in chronic inflammation. Analyses of cell-cell interactions demonstrate shifts in networking patterns among different cell types during disease progression. Notably, macrophage phenotypes exhibit diversity, with a pronounced polarization towards the pro-inflammatory M1 phenotype in chronic conditions, suggesting the role of macrophage heterogeneity in disease severity. Increased expression of Nampt and NOX2 complex subunits in chronic UC macrophages contributes to the inflammatory processes. The chronic UC microbiome exhibits reduced taxonomic diversity compared to healthy conditions and acute UC. The study also highlights the role of T cell differentiation in the context of dysbiosis and its implications in colitis progression, emphasizing the need for targeted interventions to modulate the inflammatory response and immune balance in colitis.

Macrophage-derived CD36 + exosome subpopulations as novel biomarkers of Candida albicans infection.

Invasive candidiasis (IC) is a notable healthcare-associated fungal infection, characterized by high morbidity, mortality, and substantial treatment costs. Candida albicans emerges as a principal pathogen in this context. Recent academic advancements have shed light on the critical role of exosomes in key biological processes, such as immune responses and antigen presentation. This burgeoning body of research underscores the potential of exosomes in the realm of medical diagnostics and therapeutics, particularly in relation to fungal infections like IC. The exploration of exosomal functions in the pathophysiology of IC not only enhances our understanding of the disease but also opens new avenues for innovative therapeutic interventions. In this investigation, we focus on exosomes (Exos) secreted by macrophages, both uninfected and those infected with C. albicans. Our objective is to extract and analyze these exosomes, delving into the nuances of their protein compositions and subgroups. To achieve this, we employ an innovative technique known as Proximity Barcoding Assay (PBA). This methodology is pivotal in our quest to identify novel biological targets, which could significantly enhance the diagnostic and therapeutic approaches for C. albicans infection. The comparative analysis of exosomal contents from these two distinct cellular states promises to yield insightful data, potentially leading to breakthroughs in understanding and treating this invasive fungal infection. In our study, we analyzed differentially expressed proteins in exosomes from macrophages and C. albicans -infected macrophages, focusing on proteins such as ACE2, CD36, CAV1, LAMP2, CD27, and MPO. We also examined exosome subpopulations, finding a dominant expression of MPO in the most prevalent subgroup, and a distinct expression of CD36 in cluster14. These findings are crucial for understanding the host response to C. albicans and may inform targeted diagnostic and therapeutic approaches. Our study leads us to infer that MPO and CD36 proteins may play roles in the immune escape mechanisms of C. albicans. Additionally, the CD36 exosome subpopulations, identified through our analysis, could serve as potential biomarkers and therapeutic targets for C. albicans infection. This insight opens new avenues for understanding the infection's pathology and developing targeted treatments.

Tribbles1 is host protective during in vivo mycobacterial infection.

Tuberculosis is a major global health problem and is one of the top 10 causes of death worldwide. There is a pressing need for new treatments that circumvent emerging antibiotic resistance. Mycobacterium tuberculosis parasitises macrophages, reprogramming them to establish a niche in which to proliferate, therefore macrophage manipulation is a potential host-directed therapy if druggable molecular targets could be identified. The pseudokinase Tribbles1 (Trib1) regulates multiple innate immune processes and inflammatory profiles making it a potential drug target in infections. Trib1 controls macrophage function, cytokine production, and macrophage polarisation. Despite wide-ranging effects on leukocyte biology, data exploring the roles of Tribbles in infection in vivo are limited. Here, we identify that human Tribbles1 is expressed in monocytes and is upregulated at the transcript level after stimulation with mycobacterial antigen. To investigate the mechanistic roles of Tribbles in the host response to mycobacteria in vivo, we used a zebrafish Mycobacterium marinum (Mm) infection tuberculosis model. Zebrafish Tribbles family members were characterised and shown to have substantial mRNA and protein sequence homology to their human orthologues. trib1 overexpression was host-protective against Mm infection, reducing burden by approximately 50%. Conversely, trib1 knockdown/knockout exhibited increased infection. Mechanistically, trib1 overexpression significantly increased the levels of proinflammatory factors il-1ß and nitric oxide. The host-protective effect of trib1 was found to be dependent on the E3 ubiquitin kinase Cop1. These findings highlight the importance of Trib1 and Cop1 as immune regulators during infection in vivo and suggest that enhancing macrophage TRIB1 levels may provide a tractable therapeutic intervention to improve bacterial infection outcomes in tuberculosis.