Phenolic Glycolipid Facilitates Mycobacterial Escape from Microbicidal Tissue-Resident Macrophages

Mycobacterium tuberculosis (Mtb) enters the host in aerosol droplets deposited in lung alveoli, where the bacteria first encounter lung-resident alveolar macrophages. We studied the earliest mycobacterium-macrophage interactions in the optically transparent zebrafish. First-responding resident macrophages phagocytosed and eradicated infecting mycobacteria, suggesting that to establish a successful infection, mycobacteria must escape out of the initially infected resident macrophage into growth-permissive monocytes. We defined a critical role for mycobacterial membrane phenolic glycolipid (PGL) in engineering this transition. PGL activated the STING cytosolic sensing pathway in resident macrophages, inducing the production of the chemokine CCL2, which in turn recruited circulating CCR2+ monocytes towards infection. Transient fusion of infected macrophages with CCR2+ monocytes enabled bacterial transfer and subsequent dissemination, and interrupting this transfer so as to prolong mycobacterial sojourn in resident macrophages promoted clearing of infection. Human alveolar macrophages produced CCL2 upon Mtb infection, arguing for the potential of PGL-blocking interventions or PGL-targeting vaccine strategies in the prevention of tuberculosis.This work was supported by the NIH Director’s Pioneer Award, NIH grant R37AI054503, and a Wellcome Trust Principal Research Fellowship (L.R.), NIH training grant T32 AI55396 and a Damon Runyon Postdoctoral Fellowship (C.J.C.), the Health Research Board of Ireland (S.M.O., M.P.O., and J.K.), and The Royal City of Dublin Hospital Trust (J.K.)

Lysosomal Disorders Drive Susceptibility to Tuberculosis by Compromising Macrophage Migration.

A zebrafish genetic screen for determinants of susceptibility to Mycobacterium marinum identified a hypersusceptible mutant deficient in lysosomal cysteine cathepsins that manifests hallmarks of human lysosomal storage diseases. Under homeostatic conditions, mutant macrophages accumulate undigested lysosomal material, which disrupts endocytic recycling and impairs their migration to, and thus engulfment of, dying cells. This causes a buildup of unengulfed cell debris. During mycobacterial infection, macrophages with lysosomal storage cannot migrate toward infected macrophages undergoing apoptosis in the tuberculous granuloma. The unengulfed apoptotic macrophages undergo secondary necrosis, causing granuloma breakdown and increased mycobacterial growth. Macrophage lysosomal storage similarly impairs migration to newly infecting mycobacteria. This phenotype is recapitulated in human smokers, who are at increased risk for tuberculosis. A majority of their alveolar macrophages exhibit lysosomal accumulations of tobacco smoke particulates and do not migrate to Mycobacterium tuberculosis. The incapacitation of highly microbicidal first-responding macrophages may contribute to smokers' susceptibility to tuberculosis.This work was supported by the National Institutes of Health (R37AI054503, LR, R01NS082567, CBM, 5F30HL110455, RB, 1DP2-OD008614, DMT), the Wellcome Trust (LR), the National Institute of Health Research Cambridge Biomedical Research Centre (LR), the Health Research Board of Ireland (HRA_POR/2013/387, MO’S and CSA/2012/16, JK), and The Royal City of Dublin Hospital Trust (Grant 146, JK).This is the final version of the article. It first appeared from Cell Press via http://dx.doi.org/10.1016/j.cell.2016.02.034

A Macrophage Response to Mycobacterium leprae Phenolic Glycolipid Initiates Nerve Damage in Leprosy

$\textit{Mycobacterium leprae}$ causes leprosy and is unique among mycobacterial diseases in producing peripheral neuropathy. This debilitating morbidity is attributed to axon demyelination resulting from direct interaction of the $\textit{M. leprae}$-specific phenolic glycolipid 1 (PGL-1) with myelinating glia and their subsequent infection. Here, we use transparent zebrafish larvae to visualize the earliest events of $\textit{M. leprae}$-induced nerve damage. We find that demyelination and axonal damage are not directly initiated by $\textit{M. leprae}$ but by infected macrophages that patrol axons; demyelination occurs in areas of intimate contact. PGL-1 confers this neurotoxic response on macrophages: macrophages infected with $\textit{M. marinum}$-expressing PGL-1 also damage axons. PGL-1 induces nitric oxide synthase in infected macrophages, and the resultant increase in reactive nitrogen species damages axons by injuring their mitochondria and inducing demyelination. Our findings implicate the response of innate macrophages to $\textit{M. leprae}$ PGL-1 in initiating nerve damage in leprosy.This work was supported by an A.P. Giannini Foundation Postdoctoral Fellowship, an NIH training grant (T32 AI1007411), and an NIH NRSA Postdoctoral Fellowship (AI104240) to C.A.M.; an NSF Predoctoral Fellowship and NIH training grant T32 AI55396 to C.J.C.; a UCLA Clinical Translational Science Institute grant (UL1TR001881 to K.K.S.); K08AR066545 to P.O.S.; U19AI111224 and R01AI049313 to D.B.M.; an NIH grant (R01AR064582) to A.S.; the NIH Director’s Pioneer Award, an NIH MERIT award (R37AI054503), and a Wellcome Trust Principal Research Fellowship to L.R

Tuberculosis is associated with expansion of a motile, permissive and immunomodulatory CD16(+) monocyte population via the IL-10/STAT3 axis

The human CD14+ monocyte compartment is composed by two subsets based on CD16 expression. We previously reported that this compartment is perturbed in tuberculosis (TB) patients, as reflected by the expansion of CD16+ monocytes along with disease severity. Whether this unbalance is beneficial or detrimental to host defense remains to be elucidated. Here in the context of active TB, we demonstrate that human monocytes are predisposed to differentiate towards an anti-inflammatory (M2-like) macrophage activation program characterized by theCD16+CD163+MerTK+pSTAT3+ phenotype and functional properties such as enhanced protease-dependent motility, pathogen permissivity and immunomodulation. This process is dependent on STAT3 activation, and loss-of-function experiments point towards a detrimental role in host defense against TB. Importantly, we provide a critical correlation between the abundance of the CD16+CD163+MerTK+pSTAT3+ cells and the progression of the disease either at the local level in a non-human primate tuberculous granuloma context, or at the systemic level through the detection of the soluble form of CD163 in human sera. Collectively, this study argues for the pathogenic role of the CD16+CD163+MerTK+pSTAT3+ monocyte-to-macrophage differentiation program and its potential as a target for TB therapy,and promotes the detection of circulating CD163 as a potential biomarker for disease progression and monitoringof treatment efficacy.Fil: Lastrucci, Claire. Centre National de la Recherche Scientifique; FranciaFil: Bénard, Alan. Centre National de la Recherche Scientifique; FranciaFil: Balboa, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Pingris, Karine. Centre National de la Recherche Scientifique; FranciaFil: Souriant, Shanti. Centre National de la Recherche Scientifique; FranciaFil: Poincloux, Renaud. Centre National de la Recherche Scientifique; FranciaFil: Al Saati, Talal. Inserm; FranciaFil: Rasolofo, Voahangy. Pasteur Institute in Antananarivo; MadagascarFil: González Montaner, Pablo. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas ; ArgentinaFil: Inwentarz, Sandra. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas ; ArgentinaFil: Moraña, Eduardo José. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas ; ArgentinaFil: Kondova, Ivanela. Biomedical Primate Research Centre; Países BajosFil: Verreck, Franck A. W.. Biomedical Primate Research Centre; Países BajosFil: Sasiain, María del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Neyrolles, Olivier. Centre National de la Recherche Scientifique; FranciaFil: Maridonneau Parini, Isabel. Centre National de la Recherche Scientifique; FranciaFil: Lugo Villarino, Geanncarlo. Centre National de la Recherche Scientifique; FranciaFil: Cougoule, Celine. Centre National de la Recherche Scientifique; Franci

In vivo biomolecular imaging of zebrafish embryos using confocal Raman spectroscopy

Zebrafish embryos provide a unique opportunity to visualize complex biological processes, yet conventional imaging modalities are unable to access intricate biomolecular information without compromising the integrity of the embryos. Here, we report the use of confocal Raman spectroscopic imaging for the visualization and multivariate analysis of biomolecular information extracted from unlabeled zebrafish embryos. We outline broad applications of this method in: (i) visualizing the biomolecular distribution of whole embryos in three dimensions, (ii) resolving anatomical features at subcellular spatial resolution, (iii) biomolecular profiling and discrimination of wild type and ΔRD1 mutant Mycobacterium marinum strains in a zebrafish embryo model of tuberculosis and (iv) in vivo temporal monitoring of the wound response in living zebrafish embryos. Overall, this study demonstrates the application of confocal Raman spectroscopic imaging for the comparative bimolecular analysis of fully intact and living zebrafish embryos

Bcr/Abl Interferes with the Fanconi Anemia/BRCA Pathway: Implications in the Chromosomal Instability of Chronic Myeloid Leukemia Cells

Chronic myeloid leukemia (CML) is a malignant clonal disorder of the hematopoietic system caused by the expression of the BCR/ABL fusion oncogene. Although it is well known that CML cells are genetically unstable, the mechanisms accounting for this genomic instability are still poorly understood. Because the Fanconi anemia (FA) pathway is believed to control several mechanisms of DNA repair, we investigated whether this pathway was disrupted in CML cells. Our data show that CML cells have a defective capacity to generate FANCD2 nuclear foci, either in dividing cells or after DNA damage. Similarly, human cord blood CD34+ cells transduced with BCR/ABL retroviral vectors showed impaired FANCD2 foci formation, whereas FANCD2 monoubiquitination in these cells was unaffected. Soon after the transduction of CD34+ cells with BCR/ABL retroviral vectors a high proportion of cells with supernumerary centrosomes was observed. Similarly, BCR/ABL induced a high proportion of chromosomal abnormalities, while mediated a cell survival advantage after exposure to DNA cross-linking agents. Significantly, both the impaired formation of FANCD2 nuclear foci, and also the predisposition of BCR/ABL cells to develop centrosomal and chromosomal aberrations were reverted by the ectopic expression of BRCA1. Taken together, our data show for the first time a disruption of the FA/BRCA pathway in BCR/ABL cells, suggesting that this defective pathway should play an important role in the genomic instability of CML by the co-occurrence of centrosomal amplification and DNA repair deficiencies

Deficiency in the autophagy modulator Dram1 exacerbates pyroptotic cell death of Mycobacteria-infected macrophages

DNA damage regulated autophagy modulator 1 (DRAM1) is a stress-inducible regulator of autophagy and cell death. DRAM1 has been implicated in cancer, myocardial infarction, and infectious diseases, but the molecular and cellular functions of this transmembrane protein remain poorly understood. Previously, we have proposed DRAM1 as a host resistance factor for tuberculosis (TB) and a potential target for host-directed anti-infective therapies. In this study, we generated a zebrafish dram1 mutant and investigated its loss-of-function effects during Mycobacterium marinum (Mm) infection, a widely used model in TB research. In agreement with previous knockdown analysis, dram1 mutation increased the susceptibility of zebrafish larvae to Mm infection. RNA sequencing revealed major effects of Dram1 deficiency on metabolic, immune response, and cell death pathways during Mm infection, and only minor effects on proteinase and metabolic pathways were found under uninfected conditions. Furthermore, unchallenged dram1 mutants did not display overt autophagic defects, but autophagic targeting of Mm was reduced in the absence of Dram1. The phagocytic ability of macrophages in dram1 mutants was unaffected, but acidification of Mm-containing vesicles was strongly reduced, indicating that Dram1 is required for phagosome maturation. By in vivo imaging, we observed that Dram1-deficient macrophages fail to restrict Mm during early stages of infection. The resulting increase in bacterial burden could be reverted by knockdown of inflammatory caspase a (caspa) and gasdermin Eb (gsdmeb), demonstrating pyroptosis as the mechanism underlying premature cell death of Mm-infected macrophages in dram1 mutants. Collectively, these data demonstrate that dissemination of mycobacterial infection in zebrafish larvae is promoted in the absence of Dram1 due to reduced maturation of mycobacteria-containing vesicles, failed intracellular containment, and consequent pyroptotic death of infected macrophages. These results provide new evidence that Dram1 plays a central role in host resistance to intracellular infection, acting at the crossroad of autophagy and cell death

Childhood tuberculosis is associated with decreased abundance of T cell gene transcripts and impaired T cell function

The WHO estimates around a million children contract tuberculosis (TB) annually with over 80 000 deaths from dissemination of infection outside of the lungs. The insidious onset and association with skin test anergy suggests failure of the immune system to both recognise and respond to infection. To understand the immune mechanisms, we studied genome-wide whole blood RNA expression in children with TB meningitis (TBM). Findings were validated in a second cohort of children with TBM and pulmonary TB (PTB), and functional T-cell responses studied in a third cohort of children with TBM, other extrapulmonary TB (EPTB) and PTB. The predominant RNA transcriptional response in children with TBM was decreased abundance of multiple genes, with 140/204 (68%) of all differentially regulated genes showing reduced abundance compared to healthy controls. Findings were validated in a second cohort with concordance of the direction of differential expression in both TBM (r2 = 0.78 p = 2x10-16) and PTB patients (r2 = 0.71 p = 2x10-16) when compared to a second group of healthy controls. Although the direction of expression of these significant genes was similar in the PTB patients, the magnitude of differential transcript abundance was less in PTB than in TBM. The majority of genes were involved in activation of leucocytes (p = 2.67E-11) and T-cell receptor signalling (p = 6.56E-07). Less abundant gene expression in immune cells was associated with a functional defect in T-cell proliferation that recovered after full TB treatment (p<0.0003). Multiple genes involved in T-cell activation show decreased abundance in children with acute TB, who also have impaired functional T-cell responses. Our data suggest that childhood TB is associated with an acquired immune defect, potentially resulting in failure to contain the pathogen. Elucidation of the mechanism causing the immune paresis may identify new treatment and prevention strategies

Mycobacteria counteract a TLR-mediated nitrosative defense mechanism in a zebrafish infection model.

Pulmonary tuberculosis (TB), caused by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb), is a major world health problem. The production of reactive nitrogen species (RNS) is a potent cytostatic and cytotoxic defense mechanism against intracellular pathogens. Nevertheless, the protective role of RNS during Mtb infection remains controversial. Here we use an anti-nitrotyrosine antibody as a readout to study nitration output by the zebrafish host during early mycobacterial pathogenesis. We found that recognition of Mycobacterium marinum, a close relative of Mtb, was sufficient to induce a nitrosative defense mechanism in a manner dependent on MyD88, the central adaptor protein in Toll like receptor (TLR) mediated pathogen recognition. However, this host response was attenuated by mycobacteria via a virulence mechanism independent of the well-characterized RD1 virulence locus. Our results indicate a mechanism of pathogenic mycobacteria to circumvent host defense in vivo. Shifting the balance of host-pathogen interactions in favor of the host by targeting this virulence mechanism may help to alleviate the problem of infection with Mtb strains that are resistant to multiple drug treatments

Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana: a model for the mercurial intoxication of the Wayana Amerindians

International audienc