Background-Vitamin D was used to treat tuberculosis in the pre-antibiotic era, and its metabolites induce antimycobacterial immunity in vitro. Clinical trials investigating the effect of adjunctive vitamin D on sputum culture conversion are lacking.
Calcidiol, the major circulating metabolite of vitamin D, supports induction of pleiotropic antimicrobial responses in vitro. Vitamin D supplementation elevates circulating calcidiol concentrations, and thus has a potential role in the prevention and treatment of infection. The immunomodulatory effects of administering vitamin D to humans with an infectious disease have not previously been reported. To characterize these effects, we conducted a detailed longitudinal study of circulating and antigen-stimulated immune responses in ninety-five patients receiving antimicrobial therapy for pulmonary tuberculosis who were randomized to receive adjunctive high-dose vitamin D or placebo in a clinical trial, and who fulfilled criteria for per-protocol analysis. Vitamin D supplementation accelerated sputum smear conversion and enhanced treatment-induced resolution of lymphopaenia, monocytosis, hypercytokinaemia, and hyperchemokinaemia. Administration of vitamin D also suppressed antigen-stimulated proinflammatory cytokine responses, but attenuated the suppressive effect of antimicrobial therapy on antigenstimulated secretion of IL-4, CC chemokine ligand 5, and IFN-α. We demonstrate a previously unappreciated role for vitamin D supplementation in accelerating resolution of inflammatory responses during tuberculosis treatment. Our findings suggest a potential role for adjunctive vitamin D supplementation in the treatment of pulmonary infections to accelerate resolution of inflammatory responses associated with increased risk of mortality.adjunctive therapy | immunomodulation | antimicrobial peptides | matrix metalloproteinases | steroid hormones
Tuberculosis is classically divided into states of latent infection and active disease. Using combined positron emission and computed tomography in 35 asymptomatic, antiretroviral therapy naïve, HIV-1 infected adults with latent tuberculosis, we identified ten individuals with pulmonary abnormalities suggestive of subclinical, active disease who were significantly more likely to progress to clinical disease. Our findings challenge the conventional two-state paradigm and may aid future identification of biomarkers predictive of progression.
Summary
Matrix metalloproteinases (MMP) can degrade all components of pulmonary extracellular matrix. Mycobacterium tuberculosis induces production of a number of these enzymes by human macrophages, and these are implicated in the pathogenesis of pulmonary cavitation in tuberculosis. The active metabolite of vitamin D, 1α,25‐dihydroxyvitamin D3 [1α,25(OH)2D3], has previously been reported to inhibit secretion of MMP‐9 in human monocytes (MN), but its influence on the secretion and gene expression of MMP and tissue inhibitors of MMP (TIMP) in M. tuberculosis‐infected cells has not previously been investigated. We therefore determined the effects of 1α,25(OH)2D3 on expression, secretion and activity of a number of MMP and TIMP in M. tuberculosis‐infected human leucocytes; we also investigated the effect of 1α,25(OH)2D3 on the secretion of interleukin‐10 (IL‐10) and prostaglandin E2 (PGE2), both transcriptional regulators of MMP expression. We found that M. tuberculosis induced expression of MMP‐1, MMP‐7 and MMP‐10 in MN and MMP‐1 and MMP‐10 in peripheral blood mononuclear cells (PBMC). 1α,25(OH)2D3 significantly attenuated M. tuberculosis‐induced increases in expression of MMP‐7 and MMP‐10, and suppressed secretion of MMP‐7 by M. tuberculosis‐infected PBMC. MMP‐9 gene expression, secretion and activity were significantly inhibited by 1α,25(OH)2D3 irrespective of infection. In contrast, the effects of 1α,25(OH)2D3 on the expression of TIMP‐1, TIMP‐2 and TIMP‐3 and secretion of TIMP‐1 and TIMP‐2 were small and variable. 1α,25(OH)2D3 also induced secretion of IL‐10 and PGE2 from M. tuberculosis‐infected PBMC. These findings represent a novel immunomodulatory role for 1α,25(OH)2D3 in M. tuberculosis infection.
Immunology is a central theme when it comes to tuberculosis (TB). The outcome of human infection with Mycobacterium tuberculosis is dependent on the ability of the immune response to clear or contain the infection.In cases where this fails, the bacterium replicates, disseminates within the host, and elicits a pathologic inflammatory response, and disease ensues. Clinical presentation of TB disease is remarkably heterogenous, and the disease phenotype is largely dependent on host immune status. Onward transmission of M. tuberculosis to new susceptible hosts is thought to depend on an excessive inflammatory response causing a breakdown of the lung matrix and formation of lung cavities, but this varies in cases of underlying immunological dysfunction: for example, HIV is associated with less cavitation, while diabetes mellitus is associated with increased cavitation and risk of transmission. In compliance with the central theme of immunology in tuberculosis, we rely on detection of an adaptive immune response, in the form of interferon-gamma release assays or tuberculin skin tests, to diagnose infection with M. tuberculosis. Here we review the immunology of tuberculosis in the human host, focusing on cellular and humoral adaptive immunity as well as key features of innate immune responses and the underlying immunological dysfunction which associates with human TB risk factors. Our review is restricted to human immunology, and we highlight distinctions from the immunological dogma originating from animal models of tuberculosis, which pervade the field.
Tuberculous meningitis immune reconstitution inflammatory syndrome (TBM-IRIS) is characterized by severe, compartmentalized cerebral inflammation, involving mediators of innate and adaptive immune responses. A high baseline cerebrospinal fluid bacillary load predisposes to recurrent inflammation during antiretroviral therapy, manifesting as TBM-IRIS.
Background: Craniosynostosis, the premature fusion of calvarial sutures, is a common craniofacial abnormality. Causative mutations in more than 10 genes have been identified, involving fibroblast growth factor, transforming growth factor beta, and Eph/ephrin signalling pathways. Mutations affect each human calvarial suture (coronal, sagittal, metopic, and lambdoid) differently, suggesting different gene expression patterns exist in each human suture. To better understand the molecular control of human suture morphogenesis we used microarray analysis to identify genes differentially expressed during suture fusion in children with craniosynostosis. Expression differences were also analysed between each unfused suture type, between sutures from syndromic and non-syndromic craniosynostosis patients, and between unfused sutures from individuals with and without craniosynostosis.
32Understanding the events in early tuberculosis disease will facilitate the development of novel 33 tests to predict disease progression and interventions to prevent it. Blood
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