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Tuberculosis (TB) remains a major threat to human health. Understanding the strategies mycobacteria take to overcome immune defense is important in order to control the infection. Micro (mi)RNAs are master regulators of most pathways in the human body.  Infection with mycobacterium impacts upon the host metabolic pathways as they are subverted to obtain the nutrition for intracellular TB survival. In this study, we aimed to investigate the effect of Bacillus Calmette-Guérin (BCG) infection on the expression of three miRNAs (miR-1224, -484 and -425), which are important in infection and in the regulation of metabolic pathways. Peripheral blood monocyte-derived macrophage (MDM) cultures were prepared and infected with BCG at a multiplicity of infection (MOI)=10 or left uninfected as a control. 72h post-infection, RNA was extracted from the cultured cells and cDNA synthesis and real-time PCR performed. Expression levels miRNAs were normalized to the levels of U6 snRNA (Rnu6) using the 2-ΔΔCt method. Infection with BCG resulted in a highly significant increase in miR-1224 expression (24.4±3.8-fold induction) in human MDMs. The induction of miR-484 (1.8±0.3-fold increase) and of miR-425 (1.2±0.2-fold increase) was less increased compared to miR-1224. Mycobacterium tolerates a hostile microenvironment by escaping from lysosomal degradation and providing a lipid-rich niche by trigger with and re-pattering host metabolism. This study highlighted the potential roles of miRNAs in host responses upon mycobacterium infection. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) and tobacco use are two major alarming global health issues posing immense threats to human populations. Mycobacterium tuberculosis (MTB) by activation of macrophages could induce the sequences of cells activation and releases of inflammatory cytokines such as CXCL-8, Il-12 and TNF-α which in turn induces the immune system network. However no information is available on other activity of cells by MTB and smoking. In the current study we aimed to investigate the serum levels TNF-a, CXCL-8 and phagocytosis capacity in tuberculosis patients with and without smoking. 103 subjects entered the study including 61 new diagnosed pulmonary TB patients (23 smokers and 38 nonsmokers) and 42 control healthy subjects. The phagocytosis of fluorescein isothiocyanate dextran (FITC-dextran) in blood monocytes/macrophages through flowcytometry was assessed. Serum levels of TNF-a and CXCL-8 were analyzed by ELISA methods. A lower percentage of cells from TB patients who smoked [50.29% (43.4-57.2), p<0.01] took up FITC-dextran after 2h compared to non-smoking TB subjects [71.62% (69.2-74.1)] and healthy cases [97.45% (95.9-99.1). Phagocytic capacity was inversely correlated with cigarette smoking as measured by pack years (r=-0.73, p<0.001). The serum levels of TNF-a and CXCL-8 were significantly higher in the TB patients who smoked compared to the TB non-smoker group (p<0.001, p<0.01 respectively). Blood monocytes/macrophages from TB patients have reduced phagocytic capacity which is further reduced in TB patients who smoke. Smoking enhanced serum levels of TNF-a and CXCL-8 suggesting a greater imbalance between the proinflammatory and anti-inflammatory factors in these patients. [ABSTRACT FROM AUTHOR]

The immunopathology of sarcoidosis remains elusive despite years of research into this multiorgan disease.However, recent studies have provided new insights into the genetics and immune components involved in the clinical manifestation of the disease. Granulomatous inflammation is due to the host immune response to a persistent poorly degradable unknown antigen.Mycobacterium tuberculosis (MTB) is the major disease driver in many patients. The immune mechanisms that cause this disease start with the antigenic stimulus, followed by T-cell, macrophage and dendritic cell activation via a classic MHC II-mediated pathway. In addition, the profile of immune mediators reported in sarcoidosis indicates that the inflammasome pathway plays a critical role in disease pathogenesis. Increased understanding of the signal transductions pathways involved in the induction of inflammatory processes in sarcoidosis could give rise to new therapeutic approaches in future. [ABSTRACT FROM AUTHOR]