Studies of the role of macrophages in phagocytosis are of great theoretical and practical importance for understanding how these cells are involved in the organism’s defense response and in the...

Rifampicin is a widely used drug for antituberculosis therapy. Its target is the bacterial RNA polymerase. After entry into the human or mammalian organism, rifampicin is accumulated in cells of epithelial origin (kidneys, liver, lungs) where it induces apoptosis, necrosis, and fibrosis. The purpose of this study was to determine the intracellular mechanisms leading to rifampicin-induced pathological changes and cell death. We analyzed the survival and state of the chondriome of cultured epithelial cells of the SPEV line under the influence of rifampicin. Our data show that the drug induces pronounced pathological changes in the network and ultrastructure of mitochondria, and their dysfunction results in excessive production of reactive oxygen species and release of cytochrome c. These data suggest the initiation of the mitochondrial pathway of apoptosis. Simultaneously, we observed inhibition of cell proliferation and changes in morphology of the epithelial cells toward fibroblast-like appearance, which could indicate induction of epithelial-mesenchymal transition. Thus, mitochondria are the main potential target for rifampicin in cells of epithelial origin. We suggest that similar mechanisms of pathological changes can be induced in vivo in organs and tissues accumulating rifampicin during chemotherapy of bacterial infectious diseases.

P-glycoprotein (encoded by the ABCB1 gene) has a dual role in regulating inflammation and reducing chemotherapy efficacy in various diseases, but there are few studies focused on pulmonary TB patients. In this study, our objective was to identify a list of genes that correlate with high and low levels of ABCB1 gene expression in the lungs of pulmonary TB patients with different activity of chronic granulomatous inflammation. We compared gene expression in two groups of samples (with moderate and high activity of tuberculomas) to identify their characteristic gene signatures. Gene expression levels were determined using quantitative PCR in samples of perifocal area of granulomas, which were obtained from 65 patients after surgical intervention. Subsequently, two distinct gene signatures associated with high inflammation activity were identified. The first signature demonstrated increased expression of HIF1a, TGM2, IL6, SOCS3, and STAT3, which correlated with high ABCB1 expression. The second signature was characterized by high expression of TNFa and CD163 and low expression of ABCB1. These results provide insight into various inflammatory mechanisms and association with P-gp gene expression in lung tissue of pulmonary TB patients and will be useful in the development of a host-directed therapy approach to improving the effectiveness of anti-TB treatment.

One of the key requirements for the diagnosis of pulmonary tuberculosis is the identification of M. tuberculosis in tissue. In this paper, we present the advantages of specific fluorescent antibody labelling, combined with laser scanning confocal microscopy (LSCM), for the detection of M. tuberculosis in histological specimens of lung tissues. We demonstrate that the application of LSCM allows: (i) The automatic acquisition of images of the whole slice and, hence, the determination of regions for subsequent analysis; (ii) the acquisition of images of thick (20–40 μm) slices at high resolution; (iii) single bacteria identification; and (iv) 3D reconstruction, in order to obtain additional information about the distribution, size, and morphology of solitary M. tuberculosis; as well as their aggregates and colonies, in various regions of tuberculosis inflammation. LSCM allows for the discrimination of the non-specific fluorescence of bacteria-like particles and their aggregates presented in histological lung samples, from the specific fluorescence of labelled M. tuberculosis, using spectrum emission analysis. The applied method was effective in the identification of M. tuberculosis in lung histological samples with weak Ziehl–Neelsen staining. Altogether, combining immunofluorescent labelling with the application of LSCM visualization significantly increases the effectiveness of M. tuberculosis detection.

Tuberculosis is rapidly becoming a major health problem. The rise in tuberculosis incidence stimulates efforts to develop more effective delivery systems for the existing antituberculous drugs while decreasing the side effects. The nanotechnology may provide novel drug delivery tools allowing controlled drug release. Rifampicin is one of the main antituberculous drugs, characterized by high toxicity, and Poly (L-lactic acid) (PLLA) is a biodegradable polymer used for the preparation of encapsulated drugs. The aim of our work was to evaluate the toxicity of rifampicin-PLLA nanoparticles against Mycobacterium bovis BCG using human macrophage THP-1 cell line. Our data demonstrate that rifampicin-PLLA is effective against M. bovis BCG in the infected macrophages. The drug is inducing the dysfunction of mitochondria and apoptosis in the macrophages and is acting as a potential substrate of Pgp thereby modulating cell chemosensitivity. The severity of the toxic effects of the rifampicin-PLLA nanoparticles is increasing in a dose-dependent manner. We suggest that free rifampicin induces death of M. bovis BCG after PLLA degradation and diffusion from phago-lysosomes to cytoplasm causing mitochondria dysfunction and affecting the Pgp activity.

Background. The effect on the activity of the multidrug resistance protein P-glycoprotein (P-gp, MDR1 gene) in pro-inflammatory (M1) human macrophages is considered one of the promising strategies for increasing the effectiveness of the treatment in patients with pulmonary tuberculosis: P-gp activity is considered a factor that reduces intracellular accumulation of rifampicin (RIF), a substrate for P-gp. The aim of this work was to reveal the effect of the therapeutic concentration of RIF on the activity of P-gp in M1 human macrophages. The objectives were as follows: to determine the expression levels of the MDR1 gene, P-gp protein, as well as its functional activity at different periods of cell differentiation and under the influence of RIF.Material and methods. The following cell lines were used in the work: suspension cells of promonocytic leukemia THP-1 and THP-1 macrophages induced by phorbol ether according to the pro-inflammatory phenotype. Suspension cells of myeloid leukemia K562/IS-9 transfected with the MDR1 gene were used as a comparison group. An important factor is the choice of the experimental concentration of RIF: the average concentration of the drug in patients with pulmonary tuberculosis was 10 µg/ml. The methods of RT-PCR, immunocytochemistry, and flow cytometry were used in the work.Results and discussion. The induction of MDR1 gene expression in M1 macrophages under short-term exposure to a therapeutic concentration of RIF was revealed. This effect is typical only for THP-1 macrophages, in which a significant functional activity of P-gp is registered. This induction does not occur in the cells with no detectable P-gp activity (THP-1 suspension cells). This indicates the presence of different mechanisms of RIF influence on MDR1, which can be used to develop a strategy for P-gp inhibition in inflammatory macrophages.Conclusion. Given the key role of macrophages in tuberculosis, further evaluation of MDR1/P-gp in the surgical material of patients with pulmonary tuberculosis is necessary, which makes it possible to draw a conclusion that it is necessary to develop and apply drug strategies aimed at blocking the functional activity of P-gp and choosing more effective anti-tuberculosis therapy regimens.