No abstract

Tuberculosis remains a serious threat worldwide. For this reason, it is necessary to identify agents that shorten the duration of treatment, strengthen the host immune system, and/or decrease the damage caused by the infection. Statins are drugs that reduce plasma cholesterol levels and have immunomodulatory, anti-inflammatory and antimicrobial effects. Although there is evidence that statins may contribute to the containment of Mycobacterium tuberculosis infection, their effects on peripheral blood mononuclear cells (PBMCs) involved in the immune response have not been previously described. Using PBMCs from 10 healthy subjects infected with M. tuberculosis H37Rv, we analyzed the effects of simvastatin on the treatment of the infections in an in vitro experimental model. Direct quantification of M. tuberculosis growth (in CFU/mL) was performed. Phenotypes and cell activation were assessed via multi-color flow cytometry. Culture supernatant cytokine levels were determined via cytokine bead arrays. The induction of apoptosis and autophagy was evaluated via flow cytometry and confocal microscopy. Simvastatin decreased the growth of M. tuberculosis in PBMCs, increased the proportion of NKT cells in culture, increased the expression of co-stimulatory molecules in monocytes, promoted the secretion of the cytokines IL-1β and IL-12p70, and activated apoptosis and autophagy in monocytes, resulting in a significant reduction in bacterial load. We also observed an increase in IL-10 production. We did not observe any direct antimycobacterial activity. This study provides new insight into the mechanism through which simvastatin reduces the mycobacterial load in infected PBMCs. These results demonstrate that simvastatin activates several immune mechanisms that favor the containment of M. tuberculosis infection, providing relevant evidence to consider statins as candidates for host-directed therapy. They also suggest that future studies are needed to define the roles of statin-induced anti-inflammatory mechanisms in tuberculosis treatment.

No abstract

Cervical cancer incidence remains highly frequent in developing countries. It is possible that populations of these countries are exposed to more oncogenic human papillomavirus (HPV) variants. Functional differences among high-risk HPV variants have been described, suggesting repercussions on their oncogenic potential. In this report, we demonstrate that the long control region (LCR) of HPV18 variants has distinct transcriptional activities in different cervical cancer cell lines. African (Af)-LCR possessed the lowest transcriptional activity; its sequence harbors the highest number of nucleotide changes among the HPV18 variants analyzed. Some of these embedded in identified transcription-factor-binding sites, suggesting a less aggressive biological activity possibly involved in a slower progression of cervical lesions. Asian-Amerindian LCR showed distinct activities among cell types, while European LCR activity was similar in cell lines tested. Despite multiple nucleotide substitutions found in HPV18 E2 variant genes, their repressive activities over homologous LCRs were not distinct among variants.

No abstract

Titanium dioxide nanoparticles (TiO2 NPs) are widely used for industrial and commercial applications. Once inside the body, they translocate into the bloodstream and reach different areas of the cardiovascular system including the heart, increasing the risk of developing cardiovascular diseases; consequently, the investigation of their interaction with cardiac cells is required. We previously showed that TiO2 NPs are internalized by H9c2 rat cardiomyoblasts, and here, we examined the molecular mechanisms underlying this process. TiO2 NPs internalization was evaluated by transmission electron microscopy, time-lapse microscopy, and flow cytometry. Changes in the actin cytoskeleton were studied by phalloidin staining. Endocytic uptake mechanisms for nanoparticles were probed with chemical inhibitors, whereas clathrin and dynamin expression was measured by Western blot. Cellular uptake of TiO2 NPs occurred early after 30 min exposure, and large aggregates were observed after 1 h. Actin cytoskeleton reorganization included cell elongation plus lower density and stability of actin fibers. Cytochalasin-D inhibited TiO2 NPs uptake, indicating actin-mediated internalization. Dynamin and clathrin levels increased early after TiO2 NPs exposure, and their inhibition reduced nanoparticle uptake. Therefore, TiO2 NPs internalization by H9c2 rat cardiomyoblasts involves actin cytoskeleton reorganization and clathrin/dynamin-mediated endocytosis.

No abstract

The Wnt/β-catenin signaling pathway regulates cell proliferation and differentiation and its aberrant activation in cervical cancer has been described. Persistent infection with high risk human papillomavirus (HR-HPV) is the most important factor for the development of this neoplasia, since E6 and E7 viral oncoproteins alter cellular processes, promoting cervical cancer development. A role of HPV-16 E6 in Wnt/β-catenin signaling has been proposed, although the participation of HPV-18 E6 has not been previously studied. The aim of this work was to investigate the participation of HPV-18 E6 and E6*I, in the regulation of the Wnt/β-catenin signaling pathway. Here, we show that E6 proteins up-regulate TCF-4 transcriptional activity and promote overexpression of Wnt target genes. In addition, it was demonstrated that E6 and E6*I bind to the TCF-4 (T cell factor 4) and β-catenin, impacting TCF-4 stabilization. We found that both E6 and E6*I proteins interact with the promoter of Sp5, in vitro and in vivo. Moreover, although differences in TCF-4 transcriptional activation were found among E6 intratype variants, no changes were observed in the levels of regulated genes. Furthermore, our data support that E6 proteins cooperate with β-catenin to promote cell proliferation.