Inhibition of the PERK/TXNIP/NLRP3 Axis by Baicalin Reduces NLRP3 Inflammasome-Mediated Pyroptosis in Macrophages Infected with Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) remains a significant threat to global health as it induces granuloma and systemic inflammatory responses during active tuberculosis. Mtb can induce macrophage pyroptosis, leading to the release of IL-1β and tissue damage, promoting its spread. Here, we established an in vitro Mtb-infected macrophage model to seek an effective antipyroptosis agent. Baicalin, isolated from Radix Scutellariae, was found to reduce pyroptosis in Mtb-infected macrophages. Baicalin could inhibit activation of the PERK/eIF2α pathway and thus downregulates TXNIP expression and subsequently reduces activation of the NLRP3 inflammasome, resulting in reduced pyroptosis in Mtb-infected macrophages. In conclusion, baicalin reduced pyroptosis by inhibiting the PERK/TXNIP/NLRP3 axis and might thus be a new adjuvant host-directed therapy (HDT) drug.

Leishmania Hijacks microRNA Import-Export Machinery of Infected Macrophage and Survives by Cross-Communicating Host miR-146a to Subjugate HuR and miR-122 in Neighbouring cells

Leishmania donovani, the causative agent of visceral leishmaniasis, infects and resides within tissue macrophage cells of the mammalian host. It is not clear how the parasite infected cells cross-talk with the non-infected cells in the infection niche to regulate the infection process. Interestingly, miRNAs, the regulatory small RNAs of the host, could get trafficked into and out of infected cells as part of extracellular vesicles to ensure exchange of the epigenetic signals and can regulate the expression of their target genes in both donor and recipient cells. Leishmania, for its survival in host macrophage, adopts a dual strategy to regulate the intercellular transport of host miRNAs. The parasite, by preventing mitochondrial function of the host cells, restricts the entry of liver cell derived miR-122 containing extracellular vesicles in infected macrophage to curtail the inflammatory response by miR-122. The parasite reciprocally upregulates the extracellular export of anti-inflammatory miR-146a from the infected cells. The exported miR-146a restricts miR-122 production in liver cells and polarizes neighbouring naïve macrophages to the M2 state. miR-146a upregulates IL-10 in neighbouring macrophages where miR-146a dominates the RNA binding and miRNA suppressor protein HuR to inhibit the expression of proinflammatory cytokine mRNAs having HuR-interacting AU-rich elements and polarized the recipient cells to M2 stage.Graphical AbstractKey FindingsLeishmania stops vesicular entry of inflammatory miR-122 in infected cells by causing mitochondrial depolarizationLeishmania secrets miR-146a from infected cells to stop miR-122 production in neighbouring hepatocytesmiR-146a containing vesicles secreted by infected cells stops inflammatory response in recipient naïve macrophagemiR-146 targets RNA binding protein HuR to stop inflammatory cytokine production

Exosomal miR-106b-5p promotes Mtb survival via targeting CREB5 followed by SOAT1-CIDEC and CASP9-CASP3 pathway

Tuberculosis(TB) is one of the top ten fatal diseases, but the research on the mechanism of TB is still not perfect. Exosome, as an important intercellular signal transmission signal vehicle and the mechanism of exosomes in the interaction between macrophages and Mycobacterium tuberculosis(Mtb), is crucial for TB treatment. In the study, we found that exosomes, derived from Mtb-infected macrophage, exhibited differential enrichment in different organs in mice, causing inflammatory cell infiltration in lungs. Further experiments in vitro showed that exosomes resulted in increased lipid synthesis and inhibition of apoptosis in normal macrophages. In order to further explore its molecular mechanism, bioinformatics analysis showed that miR-106b-5p was up-regulated in exosomes. Subsequently, we verified miR-106b-5p was increased through a large number of blood samples from TB patients. In addition, we demonstrated that miR-106b-5p was upregulated in exosomes from Mtb-infected macrophages, which can be engulfed by uninfected macrophages and further result in miR-106b-5p increase. We next found that miR-106b-5p mediated the same effect as the exosomes derived from infected macrophage. Through further research, we indicated that miR-106b-5p promoted lipid droplet accumulation through regulation of Creb5-SOAT1-CIDEC and suppressed macrophage apoptosis via Creb5-CASP9-CASP3 pathway, which ultimately led to Mtb survival. These findings provide a certain theoretical basis and ideas for the diagnosis and treatment of TB as well as the selection of biomarkers.

Macrophage supernatant infected with Leishmania major mediates the cytology of fibroblast cells in skin wounds

Objective: Healing of Cutaneous Leishmaniasis relies on the effective and modulates protective immune responses. Although the immune system is necessary to eliminate the parasite, it could be considered as the main cause of ulcers. Therefore, main aim of this study was to explore the possible regulatory functions of macrophage supernatant infected with Leishmania major on the fibroblast cells. Materials and Methods: In this experimental study, different concentrations of infected macrophage supernatant extract (50, 100, 150, 200, and 250μg/mL) were tested at different times (6, 24, 48, and 72h) and the effect of the leishmanicidal extract on fibroblast cells was determined by MTS assay. Also, the flow-cytometry technique was used for the investigation of apoptosis induction percentage. Results: MTS assay showed that the leishmanicidal effect of infected macrophage supernatant extract was dependent on the concentration and the time of treatment. So, the best efficacy was observed in 200 μg/mL with 72 hours exposure time. Flow cytometry analysis showed that the infected macrophage supernatant extract could induce apoptosis in cultured fibroblasts. Conclusions: We have demonstrated that reduction of survival rate and induction of apoptosis in fibroblasts displayed a similar manner to keratinocytes when exposed to infected macrophages with L. major. Our data suggest that such a phenomenon can be the underlying cause of lesions with scarring, and future, the mechanism remains to be elucidated.

The Role of Metallic Nanoparticles in Inhibition of Mycobacterium Tuberculosis and Enhances Phagosome Maturation into the Infected Macrophage

This review focuses on the role of gallium (Ga) nanoparticles (NPs) to enhance phagosome maturation into the Mycobacteriumtuberculosis-infected macrophage and the role of magnetic iron NPs as nanocarriers of antituberculosis drugs. The literature shows that silver (Ag) and zinc oxide (ZnO) NPs with dimensions less than 10 nm can penetrate directly through the macrophage bilayer membrane. Ag NPs increase the permeability membrane by motiving the aggregation of proteins in the periplasmic space and forming nano-sized pores. ZnO NPs can interact with the membrane of M. tuberculosis, which leads to the formation of surface pores and the release of intracellular nucleotides. The colloidal Ag:ZnO mixture NPs with 1:1 ratio can eliminate M. tuberculosis and shows the lowest cytotoxicity effects on MCF-7 and THP-1 cell lines. Ag/ZnO nanocrystals are not able to kill M. tuberculosis alone ex-vivo. Hence, bimetallic gold (Au)/Ag NPs possessed high efficiency to inhibit M. tuberculosis in an ex-vivo THP-1 infection model. Co-delivery of mixed MeNPs into a polymeric carrier collaborated to selective uptake by macrophages through passive targeting, initial burst release of ions from the encapsulated metallic (Me) NPs, and eventually, reduction of MeNPs toxicity, and plays a pivotal role in increasing the antitubercular activity compared to use alone. In addition, Ga NPs can import drugs to the macrophage, inhibit M. tuberculosis growth, and reduce the inhibition of phagosome maturation. Magnetic encapsulated NPs exhibited good drug release properties and might be suitable as carriers of antituberculosis drugs.