Rapid susceptibility testing for slowly growing nontuberculous mycobacteria using a colorimetric microbial viability assay based on the reduction of water-soluble tetrazolium WST-1

2,3,5-triphenyl tetrazolium chloride as colorimetric indicator for drug susceptibility testing against nontuberculous mycobacteria

This study aimed to propose and evaluate a drug susceptibility testing (DST) using the 2,3,5-triphenyl tetrazolium chloride (TTC) as a colorimetric indicator against Mycobacterium abscessus complex (MABC), M. avium complex (MAC), and M. kansasii strains, main nontuberculous mycobacteria (NTM) of clinical relevance. Our results demonstrated that the assay using TTC and the broth microdilution method recommended by the Clinical and Laboratory Standards Institute had essential agreement above 91%, 92%, and 100%, for drugs tested against MABC, MAC, and M. kansasii strains, respectively. Categorical agreement above 91% was obtained for most drugs tested against MABC, except to cefoxitin (76.5%). For drugs tested against MAC and M. kansasii, categorical agreement above 92% and 100% was observed, respectively. TTC showed to be a promising colorimetric indicator of growth to be used in DST for NTM, allowing an easier reading of results.

Trichinella spiralis cathepsin L induces macrophage M1 polarization via the NF-κB pathway and enhances the ADCC killing of newborn larvae

BACKGROUND

During the early stages of Trichinella spiralis infection, macrophages predominantly undergo polarization to the M1-like phenotype, causing the host's inflammatory response and resistance against T. spiralis infection. As the disease progresses, the number of M2-type macrophages gradually increases, contributing to tissue repair processes within the host. While cysteine protease overexpression is typically associated with inflammation, the specific role of T. spiralis cathepsin L (TsCatL) in mediating macrophage polarization remains unknown. The aim of this study was to assess the killing effect of macrophage polarization mediated by recombinant T. spiralis cathepsin L domains (rTsCatL2) on newborn larvae (NBL).

METHODS

rTsCatL2 was expressed in Escherichia coli strain BL21. Polarization of the rTsCatL2-induced RAW264.7 cells was analyzed by enzyme-linked immunosorbent assay (ELISA), quantitative PCR (qPCR), western blot, immunofluorescence and flow cytometry. The effect of JSH-23, an inhibitor of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), on rTsCatL2-induced M1 polarization investigated. Cytotoxic effects of polarized macrophages on NBL were observed using in vitro killing assays.

RESULTS

Following the co-incubation of rTsCatL2 with RAW264.7 murine macrophage cells, qPCR and ELISA revealed increased transcription and secretion levels of inducible nitric oxide synthase (iNOS), interleukin (IL)-6, IL-1β and tumor necrosis factor alpha (TNF-α) in macrophages. Western blot analysis showed a significant increase in iNOS protein expression, while the expression level of arginase-1 protein remained unchanged. Flow cytometry revealed a substantial increase in the number of CD86-labeled macrophages. The western blot results also indicated that rTsCatL2 increased the expression levels of phospho-NF-κB and phospho-nuclear factor-κB inhibitor alpha (IκB-α) proteins in a dose-dependent manner, while immunofluorescence revealed that rTsCatL2 induced nuclear translocation of the p65 subunit of NF-κB (NF-κB p65) protein in macrophages. The inhibitory effect of JSH-23 suppressed and abrogated the effect of rTsCatL2 in promoting M1 macrophage polarization. rTsCatL2 mediated polarization of macrophages to the M1-like phenotype and enhanced macrophage adhesion and antibody-dependent cell-mediated cytotoxicity (ADCC) killing of NBL.

CONCLUSIONS

The results indicated that rTsCatL2 induces macrophage M1 polarization via the NF-κB pathway and enhances the ADCC killing of NBL. This study provides a further understanding of the interaction mechanism between T. spiralis and the host.

Investigating the Activity of Indole-2-on Derivative Src Kinase Inhibitors Against Chronic Myeloid Leukemia Cells

BACKGROUND

Src family tyrosine kinases play a potential role in Bcr-Abl-induced leukemogenesis. Src kinase inhibitors are reported as selective inhibitors of chronic myeloid leukemia.

OBJECTIVE

Since Src kinase inhibitors have an inhibitive effect on chronic myeloid leukemia, indole derivatives (C-1, C-2, C-3) previously found as potent inhibitors of Src kinase were tested against chronic myeloid leukemia in this study.

METHODS

Cell viability of K562 and R/K562 cells, antiproliferative and antioxidant effects, and inhibition profiles of Bcr-Abl kinase of indole derivatives were determined compared to dasatinib and imatinib.

RESULTS

The results showed that compounds affected cell proliferation and decreased the levels of Bcr/Abl. These results confirmed that the antileukemic activity of compounds was related to Bcr/Abl expression. Docking studies also presented that compounds are inhibitors of both Src and Abl kinases. Calculation of drug-like properties showed that compounds could be potential drug candidates.

CONCLUSION

Among indole-2-on derivatives, previously identified as Src kinase inhibitors, C-2 has been discovered to be a strong anticancer drug that is active against susceptible and resistant K562 cell lines and induces apoptosis.

Estrogen-induced epigenetic silencing of FTH1 and TFRC genes reduces liver cancer cell growth and survival

Estrogen (E2) regulates hundreds of genes involved in cell metabolism and disrupts iron homoeostasis in various cell types. Herein, we addressed whether E2-induced epigenetic modifications are involved in modulating the expression of iron-regulatory genes. Epigenetic status of FTH1 and TFRC genes was assessed in E2-treated cancer cells. E2-induced DNA methylation was associated with decreased FTH1 and TFRC expression in Hep-G2 and Huh7 cells, but not in AGS or MCF7 cells. Demethylation with 5-Aza-2-deoxycytidine upregulated the expression of both these genes in Hep-G2 cells. The expression of DNMT3B, PRMT5, and H4R3me2s increased in E2-treated cells. Chromatin immunoprecipitation showed that E2 treatment recruited PRMT5 and H4R3me2s on FTH1 but not on TFRC. Knockdown of PRMT5, DNMT3B, and Estrogen-receptor alpha rescued FTH1 from E2-induced silencing. However, knockdown of DNMT3B alone blocked the inhibitory effects of E2 on TFRC. Analysis of human liver tissues in publicly available datasets showed that FTH1 and TFRC are highly expressed in primary liver tumours, but a lower expression is associated with better survival. Interestingly, we showed that the silencing of FTH1 and/or TFRC inhibited carcinogenesis in Hep-G2 cells. For the first time, our findings uncovered the novel signalling pathway involved in the protective effects of E2 against liver cancer.

Preclinical Models of Nontuberculous Mycobacteria Infection for Early Drug Discovery and Vaccine Research

Nontuberculous mycobacteria (NTM) represent an increasingly prevalent etiology of soft tissue infections in animals and humans. NTM are widely distributed in the environment and while, for the most part, they behave as saprophytic organisms, in certain situations, they can be pathogenic, so much so that the incidence of NTM infections has surpassed that of Mycobacterium tuberculosis in developed countries. As a result, a growing body of the literature has focused attention on the critical role that drug susceptibility tests and infection models play in the design of appropriate therapeutic strategies against NTM diseases. This paper is an overview of the in vitro and in vivo models of NTM infection employed in the preclinical phase for early drug discovery and vaccine development. It summarizes alternative methods, not fully explored, for the characterization of anti-mycobacterial compounds.

Extracellular vesicles enhance oxidative stress through P38/NF-kB pathway in ketamine-induced ulcerative cystitis

Long‐term abuse of ketamine causes ketamine‐induced cystitis. The functional alterations of bladder epithelial cells in microenvironment during cystitis remain poorly understood. Here, we explored extracellular vesicles (EV) alteration in ketamine‐induced toxicity. To simulate the high‐concentration ketamine environment in vivo, we established an in vitro model of high ketamine using human uroepithelial cells (SV‐HUC‐1). Cell viability and proliferation were assessed to evaluate the effects of various concentrations (0, 0.25, 0.5, 1, 2, 4 and 8 mmol/L) of ketamine on SV‐HUC‐1 cells. The cell supernatant cultured at a concentration (0, 1, 2, 4 mmol/L) of ketamine was selected for EV extraction and identified. Subsequently, we assessed different groups (ketamine, ketamine plus EV blocker, EV, EV plus extracellular vesicles blocker) of oxidative stress and expression of inflammation. Last, luciferase reporter assay was performed to study the transcriptional regulation of EV on the NF‐kB and P38 pathway. The results of our study suggested that treatment with 0, 1, 2 or 4 mmol/L ketamine altered the morphology and secretion capacity of extracellular vesicles. As the concentration of ketamine increased, the average particle size of EV decreased, but the crest size, particle concentration and EV protein increased. Moreover, after the addition of EV blocker, EV secreted at different concentrations were blocked outside the cell membrane, and the degree of oxidative stress decreased. Our study provided evidence that ketamine alters the secretion of EV by directly stimulating cells in inflammation microenvironment and EV play significant roles in intercellular signal communication and the formation of KIC.EV

Drug Susceptibility of 33 Reference Strains of Slowly Growing Mycobacteria to 19 Antimicrobial Agents

Objectives. Slowly growing mycobacteria (SGM) are prevalent worldwide and cause an extensive spectrum of diseases. Methods. In this study, the antimicrobial susceptibility of 33 reference strains of SGM to 19 antimicrobial agents was tested using a modified microdilution method. Results. Cefmetazole (32/33) and azithromycin (32/33) exhibited the highest antimicrobial activity, and dapsone (9/33) exhibited the lowest activity against the tested strains. Cefoxitin (30/33), cefoperazone (28/33), and cefepime (28/33) were effective against a high proportion of strains, and macrolides were also highly effective as well as offering the benefit of convenient oral administration to patients. Linezolid (27/33), meropenem (26/33), sulfamethoxazole (26/33), and tigecycline (25/33) showed the highest activity; clofazimine (20/33) and doxycycline (18/33) showed intermediate activity; and rifapentine (13/33), rifabutin (13/33), and minocycline (11/33) showed low antimicrobial activity, closely followed by thioacetazone (10/33) and pasiniazid (10/33), against the tested organisms. According to their susceptibility profiles, the slowly growing species Mycobacterium avium and Mycobacterium simiae were the least susceptible to the tested drugs, whereas Mycobacterium intracellulare, Mycobacterium asiaticum, Mycobacterium scrofulaceum, Mycobacterium szulgai, Mycobacterium branderi, and Mycobacterium holsaticum were the most susceptible. Conclusions. In summary, cephalosporins and macrolides, particularly cefmetazole, azithromycin, clarithromycin, and roxithromycin, showed good antimicrobial activity against the reference strains of SGM.