Spiropyrimidinetriones: a Class of DNA Gyrase Inhibitors with Activity against Mycobacterium tuberculosis and without Cross-Resistance to Fluoroquinolones.

Described here is a series of spiropyrimidinetrione (SPT) compounds with activity against Mycobacterium tuberculosis through inhibition of DNA gyrase. The SPT class operates via a novel mode of inhibition, which involves Mg2+-independent stabilization of the DNA cleavage complex with DNA gyrase and is thereby not cross-resistant with other DNA gyrase-inhibiting antibacterials, including fluoroquinolones. Compound 22 from the series was profiled broadly and showed in vitro cidality as well as intracellular activity against M. tuberculosis in macrophages. Evidence for the DNA gyrase mode of action was supported by inhibition of the target in a DNA supercoiling assay and elicitation of an SOS response seen in a recA reporter strain of M. tuberculosis. Pharmacokinetic properties of 22 supported evaluation of efficacy in an acute model of M. tuberculosis infection, where modest reduction in CFU numbers was seen. This work offers promise for deriving a novel drug class of tuberculosis agent without preexisting clinical resistance.

A molecular physiological review of vegetative desiccation tolerance in the resurrection plant Xerophyta viscosa (Baker).

MAIN CONCLUSION: Provides a first comprehensive review of integrated physiological and molecular aspects of desiccation tolerance Xerophyta viscosa. A synopsis of biotechnological studies being undertaken to improve drought tolerance in maize is given. Xerophyta viscosa (Baker) is a monocotyledonous resurrection plant from the family Vellociacea that occurs in summer-rainfall areas of South Africa, Lesotho and Swaziland. It inhabits rocky terrain in exposed grasslands and frequently experiences periods of water deficit. Being a resurrection plant it tolerates the loss of 95% of total cellular water, regaining full metabolic competency within 3 days of rehydration. In this paper, we review some of the molecular and physiological adaptations that occur during various stages of dehydration of X. viscosa, these being functionally grouped into early and late responses, which might be relevant to the attainment of desiccation tolerance. During early drying (to 55% RWC) photosynthesis is shut down, there is increased presence and activity of housekeeping antioxidants and a redirection of metabolism to the increased formation of sucrose and raffinose family oligosaccharides. Other metabolic shifts suggest water replacement in vacuoles proposed to facilitate mechanical stabilization. Some regulatory processes observed include increased presence of a linker histone H1 variant, a Type 2C protein phosphatase, a calmodulin- and an ERD15-like protein. During the late stages of drying (to 10% RWC) there was increased expression of several proteins involved in signal transduction, and retroelements speculated to be instrumental in gene silencing. There was induction of antioxidants not typically found in desiccation-sensitive systems, classical stress-associated proteins (HSP and LEAs), proteins involved in structural stabilization and those associated with changes in various metabolite pools during drying. Metabolites accumulated in this stage are proposed, inter alia, to facilitate subcellular stabilization by vitrification process which can include glass- and ionic liquid formation.

Quantifying spatial dynamics of Mycobacterium tuberculosis infection of human macrophages using microfabricated patterns.

Macrophages provide a first line of defense against invading pathogens, including the leading cause of bacterial mortality, Mycobacterium tuberculosis (Mtb). A challenge for quantitative characterization of host-pathogen processes in differentially polarized primary human monocyte-derived macrophages (MDMs) is their heterogeneous morphology. Here, we describe the use of microfabricated patterns that constrain the size and shape of cells, mimicking the physiological spatial confinement cells experience in tissues, to quantitatively characterize interactions during and after phagocytosis at the single-cell level at high resolution. Comparing pro-inflammatory (M1) and anti-inflammatory (M2) MDMs, we find interferon-γ stimulation increases the phagocytic contraction, while contraction and bacterial uptake decrease following silencing of phagocytosis regulator NHLRC2 or bacterial surface lipid removal. We identify host organelle position alterations within infected MDMs and differences in Mtb subcellular localization in line with M1 and M2 cellular polarity. Our approach can be adapted to study other host-pathogen interactions and coupled with downstream automated analytical approaches.

Immunopathogenic overlap between COVID-19 and tuberculosis identified from transcriptomic meta-analysis and human macrophage infection.

Current and previous tuberculosis (TB) increase the risk of COVID-19 mortality and severe disease. To identify mechanisms of immunopathogenic interaction between COVID-19 and TB, we performed a systematic review and patient-level meta-analysis of COVID-19 transcriptomic signatures, spanning disease severity, from whole blood, PBMCs, and BALF. 35 eligible signatures were profiled on 1181 RNA-seq samples from 853 individuals across the spectrum of TB infection. Thirteen COVID-19 gene-signatures had significantly higher "COVID-19 risk scores" in active TB and latent TB progressors compared with non-progressors and uninfected controls (p<0·005), in three independent cohorts. Integrative single-cell-RNAseq analysis identified FCN1- and SPP1-expressing macrophages enriched in severe COVID-19 BALF and active TB blood. Gene ontology and protein-protein interaction networks identified 12-gene disease-exacerbation hot spots between COVID-19 and TB. Finally, we in vitro validated that SARS-CoV-2 infection is increased in human macrophages cultured in the inflammatory milieu of Mtb-infected macrophages, correlating with TMPRSS2, IFNA1, IFNB1, IFNG, TNF, and IL1B induction.

Recent progress in understanding immune activation in the pathogenesis in HIV-tuberculosis co-infection.

PURPOSE OF REVIEW: Tuberculosis is the leading infectious cause of death worldwide, and HIV-1 the best recognized risk factor for active TB. This review focuses on immune complex formation; the interplay of type I and II interferon signaling; and T-cell activation in HIV-TB pathogenesis. RECENT FINDINGS: Circulating immune complexes and complement, and Fcγ signaling in whole blood act as early markers of TB disease in HIV-1-infected persons. HIV-1 is associated with a type I interferon response in whole blood, reducing the specificity of TB biomarkers dependent on type I and II interferon genes. Type I and type II interferons are implicated in both protection and TB disease, a protective outcome may depend on modulating these pathways. Whilst M. tuberculosis-specific CD4 T cells are preferentially depleted during HIV-1 infection, activation markers on M. tuberculosis-specific CD4 T cells, in particular HLA-DR, reflect immune activation and have promise as biomarkers of M. tuberculosis disease activity in individuals with HIV-1. SUMMARY: TB pathogenesis in HIV-1 involves a complex interaction of underlying activation of both the innate and adaptive immune systems. Further research is required to understand whether biomarkers of activation could be used to predict or quantify TB disease in the context of HIV-1 infection.