Dipterinyl calcium pentahydrate inhibits intracellular mycobacterial growth in human monocytes via the C-C chemokine MIP-1β and nitric oxide

Integrative Analysis of Human Macrophage Inflammatory Response Related to Mycobacterium tuberculosis Virulence

Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis, kills 1.5 to 1.7 million people every year. Macrophages are Mtb's main host cells and their inflammatory response is an essential component of the host defense against Mtb. However, Mtb is able to circumvent the macrophages' defenses by triggering an inappropriate inflammatory response. The ability of Mtb to hinder phagolysosome maturation and acidification, and to escape the phagosome into the cytosol, is closely linked to its virulence. The modulation of the host inflammatory response relies on Mtb virulence factors, but remains poorly studied. Understanding macrophage interactions with Mtb is crucial to develop strategies to control tuberculosis. The present study aims to determine the inflammatory response transcriptome and miRNome of human macrophages infected with the virulent H37Rv Mtb strain, to identify macrophage genetic networks specifically modulated by Mtb virulence. Using human macrophages infected with two different live strains of mycobacteria (live or heat-inactivated Mtb H37Rv and M. marinum), we quantified and analyzed 184 inflammatory mRNAs and 765 micro(mi)RNAs. Transcripts and miRNAs differently modulated by H37Rv in comparison with the two other conditions were analyzed using in silico approaches. We identified 30 host inflammatory response genes and 37 miRNAs specific for H37Rv virulence, and highlight evidence suggesting that Mtb intracellular-linked virulence depends on the inhibition of IL-1β-dependent pro-inflammatory response, the repression of apoptosis and the delay of the recruitment and activation of adaptive immune cells. Our findings provide new potential targets for the development of macrophage-based therapeutic strategies against TB.

Small molecule inhibitors and stimulators of inducible nitric oxide synthase in cancer cells from natural origin (phytochemicals, marine compounds, antibiotics)

Nitric oxide synthases (NOS) are a family of isoforms, which generate nitric oxide (NO). NO is one of the smallest molecules in nature and acts mainly as a potent vasodilator. It participates in various biological processes ranging from physiological to pathological conditions. Inducible NOS (iNOS, NOS2) is a calcium-independent and inducible isoform. Despite high iNOS expression in many tumors, the role of iNOS is still unclear and complex with both enhancing and prohibiting actions in tumorigenesis. Nature presents a broad variety of natural stimulators and inhibitors, which may either promote or inhibit iNOS response. In the present review, we give an overview of iNOS-modulating agents with a special focus on both natural and synthetic molecules and their effects in related biological processes. The role of iNOS in physiological and pathological conditions is also discussed.

STAT3 Represses Nitric Oxide Synthesis in Human Macrophages upon Mycobacterium tuberculosis Infection

Mycobacterium tuberculosis is a successful intracellular pathogen. Numerous host innate immune responses signaling pathways are induced upon mycobacterium invasion, however their impact on M. tuberculosis replication is not fully understood. Here we reinvestigate the role of STAT3 specifically inside human macrophages shortly after M. tuberculosis uptake. We first show that STAT3 activation is mediated by IL-10 and occurs in M. tuberculosis infected cells as well as in bystander non-colonized cells. STAT3 activation results in the inhibition of IL-6, TNF-α, IFN-γ and MIP-1β. We further demonstrate that STAT3 represses iNOS expression and NO synthesis. Accordingly, the inhibition of STAT3 is detrimental for M. tuberculosis intracellular replication. Our study thus points out STAT3 as a key host factor for M. tuberculosis intracellular establishment in the early stages of macrophage infection.

The Transcriptional Foundations of Sp110-mediated Macrophage (RAW264.7) Resistance to Mycobacterium tuberculosis H37Ra

Human tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a leading global health problem, causing 1.3 million deaths each year. The nuclear body protein, Sp110, has been linked to TB resistance and previous work showed that it enhances macrophage apoptosis upon Mtb infection. Here, we report on the role of Sp110 in transcriptional regulation of macrophage responses to Mtb through integrated transcriptome and mechanistic studies. Transcriptome analysis revealed that Sp110 regulates genes involved in immune responses, apoptosis, defence responses, and inflammatory responses. Detailed investigation revealed that, in addition to apoptosis-related genes, Sp110 regulates cytokines, chemokines and genes that regulate intracellular survival of Mtb. Moreover, Sp110 regulates miRNA expression in macrophages, with immune and apoptosis-related miRNAs such as miR-125a, miR-146a, miR-155, miR-21a and miR-99b under Sp110 regulation. Additionally, our results showed that Sp110 upregulates BCL2 modifying factor (Bmf) by inhibiting miR-125a, and forced expression of Bmf induces macrophage apoptosis. These findings not only reveal the transcriptional basis of Sp110-mediated macrophage resistance to Mtb, but also suggest potential regulatory roles for Sp110 related to inflammatory responses, miRNA profiles, and the intracellular growth of Mtb.

Effect of orally administered dipterinyl calcium pentahydrate on oral glucose tolerance in diet-induced obese mice

Calcium pterins have been shown to be significant immunotherapeutic agents in models of breast cancer, hepatitis B, and tuberculosis (Bacillus Calmette-Guérin mycobacteria). These compunds modulate the immuno-enzyme indoleamine 2,3-dioxygenase (IDO) and the blood levels of several identified inflammatory cytokines. Recent research into the pathology of diabetes implicates inflammatory factors in the progression of the disease, leading the authors to study its possible control by one of the calcium pterins, dipterinyl calcium pentahydrate (DCP). The investigators tested DCP as a novel therapeutic for type 2 diabetes. Female C57BL/6 J mice with diet-induced obesity were fed a high-fat diet and were administered DCP in 0.4% carboxymethylcellulose for 21 days. Blood glucose was followed during the dosing period, and an oral glucose tolerance test (OGTT) was carried out on day 21. Measurements of plasma indoleamine 2,3-dioxygenase metabolites (tryptophan and kynurenine) and certain cytokines and chemokines were also taken. DCP 7 mg/kg/day reduced OGTT area under the curve (OGTT/ AUC) by 50% (P < 0.05). A significant multivariate regression (P = 0.013; R(2) = 0.571) of OGTT/ AUC was derived from DCP dosage and plasma Trp. Elevated plasma Trp concentration, likely from heterogeneity in diet and/or indoleamine 2,3-dioxygenase activity, was found to correlate with higher OGTT/AUC diabetic measures, possibly via inhibition of histamine degradation. In conclusion, an optimum dose of DCP 7 mg/kg/day significantly improved the OGTT diabetic state in these female diet-induced obese mice.