Sonic hedgehog-dependent induction of microRNA 31 and microRNA 150 regulates Mycobacterium bovis BCG-driven toll-like receptor 2 signaling

Interaction between immuno-stem dual lineages in jaw bone formation and injury repair

The jawbone, a unique structure in the human body, undergoes faster remodeling than other bones due to the presence of stem cells and its distinct immune microenvironment. Long-term exposure of jawbones to an oral environment rich in microbes results in a complex immune balance, as shown by the higher proportion of activated macrophage in the jaw. Stem cells derived from the jawbone have a higher propensity to differentiate into osteoblasts than those derived from other bones. The unique immune microenvironment of the jaw also promotes osteogenic differentiation of jaw stem cells. Here, we summarize the various types of stem cells and immune cells involved in jawbone reconstruction. We describe the mechanism relationship between immune cells and stem cells, including through the production of inflammatory bodies, secretion of cytokines, activation of signaling pathways, etc. In addition, we also comb out cellular interaction of immune cells and stem cells within the jaw under jaw development, homeostasis maintenance and pathological conditions. This review aims to eclucidate the uniqueness of jawbone in the context of stem cell within immune microenvironment, hopefully advancing clinical regeneration of the jawbone.

Differential Expression of miR-146 and miR-155 in Active and Latent Tuberculosis Infection

Background

Tuberculosis (TB) is one of the leading causes of death worldwide. Besides, one-third of the world population is infected with Mycobacterium tuberculosis (MTB) while staying clinically asymptomatic; the situation is called latent TB infection (LTBI). MiR-21, miR-31, miR-146a, and miR-155 play an important role in many immune and inflammatory pathways. In the present study the expression levels of MiR-21, miR-31, miR-146a, and miR-155 in peripheral blood mononuclear cells (PBMCs) from patients with active TB, latently infected individuals (LTBI), and healthy controls (HC) were investigated. Participants were recruited at the Bouali Hospital, Zahedan University of Medical Sciences, Zahedan, Iran from 2010 to 2011.

Methods

PBMCs were stimulated with PPD before RNA extraction. TaqMan RT-qPCR assay was used to analyze the expression levels of miRNAs.

Results

The results indicated no significant differences in the expression of miR-21 and miR-31 between different groups; however, in patients with active TB, the expression of miR-21 (P=0.03) and miR-31 (P=0.04) were significantly increased after stimulation with PPD compared to the unstimulated condition. The expression of miR-146 in response to PPD in both LTBI (P=0.02) and TB (P=0.03) groups compared to the HC group was increased. No significant differences were found in the expression level of miR-155 in response to PPD between LTBI and HC groups. However, the fold change was significantly higher in the TB group in comparison with the HC (P=0.03) and LTBI (P=0.05) groups.

Conclusion

The results confirm the main role of miR-146 and miR-155 in TB infection and suggest a role for miR-146 and miR-155 as infection and activation markers in tuberculosis infection, respectively.

Therapeutic implication of Sonic Hedgehog as a potential modulator in ischemic injury

Sonic Hedgehog (SHh) is a homology protein that is involved in the modeling and development of embryonic tissues. As SHh plays both protective and harmful roles in ischemia, any disruption in the transduction and regulation of the SHh signaling pathway causes ischemia to worsen. The SHh signal activation occurs when SHh binds to the receptor complex of Ptc-mediated Smoothened (Smo) (Ptc-smo), which initiates the downstream signaling cascade. This article will shed light on how pharmacological modifications to the SHh signaling pathway transduction mechanism alter ischemic conditions via canonical and non-canonical pathways by activating certain downstream signaling cascades with respect to protein kinase pathways, angiogenic cytokines, inflammatory mediators, oxidative parameters, and apoptotic pathways. The canonical pathway includes direct activation of interleukins (ILs), angiogenic cytokines like hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and hypoxia-inducible factor alpha (HIF-), which modulate ischemia. The non-canonical pathway includes indirect activation of certain pathways like mTOR, PI3K/Akt, MAPK, RhoA/ROCK, Wnt/-catenin, NOTCH, Forkhead box protein (FOXF), Toll-like receptors (TLR), oxidative parameters such as GSH, SOD, and CAT, and some apoptotic parameters such as Bcl2. This review provides comprehensive insights that contribute to our knowledge of how SHh impacts the progression and outcomes of ischemic injuries.

MicroRNAs as diagnostic biomarkers for Tuberculosis: A systematic review and meta- analysis

Background

The early diagnosis of tuberculosis using novel non-sputum-based biomarkers is of high priority in the End TB strategy. MicroRNAs (miRNAs) are significant regulators of TB pathogenesis and their differential expression pattern among healthy, latent, and active TB population has revealed their potentiality as biomarkers in recent studies. Thus, we systematically reviewed and performed a meta-analysis on the role of host miRNAs in TB diagnosis. We also reviewed the involvement of miRNAs in the immune response to Mycobacterium tuberculosis (Mtb).

Methods

Pubmed, Ovid and Cochrane databases were searched to retrieve published literature from 2000 to 2020 using predefined keywords. We screened relevant studies based on inclusion and exclusion criteria and the included studies were assessed for their quality using STARD guidelines and QUADAS-2 tool. Funnel plots were constructed to assess the publication bias. The heterogeneity of studies and overall pooled results of sensitivity, specificity and DOR were determined using forest plots.

Results

We retrieved a total of 447 studies collectively from all the databases, out of which 21 studies were included for qualitative analysis. In these studies, miR-29, miR-31, miR-125b, miR146a and miR-155 were consistently reported. The overall sensitivity, specificity and DOR of these miRNAs were found to be 87.9% (81.7-92.2), 81.2% (74.5-86.5) and 43.1(20.3-91.3) respectively. Among these, miR-31 had the maximum diagnostic accuracy, with a sensitivity of 96% (89.7-98.5), specificity of 89% (81.2-93.8) and DOR of 345.9 (90.2-1326.3), meeting the minimal target product profile (TPP) for TB diagnostics.

Conclusion

miRNAs can thus be exploited as potential biomarkers for rapid detection of tuberculosis as evident from their diagnostic performance.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021226559 PROSPERO (CRD42021226559).

Human M1 macrophages express unique innate immune response genes after mycobacterial infection to defend against tuberculosis

Mycobacterium tuberculosis (Mtb) is responsible for approximately 1.5 million deaths each year. Though 10% of patients develop tuberculosis (TB) after infection, 90% of these infections are latent. Further, mice are nearly uniformly susceptible to Mtb but their M1-polarized macrophages (M1-MΦs) can inhibit Mtb in vitro, suggesting that M1-MΦs may be able to regulate anti-TB immunity. We sought to determine whether human MΦ heterogeneity contributes to TB immunity. Here we show that IFN-γ-programmed M1-MΦs degrade Mtb through increased expression of innate immunity regulatory genes (Inregs). In contrast, IL-4-programmed M2-polarized MΦs (M2-MΦs) are permissive for Mtb proliferation and exhibit reduced Inregs expression. M1-MΦs and M2-MΦs express pro- and anti-inflammatory cytokine-chemokines, respectively, and M1-MΦs show nitric oxide and autophagy-dependent degradation of Mtb, leading to increased antigen presentation to T cells through an ATG-RAB7-cathepsin pathway. Despite Mtb infection, M1-MΦs show increased histone acetylation at the ATG5 promoter and pro-autophagy phenotypes, while increased histone deacetylases lead to decreased autophagy in M2-MΦs. Finally, Mtb-infected neonatal macaques express human Inregs in their lymph nodes and macrophages, suggesting that M1 and M2 phenotypes can mediate immunity to TB in both humans and macaques. We conclude that human MФ subsets show unique patterns of gene expression that enable differential control of TB after infection. These genes could serve as targets for diagnosis and immunotherapy of TB.

MicroRNA and Gut Microbiota: Tiny but Mighty-Novel Insights into Their Cross-talk in Inflammatory Bowel Disease Pathogenesis and Therapeutics

MicroRNAs [miRNAs], small non-coding RNAs, have recently been described as crucial contributors to intestinal homeostasis. They can interact with the gut microbiota in a reciprocal manner and deeply affect host health status, leading to several disorders when unbalanced. Inflammatory bowel disease [IBD] is a chronic inflammation of the gastrointestinal tract that co-occurs with alterations of the gut microbiota, and whose aetiology remains largely unclear. On one hand, host miRNA could be playing a relevant role in IBD pathophysiology by shaping the gut microbiota. The gut microbiome, on the other hand, may regulate the expression of host miRNAs, resulting in intestinal epithelial dysfunction, altered autophagy, and immune hyperactivation. Interestingly, it has been hypothesised that their reciprocal impact may be used for therapeutic goals. This review describes the latest research and suggests mechanisms through which miRNA and intestinal microbiota, as joint actors, may participate specifically in IBD pathophysiology. Furthermore, we discuss the diagnostic power and therapeutic potential resulting from their bidirectional communication after faecal transplantation, probiotics intake, or anti-miRNAs or miRNA mimics administration. The current literature is summarised in the present work in a comprehensive manner, hoping to provide a better understanding of the miRNA-microbiota cross-talk and to facilitate their application in IBD.

miR-495 Regulates Cellular Reactive Oxygen Species Levels by Targeting sod2 To Inhibit Intracellular Survival of Mycobacterium tuberculosis in Macrophages

Mycobacterium tuberculosis is a chronic infectious disease pathogen. To date, tuberculosis is a major infectious disease that endangers human health. To better prevent and treat tuberculosis, it is important to study the pathogenesis of M. tuberculosis. Based on early-stage laboratory research results, in this study, we verified the upregulation of sod2 in Bacillus Calmette-Guérin (BCG) and H37Rv infection. By detecting BCG/H37Rv intracellular survival in sod2-silenced and sod2-overexpressing macrophages, sod2 was found to promote the intracellular survival of BCG/H37Rv. miR-495 then was determined to be downregulated by BCG/H37Rv. BCG/H37Rv can upregulate sod2 expression by miR-495 to promote the intracellular survival of BCG/H37Rv through a decline in ROS levels. This study provides a theoretical basis for developing new drug targets and treating tuberculosis.

Liquiritin reduces lipopolysaccharide-aroused HaCaT cell inflammation damage via regulation of microRNA-31/MyD88

BACKGROUND

Pressure ulcers are a common issue for people who have limited mobility. This study tested the impact of liquiritin on human keratinocyte HaCaT cell inflammatory damage aroused by lipopolysaccharide (LPS).

METHODS

HaCaT cells were underwent LPS and/or liquiritin incubation. Cell viability, apoptosis and inflammatory molecules interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and cyclooxygenase-2 (Cox-2) expressions, along with nuclear factor kappa B (NF-κB) and c-Jun N-terminal kinase (JNK) pathways activities were tested by MTT assay, Guava Nexin assay, ELISA and western blotting, respectively. qRT-PCR was done for measuring microRNA-31 (miR-31) expression. miR-31 inhibitor was transfected to silence miR-31. Animal pressure ulcers was established on the dorsal skin of adult rats. The effects of liquiritin on wound healing were analyzed by measuring wound closure rates.

RESULTS

LPS aroused HaCaT cell inflammatory damage, as evidenced by the decrease of cell viability, increase of cell apoptosis and enhanced expressions of IL-6, TNF-α and Cox-2. Liquiritin protected HaCaT cells against LPS-aroused inflammatory damage through increasing cell viability, decreasing cell apoptosis, and reducing IL-6, TNF-α and Cox-2 expressions. Liquiritin attenuated the LPS-aroused NF-κB and JNK pathways activation in HaCaT cells. Rat pressure ulcers model also confirmed that liquiritin promoted wound healing. In mechanism, miR-31 expression was boosted by liquiritin in HaCaT cells. Silencing miR-31 weakened the impacts of liquiritin on LPS-irritated HaCaT cells. Myeloid differentiation factor 88 (MyD88) was a target of miR-31 in HaCaT cells.

CONCLUSION

This research affirmed the beneficial impact of liquiritin on pressure ulcers. Liquiritin reduced LPS-aroused HaCaT cell inflammatory damage might be implemented via raising miR-31 expression, lowering MyD88 expression, and repressing NF-κB and JNK pathways.

Metabolic Fate of Human Immunoactive Sterols in Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) infection is among top ten causes of death worldwide, and the number of drug-resistant strains is increasing. The direct interception of human immune signaling molecules by Mtb remains elusive, limiting drug discovery. Oxysterols and secosteroids regulate both innate and adaptive immune responses. Here we report a functional, structural, and bioinformatics study of Mtb enzymes initiating cholesterol catabolism and demonstrated their interrelation with human immunity. We show that these enzymes metabolize human immune oxysterol messengers. Rv2266 - the most potent among them - can also metabolize vitamin D3 (VD3) derivatives. High-resolution structures show common patterns of sterols binding and reveal a site for oxidative attack during catalysis. Finally, we designed a compound that binds and inhibits three studied proteins. The compound shows activity against Mtb H37Rv residing in macrophages. Our findings contribute to molecular understanding of suppression of immunity and suggest that Mtb has its own transformation system resembling the human phase I drug-metabolizing system.

Systematic evaluation, verification and comparison of tuberculosis-related non-coding RNA diagnostic panels

We systematically summarized tuberculosis (TB)‐related non‐coding RNA (ncRNA) diagnostic panels, validated and compared panel performance. We searched TB‐related ncRNA panels in PubMed, OVID and Web of Science up to 28 February 2020, and available datasets in GEO, SRA and EBI ArrayExpress up to 1 March 2020. We rebuilt models and synthesized the results of each model in validation sets by bivariate mixed models. Specificity at 90% sensitivity, area under curve (AUC) and inconsistence index (I²) were calculated. NcRNA biofunctions were analysed. Nineteen models based on 18 ncRNA panels (miRNA, lncRNA, circRNA and snoRNA panels) and 18 datasets were included. Limited available datasets only allowed to evaluate miRNA panels further. Cui 2017 and Latorre 2015 exhibited specificity >70% at 90% sensitivity and AUC >80% in all validation sets. Cui 2017 showed higher specificity at 90% sensitivity (92%) and AUC (95%) and lower heterogeneity (I² = 0%) in ethological‐confirmation validation sets. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that most ncRNAs in panels involved in immune cell activation, oxidative stress, and Wnt and MAPK signalling pathway. Cui 2017 outperformed other models in both all available and aetiological‐confirmed validation sets, meeting the criteria of target product profile of WHO. This work provided a basis for clinical choice of TB‐related ncRNA diagnostic panels to a certain extent.

MicroRNA-23a-3p Down-Regulation in Active Pulmonary Tuberculosis Patients with High Bacterial Burden Inhibits Mononuclear Cell Function and Phagocytosis through TLR4/TNF-α/TGF-β1/IL-10 Signaling via Targeting IRF1/SP1

The aim of this study is to explore the role of microRNAs (miR)-21/23a/146a/150/155 targeting the toll-like receptor pathway in active tuberculosis (TB) disease and latent TB infection (LTBI). Gene expression levels of the five miRs and predicted target genes were assessed in peripheral blood mononuclear cells from 46 patients with active pulmonary TB, 15 subjects with LTBI, and 17 non-infected healthy subjects (NIHS). THP-1 cell lines were transfected with miR-23a-3p mimics under stimuli with Mycobacterium TB-specific antigens. Both miR-155-5p and miR-150-5p gene expressions were decreased in the active TB group versus the NIHS group. Both miR-23a-3p and miR-146a-5p gene expressions were decreased in active TB patients with high bacterial burden versus those with low bacterial burden or control group (LTBI + NIHS). TLR2, TLR4, and interleukin (IL)10 gene expressions were all increased in active TB versus NIHS group. MiR-23a-3p mimic transfection reversed ESAT6-induced reduction of reactive oxygen species generation, and augmented ESAT6-induced late apoptosis and phagocytosis, in association with down-regulations of the predicted target genes, including tumor necrosis factor (TNF)-α, TLR4, TLR2, IL6, IL10, Notch1, IL6R, BCL2, TGF-β1, SP1, and IRF1. In conclusion, the down-regulation of miR-23a-3p in active TB patients with high bacterial burden inhibited mononuclear cell function and phagocytosis through TLR4/TNF-α/TGF-β1/IL-10 signaling via targeting IRF1/SP1.

The role of non-coding RNA on macrophage modification in tuberculosis infection

Tuberculosis (TB), a serious disease caused by Mycobacterium tuberculosis (Mtb), remains the world's top infectious killer. It is well-established that TB can circumvent the host's immune response for long-term survival. Macrophages serve as the major host cells for TB growth and persistence and their altered functions are critical for the response of the host defense against TB exposure (elimination, latency, reactivation, and bacillary dissemination). Noncoding RNAs are crucial posttranscriptional regulators of macrophage discrimination. Therefore, this review highlights the regulatory mechanism underlying the relationship between noncoding RNAs and macrophages in TB infection, which may facilitate the identification of potential therapeutic targets and effective diagnosis biomarkers for TB disease.

MiRNAs in tuberculosis: Their decisive role in the fate of TB

Tuberculosis (TB) is one of the most lethal global infectious diseases. Despite the availability of much higher levels of technology in health and medicine, tuberculosis still remains a serious global health problem. Mycobacterium tuberculosis has the capacity for prolonged survival inside macrophages by exploiting host metabolic and energy pathways and perturbing autophagy and apoptosis of infected cells. The mechanism(s) underlying this process are not completely understood but evidence suggests that mycobacteria subvert the host miRNA network to enable mycobacterial survival. We present here a comprehensive review on the role of miRNAs in TB immune escape mechanisms and the potential for miRNA-based TB therapeutics. Further validation studies are required to (i) elucidate the precise effect of TB on host miRNAs, (ii) determine the inhibition of mycobacterial burden using miRNA-based therapies and (iii) identify novel miRNA biomarkers that may prove useful in TB diagnosis and treatment monitoring.

Targeting redox heterogeneity to counteract drug tolerance in replicating Mycobacterium tuberculosis

The capacity of Mycobacterium tuberculosis (Mtb) to tolerate multiple antibiotics represents a major problem in tuberculosis (TB) management. Heterogeneity in Mtb populations is one of the factors that drives antibiotic tolerance during infection. However, the mechanisms underpinning this variation in bacterial population remain poorly understood. Here, we show that phagosomal acidification alters the redox physiology of Mtb to generate a population of replicating bacteria that display drug tolerance during infection. RNA sequencing of this redox-altered population revealed the involvement of iron-sulfur (Fe-S) cluster biogenesis, hydrogen sulfide (H₂S) gas, and drug efflux pumps in antibiotic tolerance. The fraction of the pH- and redox-dependent tolerant population increased when Mtb infected macrophages with actively replicating HIV-1, suggesting that redox heterogeneity could contribute to high rates of TB therapy failure during HIV-TB coinfection. Pharmacological inhibition of phagosomal acidification by the antimalarial drug chloroquine (CQ) eradicated drug-tolerant Mtb, ameliorated lung pathology, and reduced postchemotherapeutic relapse in in vivo models. The pharmacological profile of CQ (C _max and AUC_last) exhibited no major drug-drug interaction when coadministered with first line anti-TB drugs in mice. Our data establish a link between phagosomal pH, redox metabolism, and drug tolerance in replicating Mtb and suggest repositioning of CQ to shorten TB therapy and achieve a relapse-free cure.

Expression levels of candidate circulating microRNAs in pediatric tuberculosis

Tuberculosis (TB) is a preventable and curable disease, but increased mortality and morbidity associated with TB is one of the leading causes of deaths worldwide. MicroRNAs (miRNAs) are small, non-coding RNAs known to regulate the host immune response against TB. We investigated the expression profile of candidate circulating miRNAs, which could be used as a blood biomarker for the effective diagnosis of pediatric tuberculosis. A cross-sectional comparative study was conducted, including 30 children with active-TB and 30 healthy controls (HC) in a tertiary care hospital in Puducherry. We used the SYBR green-based miScript qRT-PCR assay to analyze the expression levels of miRNAs in plasma. Further, we used the receiver operating characteristic curve (ROC) to evaluate the diagnostic value of miRNAs. Active-TB included 25 (83.3%) pulmonary TB and 5 (16.7%) extrapulmonary TB cases. We found a significant upregulation of miR-21, miR-29a, miR-31, miR-155, and downregulation of miR-146a in children with active-TB compared to HC. The ROC analysis showed an excellent diagnostic value of miRNAs as follows: miR‑31> miR‑155> miR‑146a with AUC of (95% CI) miRNAs 0.978, 0.953, and 0.903, respectively. Altered circulating miRNA expression levels could be involved in the dysregulation of the host immune response to TB. The ROC analysis indicated that miRNAs miR-31, miR-155 and miR-146a could be effective diagnostic biomarkers for the detection of active-TB in children.

Circular RNA ANKRD36 attends to lipopolysaccharide-aroused MRC-5 cell injury via regulating microRNA-31-3p

BACKGROUND

Some circular RNAs (circRNAs) are reported to attend to the pathogenesis of pneumonia. This study tested the impact of circRNA ankyrin repeat domain 36 (circANKRD36) on human embryonic lung fibroblast MRC-5 cell injury irritated by lipopolysaccharide (LPS).

METHODS

After LPS irritation, viability, apoptosis, ROS, protein, and cytokines, along with circANKRD36 were tested by CCK-8, Annexin V-FITC, DCFH-DA, and ELISA or Western blot. si-circANKRD36 and microRNA-31-3p/5p (miR-31-3p/5p) inhibitor were applied to silence circANKRD36 and miR-31-3p/5p. miR-31-3p/5p mimic was utilized to upregulate miR-31-3p/5p. RT-qPCR was used to detect miRNAs. The relationship between miRNAs and MyD88 or IL-34 was analyzed by luciferase activity reporter assay.

RESULTS

LPS aroused a decrease in viability, increases in apoptosis, ROS, and IL-6, IL-8, and TNF-α, along with circANKRD36, and activation of NF-κB pathway. Silencing circANKRD36 weakened the above-mentioned influences of LPS. Moreover, silencing circANKRD36 hoisted miR-31-3p expression. Silencing miR-31-3p mitigated the impacts of circANKRD36 silence on LPS-irritated MRC-5 cells. Besides, MyD88 was a downstream target of miR-31-3p, and 3'UTR of IL-34 mRNA was targeted by miR-31-5p. LPS induced the accumulation of MyD88. Silencing MyD88 was constructive to maintain cell viability, retard apoptosis and inhibit adverse oxidation and inflammation.

CONCLUSION

This research verified that silencing circANKRD36 could weaken LPS-irritated MRC-5 cell injury via regulating miR-31/MyD88-mediated repression of NF-κB pathway.

Bacterial RNA in extracellular vesicles: A new regulator of host-pathogen interactions?

Extracellular vesicles (EVs) are released by cells from all kingdoms and represent one form of cell-cell interaction. This universal system of communication blurs cells type boundaries, offering an new avenue for pathogens to infect their hosts. EVs carry with them an arsenal of virulence factors that have been the focus of numerous studies. During the last years, the RNA content of EVs has also gained increasing attention, particularly in the context of infection. Secreted RNA in EVs (evRNA) from several bacterial pathogens have been characterised but the exact mechanisms promoting pathogenicity remain elusive. In this review, we evaluate the potential of such transcripts to directly interact with targets in infected cells and, by this, represent a novel angle of host cell manipulation during bacterial infection. This article is part of a Special Issue entitled: RNA and gene control in bacteria edited by Dr. M. Guillier and F. Repoila.

Minocycline Immunomodulates via Sonic Hedgehog Signaling and Apoptosis and Has Direct Potency Against Drug-Resistant Tuberculosis

Drug-resistant tuberculosis represents a global emergency, requiring new drugs. We found that minocycline was highly potent in laboratory strains of Mycobacterium tuberculosis and that 30 drug-susceptible and multidrug/extensively drug-resistant clinical strains were susceptible to clinically achievable concentrations. In the hollow fiber system model, lung concentration-time profiles of 7 mg/kg/day human-equivalent minocycline dose achieved bacterial kill rates equivalent to those of first-line antituberculosis agents. Minocycline killed extracellular bacilli directly. Minocycline also killed intracellular bacilli indirectly, via concentration-dependent granzyme A-driven apoptosis. Moreover, minocycline demonstrated dose-dependent antiinflammatory activity and downregulation of extracellular matrix-based remodeling pathways and, thus, could protect patients from tuberculosis immunopathology. In RNA sequencing of repetitive samples from the hollow fiber system and in independent protein abundance experiments, minocycline demonstrated dose-dependent inhibition of sonic hedgehog-patched-gli signaling. These findings have implications for improved lung remodeling and for dual immunomodulation and direct microbial kill-based treatment shortening regimens for drug-susceptible and drug-resistant latent and active M. tuberculosis infection.

microRNAs in Mycobacterial Infection: Modulation of Host Immune Response and Apoptotic Pathways

Our current knowledge of mycobacterial infections in humans has progressively increased over the past few decades. The infection of Mycobacterium tuberculosis causes tuberculosis (TB) disease, which has reasoned for excessive morbidity and mortality worldwide, and has become a foremost issue of health problem globally. Mycobacterium leprae, another member of the family Mycobacteriaceae, is responsible for causing a chronic disease known as leprosy that mainly affects mucosa of the upper respiratory tract, skin, peripheral nerves, and eyes. Ample amount of existing data suggests that pathogenic mycobacteria have skilled in utilizing different mechanisms to escape or offset the host immune responses. They hijack the machinery of immune cells through the modulation of microRNAs (miRs), which regulate gene expression and immune responses of the host. Evidence shows that miRs have now gained considerable attention in the research, owing to their involvement in a broad range of inflammatory processes that are further implicated in the pathogenesis of several diseases. However, the knowledge of functions of miRs during mycobacterial infections remains limited. This review summarises recent findings of differential expression of miRs, which are used to good advantage by mycobacteria in offsetting host immune responses generated against them.

Analysis of the microRNA Expression Profile of Bovine Monocyte-derived Macrophages Infected with Mycobacterium avium subsp. Paratuberculosis Reveals that miR-150 Suppresses Cell Apoptosis by Targeting PDCD4

M. avium subsp. paratuberculosis (MAP) is the causative pathogen of Johne’s disease, a chronic granulomatous enteritis that principally affects ruminants and can survive, proliferate and disseminate in macrophages. MicroRNAs (miRNAs) are important regulators of gene expression and can impact the processes of cells. To investigate the role of miRNAs in monocyte-derived macrophages (MDMs) during MAP infection, we used high-throughput sequencing technology to analyze small RNA libraries of MAP-infected and control MDMs. The results showed that a total of 21 miRNAs were differentially expressed in MDMs after MAP infection, and 8864 target genes were predicted. A functional analysis showed that the target genes were mainly involved in the MAPK signaling pathway, Toll-like receptor signaling pathway, NF-kappa B signaling pathway and apoptosis. In addition, using a dual-luciferase reporter assay, flow cytometry, and a small interfering (si)RNA knockdown assay, the role of miR-150 in regulating macrophage apoptosis by targeting the programmed cell death protein-4 (PDCD4) was demonstrated. These results provide an experimental basis to reveal the regulatory mechanism of MAP infection and suggest the potential of miRNAs as biomarkers for the diagnosis of Johne’s disease in bovines.

Clinical significance of lnc-AC145676.2.1-6 and lnc-TGS1-1 and their variants in western Chinese tuberculosis patients

OBJECTIVES

Tuberculosis (TB) remains a global public health problem. Recent studies have implicated long non-coding RNAs and their variants as possibly playing important roles in TB. The aim of this study was to assess the clinical relevance of lnc-AC145676.2.1-6 and lnc-TGS1-1 and their variants in a western Chinese population.

METHODS

This case-control study included 467 TB patients and 473 healthy controls from West China Hospital. The expression levels of lnc-AC145676.2.1-6 and lnc-TGS1-1 were analyzed by reverse transcriptase quantitative real-time PCR. Single-nucleotide polymorphism genotyping was performed using a custom-designed 2 × 48-Plex SNPscan kit.

RESULTS

It was observed that lnc-AC145676.2.1-6 and lnc-TGS1-1 expression levels were both obviously down-regulated in TB patients. In addition, a lower expression level of lnc-TGS1-1 was associated with the presence of thrombocytopenia in TB patients during anti-TB treatment, and the homozygous CC genotype of rs4737420 correlated with a decreased risk of leukopenia, compared with individuals with the T allele (TT/CT genotype), in the dominant mode.

CONCLUSIONS

For the first time, potential TB-associated promoting effects were identified for the decreased expression levels of lnc-AC145676.2.1-6 and lnc-TGS-1, while lnc-TGS1-1 and its variant rs4737420 may be predictive indicators of anti-TB drug-induced adverse drug reactions. Larger validation studies on different populations are warranted to confirm these findings.

Upregulation of Helicoverpa armigera core RNA interference genes by bacterial infections and its effect on the insect-bacteria interaction

RNA interference (RNAi) is an extremely conserved defence mechanism. The antiviral role of the RNAi pathway in insects is well documented; however, the relevance of this pathway in other aspects of insect immunity is largely unknown. In this study, we questioned whether RNAi has any function during insect-bacteria interactions. For this, we assessed induction of the RNAi pathway in response to bacterial infections by monitoring the expression of dicer1/argonaute1 and dicer2/argonaute2, which are important genes in the microRNA and short interfering RNA sub-pathways respectively. Bacterial cells of Bacillus thuringiensis and Serratia marcescens were injected into the haemocoel of fifth-instar larvae of Helicoverpa armigera, whereas double-distilled water was injected into control insects. Expression levels of the RNAi-related genes increased in the bacteria-injected larvae compared with controls. Transcript knockdown of dicer1 reduced the replication of B. thuringiensis; as a consequence, larval mortality decreased compared with the control. However, replication of S. marcescens increased following dicer1 silencing, which led to higher rates of larval mortality when compared with the control. RNAi of dicer2 promoted replication of both bacteria in the larvae and also enhanced larval mortality. Therefore, dicer1 and dicer2 affected larval survival and the replication rates of the pathogenic bacteria, suggesting their roles in the interactions.

Deregulated AUF1 Assists BMP-EZH2-Mediated Delayed Wound Healing during Candida albicans Infection

Tissue repair is a complex process that necessitates an interplay of cellular processes, now known to be dictated by epigenetics. Intriguingly, macrophages are testimony to a large repertoire of evolving functions in this process. We identified a role for BMP signaling in regulating macrophage responses to Candida albicans infection during wound repair in a murine model. In this study, the RNA binding protein, AU-rich element-binding factor 1, was posttranslationally destabilized to bring about ubiquitin ligase, NEDD4-directed activation of BMP signaling. Concomitantly, PI3K/PKCδ mobilized the rapid phosphorylation of BMP-responsive Smad1/5/8. Activated BMP pathway orchestrated the elevated recruitment of EZH2 at promoters of genes assisting timely wound closure. In vivo, the repressive H3K27 trimethylation was observed to persist, accompanied by a robust upregulation of BMP pathway upon infection with C. albicans, culminating in delayed wound healing. Altogether, we uncovered the signaling networks coordinated by fungal colonies that are now increasingly associated with the infected wound microbiome, resulting in altered wound fate.

A miRNA Host Response Signature Accurately Discriminates Acute Respiratory Infection Etiologies

Background: Acute respiratory infections (ARIs) are the leading indication for antibacterial prescriptions despite a viral etiology in the majority of cases. The lack of available diagnostics to discriminate viral and bacterial etiologies contributes to this discordance. Recent efforts have focused on the host response as a source for novel diagnostic targets although none have explored the ability of host-derived microRNAs (miRNA) to discriminate between these etiologies. Methods: In this study, we compared host-derived miRNAs and mRNAs from human H3N2 influenza challenge subjects to those from patients with Streptococcus pneumoniae pneumonia. Sparse logistic regression models were used to generate miRNA signatures diagnostic of ARI etiologies. Generalized linear modeling of mRNAs to identify differentially expressed (DE) genes allowed analysis of potential miRNA:mRNA relationships. High likelihood miRNA:mRNA interactions were examined using binding target prediction and negative correlation to further explore potential changes in pathway regulation in response to infection. Results: The resultant miRNA signatures were highly accurate in discriminating ARI etiologies. Mean accuracy was 100% [88.8-100; 95% Confidence Interval (CI)] in discriminating the healthy state from S. pneumoniae pneumonia and 91.3% (72.0-98.9; 95% CI) in discriminating S. pneumoniae pneumonia from influenza infection. Subsequent differential mRNA gene expression analysis revealed alterations in regulatory networks consistent with known biology including immune cell activation and host response to viral infection. Negative correlation network analysis of miRNA:mRNA interactions revealed connections to pathways with known immunobiology such as interferon regulation and MAP kinase signaling. Conclusion: We have developed novel human host-response miRNA signatures for bacterial and viral ARI etiologies. miRNA host response signatures reveal accurate discrimination between S. pneumoniae pneumonia and influenza etiologies for ARI and integrated analyses of the host-pathogen interface are consistent with expected biology. These results highlight the differential miRNA host response to bacterial and viral etiologies of ARI, offering new opportunities to distinguish these entities.

miRNAs reshape immunity and inflammatory responses in bacterial infection

Pathogenic bacteria cause various infections worldwide, especially in immunocompromised and other susceptible individuals, and are also associated with high infant mortality rates in developing countries. MicroRNAs (miRNAs), small non-coding RNAs with evolutionarily conserved sequences, are expressed in various tissues and cells that play key part in various physiological and pathologic processes. Increasing evidence implies roles for miRNAs in bacterial infectious diseases by modulating inflammatory responses, cell penetration, tissue remodeling, and innate and adaptive immunity. This review highlights some recent intriguing findings, ranging from the correlation between aberrant expression of miRNAs with bacterial infection progression to their profound impact on host immune responses. Harnessing of dysregulated miRNAs in bacterial infection may be an approach to improving the diagnosis, prevention and therapy of infectious diseases.

Changes in production of tiny cellular RNAs in response to bacterial infection could guide the development of better diagnostics and therapies. MicroRNAs regulate other genes by binding to messenger RNA strands and controlling their translation into proteins. Xikun Zhou, Min Wu and colleagues of the University of North Dakota have now reviewed current knowledge about how microRNA levels shift during infection with various bacterial pathogens. These microRNAs can modulate the immune response as well as pathways that influence metabolic activity and cell survival. Increasing studies have indicated that shifts in microRNA levels in response to different infections could provide a potential bacterial ‘fingerprint’ for achieving accurate diagnosis. With deeper insight into how different microRNAs influence infection, it might one day day become possible to target these molecules with ‘antisense’ or ‘agonist’ drugs that modulate their activity.

Mycobacterium tuberculosis-induced miR-155 subverts autophagy by targeting ATG3 in human dendritic cells

Autophagy is a primordial eukaryotic pathway, which provides the immune system with multiple mechanisms for the elimination of invading pathogens including Mycobacterium tuberculosis (Mtb). As a consequence, Mtb has evolved different strategies to hijack the autophagy process. Given the crucial role of human primary dendritic cells (DC) in host immunity control, we characterized Mtb-DC interplay by studying the contribution of cellular microRNAs (miRNAs) in the post-transcriptional regulation of autophagy related genes. From the expression profile of de-regulated miRNAs obtained in Mtb-infected human DC, we identified 7 miRNAs whose expression was previously found to be altered in specimens of TB patients. Among them, gene ontology analysis showed that miR-155, miR-155* and miR-146a target mRNAs with a significant enrichment in biological processes linked to autophagy. Interestingly, miR-155 was significantly stimulated by live and virulent Mtb and enriched in polysome-associated RNA fraction, where actively translated mRNAs reside. The putative pair interaction among the E2 conjugating enzyme involved in LC3-lipidation and autophagosome formation-ATG3-and miR-155 arose by target prediction analysis, was confirmed by both luciferase reporter assay and Atg3 immunoblotting analysis of miR-155-transfected DC, which showed also a consistent Atg3 protein and LC3 lipidated form reduction. Late in infection, when miR-155 expression peaked, both the level of Atg3 and the number of LC3 puncta per cell (autophagosomes) decreased dramatically. In accordance, miR-155 silencing rescued autophagosome number in Mtb infected DC and enhanced autolysosome fusion, thereby supporting a previously unidentified role of the miR-155 as inhibitor of ATG3 expression. Taken together, our findings suggest how Mtb can manipulate cellular miRNA expression to regulate Atg3 for its own survival, and highlight the importance to develop novel therapeutic strategies against tuberculosis that would boost autophagy.

Mycobacterium tuberculosis (Mtb) is one of the most successful pathogens in human history and remains the second leading cause of death from an infectious agent worldwide. The major reason of Mtb success relies on its ability to evade host immunity. Autophagy, a cellular mechanism involved in intracellular pathogen elimination, is one of the pathways hijacked by Mtb to elude the control of dendritic cells (DC), major cellular effectors of immune response. Recently, it has become clear that Mtb infection not only alters cellular gene expression, but also controls the level of small RNA molecules, namely microRNAs (miRNAs), which function as negative regulators of mRNA translation into protein. In the present study, we observed that the infection of human DC with Mtb leads to a strong induction of host miR-155, a critical regulator of host immune response. By mean of miR-155 induction, Mtb reduces Atg3 protein content, a crucial enzyme needed for the initial phase of the autophagic process. Interestingly, miR-155 silencing during Mtb infection restores Atg3 level and rescues autophagy. These findings contribute to better elucidate Mtb-triggered escape mechanisms and highlight the importance to develop host-directed therapies to combat tuberculosis based on autophagy boosting.

Proof-of-concept study: profile of circulating microRNAs in Bovine serum harvested during acute and persistent FMDV infection

Background

Changes in the levels of circulating microRNAs (miRNAs) in the serum of humans and animals have been detected as a result of infection with a variety of viruses. However, to date, such a miRNA profiling study has not been conducted for foot-and-mouth disease virus (FMDV) infection.

Methods

The relative abundance of 169 miRNAs was measured in bovine serum collected at three different phases of FMDV infection in a proof-of-concept study using miRNA PCR array plates.

Results

Alterations in specific miRNA levels were detected in serum during acute, persistent, and convalescent phases of FMDV infection. Subclinical FMDV persistence produced a circulating miRNA profile distinct from cattle that had cleared infection. bta-miR-17-5p was highest expressed during acute infection, whereas bta-miR-31 was the highest during FMDV persistence. Interestingly, miR-1281was significantly down-regulated during both acute and persistent infection. Cattle that cleared infection resembled the baseline profile, adding support to applying serum miRNA profiling for identification of sub-clinically infected FMDV carriers. Significantly regulated miRNAs during acute or persistent infection were associated with cellular proliferation, apoptosis, modulation of the immune response, and lipid metabolism.

Conclusions

These findings suggest a role for non-coding regulatory RNAs in FMDV infection of cattle. Future studies will delineate the individual contributions of the reported miRNAs to FMDV replication, determine if this miRNA signature is applicable across all FMDV serotypes, and may facilitate development of novel diagnostic applications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0743-3) contains supplementary material, which is available to authorized users.

Cerebrospinal fluid from patients with amyotrophic lateral sclerosis inhibits sonic hedgehog function

Sonic hedgehog (Shh) is a morphogen essential to the developing nervous system that continues to play an important role in adult life by contributing to cell proliferation and differentiation, maintaining blood-brain barrier integrity, and being cytoprotective against oxidative and excitotoxic stress, all features of importance in amyotrophic lateral sclerosis (ALS). ALS is a fatal disease characterized by selective loss of motor neurons due to poorly understood mechanisms. Evidence indicates that Shh might play an important role in ALS, and that Shh signaling might be also adversely affected in ALS. Since little is known about the functional status of Shh pathway in patients with ALS, we therefore sought to determine whether Shh protein levels or biological activity in cerebrospinal fluid (CSF) was less in ALS patients than controls, and whether these measures could be correlated with ALS disease severity and disease progression, and with other CSF analytes of biological interest in ALS. Comparing Shh levels in the CSF of normal controls (n = 13), neurological controls (n = 12), and ALS patients (n = 9) measured by ELISA, we found that CSF Shh levels were not different between controls and ALS patients. However, when assessing Shh biological activity in CSF using in vitro cell-based assays, which measure Shh activity as inducible Gli-driven luminescence, we found that in the presence of exogenous recombinant Shh or the Shh agonist, purmorphamine, the inducible activity of CSF was significantly augmented in the control groups as expected, but not in the ALS group, suggesting the presence of an inhibitor of Shh signaling in ALS CSF samples. Since purmorphamine acts on Smoothened, downstream of Shh and its receptor Patched, the inhibitory action is downstream of Smoothened. Our results also demonstrated that while the inhibitory effect of ALS CSF on Shh signaling did not correlate significantly with ALS disease characteristics, the levels of IL-1β and TNF-α did. In addition to being significantly elevated in ALS CSF, these cytokines negatively correlated with the disease duration, whereas GDF11 was a favorable predictor of ALS clinical score. We also found that TNF-α significantly inhibited Shh biological activity in vitro, potentially suggesting a novel role of TNF-α in ALS pathogenesis. Collectively, this is the first report demonstrating that Shh signaling in CSF of ALS patients is compromised.

Mir-29a expressions in peripheral blood mononuclear cell and cerebrospinal fluid: Diagnostic value in patients with pediatric tuberculous meningitis

To evaluate the value of miR-29a expression in peripheral blood mononuclear cell (PBMC) and cerebrospinal fluid (CSF) in the diagnosis of pediatric tuberculous meningitis (TBM). Our study enrolled 112 children with TBM and 130 healthy children, from which PBMC and CSF were collected. The quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of miR-29a in PBMC and CSF, and then analyze the diagnostic value. Compared with control group, the miR-29a expressions in PBMC and CSF were increased in TBM children (both P<0.05), and the expressions were associated with following factors: intracranial hypertension, conscious disturbance, focal cerebral symptoms, meningeal irritation, hydrocrania, abnormal electroencephalogram and extra-cerebral tuberculous (all P<0.05). The receiver operating characteristic (ROC) curve showed that the sensitivity, specificity and area under the curve (AUC) of miR-29a in PBMC was 67.20%, 88.50% and 0.852, respectively, and that in CSF was 81.10%, 90.00% and 0.890, respectively, and that in combination of PBMC and CSF was 84.40%, 95.38% and 0.934, respectively. miR-29a expression in PBMC and CSF may provide a reference for the diagnosis of pediatric TBM.

Early alterations of Hedgehog signaling pathway in vascular endothelial cells after peripheral nerve injury elicit blood-nerve barrier disruption, nerve inflammation, and neuropathic pain development

Changes in the nerve's microenvironment and local inflammation resulting from peripheral nerve injury participate in nerve sensitization and neuropathic pain development. Taking part in these early changes, disruption of the blood-nerve barrier (BNB) allows for infiltration of immunocytes and promotes the neuroinflammation. However, molecular mechanisms engaged in vascular endothelial cells (VEC) dysfunction and BNB alterations remain unclear. In vivo, BNB permeability was assessed following chronic constriction injury (CCI) of the rat sciatic nerve (ScN) and differential expression of markers of VEC functional state, inflammation, and intracellular signaling was followed from 3 hours to 2 months postinjury. Several mechanisms potentially involved in functional alterations of VEC were evaluated in vitro using human VEC (hCMEC/D3), then confronted to in vivo physiopathological conditions. CCI of the ScN led to a rapid disruption of endoneurial vascular barrier that was correlated to a decreased production of endothelial tight-junction proteins and an early and sustained alteration of Hedgehog (Hh) signaling pathway. In vitro, activation of Toll-like receptor 4 in VEC downregulated the components of Hh pathway and altered the endothelial functional state. Inhibition of Hh signaling in the ScN of naive rats mimicked the biochemical and functional alterations observed after CCI and was, on its own, sufficient to evoke local neuroinflammation and sustained mechanical allodynia. Alteration of the Hh signaling pathway in VEC associated with peripheral nerve injury, is involved in BNB disruption and local inflammation, and could thus participate in the early changes leading to the peripheral nerve sensitization and, ultimately, neuropathic pain development.

Adjunct Strategies for Tuberculosis Vaccines: Modulating Key Immune Cell Regulatory Mechanisms to Potentiate Vaccination

Tuberculosis (TB) remains a global health threat of alarming proportions, resulting in 1.5 million deaths worldwide. The only available licensed vaccine, Bacillus Calmette–Guérin, does not confer lifelong protection against active TB. To date, development of an effective vaccine against TB has proven to be elusive, and devising newer approaches for improved vaccination outcomes is an essential goal. Insights gained over the last several years have revealed multiple mechanisms of immune manipulation by Mycobacterium tuberculosis (Mtb) in infected macrophages and dendritic cells that support disease progression and block development of protective immunity. This review provides an assessment of the known immunoregulatory mechanisms altered by Mtb, and how new interventions may reverse these effects. Examples include blocking of inhibitory immune cell coreceptor checkpoints (e.g., programed death-1). Conversely, immune mechanisms that strengthen immune cell effector functions may be enhanced by interventions, including stimulatory immune cell coreceptors (e.g., OX40). Modification of the activity of key cell “immunometabolism” signaling pathway molecules, including mechanistic target of rapamycin, glycogen synthase kinase-3β, wnt/β-catenin, adenosine monophosophate-activated protein kinase, and sirtuins, related epigenetic changes, and preventing induction of immune regulatory cells (e.g., regulatory T cells, myeloid-derived suppressor cells) are powerful new approaches to improve vaccine responses. Interventions to favorably modulate these components have been studied primarily in oncology to induce efficient antitumor immune responses, often by potentiation of cancer vaccines. These agents include antibodies and a rapidly increasing number of small molecule drug classes that have contributed to the dramatic immune-based advances in treatment of cancer and other diseases. Because immune responses to malignancies and to Mtb share many similar mechanisms, studies to improve TB vaccine responses using interventions based on “immuno-oncology” are needed to guide possible repurposing. Understanding the regulation of immune cell functions appropriated by Mtb to promote the imbalance between protective and pathogenic immune responses may guide the development of innovative drug-based adjunct approaches to substantially enhance the clinical efficacy of TB vaccines.

MicroRNA in innate immunity and autophagy during mycobacterial infection

The fine-tuning of innate immune responses is an important aspect of host defenses against mycobacteria. MicroRNAs (miRNAs), small non-coding RNAs, play essential roles in regulating multiple biological pathways including innate host defenses against various infections. Accumulating evidence shows that many miRNAs regulate the complex interplay between mycobacterial survival strategies and host innate immune pathways. Recent studies have contributed to understanding the role of miRNAs, the levels of which can be modulated by mycobacterial infection, in tuning host autophagy to control bacterial survival and innate effector function. Despite considerable efforts devoted to miRNA profiling over the past decade, further work is needed to improve the selection of appropriate biomarkers for tuberculosis. Understanding the roles and mechanisms of miRNAs in regulating innate immune signaling and autophagy may provide insights into new therapeutic modalities for host-directed anti-mycobacterial therapies. Here, we present a comprehensive review of the recent literature regarding miRNA profiling in tuberculosis and the roles of miRNAs in modulating innate immune responses and autophagy defenses against mycobacterial infections.

Mycobacterium tuberculosis-triggered Hippo pathway orchestrates CXCL1/2 expression to modulate host immune responses

Mycobacterium tuberculosis (Mtb) pathogenesis encompasses a plethora of finely regulated alterations within the host which eventually coin the outcome of infection. Chemokines are important components in directing immune cell recruitment to the site of infection, and shaping the disease progression. Here, we demonstrate that Hippo (mammalian sterile 20-like 1 and 2 kinases, MST1/2, in mammals), is activated during mycobacterial infection in a toll-like receptor (TLR) 2-interleukin receptor-1 associated kinases (IRAK1/4)-dependent manner. Mtb-triggered Hippo signaling modulates the expression and secretion of chemokines (CXCL1 and CXCL2); as silencing MST1/2 compromised the ability of Mtb to furnish the same. Further insight into the mechanism of Hippo-mediated regulation of chemokines revealed the role for a non-canonical Hippo effector interferon (IFN) regulatory factor (IRF) 3 in the process and marked the effect to be independent of LATS1. Alongside their ability to guide directed recruitment of immune cells, we have uncovered a paracrine role for Hippo-mediated secretion of CXCL1 and CXCL2 in the production of anti-microbial peptides (beta-defensins), iNOS, NOX2 and pro-inflammatory molecules during mycobacterial infection of the host. This study highlights the involvement of TLR2-IRAK1/4-MST1/2-IRF3 axis in Mtb-triggered modulation of chemokines and identifies Hippo signaling as a novel regulator of host-mycobacterial interactions.

MicroRNAs play big roles in modulating macrophages response toward mycobacteria infection

Macrophages are crucial player in the defense against multiple intracellular pathogens. Mycobacterium tuberculosis, the causative agent of tuberculosis which inflicted around one third of global population, can replicate and persist within macrophages. MicroRNAs, endogenous, small noncoding RNA, can regulate the expression of macrophages genes required for appropriate signaling. Mycobacteria can manipulate the expression of macrophages microRNAs to subvert cell response for its survival and persistence. This review summarized the progress of microRNAs in mycobacterial pathogenesis.

MUSASHI-Mediated Expression of JMJD3, a H3K27me3 Demethylase, Is Involved in Foamy Macrophage Generation during Mycobacterial Infection

Foamy macrophages (FM)s harbor lipid bodies that not only assist mycobacterial persistence within the granulomas but also are sites for intracellular signaling and inflammatory mediators which are essential for mycobacterial pathogenesis. However, molecular mechanisms that regulate intracellular lipid accumulation in FMs during mycobacterial infection are not clear. Here, we report for the first time that jumonji domain containing protein (JMJD)3, a demethylase of the repressive H3K27me3 mark, orchestrates the expression of M. tuberculosis H37Rv-, MDR-JAL2287-, H37Ra- and M. bovis BCG-induced genes essential for FM generation in a TLR2-dependent manner. Further, NOTCH1-responsive RNA-binding protein MUSASHI (MSI), targets a transcriptional repressor of JMJD3, Msx2-interacting nuclear target protein, to positively regulate infection-induced JMJD3 expression, FM generation and M2 phenotype. Investigations in in vivo murine models further substantiated these observations. Together, our study has attributed novel roles for JMJD3 and its regulators during mycobacterial infection that assist FM generation and fine-tune associated host immunity.

Foamy macrophages (FMs) not only provide a suitable survival niche for the mycobacteria in the granuloma but also are reservoirs for several inflammatory mediators that regulate mycobacterial pathogenesis. Hence, understanding the mechanisms that regulate infection-induced FM generation assumes importance. In this investigation, we present empirical evidence to support the role of host epigenetic mechanisms in generating FMs and thus facilitating mycobacterial persistence in vivo. We show that the signaling pathways that mediate mycobacteria-induced expression of JMJD3, a demethylase of the facultative repression mark, regulate the genes assisting in FM generation. Importantly, the identified pathway could largely contribute to the evasive responses during mycobacterial infection and suppression of such pathways during infection could confer stronger immunity. Together, these regulators could be potential candidates for host-directed therapies against mycobacterial infection.

Modulation of Host miRNAs by Intracellular Bacterial Pathogens

MicroRNAs (miRNAs) are short non-coding RNAs that regulate the expression of protein coding genes of viruses and eukaryotes at the post-transcriptional level. The eukaryotic genes regulated by miRNAs include those whose products are critical for biological processes such as cell proliferation, metabolic pathways, immune response, and development. It is now increasingly recognized that modulation of miRNAs associated with biological processes is one of the strategies adopted by bacterial pathogens to survive inside host cells. In this review, we present an overview of the recent findings on alterations of miRNAs in the host cells by facultative intracellular bacterial pathogens. In addition, we discuss how the altered miRNAs help in the survival of these pathogens in the intracellular environment.

Function and regulation of microRNA-31 in development and disease

MicroRNAs (miRNAs) are small noncoding RNAs that orchestrate numerous cellular processes both under normal physiological conditions as well as in diseases. This review summarizes the functional roles and transcriptional regulation of the highly evolutionarily conserved miRNA, microRNA-31 (miR-31). miR-31 is an important regulator of embryonic implantation, development, bone and muscle homeostasis, and immune system function. Its own regulation is disrupted during the onset and progression of cancer and autoimmune disorders such as psoriasis and systemic lupus erythematosus. Limited studies suggest that miR-31 is transcriptionally regulated by epigenetics, such as methylation and acetylation, as well as by a number of transcription factors. Overall, miR-31 regulates diverse cellular and developmental processes by targeting genes involved in cell proliferation, apoptosis, cell differentiation, and cell motility. Mol. Reprod. Dev. 83: 654-674, 2016 © 2016 Wiley Periodicals, Inc.

Effect of methacrylic acid beads on the sonic hedgehog signaling pathway and macrophage polarization in a subcutaneous injection mouse model

Poly(methacrylic acid-co-methyl methacrylate) (MAA) beads promote a vascular regenerative response when used in diabetic wound healing. Previous studies reported that MAA beads modulated the expression of sonic hedgehog (Shh) and inflammation related genes in diabetic wounds. The aim of this work was to follow up on these observations in a subcutaneous injection model to study the host response in the absence of the confounding factors of diabetic wound healing. In this model, MAA beads improved vascularization in healthy mice of both sexes compared to control poly(methyl methacrylate) (MM) beads, with a stronger effect seen in males than females. MAA-induced vessels were perfusable, as evidenced from the CLARITY-processed images. In Shh-Cre-eGFP/Ptch1-LacZ non-diabetic transgenic mice, the increased vessel formation was accompanied by a higher density of cells expressing GFP (Shh) and β-Gal (patched 1, Ptch1) suggesting MAA enhanced the activation of the Shh pathway. Ptch1 is the Shh receptor and a target of the pathway. MAA beads also modulated the inflammatory cell infiltrate in CD1 mice: more neutrophils and more macrophages were noted with MAA relative to MM beads at days 1 and 7, respectively. In addition, MAA beads biased macrophages towards a MHCII-CD206+ ("M2") polarization state. This study suggests that the Shh pathway and an altered inflammatory response are two elements of the complex mechanism whereby MAA-based biomaterials effect vascular regeneration.

Mycobacteria-responsive sonic hedgehog signaling mediates programmed death-ligand 1- and prostaglandin E2-induced regulatory T cell expansion

CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) are exploited by mycobacteria to subvert the protective host immune responses. The Treg expansion in the periphery requires signaling by professional antigen presenting cells and in particularly dendritic cells (DC). However, precise molecular mechanisms by which mycobacteria instruct Treg expansion via DCs are not established. Here we demonstrate that mycobacteria-responsive sonic hedgehog (SHH) signaling in human DCs leads to programmed death ligand-1 (PD-L1) expression and cyclooxygenase (COX)-2-catalyzed prostaglandin E2 (PGE2) that orchestrate mycobacterial infection-induced expansion of Tregs. While SHH-responsive transcription factor GLI1 directly arbitrated COX-2 transcription, specific microRNAs, miR-324-5p and miR-338-5p, which target PD-L1 were downregulated by SHH signaling. Further, counter-regulatory roles of SHH and NOTCH1 signaling during mycobacterial-infection of human DCs was also evident. Together, our results establish that Mycobacterium directs a fine-balance of host signaling pathways and molecular regulators in human DCs to expand Tregs that favour immune evasion of the pathogen.

Pathogens Use and Abuse MicroRNAs to Deceive the Immune System

Emerging evidence has demonstrated that microRNAs (miRs) play a role in the survival and amplification of viruses, bacteria and other pathogens. There are various ways in which pathogens can benefit from miR-directed alterations in protein translation and signal transduction. Members of the herpesviridae family have previously been shown to encode multiple miRs, while the production of miRs by viruses like HIV-1 remained controversial. Recently, novel techniques have facilitated the elucidation of true miR targets by establishing miR-argonaute association and the subsequent interactions with their cognate cellular mRNAs. This, in combination with miR reporter assays, has generated physiologically relevant evidence that miRs from the herpesviridae family have the potential to downregulate multiple cellular targets, which are involved in immune activation, cytokine signaling and apoptosis. In addition, viruses and bacteria have also been linked to the induction of host cellular miRs, which have the capacity to mitigate immune activation, cytokine signaling and apoptosis. Interfering with miR expression may be clinically relevant. In the case of hepatitis C infection, the cellular miR-122 is already targeted therapeutically. This not only exemplifies how important miRs can be for the survival of specific viruses, but it also delineates the potential to use miRs as drug targets. In this paper we will review the latest reports on viruses and bacteria that abuse miR regulation for their benefit, which may be of interest in the development of miR-directed therapies.

TNF-α-induced NF-κB activation upregulates microRNA-150-3p and inhibits osteogenesis of mesenchymal stem cells by targeting β-catenin

Although systemic or local inflammation, commonly featured by cytokine activation, is implicated in patients with bone loss, the underlying mechanisms are still elusive. As microRNAs (miR), a class of small non-coding RNAs involved in essential physiological processes, have been found in bone cells, we aimed to investigate the role of miR for modulating osteogenesis in inflammatory milieu using human bone marrow mesenchymal stem cells (hBM-MSCs). Induced by proinflammatory cytokine TNF-α, miR-150-3p was identified as a key player in suppressing osteogenic differentiation through downregulating β-catenin, a transcriptional co-activator promoting bone formation. TNF-α treatment increased the levels of miR-150-3p, which directly targeted the 3'-UTR of β-catenin mRNA and in turn repressed its expression. In addition, we observed that miR-150-3p expression was increased by TNF-α via IKK-dependent NF-κB signalling. There are three putative NF-κB binding sites in the promoter region of miR-150, and we identified -686 region as the major NF-κB binding site for stimulation of miR-150 expression by TNF-α. Finally, the osteogenic differentiation of hBM-MSCs was inhibited by either miR-150-3p overexpression or TNF-α treatment, which was prevented by anti-miR-150-3p oligonucleotides. Taken together, our data suggested that miR-150-3p integrated inflammation signalling and osteogenic differentiation and may contribute to the inhibition effects of inflammation on bone formation, thus expanding the pathophysiological functions of microRNAs in bone diseases.

MiR-150 Regulates Poststroke Cerebral Angiogenesis via Vascular Endothelial Growth Factor in Rats

AIMS

Angiogenesis is a harmonized target for poststroke recovery. Therefore, exploring the mechanisms involved in angiogenesis after stroke is vitally significant. In this study, we are reporting a miR-150-based mechanism underlying cerebral poststroke angiogenesis.

METHODS

Rat models of middle cerebral artery occlusion (MCAO) and cell models of oxygen-glucose deprivation were conducted. Capillary density, tube formation, cell proliferation, and cell migration were measured by FITC-dextran assay, matrigel assay, Ki-67 staining, and wound healing assay, respectively. The expression of miR-150 and vascular endothelial growth factor (VEGF) was, respectively, measured by RT-PCR and Western blotting. Dual-luciferase assay was conducted to confirm the binding sites between miR-150 and VEGF.

RESULTS

We found that miR-150 expression in the brain and serum of rats subjected to cerebral ischemia, and in oxygen-glucose-deprived brain microvascular endothelial cells (BMVECs) and astrocytes. Upregulation of miR-150 expression could decrease vascular density of infarct border zone in rat after MCAO and decrease tube formation, proliferation, and migration of BMVECs. We also found that miR-150 could negatively regulate the expression of VEGF, and VEGF was confirmed to be a direct target of miR-150. Moreover, VEGF mediated the function of miR-150 on tube formation, proliferation, and migration of BMVECs.

CONCLUSIONS

Our data suggested that miR-150 could regulate cerebral poststroke angiogenesis in rats through VEGF.

Epigenetics and miRNA during bacteria-induced host immune responses

Various cellular processes including the pathogen-specific immune responses, host-pathogen interactions and the related evasion mechanisms rely on the ability of the immune cells to be reprogrammed accurately and in many cases instantaneously. In this context, the exact functions of epigenetic and miRNA-mediated regulation of genes, coupled with recent advent in techniques that aid such studies, make it an attractive field for research. Here, we review examples that involve the epigenetic and miRNA control of the host immune system during infection with bacteria. Interestingly, many pathogens utilize the epigenetic and miRNA machinery to modify and evade the host immune responses. Thus, we believe that global epigenetic and miRNA mapping of such host-pathogen interactions would provide key insights into their cellular functions and help to identify various determinants for therapeutic value.

Ac2PIM-responsive miR-150 and miR-143 target receptor-interacting protein kinase 2 and transforming growth factor beta-activated kinase 1 to suppress NOD2-induced immunomodulators

Specific and coordinated regulation of innate immune receptor-driven signaling networks often determines the net outcome of the immune responses. Here, we investigated the cross-regulation of toll-like receptor (TLR)2 and nucleotide-binding oligomerization domain (NOD)2 pathways mediated by Ac2PIM, a tetra-acylated form of mycobacterial cell wall component and muramyl dipeptide (MDP), a peptidoglycan derivative respectively. While Ac2PIM treatment of macrophages compromised their ability to induce NOD2-dependent immunomodulators like cyclooxygenase (COX)-2, suppressor of cytokine signaling (SOCS)-3, and matrix metalloproteinase (MMP)-9, no change in the NOD2-responsive NO, TNF-α, VEGF-A, and IL-12 levels was observed. Further, genome-wide microRNA expression profiling identified Ac2PIM-responsive miR-150 and miR-143 to target NOD2 signaling adaptors, RIP2 and TAK1, respectively. Interestingly, Ac2PIM was found to activate the SRC-FAK-PYK2-CREB cascade via TLR2 to recruit CBP/P300 at the promoters of miR-150 and miR-143 and epigenetically induce their expression. Loss-of-function studies utilizing specific miRNA inhibitors establish that Ac2PIM, via the miRNAs, abrogate NOD2-induced PI3K-PKCδ-MAPK pathway to suppress β-catenin-mediated expression of COX-2, SOCS-3, and MMP-9. Our investigation has thus underscored the negative regulatory role of Ac2PIM-TLR2 signaling on NOD2 pathway which could broaden our understanding on vaccine potential or adjuvant utilities of Ac2PIM and/or MDP.

MiR-31 modulates coelomocytes ROS production via targeting p105 in Vibrio splendidus challenged sea cucumber Apostichopus japonicus in vitro and in vivo

MiR-31 is a critical regulator of gene expression in many pathogenic processes in vertebrates. In this study, we identified p105 as a novel target of miR-31 in Apostichopus japonicus and investigated their regulatory roles in vitro and in vivo. The negative expression profiles between miR-31 and Ajp105 were detected in both LPS-exposed primary coelomocytes and Vibrio splendidus-challenged sea cucumber. Co-infection miR-31 mimics significantly depressed the expression of Ajp105 and increased ROS production in vitro. In contrast, miR-31 inhibitor significantly elevated the expression of Ajp105 and decreased ROS level. Consistently, miR-31 over-expression or Ajp105 silencing in vivo both greatly promoted ROS accumulation. Taken together, our findings confirmed that miR-31 could modulate respiratory burst via targeting Ajp105 during sea cucumber pathological development.

Differential expression of microRNAs in Francisella tularensis-infected human macrophages: miR-155-dependent downregulation of MyD88 inhibits the inflammatory response

Francisella tularensis is a Gram-negative, facultative intracellular pathogen that replicates in the cytosol of macrophages and is the causative agent of the potentially fatal disease tularemia. A characteristic feature of F. tularensis is its limited proinflammatory capacity, but the mechanisms that underlie the diminished host response to this organism are only partially defined. Recently, microRNAs have emerged as important regulators of immunity and inflammation. In the present study we investigated the microRNA response of primary human monocyte-derived macrophages (MDMs) to F. tularensis and identified 10 microRNAs that were significantly differentially expressed after infection with the live vaccine strain (LVS), as judged by Taqman Low Density Array profiling. Among the microRNAs identified, miR-155 is of particular interest as its established direct targets include components of the Toll-like receptor (TLR) pathway, which is essential for innate defense and proinflammatory cytokine production. Additional studies demonstrated that miR-155 acted by translational repression to downregulate the TLR adapter protein MyD88 and the inositol 5′-phosphatase SHIP-1 in MDMs infected with F. tularensis LVS or the fully virulent strain Schu S4. Kinetic analyses indicated that miR-155 increased progressively 3-18 hours after infection with LVS or Schu S4, and target proteins disappeared after 12–18 hours. Dynamic modulation of MyD88 and SHIP-1 was confirmed using specific pre-miRs and anti-miRs to increase and decrease miR-155 levels, respectively. Of note, miR-155 did not contribute to the attenuated cytokine response triggered by F. tularensis phagocytosis. Instead, this microRNA was required for the ability of LVS-infected cells to inhibit endotoxin-stimulated TNFα secretion 18–24 hours after infection. Thus, our data are consistent with the ability of miR-155 to act as a global negative regulator of the inflammatory response in F. tularensis-infected human macrophages.

The WNT signaling pathway contributes to dectin-1-dependent inhibition of Toll-like receptor-induced inflammatory signature

Macrophages regulate cell fate decisions during microbial challenges by carefully titrating signaling events activated by innate receptors such as dectin-1 or Toll-like receptors (TLRs). Here, we demonstrate that dectin-1 activation robustly dampens TLR-induced proinflammatory signature in macrophages. Dectin-1 induced the stabilization of β-catenin via spleen tyrosine kinase (Syk)-reactive oxygen species (ROS) signals, contributing to the expression of WNT5A. Subsequently, WNT5A-responsive protein inhibitors of activated STAT (PIAS-1) and suppressor of cytokine signaling 1 (SOCS-1) mediate the downregulation of IRAK-1, IRAK-4, and MyD88, resulting in decreased expression of interleukin 12 (IL-12), IL-1β, and tumor necrosis factor alpha (TNF-α). In vivo activation of dectin-1 with pathogenic fungi or ligand resulted in an increased bacterial burden of Mycobacteria, Klebsiella, Staphylococcus, or Escherichia, with a concomitant decrease in TLR-triggered proinflammatory cytokines. All together, our study establishes a new role for dectin-1-responsive inhibitory mechanisms employed by virulent fungi to limit the proinflammatory environment of the host.

Mycobacterium bovis BCG promotes tumor cell survival from tumor necrosis factor-α-induced apoptosis

Background

Increased incidence of lung cancer among pulmonary tuberculosis patients suggests mycobacteria-induced tumorigenic response in the host. The alveolar epithelial cells, candidate cells that form lung adenocarcinoma, constitute a niche for mycobacterial replication and infection. We thus explored the possible mechanism of M. bovis Bacillus Calmette-Guérin (BCG)-assisted tumorigenicity in type II epithelial cells, human lung adenocarcinoma A549 and other cancer cells.

Methods

Cancer cell lines originating from lung, colon, bladder, liver, breast, skin and cervix were treated with tumor necrosis factor (TNF)-α in presence or absence of BCG infection. p53, COP1 and sonic hedgehog (SHH) signaling markers were determined by immunoblotting and luciferase assays, and quantitative real time PCR was done for p53-responsive pro-apoptotic genes and SHH signaling markers. MTT assays and Annexin V staining were utilized to study apoptosis. Gain- and loss-of-function approaches were used to investigate the role for SHH and COP1 signaling during apoptosis. A549 xenografted mice were used to validate the contribution of BCG during TNF-α treatment.

Results

Here, we show that BCG inhibits TNF-α-mediated apoptosis in A549 cells via downregulation of p53 expression. Substantiating this observation, BCG rescued A549 xenografts from TNF-α-mediated tumor clearance in nude mice. Furthermore, activation of SHH signaling by BCG induced the expression of an E3 ubiquitin ligase, COP1. SHH-driven COP1 targeted p53, thereby facilitating downregulation of p53-responsive pro-apoptotic genes and inhibition of apoptosis. Similar effects of BCG could be shown for HCT116, T24, MNT-1, HepG2 and HELA cells but not for HCT116 p53^-/- and MDA-MB-231 cells.

Conclusion

Our results not only highlight possible explanations for the coexistence of pulmonary tuberculosis and lung cancer but also address probable reasons for failure of BCG immunotherapy of cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-210) contains supplementary material, which is available to authorized users.