Role of miRNAs in T-cell activation and Th17/Treg-cell imbalance in acquired aplastic anemia

BACKGROUND

Altered T-cell repertoire with an aberrant T-cell activation and imbalance of the Th17/Treg cells has been reported in acquired aplastic anemia (aAA). miRNAs are well known to orchestrate T-cell activation and differentiation, however, their role in aAA is poorly characterized. The study aimed at identifying the profile of miRNAs likely to be involved in T-cell activation and the Th17/Treg-cell imbalance in aAA, to explore newer therapeutic targets.

METHODS

Five milliliters peripheral blood samples from 30 patients of aAA and 15 healthy controls were subjected to flow cytometry for evaluating Th17- and Treg-cell subsets. The differential expression of 7 selected miRNAs viz; hsa-miR-126-3p, miR-146b-5p, miR-155-5p, miR-16, miR-17, miR-326, and miR-181c was evaluated in the PB-MNCs. Expression analysis of the miRNAs was performed using qRT-PCR and fold change was calculated by 2-ΔΔCt method. The alterations in the target genes of deregulated miRNAs were assessed by qRT-PCR. The targets studied included various transcription factors, cytokines, and downstream proteins.

RESULTS

The absolute CD3+ lymphocytes were significantly elevated in the PB of aAA patients when compared with healthy controls (p < 0.0035), however, the CD4:CD8 ratio was unperturbed. Th17: Treg-cell ratio was altered in aAA patients (9.1 vs. 3.7%, p value <0.05), which correlated positively with disease severity and the PNH positive aAA. Across all severities of aAA, altered expression of the 07 miRNAs was noted in comparison to controls; upregulation of miR-155 (FC-2.174, p-value-0.0001), miR-146 (FC-2.006, p-value-0.0001), and miR-17 (FC-3.1, p-value-0.0001), and downregulation of miR-126 (FC-0.329, p-value-0.0001), miR-181c (FC-0.317, p-value-0.0001), miR-16 (FC-0.348, p-value-0.0001), and miR-326 (FC-0.334, p-value-0.0001). Target study for these miRNAs revealed an increased expression of transcription factors responsible for Th1 and Th17 differentiation (T-bet, RORϒt, IL-17, IL-6, and IFN-ϒ), T-cell activation (NFκB, MYC, and PIK3R2), downregulation of FOX-P3, and other regulatory downstream molecules like SHIP-1, ETS-1, IRAK-1, TRAF-6, and PTEN.

CONCLUSION

The study for the first time highlights the plausible role of different miRNAs in deregulating the Th17/Treg-cell imbalance in aAA, and comprehensively suggest the role of altered NF-kB and mTOR pathways in aAA. The axis may be actively explored for development of newer therapeutic targets in aAA.

Bone marrow plasma metabonomics of idiopathic acquired aplastic anemia patients using 1H nuclear magnetic resonance spectroscopy

INTRODUCTION

Idiopathic acquired aplastic anemia (AA) is a bone marrow failure disorder where aberrant T-cell functions lead to depletion of hematopoietic stem and progenitor cells in the bone marrow (BM) microenvironment. T-cells undergo metabolic rewiring, which regulates their proliferation and differentiation. Therefore, studying metabolic variation in AA patients may aid us with a better understanding of the T-cell regulatory pathways governed by metabolites and their pathological engagement in the disease.

OBJECTIVE

To identify the differential metabolites in BM plasma of AA patients, AA follow-up (AAF) in comparison to normal controls (NC) and to identify potential disease biomarker(s).

METHODS

The study used 1D 1H NMR Carr-Purcell-Meiboom-Gill (CPMG) spectra to identify the metabolites present in the BM plasma samples of AA (n = 40), AAF (n = 16), and NC (n = 20). Metabolic differences between the groups and predictive biomarkers were identified by using multivariate analysis and receiver operating characteristic (ROC) module of Metaboanalyst V5.0 tool, respectively.

RESULTS

The AA and AAF samples were well discriminated from NC group as per Principal Component analysis (PCA). Further, we found significant alteration in the levels of 17 metabolites in AA involved in amino-acid (Leucine, serine, threonine, phenylalanine, lysine, histidine, valine, tyrosine, and proline), carbohydrate (Glucose, lactate and mannose), fatty acid (Acetate, glycerol myo-inositol and citrate), and purine metabolism (hypoxanthine) in comparison to NC. Additionally, biomarker analysis predicted Hypoxanthine and Acetate can be used as a potential biomarker.

CONCLUSION

The study highlights the significant metabolic alterations in the BM plasma of AA patients which may have implication in the disease pathobiology.

Targeting Extracellular RNA Mitigates Hepatic Lipotoxicity and Liver Injury in NASH

Non-alcoholic steatohepatitis (NASH) is a clinically serious stage of non-alcoholic fatty liver disease (NAFLD). Histologically characterized by hepatocyte ballooning, immune cell infiltration, and fibrosis, NASH, at a molecular level, involves lipid-induced hepatocyte death and cytokine production. Currently, there are very few diagnostic biomarkers available to screen for NASH, and no pharmacological intervention is available for its treatment. In this study, we show that hepatocyte damage induced by lipotoxicity results in the release of extracellular RNAs (eRNAs), which serve as damage-associated molecular patterns (DAMPs) that stimulate the expression of pro-apoptotic and pro-inflammatory cytokines, aggravate inflammation, and lead to cell death in HepG2 cells. Furthermore, the inhibition of eRNA activity by RNase 1 significantly increases cellular viability and reduces NF-kB-mediated cytokine production. Similarly, RNase 1 administration significantly improves hepatic steatosis, inflammatory and injury markers in a murine NASH model. Therefore, this study, for the first time, underscores the therapeutic potential of inhibiting eRNA action as a novel strategy for NASH treatment.

ULK1 inhibition attenuates telomerase activity in hepatic cells

Autophagy and telomere maintenance are two cellular survival processes that show a strong correlation during human ageing and cancer growth, however, their causal relationship remains unclear. In this study, using an unbiased transcriptomics approach, we uncover a novel role of autophagy genes in regulating telomere extension and maintenance pathways. Concomitantly, the pharmacological inhibition of ULK1 (Unc-51 like autophagy activating kinase 1) attenuated human telomerase reverse transcriptase (hTERT) gene expression and telomerase activity in HepG2 cells. Furthermore, the suppression of telomerase activity upon ULK1 inhibition was associated with telomere shortening and onset of cellular senescence in HepG2 cells. These results, thus, demonstrate a direct role of autophagy in maintaining cellular longevity via regulation of telomerase activity, which may have implications in the pathophysiology of ageing and cancers.

Extracellular vesicles from bone marrow mesenchymal stromal cells of severe aplastic anemia patients attenuate hematopoietic functions of CD34+ hematopoietic stem and progenitor cells

Mesenchymal stromal cells (MSC) regulate hematopoiesis in the bone marrow (BM) niche and extracellular vesicles (EVs) released by BM-MSC are important mediators of the cross-talk between BM-MSC and hematopoietic stem and progenitor cells (HSPC). We have previously demonstrated that BM-MSC of severe aplastic anemia (SAA) patients have an altered expression of hematopoiesis regulatory molecules. In the present study, we observed that CD34⁺ HSPC when cocultured with BM-MSC EVs from aplastic anemia patients exhibited a significant reduction in colony-forming units (p = .001), cell proliferation (p = .002), and increased apoptosis (p > .001) when compared to coculture with BM-MSC EVs from controls. Collectively, our results highlight that EVs derived from the BM-MSC of SAA patients impair the hematopoiesis supporting function of HSPC.

A New and Highly Sensitive Serum Mannoprotein Lateral Flow Assay for Point-of-Care Diagnosis of Invasive Aspergillosis (Tripathy Method)

Background and objectives

The mannoprotein lateral flow assay (MP-LFA) or Aspergillus-specific lateral flow device (AspLFD) is a novel rapid test for point-of-care diagnosis (PoC) of invasive aspergillosis (IA), but its routine clinical application is hampered due to low sensitivity (S_n) of the assay in serum. Therefore, this study aimed to develop a new method to enhance the S_n of the serum MP-LFA.

Methodology

In the new method (Tripathy method), we used direct heating of the serum without any dilution at 120^°C for 15 minutes to purify the mannoprotein (MP) antigen of the Aspergillus. The MP-enriched serum supernatant obtained after centrifugation was loaded in an LFD cassette, and the results were read after 20 minutes using a digital cube reader. In parallel to our new method, AspLFD was performed according to the manufacturer’s instructions. The diagnostic performance of the two methods was evaluated using paired sera of true IA patients (IA, n=18) and healthy subjects (controls, n=20). The positivity of the two methods was also evaluated in the sera of leukemia patients with possible/probable IA (possible/probable IA; n=23).

Results

The Tripathy method had a significantly higher sensitivity (88.9% versus 55.5%; p<0.05) and diagnostic odds ratio (72.0 versus 23.7) than the standard AspLFD method. In receiver operating characteristic curve analysis for differentiation between IA patients and controls, although the Tripathy method (area under curve; AUC: 0.894, p<0.001) and AspLFD method (AUC: 0.753, p<0.001) were significantly associated with IA, the AUC of the Tripathy method was significantly higher than that of the AspLFD method (0.894 versus 0.753; p<0.05). In the sera of possible/probable IA, MP-LFA by the Tripathy method had a significantly higher rate of positivity than the AspLFD method (39.0% versus 21.7%; p<0.05).

Conclusion

Our data show that the Tripathy method is a highly sensitive method of MP-LFA for the PoC diagnosis of IA in clinical settings.

Ezetimibe attenuates experimental diabetes and renal pathologies via targeting the advanced glycation, oxidative stress and AGE-RAGE signalling in rats

The current in-vivo study was premeditated to uncover the protective role of ezetimibe (EZ) against advanced glycation endproducts (AGEs)-related pathologies in experimental diabetes. Our results showed that EZ markedly improved the altered biochemical markers of diabetes mellitus (DM) (FBG, HbA1c, insulin, microalbumin, and creatinine) and cardiovascular disease (in-vivo lipid/lipoprotein level and hepatic HMG-CoA reductase activity) along with diminished plasma carboxymethyl-lysine (CML) and renal fluorescent AGEs level. Gene expression study revealed that EZ significantly down-regulated the renal AGEs-receptor (RAGE), nuclear factor-κB (NFκB-2), transforming growth factor-β (TGF-β1), and matrix metalloproteinase-2 (MMP-2) mRNA expression, however, the neuropilin-1 (NRP-1) mRNA expression was up-regulated. In addition, EZ also maintained the redox status via decreasing the lipid peroxidation and protein-bound carbonyl content (CC) and increasing the activity of high-density lipoprotein (HDL)-associated-paraoxonase-1 (PON-1) and renal antioxidant enzymes as well as also protected renal histopathological features. We conclude that EZ exhibits antidiabetic and reno-protective properties in diabetic rats.

Differential expression of miRNAs and their target genes: Exploring a new perspective of acquired aplastic anemia pathogenesis

INTRODUCTION

MicroRNAs (miRNAs) play a critical role in orchestrating T cell differentiation and activation and may thus play a vital role in acquired aplastic anemia (aAA). The study aimed to evaluate the differential expression of selected miRNAs and their relevant target genes in bone marrow samples of aAA patients.

METHODS

Differential expression of 8 miRNAs viz; hsa-miR-126-3p, miR-145-5p, miR-155-5p, miR-150-5p, miR-146b-5p, miR-34a, miR-29a, and miR-29b was evaluated in the bone marrow mononuclear cells of aAA patients. TaqMan microRNA assay was performed for preparing the cDNA of specific miRNA, followed by expression analysis using qRT-PCR. Data were normalized using two endogenous controls, RNU6B and RNU48. Delta-delta CT method was used to calculate the fold change (FC) of miRNA expression in individual samples, and a FC of >1.5 was taken as significant. Target genes of these miRNAs were evaluated by qRT-PCR.

RESULTS

Thirty five samples of aAA patients and 20 controls were evaluated. Irrespective of the disease severity, five miRNAs were found to be deregulated; miR-126 (FC-0.348; P-value-.0001) and miR-145 (FC-0.31; P-value-.0001) were downregulated, while miR-155 (FC-3.50; P-value-.0067), miR-146 (FC-3.13; P-value-.0105), and miR-150 (FC-5.78; P-value-.0001) were upregulated. Target gene study revealed an upregulation of PIK3R2, MYC, SOCS1, and TRAF-6, and downregulation of MYB.

CONCLUSION

This is the first study from the Indian subcontinent demonstrating the presence of altered miRNA expression in the bone marrow samples of aAA patients, suggesting their role in the pathogenesis of the disease. A comprehensive study focusing on the effect of these miRNA-mRNA interactions is likely to open new avenues of management.

Mechanisms involved in epigenetic down-regulation of Gfap under maternal hypothyroidism

Thyroid hormones (TH) of maternal origin are crucial regulator of mammalian brain development during embryonic period. Although maternal TH deficiency during the critical periods of embryonic neo-cortical development often results in irreversible clinical outcomes, the fundamental basis of these abnormalities at a molecular level is still obscure. One of the key developmental process affected by maternal TH insufficiency is the delay in astrocyte maturation. Glial fibrillary acidic protein (Gfap) is a predominant cell marker of mature astrocyte and is regulated by TH status. Inspite, of being a TH responsive gene during neocortical development the mechanistic basis of Gfap transcriptional regulation by TH has remained elusive. In this study using rat model of maternal hypothyroidism, we provide evidence for an epigenetic silencing of Gfap under TH insufficiency and its recovery upon TH supplementation. Our results demonstrate increased DNA methylation coupled with decreased histone acetylation at the Gfap promoter leading to suppression of Gfap expression under maternal hypothyroidism. In concordance, we also observed a significant increase in histone deacetylase (HDAC) activity in neocortex of TH deficient embryos. Collectively, these results provide novel insight into the role of TH regulated epigenetic mechanisms, including DNA methylation, and histone modifications, which are critically important in mediating precise temporal neural gene regulation.

Development of a hybrid delta-endotoxin and its expression in tobacco and cotton for control of a polyphagous pest Spodoptera litura

A hybrid delta-endotoxin protein was designed against a polyphagous lepidopteran insect pest Spodoptera litura, which is tolerant to most of the known delta-endotoxins. The hybrid delta-endotoxin was created by replacing amino acid residues 530-587 in a poorly active natural Cry1Ea protein, with a highly homologous 70 amino acid region of Cry1Ca in domain III. The truncated delta-endotoxins Cry1Ea, Cry1Ca and the hybrid protein Cry1EC accumulated in Escherichia coli to form inclusion bodies. The solubilised Cry1EC made from E. coli was 4- fold more toxic to the larvae of S. litura than Cry1Ca, the best known delta-endotoxin against Spodoptera sp. None of the two truncated toxins, solubilised from E. coli caused larval mortality. However, trypsinised Cry1Ca protoxin obtained from E. coli and solubilised from inclusion bodies caused mortality of S. litura with LC50 513 ng/ml semi synthetic diet. A synthetic gene coding for the hybrid delta-endotoxin Cry1EC was designed for high level expression in plants, taking into consideration several features found in the highly expressed plant genes. Transgenic, single copy plants of tobacco as well as cotton were developed. The selected lines expressed Cry1EC at 0.1-0.7% of soluble leaf protein. Such plants were completely resistant to S. litura and caused 100% mortality in all stages of larval development. Hence, unlike in E. coli, the hybrid delta-endotoxin folded into a functionally active conformation in both tobacco and cotton leaves. The truncated Cry1EC expressed in tobacco leaves was about 8-fold more toxic (LC50 58 ng/ml diet) compared to expression in E. coli.