MicroRNAs in TGF-β/Smad-mediated Tissue Fibrosis

LncRNA-Dependent Mechanisms of Transforming Growth Factor-β: From Tissue Fibrosis to Cancer Progression

Transforming growth factor-β (TGF-β) is a crucial pathogenic mediator of inflammatory diseases. In tissue fibrosis, TGF-β regulates the pathogenic activity of infiltrated immunocytes and promotes extracellular matrix production via de novo myofibroblast generation and kidney cell activation. In cancer, TGF-β promotes cancer invasion and metastasis by enhancing the stemness and epithelial mesenchymal transition of cancer cells. However, TGF-β is highly pleiotropic in both tissue fibrosis and cancers, and thus, direct targeting of TGF-β may also block its protective anti-inflammatory and tumor-suppressive effects, resulting in undesirable outcomes. Increasing evidence suggests the involvement of long non-coding RNAs (lncRNAs) in TGF-β-driven tissue fibrosis and cancer progression with a high cell-type and disease specificity, serving as an ideal target for therapeutic development. In this review, the mechanism and translational potential of TGF-β-associated lncRNAs in tissue fibrosis and cancer will be discussed.

Astragaloside IV inhibits cardiac fibrosis via miR-135a-TRPM7-TGF-β/Smads pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cardiac fibrosis is a common characteristic of many cardiac diseases. Our previous results showed that TRPM7 channel played an important role in the fibrosis process. MicroRNA-135a was reported to get involved in the fibrotic process. Astragalus membranaceus (Fisch.) Bunge was widely used in Chinese traditional medicine and showed cardiac protective effects in previous researches. Astragaloside IV(ASG), which is regarded as the most important ingredient of Astragalus, has been showed the effect of cardiac protection via various mechanisms, while no data suggested its action related to miRNAs regulation.

AIM OF THE STUDY

The objective of this article is to investigate the inhibition effect of ASG on cardiac fibrosis through the miR-135a-TRPM7-TGF-β/Smads pathway.

MATERIALS AND METHODS

We extracted the active components from herb according to the paper and measured the content of ASG from the mixture via HPLC. The inhibition potency of cardiac hypertrophy between total extract of Astragalus and ASG was compared. SD rats were treated with ISO (5 mg/kg/day) subcutaneously (s.c.) for 14 days, ASG (10 mg/kg/d) and Astragalus extract (AE) (4.35 g/kg/d, which contained about ASG 10 mg) were given p.o. from the 6th day of the modeling. Cardiac fibroblasts (CFs) of neonatal rats were incubated with ISO (10 μM) and treated with ASG (10 μM) simultaneously for 24 h.

RESULTS

The results showed that both AE and ASG treatment reduced the TRPM7 expression from the gene level and inhibited cardiac fibrosis. ASG group showed similar potency as the AE mixture. ASG treatment significantly decreased the current, mRNA and protein expression of TRPM7 which was one of targets of miR-135a. The activation of TGF-β/Smads pathway was suppressed and the expression of α-SMA and Collagen I were also decreased obviously. In addition, our results showed that there was a positive feedback between the activation of TGF-β/Smads pathway and the elevation of TRPM7, both of which could promote the development of myocardial fibrosis.

CONCLUSIONS

AE had the effect of cardiac fibrosis inhibition and decreased the mRNA expression of TRPM7. ASG, as one of the effective ingredients of AE, showed the same potency when given the same dose. ASG inhibited cardiac fibrosis by targeting the miR-135a-TRPM7-TGF-β/Smads pathway.

Altered miRNA expression in pulmonary sarcoidosis

Background

miRNAs control important cellular functions including angiogenesis/angiostasis or fibrosis and reveal altered expression during pathological processes in the lung.

Methods

The aim of the study was to investigate the expression of selected miRNAs (miR-let7f, miR-15b, miR-16, miR-20a, miR-27b, miR-128a, miR-130a, miR-192 miR-221, miR-222) in patients with pulmonary sarcoidosis (n = 94) and controls (n = 50). The expression was assessed by q-PCR in BALF cells and peripheral blood lymphocytes (PB lymphocytes). For statistical analysis, the Kruskal–Wallis test, Mann–Whitney U- test, Neuman–Keuls’ multiple comparison test, and Spearman’s rank correlation were used.

Results

In BALF cells, significantly higher expression of miR-192 and miR-221 and lower expression of miR-15b were found in patients than controls. MiR-27b, miR-192 and miR-221 expression was significantly higher in patients without parenchymal involvement (stages I) than those at stages II-IV. Patients with acute disease demonstrated significantly higher miR-27b, miR-192 and miR-221 expression than those with insidious onset. For PB lymphocytes, patients demonstrated significantly greater miR-15b, miR-27b, miR-192, miR-221 and miR-222 expression, but lower miR-let7f and miR-130a expression, than controls. Stage I patients demonstrated significantly higher miR-16 and miR-15b expression than those in stages II-IV, and patients with the acute form demonstrated higher miR-130a and miR-15b expression. In BALF cells, miR-16 and miR-20a expression was significantly higher in patients with lung volume restriction, and miR-let7f was higher in the PB lymphocytes in patients with obturation. Several correlations were observed between the pattern of miRNA expression, lung function parameters and selected laboratory markers.

Conclusion

The obtained results suggest that the studied miRNAs play a role in the pathogenesis of sarcoidosis, and that some of them might have negative prognostic value.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-016-0266-6) contains supplementary material, which is available to authorized users.

Contribution of microRNA to pathological fibrosis in cardio-renal syndrome: impact of uremic toxins

Progressive reduction in kidney function in patients following myocardial infarction (MI) is associated with an increase in circulating uremic toxins levels leading to increased extracellular matrix deposition. We have recently reported that treatment with uremic toxin adsorbent AST-120 in rats with MI inhibits serum levels of uremic toxin indoxyl sulfate (IS) and downregulates expression of cardiac profibrotic cytokine transforming growth factor beta (TGF-β1). In this study, we examined the effect of uremic toxins post-MI on cardiac microRNA-21 and microRNA-29b expression, and also the regulation of target genes and matrix remodeling proteins involved in TGFβ1 and angiotensin II signaling pathways. Sixteen weeks after MI, cardiac tissues were assessed for pathological and molecular changes. The percentage area of cardiac fibrosis was 4.67 ± 0.17 in vehicle-treated MI, 2.9 ± 0.26 in sham, and 3.32 ± 0.38 in AST-120-treated MI, group of rats. Compared to sham group, we found a twofold increase in the cardiac expression of microRNA-21 and 0.5-fold decrease in microRNA-29b in heart tissue from vehicle-treated MI. Treatment with AST-120 lowered serum IS levels and attenuated both, cardiac fibrosis and changes in expression of these microRNAs observed after MI. We also found increased mRNA expression of angiotensin-converting enzyme (ACE) and angiotensin receptor 1a (Agtr1a) in cardiac tissue collected from MI rats. Treatment with AST-120 attenuated both, expression of ACE and Agtr1a mRNA. Exposure of rat cardiac fibroblasts to IS upregulated angiotensin II signaling and altered the expression of both microRNA-21 and microRNA-29b. These results collectively suggest a clear role of IS in altering microRNA-21 and microRNA-29b in MI heart, via a mechanism involving angiotensin signaling pathway, which leads to cardiac fibrosis.