Valsartan ameliorates high glucose-induced peritoneal fibrosis by blocking mTORC1 signaling

Mmu_circ_0005373 and hsa_circ_0136255 participate in the pulmonary fibrosis of systemic sclerosis

The pathogenesis of SSc pulmonary fibrosis is complex and prognosis is poor. In order to find biomarkers to provide assistance in the diagnosis and treatment of systemic sclerosis (SSc), this study explored the role of SSc-related differentially expressed circRNAs in the fibrosis process. This study explored whether circular RNA (circRNA) mediated the mTOR signaling pathway by interacting with the eukaryotic translation initiation factor eIF4E-binding protein 1 (4E-BP1), participated in a competing endogenous RNA (ceRNA) network, and regulated the mechanism of pulmonary fibrosis in systemic sclerosis (SSc). The results showed that the expression of mmu_circ_0005373 was reduced, and mmu_circ_0005373 may regulate the mTOR signaling pathway by inhibiting the interacting with 4E-BP1 protein in the lung of SSc mice, and promote fibrosis in SSc. Hsa_circ_0136255, which is homologous to mmu_circ_0005373, is also reduced in SSc peripheral blood mononuclear cells, and predicted to interact with 4E-BP1 protein. Hsa_circ_0136255/hsa-miR-330-3p/TNFAIP3 ceRNA network had biological significance in SSc, and correlated with clinical data, including high-resolution CT, average expiratory flow at 25% vital capacity, neutrophil count, lymphocyte percentage, standard deviation of red blood cell distribution width, coefficient of variation of red blood cell distribution width, platelet distribution width, glutamic transaminase, γ-glutamyl transpeptidase, lymphocyte percentage, basophils percentage, red blood cell, plateletcrit, cholinesterase, and mean corpuscular hemoglobin concentration. Hsa_circ_0136255, hsa-miR-330-3p, and TNFAIP3 may be used as biomarkers for clinical diagnosis and treatment of SSc.

Inhibition of the rapamycin-insensitive mTORC1 /4E-BP1 axis attenuates TGF-β1-induced fibrotic response in human Tenon's fibroblasts

Subconjunctival fibrosis is the major cause of failure in both conventional and modern minimally invasive glaucoma surgeries (MIGSs) with subconjunctival filtration. The search for safe and effective anti-fibrotic agents is critical for improving long-term surgical outcomes. In this study, we investigated the effect of inhibiting the rapamycin-insensitive mTORC1/4E-BP1 axis on the transforming growth factor-beta 1(TGF-β1)-induced fibrotic responses in human Tenon's fibroblasts (HTFs), as well as in a rat model of glaucoma filtration surgery (GFS). Primary cultured HTFs were treated with 3 ng/mL TGF-β1 for 24 h, followed by treatment with 10 μM CZ415 for additional 24 h. Rapamycin (10 μM) was utilized as a control for mTORC1/4E-BP1 signaling insensitivity. The expression levels of fibrosis-associated molecules were measured using quantitative real-time PCR, Western blotting, and immunofluorescence analysis. Cell migration was assessed through the scratch wound assay. Additionally, a rat model of GFS was employed to evaluate the anti-fibrotic effect of CZ415 in vivo. Our findings indicated that both rapamycin and CZ415 treatment significantly reduced the TGF-β1-induced cell proliferation, migration, and the expression of pro-fibrotic factors in HTFs. CZ415 also more effectively inhibited TGF-β1-mediated collagen synthesis in HTFs compared to rapamycin. Activation of mTORC1/4E-BP signaling following TGF-β1 exposure was highly suppressed by CZ415 but was only modestly inhibited by rapamycin. Furthermore, CZ415 was found to decrease subconjunctival collagen deposition in rats post GFS. Our results suggest that rapamycin-insensitive mTORC1/4E-BP1 signaling plays a critical role in TGF-β1-driven collagen synthesis in HTFs. This study demonstrated that inhibition of the mTORC1/4E-BP1 axis offers superior anti-fibrotic efficacy compared to rapamycin and represents a promising target for improving the success rate of both traditional and modern GFSs.

Integrative analysis of chromatin accessibility and transcriptome landscapes in the induction of peritoneal fibrosis by high glucose

BACKGROUND

Peritoneal fibrosis is the prevailing complication induced by prolonged exposure to high glucose in patients undergoing peritoneal dialysis.

METHODS

To elucidate the molecular mechanisms underlying this process, we conducted an integrated analysis of the transcriptome and chromatin accessibility profiles of human peritoneal mesothelial cells (HMrSV5) during high-glucose treatment.

RESULTS

Our study identified 2775 differentially expressed genes (DEGs) related to high glucose-triggered pathological changes, including 1164 upregulated and 1611 downregulated genes. Genome-wide DEGs and network analysis revealed enrichment in the epithelial-mesenchymal transition (EMT), inflammatory response, hypoxia, and TGF-beta pathways. The enriched genes included VEGFA, HIF-1α, TGF-β1, EGF, TWIST2, and SNAI2. Using ATAC-seq, we identified 942 hyper (higher ATAC-seq signal in high glucose-treated HMrSV5 cells than in control cells) and 714 hypo (lower ATAC-seq signal in high glucose-treated HMrSV5 cells versus control cells) peaks with differential accessibility in high glucose-treated HMrSV5 cells versus controls. These differentially accessible regions were positively correlated (R = 0.934) with the nearest DEGs. These genes were associated with 566 up- and 398 downregulated genes, including SNAI2, TGF-β1, HIF-1α, FGF2, VEGFA, and VEGFC, which are involved in critical pathways identified by transcriptome analysis. Integrated ATAC-seq and RNA-seq analysis also revealed key transcription factors (TFs), such as HIF-1α, ARNTL, ELF1, SMAD3 and XBP1. Importantly, we demonstrated that HIF-1α is involved in the regulation of several key genes associated with EMT and the TGF-beta pathway. Notably, we predicted and experimentally validated that HIF-1α can exacerbate the expression of TGF-β1 in a high glucose-dependent manner, revealing a novel role of HIF-1α in high glucose-induced pathological changes in human peritoneal mesothelial cells (HPMCs).

CONCLUSIONS

In summary, our study provides a comprehensive view of the role of transcriptome deregulation and chromosome accessibility alterations in high glucose-induced pathological fibrotic changes in HPMCs. This analysis identified hub genes, signaling pathways, and key transcription factors involved in peritoneal fibrosis and highlighted the novel glucose-dependent regulation of TGF-β1 by HIF-1α. This integrated approach has offered a deeper understanding of the pathogenesis of peritoneal fibrosis and has indicated potential therapeutic targets for intervention.

High glucose dialysate-induced peritoneal fibrosis: Pathophysiology, underlying mechanisms and potential therapeutic strategies

Peritoneal dialysis is an efficient renal replacement therapy for patients with end-stage kidney disease. However, continuous exposure of the peritoneal membrane to dialysate frequently leads to peritoneal fibrosis, which alters the function of the peritoneal membrane and results in withdrawal from peritoneal dialysis in patients. Among others, high glucose dialysate is considered as a predisposing factor for peritoneal fibrosis in patients on peritoneal dialysis. Glucose-induced inflammation, metabolism disturbance, activation of the renin-angiotensin-aldosterone system, angiogenesis and noninflammation-induced reactive oxygen species are implicated in the pathogenesis of high glucose dialysate-induced peritoneal fibrosis. Specifically, high glucose causes chronic inflammation and recurrent peritonitis, which could cause migration and polarization of inflammatory cells, as well as release of cytokines and fibrosis. High glucose also interferes with lipid metabolism and glycolysis by activating the sterol-regulatory element-binding protein-2/cleavage-activating protein pathway and increasing hypoxia inducible factor-1α expression, leading to angiogenesis and peritoneal fibrosis. Activation of the renin-angiotensin-aldosterone system and Ras-mitogen activated protein kinase signaling pathway is another contributing factor in high glucose dialysate-induced fibrosis. Ultimately, activation of the transforming growth factor-β1/Smad pathway is involved in mesothelial-mesenchymal transition or epithelial-mesenchymal transition, which leads to the development of fibrosis. Although possible intervention strategies for peritoneal dialysate-induced fibrosis by targeting the transforming growth factor-β1/Smad pathway have occasionally been proposed, lack of laboratory evidence renders clinical decision-making difficult. We therefore aim to revisit the upstream pathways of transforming growth factor-beta1/Smad and propose potential therapeutic targets for high glucose-induced peritoneal fibrosis.

Backstage players of fibrosis: NOX4, mTOR, HDAC, and S1P; companions of TGF-β

The fibrotic process could be easily defined as a pathological excess of extracellular matrix deposition, leading to disruption of tissue architecture and eventually loss of function; however, this process involves a complex network of several signal transduction pathways. Virtually almost all organs could be affected by fibrosis, the most affected are the liver, lung, skin, kidney, heart, and eyes; in all of them, the transforming growth factor-beta (TGF-β) has a central role. The canonical and non-canonical signal pathways of TGF-β impact the fibrotic process at the cellular and molecular levels, inducing the epithelial-mesenchymal transition (EMT) and the induction of profibrotic gene expression with the consequent increase in proteins such as alpha-smooth actin (α-SMA), fibronectin, collagen, and other extracellular matrix proteins. Recently, it has been reported that some molecules that have not been typically associated with the fibrotic process, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), mammalian target of rapamycin (mTOR), histone deacetylases (HDAC), and sphingosine-1 phosphate (S1P); are critical in its development. In this review, we describe and discuss the role of these new players of fibrosis and the convergence with TGF-β signaling pathways, unveiling new insights into the panorama of fibrosis that could be useful for future therapeutic targets.

Aspirin restores endothelial function by mitigating 17β-estradiol-induced α-SMA accumulation and autophagy inhibition via Vps15 scaffold regulation of Beclin-1 phosphorylation

AIMS

Previous studies have shown that the widespread use of estrogen preparations can cause adverse outcomes such as thrombosis and cardiovascular disease. Autophagy is a biochemical process necessary to maintain cell homeostasis. The present study investigated whether E-2 mediates autophagy-induced endothelial cell dysfunction. The role of aspirin in this process was then studied.

MAIN METHODS

Western blot, fluorescence microscopy, electron transmission microscopy, plasma construction and transfection, vasoreactivity study in wire myograph are all used in this study.

KEY FINDINGS

We found that E-2 activated the PI3K/mTOR signaling pathway and inhibited the formation of the Atg14L-Beclin1-Vps34-Vps15 complex, thereby inhibiting autophagy. Aspirin promoted Beclin1 phosphorylation in autophagy initiation complexes and enhanced autophagy. Furthermore, E-2 treatment of HAECs resulted in endothelial dysfunction by inhibiting autophagy and leading to accumulation of α-smooth muscle actin (α-SMA). E-2 inhibited the activation of eNOS and reduced the expression of eNOS protein. In the mouse aortic vascular function test, E-2 disrupted endothelium-dependent vasodilation. An α-SMA-shRNA lentivirus eliminated the disruption to endothelium-dependent vasodilation by E-2. Aspirin inhibited α-SMA accumulation by enhancing autophagy, reversed endothelial functional impairment caused by E-2, and promoted endothelium-dependent vasodilation.

SIGNIFICANCE

This study provides new evidence that E-2 inhibits autophagy and induces abnormal accumulation of α-SMA, resulting in endothelial cell dysfunction and affecting vasodilation. Aspirin can effectively restore the endothelial cell function disrupted E-2.