Beraprost sodium mitigates renal interstitial fibrosis through repairing renal microvessels

A meta-analysis examining the impact of prostaglandins on diabetic nephropathy

BACKGROUND

In 2021, approximately 537 million adults globally had diabetes, with projections estimating an increase to 643 million by 2030 and 783 million by 2045. Uncontrolled diabetes can cause severe complications, including diabetic nephropathy, a prevalent microvascular disease and a primary contributor to end-stage renal failure, with an increasing mortality rate.

METHODS

Conduct a search for randomized controlled trials (RCTs) on the use of prostaglandins in treating diabetic nephropathy across PubMed, Cochrane Library, Web of Science, CNKI, and Wanfang databases. Two researchers will independently screen the retrieved literature, assess the methodological quality using the bias risk assessment tool from the Cochrane 5.1 manual, and conduct statistical data analysis.

RESULTS

A total of 1019 patients were included in 11 studies. The meta-analysis results show the effective rate of the test group, which was significantly higher (P < 0.01, OR 1.32; 95% CI 1.13-1.55) than the control group.24-h urinary protein quantification of the test group was lower (P < 0.01, SMD  - 2.12; 95% CI  - 3.26 to  - 0.99). The test group exhibited significantly lower levels of blood creatinine (P < 0.01, SMD  - 0.99; 95% CI  - 1.42 to  - 0.57) and blood urea nitrogen (P < 0.01, SMD  - 0.93; 95% CI  - 1.34 to  - 0.51).

CONCLUSION

The findings suggest that prostaglandins enhance the effective rate and improve 24-h urinary protein quantification, blood creatinine, and blood urea nitrogen levels in diabetic nephropathy patients.

LncRNA TUG1 mitigates chronic kidney disease through miR-542-3p/HIF-1α/VEGF axis

Renal interstitial fibrosis (RIF) is a common pathway in chronic kidney disease (CKD) that ultimately leads to end-stage renal failure, worsening both glomerulosclerosis and interstitial fibrosis. Ten percent of the adult population in the world suffers from CKD, and as the ageing population continues to rise, it is increasingly regarded as a global threat-a silent epidemic. CKD has been discovered to be closely associated with both long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), while the precise molecular processes behind this relationship are still unclear. This study evaluated the impact of miR-542-3p and lncRNA TUG1 on renal fibrosis, along with the underlying regulatory mechanisms. Through in vitro tube formation assays, research demonstrated that knocking down lncRNA TUG1 may enhance angiogenesis and repair damaged endothelial cell-cell connections. We used Western blot and qRT-PCR methods in the unilateral ureteral obstruction (UUO) model to identify tissue hypoxia and fibrotic lesions. Additionally, a cutting-edge method known as fluorescence microangiography (FMA) was employed to detect damage to the peritubular capillaries (PTCs), with MATLAB software utilised for data evaluation. Furthermore, the coexpression of CD31 and α-SMA helped identify cells in the obstructed kidney that were transitioning from endothelium to myofibroblasts. On the contrary, lncRNA TUG1 downregulation showed a protective effect against the transition from endothelial cells to myofibroblasts. Additionally, knocking down lncRNA TUG1 has been shown to reduce the expression of fibrotic markers by alleviating tissue hypoxia. This effect was significantly counteracted by the inhibition of miR-542-3p. Collectively, our findings offer fresh perspectives on how lncRNA TUG1 and the miR-542-3p/HIF-1α/VEGF axis are regulated as renal fibrosis advances.

Clinical efficacy of beraprost sodium in treating chronic kidney disease: A six-month prospective study

Objective

To investigate the clinical efficacy of beraprost sodium (BPS) in the treatment of chronic kidney disease (CKD).

Methods

In this single-centre, prospective, controlled, single-blind study, 252 patients diagnosed with CKD and treated at the Affiliated Hospital of Xuzhou Medical University were enrolled from September 2018 to June 2021. All participants were randomised into three groups: the control, BPS 40 μg, and BPS 20 μg groups. Both treatment groups were administered conventional therapy for 6 months. Renal function in the three groups was measured and compared 3 and 6 months post-treatment.

Results

1. Renal function in the BPS 20 μg and BPS 40 μg groups was better than that in the control group after 3 and 6 months of treatment. 2. After 3 months of treatment, the levels of serum creatinine (P = 0.043), cystatin C (P = 0.039), and 24 h urinary total protein (P = 0.041) in the BPS 40 μg group were significantly lower than those in the BPS 20 μg group, the eGFR (P = 0.046) level was higher than that in the BPS 20 μg group, and the index improvement rate was better than that in the BPS 20 μg group (P < 0.05). 3. After 6 months of treatment, the improvement in renal function in the BPS 20 μg group was close to that in the BPS 40 μg group (P > 0.05).

Conclusion

BPS improved renal function, reduced urinary protein levels, and delayed CKD progression. The clinical efficacy of BPS in the 40 μg group was faster than that in the BPS 20 μg group. The long-term use of BPS is effective in patients with CKD.

Clinical efficacy and safety of beraprost sodium in the treatment of nephrotic syndrome: A meta-analysis

BACKGROUND

Beraprost sodium has been shown to have positive effects in the kidney; however, its efficacy and safety in the treatment of nephrotic syndrome (NS) are currently unknown. Therefore, the aim of this meta-analysis was to evaluate the clinical efficacy and safety of beraprost sodium in the treatment of NS.

METHODS

We systematically searched EMBASE, PubMed, MEDLINE, China National Knowledge Internet (CNKI), Chinese Biomedical Database (CBM), and Wanfang database for articles from their inception to August 2022.

RESULTS

A total of 12 randomized controlled trials (RCTs) involving 1200 subjects were collected for careful evaluation. The meta-analysis indicated that compared with the controls, combination therapy with berprost sodium could remarkably improve the total effective rate (odds ratio 4.21, 95% confidence interval [CI]: 2.87 to 7.25) and reduce 24 hours proteinuria (mean difference [MD] -1.03, 95% CI: -1.26 to -0.8), serum creatinine (MD -18.39; 95% CI: -27.81 to -8.98), blood urea nitrogen (MD -1.43,95% CI: -1.94 to -0.92), serum total cholesterol (MD -1.24; 95% CI: -1.36 to -1.11), and triglyceride (MD -0.69; 95% CI: -1.03 to -0.35), and increase serum albumin (MD 4.96, 95% CI: 2.98 to 6.93). But the adverse effects of dizziness and headache were higher (RD = 0.05. 95% CI: 0.02 to 0.08).

CONCLUSION

For NS patients, combination therapy with beraprost sodium can achieve higher clinical efficacy and significant improvement in renal function than conventional therapy.

Obstructive nephropathy and molecular pathophysiology of renal interstitial fibrosis

The kidneys play a key role in maintaining total body homeostasis. The complexity of this task is reflected in the unique architecture of the organ. Ureteral obstruction greatly affects renal physiology by altering hemodynamics, changing glomerular filtration and renal metabolism, and inducing architectural malformations of the kidney parenchyma, most importantly renal fibrosis. Persisting pathological changes lead to chronic kidney disease, which currently affects ∼10% of the global population and is one of the major causes of death worldwide. Studies on the consequences of ureteral obstruction date back to the 1800s. Even today, experimental unilateral ureteral obstruction (UUO) remains the standard model for tubulointerstitial fibrosis. However, the model has certain limitations when it comes to studying tubular injury and repair, as well as a limited potential for human translation. Nevertheless, ureteral obstruction has provided the scientific community with a wealth of knowledge on renal (patho)physiology. With the introduction of advanced omics techniques, the classical UUO model has remained relevant to this day and has been instrumental in understanding renal fibrosis at the molecular, genomic, and cellular levels. This review details key concepts and recent advances in the understanding of obstructive nephropathy, highlighting the pathophysiological hallmarks responsible for the functional and architectural changes induced by ureteral obstruction, with a special emphasis on renal fibrosis.

S1PR2/Wnt3a/RhoA/ROCK1/β-catenin signaling pathway promotes diabetic nephropathy by inducting endothelial mesenchymal transition and impairing endothelial barrier function

AIMS

Hyperglycemia and hyperlipidemia are key factors in the pathogenesis of diabetic nephropathy (DN), and renal fibrosis is the most common pathway leading to the disease. Endothelial mesenchymal transition (EndMT) is a crucial mechanism for the production of myofibroblasts, and impaired endothelial barrier function is one of the mechanisms for the generation of microalbuminuria in DN. However, the specific mechanisms behind these are not yet clear.

MAIN METHODS

Protein expression was detected by immunofluorescence, immunohistochemistry and Western blot. Knocking down or pharmacological inhibition of S1PR2 were used to inhibit Wnt3a, RhoA, ROCK1, β-catenin, and Snail signaling. Changes in cell function were analyzed by CCK-8 method, cell scratching assay, FITC-dextran permeability assay, and Evans blue staining.

KEY FINDINGS

Consistent with increased gene expression of S1PR2 in DN patients and mice with kidney fibrosis disease, S1PR2 expression was significantly increased in glomerular endothelial cells of DN mice and HUVEC cells treated with glucolipids. Knocking down or pharmacological inhibition of S1PR2 significantly decreased the expression of Wnt3a, RhoA, ROCK1, and β-catenin in endothelial cells. Furthermore, inhibition of S1PR2 in vivo reversed EndMT and endothelial barrier dysfunction in glomerular endothelial cells. Inhibition of S1PR2 and ROCK1 in vitro also reversed EndMT and endothelial barrier dysfunction in endothelial cells.

SIGNIFICANCE

Our results suggest that the S1PR2/Wnt3a/RhoA/ROCK1/β-catenin signaling pathway is involved in the pathogenesis of DN by inducing EndMT and endothelial barrier dysfunction.

Clinical Relevance of Computationally Derived Attributes of Peritubular Capillaries from Kidney Biopsies

Key Points

Computational image analysis allows for the extraction of new information from whole-slide images with potential clinical relevance. Peritubular capillary (PTC) density is decreased in areas of interstitial fibrosis and tubular atrophy when measured in interstitial fractional space. PTC shape (aspect ratio) is associated with clinical outcome in glomerular diseases.

Background

The association between peritubular capillary (PTC) density and disease progression has been studied in a variety of kidney diseases using immunohistochemistry. However, other PTC attributes, such as PTC shape, have not been explored yet. The recent development of computer vision techniques provides the opportunity for the quantification of PTC attributes using conventional stains and whole-slide images.

Methods

To explore the relationship between PTC characteristics and clinical outcome, n =280 periodic acid–Schiff-stained kidney biopsies (88 minimal change disease, 109 focal segmental glomerulosclerosis, 46 membranous nephropathy, and 37 IgA nephropathy) from the Nephrotic Syndrome Study Network digital pathology repository were computationally analyzed. A previously validated deep learning model was applied to segment cortical PTCs. Average PTC aspect ratio (PTC major to minor axis ratio), size (PTC pixels per PTC segmentation), and density (PTC pixels per unit cortical area) were computed for each biopsy. Cox proportional hazards models were used to assess associations between these PTC parameters and outcome (40% eGFR decline or kidney failure). Cortical PTC characteristics and interstitial fractional space PTC density were compared between areas of interstitial fibrosis and tubular atrophy (IFTA) and areas without IFTA.

Results

When normalized PTC aspect ratio was below 0.6, a 0.1, increase in normalized PTC aspect ratio was significantly associated with disease progression, with a hazard ratio (95% confidence interval) of 1.28 (1.04 to 1.59) (P = 0.019), while PTC density and size were not significantly associated with outcome. Interstitial fractional space PTC density was lower in areas of IFTA compared with non-IFTA areas.

Conclusions

Computational image analysis enables quantification of the status of the kidney microvasculature and the discovery of a previously unrecognized PTC biomarker (aspect ratio) of clinical outcome.

Beraprost Sodium Delays the Decline of Glomerular Filtration Rate in Patients with Diabetic Nephropathy: A Retrospective Study

INTRODUCTION

To investigate the reno-protective effect of beraprost sodium (BPS) in patients with diabetic nephropathy (DN).

METHODS

We retrospectively analyzed patients with DN hospitalized in China-Japan Friendship Hospital from January 2015 to December 2021 who received combination of conventional treatment and BPS (120 ug/day) therapy. We selected patients with DN matched in age and estimated glomerular filtration rate (eGFR) as controls, who received only conventional therapy. Baseline information and clinical variables at each follow-up visit were collected from all patients. The changes of clinical variables were compared between the two groups before and after treatment.

RESULTS

A total of 50 patients with DN met the inclusion and exclusion criteria, with 25 patients in each group. The baseline characteristics of the two groups have no significant difference (p > 0.05). Serum albumin levels after treatment were improved in both groups, but the improvement was statistically significant only in BPS group (35.5-39.8 g/l, p < 0.001). The eGFR worsened significantly in both groups (p = 0.009 and p = 0.001). However, the decline of eGFR was less in BPS group than that in control group (- 9.8 vs. - 16.7 ml/min/1.73 m², p = 0.037). In the subgroup analysis, 30 patients received 3-12 months treatment and 20 patients received more than 12 months treatment. During the 3-12 months treatment period, serum creatinine and eGFR in the control group were significantly worsened compared with those before treatment (p = 0.019 and p = 0.03), but in the BPS group they were relatively stable (p > 0.05). After more than 12 months treatment, although the serum creatinine and eGFR were significantly worsened in both groups (p < 0.05), the decline of eGFR was less in BPS group than that in control group (- 10.1 vs. - 25.9 ml/min/1.73 m², p = 0.045).

CONCLUSIONS

Combination of conventional treatment and BPS therapy delays the decline of eGFR in patients with DN in the long term.

Kidney-Targeted Drug Delivery System Based on Metformin-Grafted Chitosan for Renal Fibrosis Therapy

Our previous study demonstrated that metformin plays an anti-fibrotic role in addition to its hypoglycemic effect. Worryingly, it often requires more than 5 times the hypoglycemic dose to achieve a satisfactory anti-fibrotic effect, which greatly increases the risk of systemic acidosis caused by metformin overdose. Low-molecular-weight chitosan (LMWC) has natural kidney-targeting properties and good biocompatibility and degradability. Thus, we synthesized a novel carrier metformin-grafted chitosan (CS-MET) based on an imine reaction between oxidized chitosan and metformin. Then, GFP was recruited to form GFP-loaded CS-MET nanoparticles (CS-MET/GFP NPs) with controllable particle size. We hypothesized that CS-MET/GFP NPs would enrich in the kidney and be absorbed by HK-2 cells via megalin-mediated endocytosis by intravenous injection, which may avoid systemic acidosis caused by metformin overdose. Subsequently, the nanoparticle ruptures and releases metformin to exert its anti-apoptotic, anti-inflammatory, and anti-fibrotic effects. Our results showed that CS-MET/GFP NPs have great transfection efficiency and could enter HK-2 cells mainly through megalin-mediated endocytosis. Compared to the free metformin, CS-MET/GFP NPs showed similar anti-apoptotic ability but better therapeutic effects on cellular inflammation and fibrosis in vitro. On the other hand, CS-MET/GFP NPs showed great kidney-targeting ability and superior anti-apoptotic, anti-inflammatory, and anti-fibrotic effects in vivo.

Evaluation of Renal Blood Flow in Dogs during Short-Term Human-Dose Epoprostenol Administration Using Pulsed Doppler and Contrast-Enhanced Ultrasonography

Simple Summary

Since there is a lack of information regarding how epoprostenol, a prostacyclin, affects canine renal blood flow (RBF), we investigated the effects of short-term administration of epoprostenol at human doses of 2, 5, and 10 ng/kg/min intravenously for 20 min on RBF in six healthy dogs under anesthesia. The effects of short-term administration were investigated. As the dose of epoprostenol increased, peak systolic and end diastolic velocities of the renal arteries, maximum and minimum venous flow velocities of the interlobular and renal veins, and heart rate all tended to increase. However, these increases were not significant. These results indicate that the administration of human doses of epoprostenol to dogs does not produce significant changes in renal or systemic circulation.

Abstract

Prostacyclin is an in vivo bioactive substance that regulates renal blood flow (RBF). Information regarding how epoprostenol, a prostacyclin preparation, affects RBF in dogs is lacking. We investigated the effects of short-term epoprostenol administration on RBF in six healthy dogs under anesthesia by administering it intravenously at human doses—2, 5, and 10 ng/kg/min for 20 min. RBF was evaluated before and during epoprostenol administration using pulsed Doppler ultrasonography, and renal perfusion was evaluated using contrast-enhanced ultrasonography. Effects on renal and systemic circulation were evaluated by measuring systolic arterial, mean arterial, diastolic arterial, pulmonary arterial, mean right atrial, and pulmonary capillary wedge pressures; heart rate; and cardiac output. Kruskal–Wallis and Bonferroni multiple comparison tests and Spearman’s rank correlation coefficient were used for statistical analyses. As epoprostenol dosage increased, the peak systolic and end diastolic velocity of the renal artery, maximum and minimum venous flow velocities of the interlobular and renal veins, and heart rate all tended to increase, although not significantly. Our results indicate that human-dose epoprostenol administration in dogs does not cause significant changes in renal or systemic circulation. However, the human doses used may have been too low to produce a clinical effect in dogs.

MicroRNA miR-4709-3p targets Large Tumor Suppressor Kinase 2 (LATS2) and induces obstructive renal fibrosis through Hippo signaling

Obstructive renal fibrosis is the consequence of abnormal extracellular matrix assembly, which eventually results in renal failure, acute, and end‑stage renal infection. MicroRNAs (miRNAs), a particular category of small RNAs, modulate the expression of genes post-transcriptionally and regulate biological activities, including fibrogenesis. The study probed to estimate the key functions of miR-4709-3p in obstructive renal fibrosis. This investigation used TGF-β1 stimulated HK-2 in-vitro model, unilateral ureteral occlusion (UUO) mice model, and human Diabetic nephropathy (DN) and Renal interstitial fibrosis (RIF) specimens to depict the abundance of the miR-4709-3p level using FISH and RT-qPCR. MiR-4709-3p mimics and inhibitors were utilized to evaluate the functions of miR-4709-3p in-vitro. Luciferase assay was exploited to verify miR-4709-3p and LATS2 3'UTR binding. Finally, to depict the functions of miR-4709-3p in-vivo, the UUO model was injected with miR-4709-3p inhibitors. Results exhibited the upregulation of miR-4709-3p in UUO-induced in-vivo model, TGF-β1 stimulated HK-2, and human RIF and DN samples. Moreover, it was determined that modulating miR-4709-3p regulated the level of fibrosis markers. Luciferase assay miR-4709-3p modulates renal fibrosis by targeting LATS2. Finally, it was found that miR-4709-3p regulates obstructive renal fibrosis through the Hippo signaling pathway. Overall, the study concludes that aberrant miR-4709-3p expression plays an essential function in the renal fibrosis progression, and miR-4709-3p overexpression could advance obstructive renal fibrosis via LATS2 targeting in Hippo signaling pathway. Therefore, miR-4709-3p inhibition may be a potential renal fibrosis therapy target.

Defining therapeutic targets for renal fibrosis: Exploiting the biology of pathogenesis

Renal fibrosis is a failed wound-healing process of the kidney tissue after chronic, sustained injury, which is a common pathway and pathological marker of virtually every type of chronic kidney disease (CKD), regardless of cause. However, there is a lack of effective treatment specifically targeting against renal fibrosis per se to date. The main pathological feature of renal fibrosis is the massive activation and proliferation of renal fibroblasts and the excessive synthesis and secretion of extracellular matrix (ECM) deposited in the renal interstitium, leading to structural damage, impairment of renal function, and eventually end-stage renal disease. In this review, we summarize recent advancements regarding the participation and interaction of many types of kidney residents and infiltrated cells during renal fibrosis, attempt to comprehensively discuss the mechanism of renal fibrosis from the cellular level and conclude by highlighting novel therapeutic targets and approaches for development of new treatments for patients with renal fibrosis.

Purine adducts as a presumable missing link for aristolochic acid nephropathy-related cellular energy crisis, potential anti-fibrotic prevention and treatment

Aristolochic acid nephropathy is a progressive exposome-induced disease characterized by tubular atrophy and fibrosis culminating in end-stage renal disease and malignancies. The molecular mechanisms of the energy crisis as a putative cause of fibrosis have not yet been elucidated. In light of the fact that aristolochic acid forms DNA and RNA adducts by covalent binding of aristolochic acid metabolites to exocyclic amino groups of (deoxy)adenosine and (deoxy)guanosine, we hypothesize here that similar aristolochic acid adducts may exist with other purine-containing molecules. We also provide new insights into the aristolochic acid-induced energy crisis and presumably a link between already known mechanisms. In addition, an overview of potential targets in fibrosis treatment is provided, which is followed by recommendations on possible preventive measures that could be taken to at least postpone or partially alleviate aristolochic acid nephropathy.

The Roles of Various Prostaglandins in Fibrosis: A Review

Organ fibrosis is a common pathological result of various chronic diseases with multiple causes. Fibrosis is characterized by the excessive deposition of extracellular matrix and eventually leads to the destruction of the tissue structure and impaired organ function. Prostaglandins are produced by arachidonic acid through cyclooxygenases and various prostaglandin-specific synthases. Prostaglandins bind to homologous receptors on adjacent tissue cells in an autocrine or paracrine manner and participate in the regulation of a series of physiological or pathological processes, including fibrosis. This review summarizes the properties, synthesis, and degradation of various prostaglandins, as well as the roles of these prostaglandins and their receptors in fibrosis in multiple models to reveal the clinical significance of prostaglandins and their receptors in the treatment of fibrosis.

The effects of beraprost sodium on renal function and cardiometabolic profile in patients with diabetes mellitus: a systematic review and meta-analysis of clinical trials

PURPOSE

This systematic review and meta-analysis aimed to assess renal function and cardiometabolic biomarkers after treatment with beraprost sodium in patients with diabetes mellitus.

METHODS

We systemically searched PubMed, Embase, Scopus, Web of Science, and Cochrane Library up to August 2020. Statistical heterogeneities were computed using Cochrane's Q test and I² test. A fixed- or random-effects model was used to calculate the weighted mean difference (WMD) and corresponding 95% confidence intervals (CI).

RESULTS

From 341citations, seven trials were included into our meta-analysis. Our findings demonstrated that beraprost sodium intake significantly decreased blood urea nitrogen (BUN) (WMD = -5.62, 95% CI [-8.49, -2.74], P < 0.001) and cystatin C (WMD = -0.57, 95% CI [-0.68, -0.46], P < 0.001). Beraprost sodium intake had no significant effect on fasting blood sugar (FBS), hemoglobin A1c (HbA1c), cholesterol (TC), triglycerides (TG), HDL-C, LDL-C, systolic blood pressure (SBP), diastolic blood pressure (DBP), and creatinine (Cr) in patients with diabetes receiving beraprost sodium in comparison with the controls.

CONCLUSION

Our meta-analysis revealed that beraprost sodium administration significantly decreased BUN and cystatin C levels in patients with diabetes. However, no significant effect was observed on the cardiometabolic profile.

The renal microcirculation in chronic kidney disease: novel diagnostic methods and therapeutic perspectives

Chronic kidney disease (CKD) affects 8–16% of the population worldwide and is characterized by fibrotic processes. Understanding the cellular and molecular mechanisms underpinning renal fibrosis is critical to the development of new therapeutics. Microvascular injury is considered an important contributor to renal progressive diseases. Vascular endothelium plays a significant role in responding to physical and chemical signals by generating factors that help maintain normal vascular tone, inhibit leukocyte adhesion and platelet aggregation, and suppress smooth muscle cell proliferation. Loss of the rich capillary network results in endothelial dysfunction, hypoxia, and inflammatory and oxidative effects and further leads to the imbalance of pro- and antiangiogenic factors, endothelial cell apoptosis and endothelial-mesenchymal transition. New techniques, including both invasive and noninvasive techniques, offer multiple methods to observe and monitor renal microcirculation and guide targeted therapeutic strategies. A better understanding of the role of endothelium in CKD will help in the development of effective interventions for renal microcirculation improvement. This review focuses on the role of microvascular injury in CKD, the methods to detect microvessels and the novel treatments to ameliorate renal fibrosis.

Small molecules against the origin and activation of myofibroblast for renal interstitial fibrosis therapy

Renal interstitial fibrosis (RIF) is a common pathological response in a broad range of prevalent chronic kidney diseases and ultimately leads to renal failure and death. Although RIF causes a high morbi-mortality worldwide, effective therapeutic drugs are urgently needed. Myofibroblasts are identified as the main effector during the process of RIF. Multiple types of cells, including fibroblasts, epithelial cells, endothelial cells, macrophages and pericytes, contribute to renal myofibroblasts origin, and lots of mediators, including signaling pathways (Transforming growth factor-β1, mammalian target of rapamycin and reactive oxygen species) and epigenetic modifications (Histone acetylation, microRNA and long non-coding RNA) are participated in renal myofibroblasts activation during renal fibrogenesis, suggesting that these mediators may be the promising targets for treating RIF. In addition, many small molecules show profound therapeutic effects on RIF by suppressing the origin and activation of renal myofibroblasts. Taken together, the review focuses on the mechanisms of the origin and activation of renal myofibroblasts in RIF and the small molecules against them improving RIF, which will provide a new insight for RIF therapy.

Spontaneous Lung Fibrosis Resolution Reveals Novel Antifibrotic Regulators

Fibroblast activation is transient in successful wound repair but persistent in fibrotic pathologies. Understanding fibroblast deactivation during successful wound healing may provide new approaches to therapeutically reverse fibroblast activation. To characterize the gene programs that accompany fibroblast activation and reversal during lung fibrosis resolution, we used RNA sequencing analysis of flow sorted Col1α1-GFP-positive and CD45-, CD31-, and CD326-negative cells isolated from the lungs of young mice exposed to bleomycin. We compared fibroblasts isolated from control mice with those isolated at Days 14 and 30 after bleomycin exposure, representing the peak of extracellular matrix deposition and an early stage of fibrosis resolution, respectively. Bleomycin exposure dramatically altered fibroblast gene programs at Day 14. Principal component and differential gene expression analyses demonstrated the predominant reversal of these trends at Day 30. Upstream regulator and pathway analyses of reversing "resolution" genes identified novel candidate antifibrotic genes and pathways. Two genes from these analyses that were decreased in expression at Day 14 and reversed at Day 30, Aldh2 and Nr3c1, were selected for further analysis. Enhancement of endogenous expression of either gene by CRISPR activation in cultured human idiopathic pulmonary fibrosis fibroblasts was sufficient to reduce profibrotic gene expression, fibronectin deposition, and collagen gel compaction, consistent with roles for these genes in fibroblast deactivation. This combination of RNA sequencing analysis of freshly sorted fibroblasts and hypothesis testing in cultured idiopathic pulmonary fibrosis fibroblasts offers a path toward identification of novel regulators of lung fibroblast deactivation, with potential relevance to understanding fibrosis resolution and its failure in human disease.

MiR-27b-3p inhibits the progression of renal fibrosis via suppressing STAT1

Renal fibrosis is a pathologic change in chronic kidney disease (CKD). MicroRNAs (miRNAs) have been shown to play an important role in the development of renal fibrosis. However, the biological role of miR-27b-3p in renal fibrosis remains unclear. Thus, this study aimed to investigate the role of miR-27b-3p in the progression of renal fibrosis. In this study, HK-2 cells were stimulated with transforming growth factor (TGF)-β1 for mimicking fibrosis progression in vitro. The unilateral ureteric obstruction (UUO)-induced mice renal fibrosis in vivo was established as well. The results indicated that the overexpression of miR-27b-3p significantly inhibited epithelial-to-mesenchymal transition (EMT) in TGF-β1-stimulated HK-2 cells, as shown by the decreased expressions of α-SMA, collagen III, Fibronectin and Vimentin. In addition, overexpression of miR-27b-3p markedly decreased TGF-β1-induced apoptosis in HK-2 cells, as evidenced by the decreased levels of Fas, active caspase 8 and active caspase 3. Meanwhile, dual-luciferase assay showed that miR-27b-3p downregulated signal transducers and activators of transcription 1 (STAT1) expression through direct binding with the 3′-UTR of STAT1. Furthermore, overexpression of miR-27b-3p attenuated UUO-induced renal fibrosis via downregulation of STAT1, α-SMA and collagen III. In conclusion, miR-27b-3p overexpression could alleviate renal fibrosis via suppressing STAT1 in vivo and in vitro. Therefore, miR-27b-3p might be a promising therapeutic target for the treatment of renal fibrosis.

Exosomes derived from GDNF-modified human adipose mesenchymal stem cells ameliorate peritubular capillary loss in tubulointerstitial fibrosis by activating the SIRT1/eNOS signaling pathway

Mesenchymal stem cells (MSCs) have emerged as ideal cell-based therapeutic candidates for the structural and functional restoration of the diseased kidney. Glial cell line-derived neurotrophic factor (GDNF) has been demonstrated to promote the therapeutic effect of MSCs on ameliorating renal injury. The mechanism may involve the transfer of endogenous molecules via paracrine factors to salvage injured cells, but these factors remain unknown.

Methods: GDNF was transfected into human adipose mesenchymal stem cells via a lentiviral transfection system, and exosomes were isolated (GDNF-AMSC-exos). Using the unilateral ureteral obstruction (UUO) mouse model and human umbilical vein endothelial cells (HUVECs) against hypoxia/serum deprivation (H/SD) injury models, we investigated whether GDNF-AMSC-exos ameliorate peritubular capillary (PTC) loss in tubulointerstitial fibrosis and whether this effect is mediated by the Sirtuin 1 (SIRT1) signaling pathway. Additionally, by using SIRT1 activators or siRNAs, the roles of the candidate mRNA and its downstream gene in GDNF-AMSC-exo-induced regulation of endothelial cell function were assessed. PTC characteristics were detected by fluorescent microangiography (FMA) and analyzed by the MATLAB software.

Results: The green fluorescent PKH67-labeled exosomes were visualized in the UUO kidneys and colocalized with CD81. GDNF-AMSC-exos significantly decreased PTC rarefaction and renal fibrosis scores in mice with UUO. In vitro studies revealed that GDNF-AMSC-exos exerted cytoprotective effects on HUVECs against H/SD injury by stimulating migration and angiogenesis as well as conferring apoptosis resistance. Mechanistically, GDNF-AMSC-exos enhanced SIRT1 signaling, which was accompanied by increased levels of phosphorylated endothelial nitric oxide synthase (p-eNOS). We also confirmed the SIRT1-eNOS interaction in HUVECs by immunoprecipitation. Furthermore, we observed a correlation of the PTC number with the SIRT1 expression level in the kidney in vivo.

Conclusion: Our study unveiled a mechanism by which exosomes ameliorate renal fibrosis: GDNF-AMSC-exos may activate an angiogenesis program in surviving PTCs after injury by activating the SIRT1/eNOS signaling pathway.

PGI2 Analog Attenuates Salt-Induced Renal Injury through the Inhibition of Inflammation and Rac1-MR Activation

Renal inflammation is known to be involved in salt-induced renal damage, leading to end-stage renal disease. This study aims to evaluate the role of inflammation in anti-inflammatory and renoprotective effects of beraprost sodium (BPS), a prostaglandin I₂ (PGI₂) analog, in Dahl salt-sensitive (DS) rats. Five-week-old male DS rats were fed a normal-salt diet (0.5% NaCl), a high-salt diet (8% NaCl), or a high-salt diet plus BPS treatment for 3 weeks. BPS treatment could inhibit marked proteinuria and renal injury in salt-loaded DS rats with elevated blood pressure, accompanied by renal inflammation suppression. Notably, high salt increased renal expression of active Rac1, followed by increased Sgk1 expressions, a downstream molecule of mineralocorticoid receptor (MR) signal, indicating salt-induced activation of Rac1-MR pathway. However, BPS administration inhibited salt-induced Rac1-MR activation as well as renal inflammation and damage, suggesting that Rac1-MR pathway is involved in anti-inflammatory and renoprotective effects of PGI₂. Based upon Rac1 activated by inflammation, moreover, BPS inhibited salt-induced activation of Rac1-MR pathway by renal inflammation suppression, resulting in the attenuation of renal damage in salt-loaded DS rats. Thus, BPS is efficacious for the treatment of salt-induced renal injury.

Inhibition of lysyl oxidase ameliorates renal injury by inhibiting CD44-mediated pericyte detachment and loss of peritubular capillaries

Renal fibrosis is a common pathological manifestation of almost all forms of kidney disease irrespective of the etiological cause. Microvascular rarefaction represents itself as an important phenomenon associated with renal fibrosis and shows strong correlation with decline in renal functions. Lysyl oxidase (LOX) catalyzes crosslinking of extracellular matrix (ECM) proteins including collagens, plays an important role in stabilization of degradation resistant matrix. Since, there seems to be a causal link between deposition of excessive ECM and microvascular rarefaction, we investigated the effects of reduction in renal fibrosis on microvascular rarefaction in acute as well as end stage kidney. We used a well-established unilateral ureteral obstruction (UUO)-induced renal fibrosis model to produce renal fibrosis in animals. We treated animals with a LOX inhibitor, β-aminopropionitrile (BAPN, 100 mg/kg, i.p.) and investigated effects on renal fibrosis and microvascular rarefaction. We observed that LOX inhibition was associated with reduction in collagen deposition in UUO-induced renal fibrosis animal model. Further, ECM normalization by LOX inhibition decreased the loss of peritubular capillaries (PTCs) in fibrotic kidney in acute study while the LOX inhibition failed to inhibit PTCs loss in end stage kidney. The results of present study suggested that inhibition of LOX reduces collagen deposition and renal fibrosis. Further, the reduction in fibrosis fails to protect from PTCs loss in chronic study suggesting the absence of strong link between reduction in fibrosis and improvement in PTCs in an end stage kidney.

Prospective analysis of the efficacy of beraprost sodium combined with alprostadil on diabetic nephropathy and influence on rennin-angiotensin system and TNF-α

Efficacy of beraprost sodium (BPS) combined with alprostadil on diabetic nephropathy (DN) and its influence on renin angiotensin system (RAS) and TNF-α were investigated. One hundred and two patients with type 2 diabetic nephropathy admitted to Weifang People's Hospital from July 2017 to January 2019 were selected and divided into two groups according to the treatment plan. Fifty patients with alprostadil were the control group and 52 patients with alprostadil combined with BPS were the combined group. Related indexes of fasting blood glucose, hemorheology, coagulation function, renal function, urine routine, liver function, renin angiotensin system and changes of TNF-α (ELISA) were observed, and the occurrence of adverse reactions of patients were recorded. The fasting blood glucose of patients in the two groups after treatment was lower than that before treatment (P<0.05). After treatment, blood viscosity, plasma viscosity and erythrocyte deformation exponent of patients in the two groups decreased (P<0.05), and the combined group was lower than the control group (P<0.05). After treatment, the average volume of fibrinogen (FIB), D dimer and platelets of the patients in the two groups decreased (P<0.05), and the combined group was lower than the control group (P<0.05). After treatment, UACR, CysC, β2-MG and α1-MG of patients decreased in the two groups (P<0.05), and the combined group was lower than the control group (P<0.05). After treatment, renin and angiotensin II of patients decreased in both groups (P<0.05). TNF-α of patients in both groups decreased after treatment (P<0.05), and the combined group was lower than the control group (P<0.05). In conclusion, compared with alprostadil, BPS combined with alprostadil can effectively improve hemodynamics, coagulation function and renal function of DN patients, and inhibit expression of RAS-related factors and TNF-α, which is a more effective method for DN treatment.