Suppressor of cytokine signaling (SOCS) 2 attenuates renal lesions in rats with diabetic nephropathy

AG1024, an IGF-1 receptor inhibitor, ameliorates renal injury in rats with diabetic nephropathy via the SOCS/JAK2/STAT pathway

Insulin-like-growth factor-1 (IGF-1) is the ligand for insulin-like growth factor-1 receptor (IGF-1R), and the roles of IGF-1/IGF-1R in diabetic nephropathy (DN) are well-characterized previously. However, the biological functions of AG1024 (an IGF-1R inhibitor) in DN remain unknown. This study investigates the roles and related mechanisms of AG-1024 in DN. The experimental DN was established via intraperitoneal injection of streptozotocin, and STZ-induced diabetic rats were treated with AG1024 (20 mg/kg/day) for 8 weeks. The 24 h proteinuria, blood glucose level, serum creatinine, and blood urea nitrogen were measured for biochemical analyses. The increase in 24 h proteinuria, blood glucose level, serum creatinine, and blood urea of DN rats were conspicuously abated by AG1024. After biochemical analyses, the renal tissue specimens were collected, and as revealed by hematoxylin and eosin staining and Masson staining, AG-1024 mitigated typical renal damage and interstitial fibrosis in DN rats. Then, the anti-inflammatory effect of AG-1024 was assessed by western blotting and ELISA. Mechanistically, AG-1024 upregulated SOCS1 and SOCS3 expression and decreased phosphorylated JAK2, STAT1, and STAT3, as shown by western blotting. Collectively, AG-1024 (an IGF-1R inhibitor) ameliorates renal injury in experimental DN by attenuating renal inflammation and fibrosis via the SOCS/JAK2/STAT pathway.

Loss of MEN1 leads to renal fibrosis and decreases HGF-Adamts5 pathway activity via an epigenetic mechanism

BACKGROUND

Renal fibrosis is a serious condition that results in the development of chronic kidney diseases. The MEN1 gene is an epigenetic regulator that encodes the menin protein and its role in kidney tissue remains unclear.

METHODS

Kidney histology was examined on paraffin sections stained with hematoxylin-eosin staining. Masson's trichrome staining and Sirius red staining were used to analyze renal fibrosis. Gene and protein expression were determined by quantitative real-time PCR (qPCR) and Western blot, respectively. Immunohistochemistry staining in the kidney tissues from mice or patients was used to evaluate protein levels. Flow cytometry was used to analyze the cell cycle distributions and apoptosis. RNA-sequencing was performed for differential expression genes in the kidney tissues of the Men1f/f and Men1∆/∆ mice. Chromatin immunoprecipitation sequencing (ChIP-seq) was carried out for identification of menin- and H3K4me3-enriched regions within the whole genome in the mouse kidney tissue. ChIP-qPCR assays were performed for occupancy of menin and H3K4me3 at the gene promoter regions. Luciferase reporter assay was used to detect the promoter activity. The exacerbated unilateral ureteral obstruction (UUO) models in the Men1f/f and Men1∆/∆ mice were used to assess the pharmacological effects of rh-HGF on renal fibrosis.

RESULTS

The expression of MEN1 is reduce in kidney tissues of fibrotic mouse and human diabetic patients and treatment with fibrotic factor results in the downregulation of MEN1 expression in renal tubular epithelial cells (RTECs). Disruption of MEN1 in RTECs leads to high expression of α-SMA and Collagen 1, whereas MEN1 overexpression restrains epithelial-to-mesenchymal transition (EMT) induced by TGF-β treatment. Conditional knockout of MEN1 resulted in chronic renal fibrosis and UUO-induced tubulointerstitial fibrosis (TIF), which is associated with an increased induction of EMT, G2/M arrest and JNK signaling. Mechanistically, menin recruits and increases H3K4me3 at the promoter regions of hepatocyte growth factor (HGF) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (Adamts5) genes and enhances their transcriptional activation. In the UUO mice model, exogenous HGF restored the expression of Adamts5 and ameliorated renal fibrosis induced by Men1 deficiency.

CONCLUSIONS

These findings demonstrate that MEN1 is an essential antifibrotic factor in renal fibrogenesis and could be a potential target for antifibrotic therapy.

Long-chain non-coding RNA UCA1 inhibits renal tubular epithelial cell apoptosis by targeting microRNA-206 in diabetic nephropathy

In this study, the inhibitory effect of long-chain non-coding RNA urothelial carcinoma associated 1 (UCA1) on renal tubular epithelial cell apoptosis by targeting microRNA (miRNA)-206 in diabetic nephropathy (DN) was investigated through DN rat model. The results showed that UCA1 expression was significantly reduced in diabetic renal tubular epithelial tissues and HG-induced HK-2 cells. UCA1 significantly inhibited HG-induced apoptosis and inflammation of renal tubular epithelial cells in HK-2 cells. In addition, UCA1 can directly act as an anti-pro-cytokine by inhibiting the expression of miR-206, and finally inhibit the apoptosis and inflammation of renal tubular epithelial cells. We conclude that UCA1 inhibits renal tubular epithelial cell apoptosis by targeting miRNA-206 in DN and can be used as a potential therapeutic target for DN.

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 3ʹUTR 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.

The Multiple Roles of Fibroblast Growth Factor in Diabetic Nephropathy

Diabetic nephropathy (DN) is a common microvascular complication in the late stages of diabetes. Currently, the etiology and pathogenesis of DN are not well understood. Even so, available evidence shows its development is associated with metabolism, oxidative stress, cytokine interaction, genetic factors, and renal microvascular disease. Diabetic nephropathy can lead to proteinuria, edema and hypertension, among other complications. In severe cases, it can cause life-threatening complications such as renal failure. Patients with type 1 diabetes, hypertension, high protein intake, and smokers have a higher risk of developing DN. Fibroblast growth factor (FGF) regulates several human processes essential for normal development. Even though FGF has been implicated in the pathological development of DN, the underlying mechanisms are not well understood. This review summarizes the role of FGF in the development of DN. Moreover, the association of FGF with metabolism, inflammation, oxidative stress and fibrosis in the context of DN is discussed. Findings of this review are expected to deepen our understanding of DN and generate ideas for developing effective prevention and treatments for the disease.

Signaling Pathways Involved in Diabetic Renal Fibrosis

Diabetic kidney disease (DKD), as the most common complication of diabetes mellitus (DM), is the major cause of end-stage renal disease (ESRD). Renal interstitial fibrosis is a crucial metabolic change in the late stage of DKD, which is always considered to be complex and irreversible. In this review, we discuss the pathological mechanisms of diabetic renal fibrosis and discussed some signaling pathways that are closely related to it, such as the TGF-β, MAPK, Wnt/β-catenin, PI3K/Akt, JAK/STAT, and Notch pathways. The cross-talks among these pathways were then discussed to elucidate the complicated cascade behind the tubulointerstitial fibrosis. Finally, we summarized the new drugs with potential therapeutic effects on renal fibrosis and listed related clinical trials. The purpose of this review is to elucidate the mechanisms and related pathways of renal fibrosis in DKD and to provide novel therapeutic intervention insights for clinical research to delay the progression of renal fibrosis.

Exploring the mechanisms underlying the therapeutic effect of Salvia miltiorrhiza in diabetic nephropathy using network pharmacology and molecular docking

The mechanisms underlying the therapeutic effect of Salvia miltiorrhiza (SM) on diabetic nephropathy (DN) were examined using a systematic network pharmacology approach and molecular docking. The Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to screen active ingredients of SM. Targets were obtained using the SwissTargetPrediction and TCMSP databases. Proteins related to DN were retrieved from the GeneCards and DisGeNET databases. A protein–protein interaction (PPI) network was constructed using common SM/DN targets in the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. The Metascape platform was used for Gene Ontology (GO) function analysis, and the Cytoscape plug-in ClueGO was used for Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Molecular docking was performed using iGEMDOCK and AutoDock Vina software. Pymol and LigPlos were used for network mapping. Sixty-six active ingredients and 189 targets of SM were found. Sixty-four targets overlapped with DN-related proteins. The PPI network revealed that AKT serine/threonine kinase 1 (AKT1), VEGFA, interleukin 6 (IL6), TNF, mitogen-activated protein kinase 1 (MAPK1), tumor protein p53 (TP53), epidermal growth factor receptor (EGFR), signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase 14 (MAPK14), and JUN were the ten most relevant targets. GO and KEGG analyses revealed that the common targets of DN and SM were mainly involved in advanced glycation end-products, oxidative stress, inflammatory response, and immune regulation. Molecular docking revealed that potential DN-related targets, including tumor necrosis factor (TNF), NOS2, and AKT1, more stably bound with salvianolic acid B than with tanshinone IIA. In conclusion, the present study revealed the active components and potential molecular therapeutic mechanisms of SM in DN and provides a reference for the wide application of SM in clinically managing DN.

Pathogenic Pathways and Therapeutic Approaches Targeting Inflammation in Diabetic Nephropathy

Diabetic nephropathy (DN) is associated with an increased morbidity and mortality, resulting in elevated cost for public health systems. DN is the main cause of chronic kidney disease (CKD) and its incidence increases the number of patients that develop the end-stage renal disease (ESRD). There are growing epidemiological and preclinical evidence about the close relationship between inflammatory response and the occurrence and progression of DN. Several anti-inflammatory strategies targeting specific inflammatory mediators (cell adhesion molecules, chemokines and cytokines) and intracellular signaling pathways have shown beneficial effects in experimental models of DN, decreasing proteinuria and renal lesions. A number of inflammatory molecules have been shown useful to identify diabetic patients at high risk of developing renal complications. In this review, we focus on the key role of inflammation in the genesis and progression of DN, with a special interest in effector molecules and activated intracellular pathways leading to renal damage, as well as a comprehensive update of new therapeutic strategies targeting inflammation to prevent and/or retard renal injury.

Danzhi Jiangtang Capsule ameliorates kidney injury via inhibition of the JAK-STAT signaling pathway and increased antioxidant capacity in STZ-induced diabetic nephropathy rats

Danzhi Jiangtang Capsule (DJC), a traditional Chinese medicinal formula, has been used clinically in treating diabetes and diabetic nephropathy (DN). We previously demonstrated that DJC is capable of improving renal function in patients and rats with DN, but the mechanisms underlying these therapeutic benefits of DJC are not quite clear yet. In this study, STZ-induced diabetic rats were orally administered DJC for 8 weeks. Fasting blood glucose, renal function indicators in the serum, renal index, and the expression of proteins related to JAK-STAT signaling pathway were evaluated at the end of the experiment. The kidneys were sliced for pathological histology. Antioxidant status was assessed by measuring SOD, LPO and MDA in serum. The expression levels of COX2, iNOS, SOCS and the phosphorylation status of JAK2, STAT1, and STAT3 in renal tissues were evaluated by Western blot analyses. IL-6, TNF-α, and MCP-1 expression levels in renal tissues were determined using double-antibody sandwich ELISA. Diabetic renal dysfunction and its associated pathologies were ameliorated by DJC treatment. DJC significantly reversed the high expression of COX2 and iNOS in renal tissues. Furthermore, DJC inhibited the JAK2-STAT1/STAT3-SOCS3 signaling pathway, resulting in decreased concentrations of IL-6, TNF-α, and MCP-1. Moreover, the oxidant status in the kidney was substantially ameliorated by DJC treatment. In conclusion, the ability of DJC to ameliorate diabetic renal dysfunction and the associated pathologies of this disease might be due to its antioxidant capacity and suppression of the JAK2-STAT1/STAT3 cascade.

Diabetes in Pregnancy and MicroRNAs: Promises and Limitations in Their Clinical Application

Maternal diabetes is associated with an increased risk of complications for the mother and her offspring. The latter have an increased risk of foetal macrosomia, hypoglycaemia, respiratory distress syndrome, preterm delivery, malformations and mortality but also of life-long development of obesity and diabetes. Epigenetics have been proposed as an explanation for this long-term risk, and microRNAs (miRNAs) may play a role, both in short- and long-term outcomes. Gestation is associated with increasing maternal insulin resistance, as well as β-cell expansion, to account for the increased insulin needs and studies performed in pregnant rats support a role of miRNAs in this expansion. Furthermore, several miRNAs are involved in pancreatic embryonic development. On the other hand, maternal diabetes is associated with changes in miRNA both in maternal and in foetal tissues. This review aims to summarise the existing knowledge on miRNAs in gestational and pre-gestational diabetes, both as diagnostic biomarkers and as mechanistic players, in the development of gestational diabetes itself and also of short- and long-term complications for the mother and her offspring.

Targeting inflammation in diabetic nephropathy: a tale of hope

INTRODUCTION

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Beyond the new anti-diabetic drugs that possess markedly cardiovascular and renal protective effects, no novel direct therapies for DN have become available on the market in the last twenty years. Recently well-designed clinical trials for the treatment of DN, with attractive pathogenetic rationale, e.g. bardoxolone and atrasentan, were canceled or stopped because of safety concerns or lack of reaching the end points, respectively.

AREAS COVERED

In this review, we focus on the involvement of inflammation in the pathogenesis of DN. We update information from recent experimental and clinical studies that reported beneficial effects of several agents targeting chemokines, cytokines, transcription factors and kinases as well as several compounds with anti-inflammatory properties on DN.

EXPERT OPINION

Inflammation plays a key role in the DN progression. Preclinical studies have identified several anti-inflammatory molecules that effective decrease albuminuria and/or proteinuria. However, limited clinical trials in humans have been performed to confirm these results. Inhibitors of CCL2/CCR2, IL-1β and JAK/STAT pathways, and Nrf2 inducers are promising therapeutic options to improve the renal outcome of patients with DN, but appropriate clinical trials are necessary.

Inhibitor of IGF1 receptor alleviates the inflammation process in the diabetic kidney mouse model without activating SOCS2

Objective

To explore the anti-inflammatory mechanism of IGF1R inhibitor in diabetic nephropathy.

Methods

C57/BL6 mice were reared with high-fat diet for 8 weeks, then were injected 30 mg/kg streptozotocin intraperitoneally to induce type 2 diabetes. After 8 weeks, the type 2 diabetes nephropathy model was successfully set up the different drugs were administrated to mice with diabetes (insulin 1-2 U/day, benazepril 10 mg/kg per day intragastrically, IGF-1R inhibitor 30 mg/kg per day intragastrically). After 8 weeks drugs administration, all mice were collected the kidney tissue, measured levels of inflammatory factor (F4/80, TLR4and CD68) and fibrosis markers(αSMA, E-cadherin and SR) using immunohistochemistry and in situ hybridization.

Results

The type 2 diabetes nephropathy model was built successfully, which along with increased urinary protein excretion rate and increased inflammatory infiltration, and the correlation was characterized by increased CD68⁺, F4/80⁺ cells and increased TLR4, αSMA, SR expression. IGF-1R inhibitors reversed this changes, but benazepril and insulin were without significant changes. The insulin decreased the expression level of IGF-1, and increased the levels of suppressor of cytokine signaling 2 (SOCS2). Benazepril and IGF-1R inhibitor were no significant changes like insulin.

Conclusion

Inhibition of IGF1R was a more effective choice for inflammation treatment than Ben or Ins in diabetic kidney disease (DKD). The IGF1R inhibitor blocked pathological changes induced by the over-expression of IGF1 in DKD without up-regulating SOCS2 protein levels.

Suppressor of cytokine signaling 2-12 regulates antimicrobial peptides and ecdysteroid signaling pathways in Bombyx mori (Dazao)

Suppressors of cytokine signaling (SOCS) are a potent negative regulator of diverse cytokine-related responses to maintain various physiological processes in animals. Here, we obtained the SOCS2-12 gene sequence of Bombyx mori (Dazao) (BmSOCS2-12) from the National Center for Biotechnology Information (NCBI) to study its expression profile in different tissues, as well as in the immune tissues following larval exposure to pathogens. Further, we investigated the role of BmSOCS2-12 in producing antimicrobial peptides (AMPs) and as a regulator of ecdysteroid signaling transduction. The quantitative real-time PCR analysis revealed unequal transcript levels of BmSOCS2-12 in the different tissues, however the gene's expression was highest in those of fat body and hemocyte. The challenge with pathogens significantly upregulated the transcript level of BmSOCS2-12 in both fat body and hemocyte when compared with the control. By contrast, recombinant BmSOCS2-12 protein injections strongly suppressed the expression of AMPs, while the knockdown of BmSOCS2-12 by double-stranded RNA enhanced their production. Administration of 20-hydroxyecdysone significantly downregulated the BmSOCS2-12 expression in fat body, and the depletion of BmSOCS2-12 enhanced the transcript levels of 20-hydroxyecdysone-responsive genes at 48 h. Altogether, BmSOCS2-12 may have multiple functional roles in the physiology of B. mori (Dazao), since it negatively regulates the expression of AMPs and ecdysteroid signaling transduction.

SOCS2 overexpression alleviates diabetic nephropathy in rats by inhibiting the TLR4/NF-κB pathway

Suppressor of cytokine signaling 2 (SOCS2) was reported to be involved in the development of Diabetic Nephropathy (DN). However, its underlying mechanism remains undefined. Western blot was carried out to determine the expressions of SOCS2, Toll-like receptors 4 (TLR4) and nuclear factor kappa B (NF-κB) pathway-related proteins in DN patients, streptozotocin (STZ)-induced DN rats and high glucose (HG)-stimulated podocytes. The effects of SOCS2 overexpression on renal injury, the inflammatory cytokines production, renal pathological changes, apoptosis and the TLR4/NF-κB pathway in DN rats or HG-stimulated podocytes were investigated. TLR4 antagonist TAK-242 and NF-κB inhibitor PDTC were used to confirm the functional mechanism of SOCS2 overexpression in HG-stimulated podocytes. SOCS2 was down-regulated, while TLR4 and NF-κB were up-regulated in renal tissues of DN patients and DN rats. Ad-SOCS2 infection alleviated STZ-induced renal injury and pathological changes and inhibited STZ-induced IL-6, IL-1β and MCP-1 generation and activation of the TLR4/NF-κB pathway in DN rats. SOCS2 overexpression attenuated apoptosis, suppressed the inflammatory cytokines expression, and inactivated the TLR4/NF-κB pathway in HG-stimulated podocytes. Suppression of the TLR4/NF-κB pathway enhanced the inhibitory effect of SOCS2 overexpression on apoptosis and inflammatory cytokines expressions in HG-stimulated podocytes. SOCS2 overexpression alleviated the development of DN by inhibiting the TLR4/NF-κB pathway, contributing to developing new therapeutic strategies against DN.

Nano-sized carriers in gene therapy for renal fibrosis in vivo

Renal fibrosis is the final common pathway leading to end-stage renal failure regardless of underlying initial nephropathies. No specific therapy has been established for renal fibrosis. Gene therapy is a promising strategy for the treatment of renal fibrosis. Nano-sized carriers including viral vectors and non-viral vectors have been shown to enhance the delivery and treatment effects of gene therapy for renal fibrosis in vivo. This review focuses on the mechanisms of renal fibrosis and the in vivo technologies and methodologies of nano-sized carriers in gene therapy for renal fibrosis. RESPONSIBLE EDITOR Alexander Seifalian Director of Nanotechnology & Regenerative Medicine Ltd., The London BioScience Innovation Centre, London, UNITED KINGDOM.

A Role of Suppressor of Cytokine Signaling 2 in the Regulation of Ecdysteroid Signaling Pathway in Procambarus clarkii

A suppressor of cytokine signaling 2 (SOCS-2) homolog was identified from the red crayfish Procambarus clarkii. Phylogenic analysis showed that P. clarkii SOCS-2 (Pc-SOCS-2) was very similar to that of invertebrates. The sequence contains a central SH2 domain, a conserved SOCS box, and a variable N-terminal domain. Real-time polymerase chain reaction showed that Pc-SOCS-2 mRNA level was higher in muscle and heart than in the other tissues examined. A 40-kDa recombinant protein was successfully expressed and purified from Escherichia coli cells as confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Pc-SOCS-2 was significantly downregulated in the hepatopancreas after 20-hydroxyecdysone injection. Knockdown of Pc-SOCS-2 gene by small interfering RNA transfection in the hepatopancreas increased the expression levels of 20-hydroxyecdysone-responsive genes at 48 hr. Taken together, these results suggest that Pc-SOCS-2 is a negative regulator of ecdysteroid signaling transduction.

Microbubbles and Ultrasound: Therapeutic Applications in Diabetic Nephropathy

Diabetic nephropathy (DN) remains one of the most common causes of end-stage renal disease. Current therapeutic strategies aiming at optimization of serum glucose and blood pressure are beneficial in early stage DN, but are unable to fully prevent disease progression. With the limitations of current medical therapies and the shortage of available donor organs for kidney transplantation, the need for novel therapies to address DN complications and prevent progression towards end-stage renal failure is crucial. The development of ultrasound technology for non-invasive and targeted in-vivo gene delivery using high power ultrasound and carrier microbubbles offers great therapeutic potential for the prevention and treatment of DN. The promising results from preclinical studies of ultrasound-mediated gene delivery (UMGD) in several DN animal models suggest that UMGD offers a unique, non-invasive platform for gene- and cell-based therapies targeted against DN with strong clinical translation potential.

JAK inhibition and progressive kidney disease

PURPOSE OF REVIEW

To review the role of Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling in the progression of chronic kidney diseases.

RECENT FINDINGS

The JAK-STAT pathway transmits signals from extracellular ligands, including many cytokines and chemokines. While these responses are best characterized in lymphoid cells, they also occur in kidney cells such as podocytes, mesangial cells, and tubular cells. JAK-STAT expression and signaling abnormalities occur in humans and animal models of different chronic kidney diseases. Enhanced expression and augmented activity of JAK1, JAK2, and STAT3 promote diabetic nephropathy and their inhibition appears to reduce the disease. Activation of JAK-STAT signaling in autosomal dominant polycystic kidney disease may play an important role in cyst growth. Activation of JAK-STAT signaling promotes HIV-associated nephropathy and may also participate in the tubular responses to chronic obstructive uropathy. On the basis of data from experimental models, inhibition of JAK-STAT signaling, via increased expression of the suppressors of cytokine signaling proteins or pharmacologic inhibition of JAK and STAT proteins, could play a therapeutic role in multiple chronic kidney diseases.

SUMMARY

Activation of the JAK-STAT pathway appears to play a role in the progression of some chronic kidney diseases. More work is needed to determine the specific role the pathway plays in individual diseases.