MicroRNA-10 negatively regulates inflammation in diabetic kidney via targeting activation of the NLRP3 inflammasome

Peptide loaded self-healing hydrogel promotes diabetic skin wound healing through macrophage orchestration and inflammation inhibition

Chronic wound is one of the complications of diabetes, and its difficult cure results in increased disability rate and mortality rate, which brings serious psychological and economic burden to patients. Excessive inflammation is one of the key reasons for poor tissue healing in chronic diabetic wounds. Herewith, the development of wound dressings with anti-inflammation and promoting tissue repair is of great significance for the treatment of chronic diabetic wounds. In this work, the Ac2-26 (Ac) peptide was loaded into the hyaluronic acid (HA) complex hydrogel for diabetic wound therapy. The hydrogel containing Ac had good mechanical properties, self-healing properties, and adhesion. It could down-regulate the M1/M2 phenotype of macrophages effectively, thereby promoting collagen type Ⅲ (COL-Ⅲ) secretion and migration of L929 and angiogenesis of HUVECs. Furthermore, the hydrogel containing Ac could restore the oxidative phosphorylation process and down-regulated toll-like receptor signaling pathway and inflammatory gene expression in the pathological environment of diabetes, showing a superior anti-inflammatory effect to ultimately promote the collagen deposition and angiogenesis in tissues for wounds repair. The HA complex hydrogel containing Ac demonstrated a good potential for clinical application in diabetic wound repair.

Unfolded protein response-activated NLRP3 inflammasome contributes to pyroptotic and apoptotic podocyte injury in diabetic kidney disease via the CHOP-TXNIP axis

BACKGROUND

Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease and end-stage renal disease worldwide. Podocyte injury and death is a key event in DKD progression. Emerging evidence has indicated that crosstalk between unfolded protein response (UPR) and NLR family pyrin domain containing 3 (NLRP3) inflammasome plays an essential role in DKD progression. However, the involvement of these pathways in podocyte injury and death during DKD remains unclear.

RESULTS

Here, we found that inositol-requiring enzyme 1 (IRE1) and protein kinase RNA-like ER kinase (PERK) branches of the UPR, NLRP3 inflammasome, and apoptosis were activated in podocytes under DKD and high glucose (HG) conditions. In vitro, inducing ER stress by thapsigargin, and IRE1 or PERK overexpression upon HG treatment stimulated NLRP3 inflammasome-mediated pyroptosis and apoptosis, whereas inhibiting IRE1 or PERK suppressed them. Importantly, we discovered that the newly identified NLRP3-binding partner, thioredoxin-interacting protein (TXNIP), upon activation by the transcription factor (TF) PERK/CCAAT-enhancer-binding protein homologous protein (CHOP), served as a link between IRE1 or PERK branches with NLRP3 inflammasome-mediated pyroptosis and apoptosis. TXNIP expression was promoted in podocytes from DKD patients and db/db mice, as well as in HG-exposed conditionally immortalized human podocyte (HPC). In HG-exposed HPC, IRE1 or PERK overexpression upregulated TXNIP expression, while IRE1 or PERK inhibition downregulated it. TXNIP or CHOP silencing both inhibited HG-upregulated TXNIP, further blocking NLRP3 inflammasome-mediated pyroptosis and apoptosis. Furthermore, NLRP3 overexpression aggravated HG-induced pyroptosis and apoptosis, whereas additional TXNIP silencing reversed them without affecting IRE1 or PERK branches.

CONCLUSION

In conclusion, our results suggested that UPR/NLRP3 inflammasome-mediated pyroptosis/apoptosis pathway was involved in diabetic podocyte injury, and that targeting the CHOP-TXNIP axis may serve as a promising therapeutic target for DKD.

Crosstalk between microRNA and inflammation; critical regulator of diabetes

A growing body of evidence indicates that microRNAs (miRNAs may be used as biomarkers for the diagnosis, prognosis, and treatment of diabetes, given their changed expression profile as the disease progresses. There is growing interest in using individual miRNAs or whole miRNA clusters linked to diabetes as therapeutic targets because of their abnormal expression and functioning. In diabetes, miRNAs are also involved in inflammatory and immunological responses. Additionally, the inflammatory response controls the generation, processing, and stability of pre- or mature miRNAs and miRNA biogenesis. With a comprehensive grasp of molecular biological activities and the signaling axis, this review emphasizes the critical functions of miRNAs in inflammatory and immunological processes in diabetes. We further emphasized the potential role of these miRNAs in controlling inflammation associated with diabetes. This assessment will direct the shift from many studies to practical applications for tailored diabetes treatment and assist in identifying new therapeutic targets and approaches.

PDIA4 targets IRE1α/sXBP1 to alleviate NLRP3 inflammasome activation and renal tubular injury in diabetic kidney disease

The role of ER stress in the pathogenesis of diabetic kidney diseases (DKD) remains unclear. We employed bioinformatics to identify the UPR pathway activation, inflammation, and programmed cell death patterns in diabetic tubules. Levels of IRE1α/sXBP1 signaling, NLRP3 inflammasome activity and pyroptosis in tubular cells under high glucose conditions were measured. IRE1α knockdown was used to determine its role in glucose-triggered activation of the NLRP3 inflammasome and pyroptosis. PDIA4 overexpression and silencing were used to assess its impact on the IRE1α/sXBP1 pathway. The dynamic interaction among PDIA4, GRP78, and IRE1α under high glucose were analyzed using immunoprecipitation and crosslinking assays. In STZ-induced and db/db mouse models of DKD, the regulatory role of PDIA4 on IRE1α/sXBP1 signaling and diabetic tubular inflammation and injury were evaluated. Our study showed that IRE1α/sXBP1, NLRP3 inflammasome, and pyroptosis are activated in the renal tubules of DKD patients. Induction of IRE1α pathway mediated the glucose-triggered activation of the NLRP3 inflammasome and pyroptosis. Moreover, overexpression of PDIA4 decreased the activation of IRE1α/sXBP1 under high glucose conditions. High glucose leads to the release of GRP78 from IRE1α and an increased interaction between IRE1α and PDIA4. In mouse models of DKD, overexpressing PDIA4 mitigated diabetic tubular injury and inflammation, marked by decreased IRE1α/sXBP1 and NLRP3 inflammasome. In conclusion, our findings demonstrate that high glucose triggers NLRP3 inflammasome and pyroptosis via the IRE1α/sXBP1 pathway in renal tubular cells. Overexpression of PDIA4 suppresses IRE1α signaling by binding to its oligomeric form, implying a promising therapeutic intervention for DKD.

Caloric restriction exacerbates renal post-ischemic injury and fibrosis by modulating mTORC1 signaling and autophagy

OBJECTIVE

This study investigates the effects of caloric restriction (CR) on renal injury and fibrosis following ischemia-reperfusion injury (IRI), with a focus on the roles of the mechanistic/mammalian target of rapamycin complex 1 (mTORC1) signaling and autophagy.

METHODS

A mouse model of unilateral IRI with or without CR was used. Renal function was assessed through serum creatinine and blood urea nitrogen levels, while histological analysis and molecular assays evaluated tubular injury, fibrosis, mTORC1 signaling, and autophagy activation. Inducible renal tubule-specific Atg7 knockout mice and autophagy inhibitor 3-MA were used to elucidate autophagy's role in renal outcomes.

RESULTS

CR exacerbated renal dysfunction, tubular injury, and fibrosis in IRI mice, associated with suppressed mTORC1 signaling and enhanced autophagy. Rapamycin, an mTORC1 inhibitor, mimicked the effects of CR, further supporting the involvement of mTORC1-autophagy pathway. Tubule-specific Atg7 knockout and autophagy inhibitor 3-MA mitigated these effects, indicating a central role for autophagy in CR-induced renal damage. Glucose supplementation, but not branched-chain amino acids (BCAAs), alleviated CR-induced renal fibrosis and dysfunction by restoring mTORC1 activation. Finally, we identified leucyl-tRNA synthetase 1 (LARS1) as a key mediator of nutrient sensing and mTORC1 activation, demonstrating its glucose dependency under CR conditions.

CONCLUSION

Our study provides novel insights into the interplay between nutrient metabolism, mTORC1 signaling, and autophagy in IRI-induced renal damages, offering potential therapeutic targets for mitigating CR-associated complications after renal IRI.

F2RL1 Inhibition Alleviates Lipotoxicity-Induced Kidney Injury Through the Hippo Pathway in Diabetic Kidney Disease

Diabetic kidney disease (DKD), which is emerging as a pervasive global health concern and a considerable economic burden, is characterized by a detrimental effect on renal function and structure. Recent research indicates that the progression of DKD is facilitated by lipotoxic injury to tubular epithelial cells (TECs). However, the specific mechanisms that contribute to this cellular damage have yet to be fully elucidated. Our results revealed a significant upregulation of F2RL1 in vivo and in vitro models, which was positively correlated with the expression of inflammatory factors. Knockdown of F2RL1 significantly reduced inflammatory response in palmitate-stimulated HK-2 cells. Mechanistically, F2RL1 might exacerbate lipotoxicity-induced DKD through the modulation of the Hippo signaling pathway. Collectively, these findings suggest that modulating F2RL1 expression may be a strategic approach to mitigate the inflammatory damage to RTECs associated with DKD, potentially through its involvement in the Hippo signaling pathway. Given these findings, F2RL1 merits consideration as a candidate therapeutic target for DKD.

miR-199a-5p aggravates renal ischemia-reperfusion and transplant injury by targeting AKAP1 to disrupt mitochondrial dynamics

Renal ischemia-reperfusion injury (IRI) is a complex pathophysiological process and a major cause of delayed graft function (DGF) after transplantation. MicroRNA (miRNA) has important roles in the pathogenesis of IRI and may represent promising therapeutic targets for mitigating renal IRI. miRNA sequencing was performed to profile microRNA expression in mouse kidneys after cold storage and transplantation (CST). Lentivirus incorporating a miR-199a-5p modulator was injected into mouse kidney in situ before syngenetic transplantation and unilateral IRI to determine the effect of miR-199a-5p in vivo. miR-199a-5p mimic or inhibitor was transfected cultured tubular cells before ATP depletion recovery treatment to examine the role of miR-199a-5p in vitro. Sequencing data and microarray showed upregulation of miR-199a-5p in mice CST and human DGF samples. Lentivirus incorporating a miR-199a-5p mimic aggravated renal IRI, and protective effects were obtained with a miR-199a-5p inhibitor. Treatment with the miR-199a-5p inhibitor ameliorated graft function loss, tubular injury, and immune response after CST. In vitro experiments revealed exacerbation of mitochondria dysfunction upon ATP depletion and repletion model in the presence of the miR-199a-5p mimic, whereas dysfunction was attenuated when the miR-199a-5p inhibitor was applied. miR-199a-5p was shown to target A-kinase anchoring protein 1 (AKAP1) by double luciferase assay and miR-199a-5p activation reduced dynamin-related protein 1 (Drp1)-s637 phosphorylation and mitochondrial length. Overexpression of AKAP1 preserved Drp1-s637 phosphorylation and reduced mitochondrial fission. miR-199a-5p activation reduced AKAP1 expression, promoted Drp1-s637 dephosphorylation, aggravated the disruption of mitochondrial dynamics, and contributed to renal IRI.NEW & NOTEWORTHY This study identifies miR-199a-5p as a key regulator in renal ischemia-reperfusion injury through microRNA sequencing in mouse models and human delayed graft function. miR-199a-5p worsens renal IRI by aggravating graft dysfunction, tubular injury, and immune response, while its inhibition shows protective effects. miR-199a-5p downregulates A-kinase anchoring protein 1 (AKAP1), reducing dynamin-related protein 1 (Drp1)-s637 phosphorylation, increasing mitochondrial fission, and causing dysfunction. Targeting the miR-199a-5p/AKAP1/Drp1 axis offers therapeutic potential for renal IRI, as AKAP1 overexpression preserves mitochondrial integrity by maintaining Drp1-s637 phosphorylation.

microRNAs in kidney diseases: Regulation, therapeutics, and biomarker potential

MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a crucial role in regulating gene expression by inhibiting the translation of their specific target messenger RNAs. To date, numerous studies have demonstrated changes in the expression of miRNAs in the kidneys throughout the progression of both acute kidney injury (AKI) and chronic kidney disease (CKD) in both human patients and experimental models. The role of specific microRNAs in the pathogenesis of kidney diseases has also been demonstrated. Further studies have elucidated the regulation of these microRNAs in diseased kidneys. Besides, certain miRNAs are detected in plasma and/or urine in kidney diseases and are potential diagnostic biomarkers. In this review, we provide an overview of recent developments in our understanding of how miRNAs contribute to kidney diseases. We also explore the potential of miRNAs as both biomarkers and therapeutic targets for these conditions, and highlight future research directions.

Review on the role of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome pathway in diabetes: mechanistic insights and therapeutic implications

This review explores the pivotal role of the nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome in the pathogenesis of diabetes and its complications, highlighting the therapeutic potential of various oral hypoglycemic drugs targeting this pathway. NLRP3 inflammasome activation, triggered by metabolic stressors like hyperglycemia, hyperlipidemia, and free fatty acids (FFAs), leads to the release of pro-inflammatory cytokines interleukin-1β and interleukin-18, driving insulin resistance, pancreatic β-cell dysfunction, and systemic inflammation. These processes contribute to diabetic complications such as nephropathy, neuropathy, retinopathy, and cardiovascular diseases (CVD). Here we discuss the various transcriptional, epigenetic, and gut microbiome mediated regulation of NLRP3 activation in diabetes. Different classes of oral hypoglycemic drugs modulate NLRP3 inflammasome activity through various mechanisms: sulfonylureas inhibit NLRP3 activation and reduce inflammatory cytokine levels; sodium-glucose co-transporter 2 inhibitors (SGLT2i) suppress inflammasome activity by reducing oxidative stress and modulating intracellular signaling pathways; dipeptidyl peptidase-4 inhibitors mitigate inflammasome activation, protecting against renal and vascular complications; glucagon-like peptide-1 receptor agonists attenuate NLRP3 activity, reducing inflammation and improving metabolic outcomes; alpha-glucosidase inhibitors and thiazolidinediones exhibit anti-inflammatory properties by directly inhibiting NLRP3 activation. Agents that specifically target NLRP3 and inhibit their activation have been identified recently such as MCC950, Anakinra, CY-09, and many more. Targeting the NLRP3 inflammasome, thus, presents a promising strategy for managing diabetes and its complications, with oral hypoglycemic drugs offering dual benefits of glycemic control and inflammation reduction. Further research into the specific mechanisms and long-term effects of these drugs on NLRP3 inflammasome activity is warranted.

Therapy Targeted to the NLRP3 Inflammasome in Chronic Kidney Disease

Background

The NLRP3 inflammasome is a cytoplasmic polymeric protein complex composed of the cytoplasmic sensor NLRP3, the apoptosis-related spot-like protein ASC, and the inflammatory protease caspase-1. NLRP3 activates and releases IL-1β through classical pathways, and IL-18 mediates inflammation and activates gasdermin-D protein to induce cellular pyroptosis. Numerous studies have also emphasized the non-classical pathway activated by the NLRP3 inflammasome in chronic kidney disease (CKD) and the inflammasome-independent function of NLRP3.

Summary

The NLRP3-targeting inflammasome and its associated pathways have thus been widely studied in models of CKD treatment, but no drug that targets NLRP3 has thus far been approved for the treatment of CKD.

Key Messages

We herein reviewed the current interventional methods for targeting the NLRP3 inflammasome in various CKD models, analyzed their underlying mechanisms of action, classified and compared them, and discussed the advantages and follow-up directions of various interventional methods. This review therefore provides novel ideas and a reference for the development of targeted NLRP3-inflammasome therapy in CKD.

Intertwined regulators: hypoxia pathway proteins, microRNAs, and phosphodiesterases in the control of steroidogenesis

Oxygen sensing is of paramount importance for maintaining cellular and systemic homeostasis. In response to diminished oxygen levels, the hypoxia-inducible factors (HIFs) orchestrate various biological processes. These pivotal transcription factors have been identified as key regulators of several biological events. Notably, extensive research from our group and others has demonstrated that HIF1α exerts an inverse regulatory effect on steroidogenesis, leading to the suppression of crucial steroidogenic enzyme expression and a subsequent decrease in steroid levels. These steroid hormones occupy pivotal roles in governing a myriad of physiological processes. Substantial or prolonged fluctuations in steroid levels carry detrimental consequences across multiple organ systems and underlie various pathological conditions, including metabolic and immune disorders. MicroRNAs serve as potent mediators of multifaceted gene regulatory mechanisms, acting as influential epigenetic regulators that modulate a broad spectrum of gene expressions. Concomitantly, phosphodiesterases (PDEs) play a crucial role in governing signal transduction. PDEs meticulously manage intracellular levels of both cAMP and cGMP, along with their respective signaling pathways and downstream targets. Intriguingly, an intricate interplay seems to exist between hypoxia signaling, microRNAs, and PDEs in the regulation of steroidogenesis. This review highlights recent advances in our understanding of the role of microRNAs during hypoxia-driven processes, including steroidogenesis, as well as the possibilities that exist in the application of HIF prolyl hydroxylase (PHD) inhibitors for the modulation of steroidogenesis.

ANKRD1 aggravates renal ischaemia‒reperfusion injury via promoting TRIM25-mediated ubiquitination of ACSL3

BACKGROUND

Renal ischaemia‒reperfusion injury (IRI) is the primary cause of acute kidney injury (AKI). To date, effective therapies for delaying renal IRI and postponing patient survival remain absent. Ankyrin repeat domain 1 (ANKRD1) has been implicated in some pathophysiologic processes, but its role in renal IRI has not been explored.

METHODS

The mouse model of IRI-AKI and in vitro model were utilised to investigate the role of ANKRD1. Immunoprecipitation-mass spectrometry was performed to identify potential ANKRD1-interacting proteins. Protein‒protein interactions and protein ubiquitination were examined using immunoprecipitation and proximity ligation assay and immunoblotting, respectively. Cell viability, damage and lipid peroxidation were evaluated using biochemical and cellular techniques.

RESULTS

First, we unveiled that ANKRD1 were significantly elevated in renal IRI models. Global knockdown of ANKRD1 in all cell types of mouse kidney by recombinant adeno-associated virus (rAAV9)-mitigated ischaemia/reperfusion-induced renal damage and failure. Silencing ANKRD1 enhanced cell viability and alleviated cell damage in human renal proximal tubule cells exposed to hypoxia reoxygenation or hydrogen peroxide, while ANKRD1 overexpression had the opposite effect. Second, we discovered that ANKRD1's detrimental function during renal IRI involves promoting lipid peroxidation and ferroptosis by directly binding to and decreasing levels of acyl-coenzyme A synthetase long-chain family member 3 (ACSL3), a key protein in lipid metabolism. Furthermore, attenuating ACSL3 in vivo through pharmaceutical approach and in vitro via RNA interference mitigated the anti-ferroptotic effect of ANKRD1 knockdown. Finally, we showed ANKRD1 facilitated post-translational degradation of ACSL3 by modulating E3 ligase tripartite motif containing 25 (TRIM25) to catalyse K63-linked ubiquitination of ACSL3, thereby amplifying lipid peroxidation and ferroptosis, exacerbating renal injury.

CONCLUSIONS

Our study revealed a previously unknown function of ANKRD1 in renal IRI. By driving ACSL3 ubiquitination and degradation, ANKRD1 aggravates ferroptosis and ultimately exacerbates IRI-AKI, underlining ANKRD1's potential as a therapeutic target for kidney IRI.

KEY POINTS/HIGHLIGHTS

Ankyrin repeat domain 1 (ANKRD1) is rapidly activated in renal ischaemia‒reperfusion injury (IRI) models in vivo and in vitro. ANKRD1 knockdown mitigates kidney damage and preserves renal function. Ferroptosis contributes to the deteriorating function of ANKRD1 in renal IRI. ANKRD1 promotes acyl-coenzyme A synthetase long-chain family member 3 (ACSL3) degradation via the ubiquitin‒proteasome pathway. The E3 ligase tripartite motif containing 25 (TRIM25) is responsible for ANKRD1-mediated ubiquitination of ACSL3.

Extracellular Vesicle Transplantation Is Beneficial for Acute Kidney Injury

Under vasculogenic conditioning, certain pro-inflammatory subsets within peripheral blood mononuclear cells (PBMCs) undergo phenotypic transformation into pro-regenerative types, such as vasculogenic endothelial progenitor cells, M2 macrophages, and regulatory T cells. These transformed cells are collectively termed regeneration-associated cells (RACs). In this study, we aimed to investigate the therapeutic efficacy of RAC-derived extracellular vesicles (RACev) compared with a vehicle-treated group in the context of renal ischemia-reperfusion injury (R-IRI). Human PBMCs were cultured with defined growth factor cocktails for seven days to harvest RACs. EV quantity and size were characterized by nanoparticle tracking analysis. Notably, the systemic injection of RACev significantly decreased serum creatinine and blood urine nitrogen at day three compared to the control group. Histologically, the treatment group showed less fibrosis in the cortex and medullary areas (p < 0.04 and p < 0.01) compared to the control group. The CD31 staining confirmed enhanced capillary densities in the treatment group compared to the control group (p < 0.003). These beneficial effects were accompanied by angiogenesis, anti-fibrosis, anti-inflammation, and anti-apoptosis RACev miR delivery to ischemic injury to control inflammatory, endothelial mesenchymal transition, and hypoxia pathways. In vivo bioluminescence analysis demonstrated a preferential accumulation of RACev in the IR-injured kidney. The systemic transplantation of RACev beneficially restored kidney function by protecting from tissue fibrosis and through anti-inflammation, angiogenesis, and anti-apoptosis miR delivery to the ischemic tissue.

miRNA-Mediated Mechanisms in the Generation of Effective and Safe Oncolytic Viruses

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression by inhibiting the translation of target transcripts. The expression profiles of miRNAs vary in different tissues and change with the development of diseases, including cancer. This feature has begun to be used for the modification of oncolytic viruses (OVs) in order to increase their selectivity and efficacy. OVs represent a relatively new class of anticancer drugs; they are designed to replicate in cancer tumors and destroy them. These can be natural viruses that can replicate within cancer tumor cells, or recombinant viruses created in laboratories. There are some concerns regarding OVs' toxicity, due to their ability to partially replicate in healthy tissues. In addition, lytic and immunological responses upon OV therapy are not always sufficient, so various OV editing methods are used. This review discusses the latest results of preclinical and clinical studies of OVs, modifications of which are associated with the miRNA-mediated mechanism of gene silencing.

Research Progress of Pyroptosis in Diabetic Kidney Disease

Pyroptosis, known as one typical mode of programmed cell death, is generally characterized by the cleaved gasdermin family (GSDMs) forming pores in the cell membrane and inducing cell rupture, and the activation of aspartate-specific proteases (caspases) has also been found during this process. Diabetic Kidney Disease (DKD) is caused by the complication of diabetes in the kidney, and the most important kidney's function, Glomerular Filtration Rate (GFR), happens to drop to less than 90% of its usual and even lead to kidney failure in severe cases. The persistent inflammatory state induced by high blood glucose implies the key pathology of DKD, and growing evidence shows that pyroptosis serves as a significant contributor to this chronic immune-mediated inflammatory disorder. Currently, the expanded discovery of GSDMs, pyroptosis, and its association with innate immunity has been more attractive, and overwhelming research is needed to sort out the implication of pyroptosis in DKD pathology. In this review, we comb both classical studies and newly founds on pyroptosis, prick off the novel awakening of pyroptosis in DKD, and center on the significance of pyroptosis in DKD treatment, aiming to provide new research targets and treatment strategies on DKD.

Integrated oral microgel system ameliorates renal fibrosis by hitchhiking co-delivery and targeted gut flora modulation

BACKGROUND

Renal fibrosis is a progressive process associated with chronic kidney disease (CKD), contributing to impaired kidney function. Active constituents in traditional Chinese herbs, such as emodin (EMO) and asiatic acid (AA), exhibit potent anti-fibrotic properties. However, the oral administration of EMO and AA results in low bioavailability and limited kidney accumulation. Additionally, while oral probiotics have been accepted for CKD treatment through gut microbiota modulation, a significant challenge lies in ensuring their viability upon administration. Therefore, our study aims to address both renal fibrosis and gut microbiota imbalance through innovative co-delivery strategies.

RESULTS

In this study, we developed yeast cell wall particles (YCWPs) encapsulating EMO and AA self-assembled nanoparticles (NPYs) and embedded them, along with Lactobacillus casei Zhang, in chitosan/sodium alginate (CS/SA) microgels. The developed microgels showed significant controlled release properties for the loaded NPYs and prolonged the retention time of Lactobacillus casei Zhang (L. casei Zhang) in the intestine. Furthermore, in vivo biodistribution showed that the microgel-carried NPYs significantly accumulated in the obstructed kidneys of rats, thereby substantially increasing the accumulation of EMO and AA in the impaired kidneys. More importantly, through hitchhiking delivery based on yeast cell wall and positive modulation of gut microbiota, our microgels with this synergistic strategy of therapeutic and modulatory interactions could regulate the TGF-β/Smad signaling pathway and thus effectively ameliorate renal fibrosis in unilateral ureteral obstruction (UUO) rats.

CONCLUSION

In conclusion, our work provides a new strategy for the treatment of renal fibrosis based on hitchhiking co-delivery of nanodrugs and probiotics to achieve synergistic effects of disease treatment and targeted gut flora modulation.

MicroRNA-10 Family Promotes Renal Fibrosis through the VASH-1/Smad3 Pathway

Renal fibrosis (RF) stands as a pivotal pathological process in the advanced stages of chronic kidney disease (CKD), and impeding its progression is paramount for delaying the advancement of CKD. The miR-10 family, inclusive of miR-10a and miR-10b, has been implicated in the development of various fibrotic diseases. Nevertheless, the precise role of miR-10 in the development of RF remains enigmatic. In this study, we utilized both an in vivo model involving unilateral ureteral obstruction (UUO) in mice and an in vitro model employing TGF-β1 stimulation in HK-2 cells to unravel the mechanism underlying the involvement of miR-10a/b in RF. The findings revealed heightened expression of miR-10a and miR-10b in the kidneys of UUO mice, accompanied by a substantial increase in p-Smad3 and renal fibrosis-related proteins. Conversely, the deletion of these two genes led to a notable reduction in p-Smad3 levels and the alleviation of RF in mouse kidneys. In the in vitro model of TGF-β1-stimulated HK-2 cells, the co-overexpression of miR-10a and miR-10b fostered the phosphorylation of Smad3 and RF, while the inhibition of miR-10a and miR-10b resulted in a decrease in p-Smad3 levels and RF. Further research revealed that miR-10a and miR-10b, through binding to the 3'UTR region of Vasohibin-1 (VASH-1), suppressed the expression of VASH-1, thereby promoting the elevation of p-Smad3 and exacerbating the progression of RF. The miR-10 family may play a pivotal role in RF.

Sustained Effectiveness and Safety of Therapeutic miR-10a/b in Alleviating Diabetes and Gastrointestinal Dysmotility without Inducing Cancer or Inflammation in Murine Liver and Colon

microRNAs (miRNAs) are key regulators of both physiological and pathophysiological mechanisms in diabetes and gastrointestinal (GI) dysmotility. Our previous studies have demonstrated the therapeutic potential of miR-10a-5p mimic and miR-10b-5p mimic (miR-10a/b mimics) in rescuing diabetes and GI dysmotility in murine models of diabetes. In this study, we elucidated the safety profile of a long-term treatment with miR-10a/b mimics in diabetic mice. Male C57BL/6 mice were fed a high-fat, high-sucrose diet (HFHSD) to induce diabetes and treated by five subcutaneous injections of miR-10a/b mimics for a 5 month period. We examined the long-term effects of the miRNA mimics on diabetes and GI dysmotility, including an assessment of potential risks for cancer and inflammation in the liver and colon using biomarkers. HFHSD-induced diabetic mice subcutaneously injected with miR-10a/b mimics on a monthly basis for 5 consecutive months exhibited a marked reduction in fasting blood glucose levels with restoration of insulin and significant weight loss, improved glucose and insulin intolerance, and restored GI transit time. In addition, the miR-10a/b mimic-treated diabetic mice showed no indication of risk for cancer development or inflammation induction in the liver, colon, and blood for 5 months post-injections. This longitudinal study demonstrates that miR-10a/b mimics, when subcutaneously administered in diabetic mice, effectively alleviate diabetes and GI dysmotility for 5 months with no discernible risk for cancer or inflammation in the liver and colon. The sustained efficacy and favorable safety profiles position miR-10a/b mimics as promising candidates in miRNA-based therapeutics for diabetes and GI dysmotility.

Acetyl-CoA synthetase 2 promotes diabetic renal tubular injury in mice by rewiring fatty acid metabolism through SIRT1/ChREBP pathway

Diabetic nephropathy (DN) is characterized by chronic low-grade renal inflammatory responses, which greatly contribute to disease progression. Abnormal glucose metabolism disrupts renal lipid metabolism, leading to lipid accumulation, nephrotoxicity, and subsequent aseptic renal interstitial inflammation. In this study, we investigated the mechanisms underlying the renal inflammation in diabetes, driven by glucose-lipid metabolic rearrangement with a focus on the role of acetyl-CoA synthetase 2 (ACSS2) in lipid accumulation and renal tubular injury. Diabetic models were established in mice by the injection of streptozotocin and in human renal tubular epithelial HK-2 cells cultured under a high glucose (HG, 30 mmol/L) condition. We showed that the expression levels of ACSS2 were significantly increased in renal tubular epithelial cells (RTECs) from the diabetic mice and human diabetic kidney biopsy samples, and ACSS2 was co-localized with the pro-inflammatory cytokine IL-1β in RTECs. Diabetic ACSS2-deficient mice exhibited reduced renal tubular injury and inflammatory responses. Similarly, ACSS2 knockdown or inhibition of ACSS2 by ACSS2i (10 µmol/L) in HK-2 cells significantly ameliorated HG-induced inflammation, mitochondrial stress, and fatty acid synthesis. Molecular docking revealed that ACSS2 interacted with Sirtuin 1 (SIRT1). In HG-treated HK-2 cells, we demonstrated that ACSS2 suppressed SIRT1 expression and activated fatty acid synthesis by modulating SIRT1-carbohydrate responsive element binding protein (ChREBP) activity, leading to mitochondrial oxidative stress and inflammation. We conclude that ACSS2 promotes mitochondrial oxidative stress and renal tubular inflammation in DN by regulating the SIRT1-ChREBP pathway. This highlights the potential therapeutic value of pharmacological inhibition of ACSS2 for alleviating renal inflammation and dysregulation of fatty acid metabolic homeostasis in DN. Metabolic inflammation in the renal region, driven by lipid metabolism disorder, is a key factor in renal injury in diabetic nephropathy (DN). Acetyl-CoA synthetase 2 (ACSS2) is abundantly expressed in renal tubular epithelial cells (RTECs) and highly upregulated in diabetic kidneys. Deleting ACSS2 reduces renal fatty acid accumulation and markers of renal tubular injury in diabetic mice. We demonstrate that ACSS2 deletion inhibits ChREBP-mediated fatty acid lipogenesis, mitochondrial oxidative stress, and inflammatory response in RTECs, which play a major role in the progression of diabetic renal tubular injury in the kidney. These findings support the potential use of ACSS2 inhibitors in treating patients with DN.

Natural products in traditional Chinese medicine: molecular mechanisms and therapeutic targets of renal fibrosis and state-of-the-art drug delivery systems

Renal fibrosis (RF) is the end stage of several chronic kidney diseases. Its series of changes include excessive accumulation of extracellular matrix, epithelial-mesenchymal transition (EMT) of renal tubular cells, fibroblast activation, immune cell infiltration, and renal cell apoptosis. RF can eventually lead to renal dysfunction or even renal failure. A large body of evidence suggests that natural products in traditional Chinese medicine (TCM) have great potential for treating RF. In this article, we first describe the recent advances in RF treatment by several natural products and clarify their mechanisms of action. They can ameliorate the RF disease phenotype, which includes apoptosis, endoplasmic reticulum stress, and EMT, by affecting relevant signaling pathways and molecular targets, thereby delaying or reversing fibrosis. We also present the roles of nanodrug delivery systems, which have been explored to address the drawback of low oral bioavailability of natural products. This may provide new ideas for using natural products for RF treatment. Finally, we provide new insights into the clinical prospects of herbal natural products.

[The Role of TGF-β1/SMAD in Diabetic Nephropathy: Mechanisms and Research Development]

Diabetic nephropathy (DN) is a common complication of diabetes and a leading cause of end-stage renal disease. Transforming growth factor-β1 (TGF-β1)/SMAD signaling activation plays an important role in the onset and progression of DN. Reported findings suggest that the activation of TGF-β1 (including the latent form, the active form, and the receptors) and its downstream signaling proteins (SMAD3, SMAD7, etc.) plays a critical role in DN. In addition, TGF-β1/SMAD signaling may mediate the pathogenesis and progression of DN via various microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Emerging evidence shows that TGF-β1, SMAD3, and SMAD7 are the main signaling proteins that contribute to the development of DN, and that they can be potential targets for the treatment of DN. However, recent clinical trials have shown that the anti-TGF-β1 monoclonal antibody treatment fails to effectively alleviate DN, which suggests that upstream inhibition of TGF-β1/SMAD signaling does not alleviate clinical symptoms and that this may be related to the fact that TGF-β1/SMAD has multiple biological effects. Targeted inhibition of the downstream TGF-β1 signaling (e.g., SMAD3 and SMAD7) may be an effective approach to attenuate DN. This article discussed the current understanding of the molecular mechanisms and potential targets for the treatment and prevention of DN by focusing on TGF-β1/SMAD signaling.

Comprehensive analysis of the relationship between xanthine oxidoreductase activity and chronic kidney disease

Chronic kidney disease (CKD) is a common disease that seriously endangers human health. However, the potential relationship between xanthine oxidoreductase (XOR) activity and CKD remains unclear. In this study, we used clinical data, CKD datasets from the Gene Expression Omnibus database, and untargeted metabolomics to explain the relationship between XOR activity and CKD. First, XOR activity showed high correlation with the biomarkers of CKD, such as serum creatinine, blood urea nitrogen, uric acid, and estimated glomerular filtration rate. Then, we used least absolute shrinkage and selection operator logical regression algorithm and random forest algorithm to screen CKD molecular markers from differentially expressed genes, and the results of qRT-PCR of XDH, KOX-1, and ROMO1 were in accordance with the results of bioinformatics analyses. In addition, untargeted metabolomics analysis revealed that the purine metabolism pathway was significantly enriched in CKD patients in the simulated models of kidney fibrosis.

Flavin containing monooxygenase 2 regulates renal tubular cell fibrosis and paracrine secretion via SMURF2 in AKI‑CKD transformation

In the follow‑up of hospitalized patients with acute kidney injury (AKI), it has been observed that 15‑30% of these patients progress to develop chronic kidney disease (CKD). Impaired adaptive repair of the kidneys following AKI is a fundamental pathophysiological mechanism underlying renal fibrosis and the progression to CKD. Deficient repair of proximal tubular epithelial cells is a key factor in the progression from AKI to CKD. However, the molecular mechanisms involved in the regulation of fibrotic factor paracrine secretion by injured tubular cells remain incompletely understood. Transcriptome analysis and an ischemia‑reperfusion injury (IRI) model were used to identify the contribution of flavin‑containing monooxygenase 2 (FMO2) in AKI‑CKD. Lentivirus‑mediated overexpression of FMO2 was performed in mice. Functional experiments were conducted using TGF‑β‑induced tubular cell fibrogenesis and paracrine pro‑fibrotic factor secretion. Expression of FMO2 attenuated kidney injury induced by renal IRI, renal fibrosis, and immune cell infiltration into the kidneys. Overexpression of FMO2 not only effectively blocked TGF secretion in tubular cell fibrogenesis but also inhibited aberrant paracrine activation of pro‑fibrotic factors present in fibroblasts. FMO2 negatively regulated TGF‑β‑mediated SMAD2/3 activation by promoting the expression of SMAD ubiquitination regulatory factor 2 (SMURF2) and its nuclear translocation. During the transition from AKI to CKD, FMO2 modulated tubular cell fibrogenesis and paracrine secretion through SMURF2, thereby affecting the outcome of the disease.

Protective effect of GLP-1 analog liraglutide on podocytes in mice with diabetic nephropathy

Protection of podocytes is one of the important means to delay the progression of diabetic nephropathy (DN), and glucagon-like peptide-1 (GLP-1) has been shown to have a protective effect on the kidney in DN models, but whether it has a protective effect on podocytes and the potential mechanisms of action remain largely unknown. In the present study, we established a type 2 diabetes mellitus (T2DM) mouse model by high-fat diet feeding combined with streptozotocin (STZ) induction and administered the intervention for 14 weeks. We found that liraglutide significantly ameliorated podocyte injury in DN mice. Mechanistically, we detected glucagon-like peptide-1 receptor (GLP-1R) protein expression levels in kidney tissues by immunohistochemical staining, immunofluorescence staining, and western blotting and found that podocytes could express GLP-1R and liraglutide treatment could restore GLP-1R expression in the kidney tissues of DN mice. Furthermore, we found that NLRP3-induced inflammation and pyroptosis were positively correlated with podocyte injury in DN mice, and liraglutide inhibited the expression of NLRP3-induced inflammation and pyroptosis-related proteins. Our results suggest that liraglutide protects DN mouse podocytes by regulating GLP-1R in renal tissues and by regulating NLRP3-induced inflammation and pyroptosis.

MiR-132-3p activation aggravates renal ischemia-reperfusion injury by targeting Sirt1/PGC1alpha axis

The pathogenesis of renal ischemic diseases remains unclear. In this study, we demonstrate the induction of microRNA-132-3p (miR-132-3p) in ischemic acute kidney injury (AKI) and cultured renal tubular cells under oxidative stress. miR-132-3p mimic increased apoptosis in renal tubular cells and enhanced ischemic AKI in mice, whereas miR-132-3p inhibition offered protective effects. We analyzed miR-132-3p target genes through bioinformatic analysis and Sirt1 was predicted as the target gene of miR-132-3p. Luciferase microRNA target reporter assay further verified Sirt1 as a direct target of miR-132-3p. In cultured tubular cells and mouse kidneys, IRI and H2O2 treatment repressed Sirt1 and PGC-1α/NRF2/HO-1 expression, whereas anti-miR-132-3p preserved Sirt1 and PGC-1α/NRF2/HO-1 expression. In renal tubular, Sirt1 inhibitor suppressed PGC1-1α/NRF2/HO-1 expression and aggravated tubular apoptosis. Together, the results suggest that miR-132-3p induction aggravates ischemic AKI and oxidative stress by repressing Sirt1 expression, and miR-132-3p inhibition offers renal protection and may be a potential therapeutic target.

Loganin reduces diabetic kidney injury by inhibiting the activation of NLRP3 inflammasome-mediated pyroptosis

Diabetic kidney disease (DKD) is an essential cause of end-stage renal disease. The ongoing inflammatory response in the proximal tubule promotes the progression of DKD. Timely and effective blockade of the inflammatory process to protect the kidney during DKD progression is a proven strategy. The purpose of this study was to investigate the protective effect of loganin on diabetic nephropathy in vivo and in vitro and whether this effect was related to the inhibition of pyroptosis. The results indicated that loganin reduced fasting blood glucose, blood urea nitrogen and serum creatinine concentrations, and alleviated renal pathological changes in DKD mice. In parallel, loganin downregulated the expression of pyroptosis related proteins in the renal tubules of DKD mice and decreased serum levels of interleukin-1beta (IL-1β) and interleukin-18 (IL-18). Furthermore, in vitro experiments showed that loganin attenuated high glucose-induced HK-2 cell injury by reducing the expression of pyroptosis-related proteins, and cytokine levels were also decreased. These fundings were also confirmed in the polyphyllin VI (PPVI) -induced HK-2 cell pyroptosis model. Loganin reduces high glucose induced HK-2 cells pyroptosis by inhibiting reactive oxygen species (ROS) production and NOD-like receptor protein 3 (NLRP3) inflammasome activation. In conclusion, the inhibition of pyroptosis via inhibition of the NLRP3/Caspase-1/Gasdermin D (GSDMD) pathway might be an essential mechanism for loganin treatment of DKD.

miR-147 Represses NDUFA4, Inducing Mitochondrial Dysfunction and Tubular Damage in Cold Storage Kidney Transplantation

SIGNIFICANCE STATEMENT

Cold storage-associated transplantation (CST) injury occurs in renal transplant from deceased donors, the main organ source. The pathogenesis of CST injury remains poorly understood, and effective therapies are not available. This study has demonstrated an important role of microRNAs in CST injury and revealed the changes in microRNA expression profiles. Specifically, microRNA-147 (miR-147) is consistently elevated during CST injury in mice and in dysfunctional renal grafts in humans. Mechanistically, NDUFA4 (a key component of mitochondrial respiration complex) is identified as a direct target of miR-147. By repressing NDUFA4, miR-147 induces mitochondrial damage and renal tubular cell death. Blockade of miR-147 and overexpression of NDUFA4 reduce CST injury and improve graft function, unveiling miR-147 and NDUFA4 as new therapeutic targets in kidney transplantation.

BACKGROUND

Kidney injury due to cold storage-associated transplantation (CST) is a major factor determining the outcome of renal transplant, for which the role and regulation of microRNAs remain largely unclear.

METHODS

The kidneys of proximal tubule Dicer (an enzyme for microRNA biogenesis) knockout mice and their wild-type littermates were subjected to CST to determine the function of microRNAs. Small RNA sequencing then profiled microRNA expression in mouse kidneys after CST. Anti-microRNA-147 (miR-147) and miR-147 mimic were used to examine the role of miR-147 in CST injury in mouse and renal tubular cell models.

RESULTS

Knockout of Dicer from proximal tubules attenuated CST kidney injury in mice. RNA sequencing identified multiple microRNAs with differential expression in CST kidneys, among which miR-147 was induced consistently in mouse kidney transplants and in dysfunctional human kidney grafts. Anti-miR-147 protected against CST injury in mice and ameliorated mitochondrial dysfunction after ATP depletion injury in renal tubular cells in intro . Mechanistically, miR-147 was shown to target NDUFA4, a key component of the mitochondrial respiration complex. Silencing NDUFA4 aggravated renal tubular cell death, whereas overexpression of NDUFA4 prevented miR-147-induced cell death and mitochondrial dysfunction. Moreover, overexpression of NDUFA4 alleviated CST injury in mice.

CONCLUSIONS

microRNAs, as a class of molecules, are pathogenic in CST injury and graft dysfunction. Specifically, miR-147 induced during CST represses NDUFA4, leading to mitochondrial damage and renal tubular cell death. These results unveil miR-147 and NDUFA4 as new therapeutic targets in kidney transplantation.

Insights into the Role of Plasmatic and Exosomal microRNAs in Oxidative Stress-Related Metabolic Diseases

A common denominator of metabolic diseases, including type 2 diabetes Mellitus, dyslipidemia, and atherosclerosis, are elevated oxidative stress and chronic inflammation. These complex, multi-factorial diseases are caused by the detrimental interaction between the individual genetic background and multiple environmental stimuli. The cells, including the endothelial ones, acquire a preactivated phenotype and metabolic memory, exhibiting increased oxidative stress, inflammatory gene expression, endothelial vascular activation, and prothrombotic events, leading to vascular complications. There are different pathways involved in the pathogenesis of metabolic diseases, and increased knowledge suggests a role of the activation of the NF-kB pathway and NLRP3 inflammasome as key mediators of metabolic inflammation. Epigenetic-wide associated studies provide new insight into the role of microRNAs in the phenomenon of metabolic memory and the development consequences of vessel damage. In this review, we will focus on the microRNAs related to the control of anti-oxidative enzymes, as well as microRNAs related to the control of mitochondrial functions and inflammation. The objective is the search for new therapeutic targets to improve the functioning of mitochondria and reduce oxidative stress and inflammation, despite the acquired metabolic memory.

STING deletion alleviates podocyte injury through suppressing inflammation by targeting NLRP3 in diabetic kidney disease

An increasing number of studies have shown that immune inflammatory response plays a vital role in diabetic kidney disease (DKD). Nod-like receptor protein 3 (NLRP3) inflammasome-dependent inflammatory response is a key mechanism in the initiation and development of DKD. The stimulator of interferon genes (STING) is an adaptor protein that can drive noninfectious inflammation and pyroptosis. However, the mechanism of STING regulating immune inflammation and the interaction with NLRP3-dependent pyroptosis in high glucose state still remains unclear. This study evaluated the potential role of STING in high glucose (HG)-induced podocyte inflammation response. STING expression was significantly increased in db/db mice, STZ-treated diabetic mice, and HG-treated podocytes. Podocyte-specific deletion of STING alleviated podocyte injury, renal dysfunction, and inflammation in STZ-induced diabetic mice. STING inhibitor (H151) administration ameliorated inflammation and improved renal function in db/db mice. STING deletion in podocytes attenuated the activation of the NLRP3 inflammasome and podocyte pyroptosis in STZ-induced diabetic mice. In vitro, modulated STING expression by STING siRNA alleviated pyroptosis and NLRP3 inflammasome activation in HG-treated podocytes. NLRP3 over-expression offset the beneficial effects of STING deletion. These results indicate that STING deletion suppresses podocyte inflammation response through suppressing NLRP3 inflammasome activation and provide evidence that STING may be a potential target for podocyte injury in DKD.

miR-10a-3p modulates adiposity and suppresses adipose inflammation through TGF-β1/Smad3 signaling pathway

Background

Obesity is a multifactorial disease characterized by an enhanced amount of fat and energy storage in adipose tissue (AT). Obesity appears to promote and maintain low-grade chronic inflammation by activating a subset of inflammatory T cells, macrophages, and other immune cells that infiltrate the AT. Maintenance of AT inflammation during obesity involves regulation by microRNAs (miRs), which also regulate the expression of genes implicated in adipocyte differentiation. This study aims to use ex vivo and in vitro approaches to evaluate the role and mechanism of miR-10a-3p in adipose inflammation and adipogenesis.

Methods

Wild-type BL/6 mice were placed on normal (ND) and high-fat diet (HFD) for 12 weeks and their obesity phenotype, inflammatory genes, and miRs expression were examined in the AT. We also used differentiated 3T3-L1 adipocytes for mechanistic in vitro studies.

Results

Microarray analysis allowed us to identify an altered set of miRs in the AT immune cells and Ingenuity pathway analysis (IPA) prediction demonstrated that miR-10a-3p expression was downregulated in AT immune cells in the HFD group as compared to ND. A molecular mimic of miR-10a-3p reduced expression of inflammatory M1 macrophages, cytokines, and chemokines, including transforming growth factor-beta 1 (TGF-β1), transcription factor Krüppel-like factor 4 (KLF4), and interleukin 17F (IL-17F) and induced expression of forkhead box P3 (FoxP3) in the immune cells isolated from AT of HFD-fed mice as compared to ND. In differentiated 3T3-L1 adipocytes, the miR-10a-3p mimics also reduced expression of proinflammatory genes and lipid accumulation, which plays a role in the dysregulation of AT function. In these cells, overexpression of miR-10a-3p reduced the expression of TGF-β1, Smad3, CHOP-10, and fatty acid synthase (FASN), relative to the control scramble miRs.

Conclusion

Our findings suggest that miR-10a-3p mimic mediates the TGF-β1/Smad3 signaling to improve metabolic markers and adipose inflammation. This study provides a new opportunity for the development of miR-10a-3p as a novel therapeutic for adipose inflammation, and its associated metabolic disorders.

Cardiovascular complications of diabetes: role of non-coding RNAs in the crosstalk between immune and cardiovascular systems

Diabetes mellitus, a group of metabolic disorders characterized by high levels of blood glucose caused by insulin defect or impairment, is a major risk factor for cardiovascular diseases and related mortality. Patients with diabetes experience a state of chronic or intermittent hyperglycemia resulting in damage to the vasculature, leading to micro- and macro-vascular diseases. These conditions are associated with low-grade chronic inflammation and accelerated atherosclerosis. Several classes of leukocytes have been implicated in diabetic cardiovascular impairment. Although the molecular pathways through which diabetes elicits an inflammatory response have attracted significant attention, how they contribute to altering cardiovascular homeostasis is still incompletely understood. In this respect, non-coding RNAs (ncRNAs) are a still largely under-investigated class of transcripts that may play a fundamental role. This review article gathers the current knowledge on the function of ncRNAs in the crosstalk between immune and cardiovascular cells in the context of diabetic complications, highlighting the influence of biological sex in such mechanisms and exploring the potential role of ncRNAs as biomarkers and targets for treatments. The discussion closes by offering an overview of the ncRNAs involved in the increased cardiovascular risk suffered by patients with diabetes facing Sars-CoV-2 infection.

Natural products in attenuating renal inflammation via inhibiting the NLRP3 inflammasome in diabetic kidney disease

Diabetic kidney disease (DKD) is a prevalent and severe complications of diabetes and serves as the primary cause of end-stage kidney disease (ESKD) globally. Increasing evidence indicates that renal inflammation is critical in the pathogenesis of DKD. The nucleotide - binding oligomerization domain (NOD) - like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most extensively researched inflammasome complex and is considered a crucial regulator in the pathogenesis of DKD. The activation of NLRP3 inflammasome is regulated by various signaling pathways, including NF- κB, thioredoxin-interacting protein (TXNIP), and non-coding RNAs (ncRNA), among others. Natural products are chemicals extracted from living organisms in nature, and they typically possess pharmacological and biological activities. They are invaluable sources for drug design and development. Research has demonstrated that many natural products can alleviate DKD by targeting the NLRP3 inflammasome. In this review, we highlight the role of the NLRP3 inflammasome in DKD, and the pathways by which natural products fight against DKD via inhibiting the NLRP3 inflammasome activation, so as to provide novel insights for the treatment of DKD.

PIM1 attenuates renal ischemia-reperfusion injury by inhibiting ASK1-JNK/P38

Renal ischemia-reperfusion injury (IRI) is the main cause of acute kidney injury (AKI), yet therapeutic approaches to alleviate IRI remain limited. PIM1 (provirus integration site for Moloney murine leukemia virus 1) is a constitutive serine threonine kinase that phosphorylates various substrates to regulate cell death and survival. However, the role of PIM1 in renal IRI remains unclear. This study aims to investigate the effect of PIM1 on renal IRI and explore its downstream regulatory mechanism. In this study, we inhibited or overexpressed PIM1 in mice and cultured proximal tubular cells, and then induced renal IRI model in vivo and hypoxia reoxygenation (HR) model in vitro. Renal function, renal structure injuries and cellular death were assessed to reflect the extent of IRI. The expression of PIM1 and the levels of ASK1, MAPK and their phosphorylated forms were detected by immunoblot. RNA sequencing of kidney cortex was performed to analyze downstream pathway of PIM1 in renal IRI. The results showed that PIM1 expression was significantly upregulated in renal IRI mouse model and in renal tubular cell HR model. AZD1208 (a PIM1 inhibitor) aggravated renal IRI, while PIM1 overexpression ameliorated renal IRI. This was involved in the regulation of the ASK1-MAPK pathway. Moreover, results demonstrated that ASK1 was a downstream target of PIM1 by administering Selonsertib (an inhibitor of ASK1 activity), and inhibiting ASK1 alleviated cell death after HR in PIM1 knockdown cells by reducing JNK/P38 activation. In conclusion, this study elucidated the protective effect of PIM1 on renal IRI, and the underlying mechanism may be related to ASK1-JNK/P38 signaling pathway. Taken together, PIM1 may be a potential therapeutic target for renal IRI.

MiR-20a-5p alleviates kidney ischemia/reperfusion injury by targeting ACSL4-dependent ferroptosis

Ischemia/reperfusion injury (IRI) is prone to occur after kidney transplantation, leading to delayed graft function (DGF). MicroRNAs play a crucial role in the pathogenesis of ischemia/reperfusion-induced acute kidney injury, and miR-20a-5p was found to be the most significantly upregulated gene in a DGF patient cohort. However, the roles of microRNAs in transplanted kidneys remain largely unknown. In this study, we found that miR-20a-5p was upregulated in the kidneys of acute kidney injury mice and in patients with DGF. We identified early growth response-1 as a critical upstream target and verified the binding of early growth response-1 to a predicted sequence in the promoter region of the miR-20a-5p gene. Functionally, the miR-20a-5p mimic attenuated IRI and postischemic renal fibrosis, whereas the miR-20a-5p inhibitor delivery aggravated IRI and fibrosis. Importantly, delivery of the miR-20a-5p mimic or inhibitor in the donor kidneys attenuated or aggravated renal loss and structural damage in cold storage transplantation injury. Furthermore, our study identified miR-20a-5p as a negative regulator of acyl-CoA synthetase long-chain family member 4 (ACSL4) by targeting the 3' untranslated region of ACSL4 mRNA, thereby inhibiting ACSL4-dependent ferroptosis. Our results suggest a potential therapeutic application of miR-20a-5p in kidney transplantation through the inhibition of ACSL4-dependent ferroptosis.

Epigenetics and endoplasmic reticulum in podocytopathy during diabetic nephropathy progression

Proteinuria or nephrotic syndrome are symptoms of podocytopathies, kidney diseases caused by direct or indirect podocyte damage. Human health worldwide is threatened by diabetic nephropathy (DN), the leading cause of end-stage renal disease (ESRD) in the world. DN development and progression are largely dependent on inflammation. The effects of podocyte damage on metabolic disease and inflammatory disorders have been documented. Epigenetic and endoplasmic reticulum (ER) stress are also evident in DN. Targeting inflammation pathway and ER stress in podocytes may be a prospective therapy to prevent the progression of DN. Here, we review the mechanism of epigenetics and ER stress on podocyte inflammation and apoptosis, and discuss the potential amelioration of podocytopathies by regulating epigenetics and ER stress as well as by targeting inflammatory signaling, which provides a theoretical basis for drug development to ameliorate DN.

MicroRNA-10 Family Promotes the Epithelial-to-Mesenchymal Transition in Renal Fibrosis by the PTEN/Akt Pathway

Renal fibrosis (RF) is a common reason for renal failure, and epithelial-mesenchymal transition (EMT) is a vital mechanism that promotes the development of RF. It is known that microRNA-10 (miR-10) plays an important role in cancer EMT; however, whether it takes part in the EMT process of RF remains unclear. Therefore, we established an in vivo model of unilateral ureteral obstruction (UUO), and an in vitro model using TGF-β1, to investigate whether and how miR-10a and miR-10b take part in the EMT of RF. In addition, the combinatorial effects of miR-10a and miR-10b were assessed. We discovered that miR-10a and miR-10b are overexpressed in UUO mice, and miR-10a, miR-10b, and miRs-10a/10b knockout attenuated RF and EMT in UUO-treated mouse kidneys. Moreover, miR-10a and miR-10b overexpression combinatorially promoted RF and EMT in TGF-β1-treated HK-2 cells. Inhibiting miR-10a and miR-10b attenuated RF and EMT induced by TGF-β1. Mechanistically, miR-10a and miR-10b suppressed PTEN expression by binding to its mRNA3'-UTR and promoting the Akt pathway. Moreover, PTEN overexpression reduced miR-10a and miR-10b effects on Akt phosphorylation (p-Akt), RF, and EMT in HK-2 cells treated with TGF-β1. Taken together, miR-10a and miR-10b act combinatorially to negatively regulate PTEN, thereby activating the Akt pathway and promoting the EMT process, which exacerbates RF progression.

USP25 UPREGULATION BOOSTS GSDMD -MEDIATED PYROPTOSIS OF ACINAR CELLS IN ACUTE PANCREATITIS

ABSTRACT

Acute pancreatitis (AP) is an inflammation-associated disorder in the digestive system. Ubiquitin-specific peptidase 25 ( USP25 ) can modulate inflammation in diseases. This study expounded on the role of USP25 in pyroptosis of acinar cells in AP. Acinar cells were treated with lipopolysaccharide (LPS) and caerulein (CRE) to induce AP. Afterward, the expression patterns of USP25 , microRNA (miR)-10a-5p, and Krüppel-like factor 4 ( KLF4 ) in acinar cells were examined. Then, acinar cell viability and levels of NLR family pyrin-domain containing 3 (NLRP3), cleaved caspase-1, cleaved N -terminal gasdermin D ( GSDMD - N ), interleukin (IL)-1β, and IL-18 were determined. We observed that USP25 was highly expressed in AP models, and silencing USP25 increased cell viability and inhibited pyroptosis of AP acinar cells. The bindings of USP25 to KLF4 and miR-10a-5p to KLF4 and the GSDMD 3'UTR sequence were validated. We found that USP25 binding to KLF4 inhibited ubiquitination degradation of KLF4 , KLF4 transcriptionally decreased miR-10a-5p expression, and miR-10a-5p targeted GSDMD expression. Finally, rescue experiments proved that KLF4 overexpression or miR-10a-5p suppression enhanced pyroptosis of AP acinar cells. Overall, USP25 stabilized KLF4 expression through deubiquitination, limited miR-10a-5p expression, and increased GSDMD expression, finally promoting pyroptosis of acinar cells in AP.

NLRP3-mediated pyroptosis in diabetic nephropathy

Diabetic nephropathy (DN) is the main cause of end-stage renal disease (ESRD), which is characterized by a series of abnormal changes such as glomerulosclerosis, podocyte loss, renal tubular atrophy and excessive deposition of extracellular matrix. Simultaneously, the occurrence of inflammatory reaction can promote the aggravation of DN-induced kidney injury. The most important processes in the canonical inflammasome pathway are inflammasome activation and membrane pore formation mediated by gasdermin family. Converging studies shows that pyroptosis can occur in renal intrinsic cells and participate in the development of DN, and its activation mechanism involves a variety of signaling pathways. Meanwhile, the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome can not only lead to the occurrence of inflammatory response, but also induce pyroptosis. In addition, a number of drugs targeting pyroptosis-associated proteins have been shown to have potential for treating DN. Consequently, the pathogenesis of pyroptosis and several possible activation pathways of NLRP3 inflammasome were reviewed, and the potential drugs used to treat pyroptosis in DN were summarized in this review. Although relevant studies are still not thorough and comprehensive, these findings still have certain reference value for the understanding, treatment and prognosis of DN.

The fibrogenic niche in kidney fibrosis: components and mechanisms

Kidney fibrosis, characterized by excessive deposition of extracellular matrix (ECM) that leads to tissue scarring, is the final common outcome of a wide variety of chronic kidney diseases. Rather than being distributed uniformly across the kidney parenchyma, renal fibrotic lesions initiate at certain focal sites in which the fibrogenic niche is formed in a spatially confined fashion. This niche provides a unique tissue microenvironment that is orchestrated by a specialized ECM network consisting of de novo-induced matricellular proteins. Other structural elements of the fibrogenic niche include kidney resident and infiltrated inflammatory cells, extracellular vesicles, soluble factors and metabolites. ECM proteins in the fibrogenic niche recruit soluble factors including WNTs and transforming growth factor-β from the extracellular milieu, creating a distinctive profibrotic microenvironment. Studies using decellularized ECM scaffolds from fibrotic kidneys show that the fibrogenic niche autonomously promotes fibroblast proliferation, tubular injury, macrophage activation and endothelial cell depletion, pathological features that recapitulate key events in the pathogenesis of chronic kidney disease. The concept of the fibrogenic niche represents a paradigm shift in understanding of the mechanism of kidney fibrosis that could lead to the development of non-invasive biomarkers and novel therapies not only for chronic kidney disease, but also for fibrotic diseases of other organs.

RP105 protects against ischemic and septic acute kidney injury via suppressing TLR4/NF-κB signaling pathways

Acute kidney injury (AKI) is a critical and severe clinical disease caused by a variety of factors. Toll-like receptors (TLRs) play a crucial role in pathogenesis of AKI. Radioprotective 105 kDa protein (RP105) is a member of the TLR family, but the role of RP105 in AKI is unknown. In this study, we overexpressed RP105 in renal tissue and cultured proximal tubular cells in which we then induced ischemic and septic AKI. Renal structure injuries were examined by hematoxylin eosin staining, while renal function was assessed by measuring serum blood urea nitrogen (BUN) and creatinine (SCr) levels. The TUNEL assay was used to detect apoptosis induced changes in the expression of RP105, and nuclear factor κB (NF-κB) in renal tissue detected by Western blot. Inflammatory cytokines including iNOS, IL-1β, IL-6, and TNF-α were detected by quantitative real-time PCR. The inflammatory indicators, F4/80 and MPO, were identified by IHC staining. The results showed that expression of the TLR4/NF-kB signaling pathway was enhanced in renal ischemia-reperfusion injury and septic renal injury, and that overexpression of RP105 in renal tissue alleviated ischemic and septic AKI. Moreover, RP105 gene delivery was associated with reduced renal inflammatory cells infiltration and inflammatory cytokines after AKI. RP105 overexpression also inhibited nuclear translocation of NF-κB after AKI in both in vitro and in vivo, and blunted the interaction between Myeloid Differentiation factor 2 (MD2) and TLR4. These results indicated that RP105 protected against renal ischemic and septic AKI injury by suppressing inflammatory responses mediated by TLR4 signaling pathways. This study suggests that the anti-inflammatory roles of RP105 have potential for preventing and treating renal ischemic and septic AKI.

Polystyrene microplastics induced oxidative stress, inflammation and necroptosis via NF-κB and RIP1/RIP3/MLKL pathway in chicken kidney

Microplastics (MPs) are a novel environment pollutant widespread among the natural environment, also causing damage to aquatic animals and mammals. However, their effects on the kidney of poultry are still unclear. In this study, chickens were exposure to the different doses of PS-MPs (1, 10, 100 mg/L) for six weeks, with 1 mg/L being the environmental concentration. The effects of PS-MPs on renal tissue damage in chicken were analyzed. Our results suggested that MPs exposure causes mitochondrial morphology and dysbiosis (MFN1/2, OPA1, Drp1), mitochondrial structural damage by triggering imbalance in mitochondrial dynamics. Antioxidant enzyme (SOD, CAT, MDA, GSH, T-AOC) activity was significantly altered, which in turn caused oxidative stress. H&E staining results showed damage and inflammation of chicken kidney. Mechanistically, the inflammation featured by activated NF-κB P65 and increased expression of pro-inflammatory factors (TNFα, iNOs, IL-1β and IL-6). Moreover, PS-MPs intake induced necroptosis through activated RIP1/RIP3/MLKL signaling pathway. In conclusion, our study was the first to show that oral intake of PS-MPs induced inflammation and necroptosis in chicken kidney and the differences in damage were linked to the concentration of PS-MPs. The purpose of this study provided theoretical support for the environmental risk assessment of PS-MPs.

A Glimpse of Inflammation and Anti-Inflammation Therapy in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a common complication of diabetes mellitus and a major cause of end-stage kidney disease (ESKD). The pathogenesis of DKD is very complex and not completely understood. Recently, accumulated evidence from in vitro and in vivo studies has demonstrated that inflammation plays an important role in the pathogenesis and the development of DKD. It has been well known that a variety of pro-inflammatory cytokines and related signaling pathways are involved in the procession of DKD. Additionally, some anti-hyperglycemic agents and mineralocorticoid receptor antagonists (MRAs) that are effective in alleviating the progression of DKD have anti-inflammatory properties, which might have beneficial effects on delaying the progression of DKD. However, there is currently a lack of systematic overviews. In this review, we focus on the novel pro-inflammatory signaling pathways in the development of DKD, including the nuclear factor kappa B (NF-κB) signaling pathway, toll-like receptors (TLRs) and myeloid differentiation primary response 88 (TLRs/MyD88) signaling pathway, adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling pathways, inflammasome activation, mitochondrial DNA (mtDNA) release as well as hypoxia-inducible factor-1(HIF-1) signaling pathway. We also discuss the related anti-inflammation mechanisms of metformin, finerenone, sodium-dependent glucose transporters 2 (SGLT2) inhibitors, Dipeptidyl peptidase-4 (DPP-4) inhibitors, Glucagon-like peptide-1 (GLP-1) receptor agonist and traditional Chinese medicines (TCM).

Pathogenic Role of MicroRNA Dysregulation in Podocytopathies

MicroRNAs (miRNAs) participate in the regulation of various important biological processes by regulating the expression of various genes at the post-transcriptional level. Podocytopathies are a series of renal diseases in which direct or indirect damage of podocytes results in proteinuria or nephrotic syndrome. Despite decades of research, the exact pathogenesis of podocytopathies remains incompletely understood and effective therapies are still lacking. An increasing body of evidence has revealed a critical role of miRNAs dysregulation in the onset and progression of podocytopathies. Moreover, several lines of research aimed at improving common podocytopathies diagnostic tools and avoiding invasive kidney biopsies have also identified circulating and urine miRNAs as possible diagnostic and prognostic biomarkers for podocytopathies. The present review mainly aims to provide an updated overview of the recent achievements in research on the potential applicability of miRNAs involved in renal disorders related to podocyte dysfunction by laying particular emphasis on focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), membranous nephropathy (MN), diabetic kidney disease (DKD) and IgA nephropathy (IgAN). Further investigation into these dysregulated miRNAs will not only generate novel insights into the mechanisms of podocytopathies, but also might yield novel strategies for the diagnosis and therapy of this disease.

The Role of the NLRP3 Inflammasome in Mediating Glomerular and Tubular Injury in Diabetic Nephropathy

The NOD-like receptor protein 3 (NLRP3) inflammasome is a multi-protein signalling complex integral to the chronic inflammatory response, activated in response to sterile and non-sterile cellular damage. The assembly and activation of the NLRP3 inflammasome comprise a two-step process involving nuclear factor kappa B (NFkB)-mediated priming, followed by canonical, non-canonical or alternative signalling pathways. These result in the maturation and release of inflammatory cytokines interleukin 1 beta (IL1ß) and interleukin-18 (IL18), which are associated with chronic inflammatory conditions including diabetic kidney disease. Diabetic nephropathy is a condition affecting ∼40% of people with diabetes, the key underlying pathology of which is tubulointerstitial inflammation and fibrosis. There is growing evidence to suggest the involvement of the NLRP3 inflammasome in this chronic inflammation. Early deterioration of kidney function begins in the glomerulus, with tubular inflammation dictating the progression of late-stage disease. Priming and activation of the NLRP3 inflammasome have been linked to several clinical markers of nephropathy including proteinuria and albuminuria, in addition to morphological changes including mesangial expansion. Treatment options for diabetic nephropathy are limited, and research that examines the impact of directly targeting the NLRP3 inflammasome, or associated downstream components are beginning to gain favour, with several agents currently in clinical trials. This review will explore a role for NLRP3 inflammasome activation and signalling in mediating inflammation in diabetic nephropathy, specifically in the glomerulus and proximal tubule, before briefly describing the current position of therapeutic research in this field.

Signaling pathways of chronic kidney diseases, implications for therapeutics

Chronic kidney disease (CKD) is a chronic renal dysfunction syndrome that is characterized by nephron loss, inflammation, myofibroblasts activation, and extracellular matrix (ECM) deposition. Lipotoxicity and oxidative stress are the driving force for the loss of nephron including tubules, glomerulus, and endothelium. NLRP3 inflammasome signaling, MAPK signaling, PI3K/Akt signaling, and RAAS signaling involves in lipotoxicity. The upregulated Nox expression and the decreased Nrf2 expression result in oxidative stress directly. The injured renal resident cells release proinflammatory cytokines and chemokines to recruit immune cells such as macrophages from bone marrow. NF-κB signaling, NLRP3 inflammasome signaling, JAK-STAT signaling, Toll-like receptor signaling, and cGAS-STING signaling are major signaling pathways that mediate inflammation in inflammatory cells including immune cells and injured renal resident cells. The inflammatory cells produce and secret a great number of profibrotic cytokines such as TGF-β1, Wnt ligands, and angiotensin II. TGF-β signaling, Wnt signaling, RAAS signaling, and Notch signaling evoke the activation of myofibroblasts and promote the generation of ECM. The potential therapies targeted to these signaling pathways are also introduced here. In this review, we update the key signaling pathways of lipotoxicity, oxidative stress, inflammation, and myofibroblasts activation in kidneys with chronic injury, and the targeted drugs based on the latest studies. Unifying these pathways and the targeted therapies will be instrumental to advance further basic and clinical investigation in CKD.

Circ_0004951 Promotes Pyroptosis of Renal Tubular Cells via the NLRP3 Inflammasome in Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) has become the leading cause of chronic kidney disease (CKD) in many countries. Recent studies have shown that circular RNA and pyroptosis play an important role in pathogenesis of DKD.

Methods

We analyzed expression patterns of circRNAs in human kidney biopsy tissues obtained from type 2 DKD (n = 9) and nephrectomy (n = 9) patients. Next, we cultured human renal tubular epithelial cells (HK2) in high glucose condition and detected circ_0004951, miR-93-5p, NLR Pyrin Domain Containing 3 (NLRP3) inflammasome-related indicators and pyroptosis. Furthermore, we performed Bioinformatics analysis and dual-luciferase reporter assay to analyze the relationship among circ_0004951, miR-93-5p and NLRP3.

Results

Circ_0004951 was significantly upregulated in kidney tissues from DKD patients and HK2 in high glucose condition vs. control. Knockdown of circ_0004951 mediated a significant suppression of HK2 pyroptosis, while results from bioinformatics analysis revealed that circ_0004951 has binding sites with miR-93-5p and miR-93-5p could bind to NLRP3. Results from dual-luciferase reporter assay further corroborated this finding. Finally, observations from rescue experiments showed that down-regulation of miR-93-5p and upregulation of NLRP3 markedly attenuated the anti-pyroptosis and anti-inflammatory effects of circ_0004951 knockdown on HK2.

Conclusion

Circ_0004951 promotes pyroptosis of renal tubular epithelial cells in DKD via the miR-93-5p/NLRP3 inflammasome pathway, suggesting its potential for clinical diagnosis and treatment of DKD.

MicroRNA-10a/b inhibit TGF-β/Smad-induced renal fibrosis by targeting TGF-β receptor 1 in diabetic kidney disease

TGF-β/Smad signaling plays a vital role in the development of fibrosis in diabetic kidney disease (DKD). However, remedies targeting key elements in TGF-β/Smad signaling are lacking. Here, we found that TGF-β receptor 1 (TGFBR1), a key protein in TGF-β/Smad signaling, was upregulated in kidney from diabetic mice and patients with DKD. Induction of TGFBR1 was regulated by microRNA-10a and -10b (miR-10a/b) by a post-transcriptional mechanism. Furthermore, the decreased XRN2, an exoribonuclease, was identified to contribute to affecting miR-10a/b maturation in vitro. In streptozotocin (STZ)-induced DKD mice, preventing the reduction of miR-10a/b in the kidney by an in situ lentivirus-injection method attenuated collagen deposition and foot process effacement, whereas deprivation of miR-10a/b aggravated renal fibrosis. Mechanistically, manipulating miR-10a/b in the kidney influenced TGFBR1 protein expression, TGF-β/Smad signaling activation, and downstream pro-fibrotic genes expression including fibronectin (FN) and α-smooth muscle actin (α-SMA). In a cohort of patients diagnosed DKD, renal miR-10a/b expressions were downregulated, whereas both TGFBR1 and fibrosis were enhanced. Our finding suggests that overexpressing miR-10a/b in kidney may be a promising method for the treatment of fibrosis in DKD.

Activation of the NLRP3 inflammasome by RAC1 mediates a new mechanism in diabetic nephropathy

OBJECTIVE

Inflammation is central to the development and progression of diabetic nephropathy (DN). Although the exact mechanisms of inflammation in the kidney have not been well elucidated, pyrin domain containing 3 (NLRP3) inflammasome activation is involved in the onset and progression of DN. Here, we investigated the underlying regulatory mechanisms of hyperglycaemia-induced NLRP3 inflammasome activation in the kidney.

METHODS

HEK293T cells received high glucose, and the cell proliferation and apoptosis were detected. Biochemical indicators in db/db mice were tested by kits, and the morphological changes in the kidney were observed using staining methods and transmission electron microscopy. The interaction of Ras-related C3 botulinum toxin substrate 1 (RAC1) and NLRP3 inflammasome in cells and in mice was assessed by co-immunoprecipitation (Co-IP) and immunofluorescence. Expression of all proteins was examined by western blotting and immunohistochemistry. In additional, the directly combination of RAC1 and NLRP3 was evaluated by GST Pulldown.

RESULTS

High-glucose and hyperglycaemia conditions resulted in Ras-related C3 botulinum toxin substrate 1 (RAC1) and NLRP3 inflammasome interactions in cells and in mice. Additionally, RAC1 promoted NLRP3 inflammasome activation and then induced cell damage, and morphological and functional abnormalities in the kidney. We also observed that RAC1 activates the NLRP3 inflammasome by directly binding to NLRP3.

CONCLUSION

In the present study, we confirmed that RAC1 binding to NLRP3 is sufficient to activate the NLRP3 inflammasome in the kidney and accelerate DN pathological processes. These results elucidate the upstream cellular and molecular mechanisms of NLRP3 inflammasome activation and provide new therapeutic strategies for the treatment of DN.