VEGF-B antibody and interleukin-22 fusion protein ameliorates diabetic nephropathy through inhibiting lipid accumulation and inflammatory responses

An update on IL-22 therapies in alcohol-associated liver disease and beyond

Excessive alcohol consumption drives the development of alcohol-associated liver disease (ALD), including steatohepatitis, cirrhosis, and hepatocellular carcinoma, and its associated complications, such as hepatorenal syndrome. Hepatocyte death, inflammation, and impaired liver regeneration are key processes implicated in the pathogenesis and progression of ALD. Despite extensive research, therapeutic options for ALD remain limited. Interleukin-22 (IL-22) has emerged as a promising therapeutic target due to its hepatoprotective properties mediated through the activation of signal transducer and activator of transcription 3 (STAT3) signaling pathway. IL-22 enhances hepatocyte survival by mitigating apoptosis, oxidative stress, and inflammation while simultaneously promoting liver regeneration through the proliferation of hepatocytes and hepatic progenitor cells and the upregulation of growth factors. Additionally, IL-22 exerts protective effects on epithelial cells in various organs affected by ALD and its associated complications. Studies from preclinical models and early-phase clinical trials of IL-22 agonists, such as F-652 and UTTR1147A, have shown favorable safety profiles, good tolerability, and encouraging efficacy in reducing liver injury and promoting regeneration. However, the heterogeneity and multifactorial nature of ALD present ongoing challenges. Further research is needed to optimize IL-22-based therapies and clarify their roles within a comprehensive approach to ALD management. This review summarizes the current understanding of IL-22 biology and its role in ALD pathophysiology and ALD-associated complications along with therapeutic application of IL-22, potential benefits and limitations.

Wogonoside ameliorates oxidative damage in tubular epithelial cells of diabetic nephropathy by modulating the HNF4A-NRF2 axis

Diabetic nephropathy (DN), a leading cause of end-stage renal disease, presents significant challenges due to its complex pathophysiology and limited effective treatment options. Increasing evidence suggests that tubular injury is an early event preceding glomerular damage in DN. Wogonoside, a natural flavonoid derived from Scutellaria baicalensis, has not been previously reported for DN treatment. This study aims to investigate the protective effects and underlying mechanisms of wogonoside on renal tubular epithelial cells (TECs) in DN. The results showed that wogonoside mitigates high glucose (HG)-induced oxidative stress in TCMK-1 cells. Additionally, wogonoside protects renal function, reduces renal tubular damage, and modulates the oxidative stress response in HFD/STZ-induced DN mouse model. Importantly, our results indicated that hepatocyte nuclear factor 4 alpha (HNF4A) expression is downregulated in the kidneys of DN mice and HG-induced TCMK-1 cells. Wogonoside can bind to HNF4A, upregulate its expression, and promote nuclear translocation. Bioinformatic analysis suggested that NRF2 might be a downstream signaling of HNF4A. This was confirmed by Co-IP and experiments involving HNF4A overexpression and NRF2 knockdown, which demonstrated that wogonoside regulates the HNF4A-NRF2 axis to alleviate oxidative stress in TECs. Collectively, these findings identify wogonoside as a possible therapeutic agent for DN, highlighting HNF4A as a promising target for intervention.

Yishen Tongluo formula ameliorates kidney injury modulating inflammation and apoptosis in streptozotocin-induced diabetic kidney disease mice

OBJECTIVE

To investigate the effect and mechanism of Yishen Tongluo formula (, YSTLF) in streptozotocin-induced diabetic kidney disease mice (DKD) mice.

METHODS

Thirty Institute of Cancer Research mice (specific pathogen free, SPF grade) were divided into five groups (n = 6 per group): control, DKD model, DKD model with YSTLF (4.9 g/kg), DKD model with YSTLF (9.8 g/kg), and DKD model with captopril. DKD was induced through a single intraperitoneal injection of streptozotocin (150 mg/kg). Body weight, fasting blood glucose and urine C-peptide levels were measured to assess metabolic regulation by YSTLF. Renal function was evaluated using indicators of glomerular and tubular health. Liver function was assessed by measuring aspartate aminotransferase and alanine aminotransferase levels. Renal pathological changes were examined using hematoxylin/eosin staining and transmission electron microscopy. Inflammatory and apoptosis-related factors were analyzed through enzyme-linked immunosorbent assay, immunohistochemistry, and Western blot analysis.

RESULTS

In DKD mice, fasting blood glucose, C-peptide, 24-hour urine protein (UP) levels, and renal damage were elevated, accompanied by increased inflammation and apoptosis. YSTLF significantly reduced 24-hour UP and C-peptide levels and improved kidney and liver function in DKD mice. YSTLF also mitigated glomerular hypertrophy, basement membrane thickening, and podocyte foot process effacement. It upregulated the expression of the podocyte marker podocalyxin. Furthermore, YSTLF alleviated inflammation and apoptosis, likely by reducing the overexpression of monocyte chemoattractant protein (MCP-1), Bax, and Caspase-3 in the kidneys of DKD mice.

CONCLUSIONS

These findings suggest that YSTLF ameliorates kidney injury by modulating the expression of inflammatory cytokine MCP-1 and the Bax/Caspase-3 apoptosis pathway, providing a potential therapeutic approach for DKD.

FTZ alleviates lipid deposition in diabetic kidney disease by AMPK/ACC/SREBP signaling pathway

Fufang Zhenzhu Tiaozhi capsule (FTZ) is a patented traditional Chinese medicine preparation that has been used clinically for nearly 10 years to treat hyperglycemia, hyperlipidemia, and other glucolipid metabolic diseases. Previous studies have shown that FTZ can improve diabetic kidney disease (DKD). However, the role and mechanism of FTZ in reducing renal lipid accumulation in DKD remain unclear. Phosphorylation of Adenosine 5'-Monophosphate-Activated Protein Kinase (AMPK), a key regulator of energy homeostasis, inhibits Acetyl-CoA Carboxylase (ACC) signaling, thereby reducing fatty acid synthesis and promoting fatty acid oxidation via carnitine palmitoyltransferase-1 (CPT-1). Sterol regulatory element-binding protein 1 (SREBP-1), a transcription factor, regulates lipid metabolism through fatty acid synthesis. This study investigated the anti-lipid accumulation effect and mechanism of FTZ in vitro and in vivo. Streptozotocin (40 mg/kg/d, i.p. for 5 days, consecutively) combined with a high-fat diet (HFD) were used to induce a DKD model in C57BL/6J mice, followed by FTZ (1, 2 g/kg/d, i.g.) or Losartan (30 mg/kg/d, i.g.) treatments for 12 weeks. High glucose (HG, 30 mM) combined with palmitic-acid (PA, 250 µM) were used to induce HK-2 cells injury, followed by FTZ (25, 50, or 100 µg/ml) or Compound C (an AMPK inhibitor, 10 µM) treatments for 24 h. Results showed that FTZ reduced blood lipids and improved renal function in DKD mice. In addition, compared with the control group, DKD mice and cells exhibited significantly increased lipid deposition. However, the effect of FTZ in alleviating lipid accumulation was reversed by Compound C. Furthermore, FTZ increased p-AMPK, p-ACC and CPT-1 protein expression while decreasing SREBP-1. These results indicate that FTZ effectively protects against lipid accumulation in DKD by regulating the AMPK/ACC/SREBP pathway, inhibiting de novo lipogenesis, providing a novel therapeutic strategy for DKD.

Vascular endothelial growth factor B-mediated fatty acid flux in the adipose-kidney axis contributes to lipotoxicity in diabetic kidney disease

A common observation in diabetic kidney disease is lipid accumulation, but the mechanism(s) underlying this pathology is unknown. Inhibition of Vascular endothelial growth factor B (VEGF-B) signaling was shown to prevent glomerular lipid accumulation and ameliorated diabetic kidney disease in experimental models. Here, we examined kidney biopsies from patients with Type 2 (84%) and Type 1 diabetes (16%), combined with data mining of RNA-seq dataset analyses in patients with diabetic kidney disease. In glomeruli, mesangial cell-derived VEGF-B expression was increased, and glomerular lipid accumulation positively correlated with impaired kidney function. Tubular lipid accumulation also associated with kidney dysfunction but was independent of tubular-derived VEGF-B expression. In vitro, the uptake of the fatty acid analogue, BODIPY-FA, was quantified. VEGF-B treatment increased BODIPY-FA uptake in endothelial cells, whilst pre-incubation with neutralizing antibodies against VEGF-B and its receptor VEGFR1 abolished this uptake. Transcriptome analyses of kidney and white adipose tissue from diabetic macaques showed that VEGF-B expression was higher in white adipose tissue than in kidney, and expression of VEGF-B was increased in white adipose tissue from patients with diabetic kidney disease. Analyses in diabetic transgenic mice demonstrated that expression of VEGF-B in adipocytes determined the lipolytic activity, dyslipidemia, kidney lipid accumulation and the development of diabetic kidney disease. Overall, VEGF-B is a regulator of kidney lipotoxicity in diabetic kidney disease, by controlling white adipose tissue lipolysis as well as endothelial fatty acid transport in glomeruli. Our data propose that assessment of kidney lipid accumulation, and VEGF-B expression can serve as biomarkers for early diabetic kidney disease.

Ang-1 and VEGF: central regulators of angiogenesis

Angiopoietin-1 (Ang-1) and Vascular Endothelial Growth Factor (VEGF) are central regulators of angiogenesis and are often inactivated in various cardiovascular diseases. VEGF forms complexes with ETS transcription factor family and exerts its action by downregulating multiple genes. Among the target genes of the VEGF-ETS complex, there are a significant number encoding key angiogenic regulators. Phosphorylation of the VEGF-ETS complex releases transcriptional repression on these angiogenic regulators, thereby promoting their expression. Ang-1 interacts with TEK, and this phosphorylation release can be modulated by the Ang-1-TEK signaling pathway. The Ang-1-TEK pathway participates in the transcriptional activation of VEGF genes. In summary, these elements constitute the Ang-1-TEK-VEGF signaling pathway. Additionally, Ang-1 is activated under hypoxic and inflammatory conditions, leading to an upregulation in the expression of TEK. Elevated TEK levels result in the formation of the VEGF-ETS complex, which, in turn, downregulates the expression of numerous angiogenic genes. Hence, the Ang-1-dependent transcriptional repression is indirect. Reduced expression of many target genes can lead to aberrant angiogenesis. A significant overlap exists between the target genes regulated by Ang-1-TEK-VEGF and those under the control of the Ang-1-TEK-TSP-1 signaling pathway. Mechanistically, this can be explained by the replacement of the VEGF-ETS complex with the TSP-1 transcriptional repression complex at the ETS sites on target gene promoters. Furthermore, VEGF possesses non-classical functions unrelated to ETS and DNA binding. Its supportive role in TSP-1 formation may be exerted through the VEGF-CRL5-VHL-HIF-1α-VH032-TGF-β-TSP-1 axis. This review assesses the regulatory mechanisms of the Ang-1-TEK-VEGF signaling pathway and explores its significant overlap with the Ang-1-TEK-TSP-1 signaling pathway.

Metabolism at the crossroads of inflammation and fibrosis in chronic kidney disease

Chronic kidney disease (CKD), defined as persistent (>3 months) kidney functional loss, has a growing prevalence (>10% worldwide population) and limited treatment options. Fibrosis driven by the aberrant accumulation of extracellular matrix is the final common pathway of nearly all types of chronic repetitive injury in the kidney and is considered a hallmark of CKD. Myofibroblasts are key extracellular matrix-producing cells that are activated by crosstalk between damaged tubules and immune cells. Emerging evidence indicates that metabolic alterations are crucial contributors to the pathogenesis of kidney fibrosis by affecting cellular bioenergetics and metabolite signalling. Immune cell functions are intricately connected to their metabolic characteristics, and kidney cells seem to undergo cell-type-specific metabolic shifts in response to damage, all of which can determine injury and repair responses in CKD. A detailed understanding of the heterogeneity in metabolic reprogramming of different kidney cellular subsets is essential to elucidating communication processes between cell types and to enabling the development of metabolism-based innovative therapeutic strategies against CKD.

The dual role of lipids in chronic kidney disease: Pathogenic culprits and therapeutic allies

Chronic kidney disease (CKD) is a significant health burden, with rising incidence and prevalence, attributed in part to increasing obesity and diabetes rates. Lipid accumulation in the kidney parenchyma and chronic, low-grade inflammation are believed to significantly contribute to the development and progression of CKD. The effect of dysregulated kidney lipid metabolism in CKD progression, including altered cholesterol and fatty acid metabolism contribute to glomerular and tubular cell injury through the activation of oxidative stress and inflammatory signalling cascades. In contrast, classes of endogenous specialized pro-resolving lipid mediators (SPMs) have been described that act to limit the inflammatory response and promote the resolution of inflammation. This review highlights our current understanding of how lipids can cause damage within the kidney, and classes of protective lipid metabolites that offer therapeutic benefits.

VEGFB ameliorates insulin resistance in NAFLD via the PI3K/AKT signal pathway

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the most universal liver diseases with complicated pathogenesis throughout the world. Insulin resistance is a leading risk factor that contributes to the development of NAFLD. Vascular endothelial growth factor B (VEGFB) was described by researchers as contributing to regulating lipid metabolic disorders. Here, we investigated VEGFB as a main target to regulate insulin resistance and metabolic syndrome.

METHODS

In this study, bioinformatics, transcriptomics, morphological experiments, and molecular biology were used to explore the role of VEGFB in regulating insulin resistance in NAFLD and its molecular mechanism based on human samples, animal models, and cell models. RNA-seq was performed to analyze the signal pathways associated with VEGFB and NAFLD; Palmitic acid and High-fat diet were used to induce insulin-resistant HepG2 cells model and NAFLD animal model. Intracellular glucolipid contents, glucose uptake, hepatic and serum glucose and lipid levels were examined by Microassay and Elisa. Hematoxylin-eosin staining, Oil Red O staining, and Periodic acid-schiff staining were used to analyze the hepatic steatosis, lipid droplet, and glycogen content in the liver. Western blot and quantitative real-time fluorescent PCR were used to verify the expression levels of the VEGFB and insulin resistance-related signals PI3K/AKT pathway.

RESULTS

We observed that VEGFB is genetically associated with NAFLD and the PI3K/AKT signal pathway. After VEGFB knockout, glucolipids levels were increased, and glucose uptake ability was decreased in insulin-resistant HepG2 cells. Meanwhile, body weight, blood glucose, blood lipids, and hepatic glucose of NAFLD mice were increased, and hepatic glycogen, glucose tolerance, and insulin sensitivity were decreased. Moreover, VEGFB overexpression reduced glucolipids and insulin resistance levels in HepG2 cells. Specifically, VEGFB/VEGFR1 activates the PI3K/AKT signals by activating p-IRS1Ser307 expression, inhibiting p-FOXO1pS256 and p-GSK3Ser9 expressions to reduce gluconeogenesis and glycogen synthesis in the liver. Moreover, VEGFB could also enhance the expression level of GLUT2 to accelerate glucose transport and reduce blood glucose levels, maintaining glucose homeostasis.

CONCLUSIONS

Our studies suggest that VEGFB could present a novel strategy for treating NAFLD as a positive factor.

PGC-1α-mediated imbalance of mitochondria-lipid droplet homeostasis in neomycin-induced ototoxicity and nephrotoxicity

Ototoxicity and nephrotoxicity are the most prevalent side effects of aminoglycoside antibiotics (gentamicin, amikacin, neomycin) and platinum anti-tumor drugs (cisplatin, carboplatin). The inner ear and kidney share similarities in drug deposition and toxicity, but the underlying pathophysiological mechanisms remain unclear. Investigating the shared mechanisms and metabolic alterations in these distinct organs will provide valuable insights for clinical therapy. A strong correlation has been identified between the spatiotemporal accumulation patterns of neomycin and the specific occurrence of lipid metabolism disorders in these two organs. The primary allocation of neomycin to mitochondria results in a notable escalation in the accumulation of lipid droplets (LDs) and more interactions between mitochondria and LDs, leading to a sequence of disturbances in lipid metabolism, such as increased lipid ROS and the blocked transfer of fatty acids from LDs to mitochondria. PGC-1α deficiency worsens the neomycin-induced disorders in lipid metabolism and intensifies the pathological interactions between mitochondria and LDs, as indicated by the exacerbated disturbance of dynamic LD turnover, increased level of oxidized lipids and decreased use of fatty acids. This investigation provides a fresh perspective on the lipid metabolic dysfunction related to mitochondria-LD interactions in drug-induced ototoxicity and nephrotoxicity, potentially providing novel avenues for intervention strategies.

Molecular characterization of vascular endothelial growth factor b from spotted sea bass (Lateolabrax maculatus) and its potential roles in decreasing lipid deposition

Vascular endothelial growth factor B (VEGFB), a member of the VEGF family, exhibits limited angiogenic activity in mammals but plays an unexpected role in targeting lipids to peripheral tissues. However, its role in lipid metabolism in fish is unknown. In this study, the vegfb gene was cloned and characterized from spotted sea bass (Lateolabrax maculatus). It encodes 254 amino acids and possesses the typical characteristics of the Vegfb family, demonstrating high homology with those from other vertebrate species. The vegfb gene exhibits the highest expression levels in the liver, followed by the gills, intestine, and adipose tissues in spotted sea bass. In vivo, high-lipid diets decreased vegfb expression and increased lipid deposition in liver of fish. In vitro, palmitic acid + oleic acid treatment or vegfb knockdown significantly increased TG and TC contents, promoting lipid droplet deposition in hepatocytes. Vegfb overexpression has the opposite effects, inhibiting lipid deposition and downregulating fatty acid transport and adipogenesis genes. In contrast, the vegfb knockdown significantly upregulated the expression levels of c/ebpα, plin2, and dgat1 (P < 0.05). These results demonstrate that Vegfb may play an important role in reducing lipid deposition by regulating fatty acid transport and adipogenesis in the hepatocytes of spotted sea bass.

Analysis aqueous humor lipid profile of neovascular glaucoma secondary to diabetic retinopathy and lipidomic alteration response to anti-VEGF treatment

The objective of this study was to examine the lipid spectrum of aqueous humor (AH) in patients with neovascular glaucoma (NVG) secondary to proliferative diabetic retinopathy and to investigate the lipid alteration response to anti-vascular endothelial growth factor (anti-VEGF) treatment. Lipidomic analysis using ultra-high performance liquid chromatography-tandem mass spectrometry was conducted to compare the lipid profiles of the AH in NVG patients with those of a control group. Lipid changes in the AH of NVG patients before and after intravitreal conbercept injections were also evaluated. The identification of lipids showing differential expression was accomplished through both multivariate and univariate analyses. This study included 13 NVG patients and 20 control subjects. Based on LipidSearch software, 639 lipid species across 33 lipid classes were detected in the participants' AH. The combination of univariate and multivariate statistical analyses yielded 53 differentially expressed lipids (VIP >1 and P < 0.05). In addition, 9 lipids were found to be differentially expressed before and after the intravitreal conbercept injections in the NVG patients. Significant alterations in the metabolic pathways of glycerophospholipid and glycerolipid exhibited notable changes. Our results highlighted the lipid changes in patients' AH in relation to the progression of NVG, and indicated that the modified lipids could potentially be utilized as therapeutic targets for NVG.

Rutin mitigates fluoride-induced nephrotoxicity by inhibiting ROS-mediated lysosomal membrane permeabilization and the GSDME-HMGB1 axis involved in pyroptosis and inflammation

Fluoride is known to induce nephrotoxicity; however, the underlying mechanisms remain incompletely understood. Therefore, this study aims to explore the roles and mechanisms of lysosomal membrane permeabilization (LMP) and the GSDME/HMGB1 axis in fluoride-induced nephrotoxicity and the protective effects of rutin. Rutin, a naturally occurring flavonoid compound known for its antioxidative and anti-inflammatory properties, is primarily mediated by inhibiting oxidative stress and reducing proinflammatory markers. To that end, we established in vivo and in vitro models. In the in vivo study, rats were exposed to sodium fluoride (NaF) throughout pregnancy and up until 2 months after birth. In parallel, we employed in vitro models using HK-2 cells treated with NaF, n-acetyl-L-cysteine (NAC), or rutin. We assessed lysosomal permeability through immunofluorescence and analyzed relevant protein expression via western blotting. Our findings showed that NaF exposure increased ROS levels, resulting in enhanced LMP and increased cathepsin B (CTSB) and D (CTSD) expression. Furthermore, the exposure to NaF resulted in the upregulation of cleaved PARP1, cleaved caspase-3, GSDME-N, and HMGB1 expressions, indicating cell death and inflammation-induced renal damage. Rutin mitigates fluoride-induced nephrotoxicity by suppressing ROS-mediated LMP and the GSDME/HMGB1 axis, ultimately preventing fluoride-induced renal toxicity occurrence and development. In conclusion, our findings suggest that NaF induces renal damage through ROS-mediated activation of LMP and the GSDME/HMGB1 axis, leading to pyroptosis and inflammation. Rutin, a natural antioxidative and anti-inflammatory dietary supplement, offers a novel approach to prevent and treat fluoride-induced nephrotoxicity.

Neferine inhibits the progression of diabetic nephropathy by modulating the miR-17-5p/nuclear factor E2-related factor 2 axis

OBJECTIVE

To investigate the effect of Neferine (Nef) on diabetic nephropathy (DN) and to explore the mechanism of Nef in DN based on miRNA regulation theory.

METHODS

A DN mouse model was constructed and treated with Nef. Serum creatinine (Crea), blood urea (UREA) and urinary albumin were measured in mice by kits, and renal histopathological changes and fibrosis were observed by hematoxylin-eosin staining and Masson staining. Renal tissue superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) activities were measured by enzyme-linked immunosorbent assay (ELISA). Western blotting was used to detect the expression of nuclear factor E2-related factor 2 (Nrf2)/ heme oxygenase 1 (HO-1) signaling pathway-related proteins in kidney tissues. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the expression of miR-17-5p in kidney tissues. Subsequently, a DN in vitro model was constructed by high glucose culture of human mesangial cells (HMCs), cells were transfected with miR-17-5p mimic and/or treated with Nef, and we used qRT-PCR to detect cellular miR-17 expression, flow cytometry to detect apoptosis, ELISAs to detect cellular SOD, MDA, and GSH-Px activities, Western blots to detect Nrf2/HO-1 signaling pathway-related protein expression, and dual luciferase reporter gene assays to verify the targeting relationship between Nrf2 and miR-17-5p.

RESULTS

Administration of Nef significantly reduced the levels of blood glucose, Crea, and UREA and the expression of miR-17-5p, improved renal histopathology and fibrosis, significantly reduced MDA levels, elevated SOD and GSH-Px activities, and activated Nrf2 expression in kidney tissues from mice with DN. Nrf2 is a post-transcriptional target of miR-17-5p. In HMCs transfected with miR-17-5p mimics, the mRNA and protein levels of Nrf2 were significantly suppressed. Furthermore, miR-17-5p overexpression and Nef intervention resulted in a significant increase in high glucose-induced apoptosis and MDA levels in HMCs and a significant decrease in the protein expression of HO-1 and Nrf2.

CONCLUSION

Collectively, these results indicate that Nef has an ameliorative effect on DN, and the mechanism may be through the miR-17-5p/Nrf2 pathway.

Melatonin attenuates diabetic cardiomyopathy by increasing autophagy of cardiomyocytes via regulation of VEGF-B/GRP78/PERK signaling pathway

AIMS

Diabetic cardiomyopathy (DCM) is a major cause of mortality in patients with diabetes, and the potential strategies for treating DCM are insufficient. Melatonin (Mel) has been shown to attenuate DCM, however, the underlying mechanism remains unclear. The role of vascular endothelial growth factor-B (VEGF-B) in DCM is little known. In present study, we aimed to investigate whether Mel alleviated DCM via regulation of VEGF-B and explored its underlying mechanisms.

METHODS AND RESULTS

We found that Mel significantly alleviated cardiac dysfunction and improved autophagy of cardiomyocytes in type 1 diabetes mellitus (T1DM) induced cardiomyopathy mice. VEGF-B was highly expressed in DCM mice in comparison with normal mice, and its expression was markedly reduced after Mel treatment. Mel treatment diminished the interaction of VEGF-B and Glucose-regulated protein 78 (GRP78) and reduced the interaction of GRP78 and protein kinase RNA -like ER kinase (PERK). Furthermore, Mel increased phosphorylation of PERK and eIF2α, then up-regulated the expression of ATF4. VEGF-B-/- mice imitated the effect of Mel on wild type diabetic mice. Interestingly, injection with Recombinant adeno-associated virus serotype 9 (AAV9)-VEGF-B or administration of GSK2656157 (GSK), an inhibitor of phosphorylated PERK abolished the protective effect of Mel on DCM. Furthermore, rapamycin, an autophagy agonist displayed similar effect with Mel treatment; while 3-Methyladenine (3-MA), an autophagy inhibitor neutralized the effect of Mel on high glucose-treated neonatal rat ventricular myocytes.

CONCLUSIONS

These results demonstrated that Mel attenuated DCM via increasing autophagy of cardiomyocytes, and this cardio-protective effect of Mel was dependent on VEGF-B/GRP78/PERK signaling pathway.

Traditional Chinese medicine for the treatment of immune-related nephropathy: A review

Immune-related nephropathy (IRN) refers to immune-response-mediated glomerulonephritis and is the main cause of end-stage renal failure. The pathogenesis of IRN is not fully understood; therefore, treatment is challenging. Traditional Chinese medicines (TCMs) have potent clinical effects in the treatment of the IRN conditions immunoglobulin A nephropathy, lupus nephropathy, and diabetic nephropathy. The underlying mechanisms mainly include its inhibition of inflammation; improvements to renal interstitial fibrosis, oxidative stress, autophagy, apoptosis; and regulation of immunity. In this review, we summarize the clinical symptoms of the three IRN subtypes and the use of TCM prescriptions, herbs, and bioactive compounds in treating IRN, as well as the potential mechanisms, intending to provide a reference for the future study of TCM as IRN treatments.

Exosome miR-30a-5p Regulates Glomerular Endothelial Cells' EndMT and Angiogenesis by Modulating Notch1/VEGF Signaling Pathway

BACKGROUND

Diabetic nephropathy (DN) is one of the microvascular complications of diabetes. Endothelial-mesenchymal transition (EndMT) and endothelial damage lead to abnormal angiogenesis in DN.

OBJECTIVES

This study aimed to investigate the role of exosome miR-30a-5p in high glucose (HG)-induced glomerular endothelial cells (GECs) dysfunction and explore the underlying mechanisms.

METHODS

GECs were cultured in normal glucose (5.5 mM) and HG (30 mM) conditions. The recipient GECs were transfected with exosome or miR-30a-5p mimic/inhibitor and then detected by using CCK-8 and flow cytometry assay. Luciferase analysis was used to verify miR-30a-5p acted on notch homolog protein 1 (Notch1). RT-qPCR and Western blot were used to detect the expression of VE-cadherin, α-SMA, vascular endothelial growth factor (VEGF) and Notch1. In vivo, exosome miR-30a-5p was administered to DN mice, and periodic acid-Schiff (PAS) staining, UTP levels, and HbA1c levels were measured.

RESULTS

The expression of miR-30a-5p was downregulated in HG-treated GECs. Exosome miR-30a-5p significantly promoted cell proliferation, and migration and reduced apoptosis of GECs under HG conditions. MiR-30a-5p directly targeted the 3-UTR region of Notch1. Exosome miR-30a-5p reduced the expression levels of Notch1 and VEGF, both at mRNA and protein levels. Furthermore, exosome miR-30a-5p inhibited HG-induced EndMT, as evidenced by increased VE-cadherin and reduced α-SMA. In vivo studies demonstrated that exosome miR-30a-5p reduced serum HbA1c levels and 24-hour urine protein quantification.

CONCLUSION

This study provides evidence that exosome miR-30a-5p suppresses EndMT and abnormal angiogenesis of GECs by modulating the Notch1/VEGF signaling pathway. These findings suggest that exosome miR-30a-5p could be a potential therapeutic strategy for the treatment of DN.

Atractylodes macrocephala Koidz polysaccharide improves glycolipid metabolism disorders through activation of aryl hydrocarbon receptor by gut flora-produced tryptophan metabolites

Polysaccharides are known to confer protection against glycolipid metabolism disorders (GMD) by regulating intestinal flora. In this study, a heterogeneous acidic heteropolysaccharide with high molecular weight mainly composed of fructose was isolated from Atractylodes macrocephala Koidz (AMP). Supplementation with AMP was shown to improve diet-induced GMD in a rat model, including decreasing the levels of serum triglycerides, total cholesterol, and glucose, and improving hepatic lipidosis and islet cells morphologies. AMP-treated rats also exhibited modified intestinal flora with enrichments of intestinal Lactobacillus and Rothia species, which was accompanied by increased tryptophan metabolites such as indole-3-propionic acid, indole, tryptamine, and tryptophol. These metabolites promote the expression of intestinal aryl hydrocarbon receptor (AhR) in nuclear fractions. AhR activation increased the expression levels of IL-22 and GLP-1 proteins and mRNA. IL-22 reduced systemic LPS by upregulating the expression of tight junction proteins, antimicrobial peptides, and mucin to ameliorate intestinal barrier function, and activated the hepatic IL-22R/Stat3/Acox1 signaling pathway to improve lipid metabolism. GLP-1 activated the pancreatic GLP-1R/p-CREB signaling pathway to ameliorate β-cell injury and improve insulin resistance. Therefore, the intestinal microbial-tryptophan metabolism-AhR pathway was deduced to be a mechanism by which this polysaccharide improves GMD.

Vascular endothelial growth factor B regulates insulin secretion in β cells of type 2 diabetes mellitus mice via PLCγ and the IP3R‑evoked Ca2+/CaMK2 signaling pathway

Vascular endothelial growth factor B (VEGFB) plays a crucial role in glucolipid metabolism and is highly associated with type 2 diabetes mellitus (T2DM). The role of VEGFB in the insulin secretion of β cells remains unverified. Thus, the present study aimed to discuss the effect of VEGFB on regulating insulin secretion in T2DM development, and its underlying mechanism. A high‑fat diet and streptozocin (STZ) were used for inducing T2DM in mice model, and VEGFB gene in islet cells of T2DM mice was knocked out by CRISPR Cas9 and overexpressed by adeno‑Associated Virus (AAV) injection. The effect of VEGFB and its underlying mechanism was assessed by light microscopy, electron microscopy and fluorescence confocal microscopy, enzyme‑linked immunosorbent assay, mass spectrometer and western blot analysis. The decrement of insulin secretion in islet β cell of T2DM mice were aggravated and blood glucose remained at a high level after VEGFB knockout (KO). However, glucose tolerance and insulin sensitivity of T2DM mice were improved after the AAV‑VEGFB186 injection. VEGFB KO or overexpression can inhibit or activate PLCγ/IP3R in a VEGFR1‑dependent manner. Then, the change of PLCγ/IP3R caused by VEGFB/VEGFR1 will alter the expression of key factors on the Ca2+/CaMK2 signaling pathway such as PPP3CA. Moreover, VEGFB can cause altered insulin secretion by changing the calcium concentration in β cells of T2DM mice. These findings indicated that VEGFB activated the Ca2+/CaMK2 pathway via VEGFR1‑PLCγ and IP3R pathway to regulate insulin secretion, which provides new insight into the regulatory mechanism of abnormal insulin secretion in T2DM.

The role of cellular crosstalk in the progression of diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common complications of diabetes, and its main manifestations are progressive proteinuria and abnormal renal function, which eventually develops end stage renal disease (ESRD). The pathogenesis of DN is complex and involves many signaling pathways and molecules, including metabolic disorders, genetic factors, oxidative stress, inflammation, and microcirculatory abnormalities strategies. With the development of medical experimental techniques, such as single-cell transcriptome sequencing and single-cell proteomics, the pathological alterations caused by kidney cell interactions have attracted more and more attention. Here, we reviewed the characteristics and related mechanisms of crosstalk among kidney cells podocytes, endothelial cells, mesangial cells, pericytes, and immune cells during the development and progression of DN and highlighted its potential therapeutic effects.

Role of vascular endothelial growth factor B in nonalcoholic fatty liver disease and its potential value

Nonalcoholic fatty liver disease (NAFLD) refers to fatty liver disease caused by liver injury factors other than alcohol. The disease is characterized by diffuse fat infiltration, including simple steatosis (no inflammatory fat deposition), nonalcoholic fatty hepatitis, liver fibrosis, and so on, which may cause liver cirrhosis, liver failure, and even liver cancer in the later stage of disease progression. At present, the pathogenesis of NAFLD is still being studied. The "two-hit" theory, represented by lipid metabolism disorder and inflammatory reactions, is gradually enriched by the "multiple-hit" theory, which includes multiple factors, such as insulin resistance and adipocyte dysfunction. In recent years, vascular endothelial growth factor B (VEGFB) has been reported to have the potential to regulate lipid metabolism and is expected to become a novel target for ameliorating metabolic diseases, such as obesity and type 2 diabetes. This review summarizes the regulatory role of VEGFB in the onset and development of NAFLD and illustrates its underlying molecular mechanism. In conclusion, the signaling pathway mediated by VEGFB in the liver may provide an innovative approach to the diagnosis and treatment of NAFLD.

Aptamers Versus Vascular Endothelial Growth Factor (VEGF): A New Battle against Ovarian Cancer

Cancer is one of the diseases that causes a high mortality as it involves unregulated and abnormal cell growth proliferation that can manifest in any body region. One of the typical ovarian cancer symptoms is damage to the female reproductive system. The death rate can be reduced through early detection of the ovarian cancer. Promising probes that can detect ovarian cancer are suitable aptamers. Aptamers, i.e., so-called chemical antibodies, have a strong affinity for the target biomarker and can typically be identified starting from a random library of oligonucleotides. Compared with other probes, ovarian cancer targeting using aptamers has demonstrated superior detection effectiveness. Various aptamers have been selected to detect the ovarian tumor biomarker, vascular endothelial growth factor (VEGF). The present review highlights the development of particular aptamers that target VEGF and detect ovarian cancer at its earliest stages. The therapeutic efficacy of aptamers in ovarian cancer treatment is also discussed.

Inhibition of Fatty Acid β-Oxidation by Fatty Acid Binding Protein 4 Induces Ferroptosis in HK2 Cells Under High Glucose Conditions

BACKGRUOUND

Ferroptosis, which is caused by an iron-dependent accumulation of lipid hydroperoxides, is a type of cell death linked to diabetic kidney disease (DKD). Previous research has shown that fatty acid binding protein 4 (FABP4) is involved in the regulation of ferroptosis in diabetic retinopathy. The present study was constructed to explore the role of FABP4 in the regulation of ferroptosis in DKD.

METHODS

We first detected the expression of FABP4 and proteins related to ferroptosis in renal biopsies of patients with DKD. Then, we used a FABP4 inhibitor and small interfering RNA to investigate the role of FABP4 in ferroptosis induced by high glucose in human renal proximal tubular epithelial (HG-HK2) cells.

RESULTS

In kidney biopsies of DKD patients, the expression of FABP4 was elevated, whereas carnitine palmitoyltransferase-1A (CP-T1A), glutathione peroxidase 4, ferritin heavy chain, and ferritin light chain showed reduced expression. In HG-HK2 cells, the induction of ferroptosis was accompanied by an increase in FABP4. Inhibition of FABP4 in HG-HK2 cells changed the redox state, sup-pressing the production of reactive oxygen species, ferrous iron (Fe2+), and malondialdehyde, increasing superoxide dismutase, and reversing ferroptosis-associated mitochondrial damage. The inhibition of FABP4 also increased the expression of CPT1A, reversed lipid deposition, and restored impaired fatty acid β-oxidation. In addition, the inhibition of CPT1A could induce ferroptosis in HK2 cells.

CONCLUSION

Our results suggest that FABP4 mediates ferroptosis in HG-HK2 cells by inhibiting fatty acid β-oxidation.

A bifunctional fusion protein protected against diabetic nephropathy by suppressing NLRP3 activation

Diabetic nephropathy (DN), the principal pathogeny of end-stage renal disease (ESRD), is related to metabolic disorders, chronic inflammation, and oxidative stress. It was reported that high expression of interleukin-17A (IL-17A) was intimately related to the progression of DN, and targeting IL-17A exhibited regulating effects on inflammation and autoimmunity but had only limited impact on the oxidative stress damage in DN. Recent studies showed that interleukin-22 (IL-22) could inhibit mitochondrial damage and inflammatory response. Thus, the cytokine IL-22 was first fused to anti-IL-17A antibody for endowing the antibody with the anti-hyperglycemia and anti-inflammation activity. Our study demonstrated that the fusion molecule, anti-IL17A/IL22 fusion protein, could not only lead to the increase of M1 macrophages and the decrease of M2 macrophages, further improving the immune microenvironment, but also prevent the loss of mitochondrial membrane potential by reducing the production of ROS in murine DN model. In addition, the fusion protein could block TRAF6/NF-κB and AKT/ROS/TXNIP signaling pathways, further synergistically restraining the production of NLRP3, thus suppressing the inflammatory response and playing beneficial effect on slowing down the progression of DN. In conclusion, our findings demonstrated that the bifunctional IL-17A antibody and IL-22 fusion protein were of great benefit to DN, which highlighted a potential therapeutic strategy. KEY POINTS: • Anti-IL17A/IL22 fusion protein could improve the immune microenvironment and reduce the production of ROS. • Anti-IL17A/IL22 fusion protein could block TRAF6/NF-κB and AKT/ROS/TXNIP signaling pathways and then restrain the activation of NLRP3.

Simultaneous blockade of VEGF-B and IL-17A ameliorated diabetic kidney disease by reducing ectopic lipid deposition and alleviating inflammation response

The pathogenesis of diabetic kidney disease (DKD) is complicated. Current clinical treatments fail to achieve satisfactory efficacy in the prevention of DKD progression, it urgently needs novel and effective treatment for DKD. In this study, we firstly demonstrated that renal lipid metabolism abnormality and inflammation significantly changed in DKD conditions by mining public transcriptomic data of DKD patient samples. KEGG analysis further exhibited the critical role of vascular endothelial growth factor B (VEGF-B) and interleukin 17A (IL-17A) signal pathways in DKD progression, indicating that VEGF-B and IL-17A might be the promising targets for DKD treatment. Then the potential of a novel combination therapy, anti-VEGF-B plus anti-IL-17A antibody, was evaluated for DKD treatment. Our results demonstrated that simultaneous blockade of VEGF-B and IL-17A signaling with their neutralizing antibodies alleviated renal damage and ameliorated renal function. The therapeutic effectiveness was not only related to the reduced lipid deposition especially the neutral lipids in kidney but also associated with the decreased inflammation response. Moreover, the therapy alleviated renal fibrosis by reducing collagen deposition and the expression of fibronectin and α-SMA in kidney tissues. RNA-seq analysis indicated that differential expression genes (DEGs) in db/db mice were significantly clustered into lipid metabolism, inflammation, fibrosis and DKD pathology-related pathways, and 181 of those DEGs were significantly reversed by the combinatory treatment, suggesting the underlying mechanism of administration of anti-VEGF-B and anti-IL-17A antibodies in DKD treatment. Taken together, this study identified that renal lipid metabolism abnormality and inflammation were critically involved in the progression of DKD, and simultaneous blockade of VEGF-B and IL-17A signaling represents a potential DKD therapeutic strategy.

The Role of VEGF Family in Lipid Metabolism

The vascular endothelial growth factor (VEGF) family plays a major role in tumors and ophthalmic diseases. However, increasingly more data reported its potential in regulating lipids. With its biological functions mainly expressed in lymphatic vessels, some factors in the families, like VEGF-A and VEGF-C, have been proved to regulate intestinal absorption of lipids by affecting chylous ducts. Other effects, including regulating lipoprotein lipase (LPL), endothelial lipase (EL), and recombinant syndecan 1 (SDC1), have also been confirmed. However, given the scant-related studies, further research should be conducted to examine the concrete mechanisms and provide pragmatic ways to apply them in the clinic. The VEGF family may treat dyslipidemia in specific ways that are different from common methods and concurrently contribute to the treatment of other metabolic diseases, like diabetes and obesity.

A novel fusion protein consisting of anti-ANGPTL3 antibody and interleukin-22 ameliorates diabetic nephropathy in mice

Introduction

The pathogenic mechanisms of diabetic nephropathy (DN) include podocyte injury, inflammatory responses and metabolic disorders. Although the antagonism of Angiopoietin-like protein 3 (ANGPTL3) can alleviate proteinuria symptoms by inhibiting the activation of integrin αvβ3 on the surface of podocytes, it can not impede other pathological processes, such as inflammatory responses and metabolic dysfunction of glucolipid. Interleukin-22 (IL-22) is considered to be a pivotal molecule involved in suppressing inflammatory responses, initiating regenerative repair, and regulating glucolipid metabolism.

Methods

Genes encoding the mIL22IgG2aFc and two chains of anti-ANGPTL3 antibody and bifunctional protein were synthesized. Then, the DN mice were treated with intraperitoneal injection of normal saline, anti-ANGPTL3 (20 mg/kg), mIL22Fc (12 mg/kg) or anti-ANGPTL3 /IL22 (25.3 mg/kg) and irrigation of positive drug losartan (20mg/kg/d) twice a week for 8 weeks.

Results

In this research, a novel bifunctional fusion protein (anti-ANGPTL3/IL22) formed by the fusion of IL-22 with the C-terminus of anti-ANGPTL3 antibody exhibited favorable stability and maintained the biological activity of anti-ANGPTL3 and IL-22, respectively. The fusion protein showed a more pronounced attenuation of proteinuria and improved dysfunction of glucolipid metabolism compared with mIL22Fc or anti-ANGPTL3. Our results also indicated that anti-ANGPTL3/IL22 intervention significantly alleviated renal fibrosis via inhibiting the expression of the inflammatory response-related protein nuclear factor kappa light-chain enhancer of activated B cells (NF-κB) p65 and NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome. Moreover, transcriptome analysis revealed the downregulation of signaling pathways associated with injury and dysfunction of the renal parenchymal cell indicating the possible protective mechanisms of anti-ANGPTL3/IL22 in DN.

Conclusion

Collectively, anti-ANGPTL3/IL22 bifunctional fusion protein can be a promising novel therapeutic strategy for DN by reducing podocyte injury, ameliorating inflammatory response, and enhancing renal tissue recovery.

Metabolic reprogramming: A novel therapeutic target in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes mellitus. However, the pathological mechanisms contributing to DKD are multifactorial and poorly understood. Diabetes is characterized by metabolic disorders that can bring about a series of changes in energy metabolism. As the most energy-consuming organs secondary only to the heart, the kidneys must maintain energy homeostasis. Aberrations in energy metabolism can lead to cellular dysfunction or even death. Metabolic reprogramming, a shift from mitochondrial oxidative phosphorylation to glycolysis and its side branches, is thought to play a critical role in the development and progression of DKD. This review focuses on the current knowledge about metabolic reprogramming and the role it plays in DKD development. The underlying etiologies, pathological damages in the involved cells, and potential molecular regulators of metabolic alterations are also discussed. Understanding the role of metabolic reprogramming in DKD may provide novel therapeutic approaches to delay its progression to end-stage renal disease.

Reducing VEGFB expression regulates the balance of glucose and lipid metabolism in mice via VEGFR1

In recent years, studies have demonstrated that vascular endothelial growth factor B (VEGFB) can affect the metabolism of fatty acids and glucose, and it is expected to become a target for the diagnosis and treatment of metabolic diseases such as obesity and diabetes. At present, the specific mechanism that VEGFB regulates lipid and glucose metabolism balance is not completely understood. The present study used systemic VEGFB gene-knockout mice to investigate the effects of downregulation of the VEGFB gene on lipid metabolism and insulin secretion, and to explore the mechanism of the VEGFB pathway involved in the regulation of glucose and lipid metabolism. The morphological changes in the liver and pancreas of mice after VEGFB gene deletion were observed under a light microscope and a scanning electron microscope, and the effects of VEGFB gene deletion on lipid metabolism and blood glucose balance were detected by a serological technique. The detection indexes included total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol. Simultaneously, fasting blood glucose, glycosylated hemoglobin A1c (HbA1c), fasting insulin and glucagon were measured. Insulin sensitivity was assessed by using the insulin tolerance tests and glucose tolerance tests, and function of β-cell islets was evaluated by using the insulin resistance index (HOMA-IR) and pancreatic β-cell secretion index (HOMA-β). Τhe protein expression changes of vascular endothelial growth factor receptor 1 (VEGFR1) and vascular endothelial growth factor receptor 2 (VEGFR2) in mouse islets were detected by western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) after the VEGFB gene was knocked down to analyze the mechanism of VEGFB that may be involved in glucose and lipid metabolism. It was observed that after VEGFB was knocked down, mouse hepatocytes exhibited steatosis and increased secretory vesicles in islet cells. The lipid metabolism indexes such as TG, TC and LDL increased significantly; however, the levels of FBS, postprandial blood glucose and HbA1c decreased, whereas the glucose tolerance increased. Serum insulin secretion increased and HOMA-IR decreased since VEGFB was knocked down. Western blotting and RT-qPCR results revealed that the expression levels of VEGFR1 and neuropilin-1 decreased after the VEGFB gene was knocked down, while the expression levels of VEGFA and VEGFR2 increased. The absence of VEGFB may be involved in the regulation of glucose and lipid metabolism in mice by activating the VEGFA/VEGFR2 signaling pathway. VEGFB is expected to become a new target for the treatment of metabolic diseases such as obesity and diabetes. At present, the mechanism of VEGFB involved in regulating lipid metabolism and glucose metabolism is not completely clear. It was identified that downregulating VEGFB improved lipid metabolism and insulin resistance. The role of VEGFB/VEGFR1 pathway and other family members in regulating glucose and lipid metabolism was detected, which provided a theoretical and experimental basis for VEGFB to affect the regulation of glucose and lipid metabolism balance.

Interleukin-22 in Renal Protection and Its Pathological Role in Kidney Diseases

Chronic kidney injury has gradually become a worldwide public health problem currently affecting approximately 10% of the population and can eventually progress to chronic end-stage renal disease characteristic by the result of epithelial atrophy. Interleukin-22 (IL-22) is a cytokine produced by activated immune cells, while acting mainly on epithelial cells ranging from innate immune response to tissue regeneration to maintain barrier integrity and promote wound healing. Accumulating data suggests that IL-22 has emerged as a fundamental mediator of epithelial homeostasis in the kidney through promoting tissue repair and regeneration, inhibiting oxidative stress, and producing antimicrobial peptides. Binding of IL-22 to its transmembrane receptor complex triggers janus kinase/tyrosine kinase 2 phosphorylation, which further activates a number of downstream cascades, including signal transducer and activator of transcription 3, MAP kinase, and protein kinase B, and initiates a wide array of downstream effects. However, the activation of the IL-22 signaling pathways promotes the activation of complement systems and enhances the infiltration of chemokines, which does harm to the kidney and may finally result in chronic renal failure of different autoimmune kidney diseases, including lupus nephritis, and IgA nephropathy. This review describes current knowledge of the basic features of IL-22, including structure, cellular origin and associated signaling pathways. Also, we summarize the latest progress in understanding the physiological and pathological effects of IL-22 in the kidney, suggesting the potential strategies for the specific application of this cytokine in the treatment of kidney disease.

Increased Serum VEGF-B Level Is Associated With Renal Function Impairment in Patients With Type 2 Diabetes

Aims/Introduction

Renal function impairment related to type 2 diabetes (T2DM) presents serious threat to public health. Previous studies suggest that vascular endothelial growth factor-B (VEGF-B) might contribute to renal injury. Therefore, this study investigated the association of serum VEGF-B level with the risk of renal function impairment in T2DM patients.

Materials and Methods

Serum VEGF-B levels were measured in 213 patients with type 2 diabetes and 31 healthy participants. Participants with type 2 diabetes were further divided into a group of 112 participants with eGFR<90 mL/min/1.73m2 and 101 participants with eGFR≥ 90 mL/min/1.73m2. Clinical data were collected, and a binary logistic regression model was employed to test the association between potential predictors and eGFR.

Results

Serum VEGF-B levels evaluated in type 2 diabetes patients compared with healthy controls. In patients with type 2 diabetes, serum VEGF-B level was positively correlated with triglyceride, serum creatinine and cystatin C while negatively correlated with HDL-C and eGFR. Binary logistic regression showed that serum VEGF-B level was an independent risk factor of eGFR<90 mL/min/1.73m2.

Conclusions

Serum VEGF-B level is associated with renal function impairment in patients with type 2 diabetes and may be a potential drug target for diabetic kidney disease.

Metabolic Dysfunction in the Regulation of the NLRP3 Inflammasome Activation: A Potential Target for Diabetic Nephropathy

Metabolic dysfunction plays a key role in the development of diabetic nephropathy (DN). However, the exact effects and mechanisms are still unclear. The pyrin domain-containing protein 3 (NLRP3) inflammasome, a member of the nod-like receptor family, is considered a crucial inflammatory regulator and plays important roles in the progress of DN. A growing body of evidence suggests that high glucose, high fat, or other metabolite disorders can abnormally activate the NLRP3 inflammasome. Thus, in this review, we discuss the potential function of abnormal metabolites such as saturated fatty acids (SFAs), cholesterol crystals, uric acid (UA), and homocysteine in the NLRP3 inflammasome activation and explain the potential function of metabolic dysfunction regulation of NLRP3 activation in the progress of DN via regulation of inflammatory response and renal interstitial fibrosis (RIF). In addition, the potential mechanisms of metabolism-related drugs, such as metformin and sodium glucose cotransporter (SGLT2) inhibitors, which have served as the suppressors of the NLRP3 inflammasomes, in DN, are also discussed. A better understanding of NLRP3 inflammasome activation in abnormal metabolic microenvironment may provide new insights for the prevention and treatment of DN.

Therapeutic Opportunities of IL-22 in Non-Alcoholic Fatty Liver Disease: From Molecular Mechanisms to Clinical Applications

Nonalcoholic fatty liver disease (NAFLD) represents one of the most common liver disorders and can progress into a series of liver diseases, including nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and even liver cancer. Interleukin-22 (IL-22), a member of the IL-10 family of cytokines, is predominantly produced by lymphocytes but acts exclusively on epithelial cells. IL-22 was proven to favor tissue protection and regeneration in multiple diseases. Emerging evidence suggests that IL-22 plays important protective functions against NAFLD by improving insulin sensitivity, modulating lipid metabolism, relieving oxidative and endoplasmic reticulum (ER) stress, and inhibiting apoptosis. By directly interacting with the heterodimeric IL-10R2 and IL-22R1 receptor complex on hepatocytes, IL-22 activates the Janus kinase 1 (JAK1)/ signal transducer and activator of transcription 3 (STAT3), c-Jun N-terminal kinase (JNK) and extracellular-signal regulated kinase (ERK) pathways to regulate the subsequent expression of genes involved in inflammation, metabolism, tissue repair, and regeneration, thus alleviating hepatitis and steatosis. However, due to the wide biodistribution of the IL-22 receptor and its proinflammatory effects, modifications such as targeted delivery of IL-22 expression and recombinant IL-22 fusion proteins to improve its efficacy while reducing systemic side effects should be taken for further clinical application. In this review, we summarized recent progress in understanding the physiological and pathological importance of the IL-22-IL-22R axis in NAFLD and the mechanisms of IL-22 in the protection of NAFLD and discussed the potential strategies to maneuver this specific cytokine for therapeutic applications for NAFLD.