Elabela protects against podocyte injury in mice with streptozocin-induced diabetes by associating with the PI3K/Akt/mTOR pathway

Potential Metabolic Pathways Involved in Osteoporosis and Evaluation of Fracture Risk in Individuals with Diabetes

Diabetes has a significant global prevalence. Chronic hyperglycemia affects multiple organs and tissues, including bones. A large number of diabetic patients develop osteoporosis; however, the precise relationship between diabetes and osteoporosis remains incompletely elucidated. The activation of the AGE-RAGE signaling pathway hinders the differentiation of osteoblasts and weakens the process of bone formation due to the presence of advanced glycation end products. High glucose environment can induce ferroptosis of osteoblasts and then develop osteoporosis. Hyperglycemia also suppresses the secretion of sex hormones, and the reduction of testosterone is difficult to effectively maintain bone mineral density. As diabetes therapy, thiazolidinediones control blood glucose by activating PPAR-γ. Activated PPAR-γ can promote osteoclast differentiation and regulate osteoblast function, triggering osteoporosis. The effects of metformin and insulin on bone are currently controversial. Currently, there are no appropriate tools available for assessing the risk of fractures in diabetic patients, despite the fact that the occurrence of osteoporotic fractures is considerably greater in diabetic individuals compared to those without diabetes. Further improving the inclusion criteria of FRAX risk factors and clarifying the early occurrence of osteoporosis sites unique to diabetic patients may be an effective way to diagnose and treat diabetic osteoporosis and reduce the risk of fracture occurrence.

Decreased plasma ELABELA level as a novel screening indicator for heart failure: a cohort and observational study

The predictive power of B-type natriuretic peptide (BNP) and left ventricular ejection fraction (LVEF) is limited by its low specificity in patients with heart failure (HF). Discovery of more novel biomarkers for HF better diagnosis is necessary and urgent. ELABELA, an early endogenous ligand for the G protein-coupled receptor APJ (Apelin peptide jejunum, Apelin receptor), exhibits cardioprotective actions. However, the relationship between plasma ELABELA and cardiac function in HF patients is unclear. To evaluate plasma ELABELA level and its diagnostic value in HF patients, a total of 335 patients with or without HF were recruited for our monocentric observational study. Plasma ELABELA and Apelin levels were detected by immunoassay in all patients. Spearman correlation analysis was used to analyze the correlation between plasma ELABELA or Apelin levels and study variables. The receiver operating characteristic curves were used to access the predictive power of plasma ELABELA or Apelin levels. Plasma ELABELA levels were lower, while plasma Apelin levels were higher in HF patients than in non-HF patients. Plasma ELABELA levels were gradually decreased with increasing New York Heart Association grade or decreasing LVEF. Plasma ELABELA levels were negatively correlated with BNP, left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left ventricular posterior wall thickness and positively correlated with LVEF in HF patients. In contrast, the correlation between plasma Apelin levels and these parameters is utterly opposite to ELABELA. The diagnostic value of ELABELA, Apelin, and LVEF for all HF patients was 0.835, 0.673, and 0.612; the sensitivity was 62.52, 66.20, and 32.97%; and the specificity was 95.92, 67.23, and 87.49%, respectively. All these parameters in HF patients with preserved ejection fraction were comparable to those in total HF patients. Overall, plasma ELABELA levels were significantly reduced and negatively correlated with cardiac function in HF patients. Decreased plasma ELABELA levels may function as a novel screening biomarker for HF. A combined assessment of BNP and ELABELA may be a good choice to increase the accuracy of the diagnosis of HF.

Integrated Network Pharmacology Analysis and Experimental Validation to Elucidate the Mechanism of Acteoside in Treating Diabetic Kidney Disease

Background

Acteoside, an active ingredient found in various medicinal herbs, is effective in the treatment of diabetic kidney disease (DKD); however, the intrinsic pharmacological mechanism of action of acteoside in the treatment of DKD remains unclear. This study utilizes a combined approach of network pharmacology and experimental validation to investigate the potential molecular mechanism systematically.

Methods

First, acteoside potential targets and DKD-associated targets were aggregated from public databases. Subsequently, utilizing protein-protein interaction (PPI) networks, alongside GO and KEGG pathway enrichment analyses, we established target-pathway networks to identify core potential therapeutic targets and pathways. Further, molecular docking facilitated the confirmation of interactions between acteoside and central targets. Finally, the conjectured molecular mechanisms of acteoside against DKD were verified through experimentation on unilateral nephrectomy combined with streptozotocin (STZ) rat model. The underlying downstream mechanisms were further investigated.

Results

Network pharmacology identified 129 potential intersected targets of acteoside for DKD treatment, including targets such as AKT1, TNF, Casp3, MMP9, SRC, IGF1, EGFR, HRAS, CASP8, and MAPK8. Enrichment analyses indicated the PI3K-Akt, MAPK, Metabolic, and Relaxin signaling pathways could be involved in this therapeutic context. Molecular docking revealed high-affinity binding of acteoside to PIK3R1, AKT1, and NF-κB1. In vivo studies validated the therapeutic efficacy of acteoside, demonstrating reduced blood glucose levels, improved serum Scr and BUN levels, decreased 24-hour urinary total protein (P<0.05), alongside mitigated podocyte injury (P<0.05) and ameliorated renal pathological lesions. Furthermore, this finding indicates that acteoside inhibits the expression of pyroptosis markers NLRP3, Caspase-1, IL-1β, and IL-18 through the modulation of the PI3K/AKT/NF-κB pathway.

Conclusion

Acteoside demonstrates renoprotective effects in DKD by regulating the PI3K/AKT/NF-κB signaling pathway and alleviating pyroptosis. This study explores the pharmacological mechanism underlying acteoside's efficacy in DKD treatment, providing a foundation for further basic and clinical research.

ELABELA-derived peptide ELA13 attenuates kidney fibrosis by inhibiting the Smad and ERK signaling pathways

Kidney fibrosis is an inevitable result of various chronic kidney diseases (CKDs) and significantly contributes to end-stage renal failure. Currently, there is no specific treatment available for renal fibrosis. ELA13 (amino acid sequence: RRCMPLHSRVPFP) is a conserved region of ELABELA in all vertebrates; however, its biological activity has been very little studied. In the present study, we evaluated the therapeutic effect of ELA13 on transforming growth factor-β1 (TGF-β1)-treated NRK-52E cells and unilateral ureteral occlusion (UUO) mice. Our results demonstrated that ELA13 could improve renal function by reducing creatinine and urea nitrogen content in serum, and reduce the expression of fibrosis biomarkers confirmed by Masson staining, immunohistochemistry, real-time polymerase chain reaction (RT-PCR), and western blot. Inflammation biomarkers were increased after UUO and decreased by administration of ELA13. Furthermore, we found that the levels of essential molecules in the mothers against decapentaplegic (Smad) and extracellular signal-regulated kinase (ERK) pathways were reduced by ELA13 treatment in vivo and in vitro. In conclusion, ELA13 protected against kidney fibrosis through inhibiting the Smad and ERK signaling pathways and could thus be a promising candidate for anti-renal fibrosis treatment.

Protective Effect of Mesenchymal Stem Cell Active Factor Combined with Alhagi maurorum Extract on Ulcerative Colitis and the Underlying Mechanism

Ulcerative colitis (UC) is a relapsing and reoccurring inflammatory bowel disease. The treatment effect of Alhagi maurorum and stem cell extracts on UC remains unclear. The aim of the present study was to investigate the protective role of Alhagi maurorum combined with stem cell extract on the intestinal mucosal barrier in an intestinal inflammation mouse model. Sixty mice were randomly divided into a control group, model group, Alhagi group, MSC group, and MSC/Alhagi group. MSC and Alhagi extract were found to reduce the disease activity index (DAI) scores in mice with colitis, alleviate weight loss, improve intestinal inflammation in mice (p < 0.05), preserve the integrity of the ileal wall and increase the number of goblet cells and mucin in colon tissues. Little inflammatory cell infiltration was observed in the Alhagi, MSC, or MSC/Alhagi groups, and the degree of inflammation was significantly alleviated compared with that in the model group. The distribution of PCNA and TNF-alpha in the colonic tissues of the model group was more disperse than that in the normal group (p < 0.05), and the fluorescence intensity was lower. After MSC/Alhagi intervention, PCNA and TNF-alpha were distributed along the cellular membrane in the MSC/Alhagi group (p < 0.05). Compared with that in the normal control group, the intensity was slightly reduced, but it was still stronger than that in the model group. In conclusion, MSC/Alhagi can alleviate inflammatory reactions in mouse colonic tissue, possibly by strengthening the protective effect of the intestinal mucosal barrier.

QiDiTangShen granules alleviates diabetic nephropathy podocyte injury: A network pharmacology study and experimental validation in vivo and vitro

Background

QiDiTangShen granules (QDTS), a traditional Chinese medicine (TCM) compound prescription, have remarkable efficacy in diabetic nephropathy (DN) patients, and their pharmacological mechanism needs further exploration.

Methods

According to the active ingredients and targets of the QDTS in the TCMSP database, the network pharmacology of QDTS was investigated. The potential active ingredients were chosen based on the oral bioavailability and the drug similarity index. At the same time, targets for DN-related disease were obtained from GeneCards, OMIM, PharmGKB, TTD, and DrugBank. The TCM-component-target network and the protein-protein interaction (PPI) network were constructed with the Cytoscape and STRING platforms, respectively, and then the core targets of DN were selected with CytoNCA. GO and KEGG enrichment analysis using R software. Molecular docking to identify the core targets of QDTS for DN. In vivo, db/db mice were treated as DN models, and the urine microalbuminuria, the pathological changes in the kidney and the protein expression levels of p-PI3K, p-Akt, JUN, nephrin and synaptopodin were detected by immunohistochemistry, immunofluorescence method and Western blotting. After QDTS was used in vitro, the protein expression of mouse podocyte clone-5 (MPC5) cells was detected by immunohistochemistry, immunofluorescence and Western blot.

Results

Through network pharmacology analysis, 153 potential targets for DN in QDTS were identified, 19 of which were significant. The KEGG enrichment analysis indicated that QDTS might have therapeutic effects on IL-17, TNF, AGE-RAGE, PI3K-Akt, HIF-1, and EGFR through interfering with Akt1 and JUN. The main active ingredients in QDTS are quercetin, β-sitosterol, stigmasterol and kaempferol. Both in vivo and in vitro studies showed that QDTS could decrease the urine microalbuminuria and renal pathology of db/db mice, and alleviate podocyte injuries through the PI3K/Akt signaling pathway.

Conclusion

Through network pharmacology, in vivo and in vitro experiments, QDTS has been shown to improve the urine microalbuminuria and renal pathology in DN, and to reduce podocyte damage via the PI3K/Akt pathway.

ELABELA protects against diabetic kidney disease by activating high glucose-inhibited renal tubular autophagy

ELABELA (ELA), an endogenous ligand of the apelin receptor (also known as apelin peptide jejunum [APJ]), has been shown to decrease in the plasma of patients with diabetic kidney disease (DKD). In the current study, we explored the potential function as well as the underlying mechanisms of ELA in DKD. We first found that the ELA levels were decreased in the kidneys of DKD mice. Then, we found that ELA administration mitigated renal damage and downregulated the expression of fibronectin, collagen Ⅳ, and transforming growth factor-β1 in the db/db mice and the high glucose cultured HK-2 cells. Furthermore, the autophagy markers, Beclin-1 and LC3-Ⅱ/LC3-Ⅰ ratio, were significantly impaired in DKD, but the ELA treatment reversed these alterations. Mechanistically, the inhibitory effects of ELA on the secretion of fibrosis-associated proteins in high glucose conditions were blocked by pretreatment with 3-methyladenine (an autophagy inhibitor). In summary, these in vivo and in vitro results demonstrate that ELA effectively protects against DKD by activating high glucose-inhibited renal tubular autophagy, potentially serving as a novel therapeutic candidate for DKD.

A promising therapeutic peptide and preventive/diagnostic biomarker for age-related diseases: The Elabela/Apela/Toddler peptide

Elabela (ELA), Apela or Toddler peptide is a hormone peptide belonging to the adipokine group and a component of apelinergic system, discovered in 2013-2014. Given its high homology with apelin, the first ligand of APJ receptor, ELA likely mediates similar effects. Increasing evidence shows that ELA has a critical function not only in embryonic development, but also in adulthood, contributing to physiological and pathological conditions, such as the onset of age-related diseases (ARD). However, still little is known about the mechanisms and molecular pathways of ELA, as well as its precise functions in ARD pathophysiology. Here, we report the mechanisms by which ELA/APJ signaling acts in a very complex network of pathways for the maintenance of physiological functions of human tissue and organs, as well as in the onset of some ARD, where it appears to play a central role. Therefore, we describe the possibility to use the ELA/APJ pathway, as novel biomarker (predictive and diagnostic) and target for personalized treatments of ARD. Its potentiality as an optimal peptide candidate for therapeutic ARD treatments is largely described, also detailing potential current limitations.

Advances in the study of ELABELA in renal physiological functions and related diseases

ELABELA (ELA), also known as Toddler or Apela, is a novel endogenous ligand of the angiotensin receptor AT1-related receptor protein (APJ). ELA is highly expressed in human embryonic, cardiac, and renal tissues and involves various biological functions, such as embryonic development, blood circulation regulation, and maintaining body fluid homeostasis. ELA is also closely related to the occurrence and development of acute kidney injury, hypertensive kidney damage, diabetic nephropathy, renal tumors, and other diseases. Understanding the physiological role of ELA and its mechanism of action in kidney-related diseases would provide new targets and directions for the clinical treatment of kidney diseases.

Elabela inhibits TRAF1/NF-κB induced oxidative DNA damage to promote diabetic foot ulcer wound healing

Diabetic foot ulcer (DFU) is a serious complication of diabetes. Elabela (ELA), a ligand of apelin receptor (APJ), was shown to promote angiogenesis and suppress inflammation. This study aimed to illustrate the role of ELA in DFU wound healing. A whole-skin defect model was constructed using db/m and db/db mice to observe the effects of ELA on wound healing. The function of ELA in endothelial cells cultured in high glucose medium was investigated. Administration of ELA in peri-wound area of db/db mice accelerated wound closure and reduced inflammatory infiltration. Indicators of DNA damage, elevated reactive oxygen species (ROS) levels and tail DNA amounts, were downregulated by ELA but compromised after TRAF1 overexpression. ELA-mediated inhibition of NF-κB phosphorylation improved cell migration and angiogenesis, which were blocked by APJ silencing. The findings imply that ELA suppresses TRAF1-mediated NF-κB signal activation, reducing ROS-related oxidative DNA damage and improving protection of endothelial function.

High-intensity interval training induces renal injury and fibrosis in type 2 diabetic mice

AIMS

Previous studies showed that high-intensity interval training (HIIT) improved fasting blood glucose and insulin resistance in type 2 diabetes mellitus (T2DM) mice. However, the effect of HIIT on the kidneys of mice with T2DM has not been examined. This study aimed to investigate the impact of HIIT on the kidneys of T2DM mice.

MATERIALS AND METHODS

T2DM mice were induced with a high-fat diet (HFD) and one-time 100 mg/kg streptozotocin intraperitoneal injection, and then T2DM mice were treated with 8 weeks of HIIT. Renal function and glycogen deposition were observed by serum creatinine levels and PAS staining, respectively. Sirius red staining, hematoxylin-eosin staining, and Oil red O staining were used to detect fibrosis and lipid deposition. Western blotting was performed to detect the protein levels.

KEY FINDINGS

HIIT significantly ameliorated the body composition, fasting blood glucose, and serum insulin of the T2DM mice. HIIT also improved glucose tolerance, insulin tolerance, and renal lipid deposition of T2DM mice. However, we found that HIIT increased serum creatinine and glycogen accumulation in the kidneys of T2DM mice. Western blot analysis showed that the PI3K/AKT/mTOR signaling pathway was activated after HIIT. The expression of fibrosis-related proteins (TGF-β1, CTGF, collagen-III, α-SMA) increased, while the expression of klotho (sklotho) and MMP13 decreased in the kidneys of HIIT mice.

SIGNIFICANCE

This study concluded that HIIT induced renal injury and fibrosis, although it also improved glucose homeostasis in T2DM mice. The current study reminds us that patients with T2DM should be cautious when participating in HIIT.

Onchidium struma polysaccharides exhibit hypoglycemic activity and modulate the gut microbiota in mice with type 2 diabetes mellitus

Onchidium struma polysaccharides (OsPs) are natural biologically active compounds, and our previous work showed that they can inhibit the activity of α-glucosidase in vitro, showing potential hypoglycemic activity. However, the effects of OsPs on type 2 diabetes mellitus (T2DM) in vivo remain unknown. Thus, the anti-diabetic activity of OsPs was evaluated in the present study in diabetic mice. The results showed that OsPs can significantly ameliorate the features of T2DM in mice by improving the levels of fasting blood glucose (FBG), oral glucose tolerance test (OGTT), and pro-inflammatory factors, and ameliorating insulin resistance. Furthermore, OsPs can significantly improve biochemical indicators, decrease the contents of total cholesterol (TC) and triglyceride (TG), and reduce lipid accumulation in the liver. The possible mechanism of the prevention and treatment of T2DM by OsPs may involve the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT-1) signaling pathway. OsPs can regulate the dysbiosis of gut microbiota and reverse the abundance of Lactobacillus in mice with T2DM. Moreover, OsPs significantly increased the concentration of short-chain fatty acids (SCFAs) in mice with T2DM. Our results indicate that OsPs can be used as a novel food supplement for the prevention and treatment of T2DM.

Anti-apoptotic effect of HeidihuangWan in renal tubular epithelial cells via PI3K/Akt/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Heidihuang Wan (HDHW) is a classic Chinese herbal formula, which was first recorded in the "Suwen Bingji Qiyi Baoming Collection" written by Liu Wansu during the Jin Dynasty (1115-1234 AD). It is commonly used clinically for the treatment of kidney diseases and its curative effect is stable. Previous animal experiments have confirmed that HDHW can effectively improve renal fibrosis. However, the underlying pharmacological mechanism remains unclear.

AIMS OF THIS STUDY

Renal tubular epithelial cell (RTEC) apoptosis is one of the main pathological features of renal fibrosis. This study aimed to observe the effect and underlying mechanism of HDHW on the apoptosis of RTECs to further explore the pathological mechanism of HDHW against renal fibrosis.

MATERIALS AND METHODS

We examined the HDHW composition in rat serum. In vitro, we first screened out the optimal intervention concentration of HDHW on RTECs using the MTT assay. Hypoxia/reoxygenation was then used to induce apoptosis of RTECs (H/R-RTECs), which were divided into H/R-RTEC, astragaloside IV (positive control), HDHW, and RTECs groups. After 48 h of drug intervention, apoptosis of RTECs was detected using flow cytometry and protein expression was detected by western blotting. The 5/6 nephrectomy rat model was constructed and divided into the normal control, 5/6 nephrectomy, HDHW, and astragaloside IV groups. After 8 weeks of treatment, TUNEL staining was used to detect cell apoptosis, and western blotting was used to detect protein expression.

RESULTS

HDHW downregulated the expression of pro-apoptotic proteins Bax and Caspase3, up-regulated the expression of anti-apoptotic protein Bcl-2, activated the PI3K/Akt/mTOR signaling pathway, and reversed the early apoptosis of RTECs, thereby resisting the apoptosis of RTECs.

CONCLUSION

HDHW inhibits apoptosis of RTECs by modulating the PI3K/Akt/mTOR signaling pathway. This study provides experimental evidence for the anti-fibrotic effect of HDHW on the kidneys and partially elucidates its pharmacological mechanism of action.

A Novel Peptide Elabela is Associated with Hypertension-Related Subclinical Atherosclerosis

INTRODUCTION

Elabela is a newly identified peptide which, alongside apelin, acts as an endogenous ligand that activates the angiotensin receptor-like 1 receptor. Previous studies have shown the association of elabela with hypertension, but information about the role of elabela in hypertension-related subclinical atherosclerosis is scarce.

AIM

We aimed to determine the elabela levels in hypertensive patients and explore its association with subclinical atherosclerosis.

METHODS

A total of 104 subjects with hypertension were included in the study. Elabela levels were measured using an enzyme-linked immunosorbent assay, by first extracting the peptide following the manufacturer's instructions. Subclinical atherosclerosis was assessed by measuring the carotid intima-media thickness (IMT) using ultrasound.

RESULTS

Compared to stage 1, elabela levels decreased in stage 2 hypertension (0.23 [0.13, 0.45] ng/ml vs. 0.14 [0.09, 0.23] ng/ml; P = 0.000), and in the group with increased carotid IMT compared to normal IMT (0.24 [0.13, 0.38] ng/ml vs. 0.15 [0.10, 0.23] ng/ml; P = 0.005). Additionally, a linear correlation analysis showed that elabela had a significant negative correlation with systolic blood pressure (r = - 0.340, P = 0.000) and carotid IMT (r = - 0.213; P = 0.030). In multivariate analysis, lower elabela levels were associated with a higher cardiovascular risk group in this study (OR 5.0, 95% CI 1.8-13.5, P < 0.001).

CONCLUSIONS

This study demonstrated for the first time that circulating elabela declined in a higher stage of hypertension and hypertensive patients with increased carotid IMT, implicating that elabela may be involved in the pathogenesis of hypertension-associated subclinical atherosclerosis.

The Apelinergic System: Apelin, ELABELA, and APJ Action on Cell Apoptosis: Anti-Apoptotic or Pro-Apoptotic Effect?

The apelinergic system comprises two peptide ligands, apelin and ELABELA, and their cognate G-protein-coupled receptor, the apelin receptor APJ. Apelin is a peptide that was isolated from bovine stomach extracts; the distribution of the four main active forms, apelin-36, -17, -13, and pyr-apelin-13 differs between tissues. The mature form of ELABELA-32 can be transformed into forms called ELABELA-11 or -21. The biological function of the apelinergic system is multifaceted, and includes the regulation of angiogenesis, body fluid homeostasis, energy metabolism, and functioning of the cardiovascular, nervous, respiratory, digestive, and reproductive systems. This review summarises the mechanism of the apelinergic system in cell apoptosis. Depending on the cell/tissue, the apelinergic system modulates cell apoptosis by activating various signalling pathways, including phosphoinositide 3-kinase (PI3K), extracellular signal-regulated protein kinase (ERK1/2), protein kinase B (AKT), 5'AMP-activated protein kinase(AMPK), and protein kinase A (PKA). Apoptosis is critically important during various developmental processes, and any dysfunction leads to pathological conditions such as cancer, autoimmune diseases, and developmental defects. The purpose of this review is to present data that suggest a significant role of the apelinergic system as a potential agent in various therapies.

The emerging role of the apelinergic system in kidney physiology and disease

The apelinergic system (AS) is a novel pleiotropic system with an essential role in renal and cardiovascular physiology and disease, including water homeostasis and blood pressure regulation. It consists of two highly conserved peptide ligands, apelin and apela, and a G-protein-coupled apelin receptor. The two ligands have many isoforms and a short half-life and exert both similar and divergent effects. Vasopressin, apelin and their receptors colocalize in hypothalamic regions essential for body fluid homeostasis and interact at the central and renal levels to regulate water homeostasis and diuresis in inverse directions. In addition, the AS and renin-angiotensin system interact both systemically and in the kidney, with implications for the cardiovascular system. A role for the AS in diverse pathological states, including disorders of sodium and water balance, hypertension, heart failure, pre-eclampsia, acute kidney injury, sepsis and diabetic nephropathy, has recently been reported. Furthermore, several metabolically stable apelin analogues have been developed, with potential applications in diverse diseases. We review here what is currently known about the physiological functions of the AS, focusing on renal, cardiovascular and metabolic homeostasis, and the role of the AS in associated diseases. We also describe several hurdles and research opportunities worthy of the attention of the nephrology community.

Elabela Peptide: An Emerging Target in Therapeutics

Elabela, a bioactive micropeptide, is recognized as the second endogenous ligand for the Apelin receptor and is widely distributed in different tissues and organs. Elabela plays an important role in various physiological processes, such as blood pressure control, heart morphogenesis, apoptosis, angiogenesis, cell proliferation, migration, etc. Elabela is also implicated in pathological conditions, like cardiac dysfunctions, heart failure, hypertension, kidney diseases, cancer and CNS disorders. The association of Elabela with these disease conditions makes it a potential target for their therapy. This review summarizes the physiological role of Elabela peptide as well as its implication in various disease conditions.

Qishen Yiqi Dripping Pill Protects Diabetic Nephropathy by Inhibiting the PI3K-AKT Signaling Pathways in Rats

This study aimed to explore the potential mechanisms of Qishen Yiqi dripping pill (QYDP) against diabetic nephropathy (DN) through network pharmacology and animal experiments. The components and targets of QYDP and DN-related targets were retrieved from public databases. A total of 116 compounds and 160 targets of QYDP anti-DN were obtained. The top 10 hub targets including AKT1, TNF, ALB, INS, PPARG, IL-6, IL-1B, VEGF-A, JUN, and MAPK3 were screened by Cytoscape software. Then, the key targets of QYDP were enriched in 1815 Gene Ontology (GO) entries (P < 0.01) and 159 Kyoto Encyclopedia of Genomes and Genomes (KEGG) pathways (P < 0.01), mainly including the AGE-RAGE signaling pathway in diabetic complications and the PI3K-AKT signaling pathway. In animal experiments, the results of an ELISA assay showed that QYDP could regulate the expression levels of kidney function-related indexes and reduce the expression of inflammatory factors. qRT-PCR and western blot results showed that QYDP regulated the expression of hub genes. In conclusion, this study shows that QYDP could treat DN by antioxidative and antiinflammatory activity and inhibiting the PI3K-AKT signaling pathway.

Vascular Functional Effect Mechanisms of Elabela in Rat Thoracic Aorta

BACKGROUND

Elabela is a recently discovered peptide hormone. The present study aims to investigate the vasorelaxant effect mechanisms of elabela in the rat thoracic aorta.

METHODS

The vascular rings obtained from the thoracic aortas of the male Wistar Albino rats were placed in the isolated tissue bath system. Resting tension was set to 1 gram. After the equilibration period, the vessel rings were contracted with phenylephrine or potassium chloride. Once a stable contraction was achieved, elabela-32 was applied cumulatively (10^-9 - 10^-6 molar) to the vascular rings. The experimental protocol was repeated in the presence of specific signaling pathway inhibitors or potassium channel blockers to determine the effect mechanisms of elabela.

RESULTS

Elabela showed a significant vasorelaxant effect in a concentration-dependent manner (p < 0.001). The vasorelaxant effect level of elabela was significantly reduced by the apelin receptor antagonist F13A, cyclooxygenase inhibitor indomethacin, adenosine monophosphate-activated protein kinase inhibitor dorsomorphin, protein kinase C inhibitor bisindolmaleimide, large-conductance calcium-activated potassium channel blocker iberiotoxin, and intermediate-conductance calcium-activated potassium channel blocker TRAM-34 (p < 0.001). However, the vasorelaxant effect level of elabela was not significantly affected by the endothelial nitric oxide synthase inhibitor nitro-L-arginine methyl ester and mitogen-activated protein kinase inhibitor U0126.

CONCLUSIONS

Elabela exhibits a prominent vasodilator effect in rat thoracic aorta. Apelin receptor, prostanoids, adenosine monophosphate-activated protein kinase, protein kinase C, and calcium-activated potassium channels are involved in the vasorelaxant effect mechanisms of elabela.

Melatonin treatment improves human umbilical cord mesenchymal stem cell therapy in a mouse model of type II diabetes mellitus via the PI3K/AKT signaling pathway

Background

Mesenchymal stem cells (MSCs) are promising candidates for tissue regeneration and disease treatment. However, long-term in vitro passaging leads to stemness loss of MSCs, resulting in failure of MSC therapy. This study investigated whether the combination of melatonin and human umbilical cord mesenchymal stem cells (hUC-MSCs) was superior to hUC-MSCs alone in ameliorating high-fat diet and streptozocin (STZ)-induced type II diabetes mellitus (T2DM) in a mouse model.

Methods

Mice were divided into four groups: normal control (NC) group; T2DM group; hUC-MSCs treatment alone (UCMSC) group and pretreatment of hUC-MSCs with melatonin (UCMSC/Mel) group.

Results

RNA sequence analysis showed that certain pathways, including the signaling pathway involved in the regulation of cell proliferation signaling pathway, were regulated by melatonin. The blood glucose levels of the mice in the UCMSC and UCMSC/Mel treatment groups were significantly reduced compared with the T2DM group without treatment (P < 0.05). Furthermore, hUC-MSCs enhance the key factor in the activation of the PI3K/Akt pathway in T2DM mouse hepatocytes.

Conclusion

The pretreatment of hUC-MSCs with melatonin partly boosted cell efficiency and thereby alleviated impaired glycemic control and insulin resistance. This study provides a practical strategy to improve the application of hUC-MSCs in diabetes mellitus and cytotherapy.

Graphical abstract

Overview of the PI3K/AKT signaling pathway. (A) Underlying mechanism of UCMSC/Mel inhibition of hyperglycemia and insulin resistance T2DM mice via regulation of PI3K/AKT pathway. hUC-MSCs stimulates glucose uptake and improves insulin action thus should inhibition the clinical signs of T2DM, through activation of the p-PI3K/Akt signaling pathway and then regulates glucose transport through activating AS160. UCMSC/Mel increases p53-dependent expression of BCL2, and inhibit BAX and Capase3 protein activation. Leading to the decrease in apoptosis. (B) Melatonin modulated PI3K/AKT signaling pathway. Melatonin activated PI3K/AKT response pathway through binding to MT1and MT2 receptor. Leading to the increase in hUC-MSCs proliferation, migration and differentiation. → (Direct stimulatory modification); ┴ ( Direct Inhibitory modification); → ┤ (Multistep inhibitory modification); ↑ (Up regulate); ↓ (Down regulate); PI3K (Phosphoinositide 3-Kinase); AKT ( protein kinase B); PDK1 (Phosphoinositide-dependent protein kinase 1); IR, insulin receptor; GLUT4 ( glucose transporter type 4); ROS (reactive oxygen species); BCL-2 (B-cell lymphoma-2); PDK1 (phosphoinositide-dependent kinase 1) BAX (B-cell lymphoma-2-associated X protein); PCNA (Proliferating cell nuclear antigen); Cell cycle-associated proteins (KI67, cyclin A, cyclin E)

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02832-0.

Cardamomin protects from diabetes-induced kidney damage through modulating PI3K/AKT and JAK/STAT signaling pathways in rats

BACKGROUND

Diabetic nephropathy is one of the common complications of diabetes mellitus, which seriously affects the life quality and health of patients. In this study, we aimed to investigate the function of cardamonin (CAD) in diabetes-induced kidney damage in rats.

METHODS

The normal rat kidney tubular epithelial cells (NRK-52E) were pre-treated with different doses of CAD and then stimulated with methylglyoxal (MGO). Streptozotocin (STZ) induced diabetes rat model were received different doses of CAD treatment. MTT, EdU, Transwell, and flow cytometry was used to detect cell viability, proliferation, migration, and apoptosis. Western blot analysis was used to detect the expression of apoptosis related proteins, advanced glycation end-products (AGEs), receptor for AGEs (RAGE), epithelial mesenchymal transition (EMT) related proteins, phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway related proteins, and janus kinas/signal transducer and activator of transcription 3 (JAK/STAT3) related proteins. ELISA assay was used to detect the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). The levels of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) were detected using commercial kit. Hematoxylin and eosin staining was used to assess pathological changes in rat kidney.

RESULTS

Compared with control group, MGO reduced cell viability and proliferation, enhanced migration and apoptosis of NRK-52E cells, while CAD inhibited these effects induced by MGO in NRK-52E cells. Moreover, CAD increased Bcl-2 expression and decreased the expression of Bax and cleaved caspase-3 in MGO-treated NRK-52E cells. Compared with control group, MGO increased the AGEs formation, the expression of RAGE and p-p65, the levels of TNF-α, IL-6, IL-1β, MDA in NRK-52E cells and reduced the levels of GSH and SOD, while treatment of CAD dose-dependently prevented these results. In addition, CAD attenuated MGO-induced EMT of MGO-treated NRK-52E cells. Mechanically, we identified that CAD repressed PI3K/AKT and JAK/STAT3 signaling in NRK-52E cells. Importantly, the kidney injury of diabetes rats was attenuated by CAD. Besides, STZ-induced inflammatory response, oxidative stress, and phosphorylation levels of PI3K, AKT, JAK2, and STAT3 were reduced by CAD in the rats.

CONCLUSION

CAD protects from diabetes-induced kidney damage through modulating PI3K/AKT and JAK/STAT signaling pathways in rats.

Effect of Fc-Elabela-21 on renal ischemia/reperfusion injury in mice: Mediation of anti-apoptotic effect via Akt phosphorylation

INTRODUCTION

Renal ischemia/reperfusion injury (IRI) is the most common cause of acute kidney injury (AKI), and patients with AKI have a high rate of mortality. Apelin is a therapeutic candidate for treatment of IRI and Elabela (ELA) is a recently discovered hormone that also activates the apelin receptor (APJ). We examined the use of ELA as a preventive treatment for IRI using in vitro and in vivo models.

METHODS

Male mice were subjected to renal IRI, with or without administration of a stabilized form of ELA (Fc-ELA-21) for 4 days. Renal tubular lesions were measured using H&E staining, reactive oxygen species (ROS) were measured using a dihydroethidium stain assay, and renal cell apoptosis was measured using the TUNEL assay and flow cytometry. Immortalized human proximal tubular epithelial (HK-2) cells were pretreated with or without LY294002 and/or ELA-32, maintained at normoxic or hypoxic conditions, and then returned to normal culture conditions to mimic IRI. Cell apoptosis was determined using the TUNEL assay and cell proliferation was determined using the MTT assay. The levels of Akt, p-Akt, ERK1/2, p- ERK1/2, Bcl-2, Bax, caspase-3 and cleaved caspase-3 were measured using western blotting.

RESULTS

Fc-ELA-21 administration reduced renal tissue damage, ROS production, and apoptosis in mice that had renal IRI. ELA-32 reduced HK-2 cell apoptosis and restored the proliferation of cells subjected to IRI. Akt phosphorylation had a role in the anti-apoptotic effect of ELA.

CONCLUSION

This study of in vitro and in vivo models of IRI indicated that the preventive and anti-apoptotic effects of ELA were mediated via the PI3K/Akt signaling pathway.

The Role of Apelin-APJ System in Diabetes and Obesity

Nowadays, diabetes and obesity are two main health-threatening metabolic disorders in the world, which increase the risk for many chronic diseases. Apelin, a peptide hormone, exerts its effect by binding with angiotensin II protein J receptor (APJ) and is considered to be linked with diabetes and obesity. Apelin and its receptor are widely present in the body and are involved in many physiological processes, such as glucose and lipid metabolism, homeostasis, endocrine response to stress, and angiogenesis. In this review, we summarize the literatures on the role of the Apelin-APJ system in diabetes and obesity for a better understanding of the mechanism and function of apelin and its receptor in the pathophysiology of diseases that may contribute to the development of new therapies.

Sitagliptin's renoprotective effect in a diabetic nephropathy model in rats: The potential role of PI3K/AKT pathway

Management of diabetic nephropathy (DN) is far from satisfactory. There is a rising role of the involvement of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway in the pathogenesis of DN. This study aimed at investigating the renoprotective effects of PI3K/AKT pathway via sitagliptin in a rat model of DN. Thirty-two male Wistar rats were divided into four groups (eight rats each): (I) control, (II) sitagliptin, (III) DN, and (IV) DN + sitagliptin. Fasting blood glucose (FBG), kidney index, and kidney function tests in both blood and urine were measured. The levels of superoxide dismutase (SOD), tumor necrosis factor-alpha (TNF-α), and transforming growth factor-beta (TGF-β) and gene expressions of PI3K, pPI3K, AKT, and pAKT in renal tissue were detected. Renal histopathological and immunohistochemical studies were evaluated. DN + sitagliptin group showed significant decrease in FBG and kidney index, improvement in kidney function tests, and a decrease in levels of TNF-α and TGF-β in renal tissues compared with DN group. This was associated with significant increase in SOD and gene expressions of PI3K and AKT and their phosphorylated active forms in renal tissue in DN + sitagliptin group compared with DN group. Moreover, DN + sitagliptin group showed apparent decrease in amount of collagen fibers and expression of alpha-smooth muscle actin (α-SMA) compared with DN group. This work shows that sitagliptin improved renal functions and histopathological changes, impeded inflammation, and oxidative stress and upregulated PI3K/AKT pathway which highlights its renoprotective effects in a rat model of DN.

The Elabela-APJ axis: a promising therapeutic target for heart failure

Heart failure (HF) is a growing epidemic with high morbidity and mortality at an international scale. The apelin-APJ receptor pathway has been implicated in HF, making it a promising therapeutic target. APJ has been shown to be activated by a novel endogenous peptide ligand known as Elabela (ELA, also called Toddler or Apela), with a critical role in cardiac development and function. Activation of the ELA-APJ receptor axis exerts a wide range of physiological effects, including depressor response, positive inotropic action, diuresis, anti-inflammatory, anti-fibrotic, and anti-remodeling, leading to its cardiovascular protection. The ELA-APJ axis is essential for diverse biological processes and has been shown to regulate fluid homeostasis, myocardial contractility, vasodilation, angiogenesis, cellular differentiation, apoptosis, oxidative stress, cardiorenal fibrosis, and dysfunction. The beneficial effects of the ELA-APJ receptor system are well-established by treating hypertension, myocardial infarction, and HF. Additionally, administration of ELA protects human embryonic stem cells against apoptosis and stress-induced cell death and promotes survival and self-renewal in an APJ-independent manner (X receptor) via the phosphatidylinositol 3-kinase/Akt pathway, which may provide a new therapeutic approach for HF. Thus, targeting the ELA-APJ axis has emerged as a pre-warning biomarker and a novel therapeutic approach against progression of HF. An increased understanding of cardiovascular actions of ELA will help to develop effective interventions. This article gives an overview of the characteristics of the ELA-apelin-APJ axis and summarizes the current knowledge on its cardioprotective roles, potential mechanisms, and prospective application for acute and chronic HF.

The network map of Elabela signaling pathway in physiological and pathological conditions

Elabela (ELA; also called Apela and Toddler) is one of the recently discovered ligand among the two endogenous peptide ligands (Apelin and Elabela) of the apelin receptor (APLNR, also known as APJ). Elabela-induced signaling plays a crucial role in diverse biological processes, including formation of the embryonic cardiovascular system and early placental development by reducing the chances of occurrence of preeclampsia during pregnancy. It also plays the major role in the renoprotection by reducing kidney injury and the inflammatory response and regulation of gene expression associated with heart failure and fibrosis. Elabela may be processed into different active peptides, each of which binds to APLNR and predominantly activates the signals through PI3K/AKT pathway. Owing to its biomedical importance, we developed a consolidated signaling map of Elabela, in accordance with the NetPath criteria. The presented Elabela signaling map comprises 12 activation/inhibition events, 15 catalysis events, 1 molecular association, 34 gene regulation events and 32 protein expression events. The Elabela signaling pathway map is freely made available through the WikiPathways Database ( https://www.wikipathways.org/index.php/Pathway:WP5100 ).

The role of Elabela in kidney disease

Elabela, also known as Toddler or Apela, is a recently discovered hormonal peptide containing 32 amino acids. Elabela is a ligand of the apelin receptor (APJ). APJ is a G protein-coupled receptor widely expressed throughout body, and together with its cognate ligand, apelin, it plays an important role in various physiological processes including cardiovascular functions, angiogenesis and fluid homeostasis. Elabela also participates in embryonic development and pathophysiological processes in adulthood. Elabela is highly expressed in undifferentiated embryonic stem cells and regulates endoderm differentiation and cardiovascular system development. During differentiation, Elabela is highly expressed in pluripotent stem cells and in adult renal collecting ducts and loops, where it functions to maintain water and sodium homeostasis. Other studies have also shown that Elabela plays a crucial role in the pathogenesis of kidney diseases. This review addresses the role of Elabela in kidney diseases including renal ischemia/reperfusion injury, hypertensive nephropathy, diabetic nephropathy, and cardiorenal syndrome.

Lower Plasma Elabela Levels in Hypertensive Patients With Heart Failure Predict the Occurrence of Major Adverse Cardiac Events: A Preliminary Study

Background: Elabela, a novel cardiac developmental peptide, has been shown to improve heart dysfunction. However, the roles and correlation of Elabela in predicting adverse cardiac events in hypertensive patients with heart failure (HF) remain largely unclear.

Objective: To measure plasma levels of Elabela in hypertensive patients with HF and evaluate its prognostic value.

Methods: A single-site, cohort, prospective, observational study was investigated with all subjects, including control subjects and hypertensive patients with or without HF, whom were recruited in Beijing Chaoyang Hospital Affiliated to Capital Medical University form October 2018 to July 2019. The subjects among different groups were matched based on age and sex. The clinical characteristics were collected, and plasma Elabela levels were detected in all subjects. The hypertensive patients with HF were followed up for 180 days, and the major adverse cardiac events (MACE) were recorded. The Cox regression was used to explore the correlation between Elabela level and MACE in hypertensive patients with or without HF. The receiver operating characteristic curves were used to access the predictive power of plasma Elabela level.

Results: A total of 308 subjects, including 40 control subjects, 134 hypertensive patients without HF, and 134 hypertensive patients with HF were enrolled in this study. Plasma levels of Elabela were lower in hypertensive patients compared with control subjects [4.9 (2.8, 6.7) vs. 11.8 (9.8, 14.0) ng/ml, P < 0.001]. Furthermore, HF patients with preserved ejection fraction had a higher plasma Elabela level than those with impaired left ventricular systolic function (heart failure with mid-range ejection fraction and heart failure with reduced ejection fraction). The hypertensive patients with HF and higher plasma Elabela levels had a better readmission-free and MACE-free survival than those with lower plasma Elabela levels in survival analysis. The Cox regression analysis revealed that plasma Elabela levels were negatively associated with MACE (HR 0.75, 95% CI 0.61–0.99, P = 0.048) in hypertensive patients with HF.

Conclusion: Plasma Elabela levels were decreased in hypertensive patients with left ventricular systolic dysfunction. Thus, Elabela may be potentially used as a novel predictor for MACE in hypertensive patients with HF.

Elabela may regulate SIRT3-mediated inhibition of oxidative stress through Foxo3a deacetylation preventing diabetic-induced myocardial injury

Diabetic cardiomyopathy—pathophysiological heart remodelling and dysfunction that occurs in absence of coronary artery disease, hypertension and/or valvular heart disease—is a common diabetic complication. Elabela, a new peptide that acts via Apelin receptor, has similar functions as Apelin, providing beneficial effects on body fluid homeostasis, cardiovascular health and renal insufficiency, as well as potentially beneficial effects on metabolism and diabetes. In this study, Elabela treatment was found to have profound protective effects against diabetes‐induced cardiac oxidative stress, inflammation, fibrosis and apoptosis; these protective effects may depend heavily upon SIRT3‐mediated Foxo3a deacetylation. Our findings provide evidence that Elabela has cardioprotective effects for the first time in the diabetic model.

A Study on the Mechanism of Milkvetch Root in the Treatment of Diabetic Nephropathy Based on Network Pharmacology

Diabetic nephropathy (DN) is one of the most common complications of diabetes mellitus. Owing to its complicated pathogenesis, no satisfactory treatment strategies for DN are available. Milkvetch Root is a common traditional Chinese medicine (TCM) and has been extensively used to treat DN in clinical practice in China for many years. However, due to the complexity of botanical ingredients, the exact pharmacological mechanism of Milkvetch Root in treating DN has not been completely elucidated. The aim of this study was to explore the active components and potential mechanism of Milkvetch Root by using a systems pharmacology approach. First, the components and targets of Milkvetch Root were analyzed by using the Traditional Chinese Medicine Systems Pharmacology database. We found the common targets of Milkvetch Root and DN constructed a protein-protein interaction (PPI) network using STRING and screened the key targets via topological analysis. Enrichment of Gene Ontology (GO) pathways and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed. Subsequently, major hubs were identified and imported to the Database for Annotation, Visualization and Integrated Discovery for pathway enrichment analysis. The binding activity and targets of the active components of Milkvetch Root were verified by using the molecular docking software SYBYL. Finally, we found 20 active components in Milkvetch Root. Moreover, the enrichment analysis of GO and KEGG pathways suggested that AGE-RAGE signaling pathway, HIF-1 signaling pathway, PI3K-Akt signaling pathway, and TNF signaling pathway might be the key pathways for the treatment of DN; more importantly, 10 putative targets of Milkvetch Root (AKT1, VEGFA, IL-6, PPARG, CCL2, NOS3, SERPINE1, CRP, ICAM1, and SLC2A) were identified to be of great significance in regulating these biological processes and pathways. This study provides an important scientific basis for further elucidating the mechanism of Milkvetch Root in treating DN.

Circulating levels of Elabela and Apelin in the second and third trimesters of pregnancies with gestational diabetes mellitus

We design this study to detect levels of Elabela (ELA) and Apelin (APLN) in women with and without gestational diabetes mellitus (GDM) in the second and third trimesters, and to identify whether there is any association between ELA, APLN, and metabolic parameters. Seventy-nine GDM and 80 control subjects in the second trimester and 87 GDM and 88 healthy subjects in the third trimester were included. In the second trimester, lower ELA levels [(14.1 versus 16.9) ng/ml, p = .025] and higher APLN levels [(1021.8 versus 923.5) pg/ml, p = .046] were observed in GDM patients compared to controls. ELA levels were positively correlated with fasting plasma glucose (FPG) (r = 0.423, p < .001) in the control group, and APLN levels were negatively correlated with triglycerides (TG) (r = -0.251, p = .025) in the control group and total cholesterol (TC) (r = -0.227, p = .044) in the GDM group. ELA appeared to be related to glucose metabolism and APLN is involved in lipid metabolism during pregnancy. The expression of ELA is significantly downregulated from the second trimester to the third trimester.

The interaction partners of (pro)renin receptor in the distal nephron

The (pro)renin receptor (PRR), a key regulator of intrarenal renin-angiotensin system (RAS), is predominantly presented in podocytes, proximal tubules, distal convoluted tubules, and the apical membrane of collecting duct A-type intercalated cells, and plays a crucial role in hypertension, cardiovascular disease, kidney disease, and fluid homeostasis. In addition to its well-known renin-regulatory function, increasing evidence suggests PRR can also act in a variety of intracellular signaling cascades independently of RAS in the renal medulla, including Wnt/β-catenin signaling, cyclooxygenase-2 (COX-2)/prostaglandin E₂ (PGE₂ ) signaling, and the apelinergic system, and work as a component of the vacuolar H⁺ -ATPase. PRR and these pathways regulate the expression/activity of each other that controlling blood pressure and renal functions. In this review, we highlight recent findings regarding the antagonistic interaction between PRR and ELABELA/apelin, the mutually stimulatory relationship between PRR and COX-2/PGE₂ or Wnt/β-catenin signaling in the renal medulla, and their involvement in the regulation of intrarenal RAS thereby control blood pressure, renal injury, and urine concentrating ability in health and patho-physiological conditions. We also highlight the latest progress in the involvement of PRR for the vacuolar H⁺ -ATPase activity.

The Elabela in hypertension, cardiovascular disease, renal disease, and preeclampsia: an update

: Although considerable success has been shown for antihypertensive medications, the resistant hypertension and hypertension-related organ damages are still the important clinical issues and pose as high health and economic pressure. Therefore, novel therapeutic techniques and antihypertensive drugs are needed to advance more effective therapy of hypertension and hypertension-related disease to ameliorate mortality and healthcare costs worldwide. In this review, we highlight the latest progress in supporting the therapeutic potential of Elabela (ELA), a recently discovered early endogenous ligand for G-protein-coupled receptor apelin peptide jejunum, apelin receptor. Systemic administration of ELA exerts vasodilatory, antihypertensive, cardioprotective, and renoprotective effects, whereas central application of ELA increases blood pressure and causes cardiovascular remodeling primarily secondary to the hypertension. In addition, ELA drives extravillous trophoblast differentiation and prevents the pathogenesis of preeclampsia (a gestational hypertensive syndrome) by promoting placental angiogenesis. These findings strongly suggest peripheral ELA's therapeutic potential in preventing and treating hypertension and hypertension-related diseases including cardiovascular disease, kidney disease, and preeclampsia. Since therapeutic use of ELA is mainly limited by its short half-life and parenteral administration, it may be a clinical application candidate for the therapy of hypertension and its complications when fused with a large inert chemicals (e.g. polyethylene glycol, termed polyethylene glycol-ELA-21) or other proteins (e.g. the Fc fragment of IgG and albumin, termed Fc-ELA-21 or albumin-ELA-21), and new delivery methods are encouraged to develop to improve the efficacy of ELA fragments on apelin peptide jejunum or alternative unknown receptors.

Paecilomyces cicadae-fermented Radix astragali activates podocyte autophagy by attenuating PI3K/AKT/mTOR pathways to protect against diabetic nephropathy in mice

Radix astragali, a medicinal material for tonifying Chinese Qi, has widely been used for the treatment of Kidney disease in China and East Asia, especially in reducing the apoptosis of glomerular podocytes. Paecilomyces Cicadidae is a medicinal and edible fungus. In recent years, the application of traditional Chinese medicine (TCM) in solid-state fermentation of edible and medicinal fungi has become a hot issue. Fermentation is a special method to change the properties of TCM. Therefore, the potential roles and molecular mechanisms on podocytes of solid-state fermentation products of Radix astragali and Paecilomyces cicadidae (RPF) in diabetic nephropathy (DN) were studied. In vivo, the effect of RPF and Radix astragali on DN in mice was evaluated by detecting the biochemical indexes of blood and urine, renal function and podocyte integrity. In vitro, the expression of podocyte marker protein, autophagy marker protein and PI3K/AKT/mTOR signaling pathway protein were detected by Western blotting using a high glucose-induced podocyte injury model. The results showed that RPF had a significant alleviative effect on DN mice. RPF can significantly reduce urine protein, serum creatinine, and blood nitrogen urea in DN mice. Morphological analysis showed that RPF could improve kidney structure of DN and reduce the apoptosis of podocytes, and the effect was better than Radix astragali. In vitro results indicated that RPF could enhance autophagy and protect podocytes by inhibiting the PI3K/AKT/mTOR signaling pathway. In summary, RPF has better effect on delaying the development of DN than Radix astragali. RPF enhances autophagy in podocytes and delays DN probably by inhibiting the PI3K/AKT/mTOR signaling pathway.

Pathogenic Pathways and Therapeutic Approaches Targeting Inflammation in Diabetic Nephropathy

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

Exacerbated pressor and sympathoexcitatory effects of central Elabela in spontaneously hypertensive rats

Elabela (ELA) is a newly discovered peptide that acts as a novel endogenous ligand of angiotensin receptor-like 1 (APJ) receptor. This study was designed to evaluate the effects of ELA-21 in paraventricular nucleus (PVN) on blood pressure and sympathetic nerve activity in spontaneously hypertensive rats (SHR). Experiments were performed in male Wistar-Kyoto rats (WKY) and SHR. ELA expression was upregulated in PVN of SHR. PVN microinjection of ELA-21 increased renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), plasma norepinephrine, and arginine vasopressin (AVP) levels in SHR. Intravenous injection of ELA-21 significantly decreased MAP and HR in both WKY and SHR, but only induced a slight decrease in RSNA. APJ antagonist F13A in PVN abolished the effects of ELA-21 on RSNA, MAP and HR. Intravenous infusion of both ganglionic blocker hexamethonium and AVP V1a receptor antagonist SR49059 caused significant reduction in the effects of ELA-21 on RSNA, MAP and HR in SHR, while combined administration of hexamethonium and SR49059 abolished the effects of ELA-21. ELA-21 microinjection stimulated Akt and p85α subunit of phosphatidylinositol 3-kinase (PI3K) phosphorylation in PVN, whereas PI3K inhibitor LY294002 or Akt inhibitor MK-2206 almost abolished the effects of ELA-21 on RSNA, MAP, and HR. Chronic PVN infusion of ELA-21 induced sympathetic activation, hypertension, and AVP release accompanied with cardiovascular remodeling in normotensive WKY. In conclusion, ELA-21 in PVN induces exacerbated pressor and sympathoexcitatory effects in hypertensive rats via PI3K-Akt pathway.NEW & NOTEWORTHY We demonstrated that PVN microinjection of ELA-21 increases sympathetic nerve activity and blood pressure, which can be abolished by pretreatment of APJ antagonist. This is the first demonstration that central ELA can induce hypertension. The pressor effects in PVN are mediated by both sympathetic activation and vasopressin release via PI3K-Akt pathway. Our data confirm that ELA is upregulated in the PVN of SHR and so may be involved in the pressor and sympathoexcitatory effects in hypertension.

Effects of BSF on Podocyte Apoptosis via Regulating the ROS-Mediated PI3K/AKT Pathway in DN

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD). The ROS-mediated PI3K/AKT pathway plays a key role in podocyte apoptosis and DN progression. Our previous study demonstrated that Baoshenfang (BSF) can decrease proteinuria and attenuate podocyte injury. However, the effects of BSF on podocyte apoptosis induced by the ROS-mediated PI3K/AKT pathway remain unclear. Herein, in vivo and in vitro studies have been performed. In our in vivo study, BSF significantly decreased 24-h urinary protein, serum creatinine, and blood urea nitrogen levels in DN mice. Meanwhile, BSF significantly inhibited oxidative stress and podocyte apoptosis in our in vivo and in vitro studies. Moreover, BSF significantly decreased the inhibition of the PI3K/AKT pathway induced by HG in DN. More importantly, the effects of BSF on podocyte apoptosis were reversed by PI3K siRNA transfection. In conclusion, BSF can decrease proteinuria and podocyte apoptosis in DN, in part through regulating the ROS-mediated PI3K/AKT pathway.