AGE/RAGE signaling-mediated endoplasmic reticulum stress and future prospects in non-coding RNA therapeutics for diabetic nephropathy

Mitigation of ROS-triggered endoplasmic reticulum stress by upregulating Nrf2 retards diabetic nephropathy

Endoplasmic reticulum stress (ERS) plays a crucial role in the pathogenesis of diabetic nephropathy (DN), and it is often accompanied by an increase in reactive oxygen species (ROS) production. However, the precise relationship between NFE2-related factor-2 (Nrf2), a key regulator of ROS balance, and ERS in DN remains elusive. This study aimed to investigate the impact of Nrf2 on ERS and its therapeutic potential in DN. Herein, ERS-related changes, including increased activating transcription factor-6 (ATF6), glucose-regulated protein 78 (GRP78), and transcription factor C/EBP homologous protein (CHOP) expression, were observed in the renal tissues of streptozotocin-induced DN mice and high glucose cultured human renal proximal tubular (HK-2) cells. Nrf2 knockdown increased the sensitivity of HK-2 cells to ERS under high glucose conditions, underscoring the regulatory role of Nrf2 in ERS modulation. Notably, upregulating Nrf2 in ezetimibe-treated diabetic mice restored ERS markers and ameliorated albuminuria, glomerular hypertrophy, mesangial expansion, and tubulointerstitial fibrosis. Furthermore, the inhibition of ERS in HK-2 cells by the ROS scavenger, N-acetylcysteine, highlights the interplay between ROS and ERS. This study, for the first time, elucidates that the upregulation of Nrf2 may alleviate the negative influence of ROS-mediated ERS, presenting a promising therapeutic avenue for delaying the progression of DN. These findings suggest a potential strategy for targeting Nrf2 and ERS in developing novel therapeutic interventions for DN.

Emerging insights into the role of NLRP3 inflammasome and endoplasmic reticulum stress in renal diseases

NLRP3 inflammasome is a key component of the innate immune system, mediating the activation of caspase-1, and the maturity and secretion of the pro-inflammatory cytokine interleukin (IL)-1beta (IL-1β) and IL-18 to cope with microbial infections and cell injury. The NLRP3 inflammasome is activated by various endogenous danger signals, microorganisms and environmental stimuli, including urate, extracellular adenosine triphosphate (ATP) and cholesterol crystals. Increasing evidence indicates that the abnormal activation of NLRP3 is involved in multiple diseases including renal diseases. Hence, clarifying the mechanism of action of NLRP3 inflammasome in different diseases can help prevent and treat various diseases. Endoplasmic reticulum (ER) is an important organelle which participates in cell homeostasis maintenance and protein quality control. The unfolded protein response (UPR) and ER stress are caused by the excessive accumulation of unfolded or misfolded proteins in ER to recover ER homeostasis. Many factors can cause ER stress, including inflammation, hypoxia, environmental toxins, viral infections, glucose deficiency, changes in Ca2+ level and oxidative stress. The dysfunction of ER stress participates in multiple diseases, such as renal diseases. Many previous studies have shown that NLRP3 inflammasome and ER stress play an important role in renal diseases. However, the relevant mechanisms are not yet fully clear. Herein, we focus on the current understanding of the role and mechanism of ER stress and NLRP3 inflammasome in renal diseases, hoping to provide theoretical references for future related researches.

Oxidative stress, defective proteostasis and immunometabolic complications in critically ill patients

Oxidative stress (OS) develops in critically ill patients as a metabolic consequence of the immunoinflammatory and degenerative processes of the tissues. These induce increased and/or dysregulated fluxes of reactive species enhancing their pro-oxidant activity and toxicity. At the same time, OS sustains its own inflammatory and immunometabolic pathogenesis, leading to a pervasive and vitious cycle of events that contribute to defective immunity, organ dysfunction and poor prognosis. Protein damage is a key player of these OS effects; it generates increased levels of protein oxidation products and misfolded proteins in both the cellular and extracellular environment, and contributes to forms DAMPs and other proteinaceous material to be removed by endocytosis and proteostasis processes of different cell types, as endothelial cells, tissue resident monocytes-macrophages and peripheral immune cells. An excess of OS and protein damage in critical illness can overwhelm such cellular processes ultimately interfering with systemic proteostasis, and consequently with innate immunity and cell death pathways of the tissues thus sustaining organ dysfunction mechanisms. Extracorporeal therapies based on biocompatible/bioactive membranes and new adsorption techniques may hold some potential in reducing the impact of OS on the defective proteostasis of patients with critical illness. These can help neutralizing reactive and toxic species, also removing solutes in a wide spectrum of molecular weights thus improving proteostasis and its immunometabolic corelates. Pharmacological therapy is also moving steps forward which could help to enhance the efficacy of extracorporeal treatments. This narrative review article explores the aspects behind the origin and pathogenic role of OS in intensive care and critically ill patients, with a focus on protein damage as a cause of impaired systemic proteostasis and immune dysfunction in critical illness.

Effective constituents and protective effect of Mudan granules against Schwann cell injury

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Mudan granules (MD) is a Chinese patent medicine for treating DPN, which is composed of nine Chinese medicinal herbs, including the radix of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao or Astragalus membranaceus (Fisch.) Bge. (Huangqi in Chinese), rhizome of Corydalis yanhusuo W.T. Wang (Yanhusuo), radix and rhizome of Panax notoginseng (Burk.) F. H. Chen (Sanqi), radix of Paeonia lactiflora Pall. or Paeonia veitchii Lynch (Chishao), radix and rhizome of Salvia miltiorrhiza Bge. (Danshen), rhizome of Ligusticum chuanxiong Hort. (Chuanxiong), flowers of Carthamus tinctorius L. (Honghua), lignum of Caesalpinia sappan L. (Sumu), and caulis of Spatholobus suberectus Dunn (Jixueteng). MD was reported to have a protective effect on Schwann cell (SC) that is considered as an important therapeutic target of DPN. However, the constituents of MD have not been reported, and the effective constituents and protective pathways for MD against SC injury remain unclear.

AIM OF THE STUDY

This study aimed to identify the constituents in MD, and to investigate the effective constituents and protective pathways of MD against high-glucose/lipid injury in SC.

MATERIALS AND METHODS

The chemical constituents of MD were identified using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). Protective effect and effective constituents screening were performed in an in vitro SC injury model induced by high glucose and lipid levels. The protective pathways of MD and its effective constituents were investigated by western blotting assay of related proteins.

RESULTS

A total of 136 constituents were identified in MD. MD downregulated the phosphorylation of extracellular-regulated protein kinases 1/2 (ERK1/2) and expression of cyclooxygenase-2 (COX-2) and upregulated the expression of sirtuin 2 (SIRT2). Seven effective constituents were screened out, including three from Sanqi [20(R)-ginsenoside Rh2, 20(S)-ginsenoside Rh2, and ginsenoside Rk3], one from Huangqi (astragaloside II), one from Danshen (danshensu), and two from Chuanxiong (chlorogenic and cryptochlorogenic acid). Six of the seven compounds, excluding danshensu, inhibited the phosphorylation of ERK1/2. Both astragaloside II and chlorogenic acid upregulated the expression of SIRT2, and cryptochlorogenic acid and danshensu downregulated the expression of COX-2.

CONCLUSIONS

The constituents of MD were firstly identified, and seven effective constituents were found. MD can protect SC against high-glucose and -lipid injury by downregulating ERK1/2 phosphorylation and COX-2 expression and upregulating SIRT2 expression. Seven effective constituents regulated the expression of these proteins. This study presented an important advance toward elucidating the chemical constituents, and the effective constituents and protective pathways of MD against high-glucose/lipid injury in SC, which is very helpful for investigating the action mechanism of MD on treating DPN, and could ultimately inform the development of effective quality control procedures for MD production.

Evaluation of the effects of dietary advanced glycation end products on inflammation

Advanced glycation end products (AGEs) are a large number of heterogeneous compounds formed by the glycation of proteins, fats or nucleic acids. Endogenous AGEs have been associated with various health problems such as obesity, type 2 diabetes mellitus and cardiovascular disease. Inflammation is thought to be one of the main mechanisms in the development of these disorders. Although AGEs are produced endogenously in the body, exogenous sources such as smoking and diet also contribute to the body pool. Therefore, when the AGE pool in the body rises above physiological levels, different pathological conditions may occur through various mechanisms, especially inflammation. While the effects of endogenous AGEs on the development of inflammation have been studied relatively extensively, and current evidence indicates that dietary AGEs (dAGEs) contribute to the body's AGE pool, it is not yet known whether dAGEs have the same effect on the development of inflammation as endogenous AGEs. Therefore, this review aimed to evaluate the results of cross-sectional and intervention studies to understand whether dAGEs are associated with inflammation and, if there is an effect on inflammation, through which mechanisms this effect might occur.

The role of endoplasmic reticulum-mitochondria-associated membranes in diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide. The pathomechanisms of DKD are multifactorial, yet haemodynamic and metabolic changes in the early stages of the disease appear to predispose towards irreversible functional loss and histopathological changes. Recent studies highlight the importance of endoplasmic reticulum-mitochondria-associated membranes (ER-MAMs), structures conveying important cellular homeostatic and metabolic effects, in the pathology of DKD. Disruption of ER-MAM integrity in diabetic kidneys is associated with DKD progression, but the regulation of ER-MAMs and their pathogenic contribution remain largely unknown. Exploring the cell-specific components and dynamic changes of ER-MAMs in diabetic kidneys may lead to the identification of new approaches to detect and stratify diabetic patients with DKD. In addition, these insights may lead to novel therapeutic approaches to target and/or reverse disease progression. In this review, we discuss the association of ER-MAMs with key pathomechanisms driving DKD such as insulin resistance, dyslipidaemia, ER stress, and inflammasome activation and the importance of further exploration of ER-MAMs as diagnostic and therapeutic targets in DKD.

Uncovering chemical profiles, biological potentials, and protection effect against ECM destruction in H2 O2 -treated HDF cells of the extracts of Stachys tundjeliensis

The genus Stachys L., one of the largest genera of the Lamiaceae family, is highly represented in Turkey. This study was conducted to determine the bio-pharmaceutical potential and phenolic contents of six different extracts from aerial parts of Stachys tundjeliensis. The obtained results showed that the ethanol extract exhibited the highest antioxidant activity in the antioxidant assays. Meanwhile, the ethanol extract displayed strong inhibitory activity against α-tyrosinase, the dichloromethane extract exhibited potent inhibition against butyrylcholinesterase, and the n-hexane extract against α-amylase. Based on ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry analysis, more than 90 secondary metabolites, including hydroxybenzoic acid, hydroxycinnamic acid, and their glycosides, acylquinic acids, phenylethanoid glycosides, and various flavonoids were identified or tentatively annotated in the studied S. tundjeliensis extracts. It was observed that the application of S. tundjeliensis eliminated H2 O2 -induced oxidative stress. It was determined that protein levels of phospho-nuclear factor kappa B (NF-κB), receptor for advanced glycation endproducts, and activator protein-1, which are activated in the nucleus, decreased, and the synthesis of matrix metalloproteinase (MMP)-2 and MMP-9 also decreased to basal levels. Overall, these findings suggest that S. tundjeliensis contains diverse bioactive compounds for the development of nutraceuticals or functional foods with potent biological properties.

Cannabidiol ameliorates inflammatory response partly by AGE-RAGE pathway in diabetic mice

Cannabidiol (CBD), the most abundant nonpsychoactive constituent of Cannabis sativa plant, is a promising potential pharmacotherapy for the treatment of diabetes and associated comorbidities. Previous studies have shown the potential of CBD to prevent diabetes in mice, the precise mechanisms of action remain unclear. The purpose of this study was to explore the mechanism of CBD alleviating hyperglycemia. The results demonstrated that CBD reduced blood glucose of STZ-induced diabetic mice without causing hypoglycemia. To elucidate the possible mechanisms of CBD effect, RNA-seq analysis was performed on high glucose-induced human mesangial cells (HMCs). By cluster analysis of differential genes, the results showed that advanced glycation end products-receptor of advanced glycation endproducts (AGE-RAGE) pathway-related genes CCL2 and interleukin-1β (IL-1β) play an important role in the biological of CBD. The expression of CCL2 and IL-1β were significantly increased in HMCs. Whereas, treatment with CBD decreased the expression of CCL2 and IL-1β. In addition, CBD significantly reduced AGE-RAGE levels in high glucose-induced HMCs. Similar results were confirmed in diabetic mice. In conclusion, we discovered for the first time that CBD ameliorates hyperglycemia partly through AGE-RAGE mediated CCL2/IL-1β pathway.

Induction of Vesicular Trafficking and JNK-Mediated Apoptotic Signaling in Mononuclear Leukocytes Marks the Immuno-Proteostasis Response to Uremic Proteins

INTRODUCTION

Uremic retention solutes have been alleged to induce the apoptotic program of different cell types, including peripheral blood mononuclear leukocytes (PBL), which may contribute to uremic leukopenia and immune dysfunction.

METHODS

The molecular effects of these solutes were investigated in uremic PBL (u-PBL) and mononuclear cell lines (THP-1 and K562) exposed to the high molecular weight fraction of uremic plasma (u-HMW) prepared by in vitro ultrafiltration with 50 kDa cut-off microconcentrators.

RESULTS

u-PBL show reduced cell viability and increased apoptotic death compared to healthy control PBL (c-PBL). u-HMW induce apoptosis both in u-PBL and c-PBL, as well as in mononuclear cell lines, also stimulating cellular H2O2 formation and secretion, IRE1-α-mediated endoplasmic reticulum stress signaling, and JNK/cJun pathway activation. Also, u-HMW induce autophagy in THP-1 monocytes. u-PBL were characterized by the presence in their cellular proteome of the main proteins and carbonylation targets of u-HMW, namely albumin, transferrin, and fibrinogen, and by the increased expression of receptor for advanced glycation end-products, a scavenger receptor with promiscuous ligand binding properties involved in leukocyte activation and endocytosis.

CONCLUSIONS

Large uremic solutes induce abnormal endocytosis and terminal alteration of cellular proteostasis mechanisms in PBL, including UPR/ER stress response and autophagy, ultimately activating the JNK-mediated apoptotic signaling of these cells. These findings describe the suicidal role of immune cells in facing systemic proteostasis alterations of kidney disease patients, a process that we define as the immuno-proteostasis response of uremia.

Identification of a novel competing endogenous RNA network and candidate drugs associated with ferroptosis in aldosterone-producing adenomas

Aldosterone-producing adenoma (APA), characterized by unilaterally excessive aldosterone production, is a common cause of primary aldosteronism. Ferroptosis, a recently raised iron-dependent mode of programmed cell death, has been involved in the development and therapy of various diseases. This study obtained datasets of the mRNA and lncRNA expression profiles for APA and adjacent adrenal gland (AAG) from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and lncRNAs (DE lncRNAs) associated with ferroptosis were identified. Enrichment analyses indicated 89 ferroptosis-related DEGs were primarily enriched in ROS related processes and ferroptosis. Two physical cores, and one combined core were identified in the protein-protein interaction (PPI). DEGs and clinical traits were used in conjunction to screen eight hub genes from two hub modules and 89 DEGs. A competitive endogenous RNA (ceRNA) network was constructed via co-express analysis. Thereafter, molecular docking was used to identify potential targets. Two active compounds, QL-X-138 and MK-1775, bound to AURKA and DUOX1, respectively, with the lowest binding energies. Molecular dynamics simulation verified the stability of the two complexes. In summary, our studies identified eight hub genes and a novel ceRNA regulatory network associated with ferroptosis, wherein QL-X-138 and MK-1775 were considered to be potential drugs for treating APA.

Organosulfurs, S-allyl cysteine and N-acetyl cysteine sequester di-carbonyls and reduces carbonyl stress in HT22 cells

Diabetes, characterized by high blood glucose level, is a progressive metabolic disease that leads to serious health complications. One of the major pathological consequences associated with diabetes is the accumulation of highly reactive carbonyl compounds called advanced glycation end products (AGEs). Most of the AGEs are dicarbonyls and have the potential to covalently modify proteins especially at the lysine residues in a non-enzymatic fashion (a process termed as glycation) resulting in the functional impairment and/or toxic gain in function. Therefore, non-toxic small molecules that can inhibit glycation are of interest for the therapeutic intervention of diabetes. In the present communication, we have investigated the effect of organosulfurs (S-allyl cysteine, SAC and N-acetyl cysteine, NAC) that are major principal components of Allium sativa against the glycation of different proteins. We discovered that both SAC and NAC are potent anti-glycating agents. We also found that both SAC and NAC reduce ROS level and inhibit apoptosis caused by protein glycation.

Diabetic Nephropathy: Significance of Determining Oxidative Stress and Opportunities for Antioxidant Therapies

Diabetes mellitus (DM) belongs to the category of socially significant diseases with epidemic rates of increases in prevalence. Diabetic nephropathy (DN) is a specific kind of kidney damage that occurs in 40% of patients with DM and is considered a serious complication of DM. Most modern methods for treatments aimed at slowing down the progression of DN have side effects and do not produce unambiguous positive results in the long term. This fact has encouraged researchers to search for additional or alternative treatment methods. Hyperglycemia has a negative effect on renal structures due to a number of factors, including the activation of the polyol and hexosamine glucose metabolism pathways, the activation of the renin-angiotensin-aldosterone and sympathetic nervous systems, the accumulation of advanced glycation end products and increases in the insulin resistance and endothelial dysfunction of tissues. The above mechanisms cause the development of oxidative stress (OS) reactions and mitochondrial dysfunction, which in turn contribute to the development and progression of DN. Modern antioxidant therapies for DN involve various phytochemicals (food antioxidants, resveratrol, curcumin, alpha-lipoic acid preparations, etc.), which are widely used not only for the treatment of diabetes but also other systemic diseases. It has also been suggested that therapeutic approaches that target the source of reactive oxygen species in DN may have certain advantages in terms of nephroprotection from OS. This review describes the significance of studies on OS biomarkers in the pathogenesis of DN and analyzes various approaches to reducing the intensity of OS in the prevention and treatment of DN.

Endoplasmic reticulum homeostasis: a potential target for diabetic nephropathy

The endoplasmic reticulum (ER) is the most vigorous organelle in intracellular metabolism and is involved in physiological processes such as protein and lipid synthesis and calcium ion transport. Recently, the abnormal function of the ER has also been reported to be involved in the progression of kidney disease, especially in diabetic nephropathy (DN). Here, we reviewed the function of the ER and summarized the regulation of homeostasis through the UPR and ER-phagy. Then, we also reviewed the role of abnormal ER homeostasis in residential renal cells in DN. Finally, some ER stress activators and inhibitors were also summarized, and the possibility of maintaining ER homeostasis as a potential therapeutic target for DN was discussed.

Phytochemical profile and antioxidant capacity, α-amylase and α-glucosidase inhibitory activities of Oxalis pes-caprae extracts in alloxan-induced diabetic mice

Diabetes and its complications are closely correlated with chronic hyperglycemia, causing severe oxidative stress and leading to glycation reaction with formation of advanced glycation end products. However, medicinal plants are still a source of inspiration for the discovery of new treatments of several diseases, including diabetes. The present study was aimed to evaluate the antioxidant and antidiabetic properties of Oxalis pes-caprae flowers extract in alloxan-induced diabetic mice. The phytochemical and antioxidant activities of both aqueous and methanolic extracts were assessed by in-vitro testing such as free radical scavenging assays (DPPH and ABTS⁺), ferrous ions (Fe²⁺) chelating activity and reducing power assay. Additionally, the detection of Amadori products and advanced glycation end products was used to determine the antiglycation potential. α-glucosidase and α-amylase inhibitory assessment was employed to determine the antidiabetic effect, while alloxan-induced diabetic mice were used to measure the in-vivo activities of antioxidants and carbohydrates enzymes. The effect of the methanolic extract on body weight and blood glucose level of extract-treated diabetic mice were also investigated. Among the tested extract, the methanolic extract was the richest in phenolic compounds which is directly related with their remarkable antioxidant, enzyme inhibitory and antiglycation activity. The oral administration of the two doses of Oxalis pes-caprae flowers (150 mg/kg and 250 mg/kg) daily for 3 weeks resulted in hypoglycemic effect compared to the reference drug, glibenclamide (10 mg/kg). Furthermore, the extract was shown to significantly increase the activities of antioxidants and glycolysis enzymes in the liver, kidney and spleen of diabetic mice, compared to diabetic control group. Therefore, Oxalis pes-caprae extract effectively exhibited hypoglycemic and antidiabetic effects as indicated by in-vitro and in-vivo studies, confirming the protective effects on hyperglycemia and oxidative damage.

Dysregulation of Long Noncoding RNA NEAT1/miR-199a-5/BiP Axis in Patients with Diabetic Neuropathy

OBJECTIVE

Diabetic neuropathy (DN) is a type of nerve damage and the most common complication of diabetes. Regarding the association between endoplasmic reticulum (ER) stress with the pathogenesis of neuropathy, this study aims to examine binding immunoglobulin protein (BiP) gene expression and long noncoding RNA nuclear enriched abundant transcript 1 (NEAT1), miR-199a-5 as its regulator in the peripheral blood of DN patients compared to diabetic patients without neuropathy.

METHODS

Peripheral blood samples were obtained from DN (n = 20) patients and diabetic patients without neuropathy (non-DN) (n = 20). After RNA extraction from peripheral blood mononuclear cells, reverse transcription-quantitative polymerase chain reaction was performed to evaluate RNA expression.

RESULTS

The results showed that the expression level of NEAT1 and BiP genes in the DN group increased significantly compared to the non-DN group. Also, the expression level of miR-199a-5p in the DN group was significantly downregulated.

CONCLUSION

As a result, the axis of NEAT1, miR-199a-5p, and BiP may have a role in the DN pathogenesis.

Therapeutic potential of artemisinin and its derivatives in managing kidney diseases

Artemisinin, an antimalarial traditional Chinese herb, is isolated from Artemisia annua. L, and has shown fewer side effects. Several pieces of evidence have demonstrated that artemisinin and its derivatives exhibited therapeutic effects on diseases like malaria, cancer, immune disorders, and inflammatory diseases. Additionally, the antimalarial drugs demonstrated antioxidant and anti-inflammatory activities, regulating the immune system and autophagy and modulating glycolipid metabolism properties, suggesting an alternative for managing kidney disease. This review assessed the pharmacological activities of artemisinin. It summarized the critical outcomes and probable mechanism of artemisinins in treating kidney diseases, including inflammatory, oxidative stress, autophagy, mitochondrial homeostasis, endoplasmic reticulum stress, glycolipid metabolism, insulin resistance, diabetic nephropathy, lupus nephritis, membranous nephropathy, IgA nephropathy, and acute kidney injury, suggesting the therapeutic potential of artemisinin and its derivatives in managing kidney diseases, especially the podocyte-associated kidney diseases.

Niaoduqing alleviates podocyte injury in high glucose model via regulating multiple targets and AGE/RAGE pathway: Network pharmacology and experimental validation

Purpose: The aim of present study was to explore the pharmacological mechanisms of Niaoduqing granules on the treatment of podocyte injury in diabetic nephropathy (DN) via network pharmacology and experimental validation. Methods: Active ingredients and related targets of Niaoduqing, as well as related genes of podocyte injury, proteinuria and DN, were obtained from public databases. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein-protein interaction (PPI) network analysis were performed to investigate the potential mechanisms. High glucose (HG) -induced MPC5 cell injury model was treated with the major core active ingredients of Niaoduqing and used to validate the predicted targets and signaling pathways. Results: Totally, 16 potential therapeutic targets were identified by intersecting the targets of Niaoduqing and disease, in which 7 of them were considered as the core targets via PPI network analysis. KEGG enrichment analysis showed that AGE-RAGE signaling pathway was identified as the most crucial signaling pathway. The results of in vitro experiments revealed that the treatment of Niaoduqing active ingredients significantly protected MPC5 cells from HG-induced apoptosis. Moreover, Niaoduqing could significantly attenuate the HG-induced activation of AGE-RAGE signaling pathway, whereas inhibited the over-expression of VEGF-A, ICAM-1, PTGS-2 and ACE in HG-induced MPC5 cells. Conclusion: Niaoduqing might protect against podocyte injury in DN through regulating the activity of AGE/RAGE pathway and expression of multiple genes. Further clinical and animal experimental studies are necessary to confirm present findings.

Association between diabetes and cancer. Current mechanistic insights into the association and future challenges

Compelling pieces of epidemiological, clinical, and experimental research have demonstrated that Diabetes mellitus (DM) is a major risk factor associated with increased cancer incidence and mortality in many human neoplasms. In the pathophysiology context of DM, many of the main classical actors are relevant elements that can fuel the different steps of the carcinogenesis process. Hyperglycemia, hyperinsulinemia, metabolic inflammation, and dyslipidemia are among the classic contributors to this association. Furthermore, new emerging actors have received particular attention in the last few years, and compelling data support that the microbiome, the epigenetic changes, the reticulum endoplasmic stress, and the increased glycolytic influx also play important roles in promoting the development of many cancer types. The arsenal of glucose-lowering therapeutic agents used for treating diabetes is wide and diverse, and a growing body of data raised during the last two decades has tried to clarify the contribution of therapeutic agents to this association. However, this research area remains controversial, because some anti-diabetic drugs are now considered as either promotors or protecting elements. In the present review, we intend to highlight the compelling epidemiological shreds of evidence that support this association, as well as the mechanistic contributions of many of these potential pathological mechanisms, some controversial points as well as future challenges.

Coexpression network analysis of human candida infection reveals key modules and hub genes responsible for host-pathogen interactions

Invasive fungal infections are a significant reason for morbidity and mortality among organ transplant recipients. Therefore, it is critical to investigate the host and candida niches to understand the epidemiology of fungal infections in transplantation. Candida albicans is an opportunistic fungal pathogen that causes fatal invasive mucosal infections, particularly in solid organ transplant patients. Therefore, identifying and characterizing these genes would play a vital role in understanding the complex regulation of host-pathogen interactions. Using 32 RNA-sequencing samples of human cells infected with C. albicans, we developed WGCNA coexpression networks and performed DESeq2 differential gene expression analysis to identify the genes that positively correlate with human candida infection. Using hierarchical clustering, we identified 5 distinct modules. We studied the inter- and intramodular gene network properties in the context of sample status traits and identified the highly enriched genes in the correlated modules. We identified 52 genes that were common in the most significant WGCNA turquoise module and differentially expressed genes in human endothelial cells (HUVEC) infection vs. control samples. As a validation step, we identified the differentially expressed genes from the independent Candida-infected human oral keratinocytes (OKF6) samples and validated 30 of the 52 common genes. We then performed the functional enrichment analysis using KEGG and GO. Finally, we performed protein-protein interaction (PPI) analysis using STRING and CytoHubba from 30 validated genes. We identified 8 hub genes (JUN, ATF3, VEGFA, SLC2A1, HK2, PTGS2, PFKFB3, and KLF6) that were enriched in response to hypoxia, angiogenesis, vasculogenesis, hypoxia-induced signaling, cancer, diabetes, and transplant-related disease pathways. The discovery of genes and functional pathways related to the immune system and gene coexpression and differential gene expression analyses may serve as novel diagnostic markers and potential therapeutic targets.

L-Lysine Ameliorates Diabetic Nephropathy in Rats with Streptozotocin-Induced Diabetes Mellitus

Introduction

Diabetic nephropathy is one of the leading causes of end-stage renal disease worldwide. Uncontrolled hyperglycemia and subsequent production of glycation end-products activate the paths which lead to diabetic nephropathy. The aim of this study was to assess the effects of L-lysine on antioxidant capacity, biochemical factors, kidney function, HSP70 level, and the expression of the TGFβ, VEGF, and RAGE genes in rats with streptozocin-induced diabetes mellitus.

Methods

Thirty-two male Wistar rats were randomly allocated to four eight-rat groups, namely, a healthy group, a diabetic group treated with vehicle (DM + vehicle), a diabetic group treated with L-lysine (DM + Lys), and a healthy group treated with L-lysine (healthy + Lys). Rats in the DM + Lys and the healthy + Lys groups were treated with L-lysine 0.15%. The levels of fasting blood glucose, insulin, HbA_1C, advanced glycation end-products (AGEs), lipid profile, serum creatinine, blood urea nitrogen, glomerular filtration rate, urine microalbumin, oxidative stress parameters, kidney histology and morphology, and TGFβ, VEGF, and RAGE gene expressions were assessed. Findings. An eight-week treatment with L-lysine significantly reduced the levels of fasting blood glucose, AGEs, kidney function parameters, oxidative stress parameters, lipid profile, and the TGFβ, VEGF, and RAGE gene expression and significantly increased the levels of serum insulin and tissue HSP70.

Conclusion

Treatment with L-lysine seems to slow down the progression of diabetic nephropathy.

XBP1 impacts lung adenocarcinoma progression by promoting plasma cell adaptation to the tumor microenvironment

Background: The activation of X-box binding protein 1 (XBP1) plays an essential role in the unfolded protein response (UPR) of the endoplasmic reticulum (ER). XBP1 is commonly expressed in various tumors and is closely related to tumorigenesis and progression. However, the role of XBP1 in lung adenocarcinoma (LUAD), especially the prognostic value of its alternative splicing isoforms, remains largely unknown.

Methods: The LUAD datasets were retrieved from the The Cancer Genome Atlas, ArrayExpress and Gene Expression Omnibus. GEPIA2 and meta-analysis were employed to explore the prognostic value, and bioinformatics analysis with the TIMER2.0 database was used to investigate immune cell infiltration. We performed single-cell analyses to identify cell types with high XBP1 expression. In addition, polymerase chain reaction (PCR) and DNA sequencing were performed to verify the authenticity of the new spliceosome.

Results: In this study, we found that high expression of XBP1 was significantly associated with a good prognosis, and XBP1 expression was significantly positively correlated with B cell infiltration in LUAD. In addition, we found that high-level expression of a novel splicing isoform, XBP1 (XBP1-003), improved the prognosis of LUAD. Protein structural analysis demonstrated that XBP1-003 has several specific protein domains that are different from those of other XBP1 isoforms, indicating a unique function of this isoform in LUAD.

Conclusion: All these results suggest that XBP1 plays an antitumorigenic role in LUAD through alternative splicing, which may be related to the adaptation of plasma cells. This sheds new light on the potential strategy for LUAD prognosis evaluation and immunotherapy.

The therapeutic mechanism of PuRenDan for the treatment of diabetic nephropathy: Network pharmacology and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

Purendan (PRD), as a Chinese medicinal formula, behaves remarkable therapeutic effects on diabetes and complications in clinical and experimental research. However, the underlying pharmacological mechanism in the treatment of diabetic nephropathy (DN) is still unclear.

AIMS

To investigate the therapeutical effects of PRD on DN and to explore its pharmacological mechanisms using network pharmacology and experimental verification.

MATERIALS AND METHODS

The active compounds and putative targets in PRD, and disease-related targets of DN were extracted from public databases. The key targets were identified through the protein-protein interaction (PPI) network and module analysis. The GO and KEGG enrichment analysis were performed to discover potential pharmacological mechanisms. The expression of the key targets was detected in kidney tissue in Gene Expression Omnibus (GEO) dataset. The affinity between key proteins and corresponding compounds was evaluated by molecular docking and validated by the surface plasmon resonance (SPR) assay. The indicators on major pathways and hub genes were verified by in vivo experiments.

RESULTS

In network pharmacology, 137 common targets in PRD for DN treatment were screened. The key targets and main signaling pathways including AGE-RAGE and lipid pathways were identified. The statistical difference in the expression of the key targets was verified in GSE96804 database, confirming the association with DN. The docking scores obtained from molecular docking illustrated good binding force between hub proteins and active compounds. And the good component-protein affinities were validated by SPR assay. Furthermore, the results of animal experiment indicated that PRD could ameliorate the level of serum glucose and renal function in rat model. It could regulate the expression of hub targets (AKT1, MAPK3, and STAT3) and improve indicators related with oxidative stress and lipid metabolism.

CONCLUSION

The key targets and major signaling pathways in the treatment of PRD on DN were identified. The mechanism might relate to regulation of oxidative stress and lipid metabolism.

Extracellular Vesicles Released from Stem Cells as a New Therapeutic Strategy for Primary and Secondary Glomerulonephritis

Current treatment of primary and secondary glomerulopathies is hampered by many limits and a significant proportion of these disorders still evolves towards end-stage renal disease. A possible answer to this unmet challenge could be represented by therapies with stem cells, which include a variety of progenitor cell types derived from embryonic or adult tissues. Stem cell self-renewal and multi-lineage differentiation ability explain their potential to protect and regenerate injured cells, including kidney tubular cells, podocytes and endothelial cells. In addition, a broad spectrum of anti-inflammatory and immunomodulatory actions appears to interfere with the pathogenic mechanisms of glomerulonephritis. Of note, mesenchymal stromal cells have been particularly investigated as therapy for Lupus Nephritis and Diabetic Nephropathy, whereas initial evidence suggest their beneficial effects in primary glomerulopathies such as IgA nephritis. Extracellular vesicles mediate a complex intercellular communication network, shuttling proteins, nucleic acids and other bioactive molecules from origin to target cells to modulate their functions. Stem cell-derived extracellular vesicles recapitulate beneficial cytoprotective, reparative and immunomodulatory properties of parental cells and are increasingly recognized as a cell-free alternative to stem cell-based therapies for different diseases including glomerulonephritis, also considering the low risk for potential adverse effects such as maldifferentiation and tumorigenesis. We herein summarize the renoprotective potential of therapies with stem cells and extracellular vesicles derived from progenitor cells in glomerulonephritis, with a focus on their different mechanisms of actions. Technological progress and growing knowledge are paving the way for wider clinical application of regenerative medicine to primary and secondary glomerulonephritis: this multi-level, pleiotropic therapy may open new scenarios overcoming the limits and side effects of traditional treatments, although the promising results of experimental models need to be confirmed in the clinical setting.

Analysis of Shenhuang Capsule Using HPLC: Method Development, Validation, and Application

Objective:

Shenhuang (SH) capsule is a traditional Chinese medicine compound preparation containing rhubarb, coptis, scutellaria, salvia and Pueraria, used for diabetic nephropathy studied by our research group in the early stage. This study aims to develop the method of qualitative identification and content determination of the main active ingredients of SH capsules, so as to establish the quality standard.

Methods:

HPLC method was used to determine the contents of rhein, Pueraria and tanshinone in SH capsules. The determination method of SH capsules was established through the determination of specificity, regression equation, precision, repeatability, and recovery. The general quality standard of SH capsule was established by measuring water content, disintegration time and microorganism. The contents of rhein, puerarin and tanshinone IIA in SH capsules were determined by HPLC.

Results:

The precision was 1.10–3.00%, the reproducibility and recovery rates were 95.0–105.7%. The moisture determination, disintegration time and microorganism examination of SH capsule were all in line with the standard.

Conclusion:

The stable, feasible, simple and reliable content determination method was established through the content determination of SH capsules and the general quality standard test.

Rap1a Activity Elevated the Impact of Endogenous AGEs in Diabetic Collagen to Stimulate Increased Myofibroblast Transition and Oxidative Stress

Diabetics have an increased risk for heart failure due to cardiac fibroblast functional changes occurring as a result of AGE/RAGE signaling. Advanced glycation end products (AGEs) levels are higher in diabetics and stimulate elevated RAGE (receptor for AGE) signaling. AGE/RAGE signaling can alter the expression of proteins linked to extracellular matrix (ECM) remodeling and oxidative stressors. Our lab has identified a small GTPase, Rap1a, that may overlap the AGE/RAGE signaling pathway. We sought to determine the role Rap1a plays in mediating AGE/RAGE changes and to assess the impact of isolated collagen on further altering these changes. Primary cardiac fibroblasts from non-diabetic and diabetic mice with and without RAGE expression and from mice lacking Rap1a were cultured on tail collagen extracted from non-diabetic or diabetic mice, and in addition, cells were treated with Rap1a activator, EPAC. Protein analyses were performed for changes in RAGE-associated signaling proteins (RAGE, PKC-ζ, ERK1/2) and downstream RAGE signaling outcomes (α-SMA, NF-κB, SOD-2). Increased levels of endogenous AGEs within the diabetic collagen and increased Rap1a activity promoted myofibroblast transition and oxidative stress, suggesting Rap1a activity elevated the impact of AGEs in the diabetic ECM to stimulate myofibroblast transition and oxidative stress.

The Methylglyoxal/RAGE/NOX-2 Pathway is Persistently Activated in the Hippocampus of Rats with STZ-Induced Sporadic Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia in humans, with a high social and economic cost. AD is predominantly a sporadic disease, and the intracerebroventricular (ICV) administration of streptozotocin (STZ) has been widely used as an AD-like model of dementia. While the etiology of AD remains unknown, changes such as glucose metabolism and activation of receptors for advanced glycation end products (RAGE) seem to underlie its pathogenesis. We hypothesized that methylglyoxal, an endogenous toxin derived from the glycolytic pathway, could be the precursor of advanced glycated end products that activates RAGE and that, consequently, may activate membrane NADPH oxidase (NOX), contributing to the inflammatory status of the model and the disease. We administered ICV-STZ to Wistar rats and evaluated several neurochemical parameters in the hippocampus, particularly glyoxalase 1 (GLO-1) activity, which serves as an index of high levels of methylglyoxal, and the contents of RAGE and NOX-2, the most abundant brain NOX isoform. At the times evaluated (4 and 24 weeks after STZ), we observed cognitive deficit, increased beta-amyloid content, and increased tau phosphorylation. A persistent increase in GLO-1 activity was found, as well as increases in RAGE and NOX-2 contents, suggesting astroglial and microglial commitment. The increase in NOX-2 may reflect elevated microglial activity (confirmed by IBA-1 marker), which may contribute to the synaptic dysfunction and pruning described in the literature, both in this model and AD patients. Furthermore, reinforcing this possibility, we found a reduction in cholinergic communication in the hippocampus (as shown by decreased choline acetyltransferase), a reduction in BDNF, and an increase in TGF-β, the combination of which may result in synaptic deterioration.

Lipid Droplets Protect Human β-Cells From Lipotoxicity-Induced Stress and Cell Identity Changes

Free fatty acids (FFAs) are often stored in lipid droplet (LD) depots for eventual metabolic and/or synthetic use in many cell types, such a muscle, liver, and fat. In pancreatic islets, overt LD accumulation was detected in humans but not mice. LD buildup in islets was principally observed after roughly 11 years of age, increasing throughout adulthood under physiologic conditions, and also enriched in type 2 diabetes. To obtain insight into the role of LDs in human islet β-cell function, the levels of a key LD scaffold protein, perilipin 2 (PLIN2), were manipulated by lentiviral-mediated knockdown (KD) or overexpression (OE) in EndoCβH2-Cre cells, a human cell line with adult islet β-like properties. Glucose-stimulated insulin secretion was blunted in PLIN2KD cells and improved in PLIN2OE cells. An unbiased transcriptomic analysis revealed that limiting LD formation induced effectors of endoplasmic reticulum (ER) stress that compromised the expression of critical β-cell function and identity genes. These changes were essentially reversed by PLIN2OE or using the ER stress inhibitor, tauroursodeoxycholic acid. These results strongly suggest that LDs are essential for adult human islet β-cell activity by preserving FFA homeostasis.

Impact of licochalcone A on the progression of diabetic nephropathy in type 2 diabetes mellitus of C57BL/6 mice

Diabetic nephropathy (DN) is the most common chronic microvascular complication of diabetes. Therefore, it is of great significance to effectively prevent and treat DN. Licochalcone A (LicA) is a flavonoid found in licorice; previous studies have shown that LicA can reduce blood glucose, blood lipids and improve insulin resistance. There has been no research on whether LicA can prevent and treat DN. In this study, an animal model of type 2 diabetes mellitus (T2DM) mice induced by high fat diet/streptozotocin was established, and the intervention of LicA was applied to investigate the protective effect of LicA on the kidneys of DN mice. After 4 weeks of intervention, LicA could effectively reduce blood glucose and alleviate the phenomenon of weight loss in mice. Meanwhile, the levels of MDA, SOD and GSH-Px in the kidney tissue and serum were recovered to different degrees. Besides, LicA decreased the levels of TC, TG and LDL-C in the kidney tissue and increased the level of HDL-C in the kidney tissue. The 24 h urinary protein, blood urea nitrogen (BUN) and serum creatinine (SCr) levels of mice in the treatment group of LicA were significantly lower than those in the model group. Furthermore, HE staining, PAS staining and Masson staining indicated that LicA improved the pathological damage of kidneys, and the kidney index of mice also decreased. Western blotting results indicated that LicA could significantly down-regulate the protein expression of AGEs/RAGE, TGF-β1, HIF-1α and GLUT1, and up-regulate the protein expression of Nrf2. It provides a theoretical basis for the further development and utilization of LicA.

Pentagalloylglucose reduces AGE-induced inflammation by activating Nrf2/HO-1 and inhibiting the JAK2/STAT3 pathway in mesangial cells

Pentagalloylglucose (PGG), a gallotannin polyphenolic compound, has been found to possess a host of beneficial pharmacologic activities, such as anti-inflammatory and antioxidative activities. We previously demonstrated that PGG is capable of binding to the cell membrane of renal mesangial cells, but the pharmacological effect of PGG on diabetic renal injury and the underlying mechanisms are still not yet clear. In this study, the effects of PGG on Nrf2/HO-1 and JAK2/STAT3 signaling were explored in AGE-stimulated mesangial cells. Furthermore, the Nrf2 transcriptional inhibitor ML385 was used to verify the involvement of Nrf2 in the PGG-mediated inhibition of the JAK2/STAT3 cascade. Our results showed that PGG significantly inhibited AGE-induced ROS generation and activated AGE-inhibited Nrf2/HO-1 signaling. Moreover, AGE-induced inflammatory cytokines (IL-1β and TNF-α) and their signaling through JAK2/STAT3 were blocked by PGG. Furthermore, ML385 suppressed Nrf2/HO-1 signaling, elevated ROS and cytokine production, and activated JAK2/STAT3 cascade were reversed by PGG. These findings indicate that PGG inhibits the JAK2/STAT3 cascade by activating Nrf2/HO-1 signaling.

Organelle stress and glycation in kidney disease

Glycation of proteins is a non-enzymatic posttranslational modification. Such random modification often deranges the structure and function of a wide range of proteins, and in turn leads to cellular dysfunction and organ damage. Protein glycation is thus an important topic in understanding the molecular mechanisms of the development or progression of various kinds of diabetes-related diseases. Meanwhile, organelle stress, such as mitochondrial or endoplasmic reticulum (ER) damage, is a causal factor for cellular dysfunction. Under pathogenic conditions, mitochondrial stress and ER stress are induced by glycated proteins. Intensive research has revealed the molecular mechanism of how glycation contributes to cell fate via organelle stress. This article will summarize the most recent evidence on organelle stress and glycation in kidney disease, especially diabetic kidney disease (DKD) associated with high glycation status.

Using Network Pharmacology to Explore the Mechanism of Peach Kernel-Safflower in the Treatment of Diabetic Nephropathy

OBJECTIVE

The mechanism of peach kernel-safflower in treating diabetic nephropathy (DN) was investigated using network pharmacology.

METHODS

Network pharmacology methodology was applied to screen the effective compounds of peach kernel-safflower in the SymMap and TCMSP databases. Potential targets were then screened in the ETCM, SEA, and SymMap databases to construct a compound-target network. This was followed by screening of DN targets in OMIM, Gene, and GeneCards databases. The common targets of drugs and diseases were selected for analysis in the STRING database, and the results were imported into Cytoscape 3.8.0 to construct a protein-protein interaction network. Next, GO and KEGG enrichment analyses were performed. Finally, Schrödinger molecular docking verified the reliability of the results.

RESULTS

A total of 23 effective compounds and 794 potential targets resulted from our screening process. Quercetin and luteolin were identified as the main effective ingredients in peach kernel-safflower. Furthermore, five key targets (VEGFA, IL6, TNF, AKT1, and TP53), AGE-RAGE, fluid shear stress and atherosclerosis, IL-17, and HIF-1 signaling pathways may be involved in the treatment of DN using peach kernel-safflower.

CONCLUSIONS

This study embodies the complex network relationship of multicomponents, multitargets, and multipathways of peach kernel-safflower to treat DN and provides a basis for further research on its mechanism.

Endothelial Dysfunction in Diabetes Is Aggravated by Glycated Lipoproteins; Novel Molecular Therapies

Diabetes and its vascular complications affect an increasing number of people. This disease of epidemic proportion nowadays involves abnormalities of large and small blood vessels, all commencing with alterations of the endothelial cell (EC) functions. Cardiovascular diseases are a major cause of death and disability among diabetic patients. In diabetes, EC dysfunction (ECD) is induced by the pathological increase of glucose and by the appearance of advanced glycation end products (AGE) attached to the plasma proteins, including lipoproteins. AGE proteins interact with their specific receptors on EC plasma membrane promoting activation of signaling pathways, resulting in decreased nitric oxide bioavailability, increased intracellular oxidative and inflammatory stress, causing dysfunction and finally apoptosis of EC. Irreversibly glycated lipoproteins (AGE-Lp) were proven to have an important role in accelerating atherosclerosis in diabetes. The aim of the present review is to present up-to-date information connecting hyperglycemia, ECD and two classes of glycated Lp, glycated low-density lipoproteins and glycated high-density lipoproteins, which contribute to the aggravation of diabetes complications. We will highlight the role of dyslipidemia, oxidative and inflammatory stress and epigenetic risk factors, along with the specific mechanisms connecting them, as well as the new promising therapies to alleviate ECD in diabetes.