Mycophenolate Mofetil Ameliorates Diabetic Nephropathy in db/db Mice

The mechanism of enterogenous toxin methylmalonic acid aggravating calcium-phosphorus metabolic disorder in uremic rats by regulating the Wnt/β-catenin pathway

BACKGROUND

Uremia (UR) is caused by increased UR-related toxins in the bloodstream. We explored the mechanism of enterogenous toxin methylmalonic acid (MMA) in calcium-phosphorus metabolic disorder in UR rats via the Wnt/β-catenin pathway.

METHODS

The UR rat model was established by 5/6 nephrectomy. The fecal bacteria of UR rats were transplanted into Sham rats. Sham rats were injected with exogenous MMA or Salinomycin (SAL). Pathological changes in renal/colon tissues were analyzed. MMA concentration, levels of renal function indicators, serum inflammatory factors, Ca2+/P3+, and parathyroid hormone, intestinal flora structure, fecal metabolic profile, intestinal permeability, and glomerular filtration rate (GFR) were assessed. Additionally, rat glomerular podocytes were cultured, with cell viability and apoptosis measured.

RESULTS

Intestinal flora richness and diversity in UR rats were decreased, along with unbalanced flora structure. Among the screened 133 secondary differential metabolites, the MMA concentration rose, showing the most significant difference. UR rat fecal transplantation caused elevated MMA concentration in the serum and renal tissues of Sham rats. The intestinal flora metabolite MMA or exogenous MMA promoted intestinal barrier impairment, increased intestinal permeability, induced glomerular podocyte loss, and reduced GFR, causing calcium-phosphorus metabolic disorder. The intestinal flora metabolite MMA or exogenous MMA induced inflammatory responses and facilitated glomerular podocyte apoptosis by activating the Wnt/β-catenin pathway, which could be counteracted by repressing the Wnt/β-catenin pathway.

CONCLUSIONS

Enterogenous toxin MMA impelled intestinal barrier impairment in UR rats, enhanced intestinal permeability, and activated the Wnt/β-catenin pathway to induce glomerular podocyte loss and reduce GFR, thus aggravating calcium-phosphorus metabolic disorder.

IL-17 in type II diabetes mellitus (T2DM) immunopathogenesis and complications; molecular approaches

Chronic inflammation has long been considered the characteristic feature of type II diabetes mellitus (T2DM) Immunopathogenesis. Pro-inflammatory cytokines are considered the central drivers of the inflammatory cascade leading to β-cell dysfunction and insulin resistance (IR), two major pathologic events contributing to T2DM. Analyzing the cytokine profile of T2DM patients has also introduced interleukin-17 (IL-17) as an upstream regulator of inflammation, regarding its role in inducing the nuclear factor-kappa B (NF-κB) pathway. In diabetic tissues, IL-17 induces the expression of inflammatory cytokines and chemokines. Hence, IL-17 can deteriorate insulin signaling and β-cell function by activating the JNK pathway and inducing infiltration of neutrophils into pancreatic islets, respectively. Additionally, higher levels of IL-17 expression in patients with diabetic complications compared to non-complicated individuals have also proposed a role for IL-17 in T2DM complications. Here, we highlight the role of IL-17 in the Immunopathogenesis of T2DM and corresponding pathways, recent advances in preclinical and clinical studies targeting IL-17 in T2DM, and corresponding challenges and possible solutions.

Understanding the podocyte immune responses in proteinuric kidney diseases: from pathogenesis to therapy

The glomerular filtration barrier, comprising the inner layer of capillary fenestrated endothelial cells, outermost podocytes, and the glomerular basement membrane between them, plays a pivotal role in kidney function. Podocytes, terminally differentiated epithelial cells, are challenging to regenerate once injured. They are essential for maintaining the integrity of the glomerular filtration barrier. Damage to podocytes, resulting from intrinsic or extrinsic factors, leads to proteinuria in the early stages and eventually progresses to chronic kidney disease (CKD). Immune-mediated podocyte injury is a primary pathogenic mechanism in proteinuric glomerular diseases, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and lupus nephritis with podocyte involvement. An extensive body of evidence indicates that podocytes not only contribute significantly to the maintenance of the glomerular filtration barrier and serve as targets of immune responses but also exhibit immune cell-like characteristics, participating in both innate and adaptive immunity. They play a pivotal role in mediating glomerular injury and represent potential therapeutic targets for CKD. This review aims to systematically elucidate the mechanisms of podocyte immune injury in various podocyte lesions and provide an overview of recent advances in podocyte immunotherapy. It offers valuable insights for a deeper understanding of the role of podocytes in proteinuric glomerular diseases, and the identification of new therapeutic targets, and has significant implications for the future clinical diagnosis and treatment of podocyte-related disorders.

Augmentation of Cathepsin Isoforms in Diabetic db/db Mouse Kidneys Is Associated with an Increase in Renal MARCKS Expression and Proteolysis

The expression of the myristoylated alanine-rich C-kinase substrate (MARCKS) family of proteins in the kidneys plays an important role in the regulation of the renal epithelial sodium channel (ENaC) and hence overall blood pressure regulation. The function of MARCKS is regulated by post-translational modifications including myristoylation, phosphorylation, and proteolysis. Proteases known to cleave both ENaC and MARCKS have been shown to contribute to the development of high blood pressure, or hypertension. Here, we investigated protein expression and proteolysis of MARCKS, protein expression of multiple protein kinase C (PKC) isoforms, and protein expression and activity of several different proteases in the kidneys of diabetic db/db mice compared to wild-type littermate mice. In addition, MARCKS protein expression was assessed in cultured mouse cortical collecting duct (mpkCCD) cells treated with normal glucose and high glucose concentrations. Western blot and densitometric analysis showed less abundance of the unprocessed form of MARCKS and increased expression of a proteolytically cleaved form of MARCKS in the kidneys of diabetic db/db mice compared to wild-type mice. The protein expression levels of PKC delta and PKC epsilon were increased, while cathepsin B, cathepsin S, and cathepsin D were augmented in diabetic db/db kidneys compared to those of wild-type mice. An increase in the cleaved form of MARCKS was observed in mpkCCD cells cultured in high glucose compared to normal glucose concentrations. Taken together, these results suggest that high glucose may contribute to an increase in the proteolysis of renal MARCKS, while the upregulation of the cathepsin proteolytic pathway positively correlates with increased proteolysis of MARCKS in diabetic kidneys, where PKC expression is augmented.

Identification of a novel immune landscape signature as effective diagnostic markers related to immune cell infiltration in diabetic nephropathy

Background

The study aimed to identify core biomarkers related to diagnosis and immune microenvironment regulation and explore the immune molecular mechanism of diabetic nephropathy (DN) through bioinformatics analysis.

Methods

GSE30529, GSE99325, and GSE104954 were merged with removing batch effects, and different expression genes (DEGs) were screened at a criterion |log2FC| >0.5 and adjusted P <0.05. KEGG, GO, and GSEA analyses were performed. Hub genes were screened by conducting PPI networks and calculating node genes using five algorithms with CytoHubba, followed by LASSO and ROC analysis to accurately identify diagnostic biomarkers. In addition, two different GEO datasets, GSE175759 and GSE47184, and an experiment cohort with 30 controls and 40 DN patients detected by IHC, were used to validate the biomarkers. Moreover, ssGSEA was performed to analyze the immune microenvironment in DN. Wilcoxon test and LASSO regression were used to determine the core immune signatures. The correlation between biomarkers and crucial immune signatures was calculated by Spearman analysis. Finally, cMap was used to explore potential drugs treating renal tubule injury in DN patients.

Results

A total of 509 DEGs, including 338 upregulated and 171 downregulated genes, were screened out. "chemokine signaling pathway" and "cell adhesion molecules" were enriched in both GSEA and KEGG analysis. CCR2, CX3CR1, and SELP, especially for the combination model of the three genes, were identified as core biomarkers with high diagnostic capabilities with striking AUC, sensitivity, and specificity in both merged and validated datasets and IHC validation. Immune infiltration analysis showed a notable infiltration advantage for APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. In addition, the correlation analysis showed that CCR2, CX3CR1, and SELP were strongly and positively correlated with checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. Finally, dilazep was screened out as an underlying compound for DN analyzed by CMap.

Conclusions

CCR2, CX3CR1, and SELP are underlying diagnostic biomarkers for DN, especially in their combination. APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation may participate in the occurrence and development of DN. At last, dilazep may be a promising drug for treating DN.

pre-existing diabetes and PTDM in kidney transplant recipients: how to handle immunosuppression

INTRODUCTION

Preexisting diabetes (PD) and post-transplant diabetes mellitus (PTDM) are common and severe comorbidities posttransplantation. The immunosuppressive regimens are modifiable risk factors.

AREAS COVERED

We reviewed Pubmed and Cochrane database and we summarize the mechanisms and impacts of available immunosuppressive treatments on the risk of PD and PTDM. We also assess the possible management of these drugs to improve glycemic parameters while considering risks inherent in transplantation.

EXPERT OPINION

PD i) increases the risk of sepsis, ii) is an independent risk factor for infection-related mortality, and iii) increases acute rejection risk. Regarding PTDM development i) immunosuppressive strategies without corticosteroids significantly reduce the risk but the price may be a higher incidence of rejection; ii) minimization or rapid withdrawal of steroids are two valuable approaches; iii) the diabetogenic role of calcineurin inhibitors(CNIs) is also well-described and is more important for tacrolimus than for cyclosporine. Reducing tacrolimus-exposure may improve glycemic parameters but also has a higher risk of rejection. PTDM risk is higher in patients that receive sirolimus compared to mycophenolate mofetil. Finally, conversion from CNIs to belatacept may offer the best benefits to PTDM-recipients in terms of glycemic parameters, graft and patient-outcomes.

Low vitamin D is associated with diabetes peripheral neuropathy in older but not in young and middle-aged patients

BACKGROUND

The relationship between vitamin D and diabetes peripheral neuropathy (DPN) is not consistent among epidemiologic studies. Thus, we aimed to investigate this relationship in different age groups.

METHODS

In this cross-sectional study, 1461 patients admitted to the Department of Endocrinology at Xinhua Hospital from June 2016 to September 2017 were divided into three age groups: a Youth group (24-44 years, n = 127), a Middle-age group (45-64 years, n = 779), and an Elderly group (≥65 years, n = 555). Basic information and laboratory results were collected from medical records.

RESULTS

Among the patients, 32.72% had DPN, with 12.59% in the Youth group, 33.63% in the Middle-age group, and 36.04% in the Elderly group. For the total sample and the Elderly group, serum 25(OH)D concentrations in DPN patients were lower than in non-DPN patients (P < .05). The results of multivariate logistic regression indicated a low vitamin D concentration to be a risk factor for DPN in the Elderly group (P < .05), but such relationship was not found in the Youth or Middle-age groups. Moreover, according to ROC analysis, a serum 25(OH)D level < 34.87 nmol/L suggests the occurrence of DPN in elderly patients with type 2 diabetes (P < .001).

CONCLUSIONS

This study is the first to report that a low vitamin D level is associated with DPN in diabetic patients over 65 years of age and might be used as a predictor of DPN in this population. The interaction between vitamin D and age in the development of DPN and its underlying mechanisms need to be further explored.

Shen-Kang protects against tacrolimus-induced renal injury

BACKGROUND/AIMS

Evidence suggests that Shen-Kang (SK), a traditional Chinese herbal medicine, protects against various types of renal injury. In this study, we evaluated whether SK treatment confers renoprotection in a rat model of chronic tacrolimus (TAC) nephropathy.

METHODS

Rats were treated daily with TAC (1.5mg/kg, subcutaneously) and SK (450 mg/kg, intravenously) for 4 weeks. The effects of SK on TAC-induced renal injury were assessed by measuring renal function, urine albumin excretion, histopathology, inflammatory cell infiltration, expression of profibrotic (transforming growth factor β1 [TGF-β1] and TGF-β inducible gene-h3 [βig-h3]) and proinflammatory cytokines, oxidative stress, and apoptotic cell death.

RESULTS

Administration of SK preserved glomerular integrity (fractional mesangial area and Wilms tumor 1-positive glomeruli), attenuated tubulointerstitial fibrosis, and reduced the number of ectodermal dysplasia 1-positive cells, and this was paralleled by improved urine albumin excretion and renal dysfunction. At the molecular level, SK treatment suppressed expression of TGF-β1/Smad2/3, βig-h3, and proinflammatory cytokines. Oxidative stress and apoptotic cell death were significantly decreased with SK treatment, and apoptosis-related genes were regulated toward cell survival (active caspase-3 and the B-cell lymphoma-2/Bcl2-associated X [Bcl-2/Bax] ratio).

CONCLUSION

SK protects against TAC-induced renal injury.

Unraveling the Role of Inflammation in the Pathogenesis of Diabetic Kidney Disease

Diabetic kidney disease (DKD) remains the leading cause of end-stage renal disease (ESRD) and is therefore a major burden on the healthcare system. Patients with DKD are highly susceptible to developing cardiovascular disease, which contributes to increased morbidity and mortality rates. While progress has been made to inhibit the acceleration of DKD, current standards of care reduce but do not eliminate the risk of DKD. There is growing appreciation for the role of inflammation in modulating the process of DKD. The focus of this review is on providing an overview of the current status of knowledge regarding the pathologic roles of inflammation in the development of DKD. Finally, we summarize recent therapeutic advances to prevent DKD, with a focus on the anti-inflammatory effects of newly developed agents.

FGF23C-tail improves diabetic nephropathy by attenuating renal fibrosis and inflammation

BACKGROUND

High level of serum fibroblast growth factor 23 (FGF23) is implicated in the development and progression of diabetic nephropathy (DN), making it a crucial factor in the pathogenesis of DN. FGF23 is also tightly correlated with inflammation in the progression of DN. The aim of this study was to explore whether the C-terminal of FGF23 (FGF23^C-tail), an antagonist that can block the FGF23 signaling pathway by competing with intact FGF23, could exhibit a therapeutic effect on DN.

RESULTS

Biochemical data and histological examination showed that FGF23 ^C-tail administration ameliorated the functional and morphological abnormalities of db/db mice with DN without changing the levels of circulating FGF23 and phosphate. Evaluation of morphology and fibrosis by Masson's trichrome staining and IHC staining of fibronectin, PCR, and western blot analysis showed that FGF23^C-tail prevents diabetes-induced fibrosis in db/db mice. Importantly, FGF23^C-tail decreased the levels of inflammatory cytokines in serum and renal tissues.

CONCLUSION

FGF23^C-tail may improve diabetic nephropathy by decreasing inflammation and fibrosis in db/db mice, suggesting that blocking of FGF23 action remains an important therapeutic target for the prevention or attenuation of the progression of DN.

Anti-Inflammatory Therapy Modulates Nrf2-Keap1 in Kidney from Rats with Diabetes

This study addressed the relationship of proinflammatory cytokines and Nrf2-Keap1 system in diabetic nephropathy. The experimental groups were control, diabetic, and diabetic treated with mycophenolate mofetil (MMF). The renal function, proinflammatory and profibrotic cytokines, oxidative stress, morphology, and nephrin expression were assessed. Diabetic group showed impaired renal function in association with oxidative stress and decreased Nrf2 nuclear translocation. These results were associated with increased mesangial matrix index, interstitial fibrosis, and increased nephrin expression in cortex and urine excretion. Additionally, interleukin-1β, IL-6, and transforming growth factor-β1 were increased in plasma and kidney. MMF treatment conserved renal function, prevented renal structural alterations, and partially prevented the proinflammatory and profibrotic cytokines overexpression. Despite that MMF treatment induced nephrin overexpression in renal tissue, preventing its urinary loss. MMF salutary effects were associated with a partial prevention of oxidative stress, increased Nrf2 nuclear translocation, and conservation of antioxidant enzymes in renal tissue. In conclusion, our results confirm that inflammation is a key factor in the progression of diabetic nephropathy and suggest that treatment with MMF protects the kidney by an antioxidant mechanism, possibly regulated at least in part by the Nrf2/Keap1 system, in addition to its well-known anti-inflammatory effects.