Macrophage inflammatory protein-1β as a novel therapeutic target for renal protection in diabetic kidney disease

A Mendelian randomization study on the causal association of circulating cytokines with diabetic nephropathy

BACKGROUND

Circulating cytokines were reported to be related to diabetic nephropathy (DN) in observational studies. However, the causal relationship between them remains unknown. This study aimed to investigate the causal relationship between DN and circulating cytokines with genetic data in the frame of Mendelian Randomization (MR).

METHODS

We performed a two-sample MR analysis to investigate the causal relationship in individuals of European ancestry, utilizing publicly available genome-wide association study (GWAS) statistics. We selected eligible instrumental SNPs that were significantly related to the circulating cytokines. Multiple MR analysis approaches were employed, including inverse variance weighted (IVW), Weighted Median, MR-Egger, Weighted Mode, Simple Mode, and MR pleiotropy residual sum and outlier (MR-PRESSO) methods.

RESULTS

We found evidence supporting the causal role of genetically predicted circulating levels in the increased risk of DN. Specifically, we observed associations for interferon-gamma [OR = 1.352, 95% CI: 1.089-1.678, P = 0.006], stem cell factor [OR = 1.252, 95% CI: 1.028-1.525, P = 0.025], and stromal-cell-derived factor 1 alpha [OR = 1.326, 95% CI: 1.017-1.727, P = 0.037]. Additionally, MR analysis revealed a negative causal association between macrophage inflammatory protein 1b and DN [OR = 0.921, 95% CI: 0.858-0.988, P = 0.022]. The results obtained from MR-Egger, Weighted Median, Weighted Mode, and Simple Mode methods were consistent with the Inverse Variance Weighted (IVW) estimates. Sensitivity analyses showed no evidence of horizontal pleiotropy, suggesting that the causal estimates were not biased.

CONCLUSIONS

Our findings offer promising leads for developing novel therapeutic targets for DN. By identifying the role of inflammatory cytokines in this debilitating condition through a genetic epidemiological approach, our study made contributions to a better understanding of the underlying disease mechanisms.

Klotho antiaging protein: molecular mechanisms and therapeutic potential in diseases

Klotho, initially introduced as an anti-aging protein, is expressed in the brain, pancreas, and most prominently in the kidney. The two forms of Klotho (membrane-bound and soluble form) have diverse pharmacological functions such as anti-inflammatory, anti-oxidative, anti-fibrotic, tumour-suppressive etc. The membrane-bound form plays a pivotal role in maintaining kidney homeostasis by regulating fibroblast growth factor 23 (FGF 23) signalling, vitamin D metabolism and phosphate balance. Klotho deficiency has been linked with significantly reduced protection against various kidney pathological phenotypes, including diabetic kidney disease (DKD), which is a major cause of chronic kidney disease leading to end-stage kidney disease. Owing to the pleiotropic actions of klotho, it has shown beneficial effects in DKD by tackling the complex pathophysiology and reducing kidney inflammation, oxidative stress, as well as fibrosis. Moreover, the protective effect of klotho extends beyond DKD in other pathological conditions, including cardiovascular diseases, alzheimer's disease, cancer, inflammatory bowel disease, and liver disease. Therefore, this review summarizes the relationship between Klotho expression and various diseases with a special emphasis on DKD, the distinct mechanisms and the potential of exogenous Klotho supplementation as a therapeutic strategy. Future research into exogenous Klotho could unravel novel treatment avenues for DKD and other diseases.

Crosstalk between ferroptosis and innate immune in diabetic kidney disease: mechanisms and therapeutic implications

Diabetic kidney disease (DKD) is a prevalent complication of diabetes mellitus (DM), and its incidence is increasing alongside the number of diabetes cases. Effective treatment and long-term management of DKD present significant challenges; thus, a deeper understanding of its pathogenesis is essential to address this issue. Chronic inflammation and abnormal cell death in the kidney closely associate with DKD development. Recently, there has been considerable attention focused on immune cell infiltration into renal tissues and its inflammatory response's role in disease progression. Concurrently, ferroptosis-a novel form of cell death-has emerged as a critical factor in DKD pathogenesis, leading to increased glomerular filtration permeability, proteinuria, tubular injury, interstitial fibrosis, and other pathological processes. The cardiorenal benefits of SGLT2 inhibitors (SGLT2-i) in DKD patients have been demonstrated through numerous large clinical trials. Moreover, further exploratory experiments indicate these drugs may ameliorate serum and urinary markers of inflammation, such as TNF-α, and inhibit ferroptosis in DKD models. Consequently, investigating the interplay between ferroptosis and innate immune and inflammatory responses in DKD is essential for guiding future drug development. This review presents an overview of ferroptosis within the context of DKD, beginning with its core mechanisms and delving into its potential roles in DKD progression. We will also analyze how aberrant innate immune cells, molecules, and signaling pathways contribute to disease progression. Finally, we discuss the interactions between ferroptosis and immune responses, as well as targeted therapeutic agents, based on current evidence. By analyzing the interplay between ferroptosis and innate immunity alongside its inflammatory responses in DKD, we aim to provide insights for clinical management and drug development in this area.

Saracatinib, a Src kinase inhibitor, enhances the renoprotective effect of metformin and losartan in diabetic nephropathy

OBJECTIVE

This research assesses renoprotective effects of saracatinib (Src) in diabetic nephropathy (DN) and the potential underlying processes.

MATERIALS AND METHODS

Rats were divided into: control, DN, DN + Met + Los, DN + Met + Src, and DN + Met + Los + Src. Rats' ABP, urinary albumin, urinary nephrin, and creatinine clearance were assessed. Blood samples were collected for measuring glycaemic state parameters, renal functions, oxidative stress markers, inflammatory mediators, aldosterone, and lipid profile. Kidneys were extracted for KIM-1 and nephrin gene expression, H&E, Masson's trichrome staining, and immunohistochemical assessment.

RESULTS

Significant increases in ABP, urinary albumin and nephrin, glycaemic measurements, urea, creatinine, aldosterone, inflammatory cytokines, MDA, lipids, renal fibrosis, H scores of VEGF and TGF-β, and renal KIM-1 expression were related to DN. However, there was a significant decrease in creatinine clearance, GSH, and nephrin expression in DN group compared with control group.

DISCUSSION AND CONCLUSION

The combination of metformin (Met), losartan (Los), and Src repaired DN alterations. Adding Src to Met and Los is superior to using them alone.

Sirtuins in kidney diseases: potential mechanism and therapeutic targets

Sirtuins, which are NAD+-dependent class III histone deacetylases, are involved in various biological processes, including DNA damage repair, immune inflammation, oxidative stress, mitochondrial homeostasis, autophagy, and apoptosis. Sirtuins are essential regulators of cellular function and organismal health. Increasing evidence suggests that the development of age-related diseases, including kidney diseases, is associated with aberrant expression of sirtuins, and that regulation of sirtuins expression and activity can effectively improve kidney function and delay the progression of kidney disease. In this review, we summarise current studies highlighting the role of sirtuins in renal diseases. First, we discuss sirtuin family members and their main mechanisms of action. We then outline the possible roles of sirtuins in various cell types in kidney diseases. Finally, we summarise the compounds that activate or inhibit sirtuin activity and that consequently ameliorate renal diseases. In conclusion, targeted modulation of sirtuins is a potential therapeutic strategy for kidney diseases. Video Abstract.