Sirtuin Family and Diabetic Kidney Disease

The Clinical Role of SIRT-3 in the Acute Rejection Process of Kidney Transplantation and Its Effects on Graft Outcomes: Evaluation of Biomarker Potential

Background and Objectives: The aim of this study was to investigate the changes in the SIRT family, the effects of sirtuins on kidney graft function, and their potential as biomarkers in patients who develop rejection after kidney transplantation. Materials and Methods: Blood samples were collected from 45 kidney transplant patients before and after rejection. Some of these patients experienced T-cell-mediated early rejection (TCMR), while others presented antibody-mediated late rejection (ABMR). The mRNA expression levels of SIRT-1, SIRT-3, and SIRT-7 were measured via real-time PCR, while the protein levels of SIRT-1, SIRT-2, SIRT-3, SIRT-5, and SIRT-7 were assessed using ELISA. Patients were grouped based on rejection type and histological characteristics. Statistical analyses were performed using SPSS software (V23). Results: The mean age of the patient group was 42.22, while the control group had a mean age of 35.23 (p = 0.002). SIRT-1, SIRT-3, and SIRT-7 levels were significantly higher in patients with rejection (p < 0.001). In patients with late-stage rejection, SIRT-3 was found to be associated with interstitial fibrosis and C4d accumulation. SIRT-7 levels showed a weak correlation with potassium levels (p = 0.014). Conclusions: Our findings demonstrate significant changes in the SIRT family during both early- and late-stage rejection processes. Particularly, the role of SIRT-3 in the late stage is highlighted, suggesting the potential use of this gene as a biomarker for managing rejection processes. These findings could provide valuable insights for developing treatment strategies in organ transplantation.

Sirt6 overexpression relieves ferroptosis and delays the progression of diabetic nephropathy via Nrf2/GPX4 pathway

OBJECTIVE

Sirt6, reactive oxygen species and ferroptosis may participate in the pathogenesis of Diabetic Nephropathy (DN). Exploring the relationship between Sirt6, oxidative stress, and ferroptosis provides new scientific ideas to DN.

METHODS

Human podocytes were stimulated with 30 mM glucose and 5.5 mM glucose. The mice of db/db group were randomly divided into two groups:12 weeks and 16 weeks. Collect mouse blood and urine specimens and renal cortices for investigations. HE, Masson, PAS and immunohistochemical staining were used to observe pathological changes. Western blot, RT-qPCR and immunofluorescence staining were used to evaluate expression of relevant molecules. CCK8 method was introduced to observe cell viability. The changes of podocyte mitochondrial membrane potential and mitochondrial morphology in each group were determined by JC-1 staining and Mito-Tracker.

RESULTS

The expression level of Sirt6, Nrf2, SLC7A11, HO1, SOD2 and GPX4 were reduced, while ACSL4 was increased in DN. Blood glucose, BUN, Scr, TG, T-CHO and 24h urine protein were upregulated, while ALB was reduced in diabetic group. The treatment of Ferrostatin-1 significantly improved these changes, which proved ferroptosis was involved in the development of DN. Overexpression of Sirt6 might ameliorate the oxidation irritable reaction and ferroptosis. Sirt6 plasmid transfection increased mitochondrial membrane potential and protected morphology and structure of mitochondria. The application of Sirt6 siRNA could aggravated the damage manifestations.

CONCLUSION

High glucose stimulation could decrease the antioxidant capacity and increase formation of ROS and lipid peroxidation. Sirt6 might alleviate HG-induced mitochondrial dysfunction, podocyte injury and ferroptosis through regulating Nrf2/GPX4 pathway.

Emerging insights into the pathogenesis and therapeutic strategies for vascular endothelial injury-associated diseases: focus on mitochondrial dysfunction

As a vital component of blood vessels, endothelial cells play a key role in maintaining overall physiological function by residing between circulating blood and semi-solid tissue. Various stress stimuli can induce endothelial injury, leading to the onset of corresponding diseases in the body. In recent years, the importance of mitochondria in vascular endothelial injury has become increasingly apparent. Mitochondria, as the primary site of cellular aerobic respiration and the organelle for "energy information transfer," can detect endothelial cell damage by integrating and receiving various external stress signals. The generation of reactive oxygen species (ROS) and mitochondrial dysfunction often determine the evolution of endothelial cell injury towards necrosis or apoptosis. Therefore, mitochondria are closely associated with endothelial cell function, helping to determine the progression of clinical diseases. This article comprehensively reviews the interconnection and pathogenesis of mitochondrial-induced vascular endothelial cell injury in cardiovascular diseases, renal diseases, pulmonary-related diseases, cerebrovascular diseases, and microvascular diseases associated with diabetes. Corresponding therapeutic approaches are also provided. Additionally, strategies for using clinical drugs to treat vascular endothelial injury-based diseases are discussed, aiming to offer new insights and treatment options for the clinical diagnosis of related vascular injuries.

SIRT1: a novel regulator in colorectal cancer

The class-III histone deacetylase SIRT1 is the most extensively investigated sirtuin deacetylase. It is resistant to the broad deacetylase inhibitor trichostatin A and depends on oxidized nicotinamide adenine nucleotide (NAD+). SIRT1 plays a crucial role in the tumorigenesis of numerous types of cancers, including colorectal cancer (CRC). Accumulating evidence indicates that SIRT1 is a therapeutic target for CRC; however, the function and underlying mechanism of SIRT1 in CRC still need to be elucidated. Herein, we provide a detailed and updated review to illustrate that SIRT1 regulates many processes that go awry in CRC cells, such as apoptosis, autophagy, proliferation, migration, invasion, metastasis, oxidative stress, resistance to chemo-radio therapy, immune evasion, and metabolic reprogramming. Moreover, we closely link our review to the clinical practice of CRC treatment, summarizing the mechanisms and prospects of SIRT1 inhibitors in CRC therapy. SIRT1 inhibitors as monotherapy in CRC or in combination with chemotherapy, radiotherapy, and immune therapies are comprehensively discussed. From epigenetic regulation to its potential therapeutic effect, we hope to offer novel insights and a comprehensive understanding of SIRT1's role in CRC.

Correlation between polymorphisms of SIRT2 gene and renal injury in patients with type 2 diabetes mellitus

OBJECTIVES

Genetic factors play an important role in the pathogenesis of diabetic kidney disease (DKD). Studies have shown that SIRT2 gene polymorphism is associated with the pathogenesis of type 2 diabetes mellitus (T2DM), but its role in DKD remains unclear. This study aims to analyze the distribution of alleles and genotypes of SIRT2 gene in patients with T2DM, and investigate the association between SIRT2 genetic polymorphism and DKD susceptibility in T2DM patients, which may provide new ideas for the pathogenesis of DKD.

METHODS

A toal of 205 T2DM patients who receiving treatment in the Third Xiangya Hospital of Central South University were divided into a DKD group (n=100) and a DM group (n=105) according to the presence of kidney injury, and 100 healthy volunteers were selected as NC group. Clinical data of the subjects were collected and estimated glomerular filtration rate (eGFR) were calculated. Genomic DNA was extracted and the genotypes of single nucleotide polymorphism (SNP) loci (rs11879029, rs11879010, and rs2241703) were determined using Sanger chain termination method. The genotype/allele frequencies among the 3 groups were compared. Logistic regression was used to analyze the correlation between SNP locus genotype of SIRT2 gene and risk of DKD in T2DM patients. According to the genotypes of rs11879029/rs11879010, T2DM patients were divided into a GG1/GG2 group, a GA1/GA2 group, and an AA1/AA2 group, and the clinical data were compared. Linkage disequilibrium analysis and haplotype analysis were performed.

RESULTS

The genotype distribution and allele frequencies of the rs11879029 and rs11879010 loci in the DKD group were significantly different in comparison with the NC and DM groups (all P<0.05). For rs2241703, there were no differences in genotype and allele frequencies (all P>0.05). After correcting by age, gender, systolic blood pressure, duration of diabetes, glycosylated hemoglobin, and serum albumin, rs11879029 and rs11879010 genotype were associated with DKD susceptibility in T2DM patients. Carriers of rs11879029 genotype AA were 6.27 times more likely to have DKD than carriers of genotype GG. And carriers of rs11879010 genotype AA were 4.72 times more likely to have DKD than carriers of genotype GG. The eGFR levels in the AA1/AA2 groups were significantly lower than those in the GG1/GG2 groups (both P<0.05). Analysis of linkage disequilibrium showed complete linkage disequilibrium existed between SIRT2 rs11879029 and rs11879010, and the 2 SNPs (rs11879029 and rs11879010) were in strong linkage disequilibrium with rs2241703. Monotype GGG reduced the risk of DKD in T2DM patients (OR=0.53, 95% CI 0.35 to 0.81, P=0.003), while haplotype AAG increased the risk of DKD in patients (OR=1.80, 95% CI 1.16 to 2.80, P=0.008).

CONCLUSIONS

The genetic polymorphisms rs11879029 and rs11879010 of SIRT2 gene are potential contributors to the susceptibility of DKD in patients with T2DM, and allele A significantly increases the risk of DKD compared with allele G. The AA genotype might be a genetic risk factor for DKD.

Research progress on Sirtuins (SIRTs) family modulators

Sirtuins (SIRTs) represent a class of nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylases that exert a crucial role in cellular signal transduction and various biological processes. The mammalian sirtuins family encompasses SIRT1 to SIRT7, exhibiting therapeutic potential in counteracting cellular aging, modulating metabolism, responding to oxidative stress, inhibiting tumors, and improving cellular microenvironment. These enzymes are intricately linked to the occurrence and treatment of diverse pathological conditions, including cancer, autoimmune diseases, and cardiovascular disorders. Given the significance of histone modification in gene expression and chromatin structure, maintaining the equilibrium of the sirtuins family is imperative for disease prevention and health restoration. Mounting evidence suggests that modulators of SIRTs play a crucial role in treating various diseases and maintaining physiological balance. This review delves into the molecular structure and regulatory functions of the sirtuins family, reviews the classification and historical evolution of SIRTs modulators, offers a systematic overview of existing SIRTs modulation strategies, and elucidates the regulatory mechanisms of SIRTs modulators (agonists and inhibitors) and their clinical applications. The article concludes by summarizing the challenges encountered in SIRTs modulator research and offering insights into future research directions.

Sirt7/HIC1 complex participates in hyperglycaemia-mediated EndMT via modulation of SDC1 expression in diabetic kidney disease and metabolic memory

Diabetic kidney disease (DKD), a primary microvascular complication arising from diabetes, may result in end-stage renal disease. Epigenetic regulation of endothelial mesenchymal transition (EndMT) has been recently reported to exert function in metabolic memory and DKD. Here, we investigated the mechanism which Sirt7 modulated EndMT in human glomerular endothelial cells (HGECs) in the occurrence of metabolic memory in DKD. Lower levels of SDC1 and Sirt7 were noted in the glomeruli of both DKD patients and diabetes-induced renal injury rats, as well as in human glomerular endothelial cells (HGECs) with high blood sugar. Endothelial-to-mesenchymal transition (EndMT) was sustained despite the normalization of glycaemic control. We also found that Sirt7 overexpression associated with glucose normalization promoted the SDC1 expression and reversed EndMT in HGECs. Furthermore, the sh-Sirt7-mediated EndMT could be reversed by SDC1 overexpression. The ChIP assay revealed enrichment of Sirt7 and H3K18ac in the SDC1 promoter region. Furthermore, hypermethylated in cancer 1 (HIC1) was found to be associated with Sirt7. Overexpression of HIC1 with normoglycaemia reversed high glucose-mediated EndMT in HGECs. The knockdown of HIC1-mediated EndMT was reversed by SDC1 upregulation. In addition, the enrichment of HIC1 and Sirt7 was observed in the same promoter region of SDC1. The overexpressed Sirt7 reversed EndMT and improved renal function in insulin-treated diabetic models. This study demonstrated that the hyperglycaemia-mediated interaction between Sirt7 and HIC1 exerts a role in the metabolic memory in DKD by inactivating SDC1 transcription and mediating EndMT despite glucose normalization in HGECs.

Determinants of diabetic nephropathy among adult diabetic patients on follow-up at public hospitals in Addis Ababa, Ethiopia: A case-control study

Background

Diabetic nephropathy is defined as patients with diabetes mellitus who have persistent proteinuria for at least three consecutive measurements per year, a high blood creatinine level (>130 mol/l), or a decrease in glomerular filtration rate (<60 ml/min). Limited studies were done in Ethiopia on determinants of diabetic nephropathy among diabetic patients. Therefore, this study aimed to identify determinants of nephropathy among adult diabetic patients on follow-up at public hospitals in Addis Ababa, Ethiopia, 2022.

Methods

A hospital-based unmatched case-control study design was conducted from 6 September to 9 November 2022, among diabetic patients on follow-up at public health hospitals in Addis Ababa. Using consecutive sampling techniques, a total of 442 (353 controls and 89 cases) were recruited, with a control-to-case ratio of 4:1. The data were collected using a structured and interview-administered questionnaire and variables like high-density lipoprotein, low-density lipoprotein, Glycated hemoglobin, and type of diabetes were extracted from the medical records of the patients using a checklist. The collected data were entered into Epidata 3.1 and analyzed by STATA version 15.0. Variables with a p-value < 0.25 in the bivariable logistic regression were selected for the final model. In multivariable logistic regression model fitting, variables with a p-value < 0.05 with 95% CI adjusted odds ratio have declared statistically significant risk factors of diabetic nephropathy.

Results

In this study, out of 442 study participants, 334 controls and 89 cases were included in the analysis, with a response rate of 94.6% and 100%, respectively. The majority of the study participants were 92.13% of cases and 84.13% of controls; 7.87% of cases, and 15.87% of controls were type 2 diabetes mellitus. Age 65 and above years old (AOR: 2.42; 95% CI: 1.28, 4.57); Smoking cigarette (AOR: 2.22; 95% CI: 1.18, 4.16); Non-adherent to diet (AOR: 2.11; 95% CI: 1.15, 3.84); Drinking alcohols (AOR: 1.95; 95% CI: 1.07, 3.52); Duration with diabetes more than 10 years (AOR: 3.39; 95% CI: 1.76, 6.54); Poor glycemic control (AOR: 2.19; 95% CI: 1.23, 4.28); and Low-density lipoprotein (AOR: 2.97; 95% CI: 1.69, 5.28) were found to be statistically significant risk factors of nephropathy among diabetic patients.

Conclusion

This study found that old age, smoking cigarettes, non-adherence to diet, duration of diabetes, alcohol drinking, Glycated hemoglobin A1C, and high low-density lipoprotein were risk factors for nephropathy. Hence, continuous health education on lifestyle modifications and diabetic-related complications in each follow-up visit via front-line health professionals are very essential to avert the problem.

Emerging role and therapeutic implications of p53 in intervertebral disc degeneration

Lower back pain (LBP) is a common degenerative musculoskeletal disease that imposes a huge economic burden on both individuals and society. With the aggravation of social aging, the incidence of LBP has increased globally. Intervertebral disc degeneration (IDD) is the primary cause of LBP. Currently, IDD treatment strategies include physiotherapy, medication, and surgery; however, none can address the root cause by ending the degeneration of intervertebral discs (IVDs). However, in recent years, targeted therapy based on specific molecules has brought hope for treating IDD. The tumor suppressor gene p53 produces a transcription factor that regulates cell metabolism and survival. Recently, p53 was shown to play an important role in maintaining IVD microenvironment homeostasis by regulating IVD cell senescence, apoptosis, and metabolism by activating downstream target genes. This study reviews research progress regarding the potential role of p53 in IDD and discusses the challenges of targeting p53 in the treatment of IDD. This review will help to elucidate the pathogenesis of IDD and provide insights for the future development of precision treatments.

Oxidative stress in intervertebral disc degeneration: Molecular mechanisms, pathogenesis and treatment

Low back pain (LBP) is a leading cause of labour loss and disability worldwide, and it also imposes a severe economic burden on patients and society. Among symptomatic LBP, approximately 40% is caused by intervertebral disc degeneration (IDD). IDD is the pathological basis of many spinal degenerative diseases such as disc herniation and spinal stenosis. Currently, the therapeutic approaches for IDD mainly include conservative treatment and surgical treatment, neither of which can solve the problem from the root by terminating the degenerative process of the intervertebral disc (IVD). Therefore, further exploring the pathogenic mechanisms of IDD and adopting targeted therapeutic strategies is one of the current research hotspots. Among the complex pathophysiological processes and pathogenic mechanisms of IDD, oxidative stress is considered as the main pathogenic factor. The delicate balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining the normal function and survival of IVD cells. Excessive ROS levels can cause damage to macromolecules such as nucleic acids, lipids, and proteins of cells, affect normal cellular activities and functions, and ultimately lead to cell senescence or death. This review discusses the potential role of oxidative stress in IDD to further understand the pathophysiological processes and pathogenic mechanisms of IDD and provides potential therapeutic strategies for the treatment of IDD.

Sirtuins: Promising Therapeutic Targets to Treat Ischemic Stroke

Stroke is a major cause of mortality and disability globally, with ischemic stroke (IS) accounting for over 80% of all stroke cases. The pathological process of IS involves numerous signal molecules, among which are the highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent enzymes known as sirtuins (SIRTs). SIRTs modulate various biological processes, including cell differentiation, energy metabolism, DNA repair, inflammation, and oxidative stress. Importantly, several studies have reported a correlation between SIRTs and IS. This review introduces the general aspects of SIRTs, including their distribution, subcellular location, enzyme activity, and substrate. We also discuss their regulatory roles and potential mechanisms in IS. Finally, we describe the current therapeutic methods based on SIRTs, such as pharmacotherapy, non-pharmacological therapeutic/rehabilitative interventions, epigenetic regulators, potential molecules, and stem cell-derived exosome therapy. The data collected in this study will potentially contribute to both clinical and fundamental research on SIRTs, geared towards developing effective therapeutic candidates for future treatment of IS.

Endoplasmic reticulum stress in diabetic kidney disease: adaptation and apoptosis after three UPR pathways

Diabetes kidney disease (DKD) is one of the common chronic microvascular complications of diabetes, which has become the most important cause of modern chronic kidney disease beyond chronic glomerulonephritis. The endoplasmic reticulum is one of the largest organelles, and endoplasmic reticulum stress (ERS) is the basic mechanism of metabolic disorder in all organs and tissues. Under the stimulation of stress-induced factors, the endoplasmic reticulum, as a trophic receptor, regulates adaptive and apoptotic ERS through molecular chaperones and three unfolded protein reaction (UPR) pathways, thereby regulating diabetic renal damage. Therefore, three pathway factors have different expressions in different sections of renal tissues. This study deeply discussed the specific reagents, animals, cells, and clinical models related to ERS in DKD, and reviewed ERS-related three pathways on DKD with glomerular filtration membrane, renal tubular reabsorption, and other pathological lesions of different renal tissues, as well as the molecular biological mechanisms related to the balance of adaption and apoptosis by searching and sorting out MeSH subject words from PubMed database.

Dendrobium officinale Kimura & Migo polysaccharide inhibits hyperglycaemia-induced kidney fibrosis via the miRNA-34a-5p/SIRT1 signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Fibrosis is a fundamental change occurring in impaired renal function and plays an important role in the progression of diabetic kidney disease (DKD). Dendrobium officinale Kimura & Migo polysaccharide (DOP), a primary active component of Dendrobium officinale Kimura & Migo, is reported to act on reducing blood glucose, suppressing inflammation. However, the anti-fibrosis effect of DOP in the treatment of DKD is still unclear.

AIM OF THE STUDY

To explore the therapeutic effect of DOP on renal fibrosis in DKD.

MATERIALS AND METHODS

We used db/db mice as a DKD model and administered DOP by oral gavage. The expression of miRNA-34a-5p, SIRT1, and fibrosis molecules (TGF-β, CTGF, and a-SMA) were detected in renal tissue. Human renal tubular epithelium cells (HK-2) were cultured with 5.5 mM glucose (LG) or 25 mM glucose (HG), and intervened with 100-400 μg/ml DOP. The changes of the above indicators were observed in vitro.

RESULTS

MiRNA-34a-5p was mainly localised in the nucleus and increased expression in the DKD mice. Inhibition or excitation of miRNA-34a-5p is involved in renal fibrosis by regulating SIRT1. DOP could depress the miRNA-34a-5p/SIRT1 signalling pathway to relieve renal fibrosis. Moreover, DOP has outstanding results in the treatment of DKD through hypoglycaemic action and weight reduction.

CONCLUSIONS

DOP plays a protective role in arresting or slowing the progression of fibrosis, which may provide a novel clinical treatment strategy for DKD.

SIRT4 in ageing

Ageing is a phenomenon in which cells, tissues and organs undergo systemic pathological changes as individuals age, leading to the occurrence of ageing-related diseases and the end of life. It is associated with many phenotypes known as ageing characteristics, such as genomic instability, nutritional imbalance, mitochondrial dysfunction, cell senescence, stem cell depletion, and an altered microenvironment. The sirtuin family (SIRT), known as longevity proteins, is thought to delay ageing and prolong life, and mammals, including humans, have seven family members (SIRT1-7). SIRT4 has been studied less among the sirtuin family thus far, but it has been reported that it has important physiological functions in organisms, such as promoting DNA damage repair, participating in the energy metabolism of three substances, inhibiting inflammatory reactions and apoptosis, and regulating mitochondrial function. Recently, some studies have demonstrated the involvement of SIRT4 in age-related processes, but knowledge in this field is still scarce. Therefore, this review aims to analyse the relationship between SIRT4 and ageing characteristics as well as some age-related diseases (e.g., cardiovascular diseases, metabolic diseases, neurodegenerative diseases and cancer).

Oxidative stress as a culprit in diabetic kidney disease

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease (ESRD), and the prevalence of DKD has increased worldwide during recent years. DKD is associated with poor therapeutic outcomes in most patients, but there is limited understanding of its pathogenesis. This review suggests that oxidative stress interacts with many other factors in causing DKD. Highly active mitochondria and NAD(P)H oxidase are major sources of oxidants, and they significantly affect the risk for DKD. Oxidative stress and inflammation may be considered reciprocal causes of DKD, in that each is a cause and an effect of DKD. Reactive oxygen species (ROS) can act as second messengers in various signaling pathways and as regulators of metabolism, activation, proliferation, differentiation, and apoptosis of immune cells. Epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs can modulate oxidative stress. The development of new technologies and identification of new epigenetic mechanisms may provide novel opportunities for the diagnosis and treatment of DKD. Clinical trials demonstrated that novel therapies which reduce oxidative stress can slow the progression of DKD. These therapies include the NRF2 activator bardoxolone methyl, new blood glucose-lowering drugs such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists. Future studies should focus on improving early diagnosis and the development of more effective combination treatments for this multifactorial disease.