Early Diabetic Kidney Disease Research Articles

The retinal blood flow density is related to the pathological severity of diabetic kidney disease.

This study aimed to investigate the correlation between fundus blood flow parameters and the severity of pathological biopsy in patients with diabetic kidney disease (DKD). Data of patients with type 2 diabetes mellitus who completed renal pathology biopsies and optical coherence tomography angiography (OCTA) examinations, including renal function, 24-h urine protein quantification, and macular flow imaging, were collected. DKD pathology biopsies were graded as stages 1-4, and differences and correlations of the parameters were compared between groups. The grading was transformed into early (stage 1) and late (stages 2-4), and regression analyses were conducted to develop a model, draw a nomogram, and test efficacy. This study included 157 eyes from 157 individuals in total. Urinary microalbumin and to urinary creatinine ratio (mALB/NCR) increased with pathological grading, whereas while glomerular filtration rate was decreased (p < 0.01). Corresponding retinal blood flow in superficial, deep, and full paracentral rings was decreased, which correlated with pathological grading (p < 0.01), with the highest blood flow density in the whole layer (r2 = -0.707). Meaningfully, in the early DKD model (area under the curve =0.929 (0.889-0.970), p < 0.01), whole-layer blood flow density, mALB/NCR, and diabetes duration were statistically significant. The decrease in macular retinal blood flow density detected by OCTA is closely associated with the increase in pathological grading of DKD and can be used as a noninvasive parameter for monitoring early changes in DKD.

Causal relationship between gut microbiota and diabetic complications: a two-sample Mendelian randomization study

BackgroundImbalances in gut microbiota (GM) have been proposed as a potential contributing factor to diabetic complications; however, the causal relationship remains incompletely understood.MethodsSummary statistics were obtained from genome-wide association studies (GWAS) of 196 gut microbial taxa, including 9 phyla, 16 classes, 20 orders, 32 families, and 119 genera. These data were then analyzed using mediation Mendelian randomization (MR) analyses to explore the potential mediating effect of diabetes complications risk factors on the relationship between gut microbiota and specific diabetic complications such as diabetic kidney disease (DKD), ketoacidosis, and diabetic retinopathy (DR).ResultsIn our Mendelian analysis, we observed negative associations between Bifidobacterial order and Actinomycete phylum with DKD in type 1 diabetes (T1D) as well as early DKD in T1D. Conversely, these taxa showed positive associations with ketoacidosis in type 2 diabetes (T2D). In reverse Mendelian analysis, we found that DR in both T1D and T2D as well as ketoacidosis in T2D affected the abundance of Eubacterium fissicaten genus and LachnospiraceaeUCG010 family within the gut microbiota.ConclusionsOur findings provide compelling evidence for causal relationships between specific GM taxa and various diabetes complications. These insights contribute valuable knowledge for developing treatments targeting diabetes-related complications.

Topiroxostat improves glomerulosclerosis in type 2 diabetic Nagoya Shibata Yasuda mice with early diabetic kidney disease

Reactive oxygen species production might be prevented by xanthine oxidoreductase (XOR) inhibitors, which can cause glomerulosclerosis. We aimed to investigate whether topiroxostat, an XOR inhibitor, prevents diabetic kidney disease development in mice. Six-week-old control Institute of Cancer Research (ICR) mice and type 2 diabetic Nagoya Shibata Yasuda (NSY) mice were divided into the ICR group (ICR mice which received a lard-containing high-fat diet [HFD] based on the AIN-93G diet), NSY control group (NSY mice which received the same aforementioned diet), and NSY + topiroxostat group (NSY mice which received the same aforementioned diet with addition of 0.0012% topiroxostat). After 20 weeks, plasma biomarkers, XOR activity and oxidative stress levels, which were assessed using malondialdehyde (MDA), were measured through enzyme-linked immunosorbent assay or enzymatic methods. Renal pathology was evaluated using periodic acid–Schiff staining. Redox gene and protein expression were determined using RT-qPCR and western blotting, respectively. Plasma XOR activity was lower in NSY mice treated with topiroxostat than those without. Plasma cystatin C and creatinine levels did not differ between the ICR and NSY control groups or between the NSY control and NSY + topiroxostat groups. The NSY + topiroxostat group showed a smaller mesangial area than the NSY control group. The mRNA expression of Sod3, Prdx1, Gpx2, and Gpx3 was higher in the NSY + topiroxostat group than in the NSY control group. Renal MDA levels were lower in the NSY + topiroxostat group than in the NSY control group. Topiroxostat can reduce glomerulosclerosis, and the reduction is associated with renal oxidative markers.

Perfluoroalkyl Substances and Risk of Early Diabetic Kidney Disease in Youth with Type 2 Diabetes: A Prospective Study

Perfluoroalkyl Substances and Risk of Early Diabetic Kidney Disease in Youth with Type 2 Diabetes: A Prospective Study

Biomarker Profiling with Targeted Metabolomic Analysis of Plasma and Urine Samples in Patients with Type 2 Diabetes Mellitus and Early Diabetic Kidney Disease.

Background: Over the years, it was noticed that patients with diabetes have reached an alarming number worldwide. Diabetes presents many complications, including diabetic kidney disease (DKD), which can be considered the leading cause of end-stage renal disease. Current biomarkers such as serum creatinine and albuminuria have limitations for early detection of DKD. Methods: In our study, we used UHPLC-QTOF-ESI+-MS techniques to quantify previously analyzed metabolites. Based on one-way ANOVA and Fisher's LSD, untargeted analysis allowed the discrimination of six metabolites between subgroups P1 versus P2 and P3: tryptophan, kynurenic acid, taurine, l-acetylcarnitine, glycine, and tiglylglycine. Results: Our results showed several metabolites that exhibited significant differences among the patient groups and can be considered putative biomarkers in early DKD, including glycine and kynurenic acid in serum (p < 0.001) and tryptophan and tiglylglycine (p < 0.001) in urine. Conclusions: Although we identified metabolites as potential biomarkers in the present study, additional studies are needed to validate these results.

Role and Mechanisms of Tyro3 in Podocyte Biology and Glomerular Disease

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; Podocyte loss occurs in both primary and secondary glomerular diseases, leading to the progression of kidney disease. A large body of evidence suggests that apoptosis and detachment are the mechanisms mediating the reduction in podocyte numbers in glomerular diseases. Recent studies demonstrate a renal protective effect of protein S (PS) through the activation of Tyro3, one of the TAM receptors. Tyro3 is predominantly expressed in podocytes within the kidney, and its expression increases in early diabetic kidney disease (DKD) but decreases in patients with progressive DKD and focal segmental glomerulosclerosis (FSGS). Glomerular expression of Tyro3 also correlates with the progression of DKD and predicts the progression of primary glomerular diseases. High glucose increases Tyro3 expression, while TNF-α suppresses the expression of PS and Tyro3. PS has anti-inflammatory and antiapoptotic effects in podocytes, likely via the activation of the Akt pathway and the inhibition of NF-kB activation. In vivo, the knockout of PS or Tyro3 exacerbates podocyte loss and glomerular disease, while the overexpression of PS and Tyro3 attenuates the injury in mice with DKD and FSGS. Tyro3 agonists have also been shown to protect podocytes from injury in these animal models. &lt;b&gt;&lt;i&gt;Summary:&lt;/i&gt;&lt;/b&gt; Tyro3 plays a critical role in podocyte biology and glomerular disease. Tyro3 agonists could potentially be developed as a new therapy for glomerular disease. &lt;b&gt;&lt;i&gt;Key Message:&lt;/i&gt;&lt;/b&gt; The aim of this review article was to summarize the role and mechanisms mediating the protective effects of Tyro3 in podocyte biology and glomerular disease. Additionally, we discuss the possibility of developing Tyro3 agonists as potential treatment for glomerular diseases.

Krüppel-like factor 2 is an endoprotective transcription factor in diabetic kidney disease.

Diabetic kidney disease (DKD) is a microvascular complication of diabetes, and glomerular endothelial cell (GEC) dysfunction is a key driver of DKD pathogenesis. Krüppel-like factor 2 (KLF2), a shear stress-induced transcription factor, is among the highly regulated genes in early DKD. In the kidney, KLF2 expression is mostly restricted to endothelial cells, but its expression is also found in immune cell subsets. KLF2 expression is upregulated in response to increased shear stress by the activation of mechanosensory receptors but suppressed by inflammatory cytokines, both of which characterize the early diabetic kidney milieu. KLF2 expression is reduced in progressive DKD and hypertensive nephropathy in humans and mice, likely due to high glucose and inflammatory cytokines such as TNF-α. However, KLF2 expression is increased in glomerular hyperfiltration-induced shear stress without metabolic dysregulation, such as in settings of unilateral nephrectomy. Lower KLF2 expression is associated with CKD progression in patients with unilateral nephrectomy, consistent with its endoprotective role. KLF2 confers endoprotection by inhibition of inflammation, thrombotic activation, and angiogenesis, and thus KLF2 is considered a protective factor for cardiovascular disease (CVD). Based on similar mechanisms, KLF2 also exhibits renoprotection, and its reduced expression in endothelial cells worsens glomerular injury and albuminuria in settings of diabetes or unilateral nephrectomy. Thus KLF2 confers endoprotective effects in both CVD and DKD, and its activators could potentially be developed as a novel class of drugs for cardiorenal protection in diabetic patients.

Serum angiopoietin-2: a promising biomarker for early diabetic kidney disease in children and adolescents with type 1 diabetes

Albuminuria has been considered the golden standard biomarker for diabetic kidney disease (DKD), but appears once significant kidney damage has already occurred. Angiopoietin-2 (Angpt-2) has been implicated in the development and progression of DKD in adults. We aimed to explore the association of serum Angpt-2 levels with DKD in children and adolescents with type 1 diabetes mellitus (T1DM) of short duration (3–5 years) and to evaluate the predictive power of serum Angpt-2 in the early detection of DKD prior to the microalbuminuric phase. The current cross-sectional study included 90 children divided into three age and sex-matched groups based on urinary albumin-to-creatinine ratio (UACR): microalbuminuric diabetic group (n = 30), non-albuminuric diabetic group (n = 30), and control group (n = 30). All participants were subjected to anthropometric measurements, serum Angpt-2 and fasting lipid profile (total cholesterol, triglycerides, LDL-C, HDL-C, and Non-HDL-C) assessment. Glomerular filtration rate was estimated based on serum creatinine (eGFR-Cr). Higher serum Angpt-2 levels were detected in both diabetic groups compared to controls and in microalbuminuric compared to non-albuminuric diabetic group. There was no detected significant difference in eGFR-Cr values across the study groups. Serum Angpt-2 was positively correlated with triglycerides, LDL, Non-HDL-C, HbA1c, and UACR, while UACR, HbA1c, and Non-HDL-C were independent predictors for serum Angpt-2. Serum Angpt-2 at level of 137.4 ng/L could discriminate between microalbuminuric and non-albuminuric diabetic groups with AUC = 0.960 and at level of 115.95 ng/L could discriminate between the non-albuminuric diabetic group and controls with AUC = 0.976.Conclusion: Serum Angpt-2 is a promising potent biomarker for the detection of early stage of DKD in childhood T1DM before albuminuria emerges.What is Known?• Urine albumin-to-creatinine ratio (UACR) and glomerular filtration rate (GFR) are the golden standard but late biomarkers for DKD.• Angiopoietin-2 has been implicated in the development and progression of DKD in adults with diabetes, but has not been explored in T1DM children with DKD.What is New?• Higher serum angiopoietin-2 was detected in diabetic groups compared to controls and in microalbuminuric compared to non-albuminuric group.• Angiopoietin-2 correlated positively with triglycerides, LDL, Non-HDL-C, HbA1c, and UACR.• Serum angiopoietin-2 is a promising early diagnostic biomarker for DKD in children with T1DM.

1342-P: A Predictive Model for Five-Year Early Diabetic Kidney Disease

1342-P: A Predictive Model for Five-Year Early Diabetic Kidney Disease

Primary care clinician perspectives on automated nephrology e-consults for diabetic kidney disease: a pre-implementation qualitative study

BackgroundMany patients with diabetic kidney disease (DKD) do not receive evidence-based, guideline-recommended treatment shown to reduce DKD progression and complications. Proactive electronic consultations (e-consults) are an emerging intervention strategy that could potentially allow nephrologists to provide timely and evidence-based guidance to primary care providers (PCPs) engaged in early DKD care.MethodsThe objective of this study was to explore perspectives about potential barriers and facilitators associated with a proactive e-consult program to improve DKD care delivery. We conducted semi-structured qualitative interviews with PCPs across three different health systems. Interview transcripts were reviewed in a rapid qualitative analysis approach to iteratively identify, refine, and achieve consensus on a final list of themes and subthemes.ResultsA total of 18 interviews were conducted. PCPs across all sites identified similar challenges to delivering guideline-recommended DKD care. PCPs were supportive of the proactive e-consult concept. Three major themes emerged surrounding (1) perceived potential benefits of proactive e-consults, including educational value and improved specialist access; (2) concerns about the proactive nature of e-consults, including the potential to increase PCP workload and the possibility that e-consults could be seen as documenting substandard care; and (3) leveraging of care teams to facilitate recommended DKD care, such as engaging clinic-based pharmacists to implement specialist recommendations from e-consults.ConclusionIn this pre-implementation qualitative study, PCPs noted potential benefits and identified concerns and implementation barriers for proactive e-consults for DKD care. Strategies that emerged for promoting successful implementation included involving clinic support staff to enact e-consult recommendations and framing e-consults as a system improvement effort to avoid judgmental associations.

#781 Cerebral vessels and early diabetic kidney disease in type 2 diabetes mellitus patients share a common mitochondrial DNA and inflammatory profile

Abstract Background and Aims Cerebrovascular disease accounts for major motor and cognitive disabilities in patients with type 2 diabetes mellitus (DM). Among the multiple pathogenic pathways which involve both the kidney and the brain vasculature, inflammation and mitochondrial dysfunction are of major importance. The aim of the study was to evaluate the association of mitochondrial DNA (mtDNA) modifications in blood and urine and of inflammatory markers with cerebral vessels structural and functional modifications in patients with type 2 DM and early diabetic kidney disease (DKD). Method A cohort of 150 patients (52 patients with normoalbuminuria, 48 patients with microalbuminuria, and 50 patients with macroalbuminuria) and 30 age- and gender-matched healthy controls were enrolled in this case series study. All patients were assessed concerning urinary albumin/creatinine ratio (UACR), biomarkers of podocyte damage (synaptopodin, podocalyxin) and of proximal tubule dysfunction (kidney injury molecule-1-KIM-1, N-acetyl-β-(D)-glucosaminidase-NAG), serum and urinary pro-inflammatory interleukins IL-17A, IL-18, tumor necrosis factor alpha (TNFα), intercellular adhesion molecule-1 (ICAM-1), anti-inflammatory IL-10, and eGFR (creatinine-cystatin C). MtDNA-CN and nuclear DNA (nDNA) were quantified in peripheral blood and urine by qRT-PCR (ABI 7900-HT–Applied BioSystem). TaqMan assays were utilized for the assessment of cytochrome b (CYTB) gene, subunit 2 of NADH dehydrogenase (ND2), and of beta 2 microglobulin nuclear gene (B2M). mtDNA-CN was defined as the ratio of the number of mtDNA/nDNA copies, through analysis of the CYTB/B2M and ND2/B2M ratio. The cerebrovascular hemodynamic indices were evaluated by an ultrasound equipment with high resolution (MYLAB 8-ESAOTE Italy) equipped with a Colour Ultrasound System. Subclinical atherosclerosis and arteriosclerosis were assessed by intima-media thickness (IMT) in the common carotid arteries (CCAs), Gosling's pulsatility index (PI) and Pourcellot's resistivity index (RI) in the internal carotid arteries (ICAs) and middle cerebral arteries (MCAs), bilaterally. Cerebrovascular reactivity (CVR), which represents the vasodilatory reactivity of cerebral vessels in response to a vasodilatory stimulus, was assessed by the breath-holding test where hypercapnia was the vasodilatory stimulus and the breath-holding index (BHI) was calculated. Results Multivariable linear analysis revealed direct correlations of serum TNFα with UACR, KIM-1, NAG, and urinary mtDNA, and a negative correlation with serum mtDNA (R2 = 0.893; p &amp;lt; 0.0001); urinary TNFα correlated directly with UACR, KIM-1, NAG, and urinary mtDNA (R2 = 0.693; p &amp;lt; 0.0001). Serum ICAM-1 had a direct correlation with UACR, KIM-1, NAG, synaptopodin, and podocalyxin, and a negative one with serum mtDNA (R2 = 0.855; p &amp;lt; 0.0001). Urinary ICAM-1 correlated directly with UACR, KIM-1, NAG, and urinary mtDNA, and indirectly with eGFR (R2 = 0.783; p &amp;lt; 0.0001). CCA-IMT had a direct correlation with serum IL-17A and indirect correlations with serum mtDNA and serum IL-10 (R2 = 0.706; p &amp;lt; 0.0001); ICA-PIs and MCA-PIs correlated directly with serum IL-17A and negatively with serum IL-10, respectively (R2 = 0.567; R2 = 0.642; p &amp;lt; 0.0001). ICA-RIs showed a direct correlation with UACR, serum and urinary IL-17A, serum and urinary IL-18, NAG, and urinary TNFα, and a negative correlation with serum mtDNA and with serum and urinary IL-10 (R2 = 0.930; p &amp;lt; 0.0001). MCA-RIs correlated directly with UACR, serum IL-17A, serum IL-18, NAG, urinary mtDNA, and urinary TNFα, and negatively with serum mtDNA and serum IL-10 (R2 = 0.875; p &amp;lt; 0.0001). BHI correlated directly with serum IL-10 and serum mtDNA, and negatively with serum IL-17A, serum ICAM-1, and NAG (R2 = 0.823; p &amp;lt; 0.0001). Conclusion In neurologically asymptomatic type 2 DM patients there is an association of mtDNA changes in blood and urine with cerebral vessels atherosclerotic and arteriosclerotic remodeling, as well as with decreased CVR. MtDNA modifications may exert their effect in parallel with markers of inflammation at both kidney and cerebrovascular level from the early stages of DKD.

#1831 Circulating MiRNA 195-5p may be associated with early renal impairment in patients with prediabetes

Abstract Background and Aims Type 2 diabetes mellitus (DM) is one of the leading causes of chronic kidney disease worldwide. However, there are few data concerning early kidney impairment in prediabetes patients. The aim of the study was to demonstrate early kidney damage in patients with prediabetes by assessing proximal tubule (PT) dysfunction, podocytes injury, and miRNA expression. Method A cohort of 192 individuals were analysed and divided such as follows: 52-normoalbuminuria-, 48-microalbuminuria-, and 50-macroalbuminuria type 2 DM patients, respectively; 12 patients-prediabetes and 30-healthy controls. The miRNA profile was assessed by real-time PCR, while PT dysfunction biomarker, N-acetyl-β-D-glucosaminidase (NAG), and podocyte injury biomarker, podocalyxin, were assessed by ELISA technique. The study was conducted in two distinct stages. In the first part of the study was detected a particular miRNAs profile in serum in patients with prediabetes; subsequently, the expression of the most relevant miRNA in patients with prediabetes was identified. Results i) in prediabetes patients, serum miRNA195-5p was 2.69 fold change as compared to the control group and correlated with NAG (p&amp;lt;0.05) and podocalyxin (p&amp;lt;0.03); ii) in type 2 DM patients, the expression of serum miRNA195-5p was higher and correlated with NAG (p&amp;lt;0.05), podocalyxin (p&amp;lt;0.04), urinary albumin: creatinine ratio (p&amp;lt;0.001) and with eGFR (p&amp;lt;0.001); iii) urinary NAG and urinary podocalyxin were higher in prediabetes patients and type 2 DM patients, even in the normoalbuminuria stage, as compared to controls (p&amp;lt;0.04; p&amp;lt;0.001). Conclusion A panel of molecular biomarkers, such as miRNAs, remain useful tools for the early diagnosis of renal involvement in the course of type 2 DM. MiRNA 195-5p may be associated with PT dysfunction and podocyte damage, and could predict renal dysfunction in both prediabetes and early diabetic kidney disease in type 2 DM patients.

#1076 DNA hypomethylation of Syk induces oxidative stress and apoptosis via the PKCβ/ P66shc signaling pathway in diabetic kidney disease

Abstract Background and Aims Epigenetic alterations, especially DNA methylation, have been shown to play a role in the pathogenesis of diabetes mellitus (DM) and its complications, including diabetic kidney disease (DKD). Spleen tyrosine kinase (Syk) is known to be involved in immune and inflammatory disorders. We, therefore, investigated the possible involvement of Syk promoter methylation in DKD, and the mechanisms underlying this process. Method Kidney tissues were obtained from renal biopsies of patients with early and advanced DKD. A diabetic mouse model (ApoE−/−DM) was generated from ApoE knockout (ApoE−/−) mice using a high fat and high glucose diet combined with low-dose streptozocin (STZ) intraperitoneal injection. We also established an in vitro model using HK2 cells. Results A marked elevation in the expression levels of Syk, PKCβ, and P66shc in renal tubules was observed in patients with DKD. In ApoE−/− DM mice, Syk expression and the binding of Sp1 to the Syk gene promoter were both increased in the kidney. In addition, the promoter region of the Syk gene exhibited hypomethylation. Syk inhibitor (R788) intervention improved renal function and alleviated pathologic changes in ApoE−/− DM mice. Moreover, R788 intervention alleviated oxidative stress and apoptosis and down-regulated the expression of PKCβ/ P66shc signaling pathway proteins. In HK2 cells, oxLDL combined with high glucose stimulation upregulated Sp1 expression in the nucleus (compared with control and oxLDL groups), and this was accompanied by an increase in the binding of Sp1 to the Syk gene promoter. SP1 silencing down-regulated the expression of Syk and inhibited the production of reactive oxygen species and cell apoptosis. Finally, PKC agonist intervention reversed the oxidative stress and apoptosis induced by Syk inhibitor (R406). Conclusion In DKD, hypomethylation at the Syk gene promoter was accompanied by an increase in Sp1 binding at the promoter. As a consequence of this enhanced Sp1 binding, Syk gene expression was upregulated. Syk inhibitors could attenuate DKD-associated oxidative stress and apoptosis via down-regulation of PKCβ/ P66shc signaling pathway proteins. Together, our results identify Syk as a promising target for intervention in DKD.

#1071 The effect and mechanism of SGLT2 inhibitor on improving inflammatory injury of glomerular endothelial cells in diabetes

Abstract Background and Aims ATP-binding cassette transporter A1 (ABCA1), which reduces intracellular cholesterol accumulation, is highly expressed in the kidney. Studies have shown that sodium-glucose co-transporter 2 inhibitors (SGLT2) inhibitors promote ABCA1 expression in multiple tissues and organs. However, the effect of SGLT2 inhibitors on ABCA1 expression in diabetic kidney disease (DKD) is unclear. In this study, the effect of empagliflozin, an SGLT2 inhibitor, on ABCA1 in glomerular endothelial cells(GECs) of DKD and the possible mechanisms linking ABCA1 to GECs inflammatory injury were investigated. Method Kidney tissues were obtained from renal biopsies of patients with early and advanced DKD. db/db mice were used as animal models of type 2 diabetes and the effects of SGLT2 inhibitors on ABCA1 were analyzed by treatment with empagliflozin. The effects of ABCA1 overexpression on glomerular lipid deposition and kidney injury were examined in a type 2 diabetic mouse model with ABCA1 overexpression (db/db + ABCA1 mice), and human renal glomerular endothelial cells (HRGECs) cultured in high glucose and high cholesterol conditions, which simulated type 2 diabetes in vitro. Results The expression of ABCA1 in the glomeruli of DKD patients and db/db mice was significantly decreased. Enhancing ABCA1 expression in the kidney tissue of diabetic mice by adenovirus transduction improved renal cholesterol deposition, inhibited the overactivation of C3a/C5a, and improved renal inflammatory injury. In addition, in cultured HRGECs under high glucose and high cholesterol conditions, ABCA1 deficiency increased the deposit of cellular cholesterol, contributed to overactivation of C3a/C5a, and induced inflammatory injury. Overexpression of ABCA1 enhancing cholesterol efflux or inhibition of C3a/C5a activation in vitro significantly protected against glomerular endothelial injury stimulated by high glucose and high cholesterol. Moreover, SGLT2 inhibitor empagliflozin up-regulated the expression of ABCA1 and down-regulated the levels of cholesterol, C3a/C5a and inflammatory cytokines in diabetic mice and HRGECs. Conclusion SGLT2 inhibitor (empagliflozin) might play a renal protective role by up-regulating ABCA1-mediated cholesterol outflow, inhibiting the activation of C3a/C5a, and then ameliorating the inflammatory injury of GECs.

Patients With Type 2 Diabetes Mellitus and Early Diabetic Kidney Disease Exhibit Lower Computed Tomography-measured Skeletal Muscle Attenuation Values: A Propensity Score-matched Study

ObjectiveTo investigate the association between computed tomography (CT)-measured quality characteristics of skeletal muscle (SM) and early diagnosis of diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM). MethodsThis retrospective study included patients diagnosed with T2DM, with and without early DKD, between January 2019 and December 2021. To reduce potential bias, propensity score matching (PSM) was performed. The area and CT attenuation values for SM and different abdominal adipose depots were measured. After PSM, logistic and multiple linear regression analyse were performed to analyse risk factors for early DKD. ResultsA total of 267 patients were enrolled (mean age, 61.67 years ±10.87; 155 men) and divided into two groups: T2DM with early DKD (n=133); and T2DM without DKD (n=134). After PSM, 230 patients were matched (T2DM with early DKD [n=115]; and T2DM without DKD [n=115]), with no statistical differences in general characteristics between the two groups (P>0.05). In multivariate logistic regression analysis, high-density lipoprotein cholesterol (odds ratio [OR] 0.14; 95% confidence interval [CI] 0.04–0.49; P=0.002), uric acid (OR 1.01; 95% CI 1.00–1.01; P=0.006), and SM attenuation value (OR 0.94; 95% CI 0.90–0.98; P=0.003) were independent risk factors for early DKD. Multiple linear regression analysis revealed significant correlations between SM attenuation value and cystatin C (β=-0.39, P=0.004), urine albumin-to-creatinine ratio (β=-0.26, P=0.026), and estimated glomerular filtration rate (β=0.31 P=0.009) after adjustment for confounders. ConclusionT2DM patients with lower SM attenuation values may exhibit a higher risk for early DKD than those with higher values, which provides a potential imaging biomarker for early DKD diagnosis.

Systemic administration of miR-451 improves autophagy response in an accelerated mouse model of diabetic kidney disease

Diabetic kidney disease (DKD) is a common and severe microvascular complication of both type 1 and type 2 diabetes mellitus. It is the most common cause of end stage renal disease in the United States. Autophagy is a highly conserved pathway that recycles damaged organelles and macromolecules to maintain intracellular homeostasis. There is mounting evidence highlighting the role of autophagy in diabetic kidney disease. MicroRNAs (miRNA) affect the transcription of several genes involved in the development and progression of DKD, regulating key pathways and processes, including fibrotic signaling and autophagy. Thus, the dysregulation of miRs exacerbates kidney injury in the diabetic setting. Previous work from our group suggests that chronic systemic inhibition of miR-451 exacerbates fibrosis in the kidney of an obese insulin resistant mouse model (tallyHo/Jng), indicating a potential renoprotective role for miR-451 in the diabetic kidney. However, few studies have investigated this protective role of miR-451 in the diabetic kidney. This study aimed to understand the renoprotective effects of miR-451 in an accelerated mouse model of DKD. BTBR ob/ob mice rapidly develop morphological renal lesions characteristic of both early and advanced human DKD, with proteinuria typically beginning at 4-weeks of age. 12-week old male black and tan, brachyuric (BTBR) ob/ob mice and BTBR wild-type mice were treated with commercially available miR-451 mimics (2mg/kg/bw; n=3/treatment group; treatment groups: WT, BTBR ob/ob, WT+miR-451, and BTBR ob/ob+miR-451) 1X per week for 3-consective weeks. Spot urine was collected weekly until the end of study. Random blood glucose was measured by tail prick weekly. Mice were humanely euthanized, and kidneys and blood harvested at the end of the treatment period. Western blotting of whole kidney homogenate was performed following a standard protocol. Data was analyzed using students t-test or ANOVA, where appropriate, p&lt;0.05 considered significant. Albumin: creatinine ratio was four times higher (p=0.01) in BTBR ob/ob mice beginning at 5 weeks. Treatment with miR-451 mimics had no significant effect on body weight in either group. Blood glucose was significantly higher in miR-451 treated and untreated BTBR ob/ob mice at 12-weeks (425± 33.1 mg/dL; p=0.04) and 13-weeks (383± 25.3 mg/dL; p=0.007). However, blood glucose decreased significantly from week 13 (554.7± 10.8 mg/dL) to week 14(289± 13.3 mg/dL; p=0.0002) in BTBR ob/ob miR-451 treated mice. Western blot analysis of MiR-451 mimic treated BTBR ob/ob and WT mice whole kidney homogenate revealed a 91% (p=0.02) and 95% (p=0.01) reduction, respectively, in YWHAZ (a predicted miR-451 target). Conversely, western blot analysis of autophagy related proteins revealed a 68% (p=0.01) increase in ATG101 and a 44% increase in Beclin-1 in miR-451 mimic treated BTBR ob/ob mice. Collectively, the findings of this study suggest that miR-451 may offer protection in the diabetic kidney via autophagic signaling and improved blood glucose control. GHUCCTS KL2 Scholar Program (Award Number: KL2TR001432) The Charles and Mary Latham Fund Howard University Department of Medicine Start-Up Funds; Howard University Bridge Fund and Pilot Study Awards. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Mitochondrial DNA and Inflammation Are Associated with Cerebral Vessel Remodeling and Early Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus.

Cerebrovascular disease accounts for major neurologic disabilities in patients with type 2 diabetes mellitus (DM). A potential association of mitochondrial DNA (mtDNA) and inflammation with cerebral vessel remodeling in patients with type 2 DM was evaluated. A cohort of 150 patients and 30 healthy controls were assessed concerning urinary albumin/creatinine ratio (UACR), synaptopodin, podocalyxin, kidney injury molecule-1 (KIM-1), N-acetyl-β-(D)-glucosaminidase (NAG), interleukins IL-17A, IL-18, IL-10, tumor necrosis factor-alpha (TNFα), intercellular adhesion molecule-1 (ICAM-1). MtDNA-CN and nuclear DNA (nDNA) were quantified in peripheral blood and urine by qRT-PCR. Cytochrome b (CYTB) gene, subunit 2 of NADH dehydrogenase (ND2), and beta 2 microglobulin nuclear gene (B2M) were assessed by TaqMan assays. mtDNA-CN was defined as the ratio of the number of mtDNA/nDNA copies, through analysis of the CYTB/B2M and ND2/B2M ratio; cerebral Doppler ultrasound: intima-media thickness (IMT)-the common carotid arteries (CCAs), the pulsatility index (PI) and resistivity index (RI)- the internal carotid arteries (ICAs) and middle cerebral arteries (MCAs), the breath-holding index (BHI). The results showed direct correlations of CCAs-IMT, PI-ICAs, PI-MCAs, RI-ICAs, RI-MCAs with urinary mtDNA, IL-17A, IL-18, TNFα, ICAM-1, UACR, synaptopodin, podocalyxin, KIM-1, NAG, and indirect correlations with serum mtDNA, IL-10. BHI correlated directly with serum IL-10, and serum mtDNA, and negatively with serum IL-17A, serum ICAM-1, and NAG. In neurologically asymptomatic patients with type 2 DM cerebrovascular remodeling and impaired cerebrovascular reactivity may be associated with mtDNA variations and inflammation from the early stages of diabetic kidney disease.

DNA hypomethylation of Syk induces oxidative stress and apoptosis via the PKCβ/P66shc signaling pathway in diabetic kidney disease.

Epigenetic alterations, especially DNA methylation, have been shown to play a role in the pathogenesis of diabetes mellitus (DM) and its complications, including diabetic kidney disease (DKD). Spleen tyrosine kinase (Syk) is known to be involved in immune and inflammatory disorders. We, therefore, investigated the possible involvement of Syk promoter methylation in DKD, and the mechanisms underlying this process. Kidney tissues were obtained from renal biopsies of patients with early and advanced DKD. A diabetic mouse model (ApoE-/- DM) was generated from ApoE knockout (ApoE-/-) mice using a high-fat and high-glucose diet combined with low-dose streptozocin intraperitoneal injection. We also established an invitro model using HK2 cells. A marked elevation in the expression levels of Syk, PKCβ, and P66shc in renal tubules was observed in patients with DKD. In ApoE-/- DM mice, Syk expression and the binding of Sp1 to the Syk gene promoter were both increased in the kidney. In addition, the promoter region of the Syk gene exhibited hypomethylation. Syk inhibitor (R788) intervention improved renal function and alleviated pathologic changes in ApoE-/- DM mice. Moreover, R788 intervention alleviated oxidative stress and apoptosis and downregulated the expression of PKCβ/P66shc signaling pathway proteins. In HK2 cells, oxLDL combined with high-glucose stimulation upregulated Sp1 expression in the nucleus (compared with control and oxLDL groups), and this was accompanied by an increase in the binding of Sp1 to the Syk gene promoter. SP1 silencing downregulated the expression of Syk and inhibited the production of reactive oxygen species and cell apoptosis. Finally, PKC agonist intervention reversed the oxidative stress and apoptosis induced by Syk inhibitor (R406). In DKD, hypomethylation at the Syk gene promoter was accompanied by an increase in Sp1 binding at the promoter. As a consequence of this enhanced Sp1 binding, Syk gene expression was upregulated. Syk inhibitors could attenuate DKD-associated oxidative stress and apoptosis via downregulation of PKCβ/P66shc signaling pathway proteins. Together, our results identify Syk as a promising target for intervention in DKD.

Co-differential genes between DKD and aging: implications for a diagnostic model of DKD.

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus (DM) that is closely related to aging. In this study, we found co-differential genes between DKD and aging and established a diagnostic model of DKD based on these genes. Differentially expressed genes (DEGs) in DKD were screened using GEO datasets. The intersection of the DEGs of DKD and aging-related genes revealed DKD and aging co-differential genes. Based on this, a genetic diagnostic model for DKD was constructed using LASSO regression. The characteristics of these genes were investigated using consensus clustering, WGCNA, functional enrichment, and immune cell infiltration. Finally, the expression of diagnostic model genes was analyzed using single-cell RNA sequencing (scRNA-seq) in DKD mice (model constructed by streptozotocin (STZ) injection and confirmed by tissue section staining). First, there were 159 common differential genes between DKD and aging, 15 of which were significant. These co-differential genes were involved in stress, glucolipid metabolism, and immunological functions. Second, a genetic diagnostic model (including IGF1, CETP, PCK1, FOS, and HSPA1A) was developed based on these genes. Validation of these model genes in scRNA-seq data revealed statistically significant variations in FOS, HSPA1A, and PCK1 gene expression between the early DKD and control groups. Validation of these model genes in the kidneys of DKD mice revealed that Igf1, Fos, Pck1, and Hspa1a had lower expression in DKD mice, with Igf1 expression being statistically significant. Our findings suggest that DKD and aging co-differential genes are significant in DKD diagnosis, providing a theoretical basis for novel research directions on DKD.

Insights into serum metabolic biomarkers for early detection of incident diabetic kidney disease in Chinese patients with type 2 diabetes by random forest.

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease (ESRD) worldwide. Early detection is critical for the risk stratification and early intervention of progressive DKD. Serum creatinine (sCr) and urine output are used to assess kidney function, but these markers are limited by their delayed changes following kidney pathology, and lacking of both sensitivity and accuracy. Hence, it is essential to illustrate potential diagnostic indicators to enhance the precise prediction of early DKD. A total of 194 Chinese individuals include 30 healthy participants (Stage 0) and 164 incidents with type 2 diabetes (T2D) spanning from DKD's Stage 1a to 4 were recruited and their serums were subjected for untargeted metabolomic analysis. Random forest (RF), a machine learning approach, together with univariate linear regression (ULR) and multivariate linear regression (MvLR) analysis were applied to characterize the features of untargeted metabolites of DKD patients and to identify candidate DKD biomarkers. Our results indicate that 2-(α-D-mannopyranosyl)-L-tryptophan (ADT), succinyladenosine (SAdo), pseudouridine and N,N,N-trimethyl-L-alanyl-L-proline betaine (L-L-TMAP) were associated with the development of DKD, in particular, the latter three that were significantly elevated in Stage 2-4 T2D incidents. Each of the four metabolites in combination with sCr achieves better performance than sCr alone with area under the receiver operating characteristic curve (AUC) of 0.81-0.91 in predicting DKD stages. An average of 3.9 years follow-up study of another cohort including 106 Stage 2-3 patients suggested that "urinary albumin-to-creatinine ratio (UACR) + ADT + SAdo" can be utilized for better prognosis evaluation of early DKD (average AUC = 0.9502) than UACR without sexual difference.