High Serum Uric Acid Is Associated with Tubular Damage and Kidney Inflammation in Patients with Type 2 Diabetes

Effects of sodium-glucose cotransporter 2 inhibitors on renal risk factors in patients with abnormal glucose metabolism: a meta-analysis of randomized controlled trials

AIMS

Several trials have assessed the antihyperglycemic effects of sodium-glucose cotransporter 2 inhibitors (SGLT2Is) in patients with type 2 diabetes mellitus (T2DM). We conducted a quantitative analysis to assess the effects of SGLT2Is on renal risk factors in patients with abnormal glucose metabolism.

MATERIALS AND METHODS

Randomized controlled trials (RCTs) were identified by searching the PubMed, Embase, Scopus, and Web of Science databases published before September 30, 2022. The intervention group received SGLT2Is as monotherapy or add-on treatment, and the control group received placebos, standard care, or active control. Risk of bias assessment was performed using the Cochrane risk of bias assessment tool. Meta-analysis was performed on studies with abnormal glucose metabolism populations and studies using the weighted mean differences (WMDs) as the measure of the effect size. Clinical trials providing changes in serum uric acid (SUA) were included. The mean change of SUA, glycated hemoglobin (HbA1c), body mass index (BMI), and estimated glomerular filtration rate (eGFR) were calculated.

RESULTS

After a literature search and detailed evaluation, a total of 11 RCTs were included for quantitative analysis to analyze the differences between the SGLT2I group and the control group. The results showed that SGLT2I significantly reduced SUA (MD =  -0.56, 95% CI =  -0.66 ~ -0.46, I² = 0%, P < 0.00001), HbA1c (MD =  -0.20, 95% CI =  -0.26 ~ -0.13, I² = 0%, P < 0.00001), and BMI (MD =  -1.19, 95% CI =  -1.84 ~ -0.55, I² = 0%, P = 0.0003). There was no significant difference in the reduction of eGFR observed in the SGLT2I group (MD =  -1.60, 95% CI =  -3.82 ~ 0.63, I² = 13%, P = 0.16).

CONCLUSIONS

These results showed that the SGLT2I group caused greater reductions in SUA, HbA1c, and BMI but had no effect on eGFR. These data suggested that SGLT2Is may have numerous potentially beneficial clinical effects in patients with abnormal glucose metabolism. However, these results need to be consolidated by further studies.

Urinary levels of kidney injury molecule-1 (KIM-1) and interleukin-18 (IL-18) in children and adolescents with hyperuricemia

PURPOSE

Hyperuricemia may lead to silent tissue damage and increase the risk of some diseases, including kidney diseases. Increased serum uric acid concentration induces inflammatory pathways and promotes kidney damage. This study aimed to determine whether hyperuricemia influences the levels of urinary kidney injury markers in children and adolescents with hyperuricemia, assessed by the urinary concentrations of interleukin-18, a biomarker of inflammation, and kidney injury molecule-1 (KIM-1), a biomarker of kidney injury.

MATERIAL AND METHODS

The study included 73 children and adolescents (32 males and 41 females) aged 2-18 years. They were divided into two groups: hyperuricemia (HU) group (n ​= ​48) and normouricemia - reference group (R) (n ​= ​25). The concentrations of urinary interleukin-18 and KIM-1 were measured using an ELISA kit and were normalized for urinary creatinine (cr.) concentration.

RESULTS

The median interleukin-18/cr. Levels in the HU group were significantly higher than in the R group (median, Q1-Q3) 21.83 (11.32-35.96) and 12.68 (7.11-24.04), respectively, (p ​< ​0.05). The KIM-1/cr. in the HU group and the R group were (median, Q1-Q3) 0.79 (0.45-1.03) and 0.81 (0.59-1.01), respectively, and the difference was not significant. KIM-1/cr. did not differ between the groups. Interleukin-18/cr. ratio correlated positively with serum uric acid concentration (r ​= ​0.24, p ​< ​0.05).

CONCLUSIONS

Interleukin-18/cr., but not KIM-1/cr. was higher in children with hyperuricemia. Hyperuricemia results in increased IL-18 in urine, in absence of other markers of kidney injury, suggesting inflammation in the kidney. Additional studies on the adults should be done, to confirm this hypothesis.

Research progress of risk factors and early diagnostic biomarkers of gout-induced renal injury

Gout renal injury has an insidious onset, no obvious symptoms, and laboratory abnormalities in the early stages of the disease. The injury is not easily detected, and in many cases, the patients have entered the renal failure stage at the time of diagnosis. Therefore, the detection of gout renal injury–related risk factors and early diagnostic biomarkers of gout renal injury is essential for the prevention and early diagnosis of the disease. This article reviews the research progress in risk factors and early diagnostic biomarkers of gout renal injury.

Protective Effects of Astragaloside IV on Uric Acid-Induced Pancreatic β-Cell Injury through PI3K/AKT Pathway Activation

Background

Elevated uric acid (UA) has been found to damage pancreatic β-cell, promote oxidative stress, and cause insulin resistance in type 2 diabetes (T2D). Astragaloside IV (AS-IV), a major active monomer extracted from Astragalus membranaceus (Fisch.) Bunge. which belongs to TRIB. Galegeae (Br.) Torrey et Gray, Papilionaceae, exhibits various activities in a pathophysiological environment and has been widely employed to treat diseases. However, the effects of AS-IV on UA-induced pancreatic β-cell damage need to be investigated and the associating mechanism needs to be elucidated. This study was designed to determine the protective effects and underlying mechanism of AS-IV on UA-induced pancreatic β-cell dysfunction in T2D.

Methods

UA-treated Min6 cells were exposed to AS-IV or wortmannin. Thereafter, the 3-(45)-dimethylthiahiazo(-z-y1)-35-di-phenytetrazoliumromide (MTT) assay and flow cytometry were employed to determine the effect of AS-IV on cell proliferation and apoptosis, respectively. Insulin secretion was evaluated using the glucose-stimulated insulin secretion (GSIS) assay. Finally, western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to determine the effect of AS-IV on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway in UA-treated cells.

Results

AS-IV had no cytotoxic effects on Min6 cells. UA significantly suppressed Min6 cell growth, promoted cell apoptosis, and enhanced caspase-3 activity; however, AS-IV abolished these effects in a dose-dependent manner. Further, decreased insulin secretion was found in UA-treated Min6 cells compared to control cells, and the production of insulin was enhanced by AS-IV in a dose-dependent manner. AS-IV significantly increased phosphorylated (p)-AKT expression and the ratio of p-AKT/AKT in Min6 cells exposed to UA. No evident change in AKT mRNA level was found in the different groups. However, the effects of AS-IV on UA-stimulated Min6 cells were reversed by 100 nM wortmannin.

Conclusion

Collectively, our data suggest that AS-IV protected pancreatic β-cells from UA-treated dysfunction by activating the PI3K/AKT pathway. Such findings suggest that AS-IV may be an efficient natural agent against T2D.

The Serum Uric Acid to Serum Creatinine Ratio is an Independent Risk Factor for Diabetic Kidney Disease

PURPOSE

A retrospective study was designed to evaluate whether the serum uric acid to serum creatinine ratio (SUA/SCr) can be used as an indicator of diabetic kidney disease (DKD) and macroangiopathy in patients with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

We screened 2227 patients diagnosed with T2DM, and 450 patients were finally included. They were assigned to three groups based on the tertile of SUA/SCr (Group Tertile 1, Tertile 2, Tertile 3). Demographic information and biochemical parameters were collected from Electronic Patient Record (EPR).

RESULTS

The estimated glomerular filtration rate (eGFR) values were lowest in Group Tertile 1 and highest in Group Tertile 3 (P < 0.05). There was no significant difference in urinary albumin creatinine ratio (UACR) among the three groups (P > 0.05). Partial correlation analyses revealed that SUA/SCr levels were significantly and positively correlated with eGFR, SUA, body mass index, gamma-glutamyl transpeptidase, alanine transaminase, triglycerides, C-peptide, high-density lipoprotein cholesterol and fatty liver, while they were negatively correlated with SCr, blood urea nitrogen, cystatin-c, age, male sex, DM duration and hypertension history (P < 0.05). Logistic regression analysis revealed that SUA/SCr was an independent risk factor for eGFR < 60 mL/min/1.73 m² (P < 0.05). The ROC curve showed that the cutoff value of SUA/SCr for the identification of eGFR < 60 mL/min/1.73 m² was 3.434. In patients with normal UACR, SUA/SCr levels of patients with eGFR < 60 mL/min/1.73 m² were lower than those with eGFR ≥ 60 mL/min/1.73 m² (P < 0.05). Regression analysis did not show SUA/SCr associate to macrovascular disease after adjusting for confounding factors.

CONCLUSION

SUA/SCr is an independent risk factor for DKD in patients with T2DM and may be helpful for identifying normoalbuminuric DKD.

Mesenchymal stem cells transplantation attenuates hyperuricemic nephropathy in rats

Mesenchymal stem cells (MSCs), due to their multi-directional differentiation, paracrine and immunomodulation potentials, and the capacity of homing to target organ, have been reported to facilitate regeneration and repair of kidney and improve kidney function in acute or chronic kidney injury. The present study was aimed to evaluate whether MSCs could have a protective effect in hyperuricemic nephropathy (HN) and the underlying mechanisms. A rat HN model was established by oral administration of a mixture of potassium oxonate (PO, 1.5 g/kg) and adenine (Ad, 50 mg/kg) daily for 4 weeks. For MSCs treatment, MSCs (3 × 10⁶ cells/kg per week) were injected via tail vein from the 2nd week for 3 times. The results showed that along with the elevated uric acid (UA) in HN rats, creatinine (CREA), blood urea nitrogen (BUN), microalbuminuria (MAU) and 24-hour urinary protein levels were significantly increased comparing with the normal control rats, while decreased after MSCs treatment. Moreover, the mRNA levels of inflammation and fibrosis-related gene were reduced in UA + MSCs group. Consistently, hematoxylin-eosin (HE) staining results showed the destruction of kidney structure and fibrosis were significantly alleviated after MSCs administration. Similarly, in vitro, NRK-52Es cells were treated with high concentration UA (10 mg/dL) in the presence of MSCs, and we found that MSCs co-culture could inhibited UA-induced cell injury, characterized as improvement of cell viability and proliferation, inhibition of apoptosis, inflammation, and fibrosis. Collectively, MSCs treatment could effectively attenuate UA-induced renal injury, and thus it might be a potential therapy to hyperuricemia-related renal diseases.

Non-Albumin Proteinuria (NAP) as a Complementary Marker for Diabetic Kidney Disease (DKD)

Diabetic kidney disease (DKD) is one of the most common forms of chronic kidney disease. Its pathogenic mechanism is complex, and it can affect entire structures of the kidney. However, conventional approaches to early stage DKD have focused on changes to the glomerulus. Current standard screening tools for DKD, albuminuria, and estimated glomerular filtration rate are insufficient to reflect early tubular injury. Therefore, many tubular biomarkers have been suggested. Non-albumin proteinuria (NAP) contains a wide range of tubular biomarkers and is convenient to measure. We reviewed the clinical meanings of NAP and its significance as a marker for early stage DKD.

The modulatory effects of cinnamaldehyde on uric acid level and IL-6/JAK1/STAT3 signaling as a promising therapeutic strategy against benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a widespread disorder in elderly men. Cinnamaldehyde, which is a major constituent in the essential oil of cinnamon, has been previously reported to reduce xanthine oxidase activity, in addition to its anti-inflammatory, anti-oxidant, and anti-proliferative activities. Our study was designed to investigate the potential modulatory effects of cinnamaldehyde on testosterone model of BPH in rats through reduction of uric acid level, and suppression of IL-6/JAK1/STAT3 signaling pathway. Cinnamaldehyde (40 and 75 mg/kg) was orally administered to male Wistar rats for 3 weeks, and concurrently with testosterone (3 mg/kg, s.c.) from the second week. Cinnamaldehyde ameliorated the elevation in prostatic weight and index compared to rats treated with testosterone only, that was also confirmed by alleviation of histopathological changes in prostate architecture. The protective mechanisms of cinnamaldehyde were elucidated through inhibition of xanthine oxidase activity and reduced uric acid level. That was accompanied by reduction of the pro-inflammatory cytokines; interleukin-6 (IL-6), IL-1β, tumor necrosis factor-alpha (TNF-α), and the nuclear translocation of the transcription factor NF-κB p65, that could be attributed also to the enhanced anti-oxidant defense by cinnamaldehyde. The protein expression of JAK1, which is IL-6 receptor linked protein, was reduced with subsequently reduced activation of STAT3 protein. That eventually suppressed the formation of the proliferation protein cyclin D1, while elevated Bax/Bcl2 ratio. It can be concluded that reducing uric acid level through xanthine oxidase inhibition and suppression of the inflammatory signaling cascade; IL-6/JAK1/STAT3; by cinnamaldehyde could be a novel and promising therapeutic approach against BPH.

Friend or Foe? An Unrecognized Role of Uric Acid in Cancer Development and the Potential Anticancer Effects of Uric Acid-lowering Drugs

In recent years, metabolic syndrome (Mets) has been a hot topic among medical scientists. Mets has an intimate relationship with the incidence and development of various cancers. As a contributory factor of Mets, hyperuricemia actually plays an inseparable role in the formation of various metabolic disorders. Although uric acid is classically considered an antioxidant with beneficial effects, mounting evidence indicates that a high serum uric acid (SUA) level may serve as a pro-oxidant to generate inflammatory reactions and oxidative stress. In this review, we describe the unrecognized role of hyperuricemia in cancer development and summarize major mechanisms linking uric acid to carcinogenesis. Furthermore, we also discuss the potential mechanism of liver metastasis of cancer and list some types of uric acid-lowering agents, which may exert anticancer effects.