Research Progress in Acute Hypertensive Renal Injury by "in Vivo Cryotechnique"

Insights into the complex relationship between triglyceride glucose-waist height ratio index, mean arterial pressure, and cardiovascular disease: a nationwide prospective cohort study

BACKGROUND

Both the triglyceride glucose-waist height ratio (TyG-WHtR) index and elevated arterial blood pressure are risk factors for cardiovascular disease (CVD). However, it is uncertain whether the TyG-WHtR index can increase the risk of CVD by influencing arterial blood pressure, and the extent to which the TyG-WHtR index may mediate the association between arterial blood pressure and CVD. The purpose of this study is to evaluate complex association of the TyG-WHtR index and mean arterial pressure (MAP) with CVD.

METHODS

All data in this study were obtained from the China Health and Retirement Longitudinal Study (CHARLS) free of CVD at baseline. CVD was defined as self-reporting heart disease and stroke. Cox proportional hazards model and restricted cubic spline (RCS) were used to analyze the association of the TyG-WHtR index and MAP with the risk of CVD. Time-dependent receiver operating characteristic (ROC) analysis was used to assess the predictive performance of TyG-WHtR, MAP for CVD. Four-way decomposition method explored the mediating effects of the TyG-WHtR index and MAP in CVD.

RESULTS

A total of 7976 participants were included in this study. The mean age of the participants was 58.68 ± 9.60 years, and 4263 (53.45%) were females. During a maximum follow-up of 7.0 years, 1326 (16.62%) people developed CVD. Both the TyG-WHtR index and MAP were signifcantly associated with CVD. The RCS regression analyses demonstrated a positive linear association of the TyG-WHtR index and MAP with the incidence of CVD. Compared with participants with TyG-WHtR < median and MAP < median, those with TyG-WHtR ≥ median and MAP ≥ median had the highest risk of CVD (HR 1.961; 95%CI 1.660-2.317). The combination of TyG-WHtR and MAP demonstrated incremental predictive utility over either biomarker alone, as evidenced by improvements in integrated discrimination improvement (IDI) and net reclassification improvement (NRI). While absolute predictive performance remained moderate. Increased MAP signifcantly mediated 52.43% of the associations between TyG-WHtR index and CVD, and increased TyG-WHtR index signifcantly mediated 83.40% of the associations between MAP and CVD.

CONCLUSION

The combination of a higher TyG-WHtR index and a higher MAP was associated with the highest risk of CVD. The combined model of the TyG-WHtR index and MAP showed improved predictive ability, as indicated by IDI and NRI, although its overall predictive performance was still moderate. The MAP could partially mediate the association between TyG-WHtR index and CVD, as well as TyG-WHtR index could also partially mediate the association between MAP and CVD. These findings suggested that the combination of TyG-WHtR index and MAP helps identify populations at early risk of CVD and improve risk stratifcation.

Cordyceps sinensis extract protects against acute kidney injury by inhibiting perforin expression in NK cells via the STING/IRF3 pathway

Acute kidney injury (AKI) is associated with immune cell activation and inflammation. However, the putative pathogenic mechanisms of this injury have not been thoroughly investigated. Natural killer (NK) cells play an important role in immune regulation; however, whether NK cells regulate AKI remains unclear. Cordyceps sinensis (CS), a modern Chinese patented medicine preparation, has been widely used in treating patients with chronic kidney disease (CKD) owing to its anti-inflammatory effects and maintenance of immune homeostasis. Whether 2'-deoxyadenosine, a major active component in CS, can ameliorate renal AKI by regulating immunity, particularly in NK cells, has not been reported. This study is the first to demonstrate how NK cells promote AKI by releasing perforin, interferon-gamma (IFN-γ) and other inflammatory factors in vivo and in vitro. Differential gene expression between AKI and normal tissues was assessed using bioinformatic analyses. Quantitative real-time PCR, western blotting, and immunohistochemical staining were used to detect target protein mRNA and protein expression. Levels of inflammatory factors were measured using enzyme-linked immunosorbent assay. We found the high doses of the 2'-deoxyadenosine treatment significantly alleviated FA-induced renal damage in vivo, and alleviated the NK cells of renal injury by activating the STING/IRF3 pathway to inhibit perforin release in vitro. The results showed that 2'-deoxyadenosine could mitigate AKI by downregulating the activity of NK cells (by decreasing the expressions of perforin and IFN-γ) and inhibiting the stimulator of interferon genes and phosphorylated IFN regulatory factor 3. This may provide valuable evidence supporting the clinical use of CS in treating patients with AKI.

URINARY NEPHRIN AS AN EARLY BIOMARKER OF HYPERTENSIVE NEPHROPATHY

Hypertensive nephropathy (HN) is characterized by kidney damage due to chronic high blood pressure. Podocytes play a crucial role in the pathogenesis of HN, thus, nephrin could be important in the early diagnosis of HN. The aim of the study was to investigate the association of urinary nephrin (u-nephrin) levels with clinical and laboratory characteristics in patients with HN and to test diagnostic relevance of u-nephrin as an early biomarker of HN. In this cross-sectional study, 114 subjects were recruited, 84 patients with chronic hypertension (CH) and 30 healthy controls. All patients with CH were classified according to the urinary microalbumin/creatinine ratio (UM/CR) and according to the chronic kidney disease (CKD) stage. Urine samples were collected to estimate the u-nephrin level by ELISA and to determine UM/CR. Blood samples were used for biochemical analyses. We found elevated u-nephrin in 78.3% of normoalbuminuric subjects with CH. The levels of u-nephrin increased gradually with the stage of CKD. ROC curve plotted for u-nephrin showed 89.7% sensitivity and 88.8% specificity, while UM/CR showed a sensitivity of 44.8% and specificity of 86.1% to detect HN in the early stage. It is concluded that u-nephrin can be useful as an early biomarker of HN.

Renoprotective Effect of KLF2 on Glomerular Endothelial Dysfunction in Hypertensive Nephropathy

Kruppel-like factor 2 (KLF2) regulates endothelial cell metabolism; endothelial dysfunction is associated with hypertension and is a predictor of atherosclerosis development and cardiovascular events. Here, we investigated the role of KLF2 in hypertensive nephropathy by regulating KLF2 expression in human primary glomerular endothelial cells (hPGECs) and evaluating this expression in the kidney tissues of a 5/6 nephrectomy mouse model as well as patients with hypertension. Hypertension-mimicking devices and KLF2 siRNA were used to downregulate KLF2 expression, while the expression of KLF2 was upregulated by administering simvastatin. After 4 mmHg of pressure was applied on hPGECs for 48 h, KLF2 mRNA expression decreased, while alpha-smooth muscle actin (αSMA) mRNA expression increased. Apoptosis and fibrosis rates were increased under pressure, and these phenomena were aggravated following KLF2 knockdown, but were alleviated after simvastatin treatment; additionally, these changes were observed in angiotensin II, angiotensin type-1 receptor (AT1R) mRNA, and interleukin-18 (IL-18), but not in angiotensin type-2 receptor mRNA. Reduced expression of KLF2 in glomerular endothelial cells due to hypertension was found in both 5/6 nephrectomy mice and patients with hypertensive nephropathy. Thus, our study demonstrates that the pressure-induced apoptosis and fibrosis of glomerular endothelial cells result from angiotensin II, AT1R activation, and KLF2 inhibition, and are associated with IL-18.