Lee SW, et al. J Korean Med Sci. 2017 Nov;32(11):1800-1806. https://doi.org/10.3346/jkms.2017.32.11.1800

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.

The immunosuppressive drug tacrolimus has the short-term effect of reducing proteinuria in patients with immunoglobulin A nephropathy (IgAN). Our study investigated the effects on proteinuria and kidney function after discontinuation of tacrolimus. Patients with biopsy-proven IgAN were included in the study and randomly divided into two treatment groups. There was a corresponding control group for each treatment group. The first group included patients treated with tacrolimus (Tac vs non-Tac group) and the second group included patients with a renin angiotensin system blocker (RASi vs non-RASi group). The Tac group received treatment for up to 16 weeks, with the administration of tacrolimus being ceased at the final visit (trial phase). We tracked the patients at 12, 24, 52, and 240 weeks (observational phase). The primary outcomes examined were the percentage change (from the trial phase to the observational phase) of time-averaged proteinuria (TA-proteinuria; g/g creatinine [cr]) and the estimated glomerular filtration rate (eGFR). Time-averaged proteinuria was defined as the average of urine protein to creatinine ratio (UPCR), measured every 3 months during both the trial and observational phases of the study. A significant reduction in UPCR was observed in the Tac group compared to non-Tac group at the 4 and 8 week visits during the trial phase (p = 0.023 and p = 0.003, respectively). However, the difference between the Tac group and non-Tac group was not evident in the other review periods, estimated by linear mixed effect model. The percentage change in TA-proteinuria was greater in the Tac group than that in the corresponding control group (116 ± 96% vs. 63 ± 239%, p = 0.004). Therefore, during the observational phase, TA-proteinuria was not significantly different between the Tac group and the non-Tac group (1.150 ± 0.733 g/g cr vs. 1.455 ± 2.017 g/g cr, p = 0.775). The levels of eGFR throughout the observational phase were not significantly different between the two groups. Furthermore, the mean rate of eGFR change throughout both phases of the study was -6.4 ± 5.9 mL/min/1.73 m²/year in the non-Tac group and -5.4 ± 7.9 mL/min/1.73 m²/year in the Tac group (p = 0.988). The anti-proteinuric effect of tacrolimus was promptly reversed 3 months after discontinuing the drug. The use of tacrolimus for a short period of time for patients with IgAN temporarily reduces proteinuria, but the data showed no long-term efficacy regarding proteinuria reduction and improvement of renal function.

So D, et al. J Korean Med Sci. 2022 May;37(19):e154. https://doi.org/10.3346/jkms.2022.37.e154

This study investigated the role of the axis involving chemokine receptor 6 (CCR6) and its ligand chemokine (C–C motif) ligand 20 (CCL20) in acute kidney disease (AKD) using an ischemia–reperfusion injury (IRI) model. The model was established by clamping the unilateral renal artery pedicle of C57BL/6 mice for 30 min, followed by evaluation of CCL20/CCR6 expression at 4 weeks post‐IRI. In vitro studies were conducted to examine the effects of hypoxia and H ₂ O ₂ ‐induced oxidative stress on CCL20/CCR6 expression in kidney tissues of patients with AKD and chronic kidney disease (CKD). Tubular epithelial cell apoptosis was more severe in C57BL/6 mice than in CCL20 antibody‐treated mice, and CCR6, NGAL mRNA, and IL‐8 levels were higher under hypoxic conditions. CCL20 blockade ameliorated apoptotic damage in a dose‐dependent manner under hypoxia and reactive oxygen species injury. CCR6 expression in IRI mice indicated that the disease severity was similar to that in patients with the AKD phenotype. Morphometry of CCL20/CCR6 expression revealed a higher likelihood of CCR6 ⁺ cell presence in CKD stage 3 patients than in stage 1–2 patients. Kidney tissues of patients with CKD frequently contained CCL20 ⁺ cells, which were positively correlated with interstitial inflammation. CCL20/CCR6 levels were increased in fibrotic kidneys at 4 and 8 weeks after 5/6 nephrectomy. These findings suggest that modulating the CCL20/CCR6 pathway is a potential therapeutic strategy for managing the progression of AKD to CKD.