A novel method for automated crystal visualization and quantification in murine folic acid-induced acute kidney injury

Citronellol protects renal function by exerting anti-inflammatory and antiapoptotic effects against acute kidney injury induced by folic acid in mice

Acute kidney injury (AKI) is characterized by an abrupt cessation of kidney function. Folic acid-induced renal tubular damage is marked by immense inflammation and apoptosis in the kidney. Citronellol is a type of natural monoterpene alcohol commonly used in traditional medicine. Citronellol possesses pharmacological properties such as antioxidants, anti-inflammatory, and analgesic effects. This study aimed to investigate the reno-protective effect of citronellol against folic acid-induced AKI in mice models. Mice were divided into four groups. In addition to control and AKI-induction groups, two treatment groups were mice that received 50 or 100 mg/kg/day of citronellol orally for four consecutive days. On day 4, mice also received a single injection of folic acid (250 mg/kg) and were euthanized after 48 h. Citronellol 50 and 100 mg/kg rescued renal function as indicated by the significant reduction of serum urea, serum creatinine, and gene expression of KIM-1 compared to the non-treated group. In addition, citronellol 50 and 100 mg/kg relieved renal inflammation by significantly downregulating NF-κB, IL-6, and IL-1β gene expressions compared to the non-treated mice. Furthermore, citronellol retarded renal apoptotic events by the significant decline in renal tissue BAX and cleaved caspase-3 levels compared to non-treated mice. Histopathological report of renal tissue provides further evidence that augments the above results. The study highlighted the importance of some natural compounds that could have a place in therapeutic procedures for kidney injury, as observed by the strong renal protective effects of citronellol against AKI and remarkable anti-inflammatory and antiapoptotic actions.

Animal models to study cognitive impairment of chronic kidney disease

Mild cognitive impairment (MCI) is common in people with chronic kidney disease (CKD), and its prevalence increases with progressive loss of kidney function. MCI is characterized by a decline in cognitive performance greater than expected for an individual age and education level but with minimal impairment of instrumental activities of daily living. Deterioration can affect one or several cognitive domains (attention, memory, executive functions, language, and perceptual motor or social cognition). Given the increasing prevalence of kidney disease, more and more people with CKD will also develop MCI causing an enormous disease burden for these individuals, their relatives, and society. However, the underlying pathomechanisms are poorly understood, and current therapies mostly aim at supporting patients in their daily lives. This illustrates the urgent need to elucidate the pathogenesis and potential therapeutic targets and test novel therapies in appropriate preclinical models. Here, we will outline the necessary criteria for experimental modeling of cognitive disorders in CKD. We discuss the use of mice, rats, and zebrafish as model systems and present valuable techniques through which kidney function and cognitive impairment can be assessed in this setting. Our objective is to enable researchers to overcome hurdles and accelerate preclinical research aimed at improving the therapy of people with CKD and MCI.

Phosphate Restriction Prevents Metabolic Acidosis and Curbs Rise in FGF23 and Mortality in Murine Folic Acid-Induced AKI

SIGNIFICANCE STATEMENT

Patients with AKI suffer a staggering mortality rate of approximately 30%. Fibroblast growth factor 23 (FGF23) and phosphate (P i ) rise rapidly after the onset of AKI and have both been independently associated with ensuing morbidity and mortality. This study demonstrates that dietary P i restriction markedly diminished the early rise in plasma FGF23 and prevented the rise in plasma P i , parathyroid hormone, and calcitriol in mice with folic acid-induced AKI (FA-AKI). Furthermore, the study provides evidence for P i -sensitive osseous Fgf23 mRNA expression and reveals that P i restriction mitigated calciprotein particles (CPPs) formation, inflammation, acidosis, cardiac electrical disturbances, and mortality in mice with FA-AKI. These findings suggest that P i restriction may have a prophylactic potential in patients at risk for AKI.

BACKGROUND

In AKI, plasma FGF23 and P i rise rapidly and are independently associated with disease severity and outcome.

METHODS

The effects of normal (NP) and low (LP) dietary P i were investigated in mice with FA-AKI after 3, 24, and 48 hours and 14 days.

RESULTS

After 24 hours of AKI, the LP diet curbed the rise in plasma FGF23 and prevented that of parathyroid hormone and calcitriol as well as of osseous but not splenic or thymic Fgf23 mRNA expression. The absence of Pth prevented the rise in calcitriol and reduced the elevation of FGF23 in FA-AKI with the NP diet. Furthermore, the LP diet attenuated the rise in renal and plasma IL-6 and mitigated the decline in renal α -Klotho. After 48 hours, the LP diet further dampened renal IL-6 expression and resulted in lower urinary neutrophil gelatinase-associated lipocalin. In addition, the LP diet prevented the increased formation of CPPs. Fourteen days after AKI induction, the LP diet group maintained less elevated plasma FGF23 levels and had greater survival than the NP diet group. This was associated with prevention of metabolic acidosis, hypocalcemia, hyperkalemia, and cardiac electrical disturbances.

CONCLUSIONS

This study reveals P i -sensitive FGF23 expression in the bone but not in the thymus or spleen in FA-AKI and demonstrates that P i restriction mitigates CPP formation, inflammation, acidosis, and mortality in this model. These results suggest that dietary P i restriction could have prophylactic potential in patients at risk for AKI.