Ceftriaxone Calcium Crystals Induce Acute Kidney Injury by NLRP3-Mediated Inflammation and Oxidative Stress Injury.

OBJECTIVE: To investigate the role of inflammatory reactions and oxidative stress injury in the mechanisms of ceftriaxone calcium crystal-induced acute kidney injury (AKI) both in vivo and in vitro. METHODS: Male Sprague Dawley rats were randomly divided into five groups of ten each according to different concentrations of ceftriaxone and calcium. Based on the levels of serum creatinine (Scr) and blood urea nitrogen (BUN), the AKI group was chosen for the subsequent experiments. Kidney histological examination and immunohistochemistry were performed. The expression of NLRP3 and IL-1ß protein and the concentrations of oxidative stress markers such as ROS, MDA, and H2O2 in kidney tissues were estimated. In parallel, HK-2 human renal proximal tubule cells were exposed to ceftriaxone calcium crystals. The mRNA expression levels of NLRP3 and IL-1ß and the concentrations of oxidative stress markers were evaluated. Finally, cell viability and rat survival were also assessed. RESULTS: The results showed that significantly increased Scr and BUN levels, consistent with morphological changes and kidney stones, were found in the rats that received the highest concentration of ceftriaxone (1000 mg/kg) combined with calcium (800 mg/kg). The activation of the NLRP3 inflammasome axis and the marked elevation of MDA, H2O2, and ROS levels were observed both in vivo and in vitro. High expression of Nrf2, HO-1, and NQO1 was also documented. In addition, cell apoptosis and rat mortality were promoted by ceftriaxone calcium crystals. CONCLUSIONS: Notably, we found that ceftriaxone-induced urolithiasis was associated with a high risk of AKI and NLRP3-mediated inflammasome and oxidative stress injury were of major importance in the pathogenesis.

Protective effect of salvianolic acid B against oxidative injury associated with cystine stone formation.

The aim of this study was to investigate the role of oxidative stress in cystine crystal formation and whether salvianolic acid B, a natural antioxidant, could prevent cystine-mediated oxidative injury in vivo and in vitro. The levels of oxidative stress and antioxidase activity in cystine stone patients were assessed. Then, the oxidative stress exerted by cystine on human kidney-2 (HK-2) cell viability and biochemical parameters including antioxidase activity and antioxidant protein expression were evaluated, and the protective action of salvianolic acid B was also examined. Finally, salvianolic acid B was tested to determine whether it could prevent or reduce renal crystal formation in Slc7a9 knockout mice. The activity levels of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were decreased, and the amount of malondialdehyde (MDA) was increased in patients with cystine stones compared with people without cystine stones (p < 0.05). Significant reductions in cell viability, antioxidase activity and antioxidant protein expression levels were found in the cystine group compared with controls. However, such oxidative injuries were prevented by salvianolic acid B. In the animal study, loose crystals with white spots were seen in the renal parenchyma, bilateral renal pelvis and bladders in the Slc7a9 knockout group. In contrast, no renal crystals were seen in the control group, and markedly fewer crystals with significantly higher antioxidase activity and diminished oxidative stress were detected in the salvianolic acid B group. Cystine cytotoxicity in vitro and cystine stone formation in vivo were associated with oxidative stress, and salvianolic acid B could protect against cystine stone-induced injury.

Erythropoietin mobilizes renal progenitor cells to reduce ischemic reperfusion injury in rats with nephron-sparing surgery / 中华肾脏病杂志

Objective To investigate the effects of the erythropoietin (EPO) on ischemia reperfusion injury (IRI) in rats with nephron-sparing surgery (NSS). Methods Fifty-four Sprague Dawley rats were divided into 3 groups randomly after right kidney nephrectomy: Sham group, NSS group (PBS+NSS) and EPO group (EPO+NSS). During NSS, renal artery was clamped for 40 min to induce IRI. Sham group just adopted exposure renal artery without vascular clamped. Rats in NSS group were injected intraperitoneally with PBS for 3 days before NSS. Rats in EPO group were injected intraperitoneally with EPO for 3 days before NSS. After 12 h, 24 h, 72 h, blood sample and renal tissues were collected. The serum creatinine (Scr) and urea nitrogen (BUN) were evaluated. The pathology injury was evaluated by HE staining. The CD24/CD133 double-positived renal progenitor cells (RPCs) were tested by flow cytometry. The CD133 and PCNA protein were quantified by immunohistochemical staining. The expressions of Wnt7b and β-catenin protein were detected by Western blotting. Results Rats in NSS group had more elevated Scr, BUN and pathology injury scores 12 h, 24 h and 72 h after operation than those in Sham group (all P<0.05). Compared with those in the NSS group, the Scr and BUN in the EPO group were significantly lower 24 h after the surgery (all P<0.05), and the pathology injury score also decreased (P<0.05). The proportion of RPCs, expressions of CD133 and PCNA, and expressions of Wnt7b and β-catenin protein were significantly higher after 24 h of the surgery in NSS group than those in the Sham group (all P<0.05). While compared with those in the NSS group, the proportion of RPCs and expressions of CD133, PCNA, Wnt7b and β-catenin increased at the EPO group (all P<0.05). Conclusions EPO can reduce the IRI after NSS, and its mechanism may be related to the mobilization of the RPCs by the Wnt7b/β-catenin signal pathway.