Expression of erythropoietin and its receptor in kidneys from normal and cyclosporine-treated rats.

Long-term treatment with cyclosporine A (CsA) is associated with various types of complications; however, CsA-induced anemia has not been reported. The present study examined the impact of CsA on hematopoietic parameters and intrarenal expression of erythropoietin (EPO) and the EPO receptor (EPOR) in a rat model of chronic CsA nephrotoxicity. Sprague-Dawley rats were fed a low-salt diet (0.05% sodium) and were treated daily for 4 weeks with vehicle (olive oil 1 mL/kg subcutaneously) or CsA (15 mg/kg subcutaneously). The expression of EPO and EPOR was evaluated by immunohistochemistry and immunoblotting, and hematopoietic parameters were assessed by measuring blood hemoglobin and hematocrit levels, and these variables were compared between treatment groups. Renal function, oxidative stress, histopathology (tubulointerstitial fibrosis), apoptotic cell death, and expression of transforming growth factor ß-inducible gene-h3 (ßig-h3) were also compared between treatment groups. In kidneys from vehicle-treated rats, endogenous EPO and EPOR protein were expressed constitutively in the outer stripe of the outer medulla and the cortex. EPO protein expression decreased significantly in kidneys from CsA-treated rats. By contrast, EPOR expression was higher in kidneys from CsA-treated rats than in vehicle-treated rats. These changes were accompanied by decreases in serum hemoglobin and hematocrit levels and correlated with the number of cells positive for terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (r = -0.769, P = .003) and ßig-h3 protein expression (r = -0.910, P < .001). Long-term treatment with CsA suppresses renal endogenous EPO expression, resulting in anemia. Increases in apoptotic cell death and ßig-h3 expression are closely associated with inhibition of EPO expression in chronic CsA nephrotoxicity.

L-carnitine protects against cyclosporine-induced pancreatic and renal injury in rats.

BACKGROUND: L-carnitine has protective effects against various types of injury. This study was designed to evaluate the beneficial effects of L-carnitine on pancreatic and renal injuries caused by cyclosporine (CsA). METHODS: Rats maintained on a low sodium diet were given vehicle (olive oil, 1 mL/kg/d), CsA (15 mg/kg/d), L-carnitine (50 or 200 mg/kg/d), or a combination of CsA and L-carnitine for 4 weeks. The impact of L-carnitine on pancreatic injury was assessed by blood glucose levels, plasma insulin concentrations, and hemoglobulin A1c (HbA1c). In addition, the protective effects of L-carnitine against CsA-induced kidney injury were evaluated in terms of renal function, histopathology (inflammatory cell influx and tubulointerstitial fibrosis), oxidative stress (8-hydroxy 2'-deoxyguanosine, 8-OHdG), transforming growth factor-betal (TGF-ß1), apoptosis (caspase-3), and autophagy (LC3-II). RESULTS: CsA treatment caused diabetes, renal dysfunction, tubulointerstitial inflammation (ED-1-positive cells), and fibrosis, which were accompanied by an increase in 8-OHdG production and upregulation of TGF-ß1, caspase-3, and LC3-II. Concomitant administration of L-carnitine increased plasma insulin concentrations, decreasing plasma glucose and HbA1c levels. In the kidney, L-carnitine induced dose-dependent improvement of renal function, inflammation, and fibrosis in parallel with suppression of the expression of TGF-ß1 and 8-OHdG. Furthermore, the administration of L-carnitine at a high dose inhibited the expression of caspase-3 and LC3-II. CONCLUSION: These findings suggest that L-carnitine has a protective effect against CsA-induced pancreatic and renal injuries.

Protective effect of paricalcitol on cyclosporine-induced renal injury in rats.

We evaluated the protective effect of paricalcitol on cyclosporine (CsA)-induced renal injury using an experimental model of chronic CsA nephropathy. Paricalcitol (50 and 200 ng/kg/d) was concomitantly administered with CsA (15 mg/kg/d) for 28 days in rats. We assessed the effects of paricalcitol by measuring degree of the tubulointerstitial fibrosis (TIF) and inflammation, a profibrotic cytokine (ßig-h3), a proapoptotic gene (caspase-3), apoptotic cell death, and oxidative stress. The CsA-treated rats showed increased TIF and inflammatory cell infiltration, but paricalcitol treatment (200 ng/kg) significantly decreased those compared with the CsA-alone group. The expression of ßig-h3, a biologic marker of transforming growth factor ß1, which was increased in the CsA group, also decreased with paricalcitol treatment. The increased rates of excretion of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and expression of tissue 8-OHdG produced by CsA treatment were significantly attenuated by paricalcitol treatment. The increased expression of caspase-3 and number of TUNEL-positive cells in the CsA group were decreased with concomitant paricalcitol treatment. The effect of paricalcitol was more evident high among the rather than low-dose cohort. In conclusion, paricalcitol showed antiinflammatory and antifibrotic effects. This finding may provide a rationale for use of paricalcitol in CsA-induced renal injury.

Influence of sirolimus on cyclosporine-induced pancreas islet dysfunction in rats.

This study was performed to investigate the effect of sirolimus (SRL) on cyclosporine (CsA)-induced pancreatic islet dysfunction in rats. Three separate studies were performed. First, diabetogenic effect of SRL was evaluated with three different doses (0.15, 0.3 and 0.6 mg/kg). Second, rats were treated with SRL (0.3 mg/kg) with or without CsA (15 mg/kg) for 4 weeks. Third, rats were treated with CsA for 4 weeks, and then switched to SRL for 4 weeks. The effect of SRL on CsA-induced pancreatic islet dysfunction was evaluated by an intraperitoneal glucose tolerance test, plasma insulin concentration, HbA1c level, HOMA-R index, immunohistochemistry of insulin and pancreatic beta islet cell mass. The SRL treatment increased blood glucose concentration in a dose-dependent manner. The combined treatment with SRL and CsA increased blood glucose concentration, Hemoglobin A1c (HbA1c) level, HOMA-R [fasting insulin (mU/mL) x fasting glucose (mmol/L)]/22.5] index and decreased plasma insulin concentration, immunoreactivity of insulin and pancreatic beta islet cell mass compared with rats treated with CsA. CsA withdrawal for 4 weeks improved pancreatic beta-cell function and structure. However, conversion from CsA to SRL further increased blood glucose levels compared with the rats converted from vehicle to SRL. The results of our study demonstrate that SRL is diabetogenic and aggravates CsA-induced pancreatic islet dysfunction.