A Novel Dipeptidyl Peptidase-4 Inhibitor DA-1229 Ameliorates Tubulointerstitial Fibrosis in Cyclosporine Nephrotoxicity in Mice

Cyclosporine A (CyA) is an immunosuppressive agent that induces nephrotoxicity with long-term treatment. The roles of DPP-4 and its inhibitors in cyclosporine nephrotoxicity are not fully understood. Therefore, we investigated the effects of a novel DPP-4 inhibitor, DA-1229, on the progression of renal disease in an experimental cyclosporine nephrotoxicity model. Chronic cyclosporine nephrotoxicity was induced in six-week-old male ICR mice by subcutaneous injections of CyA at a dose of 30 mg/kg for four weeks. Animals were treated with DA-1229 at a dose of 300 mg/kg per day in food for four weeks. Although DPP-4 activity did not increase in the kidneys of mice with induced cyclosporine nephrotoxicity, DA-1229 treatment significantly suppressed DPP-4 activity in both plasma and renal tissues. DPP-4 inhibition by DA-1229 led to significantly decreased albuminuria and urinary excretion of 8-isoprosatane. DPP-4 inhibition also substantially suppressed pro-inflammatory effects, profibrotic molecules, and macrophage infiltration, and led to the improvement in renal structural changes. Our results suggest that DPP-4 inhibition by DA-1229 provides renoprotective effects in an animal model of cyclosporine nephrotoxicity via antioxidant, anti-inflammatory, and anti-fibrotic mechanisms. DPP-4 inhibition may be a useful new therapeutic approach for the management of progressive renal disease in cyclosporine nephrotoxicity.

Effect of Fosfomycin on Cyclosporine Nephrotoxicity

Fosfomycin (Fos) has emerged as a potential treatment against multidrug-resistant organisms, however, there has been little work done on its influence on calcineurin inhibitor nephrotoxicity (CIN). This study was designed to evaluate the effect of Fos in combination with cyclosporine (CsA) on CIN. Two sets of experiments were undertaken. In the first, Wistar rats received different doses of Fos: 0, 62.5, 125, 250, and 500 mg/kg. In the second, rats were divided into four groups: control, CsA 15 mg/kg s.c., CsA + fosfomycin 62.5 mg/kg (CsA + LF), and CsA + Fos 500 mg/kg (CsA + HF). CsA was administrated daily for 14 days, whereas Fos administration started on the ninth day followed by two more doses, delivered 48 h apart. The administration of different Fos doses did not alter renal function. In contrast, CsA induced arteriolopathy, hypoperfusion, a reduction in the glomerular filtration rate, and downregulation of eNOS, angiotensinogen, and AT1R mRNA levels. Lower doses of Fos did not modify CIN. Instead, the CsA + HF group exhibited greater hypoperfusion, arteriolopathy, and oxidative stress, and increased mRNA levels of pro-inflammatory cytokines. This study shows that Fos administered by itself at different doses did not cause renal injury, but when it was given repeatedly at high dosages (500 mg/kg) in combination with CsA, it increased CIN through the promotion of greater oxidative stress and renal inflammation.

LONG-TERM FUNCTIONING OF KIDNEY GRAFTS

Purpose of the study. To study the morphological changes of long-functioning kidney transplants and determine the main causes of transplant dysfunction. Materials and methods. A total of 52 recipients aged 20 to 70 years were analyzed retrospectively at different times after transplant surgery (5 to 22 years).Morphological changes in the kidney transplant are comparable according to light microscopy. The morphological changes in the graft were studied in the initial and long-term period. Morphological studies were conducted in monitoring mode. Results. In the early period after transplantation, ischemic injuries, primary graft function, and episodes of acute rejection were taken into account. In the distant period, morphological changes were evaluated in accordance with the recommendations of the Banff-classification.When analyzing long-term results, antigen- dependent (immune) and antigen-independent (visible) factors that affect the renal transplant are distinguished. The main clinical and laboratory indicators of allografts dysfunction are increased creatinine and proteinuria.In antigen-dependent forms (cellular, humoral and mixed rejection), humoral rejection is the most common (25%) allografts dysfunction.Antigen-independent forms of dysfunction (streptococcal infection 25%, inflammatory diseases 19,2%, recurrent pathology 3,8%, signs of cyclosporine nephrotoxicity in combination with other forms was found in 59,2%, nephrosclerosis 65,4%). Conclusions. The data obtained suggest that antigen-dependent (immune) factors, and in particular humoral rejection, are the most common cause of allografts dysfunction, and antigen- independent factors contribute to the progression of chronic rejection and the development of nephrosclerosis. Keywords: renal transplant, antigen-dependent, antigen-independent, dysfunction.

Molecular basis of the counteraction by calcium channel blockers of cyclosporine nephrotoxicity

Nephrotoxicity is a serious side effect for the immunosuppressant drug cyclosporine A(CSA). In this study, we tested the hypothesis that administration of calcium channel blockers such as verapamil or nifedipine ameliorates renal CSA-induced renal dysfunction. Furthermore, our study investigates the roles of inflammatory, oxidative, and fibrotic pathways in CSA-induced renal dysfunction. Six groups of male rats ( n = 6/group) were used and received one of the following treatments for seven consecutive days: vehicle (Cremophor EL ip), CSA (25 mg·kg−1·day−1 ip), verapamil (2 mg·kg−1·day−1 ip), nifedipine (3 mg·kg−1·day−1 ip), CSA in the presence or absence of either verapamil, or nifedipine. Biochemical and histomorphometric analyses showed that rats treated with CSA exhibited clear signs of nephrotoxicity that included 1) proteinuria and elevations in serum creatinine and blood urea nitrogen, 2) mesangial expansion, 3) increases in glomerular and tubular type IV collagen expression, and 4) increases in the glomerulosclerosis and tubulointerstitial fibrosis indices. Although the single administration of nifedipine or verapamil had no significant effect on renal pathology, or its biochemical and physiological function, the concurrent use of either calcium channel blockers significantly and equipotently ameliorated the biochemical, morphological, and functional derangements caused by CSA. More importantly, we report that the oxidative (reactive oxygen species production, NADPH-oxidase activity, and dual oxidase 1/2 levels), fibrotic (transforming growth factor-β1 expression), and inflammatory (NF-κB expression) manifestations of renal toxicity induced by CSA were significantly reversed upon administration of nifedipine or verapamil. Together, these results highlight the efficacy of calcium channel-blocking agents in attenuating CSA-induced nephrotoxicity and predisposing biochemical and molecular machineries.

Colchicine in Renal Medicine: New Virtues of an Ancient Friend

Colchicine is a plant-derived alkaloid that disrupts the cell microtubule system and accumulates in neutrophils, inhibiting neutrophil adhesion and recruitment. Colchicine has been used extensively in the prevention and treatment of gouty arthritis attacks, familial Mediterranean fever attacks and resultant AA amyloidosis, and recurrent pericarditis. Colchicine also disrupts the intracellular traffic of additional inflammatory and fibrosis mediators. Renal fibrosis is the final common pathway of chronic renal disease. Colchicine had anti-fibrotic effects in experimental diabetic nephropathy, renal mass reduction, and cyclosporine nephrotoxicity among others and is undergoing clinical trials for non-diabetic metabolic syndrome and diabetic nephropathy. In this review, we summarize the anti-inflammatory and anti-fibrotic properties of colchicine in experimental and clinical studies in renal diseases or other fibrotic disease processes with renal consequences. We also discuss the potential future uses of colchicine in renal medicine and challenges faced with its use in patients with impaired kidney function.