Combined Clopidogrel And Irbesartan Therapy Attenuated The Renal Disease Progression In Rats With 5/6 Nephrectomy

Background and Objective: Diffuse glomerular sclerosis and interstitial fibrosis contribute to the progression of renal damage and are the final common pathway for almost all forms of kidney diseases. Whatever the initial injury, the remaining nephrons undergo adaptive hypertrophy and hyperfiltration that minimize the functional consequences of the progressive nephron loss. However, the adaptation ultimately leads to a vicious cycle in which hyperfiltration of the remaining nephrons impairs glomerular barrier, which in turn induces tubulointerstitial damage and then results in the loss of more nephrons. In recent years, more attention has been focused on the inflammatory infiltration present in various types of progressive renal diseases in humans and in experimental models. The number of inflammatory cells in the renal interstitium closely correlates with the severity of glomerular and tubulointerstitial lesions and with loss of renal function. Inflammatory cells and activated intrinsic kidney cells can produce various cytokines, which can promote the progress of glomerular sclerosis and interstitial fibrosis. Mounting evidences have shown that platelet activation, and especially activation of the renin-angiotensin-system (RAS), were shown to promote glomerular inflammation and fibrosis, and play a pivotal role in the progression of chronic kidney diseases (CKD). Thus, we hypothesized that CLO or an ARB, irbesartan (IRB), could attenuate the progression of chronic renal disease through its suppression on inflammation, cell transdifferentiation, and fibrosis. Meanwhile, we compared the effects of combining CLO with IRB, versus either drug alone on the renal disease progression in this rat model.Materials and Methods: Male Wistar rats were subject to 5/6 renal ablation by two-step operation and the 48 survival rats were randomly assigned to 4 groups: untreated group (NX group), clopidogrel treated group (CLO group, 20mg/kg/d), irbesartan treated group (IRB group, 20mg/kg/d), and clopidogrel plus irbesartan treated group (CLO/IRB group, 20mg/kg/d plus 20mg/kg/d). Sham-operated ratssevered as controls (SHM group). Distilled water or medicine was administrated respectively by gavage during the period of 8 weeks. The general status, body weight, systolic blood pressure, proteinuria (24hUP), serum creatinine (Scr), and the weight of remnant kidney were measured. Glomerular and tubulointerstitial histological damage scores were also measured. Additionally, we detected the protein and/or mRNA expression of ED-1, a-smooth muscle actin (a-SMA), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), transforming growth factor-|31 (TGF-Pi) and connective tissue growth factor (CTGF) in 5 groups by Northern blot, Western blot and immunohistochemistry.Results: At the end of 8 week treatment, Compared to NX group, CLO group or IRB group reduced 24hUP and Scr, IRB group was more effective than CLO group (P<0.05). Compared to single CLO or IRB group, CLO/IRB treated group was more effective. Compared to NX group, CLO/IRB treated group showed significantly smaller scores of glomerular sclerotic index (0.59±0.21 vs. 1.63±0.75, P<0.05) and tubulointerstitial histological damage ( 0.41±0.35 vs. 1.89±0.65, PO.05 ) at 8th week. The mean glomerular sectional area was also lower than that in the NX group. Compared to single CLO group or IRB group, combination therapy was more effective in attenuating renal damage.Compared with NX group, CLO/IRB decreased the number of ED-l(3.09±0.35 vs. 28.54±0.41, P<0.05) and down-regulated the expression of a-SMA, MCP-1, ICAM-1, also inhibited the expression of TGF-pK CTGF. Compared to single clopidogrel or irbesartan, combination therapy was more effective in reducing the protein or mRNA levels of MCP-1, ICAM-1, TGF-pi and CTGF (i><0.05).Conclusion: CLO/IRB can inhibit the compensatory hyperplasia and slow the progression of chronic renal injury through non-hemodynamic mechanism such as inhibition of the inflammation cells infiltration and expression of cytokines in the remnant kidney, thus inhibit renal fibrosis. Compared to single clopidogrel or irbesartan, combination therapy was more effective.