Combination of aspirin with telmisartan suppresses the augmented TGFbeta/smad signaling during the development of streptozotocin-induced type I diabetic nephropathy.

Diabetic nephropathy (DN) is the most common indication for the development of end stage renal diseases. Inflammation is increasingly seen as the core process in the development of diabetes. Inflammatory markers e.g. NFkappaB (p65 levels), TNFalpha, COX-2 and TGFbeta-smad signaling are the key elements in the development of DN. Renin-angiotensin system suppressors like telmisartan have been used to treat DN, but they are not able to prevent completely because of development of resistance against them. Anti-inflammatory agents like, aspirin acts through both COX dependent and COX independent pathways. Hence, we thought that combining aspirin with telmisartan will be better therapeutic option in preventing the progression of nephropathy in diabetes. In the present study we studied the effect of this combination on inflammatory markers [COX-2, NFkappaB (p65 levels), TNFalpha], TGFbeta-smad expression in preventing the progression of streptozotocin-induced type I diabetic nephropathy. Treatment of aspirin significantly prevented the progression of nephropathy and inhibited the augmented COX-2, NFkappaB (p65 levels), TNFalpha, and TGFbeta-smad expression. Combination of aspirin with telmisartan resulted in a further decrease in the development of nephropathy and inflammatory markers in comparison to aspirin alone treatment. This is the first report which shows that aspirin in combination with telmisartan is more proficient in the treatment of diabetic nephropathy than any single drug therapy and involves the change in expression of inflammatory markers and TGFbeta-smad signaling.

Mulay SR ，Gaikwad AB ，Tikoo K 《-》

Combination therapy with spironolactone and candesartan protects against streptozotocin-induced diabetic nephropathy in rats.

Diabetic nephropathy is one of the most common causes of end-stage kidney disease. Aldosterone and angiotensin II appear to play a crucial role in the pathogenesis of this disease. The present study aimed to investigate effects of the combination therapy with spironolactone and candesartan on diabetic nephropathy and elucidate the underlying mechanism(s) involved. Diabetes was induced in rats by a single intraperitoneal injection of streptozotocin (STZ) (55 mg/kg). The diabetic rats were orally treated with spironolactone (50 mg/kg/day) and/or candesartan (1 mg/kg/day) for 8 weeks. Administration of STZ caused a marked elevation in the serum level of creatinine, urea and urinary albumin-creatinine ratio (ACR). This was associated with upregulated renal protein levels of nuclear factor-kappa B (NF-κB), transforming growth factor (TGF)-β, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) alongside increasing the renal superoxide anion (O2(-)) production, malondialdehyde (MDA) level and the systolic blood pressure. There was a marked decrease in nitric oxide (NO) bioavailability and antioxidant enzyme capacity. The combined therapy of spironolactone and candesartan significantly normalized the oxidative stress and fibrotic/inflammatory alterations. Additionally, the elevated blood pressure was attenuated by administration of candesartan alone or in combination. This was associated with improving the renal function parameters. The combined therapy exhibited more profound response compared to the monotherapy. In conclusion, our results demonstrate that the combined therapy of spironolactone and candesartan can confer an additive benefit over the use of either drug alone against STZ-induced diabetic nephropathy, presumably via attenuating the inflammatory responses and oxidative status markers.

Hofni A ，El-Moselhy MA ，Taye A ，Khalifa MM ... -  《-》

Apigenin ameliorates streptozotocin-induced diabetic nephropathy in rats via MAPK-NF-κB-TNF-α and TGF-β1-MAPK-fibronectin pathways.

Diabetic nephropathy (DN), a microvascular complication of diabetes, has emerged as an important health problem worldwide. There is strong evidence to suggest that oxidative stress, inflammation, and fibrosis play a pivotal role in the progression of DN. Apigenin has been shown to possess antioxidant, anti-inflammatory, antiapoptotic, antifibrotic, as well as antidiabetic properties. Hence, we evaluated whether apigenin halts the development and progression of DN in streptozotocin (STZ)-induced diabetic rats. Male albino Wistar rats were divided into control, diabetic control, and apigenin treatment groups (5-20 mg/kg po, respectively), apigenin per se (20 mg/kg po), and ramipril treatment group (2 mg/kg po). A single injection of STZ (55 mg/kg ip) was administered to all of the groups except control and per se groups to induce type 1 diabetes mellitus. Rats with fasting blood glucose >250 mg/dl were included in the study and randomized to different groups. Thereafter, the protocol was continued for 8 mo in all of the groups. Apigenin (20 mg/kg) treatment attenuated renal dysfunction, oxidative stress, and fibrosis (decreased transforming growth factor-β1, fibronectin, and type IV collagen) in the diabetic rats. It also significantly prevented MAPK activation, which inhibited inflammation (reduced TNF-α, IL-6, and NF-κB expression) and apoptosis (increased expression of Bcl-2 and decreased Bax and caspase-3). Furthermore, histopathological examination demonstrated reduced inflammation, collagen deposition, and glomerulosclerosis in the renal tissue. In addition, all of these changes were comparable with those produced by ramipril. Hence, apigenin ameliorated renal damage due to DN by suppressing oxidative stress and fibrosis and by inhibiting MAPK pathway.

Malik S ，Suchal K ，Khan SI ，Bhatia J ，Kishore K ，Dinda AK ，Arya DS ... -  《-》

Dual therapy versus monotherapy of trandolapril and telmisartan on diabetic nephropathy in experimentally induced type 2 diabetes mellitus rats.

Rao RP ，Jain A ，Srinivasan B 《-》

The combined strategy with PPARα agonism and AT₁ receptor antagonism is not superior relative to their individual treatment approach in preventing the induction of nephropathy in the diabetic rat.

We have previously shown that the low-dose combination of fenofibrate and rosiglitazone might halt the progression of diabetes-induced nephropathy in rats. The present study investigated the combined effect of fenofibrate (PPARα agonist) and telmisartan (AT₁ receptor antagonist) in diabetes-induced onset of nephropathy in rats. The single administration of streptozotocin (STZ, 55 mg/kg i.p.) produced diabetes mellitus, which subsequently produced nephropathy in 8 weeks by markedly elevating serum creatinine, blood urea nitrogen and microproteinuria. In addition, histopathological studies revealed the development of renal structural abnormalities such as mesangial expansion, glomerular and tubular damage. Moreover, diabetes-induced nephropathy was accompanied with high renal oxidative stress and lipid alteration. Treatment with fenofibrate (80 mg/kg/day, p.o., 4 weeks) and telmisartan (10 mg/kg/day, p.o., 4 weeks) either alone or in combination did not affect the elevated glucose levels in diabetic rats. Albeit treatment with fenofibrate normalizes the altered lipid profile in diabetic rats, telmisartan treatment has no effect on it. Treatment with fenofibrate and telmisartan either alone or in combination markedly prevented diabetes-induced onset of nephropathy and renal oxidative stress. Their combination was as good as to their individual treatment, but not superior in attenuating the diabetes-induced nephropathy and renal oxidative stress. It may be concluded that diabetes-induced oxidative stress and lipid alteration, besides hyperglycemia, could play a key role in the induction of nephropathy. Fenofibrate and telmisartan individual treatment was equipotent in preventing the onset of diabetes-induced experimental nephropathy, while their combination did not afford additional benefits in preventing the disease induction of the diabetic kidney.

Bishnoi HK ，Mahadevan N ，Balakumar P 《-》