Preventive Effect By Novel Curcumin Analog C66of Type1Diabetes-induced Cardiovascular Complications

Background：The development of diabetic cardiovascular complications areattributed to diabetic oxidative stress. Oxidative stress means either over-generation ofreactive oxygen and nitrogen species (ROS/RNS) or down-regulation of antioxidantdefense system in the cell or tissues. Clinical trials with single or even two or threeantioxidants have shown ineffective outcome when were given to diabetic patients.Therefore, to up-regulate endogenous and multiple antioxidants may be a betterapproach for the prevention of diabetic cardiovascular complications. We found thatC66as one of curcumin analogs can effectively inhibit high glucose-inducedinflammatory response and macrophage infiltration, resulting in a significantprevention of renal injury in diabetic rats. Whether C66as a potent antioxidant is ableto prevent diabetes-induced cardiovascular damage via inhibition of JNK function hasnot been addressed yet.Aim：The present study aimed to investigate whether chronic treatment of diabeticmice with C66can prevent the development and/or delay the progression ofdiabetes-induced cardiovascular pathogenesis.Methods: Diabetic model was induced with a single intraperitoneal injection ofstreptozotocin in male C57BL/6mice. Diabetic and age-matched control mice wererandomly divided into three groups which treated with vehicle, C66or JNKi(sp600125). All three kinds of treatments were given by gavage at5mg/kg every otherday for three months. All the blood pressure and cardiac function were assessedbefore diabetes was induced by giving STZ (0M) and the time of animals weresacrificed (3M), respectively. Cardiac inflammation (CD68, MCP-1), fibrosis (CTGF,TGF-β1), oxidative damage（3-NT, MDA）, ER disorders (GRP78，IRE1，ATF4，CHOP, Caspase-12) and apoptosis （BAX/BCL-2， Caspase-3， TUNEL） by siriusred staining, western blot, TUNEL staining, thiobarbituric acid (TBA) assay method.Aortas from these mice were assessed for the inflammation (PAI-1，TNF-α，andp-JNK), oxidative stress (3-NT), fibrosis (Sirius red and mast cell staining), cell apoptosis (TUNEL staining) and proliferation (PCNA staining), Nrf2expression andtranscription and MT expression with immunohistochemical staining or real-timePCR method.Results: Both C66and JNKi prevented the cardiac inflammation, fibrosis, oxidativedamage, ER disorders and apoptosis in type1diabetic mice. C66up-regulatedNFE2-related factor2(Nrf2) expression and transcription activity that was reflectedby increased Nrf2and phosphorylation as well as the expression of Nrf2downstreamantioxidants. And also C66preserve the Metallothionein (MT) expression nearly tocontrol level in diabetic mice. Diabetes significantly increased aortic wall thicknessand structural derangement as well as JNK phosphorylation, all which were attenuatedby C66treatment as JNKi did. Inhibition of JNK phosphorylation by C66and JNKialso significantly prevented diabetes-induced increases in inflammation, oxidative andnitrative stress, apoptosis, proliferation, and fibrosis. Furthermore, inhibition of JNKphosphorylation by C66and JNKi significantly increased aortic Nrf2expression andtranscription function (e.g.: increased expression of Nrf2downstream genes) innormal and diabetic conditions, and aslo preserve the MT expression in diabetic mice.Conclusions: Treatment with C66can prevent or greatly reduce diabetes-inducedcardiac dysfunction, ER stress, cardiac and aortic inflammatory response, oxidativedamage, fibrosis, and cellular apoptosis in diabetic mice. The mechanism responsiblefor this protective effect is mediated by the inhibition of JNK. that may be also relatedto up-regulation of endogenous antioxidants (Nrf2and MT) expression and function.