Westernized societies are experiencing an epidemic of type II diabetes (T2DM), related to life-style, obesity, and longevity. T2DM is a systemic vascular disorder; wide-spread low grade arterial inflammation, elevated TNF-alpha levels, & oxidative stresses disrupt macrovascular (e.g., heart, aorta) & microvascular (e.g. retina, renal glomerulus) functions. A highly characteristic feature of T2DM is medial artery calcification (MAC). The negative consequences of reduced aortofemoral compliance of MAC have emerged; MAC perturbs normal Windkessel physiology, causing systolic & diastolic dysfunction that increases mortality & amputation risk. The ability to prevent or treat MAC represents an unmet clinical need. A better understanding of how diabetes and kidney disease (CKD) promote MAC will provide insights useful for devising new strategies to reduce vascular calcium load, preserve aortic compliance, & improve vascular function. Recent data have identified activated aortic BMP2-Msx2-Wnt signaling in diabetic MAC--all inhibited by infliximab. The chief goal of this project is to assess how targeting these signals can improve aortic calcification, structure, & compliance.
Aim 1 : """"""""To test whether inhibition of arterial BMP2- Wnt induction with theTNF-alpha antagonist infliximab or salicylate improves aortic compliance in diabetic vascular disease."""""""" By assessing aortic pressure- diameter relationships using ex vivo video plethysmography, we will establish the relationships between TNF-alpha & aortic calcium accumulation, Wnt signaling, and stiffness in a relevant T2DM model--the TOPGAL+; LDLR-/- mouse fed diabetogenic high fat diets (HFD). Comparison will be made with responses to the RANKL inhibitor, OPG.
Aim 2 : """"""""To characterize the mechanisms whereby TNF- alpha signaling via NADPH oxidase promotes Msx2 gene transcription in aortic adventitial myofibroblasts."""""""" The NAPDH oxidase inhibitor, apocynin, inhibits Msx2 induction by TNF-alpha (transcriptionally mediated). By identifying the signaling cascades conveying Msx2 induction in response to TNF-alpha, novel strategies can be devised to inhibit vascular calcification.
Aim 3 : """"""""To identify if NADPH oxidase signaling is required for induction of aortic BMP2-Msx-2-Wnt cascades in T2DM, using p47phox- /-; TOPGAL+; LDLR-/- mice as a model."""""""" By phenotyping p47phox-/-; TOPGAL+; LDLR-/- and p47phox+/-;TOPGAL+; LDLR-/- controls, we assess whether this TNF- regulated redox pathway contributes to aortic BMP2-Msx2-Wnt activation by HFD. ? ? ?
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