Background: Plasma advanced glycation end products (AGEs) activates the receptor for advanced glycation end products (RAGE) and the activation of RAGE is implicated to be the pathogenesis of type 2 diabetic mellitus patient vascular complications. Attenuating the activation of RAGE may exert a protective effect against the development of cardiovascular disease. Dipeptidyl peptidase-4 (DPP4) inhibitors are a new class of oral hypoglycemic agents for the treatment of type 2 diabetes mellitus. Whether sitagliptin, a DPP-4 inhibitor, has a beneficial effect on vascular calcification remains undetermined.
Methods: In the present study, we fed low-density lipoprotein receptor knockout (LDLR-/-) mice a high fat diet to induce diabetic mellitus and studied the effect of orally administered sitagliptin on the high fat diet fed LDLR-/- mice aorta medial calcification, RAGE expression, oxidative stress, aorta calcium content. Tumor necrosis factor (TNF)-α combined with S100A12 was used to induce HASMC oxidative stress, activation of NADPH, up-regulation of the bone markers and RAGE expression, and cell calcium deposition. Effect of sitagliptin, siRNA for RAGE and apocynin on blunting TNF-α and S100A12 induced HASMC oxidative stress, calcification and NADPH activation were also investigated.
Results: Sitagliptin attenuated the HFD-induced LDLR-/- mice hyperlipidemia, hyperglycemia, increase in serum TNF-α, aorta calcium deposition and the expression of RAGE in the medial layer of the aorta. TNF-α combined with S100A12 stimulated HASMC RAGE expression, calcium deposition, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) activation, and up-regulation of bone marker (bone morphogenetic protein-2, Msh homeobox 2, and runt‑related transcription factor 2) expression. Sitagliptin and apocynin (APO), an NADPH oxidase inhibitor, suppressed the TNF-α+S100A12 treatment effects on the activation of NADPH oxidase and Nuclear factor (NF)-κB and the resultant oxidative stress, up-regulation of RAGE and bone markers expression and calcium deposition. Our findings suggest that sitagliptin imparts its protective effect by suppressing NADPH oxidase and NF-κB activation to blunt the up-regulation of RAGE expression.
Conclusion: Our findings suggest that sitagliptin may suppress the initiation and progression of artery calcification by inhibiting the activation of NADPH oxidase and NF-κB and the resultant up-regulation of expression of RAGE.

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This is a list of supplementary files associated with this preprint. Click to download.
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Posted 11 May, 2021
Posted 11 May, 2021
Background: Plasma advanced glycation end products (AGEs) activates the receptor for advanced glycation end products (RAGE) and the activation of RAGE is implicated to be the pathogenesis of type 2 diabetic mellitus patient vascular complications. Attenuating the activation of RAGE may exert a protective effect against the development of cardiovascular disease. Dipeptidyl peptidase-4 (DPP4) inhibitors are a new class of oral hypoglycemic agents for the treatment of type 2 diabetes mellitus. Whether sitagliptin, a DPP-4 inhibitor, has a beneficial effect on vascular calcification remains undetermined.
Methods: In the present study, we fed low-density lipoprotein receptor knockout (LDLR-/-) mice a high fat diet to induce diabetic mellitus and studied the effect of orally administered sitagliptin on the high fat diet fed LDLR-/- mice aorta medial calcification, RAGE expression, oxidative stress, aorta calcium content. Tumor necrosis factor (TNF)-α combined with S100A12 was used to induce HASMC oxidative stress, activation of NADPH, up-regulation of the bone markers and RAGE expression, and cell calcium deposition. Effect of sitagliptin, siRNA for RAGE and apocynin on blunting TNF-α and S100A12 induced HASMC oxidative stress, calcification and NADPH activation were also investigated.
Results: Sitagliptin attenuated the HFD-induced LDLR-/- mice hyperlipidemia, hyperglycemia, increase in serum TNF-α, aorta calcium deposition and the expression of RAGE in the medial layer of the aorta. TNF-α combined with S100A12 stimulated HASMC RAGE expression, calcium deposition, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) activation, and up-regulation of bone marker (bone morphogenetic protein-2, Msh homeobox 2, and runt‑related transcription factor 2) expression. Sitagliptin and apocynin (APO), an NADPH oxidase inhibitor, suppressed the TNF-α+S100A12 treatment effects on the activation of NADPH oxidase and Nuclear factor (NF)-κB and the resultant oxidative stress, up-regulation of RAGE and bone markers expression and calcium deposition. Our findings suggest that sitagliptin imparts its protective effect by suppressing NADPH oxidase and NF-κB activation to blunt the up-regulation of RAGE expression.
Conclusion: Our findings suggest that sitagliptin may suppress the initiation and progression of artery calcification by inhibiting the activation of NADPH oxidase and NF-κB and the resultant up-regulation of expression of RAGE.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5
This is a list of supplementary files associated with this preprint. Click to download.
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