Inhibitors of dipeptidyl peptidase 4 (DPP4) represent a novel class of antidiabetic drugs for treatment of type 2 diabetes. Because DPP4 inhibitors afford sustained reductions in HbA1c with a low risk of hypoglycemia and little effect on body weight, DPP4 inhibitors are widely employed to manage the world-wide pandemic of type 2 diabetes. For example, the DPP4 inhibitor sitagliptin is among the top 10 prescribed drugs in the USA (>100 million prescriptions per year) and is the 2nd leading branded oral antidiabetic agent in the USA. Alarmingly, evidence is accumulating that chronic DPP4 inhibition increases heart failure risk in type 2 diabetic patients. However, due to a complete lack of a theoretical model that could explain the biochemical basis of this clinical finding and due to the absence of an adequate animal model to recapitulate the clinical results, the mechanism of the increased heart failure risk in patients taking DPP4 inhibition remains unknown. Therefore, at present we do not know how or why DPP4 inhibitors cause adverse cardiac effects, which patients are at risk or how to prevent the risks of DPP4 inhibitors while sustaining the benefits. The overarching goal of this application is to remedy this situation. In this application, we propose a comprehensive model for how DPP4 inhibitors cause cardiac (and renal) fibrosis. Previously, we discovered that full-length neuropeptide Y and peptide YY [NPY(1-36) and PYY(1-36), respectively] exert pro-growth effects (i.e., cell proliferation and extracellular matrix production) on cardiac fibroblasts (CFs), preglomerular vascular smooth muscle cells (PGVSMCs), glomerular mesangial cells (GMCs). We also found that DPP4 inhibition augments the pro-growth effects of NPY(1-36) and PYY(1-36) because DPP4 normally inactivates NPY(1-36) and PYY(1-36) by removing two N-terminal amino acids. Recently, we performed preliminary studies to determine whether DPP4 substrates other than NPY(1- 36) and PYY(1-36) could also affect proliferation of, and extracellular matrix production by, CFs, PGVSMCs and GMCs and whether DPP4 inhibition augments the effects of these peptides. Our preliminary data suggest that CXCL12(1-68) may indeed activate CFs, PGVSMCs and GMCs. Moreover, these effects of CXCL12(1- 68) appear to be augmented by DPP4 inhibition and synergize with NPY(1-36) and PYY(1-36). This makes sense because CXCL12(1-68) is an excellent substrate for DPP4 and is metabolized by DPP4 to CXCL12(3- 68). CXCL12(1-68) is a potent agonist at CXCR4 receptors, while CXCL12(3-68) is not. Herein we propose (and describe experiments to test) the model that chronic DPP4 inhibition results in cardiac, and perhaps renal, fibrosis by blocking the metabolism of NPY(1-36), PYY(1-36) and CXCL12(1-68). Moreover, we propose, and have evidence supporting, the concept that insulin degrading enzyme (IDE) inhibitors (under development for type 2 diabetes) synergize with DPP4 inhibitors to worsen organ fibrosis. We will test our hypothesis in a comprehensive set of vertically-integrated (in vitro to in vivo) experiments.

Public Health Relevance

Inhibitors of dipeptidyl peptidase 4 (DPP4) represent a novel class of antidiabetic drugs for treatment of type 2 diabetes, and are widely employed to manage the world-wide pandemic of type 2 diabetes. Alarmingly, evidence is accumulating that chronic DPP4 inhibition increases heart failure risk in type 2 diabetic patients. However, due to a complete lack of a theoretical model that could explain the biochemical basis of this clinical finding and due to the absence of an adequate animal model to recapitulate the clinical results, the mechanism of the increased heart failure risk in patients taking DPP4 inhibition remains unknown. Therefore, at present we do not know how or why DPP4 inhibitors cause adverse cardiac effects, which patients are at risk or how to prevent the risks of DPP4 inhibitors while sustaining the benefits. The overarching goal of this application is to remedy this situation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL069846-15
Application #
9302034
Study Section
Hypertension and Microcirculation Study Section (HM)
Program Officer
OH, Youngsuk
Project Start
2003-04-01
Project End
2021-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
15
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Pharmacology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Jackson, Travis C; Kotermanski, Shawn E; Kochanek, Patrick M et al. (2018) Oxidative Stress Induces Release of 2'-AMP from Microglia. Brain Res :
Jackson, Edwin K; Mi, Eric; Ritov, Vladimir B et al. (2018) Extracellular Ubiquitin(1-76) and Ubiquitin(1-74) Regulate Cardiac Fibroblast Proliferation. Hypertension 72:909-917
Jackson, Edwin K; Gillespie, Delbert G; Mi, Zaichuan et al. (2018) Adenosine Receptors Influence Hypertension in Dahl Salt-Sensitive Rats: Dependence on Receptor Subtype, Salt Diet, and Sex. Hypertension 72:511-521
Jackson, Edwin K; Zhang, Yumeng; Cheng, Dongmei (2017) Alkaline Phosphatase Inhibitors Attenuate Renovascular Responses to Norepinephrine. Hypertension 69:484-493
Jackson, Edwin K; Zhang, Yumeng; Gillespie, Delbert D et al. (2017) SDF-1? (Stromal Cell-Derived Factor 1?) Induces Cardiac Fibroblasts, Renal Microvascular Smooth Muscle Cells, and Glomerular Mesangial Cells to Proliferate, Cause Hypertrophy, and Produce Collagen. J Am Heart Assoc 6:
Jackson, Edwin K (2017) Context-dependent effects of dipeptidyl peptidase 4 inhibitors. Curr Opin Nephrol Hypertens 26:83-90
Jackson, Edwin K; Kotermanski, Shawn E; Menshikova, Elizabeth V et al. (2017) Adenosine production by brain cells. J Neurochem 141:676-693
Schaufelberger, Sara A; Rosselli, Marinella; Barchiesi, Federica et al. (2016) 2-Methoxyestradiol, an endogenous 17?-estradiol metabolite, inhibits microglial proliferation and activation via an estrogen receptor-independent mechanism. Am J Physiol Endocrinol Metab 310:E313-22
Jackson, Edwin K; Menshikova, Elizabeth V; Mi, Zaichuan et al. (2016) Renal 2',3'-Cyclic Nucleotide 3'-Phosphodiesterase Is an Important Determinant of AKI Severity after Ischemia-Reperfusion. J Am Soc Nephrol 27:2069-81
Jackson, Edwin K; Boison, Detlev; Schwarzschild, Michael A et al. (2016) Purines: forgotten mediators in traumatic brain injury. J Neurochem 137:142-53

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