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Atherosclerosis is a chronic inflammatory disorder of the arterial wall leading to coronary artery disease, stroke, and peripheral arterial disease. Along with the discovery of dipeptidyl peptidase 4 (DPP4) as a therapeutic target...
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Atherosclerosis is a chronic inflammatory disorder of the arterial wall leading to coronary artery disease, stroke, and peripheral arterial disease. Along with the discovery of dipeptidyl peptidase 4 (DPP4) as a therapeutic target in type 2 diabetes, a role for DPP4 in atherosclerosis is emerging. However, until now the expression and role of other DPPs such as DPP8 and DPP9 in atherosclerosis is completely unknown. In the present study, we first investigated DPP expression in human atherosclerotic plaques. DPP4 could only be observed in endothelial cells of plaque neovessels in half of the specimens. In contrast, DPP8 and DPP9 were abundantly present in macrophage-rich regions of plaques. We then focused on DPP expression and function in macrophage differentiation, activation and apoptosis. DPP8/9 was responsible for most of the DPP activity in macrophages. During monocyte to macrophage differentiation, DPP9 was upregulated both in pro-inflammatory M1 (3.7 ± 0.3-fold increase) and anti-inflammatory M2 macrophages (3.7 ± 0.4-fold increase) whereas DPP8 expression remained unchanged. Inhibition of DPP8/9 activity with compound 1G244 reduced activation of M1 macrophages (IL-6 88 ± 16 vs. 146 ± 19 pg/ml; TNFα 3.8 ± 1.0 vs. 6.6 ± 1.9 ng/ml in treated vs. untreated cells), but not of M2 macrophages. Likewise, DPP9 silencing reduced TNFα and IL-6 secretion, pointing to a DPP9-mediated effect of the inhibitor. DPP8/9 inhibition also enhanced macrophage apoptosis (15 ± 4 vs. 7 ± 3 % in untreated cells). Because pro-inflammatory macrophages play a key role in atherogenesis, plaque rupture and subsequent infarction, DPP9 inhibition might provide interesting therapeutic prospects in reducing atherosclerosis and/or in the prevention of plaque rupture.
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Dipeptidyl peptidase 4 (DPP4) is a conserved exopeptidase with an important function in protein regulation. The activity of DPP4, an enzyme which can either be anchored to the plasma membrane or circulate free in the extra cellula...
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Dipeptidyl peptidase 4 (DPP4) is a conserved exopeptidase with an important function in protein regulation. The activity of DPP4, an enzyme which can either be anchored to the plasma membrane or circulate free in the extra cellular compartment, affects the glucose metabolism, cellular signaling, migration and differentiation, oxidative stress and the immune system. DPP4 is also expressed on the surface of osteoblasts, osteoclasts and osteocytes, and was found to play a role in collagen metabolism. Many substrates of DPP4 have an established role in bone metabolism, among which are incretins, gastrointestinal peptides and neuropeptides. In general, their effects favor bone formation, but some effects are complex and have not been completely elucidated. DPP4 and some of its substrates are known to interact with adipokines, playing an essential role in the energy metabolism. The prolongation of the half-life of incretins through DPP4 inhibition led to the development of these inhibitors to improve glucose tolerance in diabetes. Current literature indicates that the inhibition of DPP4 activity might also result in a beneficial effect on the bone metabolism, but the long-term effect of DPP4 inhibition on fracture outcome has not been entirely established. Diabetic as well as postmenopausal osteoporosis is associated with an increased activity of DPP4, as well as a shift in the expression levels of DPP4 substrates, their receptors, and adipokines. The interactions between these factors and their relationship in bone metabolism are therefore an interesting field of study. (C) 2016 Elsevier Inc. All rights reserved.
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Dipeptidyl peptidases (DPPs) are proteolytic enzymes that regulate many physiological systems by degrading signaling peptides. DPP8 and DPP9 are distinct from DPP4 in sequence, cellular localization and expression levels, thus imp...
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Dipeptidyl peptidases (DPPs) are proteolytic enzymes that regulate many physiological systems by degrading signaling peptides. DPP8 and DPP9 are distinct from DPP4 in sequence, cellular localization and expression levels, thus implying distinct functions. However, DPP8 and DPP9 expression needs further delineation. We evaluated DPP4, DPP8 and DPP9 expression using three independent methods at the mRNA, protein, and functional levels to better understand the local physiological contribution of each enzyme. Sprague Dawley rats and cynomolgus monkeys were selected for DPP4, DPP8 and DPP9 expression profiling to represent animal species commonly utilized for drug preclinical safety evaluation. A novel Xhibit assay of DPP protease activity was applied in addition to newly available antibodies for immunohistochemical localization. This combined approach can facilitate a functional evaluation of protease expression, which is important for understanding physiological relevance. Few inter-species differences were observed. Tissue mRNA and protein levels generally correlated to functional DPP4 and DPP8/9 enzymatic activity. All three proteins were seen in epithelial cells, lymphoid cells and some endothelial and vascular smooth muscle cells. Combined DPP8/DPP9 enzymatic activity was uniformly intracellular across tissues at approximately 10-fold lower levels than non-renal DPP4. Consistent levels of each DPP were detected among most non-renal tissues in rats and monkeys. DPP4 was ubiquitous, principally detected on cell membranes of epithelial and endothelial cells and was greatest in the kidney. The expression patterns suggest that DPP8 and DPP9 may act similarly across tissues, and that their actions might in part overlap with DPP4.
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Dipeptidyl peptidase 4 (DPP4), also known as CD26 is a type II transmembrane protein that is released from the cell membrane in a nonclassical secretory mechanism. This exopeptidase selectively degrades varieties of substrates inc...
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Dipeptidyl peptidase 4 (DPP4), also known as CD26 is a type II transmembrane protein that is released from the cell membrane in a nonclassical secretory mechanism. This exopeptidase selectively degrades varieties of substrates including incretin hormones, growth factors, and cytokines. A significant detectable amount of DPP4 activity can be measured in plasma as well as in different tissues such as intestinal epithelium, vascular endothelium, lymphocytes, monocytes, kidney, liver, adipose, lung, thymus, spleen, prostate, etc. Enzymatically active circulatory DPP4 is shed from the plasma membrane via proteolytic cleavage, a process responsible for the enhanced plasma DPP4 levels and activity. Elevated circulatory DPP4 activity as well as levels has been found in wide spectrum of metabolic diseases including diabetes, obesity, cardiovascular diseases, and nonalcoholic fatty liver diseases. Moreover, recent preclinical studies have further expanded the repertoire for the usage of DPP4 inhibitors in the treatment of other metabolic diseases and in their consequent complications. In the present review we highlight the reason behind the elevated circulatory DPP4 levels in metabolic diseases with a focus on the tissue of origin. We also underscore the discrepancy of protein levels with enzyme activity of circulatory DPP4 in metabolic diseases. (c) 2018 IUBMB Life, 70(2):112-119, 2018
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Dipeptidyl peptidase IV (DPP4) is a peptidase whose inhibition is beneficial in Type II diabetes treatment. Several evidences suggest potential implication of DPP4 in skin disorders such as psoriasis, keloids and fibrotic skin dis...
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Dipeptidyl peptidase IV (DPP4) is a peptidase whose inhibition is beneficial in Type II diabetes treatment. Several evidences suggest potential implication of DPP4 in skin disorders such as psoriasis, keloids and fibrotic skin diseases where its inhibition could also be beneficial. DPP4 expression in human skin was described mainly in dermal fibroblasts and a subset of keratinocytes in the basal layer. Of importance in the perspective of preclinical experimentation, DPP4 distribution in skin of non-human primate species has not been documented. This report evidences unexpected differences between a set of human and cynomolgus monkey skin samples revealing a major expression of DPP4 in eccrine sweat glands of cynomolgus monkeys but not in humans. This represents a unique distinctive feature compared to the conserved expression of dipeptidyl peptidases 8 and 9 and potential relevant DPP4 substrates such as neuropeptide Y (NPY) and receptors (NPY-receptor 1 and Neurokinin receptor). Finally the observation that cathepsin D, an unrelated protease, shows the opposite expression compared to DPP4 (present in human but not in cynomolgus monkey eccrine sweat glands) could indicate that human eccrine sweat glands evolved a divergent protease repertoire compared to non-human primates. These unexpected differences in the eccrine sweat glands protease repertoire will need to be confirmed extending the analysis to a major number of donors but could imply possible biochemical divergences, reflecting the functional evolution of the glands and the control of their activity. Our findings also demonstrate that non-human primates studies aiming at understanding DPP4 function in skin biology are not readily translatable to human.
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Dipeptidyl peptidase Ⅳ (DPP Ⅳ) is a validated target for the treatment of Type 2 diabetes, with several inhibitors currently in Phase Ⅲ clinical trials. This review will mainly focus on DPP Ⅳ inhibitors that were published in ...
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Dipeptidyl peptidase Ⅳ (DPP Ⅳ) is a validated target for the treatment of Type 2 diabetes, with several inhibitors currently in Phase Ⅲ clinical trials. This review will mainly focus on DPP Ⅳ inhibitors that were published in scientific literature and patents after 2002. Medicinal chemistry aspects of several classes of inhibitors are described with respect to inhibitory potency, selectivity over DPP8, DPP9, FAPα and DPP Ⅱ, stability and ADME/Tox issues. Although the main part of this review is on potent and selective DPP Ⅳ inhibitors, selective inhibitors for the related proline-specific dipeptidyl peptidases will be described.
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The boroProline-based dipeptidyl boronic acids were among the first DPP-IV inhibitors identified, and remain the most potent known. We introduced various substitutions at the 4-position of the boroProline ring regioselectively and...
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The boroProline-based dipeptidyl boronic acids were among the first DPP-IV inhibitors identified, and remain the most potent known. We introduced various substitutions at the 4-position of the boroProline ring regioselectively and stereoselectively, and incorporated these aminoboronic acids into a series of 4-substituted boroPro-based dipeptides. Among these dipeptidyl boronic acids, Arg-(4S)-boroHyp (4q) was the most potent inhibitor of DPP-IV, DPP8 and DPP9, while (4S)-Hyp-(4R)-boroHyp (4o) exhibited the most selectivity for DPP-IV over DPP8 and DPP9.
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Dipeptidyl-peptidase 4 (DPP4) inhibitors are among the newest treatments against type 2 diabetes- Since some flavonoids modulate DPP4 activity, we evaluated whether grape seed-derived procyanidins (GSPEs), which are antihyperglyce...
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Dipeptidyl-peptidase 4 (DPP4) inhibitors are among the newest treatments against type 2 diabetes- Since some flavonoids modulate DPP4 activity, we evaluated whether grape seed-derived procyanidins (GSPEs), which are antihyperglycemic, modulate DPP4 activity and/or expression. In vitro inhibition assays showed that GSPEs inhibit pure DPP4. Chronic GSPE treatments in intestinal human cells (Caco-2) showed a decrease of DPP4 activity and gene expression. GSPE was also assayed in vivo. Intestinal but not plasmatic DPP4 activity and gene expression were decreased by GSPE in healthy and diet-induced obese animals. Healthy rats also showed glycemia improvement after oral glucose consumption but not after an intraperitoneal glucose challenge. In genetically obese rats, only DPP4 gene expression was down-regulated. Thus, procyanidin inhibition of intestinal DPP4 activity, either directly and/or via gene expression down-regulation, could be responsible for some of their effects in glucose homeostasis.
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Dipeptidyl-peptidase 4 (DPP4) inhibitors are among the newest treatments against type 2 diabetes- Since some flavonoids modulate DPP4 activity, we evaluated whether grape seed-derived procyanidins (GSPEs), which are antihyperglyce...
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Dipeptidyl-peptidase 4 (DPP4) inhibitors are among the newest treatments against type 2 diabetes- Since some flavonoids modulate DPP4 activity, we evaluated whether grape seed-derived procyanidins (GSPEs), which are antihyperglycemic, modulate DPP4 activity and/or expression. In vitro inhibition assays showed that GSPEs inhibit pure DPP4. Chronic GSPE treatments in intestinal human cells (Caco-2) showed a decrease of DPP4 activity and gene expression. GSPE was also assayed in vivo. Intestinal but not plasmatic DPP4 activity and gene expression were decreased by GSPE in healthy and diet-induced obese animals. Healthy rats also showed glycemia improvement after oral glucose consumption but not after an intraperitoneal glucose challenge. In genetically obese rats, only DPP4 gene expression was down-regulated. Thus, procyanidin inhibition of intestinal DPP4 activity, either directly and/or via gene expression down-regulation, could be responsible for some of their effects in glucose homeostasis.
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Dipeptidyl peptidase IV (DPP4) is a promising target for the treatment of chronic metabolic type 2 diabetes mellitus (T2D). DPP4 is a highly specific serine protease involved in the regulation and cleavage of two incretin hormones...
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Dipeptidyl peptidase IV (DPP4) is a promising target for the treatment of chronic metabolic type 2 diabetes mellitus (T2D). DPP4 is a highly specific serine protease involved in the regulation and cleavage of two incretin hormones, glucagon-like peptide (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These incretin hormones are released by the gastrointestinal tract in response to ingestion of food and stimulate insulin secretion and thereby regulate glucose homeostasis with a low risk of hypoglycemia and glucagon secretion. Currently different chemical classes of DPP4 inhibitors are in last-stage of clinical trials and few of them such as sitagliptin, vildagliptin, saxagliptin alogliptin and linagliptin have already been successfully released into market. These drugs have been approved as either monotherapy or combination therapy with other oral hypoglycemic agents such as metformin, pioglitazone, sulfonylurea, glyburide and glibenclamide for the treatment of T2D. Though several clinical trial compounds were discontinued because of severe adverse toxic effects that are associated with other prolyldipeptidases include DPP8 and DPP9. The current review provides an overview of DPP4 and its inhibitors with emphasis on the structure, expression, activity, selectivity and pharmacokinetics information. This review further dwells upon the issues relating to the rational design and development of selective DPP4 inhibitors for the treatment of T2D.
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