Dipeptidyl peptidase-4 inhibition prevents vascular aging in mice under chronic stress: Modulation of oxidative stress and inflammation

Dipeptidyl peptidase-4 deficiency prevents chronic stress-induced cardiac remodeling and dysfunction in mice

Exposure to chronic psychosocial stress is a risk factor for metabolic cardiovascular disorders. Dipeptidyl peptidase-4 (DPP-4) plays essential roles in human pathobiology, and we recently showed that DPP-4 levels are increased by chronic stress in murine models. We here investigated the role of DPP-4 in stress-related cardiac injury and dysfunction in mice, focusing on oxidative stress and cardiac apoptosis. Male mice were randomly assigned to non-stress and two-week immobilized-stress groups for biological and morphological studies. On day 14 post-stress, stress had increased blood pressure, heart weight, cardiac myocyte size, and interstitial fibrosis, impaired cardiac diastolic function, and increased plasma levels of DPP-4 and glucose. The stressed mice also had increased levels of monocyte chemoattractant protein-1, inteleukin-6, gp91phox, matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of MMP-1/-2, caspase-8, and Bax genes and/or proteins and lowered levels of Bcl-2, p-Akt, and endothelial nitric oxide synthase (eNOS) proteins. DPP-4 inhibition by either a genetic or pharmacological approach ameliorated the stress-induced targeted molecular and morphological changes. In vitro, DPP-4 inhibition also mitigated the alterations in the targeted caspase-8, Bcl-2, eNOS, and p-Akt proteins in H9c2 cardiomyocytes in response to H2O2. DPP-4 inhibition appeared to improve the stress-induced cardiac injury and dysfunction in mice, possibly via the improvement of oxidative stress and apoptosis, suggesting that DPP-4 could become a novel therapeutic target for chronic psychological stress-related metabolic cardiovascular disorders.

Fatty acid conjugated BimBH3 analogues with d‑amino acid substitution as PTPN1 inhibitors with enhanced activity, biostability and orally available potency for the treatment of diabetes

Protein tyrosine phosphatase non-receptor type 1 (PTPN1) is a crucial regulator of insulin and leptin signaling pathways, positioning it as a promising therapeutic target for the development of insulin sensitizers in the treatment of type 2 diabetes mellitus (T2DM). Our previous studies demonstrated that lipidated/acylated BimBH3 core peptide analogues function as potent PTPN1 inhibitors with potential for once-weekly hypoglycemic efficacy. Additionally, alanine scanning identified specific residues that could be modified without compromising inhibitory activity. In this study, we designed and synthesized 14 lipidated BimBH3 analogues incorporating d-amino acids through site-specific modifications to enhance peptide stability and activity. Among these, analogues D-1, D-9, D-10, D-11, D-12, and D-14 exhibited potent PTPN1 inhibitory activity, demonstrated significant resistance to proteolytic degradation, and showed good stability in mouse plasma. Notably, in glucose tolerance tests, subcutaneous administration of D-14 led to a significant 26.2 % reduction in blood glucose (AUC0-120 min), while oral administration achieved a 15.4 % reduction (AUC0-180 min), indicating promising oral bioavailability. Further analysis using molecular docking and kinetic studies confirmed the strong binding affinity of d-amino acid-containing BimBH3 analogues for PTPN1, supporting their potential for sustained hypoglycemic effects. Overall, our findings demonstrate that the dual modifications of d-amino acid substitution and lipid conjugation significantly enhance the inhibitory activity, bio-stability, and oral availability of BimBH3 analogues, highlighting their potential as novel, long-acting therapeutics for T2DM management.

The onset and the development of cardiometabolic aging: an insight into the underlying mechanisms

Metabolic compromise is crucial in aggravating age-associated chronic inflammation, oxidative stress, mitochondrial damage, increased LDL and triglycerides, and elevated blood pressure. Excessive adiposity, hyperglycemia, and insulin resistance due to aging are associated with elevated levels of damaging free radicals, inducing a proinflammatory state and hampering immune cell activity, leading to a malfunctioning cardiometabolic condition. The age-associated oxidative load and redox imbalance are contributing factors for cardiometabolic morbidities via vascular remodelling and endothelial damage. Recent evidence has claimed the importance of gut microbiota in maintaining regular metabolic activity, which declines with chronological aging and cardiometabolic comorbidities. Genetic mutations, polymorphic changes, and environmental factors strongly correlate with increased vulnerability to aberrant cardiometabolic changes by affecting key physiological pathways. Numerous studies have reported a robust link between biological aging and cardiometabolic dysfunction. This review outlines the scientific evidence exploring potential mechanisms behind the onset and development of cardiovascular and metabolic issues, particularly exacerbated with aging.

Dipeptidyl peptidase-4 disturbs adipocyte differentiation via the negative regulation of the glucagon-like peptide-1/adiponectin-cathepsin K axis in mice under chronic stress conditions

Exposure to chronic psychosocial stress is a risk factor for metabolic disorders. Because dipeptidyl peptidase-4 (DPP4) and cysteinyl cathepsin K (CTSK) play important roles in human pathobiology, we investigated the role(s) of DPP4 in stress-related adipocyte differentiation, with a focus on the glucagon-like peptide-1 (GLP-1)/adiponectin-CTSK axis in vivo and in vitro. Plasma and inguinal adipose tissue from non-stress wild-type (DPP4+/+), DPP4-knockout (DPP4-/-) and CTSK-knockout (CTSK-/-) mice, and stressed DPP4+/+, DPP4-/-, CTSK-/-, and DPP4+/+ mice underwent stress exposure plus GLP-1 receptor agonist exenatide loading for 2 weeks and then were analyzed for stress-related biological and/or morphological alterations. On day 14 under chronic stress, stress decreased the weights of adipose tissue and resulted in harmful changes in the plasma levels of DPP4, GLP-1, CTSK, adiponectin, and tumor necrosis factor-α proteins and the adipose tissue levels of CTSK, preadipocyte factor-1, fatty acid binding protein-4, CCAAT/enhancer binding protein-α, GLP-1 receptor, peroxisome proliferator-activated receptor-γ, perilipin2, secreted frizzled-related protein-4, Wnt5α, Wnt11 and β-catenin proteins and/or mRNAs as well as macrophage infiltration in adipose tissue; these changes were rectified by DPP4 deletion. GLP-1 receptor activation and CTSK deletion mimic the adipose benefits of DPP4 deficiency. In vitro, CTSK silencing and overexpression respectively prevented and facilitated stress serum and oxidative stress-induced adipocyte differentiation accompanied with changes in the levels of pref-1, C/EBP-α, and PPAR-γ in 3T3-L1 cells. Thus, these findings indicated that increased DPP4 plays an essential role in stress-related adipocyte differentiation, possibly through a negative regulation of GLP-1/adiponectin-CTSK axis activation in mice under chronic stress conditions.

Cathepsin K deficiency prevented stress-related thrombosis in a mouse FeCl3 model

BACKGROUND

Exposure to chronic psychological stress (CPS) is a risk factor for thrombotic cardiocerebrovascular diseases (CCVDs). The expression and activity of the cysteine cathepsin K (CTSK) are upregulated in stressed cardiovascular tissues, and we investigated whether CTSK is involved in chronic stress-related thrombosis, focusing on stress serum-induced endothelial apoptosis.

METHODS AND RESULTS

Eight-week-old wild-type male mice (CTSK+/+) randomly divided to non-stress and 3-week restraint stress groups received a left carotid artery iron chloride3 (FeCl3)-induced thrombosis injury for biological and morphological evaluations at specific timepoints. On day 21 post-stress/injury, the stress had enhanced the arterial thrombi weights and lengths, in addition to harmful alterations of plasma ADAMTS13, von Willebrand factor, and plasminogen activation inhibitor-1, plus injured-artery endothelial loss and CTSK protein/mRNA expression. The stressed CTSK+/+ mice had increased levels of injured arterial cleaved Notch1, Hes1, cleaved caspase8, matrix metalloproteinase-9/-2, angiotensin type 1 receptor, galactin3, p16IN4A, p22phox, gp91phox, intracellular adhesion molecule-1, TNF-α, MCP-1, and TLR-4 proteins and/or genes. Pharmacological and genetic inhibitions of CTSK ameliorated the stress-induced thrombus formation and the observed molecular and morphological changes. In cultured HUVECs, CTSK overexpression and silencing respectively increased and mitigated stressed-serum- and H2O2-induced apoptosis associated with apoptosis-related protein changes. Recombinant human CTSK degraded γ-secretase substrate in a dose-dependent manor and activated Notch1 and Hes1 expression upregulation.

CONCLUSIONS

CTSK appeared to contribute to stress-related thrombosis in mice subjected to FeCl3 stress, possibly via the modulation of vascular inflammation, oxidative production and apoptosis, suggesting that CTSK could be an effective therapeutic target for CPS-related thrombotic events in patients with CCVDs.

Association of Dipeptidylpeptidase 4 (CD26) With Chondrocyte Senescence and Radiographic Progression in Knee Osteoarthritis

OBJECTIVE

To evaluate the association of dipeptidylpeptidase 4 (DPP-4; also known as CD26) with cellular senescence of human cartilage and progression of knee osteoarthritis (OA).

METHODS

Articular cartilage sections and chondrocytes were acquired from 35 individuals undergoing total knee replacement for OA to evaluate the following: 1) the association between OA severity and established senescence markers (senescence-associated β-galactosidase activity and p16), which was quantified using immunohistochemistry and flow cytometry (n = 19 samples); 2) the coexpression of DPP-4 with established senescence markers, which was assessed using flow cytometry; and 3) expression levels of anabolic and catabolic genes, senescence-related genes, and senescence-associated secretory phenotypes in DPP-4+ and DPP-4- cells, which were isolated using fluorescence-activated cell sorting or magnetic-activated cell sorting (n = 16 samples). The concentration of soluble DPP-4 was measured in samples of synovial fluid and samples of plasma from the Prediction of Osteoarthritis Progression cohort and then evaluated for association with the severity of radiographic knee OA at baseline (n = 65 samples) and the progression of structural radiographic OA (n = 57 samples) over a 3-year period.

RESULTS

DPP-4 expression was associated with higher senescence-associated β-galactosidase activity, p16 expression, senescence-related gene and catabolic gene (ADAMTS5, MMP13, IL6, and IL8) expression, higher senescence-associated secretory phenotype secretion, and lower anabolic gene (COL2A1 and ACAN) expression in primary chondrocytes. Synovial fluid DPP-4 concentration was associated with radiographic OA progression (odds ratio 105.32; P = 0.015), proteases (synovial fluid matrix metalloproteinase 1 and matrix metalloproteinase 3), aggrecan degradation (synovial fluid sulfated glycosaminoglycan), indicators of activated macrophages (synovial fluid CD14 and CD163), and inflammation (synovial fluid interleukin-6).

CONCLUSION

Our study identifies DPP-4 as a key surface marker in senescent chondrocytes and a predictor of radiographic OA progression.

Deleterious effects of cardiomyocyte-specific prostaglandin E2 EP3 receptor overexpression on cardiac function after myocardial infarction

AIMS

Prostaglandin E2 (PGE2) is a lipid hormone that signals through 4 different G-protein coupled receptor subtypes which act to regulate key physiological processes. Our laboratory has previously reported that PGE2 through its EP3 receptor reduces cardiac contractility at the level of isolated cardiomyocytes and in the isolated working heart preparation. We therefore hypothesized that cardiomyocyte specific overexpression of the PGE2 EP3 receptor further decreases cardiac function in a mouse model of heart failure produced by myocardial infarction.

MAIN METHODS

Our study tested this hypothesis using EP3 transgenic mice (EP3 TG), which overexpress the porcine analogue of human EP3 in the cardiomyocytes, and their wildtype (WT) littermates. Mice were analyzed 2 wks after myocardial infarction (MI) or sham operation by echocardiography, RT-PCR, immunohistochemistry, and histology.

KEY FINDINGS

We found that the EP3 TG sham controls had a reduced ejection fraction, reduced fractional shortening, and an increased left ventricular dimension at systole and diastole compared to the WT sham controls. Moreover, there was a further reduction in the EP3 TG mice after myocardial infarction. Additionally, single-cell analysis of cardiomyocytes isolated from EP3 TG mice showed reduced contractility under basal conditions. Overexpression of EP3 significantly increased cardiac hypertrophy, interstitial collagen fraction, macrophage, and T-cell infiltration in the sham operated group. Interestingly, after MI, there were no changes in hypertrophy but there were changes in collagen fraction, and inflammatory cell infiltration.

SIGNIFICANCE

Overexpression of EP3 reduces cardiac function under basal conditions and this is exacerbated after myocardial infarction.

Protective effects of Dendrobium huoshanense polysaccharide on D-gal induced PC12 cells and aging mice, in vitro and in vivo studies

Dendrobium huoshanense C. Z. Tang et S. J. Cheng polysaccharide (DHP) is the essential active ingredient of D.huoshanense and has high medicinal value. A high dose of D-galactose (D-gal) is commonly utilized in the aging model establishment. In this study, we explored whether DHP shields PC12 cells and aging mice from D-gal caused damage and the possible mechanism. In vitro experiments, D-gal induced PC12 cells were used to investigate, and then DHP was used for treatment. In vivo experiments, 72 SPF ICR male mice were randomly divided into six groups (control: normal saline; model: D-gal (400 mg/kg); VE group: VE (50 μg/ml); DHP groups: D-gal + DHP (15.6 mg/ml; 31.2 mg/ml; 62.4 mg/ml)). The results showed that DHP could enhance the viability of D-gal injured PC12 cells and prevent cell apoptosis. DHP effectively promoted the transition from phase G0/G1 to phase S and inhibited cell cycle arrest. DHP has a potential neuroprotective effect on D-gal caused cognitive and memory disorders in mice. On the one hand, DHP protects the antioxidant enzymes SOD, GSH-PX, and CAT from excessive ROS buildup. On the other hand, DHP was demonstrated to block the expression of the P53/P21 signaling pathway-related proteins P53, P21, and P16. These results imply that DHP could be a potential neuroprotective agent against aging. PRACTICAL APPLICATIONS: Cognitive and memory decline caused by aging problems has become a problem in recent years. There are many theories about aging, among which oxidative stress is considered to be one of the important pathophysiological parts of various diseases in the aging process. In this study, DHP could not only improve the damage of D-Gal to PC12 cells, but also improve the cognitive and memory impairment caused by D-Gal in mice. In conclusion, this study verified the anti-aging effect of DHP from in vitro and in vivo experiments, and its mechanism may involve the P53/P21 pathway. Therefore, this study indicated that polysaccharides from Dendrobium huoshanense, a traditional Chinese medicine of homologous medicine and food, had potential and industrial value as potential anti-aging drugs.

Physical Activity on Telomere Length as a Biomarker for Aging: A Systematic Review

Background

Overall life expectancy continues to rise, approaching 80 years of age in several developed countries. However, healthy life expectancy lags far behind, which has, in turn, contributed to increasing costs in healthcare. One way to improve health and attenuate the socio-economic impact of an aging population is to increase overall fitness through physical activity. Telomere attrition or shortening is a well-known molecular marker in aging. As such, several studies have focused on whether exercise influences health and aging through telomere biology. This systematic review examines the recent literature on the effect of physical activity on telomere length (TL) and/or telomerase activity as molecular markers of aging.

Methods

A focused search was performed in the databases PubMed and Web of Science for retrieving relevant articles over the past ten years. The search contained the following keywords: exercise, sport, physical activity, fitness, sedentary, physical inactivity, telomere, telomere length, t/s ratio, and telomerase. PRISMA guidelines for systematic reviews were observed.

Results

A total of 43 articles were identified and categorized into randomized controlled trials (RCT), observational or interventional studies. RCTs (n = 8) showed inconsistent findings of increased TL length with physical activity in, e.g. obese, post-menopausal women. In comparison with a predominantly sedentary lifestyle, observational studies (n = 27) showed significantly longer TL with exercise of moderate to vigorous intensity; however, there was no consensus on the duration and type of physical activity and training modality. Interventional studies (n = 8) also showed similar findings of significantly longer TL prior to exercise intervention; however, these studies had smaller numbers of enrolled participants (mostly of high-performance athletes), and the physical activities covered a range of exercise intensities and duration. Amongst the selected studies, aerobic training of moderate to vigorous intensity is most prevalent. For telomere biology analysis, TL was determined mainly from leukocytes using qPCR. In some cases, especially in RCT and interventional studies, different sample types such as saliva, sperm, and muscle biopsies were analyzed; different leukocyte cell types and potential genetic markers in regulating telomere biology were also investigated.

Conclusions

Taken together, physical activity with regular aerobic training of moderate to vigorous intensity appears to help preserve TL. However, the optimal intensity, duration of physical activity, as well as type of exercise still need to be further elucidated. Along with TL or telomerase activity, participants’ fitness level, the type of physical activity, and training modality should be assessed at different time points in future studies, with the plan for long-term follow-up. Reducing the amount of sedentary behavior may have a positive effect of preserving and increasing TL. Further molecular characterization of telomere biology in different cell types and tissues is required in order to draw definitive causal conclusions on how physical activity affects TL and aging.

DPP4 as a Potential Candidate in Cardiovascular Disease

The rising prevalence of cardiovascular disease has become a global health concern. The occurrence of cardiovascular disease is the result of long-term interaction of many risk factors, one of which is diabetes. As a novel anti-diabetic drug, DPP4 inhibitor has been proven to be cardiovascular safe in five recently completed cardiovascular outcome trials. Accumulating studies suggest that DPP4 inhibitor has potential benefits in a variety of cardiovascular diseases, including hypertension, calcified aortic valve disease, coronary atherosclerosis, and heart failure. On the one hand, in addition to improving blood glucose control, DPP4 inhibitor is involved in controlling cardiovascular risk factors. On the other hand, DPP4 inhibitor directly regulates the occurrence and progression of cardiovascular diseases through a variety of mechanisms. In this review, we summarize the recent advances of DPP4 in cardiovascular disease, aiming to discuss DPP4 inhibitor as a potential option for cardiovascular therapy.

Contribution of Oxidative Stress (OS) in Calcific Aortic Valve Disease (CAVD): From Pathophysiology to Therapeutic Targets

Calcific aortic valve disease (CAVD) is a major cause of cardiovascular mortality and morbidity, with increased prevalence and incidence. The underlying mechanisms behind CAVD are complex, and are mainly illustrated by inflammation, mechanical stress (which induces prolonged aortic valve endothelial dysfunction), increased oxidative stress (OS) (which trigger fibrosis), and calcification of valve leaflets. To date, besides aortic valve replacement, there are no specific pharmacological treatments for CAVD. In this review, we describe the mechanisms behind aortic valvular disease, the involvement of OS as a fundamental element in disease progression with predilection in AS, and its two most frequent etiologies (calcific aortic valve disease and bicuspid aortic valve); moreover, we highlight the potential of OS as a future therapeutic target.

CBX4 Regulates Replicative Senescence of WI-38 Fibroblasts

Cellular senescence is characterized by cell cycle arrest and senescence-associated secretory phenotypes. Cellular senescence can be caused by various stress stimuli such as DNA damage, oxidative stress, and telomere attrition and is related to several chronic diseases, including atherosclerosis, Alzheimer's disease, and osteoarthritis. Chromobox homolog 4 (CBX4) has been shown to alleviate cellular senescence in human mesenchymal stem cells and is considered a possible target for senomorphic treatment. Here, we explored whether CBX4 expression is associated with replicative senescence in WI-38 fibroblasts, a classic human senescence model system. We also examined whether and how regulation of CBX4 modifies the senescence phenotype and functions as an antisenescence target in WI-38. During the serial culture of the WI-38 primary fibroblast cell line to a senescent state, we found increased expression of senescence markers, including senescence β-galactosidase (SA-βgal) activity, protein expression of p16, p21, and DPP4, and decreased proliferation marker EdU; moreover, CBX4 protein expression declined. With knockdown of CBX4, SA-βgal activity and p16 protein expression increased, and EdU decreased. With the activation of CBX4, SA-βgal activity, p16, and DPP4 protein decreased. In addition, CBX4 knockdown increased, while CBX4 activation decreased, gene expression of both CDKN2A (encoding the p16 protein) and DPP4. Genes related to DNA damage and cell cycle pathways were regulated by CBX4. These results demonstrate that CBX4 can regulate replicative senescence in a manner consistent with a senomorphic agent.

Saxagliptin ameliorated the depressive-like behavior induced by chronic unpredictable mild stress in rats: Impact on incretins and AKT/PI3K pathway

Depression is a widespread, withering illness, resulting in a massive personal suffering and economic loss. The chronic exposure to stress may be involved in the etiology of human psychiatric disorders; such as depression. In the current study, the animals were subjected to chronic unpredictable mild stress (CUMS) for 14 days. Saxagliptin (SAXA) is a member of dipeptidyl peptidase-4 (DPP-4) inhibitors class. The current study was the first one to examine the anti-depressive effect of SAXA in an experimental model of CUMS-induced depression in rats and the possible underlying mechanisms. Animals were orally treated with SAXA (0.5, 1 and 2 mg/kg) for 14 days. SAXA treatment reversed the CUMS-induced alterations in the behavioral, biochemical as well as histopathological parameters. Moreover, it hindered the CUMS-induced increase in the oxidative stress, inflammatory, and apoptotic markers. On the other hand, it increased the monoamines levels and the neurogenic brain derived neurotrophic factor (BDNF). In addition, SAXA treatment increased the incretin hormones, glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), which are linked to the activation of protein kinase B (AKT)/phosphatidylinositol3-kinase (PI3K) pathway. In conclusion, the current study revealed that the modulation of the interplay between the key events involved in depression, including oxidative stress, inflammation, and GLP-1/PI3K/AKT signaling pathway, can explain the anti-depressant activity of SAXA.

Formononetin represses cervical tumorigenesis by interfering with the activation of PD-L1 through MYC and STAT3 downregulation

Astragalus membranaceus is a traditional Chinese medicine that regulates blood sugar levels, suppresses inflammation, protects the liver, and enhances immunity. In addition, A. membranaceus is also widely used in diet therapy and is a well-known health tonic. Formononetin is a natural product isolated from A. membranaceus that has multiple biological functions, including anti-cancer activity. However, the mechanism by which formononetin inhibits tumor growth is not fully understood. In this present study, we demonstrated that formononetin suppresses PD-L1 protein synthesis via reduction of MYC and STAT3 protein expression. Furthermore, formononetin markedly reduced the expression of MYC protein via the RAS/ERK signaling pathway and inhibited STAT3 activation through JAK1/STAT3 pathway. Co-immunoprecipitation experiments illustrated that formononetin suppresses protein expression of PD-L1 by interfering with the interaction between MYC and STAT3. Meanwhile, formononetin promoted PD-L1 protein degradation via TFEB and TFE3-mediated lysosome biogenesis. T cell killing assay revealed that formononetin could enhance the activity of cytotoxic T lymphocytes (CTLs) and restore ability to kill tumor cells in a co-culture system of T cells and tumor cells. In addition, formononetin inhibited cell proliferation, tube formation, cell migration, and promoted tumor cell apoptosis by suppressing PD-L1. Finally, the inhibitory effect of formononetin on tumor growth was confirmed in a murine xenograft model. The present study revealed the anti-tumor potential of formononetin, and the findings should support further research and development of anti-cancer drugs for cervical cancer.

Pleiotropic Benefits of DPP-4 Inhibitors Beyond Glycemic Control

Dipeptidyl peptidase (DPP)-4 inhibitors are oral anti-diabetic medications that block the activity of the ubiquitous enzyme DPP-4. Inhibition of this enzyme increases the level of circulating active glucagon-like peptide (GLP)-1 secreted from L-cells in the small intestine. GLP-1 increases the glucose level, dependent on insulin secretion from pancreatic β-cells; it also decreases the abnormally increased level of glucagon, eventually decreasing the blood glucose level in patients with type 2 diabetes. DPP-4 is involved in many physiological processes other than the degradation of GLP-1. Therefore, the inhibition of DPP-4 may have numerous effects beyond glucose control. In this article, we review the pleiotropic effects of DPP-4 inhibitors beyond glucose control, including their strong beneficial effects on the stress induced accelerated senescence of vascular cells, and the possible clinical implications of these effects.

Omarigliptin Prevents TNF-α-Induced Cellular Senescence in Rat Aorta Vascular Smooth Muscle Cells

Cellular senescence is one of the most significant factors involved in aging and age-related diseases. Senescence of vascular smooth muscle cells (VSMCs) adversely affects the function of the cardiovascular system and contributes to the development of atherosclerosis, hypertension, and other cardiovascular diseases. Glucagon-like peptide-1 (GLP-1) is an important incretin hormone involved in insulin release and vascular tone. GLP-1 is quickly degraded by the enzyme dipeptidyl peptidase-4 (DPP-4). Omarigliptin is a new DPP-4 inhibitor that has demonstrated anti-inflammatory and antioxidative stress properties. In the present study, we investigated the effects of the selective DPP-4 inhibitor omarigliptin (OMG) on VSMCs exposed to insult from tumor necrosis factor-α (TNF-α), one of the main inflammatory signaling molecules involved in cellular senescence. We found that OMG could suppress TNF-α-induced expression of pro-inflammatory cytokines (interleukin-1β (IL-1β), IL-6, and IL-8) and inhibit oxidative stress by reducing the production of H2O2 and protein carbonyl. OMG ameliorated the increase in senescence-associated β-galactosidase (SA-β-gal) and telomerase activity induced by TNF-α. The plasminogen activator inhibitor-1 (PAI-1)/p53/p21 pathway is a key inducer of cellular senescence. OMG ameliorated the acetylation of p53 at lysine 382 (K382) and subsequent activation of p21 via inhibition of PAI-1. Importantly, our experiments revealed that blockage of silent information-regulator 1 (SIRT1) abolished the inhibitory effects of OMG on p53 acetylation, SA-β-gal activity, and telomerase activity in VSMCs. These results suggest that OMG may have the potential to delay or prevent the progression of age-related cardiovascular diseases by modulating the activity of SIRT1.

The Emergence of Senescent Surface Biomarkers as Senotherapeutic Targets

Senescence is linked to a wide range of age-associated diseases and physiological declines. Thus, senotherapeutics are emerging to suppress the detrimental effects of senescence either by senomorphics or senolytics. Senomorphics suppress the traits associated with senescence phenotypes, while senolytics aim to clear senescent cells by suppressing their survival and enhancing the apoptotic pathways. The main goal of these approaches is to suppress the proinflammatory senescence-associated secretory phenotype (SASP) and to promote the immune recognition and elimination of senescent cells. One increasingly attractive approach is the targeting of molecules or proteins specifically present on the surface of senescent cells. These proteins may play roles in the maintenance and survival of senescent cells and hence can be targeted for senolysis. In this review, we summarize the recent knowledge regarding senolysis with a focus on novel surface biomarkers of cellular senescence and discuss their emergence as senotherapeutic targets.

Dipeptidyl peptidase-4 inhibition prevents lung injury in mice under chronic stress via the modulation of oxidative stress and inflammation

Exposure to chronic psychosocial stress is a risk factor for various pulmonary diseases. In view of the essential role of dipeptidyl peptidase 4 (DPP4) in animal and human lung pathobiology, we investigated the role of DPP4 in stress-related lung injury in mice. Eight-week-old male mice were randomly divided into a non-stress group and a 2-week immobilization stress group. Non-stress control mice were left undisturbed. The mice subjected to immobilized stress were randomly assigned to the vehicle or the DPP4 inhibitor anagliptin for 2 weeks. Chronic stress reduced subcutaneous and inguinal adipose volumes and increased blood DPP4 levels. The stressed mice showed increased levels in the lungs of genes and/or proteins related to oxidative stress (p67^phox, p47^phox, p22^phox and gp91^phox), inflammation (monocyte chemoattractant protein-1, vascular cell adhesion molecule-1, and intracellular adhesion molecule-1), apoptosis (caspase-3, -8, -9), senescence (p16^INK4A, p21, and p53) and proteolysis (matrix metalloproteinase-2 to -9, cathepsin S/K, and tissue inhibitor of matrix metalloproteinase-1 and -2), and reduced levels of eNOS, Sirt1, and Bcl-2 proteins; and these effects were reversed by genetic and pharmacological inhibitions of DPP4. We then exposed human umbilical vein endothelial cells in vitro to hydrogen peroxide; anagliptin treatment was also observed to mitigate oxidative and inflammatory molecules in this setting. Anagliptin can improve lung injury in stressed mice, possibly by mitigating vascular inflammation, oxidative stress production, and proteolysis. DPP4 may become a new therapeutic target for chronic psychological stress-related lung disease in humans and animals.

Endothelial Dysfunction in Atherosclerotic Cardiovascular Diseases and Beyond: From Mechanism to Pharmacotherapies

The endothelium, a cellular monolayer lining the blood vessel wall, plays a critical role in maintaining multiorgan health and homeostasis. Endothelial functions in health include dynamic maintenance of vascular tone, angiogenesis, hemostasis, and the provision of an antioxidant, anti-inflammatory, and antithrombotic interface. Dysfunction of the vascular endothelium presents with impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, and endothelial cell senescence. Recent studies have implicated altered endothelial cell metabolism and endothelial-to-mesenchymal transition as new features of endothelial dysfunction. Endothelial dysfunction is regarded as a hallmark of many diverse human panvascular diseases, including atherosclerosis, hypertension, and diabetes. Endothelial dysfunction has also been implicated in severe coronavirus disease 2019. Many clinically used pharmacotherapies, ranging from traditional lipid-lowering drugs, antihypertensive drugs, and antidiabetic drugs to proprotein convertase subtilisin/kexin type 9 inhibitors and interleukin 1β monoclonal antibodies, counter endothelial dysfunction as part of their clinical benefits. The regulation of endothelial dysfunction by noncoding RNAs has provided novel insights into these newly described regulators of endothelial dysfunction, thus yielding potential new therapeutic approaches. Altogether, a better understanding of the versatile (dys)functions of endothelial cells will not only deepen our comprehension of human diseases but also accelerate effective therapeutic drug discovery. In this review, we provide a timely overview of the multiple layers of endothelial function, describe the consequences and mechanisms of endothelial dysfunction, and identify pathways to effective targeted therapies. SIGNIFICANCE STATEMENT: The endothelium was initially considered to be a semipermeable biomechanical barrier and gatekeeper of vascular health. In recent decades, a deepened understanding of the biological functions of the endothelium has led to its recognition as a ubiquitous tissue regulating vascular tone, cell behavior, innate immunity, cell-cell interactions, and cell metabolism in the vessel wall. Endothelial dysfunction is the hallmark of cardiovascular, metabolic, and emerging infectious diseases. Pharmacotherapies targeting endothelial dysfunction have potential for treatment of cardiovascular and many other diseases.

Role of Dipeptidyl Peptidase-4 in Atherosclerotic Cardiovascular Disease in Humans and Animals with Chronic Stress

Exposure to psychosocial stress is a risk factor for cardiovascular disease, including vascular atherosclerosis-based cardiovascular disease (ACVD). Dipeptidyl peptidase-4 (DPP-4) is a complex enzyme that acts as a membrane-anchored cell surface exopeptidase. DPP-4 is upregulated in metabolic and inflammatory cardiovascular disorders. DPP-4 exhibits many physiological and pharmacological functions by regulating its extremely abundant substrates, such as glucagon-like peptide-1 (GLP-1). Over the last 10 years, emerging data have demonstrated unexpected roles of DPP-4 in extracellular and intracellular signaling, immune activation, inflammation, oxidative stress production, cell apoptosis, insulin resistance, and lipid metabolism. This mini-review focuses on recent novel findings in this field, highlighting a DPP-4-mediated regulation of GLP-1-dependent and -independent signaling pathways as a potential therapeutic molecular target in treatments of chronic psychological stress-related ACVD in humans and animals.

Effects of anagliptin on the stress induced accelerated senescence of human umbilical vein endothelial cells

Background

Dipeptidyl peptidase 4 (DPP-4) inhibitors have been used to treat type 2 diabetes mellitus (T2DM) via inhibition of the enzymatic activity of DPP-4 in degrading active circulating glucagon-like peptide-1. In addition to their glucose-lowering effect, DPP-4 inhibitors have pleiotropic effects. Cellular senescence regarded as important pathophysiological mechanism underlying many degenerative diseases, including atherosclerosis. This study was performed to examine whether the DPP-4 inhibitor, anagliptin, can directly protect against stress-induced accelerated senescence (SIAS) of vascular endothelial cells, regardless of changes in ambient glucose level.

Methods

Cultured human umbilical vein endothelial cells (HUVECs) were exposed to various concentrations of H₂O₂, and a fixed high concentration of glucose (25 mM) with varying concentrations of palmitate. Changes in cell viability, senescence-associated beta-galactosidase (SA-β-Gal), p16 protein, markers of endoplasmic reticulum (ER) stress, NOX4, NLRP inflammasome, lactate dehydrogenase (LDH) release and interleukin (IL) 1β levels were measured by Cell Counting Kit-8 assay, immunofluorescent staining, Western blotting, and enzyme-linked immunosorbent assay, respectively before and after application of anagliptin.

Results

The application of oxidative and glucolipotoxic stresses markedly increased the degree of SIAS of HUVECs, represented by increased SA-β-Gal immunopositivity and p16 protein expression. Aggravation of ER stress and inflammatory response were also observed through increased levels of ATF4, CHOP, peIF2α, NOX4, NLRP inflammasome, LDH, and IL1β. These changes were markedly reversed by the administration of anagliptin.

Conclusions

The DPP-4 inhibitor anagliptin effectively protects HUVECs against SIAS, suggesting its potential use in the development of new treatment strategies for aging.

Probable Causes of Alzheimer’s Disease

A three-part mechanism is proposed for the induction of Alzheimer’s disease: (1) decreased blood lactic acid; (2) increased blood ceramide and adipokines; (3) decreased blood folic acid. The age-related nature of these mechanisms comes from age-associated decreased muscle mass, increased visceral fat and changes in diet. This mechanism also explains why many people do not develop Alzheimer’s disease. Simple changes in lifestyle and diet can prevent Alzheimer’s disease. Alzheimer’s disease is caused by a cascade of events that culminates in damage to the blood–brain barrier and damage to neurons. The blood–brain barrier keeps toxic molecules out of the brain and retains essential molecules in the brain. Lactic acid is a nutrient to the brain and is produced by exercise. Damage to endothelial cells and pericytes by inadequate lactic acid leads to blood–brain barrier damage and brain damage. Inadequate folate intake and oxidative stress induced by activation of transient receptor potential cation channels and endothelial nitric oxide synthase damage the blood–brain barrier. NAD depletion due to inadequate intake of nicotinamide and alterations in the kynurenine pathway damages neurons. Changes in microRNA levels may be the terminal events that cause neuronal death leading to Alzheimer’s disease. A new mechanism of Alzheimer’s disease induction is presented involving lactic acid, ceramide, IL-1β, tumor necrosis factor α, folate, nicotinamide, kynurenine metabolites and microRNA.

Making Connections: p53 and the Cathepsin Proteases as Co-Regulators of Cancer and Apoptosis

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the p53 and cathepsin proteins. While it has been demonstrated that the p53 protein can directly induce the leakage of cathepsin proteases from the lysosome, directly triggering cell death, little is known about what factors set the threshold at which the lysosome can become permeabilized. It appears that the expression levels of cathepsin proteases may be central to this process, with some of them being transcriptionally regulated by p53. The consequences of such a mechanism have serious implications for lysosomal-mediated apoptosis and have significant input into the design of therapeutics and their strategic use. In this review, we highlight the importance of extending such findings to other cathepsin family members and the need to assess the roles of p53 isoforms and mutants in furthering this mechanism.

Abstract

While viewed as the “guardian of the genome”, the importance of the tumor suppressor p53 protein has increasingly gained ever more recognition in modulating additional modes of action related to cell death. Slowly but surely, its importance has evolved from a mutated genetic locus heavily implicated in a wide array of cancer types to modulating lysosomal-mediated cell death either directly or indirectly through the transcriptional regulation of the key signal transduction pathway intermediates involved in this. As an important step in determining the fate of cells in response to cytotoxicity or during stress response, lysosomal-mediated cell death has also become strongly interwoven with the key components that give the lysosome functionality in the form of the cathepsin proteases. While a number of articles have been published highlighting the independent input of p53 or cathepsins to cellular homeostasis and disease progression, one key area that warrants further focus is the regulatory relationship that p53 and its isoforms share with such proteases in regulating lysosomal-mediated cell death. Herein, we review recent developments that have shaped this relationship and highlight key areas that need further exploration to aid novel therapeutic design and intervention strategies.

Combination therapy with dipeptidyl peptidase-4 and P2X7 purinoceptor inhibitors gives rise to antiepileptic effects in rats

OBJECTIVE(S)

Although the available therapeutic agents alleviate the symptoms in patients with temporal lobe epilepsy (TLE), these antiepileptic drugs do not provide adequate control of seizures in 30-40 % of patients. This study was conducted to evaluate anti-epileptic effects of simultaneous inhibition of dipeptidyl peptidase-4 and P2 × 7 purinoceptors in Kainate treated rats.

MATERIALS AND METHODS

Brilliant Blue G)BBG(, linagliptin)lin(and lin + BBG were administrated 30 min prior to induction of the intrahippocampal kainate model of epilepsy in male Wistar rats. In the case of valproic acid group, the animals intraperitoneally received valproic acid for 7 consecutive days prior to induction of the model. We carried out histological evaluations, monitoring of behavior, recording of intracranial electroencepholography (IEEG), and determination of astrogliosis and DNA fragmentation using ELISA methods.

RESULTS

Our results showed that BBG and lin combination therapy had better effects on decrease in astrogliosis, DNA fragmentation and cognitive disturbances than ones whereas its effects on neuronal survival and seizure severity was similar to only BBG or lin. Likewise, the effects of lin + BBG on decrease in DNA fragmentation and cognitive disturbances were better than valproic acid group.

CONCLUSION

Our findings suggest that simultaneous inhibition of dipeptidyl peptidase-4 and P2 × 7 purinoceptors might more efficiently provide protection against progression of the kainate-induced TLE in rats.

lncRNA FGD5 antisense RNA 1 upregulates RORA to suppress hypoxic injury of human cardiomyocyte cells by inhibiting oxidative stress and apoptosis via miR‑195

FGD5 antisense RNA 1 (FGD5-AS1) is a long non-coding RNA in acute myocardial infarction (AMI), which is primarily caused by myocardial ischemia-hypoxia. Retinoid acid receptor-related orphan receptor α (RORA) is a key protector in maintaining heart function. However, the roles of FGD5-AS1 and RORA in AMI have not previously been elucidated. The present study investigated the effect and mechanism of FGD5-AS1 and RORA in human cardiomyocyte AC16 cells under hypoxia. Reverse transcription-quantitative PCR and western blotting demonstrated that FGD5-AS1 and RORA were downregulated in the serum of patients with AMI and hypoxia-challenged AC16 cells. Functional experiments were performed via assays, flow cytometry and western blotting. In response to hypoxia, superoxide dismutase (SOD) activity was inhibited, but apoptosis rate and levels of reactive oxygen species and malondialdehyde were promoted in AC16 cells, accompanied by increased Bax and cleaved caspase-3 expression levels, and decreased SOD2 and glutathione peroxidase 1 expression levels. However, hypoxia-induced oxidative stress and apoptosis in AC16 cells were attenuated by ectopic expression of FGD5-AS1 or RORA. Moreover, silencing RORA counteracted the suppressive role of FGD5-AS1 overexpression in hypoxic injury. FGD5-AS1 controlled RORA expression levels via microRNA-195-5p (miR-195), as confirmed by dual-luciferase reporter and RNA pull-down assays. Consistently, miR-195 knockdown suppressed hypoxia-induced oxidative stress and apoptosis in AC16 cells, which was abrogated by downregulating FGD5-AS1 or RORA. In conclusion, FGD5-AS1 modulated hypoxic injury in human cardiomyocytes partially via the miR-195/RORA axis, suggesting FGD5-AS1 as a potential target in interfering with the progression of AMI.

Adaptive immune disorders in hypertension and heart failure: focusing on T-cell subset activation and clinical implications

: Hypertension is a growing health concern worldwide. Established hypertension is a causative factor of heart failure, which is characterized by increased vascular resistance and intractable uncontrolled blood pressure. Hypertension and heart failure have multiple causes and complex pathophysiology but cellular immunity is thought to contribute to the development of both. Recent studies showed that T cells play critical roles in hypertension and heart failure in humans and animals, with various stimuli leading to the formation of effector T cells that infiltrate the cardiovascular wall. Monocytes/macrophages also accumulate in the cardiovascular wall. Various cytokines (e.g. interleukin-6, interleukin-17, interleukin-10, tumor necrosis factor-α, and interferon-γ) released from immune cells of various subtypes promote vascular senescence and elastic laminal degradation as well as cardiac fibrosis and/or hypertrophy, leading to cardiovascular structural alterations and dysfunction. Recent laboratory evidence has defined a link between inflammation and the immune system in initiation and progression of hypertension and heart failure. Moreover, cross-talk among natural killer cells, adaptive immune cells (T cells and B cells), and innate immune cells (i.e. monocytes, macrophages, neutrophils, and dendritic cells) contributes to end-cardiovasculature damage and dysfunction in hypertension and heart failure. Clinical and experimental studies on the diagnostic potential of T-cell subsets revealed that blood regulatory T cells, CD4 cells, CD8 T cells, and the ratio of CD4 to CD8 T cells show promise as biomarkers of hypertension and heart failure. Therapeutic interventions to suppress activation of these cells may prove beneficial in reducing end-organ damage and preventing consequences of cardiovascular failure, including hypertension of heart failure.

Effects of chronic immobilization stress on biokinetics and dosimetry of 67Ga in a murine model

The aim of this work is to determine the effect of chronic immobilization stress on kinetics and dosimetry of ⁶⁷Ga in a mouse model. A control group (CG) and a stress group (SG), each with 15 mice, were included in the study, and the latter group was subjected to a chronic immobilization stress model 2 h daily for 14 consecutive days. At day 13, ⁶⁷Ga-citrate was administered intraperitoneally (11.24 ± 0.44 MBq) to each mouse. Then, sets of three mice were obtained sequentially at 24, 36, 48, 60 and 72 h, in which the radionuclide activity was measured with an activity counter. The ⁶⁷Ga biokinetic data showed a fast blood clearance in the SG, with a mean residence time of 0.06 h. The calculated mean radiation absorbed doses were: liver (2.45 × 10^-03 Gy), heart (3.17 × 10^-04 Gy) and kidney (1.88 × 10^-04 Gy) in the SG. The results show that stress reduced weight gain by approximately 13% and also increased adrenal gland weight by 26%. On the other hand, chronic stress accelerates ⁶⁷Ga clearance after 24 h compared to normal conditions. It is concluded that murine organisms under chronic immobilization stress have higher gallium-67 clearance rates, decreasing the cumulated activity and absorbed dose in all organs.