Treatment with anagliptin, a DPP-4 inhibitor, decreases FABP4 concentration in patients with type 2 diabetes mellitus at a high risk for cardiovascular disease who are receiving statin therapy

The Effects of FABP4 on Cardiovascular Disease in the Aging Population

PURPOSE OF REVIEW

Fatty acid-binding protein 4 (FABP4) plays a role in lipid metabolism and cardiovascular health. In this paper, we cover FABP4 biology, its implications in atherosclerosis from observational studies, genetic factors affecting FABP4 serum levels, and ongoing drug development to target FABP4 and offer insights into future FABP4 research.

RECENT FINDINGS

FABP4 impacts cells through JAK2/STAT2 and c-kit pathways, increasing inflammatory and adhesion-related proteins. In addition, FABP4 induces angiogenesis and vascular smooth muscle cell proliferation and migration. FABP4 is established as a reliable predictive biomarker for cardiovascular disease in specific at-risk groups. Genetic studies robustly link PPARG and FABP4 variants to FABP4 serum levels. Considering the potential effects on atherosclerotic lesion development, drug discovery programs have been initiated in search for potent inhibitors of FABP4. Elevated FABP4 levels indicate an increased cardiovascular risk and is causally related to acceleration of atherosclerotic disease, However, clinical trials for FABP4 inhibition are lacking, possibly due to concerns about available compounds' side effects. Further research on FABP4 genetics and its putative causal role in cardiovascular disease is needed, particularly in aging subgroups.

DPP-4 Inhibitors Suppress Tau Phosphorylation and Promote Neuron Autophagy through the AMPK/mTOR Pathway to Ameliorate Cognitive Dysfunction in Diabetic Mellitus

Dipeptidyl peptidase-4 (DPP-4) inhibitors have been considered as incretin-based agents that signal through GLP-1R. Our high-throughput RNA sequencing (RNA-seq) and bioinformatics methods indicated that GLP-1R, downregulated in diabetes mellitus (DM), was a potential target of DPP-4 inhibitors, which was further confirmed in DM rats. Thus, this study illuminated the alleviatory mechanism of DPP-4 on cognitive dysfunction in diabetes mellitus (DM), which may be associated with GLP-1R signaling. DM rats were administered with DPP-4 inhibitors, Chloroquine (an autophagy inhibitor), Exendin 9-39 (a GLP-1R antagonist), or Compound C (a specific inhibitor of AMPK). An in vitro model of DM was induced in rat hippocampal neuronal cell line H19-7 by exposure to high glucose (HG) and high fat (HF), followed by treatment with the above inhibitors and antagonists. It was found that cognitive dysfunction was promoted, and LC3 expression was lowered in DM rats by an autophagy inhibitor. The DPP-4 inhibitors decreased cognitive dysfunction, repressed Tau phosphorylation, and enhanced GLP-1R protein level, LC3 expression, and AMPK and mTOR phosphorylation in DM rats, while GLP-1R antagonist, an autophagy inhibitor, or AMPK inhibitor counteracted these effects. Such effects were also observed in HG/HF-induced neurons. In conclusion, our data elucidated the alleviatory mechanism of DPP-4 inhibitors in the cognitive dysfunction of DM rats via the AMPK/mTOR pathway.

Adipocyte "Fatty Acid Binding Protein" Gene Polymorphisms (rs1054135, rs16909196 and rs16909187) in Jordanians with Obesity and Type 2 Diabetes Mellitus

Background

Obesity, type 2 diabetes mellitus (T2DM), and dyslipidemia may result from the interactions of genetic and environmental factors. There are controversial reports concerning the association of polymorphisms (rs1054135, rs16909196 and rs16909187) in the gene of adipocyte fatty acid binding protein (FABP4) with obesity and T2DM. Therefore, we designed this study to determine the association of these polymorphisms with obesity, T2DM, and dyslipidemia among Jordanian subjects.

Methods

The study was approved by the National Center for Diabetes, Endocrinology, and Genetics (NCDEG) Institutional Review Board (IRB). A total of 397 subjects were enrolled in the study and divided into four groups as described in materials and methods section. The fatty acid binding protein 4 (FABP4) gene containing (rs1054135, rs16909196 and rs16909187) single nucleotide polymorphisms (SNP) was amplified by polymerase chain reaction (PCR) followed by Sanger DNA sequencing of the PCR product.

Results

None of the three SNPs were associated with T2DM (p > 0.05). The rs16909187 and rs16909196 were significantly associated with obesity. The wild type (CC) of rs16909187 was significantly higher among the overweight and obese group compared with normal weight controls (OD = 2.17, 95% CI = 1.18 - 3.96, p =0.01). The wild type of rs16909196 (AA) was significantly higher among the overweight and obese group compared to controls, (OD = 2.26, 95% CI = 1.24 - 4.14, p = 0.01). These results may indicate that the wild-type may be a risk factor for obesity.Only the rs1054135 SNP was significantly associated with increased low density lipoprotein (LDL) levels in the overweight and obese group compared with the controls (p = 0.03).

Conclusions

The wild-type genotypes of rs16909196 and rs16909187 may be risk factors for obesity but not T2DM. None of the three SNPs was associated with T2DM.

Adipose extracellular matrix deposition is an indicator of obesity and metabolic disorders

Obesity and metabolic disorders are threats to human health. Extracellular matrix (ECM) is an important member of adipose microenvironment. ECM remodeling contributes to obesity and insulin resistance, but the roles of every single ECM component is still not fully understood. We observed glucose and lipids metabolic disorders in high-fat diet (HFD)-fed mice and humans with obesity. Higher levels of inflammatory factors and hormones existed in serum of HFD-fed mice. Multiple collagens, laminins, fibronectin, nidogen, and Hspg2 were upregulated in obese white adipose tissue (WAT) from mice and humans. These effects were stronger in subcutaneous WAT than visceral WAT in mice, but the fat depot difference was reversed in humans. The ECM structure and the morphology of adipocytes seeded on ECM were changed in the HFD group. In human visceral WAT, ECM genes showed positive correlations with blood lipids and glucose. In vitro, collagen I/IV and LAMA4 proteins showed similar changes with C/EBPα during the differentiation of adipocytes. Macromolecular crowders (MMC) promoted partial collagen and non-collagen gene expression. Oleic acid (OA) and MMC upregulated collagen I/IV and LAMA4 proteins, and the effects of MMC were stronger than that of OA. Moreover, MMC promoted the differentiation of adipocytes, but OA increased the size of lipid droplets. Positive correlations were observed between ECM genes and adipogenesis-related genes in adipocytes. In conclusion, some obesogens (such as HFD) induce ECM remodeling, and the upregulation of ECM components is closely related to adipogenesis, suggesting that adipose ECM deposition is an indicator of obesity and metabolic disorders.

FABP4 secreted by M1-polarized macrophages promotes synovitis and angiogenesis to exacerbate rheumatoid arthritis

Increasing evidence shows that adipokines play a vital role in the development of rheumatoid arthritis (RA). Fatty acid-binding protein 4 (FABP4), a novel adipokine that regulates inflammation and angiogenesis, has been extensively studied in a variety of organs and diseases. However, the effect of FABP4 on RA remains unclear. Here, we found that FABP4 expression was upregulated in synovial M1-polarized macrophages in RA. The increase in FABP4 promoted synovitis, angiogenesis, and cartilage degradation to exacerbate RA progression in vivo and in vitro, whereas BMS309403 (a FABP4 inhibitor) and anagliptin (dipeptidyl peptidase 4 inhibitor) inhibited FABP4 expression in serum and synovial M1-polarized macrophages in mice to alleviate RA progression. Further studies showed that constitutive activation of mammalian target of rapamycin complex 1 (mTORC1) by TSC1 deletion specifically in the myeloid lineage regulated FABP4 expression in macrophages to exacerbate RA progression in mice. In contrast, inhibition of mTORC1 by ras homolog enriched in brain (Rheb1) disruption specifically in the myeloid lineage reduced FABP4 expression in macrophages to attenuate RA development in mice. Our findings established an essential role of FABP4 that is secreted by M1-polarized macrophages in synovitis, angiogenesis, and cartilage degradation in RA. BMS309403 and anagliptin inhibited FABP4 expression in synovial M1-polarized macrophages to alleviate RA development. Hence, FABP4 may represent a potential target for RA therapy.

Anagliptin prevents lipopolysaccharide (LPS)- induced inflammation and activation of macrophages

Sepsis is a multiple organ dysfunction syndrome (MODS) induced by infection, which significantly threatens public health. The overactivation of inflammatory reactions and oxidative stress participate in the pathogenesis of sepsis. Anagliptin, a novel anti-diabetic agent widely applied for the treatment of type II diabetes, has been recently claimed to possess anti-inflammatory properties. Here, the protective effects of anagliptin on lipopolysaccharide (LPS)- stimulated macrophages will be checked to explore the possible pharmacological property of anagliptin on sepsis. The state of oxidative stress was dramatically activated by LPS, accompanied by the upregulation of toll-like receptor 4 (TLR4) and high mobility group box-1 (HMGB-1), as well as the elevated expression of inducible nitric oxide synthase (iNOS) and production of nitric oxide (NO). After treatment with anagliptin, the state of oxidative stress in macrophages was alleviated, with the downregulation of TLR4, HMGB-1, iNOS, and the declined release of NO. The excessive secretion of inflammatory factors, activation of the NF-κB pathway, and promoted expression level of receptor-interacting protein 1 (RIP1) were observed in LPS- stimulated macrophages, all of which were greatly reversed by the introduction of anagliptin. Lastly, the protective properties of anagliptin on LPS- treated macrophages, including the inhibitory effects on inflammation and the NF-κB pathway, were dramatically abolished by the overexpression of RIP1 in macrophages. Collectively, anagliptin prevented LPS-induced inflammation and activation of P338D1 macrophages by repressing the expression level of RIP1.

Differential Effects of DPP-4 Inhibitors, Anagliptin and Sitagliptin, on PCSK9 Levels in Patients with Type 2 Diabetes Mellitus who are Receiving Statin Therapy

Aim: Proprotein convertase subtilisin/kexin type 9 (PCSK9) degrades the low-density lipoprotein (LDL) receptor, leading to hypercholesterolemia and cardiovascular risk. Treatment with a statin leads to a compensatory increase in circulating PCSK9 level. Anagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to decrease LDL cholesterol (LDL-C) levels to a greater extent than that by sitagliptin, another DPP-4 inhibitor, in the Randomized Evaluation of Anagliptin versus Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) trial. We investigated PCSK9 concentration in type 2 diabetes mellitus (T2DM) and the impact of treatment with anagliptin or sitagliptin on PCSK9 level as a sub-analysis of the REASON trial.

Methods: PCSK9 concentration was measured at baseline and after 52 weeks of treatment with anagliptin ( n =122) or sitagliptin ( n =128) in patients with T2DM who were receiving statin therapy. All of the included patients had been treated with a DPP-4 inhibitor prior to randomization.

Results: Baseline PCSK9 level was positively, but not significantly, correlated with LDL-C and was independently associated with platelet count and level of triglycerides. Concomitant with reduction of LDL-C, but not hemoglobin A1c (HbA1c), by anagliptin, PCSK9 level was significantly increased by treatment with sitagliptin (218±98 vs. 242±115 ng/mL, P =0.01), but not anagliptin (233±97 vs. 250±106 ng/mL, P =0.07).

Conclusions: PCSK9 level is independently associated with platelet count and level of triglycerides, but not LDL-C, in patients with T2DM. Anagliptin reduces LDL-C level independent of HbA1c control in patients with T2DM who are on statin therapy possibly by suppressing excess statin-mediated PCSK9 induction and subsequent degradation of the LDL receptor.

Role of newer antidiabetic drugs on cardiovascular prevention and heart failure

Beyond glucemic control there are other important goals when it comes to providing integral care to patients with diabetes mellitus. A bibliographic review was made in order to identify the role played by new antidiabetic drugs in cardiovascular prevention and heart failure. The use of SLGT2i and GLP1a leads to a significant decrease in cardiovascular events, with no difference between the two, except when it comes to hospitalizations for heart failure, where the superiority of the last ones (especially dapaglifozin and empaglifozin) is evident. The current evidence regarding the effect of dpp-4i is diverse, although an increased risk of hospitalizations for heart failure is observed with the use of some drugs of this class (saxagliptin).

Dipeptidyl peptidase-4 inhibitors, glucagon-like peptide 1 receptor agonists and sodium-glucose co-transporter-2 inhibitors for people with cardiovascular disease: a network meta-analysis

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of death globally. Recently, dipeptidyl peptidase-4 inhibitors (DPP4i), glucagon-like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose co-transporter-2 inhibitors (SGLT2i) were approved for treating people with type 2 diabetes mellitus. Although metformin remains the first-line pharmacotherapy for people with type 2 diabetes mellitus, a body of evidence has recently emerged indicating that DPP4i, GLP-1RA and SGLT2i may exert positive effects on patients with known CVD.

OBJECTIVES

To systematically review the available evidence on the benefits and harms of DPP4i, GLP-1RA, and SGLT2i in people with established CVD, using network meta-analysis.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and the Conference Proceedings Citation Index on 16 July 2020. We also searched clinical trials registers on 22 August 2020. We did not restrict by language or publication status.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) investigating DPP4i, GLP-1RA, or SGLT2i that included participants with established CVD. Outcome measures of interest were CVD mortality, fatal and non-fatal myocardial infarction, fatal and non-fatal stroke, all-cause mortality, hospitalisation for heart failure (HF), and safety outcomes.

DATA COLLECTION AND ANALYSIS

Three review authors independently screened the results of searches to identify eligible studies and extracted study data. We used the GRADE approach to assess the certainty of the evidence. We conducted standard pairwise meta-analyses and network meta-analyses by pooling studies that we assessed to be of substantial homogeneity; subgroup and sensitivity analyses were also pursued to explore how study characteristics and potential effect modifiers could affect the robustness of our review findings. We analysed study data using the odds ratios (ORs) and log odds ratios (LORs) with their respective 95% confidence intervals (CIs) and credible intervals (Crls), where appropriate. We also performed narrative synthesis for included studies that were of substantial heterogeneity and that did not report quantitative data in a usable format, in order to discuss their individual findings and relevance to our review scope.

MAIN RESULTS

We included 31 studies (287 records), of which we pooled data from 20 studies (129,465 participants) for our meta-analysis. The majority of the included studies were at low risk of bias, using Cochrane's tool for assessing risk of bias. Among the 20 pooled studies, six investigated DPP4i, seven studied GLP-1RA, and the remaining seven trials evaluated SGLT2i. All outcome data described below were reported at the longest follow-up duration. 1. DPP4i versus placebo Our review suggests that DPP4i do not reduce any risk of efficacy outcomes: CVD mortality (OR 1.00, 95% CI 0.91 to 1.09; high-certainty evidence), myocardial infarction (OR 0.97, 95% CI 0.88 to 1.08; high-certainty evidence), stroke (OR 1.00, 95% CI 0.87 to 1.14; high-certainty evidence), and all-cause mortality (OR 1.03, 95% CI 0.96 to 1.11; high-certainty evidence). DPP4i probably do not reduce hospitalisation for HF (OR 0.99, 95% CI 0.80 to 1.23; moderate-certainty evidence). DPP4i may not increase the likelihood of worsening renal function (OR 1.08, 95% CI 0.88 to 1.33; low-certainty evidence) and probably do not increase the risk of bone fracture (OR 1.00, 95% CI 0.83 to 1.19; moderate-certainty evidence) or hypoglycaemia (OR 1.11, 95% CI 0.95 to 1.29; moderate-certainty evidence). They are likely to increase the risk of pancreatitis (OR 1.63, 95% CI 1.12 to 2.37; moderate-certainty evidence). 2. GLP-1RA versus placebo Our findings indicate that GLP-1RA reduce the risk of CV mortality (OR 0.87, 95% CI 0.79 to 0.95; high-certainty evidence), all-cause mortality (OR 0.88, 95% CI 0.82 to 0.95; high-certainty evidence), and stroke (OR 0.87, 95% CI 0.77 to 0.98; high-certainty evidence). GLP-1RA probably do not reduce the risk of myocardial infarction (OR 0.89, 95% CI 0.78 to 1.01; moderate-certainty evidence), and hospitalisation for HF (OR 0.95, 95% CI 0.85 to 1.06; high-certainty evidence). GLP-1RA may reduce the risk of worsening renal function (OR 0.61, 95% CI 0.44 to 0.84; low-certainty evidence), but may have no impact on pancreatitis (OR 0.96, 95% CI 0.68 to 1.35; low-certainty evidence). We are uncertain about the effect of GLP-1RA on hypoglycaemia and bone fractures. 3. SGLT2i versus placebo This review shows that SGLT2i probably reduce the risk of CV mortality (OR 0.82, 95% CI 0.70 to 0.95; moderate-certainty evidence), all-cause mortality (OR 0.84, 95% CI 0.74 to 0.96; moderate-certainty evidence), and reduce the risk of HF hospitalisation (OR 0.65, 95% CI 0.59 to 0.71; high-certainty evidence); they do not reduce the risk of myocardial infarction (OR 0.97, 95% CI 0.84 to 1.12; high-certainty evidence) and probably do not reduce the risk of stroke (OR 1.12, 95% CI 0.92 to 1.36; moderate-certainty evidence). In terms of treatment safety, SGLT2i probably reduce the incidence of worsening renal function (OR 0.59, 95% CI 0.43 to 0.82; moderate-certainty evidence), and probably have no effect on hypoglycaemia (OR 0.90, 95% CI 0.75 to 1.07; moderate-certainty evidence) or bone fracture (OR 1.02, 95% CI 0.88 to 1.18; high-certainty evidence), and may have no impact on pancreatitis (OR 0.85, 95% CI 0.39 to 1.86; low-certainty evidence). 4. Network meta-analysis Because we failed to identify direct comparisons between each class of the agents, findings from our network meta-analysis provided limited novel insights. Almost all findings from our network meta-analysis agree with those from the standard meta-analysis. GLP-1RA may not reduce the risk of stroke compared with placebo (OR 0.87, 95% CrI 0.75 to 1.0; moderate-certainty evidence), which showed similar odds estimates and wider 95% Crl compared with standard pairwise meta-analysis. Indirect estimates also supported comparison across all three classes. SGLT2i was ranked the best for CVD and all-cause mortality.

AUTHORS' CONCLUSIONS

Findings from both standard and network meta-analyses of moderate- to high-certainty evidence suggest that GLP-1RA and SGLT2i are likely to reduce the risk of CVD mortality and all-cause mortality in people with established CVD; high-certainty evidence demonstrates that treatment with SGLT2i reduce the risk of hospitalisation for HF, while moderate-certainty evidence likely supports the use of GLP-1RA to reduce fatal and non-fatal stroke. Future studies conducted in the non-diabetic CVD population will reveal the mechanisms behind how these agents improve clinical outcomes irrespective of their glucose-lowering effects.

Development of FABP4/5 inhibitors with potential therapeutic effect on type 2 Diabetes Mellitus

Fatty acid-binding protein 4 (FABP4) and fatty acid-binding protein 5 (FABP5) are promising therapeutic targets for the treatment of various metabolic diseases. However, the weak potency, low selectivity over FABP3, or poor pharmacokinetic profiles of currently reported dual FABP4/5 inhibitors impeded further research. Here, we described the characterization of a series of dual FABP4/5 inhibitors with improved metabolic stabilities and physicochemical properties based on our previous studies. Among the compounds, D9 and E1 exhibited good inhibitory activities against FABP4/5 and favorable selectivity over FABP3 in vitro. In cell-based assays, D9 and E1 exerted a decrease of FABP4 secretion, a strong anti-lipolytic effect in mature adipocytes, and suppression of MCP-1 expression in THP-1 macrophages. Moreover, D9 and E1 possessed good metabolic stabilities in mouse hepatic microsomes and acceptable pharmacokinetics profiles in ICR mice. Further in vivo experiments showed that D9 and E1 could potently decrease serum FABP4 levels and ameliorate glucose metabolism disorders in obese diabetic db/db mice. These results demonstrated that D9 and E1 could serve as lead compounds for the development of novel anti-diabetic drugs.

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.

Serum fatty acid-binding protein 4 levels and responses of pancreatic islet β-cells and α-cells in patients with type 2 diabetes

BACKGROUND

Serum fatty acid-binding protein 4 (FABP4), as an intracellular lipid chaperone and adipokine, was reported to be related to the incidence of type 2 diabetes (T2D) and diabetic complications, but its association with pancreatic islet β-cell and α-cell functions has not been fully elucidated. So the present study was to investigate the serum FABP4 levels and responses of islet β-cells and α-cells in patients with T2D.

METHODS

115 patients with T2D and 89 healthy controls (HC), who received serum FABP4 levels test, were recruited to participate in this study. Moreover, 75-g oral glucose tolerance test (OGTT) was performed in T2D patients to evaluate islet β-cell and α-cell functions. Systemic insulin sensitivity and overall insulin secretion of islet β-cell function were assessed by Matsuda index using C peptide (ISI_M-cp) and ratio of the area under the C peptide curve to the glucose curve (AUC_cp/glu) during OGTT, respectively. Fasting glucagon (Gluca_0min) and postchallenge glucagon assessed by the area under the glucagon curve (AUC_gluca) were determined during OGTT to evaluate islet α-cell function. And other various clinical variables were also measured in all participants. Skewed variables were natural log-transformed (ln), such as lnFABP4.

RESULTS

The serum FABP4 levels in T2D patients were significantly higher than those in HC (p < 0.05). And after partially adjusting for fasting plasma glucose, serum lnFABP4 levels were negatively correlated with lnISI_M-cp (r =  - 0.332, p < 0.001) and positively correlated with lnAUC_cp/glu (r = 0.324, p < 0.001), lnGluca_0min (r = 0.200, p = 0.040) and lnAUC_gluca (r = 0.311, p < 0.001), respectively, in patients with T2D. Furthermore, when multiple linear regression analyses were applied to adjust for other various clinical variables, serum lnFABP4 levels were found to remain associated with lnISI_M-cp (β =  - 0.296, t =  - 2.900, p = 0.005), lnAUC_cp/glu (β = 0.223, t = 2.038, p = 0.046), lnGluca_0min (β = 0.272, t = 2.330, p = 0.024) and lnAUC_gluca (β = 0.341, t = 3.065, p = 0.004), respectively.

CONCLUSION

Increased serum FABP4 levels were closely associated with blunted insulin sensitivity, increased insulin secretion, and elevated fasting and postchallenge glucagon levels in patients with T2D.

Effect of Add-On Therapy of Sodium-Glucose Cotransporter 2 Inhibitors and Dipeptidyl Peptidase 4 Inhibitors on Adipokines in Type 2 Diabetes Mellitus

Background

Excess adiposity is associated with an increased risk of cardiovascular disease due to metabolic changes in the body. Visceral obesity increases the risk of diabetes mellitus through adipocytokines and hence the effective targeting therapies are essential to control obesity in high-risk individuals. The study's main objective was to evaluate the effect of add-on therapy of sodium-glucose cotransporter 2 (SGLT2) inhibitors and dipeptidyl peptidase 4 (DPP4) inhibitors on visceral fat-associated serum adipokines.

Methods

The study included 90 subjects diagnosed with type 2 diabetes mellitus. The blood samples were taken before starting first-line therapy with metformin, 12 weeks after starting metformin therapy and 12 weeks after starting add-on therapy. Serum adipokines were analyzed with enzyme-linked immunosorbent assay (ELISA). Hemoglobin A1c (HbA1c) level was estimated with high-performance liquid chromatography (HPLC). The biochemical variables were measured using Cobas^® 6000 analyzer.

Results

The mean adiponectin level was significantly elevated with add-on therapy using SGLT2 inhibitors and DPP4 inhibitors (P < 0.001). The mean retinol binding protein 4 (RBP4), fatty acid binding protein 4 (FABP4) and visfatin levels were reduced considerably (P < 0.001). The SGLT2 inhibitors are more effective on serum FABP4 in patients with type 2 diabetes (P = 0.038). The mean fasting plasma glucose (FPG), postprandial blood glucose (PPBG) and HbA1c levels were reduced significantly with add-on therapy (P < 0.001). Lipid profile was also altered significantly with this add-on therapy (P < 0.001).

Conclusions

The results indicate that add-on therapy exerts a beneficial effect in type 2 diabetic patients insufficiently controlled with metformin only by altering the visceral fat-associated adipokine levels and controlling the metabolic activities.

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.

Elevated circulating FABP4 concentration predicts cardiovascular death in a general population: a 12-year prospective study

Fatty acid-binding protein 4 (FABP4) is secreted from adipose tissue and acts as an adipokine, and an elevated circulating FABP4 level is associated with metabolic disorders and atherosclerosis. However, little is known about the causal link between circulating FABP4 level and mortality in a general population. We investigated the relationship between FABP4 concentration and mortality including cardiovascular death during a 12-year period in subjects of the Tanno-Sobetsu Study, a population-based cohort (n = 721, male/female: 302/419). FABP4 concentration at baseline was significantly higher in female subjects than in male subjects. All-cause death occurred in 123 (male/female: 74/49) subjects, and 34 (male/female: 20/14) and 42 (male/female: 26/16) subjects died of cardiovascular events and cancer, respectively. When divided into 3 groups according to tertiles of FABP4 level at baseline by sex (T1–T3), Kaplan–Meier survival curves showed that there were significant differences in rates of all-cause death and cardiovascular death, but not cancer death, among the groups. Multivariable Cox proportional hazard model analysis with a restricted cubic spline showed that hazard ratio (HR) for cardiovascular death, but not that for all-cause death, significantly increased with a higher FABP4 level at baseline after adjustment of age and sex. The risk of cardiovascular death after adjustment of age, sex, body mass index and levels of brain natriuretic peptide and high-sensitivity C-reactive protein in the 3rd tertile (T3) group (HR: 4.96, 95% confidence interval: 1.20–22.3) was significantly higher than that in the 1st tertile (T1) group as the reference. In conclusion, elevated circulating FABP4 concentration predicts cardiovascular death in a general population.

Independent and Distinct Associations of FABP4 and FABP5 With Metabolic Parameters in Type 2 Diabetes Mellitus

Objective: Among fatty acid-binding proteins (FABPs), secreted forms of FABP4 and FABP5, which are expressed in adipocytes and macrophages, act as bioactive molecules. We investigated concentrations of FABP4 and FABP5 in patients with type 2 diabetes mellitus. Methods: As a sub-analysis study of the Randomized Evaluation of Anagliptin vs. Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) trial, 256 patients (male/female: 146/110, age: 68 ± 10 years) with type 2 diabetes mellitus and dyslipidemia who were receiving statin therapy were recruited. Patients who had been treated with a thiazolidinedione were excluded. Results: Several drugs which may modulate FABP4 levels including statins, dipeptidyl peptidase-4 inhibitors and angiotensin II receptor blockers had been administered in 100, 81, and 51% of the recruited patients, respectively. The level of FABP4, but not that of FABP5, was significantly higher in females than in males. Multivariable linear regression analysis demonstrated that waist circumference (β = 0.21), estimated glomerular filtration rate (β = -0.31), triglycerides (β = 0.16), and FABP5 (β = 0.39) were independent predictors of FABP4 level after adjusting age and sex. On the other hand, FABP5 level was independently associated with levels of FABP4 (β = 0.57) and high-density lipoprotein (HDL) cholesterol (β = -0.12). Conclusions: Concentrations of FABP4 and FABP5 are independent predictors of each other in patients with type 2 diabetes mellitus. There are distinct independent associations of FABP4 with renal dysfunction, adiposity and hypertriglyceridemia and there is a distinct independent association of FABP5 with a low HDL cholesterol level in type 2 diabetic patients with dyslipidemia at high risks for cardiovascular disease who are receiving statin therapy.