Fasting serum dipeptidyl peptidase-4 activity is independently associated with alanine aminotransferase in type 1 diabetic patients

Insights into the Roles of GLP-1, DPP-4, and SGLT2 at the Crossroads of Cardiovascular, Renal, and Metabolic Pathophysiology

In recent years, new drugs for the treatment of type 2 diabetes (T2D) have been proposed, including glucagon-like peptide 1 (GLP-1) agonists or sodium-glucose cotransporter 2 (SGLT2) inhibitors and dipeptidyl peptidase-4 (DPP-4) inhibitors. Over time, some of these agents (in particular, GLP-1 agonists and SGLT2 inhibitors), which were initially developed for their glucose-lowering actions, have demonstrated significant beneficial pleiotropic effects, thus expanding their potential therapeutic applications. This review aims to discuss the mechanisms, pleiotropic effects, and therapeutic potential of GLP-1, DPP-4, and SGLT2, with a particular focus on their cardiorenal benefits beyond glycemic control.

Association of plasma dipeptidyl peptidase-4 activity with non-alcoholic fatty liver disease in nondiabetic Chinese population

OBJECTIVE

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is attributed to a "multi-hits hypothesis" involving insulin resistance, oxidative stress and inflammation. Dipeptidyl peptidase-4 (DPP4) was identified as a novel adipokine capable of enhancing the"multi-hits". Hence, we investigated the association between plasma DPP4 activity and NAFLD in nondiabetic Chinese population.

DESIGN AND METHODS

We performed a cross-sectional study using data from 1105 subjects (36-79years) in Guilin between 2015 and 2016. Plasma DPP4 activity, homeostatic model assessment of insulin resistance (HOMA-IR), oxidative stress parameters, and inflammatory markers were measured in all participants. NAFLD and its severity were diagnosed by ultrasound after the exclusion of alcohol abuse and other liver diseases.

RESULTS

Participants in the highest quartile of DPP4 activity had higher HOMA-IR, nitrotyrosine, 8-iso-PGF2a, interleukin-6, CRP, alanine aminotransferase, aspartate aminotransferase and γ-glutamyltransferase compared with those in the lowest quartile (all P<0.05). Plasma DPP4 activity gradually increased across the groups according to the ultrasonographic severity of steatosis (P<0.001 for the trend). In the highest DPP4 quartile, NAFLD risk was higher (odds ratio 1.88; 95% CI 1.04-3.37) than in the lowest quartile after adjustment for confounders. The risk for NAFLD increased more with higher levels of DPP4 activity, HOMA-IR, nitrotyrosine, 8-iso-PGF2a, interleukin-6 and CRP.

CONCLUSIONS

Plasma DPP4 activity is significantly associated with NAFLD. The underlying mechanisms may be partly attributed to the interactions between insulin resistance, oxidative stress, inflammation, and DPP4.

Prognostic value of plasma DPP4 activity in ST-elevation myocardial infarction

Background

Dipeptidyl peptidase-4 (DPP4) regulates blood glucose levels and inflammation, and it is also implicated in the pathophysiological process of myocardial infarction (MI). Plasma DPP4 activity (DPP4a) may provide prognostic information regarding outcomes for ST-segment elevation MI (STEMI) patients.

Methods

Blood samples were obtained from 625 consecutively admitted, percutaneous coronary intervention-treated STEMI patients with a mean age of 57 years old. DPP4a was quantified using enzymatic assays.

Results

The median follow-up period was 30 months. Multivariate Cox-regression analyses (adjusted for confounding variables) showed that a 1 U/L increase of DPP4a did not associate with risks of major adverse cardiac or cerebrovascular events (MACCE), cardiovascular mortality, MI, heart failure readmission, stroke, non-cardiovascular mortality and repeated revascularization. However, in a subset of 149 diabetic STEMI patients, DPP4a associated with an increased risk of MACCE (HR 1.16; 95% CI 1.04–1.30; p = 0.01).

Conclusions

DPP4a did not associate with cardiovascular events and non-cardiovascular mortality in non-diabetic STEMI patients. However, DPP4a may be associated with future MACCE in diabetic STEMI patients.

Trial registration NCT03046576, registered on 5 February, 2017, retrospectively registered

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0553-3) contains supplementary material, which is available to authorized users.

Altered circulating concentrations of active glucagon-like peptide (GLP-1) and dipeptidyl peptidase 4 (DPP4) in obese subjects and their association with insulin resistance

OBJECTIVES

Soluble DPP4 (sDPP4) is a novel adipokine that degrades glucagon-like peptide (GLP-1). We evaluated the fasting serum levels of active GLP-1 and sDPP4 in obese, overweight and normal weight subjects to assess the association between sDPP4 levels, active GLP-1 levels and insulin resistance in obese subjects.

METHODS

The study involved 235 Malaysian subjects who were randomly selected (66 normal weight subjects, 97 overweight, 59 obese subjects, and 13 subjects who were underweight). Serum sDPP4 and active GLP-1 levels were examined by enzyme-linked immunosorbent assay (ELISA). Also, body mass index kg/m² (BMI), lipid profiles, insulin and glucose levels were evaluated. Insulin resistance (IR) was estimated via the homeostasis model assessment for insulin resistance (HOMA-IR).

RESULTS

Serum sDPP4 levels were significantly higher in obese subjects compared to normal weight subjects (p=0.034), whereas serum levels of active GLP-1 were lower (p=0.021). In obese subjects, sDPP4 levels correlated negatively with active GLP-1 levels (r²=-0.326, p=0.015). Furthermore, linear regression showed that sDPP4 levels were positively associated with insulin resistance (B=82.28, p=0.023) in obese subjects.

CONCLUSION

Elevated serum sDPP4 levels and reduced GLP-1 levels were observed in obese subjects. In addition, sDPP4 levels correlated negatively with active GLP-1 levels but was positively associated with insulin resistance. This finding provides evidence that sDPP4 and GLP-1 may play an important role in the pathogenesis of obesity, suggesting that sDPP4 may be valuable as an early marker for the augmented risk of obesity and insulin resistance.