The role of dipeptidyl peptidase 4 (DPP4) in the preservation of renal function: DPP4 involvement in hemoglobin expression

Sitagliptin Induces Tolerogenic Human Dendritic Cells

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-β, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-β) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-β+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection.

Metformin as a promising target for DPP4 expression: computational modeling and experimental validation

Metformin is a regularly prescribed and low-cost generic medication. Metformin has been proposed as a target for Dipeptidyl-peptidase 4 (DPP4) expression in various clinical disorders. We provide insilco investigations on molecular docking and dynamic modeling of metformin and DPP4 potential interactions. Moreover, we conducted bioinformatic studies to highlight the clinical significance of DPP4 expression and mutation in various types of malignancies, as well as the invasion of different immune cells into the tumor microenvironment. We believe the present proposal's findings have crucial implications for understanding how metformin may confer health advantages by targeting DPP4 expression in malignancies.

Comparison of effects of Empagliflozin and Linagliptin on renal function and glycaemic control: a double-blind, randomized clinical trial

Background

This study aimed to compare the effects of Linagliptin and Empagliflozin on renal function and glycaemic control in patients with type 2 diabetes mellitus (DM).

Method

We conducted a randomized, double-blind, parallel trial on patients aged 30 to 80 years with type 2 DM and HbA1c ≤ 9%, regardless of background medical therapy, to compare the effects of Empagliflozin and Linagliptin on albuminuria, FBS, HbA1c, and eGFR. Participants were given the mentioned drugs for 12 weeks. Statistical analysis was performed using appropriate tests in IBM™SPSS® statistics software for windows version 24.

Results

In total, 60 patients participated in the study, thirty patients in each group. The mean age of participants was 56.8 (SD = 8.15) in the Empagliflozin group and 60.9 (SD = 7.22) in the Linagliptin group. Before the intervention, FBS, HbA1C, and albuminuria values were significantly higher in the Empagliflozin group than those in the Linagliptin group (P < 0.05), but there was no significant difference between groups regarding eGFR (P = 0.271). Changes in the FBS, HbA1C, and eGFR were not significantly different between groups (P > 0.05), but there was more decrease in albuminuria in the Empagliflozin group compared to the Linagliptin group (P = 0.001, Cohen’s d = 0.98).

Conclusions

Regardless of baseline albuminuria, eGFR, or HbA1c, Empagliflozin 10 mg daily significantly reduced albuminuria at 12 weeks compared to Linagliptin 5 mg daily in patients with type 2 diabetes.

Trial registration

Iranian Registry of Clinical Trials, IRCT20200722048176N1. Registered 3 August 2020.

DPP4 gene silencing inhibits proliferation and epithelial-mesenchymal transition of papillary thyroid carcinoma cells through suppression of the MAPK pathway

PURPOSE

Papillary thyroid carcinoma (PTC) is characterized by epithelial malignancy and is the most prevalent thyroid neoplasm with the best overall prognosis. Notably, recently published studies have indicated remarkably high expression of dipeptidyl peptidase 4 (DPP4) in PTC. However, the underlying molecular mechanism and regulatory factors of PTC progression remain unknown. Therefore, the current study aimed to elucidate the effects of DPP4 gene silencing on PTC and further investigated whether the mechanism of PTC progression is related to the mitogen-activated protein kinase (MAPK) pathway.

METHODS

Herein, microarray-based gene expression profiling of PTC was conducted to identify the differentially expressed genes between tumor thyroid tissue and normal thyroid tissue as well as the underlying signaling pathway involved in PTC pathogenesis. Moreover, protein quantification was performed to assess the protein expression of DPP4 in PTC tissues collected from 65 patients. In addition, DPP4 was silenced in PTC cell lines (GLAG-66 and TPC-1) through siRNA-mediated DPP4 knockdown or sitagliptin (inhibitor of DPP4)-mediated inhibition to assess the effects of DPP4 on the MAPK pathway and cellular processes, including proliferation, apoptosis, and epithelial-to-mesenchymal transition (EMT).

RESULTS

Intriguingly, our data revealed markedly high expression of DPP4 in PTC tissues. However, in GLAG-66 and TPC-1 cells, the silencing of DPP4 resulted in significantly reduced expression of ERK1/2, JNK1, P38 MAPK, VEGF, FGFR-1, TGF-β1, Snail, HIF-1α, N-cadherin, and Bcl-2 along with reduced phosphorylation of ERK1/2, JNK1, and P38 MAPK, whereas the expression of E-cadherin and Bax was increased. Furthermore, DPP4 silencing was found to hinder cell proliferation and potentiate cell apoptosis.

CONCLUSION

Collectively, the present study demonstrated that DPP4 gene silencing inhibits PTC cell proliferation and EMT and promotes cell apoptosis via suppression of the MAPK pathway, thus highlighting a possible regulatory pathway in PTC progression.

Effects of SGLT2 inhibitors on systemic and tissue low-grade inflammation: The potential contribution to diabetes complications and cardiovascular disease

Chronic low-grade inflammation is a recognized key feature associated with type 2 diabetes mellitus (T2DM) and its complications. In prospective randomized trials, sodium-glucose cotransporter type 2 (SGLT2) inhibitors have demonstrated benefits related to several cardiovascular and renal risk factors, including HbA_1c, blood pressure, body weight, renal hyperfiltration, and improvement of cardiorenal outcomes. SGLT2 inhibitors may improve adipose tissue function and induce decreases in serum leptin, TNF-α and IL-6 while increasing adiponectin. While data on high-sensitivity C-reactive protein and other inflammatory markers are relatively scarce in humans, in animals, a number of reports have shown reductions in cytokine and chemokine concentrations in parallel with protective effects against progression of atherosclerotic lesions. Experimental findings also suggest that part of the renoprotective effects of SGLT2 inhibition may be related to anti-inflammatory actions at the kidney level. Underlying mechanisms to explain this anti-inflammatory effect are multiple, but may involve weight loss, and reduction in adipose tissue inflammation, slight increase in ketone bodies and diminution of uric acid levels or attenuation of oxidative stress. However, further studies in diabetes patients with specific assessment of inflammatory markers are still necessary to determine the specific contribution of the anti-inflammatory action of SGLT2 inhibitors to the reduction of cardiovascular and renal complications and mortality observed with this class of antidiabetic drugs.

Long-term effects of sitagliptin in patients with type 2 diabetes mellitus and hypertension: results from the PROLOGUE study

Background

The effects of sitagliptin in patients with type 2 diabetes mellitus and hypertension are unclear. Therefore, we evaluated the long-term effects of sitagliptin in those patients.

Methods

In the PROLOGUE study, 365 patients were diagnosed as type 2 diabetes mellitus and hypertension, and 189 patients in the sitagliptin group, 176 patients in the conventional group. Fasting blood glucose (FBG), HbA1c, systolic pressure (SP), diastolic pressure (DP), serum urea nitrogen (BUN) and serum creatinine (SCR) were measured at the beginning of the study and after 12 and 24 months of treatment.

Results

FBS and HbA1c levels were not significantly decreased after treatment [12 months: OR: -3.1, 95% CI (-11.3, 5.0); OR: 0.1, 95% CI (0.0, 0.3); 24 months: OR: -0.1, 95% CI (-9.1, 8.8); OR: 0.1, 95% CI (0.0, 0.3), respectively]. BP and DP levels were not significantly decreased after treatment (12 months: OR: 0.9, 95% CI (-2.8, 4.6); OR: 0.6, 95% CI (-2.0, 3.2); 24 months: OR: -0.5, 95% CI (-4.2, 3.1); OR: -1.6, 95% CI (-41, 0.9), respectively]. Furthermore, BUN and SCR levels were not significantly decreased after treatment (12 months: OR: 0.0, 95%CI (-1.2, 1.2); OR: 0.0, 95% CI (-0.1, 0.0); 24 months: OR: 0.4, 95% CI (-1.0, 1.8); OR: -80.8, 95% CI (-201.3, 39.8), respectively]. After adjusting for confounding factors, our results did not change.

Conclusions

In our study, there was no evidence that treatment with sitagliptin can improve FBS, BP, DP, BUN or SCR in patients with type 2 diabetes mellitus and hypertension.

Trial Registration

University Hospital Medical Information Network Clinical Trials Registry UMIN000004490.

The persistent inhibitory properties of saxagliptin on renal dipeptidyl peptidase-4: Studies with HK-2 cells in vitro and normal rats in vivo

Saxagliptin, a potent and selective DPP-4 inhibitor, exhibits a slow dissociation from DPP-4. We investigated the sustained effects of saxagliptin on renal DPP-4 activity in a washout study using renal tubular (HK-2) cells, and in a pharmacodynamic study using normal rats. In HK-2 cells, the inhibitory potency of saxagliptin on DPP-4 activity persisted after washout, while that of sitagliptin was clearly reduced. In normal rats, a single treatment of saxagliptin or sitagliptin inhibited the plasma DPP-4 activity to similar levels. The inhibitory action of saxagliptin on the renal DPP-4 activity was retained, even when its inhibitory effect on the plasma DPP-4 activity disappeared. However, the inhibitory action of sitagliptin on the renal DPP-4 activity was abolished in correlation with the inhibition of the plasma DPP-4 activity. In situ staining showed that saxagliptin suppressed the DPP-4 activity in both glomerular and tubular cells and its inhibitory effects were significantly higher than those of sitagliptin. Saxagliptin exerted a sustained inhibitory effect on the renal DPP-4 activity in vitro and in vivo. The long binding action of saxagliptin in renal tubular cells might involve the sustained inhibition of renal DPP-4.

Dynamic Analysis of Kidney Function and Its Correlation with Nutritional Indicators in a Large Sample of Hospitalized Elderly Patients

Background

The aim of this study was to analyze changes in kidney function and its correlation with nutritional metabolism indicators in hospitalized elderly patients in a large medical center over the past 7 years.

Material/Methods

The renal function of patients over 60 years old in the Chinese PLA General Hospital in 2008, 2011, and 2014 were comparatively analyzed. The hemoglobin, serum albumin, triglycerides, cholesterol, uric acid, and urea nitrogen data were collected and used as the nutritional metabolism indicators. In addition, the correlation between these indicators and the eGFR was analyzed.

Results

The numbers of patients who received kidney function assessments in the 3 years were 15 752, 23 539, and 49 828; their mean ages were 69.97±6.99, 69.51±7.11, and 69.45±7.74 years. The median values of serum creatinine were 75.4, 76.5, and 77.5 μmol/L in the men and 59.6, 60.7, and 62.1 μmol/L in the women. The eGFR in both sexes demonstrated a gradual decreasing trend over the 3 years. According to the CKD staging method, analysis of the different percentages of eGFR intervals in the patients showed that the percentages of the 3 groups with an eGFR lower than 60 mL/min/1.73 m² exhibited a rising trend annually. Correlational analysis of the nutritional indicators showed that the correlations between Hb, ALB, TG, TC, Ur, and BUN with an eGFR lower than 60 mL/min/1.73 m² were 0.582, 0.780, 1.219, 1.364, 2.180, and 3.677, respectively.

Conclusions

Serum creatinine showed a gradually increasing trend over the 3 study years. The CKD-EPI equation calculation results showed that the eGFR in elderly people of both sexes gradually decreased. Reduction of hemoglobin and albumin was a risk factor for decreased kidney function, while increases in uric acid and blood lipids affected the progression of renal insufficiency.