Gliptins and their target dipeptidyl peptidase 4: implications for the treatment of vascular disease

The "entanglement" between bullous pemphigoid and diabetes mellitus: a comprehensive review and expert recommendations

INTRODUCTION

Bullous pemphigoid (BP) is an autoimmune bullous disease characterized by subepidermal tense blisters, accompanied by urticarial or eczema-like lesions. Circulating autoantibodies in BP patients target BP180 and BP230 at the dermal-epidermal junction. There has been a growing interest in unraveling the intricate relationship between BP and diabetes mellitus (DM), but a comprehensive review is lacking.

AREAS COVERED

A thorough search of PubMed was conducted to identify studies concerning the association between BP and DM (1978-2023). Our findings comprehensively summarize the intricate association between BP and DM, focusing on the characteristics, potential pathomechanisms, and the influence of various antidiabetic medications on BP development.

EXPERT OPINION

DM emerges as a prevalent comorbidity and potential risk factor for BP. New-onset DM can manifest during BP treatment, primarily due to corticosteroid therapy. Among all antidiabetic medications, dipeptidyl peptidase-IV inhibitors (DPP-4i) have the most solid association with BP onset. Other antidiabetic medications have also been reportedly associated with BP, including meglitinides, glucagon-like peptide 1 (GLP-1)-receptor agonists, and sodium-dependent glucose transporters 2 inhibitors (SGLT-2i). We suggest prescribing DPP-4i in caution for elderly DM patients with a history of autoimmune diseases.

A case of bullous pemphigoid and renal disease after dipeptidyl peptidase 4 inhibitor administration

A 62-year-old man with type 2 diabetes was admitted because of a decrease in estimated glomerular filtration rate from 72 to 17.5 mL/min/1.73 m2 in 10 years and development of widespread bullous skin lesions. His hemoglobin A1c level had been maintained at 6.0-7.0% for 10 years with a dipeptidyl peptidase (DPP)-4 inhibitor. Skin biopsy showed typical bullous pemphigoid, and kidney biopsy showed tubulointerstitial nephritis with eosinophilic infiltration and glomerular endothelial cell proliferation. After discontinuing the DPP-4 inhibitor, skin lesions improved, and renal decline slowed. This case indicates that DPP-4 inhibitors can cause not only skin lesions but also renal disease.

The OSR9 Regimen: A New Augmentation Strategy for Osteosarcoma Treatment Using Nine Older Drugs from General Medicine to Inhibit Growth Drive

As things stand in 2023, metastatic osteosarcoma commonly results in death. There has been little treatment progress in recent decades. To redress the poor prognosis of metastatic osteosarcoma, the present regimen, OSR9, uses nine already marketed drugs as adjuncts to current treatments. The nine drugs in OSR9 are: (1) the antinausea drug aprepitant, (2) the analgesic drug celecoxib, (3) the anti-malaria drug chloroquine, (4) the antibiotic dapsone, (5) the alcoholism treatment drug disulfiram, (6) the antifungal drug itraconazole, (7) the diabetes treatment drug linagliptin, (8) the hypertension drug propranolol, and (9) the psychiatric drug quetiapine. Although none are traditionally used to treat cancer, all nine have attributes that have been shown to inhibit growth-promoting physiological systems active in osteosarcoma. In their general medicinal uses, all nine drugs in OSR9 have low side-effect risks. The current paper reviews the collected data supporting the role of OSR9.

DSC, FT-IR and NIR with Chemometric Assessment Using PCA and HCA for Estimation of the Chemical Stability of Oral Antidiabetic Drug Linagliptin in the Presence of Pharmaceutical Excipients

Pharmaceutical excipients should not interact with active substances, however, in practice, they sometimes do it, affecting the efficacy, stability and safety of drugs. Thus, interactions between active substances and excipients are not desirable. For this reason, two component mixtures of oral antidiabetic drug linagliptin (LINA) with four excipients of different reactivity, i.e., lactose (LAC), mannitol (MAN), magnesium stearate (MGS) and polyvinylpyrrolidone (PVP), were prepared in a solid state. A high temperature and a high humidity of 60 °C and 70% RH, respectively, were applied as stressors in order to accelerate the potential interactions between LINA and excipients. Differential scanning calorimetry (DSC) as well as Fourier transform infrared (FT-IR) and near infrared (NIR) spectroscopy were used to estimate the changes due to potential interactions. In addition, chemometric computation of the data with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to adequately interpret the findings. Of the excipients used in the present experiment, all of them were not inert in relation to LINA. Some of the interactions were shown without any stressing, whereas others were observed under high-temperature/high-humidity conditions. Thus, it could be concluded that selection of appropriate excipients for LINA is very important question to minimize its degradation, especially when new types of formulations with LINA are being developed and manufactured.

Gliptin-associated bullous pemphigoid shows peculiar features of anti-BP180 and -BP230 humoral response: results from a multicenter study

BACKGROUND

Recently, several case-control studies demonstrated an association between gliptins and bullous pemphigoid (BP) occurrence. Data on clinical and immunological features of gliptin-associated bullous pemphigoid (GABP) are controversial.

OBJECTIVE

This study aims to clinically and immunologically characterize a large cohort of GABP patients to get insight into the pathophysiology of this emerging drug-induced variant of BP.

METHODS

Seventy-four GABP patients were prospectively enrolled and characterized from nine different Italian Dermatology Units between 2013 and 2020.

RESULTS

Our findings demonstrate that in GABP patients: i) the non-inflammatory phenotype which is characterized by low amounts of circulating and skin infiltrating eosinophils is frequently found; ii) IgG, IgE and IgA humoral response to BP180 and BP230 antigens is reduced in frequency and titers when compared with idiopathic BP; iii) IgG reactivity targets multiple BP180 epitopes other than NC16A.

LIMITATIONS

A limitation of the study is the control group that did not comprise only type 2 diabetes mellitus BP patients.

CONCLUSIONS

GABP patients show peculiar features of anti-BP180 and -BP230 humoral response laying the foundations for diagnostic improvements and to get novel insights into understanding the mechanism of BP onset.

Evaluation of Risk of Bullous Pemphigoid With Initiation of Dipeptidyl Peptidase-4 Inhibitor vs Second-generation Sulfonylurea

Importance

Despite several recent reports on the elevated risk of bullous pemphigoid in patients with type 2 diabetes treated with dipeptidyl peptidase-4 (DPP-4) inhibitors, evidence on the absolute risk and comparative safety against other antidiabetics is limited.

Objective

To characterize the incidence rate of bullous pemphigoid associated with DPP-4 inhibitor use compared with second-generation sulfonylureas.

Design, Setting, and Participants

This cohort study used data from 2 large commercial insurance claims databases (Optum Clinformatics Data Mart from October 17, 2006, to December 31, 2018, and IBM MarketScan Research Database from October 17, 2006, to December 31, 2017) and Medicare data from January 1, 2006, to December 31, 2016. Patients with type 2 diabetes who initiated treatment with DPP-4 inhibitors or second-generation sulfonylurea were included.

Main Outcomes and Measures

The primary outcome of the study was bullous pemphigoid, identified using diagnosis codes. After 1:1 propensity score matching, the incidence rates of bullous pemphigoid and the hazard ratios (HRs) with 95% CIs comparing patients who initiated DPP-4 inhibitor and second-generation sulfonylurea therapy were estimated. Subgroup analyses by age, sex, race, and individual DPP-4 agents were performed. The results from each database were pooled using inverse-variance fixed-effects meta-analysis.

Results

A total of 1 664 880 patients who initiated DPP-4 inhibitors (51.0% female; mean [SD] age, 63.9 [9.7] years) and sulfonylurea (50.4% female; mean [SD] age, 63.9 [9.9] years) were included. The incidence rate of bullous pemphigoid per 1000 person-years was 0.42 in the DPP-4 inhibitor group vs 0.31 in the sulfonylurea group (HR, 1.42; 95% CI, 1.17-1.72). Higher rates per 1000 person-years for DPP-4 inhibitor vs sulfonylurea groups were seen in those who were 65 years or older (0.79 vs 0.49; HR, 1.62; 95% CI, 1.32-1.99), white (0.93 vs 0.54; HR, 1.70; 95% CI, 1.30-2.24), and treated with linagliptin (1.20 vs 0.55; HR, 1.68; 95% CI, 1.16-2.43).

Conclusions and Relevance

This study found that patients who initiated DPP-4 inhibitor therapy had higher risk of bullous pemphigoid than those who initiated second-generation sulfonylurea therapy. Clinicians should be aware of this rare adverse effect of DPP-4 inhibitors in subgroups of patients who are older, white, and linagliptin users.

Therapies for the Treatment of Cardiovascular Disease Associated with Type 2 Diabetes and Dyslipidemia

Cardiovascular disease (CVD) is the leading cause of death worldwide and is the clinical manifestation of the atherosclerosis. Elevated LDL-cholesterol levels are the first line of therapy but the increasing prevalence in type 2 diabetes mellitus (T2DM) has positioned the cardiometabolic risk as the most relevant parameter for treatment. Therefore, the control of this risk, characterized by dyslipidemia, hypertension, obesity, and insulin resistance, has become a major goal in many experimental and clinical studies in the context of CVD. In the present review, we summarized experimental studies and clinical trials of recent anti-diabetic and lipid-lowering therapies targeted to reduce CVD. Specifically, incretin-based therapies, sodium-glucose co-transporter 2 inhibitors, and proprotein convertase subtilisin kexin 9 inactivating therapies are described. Moreover, the novel molecular mechanisms explaining the CVD protection of the drugs reviewed here indicate major effects on vascular cells, inflammatory cells, and cardiomyocytes, beyond their expected anti-diabetic and lipid-lowering control. The revealed key mechanism is a prevention of acute cardiovascular events by restraining atherosclerosis at early stages, with decreased leukocyte adhesion, recruitment, and foam cell formation, and increased plaque stability and diminished necrotic core in advanced plaques. These emergent cardiometabolic therapies have a promising future to reduce CVD burden.

The Impact of Antidiabetic Therapies on Diastolic Dysfunction and Diabetic Cardiomyopathy

Diabetic cardiomyopathy is more prevalent in people with type 2 diabetes mellitus (T2DM) than previously recognized, while often being characterized by diastolic dysfunction in the absence of systolic dysfunction. This likely contributes to why heart failure with preserved ejection fraction is enriched in people with T2DM vs. heart failure with reduced ejection fraction. Due to revised mandates from major health regulatory agencies, all therapies being developed for the treatment of T2DM must now undergo rigorous assessment of their cardiovascular risk profiles prior to approval. As such, we now have data from tens of thousands of subjects with T2DM demonstrating the impact of major therapies including the sodium-glucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dipeptidyl peptidase 4 (DPP-4) inhibitors on cardiovascular outcomes. Evidence to date suggests that both SGLT2 inhibitors and GLP-1R agonists improve cardiovascular outcomes, whereas DPP-4 inhibitors appear to be cardiovascular neutral, though evidence is lacking to determine the overall utility of these therapies on diastolic dysfunction or diabetic cardiomyopathy in subjects with T2DM. We herein will review the overall impact SLGT2 inhibitors, GLP-1R agonists, and DPP-4 inhibitors have on major parameters of diastolic function, while also highlighting the potential mechanisms of action responsible. A more complete understanding of how these therapies influence diastolic dysfunction will undoubtedly play a major role in how we manage cardiovascular disease in subjects with T2DM.

Livedoid and Purpuric Skin Eruptions Associated With Coagulopathy in Severe COVID-19

Question

What is the absolute risk of bullous pemphigoid in patients who initiate use of dipeptidyl peptidase–4 inhibitors and its comparative risk against sulfonylurea use?

Findings

In this cohort study of 1 664 880 patients with type 2 diabetes, the incidence rate of bullous pemphigoid per 1000 person-years among patients who initiated dipeptidyl peptidase–4 inhibitor therapy was 0.42 compared with 0.31 for sulfonylurea. The risk was 42% higher with dipeptidyl peptidase–4 inhibitors than with sulfonylurea and 62% to 70% higher in subgroups of patients who were 65 years or older, white, and linagliptin users.

Meaning

These findings suggest that use of dipeptidyl peptidase–4 inhibitors is associated with higher risk of bullous pemphigoid compared with sulfonylurea, and that clinicians should be aware of this rare adverse effect in subgroups with higher risk.

Importance

Despite several recent reports on the elevated risk of bullous pemphigoid in patients with type 2 diabetes treated with dipeptidyl peptidase–4 (DPP-4) inhibitors, evidence on the absolute risk and comparative safety against other antidiabetics is limited.

Objective

To characterize the incidence rate of bullous pemphigoid associated with DPP-4 inhibitor use compared with second-generation sulfonylureas.

Design, Setting, and Participants

This cohort study used data from 2 large commercial insurance claims databases (Optum Clinformatics Data Mart from October 17, 2006, to December 31, 2018, and IBM MarketScan Research Database from October 17, 2006, to December 31, 2017) and Medicare data from January 1, 2006, to December 31, 2016. Patients with type 2 diabetes who initiated treatment with DPP-4 inhibitors or second-generation sulfonylurea were included.

Main Outcomes and Measures

The primary outcome of the study was bullous pemphigoid, identified using diagnosis codes. After 1:1 propensity score matching, the incidence rates of bullous pemphigoid and the hazard ratios (HRs) with 95% CIs comparing patients who initiated DPP-4 inhibitor and second-generation sulfonylurea therapy were estimated. Subgroup analyses by age, sex, race, and individual DPP-4 agents were performed. The results from each database were pooled using inverse-variance fixed-effects meta-analysis.

Results

A total of 1 664 880 patients who initiated DPP-4 inhibitors (51.0% female; mean [SD] age, 63.9 [9.7] years) and sulfonylurea (50.4% female; mean [SD] age, 63.9 [9.9] years) were included. The incidence rate of bullous pemphigoid per 1000 person-years was 0.42 in the DPP-4 inhibitor group vs 0.31 in the sulfonylurea group (HR, 1.42; 95% CI, 1.17-1.72). Higher rates per 1000 person-years for DPP-4 inhibitor vs sulfonylurea groups were seen in those who were 65 years or older (0.79 vs 0.49; HR, 1.62; 95% CI, 1.32-1.99), white (0.93 vs 0.54; HR, 1.70; 95% CI, 1.30-2.24), and treated with linagliptin (1.20 vs 0.55; HR, 1.68; 95% CI, 1.16-2.43).

Conclusions and Relevance

This study found that patients who initiated DPP-4 inhibitor therapy had higher risk of bullous pemphigoid than those who initiated second-generation sulfonylurea therapy. Clinicians should be aware of this rare adverse effect of DPP-4 inhibitors in subgroups of patients who are older, white, and linagliptin users.

Clinical and immunological profile of patients with dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune blistering disease caused by antibodies against the hemidesmosomal BP180 and/or BP230 proteins. There is an increasing evidence that the use of dipeptidyl peptidase-4 inhibitors, also known as gliptins, increases the risk for BP. The gliptins more frequently associated with BP are vildagliptin and sitagliptin. Clinical, immunological and pathological features of gliptin-associated BP have been reported to be distinct, compared to classic BP.

METHODS

In this study, 15 gliptin-associated BP (g-BP) cases have been compared with 16 consecutive idiopathic BP (i-BP) to clarify whether g-BP has distinctive clinical and immunopathological characteristics. Comorbidities, concomitant treatments, latency of the onset of the disease and the time to achieve the remission were also considered.

RESULTS

The mean latency from drug intake to g-BP appearance was 9.4 months (median 10, inter-quartile range [IQR] 6-12). There were no differences in sex and age prevalence between the two groups (g-BP median age 77 years, IQR: 70-84; i-BP: 81 years, IQR: 72-86). There were no differences as far clinical presentation including disease severity, lesions types (urticarial and bullous) or mucosal involvement between g-BP and i-BP cases. The median antibody anti-BP180 and anti-BP230 titers was also similar between the two groups with 29.1 UI/mL (IQR: 12.9-65.3) and 11.8 UI/mL (IQR: 1.7-26.3), respectively. Gliptins were withdrawn in ten out of 15 patients and remission was achieved with systemic corticosteroids (0.3-0.7 mg/Kg daily) alone or in association with doxycycline (100-200 mg daily) within a mean of 8 months.

CONCLUSIONS

A non-inflammatory phenotype with less erythema, fewer urticarial lesions and fewer eosinophils in skin lesions has been associated with gliptins in selected Japanese BP populations. As reported in European studies, no significant differences among the considered variables in the g-BP and i-BP cases have been found in our study.

Identification of a Novel Scaffold for Inhibition of Dipeptidyl Peptidase-4

Dipeptidyl peptidase-4 (DPP-4) is considered a major drug target for type 2 diabetes mellitus (T2DM). In addition to T2DM, a regulatory role of DPP-4 was also found in cardiovascular diseases. Existing DPP-4 inhibitors have been reported to have several adverse effects. In this study, a computer-aided drug design approach and its use to detect a novel class of inhibitor for DPP-4 are reported. Through structure and pharmacophore-based screening, we identified 13 hit compounds from an ∼4-million-compound library. Physical interactions of these hits with DPP-4 were studied using docking and explicit solvent molecular dynamics (MD) simulations. Later, MMPBSA binding energy was calculated for the ligand/protein simulation trajectories to determine the stability of compounds in the binding cavity. These compounds have a novel scaffold and exhibited a stable binding mode. "Best-in-screen" compounds (or their closest available analogs) were resourced and their inhibition of DPP-4 activity was experimentally validated using an in vitro enzyme activity assay in the presence of 100 and 10 μM compounds. These assays identified a compound with a spirochromanone center with 53% inhibition activity at a 100 μM concentration. A further five spirochromanone compounds were synthesized and examined in silico and in vitro; again, one compound showed 53% inhibitory activity action at 100 μM. Overall, this study identified two novel "spirochromanone" compounds that lowered DPP-4 activity by more than ∼50% at 100 μM. This study also showed the impact of fast in silico drug design techniques utilizing virtual screening and MD to identify novel scaffolds to bind and inhibit DPP-4. Spirochromanone motif identified here may be used to design molecules to achieve drug-like inhibitory action against DPP-4.

[Drug-induced angioedema : Focus on bradykinin]

On a pathophysiological level, angioedema can be differentiated into histamine- and bradykinin-mediated types. The prototype drug-associated, bradykinin-mediated form of angioedema is angiotensin-converting enzyme (ACE) inhibitor-induced angioedema. The hypothesized cause is a decrease in bradykinin degradation via ACE inhibition. In this scenario, other bradykinin-degrading enzymes assume major importance. When the effect of these enzymes is also diminished, e. g., due to genetic variants or external factors, compensation for the inhibition of ACE may be insufficient. An increased risk of angioedema has also been reported for other drugs, particularly when prescribed in combination with ACE inhibitors. Here, the suspected cause also relates to the degradation of bradykinin. When angioedema arises within the context of concomitant ACE inhibitor use, additive bradykinin degradation effects may be implicated.

Dipeptidyl Peptidase-4 Inhibitor-Associated Bullous Pemphigoid

Bullous pemphigoid (BP) is an organ-specific autoantibody-mediated blistering skin disease that mainly affects the elderly. Typical clinical features include the widespread blisters, often preceded by and/or associated with itchy urticarial or eczema-like lesions. BP patients have circulating autoantibodies against BP180 and/or the plakin family protein BP230 both of which are components of hemidesmosomes in basal keratinocytes. Most BP autoantibodies particularly target the epitopes within the non-collagenous NC16A domain of BP180. Clinical findings and murine models of BP have provided evidence of a pathogenic role of anti-NC16A autoantibodies. However, it is largely unknown what triggers the breakage of immunotolerance against BP180 in elderly individuals. The incidence of BP has been increased over the past two decades in several countries. Aside from aging populations, the factors behind this phenomenon are still not fully understood. Neurodegenerative diseases such as multiple sclerosis, Parkinson's disease, and certain dementias are independent risk factors for BP. Recently several case reports have described BP in patients with diabetes mellitus (DM) patients who have been treated with dipeptidyl peptidase-4 inhibitors (DPP-4i or gliptins), which are a widely used class of anti-DM drugs. The association between the use of DPP-4is, particularly vildagliptin, and BP risk has been confirmed by several epidemiological studies. Evidence suggests that cases of gliptin-associated BP in Japan display certain features that set them apart from cases of “regular” BP. These include a “non-inflammatory” phenotype, targeting by antibodies of different immunodominant BP180 epitopes, and a specific association with the human leukocyte antigen (HLA) types. However, recent studies in European populations have found no major differences between the clinical and immunological characteristics of gliptin-associated BP and “regular” BP. The DPP-4 protein (also known as CD26) is ubiquitously expressed and has multiple functions in various cell types. The different effects of the inhibition of DPP-4/CD26 activity include, for example, tissue modeling and regulation of inflammatory cells such as T lymphocytes. Although the pathomechanism of gliptin-associated BP is currently largely unknown, investigation of the unique effect of gliptins in the induction of BP may provide a novel route to better understanding of how immunotolerance against BP180 breaks down in BP.

Teneligliptin inhibits lipopolysaccharide-induced cytotoxicity and inflammation in dental pulp cells

Diabetes mellitus is one of the most common health threatening disorders. Patients with chronic diabetes are at high risk of contracting oral diseases, including dental pulp damage. In this study, we reviewed how Teneligliptin, a commonly used anti-diabetic agent, protected dental pulp cells from lipopolysaccharide (LPS)-induced cytotoxicity and improved their viability. The dental pulp cells treated with Teneligliptin were resistant to LPS-induced reactive oxygen species (ROS) and its byproduct 4-hydroxynonenal (4-HNE) generation. The Teneligliptin recovered LPS-induced a reduction of cellular glutathione and produced cytokine including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Mechanistically, we found that Teneligliptin suppressed LPS- that caused an expression of the cell surface receptor toll like receptor 4 (TLR-4) and the activation of JNK kinase and activator protein 1 (AP1) as well as the nuclear factor-κB (NF-κB) signal pathways. Collectively, our study demonstrates that the molecular mechanism Teneligliptin is a protective anti-diabetic agent in dental pulp cells and it has the potential to treat diabetes-associated dental pulp diseases.

Sitagliptin Accelerates Endothelial Regeneration after Vascular Injury Independent from GLP1 Receptor Signaling

INTRODUCTION

DPP4 inhibitors (gliptins) are commonly used antidiabetic drugs for the treatment of type 2 diabetes. Gliptins also act in a glucose-independent manner and show vasoregenerative effects. We have shown that gliptins can remarkably accelerate vascular healing after vascular injury. However, the underlying mechanisms remain unclear. Here, we examined potential signaling pathways linking gliptins to enhanced endothelial regeneration.

METHODS AND RESULTS

We used wild-type and GLP1 receptor knockout (Glp1r-/-) mice to investigate the underlying mechanisms of gliptin-induced reendothelialization. The prototype DPP4 inhibitor sitagliptin accelerated endothelial healing in both animal models. Improved endothelial growth was associated with gliptin-mediated progenitor cell recruitment into the diseased vascular wall via the SDF1-CXCR4 axis independent of GLP1R-dependent signaling pathways. Furthermore, SDF1 showed direct proproliferative effects on endothelial cells. Excessive neointimal formation was not observed in gliptin- or placebo-treated Glp1r-/- mice.

CONCLUSION

We identified the SDF1-CXCR4 axis as a crucial signaling pathway for endothelial regeneration after acute vascular injury. Furthermore, SDF1 can directly increase endothelial cell proliferation. Gliptin-mediated potentiation of endothelial regeneration was preserved in Glp1r-/- animals. Thus, gliptin-mediated endothelial regeneration proceeds through SDF-1/CXCR4 in a GLP1R-independent manner after acute vascular injury.

Vildagliptin ameliorates pulmonary fibrosis in lipopolysaccharide-induced lung injury by inhibiting endothelial-to-mesenchymal transition

BACKGROUND

Pulmonary fibrosis is a late manifestation of acute respiratory distress syndrome (ARDS). Sepsis is a major cause of ARDS, and its pathogenesis includes endotoxin-induced vascular injury. Recently, endothelial-to-mesenchymal transition (EndMT) was shown to play an important role in pulmonary fibrosis. On the other hand, dipeptidyl peptidase (DPP)-4 was reported to improve vascular dysfunction in an experimental sepsis model, although whether DPP-4 affects EndMT and fibrosis initiation during lipopolysaccharide (LPS)-induced lung injury is unclear. The aim of this study was to investigate the anti-EndMT effects of the DPP-4 inhibitor vildagliptin in pulmonary fibrosis after systemic endotoxemic injury.

METHODS

A septic lung injury model was established by intraperitoneal injection of lipopolysaccharide (LPS) in eight-week-old male mice (5 mg/kg for five consecutive days). The mice were then treated with vehicle or vildagliptin (intraperitoneally, 10 mg/kg, once daily for 14 consecutive days from 1 day before the first administration of LPS.). Flow cytometry, immunohistochemical staining, and quantitative polymerase chain reaction (qPCR) analysis was used to assess cell dynamics and EndMT function in lung samples from the mice.

RESULTS

Lung tissue samples from treated mice revealed obvious inflammatory reactions and typical interstitial fibrosis 2 days and 28 days after LPS challenge. Quantitative flow cytometric analysis showed that the number of pulmonary vascular endothelial cells (PVECs) expressing alpha-smooth muscle actin (α-SMA) or S100 calcium-binding protein A4 (S100A4) increased 28 days after LPS challenge. Similar increases in expression were also confirmed by qPCR of mRNA from isolated PVECs. EndMT cells had higher proliferative activity and migration activity than mesenchymal cells. All of these changes were alleviated by intraperitoneal injection of vildagliptin. Interestingly, vildagliptin and linagliptin significantly attenuated EndMT in the absence of immune cells or GLP-1.

CONCLUSIONS

Inhibiting DPP-4 signaling by vildagliptin could ameliorate pulmonary fibrosis by downregulating EndMT in systemic LPS-induced lung injury.

Plasma dipeptidyl-peptidase-4 activity is associated with left ventricular systolic function in patients with ST-segment elevation myocardial infarction

Plasma dipeptidyl-peptidase-4 activity (DPP4a) is inversely associated with left ventricular function in patients with heart failure (HF) or diabetes. However, the association between DPP4a and left ventricular function in ST-segment elevation myocardial infarction (STEMI) patients has not been reported. We studied this association in 584 consecutive STEMI patients at a tertiary referral center from July 2014 to October 2015. DPP4a and plasma N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) levels were quantified by enzymatic assays. The median serum NT-proBNP levels were highest in patients of the lowest tertile (T1) of DPP4a compared with that of the highest tertile (T3) (p = 0.028). The STEMI patients in T1 exhibited lower left ventricular systolic function (T1 vs. T3: left ventricular ejection fraction (LVEF): 50.13 ± 9.12 vs. 52.85 ± 6.82%, p = 0.001). Multivariate logistic-regression analyses (adjusted for confounding variables) showed that a 1 U/L increase in DPP4a was associated with a decreased incidence of left ventricular systolic dysfunction (LVSD) (adjusted odds ratio: 0.90; 95% CI: 0.87–0.94; p < 0.01). In conclusion, low DPP4a is independently associated with LVSD in STEMI patients, which suggests that DPP4 may be involved in the mechanisms of LVSD in STEMI patients.

The regulatory role of DPP4 in atherosclerotic disease

The increasing prevalence of atherosclerosis has become a worldwide health concern. Although significant progress has been made in the understanding of atherosclerosis pathogenesis, the underlying mechanisms are not fully understood. Recent studies suggest dipeptidyl peptidase-4 (DPP4), a regulator of inflammation and metabolism, may be involved in the development of atherosclerotic diseases. There has been increasing clinical and pre-clinical evidence showing DPP4-incretin axis is involved in cardiovascular disease. Although the cardiovascular outcome of DPP4 inhibition or incretin analogues has been or being evaluated by several large scale clinical trials, the exact role of DPP4 in atherosclerotic diseases is not completely understood. In the current review, we will summarize the recent advances in direct and indirect regulatory role of DPP4 in atherosclerosis.

PEDF improves atherosclerotic plaque stability by inhibiting macrophage inflammation response

BACKGROUND

Atherosclerosis is a vascular disease with plaque formation and growth. Instable plaque with chronic inflammation is closely related to adverse cardiac outcomes. Pigment epithelium-derived factor (PEDF) is an endogenous multifunctional cytokine that possesses the ability of anti-inflammation. The aim of this study is to detect whether PEDF has protective effect on the stability of atherosclerotic plaque and to explore whether the effect of anti-inflammation involved.

METHODS AND RESULTS

ApoE^-/- mice fed with high fat diet and RAW264.7 cells were used to evaluate anti-inflammatory activities of PEDF both in vivo and in vitro. PEDF overexpression improved atherosclerotic plaque stability in ApoE^-/- mice. The expression of inflammatory factors (interleukin-1β [IL-1β], interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α], monocyte chemotactic protein-1 [MCP-1] and matrix metalloproteinase [MMP-9]) was significantly decreased with PEDF overexpression in vivo and in vitro. The anti-inflammation effect of PEDF was attenuated by PPAR-γ specific antagonist GW9662. In addition, PEDF significantly decreased the expression of phosphorylated ERK-MAPK, p38-MAPK and JNK-MAPK. GW9662 partly reversed the PEDF-mediated depression of phosphorylated ERK- and p38-MAPK but has no significant effect on JNK-MAPK.

CONCLUSIONS

PEDF has protective effect on increasing AS plaque stability through ameliorating macrophage inflammation. PPAR-γ and downstream MAPKs were involved in the mechanism.