Emerging Role of Dipeptidyl Peptidase-4 in Autoimmune Disease

Chromium and formoterol therapy for obesity-induced asthma in rats

The development of asthma is impacted by fat. Asthma is more common in obese persons. The purpose of the experimental study is to determine how chromium, formoterol, and their combination can improve the quality of life for obese people with lung anomalies. Thirty-six male Wistar rats were divided into six groups: control (C), obesity (CO), obese-asthma (COA), and obese-asthma groups treated with formoterol (OAF), chromium (OACR), or both (OACRF). Except for group C, all groups received a high-fat diet for 4 weeks. Subsequently, ovalbumin (OVA) was administered subcutaneously (s.c.) to all groups except C and CO to induce sensitization. Asthma was triggered via 1% OVA aerosol challenges on days 26-28. Over 5 days, OAF and OACRF received daily formoterol inhalations (50 μg/kg), while OACR and OACRF were given chromium (400 μg/kg). Treatments were timed to align with asthma induction protocols. Lipid profile and inflammatory indicators were examined at the end of the trial-Immunohistochemical analysis of lung tissue, Histopathological and lung tissue stained with Hematoxylin and Eosin. The combination therapy (OACRF) significantly reduced body weight (p < 0.05), lowered LDL and triglycerides, increased HDL, and normalized lung tissue architecture compared to controls. Immunohistochemistry revealed reduced IL-1β and IL-17α expression. The (OACRF) group demonstrated superior asthma control by reducing body weight, improving inflammatory indicators, and restoring lung tissue to its normal state by administering chromium and formoterol therapy. The most effective strategy for treating both obesity and asthma is to address their two connected conditions. These findings demonstrate that combined chromium and formoterol therapy effectively addresses metabolic and inflammatory components of obesity-induced asthma, offering a promising dual-target therapeutic strategy.

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.

Pig jejunal single-cell RNA landscapes revealing breed-specific immunology differentiation at various domestication stages

Background

Domestication of wild boars into local and intensive pig breeds has driven adaptive genomic changes, resulting in significant phenotypic differences in intestinal immune function. The intestine relies on diverse immune cells, but their evolutionary changes during domestication remain poorly understood at single-cell resolution.

Methods

We performed single-cell RNA sequencing (scRNA-seq) and marker gene analysis on jejunal tissues from wild boars, a Chinese local breed (Jinhua), and an intensive breed (Duroc). Then, we developed an immune cell evaluation system that includes immune scoring, gene identification, and cell communication analysis. Additionally, we mapped domestication-related clustering relationships, highlighting changes in gene expression and immune function.

Results

We generated a single-cell atlas of jejunal tissues, analyzing 26,246 cells and identifying 11 distinct cell lineages, including epithelial and plasma cells, and discovered shared and unique patterns in intestinal nutrition and immunity across breeds. Immune cell evaluation analysis confirmed the conservation and heterogeneity of immune cells, manifested by highly conserved functions of immune cell subgroups, but wild boars possess stronger immune capabilities than domesticated breeds. We also discovered four patterns of domestication-related breed-specific genes related to metabolism, immune surveillance, and cytotoxic functions. Lastly, we identified a unique population of plasma cells with distinctive antibody production in Jinhua pig population.

Conclusions

Our findings provide valuable single-cell insights into the cellular heterogeneity and immune function evolution in the jejunum during pig at various domestication stages. The single-cell atlas also serves as a resource for comparative studies and supports breeding programs aimed at enhancing immune traits in pigs.

Targeting osteoclast-derived DPP4 alleviates inflammation-mediated ectopic bone formation in ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by ectopic bone formation. The anti-inflammatory function of dipeptidyl peptidase-4 (DPP4) inhibitor has been reported in bone metabolism, but its utility in AS has not previously been investigated.

METHODS

We assessed DPP4 level in serum, synovial fluid, and facet joint tissue of AS patients. Additionally, we investigated the effect of a DPP4 inhibitor in an experimental AS model using curdlan-injected SKG mice. Following curdlan injection, SKG mice were orally administered a DPP4 inhibitor three times per week for 5 weeks and observed clinical arthritis scores, and analyzed by micro-CT. Furthermore, osteoclast precursor cells (OPCs) from curdlan-injected SKG mice were treated with DPP4 inhibitor and evaluated the inhibitory effects of this treatment in vitro.

RESULTS

Soluble DPP4 level was elevated in the serum and synovial fluid of patients with AS compared to those in the control group. Expression of DPP4 increased gradually during human osteoclastogenesis and was high in mature osteoclasts. Oral administration of a DPP4 inhibitor resulted in a decrease in thickness of the hind paw, clinical arthritis scores, and enthesitis at the ankle in curdlan-injected SKG mice compared to the vehicle group. Micro-CT data revealed a significant reduction in inflammation-induced low bone density in the DPP4 inhibitor group. Moreover, treatment with a DPP4 inhibitor significantly reduced osteoclast differentiation of OPC in addition to decreasing expression of osteoclast differentiation markers.

CONCLUSION

Our findings suggest that inhibiting DPP4 may have a therapeutic effect on inflammation-mediated ectopic bone formation in AS patients.

A case of immunoglobulin G4-related kidney disease manifesting after dipeptidyl peptidase-4 inhibitor treatment

A 68-year-old man with type 2 diabetes mellitus was admitted with decreased renal function. He had high IgG4 (1070 mg/dL) and hypocomplementemia (CH50, 25 U/mL). Kidney biopsy showed tubulointerstitial nephritis with IgG4-positive plasma cell infiltration. Four years later, a second kidney biopsy revealed a new manifestation of membranous nephropathy and tubulointerstitial nephritis with exacerbated fibrosis formation. Six years later, the patient developed bullous pemphigoid, which was thought to be caused by DPP4 inhibitors, so DPP4 inhibitor treatment was discontinued. The use of DPP4 inhibitors correlated with changes in renal function, and the patient was diagnosed with IgG4-related kidney disease related to DPP4 inhibitors.

Association of Gut Microbiome and Dipeptidyl Peptidase 4 in Immune-Mediated Inflammatory Bowel Disease: A Rapid Literature Review

Immune-mediated inflammatory diseases (IMIDs) are characterized by dysregulated immune responses and chronic tissue inflammation. In the setting of inflammatory bowel disease (IBD), dipeptidyl peptidase 4 (DPP4) and gut microorganisms have been proved to interplay, potentially influenced by dietary factors. This rapid review aimed to study the DPP4-gut microbiome link in IBD. A search across five databases and two gray literature sources identified seven relevant studies reporting data on DPP4 and gut microbiome in patients with IBD-related IMIDs or in vitro or in vivo models: one cross-sectional, one in vitro, and five in vivo studies. The findings revealed a significant impact of DPP4 and its substrates, i.e., glucagon-like peptide-1/2 (GLP-1/2), on the composition of gut microbiome and on the development of dysbiosis. Increased DPP4 activity is associated with decreased GLP-1/2; increased pathogenic bacterial phyla such as Actinobacteria, Bacteroidetes, Deferribacteres, Firmicutes, Fusobacteriota, Proteobacteria, and Verrucomicrobia; and decreased alpha diversity of beneficial gut microbes, including Clostridiaceae, Lachnospiraceae, and Ruminococcaceae families and short-chain fatty acid-producing bacteria like Odoribacter and Butryvibrio spp., with exacerbation of intestinal inflammation. This overview revealed that understanding the DPP4-gut microbiome association is critical for the development of DPP4-targeted therapeutic strategies to guarantee gut microbiome balance and modulation of immune response in IBD.

Therapeutic targeting of senescent cells in the CNS

Senescent cells accumulate throughout the body with advanced age, diseases and chronic conditions. They negatively impact health and function of multiple systems, including the central nervous system (CNS). Therapies that target senescent cells, broadly referred to as senotherapeutics, recently emerged as potentially important treatment strategies for the CNS. Promising therapeutic approaches involve clearing senescent cells by disarming their pro-survival pathways with 'senolytics'; or dampening their toxic senescence-associated secretory phenotype (SASP) using 'senomorphics'. Following the pioneering discovery of first-generation senolytics dasatinib and quercetin, dozens of additional therapies have been identified, and several promising targets are under investigation. Although potentially transformative, senotherapies are still in early stages and require thorough testing to ensure reliable target engagement, specificity, safety and efficacy. The limited brain penetrance and potential toxic side effects of CNS-acting senotherapeutics pose challenges for drug development and translation to the clinic. This Review assesses the potential impact of senotherapeutics for neurological conditions by summarizing preclinical evidence, innovative methods for target and biomarker identification, academic and industry drug development pipelines and progress in clinical trials.

New Insights into the Pleiotropic Actions of Dipeptidyl Peptidase-4 Inhibitors Beyond Glycaemic Control

Dipeptidyl peptidase-4 (DPP-4) is a multifunctional serine ectopeptidase that cleaves and modifies a plethora of substrates, including regulatory peptides, cytokines and chemokines. DPP-4 is implicated in the regulation of immune response, viral entry, cellular adhesion, metastasis and chemotaxis. Regarding its numerous substrates and extensive expression inside the body, multitasking DPP-4 has been assumed to participate in different pathophysiological mechanisms. DPP-4 inhibitors or gliptins are increasingly used for the treatment of type 2 diabetes mellitus. Several reports from experimental and clinical studies have clarified that DPP-4 inhibitors exert many beneficial pleiotropic effects beyond glycaemic control, which are mediated by anti-inflammatory, anti-oxidant, anti-fibrotic and anti-apoptotic actions. The present review will highlight the most recent findings in the literature about these pleiotropic effects and the potential mechanisms underlying these benefits, with a specific focus on the potential effectiveness of DPP-4 inhibitors in coronavirus disease-19 and diabetic kidney disease.

Commentary on "Structural characterization of SLYM - a 4th meningeal membrane"

For centuries, the meninges have been described as three membranes: the inner pia, middle arachnoid and outer dura. It was therefore sensational when in early 2023 Science magazine published a report of a previously unrecognized - 4th - meningeal membrane located between the pia and arachnoid. Multiple features were claimed for this new membrane: a single cell layer marked by the transcription factor Prox1 that formed a barrier to low molecular weight substances and separated the subarachnoid space (SAS) into two fluid-filled compartments, not one as previously described. These features were further claimed to facilitate unidirectional glymphatic cerebrospinal fluid transport. These claims were immediately questioned by several researchers as misinterpretations of the authors' own data. The critics argued that (i) the 4th meningeal membrane as claimed did not exist as a separate structure but was part of the arachnoid, (ii) the "outer SAS" compartment was likely an artifactual subdural space created by the experimental procedures, and (iii) the 4th membrane barrier property was confused with the arachnoid barrier. Subsequent publications in late 2023 indeed showed that Prox1 + cells are embedded within the arachnoid and located immediately inside of and firmly attached to the arachnoid barrier cells by adherens junctions and gap junctions. In a follow-up study, published in this journal, the lead authors of the Science paper Kjeld Møllgård and Maiken Nedergaard reported additional observations they claim support the existence of a 4th meningeal membrane and the compartmentalization of the SAS into two non-communicating spaces. Their minor modification to the original paper was the 4th meningeal membrane was better observable at the ventral side of the brain than at the dorsal side where it was originally reported. The authors also claimed support for the existence of a 4th meningeal membrane in classical literature. Here, we outline multiple concerns over the new data and interpretation and argue against the claim there is prior support in the literature for a 4th meningeal membrane.

Soluble CD26: From Suggested Biomarker for Cancer Diagnosis to Plausible Marker for Dynamic Monitoring of Immunotherapy

Soluble CD26 (sCD26), a glycoprotein with dipeptidyl peptidase (DPP4) enzymatic activity, can contribute to early diagnosis of colorectal cancer and advanced adenomas and has been studied, including for prognostic purposes, across various other types of cancer and disease. The latest research in this field has confirmed that most, though not all, serum/plasma sCD26 is related to inflammation. The shedding and/or secretion of sCD26 from different immune cells are being investigated, and blood DPP4 activity levels do not correlate very strongly with protein titers. Some of the main substrates of this enzyme are key chemokines involved in immune cell migration, and both soluble and cell-surface CD26 can bind adenosine deaminase (ADA), an enzyme involved in the metabolism of immunosuppressor extracellular adenosine. Of note, there are T cells enriched in CD26 expression and, in mice tumor models, tumor infiltrating lymphocytes exhibited heightened percentages of CD26+ correlating with tumor regression. We employed sCD26 as a biomarker in the follow-up after curative resection of colorectal cancer for the early detection of tumor recurrence. Changes after treatment with different biological disease-modifying antirheumatic drugs, including Ig-CTLA4, were also observed in rheumatoid arthritis. Serum soluble CD26/DPP4 titer variation has recently been proposed as a potential prognostic biomarker after a phase I trial in cancer immunotherapy with a humanized anti-CD26 antibody. We propose that dynamic monitoring of sCD26/DPP4 changes, in addition to well-known inflammatory biomarkers such as CRP already in use as informative for immune checkpoint immunotherapy, may indicate resistance or response during the successive steps of the treatment. As tumor cells expressing CD26 can also produce sCD26, the possibility of sorting immune- from non-immune-system-originated sCD26 is discussed.

Proliferating macrophages in human tumours show characteristics of monocytes responding to myelopoietic growth factors

Macrophages play essential roles in maintaining tissue homeostasis and immune defence. However, their extensive infiltration into tumours has been linked to adverse outcomes in multiple human cancers. Within the tumour microenvironment (TME), tumour-associated macrophages (TAMs) promote tumour growth and metastasis, making them prime targets for cancer immunotherapy. Recent single-cell analysis suggest that proliferating TAMs accumulate in human cancers, yet their origins and differentiation pathways remain uncertain. Here, we show that a subpopulation of CD163+ TAMs proliferates in situ within the TME of melanoma, lung cancer, and breast cancer. Consistent with their potential role in suppressing anti-tumour activities of T cells, CD163+ TAMs express a range of potent immunosuppressive molecules, including PD-L1, PD-L2, IL-10, and TGF-β. Other phenotypic markers strongly suggested that these cells originate from CD14+ CCR2+ monocytes, a cell population believed to have minimal capacity for proliferation. However, we demonstrate in vitro that certain myelopoietic cytokines commonly available within the TME induce robust proliferation of human monocytes, especially the combination of interleukin 3 (IL-3) and Macrophage Colony-Stimulating Factor 1 (M-CSF). Monocytic cells cultured with these cytokines efficiently modulate T cell proliferation, and their molecular phenotype recapitulates that of CD163+ TAMs. IL-3-driven proliferation of monocytic cells can be completely blocked by IL-4, associated with the induction of CDKN1A, alongside the upregulation of transcription factors linked to dendritic cell function, such as BATF3 and IRF4. Taken together, our work suggests several novel therapeutic routes to reducing immunosuppressive TAMs in human tumours, from blocking chemokine-mediated recruitment of monocytes to blocking their proliferation.

Adipokines in atopic dermatitis: the link between obesity and atopic dermatitis

Atopic dermatitis (AD) is a chronic skin condition with intense pruritus, eczema, and dry skin. The recurrent intense pruritus and numerous complications in patients with AD can profoundly affect their quality of life. Obesity is one of its comorbidities that has been confirmed to be the hazard factor of AD and also worsen its severity. Nevertheless, the specific mechanisms that explain the connection between obesity and AD remain incompletely recognized. Recent studies have built hopes on various adipokines to explain this connection. Adipokines, which are disturbed by an obese state, may lead to immune system imbalances in people with AD and promote the development of the disease. This review focuses on the abnormal expression patterns of adipokines in patients with AD and their potential regulatory molecular mechanisms associated with AD. The connection between AD and obesity is elucidated through the involvement of adipokines. This conduces to the in-depth exploration of AD pathogenesis and provides a new perspective to develop therapeutic targets.

DPP2/7 is a Potential Predictor of Prognosis and Target in Immunotherapy in Colorectal Cancer: An Integrative Multi-omics Analysis

BACKGROUND

Colorectal cancer (CRC) ranks among the leading causes of cancerrelated deaths.

OBJECTIVE

This study aimed to illuminate the relationship between DPP7 (also known as DPP2) and CRC through a combination of bioinformatics and experimental methodologies.

METHODS

A multi-dimensional bioinformatic analysis on DPP7 was executed, covering its expression, survival implications, clinical associations, functional roles, immune interactions, and drug sensitivities. Experimental validations involved siRNA-mediated DPP7 knockdown and various cellular assays.

RESULTS

Data from the Cancer Genome Atlas (TCGA) identified high DPP7 expression in solid CRC tumors, with elevated levels adversely affecting patient prognosis. A shift from the N0 to the N2 stage in CRC was associated with increased DPP7 expression. Functional insights indicated the involvement of DPP7 in cancer progression, particularly in extracellular matrix disassembly. Immunological analyses showed its association with immunosuppressive entities, and in vitro experiments in CRC cell lines underscored its oncogenic attributes.

CONCLUSION

DPP7 could serve as a CRC prognosis marker, functioning as an oncogene and representing a potential immunotherapeutic target.

Advances in Research on Type 2 Diabetes Mellitus Targets and Therapeutic Agents

Diabetes mellitus is a chronic multifaceted disease with multiple potential complications, the treatment of which can only delay and prolong the terminal stage of the disease, i.e., type 2 diabetes mellitus (T2DM). The World Health Organization predicts that diabetes will be the seventh leading cause of death by 2030. Although many antidiabetic medicines have been successfully developed in recent years, such as GLP-1 receptor agonists and SGLT-2 inhibitors, single-target drugs are gradually failing to meet the therapeutic requirements owing to the individual variability, diversity of pathogenesis, and organismal resistance. Therefore, there remains a need to investigate the pathogenesis of T2DM in more depth, identify multiple therapeutic targets, and provide improved glycemic control solutions. This review presents an overview of the mechanisms of action and the development of the latest therapeutic agents targeting T2DM in recent years. It also discusses emerging target-based therapies and new potential therapeutic targets that have emerged within the last three years. The aim of our review is to provide a theoretical basis for further advancement in targeted therapies for T2DM.

Efficacy of combination therapy with GABA, a DPP-4i and a PPI as an adjunct to insulin therapy in patients with type 1 diabetes

Introduction

The purpose of this retrospective clinic chart review study was to determine the potential of a combination therapy (CT) consisting of γ-aminobutyric acid (GABA), a dipeptidyl peptidase-4 inhibitor (DPP-4i), and a proton pump inhibitor (PPI) to improve glycemic control as an adjunct to insulin therapy in patients with type 1 diabetes (T1D).

Research design and methods

Nineteen patients with T1D on insulin therapy were treated with additional CT in oral form. Fasting blood glucose (FBG), HbA1c, insulin dose-adjusted HbA1c (IDA-A1c), daily insulin dose, insulin/weight ratio (IWR), and fasting plasma C-peptide were measured after 26-42 weeks of treatments.

Results

FBG, HbA1c, IDA-A1c, insulin dose and IWR were all significantly decreased while plasma C-peptide was significantly increased by the CT. Treatment outcomes were further analyzed by separation of the 19 patients into two groups. One group started on the CT within 12 months of insulin treatment (early therapy, 10 patients) and another group started on this therapy only after 12 months of insulin treatment (late therapy, 9 patients). FBG, IDA-A1c, insulin dose, and IWR decreased significantly in both the early and late CT groups, however to a better extent in the early therapy group. Moreover, plasma C-peptide increased significantly only in the early therapy group, and 7 of the 10 patients in this group were able to discontinue insulin treatment while maintaining good glycemic control to study end compared with none of the 9 patients in the late therapy group.

Conclusion

These results support the concept that the combination of GABA, a DPP-4i and a PPI as an adjunct to insulin therapy improves glycemic control in patients with T1D, and that the insulin dose required for glycemic control can be reduced or even eliminated in some patients receiving this novel therapy.

Systematic Review and Meta-Analyses of Aminopeptidases as Prognostic Biomarkers in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons in the spinal cord, brain stem, and cerebral cortex. Biomarkers for ALS are essential for disease detection and to provide information on potential therapeutic targets. Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or substrates such as neuropeptides. Since certain aminopeptidases are known to increase the risk of neurodegeneration, such mechanisms may reveal new targets to determine their association with ALS risk and their interest as a diagnostic biomarker. The authors performed a systematic review and meta-analyses of genome-wide association studies (GWASs) to identify reported aminopeptidases genetic loci associated with the risk of ALS. PubMed, Scopus, CINAHL, ISI Web of Science, ProQuest, LILACS, and Cochrane databases were searched to retrieve eligible studies in English or Spanish, published up to 27 January 2023. A total of 16 studies were included in this systematic review, where a series of aminopeptidases could be related to ALS and could be promising biomarkers (DPP1, DPP2, DPP4, LeuAP, pGluAP, and PSA/NPEPPS). The literature reported the association of single-nucleotide polymorphisms (SNPs: rs10260404 and rs17174381) with the risk of ALS. The genetic variation rs10260404 in the DPP6 gene was identified to be highly associated with ALS susceptibility, but meta-analyses of genotypes in five studies in a matched cohort of different ancestry (1873 cases and 1861 control subjects) showed no ALS risk association. Meta-analyses of eight studies for minor allele frequency (MAF) also found no ALS association for the "C" allele. The systematic review identified aminopeptidases as possible biomarkers. However, the meta-analyses for rs1060404 of DPP6 do not show a risk associated with ALS.

Autoimmunity and Immunodeficiency in Severe SARS-CoV-2 Infection and Prolonged COVID-19

SARS-CoV-2 causes the complex and heterogeneous illness known as COVID-19. The disease primarily affects the respiratory system but can quickly become systemic, harming multiple organs and leading to long-lasting sequelae in some patients. Most infected individuals are asymptomatic or present mild symptoms. Antibodies, complement, and immune cells can efficiently eliminate the virus. However, 20% of individuals develop severe respiratory illness and multiple organ failure. Virus replication has been described in several organs in patients who died from COVID-19, suggesting a compromised immune response. Immunodeficiency and autoimmunity are responsible for this impairment and facilitate viral escape. Mutations in IFN signal transduction and T cell activation are responsible for the inadequate response in young individuals. Autoantibodies are accountable for secondary immunodeficiency in patients with severe infection or prolonged COVID-19. Antibodies against cytokines (interferons α, γ and ω, IL1β, IL6, IL10, IL-17, IL21), chemokines, complement, nuclear proteins and DNA, anticardiolipin, and several extracellular proteins have been reported. The type and titer of autoantibodies depend on age and gender. Organ-specific autoantibodies have been described in prolonged COVID-19. Their role in the disease is under study. Autoimmunity and immunodeficiency should be screened as risk factors for severe or prolonged COVID-19.

Targeting Immune Senescence in Atherosclerosis

Atherosclerosis is one of the main underlying causes of cardiovascular diseases (CVD). It is associated with chronic inflammation and intimal thickening as well as the involvement of multiple cell types including immune cells. The engagement of innate or adaptive immune response has either athero-protective or atherogenic properties in exacerbating or alleviating atherosclerosis. In atherosclerosis, the mechanism of action of immune cells, particularly monocytes, macrophages, dendritic cells, and B- and T-lymphocytes have been discussed. Immuno-senescence is associated with aging, viral infections, genetic predispositions, and hyperlipidemia, which contribute to atherosclerosis. Immune senescent cells secrete SASP that delays or accelerates atherosclerosis plaque growth and associated pathologies such as aneurysms and coronary artery disease. Senescent cells undergo cell cycle arrest, morphological changes, and phenotypic changes in terms of their abundances and secretome profile including cytokines, chemokines, matrix metalloproteases (MMPs) and Toll-like receptors (TLRs) expressions. The senescence markers are used in therapeutics and currently, senolytics represent one of the emerging treatments where specific targets and clearance of senescent cells are being considered as therapy targets for the prevention or treatment of atherosclerosis.

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.

Dipeptidyl Peptidase 4 (DPP4) as A Novel Adipokine: Role in Metabolism and Fat Homeostasis

Dipeptidyl peptidase 4 (DPP4) is a molecule implicated in the regulation of metabolic homeostasis and inflammatory processes, and it exerts its main action through its enzymatic activity. DPP4 represents the enzyme most involved in the catabolism of incretin hormones; thus, its activity impacts appetite, energy balance, and the fine regulation of glucose homeostasis. Indeed, DPP4 inhibitors represent a class of antidiabetic agents widely used for the treatment of Type 2 diabetes mellitus (T2DM). DPP4 also acts as an adipokine and is mainly secreted by the adipose tissue, mostly from mature adipocytes of the visceral compartment, where it exerts autocrine and paracrine activities. DPP4 can disrupt insulin signaling within the adipocyte and in other target cells and tissues, where it also favors the development of a proinflammatory environment. This is likely at the basis of the presence of elevated circulating DPP4 levels in several metabolic diseases. In this review, we summarize the most recent evidence of the role of the DPP4 as an adipokine-regulating glucose/insulin metabolism and fat homeostasis, with a particular focus on clinical outcomes associated with its increased secretion in the presence of adipose tissue accumulation and dysfunction.

Role of Dipeptidyl Peptidase-4 (DPP4) on COVID-19 Physiopathology

DPP4/CD26 is a single-pass transmembrane protein with multiple functions on glycemic control, cell migration and proliferation, and the immune system, among others. It has recently acquired an especial relevance due to the possibility to act as a receptor or co-receptor for SARS-CoV-2, as it has been already demonstrated for other coronaviruses. In this review, we analyze the evidence for the role of DPP4 on COVID-19 risk and clinical outcome, and its contribution to COVID-19 physiopathology. Due to the pathogenetic links between COVID-19 and diabetes mellitus and the hyperinflammatory response, with the hallmark cytokine storm developed very often during the disease, we dive deep into the functions of DPP4 on carbohydrate metabolism and immune system regulation. We show that the broad spectrum of functions regulated by DPP4 is performed both as a protease enzyme, as well as an interacting partner of other molecules on the cell surface. In addition, we provide an update of the DPP4 inhibitors approved by the EMA and/or the FDA, together with the newfangled approval of generic drugs (in 2021 and 2022). This review will also cover the effects of DPP4 inhibitors (i.e., gliptins) on the progression of SARS-CoV-2 infection, showing the role of DPP4 in this disturbing disease.

Glucose as a Potential Key to Fuel Inflammation in Rheumatoid Arthritis

Glucose is the most important source of energy and homeostasis. Recent investigations are clarifying that glucose metabolism might be altered in rheumatoid arthritis (RA), which would play a role in the inflammatory phenotype of rheumatoid synovial fibroblasts. It may also play a role in a variety of autoimmune diseases’ pathophysiology by modulating immune responses and modifying autoantigen expressions. The research into glucose and its metabolism could lead to a better understanding of how carbohydrates contribute to the occurrence and duration of RA and other autoimmune diseases.