Sitagliptin Reduces Inflammation and Chronic Immune Cell Activation in HIV+ Adults With Impaired Glucose Tolerance

Treatment with sitagliptin exacerbates the M2 phenotype in macrophages in vitro

Macrophages (MØ) participate in the induction and the control of the host's immune response in homeostasis and during inflammatory diseases. Sitagliptin is a drug that inhibits the enzyme dipeptidyl peptidase 4 (DPP-4) and, therefore, increases the bioavailability of the incretins GIP (Gastric inhibitory polypeptide) and GLP-1 (Glucagon-like polypeptide). Thus, sitagliptin has been used to treat obesity and type II diabetes and has recently been associated with anti-inflammatory effects. It is known that the drug can modulate the immune response, however, the underlying mechanisms are not yet completely elucidated, including how they interfere with the activation and function of MØ. Here, we aimed to investigate and characterize the effects of in vitro treatment with sitagliptin on MØ polarization. Bone marrow-derived MØ were differentiated with conditioned medium from the L929 cell line. For M1, MØ were stimulated with IFN-γ and LPS, and for M2, with IL-4 and IL-13 for 24 h. Sitagliptin treatment was performed during MØ polarization. Polarized MØ were assessed for M1/M2 markers, DPP-4, GLP-1 and GIP receptors, mitochondrial dynamics and phagocytosis. Sitagliptin treatment exacerbates the M2 phenotype, featured by increased expression of CD206 and ARG1 and decreased gene expression levels of TNF-α. Sitagliptin-treated M2 altered mitochondrial dynamics with reduced membrane potential and mitochondrial reactive oxygen species production. These differences were accompanied by low gene expression levels of genes related to mitofusion, suggesting that sitagliptin treatment interferes with mitochondria function in M2, and exhibited less phagocytic capacity. In summary, our data suggest that sitagliptin exacerbates M2 profile in vitro.

Chronic immune activation and accelerated immune aging among HIV-infected adults receiving suppressive antiretroviral therapy for at least 12 years in an African cohort

Background

HIV-associated alterations innate and adaptive immune cell compartments are reminiscent of the process of immune aging.

Objectives

We described immune aging phenotypes among ART-treated HIV-infected adults relative to age-matched HIV-negative counterparts.

Methods

In a cross-sectional comparative study of HIV-infected adults with CD4≥500 cells/μl after at least 12 years of suppressive ART and age-and-gender-matched HIV-negative individuals, immune activation and immune aging phenotypes were measured, using multi-color flowcytometry.

Results

ART-treated HIV-infected individuals had higher body mass index (P = 0.004), waist-hip circumference (P = 0.041), hip circumference (P < 0.001), and diastolic blood pressure (P = 0.012) and immune activation (CD4+CD38+HLADR+; median 4.15,IQR(1.030,14.6)] relative to the HIV-negative age-matched individuals [median 3.14,IQR(1.030, 6.68)]; P=0.0034. Immune aging markers [CD4+CD57+T-cells; median 13.00 IQR (0.45,64.1)] were higher among HIV-infected ART-treated adults<50 years relative to HIV-negative<50 years[median 8.020,IQR(0.004,21.2)]; P=0.0010. Naïve CD4 T-cells, Central memory CD4 T-cells, Terminal Effector Memory T cells (TEMRA: CD27-CD45RA + CCR7-) and immune senescence CD4/CD8+CD28-/CD57+ T-cells were similar among ART-treated HIV-infected individuals<45 years relative to 60 years-and-older HIV-negative counterparts≥; p = 0.0932, p = 0.05357, p = 0.0950 and p = 0.5714 respectively.

Conclusion

ART-treated adults are immunologically two decades older than their HIV-negative counterparts. Accelerated immune aging among individuals aging with HIV underscores the need for an HIV cure to avert the unprecedented complications of accelerated immune senescence and the associated NCD risk in African settings with protracted exposure to endemic co-infections.

Pharmacological and Behavioral Interventions to Mitigate Premature Aging in Patients with HIV

PURPOSE OF REVIEW

We sought to review pharmacological and behavioral interventions that have been publicly presented, published, or are currently ongoing to prevent or mitigate the effect of premature HIV-associated comorbidities.

RECENT FINDINGS

Multiple studies have been conducted in hopes of finding an effective intervention. While the choice of antiretroviral regimen influences recovery of immune function, several drugs used as adjunct treatments have proven effective to mitigate premature aging. Additionally, few behavioral interventions have exhibited some efficacy. Statins, angiotensin-receptor blockers, and anti-hyperglycemic agents as well as optimal adherence, exercise, and intermittent fasting among others have had beneficial impact on markers of immune activation and levels of inflammatory biomarkers. However, several investigations had inconclusive outcomes so further studies with larger sample sizes are warranted.

Identification of drug candidates targeting monocyte reprogramming in people living with HIV

Introduction

People living with HIV (PLHIV) are characterized by functional reprogramming of innate immune cells even after long-term antiretroviral therapy (ART). In order to assess technical feasibility of omics technologies for application to larger cohorts, we compared multiple omics data layers.

Methods

Bulk and single-cell transcriptomics, flow cytometry, proteomics, chromatin landscape analysis by ATAC-seq as well as ex vivo drug stimulation were performed in a small number of blood samples derived from PLHIV and healthy controls from the 200-HIV cohort study.

Results

Single-cell RNA-seq analysis revealed that most immune cells in peripheral blood of PLHIV are altered in their transcriptomes and that a specific functional monocyte state previously described in acute HIV infection is still existing in PLHIV while other monocyte cell states are only occurring acute infection. Further, a reverse transcriptome approach on a rather small number of PLHIV was sufficient to identify drug candidates for reversing the transcriptional phenotype of monocytes in PLHIV.

Discussion

These scientific findings and technological advancements for clinical application of single-cell transcriptomics form the basis for the larger 2000-HIV multicenter cohort study on PLHIV, for which a combination of bulk and single-cell transcriptomics will be included as the leading technology to determine disease endotypes in PLHIV and to predict disease trajectories and outcomes.

The Many Faces of Immune Activation in HIV-1 Infection: A Multifactorial Interconnection

Chronic immune activation has a significant role in HIV-1 disease pathogenesis and CD4+ T-cell depletion. The causes of chronic inflammation and immune activation are incompletely understood, but they are likely multifactorial in nature, involving both direct and indirect stimuli. Possible explanations include microbial translocation, coinfection, and continued presence of competent replicating virus. In fact, long-term viral suppression treatments are unable to normalize elevated markers of systemic immune activation. Furthermore, high levels of pro-inflammatory cytokines increase susceptibility to premature aging of the immune system. The phenomenon of "inflammaging" has begun to be evident in the last decades, as a consequence of increased life expectancy due to the introduction of cART. Quality of life and survival have improved substantially; however, PLWH are predisposed to chronic inflammatory conditions leading to age-associated diseases, such as inflammatory bowel disease, neurocognitive disorders, cardiovascular diseases, metabolic syndrome, bone abnormalities, and non-HIV-associated cancers. Several approaches have been studied in numerous uncontrolled and/or randomized clinical trials with the aim of reducing immune activation/inflammatory status in PLWH, none of which have achieved consistent results.

Dipeptidyl peptidase IV inhibition delays developmental programming of obesity and metabolic disease in male offspring of obese mothers

Maternal obesity programs the offspring to metabolic diseases later in life; however, the mechanisms of programming are yet unclear, and no strategies exist for addressing its detrimental transgenerational effects. Obesity has been linked to dipeptidyl peptidase IV (DPPIV), an adipokine, and treatment of obese individuals with DPPIV inhibitors has been reported to prevent weight gain and improve metabolism. We hypothesized that DPPIV plays a role in maternal obesity-mediated programming. We measured plasma DPPIV activity in human maternal and cord blood samples from normal-weight and obese mothers at term. We found that maternal obesity increases maternal and cord blood plasma DPPIV activity but only in male offspring. Using two non-human primate models of maternal obesity, we confirmed the activation of DPPIV in the offspring of obese mothers. We then created a mouse model of maternal high-fat diet (HFD)-induced obesity, and found an early-life increase in plasma DPPIV activity in male offspring. Activation of DPPIV preceded the progression of obesity, glucose intolerance and insulin resistance in male offspring of HFD-fed mothers. We then administered sitagliptin, DPPIV inhibitor, to regular diet (RD)- and HFD-fed mothers, starting a week prior to breeding and continuing throughout pregnancy and lactation. We found that sitagliptin treatment of HFD-fed mothers delayed the progression of obesity and metabolic diseases in male offspring and had no effects on females. Our findings reveal that maternal obesity dysregulates plasma DPPIV activity in males and provide evidence that maternal inhibition of DPPIV has potential for addressing the transgenerational effects of maternal obesity.

Evaluation of the anti-diabetic drug sitagliptin as a novel attenuate to SARS-CoV-2 evidence-based in silico: molecular docking and molecular dynamics

The current outbreak of COVID-19 cases worldwide has been responsible for a significant number of deaths, especially in hospitalized patients suffering from comorbidities, such as obesity, diabetes, hypertension. The disease not only has prompted an interest in the pathophysiology, but also it has propelled a massive race to find new anti-SARS-CoV-2 drugs. In this scenario, known drugs commonly used to treat other diseases have been suggested as alternative or complementary therapeutics. Herein we propose the use of sitagliptin, an inhibitor of dipeptidyl peptidase-4 (DPP₄) used to treat type-II diabetes, as an agent to block and inhibit the activity of two proteases, 3CL^pro and PL^pro, related to the processing of SARS-CoV-2 structural proteins. Inhibition of these proteases may possibly reduce the viral load and infection on the host by hampering the synthesis of new viruses, thus promoting a better outcome. In silico assays consisting in the modeling of the ligand sitagliptin and evaluation of its capacity to interact with 3CL^pro and PL^pro through the prediction of the ligand bioactivity, molecular docking, overlapping of crystal structures, and molecular dynamic simulations were conducted. The experiments indicate that sitagliptin can interact and bind to both targets. However, this interaction seems to be stronger and more stable to 3CL^pro (ΔG = −7.8 kcal mol⁻¹), when compared to PL^pro (ΔG = −7.5 kcal mol⁻¹). This study suggests that sitagliptin may be suitable to treat COVID-19 patients, beyond its common use as an anti-diabetic medication. In vivo studies may further support this hypothesis.

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.

Mechanisms of immune aging in HIV

Massive CD4+ T-cell depletion as well as sustained immune activation and inflammation are hallmarks of Human Immunodeficiency Virus (HIV)-1 infection. In recent years, an emerging concept draws an intriguing parallel between HIV-1 infection and aging. Indeed, many of the alterations that affect innate and adaptive immune subsets in HIV-infected individuals are reminiscent of the process of immune aging, characteristic of old age. These changes, of which the presumed cause is the systemic immune activation established in patients, likely participate in the immuno-incompetence described with HIV progression. With the success of antiretroviral therapy (ART), HIV-seropositive patients can now live for many years despite chronic viral infection. However, acquired immunodeficiency syndrome (AIDS)-related opportunistic infections have given way to chronic diseases as the leading cause of death since HIV infection. Therefore, the comparison between HIV-1 infected patients and uninfected elderly individuals goes beyond the sole onset of immunosenescence and extends to the deterioration of several physiological functions related to inflammation and systemic aging. In light of this observation, it is interesting to understand the precise link between immune activation and aging in HIV-1 infection to figure out how to best care for people living with HIV (PLWH).

HIV-Related Immune Activation and Inflammation: Current Understanding and Strategies

Although antiretroviral therapy effectively controls human immunodeficiency virus (HIV) replication, a residual chronic immune activation/inflammation persists throughout the disease. This aberrant immune activation and inflammation are considered an accelerator of non-AIDS-related events and one of the driving forces of CD4⁺ T cell depletion. Unfortunately, HIV-associated immune activation is driven by various factors, while the mechanism of excessive inflammation has not been formally clarified. To date, several clinical interventions or treatment candidates undergoing clinical trials have been proposed to combat this systemic immune activation/inflammation. However, these strategies revealed limited results, or their nonspecific anti-inflammatory properties are similar to previous interventions. Here, we reviewed recent learnings of immune activation and persisting inflammation associated with HIV infection, as well as the current directions to overcome it. Of note, a more profound understanding of the specific mechanisms for aberrant inflammation is still imperative for identifying an effective clinical intervention strategy.

Cardiac adiposity as a modulator of cardiovascular disease in HIV

BACKGROUND

With the number of people living with human immunodeficiency virus (HIV) steadily increasing, cardiovascular disease has emerged as a leading cause of non-HIV related mortality. People living with HIV (PLWH) appear to be at increased risk of coronary artery disease and heart failure (HF), while the underlying mechanism appears to be multifactorial. In the general population, ectopic cardiac adiposity has been highlighted as an important modulator of accelerated coronary artery atherosclerosis, arrhythmogenesis and HF with preserved ejection fraction (HFpEF). Cardiac adiposity is also strongly linked with obesity, especially with visceral adipose tissue accumulation.

AIMS

This review aims to summarize the possible role of cardiac fat depositions, assessed by imaging modalities,as potential contributors to the increased cardiac morbidity and mortality seen in PLWH, as well as therapeutic targets in the current ART era.

MATERIALS & METHODS

Review of contemporary literature on this topic.

DISCUSSION

Despite antiretroviral therapy (ART), PLWH have evidence of persistent, HIV-related systemic inflammation and body fat alterations. Cardiac adiposity can play an additional role in the pathogenesis of cardiovascular disease in the HIV setting. Imaging modalities such as echocardiography, cardiac multidetector computed tomography and cardiac magnetic resonance have demonstrated increased adipose tissue. Studies show that high cardiac fat depots play an additive role in promoting coronary artery atherosclerosis and HFpEF in PLWH. Systemic inflammation due to HIV infection, metabolic adverse effects of ART, adipose alterations in the ageing HIV population, inflammation and immune activation are likely important mechanisms for adipose dysfunction and disproportionately occurrence of ectopic fat depots in the heart among PLWH.

CONCLUSIONS

High cardiac adiposity seems to plays an additive role in promoting coronary artery atherosclerosis and HFpEF in PLWH. The underlying mechanisms are multiple and warrant further investigation. Improved understanding of the regulating mechanisms that increase cardiovascular risk in HIV infection may give rise to more tailored therapeutic strategies targeting cardiac fat depots.

Adjunct Therapy for CD4+ T-Cell Recovery, Inflammation and Immune Activation in People Living With HIV: A Systematic Review and Meta-Analysis

Background: HIV infection results in immune homeostasis perturbations, which is characterized by CD4⁺ T-cell depletion, immune activation, and inflammation. Effective antiretroviral therapy (ART) does not fully restore immunologic and clinical health in people living with HIV (PLWH). Various drugs have been used to improve their immune status and CD4⁺ T-cell counts, but no measures have been tested effective. Here we conduct a systematic review and meta-analysis of existing clinical studies on improving CD4⁺ T-cell count while decreasing inflammation and immune activation.

Methods: We retrieved possible relevant publications from a total of five electronic databases and selected eligible studies, which dealt with outcomes of medical therapy for CD4⁺ T-cell count recovery, inflammation, and immune activation with or without ART. We paid particular attention to immunologic non-responders with a favorable treatment regimen.

Results: Thirty-three articles were included in the systematic review and meta-analysis. However, there were no safe and effective medications specific for improving CD4⁺ T-cell reconstitution. The immunological benefits or adverse events mainly depend on the safety, dosage, and duration of the candidate medication use, as well as whether it is combined with ART.

Conclusion: Under the “safe, combined, adequate and long (SCAL)” principles, alternative approaches are needed to accelerate the recovery of CD4⁺ T-cells, and to prevent adverse long-term outcomes in PLWH with standard ART treatment.

Infectious complications of newer agents in the fight against diabetes

Infectious complications have been reported with antidiabetic medications. Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors have been associated with upper respiratory tract infections and urinary tract infections. Sodium-glucose cotransporter 2 inhibitors have been associated with lower limb amputations, urinary tract infections, genital mycotic infections, and Fournier gangrene.

A Randomized, Double-blinded, Placebo-controlled Trial of Sitagliptin for Reducing Inflammation and Immune Activation in Treated and Suppressed Human Immunodeficiency Virus Infection

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitors have pleotropic anti-inflammatory and immune regulatory effects in addition to glucoregulation. We evaluated inflammation and immune markers in suppressed human immunodeficiency virus (HIV) infection during treatment with the DPP-4 inhibitor sitagliptin.

METHODS

Virologically suppressed adults with HIV without diabetes on stable antiretroviral therapy (ART) with ≥100/μL CD4 cells were randomized to 16 weeks of sitagliptin 100 mg/day vs placebo in a multicenter trial. The primary endpoint was the change in plasma soluble CD14 (sCD14) from baseline to week 15-16.

RESULTS

Ninety participants were randomized, and 42 from each arm were included in per-protocol analyses. Participants were 45% non-Hispanic white, 38% non-Hispanic black, and 15% Hispanic, with a median age of 51 years; 83% were male; and the median CD4 count was 602 cells/μL. At week 15-16, there was no difference in sCD14 change between the 2 arms (P = .69). Relative to placebo, the sitagliptin arm had 47% greater decline in CXCL10 (95% confidence interval, -57% to -35%) at week 15 (P < .001). There were no significant between-arm differences in other soluble biomarkers, total CD4 and CD8 counts, or markers of lymphocyte or monocyte activation. Sitagliptin was well tolerated.

CONCLUSIONS

Sixteen weeks of sitagliptin had no effect on sCD14 levels in virologically suppressed participants with HIV. CXCL10, a chemokine involved in atherogenesis that predicts non-AIDS events during ART, declined markedly with sitagliptin. This suggests that DPP-4 inhibition has the potential to reduce cardiovascular morbidity in treated HIV infection.

CLINICAL TRIALS REGISTRATION

NCT01426438.

Feasibility of quantifying change in immune white cells in abdominal adipose tissue in response to an immune modulator in clinical obesity

BACKGROUND

Obesity is often associated with inflammation in adipose tissue (AT) with release of mediators of atherogenesis. We postulated that it would be feasible to collect sufficient abdominal AT to quantify changes in a broad array of adaptive and innate mononuclear white cells in obese non-diabetic adults in response to a dipeptidyl protease inhibitor (DPP4i), known to inhibit activation of immune white cells.

METHODS

Adults 18-55 years-of-age were screened for abdominal obesity and insulin resistance or impaired glucose tolerance but without known inflammatory conditions. Twenty-one eligible participants consented for study and were randomized 3:1 to receive sitagliptin (DPP4i) at 100mg or matching placebo daily for 28 days. Abdominal AT collected by percutaneous biopsy and peripheral blood mononuclear cell fractions were evaluated before and after treatment; plasma was stored for batch testing.

RESULTS

Highly sensitive C-reactive protein, a global marker of inflammation, was not elevated in the study population. Innate lymphoid cells (ILC) type 3 (ILC-3) in abdominal AT decreased with active treatment compared with placebo (p = 0.04). Other immune white cells in AT and peripheral blood mononuclear cell (PBMC) fractions did not change with treatment compared to placebo (p>0.05); although ILC-2 declined in PBMCs (p = 0.007) in the sitagliptin treatment group. Two circulating biomarkers of atherogenesis, interferon-inducible protein-10 (IP-10) and sCD40L declined in plasma (p = 0.02 and p = 0.07, respectively) in the active treatment group, providing indirect validation of a net reduction in inflammation.

CONCLUSIONS

In this pilot study, two cell types of the innate lymphoid system, ILC-3 in AT and ILC-2 PBMCs declined during treatment and as did circulating biomarkers of atherogenesis. Changes in other immune cells were not demonstrable. The study showed that sufficient abdominal AT could be obtained to quantify white cells of both innate and adaptive immunity and to demonstrate changes during therapy with an immune inhibitor.

TRIAL REGISTRATION

ClinicalTrials.gov identifier (NCT number): NCT02576.

Coronavirus Infections and Type 2 Diabetes-Shared Pathways with Therapeutic Implications

Individuals with diabetes are at increased risk for bacterial, mycotic, parasitic, and viral infections. The severe acute respiratory syndrome (SARS)-CoV-2 (also referred to as COVID-19) coronavirus pandemic highlights the importance of understanding shared disease pathophysiology potentially informing therapeutic choices in individuals with type 2 diabetes (T2D). Two coronavirus receptor proteins, angiotensin-converting enzyme 2 (ACE2) and dipeptidyl peptidase-4 (DPP4) are also established transducers of metabolic signals and pathways regulating inflammation, renal and cardiovascular physiology, and glucose homeostasis. Moreover, glucose-lowering agents such as the DPP4 inhibitors, widely used in subjects with T2D, are known to modify the biological activities of multiple immunomodulatory substrates. Here, we review the basic and clinical science spanning the intersections of diabetes, coronavirus infections, ACE2, and DPP4 biology, highlighting clinical relevance and evolving areas of uncertainty underlying the pathophysiology and treatment of T2D in the context of coronavirus infection.

Effects of saxagliptin on adipose tissue inflammation and vascular function in overweight and obese people: a placebo-controlled study

AIMS

To test the effect of the dipeptidyl peptidase-4 inhibitor saxagliptin on adipose tissue inflammation and microvascular function, and whole-body postprandial endothelial function.

METHODS

A randomized, double-blind, placebo-controlled, parallel study was conducted between June 2013 and November 2016 in 44 overweight or obese people without diabetes (saxagliptin, n=28; placebo, n=16). Subcutaneous abdominal adipose tissue biopsies, a 4-h fat-enriched meal test and peripheral arterial tonometry for measurement of endothelial function were performed at baseline and after 6 weeks of treatment with saxagliptin (5 mg/day) or matching placebo.

RESULTS

Forty participants were analysed (saxagliptin, n=26; placebo, n=14). Secretion of interleukin-8 from adipose tissue explants was reduced after saxagliptin (median fold-change from baseline: 0.8 saxagliptin vs 3.3 placebo; P=0.02). Adipose tissue expression of thioredoxin-inhibitory protein (TxNIP) was lower after saxagliptin (0.75 vs 1.0; P=0.02), while there were no significant differences in adipose tissue secretion of interleukin-1b, interleukin-6 or macrophage chemoattractant protein 1 (MCP-1), adipose tissue macrophage content, adipose tissue mRNA levels of mcp1, cd36, cd68, il6, il8, txnip and adpq, and activation of adipose tissue inflammatory pathways [extracellular signal-regulated kinase, c-Jun N-terminal kinase (JNK) and nuclear factor-κB (NF- κB)] or insulin-induced vasodilation of adipose tissue arterioles. Postprandial plasma glucose was slightly lower (by an estimated 0.3 mmol/l; P=0.01), while postprandial insulin, triglyceride levels and endothelial function were unchanged after saxagliptin.

CONCLUSIONS

The effect of saxagliptin on adipose tissue inflammation was relatively modest, with many inflammatory markers unchanged. We also found no evidence that saxagliptin therapy improved adipose tissue arteriole vasodilation or postprandial endothelial function.

Obesity and Fat Metabolism in Human Immunodeficiency Virus-Infected Individuals: Immunopathogenic Mechanisms and Clinical Implications

Metabolic complications relating to complex effects of viral and immune-mediated mechanisms are now a focus of clinical care among persons living with human immunodeficiency virus (PLHIV), and obesity is emerging as a critical problem. To address knowledge gaps, the US National Institutes of Health sponsored a symposium in May 2018 entitled "Obesity and Fat Metabolism in HIV-infected Individuals." Mechanisms relating to adipose dysfunction and fibrosis, immune function, inflammation, and gastrointestinal integrity were highlighted as contributors to obesity among PLHIV. Fibrotic subcutaneous adipose tissue is metabolically dysfunctional and loses its capacity to expand, leading to fat redistribution, including visceral obesity and ectopic fat accumulation, promoting insulin resistance. Viral proteins, including viral protein R and negative regulatory factor, have effects on adipogenic pathways and cellular metabolism in resident macrophages and T cells. HIV also affects immune cell trafficking into the adipose compartments, with effects on adipogenesis, lipolysis, and ectopic fat accumulation. Key cellular metabolic functions are likely to be affected in PLHIV by gut-derived cytokines and altered microbiota. There are limited strategies to reduce obesity specifically in PLHIV. Enhancing our understanding of critical pathogenic mechanisms will enable the development of novel therapeutics that may normalize adipose tissue function and distribution, reduce inflammation, and improve insulin sensitivity in PLHIV.

Pharmacology of dipeptidyl peptidase-4 inhibitors and its use in the management of metabolic syndrome: a comprehensive review on drug repositioning

OBJECTIVES

Despite advances in our understanding of metabolic syndrome (MetS) and the treatment of each of its components separately, currently there is no single therapy approved to manage it as a single condition. Since multi-drug treatment increases drug interactions, decreases patient compliance and increases health costs, it is important to introduce single therapies that improve all of the MetS components.

EVIDENCE ACQUISITION

We conducted a PubMed, Scopus, Google Scholar, Web of Science, US FDA, utdo.ir and clinicaltrial.gov search, gathered the most relevant preclinical and clinical studies that have been published since 2010, and discussed the beneficial effects of dipeptidyl peptidase (DPP)-4 inhibitors to prevent and treat different constituent of the MetS as a single therapy. Furthermore, the pharmacology of DPP-4 inhibitors, focusing on pharmacodynamics, pharmacokinetics, drug interactions and their side effects are also reviewed.

RESULTS

DPP-4 inhibitors or gliptins are a new class of oral anti-diabetic drugs that seem safe drugs with no severe side effects, commonly GI disturbance, infection and inflammatory bowel disease. They increase mass and function of pancreatic β-cells, and insulin sensitivity in liver, muscle and adipose tissue. It has been noted that gliptin therapy decreases dyslipidemia. DPP-4 inhibitors increase fatty oxidation, and cholesterol efflux, and decrease hepatic triglyceride synthase and de novo lipogenesis. They delay gastric emptying time and lead to satiety. Besides, gliptin therapy has anti-inflammatory and anti-atherogenic impacts, and improves endothelial function and reduces vascular stiffness.

CONCLUSION

The gathered data prove the efficacy of DPP-4 inhibitors in managing MetS in some levels beyond anti-diabetic effects. This review could be a lead for designing new DPP-4 inhibitors with greatest effects on MetS in future. Introducing drugs with polypharmacologic effects could increase the patient's compliance and decrease the health cost that there is not in multi-drug therapy. Graphical abstract ᅟ.

Inhibition of DPP4 enhances inhibitory synaptic transmission through activating the GLP-1/GLP-1R signaling pathway in a rat model of febrile seizures

Dipeptidyl peptidase-IV (DPP4) is a cell surface serine peptidase widely expressed in the brain. Recent studies suggest that DPP4 contributes to the development of febrile seizures (FS); however, the underlying mechanism is still unclear. Thus, we investigated the role of DPP4 in the progression of FS at the molecular and electrophysiological levels using FS models in vivo and in vitro. Herein, we found that both the mRNA and protein levels of DPP4 were upregulated in the FS model. Administration of the pharmacological DPP4 inhibitor sitagliptin suppressed the hyperthermia-induced neuronal excitability as determined via whole-cell patch-clamp recordings in vitro. Interestingly, sitagliptin administration activated the glucagon-like peptide-1 (GLP-1)/GLP-1 receptor (GLP-1R) pathway by increasing the expression of GLP-1 and GLP-1R in a rat model of FS. Moreover, administration of the GLP-1R inhibitor exendin9-39 increased seizure severity, and sitagliptin reversed the effect, as shown in the electroencephalogram (EEG) and patch-clamp results in a rat model of FS. Furthermore, the GLP-1R-mediated reduction in GABAergic transmission was enhanced by sitagliptin and DPP4 knockdown through increasing miniature inhibitory post-synaptic currents (mIPSCs) in vitro accompanied by increased synaptic release of GABA in vivo. Taken together, our results demonstrate a role of DPP4 in regulating GABAergic transmission via the GLP-1/GLP-1R pathway. These findings indicated that DPP4 may represent a novel therapeutic strategy and target for FS.

Impact of dipeptidyl-peptidase 4 inhibitors on cardiovascular diseases

Dipeptidyl peptidase 4 (DPP-4) inhibitor is a novel group of medicine employed in type 2 diabetes mellitus (T2DM),which improves meal stimulated insulin secretion by protecting glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) from enzymatic degradation. Cardiovascular diseases are serious complications and leading causes of mortality among individuals with diabetes mellitus. Glycemic control per se seems to fail in preventing the progression of diabetic cardiovascular complications. DPP-4 has the capability to inactivate not only incretins, but also a series of cytokines, chemokines, and neuropeptides involved in inflammation, immunity, and vascular function. Pre-clinical studies suggested that DPP-4 inhibitors may have potential cardiovascular protective effects in addition to their antidiabetic actions. In recent years, a number of clinical trials have been conducted to evaluate the effect of different DPP-4 inhibitors on the cardiovascular system. We herein review the available clinical studies in cardiovascular effects played by each DPP-4 inhibitor and discuss the prospective application of DPP-4 inhibitors on cardiovascular diseases.

Dipeptidyl-peptidase (DPP)-4 inhibitors and glucagon-like peptide (GLP)-1 analogues for prevention or delay of type 2 diabetes mellitus and its associated complications in people at increased risk for the development of type 2 diabetes mellitus

BACKGROUND

The projected rise in the incidence of type 2 diabetes mellitus (T2DM) could develop into a substantial health problem worldwide. Whether dipeptidyl-peptidase (DPP)-4 inhibitors or glucagon-like peptide (GLP)-1 analogues are able to prevent or delay T2DM and its associated complications in people at risk for the development of T2DM is unknown.

OBJECTIVES

To assess the effects of DPP-4 inhibitors and GLP-1 analogues on the prevention or delay of T2DM and its associated complications in people with impaired glucose tolerance, impaired fasting blood glucose, moderately elevated glycosylated haemoglobin A1c (HbA1c) or any combination of these.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials; MEDLINE; PubMed; Embase; ClinicalTrials.gov; the World Health Organization (WHO) International Clinical Trials Registry Platform; and the reference lists of systematic reviews, articles and health technology assessment reports. We asked investigators of the included trials for information about additional trials. The date of the last search of all databases was January 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with a duration of 12 weeks or more comparing DPP-4 inhibitors and GLP-1 analogues with any pharmacological glucose-lowering intervention, behaviour-changing intervention, placebo or no intervention in people with impaired fasting glucose, impaired glucose tolerance, moderately elevated HbA1c or combinations of these.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles and records, assessed quality and extracted outcome data independently. One review author extracted data which were checked by a second review author. We resolved discrepancies by consensus or the involvement of a third review author. For meta-analyses, we planned to use a random-effects model with investigation of risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the overall quality of the evidence using the GRADE instrument.

MAIN RESULTS

We included seven completed RCTs; about 98 participants were randomised to a DPP-4 inhibitor as monotherapy and 1620 participants were randomised to a GLP-1 analogue as monotherapy. Two trials investigated a DPP-4 inhibitor and five trials investigated a GLP-1 analogue. A total of 924 participants with data on allocation to control groups were randomised to a comparator group; 889 participants were randomised to placebo and 33 participants to metformin monotherapy. One RCT of liraglutide contributed 85% of all participants. The duration of the intervention varied from 12 weeks to 160 weeks. We judged none of the included trials at low risk of bias for all 'Risk of bias' domains and did not perform meta-analyses because there were not enough trials.One trial comparing the DPP-4 inhibitor vildagliptin with placebo reported no deaths (very low-quality evidence). The incidence of T2DM by means of WHO diagnostic criteria in this trial was 3/90 participants randomised to vildagliptin versus 1/89 participants randomised to placebo (very low-quality evidence). Also, 1/90 participants on vildagliptin versus 2/89 participants on placebo experienced a serious adverse event (very low-quality evidence). One out of 90 participants experienced congestive heart failure in the vildagliptin group versus none in the placebo group (very low-quality evidence). There were no data on non-fatal myocardial infarction, stroke, health-related quality of life or socioeconomic effects reported.All-cause and cardiovascular mortality following treatment with GLP-1 analogues were rarely reported; one trial of exenatide reported that no participant died. Another trial of liraglutide 3.0 mg showed that 2/1501 in the liraglutide group versus 2/747 in the placebo group died after 160 weeks of treatment (very low-quality evidence).The incidence of T2DM following treatment with liraglutide 3.0 mg compared to placebo after 160 weeks was 26/1472 (1.8%) participants randomised to liraglutide versus 46/738 (6.2%) participants randomised to placebo (very low-quality evidence). The trial established the risk for (diagnosis of) T2DM as HbA1c 5.7% to 6.4% (6.5% or greater), fasting plasma glucose 5.6 mmol/L or greater to 6.9 mmol/L or less (7.0 mmol/L or greater) or two-hour post-load plasma glucose 7.8 mmol/L or greater to 11.0 mmol/L (11.1 mmol/L). Altogether, 70/1472 (66%) participants regressed from intermediate hyperglycaemia to normoglycaemia compared with 268/738 (36%) participants in the placebo group. The incidence of T2DM after the 12-week off-treatment extension period (i.e. after 172 weeks) showed that five additional participants were diagnosed T2DM in the liraglutide group, compared with one participant in the placebo group. After 12-week treatment cessation, 740/1472 (50%) participants in the liraglutide group compared with 263/738 (36%) participants in the placebo group had normoglycaemia.One trial used exenatide and 2/17 participants randomised to exenatide versus 1/16 participants randomised to placebo developed T2DM (very low-quality evidence). This trial did not provide a definition of T2DM. One trial reported serious adverse events in 230/1524 (15.1%) participants in the liraglutide 3.0 mg arm versus 96/755 (12.7%) participants in the placebo arm (very low quality evidence). There were no serious adverse events in the trial using exenatide. Non-fatal myocardial infarction was reported in 1/1524 participants in the liraglutide arm and in 0/55 participants in the placebo arm at 172 weeks (very low-quality evidence). One trial reported congestive heart failure in 1/1524 participants in the liraglutide arm and in 1/755 participants in the placebo arm (very low-quality evidence). Participants receiving liraglutide compared with placebo had a small mean improvement in the physical component of the 36-item Short Form scale showing a difference of 0.87 points (95% CI 0.17 to 1.58; P = 0.02; 1 trial; 1791 participants; very low-quality evidence). No trial evaluating GLP-1-analogues reported data on stroke, microvascular complications or socioeconomic effects.

AUTHORS' CONCLUSIONS

There is no firm evidence that DPP-4 inhibitors or GLP-1 analogues compared mainly with placebo substantially influence the risk of T2DM and especially its associated complications in people at increased risk for the development of T2DM. Most trials did not investigate patient-important outcomes.

3-bromopyruvate ameliorate autoimmune arthritis by modulating Th17/Treg cell differentiation and suppressing dendritic cell activation

Recent studies have shown that cellular metabolism plays an important role in regulating immune cell functions. In immune cell differentiation, both interleukin-17-producing T (Th17) cells and dendritic cells (DCs) exhibit increased glycolysis through the upregulation of glycolytic enzymes, such as hexokinase-2 (HK2). Blocking glycolysis with 2-deoxyglucose was recently shown to inhibit Th17 cell differentiation while promoting regulatory T (Treg) cell generation. However, 2-DG inhibits all isoforms of HK. Thus, it is unclear which isoform has a critical role in Th17 cell differentiation and in rheumatoid arthritis (RA) pathogenesis. Here we demonstrated that 3-bromopyruvate (BrPA), a specific HK2 inhibitor, significantly decreased the arthritis scores and the histological scores in SKG mice, with a significant increase in Treg cells, decrease in Th17 cells, and decrease in activated DCs in the spleen. In vitro, BrPA facilitated the differentiation of Treg cells, suppressed Th17 cells, and inhibited the activation of DCs. These results suggested that BrPA may be a therapeutic target of murine arthritis. Although the role of IL-17 is not clarified in the treatment of RA, targeting cell metabolism to alter the immune cell functions might lead to a new therapeutic strategy for RA.

Immune activation and immune aging in HIV infection

PURPOSE OF REVIEW

The development of serious non-AIDS-related pathologies typically associated with aging, and the premature immune aging that characterizes HIV-1-infected patients, even with suppressive antiretroviral therapy, have raised increasing concerns in recent years. Deciphering the causes of these phenomena is key for our understanding of HIV pathogenesis and for the clinical care of patients living with the virus.

RECENT FINDINGS

An important basis for the immune parallels between HIV infection and aging lies in the exhaustion of the lymphopoietic capacity of infected individuals, which eventually affects all compartments of the immune system. The alleged cause for these immune alterations, and the onset of age-related comorbidities, is the systemic chronic immune activation that is established in patients. However, there is a multiplicity of contributors to this immune activation.

SUMMARY

Our understanding of the precise link between immune activation and aging in HIV infection is complicated by the influence of coinfections and life style factors. Developing rational interventions to reduce the hyper-inflammatory status of HIV-1-infected patients requires a clearer delineation of the factors contributing to the increased levels of systemic immune activation.

Drug therapies for HIV-related metabolic disorders

INTRODUCTION

Human immunodeficiency virus (HIV) has become a chronic disease often associated with dyslipidaemia and insulin resistance. Combination antiretroviral therapy (cART) may contribute to metabolic disturbances, eventually leading to increased cardiovascular disease (CVR) in this population. Escalating interventions to decrease CVR include promoting a healthy lifestyle, such as quitting smoking, diet and regular exercise. If they do not achieve the goals, a change of cART should be considered, followed by or used concomitantly with the use of chemical therapies.

AREAS COVERED

The aim of this article is to review the available drug therapies for the treatment of metabolic disorders in HIV-infected patients and to examine their safety and effectiveness in this population. A review of the literature was conducted, highlighting the most relevant articles.

EXPERT OPINION

Switching strategies can be useful but its expected benefit is not high. Therefore, chemical intervention is often needed. Statins have been proven to reduce CVR in the general population and in HIV-infected patients. Simvastatin is contraindicated in patients treated with boosted PI due to interactions; atorvastatin is safe at submaximal dose and needs close monitoring, while pravastatin lacks lipid-lowering potency, and rosuvastatin and pitavastatin are safe. Ezetimibe and fibrates are also safe and effective in HIV-infected patients and can be used in combination with statins. The management of glucose homeostatic disorders in HIV-infected patients follows the same guidelines as in the general population. However, there are specific considerations with respect to the interactions of particular medications with cART. When drug therapy is needed, metformin is the first-line drug. Decisions regarding second- and third-line drugs should be carefully individualized.