The multifunctional or moonlighting protein CD26/DPPIV

Pattern of Expression of Genes Involved in Systemic Inflammation and Glutathione Metabolism Reveals Exacerbation of COPD

To test the hypothesis that they serve as systemic biomarkers of chronic obstructive pulmonary disease (COPD), we profiled the mRNA expression of enzymes connected to systemic inflammation and GSH metabolism in peripheral blood mononuclear cells (PBMCs). These were taken from patients displaying acute exacerbation of COPD (AE-COPD) and stable COPD, and also from non-obstructive smokers and non-smokers. The expression of poly(ADP-ribose) polymerase-1 was increased, but that of histone deacetylase 2 was decreased in association with AE-COPD. The expression of modulatory subunit of glutamyl-cysteine ligase was higher and that of its catalytic subunit, together with the expression of dipeptidyl peptidase 4, was lower in COPD patients compared with non-obstructive smokers and non-smokers. Leukotriene A4 hydrolase saw increased expression in patients with COPD according to disease severity compared to non-obstructive individuals, whereas the expression of GSH peroxidase increased in non-obstructive smokers and COPD patients with the growing number of pack-years smoked. The results corroborate COPD and its acute exacerbation as a complex systemic disorder demonstrating distinct associations with the expression of enzymes linked to inflammation and the regulation of GSH metabolism.

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.

In Vitro Investigation of Therapy-Induced Senescence and Senescence Escape in Breast Cancer Cells Using Novel Flow Cytometry-Based Methods

Although cellular senescence was originally defined as an irreversible form of cell cycle arrest, in therapy-induced senescence models, the emergence of proliferative senescence-escaped cancer cells has been reported by several groups, challenging the definition of senescence. Indeed, senescence-escaped cancer cells may contribute to resistance to cancer treatment. Here, to study senescence escape and isolate senescence-escaped cells, we developed novel flow cytometry-based methods using the proliferation marker Ki-67 and CellTrace CFSE live-staining. We investigated the role of a novel senescence marker (DPP4/CD26) and a senolytic drug (azithromycin) on the senescence-escaping ability of MCF-7 and MDA-MB-231 breast cancer cells. Our results show that the expression of DPP4/CD26 is significantly increased in both senescent MCF-7 and MDA-MB-231 cells. While not essential for senescence induction, DPP4/CD26 contributed to promoting senescence escape in MCF-7 cells but not in MDA-MB-231 cells. Our results also confirmed the potential senolytic effect of azithromycin in senescent cancer cells. Importantly, the combination of azithromycin and a DPP4 inhibitor (sitagliptin) demonstrated a synergistic effect in senescent MCF-7 cells and reduced the number of senescence-escaped cells. Although further research is needed, our results and novel methods could contribute to the investigation of the mechanisms of senescence escape and the identification of potential therapeutic targets. Indeed, DPP4/CD26 could be a promising marker and a novel target to potentially decrease senescence escape in cancer.

Contribution of amino acids in the active site of dipeptidyl peptidase 4 to the catalytic action of the enzyme

Dipeptidyl peptidase 4 (DP4)/CD26 regulates the biological function of various peptide hormones by releasing dipeptides from their N-terminus. The enzyme is a prominent target for the treatment of type-2 diabetes and various DP4 inhibitors have been developed in recent years, but their efficacy and side effects are still an issue. Many available crystal structures of the enzyme give a static picture about enzyme-ligand interactions, but the influence of amino acids in the active centre on binding and single catalysis steps can only be judged by mutagenesis studies. In order to elucidate their contribution to inhibitor binding and substrate catalysis, especially in discriminating the P1 amino acid of substrates, the amino acids R125, N710, E205 and E206 were investigated by mutagenesis studies. Our studies demonstrated, that N710 is essential for the catalysis of dipeptide substrates. We found that R125 is not important for dipeptide binding but interacts in the P1`position of the peptide backbone. In contrast to dipeptide substrates both amino acids play an essential role in the binding and arrangement of long natural substrates, particularly if lacking proline in the P1 position. Thus, it can be assumed that the amino acids R125 and N710 are important in the DP4 catalysed substrate hydrolysis by interacting with the peptide backbone of substrates up- and downstream of the cleavage site. Furthermore, we confirmed the important role of the amino acids E205 and E206. However, NP Y, displaying proline in P1 position, is still processed without the participation of E205 or E206.

Decreased circulating dipeptidyl peptidase-4 activity after short-term intensive insulin therapy predicts clinical outcomes in patients with newly diagnosed type 2 diabetes

Background

This study aims to investigate the changes in circulating dipeptidyl peptidase-4 (DPP-4) activity following short-term intensive insulin therapy (SIIT) in newly diagnosed type 2 diabetes (T2D) patients and to assess its potential in predicting long-term remission.

Methods

Ninety-five patients underwent SIIT for 2-3 weeks to attain and sustain near-normal glycemia. Insulin was then discontinued, and patients were followed for a year to evaluate glycemic outcomes. Biochemical tests, serum DPP-4 activity, and mixed meal tolerance tests were conducted at baseline, post-SIIT, and the 3-month follow-up.

Results

DPP-4 activity decreased from 44.08 ± 9.58 to 40.53 ± 8.83 nmol/min/mL after SIIT (P<0.001). After three months post-SIIT, DPP-4 activity remained stable in the remission group (39.63 ± 8.53 nmol/L) but increased in the non-remission group (42.34 ± 6.64 nmol/L). This resulted in a more pronounced decrease in DPP-4 activity from baseline in the remission group (-3.39 ± 8.90 vs. -1.10 ± 8.95, P = 0.035). Logistic regression analyses showed that patients with greater DPP-4 activity reduction had a higher likelihood of 1-year remission (70% vs. 51.1%, OR: 7.939 [1.829, 34.467], P = 0.006 in the fully adjusted model). A non-linear relationship between △DPP-4 and 1-year remission rate was observed, with a clear threshold and saturation effect.

Conclusion

Circulating DPP-4 activity significantly decreases after SIIT. The change in circulating DPP-4 activity during the 3-month post-treatment phase has the potential to predict long-term remission.

Preparation of Flexible Wavelength-Selective Metasurface for Infrared Radiation Regulation

Perpetual advancements in modern detection techniques have augmented the requirement of infrared camouflage; however, its development is impeded by multiband compatible regulation and curved application targets. Here, a flexible wavelength-selective metasurface based on two metal-dielectric-metal resonators is experimentally demonstrated for infrared radiation regulation with thermal management utilizing magnetic polariton. Low emissivity in atmosphere windows (infrared stealth) and high emissivity in the wavelength of 5-8 μm nonatmospheric window (radiative cooling) are simultaneously achieved. In comparison with conventional hard substrates, it is for the first time the composite wavelength-length metasurface is successfully prepared directly on a flexible polyimide film via applying polyimide double-sided tapes and S1805/LOR5A bilayer stack lift-off technology. Not only does this method successfully overcome the debonding problem of photoresist on the flexible substrate, but it also solves the bulging problem of the substrate as well as the limitation of high temperature. Besides, the temperature and infrared radiation distributions of flexible wavelength-selective metasurfaces with different curvatures are first investigated. The compared results reveal that the metasurface with larger curvature has a better infrared camouflage performance. Furthermore, the cycle stability of the flexible metasurface is tested, and the results show that the infrared radiation regulation is stable after 30 cycles with essentially no change. This study provides a guideline for preparing flexible composite metasurfaces and avoids the trouble of replacing the metal/dielectric material of the initial structure with a flexible material to improve the structure for application to curved surfaces, thus broadening implications in enhancing the effective bonding of metasurfaces to target surfaces.

Changes in intestinal morphology, number of mucus-producing cells and expression of coronavirus receptors APN, DPP4, ACE2 and TMPRSS2 in pigs with aging

Porcine enteric viral infections cause high morbidity and mortality in young piglets (<3 weeks). Later, these rates decrease with age. This age-dependent infectivity remains largely unexplored. This study investigated the changes in intestinal morphology, number of mucus-producing cells and expression level of coronavirus receptors in three age groups of pigs. Villus height and crypt depth increased with age from 3 days to 3 months in duodenum and ileum but not in mid-jejunum, where the villus height decreased from 580 µm at 3 days to 430 µm at 3 months. Enterocyte length-to-width ratio increased from 3 days to 3 months in all intestinal regions. The number of mucus-producing cells increased with age in the intestinal villi and crypts. The Brunner's glands of the duodenum contained the highest concentration of mucus-producing cells. The expression of coronavirus receptor APN was highest in the small intestinal villi at all ages. DPP4 expression slightly decreased over time in jejunum and ileum; it was highest in the ileal villi of 3-day-old piglets (70.2% of cells). ACE2 and TMPRSS2 positive cells increased with age in jejunal and ileal crypts and were particularly dominant in the ileal crypts (> 45% of cells). Except for the expression of DPP4 in the jejunum and ileum of young pigs, the expression pattern of the selected coronavirus receptors was very different and not correlated with the age-dependent susceptibility to viral infections. In contrast, the number of mucus-producing cells increased over time and may play an essential role in protecting enteric mucosae against intestinal viruses.

The many facets of CD26/dipeptidyl peptidase 4 and its inhibitors in disorders of the CNS - a critical overview

Dipeptidyl peptidase 4 is a serine protease that cleaves X-proline or X-alanine in the penultimate position. Natural substrates of the enzyme are glucagon-like peptide-1, glucagon inhibiting peptide, glucagon, neuropeptide Y, secretin, substance P, pituitary adenylate cyclase-activating polypeptide, endorphins, endomorphins, brain natriuretic peptide, beta-melanocyte stimulating hormone and amyloid peptides as well as some cytokines and chemokines. The enzyme is involved in the maintenance of blood glucose homeostasis and regulation of the immune system. It is expressed in many organs including the brain. DPP4 activity may be effectively depressed by DPP4 inhibitors. Apart from enzyme activity, DPP4 acts as a cell surface (co)receptor, associates with adeosine deaminase, interacts with extracellular matrix, and controls cell migration and differentiation. This review aims at revealing the impact of DPP4 and DPP4 inhibitors for several brain diseases (virus infections affecting the brain, tumours of the CNS, neurological and psychiatric disorders). Special emphasis is given to a possible involvement of DPP4 expressed in the brain.While prominent contributions of extracerebral DPP4 are evident for a majority of diseases discussed herein; a possible role of "brain" DPP4 is restricted to brain cancers and Alzheimer disease. For a number of diseases (Covid-19 infection, type 2 diabetes, Alzheimer disease, vascular dementia, Parkinson disease, Huntington disease, multiple sclerosis, stroke, and epilepsy), use of DPP4 inhibitors has been shown to have a disease-mitigating effect. However, these beneficial effects should mostly be attributed to the depression of "peripheral" DPP4, since currently used DPP4 inhibitors are not able to pass through the intact blood-brain barrier.

A Molecular Modeling Investigation of the Therapeutic Potential of Marine Compounds as DPP-4 Inhibitors

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by elevated levels of blood glucose due to insulin resistance or insulin-secretion defects. The development of diabetes is mainly attributed to the interaction of several complex pathogenic, genetic, environmental and metabolic processes. Dipeptidyl peptidase-4 (DPP-4) is a serine protease that cleaves X-proline dipeptides from the N-terminus of several polypeptides, including natural hypoglycemic incretin hormones. Inhibition of this enzyme restores and maintains glucose homeostasis, making it an attractive drug target for the management of T2DM. Natural products are important sources of bioactive agents for anti-T2DM drug discovery. Marine ecosystems are a rich source of bioactive products and have inspired the development of drugs for various human disorders, including diabetes. Here, structure-based virtual screening and molecular docking were performed to identify antidiabetic compounds from the Comprehensive Marine Natural Products Database (CMNPD). The binding characteristics of two shortlisted compounds, CMNPD13046 and CMNPD17868, were assessed using molecular dynamics simulations. Thus, this study provides insights into the potential antidiabetic activity and the underlying molecular mechanism of two compounds of marine origin. These compounds could be investigated further for the development of potent DPP-4 inhibitors.

Potential Treatment of COVID-19 with Traditional Chinese Medicine: What Herbs Can Help Win the Battle with SARS-CoV-2?

Traditional Chinese medicine (TCM) has been successfully applied worldwide in the treatment of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the pharmacological mechanisms underlying this success remain unclear. Hence, the aim of this review is to combine pharmacological assays based on the theory of TCM in order to elucidate the potential signaling pathways, targets, active compounds, and formulas of herbs that are involved in the TCM treatment of COVID-19, which exhibits combatting viral infections, immune regulation, and amelioration of lung injury and fibrosis. Extensive reports on target screening are elucidated using virtual prediction via docking analysis or network pharmacology based on existing data. The results of these reports indicate that an intricate regulatory mechanism is involved in the pathogenesis of COVID-19. Therefore, more pharmacological research on the natural herbs used in TCM should be conducted in order to determine the association between TCM and COVID-19 and account for the observed therapeutic effects of TCM against COVID-19.

Enhanced Diabetic Wound Healing Using Electrospun Biocompatible PLGA-Based Saxagliptin Fibrous Membranes

Delayed diabetic wound healing is an adverse event that frequently leads to limb disability or loss. A novel and promising vehicle for the treatment of diabetic wounds is required for clinical purposes. The biocompatible and resorbable poly (lactic-co-glycolic acid) (PLGA)-based fibrous membranes prepared by electrospinning that provide a sustained discharge of saxagliptin for diabetic wound healing were fabricated. The concentration of released saxagliptin in Dulbecco’s phosphate-buffered saline was analyzed for 30 days using high-performance liquid chromatography. The effectiveness of the eluted saxagliptin was identified using an endothelial progenitor cell migration assay in vitro and a diabetic wound healing in vivo. Greater hydrophilicity and water storage were shown in the saxagliptin-incorporated PLGA membranes than in the pristine PLGA membranes (both p < 0.001). For diabetic wound healing, the saxagliptin membranes accelerated the wound closure rate, the dermal thickness, and the heme oxygenase-1 level over the follicle areas compared to those in the pristine PLGA group at two weeks post-treatment. The saxagliptin group also had remarkably higher expressions of insulin-like growth factor I expression and transforming growth factor-β1 than the control group (p = 0.009 and p < 0.001, respectively) in diabetic wounds after treatment. The electrospun PLGA-based saxagliptin membranes exhibited excellent biomechanical and biological features that enhanced diabetic wound closure and increased the antioxidant activity, cellular granulation, and functionality.

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.

Exploring the management approaches of cytokines including viral infection and neuroinflammation for neurological disorders

Considerable evidence supports that cytokines are important mediators of pathophysiologic processes within the central nervous system (CNS). Numerous studies have documented the increased production of various cytokines in the human CNS in various neurological and neuropsychiatric disorders. Deciphering cytokine actions in the intact CNS has important implications for our understanding of the pathogenesis and treatment of these disorders. The purpose of this study is to discuss the recent research on treating cytokine storm and amyloids, including stroke, Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's condition, Multi-sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS). Neuroinflammation observed in neurological disorders has a pivotal role in exacerbating Aβ burden and tau hyperphosphorylation, suggesting that stimulating cytokines in response to an undesirable external response could be a checkpoint for treating neurological disorders. Furthermore, the pro-inflammatory cytokines help our immune system through a neuroprotective mechanism in clearing viral infection by recruiting mononuclear cells. This study reveals that cytokine applications may play a vital role in providing novel regulation and methods for the therapeutic approach to neurological disorders and the causes of the deregulation, which is responsible for neuroinflammation and viral infection. However, it needs to be further investigated to clarify better the mechanisms of cytokine release in response to various stimuli, which could be the central point for treating neurological disorders.

Therapeutic Perspectives of CD26 Inhibitors in Imune-Mediated Diseases

The enzymatic activity of CD26/DPP4 (dipeptidyl peptidase 4/DPP4) is highlighted in multiple studies to play a vital role in glucose metabolism by cleaving and inactivating the incretins glucagon-like peptide-1 (GLP) and gastric inhibitory protein (GIP). A large number of studies demonstrate that CD26 also plays an integral role in the immune system, particularly in T cell activation. CD26 is extensively expressed in immune cells, such as T cells, B cells, NK cells, dendritic cells, and macrophages. The enzymatic activity of CD26 cleaves and regulates numerous chomokines and cytokines. CD26 inhibitors have been widely used for the treatment of diabetes mellitus, while it is still under investigation as a therapy for immune-mediated diseases. In addition, CD26’s involvement in cancer immunology was also described. The review aims to summarize the therapeutic effects of CD26 inhibitors on immune-mediated diseases, as well as the mechanisms that underpin them.

cd26 Knockdown Negatively Affects Porcine Parthenogenetic Preimplantation Embryo Development

cd26 is ubiquitously distributed in the body, particularly in the endothelial and epithelial cells, with the highest expression in the kidney, liver, and small intestine. In humans, cd26 serves as a marker for the embryo implantation phase. However, little is known about the role of cd26 in porcine pre-implantation embryo development. Here, we aimed to examine siRNA-induced cd26 downregulation in the cytoplasm of MII oocytes, to determine whether cd26 is involved in the regulation of porcine pre-implantation embryonic development. The cd26 siRNA was micro-injected into the cytoplasm of MII oocytes, which were then parthenogenetically activated electrically in a medium containing 0.3M Mannitol. Inhibition of the cd26 expression did not affect cleavage but stopped development in the blastocyst stage. Additionally, the cd26 siRNA-treated blastocysts had significantly more apoptotic cells than the untreated blastocysts. Among the 579 transcripts evaluated with transcriptome resequencing, 38 genes were differentially expressed between the treatment and control blastocysts (p < 0.05). Twenty-four genes were upregulated in cd26 siRNA-injected blastocysts, whereas 14 were downregulated. These genes are involved in apoptosis, accumulation of reactive oxygen species, and aberrant expression of ribosomal protein genes. Our results indicate that cd26 is required for proper porcine parthenogenetic activation during embryonic development.

Potential neurological manifestations of COVID-19: a narrative review

Neurological manifestations are increasingly reported in a subset of COVID-19 patients. Previous infections related to coronaviruses, namely Severe Acute Respiratory Syndrome (SARS) and Middle Eastern Respiratory Syndrome (MERS) also appeared to have neurological effects on some patients. The viruses associated with COVID-19 like that of SARS enters the body via the ACE-2 receptors in the central nervous system, which causes the body to balance an immune response against potential damage to nonrenewable cells. A few rare cases of neurological sequelae of SARS and MERS have been reported. A growing body of evidence is accumulating that COVID-19, particularly in severe cases, may have neurological consequences although respiratory symptoms nearly always develop prior to neurological ones. Patients with preexisting neurological conditions may be at elevated risk for COVID-19-associated neurological symptoms. Neurological reports in COVID-19 patients have described encephalopathy, Guillain-Barré syndrome, myopathy, neuromuscular disorders, encephalitis, cephalgia, delirium, critical illness polyneuropathy, and others. Treating neurological symptoms can pose clinical challenges as drugs that suppress immune response may be contraindicated in COVID-19 patients. It is possible that in some COVID-19 patients, neurological symptoms are being overlooked or misinterpreted. To date, neurological manifestations of COVID-19 have been described largely within the disease trajectory and the long-term effects of such manifestations remain unknown.

Low levels of soluble DPP4 among Saudis may have constituted a risk factor for MERS endemicity

Most of the cases of Middle East respiratory syndrome coronavirus (MERS-CoV) were reported in Saudi Arabia. Dipeptidyl peptidase-4 (DPP4) was identified as the receptor for the virus. The level of soluble DPP4 (sDPP4) was found to be reduced in MERS-CoV infected patients while high levels of sDPP4 were suggested to be protective against MERS-CoV in animal models. We investigated whether the Saudi population has lower levels of sDPP4 which makes them more susceptible to MERS-CoV infection and, therefore, could explain the larger number of cases from the country. Blood samples were collected from 219 Saudi blood donors and 200 blood donors from other ethnic groups. The plasma level of sDPP4 was measured by ELISA and the following SNPs in the DPP4 gene; rs35128070, rs1861978, rs79700168, and rs17574, were genotyped by TaqMan SNP genotyping assay. The average level of plasma sDDP4 was significantly lower in Saudis than other Arabs and non-Arabs (P value 0.0003 and 0.012, respectively). The genotypes AG of rs35128070 and GT of rs1861978 were significantly associated with lower sDPP4 among Saudis (P value 0.002 for each). While both genotypes AA and AG of rs79700168 and rs17574 were associated with significantly lower average sDPP4 level in Saudis compared to other ethnic groups (P value 0.031 and 0.032, and 0.027 and 0.014, respectively). Herein, we report that the Saudi population has lower levels of plasma sDPP4 than other ethnic groups, which is associated with genetic variants in the DPP4 gene. This may have contributed to increase the susceptibility of the Saudi population to MERS-CoV infection and could be a factor in the long-lasting persistence of the virus in the country.

SARS-COV-2 - the pandemic of the XXI century, clinical manifestations - neurological implications

In December 2019, in Wuhan, China, the first cases of infection with SARS-CoV 2 responsible for COVID-19 disease were identified. SARS-CoV 2 was declared a pandemic on March 11, 2020, and since then has attracted the medical world's attention. The threat to humans' health that this emerging pandemic could leave raises awareness on the importance of understanding the mechanisms that underlie the developing conditions. The epidemiology, clinical picture, and pathogenesis of COVID-19 show that this virus presents new strategies to overcome the past defensive medicine. While all the current data has focused on the pulmonary and cardiovascular manifestations, little has been written about the neurological implications of the disease. This review updates new clinical aspects that SARS-CoV 2 expresses in humans by focusing primarily on neurological manifestations. The damage to the nervous system became more apparent - anosmia, ageusia, polyneuritis, meningitis, meningoencephalitis, stroke, acute necrotizing encephalopathy. Oxygen therapy is vital for those in critical health situations. Finally, prevention is the most important element in breaking the epidemiological chain.

CD26/DPP-4 in Chronic Myeloid Leukemia

CD26 expression is altered in many solid tumors and hematological malignancies. Recently, it has been demonstrated that it is a specific marker expressed on LSCs of CML, both in BM and PB samples, and absent on CD34+/CD38− stem cells in normal subjects or on LSCs of other myeloid neoplasms. CD26+ LSCs have been detected by flow-cytometry assays in all PB samples of Chronic-Phase CML patients evaluated at diagnosis. Additionally, it has been demonstrated that most CML patients undergoing Tyrosine Kinase Inhibitors (TKIs) treatment still harbored circulating measurable residual CD26+ LSCs, even when displaying a consistent deep molecular response without any significant association among the amounts of BCR-ABL transcript and CD26+ LSCs. Preliminary data of our Italian prospective multicenter study showed that CML patients with a poorer response presented with a higher number of CD26+ LSCs at diagnosis. These data confirmed that CD26 is a specific marker of CML and suggest that it could be considered for the monitoring of therapeutic responses.

StackDPPIV: A novel computational approach for accurate prediction of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides

The development of efficient and effective bioinformatics tools and pipelines for identifying peptides with dipeptidyl peptidase IV (DPP-IV) inhibitory activities from large-scale protein datasets is of great importance for the discovery and development of potential and promising antidiabetic drugs. In this study, we present a novel stacking-based ensemble learning predictor (termed StackDPPIV) designed for identification of DPP-IV inhibitory peptides. Unlike the existing method, which is based on single-feature-based methods, we combined five popular machine learning algorithms in conjunction with ten different feature encodings from multiple perspectives to generate a pool of various baseline models. Subsequently, the probabilistic features derived from these baseline models were systematically integrated and deemed as new feature representations. Finally, in order to improve the predictive performance, the genetic algorithm based on the self-assessment-report was utilized to determine a set of informative probabilistic features and then used the optimal one for developing the final meta-predictor (StackDPPIV). Experiment results demonstrated that StackDPPIV could outperform its constituent baseline models on both the training and independent datasets. Furthermore, StackDPPIV achieved an accuracy of 0.891, MCC of 0.784 and AUC of 0.961, which were 9.4%, 19.0% and 11.4%, respectively, higher than that of the existing method on the independent test. Feature analysis demonstrated that our feature representations had more discriminative ability as compared to conventional feature descriptors, which highlights the combination of different features was essential for the performance improvement. In order to implement the proposed predictor, we had built a user-friendly online web server at http://pmlabstack.pythonanywhere.com/StackDPPIV.

Neurological manifestations of coronavirus infections, before and after COVID-19: a review of animal studies

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus, which was first identified in December 2019 in China, has resulted in a yet ongoing viral pandemic. Coronaviridae could potentially cause several disorders in a wide range of hosts such as birds and mammals. Although infections caused by this family of viruses are predominantly limited to the respiratory tract, Betacoronaviruses are potentially able to invade the central nervous system (CNS) as well as many other organs, thereby inducing neurological damage ranging from mild to lethal in both animals and humans. Over the past two decades, three novel CoVs, SARS-CoV-1, MERS-CoV, and SARS-CoV-2, emerging from animal reservoirs have exhibited neurotropic properties causing severe and even fatal neurological diseases. The pathobiology of these neuroinvasive viruses has yet to be fully known. Both clinical features of the previous CoV epidemics (SARS-CoV-1 and MERS-CoV) and lessons from animal models used in studying neurotropic CoVs, especially SARS and MERS, constitute beneficial tools in comprehending the exact mechanisms of virus implantation and in illustrating pathogenesis and virus dissemination pathways in the CNS. Here, we review the animal research which assessed CNS infections with previous more studied neurotropic CoVs to demonstrate how experimental studies with appliable animal models can provide scientists with a roadmap in the CNS impacts of SARS-CoV-2. Indeed, animal studies can finally help us discover the underlying mechanisms of damage to the nervous system in COVID-19 patients and find novel therapeutic agents in order to reduce mortality and morbidity associated with neurological complications of SARS-CoV-2 infection.

The Serine Protease CD26/DPP4 in Non-Transformed and Malignant T Cells

Simple Summary

The transmembrane serine protease CD26/Dipeptidylpeptidase 4 modulates T-cell activation, proliferation, and effector function. Due to their remarkable tumoricidal properties CD26-positive T cells are considered promising candidates for T cell-based immunotherapies while in cutaneous T cell lymphoma CD26/DPP4 expression patterns are established markers for diagnosis and possibly prognosis. With a focus on T cells, we review current knowledge on the regulation of CD26/DPP4 expression and release, its implication in T-cell effector function and the suitability CD26/DPP4 as a diagnostic and/or prognostic factor in T-cell malignancies.

Abstract

CD26/Dipeptidylpeptidase 4 is a transmembrane serine protease that cleaves off N-terminal dipeptides. CD26/DPP4 is expressed on several immune cell types including T and NK cells, dendritic cells, and activated B cells. A catalytically active soluble form of CD26/DPP4 can be released from the plasma membrane. Given its wide array of substrates and interaction partners CD26/DPP4 has been implicated in numerous biological processes and effects can be dependent or independent of its enzymatic activity and are exerted by the transmembrane protein and/or the soluble form. CD26/DPP4 has been implicated in the modulation of T-cell activation and proliferation and CD26/DPP4-positive T cells are characterized by remarkable anti-tumor properties rendering them interesting candidates for T cell-based immunotherapies. Moreover, especially in cutaneous T-cell lymphoma CD26/DPP4 expression patterns emerged as an established marker for diagnosis and treatment monitoring. Surprisingly, besides a profound knowledge on substrates, interaction partners, and associated signal transduction pathways, the precise role of CD26/DPP4 for T cell-based immune responses is only partially understood.

MERS-CoV infection causes brain damage in human DPP4-transgenic mice through complement-mediated inflammation

The highly pathogenic Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a severe respiratory virus. Recent reports indicate additional central nervous system (CNS) involvement. In this study, human DPP4 transgenic mice were infected with MERS-CoV, and viral antigens were first detected in the midbrain-hindbrain 4 days post-infection, suggesting the virus may enter the brainstem via peripheral nerves. Neurons and astrocytes throughout the brain were infected, followed by damage of the blood brain barrier (BBB), as well as microglial activation and inflammatory cell infiltration, which may be caused by complement activation based on the observation of deposition of complement activation product C3 and high expression of C3a receptor (C3aR) and C5a receptor (C5aR1) in neurons and glial cells. It may be concluded that these effects were mediated by complement activation in the brain, because of their reduction resulted from the treatment with mouse C5aR1-specific mAb. Such mAb significantly reduced nucleoprotein expression, suppressed microglial activation and decreased activation of caspase-3 in neurons and p38 phosphorylation in the brain. Collectively, these results suggest that MERS-CoV infection of CNS triggers complement activation, leading to inflammation-mediated damage of brain tissue, and regulating of complement activation could be a promising intervention and adjunctive treatment for CNS injury by MERS-CoV and other coronaviruses.

A comprehensive review of COVID-19 biology, diagnostics, therapeutics, and disease impacting the central nervous system

The ongoing COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a highly transmissible disease. SARS-CoV-2 is estimated to have infected over 153 million people and to have caused over 3.2 million global deaths since its emergence in December 2019. SARS-CoV-2 is the seventh coronavirus known to infect humans, and like other coronaviruses, SARS-CoV-2 infection is characterized by a variety of symptoms including general flu-like symptoms such as a fever, sore throat, fatigue, and shortness of breath. Severe cases often display signs of pneumonia, lymphopenia, acute kidney injury, cardiac injury, cytokine storms, lung damage, acute respiratory distress syndrome (ARDS), multiple organ failure, sepsis, and death. There is evidence that around 30% of COVID-19 cases have central nervous system (CNS) or peripheral nervous system (PNS) symptoms along with or in the absence of the previously mentioned symptoms. In cases of CNS/PNS impairments, patients display dizziness, ataxia, seizure, nerve pain, and loss of taste and/or smell. This review highlights the neurological implications of SARS-CoV-2 and provides a comprehensive summary of the research done on SARS-CoV-2 pathology, diagnosis, therapeutics, and vaccines up to May 5.

Potential Effects of Coronaviruses on the Liver: An Update

The coronaviruses that cause notable diseases, namely, severe acute respiratory syndrome (SARS), middle east respiratory syndrome (MERS) and coronavirus disease 2019 (COVID-19), exhibit remarkable similarities in genomic components and pathogenetic mechanisms. Although coronaviruses have widely been studied as respiratory tract pathogens, their effects on the hepatobiliary system have seldom been reported. Overall, the manifestations of liver injury caused by coronaviruses typically involve decreased albumin and elevated aminotransferase and bilirubin levels. Several pathophysiological hypotheses have been proposed, including direct damage, immune-mediated injury, ischemia and hypoxia, thrombosis and drug hepatotoxicity. The interaction between pre-existing liver disease and coronavirus infection has been illustrated, whereby coronaviruses influence the occurrence, severity, prognosis and treatment of liver diseases. Drugs and vaccines used for treating and preventing coronavirus infection also have hepatotoxicity. Currently, the establishment of optimized therapy for coronavirus infection and liver disease comorbidity is of significance, warranting further safety tests, animal trials and clinical trials.

Application of machine learning methods for the development of antidiabetic drugs

Diabetes is a chronic non-communicable disease caused by several different routes, which has attracted increasing attention. In order to speed up the development of new selective drugs, machine learning (ML) technology has been applied in the process of diabetes drug development, which opens up a new blueprint for drug design. This review provides a comprehensive portrayal of the application of ML in antidiabetic drug use.

Middle East Respiratory Syndrome (MERS) Virus-Pathophysiological Axis and the Current Treatment Strategies

Middle East respiratory syndrome (MERS) is a lethal respiratory disease with its first case reported back in 2012 (Jeddah, Saudi Arabia). It is a novel, single-stranded, positive-sense RNA beta coronavirus (MERS-CoV) that was isolated from a patient who died from a severe respiratory illness. Later, it was found that this patient was infected with MERS. MERS is endemic to countries in the Middle East regions, such as Saudi Arabia, Jordan, Qatar, Oman, Kuwait and the United Arab Emirates. It has been reported that the MERS virus originated from bats and dromedary camels, the natural hosts of MERS-CoV. The transmission of the virus to humans has been thought to be either direct or indirect. Few camel-to-human transmissions were reported earlier. However, the mode of transmission of how the virus affects humans remains unanswered. Moreover, outbreaks in either family-based or hospital-based settings were observed with high mortality rates, especially in individuals who did not receive proper management or those with underlying comorbidities, such as diabetes and renal failure. Since then, there have been numerous reports hypothesising complications in fatal cases of MERS. Over the years, various diagnostic methods, treatment strategies and preventive measures have been strategised in containing the MERS infection. Evidence from multiple sources implicated that no treatment options and vaccines have been developed in specific, for the direct management of MERS-CoV infection. Nevertheless, there are supportive measures outlined in response to symptom-related management. Health authorities should stress more on infection and prevention control measures, to ensure that MERS remains as a low-level threat to public health.

Anti-inflammatory Effects of Empagliflozin and Gemigliptin on LPS-Stimulated Macrophage via the IKK/NF-κB, MKK7/JNK, and JAK2/STAT1 Signalling Pathways

Background

Sodium-glucose cotransporter 2 (SGLT2) and dipeptidyl peptidase-4 (DPP-4) inhibitors are glucose-lowering drugs whose anti-inflammatory properties have recently become useful in tackling metabolic syndromes in chronic inflammatory diseases, including diabetes and obesity. We investigated whether empagliflozin (SGLT2 inhibitor) and gemigliptin (DPP-4 inhibitor) improve inflammatory responses in macrophages, identified signalling pathways responsible for these effects, and studied whether the effects can be augmented with dual empagliflozin and gemigliptin therapy.

Methods

RAW 264.7 macrophages were first stimulated with lipopolysaccharide (LPS), then cotreated with empagliflozin, gemigliptin, or empagliflozin plus gemigliptin. We conducted quantitative RT-PCR (qRT-PCR) to determine the most effective anti-inflammatory doses without cytotoxicity. We performed ELISA and qRT-PCR for inflammatory cytokines and chemokines and flow cytometry for CD80, the M1 macrophage surface marker, to evaluate the anti-inflammatory effects of empagliflozin and gemigliptin. NF-κB, MAPK, and JAK2/STAT signalling pathways were examined via Western blotting to elucidate the molecular mechanisms of anti-inflammation.

Results

LPS-stimulated CD80⁺ M1 macrophages were suppressed by coincubation with empagliflozin, gemigliptin, and empagliflozin plus gemigliptin, respectively. Empagliflozin and gemigliptin (individually and combined) inhibited prostaglandin E₂ (PGE₂) release and COX-2, iNOS gene expression in LPS-stimulated RAW 264.7 macrophages. These three treatments also attenuated the secretion and mRNA expression of proinflammatory cytokines, such as TNF-α, IL-1β, IL-6, and IFN-γ, and proinflammatory chemokines, such as CCL3, CCL4, CCL5, and CXCL10. All of them blocked NF-κB, JNK, and STAT1/3 phosphorylation through IKKα/β, MKK4/7, and JAK2 signalling.

Conclusions

Our study demonstrated the anti-inflammatory effects of empagliflozin and gemigliptin via IKK/NF-κB, MKK7/JNK, and JAK2/STAT1 pathway downregulation in macrophages. In all cases, combined empagliflozin and gemigliptin treatment showed greater anti-inflammatory properties.

Dipeptidyl peptidase 4 inhibitors: Applications in innate immunity?

Dipeptidyl peptidase (DPP)-4 inhibitors are a class of orally available, small molecule inhibitors that prolong the insulinotropic activity of the incretin hormone glucagon-like peptide-1 (GLP-1) and are highly effective for the treatment of Type-2 diabetes. DPP4 can also cleave several immunoregulatory peptides including chemokines. Emerging evidence continues to implicate DPP4 inhibitors as immunomodulators, with recent findings suggesting DPP4 inhibitors modify specific aspects of innate immunity. This review summarises recent insights into how DPP4 inhibitors could be implicated in endothelial, neutrophil and monocyte/macrophage mediated immunity. Additionally, this review highlights additional avenues of research with DPP4 inhibitors in the context of the COVID-19 pandemic.

Dipeptidyl peptidase IV is required for endometrial carcinoma cell proliferation and tumorigenesis via the IL-6/STAT3 pathway

AIM

To study the functions and signaling pathways controlled by dipeptidyl peptidase IV (DPPIV) in endometrial carcinoma (EC).

METHODS

DPPIV expression in EC cells was detected by flow cytometry, reverse transcription-polymerase chain reaction analysis and Western blot. Interleukin-6 (IL-6) expression in the supernatant was measured by enzyme-linked immunosorbent assay. The protein levels of signal transducers and activators of transcription-3 (STAT3), phosphorylate STAT3, cellular Myc, and vascular endothelial growth factor in EC cells were measured by Western blot. Colony formation assays were used to assess the clonogenicity of EC cells. Ki67 immunostaining and cell counting were used to test the proliferative ability of EC cells. Nude mouse tumorigenicity assay was used to confirm DPPIV promotes the tumorigenicity of EC cells. A cell counting kit-8 assay was used to determine the half-maximal inhibitory concentration of sitagliptin.

RESULTS

Overexpression of DPPIV in EC cells with low DPPIV expression promoted cell proliferation in vitro (p < 0.01) and enhanced tumorigenicity in vivo (p < 0.05). Conversely, knocking down DPPIV expression in EC cells with high DPPIV expression inhibited cell proliferation (p < 0.01) and in vivo tumorigenicity (p < 0.01). DPPIV promoted EC cell proliferation via activation of IL-6/STAT3 signaling pathway, and that IL-6 could trigger a positive feedback loop that increased DPPIV expression (p < 0.01). Furthermore, the DPPIV inhibitor reduced STAT3 expression (p < 0.01) and inhibited growth of EC cells (p < 0.001).

CONCLUSION

DPPIV enhances the properties that allow tumorigenesis in EC via IL-6 and STAT3 signaling.

Urinary exosomal CD26 is associated with recovery from acute kidney injury in intensive care units: a prospective cohort study

OBJECTIVES

Currently there is no validated method to predict renal reversal and recovery after acute kidney injury (AKI). As exosomes have the potential for AKI prognosis and CD26 is involved in the mechanisms in AKI, this study aims to investigate whether urinary exosomal CD26 is associated with renal-related outcomes and explore its prospect as a novel prognosis biomarker.

METHODS

This was a single-center, prospective cohort study. A total of 133 AKI patients and 68 non-AKI patients admitted to ICU in Qilu Hospital Shandong University from January 2017 to January 2018. Urine samples were collected at enrollment and the relative expression of CD26 (CD26 percentage) in urinary exosomes was examined, that was then categorized into a low-CD26 level and a high-CD26 level.

RESULTS

CD26 percentage was significantly lower in the AKI cohort than in the control cohort. Within the AKI cohort, a high-CD26 level was associated with lower incidence of major adverse kidney events within 90 days, but higher incidence of reversal within 28 days. In AKI survivors, a high-CD26 level had a 4.67-, 3.50- and 4.66-fold higher odds than a low-CD26 level for early reversal, recovery and reversal, respectively, after adjustment for clinical factors. Prediction performance was moderate for AKI survivors but improved for non-septic AKI survivors.

CONCLUSIONS

Urinary exosomal CD26 is associated with renal reversal and recovery from AKI and is thus a promising prognosis biomarker.

Dipeptidylpeptidase-4 levels and DPP4 gene polymorphisms in patients with COVID-19. Association with disease and with severity

Background

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes de COVID-19 disease use as a principal receptor the angiotensin-converting enzyme-2 (ACE2). It has been suggested that dipeptidyl peptidase-4 (DPP4) can be another possible receptor for this virus. The present study aimed to establish if the DPP4 levels and DPP4 polymorphisms are associated with COVID-19 disease and its severity.

Methods

The study included 107 COVID-19 patients and 263 matched-healthy controls. Fifty patients required invasive mechanical ventilation. The DPP4 was quantified in serum using the Bioplex system. Based on the previous results and the functional prediction analysis, we select for the study 5 DPP4 polymorphisms (rs12617336, rs12617656, rs1558957, rs3788979, and rs17574) and these were determined using the 5´exonuclease TaqMan assays.

Results

Low levels of DPP4 were observed in COVID-19 patients (46.5 [33.1–57.7] ng/mL) when compared to healthy controls (125.3 [100.3–157.3] ng/mL) (P < 0.0001). Also, patients that required mechanical ventilation showed lower DPP4 levels (42.8 [29.8–56.9] ng/mL) than those that did not need this procedure (49.2 [39.9–65.6] ng/mL) (P = 0.012). DPP4 levels correlated negatively with age, fibrinogen, and platelet levels, and positively with albumin, alanine aminotransferase, and percentage of neutrophils. The DPP4 rs3788979 polymorphism was associated with a high risk of COVID-19 disease and, the TT genotype carriers had the lowest DPP4 levels.

Conclusions

In summary, in the present study, an association of low levels of DPP4 with COVID-19 disease and severity was found. The association of the DPP4 rs3788979 polymorphism with COVID-19 is also reported.

The mechanism of sitagliptin inhibition of colorectal cancer cell lines' metastatic functionalities

The cell membrane glycoprotein CD26 with peptidase activity (DPP4) and/or its soluble CD26/DPP4 counterpart expression and/or activity are altered in several cancers. Its role in metastasis development was recently highlighted by the discovery of CD26⁺ cancer stem cell subsets and the fact that clinical DPP4 inhibitors showed antimetastatic effects in animal models. Also, diabetic patients treated with the DPP4 inhibitor sitagliptin showed greater overall survival after colorectal or lung cancer surgery than patients under other diabetic therapies. However, the mechanism of action of these inhibitors in this context is unclear. We studied the role of CD26 and its DPP4 enzymatic activity in malignant cell features such as cell-to-cell homotypic aggregation, cancer cell motility, and invasion in a panel of human colorectal cancer (CRC) cell lines, avoiding models that include the physiological role of DPP4 in chemotaxis. Present results indicate that CD26 participates in the induction of cell invasion, motility, and aggregation of CD26-positive CRC cell lines. Moreover, only invasion and motility assays, which are collagen matrix-dependent, showed a decrease upon treatment with the DPP4 inhibitor sitagliptin. Sitagliptin showed opposite effects to those of transforming growth factor-β1 on epithelial-to-mesenchymal transition and cell cycle, but this result does not explain its CD26/DPP4-dependent effect. These results contribute to the elucidation of the molecular mechanisms behind sitagliptin inhibition of metastatic traits. At the same time, this role of sitagliptin may help to define areas of medicine where DPP4 inhibitors might be introduced. However, they also suggest that additional tools against CD26 as a target might be used or developed for metastasis prevention in addition to gliptins.

Functional Dissection of CD26 and Its Pharmacological Inhibition by Sitagliptin During Skin Wound Healing

BACKGROUND Skin fibroblasts are primary mediators underlying wound healing and therapeutic targets in scar prevention and treatment. CD26 is a molecular marker to distinguish fibroblast subpopulations and plays an important role in modulating the biological behaviors of dermal fibroblasts and influencing skin wound repair. Therapeutic targeting of specific fibroblast subsets is expected to reduce skin scar formation more efficiently. MATERIAL AND METHODS Skin burn and excisional wound healing models were surgically established in mice. The expression patterns of CD26 during wound healing were determined by immunohistochemical staining, real-time RT-PCR, and western blot assays. Normal fibroblasts from intact skin (NFs) and fibroblasts in wounds (WFs) were isolated and sorted by fluorescence-activated cell sorting (FACS) into 4 subgroups - CD26⁺ NFs, CD26⁻ NFs, CD26⁺ WFs, and CD26⁻ WFs - for comparisons of their capacities of proliferation, migration, and collagen synthesis. Pharmacological inhibition of CD26 by sitagliptin in skin fibroblasts and during wound healing were further assessed both in vitro and in vivo. RESULTS Increased CD26 expression was observed during skin wound healing in both models. The CD26⁺ fibroblasts isolated from wounds had significantly stronger abilities to proliferate, migrate, and synthesize collagen than other fibroblast subsets. Sitagliptin treatment potently diminished CD26 expression, impaired the proliferation, migration, and collagen synthesis of fibroblasts in vitro, and diminished scar formation in vivo. CONCLUSIONS Our data reveal that CD26 is functionally involved in skin wound healing by regulating cell proliferation, migration, and collagen synthesis in fibroblasts. Pharmacological inhibition of CD26 by sitagliptin might be a viable strategy to reduce skin scar formation.

Clinical features and potential mechanism of coronavirus disease 2019-associated liver injury

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, has posed a serious threat to global public health security. With the increase in the number of confirmed cases globally, the World Health Organization has declared the outbreak of COVID-19 an international public health emergency. Despite atypical pneumonia as the primary symptom, liver dysfunction has also been observed in many clinical cases and is associated with the mortality risk in patients with COVID-19, like severe acute respiratory syndrome and Middle East respiratory syndrome. Here we will provide a schematic overview of the clinical characteristics and the possible mechanisms of liver injury caused by severe acute respiratory syndrome coronavirus 2 infection, which may provide help for optimizing the management of liver injury and reducing mortality in COVID-19 patients.

Epidemiology and pathobiology of SARS-CoV-2 (COVID-19) in comparison with SARS, MERS: An updated overview of current knowledge and future perspectives

Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) is the causative etiology of ‘Corona Virus Disease-2019’ (COVID-19); formerly referred as ‘novel-Coronavirus-2019’. It was originated in Wuhan city, Hubei province, China in early December 2019. The World Health Organization (WHO) declared it as ‘Public Health Emergency of International Concern’ due to their rapid transmission and causing public and health-care-related casualties worldwide. This review provides an updated overview of COVID-19 (SARS-CoV-2), in comparison with the etiologies of the same group viz. SARS and MERS and also its future perspectives for planning appropriate strategies for prevention, control and treatment modalities to avert similar catastrophe in near future.

Neurological manifestations of coronavirus infections: role of angiotensin-converting enzyme 2 in COVID-19

AIM OF THE STUDY

In December 2019, a highly pathogenic coronavirus called SARS-CoV-2 (formerly identified as 2019-nCoV) appeared in Wuhan, China, and has since been spreading rapidly around the world. we reviewed the neurological manifestations of this infection and the potential of ACE2 in the nervous system.

MATERIALS AND METHODS

Six databases (Medline, Scopus, Embase, Web of Science, WHO, and google scholar) were searched and screened by the authors for having appropriate information about covid-19. Finally, 72 studies were identified, summarized and reviewed.

RESULT

The most specific manifestation of SARS-CoV-2 patients is pulmonary distress, and several patients admitted to intensive care units were not able to breathe spontaneously. In addition, the SARS-CoV-2 outbreak has a significant effect on nervous systems and may even lead to serious neurological damage. The neuroinvasive pathobiology is still not fully elucidated and thus the effect of CoV infections on the nervous system needs to be explored. The spike protein of the virus and the angiotensin-converting enzyme 2 (ACE2) lead to the presence of both SARS-CoV and SARS-CoV-2 in the cells and, subsequently, decreased ACE2 expression.

CONCLUSION

The therapeutic possibilities of ACE2 antibody, ACE2-derived peptides, and small molecule blockers of ACE2 include a receptor-binding domain blocking approach. Hence, future studies of ACE2 may be very helpful in discovering a therapy for SARS-CoV-2.

The Prevalence of Gastrointestinal Symptoms, Abnormal Liver Function, Digestive System Disease and Liver Disease in COVID-19 Infection: A Systematic Review and Meta-Analysis

BACKGROUND

The worldwide outbreak of COVID-19 infected millions of people. Some patients had gastrointestinal (GI) symptoms, abnormal liver function, digestive system disease and liver disease.

AIM

To investigate the prevalence of GI symptoms, abnormal liver function, digestive system disease and liver disease in patients with COVID-19 by a systematic review and meta-analysis.

METHODS

We searched PubMed, Ovid Embase, Medline, and 2 Chinese databases. Primary outcomes were the prevalence of GI symptoms, abnormal liver function, digestive system disease, and liver disease. Different studies were included in different subset analysis. These outcomes were estimated with proportions, odds ratio, 95% confidence interval (CI) and P-value by Stata SE 15.1.

RESULTS

Thirty-one studies involving 4682 patients were included. The most significant GI symptoms were diarrhea (0.08, 95% CI: 0.06-0.11) and anorexia (0.17, 95% CI: 0.06-0.27). The most significant abnormal liver function was increased alanine aminotransferase (ALT) (0.25, 95% CI: 0.16-0.33). A total of 5% of the patients had digestive system disease (95% CI: 0.02-0.08). A total of 3% of the patients had liver disease (95% CI: 0.02-0.05). The prevalence of nausea and vomiting, diarrhea, abnormal liver function, digestive system disease, and liver disease was higher in Wuhan group. The prevalence of diarrhea was higher in non-China group. Patients in severe/intensive care unit group were more likely to have diarrhea, anorexia, abdominal pain increased aspartate aminotransferase, and increased ALT.

CONCLUSION

The most significant GI symptoms were anorexia and diarrhea. The most significant abnormal liver function was increased ALT. Severe patients were more likely to have GI symptoms and abnormal liver function.

The recent outbreaks of human coronaviruses: A medicinal chemistry perspective

Coronaviruses (CoVs) infect both humans and animals. In humans, CoVs can cause respiratory, kidney, heart, brain, and intestinal infections that can range from mild to lethal. Since the start of the 21st century, three β-coronaviruses have crossed the species barrier to infect humans: severe-acute respiratory syndrome (SARS)-CoV-1, Middle East respiratory syndrome (MERS)-CoV, and SARS-CoV-2 (2019-nCoV). These viruses are dangerous and can easily be transmitted from human to human. Therefore, the development of anticoronaviral therapies is urgently needed. However, to date, no approved vaccines or drugs against CoV infections are available. In this review, we focus on the medicinal chemistry efforts toward the development of antiviral agents against SARS-CoV-1, MERS-CoV, SARS-CoV-2, targeting biochemical events important for viral replication and its life cycle. These targets include the spike glycoprotein and its host-receptors for viral entry, proteases that are essential for cleaving polyproteins to produce functional proteins, and RNA-dependent RNA polymerase for viral RNA replication.

Potential pharmacological approach in the regulation of angiotensin-II conversion enzyme and dipeptidyl-peptidase 4 in diabetic COVID-19 patients

The global pandemic caused by coronavirus disease 2019 (COVID-19) has caused more than 1 million deaths worldwide. Some vaccines in clinical trials have reached stage 3. In the meantime, the understanding of biological and pathophysiological mechanisms of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) infection is still unclear, such as the role that angiotensin-II conversion enzyme (ACE-2) and dipeptidyl-peptidase 4 (DPP-IV) may play in patients with diabetes related to COVID-19. The individual with diabetes is a known COVID-19 risk patient. Probably, the pharmacological regulation of the angiotensin renin system and ACE-2 on the one hand, and of the incretin system and DPP-IV on the other hand, could represent a therapeutic route of fundamental importance to reduce the risk of SARS-CoV-2 infection or of severe complications caused by infection.

Does Virus-Receptor Interplay Influence Human Coronaviruses Infection Outcome?

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the third (following SARS-CoV and Middle East Respiratory Syndrome-CoV) zoonotic coronavirus that has crossed the species barrier in the 21st century, resulting in the development of serious human infection. The punishing effect of the recent outbreak of pandemic disease termed COVID-19 (coronavirus disease-19) caused by SARS-CoV-2 impelled us to gather the facts about the nature of coronaviruses. First, we introduce the basic information about coronavirus taxonomy, structure, and replication process to create the basis for more advanced consideration. In the following part of this review, we focused on interactions between the virus and the receptor on the host cell, as this stage is the critical process determining the species and tissue tropism, as well as clinical course of infection. We also illuminate the molecular basis of the strategy used by coronaviruses to cross the species barrier. We give special attention to the cellular receptor's interaction with S protein of different CoVs (dipeptidyl peptidase IV and angiotensin-converting enzyme 2), as well as the cellular proteases involved in proteolysis of this protein. These factors determine the virus entry and replication; thus, even fine quantitative or qualitative differences in their expression may crucially affect outcomes of infection. Understanding virus biology and characterization of the host factors involved in coronavirus transmission and pathogenesis may offer novel options for development of efficient therapeutic and preventive strategies.

The role of Dipeptidyl Peptidase-4 in cutaneous disease

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

COVID-19 and the liver

The current coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a major public health crisis over the past few months. Overall case fatality rates range between 2-6%; however, the rates are higher in the elderly and those with underlying comorbidities like diabetes, hypertension and heart disease. Recent reports showed that about 2-11% of patients with COVID-19 had underlying chronic liver disease. During the previous SARS epidemic, around 60% of patients were reported to develop various degrees of liver damage. In the current pandemic, hepatic dysfunction has been seen in 14-53% of patients with COVID-19, particularly in those with severe disease. Cases of acute liver injury have been reported and are associated with higher mortality. Hepatic involvement in COVID-19 could be related to the direct cytopathic effect of the virus, an uncontrolled immune reaction, sepsis or drug-induced liver injury. The postulated mechanism of viral entry is through the host angiotensin-converting enzyme 2 (ACE2) receptors that are abundantly present in type 2 alveolar cells. Interestingly, ACE2 receptors are expressed in the gastrointestinal tract, vascular endothelium and cholangiocytes of the liver. The effects of COVID-19 on underlying chronic liver disease require detailed evaluation and, with data currently lacking, further research is warranted in this area.

Expression profiles of the SARS-CoV-2 host invasion genes in nasopharyngeal and oropharyngeal swabs of COVID-19 patients

We collect the nasopharyngeal and oropharyngeal swabs of 63 subjects with severe symptoms or contacts with COVID-19 confirmed cases to perform a pilot-study aimed to verify the “in situ” expression of SARS-CoV-2 host invasion genes (ACE2, TMPRSS2, PCSK3, EMILIN1, EMILIN2, MMRN1, MMRN2, DPP4). ACE2 (FC = +1.88, p ≤ 0.05) and DPP4 (FC = +3, p < 0.01) genes showed a significant overexpression in COVID-19 patients. ACE2 and DPP4 expression levels had a good performance (AUC = 0.75; p < 0.001) in distinguishing COVID-19 patients from negative subjects. Interestingly, we found a significant positive association of ACE2 mRNA and PCSK3, EMILIN1, MMRN1 and MMRN2 expression and of DPP4 mRNA and EMILIN2 expression only in COVID-19 patients. Noteworthy, a subgroup of severe COVID-19 (n = 7) patients, showed significant high level of ACE2 mRNA and another subgroup of less severe COVID-19 patients (n = 6) significant raised DPP4 levels.

These results indicate that a group of SARS-CoV-2 host invasion genes are functionally related in COVID-19 patients and suggests that ACE2 and DPP4 expression level could act as genomic biomarkers. Moreover, at the best of our knowledge, this is the first study that shows an elevated DPP4 expression in naso- and oropharyngeal swabs of COVID-19 patient thus suggesting a functional role of DPP4 in SARS-CoV-2 infections.

An Introduction to SARS Coronavirus 2; Comparative Analysis with MERS and SARS Coronaviruses: A Brief Review

Since the 1970 the replication and pathogenesis mechanism of different coronaviruses have been studded.. In 2002-2003, SARS (Severe Acute Respiratory Syndrome coronavirus) in China emerged which resulted in 8098 cases and 774 deaths. About 10 years later in 2012, the MERS (Middle East Respiratory Syndrome coronavirus) spread in Middle Eastern countries and leads to infection in 2465 cases. In Dec 2019, another acute respiratory disease caused by a novel coronavirus named SARS-2 emerged in Wuhan, China. The virus is assumed to be mainly transmitted by respiratory droplets. Travels and communications leads to high prevalence of COVID-19 (Coronavirus Disease 2019) in the world, and currently in Iran. The current review was conducted to compare the virus structure, genome organization, virus life cycle, pathogenesis and prediction the future of COVID-19.

Neurological consequences of COVID-19: what have we learned and where do we go from here?

The coronavirus disease-19 (COVID-19) pandemic is an unprecedented worldwide health crisis. COVID-19 is caused by SARS-CoV-2, a highly infectious pathogen that is genetically similar to SARS-CoV. Similar to other recent coronavirus outbreaks, including SARS and MERS, SARS-CoV-2 infected patients typically present with fever, dry cough, fatigue, and lower respiratory system dysfunction, including high rates of pneumonia and acute respiratory distress syndrome (ARDS); however, a rapidly accumulating set of clinical studies revealed atypical symptoms of COVID-19 that involve neurological signs, including headaches, anosmia, nausea, dysgeusia, damage to respiratory centers, and cerebral infarction. These unexpected findings may provide important clues regarding the pathological sequela of SARS-CoV-2 infection. Moreover, no efficacious therapies or vaccines are currently available, complicating the clinical management of COVID-19 patients and emphasizing the public health need for controlled, hypothesis-driven experimental studies to provide a framework for therapeutic development. In this mini-review, we summarize the current body of literature regarding the central nervous system (CNS) effects of SARS-CoV-2 and discuss several potential targets for therapeutic development to reduce neurological consequences in COVID-19 patients.

An overview of Middle East respiratory syndrome coronavirus vaccines in preclinical studies

INTRODUCTION

Middle East respiratory syndrome coronavirus (MERS-CoV) causes high mortality in humans. No vaccines are approved for use in humans; therefore, a consistent effort to develop safe and effective MERS vaccines is needed.

AREAS COVERED

This review describes the structure of MERS-CoV and the function of its proteins, summarizes MERS vaccine candidates under preclinical study (based on spike and non-spike structural proteins, inactivated virus, and live-attenuated virus), and highlights potential problems that could prevent these vaccines entering clinical trials. It provides guidance for the development of safe and effective MERS-CoV vaccines.

EXPERT OPINION

Although many MERS-CoV vaccines have been developed, most remain at the preclinical stage. Some vaccines demonstrate immunogenicity and efficacy in animal models, while others have potential adverse effects or low efficacy against high-dose or divergent virus strains. Novel strategies are needed to design safe and effective MERS vaccines to induce broad-spectrum immune responses and improve protective efficacy against multiple strains of MERS-CoV and MERS-like coronaviruses with pandemic potential. More funds should be invested to move vaccine candidates into human clinical trials.

Soluble cluster of differentiation 26/soluble dipeptidyl peptidase-4 and glypican-3 are promising serum biomarkers for the early detection of Hepatitis C virus related hepatocellular carcinoma in Egyptians

BACKGROUND AND STUDY AIMS

Many patients are diagnosed with hepatocellular carcinoma (HCC) in the late stage when it is already untreatable. Therefore, there is an increased need for sensitive biomarkers to detect HCC at an earlier stage in high risk patients with hepatitis C virus (HCV)-induced cirrhosis. This study aimed to evaluate the diagnostic performance of soluble cluster of differentiation 26/dipeptidyl peptidase 4 (sCD26/sDPP4) and glypican-3 (GPC3) as serum biomarkers for the early detection of HCV related HCC and compare it with that of the conventional tumor marker serum alpha fetoprotein (AFP).

PATIENTS AND METHODS

The study included 80 participants, 30 patients diagnosed with HCV infection without HCC (HCV group), 30 patients diagnosed with HCV- related HCC (HCV group), and 20 healthy volunteers (control group). The serum levels of GPC3 and sCD26 were measured using specific enzyme linked immunosorbant assay (ELISA) kits, whereas AFP levels were determined using chemiluminescence.

RESULTS

The serum levels of both sCD26 and GPC3 were found to be significantly higher in patients with early-stage HCC than in the HCV group, (1450 and 1.16 ng/mL, respectively). sCD26 at a cutoff value of > 1000 ng/ml, showed a high sensitivity (83.3%) and 63.3% specificity with an area under curve (AUC) of 0.811 and a 95% confidence interval (CI) of (0.682-0.94). While, the combination of GPC3 and sCD26 exhibited the best diagnostic performance for early-stage-HCC because it increased the sensitivity and specificity (85% and 93.3% respectively), with an AUC of 0.986 and a 95% CI of (0.899-1.00) compared to sCD26 alone.

CONCLUSION

We conclude that serum sCD26 could be a sensitive biomarker for the early detection of HCC among HCV patients. Moreover, the combination of sCD26 and GPC3 increases both the sensitivity and specificity for the early detection of HCV related HCC compared with AFP and could help in the monitoring of HCC in high risk patients with HCV induced cirrhosis.

Neuroinvasive potential of a primary respiratory pathogen SARS- CoV2: Summarizing the evidences

BACKROUND AND AIMS

After the emergence of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in the last two decades, the world is facing its new challenge in SARS-CoV-2 pandemic with unfathomable global responses. The characteristic clinical symptoms for Coronavirus (COVID-19) affected patients are high fever, dry-cough, dyspnoea, lethal pneumonia whereas some patients also show additional neurological signs such as headache, nausea, vomiting etc. The accumulative evidences suggest that SARS-CoV-2 is not only confined within the respiratory tract but may also invade the central nervous system (CNS) and peripheral nervous system (PNS) inducing some fatal neurological diseases. Here, we analyze the phylogenetic perspective of SARS-CoV-2 with other strains of β-Coronaviridae from a standpoint of neurological spectrum disorders.

METHODOLOGY

A Pubmed/Medline, NIH Lit Covid, Cochrane library and some open data bases (BioRxiv, MedRxiv,preprint.org and others) search were carried out by using keywords relevant to our topic of discussion. The extracted literatures are scrutinized by the authors.

RESULTS

58 literatures including original articles, case reports and case series were selected by the authors to analyze the differential distribution of neurological impairments in COVID-19 positive patients along with angiotensin-converting enzyme-2 (ACE2) expression dynamics in neuronal and non-neuronal tissue in CNS and PNS with neuroinvasive potential of SARS-CoV2.

CONCLUSION

We discuss the need for modulations in clinical approach from a neurological point of view, as a measure towards reducing disease transmission, morbidity and mortality in SARS-CoV2 positive patients.