Dipeptidyl-peptidase IV from bench to bedside: an update on structural properties, functions, and clinical aspects of the enzyme DPP IV

CD26lowPD-1+ CD8 T cells are terminally exhausted and associated with leukemia progression in acute myeloid leukemia

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Novel effective treatment is an urgent unmet need. Immunotherapy targeting T cell exhaustion by blocking inhibitory pathways, such as PD-1, is promising in cancer treatment. However, results from clinical studies applying PD-1 blockade to AML patients are largely disappointing. AML is highly heterogeneous. Identification of additional immune regulatory pathways and defining predictive biomarkers for treatment response are crucial to optimize the strategy. CD26 is a marker of T cell activation and involved in multiple immune processes. Here, we performed comprehensive phenotypic and functional analyses on the blood samples collected from AML patients and discovered that CD26^lowPD-1⁺ CD8 T cells were associated with AML progression. Specifically, the percentage of this cell fraction was significantly higher in patients with newly diagnosed AML compared to that in patients achieved completed remission or healthy controls. Our subsequent studies on CD26^lowPD-1⁺ CD8 T cells from AML patients at initial diagnosis demonstrated that this cell population highly expressed inhibitory receptors and displayed impaired cytokine production, indicating an exhaustion status. Importantly, CD26^lowPD-1⁺ CD8 T cells carried features of terminal exhaustion, manifested by higher frequency of T_EMRA differentiation, increased expression of transcription factors that are observed in terminally exhausted T cells, and high level of intracellular expression of granzyme B and perforin. Our findings suggest a prognostic and predictive value of CD26 in AML, providing pivotal information to optimize the immunotherapy for this devastating cancer.

Preparation, structural properties, and in vitro and in vivo activities of peptides against dipeptidyl peptidase IV (DPP-IV) and α-glucosidase: a general review

Diabetes is one of the fastest-growing and most widespread diseases worldwide. Approximately 90% of diabetic patients have type 2 diabetes. In 2019, there were about 463 million diabetic patients worldwide. Inhibiting the dipeptidyl peptidase IV (DPP-IV) and α-glucosidase activity is an effective strategy for the treatment of type 2 diabetes. Currently, various anti-diabetic bioactive peptides have been isolated and identified. This review summarizes the preparation methods, structure-effect relationships, molecular binding sites, and effectiveness validation of DPP-IV and α-glucosidase inhibitory peptides in cellular and animal models. The analysis of peptides shows that the DPP-IV inhibitory peptides, containing 2-8 amino acids and having proline, leucine, and valine at their N-terminal and C-terminal, are the highly active peptides. The more active α-glucosidase inhibitory peptides contain 2-9 amino acids and have valine, isoleucine, and proline at the N-terminal and proline, alanine, and serine at the C-terminal.

Chemical and biological characterization of the DPP-IV inhibitory activity exerted by lupin (Lupinus angustifolius) peptides: From the bench to the bedside investigation

Dipeptidyl peptidase IV (DPP-IV) is considered a key target for the diabetes treatment, since it is involved in glucose metabolism. Although lupin protein consumption shown hypoglycemic activity, there is no evidence of its effect on DPP-IV activity. This study demonstrates that a lupin protein hydrolysate (LPH), obtained by hydrolysis with Alcalase, exerts anti-diabetic activity by modulating DPP-IV activity. In fact, LPH decreased DPP-IV activity in a cell-free and cell-based system. Contextually, Caco-2 cells were employed to identify LPH peptides that can be intestinally trans-epithelial transported. Notably, 141 different intestinally transported LPH sequences were identified using nano- and ultra-chromatography coupled to mass spectrometry. Hence, it was demonstrated that LPH modulated the glycemic response and the glucose concentration in mice, by inhibiting the DPP-IV. Finally, a beverage containing 1 g of LPH decreased DPP-IV activity and glucose levels in humans.

Role of obesity related inflammation in pathogenesis of peripheral artery disease in patients of type 2 diabetes mellitus

Objective

Type 2 diabetes mellitus (T2DM) has emerged as one of the greatest global health challenges of twenty-first century. Visceral obesity is one of the most important determinant of insulin resistance (IR) as well as T2DM complications. Therefore this review focuses on the molecular mechanism of obesity induced inflammation, signaling pathways contributing to diabetes, as well as role of lifestyle interventions and medical therapies in the prevention and management of T2DM.

Method

Articles were searched on digital data base PubMed, Cochrane Library, and Web of Science. The key words used for search included Type 2 diabetes mellitus, obesity, insulin resistance, vascular inflammation and peripheral arterial disease.

Result

Visceral obesity is associated with chronic low grade inflammation and activation of immune systems which are involved in pathogenesis of obesity related IR and T2DM.

Conclusion

Metabolic dysregulation of adipose tissue leads to local hypoxia, misfolded/unfolded protein response and increased circulating free fatty acids, which in turn initiate inflammatory signaling cascades in the population of infiltrating cells. Mechanism that relates the role of adipocytokines with insulin sensitivity and glucose homeostasis might throw a light on the development of therapeutic interventions and subsequently might result in the reduction of vascular complications.

DPP-4 inhibitors for treating T2DM - hype or hope? an analysis based on the current literature

DPP-4 inhibition is an interesting line of therapy for treating Type 2 Diabetes Mellitus (T2DM) and is based on promoting the incretin effect. Here, the authors have presented a brief appraisal of DPP-4 inhibitors, their modes of action, and the clinical efficiency of currently available drugs based on DPP-4 inhibitors. The safety profiles as well as future directions including their potential application in improving COVID-19 patient outcomes have also been discussed in detail. This review also highlights the existing queries and evidence gaps in DPP-4 inhibitor research. Authors have concluded that the excitement surrounding DPP-4 inhibitors is justified because in addition to controlling blood glucose level, they are good at managing risk factors associated with diabetes.

Purification and characterization of the dipeptidyl peptidase-IV inhibitory peptides from eel (Anguilla rostrata) scraps enzymatic hydrolysate for the treatment of type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a serious threat to human health. Owing to the action of dipeptidyl peptidase-IV (DPP-IV), the half-life of entero-insulin hormone after secretion is extremely short, causing insufficient insulin secretion in diabetic patients. Dipeptidyl peptidase-IV inhibitors can be used as a new treatment for T2DM. In this study, the proteins of eel (Anguilla rostrata) scraps hydrolyzed using Protamex protease (EPHs) were found to have strong DPP-IV inhibitory activity. The study also provided research ideas for the development and utilization of A. rostrata scraps.

RESULTS

The median inhibition concentration (IC₅₀ ) value of EPHs was 5.455 ± 0.24 mg mL^-1 . The peptide fractions with the highest DPP-IV inhibitory activity were sequentially separated by ultrafiltration, gel filtration chromatography (GFC), and reversed-phase high performance liquid chromatography (RP-HPLC) in a continuous hierarchical manner and analyzed using matrix-assisted laser desorption/ionization time-of-flight/ time-of-flight mass spectrometry/mass spectrometry (MALDI-TOF/TOF MS/MS). Three peptides that revealed significant inhibitory activity were screened among the identified sequences, with sequences of Phe-Pro-Arg (IC₅₀  = 62.14 ± 1.47 μM), Tyr-Pro-Pro-Ser-Phe-Ser (IC₅₀  = 102.65 ± 4.57 μM), and Tyr-Pro-Tyr-Pro-Ala-Ser (IC₅₀  = 68.30 ± 3.85 μM). Molecular docking simulations revealed that their inhibitory effect was mainly due to the formation of hydrogen bonds with amino acid residues in the active sites of DPP-IV. Analysis of the inhibition patterns of the synthetic peptides displayed that Phe-Pro-Arg and Tyr-Pro-Pro-Ser-Phe-Ser displayed competitive inhibition, whereas Tyr-Pro-Tyr-Pro-Ala-Ser showed mixed competitive/non-competitive inhibition.

CONCLUSIONS

The protein hydrolysates isolated from eel scraps are potential functional food ingredients for the treatment of T2DM. © 2023 Society of Chemical Industry.

Differential Anti-Tumor Effects of IFN-Inducible Chemokines CXCL9, CXCL10, and CXCL11 on a Mouse Squamous Cell Carcinoma Cell Line

Chemokines are a group of cytokines involved in the mobilization of leukocytes, which play a role in host defense and a variety of pathological conditions, including cancer. Interferon (IFN)-inducible chemokines C-X-C motif ligand 9 (CXCL), CXCL10, and CXCL11 are anti-tumor chemokines; however, the differential anti-tumor effects of IFN-inducible chemokines are not completely understood. In this study, we investigated the anti-tumor effects of IFN-inducible chemokines by transferring chemokine expression vectors into a mouse squamous cell carcinoma cell line, SCCVII, to generate a cell line stably expressing chemokines and transplanted it into nude mice. The results showed that CXCL9- and CXCL11-expressing cells markedly inhibited tumor growth, whereas CXCL10-expressing cells did not inhibit growth. The NH₂-terminal amino acid sequence of mouse CXCL10 contains a cleavage sequence by dipeptidyl peptidase 4 (DPP4), an enzyme that cleaves the peptide chain of chemokines. IHC staining indicated DPP4 expression in the stromal tissue, suggesting CXCL10 inactivation. These results suggest that the anti-tumor effects of IFN-inducible chemokines are affected by the expression of chemokine-cleaving enzymes in tumor tissues.

Diabetes as one of the long-term COVID-19 complications: from the potential reason of more diabetic patients' susceptibility to COVID-19 to the possible caution of future global diabetes tsunami

According to recent researches, people with diabetes mellitus (type 1 and 2) have a higher incidence of coronavirus disease 2019 (COVID-19), which is caused by a SARS-CoV-2 infection. In this regard, COVID-19 may make diabetic patients more sensitive to hyperglycemia by modifying the immunological and inflammatory responses and increasing reactive oxygen species (ROS) predisposing the patients to severe COVID-19 and potentially lethal results. Actually, in addition to COVID-19, diabetic patients have been demonstrated to have abnormally high levels of inflammatory cytokines, increased virus entrance, and decreased immune response. On the other hand, during the severe stage of COVID-19, the SARS-CoV-2-infected patients have lymphopenia and inflammatory cytokine storms that cause damage to several body organs such as β cells of the pancreas which may make them as future diabetic candidates. In this line, the nuclear factor kappa B (NF-κB) pathway, which is activated by a number of mediators, plays a substantial part in cytokine storms through various pathways. In this pathway, some polymorphisms also make the individuals more competent to diabetes via infection with SARS-CoV-2. On the other hand, during hospitalization of SARS-CoV-2-infected patients, the use of some drugs may unintentionally lead to diabetes in the future via increasing inflammation and stress oxidative. Thus, in this review, we will first explain why diabetic patients are more susceptible to COVID-19. Second, we will warn about a future global diabetes tsunami via the SARS-CoV-2 as one of its long-term complications.

Evogliptin, a DPP-4 inhibitor, prevents diabetic cardiomyopathy by alleviating cardiac lipotoxicity in db/db mice

Dipeptidyl peptidase-4 (DPP-4) inhibitors are glucose-lowering drugs for type 2 diabetes mellitus (T2DM). We investigated whether evogliptin® (EVO), a DPP-4 inhibitor, could protect against diabetic cardiomyopathy (DCM) and the underlying mechanisms. Eight-week-old diabetic and obese db/db mice were administered EVO (100 mg/kg/day) daily by oral gavage for 12 weeks. db/db control mice and C57BLKS/J as wild-type (WT) mice received equal amounts of the vehicle. In addition to the hypoglycemic effect, we examined the improvement in cardiac contraction/relaxation ability, cardiac fibrosis, and myocardial hypertrophy by EVO treatment. To identify the mechanisms underlying the improvement in diabetic cardiomyopathy by EVO treatment, its effect on lipotoxicity and the mitochondrial damage caused by lipid droplet accumulation in the myocardium were analyzed. EVO lowered the blood glucose and HbA1c levels and improved insulin sensitivity but did not affect the body weight or blood lipid profile. Cardiac systolic/diastolic function, hypertrophy, and fibrosis were improved in the EVO-treated group. EVO prevented cardiac lipotoxicity by reducing the accumulation of lipid droplets in the myocardium through suppression of CD36, ACSL1, FABP3, PPARgamma, and DGAT1 and enhancement of the phosphorylation of FOXO1, indicating its inhibition. The EVO-mediated improvement in mitochondrial function and reduction in damage were achieved through activation of PGC1a/NRF1/TFAM, which activates mitochondrial biogenesis. RNA-seq results for the whole heart confirmed that EVO treatment mainly affected the differentially expressed genes (DEGs) related to lipid metabolism. Collectively, these findings demonstrate that EVO improves cardiac function by reducing lipotoxicity and mitochondrial injury and provides a potential therapeutic option for DCM.

Inhibition of dipeptidyl peptidase-4 (DPP4), antioxidant, antiglycation and anti-inflammatory effect of Ferulic acid against streptozotocin toxicity mediate nephropathy in diabetic rats

The protein glycation due to high blood glucose mediate release of inflammatory intermediate contributes in the development of diabetic nephropathy. Ferulic acid (FA) is a phenolic compound distributed in different foods as whole grains. Inhibitors of DPP4 improve GLP-1-mediated insulin secretion and inhibit liver gluconeogenesis. This study investigated the impact of FA as anti-inflammatory, antioxidant and antiglycation against streptozotocin-induced diabetic nephropathy in rats. This study was carried out on total ninety male rats allocated into six (each 15 rats); group I (control). All other animals (groups II-VI) were receiving 65 mg/kg STZ for induction of diabetes. Rats in group II (untreated diabetic). Rats in groups III-V were treated with FA (10, 20, 30 mg/kg bw) respectively, i.p. for 8 weeks. Group VI received 10 units insulin daily, sc. Fasting blood samples were subjected for assay of glycated hemoglobin (HA1c), serum MDA, aldose reductase, total antioxidant, DPP4 while kidney tissue subjected for assay of malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), IL-1β and AGEs. Data obtained showed that, FA showed antioxidant activity by reducing MDA and enhancement antioxidant activity compared with untreated rats (p < 0.001) with dose dependence. In addition, FA reduced the activities of aldose reductase, DPP4 (p < 0.001), decreased IL-6, TNF-α and AGEs versus untreated rats (p < 0.001). Histological investigation revealed an improvement in the nephron structure in diabetic rat treated with FA versus untreated group. It was concluded that, FA possesses a potent antioxidant and anti-inflammatory and DPP4 inhibitor. For that, it was considered as a protective agent against the risk of diabetic nephropathy and can be used as alternative or complementary supplement.

DPP-4 Inhibitors as a savior for COVID-19 patients with diabetes

Diabetic patients are at particular risk of severe COVID-19. Human dipeptidyl peptidase-4 (DPP-4) is a membrane-bound aminopeptidase that regulates insulin release by inactivating incretin. DPP-4 inhibitors (DPP-4is) are therefore used as oral anti-diabetic drugs to restore normal insulin levels. These molecules also have anti-inflammatory and anti-hypertension effects. Recent studies on the interactions of SARS-CoV-2 spike glycoprotein and DPP-4 predict a possible entry route for SARS-CoV-2. Therefore, DPP-4is could be effective at reducing the virus-induced 'cytokine storm', thereby ceasing inflammatory injury to vital organs. Moreover, DPP-4is may interfere with viral entry into host cells. Herein, we have reviewed the efficacy of DPP-4is as potential repurposed drugs to reduce the severity of SARS-CoV-2 infection in patients with diabetes.

Insight into the Role of Active Site Protonation States and Water Molecules in the Catalytic Inhibition of DPP4 by Vildagliptin

Vildagliptin (VIL) is an antidiabetic drug that inhibits dipeptidyl peptidase-4 (DPP4) through a covalent mechanism. The molecular bases for this inhibitory process have been addressed experimentally and computationally. Nevertheless, relevant issues remain unknown such as the roles of active site protonation states and conserved water molecules nearby the catalytic center. In this work, molecular dynamics simulations were applied to examine the structures of 12 noncovalent VIL-DPP4 complexes encompassing all possible protonation states of three noncatalytic residues (His126, Asp663, Asp709) that were inconclusively predicted by different computational tools. A catalytically competent complex structure was only achieved in the system with His126 in its ε-form and nonconventional neutral states for Asp663/Asp709. This complex suggested the involvement of one water molecule in the catalytic process of His740/Ser630 activation, which was confirmed by QM/MM simulations. Our findings support the suitability of a novel water-mediated mechanism in which His740/Ser630 activation occurs concertedly with the nucleophilic attack on VIL and the imidate protonation by Tyr547. Then, the restoration of His740/ Tyr547 protonation states occurs via a two-water hydrogen bonding network in a low-barrier process, thus describing the final step of the catalytic cycle for the first time. Additionally, two hydrolytic mechanisms were proposed based on the hydrogen bonding networks formed by water molecules and the catalytic residues along the inhibitory mechanism. These findings are valuable to unveil the molecular features of the covalent inhibition of DPP4 by VIL and support the future development of novel derivatives with improved structural or mechanistic profiles.

Evaluating Khaya senegalensis for Dipeptidyl Peptidase-IV Inhibition Using in Vitro Analysis and Molecular Dynamic Simulation of Identified Bioactive Compounds

The dipeptidyl peptidase-IV (DPP-IV) inhibitory activity of Khaya senegalensis extracts was evaluated. The DPP-IV from a rat kidney was purified to a purification fold of 2.3. Among extracts from K. senegalensis, the hexane extract had the best DPP-IV inhibitory activity, with IC₅₀ value of 1.56±0.61 μg/mL and was fractionated to eleven fractions (A-K). Fraction I had the best DPP-IV inhibition via uncompetitive pattern. GC-MS analysis of fraction I showed that the major bioactive compounds were 3-amino-3-hydroxyimino-N-phenylpropanamide (1) and 11-(2-cyclopenten-1-yl)undecanoic acid (2), with good binding affinities toward DPP-IV, based on molecular docking,. They were then subjected to molecular dynamic simulation using WEBGRO and utilizing a GROMACS system for 100 ns. The 3-amino-3-hydroxyimino-N-phenylpropanamide-DPP-IV complex was more stable and compact than the other complex. K. senegalensis contains compounds like 1 that might be used for the design of new DPP-IV inhibitors.

Deciphering the Kidney Matrisome: Identification and Quantification of Renal Extracellular Matrix Proteins in Healthy Mice

Precise characterization of a tissue's extracellular matrix (ECM) protein composition (matrisome) is essential for biomedicine. However, ECM protein extraction that requires organ-specific optimization is still a major limiting factor in matrisome studies. In particular, the matrisome of mouse kidneys is still understudied, despite mouse models being crucial for renal research. Here, we comprehensively characterized the matrisome of kidneys in healthy C57BL/6 mice using two ECM extraction methods in combination with liquid chromatography tandem mass spectrometry (LC-MS/MS), protein identification, and label-free quantification (LFQ) using MaxQuant. We identified 113 matrisome proteins, including 22 proteins that have not been previously listed in the Matrisome Database. Depending on the extraction approach, the core matrisome (structural proteins) comprised 45% or 73% of kidney ECM proteins, and was dominated by glycoproteins, followed by collagens and proteoglycans. Among matrisome-associated proteins, ECM regulators had the highest LFQ intensities, followed by ECM-affiliated proteins and secreted factors. The identified kidney ECM proteins were primarily involved in cellular, developmental and metabolic processes, as well as in molecular binding and regulation of catalytic and structural molecules' activity. We also performed in silico comparative analysis of the kidney matrisome composition in humans and mice based on publicly available data. These results contribute to the first reference database for the mouse renal matrisome.

Brain Damage in Preterm and Full-Term Neonates: Serum Biomarkers for the Early Diagnosis and Intervention

The Brain is vulnerable to numerous insults that can act in the pre-, peri-, and post-natal period. There is growing evidence that demonstrate how oxidative stress (OS) could represent the final common pathway of all these insults. Fetuses and newborns are particularly vulnerable to OS due to their inability to active the antioxidant defenses. Specific molecules involved in OS could be measured in biologic fluids as early biomarkers of neonatal brain injury with an essential role in neuroprotection. Although S-100B seems to be the most studied biomarker, its use in clinical practice is limited by the complexity of brain damage etiopathogenesis and the time of blood sampling in relation to the brain injury. Reliable early specific serum markers are currently lacking in clinical practice. It is essential to determine if there are specific biomarkers that can help caregivers to monitor the progression of the disease in order to active an early neuroprotective strategy. We aimed to describe, in an educational review, the actual evidence on serum biomarkers for the early identification of newborns at a high risk of neurological diseases. To move the biomarkers from the bench to the bedside, the assays must be not only be of a high sensitivity but suitable for the very rapid processing and return of the results for the clinical practice to act on. For the best prognosis, more studies should focus on the association of these biomarkers to the type and severity of perinatal brain damage.

COVID-19: Diabetes Perspective-Pathophysiology and Management

Recent evidence relating to the impact of COVID-19 on people with diabetes is limited but continues to emerge. COVID-19 pneumonia is a newly identified illness spreading rapidly throughout the world and causes many disabilities and fatal deaths. Over the ensuing 2 years, the indirect effects of the pandemic on healthcare delivery have become prominent, along with the lingering effects of the virus on those directly infected. Diabetes is a commonly identified risk factor that contributes not only to the severity and mortality of COVID-19 patients, but also to the associated complications, including acute respiratory distress syndrome (ARDS) and multi-organ failure. Diabetic patients are highly affected due to increased viral entry into the cells and decreased immunity. Several hypotheses to explain the increased incidence and severity of COVID-19 infection in people with diabetes have been proposed and explained in detail recently. On the other hand, 20-50% of COVID-19 patients reported new-onset hyperglycemia without diabetes and new-onset diabetes, suggesting the two-way interactions between COVID-19 and diabetes. A systematic review is required to confirm diabetes as a complication in those patients diagnosed with COVID-19. Diabetes and diabetes-related complications in COVID-19 patients are primarily due to the acute illness caused during the SARS-CoV-2 infection followed by the release of glucocorticoids, catecholamines, and pro-inflammatory cytokines, which have been shown to drive hyperglycemia positively. This review provides brief insights into the potential mechanisms linking COVID-19 and diabetes, and presents clinical management recommendations for better handling of the disease.

Human Coronavirus Cell Receptors Provide Challenging Therapeutic Targets

Coronaviruses interact with protein or carbohydrate receptors through their spike proteins to infect cells. Even if the known protein receptors for these viruses have no evolutionary relationships, they do share ontological commonalities that the virus might leverage to exacerbate the pathophysiology. ANPEP/CD13, DPP IV/CD26, and ACE2 are the three protein receptors that are known to be exploited by several human coronaviruses. These receptors are moonlighting enzymes involved in several physiological processes such as digestion, metabolism, and blood pressure regulation; moreover, the three proteins are expressed in kidney, intestine, endothelium, and other tissues/cell types. Here, we spot the commonalities between the three enzymes, the physiological functions of the enzymes are outlined, and how blocking either enzyme results in systemic deregulations and multi-organ failures via viral infection or therapeutic interventions is addressed. It can be difficult to pinpoint any coronavirus as the target when creating a medication to fight them, due to the multiple processes that receptors are linked to and their extensive expression.

Linagliptin treatment is associated with altered cobalamin (VitB12) homeostasis in mice and humans

Linagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor used for the treatment of type 2 diabetes, with additional beneficial effects for the kidney. Treatment of mice with linagliptin revealed increased storage of cobalamin (Cbl, Vitamin B12) in organs if a standard Cbl diet (30 µg Cbl/kg chow) is given. In order to translate these findings to humans, we determined methylmalonic acid (MMA), a surrogate marker of functional Cbl homeostasis, in human plasma and urine samples (n = 1092) from baseline and end of trial (6 months after baseline) of the previously completed MARLINA-T2D clinical trial. We found that individuals with medium Cbl levels (MMA between 50 and 270 nmol/L for plasma, 0.4 and 3.5 µmol/mmol creatinine for urine, at baseline and end of trial) exhibited higher MMA values at the end of study in placebo compared with linagliptin. Linagliptin might inhibit the N-terminal degradation of the transcobalamin receptor CD320, which is necessary for uptake of Cbl into endothelial cells. Because we demonstrate that linagliptin led to increased organ levels of Cbl in mice, sustained constant medium MMA levels in humans, and inhibited CD320 processing by DPP-4 in-vitro, we speculate that linagliptin promotes intra-cellular uptake of Cbl by prolonging half-life of CD320.

Encapsulation of Gold-Based Anticancer Agents in Protease-Degradable Peptide Nanofilaments Enhances Their Potency

We investigated the use of amphiphilic, protease-cleavable peptides as encapsulation moieties for hydrophobic metallodrugs, in order to enhance their bioavailability and consequent activity. Two hydrophobic, gold-containing anticancer agents varying in aromatic ligand distribution (Au(I)-N-heterocyclic carbene compounds 1 and 2) were investigated. These were encapsulated into amphiphilic decapeptides that form soluble filamentous structures with hydrophobic cores, varying supramolecular packing arrangements and surface charge. Peptide sequence strongly dictates the supramolecular packing within the aromatic core, which in turn dictates drug loading. Anionic peptide filaments can effectively load 1, and to a lesser extent 2, while their cationic counterparts could not, collectively demonstrating that loading efficiency is dictated by both aromatic and electrostatic (mis)matching between drug and peptide. Peptide nanofilaments were nontoxic to cancerous and noncancerous cells. By contrast, those loaded with 1 and 2 displayed enhanced cytotoxicity in comparison to 1 and 2 alone, when exposed to Caki-1 and MDA-MB-231 cancerous cell lines, while no cytotoxicity was observed in noncancerous lung fibroblasts, IMR-90. We propose that the enhanced in vitro activity results from the enhanced proteolytic activity in the vicinity of the cancer cells, thereby breaking the filaments into drug-bound peptide fragments that are taken up by these cells, resulting in enhanced cytotoxicity toward cancer cells.

Plasma sDPP4 (Soluble Dipeptidyl Peptidase-4) and Cognitive Impairment After Noncardioembolic Acute Ischemic Stroke

BACKGROUND

DPP4 (dipeptidyl peptidase-4) inhibitors have been proven to promote neuronal regeneration, reverse the development of cognitive deficits. However, the association of circulating soluble form (sDPP4 [soluble DPP4]) with poststroke cognitive impairment (PSCI) is unclear. We aimed to investigate the association between plasma sDPP4 levels and PSCI in patients with ischemic stroke.

METHODS

A total of 600 noncardioembolic stroke patients were included based on a preplanned ancillary study from the CATIS (China Antihypertensive Trial in Acute Ischemic Stroke). We used the Montreal Cognitive Assessment to evaluate cognitive function at 3 months follow-up after ischemic stroke. Binary logistic regression analyses were performed to investigate the association of plasma sDPP4 levels with subsequent PSCI. We further calculated integrated discrimination improvement and category-free net reclassification improvement to investigate the incremental prognostic effect of plasma sDPP4 beyond the basic model with conventional risk factors.

RESULTS

Plasma sDPP4 was inversely associated with PSCI after ischemic stroke, and the adjusted odds ratio (95% CI) for the highest versus lowest quartile of sDPP4 was 0.49 (0.29-0.81; P for trend=0.011). Each 1-SD increase of logarithm-transformed plasma sDPP4 concentration was associated with 17% (odds ratio, 0.83 [95% CI, 0.70-0.99]) lower risk of PSCI. Adding plasma sDPP4 to the basic model notably improved risk reclassification for PSCI, as shown by a category-free net reclassification improvement of 19.10% (95% CI, 2.52%-35.68%; P=0.03) and integrated discrimination improvement of 0.79% (95% CI, 0.13%-1.46%; P=0.02).

CONCLUSIONS

Higher plasma sDPP4 levels were associated with decreased risk of cognitive impairment after noncardioembolic ischemic stroke.

Nanofibrous insulin/vildagliptin core-shell PLGA scaffold promotes diabetic wound healing

Introduction: Slow wound repair in diabetes is a serious adverse event that often results in loss of a limb or disability. An advanced and encouraging vehicle is wanted to enhance clinically applicable diabetic wound care. Nanofibrous insulin/vildagliptin core-shell biodegradable poly (lactic-co-glycolic acid) (PLGA) scaffolds to prolong the effective drug delivery of vildagliptin and insulin for the repair of diabetic wounds were prepared. Methods: To fabricate core-shell nanofibrous membranes, vildagliptin mixture with PLGA, and insulin solution were pumped via separate pumps into two differently sized capillary tubes that were coaxially electrospun. Results and Discussion: Nanofibrous core-shell scaffolds slowly released effective vildagliptin and insulin over 2 weeks in vitro migration assay and in vivo wound-healing models. Water contact angle (68.3 ± 8.5° vs. 121.4 ± 2.0°, p = 0.006) and peaked water absorbent capacity (376% ± 9% vs. 283% ± 24%, p = 0.003) of the insulin/vildagliptin core-shell nanofibrous membranes remarkably exceeded those of a control group. The insulin/vildagliptin-loaded core-shell nanofibers improved endothelial progenitor cells migration in vitro (762 ± 77 cells/mm² vs. 424.4 ± 23 cells/mm², p < 0.001), reduced the α-smooth muscle actin content in vivo (0.72 ± 0.23 vs. 2.07 ± 0.37, p < 0.001), and increased diabetic would recovery (1.9 ± 0.3 mm² vs. 8.0 ± 1.4 mm², p = 0.002). Core-shell insulin/vildagliptin-loaded nanofibers extend the drug delivery of insulin and vildagliptin and accelerate the repair of wounds associated with diabetes.

Does a Little Difference Make a Big Difference? Bovine β-Casein A1 and A2 Variants and Human Health-An Update

For over 20 years, bovine beta-casein has been a subject of increasing scientific interest because its genetic A1 variant during gastrointestinal digestion releases opioid-like peptide β-casomorphin-7 (β-CM-7). Since β-CM-7 is involved in the dysregulation of many physiological processes, there is a growing discussion of whether the consumption of the β-casein A1 variant has an influence on human health. In the last decade, the number of papers dealing with this problem has substantially increased. The newest clinical studies on humans showed a negative effect of variant A1 on serum glutathione level, digestive well-being, cognitive performance score in children, and mood score in women. Scientific reports in this field can affect the policies of dairy cattle breeders and the milk industry, leading to the elimination of allele A1 in dairy cattle populations and promoting milk products based on milk from cows with the A2A2 genotype. More scientific proof, especially in well-designed clinical studies, is necessary to determine whether a little difference in the β-casein amino acid sequence negatively affects the health of milk consumers.

Highly pathogenic coronaviruses and the kidney

Since the end of 2019, the outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has triggered a pneumonia epidemic, posing a significant public health challenge in 236 countries, territories, and regions worldwide. Clinically, in addition to the symptoms of pulmonary infection, many patients with SARS-CoV-2 infections, especially those with a critical illness, eventually develop multiple organ failure in which damage to the kidney function is common, ultimately leading to severe consequences such as increased mortality and morbidity. To date, three coronaviruses have set off major global public health security incidents: Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and SARS-CoV-2. Among the diseases caused by the coronaviruses, the coronavirus disease 2019 (COVID-19) has been the most impactful and harmful. Similar to with SARS-CoV-2 infections, previous studies have shown that kidney injury is also common and prominent in patients with the two other highly pathogenic coronaviruses. Therefore, in this review, we aimed to comprehensively summarize the epidemiological and clinical characteristics of these three pandemic-level infections, provide a deep analysis of the potential mechanism of COVID-19 in various types of kidney diseases, and explore the causes of secondary kidney diseases of SARS-CoV-2, so as to provide a reference for further research and the clinical prevention of kidney damage caused by coronaviruses.

Diet evolution of carnivorous and herbivorous mammals in Laurasiatheria

Background

Laurasiatheria contains taxa with diverse diets, while the molecular basis and evolutionary history underlying their dietary diversification are less clear.

Results

In this study, we used the recently developed molecular phyloecological approach to examine the adaptive evolution of digestive system-related genes across both carnivorous and herbivorous mammals within Laurasiatheria. Our results show an intensified selection of fat and/or protein utilization across all examined carnivorous lineages, which is consistent with their high-protein and high-fat diets. Intriguingly, for herbivorous lineages (ungulates), which have a high-carbohydrate diet, they show a similar selection pattern as that of carnivorous lineages. Our results suggest that for the ungulates, which have a specialized digestive system, the selection intensity of their digestive system-related genes does not necessarily reflect loads of the nutrient components in their diets but appears to be positively related to the loads of the nutrient components that are capable of being directly utilized by the herbivores themselves. Based on these findings, we reconstructed the dietary evolution within Laurasiatheria, and our results reveal the dominant carnivory during the early diversification of Laurasiatheria. In particular, our results suggest that the ancestral bats and the common ancestor of ruminants and cetaceans may be carnivorous as well. We also found evidence of the convergent evolution of one fat utilization-related gene, APOB, across carnivorous taxa.

Conclusions

Our molecular phyloecological results suggest that digestive system-related genes can be used to determine the molecular basis of diet differentiations and to reconstruct ancestral diets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-022-02033-6.

Dipeptidyl peptidase 4 inhibitors in COVID-19: Beyond glycemic control

Coronavirus disease 2019 (COVID-19) is associated with a high risk of mortality and complications in patients with diabetes mellitus. Achieving good glycemic control is very important in diabetic patients to reduce complications and mortality due to COVID-19. Recent studies have shown the mortality benefit and anti-inflammatory effects of Dipeptidyl-peptidase-4 inhibitors (DPP-4i) in diabetic patients with COVID-19. DPP-4i may have a beneficial role in halting the severity of infection primarily by three routes, namely viral entry inhibition, anti-inflammatory and anti-fibrotic effects and glycemic control. This has raised the pro-mising hypothesis that DPP-4i might be an optimal strategy for treating COVID-19 in patients with diabetes. This review aims to summarise the possible therapeutic non-glycemic effects of DPP-4i in diabetic patients diagnosed with COVID-19 in the light of available evidence.

Design, synthesis and anti-diabetic activity of piperazine sulphonamide derivatives as dipeptidyl peptidase-4 inhibitors

Type II diabetes (T2DM) is considered one of the most prevalent metabolic disorders in the world. It is known as insulin resistance and persistent hyperglycemia. Over the past decade, inhibition of the enzymatic dipeptidyl peptidase-4 (DPP-4) has indeed been demonstrated to be an efficient and safe intervention for type 2 diabetes. In order to develop innovative DPP-4 inhibitors, several in silico techniques including 3D-QSAR, molecular docking, in-silico toxicity has been performed to confirm a total of 18 novel piperazine and pyridine derivatives to be synthesized from many designed molecules. These molecules have indeed been docked onto the protein surface of the DPP-4 enzyme, and ADMET characteristics have also been generated in silico. The compounds were then developed and analysed using FT-IR. Then, these compounds were investigated for DPP-4 inhibition in vitro. The most promising compound 8h showed 27.32% inhibition at 10μmol L-1 concentration over DPP-4 so selected for further in-vivo anti-diabetic evaluation. Compound 8h decreased blood glucose excursion in a dose-dependent manner during the OGTT and STZ-induced glucose models in normal Albino Wistar rats. Low-dose streptozotocin-induced type 2 diabetes in Albino Wistar rats treated chronically for 21 days with compound 8h resulted in a reduction in serum glucose levels. This highlighted that 8h is a moderately strong and specific blockbuster molecule that can be structurally modified to boost its effectiveness and overall pharmacological profile as a DPP-4 inhibitor.

Distinct Molecular Mechanisms Characterizing Pathogenesis of SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has continued for over 2 years, following the outbreak of coronavirus-19 (COVID-19) in 2019. It has resulted in enormous casualties and severe economic crises. The rapid development of vaccines and therapeutics against SARS-CoV-2 has helped slow the spread. In the meantime, various mutations in the SARS-CoV-2 have emerged to evade current vaccines and therapeutics. A better understanding of SARS-CoV-2 pathogenesis is a prerequisite for developing efficient, advanced vaccines and therapeutics. Since the outbreak of COVID-19, a tremendous amount of research has been conducted to unveil SARSCoV-2 pathogenesis, from clinical observations to biochemical analysis at the molecular level upon viral infection. In this review, we discuss the molecular mechanisms of SARS-CoV-2 propagation and pathogenesis, with an update on recent advances.

Unraveling the interplay between dipeptidyl peptidase 4 and the renin-angiotensin system in heart failure

AIMS

Emerging evidence suggests the existence of a crosstalk between dipeptidyl peptidase 4 (DPP4) and the renin-angiotensin system (RAS). Therefore, combined inhibition of DPP4 and RAS may produce similar pharmacological effects rather than being additive. This study tested the hypothesis that combining an inhibitor of DPP4 with an angiotensin II (Ang II) receptor blocker does not provide additional cardioprotection compared to monotherapy in heart failure (HF) rats.

MAIN METHODS

Male Wistar rats were subjected to left ventricle (LV) radiofrequency ablation or sham operation. Six weeks after surgery, radiofrequency-ablated rats who developed HF were assigned into four groups and received vehicle (water), vildagliptin, valsartan, or both drugs, for four weeks by oral gavage.

KEY FINDINGS

Vildagliptin and valsartan in monotherapy reduced LV hypertrophy, alleviated cardiac interstitial fibrosis, and improved systolic and diastolic function in HF rats, with no additional effect of combination treatment. HF rats displayed higher cardiac and serum DPP4 activity and abundance than sham. Surprisingly, not only vildagliptin but also valsartan in monotherapy downregulated the catalytic function and expression levels of systemic and cardiac DPP4. Moreover, vildagliptin and valsartan alone or in combination comparably upregulate the components of the cardiac ACE2/Ang-(1-7)/MasR while downregulating the ACE/Ang II/AT1R axis.

SIGNIFICANCE

Vildagliptin or valsartan alone is as effective as combined to treat cardiac dysfunction and remodeling in experimental HF. DPP4 inhibition downregulates classic RAS components, and pharmacological RAS blockade downregulates DPP4 in the heart and serum of HF rats. This interplay between DPP4 and RAS may affect HF progression and pharmacotherapy.

Plant-derived bioactive compounds regulate the NLRP3 inflammasome to treat NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a liver disorder characterized by abnormal accumulation of hepatic fat and inflammatory response with complex pathogenesis. Over activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome triggers the secretion of interleukin (IL)-1β and IL-18, induces pyroptosis, and promotes the release of a large number of pro-inflammatory proteins. All of which contribute to the development of NAFLD. There is a great deal of evidence indicating that plant-derived active ingredients are effective and safe for NAFLD management. This review aims to summarize the research progress of 31 active plant-derived components (terpenoids, flavonoids, alkaloids, and phenols) that alleviate lipid deposition, inflammation, and pyroptosis by acting on the NLRP3 inflammasome studied in both in vitro and in vivo NAFLD models. These studies confirmed that the NLRP3 inflammasome and its related genes play a key role in NAFLD amelioration, providing a starting point for further study on the correlation of plant-derived compounds treatment with the NLRP3 inflammasome and NAFLD.

Plasma proteoforms of apolipoproteins C-I and C-II are associated with plasma lipids in the Multi-Ethnic Study of Atherosclerosis

Apolipoproteins (apo) C-I and C-II are key regulators of triglyceride and HDL metabolism. Both exist as full-size native and truncated (apoC-I'; apoC-II') posttranslational proteoforms. However, the determinants and the role of these proteoforms in lipid metabolism are unknown. Here, we measured apoC-I and apoC-II proteoforms by mass spectrometry immunoassay in baseline and 10-year follow-up plasma samples from the Multi-Ethnic Study of Atherosclerosis. We found that baseline total apoC-I (mean = 9.2 mg/dl) was lower in African Americans (AA), Chinese Americans (CA), and Hispanics (by 1.8; 1.0; 1.0 mg/dl vs. whites), higher in women (by 1.2 mg/dl), and positively associated with plasma triglycerides and HDL. Furthermore, we observed that the truncated-to-native apoC-I ratio (apoC-I'/C-I) was lower in CA, negatively associated with triglycerides, and positively associated with HDL. We determined that total apoC-II (8.8 mg/dl) was lower in AA (by 0.8 mg/dl) and higher in CA and Hispanics (by 0.5 and 0.4 mg/dl), positively associated with triglycerides, and negatively associated with HDL. In addition, apoC-II'/C-II was higher in AA and women, negatively associated with triglycerides, and positively associated with HDL. We showed that the change in triglycerides was positively associated with changes in total apoC-I and apoC-II and negatively associated with changes in apoC-I'/C-I and apoC-II'/C-II, whereas the change in HDL was positively associated with changes in total apoC-I and apoC-II'/C-II and negatively associated with change in total apoC-II. This study documents racial/ethnic variation in apoC-I and apoC-II plasma levels and highlights apolipoprotein posttranslational modification as a potential regulator of plasma lipids.

The role of insulin and incretin-based drugs in biliary tract cancer: epidemiological and experimental evidence

Insulin and incretin-based drugs are important antidiabetic agents with complex effects on cell growth and metabolism. Emerging evidence shows that insulin and incretin-based drugs are associated with altered risk of biliary tract cancer (BTC). Observational study reveals that insulin is associated with an increased risk of extrahepatic cholangiocarcinoma (ECC), but not intrahepatic cholangiocarcinoma (ICC) or gallbladder cancer (GBC). This type-specific effect can be partly explained by the cell of origin and heterogeneous genome landscape of the three subtypes of BTC. Similar to insulin, incretin-based drugs also exhibit very interesting contradictions and inconsistencies in response to different cancer phenotypes, including BTC. Both epidemiological and experimental evidence suggests that incretin-based drugs can be a promoter of some cancers and an inhibitor of others. It is now more apparent that this type of drugs has a broader range of physiological effects on the body, including regulation of endoplasmic reticulum stress, autophagy, metabolic reprogramming, and gene expression. In particular, dipeptidyl peptidase-4 inhibitors (DPP-4i) have a more complex effect on cancer due to the multi-functional nature of DPP-4. DPP-4 exerts both catalytic and non-enzymatic functions to regulate metabolic homeostasis, immune reaction, cell migration, and proliferation. In this review, we collate the epidemiological and experimental evidence regarding the effect of these two classes of drugs on BTC to provide valuable information.

Immunoregulation of Ghrelin in neurocognitive sequelae associated with COVID-19: an in silico investigation

Some patients suffering from the new Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) develop an exaggerated inflammatory response triggered by a “cytokine storm” resulting in acute respiratory distress syndrome (ARDS) with the concomitant activation of non-specific inflammatory reactivity in the circulatory system and other organs, leading to multiorgan failure, leaky vasculature, coagulopathies and stroke. Impairment of brain functions may also occur as dysregulations in immune function resulting from neuroendocrine interactions. In this study, we explored, by bioinformatics approaches, the interaction between the multiple inflammatory agents involved in SARS-CoV-2 and Ghrelin (Ghre) together with its receptor GHSR-1A, which are described as anti-inflammatory mediators, in order to investigate what could trigger the hyper-inflammatory response in some SARS-CoV-2 patients. In our analysis, we found several interactions of Ghre and GHSR-1A with SARS-CoV-2 interacting human genes. We observed a correlation between Ghre, angiotensin-converting enzyme 2 ACE2, toll-like receptors 9 (TLR9), and Acidic chitinase (CHIA), whereas its receptor GHSR-1A interacts with chemokine receptor 3 (CXCR3), CCR3, CCR5, CCR7, coagulation factor II (thrombin) receptor-like 1 (F2RL1), vitamin D receptor (VDR), Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) and DDP4 in receptor dipeptidyl peptidase-4. To our knowledge, our findings show, for the first time, that Ghre and GHSR-1A may exert an immunomodulatory function in the course of SARS-Cov-2 infection.

Pharmacovigilance study of the association between dipeptidyl peptidase-4 inhibitors and angioedema using the FDA Adverse Event Reporting System (FAERS)

Dipeptidyl peptidase-4 (DPP-4) plays a minor role in degrading vasoactive peptides that cause angioedema when angiotensin-converting enzyme (ACE) is present and fully functional. This study investigated the association between DPP-4 inhibitors (DPP-4Is) and angioedema, including cases where the concomitant use of ACE inhibitors (ACEIs) was absent. We obtained data from the US Food and Drug Administration Adverse Event Reporting System and performed a disproportionality analysis, using the reporting odds ratio (ROR) and information component (IC) for signal detection in patients aged ≥ 40 years, stratified by age group and sex. No signal was detected for DPP-4Is when the entire dataset was analyzed. However, a signal was detected for the entire female subset group, the three stratified female groups aged ≥ 60 years, and males in their 40 s. After excluding the data of concomitant ACEI users, most ROR and IC values were lower and significant only for females in their 60 s and males aged ≥ 80 years. Regarding individual DPP-4Is signals, those detected for saxagliptin and sitagliptin in some age groups disappeared after excluding the data of ACEI users. Notably, linagliptin was the only DPP-4I where signals were detected in most female groups, regardless of age and without concomitant ACEI use. Our findings suggest that some DPP-4Is were associated with a higher reporting of angioedema as per age and sex, even in the absence of concomitant ACEI use.

Interstitial 2q24.2q24.3 Microdeletion: Two New Cases with Similar Clinical Features with the Exception of Profound Deafness

Interstitial 2q24.2q24.3 microdeletions are rare cytogenetic aberrations associated with heterogeneous clinical features depending on the size of the deletion. Here, we describe 2 patients with overlapping de novo 2q24.2q24.3 deletions, characterized by array-CGH. This is the smallest 2q24.2q24.3 region of overlap described in the literature encompassing only 9 genes (SLC4A10, DPP4, GCG, FAP, IFIH1, GCA, KCNH7, FIGN, GRB14). We focused our attention on SLC4A10, DPP4, and KCNH7, genes associated with neurological features. Our patients presented similar features: intellectual disability, developmental and language delay, hypotonia, joint laxity, and dysmorphic features. Only patient 2 showed profound deafness and also carried a heterozygous mutation of the GJB2 gene responsible for autosomal recessive deafness 1A (DFNB1A: OMIM 220290). Could the disruption of a gene present in the 2q24.2q24.3 deleted region be responsible for her profound hearing loss?

Cardiac Cx43 Signaling Is Enhanced and TGF-β1/SMAD2/3 Suppressed in Response to Cold Acclimation and Modulated by Thyroid Status in Hairless SHRM

The hearts of spontaneously hypertensive rats (SHR) are prone to malignant arrhythmias, mainly due to disorders of electrical coupling protein Cx43 and the extracellular matrix. Cold acclimation may induce cardio-protection, but the underlying mechanisms remain to be elucidated. We aimed to explore whether the adaptation of 9-month-old hairless SHR^M to cold impacts the fundamental cardiac pro-arrhythmia factors, as well as the response to the thyroid status. There were no significant differences in the registered biometric, redox and blood lipids parameters between hairless (SHR^M) and wild type SHR. Prominent findings revealed that myocardial Cx43 and its variant phosphorylated at serine 368 were increased, while an abnormal cardiomyocyte Cx43 distribution was attenuated in hairless SHR^M vs. wild type SHR males and females. Moreover, the level of β-catenin, ensuring mechanoelectrical coupling, was increased as well, while extracellular matrix collagen-1 and hydroxyproline were lower and the TGF-β1 and SMAD2/3 pathway was suppressed in hairless SHR^M males compared to the wild type strain. Of interest, the extracellular matrix remodeling was less pronounced in females of both hypertensive strains. There were no apparent differences in response to the hypothyroid or hyperthyroid status between SHR strains concerning the examined markers. Our findings imply that hairless SHR^M benefit from cold acclimation due to the attenuation of the hypertension-induced adverse downregulation of Cx43 and upregulation of extracellular matrix proteins.

Animal models for COVID-19: advances, gaps and perspectives

COVID-19, caused by SARS-CoV-2, is the most consequential pandemic of this century. Since the outbreak in late 2019, animal models have been playing crucial roles in aiding the rapid development of vaccines/drugs for prevention and therapy, as well as understanding the pathogenesis of SARS-CoV-2 infection and immune responses of hosts. However, the current animal models have some deficits and there is an urgent need for novel models to evaluate the virulence of variants of concerns (VOC), antibody-dependent enhancement (ADE), and various comorbidities of COVID-19. This review summarizes the clinical features of COVID-19 in different populations, and the characteristics of the major animal models of SARS-CoV-2, including those naturally susceptible animals, such as non-human primates, Syrian hamster, ferret, minks, poultry, livestock, and mouse models sensitized by genetically modified, AAV/adenoviral transduced, mouse-adapted strain of SARS-CoV-2, and by engraftment of human tissues or cells. Since understanding the host receptors and proteases is essential for designing advanced genetically modified animal models, successful studies on receptors and proteases are also reviewed. Several improved alternatives for future mouse models are proposed, including the reselection of alternative receptor genes or multiple gene combinations, the use of transgenic or knock-in method, and different strains for establishing the next generation of genetically modified mice.

Assessment of serum dipeptidyl peptidase-IV levels in autoimmune thyroid disease

OBJECTIVE

Decreased serum dipeptidyl peptidase-IV (sDPPIV) levels have been reported in patients with autoimmune diseases. However, few studies have analyzed the association between sDPPIV levels and autoimmune thyroid disease (AITD). This study aimed to evaluate the association between sDPPIV levels and three types of AITD: Graves' disease (GD), Graves' ophthalmopathy (GO), and Hashimoto's thyroiditis (HT).

METHODS

Patients newly diagnosed with GD (n = 65), GO (n = 22), and HT (n = 27) and healthy individuals (n = 30) were recruited. Clinical characteristics and thyroid function data were collected. sDPPIV was measured using enzyme-linked immunosorbent assays.

RESULTS

Compared with controls (786.3 ± 46.95), patients with GD and GO had significantly lower sDPPIV levels (662.2 ± 38.81 and 438.4 ± 31.78). Additionally, sDPPIV levels were negatively associated with antithyroid peroxidase antibody (r = -0.20) and antithyroglobulin antibody (r = -0.19), but there was no significant relationship between thyroid hormone and sDPPIV levels. GO cases were divided by proptosis with and without muscle thickening; sDPPIV levels were lower in the muscle thickening group than those in the without muscle thickening group. Logistic regression analysis showed that sDPPIV was negatively correlated with GO and GD.

CONCLUSIONS

sDPPIV concentrations were abnormal in patients with GD and GO, and reduced sDPPIV expression may be involved in the progression of GO and GD.

Mechanisms of COVID-19 Pathogenesis in Diabetes

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, is a global pandemic impacting 254 million people in 190 countries. Comorbidities, particularly cardiovascular disease, diabetes, and hypertension, increase the risk of infection and poor outcomes. SARS-CoV-2 enters host cells through the angiotensin-converting enzyme-2 receptor, generating inflammation and cytokine storm, often resulting in multiorgan failure. The mechanisms and effects of COVID-19 on patients with high-risk diabetes are not yet completely understood. In this review, we discuss the variety of coronaviruses, structure of SARS-CoV-2, mutations in SARS-CoV-2 spike proteins, receptors associated with viral host entry, and disease progression. Furthermore, we focus on possible mechanisms of SARS-CoV-2 in diabetes, leading to inflammation and heart failure. Finally, we discuss existing therapeutic approaches, unanswered questions, and future directions.

Insight into the role of DPP-4 in fibrotic wound healing

Wound healing is a complex and long-term process consisting of hemostasis, inflammation, proliferation, and maturation/remodeling. These four stages overlap and influence each other; they affect wound healing in different ways, and if they do not function perfectly, they may cause scarring, proliferative scarring and keloid formation. A therapeutic target affecting wound healing in multiple ways will help the healing process proceed more effectively. DPP-4/CD26 is a multifunctional dimorphic glycoprotein widely distributed on the surface of a variety of cells, including fibroblasts and keratin-forming cells. It has been found to affect periwound inflammation, re-epithelialization, extracellular matrix secretion and skin fibrosis and is a potential target for promoting wound healing and inhibiting scar formation. After presenting a brief introduction of the wound healing process and DPP-4/CD26, this paper summarizes the effects of DPP-4/CD26 on cells involved in different stages of wound healing and discusses the feasibility of DPP-4/CD26 as a multifunctional target for the treatment of wound healing and inhibition of scar formation.

Proline-specific peptidase activities (DPP4, PRCP, FAP and PREP) in plasma of hospitalized COVID-19 patients

BACKGROUND

COVID-19 patients experience several features of dysregulated immune system observed in sepsis. We previously showed a dysregulation of several proline-selective peptidases such as dipeptidyl peptidase 4 (DPP4), fibroblast activation protein alpha (FAP), prolyl oligopeptidase (PREP) and prolylcarboxypeptidase (PRCP) in sepsis. In this study, we investigated whether these peptidases are similarly dysregulated in hospitalized COVID-19 patients.

METHODS

Fifty-six hospitalized COVID-19 patients and 32 healthy controls were included. Enzymatic activities of DPP4, FAP, PREP and PRCP were measured in samples collected shortly after hospital admission and in longitudinal follow-up samples.

RESULTS

Compared to healthy controls, both DPP4 and FAP activities were significantly lower in COVID-19 patients at hospital admission and FAP activity further decreased significantly in the first week of hospitalization. While PRCP activity remained unchanged, PREP activity was significantly increased in COVID-19 patients at hospitalization and further increased during hospital stay and stayed elevated until the day of discharge.

CONCLUSION

The changes in activities of proline-selective peptidases in plasma are very similar in COVID-19 and septic shock patients. The pronounced decrease in FAP activity deserves further investigation, both from a pathophysiological viewpoint and as its utility as a part of a biomarker panel.

Rapid imaging of lung cancer using a red fluorescent probe to detect dipeptidyl peptidase 4 and puromycin-sensitive aminopeptidase activities

Rapid identification of lung-cancer micro-lesions is becoming increasingly important to improve the outcome of surgery by accurately defining the tumor/normal tissue margins and detecting tiny tumors, especially for patients with low lung function and early-stage cancer. The purpose of this study is to select and validate the best red fluorescent probe for rapid diagnosis of lung cancer by screening a library of 400 red fluorescent probes based on 2-methyl silicon rhodamine (2MeSiR) as the fluorescent scaffold, as well as to identify the target enzymes that activate the selected probe, and to confirm their expression in cancer cells. The selected probe, glutamine-alanine-2-methyl silicon rhodamine (QA-2MeSiR), showed 96.3% sensitivity and 85.2% specificity for visualization of lung cancer in surgically resected specimens within 10 min. In order to further reduce the background fluorescence while retaining the same side-chain structure, we modified QA-2MeSiR to obtain glutamine-alanine-2-methoxy silicon rhodamine (QA-2OMeSiR). This probe rapidly visualized even borderline lesions. Dipeptidyl peptidase 4 and puromycin-sensitive aminopeptidase were identified as enzymes mediating the cleavage and consequent fluorescence activation of QA-2OMeSiR, and it was confirmed that both enzymes are expressed in lung cancer. QA-2OMeSiR is a promising candidate for clinical application.

Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes

The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.

Enhancement of DPP-IV inhibitory activity and the capacity for enabling GLP-1 secretion through RADA16-assisted molecular designed rapeseed peptide nanogels

The potential of pentapeptide IPQVS (RAP1) and octapeptide ELHQEEPL (RAP2) derived from rapeseed napin as natural dipeptidyl-peptidase IV (DPP-IV) inhibitors is promising. The objective was to develop a nanogel strategy to resist the hydrolysis of digestive and intestinal enzymes to enhance the DPP-IV inhibitory activity of RAP1 and RAP2, and stimulate glucagon-like peptide 1 (GLP-1) secretion of RAP2 by a RADA16-assisted molecular design. The linker of double Gly was used in the connection of RADA16 and the functional oligopeptide region (RAP1 and RAP2). Compared to the original oligopeptides, DPP-IV IC₅₀ of the nanogels RADA16-RAP1 and RADA16-RAP2 decreased by 26.43% and 17.46% in Caco-2 cell monolayers, respectively. The results showed that the two nanogel peptides with no toxicity to cells had higher contents of stable β-sheet structures (increased by 5.6-fold and 5.2-fold, respectively) than the original oligopeptides, and a self-assembled fibrous morphology. Rheological results suggested that the nanogels RADA16-RAP1 and RADA16-RAP2 exhibit good rheological properties for potential injectable applications; the storage modulus (G') was 10 times higher than the low modulus (G''). Furthermore, the RAP2 and its RADA16-assisted nanogel peptide at the concentration of 250 μM significantly (P < 0.05) increased the release of GLP-1 by 35.46% through the calcium-sensing receptor pathway in the enteroendocrine STC-1 cells. Hence, the innovative and harmless nanogels with the sequence of RADA16-GG-X_n have the potential for use by oral and injection administration for treating or relieving type 2 diabetes.

Cordycepin: a bioactive metabolite of Cordyceps militaris and polyadenylation inhibitor with therapeutic potential against COVID-19

Spike protein and main proteases of SARS-CoV-2 have been identified as potential therapeutic targets and their inhibition may lead to the reticence of viral entry and replication in the host body. Despite several efforts; till now no specific drugs are available to treat SARS-CoV-2. Considering all these challenges, the main objective of the present study was to establish therapeutic potential of cordycepin against COVID-19 as a conventional therapeutic strategy. In the present study; molecular interaction study was performed to assess potential binding affinity of cordycepin with SARS-CoV-2 target proteins using computational approach. Additionally, network pharmacology was used to understand cordycepin-protein interactions and their associated pathways in human body. Cordycepin is under clinical trial (NCT00709215) and possesses structural similarity with adenosine except that, it lacks a 3' hydroxyl group in its ribose moiety and hence it served as a poly(A) polymerase inhibitor and terminate premature protein synthesis. Additionally, it is known that functional RNAs of SARS-CoV-2 genome are highly 3'-plyadenylated and leading to synthesis of all viral proteins and if cordycepin can destabilize SARS-CoV-2 RNAs by inhibiting polyadenylation process then it may step forward in terms of inhibition of viral replication and multiplication in the host. Moreover, cordycepin showed strong binding affinity with SARS-CoV-2 spike protein (-145.3) and main proteases (-180.5) that further corroborate therapeutic potential against COVID-19. Since cordycepin has both pre-clinical and clinical information about antiviral activities, therefore; it is suggested to the world community to undertake repurposing cordycepin to test efficacy and safety for the treatment of COVID-19.

SARS-CoV-2: An Overview of the Genetic Profile and Vaccine Effectiveness of the Five Variants of Concern

With the onset of the COVID-19 pandemic, enormous efforts have been made to understand the genus SARS-CoV-2. Due to the high rate of global transmission, mutations in the viral genome were inevitable. A full understanding of the viral genome and its possible changes represents one of the crucial aspects of pandemic management. Structural protein S plays an important role in the pathogenicity of SARS-CoV-2, mutations occurring at this level leading to viral forms with increased affinity for ACE2 receptors, higher transmissibility and infectivity, resistance to neutralizing antibodies and immune escape, increasing the risk of infection and disease severity. Thus, five variants of concern are currently being discussed, Alpha, Beta, Gamma, Delta and Omicron. In the present review, a comprehensive summary of the following critical aspects regarding SARS-CoV-2 has been made: (i) the genomic characteristics of SARS-CoV-2; (ii) the pathological mechanism of transmission, penetration into the cell and action on specific receptors; (iii) mutations in the SARS-CoV-2 genome; and (iv) possible implications of mutations in diagnosis, treatment, and vaccination.

Does DPP-IV Inhibition Offer New Avenues for Therapeutic Intervention in Malignant Disease?

Simple Summary

There is growing interest in identifying the effects of antidiabetic agents on cancer risk, progression, and anti-cancer treatment due to the long-term use of these medications and the inherently increased risk of malignancies in diabetic patients. Tumor development and progression are affected by multiple mediators in the tumor microenvironment, several of which may be proteolytically modified by the multifunctional protease dipeptidyl peptidase-IV (DPP-IV, CD26). Currently, low-molecular-weight DPP-IV inhibitors (gliptins) are used in patients with type 2 diabetes based on the observation that DPP-IV inhibition enhances insulin secretion by increasing the bioavailability of incretins. However, the DPP-IV-mediated cleavage of other biopeptides and chemokines is also prevented by gliptins. The potential utility of gliptins in other areas of medicine, including cancer, is therefore being evaluated. Here, we critically review the existing evidence on the role of DPP-IV inhibitors in cancer pathogenesis, their potential to be used in anti-cancer treatment, and the possible perils associated with this approach.

Abstract

Dipeptidyl peptidase IV (DPP-IV, CD26) is frequently dysregulated in cancer and plays an important role in regulating multiple bioactive peptides with the potential to influence cancer progression and the recruitment of immune cells. Therefore, it represents a potential contributing factor to cancer pathogenesis and an attractive therapeutic target. Specific DPP-IV inhibitors (gliptins) are currently used in patients with type 2 diabetes mellitus to promote insulin secretion by prolonging the activity of the incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Nevertheless, the modulation of the bioavailability and function of other DPP-IV substrates, including chemokines, raises the possibility that the use of these orally administered drugs with favorable side-effect profiles might be extended beyond the treatment of hyperglycemia. In this review, we critically examine the possible utilization of DPP-IV inhibition in cancer prevention and various aspects of cancer treatment and discuss the potential perils associated with the inhibition of DPP-IV in cancer. The current literature is summarized regarding the possible chemopreventive and cytotoxic effects of gliptins and their potential utility in modulating the anti-tumor immune response, enhancing hematopoietic stem cell transplantation, preventing acute graft-versus-host disease, and alleviating the side-effects of conventional anti-tumor treatments.

The Impact of Cardiovascular Risk Factors on the Course of COVID-19

AIM OF THE STUDY

The aim of our review is to indicate and discuss the impact of cardiovascular risk factors, such as obesity, diabetes, lipid profile, hypertension and smoking on the course and mortality of COVID-19 infection.

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is spreading around the world and becoming a major public health crisis. All coronaviruses are known to affect the cardiovascular system. There is a strong correlation between cardiovascular risk factors and severe clinical complications, including death in COVID-19 patients. All the above-mentioned risk factors are widespread and constitute a significant worldwide health problem. Some of them are modifiable and the awareness of their connection with the COVID-19 progress may have a crucial impact on the current and possible upcoming infection.

DATA COLLECTION

We searched for research papers describing the impact of selected cardiovascular risk factors on the course, severity, complications and mortality of COVID-19 infection form PubMed and Google Scholar databases. Using terms, for example: "COVID-19 cardiovascular disease mortality", "COVID-19 hypertension/diabetes mellitus/obesity/dyslipidemia", "cardiovascular risk factors COVID-19 mortality" and other related terms listed in each subtitle. The publications were selected according to the time of their publications between January 2020 and December 2021. From the PubMed database we obtain 1552 results. Further studies were sought by manually searching reference lists of the relevant articles. Relevant articles were selected based on their title, abstract or full text. Articles were excluded if they were clearly related to another subject matter or were not published in English. The types of articles are mainly randomized controlled trial and systematic review. An additional criterion used by researchers was co-morbidities and age of patients in study groups. From a review of the publications, 105 of them were selected for this work with all subheadings included. Findings and Results: The intention of this review was to summarize current knowledge about comorbidities and development of COVID-19 infection. We tried to focus on the course and mortality of the abovementioned virus disease in patients with concomitant CV risk factors. Unfortunately, we were unable to assess the quality of data in screened papers and studies we choose because of the heterogenicity of the groups. The conducted studies had different endpoints and included different groups of patients in terms of nationality, age, race and clinical status. We decide to divide the main subjects of the research into separately described subtitles such as obesity, lipid profile, hypertension, diabetes, smoking. We believe that the studies we included and gathered are very interesting and show modern and present-day clinical data and approaches to COVID-19 infection in specific divisions of patients.