Peptidase Inhibitors Research Articles

Influence of type-4 dipeptidyl peptidase inhibition on endothelium-dependent relaxation of aortae from a db/db mouse model of type 2 diabetes: a comparison with the effect of glimepiride.

PurposeThe aim of this study was to investigate the effects of the type-4 dipeptidyl peptidase (DPP-4) inhibitors linagliptin and vildagliptin as well as the sulfonylurea glimepiride on endothelium-dependent relaxation of aortae from female db/db mice with established hyperglycemia to determine whether these treatments were able to attenuate diabetes-induced endothelial dysfunction.Materials and methodsThe mice were treated with glimepiride (2 mg/kg po per day, weeks 1–6, n=12), glimepiride plus vildagliptin (glimepiride 2 mg/kg po per day, weeks 1–6; vildagliptin 3 mg/kg po per day, weeks 4–6, n=11), glimepiride plus linagliptin (glimepiride 2 mg/kg po per day, weeks 1–6; linagliptin 3 mg/kg po per day, weeks 4–6, n=11) or linagliptin (3 mg/kg po per day, weeks 1–6, n=12). Endothelium-dependent relaxation using acetylcholine was assessed in the absence and presence of pharmacological tools (TRAM-34 1 μM; apamin 1 μM; N-nitro-L-arginine [L-NNA] 100 μM; 1H-[1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one [ODQ] 10 μM) to distinguish relaxation mediated by nitric oxide (NO).ResultsLinagliptin was associated with a significant improvement in endothelium-dependent relaxation (ACh Rmax; db/db 41±1%, linagliptin 73±6%, p<0.05). The enhanced response was maintained in the presence of TRAM-34+ apamin (ACh Rmax; db/db 23±6%, linagliptin 60±6%, p<0.01), ie, when the endothelium-dependent relaxation was mediated by NO. There was no evidence for a contribution from KCa channel opening to responses under any conditions. Glimepiride had no effect on endothelium-dependent relaxation when given alone (ACh Rmax 38±3%). The addition of linagliptin or vildagliptin to glimepiride did not significantly improve endothelium-dependent relaxation. All treatments caused some decrease in aortic superoxide production but the effect of linagliptin was significantly greater than glimepiride (linagliptin 534±60 relative luminescence unit [RLU], glimepiride 1471±265 RLU, p<0.05).ConclusionLinagliptin is superior to glimepiride in regard to the preservation of endothelium-dependent relaxation in the presence of hyperglycemia and the improvement in endothelial function in response to linagliptin treatment is associated with greater antioxidant activity compared to glimepiride.

Glucose-regulated protein 75 in foodborne disease models induces renal tubular necrosis

The incidence of kidney disease has increased rapidly in recent years. One major possible reason for this increase in nephrosis is from foodborne toxins. Since the mechanism of how foodborne toxins are involved in the process of nephrosis is largely unknown, the current study aims to establish a profile for how one of the major toxin threats, ochratoxin A (OTA), induce differential protein expression. In this proteomic study of rat kidneys, 75 kd glucose-regulated protein (Grp75) expression was found to be sensitized by a low concentration of OTA, but inhibited by high doses. In response to OTA, a decrease in Grp75 expression preceded the inhibition of mitochondrial Lon peptidase 1 (Lonp1). Using Grp75 knockdown cell line, it was shown that the inhibition of Grp75 promoted the secretion of kidney injury molecule 1 (Kim1), and suppressed Lonp1 expression in renal injury. Moreover, the acceleration of renal disease was associated with the consumption of Grp75. Our study suggests that the Grp75 protein may be valuable as both a treatment and biomarker for the foodborne diseases that induce renal tubular necrosis. The findings of this research are beneficial for the establishment of nutritional interventions, and the screening of therapeutic targets, in cases of nephrosis.

Inhibition of dipeptidyl peptidase IV by enzymatic hydrolysates derived from primary and secondary whey of fresh and Oaxaca cheeses

Currently, there is an interest in studying natural inhibitors of dipeptidyl peptidase IV (DPP‐IV) for the treatment of type II diabetes. To look for novel inhibitors, the primary and secondary whey of fresh and Oaxaca cheeses was obtained, and the electrophoretic patterns were determined. Hydrolysis with pepsin and trypsin of primary and secondary whey from fresh and Oaxaca cheeses, respectively, showed DPP‐IV inhibition with values of ~51 and 55%, and also an IC50 of 92.86 μg/mL for Oaxaca cheese‐derived peptides. Data show the potential of whey enzymatic hydrolysates from fresh and Oaxaca cheeses as antidiabetic agents.

Neutrophil elastase promotes Leishmania donovani infection via interferon-β.

Visceral leishmaniasis is a deadly illness caused by Leishmania donovani that provokes liver and spleen inflammation and tissue destruction. In cutaneous leishmaniasis, the protein of L. major, named inhibitor of serine peptidases (ISP) 2, inactivates neutrophil elastase (NE) present at the macrophage surface, resulting in blockade of TLR4 activation, prevention of TNF-α and IFN-β production, and parasite survival. We report poor intracellular growth of L. donovani in macrophages from knockout mice for NE (ela−/−), TLR4, or TLR2. NE and TLR4 colocalized with the parasite in the parasitophorous vacuole. Parasite load in the liver and spleen of ela−/− mice were reduced and accompanied by increased NO and decreased TGF-β production. Expression of ISP2 was not detected in L. donovani, and a transgenic line constitutively expressing ISP2, displayed poor intracellular growth in macrophages and decreased burden in mice. Infected ela−/− macrophages displayed significantly lower IFN-β mRNA than background mice macrophages, and the intracellular growth was fully restored by exogenous IFN-β. We propose that L. donovani utilizes the host NE-TLR machinery to induce IFN-β necessary for parasite survival and growth during early infection. Low or absent expression of parasite ISP2 in L. donovani is necessary to preserve the activation of the NE-TLR pathway.—Dias, B. T., Dias-Teixeira, K. L., Godinho, J. P., Faria, M. S., Calegari-Silva, T., Mukhtar, M. M., Lopes, U. G., Mottram, J. C., Lima, A. P. C. A. Neutrophil elastase promotes Leishmania donovani infection via interferon-β.

Effect of peptidases secreted by the opportunistic pathogen Scedosporium aurantiacum on human epithelial cells.

Peptidases secreted by a clinical high-virulence Scedosporium aurantiacum isolate (strain WM 06.482; CBS 136046) under normoxic and hypoxic conditions were separated via size-exclusion chromatography, and peptidase activities present in each fraction were determined using class-specific substrates. The fractions demonstrating peptidase activity were assessed for their effects on the attachment and viability of A549 human lung epithelial cells in vitro. Of the peptidases detected in the size-exclusion chromatography fractions, the elastase-like peptidase reduced cell viability, the chymotrypsin-like peptidase was associated with cell detachment, and the cysteine peptidases were able to abolish both cell attachment and viability. The loss of cell viability and attachment became more prominent with an increase in the peptidase activity and could also be specifically prevented by addition of class-specific peptidase inhibitors. Our findings indicate that peptidases secreted by S. aurantiacum can breach the human alveolar epithelial cell barrier and, thus, may have a role in the pathobiology of the organism.

Progress towards improving homing and engraftment of hematopoietic stem cells for clinical transplantation.

Hematopoietic cell transplantation (HCT) is a life-saving treatment for a variety of hematological and nonhematological disorders. Successful clinical outcomes after transplantation rely on adequate hematopoietic stem cell (HSC) numbers, and the homing and subsequent short-term and long-term engraftment of these cells in the bone marrow. Enhancing the homing capability of HSCs has the potential for high impact on improving HCT and patient survival. There are a number of ways to enhance HSC engraftment. Neutralizing negative epigenetic regulation by histone deacetylase 5 (HDAC5) increases surface CXCR4 expression and promotes human HSC homing and engraftment in immune-deficient NSG (NOD.Cg-Prkdc IL2rgt/Sz) mice. Short-term treatment of cells with glucocorticoids, pharmacological stabilization of hypoxia-inducible factor (HIF)-1α, increasing membrane lipid raft aggregation, and inhibition of dipeptidyl peptidase 4 (DPP4) facilitates HSC homing and engraftment. Added to these procedures, modulating the mitochondria permeability transition pore (MPTP) to mitigate ambient air-induced extra physiological oxygen stress/shock (EPHOSS) by hypoxic harvest and processing, or using cyclosporine A during air collection increases functional HSC numbers and improves HSC engraftment. A better understanding of the regulation of human HSC homing mediated by various signaling pathways will facilitate development of more efficient means to enhance HCT efficacy.

Specific inhibitors of lysozyme and peptidases inhibit the growth of the rumen protozoan Entodinium caudatum without decreasing feed digestion or fermentation in vitro.

Experiments were designed to determine the effects of different chemical inhibitors of lysozyme and peptidases on rumen protozoa and the associated prokaryotes, and in vitro fermentation using Entodinium caudatum as a model protozoan species. Imidazole (a lysozyme inhibitor), phenylmethylsulphonyl fluoride (PMSF, a serine peptidase inhibitor) and iodoacetamide (IOD, a cysteine peptidase inhibitor) were evaluated in vitro both individually and in two- and three-way combinations using E. caudatum monocultures with respect to their ability to inhibit the protozoan and their effect on feed digestion, fermentation and the microbiota. All the three inhibitors, both individually and in combination, decreased E. caudatum counts (P<0·001), and IOD and its combinations with the other inhibitors significantly (P<0·01) decreased ammonia concentration, with the two- and three-way combinations showing additive effective. Feed digestion was not affected, but fermentation and microbial diversity were affected mostly by PMSF, IOD and their combinatorial treatments potentially due to the overgrowth of Streptococcus luteciae accompanying with the disappearance of host ciliates. Entodinium caudatum depends on lysozyme and peptidase for digestion and utilization of the engulfed microbes and specific inhibition of these enzymes can inhibition E. caudatum without adversely affecting feed digestion or fermentation even though they changed the microbiota composition in the cultures. The peptidase inhibitors may have the potential to be used in controlling rumen protozoa to improve ruminal nitrogen utilization efficiency.

In vivo and in vitro anti-inflammatory and pro-osteogenic effects of citrus cystatin CsinCPI-2

Cystatins are natural inhibitors of cysteine peptidases. Recently, cystatins derived from plants, named phytocystatins, have been extensively studied. Among them, CsinCPI-2 proteins from Citrus sinensis were identified and recombinantly produced by our group. Thus, this study described the recombinant expression, purification, and inhibitory activity of this new phytocystatin against human cathepsins K and B and assessed the anti-inflammatory effect of CsinCPI-2 in vitro in mouse and in vivo in rats. In addition, the pro-osteogenic effect of CsinCPI-2 was investigated in vitro. The inflammatory response of mouse macrophage cells stimulated with P. gingivalis was modulated by CsinCPI-2. The in vitro results showed an inhibitory effect (p < 0.05) on cathepsin K, cathepsin B, IL-1β, and TNF-α gene expression. In addition, CsinCPI-2 significantly inhibited in vivo the activity of TNF-α (p < 0.05) in the blood of rats, previously stimulated by E. coli lipopolysaccharide (LPS). CsinCPI-2 had a pro-osteogenic effect in human dental pulp cells, demonstrated by the increase in alkaline phosphatase (ALP) activity, deposition of mineralized nodules, and the gene expression of the osteogenic markers as bone morphogenetic protein 2 (BMP-2), runt-related transcription factor 2 (Runx-2), ALP, osteocalcin, and bone sialoprotein (BSP). These preliminary studies suggested that CsinCPI-2 has a potential anti-inflammatory, and at the same time, a pro-osteogenic effect. This may lead to new therapies for the control of diseases where inflammation plays a key role, such as periodontal disease and apical periodontitis.

460-P: Treatment with Dipeptidyl Peptidase Inhibitors (DPP-4_Rx) Is Associated with Significant Reduction in Macrovascular Events Independent of Glucose Control

We have observed renal protective effects with DPP-4 inhibitor therapy in a prior study done at the VA. Effects of DPP-4_Rx on cardiovascular morbidity and macrovascular events are disputed. Data from a large cohort of veterans diagnosed with type 2 diabetes mellitus (T2DM) were used to identify patients on DPP-4_Rx and without (control). Groups were matched for age (years), sex, BMI, initial renal function, follow-up time (FU, minimum 365 days). Propensity score matching (PSM) was used to adjust groups with a best odds ratio about 1:1. Groups were compared to determine the effect of DPP-4_Rx on the emergence of new macrovascular events identified by ICD-9 and all-cause mortality. Data were extracted using the Veterans Administration Informatics and Computing Infrastructure (VINCI), and analyzed using SAS. Results were compared using t-tests, frequency tables, Kaplan Meier survival curves, hazard ratios (HR) and p values. Results show that subject with DPP-4 (N=24,763) had baseline variables similar to control. DM control improved with DPP-4_Rx but remained worse than control. A significant reduction in new macrovascular events was seen in DPP-4 group (Table). Mortality from all causes was reduced by 78.1%, but time to death was not changed. We conclude that DPP-4_Rx associates with a significant reduction in frequency of all-cause mortality and macrovascular events independent of glucose control. The reduction of macrovascular events explains in part the improved survival and improvements in renal outcomes we have seen before. Disclosure M. Garcia-Touza: None.

978-P: Ambulatory Glucose Monitoring and Pre-Ramadan Counseling in Patients with Type 2 Diabetes: Results from a Single Center Real-World Study

Background: Change in meal timing and content during Ramadan fasting predisposes patients with type 2 diabetes to adverse glycaemic changes like hypoglycemia. Ambulatory blood glucose monitoring (ABGM) may be a valuable tool for monitoring and prevention of complications. Methods: A single center observational surveillance, conducted during Ramadan, May 2018. ABGM was recorded 7 days before Ramadan and during first 7 days of fasting using the FreeStyle® Libre™. All patients received Ramadan related education and appropriate adjustments to the dosage and timing of medication as per IDF-Ramadan guidelines. Average glucose level and glycaemic variability were compared before and during the fasting period. Results: 59 patients gave consent to ABGM during Ramadan fasting. Their mean age was 51.4 years, duration of diabetes 6.5 years, BMI 28.2 kg/m2, systolic blood pressure 124.2 mm Hg and diastolic blood pressure 79.6 mm Hg. Antidiabetic medication included metformin (100%), sulfonylureas (72.9%), dipeptidyl peptidase inhibitors (83%) and alpha-glucosidase inhibitor (6.8%). Co-morbidities included hypertension (52%), dyslipidemia (44%), neuropathy (33.9%) and hypothyroidism (12%). Mean HbA1c was 7.7%. Average glucose levels noted 7 days before Ramadan was 143.4 mg/dL, which reduced to 126.7mg/dL (p &amp;lt;0.0001) during Ramadan (first 7 days of fast). Mean glycaemic pattern demonstrated that time in target was 55.71% and 59.9% (p&amp;gt;0.05), while the time below target (predicting the probable risk of hypoglycaemia) was 10.2% and 16.6% (p = 0.007) before and during Ramadan respectively. Conclusion: Results from this real world study showed that ABGM could be a guiding tool to adapt the overall diabetes management especially during Ramadan, including patient counselling and education on modification of lifestyle and medications, which has a favorable impact on glycaemic control as well as variability (including probability of hypoglycaemia), during Ramadan. Disclosure S.S. Shaikh: None. S.S. Shaikh: None.

IP-10 contributes to the inhibition of mycobacterial growth in an ex vivo whole blood assay

Interferon-γ inducible protein 10 (IP-10), is a potent chemoattractant that promotes migration of monocytes and activated T-cells to inflammation foci. IP-10 is elevated in serum of patients with chronic hepatitis C virus (HCV) and tuberculosis (TB) infections, although it remains to be determined the contribution of IP-10 in restricting Mycobacterium tuberculosis (Mtb) replication. Here, we investigated the impact of IP-10 on mycobacteria replication using the ex vivo model of human whole-blood (WB) assay. In particular, we compared the levels of IP-10 upon infection with different Mtb clinical strains and species of non-tuberculous mycobacteria (NTM) and evaluated how IP-10 may contain bacterial replication. Interestingly, we observed that the inhibition of the host enzyme dipeptidyl peptidase IV (DPP-IV), which inactivates IP-10 through cleavage of two amino acids at the chemokine N-terminus, restricted mycobacterial persistence in WB, supporting the critical role of full length IP-10 in mediating an anti-Mtb response. Addition of recombinant IP-10 expressed in eukaryotic cells enhanced the anti-mycobacterial activity in WB, although no differences were observed when IP-10 containing different proportions of cleaved and non-cleaved forms of the chemokine were added. Moreover, recombinant IP-10 did not exert a direct anti-mycobacterial effect. Our results underscore the clinical relevance of IP-10 in mycobacteria pathogenesis and support the potential outcomes that may derive by targeting the IP-10/CXCR3 pathway as host directed therapies for the treatment of Mtb or NTM infections.

Sacubitril/Valsartan Augments Postprandial Plasma Concentrations of Active GLP-1 When Combined With Sitagliptin in Men.

Combined inhibition of neprilysin and dipeptidyl peptidase 4 (DPP-4) has been shown to augment plasma concentrations of glucagon-like peptide-1(GLP-1) in animal models, but whether this occurs in humans is unknown. To investigate the effects of inhibition of neprilysin by sacubitril/valsartan alone or in combination with a DPP-4 inhibitor (sitagliptin) on plasma concentrations of GLP-1 in healthy men. Two open-labeled crossover studies were performed in human subjects. General community. Nine and 10 healthy young men were included in study 1 and study 2, respectively. Study participants received a standardized meal (34% carbohydrates, 45% fat, 21% protein; total caloric content, 2106 kJ) combined with a prior dose of either sacubitril/valsartan (194/206 mg) or control in study 1 and in study 2, with a prior dose of sitagliptin (2 ×100 mg, given ∼10 hours apart) either alone or with sacubitril/valsartan (194/206 mg). Plasma concentrations of total and intact GLP-1. Sacubitril/valsartan increased postprandial plasma concentrations of total GLP-1 by 67% [total area under the curve (tAUC)0-240min: 3929 ± 344 vs 2348 ± 181 minutes × pmol/L, P = 0.0023] and increased concentrations of intact GLP-1 plasma concentrations more than sitagliptin alone (tAUC0-240min: 1021 ± 114 vs 660 ± 80 minutes × pmol/L, P = 0.01). Plasma concentrations of glucose, insulin, and GIP were not significantly (P > 0.10) changed upon sacubitril/valsartan treatment. Sacubitril/valsartan combined with a DPP-4 inhibitor led to markedly higher concentrations of intact GLP-1 than DPP-4 inhibition alone, supporting a role for both neprilysin and DPP-4 in the metabolism of GLP-1 in humans, a finding that may have therapeutic implications.

Factors Contributing in Incidence and Diagnosis of Metabolic Syndrome: Updated Mini Review

It has been well-established that obesity is the major contributing factor forthe development of metabolic syndrome (MetS), diabetes, cardiovascular disease and certain types of cancer. According to WHO, 44% increase of diabetes, 23% increase of ischaemic heart disease, and between 7% and 41% increase of certain cancer are due to obesity. The Middle East region is reported to have the highest prevalence of diabetes in adults in the world. In Saudi Arabia, over 35% of the population are obese, and it is estimated that 24% of adult has diabetes including undiagnosed diabetes cases. Obesity and chronic metabolic disease associated obesity impose the heavy financial burden on national healthcare in the Gulf countries as they do in most countries worldwide. Biochemical markers for MetS included changes in trace elements, vitamin D,hormonal (adipokines, leptin, adiponectin, ghrelin), inflammatory mediators (IL-6, TNF-α, IL-10), biochemical markers (Ox-LDL, uric acid) and prothrombic factors (PAI-1). Plasminogen Activator Inhibitor-1 (PAI-1) is the primary of four serine peptidase inhibitors that functions to modulate extracellular matrix remodeling and fibrinolysis. The link between PAI-1 and MetS has been established. This review screening major factors and the association between PAI-1, trace elemnts, vitamin D, obesity hormone and expression of obesity genes for early prediction of MetS for control and management to prevent late complications.

Towards Identifying the Binding Site for 125I‐Angiotensin 1‐7

Angiotensin 1–7 (Ang 1‐7) is a product of the renin‐angiotensin system (RAS) that exhibits central actions to reduce blood pressure and improve baroreflex sensitivity. For more than a decade Mas has been considered the receptor for Ang 1‐7, however, to date, no published studies have characterized Mas receptor radioligand binding in tissue membrane preparations. Our laboratory has demonstrated high affinity (low nanomolar KD) binding of a preparation of 125/127I‐Ang 1‐7 in liver membranes, however, this binding is not pharmacologically specific in that the IC50 of Ang 1‐7 is in the micromolar range and all angiotensin peptides compete for 125/127I‐Ang 1‐7 binding equivalently. 125/127I‐Ang 1‐7 binding to liver, kidney, brain and testes membrane preparations from both rats and mice has also failed to demonstrate a high affinity, pharmacologically specific binding site for 125/127I‐Ang 1‐7. Considering that rapid degradation of Ang 1‐7 could be adversely affecting the binding assay, we tested different peptidase inhibitors (JMV‐390, O‐phenanthroline and a proprietary combination of peptidase inhibitors Biotools®) to prevent degradation of the radioligand. Although we were able to reduce Ang 1‐7 degradation with these inhibitors (~80% preservation), we also reduced the total and specific binding of 125I‐Ang 1‐7. Indeed, competition binding assays for 125I‐Ang‐(1–7) with JMV‐390, O‐phenanthroline and Biotools® showed that 125I‐Ang‐(1–7) and all the inhibitors compete for the same binding site with JMV‐390 having a nanomolar IC50. It is important to note that the radioligand used for receptor binding studies contains an iodine125 on the tyrosine in position four of Ang 1‐7, and may have different characteristics for enzymatic metabolism. To assess this possibility, we determined the metabolism of 127I‐Ang 1‐7 (non‐radioactive iodine isotope) and indeed, the metabolism of Ang 1‐7 and 127I‐Ang 1‐7 in liver appear to differ, with 127I‐Ang 1‐7 being more resistant to metabolism. In addition, competition binding assays showed that 127I‐Ang 1‐7 is ~1000‐fold more potent than Ang 1‐7 in competing for 125I‐Ang 1‐7 binding. In conclusion, our results suggest that 125I‐Ang‐(1–7) may be binding to a peptidase rather than a receptor and the addition of the iodine molecule to the tyrosine in position four attenuates its degradation. Studies are underway to identify this peptidase and determine its potential therapeutic importance as a druggable target.Support or Funding InformationCardiovascular Neuroscience Research Fund 337667 Speth (PI) 03/31/15‐12/31/18 ‐ Nova Southeastern Univ.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Increased cystatin F levels correlate with decreased cytotoxicity of cytotoxic T cells.

BackgroundCystatin F is a protein inhibitor of cysteine peptidases, expressed predominantly in immune cells and localised in endosomal/lysosomal compartments. In cytotoxic immune cells cystatin F inhibits both the major pro-granzyme convertases, cathepsins C and H that activate granzymes, and cathepsin L, that acts as perforin activator. Since perforin and granzymes are crucial molecules for target cell killing by cytotoxic lymphocytes, defects in the activation of either granzymes or perforin can affect their cytotoxic potential.Materials and methodsLevels of cystatin F were assessed by western blot and interactions of cystatin F with cathepsins C, H and L were analysed by immunoprecipitation and confocal microscopy. In TALL-104 cells specific activities of the cathepsins and granzyme B were determined using peptide substrates.ResultsTwo models of reduced T cell cytotoxicity of TALL-104 cell line were established, either by treatment by ionomycin or by immunosuppressive transforming growth factor beta. Reduced cytotoxicity correlated with increased levels of cystatin F and with attenuated activities of cathepsins C, H and L and of granzyme B. Co-localisation of cystatin F and cathepsins C, H and L and interactions between cystatin F and cathepsins C and H were demonstrated.ConclusionsCystatin F is designated as a possible regulator of T cell cytotoxicity, similar to its role in natural killer cells.

The Carboxypeptidase Activity of Cathepsin X is not Controlled by Endogenous Inhibitors

Cysteine cathepsins are peptidases with housekeeping functions that play different specific roles in different tissues. Endogenous peptidase inhibitors, such as cystatins and thyropins are the ultimate way of controlling their activity. It appears, however, that cathepsin X, a monocarboxypeptidase, whose overexpression is associated with several pathological processes, is not under the control of endogenous inhibitors. Inhibitors belonging to various groups inhibit other cathepsins tested, but none decrease the carboxypeptidase activity of cathepsin X. This absence of inhibitor control is another feature that distinguishes cathepsin X from other members of the cysteine peptidases.

Function and mechanisms of enteroendocrine cells and gut hormones in metabolism.

Gut hormones have many key roles in the control of metabolism, as they target diverse tissues involved in the control of intestinal function, insulin secretion, nutrient assimilation and food intake. Produced by scattered cells found along the length of the intestinal epithelium, gut hormones generate signals related to the rate of nutrient absorption, the composition of the luminal milieu and the integrity of the epithelial barrier. Gut hormones already form the basis for existing and developing therapeutics for type 2 diabetes mellitus and obesity, exemplified by the licensed glucagon-like peptide 1 (GLP1) mimetics and dipeptidyl peptidase inhibitors that enhance GLP1 receptor activation. Modulating the release of the endogenous stores of GLP1 and other gut hormones is thought to be a promising strategy to mimic bariatric surgery with its multifaceted beneficial effects on food intake, body weight and blood glucose levels. This Review focuses on the molecular mechanisms underlying the modulation of gut hormone release by food ingestion, obesity and the gut microbiota. Depending on the nature of the stimulus, release of gut hormones involves recruitment of a variety of signalling pathways, including G protein-coupled receptors, nutrient transporters and ion channels, which are targets for future therapeutics for diabetes mellitus and obesity.

The serine peptidase inhibitor TPCK induces several morphophysiological changes in the opportunistic fungal pathogen Candida parapsilosis sensu stricto.

Candida parapsilosis sensu stricto (C. parapsilosis) has emerged as the second/third commonest Candida species isolated from hospitals worldwide. Candida spp. possess numerous virulence attributes, including peptidases that play multiple roles in both physiological and pathological events. So, fungal peptidases are valid targets for new drugs development. With this premise in mind, we have evaluated the effect of serine peptidase inhibitors (SPIs) on both cell biology and virulence aspects of C. parapsilosis. First, five different SPIs, phenylmethylsulfonyl fluoride, benzamidine, 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride, N-α-tosyl-L-lysine chloromethyl ketone hydrochloride, and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) were tested, and TPCK showed the best efficacy to arrest fungal growth. Subsequently, the ability of TPCK to modulate physiopathological processes was investigated. Overall, TPCK was able to (i) inhibit the cell-associated serine peptidase activities, (ii) promote morphometric and ultrastructural alterations, (iii) induce an increase in the intracellular oxidation level, which culminates in a vigorous lipid peroxidation and accumulation of neutral lipids in cytoplasmic inclusions, (iv) modulate the expression/exposition of surface structures, such as mannose/glucose-rich glycoconjugates, N-acetylglucosamine-containing molecules, chitin, polypeptides and surface aspartic peptidases, (v) reduce the adhesion to either polystyrene or glass surfaces as well as to partially disarticulate the mature biofilm, (vi) block the fungal interaction with macrophages, and (vii) protect Galleria mellonella from fungal infection, enhancing larvae survivability. Altogether, these results demonstrated that TPCK induced several changes over fungal biology besides the interference with aspects associated to C. parapsilosis virulence and pathogenesis, which indicates that SPIs could be novel promising therapeutic agents in dealing with candidiasis.

Design, Synthesis and Biological Evaluation of Spiro Cyclohexane-1,2- Quinazoline Derivatives as Potent Dipeptidyl Peptidase IV Inhibitors.

Inhibition of dipeptidyl peptidase IV (DPP-4) is currently one of the most valuable and potential chemotherapeutic regimes for the medication of Type 2 Diabetes Mellitus (T2DM). Based on linagliptin, this study discusses the design, synthesis and biological evaluation of spiro cyclohexane-1,2'-quinazoline scaffold hybridized with various heterocyclic ring systems through different atomic spacers as a highly potent DPP-4 inhibitors. DPP-4 enzyme assay represented that most of the target compounds are 102-103 folds more active than the reference drug linagliptin (IC50: 0.0005-0.0089 nM vs 0.77 nM; respectively). Moreover, in vivo oral hypoglycemic activity assay revealed that most of the tested candidates were more potent than the reference drug, sitagliptin, producing rapid onset with long duration of activity that extends to 24 h. Interestingly, the derivatives 11, 16, 18a and 23 showed evidence of mild cytochrome P450 3A4 (CYP3A4) inhibition (IC50; > 210 µM) and their acute toxicity (LD50) was more than 1.9 gm/kg. Molecular simulation study of the new quinazoline derivatives explained the obtained biological results. Finally, we conclude that our target compounds could be highly beneficial for diabetic patients in the clinic.

Inhibition of dipeptidyl peptidase IV by fexofenadine: Virtual screening study

Inhibition of dipeptidyl peptidase IV by fexofenadine: Virtual screening study