ABSTRACT
Regulators of G protein signaling (RGS) proteins constrain G protein-coupled receptor (GPCR)-mediated and other responses throughout the body primarily, but not exclusively, through their GTPase-activating protein activity. Asthma is a highly prevalent condition characterized by airway hyper-responsiveness (AHR) to environmental stimuli resulting in part from amplified GPCR-mediated airway smooth muscle contraction. Rgs2 or Rgs5 gene deletion in mice enhances AHR and airway smooth muscle contraction, whereas RGS4 KO mice unexpectedly have decreased AHR because of increased production of the bronchodilator prostaglandin E2 (PGE2) by lung epithelial cells. Here, we found that knockin mice harboring Rgs4 alleles encoding a point mutation (N128A) that sharply curtails RGS4 GTPase-activating protein activity had increased AHR, reduced airway PGE2 levels, and augmented GPCR-induced bronchoconstriction compared with either RGS4 KO mice or WT controls. RGS4 interacted with the p85α subunit of PI3K and inhibited PI3K-dependent PGE2 secretion elicited by transforming growth factor beta in airway epithelial cells. Together, these findings suggest that RGS4 affects asthma severity in part by regulating the airway inflammatory milieu in a G protein-independent manner.
Subject(s)
Asthma , RGS Proteins , Animals , Humans , Mice , Asthma/metabolism , Asthma/genetics , Asthma/pathology , Bronchoconstriction/genetics , Dinoprostone/metabolism , Epithelial Cells/metabolism , Epithelial Cells/pathology , GTPase-Activating Proteins/genetics , GTPase-Activating Proteins/metabolism , Mice, Knockout , Phosphatidylinositol 3-Kinases/metabolism , Respiratory Hypersensitivity/metabolism , Respiratory Hypersensitivity/genetics , Respiratory Hypersensitivity/pathology , RGS Proteins/metabolism , RGS Proteins/genetics , Cell LineABSTRACT
BACKGROUND: Clarkson disease (monoclonal gammopathy-associated idiopathic systemic capillary leak syndrome, ISCLS) is a rare idiopathic condition marked by transient, relapsing-remitting episodes of systemic microvascular hyper-permeability, which liberates plasma fluid and macromolecules into the peripheral tissues. This pathology manifests clinically as the abrupt onset of hypotensive shock, hemoconcentration, and hypoalbuminemia. METHODS: We analysed endothelial glycocalyx (eGCX)-related markers in plasma from patients with ISCLS during acute disease flares and convalescence by ELISA and comprehensive proteomic profiling. We evaluated eGCX-related components and gene expression in cultured endothelial cells using RNA-sequencing, real-time PCR, and fluorescence staining. RESULTS: Serum levels of eGCX-related core components including hyaluronic acid (HA) and the core proteoglycan soluble syndecan-1 (sCD138) were elevated at baseline and during acute ISCLS flares. Serial measurements demonstrated that sCD138 levels peaked during the recovery (post-leak) phase of the illness. Proteomic analysis of matched acute and convalescent ISCLS plasma revealed increased abundance of eGCX-related proteins, including glypicans, thrombospondin-1 (TSP-1), and eGCX-degrading enzymes in acute compared to remission plasma. Abundance of endothelial cell damage markers did not differ in acute and baseline plasma. Expression of several eGCX-related genes and surface carbohydrate content in endothelial cells from patients with ISCLS did not differ significantly from that observed in healthy control cells. CONCLUSIONS: eGCX dysfunction, but not endothelial injury, may contribute to clinical symptoms of acute ISCLS. Serum levels of of eGCX components including sCD138 may be measured during acute episodes of ISCLS to monitor clinical status and therapeutic responses.
Subject(s)
Capillary Leak Syndrome , Biomarkers , Capillary Leak Syndrome/diagnosis , Capillary Leak Syndrome/pathology , Capillary Leak Syndrome/therapy , Endothelial Cells/pathology , Glycocalyx , Humans , ProteomicsABSTRACT
BACKGROUND: Allergens elicit host production of mediators acting on G-protein-coupled receptors to regulate airway tone. Among these is prostaglandin E2 (PGE2), which, in addition to its role as a bronchodilator, has anti-inflammatory actions. Some patients with asthma develop bronchospasm after the ingestion of aspirin and other nonsteroidal anti-inflammatory drugs, a disorder termed aspirin-exacerbated respiratory disease. This condition may result in part from abnormal dependence on the bronchoprotective actions of PGE2. OBJECTIVE: We sought to understand the functions of regulator of G protein signaling 4 (RGS4), a cytoplasmic protein expressed in airway smooth muscle and bronchial epithelium that regulates the activity of G-protein-coupled receptors, in asthma. METHODS: We examined RGS4 expression in human lung biopsies by immunohistochemistry. We assessed airways hyperresponsiveness (AHR) and lung inflammation in germline and airway smooth muscle-specific Rgs4-/- mice and in mice treated with an RGS4 antagonist after challenge with Aspergillus fumigatus. We examined the role of RGS4 in nonsteroidal anti-inflammatory drug-associated bronchoconstriction by challenging aspirin-exacerbated respiratory disease-like (ptges1-/-) mice with aspirin. RESULTS: RGS4 expression in respiratory epithelium is increased in subjects with severe asthma. Allergen-induced AHR was unexpectedly diminished in Rgs4-/- mice, a finding associated with increased airway PGE2 levels. RGS4 modulated allergen-induced PGE2 secretion in human bronchial epithelial cells and prostanoid-dependent bronchodilation. The RGS4 antagonist CCG203769 attenuated AHR induced by allergen or aspirin challenge of wild-type or ptges1-/- mice, respectively, in association with increased airway PGE2 levels. CONCLUSIONS: RGS4 may contribute to the development of AHR by reducing airway PGE2 biosynthesis in allergen- and aspirin-induced asthma.
Subject(s)
Aspergillosis/metabolism , Aspergillus fumigatus/immunology , Asthma, Aspirin-Induced/metabolism , Lung/pathology , Muscle, Smooth/metabolism , RGS Proteins/metabolism , Respiratory Mucosa/metabolism , Animals , Bronchial Spasm , Cells, Cultured , Dinoprostone/biosynthesis , Female , Humans , Male , Mice , Mice, Knockout , Muscle, Smooth/pathology , Prostaglandin-E Synthases/genetics , RGS Proteins/genetics , Signal TransductionABSTRACT
Neutrophils are white blood cells that are mobilized to damaged tissues and to sites of pathogen invasion, providing the first line of host defense. Chemokines displayed on the surface of blood vessels promote migration of neutrophils to these sites, and tissue- and pathogen-derived chemoattractant signals, including N-formylmethionylleucylphenylalanine (fMLP), elicit further migration to sites of infection. Although nearly all chemoattractant receptors use heterotrimeric G proteins to transmit signals, many of the mechanisms lying downstream of chemoattractant receptors that either promote or limit neutrophil motility are incompletely defined. Here, we show that regulator of G protein signaling 5 (RGS5), a protein that modulates G protein activity, is expressed in both human and murine neutrophils. We detected significantly more neutrophils in the airways of Rgs5-/- mice than WT counterparts following acute respiratory virus infection and in the peritoneum in response to injection of thioglycollate, a biochemical proinflammatory stimulus. RGS5-deficient neutrophils responded with increased chemotaxis elicited by the chemokines CXC motif chemokine ligand 1 (CXCL1), CXCL2, and CXCL12 but not fMLP. Moreover, adhesion of these cells was increased in the presence of both CXCL2 and fMLP. In summary, our results indicate that RGS5 deficiency increases chemotaxis and adhesion, leading to more efficient neutrophil mobilization to inflamed tissues in mice. These findings suggest that RGS5 expression and activity in neutrophils determine their migrational patterns in the complex microenvironments characteristic of inflamed tissues.
Subject(s)
Chemotactic Factors/metabolism , Chemotaxis , Neutrophils/pathology , RGS Proteins/metabolism , RGS Proteins/physiology , Animals , Cell Adhesion , Cell Movement , Cells, Cultured , Humans , Mice , Mice, Inbred BALB C , Mice, Knockout , N-Formylmethionine Leucyl-Phenylalanine/metabolism , Neutrophils/metabolism , Signal TransductionABSTRACT
OBJECTIVES: To assess whether ad libitum consumption of thiamin-fortified fish sauce over 6 months yields higher erythrocyte thiamin diphosphate concentrations (eTDP) among women of childbearing age and their children aged 12-59 months compared with control sauce containing no thiamin. STUDY DESIGN: In this double-blind, randomized controlled efficacy trial, 276 nonpregnant, nonlactating women (18-45 years of age) and their families in Prey Veng, Cambodia, were randomized to receive 1 of 3 fish sauce formulations: low thiamin concentration (low, 2 g/L), high thiamin concentration (high, 8 g/L), or a control (no thiamin) fish sauce. Baseline (t = 0) and endline (t = 6 months) eTDP were measured with the use of high-performance liquid chromatography with a fluorescence detector. RESULTS: Fish sauce consumption did not differ between treatment groups (P = .19). In intent-to-treat analysis, women's baseline-adjusted endline eTDP (mean; 95% CI) was higher among women in the low (259; 245-274 nmol/L) and high (257; 237-276 nmol/L) groups compared with control (184; 169-198 nmol/L; P < .001); low and high groups did not differ (P = .83). Similarly, children's baseline-adjusted eTDP was higher in the low (259; 246-271 nmol/L) and high (257; 243-270 nmol/L) groups compared with control (213; 202-224 nmol/L; P < .001). CONCLUSION: Fortified fish sauce appears to be an efficacious means of improving biochemical thiamin status in nonpregnant, nonlactating women and their children (1-5 years of age) living in rural Cambodia. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02221063.
Subject(s)
Erythrocytes/metabolism , Fish Products , Food, Fortified , Thiamine/administration & dosage , Adolescent , Adult , Animals , Cambodia , Child , Child, Preschool , Chromatography, Liquid , Double-Blind Method , Female , Humans , Infant , Middle Aged , Nutritional Status , Rural Population , Thiamine/blood , Young AdultABSTRACT
BACKGROUND: Thiamin deficiency in infancy is the underlying cause of beriberi, which can be fatal without rapid treatment. Reports of thiamin deficiency are common in Cambodia; however, population representative data are unavailable. Because B-complex vitamin deficiencies commonly occur in combination, riboflavin was also investigated. OBJECTIVE: We determined the biomarker status of thiamin and riboflavin in women of childbearing age in rural and urban Cambodia. METHODS: We measured thiamin (erythrocyte thiamin diphosphate; TDP) and riboflavin (erythrocyte glutathione reductase activity coefficient; EGRac) status in a representative sample of Cambodian women (aged 20-45 y) in urban Phnom Penh (n = 146) and rural Prey Veng (n = 156), Cambodia, and, for comparison purposes, in a convenience sample of women in urban Vancouver, British Columbia, Canada (n = 49). RESULTS: Thiamin insufficiency (TDP ≤ 90 nmol/L) was common among both urban (39%) and rural (59%) Cambodian women (P < 0.001), whereas <20% of Vancouver women were thiamin insufficient (P < 0.001). The prevalence of suboptimal and deficient riboflavin status (EGRac ≥ 1.3) was 89%, 92%, and 70% among women in Phnom Penh, Prey Veng, and Vancouver, respectively (P < 0.001). CONCLUSIONS: Suboptimal status of both thiamin and riboflavin were common in Cambodian women, with substantially higher rates among women living in rural Prey Veng than in urban Phnom Penh. Strategies may be needed to improve the thiamin and riboflavin status of women in Cambodia. The unexpected finding of high riboflavin inadequacy status in Vancouver women warrants further investigation.
Subject(s)
Nutritional Status , Riboflavin Deficiency/epidemiology , Rural Population , Thiamine Deficiency/epidemiology , Urban Population , Adult , Cambodia/epidemiology , Canada/epidemiology , Cross-Sectional Studies , Erythrocytes/drug effects , Erythrocytes/metabolism , Female , Humans , Middle Aged , Riboflavin/blood , Riboflavin Deficiency/blood , Thiamine/blood , Thiamine Deficiency/blood , Thiamine Pyrophosphate/blood , Young AdultSubject(s)
Coronavirus Infections/complications , Coronavirus Infections/diagnosis , Emergency Service, Hospital , Olfaction Disorders/virology , Pneumonia, Viral/complications , Pneumonia, Viral/diagnosis , Betacoronavirus , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques , Humans , Pandemics , Risk Assessment/methods , SARS-CoV-2ABSTRACT
A growing body of evidence suggests a possible relationship between the consumption of dairy products and the incidence of diabetes. A positive correlation between the early introduction of dairy in infancy and the incidence of type 1 diabetes (T1D) in genetically predisposed infants has been suggested by studies on rodents and humans. However, the lines of evidence supporting this association, including epidemiological studies and the observation of antibodies to bovine serum albumin, ß-casein and bovine insulin in the serum of patients with T1D, are not without controversy. On the other hand, an inverse relationship between the consumption of dairy foods and the development of metabolic syndrome and/or type 2 diabetes (T2D) has been implied by epidemiological studies. Several dairy components, especially milk proteins, are believed to play a role in the beneficial effect of dairy consumption on glucose regulation by modulation of incretin hormones. Other dietary factors have also been associated with the incidence of T1D and T2D, indicating that dairy foods might be only one among many dietary agents possibly implicated in the development of diabetes. The present paper critically reviews the evidence and plausible mechanisms for the putative associations between dairy food consumption and incidence of T1D and T2D.
Subject(s)
Dairy Products/adverse effects , Diabetes Mellitus/etiology , Animals , Diabetes Mellitus/epidemiology , Feeding Behavior , HumansABSTRACT
The inhibition of the enzyme dipeptidyl-peptidase IV (DPP-IV) is an effective pharmacotherapeutic approach for the management of type 2 diabetes. Recent findings have suggested that dietary proteins, including bovine α-lactalbumin, could be precursors of peptides able to inhibit DPP-IV. However, information on the location of active peptide sequences within the proteins is far from being comprehensive. Moreover, the traditional approach to identify bioactive peptides from foods can be tedious and long. Therefore, the objective of this study was to use peptide arrays to screen α-lactalbumin-derived peptides for their interaction with DPP-IV. Deca-peptides spanning the entire α-lactalbumin sequence, with a frame shift of 1 amino acid between successive sequences, were synthesized on cellulose membranes using "SPOT" technology, and their binding to and inhibition of DPP-IV was studied. Among the 114 α-lactalbumin-derived decamers investigated, the peptides 60WCKDDQNPHS69 (αK(i) = 76 µM), 105LAHKALCSEK114 (K(i) = 217 µM) and 110LCSEKLDQWL119 (K(i) = 217 µM) were among the strongest DPP-IV inhibitors. While the SPOT- and traditionally-synthesized peptides showed consistent trends in DPP-IV inhibitory activity, the cellulose-bound peptides' binding behavior was not correlated to their ability to inhibit the enzyme. This research showed, for the first time, that peptide arrays are useful screening tools to identify DPP-IV inhibitory peptides from dietary proteins.
Subject(s)
Dipeptidyl Peptidase 4/metabolism , Dipeptidyl-Peptidase IV Inhibitors/chemistry , Dipeptidyl-Peptidase IV Inhibitors/pharmacology , Lactalbumin/chemistry , Peptides/chemistry , Peptides/pharmacology , Amino Acid Sequence , Cellulose/chemistry , Chemistry Techniques, Synthetic , Drug Discovery , HEK293 Cells , Humans , Molecular Sequence Data , Protein Array AnalysisABSTRACT
The antioxidative properties of Pacific hake hydrolysates and their peptidic fractions varying in molecular size were assessed. Hydrolysates produced by different proteases (Alcalase, bromelain, Flavourzyme, Protamex, Protease A"Amano"2, Protease N"Amano"K, Protin SD NY10, Umamizyme-K, Validase BNP-L, Validase FPexo) generally possessed good metal ion chelating (33-73% at 3mg/ml), DPPH radical scavenging (18-30% at 1mg/ml), ferric ion reducing power (abs700nm 0.36-0.86 at 3 mg/ml) and ABTS radical scavenging (47-85% at 0.067 mg/ml) activity, as well as a good capability to suppress lipid peroxidation in a linoleic acid model system. Peptide size (<1.4 kDa) was important for ABTS radical scavenging activity, whereas specific peptide composition (which depended on the particular protease used) was the governing factor for effective lipid peroxidation. Validase BNP-L was the most promising enzyme for producing Pacific hake hydrolysates with good antioxidative activity in various assays and similar effectiveness as the synthetic antioxidant BHT to inhibit lipid peroxidation.
Subject(s)
Antioxidants/pharmacology , Free Radicals/metabolism , Gadiformes/metabolism , Lipid Peroxidation/drug effects , Peptide Fragments/pharmacology , Peptide Hydrolases/metabolism , Protein Hydrolysates/pharmacology , Animals , Free Radical Scavengers/pharmacology , Gadiformes/growth & development , Oxidation-Reduction , Peptide Fragments/chemistry , Protein Hydrolysates/chemistryABSTRACT
We report the clinical and molecular phenotype of three siblings from one family, who presented with short stature and immunodeficiency and carried uncharacterized variants in RGS10 (c.489_491del:p.E163del and c.G511T:p.A171S). This gene encodes regulator of G protein signaling 10 (RGS10), a member of a large family of GTPase-activating proteins (GAPs) that targets heterotrimeric G proteins to constrain the activity of G protein-coupled receptors, including receptors for chemoattractants. The affected individuals exhibited systemic abnormalities directly related to the RGS10 mutations, including recurrent infections, hypergammaglobulinemia, profoundly reduced lymphocyte chemotaxis, abnormal lymph node architecture, and short stature due to growth hormone deficiency. Although the GAP activity of each RGS10 variant was intact, each protein exhibited aberrant patterns of PKA-mediated phosphorylation and increased cytosolic and cell membrane localization and activity compared to the wild-type protein. We propose that the RGS10 p.E163del and p.A171S mutations lead to mislocalization of the RGS10 protein in the cytosol, thereby resulting in attenuated chemokine signaling. This study suggests that RGS10 is critical for both immune competence and normal hormonal metabolism in humans and that rare RGS10 variants may contribute to distinct systemic genetic disorders.
Subject(s)
Body Height/genetics , Primary Immunodeficiency Diseases/genetics , RGS Proteins , GTP-Binding Proteins , Humans , Mutation , RGS Proteins/genetics , RGS Proteins/metabolism , Receptors, G-Protein-Coupled , Signal Transduction/geneticsABSTRACT
OBJECTIVE: Systemic capillary leak syndrome (SCLS) is a rare disorder that presents with episodes of hypovolemic shock. The extent to which genetic abnormalities contribute to SCLS is unknown. We identified pediatric and adult cohorts with characteristic clinical courses. We sought to describe the clinical characteristics of both cohorts, identify a possible genetic contribution to SCLS, and demonstrate that whole-exome sequencing (WES) may be conducted by critical care providers. DESIGN: Prospective observational study of WES of nine adult and eight pediatric SCLS patients and available unaffected first-degree relatives. SETTING: Tertiary children's hospitals and referral research laboratory. PATIENTS: Children and adults with SCLS. INTERVENTIONS: None. MEASUREMENTS: Patients and available first-degree relatives underwent WES. Data were analyzed for rare homozygous, biallelic, de novo, and heterozygous variants with allelic enrichment and metabolic pathway analyses. MAIN RESULTS: Children with SCLS presented at a younger age with episodes similar to those experienced by adults. All patients and available relatives underwent satisfactory WES. No overlapping gene variants or metabolic pathways were identified across all SCLS patients. Multiple candidate genes with homozygous or biallelic mutations were identified in individual subjects with SCLS. There was no significant enrichment of genes with rare heterozygous variants. CONCLUSIONS: The clinical characteristics of children and adults with SCLS are similar. We did not identify a uniform germline exomic genetic etiology for SCLS. WES identified several candidate genes in individual patients for future research. WES is a viable way for critical care providers to investigate the etiology of diseases with presumed genetic contributions.
Subject(s)
Capillary Leak Syndrome/genetics , Capillary Leak Syndrome/pathology , Exome Sequencing/methods , Adult , Capillary Leak Syndrome/metabolism , Female , Genotype , Heterozygote , Humans , Male , Middle Aged , Models, Biological , Mutation, Missense/genetics , Prospective Studies , Sequence Analysis, DNAABSTRACT
The hallmark features of allergic asthma are type 2 (eosinophilic) inflammation and airways hyperresponsiveness (AHR). Although these features often comanifest in mouse lungs in vivo, we demonstrate in this study that the serine protease Alp1 from the ubiquitous mold and allergen, Aspergillus fumigatus, can induce AHR in mice unable to generate eosinophilic inflammation. Strikingly, Alp1 induced AHR in mice devoid of protease-activated receptor 2/F2 trypsin-like receptor 1 (PAR2/F2RL1), a receptor expressed in lung epithelium that is critical for allergic responses to protease-containing allergens. Instead, using precision-cut lung slices and human airway smooth muscle cells, we demonstrate that Alp1 directly increased contractile force. Taken together, these findings suggest that Alp1 induces bronchoconstriction through mechanisms that are largely independent of allergic inflammation and point to a new target for direct intervention of fungal-associated asthma.
Subject(s)
Aspergillus fumigatus/immunology , Asthma/immunology , Asthma/microbiology , Fungal Proteins/immunology , Serine Endopeptidases/immunology , Allergens/immunology , Animals , Aspergillus fumigatus/enzymology , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/immunology , Bronchoconstriction/drug effects , Bronchoconstriction/immunology , Cells, Cultured , Disease Models, Animal , Gene Knockout Techniques , Humans , Inflammation/immunology , Lung/pathology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Myocytes, Smooth Muscle/immunology , Receptor, PAR-2/genetics , Receptor, PAR-2/immunologyABSTRACT
[This corrects the article DOI: 10.1038/s42003-019-0647-4.].
ABSTRACT
The systemic capillary leak syndrome (SCLS, Clarkson disease) is a disorder of unknown etiology characterized by recurrent episodes of vascular leakage of proteins and fluids into peripheral tissues, resulting in whole-body edema and hypotensive shock. The pathologic mechanisms and genetic basis for SCLS remain elusive. Here we identify an inbred mouse strain, SJL, which recapitulates cardinal features of SCLS, including susceptibility to histamine- and infection-triggered vascular leak. We named this trait "Histamine hypersensitivity" (Hhs/Hhs) and mapped it to Chromosome 6. Hhs is syntenic to the genomic locus most strongly associated with SCLS in humans (3p25.3), revealing that the predisposition to develop vascular hyperpermeability has a strong genetic component conserved between humans and mice and providing a naturally occurring animal model for SCLS. Genetic analysis of Hhs may reveal orthologous candidate genes that contribute not only to SCLS, but also to normal and dysregulated mechanisms underlying vascular barrier function more generally.
Subject(s)
Capillary Leak Syndrome/genetics , Animals , Capillary Leak Syndrome/etiology , Capillary Leak Syndrome/physiopathology , Capillary Permeability/genetics , Capillary Permeability/physiology , Chromosome Mapping , Disease Models, Animal , Female , Genetic Predisposition to Disease , Genome-Wide Association Study , Histamine/physiology , Humans , Influenza A Virus, H3N2 Subtype , Male , Mice , Mice, Congenic , Mice, Inbred Strains , Orthomyxoviridae Infections/complications , Skin/blood supply , Species Specificity , SyntenyABSTRACT
BACKGROUND: Various methodologies have been employed for the therapeutic interpolation of the progressive brain disorder Alzheimer's disease. Thus, ß-secretase inhibition is significant to prevent disease progression in the early stages. OBJECTIVE: This study seeks to purify and characterize a novel ß-secretase inhibitory peptide from Pacific hake enzymatic hydrolysate. METHODS: A potent ß-secretase inhibitory peptide was isolated by sequential purifications using Sephadex G-25 column chromatography and octadecylsilane (ODS) C18 reversed-phase HPLC. A total of seven peptides were synthesized using the isolated peptide sequences. SH-SY5Y cells stably transfected with the human ''Swedish'' amyloid precursor protein (APP) mutation APP695 (SH-SY5YAPP695swe) were used as an in-vitro model system to investigate the effect of Leu-Asn peptide on APP processing. RESULTS: The ß-secretase inhibitory activity (IC50) of the purified peptide (Ser-Leu-Ala-Phe-Val-Asp- Asp-Val-Leu-Asn) from fish protein hydrolysate was 18.65 µM and dipeptide Leu-Asn was the most potent ß-secretase inhibitor (IC50 value = 8.82 µM). When comparing all the seven peptides, the inhibition pattern of Leu-Asn dipeptide was found to be competitive by Lineweaver-Burk plot and Dixon plot (Ki value = 4.24 µM). The 24 h treatment with Leu-Asn peptide in SH-SY5Y cells resulted in reducing the ß-amyloid (Aß) production in a dose-dependent manner. CONCLUSION: Therefore, the results of this study suggest that ß-secretase inhibitory peptides derived from marine organisms could be potential candidates to develop nutraceuticals or pharmaceuticals as antidementia agents.
Subject(s)
Amyloid beta-Protein Precursor/drug effects , Fish Proteins/pharmacology , Gadiformes , Neuroprotective Agents/pharmacology , Protein Hydrolysates/pharmacology , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Animals , Enzyme Inhibitors/pharmacology , Humans , Peptides/pharmacologyABSTRACT
Fish protein hydrolysate (FPH) produced by incubation of Pacific hake fillet with 3.00% Protamex at pH 6.5 and 40 degrees C for 125 min demonstrated in vitro ACE-inhibitory activity (IC50 = 165 microg/mL), which was enhanced by ultrafiltration through a 10 kDa molecular weight cutoff membrane (IC50 = 44 microg/mL). However, after simulated gastrointestinal digestion, FPH and ultrafiltrate had similar ACE-inhibitory activity (IC 50 = 90 microg/mL), indicating that FPH peptides act as "pro-drug type" inhibitors and that enrichment by ultrafiltration may be unnecessary. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry confirmed that the molecular weights of major peaks were <1 kDa regardless of ultrafiltration. ACE-inhibitory activities of digested hydrolysates were not significantly affected by preincubation with ACE ( P > 0.05) and exhibited a competitive inhibitory mode. A permeability assay using fully differentiated colorectal adenocarcinoma (Caco-2) cells showed an apical to basolateral transport of peptides that ranged from approximately 2 to 20% after 2 h at 37 degrees C. Pacific hake fillet hydrolysates are a potentially bioavailable source of ACE-inhibitory peptides awaiting further in vivo study.
Subject(s)
Angiotensin-Converting Enzyme Inhibitors/metabolism , Angiotensin-Converting Enzyme Inhibitors/pharmacology , Digestion , Gadiformes , Peptides/metabolism , Peptides/pharmacology , Animals , Biological Transport , Caco-2 Cells , Humans , Hydrolysis , Models, Biological , Pancreatin/metabolism , Pepsin A/metabolism , Peptides/chemistry , Spectrometry, Mass, Matrix-Assisted Laser Desorption-IonizationABSTRACT
Natural actomyosin (NAM) from Pacific whiting (PW) showed thermal transition temperatures by circular dichroism at 31.8 and 43.1°C, which were lower than those of threadfin bream (TB) NAM, 35.0 and 49.3°C. Endothermic transitions of PW-NAM by differential scanning calorimetry were at 31.8, 42.1 and 75.3°C, compared to 36.1, 50.9 and 78.4°C for TB-NAM. Based on surface hydrophobicity, α-helical content, and solubility, PW-NAM unfolded to a greater extent than did TB-NAM when incubated at 25°C for 4h and 40°C for 2h, suggesting its lower thermal stability. Transglutaminase generally catalyzed more extensive cross-linking of PW-myosin heavy chain (MHC) than TB-MHC, and the MHC cross-linking mediated by microbial transglutaminase (MTG) was greater than by fish transglutaminase (FTG). Textural properties of PW-NAM gels increased approximately 3.6-6.1-fold and 1.3-1.5-fold in the presence of MTG and FTG, respectively.
ABSTRACT
The aim of this study was to investigate application of fish protein hydrolysates (FPHs) as cryoprotectants for cod fish mince subjected to freeze-thaw abuse. Response surface methodology revealed little difference in cryoprotectant ability between FPHs produced from Pacific hake muscle within the range of conditions studied, namely Flavourzyme® enzyme/substrate ratio (E/S 1-4%), time (1-6h) and pH (5-7). When added at 4% or higher concentrations, FPH minimized expressible moisture and cook loss, while maximizing salt extractable protein from freeze-thaw abused fish mince, providing similar or better cryoprotection compared to an 8% sucrose-sorbitol blend, and a stabilizing effect of FPH on myosin was observed by differential scanning calorimetry. Sensory evaluation showed that addition of 8% FPH in fish ball products increased the perception of fishiness, saltiness, bitterness and firmness while decreasing moistness. FPH could be a viable alternative to the sugar-based cryoprotectants currently used for frozen fish products.
Subject(s)
Gadiformes , Animals , Cryoprotective Agents , Freezing , Protein HydrolysatesABSTRACT
The objectives of this study were to apply response surface methodology to optimize fat-soluble vitamin loading in re-assembled casein micelles, and to evaluate vitamin D stability of dry formulations during ambient or accelerated storage and in fortified fluid skim milk stored under refrigeration. Optimal loading of vitamin A (1.46-1.48mg/100mgcasein) was found at 9.7mM phosphate, 5.5mM citrate and 30.0mM calcium, while optimal loading of vitamin D (1.38-1.46mg/100mg casein) was found at 4.9mM phosphate, 4.0mM citrate and 26.1mM calcium. In general, more vitamin D was retained in vitamin D-re-assembled casein micelles than control powders during storage, while vitamin D loss was not different for vitamin D-re-assembled casein micelles and control fortified milks after 21days of refrigerated storage with light exposure. In conclusion, re-assembled casein micelles with high loading efficiency show promise for improving vitamin D stability during dry storage.