ovalbumin and Hypertension

There have been studies of antihypertensive peptides derived from food proteins, but very few described the production of bioactive peptides from egg proteins. The first 2 antihypertensive peptides isolated in egg were obtained by enzymatic hydrolysis of ovalbumin. They correspond to the sequences Phe-Arg-Ala-Asp-His-Pro-Phe-Leu (ovokinin) and Arg-Ala-Asp-His-Phe-Leu (ovokinin 2-7). Both exhibited endothelium-dependent vasodilatory activity. Ovokinin (2-7) had higher antihypertensive potency than ovokinin in spontaneously hypertensive rats (SHR). Modifications in the sequence of ovokinin (2-7) improved the bioavailability of this peptide. It was also demonstrated that different ovalbumin hydrolysates can inhibit angiotensin I-converting enzyme (ACE). We recently obtained an egg white hydrolysate that inhibited the enzyme in vitro. It was obtained by treating egg white with pepsin and it exhibited antihypertensive activity in SHR. Some ACE-inhibitory peptides obtained from this hydrolysate (Tyr-Arg-Glu-Glu-Arg-Tyr-Pro-Ile-Leu, Arg-Ala-Asp-His-Pro-Phe-Leu, and Ile-Val-Phe) also showed antihypertensive activity in these rats. The egg products mentioned could be used as functional food ingredients with potential therapeutic benefit in the prevention and treatment of hypertension.

Topics: Animals; Antihypertensive Agents; Egg Proteins; Hypertension; Ovalbumin; Peptide Fragments; Rats; Rats, Inbred SHR; Rats, Inbred WKY

While animal and in vitro data demonstrate vasodilatory effects of egg white-derived peptides, human studies are lacking. We investigated for the first time the effects of an egg ovalbumin-derived protein hydrolysate on blood pressure (BP) and cardiovascular risk.. A double-blind, placebo-controlled randomized crossover trial was implemented in 75 adults aged 50-70 years with systolic BP (130-≤ 150 mmHg). Participants were randomized to an egg ovalbumin-derived protein hydrolysate (3 g/day) or placebo (3 g/day). Participants completed two 6-week periods separated by a 3-week washout.. Data from 65 participants with a mean systolic BP (135.1 ± 11 mmHg) were included. Mean office and central BP and arterial stiffness (assessed by carotid-femoral pulse wave velocity (cfPWV) or pulse wave analysis (PWA)) did not change over time and no significant differences were observed between the egg protein hydrolysate and placebo groups (P > 0.05). Similarly, no significant effects of this egg ovalbumin-derived protein hydrolysate on blood lipid and glucose concentrations (P > 0.05) were observed.. This is the first dietary intervention to investigate the effects of egg ovalbumin-derived protein hydrolysates on cardiovascular risk in humans. Despite promising findings from animal and in vitro studies, this RCT does not support the hypothesis that consumption of an egg ovalbumin-derived protein hydrolysate for 6 weeks in adults with a high-normal BP results in a reduction in BP or the modification of cardiovascular risk.

Topics: Aged; Blood Pressure; Cardiovascular Diseases; Comorbidity; Cross-Over Studies; Double-Blind Method; Female; Humans; Hypertension; Ireland; Male; Middle Aged; Ovalbumin; Protein Hydrolysates; Pulse Wave Analysis; Risk Factors

The cause of most hypertensive disease is unclear, but inflammation appears critical in disease progression. However, how elevated blood pressure initiates inflammation is unknown, as are the effects of high blood pressure on innate and adaptive immune responses. We now report that hypertensive mice have increased T cell responses to antigenic challenge and develop more severe T cell-mediated immunopathology. A root cause for this is hypertension-induced erythrocyte adenosine 5'-triphosphate (ATP) release, leading to an increase in plasma ATP levels, which begins soon after the onset of hypertension and stimulates P2X7 receptors on antigen-presenting cells (APCs), increasing APC expression of CD86. Hydrolyzing ATP or blocking the P2X7 receptor eliminated hypertension-induced T cell hyperactivation. In addition, pharmacologic or genetic blockade of P2X7 receptor activity suppressed the progression of hypertension. Consistent with the results in mice, we also found that untreated human hypertensive patients have significantly elevated plasma ATP levels compared with treated hypertensive patients or normotensive controls. Thus, a hypertension-induced increase in extracellular ATP triggers augmented APC and T cell function and contributes to the immune-mediated pathologic changes associated with hypertensive disease.

Topics: Adenosine Triphosphate; Adult; Aged; Animals; Antigens; B7-2 Antigen; Dendritic Cells; Diabetes Mellitus, Type 1; Female; Hepatitis; Humans; Hypertension; Male; Mice, Inbred C57BL; Mice, Knockout; Middle Aged; Ovalbumin; Receptors, Purinergic P2X7; T-Lymphocytes

One of the most common comorbid pathology is asthma and arterial hypertension. For experimental modeling of comorbidity we have used spontaneously hypertensive rats with ovalbumin (OVA)-induced asthma. Rats were randomly divided into three groups: control group, OVA-induced asthma group; OVA-induced asthma + IL10 shRNA interference group. Target gene (IL10) was predicted by ANDSystem. We have demonstrated that RNA-interference of IL10 affected cardiovascular (tested using Millar microcatheter system) as well as respiratory functions (tested using force-oscillation technique, Flexivent) in rats. We have shown that during RNA-interference of IL10 gene in vivo there were changes in both cardiac and lung function parameters. These changes in the cardiovascular parameters can be described as positive. But the more intensive heart workload can lead to exhaust and decompensation of the heart functions. Knockdown of IL10 gene in asthma modeling induces some positive changes in respiratory functions of asthmatic animals such as decreased elastance and increased compliance of the lungs, as well as less pronounced pathomorphological changes in the lung tissue. Thus, we provide the data about experimentally confirmed functionality changes of the target which was in silico predicted to be associated with both asthma and hypertension - in our new experimental model of comorbid pathology.

Topics: Animals; Asthma; Comorbidity; Computational Biology; Hypertension; Interleukin-10; Male; Ovalbumin; Rats; Rats, Inbred SHR; RNA, Small Interfering

To clarify the role of NO in mouse anaphylactic hypotension, effects of a nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), on antigen-induced hypotension and portal hypertension were determined in anesthetized BALB/c mice. Systemic arterial pressure (Psa), central venous pressure (Pcv), and portal venous pressure (Ppv) were directly and simultaneously measured. Mice were first sensitized with ovalbumin, and then the injection of antigen was used to decrease Psa and increase Ppv. Pretreatment with L-NAME (1 mg/kg) attenuated this antigen-induced systemic hypotension, but not the increase in Ppv. The effect of inhibitors of soluble guanylate cyclase on anaphylactic hypotension were studied with either methylene blue (3.0 mg/kg) or 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (10 mg/kg). Neither modulated any antigen-induced changes. Furthermore, methylene blue did not improve systemic hypotension induced by Compound 48/80 (4.5 mg/kg), a mast cell degranulator, which can produce non-immunological anaphylactoid reactions. These data show in anesthetized BALB/c mice that L-NAME attenuated anaphylactic hypotension without affecting portal hypertension. This beneficial effect of L-NAME appears not to depend on the soluble guanylate cyclase pathway.

Topics: Anaphylaxis; Anesthesia; Animals; Blood Pressure; Enzyme Inhibitors; Guanylate Cyclase; Hypertension; Liver Circulation; Male; Methylene Blue; Mice; Mice, Inbred BALB C; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase Type III; Ovalbumin; Oxadiazoles; Quinoxalines

The present study investigated the acute inflammatory response (increase in vascular permeability and leukocytes migration) in the pleura of spontaneously hypertensive rats (SHR) and normotensive rats (NTR), using two different stimulus: carrageenan and active anaphylaxis. In addition, the role of endogenous nitric oxide in these responses was investigated.. The inflammatory response induced by intrapleural carrageenan injection in SHR developed similarly to that in NTR. Treatment with L-NAME, reduced the intensity of this response in both groups of rats. The inflammatory response induced by active anaphylaxis in SHR and NTR was different. The increase in vascular permeability occurred later in the SHR compared to NTR. The number of leukocyte present in inflammatory exudates was increased at 4 h in both groups of rats. L-NAME treatment did not inhibit exudation at the intervals under analysis, however, reduced the number of mononuclear cells in the inflammatory exudate of SHR.. The development of the inflammatory response in SHR differs from that in NTR, depending on the nature of the inflammatory stimulus. Endogenous NO plays a clear role in carrageenan-induced inflamma-tion, but not in immunologically mediated inflammation in the analyzed period.

Topics: Anaphylaxis; Animals; Capillary Permeability; Carrageenan; Cell Migration Assays, Leukocyte; Chemotaxis, Leukocyte; Disease Models, Animal; Enzyme Inhibitors; Exudates and Transudates; Hypertension; Leukocytes; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Ovalbumin; Pleurisy; Rats; Rats, Inbred SHR; Rats, Wistar

Food-derived bioactive peptides with ACE-inhibitory properties are receiving special attention due to their beneficial effects in the treatment of hypertension. In this work we evaluate the impact of a simulated gastrointestinal digestion on the stability and activity of two bioactive peptides that derive from ovalbumin by enzymatic hydrolysis, YAEERYPIL and RADHPFL. These peptides possess in vitro ACE-inhibitory activity and antihypertensive activity in spontaneously hypertensive rats (SHR). The results showed that YAEERYPIL and RADHPFL were susceptible to proteolytic degradation after incubation with pepsin and a pancreatic extract. In addition, their ACE-inhibitory activity in vitro decreased after the simulated digestion. The antihypertensive activity on SHR of the end products of the gastrointestinal hydrolysis, YAEER, YPI, and RADHP, was evaluated. The fragments YPI and RADHP significantly decreased blood pressure, 2 h after administration, at doses of 2 mg/kg, but they probably did not exert their antihypertensive effect through an ACE-inhibitory mechanism. It is likely that RADHP is also the active end product of the gastrointestinal digestion of the antihypertensive peptides FRADHPFL (ovokinin) and RADHPF (ovokinin 2-7).

Topics: Amino Acid Sequence; Angiotensin-Converting Enzyme Inhibitors; Animals; Digestion; Drug Stability; Gastrointestinal Tract; Hydrolysis; Hypertension; Male; Models, Biological; Ovalbumin; Pancreas; Pepsin A; Peptides; Rats; Rats, Inbred SHR

RPLKPW is a potent anti-hypertensive peptide designed according to the structure of ovokinin(2-7) (RADHPF). In this study, we generated transgenic rice plants that accumulate the RPLKPW peptide as a fusion protein with the rice storage protein glutelin. The engineered peptide is expressed under the control of endosperm-specific glutelin promoters and specifically accumulates in seeds. Oral administration of either the RPLKPW-glutelin fraction or transgenic rice seeds to spontaneously hypertensive rats (SHRs) significantly reduced systolic blood pressures. These results suggest the possible application of transgenic rice seed as a nutraceutical delivery system and specifically for administration of active peptides in hypertension.

Topics: Amino Acid Sequence; Animals; Antihypertensive Agents; Base Sequence; Blood Pressure; Cell Fractionation; Genetic Vectors; Hypertension; Male; Molecular Sequence Data; Oligopeptides; Oryza; Ovalbumin; Peptide Fragments; Plants, Genetically Modified; Plasmids; Rats; Rats, Inbred SHR; Seeds

This work reports the antioxidant activity of peptides produced by enzymatic hydrolysis of crude egg white with pepsin. Four peptides included in the protein sequence of ovalbumin possessed radical scavenging activity higher than that of Trolox. The hydrolysate of egg white with pepsin for 3 h was previously found to exhibit a strong angiotensin I-converting enzyme (ACE) inhibitory activity in vitro. The combined antioxidant and ACE inhibition properties make it a very useful multifunctional preparation for the control of cardiovascular diseases, particularly hypertension. No correlation was found between antioxidant and ACE inhibitory activities. However, the peptide Tyr-Ala-Glu-Glu-Arg-Tyr-Pro-Ile-Leu, which was a strong ACE inhibitor (50% inhibitory concentration, 4.7 microM) also exhibited a high radical scavenging activity (oxygen radical absorbance capacity-fluorescein value, 3.8 micromol of Trolox equivalent per micromol of peptide) and delayed the low-density lipoprotein lipid oxidation induced by Cu2+ at a concentration of approximately 0.16 mg/mg of low-density lipoprotein. Present results support that antioxidant peptides and amino acids not only act individually, but also cooperatively and synergistically.

Topics: Amino Acid Sequence; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Antioxidants; Cholesterol, LDL; Egg Proteins; Free Radical Scavengers; Hydrolysis; Hypertension; Ovalbumin; Pepsin A; Peptide Fragments

Food proteins can be a source of various bioactive peptides including such possessing anti-hypertensive activity. While most orally active anti-hypertensive peptides derived from food proteins inhibit the angiotensin I-converting enzyme (ACE), ovokinin (2-7) (RADHPF), a peptide isolated from a chymotryptic digest of ovalbumin, has been shown to induce nitric oxide-dependent vasorelaxation in an isolated mesenteric artery as well as anti-hypertensive effect after oral administration in spontaneously hypertensive rats (SHRs). Rational amino acid replacement lead to the ovokinin (2-7) analog, RPLKPW, which had the highest anti-hypertensive activity among the tested peptides. Furthermore, oral administration (0.1 mg/kg) of the peptide lowered the blood pressure of SHR but not of normotensive Wistar-Kyoto (WKY) rats. In order to develop a novel use of this potent anti-hypertensive peptide for prevention of hypertension, RPLKPW has been genetically introduced into the homologous sequences in soybean beta-conglycinin alpha' subunit by site-directed mutagenesis. The recombinant RPLKPW-incorporated alpha' subunit expressed in E. coil has been shown to exert anti-hypertensive activity after oral administration in SHR. Thus, RPLKPW-incorporated alpha' subunit is the first example of a genetically modified food protein possessing physiological activity based on a bioactive peptide.

Topics: Animals; Antihypertensive Agents; Drug Design; Egg Proteins; Hypertension; Mutagenesis, Site-Directed; Nitric Oxide; Ovalbumin; Peptide Fragments; Peptidyl-Dipeptidase A; Rats; Soybean Proteins; Vasodilation

X-ray contrast media (CM) toxicity resembles IgE-antigen-based anaphylaxis, and CM-related histamine release has been demonstrated in vitro and in vivo. While nobody has succeeded in producing antibodies against injections of neat CM, the ability of CM to compete with a series of antigens against their respective antibodies has recently been demonstrated. However, there is a paradox, since the CM with the strongest antibody binding are nevertheless the least likely to provoke antigen-antibody-related mast cell/basophil release.. Two strains of rats were subjected to (a) passive cutaneous anaphylaxis (PCA) studies in the presence of various concentrations of CM, (b) blood pressure (BP) tracings following bolus administrations of various prototypical CM and (c) BP tracings in ovalbumin (OVA)-sensitized rats, challenged with OVA plus CM, vs. OVA plus CM-equivalent saline.. In the PCA studies, and the OVA challenge studies, the CM appear to act in an antigen excess mode, limiting the potential of the OVA to elicit anaphylactic changes, as demonstrated by permeability studies or by BP levels. The bolus CM studies demonstrate that the more potent CM 'antigens' actually produce an increase in BP and the less potent CM 'antigens', a drop in BP. These changes can be related to the CM acting in an 'antigen' excess mode vs. an 'antigen' equivalent mode.. The CM have the potential to act in an 'antigen' excess or 'antigen'-equivalent mode. The potential to express an 'antigen'-excess mode in vivo, may be unique to CM because of the high concentrations injected.

Topics: Animals; Antigen-Antibody Reactions; Antigens; Blood Pressure; Contrast Media; Histamine Release; Hypertension; Hypotension; Ioxaglic Acid; Nitric Oxide; Ovalbumin; Passive Cutaneous Anaphylaxis; Rats; Rats, Inbred BN; Rats, Sprague-Dawley; Triiodobenzoic Acids

Spontaneously hypertensive (SH) rats immunized with mouse renin produce anti-renin antibodies, responsible for down-modulation of blood pressure, associated with an infiltration of kidneys by mononuclear cells. In this work, anti-renin T cells from SH rats immunized with renin have been stimulated in vitro, and we have studied in vitro and in vivo their effect on anti-renin antibody production by normal syngeneic B cells. We show that, in vitro, renin-activated T cells induce a renin-specific antibody response without addition of exogenous renin. Anti-renin T cells injected into naive SH rats trigger normal B cells to secrete high amounts of monospecific anti-renin IgG antibodies as early as day 5. These antibodies interfere with the homeostasis of the renin-angiotensin system leading to the normalization of blood pressure without any nephritis. These results show that anti-renin B cells are either not tolerant per se or in a reversible state of anergy. Our results also suggest that anti-renin B cells constitutively express renin-derived peptides in such a way that they may be stimulated by activated anti-renin T cells; these cells express IL-4 mRNA indicating that IL-4 could play a role in the differentiation of B cells.

Topics: Animals; Antibody Formation; B-Lymphocytes; Base Sequence; Cell Communication; Cells, Cultured; Flow Cytometry; Hypertension; Immunization; Interferon-gamma; Interleukin-2; Lymphocyte Activation; Male; Molecular Sequence Data; Ovalbumin; Rats; Rats, Inbred SHR; Renin; T-Lymphocytes

Topics: Acute Disease; Anaphylaxis; Animals; Apnea; Carotid Arteries; Erythrocyte Count; Hemodynamics; Histamine; Hypersensitivity, Immediate; Hypertension; Hypertension, Pulmonary; Leukocyte Count; Leukopenia; Ovalbumin; Swine; Swine Diseases; Thrombocytopenia