Intranasal Administration Of Peptides Research Articles

HLDF-6 peptides exhibit neuroprotective effects in the experimental model of preclinical Parkinson's disease

The mechanisms of the neuroprotective action of the hexapeptides HLDF-6 encoded by the amino acid sequence 41–46 of Human Leukemia Differentiation Factor and its homoserine derivative HLDF-6H were studied in an experimental 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced model of Parkinson's disease (PD). C57Bl/6 mice received two intraperitoneal injections of 18 mg/kg MPTP-HCl, with an interval of 2 hours. MPTP-induced motor dysfunction was assessed using horizontal grid test. Our data show that chronic intranasal administration of peptides (3 weeks, 300 μg/kg/day) restored normal levels of dopamine and improved its turnover rates in the striatum. Furthermore, peptide administration increased serum estradiol levels and led to a significant improvement in motor functions in MPTP-treated mice. Additionally, peptide treatment increased the levels of mRNA encoding neurotrophin BDNF, but normalized the levels of mRNA encoding the inflammatory mediators TGFβ1, IL1β and IFNγ in the brain. Collectively, our behavioral and biochemical studies demonstrate that HLDF-6 peptides have a therapeutic potential for treating PD. We propose that HLDF-6 peptides may exert their neuroprotective mechanism, at least in part, by normalizing estradiol levels and modulating the expression of key factors involved in neurotrophic support and neuroinflammation.

Conditioned place preference of kisspeptin-10

INTRODUCTION: Kisspeptins (KISS), a group of brain neuropeptides are involved in sexual behavior. KISS activate the hypothalamic neurons that synthesize gonadotropin releasing hormone. KISS was also detected in the limbic system. Earlier, we showed the activation of sexual motivation after the administration of kisspeptin-10 without increasing the level of testosterone in male rats, which suggests the extrahypothalamic effect of KISS.
 The aim of this work was to study the possibility of aquisition of conditioned place preference of kisspeptin-10, as well as to study the emotional and investigational behavior in rats after intranasal peptide administration.
 METHODS: Conditioned place preference test (CPP), open field test (OP) and elevated plus maze (EPM) were used in male Wistar rats.
 RESULTS: When studying CPP, animals spent 78.6 6.3% of the time in the chamber associated with the administration of KISS compared to control animals with administration of physiological saline (51.2% of the experiment time; p 0.05). After kisspeptin-10 administration locomotor activity was 2-fold increased (p 0.05), and the number of sniffings was 2-fold increased too (p 0.05). The parameters did not significantly differ in animals treated with kisspeptin or saline in PCL.
 CONCLUSION: Thus repeated intranasal administration of kisspeptin-10 induces the aquisition of CPP in rats. This suggests that kisspeptin-10 can cause activity in the reward system or the activation of brain regions associated with this system, which ultimately leads to the formation of an emotionally positive state.

Участие лизинсодержащих олигопептидов в регуляции свертывания крови

Установлено регуляторное влияние лизинсодержащих пептидов Arg-Lys-Lys-Arg-Pro-Gly-Pro (RKKRPGP) и Lys-Arg-Lys-Pro-Gly-Pro (KRKPGP) на процессы свертывания крови животных. Многократное в течение 7 сут через каждые 24 ч пероральное или интраназальное введение пептидов в ежедневной дозе 100 мкг/кг массы тела крыс приводило к снижению антитромбоцитарной активности на 29 – 49 %, активности фактора XIIIa — на 15 – 49 %. При этом повышалась антикоагулянтная активность плазмы крови крыс по тесту активированного частичного тромбопластинового времени на 16 – 33 %, по тесту тромбинового времени — на 23 – 57 %. Кроме того, под влиянием пептида KRKPGP снижалась концентрация свертываемого тромбином фибриногена на 47 – 49 %. Поскольку оба пептида при пероральном и интраназальном применении в разной степени проявляли в здоровом организме антитромбоцитарную, антикоагулянтную активность и снижали активность фактора свертывания ХШа, сделан вывод, что лизинсодержащие пептиды участвуют в регуляции свертывания крови и могут считаться перспективными антитромботическими веществами.

Design of enkephalin modifications protected from brain extracellular peptidases providing long-term analgesia

The main obstacle to the use of many therapeutic peptides in practice is their rapid destruction by extracellular peptidases. Earlier we have found that active in the extracellular medium of mammalian brain exopeptidases are unable to break the bonds formed by β-alanine. We have designed several modified forms of opioid peptide enkephalin (Tyr-Gly-Gly-Phe-Met; Enk) with end βAla: ModEnk1 (βAla-Tyr-Gly-Gly-Phe-Met-βAla), ModEnk2 (βAla-Tyr-Gly-Gly-Phe-NH2), ModEnk3 (βAla-Tyr-Gly-Phe-NH2). These modifications are much more stable than Enk in the suspension of isolated axonal endings (synaptosomes) that mimics the brain extracellular medium. ModEnk1-3 have been tested in standard “pain” experiment “tail flick” on rats using intranasal peptide administration. ModEnk1 and ModEnk2 (but not ModEnk3) have fully preserved pain-relieving properties of Enk, but their efficiency was maintained for much longer. Compared to ModEnk1, ModEnk2 is more stable and provides longer analgesia because it is less accessible for endopeptidases. They are potent non-toxic analgesics.

Effects of intranasal administration of the peptide antagonist of type I vaniloid receptor (TRPV1) in the rodent central nervous system.

Intranasal administration of the polypeptide APHC3, an antagonist of the TRPV1 receptor, had acute anxiolytic and antidepressant effects, as well as an ability to modify the microglial response to proinflammatory stress and cytokine profile of the hippocampus. However, the acute antidepressant effect of the polypeptide was not related to the attenuation of neuroiflammation and probably had a different mechanism. The use of intranasal administration of the APHC3 peptide as a therapeutic approach aimed at decreasing depression symptoms needs additional studies in order to find the mechanism of action of this polypeptide in the central nervous system (CNS).

176. Novel Molecules That Enhance Adenovirus Transduction of the Airway Epithelium: Reinvigorating Adenovirus-Mediated Gene Therapy

Adenovirus remains the most common vector system used in gene therapy clinical trials worldwide and several adenoviral vectors show promise in phase III clinical trials. One major limitation to the efficacy of adenovirus-mediated gene therapy is low transduction due to the limited primary receptor availability in most tissues. Interventions able to boost adenovirus transduction would have significant implications for both improving transduction and lowering the viral dose below the immunogenic threshold. Most human and several key animal adenoviruses share a common receptor with group B coxsackieviruses named the coxsackievirus and adenovirus receptor (CAR). CAR has several alternatively spliced isoforms. We have recently discovered that the eight-exon isoform (CAREx8) can specifically localize to the apical membrane of polarized primary human airway epithelia where it can mediate apical adenovirus infection. Moreover, we have discovered that CAREx8 is both positively and negatively regulated by the cellular scaffolding protein MAGI-1. We hypothesized that cell permeable decoy peptides targeting the interaction between MAGI-1 and CAREx8 would increase CAREx8 protein levels and increase AdV transduction. Tat-conjugated peptide entry into polarized epithelia was confirmed by mass spectrometry and fluorescence microscopy. Relative to control, peptides increased the levels of CAREx8 at the apical surface of polarized epithelia and significantly increased AdV entry and transduction, as measured by apical surface biotinylation, qPCR, and AdV5-β-Gal transduction. Moreover, AdV5 transduction was increased by 300-500% after intranasal peptide administration in mice demonstrating in vivo activity. To determine the mechanism of action, we followed the synthesis and co-localization of CAREx8 with key molecules in the cellular ER-Golgi-vesicular trafficking pathways. We found that CAREx8 was in compartments distinct from MAGI-1 and spread throughout the apical trafficking pathway and at the apical surface of the epithelium. Removal of the peptides reversed both the amount and localization of CAREx8 and returned the susceptibility of the epithelium to baseline. Taken together, these data indicate that decoy peptides able to block the MAGI-1-CAREx8 interaction transiently increase adenovirus-mediated gene transfer and offer the potential to increase the efficacy of adenovirus-mediated gene therapy.

Intranasal peptide-induced tolerance and linked suppression: consequences of complement deficiency.

A role for complement, particularly the classical pathway, in the regulation of immune responses is well documented. Deficiencies in C1q or C4 predispose to autoimmunity, while deficiency in C3 affects the suppression of contact sensitization and generation of oral tolerance. Complement components including C3 have been shown to be required for both B-cell and T-cell priming. The mechanisms whereby complement can mediate these diverse regulatory effects are poorly understood. Our previous work, using the mouse minor histocompatibility (HY) model of skin graft rejection, showed that both C1q and C3 were required for the induction of tolerance following intranasal peptide administration. By comparing tolerance induction in wild-type C57BL/6 and C1q-, C3-, C4- and C5-deficient C57BL/6 female mice, we show here that the classical pathway components including C3 are required for tolerance induction, whereas C5 plays no role. C3-deficient mice failed to generate a functional regulatory T (Treg) –dendritic cell (DC) tolerogenic loop required for tolerance induction. This was related to the inability of C3-deficient DC to up-regulate the arginine-consuming enzyme, inducible nitric oxide synthase (Nos-2), in the presence of antigen-specific Treg cells and peptide, leading to reduced Treg cell generation. Our findings demonstrate that the classical pathway and C3 play a critical role in the peptide-mediated induction of tolerance to HY by modulating DC function.

Molecular Mechanisms of Induction of Antigen-Specific Allograft Tolerance by Intranasal Peptide Administration

We have previously shown that intranasal (i.n.) administration of a single MHC class II-restricted HY peptide to female mice induces tolerance to up to five additional epitopes expressed on test male grafts, a phenomenon known as linked suppression. In this study, we investigated the molecular mechanisms involved both in the induction phase following peptide administration and during linked suppression after grafting. We report that following initial i.n. administration, peptide is widely disseminated and is presented by functionally immature dendritic cells. These fail to cause optimal stimulation of the responding HY-specific CD4(+) T cells that express genes characteristic of regulatory T cells. Following i.n. peptide plus LPS administration, causing immunization, HY-specific CD4(+) T cells express genes characteristic of activated T cells. We further find that following male skin grafting, HY-specific CD8(+) T cells from peptide-treated tolerant mice display both quantitative and qualitative differences compared with similar cells from untreated mice that reject their grafts. In tolerant mice there are fewer HY-specific CD8(+) cells and they express several genes characteristic of exhausted T cells. Furthermore, associated with specific chemokine receptor and integrin expression, HY-specific CD8(+) T cells show more limited migration from the graft draining lymph node into other tissues.

Leptin‐based glycopeptide induces weight loss and simultaneously restores fertility in animal models

To design, manufacture and test a second generation leptin receptor (ObR) agonist glycopeptide derivative. The major drawback to current experimental therapies involving leptin protein is the appearance of treatment resistance. Our novel peptidomimetic was tested for efficacy and lack of resistance induction in rodent models of obesity and appetite reduction. The glycopeptide containing two additional non-proteinogenic amino acids was synthesized by standard solid-phase methods. Normal mice were fed with peanuts until their blood laboratory data and liver histology showed typical signs of obesity but not diabetes. The mice were treated with the peptidomimetic at 0.02, 0.1 or 0.5 mg/kg/day intraperitoneally side-by-side with 0.1 mg/kg/day leptin for 11 days. After termination of the assay, the blood cholesterol and glucose amounts were measured, the liver fat content was visualized and quantified and the remaining mice returned to normal diet and were allowed to mate. In parallel experiments normal rats were treated intranasally with the glycopeptide at 0.1 mg/kg/day for 10 days. The 12-residue glycosylated leptin-based peptidomimetic E1/6-amino-hexanoic acid (Aca) was designed to target a principal leptin/ObR-binding interface. E1/Aca induced leptin effects in ObR-positive cell lines at picomolar concentrations and readily crossed the blood-brain barrier (BBB) following intraperitoneal administration. The peptide initiated typical leptin-dependent signal transduction pathways both in the presence and absence of leptin protein. The peptide also reduced weight gain in mice fed with high-fat peanut diet in a dose-dependent manner. Obese mice receiving peptide E1/Aca at a 0.5 mg/kg/day dose lost weight, corresponding to a net 6.5% total body weight loss, while similar mice treated with leptin protein did not. Upon cessation of the weight loss treatment, several obesity-related pathologies (i.e. abnormal metabolic profile and liver histology as well as infertility) normalized in peptide-, but not leptin-treated, mice. Peptide E1/Aca added intranasally to growing normal rats decelerated normal weight gain corresponding to a net 6.8% net total body weight loss with statistical significance. No resistance induction to peptide E1/Aca or toxicity in either obese or healthy rodents was observed, indicating the potential for widespread utility of the peptidomimetic in the treatment of leptin-deficiency disorders. We provide additional proof for the hypothesis that difficulties in current leptin therapies reside at the BBB penetration stage, and we document that by either glycosylation or intranasal peptide administration we can overcome this limitation.

INTRANASAL INSULIN IMPROVES COGNITION AND MODULATES β-AMYLOID IN EARLY AD

Background: Reduced brain insulin signaling and low CSF-to-plasma insulin ratios have been observed in patients with Alzheimer disease (AD). Furthermore, intracerebroventricular or IV insulin administration improve memory, alter evoked potentials, and modulate neurotransmitters, possibly by augmenting low brain levels. After intranasal administration, insulin-like peptides follow extracellular pathways to the brain within 15 minutes. Objective: We tested the hypothesis that daily intranasal insulin treatment would facilitate cognition in patients with early AD or its prodrome, amnestic mild cognitive impairment (MCI). The proportion of verbal information retained after a delay period was the planned primary outcome measure. Secondary outcome measures included attention, caregiver rating of functional status, and plasma levels of insulin, glucose, β-amyloid, and cortisol. Methods: Twenty-five participants were randomly assigned to receive either placebo (n = 12) or 20 IU BID intranasal insulin treatment (n = 13) using an electronic atomizer, and 24 participants completed the study. Participants, caregivers, and all clinical evaluators were blinded to treatment assignment. Cognitive measures and blood were obtained at baseline and after 21 days of treatment. Results: Fasting plasma glucose and insulin were unchanged with treatment. The insulin-treated group retained more verbal information after a delay compared with the placebo-assigned group ( p = 0.0374). Insulin-treated subjects also showed improved attention ( p = 0.0108) and functional status ( p = 0.0410). Insulin treatment raised fasting plasma concentrations of the short form of the β-amyloid peptide (Aβ40; p = 0.0471) without affecting the longer isoform (Aβ42), resulting in an increased Aβ40/42 ratio ( p = 0.0207). Conclusions: The results of this pilot study support further investigation of the benefits of intranasal insulin for patients with Alzheimer disease, and suggest that intranasal peptide administration may be a novel approach to the treatment of neurodegenerative disorders.

Prophylactic and Therapeutic Potential of Asp f1 Epitopes in Naïve and Sensitized BALB/c Mice

BackgroundThe present study examines a hypothesis that short allergen-derived peptides may shift an Aspergillus fumigatus (Afu-) specific TH2 response towards a protective TH1. Five overlapping peptides (P1-P5) derived from Asp f1, a major allergen/antigen of Afu, were evaluated for prophylactic or therapeutic efficacy in BALB/c mice.MethodsTo evaluate the prophylactic efficacy, peptides were intranasally administered to naïve mice and challenged with Afu-allergens/antigens. For evaluation of therapeutic efficacy, the mice were sensitized with Afu-allergens/antigens followed by intranasal administration of peptides. The groups were compared for the levels of Afu-specific antibodies in sera and splenic cytokines evaluated by ELISA. Eosinophil peroxidase activity was examined in the lung cell suspensions and lung inflammation was assessed by histopathogy.ResultsPeptides P1-, P2- and P3 decreased Afu-specific IgE (84.5~98.9%) and IgG antibodies (45.7~71.6%) in comparison with Afu-sensitized mice prophylactically. P1- and P2-treated ABPA mice showed decline in Afu-specific IgE (76.4~88%) and IgG antibodies (15~54%). Increased IgG2a/IgG1 and IFN-γ/IL-4 ratios were observed. P1-P3 prophylactically and P1 therapeutically decreased IL-5 levels and eosinophil peroxidase activity. P1 decreased inflammatory cells' infiltration in lung tissue comparable to non-challenged control.ConclusionAsp f1-derived peptide P1, prophylactically and therapeutically administered to Balb/c mice, is effective in regulating allergic response to allergens/antigens of Afu, and may be explored for immunotherapy of allergic aspergillosis in humans.

Intranasal insulin improves cognition and modulates β-amyloid in early AD

Reduced brain insulin signaling and low CSF-to-plasma insulin ratios have been observed in patients with Alzheimer disease (AD). Furthermore, intracerebroventricular or IV insulin administration improve memory, alter evoked potentials, and modulate neurotransmitters, possibly by augmenting low brain levels. After intranasal administration, insulin-like peptides follow extracellular pathways to the brain within 15 minutes. We tested the hypothesis that daily intranasal insulin treatment would facilitate cognition in patients with early AD or its prodrome, amnestic mild cognitive impairment (MCI). The proportion of verbal information retained after a delay period was the planned primary outcome measure. Secondary outcome measures included attention, caregiver rating of functional status, and plasma levels of insulin, glucose, beta-amyloid, and cortisol. Twenty-five participants were randomly assigned to receive either placebo (n = 12) or 20 IU BID intranasal insulin treatment (n = 13) using an electronic atomizer, and 24 participants completed the study. Participants, caregivers, and all clinical evaluators were blinded to treatment assignment. Cognitive measures and blood were obtained at baseline and after 21 days of treatment. Fasting plasma glucose and insulin were unchanged with treatment. The insulin-treated group retained more verbal information after a delay compared with the placebo-assigned group (p = 0.0374). Insulin-treated subjects also showed improved attention (p = 0.0108) and functional status (p = 0.0410). Insulin treatment raised fasting plasma concentrations of the short form of the beta-amyloid peptide (A beta 40; p = 0.0471) without affecting the longer isoform (A beta 42), resulting in an increased A beta 40/42 ratio (p = 0.0207). The results of this pilot study support further investigation of the benefits of intranasal insulin for patients with Alzheimer disease, and suggest that intranasal peptide administration may be a novel approach to the treatment of neurodegenerative disorders.

Therapeutic effects of glyprolines (PGP, GP, and PG) in rats with stress-induced behavioral disorders

Experiments on male outbred albino rats showed that stress (10-min swimming) increased anxiety and inhibited orientation and exploratory activities. Poststress (15 min after the end of swimming) intranasal administration of peptides Pro-Gly-Pro and Gly-Pro in a dose of 3.7 micromol/kg prevented stress-induced behavioral disorders. This effect persisted for 3 h.

IL-10 is essential for disease protection following intranasal peptide administration in the C57BL/6 model of EAE

We have shown previously that intranasal administration of encephalitogenic peptides in soluble form to H-2 u and H-2 s mice affords protection from experimental autoimmune encephalomyelitis (EAE). Here we demonstrate that this method of disease protection can be induced in C57BL/6 mice by administration of the soluble peptide 35–55 from myelin oligodendrocyte glycoprotein. This protective effect was demonstrated by the evaluation of both clinical EAE scores and central nervous system histopathology; the latter showing minimal inflammatory infiltrates in treated mice. The employment of an IL-10 −/− congenic strain allowed an appraisal of the involvement of IL-10 in this process. The lack of disease protection in these mice clearly demonstrates the non-redundant role of IL-10 in this process.

Intranasal oxytocin administration attenuates the ACTH stress response in monkeys

Social relationships protect against the development of stress-related psychiatric disorders, yet little is known about the neurobiology that regulates this phenomenon. Recent evidence suggests that oxytocin (OT), a neuropeptide involved in social bond formation, may play a role. This experiment investigated the effects of chronic intranasal OT administration on acute stress-induced hypothalamic-pituitary-adrenal (HPA) axis activation in adult female squirrel monkeys. Subjects were randomized to one of two experimental conditions. Monkeys were intranasally administered either 50 microg oxytocin (N = 6 monkeys) or 0 microg oxytocin (N = 6 monkeys)/300 microl saline once a day for eight consecutive days. Immediately after drug administration on the eighth day, all monkeys were exposed to acute social isolation. Blood samples for determinations of adrenocorticotropic hormone (ACTH) and cortisol concentrations were collected after 30 and 90 min of stress exposure. Consistent with an anti-stress effect, OT-treated monkeys exhibited lower ACTH concentrations compared to saline-treated monkeys after 90 min of social isolation (F(1,7) = 6.891; P = 0.034). No drug-related differences in cortisol levels were observed, indicating that OT does not directly attenuate the adrenal stress response. Intranasal peptide administration has been shown to penetrate the central nervous system, and research must determine whether intranasally delivered OT exerts its effect(s) at a pituitary and/or brain level. This primate model offers critical opportunities to improve our understanding of the anti-stress effects of OT and may lead to novel pharmacological treatments for stress-related psychiatric disorders.

Natural and Induced Regulatory T Cells

Mucosal antigen delivery can induce tolerance, as shown by suppression of subsequent responses to antigen. Our previous work showed that both intranasal and oral routes of antigen delivery were effective but indicated that the intranasal route might be more reliable. Intranasal peptide administration induced cells that could mediate bystander suppression of responses to associated antigenic epitopes. Here, we discuss further investigation into the nature of intranasal, peptide-induced tolerance. Cells from mice treated with intranasal peptide became anergic and shut down secretion of cytokines such as IL-2, but still secreted IL-10. This latter cytokine was required for suppression of immune responses in vivo even though suppression of responses in vitro was IL-10 independent. Intranasal peptide induced a subset of CD25(-), CTLA-4(+) regulatory cells that suppressed naive cell function in vitro and in vivo. We provide evidence that these cells arise from CD25(-) precursors and differentiate independently from natural CD25(+) regulatory cells. IL-10-secreting regulatory cells are also found in the peripheral blood of humans and can be induced by soluble peptide administration. This route of tolerance induction offers promise as a means of antigen-specific immunotherapy of allergic and autoimmune conditions in humans.

Kinetics and mode of peptide delivery via the respiratory mucosa determine the outcome of activation versus TH2 immunity in allergic inflammation of the airways.

Specific immunotherapy involving systemic injection of allergen, though highly effective, can cause severe side effects due to IgE-mediated activation of effector cells. Allergen-derived peptides might provide a safer alternative. We have investigated the use of mucosally delivered peptide to induce CD4(+) T(H)2 cell tolerance and thus protect against allergen-induced airway inflammation. The purpose of this study was to investigate whether intranasal administration of an allergen-derived peptide, either alone or adsorbed to chitosan, can prevent the induction of T(H)2-mediated pulmonary inflammation after sensitization and challenge of the airways with allergen. Mice were given (intranasally) a peptide containing an immunodominant epitope of the Dermatophagoides pteronyssinus (Der p) 1 allergen, either as soluble antigen or adsorbed to chitosan, before sensitization and allergen challenge. Pulmonary inflammation, antigen-specific CD4(+) T-cell responses, and antibody levels in sera were then determined. Mice given peptide adsorbed to chitosan had significant reductions in airway eosinophilia, which correlated with reduced levels of IL-4 and IL-5 in the bronchoalveolar lavage fluid. There was decreased recruitment of activated CD4(+) T cells into the airways after allergen challenge, which correlated with a loss of Der p 1-specific T-cell cytokine responses in the periphery and the localized production of IL-10 by antigen-specific T cells in bronchial lymph nodes. Induction of peripheral T-cell tolerance was preceded by transient T-cell activation and IFN-gamma production. Our data demonstrate that suppression of airway inflammation by intranasal administration of peptide antigen adsorbed to chitosan is initiated by transient T-cell activation and maintained by the production of IL-10 by antigen-specific T cells in the draining lymph nodes.

Hypersensitivity reactions after respiratory sensitization: effect of intranasal peptides containing T-cell epitopes.

The intranasal administration of peptides containing T-cell epitopes has been shown to inhibit T-cell and antibody responses of mice injected with allergen, but responses to respiratory sensitization might be regulated differently. This study was designed to examine the effect of intranasal peptide on antigen-induced lung inflammatory responses and delayed hypersensitivity after sensitization by the respiratory mucosa or without sensitization. Mice were treated with an intranasal tolerizing regimen of a peptide containing the major T-cell epitope of Der p 1. Delayed hypersensitivity and lung inflammation to challenge with Der p 1 was measured either without further treatment or after sensitization induced by means of the intranasal administration of Der p 1 with a mutated enterotoxin adjuvant. Lung inflammatory responses were examined by means of lavage and histologic section, and delayed hypersensitivity responses were measured on the basis of ear swelling. Delayed hypersensitivity reactions were induced in mice treated with intranasal peptide, and large reactions were found in mice given intranasal peptide and sensitized with intranasal Der p 1 and adjuvant. Mice pretreated with peptide and sensitized with Der p 1 had an increased lymphocytic infiltration after allergen-specific challenge, as measured by means of bronchoalveolar lavage and shown histologically. These hypersensitivity results are in contrast to previous data that show tolerance to injected antigen. Although the intranasal administration of a peptide containing a T-cell epitope markedly inhibits responses to sensitization produced by the injection of allergen, the peptide induces immune responses and increases hypersensitivity to respiratory sensitization.

Inhibition of mucosal and systemic T(h)2-type immune responses by intranasal peptides containing a dominant T cell epitope of the allergen Der p 1.

Although the intranasal administration of peptides containing T cell epitopes has been shown to be a potent method of inhibiting responses to the allergen Der p 1, the experiments to date have concentrated on their ability to regulate immune responses to the injection of antigen in a T(h)1-type adjuvant. Their ability to regulate responses to a T(h)2-type immunization and to sensitization via the respiratory mucosa has not been examined. Here it is shown that peptide used in doses required to block delayed-type hypersensitivity can also readily inhibit IgE responses to Der p 1 injected in alum. To examine responses induced in the respiratory mucosa, mice pretreated with intranasal peptide were sensitized with an intranasal dose of Der p 1 in conjunction with a mutated enterotoxin adjuvant. Intranasal peptide even in very high doses did not reduce IgE titers, but the ability of cells from the draining lymph nodes to release IL-4 and IL-13 but not IL-2, IL-5, IL-10 or IFN-gamma was reduced. These are the first reports on the effect of intranasal peptides containing T cell epitopes on IgE in T(h)2 immunization and on responses to respiratory immunization. Thus the effect of the peptide-induced mucosal tolerance differs depending on the type of immunization used for sensitization, but the potential to inhibit T(h)2 responses and responses to respiratory sensitization as well as T(h)1 responses has been demonstrated.

Intranasal administration of calcitonin and of other peptides: Studies with different promoters

Peptide hormones can only be administered by the injective route, not by the oral route: injective therapy has several drawbacks, being non physiologic, poorly reproducible and with a poor patient compliance over prolonged treatments. This explains the interest for alternative routes of peptide administration, in particular for the intranasal route. Intranasal administration of peptides with a short molecule (10 amino acids or less) is now routinely performed in the clinical setting, although their bioavailability is low. In order to be absorbed through the nasal mucosa peptides like insulin, glucagon, GHRH and CRH require the presence of substances, called surfactants or promoters. Salmon calcitonin (sCT) is readily absorbed and shows appreciable metabolic effects and clinical efficacy, with a clear dose-effect ratio both in normal subjects and in post-menopausal women: some data also show a similar effect of sCT and carbicalcitonin. Human calcitonin (hCT) has a lower biological efficacy than sCT and is poorly absorbed: various promoters allow significant nasal absorption and preliminary data show a significant clinical efficacy of hCT thus administered. Also glucagon is absorbed through the nasal mucosa only in the presence of promoters and exerts clear metabolic effects in patients with hypoglycaemia. Surfactants are potentially toxic, so that new approaches are required: poor solubility and polymerization might be responsible for poor nasal absorption: however, cyclodextrins that enhance solubility, were without effect on absorption of glucagon: similarly, monomeric insulin was not absorbed in the absence of promoters. At present, the use of promoters seems justified only for peptides with a poor spontaneous absorption.