Allergen Stability and Immunological Reactivity during Co-dissolution and Incubation of House Dust Mite and Japanese Cedar Pollen SLIT-Tablets.

Japanese allergic subjects are commonly sensitized to both house dust mite (HDM) and Japanese cedar pollen (JCP) and combined treatment with sublingual immunotherapy (SLIT) tablets is desirable. However, mixing extracts of two non-homologous allergens may compromise allergen stability and affect the clinical outcome. Therefore, we investigated the stability of major allergens and total allergenic reactivity of HDM and JCP SLIT-tablets following dissolution in human saliva or artificial gastric juice. Two fast-dissolving freeze-dried SLIT-tablets were completely dissolved and incubated at 37 °C. Major allergen concentrations and total allergenic reactivity were measured. After mixing and co-incubation of HDM and JCP SLIT tablets in human saliva for 10 min at 37°C, there were no statistically significant changes in major allergen concentrations. In addition, no loss of allergenic reactivity of the mixed two SLIT-tablet solutions was seen. In contrast, complete loss of allergenic reactivity and detectable major allergen concentrations occurred when the two SLIT-tablets were dissolved and incubated in artificial gastric juice. These results demonstrate that HDM or JCP major allergens and the total allergenic reactivity of both SLIT-tablets measured here remain intact after dissolution and co-incubation in human saliva, supporting the possibility of a dual HDM and JCP SLIT-tablet administration regimen if clinically indicated. The complete loss of allergenic reactivity after incubation in artificial gastric juice can furthermore be taken to indicate that the immunological activity of the allergen extracts contained in the two SLIT-tablets is likely to be lost or severely compromised upon swallowing.

The Importance of Tablet Formulation on Allergen Release Kinetics and Efficiency: Comparison of Freeze-dried and Compressed Grass Pollen Sublingual Allergy Immunotherapy Tablet Formulations.

PURPOSE: Efficient delivery of allergens to the sublingual mucosa is a prerequisite for successful sublingual immunotherapy (SLIT) for allergy, and in order to become available to immune-competent cells embedded in the sublingual mucosa, allergens need to be delivered in a soluble form. Delivery of solubilized allergens poses a particular challenge for tablet-based allergy immunotherapy, in which allergens are administered under the tongue in the form of dry tablets and need to be dissolved rapidly in a small volume of saliva, with little or no agitation. The purposes of this article were to compare the properties of 2 different pharmaceutical SLIT-tablet formulations, freeze-dried and compressed, and to examine how the tablet formulation affects the efficiency with which allergen is delivered from the dry state of the tablet into soluble form. METHODS: Two SLIT-tablet formulations, both indicated for grass pollen allergic rhinitis and containing grass pollen extract as the active ingredient, were examined with regard to tablet disintegration times, allergen dissolution kinetics, dependency on solvent volume and agitation, and the achieved recovery of the grass allergen content in soluble form with each tablet. FINDINGS: The freeze-dried and the compressed SLIT-tablet formulations differed markedly with respect to efficiency of allergen release. The freeze-dried tablet disintegrated faster and released grass allergen into solution with a release rate higher than that of the compressed formulation and, in contrast to the compressed formulation, achieved full recovery of the allergen content in soluble form in a small volume of solvent. IMPLICATIONS: Rapid and complete release of soluble allergen in a small volume of solvent, as demonstrated by the freeze-dried formulation, are key elements of efficient sublingual allergen delivery by SLIT-tablets. Complete allergen release means that the full allergen dose of the tablet is recovered from the tablet and made available to the sublingual immune system in soluble form, and rapid release ensures that the immune system becomes exposed to the highest possible dose of soluble allergen for the maximal duration before swallowing. In contrast, a SLIT-tablet formulation that provides incomplete and slower allergen release will likely require a higher allergen content compared to the more efficient formulation, in order to achieve the same dose of soluble allergen, consequently leading to an excess load of allergen that becomes swallowed without having been made immunologically available.

Prepubertal exposure to glucocorticoid delays puberty independent of the hypothalamic Kiss1-GnRH system in female rats.

Secretion of glucocorticoids is widely known as a key endocrine response to stresses. Prenatal dexamethasone administration induces intrauterine growth retardation and delayed onset of puberty in female rats independent of the hypothalamic Kiss1-gonadotropin-releasing hormone (GnRH) system. The aim of this study was to evaluate the influence of chronic intracerebroventricular (central, CD) or subcutaneous (peripheral, PD) dexamethasone administration to prepubertal female rats on the onset of puberty and body weight change. Rats administered dexamethasone from day 25 to day 34 (CD and PD) showed significantly reduced body weight gain throughout the experimental period and delayed onset of vaginal opening compared with rats administered saline centrally (CS) or peripherally (PS). At 34 days old, hypothalamic Kiss1r mRNA levels were significantly lower with CD than with CS. No significant differences were seen between rats administered saline and rats administered dexamethasone with regard to hypothalamic Kiss1, GnRH and NPY mRNA levels or serum LH levels. Serum leptin concentrations were higher in CD and PD than in the controls (CS and PS). These results suggest that the delayed onset of puberty induced by prepubertal dexamethasone administration occurs independent of the hypothalamic Kiss1-GnRH system.

Effects of lipopolysaccharide exposure at different postnatal time points on the response of LH to homotypic stress in adulthood.

Early-life immune stress may have long-lasting effects, known as programming effects, on the physiological response to stress in adulthood. There may be a critical window after birth during which such a challenge can induce long-lasting alterations. However, there are few reports regarding the consequences of this phenomenon for later reproductive function. Here we report on induction by early-life LPS injection of long-lasting alterations in the adult LH response to homotypic immune stress in male rats. First, we investigated developmental changes in the LH response to LPS, since immune challenge during the stress hyporesponsive period can induce long-lasting effects on physiological functions. Rat serum LH concentrations were decreased by LPS (100 µg/kg) injection on postnatal day 15 or 25, but not day 10, suggesting that the period prior to postnatal day 10 is the stress hyporesponsive period for LH. Serum LH concentrations and body weight were decreased by adult LPS (400 µg/kg) injection in rats given saline or LPS (100 µg/kg) on postnatal day 25, but not in rats given LPS (100 µg/kg) on postnatal day 10. Expression of hypothalamic IL-1ß and TNF-α mRNA, which suppress serum LH during immune stress, were equally increased in these groups by adult LPS (400 µg/kg) injection. The present data suggest that the period prior to postnatal day 10 is the critical window in which immune stress can induce long-lasting alterations in the LH response, but that IL-1ß and TNF-α are not involved in mediating the altered response.

Effect of immune stress on body weight regulation is altered by ovariectomy in female rats.

It has been suggested that obesity and loss of ovarian function alter the inflammatory response to immune stress. Ovariectomized (OVX) rats, which are used as a model of human menopause, exhibit both hyperphagia-induced obesity and gonadal steroid deficiency. To evaluate the effects of ovariectomy on inflammatory responses, we compared the anorectic response to LPS in OVX rats and gonad intact female rats. As leptin and hypothalamic interleukin-1ß (IL1ß) play pivotal roles in the anorectic response to immune stress, these factors were also measured. It was found that the OVX rats exhibited an increased anorectic response to LPS compared with the sham-operated rats. The OVX rats showed higher serum leptin concentrations and a greater increase in hypothalamic IL1ß mRNA expression after LPS injection. In addition, in order to determine whether gonadal steroid deficiency contributes to the changes in the inflammatory responses of OVX rats, we compared responses between OVX rats treated with gonadal steroids and untreated OVX rats. There were no differences in appetite, the serum leptin level, and hypothalamic IL1ß mRNA expression between the two groups after LPS injection. These findings suggest that the loss of ovarian function increases the induction of leptin and hypothalamic IL1ß synthesis and consequently increases the anorectic response under immune stress conditions. It is possible that these alterations are caused by OVX-induced obesity rather than the direct effects of gonadal steroid deficiency.

Changes in responsiveness of appetite, leptin and hypothalamic IL-1ß and TNF-α to lipopolysaccharide in developing rats.

In addition to its role as a regulator of energy homeostasis, leptin plays a pivotal role in some immune/inflammatory responses. Synthesis and secretion of leptin are increased under immune stress conditions, and increased leptin may participate in the development of anorexia and fever. These actions are partially mediated by up-regulation of hypothalamic IL-1ß. Leptin also protects against immune stress-induced lethality. On the other hand, the response and roles of leptin to immune stress conditions in the neonatal period have scarcely been examined. We hypothesized that 1. the response of leptin to immune stress would be suppressed in the early neonatal period, 2. hyporesponse of leptin in the early neonatal period would attenuate the anorectic response and increase the lethal rate under immune stress conditions and 3. supplementation of leptin in the early neonatal period would increase the anorectic response, whereas it would decrease the lethal rate under immune stress conditions. To test these hypotheses, we first examined the developmental changes in the responses of leptin and hypothalamic proinflammatory cytokines, i.e., IL-1ß and TNF-α, to LPS-induced immune stress in female rats. We also examined the developmental changes in the anorectic response and lethality rate under LPS-induced immune stress conditions. Five- and 15-day-old rats showed no leptin response and a weak hypothalamic IL-1ß response to LPS when compared with 25- and 42-day-old rats. Fifteen-day-old rats showed low anorectic responses and high lethality rates when compared with 25- and 42-day-old rats under LPS-induced immune stress conditions. We then examined whether administration of leptin affected the response to the anorectic and lethal effects of LPS in 15-day-old rats. Administration of leptin further attenuated body weight after LPS injection, but not after saline injection. On the other hand, administration of leptin did not affect survival rate. In addition, hypothalamic IL-1ß mRNA levels were not affected by leptin administration. In conclusion, the absence of a leptin response may act to prevent immune stress-induced anorexia during the early neonatal period.

Changes in the responsiveness of serum leptin and hypothalamic neuropeptide Y mRNA levels to food deprivation in developing rats.

Neuropeptide Y (NPY) is an important orexigenic peptide that acts in the brain. The increase in hypothalamic NPY mRNA expression induced by fasting is mainly caused by a decrease in the effects of leptin. We investigated the developmental changes in the sensitivities of leptin and hypothalamic neuropeptide Y to fasting. Hypothalamic NPY mRNA levels were increased by fasting in postnatal days 15 and 25 rats, but not in postnatal day 5 rats. Serum leptin levels were decreased by fasting in rats at all ages (days 5, 15, and 25). In addition, hypothalamic OB-Rb mRNA levels were decreased by fasting in postnatal day 25 rats, but not in postnatal day 5 or 15 rats. Although the percentage of fating-induced decrease in the serum leptin level was larger in the postnatal day 15 rats than in the postnatal day 25 rats, the percentage of increase in the hypothalamic NPY mRNA level in the postnatal day 15 rats was smaller than that in the postnatal day 25 rats. There was a strong inverse correlation between serum leptin levels and hypothalamic NPY mRNA levels in the postnatal day 25 rats, whereas no significant correlation was found between these parameters in the postnatal day 5 or 15 rats. These findings indicate that the sensitivity of hypothalamic NPY mRNA expression to food deprivation and hypoleptinemia has developed by postnatal day 25.