Food restriction-mediated adrenal influences on antigen-induced bronchoconstriction and airway eosinophil influx in the guinea pig

Fasting mitigates immediate hypersensitivity: a pivotal role of endogenous D-beta-hydroxybutyrate

Background

Fasting is a rigorous type of dietary restriction that is associate with a number of health benefits. During fasting, ketone bodies significantly increase in blood and become major body fuels, thereby sparing glucose. In the present study, we investigated effects of fasting on hypersensitivity. In addition, we also investigated the possible role of D-beta-hydroxybutyrate provoked by fasting in the attenuation of immediate hypersensitivity by fasting.

Methods

Effects of fasting on systemic anaphylaxis were examined using rat model of toluene 2, 4-diisocyanate induced nasal allergy. In addition to food restriction, a ketogenic high-fat and low-carbohydrate diet that accelerates fatty acid oxidation and systemic instillation of D-beta-hydroxybutyrate were employed to elevate internal D-beta-hydroxybutyrate concentration. We assessed relationship between degranulation of rat peritoneal mast cells and internal D-beta-hydroxybutyrate concentration in each treatment. Changes in [Ca²⁺]i responses to compound 48/80 were analyzed in fura 2-loaded rat peritoneal mast cells derived from the ketogenic diet and fasting.

Results

Immediate hypersensitivity reaction was significantly suppressed by fasting. A significant reduction in mast cells degranulation, induced by mast cell activator compound 48/80, was observed in rat peritoneal mast cells delivered from the 24 hours fasting treatment. In addition, mast cells delivered from a ketogenic diet and D-beta-hydroxybutyrate infusion treatment also had reduced mast cell degranulation and systemic D-beta-hydroxybutyrate concentrations were elevated to similar extent as the fasting state. The peak increase in [Ca²⁺]i was significantly lower in the ketogenic diet and fasting group than that in the control diet group.

Conclusions

The results of the present study demonstrates that fasting suppress hypersensitivity reaction, and indicate that increased level of D-beta-hydroxybutyrate by fasting plays an important role, via the stabilization of mast cells, in suppression of hypersensitivity reaction.

Comet assay to determine DNA damage induced by food deprivation in rats

The aim of this work was to evaluate, by comet assay, the possible inducing of DNA lesions in peripheral blood mononuclear cells of rats subjected to acute or chronic food deprivation. Wistar male rats were subjected to 72 h of partial (50%), or total acute food deprivation, and then allowed to recover for different time periods (24, 48 and 72 h). In other experiments, comet scores were determined in peripheral blood mononuclear cells of rats subjected to chronic food deprivation (25% and 50%) for 50 days. Blood aliquots were obtained before, during and after food deprivation. Comet assay was carried out, the comet units photographed and scored (class 0 up to 3). Acute and chronic food-deprived rats presented peripheral blood mononuclear cells with DNA lesions (comet classes 1, 2 and 3) and a significant increase (p<0.05) in the number of comet units compared with its basal level. The increase was proportional to acute food deprivation time, but after being taken off, it progressively returned to basal level after 48 h (partial group) or 72 h (total group). Chronic food-deprived rats presented a progressive increase of comet score up to 5 days, and a decrease thereafter to reach a basal level. Possible mechanisms of DNA lesions are discussed.

Fasting stress exacerbates classical conditioned histamine release in guinea pigs

To clarify the contribution of stress to classical conditioning-associated asthmatic responses, the effect of fasting stress on conditioned histamine release was investigated in a guinea pig model of asthma. The animals were randomly divided into 2 groups for Experiment 1 and 2, and received a conditioning procedure in which ovalbumin (OA) as an unconditioned stimulus (US) and dimethylsulfide (DMS, sulfur smelling) as a conditioned stimulus (CS) were simultaneously inhaled after fasting for 16 h. Then, one group was given food as a reward for respiratory distress, and the other group was denied it for more than 3 h, while being placed in front of the feeding group. After this procedure was repeated 5 times, the plasma histamine levels in response to the CS were measured in half of each group in Experiment 1, and the respiratory resistance (Rrs) was assessed similarly in the other half of each group in Experiment 2. The same experiments were again performed after exchanging assignments of feeding group or fasting group in both experiments. The control groups in both experiments received the CS and the US 10 times separately in a random order under 16 h fasting conditions and were provided food after the exposures. After these pseudo-conditioning presentations, the plasma histamine levels or the Rrs in response to the CS were measured. In Experiment 1, the plasma histamine levels in the fasting stress group after the first conditioning sessions were significantly higher than those of the other groups. This difference was not observed when the groups were exchanged. In Experiment 2, the fasting stress group showed higher values in the Rrs compared to the other groups, irrespective of the first or second conditionings; however, they were not significant. The present study indicates that fasting stress after the conditioning procedures exacerbates the following conditioned histamine release, although the stress effect on bronchoconstriction was not confirmed.

Effects of triamcinolone acetonide on adult human lung fibroblasts: decrease in proliferation, surface molecule expression and mediator release

BACKGROUND

Lung fibroblasts may have a pivotal role in airway inflammation as they are involved in continuous cycles of mediator secretion, proliferation, activation and cross-talk with recruited inflammatory cells. The role of fibroblasts as intermediate participants in the inflammatory network suggests that they could represent an important target for drugs commonly used in asthma; thus, we investigated the effects of triamcinolone acetonide (TAA) on primary human lung fibroblasts.

METHODS

The in vitro activity of increasing concentrations (10(-9) to 10(-7) M) of TAA in fibroblast cultures was evaluated as regards the following parameters: proliferation, extracellular matrix (ECM) release, cytokine/chemokine secretion and surface antigen expression.

RESULTS

All concentrations of TAA decreased fetal calf serum (FCS)-induced fibroblast proliferation, whereas in the presence of FCS plus basic fibroblast growth factor TAA was only effective at 10(-8) and 10(-7) M. TAA failed to decrease ECM, whereas at 10(-8) and 10(-7) M it decreased IL-6 and IL-8 secretion to different extents. In the presence of IFN-gamma the drug was able to reduce VCAM-1 expression at all of the tested concentrations; on the other hand, in TGF-beta 1-driven cultures a decrease in CD54 expression was detected with TAA at 10(-8) and 10(-7) M.

CONCLUSIONS

TAA acts on some functional properties of human lung fibroblasts that make these cells active participants in the inflammatory network. The ability of TAA to inhibit lung fibroblast proliferation may prevent or even reverse some of the histological changes that characterize airway remodeling in chronic inflammatory diseases; moreover, IL-6, IL-8 and surface molecule decreases by TAA may suggest a direct anti-inflammatory effect of the drug by suppression of resident lung cell function.

Fluticasone propionate downregulates nasal fibroblast functions involved in airway inflammation and remodeling

BACKGROUND

Besides being highly effective in the treatment of allergic and nonallergic rhinitis with eosinophilia, intranasal corticosteroids appear to be useful in reducing nasal polypoid lesions and the likelihood of polyp recurrence after surgery. We evaluated the ability of fluticasone propionate to downregulate fibroblast functions related to nasal inflammation and remodeling.

METHODS

Primary nasal polyp tissue-derived fibroblasts were stimulated with tumor necrosis factor (TNF)-alpha or interleukin (IL)-4 or basic fibroblast growth factor (bFGF) in the presence of fluticasone propionate (0.1-100 nM). Fibroblast proliferation, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression and eotaxin release were then evaluated.

RESULTS

As compared with unstimulated cultures, a significant increase in fibroblast proliferation was observed when the cells were stimulated with bFGF (p < 0.05), but not with TNF-alpha or IL-4 (p > 0.05). TNF-alpha induced an upregulation of ICAM-1 expression (p < 0.05), which was not seen in fibroblasts cultured in the presence of IL-4 or bFGF. No changes in VCAM-1 expression were induced by TNF-alpha, IL-4 or bFGF, whereas both TNF-alpha and IL-4 increased eotaxin release (p < 0.05). Both bFGF-induced fibroblast proliferation and TNF-alpha-induced ICAM-1 expression were significantly reduced by fluticasone, starting at the dose of 1 and 10 nM, respectively (p < 0.05). Fluticasone at concentrations of 1-100 nM effectively inhibited eotaxin release by TNF-alpha- or IL-4-stimulated fibroblasts (p < 0.05).

CONCLUSIONS

The pharmacologic activity of fluticasone in patients with chronic upper airway inflammatory disease may include inhibition of resident fibroblast functions involved in airway inflammation and remodeling.

Neuroendocrine consequences of very early weaning in swine

An experiment was conducted to investigate the consequences of very early weaning of piglets on neuroendocrine variables and growth. Sixty piglets from eight litters were either weaned on Postnatal Day 6 (early weaning, or EW piglets) or left with their dam until normal weaning at Day 28 (control piglets, or C). At Days 5, 7, 11, 14, and 19, urine was collected between 7:00 and 8:00 a.m. for the measurement of catecholamines, glucocorticoids, and creatinine. Compared with C, EW piglets displayed a transient increase in urinary cortisol on the day following separation from their dam (Day 7) (P<.05). Urinary norepinephrine (NE) was three times lower in EW compared to C piglets from Day 7 until Day 14 (P<.01) but there was no difference between the two groups on Day 19. Urinary epinephrine (EPI) did not differ between C and EW piglets on the day after weaning. Thereafter, EW piglets displayed a three times drop in urinary EPI as compared to C piglets until the end of the period (P<.01). Weaning induced an immediate reduction in food intake and growth rate and at Day 28, the body weight of EW piglets was 1.60 kg lower than that of C piglets (P<.0001). In conclusion, weaning of 6-day-old piglets results in a marked and prolonged suppression of the release of catecholamines. This result likely reflects physiological responses to insufficient energy intake after weaning, as reflected also by changes in thermoregulatory behavior. The transient increase in cortisol excretion in weanlings may be caused by both emotional distress and acute food deprivation.