1,25-Dihydroxyvitamin D3 potentiates the decreased response of lymphocytes from atopic subjects to agents that increase intracellular cyclic adenosine monophosphate

Serum 25-hydroxyvitamin D3 levels in children with allergic or nonallergic rhinitis

OBJECTIVES

The relationship between vitamin D and allergic diseases such as asthma and atopic dermatitis is shown in several studies. But there is a lack of knowledge about vitamin D status in children with allergic rhinitis (AR). We aimed to investigate serum vitamin D levels of children with AR or nonallergic rhinitis (NAR), to compare with normal subjects and to evaluate the relationship between vitamin D and the severity of AR.

METHODS

The study included a total of 141 children (76 patients with rhinitis and 65 control subjects), who applied to the Pediatric allergy immunology outpatient. Skin prick tests were performed using the same antigens for all patients. Serum 25-hydroxyvitamin D3 (25OHD3) levels were measured. AR was classified according to the ARIA guidelines.

RESULTS

Mean 25OHD3 levels were 18.07±6.1ng/mL in the AR group, 14.81±4.86 in the NAR, and 24.03±9.43ng/mL in the control group. These differences among groups were statistically significant (p=0.001). Vitamin D status was determined as deficient in 32 (66.7%) patients, insufficient in 14 (29.2%) and normal in 2 (4.2%) of the AR group. These frequencies for NAR and control groups are 25 (89.3%), 3 (10.7%), 0, and 25 (38.5%), 32 (49.2%), 8 (12.3%), respectively. Vitamin D status was found to be different among groups (p=0.001). There were not any association between 25OHD3 levels and allergen sensitivity (p>0.05). The comparison of the mean 25OHD3 levels according to the severity and duration of AR did not detect statistically significant difference among groups (respectively, p=0.384, p=0.23 Denburg J, Fokkens WJ, Togias A5).

CONCLUSIONS

The mean serum 25OHD3 levels of the children both with AR and NAR were lower than control group. No association between 25OHD3 levels and allergen sensitivities was found in our study. We did not find any relationship between 25OHD3 levels and the severity and duration of allergic rhinitis.

Defect in potentiation of adenylyl cyclase correlates with bronchial hyperreactivity

BACKGROUND

Adenylyl cyclase is a transmembrane signaling system involved in the inhibition of cellular responses. Recently, we showed that the activity of adenylyl cyclase may be potentiated by stimuli that induce an increase of cellular responses but that do not activate adenylyl cyclase. This is probably an important physiologic feedback mechanism that prevents cells from becoming "overstimulated."

OBJECTIVE

Because increased cellular activities are frequently observed in persons with asthma, we hypothesized that a defect in potentiation of adenylyl cyclase might be involved.

METHODS

Potentiation of isoprenaline-induced adenosine cyclic monophosphate (cAMP) production with the mitogen phytohemagglutin (PHA; 45 micrograms/ml) or the calcium ionophore A23187 (1 mumol/L) was studied in peripheral blood mononuclear cells taken from patients with asthma (n = 8) and healthy control subjects (n = 11).

RESULTS

Isoprenaline-induced cAMP production was potentiated significantly in the healthy control subjects (PHA, 110% +/- 15%; A23187, 92% +/- 25%). In contrast, potentiation was not seen with PHA or A23187 in the total group of patients with asthma. However, some patients showed weak potentiation, whereas in others PHA decreased isoprenaline-induced cAMP production. Moreover, the effect of PHA on isoprenaline-induced cAMP production correlated significantly with the degree of bronchial hyperreactivity in patients with asthma (r = 0.96; p = 0.0001).

CONCLUSIONS

The observed defect in signal transduction could play an important part in bronchial hyperresponsiveness.