Rhinovirus infection and house dust mite exposure synergize in inducing bronchial epithelial cell interleukin-8 release.

BACKGROUND: Human rhinoviruses (HRVs) and house dust mites (HDMs) are among the most common environmental factors able to induce airway inflammation in asthma. Although epidemiological studies suggest that they also synergize in inducing asthma exacerbations, there is no experimental evidence to support this, nor any information on the possible mechanisms involved. OBJECTIVE: To investigate their interaction on the induction of airway epithelial inflammatory responses in vitro. METHODS: BEAS-2B cells were exposed to activated HDM Dermatophagoides pteronyssinus major allergen I (Der p I), HRVs (HRV1b or HRV16) or both in different sequences. IL-8/CXCL8 release, intercellular adhesion molecule (ICAM)-1 surface expression and nuclear factor kappaB (NF-kappaB) translocation were evaluated. Complementary, primary human bronchial epithelial cells (HBECs) exposed to both Der p I and RVs and IL-8, IL-6, IFN-gamma-induced protein (IP)-10/CXCL10, IFN-lambda1/IL-29, regulated upon activation normal T lymphocyte expressed and secreted (RANTES)/CCL5 release were measured. RESULTS: RV and Der p I up-regulated IL-8 release, ICAM-1 expression and NF-kappaB translocation in BEAS-2B cells. Simultaneous exposure to both factors, as well as when cells were initially exposed to HRV and then to Der p I, resulted in further induction of IL-8 in a synergistic manner. Synergism was not observed when cells were initially exposed to Der p I and then to HRV. This was the pattern in ICAM-1 induction although the phenomenon was not synergistic. Concurrent exposure induced an early synergistic NF-kappaB translocation induction, differentiating with time, partly explaining the above observation. In HBECs, both HRV and Der p I induced IL-8, IL-6, IL-29 and IP-10, while RANTES was induced only by HRV. Synergistic induction was observed only in IL-8. CONCLUSION: HRV and enzymatically active Der p I can act synergistically in the induction of bronchial epithelial IL-8 release, when HRV infection precedes or is concurrent with Der p I exposure. Such a synergy may represent an important mechanism in virus-induced asthma exacerbations.

Modulation of the epithelial inflammatory response to rhinovirus in an atopic environment.

BACKGROUND: Immune responses to rhinovirus (RV) as well as direct effects of RV on respiratory epithelium may contribute to the induction of asthma exacerbations. OBJECTIVE: To evaluate the effect of the environment resulting from an atopic immune response on RV-induced epithelial inflammation, replication and cytotoxicity. METHODS: Peripheral blood mononuclear cells (PBMC) from atopic asthmatic subjects and matched controls (12 pairs) were isolated and stimulated by RVs. Human bronchial epithelial (BEAS-2B) cells were infected with RV in the presence of conditioned media from RV-stimulated PBMC cultures. IL-6, IL-8, RANTES and TGF-beta1 levels were measured by ELISA, RV-induced cytotoxicity by a colorimetric method and RV titres on Ohio-HeLa cells. RESULTS: RV-induced epithelial production of IL-6, IL-8 and RANTES was significantly lower, while TGF-beta1 was higher when cells were exposed to conditioned media from atopic asthmatic subjects compared with those from normal controls. Exposure to the 'atopic' environment also resulted in elevated RV titres and increased RV-induced cytotoxicity. CONCLUSIONS: Under the influence of an atopic environment, the epithelial inflammatory response to RV is down-regulated, associated with increased viral proliferation and augmented cell damage, while TGF is up-regulated. These changes may help explain the propensity of atopic asthmatic individuals to develop lower airway symptoms after respiratory infections and indicate a mechanism through which viral infections may promote airway remodelling.

Hospitalizations for childhood asthma in Athens, Greece, from 1978 to 2000.

Trends in rates of asthma admissions among children have shown a variety of patterns in different countries in the last decades. We undertook the present study to determine the time trends in asthma admissions and readmissions of children in Athens, Greece. Data were obtained retrospectively from hospital registries of the three main children's hospitals in Athens from 1978 to 2000. Children admitted with the diagnoses of asthma, asthmatic bronchitis or wheezy bronchitis were included. Hospital admission rate for asthma among children 0-14 yr from 1978 to 2000 rose by 271% (p <0.001). The rise in rates among those aged 0-4 and 5-15 yr were 250% and 276%, respectively. The mean annual increase in admission rate was 12.2% for 1978-1987, 4.7% for 1988-1993 and 0.6% for 1994-2000. The readmission rate among children 0-14 yr was increased from 15.3% to 23.3%. A positive correlation between admission and readmission rates in all age groups was observed. In conclusion, our findings show an increase in the childhood asthma admission rate in Athens in late 1970's and during the 1980's, which has decelerated in the 1990's, particularly in the second-half of the decade. The readmission rate paralleled that of admissions over the entire study period.

Expression of costimulatory molecules in peripheral blood mononuclear cells of atopic asthmatic children during virus-induced asthma exacerbations.

BACKGROUND: Respiratory viruses are the most frequent triggers of acute asthma exacerbations. Herein we investigate costimulatory molecule expression on peripheral blood mononuclear cells (PBMC) during such exacerbations. METHODS: Eleven children with atopic asthma were followed prospectively and respiratory symptoms were recorded on diary cards. A blood sample and nasopharyngeal wash (NPW) were obtained at baseline and subsequently during an exacerbation. PBMC were immunophenotyped using flow cytometry. NPW samples were examined for the presence of respiratory viruses by RT-PCR. RESULTS: A virus was detected in 73% of exacerbations and none at baseline. A drop of NK cells and a marginal increase of monocytes were the only changes of cell count during the exacerbation. A significant downregulation of B7-2 on NK cells and of B7-1 on monocytes was also observed during exacerbations. CONCLUSIONS: The above observations are in contrast to in vitro findings showing an upregulation of costimulatory molecules after exposure of blood cells to viruses or allergens. It is possible that activated immune cells leave the blood stream to migrate to the inflammation site during acute asthma exacerbations.

Correlation of lymphocyte proliferating cell nuclear antigen expression with dietary cow's milk antigen load in infants with allergy to cow's milk.

BACKGROUND: Controversial results have been reported on the participation and diagnostic value of lymphocyte reactivity in cow's milk (CM) allergy. In this study, we used a specific nuclear marker to evaluate lymphocyte proliferation in IgE-mediated CM allergy in infants, and examine its relation with diets containing different CM antigen loads. METHODS: Infants with IgE-mediated CM allergy, as assessed by open provocation and RAST, were grouped according to their exclusive diet, either CM formulae, breast feeding, or hydrolysed whey formulae. A group of non-atopic infants receiving CM was also examined. Lymphocyte proliferation to beta-lactoglobulin was evaluated by quantitation of the proliferating cell nuclear antigen (PCNA) expression in peripheral blood mononuclear cells, by flow cytometry. Immunophenotypic surface markers were also examined. RESULTS: A marked difference of PCNA expression between CM-fed allergic infants and healthy controls was observed (p<0.001). In this setting, PCNA expression >/=10% was highly specific and sensitive as a marker of CM allergy in CM-fed infants. Moreover, a significant correlation (p<0.001) between antigen load and PCNA was established in CM-allergic infants under different diets, higher values obtained with increasing antigen loads. In addition, within the group fed hydrolyzed formulae, low-molecular-weight products resulted in marginally lower PCNA expression than higher-molecular-weight formulae. No differences in immunophenotype were found, with the exception of a higher CD23 expression in the breast-fed group. CONCLUSIONS: PCNA could be a useful marker in the assessment of lymphocyte proliferation to CM antigens. Low CM antigen diets are related with reduced lymphocyte reactivity, which may partly explain the clinical benefit observed with such diets.

Interferon-gamma pretreatment of peripheral blood mononuclear cells partially restores defective cytokine production in children with atopic dermatitis.

Interferon-gamma (IFN-gamma) is considered an important determinant of the balance between T-helper type 1 and 2 cytokines and has been used experimentally for the treatment of atopic dermatitis. However, contrasting results have been reported relative to the Th-1/Th-2 cytokine profile in atopic patients. In this study, we examined cytokine production by polyclonally activated peripheral blood mononuclear cells (PBMC) from children with atopic dermatitis, and assessed the influence of in vitro IFN-gamma pretreatment on these cells. A fraction of PBMC isolated from children with severe atopic dermatitis, as well as from age-matched controls, was initially exposed to IFN-gamma. After washing, both treated and untreated cells were then put into culture either alone or with the addition of phytohemagglutinin (PHA) or phorbol myristate acetate (PMA) plus ionomycin. IL-4, IL-5, IL-10 and IFN-gamma production were measured in the supernatants using commercially available ELISAs. PBMC from atopic patients produced more IL-4 (P = 0.04) and IL-10 (P = 0.03) and less IFN-gamma (P = 0.01) than controls, when stimulated with PHA. Interestingly, in PMA + ionomycin stimulated cultures, the atopic cytokine profile was different with more IL-5 (P = 0.0068) and less IFN-gamma production (P = 0.00046) than the control group. When cells were pretreated with IFN-gamma, there were no significant differences between patients and controls. PBMC from children with atopic dermatitis show alterations in cytokine production, compatible in general terms with the Th-1/Th-2 model. Exposure of PBMC to IFN-gamma before activation results in a reduction of these differences, so that cytokine production becomes similar in the atopic and normal groups.

Time trends and seasonal variation in hospital admissions for childhood asthma in the Athens region of Greece: 1978-88.

BACKGROUND: The aim of the study was to determine the trend and seasonal variation in hospital admissions for childhood asthma in the Athens region of Greece. METHODS: Data were obtained from hospital registries of the three main children's hospitals in Athens between 1978 and 1988. Children admitted with the diagnosis of asthma, asthmatic bronchitis, or wheezy bronchitis were included. The data were expressed as admission rates per 100,000 of the same aged population. RESULTS: There were 9795 admissions for asthma over the 11 years and the admission rate rose by 294%. Admissions among those aged 0-4 and 5-14 rose by 272% and 379% respectively. Monthly admissions showed a pronounced seasonal variation, rising during the cold damp period in the 0-4 age group, but peaking around May in the 5-14 age group. CONCLUSIONS: These findings suggest that hospital admissions due to asthma in the Athens region have increased considerably since 1978, and that clear cut seasonal variations exist which are specific to age.

Sensitization of asthmatic children to common environmental allergens according to their residence.

The medical records of 974 asthmatic children aged 1-14 years (mean 8.7 +/- 3.9 years) who had been evaluated with skin prick tests (SPT) in two referral Children's Hospitals in Athens from 1975 to 1987 were analyzed. The children were grouped according to their residence into groups from urban area (UR), rural area (RU), and coastals (CO). The prevalence of positive SPT and the sensitizing allergens according to the residential area and the family atopic history were considered. It was found that 662/974 (68%) children had positive SPT with 63.6%, 70.7%, and 80.4% in UR, RU, and CO respectively. There was a significant difference in the prevalence of positive SPT between UR and CO. A positive family atopic history was more often accompanied by positive SPT in UR only. Sensitization to grass pollens was noted with higher prevalence in UR. The house dust mite Dermatophagoides pteronyssinus sensitization was more prevalent in CO. Our results support the notion that the environment can influence the prevalence of sensitization to common environmental antigens, the kind of sensitizing allergen, and the expressiveness of the genetic factor with regard to development of atopic asthma.

Sister chromatid exchanges in peripheral lymphocytes of children vaccinated against rubella and measles-mumps-rubella.

This study was undertaken in order to evaluate the cytogenetic and immunological responses to the effective, harmless and world-wide used vaccines of I. rubella and II. measles-mumps-rubella (M-M-RII). In one group (A) of five girls vaccinated against rubella and in another group (B) of four boys and two girls vaccinated against measles-mumps-rubella, the following parameters were studied before and repeatedly after vaccination: (a) SCE frequency, in peripheral lymphocytes, (b) DNA-synthesis, in peripheral mononuclear cells, and (c) antibody titres. The mononuclear cell proliferation rate was elevated between the 3rd and 7th day, preceeding the humoral immunological reactions, which began after the 25th day (group A) and the 28th day (group B). The latter findings coincided with a significant increase of SCE frequency in group A (one child) and in group B (all six children); in no case did the highest SCE/cell ratio exceed the normal value.