http://repub.eur.nl/res/aut/3358/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/3956/ 2005-02-01T00:00:00Z Rhinovirus and respiratory syncytial virus (RSV) are the most prevalent inducers of upper respiratory tract infections (URTI) in infants and may stimulate immune maturation. To estimate the amount of immune stimulation, nasal immune responses were examined during rhinovirus and RSV-induced URTI in infants. Nasal brush samples were taken from infants (2-26 months; 57% atopic family) with rhinovirus-induced URTI (N=20), with RSV-induced URTI (N=7), and with rhinovirus-induced rhinitis (N=11), from children with asymptomatic rhinovirus infection (N=7) and from eight non-infected children. Numbers of nasal brush cells positive for Th1-, Th2-, regulatory and proinflammatory cytokines were measured by immunohistochemistry or by measuring protein levels using a cytometric bead array analysis. During rhinovirus and RSV-induced URTI, fewer regulatory cytokine IL-10 positive cells were found compared to non-infected children. This fall was accompanied by an increase in levels of the Th1 cytokine TNFalpha. IL-10 responses were inversely related to TNFalpha responses. No enhanced responses were observed for IFNgamma, IL-12 and IL-18. Cytokine responses were comparable in children with rhinovirus-induced URTI and in children with rhinitis, while responses in asymptomatic rhinovirus-infected children were located between those for symptomatic and asymptomatic rhinovirus-infected children. Cytokine responses did not depend on the age of the child or atopy in the family. In conclusion, reduced nasal IL-10 responses during URTI in infants could facilitate the induction of a TNFalpha response. TNFalpha in turn could replace the immature production of IL-12, IL-18 and IFNgamma during URTI to induce an effective clearance of the viral infection and which could stimulate the maturation of Th1 cytokine production in infancy. http://repub.eur.nl/res/pub/7258/ 2004-01-07T00:00:00Z The human body has an extensive defence mechanism (immune system) for coping with pathogens. It is regulated by signalling molecules called cytokines. Cytokines are produced by various cells of the immune system such as leucocytes (e.g. T-cells and macrophages) but also by nasal and pulmonary epithelial tissue. There are several different types of cytokines. Th1 cytokines are involved in the eradication of bacterial and viral pathogens, while Th2 cytokines are involved in the defence against parasites. The production of Th1 cytokines is suppressed by Th2 cytokines and vice-versa so that the production of both cytokines is kept in balance. An overproduction of Th1 cytokines is found in auto-immune disorders, while allergic disease is frequently accompanied by high Th2 cytokine production. Furthermore, pro-inflammatory cytokines can induce general inflammatory reactions, while anti¬inflammatory and regulatory cytokines may downregulate these responses. Immune responses in newborns are immature. This is seen in relatively high levels of Th2 and regulatory cytokines and low levels of Th1 cytokines compared to adults. The infant immune system matures with age. This maturation process consists of a relative increase in the production of Th1 cytokines compared to Th2 cytokines. Viral respiratory infections in infants may stimulate immune matura¬tion by their repeated Th1 stimulating effect, and thereby reduce the risk of a child developing Th2-mediated allergic disease. This hypothesis was first proposed by Professor Strachan in 1989 and is known as the ’hygiene hypothesis’.In the VI¬GALL study (VIGALL is the Dutch abbreviation for virally-mediated allergy), we examined whether respiratory infections predominantly induced by viruses may affect the maturation of the immune system and the development of allergic dis¬ease. We therefore looked to see which respiratory viruses are most prevalent in infants and what types of immune response are induced in the noses of these chil¬dren during infection and when healthy. We then examined whether the number of respiratory infections and the maturation of the immune system were related. http://repub.eur.nl/res/pub/3913/ 2003-06-01T00:00:00Z Respiratory syncytial virus (RSV) infections are a major cause of severe respiratory disease in infants. It has been shown that there is an increased frequency of childhood wheezing in ex-bronchiolitic preteen children. This was postulated to be mediated by a vigorous virus-specific Th2 response influencing the further development of the immune system. Little is known about the possible role of the immune response to clinically mild RSV infections in this respect. We have studied the RSV-specific cellular immune response in infants with a laboratory-confirmed RSV upper respiratory tract infection (URTI; n = 13, mean age 12 months, range 2-22 months) in comparison with infants with non-RSV mediated URTI (n = 9, mean age 9.3 months, range 4-18 months) or infants with severe RSV bronchiolitis (n = 11, mean age 2.3 months, range 1-6 months). RSV-specific cytokine-producing cells were enumerated using the ELISPOT method in peripheral blood mononuclear cells and nasal brush T-cells, collected during the acute and convalescent phase of the infection. Mixed Th1 (IFN-gamma) and Th2 (IL-4 and IL-13) responses were detected in all three groups. Frequencies of RSV-specific T-cells were lower in both URTI groups than in the RSV bronchiolitis group, and not significantly different between the RSV URTI and the non-RSV URTI group. The absence of vigorous virus-specific Th2 responses upon mild RSV infection does not support the hypothesis that these infections influence the development of the immune system and that they predispose for the development of atopic disease.