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Chemokines and their receptors in BAL samples of infants with respiratory infections

Virtually all infants experience respiratory syncytial virus (RSV) infection by their second year of life. Some of them are hospitalized due to development of severe form of illness (bronchiolitis). This is often accompanied by mucus and cell debris accumulation in the lungs which closes airways and unable proper breathing and results in higher respiratory frequency and lower blood oxygen saturation. In those cases bronchoscopy and bronchoalveolar lavage (BAL) collecting is made as a therapeutic procedure that should help to clean airways and allow patients to breathe more easily. RSV infects lung epithelial cells causing local secretion of proinflammatory cytokines and chemokines (such as IL-8, RANTES, IP-10, MIG, TARC, MDC). Chemokines are responsible for the recruitment of different lymphocyte populations via chemokine receptors implicating their role in diseases resolution or exaggeration of the immune response. Moreover certain chemokines could be related to the type of adaptive immune response (Th1/Th2) determining disease pathology. In order to complete our previous results of systemic chemokine/chemokine receptor profile in acute RSV infection, we have tested collected BAL samples for chemokine concentrations (IP-10, MIG, MDC, TARC, fractalkine) by commercially available ELISAs. Isolated BAL cells enriched for lymphocyte subsets by adhesion, lymphocyte subpopulations were immunostained for chemokine receptor expression. RSV infection predominantly induces secretion of IP-10/MIG in the airways which is necessary for efficient viral clearance. Moreover this chemokines are typically related to beneficial Th1 immune response but also could mount disease severity. TARC/MDC levels were below test sensitivity. This chemokines are connected to Th2 immune response, but also seems to have protective role during RSV infection.

RSV; chemokine; BAL; infants; IP-10; TARC; CD8 T cells; CXCR3; CX3CR1; CCR4

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