engleski

Lower expression of TLR3, TLR7 and TLR8 in PBMC from RSV-infected infants

Innate immunity is important part of immune system with ability to recognize and act (neutralize) upon pathogen challenge. Infants are particularly sensitive to different viral infections with emphasized detrimental effect of respiratory syncytial virus (RSV) induced recurrent infections in infancy related to inadequate anti-viral immunity post-infection. Toll-like receptors (TLRs) are part of the immune system able to recognize and activate immune system upon pathogen challenge. TLR3, 7, 8 recognize genomic viral RNA molecules initiating antiviral control mechanisms. Possible explanation for frequent RSV re-infections in infancy could be inadequate TLR3, 7, 8 engagement in innate immunity responses resulting in lower cytokines synthesis and dendritic cell maturation, due to lower TLRs expression in peripheral blood lymphocytes. In our study specific monoclonal antibodies against human TLR3, 7, 8 molecules were used to determine expression profile of peripheral blood leukocyte subpopulations from healthy and RSV-infected infants by flow cytometry. We have found that RSV-infected infants had lower percentages of TLR3-expressing monocytes, NK cells, T and B cells than healthy controls. Although expression of TLR7 in different leukocyte populations didn’ t statistically differ between healthy and infected infants, a tendency of lower percentages of TLR7 in monocytes, T and B cells was observed. The TLR8, cognate of TLR7 molecule, is expressed on smaller percentage of NK and T cells in RSV infected infants. The comparison of TLR7 and TLR8 expression between different age groups revealed lower expression in monocytes from peripheral blood of infants (diseased and healthy group) than in monocytes from healthy adults and newborns. In conclusion, lower expression of TLR3, 7, 8 stresses out inadequate early antiviral and innate immune mechanisms responsible for the RSV replication control and generating an effective immune response.

RSV; bronchiolytis; Toll-like receptors; pheriperal blood; infants

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