engleski

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

Toll-like receptors (TLRs) are part of the innate immune system able to recognize pathogen-associated molecular patterns and activate immune system upon pathogen challenge. TLR7 and TLR8 recognize single-stranded viral RNA and initiate antiviral control mechanisms. RNA virus particularly detrimental in infancy is respiratory syncytial virus (RSV). RSV can cause severe lower respiratory tract disease and recurrent infections related to inadequate development of anti-viral immunity. The reason for frequent RSV re-infections in infancy could be inadequate TLR7 and TLR8 engagement by viral RNA resulting in lower synthesis of anti-inflammatory mediators and antigen presentation, possibly due to a lower TLR expression in peripheral blood mononuclear cells (PBMC) of a still developing immune system. We determined TLR7 and TLR8 expression in PBMC subsets from infants with primary RSV infection and their healthy controls using multi-parameter flow cytometry. We found the expression of TLR7 and TLR8 in monocytes is lower in infected infants than in healthy controls. Also, the comparison of TLR7 and TLR8 expression between different age groups revealed that they are expressed at lower level in monocytes from infants (both diseased and healthy) when compared to healthy adults and newborns. Unexpectedly, TLR8 in T cells and NK cells was detected in lower percentage in infected infants when compared with healthy controls. Difference in percentage of both cell subsets positive for TLR8 between healthy and infected infants emphasize possible role in mounting anti-RSV immunoreactions. In conclusion, difference in TLR7 and TLR8 expression stresses out their importance in early antiviral immune mechanisms responsible for the control of RSV replication and generation of an adaptive immune response.

Toll-like receptors; TLRs; TLR7; TLR8; RSV

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