Changes Of Cellular Immune Function And Toll-like Receptors Of Peripheral Blood Mononuclear Cells In Patients With Enterovirus71Infection

ObjectivesThe present study was initiated to explore the potential involvement of the cellularimmune function and Toll-like receptors signaling pathway in children with enterovirus71infection(EV71) by studying the expression of the Toll-like receptor3、4、7mRNA inperipheral blood mononuclear cells(PBMCs) and cellular immune function of EV71-infected children. Our study would shed novel light on the underlying mechanism ofEV71infection.MethodsPart1Fifty-five EV71-infected children were enrolled in this study. The children weredivided into three groups according to critical degree of EV71infection：25mild cases,20severe cases， and10critical cases. The clinical data was analyzed, and flow cytometrywas used to analyze the number of B cells, T cell subsets, and NK cells in peripheralblood. Part2Using reverse transcription-polymerase chain reaction(RT-PCR), we examinedthe expression levels of TLR3、TLR4、TLR7mRNA in PBMCs in55EV71-infectedchildren and18controls (age-matched healthy children). The amplification of β-actinmRNA was served as internal control. Results in terms of specific targets expression levelsfor each sample were normalized to those of the internal control β-actin. Using ELISA, weexamined the expression levels of cytokines IL-6, IL-10, TNF-α in EV71-infected childrenand the children in normal control group.Results1. Clinical Data Analysis:55cases of EV71-infected children including mild group of20cases,11males and9females; severe group of25cases,9males and16females;critical group of10cases,6males and4females. No significant difference among thosethree groups in ages (p>0.05).4cases of children in severe group have acute flaccidparalysis. All of children in mild group and severe group were recovery. Due to brainstemencephalitis, neurogenic pulmonary edema, or respiratory failure,6cases of children incritical group were carried out mechanical ventilation,3cases died and1case give up thetreatment,6cases were recovery. The duration of fever before admission had nodifference among those three groups (F=2.39, p>0.05). The peak temperature of criticalgroup is higher than the mild group (p>0.05). The number of white blood cells, bloodsugar, neutrophils, platelets were remarkably increased in critical group of children（p<0.05）.2. The number of peripheral blood T cell subsets, NK cells, and B cells: The number ofperipheral blood T-cell subsets including CD3、 CD4、 CD8T cells in the children ofsevere group and the critical group showed significantly decreased. The number of CD3、CD4T cells and NK cells in children of critical group were statistically different to thechildren of mild group and severe group (p <0.05). The number of B cells was nosignificant difference among those groups.3. Toll-like receptor expression: The expression of PBMC TLR4、TLR7mRNA inEV71-infected children more higher than the children in normal control group. Theexpression of TLR3mRNA in children of mild group is the highest than the children of normal control group, severe group, and critical group (p <0.05). Compared with thechildren of normal control group and severe group，the expression of TLR3mRNA inchildren of critical group was significantly decreased (p <0.05). The expression of TLR7mRNA in children of severe group was higher than the children of critical group(p <0.05).4. Changes in the levels of cytokines: Compared with the children in normal controlgroup，mild group and severe group，the study found that the level of IL-6in peripheralblood of the children in critical group was the highest (p <0.05). Compared with thechildren in normal control group， mild group and severe group， the level ofanti-inflammatory cytokine IL-10in peripheral blood of the children in critical group wasthe highest (p <0.05). Compared with the children in normal control group，the level ofpro-inflammatory cytokine TNF-α in mild group and severe group were more higher (p<0.05). Compared with the children in normal control group，mild group and severegroup，the value of IL-10/TNF-α in the children in critical group was the highest (p<0.05).Conclusion1. The number of CD3+, CD4+T lymphocyte and NK cells decreased significantly inthe children of critical group. The number of B lymphocytes showed no significantdifference among those groups.2. The expression of TLR3mRNA declined in the children of critical group. Theexpression of TLR4, TLR7mRNA is significantly increased in the children of severegroup. The abnormal activation of TLRs as one of the factors which lead to differentcritical degree of infection may be involved in the pathogenic mechanisms of EV71.3. The level of IL-6, IL-10in peripheral blood plasma of EV71-infected children wassignificantly higher. The level of TNF-α in peripheral blood plasma of the children incritical group was significantly decreased. The study showed that the change of cytokineswas correlated with the outcome of EV71infection...