ABSTRACT
Objective To investigate the expression of pattern recognition receptor (PRR)of immune cells from the patients with enterovirus 71 ( EV 71 ) infection and the changes of cytokines. Methods Seventy-one patients and 20 age-matched healthy children were enrolled in the study. The patients were divided into three groups according to the critical degree: 20 mild patients, 25 severe patients and 26 critical patients. Real-time PCR were used to evaluate the levels of retinoic acidinducible gene Ⅰ ( RIG- Ⅰ ), melanoma differentitation-associated gene 5 ( MDA5 ) and cytokines IL-12, IFN-α mRNA expression in peripheral blood mononuclear cells (PBMC). The proportions of Toll like receptors(TLRs) on monocytes/macrophages (MC) , myloiddentritic cells (mDC) and plasmacytoiddentritic cells (pDC) were analyzed by flow cytometry. The concentrations of plasma cytokines( IL-12, IFN-α) were measured by ELISA. Results ( 1 ) The proportion of TLR7 is the unique TLR which is increased in mild patients and it was significantly elevated in MC, mDC and pDC in severe group (P＜0.05), TLR2, TLR3 and TLR4 also had an enhanced expression in MC and mDC. The enhanced expression of TLRs mentioned above had a decreased trend in critical patients. (2)Transcription levels of RIG- Ⅰ and MDA5 was significantly elevated in EV71 infected children.(3)The expression levels of DC-associated cytokines gene( IL-12 and IFN-α) have an increased trend in mild cases and these cytokines were remarkably increased in severe patients (P＜0.05), whereas decreased in critical cases (P＜0.05). ConclusionTLR7 might be the main PRR recognizing EV71 in immune cells and RIG-Ⅰ/MDA5 might also take part in the recognition of EV71. The exogenous or endogenous ligands released from bacterial infection and cell destruction could result in the activation of TLR2 or TLR4, inducing the inflammatory response.