Cerebrospinal Fluid Th1/Th2Cytokine Profiles In Children With Enterovirus71-associated Menningoencephalitis

Background:Enterovirus71(EV71), identified in1969in the United States for the first time, has caused four large-scale epidemic worldwide since them. EV71infection usually causes relatively benigh and self-limited hand, foot and mouth disease (HFMD) and herpangina in children. It can also cause central nervous system (CNS) complications, including aseptic meningitis, encephalitis, brainstem encephalitis (BE), encephalomyelitis, poliomyelitis-like syndrome, pulmonary edema (PE) and even death. The pathogenesis of EV71infection remains unknown. Studies postulated that excessive stimulation of the sympathetic nerve, and increased pulmonary vascular permeability as the result of a systemic inflammatory responses caused by the excessive release of cytokines. Cytokines, which can be secreted by many cells, are small molecule polypeptides and participate in many biological processes, including mediating host innate/adaptive responses, facilitate hematopoiesis and stimulating cell proliferation and differentiation. Meanwhile, cytokines are closely associated with acute inflammation and immune damage during the progression of infectious diseases. Previous studies have shown that PE is associated with extensive inflammatory responses, including significantly elevated levels of cytokines, such as interlukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1β, IL-10, IL-13and interferon (IFN)-y in peripheral blood or cerebrospinal fluid (CSF), as well as the depletion of CD4+T cells and CD8+T cells and natural killer (NK) cells, indicating variance of cytokines plays an important role in the pathogenesis of EV71infection.Objectives:To further elucidate the neuropathogenic mechanism of EV71infection and to confirm the involvement of the cytokines, in the present study, we examined the expression of CSF Thl/Th2cytokines (IL-2, IL-4, IL-6, IL-10, TNF-a and IFN-y) in EV71-related ME patients by cytometric bead array (CBA) technology.Methods:1. The present study was performed at Children’s Hospital, Zhejiang University School of Medicine and Hangzhou Children’s Hospital during the outbreak of HFMD between May2012and August2012.97HFMD patients with meningoencephalitis (ME) confirmed with EV71infection were included in this study, and20patients with febrile convulsion (FC) were chosen as control.2. CSF sample in acute phase from each patient was obtained by lumbar puncture right after admission if there were no contraindications. CSF samples were aliquoted and subjected to biochemical analyses (glucose, protein, and chloride), cytological analyses (cell count and white cell distribution), and microbiology test or frozen at-80℃for further cytokine determination.3. The concentrations of IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ in CSF were determined using the CBA Human Thl/Th2Cytokine Kit II following the manufacture’s specifications.4. All statistical analyses were performed using the SPSS software, version17.0. The nonparametric Mann-Whitney U test was used for data that did not show normal distribution, while data showed normal distribution were tested by Student’s t test. Differences between proportional data were analyzed using χ2or Fisher’s exact test as appropriate. Correlations between variables were calculated by Spearman’s rank correlation test (nonparametric data) or Pearson’s correlation test (normal data). Data were expressed as mean±SD. Ap value<0.05was considered statistically significant.Results:1. The duration of feverand duration of hospital stays were significantly higher in the ME group compared to the FC group. Examination of CSF revealed significantly higher white cell count (WBC) and protein levels in ME patients than those of FC cases. However, there was no significant difference between the two groups with respect to age, gender, and parameters of routine blood test.2. CSF IFN-y and IL-6concentrations were significantly higher in patients with ME than those with FC. However, CSF TNF-a, IL-10, IL-4and IL-2concentrations of ME group did not differ significantly from those of FC group.3. CSF IL-6level was significantly decreased in convalescent phase as compared to that in the acute phase, whereas no significant differences were observed between acute and convalescent phases for IFN-y, TNF-a, IL-10, IL-4and IL-2levels.4. CSF IL-6level correlated well with cytology parameters, whereas IFN-y and IL-10concentrations showed a poor correlation with cytology parameters in ME patients. In contrast, there was no correlation between CSF TNF-α, IL-4, or IL-2levels with cytology parameters in ME patients. Likewise, no association of these cytokines and cytology parameters was noted in FC patientsConclusions:1. IL-6and IFN-y might be associated with EV71-induced neuropathogenesis.2. CSF IL-6, IL-10and IFN-γ level correlated with cytology parameters.