The Expression Of TLR7mRNA In The Lung And Brain Tissue Of Death Cases Infected By EV71

Objective: Hand foot and mouth disease(HFMD) caused a high morbidity and mortality in recent years, enterovirus 71(EV71) infection is prone to lead severe HFMD in infants and young children. But the exact pathogenesis is not yet entirely clear. Toll like receptor 7(TLR7) have been identified related with the recognition of some single-stranded RNA virus, but the study on relationship with EV71 on human tissue levels have not been reported so far. This subject is to detect the mRNA of TLR7 in FFPE of brain and lung tissue of EV71 infection by the method of Chromogenicin Situ Hybridization,trying to explore the significance of TLR7 in EV71 infection cases in the gene level.Methods:(1) Retrospectively analyze the hospitalized clinical data of HFMD death cases of pediatrics of our hospital from September of 2008,to February of 2015.(2)We Selected brain tissue and lung tissue samples of 9 cases which died of EV71 infection as experiment group(EV71 group)and 7 accidental deaths cases as control group which fixed by 10% neutral formalin, and paraffin-embedded. Observe and characterize pathological lung, brain tissue staining by HE.(3)In situ hybridization was used to detect the expression TLR7 mRNA in FFPE of lung and brain tissue. We graded the results according to the percentage of positive cells. Semi-quantitatively measured the positive integral optical density(IOD) values using image analysis software(IPP6.0), using SPSS18.0 statistical software to analyze the results.All patients of these death cases had signed an informed consent form and the subject had passed the audit of hospital ethics committee.Results:(1)Retrospective: there were 5145 cases diagnosed as HFMD in our hospital,874 patients admitted in from September of 2008 to February of 2015, including 464 severe cases, 77 critical cases,and 26 deaths cases.25 deaths cases were under the year of 3, and all deaths cases were accompanied by fever, leukocytosis and hyperglycemia, later period can occur shaking limbs, drowsiness and meningeal irritation.Coma, shock, hernia and neurogenic pulmonary edema, pulmonary hemorrhage would occur at last.3 of the 26 cases didn’t have hand and foot herpes or oral herpes and ulcers.15 cases had an X-ray diffuse or patchy shadow of exudation,which is the typical image of pulmonary edema, 9 cases of lung markings can be seen thickening, and 2 cases didn’t taking imaging and soon died. Rapid progress the disease were,and patients of deaths cases were died within 72 hours after admission.(2)Autopsy and pathology: the experimental group, nine cases of gross anatomy,the lung section were seen dark red liquid flow, gyrus widened sulcus shallow in brain.9 cases of deaths were seen infiltration of monocytes and lymphocytes of interstitial lung, part of pathological sections little red dye composition and inflammatory cell infiltration were visible alveolar; in biopsy of all cases, brain cells and brain interstitial showed edema, 5 cases of mesenchymal stem lesions sheet variability was visible.All patients had brain stem perivascular lymphocytic infiltration, 3cases showed obvious “vascular sets” phenomenon.(3)CIAH:TLR7mRNA positive signal expressed in monocytes-macrophages, lymphocytes, neutrophils and some bronchial and alveolar epithelial cell in the lung tissue. It expressed mainly in neurons, microglia, and part of the cytoplasm of lymphocytes in brain tissue.TLR7 expressed positive to strong positive in the lung tissue of EV71 group, IOD 253583.76, and in the control group the lung tissue expressed negative to weak positive,IOD 15627.29, P <0.05. In the brain,EV71 group showed a positive to strong positive signal, IOD 193728.00,it showed negative to slightly positive in the control group, IOD 20354.78, P <0.05. The difference was significant.Conclusions:(1)All deaths cases of HFMD had fever leukocytosis and hyperglycemia, later period can occur shaking limbs,drowsiness and meningeal irritation.Coma, shock, hernia and neurogenic pulmonary edema, pulmonary hemorrhage would occur at last.Some cases could not have hand and foot herpes or oral herpes and ulcers.And death case usually appear to infants under 3 years old.(2)The main cause of death of EV71 infection HFMD is meningitis, inflammation of the brain stem, cerebral edema, hernia formation, interstitial pneumonia in both lungs with pulmonary edema, congestion.(3)TLR7 distribute both in normal and infected lungs and brain tissue, it have a higher expression in the EV71 group than the control group. EV71 virus can stimulate an up-regulation of TLR7 expression.(4) TLR7 involved in the body’s immunity against the EV71 infection. As small single-strand RNA virus, EV71 can be recognised by TLR7, which may lead to the subsequent release of inflammatory cytokines.