The Role Of IP-10 To Pulmonary Pathogenic Effect Induced By Influenza Virus

ObjectiveInfluenza Virus,which belongs to the Orthomyxovirus,can be divided into three types.Pandemic was often caused by the A-type.The most famous world-wide influenza pandemic occurred in 1918-1919,causing 50 percent infection of the world's population and 20 million's deaths.Avian influenza virus belongs to the influenza A virus.In the past,it was considered that human can't be infected by the avian influenza virus.This theory has been corrected by the incident that someone was infected by H5N1 avian influenza virus in 1997 with relatively high mortality.Later, cases of human infected by H9N2 and H7N7 avian influenza virus occcured.So far,humans infected by avian influenza virus were almost killed by respiratory distress,which was caused by viral pneumonia.It is reported that pulmonary pathology of these patients are increasing inflammatory cells,substantial necrosis and interstitial fibrosis of lung.These pathological changes may be related to actions of certain cytokines.Interferon-inducible protein 10,which belongs to CXC chemokine,is a kind of 10KD polypeptide.It is induced by IFN-r and secreted by several kinds of T cells,macrophages,Endothelial cells and astrocytes.IP-10,which connect with its receptor(CXCR3),can activate T cells,NK cells and monocytes in blood,and play a great role in different inflammation.Monocytes or macrophages,which infected by Influenza A virus,can secrete IP-10.However,the relationship between the chemokine level and lung lesions of influenza virus pneumonia is still unknown.But it has been confirmed through experiments,when infected with klebsiella,the level of IP-10 are closely related with the severity of lung disease of infected animals.This experiment is the study of the role of IP-10 to pulmonary pathogenic effect induced by influenza virus in the lungs of mice,which were firstly given a certain amou nt of recombinant mouse cytokines IP-10 following infection with influenza virus,and comparing the changes with the mice only infected with influenza virus.Methods25 mice were randomly divided into three groups,5 mice as normal control group, 10 mice as infection control group and 10 mice as IP-10 injected group.IP-10 injected group mice were injected with a certain amount of recombinant mouse IP-10,then these mice were infected with influenza virus.Control group of mice infected with the same dose of influenza virus while there weren't any treatment on normal control group of mice.All mice of three groups were executed 5 days after the infection.Calculate the lung index of these mice.Make paraffin biopsy,carry out H.E staining,observe the pathological changes under microscope and carry out patholigical scores in interstitial pneumonia.ResultsLung indexIn IP-10 injected group,lung index is higher than the infected control group.The lung injury of IP-10 injection group is much severe than the simply infected group.Pathological change of LungIP-10 injected group and infection control group mice showed lung pathological changes of interstitial pneumonia.However,there are much severe pulmonary pathological changes in IP-10 injected mice,including alveolar edema fluid of cavity,which leads the formation of hyaline membrane and inflammatory cells infiltion mainly caused by lymphocytes on columnar epithelium of alveolar bronchiole wall.The results of interstitial pneumonia scoresAfter careful treatment of scores of the mice,T test has been carried out on the two groups.It proves that there is significant interstitial pneumonia pathological scoring difference.The IP-10 injected group of mice shows more obvious changes.DiscussionThe cases that infected with avian influenza virus has become a health problem concemed about all over the world.This is not only because the high mortality rate among patients,but the existence of large-scale popular risk factors and lacking of effective treatment.Patients infected with avian influenza virus mainly die of respiratory failure caused by viral pneumonia.Thus control of lung inflammatory response would significantly reduce the mortality in patients with avian fluenza.This experiment focuses on chemokine IP-10 that induces inflammatory cells into lung tissue and studies the relationship between IP-10 level and the pathological changes on a pneumonia induced by influenza virus.These results suggest that IP-10 factor,has great impact on the degree of lung inflammation.Control of IP-10 level would effective on the treatment of inflammatory response of lung caused by influenza virus infection.ConclusionIP-10 levels is closely related to the severity of pneumonia,which is a common complication of influenza virus infection.