Dynamic Change Of Related Immune Factors In The Process Of MBL Against Mycoplasma Ovipneumoniae Infection

Sheep Mycoplasmal pneumonia(MP), is a serious one among animal affecting diseases. The outbreak of the epidemic in Xinjiang has been to bring a certain amount of losses to animal husbandry in recent years. Mannan-binding lectin(MBL), an anti-infective innate immune molecule which is synthesized and secreted into the blood by liver. Before antigen-antibody specific reaction, MBL could induce activation of the immune response as an important member of the innate immune system. The current studies have confirmed that MBL polymorphisms are correlated with a variety of diseases. Previous studies of our laboratory found that MBL gene was related with sheep MP resistant. In order to understand the relationship between the levels of MBL and mycoplasma infection in sheep and mechanism of MBL playing the immune effect, the mechanism of MBL anti-MP infection was researched in sheep through sheep individual level and at the cellular level in this study,experiments are as following:(1)From the individual level to study MBL anti-MP infection: sheep were selected into different groups according to serum MBL concentrations. After Mycoplasma Ovipneumoniae(MO) artificial infection, the changes of MBL and the expression of a variety of immune factors were detected and analyzed. The results showed that after artificial infection, serum MBL concentrations declined.With the extension of time of artificial infection, the immune levels change different. For sheep group with higher concentrations of MBL, its pro-inflammatory cytokines IL-2, IFN-γconcentration was relatively high, anti-inflammatory cytokine IL-4 after artificial infection was gradually increased after the day, then began to decline; for sheep group with low concentrations of MBL, TNF-α concentrations significantly increased,decreased with the soothing inflammation; complement C1 and C3 exhibited different changes after artificial infection. It proved that the complement pathway was activated after MP infection, which may be related to the concentration of MBL. MBL can increase sheep mycoplasma pneumoniae resistance.(2) Improve and identify of sheep tracheal epithelial cells in primary culture cells : sheep tracheal epithelial cells were extracted with type II collagen enzyme and wiping method to digest the tracheal mucosa.Cell morphology was observed, and cells were identified by immunohistochemical staining.(3) Research on MBL anti-MP infection from the cellular level : firstly, natural MBL were coarse extractied with PEG-6000 from sheep serum, then use Mannan-Aragarose affinity chromatography purified crude extract of MBL, resulting in relatively pure protein. Purified MBL protein were added to the original generation develop sheep tracheal mucosa epithelial cells before and after the inoculation of MO to observe the growth state of the cells and to detect changes of immune factors before and after infection. The studies found that the expressions of ICAM-1 gene and IL-6 gene of sheep tracheal epithelial cells after infection with Mycoplasma increased,the expression of MBL gene decreased. There was no significant difference comparedbetween groups. Apoptosis rates had also no significant difference between groups in the apoptosis experiments. But in the experiments of Mycoplasma affect sheep tracheal epithelial cells mortality found that cell survival rate of infection before joining the MBL protein group was significantly higher than infection after joining the MBL protein group. The effect of a certain concentration of MBL infected sheep tracheal epithelial cells fight infection MO was better than artificial MBL additional effect. The reason may be that MBL played a protective role before MO combined with sheep tracheal mucosa epithelial cells, preventing the combination of pathogenic bacteria and cells; MBL added after the the combination of the MO and sheep tracheal mucosal epithelial cell did not strong enough effect to block combination of the two.This study is based on th sheep individual level and cellular levels to reveal the role of the mannose-binding lectin in sheep anti-mycoplasma infection, to enrich the knowledge of mannose-binding lectin, provided an important basis for in-depth study of the pathogenesis of the MO and the effects and the application MBL immunological.