Mycoplasma Hyopneumoniae Destroyed the Inflammatory Balance of Respiratory Tract Through Suppressing the Function of SPLUNC1
[Background]Mycoplasma hyopneumoniae(Mhp)invades the body through respiratory mucosa,then it destroys the inflammatory balance and causes inflammatory damage.Short palate lung and nasal epithelial clone l(SPLUNC1)is a protein secreted by respiratory mucosa with important antibacterial and anti-inflammatory functions,it is considered to be a"signal sensor"for respiratory mucosa in the face of danger signals.[Objective]This study focused on the interaction between Mhp and SPLUNC1,and analyzed the influence of Mhp on the expression of SPLUNC 1 and the regulatory effect of SPLUNC 1 on the inflammatory response caused by Mhp.This study also revealed a new mechanism of inflammatory damage caused by Mhp,and it was of great significance to resolve the problem of persistent infection of Mhp.[Method]Quantitative PCR,indirect immunofluorescence and Western-blotting methods were used to detect the effects of Mhp on SPLUNC 1 transcription and expression in PBECs and piglets.Porcine SPLUNC 1 gene was cloned and amplified from the PBECs,and the eukaryotic and prokaryotic expression recombinant plasmids pCDNA3.1-SPLUNC1 and pET28a-SPLUNC 1 were constructed successfully.Meanwhile,siRNA interference sequence targeting SPLUNC 1 were also designed.The effect of SPLUNC 1 on the growth of Mhp was clarified by in vitro incubation experiment and SPLUNC 1 blocking experiment in mice.After over-expressing or siRNA interfering of SPLUNC 1,Western-blotting,IFA and ELISA were used to detect the effects of SPLUNC 1 on the Mhp adhesion,CXCL8 expression and the activation of MAPK pathway.[Result]Mhp infection induced inflammatory damage,accompanied by CXCL8,TNFα and IL-1β expression in the lung.Meanwhile,the transcription and protein expression of SPLUNC 1 was also inhibited in vivo and PBECs after Mhp infection.The above studies indicated that Mhp induced pulmonary inflammatory response and inhibited the expression of SPLUNC 1.Over-expression of SPLUNC 1 in PBECs significantly decreased CXCL8 expression,on the contrary,the knockdown of SPLUNC 1 by siRNA interference significantly increased CXCL8 expression.The result showed that SPLUNC 1 negatively regulated CXCL8 expression caused by Mhp infection.The growth of Mhp in vivo and vitro was not significantly inhibited by SPLUNC 1.Over-expression or siRNA interference of SPLUNC 1 also had no significant effect on the adhesion of Mhp.The over-expression of SPLUNC 1 inhibited the activation of pERK and IκBα,whereas siRNA interference of SPLUNC 1 upregulated the activation of pERK and IκBα.SPLUNC 1 inhibited CXCL8 expression by inhibiting the activation of MAPK-ERK pathway.[Conclusion]The respiratory mucosa regulated the expression of CXCL8 through SPLUNC 1 to maintain the inflammatory balance of the host.However,in the process of infection,Mhp destroyed the inflammatory balance by inhibiting SPLUNC 1 expression,thus causing inflammatory damage.Finally,this study provided an important basis for understanding the mechanism of infection and injury of Mhp.
Mycoplasma hyopneumoniaeinteraction between mycoplasma and hostinflammatory reactionSPLUNC1
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