Objective

2

To explore the molecular mechanism of "transmission between the lung and brain" of influenza based on Janus kinase 1/signal transducer and activator of transcription 1（JAK1/STAT1） signaling pathway and further investigate the intervention effect of Maxing Shigantang （MXSGT）.

Method

2

A total of 100 SPF BALB/c mice were randomly divided into a normal group，a model group，an oseltamivir group （21.63 mg·kg

-1

·d

-1

），an antiviral granules group（3.9 g·kg

-1

·d

-1

）， and an MXSGT group（6.05 g·kg

-1

·d

-1

）， with 20 mice in each group. The pneumonia model was induced in mice except for those in the normal group by intranasal infection of influenza A virus（IAV）. Twenty-four hours after modeling，mice were treated with corresponding drugs， while those in the normal group and the model group received the same amount of normal saline by gavage， once a day for 3 and 7 days. The pathological changes in the lung and brain were observed by hematoxylin-eosin（HE）staining. The mRNA expression of IAV nucleoprotein（NP），JAK1， and STAT1 in the lung and brain was detected by real-time quantitative polymerase chain reaction（Real-time PCR）， and the protein expression of JAK1 and STAT1 in the lung and brain was detected by Western blot. Immunohistochemical method was used to detect the expression of phosphorylated（p）-STAT1 in the lung and brain tissues， and enzyme-linked immunosorbent assay（ELISA） was used to detect the serum levels of interleukin-1

β

（IL-1

β

） and interleukin-10（IL-10）.

Result

2

Compared with the normal group， the model group showed obvious pathological changes in the lung tissues and cerebral cortex， increased relative mRNA expression of IAV NP in the lung （

P

<

0.01）， elevated mRNA and protein expression of JAK1 and STAT1 in the lung and brain tissues （

P

<

0.05，

P

<

0.01），up-regulated expression level of p-STAT1 in lung tissues and cerebral cortex （

P

<

0.05，

P

<

0.01）， and increased serum level of IL-1

β

（

P

<

0.05）. Compared with the model group， the MXSGT group showed alleviated pathological damage to lung tissues and cerebral cortex， decreased relative mRNA expression of IAV NP in lung tissues（

P

<

0.01），reduced mRNA and protein expression levels of JAK1 and STAT1 in lung tissues and brain tissues（

P

<

0.05，

P

<

0.01）， and increased serum level of IL-10（

P

<

0.01）.

Conclusion

2

The abnormal activation of the JAK1-STAT1 signaling pathway may be one of the molecular mechanisms of "transmission between the lung and brain" of influenza. As an effective compound prescription against the influenza virus，MXSGT can alleviate the pathological damage of brain tissues in mice infected with IAV by regulating the level of cytokines mediated by this pathway.