Screening for genes associated with natural killer cell mediated cytotoxicity in pneumonia mice infected with influenza virus and regulation of two herbal anti-virus formulas

Abstract

To investigate the regulation of two herbal anti-virus formulas on gene expression profile associated with natural killer cell (NK cell) mediated cytotoxicity in pneumonia mice infected with influenza virus. According to random number table, 90 ICR mice were divided into nine groups with 10 mice in each group: normal group (N), model group (M), oseltamivir group (control group, C), low-dose, medium-dose and high-dose Shufeng Xuanfei formula groups (SL, SM, SH groups), and low-dose, medium-dose and high-dose Jiebiao Qingli formula groups (JL, JM, JH groups). The model of pneumonia was reproduced by nasal dropping influenza virus A (FM1) in mice. N group was given isotonic saline 0.05 ml in nasal drops. After 2 hours of model-building, C group was received 11.375 mg×kg⁻¹×d⁻¹ oseltamivir phosphate. Shufeng Xuanfei formula (mainly honeysuckle, forsythia and radix isatidis, etc.) with 3.76, 1.88 and 0.94 g×kg⁻¹×d were administrated to SH, SM and SL groups by gastric irrigation respectively. Jiebiao Qingli formula (mainly ephedra, gypsum, glycyrrhiza glabra, etc.) with 4.36, 2.18 and 1.09 g×kg⁻¹×d⁻¹ were administrated to JH, JM and JL groups by gastric irrigation respectively. In N and M groups, normal saline was administrated with gastric perfusion. Each group was in equal dose of 0.2 ml daily over a 4-day period. Total RNA in lung tissue of mice were extracted in each group, then gene chips were used to screen these RNA samples. Some genes involved NK cell mediated cytotoxicity were selected, with "I" representing of signal intensity. These candidate genes were verified by real-time fluorescent quantitation polymerase chain reaction (PCR) and Western blotting. In the pathway of NK cell mediated cytotoxicity, M group up-regulated 43 genes expression, and 36, 29, 22, 21, 20 and 10 genes showed down-regulation in SM, JM, SL, JH, SH and JL groups, respectively. Apart from gene co-expression network in SH, SL, JH, JM and JL, SM also expressed other differential genes which SH, SL, JH, JM and JL did not. So medium-does Shufeng Xuanfei formula had the most significant regulation in gene expression of NK cell mediated cytotoxicity. By real-time PCR and Western blotting experiments showed that compared with the M group, mRNA and protein expression of tumor necrosis factor-α (TNF-α) in these two formula groups were significantly down-regulated, especially prominent in SM group and JM group (TNF-α mRNA: 1.07 ± 0.19, 1.19 ± 0.14 vs. 3.20 ± 0.56, both P<0.01). Influenza viral replication in host cell, which means influenza antigens exposure in infected cells as target cells. NK cells recognize and exert cell mediated cytotoxic function against influenza antigens. Genes associated with NK cell mediated cytotoxicity in influenza infection were up-regulated. Shufeng Xuanfei and Jiebiao Qingli formulas could down-regulate these genes. The mechanism of down-regulated genes is that the number of influenza infected cells and NK cells activation decreases in treatment with two formulas.