[Gene expression profiling and verification for severe secondary pulmonary tuberculosis patients]

To explore the gene expression profiles of severe secondary pulmonary tuberculosis patients.

From May 2012 to October 2013, a total of 103 eligible patients with secondary pulmonary tuberculosis were recruited from Institution of Tuberculosis Research of PLA Hospital No. 309. They were divided into severe secondary pulmonary tuberculosis (severe group) (n = 57) and mild secondary pulmonary tuberculosis (mild group) (n = 46) by the severity of disease . At the same time age-matched healthy controls (n = 45) were selected from healthy subjects undergoing physical examination. Whole genome expression profiling was performed with Affymetrix Gene expression chips for 4 cases in severe group, 3 in mild group and 5 in healthy group. Cluster and bioinformatics analysies were performed on differentially expressed genes in severe versus mild group. The remainders of three groups were 53, 43 and 40 cases respectively used for verify the results of gene chip by real-time fluorescence quantitative PCR (RT-PCR). And 20 cases in severe group, 20 in mild group and 8 in control group were used to verify the expression level of jun oncogene (JUN) on behalf of differential expressed genes. Analysis of variance and non-parametric tests were used for statistic difference analysis among three groups.

There were 406 differentially expressed genes for severe and mild groups. There were 264 down-regulated gene and 142 up-regulated ones. The down-regulated genes were predominant. Cluster analysis show the similarity of gene expression profile in the same group . The result confirmed that the gene chip experiments were both repeatable and reliable. According to gene ontology, the differentially expressed genes were mainly involved in such biological processes as immune response, signal transduction, regulation of transcription (DNA-dependent), inflammatory response, antigen processing and presentation and chemotaxis, etc. Pathway analysis showed differentially expressed genes were involved in 22 pathways of immune response and inflammation. The major pathways included B cell receptor signaling, antigen processing and presentation, Toll-like receptor signaling, MAPK signaling and transforming growth factor-beta (TGF-β) signaling.Real-time fluorescence quantitative PCR (RT-PCR) analysis showed that the statistics of optical density for JUN was P < 0.001 in severe versus mild group. It was down-regulated in severe group. And the expression of JUN was conformed with the result of gene expression chip.

The patients of severe group have a larger number of differential expressed genes versus those of mild group. And severe lung tissue damage in severe group may be correlated with differences in gene expression.