(A) Schematic showing disc organ culture setup. Culturing discs under low pO2, in hyperosmolar, nutritionally limiting media with exposure to proinflammatory cytokines mimics the molecular changes characteristic of disc degeneration. (B) Microarray analysis of rat discs treated with TNF-α and IL-1β for 10 days. The heat map displays gene expression patterns of 1,036 genes after treatment. The relative levels of gene expression are depicted with a color scale, where blue represents the lowest and red represents the highest level of expression. (C) Volcano plot of microarray data depicting the significant differences (P < 0.05) in expression patterns between the control (Ctr.) and experimental (Exp.) groups, where the red plots represent a 1.5-fold or more difference in expression patterns between the two groups. (D) Pie chart showing differentially expressed genes based on major molecular and cellular functions. The total numbers of genes associated with each specific function are listed. Note that some genes may have multiple functions and can be classified in several categories (see Table 2), N = 4 independent experiments.
Markova et al. Arthritis Research & Therapy 2013 15:R121 doi:10.1186/ar4301