GSE17423: Age-related para-inflammation in the neuroretina of the mouse.

To understand the age-related retinal gene changes, gene transcription profiles of neural retinal tissues from young adult (3-month) mice and old (20-month) mice were investigated by microarray. With age, 632 genes were up-regulated and 429 genes were down-regulated in the retina. Functional annotation showed that genes linked to immune responses and to tissue stress/injury responses were most modified by old age. Significant numbers of gene involved in the innate immune response including leukocyte activation, chemotaxis, endocytosis, complement activation, phagocytosis and myeloid cell differentiation were up-regulated and only a few were down-regulated. Increased microglial and complement activation in the aging retina was further confirmed by confocal microscopy of retinal tissues. The results suggest that retinal aging is accompanied with activation of a number of local inflammatory responses. A modified form of low-grade chronic inflammation (para-inflammation) characterizes these aging changes and involves mainly the innate immune system. Para-inflammation per se may be beneficial to normal retinal physiology in aging by promoting retinal homeostasis; conversely, dysreulation of the para-inflammation response may contribute to the pathogenesis of age-related retinal degeneration.

The Agilent Feature Extraction Software (FES) was used to read out and process the microarray image files. The raw data were normalized by dividing the intensity values by their median.