Microarray analysis identifies distinct subpopulations of arthritic mice deficient for interleukin 1 receptor antagonist

Rheumatoid arthritis (RA) is a heterogeneous disease with clinical and biological polymorphisms. However, little is known about baseline molecular variations among individual RA patients. The purpose of this study was to address this issue using F2 intercross mice generated from arthritis-prone BALB/c and arthritis-resistant DBA/1 mice deficient for interleukin 1 receptor antagonist (Il1rn). Two distinct subpopulations of arthritic mice were identified in the 38 mice studied. One subgroup of diseased mice was characterized by myeloid cell dominant inflammation, whereas the other was mainly associated with increased anti-apoptotic activities of inflammatory cells. Keywords: disease state analysis Thirteen F2 mice, 18 with arthritis and 18 without, were included in this study. Total RNAs were extracted from individual spleens for Affymmetrix mouse genome array analysis. Normalized data were hierarchically clustered to identify subpopulations of arthritic mice.