Gene and Protein Expression Profiles in a Mouse Model of Collagen-Induced Arthritis

Abstract

The risk of rheumatoid arthritis (RA), an autoimmune disease, in the elderly population increases along with that of atherosclerosis, cardiovascular disease, type 2 diabetes, and Alzheimer's disease. Identifying specific biomarkers for RA can clarify the underlying molecular mechanisms and can aid diagnosis and patient care. To this end, the present study investigated the genes and proteins that are differentially expressed in RA using a mouse collagen-induced arthritis (CIA) model. We performed gene microarray and proteome array analyses using blood samples from the mice and found that 50 genes and 24 proteins were upregulated and 48 genes were downregulated by more than 2-fold in the CIA model relative to the control. The gene microarray and proteome array results were validated by evaluating the expression levels of select genes and proteins by real-time PCR and western blotting, respectively. We found that the level of integrin α2, which has not been previously reported as a biomarker of RA, was significantly increased in CIA mice as compared to controls. These findings provide a set of novel biomarkers that can be useful for diagnosing and evaluating the progression of RA.

Keywords: biomarker; collagen-induced arthritis; integrin α2.; microarray; proteome analysis.

Figure 1

Gross morphological and histological examination of CIA. (A) Gross observation of mouse paws. Shown are the fore paws (top) and hind paws (bottom) of control (n = 12) and CIA (n = 14) mice at 14 weeks of age. Scale bars = 10 mm. (B) H&E staining of sagittal sections of control and CIA mouse joints. Lower panels show enlarged views of the areas delineated by a box in the upper panels. Arrows indicate cartilage boundaries. Scale bars = 1 mm.

Figure 2

Validation of microarray and proteome array results by qRT-PCR. The expression of each gene shown in the figure was confirmed by qRT-PCR using specific primers. β-Actin served as an internal control. Data represent the mean ± SEM. *P < 0.05, **P < 0.01

Figure 3

Validation of microarray and proteome array results by western blotting. (A) Western blotting was performed using blood samples from control and CIA mice. GAPDH served as an internal control. (B) Relative fold change in band intensity of target proteins normalized to GAPDH level. Data represent the mean ± SEM. *P < 0.05