Identification of new quantitative trait loci in mice with collagen‐induced arthritis

Abstract

Objective. Collagen-induced arthritis (CIA) in the mouse is one of the most widely used autoimmune experimental models, with many features similar to rheumatoid arthritis. This study sought to identify potential genetic regulatory mechanisms of CIA in major histocompatibility complex-matched (H2-q) F 2 hybrid mice.Methods. We used 126 polymorphic markers to perform simple sequence-length polymorphism analysis on 290 F 2 hybrids of arthritis-susceptible (DBA/1J) and arthritis-resistant (FVB/N) inbred mouse strains. The major clinical traits (disease severity and onset) were assessed, and serum antibodies specific to type II collagen (CII) were determined by enzyme-linked immunosorbent assay in 270 F 2 mice. Lymph nodes from 94 F 2 mice were used to test the ratio of CD4 to CD8 by fluorescence-activated cell sorter analysis, and cell proliferation was determined by XTT test.Results. Two quantitative trait loci (QTLs) identified in previous studies were confirmed; these were severity-controlling Cia2 and onset-controlling Cia4 on chromosome 2. Moreover, we identified 5 new QTLs, 1 for CII-specific IgG2a antibodies on chromosome 5, 2 controlling the CII-specific IgG1 antibody response on chromosomes 10 and 13, 1 for the CD4:CD8 ratio on chromosome 2, and 1 for cell proliferation (measured by XTT test) on chromosome 16. Complement component C5 was identified as the probable main candidate gene for the QTLs Cia2 and Cia4. F 2 mice carrying a 2-basepair deletion of C5, the FVB/N allele, had low incidence and less severe disease as compared with those carrying the DBA/1J allele.Conclusion. This genome scan provides additional evidence confirming the role of C5 as a probable candidate gene for Cia2 and Cia4 loci, and identifies new QTLs controlling new traits in autoimmune arthritis.

Using an advanced intercross line to identify quantitative trait loci controlling immune response during collagen-induced arthritis

“…However, it was successfully used to refine three QTLs previously identified in the F2 progeny, indicating that this AIL could be used for QTL high-resolution mapping. 11,12 Then, we examined the heterogeneity and recombination frequencies, which are important parameters for QTL mapping accuracy. Heterogeneity was tested to investigate the allele distribution on four chromosomes and it was estimated from the percentage of DBA/1 allele of the markers used for genotyping.…”

“…The methods of measuring both antibodies and T-cell subsets were described in detail earlier. 11 To determine the ROS production, we used a modified version of a previously described oxidative burst activity flow cytometry assay. 27 Briefly, 50 ml blood from 172 (DBA/1 Â FVB/N) F 12 AIL mice were lysed with 1000 ml erythrocyte lysis buffer for 10 min at room temperature and cells were resuspended in RPMI 1640 medium without fetal calf serum.…”

“…Primers for informative markers were ordered from Metabion GmbH (PlaneggMartinsried, Germany). Genotyping of 308 AIL mice was performed on DNA extracted from tail tips by using PCR amplification as described earlier 11 or by a PCR-restriction fragment length polymorphism method.…”

“…11,12 In this study, in order to test the possibility of identifying QTLs directly in AIL, we genotyped 308 F11/12 AIL mice with 109 genetic markers covering four chromosomes, with an average intermarker distance of 5.5 Mb. Several normally distributed immune-response quantitative traits, such as antibodies to collagen type II and T-cell subset proportions in lymph nodes as well as reactive oxygen species (ROS) were investigated.…”

Dissection of the genetic complexity of arthritis using animal models

“…At least 25 loci are of importance in crosses that involve the C57/Black10 gene background with a number of other mouse backgrounds, but which share the MHC [H2q] gene region [25,26,40,41]. The pattern and penetrance of such loci between the different crosses varies, indicating the complexity of different pathways in CIA.…”