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Marinov L, Mangarov I, Nikolova I. Gender differences in collagen-induced arthritis (CIA) in mice. BIOTECHNOL BIOTEC EQ 2022. [DOI: 10.1080/13102818.2022.2027815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Lyubomir Marinov
- Department of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria
| | - Iliya Mangarov
- Department of Pediatrics, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
| | - Irina Nikolova
- Department of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria
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Abstract
The "Bermuda triangle" of genetics, environment and autoimmunity is involved in the pathogenesis of rheumatoid arthritis (RA). Various aspects of genetic contribution to the etiology, pathogenesis and outcome of RA are discussed in this review. The heritability of RA has been estimated to be about 60 %, while the contribution of HLA to heritability has been estimated to be 11-37 %. Apart from known shared epitope (SE) alleles, such as HLA-DRB1*01 and DRB1*04, other HLA alleles, such as HLA-DRB1*13 and DRB1*15 have been linked to RA susceptibility. A novel SE classification divides SE alleles into S1, S2, S3P and S3D groups, where primarily S2 and S3P groups have been associated with predisposition to seropositive RA. The most relevant non-HLA gene single nucleotide polymorphisms (SNPs) associated with RA include PTPN22, IL23R, TRAF1, CTLA4, IRF5, STAT4, CCR6, PADI4. Large genome-wide association studies (GWAS) have identified more than 30 loci involved in RA pathogenesis. HLA and some non-HLA genes may differentiate between anti-citrullinated protein antibody (ACPA) seropositive and seronegative RA. Genetic susceptibility has also been associated with environmental factors, primarily smoking. Some GWAS studies carried out in rodent models of arthritis have confirmed the role of human genes. For example, in the collagen-induced (CIA) and proteoglycan-induced arthritis (PgIA) models, two important loci - Pgia26/Cia5 and Pgia2/Cia2/Cia3, corresponding the human PTPN22/CD2 and TRAF1/C5 loci, respectively - have been identified. Finally, pharmacogenomics identified SNPs or multiple genetic signatures that may be associated with responses to traditional disease-modifying drugs and biologics.
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De Franco M, Peters LC, Correa MA, Galvan A, Canhamero T, Borrego A, Jensen JR, Gonçalves J, Cabrera WHK, Starobinas N, Ribeiro OG, Dragani T, Ibañez OM. Pristane-induced arthritis loci interact with the Slc11a1 gene to determine susceptibility in mice selected for high inflammation. PLoS One 2014; 9:e88302. [PMID: 24505471 PMCID: PMC3914970 DOI: 10.1371/journal.pone.0088302] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 01/06/2014] [Indexed: 02/05/2023] Open
Abstract
AIRmax (maximal inflammation) and AIRmin (minimal inflammation) mice show distinct susceptibilities to pristane-induced arthritis (PIA). The Slc11a1 gene, which regulates macrophage and neutrophil activity, is involved in this infirmity. AIRmaxSS mice homozygous for the non-functional Slc11a1 S (gly169asp) allele obtained by genotype-assisted crosses from AIRmax and AIRmin mice are more susceptible than mice homozygous for the Slc11a1 resistant (R) allele. The present work sought to identify the quantitative trait loci (QTL) regulating PIA and to examine the interactions of these QTL with Slc11a1 alleles in modulating PIA. Mice were given two ip injections of 0.5 mL pristane at 60 day intervals, and the incidence and severity of PIA was scored up to 160 days. Genome-wide linkage studies were performed to search for arthritis QTL in an F2 (AIRmax × AIRmin, n = 290) population. Significant arthritis QTL (LODscore>4) were detected on chromosomes 5 and 8, and suggestive QTL on chromosomes 7, 17 and 19. Global gene expression analyses performed on Affymetrix mouse 1.0 ST bioarrays (27k genes) using RNA from arthritic or control mice paws showed 419 differentially expressed genes between AIRmax and AIRmin mice and demonstrated significantly (P<0.001) over-represented genes related to inflammatory responses and chemotaxis. Up-regulation of the chemokine genes Cxcl1, Cxcl9, Cxcl5, Cxcl13 on chromosome 5 was higher in AIRmaxSS than in the other lines. Macrophage scavenger receptor 1 and hemeoxigenase (decycling) 1 genes on chromosome 8 were also expressed at higher levels in AIRmaxSS mice. Our results show that the gene expression profiles of the two arthritis QTL (on chromosomes 5 and 8) correlate with Slc11a1 alleles, resulting in enhanced AIRmaxSS mice susceptibility to PIA.
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Affiliation(s)
- Marcelo De Franco
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
- * E-mail:
| | | | - Mara A. Correa
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
| | - Antonella Galvan
- Department of Experimental Oncology, Istituto Nazionale dei Tumori, Milan, Italy
| | | | - Andrea Borrego
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
| | - José R. Jensen
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
| | | | | | - Nancy Starobinas
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
| | | | - Tommaso Dragani
- Department of Experimental Oncology, Istituto Nazionale dei Tumori, Milan, Italy
| | - Olga M. Ibañez
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
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Glant TT, Besenyei T, Kádár A, Kurkó J, Tryniszewska B, Gál J, Soós G, Szekanecz Z, Hoffmann G, Block JA, Katz RS, Mikecz K, Rauch TA. Differentially expressed epigenome modifiers, including aurora kinases A and B, in immune cells in rheumatoid arthritis in humans and mouse models. ACTA ACUST UNITED AC 2013; 65:1725-35. [PMID: 23653330 DOI: 10.1002/art.37986] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 04/16/2013] [Indexed: 12/24/2022]
Abstract
OBJECTIVE To identify epigenetic factors that are implicated in the pathogenesis of rheumatoid arthritis (RA), and to explore the therapeutic potential of the targeted inhibition of these factors. METHODS Polymerase chain reaction (PCR) arrays were used to investigate the expression profile of genes that encode key epigenetic regulator enzymes. Mononuclear cells from RA patients and mice were monitored for gene expression changes, in association with arthritis development in murine models of RA. Selected genes were further characterized by quantitative reverse transcription-PCR, Western blot, and flow cytometry methods. The targeted inhibition of the up-regulated enzymes was studied in arthritic mice. RESULTS A set of genes with arthritis-specific expression was identified by the PCR arrays. Aurora kinases A and B, both of which were highly expressed in arthritic mice and treatment-naive RA patients, were selected for detailed analysis. Elevated aurora kinase expression was accompanied by increased phosphorylation of histone H3, which promotes proliferation of T lymphocytes. Treatment with VX-680, a pan-aurora kinase inhibitor, promoted B cell apoptosis, provided significant protection against disease onset, and attenuated inflammatory reactions in arthritic mice. CONCLUSION Arthritis development is accompanied by changes in expression of a number of epigenome-modifying enzymes. Drug-induced down-regulation of the aurora kinases, among other targets, seems to be sufficient to treat experimental arthritis. Development of new therapeutics that target aurora kinases can potentially improve RA management.
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Stoop JN, Tibbitt CA, van Eden W, Robinson JH, Hilkens CMU. The choice of adjuvant determines the cytokine profile of T cells in proteoglycan-induced arthritis but does not influence disease severity. Immunology 2013; 138:68-75. [PMID: 23077978 DOI: 10.1111/imm.12019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 09/26/2012] [Accepted: 10/02/2012] [Indexed: 12/19/2022] Open
Abstract
Rheumatoid arthritis (RA) is a debilitating autoimmune disease characterized by chronic inflammation of the synovial joints. Collagen-induced arthritis (CIA) and proteoglycan-induced arthritis (PGIA) are mouse models of inflammatory arthritis; CIA is a T helper type 17 (Th17) -dependent disease that is induced with antigen in complete Freund's adjuvant, whereas PGIA is Th1-mediated and is induced using antigen in dimethyldioctadecyl-ammonium bromide (DDA) as an adjuvant. To investigate whether the type of adjuvant determines the cytokine profile of the pathogenic T cells, we have compared the effect of CFA and DDA on T-cell responses in a single arthritis model. No differences in incidence or disease severity between aggrecan-T-cell receptor transgenic mice immunized with aggrecan in either CFA or DDA were observed. Immunization with CFA resulted in a higher proportion of Th17 cells, whereas DDA induced more Th1 cells. However, the levels of interleukin-17 (IL-17) produced by T cells isolated from CFA-immunized mice after antigen-specific stimulation were not significantly different from those found in DDA-immunized mice, indicating that the increased proportion of Th17 cells did not result in significantly higher ex vivo IL-17 levels. Hence, the choice of adjuvant can affect the overall proportions of Th1 and Th17 cells, without necessarily affecting the level of cytokine production or disease incidence and severity.
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Affiliation(s)
- Jeroen N Stoop
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
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Non-MHC risk alleles in rheumatoid arthritis and in the syntenic chromosome regions of corresponding animal models. Clin Dev Immunol 2012; 2012:284751. [PMID: 23251214 PMCID: PMC3521484 DOI: 10.1155/2012/284751] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 08/13/2012] [Accepted: 09/30/2012] [Indexed: 11/29/2022]
Abstract
Rheumatoid arthritis (RA) is a polygenic autoimmune disease primarily affecting the synovial joints. Numerous animal models show similarities to RA in humans; some of them not only mimic the clinical phenotypes but also demonstrate the involvement of homologous genomic regions in RA. This paper compares corresponding non-MHC genomic regions identified in rodent and human genome-wide association studies (GWAS). To date, over 30 non-MHC RA-associated loci have been identified in humans, and over 100 arthritis-associated loci have been identified in rodent models of RA. The genomic regions associated with the disease are designated by the name(s) of the gene having the most frequent and consistent RA-associated SNPs or a function suggesting their involvement in inflammatory or autoimmune processes. Animal studies on rats and mice preferentially have used single sequence length polymorphism (SSLP) markers to identify disease-associated qualitative and quantitative trait loci (QTLs) in the genome of F2 hybrids of arthritis-susceptible and arthritis-resistant rodent strains. Mouse GWAS appear to be far ahead of rat studies, and significantly more mouse QTLs correspond to human RA risk alleles.
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Glant TT, Adarichev VA, Boldizsar F, Besenyei T, Laszlo A, Mikecz K, Rauch TA. Disease-promoting and -protective genomic loci on mouse chromosomes 3 and 19 control the incidence and severity of autoimmune arthritis. Genes Immun 2012; 13:336-45. [PMID: 22402741 DOI: 10.1038/gene.2012.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Proteoglycan (PG)-induced arthritis (PGIA) is a murine model of rheumatoid arthritis. Arthritis-prone BALB/c mice are 100% susceptible, whereas the major histocompatibility complex-matched DBA/2 strain is completely resistant to PGIA. To reduce the size of the disease-suppressive loci for sequencing and to find causative genes of arthritis, we created a set of BALB/c.DBA/2-congenic/subcongenic strains carrying DBA/2 genomic intervals overlapping the entire Pgia26 locus on chromosome 3 (chr3) and Pgia23/Pgia12 loci on chr19 in the arthritis-susceptible BALB/c background. Upon immunization of these subcongenic strains and their wild-type (BALB/c) littermates, we identified a major Pgia26a sublocus on chr3 that suppressed disease onset, incidence and severity via controlling the complex trait of T-cell responses. The region was reduced to 3 Mbp (11.8 Mbp with flanking regions) in size and contained gene(s) influencing the production of a number of proinflammatory cytokines. Additionally, two independent loci (Pgia26b and Pgia26c) suppressed the clinical scores of arthritis. The Pgia23 locus (∼3 Mbp in size) on chr19 reduced arthritis susceptibility and onset, and the Pgia12 locus (6 Mbp) associated with low arthritis severity. Thus, we have reached the critical sizes of arthritis-associated genomic loci on mouse chr3 and chr19, which are ready for high-throughput sequencing of genomic DNA.
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Affiliation(s)
- T T Glant
- Department of Orthopedic Surgery, Section of Molecular Medicine, Rush University Medical Center, Chicago, IL 60612, USA.
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Ahlqvist E, Ekman D, Lindvall T, Popovic M, Förster M, Hultqvist M, Klaczkowska D, Teneva I, Johannesson M, Flint J, Valdar W, Nandakumar KS, Holmdahl R. High-resolution mapping of a complex disease, a model for rheumatoid arthritis, using heterogeneous stock mice. Hum Mol Genet 2011; 20:3031-41. [PMID: 21565963 DOI: 10.1093/hmg/ddr206] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Resolving the genetic basis of complex diseases like rheumatoid arthritis will require knowledge of the corresponding diseases in experimental animals to enable translational functional studies. Mapping of quantitative trait loci in mouse models of arthritis, such as collagen-induced arthritis (CIA), using F(2) crosses has been successful, but can resolve loci only to large chromosomal regions. Using an inbred-outbred cross design, we identified and fine-mapped CIA loci on a genome-wide scale. Heterogeneous stock mice were first intercrossed with an inbred strain, B10.Q, to introduce an arthritis permitting MHCII haplotype. Homozygous H2(q) mice were then selected to set up an F(3) generation with fixed major histocompatibility complex that was used for arthritis experiments. We identified 26 loci, 18 of which are novel, controlling arthritis traits such as incidence of disease, severity and time of onset and fine-mapped a number of previously mapped loci.
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Affiliation(s)
- Emma Ahlqvist
- Division of Medical Inflammation Research, Department of Medical Biochemistry, Biophysics Karolinska Institute, 17177 Stockholm, Sweden
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Identifying a major locus that regulates spontaneous arthritis in IL-1ra-deficient mice and analysis of potential candidates. Genet Res (Camb) 2011; 93:95-103. [PMID: 21414240 DOI: 10.1017/s0016672310000704] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify genetic loci that regulate spontaneous arthritis in interleukin-1 receptor antagonist (IL-1ra)-deficient mice, an F2 population was created from a cross between Balb/c IL-1ra-deficient mice and DBA/1 IL-1ra-deficient mice. Spontaneous arthritis in the F2 population was examined and recorded. Genotypes of those F2 mice were determined using microsatellite markers. Quantitative trail locus (QTL) analysis was conducted with R/qtlbim. Functions of genes within QTL chromosomal regions were evaluated using a bioinformatics tool, PGMapper, and microarray analysis. Potential candidate genes were further evaluated using GeneNetwork. A total of 137 microsatellite markers with an average of 12 cM spacing along the whole genome were used for determining the correlation of arthritis phenotypes with genotypes of 191 F2 progenies. By whole-genome mapping, we obtained QTLs on chromosomes 1 and 6 that were above the significance threshold for strong Bayesian evidence. The QTL on chromosome 1 had a peak near D1Mit55 and D1Mit425 at 82·6 cM. It may account for as much as 12% of the phenotypic variation in susceptibility to spontaneous arthritis. The QTL region contained 208 known transcripts. According to their functions, Mr1, Pla2g4a and Fasl are outstanding candidate genes. From microarray analysis, 11 genes were selected as favourable candidates based on their function and expression profiles. Three of those 11 genes, Prg4, Ptgs2 and Mr1, correlated with the IL-1ra pathway. Those genes were considered to be the best candidates.
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Peters LC, Jensen JR, Borrego A, Cabrera WHK, Baker N, Starobinas N, Ribeiro OG, Ibañez OM, De Franco M. Slc11a1 (formerly NRAMP1) gene modulates both acute inflammatory reactions and pristane-induced arthritis in mice. Genes Immun 2006; 8:51-6. [PMID: 17122779 DOI: 10.1038/sj.gene.6364358] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mice selected for the maximum acute inflammatory reaction (AIRmax) are highly susceptible to pristane-induced arthritis (PIA), whereas mice selected for the minimum response (AIRmin) are resistant. These lines show distinct patterns of leukocyte infiltration and R and S allele frequency disequilibrium of the solute carrier family 11a member 1 (Slc11a1) gene. In order to study the interactions of the Slc11a1 R and S alleles with the inflammation modulating Quantitative Trait Loci (QTL) during PIA development, homozygous AIRmax(RR), AIRmax(SS), AIRmin(RR) and AIRmin(SS) lines were produced by genotype-assisted breedings. These mice received two intraperitoneal injections of 0.5 ml pristane at 60-day intervals, and the subsequent development of arthritis was assessed for 210 days. Cytokine-secreting cell profiles were investigated using enzyme-linked immunospot. Arthritis incidence in AIRmax(RR) mice reached 29%, whereas PIA incidence in AIRmax(SS) mice was 70% by day 180. AIRmin(RR) mice were resistant, whereas 13.3% of AIRmin(SS) mice became arthritic. The presence of the defective S allele also increased arthritis severity, although acute inflammation was higher in mice bearing the R allele. A predominant Th0/Th2-type response in Slc11a1(SS) mice was observed. These results indicate that Slc11a1 is a strong candidate for the QTL modulating acute inflammation and for PIA.
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Affiliation(s)
- L C Peters
- Laboratório de Imunogenética, Instituto Butantan, São Paulo, Brazil
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Murad YM, Szabó Z, Ludányi K, Glant TT. Molecular manipulation with the arthritogenic epitopes of the G1 domain of human cartilage proteoglycan aggrecan. Clin Exp Immunol 2005; 142:303-11. [PMID: 16232217 PMCID: PMC1809506 DOI: 10.1111/j.1365-2249.2005.02921.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Systemic immunization of BALB/c mice with human cartilage proteoglycan (PG) aggrecan induces progressive polyarthritis. The G1 domain of the PG aggrecan molecule contains most of the T cell epitopes, including three immunodominant ('arthritogenic') and at least six subdominant T cell epitopes. The three dominant T cell epitopes (P49, P70 and P155) were deleted individually or in combination by site directed mutagenesis, and the recombinant human G1 (rhG1) domain (wild type and mutated) proteins were used for immunization. Close to 100% of BALB/c mice immunized with the wild-type (nonmutated) rhG1 domain developed severe arthritis, which was 75% in the absence of P70 (5/4E8) epitope, and very low (< 10% incidence) when all three dominant T cell epitopes were deleted. The onset was delayed and the severity of arthritis reduced in animals when dominant T cell epitopes were missing from the immunizing rhG1 domain. The lack of T cell response to the deleted epitope(s) was specific, but the overall immune response against the wild-type rhG1 domain of human PG was not significantly affected. This study helped us to understand the dynamics and immune-regulatory mechanisms of arthritis, and supported the hypothesis that the development of autoimmune arthritis requires a concerted T cell response to multiple epitopes, rather than the immune response to a single arthritogenic structure.
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Affiliation(s)
- Y M Murad
- Section of Molecular Medicine, Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA
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Nandakumar KS, Holmdahl R. A genetic contamination in MHC-congenic mouse strains reveals a locus on chromosome 10 that determines autoimmunity and arthritis susceptibility. Eur J Immunol 2005; 35:1275-82. [PMID: 15761851 DOI: 10.1002/eji.200425925] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Among the arthritis-susceptible MHC (H-2)-congenic mouse strains, B10.RIII mice are highly susceptible to collagen-induced arthritis. Surprisingly, the B10.RIII strain was also more susceptible to the T cell independent model CAIA (collagen-antibody-induced arthritis). Through genome-wide genotyping, we found that the B10.RIII and B10.Q strains differed not only in chromosome 17 (MHC) but also in a region on chromosome 10, which contained a fragment from the MHC donor RIIIS/J. We isolated the chromosome 10 as well as the chromosome 17 segments on the B10.RIII and B10.Q backgrounds. Congenic mice containing the RIIIS/J-derived chromosome 10 segment showed significantly higher susceptibility and severity of arthritis with an enhanced autoimmune response to type II collagen. Furthermore, this chromosomal segment significantly promoted CAIA. Similarly, the RIIIS/J segment in chromosome 17 also promoted CAIA independently of other gene segments. These data show that other gene regions, apart from MHC class II, may explain effects both at the priming and effector level of arthritis observed in widely used MHC congenic strains. These new congenic fragments, on both chromosome 10 and 17, provide new mouse strains suitable for studies aiming at positional cloning of new genes associated with arthritis.
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Szabó Z, Szántó S, Végvári A, Szekanecz Z, Mikecz K, Glant TT. Genetic control of experimental spondylarthropathy. ACTA ACUST UNITED AC 2005; 52:2452-60. [PMID: 16059927 DOI: 10.1002/art.21193] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE To characterize experimentally induced spondylarthropathy (SpA) in arthritis-susceptible inbred mice and in their F(1) and F(2) hybrid generations of susceptible and resistant mouse strains. METHODS SpA was induced in susceptible BALB/c and C3H/HeJCr (C3H) strains of mice, and in their F(1) and F(2) generations derived from intercrosses with arthritis- and/or spondylitis-resistant DBA/2 and DBA/1 parent strains, by systemic immunization with cartilage proteoglycan (PG) aggrecan. The incidence and severity of PG-induced spondylitis (PGIS) were scored histologically, and these scores for spine involvement were correlated with serum antibody and cytokine levels and with in vitro T cell responses to cartilage PG. RESULTS PGIS was induced by systemic immunization with cartilage PG in adjuvant, and approximately 60-70% of susceptible mouse strains and their F(2) hybrids developed spondylitis either with or without arthritis. Adjuvants, particularly those activating the innate immune system and enforcing the Th1 dominance, had significant effects on the outcome and progression of SpA. The DBA/1 strain appeared to carry genes protecting this strain and its F(1) and F(2) hybrids from spondylitis, whereas the DBA/2 strain, although resistant to PGIS, harbored genes permitting PGIS in its hybrid generations. Arthritis- and/or spondylitis-susceptible BALB/c and C3H parent strains and their F(2) hybrids exhibited the highest incidence and severity of spondylitis. CONCLUSION PGIS, a murine model of autoimmune spondylitis, shows similarities to ankylosing spondylitis. Segregation of susceptibility to PG-induced arthritis (PGIA) from that to PGIS in different genetic crosses suggests that PGIA and PGIS are separate diseases. Therefore, this model allows for the elucidation of genetic components involved in the etiology of SpA, independent of those controlling the susceptibility to PGIA.
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