Peter Kjellén

Genetic control of collagen‐induced arthritis in a cross with NOD and C57BL/10 mice is dependent on gene regions encoding complement factor 5 and FcγRIIb and is not associated with loci controlling diabetes

The nonobese diabetic (NOD) mouse spontaneously develops autoimmune‐mediated diseases such as diabetes and Sjögren′s syndrome. To investigate whether NOD genes also promote autoimmune‐mediatedarthritis we established a NOD strain with an MHC class II fragment containing the Aq class II gene predisposing for collagen induced arthritis (NOD.Q). However, this mouse was resistant to arthritis in contrast to other Aq expressing strains such as B10.Q and DBA/1. To determine the major resistance factor/s, a genetic analysis was performed. (NOD.Q×B10.Q)F1 mice were resistant, whereas 27% of the (NOD.Q×B10.Q)F2 mice developed severe arthritis. Genetic mapping of 353 F2 mice revealed two loci associated with arthritis. One locus was found on chromosome 2 (LOD score 9.8), at the location of the complement factor 5 (C5) gene. The susceptibility allele was from B10.Q, which contains a productive C5 encoding gene in contrast to NOD.Q. The other significant locus was found on chromosome 1 (LOD score 5.6) close to the Fc‐gamma receptor IIb gene, where NOD carried the susceptible allele. An interaction between the two loci was observed, indicating that they operate on the same or on interacting pathways. The genetic control of arthritis is unique in comparison to diabetes, since none of these loci have been identified in analysis of diabetes susceptibility.

The structural basis of MHC control of collagen-induced arthritis; binding of the immunodominant type II collagen 256 – 270 glycopeptide to H-2Aq and H-2Ap molecules

The Aq major histocompatibility complex (MHC) class II molecule is associated with susceptibility to murine collagen‐induced arthritis (CIA), whereas the closely related H‐2Ap molecule is not. To understand the molecular basis for this difference, we have analyzed the ability of H‐2Aq and H‐2Ap molecules (referred to as Aq and Ap) to bind and present collagen type II (CII)‐derived glycosylated and non‐glycosylated peptides. T cell clones specific for the immunodominant CII 256 – 270 peptide and restricted to both Aq and Ap molecules were identified. When these clones were incubated with CII protein and either Aq‐ or Ap‐expressing antigen‐presenting cells (APC), only Aq‐expressing APC were able to induce stimulation. With the use of Aβ transgenic mice this could be shown to be solely dependent on the MHC class II molecule itself and to be independent of other MHC‐ or non‐MHC genes. Peptide binding studies were performed using affinity‐purified MHC class II molecules. The CII 256 – 270 peptide bound with lower affinity to the Ap molecule than to the Aq molecule. Using a set of alanine‐substituted CII 256 – 270 peptides, MHC class II and T cell receptor (TCR) contacts were identified. Mainly the side chains of isoleucine 260 and phenylalanine 263 were used for binding both the Aq and Ap molecule, i.  e. the peptide was orientated similarly in the binding clefts. The major TCR contact amino acids were lysine 264, which can be posttranslotionally modified, and glutamic acid 266, which is the only amino acid in the heterologous peptide which differs from the mouse sequence. Glycosylation at positions 264 and 270 of the CII 256 – 270 peptide did not change the anchor positions used for binding to the Aq or Ap molecules. The autologous form of the peptide (with aspartic acid at position 266) bound with lower affinity to the Aq molecule as compared with the heterologous peptide. The variable affinity displayed by the immunodominant CII 256 – 270 peptide for different MHC class II molecules, the identification of MHC and TCR contacts and the significance of glycosylation of these have important implications for the understanding of the molecular basis for inherited MHC class II‐associated susceptibility to CIA and in turn, for development of novel treatment strategies in this disease.

Screening of several H-2 congenic mouse strains identified H-2q mice as highly susceptible to MOG-induced EAE with minimal adjuvant requirement

We identified H-2(q) as a susceptible genotype for MOG-induced EAE by systematic screening of a series of H-2 congenic B10 mouse strains. A series of H-2(q)-bearing strains with divergent gene backgrounds were subsequently investigated. DBA/1 mice were highly susceptible to MOG(1-125)- and MOG(79-96)-induced EAE in the absence of pertussis toxin. Immunisation with MOG(1-125) and MOG(79-96) induced an autoreactive T-cell response in DBA/1 mice. Brain histopathology revealed T-cell and macrophage-infiltrated lesions with associated demyelination. The important features which make this an appropriate model of human disease are high sensitivity to MOG and dependence of an immunodominant peptide region homologous to that implicated in multiple sclerosis.

Influence on Spontaneous Tissue Inflammation by the Major Histocompatibility Complex Region in the Nonobese Diabetic Mouse

We investigated the role of the major histocompatibility complex (MHC) region in the specificity of autoimmunity by analysing specifically the development of sialadenitis, but also insulitis, nephritis and autoantibody production in autoimmune‐prone nonobese diabetic (NOD) mice where the MHC H2g7 haplotype had been exchanged for the H2q (NOD.Q) or H2p (NOD.P) haplotype. The exchange of H2 haplotype did not affect the frequency of sialadenitis because the H2q and H2p congenic NOD strains developed sialadenitis with the same incidence as NOD. However, the severity of sialadenitis varied among the strains, as NOD.Q > NOD > NOD.P. At 11–13 weeks of age, the NOD.Q (H2q) female mice developed more severe sialadenitis compared to NOD.P (H2p) (P = 0.038). At 20 weeks, the NOD (H2g7) female mice showed more severe sialadenitis than NOD.P (P = 0.049). This is in contrast to the development of insulitis in the present strains, because the incidence of insulitis was almost completely inhibited by the replacement of the H2g7 haplotype of NOD. The incidence of insulitis in NOD.Q was 11–22%, compared to 75% in NOD, which correlated well with lower titres of anti‐glutamic acid decarboxylase (anti‐GAD) antibodies in NOD.Q compared to NOD (P = 0.009). However, the introduction of the H2q haplotype into the NOD strain instead directed the autoimmune response towards the production of lupus types of autoantibodies, because the incidence of antinuclear antibodies (ANA) in NOD.Q was 89% compared with 11% in NOD.P and 12% in NOD mice, which in turn correlated with a high incidence of nephritis in NOD.Q compared to NOD. Consequently, we show that different haplotypes of MHC are instrumental in directing the specificity of the spontaneous autoimmune inflammation.

The H2-Ab gene influences the severity of experimental allergic encephalomyelitis induced by proteolipoprotein peptide 103-116

Immunization of H2(p) and H2(q) congenic C3H mouse strains with the PLP 103-116 peptide elicited two distinct experimental allergic encephalomyelitis (EAE) disease courses. C3H.Q (H2(q)) mice developed an acute-phase disease with classical ascending paralytic signs whereas C3H.NB (H2(p)) developed a highly variable disease course with symptoms originating from CNS above the spinal chord. C3H.Q lacks functional H2-E molecules and share H2-Aalpha with C3H.NB. To examine if the differences found at positions 85, 86, 88, and 89 in the Abeta-chains account for disease susceptibility, H2(q) mice were made transgenic with the Ab(p) gene. The Ab(p)-transgenic mice on the C3H.Q background developed a more severe disease course, demonstrating the importance of class II. However, the onset was not affected and the disease showed a classical ascending paralysis similar to the C3H.Q suggesting that the observed brain symptoms were related to nonclass II genes. Inhibition studies performed on affinity purified MHC class II molecules indicated that the PLP 103-116 peptide bound to A(p) with slightly higher affinity than to A(q). Both A(q) and A(p) formed long-lived stable complexes (t(1/2)>24 h) with the PLP 103-116 peptide, but a higher amount of the peptide was loaded on to A(p) compared with A(q). An F2 gene segregation experiment, in which the low PLP 103-116 binding A(r) molecule and the high binding A(p) molecule could be compared for the influence on the disease susceptibility, indicated a role for both peptide binding affinity and non-MHC genes. Based on our results, we conclude that the H2-Ab gene controls severity of EAE but not necessarily the onset or type of disease course and that affinity of the disease-promoting peptide for the class II molecule is a critical pathogenic factor.

Binding stretches of myelin basic protein define encephalitogenic T cell epitopes for RT1.B and RT1.D alleles of four different rat haplotypes

Viruses could be involved in the induction of irnmunopathological events associated with multiple sclerosis (MS). For instance, molecular mimicry between viruses and myelin antigens could mediate cross-reactive immune responses leading to autoimmune disease. We previously showed that a human respiratory coronavirus (229E), and myelin basic protein (MBP) activated a large proportion of T-cell lines established from MS patients by in vitro selection with either 229E or MBP. We now report the generation and maintenance of T-cell clones specific for MBP, proteolipid protein (PLP) and the two known strains of human coronavirus (229E and OC43). Some of these clones were activated by both coronavirus and myelin antigens, which is consistent with molecular mimicry at the single T-cell level. The observation and further characterization of such T-cell clones will bring us closer to an understanding of their potential relevance in MS pathogenesis. (Supported by the Multiple Sclerosis Society of Canada) 1 7 0 Expansion by Self Antigen is Necessary for the Induction of Experimental Autoimmune Encephalomyelitis by T Cells Primed with a Cross-reactive Environmental Antigen A.M. Carrizosa. L.B. Nicholson, M. Farzan, HamardMedicalSchool, USA, S. Southwood, A. Sette, E pimmune, USA, R.A. Sobel, Stanford University School of Medicine, USA, V.K. Kuchroo, Harvard Medical School USA