Tom J. Goldschmidt

Collagen induced arthritis as an experimental model for rheumatoid arthritis

The type II collagen (CII) induced arthritis animal model (CIA) provides opportunities to study the nature of autoimmune reactions leading to arthritis and may be used as a model for rheumatoid arthritis (RA). Thus, in similarity with RA, the CIA model, when induced with autologous CII, shows a chronic and progressive disease course. The susceptibility to both RA and CIA are correlated to the expression of certain MHC class II allotype genes. In both diseases are autoantibodies to CII and rheumatoid factors produced. Immunohistopathology of affected joints show in both diseases a dominance of activated macrophages/fibroblasts with a significant infiltration of activated T cells and an infiltration of granulocytes. We do here suggest that both RA and CIA are dependent on a synergy between delayed type hypersensitivity and immune complex mediated inflammarory mechanisems and that CIA provides opportunities for studies of immunspecific reactions leading to arthritis.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) alters intrathymic T-cell development in mice

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was administered to 2-4-week-old mice (5, 25, and 50 micrograms/kg body wt.) and to in vitro cultures (10(-9) M) of fetal thymi. By monitoring thymocyte populations with respect to the differentiation antigens CD4 and CD8, it was found that the cell number in all thymocyte populations except for CD8+ decreased significantly compared with controls. In vivo the most marked decrease occurred among double negative (DN) and double positive (DP) cells, whereas in vitro, the DP cells were most severely affected. The cell number had already decreased to some extent by day 1 after a dose of 50 micrograms/kg body wt. of TCDD, although a severe reduction did not become apparent until day 4. There was a clear dose/response relationship between 5 and 50 micrograms/kg body wt. Autoradiography and liquid scintillation counting studies showed that incorporation of [3H]thymidine in the thymus had already decreased 24 h after TCDD treatment, with the decrease being even more pronounced at 48 h. By 96 h, the rate of cell proliferation had returned to approximately normal values. The results show that TCDD has a long-lasting effect on thymocyte abundance together with a transient effect on cell proliferation. This indicates that in addition to the initial effects of TCDD on cell proliferation, it may also more permanently disturb the normal process of elimination by means of selection.

Homologous collagen-induced arthritis in rats and mice are associated with structurally different major histocompatibility complex DQ-like molecules.

Collagen‐induced arthritis (CIA) in rats, induced with homologous type II collagen (CII), is a genetically more restricted disease and has better resemblance to rheumatoid arthritis by its chronic disease course, than CIA induced with heterologous CII. The DA strain is highly susceptible to CIA induced with homologous CII, while the Lewis strain is resistant. (DAxLew)F1 is susceptible and backcrossing to Lewis reveals a close, but not complete, association of both arthritis and CII responsiveness to the RT1a haplotype. Analyses of congenic strains on DA and Lewis backgrounds suggest that expression of a major histocompatibility complex class II Ba molecule, encoded from the RT1Ba locus, is associated with arthritis susceptibility and CII responsiveness. The second exons coding for the first domains of the α and β chains of both the RT1a and RT11 haplotypes were sequenced and the deduced amino acid sequences compared with the corresponding molecule associated with susceptibility to CIA in the mouse (H‐2 Aq). The sequences of the respective alleles revealed no obvious structural homology explaining the extensive similarities in the development of chronic autoimmune arthritis. Instead, this finding implies that different trimolecular constituents (i.e. class II,T cell receptor, and CII peptides) may yield an antigen presentation event that is able to trigger a similar autoaggressiveness in the two rodent species.

Oestrogen-mediated suppression of collagen-induced arthritis in rats. Studies on the role of the thymus and of peripheral CD8+ T lymphocytes.

Administration or oestrogen to castrated female rats has previously been shown to exert a suppressive effect both on the development of collagen‐induced arthritis (CIA) and on the delayed‐type hypersensitivity (DTH) reaction to collagen II (CII). The present study is concerned with the mechanisms responsible for this suppression, particularly as to the role of the thymus and the CD8+ T lymphocytes; both the thymic epithelial cells and the CD8+ T cells have earlier been implicated as responsible for oestrogen‐mediated immunomodulation on the basis of their expression of oestrogen receptors. Adult thymectomy alone did not affect either the incidence or severity of arthritis. Furthermore, adult thymectomy did not change the observed suppressive effects of oestrogen treatment on arthritis development or auto‐anti‐CII T‐cell immunity. Elimination of CD8+ T cells was subsequently achieved in groups of thymectomized rats by utilizing the fact that efficient depletion of CD8+ T cells occurs after in vivo treatment with OX8 monoclonal antibodies; depletion of peripheral CD8+ T cells failed to influence the suppressive effect of oestrogen on CIA and on the in vitro proliferate response of lymph‐node cells to‐CII. Depletion of CD8+ T cells did, however, in itself reduce the incidence of CIA in non‐oestrogen‐treated and thymectomized rats. We conclude that oestrogen may exert its suppressive effect on development of CIA and on T‐cell responsiveness via mechanisms independent of both the thymus and the CD8+ T‐cell subpopulation, but that CD8+ T cells are nevertheless involved in the regulation and/or effectuation of the immune reactions responsible for development of collagen arthritis in rats.

Depletion of murine T cells by in vivo monoclonal antibody treatment is enhanced by adding an autologous anti-rat κ chain antibody

In vivo treatment with monoclonal antibodies can be used for elimination of various T lymphocyte subsets from peripheral lymphoid organs and blood and thereby be used both to analyze the role of different T cells in immunoregulation and for the treatment of experimental immunological diseases. However, one problem with this approach has been that not all monoclonal antibodies given in vivo eliminate their target cells. We now show in the murine system that the normally inefficiently depleting H129.19 (anti-CD4) and 53.6.7 (anti-CD8) antibodies can be used for efficient depletion of their respective target cells when combined with injection of a secondary mouse anti-rat kappa (MAR18.5) antibody. The efficacy of the depletion protocols was ascertained by double staining techniques and cytofluorometric analysis. It is suggested that the presently used sandwich method applying a homologous secondary monoclonal antibody may provide an alternative to class switching or other manipulations of primary antibodies in increasing the efficacy of in vivo antibody treatment.

Activated Type II Collagen Reactive T Cells are not Eliminated by in vivo Anti-CD4 Treatment. Implications for Therapeutic Approaches on Autoimmune Arthritis

Activation of CD4+ T cells plays an important role in type II collagen (CII) induced arthritis (CIA). The CD4+ T cell dependency is demonstrated by anti-CD4 antibody treatment which suppresses CIA in mice if injected before CII immunization. The same anti-CD4 treatment at a later stage does not suppress CIA, despite extensive elimination of peripheral CD4+ T cells. A possible explanation for this discrepancy is that activated T cells might not be as easily influenced by the anti-CD4 antibodies as resting T cells. To address this question, the proliferative capacity of CII reactive CD4+ lymph node (LN) T cells, in mice treated with anti-CD4 antibodies before or after the CII immunization, was analyzed. In mice treated before immunization the capacity of LN cells to proliferate in vitro was markedly suppressed while in mice receiving anti-CD4 treatment after immunization it was retained. Flow cytometric analysis revealed that the anti-CD4 treatment before and after immunization reduced the number of CD4+ LN T cells to the same level. The small population of CD4+ LN cells which were left after anti-CD4 treatment of naive mice all expressed CD44, a marker for previously activated T cells in mice. We propose that activation render CII reactive T cells more resistant to anti-CD4 treatment than virgin T cells are and suggest that the lack of therapeutic effect of late anti-CD4 treatment in CIA does not necessarily implicate that CD4+ T cells are unimportant in that stage of the disease.

Immunoregulation in Arthritis: A Review on Synovial Immune Reactions in RA and in Some Experimental Animal Models for Arthritis

Local synovial immune reactions have during recent years been characterized both in human arthritides, particularly in rheumatoid arthritis (RA), and in animal models for arthritis. Common characteristics of human RA on one hand and experimental adjuvant arthritis and collagen arthritis on the other hand, are induced expression of class II transplantation antigens on synovial cells close to the cartilage and presence of activated T lymphocytes in close proximity to these class II expressing cells. The present review aims to describe some implications of these and subsequent findings both concerning the analysis of the pathogenesis of RA and concerning some therapeutic implications derived from parallel studies on relevant features of the human RA and the respective animal models for arthritis.