Transgenic mouse models of rheumatoid arthritis

Evaluation of a fit-for-purpose assay to monitor antigen-specific functional CD4+ T-cell subpopulations in rheumatoid arthritis using flow cytometry-based peptide-MHC class-II tetramer staining

Antigen-specific T cells can serve as a response biomarker in non-clinical or clinical immunotherapy studies in autoimmune disease. There are protocols with optimized multimer staining methods to detect peptide (p)MHCII+ CD4+ T cells, and some qualified and validated protocols for pMHCI+ CD8+ T cells. However, no protocol is fully or partially qualified to enumerate and characterize antigen-specific pMHCII+ CD4+ T cells from patient samples. Implementing such an assay requires a desired level of specificity and precision, in terms of assay repeatability and reproducibility. In transgenic type II collagen (CII)-immunized HLA-DR1/DR4 humanized mouse models of collagen-induced arthritis (CIA), CII_259-273-specific T cells dominantly expand. Therefore antigen-specific T cells recognizing this epitope presented by rheumatoid arthritis (RA)-associated risk HLA-DR allomorphs are of interest to understand disease progression and responses to immunotherapy in RA patients. Using HLA-DRB1∗04:01 or ∗01:01-collagen type II (CII)_259–273 tetramers, we evaluated parameters influencing precision and reproducibility of an optimized flow cytometry–based method for antigen-specific CD4+ T cells and eight specific subpopulations with and without tetramer positivity. We evaluated specificity, precision, and reproducibility for research environments and non-regulated laboratories. The assay has excellent overall precision with %CV<25% for intra-assay repeatability, inter-analyst precision, and inter-assay reproducibility. The precision of the assay correlated negatively with the cell viability after thawing, indicating that post-thaw viability is a critical parameter for reproducibility. This assay is suitable for longitudinal analysis of treatment response and disease activity outcome in RA patients, and adaptable for translational or immunotherapy clinical trial settings.

Autoantigens in rheumatoid arthritis and the potential for antigen-specific tolerising immunotherapy

Autoimmune diseases, including rheumatoid arthritis, develop and persist due to impaired immune self-tolerance, which has evolved to regulate inflammatory responses to injury or infection. After diagnosis, patients rarely achieve drug-free remission, and although at-risk individuals can be identified with genotyping, antibody tests, and symptoms, rheumatoid arthritis cannot yet be successfully prevented. Precision medicine is increasingly offering solutions to diseases that were previously considered to be incurable, and immunotherapy has begun to achieve this aim in cancer. Comparatively, modulating autoantigen-specific immune responses with immunotherapy for the cure of autoimmune diseases is at a relatively immature stage. Current treatments using non-specific immune or inflammatory suppression increase susceptibility to infection, and are rarely curative. However, early stage clinical trials suggesting that immunotherapy might allow extended duration of remission and even prevention of progression to disease suggest modulating tolerance in rheumatoid arthritis could be a promising opportunity for therapy.

Kinetics of gene expression and bone remodelling in the clinical phase of collagen-induced arthritis

Introduction

Pathological bone changes differ considerably between inflammatory arthritic diseases and most studies have focused on bone erosion. Collagen-induced arthritis (CIA) is a model for rheumatoid arthritis, which, in addition to bone erosion, demonstrates bone formation at the time of clinical manifestations. The objective of this study was to use this model to characterise the histological and molecular changes in bone remodelling, and relate these to the clinical disease development.

Methods

A histological and gene expression profiling time-course study on bone remodelling in CIA was linked to onset of clinical symptoms. Global gene expression was studied with a gene chip array system.

Results

The main histopathological changes in bone structure and inflammation occurred during the first two weeks following the onset of clinical symptoms in the joint. Hereafter, the inflammation declined and remodelling of formed bone dominated.

Global gene expression profiling showed simultaneous upregulation of genes related to bone changes and inflammation in week 0 to 2 after onset of clinical disease. Furthermore, we observed time-dependent expression of genes involved in early and late osteoblast differentiation and function, which mirrored the histopathological bone changes. The differentially expressed genes belong to the bone morphogenetic pathway (BMP) and, in addition, include the osteoblast markers integrin-binding sialoprotein (Ibsp), bone gamma-carboxyglutamate protein (Bglap1), and secreted phosphoprotein 1 (Spp1). Pregnancy-associated protein A (Pappa) and periostin (Postn), differentially expressed in the early disease phase, are proposed to participate in bone formation, and we suggest that they play a role in early bone formation in the CIA model. Comparison to human genome-wide association studies (GWAS) revealed differential expression of several genes associated with human arthritis.

Conclusions

In the CIA model, bone formation in the joint starts shortly after onset of clinical symptoms, which results in bony fusion within one to two weeks. This makes it a candidate model for investigating the relationship between inflammation and bone formation in inflammatory arthritis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0531-7) contains supplementary material, which is available to authorized users.

Multifunctional T cell reactivity with native and glycosylated type II collagen in rheumatoid arthritis

OBJECTIVE

Type II collagen (CII) is a cartilage-specific protein to which a loss of immune tolerance may trigger autoimmune reactions and cause arthritis. The major T cell epitope on CII, amino acids 259-273, can be presented by several HLA-DRB1 04 alleles in its native or posttranslational glycosylated form. The present study was undertaken to functionally explore and compare CII-autoreactive T cells from blood and synovial fluid of patients with rheumatoid arthritis (RA).

METHODS

Peripheral blood was obtained from HLA-DRB1 04-positive RA patients (n = 10) and control subjects (n = 10) and stimulated in vitro with several variants of the CII(259-273) epitope, i.e., unmodified, glycosylated on Lys-264, glycosylated on Lys-270, or glycosylated on both Lys-264 and Lys-270. Up-regulation of CD154 was used to identify responding T cells. These cells were further characterized by intracellular staining for interleukin-17 (IL-17), interferon-γ (IFNγ), and IL-2 by flow cytometry. Synovial T cells from RA patients were investigated in parallel.

RESULTS

Multifunctional T cell responses toward all examined variants of the CII(259-273) peptide could be detected in RA patients and, to a lesser extent, also in healthy HLA-matched controls (P < 0.001). In RA patients, a comparison between blood- and joint-derived T cell function revealed a significant increase in levels of the proinflammatory cytokine IFNγ in synovial T cells (P = 0.027). Studies of longitudinally obtained samples showed that T cell responses were sustained over the course of disease, and even included epitope spreading.

CONCLUSION

The identification of inflammatory T cell responses to both glycosylated and nonglycosylated variants of the major CII epitope in RA patients suggests that CII autoreactivity in RA may be more common than previously recognized.

Plant-made pharmaceuticals for the prevention and treatment of autoimmune diseases: where are we?

Molecular farming in plants or plant cell cultures represents a viable alternative technology that holds great promise for the low-cost and large-scale production of recombinant proteins. The particular case of plant-based vaccines for the prevention of autoimmune diseases is addressed here, presenting a comprehensive overview of the different molecules and expression technologies that have been investigated so far in both academia and industry. The potential of plants not only as bioreactors but also as delivery systems for pharmaceuticals is discussed, and the advantages of oral delivery of autoantigens for the induction of immune tolerance are highlighted.

Predictivity and sensitivity of animal models of arthritis

Arthritis literally means joint inflammation. Arthritis is not a single disease. Arthritis refers to a group of rheumatic diseases and other conditions that can cause pain, stiffness and swelling in the joints. The forms range from those related to wear and tear of cartilage (such as osteoarthritis) to those associated with inflammation resulting from an overactive immune system (such as rheumatoid arthritis). Arthritis is more heterogeneous and this is an important starting point when discussing animal models for arthritis. Animal models are instrumental in understanding the etiology and pathogenetic mechanisms of rheumatoid arthritis. Several new mouse models have either been produced. Various methods have been applied to induce in animals experimental models of arthritis which would provide important insights into the aetiopathogenetic mechanisms of human RA.

Development and evaluation of transgenic rice seeds accumulating a type II-collagen tolerogenic peptide

Type II collagen (CII) in joint cartilage is known to be a major auto-antigen in human rheumatoid arthritis. Several animal model- and clinical-studies on tolerance-based immunotherapy for the arthritis have been conducted by administrating synthetic immunodominant peptides through an oral route. In the present study, to produce a tolerogenic peptide with therapeutic potential in transgenic rice plants, a gene construct producing glutelin fusion protein with tandem four repeats of a CII(250-270) peptide (residues 250-270) (GluA-4XCII(250-270)) containing a human T-cell epitope was introduced with a selection marker, hygromycin phosphotransferase gene (hygromycin-resistance gene) (hph), by co-transformation. Several transgenic plants with high and stable expression of gluA-4XCII ( 250-270 ), but no hph, were selected based on both DNA and protein analyses. The GluA-4XCII(250-270) fusion proteins were detected as both precursor and processed forms mainly in a glutelin fraction of rice endosperm protein extracts and in protein-body rich fractions prepared by density gradient ultracentrifugation. The amount of accumulated CII(250-270) peptide was immunochemically estimated to be about 1 microg per seed. Feeding DBA/1 mice the transgenic rice seeds (25 microg of the peptide per mouse a day) for 2 weeks showed tendencies lowering and delaying serum specific-IgG2a response against subsequent and repeated intraperitoneal-injection of type II collagen. Taken these together, the CII-immunodominant peptide could effectively be produced and accumulated as a glutelin-fusion protein in the transgenic rice seeds, which might be useful as pharmaceutical materials and functional food for prevention and therapy for anti-CII autoimmune diseases like human rheumatoid arthritis.

The impact of glycosylation on HLA-DR1-restricted T cell recognition of type II collagen in a mouse model

OBJECTIVE

Type II collagen (CII) is a candidate autoantigen implicated in the pathogenesis of rheumatoid arthritis (RA). Posttranslational glycosylation of CII could alter intracellular antigen processing, leading to the development of autoimmune T cell responses. To address this possibility, we studied the intracellular processing of CII for presentation of the arthritogenic glycosylated epitope CII(259-273) to CD4 T cells in macrophages from HLA-DR1-transgenic mice.

METHODS

HLA-DR1-transgenic mice were generated on a class II major histocompatibility complex-deficient background, and T cell hybridomas specific for the glycosylated and nonglycosylated epitope CII(259-273) were developed. Subcellular fractionation of macrophages was used to localize CII degradation to particular compartments and to identify the catalytic subtype of proteinases involved.

RESULTS

We showed that the glycosylated CII(259-273) epitope required more extensive processing than did the nonglycosylated form of the same epitope. Dense fractions containing lysosomes were primarily engaged in the processing of CII for antigen presentation, since these compartments contained 1) enzyme activity that generated antigenic CII fragments bearing the arthritogenic glycosylated epitope, 2) the antigenic CII fragments themselves, 3) CII peptide-receptive HLA-DR1 molecules, and 4) peptide/HLA-DR1 complexes that could directly activate T cell hybridomas. Degradation of CII by dense fractions occurred optimally at pH 4.5 and was abrogated by inhibitors of serine and cysteine proteinases.

CONCLUSION

Processing of the arthritogenic glycosylated CII(259-273) epitope, which is implicated in the induction of autoimmune arthritis, is more stringently regulated than is processing of the nonglycosylated form of the same epitope. Mechanisms of intracellular processing of the glycosylated epitope may constitute novel therapeutic targets for the treatment of RA.

Synthesis of Glycopeptides from Type II Collagen-Incorporating Galactosylated Hydroxylysine Mimetics and Their Use in Studying the Fine Specificity of Arthritogenic T Cells

Five analogues of the bovine type II collagen (bCII) immunodominant glycopeptide [beta-D-Gal-(5R)-5-Hyl264]CII(256-270) (1) carrying diverse modifications at the critical hydroxylysine (Hyl) 264 side chain were designed and synthesised, to explore the fine specificity of bCII-reactive T cells involved in the initiation and/or regulation of collagen-induced arthritis (CIA), a mouse model for rheumatoid arthritis (RA). Beta-D-galactosyl-(5R)-5-hydroxy-L-lysine (19) and corresponding mimetics (22-25), conveniently protected for solid-phase synthesis, were all obtained by a divergent route involving enantiopure 5-hydroxylated 6-oxo-1,2-piperidinedicarboxylates as the key intermediates. All three bCII-specific T hybridomas used, as well as a recurrent pathogenic CD4+ T-cell clone isolated from bCII-immunised DBA/1 mice, recognised the galactosylated form 1 of the immunodominant bCII (256-270) epitope. These cells were extremely sensitive to changes at the epsilon-amino group of Hyl264, but differed in their pattern of recognition of analogues with a Hyl264 side chain modified at C-5 (i.e. inversion of stereochemistry, methylation). These data further document the importance of collagen post-translational modifications in autoimmunity and in the CIA model in particular, and provide a new insight into the molecular interaction between glycopeptide 1 and the TCR of pathogenic T cells.

Tracking of Proinflammatory Collagen-Specific T Cells in Early and Late Collagen-Induced Arthritis in Humanized Mice

Rheumatoid arthritis is a chronic inflammatory disease associated with certain HLA-DR4 subtypes. The target autoantigen(s) is unknown, but type II collagen (CII) is a candidate, with a single immunodominant DR4-restricted 261-273 T cell epitope (CII(261-273)). In the present study, we have prepared HLA-DR4:CII(261-273) tetramers and analyzed peripheral blood, lymph node, and synovial fluid cells from DR4-transgenic mice with early and late collagen-induced arthritis to draw a fuller picture of the role of CII-reactive Th cells in disease development. Their frequencies increased approximately 20-fold in blood 1-2 wk postimmunization, and even more in acutely arthritic joints. Our data strongly suggest that CII-specific Th cells are necessary, but not sufficient for collagen-induced arthritis. The CII-specific Th cells displayed an activated proinflammatory Th1 phenotype, and their expansion correlated with onset and severity of arthritis and also with anti-CII Ab levels. Surprisingly, shortly after the first clinical signs of arthritis, activated HLA-DR4:CII tetramer(+) cells became undetectable in the synovial fluid and rare in the blood, but persisted in lymph nodes. Consequently, future human studies should focus on patients with early arthritis, and on their synovial cells, to re-evaluate the occurrence and pathogenic importance of CII-specific or other Th cells in rheumatoid arthritis.

What can the HLA transgenic mouse tell us about autoimmune diabetes?

Type 1 diabetes mellitus is a polygenic disease strongly associated with the class II molecules DR3, 4 and the linked DQ2, 8 alleles. These molecules play an important role in presentation of peptide antigens after intracellular processing to CD4 T lymphocytes. A number of in vitro approaches have been used to elucidate the molecular basis for the association of particular HLA alleles with susceptibility to or protection from Type 1 diabetes mellitus. These have focused on the structure of the antigen-presenting molecules, together with their peptides. Binding studies, peptide elution, molecular modelling and crystallisation of the peptide MHC complex have between them made it possible to define the peptide-binding regions and to examine the stability of binding of peptides from putative autoantigens. It is difficult to study the role of these molecules in vivo in humans, and HLA transgenic mice have been generated to overcome this problem. Studies of mice expressing the HLA class II alleles associated with diabetes have shown that the presence of HLA molecules alone does not cause disease except in the presence of an islet "insult", even when this "insult" would in itself be insufficient to precipitate disease in the absence of the HLA class II transgene. HLA transgenic mice offer a way to elucidate the in vivo role of these molecules, and could help the development of targeted immunotherapy.

The first synthesis of glucosylgalactosyl hydroxylysine (Glu-Gal-Hyl) an important biological indicator of collagen turnover

This paper reports the first chemical synthesis of alpha-D-glucopyranosyl-(1-->2)-beta-D-galactopyranosyl-O-hydroxylysine, a glycoside of hydroxylysine important as indicator of skin and bone collagen turnover, starting with commercial compounds.

Role of the galactosyl moiety of collagen glycopeptides for T-cell stimulation in a model for rheumatoid arthritis

Two protected derivatives of beta-D-galactopyranosyl-5-hydroxy-L-lysine, in which HO-4 of galactose has been O-methylated or replaced by fluorine, have been prepared. The building blocks were incorporated at position 264 of the peptide fragment CII259-273 from type II collagen by solid-phase synthesis. The ability of these two glycopeptides, and two CII259-273 glycopeptides in which HO-4 of galactose was either unmodified or deoxygenated, to elicit responses from T-cell hybridomas obtained in a mouse model for rheumatoid arthritis was then determined. The hybridomas were all highly sensitive towards modifications at C-4 of the beta-D-galactosyl residue of CII259-273, highlighting the role of HO-4 as an important contact point for the T-cell receptor. Most likely, this glycopeptide hydroxyl group is involved in hydrogen bonding with the T-cell receptor.

Glycopeptide specificity of helper T cells obtained in mouse models for rheumatoid arthritis

Five protected analogues of beta-D-galactosyl-(5R)-5-hydroxy-L-lysine were prepared, in which the galactosyl moiety was modified by monodeoxygenation or inversion of stereochemistry at C-4. The building blocks were used in the solid-phase synthesis of a set of glycopeptides related to the peptide fragment CII256-273 from type II collagen. Evaluation of the glycopeptides revealed that T-cell hybridomas obtained in collagen-induced arthritis (CIA), which is a common mouse model for rheumatoid arthritis, recognized the galactosyl moiety with high specificity for individual hydroxy groups. Moreover, T-cell hybridomas obtained in a humanized variant of CIA were also found to recognize the glycopeptides in an equally carbohydrate-specific manner. The results allowed the generation of models of the complexes formed between the appropriate class II major histocompatibility complex (MHC) molecule, glycopeptide, and the T-cell receptor, that is, of an interaction that is critical for the stimulation of T cells in the arthritis models. In the structural models, peptide side chains anchor the glycopeptide in pockets in the class II MHC molecule, whereas the galactosylated hydroxylysine residue forms the key contacts with the T-cell receptor. Importantly, the results also suggest that a T-cell response towards glycopeptide fragments from type II collagen could play an important role in the development of rheumatoid arthritis in humans.

Fc receptors are major mediators of antibody based inflammation in autoimmunity

There is now renewed interest in the role of antibodies in autoimmunity. Recent compelling evidence indicates that autoantibodies and the effector mechanisms they induce, for example, Fc receptor activation of leukocytes and/or the complement cascade, are central players in the development of autoimmunity, by perpetuating inflammation and perhaps even regulating the process itself. Of increasing interest are Fc receptors, which have been more closely investigated in the past decade using recombinant proteins, gene deficient mice and mouse models of human disease. These analyses point towards major roles of Fc receptors in antibody hypersensitivity reactions and by extension autoimmune disease, and they reveal opportunities in the development of novel therapeutic approaches in the treatment of autoimmune diseases.

Transgenic models of autoimmune disease

Transgenic and knockout mouse models have been invaluable for the elucidation of basic mechanisms in autoimmunity and have contributed new experimental models of human autoimmune diseases. Transgenic models of self tolerance have helped to change our view of this state from a process mediated purely by thymic deletion to a more complex process encompassing deletion, peripheral anergy, down-regulation of receptors and modulation by regulatory cells. Experiments in which the genes for the candidate target antigens in autoimmune disease are over-expressed or under-expressed have helped to clarify the targets of attack. Several examples of T cell receptor transgenic mice have been described in which T cells carry the receptor derived from a human or mouse autoimmune T cell clone. Such mice allow the characterization of T cell specificities contributing to disease and of the additional factors and checkpoints influencing disease development. In addition, the expression of disease associated HLA alleles in 'humanised' transgenic lines allows the mapping of HLA-restricted T cell epitopes and investigation of the mechanisms underlying these genetic associations. These approaches are leading to the generation of new disease models, offering hope for the design and testing of novel immunotherapeutic strategies.

The genetics of rheumatoid arthritis and the need for animal models to find and understand the underlying genes

The causes of rheumatoid arthritis (RA) are largely unknown. However, RA is most probably a multifactorial disease with contributions from genetic and environmental factors. Searches for genes that influence RA have been conducted in both human and experimental model materials. Both types of study have confirmed the polygenic inheritance of the disease. It has become clear that the features of RA complicate the human genetic studies. Animal models are therefore valuable tools for identifying genes and determining their pathogenic role in the disease. This is probably the fastest route towards unravelling the pathogenesisis of RA and developing new therapies.

Human autoimmunity genes in mice

In the post-genomic era, the expression and investigation of human (auto)immunity genes seems more relevant than ever. The generation of humanized animal models of human diseases will be useful to study the interplay between genetic and non-genetic factors in disease development and may form a basis for the development of new drugs that act more specifically than the ones currently in use. Transgenic mice have been generated that express various human proteins--candidate autoantigens, disease-associated MHC class II molecules, TCRs and/or CD4--in order to study diseases such as rheumatoid arthritis, multiple sclerosis and diabetes.

Synthesis of a C-glycoside analogue of beta-D-galactosyl hydroxynorvaline and its use in immunological studies

A C-linked isostere of beta-D-galactosylated hydroxynorvaline has been prepared in eight steps from per-O-benzylated galactopyranolactone. Addition of a homoallylic Grignard reagent to the lactone, reduction of the resulting hemiacetal with triethylsilane, and a Wittig reaction with Garner's aldehyde were key steps in this synthesis. The C-linked building block was then incorporated at position 264 into the fragment CII(256--270) from typeII collagen by solid-phase synthesis using a combination of the tert-butoxycarbonyl (Boc) and 9-fluorenylmethoxycarbonyl (Fmoc) protective group strategies. Deprotection of the benzylated C-linked galactosyl moiety was achieved simultaneously with cleavage of the glycopeptide from the solid phase by using triethylsilyl trifluoromethanesulfonate in TFA. Helper T-cell hybridomas obtained in a mouse model for rheumatoid arthritis responded to the C-linked glycopeptide when presented by classII MHC molecules. However, 10- to 20-fold higher concentrations were required as compared to when O-linked beta-D-galactosylated hydroxynorvaline or hydroxylysine (Hyl) were present at position 264 of CII(256--270). Thus, replacement of a single oxygen atom by a methylene group in the carbohydrate moiety of a glycopeptide antigen had a substantial influence on the T-cell response. This reveals that T cells are able to recognize the carbohydrate moiety of glycopeptide antigens with high specificity. Finally, the results suggest that structural modifications of beta-D-Gal-Hyl(264) in CII(256--270) may give altered peptide ligands that can be used for induction of tolerance in autoimmune rheumatoid arthritis.

Association of MHC and rheumatoid arthritis. HLA-DR4 and rheumatoid arthritis: studies in mice and men

Inherited susceptibility to rheumatoid arthritis (RA) is associated with the DRB1 genes encoding the human leukocyte antigen (HLA)-DR4 and HLA-DR1 molecules. Transgenic mice expressing these major histocompatibility complex (MHC) class II molecules have been developed to generate humanized models for RA. The relevance of these models for understanding RA will be discussed.

T cells that are naturally tolerant to cartilage-derived type II collagen are involved in the development of collagen-induced arthritis

The immunodominant T-cell epitope that is involved in collagen-induced arthritis (CIA) is the glycosylated type II collagen (CII) peptide 256-270. In CII transgenic mice, which express the immunodominant CII 256-270 epitope in cartilage, the CII-specific T cells are characterized by a partially tolerant state with low proliferative activity in vitro, but with maintained effector functions, such as IFN-gamma secretion and ability to provide B cell help. These mice were still susceptible to CIA. The response was mainly directed to the glycosylated form of the CII 256-270 peptide, rather than to the nonglycosylated peptide. Tolerance induction was rapid; transferred T cells encountered CII within a few days. CII immunization several weeks after thymectomy of the mice did not change their susceptibility to arthritis or the induction of partial T-cell tolerance, excluding a role for recent thymic emigrants. Thus, partially tolerant CII autoreactive T cells are maintained and are crucial for the development of CIA.