Mice expressing HLA-DQ6alpha8beta transgenes develop polychondritis spontaneously

Autoimmunity and Autoinflammation: Relapsing Polychondritis and VEXAS Syndrome Challenge

Relapsing polychondritis is a chronic autoimmune inflammatory condition characterized by recurrent episodes of inflammation at the level of cartilaginous structures and tissues rich in proteoglycans. The pathogenesis of the disease is complex and still incompletely elucidated. The data support the important role of a particular genetic predisposition, with HLA-DR4 being considered an allele that confers a major risk of disease occurrence. Environmental factors, mechanical, chemical or infectious, act as triggers in the development of clinical manifestations, causing the degradation of proteins and the release of cryptic cartilage antigens. Both humoral and cellular immunity play essential roles in the occurrence and perpetuation of autoimmunity and inflammation. Autoantibodies anti-type II, IX and XI collagens, anti-matrilin-1 and anti-COMPs (cartilage oligomeric matrix proteins) have been highlighted in increased titers, being correlated with disease activity and considered prognostic factors. Innate immunity cells, neutrophils, monocytes, macrophages, natural killer lymphocytes and eosinophils have been found in the perichondrium and cartilage, together with activated antigen-presenting cells, C3 deposits and immunoglobulins. Also, T cells play a decisive role in the pathogenesis of the disease, with relapsing polychondritis being considered a TH1-mediated condition. Thus, increased secretions of interferon γ, interleukin (IL)-12 and IL-2 have been highlighted. The "inflammatory storm" formed by a complex network of pro-inflammatory cytokines and chemokines actively modulates the recruitment and infiltration of various cells, with cartilage being a source of antigens. Along with RP, VEXAS syndrome, another systemic autoimmune disease with genetic determinism, has an etiopathogenesis that is still incompletely known, and it involves the activation of the innate immune system through different pathways and the appearance of the cytokine storm. The clinical manifestations of VEXAS syndrome include an inflammatory phenotype often similar to that of RP, which raises diagnostic problems. The management of RP and VEXAS syndrome includes common immunosuppressive therapies whose main goal is to control systemic inflammatory manifestations. The objective of this paper is to detail the main etiopathogenetic mechanisms of a rare disease, summarizing the latest data and presenting the distinct features of these mechanisms.

HLA transgenic mice: application in reproducing idiosyncratic drug toxicity

Various types of transgenic mice carrying either class I or II human leukocyte antigen (HLA) molecules are readily available, and reports describing their use in a variety of studies have been published for more than 30 years. Examples of their use include the discovery of HLA-specific antigens against viral infection as well as the reproduction of HLA-mediated autoimmune diseases for the development of therapeutic strategies. Recently, HLA transgenic mice have been used to reproduce HLA-mediated idiosyncratic drug toxicity (IDT), a rare and unpredictable adverse drug reaction that can result in death. For example, abacavir-induced IDT has successfully been reproduced in HLA-B*57:01 transgenic mice. Several reports using HLA transgenic mice for IDT have proven the utility of this concept for the evaluation of IDT using various HLA allele combinations and drugs. It has become apparent that such models may be a valuable tool to investigate the mechanisms underlying HLA-mediated IDT. This review summarizes the latest findings in the area of HLA transgenic mouse models and discusses the current challenges that must be overcome to maximize the potential of this unique animal model.

Relapsing polychondritis, an underestimated dermatological urgency: case report and literature review

BACKGROUND

Relapsing polychondritis is an autoimmune multisystemic disease with primary chondral involvement. Its high mortality and morbidity make it a real clinical challenge.

CASE DESCRIPTION

A 32-year-old woman with a history of relapsing polychondritis, refractory to multiple treatments, with multisystem compromise, imminent risk of death due to severe tracheobronchial damage and difficult ventilatory support, and successful treatment with infliximab.

DISCUSSION AND EVALUATION

Several treatments have been described in the literature, such as nonsteroidal anti-inflammatory drugs, corticosteroids, dapsone, azathioprine, cyclosporine, cyclophosphamide, and methotrexate. However, the cases refractory to conventional therapy may lead to chronicity, irreversibility, and death. As a result, a third-line therapy could improve the prognosis of these patients.

CONCLUSIONS

Biological therapy is a good option for disease control and quality of life improvement. In addition, the physician should consider these treatments to avoid the chronicity and risk of death of these patients.

Auricular Chondritis Caused by Metal Ear Tagging in C57BL/6 Mice

Although it has been shown that auricular chondritis in rats is caused by the use of metal identification ear tags, the pathogenesis remains unclear. Based on the hypothesis that the auricular chondritis is caused by metal ions released from metal identification ear tags, we investigated the pathogenesis in male C57BL/6 mice tagged with metal identification ear tags. Twenty-six weeks after the attachment of the ear tags, visible increases in the thickness of the auricle were observed, and the concentrations of copper and iron in the tagged ears were significantly increased ( P <.05) in the tagged ears compared with the untagged ears. There was up-regulation of metallothionein (MT)-I and MT-II mRNA in the tagged ears, and this was confirmed by immunohistologic staining of the destroyed cartilage. Histopathologically, there were observed severe chondritis with extensive granulomatous inflammation, newly formed cartilage nodules, and osseous metaplasia accompanied by cellular infiltrates, such as CD4 T lymphocyte, macrophages, neutrophils, and mast cells, and expression of Th1 cytokines, such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-2 in the tagged ear. Based on these results, we concluded that the release of copper and iron ions from the metal ear tags played a major role in the onset of auricular chondritis. Subsequent cellular interactions, such as CD4 T cells, macrophages, fibroblasts, and mast cells, mediated by cytokines, such as tumor necrosis factor-alpha and interferon-gamma, caused an autoimmune response that may have led to the progression of auricular chondritis as an autoimmune disease.

A Case of Bilateral Auricular Chondritis in a Heifer

Auricular chondritis is an extremely rare condition in cattle and other domestic animals. A 13-month-old Jersey heifer was presented with cutaneous papillomatosis and bilaterally droopy ears. Histopathology revealed bilateral auricular chondritis characterized by lymphoplasmacytic infiltrate and extensive destruction and fibrosis of the auricular cartilage.

Pathogenesis of relapsing polychondritis: a 2013 update

Relapsing polychondritis (RP) is a systemic inflammatory disease primarily affecting not only the cartilaginous structures of the ears, nose and tracheobronchial tree but also the joints, the inner ear, the eyes, and the cardiovascular system. RP is an immune-mediated disease during which target antigens are still unknown, but data from human studies and murine models strongly support a role of both Collagen Type II (CII) and matrilin-1 as potential candidates. RP is likely a Th1-mediated disease as serum levels of interferon (IFN)-γ, interleukin [IL]-12, and IL-2 parallel changes in disease activity, while the levels of Th2 cytokines do not. Serum levels of sTREM-1, interferon-γ, CCL4, vascular endothelial growth factor, and matrix metalloproteinases-3 are significantly higher in RP patients than in healthy donors, with sTREM-1 correlating with disease activity. Patients with active RP also have significantly higher levels of MCP-1, MIP-1β, MIF, and IL-8 than controls. These pro-inflammatory chemokines are involved in the modulation and recruitment of monocytes and neutrophils. Altogether, these data suggest that a complex cytokine network orchestrates the recruitment of infiltrating cells in RP lesions. Cytokine modulation using TNFα blockers, rituximab, anakinra, tocilizumab, and abatacept has recently been shown effective in some RP cases but further data are needed. Better understanding of the repertoire of infiltrating cells may provide interesting clues to further define the putative RP auto-antigens. Study of circulating mononuclear cells during RP flares may also provide crucial information about the ongoing cellular trafficking and recruitment processes involved in this rare disease.

Trans heterodimer between two non-arthritis-associated HLA alleles can predispose to arthritis in humanized mice

OBJECTIVE

Certain HLA class II alleles are associated with susceptibility to the development of arthritis. However, the development of arthritis in some persons carrying non-rheumatoid arthritis (RA)-associated alleles remains unexplained. An individual who is heterozygous for the DQA1 and DQB1 genes can express the DQ molecule in cis or trans heterodimers. In a cis heterodimer, the α-chain interacts with the β-chain coded by the same chromosome, while in a trans heterodimer it interacts with the β-chain on the other chromosome. In this study, we used a humanized mouse model of arthritis in an attempt to determine whether a trans heterodimer of 2 nonassociated alleles, DQB1*0601 and DQB1*0604, can predispose to arthritis.

METHODS

DQB1*0601 and *0604 occur in linkage with DQA1*0103 and *0102, respectively. To understand the role of trans heterodimers, we generated DQB1*0604/DQA1*0103-transgenic mice lacking endogenous HLA class II molecules.

RESULTS

Severe arthritis developed in the DQB1*0604/A1*0103-trangenic mice, and an antigen-specific response was generated in vitro. DQB1*0604/DQA1*0103 presented type II collagen-derived peptides that were not presented by the arthritis-resistant DQB1*0601 allele, suggesting that trans heterodimer molecules between 2 DQB1 and DQA1 molecules may result in the presentation of unique antigens and susceptibility to the development of arthritis. Molecular modeling of type II collagen peptides showed that DQB1*0604/DQA1*0103 shares a p4 pocket with the arthritis-susceptible DQB1*0302 allele, suggesting a critical role of the p4 and p9 pockets in susceptibility to arthritis.

CONCLUSION

These results provide a possible explanation for the parental inheritance of nonsusceptibility alleles in some patients with RA and a mechanism by which they can predispose to the development of arthritis.

Vaccination with collagen-pulsed dendritic cells prevents the onset and reduces the disease severity in the mouse model of spontaneous polychondritis

Immature dendritic cells (iDCs) have a tolerogenic potential due to low expression of important co-stimulatory cell surface molecules required for antigen presentation and induction of an effective immune response. We report here that injection of iDCs pulsed with chick type II collagen (CII) delayed the onset significantly and suppressed the severity of spontaneous polychondritis (SP) in the human leucocyte antigen (HLA)-DQ6alphabeta8alphabeta transgenic mouse model. Bone marrow-derived iDCs were pulsed in vitro with CII and transferred into 6-week-old HLA-DQ6alphabeta8alphabeta transgenic mice. Mice receiving CII-pulsed iDCs did not display any clinical signs of disease until 5.5 months of age, indicating the ability of the DC vaccine to delay significantly the onset of SP. Control groups receiving unpulsed iDCs or phosphate-buffered saline (PBS) developed polyarthritis at 3.5 months, as we have reported previously. The severity and incidence of disease was reduced in mice injected with CII-pulsed iDCs. Proinflammatory cytokines were in low to undetectable levels in the serum and tissue in the CII-pulsed iDC mice, correlating with the protection. This is the first evidence of iDC therapy controlling SP and suggests that iDC vaccination may provide a tool to reducing clinical manifestations in human inflammatory autoimmune disease such as relapsing polychondritis and rheumatoid arthritis.

HLA class II transgenic mice mimic human inflammatory diseases

Population studies have shown that among all the genetic factors linked with autoimmune disease development, MHC class II genes on chromosome 6 accounts for majority of familial clustering in the common autoimmune diseases. Despite the highly polymorphic nature of HLA class II genes, majority of autoimmune diseases are linked to a limited set of class II-DR or -DQ alleles. Thus a more detailed study of these HLA-DR and -DQ alleles were needed to understand their role in genetic predisposition and pathogenesis of autoimmune diseases. Although in vitro studies using class-II restricted CD4 T cells and purified class II molecules have helped us in understanding some aspects of HLA class-II association with disease, it is difficult to study the role of class II genes in vivo because of heterogeneity of human population, complexity of MHC, and strong linkage disequilibrium among different class II genes. To overcome this problem, we pioneered the generation of HLA-class II transgenic mice to study role of these molecule in inflammatory disease. These HLA class II transgenic mice were used to develop novel in vivo disease model for common autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, insulin-dependent diabetes mellitus, myasthenia gravis, celiac disease, autoimmune relapsing polychondritis, autoimmune myocarditis, thyroiditis, uveitis, as well as other inflammatory disease such as allergy, tuberculosis and toxic shock syndrome. As the T-cell repertoire in these humanized HLA transgenic mice are shaped by human class II molecules, they show the same HLA restriction as humans, implicate potential triggering mechanism and autoantigens, and identify similar antigenic epitopes seen in human. This review describes the value of these humanized transgenic mice in deciphering role of HLA class II molecules in immunopathogenesis of inflammatory diseases.