Cartilage destruction is partly induced by the internal proteolytic enzymes and apoptotic phenomenon of chondrocytes in relapsing polychondritis

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.

[Relapsing polychondritis]

Relapsing polychondritis (RP) is a rare multisystemic disease predominantly involving the extracellular matrix. Typical manifestations are chondritis of the ears, nose and trachea as well as an asymmetrical oligoarthritis or polyarthritis of small and also larger joints. Various other involvements have also been described. The treatment of RP is individually dependent on a variety of factors, e.g., organ manifestations. Glucocorticoids, immunosuppressants and targeted treatment are implemented. In the case of seronegative rheumatoid arthritis or vasculitis with an atypical course the symptoms of RP should be taken into consideration.

Innate immune responses in Behçet disease and relapsing polychondritis

Behçet disease (BD) and relapsing polychondritis (RP) are chronic multisystem disorders characterized by recurrent flare-ups of tissue inflammation. Major clinical manifestations of BD are oral aphthae, genital aphthous ulcers, skin lesions, arthritis, and uveitis. Patients with BD may develop rare but serious neural, intestinal, and vascular complications, with high relapse rates. Meanwhile, RP is characterized by the inflammation of the cartilaginous tissues of the ears, nose, peripheral joints, and tracheobronchial tree. Additionally, it affects the proteoglycan-rich structures in the eyes, inner ear, heart, blood vessels, and kidneys. The mouth and genital ulcers with inflamed cartilage (MAGIC) syndrome is a common characteristic of BD and RP. The immunopathology of these two diseases may be closely related. It is established that the genetic predisposition to BD is related to the human leukocyte antigen (HLA)-B51 gene. Skin histopathology demonstrates the overactivation of innate immunity, such as neutrophilic dermatitis/panniculitis, in patients with BD. Monocytes and neutrophils frequently infiltrate cartilaginous tissues of patients with RP. Somatic mutations in UBA1, which encodes a ubiquitylation-related enzyme, cause vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome (VEXAS) with severe systemic inflammation and activation of myeloid cells. VEXAS prompts auricular and/or nasal chondritis, with neutrophilic infiltration around the cartilage in 52-60% of patients. Thus, innate immune cells may play an important role in the initiation of inflammatory processes underlying both diseases. This review summarizes the recent advances in our understanding of the innate cell-mediated immunopathology of BD and RP, with a focus on the common and distinct features of these mechanisms.

Progress and challenges in the use of blood biomarkers in relapsing polychondritis

Relapsing polychondritis (RP) is a rare inflammatory disease with significant individual heterogeneity that involves systemic organs. The diagnosis of RP mainly depends on the clinical manifestations; currently, there are no molecular biomarkers routinely evaluated in clinical practice. Biomarkers have diagnostic or monitoring values and can predict response to treatment or the disease course. Over the years, many biomarkers have been proposed to facilitate diagnosis and prognosis. Unfortunately, ideal biomarkers to diagnose RP have not yet been discovered. Most of the molecular biomarkers in RP are immunological biomarkers, with autoantibodies and proteins related to cartilage damage in the blood being the most common. Alterations in some genes (HLA typing and UBA1 somatic mutation) were detected in patients with RP, which could serve as a potential biomarker for the diagnosis of RP. Moreover, proinflammatory cytokines and lymphocyte levels, and certain laboratory tests, have certain values of RP diagnosis and disease activity assessment but lack specificity and sensitivity. This review describes the different types of biomarkers and their clinical correlation with respect to the diagnosis of RP and disease activity. Research on biomarkers and disease pathology is ongoing to identify the ideal biomarkers that are sensitive and specific for RP.

Case Report: Lessons Learned From Subsequent Autologous and Allogeneic Hematopoietic Stem Cell Transplantations in a Pediatric Patient With Relapsing Polychondritis

Background

Autologous hematopoietic stem cell transplantation (autoHSCT) is increasingly being recognized as a treatment option for severe refractory autoimmune diseases (AD). However, efficacy is hampered by high relapse rates. In contrast, allogeneic HSCT (alloHSCT) has high potential to cure AD, but is associated with significant morbidity and mortality, and data in AD are limited. Experience with autoHSCT in relapsing polychondritis, a rare episodic inflammatory disorder characterized by destruction of cartilage, is scarce and alloHSCT has not been described before.

Case Presentation

Here, we present a case of a 9-year-old girl who was diagnosed with relapsing polychondritis, with severe airway involvement requiring a tracheostomy. The disease proved to be steroid-dependent and refractory to a wide array of disease-modifying anti-rheumatic drugs and biologicals. After an autoHSCT procedure, the disease became inactive for a short period of time, until the patient experienced a relapse after 31 days, accompanied by repopulation of effector/memory CD8⁺ T cells. Because of persistent inflammation and serious steroid toxicity, including severe osteoporosis, growth restriction, and excessive weight gain, the patient was offered an alloHSCT. She experienced transient antibody-mediated immune events post-alloHSCT, which subsided after rituximab. She ultimately developed a balanced immune reconstitution and is currently still in long-term disease remission, 8 years after alloHSCT.

Conclusion

This case adds to the few existing reports on autoHSCT in relapsing polychondritis and gives new insights in its pathogenesis, with a possible role for CD8⁺ T cells. Moreover, it is the first report of successful alloHSCT as a treatment for children with this severe autoimmune disease.

Mechanical model of steady-state and inflammatory conditions in patients with relapsing polychondritis: A review

Relapsing polychondritis (RP) is a multisystem inflammatory disorder, considered to associate with immune aberration.Increased T helper type-1 cell-related cytokines were reported in RP patients. mRNA expressions of a regulatory T cell cytokine interleukin (IL)-10 increased, whereas pro-inflammatory cytokines IL1β and IL6 mRNA expressions decreased in freshly isolated peripheral blood mononuclear cells of RP patients compared with those in healthy individuals. Upon in vitro stimulation with mitogen, IL10 mRNA expressions decreased, and IL1β and IL6 mRNA expressions increased in RP patients.This short-time dynamic change of gene expressions from anti-inflammatory to pro-inflammatory features of immune cells may be associated with the "relapsing" disease course of patients with RP. IL1β mRNA expressions of peripheral blood mononuclear cells exhibited positive correlations with serum matrix metalloproteinase (MMP)-3 concentrations in patients with respiratory involvement. Such positive correlation was not found in those without respiratory involvement.In a metagenomic analysis, an altered composition of gut microbes was found, suggesting that microbe metabolites such as short-chain fatty acids may affect T cell responses of the patients.In this review, the relationships among RP-related inflammatory molecules were summarized. The data support a hypothesis that the immune conditions are different between steady-state and inflammation in RP patients.

Serum MMP3 Correlated With IL1β Messenger RNA Expressions of Peripheral Blood Mononuclear Cells in Patients with Relapsing Polychondritis With Respiratory Involvement

OBJECTIVE

Respiratory involvement was intimately associated with poorer prognosis in patients with relapsing polychondritis (RP). We previously reported that high serum matrix metalloproteinase-3 (MMP3) was frequently observed in patients with RP with respiratory involvement. Elevated MMP3 secreted through local inflammation may be associated with the development of airway lesions.

METHODS

We collected peripheral blood mononuclear cells (PBMCs) and sera from 30 patients with RP and 14 healthy individuals. Interleukin (IL) 1β, IL6, and tumor necrosis factor (TNF) α messenger RNA (mRNA) expressions were analyzed in freshly isolated and cultured PBMCs with phytohemagglutinin and phorbol myristate acetate stimulation by real-time reverse transcription polymerase chain reaction and serum MMP3 by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We confirmed our previous finding that patients with respiratory involvements showed higher serum MMP3 compared with patients lacking respiratory involvement. IL1β mRNA expression was significantly higher in patients with RP than in healthy individuals after mitogenic stimulation. TNFα mRNA expression after stimulation was significantly lower in patients with RP compared with in healthy individuals. We performed correlation analyses between MMP3 and cytokine mRNA expressions in patients with RP. In patients with respiratory involvement, MMP3 correlated with IL1β and IL6 after stimulation. In patients without respiratory involvement, no positive correlations between MMP3 and cytokine mRNA expressions were observed regardless of culture condition. We did not find any positive correlations between MMP3 and TNFα mRNA expression in patients with RP.

CONCLUSION

It is possible that IL1β mRNA expression associates by some means with airway inflammation via the secretion of MMP3 in patients with RP. Involvement of proinflammatory cytokines, including IL1β, was suggested for the pathophysiology of airway lesions in patients with RP.

Respiratory subtype of relapsing polychondritis frequently presents as difficult asthma: a descriptive study of respiratory involvement in relapsing polychondritis with 13 patients from a single UK centre

Introduction

Relapsing polychondritis is a rare multisystem vasculitis characterised by recurrent cartilage inflammation. Respiratory involvement, of which tracheobronchomalacia (TBM) is the commonest form, is difficult to treat and is linked to increased mortality. We describe 13 patients with respiratory involvement.

Methods

This is a retrospective study of all the patients with relapsing polychondritis at University Hospitals Coventry and Warwickshire NHS Trust (UHCW), a secondary care provider for ∼500 000. Only patients with respiratory involvement were included in this study.

Results

We identified 13 patients who fulfilled the inclusion criteria. Most patients were identified from the “difficult asthma” clinic. TBM was seen in 11 patients, whilst two patients had pleural effusions which resolved with immunosuppression and one patient had small airways disease. Computed tomography scans (inspiratory and expiratory) and bronchoscopy findings were useful in diagnosing TBM. Pulmonary function testing revealed significant expiratory flow abnormalities. All patients were treated with corticosteroids/disease-modifying anti-rheumatic drugs (DMARDs) and some were given cyclophosphamide or biological agents, although the response to cyclophosphamide (1 out of 4) or biologicals (2 out of 4) was modest in this cohort. Ambulatory continuous positive airway pressure ventilation was successful in four patients.

Conclusions

Relapsing polychondritis may be overlooked in “difficult asthma” clinics with patients having TBM (not asthma) and other features of relapsing polychondritis. Awareness of this condition is crucial to enable early diagnosis and interventions to reduce the risk of life-threatening airway collapse. A number of patients respond well to DMARDs and are able to minimise corticosteroid use.

Tracheobronchomalacia can present as “difficult asthma” and can be associated with relapsing polychondritis. Optimal management of relapsing polychondritis is through medical treatments and support for the damaged airway through positive airway pressure.https://bit.ly/2JGoq23

Immunopathological findings in a cat with auricular chondritis

At clinical examination, a 5-year-old male domestic short-haired cat exhibited painful swelling and erythema of the pinnae of both ears. Microscopically, the lesions on both pinnae were composed of diffuse granulomatous chondritis with degeneration and necrosis of the pinnal cartilage. Numerous mast cells were also observed within and surrounding the inflammatory lesion. Immunohistochemistry showed a mixed inflammatory infiltrate characterised by the predominance of macrophages (CD68+, MAC 387+ and Lysozyme+), T lymphocytes (CD3+), some B lymphocytes (CD79α+) and neutrophils. Immunopathological characterisation of the lesion showed a granulomatous inflammation profile and suggests that the morphological changes and immunopathogenesis of auricular chondritis in cats presents a similarity with relapsing polychondritis in humans.

Case report of mixed-type autoimmune hemolytic anemia in a patient with relapsing polychondritis

RATIONALE

Relapsing polychondritis (RP) is a rare autoimmune-related disease and may be associated with other autoimmune diseases.

PATIENT CONCERNS

Here we reported a case of RP patients with mixed-type AIHA. The patient was diagnosed with RP in March 2008 which was treated and the patient was in stable condition. Laboratory data revealed progressive decrease in hemoglobin during her hospitalization due to pulmonary infection in 2016. Positive Coombs' test and moderate titer of anti-cold agglutinin was detected.

DIAGNOSIS

Mixed-type AIHA was diagnosed as a comorbidity in this case given the circumstance that her RP was stable and low-dose oral corticosteroids was enough to maintain remission.

INTERVENTIONS

The patient was treated with intravenous immunoglobulin and steroids.

OUTCOMES

The patient's body temperature dropped and hemoglobin levels rose in 2 weeks.

LESSONS

Reports of RP patients with autoimmune hemolytic anemia (AIHA) are extremely rare and cases with the mixed-type AIHA has not been reported. Here we describe a case of RP with mixed-type AIHA which was considered as a comorbidity rather than a complication.

Relapsing polychondritis patients were divided into three subgroups: patients with respiratory involvement (R subgroup), patients with auricular involvement (A subgroup), and overlapping patients with both involvements (O subgroup), and each group had distinctive clinical characteristics

Relapsing polychondritis (RP) is a multisystem disorder of cartilaginous tissues. Previously, we found that patients with respiratory involvement and patients with auricular involvement were mutually exclusive in the RP cohort, which suggests a strong inverse relationship between respiratory and auricular involvement. Here, we examined the clinical manifestation patterns in a subgroup of patients with respiratory involvement (R subgroup) and a subgroup of patients with auricular involvement (A subgroup) and investigated the clinical and laboratory characteristics of each subgroup.There were 47 patients (19.7%) and 118 patients (49.4%) allocated to the R and A subgroups, respectively. Saddle nose deformity and a progressive disease course were observed frequently in the R subgroup. Arthritis, conjunctivitis, and CNS involvement were observed frequently in the A subgroup.The remaining RP patients formed a third subgroup of patients that had both respiratory involvement and auricular involvement. We designated this subgroup as the O (overlap) subgroup, and 75 patients (31.4%) were allocated to the O subgroup. Disease duration in the O subgroup (5.70 ± 0.64 years) was significantly longer than that in the A subgroup (4.12 ± 0.45 years) and relatively longer than that in the R subgroup (4.80 ± 0.63 years).We found that cardiovascular involvement was more predominant in the O subgroup than in the R and A subgroups. Higher concentrations of serum matrix metalloproteinase (MMP)3 were observed in the O subgroup than in the R and A subgroups.We measured serum MMP3 concentrations in another patient cohort including 22 newly recruited RP patients. MMP3 concentrations were significantly higher in the O subgroup (n = 10) than those in the R subgroup (n = 6) and A subgroup (n = 10).RP patients in the R and A subgroups had different characteristics from each other, and the overlap of respiratory and auricular involvement was an important prognostic factor in patients with RP. Cardiovascular involvement was not observed in the R subgroup in RP patients. The current study may provide insights into the classification and treatment of RP.

Relapsing Polychondritis: An Updated Review

Relapsing polychondritis is an immune-mediated systemic disease characterized by recurrent episodes of inflammation of cartilaginous and proteoglycan-rich tissues, resulting in progressive anatomical deformation and functional impairment of the involved structures. Auricular and nasal chondritis and/or polyarthritis represent the most common clinical features, but potentially all types of cartilage may be involved. Because of the pleomorphic nature of the disease, with non-specific symptoms at the onset, the diagnosis of relapsing polychondritis is often delayed. In this review article we provide a comprehensive look into clinical presentation, laboratory and instrumental investigations, diagnostic criteria, and therapeutic options.

Refractory relapsing polychondritis: challenges and solutions

Relapsing polychondritis is a severe systemic immune-mediated disease characterized by an episodic and progressive inflammatory condition with progressive destruction of cartilaginous structures. This disease has for nearly a century kept secrets not yet explained. The real incidence and prevalence of this rare disease are unknown. The multiple clinical presentations and episodic nature of relapsing polychondritis cause a significant diagnosis delay. No guidelines for the management of patients with relapsing polychondritis have been validated to date. The challenges remain, both in the understanding of its pathophysiology and diagnosis, evaluation of its activity and prognosis, and its treatment. Possible solutions involve the sharing of data for relapsing polychondritis from worldwide reference centers. Thus, we would be able to evolve toward a better knowledge of its pathophysiology, the publication of new diagnosis criteria, which will include biological markers and imaging findings, the prediction of life-threatening or organ-threatening situations, and the publication of therapeutic evidence-based guidelines after performing at randomized controlled trials.

Efficacy of tocilizumab highlighted by FDG-PET/CT in a patient with relapsing polychondritis-associated aortitis

Relapsing polychondritis (RP) is a rare systemic inflammatory disease primarily affecting the ears, nose and tracheobronchial tree cartilage, but also the cardiovascular system. Cardiovascular complications are the second cause of mortality in RP. We report the case of a woman with a corticosteroid-resistant RP-associated aortitis, who was successfully treated with tocilizumab (TCZ). The FDG-PET/CT was a useful tool for diagnosing aortitis and assessing the effect of biotherapy. We conducted a systematic literature review confirming this is the first case of rapid and sustained remission in a patient with corticosteroid-resistant RP-associated aortitis after TCZ treatment administered as a first-line immunotherapy. However, further studies are needed to confirm the beneficial effect of TCZ used in this life-threatening condition.

Relapsing Polychondritis: A Review and Guide for the Dermatologist

Relapsing polychondritis, or RP, is a rare connective tissue disease characterized by relapsing-remitting destructive inflammation of the cartilaginous and other proteoglycan-rich structures in the body. Given the relatively low incidence of RP, a concise clinically relevant guide, focusing on the cutaneous manifestations of this serious disease, is lacking. In this review, we provide the dermatologist with an approach to diagnosing RP and a guide to its initial work-up, and management. We close with an overview of the currently available treatment modalities for RP.

A nationwide study of the epidemiology of relapsing polychondritis

OBJECTIVE

Relapsing polychondritis (RP) is a rare autoimmune inflammatory disease that attacks mainly cartilaginous structures or causes serious damage in proteoglycan-rich structures (the eyes, heart, blood vessels, inner ear). This study shows results regarding the epidemiology, progression, and associations of this highly variable disease by collecting all cases from a 124-million-person-year Central European nationwide cohort.

METHODS

We used the Hungarian Health Care Database to identify all persons with possible RP infection. We followed patients who had International Classification of Diseases 10th edition code M94.1 at least once in their inpatient or outpatient records between January 1, 2002 and December 31, 2013 in Hungary. We classified these patients into disease severity groups by their drug consumption patterns between January 1, 2010 and December 31, 2013. We analyzed the regional distribution of RP incidences as well. Overall maps of comorbidity are presented with network layouts.

RESULTS

We identified 256 patients with RP among cumulatively 11.5 million registered inhabitants. We classified these patients into four severity classes as "extremely mild" (n=144), "mild" (n=22), "moderate" (n=41), and "severe" (n=4). Two additional groups were defined for patients without available drug data as "suspected only" (n=23) and "confirmed but unknown treatment" (n=22). The age and sex distributions of patients were similar to worldwide statistics. Indeed, the overall survival was good (95% confidence interval for 5 years was 83.6%-92.9% and for 10 years was 75.0%-88.3% which corresponds to the overall survival of the general population in Hungary), and the associations with other autoimmune disorders were high (56%) in Hungary. Almost any disease can occur with RP; however, the symptoms of chromosomal abnormalities are only incidental. Spondylosis can be a sign of the activation of RP, while Sjögren syndrome is the most frequent autoimmune association. Regional distribution of incidences suggests arsenic drinking water and sunlight exposure as possible triggering factors.

CONCLUSION

The good survival rate of RP in Hungary is probably associated with the early diagnosis of the disease.

Relapsing Polychondritis: an Update on Pathogenesis, Clinical Features, Diagnostic Tools, and Therapeutic Perspectives

Relapsing polychondritis is a rare multisystemic disease widely accepted as a complex autoimmune disorder affecting proteoglycan-rich structures and cartilaginous tissues, especially the auricular pinna, cartilage of the nose, tracheobronchial tree, eyes, and heart's connective components. The clinical spectrum may vary from intermittent inflammatory episodes leading to unesthetic structural deformities to life-threatening cardiopulmonary manifestations, such as airway collapse and valvular regurgitation. The frequent association with other rheumatologic and hematologic disorders has been extensively reported over time, contributing to define its complexity at a diagnostic and also therapeutic level. Diagnosis of relapsing polychondritis is mainly based on clinical clues, while laboratory data have only a supportive contribution. Conversely, radiology is showing a relevant role in estimating the rate of systemic involvement as well as disease activity. The present review is aimed at providing an update on scientific data reported during the last 3 years about relapsing polychondritis in terms of pathogenesis, clinical features, diagnosis, and new treatment options.

Role of Fas and Treg cells in fracture healing as characterized in the fas-deficient (lpr) mouse model of lupus

Previous studies showed that loss of tumor necrosis factor α (TNFα) signaling delayed fracture healing by delaying chondrocyte apoptosis and cartilage resorption. Mechanistic studies showed that TNFα induced Fas expression within chondrocytes; however, the degree to which chondrocyte apoptosis is mediated by TNFα alone or dependent on the induction of Fas is unclear. This question was addressed by assessing fracture healing in Fas-deficient B6.MRL/Fas(lpr) /J mice. Loss of Fas delayed cartilage resorption but also lowered bone fraction in the calluses. The reduced bone fraction was related to elevated rates of coupled bone turnover in the B6.MRL/Fas(lpr) /J calluses, as evidenced by higher osteoclast numbers and increased osteogenesis. Analysis of the apoptotic marker caspase 3 showed fewer positive chondrocytes and osteoclasts in calluses of B6.MRL/Fas(lpr) /J mice. To determine if an active autoimmune state contributed to increased bone turnover, the levels of activated T cells and Treg cells were assessed. B6.MRL/Fas(lpr) /J mice had elevated Treg cells in both spleens and bones of B6.MRL/Fas(lpr) /J but decreased percentage of activated T cells in bone tissues. Fracture led to ∼30% to 60% systemic increase in Treg cells in both wild-type and B6.MRL/Fas(lpr) /J bone tissues during the period of cartilage formation and resorption but either decreased (wild type) or left unchanged (B6.MRL/Fas(lpr) /J) the numbers of activated T cells in bone. These results show that an active autoimmune state is inhibited during the period of cartilage resorption and suggest that iTreg cells play a functional role in this process. These data show that loss of Fas activity specifically in chondrocytes prolonged the life span of chondrocytes and that Fas synergized with TNFα signaling to mediate chondrocyte apoptosis. Conversely, loss of Fas systemically led to increased osteoclast numbers during later periods of fracture healing and increased osteogenesis. These findings suggest that retention of viable chondrocytes locally inhibits osteoclast activity or matrix proteolysis during cartilage resorption.

Relapsing polychondritis

Relapsing polychondritis (RP) is a rare disease in which recurrent bouts of inflammation, in some cases followed by destruction, affect the cartilage of the ears, nose, larynx, and tracheobronchial tree. At presentation, however, arthritis is the most common manifestation and more than half the patients have no evidence of chondritis. The subsequent development of chondritis provides the correct diagnosis in patients who present with polyarthritis, ocular inflammation, or skin or audiovestibular manifestations of unknown origin. A concomitant autoimmune disease is present in one-third of patients with RP. The pathogenesis of RP involves an autoimmune response to as yet unidentified cartilage antigens followed by cartilage matrix destruction by proteolytic enzymes. The diagnosis rests on clinical grounds and can benefit from use of Michet's criteria. Anti-collagen type II and anti-matrilin-1 antibodies are neither sensitive nor specific and consequently cannot be used for diagnostic purposes. In addition to the physical evaluation and laboratory tests, useful investigations include dynamic expiratory computed tomography, magnetic resonance imaging, Doppler echocardiography, and lung function tests. Bronchoscopy has been suggested as a helpful investigation but can worsen the respiratory dysfunction. The treatment of RP is not standardized. The drug regimen should be tailored to each individual patient based on disease activity and severity. Glucocorticoid therapy is the cornerstone of the treatment of RP and is used chronically in most patients. Immunosuppressive agents are given to patients with severe respiratory or vascular involvement and to those with steroid-resistant or steroid-dependent disease. Methotrexate is often effective. Cyclophosphamide is used in severe forms.

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.

Relapsing polychondritis complicated by giant cell myocarditis and myositis

An 83-year-old man presented with a three-week history of dyspnea. The clinical features suggested a diagnosis of relapsing polychondritis (RP); however, the patient died of heart failure. An autopsy revealed active chondritis of the tracheal and bronchial cartilage. Furthermore, giant cell myocarditis (GCM) and myositis were detected. To the best of our knowledge, this represents the first report of RP complicated by GCM and myositis. In patients with RP, GCM and myositis, CD163-positive macrophages and T-cells are most common, and the T-cell subset exhibits CD8 predominance. Common mechanisms of tissue damage caused by cytotoxic T-cells are likely to contribute to RP, GCM and myositis.

Reliability, reproducibility, and validation of five major histological scoring systems for experimental articular cartilage repair in the rabbit model

Histological evaluation of the repair tissue is a main pillar in the advancing field of experimental articular cartilage repair. Despite their widespread use, the major histological scoring systems for cartilage repair have seldom been validated. We tested the hypotheses (1) that elementary scores have a better reproducibility compared with more complex systems and (2) that the data from these different histological scores correlate with the DNA and proteoglycan contents of the repair tissue. A total of 1,165 observations of cartilage repair based on histological sections (n=233) from an experimental investigation on the repair of standardized osteochondral defects in vivo were made by three investigators with different levels of experience in cartilage research to determine the inter- and intra-observer reproducibility of elementary (Pineda and Wakitani score) and complex (O'Driscoll, Sellers, Fortier score) histological grading systems. DNA and proteoglycan contents of the repair tissues from simultaneously created defects were determined and correlated with histological (a) overall score values, (b) matrix staining, and (c) cellular characteristics of the five scores. Finally, applying the proteoglycan content as validating test, sensitivity, and specificity of the grading systems were assessed. All histological scores provided high intra- (Pearson r=0.92-0.99) and inter-observer reliability (intra-class correlation=0.94-0.99), low numerical intra- and inter-observer differences, and high internal correlations (Spearman's ρ=0.63-0.91). No disparity in reliability and reproducibility was detected between elementary and complex scores or between investigators with different levels of experience (all p>0.05). Individual histological overall score values did not correlate with proteoglycan contents but with DNA contents of the repair tissue (O'Driscoll, Wakitani, Sellers score). In all systems, proteoglycan contents did not correlate with matrix staining (all p>0.05), but histological cellular characteristics correlated with total cell numbers (p<0.001). These data indicate that both elementary and comprehensive histological scores are suited to quantify cartilage repair. Histological and biochemical evaluations may serve as complementary tools to assess articular cartilage repair in vivo.