Relapsing Polychondritis and Large-vessel Vasculitis

Relapsing polychondritis: clinical updates and new differential diagnoses

Relapsing polychondritis is a rare inflammatory disease characterized by recurrent inflammation of cartilaginous structures, mainly of the ears, nose and respiratory tract, with a broad spectrum of accompanying systemic features. Despite its rarity, prompt recognition and accurate diagnosis of relapsing polychondritis is crucial for appropriate management and optimal outcomes. Our understanding of relapsing polychondritis has changed markedly in the past couple of years with the identification of three distinct patient clusters that have different clinical manifestations and prognostic outcomes. With the progress of pangenomic sequencing and the discovery of new somatic and monogenic autoinflammatory diseases, new differential diagnoses have emerged, notably the vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome, autoinflammatory diseases and immune checkpoint inhibitor-related adverse events. In this Review, we present a detailed update of the newly identified clusters and highlight red flags that should raise suspicion of these alternative diagnoses. The identification of these different clusters and mimickers has a direct impact on the management, follow-up and prognosis of patients with relapsing polychondritis and autoinflammatory syndromes.

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.

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.

Relapsing polychondritis: Best Practice & Clinical Rheumatology

Relapsing polychondritis (RP) is an uncommon inflammatory disorder that predominantly targets cartilaginous structures. The disease frequently affects the nose, ears, airways, and joints, but it can also impact organs that aren't primarily cartilage-based, such as blood vessels, skin, inner ear, and eyes. Given its infrequent occurrence and recurrent symptoms, patients often experience delays in proper diagnosis. Lately, based on the organs involved, the disease's diverse manifestations have been categorized into specific clinical groups, based on the most likely organ involvement including auricular, nasal, pulmonary, and musculoskeletal. More recently the discovery of a new disease, called (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) VEXAS syndrome, due to mutations in UBA1 gene, identified the cause of 8 % of the patients with a clinical diagnosis of RP. VEXAS is likely the cause of a previously described "hematologic subgroup" in RP. This discovery is proof of concept that RP is likely more than one disease (Beck et al., Dec 31 2020; Ferrada et al., 2021). People diagnosed with RP face numerous hurdles, with the quality of their lives and overall prognosis being affected. Diagnosing the condition is particularly challenging due to its fluctuating symptoms, the absence of specific markers, and the lack of universally recognized classification criteria. For a correct diagnosis, it's imperative for healthcare professionals to identify its unique clinical patterns. Moreover, there are no approved metrics to gauge the disease's severity, complicating patient management. This review seeks to equip clinicians with pertinent insights to better diagnose and attend to these complex patients.

Curcumin protects PC12 cells from a high glucose-induced inflammatory response by regulating the miR-218-5p/TLR4 axis

BACKGROUND

Curcumin exerts a protective effect on diabetic encephalopathy (DN), It is known for its potent neuroprotective, anti-inflammatory, antioxidant, and anticancer properties. However, the underlying mechanisms of curcumin's neuroprotective effects resulting from high glucose (HG)-induced injuries remain unknown. The purpose of this study is to identify the protective mechanism of Curcumin in the DN.

METHODS

In this study, pheochromocytoma cells (PC12 cells) were pretreated with different concentrations of Curcumin and then co-treated with Curcumin and glucose for 48 hours, and the cell viability was evaluated by CCK-8, the expression of the inflammatory mediators were detected by ELISA, the miR-218-5p and toll-like receptors (TLR4) level were examined by both quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting, the potential target genes of miR-218-5p were identified using luciferase reporter assay.

RESULTS

The viability of PC12 cells treated with HG was significantly reduced in a dose- and time-dependent manner. Cotreatment of curcumin with HG significantly increased cell viability. Curcumin inhibited the expression of the inflammatory mediators, tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), and induced the expression of the anti-inflammatory mediator interleukin-10 (IL-10). Curcumin upregulated the levels of miR-218-5p and downregulated the expression of TLR4 in HG-treated PC12 cells. The curcumin-induced anti-inflammatory effect was abrogated by a miR-218-5p inhibitor and overexpression of TLR4. The results suggest that curcumin ameliorates the inflammatory response by upregulating miR-218-5p levels in PC12 cells.

CONCLUSIONS

Our results indicate a protective role for curcumin in PC12 cells and suggest that it should be considered for the prophylactic treatment of DN in the future.

Curcumin ameliorates H2O2‑induced inflammatory response in chondrocytes by inducing autophagy activation

Relapsing polychondritis (RP) is a clinical disease characterized by inflammation of cartilage tissue and chondrocytes. The principal curcuminoid curcumin is the most active component in turmeric and has been reported to have a chondroprotective effect, including anti-inflammatory activity, which is vitally important for mitigating RP symptoms and prognosis. However, the mechanisms underlying these actions have remained to be fully elucidated. In the present study, the chondroprotective mechanisms of curcumin on hydrogen peroxide (H₂O₂)-treated primary chondrocytes were examined in vitro. The viability of chondrocytes treated with H₂O₂ was significantly reduced in a dose- and time-dependent manner. Cotreatment of curcumin with H₂O₂ significantly decreased growth inhibition. It was observed that curcumin inhibited the expression levels of the inflammatory mediators interleukin (IL)-1β, IL-6 and inducible nitric oxide synthase and induced autophagy activation. Curcumin increased the protein levels of the autophagy marker beclin-1 and light chain 3-II and decreased the expression levels of P62 in H₂O₂-treated chondrocytes. The curcumin-induced anti-inflammatory effects were markedly abrogated by the autophagy inhibitor 3-methyladenine. In conclusion, the present study suggested that curcumin regulates inflammatory factors by activating autophagy in chondrocytes. The protective role of curcumin in chondrocytes was demonstrated, suggesting that it should be explored for the prophylactic treatment of RP in the clinic in the future.

Relapsing Polychondritis Presenting 2 Years after Systemic Sclerosis with Pulmonary Arterial Hypertension

Relapsing polychondritis (RPC) is a systemic immune-mediated disease characterized by recurrent and progressive inflammation of cartilaginous tissues. 64% of RPC patients concurrent with other autoimmune disorders, there are very few reports about the concomitant RPC patients with systemic sclerosis (SSc). Herein we report a case of RPC in a 50-year-old female following SSc with pulmonary arterial hypertension (PAH) 2 years ago. She was treated with corticosteroids, immunosuppressive drugs, oral endothelin-A receptor antagonist and phosphodiesterase type 5 inhibitors. Her ocular and auricular symptoms disappeared quickly. The hemodynamic parameters were also significantly improved after treatment. To our knowledge, this is the first RPC complicated with SSc-PAH reported.