EULAR study group on 'MHC-I-opathy': identifying disease-overarching mechanisms across disciplines and borders.

The 'MHC-I (major histocompatibility complex class I)-opathy' concept describes a family of inflammatory conditions with overlapping clinical manifestations and a strong genetic link to the MHC-I antigen presentation pathway. Classical MHC-I-opathies such as spondyloarthritis, Behçet's disease, psoriasis and birdshot uveitis are widely recognised for their strong association with certain MHC-I alleles and gene variants of the antigen processing aminopeptidases ERAP1 and ERAP2 that implicates altered MHC-I peptide presentation to CD8+T cells in the pathogenesis. Progress in understanding the cause and treatment of these disorders is hampered by patient phenotypic heterogeneity and lack of systematic investigation of the MHC-I pathway.Here, we discuss new insights into the biology of MHC-I-opathies that strongly advocate for disease-overarching and integrated molecular and clinical investigation to decipher underlying disease mechanisms. Because this requires transformative multidisciplinary collaboration, we introduce the EULAR study group on MHC-I-opathies to unite clinical expertise in rheumatology, dermatology and ophthalmology, with fundamental and translational researchers from multiple disciplines such as immunology, genomics and proteomics, alongside patient partners. We prioritise standardisation of disease phenotypes and scientific nomenclature and propose interdisciplinary genetic and translational studies to exploit emerging therapeutic strategies to understand MHC-I-mediated disease mechanisms. These collaborative efforts are required to address outstanding questions in the etiopathogenesis of MHC-I-opathies towards improving patient treatment and prognostication.

When it looks like Behçet's syndrome but is something else: differential diagnosis of Behçet's syndrome: a two-centre retrospective analysis.

OBJECTIVE: To investigate the differential diagnostic spectrum in patients with suspected Behçet's syndrome (BS) in low prevalence regions. In addition, the number of patients fulfilling the ICBD criteria despite not having BS was evaluated. METHODS: This retrospective analysis was performed in two referral centres for BS. Patients with confirmed BS (clinical diagnosis with fulfilment of ISG criteria or a score of ≥5 points in the ICBD criteria) were excluded. The remaining patients were divided into 11 differential diagnosis categories. If no definitive alternative diagnosis could be established, patients were termed 'probable BS' in case of (i) relapsing orogenital aphthosis in the absence of other causes and either HLA-B51 positivity, or origin from an endemic area or presence of an additional typical BS symptom that is not part of the classification criteria, or (ii) with 3-4 points scored in the ICBD criteria. RESULTS: In total 202 patients were included and categorized as follows: 58 patients (28.7%) as 'probable BS', 57 (28.2%) skin disease, 26 (12.9%) chronic pain syndrome, 14 (6.9%) eye disease, 11 (5.4%) spondyloarthropathy, 9 (4.5%) gastrointestinal disease, 7 (3.5%) neurological disease, 4 (2%) arthritis, 3 (1.5%) auto-inflammation, 3 (1.5%) connective tissue disease and 10 (5.0%) miscellaneous disease. HLA-B51 was positive in 55/132 (41.7%); 75/202 (37.1%) of the patients fulfilled the ICBD criteria. CONCLUSION: In a low disease prevalence setting, the straightforward application of the ICBD criteria may lead to overdiagnosis of BS. The differential diagnosis of BS is enormously broad. Clinicians should be aware that HLA-B51 positivity is still not considered as a diagnostic feature in BS.

Initial visit symptoms in probable Behçet's syndrome is predictive of ISG criteria fulfillment in Behçet's syndrome: data from New York and Amsterdam cohorts.

OBJECTIVES: Behçet's syndrome (BS) is a systemic vasculitis with heterogeneous clinical presentation and a relapsing disease course. The International Study Group (ISG) criteria are most often used for classification. A significant proportion of patients is classified as probable BS because they do not fulfil the criteria at initial presentation. The aim of this study is to explore clinical BS symptoms present at initial patient visit predictive of ISG criteria diagnosis during follow-up. METHODS: Patients classified as probable BS at initial visit were included. Follow-up ISG status (defined as meeting criteria ISG+ vs. not meeting criteria ISG-) was abstracted from last visit. Univariable logistic regression was used to screen initial visit clinical features and symptoms with follow-up ISG status. All variables that passed screening at p<0.10 were included in the final multivariable model, which was then used to create a probability risk score. RESULTS: 189 patients were included (169 from New York and 20 from Amsterdam). 71 (37.6%) patients were classified as ISG+ during follow-up. In the final model, presence of morning stiffness, genital ulcers, skin lesions, and eye disease were associated with increased odds of ISG+, adjusting for age, symptom duration and family history. This was used to create a probability risk score. CONCLUSIONS: Over a third of patients with suspected or probable BS developed new manifestations over time that led to classification as ISG+ BS. The presence of morning stiffness, genital ulcers, skin lesions and eye disease at initial visit were independently associated with significantly higher odds for developing ISG+ Behçet's during follow-up.

Adherence to guidelines for the treatment of Behçet's syndrome in New York and Amsterdam.

OBJECTIVES: To assess adherence to published guidelines for the treatment of Behçet's syndrome (BS) in two geographic areas. METHODS: We extracted guideline statements from the 2008 EULAR recommendations. Adherence to these statements was evaluated retrospectively in both New York (USA) and Amsterdam (The Netherlands), by reviewing records from patients fulfilling the ISG criteria. We analysed data per statement and event, and divided data according to the year in which an event occurred. We compared events prior to 2009 to those after publication of the EULAR recommendations (2009 and later). RESULTS: 474 patients were evaluated, 24 of whom were from Amsterdam. Treatment adherence varied substantially across various Behçet's manifestations, ranging from 21% vs. 31% in posterior uveitis, 50% vs. 25% in arterial disease, 29% vs. 29% in arthritis and 38% vs. 55% in erythema nodosum to 65% vs. 67% in deep venous thrombosis (DVT), before and after publication of the guidelines respectively. Topical treatment of mucocutaneous disease was only 2% vs. 8%, whereas adherence in neuro-Behçet was ≥ 94% and 100% in gastrointestinal disease. CONCLUSIONS: Adherence to treatment guidelines varies substantially by Behçet's manifestation. Lack of adherence in manifestations such as eye disease and arthritis suggests that current recommendations are not sufficient or other concurrent manifestations require more aggressive treatment. The extensive use of anti-TNF agents might indicate a shift towards more aggressive treatment. Thus, our results suggest the 2008 guidelines were not in line with treatment in clinical practice over the past years and the recent revision of the recommendations was indeed needed.

Reproducibility of Cutaneous Vascular Conductance Responses to Slow Local Heating Assessed Using seven-Laser Array Probes.

OBJECTIVE: Gradual local heating of the skin induces a largely NO-mediated vasodilatation. However, use of this assessment of microvascular health is limited because little is known about its reproducibility. METHODS: Healthy volunteers (n = 9) reported twice to the laboratory. CVC, derived from laser Doppler flux and mean arterial pressure, was examined in response to a standardized local heating protocol (0.5°C per 150 second from 33°C to 42°C, followed by 20 minutes at 44°C). Skin responses were examined at two locations on the forearm (between-site). Heating was repeated after a break of 24-72 hours (between-day). Reproducibility of skin responses at 33-42°C is presented for absolute CVC and relative CVC responses corrected for maximal CVC at 44°C (%CVCmax ). RESULTS: Between-day reproducibility of baseline CVC and %CVCmax for both sites was relatively poor (22-30%). At 42°C, CVC and %CVCmax responses showed less variation (9-19%), whilst absolute CVC responses at 44°C were 14-17%. Between-day variation for %CVCmax increased when using data from site 1 on day 1, but site 2 on the subsequent day (25%). CONCLUSION: Day-to-day reproducibility of baseline laser Doppler-derived skin perfusion responses is poor, but acceptable when absolute and relative skin perfusion to a local gradual heating protocol is utilized and site-to-site variation is minimized.