Clinicians have long assumed that an association exists between crystal arthropathies and the presence of osteoarthritis (OA). However, studies establishing an independent association between calcium pyrophosphate or uric acid crystal disease and OA are sparse. Even less is known about a possible pathogenic relationship. Whereas some studies suggest that the relationships between crystals and OA may not be incidental and that crystal deposition may contribute to the onset and/or acceleration of OA joint damage, other authors have challenged this assertion. In this review, we provide an overview of past and current research elucidating the role of crystal deposition, including monosodium urate, calcium pyrophosphate, and other crystals, in OA. Given the clinical frequency of gout and that agents exist to modulate serum UA levels, special attention is given to the role of monosodium urate crystals.

Overall, our findings underline the potential of targeted CD11b ligation on human dendritic cells for the engineering of suppressive immunotherapy for Th17-related autoimmune disorders.

A 40-year-old Chinese man was admitted for haemoptysis and progressive deep vein thrombosis involving the inferior vena cava (IVC) despite anticoagulation. An IVC filter had been placed earlier at an outside hospital. CT angiography revealed two pulmonary artery aneurysms. The patient was found to have a history of oral and genital ulcers, uveitis and erythema nodosum, thus meeting criteria for Behçet's disease. Other causes of the haemoptysis and thrombophilia were excluded. He underwent successful coil embolisation of the pulmonary artery aneurysms and responded well to immunosuppressive therapy with cyclophosphamide and steroids. Anticoagulation was cautiously continued to limit the long-term risk of secondary thrombosis from his IVC filter. The patient remains well 5 months after initiation of immunosuppressive therapy. Making a diagnosis of Behçet's disease in the setting of thrombosis is crucial, as treatment must include immunosuppression, and, thus, fundamentally differs from the management of most other thrombotic disorders.

ObjectivesThe endoplasmic reticulum aminopeptidase (ERAP1) haplotype Hap10 encodes for a variant allotype of the endoplasmic reticulum (ER)-resident peptide-trimming aminopeptidase ERAP1 with low enzymatic activity. This haplotype recessively confers the highest risk for Behçet’s diseases (BD) currently known, but only in carriers of HLA-B*51, the classical risk factor for the disease. The mechanistic implications and biological consequences of this epistatic relationship are unknown. Here, we aimed to determine its biological relevance and functional impact.MethodsWe genotyped and immune phenotyped a cohort of 26 untreated Turkish BD subjects and 22 healthy donors, generated CRISPR-Cas9 ERAP1 KOs from HLA-B*51+ LCL, analysed the HLA class I-bound peptidome for peptide length differences and assessed immunogenicity of genome-edited cells in CD8 T cell co-culture systems.ResultsAllele frequencies of ERAP1-Hap10 were similar to previous studies. There were frequency shifts between antigen-experienced and naïve CD8 T cell populations of carriers and non-carriers of ERAP1-Hap10 in an HLA-B*51 background. ERAP1 KO cells showed peptidomes with longer peptides above 9mer and significant differences in their ability to stimulate alloreactive CD8 T cells compared with wild-type control cells.ConclusionsWe demonstrate that hypoactive ERAP1 changes immunogenicity to CD8 T cells, mediated by an HLA class I peptidome with undertrimmed peptides. Naïve/effector CD8 T cell shifts in affected carriers provide evidence of the biological relevance of ERAP1-Hap10/HLA-B*51 at the cellular level and point to an HLA-B51-restricted process. Our findings suggest that variant ERAP1-Hap10 partakes in BD pathogenesis by generating HLA-B51-restricted peptides, causing a change in immunodominance of the ensuing CD8 T cell response.

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Headaches are a common, but under-recognized and understudied symptom in the context of the rheumatic diseases. They can result from intracranial pathology, such as parenchymal and meningeal inflammation, thrombosis, space-occupying lesions, and more. Inflammation, irritation, or degeneration of anatomically related structures such as the eyes, neck, and sinuses can equally cause headaches. In addition, patients with rheumatologic disorders have the same tendencies as the general population to develop primary headaches. While the latter are benign in nature, and generally require only symptomatic relief, the former type of headaches may signal disease manifestation, progression, or complication. Thus, familiarity with common and uncommon headache syndromes related to rheumatologic disorders as well as with their possible underlying disease processes and mechanisms is important. This will help to successfully develop an effective approach toward the evaluation of patients presenting with headaches in a rheumatologic context, and, ultimately, diagnose and treat potentially severe underlying disease.

Normal lung development critically depends on HH (Hedgehog) and PDGF (platelet-derived growth factor) signaling, which coordinate mesenchymal differentiation and proliferation. PDGF signaling is required for postnatal alveolar septum formation by myofibroblasts. Recently, we demonstrated a requirement for HH in postnatal lung development involving alveolar myofibroblast differentiation. Given shared features of HH signaling and PDGF signaling and their impact on this key cell type, we sought to clarify their relationship during murine postnatal lung development. Timed experiments revealed that HH inhibition phenocopies the key lung myofibroblast phenotypes of Pdgfa (platelet-derived growth factor subunit A) and Pdgfra (platelet-derived growth factor receptor alpha) knockouts during secondary alveolar septation. Using a dual signaling reporter, Gli1 lZ ;Pdgfra EGFP , we show that HH and PDGF pathway intermediates are concurrently expressed during alveolar septal myofibroblast accumulation, suggesting pathway convergence in the generation of lung myofibroblasts. Consistent with this hypothesis, HH inhibition reduces Pdgfra expression and diminishes the number of Pdgfra-positive and Pdgfra -lineage cells in postnatal lungs. Bulk RNA sequencing data of Pdgfra-expressing cells from Postnatal Day 8 (P8) lungs show that HH inhibition alters the expression not only of well-established HH targets but also of several putative PDGF target genes. This, together with the presence of Gli-binding sites in PDGF target genes, suggests HH input into PDGF signaling. We identified these HH/PDGF targets in several postnatal lung mesenchymal cell populations, including myofibroblasts, using single-cell transcriptomic analysis. Collectively, our data indicate that HH signaling and PDGF signaling intersect to support myofibroblast/fibroblast function during secondary alveolar septum formation. Moreover, they provide a molecular foundation relevant to perinatal lung diseases associated with impaired alveolarization.