Hedgehog and Platelet-derived Growth Factor Signaling Intersect during Postnatal Lung Development.

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, Gli1lZ;PdgfraEGFP, 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.

Immunopathogenesis of Behçet's disease.

Behçet's disease (BD) is a multi-system inflammatory disorder with vasculitic features. It does not suit any of the current pathogenesis-driven disease classifications well, a unifying concept of its pathogenesis is not unanimously conceivable at present, and its etiology is obscure. Still, evidence from immunogenetic and other studies supports the notion of a complex-polygenic disease with robust innate effector responses, reconstitution of regulatory T cells upon successful treatment, and first clues to the role of an, as of yet, underexplored adaptive immune system and its antigen recognition receptors. Without an attempt to be comprehensive, this review aims to collect and organize impactful parts of this evidence in a way that allows the reader to appreciate the work done and define the efforts needed now. The focus is on literature and notions that drove the field into new directions, whether recent or more remote.

Inflammatory eye disease for rheumatologists.

PURPOSE OF REVIEW: This review provides a framework for understanding inflammatory eye disease diagnosis, differential diagnosis, and management for rheumatologists. Uveitis, scleritis, episcleritis, peripheral ulcerative keratitis, and orbital inflammation are all discussed. The goal is to facilitate the development of approaches to inflammatory eye diseases that will help rheumatologists co-manage these patients with eye care providers specializing in ocular inflammation. RECENT FINDINGS: In recent years, studies have aimed to advance biologic treatments and define standard-of-care therapy. Inflammatory eye diseases are highly heterogeneous and often rare, which poses significant challenges to their research and the interpretation of existing data. To date, glucocorticoids, mycophenolate, methotrexate, and TNF inhibitors remain the mainstay of treatment options for many of these diseases. SUMMARY: Patients with inflammatory eye diseases require multidisciplinary care for best outcomes, frequently including rheumatologists. Understanding the differentials, diagnostics, and treatment are essential to preserving vision in these patients. The diverse nature of the disease processes within this field requires focusing on specific disease phenotypes and endotypes in research and clinical practice.

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.

Behçet's disease risk-variant HLA-B51/ERAP1-Hap10 alters human CD8 T cell immunity.

OBJECTIVES: The 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. METHODS: We 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. RESULTS: Allele 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. CONCLUSIONS: We 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.

Modulation of human Th17 cell responses through complement receptor 3 (CD11 b/CD18) ligation on monocyte-derived dendritic cells.

OBJECTIVE: Apoptotic cell receptors contribute to the induction of tolerance by modulating dendritic cell function following the uptake of apoptotic cells or microparticles. Dendritic cells that have bound or ingested apoptotic cells produce only low amounts of pro-inflammatory cytokines and fail to prime effector T cell responses. Specifically, ligation of the apoptotic cell receptor CR3 (CD11 b/CD18) on human monocyte-derived dendritic cells (moDC) down-modates proinflammatory cytokine secretion, but the consequences for human Th17 cell homeostasis and effector responses remain unknown. Here, we aimed to establish whether CD11b-ligated moDC modulate Th17 cell effector reponses to assess their potential for future use in moDC-based suppressive immunotherapy. METHODS: We generated a bead-based surrogate system to target CD11b on monocyte-derived human dendritic cells and examined the effects of CD11b ligation on Th17-skewing cytokine secretion, priming, expansion and functional plasticity in DC/T cell co-culture systems at the poly- and monoclonal level. RESULTS: We show that Th17 cell expansion within the human memory CD4+ T cell compartment was efficiently constricted by targeting the CD11b receptor on moDC. This tolerogenic capacity was primarily dependent on cytokine skewing. Furthermore, ligation of CD11b on healthy homozygous carriers of the rs11143679 (ITGAM) variant - a strong genetic susceptibility marker for human systemic lupus erythematosus - also down-modulated the secretion of Th17-skewing cytokines. CONCLUSION: 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.

Active systemic lupus erythematosus is associated with decreased blood conventional dendritic cells.

OBJECTIVE: The aim of the study is to determine the frequency and functionality of blood conventional dendritic cells (cDCs) in relation to disease activity in systemic lupus erythematosus. METHODS: Blood cDCs were enumerated for 34 SLE patients, defined as "active" (SLEDAI ≥ 4) or "inactive" (SLEDAI < 4), 26 RA subjects and 8 healthy subjects by FACS. cDC activation was measured by IL-12p40/70 staining following resiquimod stimulation. RESULTS: The frequency of blood cDCs was significantly lower in active compared to inactive patients, however, with comparable cDC functionality. CONCLUSION: cDC frequency in active SLE is decreased with no perturbation in cDC function, possibly due to enhanced turnover and/or tissue-specific migration.

Headaches related to rheumatologic disease.

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.

Major vessel thrombosis in Behçet's disease: the dilemma of anticoagulant therapy - the approach of rheumatologists from different countries.

OBJECTIVES: The best treatment for patients with Behçet's disease (BD) with major vessel thrombosis has not been fully determined. Our objective was to raise this therapeutic dilemma and to call for controlled studies to help establish guidelines to address this problem. METHODS: Three patients with BD and major vessel thrombosis whom we recently encountered are described. Their cases were presented to rheumatologists from Turkey, Israel and the USA. The physicians were asked about the kind of treatment they would give each patient at diagnosis of thrombosis and if they chose to give anticoagulation and for long. RESULTS: Fifty-five Turkish, 33 Israeli and 25 American rheumatologists responded to the questionnaire. More than 87% of the Israeli and American rheumatologists would give anticoagulation at the time of diagnosis for the cases of venous thrombosis compared with only 40-44% of the Turkish physicians. In these cases 56% of the American and 45% of the Israeli rheumatologists would give warfarin for life compared with only 5-18% of the Turkish physicians. Regarding a case with intra-cardiac thrombus, 96% of American, 94% of Israeli, and 60% of Turkish rheumatologists would start anticoagulation at diagnosis while 70%, 39% and 33%, respectively would give this treatment for life. CONCLUSIONS: The therapeutic approach towards thrombosis in Behçet's disease differs significantly among rheumatologists from different countries. The different prevalence of the disease in these countries may explain this difference. A randomised controlled prospective trial is needed in order to determine the exact role of anticoagulant treatment in BD.

The role of uric acid and other crystals in osteoarthritis.

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.

Generation of Human Regulatory T Cell Clones.

Human regulatory T cells (Treg) are notoriously difficult to isolate in high purity given the current methods of Treg enrichment. These methods are based on the identification of Treg through several activation-dependent cellular surface markers with varying expression levels in different physiologic and pathologic conditions. Populations isolated as "Treg" therefore often contain considerable numbers of non-Treg effector cells (i.e., Teff) which hamper the precise phenotypic and functional characterization of these cells, their genomic and proteomic characterization, their reliable enumeration in different states of health and disease, as well as their isolation and expansion for therapeutic purposes. The latter, in particular, remains a major hurdle, as the inadvertent expansion of effector cells homing in Treg-relevant cellular compartments (e.g., CD4+CD25+ T cells) may render Treg-based immunotherapy ineffective, or even harmful. This work presents a method that circumvents the problems associated with population-based isolation and expansion of Treg and shows that the generation of Treg candidate clones with the subsequent selection, culture, and expansion of only carefully vetted, monoclonal cells, enables the generation of an ultrapure Treg cell product that can be kept in culture for many months, enabling downstream investigation of these cells, including for possible therapeutic applications.

ST deviation pattern in acute myocardial infarction is not related to lesion location.

BACKGROUND: In ST-elevation MI (STEMI) the culprit artery is usually occluded, whereas non-STEMI (NSTEMI) it is usually patent. The location of the ruptured plaque may influence MI type. We examine whether the distance from the coronary ostium to the culprit lesion is different in STEMI as compared to NSTEMI. METHODS: We selected patients who presented with an acute MI and underwent coronary angiography during hospitalization. The analysis included 754 patients of whom 514 had STEMI and 240 had NSTEMI. The distance from the coronary ostium to the site of thrombosis was measured. RESULTS: For both STEMI and NSTEMI patients the first 60 mm of the coronary artery contained 75% of the culprit lesions. There were no significant differences in median distances from the vessel ostium to the site of thrombosis as well. CONCLUSIONS: The distance from coronary ostium to culprit lesion is similar in STEMI and NSTEMI. Culprit lesion location does not appear to influence the development of STEMI as opposed to NSTEMI.

Flow Plex-A tool for unbiased comprehensive flow cytometry data analysis.

INTRODUCTION: The information content of multiparametric flow cytometry experiments is routinely underexploited given the paucity of adequate tools for unbiased comprehensive data analysis that can be applied successfully and independently by immunologists without computational training. METHODS: We aimed to develop a tool that allows straightforward access to the entire information content of any given flow cytometry panel for immunologists without special computational expertise. We used a data analysis approach which accounts for all mathematically possible combinations of markers in a given panel, coded the algorithm and applied the method to mined and self-generated data sets. RESULTS: We developed Flow Plex, a straightforward computational tool that allows unrestricted access to the information content of a given flow cytometry panel, enables classification of human samples according to distinct immune phenotypes, such as different forms of autoimmune uveitis, acute myeloid leukemia vs "healthy", "old" vs "young", and facilitates the identification of cell populations with potential biologic relevance to states of disease and health. CONCLUSIONS: We provide a tool that allows immunologists and other flow cytometry users with limited bioinformatics skills to extract comprehensive, unbiased information from flow cytometry data sets.

Relation of spontaneous reperfusion in ST-elevation myocardial infarction to more distal coronary culprit narrowings.

Spontaneous reperfusion (SR) of the infarct-related artery may occur in patients with ST-segment-elevation myocardial infarctions (STEMIs). Limited data are available on the angiographic characteristics of these patients. The objective of this study was to determine if there are differences in the distance of the culprit lesion from the coronary ostium in patients with STEMIs with and without SR. Patients who presented with acute STEMIs<12 hours after pain onset and who underwent coronary angiography were entered into the study. Measurement of the distance from the coronary ostium to the culprit lesion was performed. A total of 469 patients with STEMIs were included in the study, of whom 77 met criteria for SR (significant relief of chest pain associated with >or=50% resolution of ST-segment elevation on follow-up electrocardiography) and 392 did not. A highly significant difference was seen in ostial to culprit lesion distance, with the culprit lesions in the SR group being more distal than those in the non-SR group (45+/-22 vs 39+/-20 mm, p<0.009). In conclusion, the findings of this study demonstrate that the location of the culprit lesion in patients with STEMIs who undergo SR is more distal in the involved artery than in patients with STEMIs who do not undergo SR.

Brainstem astrocytoma as a neuro-Behçet's disease mimic.

A 58-year-old man with a history of recurrent aphthous ulcers since childhood was admitted to the hospital with acute neurological decline characterised by loss of motor dexterity, dysarthria, dysphagia and unsteady gait. MRI brain was significant for symmetrical hyperintense T2 fluid attenuated inversion recovery (FLAIR) in the corticospinal tracts, including parts of the pons and the mesodiencephalic junction. Though initial concern was for neuro-Behçet's disease, brain biopsy ultimately revealed a diagnosis of astrocytoma. This report demonstrates a mimic of neuro-Behçet's disease and the importance of confirming the correct diagnosis prior to initiating therapy.

Myelodysplastic syndrome presenting as a Behçet's-like disease with aortitis.

A 46-year-old Hispanic man presented with fever, genital ulcers, left eye redness and chest pain. Physical examination was notable for a healed oral ulcer and scrotal ulcers, and bilateral superficial thrombophlebitis. He was found to have new-onset pancytopenia. CT of the chest showed pericardial and pleural effusions and rapidly progressing inflammation of the aortic arch and ascending vessels. Although the patient had Behcet's disease (BD)-like symptoms, pancytopenia could not be explained by the diagnosis, prompting a bone marrow biopsy which showed myelodysplastic syndrome. This report highlights the importance of excluding alternate disorders before making a diagnosis of Behcet's disease if atypical, BD-incompatible or incomplete constellations of symptoms and findings are present.

Behcet's disease with major vascular involvement.

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.

Acute hyperglycemia and spontaneous reperfusion in acute myocardial infarction.

BACKGROUND: Spontaneous reperfusion (SR) may occur in patients with ST elevation myocardial infarction (STEMI) prior to reperfusion therapy. Hyperglycemia is common on admission in patients with STEMI and is associated with a worse prognosis. Mechanisms remain unclear but may include impairment of coronary flow. The objective of this study was to examine whether acute hyperglycemia influenced the occurrence of SR in patients with STEMI. METHODS: All patients presenting to our institution with acute STEMI with measurement of glucose levels on presentation were eligible. SR was defined as a combination of significant relief of chest pain associated with an at least 70% resolution of ST segment elevation on follow-up ECG. RESULTS: 465 patients were studied of whom 77 patients met criteria for SR. Average glucose levels were not significantly different between the SR and non-SR groups (10.0+/-5.6 mmol/l versus 10.1+/-5.3; P=NS). When patients were divided into normoglycemic and hyperglycemic groups, there was no significant difference in the percentages of such patients in the SR and non-SR groups. (52% versus 54%; P=NS). CONCLUSIONS: Acute hyperglycemia on admission does not predict the occurrence of SR in a general population of patients with acute MI.