H. J. Girschick

Intracellular persistence ofBorrelia burgdorferi in human synovial cells

To investigate ifBorrelia burgdorferi can persist in resident joint cells, an infection model using cell cultures of human synovial cells was established and compared to the interaction ofBorrelia burgdorferi and human macrophages.Borrelia burgdorferi were found attached to the cell surface or folded into the cell membrane of synovial cells analysed by transmission electron and confocal laser scanning microscopy. In contrast to macrophages, morphologically intactBorrelia burgdorferi were found in the cytosol of synovial cells without engulfment by cell membrane folds or phagosomes.Borrelia burgdorferi were isolated from parallel cultures. Treatment with ceftriaxone eradicated extracellularBorrelia burgdorferi, but spirochetes were reisolated after lysis of the synovial cells.Borrelia burgdorferi persisted inside synovial cells for at least 8 weeks. These data suggested thatBorrelia burgdorferi might be able to persist within resident joint cells in vivo.

Association of the autoimmunity locus 4q27 with juvenile idiopathic arthritis

OBJECTIVEnJuvenile idiopathic arthritis (JIA) is characterized by chronic arthritis and an autoimmune etiology. In several autoimmune diseases, including rheumatoid arthritis (RA), an association with the 4q27 locus has been reported. We undertook this study to investigate the possible role of the 4q27 locus in JIA.nnnMETHODSnA case-control association study was conducted, with a total of 655 Caucasian JIA patients and 791 healthy controls divided into 2 independent sample sets. The rs6822844 marker in the 4q27 locus was genotyped.nnnRESULTSnIn the first and larger sample set, a 5% decrease in T allele frequency was observed in patients compared with controls (allelic odds ratio [OR] 0.72 [95% confidence interval 0.55-0.95], P = 0.019), and in the second set, a 3% decrease was observed (allelic OR 0.81 [95% confidence interval 0.61-1.09], P = 0.169). The combined data set generated an OR of 0.76 (95% confidence interval 0.62-0.93, P = 7.08 x 10(-3)). When the different JIA subtypes were analyzed individually, significant decreases were seen in the subtypes with a polyarticular course of disease (extended oligoarthritis [P = 0.019] and rheumatoid factor-negative polyarthritis [P = 0.038]).nnnCONCLUSIONnOur findings suggest that the 4q27 locus, previously reported to be associated with RA, type 1 diabetes mellitus, celiac disease, and psoriatic arthritis, is also associated with susceptibility to JIA.

Altered expression of IL-10 family cytokines in monocytes from CRMO patients result in enhanced IL-1β expression and release

Chronic recurrent multifocal osteomyelitis (CRMO) is characterized by reduced activation of protein kinases ERK1 and 2 in monocytes resulting in impaired IL-10 expression. IL10 and its homologs IL19 and IL20 are organized in the IL10 cluster on chromosome 1q32. IL-10 and IL-19 are immune-regulatory cytokines, while IL-20 acts in a pro-inflammatory manner. The NLRP3 inflammasome, a multi-protein complex forming in response to innate stimuli, mediates IL-1β cleavage and release. Here, we investigated IL-10-related cytokine expression in CRMO monocytes, underlying molecular events, and effects on inflammatory responses. We observed reduced anti-inflammatory IL-10 and IL-19 expression, and enhanced IL-20 expression in CRMO monocytes. Reduced IL-10 and IL-19 expression was associated with impaired Sp-1 recruitment to regulatory regions, contributing to NLRP3 inflammasome activation, which may induce inflammatory bone-loss. Our findings underscore the importance of balanced receptor-, cell-, and tissue-specific cytokine expression for immune homeostasis, providing additional arguments for cytokine blocking strategies in CRMO.

Crohn?s disease during etanercept therapy in juvenile idiopathic arthritis: a case report and review of the literature

Tumor necrosis factor alpha (TNFα) has broad effects on the immune system including lymphoid organ development as well as growth, survival und function of immune cells. TNFα has two main functions: regulatory effects and proinflammatory activities. In several diseases such as juvenile and adult “rheumatoid” arthritis, psoriasis and chronic inflammatory bowel disease, the application of TNFα-blocking medications has been beneficial. However, induction of inflammation in several organs including the eye, CNS, skin and gastrointestinal tract has been reported. We report on an 11-year-old girl with juvenile idiopathic arthritis, who developed Crohn’s disease (CD) while taking etanercept for her arthritis. Etanercept was discontinued and an antibody-based anti-TNF treatment using adalimumab was started, which induced remission of the gastrointestinal symptoms promptly. This case indicates that immunodysregulatory and even proinflammatory effects of etanercept are of relevance in the clinical practice. Furthermore, TNFα as a part of its function seems to downregulate mucosal inflammation in CD.

Clinical course and prognostic value of disease activity in the first two years in different subtypes of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is a heterogeneous disease involving chronic arthritis. The clinical course is characterized by a fluctuating pattern of active and inactive disease. We have described in detail the clinical course in different JIA subtypes during the first 2 years after diagnosis and studied its relationship to disease activity in the following years.

Seronegative Lyme arthritis.

We present a 10-year-old girl who had been diagnosed with juvenile idiopathic arthritis 5xa0years before and who experienced a flare of arthritis affecting one knee while she was off medication for almost 3xa0years. Seronegative Lyme arthritis had to be diagnosed based on the detection of Borrelia burgdorferi DNA in synovial fluid. No humoral immune response to Borrelia burgdorferi was detectable before, at the time of diagnosis and up to 3xa0years later.

Chronic Nonbacterial Osteomyelitis: Pathophysiological Concepts and Current Treatment Strategies.

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disorder, covering a clinical spectrum with asymptomatic inflammation of single bones at the one end, and chronic recurrent multifocal osteomyelitis (CRMO) at the other end. The exact molecular pathophysiology of CNO remains largely unknown. Provided familial clusters and the association with inflammatory disorders of the skin and intestine suggest a genetic predisposition. Recently, profound dysregulation of cytokine responses was demonstrated in CRMO. Failure to produce antiinflammatory cytokines interleukin (IL)-10 and IL-19 contributes to activation of inflammasomes and subsequent IL-1β release. In IL-10–deficient and in CNO-prone chronic multifocal osteomyelitis mice, IL-1β was linked to bone inflammation. Further, alterations to the gut microbiome were suggested in contributing to IL-1β release from innate immune cells in mice, offering an interesting target in the search for molecular mechanisms in CNO. Here, we summarize clinical presentation and treatment options in CNO/CRMO, current pathophysiological concepts, available mouse models, and promising future scientific directions.

Serum biomarkers for the diagnosis and monitoring of chronic recurrent multifocal osteomyelitis (CRMO).

Chronic recurrent multifocal osteomyelitis (CRMO), the most severe form of chronic nonbacterial osteomyelitis, is an autoinflammatory bone disorder. A timely diagnosis and treatment initiation is complicated by the absence of widely accepted diagnostic criteria and an incomplete pathophysiological understanding. The aim of this study was to determine biomarkers for the diagnosis and follow-up of CRMO. Serum of 56 CRMO patients was collected at the time of diagnosis. As controls, sera from treatment-naïve age-matched patients with Crohn’s disease (Nxa0=xa062) or JIA (Nxa0=xa028) as well as healthy individuals (Nxa0=xa062) were collected. Multiplex analysis of 25 inflammation markers was performed. Statistical analysis was performed using Kruskal–Wallis and Mann–Whitney U tests, canonical discriminant analysis, and mixed model variance analysis. Mostly monocyte-derived serum proteins were detectable and differed significantly between groups: IL-1RA, IL-2R, IL-6, IL-12, eotaxin, MCP-1, MIP-1b, RANTES. Multicomponent discriminant analysis allowed for the definition of algorithms differentiating between CRMO, Crohn’s disease, and healthy controls. Persistently high levels of MCP-1, IL-12, sIL-2R correlated with incomplete remission in follow-up samples from CRMO patients. Discrimination algorithms allow differentiation between patients with CRMO or Crohn’s disease, and healthy individuals. IL-12, MCP-1, and sIL-2R can act as markers for treatment response. Though confirmation of our findings in larger multiethnical cohorts is warranted, they may prove valuable to differentiate between otherwise healthy individuals or Crohn’s disease patients with “bone pain” and CRMO patients. The elevation of mainly monocyte-derived pro-inflammatory serum proteins supports the hypothesis of pro-inflammatory monocyte/macrophages driving inflammation in CRMO.

Borrelia burgdorferi Downregulates ICAM-1 on Human Synovial Cells In Vitro

Lyme arthritis following infection with Borrelia burgdorferi (B. burgdorferi) is associated with the presence of bacteria in the joint, but the mechanism of persistent infection in the presence of specific antibodies and lymphocytes remains unknown. To investigate how an infection with B. burgdorferi might influence the local immune response in the joint, we examined the expression of cell adhesion molecules, human leucocyte antigens and inducible nitric oxide synthase (iNOS)-1 and -2 in human synovial cells after infection with B. burgdorferi in vitro. Synovial cells are known to influence the function of local immunologic effector cells and play a key role in the pannus formation of erosive arthritis. It has been shown previously that B. burgdorferi can persist in the cytosol of human synovial cells. The expression of the surface molecules ICAM-1, VCAM-1, HLA-class-I and -class-II and the cytosolic production of iNOS-1 and -2 in synovial cells was measured by flow cytometry for up to 5 days after infection with B. burgdorferi. A significant, lasting downregulation of surface ICAM-1 could be demonstrated on synovial cells, whereas no significant changes were seen in the expression of VCAM-1, HLA-class-I and -II, and of iNOS-1 and -2. To determine the biological significance of this downregulation an in vitro adhesion assay using peripheral blood mononuclear cells was developed. After infection with B. burgdorferi a significantly smaller number of mononuclear cells was adhering to the synovial cell monolayer. Adhesion of peripheral mononuclear cells was shown to be in part mediated by ICAM-1 by using a blocking mononuclear antibody against ICAM-1. Downregulation of ICAM-1 on synovial cells due to infection with B. burgdorferi might suppress the local immunosurveillance and might help the bacteria to persist in joint cells in vivo.

Infection of an urachal cyst during etanercept therapy in juvenile idiopathic arthritis.

Etanercept, a tumor necrosis factor (TNF) receptor alpha antagonist is licensed for the treatment in patients affected by polyarticular juvenile idiopathic arthritis, who do not tolerate or had an inadequate response to methotrexate. Infections related to immunosuppression by etanercept are of major concern. We report on a 17-year-old boy with enthesitis-related arthritis who developed a major infection of an urachal cyst 18xa0months after initiation of etanercept therapy, which required surgery. The urachus had not been symptomatic before.