Hsu-Wen Tseng

Interleukin-23 Mediates the Intestinal Response to Microbial β-1,3-Glucan and the Development of Spondyloarthritis Pathology in SKG Mice

Spondyloarthritides (SpA) occur in 1% of the population and include ankylosing spondylitis (AS) and arthropathy of inflammatory bowel disease (IBD), with characteristic spondylitis, arthritis, enthesitis, and IBD. Genetic studies implicate interleukin‐23 (IL‐23) receptor signaling in the development of SpA and IBD, and IL‐23 overexpression in mice is sufficient for enthesitis, driven by entheseal‐resident T cells. However, in genetically prone individuals, it is not clear where IL‐23 is produced and how it drives the SpA syndrome, including IBD or subclinical gut inflammation of AS. Moreover, it is unclear why specific tissue involvement varies between patients with SpA. We undertook this study to determine the location of IL‐23 production and its role in SpA pathogenesis in BALB/c ZAP‐70W163C–mutant (SKG) mice injected intraperitoneally with β‐1,3‐glucan (curdlan).

Excessive bone formation in a mouse model of ankylosing spondylitis is associated with decreases in Wnt pathway inhibitors.

IntroductionAnkylosing spondylitis (AS) is unique in its pathology where inflammation commences at the entheses before progressing to an osteoproliferative phenotype generating excessive bone formation that can result in joint fusion. The underlying mechanisms of this progression are poorly understood. Recent work has suggested that changes in Wnt signalling, a key bone regulatory pathway, may contribute to joint ankylosis in AS. Using the proteoglycan-induced spondylitis (PGISp) mouse model which displays spondylitis and eventual joint fusion following an initial inflammatory stimulus, we have characterised the structural and molecular changes that underlie disease progression.MethodsPGISp mice were characterised 12 weeks after initiation of inflammation using histology, immunohistochemistry (IHC) and expression profiling.ResultsInflammation initiated at the periphery of the intervertebral discs progressing to disc destruction followed by massively excessive cartilage and bone matrix formation, as demonstrated by toluidine blue staining and IHC for collagen type I and osteocalcin, leading to syndesmophyte formation. Expression levels of DKK1 and SOST, Wnt signalling inhibitors highly expressed in joints, were reduced by 49% and 63% respectively in the spine PGISp compared with control mice (P < 0.05) with SOST inhibition confirmed by IHC. Microarray profiling showed genes involved in inflammation and immune-regulation were altered. Further, a number of genes specifically involved in bone regulation including other members of the Wnt pathway were also dysregulated.ConclusionsThis study implicates the Wnt pathway as a likely mediator of the mechanism by which inflammation induces bony ankylosis in spondyloarthritis, raising the potential that therapies targeting this pathway may be effective in preventing this process.

CD169(+) macrophages mediate pathological formation of woven bone in skeletal lesions of prostate cancer.

Skeletal metastases present a major clinical challenge for prostate cancer patient care, inflicting distinctive mixed osteoblastic and osteolytic lesions that cause morbidity and refractory skeletal complications. Macrophages are abundant in bone and bone marrow and can influence both osteoblast and osteoclast function in physiology and pathology. Herein, we examined the role of macrophages in prostate cancer bone lesions, particularly the osteoblastic response. First, macrophage and lymphocyte distributions were qualitatively assessed in patients prostate cancer skeletal lesions by immunohistochemistry. Second, macrophage functional contributions to prostate tumour growth in bone were explored using an immune‐competent mouse model combined with two independent approaches to achieve in vivo macrophage depletion: liposome encapsulated clodronate that depletes phagocytic cells (including macrophages and osteoclasts); and targeted depletion of CD169+ macrophages using a suicide gene knock‐in model. Immunohistochemistry and histomorphometric analysis were performed to quantitatively assess cancer‐induced bone changes. In human bone metastasis specimens, CD68+ macrophages were consistently located within the tumour mass. Osteal macrophages (osteomacs) were associated with pathological woven bone within the metastatic lesions. In contrast, lymphocytes were inconsistently present in prostate cancer skeletal lesions and when detected, had varied distributions. In the immune‐competent mouse model, CD169+ macrophage ablation significantly inhibited prostate cancer‐induced woven bone formation, suggesting that CD169+ macrophages within pathological woven bone are integral to tumour‐induced bone formation. In contrast, pan‐phagocytic cell, but not targeted CD169+ macrophage depletion resulted in increased tumour mass, indicating that CD169− macrophage subset(s) and/or osteoclasts influenced tumour growth. In summary, these observations indicate a prominent role for macrophages in prostate cancer bone metastasis that may be therapeutically targetable to reduce the negative skeletal impacts of this malignancy, including tumour‐induced bone modelling. Copyright

Inflammation-driven bone formation in a mouse model of ankylosing spondylitis: sequential not parallel processes

BackgroundAnkylosing spondylitis (AS) is an immune-mediated arthritis particularly targeting the spine and pelvis and is characterised by inflammation, osteoproliferation and frequently ankylosis. Current treatments that predominately target inflammatory pathways have disappointing efficacy in slowing disease progression. Thus, a better understanding of the causal association and pathological progression from inflammation to bone formation, particularly whether inflammation directly initiates osteoproliferation, is required.MethodsThe proteoglycan-induced spondylitis (PGISp) mouse model of AS was used to histopathologically map the progressive axial disease events, assess molecular changes during disease progression and define disease progression using unbiased clustering of semi-quantitative histology. PGISp mice were followed over a 24-week time course. Spinal disease was assessed using a novel semi-quantitative histological scoring system that independently evaluated the breadth of pathological features associated with PGISp axial disease, including inflammation, joint destruction and excessive tissue formation (osteoproliferation). Matrix components were identified using immunohistochemistry.ResultsDisease initiated with inflammation at the periphery of the intervertebral disc (IVD) adjacent to the longitudinal ligament, reminiscent of enthesitis, and was associated with upregulated tumor necrosis factor and metalloproteinases. After a lag phase, established inflammation was temporospatially associated with destruction of IVDs, cartilage and bone. At later time points, advanced disease was characterised by substantially reduced inflammation, excessive tissue formation and ectopic chondrocyte expansion. These distinct features differentiated affected mice into early, intermediate and advanced disease stages. Excessive tissue formation was observed in vertebral joints only if the IVD was destroyed as a consequence of the early inflammation. Ectopic excessive tissue was predominantly chondroidal with chondrocyte-like cells embedded within collagen type II- and X-rich matrix. This corresponded with upregulation of mRNA for cartilage markers Col2a1, sox9 and Comp. Osteophytes, though infrequent, were more prevalent in later disease.ConclusionsThe inflammation-driven IVD destruction was shown to be a prerequisite for axial disease progression to osteoproliferation in the PGISp mouse. Osteoproliferation led to vertebral body deformity and fusion but was never seen concurrent with persistent inflammation, suggesting a sequential process. The findings support that early intervention with anti-inflammatory therapies will be needed to limit destructive processes and consequently prevent progression of AS.

CD169+ macrophages are critical for osteoblast maintenance and promote intramembranous and endochondral ossification during bone repair

Osteal macrophages (osteomacs) contribute to bone homeostasis and regeneration. To further distinguish their functions from osteoclasts, which share many markers and growth factor requirements, we developed a rapid, enzyme-free osteomac enrichment protocol that permitted characterization of minimally manipulated osteomacs by flow cytometry. Osteomacs differ from osteoclasts in expression of Siglec1 (CD169). This distinction was confirmed using the CD169-diphtheria toxin (DT) receptor (DTR) knock-in model. DT treatment of naïve CD169-DTR mice resulted in selective and striking loss of osteomacs, whilst osteoclasts and trabecular bone area were unaffected. Consistent with a previously-reported trophic interaction, osteomac loss was accompanied by a concomitant and proportionately striking reduction in osteoblasts. The impact of CD169+ macrophage depletion was assessed in two models of bone injury that heal via either intramembranous (tibial injury) or endochondral (internally-plated femoral fracture model) ossification. In both models, CD169+ macrophage, including osteomac depletion compromised bone repair. Importantly, DT treatment in CD169-DTR mice did not affect osteoclast frequency in either model. In the femoral fracture model, the magnitude of callus formation correlated with the number of F4/80+ macrophages that persisted within the callus. Overall these observations provide compelling support that CD169+ osteomacs, independent of osteoclasts, provide vital pro-anabolic support to osteoblasts during both bone homeostasis and repair.

Macrophage-derived oncostatin M contributes to human and mouse neurogenic heterotopic ossifications

Neurogenic heterotopic ossification (NHO) is the formation of ectopic bone generally in muscles surrounding joints following spinal cord or brain injury. We investigated the mechanisms of NHO formation in 64 patients and a mouse model of spinal cord injury-induced NHO. We show that marrow from human NHOs contains hematopoietic stem cell (HSC) niches, in which mesenchymal stromal cells (MSCs) and endothelial cells provide an environment supporting HSC maintenance, proliferation, and differentiation. The transcriptomic signature of MSCs from NHOs shows a neuronal imprinting associated with a molecular network required for HSC support. We demonstrate that oncostatin M (OSM) produced by activated macrophages promotes osteoblastic differentiation and mineralization of human muscle-derived stromal cells surrounding NHOs. The key role of OSM was confirmed using an experimental model of NHO in mice defective for the OSM receptor (OSMR). Our results provide strong evidence that macrophages contribute to NHO formation through the osteogenic action of OSM on muscle cells within an inflammatory context and suggest that OSM/OSMR could be a suitable therapeutic target. Altogether, the evidence of HSCs in ectopic bones growing at the expense of soft tissue in spinal cord/brain-injured patients indicates that inflammation and muscle contribute to HSC regulation by the brain-bone-blood triad.

Macrophages Driving Heterotopic Ossification: Convergence of Genetically-Driven and Trauma-Driven Mechanisms: LETTER TO THE EDITOR

Jean-Pierre Levesque, Natalie A Sims, Allison R Pettit, Kylie A Alexander, Hsu-Wen Tseng, Fr ed eric Torossian, FranS cois Genêt, Jean-Jacques Lataillade, and Marie-Caroline Le Bousse-Kerdil es Mater Research – The University of Queensland, Translational Research Institute, Woolloongabba, Australia The University of Queensland, Faculty of Medicine, Herston, Australia St. Vincent’s Institute of Medical Research, Fitzroy, Australia Department of Medicine, St. Vincent’s Hospital, The University of Melbourne, Fitzroy, Australia INSERM-UMR-S-MD1197, Universit e Paris 11, Hôpital Paul Brousse, Villejuif, France Service de M edecine Physique et de R eadaptation, Hôpital Raymond Poincar e, Garches, France Universit e de de Versailles Saint-Quentin-en-Yvelines, INSERM U1179, Montigny le Bretonneux, France Centre de Transfusion Sanguine des Arm ees, L’Institut de Recherche Biom edicale des Arm ees, Clamart, France

Characterization of Normal Murine Carpal Bone Development Prompts Re-Evaluation of Pathologic Osteolysis as the Cause of Human Carpal-Tarsal Osteolysis Disorders

Multicentric carpal-tarsal osteolysis; multicentric osteolysis, nodulosis, and arthropathy; and Winchester syndromes, skeletal dysplasias characterized by carpal/tarsal and epiphyseal abnormalities, are caused by mutations in v-maf musculoaponeurotic fibrosarcoma oncogene ortholog B (MAFB), matrix metalloproteinase (MMP) 2, and MMP14, respectively; however, the underlying pathophysiology is unclear. Osteoclast-mediated osteolysis has been regarded as the main mechanism, but does not explain the skeletal distribution. We hypothesized that MAFB, MMP-2, and MMP-14 have integral roles in carpal/tarsal and epiphyseal bone development. Normal neonatal mouse forepaws were imaged by micro-computed tomography and examined histologically. Murine forepaw ossification occurred sequentially. Subarticular regions of endochondral ossification showed morphologic and calcification patterns that were distinct from archetypical physeal endochondral ossification. This suggests that two different forms of endochondral ossification occur. The skeletal sites showing the greatest abnormality in the carpal-tarsal osteolysis syndromes are regions of subarticular ossification. Thus, abnormal bone formation in areas of subarticular ossification may explain the site-specific distribution of the carpal-tarsal osteolysis phenotype. MafB, Mmp-2, and Mmp-14 were expressed widely, and tartrate-resistant acid phosphatase staining notably was absent in the subarticular regions of the cartilage anlagen and entheses at a time point most relevant to the human osteolysis syndromes. Thus, abnormal peri-articular skeletal development and modeling, rather than excessive bone resorption, may be the underlying pathophysiology of these skeletal syndromes.

Endochondral Bone Formation and Advanced Enthesitis Are Key Features Of Proteoglycan Induced Spondylitis Mouse Model Of Ankylosing Spondylitis

SUPPLEMENTSex Bias In Autoimmune Diseases : Increased Risk Of 47,XXX In Systemic Lupus Erythematosus (SLE) and Sjogrens Syndrome (SS) Supports The Gene Dose HypothesisBackground/Purpose: Human FoxP3+ Th-cells are heterogeneous in function and include not only suppressive cells (TRegs) but also nonsuppressive cells that abundantly secrete proinflammatory cytokines. We have previously shown that FoxP3+ Th-cells were increased in GPA-patients during remission as compared to healthy controls (HCs). In this group of patients, however, we observed a defective suppressor function of TRegs, and an increase in the percentage of Th-17 cells. These observations make it tempting to investigate whether increased FoxP3+ Th-cells in GPA-patients are attributed to an increase in the cytokine-secreting non-suppressive FoxP3+Th-cells. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 46 GPA-patients in remission and from 22 age- and sex-matched HCs. Expression of CD4, CD45RO, and FoxP3 were determined by flow cytometric analysis. The expression levels of FoxP3 and CD45RO were used for distinction between activated suppressor TRegs (FoxP3HighCD45RO+; ASTReg), resting suppressor TRegs (FoxP3LowCD45RO-; RSTReg), and cytokine-secreting non-suppressor TRegs (FoxP3LowCD45RO+; NONTReg) cells. Intracellular expression of IFNg, IL-17, and IL-21 were determined in the various FoxP3+ Th-cell subsets after in vitro activation of PBMCs by PMA and Ca-Ionophore. Results: A significant increase in the frequency of NONTReg cells was observed in GPA-patients as compared with HCs, whereas no differences were detected in RSTReg- and ASTReg cells between GPA-patients and HCs. The distribution of RSTReg- and NONTReg cells did not differ between ANCA-negative and ANCA-positive patients, whereas lower percentages of ASTReg cells were observed in ANCA-positive patients as compared to ANCA-negative patients and HCs. Importantly, a significant increase in the percentage of IL-17+ and IL-21+ cells was seen within the NONTRegcells from ANCA-positive patients (n= 9) when compared to ANCA-negative (n= 10) and HCs (n= 12), whereas no differences were found between ANCA-negative and HCs. Conclusion: Increased FoxP3 expression in Th-cells from GPA-patients is related to an increase in a subset of non-suppressive Th-cells. Increased production of IL-17 and IL-21 cytokines, in NONTReg cells from ANCApositive patients points towards FoxP3+ effector cells and decrease in suppressive TReg cells in relation to ANCA production.Complex Functional Effects Within The HLA Contribute To Sjogrens Syndrome Pathogenesis and May Influence Both Transcriptional Regulation and Peptide Binding