The role of EXT and growth signalling pathways in osteochondroma and its progression towards secondary peripheral chondrosarcoma

Osteochondroma is a cartilage capped benign bone tumour, arising at the external surface of bones preformed by endochondral ossification. A small percentage of osteochondromas can progress towards its malignant counterpart, secondary peripheral chondrosarcoma. About 15% of osteochondromas occur in the context of a rare hereditary syndrome, Multiple Osteochondromas for which two genes have been identified as causative genes, namely EXT1 and EXT2, which have been identified as tumor suppressor genes. However the vast majority of osteochondromas present as solitary lesions. We were able to demonstrate that similar to hereditary osteochondromas EXT1 also acts as a classical tumour suppressor gene in solitary osteochondroma. The EXT genes function as a complex in the biosynthesis of heparin sulphate proteoglycans (HSPGs), large multifunctional macromolecules that are involved in several growth signaling pathways. We showed that the loss of EXT1 and in hereditary cases also EXT2 is accompanied by intracellular accumulation of HSPGs, suggesting a disrupted EXT1/2 complex. The growth signalling pathways known from normal longitudinal bone growth are affected differently in osteochondromas and chondrosarcomas. The IHH signaling functions autonomously in osteochondromas and its activity decreases during malignant transformation and progression of chondrosarcomas, whereas the PTHLH and TFG-_ signaling cascades seem to be re-activated.UBL - phd migration 201

A Space Odyssey: Experimental Manipulation of Threat Perception and Anxiety-Related Interpretation Bias in Children

This study provides a first test of an experimental method, the “space odyssey” paradigm, that was designed to manipulate interpretation bias in children. Seventy non-clinical children aged 8–12 years first completed a standardized anxiety questionnaire. Following this, they completed the space odyssey paradigm to induce either a negative or a positive interpretation bias. After this stage of interpretation training, children were presented with a series of ambiguous vignettes for which they had to rate perceived levels of threat as an index of interpretation bias. Results indicated that the space odyssey paradigm was successful in training interpretations: children in the negative training condition quickly learned to choose negative outcomes, while children in the positive training condition rapidly learned to select positive outcomes. Most importantly, children’s subsequent threat perception scores for the ambiguous vignettes were affected by the manipulation. That is, children in the negative training condition perceived more threat than children in the positive training condition. Interestingly, the effects of training were most pronounced in high anxious children. Directions for future research with this paradigm are briefly discussed

Multiple Osteochondromas: Clinicopathological and Genetic Spectrum and Suggestions for Clinical Management

Multiple Osteochondromas is an autosomal dominant disorder characterised by the presence of multiple osteochondromas and a variety of orthopaedic deformities. Two genes causative of Multiple Osteochondromas, Exostosin-1 (EXT1) and Exostosin-2 (EXT2), have been identified, which act as tumour suppressor genes. Osteochondroma can progress towards its malignant counterpart, secondary peripheral chondrosarcoma and therefore adequate follow-up of Multiple Osteochondroma patients is important in order to detect malignant transformation early

Spondyloarthritis mass cytometry immuno-monitoring: a proof of concept study in the tight-control and treat-to target TiCoSpA trial

Objective: Mass cytometry (MC) immunoprofiling allows high-parameter phenotyping of immune cells. We set to investigate the potential of MC immuno-monitoring of axial spondyloarthritis (axSpA) patients enrolled in the Tight Control SpondyloArthritis (TiCoSpA) trial. Methods: Fresh, longitudinal PBMCs samples (baseline, 24, and 48 weeks) from 9 early, untreated axSpA patients and 7 HLA-B27+ controls were analyzed using a 35-marker panel. Data were subjected to HSNE dimension reduction and Gaussian mean shift clustering (Cytosplore), followed by Cytofast analysis. Linear discriminant analyzer (LDA), based on initial HSNE clustering, was applied onto week 24 and 48 samples. Results: Unsupervised analysis yielded a clear separation of baseline patients and controls including a significant difference in 9 T cell, B cell, and monocyte clusters (cl), indicating disrupted immune homeostasis. Decrease in disease activity (ASDAS score; median 1.7, range 0.6-3.2) from baseline to week 48 matched significant changes over time in five clusters: cl10 CD4 Tnai cells median 4.7 to 0.02%, cl37 CD4 T-em cells median 0.13 to 8.28%, cl8 CD4 Tcm cells median 3.2 to 0.02%, cl39 B cells median 0.12 to 2.56%, and cl5 CD38+ B cells median 2.52 to 0.64% (all pPathophysiology and treatment of rheumatic disease

Immunoprofiling of early, untreated rheumatoid arthritis using mass cytometry reveals an activated basophil subset inversely linked to ACPA status

Background Autoantibody production is a hallmark of rheumatoid arthritis (RA). Anti-citrullinated protein antibodies (ACPA) are highly disease-specific, and their presence is associated with more severe disease and poor prognosis compared to ACPA-negative patients. However, the immune cell composition associated with antibody-positive/negative disease is incompletely defined. Mass cytometry (MC) is a high-dimensional technique offering new possibilities in the determination of the immune cell composition in rheumatic diseases. Here, we set up a broad phenotyping panel to study the immune cell profile of early untreated RA to investigate if specific immune cell subsets are associated with ACPA+ versus ACPA- RA. Methods Freshly obtained PBMCs of early, untreated RA patients (8 ACPA+ and 7 ACPA-) were analysed using a 36-marker MC panel, including markers related to various immune lineages. Data were processed using Cytosplore for dimensional reduction (HSNE) and clustering. Groups were compared using Cytofast. A second validation cohort of cryopreserved PBMCs obtained from early RA patients (27 ACPA+ and 20 ACPA-) was used to confirm MC data by flow cytometry (FC). FC data were processed and analysed using both an unsupervised analysis pipeline and through manual gating. Results MC indicated no differences when comparing major immune lineages (i.e. monocytes, T and B cells), but highlighted two innate subsets: CD62L(+) basophils (p = 0.33) and a subset of CD16(-) NK cells (p = 0.063). Although the NK cell subset did not replicate by FC, FC replication confirmed the difference in CD62L(+) basophil frequency when comparing ACPA+ to ACPA- patients (mean 0.32% vs. 0.13%; p = 0.01). Conclusions Although no differences in major lineages were found between early ACPA+ and ACPA- RA, this study identified the reduced presence of activated basophils in ACPA-negative disease as compared to ACPA-positive disease and thereby provides the first evidence for a connection between activated basophils and ACPA status.Pathophysiology and treatment of rheumatic disease

The Genomic Landscape of Actinic Keratosis

Actinic keratoses (AK) are lesions of epidermal keratinocyte dysplasia and are precursors for invasive cutaneous squamous cell carcinoma (CSCC). Identifying the specific genomic alterations driving progression from normal skin-AK-invasive CSCC is challenging due to the massive ultraviolet radiation-induced mutational burden characteristic at all stages of this progression. Here, we report the largest AK whole exome sequencing study to date and perform mutational signature and candidate driver gene analysis on these lesions. We demonstrate in 37 AK, from both immunosuppressed and immunocompetent patients, that there are significant similarities to CSCC in terms of mutational burden, copy number alterations, mutational signatures and patterns of driver gene mutations. We identify 44 significantly mutated AK driver genes and confirm that these genes are similarly altered in CSCC. We identify the azathioprine mutational signature in all AK from patients exposed to the drug, providing further evidence for its role in keratinocyte carcinogenesis. CSCC differ from AK in having higher levels of intra-sample heterogeneity. Alterations in signaling pathways also differ, with immune-related signaling and TGF-β signaling significantly more mutated in CSCC. Integrating our findings with independent gene expression datasets confirms that dysregulated TGF-β signaling may represent an important event in AK-CSCC progression