Molecular diagnostics in soft tissue sarcomas and gastrointestinal stromal tumors.

Soft tissue sarcomas are rare malignant heterogenous tumors of mesenchymal origin with over fifty subtypes. The use of hematoxylin and eosin stained sections (and immunohistochemistry) in the morphologic assessment of these tumors has been the bane of clinical diagnosis until recently. The last decade has witnessed considerable progress in the understanding and application of molecular techniques in refining the current understanding of soft tissue sarcomas and gastrointestinal stromal tumors beyond the limits of traditional approaches. Indeed, the identification of reciprocal chromosomal translocations and fusion genes in some subsets of sarcomas with potential implications in the pathogenesis, diagnosis and treatment has been revolutionary. The era of molecular targeted therapy presents a platform that continues to drive biomarker discovery and personalized medicine in soft tissue sarcomas and gastrointestinal stromal tumors. In this review, we highlight how the different molecular techniques have enhanced the diagnosis of these tumors with prognostic and therapeutic implications.

Morphologic Characteristics and Mutational Analysis of Fumarate Hydratase Deficient Kidney and Smooth Muscle Tumors.

OBJECTIVES: Fumarate hydratase (FH)-deficient tumors can occur due to germline or somatic mutations and have distinctive morphologic features. The aims of this study are to refine morphologic criteria and identify mutations in FH-deficient smooth muscle tumors (SMTs). METHODS: The morphology of SMTs and kidney tumors submitted to a national reference laboratory for FH immunohistochemistry (IHC) was reviewed by two gynecologic and two genitourinary pathologists, respectively. Fisher exact test was used for analysis. Fourteen SMTs were sequenced using the Illumina TruSight Oncology 500 Assay. RESULTS: Twenty-two kidney tumors (5 FH deficient) and 51 SMTs (27 FH deficient) were reviewed. FH-deficient kidney tumors exclusively showed cord-like growth, rhabdoid change, and absence of coagulative tumor necrosis and psammoma bodies. FH-deficient SMTs were significantly more likely to have staghorn vessels, eosinophilic cytoplasmic inclusions, schwannoma-like areas, or hereditary leiomyomatosis and renal cell cancer-like nuclei (P < .05 for each). Seven of 14 sequenced SMTs showed mutations of the FH gene and no other driver mutations. CONCLUSIONS: FH-deficient SMTs submitted for FH immunohistochemistry (IHC) showed distinct morphology. Although FH IHC is used for screening of FH-deficient tumors, FH mutations were identified in only 50% of FH-deficient SMTs. This highlights the need for additional exploration of mechanisms of FH protein loss in tumors lacking FH mutations.

Clinicopathologic Features of Breast Carcinoma With 2018 American Society of Clinical Oncology/College of American Pathologists Fluorescence In Situ Hybridization Group 3 (Human Epidermal Growth Factor Receptor 2 Chromosome 17 Centromere Ratio <2.0 and Average Human Epidermal Growth Factor Receptor 2 Copy Number ≥6.0) Breast Cancers.

CONTEXT.­: The American Society of Clinical Oncology/College of American Pathologists 2018 update of the human epidermal growth factor receptor 2 (HER2) testing guideline includes a fluorescence in situ hybridization (FISH) group with a HER2 to chromosome 17 centromere (CEP17) ratio less than 2.0 and HER2 copy number 6.0 or greater (group 3), which requires integrated review of HER2 immunohistochemistry (IHC). OBJECTIVE.­: To assess the clinicopathologic features of group 3 patients and determine features associated with HER2-positive status after workup. DESIGN.­: Cases submitted for HER2 FISH between January 2019 and June 2022 were identified, and relevant clinicopathologic information was obtained. RESULTS.­: One hundred forty-two HER2 FISH cases (1.6%) were group 3. In 52 cases (36.6%) IHC was negative (0/1+), in 3 (2.8%) IHC was positive (3+), and in 86 (60.6%) IHC was 2+. Annotated IHC 2+ slides were recounted by a second reviewer in targeted areas, where 16 of 86 (18.6%) had a HER2:CEP17 ratio less than 2.0 and a HER2 copy number of 4.0 or greater to less than 6.0 (HER2 negative). After combined IHC/FISH review, 74 of 142 (52.1%) were classified as HER2 positive. HER2 copy number/cell was higher in HER2-positive compared with HER2-negative cases after the workup. The extent and intensity of staining in IHC 2+ cases did not correlate with the level of gene amplification. Twenty percent of HER2-positive patients achieved pathologic complete response. CONCLUSIONS.­: About half of group 3 cases were classified as HER2 positive after additional workup. Pathologic complete response rates in HER2-positive cases were lower than expected for group 1 (HER2:CEP17 ratio ≥2.0; HER2 copy number ≥4.0) patients. IHC targeted FISH recounts may be redundant and may potentially lead to classification of some patients as HER2 negative, resulting in withholding of targeted therapy.

Recommendations for the Use of in Silico Approaches for Next-Generation Sequencing Bioinformatic Pipeline Validation: A Joint Report of the Association for Molecular Pathology, Association for Pathology Informatics, and College of American Pathologists.

In silico approaches for next-generation sequencing (NGS) data modeling have utility in the clinical laboratory as a tool for clinical assay validation. In silico NGS data can take a variety of forms, including pure simulated data or manipulated data files in which variants are inserted into existing data files. In silico data enable simulation of a range of variants that may be difficult to obtain from a single physical sample. Such data allow laboratories to more accurately test the performance of clinical bioinformatics pipelines without sequencing additional cases. For example, clinical laboratories may use in silico data to simulate low variant allele fraction variants to test the analytical sensitivity of variant calling software or simulate a range of insertion/deletion sizes to determine the performance of insertion/deletion calling software. In this article, the Working Group reviews the different types of in silico data with their strengths and limitations, methods to generate in silico data, and how data can be used in the clinical molecular diagnostic laboratory. Survey data indicate how in silico NGS data are currently being used. Finally, potential applications for which in silico data may become useful in the future are presented.

Quantitative Imaging Analysis Fluorescence In Situ Hybridization Validation for Clinical HER2 Testing in Breast Cancer.

CONTEXT.­: Quantitative imaging is a promising tool that is gaining wide use across several areas of pathology. Although there has been increasing adoption of morphologic and immunohistochemical analysis, the adoption of evaluation of fluorescence in situ hybridization (FISH) on formalin-fixed, paraffin-embedded tissue has been limited because of complexity and lack of practice guidelines. OBJECTIVE.­: To perform human epidermal growth factor receptor 2 (HER2) FISH validation in breast carcinoma in accordance with the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2018 guideline. DESIGN.­: Clinical validation of HER2 FISH was performed using the US Food and Drug Administration-approved dual-probe HER2 IQFISH (Dako, Carpinteria, California) with digital scanning performed on a PathFusion (Applied Spectral Imaging, Carlsbad, California) system. Validation parameters evaluated included z-stacking, classifier, accuracy, precision, software, and hardware settings. Finally, we evaluated the performance of digital enumeration on clinical samples in a real-world setting. RESULTS.­: The accuracy samples showed a final concordance of 95.3% to 100% across HER2 groups 1 to 5. During clinical implementation for HER2 groups 2, 3, and 4, we achieved a final concordance of 76% (95 of 125). Of these cases, only 8% (10 of 125) had discordances with clinical impact that could be identified algorithmically and triaged for manual review. CONCLUSIONS.­: Digital FISH enumeration is a useful tool to improve the efficacy of HER2 FISH enumeration and capture genetic heterogeneity across HER2 signals. Excluding cases with high background or poor image quality and manual review of cases with ASCO/CAP group discordances can further improve the efficiency of digital HER2 FISH enumeration.

Digital imaging correlation of immunohistochemistry and fluorescence in situ hybridization in breast carcinoma cases with HER2 genetic heterogeneity.

Genetic heterogeneity (GH) is a rare but important event in the evaluation of HER2 amplification status. We investigated whether HER2 fluorescence in situ hybridization (FISH) GH correlated with increased protein expression by immunohistochemistry (IHC) and/or morphologic features using image analyses. Retrospective search of HER2 FISH GH cases 2016-2020 was performed. Cases with both FISH and IHC slides available were considered eligible and were digitally imaged. Additional demographic, histological, and treatment information was compiled from pathology and medical records when available. Overall, 11 of 15 cases (73.3%) had HER2 FISH GH that matched to areas of HER2 overexpression or focally different morphology. Nine cases with areas of gene amplification overlapped with <10% of intense circumferential protein expression ("Mini 3+"), and 1 case with focal micropapillary features. Clinical information was available on 6 patients (40%), all were alive with no evidence of disease (mean follow-up 30.5 months; range, 12-65 months). One patient with GH and a lymph node metastasis showed nonamplified population in the nodal tumor. GH, when defined as discrete clusters of amplified cells following 2013 ASCO/CAP guidelines, even when less than 10% of the tumor cells, frequently has morphologic correlates such as focal intense protein overexpression or micropapillary morphology. Clinical significance of these focal gene amplification and protein overexpression needs to be further investigated.

Divergent evolutionary trajectories shape the postmating transcriptional profiles of conspecifically and heterospecifically mated cactophilic Drosophila females.

Postmating-prezygotic (PMPZ) reproductive isolation is hypothesized to result from divergent coevolutionary trajectories of sexual selection and/or sexual conflict in isolated populations. However, the genetic basis of PMPZ incompatibilities between species is poorly understood. Here, we use a comparative framework to compare global gene expression in con- and heterospecifically mated Drosophila mojavensis and D. arizonae female reproductive tracts. We find striking divergence between the species in the female postmating transcriptional response to conspecific mating, including differences in differential expression (DE), alternative splicing (AS), and intron retention (IR). As predicted, heterospecific matings produce disrupted transcriptional profiles, but the overall patterns of misregulation are different between the reciprocal crosses. Moreover, we find a positive correlation between postmating transcriptional divergence between species and levels of transcriptional disruption in heterospecific crosses. This result indicates that mating responsive genes that have diverged more in expression also have more disrupted transcriptional profiles in heterospecifically mated females. Overall, our results provide insights into the evolution of PMPZ isolation and lay the foundation for future studies aimed at identifying specific genes involved in PMPZ incompatibilities and the evolutionary forces that have contributed to their divergence in closely related species.

Histopathological Correlation of Chromosome 12 Polysomy by Fluorescence in Situ Hybridization in Adipocytic Neoplasms.

Background: Identification of MDM2 amplification by fluorescence in situ hybridization is an important diagnostic tool for evaluation of adipocytic neoplasms. Rarely, neoplasms can show increased copies of MDM2 and CEP12 probes (polysomy) without amplification (MDM2/CEP12 ratio <2.0). While noted in the literature, this finding has not been the focus of any study to date. Methods: Consecutive cases were retrospectively screened for increased copies of MDM2 and CEP12 and were classified as: high polysomy (ratio<2.0, CEP12≥10.0), low polysomy (ratio<2.0, but >0.5, CEP12≥4.0 but <9.9), and CEP12 amplification (ratio≤0.5, CEP12 > 4.0). H&E slides were classified by a pathologist into diagnostic categories based on morphology without knowledge of MDM2 amplification result. Correlations between chromosome 12 polysomy and histological features in the same region of the tumor were investigated. Results: There were 19 (0.7%) high polysomy, 52 (2.0%) low polysomy and 3 (0.1%) CEP12 amplification cases identified in the 2541 cases screened. While low polysomy was seen across benign and malignant adipocytic tumors and other sarcomas, high level polysomy was primarily seen in liposarcomas, both atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) and dedifferentiated liposarcoma (DDLPS). No lipomas were high polysomy. Conclusion: Polysomy is an uncommon, but distinct, finding in adipocytic neoplasms found across the spectrum of benign to malignant with little insight into the pathophysiology or prognosis. While low polysomy is also observed in benign adipocytic neoplasms, high polysomy is almost always seen in malignant adipocytic neoplasms and is uncommon in benign adipocytic neoplasms.

Nodular lymphocyte predominant Hodgkin lymphoma and diffuse large B-cell lymphoma: a study of six cases concurrently involving the same site.

AIMS: Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a slowly progressing neoplasm with a favourable prognosis. However, in a minority of cases (3-12%) it progresses to a clonally related diffuse large B-cell lymphoma (DLBCL), diagnosed between 6 months and 24 years after NLPHL. This study investigated six cases of NLPHL and DLBCL at the same location. METHODS AND RESULTS: The patients were five men and one woman. In four cases, the site was an axillary lymph node, and in two it was inguinal. In all cases, NLPHL areas had typical morphological and immunophenotypic features. DLBCL involvement was multifocal, diffuse, and characterized by large centroblastic and anaplastic cells. Immunohistochemical studies showed DLBCL cells to be positive for CD20, CD45, and BCL6. In one case, DLBCL cells were positive for BCL2, and in two cases they were positive for MUM-1. There were no networks of follicular dendritic cells (FDC) associated with DLBCL. Rosettes of PD-1-positive and CD57-positive cells surrounding malignant cells in NLPHL were absent in DLBCL. All the cases were negative for Epstein-Barr virus. No translocations involving MYC were identified in DLBCL. Treatment and outcome were known in four cases. All of these patients were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), and this was followed by clinical remission (CR). CONCLUSIONS: In adequately sampled tumors, DLBCL can be associated with NLPHL at diagnosis. Diffuse architecture, loss of FDC networks, sometimes immunophenotype shift are characteristics of DLBCL associated with NLPHL. Treatment with R-CHOP usually leads to CR.

Novel ophthalmic pathology in an autopsy case of autosomal dominant retinal vasculopathy with cerebral leukodystrophy.

Autosomal dominant retinocerebral vasculopathy with cerebral leukodystrophy (RVCL) is a rare neurovascular syndrome causing retinal and central nervous system vasculopathy often recognized as contrast-enhancing white matter changes or pseudotumors on imaging. Heterozygous frameshift mutations in the 3-prime repair exonuclease 1 gene have been identified in families affected by RVCL. Variable light microscopic findings and a characteristic ultrastructural appearance of the vasculature in the brain have been reported. Description of the ophthalmic histopathology is exceedingly rare. Here, we report previously undescribed bilateral eye findings in a patient diagnosed with RVCL. The ophthalmic pathology includes thickening and reduplication of the retinal capillary basal lamina demonstrated by electron microscopy. These findings expand what is known about this disease and help further delineate its phenotype.

Small Cell Variant of Medullary Thyroid Carcinoma: A Possible Treatment.

Small cell variant of medullary thyroid carcinoma is an extremely rare histologic entity with a paucity of data. As such, there is a lack of literature and clinical experience regarding this disease. In this report, we examine a case of small cell variant of medullary thyroid carcinoma that presented with intractable nausea, vomiting and diarrhea. While these symptoms were essentially refractory to the standard symptomatic treatment, further laboratory analysis revealed dramatically elevated calcitonin levels and mildly raised thyroid-stimulating hormone levels. Interestingly, repletion of thyroid hormone and treatment with lanreotide resulted in an abatement of our patient's symptoms. This temporal clinical improvement highly suggests a potential role involving thyroid-stimulating hormone and calcitonin levels in the pathogenesis of this disease, and consequently suggests a role for thyroxine in treating the associated gastrointestinal symptoms.

Contributions of cis- and trans-Regulatory Evolution to Transcriptomic Divergence across Populations in the Drosophila mojavensis Larval Brain.

Natural selection on gene expression was originally predicted to result primarily in cis- rather than trans-regulatory evolution, due to the expectation of reduced pleiotropy. Despite this, numerous studies have ascribed recent evolutionary divergence in gene expression predominantly to trans-regulation. Performing RNA-seq on single isofemale lines from genetically distinct populations of the cactophilic fly Drosophila mojavensis and their F1 hybrids, we recapitulated this pattern in both larval brains and whole bodies. However, we demonstrate that improving the measurement of brain expression divergence between populations by using seven additional genotypes considerably reduces the estimate of trans-regulatory contributions to expression evolution. We argue that the finding of trans-regulatory predominance can result from biases due to environmental variation in expression or other sources of noise, and that cis-regulation is likely a greater contributor to transcriptional evolution across D. mojavensis populations. Lastly, we merge these lines of data to identify several previously hypothesized and intriguing novel candidate genes, and suggest that the integration of regulatory and population-level transcriptomic data can provide useful filters for the identification of potentially adaptive genes.

Cut umbilical cord milking: an ineffective method of placental transfusion in preterm infants?

Objective: To determine if umbilical cord milking performed on a cut umbilical cord segment increased the hemoglobin/hematocrit, with a reduction in the incidence of intraventricular hemorrhage, need for blood transfusions, and pressor requirement in infants with <35-weeks gestation.Study design: This was a single center, observational study in the NICU. One-hundred-six neonates received cut umbilical cord milking and two hundred ninety seven served as historical controls.Result: There were no statistically significant differences between the two groups in hemoglobin/hematocrit, peak bilirubin values, the incidence of intraventricular hemorrhage, need for blood transfusions, and the use of pressors.Conclusion: This is the first study using the cut umbilical cord milking technique that includes neonates with <35-weeks gestation. The procedure is safe but did not result in an increase in hemoglobin/hematocrit, nor did it reduce the incidence of intraventricular hemorrhage, need for blood transfusions, and pressor use.

Multi-Institutional Evaluation of Interrater Agreement of Variant Classification Based on the 2017 Association for Molecular Pathology, American Society of Clinical Oncology, and College of American Pathologists Standards and Guidelines for the Interpretation and Reporting of Sequence Variants in Cancer.

This multi-institutional study was undertaken to evaluate interrater reliability of the 2017 Association for Molecular Pathology/American Society of Clinical Oncology/College of American Pathologists guidelines for interpretation and reporting of oncology sequence variants and to assess current practices and perceptions surrounding these guidelines. Fifty-one variants were distributed to 20 participants from 10 institutions for classification using the new guidelines. Agreement was assessed using chance-corrected agreement (Cohen κ). κ was 0.35. To evaluate if data sharing could help resolve disagreements, a summary of variant classifications and additional information about each variant were distributed to all participants. κ improved to 0.7 after the original classifications were revised. Participants were invited to take a web-based survey regarding their perceptions of the guidelines. Only 20% (n = 3) of the survey respondents had prior experience with the guidelines in clinical practice. The main perceived barriers to guideline implementation included the complexity of the guidelines, discordance between clinical actionability and pathobiologic relevance, lack of familiarity with the new classifications, and uncertainty when applying criteria to potential germline variants. This study demonstrates noteworthy discordances between pathologists for variant classification in solid tumors when using the 2017 Association for Molecular Pathology/American Society of Clinical Oncology/College of American Pathologists guidelines. These findings highlight potential areas for clarification/refinement before mainstream clinical adoption.

Quantitative proteomics investigation of pancreatic intraepithelial neoplasia.

Patients with pancreatic cancer are usually diagnosed at late stages, when the disease is incurable. Pancreatic intraepithelial neoplasia (PanIN) 3 is believed to be the immediate precursor lesion of pancreatic adenocarcinoma, and would be an ideal stage to diagnose patients, when intervention and cure are possible and patients are curable. In this study, we used quantitative proteomics to identify dysregulated proteins in PanIN 3 lesions. Altogether, over 200 dysregulated proteins were identified in the PanIN 3 tissues, with a minimum of a 1.75-fold change compared with the proteins in normal pancreas. These dysregulated PanIN 3 proteins play roles in cell motility, the inflammatory response, the blood clotting cascade, the cell cycle and its regulation, and protein degradation. Further network analysis of the proteins identified c-MYC as an important regulatory protein in PanIN 3 lesions. Finally, three of the overexpressed proteins, laminin beta-1, galectin-1, and actinin-4 were validated by immunohistochemistry analysis. All three of these proteins were overexpressed in the stroma or ductal epithelial cells of advanced PanIN lesions as well as in pancreatic cancer tissue. Our findings suggest that these three proteins may be useful as biomarkers for advanced PanIN and pancreatic cancer if further validated. The dysregulated proteins identified in this study may assist in the selection of candidates for future development of biomarkers for detecting early and curable pancreatic neoplasia.

Utility of diagnostic and prognostic markers in urothelial carcinoma of the bladder.

Urothelial carcinoma (UCC) of the bladder demonstrates diverse morphologic features, often leading to diagnostic challenges in the discrimination between UCC and benign mimickers of neoplasia, and between primary UCC and secondary neoplasms involving the bladder. In situ lesions also provide diagnostic difficulty in some instances, most prominently in the distinction between normal, reactive urothelium and flat urothelial carcinoma in situ. The use of ancillary techniques, including panels of immunohistochemical markers, in distinguishing these entities has aided not only in the diagnosis of UCC, but has also provided insight into the molecular pathogenesis and prognostic value of numerous molecular pathways in UCC. This review focuses on some of the more commonly encountered biomarkers in UCC and their role in addressing key diagnostic and prognostic issues in this disease process.

Assessing the Architecture of Drosophila mojavensis Locomotor Evolution with Bulk Segregant Analysis.

Behavior is frequently predicted to be especially important for evolution in novel environments. If these predictions are accurate, there might be particular patterns of genetic architecture associated with recently diverged behaviors. Specifically, it has been predicted that behaviors linked to population divergence should be underpinned by a few genes of relatively large effect, compared to architectures of intrapopulation behavioral variation, which is considered to be highly polygenic. More mapping studies of behavioral variation between recently diverged populations are needed to continue assessing the generality of these predictions. Here, we used a bulk segregant mapping approach to dissect the genetic architecture of a locomotor trait that has evolved between two populations of the cactophilic fly Drosophila mojavensis We created an F8 mapping population of 1,500 individuals from advanced intercross lines and sequenced the 10% of individuals with the highest and lowest levels of locomotor activity. Using three alternative statistical approaches, we found strong evidence for two relatively large-effect QTL that is localized in a region homologous to a region of densely packed behavior loci in Drosophila melanogaster, suggesting that clustering of behavior genes may display relatively deep evolutionary conservation. Broadly, our data are most consistent with a polygenic architecture, though with several loci explaining a high proportion of variation in comparison to similar behavioral traits. We further note the presence of several antagonistic QTL linked to locomotion and discuss these results in light of theories regarding behavioral evolution and the effect size and direction of QTL for diverging traits in general.

American Society of Clinical Oncology/College of American Pathologists 2018 Focused Update of Breast Cancer HER2 FISH Testing GuidelinesResults From a National Reference Laboratory.

OBJECTIVES: To review impact of the ASCO/CAP 2018 update on HER2 testing. METHODS: HER2 fluorescence in situ hybridization (FISH) test requests from primary and metastatic breast cancers between August 2018 and January 2019 were included. FISH results requiring a changed algorithm under the new guidelines (groups 2, 3, and 4) were identified and HER2:CEN17 ratios, average HER2, CEN17 signals/cell, and HER2 immunohistochemistry (IHC) results were recorded. RESULTS: Of the HER2 FISH cases 176/812(21.7%) fell within groups 2, 3, or 4; 0/12, 1/12, and 2/152 cases were positive (3+) by IHC, and 1/12, 2/12, and 6/152 cases were positive after targeted scoring from groups 2, 3, and 4, respectively. Following 2018 updates, 8.3%, 25%, and 5.3% of the groups 2, 3, and 4 were positive, respectively. CONCLUSIONS: Groups 2, 3, and 4 constituted over 20% of HER2 FISH tests in a reference laboratory. The 2018 ASCO/CAP update significantly decreased the HER2 positivity rate.

Behavioral evolution accompanying host shifts in cactophilic Drosophila larvae.

For plant utilizing insects, the shift to a novel host is generally accompanied by a complex set of phenotypic adaptations. Many such adaptations arise in response to differences in plant chemistry, competitive environment, or abiotic conditions. One less well-understood factor in the evolution of phytophagous insects is the selective environment provided by plant shape and volume. Does the physical structure of a new plant host favor certain phenotypes? Here, we use cactophilic Drosophila, which have colonized the necrotic tissues of cacti with dramatically different shapes and volumes, to examine this question. Specifically, we analyzed two behavioral traits in larvae, pupation height, and activity that we predicted might be related to the ability to utilize variably shaped hosts. We found that populations of D. mojavensis living on lengthy columnar or barrel cactus hosts have greater activity and pupate higher in a laboratory environment than populations living on small and flat prickly pear cactus cladodes. Crosses between the most phenotypically extreme populations suggest that the genetic architectures of these behaviors are distinct. A comparison of activity in additional cactophilic species that are specialized on small and large cactus hosts shows a consistent trend. Thus, we suggest that greater motility and an associated tendency to pupate higher in the laboratory are potential larval adaptations for life on a large plant where space is more abundant and resources may be more sparsely distributed.

Osteoarthritis-Like Changes in Bardet-Biedl Syndrome Mutant Ciliopathy Mice (Bbs1M390R/M390R): Evidence for a Role of Primary Cilia in Cartilage Homeostasis and Regulation of Inflammation.

Osteoarthritis (OA) is a debilitating inflammation related disease characterized by joint pain and effusion, loss of mobility, and deformity that may result in functional joint failure and significant impact on quality of life. Once thought of as a simple "wear and tear" disease, it is now widely recognized that OA has a considerable metabolic component and is related to chronic inflammation. Defects associated with primary cilia have been shown to be cause OA-like changes in Bardet-Biedl mice. We examined the role of dysfunctional primary cilia in OA in mice through the regulation of the previously identified degradative and pro-inflammatory molecular pathways common to OA. We observed an increase in the presence of pro-inflammatory markers TGFß-1 and HTRA1 as well as cartilage destructive protease MMP-13 but a decrease in DDR-2. We observed a morphological difference in cartilage thickness in Bbs1 M390R/M390R mice compared to wild type (WT). We did not observe any difference in OARSI or Mankin scores between WT and Bbs1M390R/M390R mice. Primary cilia appear to be involved in the upregulation of biomarkers, including pro-inflammatory markers common to OA.