Cell fusion is a fundamental biological event that is essential for the development of multinucleated cells such as osteoclasts. Fusion failure leads to the accumulation of dense bone such as in osteopetrosis, demonstrating the importance of fusion in osteoclast maturity and bone remodeling. In a recent study, we reported that Pin1 plays a role in the regulation of bone formation and Runx2 regulation. In this study, we explored the role of Pin1 in osteoclast formation and bone resorption. Pin1 null mice have low bone mass and increased TRAP staining in histological sections of long bones, compared to Pin1 wild-type mice. In vitro osteoclast forming assays with bone marrow-derived monocyte/macrophage revealed that Pin1-deficient osteoclasts are larger than wild-type osteoclasts and have higher nuclei numbers, indicating greater extent of fusion. Pin1 deficiency also highly enhanced foreign body giant cell formation both in vitro and in vivo. Among the known fusion proteins, only DC-STAMP was significantly increased in Pin1(-/-) osteoclasts. Immunohistochemistry showed that DC-STAMP expression was also significantly increased in tibial metaphysis of Pin1 KO mice. We found that Pin1 binds and isomerizes DC-STAMP and affects its expression levels and localization at the plasma membrane. Taken together, our data indicate that Pin1 is a determinant of bone mass through the regulation of the osteoclast fusion protein DC-STAMP. The identification of Pin1 as a factor involved in cell fusion contributes to the understanding of osteoclast-associated diseases, including osteoporosis, and opens new avenues for therapeutic targets.

Rationale:To report the distant migration of a subdermal contraceptive implant and to suggest that C arm-guided technique is one of the feasible options for removal of the device migrated to the axilla.Patient concerns:A 41-year-old multipara with tingling sensation in the left axilla was referred for removal of an Implanon NXT which could not be palpated by physical examination or detected by ultrasound scanning. Finally, the device was detected by computed tomography and found migrating to the left axilla.Diagnosis:Migration of Implanon NXT to the left axilla abutting the brachial plexus.Interventions:The device was removed by C arm-guiding.Outcomes:The patient went home without any procedure-related complications.Lessons:The incidence of distant migration of a subdermal implant is possible and should be checked up regularly. If the device cannot be palpated or detected by ultrasound at the original implanting site, this should be concerned. Since the single-rod subdermal implant is radiopaque, it can be detected by roentgenography. In this case the distant migration was detected in the axilla, therefore using C arm-guided technique is feasible for the removal of the migrating device. After reviewing the literature, totally 10 cases of distant migration were reported including 2 cases of migration which were advanced further to the pulmonary artery as an embolization.

Purpose: To analyze occurrence and risk factors for macular edema (ME) in juvenile idiopathic arthritis-associated uveitis (JIA-U). Methods: Retrospective analysis of patients with JIA-U at a tertiary referral uveitis center between 2000 and 2019. Epidemiological data and clinical findings before ME onset were evaluated. Results: Out of 245 patients, ME developed in 41 (18%) of the 228 JIA-U patients for whom data documentation was complete during the follow-up (mean 4.0 ± 3.8 years). Risk factors (univariable logistic regression analysis) at baseline for subsequent ME onset included older age at initial documentation at institution (hazard ratio, HR 1.19, p < 0.0001), longer duration of uveitis at initial documentation (HR 1.17, p < 0.0001), worse best-corrected visual acuity (BCVA; HR 2.49, p < 0.0001), lower intraocular pressure (IOP; HR 0.88, p < 0.01), band keratopathy (HR 2.29, p < 0.01), posterior synechiae (HR 2.55, p < 0.01), epiretinal membrane formation (HR 6.19, p < 0.0001), optic disc swelling (HR 2.81, p < 0.01), and cataract (HR 4.24, p < 0.0001). Older age at initial documentation at institution (HR 1.55, p < 0.001), worse BCVA (HR 28.56, p < 0.001), and higher laser-flare photometry (LFM) values (HR 1.003, p = 0.01) were independent risk factors for ME manifestation. Patients with ME revealed significant changes in BCVA, LFM, and IOP and new optic disc swelling at 6 and 3 months before ME onset compared to timepoint of ME occurrence (p < 0.05, each). Conclusion: ME is a common complication of JIA-U. Demographic risk factors and courses of IOP, BCVA, and LFM may indicate patients at risk for ME onset.

The purposes of this study were to find a novel mutation of FGFR2 in Korean Crouzon syndrome patients and to identify the functional consequences of this mutation. The samples consisted of 16 Crouzon patients. Peripheral venous blood was collected from the patients. FGFR2 mutation screening was performed by direct PCR sequencing of all exons and part of the introns. Restriction fragment length polymorphism (RFLP) analysis was performed to confirm the novel mutation. For functional studies, we performed luciferase assay for Runx2 transcriptional activity, real-time PCR for the bone markers (osteocalcin and alkaline phosphatase), and Western blot for phosphorylated FGFR2 and ERK1/2-MAPK protein. Among 16 patients, 10 showed FGFR2 mutations that had already been reported elsewhere. A novel FGFR2 mutation associated with tyrosine kinase II (TK-II) domain, L617F, was found in one Crouzon syndrome patient by direct PCR sequencing. Presence of this mutation was confirmed using RFLP analysis. Runx2 transcriptional activity and expression of osteocalcin and alkaline phosphatase significantly increased in L617F-transfected cells compared to wild-type cells. FGFR2 autophosphorylation in L617F-transfected cells increased in 1% serum, but ERK1/2-MAPK protein was not activated. The FGFR2-L617F mutation associated with the TK domain is potentially related to premature suture closure in Crouzon syndrome patient.