Lupus anticoagulant identifies two distinct groups of patients with different antibody patterns

Background: Whether antibodies directed to β2-Glycoprotein I (aβ2GPI) are responsible for LA activity is not well defined. However, in the absence of such antibodies the molecule responsible for LA phenomenon is unknown. Objective: The aim of this study was the biochemical identification of the target antigen epitope of aPL responsible of LA activity in the absence of aβ2GPI antibodies together with the biological and clinical characteristics of these patients in comparison with classical triple positive patients. Patients/methods: A comparison of patients with LA without (LA+/aβ2GPI−) and those with (LA+/aβ2GPI+) associated aβ2GPI antibodies was performed. Size exclusion chromatography and analytical chromatography were used to identify the molecule with LA activity in patients LA+/aβ2GPI-. Results and conclusions: Analytical size-exclusion chromatography revealed a peak of 996Kd with LA activity perfectly overlapping that of IgM anti phosphatidylserine/prothrombin (aPS/PT) antibodies. Similarly, all the 25 LA+/aβ2GPI− patients were positive for aPS/PT antibodies. LA+/aβ2GPI− compared to 33 LA+/aβ2GPI+ patients turned out to be significantly older, with a lower rate of previous thromboembolic events and a weaker LA activity. Search for aPS/PT and aβ2GPI antibodies in patients with LA is useful to identify two subgroups of LA at different risk of thromboembolic event

Effects of Notch1 knockdown on the proliferation and the differentiation of human articular chondrocytes

Purpose: Osteoarthritis (OA) is the main degenerative disease of the joint, altering the differentiation pattern of articular chondrocytes. In mouse, Notch signaling is critical regulator of cartilage development and homeostasis. In human, NOTCH1 pathway is overexpressed in OA articular cartilage compared to healthy chondrocytes. Our aim was to investigate if NOTCH1 knockdown could be a potential therapeutic approach in OA. Methods: Primary human OA articular chondrocytes were NOTCH1 silenced by siRNA and cultured in 3D up to 3 weeks. Proliferation was assessed by cell cycle and DNA quantification. Cell viability, catabolic factors release and cell differentiation were also analysed. Results: NOTCH1 silencing reduced active proliferation, but had no effects on senescence and cell cycle regulators. In 3D cultures, mimicking OA progressive differentiation, NOTCH1 silenced cells showed higher viability, reduced differentiation and matrix metalloproteases production. Conclusions : NOTCH1 silenced OA chondrocytes showed a more helthy phenotype, by reducing terminal differentiation and increasing cell viability. NOTCH1 appears a therapeutic target to reduce OA progression

Osteoarthritic Milieu Affects Adipose-Derived Mesenchymal Stromal Cells

The objective of this study was to define the effects of osteoarthritic (OA) milieu on good manufactured practice-adipose-derived mesenchymal stromal cells (GMP-ASC) that are commonly utilized in cell therapies. Two different OA milieu: OA synovial fluid (SF) and OA-conditioned medium (CM) from synoviocytes were used to treat GMP-ASC both in normoxia or hypoxia. GMP-ASC were tested for cell migration, proliferation, cytokine receptors expression (CXCR1, CXCR2, CXCR3, CXCR4, CXCR7, CCR1, CCR2, CCR3, CCR5, IL6R), and cytokines (CXCL8/IL8, CXCL10/IP10, CXCL12/SDF-1, CCL2/MCP1, CCL3/MIP1\u3b1, CCL4/MIP1\u3b2, CCL5/RANTES, IL6) release. Healthy SF was used as controls. We demonstrated that GMP-ASC show an increase in proliferation, migration, and modulation of CXCR1, CXCR3, CCR1, and CCR5 receptors in hypoxic condition. Moreover, GMP-ASC migration increased 15-fold when treated either with OA-SF or OA-CM compared with healthy SF both in normoxia and hypoxia. GMP-ASC treated in both OA milieu showed an increase in CXCR3, CCR3, and IL6R and a decrease in CCR1 and CCR2 receptors. In OA-SF, we detected higher amount of CXCL10/IP10 than in OA-CM, while CCL2/MCP1 and CCL4/MIP1\u3b2 were higher in OA-CM compared with OA-SF. CXCL10/IP10 was the only chemokine of the OA milieu, which was down-modulated after treatment with GMP-ASC. In conclusion, we demonstrated specific effects of OA milieu on both GMP-ASC proliferation, migration, and cytokine receptor expression that were strictly dependent on the inflammatory and hypoxic environment. The use of characterized OA milieu is crucial to define the therapeutic effect of GMP-ASC and indicates that CXCL10/IP10\u2013CXCR3 axis is partially involved in the GMP-ASC effect on synovial macrophages. \ua9 2019 The Authors. Journal of Orthopaedic Research\uae published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 38:336-347, 2020