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Introduction: Lupus Anticoagulant (LA) testing using dilute Russell Viper Venom Time (dRVVT) is challenging in patients receiving Direct Oral AntiCoagulants (DOAC) due to potential false positive results. In a multicenter study, we evaluated the in vitro removal of DOAC by activated charcoal (DOAC remove ®), allowing reliable dRVVT testing. Materials and Methods: Patient samples were analyzed before and after treatment with DOAC remove ® : 49 apixaban, 48 rivaroxaban, 24 dabigatran and 30 none. DOAC plasma concentrations were measured using anti-Xa or anti-IIa diluted thrombin time assays. In a subset of 28 samples, DOAC concentrations were also measured using HPLC-MS/MS following treatment with DOAC remove ®. DRVVT was performed using STA-Staclot dRVVT Screen ® /Confirm ® (Stago) or LAC-Screening ® /Confirm ® (Siemens). Results: Baseline median [min-max] concentrations were 94 [<20-479] for apixaban, 107 [<20-501] for rivaroxaban and 135 ng/mL [<20-792] for dabigatran; dRVVT screen ratio /confirm normalized ratio was positive in 47, 90 and 42 % of apixaban, rivaroxaban and dabigatran samples. Treatment with DOAC remove ® did not affect dRVVT results in non-DOAC patients while it resulted in DOAC concentrations < 20 ng/mL in 82, 98 and 100 % of samples, respectively. Concentrations were < 5 ng/mL with HPLC-MS/MS in 5 out of 10, 8 out of 10 and 7 out of 8 samples, respectively. DOAC remove ® corrected DOAC interference with dRVVT assays allowed excluding LA in 76, 85 and 95 % of the patients, respectively. without affecting dRVVT results in non-DOAC patients. Conclusion: For dRVVT testing in DOAC patients, we suggest the use of DOAC remove ® for every rivaroxaban sample, whereas it might only be used in positive apixaban and dabigatran samples. A residual DOAC interference cannot be ruled out in case of persisting dRVVT positive results after treatment with DOAC remove ®. For those with persisting positive results, LA-diagnosis using dRVVT remains questionable.

Hereditary xerocytosis is a rare red blood cell disease related to gain-of-function mutations in the FAM38A gene, encoding PIEZO1, in 90% of cases; PIEZO1 is a broadly expressed mechano-transducer that plays a major role in many cell systems and tissues that respond to mechanical stress. In erythrocytes, PIEZO1 adapts the intracellular ionic content and cell hydration status to the mechanical constraints induced by the environment. Until recently, the pathophysiology of hereditary xerocytosis was mainly believed to be based on the "PIEZO1-Gardos channel axis" in erythrocytes, according to which PIEZO1-activating mutations induce a calcium influx that secondarily activates the Gardos channel, leading to potassium and water efflux and subsequently to red blood cell dehydration. However, recent studies have demonstrated additional roles for PIEZO1 during early erythropoiesis and reticulocyte maturation, as well as roles in other tissues and cells such as lymphatic vessels, hepatocytes, macrophages and platelets that may affect the pathophysiology of the disease. These findings, presented and discussed in this review, broaden our understanding of hereditary xerocytosis beyond that of primarily being a red blood cell disease and identify potential therapeutic targets. | INTRODUCTIONThe PIEZO proteins are a family of mechano-transducers first described in a neuron derived cell line in 2010. 1 The two members are PIEZO1, encoded by FAM38A on chromosome 16, and PIEZO2, encoded by FAM38B on chromosome 18. They are expressed in many tissues. 1,2 The structure of PIEZO1 has been recently elucidated. A first description of the murine protein revealed its three-dimensional structure, consisting of a three-bladed homotrimeric transmembrane helix completed by an extracellular cap. An intra-cytoplasmic domain, split into three parts, called "beams," extends from the transmembrane domain. The C-terminal end of each monomer has an extracellular domain (ECD), which forms the cap, and an intracellular domain (CTD), which appears to be connected to the paddles by the beams and closes the inner ion pore (Figure 1). The assembly provides a hydrophilic central transmembrane duct bordered by six helices that allows the passage of ions. Thus PIEZO1 constitutes a mechanosensitive ion channel due to the flexibility of the three blades. 1 Deformation of the plasma membrane subsequent to mechanical stimulation induces rotation of the PIEZO1 blades, transmitting such deformation to the ECD and CTD domains, allowing the ion channel to open using a lever-like mechanism. 2 When a compressive force is applied parallel to the axis of the ion channel, it induces lateral membrane tension, resulting in flattening and widening of PIEZO1, which causes the pore to open and allows the passage of ions. Such deformations are reversible, and PIEZO1 returns rapidly to its original conformation. [3][4][5] After opening, PIEZO1 acts as a passive channel for mono/divalent cations depending on their extracellular-intracellular Nicolas Jankovsky and Alexis Caulier...