Knock-in of murine Calr del52 induces essential thrombocythemia with slow-rising dominance in mice and reveals key role of Calr exon 9 in cardiac development.
- 作者列表："Balligand T","Achouri Y","Pecquet C","Gaudray G","Colau D","Hug E","Rahmani Y","Stroobant V","Plo I","Vainchenker W","Kralovics R","Van den Eynde BJ","Defour JP","Constantinescu SN
:Frameshifting mutations (-1/+2) of the calreticulin (CALR) gene are responsible for the development of essential thrombocythemia (ET) and primary myelofibrosis (PMF). The mutant CALR proteins activate the thrombopoietin receptor (TpoR) inducing cytokine-independent megakaryocyte progenitor proliferation. Here, we generated via CRISPR/Cas9 technology two knock-in mouse models that are heterozygous for a type-I murine Calr mutation. These mice exhibit an ET phenotype with elevated circulating platelets compared with wild-type controls, consistent with our previous results showing that murine CALR mutants activate TpoR. We also show that the mutant CALR proteins can be detected in plasma. The phenotype of Calr del52 is transplantable, and the Calr mutated hematopoietic cells have a slow-rising advantage over wild-type hematopoiesis. Importantly, a homozygous state of a type-1 Calr mutation is lethal at a late embryonic development stage, showing narrowed ventricular myocardium walls, similar to the murine Calr knockout phenotype, pointing to the C terminus of CALR as crucial for heart development.
: 钙网蛋白 (CALR) 基因的移码突变 (-1/+ 2) 负责原发性血小板增多症 (ET) 和原发性骨髓纤维化 (PMF) 的发展。突变型CALR蛋白激活血小板生成素受体 (TpoR) 诱导细胞因子非依赖性巨核细胞祖细胞增殖。在这里，我们通过CRISPR/Cas9技术产生了两种敲入小鼠模型，它们是I型鼠Calr突变的杂合模型。与野生型对照相比，这些小鼠表现出具有升高的循环血小板的ET表型，这与我们先前显示鼠CALR突变体激活TpoR的结果一致。我们还表明突变CALR蛋白可以在血浆中检测到。Calrdel52的表型是可移植的，并且Calr突变的造血细胞相对于野生型造血具有缓慢上升的优势。重要的是，1型Calr突变的纯合状态在胚胎发育后期是致命的，显示出狭窄的心肌壁，类似于鼠Calr敲除表型，指出CALR的C末端对心脏发育至关重要。
METHODS::Vancomycin (VCM) has been reported to elicit adverse cutaneous drug reactions. However, VCM-associated purpuric drug eruption has not been reported yet, except leukocytoclastic vasculitis. A 16-year-old Japanese girl was admitted with a respiratory infection. We initiated intravenous administration of VCM. After the start of treatment, impalpable purpuric eruption appeared on her trunk. The eruption gradually extended to her neck, legs, and arms. Skin biopsy showed vasculitis with lymphocyte infiltration in the superficial dermis. A drug lymphocyte stimulation test yielded positive results for VCM. Her cutaneous symptoms rapidly reversed after the withdrawal of VCM. To the best of our knowledge, this is the first reported case of VCM-associated purpuric drug eruption, which differs from leukocytoclastic vasculitis. We recommend that VCM-associated purpuric drug eruption should be considered in the differential diagnosis during the administration of VCM, and a drug lymphocyte stimulation test may be useful for assessment of pathogenesis.
METHODS::The cardinal biological role of vitamin K is to act as cofactor for the carboxylation of a number of vitamin K-dependent proteins, some of which are essential for coagulation, bone formation and prevention of vascular calcification. Functional vitamin K deficiency is common and severe among dialysis patients and has garnered attention as a modifiable risk factor in this population. However, no single biochemical parameter can adequately assess vitamin K status. For each biological function of vitamin K, the degree of carboxylation of the relevant vitamin K-dependent protein most accurately reflects vitamin K status. Dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP) is the best biomarker for vascular vitamin K status when cardiovascular endpoints are studied. Dp-ucMGP levels are severely elevated in haemodialysis patients and correlate with markers of vascular calcification and mortality in some but not all studies. The aetiology of vitamin K deficiency in haemodialysis is multifactorial, including deficient intake, uraemic inhibition of the vitamin K cycle and possibly interference of vitamin K absorption by phosphate binders. The optimal vitamin K species, dose and duration of supplementation to correct vitamin K status in dialysis patients are unknown. Dp-ucMGP levels dose-proportionally decrease with supraphysiological vitamin K2 supplementation, but do not normalize even with the highest doses. In the general population, long-term vitamin K1 or K2 supplementation has beneficial effects on cardiovascular disease, bone density and fracture risk, and insulin resistance, although some studies reported negative results. In haemodialysis patients, several trials on the effects of vitamin K on surrogate markers of vascular calcification are currently ongoing.
METHODS::Immune thrombocytopenia (ITP) is an autoimmune disease with a mild to severe risk of bleeding complications. First line treatment includes corticosteroids, immunoglobulins, or other. In this large cohort study, first-line strategies for treatment-naive adult primary ITP was studied in a real-world setting. Records from all adult ITP patients who received first-line treatment between January 2010 and December 2017 at Qilu Hospital were reviewed retrospectively (n = 699). During the study period, 271 patients were treated with high-dose dexamethasone (HDD) and 289 patients were treated with conventional prednisone (alone or in combination with other drugs). Initial responses were similar for the two groups (88.56% vs. 86.51%, P = 0.462), but patients in the HDD group responded earlier than the prednisone group (3 days vs. 5 days, P < 0.001). The sustained response (SR) at 6 months was lower in the HDD group than in the prednisone group (35.4% vs. 47.1%, P = 0.040). However, the SR at 12 months and at the end of our follow-up were not significantly different between the groups. Overall duration of response (DOR) in the prednisone group was longer than in the HDD group throughout the follow-up period (P = 0.007). However, the incidence of SR and overall DOR were not significantly different between the HDD group and the prednisone 3 months group (prednisone terminated within 3 months). The presence of anti-GPIb-IX autoantibodies was a predictive factor for a poor initial response to corticosteroids therapy (P < 0.05). However, neither of the two antiplatelet autoantibodies were correlated with the opportunity to achieve SR and overall DOR in both groups throughout the follow-up period (P > 0.05). Adverse events were more frequent and long-lasting in the prednisone group. Our study showed that HDD provided an effective and more rapid response as initial treatment of ITP, with comparable long-term prognosis and better tolerance when compared with conventional PDN (less than 3 months) in the real-world setting.