Erythropoietin and IGF-1 signaling synchronize cell proliferation and maturation during erythropoiesis

Tight coordination of cell proliferation and differentiation is central to red blood cell formation. Erythropoietin controls the proliferation and survival of red blood cell precursors, while variations in GATA-1/FOG-1 complex composition and concentrations drive their maturation. However, clear evidence of cross-talk between molecular pathways is lacking. Here, we show that erythropoietin activates AKT, which phosphorylates GATA-1 at Ser310, thereby increasing GATA-1 affinity for FOG-1. In turn, FOG-1 displaces pRb/E2F-2 from GATA-1, ultimately releasing free, proproliferative E2F-2. Mice bearing a Gata-1^S310A mutation suffer from fatal anemia when a compensatory pathway for E2F-2 production involving insulin-like growth factor-1 (IGF-1) signaling is simultaneously abolished. In the context of the GATA-1^V205G mutation resulting in lethal anemia, we show that the Ser310 cannot be phosphorylated and that constitutive phosphorylation at this position restores partial erythroid differentiation. This study sheds light on the GATA-1 pathways that synchronize cell proliferation and differentiation for tissue homeostasis.     

Bioactive glass 45S5 ceramic for alveolar cleft reconstruction,about 58 cases

Background

Secondary alveolar bone grafting in patients with clefts lip and palate is usually performed with iliac crest bone harvesting, however using bone substitute allow to avoid harvesting morbidity. The purpose of our study was to assess if the use of a bioactive glass ceramic is an acceptable alternative to iliac crest bone harvesting in alveolar clefts treatment.

Safety of rituximab in rheumatoid arthritis: A long-term prospective single-center study of gammaglobulin concentrations and infections

ObjectiveRituximab seems well tolerated in patients with rheumatoid arthritis (RA). However, variations in the gammaglobulin profile that might increase the infection risk have been reported. Here, our objective was to evaluate gammaglobulin concentrations and the infection risk in patients receiving rituximab therapy for RA in everyday practice.MethodsProspective single-center observational study of 65 patients with refractory RA (median age, 59 years; range, 26–83) treated with rituximab 1 g twice 15 days apart, with or without a further 1-g dose at least 6 months later depending on the clinical response. Gammaglobulins were assayed before each rituximab dose.ResultsThe median cumulative rituximab dose was 4 g (1–16) and the median time to retreatment was 8 months (6–16). Rituximab therapy significantly improved the DAS-28 score. The gammaglobulin concentration decreased significantly between the first and last rituximab dose (from 11.6 g/L [5–26] to 8.2 g/L [3–20], a ?2.6 g/L difference; P < 0.05). The decrease was larger in the 24 patients with cumulative rituximab doses greater than 5 g than in the 41 other patients (difference of ?4 vs ?2.7 g/L; P < 0.05). Three patients experienced severe infections, two in the high-dose group and one in the other group (P = 0.5).ConclusionThese data obtained in everyday practice constitute further evidence that rituximab is well-tolerated in patients with RA. Rituximab therapy was associated with a decrease in gammaglobulin concentrations that was greater in patients receiving higher cumulative doses.     

Increased risk of osteoporosis and fracture in women with systemic sclerosis: A comparative study with rheumatoid arthritis

Objective

To investigate whether women with systemic sclerosis (SSc) have an increased risk of osteoporosis (OP) and related fractures compared to a high‐risk population with rheumatoid arthritis (RA) and also healthy controls, and to determine putative specific OP and fracture risk factors.

Methods

We performed a cross‐sectional study with successive inclusion of age‐matched healthy women and women with SSc and RA. Risk factors for OP and fracture were collected for all patients. Bone mineral density (BMD) was systematically measured at the lumbar spine and total hip region with dual x‐ray absorptiometry.

Results

We included 71 women with SSc, 139 women with RA, and 227 healthy women. The prevalence of OP and fracture was similar in SSc and RA, and was for both diseases higher than in healthy controls (OP: 30% in SSc, 32% in RA, and 11% in controls; fracture: 35% in SSc, 33% in RA, and 10% in controls). Multivariate analysis identified age as a risk factor of OP in SSc. Age and low 25‐hydroxyvitamin D (25[OH]D) levels were recognized as risk factors of fracture in SSc. In comparison, age and corticosteroid treatment were associated with OP in RA. Multivariate analysis confirmed age, OP, and low 25(OH)D levels as independent risk factors of fractures in RA.

Conclusion

The prevalence of OP and fracture in SSc was increased compared to healthy women and reached the high prevalence associated with RA. Age and vitamin D deficiency were identified as risk factors of fracture in SSc. Therefore, increasing the awareness and performance of BMD measurements together with the vitamin D supply in patients with SSc is warranted.     

Bidirectional association between physical activity and symptoms of anxiety and depression: the Whitehall II study

Although it has been hypothesized that the association of physical activity with depressive and anxiety symptoms is bidirectional, few studies have examined this issue in a prospective setting. We studied this bidirectional association using data on physical activity and symptoms of anxiety and depression at three points in time over 8?years. A total of 9,309 participants of the British Whitehall II prospective cohort study provided data on physical activity, anxiety and depression symptoms and 10 covariates at baseline in 1985. We analysed the associations of physical activity with anxiety and/or depression symptoms using multinomial logistic regression (with anxiety and depression symptoms as dependent variables) and binary logistic regression (with physical activity as the dependent variable). There was a cross-sectional inverse association between physical activity and anxiety and/or depressive symptoms at baseline (ORs between 0.63 and 0.72). In cumulative analyses, regular physical activity across all three data waves, but not irregular physical activity, was associated with reduced likelihood of depressive symptoms at follow-up (OR?=?0.71, 95?% CI 0.54, 0.99). In a converse analysis, participants with anxiety and depression symptoms at baseline had higher odds of not meeting the recommended levels of physical activity at follow-up (OR?=?1.79, 95?% CI 1.17, 2.74). This was also the case in individuals with anxiety and/or depression symptoms at both baseline and follow-up (OR?=?1.70, 95?% CI 1.10, 2.63). The association between physical activity and symptoms of anxiety and/or depression appears to be bidirectional.     

Synovial fluid analysis with leukocyte esterase reagent strip test

To determine whether leukocyte esterase reagent strip test (LERST) analysis could help distinguish inflammatory arthritis from mechanical joint effusion. We analyzed synovial fluid (SF) from consecutive patients with a non-traumatic joint effusion during a 6-month period. Inflammatory SF was defined by white blood cell (WBC) count ≥ 2000/mm³. The LERST was performed with both semi-quantitative visual analysis (VA) and automated colorimetric reader (ACR) analysis. Leukocytes ≥ 1+ was considered a positive LERST result and WBC count was the reference. We obtained 100 SF samples (87 knees, 7 ankles, 5 hips, and 1 elbow) from 100 patients (mean ± SD age 61 ± 17 years, 59% men). The laboratory analyzed 88 SF samples (37 mechanical and 51 inflammatory). The remaining 12 SF samples were 10 hemarthrosis not allowing LERST analysis and 2 samples with coagulum not allowing WBC count. As compared with the laboratory analysis, the LERST had sensitivity and specificity 55% and 89% with VA and 47% and 92% with ACR analysis. The positive and negative predictive values were 87.5% and 59% with VA and 89% and 55% with ACR analysis. We found almost perfect agreement between VA and ACR results (kappa 0.70 [95% CI 0.50–0.90]). The WBC count increased with number of + observed after VA. Our results confirm that the LERST is able to detect inflammation in SF of native joints, thereby representing a useful and cheap tool in primary care. Its low sensitivity limits its use for ruling out inflammatory disorders.

Human CalDAG-GEFI gene (RASGRP2) mutation affects platelet function and causes severe bleeding

The nature of an inherited platelet disorder was investigated in three siblings affected by severe bleeding. Using whole-exome sequencing, we identified the culprit mutation (cG742T) in the RAS guanyl-releasing protein-2 (RASGRP2) gene coding for calcium- and DAG-regulated guanine exchange factor-1 (CalDAG-GEFI). Platelets from individuals carrying the mutation present a reduced ability to activate Rap1 and to perform proper αIIbβ3 integrin inside-out signaling. Expression of CalDAG-GEFI mutant in HEK293T cells abolished Rap1 activation upon stimulation. Nevertheless, the PKC- and ADP-dependent pathways allow residual platelet activation in the absence of functional CalDAG-GEFI. The mutation impairs the platelet’s ability to form thrombi under flow and spread normally as a consequence of reduced Rac1 GTP-binding. Functional deficiencies were confined to platelets and megakaryocytes with no leukocyte alteration. This contrasts with the phenotype seen in type III leukocyte adhesion deficiency caused by the absence of kindlin-3. Heterozygous did not suffer from bleeding and have normal platelet aggregation; however, their platelets mimicked homozygous ones by failing to undergo normal adhesion under flow and spreading. Rescue experiments on cultured patient megakaryocytes corrected the functional deficiency after transfection with wild-type RASGRP2. Remarkably, the presence of a single normal allele is sufficient to prevent bleeding, making CalDAG-GEFI a novel and potentially safe therapeutic target to prevent thrombosis.Inherited platelet disorders are rare diseases that give rise to bleeding when platelets fail to fulfill their hemostatic function upon vessel injury. Clinical manifestations include mainly mucocutaneous bleeding, menometrorrhagia and excessive bleeding after surgical intervention or trauma. The study of these diseases allows a better understanding of normal platelet biochemistry and physiology. These inherited disorders include abnormalities of platelet receptors, granules, or signal transduction (Nurden and Nurden, 2011). Signal transduction dysfunction is thought to be the most common cause of platelet inherited disorders; however, only a few have been successfully genotyped.Here, we have identified and characterized the first mutation of RASGRP2 (RAS guanyl-releasing protein-2) in a family suffering severe bleeding. RASGRP2 codes for a major signaling molecule in platelets, calcium-and-DAG-regulated guanine exchange factor-1 (CalDAG-GEFI). It is a guanine nucleotide exchange factor (GEF) that is critical for Ras-like GTPase activation whose target is mainly Rap1 in platelets (Crittenden et al., 2004; Bergmeier et al., 2007; Cifuni et al., 2008; Stefanini et al., 2009). Rap1 is one of the most predominant small GTPases in platelets and constitutes a key signaling element that governs platelet activation by directly regulating integrin-mediated aggregation and granule secretion (Chrzanowska-Wodnicka et al., 2005; Zhang et al., 2011). Mice lacking CalDAG-GEFI not only have major defects in platelet function, with a reduced ability to form thrombi upon vascular injury, but they also have impaired neutrophil functions (Crittenden et al., 2004; Bergmeier et al., 2007; Carbo et al., 2010). To date, no pathological mutation in RASGRP2 has been reported in man and knowledge about the phenotype linked to human CalDAG-GEFI deficiency is lacking.