Systematic identification of factors involved in the silencing of germline genes in mouse embryonic stem cells

In mammals, many germline genes are epigenetically repressed to prevent their illegitimate expression in somatic cells. To advance our understanding of the mechanisms restricting the expression of germline genes, we analyzed their chromatin signature and performed a CRISPR-Cas9 knock-out screen for genes involved in germline gene repression using a Dazl-GFP reporter system in mouse embryonic stem cells (mESCs). We show that the repression of germline genes mainly depends on the polycomb complex PRC1.6 and DNA methylation, which function additively in mESCs. Furthermore, we validated novel genes involved in the repression of germline genes and characterized three of them: Usp7, Shfm1 (also known as Sem1) and Erh. Inactivation of Usp7, Shfm1 or Erh led to the upregulation of germline genes, as well as retrotransposons for Shfm1, in mESCs. Mechanistically, USP7 interacts with PRC1.6 components, promotes PRC1.6 stability and presence at germline genes, and facilitates DNA methylation deposition at germline gene promoters for long term repression. Our study provides a global view of the mechanisms and novel factors required for silencing germline genes in embryonic stem cells

Indometacin loading and in vitro release properties from novel carbopol coated spherical mesoporous silica nanoparticles

Spherical MCM-41 silica nanosized particles were synthesized and post synthesis modified by 3-aminopropyltriethoxysilane (APTES) in order to prepare amino-functionalized carrier. Both types of silica particleswere loaded with indometacin and further coated with carbopol. The preservation of morphology and pore structure of the particles was observed by XRD, TEM and N2 physisorption. FT-IR spectroscopy revealed the interaction between carboxyl groups of indometacin and the amino groups of the functionalized MCM-41. Amino-functionalization of the carrier resulted in higher degree of indometacin loading in comparison to the parent MCM-41, 39% vs. 30%, respectively. The coating of drug loaded amino-MCM-41 silica particles with carbopol significantly reduced the initial burst release of indometacin. Both silica carriers demonstrated no cytotoxicity on HL-60 (acute myeloid leukemia) and K-562 (chronic myeloid leukemia) cell lines

E2F6 initiates stable epigenetic silencing of germline genes during embryonic development.

In mouse development, long-term silencing by CpG island DNA methylation is specifically targeted to germline genes; however, the molecular mechanisms of this specificity remain unclear. Here, we demonstrate that the transcription factor E2F6, a member of the polycomb repressive complex 1.6 (PRC1.6), is critical to target and initiate epigenetic silencing at germline genes in early embryogenesis. Genome-wide, E2F6 binds preferentially to CpG islands in embryonic cells. E2F6 cooperates with MGA to silence a subgroup of germline genes in mouse embryonic stem cells and in embryos, a function that critically depends on the E2F6 marked box domain. Inactivation of E2f6 leads to a failure to deposit CpG island DNA methylation at these genes during implantation. Furthermore, E2F6 is required to initiate epigenetic silencing in early embryonic cells but becomes dispensable for the maintenance in differentiated cells. Our findings elucidate the mechanisms of epigenetic targeting of germline genes and provide a paradigm for how transient repression signals by DNA-binding factors in early embryonic cells are translated into long-term epigenetic silencing during mouse development

Pressure ulcers are associated with 6-month mortality in elderly patients with hip fracture managed in orthogeriatric care pathway

International audienceDespite orthogeriatric management, 12% of the elderly experienced PUs after hip fracture surgery. PUs were significantly associated with a low albumin level, history of atrial fibrillation coronary artery disease, and diabetes. The risk ratio of death at 6 months associated with pressure ulcer was 2.38 (95% CI 1.31-4.32%, p = 0.044).Introduction: Pressure ulcers in hip fracture patients are frequent and associated with a poor outcome. An orthogeriatric management, recommended by international guidelines in hip fracture patients and including pressure ulcer prevention and treatment, could influence causes and consequences of pressure ulcer. However, remaining factors associated with pressure ulcer occurrence and prognostic value of pressure ulcer in hip fracture patients managed in an orthogeriatric care pathway remain unknown.Methods: From June 2009 to April 2015, all consecutive patients with hip fracture admitted to a unit for Post-operative geriatric care were evaluated for eligibility. Patients were included if their primary presentation was due to hip fracture and if they were ≥ 70 years of age. Patients were excluded in the presence of pathological fracture or if they were already hospitalized at the time of the fracture. In our unit, orthogeriatric principles are implemented, including a multi-component intervention to improve pressure ulcer prevention and management. Patients were followed-up until 6 months after discharge.Results: Five hundred sixty-seven patients were included, with an overall 14.4% 6-month mortality (95% CI 11.6-17.8%). Of these, 67 patients (12%) experienced at least one pressure ulcer. Despite orthogeriatric management, pressure ulcers were significantly associated with a low albumin level (RR 0.90, 95% CI 0.84-0.96; p = 0.003) and history of atrial fibrillation (RR 1.91, 95% CI 1.05-3.46; p = 0.033), coronary artery disease (RR 2.16, 95% CI 1.17-3.99; p = 0.014), and diabetes (RR 2.33, 95% CI 1.14-4.75; p = 0.02). A pressure ulcer was associated with 6-month mortality (RR 2.38, 95% CI 1.31-4.32, p = 0.044).Conclusion: In elderly patients with hip fracture managed in an orthogeriatric care pathway, pressure ulcer remained associated with poorly modifiable risk factors and long-term mortality

Hip Fracture Leads to Transitory Immune Imprint in Older Patients

International audienceBackground: Hip fracture (HF) is common in the geriatric population and is associated with a poor vital and functional prognosis which could be impacted by immunological changes. The objective here is to decipher immune changes occurring in the 1st days following HF and determine how phenotype, function, and regulation of innate and adaptive compartments adapt during acute stress event. Methods: We included HF patients, aged over 75 years. For each patient, blood samples were taken at five different timepoints: four in the perioperative period (day 0 to hospital discharge) and one at long term (6-12 months). Phenotypical and functional analysis were performed longitudinally on fresh blood or cryopreserved PBMCs. Clinical data were prospectively collected. Results: One-hundred HF patients and 60 age-matched controls were included. Innate compartment exhibits pro-inflammatory phenotypes (hyperleukocytosis, increase of CD14+ CD16+ proportion and CCR2 expression), maintaining its ability to produce pro-inflammatory cytokines. Adaptive compartment extends toward a transitory immunosuppressive profile (leucopenia) associated with an active T-cell proliferation. Furthermore, increases of LAG-3 and PD-1 and a decrease of 2-B4 expression are observed on T-cells, reinforcing their transitory suppressive status. Of note, these immune changes are transitory and sequential but may participate to a regulation loop necessary for homeostatic immune control at long term. Conclusion: HF is associated with several transitory immunological changes including pro-inflammatory phenotype in innate compartment and immunosuppressive profile in adaptive compartment. A comprehensive assessment of immune mechanisms implicated in the patient's prognosis after HF could pave the way to develop new immune therapeutics strategies

Prognostic Value of Serum Procalcitonin After Orthopedic Surgery in the Elderly Population

International audienceBackground: Orthopedic surgery is more and more frequent in the older patients and is associated with a high mortality rate. Although serum procalcitonin levels are associated with prognosis in young adults, data are still lacking in the elderly population, and especially after surgery. The main objective of this study was to determine the prognostic value of procalcitonin levels in a large geriatric orthopedic population, and we compared it with clinical variables and biomarkers. Methods: This is a prospective study including patients admitted in our dedicated geriatric postoperative unit, after orthopedic surgery with immediate postoperative measured procalcitonin levels. Collected data included age, sex, medical history, functional status (activities of daily living [ADL]), fracture type, Cumulative Illness Rating scale (CIRS), postoperative complications, and biological data. The primary endpoint was the 30-day mortality. Results: 436 patients (age 85 +/- 6 years) were included. Hip fracture surgery was the most frequent (n = 310; 71%), and the 30-day mortality rate was 6.9%. Compared with C-reactive protein (CRP), albumin, CIRS, and ADL, procalcitonin had the highest area under the receiver operating characteristic curve for predicting 30-day mortality (0.74; 95% CI: 0.70-0.78). Using a cutoff at 1 mu g/L, procalcitonin was more specific than CIRS to predict 30-day mortality (92 vs 77%; p <.001). In a multivariable analysis, procalcitonin level higher than 0.39 mu g/L is a significant predictor of mortality within 30 days (odds ratio 3.84; 95% CI: 1.61-9.14, p =.002). Conclusion: Elevated procalcitonin values were strongly and significantly associated with mortality within 30 days in older patients after orthopedic surgery