Activation of the endothelium by IL-1α and glucocorticoids results in major increase of complement C3 and factor B production and generation of C3a

International audienceConstitutive secretion of complement C3 and factor B by the endothelial cell (EC) is lowered by therapeutic concentrations of glucocorticoids such as hydrocortisone or dexamethasone, whereas regulatory protein factor H production is increased by these hormones. In contrast, the proinflammatory cytokine IL-1 alpha has a stimulatory effect on C3 and factor B secretion by the endothelium and an inhibitory effect on factor H secretion. In this study, we examined the combined effect of IL-1 alpha and glucocorticoids on C3 and factor B expression by the endothelial cell. When dexamethasone or hydrocortisone were added to IL-1 alpha, significant potentialization of IL-1 alpha-induced stimulation of C3 and factor B production was observed, occurring at various concentrations of either stimuli. Dose-response experiments indicate that, in vitro, optimal concentrations are in the range of 10(-7) to 10(-5) M for dexamethasone and 50-200 U for IL-1 alpha. In contrast, dexamethasone counteracts, in an additive way, the inhibitory effect of IL-1 alpha on regulatory complement protein factor H production by EC. Such a potentialization between glucocorticoids and IL-1 alpha was not observed for another marker of endothelial activation, IL-1 alpha-induced stimulation of coagulation tissue factor expression. The association of glucocorticoids and IL-1 alpha therefore appears to be a specific and major stimulus for the secretion of complement C3 and factor B, two acute-phase proteins, by the endothelium. As a result of the in vitro endothelium stimulation by glucocorticoids and IL-1 alpha, C3a is generated in the vicinity of the endothelial cell. This study further suggests that complement activation, with its deleterious consequences, may result from the stimulation of endothelium in situations where high levels of IL-1 alpha and endogenous glucocorticoids coexist, such as in septic shock

mCNA : a new methodology to improve high-resolution copy number variation analysis from next generation sequencing using unique molecular identifiers.

International audienc

mCNA : a new methodology to improve high-resolution copy number variation analysis from next generation sequencing using unique molecular identifiers.

International audienc

The endothelium is an extrahepatic site of synthesis of the seventh component of the complement system

The level of the terminal complement components secreted by human umbilical vein endothelial cells (HUVEC) was measured by a sensitive ELISA which allows the detection of 30–50 pg/ml of these components. C7 was the only terminal component detected in measurable amounts in the cell supernatant. The mean value was 11 ng/106 cells at 96 h and was slightly higher than that of C3 (9 ng/106 cells). HUVEC and serum C7 analysed by SDS–PAGE and immunoblot exhibited the same electrophoretic mobility. A proportion of C7 secreted by HUVEC was incorporated into the terminal complement complex (TCC) assembled spontaneously in the supernatant of cells cultured in C7-deficient human serum, and was not detected by the standard ELISA for C7 measurement. By adding the amount of C7 present in the TCC to that of free C7, the total amount of the component released by HUVEC was calculated to be approximately 35 ng/106 cells. Further TCC was produced following complement activation of the cell supernatant through the alternative pathway. Synthesis of C7 by HUVEC was confirmed by inhibition experiments in the presence of cycloheximide and by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of C7 mRNA expression. Addition of IL-1α and tumour necrosis factor-alpha to the cell culture stimulated the secretion of C3, but had no effect on the synthesis of C7. By contrast, interferon-gamma had only a marginal effect on the production of C3, but markedly down-regulated the synthesis of C7 as assessed both by ELISA and RT-PCR

High frequency of potentially pathogenic SORL1 mutations in autosomal dominant early-onset Alzheimer disease.

International audiencePerforming exome sequencing in 14 autosomal dominant early-onset Alzheimer disease (ADEOAD) index cases without mutation on known genes (amyloid precursor protein (APP), presenilin1 (PSEN1) and presenilin2 (PSEN2)), we found that in five patients, the SORL1 gene harbored unknown nonsense (n=1) or missense (n=4) mutations. These mutations were not retrieved in 1500 controls of same ethnic origin. In a replication sample, including 15 ADEOAD cases, 2 unknown non-synonymous mutations (1 missense, 1 nonsense) were retrieved, thus yielding to a total of 7/29 unknown mutations in the combined sample. Using in silico predictions, we conclude that these seven private mutations are likely to have a pathogenic effect. SORL1 encodes the Sortilin-related receptor LR11/SorLA, a protein involved in the control of amyloid beta peptide production. Our results suggest that besides the involvement of the APP and PSEN genes, further genetic heterogeneity, involving another gene of the same pathway is present in ADEOAD