Rationale: Inflammasome activation, with subsequent release of pro-inflammatory cytokines IL-1β and IL-18, has recently been implicated in atherosclerosis-associated inflammation.Objective: To assess in acute coronary syndrome (ACS) patients (1) inflammasome activation in circulating monocytes and (2) whether short-term oral colchicine, a recognised anti-inflammatory agent that has been shown to be cardio-protective in clinical studies, might acutely suppress inflammasome-dependent inflammation. Methods and Results:ACS patients (n=21) were randomised to oral colchicine (1 mg followed by 0.5 mg 1 hour later) or no treatment, and compared with untreated healthy controls (n=9). Peripheral venous blood was sampled pre-(day 1) and 24 hours post-(day 2) treatment. Monocytes were cultured and stimulated with ATP. Analysis of key inflammasome markers was performed by ELISA. IL-1β secretion increased by 580.4 % (p<0.01) in ACS patients compared to controls but only with ATP stimulation. Untreated ACS patients secreted significantly higher levels of IL-18 vs healthy controls independent of ATP stimulation (p< 0.05). Colchicine treatment in ACS patients markedly reduced intracellular and secreted levels of IL-1β vs pre-treatment levels (p<0.05 for both), as well as significantly reducing pro-caspase-1 mRNA levels by 57.7 % and secreted caspase-1 protein levels by 30.2 % vs untreated patients (p<0.05 for both). Conclusions:Monocytes from ACS patients are "primed" to secrete inflammasome-related cytokines and short-term colchicine acutely and markedly suppresses monocyte caspase-1 activity, thereby reducing monocyte secretion of IL-1β. SUMMARY STATEMENTInflammasome activation in monocytes is elevated in ACS patients versus healthy subjects.Acute colchicine therapy dramatically suppresses this activation, via inhibition of caspase-1 gene transcription leading to reduced secretion of IL-1β, supporting a beneficial role for colchicine in atherosclerosis.

First described as a variant of Larsen syndrome in Reunion Island (LRS) in the southern Indian Ocean, 'Larsen of Reunion Island syndrome' is characterized by dwarfism, hyperlaxity, multiple dislocations and distinctive facial features. It overlaps with Desbuquois dysplasia, Larsen syndrome and spondyloepiphyseal dysplasia with dislocations ascribed to CANT1, FLNB and CHST3 mutations, respectively. We collected the samples of 22 LRS cases. After exclusion of CANT1, FLNB and CHST3 genes, an exome sequencing was performed in two affected second cousins and one unaffected sister. We identified a homozygous missense mutation in B4GALT7, NM_007255.2: c.808C4T p.(Arg270Cys) named p.R270C, in the two affected cases, not present in the unaffected sister. The same homozygous mutation was subsequently identified in the remaining 20 LRS cases. Our findings demonstrate that B4GALT7 is the causative gene for LRS. The identification of a unique homozygous mutation argues in favor of a founder effect. B4GALT7 encodes a galactosyltransferase, required for the initiation of glycoaminoglycan side chain synthesis of proteoglycans. This study expands the phenotypic spectrum of B4GALT7 mutations, initially described as responsible for the progeroid variant of Ehlers-Danlos syndrome. It further supports a common physiopathological basis involving proteoglycan synthesis in skeletal disorders with dislocations.

Atypical hemolytic uremic syndrome (aHUS) is a severe disease characterized by microvascular endothelial cell (EC) lesions leading to thrombi formation, mechanical hemolysis and organ failure, predominantly renal. Complement system overactivation is a hallmark of aHUS. To investigate this selective susceptibility of the microvascular renal endothelium to complement attack and thrombotic microangiopathic lesions, we compared complement and cyto-protection markers on EC, from different vascular beds, in in vitro and in vivo models as well as in patients. No difference was observed for complement deposits or expression of complement and coagulation regulators between macrovascular and microvascular EC, either at resting state or after inflammatory challenge. After prolonged exposure to hemolysis-derived heme, higher C3 deposits were found on glomerular EC, in vitro and in vivo, compared with other EC in culture and in mice organs (liver, skin, brain, lungs and heart). This could be explained by a reduced complement regulation capacity due to weaker binding of Factor H and inefficient upregulation of thrombomodulin (TM). Microvascular EC also failed to upregulate the cytoprotective heme-degrading enzyme heme-oxygenase 1 (HO-1), normally induced by hemolysis products. Only HUVEC (Human Umbilical Vein EC) developed adaptation to heme, which was lost after inhibition of HO-1 activity. Interestingly, the expression of KLF2 and KLF4—known transcription factors of TM, also described as possible transcription modulators of HO-1- was weaker in micro than macrovascular EC under hemolytic conditions. Our results show that the microvascular EC, and especially glomerular EC, fail to adapt to the stress imposed by hemolysis and acquire a pro-coagulant and complement-activating phenotype. Together, these findings indicate that the vulnerability of glomerular EC to hemolysis is a key factor in aHUS, amplifying complement overactivation and thrombotic microangiopathic lesions.