The developmentally regulated avian Ch21 lipocalin is an extracellular fatty acid-binding protein.

Ch21, a developmentally regulated extracellular protein expressed in chick embryos and in cultured chondrocytes, was expressed in the baculovirus system, and the recombinant protein was purified to homogeneity by gel-filtration chromatography. Separation of two isoforms was achieved on an ion-exchange column. Previous work had shown that Ch21 belongs to the superfamily of lipocalins, which are transport proteins for small hydrophobic molecules. Studies were performed to identify the Ch21 ligand. By analysis of recombinant Ch21 on native polyacrylamide gel electrophoresis and by Lipidex assay, the binding of fatty acid to the protein was shown and a preferential binding of long-chain unsaturated fatty acids was observed. Both isoforms had the same behavior. The binding was saturable. Stoichiometry was about 0.7 mol of ligand/mol of protein. The protein binds the ligand in its monomeric form. Calculated dissociation constants were 2 X 10(-7) M for unsaturated fatty acids and 5 X 10(-7) M for stearic acid. The binding was specific; other hydrophobic molecules, as retinoic acid, progesterone, prostaglandins, and long-chain alcohols and aldehydes did not bind to the protein. Short-chain fatty acids did not bind to the protein. Ch21, also present in chicken serum, represents the first extracellular protein able to selectively bind and transport fatty acid in extracellular fluids and serum. We propose to rename the Ch21 protein as extracellular fatty acid-binding protein (Ex-FABP)

MiR-146b-5p regulates IL-23 receptor complex expression in chronic lymphocytic leukemia cells

Chronic lymphocytic leukemia (CLL) cells express the interleukin-23 receptor (IL-23R) chain, but the expression of the complementary IL-12R(31 chain requires cell stimulation via surface CD40 molecules (and not via the B-cell receptor [BCR]). This stimulation induces the expression of a heterodimeric functional IL-23R complex and the secretion of IL-23, initiating an autocrine loop that drives leukemic cell expansion. Based on the observation in 224 untreated Binet stage A patients that the cases with the lowest miR-146b-5p concentrations had the shortest time to first treatment (TTFT), we hypothesized that miR-146b-5p could negatively regulate IL-12R(31 side chain expression and clonal expansion. Indeed, miR-146b-5p significantly bound to the 3 '-UTR region of the IL-12R(31 mRNA in an in vitro luciferase assay. Downregulation of miR-146b-5p with specific miRNA inhibitors in vitro led to the upregulation of the IL-12R(31 side chain and expression of a functional IL-23R complex similar to that observed after stimulation of the CLL cell through the surface CD40 molecules. Expression of miR-146b-5p with miRNA mimics in vitro inhibited the expression of the IL-23R complex after stimulation with CD40L. Administration of a miR-146b-5p mimic to NSG mice, successfully engrafted with CLL cells, caused tumor shrinkage, with a reduction of leukemic nodules and of IL-12R(31-positive CLL cells in the spleen. Our findings indicate that IL-12R(31 expression, a crucial checkpoint for the functioning of the IL-23 and IL-23R complex loop, is under the control of miR-146b-5p, which may represent a potential target for therapy since it contributes to the CLL pathogenesis. This trial is registered at www.clinicaltrials.gov as NCT00917540

Outcomes in Newly Diagnosed Atrial Fibrillation and History of Acute Coronary Syndromes: Insights from GARFIELD-AF

BACKGROUND: Many patients with atrial fibrillation have concomitant coronary artery disease with or without acute coronary syndromes and are in need of additional antithrombotic therapy. There are few data on the long-term clinical outcome of atrial fibrillation patients with a history of acute coronary syndrome. This is a 2-year study of atrial fibrillation patients with or without a history of acute coronary syndromes