Proprotein convertase substilisin/kexin type 9 antagonism reduces low-density lipoprotein cholesterol in statin-treated hypercholesterolemic nonhuman primates

Proprotein convertase substilisin/kexin type 9 (PCSK9) promotes the degradation of low-density lipoprotein (LDL) receptor (LDLR) and thereby increases serum LDL-cholesterol (LDL-C). We have developed a humanized monoclonal antibody that recognizes the LDLR binding domain of PCSK9. This antibody, J16, and its precursor mouse antibody, J10, potently inhibit PCSK9 binding to the LDLR extracellular domain and PCSK9-mediated down-regulation of LDLR in vitro. In vivo, J10 effectively reduces serum cholesterol in C57BL/6 mice fed normal chow. J16 reduces LDL-C in healthy and diet-induced hypercholesterolemic cynomologous monkeys, but does not significantly affect high-density lipoprotein-cholesterol. Furthermore, J16 greatly lowered LDL-C in hypercholesterolemic monkeys treated with the HMG-CoA reductase inhibitor simvastatin. Our data demonstrate that anti-PCSK9 antibody is a promising LDL-C-lowering agent that is both efficacious and potentially additive to current therapies.     

Inhibition of pathologic retinal neovascularization by alpha-defensins

Proliferative retinopathies, such as those complicating prematurity and diabetes, are major causes of blindness. A prominent feature of these retinopathies is excessive neovascularization, which is orchestrated by the hypoxia-induced vascular endothelial growth factor (VEGF) stimulating endothelial cells and the integrin-mediated adhesive interactions of endothelial cells with extracellular matrix components such as fibronectin (FN). Recently, we demonstrated that alpha-defensins interfere with alpha5beta1-FN interactions and dependent endothelial cell functions. Here, alpha-defensins were studied in hypoxia-induced proliferative retinopathy. In vitro, alpha-defensins specifically inhibited alpha5beta1-integrin-dependent migration of bovine retinal endothelial cells (BRECs) to FN, attenuated the VEGF-stimulated increase in endothelial permeability, and blocked BREC proliferation and capillary sprout formation in 3-dimensional fibrin-matrices. An up-regulation of beta1-integrin and FN was observed in the retinal vessels in the mouse model of hypoxia-induced retinal angiogenesis. Systemic and local administration of alpha-defensins reduced retinal neovascularization by 45% and 60%, respectively, and this effect was comparable to the inhibitory effect of alpha5beta1-blocking antibody. alpha-Defensins were detected in human diabetic retinas associated with normal retinal vessels but were absent from proliferative lesions. Together, these data show that alpha-defensins inhibit pathologic retinal neovascularization in vivo and may provide a clinically efficient strategy against proliferative retinopathies.     

CD1d-unrestricted NKT cells are endowed with a hybrid function far superior than that of iNKT cells

Invariant natural killer T (iNKT) cells to date represent the best example of cells known to have a hybrid function, representing both innate and adaptive immunity. Shared phenotypic similarities with NK cells together with a rapid response to a cytokine stimulus and a productive TCR engagement are the features that underline the hybrid nature of iNKT cells. Using these criteria, we provide molecular and functional evidence demonstrating that CD1d-independent (CD1d^ind) NKT cells, a population of CD1d-unrestricted NKT cells, are endowed with a hybrid function far superior to that of iNKT cells: (i) an extensive shared program with NK cells, (ii) a closer Euclidian distance with NK cells, and (iii) the ability to respond to innate stimuli (Poly:IC) with cytotoxic potential in the same manner as NK cells identify a hybrid feature in CD1d^indNKT cells that truly fulfills the dual function of an NK and a T cell. Our finding that CD1d^indNKT cells are programmed to act like NK cells in response to innate signals while being capable of adaptive responses is unprecedented, and thus might reemphasize CD1d-unrestricted NKT cells as a subset of lymphocytes that could affect biological processes of antimicrobial and tumor immunity in a unique way.Natural killer T (NKT) cells are increasingly regarded as cells endowed with a hybrid function between an NK cell and a T cell (1, 2). The current classification of NKT cells places them into three categories: type I, type II, and NKT-like cells (1). Type I comprises invariant NKT (iNKT) cells that recognize the glycolipid α-galactosylceramide (α-GalCer) loaded into the MHC class I molecule, CD1d, and contain an invariant TCR repertoire of Vα14-Jα18 (3–5). Type II NKT cells are also CD1d dependent but do not respond to α-GalCer in the same way as iNKT cells do (6, 7). NKT-like cells encompass all other NKT cells and are CD1d independent (CD1d^ind) (8); they are by far the most heterogeneous and the least characterized.Recent studies have increasingly shown a shared expression of NK cell-related receptors on other effector cells. CD8⁺ T cells are known to up-regulate NK markers, such as NK1.1, and can even respond quickly like NK cells (9). Other work has described NKT cells that express NKp46 (10), a marker selectively associated with conventional NK cells and NK22 cells in the gut (11). Moreover, γδ T cells have been shown to express NK markers and display an innate-like response (12). Collectively, these reports converge to raise the following key questions. What qualifies as an NKT cell? Do the cells need to express only NK1.1 and CD3 to be eligible for NKT nomenclature? With the continuous development of both NK and T-cell fields, the simplistic definition that NKT cells are subsets of T cells that express the NK1.1 marker is becoming increasingly misleading and even inaccurate. For instance, NK1.1 complex is expressed in the BALB/c strain but there are allelic divergences with the polymorphism leading to the PK136 antibody not reacting to the BALB/c NK.1.1 (NKrp1) complex (13). This definition is also limited in the C57BL/6 strain because of the discovery of NK1.1⁻CD1d⁺ NKT cells (14). Although phenotypic similarities can be misleading, the criteria that best describes an NKT cell is the ability to perform with a hybrid function between an NK cell and a T cell (2).Nonetheless, the concept of hybrid function is also an elusive notion allowing for a gradient of functions. A number of works refer to an NKT hybrid function as the ability of a T cell with phenotypic similarities to NK cells to perform with innate-like response. The best example of cells endowed with a hybrid NKT cell function are thought to be iNKT cells (2). In this study, we provide molecular and functional evidence demonstrating that CD1d^indNKT cells—a population of MHC-unrestricted T cells—are endowed with a hybrid function that associates them to the NK cell lineage in a manner far superior to the known link between NK and iNKT cells. An extensive shared program with NK cells, a similarity in the gene expression profile with NK cells, and their ability to respond (like NK cells) not only to cytokine signals (IL-12 plus IL-18) but also to innate stimuli [in vivo treatment with Poly:IC (Fisher)] with massive production of key effector players of the cytotoxic pathway collectively identify a hybrid feature in CD1d^indNKT cells that uniquely fulfills the function of an NK cell and a T cell.     

Complexity and Distribution of Drivers in Relation to Duration of Persistent Atrial Fibrillation

Background

The underlying mechanisms sustaining human persistent atrial fibrillation (PsAF) is poorly understood.

Psoas abscess: An unusual manifestation of Q fever

Q fever may lead to serious complications in chronically infected patients. We report two cases of psoas abscess due to Coxiella burnetii associated with lumbar osteomyelitis secondary to an aortic aneurysmal infection. Diagnosis was based on serology, and PCR detected C. burnetii DNA in an abscess sample.     

Clinical study of 40 cases of incontinentia pigmenti

OBJECTIVE: To analyze the distribution of manifestations in a pediatric cohort and define guidelines for follow-up of incontinentia pigmenti (IP). DESIGN: Retrospective study of 47 children referred to the Department of Pediatric Dermatology with a diagnosis of IP between 1986 and 1999. SETTING: The private or institutional practice of participating dermatologists and pediatricians. MAIN OUTCOME MEASURES: Evaluation of IP clinical diagnosis using the Landy and Donnai criteria. RESULTS: Because hyperpigmentation following the Blaschko lines may be observed in several pigmented disorders, 7 patients were found misdiagnosed. During the neonatal period, erythema, vesicles, and hyperkeratotic le sions were rarely absent in the patients with IP. Ocular and neurological abnormalities were frequent (20% and 30%, respectively) but rarely severe (8% and 7.5%, respectively). CONCLUSIONS: Clinical diagnosis is the first main step for a correct phenotype/genotype correlation, which remains indispensable to better understand the pathological mechanisms of IP and develop new therapies. In doubtful cases, molecular analysis is helpful but characteristic histological features must be added as major criteria for IP diagnosis. Multidisciplinary follow-up is needed, particularly during the first year of life, to detect possible ophthalmologic and neurological complications. Neuroimaging ought to be performed in the case of abnormal neurological examination results or when vascular retinopathy is detected.     

High molecular response rate of polycythemia vera patients treated with pegylated interferon alpha-2a

V617F JAK2 mutation is a reliable molecular marker of polycythemia vera (PV), potentially useful to monitor the effect of treatments in this disease. In a phase 2 study of pegylated (peg) IFN-alpha-2a in PV, we performed prospective sequential quantitative evaluation of the percentage of mutated JAK2 allele (%V617F) by real-time polymerase chain reaction (PCR). The %V617F decreased in 24 (89%) of 27 treated patients, from a mean of 49% to a mean of 27% (mean decrease of 44%; P < .001), and no evidence for a plateau was observed. In one patient, mutant JAK2 was no longer detectable after 12 months. In 3 patients homozygous for the mutation, reappearance of 50% of wild-type allele was observed during treatment. The results seem to confirm the hypothesis that IFN-alpha preferentially targets the malignant clone in PV and show that %V617F assessment using a quantitative method may provide the first tool to monitor minimal residual disease in PV. This trial was registered at www.clinicaltrials.gov as #NCT00241241.     

Hemochromatosis associated with cholelithiasis as a cause of hydrops fetalis and stillbirth: Prenatal diagnosis

Prenatal diagnosis of neonatal hemochromatosis (NH) is usually raised in front of fetal hepatomegaly and heterogeneous liver architecture. We describe a novel sonographic feature that may be associated with NH. Ultrasound demonstrated reticulonodular liver and distended gallbladder with multiple gallstones in a hydropic fetus. These abnormalities were confirmed to be consistent with NH after correlation with autopsy findings. This case report highlights the value of cholelithiasis in clinical suspicion of NH and the importance to consider this sonographic feature when the liver has abnormal texture.