The tumor suppressor gene von Hippel-Lindau (VHL) is involved in the development of sporadic clear-cell renal cell carcinoma (RCC). VHL interferes with angiogenesis and also controls cell adhesion ...and invasion. Therapies that target VHL-controlled genes are currently being evaluated in RCC patients. RCC is a immunogenic tumor and treatment with interleukin-2 (IL2) or interferon (IFN)-α results in regression in some patients. We used two renal tumor cell lines (RCC6 and RCC4) carrying VHL loss-of-function mutations to investigate the role of mutant VHL in susceptibility to natural killer (NK) cell-mediated lysis. The RCC6 and RCC4 cell lines were transfected with the wild-type gene to restore the function of VHL. The presence of the gene in RCC cells downregulated hypoxia-inducible factor (HIF)-1α and subsequently decreased vascular endothelial growth factor (VEGF) production. Relative to control transfectants and parental cells, pVHL-transfected cell lines activated resting and IL2-activated NK cells less strongly, as assessed by IFNγ secretion, NK degranulation and cell lysis. NKG2A, a human leukocyte antigen (HLA)-I-specific inhibitory NK receptor, controls the lysis of tumor targets. We show that HLA-I expression in RCC-pVHL cells is stronger than that in parental and controls cells, although the expression of activating receptor NK ligands remains unchanged. Blocking NKG2A/HLA-I interactions substantially increased lysis of RCC-pVHL, but had little effect on the lysis of VHL-mutated RCC cell lines. In addition, in response to IFNα, the exponential growth of RCC-pVHL was inhibited more than that of RCC-pE cells, indicating that VHL mutations may be involved in IFNα resistance. These results indicate that a decreased expression of HLA-I molecules in mutated VHL renal tumor cells sensitizes them to NK-mediated lysis. These results suggest that combined immunotherapy with anti-angiogenic drugs may be beneficial for patients with mutated VHL.
Patients with atrial fibrillation (AF) consider the related symptoms disruptive to their quality of life (QoL). This study aimed to evaluate the impact of the control of symptomatic paroxysmal AF ...(PAF) on QoL.
Patients with symptomatic PAF were treated for 48 weeks with open-label flecainide acetate controlled release (Flec CR). Quality of life was assessed by SF-36 and Atrial Fibrillation Severity Scale scores at baseline, Week 12 (W12), W24, and W48. Of the 229 treated patients, 217 were analysed for QoL (123 with controlled and 94 with uncontrolled symptomatic PAF at inclusion). The controlled group had a similar or better QoL (SF-36) at baseline compared with a reference population (significantly better for: physical functioning, bodily pain, and physical component). The uncontrolled group had an inferior QoL (significantly worse for: role physical, general health, vitality, role emotional, social functioning, mental health, and mental component). When treated with Flec CR, the controlled group baseline QoL scores were maintained and the uncontrolled group scores were improved to a level comparable to the controlled group scores. Safety findings reflect the known clinical safety profile of flecainide acetate.
In this study, patients with uncontrolled symptomatic PAF at baseline had an inferior QoL to those with controlled symptomatic PAF. Following treatment with controlled-release flecainide acetate, their QoL improved to a level comparable to controlled patients.
Homocysteine has recently been described as an independent risk factor for osteoporotic fractures in the elderly. We prospectively followed 671 postmenopausal women belonging to the OFELY study, mean ...age 62 years, during a mean follow-up of 10 years. After adjustment for age, there was no significant relation between the plasma level of homocysteine and the subsequent risk of fracture.
Plasma homocysteine increases with age. Recent studies have described homocysteine as an independent risk factor for osteoporotic fractures in elderly. We investigated the role of plasma homocysteine in the subsequent risk of fractures in healthy ambulatory postmenopausal women.
Homocysteine was measured at baseline in 671 postmenopausal women from the OFELY cohort (mean age 62.2 +/- 9 years). Incident clinical fractures were recorded during annual follow-up and vertebral fractures were evaluated with radiographs every four years. A cox proportional hazards model based on time to first fracture was used to calculate hazard ratios for quartiles of homocysteine values.
Mean homocysteine was 10.6 +/- 3.4 mumol/l, increasing with age. After adjustment for age, homocysteine was significantly associated with physical activity, calcium intake, serum albumin and serum creatinine but not with bone turnover markers and bone mineral density. During a mean follow-up of 10 years, 183 fractures occurred among 134 women. After adjustment for age, the overall relative risk of fracture for each 1 SD increment of homocysteine was 1.03 (95%CI 0.87-1.31). Fracture risk was higher in women with homocysteine in the highest quartile without adjustment but no longer after adjustment for age.
Homocysteine is not an independent risk factor of osteoporotic fractures in healthy postmenopausal women from the OFELY cohort with a broad age range.
L’élévation des aspartates aminotransférases (ASAT) peut être associée à de nombreuses pathologies hépatiques (hépatite, stéatose hépatique, maladie des voies biliaires…), la prise de toxiques ...(notamment l’alcool), des maladies systémiques, infectieuses ou des hémopathies. L’élévation isolée des ASAT persistante chez un sujet sain asymptomatique doit pourtant faire évoquer un diagnostic permettant de limiter les examens complémentaires.
Une femme de 52 ans a été adressée en consultation de médecine interne pour suspicion de myosite devant une asthénie et des myalgies des biceps et des quadriceps. Elle n’avait pas d’antécédent significatif. Elle ne consommait pas de toxique hormis un tabagisme actif à 15 paquets-années. Elle ne prenait aucun traitement. Un bilan biologique révélait une élévation isolée des ASAT à 930UI/l (normes 5–50UI/l) soit à 18 fois la normale. La NFS, le TP et TCA étaient normaux, de même que le reste du bilan hépatique : bilirubine totale 10μmol/l (1–17μmol/l, ALAT 16UI/l (5–50UI/l, phosphatases alcalines 71UI/l(35–104UI/l et gamma-GT 13UI/l (5–36UI/l, le bilan martial était normal et les CPK à 54UI/l(20–200UI/l. Il n’y avait pas de syndrome inflammatoire biologique. L’électrophorèse des protides sériques était sans particularité, les sérologies de Lyme, CMV, hépatites A, B, C, VIH et fièvre Q étaient négatives. Le bilan immunologique retrouvait des anticorps antinucléaires au 1/160e, sans anti-ADN, ni anti-ENA. Les anticorps antimuscles lisses, mitochondries et LKM1 étaient négatifs. Le DOT myosite était négatif. Il n’y avait pas de protéinurie, et l’haptoglobine était normale. L’échographie abdominale retrouvait des angiomes hépatiques, sans hépatosplénomégalie. Le scanner abdominopelvien et l’IRM hépatique confirmaient les angiomes sans déceler de lésion suspecte. L’échographie cardiaque transthoracique ne révélait aucune anomalie. Trois mois après le début des explorations, la patiente ne décrivait plus de myalgies mais il persistait des ASAT à 12 fois la normale. L’examen clinique était normal. Le sérum de la patiente a été adressé dans un laboratoire spécialisé où il a été confirmé par électrophorèse l’existence d’un macrocomplexe ASAT. Après identification par chromatographie de filtration sur gel, ce macrocomplexe était formé par l’association d’ASAT et immunoglobulines (majoritairement des IgG, peu d’IgA). L’ASAT était de nature cytosolique, iso-enzyme normale présente dans le sérum. Cette forme de macro-ASAT n’était pas pathologique.
L’existence des macro-enzymes a largement été décrite dans la littérature 1–3. Il s’agit de complexes de haut poids moléculaire formés par la liaison entre une enzyme (ASAT, ALAT, CPK, LDH, GGT…) et une macromolécule : soit une Ig (macro-enzyme de type 1), soit une autre molécule, autopolymérisation, médicaments, lipoprotéines… (macro-enzyme de type 2). Cette forme de macro-ASAT ne signe pas de pathologie particulière, bien qu’elle puisse parfois être associée à des pathologies auto-immunes. Le type 2 est associé, à l’exception des médicaments, à une pathologie hépatobiliaire 2,3. Dans ce cas, l’existence de myalgies a pu faire penser à une pathologie musculaire.
Une élévation isolée et asymptomatique d’une enzyme en l’absence de tableau clinique associé, doit faire penser au diagnostic de macro-enzyme pour limiter des examens complémentaires inutiles et onéreux.
During intoxication of a cell, the translocation (T) domain of the diphtheria toxin helps the passage of the catalytic domain across the membrane of the endosome into the cytoplasm. We have ...investigated the behavior of the N-terminal region of the T domain during the successive steps of its interaction with membranes at acidic pH using tryptophan fluorescence, its quenching by brominated lipids, and trypsin digestion. The change in the environment of this region was monitored using mutant W281F carrying a single native tryptophan at position 206 at the tip of helix TH1. The intrinsic propensity to interact with the membrane of each helix of the N-terminus of the T domain, TH1, TH2, TH3, and TH4, was also studied using synthetic peptides. We showed the N-terminal region of the T domain was not involved in the binding of the domain to the membrane, which occurred at pH 6 mainly through hydrophobic effects. At that stage of the interaction, the N-terminal region remained strongly solvated. Further acidification eliminated repulsive electrostatic interactions between this region and the membrane, allowing its penetration into the membrane by attractive electrostatic interactions and hydrophobic effects. The peptide study indicated the nature of forces contributing to membrane penetration. Overall, the data suggested that the acidic pH found in the endosome not only triggers the formation of the molten globule state of the T domain required for membrane interaction but also governs a progressive penetration of the N-terminal part of the T domain in the membrane. We propose that these physicochemical properties are necessary for the translocation of the catalytic domain.
To assess the evolution of triglyceride (TG) levels in HIV-infected patients receiving stable potent antiretroviral therapy treated with N-3 polyunsaturated fatty acids (PUFAs), a prospective ...double-blind randomized design for a reliable assessment of TG evolution was performed. One hundred twenty-two patients with TG levels >2 g/L and ≤10 g/L after a 4-week diet (baseline TG4.5 ± 1.9 g/L) were randomized for 8 weeks to N-3 PUFAs (2 capsules containing 1 g of fish oil 3 times daily, n = 60), or placebo (1 g of paraffin oil capsules, n = 62). An 8-week open-label phase of N-3 PUFAs followed. Evaluation criteria were TG percent change at week 8, percentage of responders (normalization or ≥20% TG decrease), and safety issues. Ten patients with baseline TG levels >10 g/L were not randomized and received N-3 PUFAs as open treatment. The difference (PUFA - placebo) in TG percent change at week 8 was −24.6% (range−40.9% to −8.4%; P = 0.0033), the median was −25.5% in the PUFA group versus 1% in the placebo group, and mean TG levels at week 8 were 3.4 ± 1.8 g/L and 4.8 ± 3.1 g/L, respectively. TG levels were normalized in 22.4% (PUFA) versus 6.5% (placebo) of patients (P = 0.013) with a ≥20% reduction in 58.6% (PUFA) versus 33.9% (placebo) of patients (P = 0.007). Under the open-label phase of N-3 PUFAs, the decrease in TG levels was sustained at week 16 for patients in the PUFA group (mean TG3.4 ± 1.7 g/L), whereas a 21.2% decrease in TG levels occurred for patients in the placebo group (mean TG3.3 ± 1.4 g/L). No significant differences were observed between groups in the occurrence of adverse events. The median TG change at week 8 was −43.6% (rangeQ1-Q3; 95% CI−66.5% to −4.6%) for patients with baseline TG levels >10 g/L. The difference in mean total cholesterol between groups (PUFA - placebo) at week 8 was −8.5% (P = 0.0117). This study demonstrated the efficacy of PUFAs to lower elevated TG levels in treated HIV-infected hypertriglyceridemic patients. N-3 PUFAs have a good safety profile.
We describe the creation of cell adhesion mediated by cell surface engineering. The Flt3-ligand was fused to a membrane anchor made of the diphtheria toxin translocation domain. The fusion protein ...was attached to the surface of a cell by an acid pulse. Contact with another cell expressing the receptor Flt3 lead to its activation. This activity involved direct cell–cell contact. A mean force of 20
nN was needed to separate functionalized cells after 5
min of contact. Overall, we showed that it is possible to promote specific cell–cell adhesion by attaching protein ligands at the surface of cells.
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