Impaired response to influenza vaccine associated with persistent memory B cell depletion in non-Hodgkin's lymphoma patients treated with rituximab-containing regimens

Influenza vaccination is generally recommended for non-Hodgkin's lymphoma (NHL) patients, but no data are available about the activity of this vaccine after treatment with rituximab-containing regimens. We evaluated the humoral response to the trivalent seasonal influenza vaccine in a group of NHL patients in complete remission for ≥6 mo (median, 29 mo) after treatment with rituximab-containing regimens (n = 31) compared with age-matched healthy subjects (n = 34). B cell populations and incidence of influenza-like illness were also evaluated. For each viral strain, the response was significantly lower in patients compared with controls and was particularly poor in patients treated with fludarabine-based regimens. In the patient group, the response to vaccination did not fulfill the immunogenic criteria based on the European Committee for Medicinal Products for Human Use requirements. Among the patients, CD27(+) memory B cells were significantly reduced, and their reduction correlated with serum IgM levels and vaccine response. Episodes of influenza-like illness were recorded only in patients. These results showed that NHL patients treated with rituximab-containing regimens have persisting perturbations of B cell compartments and Ig synthesis and may be at particular risk for infection, even in long-standing complete remission.     

Reduced tissue hardness of trabecular bone is associated with severe osteoarthritis

This study investigated whether changes in hardness of human trabecular bone are associated with osteoarthritis. Twenty femoral heads extracted from subjects without musculoskeletal diseases (subject age: 49-83 years) and twenty femoral heads extracted from osteoarthritic subjects (subject age: 42-85 years) were tested. Sixty indentations were performed along the main trabecular direction of each sample at a fixed relative distance. Two microstructures were found on the indenting locations: packs of parallel-lamellae (PL) and secondary osteons (SO). A 25gf load was applied for 15s and the Vickers Hardness (HV) was assessed. Trabecular tissue extracted from osteoarthritic subjects was found to be about 13% less hard compared to tissue extracted from non-pathologic subjects. However, tissue hardness was not significantly affected by gender or age. The SO was 10% less hard than the PL for both pathologic and non-pathologic tissues. A hardness of 34.1HV for PL and 30.8HV for SO was found for the non-pathologic tissue. For osteoarthritic tissue, the hardness was 30.2HV for PL and 27.1HV for SO. In the bone tissue extracted from osteoarthritic subjects the occurrence of indenting a SO (28%) was higher than that observed in the non-pathological tissue (15%). Osteoarthritis is associated with reduced tissue hardness and alterations in microstructure of the trabecular bone tissue. Gender does not significantly affect trabecular bone hardness either in non-pathological or osteoarthritic subjects. A similar conclusion can be drawn for age, although a larger donor sample size would be necessary to definitively exclude the existence of a slight effect.     

DNA damage in oocytes induces a switch of the quality control factor TAp63α from dimer to tetramer

TAp63α, a homolog of the p53 tumor suppressor, is a quality control factor in the female germline. Remarkably, already undamaged oocytes express high levels of the protein, suggesting that TAp63α's activity is under tight control of an inhibitory mechanism. Biochemical studies have proposed that inhibition requires the C-terminal transactivation inhibitory domain. However, the structural mechanism of TAp63α inhibition remains unknown. Here, we show that TAp63α is kept in an inactive dimeric state. We reveal that relief of inhibition leads to tetramer formation with ～20-fold higher DNA affinity. In vivo, phosphorylation-triggered tetramerization of TAp63α is not reversible by dephosphorylation. Furthermore, we show that a helix in the oligomerization domain of p63 is crucial for tetramer stabilization and competes with the transactivation domain for the same binding site. Our results demonstrate how TAp63α is inhibited by complex domain-domain interactions that provide the basis for regulating quality control in oocytes.     

Maximal oxygen consumption in relation to subordinate traits in lines of house mice selectively bred for high voluntary wheel running.

We studied relations between maximal O2 consumption (VO2 max) during forced exercise and subordinate traits associated with blood O2 transport and cellular respiration in four lines of mice selectively bred for high voluntary wheel running (S lines) and their four nonselected control (C) lines. Previously, we reported VO2 max of 59 females at three Po2 (hypoxia = 14% O2, normoxia = 21%, hyperoxia = 30%). Here, we test the hypothesis that variation in VO2 max can be explained, in part, by hemoglobin concentration and Po2 necessary to obtain 50% O2 saturation of Hb (an estimate of Hb affinity for O2) of the blood as well as citrate synthase activity and myoglobin concentration of ventricles and gastrocnemius muscle. Statistical analyses controlled for body mass, compared S and C lines, and also considered effects of the mini-muscle phenotype (present only in S lines and resulting from a Mendelian recessive allele), which reduces hindlimb muscle mass while increasing muscle mass-specific aerobic capacity. Although S lines had higher VO2 max than C, subordinate traits showed no statistical differences when the presence of the mini-muscle phenotype was controlled. However, subordinate traits did account for some of the individual variation in VO2 max. Ventricle size was a positive predictor of VO2 max at all three Po2. Blood Hb concentration was a positive predictor of VO2 max in S lines but a negative predictor in C lines, indicating that the physiological underpinnings of VO2 max have been altered by selective breeding. Mice with the mini-muscle phenotype had enlarged ventricles, with higher mass-specific citrate synthase activity and myoglobin concentration, which may account for their higher VO2 max in hypoxia.     

Monomer dimer dynamics and distribution of GPI-anchored uPAR are determined by cell surface protein assemblies

To search for functional links between glycosylphosphatidylinositol (GPI) protein monomer–oligomer exchange and membrane dynamics and confinement, we studied urokinase plasminogen activator (uPA) receptor (uPAR), a GPI receptor involved in the regulation of cell adhesion, migration, and proliferation. Using a functionally active fluorescent protein–uPAR in live cells, we analyzed the effect that extracellular matrix proteins and uPAR ligands have on uPAR dynamics and dimerization at the cell membrane. Vitronectin directs the recruitment of dimers and slows down the diffusion of the receptors at the basal membrane. The commitment to uPA–plasminogen activator inhibitor type 1–mediated endocytosis and recycling modifies uPAR diffusion and induces an exchange between uPAR monomers and dimers. This exchange is fully reversible. The data demonstrate that cell surface protein assemblies are important in regulating the dynamics and localization of uPAR at the cell membrane and the exchange of monomers and dimers. These results also provide a strong rationale for dynamic studies of GPI-anchored molecules in live cells at steady state and in the absence of cross-linker/clustering agents.     

Structural characterization of the ceruloplasmin: lactoferrin complex in solution

Ceruloplasmin is a copper protein found in vertebrate plasma, which belongs to the family of multicopper oxidases. Like transferrin of the blood plasma, lactoferrin, the iron-containing protein of human milk, saliva, tears, seminal plasma and of neutrophilic leukocytes tightly binds two ferric ions. Human lactoferrin and ceruloplasmin have been previously shown to interact both in vivo and in vitro forming a complex. Here we describe a study of the conformation of the human lactoferrin/ceruloplasmin complex in solution using small angle X-ray scattering. Our ab initio structural analysis shows that the complex has a 1:1 stoichiometry and suggests that complex formation occurs without major conformational rearrangements of either protein. Rigid-body modeling of the mutual arrangement of proteins in the complex essentially yields two families of solutions. Final discrimination is possible when integrating in the modeling process extra information translating into structural constraints on the interaction between the two partners.     

Toc64--a preprotein-receptor at the outer membrane with bipartide function

Protein translocation across membranes is assisted by translocation machineries present in the membrane targeted by the precursor proteins. Translocon subunits can be functionally divided into receptor proteins warranting the specificity of this machine and a translocation channel. At the outer envelope of chloroplasts two sets of receptor proteins regulate protein translocation facing the cytosol or acting in the intermembrane space. One, Toc64 is a receptor of the translocon at the outer envelope of chloroplasts (Toc complex) with dual function. Toc64 recognizes Hsp90 delivered precursor proteins via a cytosolic exposed domain containing three tetratrico-peptide repeat motifs and as demonstrated in here, Toc64 functions also as a major component of a complex facing the intermembrane space. The latter complex is composed of an Hsp70 localized in the intermembrane space, its interaction partner Toc12, a J-domain containing protein and the intermembrane space protein Tic22. We analyzed the intermembrane space domain of Toc64. This domain is involved in preprotein recognition and association with the Toc-complex independent of the cytosolic domain of the Toc64 receptor. Therefore, Toc64 is involved in preprotein translocation across the outer envelope at both sites of the membrane.     

Flumazenil selectively prevents the increase in alpha(4)-subunit gene expression and an associated change in GABA(A) receptor function induced by ethanol withdrawal

The actions of ethanol on gamma-aminobutyric acid type A (GABA(A)) receptors are still highly controversial issues but it appears that some of its pharmacological effects may depend on receptor subunit composition. Prolonged ethanol exposure produces tolerance and dependence and its withdrawal alters GABA(A) receptor subunit gene expression and function. Whereas benzodiazepines are clinically effective in ameliorating ethanol withdrawal symptoms, work in our laboratory showed that benzodiazepines also prevent, in vitro, some of the ethanol withdrawal-induced molecular and functional changes of the GABA(A) receptors. In the present work, we investigated the effects, on such changes, of the benzodiazepine receptor antagonist flumazenil that can positively modulate alpha(4)-containing receptors. We here report that flumazenil prevented both the ethanol withdrawal-induced up-regulation of the alpha(4)-subunit and the increase in its own modulatory action. In contrast, flumazenil did not inhibit ethanol withdrawal-induced decrease in alpha(1)- and delta-subunit expression as well as the corresponding decrease in the modulatory action on GABA(A) receptor function of both the alpha(1)-selective ligand zaleplon and the delta-containing receptor preferentially acting steroid allopregnanolone. These observations are the first molecular and functional evidence that show a selective inhibition by flumazenil of the up-regulation of alpha(4)-subunit expression elicited by ethanol withdrawal.     

Novel adeno-associated virus serotypes efficiently transduce murine photoreceptors

Severe inherited retinal diseases, such as retinitis pigmentosa and Leber congenital amaurosis, are caused by mutations in genes preferentially expressed in photoreceptors. While adeno-associated virus (AAV)-mediated gene transfer can correct retinal pigment epithelium (RPE) defects in animal models, approaches for the correction of photoreceptor-specific diseases are less efficient. We evaluated the ability of novel AAV serotypes (AAV2/7, AAV2/8, AAV2/9, AAV2rh.43, AAV2rh.64R1, and AAV2hu.29R) in combination with constitutive or photoreceptor-specific promoters to improve photoreceptor transduction, a limiting step in photoreceptor rescue. Based on a qualitative analysis, all AAV serotypes tested efficiently transduce the RPE as well as rod and cone photoreceptors after subretinal administration in mice. Interestingly, AAV2/9 efficiently transduces Müller cells. To compare photoreceptor transduction from different AAVs and promoters in both a qualitative and quantitative manner, we designed a strategy based on the use of a bicistronic construct expressing both enhanced green fluorescent protein and luciferase. We found that AAV2/8 and AAV2/7 mediate six- to eightfold higher levels of in vivo photoreceptor transduction than AAV2/5, considered so far the most efficient AAV serotype for photoreceptor targeting. In addition, following subretinal administration of AAV, the rhodopsin promoter allows significantly higher levels of photoreceptor expression than the other ubiquitous or photoreceptor-specific promoters tested. Finally, we show that AAV2/7, AAV2/8, and AAV2/9 outperform AAV2/5 following ex vivo transduction of retinal progenitor cells differentiated into photoreceptors. We conclude that AAV2/7 or AAV2/8 and the rhodopsin promoter provide the highest levels of photoreceptor transduction both in and ex vivo and that this may overcome the limitation to therapeutic success observed so far in models of inherited severe photoreceptor diseases.     

Intracellular trafficking and maturation of herpes simplex virus type 1 gB and virus egress require functional biogenesis of multivesicular bodies

The biogenesis of multivesicular bodies (MVBs) is topologically equivalent to virion budding. Hence, a number of viruses exploit the MVB pathway to build their envelope and exit from the cell. By expression of dominant negative forms of Vps4 and Vps24, two components of the MVB pathway, we observed an impairment in infectious herpes simplex virus (HSV) assembly/egress, in agreement with a recent report showing the involvement in HSV envelopment of Vps4, the MVB-specific ATPase (C. M. Crump, C. Yates, and T. Minson, J. Virol. 81:7380-7387). Furthermore, HSV infection resulted in morphological changes to MVBs. Glycoprotein B (gB), one of the most highly conserved glycoproteins across the Herpesviridae family, was sorted to MVB membranes. In cells expressing the dominant negative form of Vps4, the site of intracellular gB accumulation was altered; part of gB accumulated as an endoglycosidase H-sensitive immature form at a calreticulin-positive compartment, indicating that gB traffic was dependent on a functional MVB pathway. gB was ubiquitinated in both infected and transfected cells. Ubiquitination was in part dependent on ubiquitin lysine 63, a signal for cargo sorting to MVBs. Partial deletion of the gB cytoplasmic tail resulted in a dramatic reduction of ubiquitination, as well as of progeny virus assembly and release to the extracellular compartment. Thus, HSV envelopment/egress and gB intracellular trafficking are dependent on functional MVB biogenesis. Our data support the view that the sorting of gB to MVB membranes may represent a critical step in HSV envelopment and egress and that modified MVB membranes constitute a platform for HSV cytoplasmic envelopment or that MVB components are recruited to the site(s) of envelopment.