Live rubella vectors can express native HIV envelope glycoproteins targeted by broadly neutralizing antibodies and prime the immune response to an envelope protein boost

Following HIV infection, most people make antibodies to gp120 and gp41, yet only a few make broadly neutralizing antibodies that target key antigenic sites on the envelope glycoproteins. The induction of broadly neutralizing antibodies by immunization remains a major challenge of HIV vaccine research. Difficulties include: variable protein sequence, epitopes that depend on the native conformation, glycosylation that conceals key antigenic determinants, and the assembly of Env trimers that mimic viral spikes. In addition, more potent immunogens may be needed to initiate the response of germline antibody precursors and drive B cell maturation toward antibodies with broad neutralizing activity. We have expressed HIV Env glycoproteins by incorporation into live attenuated rubella viral vectors. The rubella vaccine strain RA27/3 has demonstrated its safety and potency in millions of children. As a vector, it has elicited potent and durable immune responses in macaques to SIV Gag vaccine inserts. We now find that rubella/env vectors can stably express Env core derived glycoproteins ranging in size up to 363 amino acids from HIV clade C strain 426c. The expressed Env glycoproteins bind broadly neutralizing antibodies that target the native CD4 binding site. The vectors grew well in rhesus macaques, and they elicited a vaccine "take" in all animals, as measured by anti-rubella antibodies. By themselves, the vectors elicited modest antibody titers to the Env insert. But the combination of rubella/env prime followed by a homologous protein boost gave a strong response. Neutralizing antibodies appeared gradually after multiple vaccine doses. The vectors will be useful for testing new vaccine inserts and immunization strategies under optimized conditions of vector growth and protein expression.

Expression of complete SIV p27 Gag and HIV gp120 engineered outer domains targeted by broadly neutralizing antibodies in live rubella vectors

Infection with HIV or SIV often elicits a potent immune response to viral antigens. This includes T cells and antibodies specific for Gag and Env antigens. In contrast, when given as a vaccine, the same antigens have been weak immunogens, unable to elicit antibodies with comparable titer, durability, or neutralizing activity. We have used the live attenuated rubella vaccine strain RA27/3 as a viral vector to express HIV and SIV antigens. By mimicking an HIV infection, these vectors could elicit stronger and more durable immunity to HIV antigens. The vectors are based on the licensed rubella vaccine strain, which has demonstrated safety and potency in millions of children. One or two doses protect for life against rubella infection. The question was whether rubella vectors could similarly enhance the immunogenicity of a foreign vaccine insert. We have previously reported that rubella vectors can express small protein antigens in vitro and in vivo, where they elicit a strong immune response to the vaccine insert. The vectors have now expressed larger vaccine inserts that include epitope-rich fragments of the Gag matrix and capsid proteins (aa 41-211) or the complete p27 capsid protein with p2 (aa 136-381). These vectors have elicited a robust and durable immune response to Gag in rhesus macaques. This size range also encompasses the engineered outer domain (eOD) of HIV envelope gp120 (172 amino acids). The rubella/eOD-GT6 and GT8 vectors stably expressed glycoproteins that bind germline precursors and mature forms of VRC01-class broadly neutralizing antibodies. These vectors potentially could be used as part of a sequential immunization strategy to initiate the production of broadly neutralizing antibodies.

Harnessing the master transcriptional repressor REST to reciprocally regulate neurogenesis

Neurogenesis begins in embryonic development and continues at a reduced rate into adulthood in vertebrate species, yet the signaling cascades regulating this process remain poorly understood. Plasma membrane-initiated signaling cascades regulate neurogenesis via downstream pathways including components of the transcriptional machinery. A nuclear factor that temporally regulates neurogenesis by repressing neuronal differentiation is the repressor element 1 (RE1) silencing transcription (REST) factor. We have recently discovered a regulatory site on REST that serves as a molecular switch for neuronal differentiation. Specifically, C-terminal domain small phosphatase 1, CTDSP1, present in non-neuronal cells, maintains REST activity by dephosphorylating this site. Reciprocally, extracellular signal-regulated kinase, ERK, activated by growth factor signaling in neural progenitors, and peptidylprolyl cis/trans isomerase Pin1, decrease REST activity through phosphorylation-dependent degradation. Our findings further resolve the mechanism for temporal regulation of REST and terminal neuronal differentiation. They also provide new potential therapeutic targets to enhance neuronal regeneration after injury.

FSH: urinary and recombinant

Infertility affects approximately 10-15% of couples. To enhance the chances of conception, assisted reproductive techniques (ART) have been improved and, in the last 5 years, thousands of babies have been delivered after IVF or ICSI procedures. To obtain an appropriate and controlled ovarian hyperstimulation (COH), clinicians have introduced many drug protocols based on GnRH agonists or antagonists for pituitary down-regulation and FSH or HMG for ovarian stimulation. Currently FSH is the most common drug used for ovulation induction. It is a glycosylated protein with a molecular weight of 28000-30000Da, normally secreted by the anterior pituitary gland. The recombinant preparations of follicle stimulation hormone (r-FSH) are characterized by a higher level of purity, reduced batch to batch variability and no risk of infection. The purpose of this review was to establish the efficacy of different trials based on the use of r-FSH and urinary FSH (u-FSH) comparing published data from randomised studies on the ovulation induction for assisted reproductive techniques. Unfortunately, we did not find any paper with sufficient power to detect a clinically significant difference in pregnancy rates, however, recent meta-analysis among homogeneous trials indicates that the use of r-FSH is to be preferred to u-FSH because more oocytes were collected in cycles with better embryo quality and with more pregnancies. Recombinant FSH has a higher cost per ampoule than urinary FSH, but also a higher effectiveness. A recent cost-effectiveness analysis on follitropin alfa compared to urinary FSH-HP, using a Markov model, confirmed other previous studies that, considering the ongoing pregnancies beyond 12 weeks gestation, r-FSH is the most effective therapy for ovulation induction in ART.

Endocytosis as a mechanism for tyrosine kinase-dependent suppression of a voltage-gated potassium channel

The voltage-gated potassium channel Kv1.2 undergoes tyrosine phosphorylation-dependent suppression of its ionic current. However, little is known about the physical mechanism behind that process. We have found that the Kv1.2 alpha-subunit protein undergoes endocytosis in response to the same stimuli that evoke suppression of Kv1.2 ionic current. The process is tyrosine phosphorylation-dependent because the same tyrosine to phenylalanine mutation in the N-terminus of Kv1.2 that confers resistance to channel suppression (Y132F) also confers resistance to channel endocytosis. Overexpression of a dominant negative form of dynamin blocked stimulus-induced Kv1.2 endocytosis and also blocked suppression of Kv1.2 ionic current. These data indicate that endocytosis of Kv1.2 from the cell surface is a key mechanism for channel suppression by tyrosine kinases.

[Thrombophilic syndrome associated to phenotypic resistance to activated protein C in postmenopausal women]

AIM

Hormone replacement therapy (HRT) may reduce the risk of cardiovascular events in healthy postmenopausal women. However recent studies suggest a 2-4 fold increased risk of idiopathic venous thromboembolism (VTE) among users of HRT. Our aim was to evaluate the overall effect of HRT on hemostatic variables probably related to increased VTE risk reported in epidemiological studies.

METHODS

Therefore, 100 healthy postmenopausal women aged 45-60 years divided into 50 HRT non-users and 50 HRT users were examined. The authors assayed on the automated coagulometer ACL7000 (Instrumentation Laboratory, Milan) the procoagulant proteins: factor VIII (VIII:C) and factor VII (VII:C); the natural anticoagulant proteins: antithrombin (ATIII), protein C (PC), protein S (PS) and the resistance to anticoagulant action of activated protein C (APC-Resistance). The free tissue factor pathway inhibitor (TFPI) was measured with an ELISA method (Diagnostica Stagò; France, Roche). The in vivo coagulation and fibrinolysis activation was evaluated by the assays of prothrombin fragment 1+2 (F1+2) and plasmin- antiplasmin complexes (PAP) using ELISA techniques.

RESULTS

Increased levels of FVIII:C and FVII:C were observed in HRT users and HRT non-users women compared to controls (FVIII:C= 126+/-58%, 120+/-59% vs 85+/-15% p=0.0001; FVII: C 113+/-23%, 103+/-19% vs 90+/-16% p=0.0001). The activation peptides were significantly different compared to those found in control subjects; higher values were observed in HRT users compared to HRT non-users (F1+2=1.11+/-0.44 nM, 077+/-0.31 nM vs 0.45+/-0.35 p=0.00001; P-AP= 606+/-406 ng/ml, 514+/-205 ng/ml vs 235+/-59 p=0.0001). The ATIII and the PC were similar among the 3 different groups of subjects, but reduced levels of PS were observed in HRT users (PS 93+/-23%, 105+/-22% vs 109+/-12 p=0.0001). The mean normalized APC sensitivity ratio (APC-SR) was lower in the two populations of women as compared with that of controls (nAPC-SR 1.02+/-0.7, 1.02+/-0.8 vs 1.1+/-25 p=0.02). The values of free TFPI were reduced in HRT users compared to HRT non-users (9.1+/-1.9 ng/ml, 10.1+/-2.3 ng/ml vs 4.6+/-1.5 ng/ml p<0.0001).

CONCLUSION

HRT appears to be associated to a shift in the procoagulant-anticoagulant balance towards a procoagulant state. The changes in hemostatic system could explain the increased risk of VTE in healthy postmenopausal women during HRT, nevertheless this risk could be higher in women known to have a congenital or acquired thrombophilic state.

Risk factors for smoking abuse after heart transplantation

Patients (n = 103) were studied before heart transplantation with regard to smoking habits by means of a clinical interview, and 81 were submitted to Minnesota Multiphasic Personality Inventory (MMPI). After a mean time of 50.8 +/- 24.2 months from transplant, they were once again interviewed to ascertain their smoking habits after intervention. Nonsmokers (35 of 103) were still nonabusers. Of the remaining 68 patients who ceased smoking before heart transplant, 12 (17.6%) had returned to tobacco abuse. Dividing these 68 patients into two groups based upon the length of smoking cessation before heart transplant (less than 1 year: short term [ST] more than 1 year: long term [LT]), we noticed that the ST group showed a much greater rate of reabuse (8 of 20, 40%) than the LT group (4 of 48, 8.3%, P =.006). Analyzing six scales of MMPI, we found a statistically different score for self-control ability (scale K) in ST and LT smokers compared to nonsmokers (45.5 and 45.5 vs 51.2, P =.026), and for difficult adaptation (scale Ma) in ST compared both to LT smokers and nonsmokers (ST 57, LT 50.5, NS 47.6; P =.042 LT vs ST, P =.0005 ST vs NS). We concluded that patients who have recently decided to stop smoking and show after MMPI compilation a score of >50 for K and <50 for Ma scale have a higher risk of reabuse and need a greater effort by the transplant team to reinforce their will to stop smoking.

Tyrosine phosphorylation of Kv1.2 modulates its interaction with the actin-binding protein cortactin

Tyrosine phosphorylation evokes functional changes in a variety of ion channels. Modulation of the actin cytoskeleton also affects the function of some channels. Little is known about how these avenues of ion channel regulation may interact. We report that the potassium channel Kv1.2 associates with the actin-binding protein cortactin and that the binding is modulated by tyrosine phosphorylation. Immunocytochemical and biochemical analyses show that Kv1.2 and cortactin co-localize to the cortical actin cytoskeleton at the leading edges of the cell. Binding assays using purified recombinant proteins reveal a 19-amino acid span within the carboxyl terminus of Kv1.2 that is necessary for direct cortactin binding. Phosphorylation of specific tyrosines within the C terminus of Kv1.2 attenuates that binding. In HEK293 cells, activation of the M1 muscarinic acetylcholine receptor evokes tyrosine phosphorylation-dependent suppression of Kv1.2 ionic current. We show that M1 receptor activation also reduces the interaction of cortactin with Kv1.2 and that mutant Kv1.2 channels deficient for cortactin binding exhibit strongly attenuated ionic current. These results demonstrate a dynamic, phosphorylation-dependent interaction between Kv1.2 and the actin cytoskeleton-binding protein cortactin and suggest a role for that interaction in the regulation of Kv1.2 ionic current.

[Small ovarian cysts in postmenopause: assessment of their malignant potential with vaginal ultrasonography and tumor marker Ca125 titration]

BACKGROUND

The aim of this study was to determine the risk of malignancy in cystic ovarian tumors < 10 cm in diameter in asymptomatic postmenopausal women.

METHODS

All cystic ovarian tumors, detected by abdominal and transvaginal sonography screening, in asymptomatic postmenopausal women were evaluated with respect to size and morphology. Follow-up data were available both on patients undergoing surgery and on those who elected to be followed without operative intervention. Titration of the tumoral marker Ca125 was carried out, too.

RESULTS

Unilocular cystic tumors were detected in 32 of 352 postmenopausal patients (9%), of 45-65 years of age arrived at the "Centre for diagnosis and therapy of menopausal diseases" of the III Divisione di Ginecologia e Ostetricia della Seconda Università degli Studi di Napoli from the 1st January to the 31st December 1999. All tumors were < 10 cm in diameter and 98% were < 5 cm in diameter; just one tumor was hardly > 5 cm in diameter (5.8), 14 of these cystic ovarian tumors (49%) resolved spontaneously within 60 days while 18 (51%) persisted. Seven patients with persistent cystic ovarian tumors underwent operative tumor removal. Five of these patients had serous cystadenoma and 2 other women had cystoadenofibroma. Not even one case of ovarian carcinoma was found in this group. The remaining 11 patients with unilocular cystic ovarian tumors underwent sonography control every 3 months for one year and no one of these patients developed ovarian carcinoma. In all these patients the dosage of the tumoral marker Ca125 remained under the suspicious threshold of malignant ovaric tumor (Ca125 = 35 U/ml).

CONCLUSIONS

Unilocular cystic ovarian tumors < 5 cm in diameter in asymptomatic postmenopausal women were associated with minimal risk for ovarian cancer. In contrast, complex ovarian cysts wall abnormalities or solid areas are associated with a significant risk for malignancy. These date are important in determining therapeutic optimal strategies in these patients.

Carotid artery atherosclerotic disease assessed by flow velocity wave form analysis in hemodialyzed normotensive and hypertensive patients

Cerebrovascular accidents, often secondary to severe atherosclerotic disease, are very common in uremic patients on long-term hemodialysis. The aim of the present study is to assess asymptomatic carotid artery atherosclerotic disease (CAAD) in hemodialyzed normotensive and hypertensive patients in comparison with age-matched controls, by the use of Doppler ultrasound flow velocity wave form analysis (FVWFA), recorded from the common carotid artery. This study was performed on 47 subjects divided into four groups: 10 young and 10 middle-aged normals were considered in groups I and II, respectively, 5 young uremic normotensive, 6 young uremic hypertensive and 16 middle-aged uremic normotensive patients in groups III, IV and V, respectively. All the examined patients were nonsmokers, without diabetes or cardiopathy. The five wave form dimensions most capable of separating different degrees of atherosclerotic disease were determined on every common carotid tracing and used in a single best fit discriminant equation; the resultant discriminant score (DS) classified each carotid tracing and consequently every group's range. DS of groups I and III were not different, but significantly higher compared to the other three groups; besides DS was statistically not different in groups II, IV and V. In conclusion, FVWFA did not detect a different degree of CAAD between normotensive dialyzed patients and age-matched normals, whereas the blood pressure pharmacological control did not affect the velocity findings of advanced CAAD in young uremic hypertensive patients.

[Relation between asymmetrical hypertrophy of the interventricular septum and plasma levels of catecholamines in normotensive chronic uremic patients undergoing hemodialysis treatment]

Sympathetic-adrenergic activity has been evaluated in 23 chronic uremic, normotensive patients on regular hemodialysis, 7 of which (30.4%) with M-mode and bidimensional echocardiographic finding of asymmetric septal hypertrophy. The sympathetic function has been assessed by measuring arterial plasma norepinephrine and epinephrine levels before and after postural activation, just before and after dialysis. After dialysis, standing caused a significant increase of plasma norepinephrine levels in patients with asymmetric septal hypertrophy in comparison with patients without asymmetric septal hypertrophy and with the control non uremic group. Moreover, a significant decrease in blood pressure and a sharp heart rate increase were noted in the patients without asymmetric septal hypertrophy, whereas mean blood pressure and heart rate were unchanged in the patients with asymmetric septal hypertrophy. These results suggest that increased plasma norepinephrine concentration may have a role in the development of interventricular septal hypertrophy.