Lack of an immune response against the tetracycline-dependent transactivator correlates with long-term doxycycline-regulated transgene expression in nonhuman primates after intramuscular injection of recombinant adeno-associated virus

We previously documented persistent regulation of erythropoietin (Epo) secretion in mice after a single intramuscular (i.m.) injection of a recombinant adeno-associated virus (rAAV) vector harboring both the tetracycline-dependent transactivator (rtTA) and the Epo cDNA (D. Bohl, A. Salvetti, P. Moullier, and J. M. Heard, Blood 92:1512-1517, 1998). Using the same vector harboring the cynomolgus macaque Epo cDNA instead, the present study evaluated the ability of the tetracycline-regulatable (tetR) system to establish long-term transgene regulation in nonhuman primates. The vector was administered i.m., after which 5-day induction pulses were performed monthly for up to 13 months by using doxycycline (DOX), a tetracycline analog. We show that initial inductions were successful in all individuals and that there was a tight regulation and a rapid deinduction pattern upon DOX withdrawal. For one macaque, regulation of Epo secretion was maintained during the entire experimental period; for the five remaining macaques, secreted Epo became indistinguishable from endogenous Epo upon repeated DOX inductions. We investigated the mechanism involved and showed that, except in the animal in which secretion persisted, delayed humoral and cellular immune responses were directed against the rtTA transactivator protein associated with the reduction of vector DNA in transduced muscles. This study provides some evidence that, when the immune system is not mobilized against the rtTA transactivator, the tetR-regulatable system is able to support long-term transgene regulation in the context of an rAAV in nonhuman primates. In addition, our results suggest potential improvements for vector design.     

Proliferative generation of mammalian auditory hair cells in culture

Hair cell (HC) and supporting cell (SC) productions are completed during early embryonic development of the mammalian cochlea. This study shows that acutely dissociated cells from the newborn rat organ of Corti, developed into so-called otospheres consisting of 98% nestin (+) cells when plated on a non-adherent substratum in the presence of either epidermal growth factor (EGF) or fibroblast growth factor (FGF2). Within cultured otospheres, nestin (+) cells were shown to express EGF receptor (EGFR) and FGFR2 and rapidly give rise to newly formed myosin VIIA (+) HCs and p27(KIP1) (+) SCs. Myosin VIIA (+) HCs had incorporated bromodeoxyuridine (BrdU) demonstrating that they were generated by a mitotic process. Ultrastructural studies confirmed that HCs had differentiated within the otosphere, as defined by the presence of both cuticular plates and stereocilia. This work raises the hypothesis that nestin (+) cells might be a source of newly generated HCs and SCs in the injured postnatal organ of Corti.     

Extraction and quantitative analysis of the blue-green pigment “marennine” synthesized by the diatom Haslea ostrearia

This study reports further information on mareninne, awater-soluble blue-green pigment synthesized by the diatom Hasleaostrearia, which is essential to the greening of maturing oysters inFrench production areas. The extraction process is reported, as well aspreliminary characterization of a partially purified marennine extract,including quantitative spectrophotometric analysis of intracellular pigment. Amean specific extinction coefficient, E ^1% _1cm = 17.2 at 669 nm, is proposed. Results forquantitative determination of marennine accumulated in cells during batchcultures are presented, and their importance for pigment production isconsidered in relation to potential industrial applications.     

Regulation of the interleukin-1 receptor antagonist in THP-1 cells by ligands of the peroxisome proliferator-activated receptor gamma

Monocytes/macrophages (Mphi) play a pivotal role in the persistence of chronic inflammation and local tissue destruction in diseases such as rheumatoid arthritis and atherosclerosis. The production by Mphi of cytokines, chemokines, metalloproteinases and their inhibitors is an essential component in this process, which is tightly regulated by multiple factors. The peroxisome proliferator-activated receptors (PPARs) were shown to be involved in modulating inflammation. PPARgamma is activated by a wide variety of ligands such as fatty acids, the anti-diabetic thiazolidinediones (TZDs), and also by certain prostaglandins of which 15-deoxy-Delta(12,14)-PGJ2 (PGJ2). High concentrations of PPARgamma ligands were shown to have anti-inflammatory activities by inhibiting the secretion of interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor alpha (TNFalpha) by stimulated monocytes.The aim of this study was to determine whether PGJ2 and TZDs would also exert an immunomodulatory action through the up-regulation of anti-inflammatory cytokines such as the IL-1 receptor antagonist (IL-1Ra). THP-1 monocytic cells were stimulated with PMA, thereby enhancing the secretion of IL-1, IL-6, TNFalpha, IL-1Ra and metalloproteinases. Addition of PGJ2 had an inhibitory effect on IL-1, IL-6 and TNFalpha secretion, while increasing IL-1Ra production. In contrast, the bona fide PPARgamma ligands (TZDs; rosiglitazone, pioglitazone and troglitazone) barely inhibited proinflammatory cytokines, but strongly enhanced the production of IL-1Ra from PMA-stimulated THP-1 cells. Unstimulated cells did not respond to TZDs in terms of IL-1Ra production, suggesting that in order to be effective, PPAR ligands depend on PMA signalling. Basal levels of PPARgamma are barely detectable in unstimulated THP-1 cells, while stimulation with PMA up-regulates its expression, suggesting that higher levels of PPARgamma expression are necessary for receptor ligand effects to occur. In conclusion, we demonstrate for the first time that TZDs may exert an anti-inflammatory activity by inducing the production of the IL-1Ra.     

Inheritable forms of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) arises from parafollicular or C cells of the thyroid that produce calcitonin. It accounts for 5-10% of all thyroid cancers. Hereditary MTC represents 20-30% of all MTCs. It can be transmitted with an autosomal dominant pattern, either as a single entity, familial MTC, or it can arise as part of a multiple endocrine neoplasia (MEN) syndrome type 2A or 2B. The identification of hereditary MTC has been facilitated in recent years by the direct analysis of the ret proto-oncogene.     

Increased myocardial expression of RAMP1 and RAMP3 in rats with chronic heart failure

Calcitonin gene-related peptide (CGRP) and adrenomedullin (ADM) are potent vasodilators in humans and improved myocardial ischemia is observed after CGRP administration. Receptors for CGRP and ADM were already identified in heart. Receptor activity-modifying proteins (RAMPs) determine the ligand specificity of the calcitonin receptor-like receptor (CRLR); co-expression of RAMP1 and CRLR results in a CGRP receptor, whereas the association of RAMP2 or RAMP3 with CRLR gives an ADM receptor. As CGRP and ADM may play a beneficial role in heart failure, we investigated whether the CGRP and ADM receptors are upregulated in chronic heart failure. We have used semi-quantitative RT-PCR and Western-blot analysis to detect and quantify the mRNA and the protein of RAMP1 and RAMP3 in both atria and ventricles of failing hearts 6 months after aortic banding in rats. Our results showed for the first time an up-regulation of RAMP1 and RAMP3 mRNAs and proteins in this model of cardiac failure. No change was observed in mRNAs coding for CRLR, RAMP2, RDC1 (canine orphan receptor), and ADM. The present results suggested after congestive heart failure in adult rats, an up-regulation of the CGRP receptor (by an increase in RAMP1 that is associated with CRLR) in atria and ventricles and of ADM receptor (by increased RAMP3 expression that is associated with CRLR) in atria. These findings support a functional role for CGRP and ADM receptors to compensate the chronic heart failure in rats.