Soluble HIV-1 Env trimers in adjuvant elicit potent and diverse functional B cell responses in primates

Broadly neutralizing antibodies (bNAbs) against the HIV-1 envelope glycoproteins (Envs) have proven difficult to elicit by immunization. Therefore, to identify effective Env neutralization targets, efforts are underway to define the specificities of bNAbs in chronically infected individuals. For a prophylactic vaccine, it is equally important to define the immunogenic properties of the heavily glycosylated Env in healthy primates devoid of confounding HIV-induced pathogenic factors. We used rhesus macaques to investigate the magnitude and kinetics of B cell responses stimulated by Env trimers in adjuvant. Robust Env-specific memory B cell responses and high titers of circulating antibodies developed after trimer inoculation. Subsequent immunizations resulted in significant expansion of Env-specific IgG-producing plasma cell populations and circulating Abs that displayed increasing avidity and neutralization capacity. The neutralizing activity elicited with the regimen used was, in most aspects, superior to that elicited by a regimen based on monomeric Env immunization in humans. Despite the potency and breadth of the trimer-elicited response, protection against heterologous rectal simian-HIV (SHIV) challenge was modest, illustrating the challenge of eliciting sufficient titers of cross-reactive protective NAbs in mucosal sites. These data provide important information for the design and evaluation of vaccines aimed at stimulating protective HIV-1 immune responses in humans

Xeno-Free and Defined Human Embryonic Stem Cell-Derived Retinal Pigment Epithelial Cells Functionally Integrate in a Large-Eyed Preclinical Model

SummaryHuman embryonic stem cell (hESC)-derived retinal pigment epithelial (RPE) cells could replace lost tissue in geographic atrophy (GA) but efficacy has yet to be demonstrated in a large-eyed model. Also, production of hESC-RPE has not yet been achieved in a xeno-free and defined manner, which is critical for clinical compliance and reduced immunogenicity. Here we describe an effective differentiation methodology using human laminin-521 matrix with xeno-free and defined medium. Differentiated cells exhibited characteristics of native RPE including morphology, pigmentation, marker expression, monolayer integrity, and polarization together with phagocytic activity. Furthermore, we established a large-eyed GA model that allowed in vivo imaging of hESC-RPE and host retina. Cells transplanted in suspension showed long-term integration and formed polarized monolayers exhibiting phagocytic and photoreceptor rescue capacity. We have developed a xeno-free and defined hESC-RPE differentiation method and present evidence of functional integration of clinically compliant hESC-RPE in a large-eyed disease model

Transforming Growth Factor-β3 Regulates Adipocyte Number in Subcutaneous White Adipose Tissue.

White adipose tissue (WAT) mass is determined by adipocyte size and number. While adipocytes are continuously turned over, the mechanisms controlling fat cell number in WAT upon weight changes are unclear. Herein, prospective studies of human subcutaneous WAT demonstrate that weight gain increases both adipocyte size and number, but the latter remains unaltered after weight loss. Transcriptome analyses associate changes in adipocyte number with the expression of 79 genes. This gene set is enriched for growth factors, out of which one, transforming growth factor-β3 (TGFβ3), stimulates adipocyte progenitor proliferation, resulting in a higher number of cells undergoing differentiation in vitro. The relevance of these observations was corroborated in vivo where Tgfb3+/- mice, in comparison with wild-type littermates, display lower subcutaneous adipocyte progenitor proliferation, WAT hypertrophy, and glucose intolerance. TGFβ3 is therefore a regulator of subcutaneous adipocyte number and may link WAT morphology to glucose metabolism

ETUDE DE L'ENGAGEMENT DES PRECURSEURS HEMATOPOIETIQUES ET DE LEUR DIFFERENCIATION EN LYMPHOCYTES T ET NK

LES CELLULES QUI COMPOSENT LE SYSTEME HEMATOPOIETIQUE PRESENTENT LA PARTICULARITE D'ETRE EN CONSTANT RENOUVELLEMENT A PARTIR DE CELLULES SOUCHES HEMATOPOIETIQUES (CSH) PENDANT TOUTE LA VIE D'UN INDIVIDU. L'ETUDE DE CE SYSTEME PRESENTE DONC UN INTERET MAJEUR POUR LA COMPREHENSION DES MECANISMES CELLULAIRES ET MOLECULAIRES REGISSANT L'ENGAGEMENT DES PRECURSEURS HEMATOPOIETIQUES DANS LES DIVERSES VOIES DE DIFFERENCIATIONS. DE FAIT, LA CONNAISSANCE DE LA HIERARCHIE AINSI QUE DES PRECURSEURS INTERMEDIAIRES ENTRE LA CELLULE SOUCHE ET LES CELLULES DIFFERENCIEES SONT DES PRE-REQUIS POUR CETTE ETUDE. DANS L'OBJECTIF DE MIEUX COMPRENDRE CES MECANISMES, NOUS AVONS FOCALISE NOS EFFORTS A LA CARACTERISATION DES PRECURSEURS DES LYMPHOCYTES T ET NK. NOUS AVONS MONTRE QU'UNE FOIS DANS LE FOIE FTAL, LES PRECURSEURS T PROLIFERENT AVANT DE MIGRER PROBABLEMENT VERS LE THYMUS POUR Y SUBIR LES ULTIMES ETAPES DE MATURATION. EN PARALLELE, NOUS AVONS OBSERVE QU'APRES LE STADE 12 DPC, LE THYMUS EST COLONISE PAR NOMBRE CROISSANT DE PRECURSEURS NETTEMENT PLUS EFFICACES DANS LA GENERATION DE LYMPHOCYTES T QUE LES PREMIERS PROGENITEURS AYANT COLONISE L'EBAUCHE THYMIQUE. CETTE CONCLUSION, NOUS A CONDUIT A ENVISAGER UN SCENARIO SELON LEQUEL LE PROGRAMME DE DIFFERENCIATION VERS LA LIGNEE T SERAIT INITIE AU NIVEAU DU FOIE FTAL, AVANT L'ARRIVEE DE CES PRECURSEURS T DANS LE THYMUS. DE FAIT, L'ANALYSE DU POTENTIEL DE DIFFERENCIATION IN VITRO DE DIFFERENTES POPULATIONS TRIEES DE CELLULES DU FOIE FTAL AU STADE 15 DPC NOUS A PERMIS DE MONTRER QUE LA MAJORITE DES PRECURSEURS T PRESENT DANS CET ORGANE ETAIENT DES PRECURSEURS BIPOTENT RESTREINTS AUX LIGNEES T ET NK. ENFIN, NOUS AVONS ETENDU NOTRE ETUDE A LA CARACTERISATION DES PRECURSEURS DE CELLULES NK AU NIVEAU DE LA MOELLE OSSEUSE ADULTE, OU NOUS AVONS IDENTIFIE UNE POPULATION DE PROGENITEURS ENGAGES VERS LA VOIE DE DIFFERENCIATION NK.PARIS-BIUSJ-Thèses (751052125) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Role of Interferon Regulatory Factor 3 in Type I Interferon Responses in Rotavirus-Infected Dendritic Cells and Fibroblasts

The main pathway for the induction of type I interferons (IFN) by viruses is through the recognition of viral RNA by cytosolic receptors and the subsequent activation of interferon regulatory factor 3 (IRF-3), which drives IFN-α/β transcription. In addition to their role in inducing an antiviral state, type I IFN also play a role in modulating adaptive immune responses, in part via their effects on dendritic cells (DCs). Many viruses have evolved mechanisms to interfere with type I IFN induction, and one recently reported strategy for achieving this is by targeting IRF-3 for degradation, as shown for rotavirus nonstructural protein 1 (NSP1). It was therefore of interest to investigate whether rotavirus-exposed DCs would produce type I IFN and/or mature in response to the virus. Our results demonstrate that IRF-3 was rapidly degraded in rotavirus-infected mouse embryonic fibroblasts (MEFs) and type I IFN was not detected in these cultures. In contrast, rotavirus induced type I IFN production in myeloid DCs (mDCs), resulting in their activation. Type I IFN induction in response to rotavirus was reduced in mDCs from IRF-3(−/−) mice, indicating that IRF-3 was important for mediating the response. Exposure of mDCs to UV-treated rotavirus induced significantly higher type I IFN levels, suggesting that rotavirus-encoded functions also antagonized the response in DCs. However, in contrast to MEFs, this action was not sufficient to completely abrogate type I IFN induction, consistent with a role for DCs as sentinels for virus infection

Early Alpha/Beta Interferon Production by Myeloid Dendritic Cells in Response to UV-Inactivated Virus Requires Viral Entry and Interferon Regulatory Factor 3 but Not MyD88

Alpha/beta interferons (IFN-α/β) are key mediators of innate immunity and important modulators of adaptive immunity. The mechanisms by which IFN-α/β are induced are becoming increasingly well understood. Recent studies showed that Toll-like receptors 7 and 8 expressed by plasmacytoid dendritic cells (pDCs) mediate the endosomal recognition of incoming viral RNA genomes, a process which requires myeloid differentiation factor 88 (MyD88). Here we investigate the requirements for virus-induced IFN-α/β production in cultures of bone marrow-derived murine myeloid DCs (mDCs). Using recombinant Semliki Forest virus blocked at different steps in the viral life cycle, we show that replication-defective virus induced IFN-α/β in mDCs while fusion-defective virus did not induce IFN-α/β. The response to replication-defective virus was largely intact in MyD88(−/−) mDC cultures but was severely reduced in mDC cultures from mice lacking IFN regulatory factor 3. Our observations suggest that mDCs respond to incoming virus via a pathway that differs from the fusion-independent, MyD88-mediated endosomal pathway described for the induction of IFN-α/β in pDCs. We propose that events during or downstream of viral fusion, but prior to replication, can activate IFN-α/β in mDCs. Thus, mDCs may contribute to the antiviral response activated by the immune system at early time points after infection

Single-cell analysis of human ovarian cortex identifies distinct cell populations but no oogonial stem cells

The human ovary orchestrates sex hormone production and undergoes monthly structural changes to release mature oocytes. The outer lining of the ovary (cortex) has a key role in defining fertility in women as it harbors the ovarian reserve. It has been postulated that putative oogonial stem cells exist in the ovarian cortex and that these can be captured by DDX4 antibody isolation. Here, we report single-cell transcriptomes and cell surface antigen profiles of over 24,000 cells from high quality ovarian cortex samples from 21 patients. Our data identify transcriptional profiles of six main cell types; oocytes, granulosa cells, immune cells, endothelial cells, perivascular cells, and stromal cells. Cells captured by DDX4 antibody are perivascular cells, not oogonial stem cells. Our data do not support the existence of germline stem cells in adult human ovaries, thereby reinforcing the dogma of a limited ovarian reserve. The outer lining or cortex of the human ovary determines fertility and has been postulated to contain oogonial stem cells. Here, the authors generate a single-cell map of the adult human ovarian cortex and show that DDX4 labels perivascular cells but no oogonial stem cells.Peer reviewe

Biosafety during a pandemic: shared resource laboratories rise to the challenge

Biosafety has always been an important aspect of daily work in any research institution, particularly for cytometry Shared Resources Laboratories (SRLs). SRLs are common-use spaces that facilitate the sharing of knowledge, expertise, and ideas. This shar