Blockade of CD40-CD154 Costimulatory Pathway Promotes Survival of Allogeneic Corneal Transplants

purpose. To determine the effect of systemic anti-CD154 monoclonal antibody on the survival of orthotopic murine corneal transplants. methods. BALB/c mice were used as recipients of syngeneic, multiple minor histocompatability (H)–disparate, or major histocompatibility complex MHC-mismatched corneal transplants. Recipient beds were either avascular (normal risk) or neovascularized (high risk). Mice were randomized to receive either anti-CD154 antibody or control immunoglobulin by intraperitoneal injection at surgery and once weekly after surgery. After orthotopic corneal transplantation, all grafts were evaluated for signs of rejection by slit lamp biomicroscopy over 8 weeks. The high-risk transplants were continuously observed until week 18 after the therapy was discontinued at week 8. Allospecific delayed-type hypersensitivity (DTH) was evaluated after transplantation in high-risk graft recipients. Frequency of interferon (IFN)-γ–secreting T cells in the hosts was measured by enzyme-linked immunospot (ELISPOT) assay. results. In normal-risk transplantation, the 8-week survival rate improved from 25% in control mice to 88% in anti-CD154–treated hosts of minor H–disparate grafts (P = 0.0087) and from 78% in control mice to 100% in anti-CD154–treated recipients of MHC-mismatched transplants (P = 0.177). Of particular significance, in high-risk transplantation, anti-CD154 therapy dramatically enhanced the survival of both minor H– and MHC-disparate corneal transplants to 100% (P = 0.0001) and 92% (P = 0.0002), respectively. In addition, the anti-CD154–treated mice did not exhibit allospecific immunity. However, termination of anti-CD154 led to some loss in graft survival, especially among high-risk minor H–disparate grafts. The frequency of IFN-γ–producing T cells was significantly reduced in anti-CD154–treated hosts. conclusions. Continuous suppression of the CD40-CD154 costimulatory pathway promotes the acceptance of corneal transplants, regardless of the degree of allodisparity or preoperative risk. The beneficial effect of anti-CD154 treatment may be due in part to inhibition of Th1-mediated responses

Nuclear distribution of the orphan nuclear receptor COUP-TFI in P19 EC cells defines a new subnuclear domain

Poste

Partial activation of neonatal CD11c+ dendritic cells and induction of adult-like CD8+ cytotoxic T cell responses by synthetic microspheres

Neonatal cytotoxic T cell responses have only been elicited to date with immunogens or delivery systems inducing potent direct APC activation. To define the minimal activation requirements for the induction of neonatal CD8(+) cytotoxic responses, we used synthetic microspheres (MS) coated with a single CD8(+) T cell peptide from lymphocytic choriomeningitis virus (LCMV) or HIV-1. Unexpectedly, a single injection of peptide-conjugated MS without added adjuvant induced CD4-dependent Ag-specific neonatal murine cytotoxic responses with adult-like CTL precursor frequency, avidity for Ag, and frequency of IFN-gamma-secreting CD8(+) splenocytes. Neonatal CD8(+) T cell responses to MS-LCMV were elicited within 2 wk of a single immunization and, upon challenge, provided similar protection from viral replication as adult CTLs, demonstrating their in vivo competence. As previously reported, peptide-coated MS elicited no detectable activation of adult CD11c(+) dendritic cells (DC). In contrast, CTL responses were associated with a partial activation of neonatal CD11c(+) DC, reflected by the up-regulation of CD80 and CD86 expression but no concurrent changes in MHC class II or CD40 expression. However, this partial activation of neonatal DC was not sufficient to circumvent the requirement for CD4(+) T cell help. The effective induction of neonatal CD8(+) T cell responses by this minimal Ag delivery system demonstrates that neonatal CD11c(+) DC may mature sufficiently to stimulate naive CD8(+) neonatal T cells, even in the absence of strong maturation signals

Enhanced liver gene transfer and evasion of preexisting humoral immunity with exosome-enveloped AAV vectors

Results from clinical trials of liver gene transfer for hemophilia demonstrate the potential of the adeno-associated virus (AAV) vector platform. However, to achieve therapeutic transgene expression, in some cases high vector doses are required, which are associated with a higher risk of triggering anti-capsid cytotoxic T-cell responses. Additionally, anti-AAV preexisting immunity can prevent liver transduction even at low neutralizing antibody (NAb) titers. Here, we describe the use of exosome-associated AAV (exo-AAV) vectors as a robust liver gene delivery system that allows the therapeutic vector dose to be decreased while protecting from preexisting humoral immunity to the capsid. The in vivo efficiency of liver targeting of standard AAV8 or AAV5 and exo-AAV8 or exo-AAV5 vectors expressing human coagulation factor IX (hF. IX) was evaluated. A significant enhancement of transduction efficiency was observed, and in hemophilia B mice treated with 4 x 10(10) vector genomes per kilogram of exo-AAV8 vectors, a staggering; 1 log increase in hF. IX transgene expression was observed, leading to superior correction of clotting time. Enhanced liver expression was also associated with an increase in the frequency of regulatory T cells in lymph nodes. The efficiency of exo- and standard AAV8 vectors in evading preexisting NAbs to the capsid was then evaluated in a passive immunization mouse model and in human sera. Exo-AAV8 gene delivery allowed for efficient transduction even in the presence of moderate NAb titers, thus potentially extending the proportion of subjects eligible for liver gene transfer. Exo-AAV vectors therefore represent a platform to improve the safety and efficacy of liver-directed gene transfer

Rescue of Pompe disease in mice by AAV-mediated liver delivery of secretable acid α-glucosidase

International audienceLiver delivery of engineered GAA transgenes to mice with Pompe disease rescued glycogen accumulation in multiple tissues