Pre-existing immunity to adeno-associated virus (AAV) is highly prevalent in humans and can profoundly impact transduction efficiency. Despite the relevance to AAV-mediated gene transfer, relatively little is known about the fate of AAV vectors in the presence of neutralizing antibodies (NAbs). Similarly, the effect of binding antibodies (BAbs), with no detectable neutralizing activity, on AAV transduction is ill defined. Here, we delivered AAV8 vectors to mice carrying NAbs and demonstrated that AAV particles are taken up by both liver parenchymal and non-parenchymal cells; viral particles are then rapidly cleared, without resulting in transgene expression. In vitro, imaging of hepatocytes exposed to AAV vectors pre-incubated with either NAbs or BAbs revealed that virus is taken up by cells in both cases. Whereas no successful transduction was observed when AAV was pre-incubated with NAbs, an increased capsid internalization and transgene expression was observed in the presence of BAbs. Accordingly, AAV8 vectors administered to mice passively immunized with anti-AAV8 BAbs showed a more efficient liver transduction and a unique vector biodistribution profile compared to mice immunized with NAbs. These results highlight a virtually opposite effect of neutralizing and binding antibodies on AAV vectors transduction.

Fabry disease is an X-linked lysosomal storage disease in which mutations of the gene (GLA) cause a deficiency of the lysosomal hydrolase α-galactosidase A (α-Gal). This defect results in an accumulation of glycosphingolipids, primarily globotriaosylceramide (Gb3) which causes a multisystemic vasculopathy. Available since 2001 in Europe, enzyme replacement therapy consists in the administration of agalsidase, a recombinant form of α-galactosidase A. Enzyme replacement therapy was shown to improve the global prognosis but allowed partial success in preventing critical events such as strokes and cardiac arrests. As in most lysosomal storage diseases, frequent immune reactions have been described in naive Fabry disease patients. Humoral immune responses following enzyme replacement therapy have also been described, with unclear consequences on the progression of the disease. While cost-effectiveness of enzyme replacement therapy in Fabry disease begins to be questioned and new therapeutic strategies arise such as chaperone or gene therapy, it appears necessary to better understand the immune responses observed in the treatment of naive patients and during enzyme replacement therapy with agalsidase. We propose a comprehensive review of the available literature concerning both innate and adaptive responses observed in Fabry disease. We particularly highlight the probable role of the toll-like receptor 4 (TLR4) and CD1d pathways triggered by Gb3 accumulation in the development of local and systemic inflammation that could lead to irreversible organ damages. We propose an immunological point of view of Fabry disease pathogenesis involving immune cells notably the invariant natural killer T cells. We finally review anti-agalsidase antibodies, their development and impact on outcomes.

Three Nod-like receptors (NLR family, pyrin domain containing 1/NLRP1, NLR family, pyrin domain containing 3/NLRP3, NLR family, CARD domain containing 4/NLRC4) and the adaptor molecule PYD and CARD domain containing protein/PYCARD are involved in the assembling of multiprotein complexes known as inflammasomes, leading to caspase 1 activation and consequent interleukin (IL)-1β secretion. Considering that inflammasomes are involved in sensing pathogens and in triggering inflammatory and immune response, we hypothesized that they could also act in the placenta as an efficient innate mechanism during pregnancy infections. For this reason the activation of inflammasome was tested in 3 human placental cell populations in the presence of a common gram-negative compound (lipopolysaccharide [LPS]). The transcription of NLRP1, NLRP3, NLRC4, PYCARD, CASP1, and IL1B genes and the secretion of IL-1β were evaluated in human first trimester cytotrophoblasts (CTBs), decidual stromal cells (DSCs), and endothelial cells (DECs) stimulated with LPS. In CTBs and DSCs, LPS induced an augmented expression of CASP1 and IL1B and the specific upregulation of NLRP3 within the 3 NLRs tested. Moreover, LPS induced secretion of IL-1β from CTBs and DSCs. These results suggest the involvement of NLRP3 inflammasome in the placental innate response. The LPS did not affect inflammasome gene transcription and IL-1β production in DECs. Bacterial LPS enhances NLRP3 inflammasome components in trophoblast and DSCs, suggesting that this innate immune complex could play a key role in placental immune defense.