Past project's Collaborator
Stéphanie LONGET (to March 2014)
In collaboration with Sylvia Miescher and Adrian Zuercher, CSL Behring-Bern
Immunotherapy with monoclonal and polyclonal immunoglobulin is successfully applied to improve many clinical conditions, including infection, autoimmune diseases or immunodeficiency. Most immunoglobulin products - recombinant or plasma-derived - are based on IgG antibodies, whereas to date the use of IgA for therapeutic application has remained anecdotal. In particular, purification or production of large quantities of secretory IgA (SIgA)4 for potential mucosal application has not been achieved. In this project, we find that polymeric IgA (pIgA) recovered from human plasma is able to associate with secretory component (SC) to generate SIgA-like molecules. The recombinant SC associates covalently in a 1:1 stoichiometry with pIgA and with similar efficacy as colostrum-derived SC. In comparison with pIgA, the association with SC delays degradation of SIgA by intestinal proteases. In vitro, plasma-derived IgA and SIgA neutralizes Shigella flexneri used as a model pathogen, resulting in a delay of bacteria-induced damage targeted to polarized Caco-2 cell monolayers. The data demonstrates that association of plasma-derived IgA or IgM with recombinant/colostrum-derived SC is feasible and yields SIgA-like molecules with similar biochemical and functional characteristics as mucosa-derived immunoglobulins.
Integrity of Caco-2 cell monolayers infected with Shigella flexneri alone or in combination with various IgA preparations.
A, laser scanning confocal microscopy (LSCM) 3D reconstructed images (snapshot) of Caco-2 cell monolayers exposed to 2 x 107S. flexneri M90T alone or in combination with human plasma-derived pIgA, SIgA or mIgA for 13 hours. Tight junctions stabilizing the monolayer are visualized with ZO-1 labeling (red). Caco-2 cells are visualized via nuclear staining with DAPI (blue) and bacteria constitutively expressing GFP stain green. Control monolayers are the non-infected Caco-2 cell monolayers (no bacteria). Scale bars: 50 µm.
B. For each condition, the sum of infected areas was determined from LSCM pictures of whole filters using ImageJ software.