Engineering highly multivalent sperm-binding IgG antibodies for potent non-hormonal female contraception

Many women risk unintended pregnancy due to dissatisfaction with available hormonal contraceptive methods. This led us to pursue topical sperm-binding monoclonal antibodies as a strategy for safe, non-hormonal contraception. Motivated by the greater agglutination potencies of polymeric immunoglobulins such as IgM and the exceptional bioprocessing ease in manufacturing IgG, we engineered IgGs possessing 6-10 Fabs against a unique surface antigen universally present on human sperm. These highly multivalent IgGs (HM-IgGs) are at least 10- to 16-fold more potent and faster than the parent IgG at agglutinating sperm, while preserving Fc-mediated trapping of individual spermatozoa in mucus. The increased potencies translate to effective (>99.9%) reduction of progressively motile sperm in the sheep vagina using 33 micrograms of the 10 Fab HM-IgG. HM-IgGs produce at comparable yields and possess identical thermal stability to the parent IgG, with greater homogeneity. HM-IgGs represent not only promising biologics for non-hormonal contraception but also a promising platform for generating potent agglutinating mAb for diverse medical applications.

TNF-α Mediated Secretory Component is Positively Regulated by PI3K/AKT/MTOR in CACO-2 Cells

Summary Background: Secretory component (SC) is the extracellular component of the polymeric immunoglobulin receptor (pIgR) that functions as a receptor for externally secreted polymeric immunoglobulins such as secretory IgA. SC expression is regulated by a signaling pathway involving TNF-a. Methods: Caco-2 cells were cotreated with TNF-a plus either Wortmannin, which inhibits PI3K, or Rapamycin, which inhibits mTOR. The expression of SC and pIgR mRNA were assessed by immunocytochemistry, Western blotting, and Quantitative real-time PCR. Results: Wortmannin and Rapamycin decreased the fraction of cells expressing SC, as well as the total expression of SC protein and pIgR mRNA. Conclusions: TNF-a regulation of SC expression is mediated through a PI3K/AKT/mTOR signaling pathway in Caco-2 cells.

In Polarized MDCK Cells Basolateral Vesicles Arise from Clathrin-γ-adaptin–coated Domains on Endosomal Tubules

Human transferrin receptors (TR) and receptors for polymeric immunoglobulins (pIgR) expressed in polarized MDCK cells maintain steady-state, asymmetric distributions on the separate basolateral and apical surfaces even though they are trafficking continuously into and across these cells. The intracellular mechanisms required to maintain these asymmetric distributions have not been located. Here we show that TR and pIgR internalize from both surfaces to a common interconnected endosome compartment that includes tubules with buds coated with clathrin lattices. These buds generate vesicles that carry TR to the basolateral border. The lattices contain γ-adaptin and are dispersed by treatment with brefeldin A (BFA). Since BFA treatment abrogates the vectorial trafficking of TR in polarized MDCK cells, we propose that the clathrin-coated domains of the endosome tubules contain the polarized sorting mechanism responsible for their preferential basolateral distribution.