title: Discovering Molecules That Regulate Efferocytosis Using Primary Human Macrophages and High Content Imaging.
abstract: Defective clearance of apoptotic cells can result in sustained inflammation and subsequent autoimmunity. Macrophages, the "professional phagocyte" of the body, are responsible for efficient, non-phlogistic, apoptotic cell clearance. Controlling phagocytosis of apoptotic cells by macrophages is an attractive therapeutic opportunity to ameliorate inflammation. Using high content imaging, we have developed a system for evaluating the effects of antibody treatment on apoptotic cell uptake in primary human macrophages by comparing the Phagocytic Index (PI) for each antibody. Herein we demonstrate the feasibility of evaluating a panel of antibodies of unknown specificities obtained by immunization of mice with primary human macrophages and show that they can be distinguished based on individual PI measurements. In this study ~50% of antibodies obtained enhance phagocytosis of apoptotic cells while approximately 5% of the antibodies in the panel exhibit some inhibition. Though the specificities of the majority of antibodies are unknown, two of the antibodies that improved apoptotic cell uptake recognize recombinant MerTK; a receptor known to function in this capacity in vivo. The agonistic impact of these antibodies on efferocytosis could be demonstrated without addition of either of the MerTK ligands, Gas6 or ProS. These results validate applying the mechanism of this fundamental biological process as a means for identification of modulators that could potentially serve as therapeutics. This strategy for interrogating macrophages to discover molecules regulating apoptotic cell uptake is not limited by access to purified protein thereby increasing the possibility of finding novel apoptotic cell uptake pathways.
authors.affiliation: Janssen Research & Development, LLC, 1400 Welsh & McKean Rds., Spring House, PA, 19477, United States of America.
authors.forename: Sandra
authors.initials: S
authors.lastname: Santulli-Marotto
authors.affiliation: Janssen Research & Development, LLC, 1400 Welsh & McKean Rds., Spring House, PA, 19477, United States of America.
authors.forename: Alexis
authors.initials: A
authors.lastname: Gervais
authors.affiliation: Janssen Research & Development, LLC, 1400 Welsh & McKean Rds., Spring House, PA, 19477, United States of America.
authors.forename: Jamie
authors.initials: J
authors.lastname: Fisher
authors.affiliation: Janssen Research & Development, LLC, 1400 Welsh & McKean Rds., Spring House, PA, 19477, United States of America.
authors.forename: Brandy
authors.initials: B
authors.lastname: Strake
authors.affiliation: Janssen Research & Development, LLC, 1400 Welsh & McKean Rds., Spring House, PA, 19477, United States of America.
authors.forename: Carol Anne
authors.initials: CA
authors.lastname: Ogden
authors.affiliation: FlowMetric, Inc., 3805 Old Easton Road, Doylestown, PA, 18902, United States of America.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Riveley
authors.affiliation: Janssen Research & Development, LLC, 1400 Welsh & McKean Rds., Spring House, PA, 19477, United States of America.
authors.forename: Jill
authors.initials: J
authors.lastname: Giles-Komar
mesh_terms: D000818:Animals; D000906:Antibodies / Q000145:classification / Q000276:immunology*; D017209:Apoptosis; D002478:Cells, Cultured; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000276:immunology; D000076202:c-Mer Tyrosine Kinase
chemical_list: D000906:Antibodies; D011518:Proto-Oncogene Proteins; C097072:MERTK protein, human; D020794:Receptor Protein-Tyrosine Kinases; D000076202:c-Mer Tyrosine Kinase