title: Pyrin critical to macrophage IL-1beta response to Francisella challenge.
abstract: Relative to monocytes, human macrophages are deficient in their ability to process and release IL-1beta. In an effort to explain this difference, we used a model of IL-1beta processing and release that is dependent upon bacterial escape into the cytosol. Fresh human blood monocytes were compared with monocyte-derived macrophages (MDM) for their IL-1beta release in response to challenge with Francisella novicida. Although both cell types produced similar levels of IL-1beta mRNA and intracellular pro-IL-1beta, only monocytes readily released processed mature IL-1beta. Baseline mRNA expression profiling of candidate genes revealed a remarkable deficiency in the pyrin gene, MEFV, expression in MDM compared with monocytes. Immunoblots confirmed a corresponding deficit in MDM pyrin protein. To determine whether pyrin levels were responsible for the monocyte/MDM difference in mature IL-1beta release, pyrin expression was knocked down by nucleofecting small interfering RNA against pyrin into monocytes or stably transducing small interfering RNA against pyrin into the monocyte cell line, THP-1. Pyrin knockdown was associated with a significant drop in IL-1beta release in both cell types. Importantly, M-CSF treatment of MDM restored pyrin levels and IL-1beta release. Similarly, the stable expression of pyrin in PMA-stimulated THP-1-derived macrophages induces caspase-1 activation, associated with increased IL-1beta release after infection with F. novicida. In summary, intracellular pyrin levels positively regulate MDM IL-1beta responsiveness to Francisella challenge.
authors.affiliation: Division of Pulmonary Allergy Critical Care and Sleep Medicine, Davis Heart and Lung Research Institute, Ohio State University, Columbus, OH 43210, USA. gavrilin.1@osu.edu
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Gavrilin
authors.forename: Srabani
authors.initials: S
authors.lastname: Mitra
authors.forename: Sudarshan
authors.initials: S
authors.lastname: Seshadri
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Nateri
authors.forename: Freweine
authors.initials: F
authors.lastname: Berhe
authors.forename: Mark W
authors.initials: MW
authors.lastname: Hall
authors.forename: Mark D
authors.initials: MD
authors.lastname: Wewers
mesh_terms: D020170:Caspase 1 / Q000378:metabolism; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005603:Francisella / Q000276:immunology*; D006801:Humans; D053583:Interleukin-1beta / Q000276:immunology* / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D000071198:Pyrin; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D003598:Cytoskeletal Proteins; D053583:Interleukin-1beta; C000604192:MEFV protein, human; D000071198:Pyrin; D034741:RNA, Small Interfering; D016173:Macrophage Colony-Stimulating Factor; D020170:Caspase 1