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: Mikhail A Gavrilin, Srabani Mitra, Sudarshan Seshadri, Jyotsna Nateri, Freweine Berhe, Mark W Hall, Mark D Wewers
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 182 Issue 12 Pg. 7982-9 (Jun 15 2009) ISSN: 1550-6606 [Electronic] United States
• PMID: 19494323 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Cytoskeletal Proteins
• Interleukin-1beta
• MEFV protein, human
• Pyrin
• RNA, Small Interfering
• Macrophage Colony-Stimulating Factor
• Caspase 1

Topics

• Caspase 1 (metabolism)
• Cells, Cultured
• Cytoskeletal Proteins (genetics, immunology, metabolism)
• Francisella (immunology)
• Humans
• Interleukin-1beta (immunology, metabolism)
• Macrophage Colony-Stimulating Factor (pharmacology)
• Macrophages (drug effects, immunology, metabolism)
• Pyrin
• RNA, Small Interfering (genetics)