Ohtsuka S, Ishii Y, Matsuyama M, Ano S, Morishima Y, Yanagawa T, Warabi E, Hizawa N. SQSTM1/p62/A170 regulates the severity of Legionella pneumophila pneumonia by modulating inflammasome activity.
Eur J Immunol 2014;
44:1084-92. [PMID:
24374573 DOI:
10.1002/eji.201344091]
[Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 12/07/2013] [Accepted: 12/20/2013] [Indexed: 01/19/2023]
Abstract
Sequestosome1/A170/p62 (SQSTM1) is a scaffold multifunctional protein involved in several cellular events, such as signal transduction, cell survival, cell death, and inflammation. SQSTM1 expression by macrophages is induced in response to environmental stresses; however, its role in macrophage-mediated host responses to environmental stimuli, such as infectious pathogens, remains unclear. In this study, we investigated the role of SQSTM1 in host responses to Legionella pneumophila, an intra-cellular pathogen that infects macrophages, in both an SQSTM1-deficient (SQSTM1(-/-) ) mouse model and macrophages from these mice. Compared with wild-type (WT) macrophages, the production and secretion of the proinflammatory cytokine IL-1β was significantly enhanced in SQSTM1(-/-) macrophages after infection with L. pneumophila. Inflammasome activity, indicated by the level of IL-18 and caspase-1 activity, was also elevated in SQSTM1(-/-) macrophages after infection with L. pneumophila. SQSTM1 may interact with nucleotide-binding oligomerization domain-like receptor family, caspase recruitment domain-containing 4 and nucleotide-binding oligomerization domain like receptor family, pyrin domain containing 3 proteins to inhibit their self-dimerization. Acute pulmonary inflammation induced by L. pneumophila and silica was enhanced in SQSTM1(-/-) mice with an increase in IL-1β levels in the bronchoalveolar lavage fluids. These findings suggest that SQSTM1 is a negative regulator of acute pulmonary inflammation, possibly by regulating inflammasome activity and subsequent proinflammatory cytokine production.
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