Toxins 2013, 5(6), 1105-1118; doi:10.3390/toxins5061105

Reduction of Streptolysin O (SLO) Pore-Forming Activity Enhances Inflammasome Activation

1email, 2email, 3email, 2email and 1,* email
Received: 1 March 2013; in revised form: 29 May 2013 / Accepted: 3 June 2013 / Published: 6 June 2013
(This article belongs to the Special Issue Pore-Forming Toxins)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Pore-forming toxins are utilized by bacterial and mammalian cells to exert pathogenic effects and induce cell lysis. In addition to rapid plasma membrane repair, macrophages respond to pore-forming toxins through activation of the NLRP3 inflammasome, leading to IL-1β secretion and pyroptosis. The structural determinants of pore-forming toxins required for NLRP3 activation remain unknown. Here, we demonstrate using streptolysin O (SLO) that pore-formation controls IL-1β secretion and direct toxicity. An SLO mutant incapable of pore-formation did not promote direct killing, pyroptosis or IL-1β production. This indicated that pore formation is necessary for inflammasome activation. However, a partially active mutant (SLO N402C) that was less toxic to macrophages than wild-type SLO, even at concentrations that directly lysed an equivalent number of red blood cells, enhanced IL-1β production but did not alter pyroptosis. This suggests that direct lysis may attenuate immune responses by preventing macrophages from successfully repairing their plasma membrane and elaborating more robust cytokine production. We suggest that mutagenesis of pore-forming toxins represents a strategy to enhance adjuvant activity.
Keywords: NLRP3; inflammasome; Caspase-1; plasma membrane repair; streptolysin O
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MDPI and ACS Style

Keyel, P.A.; Roth, R.; Yokoyama, W.M.; Heuser, J.E.; Salter, R.D. Reduction of Streptolysin O (SLO) Pore-Forming Activity Enhances Inflammasome Activation. Toxins 2013, 5, 1105-1118.

AMA Style

Keyel PA, Roth R, Yokoyama WM, Heuser JE, Salter RD. Reduction of Streptolysin O (SLO) Pore-Forming Activity Enhances Inflammasome Activation. Toxins. 2013; 5(6):1105-1118.

Chicago/Turabian Style

Keyel, Peter A.; Roth, Robyn; Yokoyama, Wayne M.; Heuser, John E.; Salter, Russell D. 2013. "Reduction of Streptolysin O (SLO) Pore-Forming Activity Enhances Inflammasome Activation." Toxins 5, no. 6: 1105-1118.

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