Effects of metal ions on caspase-1 activation and interleukin-1[beta] release in murine bone marrow-derived macrophages

• Published in: PloS one Vol. 13; no. 8; p. e0199936
• Main Authors: Ferko, Maxime-Alexandre, Catelas, Isabelle
• Format: Journal Article
• Language: English
• Published: Public Library of Science 23-08-2018
• Subjects: Bone marrow; Caspases; Health aspects; Interleukin-1; Macrophages; Metal ions; Rats
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0199936

Ions released from metal implants have been associated with adverse tissue reactions and are therefore a major concern. Studies with macrophages have shown that cobalt, chromium, and nickel ions can activate the NLRP3 inflammasome, a multiprotein complex responsible for the activation of caspase-1 (a proteolytic enzyme converting pro-interleukin [IL]-1[beta] to mature IL-1[beta]). However, the mechanism(s) of inflammasome activation by metal ions remain largely unknown. The objectives of the present study were to determine if, in macrophages: 1. caspase-1 activation and IL-1[beta] release induced by metal ions are oxidative stress-dependent; and 2. IL-1[beta] release induced by metal ions is NF-[kappa]B signaling pathway-dependent. Lipopolysaccharide (LPS)-primed murine bone marrow-derived macrophages (BMDM) were exposed to Co.sup.2+ (6-48 ppm), Cr.sup.3+ (100-500 ppm), or Ni.sup.2+ (12-96 ppm), in the presence or absence of a caspase-1 inhibitor (Z-WEHD-FMK), an antioxidant (L-ascorbic acid [L-AA]), or an NF-[kappa]B inhibitor (JSH-23). Culture supernatants were analyzed for caspase-1 by western blotting and/or IL-1[beta] release by ELISA. Immunoblotting revealed the presence of caspase-1 (p20 subunit) in supernatants of BMDM incubated with Cr.sup.3+, but not with Ni.sup.2+ or Co.sup.2+ . When L-AA (2 mM) was present with Cr.sup.3+, the caspase-1 p20 subunit was undetectable and IL-1[beta] release decreased down to the level of the negative control, thereby demonstrating that caspase-1 activation and IL-1[beta] release induced by Cr.sup.3+ was oxidative stress-dependent. ELISA demonstrated that Cr.sup.3+ induced the highest release of IL-1[beta], while Co.sup.2+ had no or limited effects. In the presence of Ni.sup.2+, the addition of L-AA (2 mM) also decreased IL-1[beta] release, below the level of the negative control, suggesting that IL-1[beta] release induced by Ni.sup.2+ was also oxidative stress-dependent. Finally, when present during both priming with LPS and activation with Cr.sup.3+, JSH-23 blocked IL-1[beta] release, demonstrating NF-[kappa]B involvement. Overall, this study showed that while both Cr.sup.3+ and Ni.sup.2+ may be inducing inflammasome activation, Cr.sup.3+ is likely a more potent activator, acting through oxidative stress and the NF-[kappa]B signaling pathway.