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

Abstract

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]-1β to mature IL-1β). 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-1β release induced by metal ions are oxidative stress-dependent; and 2. IL-1β release induced by metal ions is NF-κB signaling pathway-dependent. Lipopolysaccharide (LPS)-primed murine bone marrow-derived macrophages (BMDM) were exposed to Co2+ (6–48 ppm), Cr3+ (100–500 ppm), or Ni2+ (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-κB inhibitor (JSH-23). Culture supernatants were analyzed for caspase-1 by western blotting and/or IL-1β release by ELISA. Immunoblotting revealed the presence of caspase-1 (p20 subunit) in supernatants of BMDM incubated with Cr3+, but not with Ni2+ or Co2+. When L-AA (2 mM) was present with Cr3+, the caspase-1 p20 subunit was undetectable and IL-1β release decreased down to the level of the negative control, thereby demonstrating that caspase-1 activation and IL-1β release induced by Cr3+ was oxidative stress-dependent. ELISA demonstrated that Cr3+ induced the highest release of IL-1β, while Co2+ had no or limited effects. In the presence of Ni2+, the addition of L-AA (2 mM) also decreased IL-1β release, below the level of the negative control, suggesting that IL-1β release induced by Ni2+ was also oxidative stress-dependent. Finally, when present during both priming with LPS and activation with Cr3+, JSH-23 blocked IL-1β release, demonstrating NF-κB involvement. Overall, this study showed that while both Cr3+ and Ni2+ may be inducing inflammasome activation, Cr3+ is likely a more potent activator, acting through oxidative stress and the NF-κB signaling pathway.

Comparison of Inflammatory Effects in THP-1 Monocytes and Macrophages after Exposure to Metal Ions

“…In contrast, chromium ions did not cause a significant decrease in cell activity. Investigations by Ferko et al [22] and Kwon et al [16] further support the assumption of cobalt and nickel ions having a stronger impact on monocytes and macrophages in the applied concentrations. Cell death studies by Huk et al [23] proved that chromium ion toxicity needed much higher concentrations than in cobalt stimulation to manifest.…”

“…In solution, they form aggregates in the cell culture medium. However, very high concentrations of chromium ions that exceed the investigated range may be able to induce hypoxia in the cell and cause a decrease in viability [22,25]. However, since chromium (VI) ions exhibit up to 1000-fold higher toxicity than chromium(III) ions, our results may not adequately reflect the in vivo effects of chromium [26].…”

Tumor necrosis factor primes and metal particles activate the NLRP3 inflammasome in human primary macrophages

“…While both Cr and Mo particles activated the NLRP3 inflammasome, no direct conclusions can be made for the inflammasome activating potential of CrMo alloy particles. The proposed stimulatory effects of Co 2+ and other metal ions, as well as cobalt based implant debris also remain speculative [51,52].…”

Update of the risk assessment of nickel in food and drinking water

“…This implies that such genes may also be involved in the effects of oral exposure of sensitive individuals. Studies with macrophages performed by Ferko and Catelas (2018) have shown that nickel ions can activate the NLRP3 inflammasome, via oxidative stress and NF-jB signalling. This is in line with studies by Li et al (2013) and Li and Zhong (2014), indicating that nickel (II) activates the NLRP3-ASC-caspase-1 immune signalling pathway in antigen-presenting cells, leading to release of the pro-inflammatory cytokine IL-1b.…”

“…This implies that such genes may also be involved in the effects of oral exposure of sensitive individuals. Studies with macrophages performed by Ferko and Catelas (2018) have shown that nickel ions can activate the NLRP3 inflammasome, via oxidative stress and NF‐κB signalling. This is in line with studies by Li et al.…”