Evaluation of the NLRP3 Inflammasome Activating Effects of a Large Panel of TiO2 Nanomaterials in Macrophages

Abstract

TiO2 nanomaterials are among the most commonly produced and used engineered nanomaterials (NMs) in the world. There is controversy regarding their ability to induce inflammation-mediated lung injuries following inhalation exposure. Activation of the NACHT, LRR and PYD domains-containing protein 3 (NALP3) inflammasome and subsequent release of the cytokine interleukin (IL)-1β in pulmonary macrophages has been postulated as an essential pathway for the inflammatory and associated tissue-remodeling effects of toxic particles. Our study aim was to determine and rank the IL-1β activating properties of TiO2 NMs by comparing a large panel of different samples against each other as well as against fine TiO2, synthetic amorphous silica and crystalline silica (DQ12 quartz). Effects were evaluated in primary bone marrow derived macrophages (BMDMs) from NALP3-deficient and proficient mice as well as in the rat alveolar macrophage cell line NR8383. Our results show that specific TiO2 NMs can activate the inflammasome in macrophages albeit with a markedly lower potency than amorphous SiO2 and quartz. The heterogeneity in IL-1β release observed in our study among 19 different TiO2 NMs underscores the relevance of case-by-case evaluation of nanomaterials of similar chemical composition. Our findings also further promote the NR8383 cell line as a promising in vitro tool for the assessment of the inflammatory and inflammasome activating properties of NMs.

Assessing the NLRP3 Inflammasome Activating Potential of a Large Panel of Micro- and Nanoplastics in THP-1 Cells

“…To compare the reaction of THP-1 cells with the reaction of BMDMs reported by Kolling et al [ 29 ], WT and NLRP3 −/− cells were treated with four different samples of TiO 2 nanoparticles ( Figure 4 ).…”

“…The release of IL-1β after particle treatment of bone marrow-derived macrophages (BMDMs) isolated from wildtype (WT) or Nlrp3 knockout mice, has previously been assessed in our laboratory as an ex vivo approach to investigate the ability of a large panel of different titanium dioxide (TiO 2 ) nanomaterials to activate the NLRP3 inflammasome [ 29 ]. In light of the 3Rs, especially to replace the use of animals with alternative in vitro methods [ 30 ], we used CRISPR/Cas technology in our present study to generate THP-1 NLRP3 −/− cells and utilized the THP-1 cell line as a suitable alternative to BMDMs isolated from mice.…”

Ingested Engineered Nanomaterials Affect the Expression of Mucin Genes—An In Vitro-In Vivo Comparison

“…In E12 cell monocultures, the cell viability was assessed via WST-1 assay after 24 h exposure to 0, 10, 20, 40, and 80 µg ENM/cm 2 . The assay was performed as described by Kolling et al [53] and based on the nanOxiMet project's SOP "Cellular viability-WST-1 assay" (https://nanopartikel.info/data/projekte/nanOxiMet/SOP/nanOxiMet_SOP_ WST-1-assay_V2.pdf, accessed on 23 August 2021). WST-1 reagent was added to the cells at a dilution of 1:5 in exposure medium and the absorbance at 450 nm and 630 nm was measured after incubation for 1 h.…”

Curcuma phaeocaulis Inhibits NLRP3 Inflammasome in Macrophages and Ameliorates Nanoparticle-Induced Airway Inflammation in Mice

“…Some dangerous signals have been reported to activate NLRP3 inflammasome in various tissues and organs. For instance, in the respiratory tract tissue, SiO 2 and TiO 2 nanoparticles have been reported to trigger inflammatory responses involving IL-1β secretion in an NLRP3 inflammasome-dependent manner [ 6 , 7 , 8 , 9 , 10 ]. Of particular interest is the observation that both nanoparticles were able to synergistically induce the activation of macrophages at concentrations which neither of the nanoparticles alone was capable of activating inflammasome in animals [ 7 ].…”