Extracellular HMGB1 regulates multi-walled carbon nanotube-induced inflammation in vivo

Abstract

Endotoxin is often used to activate NF-κB in vitro when assessing NLRP3 inflammasome activation by various exogenous particles including nanoparticles. However, the endogenous source of this signal 1 is unknown. High-mobility group box 1 (HMGB1) is known to play a critical role in acute lung injury, however the potential contribution of the alarmin HMGB1 to NLRP3 Inflammasome activation has not been determined in response to nanoparticles in vivo. In this study, the ability of multi-walled carbon nanotubes (MWCNT) to cause release of HMGB1 in vitro and in vivo, as well as the potential of HMGB1 to function as signal 1 in vitro and in vivo, was determined. HMGB1 activity in vivo was assessed by administration of HMGB1 neutralization antibodies following MWCNT exposure. Caspase-1−/− mice were utilized to elucidate the dependence of HMGB1 secretion on NLRP3 inflammasome activity. MWCNT exposure increased extracellular HMGB1 levels in primary alveolar macrophages from C57Bl/6 mice and C10 mouse epithelial cell culture supernatants, and in C57Bl/6 mouse lung lavage fluid. MWCNT-induced HMGB1 secretion was dependent upon caspase-1. HMGB1 increased MWCNT-induced IL-1β release from macrophages in vitro, and neutralization of extracellular HMGB1 reduced MWCNT-induced IL-1β secretion in vivo. HMGB1 neutralization was accompanied with overall decreased inflammation. In summary, this study suggests extracellular HMGB1 participates in NLRP3 inflammasome activity and regulates IL-1β associated sterile inflammation induced by MWCNT.

Phagolysosome acidification is required for silica and engineered nanoparticle-induced lysosome membrane permeabilization and resultant NLRP3 inflammasome activity

“…Cell supernatants and cell free lavage fluid were assessed for IL-1β and IL-18 by ELISA as previously described. HMGB1 was measured by ELISA using commercially available antibodies (R&D Systems; EMD Millipore, Billerica, MA, USA; Santa-Cruz Biotech, Dallas, TX, USA) as previously described (Jessop and Holian, 2015). Whole Lung lavage fluid was also assessed for LDH activity (Promega, Madison, WI, USA) and protein content using the BCA assay (Thermo Fisher Scientific, Waltham, MA, USA).…”

It takes two to tango: Understanding the interactions between engineered nanomaterials and the immune system

“…It should be noted that the in vitro assessment of inflammasome activation is usually performed using LPS-primed cells, implying that nanoparticles exposure alone might not be sufficient to induce inflammasome activation and that other concomitant signals would be required in a living organism. Interestingly, MWCNT exposure was recently shown to increase secretion of extracellular HMGB1 (an endogenous stress signal or DAMP) in alveolar macrophages, and neutralization of extracellular HMGB1 reduced MWCNT-induced IL-1b secretion in vivo [67]. This provides a basis for the sterile inflammation triggered by MWCNTs.…”

Environmental impact of multi-wall carbon nanotubes in a novel model of exposure: systemic distribution, macrophage accumulation, and amyloid deposition

“…CNTs have been previously associated with foreign body reactions, 21,23 including migration, activation of immune cells and induction of frustrated phagocytosis, 25 and activation of the NLRP3 inflammasome, 3,[27][28][29][30]41 leading to inflammation. 60 The nanometer scale and needle shape of CNTs recall that of crocidolite asbestos fibers, 54 and CNT administration has been associated with inflammation, fibrosis, and mesothelioma.…”

“…14,[20][21][22][23] The effects of pristine (nonfunctionalized) CNTs most commonly involve immune innate reactions, including enhancement of oxidative damage, 24 fibrosis, 13,22,23 collagen-rich granuloma formation, 23 and inflammation. [25][26][27][28][29][30] When entering biological fluids, CNTs are rapidly coated by proteins, forming a biological protein corona. 31,32 In particular, the hydrophobic interactions between CNTs and proteins could also play a role in inducing proteins to form a cross-sheet, a characteristic of amyloid.…”

“…36 In this context, data concerning the ability of CNTs to induce protein aggregation and amyloid fiber formation are controversial. [37][38][39][40] The NLRP3 inflammasome, associated with immune responses to CNTs, [27][28][29][30]41 activates release of IL-18, 42 a cytokine associated with amyloid plaque formation in Alzheimer's disease, [43][44][45][46] a neurodegenerative disorder characterized by amyloid accumulation. For these reasons, we investigated the ability of CNTs to induce amyloid production and deposition in vivo, an innate defense mechanism present in most eukaryotic phyla ranging from fungi and invertebrates [47][48][49] to humans.…”