Multi-Walled Carbon Nanotube Instillation Impairs Pulmonary Function in C57BL/6 Mice

Abstract

BackgroundMulti-walled carbon nanotubes (MWCNTs) are widely used in many disciplines due to their unique physical and chemical properties. Therefore, some concerns about the possible human health and environmental impacts of manufactured MWCNTs are rising. We hypothesized that instillation of MWCNTs impairs pulmonary function in C57BL/6 mice due to development of lung inflammation and fibrosis.MethodsMWCNTs were administered to C57BL/6 mice by oropharyngeal aspiration (1, 2, and 4 mg/kg) and we assessed lung inflammation and fibrosis by inflammatory cell infiltration, collagen content, and histological assessment. Pulmonary function was assessed using a FlexiVent system and levels of Ccl3, Ccl11, Mmp13 and IL-33 were measured by RT-PCR and ELISA.ResultsMice administered MWCNTs exhibited increased inflammatory cell infiltration, collagen deposition and granuloma formation in lung tissue, which correlated with impaired pulmonary function as assessed by increased resistance, tissue damping, and decreased lung compliance. Pulmonary exposure to MWCNTs induced an inflammatory signature marked by cytokine (IL-33), chemokine (Ccl3 and Ccl11), and protease production (Mmp13) that promoted the inflammatory and fibrotic changes observed within the lung.ConclusionsThese results further highlight the potential adverse health effects that may occur following MWCNT exposure and therefore we suggest these materials may pose a significant risk leading to impaired lung function following environmental and occupational exposures.

Intravenously delivered graphene nanosheets and multiwalled carbon nanotubes induce site-specific Th2 inflammatory responses via the IL-33/ST2 axis

“…12,13 Furthermore, we have demonstrated that these MWCNT-induced Th2 immune responses are mediated by mast cell activation in the pulmonary system through the IL-33/ST2 axis. 13 In our current study, we compared the systemic immune responses that were initiated following iv delivery of GNS and MWCNT.…”

“…12,13 To investigate whether iv injection of CBN activates the IL-33/ST2 axis, we first examined protein levels of IL-33 and sST2 in BALF. At 1 day postinjection, C57BL/6 mice injected with 1 mg/kg of GNS (2) demonstrated a significant increase in both IL-33 and sST2 levels in BALF compared to vehicle-injected mice (Figure 2A Given that IL-33 induces the release of Th2 cytokines through the ST2 receptor in a variety of immune cells, we examined protein levels of IL-5, IL-13, and interferon (IFN)-γ in BALF of C57BL/6 and ST2 -/-mice 1 or 7 days following a single injection of CBN.…”

“…12 Briefly, BAL was performed on the right lung of each mouse four separate times each with an individual volume based on body weight (26.25 mL/kg of body weight) of Hanks balanced salt solution. The first aliquot of BAL fluid (BALF) was collected separately for cytokine analysis, while aliquots 2-4 were pooled.…”

“…12,13 IL-33 is a novel member of the IL-1 family of cytokines that includes IL-1α/β, IL-1Ra, and IL-18.…”

Occupational Nanosafety Considerations for Carbon Nanotubes and Carbon Nanofibers

“…These inflammatory and fibrotic pulmonary responses to CNTs have also been associated with measurable alterations of pulmonary function, that is, an increase in expiratory time with SWCNTs and decreased compliance with increased resistance with aspiration of MWCNTs. 13,20 Evidence also indicates that SWCNT exposure also decreases the ability of the lung to resist infection. 21 Recent studies indicate that functionalization of MWCNTs with −COOH groups significantly decreases the inflammatory and fibrotic response after aspiration in a mouse model.…”