Abstract
With the rapid development of synthetic alternatives to mineral fibers, their possible effects on the environment and human health have become recognized as important issues worldwide. This study investigated effects of four fibrous materials, i.e. nanofibrillar/nanocrystalline celluloses (NCF and CNC), single-walled carbon nanotubes (CNTs), and crocidolite asbestos (ASB), on pulmonary inflammation and immune responses found in the lungs, as well as the effects on spleen and peripheral blood immune cell subsets. BALB/c mice were given NCF, CNC, CNT, and ASB on Day 1 by oropharyngeal aspiration. At 14 days post-exposure, the animals were evaluated. Total cell number, mononuclear phagocytes, polymorphonuclear leukocytes, lymphocytes, and LDH levels were significantly increased in ASB and CNT-exposed mice. Expression of cytokines and chemokines in bronchoalveolar lavage (BAL) was quite different in mice exposed to four particle types, as well as expression of antigen presentation-related surface proteins on BAL cells. The results revealed that pulmonary exposure to fibrous materials led to discrete local immune cell polarization patterns with a TH2-like response caused by ASB and TH1-like immune reaction to NCF, while CNT and CNC caused non-classical or non-uniform responses. These alterations in immune response following pulmonary exposure should be taken into account when testing the applicability of new nanosized materials with fibrous morphology.
Highlights
A variety of new synthetic organic and inorganic filamentous materials have been developed in recent years with the intention to replace some of the existing industrially used mineral fibers, including asbestos (ASB)
The increase was highest in ASBtreated mice, i.e. up to four-fold (Figure 3(A,B)). Both polymorphonuclear leukocytes (PMNs) and LMPHs were almost non-detectable in the BALF of control mice, whereas they were clearly present in all treated mice, especially in the ASB-exposed hosts (Figure 3(C,D))
The goal of the current study was to determine whether fibrillary nanocellulose, despite having the same chemical composition as the crystalline form, elicits different local and systemic subacute immune responses upon pulmonary exposure in a mouse model of bolus pharyngeal aspiration, and second, if the response would be closer to the one produced by micro-sized crocidolite fibers or carbon nanotubes (CNTs)
Summary
A variety of new synthetic organic and inorganic filamentous materials have been developed in recent years with the intention to replace some of the existing industrially used mineral fibers, including asbestos (ASB). A long and tragic history of sustained and sometimes uncontrolled exposure to ASB and other mineral fibers in occupational and natural settings has proved that fibrous airborne materials may cause pulmonary inflammation, fibrosis, and cancer, having a significant impact on both individuals and the whole communities. There are additional concerns regarding the potential toxicity based on the fiber origin, chemistry, structure, biopersistence, and other characteristics that render the particle hazardous. Fibrous nanocellulose has a great potential for applications in different fields due to its unique properties such as mechanical strength, plasticity, viscosity, and film-forming features. Three types of nanocellulose – cellulose nanocrystals (CNCs), cellulose nanofibrills (NCF), and bacterial nano-cellulose – are produced, with NCF considered to be more suitable for biomedicine application because of its low rigidity and amorphous cellulose structure
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