Nickel nanoparticles cause exaggerated lung and airway remodeling in mice lacking the T-box transcription factor, TBX21 (T-bet).
BACKGROUND
Nickel nanoparticles (NiNPs) are increasingly used in a variety of industrial applications, including the manufacturing of multi-walled carbon nanotubes (MWCNTs). While occupational nickel exposure is a known cause of pulmonary alveolitis, fibrosis, and cancer, the health risks of NiNPs are not well understood, especially in susceptible individuals such as asthmatics. The T-box transcription factor Tbx21 (T-bet) maintains Th1 cell development and loss of T-bet is associated with a shift towards Th2 type allergic airway inflammation that characterizes asthma. The purpose of this study was to determine the role of T-bet in susceptibility to lung remodeling by NiNPs or MWCNTs.


METHODS
Wild-type (WT) and T-bet-/- mice were exposed to NiNPs or MWCNTs (4 mg/kg) by oropharyngeal aspiration (OPA). Necropsy was performed at 1 and 21 days. Bronchoalveolar lavage fluid (BALF) was collected for differential counting of inflammatory cells and for measurement of cytokines by ELISA. The left lung was collected for histopathology. The right lung was analyzed for cytokine or mucin (MUC5AC and MUC5B) mRNAs.


RESULTS
Morphometry of alcian-blue/periodic acid Schiff (AB/PAS)-stained lung tissue showed that NiNPs significantly increased mucous cell metaplasia in T-bet-/- mice at 21 days (p < 0.001) compared to WT mice, and increased MUC5AC and MUC5B mRNAs (p < 0.05). MWCNTs also increased mucous cell metaplasia in T-bet-/- mice, but to a lesser extent than NiNPs. Chronic alveolitis was also increased by NiNPs, but not MWCNTs, in T-bet-/- mice compared to WT mice at 21 days (P < 0.001). NiNPs also increased IL-13 and eosinophils (p < 0.001) in BALF from T-bet-/- mice after 1 day. Interestingly, the chemokine CCL2 in the BALF of T-bet-/- mice was increased at 1 and 21 days (p < 0.001 and p < 0.05, respectively) by NiNPs, and to a lesser extent by MWCNTs at 1 day. Treatment of T-bet-/- mice with a monoclonal anti-CCL2 antibody enhanced NiNP-induced mucous cell metaplasia and MUC5AC mRNA levels (p < 0.05), yet marginally reduced NiNP-induced alveolitis.


CONCLUSIONS
These findings identify T-bet as a potentially important susceptibility factor for NiNP exposure and to a lesser extent for MWCNT exposure, and suggests that individuals with asthma are at greater risk.
Ellen E
EE
Glista-Baker
Alexia J
AJ
Taylor
Brian C
BC
Sayers
Elizabeth A
EA
Thompson
Environmental & Molecular Toxicology Program, Department of Biological Sciences, North Carolina State University, Campus Box 7633, Raleigh, North Carolina 27695, USA. james_bonner@ncsu.edu.
James C
JC
Bonner
D056151:Airway Remodeling / Q000187:drug effects*; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D018932:Chemokine CCL2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D003094:Collagen / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005355:Fibrosis / Q000473:pathology; D008168:Lung / Q000473:pathology*; D008171:Lung Diseases / Q000139:chemically induced* / Q000473:pathology*; D008297:Male; D053768:Metal Nanoparticles / Q000633:toxicity*; D008679:Metaplasia / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055271:Mucin 5AC / Q000235:genetics; D055257:Mucin-5B / Q000235:genetics; D009532:Nickel / Q000633:toxicity*; D011657:Pulmonary Eosinophilia / Q000473:pathology; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000473:pathology; D060888:Real-Time Polymerase Chain Reaction; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000502:physiology*; D000098815:T-bet Transcription Factor
D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D018932:Chemokine CCL2; C524679:Muc5ac protein, mouse; C524579:Muc5b protein, mouse; D055271:Mucin 5AC; D055257:Mucin-5B; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor; D009532:Nickel; D003094:Collagen