Effects of antimicrobial chemical exposures on influenza vaccination and antiviral immunity

Introduction

Healthcare workers concurrently may be at a higher risk of developing respiratory infections and allergic disease, such as asthma, than the general public. Increased incidence of allergic diseases is thought to be caused, in part, due to occupational exposure to chemicals that induce or augment Th2 immune responses. However, whether exposure to these chemical antimicrobials can influence immune responses to respiratory pathogens is unknown. Here, we use a BALB/c murine model to test if the Th2-promoting antimicrobial chemical triclosan influences immune responses to influenza A virus. Mice were dermally exposed to 2% triclosan for 7 days prior to infection with a sub-lethal dose of mouse adapted PR8 A(H1N1) virus (50 pfu); triclosan exposure continued until 10 days post infection (dpi). Infected mice exposed to triclosan did not show an increase in morbidity or mortality, and viral titers were unchanged. Assessment of T cell responses at 10 dpi showed a decrease in the number of total and activated (CD44^hi) CD4+ and CD8+ T cells at the site of infection (BAL and lung) in triclosan exposed mice compared to controls. Influenza-specific CD4+ and CD8+ T cells were assessed using MHCI and MHCII tetramers, with reduced populations, although not reaching statistical significance at these sites following triclosan exposure. Reductions in the Th1 transcription factor T-bet were seen in both activated and tetramer+ CD4+ and CD8+ T cells in the lungs of triclosan exposed infected mice, indicating reduced Th1 polarization and providing a potential mechanism for numerical reduction in T cells. Overall, these results indicate that the immune environment induced by triclosan exposure has the potential to influence the developing immune response to a respiratory viral infection and may have implications for healthcare workers who may be at an increased risk for developing infectious diseases.

Data Collection Methods

1. Animal Exposures
   • Female BALB/c mice (7-8 weeks at start of study)
   • Triclosan (2%) or acetone on dorsal surface of ear for 17 days
   • Intranasal infection with mouse-adapted A(H1N1) influenza A/Puerto Rico/8/34 (PR8)
   • Daily body weights recorded
2. Tissue Collection
   • Lung was frozen in liquid nitrogen or homogenized in RPMI
   • Bronchial alveolar lavage fluid
   • Lung associated lymph node collected into RPMI, then mechanically disrupted between the frosted ends of two microscope slides and filtered through a 70 μm pore filter to obtain a single cell suspension
   • Spleen collected into RPMI, then mechanically disrupted between the frosted ends of two microscope slides and filtered through a 70 μm pore filter to obtain a single cell suspension
3. Viral Detection in Lungs
   • Viral Plaque Assay (VPA) using Madin-Darby Canine Kidney (MDCK) cells
   • Tissue culture infective dose 50 % (TCID50) combined with hemagglutination (HA) assay
4. Cytokine production
   • Real-time PCR (Applied Biosystems 7500 RT-PCR System).  Genes investigated include Ifng, Tbet, Il4, Cxcr3, Foxp3, Lag3, Gata3, Tnf, Ifnar1, and Tslp
   • Luminex 200 system was used for to evaluate Th1/Th2/Th9/Th17/Th22/Treg Cytokine 17-Plex Mouse ProcartaPlex™ Panel.

5. Immune Cell Subsets
   • Flow cytometry using BD LSRII Flow Cytometer and data was analyzed using FlowJo software.

Publications Based on Dataset

Shane H, Othumpangat S, Marshall NB, Blachere F, Lukomska E, Dzubak L, Baur R, Noti J, Anderson S [2020]. Topical exposure to triclosan inhibits Th1 immune responses and reduces T cells responding to influenza infection in mice. PLoS ONE 15(12)(e0244436).

Acknowledgements

This project was supported by the National Institute for Occupational Safety and Health (NIOSH). When a publication makes use of this dataset, acknowledgement of the dataset should be attributed to NIOSH Health Effects Laboratory Division.

We would also like to recognize the work of Hillary L. Shane, Sreekumar Othumpangat, Nikki B. Marshall, Francoise Blachere, Ewa Lukomska, Lisa M. Weatherly, Rachel Baur, John D. Noti, and Stacey E. Anderson.

Contact

NIOSH/Health Effects Laboratory Research
Allergy and Clinical Immunology Branch
(304) 285-6024