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A6237 - Mechanical Forces Suppress Innate Anti-Viral Immunity in Primary Human Airway Epithelial Cells Obtained from Asthma Donors
Author Block: P. Veerati1, N. W. Bartlett2, K. Nichol1, P. A. B. Wark3, D. A. Knight2, C. L. Grainge3; 1Respiratoty, Hunter Medical Research Institute, New Lambton Heights, Australia, 2Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia, 3Respiratory and Sleep Medicine, John Hunter Hosp, New Lambton NSW 2322, Australia.
Rationale:
Asthma is characterized by airway inflammation and episodic bronchoconstriction (BC) leading to clinical symptoms and generation of mechanical forces within the airway. Exacerbations of asthma are most commonly caused by viral infection (especially rhinovirus (RV)). During exacerbations, BC and viral infection occur simultaneously; these factors may interact in the airway. We hypothesized that mechanical forces generated during BC suppress airway innate anti-viral immunity. To investigate this, we exposed air-liquid interface (ALI) cultures of primary human bronchial epithelial cells (pBECs) to mechanical forces mimicking BC either before or during a physiologically relevant RV infection. We then examined the effect of mechanical forces occurring prior to infection (mimicking poor asthma control), or during viral infection (mimicking virally induced BC).
Methods:
pBECs from asthmatic donors were obtained at bronchoscopy, cultured and differentiated at ALI. Cells were apically compressed using 5% CO2 in air at 30cm H20 pressure in two different models. In the ‘poor control model’ we applied apical compression for 10 minutes every hour for 4 days prior to viral infection. The ‘exacerbation model’ applied the same apical compression regime from 6 hours following viral infection. In each case, cultures were infected with RV serotype 1B (RV1B) at a multiplicity of infection (MOI) of 0.001. Samples were collected at 0, 24, 48, 72 and 96 hours following infection and were analysed for viral RNA, TCID50, interferon beta (IFN-β) and lambda (IFN-λ) mRNA and protein as well as Muc5AC, TGF-β2 and IL-8 protein.
Results:
Compression suppressed the release of IFN-β and IFN-λ protein following RV1B infection from 48 hours in both the exacerbation and poor control models. In the exacerbation model, at 96 hours post infection, IFN-β release with virus alone ((Mean±SD): 253±241 pg/ml), was decreased with the addition of compression (60±32 pg/ml). Similar results were obtained with IFN-λ; virus alone: 749±475 pg/ml, compression+virus: 149±41 pg/ml. Compression did not alter viral replication. Similar findings were observed in the poor control model.
Conclusion:
We demonstrate that mechanical forces similar to those induced during BC in vivo impair innate anti-viral immunity in pBECs, whether the force is applied prior to viral infection or following infection. This is the first time that mechanical forces have been shown to impact on innate immunity
and may explain why poorly controlled asthmatics have impaired anti-viral immunity which can be improved with better disease control.