Our sensitivity analysis shows that a set of parameters including k13, k14, k15, and dTD have relatively large PRCCs (>0.1, Figure A in S1 File), suggesting that TD outcomes are sensitive to these parameters. This set of parameters, whose values can be changed from individual to individual, are associated with different network elements, positive feedback loops and pathways, which are critical in the CS-induced immune response and COPD progression. Therefore, investigation of model outcome changes with variations in these parameters can be of great use to disclose the cellular and molecular mechanisms of COPD as discussed below.