Similar results were obtained by varying k14 and k15 shown in Figures D-E in S1 File, respectively. Intriguingly, the changes in some parameters such as kI6,M1 in Eq 10, which do not affect directly on the TD outcome, also lead to similar results for TD dynamics, shown in Figure F in S1 File. Here, our modeling results demonstrate that similar TD outcomes can result from variations of different parameters. As will be discussed later, these parameters may be associated with different mechanisms of CS-induced immune responses in COPD progression, implying that similar COPD phenotypes can be caused by different mechanisms (endotypes). This finding could be important for developing therapeutic methods to treat COPD, as also discussed below.