Asthma, COPD, the "asthma-COPD" syndrome and severe asthma - relatives or "incidental strangers"?

Objective: Airways obstructive diseases (asthma, COPD, asthma-COPD overlap (ACO) and severe asthma) are different entities characterized by airflow obstruction. They may share common pathogenetic mechanisms allowing new therapeutic options for patients.
Methods: A review of the current literature is performed to investigate the common pathogenetic mechanisms among these medical conditions.
Results: Different specific cytokones are involved in both asthma and COPD pathogenesis, while ACO shares some of these cytokines placing the condition between the two entities. The cytokines regulate accumulations and contraction of airways smooth muscle cells which leads to different expression of airflow obstruction. A special cytokine, TSLP, is highlighted as playing a key role in the pathogenesis of asthma, COPD, ACO, and severe asthma which opens the opportunity for new treatment options for patients suffering from these conditions.
Conclusion: COPD, asthma, ACO and severe asthma share some common elements in their pathogenesis which opens the gate for new therapeutic options for the patients