Role of the Fungus Pneumocystis in IL1β Pathway Activation and Airways Collagen Deposition in Elastase-Induced COPD Animals

Inflammation and mucus production are prevalent characteristics of chronic respiratory conditions, such as asthma and chronic chronic obstructive pulmonary disease (COPD). Biological co-factors, including bacteria, viruses, and fungi, may exacerbate these diseases by activating various pathways associated with airway diseases. An example is the fungus , which is linked to severe COPD in human patients. Recent evidence has demonstrated that significantly enhanced inflammation and mucus hypersecretion in a rat model of elastase-induced COPD. The present study specifically aims to investigate two additional aspects associated with the pathology induced by infection: inflammation and collagen deposition around airways. To this end, the focus was to investigate the role of the IL-1β pro-inflammatory pathway during infection in COPD rats. Several airway pathology-related features, such as inflammation, mucus hypersecretion, and fibrosis, were evaluated using histological and molecular techniques. COPD animals infected with exhibited elevated inflammation levels, including a synergistic increase in IL-1β and Cox-2. Furthermore, protein levels of the IL-1β-dependent transcription factor cAMP response element-binding (CREB) showed a synergistic elevation of their phosphorylated version in the lungs of COPD animals infected with , while mucus levels were notably higher in the airways of COPD-infected animals. Interestingly, a CREB responsive element (CRE) was identified in the Muc5b promoter. The presence of CREB in the Muc5b promoter was synergistically increased in COPD animals infected with compared to other experimental groups. Finally, an increment of deposited collagen was identified surrounding the airways of COPD animals infected with compared with the other experimental animal groups and correlated with the increase of mRNA levels. These findings emphasize the role of as a potential biological co-factor in chronic respiratory diseases like COPD or asthma, warranting new perspectives in the treatment of chronic respiratory diseases.