Background: Asthma is a chronic inflammatory disease affecting smaller airways. Airflow obstruction leading to airway hyper-responsiveness and increased mucus production are salient features of asthma pathophysiology. Generally, Th2 cytokines are increased in allergic asthma.

Aim: To propose the molecular mechanisms by which Carica Papaya Leaves Extract (CPLE) alleviates pulmonary edema in animal model of allergic airway inflammation comparable to methylprednisolone.

Place and duration of study: Pharmacology Department, University of Health Sciences Lahore for 1 year.

Methods: We took twenty four male BALB/c mice and divided them equally into four groups. The control group was given PBS only, while Group II served as diseased group and induced airway inflammation by ovalbumin. Group III and IV were first induced with airway inflammation and  side by side treated with Carica papaya leaf extract (CPLE) 100mg/kg body weight orally and methylprednisolone 15 mg/kg body weight intraperitoneally for seven consecutive days respectively. At the end of the experimental protocol, mice were euthanized and lung wet/dry ratio was measured. mRNA expression of AQP1 and AQP5 in lung tissue were also determined using RT-PCR.

Results: Ethanolic extract of Carica Papaya leaves decreased all markers of pulmonary edema in mouse model of allergic airway inflammation comparable to methylprednisolone by decreasing lung wet/dry ratio and enhancing AQP1 and AQP5 mRNA expression.

Conclusion: Carica Papaya leaves extract may diminish pulmonary edema in mice associated with allergic asthma.

Keywords: AQP1, AQP5 (Aquaporins), Carica Papaya Leaves Extract (CPLE), Pulmonary Edema, Th2 cytokines.