RESUMEN
BACKGROUND: Natural products have a prime importance as an essential source for new drug discovery. Carica papaya leaves (CPL) have been used to treat inflammation in traditional system of medicine. AIM/HYPOTHESIS: Current study evaluates the anti-inflammatory and immunomodulatory effects of CPL extract using mouse model of ovalbumin- (OVA) induced allergic asthma. METHODS: All the mice were intraperitoneally sensitized and subsequently given intranasal challenge with OVA except the control group. Group-III and -IV were treated for seven consecutive days with CPL extract and methylprednisolone (MP), respectively. At the end of study, histopathological examination of the lungs was performed and inflammatory cell counts were done in blood as well as bronchoalveolar lavage fluid (BALF). The mRNA expression levels of IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS were measured using reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Results showed significant attenuation of lung infiltration of inflammatory cells, alveolar thickening, and goblet cell hyperplasia after treatment with CPL extract. We also found significant suppression of total and differential leukocyte counts in both blood and BALF samples of CPL extract treated group. CPL extract also alleviated the expression levels of IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS. Similarly, treatment with MP, used as a reference drug, also significantly ameliorated all the pro-inflammatory markers. CONCLUSION: Current study shows that CPL extract possesses anti-inflammatory effect in mouse model of allergic airway inflammation by down-regulating IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS expression levels.