Abstract: Objective To investigate the effect of chloroquine on airway hyperresponsiveness in asthmatic mice and explore the
possible mechanism. Methods Balb/c mouse models of asthma established using OVA received intraperitoneal injections of
chloroquine, dexamethasone, or both prior to OVA challenge. Within 24 h after the final challenge, airway hyperresponsiveness
(AHR) of the mice was assessed, and the total cell count and the counts of different cell populations in the
bronchoalveolar lavage fluid (BALF) were determined under light microscopy. The severity of lung inflammation was
evaluated using HE staining, and the concentrations of IL-6 and PGF2α in the BALF were detected by enzyme-linked
immunosorbent assay (ELISA). Results Chloroquine pretreatment significantly decreased AHR (P<0.001) in the asthmatic mice
and reduced the total cell count (P<0.01), eosinophils (P<0.001), neutrophils (P<0.01), and PGF2α levels in the BALF.
Chloroquine combined with low-dose dexamethasone significantly lessened inflammations around the bronchioles (P<0.05)
and blood vessels (P<0.01) in the lung tissue, and obviously lowered IL-6 (P<0.05) and PGF2α (P<0.001) in the BALF in the
asthmatic mice. Conclusion Chloroquine can inhibit AHR in asthmatic mice and produce better anti-inflammatory effect when
combined with dexamethasone for treatment of neutrophilic asthma.