Glucocorticoids (GCs) exert a
therapeutic effect in numerous chronic inflammatory diseases. However,
chronic obstructive pulmonary disease (
COPD) tends to be GC-resistant.
Icariin, a major component of
flavonoids isolated from Epimedium brevicornum Maxim (Berberidaceae), significantly relieves symptoms in patients with
COPD. However, the mechanism of action remains unclear and further investigation is required to establish whether it may serve as an alternative or complementary
therapy for
COPD. The aim of the present study was to determine the effects of
icariin in human bronchial epithelial cells exposed to cigarette
smoke extract (CSE) and to determine whether
icariin reverses GC resistance. The results revealed that
icariin significantly increased the proliferation of CSE-exposed cells. Furthermore,
icariin significantly increased
protein expression of the anti-inflammatory factor
interleukin (IL)-10 and significantly decreased
protein expression of the pro-inflammatory factors
IL-8 and
tumor necrosis factor α.
Icariin also attenuated the expression of the cellular matrix remodelling
biomarkers matrix
metallopeptidase 9 and
tissue inhibitor of metalloproteinase 1, and decreased the production of
reactive oxygen species (ROS). In addition,
icariin regulated the expression of GC resistance-related factors, such as GC receptors,
histone deacetylase 2, nuclear factor erythroid-2-related factor 2 and nuclear factor κ B. The results obtained in the present study suggested that
icariin may decrease CSE-induced
inflammation,
airway remodelling and ROS production by mitigating GC resistance. In conclusion,
icariin may potentially be used in combination with GCs to increase therapeutic efficacy and reduce GC resistance in
COPD.