OBJECTIVETo investigate the effect of vitamin D on the expression of chemokine regulated on activation, normal T cells expressed and secreted (RANTES) in the lung tissue of asthmatic rats, and the role of vitamin D in the control of asthmatic airway inflammation and the synergistic action of hormones.

METHODSForty female Wistar rats were randomly and equally divided into normal control, asthma, vitamin D intervention, budesonide intervention, and budesonide+vitamin D intervention groups. Hematoxylin and eosin staining was used to observe pathological changes in the lung tissue. Immunohistochemistry was used to measure the protein expression of RANTES in lung tissue. Enzyme-linked immunosorbent assay was used to measure the level of RANTES in bronchoalveolar lavage fluid (BALF). Real-time quantitative PCR was used to measure the mRNA expression of RANTES.

RESULTSThe asthma group showed the most significant pathological changes in the lung tissue, including inflammatory cell infiltration, bronchial stenosis and distortion and smooth muscle rupture, while the intervention groups showed fewer pathological changes. Of the intervention groups, the budesonide intervention group showed fewer pathological changes than the vitamin D intervention group, and the budesonide+vitamin D intervention group showed the mildest pathological changes, which were similar to those observed in the normal control group. Protein expression of RANTES in the lung tissue and BALF was significantly higher in the asthma group than in the normal control group (P<0.05), while it was lower in the intervention groups than in the asthma group, exhibiting significant differences between each intervention group and the asthma group (P<0.05) (except the difference in protein expression of RANTES in BALF between the vitamin D intervention and asthma groups). The budesonide+vitamin D intervention group showed less protein expression of RANTES in the lung tissue and BALF than both the budesonide intervention and vitamin D intervention groups (P<0.05). The mRNA expression of RANTES was significantly higher in the asthma group than in the normal control group (P<0.05), while it was significantly lower in three intervention groups than in the asthma group (P<0.05), however no significant difference was found between the intervention groups in this regard. The budesonide+vitamin D intervention group showed the lowest level of RANTES mRNA, with no significant difference from the normal control group.

CONCLUSIONSThe mRNA and protein expression of RANTES in BALF and lung tissue increases significantly in asthmatic rats. Vitamin D intervention can decrease the expression of RANTES, suggesting that vitamin D can reduce airway inflammation by regulating the expression of RANTES. Vitamin D can be used together with budesonide to further decrease the mRNA and protein expression of RANTES.