OBJECTIVETo study the effect of 1,25-(OH)2D3 supplementation during gestation and lactation on TGF-β1 and Smad3 expression in lungs of rat offspring with asthma.

METHODSThirty-two female Wistar rats were randomly divided into four groups: low-, medium- and high-dose 1,25-(OH)2D3 supplementation and control groups (n=8 each). From the 7th day of gestation, the three 1,25-(OH)2D3 supplementation groups were administered with 2,10 and 20 μg/mL of 1,25-(OH)2D3 respectively every other day until weaning (rat offspring: 21 days old). The control group received normal saline instead. Then, bronchial asthma was induced in rat offspring from the 4 groups. The protein and mRNA expression of TGF-β1 and Smad3 in the lung tissue was measured by immunochemistry and RT-PCR.

RESULTSEosinophil cell infiltration and airway inflammation decreased in rat offspring from the low- and medium-dose 1,25-(OH)2D3 groups, but increased in rat offspring of the high-dose 1,25-(OH)2D3 group compared with the control group. Immunohistochemistry of lung tissues showed that the expression of TGF-β1 protein and pSmad3 decreased in rat offspring from the low- and medium-dose 1,25-(OH)2D3 groups (P<0.05), but increased significantly in rat offspring from the high-dose 1,25-(OH)2D3 group compared with the control group (P<0.05). PCR showed that the expression of TGF-β1 and Smad3 mRNA in the lung tissue decreased in rat offspring from the low- and medium-dose 1,25-(OH)2D3 groups (P<0.05), but increased significantly in rat offspring from the high-dose 1,25-(OH)2D3 group compared with the control group (P<0.05).

CONCLUSIONS1,25-(OH)2D3 supplementation plays a role in regulating the immune system in asthmatic rats. Its mechanism may be associated with regulation of the expression of TGF-β/Smad signal pathway-related proteins through the vitamin D receptor signal pathway.