Effects Of Administering All-trans Retinoic Acid To Hoxa1^+/- Pregnant Sows On Lung Development Of Hoxa1^-/-Fetal Pigs

Hoxa1 plays an important role in the embryonic development of mammals.The purpose of this study was to study the effects of supplementation of all-trans retinoic acid（ATRA）to pregnant sows on the lung development of Hoxa1 mutant fetal pigs.Provide reference for the treatment of HOXA1 syndrome.One Hoxa1^+/-boar was mated with 9 Hoxa1^+/-sows.9pregnant sows were randomly divided into 1 control group（n=3）and 3 experimental groups（n=2 in each group）.The sows in the control group were fed with basal diet,and the sows in groupsⅠ,ⅡandⅢwere fed with all-trans retinoic acid（ATRA）on the 12th,13th and 14th day after breeding,respectively.The samples of lung tissue were collected from newborn Hoxa1 mutant(Hoxa1^-/-)and non-mutant Hoxa1piglets that delivered by sows in control group and newborn Hoxa1 mutant piglets that delivered by sows in experimental groups.The effects of all-trans retinoic acid supplementation on the lung development of Hoxa1 mutant fetal pigs were studied by HE staining,immunofluorescence,fluorescent quantitative PCR,immunohistochemistry,Western blot,enzyme-linked immunosorbent assay and transcriptome analysis.The results showed that:1.Compared with the non-Hoxa1 mutant piglets in the control group,the Hoxa1 mutant piglets in control group had the significantly increased thickness of alveolar septum（P<0.01）,the decreased alveolar surface（P<0.01）,the reduced number of typeⅠalveolar epithelial cells,the increased number of typeⅡalveolar epithelial cells,the lower expression of FGFR1OP（P<0.05）and COL4A4（P<0.01）.Compared with the Hoxa1 mutant piglets from control group,the Hoxa1 mutant piglets from experimental group III had the thicker alveolar septum（P<0.01）,the increased alveolar surface（P<0.01）,the increased expression of WNT2,FGFR4,FGFR1OP,RXRG,RARRES1 and COL4A4（P<0.01）.2.Compared with the non-Hoxa1 mutant piglets in the control group,the Hoxa1 mutant piglets in control group had the significantly decreased immunohistochemical IOD value of v WF（P<0.01）and the decreased expression of angiogenesis-related genes FIGF,PDGFD,KDR and NEDD4（P<0.01）,the increased expression of angiogenesis repression gene FOXO3（P<0.05）.Compared with the Hoxa1 mutant piglets from control group,the Hoxa1 mutant piglets from experimental group III had the significantly increased IOD value of v WF（P<0.01）,the increased expression of FIGF,PDGFD,KDR,ID1 and NEDD4（P<0.01）,the decreased expression of FOXO3（P<0.01）and the increased expression of angiogenesis-related proteins VEGFR2,ALDH1A1 and VEGFA（P<0.01）.3.Compared with the non-Hoxa1 mutant piglets in the control group,the Hoxa1 mutant piglets in control group had the significantly decreased content of IFN-γ（P<0.05）and the increased expression of immunosuppression related gene TGFBR1（P<0.0l）.Compared with the Hoxa1 mutant piglets from control group,the Hoxa1 mutant piglets from experimental group III had the significantly increased content of IFN-γ（P<0.01）and decreased expression of TGFBR1（P<0.01）.4.The results of transcriptional group showed that there were 828 up-regulated differentially expressed genes and 2848 down-regulated differentially expressed genes in the lung tissue of Hoxa1 mutant piglets in the control group compared with the control group.Compared with the control group,there were 2941 up-regulated differentially expressed genes and 1137 down-regulated differentially expressed genes in the lung tissue of Hoxa1mutant piglets in groupⅢ.Summary:（1）Supplementary feeding of Hoxa1^+/-pregnant sows with all-trans retinoic acid promotes the development of Hoxa1^-/-fetal porcine alveoli and capillaries,and improves the genes expression related to the synthesis of retinoic acid and immune function.（2）Hoxa1^+/-pregnant sows fed with 4mg/kg body weight all-trans retinoic acid on the fourteenth day after mating have the best effect on the development of Hoxa1^-/-fetal lungs.