Prävention von Lippen-Kiefer-Gaumen-Spalten

New molecular aspects in the mechanism of oromaxillofacial cleft prevention by B-vitamins

Clinical and experimental studies show a clear positive effect of B-vitamins in the prevention of oromaxillofacial clefts, especially cleft lip and palate (CL/P). Hereby the local effect of thiamin (B1) in the amniotic fluid is very important for the embryonic facial development as seen in palatal organ models stimulated by topical B-vitamin application (Scheller et al., 2013a). Moreover a low B1 concentration in the serum and amniotic fluid was found in pregnant mice with clefts in their offspring (Scheller et al., 2013b). Immunochemical analyses of midface sections (ThTr-1 transporter) and the placenta (ThTr-2 transporter) of cleft fetuses with orofacial clefts showed an atypical cytoplasmatic localization (Scheller et al., 2017). mRNA nalyses of different B-vitamin transporters (B1, B2, B5, B7, B9) were performed and showed ThTr2 transporter in a short splice variant in all cleft fetuses. This splice variant may cause a functional loss of the transport capacity through the placenta barrier and result in a low amniotic fluid concentration of vitamin B1. All other analyzed transport proteins showed no functional change. These findings confirm the hypothesis that cleft prevention by high vitamin B1 substitution fails in genetically determined cleft mice, caused by an insufficient B1 uptake and missing local effect.

Sex distribution is a factor in teratogenically induced clefts and in the anti-teratogenic effect of thiamine in mice, but not in genetically determined cleft appearance

PURPOSE

Cleft lip and/or palate (CL/P) shows a gender-related distribution in human beings. The reason is unknown. This study analyzed the gender-related cleft appearance with respect to teratogenically and genetically determined cleft appearance and the response to thiamine (vitamin B1) supplementation.

MATERIAL AND METHODS

Cyclophosphamide (CPA; 0.6 mg) and dexamethasone (0.25 mg) were injected intraperitoneally to A/B-Jena mice on different days of pregnancy. The abortion and malformation rate in the A/B-Jena and A/WySn mice with genetically determined clefting was documented to be gender-specific. Vitamin B1 was given to A/B-Jena dams at different times during pregnancy before, simultaneously and after the teratogenic agent was given to the pregnant mothers. A/WySn mice received oral supplementation at different times during embryonic/fetal development.

RESULTS

There were significantly more living female fetuses when mothers were treated with teratogens, and the embryo lethality and malformation affected more male individuals. However, the survival and malformation rate in A/WySn mice was not gender-specific. Especially in male fetuses, vitamin B1 decreased the teratogenic cleft rate (CPA: p < 0.001, dexamethasone: p = 0.6), whereas there was no effect in the A/WySn mice.

CONCLUSION

There was a strong anti-teratogenic effect of vitamin B1, especially in the male fetuses. Genetically determined cleft appearance was not positively influenced. These findings confirm observations about cleft appearance in human beings.

Lower concentrations of B-vitamin subgroups in the serum and amniotic fluid correlate to cleft lip and palate appearance in the offspring of A/WySn mice

PURPOSE

The pathogenesis and prevention of cleft lip and palate (CL/P) have been studied mainly in clinical and animal experiments. A prophylactic poly-B-vitamin substitution during the first months of pregnancy has provided the most encouraging results for the prevention of CL/P recurrence in families at risk. In vitro studies of the palatal organ in an A/WySn mouse model have confirmed the positive influence of B-vitamins on palatal development. The present animal study was performed to analyze different B-vitamin concentrations in the serum and amniotic fluid of A/WySn mice according to the appearance of CL/P in their offspring.

MATERIAL AND METHODS

Concentrations of different B-vitamins (B1, B2, B3, B5, B6, and folic acid) in serum and amniotic fluid were analyzed by high-performance liquid chromatographic detection. Immunohistochemical staining against thiamin-1 receptor was performed on histologic midface sections of A/WySn fetuses with (n = 12) and without (n = 14) CL/P.

RESULTS

Vitamin B5 (P < .001) and folic acid (P < .004) concentrations in the amniotic fluid of dams with CL/P were significantly lower than in dams without CL/P. Serum concentrations of folic acid (P = .5) and B5 (P = .4) showed no difference between the 2 groups. Dams with CL/P had significantly lower thiamine concentrations in serum (P = .01) and amniotic fluid (P < .001). Histologic midface sections presented high thiamin-1 receptor expression in the palatal shelf of fetuses with CL/P.

CONCLUSION

A decreased use or uptake of some B-vitamin subgroups (B1, B5, and folic acid) in amniotic fluid and serum (vitamin B1) was correlated to an increased cleft appearance in A/WySn mice. The high thiamin-1 receptor expression in the palatal tissue of mouse fetuses with CL/P may be caused by a decreased availability of vitamin B1.

Perturbation of Fgf10 signal pathway in mouse embryonic palate by dexamethasone and vitamin B12 in vivo

BACKGROUND/PURPOSE

The Fgf10 signaling pathway plays an important role in early stages of mouse embryonic palatal development, which is associated with cell proliferation and differentiation. The objective of this study was to assess whether dexamethasone and vitamin B(12) affected the Fgf10 signal pathway of mouse embryonic palate.

MATERIALS AND METHODS

Immunohistochemical studies were performed for expression of Fgf10, Fgfr2b, and sonic hedgehog and for cell proliferation and apoptosis of mouse embryonic palate.

RESULTS

The expression of Fgf10, Fgfr2b, and sonic hedgehog was changed in mouse embryonic palate after dexamethasone and vitamin B(12) treatment, resulting in reduced and restored proliferation of mesenchymal cells.

CONCLUSIONS

Dexamethasone and vitamin B(12) affected the Fgf10 signaling pathway and cell proliferation of mouse embryonic palate. Cell apoptosis was not altered after dexamethasone and vitamin B(12) exposure.