Anti-inflammatory immunomodulation for the treatment of Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is a rare disease where the diaphragm does not develop properly altering lung development with no established therapy. We have analyzed the effect of anti-inflammatory immunomodulators that influence macrophage activation in animal CDH models. In the widely-used nitrofen-induced model of CDH in pregnant rats, administration of a single dose of atypical Toll-like Receptors TLR2/4 dual ligands (CS1 and CS2), 3 days after nitrofen, cured diaphragmatic hernia in 73 % of the fetuses, repaired the lesion with complete diaphragm closure. Moreover, they also improve pulmonary hypoplasia and vessel hypertrophy, enhancing pulmonary maturity of fetuses. CS1 treatment also rescued the CDH phenotype in the G2-GATA4Cre;Wt1fl/fl CDH genetic mice model. Only 1 out 11 mutant embryos showed CDH after CS1 administration, whereas CDH prevalence was 70% in untreated mutant embryos. Mechanistically, CS1 stimulated the infiltration of repairing M2 macrophages (CD206+ and Arg1+) into the damaged diaphragm and reduced T cell infiltration. Alteration in retinoic acid pathways a have been also implicated in the etiology of CDH. TLR2/4 dual ligands also induced retinol pathway genes, including RBP1, RALDH2, RARα and RARβ, in the affected lungs and the diaphragm and in macrophages in vitro . The present results place atypical TLR2/4 ligands as a promising solution for CDH, where the own immune system of the fetus is responsible for repairing the hernia/damage in the diaphragm, ensuring the correct positioning and development of all organs. ### Competing Interest Statement The authors have declared no competing interest.