The bile acid-activated retinoic acid response in dendritic cells is involved in food allergen sensitization

BACKGROUND

Alteration of commensal microbiota is highly correlated with the prevalence of allergic reactions to food in the gastrointestinal tract. The mechanisms by which microbiota modulate food allergen sensitization in the mucosal site are not fully understood.

METHODS

We generate DCs specific knockout of retinoic acid receptor α (Rara) gene mice (DC KO Rara) to evaluate food sensitization. The bile acid-activated retinoic acid response was evaluated by flow cytometry, real-time RT-PCR and Illumina transcriptome sequencing. The global effect of Abx treatment on BA profiles in the mucosal lymph tissue mLN in mice was examined by UPLC-MS analysis.

RESULTS

In this study, we demonstrate that depletion of commensal gut bacteria leads to enhanced retinoic acid (RA) signaling in mucosal dendritic cells (DCs). RA signaling in DCs is required for the production of food allergen-specific IgE and IgG1. Antibiotics induced an enlarged bile acid (BA) pool, and dysregulated BA profiles contributed to enhanced RA signaling in mucosal DCs. BA-activated RA signaling promoted DC upregulation of interferon I signature, RA signature, OX40L, and PDL2, which may lead to T helper 2 differentiation of CD4+ T cells. BA-activated RA signaling involved the farnesoid X receptor and RA receptor α (RARa) interaction. Depletion of bile acid reduces food allergen specific IgE and IgG1 levels in mice.

CONCLUSION

Our research unveils a mechanism of food sensitization modulated by BA-RA signaling in DCs, which suggests a potential new approach for the intervention of food allergic reactions.

Retinoid X Receptor Antagonists

Retinoid X receptor (RXR) antagonists are not only useful as chemical tools for biological research, but are also candidate drugs for the treatment of various diseases, including diabetes and allergies, although no RXR antagonist has yet been approved for clinical use. In this review, we present a brief overview of RXR structure, function, and target genes, and describe currently available RXR antagonists, their structural classification, and their evaluation, focusing on the latest research.

Omics in Zebrafish Teratogenesis

The genome revolution represents a complete change on our view of biological systems. The quantitative determination of changes in all major molecular components of the living cells, the "omics" approach, opened whole new fields for all health sciences. Genomics, transcriptomics, proteomics, metabolomics, and others, together with appropriate prediction and modeling tools, will mark the future of developmental toxicity assessment both for wildlife and humans. This is especially true for disciplines, like teratology, which rely on studies in model organisms, as studies at lower levels of organization are difficult to implement. Rodents and frogs have been the favorite models for studying human reproductive and developmental disorders for decades. Recently, the study of the development of zebrafish embryos (ZE) is becoming a major alternative tool to adult animal testing. ZE intrinsic characteristics makes this model a unique system to analyze in vivo developmental alterations that only can be studied applying in toto approaches. Moreover, under actual legislations, ZE is considered as a replacement model (and therefore, excluded from animal welfare regulations) during the first 5 days after fertilization. Here we review the most important components of the zebrafish toolbox available for analyzing early stages of embryotoxic events that could eventually lead to teratogenesis.

One-dimensional proteomic profiling of Danio rerio embryo vitellogenin to estimate quantum dot toxicity

BACKGROUND

Vitellogenin (Vtg) is the major egg yolk protein (YP) in most oviparous species and may be useful as an indicator in ecotoxicological testing at the biochemical level. In this study, we obtained detailed information about the Vtgs of Danio rerio embryos by cutting SDS-PAGE gel lanes into thin slices, and analyzing them slice-by-slice with (MALDI-TOF) mass spectrometry.

RESULTS

We conducted three proteomic analyses, comparing embryonic Danio rerio Vtg cleavage products after exposure for 48 h to CdSecore/ZnSshell quantum dots (QDs), after exposure to a mixture of the components used for quantum dot synthesis (MCS-QDs), and in untreated embryos. The Vtg mass spectrometric profiles of the QDs-treated embryos differed from those of the unexposed or MCS-QDs-treated embryos.

CONCLUSION

This study demonstrates the possible utility of Vtg profiling in D. rerio embryos as a sensitive diagnostic tool to estimate nanoparticle toxicity.