Vitamin D3 preserves blood retinal barrier integrity in an in vitro model of diabetic retinopathy.

The impairment of the blood retinal barrier (BRB) represents one of the main features of diabetic retinopathy, a secondary microvascular complication of diabetes. Hyperglycemia is a triggering factor of vascular cells damage in diabetic retinopathy. The aim of this study was to assess the effects of vitamin D3 on BRB protection, and to investigate its regulatory role on inflammatory pathways. We challenged human retinal endothelial cells with high glucose (HG) levels. We found that vitamin D3 attenuates cell damage elicited by HG, maintaining cell viability and reducing the expression of inflammatory cytokines such as IL-1ß and ICAM-1. Furthermore, we showed that vitamin D3 preserved the BRB integrity as demonstrated by trans-endothelial electrical resistance, permeability assay, and cell junction morphology and quantification (ZO-1 and VE-cadherin). In conclusion this in vitro study provided new insights on the retinal protective role of vitamin D3, particularly as regard as the early phase of diabetic retinopathy, characterized by BRB breakdown and inflammation.

Somatic mosaicism with reversion to normality of a mutated transthyretin allele related to a familial amyloidotic polyneuropathy.

Familial amyloidotic polyneuropathy (FAP) is a progressive neuropathy, with onset in adulthood and high mortality. It is related to an altered transthyretin (TTR) plasma protein, mainly produced by the liver and responsible for amyloid deposit in the peripheral nervous system. SNPs in the TTR gene were associated with FAP, and the G>C substitution (NM_000371.3:c.325G>C) in the 109th codon (GAG vs CAG; NP_362.1:p.E109Q) was previously described in Sicily (Italy). Here, we report on a Sicilian family with several patients affected by FAP related to the E109Q mutation, which displayed a somatic mosaicism with the reversion to normality of the c.325G>C mutation. After exclusion of isodisomy and allele deletion, this event seems to be due to a rare, post-zygotic interallelic gene conversion with the wild-type allele serving as a donor. Further investigations will be necessary to better understand the molecular basis of this phenomenon, and could help determine if this can be induced in a targeted manner in the context of natural gene therapy to treat TTR-related FAP patients, as previously proposed for other diseases. Moreover, our results confirm the need to perform DNA-based diagnostic tests with at least a second tissue when a suspected germline mutation in a candidate gene is not identified in the first tissue.