EXPRESSÃO DE GENES DO SISTEMA RENINA ANGIOTENSINA EM CÉLULAS EPITELIAIS DA BOCA E DE SANGUE VENOSO PERIFÉRICO EM PORTADORES DE FIBRODISPLASIA OSSIFICANTE PROGRESSIVA, E SUA MODULAÇÃO PELO ÁCIDO ASCÓRBICO E PROPRANOLOL

Abstract

Fibrodysplasia Ossificans Progressiva (FOP) is an ultra-rare and untreatable disease resulting from a gain-of-function mutation in the ACVR1 gene (c.617G>A, p.R206H). Recently understood as an inflammatory disease, there are still gaps in the clarification of factors directly or indirectly involved in inflammation and ectopic bone formation. With an innovative approach, the relative mRNA expression of six target genes of the Renin Angiotensin System (RAS) encoding ACE, ACE2, AGTR1, AGTR2, MAS1 and MRGD were investigated in oral epithelial cells and peripheral blood cells (total leukocytes). Representing pathways related to that system, the following were investigated: TNF-α, RUNX2, ADRB1, ADRB2, NFKB1 (p50), RELA (p65) and VEGF-A. Gene expression studies and their modulation by ascorbic acid and propranolol were performed in three groups – control, FOP patients without treatment, and FOP patients treated with ascorbic acid + propranolol (FOPCON) –, based on total RNA extraction followed by reverse transcription and real-time qPCR. The expression of RAS genes in oral epithelial cells of FOP patients was demonstrated for the first time, strengthening the viability of this specimen for research purposes. Here, the RAS target genes investigated did not characterize the phenotypic marker profile of FOP in the analyzed tissues. However, the mild modulation of these genes suggests a supporting role for this system in the anti-inflammatory, antifibrotic and antinociceptive processes in response to the continuous use of ascorbic acid and propranolol. Among the findings, the downregulation of AGTR1, AGTR2 and MRGD in oral epithelial cells was simultaneous to the downregulation (normalization) of TNF-α and ADRB2, overexpressed in epithelial cells of untreated FOP patients, without significant influence on RUNX2. Modulation of MRGD at the tissue level suggests regulation of the inflammatory pathway involved in pain sensation and transduction, which could not be confirmed by the study of the NF-kB pathway in total leukocytes from peripheral blood. Compared with the basal state of FOP, there was no significant regulation of MAS1 in epithelial cells in response to treatment, while in total leukocytes, treatment induced the upregulation of ACE2 and MAS1, simultaneous to the upregulation of ACE and AGTR1. The responses of MAS1 and MRGD encourage further clarification regarding the usefulness of adding peptides suggested as anti-inflammatory to the treatment. A short interruption of the medication was not sufficient to achieve a wash-out effect, but suggests a residual protective effect of the treatment, through the perpetuation of the modulation in the gene expression of the RAS receptors and TNF-α, obtained with the treatment. In addition, clinical evaluation data regarding adverse effects and functionality are briefly described. Further clarification of the mechanisms of action of ascorbic acid and propranolol in controlling the disease, and how the functional genomic equalization of the RAS can support it, is still necessary.