Background A significant percentage of genetic and inflammatory diseases derive from splicing alterations. Therefore, the understanding of what modifications in spliceosome determine an alternative splicing and its association with the development of such pathologies is of critical importance.
Objectives To identify the alterations present in the spliceosome machinery of patients with rheumatoid arthritis (RA),its influence on the development and activity of the disease and their atherothrombotic profile.
Methods An array of selected components of the major- (n=12) and minor-spliceosome (n=4) and associated splicing factors (n=28) was developed, and their expression levels were evaluated using a Fluidigm methodology, in purified leukocytes from 14 RA patients and 14 healthy donors (HD). In parallel, an extensive clinical/serological evaluation was performed. Carotid intimate media thickness (CIMT) was used as atherosclerosis marker. Endothelial activity was monitored by laser-doppler flowmetry, and pro-inflammatory and oxidative stress markers were quantified. Association of these splicing components with clinical and analytical features were investigated.
Results A significant alteration in various components of spliceosome and splicing factors was found in all the leukocytes subtypes from RA patients vs HD. Interestingly, we found a specific altered profile of splicing factors and spliceosome components when compared monocytes (CA150, PRP8, SRM160, U2AF1, RNU4atac, PTBB1, RAVER1, RBM17, SRSF4, SRSF10), lymphocytes (RNU12, RNU4, RNU6, PRP8, MAGOH, NOVA1, SRSF3) and neutrophils (RNU11, RNU6, SC35, RBM3).
Altered levels of various spliceosome elements in monocytes were associated with the presence of atheromatous plaques, while in neutrophils were found related to radiological involvement. In lymphocytes, the alteration of these components were linked to the positivity for Rheumatoid Factor and anti-CCPs antibodies, indicating that modifications in the spliceosome machinery could contribute to the increase in the production and assembly of autoantigens, inducing autoantibody production.
Correlation studies showed a significant relationship between altered levels of various spliceosome components in different leukocyte subtypes and high disease activity (DAS, HAQ), increased expression of proinflammatory mediators (CRF, TF, TNF, IL-8, TLR4) and oxidative stress markers (peroxides, GPX, SOD)as well as with parameters associated with insulin resistance.
Conclusions These results reveal that there is a significant alteration of spliceosome components in RA patients that could be associated with the development and activity of this autoimmune condition, and influence mechanisms that drive the development of cardiovascular disease. Studies in progress will help to clarify the physiological implications of these findings, which could constitute new diagnostic biomarkers, as well as new therapeutic tools for the treatment of RA.
Acknowledgements Funded by CTS7940, and ISCIII (PI15/01333, CP15/00158, and RIER RD16/0012/0015).
Disclosure of Interest None declared