POS0419 ABERRANT SPLICEOSOME AND ALTERED EXPRESSION OF IFN-RESPONSE RELATED GENES ARE HALLMARKS OF MONOCYTES FROM LUPUS PATIENTS WITH RENAL DISEASE
Authors: A. M. Patiño-Trives, C. Perez-Sanchez, A. Ibañez-Costa, M. Luque-Tévar, M. D. C. Abalos-Aguilera, I. Arias de la Rosa, D. Ruiz, P. Seguí Azpilcueta, M. Espinosa, N. Barbarroja Puerto, J. P. Castaño, R. M. Luque Huertas, M. A. Aguirre, C. Lopez-Pedrera
Journal: Annals of the Rheumatic Diseases (2021)

Background: To date, novel mechanisms such as the involvement of splicing machinery components in lupus nephropathy and its interplay with the transcriptome in innate immune cells have not been evaluated. Objectives: 1- To identify altered transcriptomic signatures associated with the immune response of monocytes from SLE patients and its association with clinical features. 2- To evaluate the role of the spliceosome linked to the transcriptomic profile of SLE monocytes. 3- To analyze mechanistically the impact of anti-dsDNA antibodies (Ab) and the modulation of the spliceosome in the SLE monocytes activity. Methods: Sixty SLE patients and forty healthy donors (HD) were included in the study. Infiltration rate of myeloid cells and its association with clinical features were analyzed in kidney biopsies by Immunohistochemistry. In parallel, circulating monocytes were purified from peripheral blood by immune-magnetic selection. The expression of a set of 770 genes related to autoimmune/inflammatory diseases was evaluated using NanoString Technologies. The levels of the main 45 components of the splicing machinery were further analyzed in these samples using a microfluidic qPCR array (Fluidigm). An extensive clinical/serological evaluation was also performed, comprising disease activity, renal involvement parameters, autoAb profile, and the systemic inflammatory status (27-plex Assay). Finally, in vitro studies involving anti-dsDNA-IgG Ab treatment and over/down-expression of splicing machinery components were carried out to analyze their effects in the monocyte activity. Results: Infiltration of CD68 expressing cells was confirmed in kidney biopsies and associated with parameters of kidney failure (C3/C4, chronic index), highlighting the key role of the myeloid compartment in lupus nephropathy. Gene expression profiling recognized 156 genes differentially expressed in SLE monocytes compared with HDs, including 87 genes up-regulated and 69 down-regulated. Functional analysis showed that most dysregulated genes were associated with the IFN response (i.e. IFIT1, IFI44, IFI44L, RSAD2). In parallel, the altered expression of 27 spliceosome components was demonstrated in SLE monocytes compared with HD, including 3 up-regulated and 24 down-regulated. Correlation studies demonstrated that the aberrant expression of splicing machinery components was linked to the altered interferon signature and the plasma inflammatory profile. This aberrant profile at molecular level was associated with the disease activity status, anti-dsDNA positivity and C3/C4 levels. Interestingly, SLE patients with renal disease displayed a simultaneous alteration of both, the IFN and the spliceosome signatures in monocytes, along with an enlarged pro-inflammatory profile in plasma. Logistic regression models that integrated the concomitant alteration of some splicing machinery components and IFNs genes identified lupus nephritis patients with high accuracy. Mechanistic studies showed that in vitro treatment of monocytes from HDs with anti-dsDNA promoted a concomitant deregulation of the IFN signature and the expression of several spliceosome components (i.e. PTB, RBM17, RNU6ATAC). Finally, the over/down-expression of selected spliceosome components (PTB and RBM17) in monocytes from SLE patients reduced the active release of inflammatory cytokines and their adhesion capacity. Conclusion: 1) Monocytes from SLE patients with renal involvement exhibit a remarkable alteration of genes associated with the IFN response, further linked with the aberrant expression of several splicing machinery components. 2) Anti-dsDNA promoted the dysregulation in monocytes of both the IFN and spliceosome signatures, along with an active release of pro-inflammatory mediators. 3) The modulation of key splicing components in monocytes from SLE patients reduce their pro-inflammatory status and migration capacity. Ongoing studies may provide novel biomarkers and therapeutic tools to treat lupus nephropathy. Acknowledgements: Funded by ISCIII, PI18/00837 and RIER RD16/0012/0015 co-funded with FEDER Disclosure of Interests: None declared