AB0749 IDENTIFICATION OF POTENTIAL EPIGENETIC BIOMARKERS FOR THE DIAGNOSIS AND PROGNOSIS OF RHEUMATOID ARTHRITIS
Authors: A. Mucientes, G. M. Martín-Núñez, J. M. Lisbona-Montañez, P. Ruiz-Limon, R. Redondo-Rodriguez, S. Manrique-Arija, I. Ureña, L. Cano-Garcia, I. Moreno-Indias, N. Mena-Vázquez, A. Fernández-Nebro
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Epigenetic modifications can act as biomarkers and are the result of the interaction between genetic and environmental factors. These DNA alterations have been linked to rheumatoid arthritis (RA). <h3>Objectives:</h3> Identify new potential epigenetic biomarkers for diagnosis and prognosis in RA patients. <h3>Methods:</h3> Cross-sectional prospective cohort study, in which 32 patients (16 severe RA, 16 non-severe RA) and 32 healthy controls (discovery cohort) were studied. The severity phenotype was defined by cumulative Socre disease activity (DAS28-ESR) ≥3.2, positive rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA), as well as higher counts of Collinsela aerofaciens (OTU ≥ 0.15). (1,2). Global DNA methylation is processed using Infinium Mmethylation EPIC BeadChip (Illumina, San Diego, CA, USA). Validation of the HM850k array results for selected CpGs was performed by pyrosequencing (PyroMark Q48) in both the discovery cohort and the rest of the initial cohort (validation cohort: 78 patients and 78 controls). Pyrosequencing included information on the CpGs adjacent to the CpGs of the array (nomenclature: number of nucleotides with respect to the position of the CpGs of the arrays-Down-code CpG array). A descriptive analysis and bivariate analysis were performed for statistical comparison between the different groups of subjects, in addition an analysis of the area under the ROC curve (AUC) was carried out to identify the diagnostic potential of the validated CpGs. <h3>Results:</h3> More than half of the subjects were women (≥75%), with a mean age of 56 years. No significant differences were found in most epidemiological characteristics and comorbidities between the compared groups of both cohorts. However, in the patient group there were more smokers (62% vs. 40%; p=0.015 and 44% vs. 29%, p=0.036). Among patients, subjects with severe RA compared to non-severe subjects had a higher average DAS28-ESR (3.6 ± 0.6 vs. 2.9 ± 0.7 mg/l, p = 0.017 and 3. 6 ±0.9 vs. 2.5 ±0.8 mg/l, p&lt;0.001), and elevated ACPA (68% vs. 31%, p=0.034 and 57% vs. 22%c, p=0.004) in both cohorts. Patients with severe RA had a higher frequency of erosions (81% vs. 37%, p=0.012), and treatment with biological therapy (56% vs. 12%, p=0.009), as well as a higher abundance of Collinsela (median [IQR], 0.3 [0.1-1.7] vs. 0.1 [0.0-0.4] mg/l, p=0.003) in the discovery cohort. Regarding the methylation analysis, of all the differentially methylated CpGs in the HM850k matrix, those CpGs annotated in genes or pseudogenes, with minimal change in the β-value ≥ 0.10 between groups, p value ≤0.01, and that were in differentially methylated regions (p&lt;0.05) for validation by pyrosequencing. Differential changes in methylation levels between the compared groups were identified for the CpGs described in Table 1. These CpGs presented a potential diagnosis according to the AUC ROC (Table 2). <h3>Conclusion:</h3> The level of DNA methylation at selected CpG sites is different in RA and depending on the severity of the disease. These CpGs could act as potential biomarkers in the diagnosis of RA. <h3>REFERENCES:</h3> 1. Ruiz-Limón P, Mena-Vázquez N, Moreno-Indias I, Manrique-Arija S, Lisbona-Montañez JM, Cano-García L, et al. Collinsella is associated with cumulative inflammatory burden in an established rheumatoid arthritis cohort. Biomed Pharmacother. 2022 Sep;153:113518. 2. Mena-Vázquez N, Rojas-Gimenez M, Fuego-Varela C, García-Studer A, Perez-Gómez N, Romero-Barco CM, et al. Safety and Effectiveness of Abatacept in a Prospective Cohort of Patients with Rheumatoid Arthritis-Associated Interstitial Lung Disease. Biomedicines. 2022 Jun;10(7). <h3>Acknowledgements:</h3> FIS Grant PI18/00824 (Instituto Carlos III, Fondos FEDER). "Ayuda de Garantía Juvenil 2020" of the University of Malaga, Spain (SNGJ5Y6-12). Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) (RD21/0002/0037). <h3>Disclosure of Interests:</h3> <b>None declared.</b>