Peripheral Blood DNA Methylation Changes Precede Lymphoma Diagnosis in Primary Sjögren's Disease.

OBJECTIVE

Primary Sjögren's disease (SjD) is a systemic autoimmune disease associated with an increased risk of lymphoma. The molecular mechanisms underlying lymphomagenesis remain poorly understood, and sensitive biomarkers for early identification of patients at high risk of developing lymphoma are lacking. This study investigated whether DNA methylation patterns in blood are associated with subsequent development of lymphoma in patients with SjD.

METHODS

Peripheral blood DNA samples collected from patients with SjD between 1998 and 2013 were analyzed using the Illumina HumanMethylation450K BeadChip. There were 6 patients who developed lymphoma at one or more years after blood sampling, henceforth referred to as "patients with SjD pre-lymphoma"; 84 patients with SjD did not develop lymphoma, and they are henceforth referred to as "patients with only SjD." Epigenome-wide association analyses were adjusted for age, sex, and estimated blood cell-type proportions. Differentially methylated CpG positions (DMPs) were defined by Bonferroni-corrected P ≤ 1.3 × 10-7 and |Δβ| > 0.05. Functional enrichment was assessed using Enrichr and Interferome version 2.01.

RESULTS

A total of 473 autosomal and 1 X-chromosomal DMPs distinguished patients with SjD pre-lymphoma from patients with only SjD, with 87% of DMPs being hypomethylated in patients with SjDpl. The most significant DMP mapped to Thymidine kinase 1 (TK1; P = 7.6 × 10-15, Δβ = -0.16), followed by FCER1G and MDH2. Functional annotation revealed enrichment for immune activation, leukocyte signaling, and vesicle-mediated secretion pathways. Patients with SjD pre-lymphoma also exhibited reduced natural killer cells and increased monocyte proportions, consistent with an altered immune milieu.

CONCLUSION

Distinct DNA methylation changes precede lymphoma in SjD, affecting genes involved in immune regulation, cytotoxic function, and proliferation. Although exploratory and requiring replication, these findings provide a framework for integrating epigenetic, clinical, and serologic markers to inform early risk stratification in patients with SjD.