Tear miRNAs identified in a murine model of Sjögren's Syndrome as potential diagnostic biomarkers and indicators of disease mechanism

Abstract

ObjectiveThe tear miRNAome of the male NOD mouse, a model of ocular symptoms of Sjogrens syndrome (SS), was analyzed to identify possible tear biomarkers of the disease. MethodsMale NOD mice, aged 12-14 weeks, were used to identify tear miRNAs associated with development of autoimmune dacryoadenitis. Age-matched female NOD mice that do not develop the autoimmune dacryoadenitis characteristic of SS were used as negative controls while age- and sex-matched male BALB/c mice served as healthy controls. Total RNA was isolated from stimulated tears pooled from 5 mice per sample and tear miRNAs were sequenced and analyzed. Putative miRNA hits were validated using RT-qPCR in a separate mouse cohort, and the pathways influenced by the validated hits were identified using Ingenuity Pathway Analysis. ResultsIn comparison to tears from both healthy (male BALB/c) and negative control (female NOD) mice, initial analysis identified 7 upregulated and 7 downregulated miRNAs in male NOD mouse tears. Of these, 8 were subsequently validated by RT-qPCR in tears from additional mouse cohorts. miRNAs previously implicated in SS pathology included mmu-miR-146a/b-5p, which were significantly downregulated in the male NOD mouse tears, as well as mmu-miR-150-5p and mmu-miR-181a-5p, which were upregulated in the male NOD mouse tears. All other validated hits including the upregulated miR-181b-5p and mmu-miR-203-3p, as well as the downregulated mmu-miR-322-5p and mmu-miR-503-5p, represent novel putative indicators of autoimmune dacryoadenitis in SS. ConclusionsA panel of differentially expressed miRNAs were identified in tears of SS model male NOD mice, including some never previously linked to SS. These may have potential utility as diagnostic biomarkers for ocular symptoms of SS; evaluation of the pathways influenced by these dysregulated miRNAs may also provide further insights into SS pathogenesis.