Glycomic Analysis of Tear and Saliva in Ocular Rosacea Patients: The Search for a Biomarker

Abstract

The purpose of this study was to study changes in glycosylation in tear and saliva obtained from control and ocular rosacea patients in order to identify potential biomarkers for rosacea. Tear fluid was collected from 51 subjects (28 healthy controls and 23 patients with ocular rosacea). Saliva was collected from 42 of the same subjects (25 controls and 17 patients). Pooled and individual samples were examined to determine overall glycan profiles and individual variations in glycosylation. O-and N- glycans were released from both patients and control subjects. Released glycans were purified and enriched by solid-phase extraction (SPE) with graphitized carbon. Glycans were eluted based on glycan size and polarity. SPE fractions were then analyzed by high-resolution mass spectrometry. Glycan compositions were assigned by accurate masses. Their structures were further elucidated by tandem mass spectrometric using collision-induced dissociation (CID), and specific linkage information was obtained by exoglycosidase digestion. N- and O-glycans were released from 20-μL samples without protein identification, separation, and purification. Approximately 50 N-glycans and 70 O-glycans were globally profiled by mass spectrometry. Most N-glycans were highly fucosylated, while O-glycans were sulfated. Normal tear fluid and saliva contain highly fucosylated glycans. The numbers of sulfated glycans were dramatically increased in tear and saliva of rosacea patients compared to controls. Glycans found in tear and saliva from roseatic patients present highly quantitative similarity. The abundance of highly fucosylated N-glycans in the control samples and sulfated O-glycans in ocular rosacea patient samples may lead to the discovery of an objective diagnostic marker for the disease.

Ocular rosacea: a review

“…We have previously shown a high abundance of O-linked oligosaccharides in the tears of patients with rosacea (52) . More recently, we published our results on glycomic analysis of tears and saliva, and previous results were confirmed in both fluids with N-glycans dramatically decreased in roseatic tear and saliva samples (53) . Furthermore, we described highly novel glycans that may be potential biomarkers for rosacea (53) .…”

Post-translational modifications and their applications in eye research

“…In total, ~50 N-glycans and 70 O-glycans were profiled, and fucosylated N-glycans were revealed to be significantly underexpressed while sulfated O-glycans was over-expressed. These factors made them potential markers to consider for this particular ocular status (153). Detailed profiling of proline-rich protein 4, a potential biomarker of lacrimal gland acinar cell function (154), in normal human tears was conducted by applying one-and two-dimensional MS analysis.…”

Ocular Rosacea—a Review

“…43,44 A high index of suspicion in patients with recurrent belpharoconjunctivitis, hordeola, chalazia, corneal infiltrates, thinning, or perforation without history of trauma or other definitive cause is hence crucial to correctly diagnose this condition, especially in cases without dermatological involvement. Symptomatic management without treatment of the underlying pathology may often be associated with an inadequate response.…”