N-glycosylation profiling of serum immunoglobulin in opisthorchiasis patients.

Alteration of immunoglobulin glycosylation correlates with inflammatory diseases and infectious diseases including parasitic infections. Immunoglobulin glycosylation patterns may be implicated in disease development and have also been proposed as diagnostic tools for several diseases. Previous studies have reported the immunoglobulin profiles in experimental animals and in patients infected with the carcinogenic human liver fluke, Opisthorchis viverrini. However, the N-glycosylation profiles of immunoglobulins and their subclass-specific glycoforms in opisthorchiasis patients have never been elucidated. Here, N-glycosylation patterns of immunoglobulins and their subclass-specific glycoforms in sera of O. viverrini-infected patients were investigated using triple quadrupole mass spectrometry coupled with multiple reaction monitoring. Peptide fragmentation was utilized to quantify the immunoglobulin glycoforms normalized to the unique peptide of each subclass. Overall, serum levels of IgG and IgA in O. viverrini patients were significantly increased compared to uninfected controls. Twenty-seven glycoforms were detected based on analysis of detached glycans in all immunoglobulin subclasses. The abundance of immunoglobulin glycopeptides in serum of opisthorchiasis patients deviated significantly from controls. Immunoglobulin glycosylation patterns were associated with both pro- and anti-inflammatory properties. In conclusion, O. viverrini infection alters the serum immunoglobulin glycosylation profile and these changes could distinguish between O. viverrini-infected individuals and healthy controls. SIGNIFICANCE: We demonstrated that both quantities and glycoforms of serum immunoglobulin subclasses were altered in Opisthorchis viverrini-infected individuals as investigated by the QqQ-MS-MRM method. Patterns of immunoglobulin with a specific glycoform might contribute to immune responses to O. viverrini infection.