Analysis of haptoglobin N-glycome alterations in inflammatory and malignant lung diseases by capillary electrophoresis

A CE-based method was introduced to compare the N-glycosylation profile of haptoglobin in normal and pathologic conditions. To assess the biomarker potential of glycosylation changes in various lung diseases, haptoglobin was isolated from plasma samples of healthy, pneumonia, chronic obstructive pulmonary disease, and lung cancer patients by means of two haptoglobin-specific monoclonal antibodies. Haptoglobin N-glycans were then enzymatically released, fluorescently labeled, and profiled by CE. Disease-associated changes of core and antennary fucosylation were identified by targeted exoglycosidase digestions and their levels were compared in the different patient groups. Terms such as core- and arm-fucosylation degree, as well as branching degree, were introduced for easier characterization of the changes and statistical analysis was used to examine which structures were responsible for the observed differences. Increased level of 1-6 fucosylated tri-antennary glycans was found in all disease groups compared to the control. Elevated amounts of core- and arm-fucosylation on tetra-antennary glycans were detected in the lung cancer group compared to the chronic obstructive pulmonary disease group. A larger scale study is necessary to confirm and validate these preliminary findings in the glycosylation changes of haptoglobin, so could then be used as biomarkers in the diagnosis of malignant and inflammatory lung diseases.