醣晶片於疾病之應用與發展

Abstract

Abstract Carbohydrates play an important role in health and disease. Infectious diseases, inflammation, and cancer are disorders that have been linked to glycosylation phenotypes. To understand, diagnose, and predict the progression of such carbohydrate-mediated diseases, glycan array is a promising new tool for investigating the complicated interactions of carbohydrates with carbohydrate-binding proteins. The glycan array platform covalently immobilizes carbohydrate structures to a solid surface, mimicking the multivalent display of glycan structures at the cell surface, and allowing sensitive and high-throughput characterization of carbohydrate-binding proteins. In studying influenza virus infection, the glycan array was used to quantitatively analyze the influenza virus surface glycoprotein, heamagglutinin (HA). To elucidate the role of HA glycosylation in this important interaction, various defined HA glycoforms were prepared and their binding affinity and specificity were studied using a synthetic sialosides (SA) microarray. Truncation of the N-glycan structures on HA increased SA binding affinities, while decreasing specificity toward disparate SA ligands. HA protein bearing only a single N-linked GlcNAc at each glycosylation site showed better binding affinity toward sialosides. Antibodies elicited by monoglycosylated HA showed higher neutralization activity against various influenza viruses subtypes than the fully glycosylated HAs. Thus, removal of structurally nonessential glycans on viral surface glycoproteins may be an effective and general approach for vaccine design against influenza and other human viruses. With respect to biomarkers, the glycan array was used to probe the circulating antibodies in breast cancer versus healthy individuals to the cancer-related carbohydrate antigen, Globo H. Aberrant glycan structures arose in cancer and can be a potential biomarker for the early detection and treatment of cancer. This work established that the glycan array can be used to monitor differences in the carbohydrate-binding capacity of serum antibodies from individuals who are healthy versus those with breast cancer. This was demonstrated by binding of sera antibodies to the carbohydrate antigen, Globo H, which is highly expressed on breast cancer cells. Antibodies against Globo H from breast cancer patients were significantly higher than normal donors and increaseed as the disease progressed. This represents a powerful tool that can be developed for blood-based high throughput cancer diagnostics. When comparing the sensitivity between glycan array and the tranditional ELISA method, it was found that the array method required only much less material (atto-mole amounts) and is 6 to 8 orders of magnitude more sensitive.