Mucin O-glycans as regulators of pathogen virulence: glycan synthesis, mechanistic investigation, and therapeutic potential

Current estimates suggest that nearly 1.3 million lives are lost annually to antibiotic-resistant infections, with this number rising to 10 million by 2050. Antibiotic resistance results in failed treatment, prolonged hospital stays, and increases the financial burden placed on medical systems and society. Therefore, novel approaches to antibiotic use are urgently needed.

Recently, a novel class of anti-virulence compounds based on mucosal glycans were discovered, which are active against a range of pathogenic cross-kingdom species, including fungal, Gram-positive, and Gram-negative bacterial pathogens. These mucin O-glycans do not directly affect pathogen survival but instead repress virulence, thereby increasing susceptibility to host immune pathways and indirectly reducing infection load. By exerting their activity through virulence attenuation instead of broad-spectrum elimination, these compounds can promote the reestablishment of a healthy microbiome and are expected to be at a reduced risk of developing drug resistance. Although this exciting new class of compounds has demonstrated broad activity, the mechanism(s) by which these glycans act has not yet been elucidated. By identifying their discrete molecular target(s), specific binding interactions can be analyzed and more drug-like glycomimetic therapies can be developed.

Mucins contain hundreds of different O-glycans which are not commercially available, cannot be purified as single structures from native sources, and are not readily amenable to solid-phase synthesis. Therefore, in ongoing work we have been developing a platform to generate individual mucin glycan structures and evaluate their ability to regulate pathogen virulence. In the further development and application of this platform, specific aims of the current proposal are focused on: (i) the recombinant expression of predicted virulence-regulating proteins; (ii) the investigation of mucin glycan binding to virulence-regulating proteins through parallel techniques; and (iii) further expansion of the mucin glycan library and the development of next-generation glycomimetic molecules.

The proposed project will improve our understanding of mucus–pathogen relationships, provide insights into virulence-attenuating mechanism(s), and provide the next steps to development of an innovative therapeutic.