# Humoral immune responses to hyaluronan oligosaccharides in patients undergoing prosthetic valve surgery

## TL;DR

This study explores immune responses to hyaluronan fragments in patients with heart valve implants, finding that specific antibody patterns may be linked to post-surgery inflammation and valve deterioration.

## Contribution

The study identifies HA34 as a conserved immunodominant target and extends immune response understanding from xenogeneic to matrix-derived glycans in valve disease.

## Key findings

- All subjects had baseline anti-HA IgG and IgM antibodies, with HA2 showing the highest reactivity in ELISA.
- PGA identified HA34 as the dominant immunogenic fragment across all groups and time points.
- Anti-HA antibodies increased temporarily after surgery, peaking at one month and declining within 6–12 months.

## Abstract

Bioprosthetic heart valves (BHVs) are widely used in cardiac surgery but are limited by structural valve deterioration (SVD). The Translink study showed that immune responses to xenogeneic glycans contribute to SVD. Hyaluronan (HA), a glycosaminoglycan with size-dependent biological functions, has been implicated in inflammation, xenoreactivity, and valve calcification. This study investigated humoral immune responses to HA oligosaccharides in a subgroup of the Translink cohort.

Serum samples from 258 BHV recipients and 78 cardiac surgery controls were analyzed by ELISA, and a representative subset was further profiled using a printed glycan array (PGA). BHV recipients were classified with clinically significant SVD (A), as de novo implantation (B1), or long-term without SVD (B2). Controls included mechanical valve replacement or coronary artery bypass patients, either de novo (B1C) or long-term post-surgery (B2C). ELISA quantified IgG and IgM antibodies against HA fragments of increasing length (HA2, HA24, HA84), while PGA mapped fine specificity across HA2–HA40.

All subjects exhibited measurable baseline anti-HA IgG and IgM antibodies. ELISA revealed a fragment-length dependence, with the shortest fragment, HA2, showing the highest antibody binding, and progressively lower reactivity with longer oligomers. Following de novo cardiac surgery, both BHV recipients and controls showed a transient increase in anti-HA antibodies, peaking at one month and declining within 6–12 months. In contrast, PGA consistently identified HA34 as the dominant immunogenic fragment across all cohorts and time points.

Anti-HA antibodies are constitutively present in humans, undergo transient amplification after cardiac surgery, regardless of prosthesis type, and display marked fragment-length specificity. Short HA2 fragments predominate in ELISA responses, whereas intermediate-length oligomers, such as HA34, emerge as conserved, immunodominant targets in PGA. These findings extend the Translink paradigm from xenogeneic to matrix-derived glycan immunity and identify anti-HA antibodies as potential biomarkers of postoperative inflammation and tissue remodeling, which could be relevant to SVD.