Differential Expression of Galectin-1 and Galectin-9 in Immune-Mediated Inflammatory Diseases.

Galectin-1 and -9 (Gal1/9) are essential mediators of immune-inflammatory responses, which makes these proteins potential biomarkers for immune-mediated diseases (IMIDs), such as rheumatoid arthritis (RA), psoriasis (PS), psoriatic arthritis (PsA), inflammatory bowel disease, and systemic lupus erythematosus (SLE). Our aim was to evaluate plasma Gal1/9 differences between IMID patients and healthy donors (HD). We analyzed 980 plasma samples divided into two analytical cohorts (600 discovery group and 380 validation group). Generalized linear models estimated Gal1/9 levels, adjusting for sex, age, storage time, and plate variability. In the overall IMID group, plasma Gal1 levels were comparable to those of HD, while Gal9 levels were significantly elevated. Levels varied across individual diseases: SLE patients consistently showed the highest Gal1/9 levels compared to both HD and other IMIDs, and RA patients had elevated Gal9 levels versus HD. Both Gal1 and Gal9 plasma levels correlated positively with higher disease activity, and Gal1 was higher in patients with longer disease duration. After adjustment for these confounders, SLE and RA patients maintained the highest Gal9 levels compared to HD. Our study demonstrates that Gal1 and Gal9 are differentially expressed across IMIDs, with particularly elevated levels in SLE, and both galectins are associated with disease activity.