Serum galectin-9 levels in some inflammatory skin diseases: a pilot study

Background Galectin-9 (Gal-9) is a tandem-repeat galectin family member. It is a physiological ligand for T-cell immunoglobulin and mucin-domain containing molecule-3. The interaction of T-cell immunoglobulin and mucin-domain containing molecule-3 and Gal-9 induces apoptosis in T helper 1 cells and T helper 17 cells. Atopic dermatitis (AD), psoriasis, and allergic contact dermatitis (ACD) are common, chronic, and relapsing inflammatory skin diseases associated with various immunologic abnormalities. Objective To investigate a potential role of Gal-9 in the pathogenesis of AD, psoriasis, and ACD and to assess its relation to the disease severity. Patients and methods Fifty-four patients (18 AD, 18 psoriasis, and 18 ACD) with different grades of severity and 18 healthy participants were included in the study. The severity of the diseases was determined by scoring of atopic dermatitis in AD cases, by psoriasis area and severity index score in psoriasis cases, and by staging of ACD. Serum Gal-9 levels were measured in all patients and controls by enzyme-linked immunosorbent assay. Results A statistically significant elevation in serum levels of Gal-9 in patients with AD was detected and was positively correlated with the disease severity. No statistical significant differences were detected between the serum levels of Gal-9 in psoriasis and ACD groups and control group. Limitations The small sample size and the inability to study Gal-9 in the skin were the main limitations. Conclusion It could be concluded that Gal-9 may be implicated in the pathogenesis of AD and is correlated with the disease severity. Its role in psoriasis and ACD could not be verified by this study. Restoration of immune equilibrium lost in AD, psoriasis, and ACD by galectins requires more and more recognition of these immunoregulatory molecules, which might be considered as a new therapeutic tool