Activated Leukocyte Cell Adhesion Molecule Modulates Th2 Immune Response in Atopic Dermatitis

Area of Science:

• Immunology
• Dermatology
• Molecular Biology

Background:

• Activated leukocyte cell adhesion molecule (ALCAM) is an immunoglobulin superfamily member highly expressed on dendritic cells.
• ALCAM and its receptor CD6 are crucial co-stimulatory molecules for T cell activation within the immunological synapse.
• Atopic dermatitis (AD) is a T helper 2 (Th2)-mediated allergic condition, but ALCAM's specific role in its pathogenesis remains largely unknown.

Purpose of the Study:

• To investigate the role of ALCAM in the pathogenesis of atopic dermatitis.
• To determine if ALCAM levels are altered in AD patients and correlate with disease severity.
• To elucidate the impact of ALCAM deficiency on Th2 immune responses and skin barrier function in AD models.

Main Methods:

• Serum ALCAM levels were quantified in pediatric AD patients and a murine model of AD induced by ovalbumin.
• Transepidermal water loss, clinical scores, Th2 immune responses, skin barrier gene expression, and T-cell activation were assessed in wild-type (WT) and ALCAM-deficient mice.
• An additional AD-like model was induced using oxazolone in WT and ALCAM-deficient mice for comparative analysis.

Main Results:

• Serum ALCAM levels were elevated in both pediatric AD patients and WT AD mice.
• ALCAM-deficient mice exhibited suppressed Th2-type cytokine production and reduced AD symptoms compared to WT mice.
• ALCAM deficiency led to decreased CD4+ effector T-cell counts, enhanced skin barrier gene expression, and an increased number of lamellar bodies.

Conclusions:

• ALCAM plays a significant role in atopic dermatitis pathogenesis.
• ALCAM contributes to AD by mediating Th2-dominant immune responses.
• ALCAM negatively impacts skin barrier function, exacerbating AD symptoms.