Alopecia areata is an autoimmune disease characterised by hair loss, which occurs when T cells of the immune system mistakenly attack hair follicles. To restore control over hyperactive immune cells, researchers developed a cutting-edge approach to deliver T cell regulators directly to sites of hair loss and halt autoimmune activity. The findings, published in the journal Advanced Materials, demonstrate marked and lasting increase in hair regrowth in models of the disease.

The immune system evolved to safeguard against the overactivation that occurs when it mistakenly attacks our own tissues, as seen in autoimmune conditions. In conditions like Alopecia areata, the specialised cells known as regulatory T cells (Tregs) fall short in protecting hair follicles. Current immunosuppressants used in Alopecia areata target both T cells and regulatory T cells, failing to address the core issue and increasing the risk of disease recurrence once treatment stops. Moreover, systemic immune therapy suppresses the entire immune system, leaving patients vulnerable to infections and malignancies.

The approach tested in this study marks a departure from current therapeutic strategies, which typically utilise immunosuppressants to suppress the immune system. Rather than globally suppressing the immune system, the researchers aimed to locally restore well-controlled immune activity directly at sites of hair loss by increasing levels of regulatory T cells, whose numbers are reduced in Alopecia areata. This targeted approach was achieved with a microneedle patch, which delivers drugs across the tough outer layer of skin more effectively than topical creams and avoids stimulation of pain receptors, which are located deeper within the skin.

The patches were applied to murine models of Alopecia areata 10 times over a course of three weeks, with more than eight weeks of observation. Hair regrowth was observed as early as three weeks after the initiation of treatment. The researchers also tested microneedle patches loaded with baricitinib, a drug approved for severe Alopecia areata, but found that regulatory T cells recruitment was inferior to that associated with the IL-2/CCL22 patch. The researchers are exploring the possibility of applying their approach to other immune-mediated skin diseases, such as vitiligo and psoriasis. The therapy is not ready for clinical use yet.