Mutant HSP70 reverses autoimmune depigmentation in vitiligo

Area of Science:

• Immunology
• Dermatology
• Molecular Biology

Background:

• Vitiligo is an autoimmune disease causing melanocyte destruction and depigmentation, affecting 0.5% of the population.
• Current vitiligo treatments have limited effectiveness.
• Inducible heat shock protein 70 (HSP70i) links stress to immune responses and is implicated in vitiligo pathogenesis.

Purpose of the Study:

• To investigate the role of HSP70i in T cell-mediated vitiligo.
• To evaluate a modified HSP70i (HSP70iQ435A) as a potential therapeutic for vitiligo.

Main Methods:

• Observed dendritic cell (DC) phenotype in vitiligo patients and mouse models.
• Utilized DNA vaccination with melanocyte antigens and HSP70i constructs in mouse models.
• Performed mutational analysis of HSP70i to identify key domains for DC activation.
• Assessed the therapeutic efficacy of HSP70iQ435A in preventing and reversing depigmentation in mouse models.
• Ex vivo treated human skin explants to evaluate T cell phenotype modulation.

Main Results:

• HSP70i induces an inflammatory DC phenotype, observed in both vitiligo patients and mouse models.
• A specific peptide (QPGVLIQVYEG) within HSP70i is crucial for DC activation; mutant HSP70i (HSP70iQ435A) failed to induce depigmentation.
• HSP70iQ435A bound human DCs, reduced their activation, and shifted DCs towards a tolerogenic phenotype in mice.
• HSP70iQ435A DNA prevented spontaneous vitiligo in mice and led to 76% pigmentation recovery in a rapid depigmentation model.
• Treatment with HSP70iQ435A prevented T cell infiltration into mouse skin and shifted human T cells from effector to quiescent phenotypes.

Conclusions:

• Modified HSP70i, specifically HSP70iQ435A, can prevent and reverse vitiligo.
• HSP70iQ435A demonstrates therapeutic potential by modulating DC and T cell responses, offering a promising new avenue for vitiligo treatment.