Ubiquitin-specific protease 34 in macrophages limits CD8 T cell-mediated onset of vitiligo in mice.

As an autoimmune disorder, vitiligo is characterized by depigmented skin macules. CD8T cells and macrophages enrichment promote the onset of vitiligo, while the role of macrophages to CD8T is not well deciphered. To develop a mouse model of vitiligo with prominent epidermal depigmentation, Krt14-Kitl* transgenic mice containing an elevated number of melanocytes in the epidermis with membrane-bound Kit ligand (Kitl*) were adoptively transferred with premelanosome protein (PMEL) CD8 T cells. On the other hand, Krt14-Kitl* mice were mated with ubiquitin-specific protease 34 (USP34) mice to decipher the role of USP34 in vitiligo. Vitiligo scores and PMEL CD8 T cell enrichment were detected with flow cytometry. Human peripheral blood mononuclear cells (PBMCs) or mice bone marrow-derived macrophages (BMDMs) were incubated with lipopolysaccharide (LPS), CpG, or co-incubated with KU-55933, an ataxia telangiectasia-mutated (ATM) inhibitor. Chemokine (C-C motif) ligand 2 (CCL2), Ccl5, and interleukin (Il)-12α expression was assayed with real-time PCR, and p-IKKα/β was assayed with Western blots. USP34 was up-regulated in the PBMCs of vitiligo patients and LPS-stimulated BMDMs. USP34 deficiency did not affect the differentiation of CD11bF4/80 macrophages in the bone marrow. Immunoprecipitation demonstrated the interaction between USP34 and ATM. USP34 deficiency or KU-55933 administration promoted the induction of Ccl2, Ccl5, Il12α, and p-IKKα/β in LPS or CpG stimulated BMDMs; KU-55933 administration could not affect the expression of the above molecules in USP34 deficient BMDMs. It further revealed that USP34 deficiency promoted the development of vitiligo with increased PMEL CD8 T cell enrichment, which was not affected by KU-55933 administration. USP34 deficiency in macrophages promotes the onset of vitiligo with increased PMEL CD8 T cell enrichment, and USP34/ATM complex can be considered as a therapy target.