Notch1 hyperactivity drives ubiquitination of NOX2 and dysfunction of CD8+ regulatory T cells in patients with systemic lupus erythematosus

Zixin Yuan; Mengdi Liu; Lei Zhang; Li Jia; Siao Hao; Danhua Su; Longhai Tang; Chunhong Wang; Mingyuan Wang; Zhenke Wen

doi:10.1093/rheumatology/keae231

Notch1 hyperactivity drives ubiquitination of NOX2 and dysfunction of CD8+ regulatory T cells in patients with systemic lupus erythematosus

Rheumatology (Oxford). 2024 Apr 23:keae231. doi: 10.1093/rheumatology/keae231. Online ahead of print.

Authors

Zixin Yuan^{1

2}, Mengdi Liu^{1

2}, Lei Zhang^{1

2}, Li Jia^{1

2}, Siao Hao^{1

2}, Danhua Su^{1

2}, Longhai Tang³, Chunhong Wang⁴, Mingyuan Wang³, Zhenke Wen^{1

2}

Affiliations

¹ Jiangsu Key Laboratory of Infection and Immunity, The Fourth Affiliated Hospital of Soochow University, Institutes of Biology and Medical Sciences, Suzhou Medical College of Soochow University, Soochow University, Suzhou, China.
² MOE Key Laboratory of Geriatric Diseases and Immunology, Suzhou Medical College of Soochow University, Soochow University, Suzhou, China.
³ Division of Research Center, Suzhou Blood Center, Suzhou, China.
⁴ Cyrus Tang Hematology Center, State Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou, China.

PMID: 38652598
DOI: 10.1093/rheumatology/keae231

Abstract

Objectives: Patients with systemic lupus erythematosus (SLE) display heightened immune activation and elevated IgG autoantibody levels, indicating compromised regulatory T cell (Tregs) function. Our recent findings pinpoint CD8+ Tregs as crucial regulators within secondary lymphoid organs, operating in a NOX2-dependent mechanism. However, the specific involvement of CD8+ Tregs in SLE pathogenesis and the mechanisms underlying their role remain uncertain.

Methods: SLE and healthy individuals were enlisted to assess the quantity and efficacy of Tregs. CD8+CD45RA+CCR7+ Tregs were generated ex vivo, and their suppressive capability was gauged by measuring pZAP70 levels in targeted T cells. Notch1 activity was evaluated by examining activated Notch1 and HES1, with manipulation of Notch1 accomplished with Notch inhibitor DAPT, Notch1 shRNA, and Notch1-ICD. To create humanized SLE chimeras, immune-deficient NSG mice were engrafted with PBMCs from SLE patients.

Results: We observed a reduced frequency and impaired functionality of CD8+ Tregs in SLE patients. There was a downregulation of NOX2 in CD8+ Tregs from SLE patients, leading to a dysfunction. Mechanistically, the reduction of NOX2 in SLE CD8+ Tregs occurred at a post-translational level rather than at the transcriptional level. SLE CD8+ Tregs exhibited heightened Notch1 activity, resulting in increased expression of STUB1, an E3 ubiquitin ligase that binds to NOX2 and facilitates its ubiquitination. Consequently, restoring NOX2 levels and inhibiting Notch1 activity could alleviate the severity of the disease in humanized SLE chimeras.

Conclusion: Notch1 is the cell-intrinsic mechanism underlying NOX2 deficiency and CD8+ Treg dysfunction, serving as a therapeutic target for clinical management of SLE.

Keywords: CD8+ regulatory T cells; NOX2; Notch1; STUB1; Systemic lupus erythematosus.