2-Bromo-1,4-naphthoquinone Promotes CD8+ T Cell Expansion and Limits Th1/Th17 Cell Development to Alleviate Experimental Autoimmune Encephalomyelitis

Introduction

Multiple Sclerosis (MS) is a chronic autoimmune disease that primarily affects the Central Nervous System (CNS), impacting approximately 3 million people worldwide. The onset of MS is associated with various genetic, acquired, and environmental risk factors. Its progression involves a cascade of events such as immune system activation, immune cell infiltration across the blood-brain barrier into the CNS, demyelination, glial reaction, and axonal degeneration, eventually leading to disrupted neural signal transmission and neurological dysfunction. Current clinical interventions for MS mainly target the early peripheral immune processes of MS, but they cannot completely halt disease progression and may cause severe side effects. Therefore, there is an urgent need to develop new, safe, and effective drugs for MS treatment.

Naphthoquinones are widely present in various traditional Chinese herbs and have immune-regulating functions. Its derivative, 2-bromo-1,4-naphthoquinone (Bromo-1,4-naphthoquinone, BRQ), has shown good efficacy in an experimental autoimmune encephalomyelitis (EAE) mouse model. This study aims to explore the protective effects and potential mechanisms of BRQ in EAE, providing new therapeutic targets for MS.

Research Methods

This study utilized an EAE model induced in immunized C57BL/6 mice. BRQ was administered orally at different doses, and the clinical symptom scores, CNS inflammatory cell infiltration, and demyelination of the mice were observed and evaluated. Additionally, in vivo and in vitro experiments, such as oligodendrocyte precursor cell (OPC) differentiation experiments and cuprizone-induced demyelination mouse models, were conducted to assess the direct effects of BRQ on remyelination.

Bulk RNA sequencing (Bulk RNA-seq) was used to analyze the gene expression profiles of different immune cells in the peripheral immune tissues of EAE mice. Flow cytometry was used for validation to explore potential mechanisms and target cells of BRQ action. Further, CD8+ T cell depletion experiments were conducted to confirm whether the therapeutic effect of BRQ depends on CD8+ T cells.

Research Results

1. Oral administration of BRQ significantly reduced the clinical scores, CNS inflammatory cell infiltration, and degree of demyelination in EAE mice, showing both preventive and therapeutic effects.

2. BRQ did not directly promote OPC to OL differentiation and remyelination.

3. Bulk RNA-seq and cellular communication network analysis revealed that BRQ mainly acts on CD8+ T cells in the peripheral immune system, promoting their expansion and interaction with other immune cells.

4. CD8+ T cell depletion experiments confirmed that the therapeutic effect of BRQ in alleviating EAE symptoms depends on CD8+ T cells.

5. The expanded CD8+ T cells selectively inhibited antigen-specific CD4+ T cells, thereby suppressing the development of Th1 and Th17 cells, which alleviates EAE symptoms.

6. BRQ did not show obvious immunotoxicity in vivo, supporting its safety for further research and potential clinical application.

Research Significance

This study is the first to discover that BRQ can specifically promote CD8+ T cell expansion. These CD8+ T cells can inhibit the development of Th1/Th17 cells, thereby alleviating EAE/MS symptoms, revealing a unique mechanism of BRQ in treating MS. BRQ is expected to become a new drug candidate for treating MS and other autoimmune diseases.

The results of this study highlight the critical role of BRQ in regulating the pathogenesis of MS, providing a basis for its development as a novel therapeutic drug for MS.