Thyroid-associated ophthalmopathy (TAO) is the most prevalent orbital disease in adults caused by an autoimmune disorder, which can lead to disfigurement and vision impairment. Developing effective treatments for this condition presents challenges due to our limited understanding of its underlying immune aberrations. In this study, we profiled the immune components in the peripheral blood of patients with TAO as well as healthy individuals, utilizing single-cell RNA sequencing and B-cell receptor repertoires (BCR) analysis. We observed a significant reduction in the proportions of regulatory B cells (Bregs) and type 2 conventional dendritic cells (DCs) in patients with TAO during the active phase. Conversely, there was a significant increase in the proportion of type 1 DCs. Further analysis of cell differentiation trajectory revealed potential impairment in the transition of B cells towards Breg phenotype during the active phase of TAO. Besides, the activation process of TAO appeared to involve inflammation and immune dysfunction, as indicated by the dynamic changes in the activities of key regulators. The abnormalities in the peripheral immune system, such as the reduced capacity of Bregs to suppress inflammation, were primarily driven by the enhanced interaction among Breg, DCs, and monocytes (i.e., CD22-PTPRC and BTLA-TNFRSF14). Collectively, our findings offer a comprehensive insight into the molecular regulation and cellular reconfiguration during the active phase of TAO at the single-cell level, in order to explore the pathogenesis of TAO and provide new ideas for the future treatment of TAO.

Background: Thyroid‐associated ophthalmopathy (TAO) is the most common orbital disease in adults, potentially leading to disfigurement and visual impairment. However, the causes of TAO are not fully understood. IL‐35⁺B cells are a newly identified regulatory B cells (Bregs) in maintaining immune balance in various autoimmune diseases. Yet, the influence of IL‐35⁺Bregs in TAO remains unexplored.Methods: This study enrolled 36 healthy individuals and 14 TAO patients. We isolated peripheral blood mononuclear cells and stimulated them with IL‐35 and CpG for 48 h. Flow cytometry was used to measure the percentages of IL‐35⁺Bregs.Results: The percentage of circulating IL‐35⁺Bregs was higher in TAO patients, and this increase correlated positively with disease activity. IL‐35 significantly increased the generation of IL‐35⁺Bregs in healthy individuals. However, B cells from TAO patients exhibited potential impairment in transitioning into IL‐35⁺Breg phenotype under IL‐35 stimulation.Conclusions: Our results suggest a potential role of IL‐35⁺Bregs in the development of TAO, opening new avenues for understanding disease mechanisms and developing therapeutic approaches.

Introduction Involved site radiation therapy (ISRT) is a widely used treatment for primary ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma with control rates over 85%; however, its complications could reach 30%–50%. Intralesional rituximab injection has shown promising results with remission rates between 65% and 100% and minimal complications. This study aimed to conduct a multicentre randomised controlled clinical trial to compare the safety and efficacy of intralesional rituximab injection versus ISRT on primary ocular adnexal MALT lymphoma. Methods and analysis This is a multicentre randomised controlled trial and will be conducted at eight ophthalmic departments and institutes in China. 108 patients with primary ocular adnexal MALT lymphoma will be enrolled and randomised to undergo intralesional rituximab injection or ISRT. Comprehensive examinations will be performed before and after the treatment. The primary outcome is the cumulative occurrence rate of complications of grade ≥2 within 5 years after treatment commencement. The main secondary outcome is overall response rate, and progression-free survival, time to next treatment and overall survival will also be compared between the groups. Ethics and dissemination Ethical approval has been obtained from the Ethics Committee of the Zhongshan Ophthalmic Center (ID: 2023KYPJ125-3; V.20240818) and the ‘5010 Plan’ evaluation committee at Sun Yat-sen University, Guangzhou, China, and all subcentres. All the participants will be required to provide written informed consent. The results will be disseminated through scientific meetings and published in peer-reviewed journals. Trial registration number NCT06190301.