Objectives: This study aimed at establishing a mouse model of immune-related adverse in humanized BALB/c-hPD1/hCTLA4 mice to investigate their potential pathogenesis and explore therapeutic targets for immune-related arthritis and pneumonitis.Methods: Humanized BALB/c-hPD1/hCTLA4 mice were injected with vehicle or collagen-specific antibodies (CA) and immune checkpoint inhibitors (ICI, ipilimumab, anti-human CTLA-4; and nivolumab, anti-human PD-1), and some mice were treated with anti-TNF-α antibody, leading to the control, collagen antibody-induced arthritis (CAIA), CAIA+ICI and treatment groups. The severity of clinical arthritis and pneumonitis in mice was monitored longitudinally and the pathological changes in the joints and lungs were histologically analyzed and the contents of lung hydroxyproline were measured. The frequency of different subsets of T cells was analyzed by flow cytometry and multiplex immunofluorescency.Results: Compared with the control, the ICI group of mice developed the delayed onset of moderate degrees of arthritis while the CAIA+ICI group of mice exhibited the early onset of severe arthritis. Treatment with ICI caused severe pneumonitis, especially in the mice with CA. Flow cytometry analysis indicated a significantly higher frequency of splenic TNF-α⁺CD4⁺and TNF-α⁺CD8⁺T cells, but not other subsets of T cells tested, in the CAIA+ICI group of mice, relative to that in other groups of mice. Treatment with anti-TNF-α significantly mitigated the severity of arthritis and pneumonitis as well as deposition of collagen in lung of mice. The treatment also decreased the frequency of TNF-α⁺CD4⁺and TNF-α⁺CD8⁺T cells as well as effector memory T cells in the periphery lymph orangs and lungs of mice.Conclusions: We successfully established a humanized mouse model of ICI-related severe arthritis and pneumonitis with a higher frequency of TNF-α⁺T cells, which were significantly mitigated by anti-TNF-α treatment. Conceptually, ICI treatment can induce multiple autoimmune-like diseases in autoimmune-prone individuals and TNF-α⁺T cells may be therapeutic targets for intervention of immune-related arthritis and pneumonitis.

Objectives: Angiogenic T cells (Tang) are crucial in promoting angiogenesis, with the loss of CD28 serving as a marker for highly differentiated and senescent T cells. This study aims to investigate the characteristics and potential roles of CD8⁺CD28^null Tang in patients with ANCA-associated vasculitis (AAV). Methods: A cohort of AAV patients and matched healthy controls (HCs) were analyzed. Flow cytometry was used to assess the profiles of circulating CD8⁺CD28^null Tang. In vitro functional assays were performed to evaluate the pathogenic properties of CD8⁺CD28^null Tang. Results: CD8⁺CD28^null Tang levels were significantly higher in the peripheral blood of AAV patients compared to HCs, and their levels were further increased in AAV patients with MPO⁺, p-ANCA⁺, or interstitial lung disease compared to their respective control groups. Additionally, there was a positive correlation between both the percentage and absolute count of CD8⁺CD28^null Tang and the Birmingham Vasculitis Activity Score (BVAS). In patients with a good treatment response, both the percentage and absolute count of CD8⁺CD28^null Tang were significantly reduced, and this reduction was positively correlated with the decrease in BVAS scores. In vitro studies revealed that CD8⁺CD28^null Tang displayed enhanced chemotactic properties, induced apoptosis in human umbilical vein endothelial cells (HUVECs), and inhibited their proliferation, migration, and tube formation. Conclusions: AAV patients exhibit increased levels of circulating CD8⁺CD28^null Tang, which can be reduced following effective treatment. Furthermore, CD8⁺CD28^null Tang may contribute to the pathogenesis of AAV by promoting apoptosis and inhibiting the proliferation, migration, and tube formation of HUVECs.

CD147 is a T cell activation-associated molecule which is closely involved in the formation of the immune synapse (IS). However, the precise role of CD147 in T cell activation and IS formation remains unclear. In the present study, we demonstrated that CD147 translocated to the IS upon T cell activation and was primarily distributed in the peripheral super molecular cluster (p-SMAC). The knock down of CD147 expression in T cells, but not in B cells, impaired IS formation. CD147 participated in IS formation between T cells and different types of antigen-presenting cells (APCs), including macrophages and dendritic cells. Ligation of CD147 with its monoclonal antibody (mAb) HAb18 effectively inhibited T cell activation and IL-2 secretion. CD98, a critical molecule interacting with CD147, was distributed in IS in a CD147-dependent way. Phosphorylation levels of T cell receptor (TCR) related molecules, like ZAP-70, ERK, and cJun, were down-regulated by CD147 ligation, which is crucial for the interaction of CD147 and TCR signaling transduction. CD147 is indispensable for the formation of immune synapses and plays an important role in the regulation of its function.

Interstitial lung disease (ILD) represents a significant extra-articular complication associated with rheumatoid arthritis (RA), contributing substantially to the morbidity and mortality observed in affected patients. Despite its clinical relevance, the underlying mechanisms driving the pathogenesis of RA-ILD remain poorly understood, necessitating further investigation into the immunological factors that may play a role in this condition. This study aimed to elucidate the role of ST2⁺ regulatory T cells (Tregs) in the progression of RA-ILD. To achieve this, we developed a composite murine model that integrated collagen-induced arthritis (CIA) with intratracheal bleomycin (BLM) administration, thereby simulating the pathophysiological features of RA-ILD. Concurrently, using flow cytometric and artificial intelligence-based quantitative analysis of high-resolution computed tomography (HRCT), we analyzed a clinical cohort consisting of healthy controls, RA patients without ILD (RA-nonILD), and RA patients with ILD (RA-ILD). Histopathological assessment confirmed that the composite model exhibited exacerbated lung inflammation and fibrosis. Notably, flow cytometry revealed a marked expansion of ST2⁺ Tregs in both the lungs of CIA + BLM mice and the peripheral blood of RA-ILD patients. Moreover, quantitative HRCT analysis indicated a positive correlation between the frequency of ST2⁺ Tregs and fibrotic lung volume in patients. RA-ILD patients exhibited elevated serum levels of IL-33 and amphiregulin (AREG), which correlated with disease severity. In vitro studies further demonstrated that IL-33 stimulation significantly upregulated AREG expression at both the mRNA and protein levels in Tregs. These results highlight the potential involvement of the IL-33/ST2 axis in mediating a pathogenic Tregs response characterized by AREG production, thereby linking systemic autoimmunity to the progression of lung fibrosis in RA-ILD. Importantly, this study identifies the IL-33/ST2/AREG axis and ST2⁺ Tregs as promising biomarkers and therapeutic targets for RA-ILD, laying the groundwork for future mechanistic studies and translational research endeavors.