B-cell immune checkpoint TIM-1: a potential target for tumour immunotherapy

New insights into cancer immune checkpoints landscape from single-cell RNA sequencing

Immune checkpoint blockade (ICB) therapy represents a pivotal advancement in tumor immunotherapy by restoring the cytotoxic lymphocytes' anti-tumor activity through the modulation of immune checkpoint functions. Nevertheless, many patients experience suboptimal therapeutic outcomes, likely due to the immunosuppressive tumor microenvironment, drug resistance, and other factors. Single-cell RNA sequencing has assisted to precisely investigate the immune infiltration patterns before and after ICB treatment, enabling a high-resolution depiction of previously unrecognized functional interaction among immune checkpoints. This review addresses the heterogeneity between tumor microenvironments that respond to or resist ICB therapy, highlighting critical factors underlying the variation in immunotherapy efficacy and elucidating treatment failure. Furthermore, a comprehensive examination is provided of how specific ICBs modulate immune and tumor cells to achieve anti-tumor effects and generate treatment resistance, alongside a summary of emerging immune checkpoints identified as promising targets for cancer immunotherapy through single-cell RNA sequencing applications.

Distribution characteristics and prognostic value of TIM-1 in patients with lung adenocarcinoma

Background

T-cell immunoglobulin and mucin domain-containing protein 1 (TIM-1) has been identified as a promoter of tumor cell viability, migration, and invasion. However, the precise role and distribution characteristics of TIM-1 within the tumor microenvironment (TME) remain critical areas of investigation.

Methods

In this study, multiplex immunofluorescence (mIF) was performed on tissue slides from 126 patients with lung adenocarcinoma (LUAD) to investigate the distribution patterns of TIM-1 and the prognostic significance of three TIM-1 positive immune cell populations in both the primary tumor and tumor-draining lymph nodes (TDLN).

Results

Compared to the primary tumor, TIM-1+CD8+T cells and TIM-1+B cells exhibited significantly greater density in the TDLN (p<0.0001, p<0.0001 respectively). In the primary tumor, lower TIM-1+B cell density was associated with longer overall survival (OS) (mOS, 84 vs. 54 months; p<0.0001, HR=2.574) and disease-free survival (DFS) (mDFS, 53.0 vs. 23.1 months; p=0.018, HR=1.721). In the TDLN, lower TIM-1+B cell density was also correlated with longer OS (mOS, not reached vs. 64.7 months; p=0.0019, HR=2.3502) and DFS (mDFS, 68.5 vs. 28.9 months; p=0.016, HR=1.707). Higher TIM-1+B cell density in the TDLN was associated with a lower proportion of mature tertiary lymphoid structures (TLS) (p=0.0009, r=-0.3990) and increased density of TIM-1+B cells in the tumor was linked to reduced CD8+ T cell density (p=0.016, r=-0.2788).

Conclusions

Our findings confirm the immunosuppressive role of TIM-1+B cells in LUAD and suggest that TIM-1+B cells exert immune suppression by inhibiting TLS maturation and CD8+ T cell density. These findings highlight TIM-1+ B cells as a potential therapeutic target.

Immune Checkpoints in B Cells: Unlocking New Potentials in Cancer Treatment

B cells are crucial component of humoral immunity, and their role in the tumor immune microenvironment (TME) has garnered significant attention in recent years. These cells hold great potential and application prospects in the field of tumor immunotherapy. Research has demonstrated that the TME can remodel various B cell functions, including proliferation, differentiation, antigen presentation, and antibody production, thereby invalidating the anti-tumor effects of B cells. Concurrently, numerous immune checkpoints (ICs) on the surface of B cells are upregulated. Aberrant B-cell IC signals not only impair the function of B cells themselves, but also modulate the tumor-killing effects of other immune cells, ultimately fostering an immunosuppressive TME and facilitating tumor immune escape. Blocking ICs on B cells is beneficial for reversing the immunosuppressive TME and restoring anti-tumor immune responses. In this paper, the intricate connection between B-cell ICs and the TME is delved into, emphasizing the critical role of targeting B-cell ICs in anti-tumor immunity, which may provide valuable insights for the future development of tumor immunotherapy based on B cells.

The current understanding of the phenotypic and functional properties of human regulatory B cells (Bregs)

B cells can have a wide range of pro- and anti- inflammatory functions. A subset of B cells called regulatory B cells (Bregs) can potently suppress immune responses. Bregs have been shown to maintain immune homeostasis and modulate inflammatory responses. Bregs are an exciting cellular target across a range of diseases, including Breg induction in autoimmunity, allergy and transplantation, and Breg suppression in cancers and infection. Bregs exhibit a remarkable phenotypic heterogeneity, rendering their unequivocal identification a challenging task. The lack of a universally accepted and exclusive surface marker set for Bregs across various studies contributes to inconsistencies in their categorization. This review paper presents a comprehensive overview of the current understanding of the phenotypic and functional properties of human Bregs while addressing the persisting ambiguities and discrepancies in their characterization. Finally, the paper examines the promising therapeutic opportunities presented by Bregs as their immunomodulatory capacities have gained attention in the context of autoimmune diseases, allergic conditions, and cancer. We explore the exciting potential in harnessing Bregs as potential therapeutic agents and the avenues that remain open for the development of Breg-based treatment strategies.