BTNL2-Ig Protein Attenuates Type 1 Diabetes in Non-Obese Diabetic (NOD) Mice

Emerging strategies for treating autoimmune disease with genetically modified dendritic cells

Gene editing of living cells has become a crucial tool in medical research, enabling scientists to address fundamental biological questions and develop novel strategies for disease treatment. This technology has particularly revolutionized adoptive transfer cell therapy products, leading to significant advancements in tumor treatment and offering promising outcomes in managing transplant rejection, autoimmune disorders, and inflammatory diseases. While recent clinical trials have demonstrated the safety of tolerogenic dendritic cell (TolDC) immunotherapy, concerns remain regarding its effectiveness. This review aims to discuss the application of gene editing techniques to enhance the tolerance function of dendritic cells (DCs), with a particular focus on preclinical strategies that are currently being investigated to optimize the tolerogenic phenotype and function of DCs. We explore potential approaches for in vitro generation of TolDCs and provide an overview of emerging strategies for modifying DCs. Additionally, we highlight the primary challenges hindering the clinical adoption of TolDC therapeutics and propose future research directions in this field.

BTNL2 promotes colitis-associated tumorigenesis in mice by regulating IL-22 production

Interleukin 22 (IL-22) has an important role in colorectal tumorigenesis and many colorectal diseases such as inflammatory bowel disease and certain infections. However, the regulation of IL-22 production in the intestinal system is still unclear. Here, we present evidence that butyrophilin-like protein 2 (BTNL2) is required for colorectal IL-22 production, and BTNL2 knockout mice show decreased colonic tumorigenesis and more severe colitis phenotypes than control mice due to defective production of IL-22. Mechanistically, BTNL2 acts on group 3 innate lymphoid cells (ILC3s), CD4+ T cells, and γδ T cells to promote the production of IL-22. Importantly, we find that a monoclonal antibody against BTNL2 attenuates colorectal tumorigenesis in mice and that the mBTNL2-Fc recombinant protein has a therapeutic effect in a dextran sulfate sodium (DSS)-induced colitis model. This study not only identifies a regulatory mechanism of IL-22 production in the colorectal system but also provides a potential therapeutic target for the treatment of human colorectal cancer and inflammatory bowel diseases.

Identification of TAPBPL as a novel negative regulator of T-cell function

T cell stimulatory and inhibitory molecules are critical for the regulation of immune responses. In this study, we identify a novel T cell co‐inhibitory molecule TAPBPL, whose amino acid sequence shares homology with known B7 family members. TAPBPL protein is expressed on resting and activated T cells, B cells, monocytes, and dendritic cells (DCs), as well as on some tumor tissues. The putative TAPBPL receptor is expressed on activated CD4 and CD8 T cells. A soluble recombinant human TAPBPL‐IgG Fc (hTAPBPL‐Ig) fusion protein inhibits the proliferation, activation, and cytokine production of both mouse and human T cells in vitro. In vivo administration of hTAPBPL‐Ig protein attenuates experimental autoimmune encephalomyelitis (EAE) in mice. Furthermore, an anti‐TAPBPL monoclonal antibody neutralizes the inhibitory activity of hTAPBPL‐Ig on T cells, enhances antitumor immunity, and inhibits tumor growth in animal models. Our results suggest that therapeutic intervention of the TAPBPL inhibitory pathway may represent a new strategy to modulate T cell‐mediated immunity for the treatment of cancer, infections, autoimmune diseases, and transplant rejection.

Accelerator or Brake: Immune Regulators in Malaria

Malaria is a life-threatening infectious disease, affecting over 250 million individuals worldwide each year, eradicating malaria has been one of the greatest challenges to public health for a century. Growing resistance to anti-parasitic therapies and lack of effective vaccines are major contributing factors in controlling this disease. However, the incomplete understanding of parasite interactions with host anti-malaria immunity hinders vaccine development efforts to date. Recent studies have been unveiling the complexity of immune responses and regulators against Plasmodium infection. Here, we summarize our current understanding of host immune responses against Plasmodium-derived components infection and mainly focus on the various regulatory mechanisms mediated by recent identified immune regulators orchestrating anti-malaria immunity.

Structural Insights into N-terminal IgV Domain of BTNL2, a T Cell Inhibitory Molecule, Suggests a Non-canonical Binding Interface for Its Putative Receptors

T cell costimulation is mediated by the interaction of a number of receptors and ligands present on the surface of the T cell and antigen-presenting cell, respectively. Stimulatory or inhibitory signals from these receptor-ligand interactions work in tandem to preserve immune homeostasis. BTNL2 is a type-1 membrane protein that provides inhibitory signal to T cells and plays an important role in several inflammatory and autoimmune diseases. Therefore, manipulation of the molecular interaction of BTNL2 with its putative receptor could provide strategies to restore immune homeostasis in these diseases. Hence, it is imperative to study the structural characteristics of this molecule, which will provide important insights into its function as well. In this study, the membrane-distal ectodomain of murine BTNL2 was expressed in bacteria as inclusion bodies, refolded in vitro and purified for functional and structural characterization. The domain is monomeric in solution as demonstrated by size-exclusion chromatography and analytical ultracentrifugation, and also binds to its putative receptor on naïve B cells and activated T cell subsets. Importantly, for the first time, we report the structure of BTNL2 as determined by solution NMR spectroscopy and also the picosecond-nanosecond timescale backbone dynamics of this domain. The N-terminal ectodomain of BTNL2, which was able to inhibit T cell function as well, exhibits distinctive structural features. The N-terminal ectodomain of BTNL2 has a significantly reduced surface area in the front sheet due to the non-canonical conformation of the CC' loop, which provides important insights into the recognition of its presently unknown binding partner.

The Role of B7 Family Molecules in Maternal-Fetal Immunity

Pregnancy is a complex but well-arranged process, and a healthy fetus requires immune privilege and surveillance in the presence of paternally derived antigens. Maternal and fetal cells interact at the maternal–fetal interface. The upregulation and downregulation of maternal immunity executed by the leukocyte population predominantly depend on the activity of decidual natural killer cells and trophoblasts and are further modulated by a series of duplex signals. The B7 family, which consists of B7-1, B7-2, B7-H1, B7-DC, B7-H2, B7-H3, B7-H4, B7-H5, BTNL2, B7-H6, and B7-H7, is one of the most characterized and widely distributed signaling molecule superfamilies and conducts both stimulatory and inhibitory signals through separate interactions. In particular, the roles of B7-1, B7-2, B7-H1, and their corresponding receptors in the progression of normal pregnancy and some pregnancy complications have been extensively studied. Together with the TCR–MHC complex, B7 and its receptors play a critical role in cell proliferation and cytokine secretion. Depending on this ligand–receptor crosstalk, the balance between the tolerance and rejection of the fetus is perfectly maintained. This review aims to provide an overview of the current knowledge of the B7 family and its functions in regulating maternal–fetal immunity through individual interactions.