Shining a LIGHT on myeloid cell targeted immunotherapy

The Function of B and T Lymphocyte Attenuator and Its Role in Transplantation

Immune checkpoints are important molecules that regulate the immune response, preventing its overactivation from causing tissue damage and autoimmune diseases. B and T lymphocyte attenuator (BTLA) plays an important role in regulating the activation and suppression of the immune response as part of a bidirectional signaling complex. The BTLA and its ligand herpesvirus entry mediator (HVEM) interaction transmits inhibitory signals that suppress the biological activity of T cells, B cells, and DCs. In addition, BTLA-HVEM can affect the induction of Treg cells, further suggesting its important role in immune regulation. Organ transplantation is the ultimate treatment option for many patients with end-stage organ failure. Transplant rejection can cause damage to the transplanted organ, which seriously affects the prognosis of patients. Therefore, we would like to explore the potential application value of the BTLA-HVEM interaction to exert an immunosuppressive function and thus attenuate transplant rejection. We first reviewed the structure and function of BTLA and HVEM, then summarized their research progress in organ transplantation, and further explored the directions of potential future applications and the challenges of current BTLA-HVEM applications.

From heterogeneity to prognosis: understanding the complexity of tertiary lymphoid structures in tumors

Tertiary lymphoid structures (TLSs) are aberrant lymphoid tissues found in persistent inflammatory settings, including malignancies, autoimmune disorders, and transplanted organs. The organization and architecture of TLS closely resemble that of secondary lymphoid organs (SLOs). The formation of TLS is an ongoing process, with varying structural features observed at different stages of maturation. The tumor microenvironment (TME) is a multifaceted milieu comprising cells, molecules, and extracellular matrix components in close proximity to the neoplasm. TLS within the TME have the capacity to actively elicit anti-tumor immune responses. TLSs exhibit tumor-specific and individual-specific characteristics, leading to varying immune responses towards tumor immunity based on their distinct cellular components, maturity levels, and spatial distribution. Cell interaction is the foundational elements of tumor immunity. Despite differences in the cellular composition of TLS, B cells and T cells are the main components of tumor-associated TLS。Recent research has highlighted the significance of diverse subtypes of B cells and T cells within TLSs in influencing the therapeutic outcomes and prognostic indicators of individual tumors. This review elucidates the diversity of TLS in terms of cellular composition, developmental stage, anatomical location, and the influence of cytokines on their initiation and progression. Furthermore, the article examines the involvement of B and T cells within TLS and the significance of TLS in relation to tumor prognosis.

High endothelial venules in the pleura: MECA-79 expression in mesothelioma, pleural metastasis and pleuritis

INTRODUCTION

High endothelial venules (HEVs) are vessels specialized in the extravasation of lymphocytes from the blood to the tissue implicated in the immune microenvironment of several tumors. Their presence has been never studied in the pleural tissue.

MATERIAL AND METHODS

We retrospectively studied 149 surgical pleural biopsies by immunohistochemistry for MECA-79 expression, a marker specifically recognizing HEVs. The tissues included 44 (44 %) inflammatory and 105 (56 %) neoplastic diseases. The latter corresponded to 34 (22.8 %) mesotheliomas and 71 (47.7 %) metastases from lung (n=50) or breast (n=21) primaries.

RESULTS

HEVs were present in 102 (68 %) of all pleural specimens with a mean number of foci containing HEVs of 13.33 (±20.64). Neoplastic pleural pathologies harbored HEVs in 73.3 % of the cases compared to the non-neoplastic pathologies which harbored HEVs in 56.8 % of the cases (p=0.048). Their presence did not differ between pulmonary or mammary metastasis (p=0.7).

CONCLUSION

We show for the first time that HEVs are present in the pleural cavity probably participating in the immune microenvironment of inflammatory and neoplastic pleural disease.

LTBR acts as a novel immune checkpoint of tumor-associated macrophages for cancer immunotherapy

Tumor-associated macrophages (TAMs) greatly contribute to immune checkpoint inhibitor (ICI) resistance of cancer. However, its underlying mechanisms and whether TAMs can be promising targets to overcome ICI resistance remain to be unveiled. Through integrative analysis of immune multiomics data and single-cell RNA-seq data (iMOS) in lung adenocarcinoma (LUAD), lymphotoxin β receptor (LTBR) is identified as a potential immune checkpoint of TAMs, whose high expression, duplication, and low methylation are correlated with unfavorable prognosis. Immunofluorescence staining shows that the infiltration of LTBR+ TAMs is associated with LUAD stages, immunotherapy failure, and poor prognosis. Mechanistically, LTΒR maintains immunosuppressive activity and M2 phenotype of TAMs by noncanonical nuclear factor kappa B and Wnt/β-catenin signaling pathways. Macrophage-specific knockout of LTBR hinders tumor growth and prolongs survival time via blocking TAM immunosuppressive activity and M2 phenotype. Moreover, TAM-targeted delivery of LTΒR small interfering RNA improves the therapeutic effect of ICI via reversing TAM-mediated immunosuppression, such as boosting cytotoxic CD8+ T cells and inhibiting granulocytic myeloid-derived suppressor cells infiltration. Taken together, we bring forth an immune checkpoint discovery pipeline iMOS, identify LTBR as a novel immune checkpoint of TAMs, and propose a new immunotherapy strategy by targeting LTBR+ TAMs.

Lipid-Encapsulated mRNAs Encoding Complex Fusion Proteins Potentiate Antitumor Immune Responses

Lipid nanoparticle (LNP)-encapsulated mRNA has been used for in vivo production of several secreted protein classes, such as IgG, and has enabled the development of personalized vaccines in oncology. Establishing the feasibility of delivering complex multispecific modalities that require higher-order structures important for their function could help expand the use of mRNA/LNP biologic formulations. Here, we evaluated whether in vivo administration of mRNA/LNP formulations of SIRPα-Fc-CD40L and TIGIT-Fc-LIGHT could achieve oligomerization and extend exposure, on-target activity, and antitumor responses comparable with that of the corresponding recombinant fusion proteins. Intravenous infusion of the formulated LNP-encapsulated mRNAs led to rapid and sustained production of functional hexameric proteins in vivo, which increased the overall exposure relative to the recombinant protein controls by ∼28 to 140 fold over 96 hours. High concentrations of the mRNA-encoded proteins were also observed in secondary lymphoid organs and within implanted tumors, with protein concentrations in tumors up to 134-fold greater than with the recombinant protein controls 24 hours after treatment. In addition, SIRPα-Fc-CD40L and TIGIT-Fc-LIGHT mRNAs induced a greater increase in antigen-specific CD8+ T cells in the tumors. These mRNA/LNP formulations were well tolerated and led to a rapid increase in serum and intratumoral IL2, delayed tumor growth, extended survival, and outperformed the activities of benchmark mAb controls. Furthermore, the mRNA/LNPs demonstrated improved efficacy in combination with anti-PD-L1 relative to the recombinant fusion proteins. These data support the delivery of complex oligomeric biologics as mRNA/LNP formulations, where high therapeutic expression and exposure could translate into improved patient outcomes.

SIGNIFICANCE

Lipid nanoparticle-encapsulated mRNA can efficiently encode complex fusion proteins encompassing immune checkpoint blockers and costimulators that functionally oligomerize in vivo with extended pharmacokinetics and durable exposure to induce potent antitumor immunity.

Epigenome-Driven Strategies for Personalized Cancer Immunotherapy

Fighting cancer remains one of the greatest challenges for science in the 21st century. Advances in immunotherapy against different types of cancer have greatly contributed to the treatment, remission, and cure of patients. In this context, knowledge of epigenetic phenomena, their relationship with tumor cells and how the immune system can be epigenetically modulated represent some of the greatest advances in the development of anticancer therapies. Epigenetics is a rapidly growing field that studies how environmental factors can affect gene expression without altering DNA sequence. Epigenomic changes include DNA methylation, histone modifications, and non-coding RNA regulation, which impact cellular function. Epigenetics has shown promise in developing cancer therapies, such as immunotherapy, which aims to stimulate the immune system to attack cancer cells. For example, PD-1 and PD-L1 are biomarkers that regulate the immune response to cancer cells and recent studies have shown that epigenetic modifications can affect their expression, potentially influencing the efficacy of immunotherapy. New therapies targeting epigenetic modifications, such as histone deacetylases and DNA methyltransferases, are being developed for cancer treatment, and some have shown promise in preclinical studies and clinical trials. With growing understanding of epigenetic regulation, we can expect more personalized and effective cancer immunotherapies in the future. This review highlights key advances in the use of epigenetic and epigenomic tools and modern immuno-oncology strategies to treat several types of tumors.

Reconciling intrinsic properties of activating TNF receptors by native ligands versus synthetic agonists

The extracellular domain of tumor necrosis factor receptors (TNFR) generally require assembly into a homotrimeric quaternary structure as a prerequisite for initiation of signaling via the cytoplasmic domains. TNF receptor homotrimers are natively activated by similarly homo-trimerized TNF ligands, but can also be activated by synthetic agonists including engineered antibodies and Fc-ligand fusion proteins. A large body of literature from pre-clinical models supports the hypothesis that synthetic agonists targeting a diverse range of TNF receptors (including 4-1BB, CD40, OX40, GITR, DR5, TNFRSF25, HVEM, LTβR, CD27, and CD30) could amplify immune responses to provide clinical benefit in patients with infectious diseases or cancer. Unfortunately, however, the pre-clinical attributes of synthetic TNF receptor agonists have not translated well in human clinical studies, and have instead raised fundamental questions regarding the intrinsic biology of TNF receptors. Clinical observations of bell-shaped dose response curves have led some to hypothesize that TNF receptor overstimulation is possible and can lead to anergy and/or activation induced cell death of target cells. Safety issues including liver toxicity and cytokine release syndrome have also been observed in humans, raising questions as to whether those toxicities are driven by overstimulation of the targeted TNF receptor, a non-TNF receptor related attribute of the synthetic agonist, or both. Together, these clinical findings have limited the development of many TNF receptor agonists, and may have prevented generation of clinical data which reflects the full potential of TNF receptor agonism. A number of recent studies have provided structural insights into how different TNF receptor agonists bind and cluster TNF receptors, and these insights aid in deconvoluting the intrinsic biology of TNF receptors with the mechanistic underpinnings of synthetic TNF receptor agonist therapeutics.