The nuclear factor ID3 endows macrophages with a potent anti-tumour activity

Convergent inducers and effectors of T cell paralysis in the tumour microenvironment

Tumorigenesis embodies the formation of a heterotypic tumour microenvironment (TME) that, among its many functions, enables the evasion of T cell-mediated immune responses. Remarkably, most TME cell types, including cancer cells, fibroblasts, myeloid cells, vascular endothelial cells and pericytes, can be stimulated to deploy immunoregulatory programmes. These programmes involve regulatory inducers (signals-in) and functional effectors (signals-out) that impair CD8+ and CD4+ T cell activity through cytokines, growth factors, immune checkpoints and metabolites. Some signals target specific cell types, whereas others, such as transforming growth factor-β (TGFβ) and prostaglandin E2 (PGE2), exert broad, pleiotropic effects; as signals-in, they trigger immunosuppressive programmes in most TME cell types, and as signals-out, they directly inhibit T cells and also modulate other cells to reinforce immunosuppression. This functional diversity and redundancy pose a challenge for therapeutic targeting of the immune-evasive TME. Fundamentally, the commonality of regulatory programmes aimed at abrogating T cell activity, along with paracrine signalling between cells of the TME, suggests that many normal cell types are hard-wired with latent functions that can be triggered to prevent inappropriate immune attack. This intrinsic capability is evidently co-opted throughout the TME, enabling tumours to evade immune destruction.

FOLR2+ macrophage depletion from intestinal metaplasia to early gastric cancer: single-cell sequencing insight into gastric cancer progression

BACKGROUND

The immune landscape associated with different subtypes of intestinal metaplasia (IM) and early gastric cancer (EGC) remains unclear. This study aimed to investigate the immune landscape of complete intestinal metaplasia (CIM), incomplete intestinal metaplasia (IIM), and EGC, as well as the underlying mechanisms of EGC progression.

METHODS

Gastric biopsy samples were collected from five patients with CIM, six patients with IIM, and four patients with EGC, followed by single-cell RNA sequencing. Multiplex immunohistochemical staining was employed to validate the samples from the aforementioned patients. To elucidate the potential mechanisms involved, in vitro coculture experiments were conducted using FOLR2+/FOLR2- macrophages and CD8+ T cells. Flow cytometry was utilized to investigate the biological functions of FOLR2+ macrophages in the progression of EGC.

RESULTS

Five subpopulations of macrophages were identified in CIM, IIM and EGC samples. FOLR2+ macrophages possess antitumor immune potential, and the proportion of FOLR2+ macrophage gradually decreased from the CIM stage to the IIM and EGC stages. FOLR2+ macrophages were significantly positively correlated with CD8+ T cells and activated the cytotoxicity of CD8+ T cells via antigen cross-presentation. Additionally, during the progression of EGC, epithelial cells progressively upregulated APP expression, thus inducing necroptosis of FOLR2+ macrophages via the APP‒TNFRSF21 axis.

CONCLUSIONS

Our work provides an understanding of the potential mechanisms underlying the malignant transformation of IM mediated by FOLR2+ macrophages.

Chimeric antigen receptor macrophages targeting c-MET(CAR-M-c-MET) inhibit pancreatic cancer progression and improve cytotoxic chemotherapeutic efficacy

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors. Macrophages are abundant in the tumor microenvironment, making them an attractive target for therapeutic intervention. While current immunotherapies, including immune checkpoint inhibition (ICI) and chimeric antigen receptor T (CAR-T) cells, have shown limited efficacy in pancreatic cancer, a novel approach involving chimeric antigen receptor macrophages (CAR-M) has, although promising, not been explored in pancreatic cancer. In this study, we first investigated the role of CAR-M cells targeting c-MET in pancreatic cancer.

METHODS

The effectiveness and rationality of c-MET as a target for CAR-M in pancreatic cancer were validated through bioinformatic analyses and immunohistochemical staining of samples from pancreatic cancer patients. We utilized flow cytometry and bioluminescence detection methods to demonstrate the specific binding and phagocytic killing effect of CAR-M on pancreatic cancer cells. Additionally, we observed the process of CAR-M engulfing pancreatic cancer cells using confocal microscopy and a long-term fluorescence live cell imaging system. In an in situ tumor model transplanted into NOD/SCID mice, we administered intraperitoneal injections of CAR-M to confirm its inhibitory function on pancreatic cancer. Furthermore, we validated these findings in human monocyte-derived macrophages (hMDM).

RESULTS

Bioinformatics and tumor tissue microarray analyses revealed significantly higher expression levels of c-MET in tumor tissues, compared to the paired peritumoral tissues, and higher c-MET expression correlated with worse patient survival. CAR-M cells were engineered using human monocytic THP-1 cell line and hMDM targeting c-MET (CAR-M-c-MET). The CAR-M-c-MET cells demonstrated highly specific binding to pancreatic cancer cells and exhibited more phagocytosis and killing abilities than the pro-inflammatory polarized control macrophages. In addition, CAR-M-c-MET cells synergized with various cytotoxic chemotherapeutic drugs. In a NOD/SCID murine model, intraperitoneally injected CAR-M-c-MET cells rapidly migrated to tumor tissue and substantially inhibited tumor growth, which did not lead to obvious side effects. Cytokine arrays and mRNA sequencing showed that CAR-M-c-MET produced higher levels of immune activators than control macrophages.

CONCLUSIONS

This study provides compelling evidence for the safety and efficacy of CAR-M therapy in treating pancreatic cancer. The results demonstrate that CAR-M-c-MET significantly suppresses pancreatic cancer progression and enhances the effectiveness of cytotoxic chemotherapy. Remarkably, no discernible side effects occur. Further clinical trials are warranted in human pancreatic cancer patients.

Alternations in inflammatory macrophage niche drive phenotypic and functional plasticity of Kupffer cells

Inflammatory signals lead to recruitment of circulating monocytes and induce their differentiation into pro-inflammatory macrophages. Therefore, whether blocking inflammatory monocytes can mitigate disease progression is being actively evaluated. Here, we employ multiple lineage-tracing models and show that monocyte-derived macrophages (mo-mac) are the major population of immunosuppressive, liver metastasis-associated macrophages (LMAM), while the proportion of Kupffer cells (KC) as liver-resident macrophages is diminished in metastatic nodules. Paradoxically, genetic ablation of mo-macs results in only a marginal decrease in LMAMs. Using a proliferation-recording system and a KC-tracing model in a monocyte-deficient background, we find that LMAMs can be replenished either via increased local macrophage proliferation or by promoting KC infiltration. In the latter regard, KCs undergo transient proliferation and exhibit substantial phenotypic and functional alterations through epigenetic reprogramming following the vacating of macrophage niches by monocyte depletion. Our data thus suggest that a simultaneous blockade of monocyte recruitment and macrophage proliferation may effectively target immunosuppressive myelopoiesis and reprogram the microenvironment towards an immunostimulatory state.

Transcriptional rewiring in CD8+ T cells: implications for CAR-T cell therapy against solid tumours

T cells engineered to express chimeric-antigen receptors (CAR-T cells) can effectively control relapsed and refractory haematological malignancies in the clinic. However, the successes of CAR-T cell therapy have not been recapitulated in solid tumours due to a range of barriers such as immunosuppression, poor infiltration, and tumour heterogeneity. Numerous strategies are being developed to overcome these barriers, which include improving culture conditions and manufacturing protocols, implementing novel CAR designs, and novel approaches to engineering the T cell phenotype. In this review, we describe the various emerging strategies to improve CAR T cell therapy for solid tumours. We specifically focus on new strategies to modulate cell function and fate that have precipitated from the growing knowledge of transcriptional circuits driving T cell differentiation, with the ultimate goal of driving more productive anti-tumour T cell immunity. Evidence shows that enrichment of particular phenotypic subsets of T cells in the initial cell product correlates to improved therapeutic responses and clinical outcomes. Furthermore, T cell exhaustion and poor persistence are major factors limiting therapeutic efficacy. The latest preclinical work shows that targeting specific master regulators and transcription factors can overcome these key barriers, resulting in superior T cell therapeutic products. This can be achieved by targeting key transcriptional circuits promoting memory-like phenotypes or sustaining key effector functions within the hostile tumour microenvironment. Additional discussion points include emerging considerations for the field such as (i) targeting permutations of transcription factors, (ii) transient expression systems, (iii) tissue specificity, and (iv) expanding this strategy beyond CAR-T cell therapy and cancer.

A spatiotemporal comparative analysis on tumor immune microenvironment characteristics between neoadjuvant chemotherapy and preoperative immunotherapy for ESCC

The average five-year survival rate for esophageal cancer, a common malignant tumor of the digestive system, is barely 20%. The majority of esophageal squamous cell carcinoma (ESCC) patients had already progressed to a locally advanced or even advanced stage at initial diagnosis, making routine surgery ineffective. Chemotherapy and immunotherapy are important neoadjuvant treatments for ESCC, however, it remains unknown how treatment will affect the immunological microenvironment, especially at the spatial level. Here, we presented the TME characters of ESCC from the temporal and spatial dimensions using scRNA-seq and ST, investigated the changes of immune cell clusters in the TME under neoadjuvant chemotherapy and preoperative immunotherapy, and explored the potential mechanisms. It was found that compared with chemotherapy, immunotherapy combined with chemotherapy increased the level of T cell proliferation, partially restored the function of exhausted T cells, induced the expansion of specific exhausted CD8 T cells, increased the production of dendritic cells (DCs), and supported the immune hot microenvironment of the tumor. We also found that CD52 and ID3 have potential as biomarkers of ESCC. Particularly, CD52 may be served as a predictor of the efficacy to screen the advantaged population of different regimens. Through multiple pathways, CAF2 and CAF5's antigen-presenting role affected the other fibroblast clusters, resulting in malignant transformation. We analyzed the immune microenvironment differences between the two regimens to provide a more thorough description of the ESCC microenvironment profile and serve as a foundation for customized neoadjuvant treatment of ESCC.

Immunomodulatory molecules in colorectal cancer liver metastasis

Colorectal cancer (CRC) ranks as the third most common cancer and the second leading cause of cancer-related deaths. According to clinical diagnosis and treatment, liver metastasis occurs in approximately 50 % of CRC patients, indicating a poor prognosis. The unique immune tolerance of the liver fosters an immunosuppressive tumor microenvironment (TME). In the context of tumors, numerous membrane and secreted proteins have been linked to tumor immune evasion as immunomodulatory molecules, but much remains unknown about how these proteins contribute to immune evasion in colorectal cancer liver metastasis (CRLM). This article reviews recently discovered membrane and secreted proteins with roles as both immunostimulatory and immunosuppressive molecules within the TME that influence immune evasion in CRC primary and metastatic lesions, particularly their mechanisms in promoting CRLM. This article also addresses screening strategies for identifying proteins involved in immune evasion in CRLM and provides insights into potential protein targets for treating CRLM.

Maintenance of homeostasis by TLR4 ligands

Immunotherapy is renowned for its capacity to elicit anti-infective and anti-cancer effects by harnessing immune responses to microbial components and bolstering innate healing mechanisms through a cascade of immunological reactions. Specifically, mammalian Toll-like receptors (TLRs) have been identified as key receptors responsible for detecting microbial components. The discovery of these mammalian Toll-like receptors has clarified antigen recognition by the innate immune system. It has furnished a molecular foundation for comprehending the interplay between innate immunity and its anti-tumor or anti-infective capabilities. Moreover, accumulating evidence highlights the crucial role of TLRs in maintaining tissue homeostasis. It has also become evident that TLR-expressing macrophages play a central role in immunity by participating in the clearance of foreign substances, tissue repair, and the establishment of new tissue. This macrophage network, centered on macrophages, significantly contributes to innate healing. This review will primarily delve into innate immunity, specifically focusing on substances targeting TLR4.