CD169(+) Macrophages in Primary Breast Tumors Associate with Tertiary Lymphoid Structures, T(regs) and a Worse Prognosis for Patients with Advanced Breast Cancer

Altered immune signatures in breast cancer lymph nodes with metastases revealed by spatial proteome analyses

BACKGROUND

Metastasis to lymph nodes is strongly associated with reduced survival in breast cancer patients. To increase the understanding on how lymph node metastasis impairs the local immune response in affected lymph nodes, we here studied spatial proteomic changes of critical lymph node immune populations in uninvolved lymph nodes (UnLN) and paired lymph nodes with metastases (LNM) from five breast cancer patients.

METHODS

The proteome was analyzed for cortical lymphocyte compartments, subcapsular sinus (SCS) and medullary sinus (MS) CD169+ macrophages, using the Digital Spatial Profiling (DSP) platform from NanoString.

RESULTS

Our results identified a stable proteome of SCS CD169+ macrophages in LNM, with the exception for downregulation of the anti-apoptotic protein Bcl-xL and FAPα, but a clear reduction in numbers of SCS CD169+ macrophages in LNM. In contrast, the proteome of MS CD169+ macrophages, B-cell compartments and interfollicular T-cells showed altered immune signatures in LNM, indicating that the decline in SCS CD169+ macrophages coincide with a malfunction in the local, anti-tumor immune responses.

CONCLUSIONS

The findings from our study support the notion that metastasis to lymph nodes in breast cancer patients modifies local immune responses. These changes may contribute to explain unsuccessful therapeutic responses, and thereby worsened prognosis, for breast cancer patients with LNM.

Exploring CD169+ Macrophages as Key Targets for Vaccination and Therapeutic Interventions

CD169 is a sialic acid-binding immunoglobulin-like lectin (Siglec-1, sialoadhesin) that is expressed by subsets of tissue-resident macrophages and circulating monocytes. This receptor interacts with α2,3-linked Neu5Ac on glycoproteins as well as glycolipids present on the surface of immune cells and pathogens. CD169-expressing macrophages exert tissue-specific homeostatic functions, but they also have opposing effects on the immune response. CD169+ macrophages act as a pathogen filter, protect against infectious diseases, and enhance adaptive immunity, but at the same time pathogens also exploit them to enable further dissemination. In cancer, CD169+ macrophages in tumor-draining lymph nodes are correlated with better clinical outcomes. In inflammatory diseases, CD169 expression is upregulated on monocytes and on monocyte-derived macrophages and this correlates with the disease state. Given their role in promoting adaptive immunity, CD169+ macrophages are currently investigated as targets for vaccination strategies against cancer. In this review, we describe the studies investigating the importance of CD169 and CD169+ macrophages in several disease settings and the vaccination strategies currently under investigation.

An Introduction to Tertiary Lymphoid Structures in Cancer

Immunotherapy has revolutionized therapeutics for cancer patients, which signifies the importance of effective antitumor immunity in combatting cancer. However, the benefit of immunotherapies is limited to specific patient populations and tumor types, suggesting the overt need for new immunotherapeutic targets. Tertiary lymphoid structures (TLS) are ectopic lymph node-like structures that develop at the sites of chronic inflammation such as cancer. TLS are correlated with favorable clinical outcomes across multiple solid tumors and are associated with increased tumor-infiltrating lymphocytes (TILs), particularly effector memory CD8+ T cells. Despite strong clinical data in humans, there are still major knowledge gaps on the function of TLS in cancer. Herein, we highlight the known biology and clinical impact of TLS, which offer further evidence to harness TLS for improved immunotherapeutics.

Macrophages and tertiary lymphoid structures as indicators of prognosis and therapeutic response in cancer patients

Tertiary lymphoid structures (TLS) can reflect cancer prognosis and clinical outcomes in various tumour tissues. Tumour-associated macrophages (TAMs) are indispensable components of the tumour microenvironment and play crucial roles in tumour development and immunotherapy. TAMs are associated with TLS induction via the modulation of the T cell response, which is a major component of the TLS. Despite their important roles in cancer immunology, the subtypes of TAMs that influence TLS and their correlation with prognosis are not completely understood. Here, we provide novel insights into the role of TAMs in regulating TLS formation. Furthermore, we discuss the prognostic value of these TAM subtypes and TLS, as well as the current antitumour therapies for inducing TLS. This study highlights an entirely new field of TLS regulation that may lead to the development of an innovative perspective on immunotherapy for cancer treatment.

Tertiary lymphoid structures in diseases: immune mechanisms and therapeutic advances

Tertiary lymphoid structures (TLSs) are defined as lymphoid aggregates formed in non-hematopoietic organs under pathological conditions. Similar to secondary lymphoid organs (SLOs), the formation of TLSs relies on the interaction between lymphoid tissue inducer (LTi) cells and lymphoid tissue organizer (LTo) cells, involving multiple cytokines. Heterogeneity is a distinguishing feature of TLSs, which may lead to differences in their functions. Growing evidence suggests that TLSs are associated with various diseases, such as cancers, autoimmune diseases, transplant rejection, chronic inflammation, infection, and even ageing. However, the detailed mechanisms behind these clinical associations are not yet fully understood. The mechanisms by which TLS maturation and localization affect immune function are also unclear. Therefore, it is necessary to enhance the understanding of TLS development and function at the cellular and molecular level, which may allow us to utilize them to improve the immune microenvironment. In this review, we delve into the composition, formation mechanism, associations with diseases, and potential therapeutic applications of TLSs. Furthermore, we discuss the therapeutic implications of TLSs, such as their role as markers of therapeutic response and prognosis. Finally, we summarize various methods for detecting and targeting TLSs. Overall, we provide a comprehensive understanding of TLSs and aim to develop more effective therapeutic strategies.

Tertiary lymphoid structures in cancer: immune mechanisms and clinical implications

Cancer is a major cause of death globally, and traditional treatments often have limited efficacy and adverse effects. Immunotherapy has shown promise in various malignancies but is less effective in tumors with low immunogenicity or immunosuppressive microenvironment, especially sarcomas. Tertiary lymphoid structures (TLSs) have been associated with a favorable response to immunotherapy and improved survival in cancer patients. However, the immunological mechanisms and clinical significance of TLS in malignant tumors are not fully understood. In this review, we elucidate the composition, neogenesis, and immune characteristics of TLS in tumors, as well as the inflammatory response in cancer development. An in-depth discussion of the unique immune characteristics of TLSs in lung cancer, breast cancer, melanoma, and soft tissue sarcomas will be presented. Additionally, the therapeutic implications of TLS, including its role as a marker of therapeutic response and prognosis, and strategies to promote TLS formation and maturation will be explored. Overall, we aim to provide a comprehensive understanding of the role of TLS in the tumor immune microenvironment and suggest potential interventions for cancer treatment.

Macrophage heterogeneity and its interactions with stromal cells in tumour microenvironment

Macrophages and tumour stroma cells account for the main cellular components in the tumour microenvironment (TME). Current advancements in single-cell analysis have revolutionized our understanding of macrophage diversity and macrophage-stroma interactions. Accordingly, this review describes new insight into tumour-associated macrophage (TAM) heterogeneity in terms of tumour type, phenotype, metabolism, and spatial distribution and presents the association between these factors and TAM functional states. Meanwhile, we focus on the immunomodulatory feature of TAMs and highlight the tumour-promoting effect of macrophage-tumour stroma interactions in the immunosuppressive TME. Finally, we summarize recent studies investigating macrophage-targeted therapy and discuss their therapeutic potential in improving immunotherapy by alleviating immunosuppression.

Heterogeneity of tertiary lymphoid structures in cancer

The success of immunotherapy approaches, such as immune checkpoint blockade and cellular immunotherapy with genetically modified lymphocytes, has firmly embedded the immune system in the roadmap for combating cancer. Unfortunately, the majority of cancer patients do not yet benefit from these therapeutic approaches, even when the prognostic relevance of the immune response in their tumor entity has been demonstrated. Therefore, there is a justified need to explore new strategies for inducing anti-tumor immunity. The recent connection between the formation of ectopic lymphoid aggregates at tumor sites and patient prognosis, along with an effective anti-tumor response, suggests that manipulating the occurrence of these tertiary lymphoid structures (TLS) may play a critical role in activating the immune system against a growing tumor. However, mechanisms governing TLS formation and a clear understanding of their substantial heterogeneity are still lacking. Here, we briefly summarize the current state of knowledge regarding the mechanisms driving TLS development, outline the impact of TLS heterogeneity on clinical outcomes in cancer patients, and discuss appropriate systems for modeling TLS heterogeneity that may help identify new strategies for inducing protective TLS formation in cancer patients.

Tumor macrophage functional heterogeneity can inform the development of novel cancer therapies

Macrophages represent a key component of the tumor microenvironment (TME) and are largely associated with poor prognosis. Therapeutic targeting of macrophages has historically focused on inhibiting their recruitment or reprogramming their phenotype from a protumor (M2-like) to an antitumor (M1-like) one. Unfortunately, this approach has not provided clinical breakthroughs that have changed practice. Emerging studies utilizing single-cell RNA-sequencing (scRNA-seq) and spatial transcriptomics have improved our understanding of the ontogeny, phenotype, and functional plasticity of macrophages. Overlaying the wealth of current information regarding macrophage molecular subtypes and functions has also identified novel therapeutic vulnerabilities that might drive better control of tumor-associated macrophages (TAMs). Here, we discuss the functional profiling of macrophages and provide an update of novel macrophage-targeted therapies in development.

Transcriptome and Metabolome Analyses Reveal the Mechanism of Corpus Luteum Cyst Formation in Pigs

Corpus luteum cysts are a serious reproductive disorder that affects the reproductive performance of sows. In this study, transcriptome and metabolome datasets of porcine normal and cyst luteal granulosa cells were generated to explore the molecular mechanism of luteal cyst formation. We obtained 28.9 Gb of high-quality transcriptome data from luteum tissue samples and identified 1048 significantly differentially expressed genes between the cyst and normal corpus luteum samples. Most of the differentially expressed genes were involved in cancer and immune signaling pathways. Furthermore, 22,622 information-containing positive and negative ions were obtained through gas chromatography-mass spectrometry, and 1106 metabolites were successfully annotated. Important differentially abundant metabolites and pathways were identified, among which abnormal lipid and choline metabolism were involved in the formation of luteal cysts. The relationships between granulosa cells of luteal cysts and cancer, immune-related signaling pathways, and abnormalities of lipid and choline metabolism were elaborated, providing new entry points for studying the pathogenesis of porcine luteal cysts.

Breast cancer associated CD169+ macrophages possess broad immunosuppressive functions but enhance antibody secretion by activated B cells

CD169⁺ resident macrophages in lymph nodes of breast cancer patients are for unknown reasons associated with a beneficial prognosis. This contrasts CD169⁺ macrophages present in primary breast tumors (CD169⁺ TAMs), that correlate with a worse prognosis. We recently showed that these CD169⁺ TAMs were associated with tertiary lymphoid structures (TLSs) and T_regs in breast cancer. Here, we show that CD169⁺ TAMs can be monocyte-derived and express a unique mediator profile characterized by type I IFNs, CXCL10, PGE₂ and inhibitory co-receptor expression pattern. The CD169⁺ monocyte-derived macrophages (CD169⁺ Mo-M) possessed an immunosuppressive function in vitro inhibiting NK, T and B cell proliferation, but enhanced antibody and IL6 secretion in activated B cells. Our findings indicate that CD169⁺ Mo-M in the primary breast tumor microenvironment are linked to both immunosuppression and TLS functions, with implications for future targeted Mo-M therapy.

Unraveling the Immune Microenvironment in Classic Hodgkin Lymphoma: Prognostic and Therapeutic Implications

Classic Hodgkin lymphoma (cHL) is a lymphoid neoplasm composed of rare neoplastic Hodgkin and Reed-Sternberg (HRS) cells surrounded by a reactive tumor microenvironment (TME) with suppressive properties against anti-tumor immunity. TME is mainly composed of T cells (CD4 helper, CD8 cytotoxic and regulatory) and tumor-associated macrophages (TAMs), but the impact of these cells on the natural course of the disease is not absolutely understood. TME contributes to the immune evasion of neoplastic HRS cells through the production of various cytokines and/or the aberrant expression of immune checkpoint molecules in ways that have not been fully understood yet. Herein, we present a comprehensive review of findings regarding the cellular components and the molecular features of the immune TME in cHL, its correlation with treatment response and prognosis, as well as the potential targeting of the TME with novel therapies. Among all cells, macrophages appear to be a most appealing target for immunomodulatory therapies, based on their functional plasticity and antitumor potency.