C-type lectin receptor Dectin-1 blockade on tumour-associated macrophages improves anti-PD-1 efficacy in gastric cancer

Modulating pro-fibrotic macrophages using yeast beta-glucan microparticles prepared by Pressurized Gas eXpanded liquid (PGX) Technology®

Pro-fibrotic M2-like macrophages are widely implicated in the pathogenesis and progression of lung fibrosis due to their production of pro-fibrotic growth factors and cytokines. Yeast beta-glucan (YBG) microparticles have shown potential as immunomodulators that can convert macrophage polarization from a pro-fibrotic phenotype to an anti-fibrotic phenotype through the engagement of the Dectin-1 receptor. However, the processing conditions used to fabricate YBG microparticles can lead to unpredictable immunomodulatory effects. Herein, we report the use of Pressurized Gas eXpanded liquids (PGX) Technology® to fabricate YBG (PGX-YBG) microparticles with higher surface areas, lower densities, and smaller and more uniform size distributions compared to commercially available spray-dried YBGs. PGX-YBG is shown to activate Dectin-1 more efficiently in vitro while avoiding significant TLR 2/4 activation. Furthermore, PGX-YBG microparticles effectively modulate M2-like fibrosis-inducing murine and human macrophages into fibrosis-suppressing macrophages both in vitro as well as in ex vivo precision-cut murine lung slices, suggesting their potential utility as a therapeutic for addressing a broad spectrum of fibrotic end-point lung diseases.

New insights into SYK targeting in solid tumors

Spleen tyrosine kinase (SYK) is predominantly expressed in hematopoietic cells and has been extensively studied for its pivotal role in B cell malignancies and autoimmune diseases. In epithelial solid tumors, SYK shows a paradoxical role, acting as a tumor suppressor in some cancers while driving tumor growth in others. Recent preclinical studies have identified the role of SYK in the tumor microenvironment (TME), revealing that SYK signaling in immune cells, especially B cells, and myeloid cells, promote immunosuppression, tumor growth, and metastasis across various solid tumors. This review explores the emerging roles of SYK in solid tumors, the mechanisms of SYK activation, and findings from preclinical and clinical studies of SYK inhibitors as either standalone treatments or in combination with immunotherapy or chemotherapy for solid tumors.

Tumor-associated macrophages within the immunological milieu: An emerging focal point for therapeutic intervention

Tumor-associated macrophages play an important role in the tumor immune microenvironment, and regulating the function of tumor-associated macrophages has important therapeutic potential in tumor therapy. Mature macrophages could migrate to the tumor microenvironment, influencing multiple factors such as tumor cell proliferation, invasion, metastasis, extracellular matrix remodeling, immune suppression, and drug resistance. As a major component of the tumor microenvironment, tumor-associated macrophages crosstalk with other immune cells. Currently, tumor-associated macrophages have garnered considerable attention in tumor therapy, broadening the spectrum of drug selection to some extent, thereby aiding in mitigating the prevailing clinical drug resistance dilemma. This article summarizes the recent advances in tumor-associated macrophages concerning immunology, drug targeting mechanisms for tumor-associated macrophages treatment, new developments, and existing challenges, offering insights for future therapeutic approaches. In addition, this paper summarized the impact of tumor-associated macrophages on current clinical therapies, discussed the advantages and disadvantages of targeted tumor-associated macrophages therapy compared with existing tumor therapies, and predicted and discussed the future role of targeted tumor-associated macrophages therapy and the issues that need to be focused on.

Secondary Sites of the C-type Lectin-Like Fold

C-type lectins are a large superfamily of proteins involved in a multitude of biological processes. In particular, their involvement in immunity and homeostasis has rendered them attractive targets for diverse therapeutic interventions. They share a characteristic C-type lectin-like domain whose adaptability enables them to bind a broad spectrum of ligands beyond the originally defined canonical Ca2+-dependent carbohydrate binding. Together with variable domain architecture and high-level conformational plasticity, this enables C-type lectins to meet diverse functional demands. Secondary sites provide another layer of regulation and are often intricately linked to functional diversity. Located remote from the canonical primary binding site, secondary sites can accommodate ligands with other physicochemical properties and alter protein dynamics, thus enhancing selectivity and enabling fine-tuning of the biological response. In this review, we outline the structural determinants allowing C-type lectins to perform a large variety of tasks and to accommodate the ligands associated with it. Using the six well-characterized Ca2+-dependent and Ca2+-independent C-type lectin receptors DC-SIGN, langerin, MGL, dectin-1, CLEC-2 and NKG2D as examples, we focus on the characteristics of non-canonical interactions and secondary sites and their potential use in drug discovery endeavors.

Myeloid C-type lectin receptors in innate immune recognition

C-type lectin receptors (CLRs) expressed by myeloid cells constitute a versatile family of receptors that play a key role in innate immune recognition. Myeloid CLRs exhibit a remarkable ability to recognize an extensive array of ligands, from carbohydrates and beyond, and encompass pattern-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and markers of altered self. These receptors, classified into distinct subgroups, play pivotal roles in immune recognition and modulation of immune responses. Their intricate signaling pathways orchestrate a spectrum of cellular responses, influencing processes such as phagocytosis, cytokine production, and antigen presentation. Beyond their contributions to host defense in viral, bacterial, fungal, and parasitic infections, myeloid CLRs have been implicated in non-infectious diseases such as cancer, allergies, and autoimmunity. A nuanced understanding of myeloid CLR interactions with endogenous and microbial triggers is starting to uncover the context-dependent nature of their roles in innate immunity, with implications for therapeutic intervention.

NKG2A+CD8+ T cells infiltration determines immunosuppressive contexture and inferior response to immunotherapy in clear cell renal cell carcinoma

BACKGROUND

Immunotherapy is gaining momentum, but current treatments have limitations in terms of beneficiaries. Clear cell renal cell carcinoma (ccRCC) harbors the highest expression of human leukocyte antigen E (HLA-E), ligand of NKG2A, among all solid tumors. In this study, we aim to investigate the role of NKG2A+CD8+ T cells in tumor microenvironment and its potential as a novel target in ccRCC.

METHODS

This study included four independent cohorts, including 234 patients from Zhongshan cohort (ZSHC) who underwent partial or radical nephrectomy at Zhongshan Hospital, and 117 metastatic patients from metastatic Zhongshan cohort (ZSHC-metastatic renal cell carcinoma) who were treated with immune checkpoint inhibitor or tyrosine kinase inhibitor alone. We also incorporated a cohort of 530 patients diagnosed with ccRCC from The Cancer Genome Atlas (referred to as TCGA-kidney renal clear cell carcinoma) and 311 patients from CheckMate cohort for bioinformatics exploration and hypothesis validation. Fresh surgical specimens from 15 patients who underwent ccRCC surgery at Zhongshan Hospital were collected for flow cytometry analysis. Another 10 fresh surgical specimens were used to investigate the therapeutic potential of NKG2A blockade after in vitro intervention. The infiltration of NKG2A+CD8+ T cells was assessed using immunohistochemical staining, flow cytometry, and immunofluorescence staining in ZSHC cohort.

RESULTS

Patients with higher infiltration of NKG2A+CD8+ T cells in ccRCC exhibited shorter overall survival and resistance to immunotherapy. NKG2A+CD8+ T cells expressed upregulated checkpoint molecules and displayed impaired effector functions, along with tissue-residency characteristics. Combination of programmed cell death protein-1 (PD-1) blockade and NKG2A blockade demonstrated an enhanced capability in reactivating CD8+ T cells effector functions.

CONCLUSION

Intense infiltration of NKG2A+CD8+ T cells were associated with poorer prognosis and response to immunotherapy. NKG2A blockade combined with current immunotherapy exhibited a robust ability to reactivate CD8+ T cells effector functions.

Tumour-associated macrophages in gastric cancer: From function and mechanism to application

BACKGROUND

Gastric cancer (GC) is a malignant tumour, with high morbidity and mortality rates worldwide. The occurrence and development of GC is a complex process involving genetic changes in tumour cells and the influence of the surrounding tumour microenvironment (TME). Accumulative evidence shows that tumour-associated macrophages (TAMs) play a vital role in GC, acting as plentiful and active infiltrating inflammatory cells in the TME.

MAIN BODY

In this review, the different functions and mechanisms of TAMs in GC progression, including the conversion of phenotypic subtypes; promotion of tumour proliferation, invasion and migration; induction of chemoresistance; promotion of angiogenesis; modulation of immunosuppression; reprogramming of metabolism; and interaction with the microbial community are summarised. Although the role of TAMs in GC remains controversial in clinical settings, clarifying their significance in the treatment selection and prognostic prediction of GC could support optimising TAM-centred clinicaltherapy.

CONCLUSION

In summary, we reviewed the the phenotypic polarisation, function and molecular mechanism of TAMs and their potential applications in the treatment selection and prognostic prediction of GC.