Interleukin-33 in Malignancies: Friends or Foes?

Predictive value of low serum interleukin-33 levels in acute ischemic stroke outcomes

Background

Human interleukin-33 (IL-33), a member of the IL-1 family, has been identified as a therapeutic target due to its role as a proinflammatory mediator in various diseases. This study aims to evaluate the prognostic value of serum IL-33 levels in patients admitted with their first-ever acute ischemic stroke.

Methods

This single-center, prospective, observational study included 216 patients with acute ischemic stroke. Serum IL-33 levels were measured at hospital admission to assess their predictive value for functional outcomes and mortality within 3 months. IL-33 levels were dichotomized at the median into two groups: the reduced group (IL-33 ≤ median) and the normal group (IL-33 > median).

Results

The median age of the 216 patients was 66 years (interquartile range [IQR], 56-75), with 132 (61.6%) being women. IL-33 serum levels were inversely correlated with stroke severity, as measured by the National Institutes of Health Stroke Scale (NIHSS) score and lesion size. Patients in the reduced IL-33 group had a higher rate of unfavorable outcomes (55.6% vs. 18.5%; absolute difference, 29.2% [95% confidence interval (CI), 24.5% to 34.4%]; odds ratio (OR), 3.19 [95% CI, 1.72 to 5.91]) and mortality (24.1% vs. 3.7%; absolute difference, 15.8% [95% CI, 13.1% to 18.3%]; OR, 4.12 [95% CI, 1.38 to 12.31]) compared to the normal group. Furthermore, IL-33 levels enhanced the prognostic accuracy of the NIHSS for predicting functional outcomes (combined area under the curve [AUC], 0.84; 95% CI, 0.79-0.84; P < 0.001) and mortality (combined AUC, 0.88; 95% CI, 0.83-0.94; P < 0.001).

Conclusion

This study demonstrates that lower IL-33 levels are associated with increased stroke severity and poorer prognosis. These findings suggest that IL-33 may serve as a valuable biomarker for predicting poor outcomes following acute ischemic stroke.

Targeting IL-33 reprograms the tumor microenvironment and potentiates antitumor response to anti-PD-L1 immunotherapy

BACKGROUND

The main challenge against patients with cancer to derive benefits from immune checkpoint inhibitors targeting PD-1/PD-L1 appears to be the immunosuppressive tumor microenvironment (TME), in which IL-33/ST2 signal fulfills critical functions. However, whether IL-33 limits the therapeutic efficacy of anti-PD-L1 remains uncertain.

METHODS

Molecular mechanisms of IL-33/ST2 signal on anti-PD-L1 treatment lewis lung carcinoma tumor model were assessed by RNA-seq, ELISA, WB and immunofluorescence (IF). A sST2-Fc fusion protein was constructed for targeting IL-33 and combined with anti-PD-L1 antibody for immunotherapy in colon and lung tumor models. On this basis, bifunctional fusion proteins were generated for PD-L1-targeted blocking of IL-33 in tumors. The underlying mechanisms of dual targeting of IL-33 and PD-L1 revealed by RNA-seq, scRNA-seq, FACS, IF and WB.

RESULTS

After anti-PD-L1 administration, tumor-infiltrating ST2+ regulatory T cells (Tregs) were elevated. Blocking IL-33/ST2 signal with sST2-Fc fusion protein potentiated antitumor efficacy of PD-L1 antibody by enhancing T cell responses in tumor models. Bifunctional fusion protein anti-PD-L1-sST2 exhibited enhanced antitumor efficacy compared with combination therapy, not only inhibited tumor progression and extended the survival, but also provided long-term protective antitumor immunity. Mechanistically, the superior antitumor activity of targeting IL-33 and PD-L1 originated from reducing immunosuppressive factors, such as Tregs and exhausted CD8+ T cells while increasing tumor-infiltrating cytotoxic T lymphocyte cells.

CONCLUSIONS

In this study, we demonstrated that IL-33/ST2 was involved in the immunosuppression mechanism of PD-L1 antibody therapy, and blockade by sST2-Fc or anti-PD-L1-sST2 could remodel the inflammatory TME and induce potent antitumor effect, highlighting the potential therapeutic strategies for the tumor treatment by simultaneously targeting IL-33 and PD-L1.

The potential role of CD8+ cytotoxic T lymphocytes and one branch connected with tissue-resident memory in non-luminal breast cancer

Advances in understanding the pathological mechanisms of breast cancer have resulted in the emergence of novel therapeutic strategies. However, triple-negative breast cancer (TNBC), a molecular subtype of breast cancer with a poor prognosis, lacks classical and general therapeutic targets, hindering the clinical application of several therapies to breast cancer. As insights into the unique immunity and molecular mechanisms of TNBC have become more extensive, immunotherapy has gradually become a valuable complementary approach to classical radiotherapy and chemotherapy. CD8+ cells are significant actors in the tumor immunity cycle; thus, research on TNBC immunotherapy is increasingly focused in this direction. Recently, CD8+ tissue-resident memory (TRM) cells, a subpopulation of CD8+ cells, have been explored in relation to breast cancer and found to seemingly play an undeniably important role in tumor surveillance and lymphocytic infiltration. In this review, we summarize the recent advances in the mechanisms and relative targets of CD8+ T cells, and discuss the features and potential applications of CD8+ TRM cells in non-luminal breast cancer immunotherapy.

Interleukin 33 supports squamous cell carcinoma growth via a dual effect on tumour proliferation, migration and invasion, and T cell activation

Interleukin (IL)-33 is an important cytokine in the tumour microenvironment; it is known to promote the growth and metastasis of solid cancers, such as gastric, colorectal, ovarian and breast cancer. Our group demonstrated that the IL-33/ST2 pathway enhances the development of squamous cell carcinoma (SCC). Conversely, other researchers have reported that IL-33 inhibits tumour progression. In addition, the crosstalk between IL-33, cancer cells and immune cells in SCC remains unknown. The aim of this study was to investigate the effect of IL-33 on the biology of head and neck SCC lines and to evaluate the impact of IL-33 neutralisation on the T cell response in a preclinical model of SCC. First, we identified epithelial and peritumoural cells as a major local source of IL-33 in human SCC samples. Next, in vitro experiments demonstrated that the addition of IL-33 significantly increased the proliferative index, motility and invasiveness of SCC-25 cells, and downregulated MYC gene expression in SCC cell lines. Finally, IL-33 blockade significantly delayed SCC growth and led to a marked decrease in the severity of skin lesions. Importantly, anti-IL-33 monoclonal antibody therapy increase the percentage of CD4+IFNγ+ T cells and decreased CD4+ and CD8+ T cells secreting IL-4 in tumour-draining lymph nodes. Together, these data suggest that the IL-33/ST2 pathway may be involved in the crosstalk between the tumour and immune cells by modulating the phenotype of head and neck SCC and T cell activity. IL-33 neutralisation may offer a novel therapeutic strategy for SCC.

Macrophages reprogramming improves immunotherapy of IL-33 in peritoneal metastasis of gastric cancer

Peritoneal metastasis (PM) has a suppressive tumor immune microenvironment (TIME) that limits the effects of immunotherapy. This study aimed to investigate the immunomodulatory effects of intraperitoneal administration of IL-33, a cytokine that is reported to potentiate antitumor immunity and inhibit metastasis. We found survival was significantly prolonged in patients with high IL-33 mRNA expression. In immunocompetent mice, intraperitoneal administration of IL-33 could induce a celiac inflammatory environment, activate immunologic effector cells, and reverse the immunosuppressive tumor microenvironment, which effectively delayed tumor progression and PM of gastric cancer. Mechanistically, IL-33 could induce M2 polarization by activating p38-GATA-binding protein 3 signaling. IL-33 combined with anti-CSF1R or p38 inhibitor to regulate tumor-associated macrophages (TAMs) had a synergistic antitumor effect. Inducing a local inflammatory milieu by IL-33 administration provided a novel approach for treating peritoneal metastasis, which, when combined with TAM reprogramming to reshape TIME, can achieve better treatment efficacy.

Interleukin-33 Expression on Treatment Outcomes and Prognosis in Brazilian Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

Interleukin-33 (IL-33), a member of the interleukin-1(IL-1) family of cytokines, remains poorly understood in the context of human breast cancer and its impact on treatment outcomes. This study aimed to elucidate IL-33 expression patterns within tumor samples from a cohort of Brazilian female breast cancer patients undergoing neoadjuvant chemotherapy while exploring its correlation with clinicopathological markers. In total, 68 samples were meticulously evaluated, with IL-33 expression quantified through a quantitative polymerase chain reaction. The findings revealed a substantial upregulation of IL-33 expression in breast cancer patient samples, specifically within the Triple-negative and Luminal A and B subtypes, when compared to controls (healthy breast tissues). Notably, the Luminal B subtype displayed a marked elevation in IL-33 expression relative to the Luminal A subtype (p < 0.05). Moreover, a progressive surge in IL-33 expression was discerned among Luminal subtype patients with TNM 4 staging criteria, further underscoring its significance (p < 0.005). Furthermore, chemotherapy-naïve patients of Luminal A and B subtypes exhibited heightened IL-33 expression (p < 0.05). Collectively, our findings propose that chemotherapy could potentially mitigate tumor aggressiveness by suppressing IL-33 expression in breast cancer, thus warranting consideration as a prognostic marker for gauging chemotherapy response and predicting disease progression in Luminal subtype patients. This study not only sheds light on the intricate roles of IL-33 in breast cancer but also offers valuable insights for future IL-33-related research endeavors within this context.

Biological effects of IL-33/ST2 axis on oral diseases: autoimmune diseases and periodontal diseases

IL-33 is a relatively new member of the IL-1 cytokine family, which plays a unique role in autoimmune diseases, particularly some oral diseases dominated by immune factors. The IL-33/ST2 axis is the main pathway by which IL-33 signals affect downstream cells to produce an inflammatory response or tissue repair. As a newly discovered pro-inflammatory cytokine, IL-33 can participate in the pathogenesis of autoimmune oral diseases such as Sjogren's syndrome and Behcet's disease. Moreover, the IL-33/ST2 axis also recruits and activates mast cells in periodontitis, producing inflammatory chemokines and mediating gingival inflammation and alveolar bone destruction. Interestingly, the high expression of IL-33 in the alveolar bone, which exhibits anti-osteoclast effects under appropriate mechanical loading, also confirms its dual role of destruction and repair in an immune-mediated periodontal environment. This study reviewed the biological effects of IL-33 in autoimmune oral diseases, periodontitis and periodontal bone metabolism, and elaborated its potential role and impact as a disease enhancer or a repair factor.

A Deep View of the Biological Property of Interleukin-33 and Its Dysfunction in the Gut

Intestinal diseases have always posed a serious threat to human health, with inflammatory bowel disease (IBD) being one of them. IBD is an autoimmune disease characterized by chronic inflammation, including ulcerative colitis (UC) and Crohn's disease (CD). The "alarm" cytokine IL-33, which is intimately associated with Th2 immunity, is a highly potent inflammatory factor that is considered to have dual functions-operating as both a pro-inflammatory cytokine and a transcriptional regulator. IL-33 has been shown to play a crucial role in both the onset and development of IBD. Therefore, this review focuses on the pathogenesis of IBD, the major receptor cell types, and the activities of IL-33 in innate and adaptive immunity, as well as its underlying mechanisms and conflicting conclusions in IBD. We have also summarized different medicines targeted to IL-33-associated diseases. Furthermore, we have emphasized the role of IL-33 in gastrointestinal cancer and parasitic infections, giving novel prospective therapeutic utility in the future application of IL-33.

Interactions between microglia and glioma in tumor microenvironment

Gliomas, the most prevalent primary tumors in the central nervous system, are marked by their immunosuppressive properties and consequent poor patient prognosis. Current evidence emphasizes the pivotal role of the tumor microenvironment in the progression of gliomas, largely attributed to tumor-associated macrophages (brain-resident microglia and bone marrow-derived macrophages) that create a tumor microenvironment conducive to the growth and invasion of tumor cells. Yet, distinguishing between these two cell subgroups remains a challenge. Thus, our review starts by analyzing the heterogeneity between these two cell subsets, then places emphasis on elucidating the complex interactions between microglia and glioma cells. Finally, we conclude with a summary of current attempts at immunotherapy that target microglia. However, given that independent research on microglia is still in its initial stages and has many shortcomings at the present time, we express our related concerns and hope that further research will be carried out to address these issues in the future.

In vitro cross-talk between metastasis-competent circulating tumor cells and platelets in colon cancer: a malicious association during the harsh journey in the blood

Background: Platelets are active players in hemostasis, coagulation and also tumorigenesis. The cross-talk between platelets and circulating tumor cells (CTCs) may have various pro-cancer effects, including promoting tumor growth, epithelial-mesenchymal transition (EMT), metastatic cell survival, adhesion, arrest and also pre-metastatic niche and metastasis formation. Interaction with CTCs might alter the platelet transcriptome. However, as CTCs are rare events, the cross-talk between CTCs and platelets is poorly understood. Here, we used our established colon CTC lines to investigate the colon CTC-platelet cross-talk in vitro and its impact on the behavior/phenotype of both cell types. Methods: We exposed platelets isolated from healthy donors to thrombin (positive control) or to conditioned medium from three CTC lines from one patient with colon cancer and then we monitored the morphological and protein expression changes by microscopy and flow cytometry. We then analyzed the transcriptome by RNA-sequencing of platelets indirectly (presence of a Transwell insert) co-cultured with the three CTC lines. We also quantified by reverse transcription-quantitative PCR the expression of genes related to EMT and cancer development in CTCs after direct co-culture (no Transwell insert) with platelets. Results: We observed morphological and transcriptomic changes in platelets upon exposure to CTC conditioned medium and indirect co-culture (secretome). Moreover, the expression levels of genes involved in EMT (p < 0.05) were decreased in CTCs co-cultured with platelets, but not of genes encoding mesenchymal markers (FN1 and SNAI2). The expression levels of genes involved in cancer invasiveness (MYC, VEGFB, IL33, PTGS2, and PTGER2) were increased. Conclusion: For the first time, we studied the CTC-platelet cross-talk using our unique colon CTC lines. Incubation with CTC conditioned medium led to platelet aggregation and activation, supporting the hypothesis that their interaction may contribute to preserve CTC integrity during their journey in the bloodstream. Moreover, co-culture with platelets influenced the expression of several genes involved in invasiveness and EMT maintenance in CTCs.

Identification of novel candidate targets for suppressing ovarian cancer progression through IL-33/ST2 axis components using the system biology approach

Background: Cancer-associated fibroblasts (CAFs) of ovarian cancer (OvC) are the most prevalent element of the tumor microenvironment (TM). By promoting angiogenesis, immunological suppression, and invasion, CAFs speed up the growth of tumors by changing the extracellular matrix's structure and composition and/or initiating the epithelial cells (EPT). IL-33/ST2 signaling has drawn a lot of attention since it acts as a pro-tumor alarmin and encourages spread by altering TM. Methods: Differentially expressed genes (DEGs) of the OvC tumor microenvironment were found in the GEO database, qRT-PCR, western blotting, and immunohistochemistry, and their presence and changes in healthy and tumor tissue content were examined. Primary cultures of healthy fibroblasts and CAFs obtained from healthy and tumor tissues retrieved from OvC samples were used for in vitro and in vivo investigations. Cultured primary human CAFs were utilized to investigate the regulation and the IL-33/ST2 axis role in the inflammation reactions. Results: Although ST2 and IL-33 expression was detected in both epithelial (EPT) and fibroblast cells of ovarian cancer, they are more abundant in CAFs. Lipopolysaccharides, serum amyloid A1, and IL-1β, the inflammatory mediators, could all induce IL-33 expression through NF-κB activation in human CAFs. In turn, via the ST2 receptor, IL-33 affected the production of IL-6, IL-1β, and PTGS2 in human CAFs via the MAPKs-NF-κB pathway. Conclusion: Our findings suggest that IL-33/ST2 is affected by the interaction of CAFs and epithelial cells inside the tumor microenvironment. Activation of this axis leads to increased expression of inflammatory factors in tumor CAFs and EPT cells. Therefore, targeting the IL-33/ST2 axis could have potential value in the prevention of OvC progression.

Comparison of Interleukin-33 Serum Levels in Patients with Breast Cancer and Idiopathic Granulomatous Mastitis

BACKGROUND

Breast cancer (BC) is the main cause of cancer death in women. Idiopathic granulomatous mastitis (IGM), a rare chronic disease that clinically mimics breast carcinoma, and is associated with high mortality and morbidity, but an immediate and accurate diagnosis can substantially decrease these rates. Expressed by numerous human tissues, interleukin-33 (IL-33) has an inductive role in the network of pro-inflammatory cytokines. The aim of this study was to investigate the serum levels of IL-33 in BC and IGM patients in comparison with healthy women.

MATERIALS AND METHODS

This descriptive-analytical study was carried out on 28 patients with BC and 25 patients with IGM as the patient groups and 25 healthy volunteers with normal screening reports as the control group. Histopathological pattern of BC and IGM were confirmed by specialized pathologists. The serum concentration of IL-33 was measured using enzyme-linked immunosorbent assay (ELISA) kit according to the manufacturer's instructions.

RESULTS

The mean age of the patients with BC and IGM and the control group was 49.1, 37.1, and 36.8 years, respectively. There was no significant difference in IL-33 expression among the participants with regard to age, marital status, body mass index (BMI), and menopausal status. IL-33 assay indicated a significant difference between the BC (P=0.011) and IGM (P=0.031) groups compared to the controls, although no substantial differences were observed between the IGM and BC groups.

CONCLUSION

IL-33 can be considered a significant factor distinguishing IGM and BC patients from controls, although it cannot be applied to diagnose and differentiate BC from IGM patients.
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Modulation of T-cell function by myeloid-derived suppressor cells in hematological malignancies

Myeloid-derived suppressor cells (MDSCs) are pathologically activated neutrophils and monocytes that negatively regulate the immune response to cancer and chronic infections. Abnormal myelopoiesis and pathological activation of myeloid cells generate this heterogeneous population of myeloid-derived suppressor cells. They are characterized by their distinct transcription, phenotypic, biochemical, and functional features. In the tumor microenvironment (TME), myeloid-derived suppressor cells represent an important class of immunosuppressive cells that correlate with tumor burden, stage, and a poor prognosis. Myeloid-derived suppressor cells exert a strong immunosuppressive effect on T-cells (and a broad range of other immune cells), by blocking lymphocyte homing, increasing production of reactive oxygen and nitrogen species, promoting secretion of various cytokines, chemokines, and immune regulatory molecules, stimulation of other immunosuppressive cells, depletion of various metabolites, and upregulation of immune checkpoint molecules. Additionally, the heterogeneity of myeloid-derived suppressor cells in cancer makes their identification challenging. Overall, they serve as a major obstacle for many cancer immunotherapies and targeting them could be a favorable strategy to improve the effectiveness of immunotherapeutic interventions. However, in hematological malignancies, particularly B-cell malignancies, the clinical outcomes of targeting these myeloid-derived suppressor cells is a field that is still to be explored. This review summarizes the complex biology of myeloid-derived suppressor cells with an emphasis on the immunosuppressive pathways used by myeloid-derived suppressor cells to modulate T-cell function in hematological malignancies. In addition, we describe the challenges, therapeutic strategies, and clinical relevance of targeting myeloid-derived suppressor cells in these diseases.

IL-5-producing CD4+ T cells and eosinophils cooperate to enhance response to immune checkpoint blockade in breast cancer

Immune checkpoint blockade (ICB) has heralded a new era in cancer therapy. Research into the mechanisms underlying response to ICB has predominantly focused on T cells; however, effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. Here, we combine unbiased analysis of blood and tumors from metastatic breast cancer patients treated with ICB with mechanistic studies in mouse models of breast cancer. We observe an increase in systemic and intratumoral eosinophils in patients and mice responding to ICB treatment. Mechanistically, ICB increased IL-5 production by CD4⁺ T cells, stimulating elevated eosinophil production from the bone marrow, leading to systemic eosinophil expansion. Additional induction of IL-33 by ICB-cisplatin combination or recombinant IL-33 promotes intratumoral eosinophil infiltration and eosinophil-dependent CD8⁺ T cell activation to enhance ICB response. This work demonstrates the critical role of eosinophils in ICB response and provides proof-of-principle for eosinophil engagement to enhance ICB efficacy.

Knowledge mapping of interleukin-33: a bibliometric study

Interleukin-33 (IL-33) is a member of the IL-1 family of cytokines. IL-33 is associated with the expression of tissue damage or necrosis after increasing and being released into the cell, it influences the suppression of tumorigenicity 2 (ST2) receptor expression of a variety of immune cells (including mast cells and type 2 congenital lymphocytes). Furthermore, during type 2 innate immune reactions and allergic inflammation IL-33 plays a central role in immune amplification and "alarming"; thus, regulating immune responeses. IL-33 is closely related to inflammation-related diseases such as allergic diseases, autoimmune diseases, infectious diseases, and tumors. It is essential in maintaining tissue homeostasis, eliminating inflammation, and repairing tissue damage. We searched the Web of Science Core Collection (WoSCC) database for relevant publications on IL-33 from 2005 to 2021 and screened them according to specific inclusion criteria. A total of 2626 articles were included in our analysis. Using Microsoft Excel 2019 (Redmond, WA), VOSviewer 1.6.11 (The Centre for Science and Technology Studies, CWTS), and Citespace5.8. R2 (Drexel University, Philadelphia, PA) were used for data processing and visualization. Countries/regions, journals, authors, co-cited references, and keywords were analyzed. We discovered that IL-33 plays an important role as a cytokine in numerous diseases, especially allergic diseases. Studying its mechanism of action is of great importance for developing novel drugs and therapeutics.

Microglia and Brain Macrophages as Drivers of Glioma Progression

Evidence is accumulating that the tumour microenvironment (TME) has a key role in the progression of gliomas. Non-neoplastic cells in addition to the tumour cells are therefore finding increasing attention. Microglia and other glioma-associated macrophages are at the centre of this interest especially in the context of therapeutic considerations. New ideas have emerged regarding the role of microglia and, more recently, blood-derived brain macrophages in glioblastoma (GBM) progression. We are now beginning to understand the mechanisms that allow malignant glioma cells to weaken microglia and brain macrophage defence mechanisms. Surface molecules and cytokines have a prominent role in microglia/macrophage-glioma cell interactions, and we discuss them in detail. The involvement of exosomes and microRNAs forms another focus of this review. In addition, certain microglia and glioma cell pathways deserve special attention. These "synergistic" (we suggest calling them "Janus") pathways are active in both glioma cells and microglia/macrophages where they act in concert supporting malignant glioma progression. Examples include CCN4 (WISP1)/Integrin α6β1/Akt and CHI3L1/PI3K/Akt/mTOR. They represent attractive therapeutic targets.

The role of IL-33/ST2 signaling in the tumor microenvironment and Treg immunotherapy

Interleukin (IL)-33 is a tissue-derived nuclear cytokine belonging to the IL-1 family. Stimulation-2 (ST2) is the only known IL-33 receptor. ST2 signals mostly on immune cells found within tissues, such as regulatory T cells (Treg cells), CD8+ T cells, and natural killer (NK) cells. Therefore, the IL-33/ST2 signaling pathway is important in the immune system. IL-33 deficiency impairs Treg cell function. ST2 signaling is also increased in active Treg cells, providing a new approach for Treg-related immunotherapy. The IL-33/ST2 signaling pathway regulates multiple immune-related cells by activating various intracellular kinases and factors in the tumor microenvironment (TME). Here, we review the latest studies on the role of the IL-33/ST2 signaling pathway in TME and Treg immunotherapy.

Role of Interleukin-1 family in bone metastasis of prostate cancer

Prostate cancer (PCa) is one of the most fatal diseases in male patients with high bone metastatic potential. Bone metastasis severely shortens overall survival and brings skeletal-related events (SREs) which reduces the life quality of patients, and this situation is currently regarded as irreversible and incurable. The progression and metastasis of PCa are found to be closely associated with inflammatory cytokines and chemokines. As pivotal members of inflammatory cytokines, Interleukin-1 (IL-1) family plays a crucial role in this process. Elevated expression of IL-1 family was detected in PCa patients with bone metastasis, and accumulating evidences proved that IL-1 family could exert vital effects on the progression and bone metastasis of many cancers, while some members have dual effects. In this review, we discuss the role of IL-1 family in the bone metastasis of PCa. Furthermore, we demonstrate that many members of IL-1 family could act as pivotal biomarkers to predict the clinical stage and prognosis of PCa patients. More importantly, we have elucidated the role of IL-1 family in the bone metastasis of PCa, which could provide potential targets for the treatment of PCa bone metastasis and probable directions for future research.

Targeting of MCL-1 in breast cancer-associated fibroblasts reverses their myofibroblastic phenotype and pro-invasive properties

Cancer-associated fibroblasts (CAF) are a major cellular component of epithelial tumors. In breast cancers in particular these stromal cells have numerous tumorigenic effects in part due to their acquisition of a myofibroblastic phenotype. Breast CAFs (bCAFs) typically express MCL-1. We show here that pharmacological inhibition or knock down of this regulator of mitochondrial integrity in primary bCAFs directly derived from human samples mitigates myofibroblastic features. This decreases expression of genes involved in actomyosin organization and contractility (associated with a cytoplasmic retention of the transcriptional regulator, yes-associated protein-YAP) and decreases bCAFs ability to promote cancer cells invasion in 3D coculture assays. Our findings underscore the usefulness of targeting MCL-1 in breast cancer ecosystems, not only to favor death of cancer cells but also to counteract the tumorigenic activation of fibroblasts with which they co-evolve. Mechanistically, pharmacological inhibition of MCL-1 with a specific BH3 mimetic promotes mitochondrial fragmentation in bCAFs. Inhibition of the mitochondrial fission activity of DRP-1, which interacts with MCL-1 upon BH3 mimetic treatment, allows the maintenance of the myofibroblastic phenotype of bCAFs.

IL-33 biology in cancer: An update and future perspectives

Interleukin-33 (IL-33) is a member of the IL-1 family of cytokines that is constitutively expressed in the nucleus of epithelial, endothelial and fibroblast-like cells. Upon cell stress, damage or necrosis, IL-33 is released into the cytoplasm to exert its prime role as an alarmin by binding to its specific receptor moiety, ST2. IL-33 exhibits pleiotropic function in inflammatory diseases and particularly in cancer. IL-33 may play a dual role as both a pro-tumorigenic and anti-tumorigenic cytokine, dependent on tumor and cellular context, expression levels, bioactivity and the nature of the inflammatory environment. In this review, we discuss the differential contribution of IL-33 to malignant or inflammatory conditions, its multifaceted effects on the tumor microenvironment, while providing possible explanations for the discrepant findings described in the literature. Additionally, we examine the emerging and divergent functions of IL-33 in the nucleus, and aspects of IL-33 biology that are currently under-addressed.

Diversification of circulating and tumor-infiltrating plasmacytoid DCs towards the P3 (CD80+ PDL1-)-pDC subset negatively correlated with clinical outcomes in melanoma patients

Objectives

Plasmacytoid DCs (pDCs) play a critical yet enigmatic role in antitumor immunity through their pleiotropic immunomodulatory functions. Despite proof of pDC diversity in several physiological or pathological contexts, pDCs have been studied as a whole population so far in cancer. The assessment of individual pDC subsets is needed to fully grasp their involvement in cancer immunity, especially in melanoma where pDC subsets are largely unknown and remain to be uncovered.

Methods

We explored for the first time the features of diverse circulating and tumor-infiltrating pDC subsets in melanoma patients using multi-parametric flow cytometry, and assessed their clinical relevance. Based on CD80, PDL1, CD2, LAG3 and Axl markers, we provided an integrated overview of the frequency, basal activation status and functional features of pDC subsets in melanoma patients together with their relationship to clinical outcome.

Results

Strikingly, we demonstrated that P3-pDCs (CD80⁺PDL1^-) accumulated within the tumor of melanoma patients and negatively correlated with clinical outcomes. The basal activation status, diversification towards P1-/P2-/P3-pDCs and functionality of several pDC subsets upon TLR7/TLR9 triggering were perturbed in melanoma patients, and were differentially linked to clinical outcome.

Conclusion

Our study shed light for the first time on the phenotypic and functional heterogeneity of pDCs in the blood and tumor of melanoma patients and their potential involvement in shaping clinical outcomes. Such novelty brightens our understanding of pDC complexity, and prompts the further deciphering of pDCs' features to better apprehend and exploit these potent immune players. It highlights the importance of considering pDC diversity when developing pDC-based therapeutic strategies to ensure optimal clinical success.

The Merkel Cell Polyomavirus T-Antigens and IL-33/ST2-IL1RAcP Axis: Possible Role in Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) is a causal factor in Merkel cell carcinoma (MCC). The oncogenic potential is mediated through its viral oncoproteins large T-antigen (LT) and small T-antigen (sT). Cytokines produced by tumor cells play an important role in cancer pathogenesis, and viruses affect their expression. Therefore, we compared human cytokine and receptor transcript levels in virus positive (V+) and virus negative (V−) MCC cell lines. Increased expression of IL-33, a potent modulator of tumor microenvironment, was observed in V+ MCC cell lines when compared to V− MCC-13 cells. Transient transfection studies with luciferase reporter plasmids demonstrated that LT and sT stimulated IL-33, ST2/IL1RL1 and IL1RAcP promoter activity. The induction of IL-33 expression was confirmed by transfecting MCC-13 cells with MCPyV LT. Furthermore, recombinant human cytokine domain IL-33 induced activation of MAP kinase and NF-κB pathways, which could be blocked by a ST2 receptor antibody. Immunohistochemical analysis demonstrated a significantly stronger IL-33, ST2, and IL1RAcP expression in MCC tissues compared to normal skin. Of interest, significantly higher IL-33 and IL1RAcP protein levels were observed in MCC patient plasma compared to plasma from healthy controls. Previous studies have demonstrated the implication of the IL-33/STL2 pathway in cancer. Because our results revealed a T-antigens-dependent induction of the IL-33/ST2 axis, IL-33/ST2 may play a role in the tumorigenesis of MCPyV-positive MCC. Therefore, neutralizing the IL-33/ST2 axis may present a novel therapeutic approach for MCC patients.

Interleukin-33/ Suppression of Tumorigenicity 2 in Renal Fibrosis: Emerging Roles in Prognosis and Treatment

Chronic kidney disease (CKD) is a major public health problem that affects more than 10% of the population worldwide and has a high mortality rate. Therefore, it is necessary to identify novel treatment strategies for CKD. Incidentally, renal fibrosis plays a central role in the progression of CKD to end-stage renal disease (ESRD). The activation of inflammatory pathways leads to the development of renal fibrosis. In fact, interleukin-33 (IL-33), a newly discovered member of the interleukin 1 (IL-1) cytokine family, is a crucial regulator of the inflammatory process. It exerts pro-inflammatory and pro-fibrotic effects via the suppression of tumorigenicity 2 (ST2) receptor, which, in turn, activates other inflammatory pathways. Although the role of this pathway in cardiac, pulmonary, and hepatic fibrotic diseases has been extensively studied, its precise role in renal fibrosis has not yet been completely elucidated. Recent studies have shown that a sustained activation of IL-33/ST2 pathway promotes the development of renal fibrosis. However, with prolonged research in this field, it is expected that the IL-33/ST2 pathway will be used as a diagnostic and prognostic tool for renal diseases. In addition, the IL-33/ST2 pathway seems to be a new target for the future treatment of CKD. Here, we review the mechanisms and potential applications of the IL-33/ST2 pathway in renal fibrosis; such that it can help clinicians and researchers to explore effective treatment options and develop novel medicines for CKD patients.

IL-33 Promotes the Growth of Non-Small Cell Lung Cancer Cells Through Regulating miR-128-3p/CDIP1 Signalling Pathway

BACKGROUND

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related deaths, and it is also the most frequently diagnosed cancer. Previous studies indicate that IL-33 plays a crucial role in the development of NSCLC. In recent years, the role of miRNAs in cancer has become increasingly clear. However, reports focused on the relation between IL-33 and miRNAs in NSCLC have been limited.

METHODS

The expression of IL-33 and miR-128-3p was detected by qPCR. MTT, EdU, and colony formation assays were used to detect the proliferation ability of NSCLC cells. Transwell assay was used to investigate the migration and invasion of NSCLC cells. The expression of bax, cyt-c, and caspase 3 was detected by Western blot. Finally, in vivo tumor xenograft was used to detect the effects of IL-33 and miR-128-3p on tumor growth capacity.

RESULTS

IL-33 was notably increased in the serum and tumor tissue of NSCLC patients. The in vitro function study revealed that IL-33 significantly promotes the proliferation, migration, and invasion of the NSCLC cells. In vivo experiments further confirmed the pro-tumor effect of IL-33 on NSCLC. The study on the underlying mechanism elucidated that IL-33 regulates the expression of miR-128-3p, which can directly target and inhibit the expression of CDIP1. Furthermore, IL-33 regulates the expression of downstream apoptotic proteins such as bax, cyt-c, and caspase3. Rescue experiments demonstrated that miR-28-3p can reverse the effect of IL-33.

CONCLUSION

These findings indicated that IL-33 and miR-128-3p may play a potential role in the diagnosis and treatment of NSCLC.

The IL-33/ST2 axis affects tumor growth by regulating mitophagy in macrophages and reprogramming their polarization

Objective:

Macrophages are a major component of the tumor microenvironment. M1 macrophages secrete pro-inflammatory factors that inhibit tumor growth and development, whereas tumor-associated macrophages (TAMs) mainly exhibit an M2 phenotype. Our previous studies have shown that the interleukin-33/ST2 (IL-33/ST2) axis is essential for activation of the M1 phenotype. This study investigates the role of the IL-33/ST2 axis in TAMs, its effects on tumor growth, and whether it participates in the mutual conversion between the M1 and M2 phenotypes.

Methods:

Bone marrow-derived macrophages were extracted from wildtype, ST2 knockout (ST2^−/−), and Il33-overexpressing mice and differentiated with IL-4. The mitochondrial and lysosomal number and location, and the expression of related proteins were used to analyze mitophagy. Oxygen consumption rates and glucose and lactate levels were measured to reveal metabolic changes.

Results:

The IL-33/ST2 axis was demonstrated to play an important role in the metabolic conversion of macrophages from OXPHOS to glycolysis by altering mitophagy levels. The IL-33/ST2 axis promoted enhanced cell oxidative phosphorylation, thereby further increasing M2 polarization gene expression and ultimately promoting tumor growth (P < 0.05) (Figure 4). This metabolic shift was not due to mitochondrial damage, because the mitochondrial membrane potential was not significantly altered by IL-4 stimulation or ST2 knockout; however, it might be associated with the mTOR activity.

Conclusions:

These results clarify the interaction between the IL-33/ST2 pathway and macrophage polarization, and may pave the way to the development of new cancer immunotherapies targeting the IL-33/ST2 axis.

Interaction Between MDSC and NK Cells in Solid and Hematological Malignancies: Impact on HSCT

Myeloid derived suppressor cells (MDSC) are heterogeneous populations that through the release of soluble factors and/or by cell-to-cell interactions suppress both innate and adaptive immune effector cells. In pathological conditions, characterized by the presence of inflammation, a partial block in the differentiation potential of myeloid precursors causes an accumulation of these immunosuppressive cell subsets both in peripheral blood and in tissues. On the contrary, NK cells represent a major player of innate immunity able to counteract tumor growth. The anti-tumor activity of NK cells is primarily related to their cytolytic potential and to the secretion of soluble factors or cytokines that may act on tumors either directly or indirectly upon the recruitment of other cell types. NK cells have been shown to play a fundamental role in haploidentical hemopoietic stem cell transplantation (HSCT), for the therapy of high-risk leukemias. A deeper analysis of MDSC functional effects demonstrated that these cells are capable, through several mechanisms, to reduce the potent GvL activity exerted by NK cells. It is conceivable that, in this transplantation setting, the MDSC-removal or -inactivation may represent a promising strategy to restore the anti-leukemia effect mediated by NK cells. Thus, a better knowledge of the cellular interactions occurring in the tumor microenvironment could promote the development of novel therapeutic strategies for the treatment of solid and hematological malignances.

Safety and efficacy of extended dosing intervals of denosumab in patients with solid cancers and bone metastases: a retrospective study

Aim

More than half of patients with breast, lung, or prostate cancer who have bone metastases have evidence of skeletal-related events (SREs). Denosumab is a fully human monoclonal antibody that binds to and neutralizes receptor activator of nuclear factor kappa-B ligand (RANKL) on osteoblasts and their precursors. The United States Food and Drug Administration (FDA)-approved dose of denosumab is 120 mg every 4 weeks; however, other schedules have been used in practice for patient convenience. Evidence for the safety and efficacy of alternative dosing intervals is lacking.

Patient & Methods

Adult patients with solid cancers and bone metastases who received at least two doses of denosumab 120 mg were reviewed. Patients were grouped based on an average denosumab dosing interval of <5 weeks (short-interval) versus 5-11 weeks (medium-interval) versus ⩾12 weeks (long-interval). The primary outcome was the time to first SRE while on denosumab between the short- and medium-interval groups. The secondary outcomes were overall survival (OS), efficacy comparisons between the other groups, and safety events.

Results

There was no significant difference in median time to first SRE between the short- and medium-interval denosumab groups [33.2 versus 28.4 months, hazard ratio (HR): 1.13, 95% confidence interval (CI): 0.66-1.92, p = 0.91] or the medium- and long-interval dosing groups (28.4 versus 32.2 months, HR: 1.15, 95% CI: 0.66-2.01, p = 0.62). Median OS was not found to differ significantly between any of the groups. There were significantly more hospitalizations in the short-interval dosing group than the other groups (55.2% versus 33.8% versus 30.4%, p < 0.001).

Conclusion

Extending denosumab dosing intervals does not appear to negatively impact time to first SRE and is associated with fewer hospitalizations in real-world patients with solid cancers and bone metastases.

Interaction Between MDSC and NK Cells in Solid and Hematological Malignancies: Impact on HSCT

Myeloid derived suppressor cells (MDSC) are heterogeneous populations that through the release of soluble factors and/or by cell-to-cell interactions suppress both innate and adaptive immune effector cells. In pathological conditions, characterized by the presence of inflammation, a partial block in the differentiation potential of myeloid precursors causes an accumulation of these immunosuppressive cell subsets both in peripheral blood and in tissues. On the contrary, NK cells represent a major player of innate immunity able to counteract tumor growth. The anti-tumor activity of NK cells is primarily related to their cytolytic potential and to the secretion of soluble factors or cytokines that may act on tumors either directly or indirectly upon the recruitment of other cell types. NK cells have been shown to play a fundamental role in haploidentical hemopoietic stem cell transplantation (HSCT), for the therapy of high-risk leukemias. A deeper analysis of MDSC functional effects demonstrated that these cells are capable, through several mechanisms, to reduce the potent GvL activity exerted by NK cells. It is conceivable that, in this transplantation setting, the MDSC-removal or -inactivation may represent a promising strategy to restore the anti-leukemia effect mediated by NK cells. Thus, a better knowledge of the cellular interactions occurring in the tumor microenvironment could promote the development of novel therapeutic strategies for the treatment of solid and hematological malignances.

Exogenous interleukin-33 promotes hepatocellular carcinoma growth by remodelling the tumour microenvironment

Background

Interleukin-33 (IL-33) is an effective inducer of pro-inflammatory cytokines regulating innate and adaptive immunity. Inflammation could be a double-edged sword, promoting or inhibiting tumour growth. To date, the roles and mechanisms of IL-33 in tumours remain controversial. Here, we examined the effect of exogenous IL-33 on the biological characteristics of hepatocellular carcinoma (HCC) and the possible mechanism of action.

Methods

In this study, IL-33 expression in the tissues of 69 HCC patients was detected and its relationship with prognosis was evaluated. After establishing a mouse HCC model and IL-33 treatment operation, the infiltration of splenic myeloid-derived suppressor (MDSCs), dendritic (DCs), regulatory T, and natural killer (NK) cells was detected by flow cytometry analysis, and the vascular density of the tumour tissues was detected by immunohistochemistry to reveal the mechanism of IL-33 in HCC proliferation. Finally, the Cancer Genome Atlas database was used to analyse Gene Ontology terms the and Kyoto Encyclopaedia of Genes and Genomes pathway. Moreover, the chi-square test, two-tailed unpaired Student’s t-test, and multiple t-tests were performed using SPSS version 23.0 and GraphPad Prism 8.0 software.

Results

The IL-33 expression level was negatively correlated with the overall survival of HCC patients, suggesting its potential clinical significance in the prognosis of HCC. We found that systemic IL-33 administration significantly promoted the tumour size in vivo. Furthermore, the IL-33-treated mice presented decreased frequencies of tumouricidal NK and CD69⁺ CD8⁺ T cells. After IL-33 treatment, the incidence of monocytic MDSCs and conventional DCs increased, while that of granulocytic MDSCs decreased. Moreover, IL-33 promoted the formation of intracellular neovascularization. Therefore, IL-33 accelerated HCC progression by increasing the accumulation of immunosuppressive cells and neovascularization formation. Finally, we found that the transcription of IL-33 was closely related to the PI3K-Akt and MAPK pathways in Gene Set Enrichment Analysis plots, which were involved in the tumourigenesis and pathogenesis of HCC.

Conclusions

Taken together, IL-33 may be a key tumour promoter of HCC proliferation and tumourigenicity, an important mediator, and a potential therapeutic target for regulating HCC progression.

BDCA1+ cDC2s, BDCA2+ pDCs and BDCA3+ cDC1s reveal distinct pathophysiologic features and impact on clinical outcomes in melanoma patients

Objectives

Dendritic cells play a pivotal but still enigmatic role in the control of tumor development. Composed of specialised subsets (cDC1s, cDC2s, pDCs), DCs are critical in triggering and shaping antitumor immune responses. Yet, tumors exploit plasticity of DCs to subvert their functions and escape from immune control. This challenging controversy prompted us to explore the pathophysiological role of cDCs and pDCs in melanoma, where their precise and coordinated involvement remains to be deciphered.

Methods

We investigated in melanoma patients the phenotypic and functional features of circulating and tumor‐infiltrating BDCA1⁺ cDC2s, BDCA2⁺ pDCs and BDCA3⁺ cDC1s and assessed their clinical impact.

Results

Principal component analyses (PCA) based on phenotypic or functional parameters of DC subsets revealed intra‐group clustering, highlighting specific features of DCs in blood and tumor infiltrate of patients compared to healthy donors. DC subsets exhibited perturbed frequencies in the circulation and actively infiltrated the tumor site, while harbouring a higher activation status. Whereas cDC2s and pDCs displayed an altered functionality in response to TLR triggering, circulating and tumor‐infiltrating cDC1s preserved potent competences associated with improved prognosis. Notably, the proportion of circulating cDC1s predicted the clinical outcome of melanoma patients.

Conclusion

Such understanding uncovers critical and distinct impact of each DC subset on clinical outcomes and unveils fine‐tuning of interconnections between DCs in melanoma. Elucidating the mechanisms of DC subversion by tumors could help designing new therapeutic strategies exploiting the potentialities of these powerful immune players and their cross‐talks, while counteracting their skewing by tumors, to achieve immune control and clinical success.

Fibroblast-Derived IL33 Facilitates Breast Cancer Metastasis by Modifying the Immune Microenvironment and Driving Type 2 Immunity

Lungs are one of the main sites of breast cancer metastasis. The metastatic microenvironment is essential to facilitate growth of disseminated tumor cells. Cancer-associated fibroblasts (CAF) are prominent players in the microenvironment of breast cancer. However, their role in the formation of a permissive metastatic niche is unresolved. Here we show that IL33 is upregulated in metastases-associated fibroblasts in mouse models of spontaneous breast cancer metastasis and in patients with breast cancer with lung metastasis. Upregulation of IL33 instigated type 2 inflammation in the metastatic microenvironment and mediated recruitment of eosinophils, neutrophils, and inflammatory monocytes to lung metastases. Importantly, targeting of IL33 in vivo resulted in inhibition of lung metastasis and significant attenuation of immune cell recruitment and type 2 immunity. These findings demonstrate a key function of IL33 in facilitating lung metastatic relapse by modulating the immune microenvironment. Our study shows a novel interaction axis between CAF and immune cells and reveals the central role of CAF in establishing a hospitable inflammatory niche in lung metastasis. SIGNIFICANCE: This study elucidates a novel role for fibroblast-derived IL33 in facilitating breast cancer lung metastasis by modifying the immune microenvironment at the metastatic niche toward type 2 inflammation.

Glioma-derived IL-33 orchestrates an inflammatory brain tumor microenvironment that accelerates glioma progression

Despite a deeper molecular understanding, human glioblastoma remains one of the most treatment refractory and fatal cancers. It is known that the presence of macrophages and microglia impact glioblastoma tumorigenesis and prevent durable response. Herein we identify the dual function cytokine IL-33 as an orchestrator of the glioblastoma microenvironment that contributes to tumorigenesis. We find that IL-33 expression in a large subset of human glioma specimens and murine models correlates with increased tumor-associated macrophages/monocytes/microglia. In addition, nuclear and secreted functions of IL-33 regulate chemokines that collectively recruit and activate circulating and resident innate immune cells creating a pro-tumorigenic environment. Conversely, loss of nuclear IL-33 cripples recruitment, dramatically suppresses glioma growth, and increases survival. Our data supports the paradigm that recruitment and activation of immune cells, when instructed appropriately, offer a therapeutic strategy that switches the focus from the cancer cell alone to one that includes the normal host environment.

Immune-Stromal Score Signature: Novel Prognostic Tool of the Tumor Microenvironment in Lung Adenocarcinoma

Background: Immune and stromal cells in the tumor microenvironment (TME) significantly contribute to the prognosis of lung adenocarcinoma; however, the TME-related immune prognostic signature is unknown. The aim of this study was to develop a novel immune prognostic model of the TME in lung adenocarcinoma. Methods: First, the immune and stromal scores among lung adenocarcinoma patients were determined using the ESTIMATE algorithm in accordance with The Cancer Genome Atlas (TCGA) database. Differentially expressed immune-related genes (IRGs) between high and low immune/stromal score groups were analyzed, and a univariate Cox regression analysis was performed to identify IRGs significantly correlated with overall survival (OS) among patients with lung adenocarcinoma. Furthermore, a least absolute shrinkage and selection operator (LASSO) regression analysis was performed to generate TME-related immune prognostic signatures. Gene set enrichment analysis was performed to analyze the mechanisms underlying these immune prognostic signatures. Finally, the functions of hub IRGs were further analyzed to delineate the potential prognostic mechanisms in comprehensive TCGA datasets. Results: In total, 702 intersecting differentially expressed IRGs (589 upregulated and 113 downregulated) were screened. Univariate Cox regression analysis revealed that 58 significant differentially expressed IRGs were correlated with patient prognosis in the training cohort, of which three IRGs (CLEC17A, INHA, and XIRP1) were identified through LASSO regression analysis. A robust prognostic model was generated on the basis of this three-IRG signature. Furthermore, functional enrichment analysis of the high-risk-score group was performed primarily on the basis of metabolic pathways, whereas analysis of the low-risk-score group was performed primarily on the basis of immunoregulation and immune cell activation. Finally, hub IRGs CLEC17A, INHA, and XIRP1 were considered novel prognostic biomarkers for lung adenocarcinoma. These hub genes had different mutation frequencies and forms in lung adenocarcinoma and participated in different signaling pathways. More importantly, these hub genes were significantly correlated with the infiltration of CD4+ T cells, CD8+ T cells, macrophages, B cells, and neutrophils. Conclusions: The robust novel TME-related immune prognostic signature effectively predicted the prognosis of patients with lung adenocarcinoma. Further studies are required to further elucidate the regulatory mechanisms of these hub IRGs in the TME and to develop new treatment strategies.

The soluble glycoprotein NMB (GPNMB) produced by macrophages induces cancer stemness and metastasis via CD44 and IL-33

In cancer, myeloid cells have tumor-supporting roles. We reported that the protein GPNMB (glycoprotein nonmetastatic B) was profoundly upregulated in macrophages interacting with tumor cells. Here, using mouse tumor models, we show that macrophage-derived soluble GPNMB increases tumor growth and metastasis in Gpnmb-mutant mice (DBA/2J). GPNMB triggers in the cancer cells the formation of self-renewing spheroids, which are characterized by the expression of cancer stem cell markers, prolonged cell survival and increased tumor-forming ability. Through the CD44 receptor, GPNMB mechanistically activates tumor cells to express the cytokine IL-33 and its receptor IL-1R1L. We also determined that recombinant IL-33 binding to IL-1R1L is sufficient to induce tumor spheroid formation with features of cancer stem cells. Overall, our results reveal a new paracrine axis, GPNMB and IL-33, which is activated during the cross talk of macrophages with tumor cells and eventually promotes cancer cell survival, the expansion of cancer stem cells and the acquisition of a metastatic phenotype.

Single-Cell Transcriptomic Analysis of Tumor-Derived Fibroblasts and Normal Tissue-Resident Fibroblasts Reveals Fibroblast Heterogeneity in Breast Cancer

Cancer-associated fibroblasts (CAFs) are a prominent stromal cell type in solid tumors and molecules secreted by CAFs play an important role in tumor progression and metastasis. CAFs coexist as heterogeneous populations with potentially different biological functions. Although CAFs are a major component of the breast cancer stroma, molecular and phenotypic heterogeneity of CAFs in breast cancer is poorly understood. In this study, we investigated CAF heterogeneity in triple-negative breast cancer (TNBC) using a syngeneic mouse model, BALB/c-derived 4T1 mammary tumors. Using single-cell RNA sequencing (scRNA-seq), we identified six CAF subpopulations in 4T1 tumors including: 1) myofibroblastic CAFs, enriched for α-smooth muscle actin and several other contractile proteins; 2) ‘inflammatory’ CAFs with elevated expression of inflammatory cytokines; and 3) a CAF subpopulation expressing major histocompatibility complex (MHC) class II proteins that are generally expressed in antigen-presenting cells. Comparison of 4T1-derived CAFs to CAFs from pancreatic cancer revealed that these three CAF subpopulations exist in both tumor types. Interestingly, cells with inflammatory and MHC class II-expressing CAF profiles were also detected in normal breast/pancreas tissue, suggesting that these phenotypes are not tumor microenvironment-induced. This work enhances our understanding of CAF heterogeneity, and specifically targeting these CAF subpopulations could be an effective therapeutic approach for treating highly aggressive TNBCs.

Soluble ST2: A complex and diverse role in several diseases

The Suppression of Tumorigenicity 2 protein (ST2) is a member of the interleukin (IL) 1 receptor family with transmembrane (ST2L) and soluble (sST2) isoforms that are (over)expressed in several cells in different conditions and following various triggers (e.g. inflammation, stress). The ligand of ST2 is IL-33, which on binding to ST2L results in nuclear signalling and immunomodulatory action in various cells (tumour, immune, heart). sST2, that is released in the circulation, functions as a »decoy« receptor of IL-33 and inhibits IL-33/ST2L signalling and beneficial effects. The importance and role of the ST2/IL-33 axis and sST2 have been evaluated and confirmed in several inflammatory, cancer and cardiac diseases. sST2 is involved in homeostasis/pathogenesis of these diseases, as the counterbalance/response on IL-33/ST2L axis activation, which is triggered and expressed during developing fibrosis, tissue damage/inflammation and remodelling. In clinical studies, sST2 has been recognised as an important prognostic marker in patients with cardiac disease, including patients with chronic kidney disease where specific characteristics of sST2 enable better assessment of the risk of End-Stage Renal Disease patients on dialysis. sST2 is also recognised as an important marker for monitoring treatment in heart failure patients. However, accurate measurement and interpretation of ST2 concentration in serum/plasma samples for routine and research applications require the use of appropriate methods and recognition of essential characteristics of both the methods and the analyte that may influence the result. sST2, as one of the most promising disease biomarkers, is deserving of further study and wider application in clinical practice.

ILC2s: New Actors in Tumor Immunity

Innate lymphoid cells (ILCs) represent the most recently identified family of innate lymphocytes that act as first responders, maintaining tissue homeostasis and protecting epithelial barriers. In the last few years, group 2 ILCs (ILC2s) have emerged as key regulators in several immunological processes such as asthma and allergy. Whilst ILC2s are currently being evaluated as novel targets for immunotherapy in these diseases, their involvement in tumor immunity has only recently begun to be deciphered. Here, we provide a comprehensive overview of the pleiotropic roles of ILC2s in different tumor settings. Furthermore, we discuss how different therapeutic approaches targeting ILC2s could improve the efficacy of current tumor immunotherapies.

Functional variant of IL33 is associated with survival of osteosarcoma patients

Objectives

Previous genome-wide association study showed that GLDC/IL33 loci were associated with overall survival in patients with osteosarcoma (OS). We performed a replication study to explore whether variants of GLDC/IL33 are associated with the survival of OS patients and to further verify their functional role in the gene expression.

Methods

A total of 216 patients with OS were enrolled. The overall survival time was calculated from the date of diagnosis till the date of last follow-up or mortality. Two SNPs were genotyped, including rs55933544 and rs74438701. OS specimens were obtained from 72 patients during surgery. The gene expression level of IL33 and GLDC was evaluated by qPCR. Patients were classified into two groups according to the 5-year overall survival (death/survival). The chi-square test was used to analyze difference of genotype frequency. The Student t-test was used to compare the gene expression level between different genotypes. Cumulative survival time was calculated by the Kaplan–Meier method and analyzed by the log-rank test.

Results

Genotype TT of rs55933544 was significantly associated with the event of death (0.176 vs. 0.061, p < 0.001). Patients with no risk allele T of rs55933544 showed a 5-year overall survival of 81.4% (110/141), which was significantly higher than an overall survival of 55.0% (29/54) for patients with one risk allele and 44.8% (12/21) for patients with two risk alleles (p < 0.01). Genotype TT of rs55933544 were indicative of remarkably lower expression of IL33 than genotype CC (0.00041 ± 0.00025 vs. 0.00065 ± 0.00031, p = 0.04). Patients with low IL33 expression presented remarkably worse survival as compared with the patients with high IL33 expression (p < .01)

Conclusions

Variant rs55933544 was associated with the survival time of OS patients. IL33 may contribute to a poor prognosis of OS. Further investigation into the biological mechanisms by which IL33 influences the overall survival can shed light on the improvement of clinical outcome for OS patients.

The ST2/Interleukin-33 Axis in Hematologic Malignancies: The IL-33 Paradox

Interleukin (IL)-33 is a chromatin-related nuclear interleukin that is a component of IL-1 family. IL-33 production augments the course of inflammation after cell damage or death. It is discharged into the extracellular space. IL-33 is regarded as an “alarmin” able to stimulate several effectors of the immune system, regulating numerous immune responses comprising cancer immune reactions. IL-33 has been demonstrated to influence tumorigenesis. However, as far as this cytokine is concerned, we are faced with what has sometimes been defined as the IL-33 paradox. Several studies have demonstrated a relevant role of IL-33 to numerous malignancies, where it may have pro- and—less frequently—antitumorigenic actions. In the field of hematological malignancies, the role of IL-33 seems even more complex. Although we can affirm the existence of a negative role of IL-33 in Chronic myelogenos leukemia (CML) and in lymphoproliferative diseases and a positive role in pathologies such as Acute myeloid leukemia (AML), the action of IL-33 seems to be multiple and sometimes contradictory within the same pathology. In the future, we will have to learn to govern the negative aspects of activating the IL-33/ST2 axis and exploit the positive ones.

Interleukin 33/ST2 Axis Components Are Associated to Desmoplasia, a Metastasis-Related Factor in Colorectal Cancer

In colorectal cancer (CRC), cancer-associated fibroblasts (CAFs) are the most abundant component from the tumor microenvironment (TM). CAFs facilitate tumor progression by inducing angiogenesis, immune suppression and invasion, thus altering the organization/composition of the extracellular matrix (i.e., desmoplasia) and/or activating epithelial-mesenchymal transition (EMT). Soluble factors from the TM can also contribute to cell invasion through secretion of cytokines and recently, IL-33/ST2 pathway has gained huge interest as a protumor alarmin, promoting progression to metastasis by inducing changes in TM. Hence, we analyzed IL-33 and ST2 content in tumor and healthy tissue lysates and plasma from CRC patients. Tissue localization and distribution of these molecules was evaluated by immunohistochemistry (using localization reference markers α-smooth muscle actin or α-SMA and E-cadherin), and clinical/histopathological information was obtained from CRC patients. In vitro experiments were conducted in primary cultures of CAFs and normal fibroblasts (NFs) isolated from tumor and healthy tissue taken from CRC patients. Additionally, migration and proliferation analysis were performed in HT29 and HCT116 cell lines. It was found that IL-33 content increases in left-sided CRC patients with lymphatic metastasis, with localization in tumor epithelia associated with abundant desmoplasia. Although ST2 content showed similarities between tumor and healthy tissue, a decreased immunoreactivity was observed in left-sided tumor stroma, associated to metastasis related factors (advanced stages, abundant desmoplasia, and presence of tumor budding). A principal component analysis (including stromal and epithelial IL-33/ST2 and α-SMA immunoreactivity with extent of desmoplasia) allowed us to distinguish clusters of low, intermediate and abundant desmoplasia, with potential to develop a diagnostic signature with benefits for further therapeutic targets. IL-33 transcript levels from CAFs directly correlated with CRC cell line migration induced by CAFs conditioned media, with rhIL-33 inducing a mesenchymal phenotype in HT29 cells. These results indicate a role of IL-33/ST2 in tumor microenvironment, specifically in the interaction between CAFs and epithelial tumor cells, thus contributing to invasion and metastasis in left-sided CRC, most likely by activating desmoplasia.

Myeloid Derived Suppressor Cells Interactions With Natural Killer Cells and Pro-angiogenic Activities: Roles in Tumor Progression

Myeloid-derived suppressor cells (MDSCs) contribute to the induction of an immune suppressive/anergic, tumor permissive environment. MDSCs act as immunosuppression orchestrators also by interacting with several components of both innate and adaptive immunity. Natural killer (NK) cells are innate lymphoid cells functioning as primary effector of immunity, against tumors and virus-infected cells. Apart from the previously described anergy and hypo-functionality of NK cells in different tumors, NK cells in cancer patients show pro-angiogenic phenotype and functions, similar to decidual NK cells. We termed the pro-angiogenic NK cells in the tumor microenvironment "tumor infiltrating NK" (TINKs), and peripheral blood NK cells in cancer patients "tumor associated NK" (TANKs). The contribution of MDSCs in regulating NK cell functions in tumor-bearing host, still represent a poorly explored topic, and even less is known on NK cell regulation of MDSCs. Here, we review whether the crosstalk between MDSCs and NK cells can impact on tumor onset, angiogenesis and progression, focusing on key cellular and molecular interactions. We also propose that the similarity of the properties of tumor associated/tumor infiltrating NK and MDSC with those of decidual NK and decidual MDSCs during pregnancy could hint to a possible onco-fetal origin of these pro-angiogenic leukocytes.