Defective stromal remodeling and neutrophil extracellular traps in lymphoid tissues favor the transition from autoimmunity to lymphoma

Targeting neutrophil extracellular traps: A novel strategy in hematologic malignancies

Neutrophil extracellular traps (NETs) have emerged as a critical factor in malignant hematologic disease pathogenesis. These structures, comprising DNA, histones, and cytoplasmic proteins, were initially recognized for their role in immune defense against microbial threats. Growing evidence suggests that NETs contribute to malignant cell progression and dissemination, representing a double-edged sword. However, there is a paucity of reports on its involvement in hematological disorders. A comprehensive understanding of the intricate relationship between malignant cells and NETs is necessary to explore effective therapeutic strategies. This review highlights NET formation and mechanisms underlying disease pathogenesis. Moreover, we discuss recent advancements in targeted inhibitor development for selective NET disruption, empowering precise design and efficacious therapeutic interventions for malignant hematologic diseases.

Targeting NADPH Oxidase and Integrin α5β1 to Inhibit Neutrophil Extracellular Traps-Mediated Metastasis in Colorectal Cancer

Metastasis leads to a high mortality rate in colorectal cancer (CRC). Increased neutrophil extracellular traps (NETs) formation is one of the main causes of metastasis. However, the mechanism of NETs-mediated metastasis remains unclear and effective treatments are lacking. In this study, we found neutrophils from CRC patients have enhanced NETs formation capacity and increased NETs positively correlate with CRC progression. By quantitative proteomic analysis of clinical samples and cell lines, we found that decreased secreted protein acidic and rich in cysteine (SPARC) results in massive NETs formation and integrin α5β1 is the hub protein of NETs-tumor cell interaction. Mechanistically, SPARC regulates the activation of the nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) pathway by interacting with the receptor for activated C kinase 1 (RACK1). Over-activated NADPH oxidase generates more reactive oxygen species (ROS), leading to the release of NETs. Then, NETs upregulate the expression of integrin α5β1 in tumor cells, which enhances adhesion and activates the downstream signaling pathways to promote proliferation and migration. The combination of NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI) and integrin α5β1 inhibitor ATN-161 (Ac-PHSCN-NH2) effectively suppresses tumor progression in vivo. Our work reveals the mechanistic link between NETs and tumor progression and suggests a combination therapy against NETs-mediated metastasis for CRC.

Role of Neutrophil Extracellular Traps in Health and Disease Pathophysiology: Recent Insights and Advances

Neutrophils are the principal trouper of the innate immune system. Activated neutrophils undergo a noble cell death termed NETosis and release a mesh-like structure called neutrophil extracellular traps (NETs) as a part of their defensive strategy against microbial pathogen attack. This web-like architecture includes a DNA backbone embedded with antimicrobial proteins like myeloperoxidase (MPO), neutrophil elastase (NE), histones and deploys in the entrapment and clearance of encountered pathogens. Thus NETs play an inevitable beneficial role in the host's protection. However, recent accumulated evidence shows that dysregulated and enhanced NET formation has various pathological aspects including the promotion of sepsis, pulmonary, cardiovascular, hepatic, nephrological, thrombotic, autoimmune, pregnancy, and cancer diseases, and the list is increasing gradually. In this review, we summarize the NET-mediated pathophysiology of different diseases and focus on some updated potential therapeutic approaches against NETs.

Prediction of prognosis and immunotherapy response in breast cancer based on neutrophil extracellular traps-related classification

Neutrophil extracellular traps (NETs), a network of DNA histone complexes and proteins released by activated neutrophils, have been demonstrated to be associated with inflammation, infection related immune response and tumorigenesis in previous reports. However, the relationship between NETs related genes and breast cancer remains controversial. In the study, we retrieved transcriptome data and clinical information of BRCA patients from The Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus (GEO) datasets. The expression matrix of neutrophil extracellular traps (NETs) related genes was generated and consensus clustering was performed by Partitioning Around Medoid (PAM) to classify BRCA patients into two subgroups (NETs high group and NETs low group). Subsequently, we focus on the differentially expressed genes (DEGs) between the two NETs-related subgroups and further explored NETs enrichment related signaling pathways by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. In addition, we constructed a risk signature model by LASSO Cox regression analysis to evaluate the association between riskscore and prognosis. Even more, we explored the landscape of the tumor immune microenvironment and the expression of immune checkpoints related genes as well as HLA genes between two NETs subtypes in breast cancer patients. Moreover, we found and validated the correlation of different immune cells with risk score, as well as the response to immunotherapy in different subgroups of patients was detected by Tumor Immune Dysfunction and Exclusion (TIDE) database. Ultimately, a nomogram prognostic prediction model was established to speculate on the prognosis of breast cancer patients. The results suggest that high riskscore is associated with poor immunotherapy response and adverse clinical outcomes in breast cancer patients. In conclusion, we established a NETs-related stratification system that is beneficial for guiding the clinical treatment and predicting prognosis of BRCA.

Intracellular osteopontin protects from autoimmunity-driven lymphoma development inhibiting TLR9-MYD88-STAT3 signaling

BACKGROUND

Autoimmune disorders, including Systemic Lupus Erythematosus (SLE), are associated with increased incidence of hematological malignancies. The matricellular protein osteopontin (OPN) has been linked to SLE pathogenesis, as SLE patients show increased serum levels of OPN and often polymorphisms in its gene. Although widely studied for its pro-tumorigenic role in different solid tumours, the role of OPN in autoimmunity-driven lymphomagenesis has not been investigated yet.

METHODS

To test the role of OPN in the SLE-associated lymphomagenesis, the SLE-like prone Fas^lpr/lpr mutation was transferred onto an OPN-deficient background. Spleen from Fas^lpr/lpr and OPN-/-Fas^lpr/lpr mice, as well as purified B cells, were analysed by histopathology, flow cytometry, Western Blot, immunohistochemistry, immunofluorescence and gene expression profile to define lymphoma characteristics and investigate the molecular mechanisms behind the observed phenotype. OPN cellular localization in primary splenic B cells and mouse and human DLBCL cell lines was assessed by confocal microscopy. Finally, gain of function experiments, by stable over-expression of the secreted (sOPN) and intracellular OPN (iOPN) in OPN-/-Fas^lpr/lpr -derived DLBCL cell lines, were performed for further validation experiments.

RESULTS

Despite reduced autoimmunity signs, OPN-/-Fas^lpr/lpr mice developed splenic lymphomas with higher incidence than Fas^lpr/lpr counterparts. In situ and ex vivo analysis featured such tumours as activated type of diffuse large B cell lymphoma (ABC-DLBCL), expressing BCL2 and c-MYC, but not BCL6, with activated STAT3 signaling. OPN-/-Fas^lpr/lpr B lymphocytes showed an enhanced TLR9-MYD88 signaling pathway, either at baseline or after stimulation with CpG oligonucleotides, which mimic dsDNA circulating in autoimmune conditions. B cells from Fas^lpr/lpr mice were found to express the intracellular form of OPN. Accordingly, gene transfer-mediated re-expression of iOPN, but not of its secreted isoform, into ABC-DLBCL cell lines established from OPN-/-Fas^lpr/lpr mice, prevented CpG-mediated activation of STAT3, suggesting that the intracellular form of OPN may represent a brake to TLR9 signaling pathway activation.

CONCLUSION

These data indicate that, in the setting of SLE-like syndrome in which double strand-DNA chronically circulates and activates TLRs, B cell intracellular OPN exerts a protective role in autoimmunity-driven DLBCL development, mainly acting as a brake in the TLR9-MYD88-STAT3 signaling pathway.

GZMKhigh CD8+ T effector memory cells are associated with CD15high neutrophil abundance in non-metastatic colorectal tumors and predict poor clinical outcome

CD8⁺ T cells are a major prognostic determinant in solid tumors, including colorectal cancer (CRC). However, understanding how the interplay between different immune cells impacts on clinical outcome is still in its infancy. Here, we describe that the interaction of tumor infiltrating neutrophils expressing high levels of CD15 with CD8⁺ T effector memory cells (T_EM) correlates with tumor progression. Mechanistically, stromal cell-derived factor-1 (CXCL12/SDF-1) promotes the retention of neutrophils within tumors, increasing the crosstalk with CD8⁺ T cells. As a consequence of the contact-mediated interaction with neutrophils, CD8⁺ T cells are skewed to produce high levels of GZMK, which in turn decreases E-cadherin on the intestinal epithelium and favors tumor progression. Overall, our results highlight the emergence of GZMK^high CD8⁺ T_EM in non-metastatic CRC tumors as a hallmark driven by the interaction with neutrophils, which could implement current patient stratification and be targeted by novel therapeutics.

Regulated cell death (RCD) in cancer: key pathways and targeted therapies

Regulated cell death (RCD), also well-known as programmed cell death (PCD), refers to the form of cell death that can be regulated by a variety of biomacromolecules, which is distinctive from accidental cell death (ACD). Accumulating evidence has revealed that RCD subroutines are the key features of tumorigenesis, which may ultimately lead to the establishment of different potential therapeutic strategies. Hitherto, targeting the subroutines of RCD with pharmacological small-molecule compounds has been emerging as a promising therapeutic avenue, which has rapidly progressed in many types of human cancers. Thus, in this review, we focus on summarizing not only the key apoptotic and autophagy-dependent cell death signaling pathways, but the crucial pathways of other RCD subroutines, including necroptosis, pyroptosis, ferroptosis, parthanatos, entosis, NETosis and lysosome-dependent cell death (LCD) in cancer. Moreover, we further discuss the current situation of several small-molecule compounds targeting the different RCD subroutines to improve cancer treatment, such as single-target, dual or multiple-target small-molecule compounds, drug combinations, and some new emerging therapeutic strategies that would together shed new light on future directions to attack cancer cell vulnerabilities with small-molecule drugs targeting RCD for therapeutic purposes.

The emerging role of neutrophilic extracellular traps in intestinal disease

Neutrophil extracellular traps (NETs) are extracellular reticular fibrillar structures composed of DNA, histones, granulins and cytoplasmic proteins that are delivered externally by neutrophils in response to stimulation with various types of microorganisms, cytokines and host molecules, etc. NET formation has been extensively demonstrated to trap, immobilize, inactivate and kill invading microorganisms and acts as a form of innate response against pathogenic invasion. However, NETs are a double-edged sword. In the event of imbalance between NET formation and clearance, excessive NETs not only directly inflict tissue lesions, but also recruit pro-inflammatory cells or proteins that promote the release of inflammatory factors and magnify the inflammatory response further, driving the progression of many human diseases. The deleterious effects of excessive release of NETs on gut diseases are particularly crucial as NETs are more likely to be disrupted by neutrophils infiltrating the intestinal epithelium during intestinal disorders, leading to intestinal injury, and in addition, NETs and their relevant molecules are capable of directly triggering the death of intestinal epithelial cells. Within this context, a large number of NETs have been reported in several intestinal diseases, including intestinal infections, inflammatory bowel disease, intestinal ischemia–reperfusion injury, sepsis, necrotizing enterocolitis, and colorectal cancer. Therefore, the formation of NET would have to be strictly monitored to prevent their mediated tissue damage. In this review, we summarize the latest knowledge on the formation mechanisms of NETs and their pathophysiological roles in a variety of intestinal diseases, with the aim of providing an essential directional guidance and theoretical basis for clinical interventions in the exploration of mechanisms underlying NETs and targeted therapies.

Neutrophils-From Bone Marrow to First-Line Defense of the Innate Immune System

Neutrophils (polymorphonuclear cells; PMNs) form a first line of defense against pathogens and are therefore an important component of the innate immune response. As a result of poorly controlled activation, however, PMNs can also mediate tissue damage in numerous diseases, often by increasing tissue inflammation and injury. According to current knowledge, PMNs are not only part of the pathogenesis of infectious and autoimmune diseases but also of conditions with disturbed tissue homeostasis such as trauma and shock. Scientific advances in the past two decades have changed the role of neutrophils from that of solely immune defense cells to cells that are responsible for the general integrity of the body, even in the absence of pathogens. To better understand PMN function in the human organism, our review outlines the role of PMNs within the innate immune system. This review provides an overview of the migration of PMNs from the vascular compartment to the target tissue as well as their chemotactic processes and illuminates crucial neutrophil immune properties at the site of the lesion. The review is focused on the formation of chemotactic gradients in interaction with the extracellular matrix (ECM) and the influence of the ECM on PMN function. In addition, our review summarizes current knowledge about the phenomenon of bidirectional and reverse PMN migration, neutrophil microtubules, and the microtubule organizing center in PMN migration. As a conclusive feature, we review and discuss new findings about neutrophil behavior in cancer environment and tumor tissue.

Optimal regulation of tumour-associated neutrophils in cancer progression

In a tumour microenvironment, tumour-associated neutrophils could display two opposing differential phenotypes: anti-tumour (N1) and pro-tumour (N2) effector cells. Converting N2 to N1 neutrophils provides innovative therapies for cancer treatment. In this study, a mathematical model for N1-N2 dynamics describing the cancer survival and immune inhibition in response to TGF-β and IFN-β is considered. The effects of exogenous intervention of TGF-β inhibitor and IFN-β are examined in order to enhance N1 recruitment to combat tumour progression. Our approach employs optimal control theory to determine drug infusion protocols that could minimize tumour volume with least administration cost possible. Four optimal control scenarios corresponding to different therapeutic strategies are explored, namely, TGF-β inhibitor control only, IFN-β control only, concomitant TGF-β inhibitor and IFN-β controls, and alternating TGF-β inhibitor and IFN-β controls. For each scheme, different initial conditions are varied to depict different pathophysiological condition of a cancer patient, leading to adaptive treatment schedule. TGF-β inhibitor and IFN-β drug dosages, total drug amount, infusion times and relative cost of drug administrations are obtained under various circumstances. The control strategies achieved could guide in designing individualized therapeutic protocols.

The role of lymphoid tissue SPARC in the pathogenesis and response to treatment of multiple myeloma

Background

Despite the significant progress in the treatment of multiple myeloma (MM), the disease remains untreatable and its cure is still an unmet clinical need. Neoplastic transformation in MM is initiated in the germinal centers (GCs) of secondary lymphoid tissue (SLT) where B cells experience extensive somatic hypermutation induced by follicular dendritic cells (FDCs) and T-cell signals.

Objective

We reason that secreted protein acidic and rich in cysteine (SPARC), a common stromal motif expressed by FDCs at the origin (SLTs) and the destination (BM) of MM, plays a role in the pathogenesis of MM, and, here, we sought to investigate this role.

Methods

There were 107 BM biopsies from 57 MM patients (taken at different time points) together with 13 control specimens assessed for SPARC gene and protein expression and compared with tonsillar tissues. In addition, regulation of myeloma-promoting genes by SPARC-secreting FDCs was assessed in in vitro GC reactions (GCRs).

Results

SPARC gene expression was confirmed in both human primary (BM) and secondary (tonsils) lymphoid tissues, and the expression was significantly higher in the BM. Sparc was detectable in the BM and tonsillar lysates, co-localized with the FDC markers in both tissues, and stimulation of FDCs in vitro induced significantly higher levels of SPARC expression than unstimulated controls. In addition, SPARC inversely correlated with BM PC infiltration, ISS staging, and ECOG performance of the MM patients, and in vitro addition of FDCs to lymphocytes inhibited the expression of several oncogenes associated with malignant transformation of PCs.

Conclusion

FDC-SPARC inhibits several myelomagenic gene expression and inversely correlates with PC infiltration and MM progression. Therapeutic induction of SPARC expression through combinations of the current MM drugs, repositioning of non-MM drugs, or novel drug discovery could pave the way to better control MM in clinically severe and drug-resistant patients.

Casting a NET on cancer: the multiple roles for neutrophil extracellular traps in cancer

PURPOSE OF REVIEW

The role of the innate immune system has become widely appreciated in cancer and cancer-associated disorders. Neutrophils, the most abundant circulating leukocytes, have prognostic value in determining cancer progression and survival. One of the ways by which neutrophils negatively impact outcome is by formation of neutrophil extracellular traps (NETs) which result in release of nuclear chromatin and bioactive proteins into the extracellular space. Here, we review the evidence for NETs contributions to cancer progression, metastasis, and cancer-associated thrombosis (CAT).

RECENT FINDINGS

NETs are increased across several cancer types and predict progression and adverse outcome. Several preclinical and clinical observations implicate NETs in promoting tumor growth, angiogenesis and metastasis via distinct pathways. Furthermore, NETs are shown to contribute to resistance to immunotherapy. NETs also emerge as key players in the prothrombotic phenotype associated with cancer that can result in potentially life-threatening arterial and venous thrombosis. Recent mechanistic insights expose several potential targets to inhibit NET formation and disrupt the interaction between NETs and tumor cells.

SUMMARY

Clinical and translational insights highlight the central role of NETs in cancer progression and metastasis, disease resistance and CAT. Targeting NETs and NET-associated pathways may represent a novel approach to treat cancer.

The Role of Neutrophils in the Pathogenesis of Chronic Lymphocytic Leukemia

Tumor-associated neutrophils appear to be a crucial element of the tumor microenvironment that actively participates in the development and progression of cancerous diseases. The increased lifespan, plasticity in changing of phenotype, and functions of neutrophils influence the course of the disease and may significantly affect survival. In patients with chronic lymphocytic leukemia (CLL), disturbances in neutrophils functions impede the effective immune defense against pathogens. Therefore, understanding the mechanism underlying such a phenomenon in CLL seems to be of great importance. Here we discuss the recent reports analyzing the phenotype and functions of neutrophils in CLL, the most common leukemia in adults. We summarize the data concerning both the phenotype and the mechanisms by which neutrophils directly support the proliferation and survival of malignant B cells.

Optimization of BCG Therapy Targeting Neutrophil Extracellular Traps, Autophagy, and miRNAs in Bladder Cancer: Implications for Personalized Medicine

Bladder cancer (BC) is the ninth most common cancer and the thirteenth most common cause of mortality worldwide. Bacillus Calmette Guerin (BCG) instillation is a common treatment option for BC. BCG therapy is associated with the less adversary effects, compared to chemotherapy, radiotherapy, and other conventional treatments. BCG could inhibit the progression and recurrence of BC by triggering apoptosis pathways, arrest cell cycle, autophagy, and neutrophil extracellular traps (NETs) formation. However, BCG therapy is not efficient for metastatic cancer. NETs and autophagy were induced by BCG and help to suppress the growth of tumor cells especially in the primary stages of BC. Activated neutrophils can stimulate autophagy pathway and release NETs in the presence of microbial pathogenesis, inflammatory agents, and tumor cells. Autophagy can also regulate NETs formation and induce production of reactive oxygen species (ROS) and NETs. Moreover, miRNAs are important regulator of gene expression. These small non-coding RNAs are also considered as an essential factor to control the levels of tumor development. However, the interaction between BCG and miRNAs has not been well-understood yet. Therefore, the present study discusses the roles of miRNAs in regulations of autophagy and NETs formation in BCG therapy in the treatment of BC. The roles of autophagy and NETs formation in BC treatment and efficiency of BCG are also discussed.

Neutrophil and Eosinophil Extracellular Traps in Hodgkin Lymphoma

Classic Hodgkin lymphoma (cHL), nodular sclerosis (NS) subtype, is characterized by the presence of Hodgkin/Reed-Sternberg (HRS) cells in an inflammatory background containing neutrophils and/or eosinophils. Both types of granulocytes release extracellular traps (ETs), web-like DNA structures decorated with histones, enzymes, and coagulation factors that promote inflammation, thrombosis, and tumor growth. We investigated whether ETs from neutrophils (NETs) or eosinophils (EETs) are detected in cHL, and evaluated their association with fibrosis. We also studied expression of protease-activated receptor-2 (PAR-2) and phospho-extracellular signal-related kinase (p-ERK), potential targets/effectors of ETs-associated elastase, in HRS cells. Expression of tissue factor (TF) was evaluated, given the procoagulant properties of ETs. We analyzed 32 HL cases, subclassified as 12 NS, 5 mixed-cellularity, 5 lymphocyte-rich, 1 lymphocyte-depleted, 4 nodular lymphocyte-predominant HL (NLPHL), and 5 reactive nodes. Notably, a majority of NS cHL cases exhibited NET formation by immunohistochemistry for citrullinated histones, with 1 case revealing abundant EETs. All other cHL subtypes as well as NLPHL were negative. Immunofluorescence microscopy confirmed NETs with filamentous/delobulated morphology. Moreover, ETs formation correlates with concurrent fibrosis (r = 0.7999; 95% CI, 0.6192-0.9002; P ≤ 0.0001). Results also showed that HRS cells in NS cHL expressed PAR-2 with nuclear p-ERK staining, indicating a neoplastic or inflammatory phenotype. Remarkably, TF was consistently detected in the endothelium of NS cHL cases compared with other subtypes, in keeping with a procoagulant status. A picture emerges whereby the release of ETs and resultant immunothrombosis contribute to the inflammatory tumor microenvironment of NS cHL. This is the first description of NETs in cHL.

SPARC-positive macrophages are the superior prognostic factor in the microenvironment of diffuse large B-cell lymphoma and independent of MYC rearrangement and double-/triple-hit status

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with respect to outcome. Features of the tumor microenvironment (TME) are associated with prognosis when assessed by gene expression profiling. However, it is uncertain whether assessment of the microenvironment can add prognostic information to the most relevant and clinically well-established molecular subgroups when analyzed by immunohistochemistry (IHC).

PATIENTS AND METHODS

We carried out a histopathologic analysis of biomarkers related to TME in a very large cohort (n = 455) of DLBCL treated in prospective trials and correlated with clinicopathologic and molecular data, including chromosomal rearrangements and gene expression profiles for cell-of-origin and TME.

RESULTS

The content of PD1+, FoxP3+ and CD8+, as well as vessel density, was not associated with outcome. However, we found a low content of CD68+ macrophages to be associated with inferior progression-free survival (PFS) and overall survival (OS; P = 0.023 and 0.040, respectively) at both univariable and multivariable analyses, adjusted for the factors of the International Prognostic Index (IPI), MYC break and BCL2/MYC and BCL6/MYC double-hit status. The subgroup of PDL1+ macrophages was not associated with survival. Instead, secreted protein acidic and cysteine rich (SPARC)-positive macrophages were identified as the subtype of macrophages most associated with survival. SPARC-positive macrophages and stromal cells directly correlated with favorable PFS and OS (both, P[log rank] <0.001, P[trend] < 0.001). The association of SPARC with prognosis was independent of the factors of the IPI, MYC double-/triple-hit status, Bcl2/c-myc double expression, cell-of-origin subtype and a recently published gene expression signature [lymphoma-associated macrophage interaction signature (LAMIS)].

CONCLUSIONS

SPARC expression in the TME detected by a single IHC staining with fair-to-good interobserver reproducibility is a powerful prognostic parameter. Thus SPARC expression is a strong candidate for risk assessment in DLBCL in daily practice.

Stromal Neutrophil Extracellular Trap Density Is an Independent Prognostic Factor for Cervical Cancer Recurrence

BACKGROUND

Emerging evidence indicates that the tumor microenvironment influences tumor progression and patient prognosis through various inflammatory cells. Polymorphonuclear neutrophils (PMNs) and their functional structures termed neutrophil extracellular traps (NETs) are prominent constituents of several malignant tumors and affect the tumor microenvironment and cancer evolution. Here, we investigate the prognostic value of PMNs and NETs for recurrence in patients with cervical cancer.

METHODS

The study comprised 126 cervical cancer patients who were retrospectively enrolled. CD66b+ neutrophils and myeloperoxidase/citrullinated histone H3 (MPO/H3Cit)-labeled NETs were assessed by immunofluorescence, and the relationships with clinical and histopathologic features and patient outcome were evaluated.

RESULTS

The highest density of CD66b+ neutrophils were observed in the stromal compartment (median 55 cells/mm2). Above median densities of stromal CD66b+ neutrophils and NETs were significantly associated with short recurrence-free survival (RFS) (P = 0.041 and P = 0.006, respectively). Multivariate analysis identified high clinical stage (hazard ratio [HR] 6.40; 95% confidence interval [CI] 3.51-11.64; P < 0.001), lymph node metastases (HR 4.69; 95% CI 3.09-9.66; P = 0.006) and high density of NETs (HR 2.66; 95% CI 1.21-5.82; P = 0.015) as independent prognostic factors for short RFS, whereas a high density of CD66b+ neutrophils was not significant. Patients with a high NET density showed worse recurrence status in every stage, but the difference was only significant for stage I (P = 0.042), not stages II, III, or IV (all P > 0.05). Combining stromal NET density and the tumor, nodes, metastasis (TNM) staging system had better prognostic accuracy for cervical cancer than the TNM staging system alone at five and six years respectively (P = 0.010 and P = 0.023).

CONCLUSION

Stromal NET density is an independent prognostic factor for RFS in cervical cancer. Combining NETs with the TNM staging system may further improve prognostic stratification.

Neutrophil Extracellular Traps (NETs): Opportunities for Targeted Therapy

Antitumor therapy, including adoptive immunotherapy, inevitably faces powerful counteraction from advanced cancer. If hematological malignancies are currently amenable to therapy with CAR-T lymphocytes (T-cells modified by the chimeric antigen receptor), solid tumors, unfortunately, show a significantly higher degree of resistance to this type of therapy. As recent studies show, the leading role in the escape of solid tumors from the cytotoxic activity of immune cells belongs to the tumor microenvironment (TME). TME consists of several types of cells, including neutrophils, the most numerous cells of the immune system. Recent studies show that the development of the tumor and its ability to metastasize directly affect the extracellular traps of neutrophils (neutrophil extracellular traps, NETs) formed as a result of the response to tumor stimuli. In addition, the nuclear DNA of neutrophils - the main component of NETs - erects a spatial barrier to the interaction of CAR-T with tumor cells. Previous studies have demonstrated the promising potential of deoxyribonuclease I (DNase I) in the destruction of NETs. In this regard, the use of eukaryotic deoxyribonuclease I (DNase I) is promising in the effort to increase the efficiency of CAR-T by reducing the NETs influence in TME. We will examine the role of NETs in TME and the various approaches in the effort to reduce the effect of NETs on a tumor.

T Cells Expressing Receptor Recombination/Revision Machinery Are Detected in the Tumor Microenvironment and Expanded in Genomically Over-unstable Models

Tumors undergo dynamic immunoediting as part of a process that balances immunologic sensing of emerging neoantigens and evasion from immune responses. Tumor-infiltrating lymphocytes (TIL) comprise heterogeneous subsets of peripheral T cells characterized by diverse functional differentiation states and dependence on T-cell receptor (TCR) specificity gained through recombination events during their development. We hypothesized that within the tumor microenvironment (TME), an antigenic milieu and immunologic interface, tumor-infiltrating peripheral T cells could reexpress key elements of the TCR recombination machinery, namely, Rag1 and Rag2 recombinases and Tdt polymerase, as a potential mechanism involved in the revision of TCR specificity. Using two syngeneic invasive breast cancer transplantable models, 4T1 and TS/A, we observed that Rag1, Rag2, and Dntt in situ mRNA expression characterized rare tumor-infiltrating T cells. In situ expression of the transcripts was increased in coisogenic Mlh1-deficient tumors, characterized by genomic overinstability, and was also modulated by PD-1 immune-checkpoint blockade. Through immunolocalization and mRNA hybridization analyses, we detected the presence of rare TDT+RAG1/2+ cells populating primary tumors and draining lymph nodes in human invasive breast cancer. Analysis of harmonized single-cell RNA-sequencing data sets of human cancers identified a very small fraction of tumor-associated T cells, characterized by the expression of recombination/revision machinery transcripts, which on pseudotemporal ordering corresponded to differentiated effector T cells. We offer thought-provoking evidence of a TIL microniche marked by rare transcripts involved in TCR shaping.

SPARC regulation of PMN clearance protects from pristane-induced lupus and rheumatoid arthritis

The secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein with unexpected immunosuppressive function in myeloid cells. We investigated the role of SPARC in autoimmunity using the pristane-induced model of lupus that, in mice, mimics human systemic lupus erythematosus (SLE). Sparc -/- mice developed earlier and more severe renal disease, multi-organ parenchymal damage, and arthritis than the wild-type counterpart. Sparc +/- heterozygous mice showed an intermediate phenotype suggesting Sparc gene dosage in autoimmune-related events. Mechanistically, reduced Sparc expression in neutrophils blocks their clearance by macrophages, through defective delivery of don't-eat-me signals. Dying Sparc -/- neutrophils that escape macrophage scavenging become source of autoantigens for dendritic cell presentation and are a direct stimulation for γδT cells. Gene profile analysis of knee synovial biopsies from SLE-associated arthritis showed an inverse correlation between SPARC and key autoimmune genes. These results point to SPARC down-regulation as a leading event characterizing SLE and rheumatoid arthritis pathogenesis.

Lipopolysaccharides increase the risk of colorectal cancer recurrence and metastasis due to the induction of neutrophil extracellular traps after curative resection

BACKGROUND

Intra-abdominal infection after curative surgery for colorectal cancer is a serious complication associated with an increased risk of recurrence. Lipopolysaccharides (LPS)-an essential component of the cell wall of Gram-negative bacteria-were found to exert a protumorigenic effect by stimulating the inflammatory pathology and formation of neutrophil extracellular traps (NETs). This study was conducted to test whether LPS-induced formation of NETs promotes the development of cancer and metastasis.

METHODS

The clinical characteristics, incidence of relapse, and serum myeloperoxidase-DNA complexes of 40 patients with infection and 40 patients without infection after curative surgery were analyzed. The effects of LPS on the induction of NETs were evaluated in a mouse model of colorectal cancer and liver metastasis. The toll-like receptor 9 (TLR9)-a DNA receptor-was knocked down to assess its effect on the mitogen-activated protein kinase pathway and activities implicated in the formation of NETs.

RESULTS

Analysis of the clinical data obtained from these patients showed the significant relation of the formation of NETs and incidence of metastasis and survival rates. Subsequent in vitro experiments revealed an increased level of citrullinated-histone H3 and myeloperoxidase-DNA in LPS-injected mice with colorectal cancer. In the mimic metastatic model, injection of LPS enhanced the metastatic capacity, which was then attenuated by DNase I. This suggested that the formation of NETs was activated by LPS. Injection of TLR9-knockdown HCT116 cells in mice, followed by induction through LPS, mitigated the level of citrullinated-histone H3 and myeloperoxidase-DNA. This finding implied that the formation of NETs was suppressed.

CONCLUSION

These findings shed light on the mechanism underlying the relationship between the elevated rate of colorectal cancer recurrence in patients who underwent surgery and the incidence of infection. This mechanism involves the protumorigenic activities of LPS-induced formation of NETs. The NETs which could be mediated by the TLR9 and the mitogen-activated protein kinase signaling pathway.

Neutrophil Extracellular Traps in Tumor Metastasis: Pathological Functions and Clinical Applications

Simple Summary

Tumor-associated neutrophils constitute an important portion of the infiltrating immune cells in the tumor microenvironment. One of the abilities of neutrophils is forming neutrophil extracellular traps. Recent studies on tumor-associated neutrophils have drawn increasing attention to the role of neutrophil extracellular traps in the tumor microenvironment. There were also some reviews summarize the pro-tumorigenic activity of NETs in tumors. The specific novelty of this article is the specific summarization on the pivotal roles of NETs in tumor invasion-metastasis cascade and the recapitulation on the potential of NETs in clinical applications.

Abstract

Neutrophil extracellular trap (NET) formation is an ability of neutrophils to capture and kill pathogens by releasing chromatin scaffolds, along with associated cytotoxic enzymes and proteases, into the extracellular space. NETs are usually stimulated by pathogenic microorganisms and their products, surgical pressure or hypoxia. Interestingly, a number of recent studies suggest that tumor cells can induce NET formation, which in turn confers tumor cell malignancy. Notably, emerging studies indicate that NETs are involved in enhancing local invasion, increasing vascular permeability and facilitating immune escape and colonization, thus promoting tumor metastasis. In this article, we review the pivotal roles of NETs in the tumor metastasis cascade. We also recapitulate the potential of NETs as a cancer prognostic biomarker and therapeutic target.

Myeloid derived suppressor cells and the release of micro-metastases from dormancy

Metastasis is the primary cause of cancer mortality and an improved understanding of its pathology is critical to the development of novel therapeutic approaches. Mechanism-based therapeutic strategies require insight into the timing of tumor cell dissemination, seeding of distant organs, formation of occult lesions and critically, their release from dormancy. Due to imaging limitations, primary tumors can only be detected when they reach a relatively large size (e.g. > 1 cm³), which, based on our understanding of tumor evolution, occurs approximately 10 years and about 30 doubling times following tumor initiation. Genomic profiling of paired primary tumors and metastases has suggested that tumor seeding at secondary sites occurs early during tumor progression and frequently, years prior to clinical diagnosis. Following seeding, tumor cells may enter into and remain in a dormant state, and if they survive and are released from dormancy, they can proliferate into an overt lesion. The timeline of tumor initiation and metastatic dormancy is regulated by tumor interactions with its microenvironment, angiogenesis, and tumor-specific cytotoxic T-lymphocyte (CTL) responses. Therefore, a better understanding of the cellular interactions responsible for immune evasion and/or tumor cell release from dormancy would facilitate the development of therapeutics targeted against this critical part of tumor progression. The immunosuppressive mechanisms mediated by myeloid-derived suppressor cells (MDSCs) contribute to tumor progression and, we posit, promote tumor cell escape from CTL-associated dormancy. Thus, while clinical and translational research has demonstrated a role for MDSCs in facilitating tumor progression and metastasis through tumor escape from adoptive and innate immune responses (T-, natural killer and B-cell responses), few studies have considered the role of MDSCs in tumor release from dormancy. In this review, we discuss MDSC expansion, driven by tumor burden associated growth factor secretion and their role in tumor cell escape from dormancy, resulting in manifest metastases. Thus, the therapeutic strategies to inhibit MDSC expansion and function may provide an approach to delay metastatic relapse and prolong the survival of patients with advanced malignancies.

Role of Microenvironment in Non-Hodgkin Lymphoma: Understanding the Composition and Biology

Lymphoma microenvironment is a dynamic and well-orchestrated network of various immune and stromal cells that is indispensable for tumor cell survival, growth, migration, immune escape, and drug resistance. Recent progress has enhanced our knowledge of the pivotal role of microenvironment in lymphomagenesis. Understanding the characteristics, functions, and contributions of various components of the tumor niche, along with its bidirectional interactions with tumor cells, is paramount. It offers the potential to identify new therapeutic targets with the ability to restore antitumor immune surveillance and eliminate the protumoral factors contributed by the tumor niche.

Myeloid cell heterogeneity in lung cancer: implication for immunotherapy

Lung is a specialized tissue where metastases from primary lung tumors takeoff and those originating from extra-pulmonary sites land. One commonality characterizing these processes is the supportive role exerted by myeloid cells, particularly neutrophils, whose recruitment is facilitated in this tissue microenvironment. Indeed, neutrophils have important part in the pathophysiology of this organ and the key mechanisms regulating neutrophil expansion and recruitment during infection can be co-opted by tumor cells to promote growth and metastasis. Although neutrophils dominate the myeloid landscape of lung cancer other populations including macrophages, dendritic cells, mast cells, basophils and eosinophils contribute to the complexity of lung cancer TME. In this review, we discuss the origin and significance of myeloid cells heterogeneity in lung cancer, which translates not only in a different frequency of immune populations but it encompasses state of activation, morphology, localization and mutual interactions. The relevance of such heterogeneity is considered in the context of tumor growth and response to immunotherapy.

The extracellular matrix: A key player in the pathogenesis of hematologic malignancies

Hematopoietic stem and progenitor cells located in the bone marrow lay the foundation for multiple lineages of mature hematologic cells. Bone marrow niches are architecturally complex with specific cellular, physiochemical, and biomechanical factors. Increasing evidence suggests that the bone marrow microenvironment contributes to the pathogenesis of hematological neoplasms. Numerous studies have deciphered the role of genetic mutations and chromosomal translocations in the development hematologic malignancies. Significant progress has also been made in understanding how the cellular components and cytokine interactions within the bone marrow microenvironment promote the evolution of hematologic cancers. Although the extracellular matrix is known to be a key player in the pathogenesis of various diseases, it's role in the progression of hematologic malignancies is less understood. In this review, we discuss the interactions between the extracellular matrix and malignant cells, and provide an overview of the role of extracellular matrix remodeling in sustaining hematologic malignancies.

Tumor-associated neutrophils as new players in immunosuppressive process of the tumor microenvironment in breast cancer

Despite the conventional reputation of neutrophils to have antibacterial properties, recent studies have put emphasis and are interested in the role of neutrophils in the spread and treatment of cancer. It has been shown that the infiltration of neutrophils, either by exerting pro- or anti-tumoral effects, probably affects tumor prognosis. Tumor-associated neutrophils (TANs) probably participate in tumor promotion and development in different ways, such as increasing genomic instability, induction of immunosuppression, and increasing angiogenesis. Despite major advances in breast cancer treatment, it is the second leading cause of death in American women. It has been revealed that inflammation is a fundamental issue in the treatment of this cancer because tumor growth, invasion, metastasis, and vascularization can be affected by inflammatory factors. It is demonstrated that enhanced neutrophil to lymphocyte ratio probably contributes to the raised rate of mortality and decreased survival among breast cancer cases. The present review explores the biology of TANs, their suspected interactions in the breast cancer microenvironment, and their functions in preserving the tumor microenvironment and progression of tumors. Furthermore, their potential as therapeutic targets and clinical biomarkers has been discussed in this paper.

The Emerging Role of Neutrophil Extracellular Traps (NETs) in Tumor Progression and Metastasis

Neutrophil Extracellular Traps (NETs) are net-like structures composed of DNA-histone complexes and proteins released by activated neutrophils. In addition to their key role in the neutrophil innate immune response, NETs are also involved in autoimmune diseases, like systemic lupus erythematosus, rheumatoid arthritis, psoriasis, and in other non-infectious pathological processes, as coagulation disorders, thrombosis, diabetes, atherosclerosis, vasculitis, and cancer. Recently, a large body of evidence indicates that NETs are involved in cancer progression and metastatic dissemination, both in animal models and cancer patients. Interestingly, a close correlation between cancer cell recruitment of neutrophils in the tumor microenvironment (Tumor Associated Neutrophils. TANs) and NET formation has been also observed either in primary tumors and metastatic sites. Moreover, NETs can also catch circulating cancer cells and promote metastasis. Furthermore, it has been reported that wake dormant cancer cells, causing tumor relapse and metastasis. This review will primarily focus on the pro-tumorigenic activity of NETs in tumors highlighting their ability to serve as a potential target for cancer therapy.

SPARC-p53: The double agents of cancer

Cancer is a complex disease with high incidence and mortality rates. The important role played by the tumor microenvironment in regulating oncogenesis, tumor growth, and metastasis is by now well accepted in the scientific community. SPARC is known to participate in tumor-stromal interactions and impact cancer growth in ambiguous ways, which either enhance or suppress cancer aggressiveness, in a context-dependent manner. p53 transcription factor, a well-established tumor suppressor, has been reported to promote tumor growth in certain situations, such as hypoxia, thus displaying a duality in its action. Although both proteins are being tested in clinical trials, the synergistic relation between them is yet to be explored in clinical practice. In this review, we address the controversial roles of SPARC and p53 as double agents in cancer, briefly summarizing the interaction found between these two molecules and its importance in cancer.

Beclin-1 as a neutrophil-specific immune checkpoint

Neutrophils are early wound healing and inflammation regulators that, due to functional plasticity, can adopt either pro- or antitumor functions. Until recently, beclin-1 was a protein known mainly for its role as a critical regulator of autophagy. In this issue of the JCI, Tan et al. describe the effects of the beclin-1 conditional myeloid cell-specific deletion in mice, in which immunostimulation resulted in hypersensitive neutrophils. The chronic proinflammatory effect of these neutrophils triggered spontaneous B cell malignancies to develop. Such tumorigenic effects were mediated primarily by IL-21 and CD40 signaling, leading to the upregulation of tolerogenic molecules, such as IL-10 and PD-L1. The authors went on to examine samples derived from patient lymphoid malignancies and showed that beclin-1 expression in neutrophils positively correlated with pre-B cell leukemia/lymphoma. Overall, the study provides an elegant model for neutrophil-driven carcinogenesis and identifies potential targets for immunotherapy of B cell malignancies.

Neutrophil Extracellular Traps and Liver Disease

Neutrophil extracellular traps, or NETs, are heterogenous, filamentous structures which consist of extracellular DNA, granular proteins, and histones. NETs are extruded by a neutrophil in response to various stimuli. Although NETs were initially implicated in immune defense, subsequent studies have implicated NETs in a spectrum of disease processes, including autoimmune disease, thrombosis, and cancer. NETs also contribute to the pathogenesis of several common liver diseases, including alcohol-associated liver disease and portal hypertension. Although there is much interest in the therapeutic potential of NET inhibition, future clinical applications must be balanced against potential increased risk of infection.

Bone marrow niches in haematological malignancies

Haematological malignancies were previously thought to be driven solely by genetic or epigenetic lesions within haematopoietic cells. However, the niches that maintain and regulate daily production of blood and immune cells are now increasingly being recognized as having an important role in the pathogenesis and chemoresistance of haematological malignancies. Within haematopoietic cells, the accumulation of a small number of recurrent mutations initiates malignancy. Concomitantly, specific alterations of the niches, which support haematopoietic stem cells and their progeny, can act as predisposition events, facilitating mutant haematopoietic cell survival and expansion as well as contributing to malignancy progression and providing protection of malignant cells from chemotherapy, ultimately leading to relapse. In this Perspective, we summarize our current understanding of the composition and function of the specialized haematopoietic niches of the bone marrow during health and disease. We discuss disease mechanisms (rather than malignancy subtypes) to provide a comprehensive description of key niche-associated pathways that are shared across multiple haematological malignancies. These mechanisms include primary driver mutations in bone marrow niche cells, changes associated with increased hypoxia, angiogenesis and inflammation as well as metabolic reprogramming by stromal niche cells. Consequently, remodelling of bone marrow niches can facilitate immune evasion and activation of survival pathways favouring malignant haematopoietic cell maintenance, defence against excessive reactive oxygen species and protection from chemotherapy. Lastly, we suggest guidelines for the handling and biobanking of patient samples and analysis of the niche to ensure that basic research identifying therapeutic targets can be more efficiently translated to the clinic. The hope is that integrating knowledge of how bone marrow niches contribute to haematological disease predisposition, initiation, progression and response to therapy into future clinical practice will likely improve the treatment of these disorders.

Neutrophils in the Tumor Microenvironment

Neutrophils are the first responders to inflammation, infection, and injury. As one of the most abundant leukocytes in the immune system, neutrophils play an essential role in cancer progression, through multiple mechanisms, including promoting angiogenesis, immunosuppression, and cancer metastasis. Recent studies demonstrating elevated neutrophil to lymphocyte ratios suggest neutrophil as a potential therapeutic target and biomarker for disease status in cancer. This chapter will discuss the phenotypic and functional changes in the neutrophil in the tumor microenvironment, the underlying mechanism(s) of neutrophil facilitated cancer metastasis, and clinical potential of neutrophils as a prognostic/diagnostic marker and therapeutic target.

Hematological malignancies in connective tissue diseases

Chronic inflammation has profound tumor-promoting effects. Inflammatory cells are the key players in immunosurveillance against tumors, and immunosuppression is known to increase the risk of tumors. Autoimmune diseases, which manifest as loss of self-tolerance and chronic immune dysregulation, provide a perfect environment for tumor development. Aside from managing the direct inflammatory consequences of autoimmune pathogenesis, cancer risk profiles should be considered as a part of a patient's treatment. In this review, we describe the various associations of malignancies with autoimmune diseases, specifically systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, and Sjögren's syndrome, as well as discuss the mechanisms contributing to the pathogenesis of both disorders.

Myeloid loss of Beclin 1 promotes PD-L1hi precursor B cell lymphoma development

Beclin 1 (Becn1) is a key molecule in the autophagy pathway and has been implicated in cancer development. Due to the embryonic lethality of homozygous Becn1-deficient mice, the precise mechanisms and cell type-specific roles of Becn1 in regulating inflammation and cancer immunity remain elusive. Here, we report that myeloid-deficient Becn1 (Becn1ΔM) mice developed neutrophilia, were hypersusceptible to LPS-induced septic shock, and had a high risk of developing spontaneous precursor B cell (pre-B cell) lymphoma with elevated expression of immunosuppressive molecules programmed death ligand 1 (PD-L1) and IL-10. Becn1 deficiency resulted in the stabilization of MEKK3 and aberrant p38 activation in neutrophils, and mediated neutrophil-B cell interaction through Cxcl9/Cxcr3 chemotaxis. Neutrophil-B cell interplay further led to the activation of IL-21/STAT3/IRF1 and CD40L/ERK signaling and PD-L1 expression; therefore, it suppressed CD8+ T cell function. Ablation of p38 in Becn1ΔM mice prevented neutrophil inflammation and B cell tumorigenesis. Importantly, the low expression of Becn1 in human neutrophils was significantly correlated with the PD-L1 levels in pre-B acute lymphoblastic lymphoma (ALL) patients. Our findings have identified myeloid Becn1 as a key regulator of cancer immunity and therapeutic target for pre-B cell lymphomas.

Dissection of DLBCL microenvironment provides a gene expression-based predictor of survival applicable to formalin-fixed paraffin-embedded tissue

Background

Gene expression profiling (GEP) studies recognized a prognostic role for tumor microenvironment (TME) in diffuse large B-cell lymphoma (DLBCL), but the routinely adoption of prognostic stromal signatures remains limited.

Patients and methods

Here, we applied the computational method CIBERSORT to generate a 1028-gene matrix incorporating signatures of 17 immune and stromal cytotypes. Then, we carried out a deconvolution on publicly available GEP data of 482 untreated DLBCLs to reveal associations between clinical outcomes and proportions of putative tumor-infiltrating cell types. Forty-five genes related to peculiar prognostic cytotypes were selected and their expression digitally quantified by NanoString technology on a validation set of 175 formalin-fixed, paraffin-embedded DLBCLs from two randomized trials. Data from an unsupervised clustering analysis were used to build a model of clustering assignment, whose prognostic value was also assessed on an independent cohort of 40 cases. All tissue samples consisted of pretreatment biopsies of advanced-stage DLBCLs treated by comparable R-CHOP/R-CHOP-like regimens.

Results

In silico analysis demonstrated that higher proportion of myofibroblasts (MFs), dendritic cells, and CD4⁺ T cells correlated with better outcomes and the expression of genes in our panel is associated with a risk of overall and progression-free survival. In a multivariate Cox model, the microenvironment genes retained high prognostic performance independently of the cell-of-origin (COO), and integration of the two prognosticators (COO + TME) improved survival prediction in both validation set and independent cohort. Moreover, the major contribution of MF-related genes to the panel and Gene Set Enrichment Analysis suggested a strong influence of extracellular matrix determinants in DLBCL biology.

Conclusions

Our study identified new prognostic categories of DLBCL, providing an easy-to-apply gene panel that powerfully predicts patients’ survival. Moreover, owing to its relationship with specific stromal and immune components, the panel may acquire a predictive relevance in clinical trials exploring new drugs with known impact on TME.

Time for a "Plan B" in Peritoneal Metastatic Disease

Peritoneal involvement in cancer is the harbinger of a particularly unfavorable prognosis. The peritoneal cavity microenvironment is skewed toward immunoregulatory conditions promoted by macrophage populations and innate-like B-1 B cells, which provide immune privilege to malignant cell foci. In this issue of Cancer Research, Haro and colleagues demonstrate that triggering innate IgM-mediated B-1a immune responses via pathogen- or danger-associated molecular pattern recognition exerts antitumor effects on peritoneal metastases by inducing classical complement cascade activation. Exploitation of innate B-1 humoral responses and noncellular immunity is a promising strategy to counter the "castling" of metastatic tumor cells in the peritoneal immunoprivileged site.See related article by Haro et al., p. 159.

iTRAQ-based quantitative protein expression profiling of biomarkers in childhood B-cell and T-cell acute lymphoblastic leukemia

Purpose

This study screened serum proteins to identify potential biomarkers for childhood B-cell and T-cell acute lymphoblastic leukemia (ALL).

Patients and methods

Serum collected from 20 newly diagnosed B-cell ALL, 20 T-cell ALL and 20 healthy children. The peptides from these samples were subjected to iTRAQ. Differentially expressed proteins (DEPs) were further validated by ELISA in 24 B-ALL, 24 T-ALL, and 24 healthy children.

Results

Bioinformatics analysis revealed several pathways, including atherosclerosis signaling, interleukin signaling and production in macrophages and clathrin-mediated endocytosis signaling, that were closely related to childhood T-cell ALL. Furthermore, four selected proteins, namely LRG1, S100A8, SPARC and sL-selectin, were verified by ELISA. These results were consistent with the results of the proteomics analysis.

Conclusion

Serum S100A8 may serve as new diagnostic biomarkers in childhood B-cell ALL and T-cell ALL.

SPARC Is a New Myeloid-Derived Suppressor Cell Marker Licensing Suppressive Activities

Myeloid-derived suppressor cells (MDSC) are well-known key negative regulators of the immune response during tumor growth, however scattered is the knowledge of their capacity to influence and adapt to the different tumor microenvironments and of the markers that identify those capacities. Here we show that the secreted protein acidic and rich in cysteine (SPARC) identifies in both human and mouse MDSC with immune suppressive capacity and pro-tumoral activities including the induction of epithelial-to-mesenchymal transition (EMT) and angiogenesis. In mice the genetic deletion of SPARC reduced MDSC immune suppression and reverted EMT. Sparc^−/− MDSC were less suppressive overall and the granulocytic fraction was more prone to extrude neutrophil extracellular traps (NET). Surprisingly, arginase-I and NOS2, whose expression can be controlled by STAT3, were not down-regulated in Sparc^−/− MDSC, although less suppressive than wild type (WT) counterpart. Flow cytometry analysis showed equal phosphorylation of STAT3 but reduced ROS production that was associated with reduced nuclear translocation of the NF-kB p50 subunit in Sparc^−/− than WT MDSC. The limited p50 in nuclei reduce the formation of the immunosuppressive p50:p50 homodimers in favor of the p65:p50 inflammatory heterodimers. Supporting this hypothesis, the production of TNF by Sparc^−/− MDSC was significantly higher than by WT MDSC. Although associated with tumor-induced chronic inflammation, TNF, if produced at high doses, becomes a key factor in mediating tumor rejection. Therefore, it is foreseeable that an unbalance in TNF production could skew MDSC toward an inflammatory, anti-tumor phenotype. Notably, TNF is also required for inflammation-driven NETosis. The high level of TNF in Sparc^−/− MDSC might explain their increased spontaneous NET formation as that we detected both in vitro and in vivo, in association with signs of endothelial damage. We propose SPARC as a new potential marker of MDSC, in both human and mouse, with the additional feature of controlling MDSC suppressive activity while preventing an excessive inflammatory state through the control of NF-kB signaling pathway.

IL-10-producing B cells are characterized by a specific methylation signature

Among the family of regulatory B cells, the subset able to produce interleukin-10 (IL-10) is the most studied, yet its biology is still a matter of investigation. The DNA methylation profiling of the il-10 gene locus revealed a novel epigenetic signature characterizing murine B cells ready to respond through IL-10 synthesis: a demethylated region located 4.5 kb from the transcription starting site (TSS), that we named early IL10 regulatory region (eIL10rr). This feature allows to distinguish B cells that are immediately prone and developmentally committed to IL-10 production from those that require a persistent stimulation to exert an IL-10-mediated regulatory function. These late IL-10 producers are instead characterized by a delayed IL10 regulatory region (dIL10rr), a partially demethylated DNA portion located 9 kb upstream from the TSS. A demethylated region was also found in human IL-10-producing B cells and, very interestingly, in some B-cell malignancies, such as chronic lymphocytic leukemia and mantle cell lymphoma, characterized by an immunosuppressive microenvironment. Our findings define murine and human regulatory B cells as an epigenetically controlled functional state of mature B cell subsets and open a new perspective on IL-10 regulation in B cells in homeostasis and disease.

IL1R8 Deficiency Drives Autoimmunity-Associated Lymphoma Development

Chronic inflammation, including that driven by autoimmunity, is associated with the development of B-cell lymphomas. IL1R8 is a regulatory receptor belonging to the IL1R family, which negatively regulates NF-κB activation following stimulation of IL1R or Toll-like receptor family members. IL1R8 deficiency is associated with the development of severe autoimmune lupus-like disease in lpr mice. We herein investigated whether concomitant exacerbated inflammation and autoimmunity caused by the deficiency of IL1R8 could recapitulate autoimmunity-associated lymphomagenesis. We thus monitored B-cell lymphoma development during the aging of IL1R8-deficient lpr mice, observing an increased lymphoid cell expansion that evolved to diffuse large B-cell lymphoma (DLBCL). Molecular and gene-expression analyses showed that the NF-κB pathway was constitutively activated in Il1r8 ^-/-/lpr B splenocytes. In human DLBCL, IL1R8 had reduced expression compared with normal B cells, and higher IL1R8 expression was associated with a better outcome. Thus, IL1R8 silencing is associated with increased lymphoproliferation and transformation in the pathogenesis of B-cell lymphomas associated with autoimmunity.

Tumor-Associated Neutrophils in Cancer: Going Pro

The progression of cancer is not only about the tumor cell itself, but also about other involved players including cancer cell recruited immune cells, their released pro-inflammatory factors, and the extracellular matrix. These players constitute the tumor microenvironment and play vital roles in the cancer progression. Neutrophils—the most abundant white blood cells in the circulation system—constitute a significant part of the tumor microenvironment. Neutrophils play major roles linking inflammation and cancer and are actively involved in progression and metastasis. Additionally, recent data suggest that neutrophils could be considered one of the emerging targets for multiple cancer types. This review summarizes the most recent updates regarding neutrophil recruitments and functions in the tumor microenvironment as well as potential development of neutrophils-targeted putative therapeutic strategies.

Microenvironment signaling driving lymphomagenesis

PURPOSE OF REVIEW

In addition to the recent progresses in the description of the genetic landscape of B-cell non-Hodgkin's lymphomas, tumor microenvironment has progressively emerged as a central determinant of early lymphomagenesis, subclonal evolution, drug resistance, and late progression/transformation. The purpose of this review is to outline the most recent findings regarding malignant B-cell niche composition and organization supporting direct and indirect tumor-promoting functions of lymphoma microenvironment.

RECENT FINDINGS

Lymphoma supportive niche integrates a dynamic and orchestrated network of immune and stromal cell subsets producing, with a high level of spatial and kinetic heterogeneity, extracellular and membrane factors regulating tumor migration, survival, proliferation, immune escape, as well as tumor microarchitecture, and mechanical constraints. Some recent insights have improved our understanding of these various components of lymphoma microenvironment, taking into account the mechanisms underlying the coevolution of malignant and nonmalignant cells within the tumor niche.

SUMMARY

Deciphering tumor niche characteristics, functions, and origin could offer new therapeutic opportunities through the targeting of pivotal cellular and molecular components of the supportive microenvironment, favoring immune cell reactivation and infiltration, and/or limiting tumor retention within this protective niche.

Different Faces for Different Places: Heterogeneity of Neutrophil Phenotype and Function

As the most abundant leukocytes in the circulation, neutrophils are committed to innate and adaptive immune effector function to protect the human body. They are capable of killing intruding microbes through various ways including phagocytosis, release of granules, and formation of extracellular traps. Recent research has revealed that neutrophils are heterogeneous in phenotype and function and can display outstanding plasticity in both homeostatic and disease states. The great flexibility and elasticity arm neutrophils with important regulatory and controlling functions in various disease states such as autoimmunity and inflammation as well as cancer. Hence, this review will focus on recent literature describing neutrophils' variable and diverse phenotypes and functions in different contexts.

Role of tumor-associated neutrophils in regulation of tumor growth in lung cancer development: A mathematical model

Neutrophils display rapid and potent innate immune responses in various diseases. Tumor-associated neutrophils (TANs) however either induce or overcome immunosuppressive functions of the tumor microenvironment through complex tumor-stroma crosstalk. We developed a mathematical model to address the question of how phenotypic alterations between tumor suppressive N1 TANS, and tumor promoting N2 TANs affect nonlinear tumor growth in a complex tumor microenvironment. The model provides a visual display of the complex behavior of populations of TANs and tumors in response to various TGF-β and IFN-β stimuli. In addition, the effect of anti-tumor drug administration is incorporated in the model in an effort to achieve optimal anti-tumor efficacy. The simulation results from the mathematical model were in good agreement with experimental data. We found that the N2-to-N1 ratio (N21R) index is positively correlated with aggressive tumor growth, suggesting that this may be a good prognostic factor. We also found that the antitumor efficacy increases when the relative ratio (Dap) of delayed apoptotic cell death of N1 and N2 TANs is either very small or relatively large, providing a basis for therapeutically targeting prometastatic N2 TANs.

Neutrophil Extracellular Traps Induced by IL8 Promote Diffuse Large B-cell Lymphoma Progression via the TLR9 Signaling

PURPOSE

More than 30% of patients with diffuse large B-cell lymphoma (DLBCL) experience treatment failure after first-line therapy. Neutrophil extracellular traps (NETs), a pathogen-trapping structure in tumor microenvironment, can promote the transition of autoimmunity to lymphomagenesis. Here, we investigate whether NETs play a novel role in DLBCL progression and its underlying mechanism.Experimental Design: NETs in DLBCL tumor samples and plasma were detected by immunofluorescence and ELISA, respectively. The correlation between NETs and clinical features were analyzed. The effects of NETs on cellular proliferation and migration and mechanisms were explored, and the mechanism of NET formation was also studied by a series of in vitro and in vivo assays.

RESULTS

Higher levels of NETs in plasma and tumor tissues were associated with dismal outcome in patients with DLBCL. Furthermore, we identified NETs increased cell proliferation and migration in vitro and tumor growth and lymph node dissemination in vivo. Mechanistically, DLBCL-derived IL8 interacted with its receptor (CXCR2) on neutrophils, resulting in the formation of NETs via Src, p38, and ERK signaling. Newly formed NETs directly upregulated the Toll-like receptor 9 (TLR9) pathways in DLBCL and subsequently activated NFκB, STAT3, and p38 pathways to promote tumor progression. More importantly, disruption of NETs, blocking IL8-CXCR2 axis or inhibiting TLR9 could retard tumor progression in preclinical models.

CONCLUSIONS

Our data reveal a tumor-NETs aggressive interaction in DLBCL and indicate that NETs is a useful prognostic biomarker and targeting this novel cross-talk represents a new therapeutic opportunity in this challenging disease.