Search

Summary: Antigen cross‐priming of CD8+ T cells is a critical process necessary for the effective expansion and activation of CD8+ T cells endowed with the ability to recognize and destroy tumor cells. The cross‐presentation of tumor antigens to cross‐prime CD8+ T cells is mainly mediated, if not only, by a subset of professional antigen‐presenting cells termed type‐1 conventional dendritic cells (cDC1). The demise of malignant cells can be immunogenic if it occurs in the context of premortem stress. These ways of dying are termed immunogenic cell death (ICD) and are associated with biochemical features favoring cDC1 for the efficient cross‐priming of tumor antigens. Immunosurveillance and the success of immunotherapies heavily rely on the ability of cytotoxic immune cells, primarily CD8+ T cells and NK cells, to detect and eliminate tumor cells through mechanisms collectively known as cytotoxicity. Recent studies have revealed the significance of NK‐ and CTL‐mediated cytotoxicity as a prominent form of immunogenic cell death, resulting in mechanisms that promote and sustain antigen‐specific immune responses. This review focuses on the mechanisms underlying the cross‐presentation of antigens released during tumor cell killing by cytotoxic immune cells, with an emphasis on the role of cDC1 cells. Indeed, cDC1s are instrumental in the effectiveness of most immunotherapies, underscoring the significance of tumor antigen cross‐priming in contexts of immunogenic cell death. The notion of the potent immunogenicity of cell death resulting from NK or cytotoxic T lymphocyte (CTL)‐mediated cytotoxicity has far‐reaching implications for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

NK‐cell reactivity against cancer is conceivably suppressed in the tumor microenvironment by the interaction of the inhibitory receptor NKG2A with the non‐classical MHC‐I molecules HLA‐E in humans or Qa‐1b in mice. We found that intratumoral delivery of NK cells attains significant therapeutic effects only if co‐injected with anti‐NKG2A and anti‐Qa‐1b blocking monoclonal antibodies against solid mouse tumor models. Such therapeutic activity was contingent on endogenous CD8 T cells and type‐1 conventional dendritic cells (cDC1). Moreover, the anti‐tumor effects were enhanced upon combination with systemic anti‐PD‐1 mAb treatment and achieved partial abscopal efficacy against distant non‐injected tumors. In xenografted mice bearing HLA‐E‐expressing human cancer cells, intratumoral co‐injection of activated allogeneic human NK cells and clinical‐grade anti‐NKG2A mAb (monalizumab) synergistically achieved therapeutic effects. In conclusion, these studies provide evidence for the clinical potential of intratumoral NK cell‐based immunotherapies that exert their anti‐tumor efficacy as a result of eliciting endogenous T‐cell responses. Synopsis: An approach that involves intratumoral injections of NK cells together with neutralizing antibodies against the NKG2A inhibitory receptor was developed, aiming at extending the efficacy of NK cell‐based immunotherapies to solid malignances. Intratumoral co‐injection of pre‐activated NK cells and NKG2A neutralizing antibodies achieves synergistic anti‐tumor activity against solid mouse tumor models.CD8 T cell‐ and cDC1 responses mediate the anti‐tumor efficacy of intratumoral NK cells and anti‐NKG2A/Qa‐1b mAb administrations.Systemic anti‐PD‐1 mAb injections synergistically enhance the efficacy of intratumoral NK cells + anti‐NKG2A/Qa‐1b mAbs.Intratumoral delivery of human NK cells and monalizumab (anti‐NKG2A) to xenografted mouse tumors exerts synergistic effects. [ABSTRACT FROM AUTHOR]

Endometrial tumors show substantial heterogeneity in their immune microenvironment. This heterogeneity could be used to improve the accuracy of current outcome prediction tools. We assessed the immune microenvironment of 235 patients diagnosed with low‐grade, early‐stage endometrial cancer. Multiplex quantitative immunofluorescence was carried out to measure CD8, CD68, FOXP3, PD‐1, and PD‐L1 markers, as well as cytokeratin (CK), on tissue microarrays. Clustering results revealed five robust immune response patterns, each associated with specific immune populations, cell phenotypes, and cell spatial clustering. Most samples (69%) belonged to the immune‐desert subtype, characterized by low immune cell densities. Tumor‐infiltrating lymphocyte (TIL)‐rich samples (4%) displayed high CD8+ T‐cell infiltration, as well as a high percentage of CD8/PD‐1+ cells. Immune‐exclusion samples (19%) displayed the lowest CD8+ infiltration combined with high PD‐L1 expression levels in CK+ tumor cells. In addition, they demonstrated high tumor cell spatial clustering as well as increased spatial proximity of CD8+/PD‐1+ and CK/PD‐L1+ cells. FOXP3 and macrophage‐rich phenotypes (3% and 4% of total samples) displayed relatively high levels of FOXP3+ regulatory T‐cells and CD68+ macrophages, respectively. These phenotypes correlated with clinical outcomes, with immune‐exclusion tumors showing an association with tumor relapse. When compared with prediction models built using routine pathological variables, models optimized with immune variables showed increased outcome prediction capacity (AUC = 0.89 versus 0.78) and stratification potential. The improved prediction capacity was independent of mismatch repair protein status and adjuvant radiotherapy treatment. Further, immunofluorescence results could be partially recapitulated using single‐marker immunohistochemistry (IHC) performed on whole tissue sections. TIL‐rich tumors demonstrated increased CD8+ T‐cells by IHC, while immune‐exclusion tumors displayed a lack of CD8+ T‐cells and frequent expression of PD‐L1 in tumor cells. Our results demonstrate the capability of the immune microenvironment to improve standard prediction tools in low‐grade, early‐stage endometrial carcinomas. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Neutrophil extracellular traps (NETs) are webs of extracellular nuclear DNA extruded by dying neutrophils infiltrating tissue. NETs constitute a defence mechanism to entrap and kill fungi and bacteria. Tumours induce the formation of NETs to the advantage of the malignancy via a variety of mechanisms shown in mouse models. Here, we investigated the presence of NETs in a variety of human solid tumours and their association with IL‐8 (CXCL8) protein expression and CD8+ T‐cell density in the tumour microenvironment. Multiplex immunofluorescence panels were developed to identify NETs in human cancer tissues by co‐staining with the granulocyte marker CD15, the neutrophil marker myeloperoxidase and citrullinated histone H3 (H3Cit), as well as IL‐8 protein and CD8+ T cells. Three ELISA methods to detect and quantify circulating NETs in serum were optimised and utilised. Whole tumour sections and tissue microarrays from patients with non‐small cell lung cancer (NSCLC; n = 14), bladder cancer (n = 14), melanoma (n = 11), breast cancer (n = 31), colorectal cancer (n = 20) and mesothelioma (n = 61) were studied. Also, serum samples collected retrospectively from patients with metastatic melanoma (n = 12) and NSCLC (n = 34) were ELISA assayed to quantify circulating NETs and IL‐8. NETs were detected in six different human cancer types with wide individual variation in terms of tissue density and distribution. At least in NSCLC, bladder cancer and metastatic melanoma, NET density positively correlated with IL‐8 protein expression and inversely correlated with CD8+ T‐cell densities. In a series of serum samples from melanoma and NSCLC patients, a positive correlation between circulating NETs and IL‐8 was found. In conclusion, NETs are detectable in formalin‐fixed human biopsy samples from solid tumours and in the circulation of cancer patients with a considerable degree of individual variation. NETs show a positive association with IL‐8 and a trend towards a negative association with CD8+ tumour‐infiltrating lymphocytes. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

In humans, IL‐8 (CXCL8) is a key chemokine for chemotaxis of polymorphonuclear leukocytes and monocytes/macrophages when acting on CXCR1 and CXCR2. CXCL8 activity on neutrophils includes chemotaxis and eliciting the extrusion of neutrophil extracellular traps (NETs). In this study, we show that concentrations of IL‐8 that induce NETosis surpass in at least one order of magnitude those required to elicit chemoattraction in human neutrophils. IL‐8‐induced NETosis was less dependent on G‐proteins than migration, while extracellular Ca+2 chelation similarly inhibited both processes. Reactive oxygen species (ROS) were more important for NETosis than for chemotaxis as evidenced by neutralization with N‐acetyl ‐cysteine. Interestingly, selective blockade with anti‐CXCR1 mAb inhibited NETosis much more readily than chemotaxis, while pharmacological inhibition of both CXCR1 and CXCR2, or selective inhibition for CXCR2 alone, similarly inhibited both functions. Together, these results propose a model according to which low concentrations of IL‐8 in a gradient attract neutrophils to the inflammatory foci, while high receptor‐saturating concentrations of IL‐8 give rise to NETosis once leukocytes reach the core of the inflammatory insult. [ABSTRACT FROM AUTHOR]

Sunitinib is one of the most widely used targeted therapeutics for renal cell carcinoma (RCC), but acquired resistance against targeted therapies remains a major clinical challenge. To dissect mechanisms of acquired resistance and unravel reliable predictive biomarkers for sunitinib in RCC, we sequenced the exons of 409 tumor‐suppressor genes and oncogenes in paired tumor samples from an RCC patient, obtained at baseline and after development of acquired resistance to sunitinib. From newly arising mutations, we selected, using in silico prediction models, six predicted to be deleterious, located in G6PD, LRP1B, SETD2, TET2, SYNE1, and DCC. Consistently, immunoblotting analysis of lysates derived from sunitinib‐desensitized RCC cells and their parental counterparts showed marked differences in the levels and expression pattern of the proteins encoded by these genes. Our further analysis demonstrates essential roles for these proteins in mediating sunitinib cytotoxicity and shows that their loss of function renders tumor cells resistant to sunitinib in vitro and in vivo. Finally, sunitinib resistance induced by continuous exposure or by inhibition of the six proteins was overcome by treatment with cabozantinib or a low‐dose combination of lenvatinib and everolimus. Collectively, our results unravel novel markers of acquired resistance to sunitinib and clinically relevant approaches for overcoming this resistance in RCC. What's new? Sunitinib, a tyrosine kinase inhibitor, is one of the most commonly used targeted therapeutics for treatment of metastatic renal cell carcinoma (mRCC). However, the majority of patients who initially respond eventually develop acquired resistance. In the present study, by analyzing sequential tumor biopsies from an mRCC patient who developed acquired resistance to sunitinib, the authors identified mutations in genes whose loss of function conferred sunitinib resistance to tumor cell lines and xenografted mice and went on to identify critical downstream action mechanisms. The findings may be relevant for the development of predictive biomarkers and new therapeutic strategies in mRCC. [ABSTRACT FROM AUTHOR]

Abstract: Single nucleotide polymorphisms (SNPs) may modulate individual susceptibility to carcinogens. We designed a genome‐wide association study to characterize individuals presenting extreme phenotypes of high and low risk to develop tobacco‐induced non‐small cell lung cancer (NSCLC), and we validated our results. We hypothesized that this strategy would enrich the frequencies of the alleles that contribute to the observed traits. We genotyped 2.37 million SNPs in 95 extreme phenotype individuals, that is: heavy smokers that either developed NSCLC at an early age (extreme cases); or did not present NSCLC at an advanced age (extreme controls), selected from a discovery set (n = 3631). We validated significant SNPs in 133 additional subjects with extreme phenotypes selected from databases including >39,000 individuals. Two SNPs were validated: rs12660420 (pcombined = 5.66 × 10−5; ORcombined = 2.80), mapping to a noncoding transcript exon of PDE10A; and rs6835978 (pcombined = 1.02 × 10−4; ORcombined = 2.57), an intronic variant in ATP10D. We assessed the relevance of both proteins in early‐stage NSCLC. PDE10A and ATP10DmRNA expressions correlated with survival in 821 stage I–II NSCLC patients (p = 0.01 and p < 0.0001). PDE10A protein expression correlated with survival in 149 patients with stage I–II NSCLC (p = 0.002). In conclusion, we validated two variants associated with extreme phenotypes of high and low risk of developing tobacco‐induced NSCLC. Our findings may allow to identify individuals presenting high and low risk to develop tobacco‐induced NSCLC and to characterize molecular mechanisms of carcinogenesis and resistance to develop NSCLC. [ABSTRACT FROM AUTHOR]

Antibody-dependent cellular cytotoxicity (ADCC) is a set of mechanisms that target cells coated with IgG antibodies of the proper subclasses (IgG1 in the human) to be the prey of cell-to-cell cytolysis executed by immune cells expressing FcRIIIA (CD16A). These effectors include not only natural killer (NK) cells but also other CD16+ subsets such as monocyte/macrophages, NKT cells or γδ T cells. In cancer therapy, ADCC is exploited by antibodies that selectively recognize proteins on the surface of malignant cells. An approach to enhance antitumor activity is to act on effector cells so they are increased in their numbers or enhanced in their individual (on a cell per cell basis) ADCC performance. This enhancement can be therapeutically attained by cytokines (that is, interleukin (IL)-15, IL-21, IL-18, IL-2); immunostimulatory monoclonal antibodies (that is, anti-CD137, anti-CD96, anti-TIGIT, anti-KIR, anti-PD-1); TLR agonists or by adoptive infusions of ex vivo expanded NK cells which can be genetically engineered to become more efficient effectors. In conjunction with approaches optimizing IgG1 Fc affinity to CD16, acting on effector cells offers hope to achieve synergistic immunotherapy strategies. [ABSTRACT FROM AUTHOR]

Chronic inflammation in the tumor microenvironment and evasion of the antitumor effector immune response are two of the emerging hallmarks required for oncogenesis and cancer progression. The innate immune system not only plays a critical role in perpetuating these tumor-promoting hallmarks but also in developing antitumor adaptive immune responses. Thus, understanding the dual role of the innate system in cancer immunology is required for the design of combined immunotherapy strategies able to tackle established tumors. Here, we review recent advances in the understanding of the role of cell populations and soluble components of the innate immune system in cancer, with a focus on complement, the adapter molecule Stimulator of Interferon Genes, natural killer cells, myeloid cells, and B cells. [ABSTRACT FROM AUTHOR]

CD137 (4-1BB, TNF-receptor superfamily 9) is a surface glycoprotein of the TNFR family which can be induced on a variety of leukocyte subsets. On T and NK cells, CD137 is expressed following activation and, if ligated by its natural ligand (CD137L), conveys polyubiquitination-mediated signals via TNF receptor associated factor 2 that inhibit apoptosis, while enhancing proliferation and effector functions. CD137 thus behaves as a bona fide inducible costimulatory molecule. These functional properties of CD137 can be exploited in cancer immunotherapy by systemic administration of agonist monoclonal antibodies, which increase anticancer CTLs and enhance NK-cell-mediated antibody-dependent cell-mediated cytotoxicity. Reportedly, anti-CD137 mAb and adoptive T-cell therapy strongly synergize, since (i) CD137 expression can be used to select the T cells endowed with the best activities against the tumor, (ii) costimulation of the lymphocyte cultures to be used in adoptive T-cell therapy can be done with CD137 agonist antibodies or CD137L, and (iii) synergistic effects upon coadministration of T cells and antibodies are readily observed in mouse models. Furthermore, the signaling cytoplasmic tail of CD137 is a key component of anti-CD19 chimeric antigen receptors that are used to redirect T cells against leukemia and lymphoma in the clinic. Ongoing phase II clinical trials with agonist antibodies and the presence of CD137 sequence in these successful chimeric antigen receptors highlight the importance of CD137 in oncoimmunology. [ABSTRACT FROM AUTHOR]

CD137/TNFR9/41BB was originally described as a surface molecule present on activated T and NK cells. However, its expression is broader among leukocytes, and it is also detected on hypoxic endothelial cells and inflamed blood vessels, as well as in atherosclerotic lesions. Here, we demonstrate that lymphatic endothelial cells (LECs) up-regulate CD 137 expression from undetectable baseline levels on stimulation with TNF-α, LPS, and IL-1β. CD137 cross-Unking with an agonistic mAb results in NF-κB nuclear translocation, followed by up-regulation of VCAM and a 3-fold increase in the production of the chemokine CCL21. Accordingly, there is a 50% increase in CCR7-dependent migration toward conditioned medium from activated LECs on CD 137 cross-Unking with the agonistic mAb or the natural ligand (CD137L). Such an enhancement of cell migration is also observed with monocyte-derived dendritic ceUs transmigrating across CD137-activated LEC monolayers. Using explanted human dermal tissue, we found that inflamed skin contains abundant CD137+ lymphatic vessels and that ex vivo incubation of explanted human dermis with TNF-α induces CD137 expression in lymphatic capiUaries. More interestingly, treatment with CD 137 agonistic antibody induces CCL21 expression and DC accumulation close to lymphatic vessels. Collectively, our results demonstrate that the inflammatory function of lymphatic vessels can be regulated by CD137. [ABSTRACT FROM AUTHOR]

CD137 artificial costimulation results in complete tumor rejection in several mouse models. Type I interferons (IFN) exert antitumor effects through an array of molecular functions on malignant cells, tumor stroma and immune system cells. The fact that agonist anti-CD137 mAb induce tumor regressions in mice deficient in the unique receptor for Type I IFNs (IFNAR [ABSTRACT FROM AUTHOR]

IFN-α/β link innate and adaptive immune responses by directly acting on naïve CD8 T cells. This concept unveiled in mice remains unexplored in humans. To investigate that, human CD8CD45RO cells were stimulated with beads coated with anti-CD3 and anti-CD28 mAb, mimicking Ag (type-1) and co-stimulatory (type-2) signals, in the presence or absence of IFN-α and their transcriptional profiles were defined by cDNA-microarrays. We show that IFN-α provides a strong third signal directly to human CD8 T cells resulting in regulation of critical genes for their overall activation. This transcriptional effect was substantiated at the protein level and verified by functional assays. Interestingly, the biological effects derived from this stimulation vary depending on the CD8 T-cell population. Thus, whereas IFN-α increases the proliferative capacity of naïve CD8 T cells, it inhibits or does not affect the proliferation of Ag-experienced cells, such as memory and effector CTL, including CMV-specific lymphocytes. Cytolysis and IFN-γ-secretion of all these populations are enhanced by IFN-α-derived signals, which are critical in naïve CD8 T cells for acquisition of effector functions. Our findings in human CD8 T cells are informative to understand and improve IFN-α-based therapies for viral and malignant diseases. [ABSTRACT FROM AUTHOR]

Migration of DC into lymphatic vessels ferries antigenic cargo and pro-inflammatory stimuli into the draining LN. Given that tissues under the influence of viral infections produce type I IFN, it is conceivable that these cytokines enhance DC migration in order to facilitate an antiviral immune response. Cultured lymphatic endothelium monolayers pretreated with TNF-α were used to model this phenomenon under inflammatory conditions. DC differentiated in the presence of either IFN-α2b or IFN-α5 showed enhanced adhesion to cultured lymphatic endothelial cells. These pro-adhesive effects were mediated by DC, not the lymphatic endothelium, and correlated with increased DC transmigration across lymphatic endothelial cell monolayers. Transmigration was guided by chemokines acting on DC, and blocking experiments with mAb indicated a role for LFA-1. Furthermore, incubation of DC with IFN-α led to the appearance of active conformation epitopes on the CD11a integrin chains expressed by DC. Differentiation of mouse DC in the presence of IFN-α also increased DC migration from inflammed footpads toward popliteal LN. Collectively, these results indicate a role for type I IFN in directing DC toward LN under inflammatory conditions. [ABSTRACT FROM AUTHOR]

T regulatory cells type 1 (Tr1 cells) are excellent candidates for cell therapy in multiple sclerosis (MS). The aim of our study was to assess the functional state of Tr1 cells and IL-10R signaling in patients with MS. Tr1 cells were induced in vitro by activation with anti-CD46 antibodies in controls and patients with MS. Cells were phenotyped by cytometry and suppression assays, and the expression of cytokines and transcription factors was evaluated by real-time PCR, ELISA, cytometry and Western blotting. We found that the activity of Tr1 cells and IL-10R signaling is impaired in MS patients since Tr1 cells isolated from MS patients produced less IL-10 than those obtained from controls. Indeed, the supernatants from Tr1 cells from controls did not suppress the proliferation of stimulated CD4 cells from patients with MS. Furthermore, the IL-10R signaling pathway was not fully active in CD4 cells from MS patients and these cells had higher baseline levels of SOCS3 transcripts than controls. Indeed, after in vitro IL-10 stimulation, the expression levels of the STAT1, STAT3 and IL-10RA genes were higher in MS patients than in controls. Moreover, Stat-3 phosphorylation was lower in controls than in patients after IL-10 stimulation. These results indicate that IL-10 regulatory function is impaired in patients with MS. [ABSTRACT FROM AUTHOR]

Live 17D is widely used as a prophylactic vaccine strain for yellow fever virus that induces potent neutralizing humoral and cellular immunity against the wild‐type pathogen. 17D replicates and kills mouse and human tumor cell lines but not non‐transformed human cells. Intratumoral injections with viable 17D markedly delay transplanted tumor progression in a CD8 T‐cell‐dependent manner. In mice bearing bilateral tumors in which only one is intratumorally injected, contralateral therapeutic effects are observed consistent with more prominent CD8 T‐cell infiltrates and a treatment‐related reduction of Tregs. Additive efficacy effects were observed upon co‐treatment with intratumoral 17D and systemic anti‐CD137 and anti‐PD‐1 immunostimulatory monoclonal antibodies. Importantly, when mice were preimmunized with 17D, intratumoral 17D treatment achieved better local and distant antitumor immunity. Such beneficial effects of prevaccination are in part explained by the potentiation of CD4 and CD8 T‐cell infiltration in the treated tumor. The repurposed use of a GMP‐grade vaccine to be given via the intratumoral route in prevaccinated patients constitutes a clinically feasible and safe immunotherapy approach. Synopsis: The attenuated vaccine for yellow fever virus exerts antitumor effects when intratumorally injected which are mediated by immune responses and enhanced in pre‐vaccinated mice. Repeated intratumoral injection of 17D virus stimulates antitumor responses and delays tumor growth in transplantable tumor models through a mechanism dependent on CD8+ T cells that requires cDC1 dendritic cells and functional IFNα signaling.17D intratumoral injection modifies immune infiltration in injected and distant tumors as well as in tumor draining lymph nodes.Preimmunization of mice with 17D vaccine potentiates the antitumor effects of intratumoral 17D and this beneficial effect is transferred along with CD8 T cells. [ABSTRACT FROM AUTHOR]

Copyright of European Journal of Immunology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)