Neutrophil Cytotoxicity Research Articles

Estrogen-stimulated uropathogenic E. coli mediate enhanced neutrophil responses

Urinary tract infection (UTI) is one of the most common bacterial infections worldwide and the most common cause is uropathogenic Escherichia coli (UPEC). Current research is mostly focused on how UPEC affects host factors, whereas the effect of host factors on UPEC is less studied. Our previous studies have shown that estrogen alters UPEC virulence. However, the effect of this altered UPEC virulence on neutrophils is unknown. The aim of the present study was to investigate how the altered UPEC virulence mediated by estrogen modulates neutrophil responses. We found that estradiol-stimulated CFT073 increased neutrophil phagocytosis, NETs formation and intracellular ROS production. We observed that the total ROS production from neutrophils was reduced by estradiol-stimulated CFT073. We also found that estradiol-stimulated CFT073 induced less cytotoxicity in neutrophils. Additionally, we found that several cytokines and chemokines like IL-8, IL-1β, CXCL6, MCP-1 and MCP-4 were increased upon estradiol-stimulated CFT073 infection. In conclusion, this study demonstrates that the estrogen-mediated alterations to UPEC virulence modulates neutrophil responses, most likely in a host-beneficial manner.

Serum Procalcitonin, Hematology Parameters, and Cell Morphology in Multiple Clinical Conditions and Sepsis.

The clinical value of procalcitonin (PCT) in infection diagnosis and antibiotic stewardship is still unclear. This study aimed to investigate the association between serum PCT and different clinical conditions as well as other infectious/inflammatory parameters in different septic patients in order to elucidate the value of PCT detection in infection management. Chemiluminescence immunoassay was used for serum PCT analysis. Hematology analysis was used for complete blood cell count. Digital automated cell morphology analysis was used for blood cell morphology examination. Blood, urine, and stool cultures were performed according to routine clinical laboratory standard operating procedures. C-reactive protein (CRP) was analyzed by immunoturbidimetry. Erythrocyte sedimentation rate test was performed using natural sedimentation methods. Outpatients, ICU patients, and patients under 2 years of age with respiratory infections had higher serum PCT levels. Septic patients had the highest-serum PCT levels and other infection indexes. PCT levels in the blood, urine, and stool culture-positive patients were significantly higher than in culture-negative patients. The neutrophil granulation and reactive lymphocytes were observed together with the PCT-level increments in different septic patients, and these alterations were lessened after treatment. There was no significant change in monocyte morphology between pre- and posttreatment septic patients. Serum PCT is associated with neutrophil cytotoxicity and lymphocyte morphology changes in sepsis; thus, the combination of neutrophil and lymphocyte digital cell morphology evaluations with PCT detection may be a useful examination for guiding the clinical management of sepsis.

Enhancing Neutrophil Cytotoxicity of a Panel of Clinical EGFR Antibodies by Fc Engineering to IgA3.0.

EGFR plays an essential role in cellular signaling pathways that regulate cell growth, proliferation, and survival and is often dysregulated in cancer. Several monoclonal IgG antibodies have been clinically tested over the years, which exert their function via blocking the ligand binding domain (thereby inhibiting downstream signaling) and inducing Fc-related effector functions, such as antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). However, these IgG antibodies do not optimally recruit neutrophils, which are the most abundant white blood cell population in humans. Therefore, we reformatted six therapeutic EGFR antibodies (cetuximab, panitumumab, nimotuzumab, necitumumab, zalutumumab, and matuzumab) into the IgA3.0 format, which is an IgA2 isotype adapted for clinical application. Reformatting these antibodies preserved Fab-mediated functions such as EGFR binding, growth inhibition, and ligand blockade. In addition, whole leukocyte ADCC was significantly increased when using this panel of IgA3.0 antibodies compared with their respective IgG counterparts, with no major differences between IgA3.0 antibodies. In vivo, IgA3.0 matuzumab outperformed the other antibodies, resulting in the strongest suppression of tumor outgrowth in a long intraperitoneal model. We showed that neutrophils are important for the suppression of tumor outgrowth. IgA3.0 matuzumab exhibited reduced receptor internalization compared with the other antibodies, possibly accounting for its superior in vivo Fc-mediated tumor cell killing efficacy. In conclusion, reformatting EGFR antibodies into an IgA3.0 format increased Fc-mediated killing while retaining Fab-mediated functions and could therefore be a good alternative for the currently available antibody therapies.

Enhancing IgA-mediated neutrophil cytotoxicity against neuroblastoma by CD47 blockade

BackgroundApproximately half of the neuroblastoma patients develop high-risk neuroblastoma. Current treatment involves a multimodal strategy, including immunotherapy with dinutuximab (IgG ch14.18) targeting GD2. Despite achieving promising results, the recurrence rate...

The hybrid CL-SP-D molecule has the potential to regulate xenogeneic rejection by human neutrophils more efficiently than CD47

ObjectiveInnate immunity plays a vital role in xenotransplantation. A CD47 molecule, binding to the SIRPα expressed on monocyte/macrophage cells, can suppress cytotoxicity. Particularly, the SIRPα contains ITIM, which delivers a negative signal. Our previous study demonstrated that the binding between CL-P1 and surfactant protein-D hybrid (CL-SP-D) with SIRPα regulates macrophages' phagocytic activity. In this study, we examined the effects of human CD47 and CL-SP-D expression on the inhibition of xenograft rejection by neutrophils in swine endothelial cells (SECs). MethodsWe first examined SIRPα expression on HL-60 cells, a neutrophil-like cell line, and neutrophils isolated from peripheral blood. CD47-expressing SECs or CL-SP-D-expressing SECs were generated through plasmid transfection. Subsequently, these SECs were co-cultured with HL-60 cells or neutrophils. After co-culture, the degree of cytotoxicity was calculated using the WST-8 assay. The suppressive function of CL-SP-D on neutrophils was subsequently examined, and the results were compared with those of CD47 using naïve SECs as controls. Additionally, we assessed ROS production and neutrophil NETosis. ResultsIn initial experiments, the expression of SIRPα on HL-60 and neutrophils was confirmed. Exposure to CL-SP-D significantly suppressed the cytotoxicity in HL-60 (p = 0.0038) and neutrophils (p = 0.00003). Furthermore, engagement with CD47 showed a suppressive effect on neutrophils obtained from peripheral blood (p = 0.0236) but not on HL-60 (p = 0.4244). The results of the ROS assays also indicated a significant downregulation of SEC by CD47 (p = 0.0077) or CL-SP-D (p = 0.0018). Additionally, the suppression of NETosis was confirmed (p = 0.0125) in neutrophils co-cultured with S/CL-SP-D. ConclusionThese results indicate that CL-SP-D is highly effective on neutrophils in xenogeneic rejection. Furthermore, CL-SP-D was more effective than CD47 at inhibiting neutrophil-mediated xenograft rejection.

Isolation of Cytotoxic Neutrophils from Tumor-Bearing Mouse Blood

Isolation of Cytotoxic Neutrophils from Tumor-Bearing Mouse Blood

Isolation of Cytotoxic Neutrophils from Tumor-Bearing Mouse Blood

Isolation of Cytotoxic Neutrophils from Tumor-Bearing Mouse Blood

Toll-like receptor 2, hyaluronan, and neutrophils play a key role in plaque erosion: the OPTICO-ACS study.

In one-third of patients with acute coronary syndrome (ACS), thrombosis occurs despite an intact fibrous cap (IFC) (IFC-ACS, 'plaque erosion'). Recent studies emphasize neutrophils as the immediate inflammatory response in this pathology, but their exact molecular activation patterns are still poorly understood and may represent future therapeutic targets. Thirty-two patients with IFC-ACS and matched patients with ACS with ruptured fibrous cap (RFC) (RFC-ACS) from the OPTICO-ACS study were included, and blood samples were collected from the local site of the culprit lesion and the systemic circulation. Neutrophil surface marker expression was quantified by flow cytometry. Neutrophil cytotoxicity towards endothelial cells was examined in an ex vivo co-culture assay. Secretion of active matrix metalloproteinase 9 (MMP9) by neutrophils was evaluated using zymography in supernatants and in plasma samples. Optical coherence tomography (OCT)-embedded thrombi were used for immunofluorescence analysis. Toll-like receptor 2 (TLR2) expression was higher on neutrophils from IFC-ACS than RFC-ACS patients. TLR2 stimulation increased the release of active MMP9 from local IFC-ACS-derived neutrophils, which also aggravated endothelial cell death independently of TLR2. Thrombi of IFC-ACS patients exhibited more hyaluronidase 2 with concomitant increase in local plasma levels of the TLR2 ligand: hyaluronic acid. The current study provides first in-human evidence for distinct TLR2-mediated neutrophil activation in IFC-ACS, presumably triggered by elevated soluble hyaluronic acid. Together with disturbed flow conditions, neutrophil-released MMP9 might be promoting endothelial cell loss-triggered thrombosis and therefore providing a potential future target for a phenotype-specific secondary therapeutic approach in IFC-ACS.

Disruption of the sialic acid/Siglec-9 axis improves antibody-mediated neutrophil cytotoxicity towards tumor cells.

Upregulation of surface expressed sialoglycans on tumor cells is one of the mechanisms which promote tumor growth and progression. Specifically, the interactions of sialic acids with sialic acid-binding immunoglobulin-like lectins (Siglecs) on lymphoid or myeloid cells transmit inhibitory signals and lead to suppression of anti-tumor responses. Here, we show that neutrophils express among others Siglec-9, and that EGFR and HER2 positive breast tumor cells express ligands for Siglec-9. Treatment of tumor cells with neuraminidases or a sialyl transferase inhibitor significantly reduced binding of a soluble recombinant Siglec-9-Fc fusion protein, while EGFR and HER2 expression remained unchanged. Importantly, the cytotoxic activity of neutrophils driven by therapeutic EGFR or HER2 antibodies in vitro was increased by blocking the sialic acid/Siglec interaction, either by reducing tumor cell sialylation or by a Siglec-9 blocking antibody containing an effector silenced Fc domain. In vivo a short-term xenograft mouse model confirmed the improved therapeutic efficacy of EGFR antibodies against sialic acid depleted, by a sialyltransferase inhibitor, tumor cells compared to untreated cells. Our studies demonstrate that sialic acid/Siglec interactions between tumor cells and myeloid cells can impair antibody dependent tumor cell killing, and that Siglec-9 on polymorphonuclear cells (PMN) is critically involved. Considering that PMN are often a highly abundant cell population in the tumor microenvironment, Siglec-9 constitutes a promising target for myeloid checkpoint blockade to improve antibody-based tumor immunotherapy.

Abstract 3647: Anti-tumor actions of neutrophils are mediated via STAT5 inhibition

Abstract The overall patient survival rate drops dramatically when localized prostate cancer (PCa) progresses to bone metastatic prostate cancer (BM-PCa). The treatment for BM-PCa is limited to palliative therapy, and it is currently incurable. Neutrophils are the most prevalent immune cell in the bone, and we have found that PCa enhances their recruitment and infiltration into the prostate tumor-bone microenvironment of patients with BM-PCa. Additionally, we observed that bone marrow neutrophils directly induce apoptosis of PCa cells both in vitro and in vivo and that this is mediated by the inhibition of STAT5, a transcription factor that promotes PCa progression. Moreover, STAT5 has also been found to contribute to the development of resistance to standard care androgen deprivation therapy. Neutrophils specifically target and kill only cells that express STAT5, as stable knockdown of STAT5 in BM-PCa cells makes them resistant to neutrophil-mediated cytotoxicity, while the overexpression of STAT5 in STAT5-negative PCa cells, which are generally resistant to killing by neutrophils, sensitizes them to neutrophil-mediated killing. Furthermore, transcriptomic analyses derived from the STAT5 knockdown and STAT5 overexpressing cells suggest that STAT5 expression in PCa induces pro-inflammatory signaling and that neutrophil-mediated cytotoxicity may be exerted via STAT5-induced IL-1 and/or IL-6. Preliminary data in our laboratory show that STAT5-induced production of IL-1 by PCa cells leads to their death by neutrophils, as knocking out the IL-1 receptor on neutrophils reduces their cytotoxic potential against STAT5-positive PCa cells. Interestingly, in addition to killing BM-PCa cells, we have demonstrated that bone marrow-derived neutrophils are also capable of killing pancreatic cancer cells. Further delineation of the role of neutrophils in STAT5 signaling in BM-PCa growth holds promise for enhancing neutrophil cytotoxicity in the bone which could lead to novel therapeutic options for bone metastatic prostate cancer. Citation Format: Sanjana Rajgopal, Massar Alsamraae, Diane Costanzo-Garvey, Leah Cook. Anti-tumor actions of neutrophils are mediated via STAT5 inhibition. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3647.

Panobinostat Induced Spatial In Situ Biomarkers Predictive of Anti-PD-1 Efficacy in Mouse Mammary Carcinoma.

Immunotherapies, including anti-PD-1 immune checkpoint blocking (ICB) antibodies, have revolutionized the treatment of many solid malignancies. However, their efficacy in breast cancer has been limited to a subset of patients with triple-negative breast cancer, where ICBs are routinely combined with a range of cytotoxic and targeted agents. Reliable biomarkers predictive of the therapeutic response to ICB in breast cancer are critically missing, though a combination response has been associated with immunogenic cell death (ICD). Here, we utilized a recently developed integrated analytical platform, the multiplex implantable microdevice assay (MIMA), to evaluate the presence and spatial cell relations of literature-based candidate markers predictive of ICB efficacy in luminal mouse mammary carcinoma. MIMA integrates (i) an implantable microdevice for the localized delivery of small amounts of drugs inside the tumor bed with (ii) sequential multiplex immunohistochemistry (mIHC) and spatial cell analysis pipelines to rapidly (within days) describe drug mechanisms of action and find predictive biomarkers in complex tumor tissue. We show that the expression of cleaved caspase-3, ICAM-1, neuropilin-1, myeloperoxidase, calreticulin, galectin-3, and PD-L1 were spatially associated with the efficacy of panobinostat, a pan-HDAC inhibitor that was previously shown to induce immunogenic cell death and synergize with anti-PD-1 in breast cancer. PD-L1 by itself, however, was not a reliable predictor. Instead, ICB efficacy was robustly identified through the in situ hotspot detection of galectin-3-positive non-proliferating tumor zones enriched in cell death and infiltrated by anti-tumor cytotoxic neutrophils positive for ICAM-1 and neuropilin-1. Such hotspots can be specifically detected using distance-based cluster analyses. Single-cell measurements of the functional states in the tumor microenvironment suggest that both qualitative and quantitative effects might drive effective therapy responses. Overall, the presented study provides (i) complementary biological knowledge about the earliest cell events of induced anti-tumor immunity in breast cancer, including the emergence of resistant cancer stem cells, and (ii) newly identified biomarkers in form of specific spatial cell associations. The approach used standard cell-type-, IHC-, and FFPE-based techniques, and therefore the identified spatial clustering of in situ biomarkers can be readily integrated into existing clinical or research workflows, including in luminal breast cancer. Since early drug responses were detected, the biomarkers could be especially applicable to window-of-opportunity clinical trials to rapidly discriminate between responding and resistant patients, thus limiting unnecessary treatment-associated toxicities.

Systemic Activation of Neutrophils by Immune Complexes Is Critical to IgA Vasculitis.

In IgA vasculitis (IgAV) perivascular deposition of IgA1 immune complexes (IgA-ICs) is traditionally considered the fundamental trigger for polymorphonuclear neutrophil (PMN)-mediated damage. We propose that IgA-IC deposition, although mandatory, is not sufficient alone for IgAV. Serum IgA-IC levels and IgA-IC binding to PMNs were quantified in IgAV patients and controls. Activation of PMNs was evaluated by neutrophil extracellular trap (NET) release, adherence, and cytotoxicity assays and in a flow system to mirror conditions at postcapillary venules. In vitro results were related to findings in biopsies and a mouse vasculitis model. During acute IgAV flares we observed elevated serum levels of IgA-ICs and increased IgA-IC binding to circulating PMNs. This IgA-IC binding primed PMNs with consequent lowering of the threshold for NETosis, demonstrated by significantly higher release of NETs from PMNs activated in vitro and PMNs from IgAV patients with flares compared with surface IgA-negative PMNs after flares. Blocking of FcαRI abolished these effects, and complement was not essential. In the flow system, marked NETosis only occurred after PMNs had adhered to activated endothelial cells. IgA-IC binding enhanced this PMN tethering and consequent NET-mediated endothelial cell injury. Reflecting these in vitro findings, we visualized NETs in close proximity to endothelial cells and IgA-coated PMNs in tissue sections of IgAV patients. Inhibition of NET formation and knockout of myeloperoxidase in a murine model of IC vasculitis significantly reduced vessel damage in vivo. Binding of IgA-ICs during active IgAV primes PMNs and promotes vessel injury through increased adhesion of PMNs to the endothelium and enhanced NETosis.

The chemiluminescent and enzymatic activity of blood neutrophils in patients with Graves' disease depending on hyperthyroidism compensation

BACKGROUND: Oxidative stress in Graves’ disease can potentiate the cytotoxicity of neutrophils and support autoimmune inflammation. Elimination of hyperthyroidism with conservative therapy with thiamazole only in some cases leads to remission, which determines the necessity to search an immunological markers for etiotropic therapeutic approaches in treatment of the disease.AIM: To study the chemiluminescent and enzymatic activity of peripheral blood neutrophils in patients with Graves’ disease depending on hyperthyroidism compensation to determine the intracellular targets of immunotropic treatment.MATERIALS AND METHODS: Spontaneous and zymosan-induced chemiluminescence was evaluated using a 36-channel chemiluminescence analyzer «BLM-3607» (MedBioTech, Krasnoyarsk). The reactivity of peripheral blood neutrophils was characterized by: Tmax — the rate of development of the chemiluminescent reaction, Imax — the maximum level of reactive oxygen species (ROS) synthesis and the area under the chemiluminescence curve (S — total synthesis of ROS for 90 minutes of measurement). The activity of NAD(P)-dependent dehydrogenases in neutrophils was determined using the bioluminescent method.RESULTS: The prospective study included 126 women with Graves’ disease, aged 18 to 65 years, 93 (73.81%) with compensated and 33 (26.19%) with uncompensated hyperthyroidism. In uncompensated hyperthyroidism, the indicator S of spontaneous ROS and zymosan-induced lucigenin-dependent chemiluminescence increases significantly, both relative to the control and to the values of compensated hyperthyroidism patients. Antigenic neutrophils stimulation during luminol-dependent chemiluminescence in patients with recurrent hyperthyroidism demonstrated more than tenfold increase in the total synthesis of ROS relative to the control, but no statistically significant differences with compensated hyperthyroidism patients. A high level of NADH-GDG was established in patients with recurrent hyperthyroidism, both relative to the control range and to the patients with euthyroidism.CONCLUSION: Violation of oxygen peripheral blood neutrophils metabolism in patients with euthyroidism mainly affects the production of ROS, which is associated with hyperthyroidism compensation and the immunosuppressive effect of thiamazole. In patients with recurrent hyperthyroidism, there are more changes in the production of high-energy oxidants not only at initial oxidative reactions stage, but also at the level of secondary ROS, indicating the activation of cellular response immunological mechanisms.

Recognition of Tumor Nidogen-1 by Neutrophil C-Type Lectin Receptors.

Neutrophil-mediated cytotoxicity toward tumor cells requires cell contact and is mediated by hydrogen peroxide. We have recently shown that Cathepsin G expressed on the neutrophil surface interacts with tumor RAGE, and this interaction facilitates neutrophil cytotoxicity. Interruption of the Cathepsin G–RAGE interaction led to 50–80% reduction in cytotoxicity, suggesting that additional interactions are also involved. Here we show that blocking antibodies to the C-type lectin receptors (CLRs) Clec4e and Dectin-1, but not those to NKG2D, attenuated murine neutrophil cytotoxicity towards murine tumor cells, suggesting a contributing role for these CLRs in neutrophil recognition of tumor cells. We further observed that the CLRs interact with tumor Nidogen-1 and Hspg2, two sulfated glycoproteins of the basement membrane. Both Nidogen-1 and Hspg2 were found to be expressed on the tumor cell surface. The knockdown of Nidogen-1, but not that of Hspg2, led to reduced susceptibility of the tumor cells to neutrophil cytotoxicity. Altogether, this study suggests a role for CLR–Nidogen-1 interaction in the recognition of tumor cells by neutrophils, and this interaction facilitates neutrophil-mediated killing of the tumor cells.

Effects of polysaccharides isolated from mushrooms (Lentinus edodes Berk or Agaricus blazei Murill) on the gelation of Pluronic® F127

This study evaluated the effects of polysaccharides isolated from Lentinus edodes Berk and Agaricus blazei Murill mushrooms on the gelation process of the Pluronic® F127 (F127) copolymer. The structural characterization of these biopolymers suggested the isolation of an β-glucan L. edodes Berk (LEB) and a proteoglycan complex A. blazei Murill (ABM). Both polysaccharides showed good rheological properties for developing pharmaceutical formulations with antioxidant activity and low cytotoxicity in human neutrophils. The characterization of the gels formed from the mixture of polysaccharides with aqueous solutions of F127 showed that the presence of these biopolymers reduces the temperature range in which F127 remains in the gel phase (G’ > G’’). Furthermore, the thermoresponsive behavior of F127 was not lost, which favors the development of hydrogels with potential for topical use.

Abstract P5-13-05: Multiplex spatial systems analysis of responses to spatially separate nanoliter doses of drug predicts systemic immune-modulating combination treatments in breast cancer

Abstract Most targeted and chemotherapeutic agents in use today affect both the tumor and the associated tumor microenvironment (TME) and should be combined to achieve effective control by simultaneously attacking tumor intrinsic vulnerabilities, enhancing immune surveillance, and mitigating stromal mediators of resistance. We have developed an integrated technological platform that enables rapid identification of such combinations by effective, fast and harmless assessment of TME responses to multiple drugs or drug combinations. This approach uses an implantable microdevice for delivery of dozens of treatments into spatially separated regions of a single living tumor and multiplexed histology analyses with probes for 30+ proteins to interrogate the responses of tumor epithelial cells, cancer associated fibroblasts, endothelial cells, lymphoid and myeloid immune lineages. Responses of interest include changes in differentiation state, antigenicity and immunogenic cell death. We demonstrated the utility of this platform by performing an unbiased in vivo screen to assess the effects of seven FDA approved drugs and combinations thereof on two late-stage mouse models of breast cancer with intact immunity. These studies indicated that the most effective, immunogenic, tumor cell kill was produced by the epigenetic modulator, panobinostat, and was linked with upregulation of MHC-I expression on tumor cells, and recruitment of antigen presenting macrophages and cytotoxic neutrophils. Increased expression of Galectin-3 and Neuropilin-1 on cancer stem cells and neutrophils, respectively, correlated with the therapeutic response three days after drug exposure, suggesting a functional role of these two proteins in early events of induced anti-tumor immunity. Our spatial systems analyses also revealed a key role for density of cancer stem cells (CSCs) and formation of fibroblasts/ECM barriers as potential resistance mechanisms. Addition of the BCL2 inhibitor, venetoclax, enhanced panobinostat anti-tumor activity, and the local phenotypic cell responses involving dendritic cell recruitment and clustering to CSC microculture suggested the use of anti-CD40 immunotherapy to induce maximum therapeutic effect. We demonstrated that a panobinostast-venetoclax-anti-CD40 therapeutic combination predicted from microdevice analyses was effective in whole animal studies in multiple models of breast cancer and often resulted in complete tumor control. Generalization of this approach promises to enable rapid design of personalized drug combination regimens that maximize tumor cell eradication by direct action on the tumor cells and by creating effective antitumor microenvironments. We demonstrated the utility of the approach in model systems but application in humans is now underway. Citation Format: Zuzana Tatarova, Dylan C Blumberg, Lisa M Coussens, Gordon B Mills, Oliver Jonas, Joe W Gray. Multiplex spatial systems analysis of responses to spatially separate nanoliter doses of drug predicts systemic immune-modulating combination treatments in breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-13-05.

HMGB1-Mediated Neutrophil Extracellular Trap Formation Exacerbates Intestinal Ischemia/Reperfusion-Induced Acute Lung Injury.

Influx of activated neutrophils into the lungs is the histopathologic hallmark of acute lung injury (ALI) after intestinal ischemia/reperfusion (I/R). Neutrophils can release DNA and granular proteins to form cytotoxic neutrophil extracellular traps (NETs), which promotes bystander tissue injury. However, whether NETs are responsible for the remote ALI after intestinal I/R and the mechanisms underlying the dissemination of harmful gut-derived mediators to the lungs are unknown. In the C57BL/6J mouse intestinal I/R model, DNase I-mediated degradation and protein arginine deiminase 4 (PAD4) inhibitor-mediated inhibition of NET treatments reduced NET formation, tissue inflammation, and pathological injury in the lung. High-mobility group protein B1 (HMGB1) blocking prevented NET formation and protected against tissue inflammation, as well as reduced cell apoptosis and improved survival rate. Moreover, recombinant human HMGB1 administration further drives NETs and concurrent tissue toxic injury, which in turn can be reversed by neutrophil deletion via anti-Ly6G Ab i.p. injection. Furthermore, global MyD88 deficiency regulated NET formation and alleviated the development of ALI induced by intestinal I/R. Thus, HMGB1 released from necroptotic enterocytes caused ALI after intestinal I/R by inducing NET formation. Targeting NETosis and the HMGB1 pathway might extend effective therapeutic strategies to minimize intestinal I/R-induced ALI.

The PD-L1/PD-1 Axis Blocks Neutrophil Cytotoxicity in Cancer.

The PD-L1/PD-1 axis mediates immune tolerance and promotes tumor growth and progression via the inhibition of anti-tumor immunity. Blocking the interaction between PD-L1 and PD-1 was clinically shown to be beneficial in maintaining the anti-tumor functions of the adaptive immune system. Still, the consequences of blocking the PD-L1/PD-1 axis on innate immune responses remain largely unexplored. In this context, neutrophils were shown to consist of distinct subpopulations, which possess either pro- or anti-tumor properties. PD-L1-expressing neutrophils are considered pro-tumor as they are able to suppress cytotoxic T cells and are propagated with disease progression. That said, we found that PD-L1 expression is not limited to tumor promoting neutrophils, but is also evident in anti-tumor neutrophils. We show that neutrophil cytotoxicity is effectively and efficiently blocked by tumor cell-expressed PD-1. Furthermore, the blocking of either neutrophil PD-L1 or tumor cell PD-1 maintains neutrophil cytotoxicity. Importantly, we show that tumor cell PD-1 blocks neutrophil cytotoxicity and promotes tumor growth via a mechanism independent of adaptive immunity. Taken together, these findings highlight the therapeutic potential of enhancing anti-tumor innate immune responses via blocking of the PD-L1/PD-1 axis.

DOP05 Target engagement and pharmacodynamic biomarker analysis following treatment with the oral gut-targeted HIF-1α stabilizer GB004 in a Phase 1b trial in Active Ulcerative Colitis

Abstract Background Ulcerative colitis (UC) is characterized by the loss of epithelial barrier function and chronic mucosal inflammation. GB004 is an oral, gut-targeted, small molecule stabilizer of hypoxia inducible factor (HIF-1α) that promotes epithelial repair and function. A phase 1b study was conducted in patients with active UC where trends in clinical efficacy favoring GB004 were observed. Here we report the target engagement (TE) and pharmacodynamic (PD) biomarker analysis of colon biopsies and stool samples from the phase 1b study. Methods Subjects with active UC despite 5-ASA treatment were randomized 2:1 to GB004 120 mg solution or placebo (PBO) once daily for 28 days. Colon biopsies (sigmoid and rectum) and stool samples were collected at baseline and Day 28. HIF-1a and myeloperoxidase (MPO) immunohistochemistry was performed on formalin-fixed paraffin-embedded colon biopsies. Gene expression profiling (Affymetrix HTA 2.0) was performed on mRNA extracted from colon biopsies. Fecal calprotectin (FC) and secretory IgA (sIgA) were measured from stool samples. Results presented are overall means for baseline characteristics and differences in mean (HIF-1a, MPO) and median (FC, sIgA) percent change from baseline to Day 28 for GB004 vs PBO. Results Thirty-four subjects (age 45.4 years, Mayo score 7.5, sigmoid colon Mayo endoscopic subscore 2.2, sigmoid colon Robarts Histopathology Index 14.1) were randomized to a GB004 120 mg solution (n=23) or PBO (n=11) group. GB004 demonstrated evidence of TE, with an increase in the percent of HIF-1α positive cells (+11.4%) in sigmoid colon segment sections. Tissue and stool-based PD biomarkers of intestinal inflammation associated with lamina propria neutrophil infiltration and cytotoxicity measured by the MPO+ cell count per mm2 (-7.3%) and FC (-30.4%) levels decreased. Lastly, GB004 resulted in an increase in sIgA levels (+87.16%) and transcriptional changes consistent with enhanced epithelial integrity, such as increases in ITGA6 and TJP1. Conclusion In this phase 1b study, GB004, an oral gut-targeted HIF-1α stabilizer, demonstrated TE in the sigmoid colon and histologic, fecal biomarker, and transcriptional PD effects consistent with a reduction in inflammation and mucosal healing. These observations are consistent with the role of HIF-1α stabilization in improving barrier function in UC patients and support the trends in clinical effects observed, including histologic endpoints. A Phase 2 study of GB004 in patients with mild-to-moderate UC (SHIFT-UC, NCT04556383) is currently ongoing. Sponsored by GB004, Inc., a wholly owned subsidiary of Gossamer Bio, Inc.

G-CSF as a suitable alternative to GM-CSF to boost dinutuximab-mediated neutrophil cytotoxicity in neuroblastoma treatment

BackgroundCurrent immunotherapy for patients with high-risk neuroblastoma involves the therapeutic antibody dinutuximab that targets GD2, a ganglioside expressed on the majority of neuroblastoma tumors. Opsonized tumor cells are killed through...