Complex role of neutrophils in the tumor microenvironment: an avenue for novel immunotherapies

Neutrophils,which originate from the bone marrow and are characterized by a segmented nucleus and a brief lifespan,have a crucial role in the body’s defense against infections and acute inflammation.Recent research has uncovered the complex roles of neutrophils as regulators in tumorigenesis,during which neutrophils exhibit a dualistic nature that promotes or inhibits tumor progression.This adaptability is pivotal within the tumor microenvironment(TME).In this review,we provide a comprehensive characterization of neutrophil plasticity and heterogeneity,aiming to illuminate current research findings and discuss potential therapeutic avenues.By delineating the intricate interplay of neutrophils in the TME,this review further underscores the urgent need to understand the dual functions of neutrophils with particular emphasis on the anti-tumor effects to facilitate the development of effective therapeutic strategies against cancer.

The Combined Effect of Lumenato and Ceramide in the Protection of Collagen Damage Induced by Neutrophils in Normal Human Dermal Fibroblasts

Introduction: Collagen is the primary structural protein fibroblasts produce in the skin’s extracellular matrix. Infiltration of neutrophils into the epidermis and dermis by exposure to UV causes collagen damage and contributes to photoaging. Methods: To study the combined effect of Lumenato and ceramide in preventing collagen-1 damage induced by phagocytes, we used co-cultures of normal human dermal fibroblasts (fibroblasts) and activated human neutrophils. The present study aimed to determine the protective effect of the combination of Lumenato and ceramide on fibroblast collagen-1 damage induced by neutrophils. Results: Lumenato (in the range of 6.5 - 208 μg/ml) or ceramide (in the range of 0.1 - 50 μM) inhibited the production of superoxides and MPO by TNFα-stimulated neutrophils, as well as the production of NO by LPS-stimulated macrophages in a dose-dependent manner. The combinations of Lumenato and ceramide, in low concentrations, caused synergistic prevention of fibroblasts’ collagen-1 damage induced by TNFα-activated neutrophils, detected by fluorescence immunostaining and WB analysis. MPO activity in the supernatants of the co-cultures was also synergistically inhibited. Adding Lumenato or ceramide singly or in combinations in these low concentrations to the fibroblast cultures did not affect the expression of collagen-1. The combinations of Lumenato or ceramide in these concentrations also caused a synergistic inhibition of NO production by activated macrophages. Conclusions: The results suggest that combining low concentrations of Lumenato and ceramide results in synergistic protection against fibroblasts’ collagen-1 damage induced by neutrophils, thus indicating their possible potential for enhanced skin health.

Cancer-educated neutrophils promote lung cancer progression via PARP-1-ALOX5-mediated MMP-9 expression

Objective:Neutrophils are one of the most predominant infiltrating leukocytes in lung cancer tissues and are associated with lung cancer progression.How neutrophils promote lung cancer progression,however,has not been established.Methods:Kaplan–Meier plotter online analysis and tissue immunohistochemistry were used to determine the relationship between neutrophils and overall survival in lung cancer patients.The effect of neutrophils on lung cancer was determined using the Transwell migration assay,a proliferation assay,and a murine tumor model.Gene knockdown was used to determine poly ADPribose polymerase(PARP)-1 function in lung cancer-educated neutrophils.Western blot analysis and gelatin zymography were used to demonstrate the correlation between PARP-1 and matrix metallopeptidase 9(MMP-9).Immunoprecipitation coupled to mass spectrometry(IP/MS)was used to identify the proteins interacting with PARP-1.Co-immunoprecipitation(Co-IP)was used to confirm that PARP-1 interacts with arachidonate 5-lipooxygenase(ALOX5).Neutrophil PARP-1 blockage by AG14361 rescued neutrophil-promoted lung cancer progression.Results:An increased number of infiltrating neutrophils was negatively associated with overall survival in lung cancer patients(P<0.001).Neutrophil activation promoted lung cancer cell invasion,migration,and proliferation in vitro,and murine lung cancer growth in vivo.Mechanistically,PARP-1 was shown to be involved in lung cancer cell-induced neutrophil activation to increase MMP-9 expression through interacting and stabilizing ALOX5 by post-translational protein modification(PARylation).Blocking PARP-1 by gene knockdown or AG14361 significantly decreased ALOX5 expression and MMP-9 production,and eliminated neutrophil-mediated lung cancer cell invasion and in vivo tumor growth.Conclusion:We identified a novel mechanism by which PARP-1 mediates lung cancer cell-induced neutrophil activation and PARylates ALOX5 to regulate MMP-9 expression,which exacerbates lung cancer progression.

Predictive value of tumor-infiltrating lymphocytes for neoadjuvant therapy response in triple-negative breast cancer: A systematic review and meta-analysis

BACKGROUND The association between tumor-infiltrating lymphocyte(TIL)levels and the res-ponse to neoadjuvant therapy(NAT)in patients with triple-negative breast cancer(TNBC)remains unclear.AIM To investigate the predictive potential of TIL levels for the response to NAT in TNBC patients.METHODS A systematic search of the National Center for Biotechnology Information PubMed database was performed to collect relevant published literature prior to August 31,2023.The correlation between TIL levels and the NAT pathologic com-plete response(pCR)in TNBC patients was assessed using a systematic review and meta-analysis.Subgroup analysis,sensitivity analysis,and publication bias analysis were also conducted.RESULTS A total of 32 studies were included in this meta-analysis.The overall meta-ana-lysis results indicated that the pCR rate after NAT treatment in TNBC patients in the high TIL subgroup was significantly greater than that in patients in the low TIL subgroup(48.0%vs 27.7%)(risk ratio 2.01;95%confidence interval 1.77-2.29;P<0.001,I2=56%).Subgroup analysis revealed that the between-study hetero-geneity originated from differences in study design,TIL level cutoffs,and study populations.Publication bias could have existed in the included studies.The meta-analysis based on different NAT protocols revealed that all TNBC patients with high levels of TILs had a greater rate of pCR after NAT treatment in all protocols(all P≤0.01),and there was no significant between-protocol difference in the statistics among the different NAT protocols(P=0.29).Additionally,sensitivity analysis demonstrated that the overall results of the meta-analysis remained consistent when the included studies were individually excluded.CONCLUSION TILs can serve as a predictor of the response to NAT treatment in TNBC patients.TNBC patients with high levels of TILs exhibit a greater NAT pCR rate than those with low levels of TILs,and this predictive capability is con-sistent across different NAT regimens.

FOXO1 reshapes neutrophils to aggravate acute brain damage and promote late depression after traumatic brain injury

Background:Neutrophils are traditionally viewed as first responders but have a short onset of action in response to traumatic brain injury(TBI).However,the heterogeneity,multifunctionality,and time-dependent modulation of brain damage and outcome mediated by neutrophils after TBI remain poorly understood.Methods:Using the combined single-cell transcriptomics,metabolomics,and proteomics analysis from TBI patients and the TBI mouse model,we investigate a novel neutrophil phenotype and its associated effects on TBI outcome by neurological deficit scoring and behavioral tests.We also characterized the underlying mechanisms both invitro and invivo through molecular simulations,signaling detections,gene expression regulation assessments[including dual-luciferase reporter and chromatin immunoprecipitation(ChIP)assays],primary cultures or co-cultures of neutrophils and oligodendrocytes,intracellular iron,and lipid hydroperoxide concentration measurements,as well as forkhead box protein O1(FOXO1)conditional knockout mice.Results:We identified that high expression of the FOXO1 protein was induced in neutrophils after TBI both in TBI patients and the TBI mouse model.Infiltration of these FOXO1high neutrophils in the brain was detected not only in the acute phase but also in the chronic phase post-TBI,aggravating acute brain inflammatory damage and promoting late TBI-induced depression.In the acute stage,FOXO1 upregulated cytoplasmic Versican(VCAN)to interact with the apoptosis regulator B-cell lymphoma-2(BCL-2)-associated X protein(BAX),suppressing the mitochondrial translocation of BAX,which mediated the antiapoptotic effect companied with enhancing interleukin-6(IL-6)production of FOXO1high neutrophils.In the chronic stage,the“FOXO1-transferrin receptor(TFRC)”mechanism contributes to FOXO1high neutrophil ferroptosis,disturbing the iron homeostasis of oligodendrocytes and inducing a reduction in myelin basic protein,which contributes to the progression of late depression after TBI.Conclusions:FOXO1high neutrophils represent a novel neutrophil phenotype that emerges in response to acute and chronic TBI,which provides insight into the heterogeneity,reprogramming activity,and versatility of neutrophils in TBI.

Tumor-infiltrating T-Lymphocyte immunity-related immune tolerance and anti–programmed cell death protein 1/ligand of programmed cell death protein 1 therapy for advanced hepatocellular carcinoma

Systemic therapy has become the standard treatment for patients with advanced hepatocellular carcinoma(HCC)whose treatment options are limited.However,the long-term patient response to drugs and the survival outcomes remain a concern.With increasing exploration of the HCC microenvironment,particularly in terms of T lymphocyte immunity,a new era of immunomolecular targeted therapy,based on molecular signaling,has arrived for advanced HCC.In the study of immune tolerance of the intrinsic HCC microenvironment,we found that multiple immunosuppressive mechanisms and immune checkpoint inhibitors,such as anti–programmed cell death protein 1/ligand of programmed cell death protein 1 therapy,have improved clinical outcomes in some patients with advanced HCC.Furthermore,various combination therapies have been investigated,and HCC types have been categorized into different types based on anti–programmed cell death protein 1(PD-1)/ligand of programmed cell death protein 1(PD-L1)treatment.In this paper,we first discuss the tumor-infiltrating T lymphocyte immunity and immune tolerance of HCC.We then clarify the basic mechanism of anti–PD-1/PD-L1 therapy and discuss the types of HCC based on anti–PD-1/PD-L1 therapy.Thereafter,we explain the relevant studies and mechanisms of combination therapy of anti–PD-1/PD-L1 with antiangiogenesis drugs or multikinase kinase inhibitors,anti–T lymphocyte–related signaling pathways in HCC,and other anti-CD8+T cell immune checkpoints.In this way,this review offers a deeper understanding of anti–PD-1/PD-L1 immunotherapy for advanced HCC,in order to provide better individualized treatments for patients with advanced HCC.

TREM-1 mediates interaction between substantia nigra microglia and peripheral neutrophils

Microglia-mediated neuroinflammation is considered a pathological feature of Parkinson's disease.Triggering receptor expressed on myeloid cell-1(TREM-1)can amplify the inherent immune response,and crucially,regulate inflammation.In this study,we found marked elevation of serum soluble TREM-1 in patients with Parkinson's disease that positively correlated with Parkinson's disease severity and dyskinesia.In a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease,we found that microglial TREM-1 expression also increased in the substantia nigra.Further,TREM-1 knockout alleviated dyskinesia in a mouse model of Parkinson's disease and reduced dopaminergic neuronal injury.Meanwhile,TREM-1 knockout attenuated the neuroinflammatory response,dopaminergic neuronal injury,and neutrophil migration.Next,we established an in vitro 1-methyl-4-phenyl-pyridine-induced BV2 microglia model of Parkinson's disease and treated the cells with the TREM-1 inhibitory peptide LP17.We found that LP17 treatment reduced apoptosis of dopaminergic neurons and neutrophil migration.Moreover,inhibition of neutrophil TREM-1 activation diminished dopaminergic neuronal apoptosis induced by lipopolysaccharide.TREM-1 can activate the downstream CARD9/NF-κB proinflammatory pathway via interaction with SYK.These findings suggest that TREM-1 may play a key role in mediating the damage to dopaminergic neurons in Parkinson's disease by regulating the interaction between microglia and peripheral neutrophils.

Effects of Berbamine on PAF Production in Human Neutrophils and on Platelet Aggregation

The effects of berbamine, an alkaloid of dibenzylisoquinoline, on PAF produc tion in human neutrophils and on platelet aggregation induced by PAF were studied and compared with those of the calcium antagonist verapamil. Preincubation with berbamine (50 mmol / L, 100 mmol / L) or verapamil (10 mmol / L, 100 mmol / L) was shown to significantly inhibit A 23187 stimulated PAF synthesis. Berbamine and verapamil were found to inhibit platelet aggregation induced by PAF 70 pmol / L in a dose dependent manner. These results suggest that the inhibitory effects of berbamine and verapamil on A 23187 stimulated PAF synthesis in human neutrophils and PAF induced platelet aggregation are possibly brought about by inhibiting cellular calcium influx.

Luteolin prevents f MLP-induced neutrophils adhesion via suppression of LFA-1 and phosphodiesterase 4 activity

Luteolin is an active ingredient found early from Fofium perillae and Flos Ionicerae, and has a specific inhibition on phosphodiesterase 4 （PDE4） activity in vitro. Researches show luteolin has pharmacological effects of anti-inflammation, anti-anaphylaxis, antitumor, antioxidant, protection of nervous system and so on, and has mainly been used for the treatment of respiratory inflammatory diseases, cancer and cardiovascular disease in clinic. PDE4, specific to hydrolyze cyclic AMP （cAMP）, is considered to be a new anti-inflammatory target due to the decisive role on cAMP signal in inflammatory cells such as neutrophils. In order to explore the anti-inflammatory mechanism, we further studied the effects of luteolin on the activity and expression of PDE4, the expression of lymphocyte function-associated antigen-1 （LFA-1） and macrophage-1 （MAC-l） in neutrophils, and the adhesion of neutrophils and endothelial cells. The results showed that luteolin had a dose-dependent inhibition on both bare PDE4 activity and PDE4 in cultured neutrophils, and had an obviously promotive effect on gene expressions of PDE4A, 4B and 4D in later period. Luteolin had a significant inhibitory effect on neutrophils adhesion and LFA-1 expression in early stage, and had no obvious effect on MAC-1 expression. Therefore, luteolin can inhibit LFA-1 expression of neutrophils, then inhibit the adhesion of neutrophils and endothelial cells, and the mechanism is at least related with the inhibition of PDE4 activity.

Influence of gallic acid on porcine neutrophils phosphodiesterase 4,IL-6,TNF-α and rat arthritis model

Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inhibition on c AMP-phosphodiesterase（PDE）. To explore the anti-inflammatory effect and mechanism, the influence of gallic acid on neutrophils PDE4 activity and expression, TNF-α and IL-6 content and rat arthritis model were further studied. PDE4 activity and gene express were calculated respectively by substrate c AMP change examined with HPLC and real-time RT-PCR. The concentration of IL-6 and TNF-α in supernatant were assayed by ELISA method. Model of rat arthritis was caused by complete Freund＇s adjuvant. Results showed that gallic acid had a dose-dependent restraint on PDE4 activity of neutrophils in vitro, promoted significantly PDE4 A expression（P〈0.01）, and had no influence on the expressions of PDE4 B and 4D. However, PDE4 C expression was not detected. Gallic acid could promote IL-6 release（P〈0.05）, and inhibit TNF-α release of neutrophils（P〈0.05）. The experiment in vivo showed that gallic acid had obvious restraint on local inflammation of animal model（P〈0.05）. Therefore, the anti-inflammatory effect of gallic acid may be mediated in part through an inhibition on PDE4 activity and further an increase of IL-6 and a decrease of TNF-α of neutrophils, and this effect seemed to have no relationship with PDE4 expression.

LAG-3 expression on tumor-infiltrating T cells in soft tissue sarcoma correlates with poor survival

Objective: To elucidate the role and prognostic significance of lymphocyte activation-gene-3(LAG-3) in soft tissue sarcoma(STS).Methods: The expression of LAG-3 in patient and matched normal blood samples was analyzed by flow cytometry. The localization and prognostic values of LAG-3^+ cells in 163 STS patients were analyzed by immunohistochemistry. In addition, the expression of tumor-infiltrating CD3^+ T, CD4^+ T, and CD8^+ T cells and their role in the prognosis of STS were evaluated by immunohistochemistry. The effect of LAG-3 blockade was evaluated in an immunocompetent MCA205 fibrosarcoma mouse model.Results: Peripheral CD8^+ and CD4^+ T cells from STS patients expressed higher levels of LAG-3 than those from healthy donors.LAG-3 expression in STS was significantly associated with a poor clinical outcome(P = 0.038) and was correlated with high pathological grade(P < 0.001), advanced tumor stage(P = 0.016). Additionally, LAG-3 expression was highly correlated with CD8^+ T-cell infiltration(r = 0.7034, P < 0.001). LAG-3 was expressed in murine tumor-infiltrating lymphocytes, and its blockade decreased tumor growth and enhanced secretion of interferon-gamma by CD8^+ and CD4^+ T cells.Conclusions: LAG-3 blockade may be a promising strategy to improve the effects of targeted therapy in STS.

Heterogeneity of neutrophils in cancer:one size does not fit all

Neutrophils play an essential role in the defense against bacterial infections and orchestrate both the innate and adaptive immune responses.With their abundant numbers,diverse function and short life span,these cells are at the forefront of immune responses,and have gained attention in recent years because of their presence in tumor sites.Neutrophil involvement pertains to tumor cells'ability to construct a suitable tumor microenvironment(TME)that accelerates their own growth and malignancy,by facilitating their interaction with surrounding cells through the circulatory and lymphatic systems,thereby influencing tumor development and progression.Studies have indicated both pro-and anti-tumor properties of infiltrating neutrophils.The TME can exploit neutrophil function,recruitment,and even production,thus resulting in pro-tumor properties of neutrophils,including promotion of genetic instability,tumor cell proliferation,angiogenesis and suppression of anti-tumor or inflammatory response.In contrast,neutrophils can mediate anti-tumor resistance by direct cytotoxicity to the tumor cells or by facilitating anti-tumor functions via crosstalk with T cells.Here,we summarize current knowledge regarding the effects of neutrophil heterogeneity under homeostatic and tumor conditions,including neutrophil phenotype and function,in cancer biology.

Clinical significance of tumor-infiltrating lymphocytes for gastric cancer in the era of immunology

Immunotherapy has begun to revolutionize cancer treatment, by introducing therapies that target the host immune system instead of the tumor, therapies that possess unique adverse event profiles, and therapies that may cure certain types of cancer. The immune microenvironment of tumors is emerging as the most important means of understanding the relationship between a patient' immune system and their cancer, informing prognosis, and guiding immunotherapy, such as an antibody blockade of immune checkpoints. For some solid tumors, simple quantitation of lymphocyte infiltration would seem to have prognostic significance, suggesting that lymphocyte infiltration is not passive but may actively promote or inhibit tumor growth. For gastric cancers, several studies have provided strong evidence that immune cells contribute to determining prognosis. However, the exact role of immune cells in gastric cancer remains unclear. Therefore, this review focuses on the clinical significance of immune cells, especially tumor-infiltrating lymphocytes, in gastric cancer.

Targeting and exploitation of tumor-associated neutrophils to enhance immunotherapy and drug delivery for cancer treatment

Neutrophils,the most abundant leukocytes in human blood,are essential fighter immune cells against microbial infection.Based on the finding that neutrophils can either restrict or promote cancer progression,tumor-associated neutrophils(TAN)are classified into anti-tumor N1 and pro-tumor N2 subsets.One of the major mechanisms underlying the tumor-promoting function of N2-TANs is suppression of adaptive immune cells,in particular,cytotoxic T lymphocytes.Currently,no established methodologies are available that can unequivocally distinguish immunosuppressive TANs and granulocytic/polymorphonuclear myeloid-derived suppressor cells(G/PMN-MDSC).In view of the critical role of PMN-MDSCs in immune evasion and resistance to cancer immunotherapy,as established from data obtained with diverse cancer models,therapeutic strategies targeting these cells have been actively developed to enhance the efficacy of immunotherapy.Here,we have reviewed the available literature on strategies targeting PMN-MDSCs and summarized the findings into four categories:(1)depletion of existing PMN-MDSCs,(2)blockade of the development of PMNMDSCs,(3)blockade of PMN-MDSC recruitment,(4)inhibition of immunosuppressive function.Owing to their high mobility to inflamed organs and ability to trespass the blood-brain barrier,neutrophils are outstanding candidate carriers in nanoparticle-based therapies.Another attractive application of neutrophils in cancer therapy is the use of neutrophil membrane-derived nanovesicles as a surrogate of extracellular vesicles for more efficient and scalable drug delivery.In the second part of the review,we have highlighted recent advances in the field of neutrophil-based cancer drug delivery.Overall,we believe that neutrophil-based therapeutics are a rapidly growing area of cancer therapy with significant potential benefits.

RO-heparin Inhibits L-Selectin-mediated Neutrophils Adhesion to Vascular Endothelium Under Flow Conditions

Selectins are carbohydrate-binding cell adhesion molecules that play a major role in the initiation of inflammatory responses. Accumulaed evidence has suggested that heparin＇s anti-inflammatory effects are mainly mediated by blocking L-or P-selectin-initiated cell adhesion. Recently, we have reported that periodate-oxidized, borohydridereduced heparin （RO-heparln） can inhibit P-selectin-mediated acute inflammation. Here we further examined the effect of RO-heparin on the adhesion of L-selectin-mediated leukocytes to vascular endothelium under flow conditions in vivo and in vitro. The results show that RO-heparin with a low anticoagulant activity can effectively reduce leucocyte roiling on thioglycoUate-induced rat mesenterlc venules and L-selectin-metadiated neutrophil roiling on TNF-α-induced human umbilical vein endothelial cells（HUVECs） under flow conditions. Our findings suggest that the effect of RO-heparin on inflammatory responses is mainly a result of its inhibiting the interaction between P- or L-selectin and its ligands. The findings also suggest that RO-heparin may be useful in preventing inflammation diseases.

Phagocytic and oxidative burst activity of neutrophils in the end stage of liver cirrhosis

AIM：To evaluate the phagocytic activity and neutrophil oxidative burst in liver cirrhosis.METHODS： In 45 patients with advanced postalcoholic liver cirrhosis （aged 45±14 years） and in 25 healthy volunteers （aged 38±5 years）, the percentage of phagocytizing cells after in vitro incubation with E. coli （Phagotest Kit）, phagocytic activity （mean intensity of fluorescence, MIF） and the percentage of neutrophil oxidative burst （Bursttest Kit）, and the level of free oxygen radical production （MIF of Rodamine 123） were analyzed by flow cytometry. The levels of soluble sICAM-1, sVCAM-1, sP-selectin, sE-selectin, sL-selectin, and TNF-α were determined in blood serum.RESISTS： The percentage of E. coli phagocytizing neutrophils in liver cirrhosis patients was comparable to that in healthy subjects. MIF of neutrophil - ingested E. coli was higher in patients with liver cirrhosis. The oxidative burst in E. coli phagocytizing neutrophils generated less amount of active oxygen compounds in liver cirrhosis pa- tients （MIF of R123：24.7±7.1 and 29.7±6.6 in healthy, P〈0.01）. Phorbol myristate acetate （PMA） - stimulated neutrophilsproduced less reactive oxidants in liver cirrhosis patients than in healthy subjects （MIF of R123： 42.7±14.6 vs 50.2±13.3, P〈0.01）. A negative correlation was observed between oxidative burst MIF of PMA-stimulated neutrophils and ALT and AST levels （r -0.35, P〈0.05; r-0.4, P〈0.03）. sVCAM-1, sICAM-1, sE-selectin concentrations correlated negatively with the oxygen free radical production （MIF of R123） in neutrophils after PMA stimulation in liver cirrhosis patients （r-0.45, P〈0.05, r-0.41, P〈0.05; r-0.39, P〈0.05, respectively）.CONCLUSION： Neutrophil metabolic activity diminishes together with the intensification of liver failure. The metabolic potential of phagocytizing neutrophils is significantly lower in liver cirrhosis patients, which can be one of the causes of immune mechanism damage. The evaluation of oxygen metabolism of E. coli-stimulated neutrophils reveals that the amount of released oxygen metabolites is smaller in liver cirrhosis patients than in healthy subjects.

Characteristics of Neutrophils Infiltration in Ventilation-induced Lung Injury

Neutrophils play a critical role in ventilation-induced lung injury. This study was aimed to investigate the characteristics of neutrophils influx in lungs induced by high tidal volume ventilation. Anaesthetized rats were randomly divided into low tidal volume ventilation group (Vt: 7 mL/kg, LV group) or high tidal volume ventilation group (Vt:42mL/kg, HV group ) (n=40 in each). Rats in each group were ventilated for 0, 60, 90, 120 and 240 min. The wet/dry lung weight ratio (W/D) was measured. The levels of macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor-α (TNF-α), and the activity of myeloperoxidase (MPO) were detected by enzyme-linked immunosorbent assay (ELISA). The number of neutrophils in bronchoalveolar lavage fluid (BALF) was counted after Wright’s staining, and the percentage of netrophils in lung tissues calculated. Histopatholgical examination was used to observe the changes of lung tissues after different ventilations. The results showed that the W/D weight ratio was increased, and the levels of MIP-2 and TNF-α significantly enhanced in HV group at 90, 120 and 240 min. Neutrophils in BALF and the neutrophil percentage in lung tissues were also elevated at 120 and 240 min, which coincided with the enhanced activity of MPO in HV group. The lung injury was significantly related with the ventilation time and the infiltration of neutrophils in lungs in HV group. In conclusion, in ventilation-induced lung injury, neutrophil infiltration is present in a time-dependent manner and associated with the aggravated lung injury. Pulmonary structural damage may be the main reason for ventilation-induced lung injury.

Contribution of neutrophils in the pathogenesis of rheumatoid arthritis

Neutrophils are major innate immune effector cells for host defense and have been a topic of active research for their participation in the pathogenesis of autoimmune inflammatory diseases including rheumatoid arthritis(RA)due to recently discovered neutrophil extracellular trap(NET) formation. NET formation and other mechanisms leading to the release of neutrophil nuclear and cytoplasmic contents are implicated as a source of citrullinated antigens in RA. Further investigations are required to delineate what factors diverge neutrophils from host defense to autoimmune response in RA.

Association between Up-regulation of Fas Ligand Expression and Apoptosis of Tumor-infiltrating Lymphocytes in Human Breast Cancer

In order to study the significance of FasL expression in immune escape of breast cancer, FasL protein expression and the number of tumor-infiltrating lymphocytes （TILs） in 40 specimens of breast cancer were detected by immunohistochemitry. The expression of FasL mRNA was measured by in situ hybridization in the consecutive tissue slices of 40 breast cancers respectively. By using terminal deoxynucleotidyl transferase-mediaed dUTP nick end labeling （TUNEL）, apoptotic cells were detected in 40 specimens of breast cancer. The expression of FasL was detected in all 40 specimens to varying degrees. In the consecutive tissue slices, the location of expression of FasL protein corresponded with that of FasL mRNA. In those with FasL extensive expression, the number of TILs was less （P〈0.05）, the apoptotic index （AI） of TILs was higher and the AI of tumor cells was lower （P〈0.01） than those with FasL weak expression respectively. The AI of TILs was correlated with that of tumor cells （r=-0.629, P〈0.01）. In conclusion, breast cancer cells can induce the apoptosis of TILs through the expression of FasL, which can counterattack the immune system. This may be a mechanism of immune evasion in breast cancer.

Dipyridamole enhances inhibitory effect of adenosine on neutrophils in human peripheral blood

Objective： It was known that neutrophils play an important role in ischemic-reperfusion injury. In this study we tested the effect and its mechanism of dipyfidamole on neutrophils. Methods：Hydrogen peroxide（H2O2） production by neutrophils was determined using luminol amplified chemiluminescence and the percentage of activity was calculated by observing the uninhibited peak height. Results： Dipyfidamole per se produced a concentration-dependent inhibition of H2O2 by formyl-MetleuPhe（fMLP）-stimulated neutrophils. Dipyridamole at a low concentration（0.3 μ mol · L^-1） that per se affected neutrophils only slightly, enhanced markedly the effects of adenosine on neutrophils. On the other hand, dipyfidamole did not alter the inhibitory effect of NECA（5＇ -N-ethylcarboxamidoadenosine） on neutrophils. However, propentofylline, a known inhibitor of adenosine uptake, also gotten the same result. Conclusion：Dipyfidamole inhibited the production of H2O2 by fMLP-sfimulated neutrophils. Dipyfidamole at a low concentration enhanced the inhibitory effect of adenosine on neutrophils. The mechanism involved is probably due to the effect of dipyfidamole on adenosine uptake.