Biological Roles of Neutrophil-Derived Granule Proteins and Cytokines

Tumour-associated neutrophils: Potential therapeutic targets in pancreatic cancer immunotherapy

Pancreatic cancer (PC) is a highly malignant tumour of the digestive system with poor therapeutic response and low survival rates. Immunotherapy has rapidly developed in recent years and has achieved significant outcomes in numerous malignant neoplasms. However, responses to immunotherapy in PC are rare, and the immunosuppressive and desmoplastic tumour microenvironment (TME) significantly hinders their efficacy in PC. Tumour-associated neutrophils (TANs) play a crucial role in the PC microenvironment and exert a profound influence on PC immunotherapy by establishing a robust stromal shelter and restraining immune cells to assist PC cells in immune escape, which may subvert the current status of PC immunotherapy. The present review aims to offer a comprehensive summary of the latest progress in understanding the involvement of TANs in PC desmoplastic and immunosuppressive functions and to emphasise the potential therapeutic implications of focusing on TANs in the immunotherapy of this deleterious disease. Finally, we provide an outlook for the future use of TANs in PC immunotherapy.

Impaired neutrophil migration underpins host susceptibility to infectious colitis

Citrobacter rodentium models infection with enteropathogenic E. coli and ulcerative colitis (UC). While C57BL/6 (C57) mice recover, C3H/HeN (C3H) mice succumb to infection, partially due to increased colonic neutrophil elastase activity, also seen in UC patients; however, the underlying cause was unknown. Here we found that bone marrow, blood and colonic C57 neutrophils expressed CD11bHi and reached the infected colonic lumen where they underwent productive NETosis. In contrast, while the number of C3H neutrophils increased in the bone marrow, blood, and colon, they remained CD11bLo and got trapped in the submucosa, away from C. rodentium, where they underwent harmful NETosis. CD11bLo neutrophils in C3H mice infected with CRi9, which triggers expression of neutrophil chemoattractants, reached the colonisation site resulting in host survival. UC patient neutrophils also displayed decreased levels of the activation/differentiation markers CD16/CXCR4. These results, suggesting that neutrophil malfunction contributes to exacerbated colitis, provide insight for future therapeutic prospects.

Pathogenesis and interaction of neutrophils and extracellular vesicles in noncancer liver diseases

Liver disease ranks as the eleventh leading cause of mortality, leading to approximately 2 million deaths annually worldwide. Neutrophils are a type of immune cell that are abundant in peripheral blood and play a vital role in innate immunity by quickly reaching the site of liver injury. They exert their influence on liver diseases through autocrine, paracrine, and immunomodulatory mechanisms. Extracellular vesicles, phospholipid bilayer vesicles, transport a variety of substances, such as proteins, nucleic acids, lipids, and pathogenic factors, for intercellular communication. They regulate cell communication and perform their functions by delivering biological information. Current research has revealed the involvement of the interaction between neutrophils and extracellular vesicles in the pathogenesis of liver disease. Moreover, more research has focused on targeting neutrophils as a therapeutic strategy to attenuate disease progression. Therefore, this article summarizes the roles of neutrophils, extracellular vesicles, and their interactions in noncancerous liver diseases.

No Evidence of Neutrophil Response Modulation in Goats after Immunization against Paratuberculosis with a Heat-Inactivated Vaccine

Neutrophils are believed to play a role in the initial stages of paratuberculosis, and it has recently been demonstrated that vaccination can modulate their function via priming or through epigenetic and metabolic reprogramming (training). Modulation of the neutrophil response against Mycobacterium avium subspecies paratuberculosis (Map) through vaccination has been demonstrated in a rabbit model but not in ruminants. Therefore, in the present work, the effect of vaccination on the response of caprine neutrophils against Map was studied. Neutrophils were isolated from non-vaccinated (n = 7) and Gudair®-vaccinated goat kids (n = 7), before vaccination and 30 days post-vaccination. Then, several neutrophil functions were quantified ex vivo: cell-free and anchored neutrophil extracellular trap (NET) release, phagocytosis, and the differential expression of several cytokines and TLR2. The induction of cell-free NETosis and TLR2 expression by Map is reported for the first time. However, vaccination showed no significant effect on any of the functions studied. This suggests that the protection conferred by Gudair® vaccination is based on mechanisms that are independent of the neutrophil function modulation. Further research into the impact of alternative vaccination strategies or the paratuberculosis infection stage on ruminant neutrophil function could provide valuable insights into its role in paratuberculosis.

The different impact of drug-resistant Leishmania on the transcription programs activated in neutrophils

Drug resistance threatens the effective control of infections, including parasitic diseases such as leishmaniases. Neutrophils are essential players in antimicrobial control, but their role in drug-resistant infections is poorly understood. Here, we evaluated human neutrophil response to clinical parasite strains having distinct natural drug susceptibility. We found that Leishmania antimony drug resistance significantly altered the expression of neutrophil genes, some of them transcribed by specific neutrophil subsets. Infection with drug-resistant parasites increased the expression of detoxification pathways and reduced the production of cytokines. Among these, the chemokine CCL3 was predominantly impacted, which resulted in an impaired ability of neutrophils to attract myeloid cells. Moreover, decreased myeloid recruitment when CCL3 levels are reduced was confirmed by blocking CCL3 in a mouse model. Collectively, these findings reveal that the interplay between naturally drug-resistant parasites and neutrophils modulates the infected skin immune microenvironment, revealing a key role of neutrophils in drug resistance.

Macrophage and Neutrophil Dysregulation in Diabetic Wounds

SIGNIFICANCE

The incidence of diabetes continues to rise throughout the world in an alarming rate. Diabetic patients often develop diabetic foot ulcers (DFUs), many of which do not heal. Non-healing DFUs are a major cause of hospitalization, amputation, and increased morbidity. Understanding the underlying mechanisms of impaired healing in DFU is crucial for its management.

RECENT ADVANCES

This review focuses on the recent advancements in macrophage and neutrophils in diabetic wounds and DFUs. In particular, we will discuss diabetes-induced dysregulations and dysfunctions of macrophage and neutrophil functions.

CRITICAL ISSUES

It is well established that diabetic wounds are characterized by stalled inflammation that results in impaired healing. Recent findings in the field suggest that dysregulation of macrophages and neutrophils play a critical role in impaired healing in DFUs. The delineation of mechanisms that restore macrophage and neutrophil function in diabetic wound healing is the focus of intense investigation.

FUTURE DIRECTIONS

The breadth of recently generated knowledge on the activity of macrophages and neutrophils in diabetic wound healing is impressive. Experimental models have delineated pathways that hold promise for the treatment of diabetic wounds and DFUs. These pathways may be useful targets for further clinical investigation.

Single-cell transcriptome analysis reveals heterogeneity of neutrophils in non-small cell lung cancer

BACKGROUND

Lung cancer stands out as a highly perilous malignant tumor with severe implications for human health. There has been a growing interest in neutrophils as a result of their role in promoting cancer in recent years. Thus, the present study aimed to investigate the heterogeneity of neutrophils in non-small cell lung cancer (NSCLC).

METHODS

Single-cell RNA sequencing of tumor-associated neutrophils (TANs) and polymorphonuclear neutrophils sourced from the Gene Expression Omnibus database was analyzed. Moreover, cell-cell communication, differentiation trajectories and transcription factor analyses were performed.

RESULTS

Neutrophils were found to be closely associated with macrophages. Four major types of TANs were identified: a transitional subcluster that migrated from blood to tumor microenvironment (TAN-0), an inflammatory subcluster (TAN-1), a subpopulation that displayed a distinctive transcriptional signature (TAN-2) and a final differentiation state that promoted tumor formation (TAN-3). Meanwhile, TAN-3 displayed a marked increase in glycolytic activity. Finally, transcription factors were analyzed to uncover distinct TAN cluster-specific regulons.

CONCLUSIONS

The discovery of the dynamic characteristics of TANs in the present study is anticipated to contribute to yielding a better understanding of the tumor microenvironment and advancing the treatment of NSCLC.

Matrix metalloproteinases are associated with severity of disease among COVID-19 patients: A possible pharmacological target

COVID-19 is a devastating disease and imbalanced matrix metalloproteinase (MMP) activity may contribute to its pathophysiology. This exploratory study examined whether increased circulating concentrations of MMP-2 and MMP-9, and their endogenous inhibitors, the tissue inhibitors of MMP (TIMP)-1, TIMP-2, TIMP-3 and TIMP-4 are persistently found in patients 2 weeks after their recovery from severe or critical COVID-19 as compared with those in healthy controls. Subjects who had severe (n = 26) or critical (n = 25) PCR-confirmed COVID-19 and healthy controls (n = 21) had blood samples drawn 2 weeks after recovery and serum MMP-2, MMP-9, TIMP-1, TIMP-2, TIMP-3 and TIMP-4 were determined using two Human Luminex® Discovery Assays. Circulating MMP activity was also determined by gel zymography. Patients who had severe or critical COVID-19 had increased circulating MMP-9 and MMP-2 concentrations, with increased MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios indicating increased MMP activity, confirmed by gel zymography (all p < 0.05). Higher circulating MMP-9 (but not MMP-2) concentrations were found in critical versus severe COVID-19 (p < 0.05). We found increased circulating MMP-9 and MMP-2 concentrations and activity many days after recovery from the acute disease, with MMP-9 levels associated with disease severity. These biochemical alterations suggest that MMP-2 and MMP-9 may be important pharmacological targets in COVID-19.

Immune cells in skin inflammation, wound healing, and skin cancer

Given the self-evident importance of cutaneous immunity in the maintenance of body-surface homeostasis, disturbance of the steady-state skin is inextricably intertwined with dysfunction in cutaneous immunity. It is often overlooked by people that skin, well-known as a solid physical barrier, is also a strong immunological barrier, considering the abundant presence of immune cells including lymphocytes, granulocytes, dendritic cells, and macrophages. What's more, humoral immune components including cytokines, immunoglobulins, and antimicrobial peptides are also rich in the skin. This review centers on skin inflammation (acute and chronic, infection and aseptic inflammation), wound healing, and skin cancer to elucidate the elaborate network of immune cells in skin diseases.

Detection and characterization of copy number variation in three differentially-selected Nellore cattle populations

Introduction: Nellore cattle (Bos taurus indicus) is the main beef cattle breed raised in Brazil. This breed is well adapted to tropical conditions and, more recently, has experienced intensive genetic selection for multiple performance traits. Over the past 43 years, an experimental breeding program has been developed in the Institute of Animal Science (IZ, Sertaozinho, SP, Brazil), which resulted in three differentially-selected lines known as Nellore Control (NeC), Nellore Selection (NeS), and Nellore Traditional (NeT). The primary goal of this selection experiment was to determine the response to selection for yearling weight (YW) and residual feed intake (RFI) on Nellore cattle. The main objectives of this study were to: 1) identify copy number variation (CNVs) in Nellore cattle from three selection lines; 2) identify and characterize CNV regions (CNVR) on these three lines; and 3) perform functional enrichment analyses of the CNVR identified. Results: A total of 14,914 unique CNVs and 1,884 CNVRs were identified when considering all lines as a single population. The CNVRs were non-uniformly distributed across the chromosomes of the three selection lines included in the study. The NeT line had the highest number of CNVRs (n = 1,493), followed by the NeS (n = 823) and NeC (n = 482) lines. The CNVRs covered 23,449,890 bp (0.94%), 40,175,556 bp (1.61%), and 63,212,273 bp (2.54%) of the genome of the NeC, NeS, and NeT lines, respectively. Two CNVRs were commonly identified between the three lines, and six, two, and four exclusive regions were identified for NeC, NeS, and NeT, respectively. All the exclusive regions overlap with important genes, such as SMARCD3, SLC15A1, and MAPK1. Key biological processes associated with the candidate genes were identified, including pathways related to growth and metabolism. Conclusion: This study revealed large variability in CNVs and CNVRs across three Nellore lines differentially selected for YW and RFI. Gene annotation and gene ontology analyses of the exclusive CNVRs to each line revealed specific genes and biological processes involved in the expression of growth and feed efficiency traits. These findings contribute to the understanding of the genetic mechanisms underlying the phenotypic differences among the three Nellore selection lines.

Activation of leukotriene B4 receptor 1 is a prerequisite for complement receptor 3-mediated antifungal responses of neutrophils

Invasive fungal infections are life-threatening, and neutrophils are vital cells of the innate immune system that defend against them. The role of LTA4H-LTB4-BLT1 axis in regulation of neutrophil responses to fungal infection remains poorly understood. Here, we demonstrated that the LTA4H-LTB4-BLT1 axis protects the host against Candida albicans and Aspergillus fumigatus, but not Cryptococcus neoformans infection, by regulating the antifungal activity of neutrophils. Our results show that deleting Lta4h or Blt1 substantially impairs the fungal-specific phagocytic capacity of neutrophils. Moreover, defective activation of the spleen tyrosine kinase (Syk) and extracellular signal-related kinase (ERK1/2) pathways in neutrophils accompanies this impairment. Mechanistically, BLT1 regulates CR3-mediated, β-1,3-glucan-induced neutrophil phagocytosis, while a physical interaction with CR3 with slight influence on its dynamics is observed. Our findings thus demonstrate that the LTA4H-LTB4-BLT1 axis is essential for the phagocytic function of neutrophils in host antifungal immune response against Candida albicans and Aspergillus fumigatus.

Biomaterials Functionalized with Inflammasome Inhibitors-Premises and Perspectives

This review aimed at searching literature for data regarding the inflammasomes' involvement in the pathogenesis of oral diseases (mainly periodontitis) and general pathologies, including approaches to control inflammasome-related pathogenic mechanisms. The inflammasomes are part of the innate immune response that activates inflammatory caspases by canonical and noncanonical pathways, to control the activity of Gasdermin D. Once an inflammasome is activated, pro-inflammatory cytokines, such as interleukins, are released. Thus, inflammasomes are involved in inflammatory, autoimmune and autoinflammatory diseases. The review also investigated novel therapies based on the use of phytochemicals and pharmaceutical substances for inhibiting inflammasome activity. Pharmaceutical substances can control the inflammasomes by three mechanisms: inhibiting the intracellular signaling pathways (Allopurinol and SS-31), blocking inflammasome components (VX-765, Emricasan and VX-740), and inhibiting cytokines mediated by the inflammasomes (Canakinumab, Anakinra and Rilonacept). Moreover, phytochemicals inhibit the inflammasomes by neutralizing reactive oxygen species. Biomaterials functionalized by the adsorption of therapeutic agents onto different nanomaterials could represent future research directions to facilitate multimodal and sequential treatment in oral pathologies.

A neutrophil extracellular trap-related risk score predicts prognosis and characterizes the tumor microenvironment in multiple myeloma

Multiple myeloma (MM) is a distinguished hematologic malignancy, with existing studies elucidating its interaction with neutrophil extracellular traps (NETs), which may potentially facilitate tumor growth. However, systematic investigations into the role of NETs in MM remain limited. Utilizing the single-cell dataset GSE223060, we discerned active NET cell subgroups, namely neutrophils, monocytes, and macrophages. A transcriptional trajectory was subsequently constructed to comprehend the progression of MM. Following this, an analysis of cellular communication in MM was conducted with a particular emphasis on neutrophils, revealing an augmentation in interactions albeit with diminished strength, alongside abnormal communication links between neutrophils and NK cells within MM samples. Through the intersection of differentially expressed genes (DEGs) between NET active/inactive cells and MM versus healthy samples, a total of 316 genes were identified. This led to the development of a 13-gene risk model for prognostic prediction based on overall survival, utilizing transcriptomics dataset GSE136337. The high-risk group manifested altered immune infiltration and heightened sensitivity to chemotherapy. A constructed nomogram for predicting survival probabilities demonstrated encouraging AUCs for 1, 3, and 5-year survival predictions. Collectively, our findings unveil a novel NET-related prognostic signature for MM, thereby providing a potential avenue for therapeutic exploration.

Neutrophils in Physiology and Pathology

Infections, cardiovascular disease, and cancer are major causes of disease and death worldwide. Neutrophils are inescapably associated with each of these health concerns, by either protecting from, instigating, or aggravating their impact on the host. However, each of these disorders has a very different etiology, and understanding how neutrophils contribute to each of them requires understanding the intricacies of this immune cell type, including their immune and nonimmune contributions to physiology and pathology. Here, we review some of these intricacies, from basic concepts in neutrophil biology, such as their production and acquisition of functional diversity, to the variety of mechanisms by which they contribute to preventing or aggravating infections, cardiovascular events, and cancer. We also review poorly explored aspects of how neutrophils promote health by favoring tissue repair and discuss how discoveries about their basic biology inform the development of new therapeutic strategies.

miRNA-132-5p mediates a negative feedback regulation of IL-8 secretion through S100A8/A9 downregulation in neutrophil-like HL-60 cells

Background

Neutrophils are an important source of pro-inflammatory and immunomodulatory cytokines. This makes neutrophils efficient drivers of interactions with immune and non-immune cells to maintain homeostasis and modulate the inflammatory process by notably regulating the release of cytokines. Ca2+-dependent regulatory mechanism encompassing cytokine secretion by neutrophils are not still identified. In this context, we propose to define new insights on the role of Ca2+-binding proteins S100A8/A9 and on the regulatory role of miRNA-132-5p, which was identified as a regulator of S100A8/A9 expression, on IL-8 secretion.

Methods

Differentiated HL-60 cells, a human promyelocytic leukemia cell line that can be induced to differentiate into neutrophil-like cells, were used as a model of human neutrophils and treated with N- formyl-methionyl-leucyl-phenylalanine (fMLF), a bacterial peptide that activates neutrophils. shRNA knockdown was used to define the role of selected targets (S100A8/A9 and miRNA-132-5p) on IL-8 secretion.

Results and discussion

Different types of cytokines engage different signaling pathways in the secretion process. IL-8 release is tightly regulated by Ca2+ binding proteins S100A8/A9. miRNA-132-5p is up-regulated over time upon fMLF stimulation and decreases S100A8/A9 expression and IL-8 secretion.

Conclusion

These findings reveal a novel regulatory loop involving S100A8/A9 and miRNA-132-5p that modulates IL-8 secretion by neutrophils in inflammatory conditions. This loop could be a potential target for therapeutic intervention in inflammatory diseases.

A metabolic perspective of the neutrophil life cycle: new avenues in immunometabolism

Neutrophils are the most abundant innate immune cells. Multiple mechanisms allow them to engage a wide range of metabolic pathways for biosynthesis and bioenergetics for mediating biological processes such as development in the bone marrow and antimicrobial activity such as ROS production and NET formation, inflammation and tissue repair. We first discuss recent work on neutrophil development and functions and the metabolic processes to regulate granulopoiesis, neutrophil migration and trafficking as well as effector functions. We then discuss metabolic syndromes with impaired neutrophil functions that are influenced by genetic and environmental factors of nutrient availability and usage. Here, we particularly focus on the role of specific macronutrients, such as glucose, fatty acids, and protein, as well as micronutrients such as vitamin B3, in regulating neutrophil biology and how this regulation impacts host health. A special section of this review primarily discusses that the ways nutrient deficiencies could impact neutrophil biology and increase infection susceptibility. We emphasize biochemical approaches to explore neutrophil metabolism in relation to development and functions. Lastly, we discuss opportunities and challenges to neutrophil-centered therapeutic approaches in immune-driven diseases and highlight unanswered questions to guide future discoveries.

Integrating network pharmacology and transcriptomic omics reveals that akebia saponin D attenuates neutrophil extracellular traps-induced neuroinflammation via NTSR1/PKAc/PAD4 pathway after intracerebral hemorrhage

Neutrophils and their production of neutrophil extracellular traps (NETs) significantly contribute to neuroinflammation and brain damage after intracerebral hemorrhage (ICH). Although Akebia saponin D (ASD) demonstrates strong anti-inflammatory activities and blood-brain barrier permeability, its role in regulating NETs formation and neuroinflammation following ICH is uncharted. Our research focused on unraveling the influence of ASD on neuroinflammation mediated by NETs and the mechanisms involved. We found that increased levels of peripheral blood neutrophils post-ICH are correlated with worse prognostic outcomes. Through network pharmacology, we identified ASD as a promising therapeutic target for ICH. ASD administration significantly improved neurobehavioral performance and decreased NETs production in neutrophils. Furthermore, ASD was shown to upregulate the membrane protein NTSR1 and activate the cAMP signaling pathway, confirmed through transcriptome sequencing, western blot, and immunofluorescence. Interestingly, the NTSR1 inhibitor SR48692 significantly nullified ASD's anti-NETs effects and dampened cAMP pathway activation. Mechanistically, suppression of PKAc via H89 negated ASD's anti-NETs effects but did not affect NTSR1. Our study suggests that ASD may reduce NETs formation and neuroinflammation, potentially involving the NTSR1/PKAc/PAD4 pathway post-ICH, underlining the potential of ASD in mitigating neuroinflammation through its anti-NETs properties.

Human and mouse neutrophils share core transcriptional programs in both homeostatic and inflamed contexts

Neutrophils are frequently studied in mouse models, but the extent to which findings translate to humans remains poorly defined. In an integrative analysis of 11 mouse and 13 human datasets, we find a strong correlation of neutrophil gene expression across species. In inflammation, neutrophils display substantial transcriptional diversity but share a core inflammation program. This program includes genes encoding IL-1 family members, CD14, IL-4R, CD69, and PD-L1. Chromatin accessibility of core inflammation genes increases in blood compared to bone marrow and further in tissue. Transcription factor enrichment analysis implicates members of the NF-κB family and AP-1 complex as important drivers, and HoxB8 neutrophils with JunB knockout show a reduced expression of core inflammation genes in resting and activated cells. In independent single-cell validation data, neutrophil activation by type I or type II interferon, G-CSF, and E. coli leads to upregulation in core inflammation genes. In COVID-19 patients, higher expression of core inflammation genes in neutrophils is associated with more severe disease. In vitro treatment with GM-CSF, LPS, and type II interferon induces surface protein upregulation of core inflammation members. Together, we demonstrate transcriptional conservation in neutrophils in homeostasis and identify a core inflammation program shared across heterogeneous inflammatory conditions.

Beyond the horizon: Neutrophils leading the way in the evolution of immunotherapy

Cancer is a complex and dynamic disease, initiated by a multitude of intrinsic mutations and progressed with the assistance of the tissue microenvironment, encompassed by stromal cells including immune cell infiltration. The novel finding that tumors can evade anti-cancer immune functions shaped the field of immunotherapy, which has been a revolutionary approach for the treatment of cancers. However, the development of predominantly T cell-targeted immunotherapy approaches, such as immune checkpoint inhibition, also brought about an accumulation of evidence demonstrating other immune cell drivers of tumor progression, such as innate immune cells and notably, neutrophils. In the past decade, neutrophils have emerged to be primary mediators of multiple cancer types and even in recent years, are gaining attention for their potential use in the next generation of immunotherapies. Here, we review current immunotherapy strategies and thoroughly discuss the roles of neutrophils in cancer and novel neutrophil-targeted methods for treating cancer.

Recent advances in the role of neutrophils and neutrophil extracellular traps in acute pancreatitis

Pancreatitis is an inflammatory disease, which is triggered by adverse events in acinar cells of the pancreas. After the initial injury, infiltration of neutrophils in pancreas is observed. In the initial stages of pancreatitis, the inflammation is sterile. It has been shown that the presence of neutrophils at the injury site can modulate the disease. Their depletion in experimental animal models of the acute pancreatitis has been shown to be protective. But information on mechanism of contribution to inflammation by neutrophils at the injury site is not clear. Once at injury site, activated neutrophils release azurophilic granules containing proteolytic enzymes and generate hypochlorous acid which is a strong microbicidal agent. Additionally, emerging evidence shows that neutrophil extracellular traps (NETs) are formed which consist of decondensed DNA decorated with histones, proteases and granular and cytosolic proteins. NETs are considered mechanical traps for microbes, but there is preliminary evidence to indicate that NETs, which constitute a special mechanism of the neutrophil defence system, play an adverse role in pancreatitis by contributing to the pancreatic inflammation and distant organ injury. This review presents the overall current information about neutrophils and their role including NETs in acute pancreatitis (AP). It also highlights current gaps in knowledge which should be explored to fully elucidate the role of neutrophils in AP and for therapeutic gains.

Type 17 mucosal-associated invariant T cells contribute to neutrophilic inflammation in patients with nasal polyps

BACKGROUND

Immune regulation in chronic rhinosinusitis with nasal polyps (CRSwNP) with a neutrophilic endotype remains unclear. Mucosal-associated invariant T (MAIT) cells are tissue-resident innate T lymphocytes that respond quickly to pathogens and promote chronic mucosal inflammation.

OBJECTIVE

We aimed to investigate the roles of MAIT cells in neutrophilic CRSwNP.

METHODS

Nasal tissues were obtained from 113 patients with CRSwNP and 29 control subjects. Peripheral and tissue MAIT cells and their subsets were analyzed by flow cytometry. Polyp-derived MAIT cells were analyzed by RNA sequencing to study their effects on neutrophils.

RESULTS

Endotypes of CRSwNP were classified as paucigranulocytic (n = 21), eosinophilic (n = 29), neutrophilic (n = 39), and mixed granulocytic (n = 24). Frequencies of MAIT cells were significantly higher in neutrophilic (3.62%) and mixed granulocytic (3.60%) polyps than in control mucosa (1.78%). MAIT cell percentages positively correlated with local neutrophil counts. MAIT cells were more enriched in tissues than in matched PBMCs. The frequencies of MAIT1 subset or IFN-γ+ MAIT cells were comparable among control tissues and CRSwNP subtypes. The proportions of MAIT17 subset or IL-17A+ MAIT cells were significantly increased in neutrophilic or mixed granulocytic polyps compared with controls. RNA sequencing revealed type 17 and pro-neutrophil profiles in neutrophilic polyp-derived MAIT cells. In patients with neutrophilic CRSwNP, the proportions of MAIT and MAIT17 cells were positively correlated with local proinflammatory cytokines and symptom severity. In vitro experiments demonstrated that neutrophilic polyp-derived MAIT cells promoted neutrophil migration, survival, and activation.

CONCLUSIONS

MAIT cells from neutrophilic CRSwNP demonstrate type 17 functional properties and promote neutrophil infiltration in nasal mucosa.

Sepsis induces non-classic innate immune memory in granulocytes

Secondary infection in patients with sepsis triggers a new wave of inflammatory response, which aggravates organ injury and increases mortality. Trained immunity boosts a potent and nonspecific response to the secondary challenge and has been considered beneficial for the host. Here, using a murine model of polymicrobial infection, we find that the primary infection reprograms granulocytes to boost enhanced inflammatory responses to the secondary infection, including the excessive production of inflammatory cytokines, respiratory burst, and augmented phagocytosis capacity. However, these reprogramed granulocytes exhibit "non-classic" characteristics of innate immune memory. Two mechanisms are independently involved in the innate immune memory of granulocytes: a metabolic shift in favor of glycolysis and fatty acid synthesis and chromatin remodeling leading to the transcriptional inactivity of genes encoding inhibitors of TLR4-initiated signaling pathways. Counteracting the deleterious effects of stressed granulocytes on anti-infection immunity might provide a strategy to fight secondary infections during sepsis.

The Role of Bacterial, Dentinal, Salivary, and Neutrophil Degradative Activity in Caries Pathogenesis

Until recently, it was widely accepted that bacteria participate in caries pathogenesis mainly through carbohydrate fermentation and acid production, which promote the dissolution of tooth components. Neutrophils, on the other hand, were considered white blood cells with no role in caries pathogenesis. Nevertheless, current literature suggests that both bacteria and neutrophils, among other factors, possess direct degradative activity towards both dentinal collagen type-1 and/or methacrylate resin-based restoratives and adhesives, the most common dental restoratives. Neutrophils are abundant leukocytes in the gingival sulcus, where they can readily reach adjacent tooth roots or gingival and cervical restorations and execute their degradative activity. In this review, we present the latest literature evidence for bacterial, dentinal, salivary, and neutrophil degradative action that may induce primary caries, secondary caries, and restoration failure.

Neutrophil subsets in noncancer liver diseases: Cellular crosstalk and therapeutic targets

Neutrophils are the most abundant circulating granulocytes, linking innate and adaptive immunity. Neutrophils can regulate inflammatory and immune responses through degranulation, reactive oxygen species generation, the production of cytokines and chemokines, and NETosis. Emerging evidence has indicated that neutrophils contribute to the pathogenesis of various noncancer liver diseases, including nonalcoholic fatty liver disease, alcohol-associated liver disease, hepatic ischemia-reperfusion injury, and liver fibrosis. Cellular interactions among neutrophils, other immune cells, and nonimmune cells constitute a complex network that regulates the immune microenvironment of the liver. This review summarizes novel neutrophil subtypes, including CD177+ neutrophils and low-density neutrophils. Moreover, we provide an overview of the cellular cros stalk of neutrophils in noncancer liver diseases, aiming to shed new light on mechanistic studies of novel neutrophil subtypes. In addition, we discuss the potential of neutrophils as therapeutic targets in noncancer liver diseases, including inhibitors targeting NETosis, granule proteins, and chemokines.

Fast and furious: The neutrophil and its armamentarium in health and disease

Neutrophils are powerful effector cells leading the first wave of acute host-protective responses. These innate leukocytes are endowed with oxidative and nonoxidative defence mechanisms, and play well-established roles in fighting invading pathogens. With microbicidal weaponry largely devoid of specificity and an all-too-well recognized toxicity potential, collateral damage may occur in neutrophil-rich diseases. However, emerging evidence suggests that neutrophils are more versatile, heterogeneous, and sophisticated cells than initially thought. At the crossroads of innate and adaptive immunity, neutrophils demonstrate their multifaceted functions in infectious and noninfectious pathologies including cancer, autoinflammation, and autoimmune diseases. Here, we discuss the kinetics of neutrophils and their products of activation from bench to bedside during health and disease, and provide an overview of the versatile functions of neutrophils as key modulators of immune responses and physiological processes. We focus specifically on those activities and concepts that have been validated with primary human cells.

The double-edged role of neutrophil heterogeneity in inflammatory diseases and cancers

Neutrophils are important immune cells act as the body's first line of defense against infection and respond to diverse inflammatory cues. Many studies have demonstrated that neutrophils display plasticity in inflammatory diseases and cancers. Clarifying the role of neutrophil heterogeneity in inflammatory diseases and cancers will contribute to the development of novel treatment strategies. In this review, we have presented a review on the development of the understanding on neutrophil heterogeneity from the traditional perspective and a high-resolution viewpoint. A growing body of evidence has confirmed the double-edged role of neutrophils in inflammatory diseases and tumors. This may be due to a lack of precise understanding of the role of specific neutrophil subsets in the disease. Thus, elucidating specific neutrophil subsets involved in diseases would benefit the development of precision medicine. Thusly, we have summarized the relevance and actions of neutrophil heterogeneity in inflammatory diseases and cancers comprehensively. Meanwhile, we also discussed the potential intervention strategy for neutrophils. This review is intended to deepen our understanding of neutrophil heterogeneity in inflammatory diseases and cancers, while hold promise for precise treatment of neutrophil-related diseases.

Mycobacterium tuberculosis in a Trap: The Role of Neutrophil Extracellular Traps in Tuberculosis

Mycobacterium tuberculosis complex causes tuberculosis (TB), a disease that causes pulmonary inflammation but can also affect other tissues. Despite macrophages having a defined role in TB immunopathogenesis, other innate immune cells, such as neutrophils, are involved in this process. These cells have high phagocytic ability and a microbial-killing machine comprised of enzymes, antimicrobial peptides, and reactive oxygen species. In the last two decades, a new neutrophil immune response, the neutrophil extracellular traps (NETs), has been intensely researched. NETs comprise DNA associated with histones, enzymes, and antimicrobial peptides. These structures are related to antimicrobial immune response and some immuno-pathogenesis mechanisms. This mini review highlights the role of NETs in tuberculosis and how they can be helpful as a diagnostic tool and/or therapeutic target.

Research progress on the neutrophil components and their interactions with immune cells in the development of psoriasis

BACKGROUND

Psoriasis is an immune-mediated chronic inflammatory disease, and currently it is widely believed that the IL-23/IL-17 axis and Th17 cells play a critical and central role. However, increasing evidence suggests that neutrophils may interact with a variety of immune cells to play an indispensable role in psoriasis.

MATERIALS AND METHODS

We searched the recent literature on psoriasis and neutrophils through databases such as PubMed and CNKI, and summarized the findings to draw conclusions.

RESULTS

Neutrophils can promote the development of psoriasis by secreting IL-23, IL-17, and cytokines with TH17 cell chemotaxis. Activated keratinocytes (KCs) can attract and activate neutrophils, induce the formation of neutrophil extracellular traps (NETs). KCs can also expose self-antigens which lead to strong autoimmune reactions. The granule proteins secreted by activated neutrophils can activate IL-36, which converts vulgaris psoriasis to generalized pustular psoriasis (GPP).

CONCLUSION

The function of neutrophils components and the interaction between neutrophils and immune cells play an essential role in the pathogenesis of psoriasis. The aim is to provide a theoretical basis for the exploration of targeted clinical treatments and fundamental research on the pathogenesis of psoriasis.

Tumor-neutrophil crosstalk promotes in vitro and in vivo glioblastoma progression

Introduction

The tumor microenvironment (TME) of glioblastoma (GB) is characterized by an increased infiltration of immunosuppressive cells that attenuate the antitumor immune response. The participation of neutrophils in tumor progression is still controversial and a dual role in the TME has been proposed. In this study, we show that neutrophils are reprogrammed by the tumor to ultimately promote GB progression.

Methods

Using in vitro and in vivo assays, we demonstrate the existence of bidirectional GB and neutrophil communication, directly promoting an immunosuppressive TME.

Results and discussion

Neutrophils have shown to play an important role in tumor malignancy especially in advanced 3D tumor model and Balb/c nude mice experiments, implying a time- and neutrophil concentration-dependent modulation. Studying the tumor energetic metabolism indicated a mitochondria mismatch shaping the TME secretome. The given data suggests a cytokine milieu in patients with GB that favors the recruitment of neutrophils, sustaining an anti-inflammatory profile which is associated with poor prognosis. Besides, glioma-neutrophil crosstalk has sustained a tumor prolonged activation via NETs formation, indicating the role of NFκB signaling in tumor progression. Moreover, clinical samples have indicated that neutrophil-lymphocyte ratio (NLR), IL-1β, and IL-10 are associated with poor outcomes in patients with GB.

Conclusion

These results are relevant for understanding how tumor progression occurs and how immune cells can help in this process.

c-Met Mediated Cytokine Network Promotes Brain Metastasis of Breast Cancer by Remodeling Neutrophil Activities

The brain is one of the most common metastatic sites among breast cancer patients, especially in those who have Her2-positive or triple-negative tumors. The brain microenvironment has been considered immune privileged, and the exact mechanisms of how immune cells in the brain microenvironment contribute to brain metastasis remain elusive. In this study, we found that neutrophils are recruited and influenced by c-Met high brain metastatic cells in the metastatic sites, and depletion of neutrophils significantly suppressed brain metastasis in animal models. Overexpression of c-Met in tumor cells enhances the secretion of a group of cytokines, including CXCL1/2, G-CSF, and GM-CSF, which play critical roles in neutrophil attraction, granulopoiesis, and homeostasis. Meanwhile, our transcriptomic analysis demonstrated that conditioned media from c-Met high cells significantly induced the secretion of lipocalin 2 (LCN2) from neutrophils, which in turn promotes the self-renewal of cancer stem cells. Our study unveiled the molecular and pathogenic mechanisms of how crosstalk between innate immune cells and tumor cells facilitates tumor progression in the brain, which provides novel therapeutic targets for treating brain metastasis.

Single-cell RNA-seq analysis reveals BHLHE40-driven pro-tumour neutrophils with hyperactivated glycolysis in pancreatic tumour microenvironment

OBJECTIVE

Innate immunity plays important roles in pancreatic ductal adenocarcinoma (PDAC), as non-T-cell-enriched tumour. Neutrophils are major players in innate immune system. Here, we aimed to explore the heterogeneity and pro-tumour mechanisms of neutrophils in PDAC.

DESIGN

We analysed single-cell transcriptomes of peripheral blood polymorphonuclear leucocytes (PMNs) and tumour-infiltrating immune cells from five patients with PDAC, and performed immunofluorescence/immunohistochemistry staining, multi-omics analysis and in vitro experiments to validate the discoveries of bioinformatics analysis.

RESULTS

Exploration of the heterogeneity of tumour-associated neutrophils (TANs) revealed a terminally differentiated pro-tumour subpopulation (TAN-1) associated with poor prognosis, an inflammatory subpopulation (TAN-2), a population of transitional stage that have just migrated to tumour microenvironment (TAN-3) and a subpopulation preferentially expressing interferon-stimulated genes (TAN-4). Glycolysis signature was upregulated along neutrophil transition trajectory, and TAN-1 was featured with hyperactivated glycolytic activity. The glycolytic switch of TANs was validated by integrative multi-omics approach of transcriptomics, proteomics and metabolomics analysis. Activation of glycolytic activity by LDHA overexpression induced immunosuppression and pro-tumour functions in neutrophil-like differentiated HL-60 (dHL-60) cells. Mechanistic studies revealed BHLHE40, downstream to hypoxia and endoplasmic reticulum stress, was a key regulator in polarisation of neutrophils towards TAN-1 phenotype, and direct transcriptional regulation of BHLHE40 on TAN-1 marker genes was demonstrated by chromatin immunoprecipitation assay. Pro-tumour and immunosuppression functions were observed in dHL-60 cells overexpressing BHLHE40. Importantly, immunohistochemistry analysis of PDAC tissues revealed the unfavourable prognostic value of BHLHE40+ neutrophils.

CONCLUSION

The dynamic properties of TANs revealed by this study will be helpful in advancing PDAC therapy targeting innate immunity.

Immunomodulatory effects of trans-anethole-treated Staphylococcus aureus Newman strain

In our former studies based on a human whole-blood model infected with trans-anethole (TA)-treated Staphylococcus aureus Newman strain, we have observed that selected parameters/mechanisms of innate and acquired immune response were more enhanced in comparison to samples infected with non-treated bacteria. Due to this observation, the current study aimed to evaluate the concentration of selected proteins involved in both types of responses (IL-1α, IL-1β, IL-2, IL-6, IL-12, IL-17, TNF-α, IFN-γ, G-CSF, C5a, CCL1-CCL5, CXCL1, CXCL2, CXCL9-CXCL11, MMP-8, TLR2, and PGLYRP1) in healthy participants' plasma after blood stimulation of TA-treated S. aureus Newman strain. Determination of analyzed protein concentration was conducted using Luminex and ELISA assays. Based on the results, it has been proven that the immunomodulatory potential of TA-treated S. aureus Newman strain on increasing IL-1β, IL-6, TNF-α, IL-12, G-CSF, C5a, CCL2-CCL4, CXCL1, CXCL2, MMP-8 and PGLYRP1 levels in plasma. Moreover, it has been also demonstrated an association between TNF-α and CCL4 in a blood model infected with TA-treated cells. More research is warranted to find more underlying mechanisms involved in the effects of TA-treated S. aureus Newman in human blood, mainly whether the observed "immunity boost" can be regulated after bacteria elimination. Therefore, the potential of TA should be further explored to understand under which conditions it might help treat or prevent infections caused by S. aureus.

Gram-negative bacterial infection causes aggravated innate immune response in sepsis: Studies from clinical samples and cellular models

Bacterial infection is the most common cause for sepsis. The purpose of this study was to evaluate the impact of different bacterial infection on sepsis based on human samples and cellular experiments. Physiological indexes and prognostic information of 121 sepsis patients were analysed based on whether they had a gram-positive or gram-negative bacterial infection. Moreover, murine RAW264.7 macrophages were treated with lipopolysaccharide (LPS) or peptidoglycan (PG) to simulate infection with gram-negative or gram-positive bacteria in sepsis, respectively. Exosomes derived from the macrophages were extracted for transcriptome sequencing. In patients with sepsis, most gram-positive bacterial infections were Staphylococcus aureus, and gram-negative infections were Escherichia coli. Gram-negative bacterial infection was significantly associated with high neutrophil and interleukin (IL)-6 levels in blood and shorter prothrombin (PT) and activated partial thromboplastin time (APTT). Intriguingly, the survival prognosis of sepsis patients was not affected by the type of bacterial infection, but it was significantly related to fibrinogen. Protein transcriptome sequencing of the macrophage-derived exosomes showed that differentially expressed proteins were significantly enriched in megakaryocyte differentiation, leukocyte and lymphocyte-mediated immunity, and complement and coagulation cascade pathways. The complement and coagulation-related proteins were significantly upregulated after LPS induction, which explained the shortened PT and APTT in gram-negative bacterial sepsis. Bacterial infection did not affect mortality in sepsis but did alter the host response. The immune disorder induced by gram-negative infection was more severe than that produced by gram-positive infection. This study provides references for the rapid identification and molecular research of different bacterial infections in sepsis.

METTL3-mediated m6A mRNA methylation regulates neutrophil activation through targeting TLR4 signaling

N6-methyladenosine (m6A) modification accounts for the most prevalent mRNA internal modification and has emerged as a widespread regulatory mechanism in multiple physiological processes. We address a role of methyltransferase-like protein 3 (METTL3) in neutrophil activation. METTL3 controls neutrophil release from bone marrow to circulation through surface expression of CXC chemokine receptor 2 (CXCR2) in a Toll-like receptor 4 (TLR4) signaling-dependent manner in lipopolysaccharide (LPS)-induced endotoxemia. We show that the mRNA of TLR4 is modified by m6A, exhibiting increased translation and slowed degradation simultaneously, leading to elevated protein levels of TLR4, which eventually promotes the TLR4 signaling activation of neutrophil. The reduced expression of TLR4 lowers cytokine secretion in METTL3-deleted neutrophils upon LPS stimulation through TLR4/Myd88/nuclear factor κB (NF-κB) signaling. Collectively, these data demonstrate that METTL3 modulation of TLR4 expression is a critical determinant of neutrophil activation in endotoxemia.

The Regulation of Neutrophil Migration in Patients with Sepsis: The Complexity of the Molecular Mechanisms and Their Modulation in Sepsis and the Heterogeneity of Sepsis Patients

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Common causes include gram-negative and gram-positive bacteria as well as fungi. Neutrophils are among the first cells to arrive at an infection site where they function as important effector cells of the innate immune system and as regulators of the host immune response. The regulation of neutrophil migration is therefore important both for the infection-directed host response and for the development of organ dysfunctions in sepsis. Downregulation of CXCR4/CXCL12 stimulates neutrophil migration from the bone marrow. This is followed by transmigration/extravasation across the endothelial cell barrier at the infection site; this process is directed by adhesion molecules and various chemotactic gradients created by chemotactic cytokines, lipid mediators, bacterial peptides, and peptides from damaged cells. These mechanisms of neutrophil migration are modulated by sepsis, leading to reduced neutrophil migration and even reversed migration that contributes to distant organ failure. The sepsis-induced modulation seems to differ between neutrophil subsets. Furthermore, sepsis patients should be regarded as heterogeneous because neutrophil migration will possibly be further modulated by the infecting microorganisms, antimicrobial treatment, patient age/frailty/sex, other diseases (e.g., hematological malignancies and stem cell transplantation), and the metabolic status. The present review describes molecular mechanisms involved in the regulation of neutrophil migration; how these mechanisms are altered during sepsis; and how bacteria/fungi, antimicrobial treatment, and aging/frailty/comorbidity influence the regulation of neutrophil migration.

Neutrophils in host defense, healing, and hypersensitivity: Dynamic cells within a dynamic host

Neutrophils are cells of the innate immune system that are extremely abundant in vivo and respond quickly to infection, injury, and inflammation. Their constant circulation throughout the body makes them some of the first responders to infection, and indeed they play a critical role in host defense against bacterial and fungal pathogens. It is now appreciated that neutrophils also play an important role in tissue healing after injury. Their short life cycle, rapid response kinetics, and vast numbers make neutrophils a highly dynamic and potentially extremely influential cell population. It has become clear that they are highly integrated with other cells of the immune system and can thus exert critical effects on the course of an inflammatory response; they can further impact tissue homeostasis and recovery after challenge. In this review, we discuss the fundamentals of neutrophils in host defense and healing; we explore the relationship between neutrophils and the dynamic host environment, including circadian cycles and the microbiome; we survey the field of neutrophils in asthma and allergy; and we consider the question of neutrophil heterogeneity-namely, whether there could be specific subsets of neutrophils that perform different functions in vivo.

Neutrophils in the periodontium: Interactions with pathogens and roles in tissue homeostasis and inflammation

Neutrophils are of key importance in periodontal health and disease. In their absence or when they are functionally defective, as occurs in certain congenital disorders, affected individuals develop severe forms of periodontitis in early age. These observations imply that the presence of immune-competent neutrophils is essential to homeostasis. However, the presence of supernumerary or hyper-responsive neutrophils, either because of systemic priming or innate immune training, leads to imbalanced host-microbe interactions in the periodontium that culminate in dysbiosis and inflammatory tissue breakdown. These disease-provoking imbalanced interactions are further exacerbated by periodontal pathogens capable of subverting neutrophil responses to their microbial community's benefit and the host's detriment. This review attempts a synthesis of these findings for an integrated view of the neutrophils' ambivalent role in periodontal disease and, moreover, discusses how some of these concepts underpin the development of novel therapeutic approaches to treat periodontal disease.

Neutrophil-to-lymphocyte ratio is a risk indicator of Guillain-Barré syndrome and is associated with severity and short-term prognosis

Introduction

Guillain-Barré syndrome (GBS) is an autoimmune disorder targeting the peripheral nervous system. The neutrophil-to-lymphocyte ratio (NLR), a simple indicator of immune function, is potentially related to its incidence and severity; however, this should be confirmed. We aimed to evaluate the role of NLR in the diagnosis, severity, and prognosis of GBS.

Methods

Data of GBS patients and controls visiting our hospital from January 2010 to December 2020 were retrospectively analyzed (Clinical trial registration: ChiCTR2100053540). Risk factors were determined through logistic regression. Smoothing curves, receiver-operating characteristic curves, and forest plots were drawn.

Results

We included 136 GBS patients and 211 controls. NLR, as a continuous variable, was associated with GBS risk (OR, 2.32; 95% CI, 1.68-3.21; p < 0.001), severe functional disability (OR, 1.23; 95% CI, 1.06-1.43; p = 0.006), severe weakness (OR, 1.19; 95% CI, 1.06-1.35, p = 0.004), and short-term prognosis (OR, 1.21; 95% CI, 1.08-1.36; p = 0.001). NLR was more strongly associated with GBS risk in older (≥60 years) (OR, 7.17; 95% CI, 2.38-21.61) or male (OR, 2.88; 95% CI, 1.78-4.64) patients than in younger (<60 years) (OR, 1.88; 95% CI, 1.37-2.57) or female (OR, 1.85; 95% CI, 1.24-2.77) patients. NLR was significantly associated with severe functional disability in faster disease progression (OR, 1.53; 95% CI, 1.03-12.29) and male patients (OR, 1.41; 95% CI, 1.03-1.92) versus in slower disease progression (OR, 1.12; 95% CI, 0.77-1.64) and female patients (OR, 1.12; 95% CI, 0.77-1.64).

Conclusions

NLR may be an independent GBS risk factor and predictor of severe functional disability, severe weakness, and short-term prognosis.

Human neutrophils ≠ murine neutrophils: Does it matter?

Human and murine neutrophils differ with respect to representation in blood, receptors, nuclear morphology, signaling pathways, granule proteins, NADPH oxidase regulation, magnitude of oxidant and hypochlorous acid production, and their repertoire of secreted molecules. These differences often matter and can undermine extrapolations from murine studies to clinical care, as illustrated by several failed therapeutic interventions based on mouse models. Likewise, coevolution of host and pathogen undercuts fidelity of murine models of neutrophil-predominant human infections. However, murine systems that accurately model the human condition can yield insights into human biology difficult to obtain otherwise. The challenge for investigators who employ murine systems is to distinguish models from pretenders and to know when the mouse provides biologically accurate insights. Testing with human neutrophils observations made in murine systems would provide a safeguard but is not always possible. At a minimum, studies that use exclusively murine neutrophils should have accurate titles supported by data and restrict conclusions to murine neutrophils and not encompass all neutrophils. For now, the integration of evidence from studies of neutrophil biology performed using valid murine models coupled with testing in vitro of human neutrophils combines the best of both approaches to elucidate the mysteries of human neutrophil biology.

GPR109A controls neutrophil extracellular traps formation and improve early sepsis by regulating ROS/PAD4/Cit-H3 signal axis

BACKGROUND

Neutrophil extracellular traps (NETs) is the key means for neutrophils to resist bacterial invasion. Sepsis is a systemic inflammatory response syndrome caused by infection.

METHODS

In our study, qRT-PCR was used to detect the gene expression in neutrophils, Western blot was used to detect the protein expression in mouse tissues and neutrophils, flow cytometry was used to detect the purity of neutrophils in the whole blood and immunofluorescence was used to detect the NETs formation.

RESULTS

In this study, we analyzed the NETs formation in the blood of patients with sepsis. The results showed that a large number of NETs appeared. And the expression of GPR109A in neutrophils of patients with sepsis was significantly up regulated. Then we collected neutrophils from WT mice and GPR109A^-/- mice and found that GPR109A knockout could significantly inhibit the early NETs formation of neutrophils. The results also showed that knockout of GPR109A or inhibition of the NETs formation could increase the inflammatory response of liver, spleen, lung and kidney in mice, thus affecting the disease process of sepsis. Then we observed the death of mice in 16 days. The results showed that inhibiting the NETs formation could significantly affect the early mortality of mice, while knocking out GPR109A could directly affect the mortality of the whole period.

CONCLUSIONS

This study confirmed the regulatory effect of GPR109A on early NETs formation for the first time, and provided a new target for the treatment of sepsis.

Distinct phenotype of neutrophil, monocyte, and eosinophil populations indicates altered myelopoiesis in a subset of patients with multiple myeloma

Hematologic malignancies, including multiple myeloma (MM), promote systemic immune dysregulation resulting in an alteration and increased plasticity of myeloid cell subsets. To determine the heterogeneity of the myeloid cell compartment in the peripheral blood of patients with MM, we performed a detailed investigation of the phenotype and function of myeloid subpopulations. We report that a subset of MM patients exhibits a specific myeloid cell phenotype indicative of altered myelopoiesis characterized by significant changes in the properties of circulating granulocytic, monocytic, and eosinophilic populations. The subset, referred to as MM2, is defined by a markedly elevated level of CD64 (FcγRI) on the surface of circulating neutrophils. Compared to healthy controls or MM1 patients displaying intermediate levels of CD64, neutrophils from MM2 patients exhibit a less differentiated phenotype, low levels of CD10 and CXC chemokine receptor 2 (CXCR2), increased capacity for the production of mitochondrial reactive oxygen species, and an expansion of CD16^neg immature neutrophil subset. Classical and patrolling monocytes from MM2 patients express elevated levels of CD64 and activation markers. MM2 eosinophils display lower levels of C-C Chemokine receptor 3 (CCR3), Toll-like receptor 4 (TLR4, CD284), and tissue factor (TF, CD142). The MM2 (CD64^high) phenotype is independent of age, race, sex, and treatment type. Characteristic features of the MM2 (CD64^high) phenotype are associated with myeloma-defining events including elevated involved/uninvolved immunoglobulin free light chain (FLC) ratio at diagnosis. Detailed characterization of the altered myeloid phenotype in multiple myeloma will likely facilitate the identification of patients with an increased risk of disease progression and open new avenues for the rational design of novel therapeutic approaches.

Worsening Thrombotic Complication of Atherosclerotic Plaques Due to Neutrophils Extracellular Traps: A Systematic Review

Neutrophil extracellular traps (NETs) recently emerged as a newly recognized contributor to venous and arterial thrombosis. These strands of DNA, extruded by activated or dying neutrophils, decorated with various protein mediators, become solid-state reactors that can localize at the critical interface of blood with the intimal surface of diseased arteries alongside propagating and amplifying the regional injury. NETs thus furnish a previously unsuspected link between inflammation, innate immunity, thrombosis, oxidative stress, and cardiovascular diseases. In response to disease-relevant stimuli, neutrophils undergo a specialized series of reactions that culminate in NET formation. DNA derived from either nuclei or mitochondria can contribute to NET formation. The DNA liberated from neutrophils forms a reticular mesh that resembles morphologically a net, rendering the acronym NETs particularly appropriate. The DNA backbone of NETs not only presents intrinsic neutrophil proteins (e.g., MPO (myeloperoxidase) and various proteinases) but can congregate other proteins found in blood (e.g., tissue factor procoagulant). This systematic review discusses the current hypothesis of neutrophil biology, focusing on the triggers and mechanisms of NET formation. Furthermore, the contribution of NETs to atherosclerosis and thrombosis is extensively addressed. Again, the use of NET markers in clinical trials was considered. Ultimately, given the vast body of the published literature, we aim to integrate the experimental evidence with the growing body of clinical information relating to NET critically.

Development of Nomogram Models Based on Peripheral Blood Score and Clinicopathological Parameters to Predict Preoperative Advanced Stage and Prognosis for Epithelial Ovarian Cancer Patients

Purpose

Nutritional and inflammatory states are crucial in cancer development. The purpose of this study is to construct a scoring system grounded on peripheral blood parameters associated with nutrition and inflammation and explore its value in stage, overall survival (OS), and progression-free survival (PFS) prediction for epithelial ovarian cancer (EOC) patients.

Patients and Methods

Four hundred and fifty-three EOC patients were retrospectively identified and their clinical data and relevant peripheral blood parameters were collected. The ratio of neutrophil to lymphocyte, lymphocyte to monocyte, fibrinogen to lymphocyte, total cholesterol to lymphocyte and albumin level were calculated and dichotomized. A scoring system named peripheral blood score (PBS) was constructed. Univariate and multivariate Logistic or Cox regression analyses were used to select independent factors; these factors were then used to develop nomogram models of advanced stage and OS, PFS, respectively. The internal validation and DCA analysis were performed to evaluate models.

Results

Lower PBS indicated a better prognosis and higher PBS indicated inferior. High PBS is associated with advanced stage, high CA125, serous histological type, poor differentiation, and accompanied ascites. The logistic regression showed age, CA125, and PBS were independent factors for the FIGO III-IV stage. The nomogram models for advanced FIGO stage based on these factors showed good efficiency. FIGO stage, residual disease, and PBS were independent factors affecting OS and PFS, the nomogram models composed of these factors had good performance. DCA curves revealed the models augmented net benefits.

Conclusion

PBS can be a noninvasive biomarker for EOC patients' prognosis. The related nomogram models could be powerful, cost-effective tools to provide information of advanced stage, OS, and PFS for EOC patients.

Role of the human vaginal microbiota in the regulation of inflammation and sexually transmitted infection acquisition: Contribution of the non-human primate model to a better understanding?

The human vaginal microbiota has a central role in the regulation of the female reproductive tract (FRT) inflammation. Indeed, on one hand an optimal environment leading to a protection against sexually transmitted infections (STI) is associated with a high proportion of Lactobacillus spp. (eubiosis). On the other hand, a more diverse microbiota with a high amount of non-Lactobacillus spp. (dysbiosis) is linked to a higher local inflammation and an increased STI susceptibility. The composition of the vaginal microbiota is influenced by numerous factors that may lead to a dysbiotic environment. In this review, we first discuss how the vaginal microbiota composition affects the local inflammation with a focus on the cytokine profiles, the immune cell recruitment/phenotype and a large part devoted on the interactions between the vaginal microbiota and the neutrophils. Secondly, we analyze the interplay between STI and the vaginal microbiota and describe several mechanisms of action of the vaginal microbiota. Finally, the input of the NHP model in research focusing on the FRT health including vaginal microbiota or STI acquisition/control and treatment is discussed.

SARS-CoV-2-Associated ssRNAs Activate Human Neutrophils in a TLR8-Dependent Fashion

COVID-19 disease is characterized by a dysregulation of the innate arm of the immune system. However, the mechanisms whereby innate immune cells, including neutrophils, become activated in patients are not completely understood. Recently, we showed that GU-rich RNA sequences from the SARS-CoV-2 genome (i.e., SCV2-RNA1 and SCV2-RNA2) activate dendritic cells. To clarify whether human neutrophils may also represent targets of SCV2-RNAs, neutrophils were treated with either SCV2-RNAs or, as a control, R848 (a TLR7/8 ligand), and were then analyzed for several functional assays and also subjected to RNA-seq experiments. Results highlight a remarkable response of neutrophils to SCV2-RNAs in terms of TNFα, IL-1ra, CXCL8 production, apoptosis delay, modulation of CD11b and CD62L expression, and release of neutrophil extracellular traps. By RNA-seq experiments, we observed that SCV2-RNA2 promotes a transcriptional reprogramming of neutrophils, characterized by the induction of thousands of proinflammatory genes, similar to that promoted by R848. Furthermore, by using CU-CPT9a, a TLR8-specific inhibitor, we found that SCV2-RNA2 stimulates neutrophils exclusively via TLR8-dependent pathways. In sum, our study proves that single-strand RNAs from the SARS-CoV-2 genome potently activate human neutrophils via TLR8, thus uncovering a potential mechanism whereby neutrophils may contribute to the pathogenesis of severe COVID-19 disease.

Myeloperoxidase: Regulation of Neutrophil Function and Target for Therapy

Neutrophils, the most abundant white blood cells in humans, are critical for host defense against invading pathogens. Equipped with an array of antimicrobial molecules, neutrophils can eradicate bacteria and clear debris. Among the microbicide proteins is the heme protein myeloperoxidase (MPO), stored in the azurophilic granules, and catalyzes the formation of the chlorinating oxidant HOCl and other oxidants (HOSCN and HOBr). MPO is generally associated with killing trapped bacteria and inflicting collateral tissue damage to the host. However, the characterization of non-enzymatic functions of MPO suggests additional roles for this protein. Indeed, evolving evidence indicates that MPO can directly modulate the function and fate of neutrophils, thereby shaping immunity. These actions include MPO orchestration of neutrophil trafficking, activation, phagocytosis, lifespan, formation of extracellular traps, and MPO-triggered autoimmunity. This review scrutinizes the multifaceted roles of MPO in immunity, focusing on neutrophil-mediated host defense, tissue damage, repair, and autoimmunity. We also discuss novel therapeutic approaches to target MPO activity, expression, or MPO signaling for the treatment of inflammatory and autoimmune diseases.

Impact of Siponimod on Enteric and Central Nervous System Pathology in Late-Stage Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). Although immune modulation and suppression are effective during relapsing-remitting MS, secondary progressive MS (SPMS) requires neuroregenerative therapeutic options that act on the CNS. The sphingosine-1-phosphate receptor modulator siponimod is the only approved drug for SPMS. In the pivotal trial, siponimod reduced disease progression and brain atrophy compared with placebo. The enteric nervous system (ENS) was recently identified as an additional autoimmune target in MS. We investigated the effects of siponimod on the ENS and CNS in the experimental autoimmune encephalomyelitis model of MS. Mice with late-stage disease were treated with siponimod, fingolimod, or sham. The clinical disease was monitored daily, and treatment success was verified using mass spectrometry and flow cytometry, which revealed peripheral lymphopenia in siponimod- and fingolimod-treated mice. We evaluated the mRNA expression, ultrastructure, and histopathology of the ENS and CNS. Single-cell RNA sequencing revealed an upregulation of proinflammatory genes in spinal cord astrocytes and ependymal cells in siponimod-treated mice. However, differences in CNS and ENS histopathology and ultrastructural pathology between the treatment groups were absent. Thus, our data suggest that siponimod and fingolimod act on the peripheral immune system and do not have pronounced direct neuroprotective effects.

Emerging roles of neutrophils in immune homeostasis

Neutrophils, the most abundant innate immune cells, play essential roles in the innate immune system. As key innate immune cells, neutrophils detect intrusion of pathogens and initiate immune cascades with their functions; swarming (arresting), cytokine production, degranulation, phagocytosis, and projection of neutrophil extracellular trap. Because of their short lifespan and consumption during immune response, neutrophils need to be generated consistently, and generation of newborn neutrophils (granulopoiesis) should fulfill the environmental/systemic demands for training in cases of infection. Accumulating evidence suggests that neutrophils also play important roles in the regulation of adaptive immunity. Neutrophil-mediated immune responses end with apoptosis of the cells, and proper phagocytosis of the apoptotic body (efferocytosis) is crucial for initial and post resolution by producing tolerogenic innate/adaptive immune cells. However, inflammatory cues can impair these cascades, resulting in systemic immune activation; necrotic/pyroptotic neutrophil bodies can aggravate the excessive inflammation, increasing inflammatory macrophage and dendritic cell activation and subsequent T_H1/T_H17 responses contributing to the regulation of the pathogenesis of autoimmune disease. In this review, we briefly introduce recent studies of neutrophil function as players of immune response.