Regulation of Neutrophil Degranulation and Cytokine Secretion: A Novel Model Approach Based on Linear Fitting

Induction, amplification, and propagation of diabetic retinopathy-associated inflammatory cytokines between human retinal microvascular endothelial and Müller cells and in the mouse retina

Ocular levels of IL-1β, TNFα, IL-8, and IL-6 correlate with progression of diabetic retinopathy (DR). Müller cells (MC), which are crucial to maintaining retinal homeostasis, are targets and sources of these cytokines. We explored the relative capacities of these four DR-associated cytokines to amplify inflammatory signal expression both in and between human MC (hMC) and retinal microvascular endothelial cells (hRMEC) and in the mouse retina. Of the four cytokines, IL-1β was the most potent stimulus of transcriptomic alterations in hMC and hRMEC in vitro, as well as in the mouse retina after intravitreal injection in vivo. Stimulation with IL-1β significantly induced expression of all four transcripts in hMC and hRMEC. TNFα significantly induced expression of some, but not all, of the four transcripts in each cell, while neither IL-8 nor IL-6 showed significant induction in either cell. Similarly, conditioned media (CM) derived from hMC or hRMEC treated with IL-1β, but not TNFα, upregulated inflammatory cytokine transcripts in the reciprocal cell type. hRMEC responses to hMC-derived CM were dependent on IL-1R activation. In addition, we observed a correlation between cytokine expression changes following direct and CM stimulation and NFκB-p65 nuclear translocation in both hMC and hRMEC. Finally, in mice, intravitreal injections of IL-1β, but not TNFα, induced retinal expression of Il1b and CXCL8 homologues Cxcl1, Cxcl2, Cxcl3, and Cxcl5, encoding pro-angiogenic chemokines. Our results suggest that expression of IL-1β, TNFα, IL-8, and IL-6 may be initiated, propagated, and sustained by autocrine and paracrine signals in hRMEC and hMC through a process involving IL-1β and NFκB. Targeting these signals may help thwart inflammatory amplification, preventing progression to vision-threatening stages and preserving sight.

Purified granulocytes in extracorporeal cell therapy: A multifaceted approach to combat sepsis-induced immunoparalysis

BACKGROUND

Immune cell dysfunction plays a central role in sepsis-induced immunoparalysis. Targeted treatment using healthy donor immune cell transfusions, particularly granulocyte concentrates (GC) potentially induces tissue damage. Initial trials using GC in an extracorporeal immune cell perfusion system provided evidence for beneficial effects with fewer side effects, by separating patient and donor immune cell compartments. A multicenter clinical trial is exploring feasibility and effects of a 6-h treatment (NCT06143137). This ex vivo study examines technical feasibility and cellular effects of an extended treatment interval up to 24 h.

METHODS

Standard GC were purified to increase the potential storage time and subsequently implemented in the extracorporeal immune cell perfusion system. Parameters assessed included cell viability, phagocytosis activity, oxidative burst, cytokine release, and metabolic parameters of purified. GC during an extended circulation time of up to 24 h.

RESULTS

After storage of 72 h granulocytes were viable throughout the study period and exhibited preserved functionality and metabolic activity. The findings highlight a time-dependent nature of cytokine release by neutrophils in the extracorporeal circuit, as cytokine secretion patterns showed IL-8 peaking within 6 h, while MCP-1, IL-6, IL-1β, and TNF-α increased after 24 h of circulation.

CONCLUSION

Purified GC remain functional after 72 h of storage and additional 24 h in the circulating treatment model. Cytokine secretion patterns revealed a significant increase, especially between 10 and 24 h of treatment. Extending treatment time holds promise for enhancing immune response against sepsis-induced immunoparalysis. These findings provide valuable insights for optimizing immune-targeted therapeutic interventions.

Effects of amber LED on inflammatory and regulatory monocytes and lymphocytes

The primary objective of the present study was to assess the impact of amber LED photobiomodulation (PBM) on human monocytes and lymphocytes that were polarized into proinflammatory and regulatory/reparative phenotypes. Human leukocytes were polarized with LPS or LPS + IL-4 for 2 h and irradiated after 2 and 6 h with amber LED (590 nm). Cell absorbance spectrum and gene and protein expression of IL-1β, IL-6, IL-10, IL-17, TNF-α and IFNγ determined after 24 h. The results showed that irradiation did not significantly alter absorbance of non-polarized monocytes, whereas irradiated polarized monocytes presented reduction in absorbance in 625-850 nm region. Irradiated monocytes polarized with LPS + IL-4 presented reduction in absorbance in 600-725 nm region compared to non-irradiated group. Irradiated non-polarized lymphocytes presented absorbance peaks between 650 and 820 nm not seen in non-irradiated group. No difference was found in absorbance pattern of polarized lymphocytes after irradiation. Irradiation led to reduction in protein synthesis of IL-6 and TNFα in monocytes polarized to proinflammatory phenotype and increase in production of IL-17 in lymphocytes. Irradiation reduced production of IL-10 in monocytes and lymphocytes polarized to immunoregulatory phenotype. In conclusion, amber LED modulates light absorbance and expression of important cytokines in inflammatory/repair processes in monocytes and lymphocytes.

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.

Inflammation in Myocardial Ischemia/Reperfusion Injury: Underlying Mechanisms and Therapeutic Potential

Acute myocardial infarction (MI) occurs when blood flow to the myocardium is restricted, leading to cardiac damage and massive loss of viable cardiomyocytes. Timely restoration of coronary flow is considered the gold standard treatment for MI patients and limits infarct size; however, this intervention, known as reperfusion, initiates a complex pathological process that somewhat paradoxically also contributes to cardiac injury. Despite being a sterile environment, ischemia/reperfusion (I/R) injury triggers inflammation, which contributes to infarct expansion and subsequent cardiac remodeling and wound healing. The immune response is comprised of subsets of both myeloid and lymphoid-derived cells that act in concert to modulate the pathogenesis and resolution of I/R injury. Multiple mechanisms, including altered metabolic status, regulate immune cell activation and function in the setting of acute MI, yet our understanding remains incomplete. While numerous studies demonstrated cardiac benefit following strategies that target inflammation in preclinical models, therapeutic attempts to mitigate I/R injury in patients were less successful. Therefore, further investigation leveraging emerging technologies is needed to better characterize this intricate inflammatory response and elucidate its influence on cardiac injury and the progression to heart failure.

Severe chronic non-bacterial osteomyelitis in combination with total MPO deficiency and responsiveness to TNFα inhibition

We describe a female patient suffering from severe chronic non-bacterial osteomyelitis (CNO) with systemic inflammation and advanced malnutrition and complete deficiency of myeloperoxidase (MPO). CNO is a rare autoinflammatory bone disorder associated with dysregulation of the innate immune system. MPO deficiency is a genetic disorder with partial or complete absence of the phagocyte peroxidase MPO. MPO deficiency has no established clinical phenotype but reports indicate increased susceptibility to infection and chronic inflammation. The patient's symptoms began at 10 years of age with pain in the thighs, systemic inflammation and malnutrition. She was diagnosed with CNO at 14 years of age. Treatment with nonsteroidal anti-inflammatory drugs, corticosteroids, bisphosphonates or IL1-receptor antagonists (anakinra) did not relieve the symptoms. However, the patient responded instantly and recovered from her clinical symptoms when treated with TNFα blockade (adalimumab). Three years after treatment initiation adalimumab was withdrawn, resulting in rapid symptom recurrence. When reintroducing adalimumab, the patient promptly responded and went into remission. In addition to clinical and laboratory profiles, neutrophil functions (reactive oxygen species, ROS; neutrophil extracellular traps, NETs; degranulation; apoptosis; elastase activity) were investigated both in a highly inflammatory state (without treatment) and in remission (on treatment). At diagnosis, neither IL1β, IL6, nor TNFα was significantly elevated in serum, but since TNFα blockade terminated the inflammatory symptoms, the disease was likely TNFα-driven. All neutrophil parameters were normal both during treatment and treatment withdrawal, except for MPO-dependent intracellular ROS- and NET formation. The role of total MPO deficiency for disease etiology and severity is discussed.

Enterococcus faecalis suppresses Staphylococcus aureus-induced NETosis and promotes bacterial survival in polymicrobial infections

Enterococcus faecalis is an opportunistic pathogen that is frequently co-isolated with other microbes in wound infections. While E. faecalis can subvert the host immune response and promote the survival of other microbes via interbacterial synergy, little is known about the impact of E. faecalis-mediated immune suppression on co-infecting microbes. We hypothesized that E. faecalis can attenuate neutrophil-mediated responses in mixed-species infection to promote survival of the co-infecting species. We found that neutrophils control E. faecalis infection via phagocytosis, ROS production, and degranulation of azurophilic granules, but it does not trigger neutrophil extracellular trap formation (NETosis). However, E. faecalis attenuates Staphylococcus aureus-induced NETosis in polymicrobial infection by interfering with citrullination of histone, suggesting E. faecalis can actively suppress NETosis in neutrophils. Residual S. aureus-induced NETs that remain during co-infection do not impact E. faecalis, further suggesting that E. faecalis possess mechanisms to evade or survive NET-associated killing mechanisms. E. faecalis-driven reduction of NETosis corresponds with higher S. aureus survival, indicating that this immunomodulating effect could be a risk factor in promoting the virulence polymicrobial infection. These findings highlight the complexity of the immune response to polymicrobial infections and suggest that attenuated pathogen-specific immune responses contribute to pathogenesis in the mammalian host.

Evaluation of the innate immune response of caprine neutrophils against Mycobacterium avium subspecies paratuberculosis in vitro

Neutrophils constitute an essential component of the innate immune response, readily killing most bacteria through phagocytosis, degranulation, and the release of neutrophil extracellular traps (NETs) among other mechanisms. These cells play an unclear role in mycobacterial infections such as Mycobacterium avium subspecies paratuberculosis (Map), the etiological agent of paratuberculosis, and its response is particularly understudied in ruminants. Herein, a wide set of techniques were adapted, or newly developed, to study the in vitro response of caprine neutrophils after Map infection. Immunofluorescence was used to demonstrate, simultaneously, chemotaxis, phagocytosis, degranulation, and NETs. The quantification of neutrophil phagocytic activity against Map at a 1:10 multiplicity of infection (MOI), through flow cytometry, showed values that varied from 4.54 to 5.63% of phagocyting neutrophils. By immunofluorescence, a 73.3 ± 14.5% of the fields showed NETs, and the mean release of DNA, attributable to NETosis, calculated through a fluorometric method, was 16.2 ± 3.5%. In addition, the RNA expression of TGF-β, TNF and IL-1β cytokines, measured through reverse transcription qPCR, was significantly higher in the two latter. Overall, neutrophil response was proportional to the number of bacteria. This work confirms that the simultaneous study of several neutrophil mechanisms, and the combination of different methodologies, are essential to reach a comprehensive understanding of neutrophil response against pathogens, demonstrates that, in vitro, caprine neutrophils display a strong innate response against Map, using their entire repertoire of effector functions, and sets the basis for further in vitro and in vivo studies on the role of neutrophils in paratuberculosis.

Neutrophil (dys)function due to altered immuno-metabolic axis in type 2 diabetes: implications in combating infections

Metabolic and inflammatory pathways are highly interdependent, and both systems are dysregulated in Type 2 diabetes (T2D). T2D is associated with pre-activated inflammatory signaling networks, aberrant cytokine production and increased acute phase reactants which leads to a pro-inflammatory 'feed forward loop'. Nutrient 'excess' conditions in T2D with hyperglycemia, elevated lipids and branched-chain amino acids significantly alter the functions of immune cells including neutrophils. Neutrophils are metabolically active cells and utilizes energy from glycolysis, stored glycogen and β-oxidation while depending on the pentose phosphate pathway for NADPH for performing effector functions such as chemotaxis, phagocytosis and forming extracellular traps. Metabolic changes in T2D result in constitutive activation and impeded acquisition of effector or regulatory activities of neutrophils and render T2D subjects for recurrent infections. Increased flux through the polyol and hexosamine pathways, elevated production of advanced glycation end products (AGEs), and activation of protein kinase C isoforms lead to (a) an enhancement in superoxide generation; (b) the stimulation of inflammatory pathways and subsequently to (c) abnormal host responses. Neutrophil dysfunction diminishes the effectiveness of wound healing, successful tissue regeneration and immune surveillance against offending pathogens. Hence, Metabolic reprogramming in neutrophils determines frequency, severity and duration of infections in T2D. The present review discusses the influence of the altered immuno-metabolic axis on neutrophil dysfunction along with challenges and therapeutic opportunities for clinical management of T2D-associated infections.

A tissue chip with integrated digital immunosensors: In situ brain endothelial barrier cytokine secretion monitoring

Organ-on-a-chip platforms have potential to offer more cost-effective, ethical, and human-resembling models than animal models for disease study and drug discovery. Particularly, the Blood-Brain-Barrier-on-a-chip (BBB-oC) has emerged as a promising tool to investigate several neurological disorders since it promises to provide a model of the multifunctional tissue working as an important node to control pathogen entry, drug delivery and neuroinflammation. A comprehensive understanding of the multiple physiological functions of the tissue model requires biosensors detecting several tissue-secreted substances in a BBB-oC system. However, current sensor-integrated BBB-oC platforms are only available for tissue membrane integrity characterization based on permeability measurement. Protein secretory pathways are closely associated with the tissue's various diseased conditions. At present, no biosensor-integrated BBB-oC platform exists that permits in situ tissue protein secretion analysis over time, which prohibits researchers from fully understanding the time-evolving pathology of a tissue barrier. Herein, the authors present a platform named "Digital Tissue-BArrier-CytoKine-counting-on-a-chip (DigiTACK)," which integrates digital immunosensors into a tissue chip system and demonstrates on-chip multiplexed, ultrasensitive, longitudinal cytokine secretion profiling of cultured brain endothelial barrier tissues. The integrated digital sensors utilize a novel beadless microwell format to perform an ultrafast "digital fingerprinting" of the analytes while achieving a low limit of detection (LoD) around 100-500 fg/mL for mouse MCP1 (CCL2), IL-6 and KC (CXCL1). The DigiTACK platform is extensively applicable to profile temporal cytokine secretion of other barrier-related organ-on-a-chip systems and can provide new insight into the secretory dynamics of the BBB by sequentially controlled experiments.

Specific signature biomarkers highlight the potential mechanisms of circulating neutrophils in aneurysmal subarachnoid hemorrhage

Background: Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating hemorrhagic stroke with high disability and mortality. Neuroinflammation and the immunological response after aSAH are complex pathophysiological processes that have not yet been fully elucidated. Therefore, attention should be paid to exploring the inflammation-related genes involved in the systemic response to the rupture of intracranial aneurysms.

Methods: The datasets of gene transcriptomes were downloaded from the Gene Expression Omnibus database. We constructed a gene co-expression network to identify cluster genes associated with aSAH and screened out differentially expressed genes (DEGs). The common gene was subsequently applied to identify hub genes by protein-protein interaction analysis and screen signature genes by machine learning algorithms. CMap analysis was implemented to identify potential small-molecule compounds. Meanwhile, Cibersort and ssGSEA were used to evaluate the immune cell composition, and GSEA reveals signal biological pathways.

Results: We identified 602 DEGs from the GSE36791. The neutrophil-related module associated with aSAH was screened by weighted gene co-expression network analysis (WGCNA) and functional enrichment analysis. Several small molecular compounds were predicted based on neutrophil-related genes. MAPK14, ITGAM, TLR4, and FCGR1A have been identified as crucial genes involved in the peripheral immune activation related to neutrophils. Six significant genes (CST7, HSP90AB1, PADI4, PLBD1, RAB32, and SLAMF6) were identified as signature biomarkers by performing the LASSO analysis and SVM algorithms. The constructed machine learning model appears to be robust by receiver-operating characteristic curve analysis. The immune feature analysis demonstrated that neutrophils were upregulated post-aSAH and PADI4 was positively correlated with neutrophils. The NETs pathway was significantly upregulated in aSAH.

Conclusion: We identified core regulatory genes influencing the transcription profiles of circulating neutrophils after the rupture of intracranial aneurysms using bioinformatics analysis and machine learning algorithms. This study provides new insight into the mechanism of peripheral immune response and inflammation after aSAH.

Longitudinal characterization of circulating neutrophils uncovers phenotypes associated with severity in hospitalized COVID-19 patients

Mechanisms of neutrophil involvement in severe coronavirus disease 2019 (COVID-19) remain incompletely understood. Here, we collect longitudinal blood samples from 306 hospitalized COVID-19+ patients and 86 controls and perform bulk RNA sequencing of enriched neutrophils, plasma proteomics, and high-throughput antibody profiling to investigate relationships between neutrophil states and disease severity. We identify dynamic switches between six distinct neutrophil subtypes. At days 3 and 7 post-hospitalization, patients with severe disease display a granulocytic myeloid-derived suppressor cell-like gene expression signature, while patients with resolving disease show a neutrophil progenitor-like signature. Humoral responses are identified as potential drivers of neutrophil effector functions, with elevated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific immunoglobulin G1 (IgG1)-to-IgA1 ratios in plasma of severe patients who survived. In vitro experiments confirm that while patient-derived IgG antibodies induce phagocytosis in healthy donor neutrophils, IgA antibodies predominantly induce neutrophil cell death. Overall, our study demonstrates a dysregulated myelopoietic response in severe COVID-19 and a potential role for IgA-dominant responses contributing to mortality.

Neutrophil N1 and N2 Subsets and Their Possible Association with Periodontitis: A Scoping Review

Periodontitis is a chronic non-communicable disease caused by dysbiotic changes that affect the subgingival microbiota. During periodontitis, neutrophils play a central role in the initial recognition of bacteria, and their number increases with the appearance of the first signs of periodontal inflammation. Recent evidence has led to the proposition that neutrophils can also functionally polarize, determining selective activity patterns related to different diseases. Two well-defined neutrophil phenotypes have been described, the pro-inflammatory N1 subset and the suppressor N2 subset. To date, it has not been established whether these different neutrophil subtypes play a role in the pathogenesis of periodontitis. Thus, this scoping review aimed to determine whether there was evidence to suggest that the neutrophils present in periodontal tissues can be associated with certain phenotypes. The research question, population, concept, and context sought to identify original articles, in humans, that detected the presence of neutrophils in the periodontal tissues of people affected by periodontitis. Based on the search strategy, we found 3658 studies. After removing the papers with abstracts not related to the outcome measures and eligibility criteria, 16 articles were included for qualitative analysis. Several studies identified the presence of different neutrophil subsets, specifically, the naive, pro- and para-inflammatory, hyper-reactive and hyper-active, and high- and low-responder phenotypes. The existing evidence demonstrates the presence of pro-inflammatory, hyper-reactive and high-responder neutrophils in periodontal tissues affected with periodontitis. There is no evidence demonstrating the presence of the N1 or N2 phenotypes in periodontal tissues during periodontitis. However, the existence of pro-inflammatory phenotypes, which increase NETosis and degranulation, and increase the production of pro-inflammatory cytokines, could be suggestive of the N1 phenotypes.

Experimental Bothrops atrox Envenomation: Blood Plasma Proteome Effects after Local Tissue Damage and Perspectives on Thromboinflammation

The clinical manifestations of Bothrops atrox envenoming involve local and systemic changes, among which edema requires substantial attention due to its ability to progress to compartmental syndromes and sometimes cause tissue loss and amputations. However, the impact of edema on the poisoned body’s system has not been explored. Thus, the present study aimed to explore the systemic pathological and inflammatory events that are altered by intraplantar injection of B. atrox venom in a mouse model through hematologic, lipidic, and shotgun proteomics analysis. Plasma samples collected showed a greater abundance of proteins related to complement, coagulation, lipid system, platelet and neutrophil degranulation, and pathways related to cell death and ischemic tolerance. Interestingly, some proteins, in particular, Prdx2 (peroxiredoxin 2), Hba (hemoglobin subunit alpha), and F9 (Factor IX), increased according to the amount of venom injected. Our findings support that B. atrox venom activates multiple blood systems that are involved in thromboinflammation, an observation that may have implications for the pathophysiological progression of envenomations. Furthermore, we report for the first time a potential role of Prdx2, Hba, and F9 as potential markers of the severity of edema/inflammation in mice caused by B. atrox.

High-CBD Extract (CBD-X) Downregulates Cytokine Storm Systemically and Locally in Inflamed Lungs

Cytokine storm refers to the dysregulated production of inflammatory mediators leading to hyperinflammation. They are often detrimental, and worsen the severity of COVID-19 and other infectious or inflammatory diseases. Cannabinoids are known to have anti-inflammatory effects but their possible therapeutic value on cytokine storms has not been fully elucidated. In vivo and ex vivo studies were carried out to investigate the effects of high-THC and high-CBD extracts on cytokine production in immune cells. Significant differences between the extracts were observed. Subsequent experiments focusing on a specific high CBD extract (CBD-X) showed significant reductions in pro-inflammatory cytokines in human-derived PBMCs, neutrophils and T cells. In vivo mouse studies, using a systemically inflamed mouse model, showed reductions in pro-inflammatory cytokines TNFα and IL-1β and a concurrent increase in the anti-inflammatory cytokine IL-10 in response to CBD-X extract treatment. Lung inflammation, as in severe COVID-19 disease, is characterized by increased T-cell homing to the lungs. Our investigation revealed that CBD-X extract impaired T-cell migration induced by the chemoattractant SDF1. In addition, the phosphorylation levels of T cell receptor (TCR) signaling proteins Lck and Zap70 were significantly reduced, demonstrating an inhibitory effect on the early events downstream to TCR activation. In a lung inflamed mouse model, we observed a reduction in leukocytes including neutrophil migration to the lungs and decreased levels of IL-1β, MCP-1, IL-6 and TNFα, in response to the administration of the high-CBD extract. The results presented in this work offer that certain high-CBD extract has a high potential in the management of pathological conditions, in which the secretion of cytokines is dysregulated, as it is in severe COVID-19 disease or other infectious or inflammatory diseases.

Myeloid Poldip2 Contributes to the Development of Pulmonary Inflammation by Regulating Neutrophil Adhesion in a Murine Model of Acute Respiratory Distress Syndrome

Background Lung injury, a severe adverse outcome of lipopolysaccharide-induced acute respiratory distress syndrome, is attributed to excessive neutrophil recruitment and effector response. Poldip2 (polymerase δ-interacting protein 2) plays a critical role in regulating endothelial permeability and leukocyte recruitment in acute inflammation. Thus, we hypothesized that myeloid Poldip2 is involved in neutrophil recruitment to inflamed lungs. Methods and Results After characterizing myeloid-specific Poldip2 knockout mice, we showed that at 18 hours post-lipopolysaccharide injection, bronchoalveolar lavage from myeloid Poldip2-deficient mice contained fewer inflammatory cells (8 [4-16] versus 29 [12-57]×10⁴/mL in wild-type mice) and a smaller percentage of neutrophils (30% [28%-34%] versus 38% [33%-41%] in wild-type mice), while the main chemoattractants for neutrophils remained unaffected. In vitro, Poldip2-deficient neutrophils responded as well as wild-type neutrophils to inflammatory stimuli with respect to neutrophil extracellular trap formation, reactive oxygen species production, and induction of cytokines. However, neutrophil adherence to a tumor necrosis factor-α stimulated endothelial monolayer was inhibited by Poldip2 depletion (225 [115-272] wild-type [myePoldip2^+/+] versus 133 [62-178] myeloid-specific Poldip2 knockout [myePoldip2^-/-] neutrophils) as was transmigration (1.7 [1.3-2.1] versus 1.1 [1.0-1.4] relative to baseline transmigration). To determine the underlying mechanism, we examined the surface expression of β2-integrin, its binding to soluble intercellular adhesion molecule 1, and Pyk2 phosphorylation. Surface expression of β2-integrins was not affected by Poldip2 deletion, whereas β2-integrins and Pyk2 were less activated in Poldip2-deficient neutrophils. Conclusions These results suggest that myeloid Poldip2 is involved in β2-integrin activation during the inflammatory response, which in turn mediates neutrophil-to-endothelium adhesion in lipopolysaccharide-induced acute respiratory distress syndrome.

The Age-Driven Decline in Neutrophil Function Contributes to the Reduced Efficacy of the Pneumococcal Conjugate Vaccine in Old Hosts

Despite the availability of vaccines, Streptococcus pneumoniae (pneumococcus) remains a serious cause of infections in the elderly. The efficacy of anti-pneumococcal vaccines declines with age. While age-driven changes in antibody responses are well defined, less is known about the role of innate immune cells such as polymorphonuclear leukocytes (PMNs) in the reduced vaccine protection seen in aging. Here we explored the role of PMNs in protection against S. pneumoniae in vaccinated hosts. We found that depletion of PMNs in pneumococcal conjugate vaccine (PCV) treated young mice prior to pulmonary challenge with S. pneumoniae resulted in dramatic loss of host protection against infection. Immunization boosted the ability of PMNs to kill S. pneumoniae and this was dependent on bacterial opsonization by antibodies. Bacterial opsonization with immune sera increased several PMN anti-microbial activities including bacterial uptake, degranulation and ROS production. As expected, PCV failed to protect old mice against S. pneumoniae. In probing the role of PMNs in this impaired protection, we found that aging was accompanied by an intrinsic decline in PMN function. PMNs from old mice failed to effectively kill S. pneumoniae even when the bacteria were opsonized with immune sera from young controls. In exploring mechanisms, we found that PMNs from old mice produced less of the antimicrobial peptide CRAMP and failed to efficiently kill engulfed pneumococci. Importantly, adoptive transfer of PMNs from young mice reversed the susceptibility of vaccinated old mice to pneumococcal infection. Overall, this study demonstrates that the age-driven decline in PMN function impairs vaccine-mediated protection against Streptococcus pneumoniae.

A fingerprint of plasma proteome alteration after local tissue damage induced by Bothrops leucurus snake venom in mice

Bothrops spp. is responsible for about 70% of snakebites in Brazil, causing a diverse and complex pathophysiological condition. Bothrops leucurus is the main species of medical relevance found in the Atlantic coast in the Brazilian Northeast region. The pathophysiological effects involved B. leucurus snakebite as well as the organism's reaction in response to this envenoming, it has not been explored yet. Thus, edema was induced in mice paw using 1.2, 2.5, and 5.0 μg of B. leucurus venom, the percentage of edema was measured 30 min after injection and the blood plasma was collected and analyzed by shotgun proteomic strategy. We identified 80 common plasma proteins with differential abundance among the experimental groups and we can understand the early aspects of this snake envenomation, regardless of the suggestive severity of an ophidian accident. The results showed B. leucurus venom triggers a thromboinflammation scenario where family's proteins of the Serpins, Apolipoproteins, Complement factors and Component subunits, Cathepsins, Kinases, Oxidoreductases, Proteases inhibitors, Proteases, Collagens, Growth factors are related to inflammation, complement and coagulation systems, modulators platelets and neutrophils, lipid and retinoid metabolism, oxidative stress and tissue repair. Our findings set precedents for future studies in the area of early diagnosis and/or treatment of snakebites. SIGNIFICANCE: The physiopathological effects that the snake venoms can cause have been investigated through classical and reductionist tools, which allowed, so far, the identification of action mechanisms of individual components associated with specific tissue damage. The currently incomplete limitations of this knowledge must be expanded through new approaches, such as proteomics, which may represent a big leap in understanding the venom-modulated pathological process. The exploration of the complete protein set that suffer modifications by the simultaneous action of multiple toxins, provides a map of the establishment of physiopathological phenotypes, which favors the identification of multiple toxin targets, that may or may not act in synergy, as well as favoring the discovery of biomarkers and therapeutic targets for manifestations that are not neutralized by the antivenom.

Sambucus nigra: A traditional medicine effective in reducing inflammation in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Sambucus nigra L. is a plant of European origin and popularly known as elder, elderberry, black elder, European elder, European elderberry, and European black elderberry, being described in pharmacopoeia of several countries. Its flowers and berries have been used in folk medicine to treat feverish conditions, coughing, nasal congestion, and influenza besides its popular use as anti-inflammatory, analgesic, and diuretic agent.

AIM OF THE STUDY

The aim of this investigation was to elucidate the anti-inflammatory and the relaxant effect of the lyophilized aqueous extract obtained from S. nigra's flowers on in vivo and in vitro inflammation assays and on the isolated rat vascular and airway smooth muscle tissue.

MATERIAL AND METHODS

The anti-inflammatory activity of the extract was investigated using carrageenan-induced inflammation model in the subcutaneous tissue of male Swiss mice orally treated with S. nigra extract (30, 100, 300 or 600 mg/kg). Leukocyte influx and the secretion of chemical mediators were quantified in the inflamed exudate. Additionally, histological analysis of the pouches was performed. N-Formyl-methionine-leucine-phenylalanine-induced chemotaxis, lipopolysaccharide-induced TNF, IL-6, IL-1β, IL-10 and NO production, and adhesion molecule expression (CD62L, CD49d and CD18, flow cytometry) were analyzed in vitro using oyster glycogen-recruited peritoneal neutrophils or macrophages (RAW 264.7) stimulated with LPS and treated with the extract (1, 10 or 100 μg/mL). The resolution of inflammation was accessed by efferocytosis assay, and the antinociceptive activity was investigated using carrageenan-induced mechanical hypersensitivity. Finally, the effect of the extract was evaluated in isolated rat aorta and trachea rings.

RESULTS

The oral treatment with S. nigra promoted reduction in the neutrophil migration as well as the decrease of TNF, IL-1β and IL-6 levels in the inflamed exudate. In vitro treatment with S. nigra decreased NO₂^-, TNF, IL-1β and IL-6 and promoted increase of IL-10 in LPS-stimulated neutrophils. Similarly, the extract reduced the NO₂^-, TNF and IL-6 in LPS-stimulated macrophages. Rutin, the major constituent of S. nigra extract reduced NO₂^-, TNF, IL-1β, and IL-6 and promoted the increase of IL-10 in LPS-stimulated neutrophils supernatant. The extract also shed CD62L and CD18 expressions. The extract was able to increase the efferocytosis of apoptotic neutrophils by increasing the IL-10 and decreasing the TNF levels. Additionally, the extract reduced the hypersensitivity induced by carrageenan and promoted a relaxant effect in isolated vascular and non-vascular rat tissue.

CONCLUSIONS

S. nigra flowers extract presents anti-inflammatory effect by modulating macrophage and neutrophil functions including the production of inflammatory mediators and cell migration, by promoting efferocytosis and consequently the resolution of acute inflammation, besides exerting antinociceptive effects, scientifically proving its popular use as medicinal plant. Allied to the relaxant effect in both vascular and non-vascular smooth muscle tissue, S. nigra extract represents an important tool for the management of acute inflammation.

Patterns of Maternal Neutrophil Gene Expression at 30 Weeks of Gestation, but Not DNA Methylation, Distinguish Mild from Severe Preeclampsia

Neutrophils are activated and extensively infiltrate blood vessels in preeclamptic women. To identify genes that contribute to neutrophil activation and infiltration, we analyzed the transcriptomes of circulating neutrophils from normal pregnant and preeclamptic women. Neutrophils were collected at 30 weeks’ gestation and RNA and DNA were isolated for RNA sequencing and 5-hydroxy-methylcytosine (5-hmC) sequencing as an index of dynamic changes in neutrophil DNA methylation. Women with normal pregnancy who went on to develop mild preeclampsia at term had the most uniquely expressed genes (697) with 325 gene ontology pathways upregulated, many related to neutrophil activation and function. Women with severe preeclampsia who delivered prematurely had few pathways up- or downregulated. Cluster analysis revealed that gene expression in women with severe preeclampsia was an inverse mirror image of gene expression in normal pregnancy, while gene expression in women who developed mild preeclampsia was remarkably different from both. DNA methylation marks, key regulators of gene expression, are removed by the action of ten-eleven translocation (TET) enzymes, which oxidize 5-methylcytosines (5mCs), resulting in locus-specific reversal of DNA methylation. DNA sequencing for 5-hmC revealed no differences among the three groups. Genome-wide DNA methylation revealed extremely low levels in circulating neutrophils suggesting they are de-methylated. Collectively, these data demonstrate that neutrophil gene expression profiles can distinguish different preeclampsia phenotypes, and in the case of mild preeclampsia, alterations in gene expression occur well before clinical symptoms emerge. These findings serve as a foundation for further evaluation of neutrophil transcriptomes as biomarkers of preeclampsia phenotypes. Changes in DNA methylation in circulating neutrophils do not appear to mediate differential patterns of gene expression in either mild or severe preeclampsia.

Tumor-Derived Factors Differentially Affect the Recruitment and Plasticity of Neutrophils

Neutrophils play a key role in cancer biology. In contrast to circulating normal-density neutrophils (NDN), the amount of low-density neutrophils (LDN) significantly increases with tumor progression. The correlation between these neutrophil subpopulations and intratumoral neutrophils (TANs) is still under debate. Using 4T1 (breast) and AB12 (mesothelioma) tumor models, we aimed to elucidate the source of TANs and to assess the mechanisms driving neutrophils' plasticity in cancer. Both NDN and LDN were found to migrate in response to CXCL1 and CXCL2 exposure, and co-infiltrate the tumor site ex vivo and in vivo, although LDN migration into the tumor was higher than NDN. Tumor-derived factors and chemokines, particularly CXCL1, were found to drive neutrophil phenotypical plasticity, inducing NDN to transition towards a low-density state (LD-NDN). LD-NDN appeared to differ from NDN by displaying a phenotypical profile similar to LDN in terms of nuclear morphology, surface receptor markers, decreased phagocytic abilities, and increased ROS production. Interestingly, all three subpopulations displayed comparable cytotoxic abilities towards tumor cells. Our data suggest that TANs originate from both LDN and NDN, and that a portion of LDN derives from NDN undergoing phenotypical changes. NDN plasticity resulted in a change in surface marker expression and functional activity, gaining characteristics of LDN.

Plaque erosion and acute coronary syndromes: phenotype, molecular characteristics and future directions

Although acute coronary syndromes (ACS) remain one of the leading causes of death, the clinical presentation has changed over the past three decades with a decline in the incidence of ST-segment elevation myocardial infarction (STEMI) and an increase in non-STEMI. This epidemiological shift is at least partially explained by changes in plaque biology as a result of the widespread use of statins. Historically, atherosclerotic plaque rupture of the fibrous cap was thought to be the main culprit in ACS. However, plaque erosion with an intact fibrous cap is now responsible for about one third of ACS and up to two thirds of non-STEMI. Two major research approaches have enabled a better understanding of plaque erosion. First, advanced intravascular imaging has provided opportunities for an 'optical biopsy' and extensive phenotyping of coronary plaques in living patients. Second, basic science experiments have shed light on the unique molecular characteristics of plaque erosion. At present, patients with ACS are still uniformly treated with coronary stents irrespective of the underlying pathobiology. However, pilot studies indicate that patients with plaque erosion might be treated conservatively without coronary stenting. In this Review, we discuss the patient phenotype and the molecular characteristics in atherosclerotic plaque erosion and provide our vision for a potential major shift in the management of patients with plaque erosion.

Hyperbaric oxygen treatment impacts oxidative stress markers in patients with necrotizing soft-tissue infection

Necrotizing soft-tissue infection (NSTI) is a rare, severe, and fast-progressing bacterial infection associated with a high risk of developing sepsis or septic shock. Increasing evidence indicates that oxidative stress is crucial in the development and progression of sepsis, but its role in NSTI specifically has not been investigated. Some patients with NSTI receive hyperbaric oxygen (HBO₂) treatment as the restoration of oxidative stress balance is considered an important mechanism of action, which HBO₂ facilitates. However, a gap in knowledge exists regarding the effect of HBO₂ treatment on oxidative stress in patients with NSTI. In the present observational study, we aimed to investigate HBO₂ treatment effects on known markers of oxidative stress in patients with NSTI. We measured plasma myeloperoxidase (MPO), superoxide dismutase (SOD), heme oxygenase-1 (HO-1) and nitrite+nitrate in 80 patients with NSTI immediately before and after their first HBO₂ treatment, and on the following day. We found that HBO₂ treatment was associated with a significant increase in MPO and SOD by a median of 3.4 and 8.8 ng/mL, respectively. Moreover, we observed an HBO₂ treatment-associated increase in HO-1 in patients presenting with septic shock (n=39) by a median of 301.3 pg/mL. All markers were significantly higher in patients presenting with septic shock compared to patients without shock, and all markers correlated with disease severity. High baseline SOD was associated with 90-day mortality. In conclusion, HBO₂ treatment was associated with an increase in MPO and SOD in patients with NSTI, and oxidative stress was more pronounced in patients with septic shock.

Multiplexed Single-Cell Leukocyte Enzymatic Secretion Profiling from Whole Blood Reveals Patient-Specific Immune Signature

Enzymatic secretion of immune cells (leukocytes) plays a dominant role in host immune responses to a myriad of biological triggers, including infections, cancers, and cardiovascular diseases. Current tools to probe these leukocytes inadequately profile these vital biomarkers; the need for sample preprocessing steps of cell lysis, labeling, washing, and pipetting inevitably triggers the cells, changes its basal state, and dilutes the individual cell secretion in bulk assays. Using a fully integrated system for multiplexed profiling of native immune single-cell enzyme secretion from 50 μL of undiluted blood, we eliminate sample handling. With a total analysis time of 60 min, the integrated platform performs six tasks of leukocyte extraction, cell washing, fluorescent enzyme substrate mixing, single-cell droplet making, droplet incubation, and real-time readout for leukocyte secretion profiling of neutrophil elastase, granzyme B, and metalloproteinase. We calibrated the device, optimized the protocols, and tested the leukocyte secretion of acute heart failure (AHF) patients at admission and predischarge. This paper highlights the presence of single-cell enzymatic immune phenotypes independent of CD marker labeling, which could potentially elucidate the innate immune response states. We found that patients recovering from AHF showed a corresponding reduction in immune-cell enzymatic secretion levels and donor-specific enzymatic signatures were observed, which suggests patient-to-patient heterogeneous immune response. This platform presents opportunities to elucidate the complexities of the immune response from a single drop of blood and bridge the current technological, biological, and medical gap in understanding immune response and biological triggers.

S100A11 (calgizzarin) is released via NETosis in rheumatoid arthritis (RA) and stimulates IL-6 and TNF secretion by neutrophils

S100A11 (calgizzarin), a member of S100 family, is associated with several autoimmune diseases, including rheumatoid arthritis (RA). Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of RA and in the externalization of some S100 family members. Therefore, we aimed to determine the association between S100A11 and NETs in RA. For this purpose, the levels of S100A11 and NETosis markers were detected in the RA synovial fluid by immunoassays. The expression of S100A11 by neutrophils in the RA synovial tissue was assessed. Neutrophils isolated from peripheral blood were exposed to S100A11 or stimulated to release NETs. The levels of NETosis- and inflammation-associated proteins were analysed by immunoassays. NETs were visualized by immunofluorescence. We showed that S100A11 was expressed by the neutrophils in the RA synovial tissue. Moreover, S100A11 in the RA synovial fluid correlated with several NETosis markers. In vitro, S100A11 was abundantly released by neutrophils undergoing NETosis compared to untreated cells (p < 0.001). Extracellular S100A11 increased the secretion of IL-6 (p < 0.05) and TNF (p < 0.05) by neutrophils but did not induce NETosis. This study demonstrates, for the first time, that the release of S100A11 is dependent on NETosis and that extracellular S100A11 augments the inflammatory response by inducing pro-inflammatory cytokines in neutrophils.

Whole genomes reveal multiple candidate genes and pathways involved in the immune response of dolphins to a highly infectious virus

Wildlife species are challenged by various infectious diseases that act as important demographic drivers of populations and have become a great conservation concern particularly under growing environmental changes. The new era of whole genome sequencing provides new opportunities and avenues to explore the role of genetic variants in the plasticity of immune responses, particularly in non-model systems. Cetacean morbillivirus (CeMV) has emerged as a major viral threat to cetacean populations worldwide, contributing to the death of thousands of individuals of multiple dolphin and whale species. To understand the genomic basis of immune responses to CeMV, we generated and analysed whole genomes of 53 Indo-Pacific bottlenose dolphins (Tursiops aduncus) exposed to Australia's largest known CeMV-related mortality event that killed at least 50 dolphins from three different species. The genomic data set consisted of 10,168,981 SNPs anchored onto 23 chromosome-length scaffolds and 77 short scaffolds. Whole genome analysis indicated that levels of inbreeding in the dolphin population did not influence the outcome of an individual. Allele frequency estimates between survivors and nonsurvivors of the outbreak revealed 15,769 candidate SNPs, of which 689 were annotated to 295 protein coding genes. These included 50 genes with functions related to innate and adaptive immune responses, and cytokine signalling pathways and genes thought to be involved in immune responses to other morbilliviruses. Our study characterised genomic regions and pathways that may contribute to CeMV immune responses in dolphins. This represents a stride towards clarifying the complex interactions of the cetacean immune system and emphasises the value of whole genome data sets in understanding genetic elements that are essential for species conservation, including disease susceptibility and adaptation.

Chitosan and Lecithin Ameliorate Osteoarthritis Symptoms Induced by Monoiodoacetate in a Rat Model

The present work aimed to assess the chondroprotective influence of chitosan and lecithin in a monoiodoacetate (MIA)-induced experimental osteoarthritis (OA) model. Forty male rats weighing 180–200 g were randomly distributed among the following five experimental groups (eight per group): control, MIA-induced OA, MIA-induced OA + chitosan, MIA-induced OA + lecithin, and MIA-induced OA + chitosan + lecithin. The levels of TNF-α, IL6, RF, ROS, and CRP, as well as mitochondrial markers such as mitochondrial swelling, cytochrome C oxidase (complex IV), MMP, and serum oxidative/antioxidant status (MDA level) (MPO and XO activities) were elevated in MIA-induced OA. Also, SDH (complex II) activity in addition to the levels of ATP, glutathione (GSH), and thiol was markedly diminished in the MIA-induced OA group compared to in control rats. These findings show that mitochondrial function is associated with OA pathophysiology and suggest that chitosan and lecithin could be promising potential ameliorative agents in OA animal models. Lecithin was more effective than chitosan in ameliorating all of the abovementioned parameters.

The main bioactive compounds of Scutellaria baicalensis Georgi. for alleviation of inflammatory cytokines: A comprehensive review

Scutellaria baicalensis Georgi., a plant used in traditional Chinese medicine, has multiple biological activities, including anti-inflammatory, antiviral, antitumor, antioxidant, and antibacterial effects, and can be used to treat respiratory tract infections, pneumonia, colitis, hepatitis, and allergic diseases. The main active substances of S. baicalensis, baicalein, baicalin, wogonin, wogonoside, and oroxylin A, can act directly on immune cells such as lymphocytes, macrophages, mast cells, dendritic cells, monocytes, and neutrophils, and inhibit the production of the inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α, and other inflammatory mediators such as nitric oxide, prostaglandins, leukotrienes, and reactive oxygen species. The molecular mechanisms underlying the immunomodulatory and anti-inflammatory effects of the active compounds of S. baicalensis include downregulation of toll-like receptors, activation of the Nrf2 and PPAR signaling pathways, and inhibition of the nuclear thioredoxin system and inflammation-associated pathways such as those of MAPK, Akt, NFκB, and JAK-STAT. Given that in addition to the downregulation of cytokine production, the active constituents of S. baicalensis also have antiviral and antibacterial effects, they may be more promising candidate therapeutics for the prevention of infection-related cytokine storms than are drugs having only antimicrobial or anti-inflammatory activities.

Pirfenidone regulates LPS mediated activation of neutrophils

Excessive inflammation or its absence may result in impaired wound healing. Neutrophils are among the first innate immune cells to arrive at the injury site. They participate in infection control and debris removal to initiate healing. If not timely resolved, neutrophils can cause excessive tissue inflammation and damage. Drugs with anti-inflammatory and anti-fibrotic effects are of promise for improving healing by balancing the primary defensive functions and excessive tissue damage actions. Of interest, pirfenidone (Pf), an FDA approved anti-fibrotic drug to treat idiopathic pulmonary fibrosis, has been shown to ameliorate inflammation in several animal models including mouse deep partial-thickness burn wounds. However, there is a lack of mechanistic insights into Pf drug action on inflammatory cells such as neutrophils. Here, we examined the treatment effects of Pf on LPS-stimulated neutrophils as a model of non-sterile inflammation. Firstly, Pf reduced chemotaxis and production of pro-inflammatory ROS, cytokines, and chemokines by LPS-activated neutrophils. Secondly, Pf increased anti-inflammatory IL-1RA and reduced neutrophil degranulation, phagocytosis, and NETosis. Thirdly, Pf affected downstream signaling kinases which might directly or indirectly influence neutrophil responses to LPS. In conclusion, the results suggest that Pf lessens the inflammatory phenotypes of LPS-activated neutrophils.

Human neutrophils compromise the restoration-tooth interface

Neutrophils, cells of the innate immune system, enter the mouth and release factors that are hypothesized to contribute to the degradation of tooth dentin, methacrylate resin composites, and adhesives at the restoration-tooth-dentin interface. The objectives were to characterize neutrophils' degradation towards resin composite, self-etch (SE) and total-etch (TE) adhesives, SE and TE resin-dentin interfaces and to identify proteins that could contribute to the degradation process. Neutrophils' degradation of cured resin composite, and SE and TE adhesives, was quantified by measuring the specific resin degradation by-product, bishydroxy-propoxy-phenyl-propane (bisHPPP), released after 30 days incubation of the materials with the cells. Neutrophils' degradative effect on resin-dentin interfaces was examined by recording the interfacial fracture toughness (FT), and surface analysis of the fracture mode following incubation of SE and TE miniature short-rod (mini-SR) specimens with the cells. Neutrophils increased degradation of polymerized resin composite, and TE adhesive, but not SE adhesive over 30 days (p < 0.05). Incubation of SE and TE resin-dentin interfaces with neutrophils led to a reduction in FT over time (p < 0.05). The effect was more pronounced for TE interfaces. Neutrophils also affected the fracture mode of SE and TE resin-dentin interfaces. Several proteins that could contribute to the degradative activity of neutrophils, including Neutrophil collagenase (MMP-8), Matrix metalloproteinase- 9 (MMP-9), Cathepsin G, Neutrophil- gelatinase associated lipocalin (NGAL) and Myeloperoxidase, were isolated. The ability of neutrophils to degrade resin, tooth dentin, and reduce the bond strength of resin-dentin interfaces suggest neutrophils' potential role in primary and recurrent caries and dental restoration failure.

Src kinase inhibition with dasatinib impairs neutrophil function and clearance of Escherichia coli infection in a murine model of acute lung injury

BACKGROUND

Neutrophils rapidly respond to and clear infection from tissues, but can also induce tissue damage through excessive degranulation, when acute inflammation proceeds unchecked. A number of key neutrophil functions, including adhesion-dependent degranulation, are controlled by src family kinases. Dasatinib is a potent src inhibitor used in treating patients with chronic myeloid leukaemia and treatment-resistant acute lymphoblastic leukaemia. We hypothesized that dasatinib would attenuate acute inflammation by inhibiting neutrophil recruitment, degranulation and endothelial cell injury, without impairing bacterial clearance, in a murine model of bacteria-induced acute lung injury. C57BL/6 mice received intratracheal Escherichia coli, and were treated with intraperitoneal dasatinib or control. Bacterial clearance, lung injury, and markers of neutrophil recruitment and degranulation were measured. Separately, human blood neutrophils were exposed to dasatinib or control, and the effects on a range of neutrophil functions assessed.

RESULTS

Dasatinib was associated with a dose-dependent significant increase in E. coli in the mouse lung, accompanied by impairment of organ function, reflected in significantly increased protein leak across the alveolar-capillary membrane. However, the number of neutrophils entering the lung was unaffected, suggesting that dasatinib impairs neutrophil function independent of migration. Dasatinib did not cause direct toxicity to human neutrophils, but led to significant reductions in phagocytosis of E. coli, adhesion, chemotaxis, generation of superoxide anion and degranulation of primary and secondary granules. However, no biologically important effect of dasatinib on neutrophil degranulation was observed in mice.

CONCLUSIONS

Contrary to our starting hypothesis, src kinase inhibition with dasatinib had a detrimental effect on bacterial clearance in the mouse lung and therefore does not represent an attractive therapeutic strategy to treat primary infective lung inflammation. Data from human neutrophils suggest that dasatanib has inhibitory effects on a range of neutrophil functions.

Neutrophil fluorescence in clozapine users is attributable to a 14kDa secretable protein

Clozapine is the only antipsychotic agent with demonstrated efficacy in refractory schizophrenia. However, use of clozapine is hampered by its adverse effects, including potentially fatal agranulocytosis. Recently, we showed an association between neutrophil autofluorescence and clozapine use. In this study, we evaluated the subcellular localization of clozapine-associated fluorescence and tried to elucidate its source. Neutrophils of clozapine users were analyzed with fluorescence microscopy to determine the emission spectrum and localization of the fluorescence signal. Next, these neutrophils were stimulated with different degranulation agents to determine the localization of fluorescence. Lastly, isolated neutrophil lysates of clozapine users were separated by SDS-PAGE and evaluated. Clozapine-associated fluorescence ranged from 420 nm to 720 nm, peaking at 500-550 nm. Fluorescence was localized in a large number of small loci, suggesting granular localization of the signal. Neutrophil degranulation induced by Cytochalasin B/fMLF reduced fluorescence, whereas platelet-activating factor (PAF)/fMLF induced degranulation did not, indicating that the fluorescence originates from a secretable substance in azurophilic granules. SDS-PAGE of isolated neutrophil lysates revealed a fluorescent 14kDa band, suggesting that neutrophil fluorescence is likely to be originated from a 14kDa protein/peptide fragment. We conclude that clozapine-associated fluorescence in neutrophils is originating from a 14kDa soluble protein (fragment) present in azurophilic granules of neutrophils. This protein could be an autofluorescent protein already present in the cell and upregulated by clozapine, or a protein altered by clozapine to express fluorescence. Future studies should further explore the identity of this protein and its potential role in the pathophysiology of clozapine-induced agranulocytosis.

Mechanism of Nanoformulated Graphene Oxide-Mediated Human Neutrophil Activation

Understanding the molecular mechanisms of graphene oxide (GO)-based biomaterials is important for logical biomedical applications. Previous studies have revealed biointeractions between GO and immune effector cells, but the effects on neutrophils, crucial cells in the immune system, have not been thoroughly discussed. In this study, GO nanoformulations were synthesized with different functional groups, including GO, GO-carboxylated (GO-COOH), and PEGylated GO (GO-PEG), with different surface features, which were elucidated using imaging methods and surface-sensitive quantitative spectroscopic techniques, including atomic force microscopy (AFM), transmission electron microscopy (TEM), and X-ray photoemission spectroscopy (XPS). The GO-based nanoformulations elicited reactive oxygen species (ROS) generation and neutrophil extracellular trap (NET) formation in human neutrophils. Nanoformulated GO stimulates NET development via the formation of ROS. An endocytosis study revealed that nanoformulated GO facilitated internalization by neutrophils via macropinocytosis and actin-dependent phagocytosis. Importantly, calcium mobilization and phosphorylation proteins such as mitogen-activated protein kinases (extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38) and AKT were involved in the activation of neutrophils. These findings offer the first verification that nanoformulated GO exhibits direct effects on human neutrophils.

Synthesis of N,N'-bis(1,5-dimethyl-2-phenyl-1,2-dihydro-3-oxopyrazol-4-yl) sebacamide that ameliorate osteoarthritis symptoms and improve bone marrow matrix structure and cartilage alterations induced by monoiodoacetate in the rat model: "Suggested potent anti-inflammatory agent against COVID-19"

To assess the chondroprotective effect and influence of N,N′-bis(1,5-dimethyl-2-phenyl-1,2-dihydro-3-oxopyrazol-4-yl) sebacamide (dpdo) that was synthesized through the reaction of phenazone with sebacoyl chloride and screened for its biological activity especially as anti-arthritic and anti-inflammatory agent in a monoiodoacetate (MA)-induced experimental osteoarthritis (OA) model. Thirty male albino rats weighing “190–200 g” were divided randomly into three groups (10 each): control, MA-induced OA, and MA-induced OA + dpdo. In MA-induced OA rat, the tumor necrosis factor alpha, interleukin 6, C-reactive protein, rheumatoid factors, reactive oxygen species, as well as all the mitochondrial markers such as mitochondria membrane potential, swelling mitochondria, cytochrome c oxidase (complex IV), and serum oxidative/antioxidant status (malondialdehyde level and activities of myeloperoxidase and xanthine oxidase) are elevated. Also, the activity of succinate dehydrogenase (complex II), levels of ATP, the level of glutathione (GSH), and thiol were markedly diminished in the MA-induced OA group compared to the normal control rats. These findings showed that mitochondrial function is associated with OA pathophysiological alterations and high gene expressions of (IL-6, TNF-a, and IL-1b) and suggests a promising use of dpdo as potential ameliorative agents in the animal model of OA and could act as anti-inflammatory agent in case of severe infection with COVID-19. It is clearly appeared in improving the bone cortex and bone marrow in the treated group with the novel compound in histological and transmission electron microscopic sections which is a very important issue today in fighting severe infections that have significant effects on the blood indices and declining of blood corpuscles like COVID-19, in addition to declining the genotoxicity and inflammation induced by MA in male rats. The novel synthesized compound was highly effective in improving all the above mentioned parameters.

Structural and functional diversity of neutrophil glycosylation in innate immunity and related disorders

The granulated neutrophils are abundant innate immune cells that utilize bioactive glycoproteins packed in cytosolic granules to fight pathogenic infections, but the neutrophil glycobiology remains poorly understood. Facilitated by technological advances in glycoimmunology, systems glycobiology and glycoanalytics, a considerable body of literature reporting on novel aspects of neutrophil glycosylation has accumulated. Herein, we summarize the building knowledge of the structural and functional diversity displayed by N- and O-linked glycoproteins spatiotemporally expressed and sequentially brought-into-action across the diverse neutrophil life stages during bone marrow maturation, movements to, from and within the blood circulation and microbicidal processes at the inflammatory sites in peripheral tissues. It transpires that neutrophils abundantly decorate their granule glycoproteins including neutrophil elastase, myeloperoxidase and cathepsin G with peculiar glyco-signatures not commonly reported in other areas of human glycobiology such as hyper-truncated chitobiose core- and paucimannosidic-type N-glycans and monoantennary complex-type N-glycans. Sialyl Lewis^x, Lewis^x, poly-N-acetyllactosamine extensions and core 1-/2-type O-glycans are also common neutrophil glyco-signatures. Granule-specific glycosylation is another fascinating yet not fully understood feature of neutrophils. Recent literature suggests that unconventional biosynthetic pathways and functions underpin these prominent neutrophil-associated glyco-phenotypes. The impact of glycosylation on key neutrophil effector functions including extravasation, degranulation, phagocytosis and formation of neutrophil extracellular traps during normal physiological conditions and in innate immune-related diseases is discussed. We also highlight new technologies that are expected to further advance neutrophil glycobiology and briefly discuss the untapped diagnostic and therapeutic potential of neutrophil glycosylation that could open avenues to combat the increasingly prevalent innate immune disorders.

Innate Immune Defense Mechanisms by Myeloid Cells That Hamper Cancer Immunotherapy

Over the past decade, cancer immunotherapy has been steering immune responses toward cancer cell eradication. However, these immunotherapeutic approaches are hampered by the tumor-promoting nature of myeloid cells, including monocytes, macrophages, and neutrophils. Despite the arsenal of defense strategies against foreign invaders, myeloid cells succumb to the instructions of an established tumor. Interestingly, the most primordial defense responses employed by myeloid cells against pathogens, such as complement activation, antibody-dependent cell cytotoxicity and phagocytosis, actually seem to favor cancer progression. In this review, we discuss how rudimentary defense mechanisms deployed by myeloid cells can promote tumor progression.

Effects of 2',6'-dihydroxy-4'-methoxydihidrochalcone on innate inflammatory response

Chalcones present potential therapeutic activities reported on literature, which led us to evaluate the anti-inflammatory effects and the acute toxicity of 2',6'-dihydroxy-4'-methoxydihydrochalcone (DHMDC) using in vitro and in vivo models. The anti-inflammatory activity was firstly in vitro investigated using macrophages (RAW 264.7) and neutrophils previously treated with DHMCD activated with lipopolysaccharide (LPS). Nitrite, IL-1β, and TNF levels were measured in the macrophage culture supernatant, and the adhesion molecule expression (CD62L, CD49D, and CD18) was evaluated in neutrophils. Then, carrageenan-induced inflammation was performed in the subcutaneous tissue of male Swiss mice. Leukocyte migration and histological analysis were performed in the pouches. Toxicological studies were carried out on female Swiss mice (600 mg/kg) through biochemical parameters and histopathological analysis. In vitro, the DHMCD significantly reduced the IL-1β, TNF, and nitrite levels. The DHMCD was also able to modulate the percentage of positive neutrophils for CD62L, without modifying the expression of CD18 or CD49d. In vivo, DHMCD (3 mg/kg, p.o.) significantly reduced neutrophil migration to inflammatory exudate and subcutaneous tissue. No evidence of toxic effect was observed considering the biochemical parameters and histopathological analysis of liver and kidney. Together, the obtained data shows that DHMCD presents anti-inflammatory activity by modulating the macrophage inflammatory protein secretion and also by blocking the CD62L cleavage in neutrophils. Furthermore, there was not any evidence of toxic effect in acute toxicological analysis.

IL8 and PMA Trigger the Regulation of Different Biological Processes in Granulocyte Activation

The molecular mechanisms driving specific regulation of neutrophils are not completely understood to date. In order to characterize fundamental granulocyte features on protein level, we analyzed changes in proteome composition as reaction to stress from cell activation processes. For this purpose, we isolated primary granulocytes from equine whole blood through density gradient centrifugation followed by sodium chloride lysis and stimulated cells for 30 min with interleukin-8 (IL8) due to its role as a chemotactic factor for neutrophils. We additionally used phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS), which are primarily associated to neutrophil extracellular trap formation and release of reactive oxygen species. From mass spectrometry analysis, we identified a total of 2,032 proteins describing the whole granulocyte proteome, including 245 proteins (12% of identified proteome) newly associated to in vivo expression in primary equine granulocytes (hypothetical proteins). We also found distinct and different changes in protein abundance (ratio ≥ 2) after short stimulation of cells with various stimuli, pointing to rapid and differentiated reaction pattern. IL8 stimulation resulted in increased protein abundance of 58 proteins (3% of proteome), whereas PMA induced changed protein abundance of 207 (10 % of proteome) and LPS of 46 proteins (2% of proteome). Enrichment analyses clearly showed fundamental differences between stimuli, with primary association of IL8 stimulation to processes in immune response, receptor signaling and signal transduction. Top enrichment for PMA on the other hand pointed to vesicle mediated transport and exocytosis. Stimulation with LPS did not result in any significant enrichment. Although we detected 43% overlap of enrichment categories for IL8 and PMA stimulation, indicating that activation of neutrophils with different stimuli partly induces some similar biological processes and pathways, hierarchical clustering showed clear differences in distribution and biological relevance of clusters between the chosen stimuli. Our studies provide novel information on the granulocyte proteome and offer insights into early, differentiated granulocyte reaction to stimuli, which contribute to a better understanding of molecular mechanisms involved in activation and recruitment of neutrophils, through inflammatory stimuli.

Neutrophil Subsets in Periodontal Health and Disease: A Mini Review

Neutrophils are amongst the most abundant immune cells within the periodontal tissues and oral cavity. As innate immune cells, they are first line defenders at the tooth-mucosa interface, and can perform an array of different functions. With regard to these, it has been observed over many years that neutrophils are highly heterogeneous in their behavior. Therefore, it has been speculated that neutrophils, similarly to other leukocytes, exist in distinct subsets. Several studies have investigated different markers of neutrophils in oral health and disease in recent years in order to define potential cell subsets and their specific tasks. This research was inspired by recent advancements in other fields of medicine in this field. The aim of this review is to give an overview of the current evidence regarding the existence and presence of neutrophil subsets and their possible functions, specifically in the context of periodontitis, gingivitis, and periodontal health.

Autophagy in neutrophils

Autophagy is a highly conserved intracellular degradation and energy-recycling mechanism that contributes to the maintenance of cellular homeostasis. Extensive researches over the past decades have defined the role of autophagy innate immune cells. In this review, we describe the current state of knowledge regarding the role of autophagy in neutrophil biology and a picture of molecular mechanism underlying autophagy in neutrophils. Neutrophils are professional phagocytes that comprise the first line of defense against pathogen. Autophagy machineries are highly conserved in neutrophils. Autophagy is not only involved in generalized function of neutrophils such as differentiation in bone marrow but also plays crucial role effector functions of neutrophils such as granule formation, degranulation, neutrophil extracellular traps release, cytokine production, bactericidal activity and controlling inflammation. This review outlines the current understanding of autophagy in neutrophils and provides insight towards identification of novel therapeutics targeting autophagy in neutrophils.

The Beneficial Effects of Antioxidants in Health And Diseases

Reactive oxygen and nitrogen species can be generated endogenously (by mitochondria, peroxisomes, and phagocytic cells) and exogenously (by pollutions, UV exposure, xenobiotic compounds, and cigarette smoke). The negative effects of free radicals are neutralized by antioxidant molecules synthesized in our body, like glutathione, uric acid, or ubiquinone, and those obtained from the diet, such as vitamins C, E, and A, and flavonoids. Different microelements like selenium and zinc have no antioxidant action themselves but are required for the activity of many antioxidant enzymes. Furthermore, circulating blood proteins are suggested to account for more than 50% of the combined antioxidant effects of urate, ascorbate, and vitamin E. Antioxidants together constitute a mutually supportive defense against reactive oxygen and nitrogen species to maintain the oxidant/antioxidant balance. This article outlines the oxidative and anti-oxidative molecules involved in the pathogenesis of chronic obstructive lung disease. The role of albumin and alpha-1 antitrypsin in antioxidant defense is also discussed.

Calcium signaling and regulation of neutrophil functions: Still a long way to go

Neutrophils are the most abundant leukocytes in blood and disruption in their functions often results in an increased risk of serious infections and inflammatory autoimmune diseases. Following recent discoveries in their influence over disease progression, a resurgence of interest for neutrophil biology has taken place. The multitude of signaling pathways activated by the engagement of numerous types of receptors, with which neutrophils are endowed, reflects the functional complexity of these cells. It is therefore not surprising that there remains a huge lack in the understanding of molecular mechanisms underlining neutrophil functions. Moreover, studies on neutrophils are undoubtedly limited by the difficulty to efficiently edit the cell's genome. Over the past 30 years, compelling evidence has clearly highlighted that Ca²⁺ -signaling is governing the key processes associated with neutrophil functions. The confirmation of the role of an elevation of intracellular Ca²⁺ concentration has come from studies on NADPH oxidase activation and phagocytosis. In this review, we give an overview and update of our current knowledge on the role of Ca²⁺ mobilization in the regulation of pro-inflammatory functions of neutrophils. In particular, we stress the importance of Ca²⁺ in the formation of NETs and cytokine secretion in the light of newest findings. This will allow us to embrace how much further we have to go to understand the complex dynamics of Ca²⁺ -dependent mechanisms in order to gain more insights into the role of neutrophils in the pathogenesis of inflammatory diseases. The potential for therapeutics to regulate the neutrophil functions, such as Ca²⁺ influx inhibitors to prevent autoimmune and chronic inflammatory diseases, has been discussed in the last part of the review.

Platelet Serotonin Aggravates Myocardial Ischemia/Reperfusion Injury via Neutrophil Degranulation

BACKGROUND

Platelets store large amounts of serotonin that they release during thrombus formation or acute inflammation. This facilitates hemostasis and modulates the inflammatory response.

METHODS

Infarct size, heart function, and inflammatory cell composition were analyzed in mouse models of myocardial reperfusion injury with genetic and pharmacological depletion of platelet serotonin. These studies were complemented by in vitro serotonin stimulation assays of platelets and leukocytes in mice and men, and by measuring plasma serotonin levels and leukocyte activation in patients with acute coronary syndrome.

RESULTS

Platelet-derived serotonin induced neutrophil degranulation with release of myeloperoxidase and hydrogen peroxide (H₂O₂) and increased expression of membrane-bound leukocyte adhesion molecule CD11b, leading to enhanced inflammation in the infarct area and reduced myocardial salvage. In patients hospitalized with acute coronary syndrome, plasmatic serotonin levels correlated with CD11b expression on neutrophils and myeloperoxidase plasma levels. Long-term serotonin reuptake inhibition-reported to protect patients with depression from cardiovascular events-resulted in the depletion of platelet serotonin stores in mice. These mice displayed a reduction in neutrophil degranulation and preserved cardiac function. In line, patients with depression using serotonin reuptake inhibition, presented with suppressed levels of CD11b surface expression on neutrophils and lower myeloperoxidase levels in blood.

CONCLUSIONS

Taken together, we identify serotonin as a potent therapeutic target in neutrophil-dependent thromboinflammation during myocardial reperfusion injury.

The Regulatory Effects of Interleukin-4 Receptor Signaling on Neutrophils in Type 2 Immune Responses

Interleukin-4 (IL-4) receptor (IL-4R) signaling plays a pivotal role in type 2 immune responses. Type 2 immunity ensures several host-protective processes such as defense against helminth parasites and wound repair, however, type 2 immune responses also drive the pathogenesis of allergic diseases. Neutrophil granulocytes (neutrophils) have not traditionally been considered a part of type 2 immunity. While neutrophils might be beneficial in initiating a type 2 immune response, their involvement and activation is rather unwanted at later stages. This is evidenced by examples of type 2 immune responses where increased neutrophil responses are able to enhance immunity, however, at the cost of increased tissue damage. Recent studies have linked the type 2 cytokines IL-4 and IL-13 and their signaling via type I and type II IL-4Rs on neutrophils to inhibition of several neutrophil effector functions. This mechanism directly curtails neutrophil chemotaxis toward potent intermediary chemoattractants, inhibits the formation of neutrophil extracellular traps, and antagonizes the effects of granulocyte colony-stimulating factor on neutrophils. These effects are observed in both mouse and human neutrophils. Thus, we propose for type 2 immune responses that neutrophils are, as in other immune responses, the first non-resident cells to arrive at a site of inflammation or infection, thereby guiding and attracting other innate and adaptive immune cells; however, as soon as the type 2 cytokines IL-4 and IL-13 predominate, neutrophil recruitment, chemotaxis, and effector functions are rapidly shut off by IL-4/IL-13-mediated IL-4R signaling in neutrophils to prevent them from damaging healthy tissues. Insight into this neutrophil checkpoint pathway will help understand regulation of neutrophilic type 2 inflammation and guide the design of targeted therapeutic approaches for modulating neutrophils during inflammation and neutropenia.

Characterization of Phenotypes and Functional Activities of Leukocytes From Rheumatoid Arthritis Patients by Mass Cytometry

Background: Rheumatoid arthritis (RA) is the most common autoimmune rheumatic disease and leads to persistent chronic inflammation. The pathophysiology of the disease is complex, involving both adaptive and innate immunity. Among innate immune cells, neutrophils have been rarely studied due to their sensitivity to freezing and they are not being collected after Ficoll purification. Methods: We used mass cytometry to perform a multidimensional phenotypic characterization of immune cells from RA-treated patients, which included the simultaneous study of 33 intra- or extra-cellular markers expressed by leukocytes. We were able to focus our study on innate immune cells, especially neutrophils, due to a specific fixation method before freezing. In addition, blood samples were stimulated or not with various TLR agonists to evaluate whether RA-dependent chronic inflammation can lead to immune-cell exhaustion. Results: We show that RA induces the presence of CD11blow neutrophils (33.7 and 9.2% of neutrophils in RA and controls, respectively) associated with the duration of disease. This subpopulation additionally exhibited heterogeneous expression of CD16. We also characterized a CD11ahigh Granzyme Bhigh T-cell subpopulation possibly associated with disease activity. There was no difference in cytokine expression after the stimulation of immune cells by TLR agonists between RA and controls. Conclusion: Mass cytometry and our fixation method allowed us to identify two potential new blood subpopulations of neutrophils and T-cells, which could be involved in RA pathology. The phenotypes of these two potential new subpopulations need to be confirmed using other experimental approaches, and the exact role of these subpopulations is yet to be studied.

Effect of the metanolic extract from the leaves of Garcinia humilis Vahl (Clusiaceae) on acute inflammation

Garcinia humilis is popularly used to treat digestive, intestinal and inflammatory illness. We investigated the in vivo and in vitro effects of the methanol extract of G. humilis leaves (MEGh) on inflammatory cells behavior (migration and chemical mediators release) and hypersensitivity. Anti-inflammatory activity was investigated using carrageenan-induced inflammation in the subcutaneous tissue of male Swiss mice treated orally with MEGh (0.1-30 mg/kg). Leucocyte migration, chemical mediators secretion (TNF, IL-1β, IL-6 and CXCL1) and protein exudation were quantified in the exudate. The adhesion molecules expression (CD62L and CD18), chemical mediators and chemotaxis was evaluated using neutrophils or macrophages RAW.264.7 previously treated with the extract (1-100 µg/mL) and activated with LPS. The anti-inflammatory activity of the isolated compounds friedelin, canophyllol, amentoflavone and 3-desmethyl-2-geranyl-4-prenylbellidypholine xanthone (10 μM) was evaluated in macrophages nitric oxide (NO) and TNF release. MEGh, given orally (30 mg/kg), significantly reduced neutrophil migration and decreased TNF, IL-1β and CXCL1 levels, without interfering with protein exudation and IL-6. In vitro, the extract significantly reduced IL-1β and IL-6 levels but did not alter TNF and CXCL1. The MEGh also reduced the expression of CD62L and CD18 and consequently neutrophil chemotaxis. The compounds friedelin, amentoflavone and 3-demethyl-2-geranyl-4-prenylbellidypholine xanthone decreased the secretion of NO and TNF by RAW264.7. The MEGh effects were extended to the pain-like behaviour induced by carrageenan in the mice hindpaw. MEGh presented important anti-inflammatory effects probably due to its activity on neutrophil migration and on important chemical mediator release, scientifically reinforcing its use as medicinal plant.