Role of neutrophils in innate immunity: a systems biology-level approach

Ex vivo observation of Pythium insidiosum-antigen treated neutrophils on three Pythium insidiosum strains isolated from vascular pythiosis patients

The mechanisms of Pythium insidiosum-antigen (PIA) immunotherapy activating a patient's immune system are unknown. We evaluated the interleukin-8 (IL-8) serum levels during P. insidiosum infection and after vaccination with PIA in vascular pythiosis cases. Furthermore, we studied the anti-P. insidiosum activity of neutrophils stimulated with various concentrations of PIA ex vivo in 3 strains of P. insidiosum isolated from vascular pythiosis patients. IL-8 serum levels were evaluated using the ELISA technique. We assessed the effect of PIA-stimulated neutrophils on the viability of zoospores using MTT assay, visualized neutrophil extracellular trap (NET) formation via microscopy, and measured the levels of double-stranded DNA (dsDNA) using PicoGreen dsDNA quantitation assay in 3 strains of P. insidiosum isolated from vascular pythiosis patients. Serum levels of IL-8 gradually lowered from the early to the end phases of vaccination with PIA among the surviving group of vascular pythiosis cases. Neutrophils stimulated with 0.01 µg/ml PIA reduced zoospore viability significantly compared to PIA-unstimulated neutrophils for strain 1 and strain 3 (p < .05). Neutrophils stimulated with 0.01, 0.1, 1, and 10 µg/ml PIA exhibited significantly lower zoospore viability than PIA-unstimulated neutrophils for strain 2 (p < .05). IL-8 can be used as a biomarker for monitoring vascular pythiosis cases treated with the PIA vaccine. Also, anti-P. insidiosum activity of PIA-stimulated neutrophils was probably due to the disruption of cellular activity in zoospores rather than the mechanisms based on the formation of NETs.

Cadmium aggravates liver injury by activating ferroptosis and neutrophil extracellular traps formation in Nile tilapia (Oreochromis niloticus)

Cadmium (Cd) is a pervasive environmental contaminant and a significant risk factor for liver injury. The present study was undertaken to evaluate the involvement of ferroptosis and neutrophil extracellular traps (NETs) in Cd-induced liver injury in Nile tilapia (Oreochromis niloticus), and to explore its underlying mechanism. Cd-induced liver injury was associated with increased total iron, malondialdehyde (MDA), and Acyl-CoA synthetase long-chain family member 4 (ACSL4), together with reduced levels of glutathione, glutathione peroxidase-4a (Gpx4a), and solute carrier family 7 member 11 (SLC7A11), which are all hallmarks of ferroptosis. Moreover, liver hyperemia, neutrophil infiltration, increased inflammatory factors and myeloperoxidase, as well as elevated serum DNA content in Cd-stimulated Nile tilapia suggested that a considerable number of neutrophils were recruited to the liver. Furtherly, in vitro experiments demonstrated that Cd induced the formation of NETs, and the possible mechanism was related to the generation of reactive oxygen species and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, along with the P38 and extracellular regulated protein kinase (ERK) signaling pathways. We concluded that ferroptosis and NETs are the critical mechanisms contributing to Cd-induced liver injury in Nile tilapia. These findings will contribute to Cd toxicological studies in aquatic animals.

Biological functions and biomedical applications of extracellular vesicles derived from blood cells

There is a growing interest in using extracellular vesicles (EVs) for therapeutic applications. EVs are composed of cytoplasmic proteins and nucleic acids and an external lipid bilayer containing transmembrane proteins on their surfaces. EVs can alter the state of the target cells by interacting with the receptor ligand of the target cell or by being internalised by the target cell. Blood cells are the primary source of EVs, and 1 μL of plasma contains approximately 1.5 × 107 EVs. Owing to their easy acquisition and the avoidance of cell amplification in vitro, using blood cells as a source of therapeutic EVs has promising clinical application prospects. This review summarises the characteristics and biological functions of EVs derived from different blood cell types (platelets, erythrocytes, and leukocytes) and analyses the prospects and challenges of using them for clinical therapeutic applications. In summary, blood cell-derived EVs can regulate different cell types such as immune cells (macrophages, T cells, and dendritic cells), stem cells, and somatic cells, and play a role in intercellular communication, immune regulation, and cell proliferation. Overall, blood cell-derived EVs have the potential for use in vascular diseases, inflammatory diseases, degenerative diseases, and injuries. To promote the clinical translation of blood cell-derived EVs, researchers need to perform further studies on EVs in terms of scalable and reproducible isolation technology, quality control, safety, stability and storage, regulatory issues, cost-effectiveness, and long-term efficacy.

Association of systemic inflammatory response index and plaque characteristics with the severity and recurrence of cerebral ischemic events

AIM

We aimed to investigate the relationship between systemic inflammatory response index (SIRI) and intracranial plaque features, as well as the risk factors related to the severity and recurrence of cerebral ischemic events.

METHODS

We enrolled 170 patients with cerebral ischemic events. Baseline demographic characteristics and laboratory indicators were collected from all participants. All patients were assessed by high-resolution magnetic resonance vessel wall imaging for culprit plaque characteristics and intracranial atherosclerotic burden. Outpatient or telephone follow-up were conducted at 1, 3, and 6 months after discharge.

RESULTS

SIRI levels were significantly associated with the enhanced plaque number (r = 0.205, p = 0.007), total plaque stenosis score (r = 0.178, p = 0.020), total plaque enhancement score (r = 0.222, p = 0.004), intraplaque hemorrhage (F = 5.630, p = 0.004), and plaque surface irregularity (F = 3.986, p = 0.021). Higher SIRI levels (OR = 1.892), total plaque enhancement score (OR = 1.392), intraplaque hemorrhage (OR = 3.370) and plaque surface irregularity (OR = 2.846) were independent risk factors for moderate-severe stroke, and these variables were significantly positively correlated with NIHSS (P < 0.05 for all). In addition, higher age (HR = 1.063, P = 0.015), higher SIRI levels (HR = 2.003, P < 0.001), and intraplaque hemorrhage (HR = 4.482, P = 0.008) were independently associated with recurrent stroke.

CONCLUSIONS

Higher SIRI levels may have adverse effects on the vulnerability and burden of intracranial plaques, and links to the severity and recurrence of ischemic events. Therefore, SIRI may provide important supplementary information for evaluating intracranial plaque stability and risk stratification of patients.

Crosstalk between keratinocytes and neutrophils shapes skin immunity against S. aureus infection

Introduction

Staphylococcus aureus (S. aureus) infection of the skin leads to a rapid initial innate immune response with keratinocytes in the epidermis as the initial sensors. Polymorphonuclear neutrophils (PMNs) are the first innate immune cells to infiltrate infection sites where they provide an effective first-line of defense. Previous work of our group showed that in inflamed skin a crosstalk between PMNs and keratinocytes results in enhanced S. aureus skin colonization.

Methods

In this work, we used an in vitro co-culture model to studied the crosstalk between primary human keratinocytes (PHKs) and PMNs in a sterile environment and upon S. aureus infection. We investigated the influence of PHKs on PMN activation by analyzing PMN lifespan, expression of degranulation markers and induction of proinflammatory cytokines. Furthermore, we analyzed the influence of PMNs on the inflammatory response of PHKs. Finally, we investigated the influence of the skin microbiome on PMN-mediated skin inflammation.

Results

We show that co-culture of PMNs with PHKs induces activation and degranulation of PMNs and significantly enhances their lifespan compared to PMN cultivation alone by an IL-8 mediated mechanism and, furthermore, primes PMNs for enhanced activity after S. aureus infection. The prolonged incubation with PMNs also induces inflammatory responses in PHKs which are further exacerbated in the presence of S. aureus and induces further PMN recruitment thus fueling skin inflammation. Interestingly, infection of PHKs with the skin commensal S. epidermidis reduces the inflammatory effects of PMNs in the skin and exhibits an anti-inflammatory effect.

Discussion

Our data indicate that skin infiltrating PMNs and PHKs influence each other in such a way to enhance skin inflammation and that commensal bacteria are able to reduce the inflammatory effect.

Relationship between the lymphocyte to C‑reactive protein ratio and coronary artery disease severity

Coronary atherosclerosis is a chronic systemic inflammatory disease. Laboratory parameters such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune inflammation index (SII) have been used to assess inflammation degree and coronary artery disease (CAD) severity. The lymphocyte-to-C-reactive protein ratio (LCR) is a new SII. However, its relationship with CAD development and severity is unclear. A total of 1,107 patients (479 in control group, 628 in CAD group) underwent coronary angiography. The routine and biochemical indices of the venous blood of patients were assessed before coronary angiography. LCR, SII, NLR and PLR were calculated and statistical analyses were performed. Propensity score matching (PSM) and a logistic regression model were used to analyze the relationship between LCR and CAD. After the PSM, 384 pairs of patients with or without CAD were successfully matched. After the median binary classification of all indicators, uni- and multivariate logistic regression analyses showed that platelet count was an independent risk factor and LCR was an independent protective factor. Using the same method, in the coronary heart disease severity group, 212 pairs were successfully matched and NLR and PLR were independent risk factors, while LCR was an independent protective factor. In conclusion, LCR is an independent protective factor against CAD development and severity.

Suggested role for neutrophil extracellular trap formation in Ewing sarcoma immune microenvironment

Ewing sarcoma (EWS) is a highly aggressive cancer with a survival rate of 70%-80% for patients with localized disease and under 30% for those with metastatic disease. Tumor-infiltrating neutrophils (TIN) can generate extracellular net-like DNA structures known as neutrophil extracellular traps (NETs). However, little is known about the presence and prognostic significance of tumor-infiltrating NETs in EWS. Herein, we investigated 46 patients diagnosed with EWS and treated in the Tel Aviv Medical Center between 2010 and 2021. TINs and NETs were identified in diagnostic biopsies of EWS by immunofluorescence. In addition, NETs were investigated in neutrophils isolated from peripheral blood samples of EWS patients at diagnosis and following neoadjuvant chemotherapy. The relationships between the presence of TINs and NETs, pathological and clinical features, and outcomes were analyzed. Our results demonstrate that TIN and NETs at diagnosis were higher in EWS patients with metastatic disease compared with those with local disease. High NET formation at diagnosis predicted poor response to neoadjuvant chemotherapy, relapse, and death from disease (p < 0.05). NET formation in peripheral blood samples at diagnosis was significantly elevated among patients with EWS compared with pediatric controls and decreased significantly following neoadjuvant chemotherapy. In conclusion, NET formation seems to have a role in the EWS immune microenvironment. Their presence can refine risk stratification, predict chemotherapy resistance and survival, and serve as a therapeutic target in patients with EWS.

Bcl-xL targeting eliminates ageing tumor-promoting neutrophils and inhibits lung tumor growth

Elevated peripheral blood and tumor-infiltrating neutrophils are often associated with a poor patient prognosis. However, therapeutic strategies to target these cells are difficult to implement due to the life-threatening risk of neutropenia. In a genetically engineered mouse model of lung adenocarcinoma, tumor-associated neutrophils (TAN) demonstrate tumor-supportive capacities and have a prolonged lifespan compared to circulating neutrophils. Here, we show that tumor cell-derived GM-CSF triggers the expression of the anti-apoptotic Bcl-xL protein and enhances neutrophil survival through JAK/STAT signaling. Targeting Bcl-xL activity with a specific BH3 mimetic, A-1331852, blocked the induced neutrophil survival without impacting their normal lifespan. Specifically, oral administration with A-1331852 decreased TAN survival and abundance, and reduced tumor growth without causing neutropenia. We also show that G-CSF, a drug used to combat neutropenia in patients receiving chemotherapy, increased the proportion of young TANs and augmented the anti-tumor effect resulting from Bcl-xL blockade. Finally, our human tumor data indicate the same role for Bcl-xL on pro-tumoral neutrophil survival. These results altogether provide preclinical evidence for safe neutrophil targeting based on their aberrant intra-tumor longevity.

Mycobacterium tuberculosis: immune response, biomarkers, and therapeutic intervention

Although tuberculosis (TB) is an infectious disease, the progression of the disease following Mycobacterium tuberculosis (MTB) infection is closely associated with the host's immune response. In this review, a comprehensive analysis of TB prevention, diagnosis, and treatment was conducted from an immunological perspective. First, we delved into the host's immune response mechanisms against MTB infection as well as the immune evasion mechanisms of the bacteria. Addressing the challenges currently faced in TB diagnosis and treatment, we also emphasized the importance of protein, genetic, and immunological biomarkers, aiming to provide new insights for early and personalized diagnosis and treatment of TB. Building upon this foundation, we further discussed intervention strategies involving chemical and immunological treatments for the increasingly critical issue of drug-resistant TB and other forms of TB. Finally, we summarized TB prevention, diagnosis, and treatment challenges and put forward future perspectives. Overall, these findings provide valuable insights into the immunological aspects of TB and offer new directions toward achieving the WHO's goal of eradicating TB by 2035.

Streptococcus pyogenes emm98.1 variants activate inflammatory caspases in human neutrophils

ABBREVIATIONS

CovRS, control of virulence regulatory system; GAS, Group A Streptococcus; PMN, polymorphonuclear leukocyte.

Influence of androgens on the innate immune system

BACKGROUND

Sexual dimorphism is observed in the occurrence, course, and severity of human disease. The difference in immune response between males and females can in part be attributed to sexual genotype. However, immunological differences can also be explained by endocrine-immune interactions. Specifically, androgens possess the ability of directly modulating the development and function of immune cells. Although androgens generally contribute to immunosuppressive effects, this is not necessarily always the case.

AIM

The aim of the review is to uncover the role of androgens in shaping the innate immune response.

MATERIAL & METHODS

Authors included papers in this review which discussed the impact of androgens on specific innate immune cells.

RESULTS

Androgens modulate the innate immune response through various mechanisms. However, there is conflicting evidence in the literature regarding the interplay betwen androgens and the innate immune system.

DISCUSSION

Conflicting evidence presented in this review could in part be explained by the limitations present in interpreting results.

CONCLUSION

This review is of great importance for our understanding of occurence and mechanism of human inflammatory disease.

The structures of two acidic polysaccharides from Gardenia jasminoides and their potential immunomodulatory activities

This study identified two homogeneous acidic polysaccharides from Gardeniae fructus, GJP50-3 and GJP50-4, which exhibited potential immunomodulatory activities in macrophage activation assays, via liquid-chip technology, and in a zebrafish model. Monosaccharide composition analysis and gel permeation chromatography revealed that GJP50-3 and GJP50-4 were composed of Rha, GalA, Glc, Gal, and Ara in specific ratios and had molecular weights of 91.5 kDa and 140.3 kDa, respectively. Based on FT-IR, GC-MS, and NMR analyses, these polysaccharides were identified as typical pectin polysaccharides with methylation degrees of 24.7 % and 21.4 %, respectively. The primary structures of GJP50-3 and GJP50-4 included linear HG domains and branched RG-I domains with arabinans and AG side chains. In vitro, GJP50-3 and GJP50-4 could stimulate NO release and increase the secretion of TNF-α in a RAW 264.7 macrophage model. Luminex liquid suspension chip detection revealed that GJP50-3 significantly promoted the secretion of multiple interleukins [IL-6, IL-9, IL-10, IL-12 (p40), IL-12 (p70), IL-13], TNF-α, and chemokines (G-CSF, GM-CSF, MCP-1 and RANTES). In vivo, these polysaccharides could also increase NO release and neutrophil count in a zebrafish model. These findings suggested that GJP50-3 and GJP50-4 might have the potential to be used as immunomodulators in the food and pharmaceutical industries.

Neutrophils extracellular traps formation may serve as a biomarker for disease activity in oligoarticular juvenile idiopathic arthritis: a pilot study

BACKGROUND

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in children, causing significant morbidity. Despite the dramatic improvement in treatment, many patients do not achieve complete remission, and biomarkers for subclinical disease, flares, and response to treatment are lacking. Neutrophils and neutrophil extracellular traps (NETs) play key roles in the pathogenesis of autoimmune and inflammatory conditions. In this study, we characterized neutrophil enzyme activity and NETs formation in oligoarticular and polyarticular JIA and explored their association with disease activity.

METHODS

Neutrophils from 6 healthy controls and 7 patients with oligoarticular and polyarticular JIA were freshly isolated at time of diagnosis and after glucocorticoid intra-articular injection. Enzymatic activity of neutrophil granular enzymes was monitored by colorimetry and PMA-activated NETs formation was assessed using fluorescent microscopy.

RESULTS

In this pilot and feasibility study, we revealed that NETs were significantly increased in oligoarticular JIA patients at time of diagnosis compared to healthy controls. Anti-inflammatory treatment using intra-articular steroid injection normalized NETs formation in these patients. Correlation between NETs formation and clinical Juvenile Activity Disease Activity Score-10 (cJADAS-10) was linear and significant (P = 0.007) in oligo but not in poly JIA patients.

CONCLUSIONS

This is the first study exploring the link of NETs formation with oligo and poly JIA activity. We demonstrated a statistically significant linear correlation between cJADAS-10 and NETs formation in oligo but not in poly JIA patients. Hence, we suggest that NETs may reflect clinical disease activity in JIA, and may serve as a putative biomarker. Further work is needed to validate these initial results and determine the dynamics of NETs formation in JIA.

Use of Systemic Steroids, Hormone Replacement Therapy, or Oral Contraceptives Is Associated with Decreased Implant Survival in Women

BACKGROUND

Systemic steroids, such as prednisone, hormonal replacement therapies, or oral contraceptives, are commonly prescribed to women who might also be receiving dental implant therapy. However, the effect of these medications on dental implant survival is unknown.

METHODS

The medical and dental records of individuals with dental implants (N = 1480 implants) who visited a postgraduate periodontics clinic between 2000 and 2017 were initially considered. Those younger than 21 years old, pregnant, or male were excluded according to the study's exclusion criteria. The presence of systemic diseases and conditions was assessed. Implant failure rates among female patients using systemic steroids, hormone replacement therapy, or oral contraceptives were compared with failure rates among patients not taking those medications.

RESULTS

The implant failure rate for the 65 implants in patients taking steroid medications was 7.69%; the failure rate for the 712 implants in patients not taking steroids was 1.54% (p < 0.001). After adjusting for smoking and the presence of diabetes, that relationship persisted, with an 8.47% implant failure rate for the 59 implants in patients taking steroids (vs. 1.54% failure for the 585 implants in patients not taking steroids; p < 0.001). Regression analyses demonstrated that the odds of implant failure versus success were 5.31 times greater in patients taking systemic steroids, hormone replacement therapy, or oral contraceptives (p < 0.05). No statistically significant differences in patient plaque control were found between the experimental and control groups.

CONCLUSIONS

Among women, the use of systemic steroids is associated with a five-fold increase in the rate of dental implant failure, regardless of the presence of smoking or diabetes.

The Involvement of Neutrophil in the Immune Dysfunction Associated with BVDV Infection

Bovine viral diarrhea virus (BVDV) induces immune dysfunction that often results in a secondary bacterial infection in the infected animals. The underlying mechanism of BVDV-induced immune dysfunction is not well understood. The role of BVDV-infected macrophage-secreted factors was investigated. BVDV-infected monocyte-derived macrophage (MDM) supernatants down-regulated the expression of neutrophil L-selectin and CD18. Regardless of the biotype, phagocytic activity and oxidative burst were downregulated by BVDV-infected MDM supernatants. However, only supernatants from cytopathic (cp) BVDV down-regulated nitric oxide production and neutrophil extracellular traps (NET) induction. Our data suggested that BVDV-induced macrophage-secreted factors caused immune dysfunction in neutrophils. Unlike lymphocyte depletion, the negative impact on neutrophils seems to be specific to cp BVDV biotype. Interestingly the majority of modified live BVDV vaccines are based on cp strain of BVDV.

Metataxonomic analysis and host proteome response in dairy cows with high and low somatic cell count: a quarter level investigation

Host response to invasive microbes in the bovine udder has an important role on the animal health and is essential to the dairy industry to ensure production of high-quality milk and reduce the mastitis incidence. To better understand the biology behind these host-microbiome interactions, we investigated the somatic cell proteomes at quarter level for four cows (collected before and after milking) using a shotgun proteomics approach. Simultaneously, we identified the quarter microbiota by amplicon sequencing to detect presence of mastitis pathogens or other commensal taxa. In total, 32 quarter milk samples were analyzed divided in two groups depending on the somatic cell count (SCC). The high SCC group (>100,000 cell/mL) included 10 samples and significant different proteome profiles were detected. Differential abundance analysis uncovers a specific expression pattern in high SCC samples revealing pathways involved in immune responses such as inflammation, activation of the complement system, migration of immune cells, and tight junctions. Interestingly, different proteome profiles were also identified in quarter samples containing one of the two mastitis pathogens, Staphylococcus aureus and Streptococcus uberis, indicating a different response of the host depending on the pathogen. Weighted correlation network analysis identified three modules of co-expressed proteins which were correlated with the SCC in the quarters. These modules contained proteins assigned to different aspects of the immune response, but also amino sugar and nucleotide sugar metabolism, and biosynthesis of amino acids. The results of this study provide deeper insights on how the proteome expression changes at quarter level in naturally infected cows and pinpoint potential interactions and important biological functions during host-microbe interaction.

Association Between Neutrophil Density and Survival in Trauma Patients Admitted to the Intensive Care Unit; a Retrospective Cohort Study

Introduction

Altered immune responses, in particular neutrophil changes, are perceived to play a key role in immune responses to trauma. This study aimed to evaluate the association of neutrophil changes with patients' survival in severe multiple trauma cases.

Methods

The current retrospective cohort study was conducted using data from patients admitted in the intensive care unit (ICU) of a trauma center in Shiraz, Iran, between 2016 and 2021. Patients were divided into three groups (i.e., normal, neutropenia, and neutrophilia) based on neutrophil count at the time of ICU admission, and the association of neutrophil count with in-hospital mortality was analyzed.

Results

2176 patients with the mean age of 37.90 ± 18.57 years were evaluated (84.04% male). The median trauma severity based on injury severity score (ISS) in this series was 9 (4 -17). Patients were divided in to three groups of neutrophilia (n = 1805), normal (n = 357), and neutropenia (n = 14). There were not any significant differences between groups regarding age distribution (p = 0.634), gender (p = 0.544), and trauma severity (p = 0.197). The median survival times for the normal, neutropenia, and neutrophilia groups were 49 (IQR: 33 -47) days, 51 (IQR: 8- 51) days, and 38 (IQR: 26 - 52) days, respectively (p = 0.346). The log-rank test showed a statistically significant difference between the three groups adjustment for ISS (p ≤ 0.001). For each unit increase in ISS, the hazard ratio increased by 2%. In ISS 9-17, the hazard ratio increased by 11% compared to ISS<4. Also, in ISS>17, the hazard ratio increased by 76% compared to ISS<4 in ICU-hospitalized patients.

Conclusions

In general, the findings of the present study showed that the survival rate of patients in the normal group after ISS adjustment was higher than the other two groups. Also, the Cox model showed that the mortality risk ratio in the neutropenia group was 15 times higher than the normal group.

Androgen and prolactin manipulation do not induce changes in immunocompetence measures in a fish with male parental care

Prolactin and 11-ketotestosterone (11-KT) are important reproductive hormones in fishes, which may also influence immunocompetence. The immunocompetence handicap hypothesis states that higher androgen concentrations that support secondary sex traits are traded off against a decrease in immune system function. To test the relationships between these hormones and immunocompetence, we experimentally manipulated 11-ketotestosterone and prolactin in the freshwater fish, bluegill (Lepomis macrochirus) during parental care using implants that contained either 11-KT, prolactin, or an inert control. We vaccinated individuals to stimulate the acquired immune response, then measured immunocompetence as the number of granulocytes, lymphocytes and monocytes, and the expression of interleukin 8 in each sample. We did not observe any significant differences in the immune measures among the hormone treatments. Our results indicate that in bluegill, there is no trade-off between androgens or prolactin and immunocompetence.

Immunomodulatory Properties of Vitamin D in the Intestinal and Respiratory Systems

Vitamin D plays a crucial role in modulating the innate immune response by interacting with its intracellular receptor, VDR. In this review, we address vitamin D/VDR signaling and how it contributes to the regulation of intestinal and respiratory microbiota. We additionally review some components of the innate immune system, such as the barrier function of the pulmonary and intestinal epithelial membranes and secretion of mucus, with their respective modulation by vitamin D. We also explore the mechanisms by which this vitamin D/VDR signaling mounts an antimicrobial response through the transduction of microbial signals and the production of antimicrobial peptides that constitute one of the body’s first lines of defense against pathogens. Additionally, we highlight the role of vitamin D in clinical diseases, namely inflammatory bowel disease and acute respiratory distress syndrome, where excessive inflammatory responses and dysbiosis are hallmarks. Increasing evidence suggests that vitamin D supplementation may have potentially beneficial effects on those diseases.

Curcumin and chemokines: mechanism of action and therapeutic potential in inflammatory diseases

Chemokines belong to the family of cytokines with chemoattractant properties that regulate chemotaxis and leukocyte migration, as well as the induction of angiogenesis and maintenance of hemostasis. Curcumin, the major component of the Curcuma longa rhizome, has various pharmacological actions, including anti-inflammatory, immune-regulatory, anti-oxidative, and lipid-modifying properties. Chemokines and chemokine receptors are influenced/modulated by curcumin. Thus, the current review focuses on the molecular mechanisms associated with curcumin's effects on chemoattractant cytokines, as well as putting into context the many studies that have reported curcumin-mediated regulatory effects on inflammatory conditions in the organs/systems of the body (e.g., the central nervous system, liver, and cardiovascular system). Curcumin's effects on viral and bacterial infections, cancer, and adverse pregnancy outcomes are also reviewed.

Neutrophil extracellular trap: A key player in the pathogenesis of autoimmune diseases

Numerous studies suggest that neutrophils might have a crucial role in the pathogenesis of systemic autoimmune diseases through neutrophil extracellular trap (NET) formation, production of pro-inflammatory cytokines, and organ destruction. NET components that are released into extracellular spaces can be considered autoantigens, which contribute to causing a break in self-tolerance. Subsequently, this leads to the development of autoimmune responses in predisposed individuals. Additionally, an imbalance between NET formation and NET degradation may prolong immune system contact with these modified autoantigens and enhance NET-induced tissue damage. In this review, we discuss the generation and clearance of the NET, as well as the role of NETosis in the pathogenesis of autoimmune disorders, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), multiple sclerosis (MS), psoriasis, antiphospholipid syndrome (APS), and Type-1 diabetes mellitus (T1DM).

Cyhalofop-butyl exposure induces the severe hepatotoxicity and immunotoxicity in zebrafish embryos

Cyhalofop-butyl (CyB) is a highly effective herbicide and is widely used for weed control in paddy fields. Because CyB is easily residual in the aquatic environment, its potential harm to aquatic organisms has attracted much attention and has not been fully understood. In this study, we systematically explored the hepatotoxic and immunotoxic effects of CyB exposure in zebrafish embryos. Firstly, CyB induced a decrease in the survival rate of zebrafish and led to a series of developmental abnormalities. Meanwhile, CyB can significantly reduce the size of zebrafish liver tissue and the number of hepatocytes in a dose-dependent manner. Secondly, the number of macrophages and neutrophils significantly decreased but the antioxidant enzyme activities such as CAT and MDA were greatly elevated upon CyB exposure. Thirdly, RNA-Seq analysis identified 1, 402 differentially expressed genes (DEGs) including 621 up-regulated and 781 down-regulated in zebrafish embryos after CyB exposure. KEGG and GO functional analysis revealed that the metabolic pathways of drug metabolism-cytochrome P450, biosynthesis of antibiotics, and metabolism of xenobiotics, along with oxidation-reduction process, high-density lipoprotein particle and cholesterol transport activity were significantly enriched after CyB exposure. Besides, hierarchical clustering analysis suggested that the genes involved in lipid metabolism, oxidative stress and innate immunity were largely activated in CyB-exposed zebrafish. Moreover, CyB induced zebrafish liver injury and increased hepatocyte apoptosis, which increased the protein expression levels of Bax, TLR4, NF-kB p65 and STAT3 in zebrafish. Finally, specific inhibition of TLR signaling pathway by TLR4 knock-down could significantly reduce the expression of inflammatory cytokines induced by CyB exposure. Taken together, these informations demonstrated that CyB could induce the hepatotoxicity and immunotoxicity in zebrafish embryos, and the expression levels of many genes involved in lipid metabolism and immune inflammation were obtained by RNA-Seq analysis. This study provides valuable information for future elucidating the aquatic toxicity of herbicide in aquatic ecosystems.

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.

Immunosuppression by opioids: Mechanisms of action on innate and adaptive immunity

Opioids are excellent analgesics for the clinical treatment of various types of acute and chronic pain, particularly cancer-related pain. Nevertheless, it is well known that opioids have some nasty side effects, including immunosuppression, which is commonly overlooked. As a result, the incidence of opportunistic bacterial and viral infections increases in patients with long-term opioid use. Nowadays, there are no effective medications to alleviate opioid-induced immunosuppression. Understanding the underlying molecular mechanism of opioids in immunosuppression can enable researchers to devise effective therapeutic interventions. This review comprehensively summarized the exogenous opioids-induced immunosuppressive effects and their underlying mechanisms, the regulatory roles of endogenous opioids on the immune system, the potential link between opioid immunosuppressive effect and the function of the central nervous system (CNS), and the future perspectives in this field.

The deleterious effect of xylene-induced ear edema in rats: Protective role of dexketoprofen trometamol transdermal invasomes via inhibiting the oxidative stress/NF-κB/COX-2 pathway

Pain and inflammation could have a negative impact on a patient's quality of life and performance, causing them to sleep less. Dexketoprofen trometamol (DKT) is a water-soluble, nonselective NSAIDs. Because DKT is quickly eliminated in the urine after oral delivery, its efficacy is limited and must be taken repeatedly throughout the day. The main ambition of this work is to develop and characterize the potential of invasomes to enhance the transdermal transport of DKT to achieve efficient anti-inflammatory and pain management. The optimum formulation (C1) showed the least %RE (53.29 ± 2.68 %), the highest %EE (86.51 ± 1.05 %), and spherical nanosized vesicles (211.9 ± 0.57 nm) with (PDI) of 0.353 ± 0.01 and (ZP) of -19.15 ± 2.45 mV. DKT flux and deposition in stratum corneum, epidermal, and dermal skin layers were significantly augmented by 2.6 and 3.51 folds, respectively, from the optimum invasomal gel formulation (C1-G) compared to DKT conventional gel (DKT-G). The anti-inflammatory activity of C1-G was evaluated using a model of xylene-induced ear edema in rats. Xylene exposure upregulated the ear expression of COX-2 level and MPO activity. Xylene also significantly increased the ear NF-κB p65, TNF-α, IL-Iβ, and MDA levels. Furthermore, xylene induced oxidative stress, as evidenced by a significant decrease in ear GSH and serum TAC levels. These impacts were drastically improved by applying C1-G compared to rats that received DKT-G and plain invasomal gel formulation (plain C1-G). The histopathological findings imparted substantiation to the biochemical and molecular investigations. Thereby, C1-G could be a promising transdermal drug delivery system to improve the anti-inflammatory and pain management of DKT.

The Neutrophil-to-Lymphocyte Ratio and Preoperative Pulmonary Function Test Results as Predictors of In-Hospital Postoperative Complications after Hip Fracture Surgery in Older Adults

Purpose: This study retrospectively evaluated the usefulness of the neutrophil-to-lymphocyte ratio (NLR), prognostic nutritional index (PNI), and pulmonary function test (PFT) results as objective predictors of in-hospital postoperative complications after hip fracture surgery in older adults. Methods: The patients aged >65 years who underwent hip fracture surgery under general anaesthesia were enrolled. In-hospital postoperative complications with preoperative NLR, PNI and PFT results were evaluated. The NLR was calculated as the preoperative neutrophil count/lymphocyte count in peripheral blood. The PNI was calculated as the serum albumin (g/dL) × 10 + total lymphocyte count × 0.005 (/mm3). Results: One hundred ninety nine patients were analysed. The most common postoperative complications were respiratory complications. Compared with patients who did not have postoperative complications, patients with postoperative complications had a significantly higher NLR (8.01 ± 4.70 vs. 5.12 ± 4.34, p < 0.001), whereas they had a significantly lower PNI (38.33 ± 6.80 vs. 42.67 ± 6.47, p < 0.001), preoperative functional vital capacity (FVC; 2.04 ± 0.76 vs. 2.45 ± 0.71 L, p < 0.001), and forced expiratory volume at 1 s (FEV1; 1.43 ± 0.53 vs. 1.78 ± 0.58 L, p < 0.001). Multiple logistic regression analysis identified NLR (odds ratio [OR], 1.142; 95% confidence interval [CI], 1.060−1.230; p < 0.001) and FEV1 (OR, 0.340; 95% CI, 0.191−0.603; p < 0.001) as risk factors for postoperative complications after hip fracture surgery. Conclusion: Preoperative NLR and FEV1 are objective predictors of in-hospital postoperative complications after hip fracture surgery in older patients.

Role of neutrophil extracellular traps in inflammatory evolution in severe acute pancreatitis

ABSTRACT

Severe acute pancreatitis (SAP) is a life-threatening acute abdominal disease with two peaks of death: the first in the early stage, characterized by systemic inflammatory response-associated organ failure; and the second in the late stage, characterized by infectious complications. Neutrophils are the main immune cells participating in the whole process of SAP. In addition to the traditional recognition of neutrophils as the origination of chemokine and cytokine cascades or phagocytosis and degranulation of pathogens, neutrophil extracellular traps (NETs) also play an important roles in inflammatory reactions. We reviewed the role of NETs in the occurrence and development of SAP and its fatal complications, including multiple organs injury, infected pancreatic necrosis, and thrombosis. This review provides novel insights into the involvement of NETs throughout the entire process of SAP, showing that targeting NETs might be a promising strategy in SAP treatment. However, precision therapeutic options targeting NETs in different situations require further investigation.

Surface Engineering of Protein Nanoparticles Modulates Transport, Adsorption, and Uptake in Mucus

Protein nanoparticles have been demonstrated as effective carriers for protein antigens and therapeutics due to properties endowed by their protein composition. They exhibit high protein to carrier yields, biocompatibility, and heterogeneous surface properties. While protein nanoparticles have been delivered via multiple routes, including intranasal, their interactions with mucosal barriers have not been well studied or modified. Biological barriers associated with intranasal delivery consist of viscoelastic mucus that hinders material transport through surface interactions and the underlying epithelium. Herein, we altered protein nanoparticle surface properties and characterized interactions with nasal mucus and the subsequent effects on diffusion, cellular uptake, and immune cell maturation. Ovalbumin protein nanoparticles were used, serving as a model vaccine nanoparticle. Unmodified ovalbumin protein nanoparticles were compared to cationic ovalbumin particles functionalized with amine groups, neutral particles functionalized with polyethylene glycol, and zwitterionic particles coated layer-by-layer (LBL) with chitosan and oligonucleotides. Transport analysis indicated rapid diffusion of polyethylene glycol and LBL-modified ovalbumin nanoparticles in porcine nasal mucus, while cationic particles were mucoadhesive. Cellular uptake in the presence of mucus by epithelial and dendritic cells was highest for particles containing positive charges, both LBL and amine-functionalized. These particles also exhibited the most diverse adsorbed protein corona from nasal fluids. The corona impacted both dendritic cell uptake and maturation, with polyethylene glycol and LBL modifications improving CD86 expression. Altogether, surface modifications on protein-based nanocarriers are shown to facilitate distinctive physical and cellular behavior associated with mucosal delivery.

The Role of Reactive Species on Innate Immunity

This review examines the role of reactive species RS (of oxygen ROS, nitrogen RNS and halogen RHS) on innate immunity. The importance of these species in innate immunity was first recognized in phagocytes that underwent a “respiratory burst” after activation. The anion superoxide ^•O₂⁻ and hydrogen peroxide H₂O₂ are detrimental to the microbial population. NADPH oxidase NOx, as an ^•O₂⁻ producer is essential for microbial destruction, and patients lacking this functional oxidase are more susceptible to microbial infections. Reactive nitrogen species RNS (the most important are nitric oxide radical -^•NO, peroxynitrite ONOO^— and its derivatives), are also harmful to microorganisms, including bacteria, viruses, and parasites. Hypochlorous acid HOCl and hypothiocyanous acid HOSCN synthesized through the enzyme myeloperoxidase MPO, which catalyzes the reaction between H₂O₂ and Cl⁻ or SCN⁻, are important inorganic bactericidal molecules, effective against a wide range of microbes. This review also discusses the role of antimicrobial peptides AMPs and their induction of ROS. In summary, reactive species RS are the heart of the innate immune system, and they are necessary for microbial lysis in infections that can affect mammals throughout their lives.

The Phylogeny, Ontogeny, and Organ-specific Differentiation of Macrophages in the Developing Intestine

Macrophages are large highly motile phagocytic leukocytes that appear early during embryonic development and have been conserved during evolution. The developmental roles of macrophages were first described nearly a century ago, at about the time these cells were being identified as central effectors in phagocytosis and elimination of microbes. Since then, we have made considerable progress in understanding the development of various subsets of macrophages and the diverse roles these cells play in both physiology and disease. This article reviews the phylogeny and the ontogeny of macrophages with a particular focus on the gastrointestinal tract, and the role of these mucosal macrophages in immune surveillance, innate immunity, homeostasis, tissue remodeling, angiogenesis, and repair of damaged tissues. We also discuss the importance of these macrophages in the inflammatory changes in neonatal necrotizing enterocolitis (NEC). This article presents a combination of our own peer-reviewed clinical and preclinical studies, with an extensive review of the literature using the databases PubMed, EMBASE, and Scopus.

Palmitic acid hinders extracellular traps of neutrophil from postpartum dairy cow in vitro

Peripartum dairy cows experience negative energy balance, characterized by high concentrations of blood free fatty acids (FFA) and immune dysfunction. Palmitic acid (PA), the most abundant saturated fatty acid in cow blood, is not only an energy precursor, but causes cellular dysfunction when in excess. Neutrophil extracellular traps (NET) are one of the arsenals of weapons neutrophils use to fight invading pathogens. However, given the marked increase in circulating PA during the peripartum period, it remains to be determined what effect (if any) PA has on NET release. Thus, the objective of this study was to evaluate the effect of PA on NET release and the underlying mechanism in vitro. Phorbol-12-myristate-13-acetate (PMA; 100 ng/mL, 3 h) was used to induce the release of NET in vitro. We isolated neutrophils from the peripheral blood of 5 healthy postpartum dairy cows with similar parity (median = 3, range = 2-4), milk yield (median = 27.84 kg/d per cow, range = 25.79-31.43 kg/d per cow), days in milk (median = 7 d, range = 4-10 d), and serum FFA <0.25 mM, β-hydroxybutyric acid <0.6 mM, and glucose >3.5 mM. Inhibition of double-stranded DNA (dsDNA) level, a marker of NET release, in response to PA was used to determine an optimal incubation time and concentration for in vitro experiments. Cells were maintained in RPMI-1640 basic medium without phenol red, treated with 600 μM PA for different times (4, 5, 6, and 7 h) in the presence or absence of PMA. There was a decrease for dsDNA level in the supernatant due to increased duration of PA treatment, with a peak response at 6 h. Thus, 6 h was selected as the challenge time. Then, cells were treated with different concentrations of PA (100, 200, 400, and 600 μM) for 6 h in the presence or absence of PMA. There was a decrease for dsDNA level in the supernatant due to increased dose of PA, with a peak response at 400 μM. Finally, 400 μM PA for 6 h was selected as the treatment for subsequent experiments. Protein abundance of citrullinated histone in the presence or absence of PMA was markedly lower in response to incubation with PA. Morphological observations by laser confocal microscopy and scanning electron microscopy showed that the ratio of NET-releasing cells decreased in response to incubation with PA. Autophagy is a potential key intermediate process in the regulation of NET by PA. To investigate the effect of PA on autophagy, we used chloroquine to block lysosomal degradation. Exogenous PA led to accumulation of sequestosome-1 and microtubule-associated protein 1 light chain 3-II, and no further accumulation in the presence of chloroquine, all of which suggested an impairment of autophagic flux. To verify the role of autophagy in NET, we used rapamycin to promote autophagic flux; 100 nM rapamycin attenuated the suppressive effect of PA on NET release indicated by greater dsDNA levels, accumulation of citrullinated histone, and ratio of NET-releasing neutrophils. Overall, these data demonstrate PA inhibits NET release by suppressing autophagic flux, which provides information for understanding the immune dysfunction in postpartum cows.

Glycolysis, monocarboxylate transport, and purinergic signaling are key events in Eimeria bovis-induced NETosis

The protozoan parasite Eimeria bovis is the causative agent of bovine coccidiosis, an enteric disease of global importance that significantly affects cattle productivity. Previous studies showed that bovine NETosis—an important early host innate effector mechanism of polymorphonuclear neutrophil (PMN)—is elicited by E. bovis stages. So far, the metabolic requirements of E. bovis-triggered NET formation are unknown. We here studied early glycolytic and mitochondrial responses of PMN as well as the role of pH, distinct metabolic pathways, P2 receptor-mediated purinergic signaling, and monocarboxylate transporters 1 and 2 (MCT1, MCT2) in E. bovis sporozoite-induced NET formation. Seahorse-based experiments revealed a rapid induction of both neutrophil oxygen consumption rate (OCR) and early glycolytic responses, thereby reflecting immediate PMN activation and metabolic changes upon confrontation with sporozoites. The impact of these metabolic changes on NET formation was studied via chemical inhibition experiments targeting glycolysis and energy generation by the use of 2-fluor-2-deoxy-D-glucose (FDG), 6-diazo-5-oxo-L-norleucin (DON), sodium dichloroacetate (DCA), oxythiamine (OT), sodium oxamate (OXA), and oligomycin A (OmA) to block glycolysis, glutaminolysis, pyruvate dehydrogenase kinase, pyruvate dehydrogenase, lactate dehydrogenase, and mitochondrial ATP-synthase, respectively. Overall, sporozoite-induced NET formation was significantly diminished via PMN pretreatments with OmA and OXA, thereby indicating a key role of ATP- and lactate-mediated metabolic pathways. Consequently, we additionally studied the effects of extracellular pH, MCT1, MCT2, and purinergic receptor inhibitors (AR-C141900, AR-C155858, theobromine, and NF449, respectively). Pretreatment with the latter inhibitors led to blockage of sporozoite-triggered DNA release from exposed bovine PMN. This report provides first evidence on the pivotal role of carbohydrate-related metabolic pathways and purinergic receptors being involved in E. bovis sporozoite-induced NETosis.

The changing landscape of immune cells in the fetal mouse testis

Fetal testis growth involves cell influx and extensive remodeling. Immediately after sex determination in mouse, macrophages enable normal cord formation and removal of inappropriately positioned cells. This study provides new information about macrophages and other immune cells after cord formation in fetal testes, including their density, distribution, and close cellular contacts. C57BL6J mouse testes from embryonic day (E) 13.5 to birth (post-natal day 0; PND0), were examined using immunofluorescence, immunohistochemistry, and RT-qPCR to identify macrophages (F4/80, CD206, MHCII), T cells (CD3), granulocytes/neutrophils (Ly6G), and germ cells (DDX4). F4/80⁺ cells were the most abundant, comprising 90% of CD45⁺ cells at E13.5 and declining to 65% at PND0. Changes in size, shape, and markers (CD206 and MHCII) documented during this interval align with the understanding that F4/80⁺ cells have different origins during embryonic life. CD3⁺ cells and F4/80⁻/MHCII⁺ were absent to rare until PND0. Ly6G⁺ cells were scarce at E13.5 but increased robustly by PND0 to represent half of the CD45⁺ cells. These immunofluorescence data were in accord with transcript analysis, which showed that immune marker mRNAs increased with testis age. F4/80⁺ and Ly6G⁺ cells were frequently inside cords adjacent to germ cells at E13.5 and E15.5. F4/80⁺ cells were often in clusters next to other immune cells. Macrophages inside cords at E13.5 and E15.5 (F4/80^Hi/CD206⁺) were different from macrophages at PND0 (F4/80^Dim/CD206⁻), indicating that they have distinct origins. This histological quantification coupled with transcript information identifies new cellular interactions for immune cells in fetal testis morphogenesis, and highlights new avenues for studies of their functional significance.

Sodium butyrate attenuates bovine mammary epithelial cell injury by inhibiting the formation of neutrophil extracellular traps

Neutrophil extracellular traps (NETs) are an important means by which the body fights against exogenous bacteria. However, studies have shown that excessive NETs release can damage other cells. Accumulating evidence has shown that butyric acid can alleviate the inflammatory response of cells. However, the effect of butyric acid on Staphylococcus aureus-induced NETs formation and its underlying mechanism are still unclear. In this study, western blotting, immunofluorescence and CCK-8 assays were used to examine the effect of NETs formation by sodium butyrate (NaB). The results showed that NaB suppressed the release of S. aureus-induced NETs formation, as indicated by decreases in the levels of DNA, histones, myeloperoxidase, and neutrophil elastase. S. aureus can induce autophagy, and autophagy plays a key role in the formation of NETs. Our data showed that NaB activated mammalian target of rapamycin (mTOR) and the kinases protein kinase B (AKT) and unc-51 like kinase 1 (ULK1) at Ser757 and inhibited AMP-activated protein kinase (AMPK). To explore whether NaB inhibited the formation of NETs by inhibiting autophagy, we added 3-methyladenine (autophagy inhibitor) (3-MA, 5 mM) to bovine neutrophils, and the results showed that 3-MA significantly inhibited NETs release. Furthermore, we found that NETs and their component histones exhibited significantly increased the cytotoxic effects on bovine mammary epithelial cells (BMECs), indicating that NETs and their component histones play a key role in BMEC damage. In conclusion, NaB can reduce the excessive formation of NETs by inhibiting autophagy, thus reducing the damaging effect of NETs on BMECs.

Neutrophil Extracellular Traps and Pancreatic Cancer Development: A Vicious Cycle

Neutrophil extracellular traps (NETs) are a neutrophil-generated extracellular network of chromatin and chromatin-bound molecules with antimicrobial potency. Recent data suggest that NETs are associated with cancer progression and cancer-associated hypercoagulability. Pancreatic adenocarcinoma (PDAC) is a lethal type of cancer in which hypercoagulability and cancer-related thrombosis are among the main complications. In the current report, we summarize the available data on the interplay between NET formation and PDAC development. We conclude that NETs support a dual role during PDAC progression and metastasis. Their formation is on the one hand an important event that shapes the cancer microenvironment to support cancer cell proliferation, invasion and metastasis. On the other hand, NETs may lead to cancer-associated thrombosis. Both mechanisms seem to be dependent on distinct molecular mechanisms that link inflammation to cancer progression. Collectively, NET formation may contribute to the pathogenesis of PDAC, while during cancer development, the proinflammatory environment enables the induction of new NETs and thrombi, forming a vicious cycle. We suggest that targeting NET formation may be an effective mechanism to inhibit both PDAC development and the accompanying hypercoagulability.

Pamidronate, a promising repositioning drug to treat leishmaniasis, displays antileishmanial and immunomodulatory potential

Visceral leishmaniasis (VL) is an infectious disease caused by Leishmania infantum (L. infantum). Currently, there are no vaccines and/or prophylactic therapies against VL, and the recentpharmacological approaches come from the drug repositioning strategy. Here, we evaluated the anticancer drug pamidronate (PAM) to identify a new therapeutic option for the treatment of human VL. We assessed its in vitro antileishmanial activity against the promastigote and amastigote forms of L. infantum by evaluating cell cytotoxicity. The antileishmanial and immunomodulatory activities were assessed using human peripheral blood leukocytes ex vivo. PAM induced the formation of vacuoles in the cytoplasm of the promastigotes and alterations in the morphology of the kinetoplast and mitochondria in vitro, which indicates anti-promastigote activity. PAM also reduced the number of infected macrophages and intracellular amastigotes in a concentration-dependent manner, with cell viability above 70%. In ex vivo, PAM reduced the internalized forms of L. infantum in the classical monocyte subpopulation. Furthermore, it enhanced IL-12 and decreased IL-10 and TGF-β by monocytes and neutrophils. Increased IFN-γ and TNF levels for CD8^- and CD8⁺ T lymphocytes and B lymphocytes, respectively, were observed after the treatment with PAM, as well as a reduction in IL-10 by the lymphocyte subpopulations evaluated. Taken together, our results suggest that PAM may be eligible as a potential therapeutic alternative for drug repurposing to treat human visceral leishmaniasis.

Treponema pallidum delays the apoptosis of human polymorphonuclear neutrophils through the intrinsic and extrinsic pathways

Treponema pallidum is a "stealth pathogen" responsible for infectious sexually transmitted diseases. Although neutrophils are usually present in skin lesions of early syphilis, the role of these cells in T. pallidum infection has barely been investigated. Neutrophils are short-lived cells that undergo constitutive apoptosis, and phagocytosis usually accelerates this process. Here, we demonstrated that human polymorphonuclear neutrophils (hPMNs) could phagocytose T. pallidum in vitro. An unexpected discovery was that T. pallidum inhibited hPMNs apoptosis markedly in an opsonin-independent manner. Furthermore, this phenomenon was not affected by bacterial viability, as detected by annexin V, morphology studies, and TUNEL staining. Exploration of the underlying mechanism showed that expression of the cleaved forms of caspase-3, -8, and -9 and effector caspase activity were diminished significantly in T. pallidum-infected hPMNs. T. pallidum also impaired staurosporine- and anti-Fas-induced signaling for neutrophil apoptosis. Of note, these effects were accompanied by inducing the autocrine production of the anti-apoptotic cytokine IL-8. Taken together, our data revealed that T. pallidum could inhibit the apoptosis of hPMNs through intrinsic and extrinsic pathways and provide new insights for understanding the pathogenicity mechanisms of T. pallidum.

Research progress of BK virus and systemic lupus erythematosus

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease in which patients are often infected by viruses due to deficient immunity or immunosuppressant use. BK virus (BKV)mainly affects the kidney and can also cause multiple organ involvement throughout the body, which is similar to SLE. BKV is mostly a latent infection in vivo. The incidence of virus reactivation is higher in SLE patients. Reactivation of BKV can induce the production of autoantibodies, thereby promoting the occurrence and development of SLE.Purpose: Aim of this article is to review the prevalence and pathegenesis of BKV infection in SLE patients.Method: The literature search was conducted using four different databases including PubMed, Cochrane Library, Scopus and Web of Science.Results: BK virus is higher infection and reactivation in SLE patients. The "hapten carrier" mechanism may lead to the production of autoantibodies. Some immunosuppressive drugs, like leflumide and hydroxychloroquine, may show a protective effect.Conclusions: BKV infection plays a role in the occurrence and development of SLE, and its significance deserves further exploration.

Intestinal organoids in coculture: redefining the boundaries of gut mucosa ex vivo modeling

All-time preservation of an intact mucosal barrier is crucial to ensuring intestinal homeostasis and, hence, the organism's overall health maintenance. This complex process relies on an equilibrated signaling system between the intestinal epithelium and numerous cell populations inhabiting the gut mucosa. Any perturbations of this delicate cross talk, particularly regarding the immune cell compartment and microbiota, may sustainably debilitate the intestinal barrier function. As a final joint event, a critical rise in epithelial permeability facilitates the exposure of submucosal immunity to microbial antigens, resulting in uncontrolled inflammation, collateral tissue destruction, and dysbiosis. Organoid-derived intestinal coculture models have established themselves as convenient tools to reenact such pathophysiological events, explore interactions between selected cell populations, and assess their roles with a central focus on intestinal barrier recovery and stabilization.

Effect of quercetin on formation of porcine neutrophil extracellular trap

Neutrophil extracellular trap (NET) formation is an immune response to the invasion of external microorganisms. Quercetin, a member of the flavonoid family found in fruits and vegetables, has been examined in multiple biological contexts. The objective of this study was to examine the effect of quercetin on porcine NET formation. We measured NET formation by peripheral blood polymorphonuclear cells (PMNs) using propidium iodide (PI) dye. The amount of tumor necrosis factor (TNF)-α in culture supernatants was quantified by ELISA, and TNF-α mRNA expression was measured by RT-PCR. Direct treatment of PMNs with quercetin did not affect NET formation; however, NET formation was inhibited by exposure to culture supernatant from peripheral blood mononuclear cells (PBMCs) treated with quercetin. By contrast, culture supernatant from PBMCs treated with lipopolysaccharide (LPS) induced high levels of NET formation of PMNs, and this effect was reduced by co-treatment with LPS and quercetin. In addition, treatment of PMNs with recombinant porcine (rp) TNF-α induced high levels of NET formation. PBMCs treated with LPS increased higher levels of TNF-α mRNA and protein, but this effect was weakened when they were co-treated with quercetin. These findings indicated that quercetin inhibits NET formation of PMNs by suppressing production of TNF-α from LPS-stimulated PBMCs. These results suggest that quercetin exerts an anti-inflammatory effect, mediated by down-regulation of TNF-α production from LPS-stimulated PBMCs, which inhibits NET formation in PMNs.

The Role of Neutrophil NETosis in Organ Injury: Novel Inflammatory Cell Death Mechanisms

NETosis is a type of regulated cell death dependent on the formation of neutrophil extracellular traps (NET), where net-like structures of decondensed chromatin and proteases are produced by polymorphonuclear (PMN) granulocytes. These structures immobilise pathogens and restrict them with antimicrobial molecules, thus preventing their spread. Whilst NETs possess a fundamental anti-microbial function within the innate immune system under physiological circumstances, increasing evidence also indicates that NETosis occurs in the pathogenic process of other disease type, including but not limited to atherosclerosis, airway inflammation, Alzheimer’s and stroke. Here, we reviewed the role of NETosis in the development of organ injury, including injury to the brain, lung, heart, kidney, musculoskeletal system, gut and reproductive system, whilst therapeutic agents in blocking injuries induced by NETosis in its primitive stages were also discussed. This review provides novel insights into the involvement of NETosis in different organ injuries, and whilst potential therapeutic measures targeting NETosis remain a largely unexplored area, these warrant further investigation.

Serum CXCL1 Is a Prognostic Factor for Patients With Hepatitis B Virus-Related Acute-On-Chronic Liver Failure

Purpose: Neutrophils and cytokines play a major role in the pathogenesis of acute-on-chronic liver failure (ACLF). We aimed to determine whether chemokine (CXC) ligand 1 (CXCL1), a key marker of neutrophil recruitment and activation, could predict the severity and prognosis of hepatitis B virus–related ACLF (HBV-ACLF).

Methods: Hospitalized patients with HBV-ACLF were enrolled in a prospective study and stratified as survivors (alive at 28 days) and nonsurvivors (deceased at 28 days). Serum CXCL1 levels were measured in healthy controls, patients with chronic HBV, patients with HBV-related compensated cirrhosis, and patients with HBV-ACLF. Univariate and multivariable logistic analyses, Pearson correlation analysis, area under the receiver operating characteristic curve (AUROC), and Z tests were used to evaluate the performance of CXCL1 as a marker in HBV-ACLF.

Results: Patients with HBV-ACLF had significantly higher serum levels of CXCL1 and neutrophil count than healthy controls and patients with chronic HBV or HBV-related compensated cirrhosis (P < 0.01, respectively). Among patients with HBV-ACLF, survivors had lower serum CXCL1 levels and neutrophil count than those of nonsurvivors (P < 0.001, P < 0.05, respectively). Serum CXCL1 level was positively correlated with neutrophil count (r = 0.256, P = 0.001), ACLF grade (r = 0.295, P < 0.001) and organ failure, including coagulation (r = 0.21, P = 0.005) and brain failure (r = 0.198, P = 0.008). Multivariable logistic analyses showed serum CXCL1 [OR (95% CI) = 1.017 (1.009–1.025), P < 0.001] was an independent risk factor for 28-day mortality in HBV-ACLF. Meanwhile, the AUROC analysis demonstrated that serum CXCL1 [0.741 (0.669–0.804)] might be a reliable prognostic biomarker for patients with HBV-ACLF.

Conclusions: Overall, serum CXCL1 can serve as a biomarker indicating the severity of disease and prognosis for patients with HBV-ACLF. CXCL1 might also be a therapeutic target in this disease.

Neutrophil Extracellular Traps in Colorectal Cancer Progression and Metastasis

Neutrophils form sticky web-like structures known as neutrophil extracellular traps (NETs) as part of innate immune response. NETs are decondensed extracellular chromatin filaments comprising nuclear and cytoplasmic proteins. NETs have been implicated in many gastrointestinal diseases including colorectal cancer (CRC). However, the regulatory mechanisms of NET formation and potential pharmacological inhibitors in the context of CRC have not been thoroughly discussed. In this review, we intend to highlight roles of NETs in CRC progression and metastasis as well as the potential of targeting NETs during colon cancer therapy.

For Better or for Worse: A Look Into Neutrophils in Traumatic Spinal Cord Injury

Neutrophils are short-lived cells of the innate immune system and the first line of defense at the site of an infection and tissue injury. Pattern recognition receptors on neutrophils recognize pathogen-associated molecular patterns or danger-associated molecular patterns, which recruit them to the destined site. Neutrophils are professional phagocytes with efficient granular constituents that aid in the neutralization of pathogens. In addition to phagocytosis and degranulation, neutrophils are proficient in creating neutrophil extracellular traps (NETs) that immobilize pathogens to prevent their spread. Because of the cytotoxicity of the associated granular proteins within NETs, the microbes can be directly killed once immobilized by the NETs. The role of neutrophils in infection is well studied; however, there is less emphasis placed on the role of neutrophils in tissue injury, such as traumatic spinal cord injury. Upon the initial mechanical injury, the innate immune system is activated in response to the molecules produced by the resident cells of the injured spinal cord initiating the inflammatory cascade. This review provides an overview of the essential role of neutrophils and explores the contribution of neutrophils to the pathologic changes in the injured spinal cord.

In Vivo and In Vitro Impairments in T Helper Cell and Neutrophil Responses against Mucor irregularis in Card9 Knockout Mice

Mucor irregularis is a frequently found fungus in Asia, especially China, and it causes primary cutaneous mucormycosis with a high rate of disfigurement. Caspase recruitment domain-containing protein 9 (Card9) is an essential adaptor molecule downstream of C-type lectin receptors. It mediates the activation of nuclear factor kappa B (NF-κB), regulates T helper 1 (Th1) and Th17 differentiation, and plays an important role in fungal immune surveillance. CARD9 deficiency correlates with the increased susceptibility to many fungal infections, including cutaneous mucormycosis caused by M. irregularis However, the underlying immunological mechanisms were not elucidated. Our study established a murine model of subcutaneous M. irregularis infection, and we isolated immune cells, including bone marrow-derived macrophages, bone marrow-derived dendritic cells, naive T cells, and neutrophils, from wild-type (WT) and Card9 knockout (Card9^-/- ) mice to examine the antifungal effect of Card9 on M. irregularis in vivo and in vitro Card9^-/- mice exhibited increased susceptibility to M. irregularis infection. Impaired local cytokine and chemokine production, NF-κB (p65) activation, and Th1/17 cell differentiation and partially impaired neutrophil-dependent antifungal immunity were observed in Card9^-/- mice. This work enriches our knowledge of the relationship between CARD9 deficiency and mucormycosis.

Neutrophils: Need for Standardized Nomenclature

Neutrophils are the most abundant innate immune cell with critical anti-microbial functions. Since the discovery of granulocytes at the end of the nineteenth century, the cells have been given many names including phagocytes, polymorphonuclear neutrophils (PMN), granulocytic myeloid derived suppressor cells (G-MDSC), low density neutrophils (LDN) and tumor associated neutrophils (TANS). This lack of standardized nomenclature for neutrophils suggest that biologically distinct populations of neutrophils exist, particularly in disease, when in fact these may simply be a manifestation of the plasticity of the neutrophil as opposed to unique populations. In this review, we profile the surface markers and granule expression of each stage of granulopoiesis to offer insight into how each stage of maturity may be identified. We also highlight the remarkable surface marker expression profiles between the supposed neutrophil populations.

Circulatory markers of immunity and carotid atherosclerotic plaque

BACKGROUND AND AIMS

We aimed to determine the association of circulatory markers of innate and adaptive immunity with carotid atherosclerotic plaque characteristics.

METHODS

In 1602 participants from the population-based Rotterdam Study with subclinicalcarotid atherosclerosis, blood sampling was performed to determine granulocyte, platelet, monocyte (innate immunity) and lymphocyte (adaptive immunity) counts, from which the granulocyte-to-lymphocyte ratio [GLR], platelet-to-lymphocyte ratio [PLR], monocyte-to-lymphocyte ratio [MLR] and systemic immune-inflammation index [SII] were calculated. All participants underwent carotid MRI for evaluation of plaque characteristics. Plaque size (stenosis >30%, maximum plaque thickness) and plaque composition (presence of intraplaque hemorrhage [IPH], lipid-rich necrotic core [LRNC], and calcification) were assessed. Using linear and logistic regression models, the association of innate and adaptive immunity markers with plaque size and plaque components, adjusting for relevant confounders, was assessed.

RESULTS

Higher levels of granulocytes were significantly associated with larger plaque thickness (mean difference [Ln (mm)] per Ln increase granulocyte count [95% CI]: 0.06 [0.02; 0.10]). Conversely, more lymphocytes related with smaller maximum plaque thickness (mean difference [Ln (mm)] per Ln increase lymphocyte count: 0.09 [-0.14;-0.04]) and a lower prevalence of IPH (odds ratio per Ln increase lymphocyte count: 0.60 [0.37; 0.97]). Moreover, all ratio measures were associated with larger plaque thickness, of which the MLR also associated with more frequent LRNC (odds ratio per Ln increase MLR: 1.26 [1.02; 1.56]).

CONCLUSIONS

The innate immunity links to larger plaques, whilst the adaptive immunity seems to relate to smaller plaques and a lower frequency of IPH. These results suggest that an imbalance in innate and adaptive immunity may play a role in the vulnerability of carotid atherosclerotic plaques.

Protein A Modulates Neutrophil and Keratinocyte Signaling and Survival in Response to Staphylococcus aureus

The type 1 TNF-α receptor (TNFR1) has a central role in initiating both pro-inflammatory and pro-apoptotic signaling cascades in neutrophils. Considering that TNFR1 signals Staphylococcus aureus protein A (SpA), the aim of this study was to explore the interaction of this bacterial surface protein with neutrophils and keratinocytes to underscore the signaling pathways that may determine the fate of these innate immune cells in the infected tissue during staphylococcal skin infections. Using human neutrophils cultured in vitro and isogenic staphylococcal strains expressing or not protein A, we demonstrated that SpA is a potent inducer of IL-8 in neutrophils and that the induction of this chemokine is dependent on the SpA-TNFR1 interaction and p38 activation. In addition to IL-8, protein A induced the expression of TNF-α and MIP-1α highlighting the importance of SpA in the amplification of the inflammatory response. Protein A contributed to reduce neutrophil mortality prolonging their lifespan upon the encounter with S. aureus. Signaling initiated by SpA modulated the type of neutrophil cell death in vitro and during skin and soft tissue infections (SSTI) in vivo triggering the apoptotic pathway instead of necrosis. Moreover, SpA induced pro-inflammatory cytokines in keratinocytes, modulating their survival in vitro and preventing the exacerbated necrosis and ulceration of the epithelium during SSTI in vivo. Taken together, these results highlight the importance of the inflammatory signaling induced by protein A in neutrophils and skin epithelial cells. The ability of protein A to modulate the neutrophil/epithelial cell death program in the skin is of clinical relevance considering that lysis of neutrophils and epithelial cells will promote an intense inflammatory response and contribute to tissue damage, a non-desirable feature of complicated SSTI.