The humoral pattern recognition receptor PTX3 is stored in neutrophil granules and localizes in extracellular traps

Pentraxin 3 stability in serum and urine samples at -20 °C during a 4-week period

INTRODUCTION

The aim of our study was to examine the stability of pentraxin 3 (PTX3) in serum and urine samples during 4-week storage at -20 °C.

METHODS

Ten routine leftover serum and urine samples were used in this study. The samples were stored at -20 °C over 4 weeks and analyzed each week in a single batch using the Human pentraxin 3 ELISA kit (BioVendor Group). Stability was expressed as a percentage difference between the initial measurement and the measurements taken weekly. Total error (33%) was used as the performance criterion for stability.

RESULTS

The concentration of PTX3 decreases with time during storage at -20 °C in both serum and urine. The percentage difference exceeded the set criterion in serum samples at the third week of storage (percentage difference = -23.5% [95% CI, -36.6% to -10.5%]) and at the first week of storage in urine samples (percentage difference = -41.5% [95% CI, -63.1% to ‒19.8%]).

DISCUSSION

Pentraxin 3 can be stored in serum samples for a maximum of 2 weeks at -20 °C before analysis to measure representative results. Because PTX3 is not stable in urine samples, such samples should be analyzed on the day of sample collection.

Exploratory study on reference intervals of calprotectin and pentraxin 3

IntroductionThe aim of our study was to determine reference intervals for serum pentraxin 3 and calprotectin, as well as for urine calprotectin according to the CLSI EP28-A3C guidelines for defining, establishing, and verifying reference intervals in the clinical laboratory.Materials and methodsA total of 120 serum and urine samples from either healthy volunteers or outpatients were used for reference interval establishment. The participants had CRP levels, leucocyte counts, serum urea levels, creatinine levels, and estimated glomerular filtration rates (CKD-EPI eGFRs) within the reference range and no medical history of acute/chronic inflammatory diseases/conditions or cancer. Calprotectin was measured via a commercially available turbidimetric method - the Bühhlmann fCAL® Turbo Reagent Kit - while pentraxin 3 was measured using the Human Pentraxin 3 ELISA Kit from the BioVendor Group.ResultsThe serum calprotectin reference range was ≤3.6 mg/L, the 90% CI for the upper reference range was 3.1-4.1 mg/L, while the serum pentraxin 3 reference concentration was ≤3.0 µg/L, and the 90% CI for the upper reference range being 2.7-3.2 µg/L. Additionally, the urinary calprotectin concentration was ≤1.4 mg/L, with a 90% CI for the upper reference range of 1.0-1.7 mg/L.ConclusionThis study reports sample and method-specific reference intervals for the detection of various inflammatory conditions.

Suramin Exerts an Ameliorative Effect on Acetic Acid-Induced Acute Colitis in Rats by Demonstrating Potent Antioxidant and Anti-Inflammatory Properties

Background and Objectives: The purpose of this study was to evaluate potential protective effects of suramin on inflammation, oxidative stress, and histopathological damage a rat model of acute colitis created with acetic acid. Materials and Methods: Wistar albino (male) rats were randomly assigned to three groups: control (n = 10), colitis + saline (n = 10), and colitis + suramin (n = 10). Rectal instillation of 4% acetic acid was used to induce acute colitis. Suramin (10 mg/kg/day) or saline was administered intraperitoneally for 15 days. Plasma concentrations of pentraxin 3 (PTX3), tumor necrosis factor-alpha (TNF-α), neutrophil extracellular traps (NETs), and malondialdehyde (MDA) were determined using enzyme-linked immunosorbent assay (ELISA) and spectrophotometric methods. In addition, vascular endothelial growth factor (VEGF) and TNF-α levels in colonic tissue were also measured. Histopathological evaluations were conducted using hematoxylin and eosin staining. Results: Significant increases in plasma and tissue inflammatory markers, oxidative stress parameters, and histopathological scores were observed when compared to control group; values were higher in colitis group. Suramin treatment significantly reduced plasma PTX3, TNF-α, NETs, and MDA levels, and colonic TNF-α and VEGF concentrations compared to the untreated colitis group. Histological analysis showed reduced epithelial injury and leukocyte presence in rats receiving suramin. Conclusions: Our findings demonstrate that suramin significantly attenuates inflammatory and oxidative damage in an experimental model of acute colitis. These results suggest that suramin may possess therapeutic potential in intestinal inflammation; however, this effect requires further support through advanced experimental and clinical studies.

Pentraxin 3 is a Novel Inflammatory Marker of HLA-B27-associated Uveitis

PURPOSE

Evidence exists that pentraxin 3 (PTX3) is involved in the pathogenesis of autoimmune diseases. The aim of this study was to analyze the levels of PTX3 in aqueous humor (AH) samples from patients with specific autoimmune uveitic entities. In addition, we correlated PTX3 levels with the levels of proinflammatory cytokines and chemokines and the clinical disease activity.

METHODS

AH samples from patients with active uveitis associated with human leukocyte antigen (HLA)-B27-related inflammation (n = 12), Behçet's disease (BD) (n = 13), Vogt-Koyanagi-Harada (VKH) disease (n = 12), sarcoidosis (n = 8) and control subjects (n = 9) were measured with the use of multiplex assays.

RESULTS

When considering all uveitis patients as one group (n = 45), PTX3 levels were significantly increased compared to controls (p = 0.002). When comparing the four individual disease groups to controls, PTX3 levels were significantly higher in only HLA-B27-associated uveitis (p < 0.001). PTX3 levels were significantly higher in patients with HLA-B27-associated uveitis than in patients with BD (p = 0.034) and VKH disease (p < 0.001). PTX3 levels had a significant correlation with clinical disease activity (r = 0.480; p = 0.001) and strong positive correlations with aqueous humor levels of interferon-γ (r = 0.749; p < 0.001), interleukin (IL)-1ß (r = 0.804; p < 0.001), IL-6 (r = 707; p < 0.001), CCL20 (r = 0.691; p < 0.001) and CXCL8 (r = 0.775; p < 0.001).

CONCLUSIONS

PTX3 is an inflammatory marker and might exert a pathogenic role in HLA-B27-associated uveitis.

Anti-pentraxin 3 antibodies and residual disease activity in rheumatoid arthritis

OBJECTIVES

This study quantified anti-PTX3 antibodies in the serum of seropositive and seronegative RA patients, examining their associations with disease activity and patient-reported outcome measures (PROMs).

METHODS

In this cross-sectional study, RA patients diagnosed per ACR/EULAR 2010 criteria were recruited. Seronegative RA was defined as ACPA <7 kU/L. Data on demographics, clinical characteristics, medications, and PROMs were collected. Serum anti-PTX3 antibodies were measured using an in-house ELISA method. Comparative analyses were conducted with historical controls having PsA and FM.

RESULTS

The cohort included 83 RA patients (42 seropositive, 41 seronegative). Seropositive patients had lower anti-PTX3 antibody levels than PsA (P = 0.001) and FM (P = 0.004) controls. Seronegative patients had higher levels than seropositive ones (P = 0.032). Anti-PTX3 antibodies correlated with CDAI (r = 0.255), PtGA (r = 0.257), VAS-GH (r = -0.235), VAS-pain (r = 0.233), and HAQ (r = 0.311), but not with joint counts, inflammatory markers, or physician's global assessment. The PtGA association remained significant when adjusted for BMI, SJC28, ESR, and prednisone dosage (β = 0.206, P = 0.042). Patients with near-controlled RA (SJC28 ≤ 2, PtGA > 2) had higher anti-PTX3 levels than those with controlled disease (SJC28 ≤ 2, PtGA ≤ 2; P = 0.048). Tocilizumab or abatacept-treated patients had lower levels compared with those on TNFi or JAKi.

CONCLUSION

Elevated anti-PTX3 antibodies in RA indicate residual active disease despite controlled inflammation. They may serve as a biomarker for true active disease, especially in seronegative RA patients who might be undertreated.

Disulfide bonds-driven assembly and structural complexity of PTX3: High-resolution structures insights into multimeric architecture

Pentraxin-3 (PTX3) is a multifunctional pattern-recognition molecule that is essential for immune defense, pathogen recognition, and complement activation. PTX3 is stored as a monomer in neutrophil granules, and assembles into higher-order oligomers upon immune activation, thereby enhancing its antimicrobial function. The mechanism underlying this assembly remains elusive. In this study, we employed cryo-electron microscopy to resolve multiple high-resolution structures of PTX3 in octameric and tetrameric forms, as well as medium-resolution structures in dimeric and hexameric forms. Structural analysis revealed that PTX3 oligomerization is driven by dimeric units stabilized by C-terminal interchain disulfide bonds, and the N-terminal disulfide bonds facilitate further assembly into larger oligomers. This hierarchical assembly is crucial for the activation of the classical complement pathway. These findings offer critical insights into the assembly mechanisms and structural complexity of PTX3 and pave the way for novel therapeutic developments targeting PTX3.

Pentraxin 3: a novel biomarker in pediatric central nervous system infections

BACKGROUND

Pediatric CNS infections have been identified as a global health problem, associated with an increased death rate and fatal consequences. Pentraxin 3 (PTX3) is an acute-phase mediator that increases in body fluids and plasma throughout inflammation. Our study was designed to assess the diagnostic and prognostic value of cerebrospinal fluid (CSF) PTX3 levels in pediatric patients with different central nervous system (CNS) infections.

METHODS

We enrolled 100 children hospitalized at Fayoum University Children's Hospital with suspected CNS infections fulfilling the case criteria for CNS infections. We recorded their medical history and examination data upon admission. The C-reactive protein (CRP) level, complete blood count (CBC), CSF PTX3 level, CSF analysis and culture, and blood culture were assessed in all patients at the time of admission.

RESULTS

Levels of PTX3 were significantly correlated with the duration of symptoms before admission, length of hospital stay, patient outcomes, CRP levels, CSF findings, and CSF cultures (P value < 0.001). Patients who needed mechanical ventilation or experienced adverse outcomes had greater levels of PTX3, which were more prevalent in those with a bacterial etiology (P value < 0.05).

CONCLUSION

PTX3 indicates disease severity and prognosis. PTX3 showed statistically significant sensitivity when discriminating between bacterial and aseptic CNS infections, as well as between bacterial CNS infections and controls. However, it has lower sensitivity and specificity than other CSF biomarkers, though it is higher than serum CRP.

PTX3 is expressed in terminal lymphatics and shapes their organization and function

Introduction

The lymphatic system is a multifaceted regulator of tissue homeostasis and an integral part of immune responses. Previous studies had shown that subsets of lymphatic endothelial cells (LEC) express PTX3, an essential component of humoral innate immunity and tissue homeostasis.

Methods

In the present study using whole-mount imaging and image-based morphometric quantifications, Ptx3-targeted mice and in vivo functional analysis, we investigated the involvement of PTX3 in shaping and function of the lymphatic vasculature.

Results

We found that PTX3 is localized in the extracellular matrix (ECM) surrounding human and murine lymphatic vessels (LV). In murine tissues, PTX3 was localized in the ECM close to LV terminals and sprouting. Ptx3-deficient mice showed LV abnormalities in the colon submucosa and diaphragm, including a disorganized pattern and hyperplasia of initial LV capillaries associated with altered distribution of tight junction-associated molecules. Mice with LEC-restricted PTX3 gene inactivation showed morphological and organization abnormalities similar to those observed in Ptx3-deficient animals. Ptx3-deficient mice showed defective fluid drainage from footpads and defective dendritic cell (DC) trafficking.

Discussion

Thus, PTX3 is strategically localized in the ECM of specialized LV, playing an essential role in their structural organization and immunological function.

Prognostic Value of Pentraxin3 Protein Expression in Human Malignancies: A Systematic Review and Meta-Analysis

BACKGROUND/OBJECTIVES

Pentraxin 3 (PTX3), a member of the pentraxin superfamily, plays diverse roles in immunity and inflammation. Its dual role in tumorigenesis, exhibiting both protumoral and antitumoral effects, has been the subject of conflicting reports. High PTX3 expression levels in serum and tumor tissues have been associated with poor prognosis in various malignancies, suggesting its potential as a prognostic biomarker. Through this meta-analysis, we aim to comprehensively assess the prognostic significance of PTX3 protein expression in human malignancies and evaluate its potential as a pan-cancer prognostic marker.

METHODS

A systematic literature search was conducted across the PubMed, Embase, Web of Science, MEDLINE, and Cochrane Library databases. Studies were included if they assessed the association between PTX3 protein expression and overall survival (OS) in cancer patients. Hazard ratios (HRs) were pooled using a random-effects model. Subgroup analyses were performed based on the method of PTX3 assessment, and publication bias was evaluated using Egger's and Begg's tests.

RESULTS

Nine studies encompassing 1215 patients were included in the analysis. High PTX3 expression was significantly associated with poorer OS (HR = 1.89, 95% CI = 1.55-2.32, p < 0.01) with no significant heterogeneity (I2 = 0%). Subgroup analysis revealed consistent results across different assessment methods (immunohistochemistry: HR = 1.93, p < 0.01; immunoassay: HR = 1.86, p < 0.01). However, publication bias was detected (Egger's test, p = 0.03).

CONCLUSIONS

High PTX3 protein expression is associated with a poor prognosis in various malignancies, supporting its potential as a prognostic biomarker.

High glucose induces DNA methyltransferase 1 dependent epigenetic reprogramming of the endothelial exosome proteome in type 2 diabetes

In response to hyperglycemia, endothelial cells (ECs) release exosomes with altered protein content and contribute to paracrine signalling, subsequently leading to vascular dysfunction in type 2 diabetes (T2D). High glucose reprograms DNA methylation patterns in various cell/tissue types, including ECs, resulting in pathologically relevant changes in cellular and extracellular proteome. However, DNA methylation-based proteome reprogramming in endothelial exosomes and associated pathological implications in T2D are not known. Hence, in the present study, we used Human umbilical vein endothelial cells (HUVECs), High Fat Diet (HFD) induced diabetic mice (C57BL/6) and clinical models to understand epigenetic basis of exosome proteome regulation in T2D pathogenesis . Exosomes were isolated by size exclusion chromatography and subjected to tandem mass tag (TMT) labelled quantitative proteomics and bioinformatics analysis. Immunoblotting was performed to validate exosome protein signature in clinically characterized individuals with T2D. We observed ECs cultured in high glucose and aortic ECs from HFD mouse expressed elevated DNA methyltransferase1 (DNMT1) levels. Quantitative proteomics of exosomes isolated from ECs treated with high glucose and overexpressing DNMT1 showed significant alterations in both protein levels and post translational modifications which were aligned to T2D associated vascular functions. Based on ontology and gene-function-disease interaction analysis, differentially expressed exosome proteins such as Thrombospondin1, Pentraxin3 and Cystatin C related to vascular complications were significantly increased in HUVECs treated with high glucose and HFD animals and T2D individuals with higher levels of glycated hemoglobin. These proteins were reduced upon treatment with 5-Aza-2'-deoxycytidine. Our study shows epigenetic regulation of exosome proteome in T2D associated vascular complications.

Modulation of diabetes-related retinal pathophysiology by PTX3

Diabetic retinopathy (DR) is a common complication of diabetes characterized by vascular pathology and neuroinflammation. Pentraxin 3 (PTX3) is a soluble pattern recognition molecule that functions at the crossroads between innate immunity, inflammation, and tissue remodeling. DR is known to involve inflammatory pathways, although the potential relevance of PTX3 has not been explored. We found that PTX3 protein levels increased in the retina of diabetic mice. Similarly, evaluation of a publicly available transcriptomic human dataset revealed increased PTX3 expression in DR with diabetic macular edema and proliferative retinopathy, when compared to nondiabetic retinas or diabetic retinas without complications. To further understand the role of PTX3 within DR, we employed the streptozotocin-induced diabetes model in PTX3 knockout mice (PTX3KO), which were followed up for 9 mo to evaluate hallmarks of disease progression. In diabetic PTX3KO mice, we observed decreased reactive gliosis, diminished microglia activation, and reduced vasodegeneration, when compared to diabetic PTX3 wild-type littermates. The decrease in DR-associated pathological features in PTX3KO retinas translated into preserved visual function, as evidenced by improved optokinetic response, restored b-wave amplitude in electroretinograms, and attenuated neurodegeneration. We showed that PTX3 induced an inflammatory phenotype in human retinal macroglia, characterized by GFAP upregulation and increased secretion of IL6 and PAI-1. We confirmed that PTX3 was required for TNF-α-induced reactive gliosis, as PTX3KO retinal explants did not up-regulate GFAP in response to TNF-α. This study reveals a unique role for PTX3 as an enhancer of sterile inflammation in DR, which drives pathogenesis and ultimately visual impairment.

FcRider: a recombinant Fc nanoparticle with endogenous adjuvant activities for hybrid immunization

Active immunization (vaccination) induces long-lasting immunity with memory, which takes weeks to months to develop. Passive immunization (transfer of neutralizing antibodies) provides immediate protection, yet with high cost and effects being comparatively short-lived. No currently approved adjuvants are compatible with formulations to combine active and passive immunizations, not to mention their huge disparities in administration routes and dosage. To solve this, we engineered the Fc fragment of human IgG1 into a hexamer nanoparticle and expressed its afucosylated form in Fut8-/- CHO cells, naming it "FcRider." FcRider is highly soluble with long-term stability, easily produced at high levels equivalent to those of therapeutic antibodies, and is amenable to conventional antibody purification schemes. Most importantly, FcRider possesses endogenous adjuvant activities. Using SWHEL B cell receptor (BCR) transgenic mice, we found that HEL-FcRider induced GL7+ germinal center B cells and HEL-specific IgG. Similarly, immunizing mice with UFO-BG-FcRider, a fusion containing the stabilized human immunodeficiency virus-1 (HIV-1) Env protein as immunogen, promoted somatic hypermutation and generation of long CDR3 of the IgG heavy chains. Intramuscular injection of (Fba + Met6)3-FcRider, a fusion with two peptide epitopes from Candida albicans cell surface, stimulated strong antigen-specific IgG titers. In three different models, we showed that afucosylated FcRider functions as a multivalent immunogen displayer and stimulates antigen-specific B cells without any exogenous adjuvant. As an antibody derivative, afucosylated FcRider could be a novel platform combining vaccines and therapeutic antibodies, integrating active and passive immunizations into single-modality "hybrid immunization" to provide complete and long-lasting protection against infections, and may open new avenues in cancer immunotherapy as well.

Neutrophil extracellular traps in homeostasis and disease

Neutrophil extracellular traps (NETs), crucial in immune defense mechanisms, are renowned for their propensity to expel decondensed chromatin embedded with inflammatory proteins. Our comprehension of NETs in pathogen clearance, immune regulation and disease pathogenesis, has grown significantly in recent years. NETs are not only pivotal in the context of infections but also exhibit significant involvement in sterile inflammation. Evidence suggests that excessive accumulation of NETs can result in vessel occlusion, tissue damage, and prolonged inflammatory responses, thereby contributing to the progression and exacerbation of various pathological states. Nevertheless, NETs exhibit dual functionalities in certain pathological contexts. While NETs may act as autoantigens, aggregated NET complexes can function as inflammatory mediators by degrading proinflammatory cytokines and chemokines. The delineation of molecules and signaling pathways governing NET formation aids in refining our appreciation of NETs' role in immune homeostasis, inflammation, autoimmune diseases, metabolic dysregulation, and cancer. In this comprehensive review, we delve into the multifaceted roles of NETs in both homeostasis and disease, whilst discussing their potential as therapeutic targets. Our aim is to enhance the understanding of the intricate functions of NETs across the spectrum from physiology to pathology.

Interplay between host humoral pattern recognition molecules controls undue immune responses against Aspergillus fumigatus

Pentraxin 3 (PTX3), a long pentraxin and a humoral pattern recognition molecule (PRM), has been demonstrated to be protective against Aspergillus fumigatus, an airborne human fungal pathogen. We explored its mode of interaction with A. fumigatus, and the resulting implications in the host immune response. Here, we demonstrate that PTX3 interacts with A. fumigatus in a morphotype-dependent manner: (a) it recognizes germinating conidia through galactosaminogalactan, a surface exposed cell wall polysaccharide of A. fumigatus, (b) in dormant conidia, surface proteins serve as weak PTX3 ligands, and (c) surfactant protein D (SP-D) and the complement proteins C1q and C3b, the other humoral PRMs, enhance the interaction of PTX3 with dormant conidia. SP-D, C3b or C1q opsonized conidia stimulated human primary immune cells to release pro-inflammatory cytokines and chemokines. However, subsequent binding of PTX3 to SP-D, C1q or C3b opsonized conidia significantly decreased the production of pro-inflammatory cytokines/chemokines. PTX3 opsonized germinating conidia also significantly lowered the production of pro-inflammatory cytokines/chemokines while increasing IL-10 (an anti-inflammatory cytokine) released by immune cells when compared to the unopsonized counterpart. Overall, our study demonstrates that PTX3 recognizes A. fumigatus either directly or by interplaying with other humoral PRMs, thereby restraining detrimental inflammation. Moreover, PTX3 levels were significantly higher in the serum of patients with invasive pulmonary aspergillosis (IPA) and COVID-19-associated pulmonary aspergillosis (CAPA), supporting previous observations in IPA patients, and suggesting that it could be a potential panel-biomarker for these pathological conditions caused by A. fumigatus.

Prognostic Significance of Plasma Neutrophil Extracellular Trap Levels in Patients with Non-Small Cell Lung Cancer Treated with Immune Checkpoint Inhibitors

Neutrophil extracellular traps (NETs) released from neutrophils are related to cancer progression. However, the relationship between the therapeutic effects of immune checkpoint inhibitors (ICIs) such as anti-PD-1 and anti-PD-L1 antibodies and plasma NET concentration in patients with non-small cell lung cancer (NSCLC) is poorly understood. In this study, concentrations of citrullinated histone H3 (CitH3), a surrogate marker of NETs, in plasma before/after treatment were examined in patients with advanced or recurrent NSCLC undergoing ICI treatment (n = 185). The clinical significances of NET levels before/after treatment and posttreatment changes were statistically evaluated. As a result, multivariate Cox analysis showed that high NET levels before treatment were statistically significant predictors of unfavorable overall survival (OS; p < 0.001, HR 1.702, 95% CI 1.356-2.137) and progression-free survival (PFS; p < 0.001, HR 1.566, 95% CI 1.323-1.855). The Kaplan-Meier curves showed significant separation between the high- and low-NET groups in OS (p = 0.002) and PFS (p < 0.001). Additionally, high NET levels after treatment were also significantly associated with worse OS (p < 0.001) and PFS (p < 0.001) by multivariate Cox analysis. Notably, the pretreatment NET levels were significantly correlated with the plasma levels of NET-related inflammatory cytokines, such as IL-6 and IL-8, and with NET-related gene expression and immune-suppressive profile in peripheral blood mononuclear cells. Our findings suggest that NETs released from activated neutrophils might reduce the clinical efficacy of ICIs in patients with NSCLC.

Neutrophilic leukocytosis and erythema nodosum leprosum in leprosy: insights from a retrospective observational study

Background

Leprosy reactions represent immunologically mediated episodes of acute inflammation that, if not diagnosed and treated promptly, can cause irreversible impairment of nerve function and permanent disabilities. A frequent type of reaction experienced by patients with lepromatous leprosy (LL) and borderline lepromatous leprosy (BL) is erythema nodosum leprosum (ENL), an inflammatory complication that may become chronic or recur in multiple episodes. Although ENL is commonly described as a neutrophil-mediated immune disease, the role of neutrophils is not fully understood. In this study, we assess neutrophilic leukocytosis in a retrospective cohort of patients affected by BL or LL leprosy.

Materials and methods

A retrospective observational study was performed using data from 146 patients with BL and LL leprosy diagnosed and treated at the Souza Araújo Outpatient Clinic, Fiocruz, Rio de Janeiro, Brazil. Clinical, demographic, and hematological data were extracted from medical records. Skin biopsy samples obtained from patients for ENL diagnosis were used for histopathological evaluations.

Results

Most patients were male (75%) and had a reactional episode (85%), of which 65% were ENL. Multiple episodes were common, 55% of the 80 patients with ENL presented more than 2 episodes (average of 2.6 episodes). In treatment-naive BL/LL patients, the median blood neutrophil counts of patients who developed ENL at some points of their disease course were higher than those who did not experience any reaction (median= 4,567 cells/mm3 vs 3,731 cells/mm3 respectively, p=0.0286). A correlation between the increase in median neutrophil counts and ENL severity was confirmed (6,066 cells/mm3 for mild ENL vs 10,243 cells/mm3 for moderate/severe ENL, p=0.0009). A longitudinal assessment was also performed in 34 patients, confirming the neutrophilic leukocytosis (BL/LL: 4896 cells/mm3 vs ENL: 8408 cells/mm3, p<0.0001). Moreover, increased NLR was associated with a greater neutrophilic infiltration in ENL lesions.

Conclusion

We demonstrate that ENL episodes in patients affected by leprosy are associated with elevated blood leukocyte and neutrophil counts and an increased NLR. These findings highlight the significant involvement of neutrophils in the ENL immunological/inflammatory process.

The long Pentraxin PTX3 serves as an early predictive biomarker of co-infections in COVID-19

BACKGROUND

COVID-19 clinical course is highly variable and secondary infections contribute to COVID-19 complexity. Early detection of secondary infections is clinically relevant for patient outcome. Procalcitonin (PCT) and C-reactive protein (CRP) are the most used biomarkers of infections. Pentraxin 3 (PTX3) is an acute phase protein with promising performance as early biomarker in infections. In patients with COVID-19, PTX3 plasma concentrations at hospital admission are independent predictor of poor outcome. In this study, we assessed whether PTX3 contributes to early identification of co-infections during the course of COVID-19.

METHODS

We analyzed PTX3 levels in patients affected by COVID-19 with (n = 101) or without (n = 179) community or hospital-acquired fungal or bacterial secondary infections (CAIs or HAIs).

FINDINGS

PTX3 plasma concentrations at diagnosis of CAI or HAI were significantly higher than those in patients without secondary infections. Compared to PCT and CRP, the increase of PTX3 plasma levels was associated with the highest hazard ratio for CAIs and HAIs (aHR 11.68 and 24.90). In multivariable Cox regression analysis, PTX3 was also the most significant predictor of 28-days mortality or intensive care unit admission of patients with potential co-infections, faring more pronounced than CRP and PCT.

INTERPRETATION

PTX3 is a promising predictive biomarker for early identification and risk stratification of patients with COVID-19 and co-infections.

FUNDING

Dolce & Gabbana fashion house donation; Ministero della Salute for COVID-19; EU funding within the MUR PNRR Extended Partnership initiative on Emerging Infectious Diseases (Project no. PE00000007, INF-ACT) and MUR PNRR Italian network of excellence for advanced diagnosis (Project no. PNC-E3-2022-23683266 PNC-HLS-DA); EU MSCA (project CORVOS 860044).

Integrating genetic and immune factors to uncover pathogenetic mechanisms of viral-associated pulmonary aspergillosis

Invasive pulmonary aspergillosis is a severe fungal infection primarily affecting immunocompromised patients. Individuals with severe viral infections have recently been identified as vulnerable to developing invasive fungal infections. Both influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA) are linked to high mortality rates, emphasizing the urgent need for an improved understanding of disease pathogenesis to unveil new molecular targets with diagnostic and therapeutic potential. The recent establishment of animal models replicating the co-infection context has offered crucial insights into the mechanisms that underlie susceptibility to disease. However, the development and progression of human viral-fungal co-infections exhibit a significant degree of interindividual variability, even among patients with similar clinical conditions. This observation implies a significant role for host genetics, but information regarding the genetic basis for viral-fungal co-infections is currently limited. In this review, we discuss how genetic factors known to affect either antiviral or antifungal immunity could potentially reveal pathogenetic mechanisms that predispose to IAPA or CAPA and influence the overall disease course. These insights are anticipated to foster further research in both pre-clinical models and human patients, aiming to elucidate the complex pathophysiology of viral-associated pulmonary aspergillosis and contributing to the identification of new diagnostic and therapeutic targets to improve the management of these co-infections.

Humoral pathways of innate immune regulation in granuloma formation

The humoral arm of mammalian innate immunity regulates several molecular mechanisms involved in resistance to pathogens, inflammation, and tissue repair. Recent studies highlight the crucial role played by humoral mediators in granulomatous inflammation. However the molecular mechanisms linking the function of these soluble molecules to the initiation and maintenance of granulomas remain elusive. We propose that humoral innate immunity coordinates fundamental physiological processes in macrophages which, in turn, initiate activation and transformation events that enable granuloma formation. We discuss the involvement of humoral mediators in processes such as immune activation, phagocytosis, metabolism, and tissue remodeling, and how these can dictate macrophage functionality during granuloma formation. These advances present opportunities for discovering novel disease factors and developing targeted, more effective treatments for granulomatous diseases.

The Role of Neutrophils in Multiple Sclerosis and Ischemic Stroke

Inflammation plays an important role in numerous central nervous system (CNS) disorders. Its role is ambiguous-it can induce detrimental effects, as well as repair and recovery. In response to injury or infection, resident CNS cells secrete numerous factors that alter blood-brain barrier (BBB) function and recruit immune cells into the brain, like neutrophils. Their role in the pathophysiology of CNS diseases, like multiple sclerosis (MS) and stroke, is highly recognized. Neutrophils alter BBB permeability and attract other immune cells into the CNS. Previously, neutrophils were considered a homogenous population. Nowadays, it is known that various subtypes of these cells exist, which reveal proinflammatory or immunosuppressive functions. The primary goal of this review was to discuss the current knowledge regarding the important role of neutrophils in MS and stroke development and progression. As the pathogenesis of these two disorders is completely different, it gives the opportunity to get insight into diverse mechanisms of neutrophil involvement in brain pathology. Our understanding of the role of neutrophils in CNS diseases is still evolving as new aspects of their activity are being unraveled. Neutrophil plasticity adds another level to their functional complexity and their importance for CNS pathophysiology.

Chick heterophils release DNA extracellular traps (DETs) in vitro and in vivo upon Aspergillus fumigatus conidia exposure

Aspergillosis is a common fungal disease in avian species, causing high mortality in young chicks in agricultural farms and yards. It is caused by fungi belonging to the genus Aspergillus. Aspergillosis occurs by inhalation of fungal conidia, and in chickens, effective infection control relies on a rapid and large influx of heterophils to the lungs. Heterophils, upon different stimuli, release to the extracellular milieu their chromatin associated with several proteins that ensnare and kill different pathogens similarly to neutrophil extracellular traps. Here, we showed that Aspergillus fumigatus conidia and the peptidogalactomannan (PGM), isolated from the fungus cell wall, induce the release of DNA extracellular traps (DETs) in chicks' blood and lung heterophils. We demonstrated that reactive oxygen species, elastase and peptidyl arginine deiminase (PAD) were involved in DETs extrusion, the occurrence of DETs in the lungs of A. fumigatus-exposed chicks in vivo, and its role in chick survival. These results may contribute to developing more efficient tools for the therapeutic and diagnosis of aspergillosis.

From Mendel to mycoses: Immuno-genomic warfare at the human-fungus interface

Fungi are opportunists: They particularly require a defect of immunity to cause severe or disseminated disease. While often secondary to an apparent iatrogenic cause, fungal diseases do occur in the absence of one, albeit infrequently. These rare cases may be due to an underlying genetic immunodeficiency that can present variably in age of onset, severity, or other infections, and in the absence of a family history of disease. They may also be due to anti-cytokine autoantibodies. This review provides a background on how human genetics or autoantibodies underlie cases of susceptibility to severe or disseminated fungal disease. Subsequently, the lessons learned from these inborn errors of immunity marked by fungal disease (IEI-FD) provide a framework to begin to mechanistically decipher fungal syndromes, potentially paving the way for precision therapy of the mycoses.

The role of predictive and prognostic values of inflammatory markers in acute pancreatitis: a narrative review

Pancreatitis is an inflammatory condition affecting the pancreas and is classified into 2 types, acute and chronic, which can manifest in various forms. This review article summarizes the role of predictive and prognostic values of inflammatory markers in the pathogenesis of acute pancreatitis, mainly focused on preclinical and clinical studies. It includes serum amyloid A (SAA), monocyte chemotactic protein-1 (MCP-1), erythrocyte sedimentation rate (ESR), interleukin-6 (IL-6), C-reactive protein (CRP), IL-10, myeloperoxidase, pentraxin 3, and plasminogen activator inhibitor 1. SAA3 plays a crucial role in developing acute pancreatitis by triggering a receptor-interacting protein 3–dependent necroptosis pathway in acinar cells. Targeting SAA3 could be a potential strategy for treating acute pancreatitis. The recruitment of monocytes/macrophages and the activation of the systemic MCP-1 signaling pathway play a role in the progression of pancreatitis, and blocking MCP-1 may have a suppressive effect on the development of pancreatic fibrosis. The ESR can predict severe acute pancreatitis with slightly lower accuracy than CRP. When ESR and CRP levels are combined at 24 hours, they predict severe acute pancreatitis accurately. IL-6 plays a crucial role in activating the Janus kinase/signal transducers and activators of the transcription pathway, exacerbating pancreatitis and contributing to the initiation and progression of pancreatic cancer. Endogenous IL-10 plays a crucial role in controlling the regenerative phase and limiting the severity of fibrosis and glandular atrophy induced by repeated episodes of acute pancreatitis in mice. The predictive and diagnostic roles of these inflammatory factors in pancreatitis were introduced in detail in this review.

Complement-pentraxins synergy: Navigating the immune battlefield and beyond

The complement is a crucial immune defense system that triggers rapid immune responses and offers efficient protection against foreign invaders and unwanted host elements, acting as a sentinel. Activation of the complement system occurs upon the recognition of pathogenic microorganisms or altered self-cells by pattern-recognition molecules (PRMs) such as C1q, collectins, ficolins, and pentraxins. Recent accumulating evidence shows that pentraxins establish a cooperative network with different classes of effector PRMs, resulting in synergistic effects in complement activation. This review describes the complex interaction of pentraxins with the complement system and the implications of this cooperative network for effective host defense during pathogen invasion.

Animal protein intake is directly associated with serum level of pentraxin 3 in hemodialysis patients

Inflammation plays an important role in Cardiovascular disease (CVD) pathogenesis as the main cause of mortality in hemodialysis (HD) patients. Despite the relevance of nutrition and dietary intakes for inflammation status, the role of dietary protein sources remains unclear. The aim of this study was to evaluate the association between the different types of dietary protein and pentraxin 3 (PTX3) levels in HD patients. In this multi-center cross-sectional study, 227 adult patients undergoing HD for a minimum 90 days were recruited. A validated 168-item food frequency questionnaire was used to assess dietary intakes. Also, 5 ml blood samples were collected from each patient to measure the concentration of serum PTX3. Overall, 227 patients, including 63 women and 164 men, with a mean age of 58 years, participated in this study. There was a greater intake of animal protein per kilogram dry weight among patients with higher levels of PTX3 (0.46 vs. 0.54 g/kg; P = 0.035). In contrast, consumption of total protein and plant protein per kilogram dry weight was not different across PTX3 levels. Moreover, the chance of increased PTX3 concentration was directly associated with a one-unit increase in animal protein intake per kilogram dry weight, after adjusting for confounders. We did not observe any association between one-unit increases in plant protein intake per kilogram dry weight and chance of increased PTX3. In conclusion, animal protein intake was directly associated with circulating PTX3.

Crosstalk between neutrophil extracellular traps and immune regulation: insights into pathobiology and therapeutic implications of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated death, occurring during or within 6 hours after transfusion. Reports indicate that TRALI can be categorized as having or lacking acute respiratory distress syndrome (ARDS) risk factors. There are two types of TRALI in terms of its pathogenesis: antibody-mediated and non-antibody-mediated. The key initiation steps involve the priming and activation of neutrophils, with neutrophil extracellular traps (NETs) being established as effector molecules formed by activated neutrophils in response to various stimuli. These NETs contribute to the production and release of reactive oxygen species (ROS) and participate in the destruction of pulmonary vascular endothelial cells. The significant role of NETs in TRALI is well recognized, offering a potential pathway for TRALI treatment. Moreover, platelets, macrophages, endothelial cells, and complements have been identified as promoters of NET formation. Concurrently, studies have demonstrated that the storage of platelets and concentrated red blood cells (RBC) can induce TRALI through bioactive lipids. In this article, recent clinical and pre-clinical studies on the pathophysiology and pathogenesis of TRALI are reviewed to further illuminate the mechanism through which NETs induce TRALI. This review aims to propose new therapeutic strategies for TRALI, with the hope of effectively improving its poor prognosis.

Role of long pentraxin PTX3 in cancer

Cancer has become a leading cause of death and disease burden worldwide, closely related to rapid socioeconomic development. However, the fundamental reason is the lack of comprehensive understanding of the mechanism of cancer, accurate identification of preclinical cancer, and effective treatment of the disease. Therefore, it is particularly urgent to study specific mechanisms of cancer and develop effective prediction and treatment methods. Long Pentraxin PTX3 is a soluble pattern recognition molecule produced by various cells in inflammatory sites, which plays a role as a promoter or suppressor of cancer in multiple tumors through participating in innate immune response, neovascularization, energy metabolism, invasion, and metastasis mechanisms. Based on this, this article mainly reviews the role of PTX3 in various cancers.

Pentraxins in invertebrates and vertebrates: From structure, function and evolution to clinical applications

The immune system is divided into two broad categories, consisting of innate and adaptive immunity. As recognition and effector factors of innate immunity and regulators of adaptive immune responses, lectins are considered to be important defense chemicals against microbial pathogens, cell trafficking, immune regulation, and prevention of autoimmunity. Pentraxins, important members of animal lectins, play a significant role in protecting the body from pathogen infection and regulating inflammatory reactions. They can recognize and bind to a variety of ligands, including carbohydrates, lipids, proteins, nucleic acids and their complexes, and protect the host from pathogen invasion by activating the complement cascade and Fcγ receptor pathways. Based on the primary structure of the subunit, pentraxins are divided into short and long pentraxins. The short pentraxins are comprised of C-reactive protein (CRP) and serum amyloid P (SAP), and the most important member of the long pentraxins is pentraxin 3 (PTX3). The CRP and SAP exist in both vertebrates and invertebrates, while the PTX3 may be present only in vertebrates. The major ligands and functions of CRP, SAP and PTX3 and three activation pathways involved in the complement system are summarized in this review. Their different characteristics in various animals including humans, and their evolutionary trees are analyzed. The clinical applications of CRP, SAP and PTX3 in human are reviewed. Some questions that remain to be understood are also highlighted.

Long-chain pentraxin 3 possesses agglutination activity and plays a role in host defense against bacterial infection in Oreochromis niloticus

Pentraxin 3 (PTX3) is a soluble pattern recognition molecule in the innate immune system that has multiple functions. It is involved in resisting pathogen infection. However, the functions of PTX3 in teleost fish are not well understood. In this study, we identified and characterized PTX3 in Nile tilapia (Oreochromis niloticus) (OnPTX3). The open reading frame of OnPTX3 was found to be 1305 bp, encoding 434 aa. We conducted spatial mRNA expression analysis and found that the expression of OnPTX3 was significantly increased after infection with Streptococcus agalactiae and Aeromonas hydrophila, both in vivo and in vitro. We also observed that recombinant OnPTX3 protein could bind and agglutinate bacterial pathogen. Furthermore, OnPTX3 enhanced the phagocytosis of bacteria (S. agalactiae and A. hydrophila) by head kidney macrophages. Additionally, OnPTX3 was found to influence the expression of inflammatory cytokines, suggesting its involvement in the regulation of the inflammatory response. Moreover, OnPTX3 was shown to promote complement-mediated hemolysis and possess antibacterial activity. In conclusion, our research demonstrates that OnPTX3 has bacterial binding and agglutination activities, enhances phagocytosis, and regulates inflammation. It plays a crucial role in the defense of Nile tilapia against pathogenic bacteria, providing valuable insights for the prevention and control of aquatic diseases in the future.

The pentraxin family in autoimmune disease

The pentraxins represent a family of multifunctional proteins composed of long and short pentamers. The latter includes serum amyloid P component (SAP) and C-reactive protein (CRP) whereas the former includes neuronal PTX1 and PTX2 (NPTX1 and NPTX2, respectively), PTX3 and PTX4. These serve as a bridge between adaptive immunity and innate immunity and a link between inflammation and immunity. Similarities and differences between long and short pentamers are examined and their roles in autoimmune disease are discussed. Increased CRP and PTX3 could indicate the activity of rheumatoid arthritis, systemic lupus erythematosus or other autoimmune diseases. Mechanistically, CRP and PTX3 may predict target organ injury, regulate bone metabolic immunity and maintain homeostasis as well as participate in vascular endothelial remodeling. Interestingly, PTX3 is pleiotropic, being involved in inflammation and tissue repair. Given the therapeutic potential of PTX3 and CRP, targeting these factors to exert a beneficial effect is the focus of research efforts. Unfortunately, studies on NPTX1, NPTX2, PTX4 and SAP are scarce and more research is clearly needed to elaborate their potential roles in autoimmune disease.

Hantavirus: an overview and advancements in therapeutic approaches for infection

Hantaviruses are a significant and emerging global public health threat, impacting more than 200,000 individuals worldwide each year. The single-stranded RNA viruses belong to the Hantaviridae family and are responsible for causing two acute febrile diseases in humans: Hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS). Currently, there are no licensed treatments or vaccines available globally for HTNV infection. Various candidate drugs have shown efficacy in increasing survival rates during the early stages of HTNV infection. Some of these drugs include lactoferrin, ribavirin, ETAR, favipiravir and vandetanib. Immunotherapy utilizing neutralizing antibodies (NAbs) generated from Hantavirus convalescent patients show efficacy against HTNV. Monoclonal antibodies such as MIB22 and JL16 have demonstrated effectiveness in protecting against HTNV infection. The development of vaccines and antivirals, used independently and/or in combination, is critical for elucidating hantaviral infections and the impact on public health. RNA interference (RNAi) arised as an emerging antiviral therapy, is a highly specific degrades RNA, with post-transcriptional mechanism using eukaryotic cells platform. That has demonstrated efficacy against a wide range of viruses, both in vitro and in vivo. Recent antiviral methods involve using small interfering RNA (siRNA) and other, immune-based therapies to target specific gene segments (S, M, or L) of the Hantavirus. This therapeutic approach enhances viral RNA clearance through the RNA interference process in Vero E6 cells or human lung microvascular endothelial cells. However, the use of siRNAs faces challenges due to their low biological stability and limited in vivo targeting ability. Despite their successful inhibition of Hantavirus replication in host cells, their antiviral efficacy may be hindered. In the current review, we focus on advances in therapeutic strategies, as antiviral medications, immune-based therapies and vaccine candidates aimed at enhancing the body's ability to control the progression of Hantavirus infections, with the potential to reduce the risk of severe disease.

The Diagnostic and Assessment Value of Plasma Pentraxin 3 in Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

Pentraxin 3 (PTX3) is an acute-phase protein and an important inflammatory mediator. We hypothesized plasma PTX3 could be a valuable diagnostic biomarker in acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Methods

In this prospective controlled study, 458 COPD patients and 71 healthy controls from May 2019 to December 2020 in two hospitals were enrolled. COPD patients were divided into AECOPD group (n = 173) and stable COPD group (n = 285). AECOPD patients were subdivided into mild or moderate group (n = 43) and severe group (n = 130) based on severity. Plasma PTX3 levels were detected by ELISA.

Results

Plasma PTX3 levels were significantly higher in AECOPD (2.8 ng/mL) compared to stable COPD (0.87 ng/mL) and healthy controls (0.83 ng/mL). In the analysis of AECOPD subgroups, plasma PTX3 level of severe group (4.51 ng/mL) was significantly higher than that of mild or moderate group (1.25 ng/mL). Patients with respiratory failure had higher PTX3 than those without respiratory failure. No difference was observed between stable COPD patients and healthy controls. ROC analysis showed that plasma PTX3 had a considerable ability to distinguish AECOPD from stable COPD [AUC: 0.85, 95% CI (0.81-0.88), P < 0.0001; cut-off 1.25 ng/mL, sensitivity 77.5%, specificity 74%]. AUC of PTX3 was better than CRP regarding diagnosis of AECOPD. Combination of PTX3 and CRP was superior to either of them in diagnosing AECOPD.

Conclusion

Plasma PTX3 levels were significantly higher in AECOPD than stable COPD. The level was associated with the severity of exacerbation. Plasma PTX3 has potential value as a biomarker to diagnose and evaluate AECOPD.

Mechanisms of Neutrophil Extracellular Trap Formation and Regulation in Cancers

As one of the most important components of the innate immune system, neutrophils are always at the forefront of the response to diseases. The immune functions of neutrophils include phagocytosis, degranulation, production of reactive oxygen species, and the production of neutrophil extracellular traps (NETs). NETs are composed of deconcentrated chromatin DNA, histones, myeloperoxidase (MPO) and neutrophil elastase (NE), playing an important role in the resistance to some pathogenic microbial invasions. Until recent years, when NETs were found to play a critical role in cancer. NETs play bidirectional regulation both positive and negative roles in the development and progression of cancer. Targeted NETs may provide new therapeutic strategies for the treatment of cancer. However, the molecular and cellular regulatory mechanisms underlying the formation and role of NET in cancer remain unclear. This review just summarizes the recent progress in regulatory mechanisms about the formation of NETs and their role in cancers.

Neutrophil diversity in inflammation and cancer

Neutrophils are the most abundant circulating leukocytes in humans and the first immune cells recruited at the site of inflammation. Classically perceived as short-lived effector cells with limited plasticity and diversity, neutrophils are now recognized as highly heterogenous immune cells, which can adapt to various environmental cues. In addition to playing a central role in the host defence, neutrophils are involved in pathological contexts such as inflammatory diseases and cancer. The prevalence of neutrophils in these conditions is usually associated with detrimental inflammatory responses and poor clinical outcomes. However, a beneficial role for neutrophils is emerging in several pathological contexts, including in cancer. Here we will review the current knowledge of neutrophil biology and heterogeneity in steady state and during inflammation, with a focus on the opposing roles of neutrophils in different pathological contexts.

IL-4, IL-13 and IFN-γ -induced genes in highly purified human neutrophils

Interleukin (IL)-4 and IL-13 are related cytokines with well-known specific roles in type 2 immune response. However, their effects on neutrophils are not completely understood. For this, we studied human primary neutrophil responses to IL-4 and IL-13. Neutrophils are dose-dependently responsive to both IL-4 and IL-13 as indicated by signal transducer and activator of transcription 6 (STAT6) phosphorylation upon stimulation, with IL-4 being more potent inducer of STAT6. IL-4-, IL-13- and Interferon (IFN)-γ-stimulated gene expression in highly purified human neutrophils induced both overlapping and unique gene expression in highly purified human neutrophils. IL-4 and IL-13 specifically regulate several immune-related genes, including IL-10, tumor necrosis factor (TNF) and leukemia inhibitory factor (LIF), while type1 immune response-related IFN-γ induced gene expression related for example, to intracellular infections. In analysis of neutrophil metabolic responses, oxygen independent glycolysis was specifically regulated by IL-4, but not by IL-13 or IFN-γ, suggesting specific role for type I IL-4 receptor in this process. Our results provide a comprehensive analysis of IL-4, IL-13 and IFN-γ -induced gene expression in neutrophils while also addressing cytokine-mediated metabolic changes in neutrophils.

CAFs orchestrates tumor immune microenvironment—A new target in cancer therapy?

Cancer immunotherapy has opened a new landscape in cancer treatment, however, the poor specificity and resistance of most targeted therapeutics have limited their therapeutic efficacy. In recent years, the role of CAFs in immune regulation has been increasingly noted as more evidence has been uncovered regarding the link between cancer-associated fibroblasts (CAFs) and the evolutionary process of tumor progression. CAFs interact with immune cells to shape the tumor immune microenvironment (TIME) that favors malignant tumor progression, a crosstalk process that leads to the failure of cancer immunotherapies. In this review, we outline recent advances in the immunosuppressive function of CAFs, highlight the mechanisms of CAFs-immune cell interactions, and discuss current CAF-targeted therapeutic strategies for future study.

NETworking with cancer: The bidirectional interplay between cancer and neutrophil extracellular traps

Neutrophils are major effectors and regulators of the immune system. They play critical roles not only in the eradication of pathogens but also in cancer initiation and progression. Conversely, the presence of cancer affects neutrophil activity, maturation, and lifespan. By promoting or repressing key neutrophil functions, cancer cells co-opt neutrophil biology to their advantage. This co-opting includes hijacking one of neutrophils' most striking pathogen defense mechanisms: the formation of neutrophil extracellular traps (NETs). NETs are web-like filamentous extracellular structures of DNA, histones, and cytotoxic granule-derived proteins. Here, we discuss the bidirectional interplay by which cancer stimulates NET formation, and NETs in turn support disease progression. We review how vascular dysfunction and thrombosis caused by neutrophils and NETs underlie an elevated risk of death from cardiovascular events in cancer patients. Finally, we propose therapeutic strategies that may be effective in targeting NETs in the clinical setting.

Virus-associated fungal infections and lost immune resistance

Invasive fungal infections are an increasing threat to human health. Of recent concern is the emergence of influenza- or SARS-CoV-2-virus-associated invasive fungal infections. Understanding acquired susceptibilities to fungi requires consideration of the collective and newly explored roles of adaptive, innate, and natural immunity. Neutrophils are known to provide host resistance, but new concepts are emerging that implicate innate antibodies, the actions of specialized B1 B cell subsets, and B cell-neutrophil crosstalk in mediating antifungal host resistance. Based on emerging evidence, we propose that virus infections impact on neutrophil and innate B cell resistance against fungi, leading to invasive infections. These concepts provide novel approaches to developing candidate therapeutics with the aim of restoring natural and humoral immunity and boosting neutrophil resistance against fungi.

Pentraxin 3 in the cerebrospinal fluid during central nervous system infections: A retrospective cohort study

The present study describes diagnostic and prognostic abilities of Cerebrospinal fluid (CSF) Pentraxin 3 (PTX3) in central nervous system (CNS) infections. CSF PTX3 was measured retrospectively from 174 patients admitted under suspicion of CNS infection. Medians, ROC curves and Youdens index was calculated. CSF PTX3 was significantly higher among all CNS infections and undetectable in most of the patients in the control group, and significantly higher in bacterial infections compared to viral and Lyme infections. No association was found between CSF PTX3 and Glasgow Outcome Score. PTX3 in the CSF can distinguish bacterial infection from viral and Lyme infections and non-CNS infections. Highest levels were found in bacterial meningitis. No prognostic abilities were found.

Long Pentraxin 3 as a New Biomarker for Diagnosis of Hip and Knee Periprosthetic Joint Infections

BACKGROUND

Preoperative diagnosis of periprosthetic joint infections (PJIs) poses an unmet clinical challenge. The long pentraxin PTX3 is a component of the innate immune system involved in infection immunity. This study evaluated the potential of synovial and plasmatic PTX3 in the diagnosis of hip and knee PJIs.

METHODS

Consecutive total hip and knee arthroplasty (THA/TKA) revisions were prospectively included and classified as septic or aseptic according to the European Bone and Joint Infection Society (EBJIS) and Musculoskeletal Infection Society (MSIS) criteria. The concentration of PTX3 in plasma and synovial fluid samples was measured with ELISA. The AUC, threshold value, sensitivity, specificity, and positive and negative likelihood ratios were calculated using the ROC (receiver operating characteristic) curve method.

RESULTS

The study population included 128 patients (94 THAs; 34 TKAs). The AUC of the synovial PTX3 based on EBJIS criteria was 0.85 (p < 0.0001), with a sensitivity of 81.13% and a specificity of 93.33%. The AUC based on MSIS criteria was 0.95 (p < 0.001), with a sensitivity of 91.43% and a specificity of 89.25%. Plasmatic PTX3 failed to discriminate infected from non-infected patients.

CONCLUSIONS

Synovial PTX3 demonstrated an excellent diagnostic potential in hip and knee PJIs, with a very high specificity irrespective of the diagnostic criteria for PJI.

Distinct subsets of neutrophils crosstalk with cytokines and metabolites in patients with sepsis

Sepsis is a life-threatening condition caused by a dysregulated host response to infection. Despite continued efforts to understand the pathophysiology of sepsis, no effective therapies are currently available. While singular components of the aberrant immune response have been investigated, comprehensive studies linking different data layers are lacking. Using an integrated systems immunology approach, we evaluated neutrophil phenotypes and concomitant changes in cytokines and metabolites in patients with sepsis. Our findings identify differentially expressed mature and immature neutrophil subsets in patients with sepsis. These subsets correlate with various proteins, metabolites, and lipids, including pentraxin-3, angiopoietin-2, and lysophosphatidylcholines, in patients with sepsis. These results enabled the construction of a statistical model based on weighted multi-omics linear regression analysis for sepsis biomarker identification. These findings could help inform early patient stratification and treatment options, and facilitate further mechanistic studies targeting the trifecta of surface marker expression, cytokines, and metabolites.

Expression of pentraxin 3 in equine lungs and neutrophils

Endotoxin-induced diseases cause significant mortality and morbidity in the horse, leading to enormous economic damage to the equine industry. Neutrophils play a critical role in initiating the immune response in the lung. Pattern recognition receptors (PRRs) are programmed to recognize microbial structures unique to pathogens and mount an immune response. Pentraxin 3 (PTX3) is a PRR that is produced at sites of inflammation by many cell types upon stimulation by pro-inflammatory cytokines and agonists, such as endotoxins [also known as lipopolysaccharides (LPS)]. Pentraxin 3 recognizes and binds to many pathogens, activates the complement cascade, and has a role in the clearance of apoptotic and necrotic cells. Recently, PTX3 has been reported to be localized in the specific granules in human and mouse neutrophils, but no reports exist on the in-situ localization of PTX3 in neutrophils and the lungs of horses. Therefore, the objective of this study was to localize the PTX3 protein in normal and LPS-exposed neutrophils and in normal equine lungs. Immunohistochemical data showed PTX3 staining in the bronchial epithelial cells and the vascular endothelium of normal lungs. Immunogold electron microscopy localized PTX3 in the nuclei, cytoplasm, and vesicular organelles of alveolar macrophages, endothelial cells, and pulmonary intravascular macrophages. Immunohistochemical staining for PTX3 in isolated horse neutrophils showed an altered staining pattern in neutrophils stimulated with LPS. These data suggest that neutrophils may be a mobile form of PTX3 that is readily shuttled to the site of inflammation, where it can be released to fine tune a host defense response.

The crossroad between autoimmune disorder, tissue remodeling and cancer of the thyroid: The long pentraxin 3 (PTX3)

Thyroid is at the crossroads of immune dysregulation, tissue remodeling and oncogenesis. Autoimmune disorders, nodular disease and cancer of the thyroid affect a large amount of general population, mainly women. We wondered if there could be a common factor behind three processes (immune dysregulation, tissue remodeling and oncogenesis) that frequently affect, sometimes coexisting, the thyroid gland. The long pentraxin 3 (PTX3) is an essential component of the humoral arm of the innate immune system acting as soluble pattern recognition molecule. The protein is found expressed in a variety of cell types during tissue injury and stress. In addition, PTX3 is produced by neutrophils during maturation in the bone-marrow and is stored in lactoferrin-granules. PTX3 is a regulator of the complement cascade and orchestrates tissue remodeling and repair. Preclinical data and studies in human tumors indicate that PTX3 can act both as an extrinsic oncosuppressor by modulating complement-dependent tumor-promoting inflammation, or as a tumor-promoter molecule, regulating cell invasion and proliferation and epithelial to mesenchymal transition, thus suggesting that this molecule may have different functions on carcinogenesis. The involvement of PTX3 in the regulation of immune responses, tissue remodeling and oncosuppressive processes led us to explore its potential role in the development of thyroid disorders. In this review, we aimed to highlight what is known, at the state of the art, regarding the connection between the long pentraxin 3 and the main thyroid diseases i.e., nodular thyroid disease, thyroid cancer and autoimmune thyroid disorders.

Emerging Role of Neutrophil Extracellular Traps in Gastrointestinal Tumors: A Narrative Review

Neutrophil extracellular traps (NETs) are extracellular fibrous networks consisting of depolymerized chromatin DNA skeletons with a variety of antimicrobial proteins. They are secreted by activated neutrophils and play key roles in host defense and immune responses. Gastrointestinal (GI) malignancies are globally known for their high mortality and morbidity. Increasing research suggests that NETs contribute to the progression and metastasis of digestive tract tumors, among them gastric, colon, liver, and pancreatic cancers. This article explores the formation of NETs and reviews the role that NETs play in the gastrointestinal oncologic microenvironment, tumor proliferation and metastasis, tumor-related thrombosis, and surgical stress. At the same time, we analyze the qualitative and quantitative detection methods of NETs in recent years and found that NETs are specific markers of coronavirus disease 2019 (COVID-19). Then, we explore the possibility of NET inhibitors for the treatment of digestive tract tumor diseases to provide a new, efficient, and safe solution for the future therapy of gastrointestinal tumors.

Basophils from allergy to cancer

Human basophils, first identified over 140 years ago, account for just 0.5-1% of circulating leukocytes. While this scarcity long hampered basophil studies, innovations during the past 30 years, beginning with their isolation and more recently in the development of mouse models, have markedly advanced our understanding of these cells. Although dissimilarities between human and mouse basophils persist, the overall findings highlight the growing importance of these cells in health and disease. Indeed, studies continue to support basophils as key participants in IgE-mediated reactions, where they infiltrate inflammatory lesions, release pro-inflammatory mediators (histamine, leukotriene C₄: LTC₄) and regulatory cytokines (IL-4, IL-13) central to the pathogenesis of allergic diseases. Studies now report basophils infiltrating various human cancers where they play diverse roles, either promoting or hampering tumorigenesis. Likewise, this activity bears remarkable similarity to the mounting evidence that basophils facilitate wound healing. In fact, both activities appear linked to the capacity of basophils to secrete IL-4/IL-13, with these cytokines polarizing macrophages toward the M2 phenotype. Basophils also secrete several angiogenic factors (vascular endothelial growth factor: VEGF-A, amphiregulin) consistent with these activities. In this review, we feature these newfound properties with the goal of unraveling the increasing importance of basophils in these diverse pathobiological processes.

Pentraxin 3 Facilitates Shrimp-Allergic Responses in IgE-Activated Mast Cells

BACKGROUND

Since food avoidance is currently the only way to prevent allergic reactions to shrimp, a better understanding of molecular events in the induction and progression of allergy, including food allergy, is needed for developing strategies to inhibit allergic responses. Pentraxin 3 (PTX3) is rapidly produced directly from inflammatory or damaged tissues and is involved in acute immunoinflammatory responses. However, the role of PTX3 in the development of immediate IgE-mediated shrimp allergy remains unknown.

METHODS

Wild-type BALB/c mice were immunized intraperitoneally and were challenged with shrimp extract. Serum IgE and PTX3 levels were analyzed. RBL-2H3 cells were stimulated with either dinitrophenyl (DNP) or serum of shrimp-allergic mice, and markers of degranulation, proinflammatory mediators, and phosphorylation of signal proteins were analyzed. We further examined the effect of PTX3 in shrimp extract-induced allergic responses in vitro and in vivo.

RESULTS

Mice with shrimp allergy had increased PTX3 levels in the serum and small intestine compared with healthy mice. PTX3 augmented degranulation, the production of proinflammatory mediators, and activation of the Akt and MAPK signaling pathways in mast cells upon DNP stimulation. Furthermore, the expression of transcription factor CCAAT/enhancer-binding protein delta (CEBPD) was elevated in PTX3-mediated mast cell activation. Finally, the PTX3 inhibitor RI37 could attenuate PTX3-induced degranulation, proinflammatory mediator expression, and phosphorylation of the Akt and MAPK signaling.

CONCLUSIONS

The results suggested that PTX3 can facilitate allergic responses. Our data provide new insight to demonstrate that PTX3 is a cause of allergic inflammation and that RI37 can serve as a therapeutic agent in shrimp allergy.

Molecular insight into pentraxin-3: Update advances in innate immunity, inflammation, tissue remodeling, diseases, and drug role

Pentraxin-3 (PTX3) is the prototype of the long pentraxin subfamily, an acute-phase protein consisting of a C-terminal pentraxin domain and a unique N-terminal domain. PTX3 was initially isolated from human umbilical vein endothelial cells and human FS-4 fibroblasts. It was subsequently found to be also produced by synoviocytes, chondrocytes, osteoblasts, smooth muscle cells, myeloid dendritic cells, epithelial cells, and tumor cells. Various modulatory factors, such as miRNAs, cytokines, drugs, and hypoxic conditions, could regulate the expression level of PTX3. PTX3 is essential in regulating innate immunity, inflammation, angiogenesis, and tissue remodeling. Besides, PTX3 may play dual (pro-tumor and anti-tumor) roles in oncogenesis. PTX3 is involved in the occurrence and development of many non-cancerous diseases, including COVID-19, and might be a potential biomarker indicating the prognosis, activity,and severity of diseases. In this review, we summarize and discuss the potential roles of PTX3 in the oncogenesis and pathogenesis of non-cancerous diseases and potential targeted therapies based on PTX3.

Pentraxin 3 in Circulating Microvesicles: a Potential Biomarker for Acute Heart Failure After Cardiac Surgery with Cardiopulmonary Bypass

The aim of this study was to investigate whether pentraxin 3 (PTX3) in microvesicles (MVs) can be a valuable biomarker for the prediction of acute heart failure (AHF) after cardiac surgery with cardiopulmonary bypass (CPB). One hundred and twenty-four patients undergoing cardiac surgery with CPB were included and analyzed (29 with AHF and 95 without AHF). The concentrations of PTX3 in MVs isolated from plasma were measured by ELISA kits before, 12 h, and 3 days after surgery. Patients' demographics, medical history, surgical data, and laboratory results were collected. The levels of PTX3 in MVs were significantly elevated during perioperative surgery, which was increased more in the AHF group. The concentrations of PTX3 in MVs at postoperative 12 h were independent risk factors for AHF with the area under the ROC curve of 0.920. The concentration of PTX3 in MVs may be a novel biomarker for prediction of AHF after cardiac surgery.