Pentraxin 3: an immuno-regulator in the lungs

RNA m6A methylation modulates airway inflammation in allergic asthma via PTX3-dependent macrophage homeostasis

N6-methyladenosine (m6A), the most prevalent mRNA modification, has an important function in diverse biological processes. However, the involvement of m6A in allergic asthma and macrophage homeostasis remains largely unknown. Here we show that m6A methyltransferases METTL3 is expressed at a low level in monocyte-derived macrophages from childhood allergic asthma patients. Conditional knockout of Mettl3 in myeloid cells enhances Th2 cell response and aggravates allergic airway inflammation by facilitating M2 macrophage activation. Loss and gain functional studies confirm that METTL3 suppresses M2 macrophage activation partly through PI3K/AKT and JAK/STAT6 signaling. Mechanistically, m6A-sequencing shows that loss of METTL3 impairs the m6A-YTHDF3-dependent degradation of PTX3 mRNA, while higher PTX3 expression positively correlates with asthma severity through promoting M2 macrophage activation. Furthermore, the METTL3/YTHDF3-m6A/PTX3 interactions contribute to autophagy maturation in macrophages by modulating STX17 expression. Collectively, this study highlights the function of m6A in regulating macrophage homeostasis and identifies potential targets in controlling allergic asthma.

PTX3 shapes profibrotic immune cells and epithelial/fibroblast repair and regeneration in a murine model of pulmonary fibrosis

The long pentraxin 3 (PTX3) is protective in different pathologies but was not analyzed in-depth in Idiopathic Pulmonary Fibrosis (IPF). Here, we have explored the influence of PTX3 in the bleomycin (BLM)-induced murine model of IPF by looking at immune cells (macrophages, mast cells, T cells) and stemness/regenerative markers of lung epithelium (SOX2) and fibro-blasts/myofibroblasts (CD44) at different time points that retrace the progression of the disease from onset at day 14, to full-blown disease at day 21, to incomplete regression at day 28. We took advantage of transgenic PTX3 overexpressing mice (Tie2-PTX3) and Ptx3 null ones (PTX3-KO) in which pulmonary fibrosis was induced. Our data have shown that PTX3 overexpression in Tie2-PTX3 compared to WT or PTX3-KO: reduced CD68+ and CD163+ macrophages and the Tryptase+ mast cells during the whole experimental time; on the contrary, CD4+ T cells are consistently present on day 14 and dramatically decreased on day 21; CD8+ T cells do not show significant differences on day 14, but are significantly reduced on day 21; SOX2 is reduced on days 14 and 21; CD44 is reduced on day 21. Therefore, PTX3 could act on the proimmune and fibrogenic microenvironment to prevent fibrosis in BLM-treated mice.

Increased Levels of serum Pentraxin 3 in Critical Coronavirus Disease-2019 Patients

Pentraxin 3 (PTX3) and ficolin are the plasma phase of pattern recognition receptors (PRRs) and can activate complement through classical and lectin pathways, respectively, which may contribute to disease severity. This study aimed to investigate the association between PTX3 and ficolin with disease severity in patients with coronavirus disease-2019 (COVID-19). Seventy-three COVID-19 patients and 25 healthy controls were enrolled in this study. The participants were divided into three groups as follows: 14 patients as the intensive care unit (ICU) group, 59 patients as the non-ICU group, and 25 subjects as the healthy control group. The serum levels of PTX3 and ficolin were measured by enzyme-linked immunosorbent assay (ELISA) kits. Patients in ICU and non-ICU groups had significantly higher levels of PTX3 compared to the healthy control group (p = 0.0002 and p = 0.0072, respectively). Patients in the ICU group also had an increased amount of PTX3 (1957 ± 1769 pg/ml) compared to non-ICU patients (1220 ± 1784 pg/ml). However, this difference was not significant. On the other hand, serum levels of ficolin were not different among the three groups. PTX3, as an acute phase protein, may contribute to disease severity. Its probable inflammatory role could result from the high activation of the complement system. On the other hand, it could be suggested that ficolin has no crucial role in the disease severity of COVID-19 patients.

RETRACTED: The pathogenicity of COVID-19 and the role of pentraxin-3: An updated review study

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. In investigating concerns regarding the contributions of the authors to this article, the editors reached out to the authors for an explanation. In addition to the concerns regarding the contribution of each author, the editors discovered suspicious changes in authorship between the original submission and the revised version of this paper. The names of the authors Ameer A Alameri and Zanko Hassan Jawhar were added to the revised version of the article without explanation and without the exceptional approval by the handling Editor, which is contrary to the journal policy on changes to authorship. The authors were unable to provide a reasonable explanation for either of the issues raised. The editor therefore feels that the findings of the manuscript cannot be relied upon and that the article needs to be retracted.

The Lung Microbiota Affects Pulmonary Inflammation and Oxidative Stress Induced by PM2.5 Exposure

Fine particulate matter (PM_2.5) exposure causes respiratory diseases by inducing inflammation and oxidative stress. However, the correlation between the pulmonary microbiota and the progression of pulmonary inflammation and oxidative stress caused by PM_2.5 is poorly understood. This study tested the hypothesis that the lung microbiota affects pulmonary inflammation and oxidative stress induced by PM_2.5 exposure. Mice were exposed to PM_2.5 intranasally for 12 days. Then, pulmonary microbiota transfer and antibiotic intervention were performed. Histological examinations, biomarker index detection, and transcriptome analyses were conducted. Characterization of the pulmonary microbiota using 16S rRNA gene sequencing showed that its diversity decreased by 75.2% in PM_2.5-exposed mice, with increased abundance of Proteobacteria and decreased abundance of Bacteroidota. The altered composition of the microbiota was significantly correlated with pulmonary inflammation and oxidative stress-related indicators. Intranasal transfer of the pulmonary microbiota from PM_2.5-exposed mice affected pulmonary inflammation and oxidative stress caused by PM_2.5, as shown by increased proinflammatory cytokine levels and dysregulated oxidative damage-related biomarkers. Antibiotic intervention during PM_2.5 exposure alleviated pulmonary inflammation and oxidative damage in mice. The pulmonary microbiota also showed substantial changes after antibiotic treatment, as reflected by the increased microbiota diversity, decreased abundance of Proteobacteria and increased abundance of Bacteroidota. These results suggest that pulmonary microbial dysbiosis can promote and affect pulmonary inflammation and oxidative stress during PM_2.5 exposure.

Recent Advances in Fungal Infections: From Lung Ecology to Therapeutic Strategies With a Focus on Aspergillus spp

Fungal infections are estimated to be the main cause of death for more than 1.5 million people worldwide annually. However, fungal pathogenicity has been largely neglected. This is notably the case for pulmonary fungal infections, which are difficult to diagnose and to treat. We are currently facing a global emergence of antifungal resistance, which decreases the chances of survival for affected patients. New therapeutic approaches are therefore needed to face these life-threatening fungal infections. In this review, we will provide a general overview on respiratory fungal infections, with a focus on fungi of the genus Aspergillus. Next, the immunological and microbiological mechanisms of fungal pathogenesis will be discussed. The role of the respiratory mycobiota and its interactions with the bacterial microbiota on lung fungal infections will be presented from an ecological perspective. Finally, we will focus on existing and future innovative approaches for the treatment of respiratory fungal infections.

Modulation of hyaluronan signaling as a therapeutic target in human disease

The extracellular matrix is an active participant, modulator and mediator of the cell, tissue, organ and organismal response to injury. Recent research has highlighted the role of hyaluronan, an abundant glycosaminoglycan constituent of the extracellular matrix, in many fundamental biological processes underpinning homeostasis and disease development. From this basis, emerging studies have demonstrated the therapeutic potential of strategies which target hyaluronan synthesis, biology and signaling, with significant promise as therapeutics for a variety of inflammatory and immune diseases. This review summarizes the state of the art in this field and discusses challenges and opportunities in what could emerge as a new class of therapeutic agents, that we term "matrix biologics".

PTX3 Deficiency Promotes Enhanced Accumulation and Function of CD11c+CD11b+ DCs in a Murine Model of Allergic Inflammation

PTX3 is a unique member of the long pentraxins family and plays an indispensable role in regulating the immune system. We previously showed that PTX3 deletion aggravates allergic inflammation via a Th17 -dominant phenotype and enhanced CD4 T cell survival using a murine model of ovalbumin (OVA) induced allergic inflammation. In this study, we identified that upon OVA exposure, increased infiltration of CD11c⁺CD11b⁺ dendritic cells (DCs) was observed in the lungs of PTX3^-/- mice compared to wild type littermate. Further analysis showed that a short-term OVA exposure led to an increased number of bone marrow common myeloid progenitors (CMP) population concomitantly with increased Ly6C^high CCR2^high monocytes and CD11c⁺CD11b⁺ DCs in the lungs. Also, pulmonary CD11c⁺CD11b⁺ DCs from OVA-exposed PTX3^-/- mice exhibited enhanced expression of maturation markers, chemokines receptors CCR2, and increased OVA uptake and processing compared to wild type controls. Taken together, our data suggest that PTX3 deficiency heightened lung CD11c⁺CD11b⁺DC numbers and function, hence exacerbating airway inflammatory response.

PTX3 Regulation of Inflammation, Hemostatic Response, Tissue Repair, and Resolution of Fibrosis Favors a Role in Limiting Idiopathic Pulmonary Fibrosis

PTX3 is a soluble pattern recognition molecule (PRM) belonging to the humoral innate immune system, rapidly produced at inflammatory sites by phagocytes and stromal cells in response to infection or tissue injury. PTX3 interacts with microbial moieties and selected pathogens, with molecules of the complement and hemostatic systems, and with extracellular matrix (ECM) components. In wound sites, PTX3 interacts with fibrin and plasminogen and favors a timely removal of fibrin-rich ECM for an efficient tissue repair. Idiopathic Pulmonary Fibrosis (IPF) is a chronic and progressive interstitial lung disease of unknown origin, associated with excessive ECM deposition affecting tissue architecture, with irreversible loss of lung function and impact on the patient's life quality. Maccarinelli et al. recently demonstrated a protective role of PTX3 using the bleomycin (BLM)-induced experimental model of lung fibrosis, in line with the reported role of PTX3 in tissue repair. However, the mechanisms and therapeutic potential of PTX3 in IPF remained to be investigated. Herein, we provide new insights on the possible role of PTX3 in the development of IPF and BLM-induced lung fibrosis. In mice, PTX3-deficiency was associated with worsening of the disease and with impaired fibrin removal and subsequently increased collagen deposition. In IPF patients, microarray data indicated a down-regulation of PTX3 expression, thus suggesting a potential rational underlying the development of disease. Therefore, we provide new insights for considering PTX3 as a possible target molecule underlying therapeutic intervention in IPF.

New Insights on the Role of pentraxin-3 in Allergic Asthma

Pentraxins are soluble pattern recognition receptors that play a major role in regulating innate immune responses. Through their interaction with complement components, Fcγ receptors, and different microbial moieties, Pentraxins cause an amplification of the inflammatory response. Pentraxin-3 is of particular interest since it was identified as a biomarker for several immune-pathological diseases. In allergic asthma, pentraxin-3 is produced by immune and structural cells and is up-regulated by pro-asthmatic cytokines such as TNFα and IL-1β. Strikingly, some recent experimental evidence demonstrated a protective role of pentraxin-3 in chronic airway inflammatory diseases such as allergic asthma. Indeed, reduced pentraxin-3 levels have been associated with neutrophilic inflammation, Th17 immune response, insensitivity to standard therapeutics and a severe form of the disease. In this review, we will summarize the current knowledge of the role of pentraxin-3 in innate immune response and discuss the protective role of pentraxin-3 in allergic asthma.

Bronchoalveolar lavage cytokine-based risk stratification of minimal acute rejection in clinically stable lung transplant recipients

BACKGROUND

Acute cellular rejection (ACR) remains the most significant risk factor for chronic lung allograft dysfunction (CLAD). While clinically significant or higher-grade (≥A2) ACR is generally treated with augmented immunosuppression (IS), the management of clinically stable grade A1 ACR remains controversial. At our center, patients with clinically stable grade A1 ACR are routinely not treated with augmented IS. While the overall outcomes in this group of patients at our center are equivalent to patients with stable A0 pathology, CLAD and death rates remain overall high. We hypothesized that a distinct cytokine signature at the time of early minimal rejection state would be associated with worse outcomes. Specifically, we aimed to determine whether bronchoalveolar lavage (BAL) biomarkers at the time of first clinically stable grade A1 ACR (CSA1R) are predictive of subsequent CLAD or death.

METHODS

Among all adult, bilateral, first lung transplants, performed 2010-2016, transbronchial biopsies obtained within the first-year post-transplant were categorized as clinically stable or unstable based on the presence or absence of ≥10% concurrent drop in forced expiratory volume in 1 second (FEV₁). We assessed BAL samples obtained at the time of CSA1R episodes, which were not preceded by another ACR (i.e., first episodes). Twenty-one proteins previously associated with ACR or CLAD were measured in the BAL using a multiplex bead assay. Association between protein levels and subsequent CLAD or death was assessed using Cox Proportional Hazards models, adjusted for relevant peri-transplant clinical covariates.

RESULTS

We identified 75 patients with first CSA1R occurring at a median time of 98 days (range 48.5-197) post-transplant. Median time from transplant to CLAD or death was 1247 (756.5-1921.5) and 1641 days (1024.5-2326.5), respectively. In multivariable models, levels of MCP1/CCL2, S100A8, IL10, TNF-receptor 1, and pentraxin 3 (PTX3) were associated with both CLAD development and death (p < 0.05 for all). PTX3 remained significantly associated with both CLAD and death after adjusting for multiple comparisons.

CONCLUSION

Our data indicate that a focused BAL protein signature, with PTX3 having the strongest association, may be useful in determining a subset of CSA1R patients at increased risk and may benefit from a more aggressive management strategy.

Concentration-dependent health effects of air pollution in controlled human exposures

BACKGROUND

Air pollution is a leading contributor to premature mortality worldwide and is often represented by particulate matter (PM), a key contributor to its harmful health effects. Concentration-response relationships are useful for quantifying the effects of air pollution in relevant populations and in considering potential effect thresholds. Controlled human exposures can provide data on acute effects and concentration-response relationships that complement epidemiological studies.

OBJECTIVES

We examined PM concentration-responses after controlled human air pollution exposures to examine exposure-response markers, assess effect modifiers, and identify potential effect thresholds.

METHODS

We reviewed primary research from published controlled human exposure studies where responses were reported at multiple target PM concentrations or summarized per unit change in PM to identify concentration-dependent effects.

RESULTS

Of the 191 publications identified through PubMed and supplementary searches, 31 were eligible. Eligible studies collectively represented four pollutant models: concentrated ambient particles, engineered carbon nanoparticles, diesel exhaust, and woodsmoke. We identified concentration-dependent effects on oxidative stress markers, inflammation, and cardiovascular function that overlapped across different pollutants. Metabolic syndrome and glutathione s-transferase mu 1 genotype were identified as potential effect modifiers.

DISCUSSION

Improved understanding of concentration-response relationships is integral to biomonitoring and mitigation of health effects through impact assessment and policy. Although we identified potential concentration-response markers, thresholds, and modifiers, our conclusions on these relationships were limited by a dearth of eligible publications, considerable variability in methodology, and inconsistent reporting standards between studies. More research is required to validate these observations. We recommend that future studies harmonize estimate reporting to facilitate the identification of robust response markers across research and applied settings.

Pentraxin 3 acts as a functional effector of Akt/NF-κB signaling to modulate the progression and cisplatin-resistance in non-small cell lung cancer

Pentraxin 3 (PTX3) has been documented to be involved in the development of chemoresistance, however, the mechanisms by which it regulates cisplatin (DDP) resistance in non-small cell lung cancer (NSCLC) have never been elucidated. Quantitative reverse transcriptase polymerase chain reaction and Western blot were carried to determine the expression of PTX3, ATP-binding cassette sub-family B member 1 (ABCB1)/P-glycoprotein 1 (p-gp), protein kinase B (Akt), phosphorylated Akt and nuclear factor-kappa B (NF-кB) p65. The biological roles of PTX3 in NSCLC progression and NSCLC cell resistance to DDP were evaluated using enzyme-linked immunosorbent assay, cell count kit-8, colony formation assay, flow cytometry, as well as xenograft tumor assay. The expression of PTX3 was increased in the serum of NSCLC patients as well as in NSCLC cell lines. Lower PTX3 level was associated with longer overall survival in lung adenocarcinoma and lung squamous cell carcinoma patients. Furthermore, PTX3 expression was greatly higher in DDP-resistant NSCLC cells than that in NSCLC cells. Silencing of PTX3 restrained the proliferation and promoted the apoptosis of NSCLC cells, as well as sensitized DDP-resistant NSCLC cells to DDP. Additionally, knockdown of PTX3 inhibited the growth of NSCLC tumors in vivo. Upregulation of PTX3 expression was dependent on the activation of Akt/NF-κB signaling. The induction of apoptosis by PTX3 knockdown was enhanced by MK-2206 or JSH-23. In conclusion, knockdown of PTX3 restrained the progression of NSCLC and sensitized NSCLC cells towards DDP, which provides a potential target to restore DDP chemoresponse.

Endogenous Long Pentraxin 3 Exerts a Protective Role in a Murine Model of Pulmonary Fibrosis

Pulmonary fibrosis is a progressive scarring disease of the lungs, characterized by inflammation, fibroblast activation, and deposition of extracellular matrix. The long pentraxin 3 (PTX3) is a member of the pentraxin family with non-redundant functions in innate immune responses, tissue repair, and haemostasis. The role played in the lungs by PTX3 during the fibrotic process has not been elucidated. In this study, the impact of PTX3 expression on lung fibrosis was assessed in an intratracheal bleomycin (BLM)-induced murine model of the disease applied to wild type animals, transgenic mice characterized by endothelial overexpression and stromal accumulation of PTX3 (Tie2-PTX3 mice), and genetically deficient Ptx3^−/− animals. Our data demonstrate that PTX3 is produced during BLM-induced fibrosis in wild type mice, and that PTX3 accumulation in the stroma compartment of Tie2-PTX3 mice limits the formation of fibrotic tissue in the lungs, with reduced fibroblast activation and collagen deposition, and a decrease in the recruitment of the immune infiltrate. Conversely, Ptx3-null mice showed an exacerbated fibrotic response and decreased survival in response to BLM treatment. These results underline the protective role of endogenous PTX3 during lung fibrosis and pave the way for the study of novel PTX3-derived therapeutic approaches to the disease.

Soluble pattern recognition molecules: Guardians and regulators of homeostasis at airway mucosal surfaces

Maintenance of homeostasis at body barriers that are constantly challenged by microbes, toxins and potentially bioactive (macro)molecules requires complex, highly orchestrated mechanisms of protection. Recent discoveries in respiratory research have shed light on the unprecedented role of airway epithelial cells (AEC), which, besides immune cells homing to the lung, also significantly contribute to host defence by expressing membrane‐bound and soluble pattern recognition receptors (sPRR). Recent evidence suggests that distinct, evolutionary ancient, sPRR secreted by AEC might become activated by usually innocuous proteins, commonly referred to as allergens. We here provide a systematic overview on sPRR detectable in the mucus lining of AEC. Some of them become actively produced and secreted by AECs (like the pentraxins C‐reactive protein and pentraxin 3; the collectins mannose binding protein and surfactant proteins A and D; H‐ficolin; serum amyloid A; and the complement components C3 and C5). Others are elaborated by innate and adaptive immune cells such as monocytes/macrophages and T cells (like the pentraxins C‐reactive protein and pentraxin 3; L‐ficolin; serum amyloid A; and the complement components C3 and C5). Herein we discuss how sPRRs may contribute to homeostasis but sometimes also to overt disease (e.g. airway hyperreactivity and asthma) at the alveolar–air interface.

Red Grape Polyphenol Oral Administration Improves Immune Response in Women Affected by Nickel-Mediated Allergic Contact Dermatitis

BACKGROUND

Our previous findings demonstrated that in vitro supplementation of polyphenols, extracted from seeds of red grape (Nero di Troia cultivar), to peripheral lymphomonocytes from patients affected by allergic contact dermatitis (ACD) to nickel (Ni) could reduce the release of proinflammatory cytokines and nitric oxide (NO), while increasing the levels of interleukin (IL)-10, an anti-inflammatory cytokine.

OBJECTIVE

To assess whether an intervention with oral administration of polyphenols leads to a reduction of peripheral biomarkers in ACD patients.

METHODS

At T0, 25 patients affected by ACD to Ni were orally administered with 300 mg polyphenols prodie extracted from seeds of red grape (Nero di Troia cultivar) (NATUR-OX®) for 3 months (T1). The other 25 patients affected by ACD to Ni received placebo only for the same period of time. Serum biomarkers were analyzed at T0 and T1. In both groups, seven dropouts were recorded.

RESULTS

At T1 in comparison to T0, in treated patients, values of interferon-γ, IL-4, IL-17, pentraxin 3 and NO decreased, while IL-10 levels increased when compared with T0 values. Conversely, in placebo- treated patients, no modifications of biomarkers were evaluated at T1.

CONCLUSION

Present laboratory data rely on the anti-oxidant, anti-inflammatory and anti-allergic properties of polyphenols.

Bariatric surgery results in restoration of physiological plasma levels of pentraxine-3

Pentraxine-3 (PTX3) is a member of the humoral innate immune system and serves a role in protection against infections, inflammation control and matrix deposition. The aim of the present study was to measure the PTX3 levels in obese patients and its association with glycemic and lipid profiles, and to analyze the effects of weight loss provided by bariatric surgery in serum PTX3 levels. PTX3 was measured in 84 obese patients whom underwent bariatric surgery and 94 healthy controls. Lipid and glycemic profiles were determined using a clinical chemistry analyzer, and PTX3 levels were measured in patients prior to and following bariatric surgery using ELISA. PTX3 levels prior to surgery were significantly lower compared with the normal controls (median of 0.10 vs. 0.80 ng/ml; P<0.0001). Following surgery, the median weight loss was 33.1 kg, and the median PTX3 levels were significantly increased to 1.45 ng/ml compared with pre-surgery levels (P<0.001) and did not differ significantly from the control group levels (P=0.10). There were no correlations between PTX3 levels and total cholesterol, HDL and LDL, fasting glycemia, HbA1c and basal insulin levels. A significant positive correlation was observed between PTX3 levels and triglycerides levels in the post-operative period (ρ=0.26, P=0.01). In conclusion, obese patients had lower levels of PTX3 compared with the control patients, and the levels were restored to physiological levels following bariatric surgery which may be associated with the weight loss.

Tunicamycin enhances the suppressive effects of cisplatin on lung cancer growth through PTX3 glycosylation via AKT/NF-κB signaling pathway

Long pentraxin-3 (PTX3) is an inflammatory molecule related to cancer proliferation, invasion, and metastasis. Many studies have highlighted the significance of glycosylated molecules in immune modulation, inflammation and cancer progression. Moreover, aberrant glycosylation of cancer cells is linked to chemoresistance. This study aimed to develop effective therapeutic strategies for deglycosylation of PTX3 (dePTX3) in order to enhance chemosensitivity to cisplatin (Cis) in lung cancer treatment. The A549 and SPCA1 cells were used to determine the role of PTX3 glycosylation in lung cancer growth. Our results revealed that PTX3 was higher in both human lung cancer tissues and serum in comparison with control. Furthermore, we found that deglycosylated PTX3 (dePTX3) by tunicamycin (TM), which is N-glycan precursor biosynthesis blocker, and PNGase F significantly reduced the survival and migration of lung cancer cells. To further confirm this, we also generated glycosylation-site mutant of PTX3 (mPTX3) to characterize the loss of glyco-function. dePTX3 and TM enhanced the suppressive effects of Cis on lung cancer cell growth, migration and invasion compared to individual treatment. Treatment with a combination of TM and Cis significantly inactivated AKT/NF-κB signaling pathway and induced apoptosis. In conclusion, these findings suggest that PTX3 is an important mediator of lung cancer progression, and dePTX3 by TM enhances the anticancer effects of Cis. The deglycosylation in chemotherapy may represent a potential novel therapeutic strategy against lung cancer.

Hyaluronan interactions with innate immunity in lung biology

Lung disease is a leading cause of morbidity and mortality worldwide. Innate immune responses in the lung play a central role in the pathogenesis of lung disease and the maintenance of lung health, and thus it is crucial to understand factors that regulate them. Hyaluronan is ubiquitous in the lung, and its expression is increased following lung injury and in disease states. Furthermore, hyaladherins like inter-α-inhibitor, tumor necrosis factor-stimulated gene 6, pentraxin 3 and versican are also induced and help form a dynamic hyaluronan matrix in injured lung. This review synthesizes present knowledge about the interactions of hyaluronan and its associated hyaladherins with the lung immune system, and the implications of these interactions for lung biology and disease.

Long pentraxin PTX3 mediates acute inflammatory responses against pneumococcal infection

Streptococcus pneumoniae is an important human pathogen responsible for more than 2 million deaths annually worldwide. The airway epithelium acts as the first-line of defense against pneumococcal infections by regulating acute inflammation against invading pneumococcus. Despite the intact adaptive immunity, failure in early defense due to loss of pattern recognition receptors (PRRs) and/or acute phase proteins (APPs) results in detrimental damage and death. C-reactive protein (CRP), the first found APP, is a member of the pentraxin family of proteins and an important soluble PRR for pneumococcus. CRP and another short pentraxin, serum amyloid P, are critical for acute defense against pneumococcal infection. However, the role of the long pentraxin PTX3 in regulating pneumococcal infections is unknown. In this study, PTX3 expression was upregulated by pneumococcus in epithelial cells and in lungs of mice. In addition, PTX3 potentiated pneumococcal inflammation; overexpression of PTX3 enhanced pneumococcus-induced cytokine expression, whereas knock-down of PTX3 with siPTX3 inhibited the cytokine expression. Furthermore, PTX3 deficiency indeed ameliorated acute inflammation and protected mice against death following pneumococcal infection. Pneumococcal toxin pneumolysin was responsible for PTX3 expression and upregulated PTX3 expression via JNK MAPK signaling. These data implicate PTX3 as a novel therapeutic target for the control of acute inflammation by pneumococcus.

Investigating the role of pentraxin 3 as a biomarker for bacterial infection in subjects with COPD

Background

Pentraxin 3 (PTX3) is an acute phase protein, involved in antibacterial resistance. Recent studies have shown PTX3 levels to be elevated in the presence of a bacterial infection and in a murine sepsis model.

Objective

We aim to investigate if sputum PTX3 can be used as a biomarker for bacterial infection in subjects with COPD.

Materials and methods

Sputum samples from 142 COPD patients (102 men) with a mean (range) age of 69 years (45–85) and mean (SD) post-bronchodilator percentage predicted forced expiratory volume in 1 second (FEV₁) of 50% (19) were analyzed for PTX3, using a commercial assay at stable state and during an exacerbation. Association with bacteria, from culture, quantitative real-time polymerase chain reaction (qPCR) and colony-forming units (CFU) was investigated.

Results

The geometric mean (95% CI) PTX3 level at stable state was 50.5 ng/mL (41.4–61.7). PTX3 levels correlated with absolute neutrophil count in sputum (r=0.37; P<0.01), but not FEV₁ or health status. There was a weak correlation between PTX3 and bacterial load (CFU: r=0.29, P<0.01; 16S qPCR: r=0.18, P=0.05). PTX3 was a poor predictor of bacterial colonization (defined as >10⁵ CFU/mL at stable state) with a receiver-operating characteristic (ROC) area under the curve (AUC) of 0.59 and 95% confidence interval (CI) 0.43–0.76 (P=0.21). During an exacerbation, there was a modest increase in PTX3 (fold difference 0.15, 95% of difference 0.02–0.29; P=0.02), and PTX3 fared better at identifying a bacteria-associated exacerbation (ROC AUC 0.65, 95% CI 0.52–0.78, P=0.03).

Conclusion

PTX3 is associated with bacterial infection in patients with COPD, but its utility as a biomarker for identifying a bacteria-associated exacerbation warrants further studies.

Impaired calcineurin signaling in myeloid cells results in downregulation of pentraxin-3 and increased susceptibility to aspergillosis

Treatment of post-transplant patients with immunosuppressive drugs targeting the calcineurin-nuclear factor of activated T cells (NFAT) pathway, including cyclosporine A or tacrolimus, is commonly associated with a higher incidence of opportunistic infections, such as Aspergillus fumigatus, which can lead to severe life-threatening conditions. A component of the A. fumigatus cell wall, β-glucan, is recognized by dendritic cells (DCs) via the Dectin-1 receptor, triggering downstream signaling that leads to calcineurin-NFAT binding, NFAT translocation, and transcription of NFAT-regulated genes. Here, we address the question of whether calcineurin signaling in CD11c-expressing cells, such as DCs, has a specific role in the innate control of A. fumigatus. Impairment of calcineurin in CD11c-expressing cells (CD11c^crecnb1^loxP) significantly increased susceptibility to systemic A. fumigatus infection and to intranasal infection in irradiated mice undergoing bone marrow transplant. Global expression profiling of bone marrow-derived DCs identified calcineurin-regulated processes in the immune response to infection, including expression of pentraxin-3, an important antifungal defense protein. These results suggest that calcineurin inhibition directly impairs important immunoprotective functions of myeloid cells, as shown by the higher susceptibility of CD11c^crecnb^loxP mice in models of systemic and invasive pulmonary aspergillosis, including after allogeneic bone marrow transplantation. These findings are relevant to the clinical management of transplant patients with severe Aspergillus infections.

Particulate matter-mediated release of long pentraxin 3 (PTX3) and vascular endothelial growth factor (VEGF) in vitro: Limited importance of endotoxin and organic content

Exposure to particulate matter (PM) is associated with adverse health effects, but it is still relatively unknown which role PM sources and physicochemical properties play in the observed effects. It was postulated that PM in vitro induces release of long pentraxin 3 (PTX3) and vascular endothelial growth factor (VEGF) and that endotoxin and organic compounds present in the PM regulate this release. A contact coculture of THP-1 human leukemia monocytes and A549 human adenocarcinoma alveolar pneumocytes was exposed to PM from Traffic, Wood, Diesel, and Quartz (10-40 µg/cm²) for 12-64 h to determine release of PTX3 and VEGF. The role of endotoxin and the organic fraction in the mediator release was assessed using polymyxin B sulfate and organic extracts, respectively. Finally, antagonists were used to investigate whether the early proinflammatory cytokines interleukin (IL)-1 and tumor necrosis factor (TNF)-α affected the PTX3 and VEGF release. All PM samples induced a time-dependent release of both PTX3 and VEGF. Traffic mediated the greatest release of PTX3, whereas Wood and Diesel were more potent inducers of VEGF. The endotoxin content did not markedly affect release of either mediator, while the organic fraction exerted no significant effect on VEGF release and limited influence on PTX3 release. In addition, the IL-1 and TNF-α agonists affected PTX3 release more strongly than VEGF release. In conclusion, the current data show a limited impact of endotoxin and organic compounds on PTX3 and VEGF release. Further, the observed differences in response patterns may point toward differential regulation of PM-mediated release of PTX3 and VEGF.

Pentraxin 3 deletion aggravates allergic inflammation through a TH17-dominant phenotype and enhanced CD4 T-cell survival

Background

Pentraxin 3 (PTX3) is a multifunctional molecule that plays a nonredundant role at the crossroads between pathogen clearance, innate immune system, matrix deposition, female fertility, and vascular biology. It is produced at sites of infection and inflammation by both structural and inflammatory cells. However, its role in allergen-induced inflammation remains to be tested.

Objective

We sought to determine the effect of Ptx3 deletion on ovalbumin (OVA)–induced allergic inflammation in a murine model of asthma.

Methods

Bronchoalveolar lavage fluid was collected from patients with severe asthma and healthy subjects, and the level of PTX3 was determined by using ELISA. Ptx3^+/+ and Ptx3^−/− mice were sensitized and challenged with OVA and bronchoalveolar lavage fluid, and the lungs were collected for assessing inflammation. Lung tissue inflammation and mucus production were assessed by means of flow cytometry and hematoxylin and eosin and periodic acid-Schiff staining, respectively. flexiVent was used to determine airway resistance to methacholine in these mice.

Results

Here we report that mice with severe asthma and OVA-sensitized/challenged mice had increased PTX3 levels in the lungs compared with healthy control mice. Mice lacking PTX3 have exaggerated neutrophilic/eosinophilic lung inflammation, mucus production, and airway hyperresponsiveness in an experimental model of OVA-induced asthma. Furthermore, OVA-exposed lung Ptx3^−/− CD4 T cells exhibit an increased production of IL-17A, an effect that is accompanied by an increased signal transducer and activator of transcription 3 phosphorylation, reduced IL-2 production, and enhanced activation and survival. Also, we observed an increase in numbers of IL-6– and IL-23–producing dendritic cells in OVA-exposed Ptx3^−/− mice compared with those in wild-type control mice.

Conclusion

Altogether, PTX3 deficiency results in augmented airway hyperresponsiveness, mucus production, and IL-17A–dominant pulmonary inflammation, suggesting a regulatory role of PTX3 in the development of allergic inflammation.

In silico Analysis Revealed High-risk Single Nucleotide Polymorphisms in Human Pentraxin-3 Gene and their Impact on Innate Immune Response against Microbial Pathogens

Pentraxin-3 (PTX-3) protein is an evolutionary conserved protein that acts as a soluble pattern-recognition receptor for pathogens and plays important role in innate immune response. It recognizes various pathogens by interacting with extracellular moieties such as glactomannan of conidia (Aspergillus fumigatus), lipopolysaccharide of Pseudomonas aeruginosa, Streptococcus pneumonia and Salmonella typhimurium. Thus, PTX-3 protein helps to clear these pathogens by activating downstream innate immune process. In this study, computational methods were used to analyze various non-synonymous single nucleotide polymorphisms (nsSNPs) in PTX-3 gene. Three different databases were used to retrieve SNP data sets followed by seven different in silico algorithms to screen nsSNPs in PTX-3 gene. Sequence homology based approach was used to identify nsSNPs. Conservation profile of PTX-3 protein amino acid residues were predicted by ConSurf web server. In total, 10 high-risk nsSNPs were identified in pentraxin-domain of PTX-3 gene. Out of these 10 high-risk nsSNPs, 4 were present in the conserved structural and functional residues of the pentraxin-domain, hence, selected for structural analyses. The results showed alteration in the putative structure of pentraxin-domain. Prediction of protein–protein interactions analysis showed association of PTX-3 protein with C1q component of complement pathway. Different functional and structural residues along with various putative phosphorylation sites and evolutionary relationship were also predicted for PTX-3 protein. This is the first extensive computational analyses of pentraxin protein family with nsSNPs and will serve as a valuable resource for future population based studies.

IL-6 trans-signaling increases expression of airways disease genes in airway smooth muscle

Genetic data suggest that IL-6 trans-signaling may have a pathogenic role in the lung; however, the effects of IL-6 trans-signaling on lung effector cells have not been investigated. In this study, human airway smooth muscle (HASM) cells were treated with IL-6 (classical) or IL-6+sIL6R (trans-signaling) for 24 h and gene expression was measured by RNAseq. Intracellular signaling and transcription factor activation were assessed by Western blotting and luciferase assay, respectively. The functional effect of IL-6 trans-signaling was determined by proliferation assay. IL-6 trans-signaling had no effect on phosphoinositide-3 kinase and Erk MAP kinase pathways in HASM cells. Both classical and IL-6 trans-signaling in HASM involves activation of Stat3. However, the kinetics of Stat3 phosphorylation by IL-6 trans-signaling was different than classical IL-6 signaling. This was further reflected in the differential gene expression profile by IL-6 trans-signaling in HASM cells. Under IL-6 trans-signaling conditions 36 genes were upregulated, including PLA2G2A, IL13RA1, MUC1, and SOD2. Four genes, including CCL11, were downregulated at least twofold. The expression of 112 genes was divergent between IL-6 classical and trans-signaling, including the genes HILPDA, NNMT, DAB2, MUC1, WWC1, and VEGFA. Pathway analysis revealed that IL-6 trans-signaling induced expression of genes involved in regulation of airway remodeling, immune response, hypoxia, and glucose metabolism. Treatment of HASM cells with IL-6+sIL6R induced proliferation in a dose-dependent fashion, suggesting a role for IL-6 trans-signaling in asthma pathogenesis. These novel findings demonstrate differential effect of IL-6 trans-signaling on airway cells and identify IL-6 trans-signaling as a potential modifier of airway inflammation and remodeling.

The long pentraxin PTX3 promotes fibrocyte differentiation

Monocyte-derived, fibroblast-like cells called fibrocytes are associated with fibrotic lesions. The plasma protein serum amyloid P component (SAP; also known as pentraxin-2, PTX2) inhibits fibrocyte differentiation in vitro, and injections of SAP inhibit fibrosis in vivo. SAP is a member of the pentraxin family of proteins that includes C-reactive protein (CRP; PTX1) and pentraxin-3 (PTX3). All three pentraxins are associated with fibrosis, but only SAP and CRP have been studied for their effects on fibrocyte differentiation. We find that compared to SAP and CRP, PTX3 promotes human and murine fibrocyte differentiation. The effect of PTX3 is dependent on FcγRI. In competition studies, the fibrocyte-inhibitory activity of SAP is dominant over PTX3. Binding competition studies indicate that SAP and PTX3 bind human FcγRI at different sites. In murine models of lung fibrosis, PTX3 is present in fibrotic areas, and the PTX3 distribution is associated with collagen deposition. In lung tissue from pulmonary fibrosis patients, PTX3 has a widespread distribution, both in unaffected tissue and in fibrotic lesions, whereas SAP is restricted to areas adjacent to vessels, and absent from fibrotic areas. These data suggest that the relative levels of SAP and PTX3 present at sites of fibrosis may have a significant effect on the ability of monocytes to differentiate into fibrocytes.