In situ localization of TNFalpha/beta, TACE and TNF receptors TNF-R1 and TNF-R2 in control and LPS-treated lung tissue

Elaboration of chitosan nanoparticles loaded with star anise extract as a therapeutic system for lung cancer: Physicochemical and biological evaluation

The research study aimed to maximize the important medical role of star anise extract (SAE) through its loading on a widely available natural polymer (chitosan, Cs). Thus, SAE loaded chitosan nanoparticles (CsNPs) was prepared. The finding illustrated the formation of spherical particles of SAE loaded CsNPs as proved by transmission electron microscope (TEM). In addition, the average particle size of CsNPs and SAE loaded CsNPs are 131.8 ± 24.63 and 318.5 ± 73.94 nm, respectively. Scanning electron microscope (SEM) showed the presence of many spherical particles deposited on the surface of CsNPs owing to the deposition of SAE on the surface and encapsulated into pores of CsNPs. It also showed the presence of elements such as sodium, potassium, copper, magnesium, zinc, calcium, and iron, as well as the elements that accompanied with CsNPs: carbon, oxygen, nitrogen, and phosphorus. The extract was rich in bioactive components, such as anethole, shikimic acid, and different flavonoids, contributing to its medicinal qualities. The bioactive molecules in SAE were assessed by chromatographic analysis. Using the agar well diffusion test, the antibacterial qualities of CsNPs and SAE loaded CsNPs were evaluated against pathogenic bacteria linked to lung illnesses. The most significant inhibition zones showed that the SAE loaded CsNPs had the most antibacterial activity. The anticancer activity using MTT assay was used in the biological assessments to determine the cytotoxicity against the NCl-H460 lung cancer cell line. The results showed that CsNPs loaded with SAE considerably decreased cell viability in a dose-dependent manner, with the most significant anticancer impact by SAE loaded CsNPs. Furthermore, in vivo tests on lung cancer therapy revealed that when compared to other treatment groups, the SAE loaded CsNPs group showed the greatest reduction in tumor biomarkers and inflammation, as seen by decreased levels of Plasma malondialdehyde (MDA), tumor protein 53 (p53), Tumor necrosis factor-alpha (TNF- alpha), and fibronectin. Results concluded that these thorough characterizations, biological assessments, and antibacterial tests have confirmed the effective integration of SAE into CsNPs. Further, SAE loaded CsNPs could be a suitable option for various biomedical applications in tackling lung cancer and the inactivation of bacterial infection.

Susceptibility to recombinant SARS-CoV-2 spike protein entry in the lungs of high-fat diet-induced obese mice

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Obesity is a major risk factor for the development of COVID-19. Angiotensin-converting enzyme 2 (ACE2) is an essential receptor for cell entry of SARS-CoV-2. The receptor-binding domain of the S1 subunit (S1-RBD protein) in the SARS-CoV-2 spike glycoprotein binds to ACE2 on host cells, through which the virus enters several organs, including the lungs. Considering these findings, recombinant ACE2 might be utilized as a decoy protein to attenuate SARS-CoV-2 infection. Here, we examined whether obesity increases ACE2 expression in the lungs and whether recombinant ACE2 administration diminishes the entry of S1-RBD protein into lung cells. We observed that high-fat diet-induced obesity promoted ACE2 expression in the lungs by increasing serum levels of LPS derived from the intestine. S1-RBD protein entered the lungs specifically through ACE2 expressed in host lungs and that the administration of recombinant ACE2 attenuated this entry. We conclude that obesity makes hosts susceptible to recombinant SARS-CoV-2 spike proteins due to elevated ACE2 expression in lungs, and this model of administering S1-RBD protein can be applied to new COVID-19 treatments.

Current research status of blood biomarkers in Alzheimer's disease: Diagnosis and prognosis

Alzheimer's disease (AD), which mainly occurs in the elderly, is a neurodegenerative disease with a hidden onset, which leads to progressive cognitive and behavioral changes. The annually increasing prevalence rate and number of patients with AD exert great pressure on the society. No effective disease-modifying drug treatments are available; thus, there is no cure yet. The disease progression can only be delayed through early detection and drug assistance. Therefore, the importance of exploring associated biomarkers for the early diagnosis and prediction of the disease progress is highlighted. The National Institute on Aging- Alzheimer's Association (NIA-AA) proposed A/T/N diagnostic criteria in 2018, including Aβ42, p-tau, t-tau in cerebrospinal fluid (CSF), and positron emission tomography (PET). However, the invasiveness of lumbar puncture for CSF assessment and non-popularity of PET have prompted researchers to look for minimally invasive, easy to collect, and cost-effective biomarkers. Therefore, studies have largely focused on some novel molecules in the peripheral blood. This is an emerging research field, facing many obstacles and challenges while achieving some promising results.

TNFα and Immune Checkpoint Inhibition: Friend or Foe for Lung Cancer?

Tumor necrosis factor-alpha (TNFα) can bind two distinct receptors (TNFR1/2). The transmembrane form (tmTNFα) preferentially binds to TNFR2. Upon tmTNFα cleavage by the TNF-alpha-converting enzyme (TACE), its soluble (sTNFα) form is released with higher affinity for TNFR1. This assortment empowers TNFα with a plethora of opposing roles in the processes of tumor cell survival (and apoptosis) and anti-tumor immune stimulation (and suppression), in addition to angiogenesis and metastases. Its functions and biomarker potential to predict cancer progression and response to immunotherapy are reviewed here, with a focus on lung cancer. By mining existing sequencing data, we further demonstrate that the expression levels of TNF and TACE are significantly decreased in lung adenocarcinoma patients, while the TNFR1/TNFR2 balance are increased. We conclude that the biomarker potential of TNFα alone will most likely not provide conclusive findings, but that TACE could have a key role along with the delicate balance of sTNFα/tmTNFα as well as TNFR1/TNFR2, hence stressing the importance of more research into the potential of rationalized treatments that combine TNFα pathway modulators with immunotherapy for lung cancer patients.

Genotoxicity linked to occupational exposure in uranium mine workers: Granzyme B and apoptotic changes

BACKGROUND

Uranium mining and processing are an ancient occupation, recognized as being grueling and accountable for injury and disease. Uranium (U) is a radioactive heavy metal used in many industrial applications. It increases the micronuclei frequencies as well as chromosomal aberration and sister chromatid exchange in peripheral blood lymphocytes. Granzyme B and perforin are stored inside the leukocytes in secretory granules. These proteins are released outside the cells by a cell-to-cell contact under specific conditions for inducing apoptosis. So, this study investigated the potential health hazards with prominence on the biological effects of radiation exposure.

METHODS

A cross-sectional analytic research was conducted on Egyptian male mining field workers. Leucocytes' genotoxicity was evaluated using DNA fragmentation assay and comet assay. Furthermore, flow cytometric analysis of Granzyme B protein was done.

RESULTS

A significant increase in dead cells after dual acridine orange/ethidium bromide (AO/EB) fluorescent staining in radiation-exposed groups was noticed compared to control groups. Moreover, a significant increase in the fragmented DNA was evident in exposed groups relative to the control one. Granzyme B protein levels showed a significant increase concerning control.

CONCLUSION

A wide variety of adverse human health risks are considered a potential risk to Egyptian uranium miners. For employers working in both mining and processing fields, the most common molecular shift highlighted was the leucocyte damage in blood samples. To preserve the health of all employees, health education and administration of effective hazard management procedures are necessary.

TNF receptors are associated with tau pathology and conversion to Alzheimer's dementia in subjects with mild cognitive impairment

BACKGROUND

Tumor necrosis factor-a (TNF-α) signaling pathway plays a significant role in Alzheimer's disease (AD). This study aimed to explore the relationship between TNF-α related inflammatory proteins and pathological markers of AD, and examine their possibility as a predictor of the conversion of mild cognitive impairment (MCI) to AD.

METHODS

This study included both cross-sectional and longitudinal designs. The levels of TNF-α related inflammatory proteins, Aβ_1-42, total-tau(t-tau), phosphorylated tau (p-tau) from cerebrospinal fluid (CSF) were analyzed in healthy controls (HC, n = 90), MCI (n = 116), and AD participants (n = 75) from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Kaplan-Meier analyses were used to evaluate the predictive value of the examined putative AD markers after follow-up visits.

RESULTS

In the cross-sectional cohort, we observed higher CSF levels of TNF-α related inflammatory proteins in the MCI and AD patients with positive tau pathology. TNF receptors (TNFR) were more closely associated with t-tau and p-tau than Aβ_1-42, in HC, MCI and AD subjects. In the longitudinal cohort with a mean follow-up of 30.2 months, MCI patients with high levels of CSF TNFR1 (p = 0.001) and low levels of TNFR2 (p < 0.001) were more likely to develop into AD.

CONCLUSION

TNFR-signaling might be involved in the early pathogenesis of AD and TNF receptors may serve as potential predictive biomarkers for MCI.

Potential Mechanisms of 3, 4-Oxo-Isopropylidene-Shikimic Acid in Ameliorating 2, 4, 6-Trinitrobenzenesulfonic Acid-Induced Colitis in Rats

Previously, we reported that 3, 4-oxo-isopropylidene-shikimic acid (ISA) has therapeutic potential in experimental colitis in rats. This study aimed to elucidate the potential mechanisms of ISA on the inflammatory response in rats with 2, 4, 6-trinitrobenzenesulfonic acid-induced colitis. After the induction of colitis, rats were orally administered ISA for 12 days. Then, the expression levels of inflammatory cytokines, cell adhesion molecules, and matrix metalloproteinase (MMP) in the blood and colon tissues, and the protein level of nuclear factor kappa B (NF-κB) p65 in cytoplasm and nucleus of colon tissues were evaluated. As a result, an enhanced inflammatory response was observed in rats with experimental colitis. However, the treatment with ISA significantly ameliorated the inflammatory response, which was manifested as a significant decrease in the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interferon (IFN)-γ, IL-8, TNF-α mRNA, P-selectin, E-selectin, intercellular cell adhesion molecule-1, MMP9 and MMP9 mRNA in rat blood and colon tissues, respectively, and a significant decrease in the levels of IFN-γ/IL-4, and the NF-κBp65 activity coefficient. Therefore, the therapeutic effect of ISA on experimental colitis may be related to its inhibitory effect on the expression of cytokines, adhesion molecules, and MMP9, which may be involved in the inhibition of the activation and nuclear translocation of NF-κBp65.

The role of NF-κB and Elk-1 in the regulation of mouse ADAM17 expression

ADAM17 is a cell membrane metalloproteinase responsible for the release of ectodomains of numerous proteins from the cell surface. Although ADAM17 is often overexpressed in tumours and at sites of inflammation, little is known about the regulation of its expression. Here we investigate the role of NF-κB and Elk-1 transcription factors and upstream signalling pathways, NF-κB and ERK1/2 in ADAM17 expression in mouse brain endothelial cells stimulated with pro-inflammatory factors (TNF, IL-1β, LPS) or a phorbol ester (PMA), a well-known stimulator of ADAM17 activity. Notably, NF-κB inhibitor, IKK VII, interfered with the IL-1β- and LPS-mediated stimulation of ADAM17 expression. Furthermore, Adam17 promoter contains an NF-κB binding site occupied by p65 subunit of NF-κB. The transient increase in Adam17 mRNA in response to PMA was strongly reduced by an inhibitor of ERK1/2 phosphorylation, U0126. Luciferase reporter assay with vectors encoding the ERK1/2 substrate, Elk-1, fused with constitutively activating or repressing domains, indicated Elk-1 involvement in Adam17 expression. The site-directed mutagenesis of potential Elk-1 binding sites pointed to four functional Elk-1 binding sites in Adam17 promoter. All in all, our results indicate that NF-κB and Elk-1 transcription factors via NF-κB and ERK1/2 signalling pathways contribute to the regulation of mouse Adam17 expression.

Summary: We show the involvement of ERK1/2 and NF-κB pathways in the stimulation of mouse Adam17 expression and determine functional Elk-1- and NF-κB binding sites in its promoter.

The roles of microRNAs in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive and irreversible airflow obstruction, with an abnormal lung function. The etiology of COPD correlates with complex interactions between environmental and genetic determinants. However, the exact pathogenesis of COPD is obscure although it involves multiple aspects including oxidative stress, imbalance between proteolytic and anti-proteolytic activity, immunity and inflammation, apoptosis, and repair and destruction in both airways and lungs. Many genes have been demonstrated to be involved in those pathogenic processes of this disease in patients exposed to harmful environmental factors. Previous reports have investigated promising microRNAs (miRNAs) to disclose the molecular mechanisms for COPD development induced by different environmental exposure and genetic predisposition encounter, and find some potential miRNA biomarkers for early diagnosis and treatment targets of COPD. In this review, we summarized the expression profiles of the reported miRNAs from studies of COPD associated with environmental risk factors including cigarette smoking and air pollution exposures, and provided an overview of roles of those miRNAs in the pathogenesis of the disease. We also highlighted the potential utility and limitations of miRNAs serving as diagnostic biomarkers and therapeutic targets for COPD.

Sub-chronic inhalation of reclaimed water-induced fibrotic lesion in a mouse model

When reclaimed water is used as municipal miscellaneous water, acute exposure of the generated aerosol with high levels of endotoxins can cause severe inflammation in the lungs. However, the potential risks of long-term inhalation of reclaimed water remains unclear. To identify the adverse effects of sub-chronic reclaimed water inhalation and explain the underlying mechanisms, a mouse model of 12-week sub-chronic exposure was established, and wastewater before a membrane bioreactor (MBR, positive control) and the MBR effluent (reclaimed water, which met the quality standard of urban use and was currently used for landscape irrigation) were tested in this study. The exposure dose was set to approach the real working scenarios. Lung lavage and histology were analyzed. Obvious epithelial cell apoptosis in the bronchi was observed, along with the accumulation of myofibroblasts and the collagen deposition both in main bronchi and terminal bronchioles. All these symptoms were persistent after 4 weeks of recovery. Inflammation and induced bronchus-associated lymphoid tissues (iBALT) were also observed but diminished after recovery indicating inflammation may not be the direct cause of the symptom. Furthermore, two fibrogenic cytokines (TNF-α and TGF-β) were constantly high in the lung during the study. They might be the biomarkers of lung damage after the inhalation of reclaimed water. Adaptive immune responses were also detected as elevated levels of IgG and IgA, but not for IgE. Inhalation of reclaimed water causes sustained fibrotic lesions in the lungs, which suggests potential health risks during urban application where aerosols generated.

ADAM-17 is expressed in the inflammatory myopathy and is involved with interstitial lung disease

The "A disintegrin and metalloprotease" (ADAM) family is thought to play an important role in tissue destruction and inflammatory reactions. ADAM-17 was first described as the protease responsible for tumor necrosis factor (TNF)-α shedding. Here, we have shown the expression of ADAM-17 in inflammatory myopathy and demonstrated the role of inflammation in interstitial lung diseases (ILD). ADAM-17 in inflammatory myopathy serum [polymyositis (n = 26), dermatomyositis (n = 34), and clinically amyopathic dermatomyositis (n = 10)] and healthy control (n = 19) was measured using enzyme-linked immunosorbent assay. The relationship between ADAM-17 and clinical data was examined. Finally, we performed immunohistological analysis to investigate the expression of ADAM-17 on the muscles of the inflammatory myopathy patients. ADAM-17 in inflammatory myopathy was significantly higher than that in healthy control (mean ± SEM, 1048 ± 312 and 36 ± 18 pg/ml, respectively; p < 0.05). ADAM-17 in post-treatment with corticosteroid and/or immunosuppressant serum was significantly decreased compared with that in pre-treatment serum (1465 ± 562 and 1059 ± 503 pg/ml, respectively; p < 0.01). ADAM-17 was significantly positively correlated with fractalkine/CX3CL1 and CXCL16. In addition, ADAM-17 in inflammatory myopathy with ILD patients (n = 46) was significantly higher than that in non-ILD patients (n = 24) (1379 ± 454 and 413 ± 226 pg/ml, respectively; p < 0.05). We found the expression of ADAM-17 on muscle biopsy tissue. ADAM-17 is expressed in inflammatory myopathies especially ILD, suggesting that ADAM-17 plays a role in lung fibrosis. ADAM-17 may be a potential target in inflammatory myopathies with ILD.

The EGFR-ADAM17 Axis in Chronic Obstructive Pulmonary Disease and Cystic Fibrosis Lung Pathology

Chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) share molecular mechanisms that cause the pathological symptoms they have in common. Here, we review evidence suggesting that hyperactivity of the EGFR/ADAM17 axis plays a role in the development of chronic lung disease in both CF and COPD. The ubiquitous transmembrane protease A disintegrin and metalloprotease 17 (ADAM17) forms a functional unit with the EGF receptor (EGFR), in a feedback loop interaction labeled the ADAM17/EGFR axis. In airway epithelial cells, ADAM17 sheds multiple soluble signaling proteins by proteolysis, including EGFR ligands such as amphiregulin (AREG), and proinflammatory mediators such as the interleukin 6 coreceptor (IL-6R). This activity can be enhanced by injury, toxins, and receptor-mediated external triggers. In addition to intracellular kinases, the extracellular glutathione-dependent redox potential controls ADAM17 shedding. Thus, the epithelial ADAM17/EGFR axis serves as a receptor of incoming luminal stress signals, relaying these to neighboring and underlying cells, which plays an important role in the resolution of lung injury and inflammation. We review evidence that congenital CFTR deficiency in CF and reduced CFTR activity in chronic COPD may cause enhanced ADAM17/EGFR signaling through a defect in glutathione secretion. In future studies, these complex interactions and the options for pharmaceutical interventions will be further investigated.

Anti-TNFα therapy in inflammatory lung diseases

Increased levels of tumor necrosis factor (TNF) α have been linked to a number of pulmonary inflammatory diseases including asthma, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), sarcoidosis, and interstitial pulmonary fibrosis (IPF). TNFα plays multiple roles in disease pathology by inducing an accumulation of inflammatory cells, stimulating the generation of inflammatory mediators, and causing oxidative and nitrosative stress, airway hyperresponsiveness and tissue remodeling. TNFα-targeting biologics, therefore, present a potentially highly efficacious treatment option. This review summarizes current knowledge on the role of TNFα in pulmonary disease pathologies, with a focus on the therapeutic potential of TNFα-targeting agents in treating inflammatory lung diseases.

Innate myeloid cell TNFR1 mediates first line defence against primary Mycobacterium tuberculosis infection

TNF is crucial for controlling Mycobacterium tuberculosis infection and understanding how will help immunomodulating the host response. Here we assessed the contribution of TNFR1 pathway from innate myeloid versus T cells. We first established the prominent role of TNFR1 in haematopoietic cells for controlling M. tuberculosis in TNFR1 KO chimera mice. Further, absence of TNFR1 specifically on myeloid cells (M-TNFR1 KO) recapitulated the uncontrolled M. tuberculosis infection seen in fully TNFR1 deficient mice, with increased bacterial burden, exacerbated lung inflammation, and rapid death. Pulmonary IL-12p40 over-expression was attributed to a prominent CD11b⁺ Gr1^high cell population in infected M-TNFR1 KO mice. By contrast, absence of TNFR1 on T-cells did not compromise the control of M. tuberculosis infection over 6-months. Thus, the protective TNF/TNFR1 pathway essential for controlling primary M. tuberculosis infection depends on innate macrophage and neutrophil myeloid cells, while TNFR1 pathway in T cells is dispensable.

Molecular dynamics and intracellular signaling of the TNF-R1 with the R92Q mutation

The tumor necrosis factor receptor superfamily, member 1A (TNFRSF1A) gene encodes the TNF-R1, one of the main TNF receptors that mediates its inflammatory actions. In a recent study, serum levels of the soluble TNF-R1 and mRNA levels of the full-length receptor were found to be significantly increased in multiple sclerosis (MS) patients carrying the R92Q mutation. Interestingly, R92Q-mutated patients were younger at disease onset and progressed slower as compared to non-carriers. Building on these previous findings, here we aimed to investigate by means of both in silico and in vitro approaches the mechanisms relating the R92Q substitution with functional changes of the receptor and their potential effects modulating MS disease course. Models of the extracellular domains of the human TNF-R1 and human TNF-R1 carrying the R92Q mutation, alone or bound to TNF, were constructed and submitted to molecular dynamics. TRAF2 and CASP3 mRNA expression levels were determined by real-time PCR in peripheral blood mononuclear cells (PBMC) from 61 MS patients, 9 R92Q carriers and 52 non-carriers (CT and CC genotypes for SNP rs4149584, respectively). Molecular dynamic studies revealed that the R92Q mutation increased the contact area between receptor and TNF (1070 and 1388Å(2) for native and mutated receptor) and decreased the distance between them (28.7 to 27.9Å), while Van der Waals and electrostatic interaction energies were increased. In PBMC from MS patients carrying the R92Q mutation, CASP3 mRNA expression levels were significantly increased compared to non-carriers, whereas a trend was observed for TRAF2. These data suggest that the R92Q mutation gives rise to a stronger interaction between the receptor and its ligand, which results in the potentiation of TNF-mediated pathways. Although further studies are needed, these functional changes may be related with the modulation in disease course reported in MS patients carrying the R92Q mutation.

Increased plasma TACE activity in subjects with mild cognitive impairment and patients with Alzheimer's disease

Evidence suggests that the tumor necrosis factor receptor (TNFR)-signaling pathway contributes to the pathogenesis of Alzheimer's disease (AD). TNF-α converting enzyme (TACE/ADAM-17) can cleave both pro-TNF-α and TNF receptors. Recently, we have shown that TACE activity in the cerebrospinal fluid (CSF) of subjects with mild cognitive impairment (MCI) and AD patients is significantly higher than that of cognitively healthy controls (HC). To date, it is not clear whether TACE activity could be detected in the human plasma and whether TACE activity in MCI and AD patients is different from that in HC. We analyzed TACE expression and activity in a large clinical sample of 64 patients with AD, 88 subjects with MCI, and 50 age-matched HC recruited from two distinct academic centers. Plasma TACE protein levels did not differ significantly in the three study groups (AD, MCI, and HC). However, plasma TACE activity in subjects with MCI and AD patients was significantly higher than that in HC. Moreover, in MCI and AD groups, we found a significant correlation between plasma TACE activity and CSF t-tau and Aβ42 levels and CSF Aβ42/tau ratios. In AD patients, the levels of plasma TACE activity correlated significantly and negatively with cognition. These findings further support the role of the TNF-α receptor complex in AD-related neuroinflammation and propose TACE plasma activity as a promising hypothesis-driven biomarker candidate for detection, diagnosis, and prognosis of prodromal and clinical AD.

Anti-inflammatory effects of a novel non-antibiotic macrolide, EM900, on mucus secretion of airway epithelium

OBJECTIVE

Low-dose, long-term use of 14-membered macrolides is effective for treatment of patients with chronic airway inflammation such as diffuse panbronchiolitis or chronic rhinosinusitis. However, long-term use of macrolides can promote the growth of drug-resistant bacteria, and the development of anti-inflammatory macrolides that lack antibiotic effects is desirable. Previously, we developed EM900, a novel 12-membered erythromycin A derivative, which has potent anti-inflammatory and immunomodulatory activities and lacks any antibacterial activity. We examined the anti-inflammatory effects of EM900 on mucus secretion from airway epithelial cells.

METHODS

To examine the in vivo effects of EM900 on airway inflammation, we induced hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium via intranasal instillation of lipopolysaccharides. In vitro effects of EM900 on airway epithelial cells were examined using cultured human airway epithelial (NCI-H292) cells. Mucus secretion was evaluated via enzyme-linked immunosorbent assays with an anti-MUC5AC monoclonal antibody.

RESULTS

Oral administration of EM900 or clarithromycin (CAM) significantly inhibited LPS-induced mucus production from rat nasal epithelium. EM900, CAM, or erythromycin significantly inhibited MUC5AC secretion induced by tumor necrosis factor-α from NCI-H292 cells. MUC5AC mRNA expression was also significantly lower in EM900-treated cells.

CONCLUSION

These results indicated that a novel non-antibiotic macrolide, EM900 exerted direct inhibitory effects on mucus secretion from airway epithelial cells, and that it may have the potential to become a new anti-inflammatory drug for the treatment of chronic rhinosinusitis.

ADAM-family metalloproteinases in lung inflammation: potential therapeutic targets

Acute and chronic lung inflammation is driven and controlled by several endogenous mediators that undergo proteolytic conversion from surface-expressed proteins to soluble variants by a disintegrin and metalloproteinase (ADAM)-family members. TNF and epidermal growth factor receptor ligands are just some of the many substrates by which these proteases regulate inflammatory or regenerative processes in the lung. ADAM10 and ADAM17 are the most prominent members of this protease family. They are constitutively expressed in most lung cells and, as recent research has shown, are the pivotal shedding enzymes mediating acute lung inflammation in a cell-specific manner. ADAM17 promotes endothelial and epithelial permeability, transendothelial leukocyte migration, and inflammatory mediator production by smooth muscle and epithelial cells. ADAM10 is critical for leukocyte migration and alveolar leukocyte recruitment. ADAM10 also promotes allergic asthma by driving B cell responses. Additionally, ADAM10 acts as a receptor for Staphylococcus aureus (S. aureus) α-toxin and is crucial for bacterial virulence. ADAM8, ADAM9, ADAM15, and ADAM33 are upregulated during acute or chronic lung inflammation, and recent functional or genetic analyses have linked them to disease development. Pharmacological inhibitors that allow us to locally or systemically target and differentiate ADAM-family members in the lung suppress acute and asthmatic inflammatory responses and S. aureus virulence. These promising results encourage further research to develop therapeutic strategies based on selected ADAMs. These studies need also to address the role of the ADAMs in repair and regeneration in the lung to identify further therapeutic opportunities and possible side effects.

Tumor necrosis factor-alpha-converting enzyme activities and tumor-associated macrophages in breast cancer

The role of the tumor microenvironment especially of tumor-associated macrophages (TAMs) in the progression and metastatic spread of breast cancer is well established. TAMs have primarily a M2 (wound-healing) phenotype with minimal cytotoxic activities. The mechanisms by which tumor cells influence TAMs to display a pro-tumor phenotype are still debated although the key roles of immunomodulatory cytokines released by tumor cells, including colony-stimulating factor 1, tumor necrosis factor (TNF) and soluble TNF receptors 1/2, soluble vascular cell adhesion molecule 1, soluble interleukin 6 receptor and amphiregulin, have been demonstrated. Importantly, these factors are released through ectodomain shedding by the activities of the tumor necrosis factor-alpha-converting enzyme (TACE/ADAM17). The role of TACE activation leading to autocrine effects on tumor progression has been extensively studied. In contrast, limited information is available on the role of tumor cell TACE activities on TAMs in breast cancer. TACE inhibitors, currently in clinical trials, will certainly affect TAMs and subsequently treatment outcomes based on the substrates it releases. Furthermore, whether targeting a subset of the molecules shed by TACE, specifically those leading to TAMs with altered functions and phenotype, holds greater therapeutic promises than past clinical trials of TACE antagonists' remains to be determined. Here, the potential roles of TACE ectodomain shedding in the breast tumor microenvironment are reviewed with a focus on the release of tumor-derived immunomodulatory factors shed by TACE that directs TAM phenotypes and functions.

ADAM17 at the interface between inflammation and autoimmunity

The discovery of the disintegrin and metalloproteinase 17 (ADAM17), originally identified as tumor necrosis factor-a converting enzyme (TACE) for its ability as sheddase of TNF-α inspired scientists to attempt to elucidate the molecular mechanisms underlying ADAM17 implication in diseased conditions. In recent years, it has become evident that this protease can modify many non matrix substrates, such as cytokines (e.g. TNF-α), cytokine receptors (e.g. IL-6R and TNF-R), ligands of ErbB (e.g. TGF-α and amphiregulin) and adhesion proteins (e.g. Lselectin and ICAM-1). Several recent studies have described experimental model system to better understand the role of specific signaling molecules, the interplay of different signals and tissue interactions in regulating ADAM17-dependent cleavage of most relevant substrates in inflammatory diseases. The central question is whether ADAM17 can influence the outcome of inflammation and if so, how it performs this regulation in autoimmunity, since inflammatory autoimmune diseases are often characterized by deregulated metalloproteinase activities. This review will explore the latest research on the influence of ADAM17 on the progression of inflammatory processes linked to autoimmunity and its role as modulator of inflammation.

Combination of plasma tumor necrosis factor receptors signaling proteins, beta-amyloid and apolipoprotein E for the detection of Alzheimer's disease

Activation of inflammatory processes has been observed within the brain as well as periphery of subjects with Alzheimer's disease (AD). Among several putative neuroinflammatory mechanisms, the tumor necrosis factor-α (TNF-α) signaling system plays a central role. TNF-α converting enzyme (TACE) does not only cleave pro-TNF-α but also TNF receptors, however, whether the TACE activity and soluble TNF receptors (sTNFRs) were changed in the plasma were not clear. The aim of this study was to determine whether the levels of TACE activity and sTNFRs are sufficiently altered in the plasma of AD patients to be helpful in AD diagnosis. We examined TACE levels in the plasma of 153 patients with AD, 98 patients with amnestic mild cognitive impairment (aMCI), 53 patients with vascular dementia (VaD), and 120 age-matched healthy control subjects, and found TACE activity and sTNFRs were significantly higher in patients with AD and aMCI compared with control subjects (TACE: P<0.001, P<0.01; sTNFR1: P<0.001, P<0.001; sTNFR2: P<0.001, P<0.01, respectively). The TACE activity and sTNFRs levels in VaD patients were significantly higher than the levels observed in AD patients (TACE activity: P<0.001, sTNFR1: P<0.01, sTNFR2: P<0.01). In the plasma of AD patients, the levels of both TACE activity and sTNFRs positively correlated with the levels of Aβ40 and negatively correlated with the ratio of Aβ42/Aβ40. AD patients with at least one copy of the ApoEε4 allele showed higher TACE activity and sTNFR plasma levels compared with patients without the ApoEε4 allele. We then combined the data on plasma TACE activity, sTNFRs, and Aβ with the presence of the APOEε4 allele and found that this biomarker panel exhibited a high sensitivity and specificity for discriminating AD patients from non-demented control subjects and VaD patients.

Effects of lipopolysaccharide on the response of C57BL/6J mice to whole thorax irradiation

BACKGROUND AND PURPOSE

Inflammatory and fibrogenic processes play a crucial role in the radiation-induced injury in the lung. The aim of the present study was to examine whether additive LPS exposure in the lung (to simulate respiratory infection) would affect pneumonitis or fibrosis associated with lung irradiation.

MATERIAL AND METHODS

Wildtype C57Bl/6J (WT-C57) and TNFα, TNFR1 and TNFR2 knockout ((-/-)) mice, in C57Bl/6J background, were given whole thorax irradiation (10 Gy) with or without post-irradiation intratracheal administration of LPS (50μg/mice). Functional deficit was examined by measuring breathing rate at various times after treatment. Real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and immunohistochemistry were used to analyze the protein expression and m-RNA of Interleukin-1 alpha (IL-1α), Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), Tumour Necrosis Factor alpha (TNFα) and Transforming Growth Factor beta (TGFβ) in the lung at various times after treatment. Inflammatory cells were detected by Mac-3 (macrophages) and Toluidine Blue (mast cells) staining. Collagen content was estimated by hydroxyproline (total collagen) and Sircol assay (soluble collagen). Levels of oxidative damage were assessed by 8-hydroxy-2-deoxyguanosine (8-OHdG) staining.

RESULTS

LPS exposure significantly attenuated the breathing rate increases following irradiation of WT-C57, TNFR1(-/-) and TNFR2(-/-)mice and to a lesser extent in TNFα(-/-) mice. Collagen content was significantly reduced after LPS treatment in WT-C57, TNFR1(-/-) and TNFα(-/-) mice and there was a trend in TNFR2(-/-) mice. Similarly there were lower levels of inflammatory cells and cytokines in the LPS treated mice.

CONCLUSIONS

This study reveals a mitigating effect of early exposure to LPS on injury caused by irradiation on lungs of C57Bl mice. The results suggest that immediate infection post irradiation may not impact lung response negatively in radiation-accident victims, however, further studies are required in different animal models, and with specific infectious agents, to confirm and extend our findings.

Inhibition of the transcription factor c-Jun by the MAPK family, and not the NF-κB pathway, suggests that peanut extract has anti-inflammatory properties

BACKGROUND

Tumor necrosis factor-α (TNF-α) is involved in inflammatory responses in atherosclerosis. We propose an in vitro cellular assay to evaluate the anti-inflammatory mechanisms of potential modifiers such as food extracts. In the current model we assessed an anti-inflammatory effect of polyphenol-rich peanut extract in lipopolysaccharide (LPS)-induced THP-1 monocytes.

METHODS

THP-1 monocytes were incubated with peanut extract (5, 25, 50 and 100 μg/mL) consisting of 39% flavonols, 37% flavanols and 24% phenolic acid (or BAY 11-7082 (5 μM) as experiment control) for 1 h and then stimulated with LPS (500 ng/mL) for 4 h. Cytotoxicity was measured as lactate dehydrogenase (LDH) activity release. NF-κB and MAPK family were determined by TransAm kit while TNF-α mRNA levels and its mRNA stability by RT-PCR. Intra- and extracellular TNF-α protein was measured by ELISA, and TNF-α converting enzyme (TACE) activity by a fluorimetric assay.

RESULTS

Peanut extract inhibited the maximal LPS-induced extracellular TNF-α protein secretion by 18%, 29% and 47% at 25, 50 and 100 μg/mL, respectively (P<0.05). LPS stimulation revealed that 85% of TNF-α was released extracellularly while 15% remained intracellular. Peanut extract did not modify NF-κB but, instead, reduced c-Jun transcription factor activity (P<0.05), decreased TNF-α mRNA (albeit non-significantly) and had no effect on mRNA stability and TACE activity.

CONCLUSION

Polyphenol-rich peanut extract reduces extracellular TNF-α protein by inhibiting c-Jun transcription factor from MAPK family, suggesting an anti-inflammatory effect. The proposed THP-1 monocyte model could be used to assess food extract impact (site and size effects) on the inflammation pathway.

Azithromycin inhibits mucus hypersecretion from airway epithelial cells

To examine the in vivo effects of the 15-member macrolide, azithromycin (AZM), on mucus hypersecretion, we induced hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium by intranasal instillation of ovalbumin (OVA) in OVA-sensitized rats, or by intranasal lipopolysaccharides (LPS) instillation. Oral administration of AZM (5–10 mg/kg) or clarithromycin (CAM, 5–10 mg/kg) significantly inhibited OVA- and LPS-induced mucus production, whereas josamycin (JM) or ampicillin (ABPC) showed no effect. In vitro effects of AZM on airway epithelial cells were examined using NCI-H292 cells and human nasal epithelial cells cultured in air-liquid interface. Mucus secretion was evaluated by enzyme-linked immunosorbent assay using an anti-MUC5AC monoclonal antibody. AZM or CAM significantly inhibited tumor necrosis factor-α (TNF-α) (20 ng/mL)-induced MUC5AC secretion from NCI-H292 cells at 10⁻⁶–10⁻⁷ M, whereas JM or ABPC showed no effect. AZM significantly inhibited TNF-α (20 ng/mL)-induced MUC5AC secretion from human nasal epithelial cells at 10⁻⁴ M. MUC5AC mRNA expression was also significantly inhibited. These results indicate that the 15-member macrolide, AZM, exerts direct inhibitory effects on mucus secretion from airway epithelial cells and that it may be useful for the treatment of mucus hypersecretion caused by allergic inflammation and LPS stimulation.

Elevated CSF levels of TACE activity and soluble TNF receptors in subjects with mild cognitive impairment and patients with Alzheimer's disease

We recently reported that expression levels of tumor necrosis factor (TNF) receptors, TNFR1 and TNFR2, are significantly changed in the brains and cerebrospinal fluid (CSF) with Alzheimer's disease (AD). Moreover, we also found that, in an Alzheimer's mouse model, genetic deletion of TNF receptor (TNFR1) reduces amyloid plaques and amyloid beta peptides (Aβ) production through β-secretase (BACE1) regulation. TNF-α converting enzyme (TACE/ADAM-17) does not only cleave pro- TNF-α but also TNF receptors, however, whether the TACE activity was changed in the CSF was not clear. In this study, we examined TACE in the CSF in 32 AD patients and 27 age-matched healthy controls (HCs). Interestingly, we found that TACE activity was significantly elevated in the CSF from AD patients compared with HCs. Furthermore, we also assayed the CSF levels of TACE cleaved soluble forms of TNFR1 and TNFR2 in the same patients. We found that AD patients had higher levels of both TACE cleaved soluble TNFR1 (sTNFR1) and TNFR2 (sTNFR2) in the CSF compared to age- and gender-matched healthy controls. Levels of sTNFR1 correlated strongly with the levels of sTNFR2 (rs = 0.567-0.663, p < 0.01). The levels of both sTNFR1 and sTNFR2 significantly correlated with the TACE activity (rs = 0.491-0.557, p < 0.05). To examine if changes in TACE activity and in levels of cleaved soluble TNFRs are an early event in the course of AD, we measured these molecules in the CSF from 47 subjects with mild cognitive impairment (MCI), which is considered as a preclinical stage of AD. Unexpectedly, we found significantly higher levels of TACE activity and soluble TNFRs in the MCI group than that in AD patients. These results suggest that TACE activity and soluble TNF receptors may be potential diagnostic candidate biomarkers in AD and MCI.

The evolving experience with therapeutic TNF inhibition in sepsis: considering the potential influence of risk of death

INTRODUCTION

Septic shock is highly lethal and its incidence is increasing. Although TNF-α plays a key role in sepsis pathogenesis, past efforts to therapeutically inhibit it had limited success. However, there is continued interest in such therapies and there are now ongoing Phase II sepsis trials testing the effects of AZD9773, a TNF-directed polyclonal antibody fragment preparation. Experience with anti-inflammatory agents suggested that their efficacy may relate to sepsis-associated risk of death.

AREAS COVERED

An overview of the biology of TNF and experimental data implicating TNF as a key mediator in sepsis pathogenesis; a review of the earlier clinical experience with anti-TNF therapies demonstrating that when examined across 12 trials, these agents had a highly consistent overall effect which although not reaching significance, was on the side of benefit; a review of data showing that sepsis-associated risk of death may influence the efficacy of anti-inflammatory agents like anti-TNF ones and a review of the rational and clinical experience to date with AZD9773 and its precursor, CytoFab.

EXPERT OPINION

Discusses variables that may need to be accounted for to maximize the success of clinical trials in sepsis testing agents that modulate host inflammation.

Sources of alveolar soluble TNF receptors during acute lung injury of different etiologies

Elevated soluble tumor necrosis factor-α receptor (sTNFR) levels in bronchoalveolar lavage fluid (BALF) are associated with poor patient outcome in acute lung injury (ALI). The mechanisms underlying these increases are unknown, but it is possible that pulmonary inflammation and increased alveolar epithelial permeability may individually contribute. We investigated mechanisms of elevated BALF sTNFRs in two in vivo mouse models of ALI. Anesthetized mice were challenged with intratracheal lipopolysaccharide or subjected to injurious mechanical ventilation. Lipopolysaccharide instillation produced acute intra-alveolar inflammation, but minimal alveolar epithelial permeability changes, with increased BALF sTNFR p75, but not p55. Increased p75 levels were markedly attenuated by alveolar macrophage depletion. In contrast, injurious ventilation induced substantial alveolar epithelial permeability, with increased BALF p75 and p55, which strongly correlated with total protein. BALF sTNFRs were not increased in isolated buffer-perfused lungs (devoid of circulating sTNFRs) subjected to injurious ventilation. These results suggest that lipopolysaccharide-induced intra-alveolar inflammation upregulates alveolar macrophage-mediated production of sTNFR p75, whereas enhanced alveolar epithelial permeability following mechanical ventilation leads to increased BALF p75 and p55 via plasma leakage. These data provide new insights into differential regulation of intra-alveolar sTNFR levels during ALI and may suggest sTNFRs as potential markers for evaluating the pathophysiology of ALI.

Characterization of TNF receptor subtype expression and signaling on pulmonary endothelial cells in mice

TNF plays a crucial role in the pathogenesis of acute lung injury. However, the expression profile of its two receptors, p55 and p75, on pulmonary endothelium and their influence on TNF signaling during lung microvascular inflammation remain uncertain. Using flow cytometry, we characterized the expression profile of TNF receptors on the surface of freshly harvested pulmonary endothelial cells (PECs) from mice and found expression of both receptors with dominance of p55. To investigate the impact of stimulating individual TNF receptors, we treated wild-type and TNF receptor knockout mice with intravenous TNF and determined surface expression of adhesion molecules (E-selectin, VCAM-1, ICAM-1) on PECs by flow cytometry. TNF-induced upregulation of all adhesion molecules was substantially attenuated by absence of p55, whereas lack of p75 had a similar but smaller effect that varied between adhesion molecules. Selective blockade of individual TNF receptors by specific antibodies in wild-type primary PEC culture confirmed that the in vivo findings were due to direct effects of TNF receptor inhibition on endothelium and not other cells (e.g., circulating leukocytes). Finally, we found that PEC surface expression of p55 dramatically decreased in the early stages of endotoxemia following intravenous LPS, while no change in p75 expression was detected. These data demonstrate a crucial in vivo role of p55 and an auxiliary role of p75 in TNF-mediated adhesion molecule upregulation on PECs. It is possible that the importance of the individual receptors varies at different stages of pulmonary microvascular inflammation following changes in their relative expression.

Role of TNFR1 in lung injury and altered lung function induced by the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide

Lung toxicity induced by sulfur mustard is associated with inflammation and oxidative stress. To elucidate mechanisms mediating pulmonary damage, we used 2-chloroethyl ethyl sulfide (CEES), a model sulfur mustard vesicant. Male mice (B6129) were treated intratracheally with CEES (3 or 6 mg/kg) or control. Animals were sacrificed 3, 7 or 14 days later and bronchoalveolar lavage (BAL) fluid and lung tissue collected. Treatment of mice with CEES resulted in an increase in BAL protein, an indication of alveolar epithelial damage, within 3 days. Expression of Ym1, an oxidative stress marker also increased in the lung, along with inducible nitric oxide synthase, and at 14 days, cyclooxygenase-2 and monocyte chemotactic protein-1, inflammatory proteins implicated in tissue injury. These responses were attenuated in mice lacking the p55 receptor for TNFα (TNFR1-/-), demonstrating that signaling via TNFR1 is key to CEES-induced injury, oxidative stress, and inflammation. CEES-induced upregulation of CuZn-superoxide dismutase (SOD) and MnSOD was delayed or absent in TNFR1-/- mice, relative to WT mice, suggesting that TNFα mediates early antioxidant responses to lung toxicants. Treatment of WT mice with CEES also resulted in functional alterations in the lung including decreases in compliance and increases in elastance. Additionally, methacholine-induced alterations in total lung resistance and central airway resistance were dampened by CEES. Loss of TNFR1 resulted in blunted functional responses to CEES. These effects were most notable in the airways. These data suggest that targeting TNFα signaling may be useful in mitigating lung injury, inflammation and functional alterations induced by vesicants.

MicroRNA expression in induced sputum of smokers and patients with chronic obstructive pulmonary disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is characterized by progressive inflammation in the airways and lungs combined with disturbed homeostatic functions of pulmonary cells. MicroRNAs (miRNAs) have the ability to regulate these processes by interfering with gene transcription and translation.

OBJECTIVES

We aimed to identify miRNA expression in induced sputum and examined whether the expression of miRNAs differed between patients with COPD and subjects without airflow limitation.

METHODS

Expression of 627 miRNAs was evaluated in induced sputum supernatant of 32 subjects by stem-loop reverse transcription-quantitative polymerase chain reaction. Differentially expressed miRNAs were validated in an independent replication cohort of 41 subjects. Enrichment of miRNA target genes was identified by in silico analysis. Protein expression of target genes was determined by ELISA.

MEASUREMENTS AND MAIN RESULTS

Thirty-four miRNAs were differentially expressed between never-smokers and current smokers without airflow limitation in the screening cohort. Eight miRNAs were expressed at a significantly lower level in current-smoking patients with COPD compared with never-smokers without airflow limitation. Reduced expression of let-7c and miR-125b in patients with COPD compared with healthy subjects was confirmed in the validation cohort. Target genes of let-7c were significantly enriched in the sputum of patients with severe COPD. The concentration of tumor necrosis factor receptor type II (TNFR-II, implicated in COPD pathogenesis and a predicted target gene of let-7c) was inversely correlated with the sputum levels of let-7c .

CONCLUSIONS

let-7c is significantly reduced in the sputum of currently smoking patients with COPD and is associated with increased expression of TNFR-II.

ADAM-17: the enzyme that does it all

This review focuses on the role of ADAM-17 in disease. Since its debut as the tumor necrosis factor converting enzyme (TACE), ADAM-17 has been reported to be an indispensible regulator of almost every cellular event from proliferation to migration. The central role of ADAM-17 in cell regulation is rooted in its diverse array of substrates: cytokines, growth factors, and their receptors as well as adhesion molecules are activated or inactivated by their cleavage with ADAM-17. It is therefore not surprising that ADAM-17 is implicated in numerous human diseases including cancer, heart disease, diabetes, rheumatoid arthritis, kidney fibrosis, Alzheimer's disease, and is a promising target for future treatments. The specific role of ADAM-17 in the pathophysiology of these diseases is very complex and depends on the cellular context. To exploit the therapeutic potential of ADAM-17, it is important to understand how its activity is regulated and how specific organs and cells can be targeted to inactivate or activate the enzyme.

Studies on the role of acid sphingomyelinase and ceramide in the regulation of tumor necrosis factor alpha (TNFalpha)-converting enzyme activity and TNFalpha secretion in macrophages

Acid sphingomyelinase (ASMase) has been proposed to mediate lipopolysaccharide (LPS) signaling in various cell types. This study shows that ASMase is a negative regulator of LPS-induced tumor necrosis factor alpha (TNFalpha) secretion in macrophages. ASMase-deficient (asm(-/-)) mice and isolated peritoneal macrophages produce severalfold more TNFalpha than their wild-type (asm(+/+)) counterparts when stimulated with LPS, whereas the addition of exogenous ceramides or sphingomyelinase reduces the differences. The underlying mechanism for these effects is not transcriptional but post-translational. The TNFalpha-converting enzyme (TACE) catalyzes the maturation of the 26-kDa precursor (pro-TNFalpha) to an active 17-kDa form (soluble (s)TNFalpha). In mouse peritoneal macrophages, the activity of TACE was the rate-limiting factor regulating TNFalpha production. A substantial portion of the translated pro-TNFalpha was not processed to sTNFalpha; instead, it was rapidly internalized and degraded in the lysosomes. TACE activity was 2-3-fold higher in asm(-/-) macrophages as compared with asm(+/+) macrophages and was suppressed when cells were treated with exogenous ceramide and sphingomyelinase. Indirect immunofluorescence analyses revealed distinct TNFalpha-positive structures in the close vicinity of the plasma membrane in asm(-/-) but not in asm(+/+) macrophages. asm(-/-) cells also had a higher number of early endosomal antigen 1-positive early endosomes. Experiments that involved inhibitors of TACE, endocytosis, and lysosomal proteolysis suggest that in the asm(-/-) cells a significant portion of pro-TNFalpha was sequestered within the early endosomes, and instead of undergoing lysosomal proteolysis, it was recycled to the plasma membrane and processed to sTNFalpha.

Upregulation of tumor necrosis factor receptor 1 and TNF-alpha converting enzyme during corneal wound healing

PURPOSE

To elucidate tumor necrosis factor (TNF) receptor-1 (TNFR1) and TNF-alpha converting enzyme (TACE) involvement during corneal wound healing.

METHODS

The corneas of BALB/c mice cornea were scarred by alkali burns using filter paper dipped in 1N NaOH solution. TACE and TNFR1 expression in the alkali-burned corneas were evaluated by immunohistochemistry (total, 16 eyes). Using cultured fibroblasts (human) and macrophages (mice), we evaluated the release of soluble TNF-alpha (sTNF-alpha) and soluble TNFR1 (sTNFR1) in the supernatant by enzyme-linked immunosorbent assay after stimulating TACE activity with phorbol myristate acetate (PMA).

RESULTS

In alkali-burned corneas, both TACE and TNFR1 expression were observed in the stromal cells after the acute phase of wound healing response. In macrophage-cultured supernatant, both sTNF-alpha and sTNFR1 release were promoted by PMA stimulation. On the other hand, only sTNFR1 released by PMA stimulation was observed in fibroblast-cultured supernatant.

CONCLUSIONS

TACE and TNFR1 were expressed mainly after the acute phase of corneal wound healing. The TACE-dependent extracellular release of sTNFR1 was recognized in cultured fibroblasts and macrophages.

TRAF1 regulates recruitment of lymphocytes and, to a lesser extent, neutrophils, myeloid dendritic cells and monocytes to the lung airways following lipopolysaccharide inhalation

Inhaled lipopolysaccharide (LPS) induces an inflammatory response that may contribute to the pathogenesis of asthma and other airway diseases. Here we investigate the role of tumour necrosis factor (TNF) receptor-associated factor 1 (TRAF1) in leucocyte recruitment using a model of LPS-induced lung inflammation in mice. TRAF1(-/-) mice are completely deficient in the recruitment of lymphocytes to the lower respiratory tract after inhalation of LPS. Although TRAF1(-/-) mice display normal early accumulation of neutrophils, dendritic cells and monocytes in the alveolar airspace, they have a significantly reduced recruitment of these cells by 24 hr after inhalation of LPS when compared to wild-type (WT) mice. Despite normal expression of the pro-inflammatory cytokines TNF, interleukin-1 (IL-1) and IL-6 after LPS treatment, TRAF1(-/-) mice displayed decreased expression of intercellular adhesion molecule 1, vascular cell adhesion molecule 1, CCL17 and CCL20 in the lungs, when compared to LPS-treated WT mice. These results suggest that TRAF1 facilitates LPS-induced leucocyte recruitment into the lung airways by augmenting the expression of chemokines and adhesion molecules. Mice lacking TNF receptor 1 (TNFR1) but not TNFR2 show a phenotype similar to the TRAF1(-/-) mice, suggesting that TRAF1 may act downstream of TNFR1. Significantly, we use bone marrow chimeras to demonstrate that expression of TRAF1 by cells resident in the lungs, but not by circulating leucocytes, is necessary for efficient LPS-induced recruitment of leucocytes to the lung airways.

Differential roles of p55 and p75 tumor necrosis factor receptors on stretch-induced pulmonary edema in mice

Ventilator-induced lung injury plays a crucial role in the outcome of patients with acute lung injury. Previous studies have shown a role for the cytokine tumor necrosis factor-alpha (TNF) in stretch-induced alveolar neutrophil recruitment, but the involvement of TNF in stretch-induced pulmonary edema is unclear. We investigated the effects of TNF through its individual p55 and p75 receptors on early pulmonary edema formation during high stretch ventilation, before neutrophil infiltration. Anesthetized wild-type or TNF receptor single/double knockout mice were ventilated with high tidal volume ( approximately 38 ml/kg) for 2 h or until they developed arterial hypotension. Pulmonary edema was assessed by physiological parameters including respiratory mechanics and blood gases, and by lavage fluid protein, lung wet:dry weight ratio, and lung permeability measurements using fluorescence-labeled albumin. High stretch ventilation in wild-type and TNF receptor double knockout animals induced similar pulmonary edema, and only 25-30% of mice completed the protocol. In contrast, the p55 receptor knockout mice were strongly protected from edema formation, with all animals completing the protocol. Myeloperoxidase assay indicated that this protective effect was not associated with decreased pulmonary neutrophil sequestration. The p75 receptor knockout mice, however, displayed increased susceptibility to edema formation, and no animals survived the full 2 h. These results demonstrate a novel role for TNF signaling (independent from its effects on neutrophil recruitment) specifically through the p55 receptor, in promoting high stretch-induced pulmonary edema, whereas p75 signaling may play an opposing role.

Gene expression profiling in Salmonella Choleraesuis-infected porcine lung using a long oligonucleotide microarray

Understanding the transcriptional response to pathogenic bacterial infection within food animals is of fundamental and applied interest. To determine the transcriptional response to Salmonella enterica serovar Choleraesuis (SC) infection, a 13,297-oligonucleotide swine array was used to analyze RNA from control, 24-h postinoculation (hpi), and 48-hpi porcine lung tissue from pigs infected with SC. In total, 57 genes showed differential expression (p < 0.001; false discovery rate = 12%). Quantitative real-time PCR (qRT-PCR) of 61 genes was used to confirm the microarray results and to identify pathways responding to infection. Of the 33 genes identified by microarray analysis as differentially expressed, 23 were confirmed by qRT-PCR results. A novel finding was that two transglutaminase family genes (TGM1 and TGM3) showed dramatic increases in expression postinoculation; combined with several other apoptotic genes, they indicated the induction of apoptotic pathways during SC infection. A predominant T helper 1-type immune response occurred during infection, with interferon gamma (IFNG) significantly increased at 48 hpi. Genes induced by IFNs (GBP1, GBP2, C1S, C1R, MHC2TA, PSMB8, TAP1, TAP2) showed increased expression during porcine lung infection. These data represent the first thorough investigation of gene regulation pathways that control an important porcine respiratory and foodborne bacterial infection.

(Make) stick and cut loose--disintegrin metalloproteases in development and disease

"A disintegrin and metalloprotease" (ADAM) proteases form a still growing family of about 40 type 1 transmembrane proteins. They are defined by a common modular ectodomain architecture that combines cell deadhesion/adhesion and fusion motifs (disintegrin and cysteine-rich domains), with a Zn-protease domain capped by a large prodomain. Their ectodomain thus strikingly resembles snake venom disintegrin proteases, which by combined integrin blocking and extracellular proteolysis, can cause extensive tissue damage after snake bites. A surprisingly large proportion (13 ADAMs) is exclusively expressed in the male gonads, and only a minority can be found throughout all tissues. As predicted by their amino acid sequence, a major proportion of this family has not maintained a functional protease domain, most probably rendering them into pure adhesion and/or fusion proteins. For most ADAMs, the respective key function has remained elusive. Despite their overall conserved ectodomain structure, ADAMs appear to be subdivided into those with a predominant role in direct adhesion (e.g., ADAMs 1, 2, and 3) and those mainly acting as proteases (e.g., ADAMs 10 and 17). Only for a few of them are functions of more than one domain documented (e.g., ADAM9 in cell fusion and proteolysis). Several ADAMs exist in both membrane-resident and secreted isoforms; the functional significance of this dichotomy is in most cases still unclear. Knockout phenotypes have been informative only in a few cases (ADAMs 1, 2, 10, 12, 15, 17, and 19) and are mainly related to their protease function. A common denominator of ADAM-mediated proteolysis is the ectodomain shedding of a broad spectrum of substrates, including paracrine growth factors like epidermal growth factor receptor (EGFR) ligands, cell adhesion molecules like CD44 or cadherins, and the initiation of regulated intramembrane proteolysis (RIP), whereby the transmembrane fragment of the respective substrate is further cleaved by an intramembrane cleaving protease to release an intracellular domain acting as a nuclear transcription regulator. Most ADAMs feature a significant overlap of substrate specificities, explaining why an inactivation of individual ADAMs only rarely causes major phenotypes.

Both hemopoietic and resident cells are required for MyD88-dependent pulmonary inflammatory response to inhaled endotoxin

Inhaled endotoxin induces an inflammatory response that contributes to the development and severity of asthma and other forms of airway disease. Here, we show that inhaled endotoxin-induced acute bronchoconstriction, TNF, IL-12p40, and KC production, protein leak, and neutrophil recruitment in the lung are abrogated in mice deficient for the adaptor molecule MyD88. Bronchoconstriction, inflammation, and protein leak are normal in Toll/IL-1R domain-containing adaptor inducing IFN-beta-deficient mice. MyD88 is involved in TLR, but also in IL-1R-associated kinase 1-mediated IL-1R and -18R signaling. We exclude a role for IL-1 and IL-18 pathways in this response, as IL-1R1 and caspase-1 (ICE)-deficient mice develop lung inflammation while TLR4-deficient mice are unresponsive to inhaled LPS. Significantly, using bone marrow chimera, we demonstrate that both hemopoietic and resident cells are necessary for a full MyD88-dependent response to inhaled endotoxin; bronchoconstriction depends on resident cells while cytokine secretion is mediated by hemopoietic cells.

The TNF alpha converting enzyme (TACE/ADAM17) is expressed in the atherosclerotic lesions of apolipoprotein E-deficient mice: possible contribution to elevated plasma levels of soluble TNF alpha receptors

TNF alpha converting enzyme (TACE) critically regulates the inflammatory processes as it releases from the cell surface several transmembrane proteins, including TNFalpha (TNF) and its receptors TNFR1 and TNFR2. We investigated the expression of TACE in atherosclerotic lesions of apolipoproteinE-deficient (apoE (-/-)) mice. Five-week-old apoE(-/-) male mice were fed a high-fat diet and examined at 5, 10, 15 and 25 weeks of age. A group of wild-type C57BL/6 mice (WT) fed the high-fat diet for 25 weeks was included. In apoE(-/-) mice, lesions progressed with time in both aortic sinus and arch, in which TACE immunostaining also increased particularly between 5 and 15 weeks. TACE expression was also observed in human atherosclerotic plaques. The plasma levels of soluble TNFR1 and TNFR2 rose with atherosclerosis. In the 25-week-old WT mice, no lesions were observed and the plasma levels of TNFRs were 17% of those of age-matched apoE(-/-) mice. Incubated aortas of 25-week-old apoE(-/-) mice released much higher amounts of sTNF and sTNFRs than did aortas of 5-week-old apoE(-/-) mice or 25-week-old WT mice. Active TACE was expressed at the surface of macrophages isolated from apoE(-/-) mice. In conclusion, TACE expression is associated with lesions in atherosclerosis-prone sites. Our data suggest that atherosclerotic lesions-expressing TACE may contribute to the elevated levels of circulating sTNFRs.

Up regulated expression of tumour necrosis factor {alpha} converting enzyme in peripheral monocytes of patients with early systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is accompanied by abnormalities in humoral and cellular immune systems.

OBJECTIVE

To determine the genes specifically expressed in the immune system in SSc by analysis of the gene expression profile of peripheral blood mononuclear cells (PBMC) from patients with SSc, including those treated with haematopoietic stem cell transplantation (HSCT). Additionally, to investigate the clinical significance of the up regulation of tumour necrosis factor alpha (TNFalpha) converting enzyme (TACE).

METHODS

PBMC from patients with SSc (n = 23) and other autoimmune diseases (systemic lupus erythematosus (SLE, n = 16), rheumatoid arthritis (RA, n = 29)), and from disease-free controls (n = 36) were examined. Complementary DNA arrays were used to evaluate gene expression of PBMC, in combination with real time quantitative polymerase chain reactions. TACE protein expression in PBMC was examined by fluorescence activated cell sorter (FACS).

RESULTS

In patients with SSc 118 genes were down regulated after HSCT. Subsequent comparative analysis of SSc without HSCT and healthy controls indicated SSc-specific up regulation for three genes: monocyte chemoattractant protein-3 (p = 0.0015), macrophage inflammatory protein 3alpha (p = 0.0339), and TACE (p = 0.0251). In the FACS analysis, TACE protein was mainly expressed on CD14(+) monocytes both in patients with SSc and controls. TACE expression on CD14(+) cells was significantly increased in patients with early SSc (p = 0.0096), but not in those with chronic SSc, SLE, or RA. TACE protein levels in SSc monocytes correlated with the intracellular CD68 levels (p = 0.0016).

CONCLUSIONS

Up regulation of TACE expression was a unique profile in early SSc, and may affect the function of TNFalpha and other immunoregulatory molecules.

Inhibition of tumor necrosis factor-alpha-induced RANTES secretion by alkaline protease in A549 cells

Pseudomonas aeruginosa is a gram-negative bacterium that is an opportunistic pathogen in patients with cystic fibrosis and in immunocompromised hosts. This bacterium produces a variety of proteolytic enzymes, including alkaline protease (AP), which has multiple biological effects. This study investigated the effects of AP on the A549 pulmonary epithelial cell line. Results demonstrate that AP inhibited tumor necrosis factor (TNF)-alpha-induced RANTES gene expression and secretion in a concentration-dependent manner. The TNF-alpha-induced RANTES gene expression and secretion was attenuated with a neutralizing monoclonal antibody directed against the TNF receptor type 1 (TNFR1). Conversely, a neutralizing monoclonal antibody directed against TNF receptor type II had no effect, suggesting that these events were regulated through the TNFR1 receptor. In addition, we observed that soluble TNF receptor type 1 (sTNFR1) levels were significantly increased in culture supernatants of AP-treated cells in a concentration-dependent manner. Finally, membrane-associated TNFR1 was decreased after AP exposures. In these studies, the enzymatically inactive form of AP had no effect on TNF-alpha-induced RANTES secretion, shedding of sTNFR1, or membrane-associated TNFR1. These results demonstrate that AP stimulates shedding of cell-surface TNFR1, resulting in an increase in sTNFR1. Consequently, these events decrease the cells' ability to stimulate RANTES gene expression and secretion through TNFR1.

Amino-terminal TACE prodomain attenuates TNFR2 cleavage independently of the cysteine switch

TNF-alpha-converting enzyme (TACE, ADAM17) cleaves membrane-associated cytokines and receptors and thereby regulates inflammatory and immune events, as well as lung development and mucin production. For example, the TACE-mediated cleavage of the type II 75-kDa TNF receptor (TNFR2) generates a soluble TNF-binding protein that modulates TNF bioactivity. TACE is synthesized as a latent proenzyme that is retained in an inactive state via an interaction between its prodomain and catalytic domain. Although the formation of an intramolecular bond between a cysteine in the prodomain and a zinc atom in the catalytic site had been thought to mediate this inhibitory activity, it was recently reported that the cysteine-switch motif is not required. Here, we hypothesized that the amino terminus of the TACE prodomain might contribute to the ability of the prodomain to maintain TACE in an inactive state independently of a cysteine-switch mechanism. We synthesized a 37-amino acid peptide corresponding to TACE amino acids 18-54 (N-TACE(18-54)) and assessed whether it possessed TACE inhibitory activity. In an in vitro model assay system, N-TACE(18-54) attenuated TACE-catalyzed cleavage of a TNFR2:Fc substrate. Furthermore, N-TACE(18-54) inhibited constitutive TNFR2 shedding from a human monocytic cell line by 42%. A 19-amino acid, leucine-rich domain, corresponding to TACE amino acids 30-48, demonstrated partial inhibitory activity. In summary, we have identified a subdomain within the amino terminus of the TACE prodomain that attenuates TACE catalytic activity independently of a cysteine-switch mechanism, which provides new insight into the regulation of TACE enzymatic activity.

Inhibition by TNF-alpha and IL-4 of cationic lipid mediated gene transfer in cystic fibrosis tracheal gland cells

BACKGROUND

In vivo, tracheal gland serous cells highly express the cystic fibrosis transmembrane conductance regulator (cftr) gene. This gene is mutated in the lethal monogenic disease cystic fibrosis (CF). Clinical trials in which the human CFTR cDNA was delivered to the respiratory epithelia of CF patients have resulted in weak and transient gene expression.

METHODS AND RESULTS

As CF is characterized by mucus inspissation, airway infection, and severe inflammation, we tested the hypothesis that inflammation and especially two cytokines involved in the Th1/Th2 inflammatory response, interleukin 4 (IL-4) and TNFalpha, could inhibit gene transfer efficiency using a model of human CF tracheal gland cells (CF-KM4) and Lipofectamine reagent as a transfection reagent. The specific secretory defects of CF-KM4 cells were corrected by Lipofectamine-mediated human CFTR gene transfer. However, this was altered when cells were pre-treated with IL-4 and TNFalpha. Inhibition of luciferase reporter gene expression by IL-4 and TNFalpha pre-treated CF-KM4 cells was measured by activity and real-time RT-PCR. Both cytokines induced similar and synergistic inhibition of transgene expression and activity. This cytokine-mediated inhibition could be prevented by anti-inflammatory agents such as glucocorticoids but not by non-steroidal (NSAI) agents.

CONCLUSIONS

This data suggests that an inflammatory context generated by IL-4 and TNFalpha can inhibit human CFTR gene transfer in CF tracheal gland cells and that glucocorticoids may have a protecting action.

Importance of Tumor Necrosis Factor-α Cleavage Process in Post-Transplantation Lung Injury in Rats

Tumor necrosis factor-alpha (TNF-alpha) has two forms with apparently different biological activities: a membrane-associated form and a soluble form. TNF-alpha-converting enzyme (TACE) mediates a cleavage of membrane-associated TNF-alpha to induce its bioactive soluble form. We hypothesized that inhibition of TACE might prevent TNF-alpha-induced tissue injury while preserving the benefits of TNF-alpha. In this study, we evaluated the role of TACE in acute inflammation using an inhibitor of the enzyme in a rat model of lung transplantation. Inbred Lewis rats underwent left lung isotransplantation, and the donor lungs were kept in Euro-Collins solution with or without the inhibitor. After 6 hours of ischemia, the left lung was transplanted into the recipient rat and reperfused for 4 hours. Inhibition of TACE significantly attenuated endothelial and alveolar septal damage, as assessed by radiolabeled albumin leakage after transplantation. The inhibition also attenuated neutrophil accumulation in the alveolar space and other histopathologic findings, including intercellular adhesion molecule-1 expression. In addition, significantly lower levels of monocyte chemotactic protein-1, cytokine-induced neutrophil chemoattractant-1, high mobility group box-1, and soluble epithelial cadherin and decreased neutrophil elastase activity were observed in bronchoalveolar lavage fluid from the rats treated with the inhibitor. We conclude that TACE mediates a critical step in the development of post-transplantation lung injury.