The central role of Fas-ligand cell signaling in inflammatory lung diseases

The role of inflammation in silicosis

Silicosis is a chronic illness marked by diffuse fibrosis in lung tissue resulting from continuous exposure to SiO2-rich dust in the workplace. The onset and progression of silicosis is a complicated and poorly understood pathological process involving numerous cells and molecules. However, silicosis poses a severe threat to public health in developing countries, where it is the most prevalent occupational disease. There is convincing evidence supporting that innate and adaptive immune cells, as well as their cytokines, play a significant role in the development of silicosis. In this review, we describe the roles of immune cells and cytokines in silicosis, and summarize current knowledge on several important inflammatory signaling pathways associated with the disease, aiming to provide novel targets and strategies for the treatment of silicosis-related inflammation.

Transcriptional Profiling of SARS-CoV-2-Infected Calu-3 Cells Reveals Immune-Related Signaling Pathways

The COVID-19 disease, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), emerged in late 2019 and rapidly spread worldwide, becoming a pandemic that infected millions of people and caused significant deaths. COVID-19 continues to be a major threat, and there is a need to deepen our understanding of the virus and its mechanisms of infection. To study the cellular responses to SARS-CoV-2 infection, we performed an RNA sequencing of infected vs. uninfected Calu-3 cells. Total RNA was extracted from infected (0.5 MOI) and control Calu-3 cells and converted to cDNA. Sequencing was performed, and the obtained reads were quality-analyzed and pre-processed. Differential expression was assessed with the EdgeR package, and functional enrichment was performed in EnrichR for Gene Ontology, KEGG pathways, and WikiPathways. A total of 1040 differentially expressed genes were found in infected vs. uninfected Calu-3 cells, of which 695 were up-regulated and 345 were down-regulated. Functional enrichment analyses revealed the predominant up-regulation of genes related to innate immune response, response to virus, inflammation, cell proliferation, and apoptosis. These transcriptional changes following SARS-CoV-2 infection may reflect a cellular response to the infection and help to elucidate COVID-19 pathogenesis, in addition to revealing potential biomarkers and drug targets.

Innovative Pre-Clinical Data Using Peptides to Intervene in the Evolution of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, relentless, and deadly disease. Little is known about its pathogenetic mechanisms; therefore, developing efficient pharmacological therapies is challenging. This work aimed to apply a therapeutic alternative using immunomodulatory peptides in a chronic pulmonary fibrosis murine model. BALB/c mice were intratracheally instilled with bleomycin (BLM) and followed for 30 days. The mice were treated with the immune modulatory peptides ToAP3 and ToAP4 every three days, starting on the 5th day post-BLM instillation. ELISA, qPCR, morphology, and respiratory function analyses were performed. The treatment with both peptides delayed the inflammatory process observed in the non-treated group, which showed a fibrotic process with alterations in the production of collagen I, III, and IV that were associated with significant alterations in their ventilatory mechanics. The ToAP3 and ToAP4 treatments, by lung gene modulation patterns, indicated that distinct mechanisms determine the action of peptides. Both peptides controlled the experimental IPF, maintaining the tissue characteristics and standard function properties and regulating fibrotic-associated cytokine production. Data obtained in this work show that the immune response regulation by ToAP3 and ToAP4 can control the alterations that cause the fibrotic process after BLM instillation, making both peptides potential therapeutic alternatives and/or adjuvants for IPF.

Nicotinamide Mononucleotide Attenuates LPS-Induced Acute Lung Injury With Anti-Inflammatory, Anti-Oxidative and Anti-Apoptotic Effects

INTRODUCTION

Nicotinamide mononucleotide (NMN) is a nucleotide that is commonly recognized for its role as an intermediate of nicotinamide adenine dinucleotide (NAD⁺) biosynthesis with multiple pharmacological effects. The purpose of this study was to evaluate the protective effect of nicotinamide mononucleotide (NMN) against lipopolysaccharide (LPS)-induced acute lung injury (ALI).

METHODS

We investigated the effect of NMN on ALI-induced inflammatory response, oxidative stress, and cell apoptosis. The ALI mouse model was performed by injecting LPS intratracheally at a dose of 10 mg/kg in 50 μL saline. Flow cytometry was used to detect neutrophil infiltration in bronchoalveolar lavage fluid (BALF), and ELISA was used to detect the contents of inflammatory cytokines TNF-α, IL-1β and IL-6 in BALF. Oxidative stress was evaluated by determining the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in lung tissue. ROS formation was analyzed by immunofluorescence. Western blotting was performed to detect apoptotic levels and p38MAPK/NF-κB phosphorylation levels in lung tissue.

RESULTS

In the ALI mouse model, NMN showed a significant therapeutic effect compared to the LPS group. NMN attenuated the pathological damage and cell apoptosis in lung tissue, decreased the levels of TNF-α, IL-1β, and IL-6 in BALF, and reduced the number of total cells and neutrophils in BALF. In addition, NMN attenuated the LPS-induced elevation of dry-to-wet ratio, MDA content, p38 MAPK and p65 NF-κB phosphorylation levels, and the SOD activity was increased by NMN treatment.

CONCLUSIONS

In conclusion, the present study showed that NMN exerted a protective effect on LPS-induced ALI with anti-inflammatory, antioxidative, and antiapoptotic effects.

Human Cytomegalovirus and Human Herpesvirus 6 Coinfection of Dermal Fibroblasts Enhances the Pro-Inflammatory Pathway Predisposing to Fibrosis: The Possible Impact on Systemic Sclerosis

Systemic sclerosis (SSc) is a severe autoimmune disease likely triggered by genetic and environmental factors, including viral infections. Human cytomegalovirus (HCMV) and human herpesvirus 6A species (HHV-6A) have been associated with SSc, based on in vivo and in vitro evidence, but the data are still inconclusive. Furthermore, despite both viruses being highly prevalent in humans and able to exacerbate each other’s effects, no data are available on their joint effects. Hence, we aimed to study their simultaneous impact on the expression of cell factors correlated with fibrosis and apoptosis in in vitro coinfected fibroblasts, representing the main target cell type in SSc. The results, obtained by a microarray detecting 84 fibrosis/apoptosis-associated factors, indicated that coinfected cells underwent higher and more sustained expression of fibrosis-associated parameters compared with single-infected cells. Thus, the data, for the first time, suggest that HCMV and HHV-6A may cooperate in inducing alterations potentially leading to cell fibrosis, thus further supporting their joint role in SSc. However, further work is required to definitively answer whether β-herpesviruses are causally linked to the disease and to enable the possible use of targeted antiviral treatments to improve clinical outcomes.

Roles of extra-cellular signal-regulated protein kinase 5 signaling pathway in the development of spinal cord injury

Background:

In consideration of characteristics and functions, extra-cellular signal-regulated protein kinase 5 (ERK5) signaling pathway could be a new target for spinal cord injury (SCI) treatment. Our study aimed to evaluate the roles of ERK5 signaling pathway in secondary damage of SCI.

Methods:

We randomly divided 70 healthy Wistar rats into five groups: ten in the blank group, 15 in the sham surgery + BIX02188 (sham + B) group, 15 in the sham surgery + dimethyl sulfoxide (DMSO; sham + D) group, 15 in the SCI + BIX02188 (SCI + B) group, and 15 in the SCI + DMSO (SCI + D) group. BIX02188 is a specific inhibitor of the ERK5 signaling pathway. SCI was induced by the application of vascular clips (with the force of 30 g) to the dura on T10 level, while rats in the sham surgery group underwent only T9-T11 laminectomy. BIX02188 or DMSO was intra-thecally injected at 1, 6, and 12 h after surgery or SCI. Spinal cord samples were taken for testing at 24 h after surgery or SCI.

Results:

Expression of phosphorylated-ERK5 (p-ERK5) significantly increased after SCI. Application of BIX02188 indeed inhibited ERK5 signaling pathway and reduced the degree of spinal cord tissue injury, neutrophil infiltration and proinflammatory cytokine expression, nuclear factor-κB (NF-κB) activation and apoptosis (measured by TdT-mediated 2′-deoxyuridine 5′-triphosphate nick-end labeling, expression of Fas-ligand, BCL2-associated X [Bax], and B-cell lymphoma-2 [Bcl-2]). Double immunofluorescence revealed activation of ERK5 in neurons and microglia after SCI.

Conclusion:

ERK5 signaling pathway was activated in spinal neurons and microglia, contributing to secondary injury of SCI. Moreover, inhibition of ERK5 signaling pathway could alleviate the degree of SCI, which might be related to its regulation of infiltration of inflammatory cells and release of inflammatory cytokines, expression of NF-κB and cell apoptosis.

MicroRNA-27a alleviates LPS-induced acute lung injury in mice via inhibiting inflammation and apoptosis through modulating TLR4/MyD88/NF-κB pathway

Acute lung injury (ALI) is a critical clinical condition with a high mortality rate, characterized with excessive uncontrolled inflammation and apoptosis. Recently, microRNAs (miRNAs) have been found to play crucial roles in the amelioration of various inflammation-induced diseases, including ALI. However, it remains unknown the biological function and regulatory mechanisms of miRNAs in the regulation of inflammation and apoptosis in ALI. The aim of this study is to identify and evaluate the potential role of miRNAs in ALI and reveal the underlying molecular mechanisms of their effects. Here, we analyzed microRNA expression profiles in lung tissues from LPS-challenged mice using miRNA microarray. Because microRNA-27a (miR-27a) was one of the miRNAs being most significantly downregulated, which has an important role in regulation of inflammation, we investigated its function. Overexpression of miR-27a by agomir-27a improved lung injury, as evidenced by the reduced histopathological changes, lung wet/dry (W/D) ratio, lung microvascular permeability and apoptosis in the lung tissues, as well as ameliorative survival of ALI mice. This was accompanied by the alleviating of inflammation, such as the reduced total BALF cell and neutrophil counts, decreased levels of tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-6) interleukin-1β (IL-1β) and myeloperoxidase (MPO) activity in BAL fluid. Toll-like receptor 4 (TLR4), an important regulator of the nuclear factor kappa-B (NF-κB) signaling pathway, was identified as a novel target of miR-27a in RAW264.7 cells. Furthermore, our results showed that LPS stimulation increased the expression of MyD88 and NF-κB p65 (p-p65), but inhibited the expression of inhibitor of nuclear factor-κB-α (IκB-α), suggesting the activation of NF-κB signaling pathway. Further investigations revealed that agomir-miR-27a reversed the promoting effect of LPS on NF-κB signaling pathway. The results here suggested that miR-27a alleviates LPS-induced ALI in mice via reducing inflammation and apoptosis through blocking TLR4/MyD88/NF-κB activation.

The anesthetic agent sevoflurane attenuates pulmonary acute lung injury by modulating apoptotic pathways

The objective of this study was to evaluate lung protection by the volatile anesthetic sevoflurane (SEVO), which inhibits apoptosis. Male Sprague-Dawley rats (250–280 g; n=18) were randomly divided into three groups. The LPS group received 5 mg/kg endotoxin (lipopolysaccharide), which induced acute lung injury (ALI). The control (CTRL) group received normal saline and the SEVO group received sevoflurane (2.5%) for 30 min after ALI was induced by 5 mg/kg LPS. Samples were collected for analysis 12 h after LPS. Lung injury was assessed by pathological observations and tissue wet to dry weight (W/D) ratios. Apoptotic index (AI) was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and electron microscopy. Caspase-3 and cleaved-caspase-3 protein levels were determined by immunocytochemistry and western blotting, respectively. Bcl-xl levels were measured by western blotting and Bcl-2 levels by quantitative real-time polymerase chain reaction and western blotting. In the LPS group, W/D ratios, AI values, caspase-3 and cleaved-caspase-3 levels were significantly higher than in the CTRL group and lung injury was more severe. In the SEVO group, W/D ratios, AI, caspase-3 and cleaved-caspase-3 were lower than in the LPS group. Bcl-2 and Bcl-xl expression were higher than in the LPS group and lung injury was attenuated. Sevoflurane inhalation protected the lungs from injury by regulating caspase-3 activation and Bcl-xl and Bcl-2 expression to inhibit excessive cell apoptosis, and such apoptosis might be important in the pathogenesis of LPS-induced ALI.

Alterations of Fas and Fas-Related Molecules in Patients with Silicosis

Persons with silicosis have not only respiratory disorders but also autoimmune diseases. To clarify the mechanisms involved in the dysregulation of autoimmunity found in patients with silicosis, we have been focusing on Fas and Fas-related molecules in the Fas-mediated apoptotic pathway, because Fas is one of the most important molecules regulating autoimmunity involving T cells. Our findings showed that patients with silicosis exhibited elevated serum soluble Fas levels, an increased relative expression of the soluble fas and dcr3 genes in peripheral blood mononuclear cells, high levels of other variant messages of the fas transcript, relatively decreased expression of genes encoding several physiological inhibitors (such as survivin and toso), and dominancy of lower-membrane Fas expressers in lymphocytes, which transcribe soluble fas dominantly, compared with soluble fas transcription in healthy donors. These findings are consistent with known features regarding immunological factors, such as serum immunogulobulin G levels and the titer of anti-nuclear autoantibodies in silicosis. In addition, anti-caspase 8 autoantibody and anti-Fas autoantibody were detected in serum specimens from patients with silicosis, and a functional assay showed that anti-Fas antibody stimulated Fas-mediated apoptosis. We hypothesize that there are two subpopulations of silicosis lymphocytes. One is a long-term surviving fraction that includes self-recognizing clones showing lower levels of membrane Fas and inhibition of Fas/Fas ligand binding in extracellular spaces. The other subpopulation exhibits apoptosis caused by silica and silicates, is recruited from bone marrow, shows higher levels of membrane Fas, and is sensitive to anti-Fas autoantibody. Further investigation should be performed to confirm the effects of silica and silicates on the human immune system.

Dendritic cell-elicited B-cell activation fosters immune privilege via IL-10 signals in hepatocellular carcinoma

B cells are prominent components of human solid tumours, but activation status and functions of these cells in human cancers remain elusive. Here we establish that over 50% B cells in hepatocellular carcinoma (HCC) exhibit an FcγRII^low/− activated phenotype, and high infiltration of these cells positively correlates with cancer progression. Environmental semimature dendritic cells, but not macrophages, can operate in a CD95L-dependent pathway to generate FcγRII^low/− activated B cells. Early activation of monocytes in cancer environments is critical for the generation of semimature dendritic cells and subsequent FcγRII^low/− activated B cells. More importantly, the activated FcγRII^low/− B cells from HCC tumours, but not the resting FcγRII^high B cells, without external stimulation suppress autologous tumour-specific cytotoxic T-cell immunity via IL-10 signals. Collectively, generation of FcγRII^low/− activated B cells may represent a mechanism by which the immune activation is linked to immune tolerance in the tumour milieu.

Activation and biological function of B cells in cancer are still unclear. Here, the authors show that hepatocarcinoma cells drive the formation of semimature dendritic cells that in turn activate FcγRII^low/− tumour B cells through the CD95L/CD95 axis, leading to the production of IL-10 and suppression of CD8 T cells.

Annexin A5 promotes macrophage activation and contributes to pulmonary fibrosis induced by silica particles

OBJECTIVE

To investigate the contributions and underlying molecular mechanisms of annexin A5 toward silica-induced pulmonary fibrosis.

METHODS

Male C57BL/6 mice were randomly divided into three groups and instilled intratracheally with silica, saline, or air. Mice were euthanized at 3, 7, 14, or 28 days following treatment. Annexin A5 levels in serum and lung tissues were detected by enzyme-linked immunosorbant assay (ELISA) assays or Western blots. The association of annexin A5 levels with silica-induced lung fibrosis was further investigated in the macrophage cell line, RAW264.7. Following exposure of these cells to silica at a concentration of 200 μg/ml for 6 or 12 h, the expression levels of transforming growth factor β1 (TGF-β1), interleukin 1α (IL-1α), Fas ligand (FasL), and their downstream targets were evaluated by Western blots. Furthermore, annexin A5 and FasL were knocked down by small interfering ribonucleic acid (siRNA) and TGF-β1 secretion into the cell culture medium was measured by ELISA assays or Western blots.

RESULTS

Mice treated with silica demonstrated lung fibrosis at 28 days following exposure, whereas, in controls, only mild and transient inflammation was evident at day 3 and day 7 postinstillation and was not present at day 14. Furthermore, silica-exposed mice exhibited significantly (p < 0.05) elevated levels of annexin A5 in serum and lung tissues, relative to control groups. Consistent with these findings, silica exposure of RAW264.7 cells for 6 or 12 h, led to an annexin A5-dependent increase in the expression levels of TGF-β1, IL-1α, FasL, and their downstream target molecules. These silica-induced changes were reversed by siRNA-mediated knockdown of annexin A5, but downregulation of FasL led to increased annexin A5 expression and reduced levels of TGF-β1, IL-1α, and FasL downstream target molecules.

CONCLUSIONS

These findings define a role of annexin A5 in promoting macrophage activation via Fas/FasL pathways in silica-induced lung fibrosis.

Human-specific bacterial pore-forming toxins induce programmed necrosis in erythrocytes

A subgroup of the cholesterol-dependent cytolysin (CDC) family of pore-forming toxins (PFTs) has an unusually narrow host range due to a requirement for binding to human CD59 (hCD59), a glycosylphosphatidylinositol (GPI)-linked complement regulatory molecule. hCD59-specific CDCs are produced by several organisms that inhabit human mucosal surfaces and can act as pathogens, including Gardnerella vaginalis and Streptococcus intermedius. The consequences and potential selective advantages of such PFT host limitation have remained unknown. Here, we demonstrate that, in addition to species restriction, PFT ligation of hCD59 triggers a previously unrecognized pathway for programmed necrosis in primary erythrocytes (red blood cells [RBCs]) from humans and transgenic mice expressing hCD59. Because they lack nuclei and mitochondria, RBCs have typically been thought to possess limited capacity to undergo programmed cell death. RBC programmed necrosis shares key molecular factors with nucleated cell necroptosis, including dependence on Fas/FasL signaling and RIP1 phosphorylation, necrosome assembly, and restriction by caspase-8. Death due to programmed necrosis in RBCs is executed by acid sphingomyelinase-dependent ceramide formation, NADPH oxidase- and iron-dependent reactive oxygen species formation, and glycolytic formation of advanced glycation end products. Bacterial PFTs that are hCD59 independent do not induce RBC programmed necrosis. RBC programmed necrosis is biochemically distinct from eryptosis, the only other known programmed cell death pathway in mature RBCs. Importantly, RBC programmed necrosis enhances the growth of PFT-producing pathogens during exposure to primary RBCs, consistent with a role for such signaling in microbial growth and pathogenesis.

IMPORTANCE

In this work, we provide the first description of a new form of programmed cell death in erythrocytes (RBCs) that occurs as a consequence of cellular attack by human-specific bacterial toxins. By defining a new RBC death pathway that shares important components with necroptosis, a programmed necrosis module that occurs in nucleated cells, these findings expand our understanding of RBC biology and RBC-pathogen interactions. In addition, our work provides a link between cholesterol-dependent cytolysin (CDC) host restriction and promotion of bacterial growth in the presence of RBCs, which may provide a selective advantage to human-associated bacterial strains that elaborate such toxins and a potential explanation for the narrowing of host range observed in this toxin family.

Differential regulation of inflammation and apoptosis in Fas-resistant hepatocyte-specific Bid-deficient mice

BACKGROUND & AIMS

Activation of Fas death receptor results in apoptosis in multiple organs, particularly liver, in a process dependent on Bid cleavage. Mice injected with an anti-Fas antibody die within hours of acute liver failure associated with massive apoptosis and hemorrhage. Our aim was to investigate the crosstalk of apoptotic and inflammatory pathways and the contribution of selective hepatocellular apoptosis during in vivo Fas activation.

METHODS

We generated hepatocyte-specific Bid deficient mice (hBid(-/-)). Acute liver injury was induced by Fas-activating antibody (Jo2) in a time-course study.

RESULTS

In contrast to controls, nearly all Jo2 injected hBid(-/-) survived. Their livers showed complete protection against hepatocellular apoptosis with minimal focal hemorrhagic changes and mainly non-parenchymal cell apoptosis. In agreement, the hepatocytes had no mitochondrial cytochrome c release in cytosol, or caspase 3 activation. hBid(-/-) livers showed marked increase in acute inflammatory foci composed of neutrophils and monocytes associated with the increased expression of proinflammatory chemokines and cytokines, in the manner dependent on non-canonical interleukin-1β activation and amplified in the absence of caspase-3 activation. In addition, hBid(-/-) mice were completely protected from hepatotoxicity and the infiltrated cells were cleared 2 weeks post single Jo2 injection.

CONCLUSIONS

Hepatocyte Bid suppression is critical for the resistance to the lethal effects of Fas activation in vivo. Fas signaling induces differential activation of non-canonical interleukin-1β maturation, amplified in the absence of apoptotic Bid-mitochondrial loop, in hepatocytes. These findings may have important pathophysiological and therapeutic implications in a variety of liver disorders associated with Fas activation.

Peiminine ameliorates bleomycin-induced acute lung injury in rats

The aim of this study was to investigate whether or not peiminine inhibits lung inflammation and pulmonary fibrosis in a rat model of bleomycin-induced lung injury. Rats were randomly divided into 4 groups. In 3 groups, intratracheal bleomycin (5 mg/kg) was used to induce acute lung injury, followed by administration of either carboxymethyl cellulose (control group, n=14), dexamethasone (DXS group, n=14) or peiminine (peiminine group, n=10). In the fourth group (sham-operated, n=12), normal saline was instilled instead of bleomycin, followed by administration of carboxymethyl cellulose. Drugs were administered intragastrically for 28 days. Lung sections were stained with hematoxylin and eosin (H&E) and Masson's trichrome, to grade the degree of alveolitis and pulmonary fibrosis. The lung index was calculated as the ratio of lung to body weight. Serum levels of interleukin-4 (IL-4), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were obtained using a radioimmunoassay. Immunocytochemical methods were employed to assess the expression of transforming growth factor-β (TGF-β), connective tissue growth factor (CTGF), NF-κB, extracellular signal-related kinase (ERK1/2), Fas and FasL in lung tissue. Peiminine and DXS significantly reduced alveolar inflammation and pulmonary interstitial inflammation in rats with bleomycin-induced lung injury. These protective effects were associated with significant (P<0.05) decreases in the levels of IFN-γ in serum and of TGF-β, CTGF, ERK1/2, NF-κB and FasL in lung tissue. No effects were observed on serum TNF-α or IL-4. In conclusion, peiminine inhibits lung inflammation and pulmonary fibrosis in a rat model of bleomycin-induced lung injury, by reducing circulating IFN-γ levels and inhibiting signal transduction pathways involving TGF-β, CTGF, ERK1/2, NF-κB and FasL.

The effect of infection order of porcine circovirus type 2 and porcine reproductive and respiratory syndrome virus on dually infected swine alveolar macrophages

Background

Concurrent infection with porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) is known as one of the major causes for porcine respiratory disease complex (PRDC). Dual infection with PCV2 and PRRSV is consistently to have more severe clinical presentations and pulmonary lesions than infection with PCV2 alone or PRRSV alone. However, it is not known if dual infections with PCV2 and PRRSV in different infection order may lead to different clinical symptoms in the host. To mimic the possible field conditions, swine alveolar macrophages (AMs) were inoculated with PCV2 and PRRSV in vitro simultaneously or with one virus 18 h earlier than the other. The cell viability, cytopathic effects, antigen-containing rates, phagocytotic and microbial killing capabilities, cytokine profiles (IL-8, TNF-α, and IFN-α) and FasL transcripts were determined, analyzed, and compared to prove the hypothesis.

Results

A marked reduction in PRRSV antigen-containing rate, cytopathic effect, and TNF-α expression level was revealed in AMs inoculated with PCV2 and PRRSV simultaneously and in AMs inoculated with PCV2 first then PRRSV 18 h later, but not in AMs inoculated with PRRSV first then PCV2 18 h later. Transient decrease in phagocytosis but constant reduction in microbicidal capability in AMs in the group inoculated with PCV2 alone and constant decrease in phagocytosis and microbicidal capability in AMs in all PRRSV-inoculated groups were noted. The levels of IL-8, TNF-α, IFN-α, and FasL transcripts in AMs in all groups with dual inoculation of PCV2 and PRRSV were significantly increased regardless of the infection orders as compared with infection by PCV2 alone or PRRSV alone.

Conclusions

Swine AMs infected with PCV2 first then PRRSV later or infected with PCV2 and PRRSV simultaneously displayed marked reduction in PRRSV antigen-containing rate, cytopathic effect, and TNF-α expression level. The different inoculation orders of PCV2 and PRRSV in AMs leading to different results in viral antigen positivity, cytopathology, and cytokine profile may explain, at least partially, the underlying mechanism of the enhanced pulmonary lesions in PRDC exerted by dual infection with PCV2 and PRRSV and the variable clinical manifestations of PRDC-affected pigs in the field.

Effect of fasudil, a selective inhibitor of Rho kinase activity, in the secondary injury associated with the experimental model of spinal cord trauma

Rho kinase (ROK) may play an important role in regulating the biological events of cells, including proliferation, differentiation, and survival/death. Blockade of ROK promotes axonal regeneration and neuron survival in vivo and in vitro, thereby exhibiting potential clinical applications in spinal cord damage and stroke. The aim of this experimental study was to determine the role of ROK signaling pathways in the inflammatory response, in particular in the secondary injury associated with the experimental model of spinal cord trauma. The injury was induced by application of vascular clips to the dura via a four-level T5 to T8 laminectomy in mice. Fasudil was administered in mice (10 mg/kg i.p.) 1 and 6 h after the trauma. The treatment with fasudil significantly decreased 1) histological damage; 2) motor recovery; 3) nuclear factor-κB (NF-κB) expression; 4) ROK activity; 5) inflammasome activation (caspase-1 and NOD-like receptor family, pyrin domain-containing 3 expression); 6) production of proinflammatory cytokine such as tumor necrosis factor and interleukin-1β (IL-1β); 7) neutrophil infiltration; 8) nitrotyrosine and poly-ADP-ribose formation; 9) glial fibrillary acidic protein expression; 10) apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, FAS ligand expression, and Bax and Bcl-2 expression); and 11) mitogen-activated protein kinase activation (phospho-extracellular signal-regulated kinase and phospho-c-Jun NH(2)-terminal kinase expression). Our results indicate that inhibition of ROK by fasudil may represent a useful therapeutic perspective in the treatment of inflammation associated with spinal cord trauma.

Anti-inflammatory effect of simvastatin in an experimental model of spinal cord trauma: involvement of PPAR-α

BACKGROUND

Statins such as simvastatin are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase used in the prevention of cardiovascular disease. In addition to their cholesterol-lowering activities, statins exert pleiotropic anti-inflammatory effects, which might contribute to their beneficial effects on lipid-unrelated inflammatory diseases. Recently it has been demonstrated that the peroxisome proliferator-activated receptor (PPAR)-α mediates anti-inflammatory effects of simvastatin in vivo models of acute inflammation. Moreover, previous results suggest that PPAR-α plays a role in control of secondary inflammatory process associated with spinal cord injury (SCI).

METHODS

With the aim to characterize the role of PPAR-α in simvastatin activity, we tested the efficacy of simvastatin (10 mg/kg dissolved in saline i.p. 1 h and 6 h after the trauma) in an experimental model of SCI induced in mice by extradural compression of the spinal cord (T6-T7 level) using an aneurysm clip with a closing force of 24 g via a four-level T5-T8 laminectomy, and comparing mice lacking PPAR-α (PPAR-α KO) with wild type (WT) mice. In order to elucidate whether the effects of simvastatin are due to activation of the PPAR-α, we also investigated the effect of a PPAR-α antagonist, GW6471 (1 mg/kg administered i.p. 30 min prior treatment with simvastatin) on the protective effects of on simvastatin.

RESULTS

Results indicate that simvastatin activity is weakened in PPAR-α KO mice, as compared to WT controls. In particular, simvastatin was less effective in PPAR-α KO, compared to WT mice, as evaluated by inhibition of the degree of spinal cord inflammation, neutrophil infiltration, nitrotyrosine formation, pro-inflammmatory cytokine expression, nuclear factor (NF)-κB activation, inducible nitric-oxide synthase (iNOS) expression, and apoptosis. In addition we demonstrated that GW6471 significantly antagonized the effect of the statin and thus abolished the protective effect.

CONCLUSIONS

This study indicates that PPAR-α can contribute to the anti-inflammatory activity of simvastatin in SCI.

Targeted mutation of Fas ligand gene attenuates brain inflammation in experimental stroke

Inflammation is an important contributing mechanism in ischemic brain injury. The current study elucidates a previously unexplored role of Fas ligand (FasL) in post-stroke inflammatory responses that is independent of its well-known effect in triggering apoptosis. Focal cerebral ischemia was induced for 2 h by right middle cerebral artery occlusion (MCAO) in FasL mutant (gld) and wild-type mice. FasL mutation profoundly reduced brain damage and improved neurological performance from 6 to 72 h after ischemic stroke. The production of inflammatory cytokines in the brain was attenuated in gld mice after ischemia in the absence of dramatic change in inflammatory cell apoptosis. FasL mutation attenuated the recruitment of peripheral inflammatory cells (neutrophil) and inhibited the activation of residential glial cells (microglia and astrocyte). FasL mutation reduced CD8(+) T cells and turned the Th1/Th2 balance towards Th2 in the brain and peripheral blood after cerebral ischemia. In contrast to cerebral ischemia, the molecular and cellular inflammatory changes induced by intracerebroventricular injection of lipopolysaccharide (LPS) were also attenuated in gld mice. Moreover, the soluble FasL (sFasL) and phospho-SAPK/JNK were decreased in gld mice, suggesting that the inflammatory role of FasL in experimental stroke might relate to sFasL and the c-Jun N-terminal kinase (JNK) signaling pathway. Taken together, our data suggest a novel role of FasL in the damaging inflammatory responses associated with cerebral ischemia. Neutralization of FasL may be a novel therapeutic strategy to suppress post-stroke inflammation and improve the long-term outcomes of stroke.

Human FasL gene is a target of β-catenin/T-cell factor pathway and complex FasL haplotypes alter promoter functions

FasL expression on human immune cells and cancer cells plays important roles in immune homeostasis and in cancer development. Our previous study suggests that polymorphisms in the FasL promoter can significantly affect the gene expression in human cells. In addition to the functional FasL SNP -844C>T (rs763110), three other SNPs (SNP -756A>G or rs2021837, SNP -478A>T or rs41309790, and SNP -205 C>G or rs74124371) exist in the proximal FasL promoter. In the current study, we established three major FasL hyplotypes in humans. Interestingly, a transcription motif search revealed that the FasL promoter possessed two consensus T-cell factor (TCF/LEF1) binding elements (TBEs), which is either polymorphic (SNP -205C>G) or close to the functional SNP -844C>T. Subsequently, we demonstrate that both FasL TBEs formed complexes with the TCF-4 and β-catenin transcription factors in vitro and in vivo. Co-transfection of LEF-1 and β-catenin transcription factors significantly increased FasL promoter activities, suggesting that FasL is a target gene of the β-catenin/T-cell factor pathway. More importantly, we found that the rare allele (-205G) of the polymorphic FasL TBE (SNP -205C>G) failed to bind the TCF-4 transcription factor and that SNP -205 C>G significantly affected the promoter activity. Furthermore, promoter reporter assays revealed that FasL SNP haplotypes influenced promoter activities in human colon cancer cells and in human T cells. Finally, β-catenin knockdown significantly decreased the FasL expression in human SW480 colon cancer cells. Collectively, our data suggest that β-catenin may be involved in FasL gene regulation and that FasL expression is influenced by FasL SNP haplotypes, which may have significant implications in immune response and tumorigenesis.

Control of pathogenic CD4 T cells and lethal immunopathology by signaling immunoadaptor DAP12 during influenza infection

Immunopathology is a major cause of influenza-associated morbidity and mortality worldwide. However, the role and regulatory mechanisms of CD4 T cells in severe lung immunopathology following acute influenza infection are poorly understood. In this paper, we report that the emergence of immunopathogenic CD4 T cells is under the control of a transmembrane immunoadaptor DAP12 pathway during influenza infection. We find that the mice lacking DAP12 have unaltered viral clearance but easily succumb to influenza infection as a result of uncontrolled immunopathology. Such immunopathology is associated with markedly increased CD4 T cells displaying markedly increased cytotoxicity and Fas ligand expression. Furthermore, the immunopathogenic property of these CD4 T cells is transferrable. Thus, depletion of CD4 T cells or abrogation of Fas/Fas ligand signaling pathway improves survival and immunopathology. We further find that DAP12 expressed by dendritic cells plays an important role in controlling the immunopathogenic CD4 T cells during influenza infection. Our findings identify a novel pathway that controls the level of immune-pathogenic CD4 T cells during acute influenza infection.

An overview of caspase: Apoptotic protein for silicosis

Silicosis is a chronic lung disease characterized by granulomatous and fibrotic lesions, which occurs due to accumulation of respirable silica mineral particles. Apoptosis is an important phenomenon of cell death in silicosis. The relationship between silica dust and its exposure is well established. But, the complex chain of cellular responses, which leads to caspase activation in silicosis, has not been fully discovered. Caspase activation plays a central role in the execution of apoptosis. Silica-induced apoptosis of the alveolar macrophages could potentially favor a proinflammatory state, occurring in the lungs of silicotic patients, resulting in the activation of caspase prior to induction of the intrinsic and extrinsic apoptosis pathways. Recent studies indicated that apoptosis may involve in pulmonary disorders. This review summarizes the current knowledge about the underling mechanism of biochemical pathways in caspase activation that have been ignored so far in silicosis. In addition, caspase could be a key apoptotic protein that can be used as an effective biomarker for the study of occupational diseases. It may provide an important link in understanding the molecular mechanisms of silica-induced lung pathogenesis.

Pulmonary lesions and serum levels of soluble Fas (sCD95) in former hard coal miners

Objective

Fas/APO-1 (CD95) and Fas Ligand (FasL) is a major mediator system that activates programmed cell death (apoptosis) and is most important for pulmonary cellular homeostasis. Another form of Fas, circulating soluble Fas (sCD95), produced by alternative mRNA splicing antagonizes the cell-surface Fas function. It was the aim of the study to test the hypothesis that the Fas/FasL system is implicated in the development of silica-induced pulmonary nodular lesions.

Materials and methods

We investigated the serum levels of sCD95 in 55 former hard coal miners. Coal workers' pneumoconiosis (CWP) was assumed when the profusion of small round opacities according to the ILO 2000 classification system was 1/1 or greater. Analyses of sCD95 were performed by a sandwich ELISA.

Results

Radiologic CWP was found in 34 of the 55 individuals. The age of subjects with and without CWP was similar (73.5 (SD 7.2) years vs. 73.5 (7.1) years; P = 0.924). sCD95 could be quantified in all samples; significantly higher levels were observed in subjects with radiologic signs of CWP (914 (752-1251) pg/ml vs. 632 (509-804) pg/ml, P < 0.001). However, there was no relationship between sCD95 serum concentrations and the quantity of profusion according to ILO.

Conclusions

The hypothesis of elevated sCD95 concentrations in CWP was corroborated. The usefulness of sCD95 for prevention and diagnosis of CWP and other forms of silica-induced fibrosis needs to be established By epidemiological studies.

Aerosol therapy for the treatment of osteosarcoma lung metastases: targeting the Fas/FasL pathway and rationale for the use of gemcitabine

Lung metastases are the main cause of death in patients with osteosarcoma (OS). Salvage chemotherapy has been largely unsuccessful in improving the long-term survival of these patients. Understanding the mechanisms that play a role in the metastatic process may identify new therapeutic strategies. We have demonstrated that the cell surface Fas expression, the Fas/FasL signaling pathway, and the constitutive expression of FasL in the lung microenvironment play a critical role in the metastatic potential of OS cells. Here we review the status of Fas expression in two sets of OS cells, human SAOS and LM7 and murine K7 and K7M2, which differ in their ability to metastasize to the lungs. We demonstrated that Fas expression inversely correlated with metastatic potential. Evaluation of Fas expression in a set of lung metastases from patients demonstrated low or no Fas expression consistent with our hypothesis that Fas+ osteosarcoma cells cannot form metastases. The absence of FasL in the lung allows Fas+ osteosarcoma cells to form metastases indicating that the microenvironment is an important contributor to the metastatic potential of osteosarcoma cells. Disruption of the signal transduction pathway using Fas-associated death domain dominant negative (FDN) also allowed Fas+ cells to form lung metastases. Aerosol Gemcitabine (GCB) upregulated Fas expression and induced tumor regression in wild-type Balb/c mice but not Fas L-deficient mice. In conclusion, Fas constitutes an early defense mechanism that allows Fas+ tumor cells to undergo apoptosis when in contact with constitutive FasL in the lung. Fas- cells or cells with a corrupted Fas pathway evade this defense mechanism and form lung metastases. The aerosol delivery of chemotherapeutic agents that upregulate Fas expression may benefit patients with established pulmonary metastases.

Effect of Apocynin, an inhibitor of NADPH oxidase, in the inflammatory process induced by an experimental model of spinal cord injury

NADPH-oxidase is an enzyme responsible for reactive oxygen species production, and inhibition of this enzyme represents an attractive therapeutic target for the treatment of many diseases. The aim of this study was to investigate the effects of Apocynin, NADPH-oxidase inhibitor, in the modulation of secondary injury in the spinal cord. The injury was induced by application of vascular clips to the dura via a four-level T5-T8 laminectomy in mice. Treatment with Apocynin 1 and 6 h after the trauma significantly decreased (1) the degree of spinal cord inflammation and tissue injury, (2) neutrophil infiltration, (3) adhesion molecule expression, (4) nuclear transcription factor-κB expression, (5) nitrotyrosine and poly-ADP-ribose formation, (6) pro-inflammatory cytokines production, (7) apoptosis and (8) mitogen-activated protein kinase activation. Moreover, Apocynin significantly ameliorated the loss of limb function (evaluated by motor recovery score). Thus, it is proposed that Apocynin may be useful in the treatment of inflammation associated with spinal cord trauma.

Calcium and ER stress mediate hepatic apoptosis after burn injury

A hallmark of the disease state following severe burn injury is decreased liver function, which results in gross metabolic derangements that compromise patient survival. The underlying mechanisms leading to hepatocyte dysfunction after burn are essentially unknown. The aim of the present study was to determine the underlying mechanisms leading to hepatocyte dysfunction and apoptosis after burn. Rats were randomized to either control (no burn) or burn (60% total body surface area burn) and sacrificed at various time-points. Liver was either perfused to isolate primary rat hepatocytes, which were used for in vitro calcium imaging, or liver was harvested and processed for immunohistology, transmission electron microscopy, mitochondrial isolation, mass spectroscopy or Western blotting to determine the hepatic response to burn injury in vivo. We found that thermal injury leads to severely depleted endoplasmic reticulum (ER) calcium stores and consequent elevated cytosolic calcium concentrations in primary hepatocytes in vitro. Burn-induced ER calcium depletion caused depressed hepatocyte responsiveness to signalling molecules that regulate hepatic homeostasis, such as vasopressin and the purinergic agonist ATP. In vivo, thermal injury resulted in activation of the ER stress response and major alterations in mitochondrial structure and function - effects which may be mediated by increased calcium release by inositol 1,4,5-trisphosphate receptors. Our results reveal that thermal injury leads to dramatic hepatic disturbances in calcium homeostasis and resultant ER stress leading to mitochondrial abnormalities contributing to hepatic dysfunction and apoptosis after burn injury.

Calcium and ER stress mediate hepatic apoptosis after burn injury

A hallmark of the disease state following severe burn injury is decreased liver function, which results in gross metabolic derangements that compromise patient survival. The underlying mechanisms leading to hepatocyte dysfunction after burn are essentially unknown. The aim of the present study was to determine the underlying mechanisms leading to hepatocyte dysfunction and apoptosis after burn. Rats were randomized to either control (no burn) or burn (60% total body surface area burn) and sacrificed at various time-points. Liver was either perfused to isolate primary rat hepatocytes, which were used for in vitro calcium imaging, or liver was harvested and processed for immunohistology, transmission electron microscopy, mitochondrial isolation, mass spectroscopy or Western blotting to determine the hepatic response to burn injury in vivo. We found that thermal injury leads to severely depleted endoplasmic reticulum (ER) calcium stores and consequent elevated cytosolic calcium concentrations in primary hepatocytes in vitro. Burn-induced ER calcium depletion caused depressed hepatocyte responsiveness to signalling molecules that regulate hepatic homeostasis, such as vasopressin and the purinergic agonist ATP. In vivo, thermal injury resulted in activation of the ER stress response and major alterations in mitochondrial structure and function - effects which may be mediated by increased calcium release by inositol 1,4,5-trisphosphate receptors. Our results reveal that thermal injury leads to dramatic hepatic disturbances in calcium homeostasis and resultant ER stress leading to mitochondrial abnormalities contributing to hepatic dysfunction and apoptosis after burn injury.

Liver X receptor agonist treatment regulates inflammatory response after spinal cord trauma

Liver X receptor alpha (LXRalpha) and LXRbeta are members of the nuclear receptor superfamily of ligand-activated transcription factors. The aim of this study was to investigate the effects of T0901317, a potent LXR receptor ligand, in a mouse model of spinal cord injury (SCI). SCI was induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy in mice. Treatment with T0901317, 1 and 6 h after the SCI, significantly decreased (i) the degree of spinal cord inflammation and tissue injury (histological score); (ii) neutrophil infiltration (myeloperoxidase activity); (iii) inducible nitric oxide synthase expression; (iv) nitrotyrosine, lipid peroxidation, and poly-ADP-ribose formation; (v) pro-inflammatory cytokines expression; (vi) nuclear factor-kappa B activation; and (vii) apoptosis (terminal deoxynucleotidyltransferase-mediated UTP end labeling staining, FAS ligand, Bax, and Bcl-2 expression). Moreover, T0901317 significantly ameliorated the loss of limb function (evaluated by motor recovery score). These data suggest that LXR ligand may be useful in the treatment of inflammation associated with SCI.

Fas inhibition attenuates lipopolysaccharide-induced apoptosis and cytokine release of rat type II alveolar epithelial cells

The aim of this study is to investigate whether silencing of Fas could have an influence on type II alveolar epithelial cell (AEC) apoptosis and inflammatory cytokine production, which prevents alveolar healing after acute lung injury (ALI). Rat primary type II AECs were isolated by elastase cell dispersion and IgG panning. The cells were transfected with Fas-specific small interfering RNA (siRNA) followed by treatment with lipopolysaccharide (LPS), Fas ligand (FasL) or both. The effects of siRNA-mediated silencing of Fas on LPS-induced apoptosis and cytokine release were then assessed. Notably, LPS, either alone or together with FasL, significantly stimulated type II AEC apoptosis and the release of tumor necrosis factor-alpha (TNF-α) and monocyte chemoattractant protein 1 (MCP-1) (P < 0.05 versus the control without treatment). Moreover, the effects exerted by both LPS and FasL were considerably counteracted by pretreatment with Fas-siRNA (P < 0.05 versus treatment with LPS and FasL). In conclusion, inhibition of Fas can diminish LPS-induced apoptosis and inflammatory cytokine production in type II AECs, and Fas specific siRNAs may have therapeutic potentials for intervention of ALI/ARDS.

Is the Fas/Fas-L pathway a promising target for treating inflammatory heart disease?

The elucidation of the intricate molecular network of costimulus and regulatory pathways of the immune system led to the design of molecular therapies that specifically inactivate some cellular responses and ameliorate some autoimmune and inflammatory diseases. This innovative concept opens a new class of therapies, and one of the central components that could be targeted in future molecular therapies is the Fas-based pathway. Both soluble and membrane-bound Fas and Fas-L molecules exert a wide range of proinflammatory functions through the secretion of cytokines and chemokines, cellular chemotaxis, transcriptional regulation, cellular death, and others. Accordingly, many chronic inflammatory diseases, including myocarditis, are attenuated in mice lacking either molecule. Although it is tempting to speculate that the Fas/Fas-L pathway could be targeted for in vivo myocarditis therapy, the plurality of Fas/Fas-L functions can be an obstacle, leading to important side effects. In this review, we suggest that the injection of nonagonistic antibodies raised against the Fas molecule or the inactivation of downstream Fas-1,4,5-inositol triphosphate cascade are possible targets for myocarditis treatment.

Fas-mediated apoptosis is regulated by the extracellular matrix protein CCN1 (CYR61) in vitro and in vivo

Although Fas ligand (FasL) is primarily expressed by lymphoid cells, its receptor Fas (CD95/Apo-1) is broadly expressed in numerous nonlymphoid tissues and can mediate apoptosis of parenchymal cells upon injury and infiltration of inflammatory cells. Here we show that CCN1 (CYR61) and CCN2 (CTGF), matricellular proteins upregulated at sites of inflammation and wound repair, synergize with FasL to induce apoptosis by elevating cellular levels of reactive oxygen species (ROS). CCN1 acts through engagement of integrin alpha(6)beta(1) and cell surface heparan sulfate proteoglycans, leading to ROS-dependent hyperactivation of p38 mitogen-activated protein kinase in the presence of FasL to enhance mitochondrial cytochrome c release. We show that CCN1 activates neutral sphingomyelinase, which functions as a key source of CCN1-induced ROS critical for synergism with FasL. Furthermore, Fas-dependent hepatic apoptosis induced by an agonistic monoclonal anti-Fas antibody or intragastric administration of alcohol is severely blunted in knock-in mice expressing an apoptosis-defective Ccn1 allele. These results demonstrate that CCN1 is a physiologic regulator of Fas-mediated apoptosis and that the extracellular matrix microenvironment can modulate Fas-dependent apoptosis through CCN1 expression.

ETANERCEPT REDUCES ACUTE TISSUE INJURY AND MORTALITY ASSOCIATED TO ZYMOSAN-INDUCED MULTIPLE ORGAN DYSFUNCTION SYNDROME

It has been well demonstrated that TNF-alpha is integral to the pathogenesis of multiple organ dysfunction syndrome (MODS). In this study, we investigate the effects of etanercept (10 mg/kg, s.c.), a specific TNF-alpha-soluble inhibitor, on the acute phase and late mortality in a murine model of MODS of nonseptic origin induced by zymosan (500 mg/kg, suspended in saline solution, i.p.). Etanercept was administered 1 h after the injection of zymosan. Animals were killed after 18 h. In another set of experiments, mice were monitored for systemic toxicity, loss of body weight, and mortality for 12 days. Sham-treated and TNF receptor 1 (TNFR1)-deficient animals were used as control. Treatment of mice with Etanercept and TNFR1 gene deletion decreased the peritoneal exudation and the migration of neutrophils caused by zymosan. In addition, pharmacological and genetic neutralization of TNF-alpha attenuated pancreas and ileum injury (histology), the increase in myeloperoxidase activity in the ileum and in the lung, and the formation of TNF-alpha and IL-1beta. Immunohistochemical analysis for TNF-alpha, transforming growth factor beta, and vascular endothelial growth factor revealed a positive staining in pancreas and ileum sections. The degree of immunostaining was markedly reduced after etanercept treatment and in TNFR1 knockout mice. Furthermore, TNF-alpha neutralization decreased the potent apoptotic stimulus induced by zymosan. All of these findings ultimately led to an amelioration of organ functions at 18 h and to a better survival rate at 12 days. Therefore, we demonstrate that etanercept reduces acute tissue injury and mortality associated to MODS of nonseptic origin in mice.

IL-1R1/MyD88 signaling and the inflammasome are essential in pulmonary inflammation and fibrosis in mice

The molecular mechanisms of acute lung injury resulting in inflammation and fibrosis are not well established. Here we investigate the roles of the IL-1 receptor 1 (IL-1R1) and the common adaptor for Toll/IL-1R signal transduction, MyD88, in this process using a murine model of acute pulmonary injury. Bleomycin insult results in expression of neutrophil and lymphocyte chemotactic factors, chronic inflammation, remodeling, and fibrosis. We demonstrate that these end points were attenuated in the lungs of IL-1R1- and MyD88-deficient mice. Further, in bone marrow chimera experiments, bleomycin-induced inflammation required primarily MyD88 signaling from radioresistant resident cells. Exogenous rIL-1beta recapitulated a high degree of bleomycin-induced lung pathology, and specific blockade of IL-1R1 by IL-1 receptor antagonist dramatically reduced bleomycin-induced inflammation. Finally, we found that lung IL-1beta production and inflammation in response to bleomycin required ASC, an inflammasome adaptor molecule. In conclusion, bleomycin-induced lung pathology required the inflammasome and IL-1R1/MyD88 signaling, and IL-1 represented a critical effector of pathology and therapeutic target of chronic lung inflammation and fibrosis.

Evidence for the role of mitogen-activated protein kinase signaling pathways in the development of spinal cord injury

Mitogen-activated protein kinase (MAPK) signaling pathways involve two closely related MAPKs, known as extracellular signal-regulated kinase (ERK)1 and ERK2. The aim of the present study was to evaluate the contribution of MAPK3/MAPK1 in the secondary damage in experimental spinal cord injury (SCI) in mice. To this purpose, we used 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059), which is an inhibitor of MAPK3/MAPK1. Spinal cord trauma was induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy. SCI in mice resulted in severe trauma characterized by edema, neutrophil infiltration, and production of inflammatory mediators, tissue damage, and apoptosis. PD98059 treatment (10 mg/kg i.p.) at 1 and 6 h after the SCI significantly reduced 1) the degree of spinal cord inflammation and tissue injury (histological score), 2) neutrophil infiltration (myeloperoxidase activity), 3) nitrotyrosine formation, 4) proinflammatory cytokines expression, 5) nuclear factor-kappaB activation, 6) phospho-ERK1/2 expression, and 6) apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, Fas ligand, Bax, and Bcl-2 expression). Moreover, PD98059 significantly ameliorated the recovery of limb function (evaluated by motor recovery score) in a dose-dependent manner. Taken together, our results clearly demonstrate that PD98059 treatment reduces the development of inflammation and tissue injury associated with spinal cord trauma.

Glycogen synthase kinase 3beta inhibition reduces the development of nonseptic shock induced by zymosan in mice

Glycogen synthase kinase 3 has recently been identified as a ubiquitous serine-threonine protein kinase that participates in a multitude of cellular processes and plays an important role in the pathophysiology of a number of diseases. In the present study, we have investigated the effects of 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), a glycogen synthase kinase 3beta inhibitor, on the development of nonseptic shock caused by zymosan (dose, 500 mg/kg i.p. suspension in saline) in mice. Organ failure and systemic inflammation in mice was assessed 18 h after administration of zymosan and/or TDZD-8; another group of mice was monitored for 12 days (for clinical score and mortality). Treatment of mice with TDZD-8 (dose, 10 mg/kg i.p., 1 and 6 h after zymosan administration) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan. TDZD-8 also attenuated the lung, liver, and pancreatic injury, the renal dysfunction caused by zymosan, and the increase in myeloperoxidase activity caused by zymosan in the lung and in the intestine. Immunohistochemical analysis for inducible nitric oxide synthase, nitrotyrosine, poly(ADP-ribose), CD30, CD30 ligand, and Fas ligand revealed positive staining in lung and intestinal tissues obtained from zymosan-injected mice. The degree of staining for inducible nitric oxide synthase, nitrotyrosine, poly(ADP-ribose), CD30, CD30 ligand, and Fas ligand were markedly reduced in tissue sections obtained from zymosan-injected mice that had received TDZD-8. This study provides the first evidence that TDZD-8 attenuates the degree of zymosan-induced, nonseptic shock in mice.

Fas ligand-dependent inflammatory regulation in acute myocarditis induced by Trypanosoma cruzi infection

Fas/Fas ligand (Fas-L) engagement, a potent inducer of apoptosis, is also important for cellular activation, regulation of effector and chemotactic activity, and secretion of chemokines and cytokines. We evaluated the relevance of Fas/Fas-L in the regulation of myocarditis induced by Trypanosoma cruzi infection and observed that in Fas-L(-/-) mice (gld/gld), cardiac infiltration was significantly reduced, accordingly showing less cardiomyocyte destruction. Fluorescence-activated cell sorting analysis of cardiac inflammatory cells showed higher numbers of CD8(+) T cells in BALB/c compared with gld/gld mice but similar levels of lymphocyte function-associated antigen-1, intercellular adhesion molecule, CD2, and CD69 expression; MAC-1(+) myeloid cells and mast cells were increased in BALB/c mice, whereas gld/gld mice exhibited an enrichment of CD4(+/low) T cells. Intracellular labeling of cytokines revealed no clear cardiac skewing of Th1 or Th2 responses, but we found a higher number of interleukin-10(+) cells in gld/gld mice and a deficient expression of vascular cell adhesion molecule-1 on cardiac endothelial cells in gld/gld mice. Finally, we found a population of CD3(+) but CD4/CD8 double negative cardiac T cells in both groups of infected mice, but down-regulation of some adhesion molecules and surface receptors was only observed in gld/gld mice, indicating a targeted T-cell population mostly affected by the lack of Fas-L engagement. These results point to a role for myocarditis regulation by Fas/Fas-L beyond its possible direct relevance in cellular death.

Silica-associated systemic lupus erythematosus in an elderly man

The predominantly young woman-orientated systemic lupus erythematosus (SLE) is a disease that involves an extremely complicated and multifactorial interaction of various genetic and environmental factors. Crystalline silica (Si) may act as an immunoadjuvant to increase secretions of inflammatory endogenous substances and antibody production. In addition, previous studies have suggested that exposure to Si may induce SLE. Although the biologic mechanism of Si in SLE is unclear, defective apoptosis leading to the prolonged survival of pathogenic lymphocytes was thought to be one of mechanisms of Si-associated SLE (sSLE). In the present study, a rare case of an elderly man suffering from sSLE responded well to glucocorticoid therapy. The present findings were reviewed with reference to previous literature.

Melatonin modulates signal transduction pathways and apoptosis in experimental colitis

Various evidences have documented that the pineal secretory product melatonin exerts an important anti-inflammatory effect in different experimental models including colitis. The aim of the present study was to evaluate whether melatonin regulates the inflammatory response of experimental colitis in rats at the level of signal transduction pathway. Colitis was induced by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS). Four days after DNBS administration, a substantial increase of colon TNF-alpha production was associated with the colon damage. In DNBS-treated rats, the colon injury correlated with a significant rise of apoptosis (evaluated by TUNEL coloration) which was associated with a significant increased expression of proapoptotic Bax and decreased colon content of antiapoptotic Bcl-2. This inflammatory response was also related to activation of nuclear factor-kappaB (NF-kappaB) and phosphorylation of c-Jun as well as FAS ligand expression in the colon. Treatment with melatonin (15 mg/kg daily i.p.) was associated with a remarkable amelioration of colonic disrupted architecture as well as a significant reduction of TNF-alpha. Melatonin also reduced the NF-kappaB activation and phosphorylation of c-Jun as well as the Fas ligand expression in the colon. Furthermore, melatonin reduced the expression of Bax and prevented the loss of Bcl-2 proteins as well as the presence of apoptotic cells caused by DNBS. The results of this study show that melatonin administration exerts beneficial effects in inflammatory bowel disease by modulating signal transduction pathways.

Cysteine cathepsins and caspases in silicosis

Silicosis is an occupational pneumoconiosis caused by inhalation of crystalline silica. It leads to the formation of fibrohyalin nodes that result in progressive fibrosis. Alternatively, emphysema may occur, with abnormal destruction of collagen fibres in the advanced stages. Although the pathophysiological mechanisms remain unclear, it has been established that the lung responds to silica by massive enrollment of alveolar macrophages, triggering an inflammatory cascade of reactions. An imbalance in the expression of lung proteases and their inhibitors is implicated in extracellular matrix remodelling and basement membrane disruption. Moreover, exposure to silica can initiate apoptotic cell death of macrophages. This review summarises the current knowledge on cysteine cathepsins that have been ignored so far during silicosis and outlines the recent progress on cellular pathways leading to silica-induced caspase activation, which have been partly delineated.