Inflammatory cytokines mediate C-C (monocyte chemotactic protein 1) and C-X-C (interleukin 8) chemokine expression in human pleural fibroblasts

The Aftermath of Surviving Acute Radiation Hematopoietic Syndrome and its Mitigation

Intensive research is underway to find new agents that can successfully mitigate the acute effects of radiation exposure. This is primarily in response to potential counterthreats of radiological terrorism and nuclear accidents but there is some hope that they might also be of value for cancer patients treated with radiation therapy. Research into mitigation countermeasures typically employs classic animal models of acute radiation syndromes (ARS) that develop after whole-body irradiation (WBI). While agents are available that successfully mitigate ARS when given after radiation exposure, their success raises questions as to whether they simply delay lethality or unmask potentially lethal radiation pathologies that may appear later in time. Life shortening is a well-known consequence of WBI in humans and experimental animals, but it is not often examined in a mitigation setting and its causes, other than cancer, are not well-defined. This is in large part because delayed effects of acute radiation exposure (DEARE) do not follow the strict time-dose phenomena associated with ARS and present as a diverse range of symptoms and pathologies with low mortality rates that can be evaluated only with the use of large cohorts of subjects, as in this study. Here, we describe chronically increased mortality rates up to 660 days in large numbers of mice given LD_70/30 doses of WBI. Systemic myeloid cell activation after WBI persists in some mice and is associated with late immunophenotypic changes and hematopoietic imbalance. Histopathological changes are largely of a chronic inflammatory nature and variable incidence, as are the clinical symptoms, including late diarrhea that correlates temporally with changes in the content of the microbiome. We also describe the acute and long-term consequences of mitigating hematopoietic ARS (H-ARS) lethality after LD_70/30 doses of WBI in multiple cohorts of mice treated uniformly with radiation mitigators that have a common 4-nitro-phenylsulfonamide (NPS) pharmacophore. Effective NPS mitigators dramatically decrease ARS mortality. There is slightly increased subacute mortality, but the rate of late mortalities is slowed, allowing some mice to live a normal life span, which is not the case for WBI controls. The study has broad relevance to radiation late effects and their potential mitigation and epitomizes the complex interaction between radiation-damaged tissues and immune homeostasis.

In Vivo Models to Study Chemokine Biology

Chemokines are essential mediators of leukocyte movement in vivo. In vitro assays of leukocyte migration cannot mimic the complex interactions with other cell types and matrix needed for cells to extravasate and migrate into tissues. Therefore, in vivo strategies to study the effects and potential relevance of chemokines for the migration of particular leukocyte subsets are necessary. Here, we describe methods to study the effects and endogenous role of chemokine in mice. Advantages and pitfalls of particular models are discussed and we focus on description in model's joint and pleural cavity inflammation and the effects and relevance of CXCR2 and CCR2 ligands on cell migration.

The human salivary proteome is radiation responsive

In the event of a nuclear incident in a heavily populated area, the surge in demand for medical evaluation will likely overwhelm our emergency care system, compromising our ability to care for victims with life-threatening injuries or exposures. Therefore, there exists a need for a rapidly deployable biological assay for radiation exposure that can be performed in the field by individuals with little to no medical training. Saliva is an attractive biofluid for this purpose, due to the relative ease of its collection and the wide array of biomolecules it contains. To determine whether the human salivary proteome is responsive to ionizing radiation exposure, we characterized the abundances of salivary proteins in humans before and after total body irradiation. Using an assay panel targeting 90 analytes (growth factors, chemokines and cytokines), we identified proteins that were significantly radiation responsive in human saliva. The responses of three proteins (monocyte chemo-attractant protein 1, interleukin 8 and intercellular adhesion molecule 1) were confirmed using independent immunoassay platforms and then verified and further characterized in 130 saliva samples from a completely independent set of 38 patients undergoing total body irradiation. The results demonstrate the potential for detecting radiation exposure based on analysis of human saliva.

MKP1 regulates the induction of MCP1 by Streptococcus pneumoniae pneumolysin in human epithelial cells

Epithelial cells act as the first line of host defense against microbes by producing a range of different molecules for clearance. Chemokines facilitate the clearance of invaders through the recruitment of leukocytes. Thus, upregulation of chemokine expression represents an important innate host defense response against invading microbes such as Streptococcus pneumoniae. In this study, we report that the expression of Monocyte Chemotactic Protein 1 (MCP1) was highly induced in response to S. pneumoniae in vitro and in vivo. Among numerous virulence factors, pneumococcal pneumolysin was found to be the major factor responsible for this induction. Furthermore, MCP1 induction was mediated by the p38 mitogen-activated protein kinase (MAPK) whose activation was controlled by MAPK phosphatase 1 (MKP1). Therefore, this study reveals novel roles of pneumolysin in mediating MKP1 expression for the regulation of MCP1 expression in human epithelial cells.

Cigarette smoke, inflammation, and lung injury: a mechanistic perspective

Inflammation is a common feature in the pathogenesis of cigarette smoke-associated diseases. The recruitment of inflammatory cells into the lung following cigarette smoke exposure presents a risk of tissue damage through the release of toxic mediators, including proteolytic enzymes and reactive oxygen species. This review represents a toxicological approach to investigation of cigarette smoke-induced lung injury, with a focus on laboratory studies and an emphasis on inflammatory mechanisms. The studies discussed in this review analyze the role of inflammation and inflammatory mediators in the development of injury. In cases where information relating to cigarette smoke is limited, examples are taken from other models of lung injury applicable to cigarette smoke. The primary aim of the review is to summarize published work so as to permit (1) an evaluation of chronic lung injury and inflammatory responses in animal models, (2) a discussion of inflammatory mediators in the development of chronic injury, and (3) identification of immunological mechanisms of injury. These studies discuss the currently understood roles of cytokines, cell adhesion molecules, and oxidative stress in inflammatory reactions and lung injury. A role for lipocortin 1 (annexin 1), a naturally occurring defense factor against inflammation, is discussed because of the possibility that impaired synthesis and degradation of lipocortin 1 will influence immune responses in animals exposed to cigarette smoke either by augmenting T helper cell Th1 response or by shifting Th1 to Th2 response. While Th1 augmentation will increase the risk for development of emphysema, Th1 to Th2 shift will favor development of asthma.

Pathophysiology of the pleura

The pleural mesothelial cell is an essential cell in maintaining the normal homeostasis of the pleural space and it is also a central component of the pathophysiologic processes affecting the pleural space. In this review, we will review the defense mechanisms of the pleural mesothelium and changes in pleural physiology as a result of inflammatory, infectious, and malignant conditions with a focus on cytokine and chemokine networks. We will also review the processes involved in the pathogenesis of pleural fibrosis.

Resident pleural macrophages are key orchestrators of neutrophil recruitment in pleural inflammation

RATIONALE

The role played by resident pleural macrophages in the initiation of pleural inflammation is currently unclear.

OBJECTIVE

To evaluate the role of resident pleural macrophages in the initiation of inflammation.

METHODS

We have used a conditional macrophage ablation strategy to determine the role of resident pleural macrophages in the regulation of neutrophil recruitment in a murine model of experimental pleurisy induced by the administration of carrageenan and formalin- fixed Staphylococcus aureus.

MEASUREMENTS AND MAIN RESULTS

Conditional macrophage ablation mice express the human diphtheria toxin receptor under the control of the CD11b promoter such that the administration of diphtheria toxin induces ablation of nearly 97% of resident macrophages. Ablation of resident pleural macrophages before the administration of carrageenan or S. aureus dramatically reduced neutrophil influx into the pleural cavity. In the carrageenan model, the reduction in neutrophil infiltration was associated with marked early reduction in the level of macrophage inflammatory protein 2 as well as reduced levels of various cytokines, including tumor necrosis factor alpha, interleukin 6, and interleukin 10. Adoptive transfer of nontransgenic macrophages partially restored neutrophil infiltration. We also stimulated macrophage-depleted and nondepleted pleural cell populations with carrageenan in vitro and determined the production of chemokines and cytokines. Chemokine and cytokine production was markedly reduced by macrophage depletion, reinforcing the role of resident pleural macrophages in the generation of mediators that initiate acute inflammation.

CONCLUSION

These studies indicate a critical role for resident pleural macrophages in sensing perturbation to the local microenvironment and orchestrating subsequent neutrophil infiltration.

Dual regulation of tumor necrosis factor-alpha-induced CCL2/monocyte chemoattractant protein-1 expression in vascular smooth muscle cells by nuclear factor-kappaB and activator protein-1: modulation by type III phosphodiesterase inhibition

Monocyte/macrophage infiltration to the subendothelial space of arterial wall is a critical initial step in atherogenesis, in which CC chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1 (MCP-1) is thought to play a key role. This study investigated the effectiveness of phosphodiesterase inhibitors, including the nonselective pentoxifylline (PTX) and the selective type III (cilostamide) and type IV (denbufylline) inhibitors, on cytokine-induced CCL2/MCP-1 production in cultured rat vascular smooth muscle cells (VSMCs), and the signal transduction mechanisms whereby they act. Our results showed that tumor necrosis factor (TNF)-alpha induced a marked increase in CCL2/MCP-1 production in dose- and time-dependent manners. 2-(2-Amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059), 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio) butadiene (U0126) [both inhibitors of p42/44 mitogen-activated protein kinase (MAPK) kinase], and anthra[1hyphen]9-cd]pyrazol-6(2H)-one (SP600125) [an inhibitor of c-Jun NH(2)-terminal kinases (JNKs)] attenuated TNF-alpha-induced CCL2/MCP-1 production, without affecting I-kappaBalpha degradation or p65/nuclear factor-kappaB (NF-kappaB) nuclear translocation. PD98059 abolished TNF-alpha-activated p42/44 MAPK phosphorylation and c-Fos up-regulation, whereas SP600125 inhibited TNF-alpha-activated JNK and c-Jun phosphorylation. The NF-kappaB inhibitor carbobenzoxy-l-leucyl-l-leucyl-l-leucinal (MG132) attenuated TNF-alpha-induced CCL2/MCP-1 production in the presence of increased phospho-JNK and phospho-c-Jun levels. When SP600125 was added simultaneously, MG132 completely inhibited TNF-alpha-induced CCL2/MCP-1 production. Finally, the pretreatment of VSMCs with PTX or cilostamide, but not denbufylline, reduced TNF-alpha-induced CCL2/MCP-1 production, which was preceded by attenuation of p65/NF-kappaB nuclear translocation, p42/44 MAPK, and JNK-c-Jun phosphorylation, and c-Fos up-regulation. These data indicate that TNF-alpha-stimulated CCL2/MCP-1 production in rat VSMCs is dually regulated by activator protein-1 (AP-1) and NF-kappaB pathways, and inhibition of type III phosphodiesterase contributes substantially to the suppressive effect of PTX on CCL2/MCP-1 production via down-regulation of AP-1 and NF-kappaB signals.

Pulmonary inflammation and edema induced by phospholipase A2: global gene analysis and effects on aquaporins and Na+/K+-ATPase

Victims of snakebite quickly succumb to severe respiratory failure, which can be fatal if left untreated. One of the most toxic components of snake venom is phospholipase A2 (PLA2; EC 3.1.1.4). PLA2 isolated from the elapid, Naja sputatrix, induced pulmonary inflammation and edema when administered intravenously and intratracheally to rats. Analysis of pulmonary gene expression profiles using oligonucleotide microarrays revealed 60 genes whose expression was altered by at least 3-fold in response to intratracheal instillation of PLA2 for 3 h as compared with controls. In addition to genes encoding cytokines and chemokines responsible for inflammatory processes, the Na+/K+-ATPase gene has been found to be involved in edema formation. Real-time PCR, Western blot, and immunohistochemical analyses confirmed that the expression of AQP1 and AQP5 mRNAs and proteins was decreased. Besides providing an experimental model for studies on the pathophysiology of the lung, this investigation yields a clue to the mechanisms by which endogenous PLA2s could mediate inflammation in conditions such as allergy and rheumatoid arthritis.

Targeting monocyte chemoattractant protein-1 signalling in disease

Monocyte chemoattractant protein-1 (MCP-1) has been implicated in many inflammatory and autoimmune diseases. The G-protein-coupled receptor CCR-2B is probably the most important MCP-1 receptor in vivo, and loss of MCP-1 effector function alone is sufficient to impair monocytic trafficking in inflammation models. MCP-1 signalling appears to be a relevant target, especially in rheumatoid arthritis (RA). In RA patients, MCP-1 is produced by synovial cells and infiltrating monocytes, plasma MCP-1 concentrations correlate with swollen joint count, and elevated serum MCP-1 concentrations were found in juvenile RA in patients with active disease. Modulation of MCP-1 signalling in experimental RA showed beneficial effects on inflammation and joint destruction. With respect to chronic neuroinflammation, a critical role for MCP-1 has been established in animal models for multiple sclerosis. In acute neuroinflammation, experimental evidence for a detrimental role of MCP-1 in stroke and excitotoxic injury has been found. Several selective small molecular weight CCR-2B antagonists and MCP-1-blocking antibodies have been described. The proof for the validity of targeting MCP-1 signalling in disease, however, has yet to be established in clinical trials.

[Pleural thickening and tuberculous effusion: searching for predictive data]

Tuberculosis is a very common disease usualy related to bad social-economic conditions and sometimes with associated pleural effusion. Pleural sequelae are referred by some authors as a consequence that may interfere with lung function provoking respiratory failure in some critical situations. Some experts try to find clinical and biochemical parameters in order to detect possibilities that could predict future pleural thickening and necessity of closer vigilance to avoid lung function disability. This study is based on the post-treatment roentgenological pleural findings and their correlation with the initial pleural fluid biochemical data, the volume of the effusions and time of patients complains.