Macrophages cultured in vitro release leukotriene B4 and neutrophil attractant/activation protein (interleukin 8) sequentially in response to stimulation with lipopolysaccharide and zymosan

Neutrophils in aging and aging‐related pathologies

Over the past millennia, life expectancy has drastically increased. While a mere 25 years during Bronze and Iron ages, life expectancy in many European countries and in Japan is currently above 80 years. Such an increase in life expectancy is a result of improved diet, life style, and medical care. Yet, increased life span and aging also represent the most important non-modifiable risk factors for several pathologies including cardiovascular disease, neurodegenerative diseases, and cancer. In recent years, neutrophils have been implicated in all of these pathologies. Hence, this review provides an overview of how aging impacts neutrophil production and function and conversely how neutrophils drive aging-associated pathologies. Finally, we provide a perspective on how processes of neutrophil-driven pathologies in the context of aging can be targeted therapeutically.

Changes in arachidonic acid (AA)- and linoleic acid (LA)-derived hydroxy metabolites and their interplay with inflammatory biomarkers in response to drastic changes in air pollution exposure

BACKGROUND

Untargeted metabolomics analyses have indicated that fatty acids and their hydroxy derivatives may be important metabolites in the mechanism through which air pollution potentiates diseases. This study aimed to use targeted analysis to investigate how metabolites in arachidonic acid (AA) and linoleic acid (LA) pathways respond to short-term changes in air pollution exposure. We further explored how they might interact with markers of antioxidant enzymes and systemic inflammation.

METHODS

This study included a subset of participants (n = 53) from the Beijing Olympics Air Pollution (BoaP) study in which blood samples were collected before, during, and after the Beijing Olympics. Hydroxy fatty acids were measured by liquid chromatography/mass spectrometry (LC/MS). Native total fatty acids were measured as fatty acid methyl esters (FAMEs) using gas chromatography. A set of chemokines were measured by ELISA-based chemiluminescent assay and antioxidant enzyme activities were analyzed by kinetic enzyme assays. Changes in levels of metabolites over the three time points were examined using linear mixed-effects models, adjusting for age, sex, body mass index (BMI), and smoking status. Pearson correlation and repeated measures correlation coefficients were calculated to explore the relationships of metabolites with levels of serum chemokines and antioxidant enzymes.

RESULTS

12-hydroxyeicosatetraenoic acid (12-HETE) decreased by 50.5% (95% CI: -66.5, -34.5; p < 0.0001) when air pollution dropped during the Olympics and increased by 119.4% (95% CI: 36.4, 202.3; p < 0.0001) when air pollution returned to high levels after the Olympics. In contrast, 13-hydroxyoctadecadienoic acid (13-HODE) elevated significantly (p = 0.023) during the Olympics and decreased nonsignificantly after the games (p = 0.104). Interleukin 8 (IL-8) correlated with 12-HETE (r = 0.399, BH-adjusted p = 0.004) and 13-HODE (r = 0.342, BH-adjusted p = 0.014) over the three points; it presented a positive and moderate correlation with 12-HETE during the Olympics (r = 0.583, BH-adjusted p = 0.002) and with 13-HODE before the Olympics (r = 0.543, BH-adjusted p = 0.008).

CONCLUSION

AA- and LA-derived hydroxy metabolites are associated with air pollution and might interact with systemic inflammation in response to air pollution exposure.

Metabolic reprograming of LPS-stimulated human lung macrophages involves tryptophan metabolism and the aspartate-arginosuccinate shunt

Lung macrophages (LM) are in the first line of defense against inhaled pathogens and can undergo phenotypic polarization to the proinflammatory M1 after stimulation with Toll-like receptor agonists. The objective of the present work was to characterize the metabolic alterations occurring during the experimental M1 LM polarization. Human LM were obtained from resected lungs and cultured for 24 hrs in medium alone or with 10 ng.mL-1 lipopolysaccharide. Cells and culture supernatants were subjected to extraction for metabolomic analysis with high-resolution LC-MS (HILIC and reverse phase -RP- chromatography in both negative and positive ionization modes) and GC-MS. The data were analyzed with R and the Worklow4Metabolomics and MetaboAnalyst online infrastructures. A total of 8,741 and 4,356 features were detected in the intracellular and extracellular content, respectively, after the filtering steps. Pathway analysis showed involvement of arachidonic acid metabolism, tryptophan metabolism and Krebs cycle in the response of LM to LPS, which was confirmed by the specific quantitation of selected compounds. This refined analysis highlighted a regulation of the kynurenin pathway as well as the serotonin biosynthesis pathway, and an involvement of aspartate-arginosuccinate shunt in the malate production. Macrophages M1 polarization is accompanied by changes in the cell metabolome, with the differential expression of metabolites involved in the promotion and regulation of inflammation and antimicrobial activity. The analysis of this macrophage immunometabolome may be of interest for the understanding of the pathophysiology of lung inflammatory disesases.

Novel AU-rich proximal UTR sequences (APS) enhance CXCL8 synthesis upon the induction of rpS6 phosphorylation

The role of ribosomal protein S6 (rpS6) phosphorylation in mRNA translation remains poorly understood. Here, we reveal a potential role in modulating the translation rate of chemokine (C-X-C motif) ligand 8 (CXCL8 or Interleukin 8, IL8). We observed that more CXCL8 protein was being secreted from less CXCL8 mRNA in primary macrophages and macrophage-like HL-60 cells relative to other cell types. This correlated with an increase in CXCL8 polyribosome association, suggesting an increase in the rate of CXCL8 translation in macrophages. The cell type-specific expression levels were replicated by a CXCL8- UTR-reporter (Nanoluc reporter flanked by the 5' and 3' UTR of CXCL8). Mutations of the CXCL8-UTR-reporter revealed that cell type-specific expression required: 1) a 3' UTR of at least three hundred bases; and 2) an AU base content that exceeds fifty percent in the first hundred bases of the 3' UTR immediately after the stop codon, which we dub AU-rich proximal UTR sequences (APS). The 5' UTR of CXCL8 enhanced expression at the protein level and conferred cell type-specific expression when paired with a 3' UTR. A search for other APS-positive mRNAs uncovered TNF alpha induced protein 6 (TNFAIP6), another mRNA that was translationally upregulated in macrophages. The elevated translation of APS-positive mRNAs in macrophages coincided with elevated rpS6 S235/236 phosphorylation. Both were attenuated by the ERK1/2 signaling inhibitors, U0126 and AZD6244. In A549 cells, rpS6 S235/236 phosphorylation was induced by TAK1, Akt or PKA signaling. This enhanced the translation of the CXCL8-UTR-reporters. Thus, we propose that the induction of rpS6 S235/236 phosphorylation enhances the translation of mRNAs that contain APS motifs, such as CXCL8 and TNFAIP6. This may contribute to the role of macrophages as the primary producer of CXCL8, a cytokine that is essential for immune cell recruitment and activation.

Leukotriene B4 modulation of murine dendritic cells affects adaptive immunity

Dendritic cells (DCs) link innate and adaptive immunity. The microenvironment generated during the innate immunity affects DCs and the type of adaptive immunity generated. Lipid mediators are released early in inflammation and could modify the functional state of DCs. Leukotriene B₄ (LTB₄) has a wide range of effects on macrophages and in the present study we investigated if it also affects DCs. Murine bone marrow-derived DCs were employed and it was found that stimulation of DCs with LTB4 (10 nM) increased the gene expression of the high affinity receptor BLT-1 but not of BLT-2. It also increased the co-stimulatory molecule CD86 expression but did not affect CD80 and CD40. LTB₄-stimulated DCs acquired the capacity to present antigen to T lymphocytes, evidenced by antigen-specific proliferation of CD4⁺ lymphocytes in co-cultures of ovalbumin-loaded DCs with DO11.10 splenocytes. LTB₄-stimulated DCs induced Treg proliferation and increased Th2 cytokine IL-13 in the co-cultures. Expression of transcription factor genes, Gata3 and Foxp3 (Th2 and Treg, respectively) were also found increased. However, the expression of Th1 transcription factor (Tbet) and Th17 (RorγT) were not affected. These results indicate that LTB₄ affects DCs and modulates the type of adaptive immune response.

Fatty acid binding protein 4/aP2-dependent BLT1R expression and signaling

Previous studies have shown that reduced levels of the adipocyte fatty acid binding protein (FABP)4 (AFABP/aP2), result in metabolic improvement including potentiated insulin sensitivity and attenuated atherosclerosis. Mechanistically, pharmacologic or genetic inhibition of FABP4 in macrophages upregulates UCP2, attenuates reactive oxygen species (ROS) production, polarizes cells toward the anti-inflammatory M2 state, and reduces leukotriene (LT) secretion. At the protein level, FABP4 stabilizes LTA₄ toward chemical hydrolysis, thereby potentiating inflammatory LTC₄ synthesis. Herein, we extend the FABP4-LT axis and demonstrate that genetic knockout of FABP4 reduces expression of the major macrophage LT receptor, LTB₄ receptor 1 (BLT1R), via a ROS-dependent mechanism. Consistent with inflammation driving BLT1R expression, M1 polarized macrophages express increased levels of BLT1R relative to M2 polarized macrophages and treatment with proinflammatory lipopolysaccharide increased BLT1R mRNA and protein expression. In FABP4 knockout macrophages, silencing of UCP2, increased ROS levels and led to increased expression of BLT1R mRNA. Similarly, addition of exogenous H₂O₂ upregulated BLT1R expression, whereas the addition of a ROS scavenger, N-acetyl cysteine, decreased BLT1R levels. As compared with WT macrophages, LTB₄-BLT1R-dependent JAK2-phosphorylation was reduced in FABP4 knockout macrophages. In summary, these results indicate that FABP4 regulates the expression of BLT1R and its downstream signaling via control of oxidative stress in macrophages.

A panel study of airborne particulate matter composition versus concentration: Potential for inflammatory response and impaired pulmonary function in children

BACKGROUND

The relationship between airborne particulate matter (PM) and pulmonary function in children has not been consistent among studies, potentially owing to differences in the inflammatory response to PM, based on PM types and sources. The objective of this study was to investigate the effect of airborne PM on pulmonary function in schoolchildren and its potential for an inflammatory response.

METHODS

Daily morning peak expiratory flow (PEF) was measured in 339 schoolchildren in February 2015. Interleukin (IL)-8 production was assessed in THP1 cells stimulated by airborne PM collected every day during the study period, and these IL-8 concentrations are described as the daily IL-8 levels. A linear mixed model was used to estimate the association between PEF values and the daily levels of suspended PM (SPM), PM diameters smaller than 2.5 μm (PM_2.5), and IL-8.

RESULTS

The daily IL-8 levels were significantly associated with those of SPM and PM_2.5. A 0.83 μg/mL increase in IL-8 levels was significantly associated with a -1.07 L/min (95% confidence interval, -2.05 to -0.08) decrease in PEF. A 12.0 μg/m³ increase in SPM and a 10.0 μg/m³ increase in PM_2.5 were associated with a -1.36 L/min (-2.93 to 0.22) and -1.72 L/min (-3.82 to 0.36) decreases in PEF, respectively. There were no significant relationships between PEF, SPM, and PM_2.5.

CONCLUSIONS

These findings suggest that the effects of airborne PM on pulmonary function in schoolchildren might depend more on the pro-inflammatory response than the mass concentration of the PM.

Purified and Recombinant Hemopexin: Protease Activity and Effect on Neutrophil Chemotaxis

Infusion of the heme-binding protein hemopexin has been proposed as a novel approach to decrease heme-induced inflammation in settings of red blood cell breakdown, but questions have been raised as to possible side effects related to protease activity and inhibition of chemotaxis. We evaluated protease activity and effects on chemotaxis of purified plasma hemopexin obtained from multiple sources as well as a novel recombinant fusion protein Fc-hemopexin. Amidolytic assay was performed to measure the protease activity of several plasma-derived hemopexin and recombinant Fc-hemopexin. Hemopexin was added to the human monocyte culture in the presence of lipopolysaccharides (LPS), and also injected into mice intravenously (i.v.) 30 min before inducing neutrophil migration via intraperitoneal (i.p.) injection of thioglycolate. Control groups received the same amount of albumin. Protease activity varied widely between hemopexins. Recombinant Fc-hemopexin bound heme, inhibited the synergy of heme with LPS on tumor necrosis factor (TNF) production from monocytes, and had minor but detectable protease activity. There was no effect of any hemopexin preparation on chemotaxis, and purified hemopexin did not alter the migration of neutrophils into the peritoneal cavity of mice. Heme and LPS synergistically induced the release of LTB4 from human monocytes, and hemopexin blocked this release, as well as chemotaxis of neutrophils in response to activated monocyte supernatants. These results suggest that hemopexin does not directly affect chemotaxis through protease activity, but may decrease heme-driven chemotaxis and secondary inflammation by attenuating the induction of chemoattractants from monocytes. This property could be beneficial in some settings to control potentially damaging inflammation induced by heme.

Anti-clastogenic effect of b-glucan extracted from barley towards chemically induced DNA damage in rodent cells

b-Glucan (BG) was tested in vitro to determine its potential clastogenic and/or anti-clastogenic activity, and attempts were made to elucidate its possible mechanism of action by using combinations with an inhibitor of DNA polymerase. The study was carried out on cells deficient (CHO-k1) and cells proficient (HTC) in phases I and II enzymes, and the DNA damage was assessed by the chromosomal aberration assay. BG did not show a clastogenic effect, but was anti-clastogenic in both cell lines used, and at all concentrations tested (2.5, 5 and 10 mg/mL) in combination with damage inducing agents (methylmethane sulfonate in cell line CHO-k1, and methylmethane sulfonate or 2-aminoanthracene in cell line HTC). BG also showed a protective effect in the presence of a DNA polymerase b inhibitor (cytosine arabinoside-3-phosphate, Ara-C), demonstrating that BG does not act through an anti-mutagenic mechanism of action involving DNA polymerase b.

Endocannabinoids mediate hyposalivation induced by inflammogens in the submandibular glands and hypothalamus

OBJECTIVE

The aim of this study was to investigate the factors that could participate on salivary glands hypofunction during inflammation and the participation of endocannabinoids in hyposalivation induced by the presence of inflammogens in the submandibular gland (SMG) or in the brain.

DESIGN

Salivary secretion was assessed in the presence of inflammogens and/or the cannabinoid receptor antagonist AM251 in the SMG or in the brain of rats. At the end of the experiments, some systemic and glandular inflammatory markers were measured and histopathological analysis was performed.

RESULTS

The inhibitory effect observed 1h after lipopolysaccharide (LPS, 50μg/50μl) injection into the SMG (ig) was completely prevented by the injection of AM251 (5μg/50μl) by the same route (P<0.05). The LPS (ig)-induced increase in PGE2 content was not altered by AM251 (ig), while the glandular production of TNFα induced by the endotoxin (P<0.001) was partially blocked by it. Also, LPS injection produced no significant changes in the wet weight of the SMG neither damage to lipid membranes of its cells, nor significant microscopic changes in them, after hispopathological analysis, compared to controls. Finally, TNFα (100ng/5μl) injected intracerebro-ventricularly (icv) inhibited methacholine-induced salivary secretion evaluated 30min after (P<0.01), but the previous injection of AM251 (500ng/5μl, icv) prevented completely that effect.

CONCLUSION

We conclude that endocannabinoids mediate the hyposialia induced by inflammogens in the SMG and in the brain. The hypofunction would be due to changes on signalling pathway produced by inflammatory compounds since anatomical changes were not observed.

LPS-induced chemokine expression in both MyD88-dependent and -independent manners is regulated by Cot/Tpl2-ERK axis in macrophages

LPS signaling is mediated through MyD88-dependent and -independent pathways, activating NF-?B, MAP kinases and IRF3. Cot/Tpl2 is an essential upstream kinase in LPS-mediated activation of ERKs. Here we explore the roles of MyD88 and Cot/Tpl2 in LPS-induced chemokine expression by studying myd88(-/-) and cot/tpl2(-/-) macrophages. Among the nine LPS-responsive chemokines examined, mRNA induction of ccl5, cxcl10, and cxcl13 is mediated through the MyD88-independent pathway. Notably, Cot/Tpl2-ERK signaling axis exerts negative effects on the expression of these three chemokines. In contrast, LPS-induced gene expression of ccl2, ccl7, cxcl2, cxcl3, ccl8, and cxcl9 is mediated in the MyD88-dependent manner. The Cot/Tpl2-ERK axis promotes the expression of the first four and inhibits the expression of the latter two. Thus, LPS induces expression of multiple chemokines through various signaling pathways in macrophages.

Purification of a lectin from Arisaema erubescens (Wall.) Schott and its pro-inflammatory effects

The monocot lectin from the tubers of Arisaema erubescens (Wall.) Schott has been purified by consecutive hydrophobic chromatography and ion exchange chromatography methods. The molecular weight of this A. erubescens lectin (AEL) was determined to be about 12 kDa by high performance liquid chromatography (HPLC) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) methods. AEL could agglutinate rabbit erythrocytes. The haemagglutination activity of AEL was only inhibited by asialofetuin, while monosaccharide did not react. Rat paw edema and neutrophil migration models were used to investigate the pro-inflammatory activity of AEL. AEL (100 and 200 μg/paw) could induce significant rat paw edema. In addition, AEL (100, 200 and 300 μg/mL/cavity) could induce significant and dose-dependent neutrophil migration in the rat peritoneal cavities. Besides, AEL at doses ranging from 100 to 300 μg/mL/cavity could significantly increase the concentration of nitric oxide (NO), prostaglandin E₂ (PGE₂) and tumor necrosis factor alpha (TNF-α) in peritoneal fluid. As compared with control animals, 75% depletion in the number of resident cells following peritoneal lavage did not reduce the AEL-induced neutrophil migration. However, pre-treatment with 3% thioglycollate which increased the peritoneal macrophage population by 201%, enhanced the neutrophil migration induced by AEL (200 μg/mL/cavity) (p < 0.05). Reduction of peritoneal mast cell population by chronic treatment of rat peritoneal cavities with compound 48/80 (N-methyl-p-methoxyphenethylamine with formaldehyde) did not modify AEL-induced neutrophil migration. The results provided the basis for identifying the toxic components of A. erubescens and AEL could be a new useful tool for pro-inflammatory research.

Neutrophilic airways inflammation in lung cancer: the role of exhaled LTB-4 and IL-8

BACKGROUND

Recent advances in lung cancer biology presuppose its inflammatory origin. In this regard, LTB-4 and IL-8 are recognized to play a crucial role in neutrophil recruitment into airways during lung cancer.Notwithstanding the intriguing hypothesis, the exact role of neutrophilic inflammation in tumour biology remains complex and not completely known.The aim of this study was to give our contribution in this field by investigating LTB-4 and IL-8 in the breath condensate of NSCLC patients and verifying their role in cancer development and progression.

METHOD

We enrolled 50 NSCLC patients and 35 controls. LTB-4 and IL-8 concentrations were measured in the breath condensate and the blood of all the subjects under study using EIA kits. Thirty NSCLC patients and ten controls underwent induced sputum collection and analysis.

RESULTS

LTB-4 and IL-8 resulted higher in breath condensate and the blood of NSCLC patients compared to controls. Significantly higher concentrations were found as the cancer stages progressed. A positive correlation was observed between exhaled IL-8 and LTB-4 and the percentage of neutrophils in the induced sputum.

CONCLUSION

The high concentrations of exhaled LTB-4 and IL-8 showed the presence of a neutrophilic inflammation in the airways of NSCLC patients and gave a further support to the inflammatory signalling in lung cancer. These exhaled proteins could represent a suitable non-invasive marker in the diagnosis and monitoring of lung cancer.

Participation of the endocannabinoid system in lipopolysaccharide-induced inhibition of salivary secretion

OBJECTIVE

The aim of the present paper was to assess whether lipopolysaccharide (LPS)-induced inhibition of salivary secretion involves the activation of the endocannabinoid system and the participation of tumor necrosis factor (TNF)alpha in the submandibular gland.

DESIGN

Pharmacological approaches were performed by using CB1 and/or CB2 cannabinoid receptor antagonists, AM251 and AM630, respectively, injected into the submandibular gland, to study the participation of the endocannabinoid system in LPS inhibitory effects on metacholine-induced salivary secretion. To assess the participation of TNFalpha on LPS inhibitory effects, salivary secretion was studied in LPS treated rats after the intraglandular injection of etanercept, a soluble form of TNF receptor which blocks TNFalpha action. Finally, to evaluate the possible interplay between endocannabinoids and TNFalpha on the submandibular gland function reduced during LPS challenge, the salivary secretion was studied after the intraglandular injection of this cytokine alone or concomitantly with AM251 and AM630.

RESULTS

AM251 and AM630, injected separately or concomitantly, partially prevented LPS-induced inhibition of salivation. Also, anandamide synthase activity was increased in submandibular glands extracted from rats 3h after LPS injection, suggesting that the endocannabinoid system was activated in response to this challenge. On the other hand, etanercept, prevented the inhibitory effect of LPS on salivary secretion and moreover, TNFalpha injected intraglandularly inhibited salivary secretion, being this effect prevented by AM251 and AM630 injected concomitantly.

CONCLUSION

The present results demonstrate the participation of the endocannabinoid system and TNFalpha on salivary responses during systemic inflammation induced by LPS.

The effects of ambient particulate matter on human alveolar macrophage oxidative and inflammatory responses

Epidemiologic and occupational studies demonstrated that ambient particulate matter (PM) and diesel exhaust particles (DEP) exert deleterious effects on human cardiopulmonary health, including exacerbation of pre-existing lung disease and development of respiratory infections. The effects of ambient PM on lung cell responsiveness are poorly defined. Human alveolar macrophages (AM) were exposed to SRM 1649 (Washington, DC, urban dust; UD), SRM 2975 (forklift diesel exhaust particles; DEP), and fine or coarse ambient PM collected in Chapel Hill, NC, during the late fall (November) and early summer (June) of 2001-2002. AM were subsequently incubated with lipopolysaccharide (LPS), phorbol myristate acetate (PMA), or calcium ionophore A23817 for 6 or 24 h after PM exposure. UD and DEP markedly suppressed O2- release 24 h post-PM exposure. UD exposure significantly inhibited tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 release after exposure to 10 nanog/ml LPS. DEP significantly suppressed only TNF-alpha and IL-6 release. Suppressed cytokine release may also be produced by reduced cellular cytokine production. Data suggested that decreased cytokine release is not produced by the presence of benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon. Comparison of TNF-alpha release after LPS, PMA, or A23817 revealed that suppressive effects of UD are LPS dependent, whereas inhibitory effects of DEP may work across multiple mechanistic pathways. November and June Chapel Hill PM exposure stimulated TNF-alpha and IL-8 release before LPS exposure. Fine and coarse November PM exposure markedly suppressed TNF-alpha release 6 h after LPS stimulation, but appeared to exert a stimulatory effect on IL-8 release 24 h after LPS exposure. June fine and coarse PM suppressed IL-8 release after LPS exposure. Data suggest that seasonal influences on PM composition affect AM inflammatory response before and after bacterial exposure. Overall, delayed or inhibited AM immune responses to LPS after PM exposure suggest human exposure to ambient PM may enhance pulmonary susceptibility to respiratory infections.

A distinctive role of the leukotriene B4 receptor BLT1 in osteoclastic activity during bone loss

Although leukotriene B(4) (LTB(4)) is produced in various inflammatory diseases, its functions in bone metabolism remain unknown. Using mice deficient in the high-affinity LTB(4) receptor BLT1, we evaluated the roles of BLT1 in the development of two bone resorption models, namely bone loss induced by ovariectomy and lipopolysaccharide. Through observations of bone mineral contents and bone morphometric parameters, we found that bone resorption in both models was significantly attenuated in BLT1-deficient mice. Furthermore, osteoclasts from BLT1-deficient mice showed reduced calcium resorption activities compared with wild-type osteoclasts. Osteoclasts expressed BLT1, but not the low-affinity LTB(4) receptor BLT2, and produced LTB(4). LTB(4) changed the cell morphology of osteoclasts through the BLT1-Gi protein-Rac1 signaling pathway. Given the causal relationship between osteoclast morphology and osteoclastic activity, these findings suggest that autocrine/paracrine LTB(4) increases the osteoclastic activity through the BLT1-Gi protein-Rac1 signaling pathway. Inhibition of BLT1 functions may represent a strategy for preventing bone resorption diseases.

Protective effects of beta-glucan extracted from barley against benzo[a]pyrene-induced DNA damage in hepatic cell HepG2

The aim of the present study was to assess the genotoxic and antigenotoxic effect of beta-glucan (BG) extracted from barley. The genotoxicity of BG was tested in the single-cell gel electrophoresis assays (SCGE)/HepG2 test system. Moreover, the protective effects of BG against the genotoxicity of B[a]P were studied to delineate its mechanism of antigenotoxicity using four different treatment protocols - pre-treatment, simultaneous simple, simultaneous with pre-incubation, and post-treatment. The results showed that the compound itself was devoid of mutagenic activity at the three lower concentrations studied (1, 5, and 25microg/mL); however, genotoxic and cytotoxic effects were seen at 100 and 200microg/mL, respectively. In combination experiments with B[a]P, pronounced inhibition of DNA migration in the SCGE assay was observed in the two simultaneous treatments, and a smaller reduction was observed in the two other treatments. Thus, the data suggest that BG acts through binding to the genotoxic compound or capturing free radicals produced during its activation. However, the protective effects observed with pre-treatment and post-treatment suggest that the BG may be modulating cell metabolism.

Pro-inflammatory effect in mice of CvL, a lectin from the marine sponge Cliona varians

CvL, a lectin from the marine sponge Cliona varians agglutinated type A papainized erythrocytes and was strongly inhibited by d-galactose and sucrose. Models of leukocyte migration in vivo were used to study the inflammatory activity of CvL through of mouse paw oedema and peritonitis. Effect of CvL on peritoneal macrophage activation was analysed. Effects of corticoids and NSAIDS drugs were also evaluated on peritonitis stimulated by CvL. Results showed that mouse hind-paw oedema induced by subplantar injections of CvL was dose dependent until 50 microg/cavity. This CvL dose when administered into mouse peritoneal cavities induced maxima cell migration (9283 cells/microL) at 24 h after injection. This effect was preferentially inhibited by incubation of CvL with the carbohydrates d-galactose followed by sucrose. Pre-treatment of mice with 3% thioglycolate increases the peritoneal macrophage population 2.3 times, and enhanced the neutrophil migration after 24 h CvL injection (75.8%, p<0.001) and no significant effect was observed in the presence of fMLP. Finally, pre-treatment of mice with dexamethasone (cytokine antagonist) decreased (65.6%, p<0.001), diclofenac (non-selective NSAID) decreased (34.5%, p<0.001) and Celecoxib (selective NSAID) had no effect on leukocyte migration after submission at peritonitis stimulated by CvL, respectively. Summarizing, data suggest that CvL shows pro-inflammatory activity, inducing neutrophil migration probably by pathway on resident macrophage activation and on chemotaxis mediated by cytokines.

Inhibition of Toll-like receptor 4 breaks the inflammatory loop in autoimmune destructive arthritis

OBJECTIVE

Degeneration of extracellular matrix of cartilage leads to the production of molecules capable of activating the immune system via Toll-like receptor 4 (TLR-4). The objective of this study was to investigate the involvement of TLR-4 activation in the development and progression of autoimmune destructive arthritis.

METHODS

A naturally occurring TLR-4 antagonist, highly purified lipopolysaccharide (LPS) from Bartonella quintana, was first characterized using mouse macrophages and human dendritic cells (DCs). Mice with collagen-induced arthritis (CIA) and mice with spontaneous arthritis caused by interleukin-1 receptor antagonist (IL-1Ra) gene deficiency were treated with TLR-4 antagonist. The clinical score for joint inflammation, histologic characteristics of arthritis, and local expression of IL-1 in joints were evaluated after treatment.

RESULTS

The TLR-4 antagonist inhibited DC maturation induced by Escherichia coli LPS and cytokine production induced by both exogenous and endogenous TLR-4 ligands, while having no effect on these parameters by itself. Treatment of CIA using TLR-4 antagonist substantially suppressed both clinical and histologic characteristics of arthritis without influencing the adaptive anti-type II collagen immunity crucial for this model. Treatment with TLR-4 antagonist strongly reduced IL-1beta expression in articular chondrocytes and synovial tissue. Furthermore, such treatment inhibited IL-1-mediated autoimmune arthritis in IL-1Ra(-/-) mice and protected the mice against cartilage and bone pathology.

CONCLUSION

In the present study, we demonstrate for the first time that inhibition of TLR-4 suppresses the severity of experimental arthritis and results in lower IL-1 expression in arthritic joints. Our data suggest that TLR-4 might be a novel target in the treatment of rheumatoid arthritis.

Evaluation of antimutagenic activity and mechanisms of action of β-glucan from barley, in CHO-k1 and HTC cell lines using the micronucleus test

Due to the need to identify new antimutagenic agents and to determine their mechanism of action, the present study examined the mechanism of action of the beta-glucan with regard to antimutagenicity using the micronucleus assay in CHO-k1 and HTC cell lines. The mutagenicity experiments were performed with three different concentrations of beta-glucan (5, 10, and 20 microg/mL), in wich only the highest dose showed mutagenic activity. In the antimutagenicity experiments, the same concentrations of beta-glucan were combined with a mutagenic agent, methylmethane sulfonate, or 2-aminoanthracene, using four different treatment protocols: pre-treatment, simultaneous treatment (simple and with pre-incubation), and post-treatment. The results indicate that the CHO-k1 cell line treated with MMS presented a chemopreventive activity for all the doses of beta-glucan in the different treatment protocols, except for the lowest dose in post-treatment. When HTC cell line treated with MMS is analysed, a chemopreventive activity can be verified for the highest dose in both pre- and post-treatment. For the simple simultaneous treatment, the three doses demonstrated efficacy, while for the simultaneous treatment with pre-incubation only the intermediate concentration was effective. In HTC treated with 2AA both the lowest dose in the pre-treatment protocol and the post-treatment protocol did not show efficacy in preventing DNA damage. The evaluation of the different protocols and the damage decrease percentages observed suggest that beta-glucan has both desmutagenic and bioantimutagenic activity. It is necessary, however, to note that efficacy and mechanism of action are subject to variation when compared the two cell lines, since in HTC, representing a drug-metabolizing system, this substance can show a diminished chemopreventive capacity.

Protective effect of beta-glucan extracted from Saccharomyces cerevisiae, against DNA damage and cytotoxicity in wild-type (k1) and repair-deficient (xrs5) CHO cells

A large number of functional foods, including those that contain beta-glucan, have been shown to prevent the development of cancer and other chronic diseases. The aim of the present study was to elucidate its mechanism of action, as well as to understand its effects as an antigenotoxic, anticlastogenic agent, and to determine its capacity to preserve cell viability. The investigation was carried out in the CHO-k1 and CHO-xrs5 cell lines. The cytokinesis-blocked micronucleus assay indicated that the different doses of beta-glucan examined (5, 10, 20 and 40 microg/ml) did not show clastogenic effects. In the CHO-k1 cell line, a chemopreventive effect could be observed in all the protocols tested: pre-treatment (% reduction of 35.0-57.3), simultaneous treatment (simple--5 reduction of 19.7-55.6 and with pre-incubation--of 42.7-56.4) and post-treatment (% reduction of 17.9-37.6). This finding indicates mechanisms of action involving desmutagenesis and bioantimutagenesis, albeit the latter having a lesser role. However, in the repair-deficient CHO-xrs5 cells, beta-glucan did not show a protective effect with post-treatment (% reduction of 2.96), thus supporting the involvement of bioantimutagenesis. The comet assay in CHO-k1 cells demonstrated that beta-glucan has neither a genotoxic nor an antigenotoxic effect. Cell viability tests indicated that beta-glucan preserves cell viability in both cell lines, preventing apoptotic events. These findings suggest that beta-glucan, when present in foods, could provide them with nutraceutical characteristics and act as a dietary supplement, or that beta-glucan could be used in new drug development.

Cytochrome P450 4F subfamily: at the crossroads of eicosanoid and drug metabolism

The cytochrome P450 4F (CYP4F) subfamily has over the last few years come to be recognized for its dual role in modulating the concentrations of eicosanoids during inflammation as well as in the metabolism of clinically significant drugs. The first CYP4F was identified because it catalyzed the hydroxylation of leukotriene B(4) (LTB(4)) and since then many additional members of this subfamily have been documented for their distinct catalytic roles and functional significance. Recent evidence emerging in relation to the temporal change of CYP4F expression in response to injury and infection supports an important function for these isozymes in curtailing inflammation. Their tissue-dependent expression, isoform-based catalytic competence and unique response to the external stimuli imply a critical role for them to regulate organ-specific functions. From this standpoint variations in relative CYP4F levels in humans may have direct influence on the metabolic outcome through their ability to generate and/or degrade bioactive eicosanoids or therapeutic agents. This review covers the enzymatic characteristics and regulatory properties of human and rodent CYP4F isoforms and their physiological relevance to major pathways in eicosanoid and drug metabolism.

Effect of salivary gland extract of Leishmania vector, Lutzomyia longipalpis, on leukocyte migration in OVA-induced immune peritonitis

Salivary gland extracts (SGE) from Lutzomyia longipalpis potentate L. major infection by inducing a Th2 immune response. However, the effect of SGE on the effector phase of immune response is not known. Herein, we demonstrate that SGE inhibited neutrophil migration in ovalbumin (OVA)-induced peritonitis in immunized mice. SGE pretreatment of mice inhibited OVA-induced CD4+ and CD8+ T lymphocyte migration. The OVA-induced production of TNF-alpha, IL-1beta and leukotriene B4 (LTB4), neutrophil chemotactic mediators in this model, were inhibited by SGE. On the other hand, SGE enhanced production of IL-10 and IL-4. In naive mice, SGE also blocked LTB4-induced neutrophil migration, but not that induced fMLP. Moreover, co-incubation of LTB4 (but not fMLP, TNF-alpha and MIP-1alpha) with SGE inhibited the ability of LTB4 to induce neutrophil migration in vivo and in vitro. Altogether, the results suggest that SGE has anti-inflammatory properties that are associated with inhibition of TNF-alpha and LTB4 production and/or with the neutrophil chemotactic activity of LTB4. The effectiveness of SGE in inhibiting neutrophil migration and inflammatory mediators release in a Th1 immune inflammatory response model reinforces the need for isolation of the compounds responsible for these activities, which could be used as prototypes for the development new anti-inflammatory drugs.

Paradoxical attenuation of leukocyte rolling in response to ischemia- reperfusion and extracorporeal blood circulation in inflamed tissue

In contrast to acute preparations such as the exteriorized mesentery or the cremaster muscle, chronically instrumented chamber models allow one to study the microcirculation under “physiological” conditions, i.e., in the absence of trauma-induced leukocyte rolling along the venular endothelium. To underscore the importance of studying the naive microcirculation, we implanted titanium dorsal skinfold chambers in hamsters and used intravital fluorescence microscopy to study venular leukocyte rolling in response to ischemia-reperfusion injury or extracorporeal blood circulation. The experiments were performed in chambers that fulfilled all well-established criteria for a physiological microcirculation as well as in chambers that showed various extents of leukocyte rolling due to trauma, hemorrhage, or inflammation. In ideal chambers with a physiological microcirculation (<30 rolling leukocytes/mm vessel circumference in 30 s), ischemia-reperfusion injury and extracorporeal blood circulation significantly stimulated leukocyte rolling along the venular endothelium and, subsequently, firm leukocyte adhesion. In contrast, both stimuli failed to elicit leukocyte rolling in borderline chambers (30–100 leukocytes/mm), and in blatantly inflamed chambers with yet higher numbers of rolling leukocytes at baseline (>100 leukocytes/mm), we observed a paradoxical reduction of leukocyte rolling after ischemia-reperfusion injury or extracorporeal blood circulation. A similar effect was observed when we superfused leukotriene B4 (LTB4) onto the chamber tissue. The initial increase in leukocyte rolling in response to an LTB4 challenge was reversed by a second superfusion 90 min later. These observations underscore 1) the benefit of studying leukocyte-endothelial cell interaction in chronically instrumented chamber models and 2) the necessity to strictly adhere to well-established criteria of a physiological microcirculation.

LTB4 is present in exudative pleural effusions and contributes actively to neutrophil recruitment in the inflamed pleural space

The pleural space is a virtual compartment between the lung and chest wall that becomes filled with fluid and inflammatory cells during a variety of respiratory diseases. Here, we study the potential role of the eicosanoid metabolite leukotriene B4 (LTB4) in disparate diseases leading to acute (pneumonia) or chronic (tuberculosis, cancer) inflammation of the pleural space. LTB4 concentrations were significantly higher in pleural fluid due to pneumonia, tuberculosis and cancer with respect to congestive heart failure and correlated with neutrophil elastase, which is used as an indication of state of activation of neutrophils in the pleural space. Moreover, pleural LTB4 was biologically active, as an anti-LTB4 antibody partially neutralized the chemotactic activity of parapneumonic, tuberculous and cancer effusions. Macrophages, neutrophils, lymphocytes, mesothelial cells and cancer cells all expressed mRNA for 5-lipoxygenase, the enzyme that initiates leukotriene synthesis leading to the production of LTB4, in exudative pleural effusions. Upon stimulation in transudative pleural effusions, pleural macrophages produced, in a time-dependent fashion, a significantly higher concentration of LTB4 than mesothelial cells. These studies demonstrate that different cell types are capable of producing LTB4 in the inflamed pleural space and that this mediator may play a crucial role in the recruitment of neutrophils into the pleural space.

Lipopolysaccharide induces anandamide synthesis in macrophages via CD14/MAPK/phosphoinositide 3-kinase/NF-kappaB independently of platelet-activating factor

Macrophage-derived endocannabinoids have been implicated in endotoxin (lipopolysaccharide (LPS))-induced hypotension, but the endocannabinoid involved and the mechanism of its regulation by LPS are unknown. In RAW264.7 mouse macrophages, LPS (10 ng/ml) increases anandamide (AEA) levels >10-fold via CD14-, NF-kappaB-, and p44/42-dependent, platelet-activating factor-independent activation of the AEA biosynthetic enzymes, N-acyltransferase and phospholipase D. LPS also induces the AEA-degrading enzyme fatty acid amidohydrolase (FAAH), and inhibition of FAAH activity potentiates, whereas actinomycin D or cycloheximide blocks the LPS-induced increase in AEA levels and N-acyltransferase and phospholipase D activities. In contrast, cellular levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) are unaffected by LPS but increased by platelet-activating factor. LPS similarly induces AEA, but not 2-AG, in mouse peritoneal macrophages where basal AEA levels are higher, and the LPS-stimulated increase in AEA is potentiated in cells from FAAH-/- as compared with FAAH+/+ mice. Intravenous administration of 107 LPS-treated mouse macrophages to anesthetized rats elicits hypotension, which is much greater in response to FAAH-/- than FAAH+/+ cells and is susceptible to inhibition by SR141716, a cannabinoid CB1 receptor antagonist. We conclude that AEA and 2-AG synthesis are differentially regulated in macrophages, and AEA rather than 2-AG is a major contributor to LPS-induced hypotension.

Prolonged lipopolysaccharide inhibits leukotriene synthesis in peritoneal macrophages: mediation by nitric oxide and prostaglandins

Resident rat peritoneal macrophages synthesize a variety of prostanoids and leukotrienes from arachidonic acid. Overnight treatment with lipopolysaccharide (LPS) induces the synthesis of cyclooxygenase-2 (COX-2) and an altered prostanoid profile that emphasizes the preferential conversion of arachidonic acid to prostacyclin and prostaglandin E2. In these studies, we report that exposure to LPS also caused a strong suppression of 5-lipoxygenase but not 12-lipoxygenase activity, indicated by the inhibition of synthesis of both leukotriene B4 and 5-hydroxyeicosatetraenoic acid (5-HETE), but not of 12-HETE. Inhibition of 5-lipoxygenase activity by LPS was both time- and dose-dependent. Treatment of macrophages with prostaglandin E2 partially inhibited leukotriene synthesis, and cyclooxygenase inhibitors partially blocked the inhibition of leukotriene generation in LPS-treated cells. In addition to COX-2, nitric oxide synthase (NOS) was also induced by LPS. Treatment of macrophages with an NO donor mimicked the ability of LPS to significantly reduce leukotriene B4 synthesis. Inhibition of NOS activity in LPS-treated cells blunted the suppression of leukotriene synthesis. Inhibition of both inducible NOS and COX completely eliminated leukotriene suppression. Finally, macrophages exposed to prolonged LPS demonstrated impaired killing of Klebsiella pneumoniae and the combination of NOS and COX inhibitors restored killing to the control level. These results indicate that prolonged exposure to LPS severely inhibits leukotriene production via the combined action of COX and NOS products. The shift in mediator profile, to one that minimizes leukotrienes and emphasizes prostacyclin, prostaglandin E2 and NO, provides a signal that reduces leukocyte function, as indicated by impaired killing of Gram-negative bacteria.

Modulation of plasma levels of soluble adhesion molecules and nitric oxide in healthy volunteers by exposure to swine dust

Short-time exposure to swine dust causes an intense airways inflammation and symptoms of systemic inflammation in healthy volunteers. Here, we sought to study whether this response involved signs of endothelial cell activation. Peripheral blood cell counts and plasma levels of sE-selectin, sP-selectin, sICAM-1, interleukin-8, nitrite and nitrate were measured in blood samples from 17 healthy subjects before and after a 3-hr exposure to swine dust in a swine confinement building. Dust exposure induced a 3-fold increase of blood neutrophil p = 0.0009) and 1.5-fold increase of monocyte counts (p = 0.0047). IL-8 was detected in 15 individuals after exposure (p = 0.001). Endothelial cell markers such as sICAM and nitrate increased by 10 and 34% resp. (p = 0.011 and 0.017), whereas sE-selectin remained unchanged and sP-selectin was reduced by 15% (p = 0.031). Thus, short time exposure to swine dust induced a systemic inflammatory response with evidence of endothelial and inflammatory cell activation.

Modulating airway defenses against microbes

Prevention and treatment of respiratory infections remain an important health care challenge as the US population ages, contains more susceptible or high-risk people, and encounters new pathogens or antibiotic resistant bacteria. Reasonably protective vaccines against very common microbes are available for childhood and adult immunization, but, generally, these are underutilized. A broader definition of higher risk individuals is evolving, which will include more for immunization. Different approaches to vaccine development through design of new component vaccines are necessary. This review has updated host defense mechanisms at three levels in the human respiratory tract: naso-oropharynx (upper airways), conducting airways, and alveolar space. Examples of representative pathogenic microbes have been inserted at the respective airway segment where they may colonize or create infection (influenza, measles virus, Porphyromonas gingivalis causing periodontitis, Bordetella pertussis, Chlamydia pneumoniae, Streptococcus pneumoniae, and Bacillus anthracis ). Hopefully, microbe-host interactions will suggest new approaches for preventing these kinds of infections.

Increased levels of interleukin-8 in BAL fluid from smokers susceptible to pulmonary emphysema

BACKGROUND

It has previously been shown that smokers with computed tomographic (CT) evidence of subclinical emphysema have signs of neutrophil activation, despite having no appreciable increase in the number of neutrophils in their bronchoalveolar lavage (BAL) fluid.

METHODS

The levels of the following chemoattractants in BAL fluid from 61 community based older volunteers classified into four groups according to current smoking status and the presence or absence of emphysema were determined: interleukin 8 (IL-8), epithelial neutrophil activating protein 78 (ENA-78) and leukotriene B(4) (LTB(4)) which are primarily chemotactic for neutrophils; monocyte chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) which are predominantly chemotactic for mononuclear leucocytes.

RESULTS

Of the five chemoattractants studied, only the level of IL-8 in BAL fluid clearly distinguished between subjects with and without emphysema among current smokers (median values 34.7 and 12.2 pg/ml, respectively, p<0.01). In addition, the levels of IL-8 and neutrophil elastase-alpha(1) protease inhibitor complex in BAL fluid were significantly correlated (r=0.65, p<0.01). There was no difference in either the release of IL-8 from cultured alveolar macrophages at 24 hours or the expression of IL-8 messenger RNA of alveolar macrophages in the two groups of current smokers with and without emphysema.

CONCLUSION

An accelerated response of IL-8 to chronic smoking is a factor that characterises those smokers who are susceptible to pulmonary emphysema, although the cellular source of IL-8 remains to be determined.

Tumour necrosis factor-alpha and leukotriene B(4) mediate the neutrophil migration in immune inflammation

1. We investigated the mediators responsible for neutrophil migration induced by ovalbumin (OVA) in immunized mice and the mechanisms involved in their release. 2. OVA administration promoted dose- and time-dependent neutrophil migration in immunized, but not in non-immunized mice, which was mediated by leukotriene B(4) (LTB(4)) and tumour necrosis factor (TNF)alpha, since it was inhibited by LTB(4) synthesis inhibitor (MK 886) or by LTB(4) receptor antagonist (CP 105,696), by dexamethasone and by antiserum to TNFalpha (82, 85, 63 and 87%, respectively). Confirming TNFalpha involvement, OVA challenge in immunized p55 TNF receptor deficient mice (p55(-/-)) did not promote neutrophil migration (control: 2.90 +/- 0.68; p55(-/-): 0.92+/-0.23 x 10(6) neutrophils cavity(-1)). 3. OVA-stimulated peritoneal cells from immunized mice released a neutrophil chemotactic factor which mimicked, in naive mice, neutrophil migration induced by OVA. 4. Supernatant chemotactic activity is due to TNFalpha and LTB(4), since its release was inhibited by MK 886 (93%) and dexamethasone (90%), and significant amounts of these mediators were detected. 5. TNFalpha and LTB(4) released by OVA challenge seem to act through a sequential mechanism, since MK 886 inhibited (88%) neutrophil migration induced by TNFalpha. Moreover, peritoneal cells stimulated with TNFalpha released LTB(4). 6. CD(4)(+) T cells are responsible for TNFalpha release, because the depletion of this subset prevented the release of TNFalpha (control: 400 +/- 25; immunized: 670 +/- 40; CD(4)(+) depleted: 435 +/- 18 pg ml(-1)). 7. In conclusion, neutrophil migration induced by OVA depends on TNFalpha released by CD(4)(+) cells, which acts through an LTB(4)-dependent mechanism.

The anti-inflammatory profile of inhaled corticosteroids combined with salmeterol in asthmatic patients

Inhaled corticosteroid (ICS) therapy such as fluticasone propionate (FP) is effective in moderate-to-severe asthma, but for patients on ICS who still experience symptoms, treatment guidelines recommend either increasing the dose of ICS or adding a long-acting beta2-agonist such as salmeterol or formoterol. Several studies have now shown that adding salmeterol provides greater clinical benefit than increasing the dose of ICS, raising the question of whether salmeterol has an additive or complementary anti-inflammatory effect to that of ICS. Recent studies on bronchial biopsies and bronchoalveolar lavage from asthmatic patients treated with either salmeterol. FP or placebo in addition to low-dose ICS have demonstrated that addition of salmeterol produces independent or additional reductions in several pro-inflammatory cells, cytokines and cell adhesion molecules compared with FP. Such complementary anti-inflammatory effects may explain the improved control of asthma symptoms and exacerbations observed when salmeterol is added to low-dose ICS therapy, and may help to modify the long-term sequelae of asthma. These findings also indicate, contrary to earlier speculation, that salmeterol does not have a pro-inflammatory effect or mask persistent airway inflammation. This review presents the results of recent studies and suggests possible mechanisms for the additional antiinflammatory effects of salmeterol.

Prolonged exposure to lipopolysaccharide inhibits macrophage 5-lipoxygenase metabolism via induction of nitric oxide synthesis

LPS from bacteria can result in the development of sepsis syndrome and acute lung injury. Although acute exposure to endotoxin primes leukocytes for enhanced synthesis of leukotrienes (LT), little is known about the effect of chronic exposure. Therefore, we determined the effect of prolonged LPS treatment on 5-lipoxygenase (5-LO) metabolism of arachidonic acid in alveolar macrophages (AM) and in peripheral blood monocytes. Pretreatment of AM with LPS caused time- and dose-dependent suppression of LT synthetic capacity. LPS pretreatment failed to inhibit arachidonic acid (AA) release. The fact that LPS inhibited LT synthesis from endogenous AA more than from exogenous AA suggested an effect on 5-LO-activating protein (FLAP). In addition, an inhibitory effect of LPS treatment on AM 5-LO activity was suggested by cell-free 5-LO enzyme assay. No effect on the expression of either 5-LO or FLAP proteins was observed. New protein synthesis was necessary for LPS-induced reduction of 5-LO metabolism in AM, and immunoblotting demonstrated marked induction of NO synthase (NOS). Inhibition by LPS was reproduced by an NO donor and was abrogated by inhibitors of constitutive and inducible NOS. Compared with AM, peripheral blood monocytes exhibited no suppression by LPS of 5-LO metabolism and no induction of inducible NOS. We conclude that prolonged exposure to LPS impairs AM 5-LO metabolism by NO-mediated suppression of both 5-LO and FLAP function. Because LT contribute to antimicrobial defense, this down-regulation of 5-LO metabolism may contribute to the increased susceptibility to pneumonia in patients following sepsis.

House dust induces IL-6 and IL-8 response in A549 epithelial cells

The in vitro potency of house dust to induce cytokine response in A549 lung epithelial cells was studied. Dusts collected from carpet, bed, shelf and floor of a villa and an apartment by vacuuming were found to trigger the production of interleukin-8 (IL-8) and interleukin-6 (IL-6) in a dose-dependent manner, and the interleukin production was several-fold higher than of swine dust (used as a positive control). The IL-8 and IL-6 production of pure Escherichia coli lipopolysaccharide was significantly lower than of the dusts and a peptidoglycan-polysaccharide complex did not show any stimulatory effect at all. The lipopolysaccharide and peptidoglycan contents of the samples were determined by gas chromatography-tandem mass spectrometry analysis of, respectively, 3-hydroxy fatty acids and muramic acid; in addition, ergosterol was monitored for fungal biomass. The inflammatory properties of house dust upon inhalation may be reflected in its high potency to induce cytokine response in lung epithelial cells.

Therapeutic intervention with complement and beta-glucan in cancer

Complement (C) has two major effector systems available for host defense. The membrane attack complex (MAC) generated from components C5-C9 can form membrane-penetrating lesions that lead to cell death by causing a rapid loss of cytoplasmic components. The MAC is only effective against pathogens with outer phospholipid membranes, and cannot kill gram-positive bacteria or yeast whose membranes are protected by cell walls. The most important effector mechanism of C is the opsonization of microbial pathogens with the serum protein C3 that leads to their high avidity attachment to the C3-receptors of phagocytic cells. Pathogens that activate complement are first coated with the C3b fragment of C3, which is rapidly proteolyzed into the iC3b fragment by serum factor I. These iC3b fragments serve to promote the high avidity attachment of the 'iC3b-opsonized' pathogens to the iC3b-receptors (CR3, CD11b/CD18) of phagocytic cells and natural killer (NK) cells, stimulating phagocytosis and/or cytotoxic degranulation. Host cells, including neoplastic tumor cells, have been endowed with natural mechanisms for self-protection against both the MAC and the cytotoxic activation of CR3. This review discusses a novel type of immunotherapy for cancer that uses soluble yeast beta-glucan to override the normal resistance of iC3b-opsonized tumor cells to the cytotoxic activation of phagocyte and NK cell CR3, allowing this important effector mechanism of the C system to function against tumor cells in the same way that it normally functions against bacteria and yeast. Moreover, the cytotoxic activation of beta-glucan-primed NK cell CR3 by iC3b-opsonized tumors is shown to be accompanied by a tumor-localized secretion of the cytokines TNFalpha, IFNalpha, IFNgamma, and IL-6.

Synergistic effects of bovine respiratory syncytial virus and non-cytopathic bovine viral diarrhea virus infection on selected bovine alveolar macrophage functions

The effect of bovine respiratory syncytial virus (BRSV) and non-cytopathic bovine viral diarrhea virus (ncpBVDV) infection on selected bovine alveolar macrophage (AM) functions was investigated. Alveolar macrophages were harvested from 2- to 6-month-old calves seronegative for BRSV and BVDV and inoculated with approximately 1 median cell culture infective dose of virus per AM. Control, BRSV infected, ncpBVDV-infected and BRSV-ncpBVDV coinfected AM cultures were evaluated for Fc receptor expression, phagosome-lysosome fusion, superoxide anion (O2-) production, and chemotactic activity on Days 1, 3, 5, and 7 post-infection. Both single and combined viral infections significantly depressed AM Fc receptor expression, phagosome-lysosome fusion, and secretion of chemotactic factors with a more significant synergistic depression seen in BRSV-ncpBVDV coinfection. Production of O2- by AM was not decreased by either BRSV or ncpBVDV infection, but was significantly decreased by coinfection with BRSV-ncpBVDV. The present study confirms previous reports of BRSV effects on AM functions and indicate that ncpBVDV affects AM functions in vitro. Coinfection with BRSV-ncpBVDV produced a synergistic depression on AM functions.

Evaluation of inflammatory cytokine secretion by human alveolar macrophages

The alveolar macrophage (AM) secretes interleukin 1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8), all of them inflammatory cytokines involved in the pathogenesis of many lung diseases. The aim of the present work was to evaluate the basal and stimulated secretion of these cytokines by human AMs. Human AMs were collected by bronchoalveolar lavage (BAL) from four healthy controls and 13 patients with diffuse interstitial lung disease (five cases of sarcoidosis, three of hypersensitivity pneumonitis and five of idiopathic pulmonary fibrosis). AMs were cultured in the presence or absence of different concentrations of lipopolysaccharide (LPS), phorbolmyristate and gamma-interferon. IL-1beta, TNF-alpha, IL-6 and IL-8 levels were measured in BAL fluid and culture supernatant using specific enzyme-linked immunosorbent assays. The substance found to stimulate the secretion of inflammatory cytokines to the greatest extent was LPS at a concentration of 10 microg/ml. Regarding the secretion of IL-1beta, four observations were of interest: basal secretion was very low; LPS exerted a potent stimulatory effect; considerable within-group variability was observed; and there were no significant differences in the comparisons among groups. With respect to TNF-alpha secretion, the results were similar. The only striking finding was the higher basal secretion of this cytokine with respect to that of IL-1beta. Regarding the secretion of IL-6, the same pattern followed by TNF-alpha was found. However, it should be stressed that the increase induced by LPS was smaller than in the two previous cytokines. Regarding the secretion of IL-8, three findings were patent: the strong basal secretion of this cytokine; the moderate increase induced by LPS; and the existence of significant differences among the different groups with respect to the stimulated secretion of this cytokine, which reached maximum values in patients with idiopathic pulmonary fibrosis. Finally, it should be noted that the pattern of cytokines observed in the BAL fluid was similar to that found in cultured AM supernatants. The pattern of inflammatory cytokine secretion by AMs differs from that of other cells of the mononuclear phagocyte system (MPS). In this sense. AMs secrete low amounts of IL-1, moderate amounts of TNF-alpha and IL-6, and high quantities of IL-8. Adherence is an important stimulus in the secretion of these molecules and LPS elicits an increased secretion inverse to the basal secretion. There is considerable individual variability in the secretion of inflammatory cytokines by the AMs of patients with interstitial lung disease and the AMs of these patients are primed in vivo for the secretion of these cytokines. The results of our study, carried out in vitro, can be extrapolated to the in vivo setting.

Pathogenesis of porcine Actinobacillus pleuropneumonia, part II: roles of proinflammatory cytokines

The in vitro production of proinflammatory cytokines after stimulation with Actinobacillus pleuropneumoniae and the relation of these cytokines in vivo with the disease caused by A. pleuropneumoniae were investigated. Within 24 h, in vitro stimulation by A. pleuropneumoniae (serotype 1) preparations, including killed bacteria, bacterial culture supernatant, lipopolysaccharide, and bacterial extracts, porcine pulmonary alveolar macrophages (PAM) produced significant (P < 0.05) amounts of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) as measured by bioassays. The supernatants containing interleukin-8 from PAM after stimulation by bacterial preparations showed significant neutrophil chemotaxis, while bacterial preparations alone did not. After in vivo infection with A. pleuropneumoniae, the mean levels of TNF-alpha and IL-1 in serum, as measured by bioassays, were elevated 37- to 27836-fold for TNF-alpha and 11- to 5941-fold higher for IL-1 within 4 d post-infection, depending on the treatments, and remained elevated up to Day 7. Both cytokines were also detected in porcine lungs by bioassays and immunocytochemistry. The results indicated that both secreted and surface components of A. pleuropneumoniae can stimulate PAM to produce proinflammatory mediators. Neutrophil chemoattractants rather than bacterial components are the major factor causing acute lung inflammation. The elevation of TNF-alpha and IL-1 in pigs occurred coincident with the onset of acute clinical disease.

The correlation of gingival crevicular fluid interleukin-8 levels and periodontal status in localized juvenile periodontitis

Localized juvenile periodontitis (LJP) is an early-onset periodontal disease characterized by progressive bone loss involving the permanent first molar and incisor teeth. Approximately 70% to 75% of LJP patients have impaired neutrophil chemotaxis towards a number of chemoattractants including N-formyl-methionyl-leucyl-phenyl-alanine, complement fragment C5a, leukotriene B4, and interleukin 8 (IL-8). The aim of the present study was to observe the role of IL-8 in the pathogenesis of LJP. Fourteen individuals who were systemically and periodontally healthy and 24 systemically healthy individuals diagnosed with LJP (based on the results of clinical periodontal assessments and radiographic examination) were recruited for this study. Gingival crevicular fluid (GCF) samples were obtained from anterior teeth in each subject before treatment. After evaluation of GCF amount from paper strips, enzyme-linked immunoabsorbent assay was employed to determine the amount of IL-8 in GCF. The amount and concentration of IL-8 measured was 894.5 +/- 435 pg, and 445.3 +/- 468 pg/microl for the experimental group and 747.3 +/- 543 pg and 684.7 +/- 548 pg/microl, for the control group. The correlation among the levels of cytokine and clinical parameters was assessed. It was observed that the concentration of IL-8 demonstrated a negative correlation with gingival index in the LJP group. In addition, no significant correlation was found among the total amount and concentration of IL-8, GCF volume, and clinical parameters in the control group. IL-8 is thought to enhance host defense mechanisms against gram-negative bacteria, thus providing protection against periodontal infections. Our data demonstrate that, when both the total amount and concentration of IL-8 are taken into consideration, no significant difference between LJP and healthy subjects is shown. This may indicate a less active IL-8 production compared with healthy subjects in spite of the dense Gram bacterial stimulation in LJP.

Quantitative comparison of C-X-C chemokines produced by endotoxin-stimulated human alveolar macrophages

The C-X-C chemokines are a structurally related and functionally redundant family of proteins with neutrophil chemotactic activity. Many of the C-X-C chemokines are produced by endotoxin-stimulated alveolar macrophages (AMs), but knowledge of their relative quantities and their relative contributions to the total chemotactic activity released from these cells is incomplete. Human AMs were stimulated with or without Escherichia coli endotoxin for 2, 4, 8, and 24 h. The mRNA sequences of interleukin (IL)-8, the 78-amino acid epithelial cell-derived neutrophil activator (ENA-78), growth-related protein (GRO) alpha, GRObeta, and GROgamma were cloned by PCR and identified by sequence analysis. The relative mRNA quantities were compared by Northern analysis, and IL-8 was found to predominate. Similarly, IL-8 protein concentrations in the cell supernatants were consistently higher than either the ENA-78 or GRO concentration, and by 24 h, IL-8 concentrations were 10-fold higher than those of the other C-X-C chemokines. Blocking polyclonal antibodies to IL-8 substantially reduced the chemotactic activity in the AM supernatants, whereas antibodies to ENA-78 and GRO had little or no effect. We conclude that IL-8 is the predominant C-X-C chemokine and the dominant neutrophil chemoattractant accumulating in 24-h supernatants of lipopolysaccharide-stimulated human AMs. These studies provide insight into potentially effective strategies of interrupting AM-derived inflammatory signals in the lungs.

Induction of IL-8 production in human alveolar macrophages and human bronchial epithelial cells in vitro by swine dust

BACKGROUND

Exposure to swine dust causes an intense airway inflammation with increased levels of interleukin 8 (IL-8) and predominantly neutrophils in the nasal and bronchoalveolar lavage fluids of healthy human subjects. It is not clear which components in the swine house environment are responsible for the airway reaction. The aim of the present study was to evaluate and compare the effect in vitro of swine dust components on human alveolar macrophages and bronchial epithelial cells.

METHODS

Normal human bronchial epithelial cells (NHBE), human pulmonary epithelial carcinoma cell line (A549), and human alveolar macrophages were stimulated with swine dust, lipopolysaccharides (LPS; present in Gram negative bacteria), grain dust (swine feed components), and glucans (a structural component of fungi) in a dose response manner (1-100 micrograms/ml).

RESULTS

Swine dust at a concentration of 100 micrograms/ml increased IL-8 production 20 fold in NHBE cells, 28 fold in A549 cells, and 15 fold in macrophages. LPS (100 micrograms/ml) stimulated all three cell types significantly, in macrophages to the same extent as swine dust, but in NHBE and A549 cells swine dust was 5-8 times as potent. Grain dust (100 micrograms/ml) had no effect in A549 cells and macrophages but not NHBE cells. Both glucans and grain dust were weaker stimuli than swine dust and LPS. The LPS content of swine dust solution was 2.16 (0.2) ng/100 micrograms and of grain dust was 0.53 (0.04) ng/100 micrograms.

CONCLUSIONS

Swine dust is a strong stimulus for IL-8 production in both bronchial epithelial cells and human alveolar macrophages, whereas LPS has different potency in these cells.

Endogenous tumor necrosis factor (TNF) alpha mediates neutrophil accumulation at the mid-phase of a murine model of Pseudomonas aeruginosa pneumonia

To determine the role of endogenous tumor necrosis factor (TNF) alpha on neutrophil influx into the lungs in acute Pseudomonas aeruginosa pneumonia, we evaluated TNF alpha activity, inflammatory cell response and neutrophil chemotactic activity in the bronchoalveolar lavage fluids (BALFs) of P. aeruginosa-infected mice. In the case of fatal pneumonia, the TNF alpha activity in the BALFs appeared within 3 hr, peaked at 6-12 hr and attenuated within 24 hr after intratracheal challenging, while no TNF alpha activity was detected in the plasma. The elevation of TNF alpha activity in the BALFs was closely associated with neutrophil accumulation. Mirroring the TNF alpha activity response and the influx of neutrophils into the murine airway, the number of neutrophils in the BALFs increased within 3 hr, peaked at 6-12 hr and remained elevated up to 24 hr after challenging. Neutralization of the TNF alpha activity in the BALFs with anti-murine TNF antiserum decreased the level of neutrophil migration by BALF 45.0-49.7% at 6 hr and 49.3-54.2% at 12 hr, while the neutralizing antiserum had no effect on the level of neutrophil migration by BALFs at 3 and 24 hr. Furthermore, the intravenous administration of anti-murine TNF antiserum 2 hr before challenging significantly inhibited neutrophil migration into the lungs of mice with sublethal pneumonia (P < 0.05; compared with mice receiving pre-immune serum). These data suggest that intra-alveolar TNF alpha plays an important role in causing lung neutrophil accumulation at the mid-phase of murine P. aeruginosa pneumonia.

Endotoxin priming of thromboxane-related vasoconstrictor responses in perfused rabbit lungs

In prior studies of perfused lungs, endotoxin priming markedly enhanced thromboxane (Tx) generation and Tx-mediated vasoconstriction in response to secondarily applied bacterial exotoxins. The present study addressed this aspect in more detail by employing precursor and intermediates of prostanoid synthesis and performing functional testing of vasoreactivity and measurement of product formation. Rabbit lungs were buffer perfused in the absence or presence of 10 ng/ml endotoxin. Repetitive intravascular bolus applications of free arachidonic acid provoked constant pulmonary arterial pressor responses and constant release reactions of TxA2 and prostaglandin (PG) I2 in nonprimed lungs. Within 60-90 min of endotoxin recirculation, which provoked progressive liberation of tumor necrosis factor-alpha but did not effect any hemodynamic changes by itself, both pressor responses and prostanoid release markedly increased, and both events were fully blocked by cyclooxygenase (Cyclo) inhibition with acetylsalicylic acid (ASA). The unstable intermediate PGG2 provoked moderate pressor responses, again enhanced by preceding endotoxin priming and fully suppressed by ASA. Vasoconstriction also occurred in response to the direct Cyclo product PGH2, again amplified after endotoxin pretreatment, together with markedly enhanced liberation of TxA2 and PGI2. In the presence of ASA, the priming-related increase in pressor responses and the prostanoid formation were blocked, but baseline vasoconstrictor responses corresponding to those in nonprimed lungs were maintained. Pressor responses to the stable Tx analog U-46619 were not significantly increased by endotoxin pretreatment, but some generation of TxA2 and PGI2 was also noted under these conditions. We conclude that endotoxin priming exerts profound effects on the lung vascular prostanoid metabolism, increasing the readiness to react with Tx-mediated vasoconstrictor responses to various stimuli, suggesting that enhanced Cyclo activity is an important underlying event.

Effect of exposure to swine dust on levels of IL-8 in airway lavage fluid

BACKGROUND

Inhalation of swine dust causes airway inflammation with influx of inflammatory cells, predominantly neutrophils, into the lungs. A study was undertaken to determine whether or not exposure to swine dust induces release of interleukin 8 (IL-8) into upper and lower airways and how this possible release is related to cellular influx. A further aim was to study the relationship between the inflammatory response and swine dust exposure.

METHODS

Thirty one healthy, non-smoking, previously unexposed subjects were exposed to swine dust during three hours work in a swine house. Bronchoalveolar lavage (BAL) was performed two weeks before and 24 hours after the exposure (n = 16). Nasal lavage and acoustic rhinometry were carried out 1-2 hours before and seven hours after the start of the exposure (n = 31). Exposure measurements were performed with personal sampling equipment.

RESULTS

The exposure led to 19-fold and 70-fold increases in the neutrophil concentrations in nasal lavage and BAL fluid, respectively (p < 0.001). In BAL, fluid macrophages, lymphocytes and eosinophils increased significantly. The IL-8 levels in BAL fluid increased from < 31.3 ng/l to 63 (43-109) ng/l (median (25-75th percentile), p < 0.001), and in nasal lavage fluid the concentrations increased from 144 (97-227) ng/l to 1064 (864-1437) ng/l (p < 0.001). IL-8 levels showed a significant correlation with the increase in neutrophils in the nasal lavage fluid but not in the BAL fluid. Acoustic rhinometry demonstrated significant swelling of the nasal mucosa. The air concentration of inhalable dust was 23.3 (20.0-29.3) mg/m3, endotoxin 1.3 (1.1-1.4) micrograms/m3, and muramic acid 0.99 (0.78-2.1) microgram/m3.

CONCLUSIONS

The concentration of IL-8 increases in BAL fluid and nasal lavage fluid following exposure to swine dust and may be one of the chemoattractants contributing to the recruitment of neutrophils to the nasal cavity and the alveolar space.

Role of pertussis toxin A subunit in neutrophil migration and vascular permeability

The anti-inflammatory activity of pertussis toxin (Ptx) was compared to that of a noncatalytic mutant of pertussis toxin (9K/129G; Ptxm), which contains two amino acid substitutions in the A protomer, by using a rat model of inflammation. The toxins were administered intravenously 1 h prior to the injection of inflammatory stimuli. Ptx, but not Ptxm, inhibited neutrophil migration into peritoneal cavities in response to formyl-methionyl-leucyl-phenylalanine and lipopolysaccharide. The inhibitory effect of Ptx on neutrophil migration could not be explained by the ability of the toxin to induce leukopenia or neutropenia. The increase in skin vascular permeability induced by leukotriene B4, a powerful neutrophil chemotactic agent, was also inhibited only by Ptx. On the other hand, the increase in skin vascular permeability induced by histamine was potentiated by both toxins. These data show that Ptx inhibits neutrophil-mediated inflammation in vivo and that this effect is dependent on the ADP-ribosyltransferase activity of the A protomer.