LPS induces pulmonary intravascular macrophages producing inflammatory mediators via activating NF-kappaB

The role of lung macrophages in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute and diffuse inflammatory lung injury in a short time, one of the common severe manifestations of the respiratory system that endangers human life and health. As an innate immune cell, macrophages play a key role in the inflammatory response. For a long time, the role of pulmonary macrophages in ARDS has tended to revolve around the polarization of M1/M2. However, with the development of single-cell RNA sequencing, fate mapping, metabolomics, and other new technologies, a deeper understanding of the development process, classification, and function of macrophages in the lung are acquired. Here, we discuss the function of pulmonary macrophages in ARDS from the two dimensions of anatomical location and cell origin and describe the effects of cell metabolism and intercellular interaction on the function of macrophages. Besides, we explore the treatments for targeting macrophages, such as enhancing macrophage phagocytosis, regulating macrophage recruitment, and macrophage death. Considering the differences in responsiveness of different research groups to these treatments and the tremendous dynamic changes in the gene expression of monocyte/macrophage, we discussed the possibility of characterizing the gene expression of monocyte/macrophage as the biomarkers. We hope that this review will provide new insight into pulmonary macrophage function and therapeutic targets of ARDS.

Hypoxia Aggravates Inhibition of Alveolar Epithelial Na-Transport by Lipopolysaccharide-Stimulation of Alveolar Macrophages

Inflammation and hypoxia impair alveolar barrier tightness, inhibit Na- and fluid reabsorption, and cause edema. We tested whether stimulated alveolar macrophages affect alveolar Na-transport and whether hypoxia aggravates the effects of inflammation, and tested for involved signaling pathways. Primary rat alveolar type II cells (rA2) were co-cultured with rat alveolar macrophages (NR8383) or treated with NR8383-conditioned media after stimulation with lipopolysaccharide (LPS; 1 µg/mL) and exposed to normoxia and hypoxia (1.5% O2). LPS caused a fast, transient increase in TNFα and IL-6 mRNA in macrophages and a sustained increase in inducible nitric oxide synthase (NOS2) mRNA in macrophages and in rA2 cells resulting in elevated nitrite levels and secretion of TNF-α and IL-6 into culture media. In normoxia, 24 h of LPS treated NR8383 decreased the transepithelial electrical resistance (TEER) of co-cultures, of amiloride-sensitive short circuit current (ISCΔamil); whereas Na/K-ATPase activity was not affected. Inhibition was also seen with conditioned media from LPS-stimulated NR8383 on rA2, but was less pronounced after dialysis to remove small molecules and nitrite. The effect of LPS-stimulated macrophages on TEER and Na-transport was fully prevented by the iNOS-inhibitor L-NMMA applied to co-cultures and to rA2 mono-cultures. Hypoxia in combination with LPS-stimulated NR8383 totally abolished TEER and ISCΔamil. These results indicate that the LPS-stimulation of alveolar macrophages impairs alveolar epithelial Na-transport by NO-dependent mechanisms, where part of the NO is produced by rA2 induced by signals from LPS stimulated alveolar macrophages.

Aspirin Attenuates Hyperoxia-Induced Acute Respiratory Distress Syndrome (ARDS) by Suppressing Pulmonary Inflammation via the NF-κB Signaling Pathway

Acute respiratory distress syndrome (ARDS) is a common destructive syndrome with high morbidity and mortality rates. Currently, few effective therapeutic interventions for ARDS are available. Clinical trials have shown that the effectiveness of aspirin is inconsistent. The contribution of platelets to the inflammatory response leading to the development of ARDS is increasingly recognized. The antiplatelet agent aspirin reportedly exerts a protective effect on acid- and hyperoxia-induced lung injury in murine models. Our previous study showed that pretreatment with aspirin exerts protective effects on hyperoxia-induced lung injury in mice. However, the mechanisms and therapeutic efficacy of aspirin in the posttreatment of hyperoxia-induced acute lung injury (ALI) remain unclear. In this study, we used a homozygous NF-κB-luciferase^+/+ transgenic mouse model and treated mice with low-dose (25 μg/g) or high-dose (50 μg/g) aspirin at 0, 24, and 48 h after exposure to hyperoxia (inspired oxygen fraction (FiO₂) > 95%). Hyperoxia-induced lung injury significantly increased the activation of NF-κB in the lung and increased the levels of macrophages infiltrating the lung and reactive oxygen species (ROS), increased the HO-1, NF-κB, TNF-α, IL-1β, and IL-4 protein levels, and reduced the CC10, SPC, eNOS, Nrp-1, and IκBα protein levels in the lung tissue. Pulmonary edema and alveolar infiltration of neutrophils were also observed in the lung tissue of mice exposed to hyperoxia. However, in vivo imaging revealed that posttreatment with aspirin reduced luciferase expression, suggesting that aspirin might reduce NF-κB activation. Posttreatment with aspirin also reduced hyperoxia-induced increases in the numbers of lung macrophages, intracellular ROS levels, and the expression of TNF-α, IL-1β, and IL-4; it also increased CC10, SPC and Nrp-1 levels compared with hyperoxia exposure alone. Lung histopathology also indicated that the aspirin posttreatment significantly reduced neutrophil infiltration and lung edema compared with hyperoxia exposure alone. Aspirin effectively induces an anti-inflammatory response in a model of hyperoxia-induced lung injury. Thus, aspirin may have potential as a novel treatment for hyperoxia-induced ALI.

Application of α2 -adrenergic agonists combined with anesthetics and their implication in pulmonary intravascular macrophages-insulted pulmonary edema and hypoxemia in ruminants

Alpha₂ -adrenergic agonists have been implicated in the development of pulmonary edema (PE) and sustained hypoxemia that lead to life-threatening pulmonary distress in ruminants, especially with sensitive and compromised animals. Recently, there is limited understanding of exact mechanism underlying pulmonary alterations associated with α₂ -adrenergic agonist administration. Ruminants have a rich population of pulmonary intravascular macrophages (PIMs) in the pulmonary circulation, which may be involved in the development of pulmonary alveolo-capillary barrier damage. Hence, the central thesis of this review is overviewing the literatures regarding the systemic use of α₂ -adrenergic agonists in domestic ruminants, focusing on their pulmonary side effects, especially on the influence of PIMs on the lung. At this moment, further studies are needed to provide a clear emphasis and better understanding of the potential role of PIMs in the lung pathophysiology associated with α₂ -adrenergic agonists. These preliminary studies would be potentially to develop future medications and intervention targets that may be helpful to alleviate or prevent the critical striking pulmonary effects, and thereby improving the safety of α₂ -agonist application in ruminants.

Effects of dexamethasone on hepatic macrophages in normal livers and thioacetamide-induced acute liver lesions in rats

Resident and infiltrative macrophages play important roles in the development of pathological lesions. M1/M2 macrophage polarization with respective CD68 and CD163 expression remains unclear in chemically induced liver injury. This study was aimed at investigating the influence of macrophages on normal and chemically induced liver injury. For this, dexamethasone (DX), an immunosuppressive drug, was administered in normal rats and thioacetamide (TAA)-treated rats. Liver samples were collected and analyzed with immunohistochemical methods. Repeated injections of DX (0.5 or 1.0 mg/kg BW) for 3, 7 and 11 days reduced the number of CD163 positive hepatic resident macrophages (Kupffer cells) in normal livers, while increasing AST and ALT levels. In TAA (300 mg/kg BW)-treated rats injected with DX (0.5 mg/kg BW) pretreatment, the number of M1 and M2 macrophages showed a significant decrease compared with that of TAA-treated rats without DX treatment. Additionally, reparative fibrosis resulting from hepatocyte injury induced by TAA injection was suppressed by DX pretreatment. Our data suggested that macrophages could influence not only normal hepatic homeostasis (reflected by AST and ALT levels) but also chemically induced hepatic lesion development (reduced reparative fibrosis).

Antiplatelet Therapy for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a common and devastating syndrome that contributes to serious morbidities and mortality in critically ill patients. No known pharmacologic therapy is beneficial in the treatment of ARDS, and the only effective management is through a protective lung strategy. Platelets play a crucial role in the pathogenesis of ARDS, and antiplatelet therapy may be a potential medication for ARDS. In this review, we introduce the overall pathogenesis of ARDS, and then focus on platelet-related mechanisms underlying the development of ARDS, including platelet adhesion to the injured vessel wall, platelet-leukocyte-endothelium interactions, platelet-related lipid mediators, and neutrophil extracellular traps. We further summarize antiplatelet therapy, including aspirin, glycoprotein IIb/IIIa receptor antagonists, and P2Y12 inhibitors for ARDS in experimental and clinical studies and a meta-analysis. Novel aspirin-derived agents, aspirin-triggered lipoxin, and aspirin-triggered resolvin D1 are also described here. In this narrative review, we summarize the current knowledge of the role of platelets in the pathogenesis of ARDS, and the potential benefits of antiplatelet therapy for the prevention and treatment of ARDS.

Anti-Inflammatory and Reactive Oxygen Species Suppression through Aspirin Pretreatment to Treat Hyperoxia-Induced Acute Lung Injury in NF-κB-Luciferase Inducible Transgenic Mice

Acute lung injury (ALI), a common cause of morbidity and mortality in intensive care units, results from either direct intra-alveolar injury or indirect injury following systemic inflammation and oxidative stress. Adequate tissue oxygenation often requires additional supplemental oxygen. However, hyperoxia causes lung injury and pathological changes. Notably, preclinical data suggest that aspirin modulates numerous platelet-mediated processes involved in ALI development and resolution. Our previous study suggested that prehospital aspirin use reduced the risk of ALI in critically ill patients. This research uses an in vivo imaging system (IVIS) to investigate the mechanisms of aspirin’s anti-inflammatory and antioxidant effects on hyperoxia-induced ALI in nuclear factor κB (NF-κB)–luciferase transgenic mice. To define mechanisms through which NF-κB causes disease, we developed transgenic mice that express luciferase under the control of NF-κB, enabling real-time in vivo imaging of NF-κB activity in intact animals. An NF-κB-dependent bioluminescent signal was used in transgenic mice carrying the luciferase genes to monitor the anti-inflammatory effects of aspirin. These results demonstrated that pretreatment with aspirin reduced luciferase expression, indicating that aspirin reduces NF-κB activation. In addition, aspirin reduced reactive oxygen species expression, the number of macrophages, neutrophil infiltration and lung edema compared with treatment with only hyperoxia treatment. In addition, we demonstrated that pretreatment with aspirin significantly reduced the protein levels of phosphorylated protein kinase B, NF-κB and tumor necrosis factor α in NF-κB–luciferase^+/+ transgenic mice. Thus, the effects of aspirin on the anti-inflammatory response and reactive oxygen species suppressive are hypothesized to occur through the NF-κB signaling pathway. This study demonstrated that aspirin exerts a protective effect for hyperoxia-induced lung injury and thus is currently the drug conventionally used for hyperoxia-induced lung injury.

Use of non-steroidal anti-inflammatory drugs in porcine health management

OBJECTIVE

Treatment of inflammation and pain management is an important topic in the welfare of pigs. It is very difficult for veterinary practitioners to choose the most appropriate product for a certain problem. This review aims to summarise and discuss the characteristics of different non-steroidal anti-inflammatory drugs (NSAIDs), as well as paracetamol and metamizole, available for pigs in the European Union.

METHODS

The databases Pubmed, Google Scholar, CliniPharm CliniTox and European Medicines Agency were searched. Relevant terms (eg,'meloxicam', 'fever', 'swine', 'pig', 'inflammation', 'castration', 'pain') were used to search for original articles, reviews and books. Only peer-reviewed articles were used. References from studies were also analysed in order to find additional relevant studies.

CONCLUSION

Studies which have investigated the efficacy of NSAIDs for different conditions, using different treatment regimens, are scarce. Most studies focused on the efficacy of NSAID-related pain alleviation in piglet castration, as well as the anti-inflammatory potential of NSAIDs in experimental inflammation models. Little research has been carried out on the use of metamizole, tolfenamic acid, paracetamol and sodium salicylate and their effect in pigs.

Porcine Alveolar Macrophage-like cells are pro-inflammatory Pulmonary Intravascular Macrophages that produce large titers of Porcine Reproductive and Respiratory Syndrome Virus

Lung inflammation is frequently involved in respiratory conditions and it is strongly controlled by mononuclear phagocytes (MNP). We previously studied porcine lung MNP and described a new population of cells presenting all the features of alveolar macrophages (AM) except for their parenchymal location, that we named AM-like cells. Herein we showed that AM-like cells are macrophages phagocytosing blood-borne particles, in agreement with a pulmonary intravascular macrophages (PIM) identity. PIM have been described microscopically long time ago in species from the Laurasiatheria superorder such as bovine, swine, cats or cetaceans. We observed that PIM were more inflammatory than AM upon infection with the porcine reproductive and respiratory syndrome virus (PRRSV), a major swine pathogen. Moreover, whereas PRRSV was thought to mainly target AM, we observed that PIM were a major producer of virus. The PIM infection was more correlated with viremia in vivo than AM infection. Finally like AM, PIM-expressed genes were characteristic of an embryonic monocyte-derived macrophage population, whose turnover is independent of bone marrow-derived hematopoietic precursors. This last observation raised the interesting possibility that AM and PIM originate from the same lung precursor.

Morphologic Characteristics of Pulmonary Macrophages in Cetaceans: Particular Reference to Pulmonary Intravascular Macrophages as a Newly Identified Type

We examined the morphologic characteristics of pulmonary macrophages in 42 specimens of Odontoceti ( Globicephala macrorhynchus, Grampus griseus, Tursiops truncatus, Stenella attenuata, Stenella coeruleoalba, Berardius bairdii), using light and electron microscopes as well as immunohistochemistry with SRA-E5. SRA-E5-positive alveolar macrophages and pulmonary interstitial macrophages contained graphitic soots, indicating the clearance of airborne, aspirated foreign bodies. Pulmonary intravascular macrophages (PIMs), positive with SRA-E5, were present within pulmonary capillaries, attaching to applied endothelial cells by cell junctions. They showed cytoplasmic tubular structures of micropinocytosis vermiformis and erythrophagocytosis, indicating their contributory role in the clearance of blood-borne particles. The uptake of pathogens by PIMs may be associated with the inducement of acute lung injury, especially bacterial infectious pneumonia. This study revealed for the first time the presence of PIMs in cetaceans.

Prehospital aspirin use is associated with reduced risk of acute respiratory distress syndrome in critically ill patients: a propensity-adjusted analysis

OBJECTIVES

Platelet activation plays an active role in the pathogenesis of acute respiratory distress syndrome. In our prior study of 575 patients at high risk for acute respiratory distress syndrome, concurrent statin and aspirin use was associated with reduced acute respiratory distress syndrome. However, the largest study (n = 3,855) to date found no significant benefit of prehospital aspirin in a lower-risk population when adjusted for the propensity for aspirin use. We aimed to determine whether prehospital aspirin use is associated with decreased acute respiratory distress syndrome in patients at high risk for acute respiratory distress syndrome after adjusting for the propensity to receive aspirin.

DESIGN

Secondary analysis of patients enrolled prospectively in the Validating Acute Lung Injury Markers for Diagnosis study.

PATIENTS

A total of 1,149 critically ill patients (≥40 years old) admitted to the medical or surgical ICUs of an academic tertiary care hospital including 575 previously reported patients as well as additional patients who were enrolled after completion of the prior statin and aspirin study.

INTERVENTION

None.

MEASUREMENTS AND RESULTS

Of 1,149 patients, 368 (32%) developed acute respiratory distress syndrome during the first 4 ICU days and 287 (25%) patients had prehospital aspirin use. Patients with prehospital aspirin had significantly lower prevalence of acute respiratory distress syndrome (27% vs 34%; p=0.034). In a multivariable, propensity-adjusted analysis including age, gender, race, sepsis, and Acute Physiology and Chronic Health Evaluation score II, prehospital aspirin use was associated with a decreased risk of acute respiratory distress syndrome (odds ratio, 0.66; 95% CI, 0.46-0.94) in the entire cohort and in a subgroup of 725 patients with sepsis (odds ratio, 0.60; 95% CI, 0.41-0.90).

CONCLUSIONS

In this selected cohort of critically ill patients, prehospital aspirin use was independently associated with a decreased risk of acute respiratory distress syndrome even after adjusting for the propensity of prehospital aspirin use. These findings support the need for prospective clinical trials to determine whether aspirin may be beneficial for the prevention of clinical acute respiratory distress syndrome.

Quantitative Assessment of Inflammation in a Porcine Acute Terminal Ileitis Model: US with a Molecularly Targeted Contrast Agent

PURPOSE

To evaluate the feasibility and reproducibility of ultrasonography (US) performed with dual-selectin-targeted contrast agent microbubbles (MBs) for assessment of inflammation in a porcine acute terminal ileitis model, with histologic findings as a reference standard.

MATERIALS AND METHODS

The study had institutional Animal Care and Use Committee approval. Acute terminal ileitis was established in 19 pigs; four pigs served as control pigs. The ileum was imaged with clinical-grade dual P- and E-selectin-targeted MBs (MBSelectin) at increasing doses (0.5, 1.0, 2.5, 5.0, 10, and 20 × 10(8) MB per kilogram of body weight) and with control nontargeted MBs (MBControl). For reproducibility testing, examinations were repeated twice after the MBSelectin and MBControl injections. After imaging, scanned ileal segments were analyzed ex vivo both for inflammation grade (by using hematoxylin-eosin staining) and for expression of selectins (by using quantitative immunofluorescence analysis). Statistical analysis was performed by using the t test, intraclass correlation coefficients (ICCs), and Spearman correlation analysis.

RESULTS

Imaging signal increased linearly (P < .001) between a dose of 0.5 and a dose of 5.0 × 10(8) MB/kg and plateaued between a dose of 10 and a dose of 20 × 10(8) MB/kg. Imaging signals were reproducible (ICC = 0.70), and administration of MBSelectin in acute ileitis resulted in a significantly higher (P < .001) imaging signal compared with that in control ileum and MBControl. Ex vivo histologic grades of inflammation correlated well with in vivo US signal (ρ = 0.79), and expression levels of both P-selectin (37.4% ± 14.7 [standard deviation] of vessels positive; P < .001) and E-selectin (31.2% ± 25.7) in vessels in the bowel wall of segments with ileitis were higher than in control ileum (5.1% ± 3.7 for P-selectin and 4.8% ± 2.3 for E-selectin).

CONCLUSION

Quantitative measurements of inflammation obtained by using dual-selectin-targeted US are reproducible and correlate well with the extent of inflammation at histologic examination in a porcine acute ileitis model as a next step toward clinical translation.

Effect of siRNA against NF-κB on sepsis‑induced acute lung injury in a mouse model

The aim of the present study was to explore the protective effect of small interfering RNA (siRNA) against nuclear factor κB (NF-κB) p65 on sepsis-induced acute lung injury (ALI) in mice. In total, 70 male Kunming mice were randomly divided into a healthy control group, a sepsis group, a specific interfering group and a scrambled control group (Sc), and the latter three groups were divided into post-operational 6 and 12 h subgroups, each of which consisted of 10 mice. The mice were administered with NF-κB siRNA, scrambled siRNA and normal saline via tail vein injection. Following 1 h, a mouse model of septic ALI was produced by cecal ligation and puncture (CLP) in the two siRNA groups and the sepsis control group. At 6 and 12 h post-operation, the experimental mice were sacrificed and the lung tissue samples were collected. Histopathological changes, wet/dry ratio of lung weight, NF-κB protein and NF-κB p65 mRNA levels, matrix metalloproteinase-9 (MMP-9) mRNA and protein activity were detected. Compared with the sepsis group and the Sc at the corresponding time, the expression levels of NF-κB p65 mRNA, the lung injury of experimental mice, the wet/dry ratio and the levels of MMP-9 mRNA and protein activity decreased, and significant differences were observed at 6 h post-operation (P<0.05). RNA interference against NF-κB p65 was able to decrease the expression of NF-κB and further inhibit the early phasic excessive inflammatory reaction in sepsis, which may alleviate ALI.

Pulmonary intravascular macrophages and lung health: what are we missing?

Pulmonary intravascular macrophages (PIMs) are constitutively found in species such as cattle, horse, pig, sheep, goat, cats, and whales and can be induced in species such as rats, which normally lack them. It is believed that human lung lacks PIMs, but there are previous suggestions of their induction in patients suffering from liver dysfunction. Recent data show induction of PIMs in bile-duct ligated rats and humans suffering from hepato-pulmonary syndrome. Because constitutive and induced PIMs are pro-inflammatory in response to endotoxins and bacteria, there is a need to study their biology in inflammatory lung diseases such as sepsis, asthma, chronic obstructive pulmonary diseases, or hepato-pulmonary syndrome. We provide a review of PIM biology to make an argument for increased emphasis and better focus on the study of human PIMs to better understand their potential role in the pathophysiology and mechanisms of pulmonary diseases.

Transfection of hairpin small interfering RNA expression vector targeting rat nuclear factor (NF) (κB) inhibits rat cell proliferation induced by NF-κB signal pathway activation

OBJECTIVE

The aim of this work was to construct one small interfering RNA (siRNA) eukaryotic expression vector targeting rat nuclear factor (NF)κB p65 and identify its inhibition effect on cell proliferation according to its down-regulation of NF-κB pathway.

METHODS

The p65siRNA expression vector "pGenesil-1.2-p65siRNA" and negative control plasmid "HK" were transfected into the cultured rat cells. After transfection, cells were divided into 4 treatment groups: 1) control cells cultured in complete. Dulbecco modified Eagle medium; 2) lipopolysaccharide (LPS) (1 μg/mL); (3) LPS (1 μg/mL) + HK-transfected; 4) LPS (1 μg/mL) + p65siRNA (pGenesil-1.2-p65siRNA). Thereafter, the protein levels of NF-κB p65 in the cells were detected by Western blotting at 72 hours after LPS stimulation. Furthermore, to observe cell proliferation, the proliferative rate of the cell growth was evaluated by the methylthiazolyl tetrazolium assay (at 24, 48, and 72 hours). The cell cycle distribution at 72 hours was detected by flow cytometry.

RESULTS

p65siRNA effectively down-regulated the protein level of p65 (P < .05). Meanwhile, the proliferation of cells transfected with p65siRNA expression vector was significantly inhibited (P < .05), the ratio of cells at G(0)/G(1) stage markedly increased, and the proportion of cells at S stage was significantly decreased among transfected compared with control cells (P < .05).

CONCLUSIONS

p65siRNA effectively suppressed NF-κB, expression, inhibiting rat cell proliferation induced by NF-κB signal pathway activation.

IN VIVO COMPARISON OF CAT ALVEOLAR AND PULMONARY INTRAVASCULAR MACROPHAGES: PHAGOCYTOSIS, PARTICLE CLEARANCE, AND CYTOPLASMIC MOTILITY

The phagocytic and particle clearance function as well as the intracellular motility of cat pulmonary intravascular macrophages (PIMs) and pulmonary alveolar macrophages (PAMs) in situ were compared using ferrimagnetic gammaFe2O3 tracer particles and magnetometry. Submicrometric particles were injected intravenously (phagocytized by PIMs) or inhaled as respirable aerosols (phagocytized by PAMs). At various times post administration, the particles were magnetized with an external magnet. Then, the rate of decay of the remanent magnetic field (relaxation) reflecting the motion of particle-containing phagosomes was measured. There was a gradual increase in relaxation in PAMs, but a decrease in PIMs over the initial 7 hours, suggesting differences in rates of phagocytosis. From 7 to 42 days, relaxation parameters were constant in both cell types although faster in PAMs than in PIMs. Disappearance of retained particles in PIMs depended on the administered dose. Particles in PAMs cleared faster than particles in PIMs. Particle clearance from PIMs, but not from PAMs, was accompanied by translocation of particles to the liver and elsewhere. Our data show that PAMs have a slower rate of in vivo phagocytosis, higher cell motility, and faster particle clearance than PIMs.

Methyl palmitate prevents CCl(4)-induced liver fibrosis

Liver fibrosis is characterized by an excess of collagen fiber deposition, and it is known that Kupffer cells play an important role by immunomodulation of the toxic response. Methyl palmitate (MP) is an effective Kupffer cell inhibitor. The aim of this work was to evaluate the effect of MP on experimental liver fibrosis. Four groups were formed: the control group, which received the vehicles only; CCl(4) group (0.4 g kg(-1), i.p., three times a week, for eight weeks); CCl(4) plus MP (300 mg kg(-1), i.p., daily); and MP alone. Alanine aminotransferase was increased by CCl(4), and MP did not prevent this increase. Lipid peroxidation was increased markedly by CCl(4); again, MP was not able to prevent this effect. Fibrosis increased nearly 6-fold (measured as liver hydroxyproline content) in the CCl(4) group; MP preserved the normal content of collagen. These results were corroborated by histopathology. To elucidate the antifibrogenic mechanism of MP, we measured the production of TGF-beta; CCl(4) increased this cytokine several-fold, and MP abolished this increase. Collectively the present results indicate that MP possesses a strong antifibrogenic effect at least in the CCl(4) model of fibrosis. The antifibrotic effect of MP is probably associated with its ability to reduce TGF-beta content, maybe by immunomodulation of Kupffer cells functioning.

Corticosteroid-resistant asthma is associated with classical antimicrobial activation of airway macrophages

BACKGROUND

The cause of corticosteroid-resistant (CR) asthma is unknown.

OBJECTIVE

We sought to perform gene microarray analyses by using bronchoalveolar lavage (BAL) cells from well-characterized subjects with CR asthma and subject with corticosteroid-sensitive (CS) asthma to elucidate the differential expression of genes that contribute to the development of corticosteroid resistance.

METHODS

The patients were characterized as having CR or CS asthma based on FEV(1) percent predicted improvement after a 1-week course of oral prednisone. Expression of selected gene targets was verified by means of real-time PCR and ELISA.

RESULTS

Microarray analyses demonstrated significantly higher levels (>3-fold increase, P < .05) of transcripts for TNF-alpha, IL-1 alpha, IL-1 beta, IL-6, CXCL1, CXCL2, CXCL3, CXCL8 (IL-8), CCL3, CCL4, and CCL20 in BAL cells of subjects with CR asthma. These findings, confirmed by means of RT-PCR in additional BAL samples, were consistent with classical macrophage activation by bacterial products. In contrast, markers of alternatively activated macrophages, arginase I and CCL24, were decreased. Genes associated with activation of the LPS signaling pathway (early growth response 1, dual-specificity phosphatase 2, molecule possessing ankyrin repeats induced by LPS, and TNF-alpha-induced protein 3) were significantly increased in BAL samples from subjects with CR asthma (P < .05). These patients had significantly higher amounts (1444.0 +/- 457.3 pg/mg total protein) of LPS in BAL fluid than seen in subjects with CS asthma (270.5 +/- 216.0 pg, P < .05), as detected by using the LAL assay and confirmed by means of gas chromatographic/mass spectrometric analysis. Prolonged exposure to LPS induced functional steroid resistance to dexamethasone in normal human monocytes, as demonstrated by persistently increased IL-6 levels in the presence of dexamethasone.

CONCLUSIONS

Classical macrophage activation and induction of LPS signaling pathways along with high endotoxin levels detected in BAL fluid from subjects with CR asthma suggest that LPS exposure might contribute to CR asthma.

Methyl palmitate inhibits lipopolysaccharide-stimulated phagocytic activity of rat peritoneal macrophages

Macrophages, in general, are critical effectors of body's immune system. Chemical inhibition of phagocytic activity of such macrophages as Kupffer cells has been extensively studied. We have earlier shown that methyl palmitate (MP) inhibits the activation of Kupffer cells. To evaluate the potential of MP to inhibit the activation of other macrophages, we treated rat peritoneal macrophages with varying concentrations of MP. Its treatment led to a dose-dependent inhibition of phagocytic activity, which was found to be 34%, 47%, and 66% at 0.25, 0.50, and 1.0 mM MP, respectively, as measured by latex bead uptake. When MP-treated peritoneal macrophages were stimulated with lipopolysaccharide (LPS), the nitric oxide (.NO) release was inhibited at 6 h, while cyclooxygenase-2 expression decreased after 24 h. The treatment with MP increased the release of interleukin (IL)-10 in the LPS-treated cells at 6 h, while IL-6 and tumor necrosis factor-alpha were significantly increased both at 6 and 24 h. Our data suggest that MP inhibits phagocytic activity and .NO production similar to that observed in isolated Kupffer cells. Therefore, inhibition of phagocytosis by MP may be a general phenomenon, and it could be used as an inhibitor of macrophage function.

Aryl hydrocarbon receptor-deficient mice develop heightened inflammatory responses to cigarette smoke and endotoxin associated with rapid loss of the nuclear factor-kappaB component RelB

The transcription factor aryl hydrocarbon receptor (AhR) plays an important role in the response to environmental pollutants. However, its role in normal physiology is unclear. To investigate the role of AhR in acute lung inflammation, control and AhR knockout (KO) mice were exposed to inhaled cigarette smoke or bacterial endotoxin. Smoke-induced lung inflammation was twofold to threefold more severe in AhR KO mice than controls. Intriguingly, levels of tumor necrosis factor-alpha and interleukin-6 in the bronchoalveolar lavage of air-exposed KO mice were equal to the levels seen in smoke-exposed controls, suggesting that AhR-deficient mice are inflammation prone. AhR KO mice challenged with inhaled endotoxin, which does not contain AhR ligands, also developed greater lung neutrophilia than controls, and bronchoalveolar lavage cells from AhR KO mice produced elevated levels of tumor necrosis factor-alpha and interleukin-6 when treated with endotoxin in vitro. Nuclear factor-kappaB DNA-binding activity was elevated in smoke-exposed AhR KO mice compared with controls and was associated with a rapid loss of RelB only in the KO mice. We propose that AhR is a previously unrecognized regulator of inflammation that interacts with nuclear factor-kappaB so that in the absence of AhR RelB is prematurely degraded, resulting in heightened inflammatory responses to multiple proinflam-matory stimuli.

Effects of 15-deoxy-Δ12,14-prostaglandin-J2 during hyperdynamic porcine endotoxemia

OBJECTIVE

To investigate the hemodynamic and metabolic effects of the peroxisome proliferator-activated receptor (PPAR)-gamma ligand and nuclear-factor (NF)-kappa B inhibitor 15-deoxy-Delta12,14-prostaglandin-J2 (15d-PGJ2) during long-term, hyperdynamic porcine endotoxemia.

DESIGN

Prospective, randomized, controlled experimental study with repeated measures.

SETTING

Investigational animal laboratory.

SUBJECTS

19 anesthetized, mechanically ventilated and instrumented pigs.

INTERVENTIONS

At 12 h of continuous intravenous endotoxin and hydroxyethylstarch to keep mean arterial pressure (MAP)>60 mmHg, swine randomly received vehicle (control group, n=10) or 15-deoxy-Delta12,14-prostaglandin-J2 (15d-PGJ2 group, n=9; 1 microg kg(-1) min(-1) loading dose during 1 h; thereafter,0.25 microg kg(-1) min(-1) for 11 h).

MEASUREMENTS AND RESULTS

Hemodynamic, metabolic and organ function parameters were assessed together with parameters of nitric oxide production and oxidative stress. 15d-PGJ2 prevented the endotoxin-induced progressive hypotension, due to a positive inotropic effect, which resulted in a significantly higher blood pressure during the treatment phase and prevented the rise in hepatic vein alanine-aminotransferase activity. It did not affect, however, any other parameter of organ function nor of nitric oxide production, proinflammatory cytokine release or lipid peroxidation (8-isoprostane).

CONCLUSIONS

15d-PGJ2 stabilized systemic hemodynamics, due to improved myocardial performance, and resulted in an only transient effect on alanine-aminotransferase activity, without further beneficial effect on endotoxin-induced metabolic and organ function derangements. Low tissue 15d-PGJ2 concentrations and/or the delayed drug administration may explain these findings.

Inhibition of SRC tyrosine kinases suppresses activation of nuclear factor-kappaB, and serine and tyrosine phosphorylation of IkappaB-alpha in lipopolysaccharide-stimulated raw 264.7 macrophages

Involvement of protein tyrosine kinases (PTK) in lipopolysaccharide (LPS)-induced nuclear factor-kappa B (NF-kappaB) activation has been demonstrated. Studies investigated the role of PTK and the underlying mechanisms by which PTK play a role in LPS induction of pathways leading to NF-kappaB activation in macrophages. Inhibitors of PTK-genistein, herbimycin A, or AG126-blocked LPS-induced NF-kappaB activation. Genistein also blocked pervanadate-induced NF-kappaB activation. Furthermore, Src TK selective inhibitors-damnacanthal or PP1-blocked LPS-induced NF-kappaB activation over a range of nanomolar concentrations. Genistein, damnacanthal, or PP1 blocked the LPS-induced serine phosphorylation, the degradation of IkappaB-alpha, and the consequent translocation of the p65 subunit of NF-kappaB to the nucleus. In addition to serine phosphorylation of IkappaB-alpha, LPS-induced NF-kappaB activation also required tyrosine phosphorylation of IkappaB-alpha. These TK inhibitors blocked substantially LPS induction of tyrosine phosphorylation of IkappaB-alpha. Furthermore, cSrc and Lck were physically associated with IkappaB-alpha. These results suggest that the LPS-induced NF-kappaB pathways are dependent on both serine and tyrosine phosphorylation of IkappaB-alpha, and that Src TK, such as cSrc and Lck, are key components of the LPS signaling pathway through at least two different mechanisms associated with NF-kappaB activation.

Interleukin-17 and lipopolysaccharides synergistically induce cyclooxygenase-2 expression in human intestinal myofibroblasts

BACKGROUND

Colonic subepithelial myofibroblasts (SEMF) play a role in the modulation of mucosal inflammatory responses via the secretion of various inflammatory mediators. In the present study the effects of interleukin (IL)-17 and lipopolysaccharides (LPS) on cyclooxygenase (COX) expression in colonic SEMF were investigated.

METHODS

The expression of COX-1 and -2 proteins and mRNAs were determined by western and northern blotting, respectively. Nuclear factor (NF)-kappaB DNA binding activities were evaluated by electrophoretic gel mobility shift assays (EMSA).

RESULTS

The expression of COX-2 protein and mRNA was rapidly induced by the addition of IL-17 and LPS, whereas COX-1 expression was not affected by these factors. The effects of IL-17 and LPS were detected in a dose- and time-dependent manner. Furthermore, IL-17 and LPS synergistically induced COX-2 mRNA and protein expression. The EMSA demonstrated that the addition of IL-17 and LPS induced NF-kappaB activation within 1.5 h after stimulation, and a blockade of NF-kappaB activation by a recombinant adenovirus containing a stable form of IkappaBa markedly reduced the IL-17- and LPS-induced COX-2 mRNA expression. In these cells, the expression of Toll-like receptor (TLR)-4, which is a cellular receptor for LPS, was detected.

CONCLUSION

Interleukin-17 and LPS play an important role in the induction of COX-2 in SEMF. These findings suggest that COX-2 expression and prostaglandin synthesis might be regulated by both T-cell-derived factor (IL-17) and bacterial products (LPS) in the inflamed mucosa.

Molecular biology of gastric cancer: Helicobacter infection and gastric adenocarcinoma: bacterial and host factors responsible for altered growth signaling

Gastric cancer remains the second most common cause of cancer-related mortality worldwide. The single most common cause of gastric cancer is chronic infection with the gram-negative microaerophilic spiral bacterium: Helicobacter pylori. Recent advances in this field have identified host factors which predispose to gastric cancer formation via modulation of the host immune response. In addition, recent work has explored bacterial virulence factors which may directly cause tissue damage, and lead to gastric carcinogenesis, as well as factors responsible for enhanced immune response. Environmental factors, long associated with a predilection for gastric cancer, are recognized as modifiers of key growth signalling pathways within the gastric mucosa and as such lead to growth alterations. This review focuses on exploring new advances in our understanding of bacterial factors, host genetic polymorphisms and the interaction between the bacterium and host at the level of the immune response and the regulation of proliferative and apoptotic signal transduction cascades. Modulation of the pivotal balance between cell growth and cell death leads to the formation of gastric adenocarcinoma.