ICAM-1 and integrin expression on isolated human alveolar type II pneumocytes

Epithelium-Specific Ets-Like Transcription Factor 1, ESE-1, Regulates ICAM-1 Expression in Cultured Lung Epithelial Cell Lines

Cystic fibrosis (CF) patients suffer from chronic airway inflammation with excessive neutrophil infiltration. Migration of neutrophils to the lung requires chemokine and cytokine signaling as well as cell adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), which plays an important role in mediating adhesive interactions between effector and target cells in the immune system. In this study, we investigated the relationship between ICAM-1 and epithelium-specific ETS-like transcription factor 1 (ESE-1) and found that ICAM-1 expression is upregulated in cell lines of CF (IB3-1) as well as non-CF (BEAS-2B and A549) epithelial origin in response to inflammatory cytokine stimulation. Since ESE-1 is highly expressed in A549 cells without stimulation, we examined the effect of ESE-1 knockdown on ICAM-1 expression in these cells. We found that ICAM-1 expression was downregulated when ESE-1 was knocked down in A549 cells. We also tested the effect of ESE-1 knockdown on cell-cell interactions and demonstrate that the knocking down ESE-1 in A549 cells reduce their interactions with HL-60 cells (human promyelocytic leukemia cell line). These results suggest that ESE-1 may play a role in regulating airway inflammation by regulating ICAM-1 expression.

Serum levels of IL-8 and ICAM-1 as biomarkers for progressive massive fibrosis in coal workers' pneumoconiosis

Coal workers' pneumoconiosis (CWP) is characterized as a chronic inflammation of the lung associated with activation of macrophages and endothelial cells in the lung. The aim of the present study was to compare the levels of serum interleukin-8 (IL-8), macrophage inflammatory protein-1α (MIP-α), and intercellular adhesion molecule-1 (ICAM-1) as biomarkers for progressive massive fibrosis (PMF) in 106 subjects (27 non-CWP and 79 CWP patients). The levels of serum IL-8 (P<0.001) and ICAM-1 (P=0.001) of subjects with PMF were higher than those of non-CWP subjects. The IL-8 levels of PMF subjects were also higher than those of simple CWP subjects (P=0.003). Among the subjects without PMF, IL-8 levels in the subjects with International Labour Organization (ILO) category II or III were higher than those in the subjects with ILO category 0 (P=0.006) and with category I (P=0.026). These results suggest that high serum levels of IL-8 and ICAM-1, which are important as neutrophil attractants and adhesion molecules, are associated with PMF.

Associations among lung function, arterial elasticity, and circulating endothelial and inflammation markers: the multiethnic study of atherosclerosis

A parallel physiological pathway for elastic changes is hypothesized for declines in arterial elasticity and lung function. Endothelial dysfunction and inflammation could potentially decrease elasticity of both vasculature and lung tissue. We examined biomarkers, large arterial elasticity and small arterial elasticity (SAE), and forced vital capacity (FVC) in a period cross-sectional design in the multiethnic study of atherosclerosis, which recruited 1823 women and 1803 men, age range 45 to 84 years, black, white, Hispanic, and Chinese, free of clinically recognized cardiovascular disease. Radial artery tonometric pulse waveform registration was performed and large arterial elasticity and SAE were derived from diastole. Spirometric data and markers of endothelial dysfunction and inflammation (soluble intracellular adhesion molecule-1, fibrinogen, hs-C-reactive protein, and interleukin-6) were obtained. Mean large arterial elasticity was 13.7 ± 5.5 mL/mm Hg × 10 and SAE was 4.6 ± 2.6 mL/mm Hg × 100. Mean FVC was 3192 ± 956.0 mL and forced expiratory volume in 1 second was 2386 ± 734.5 mL. FVC was about 40 ± 5 mL higher per SD of SAE, stronger in men than women. The association was slightly weaker with large arterial elasticity, with no sex interaction. After regression adjustment for demographic, anthropometric, and cardiovascular risk factors, the biomarkers tended to be related to reduced SAE and FVC, particularly in men. These biomarker associations suggest important cardiovascular disease risk alterations that occur concurrently with lower arterial elasticity and lung function. The observed positive association of SAE with FVC and with forced expiratory volume in 1 second in middle-aged to older free-living people is consistent with the hypothesis of parallel physiological pathways for elastic changes in the vasculature and in lung parenchymal tissue.

Alleviation of allergic rhinitis symptoms with Pyeongwee-San extract (KMP6)

CONTEXT

Allergy is characterized by the overreaction of the immune system. Pyeongwee-San is a traditional Korean medicine which has been used for the treatment of the allergic disorder but the mechanism of action is not clear.

OBJECTIVE

To investigate the effect of Pyeongwee-San extract (KMP6) and its component, hesperidin (HES) in the allergic rhinitis (AR) animal model.

METHOD

We sensitized mice on 1, 5, and 14 days by intraperitoneal injections of 100 μg ovalbumin (OVA) emulsified in 20 mg of aluminum hydroxide and we challenged mice with 1.5 mg OVA. Mice received KMP6 and HES before the intranasal OVA challenge for 10 days.

RESULTS

The number of nose rubs after the OVA challenge in the OVA-sensitized mice was significantly higher than that in the OVA-unsensitized mice. The increased number of nose rub was inhibited by the oral administration of KMP6 or HES. The increased levels of IgE and histamine level in serum of the OVA-sensitized mice were reduced by KMP6 or HES administration. The level of interferon-γ was enhanced while the level of IL-4 was reduced on the spleen tissue of the KMP6 or HES-administered AR mice. Inflammatory proteins level was reduced by KMP6 or HES administration in the nasal mucosa tissue of the OVA-sensitized mice. In the KMP6 or HES-administered mice, mast cells and eosinophils infiltration increased by OVA-sensitization was decreased.

CONCLUSION

These results indicate that KMP6 and HES ameliorate the allergic inflammatory reactions such as AR.

Wnt pathway aberrations including autocrine Wnt activation occur at high frequency in human non-small-cell lung carcinoma

Lung cancer is the most common cause of cancer mortality worldwide. Non-small-cell lung carcinomas (NSCLCs), which represent around 80% of lung tumors, exhibit poor prognosis and are usually refractory to conventional chemotherapy. Elucidating the molecular and cellular mechanisms that are dysregulated in NSCLCs may lead to new possibilities for targeted therapy or enhanced efficacy of current therapies. Here we demonstrate Wnt pathway activation in around 50% of human NSCLC cell lines and primary tumors, through different mechanisms, including autocrine Wnt pathway activation involving upregulation of specific Wnt ligands. Downregulation of activated Wnt signaling inhibited NSCLC proliferation and induced a more differentiated phenotype. Together, our findings establish importance of activated Wnt signaling in human NSCLCs and offer the possibility of targeting upregulated Wnt signaling as a new therapeutic modality for this disease.

Association of circulating adhesion molecules with lung function. The CARDIA study

BACKGROUND

Systemic inflammation has been associated with reduced lung function. Adhesion molecules, such as intercellular adhesion molecule (ICAM)-1 and P-selectin, figure importantly in initiating the inflammatory response. We studied the association between ICAM-1 and P-selectin concentrations and lung function in the Coronary Artery Risk Development in Young Adults study.

METHODS

Spirometry testing was conducted at years 5, 10, and 20. ICAM-1 and P-selectin were assayed at year 15.

RESULTS

Complete data were obtained from 2,455 participants. We first predicted year-20 lung function from year-15 ICAM-1 concentration data. After controlling for race, gender, height, age, physical activity, smoking status, alcohol intake, BMI, and asthma status, all taken at year 15, the year-20 FVC was 164 mL higher (p < 0.0001) and FEV(1) was 164 mL higher (p = 0.0003) in the lowest ICAM-1 concentration quartile than the highest ICAM-1 quartile, whereas the FEV(1)/FVC ratio showed no association (p = 0.25). We then predicted the year-15 ICAM-1 concentration from year-5 lung function and change in lung function (year 10 - year 5). The year-15 ICAM-1 concentration was about 13 ng/mL higher in the lowest vs highest quartile of either the year-5 FVC (p = 0.01) or year-5 FEV(1) (p = 0.005). Year-15 ICAM-1 concentration was unrelated to year-5 FEV(1)/FVC ratio. Greater loss in FVC and FEV(1) (year 10 - year 5) also was associated with higher year-15 ICAM-1 concentrations. Associations between P-selectin and lung function followed a similar but weaker pattern to that observed for ICAM-1.

CONCLUSIONS

These data suggest a bidirectional association between circulating adhesion molecules, such as ICAM-1 and P-selectin, and pattern of lung function change in adults.

Adhesion molecules involved in hepoxilin A3-mediated neutrophil transepithelial migration

A common feature underlying active states of inflammation is the migration of neutrophils (PMNs) from the circulation and across a number of tissue barriers in response to chemoattractant stimuli. Although our group has recently established a discreet role for the PMN chemoattractant, hepoxilin A3 (HXA3) in the process of PMN recruitment, very little is known regarding the interaction of HXA3 with PMNs. To characterize further the event of HXA3-induced PMN transepithelial migration, we sought to determine the adhesion molecules required for migration across different epithelial surfaces (T84 intestinal and A549 airway cells) relative to two well-studied PMN chemoattractants, formyl-methionyl-leucyl-phenylalanine (fMLP) and leukotriene B4 (LTB4). Our findings reveal that the adhesion interaction profile of PMN transepithelial migration in response to HXA3 differs from the adhesion interaction profile exhibited by the structurally related eicosanoid LTB4. Furthermore, unique to PMN transepithelial migration induced by gradients of HXA3 was the critical dependency of all four major surface adhesion molecules examined (i.e. CD18, CD47, CD44 and CD55). Our results suggest that the particular chemoattractant gradient imposed, as well as the type of epithelial cell monolayer, each plays a role in determining the adhesion molecules involved in transepithelial migration. Given the complexities of these interactions, our findings are important to consider with respect to adhesion molecules that may be targeted for potential drug development.

Effect of IFN-gamma stimulation on expression of intercellular adhesion molecule-1 (ICAM-1) on alveolar macrophages in patients with non-small cell lung cancer

An impairment of in vitro cytotoxicity and tumoricidal function of alveolar macrophages (AMs) in patients with lung cancer was reported in a number of studies. The aim of our study was to evaluate the expression of intercellular adhesion molecule-1 (ICAM-1) on AMs after stimulation with interferon-gamma (IFN-gamma) in patients with non-small cell lung cancer (NSCLC). The study was performed in 13 patients with NSCLC, 6 patients with various nonmalignant pulmonary diseases, and 6 healthy volunteers. AMs were isolated from bronchoalveolar lavage fluid (BALF) by adherence and then cultured with or without IFN-gamma for 24 h. The expression of ICAM-1 on AMs was analyzed by flow cytometry. Stimulation with IFN-gamma caused increased expression of ICAM-1 on AMs in all studied groups (p < 0.05). The degree of the increase in ICAM-1 expression on AMs after IFN-gamma stimulation was significantly lower in patients with NSCLC compared with healthy volunteers (p = 0.002) or the other patients (p = 0.022). The results suggest impaired reactivity of ICAM-1 expression on AMs after stimulation with IFN-gamma in patients with NSCLC, which might be involved in functional defects of AMs in patients with NSCLC.

Pyocyanin and its precursor phenazine-1-carboxylic acid increase IL-8 and intercellular adhesion molecule-1 expression in human airway epithelial cells by oxidant-dependent mechanisms

Pseudomonas aeruginosa secretes numerous factors that alter host cell function and may contribute to disease pathogenesis. Among recognized virulence factors is the redox-active phenazine pyocyanin. We have recently demonstrated that the precursor for pyocyanin, phenazine-1-carboxylic acid (PCA), increases oxidant formation and alters gene expression in human airway epithelial cells. We report in this work that PCA and pyocyanin increase expression of ICAM-1 both in vivo and in vitro. Moreover, phenazines enhanced cytokine-dependent increases in IL-8 and ICAM-1. Antioxidant intervention studies indicated both similarities and differences between PCA and pyocyanin. The thiol antioxidant N-acetyl cysteine, extracellular catalase, and inducible NO synthase inhibitors inhibited ICAM-1 and IL-8 increases in response to both phenazines. However, pyocyanin was significantly more sensitive to N-acetylcysteine inhibition. Interestingly, hydroxyl radical scavengers inhibited the response to pyocyanin, but not to PCA. These studies suggest that P. aeruginosa phenazines coordinately up-regulate chemokines (IL-8) and adhesion molecules (ICAM-1) by mechanisms that are, at least in part, oxidant dependent. However, results indicate that the mechanisms by which PCA and pyocyanin exert their effects are not identical, and not all antioxidant interventions are equally effective in inhibiting phenazine-mediated proinflammatory effects.

Primary type II alveolar epithelial cells present microbial antigens to antigen-specific CD4+T cells

Type II alveolar epithelial cells (AEC) can produce various antimicrobial and proinflammatory effector molecules. This, together with their abundance and strategic location, suggests a role in host defense against pulmonary pathogens. We report that murine type II AEC, like their human counterparts, express class II major histocompatibility complex (MHC). Using a murine model of pulmonary tuberculosis, we find that type II AEC become activated and have increased cell surface expression of class II MHC, CD54, and CD95 following infection. Type II AEC use the class II MHC pathway to process and present mycobacterial antigens to immune CD4+T cells isolated from mice infected with Mycobacterium tuberculosis. Therefore, not only can type II AEC contribute to the pulmonary immunity by secreting chemokines that recruit inflammatory cells to the lung, but they can also serve as antigen-presenting cells. Although type II AEC are unlikely to prime naïve T cells, their ability to present antigens to T cells demonstrates that they can participate in the effector phase of the immune response. This represents a novel role for type II AEC in the immunological response to pulmonary pathogens.

The airway compartment: chambers of secrets

The adhesion molecule intercellular adhesion molecule-1 (ICAM-1) is known to play a crucial role in lung inflammation such as endotoxin-induced injury. Although ICAM-1 has been characterized on endothelial cells, limited information is available regarding its expression in the epithelial compartment. The present review provides novel views on this aspect.

CD208/dendritic cell-lysosomal associated membrane protein is a marker of normal and transformed type II pneumocytes

Dendritic cell-lysosomal associated membrane protein (DC-LAMP)/CD208, a member of the lysosomal associated membrane protein (LAMP) family, is specifically expressed by human DCs on activation. However, its mouse counterpart could not be detected in mature DCs. The present study demonstrates that DC-LAMP is constitutively expressed by mouse, sheep, and human type II pneumocytes. Confocal and immunoelectron microscopy showed that mouse DC-LAMP protein co-localizes with lbm180, a specific marker for the limiting membrane of lamellar bodies that contain surfactant protein B, as well as with intracellular MHC class II molecules that accumulate in the same organelles. Expression of DC-LAMP was also occasionally detected at the cell surface of type II pneumocytes. Interestingly, human bronchioloalveolar carcinoma tumor cells, which correspond to transformed type II pneumocytes, express DC-LAMP. Similar observations were made in the Jaagsiekte sheep retrovirus-associated ovine pulmonary adenocarcinoma, a model of human bronchioloalveolar carcinoma. This study establishes that DC-LAMP is constitutively expressed in normal type II pneumocytes. Furthermore, DC-LAMP appears to be a marker of transformed type II pneumocytes as well, an observation that may help the study and the classification of human lung adenocarcinomas.

Fibrogenic and inflammatory cytokines modulate mRNA expressions of matrix metalloproteinase-3 and tissue inhibitor of metalloproteinase-3 in type II pneumocytes

BACKGROUND

Imbalance between proteinases and their inhibitors released from alveolar type II pneumocytes may cause development of inflammatory lung diseases.

OBJECTIVES AND METHODS

We examined mRNA expressions of matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinase-3 (TIMP-3) in a cell line (A549) and in primary culture of normal adult human type II pneumocytes using reverse transcription-competitive polymerase chain reaction.

RESULTS

Interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) increased MMP-3 and TIMP-3 expressions in A549 cells in a time- and concentration-dependent manner. IL-1beta mainly augmented MMP-3 expression, while TGF-beta1 mainly augmented TIMP-3 expression. Dexamethasone attenuated both IL-1beta- and TGF-beta1-stimulated expressions of MMP-3 and TIMP-3. Interleukin-10 had no significant effect. Hepatocyte growth factor alone had no effect on constitutive MMP-3 expression or TIMP-3 expression, but it augmented TGF-beta1-stimulated MMP-3 expression. The constitutive expressions were higher in normal type II pneumocytes than in A549 cells, but the regulations were similar.

CONCLUSIONS

These data indicated that the matrix degradation is enhanced by IL-1beta and suppressed by TGF-beta1 via regulations in the balance between MMP-3 and TIMP-3. Further, these regulations were shown to be modulated by glucocorticoids and growth factors.

Immunological dysregulation of lung cells in response to vitamin E deficiency

Vitamin E supplementation exhibits anti-inflammatory properties. In the lung, the beneficial effects of vitamin E supplementation on inflammation and infections are well documented, but potential consequences of alimentary vitamin E deficiency to the immunological status of lung cells are not known. It is unclear if temporary vitamin E deficiency exhibits deleterious consequences or can be compensated for by other cellular antioxidants. To address this question, the alimentary vitamin E supply to rats was modified. We then investigated the effects on major histocompatibility molecule (MHC) class II, cell adhesion molecules, interleukin (IL)10, tumor necrosis factor (TNF)alpha in various lung cells. The constitutive expression of MHC class II, intercellular adhesion molecule (ICAM)-1, L-selectin, alpha5-integrin, and CD 166, was demonstrated by flow cytometry on type II pneumocytes, alveolar macrophages, and on co-isolated lymphocytes. Vitamin E depletion increased ICAM-1 and CD166 on type II cells and macrophages, whereas the expression of L-selectin increased only on macrophages. Furthermore, the vitamin E depletion increased the cellular content and secretion of IL10 in type II cells, but decreased the content and secretion of TNFalpha. Vitamin E depletion decreased the cellular vitamin E content, but did not change the activity of antioxidant enzymes (catalase, superoxide dismutase) and the glutathion (GSH)/oxidized glutathion (GSSG) ratio in alveolar type II cells. The shift of protein kinase C (PKC) from the cytosol to membranes indicates that a PKC-dependent signaling pathway may be involved in the change of the immunological status of type II cells. All these effects were reversed by vitamin E repletion. In summary, these results are clearly compatible with the view that a temporary vitamin E deficiency induces a reversible immunological dysregulation in alveolar type II cells and lung macrophages. This deficiency might predispose the lung to develop acute or chronic inflammation.

Integrin alpha(3)-subunit expression modulates alveolar epithelial cell monolayer formation

We investigated expression of the alpha(3)-integrin subunit by rat alveolar epithelial cells (AECs) grown in primary culture as well as the effects of monoclonal antibodies with blocking activity against the alpha(3)-integrin subunit on AEC monolayer formation. alpha(3)-Integrin subunit mRNA and protein were detectable in AECs on day 1 and increased with time in culture. alpha(3)- and beta(1)-integrin subunits coprecipitated in immunoprecipitation experiments with alpha(3)- and beta(1)-subunit-specific antibodies, consistent with their association as the alpha(3)beta(1)-integrin receptor at the cell membrane. Treatment with blocking anti-alpha(3) monoclonal antibody from day 0 delayed development of transepithelial resistance, reduced transepithelial resistance through day 5 compared with that in untreated AECs, and resulted in large subconfluent patches in monolayers viewed by scanning electron microscopy on day 3. These data indicate that alpha(3)- and beta(1)-integrin subunits are expressed in AEC monolayers where they form the heterodimeric alpha(3)beta(1)-integrin receptor at the cell membrane. Blockade of the alpha(3)-integrin subunit inhibits formation of confluent AEC monolayers. We conclude that the alpha(3)-integrin subunit modulates formation of AEC monolayers by virtue of the key role of the alpha(3)beta(1)-integrin receptor in AEC adhesion.

Lipopolysaccharide induces functional ICAM-1 expression in rat alveolar epithelial cells in vitro

Lipopolysaccharide (LPS)-induced lung inflammation is known to increase pulmonary intercellular adhesion molecule-1 (ICAM-1) expression. In the present study, L2 cells, a cell line of alveolar epithelial cells, were stimulated with LPS, and ICAM-1 expression was studied. ICAM-1 protein on L2 cells peaked at 6 (38% increase; P < 0.01) and 10 (48% increase; P < 0.001) h after stimulation with Escherichia coli and Pseudomonas aeruginosa LPS, respectively. ICAM-1 mRNA expression was markedly increased, with a peak at 2-4 (E. coli) and 4-6 (P. aeruginosa) h. Adherence assays of neutrophils to LPS-stimulated L2 cells showed a threefold increase in adherence (P < 0.001). Pretreatment of the neutrophils with anti-lymphocyte function-associated antigen-1 and anti-Mac-1 antibodies reduced adherence by 54% (P < 0.001). Analysis of immunofluorescence staining for ICAM-1 showed an exclusive apical expression of ICAM-1. These results indicate that LPS upregulates functional active ICAM-1 on the apical part of the membrane in rat pneumocytes.

Corticosteroids inhibit rhinovirus-induced intercellular adhesion molecule-1 up-regulation and promoter activation on respiratory epithelial cells

BACKGROUND

Rhinoviruses are associated with the majority of asthma exacerbations. To date, the pathogenesis of virus-induced asthma exacerbations is still unclear, and no safe effective therapy is available. Intercellular adhesion molecule-1 (ICAM-1) has a central role in inflammatory cell recruitment to the airways in asthma and is the receptor for 90% of rhinoviruses. We have previously shown that rhinovirus infection of lower airway epithelium induces ICAM-1 expression by a transcriptional mechanism that is critically nuclear factor-kappaB-dependent.

OBJECTIVE

The purpose of this study was to investigate the effect of systemic (hydrocortisone [HC], dexamethasone [DM]) and topical (mometasone furoate [MF]) corticosteroids on rhinovirus-induced ICAM-1 up-regulation.

METHODS

Cultured primary bronchial or transformed (A549) respiratory epithelial cells were pretreated with corticosteroids for 16 hours and infected with rhinovirus type 16 for 8 hours. ICAM-1 surface expression was evaluated by flow cytometry. In A549 cells ICAM-1 messenger RNA was evaluated by specific reverse transcription-PCR and promoter activation by chloramphenicol acetyltransferase assay.

RESULTS

We observed inhibition of rhinovirus-induced ICAM-1 up-regulation with corticosteroid pretreatment in both primary bronchial epithelial and A549 cells. In A549 cells systemic and topical corticosteroids demonstrated a dose-dependent inhibition with similar efficacy (inhibitory concentration 50% 10(-10) mol/L, 10(-11) mol/L, and 10(-11) mol/L for HC, DM, and MF respectively). MF also inhibited ICAM-1 messenger RNA induction by rhinovirus infection in a dose-dependent manner. MF completely inhibited rhinovirus-induced ICAM-1 promoter activation. HC, DM, and MF had no direct effect on rhinovirus infectivity and replication in cultured cells.

CONCLUSION

Corticosteroids decrease rhinovirus-induced ICAM-1 up-regulation in respiratory epithelial cells and modulate pretranscriptional mechanisms. This effect may be important for the therapeutic control of virus-induced asthma exacerbations.

Monocyte migration through the alveolar epithelial barrier: adhesion molecule mechanisms and impact of chemokines

Alveolar monocyte influx requires adherence and transmigration through the vascular endothelium, extracellular matrix, and alveolar epithelium. For investigating the monocyte migratory process across the epithelial barrier, we employed both the A549 cell line and isolated human alveolar epithelial cells. Under baseline conditions, spontaneous bidirectional transepithelial monocyte migration was noted, which was dose-dependently increased in the presence of the monocyte chemoattractant protein-1. TNF-alpha stimulation of the alveolar epithelium provoked the polarized apical secretion of monocyte chemoattractant protein-1 and RANTES and up-regulation of ICAM-1 and VCAM-1 expression, accompanied by markedly enhanced transepithelial monocyte traffic in the basal-to-apical direction. Multiple adhesive interactions were noted to contribute to the enhanced monocyte traffic across the TNF-alpha-stimulated alveolar epithelium: these included the beta 2 integrins CD11a, CD11b, CD11c/CD18, the beta 1 integrins very late Ag (VLA)-4, -5, and -6, and the integrin-associated protein CD47 on monocytes, as well as ICAM-1, VCAM-1, CD47, and matrix components on the epithelial side. In contrast, spontaneous monocyte migration through unstimulated epithelium depended predominantly on CD11b/CD18 and CD47, with some additional contribution of VLA-4, -5, and -6. In summary, unlike transendothelial monocyte traffic, for which beta 1 and beta 2 integrins are alternative mechanisms, monocyte migration across the alveolar epithelium largely depends on CD11b/CD18 and CD47 but required the additional engagement of the beta 1 integrins for optimal migration. In response to inflammatory challenge, the alveolar epithelium orchestrates enhanced monocyte traffic to the apical side by polarized chemokine secretion and up-regulation of ICAM-1 and VCAM-1.

In vitro cell culture systems as the basis for an extracorporeal blood purification strategy in multiorgan failure treatment

Multiorgan failure (MOF) based on septic processes is very common but prognostically an extremely severe disease that has to be treated exclusively under intensive care conditions. Extracorporeal blood purification (ECBP) using specific and efficient systems such as the microspheres based detoxification system (MDS) (Artif Organs 1996;20:420) could improve significantly the situation of MOF in terms of the efficient removal of endotoxins as well as key mediators such as tumor necrosis factor alpha (TNF alpha). The purpose of the study was to test the effectiveness of endotoxin and cytokine removal to blunt cellular response. In terms of the in vitro principle methodology, isolated peripheral blood mononuclear cells (PBMC) were incubated with endotoxins and a selective endotoxin adsorbent, which was added at various times (immediately or 30, 60, 120, 240, or 360 min) after the onset of incubation. TNF alpha release of monocytes was measured following a standard procedure after 20 h. Human TNF alpha was incubated with cultured human endothelial cells with and without a specific TNF alpha adsorbent (polyclonal antibodies coated on polystyrene particles). The results showed that after the initial addition of endotoxins, the activation of monocytes can be stopped within 120 min by addition of endotoxin adsorbents. In addition, specific TNF alpha adsorbents are able to prevent intercellular adhesion molecule 1 (ICAM-1) expression of endothelial cells, therefore avoiding activation of endothelial cells. In conclusion, cell culture models are suitable to simulate cell interaction in MOF. Specific adsorbents are able to reduce or block pathophysiologically relevant cell interactions, and the time frame for effective ECBP seems to be very short, and therefore, efficiency must be high.