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Byline: I. StAiz (1), A. Slavcev (1), J. Kalanin (1), S. I. Rennard (2) Keywords: macrophages; epithelial cells; phenotype Abstract: Interactions of macrophages with epithelium represent one of the pathways involved in regulating local immune mechanisms. We studied the effect of cell--cell contact with an epithelial monolayer on the phenotype of macrophages. Human monocytes and THP-1 macrophages were co-cultured with monolayers of human bronchial epithelial cells (HBECs), the alveolar type II-like cell line A549, renal adenocarcinoma epithelial cells (RA), and the lung fibroblast strain HFL-1. The expression of CD11b, CD14, CD54, and HLA-DR was measured by immunocytochemistry and flow cytometry and showed epithelial cell induction of CD54 and HLA-DR in monocytes and of all antigens in THP-1 cells. Co-culture with fibroblasts did not change the phenotype of macrophages. Separation by a filter insert inhibited most of the effects. Culture supernatants did not induce prominent phenotypic changes. Cell--cell contacts with epithelium appear to be of importance in regulating the phenotype of macrophages. Author Affiliation: (1) Department of Immunology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (2) Pulmonary and Critical Care Section, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska Article History: Registration Date: 17/10/2004

Byline: C. M. Skold (1,2), Y. Ohkuni (3), X. D. Liu (1), R. Numerof (4), S. I. Rennard (1) Abstract: In the current study, we asked whether mast cells might modulate remodeling of extracellular matrix by affecting fibroblast-mediated contraction of three-dimensional collagen gels. Mast cells and human lung fibroblasts were co-cultured in floating type I collagen gels. The area of the gels was measured by an image analyzer. Mast cells in co-culture augmented fibroblast contractility (P &lt 0.001) in a timeand concentration dependent manner. The tryptase inhibitor bis(5-amidino-2-benzimidazo-lyl)methane (BABIM) were unable to block the augmented fibroblast contractility induced by co-cultured mast cells and tryptase added alone in the culture system had no effect on contractility, suggesting that other mediators besides tryptase might be involved. The amount of collagen in dissolved gels, measured as hydroxyproline, did not change after co-culture indicating that degradation of collagen may not be a major mechanism. Our findings support the hypothesis that the activity of mast cells may drive rearrangement of extracellular matrix and this and could subsequently lead to fibrosis and tissue dysfunction. Author Affiliation: (1) Department of Internal Medicine, Pulmonary and Critical Care Medicine Section, University of Nebraska Medical Center, Omaha, Nebraska (2) Department of Medicine, Division of Respiratory Medicine, Karolinska Hospital, Stockholm, Sweden (3) Division of Internal Medicine, Kameda Medical Center, Kamogawa, Japan (4) Axys Pharmaceutical, San Francisco, California Article History: Registration Date: 17/10/2004

Byline: I. StAiz (1), T. Mio (2), Y. Adachi (2), R. A. Robbins (3), D. J. Romberger (3), S. I. Rennard (2) Abstract: Cytokine networks are important in regulating the traffic of inflammatory cells in the airways. Interleukin-8 (IL-8) released by human bronchial epithelial cells (HBECs) is thought to be of particular importance in attracting neutrophils and monocytes to sites of inflammation. Increased release of IL-8 by HBECs in response to Th-1 cytokines such as TNF alpha and IL-1 beta may be an important pathophysiologic pathway. The present study was designed to explore the role of the Th2 cytokine IL-4 and the functionally related interleukins IL-10, and IL-13 on the regulation of IL-8 release by HBECs. HBECs (passage 4--6) were cultured in LHC9/RPMI and when confluent cells were stimulated in unsupplemented medium LHCD/RPMI by IL-4, IL-10, and IL-13 at 10 ng/ml concentration for all cytokines. TNF alpha stimulation was used as a positive control. After 24 hours supernatants were collected and tested for IL-8 by a sandwich ELISA. Unstimulated HBECs spontaneously released limited amounts of IL-8 (11 +- 1 pM) and significantly increased cytokine production in response to IL-4 (42 +- 1 pM), IL-13 (30 +- 1 pM) and TNF (128 +- 11 pM). Stimulation with IL-10 (11 +- 1 pM) did not change basal production of IL-8. When HBECs were co-stimulated with IL-4 plus TNF, the production of IL-8 was further increased (204 +- 5 pM). In contrast, IL-10 attenuated the effect of TNF during co-stimulation (82 +- 5 pM). IL-13 did not affect the release of IL-8 induced by TNF (111 +- 9 pM). Northern blot analysis of IL-8 mRNA levels showed the highest induction of IL-8 mRNA in HBECs co-stimulated with TNF and IL-4. We conclude from our study that IL-4 directly induces IL-8 release from HBECs and amplifies the release of IL-8 in response to TNF alpha. IL-13 is less active and IL-10 has an inhibitory effect. Airway epithelial cells are able to interact, therefore, with products of both Th1 and Th2 cells with respect to modulating release of IL-8. Author Affiliation: (1) Department of Immunology, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (2) Pulmonary and Critical Care Medicine Section, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (3) Veterans Administration Hospital, Omaha, Nebraska Article History: Registration Date: 30/09/2004

Fibroblast contraction of collagen gels is regarded as a model of wound contraction. Transforming growth factor (TGF)-beta added to such gels can augment contraction consistent with its suggested role as a mediator of fibrotic repair. Since fibroblasts isolated from fibrotic tissues have been suggested to express a "fibrotic phenotype," we hypothesized that TGF-beta exposure may lead to a persistent increase in fibroblasts' contractility. To evaluate this question, confluent human fetal lung fibroblasts were treated with serum-free Dulbecco modified Eagle medium (DMEM), with or without 100 pM [corrected] TGF-beta1, TGF-beta2, or TGF-beta3 for 48 h. Fibroblasts were then trypsinized and cast into gels composed of native type I collagen isolated from rat tail tendons. After 20 min for gelation, the gels were released and maintained in serum-free DMEM. TGF-beta-pretreated fibroblasts caused significantly more rapid gel contraction (52.5+/-0.6, 50.9+/-0.2, and 50.3+/-0.5% by TGF-beta1, -beta2, and -beta3 pretreated fibroblasts, respectively) than control fibroblasts (74.0+/-0.3%, P < 0.01). This effect is concentration dependent (50-200 nM), and all three isoforms had equal activity. The effect of TGF-beta1, however, persisted for only a short period of time following the removal of TGF-beta, and was lost with sequential passage. These observations suggest that the persistent increase in collagen-gel contractility, mediated by fibroblasts from fibrotic tissues, would not appear to be solely due to previous exposure of these cells to TGF-beta.

Remodeling of extracellular matrix involves a number of steps including the recruitment, accumulation, and eventual apoptosis of parenchymal cells as well as the production, organization, and rearrangement of extracellular matrix produced by these cells. The culture of fibroblasts in three-dimensional gels made of type I collagen has been used as a model of tissue contraction which characterizes both wound repair and fibrosis. The current study was designed to determine the effect of initial collagen concentration on the ability of fibroblasts to contract collagen gels and on cell survival. Native type I collagen was extracted from rat tail tendons and used to prepare collagen gels with varying collagen concentrations (0.75-2.0 mg/ml). Human lung fibroblasts (HFL-1) were cast into the gels and cultured in Dulbecco modified Eagle medium with 0.1% fetal calf serum for 2 wk. The gel size, collagen content, and deoxyribonucleic acid (DNA) content were determined. Gels prepared with an initial concentration of 0.75 mg/ml contracted more rapidly and to a smaller final size than gels prepared from 2 mg/ml initial collagen concentration (final size 7.1 versus 36.4% of initial size, P < 0.01). There was no significant degradation of the collagen in the gels under either condition. Hence, the dramatically increased contraction of the lower density gels resulted in a higher final density (P < 0.01). Cell density was estimated from DNA content. In low initial density gels, the final DNA content was significantly less than that in higher initial density gels (0.73 versus 1.88 microg/gel, P < 0.05). This was accompanied by an increased percentage of apoptotic cells at day 14 (43.3 versus 34.1%, P < 0.05). If the gels were maintained in the attached state which largely prevents contraction, apoptosis was significantly reduced, suggesting that contraction rather than matrix composition was a requirement for the increased apoptosis. In summary, these findings indicate that the initial matrix composition can lead to differing outcomes during fibroblast-mediated wound contraction.

In vivo, fibroblasts are distributed in a three-dimensional (3-D) connective tissue matrix. Fibronectin is a major product of fibroblasts in routine cell culture and is thought to regulate many aspects of fibroblast biology. In this context, we sought to determine if the interaction of fibroblasts with a 3-D matrix might affect fibronectin production. To examine this hypothesis, fibronectin production by fibroblasts cultured in a 3-D collagen gel or on plastic dishes was measured by ELISA. Fibroblasts in 3-D gel culture produced more fibronectin than those in monolayer culture. Fibroblasts in 3-D culture produced increasing amounts of fibronectin when the collagen concentration of the gel was increased. The 3-D nature of the matrix appeared to be crucial because plating the fibroblasts on the surface of a plastic dish underneath a collagen gel was not different from plating them on a plastic dish in the absence of collagen. In addition to increased fibronectin production, the distribution of the fibronectin produced in 3-D culture was different from that of monolayer culture. In monolayer culture, more than half of the fibronectin was released into the culture medium. In 3-D culture, however, approximately two-thirds remained in the collagen gel. In summary, the presence of a 3-D collagen matrix increases fibroblast fibronectin production and results in greater retention of fibronectin in the vicinity of the producing cells.

Fibroblasts in vivo reside in a three-dimensional (3-D) matrix. The 3-D culture method using collagen gels provides valuable information, but it also has some practical difficulties. In particular, the changes caused by the contraction of gels and the occasional abrupt detachment from the underlying surface have made extended culture difficult. In this study, the 3-D culture method was modified in order to observe the cells with minimal change of substrata for longer periods. The proliferation characteristics of fibroblasts cultured in gels in response to fetal calf serum (FCS), to two defined growth factors, insulin and platelet-derived growth factor (PDGF), and to a growth inhibitory factor, prostaglandin E2 (PGE2), were evaluated with this system in comparison with monolayer cultured fibroblasts. The DNA content of fibroblasts cultured both in gels and on dishes increased in response to FCS in a concentration-dependent manner. The proliferation of gel-cultured fibroblasts, however, was lower than that of dish-cultured cells, and higher concentrations of serum were necessary for proliferation. The response of gel-cultured cells to PDGF was also less than that of dish-cultured cells. In addition, fibroblasts cultured in gel culture did not respond to insulin, while the fibroblasts on dishes responded to insulin in a concentration-dependent manner. In contrast to the reduced response to growth stimulators, PGE2 inhibited proliferation in gel culture and in monolayer culture similarly. The reduced responsiveness to growth stimulation but equivalent response to growth inhibition may account for reduced proliferation of fibroblasts in 3-D culture.

Vitronectin is a multifunctional glycoprotein which is involved in several of the processes of inflammation and repair. In previous studies we demonstrated that increased concentrations of vitronectin can be detected in bronchoalveolar lavage fluids (BAL) of patients with interstitial lung disease (e.g. sarcoidosis). The outcome of sarcoidosis is generally favorable, however, some patients progress to pulmonary fibrosis. There is a need for markers indicating early fibrotic changes in the lung in patients with sarcoidosis. The present study was designed to evaluate the potential of BAL-vitronectin measurements for the assessment of disease activity in subjects with sarcoidosis. BAL-vitronectin concentrations were determined in 19 patients with biopsy proven sarcoidosis and sequential analysis of BAL-vitronectin levels were performed in 11 patients before and after therapy. Patients with active sarcoidosis had higher BAL-vitronectin concentrations (1.56 +/- 0.89 microgram/ml) than patients with inactive disease (0.68 +/- 0.33 microgram/ml; p < 0.01). Patients with active sarcoidosis received high-dose glucocorticoid treatment for four weeks followed by low-dose glucocorticoid therapy for eleven months. After high-dose medication BAL-vitronectin concentrations fell significantly (1.08 +/- 0.9 microgram/ml; p < 0.01). A further decrease in vitronectin levels resulted when therapy was continued for a year (0.75 +/- 0.48 micrograms/ml). Clinical deterioration correlated with an increase in BAL-vitronectin concentrations. Thus, measurement of BAL-vitronectin levels might be a useful marker for assessing disease activity and response to therapy in patients with sarcoidosis, but does not provide prognostic information.