Biomedical subjects

C G Larsen

Publications and source records attributed to C G Larsen.

At least 37 records · Page 2Linked to original sources

PubMed1997

Neutrophil chemotactic activity in bronchoalveolar lavage fluid of patients with AIDS-associated Pneumocystis carinii pneumonia.

Pneumocystis carinii pneumonia (PCP) is accompanied by an acute inflammatory infiltration of the lung parenchyma. The cellular infiltrate is characterized by inflammatory cells including neutrophils, lymphocytes and macrophages. Furthermore, neutrophilia in bronchoalveolar lavage (BAL) fluid has been shown to confer a poor prognosis in PCP. We therefore investigated the potential of BAL fluid from 17 patients with PCP to induce neutrophil chemotaxis. BAL fluid from patients induced considerable neutrophil chemotactic activity compared to normal controls. Elevated levels of IL-8 were detected in patient samples as compared to controls. A specific anti-IL-8 antibody significantly reduced chemotactic activity of patient samples by more than 50%. In conclusion, IL-8 appears to be a significant participant of neutrophil chemotaxis in AIDS-associated PCP, and may participate in the recruitment of neutrophils to the lung during PCP.

AIDS-Related Opportunistic Infections↗

PubMed1996

IL-8 induces T cell chemotaxis, suppresses IL-4, and up-regulates IL-8 production by CD4+ T cells.

Interleukin-8 (IL-8), a neutrophil-activating cytokine, also activates certain T cell functions such as chemotaxis. We additionally find (n = 6) that recombinant (rIL-8; 1-100 ng/ml), when added to 24 h culture of human CD4+ T cells, suppressed the spontaneous production of IL-4 (50-85%). Steady state production of Il-4 was typically around 30 pg/ml, determined by use of a solid- phase immunoabsorbant assay. De novo synthesis of IL-4 from CD4+ T cells cultured for 3 days was also evaluated by use of detection of [35S]methionine incorporation, as visualized by autoradiography of 2-D gels, and showed that IL-8 suppressed IL-4 production. This suppression of IL-4 production was confirmed in the cytosol fraction by use of Western blotting. The effect of IL-8 (100 ng/ml) was comparable to that of 10 ng/ml recombinant interferon-gamma, both strongly suppressing IL-4 production. The regulatory effect of IL-8 on IL-4 production was also indicated by the fact that addition of a neutralizing monoclonal anti-IL-8 antibody (WS.4) enhanced the spontaneous IL-4 production when added to the culture of CD4+ T cells, thereby probably inactivating the effect of IL-8 originating from the cultured T cells. Also, we observed that IL-4 mRNA expression was down-regulated when the CD4+ T cells were cultured for 12 h in the presence of 100 ng/ml IL-8. The suppression of IL-4 mRNA expression could be prevented by adding anti-IL-8 (20 microgram/ml) or IL-10 (100 ng/ml) l h before adding rIL-8. Thus, IL-8 may be an important regulator of CD4+ T cell-derived IL-4, thereby possibly regulating the balance between humoral and cellular T cell-dependent responses.

CD4-Positive T-Lymphocytes↗

PubMed1996

Localization of monocyte chemotactic and activating factor (MCAF/MCP-1) in psoriasis.

The monocyte chemotactic protein-1 (MCAF) also termed MCP-1, a strong chemotactic factor towards monocytes, is produced by several cell types present in the skin. The in situ presence of MCAF/MCP-1 protein in the skin has, however, not yet been established. Using immunohistochemical techniques we have investigated the distribution of MCAF in skin from patients with different types of psoriasis and normal healthy volunteers. We report the novel finding that psoriasis has strong positive immunostaining for MCAF located to all the layers of the epidermis, except the stratum granulosum, in pustular, guttate and chronic plaque psoriasis. In the dermis, infiltrating cells in the perivascular aggregates and the blood vessels stained positive for MCAF. No significant differences were observed between the different subtypes of psoriasis except that strongly positive infiltrating cells were observed in the epidermal pustules in pustular psoriasis. In normals positive staining was observed in all the layers of the epidermis and in a few perivascular cells and blood vessels in the dermis. Where present in normal and diseased skin, eccrine ducts of sweat glands and sebaceous glands stained positive for MCAF. Arrector pili muscles were in all cases negative. These findings are consistent with a role for MCAF in attracting inflammatory cells, including monocytes, into the skin in psoriasis.

Chemokine CCL2↗

PubMed1996

Psoriasin: a novel chemotactic protein.

Inflammatory skin disorders such as psoriasis show a preferential epidermal infiltration of neutrophils and T lymphocytes. This observation raises a question as to which factors determine the appearance and composition of leukocyte tissue infiltrations. Previously, we described a low molecular mass calcium-binding protein (psoriasin, molecular mass 11,457 Da, pI 6.77) belonging to the S1OO family that is highly upregulated in psoriatic keratinocytes and whose expression patterns implied a role in the inflammatory response. Here we report that human psoriasin is a potent and selective chemotactic inflammatory protein for CD4+ T lymphocytes and neutrophils at concentrations of about 10(-11) M. Psoriasin is not structurally related to the alpha or the beta chemokine subfamilies or to lymphotactin, a member of a newly described class of chemokines. Thus, we have observed a chemotactic protein outside the chemokine subfamilies that could be an important new inflammatory mediator.

CD4-Positive T-Lymphocytes↗

PubMed1995

Recombinant human growth-regulated oncogene-alpha induces T lymphocyte chemotaxis. A process regulated via IL-8 receptors by IFN-gamma, TNF-alpha, IL-4, IL-10, and IL-13.

The human cytokine growth-regulated oncogene (GRO)-alpha is a small glycoprotein secreted by monocytes, endothelial cells, glycoprotein secreted by monocytes, endothelial cells, fibroblasts, synovial cells, and some tumor cells such as melanoma cells. It is structurally related to IL-8 and can activate neutrophils, whereas it induces chemotaxis, exocytosis, and a respiratory burst in neutrophils. To date, its functions on T lymphocytes have not been well established. We report here that recombinant human (rh)GRO-alpha is a potent chemoattractant for freshly isolated T lymphocytes, but not for anti-CD3 mAb-activated T lymphocytes. It attracts CD4+ and CD8+ T lymphocyte subsets to an equal extent. The migrating T lymphocytes toward rhGRO-alpha are predominantly CD45RO+ memory CD4+ and CD8+ subsets. The chemotactic migration of T lymphocytes toward rhGRO-alpha is stimulated via the IL-8 receptors on the cells. This process can be augmented by IFN-gamma and TNF-alpha, and inhibited by IL-4, IL-10, and IL-13. In addition, we also document that on T lymphocytes there exist IL-8 receptors that can be up-regulated by IFN-gamma, TNF-alpha, and IL-2. Our results demonstrate that rhGRO-alpha gene encodes for an inflammatory mediator that stimulates the directional migration of T lymphocytes. It may thus be another important mediator in the diseases in which T lymphocytes form the major constituent of the cellular infiltration.

Antigens, CD↗

PubMed1995

The delayed-type hypersensitivity reaction is dependent on IL-8. Inhibition of a tuberculin skin reaction by an anti-IL-8 monoclonal antibody.

Cell-mediated immune reactions are essential to our immune response toward foreign organisms such as microorganisms, or in the response toward foreign tissue Ags, as seen in the rejection of allogeneic transplanted organs. Similar reactions form the basis for the development and the progression of delayed-type hypersensitivity (DTH) reactions. We found that the alpha-chemokine IL-8 plays an important pathophysiologic role for the development of a DTH reaction because infusion of a neutralizing anti-IL-8 mAb (WS-4) was able to suppress the development of a tuberculin skin reaction in rabbits, as judged by histologic, biochemical, and clinical examinations. Thus, the number of neutrophil granulocytes and lymphocytes at the site of tuberculin injection was decreased considerably, and the clinical signs of inflammation were suppressed almost completely at 24 h after intracutaneous injection of tuberculin, as judged by the size of the infiltrates. In contrast, we did not see any effect on the visible erythema of the skin. We found that the tissue content of myeloperoxidase (MPO), reflecting the number of infiltrating neutrophils, was lowered significantly. Furthermore, immunohistochemical analysis confirmed that IL-8 immunoreactivity is actually enhanced in the skin of positive tuberculin reactions. The results indicate that IL-8 plays an important role for the early accumulation of leukocytes in the skin and for the clinical signs of a DTH reaction.

Animals↗

PubMed1995

Interleukin-8 induces its own production in CD4+ T lymphocytes: a process regulated by interleukin 10.

The neutrophil and T cell chemotactic factor interleukin 8 (IL-8) is believed to play a pathophysiological role in the development of various inflammatory disorders. So far no other effects of IL-8 on T cells have been observed. We observed that purified CD4+ T cells in particular, but also CD8+ T cells, spontaneously synthesize IL-8 mRNA and secrete IL-8 protein. The culture supernatants of CD4+ T cells contained T cell chemotactic activity as well as IL-8 protein. In addition, we confirmed the ability of CD4+ T cells to produce IL-8 by double immunofluorescence staining and by the demonstration of IL-8 mRNA expression. Further, IL-8 induced its own production in CD4+ T cells, while its synthesis by CD8+ T cells was low and not always auto-stimulatory. Both the spontaneous, as well as the IL-8 induced IL-8 production, could be inhibited in the presence of human interleukin 10 (100 ng/ml). This observation suggests that IL-10 plays a homeostatic role in regulating the IL-8 circuit in CD4+ T cells.

Autoradiography↗

PubMed1995

Regulation of human T lymphocyte chemotaxis in vitro by T cell-derived cytokines IL-2, IFN-gamma, IL-4, IL-10, and IL-13.

There has been a number of conflicting reports regarding the T lymphocyte chemotactic activities of several cytokines. IL-2 and IFN-gamma are known to promote augmentation of immune inflammation, whereas IL-4, IL-10, and IL-13 display immunomodulatory effects on inflammatory cells including inhibition of cytokine production. Their effects on chemotaxis of inflammatory cells are unknown. We observed that IL-1 alpha could induce chemotaxis both in overnight cultured and anti-CD3 mAb-activated T lymphocytes and that overnight culture and anti-CD3 activation increase the number of IL-1R on T lymphocytes. In contrast, IL-8 selectively attracts freshly isolated T lymphocytes. Staurosporine inhibits freshly isolated T lymphocyte chemotaxis toward IL-8, whereas tyrphostin 23 inhibits chemotaxis of overnight cultured and anti-CD3-activated T lymphocytes toward IL-1 alpha. We have found that IL-2 and IL-13 inhibit the chemotactic migration of both CD4+ and CD8+ T lymphocytes toward IL-8, and RANTES. IL-4 inhibits only CD8+ T lymphocyte chemotaxis toward RANTES, IL-8 and IL-10. IL-10 inhibits only CD4+ T lymphocytes in their chemotactic response toward RANTES and IL-8. IFN-gamma does on the other hand augment the sensitivity of human T lymphocytes to chemotactic stimuli. Thus, our results demonstrate that different proinflammatory cytokines will induce chemotactic migration of T lymphocytes under different circumstances acting through different signaling pathways. The T cell-derived cytokines IL-2, IL-4, IL-10, and IL-13 are able to block further T lymphocyte chemotaxis, thus leading to a focusing of T lymphocytes in an area of T lymphocyte activation. These mechanisms seem relevant in our understanding of the specific and continuous localization of T lymphocytes in allergic and autoimmune disorders.

Chemokine CCL5↗

PubMed1993

Human IL-10 is a chemoattractant for CD8+ T lymphocytes and an inhibitor of IL-8-induced CD4+ T lymphocyte migration.

Human IL-10 (hIL-10) is a newly described cytokine that was originally identified as a cytokine synthesis inhibitory factor regulating the production of several pro-inflammatory cytokines such as IL-1 alpha, IL-1 beta, IL-6, IL-8, TNF-alpha, and IFN-gamma. Additionally, hIL-10 also inhibits the macrophage-dependent proliferative response of CD4+ T lymphocytes to Ag stimulation, and it down-regulates the constitutive class II MHC expression on human monocytes. We report hIL-10 to be a potent and specific chemotaxin for human T lymphocytes with optimum activity in the range between 10 and 100 U/ml. Checkerboard analysis shows the activity to be chemotactic and not chemokinetic. The chemotactic activity is directed toward CD8+ T lymphocytes and not towards CD(4+)-enriched cells. Also, hIL-10 lacks chemotactic activity toward human monocytes or neutrophil granulocytes. Further, we found that hIL-10 inhibits the chemotactic response of CD4+, but not CD8+, T cells toward IL-8. Because hIL-10 can be produced by several cells including CD4+ T cells of the Th2 type, our results suggest that hIL-10 participates in a complex regulatory circuit between CD4+ and CD8+ T cells with implications for the control of lymphocyte-mediated inflammatory responses.

CD4-Positive T-Lymphocytes↗

PubMed1993

Expression of monocyte chemotactic and activating factor (MCAF) in skin related cells. A comparative study.

A significant proportion of the infiltrating cells in several inflammatory skin diseases, including psoriasis and allergic contact dermatitis, are monocytes. Additionally, it is known that the cytokine monocyte chemotactic and activating factor (MCAF) can be produced by several cell types present in the skin, suggesting a significant role for MCAF in the accumulation of monocytes during immunological and inflammatory skin reactions. We have recently developed a precise method for quantification of the amount of a specific mRNA species in a given sample and have used this technique to compare specific MCAF mRNA amounts in cultures of human keratinocytes, dermal fibroblasts, endothelial cells, and monocytes, after stimulation with interleukin 1 alpha (IL-1 alpha) for 6 h. Endothelial cells produced very high, monocytes and fibroblasts intermediate, and keratinocytes low amounts of MCAF mRNA. We have also performed time course studies of MCAF mRNA levels in the four cell types. Our findings suggest that the regulation of MCAF mRNA expression in these cells parallels the regulation of the lymphocyte and neutrophil chemotactic factor interleukin 8.

Cells, Cultured↗

PubMed1993

ETH615, a synthetic inhibitor of leukotriene biosynthesis and function, also inhibits the production of and biological responses towards interleukin-8.

ETH615 (4-(2-quinolylmethoxy)-N-(3-fluorobenzyl-phenyl-amino-methyl -4- benzoic-acid), a synthetic inhibitor of leukotriene B4 production and activities, was tested for its effect on the production of and biological responses towards human interleukin-8. We found that ETH615 inhibits lipopolysaccharide-induced (LPS-induced) expression of interleukin-8 messenger-RNA (mRNA) and interleukin-8 production in human peripheral blood mononuclear cells. We also observed that ETH615 completely inhibited interleukin-8 as well as leukotriene B4 directed chemotaxis of human neutrophils in a dose-dependent manner. A moderate effect on fMLP-directed neutrophil chemotaxis was observed. Further, no significant effect on either interleukin-8, leukotriene B4 or fMLP-directed T-cell migration was observed. These results further support the concept of a cytokine-leukotriene regulatory circuit and encourage the establishment of clinical trials testing the effect of ETH615 on inflammatory skin diseases, which are characterized by high levels of interleukin-8 and leukotriene B4 in lesional skin.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1992

Interleukin-8 stimulates the formation of 15-hydroxy-eicosatetraenoic acid by human neutrophils in vitro.

Interleukin-8 (IL-8), is a potent activator of polymorphonuclear leukocyte (PMN) functions including chemotaxis, superoxide anion production, and enzyme release and it is also chemotactic for lymphocytes. Additionally, it has recently been shown that IL-8 stimulates the formation of 5-lipoxygenase (LO) products of arachidonic acid (AA) by human PMNs. The purpose of the present study was to determine whether IL-8 also might affect the formation of 15-LO products from AA. Purified PMNs in phosphate buffered saline were preincubated with and without exogenous AA (10(-5)-10(-4) M) for 10 min. Then IL-8 was added in biologically relevant concentrations ranging from 0.1 to 100 ng/ml and incubation was carried out for 5 min at 37 degrees C. Lipids were then extracted from supernatants, and eicosanoids were determined by quantitative RP-HPLC. Compared with unstimulated cells, IL-8 resulted in a dose dependent increase in both LTB4 and 15-HETE (up to 125% and 40% at 100 ng/ml, respectively). This increase in eicosanoid formation required the presence of exogenous AA. These results indicate that IL-8 is both a potent stimulator of 5-LO activity and of 15-LO activity. LTB4 can induce both inflammation and contribute to hyperproliferation in the skin. 15-HETE in contrast has the ability to inhibit the effects induced by LTB4. Because IL-8 is able to stimulate both LTB4 and 15-HETE formation, the effect of IL-8 as a putative regulator of inflammatory processes may be dependent on the relative stimulation of 5-LO and 15-LO.

Chromatography, High Pressure Liquid↗

PubMed1992

The effect of second-line antirheumatic drugs on interleukin-8 mRNA synthesis and protein secretion in human endothelial cells.

Interactions between interleukin 8 (IL-8) and endothelial cells play an important role in the emigration of mononuclear cells from the blood into areas of inflammation. We examined the ability of specific second-line antirheumatic drugs to regulate (IL-8) gene expression and protein secretion in interleukin 1 (IL-1) stimulated human umbilical vein endothelial cells and peripheral blood mononuclear cells. The drugs sodium aurothiomalate, D-penicillamine and sulphasalazine were all able to modulate IL-8 mRNA synthesis in and protein secretion from endothelial cells. A bimodal effect was observed: at low concentrations IL-8 was suppressed, whereas higher concentrations resulted in an increased IL-8 production. In endothelial cells, treatment with hydrocortisone led to a linear suppression of IL-8 production in concentrations ranging from 0.5 micrograms/ml up to 500 micrograms/ml. Sulphapyridine, auranofin, hydroxychloroquine and methotrexate, had no effect on IL-8 secretion in endothelial cells. By contrast, 5-aminosalicylic acid induced a threefold increase in the IL-8 release. In peripheral blood mononuclear cells it was only possible to suppress the IL-8 production by hydrocortisone treatment. These results indicate that suppression of IL-8 production in endothelial cells could be an important factor in the mode of action for a number of second-line antirheumatic drugs.

Anti-Inflammatory Agents↗

PubMed1991

1,25(OH)2-D3 is a potent regulator of interleukin-1 induced interleukin-8 expression and production.

Interleukin 8 (IL-8) is a potent leukocyte chemotactic and activating cytokine produced by keratinocytes, fibroblasts, peripheral blood monocytes (PBMC) and endothelial cells. IL-8 is believed to play an important role in the development of inflammation and is thus an obvious target for therapeutical modulation. We studied the possible effect of an endogenous immune modulator 1,25(OH)2-cholecalciferol (1,25(OH)2-D3) on the IL-1-induced IL-8-production by several types of cells. 1,25(OH)2-D3 inhibited the IL-1-alpha induced IL-8 production and mRNA expression in keratinocytes, fibroblasts and PBMC, but not in endothelial cells. Optimal vitamin concentrations varied between 10(-10) and 10(-11) M. These results suggest a potential role of this hormone in the regulation of chemotactic cytokine production.

Calcitriol↗

PubMed1991

Recombinant human interleukin-8 is a potent activator of canine neutrophil aggregation, migration, and leukotriene B4 biosynthesis.

Interleukin-8 (IL-8), formerly known as NAP-1, is formed by a variety of cells upon stimulation with IL-1 or tumor necrosis factor (TNF). The biologic activity of the cytokine involves activation of almost every neutrophil function studied so far in different species. In the present study, we compared the effects of recombinant human IL-8 (rIL-8) and the lipid mediators, leukotriene B4 (LTB4) and platelet-activating factor (PAF), on neutrophil functions in dogs. All three chemotactic factors induced neutrophil aggregation and chemotaxis, with rIL-8 being far more potent than LTB4 and PAF. The migration induced by rIL-8 was significantly greater than that observed towards LTB4 and PAF. In the aggregation assay, rIL-8 was shown for the first time to be a potent stimulant. The aggregation response was more persistent than that obtained with LTB4 and PAF and the potency of rIL-8 was greater. An intradermal dose-response study showed that rIL-8 is an extremely potent inducer of selective neutrophil infiltration in canine skin. The infiltration was more pronounced than following injection of LTB4 or PAF. It was proposed that the superior effect of rIL-8 was caused by a synergistic effect between injected rIL-8 and LTB4, which was shown to be produced in biologically active amounts by canine neutrophils stimulated with rIL-8. From a therapeutic point of view, the simultaneous presence of rIL-8 and LTB4 in inflammatory skin diseases highlights the need to develop drugs that inhibit the production and/or effect of both mediators.

Animals↗

PubMed1991

Quantitative determination of IL-1 alpha-induced IL-8 mRNA levels in cultured human keratinocytes, dermal fibroblasts, endothelial cells, and monocytes.

The presence of the leukocyte chemotactic cytokine interleukin 8 (IL-8) in psoriatic scales and in epidermal tissue overlying allergic patch test reactions suggests a role for this cytokine in certain inflammatory skin diseases. IL-8 can be produced by several cell types present in the skin. Their relative potentials for IL-8 expression has, however, not yet been studied, due to the lack of convenient methods for quantitative comparison of specific mRNA amounts in different cell types. Using a new method for quantification, we compared specific IL-8 mRNA amounts in cultures of keratinocytes, dermal fibroblasts, endothelial cells, and monocytes, stimulated with interleukin 1 alpha (IL-1 alpha). Endothelial cells produced very high, fibroblasts and monocytes intermediate, and keratinocytes low amounts of IL-8 mRNA. We also studied the time course of IL-8 mRNA levels in the four cell types following IL-1 alpha stimulation, and found a clear difference both in onset and stability of the response. We discuss the different strength of the response at different time points in the cell types analyzed in relation to their possible role in regulation of the normal response to stimulation.

Cells, Cultured↗

PubMed1991

Increased tryptase levels in suction-blister fluid from patients with urticaria.

The levels of tryptase in the suction-blister fluid from patients with chronic urticaria, urticaria pigmentosa, cholinergic urticaria, urticarial dermographism, prurigo of unknown origin, eczema, psoriasis, atopic dermatitis, and from healthy controls were studied. The blister fluid from controls contained up to 15 micrograms/l of tryptase, whereas that from patients with active urticaria contained greater than 50 micrograms/l. This study demonstrates that patients with urticaria have mast cells that readily release tryptase in both the lesional and non-lesional areas of skin.

Adult↗

PubMed1991

RNA purification from epidermal suction blisters.

Certain inflammatory skin diseases are accompanied by increased cytokine concentrations in the epidermis. To determine whether these cytokines are synthesized in the epidermis or exported from underlying tissues, epidermal RNA was analysed for the presence of their messenger RNAs. We report a method for RNA extraction from pure epidermal samples isolated by the suction blister method. The yield of total RNA was sufficient for hybridization experiments (12-38 micrograms per seven blisters, 5 mm in diameter). Using RNA extracted by this method, we have demonstrated the presence of messenger RNA for glyceraldehyde-3-phosphate-dehydrogenase in 13 preparations from suction blisters obtained from tuberculin skin reactions, positive patch test reactions, or normal skin. We did not, however, observe messenger RNA for interleukin 1 alpha or 8 in these preparations.

Blister↗