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D N Sauder

Publications and source records attributed to D N Sauder.

At least 145 records · Page 8Linked to original sources
PubMed1986

Interactions of stem cells and T lymphocytes contribute to the physiological control of cell proliferation in rapidly renewing tissues.

Control of cell proliferation, in tissues which replicate rapidly, may be exercised, at least in part, by common populations of circulating cells. Thymus-derived (T) lymphocytes possess properties which would fit them for this purpose. Among these are the functional manifestations of 'help' and 'suppression' with respect to defined physiological processes, such as immunoglobulin production; and unique traffic patterns in blood and extra-vascular tissues, including those in non-lymphoid organs such as bone marrow, skin and gut epithelium. This tropism may involve specific chemotactic agents and result in a predominance of 'suppressor' cells in target tissues. A 'steady-state' of cell proliferation could be maintained by this mechanism which is subject to humoral modulation, for instance by corticosteroids. Influx of 'helper' T lymphocytes would stimulate cell production while an excess of 'suppressors' would diminish cell renewal, as has been observed in some forms of bone marrow aplasia. Fulfillment of these roles by T cells may depend on the expression of antigens in the HLA-DR complex and it has implications for further insight into the pathogenesis of auto-immunity and neoplasia.

Animals↗
PubMed1986

Regulation of major acute-phase plasma proteins by hepatocyte-stimulating factors of human squamous carcinoma cells.

Human squamous carcinoma (COLO-16) cells release factors which specifically stimulate the synthesis of major acute-phase plasma proteins in human and rodent hepatic cells. Anion exchange, hydroxyapatite, lectin, and gel chromatography of conditioned medium of COLO-16 cells result in separation into three distinct forms of hepatocyte-stimulating factors (designated HSF-I, HSF-II, and HSF-III) with apparent molecular weights of 30,000, 50,000 and 70,000, respectively. None of the preparations contains detectable amounts of thymocyte-stimulating activity. Each of the three HSF forms stimulates the accumulation of mRNA for alpha 1-antichymotrypsin in the human hepatoma cell line, HepG2. When the same factors were added to primary cultures of adult rat hepatocytes, the expression of the same set of plasma proteins was modulated as by nonfractionated medium. The hormonally induced accumulation of mRNA for acute phase proteins is qualitatively comparable to that occurring in the liver of inflamed rats. Unlike in human cells, in rat liver cells dexamethasone acts additively and synergistically with HSFs. The only functional difference between the three HSF forms lies in the level of maximal stimulation. HSF-I represents the predominant form produced by normal human keratinocytes and closely resembles in molecular size and isoelectric point the activity produced by activated peripheral blood monocytes while the larger molecular weight forms are more prevalent in human as well as mouse squamous carcinoma cells. The observation that HSFs from different sources elicit essentially the same pleiotropic response in hepatic cells led to the hypothesis that the species-specific reaction of adult liver cells to inflammatory stimuli is pre-programmed and that the function of any HSF is to trigger and tune the execution of this fixed cellular process.

Animals↗
PubMed1986

Stimulation of muscle protein degradation by murine and human epidermal cytokines: relationship to thermal injury.

Accelerated muscle proteolysis is a characteristic of systemic reaction following trauma, sepsis, or extensive thermal injury. The factors involved in this accelerated muscle breakdown have not been fully described. However, recently leukocytic pyrogen or interleukin 1 (IL-1) have been implicated in the induction of muscle protein degradation in septicemia or trauma. The epidermal cytokine epidermal cell-derived thymocyte activating factor (ETAF) is biochemically and functionally similar to IL-1. Injury to skin can augment ETAF activity. Using a murine model, we found that thermal injury can significantly enhance ETAF/IL-1 activity in a dose-dependent fashion. In addition, ETAF can cause net muscle protein breakdown in vitro. Thus, increased amounts of ETAF produced by thermally injured skin may contribute to the accelerated muscle breakdown in extensive thermal injury.

Animals↗
PubMed1986

In vivo inflammatory activity of epidermal cell-derived thymocyte activating factor and recombinant interleukin 1 in the mouse.

Epidermal cell-derived thymocyte activating factor (ETAF), a cytokine produced by keratinocytes, has previously been shown to be biochemically and functionally very similar, if not identical, to interleukin 1 (IL-1). Both ETAF and IL-1 have been demonstrated to be chemotactic for neutrophils and mononuclear cells in vitro. In order to demonstrate that this activity has physiological relevance we have used a simple in vivo model. The present study demonstrates that injection of high-titer ETAF or purified recombinant murine IL-1 into the mouse footpad results in an influx of neutrophils into the site with peak accumulation at 4 h. Footpad swelling also occurs with a time course roughly paralleling that of the neutrophil accumulation. Injection of control proteins failed to reproduce this phenomenon. Margination of neutrophils within blood vessels was seen within 1 h of injection of ETAF or IL-1, followed by entry into the stroma by 4 h. This suggests that chemotactic activity and not merely increased adherence or inhibition of migration is occurring. 5-10 d of daily, subcutaneous injection of ETAF on the mouse flank resulted in an infiltrate of neutrophils, and to a lesser degree, mononuclear cells in association with epidermal hyperplasia, subcutaneous fibrosis, and focal muscle necrosis in the panniculus carnosus. These findings were not seen in control sites injected with media. These findings provide direct in vivo experimental evidence suggesting a physiologic role for ETAF/IL-1 in local inflammation.

Animals↗
PubMed1986

In vitro comparisons of SENCAR and BALB/c primary epidermal cells.

Grafting experiments show that the enhanced sensitivity of the SENCAR mouse to skin carcinogenesis by initiation and promotion is a property of the skin itself, suggesting the usefulness of in vitro studies to elucidate the mechanism. Such studies have indicated that cultured epidermal cells of SENCAR mice and the resistant BALB/c strain are remarkably similar in a variety of respects. DNA repair and carcinogen binding are quantitatively similar in cultured cells of SENCAR and more resistant mouse strains. Epidermal Langerhans cell (LC) number and LC-mediated functions were indistinguishable in SENCAR and BALB/c mice. Primary epidermal cells cultured in the presence of various concentrations of 12-O-tetradecanoylphorbol-13-acetate (TPA), retinoic acid, epidermal growth factor (EGF), hydrocortisone, or fluocinolone acetonide failed to reveal differences in growth between BALB/c and SENCAR cells. Cells from these animals bound comparable amounts of EGF with similar kinetics, and the modulation of this binding by TPA and retinoic acid was indistinguishable between strains. Spontaneous expression of infectious, endogenous xenotropic type C RNA virus at very low levels could be demonstrated in primary BALB/c epidermal cells and both BALB/c and SENCAR epidermal lines resistant to Ca2+-induced terminal differentiation. The number of foci of initiated cells after exposure to carcinogens in vivo or in vitro did not differ significantly between SENCAR and BALB/c, suggesting that SENCAR sensitivity is primarily to promotion. However, there are qualitative differences between SENCAR and BALB/c foci. The appearance of foci of cells resistant to terminal differentiation in untreated SENCAR cultures supports the evidence from in vivo studies for the existence of a constitutively initiated cell population in SENCAR mouse skin.

Animals↗
PubMed1986

Granulocyte colony stimulating activity derived from human keratinocytes.

Human keratinocytes are known to produce a variety of soluble mediators including epidermal cell-derived thymocyte activating factor (ETAF), which is closely related, if not identical, to interleukin (IL)-1. In the present studies, crude supernatants derived from normal keratinocytes or from the skin squamous cell carcinoma line, COLO-16, were harvested after 5 days of culture or were purified sequentially by ultrafiltration, Sephadex G-100 chromatography, and high performance liquid chromatography (HPLC), using a Synchropak AX 300 ion exchange column, followed by a TSK 4,000 size exclusion column, and their effects tested on normal human peripheral blood hemopoietic progenitors at 14 days in methylcellulose cultures. Crude and fractionated COLO-16 or normal human keratinocyte supernatants stimulated human granulocyte progenitor growth and differentiation in a dose response fashion, including both neutrophil/macrophage (GM)-type and basophil/eosinophil (Eo)-type colony-forming cells (CFU-c). The supernatants also contained an interleukin-3 (IL-3)-like activity when assayed in a proliferation assay using a subcloned, murine IL-3-dependent cell line. After two-step HPLC separation, a linear stimulatory dose-response curve for colony stimulation was obtained for GM- and Eo-type colony growth in methylcellulose. In addition, a dissociation between ETAF and both GM- or Eo-colony-stimulating activity (CSF) was found after HPLC separation. The derivation of hemopoietic CSF's from human keratinocytes gives further support to the hypothesis that these cells and their products contribute to localized inflammatory or neoplastic skin responses.

Cell Line↗
PubMed1986

Epidermal cell thymocyte-activating factor.

ETAF appears to have a multiplicity of divergent biologic effects: enhancement of thymocyte proliferation, stimulation of cells in the hypothalamus to mediate fever, stimulation of leukocyte chemotaxis, stimulation of hepatic synthesis of acute-phase proteins, induction of muscle proteolysis, augmentation of IL-2 production, and fibroblast and keratinocyte growth stimulation (Fig 4). However, it is unclear whether these divergent activities are mediated by one single cytokine, as is true for other hormones, or whether these divergent activities are mediated by several different but closely related cytokines, as is the case with interferons. In either case, ETAF, like IL 1, may play an important role in local cutaneous and systemic inflammatory and immunologic events.

Chemotaxis, Leukocyte↗
PubMed1986

Effect of age on epidermal immune function.

Like other systems in the body, the immune system deteriorates with age. Age-related changes in epidermal immune function include morphologic and functional changes in Langerhans cells, decreased production and response to epidermal thymocyte-activating factor (ETAF), and altered allergic contact dermatitis. These may be primary age-related changes in epidermal immune function or may be secondary to aging of the organism. In either case, the age-related changes in epidermal immunity may contribute to the increased susceptibility to cutaneous infections and neoplasms with advancing age.

Aged↗
PubMed1985

A simple bioassay for monocyte-derived hepatocyte stimulating factor: increased synthesis of alpha 2-macroglobulin and reduced synthesis of albumin by cultured rat hepatocytes.

Cytokines released from monocytes upon stimulation by lipopolysaccharide cause a number of cells to undergo proliferative and synthetic changes. At least one of these cytokines affects hepatocytes in vivo causing increased synthesis of a series of acute-phase proteins. We have established an in vitro micro-assay for hepatocyte stimulating factor (HSF) using primary cultures of normal rat hepatocytes. Measurement of increased synthesis of alpha 2-macroglobulin and decreased synthesis of albumin caused by exogenously added factor constitute a sensitive parameter for quantifying HSF. For comparing various cytokines preparations, we have defined a unit of HSF activity in terms of a stimulation index. We have used this assay to follow some preliminary attempts to isolate the factors responsible for stimulation of synthesis of acute-phase reactant by the liver.

Acute-Phase Proteins↗
PubMed1985

Biologic properties of epidermal cell thymocyte-activating factor (ETAF).

Recent studies have shown that in addition to Langerhans cells, keratinocytes can play an active role in immunologic events. As detected by the thymocyte co-stimulator assay, keratinocytes produce a factor with interleukin-1 (IL-1)/leukocytic pyrogen (LP)-like activity termed epidermal cell-derived thymocyte-activating factor (ETAF). ETAF like IL-1/LP can mediate fever. By gel filtration and isoelectric focusing the fever-inducing activity and the ETAF activity in the thymocyte assay co-purify. ETAF activity could be eliminated using a heterologous antibody against IL-1/LP. This antibody could also be used to immunoprecipitate ETAF. ETAF and IL-1/LP induce a peripheral neutrophilia and in vitro are chemotactic for neutrophils. Recently, ETAF has been shown to be a potent T-cell chemoattractant. ETAF-containing preparations have also been shown to stimulate hepatocytes in vitro to synthesize acute phase plasma proteins. In the case of rat hepatocytes, this can be explained by elevated levels of mRNA, although recent purifications have suggested that this hepatocyte-stimulating factor may be separable from the co-stimulator activity. ETAF has also been shown to induce muscle proteolysis in vitro. In addition to its effect on inflammatory and immune events, ETAF has growth promoting effects on keratinocytes and fibroblasts. Thus, ETAF has a multiplicity of divergent biologic effects. It remains to be determined whether the multiplicity of these effects are subserved by a single cytokine or by a family of related cytokines. In either case, ETAF may play an important role in both local cutaneous and systemic inflammatory and immune events.

Animals↗
PubMed1985

Epidermal cell-derived thymocyte activating factor (ETAF) is a potent T-cell chemoattractant.

The epidermis, in particular epidermal cytokines, have been shown to modulate a number of inflammatory and cellular immune responses. In this study we have demonstrated that the partially purified epidermal cytokine, epidermal thymocyte activating factor (ETAF), a polypeptide released by keratinocytes, is a potent T-cell chemoattractant. Compared to its ability to augment lectin-stimulated thymocyte proliferation, ETAF is much more active as a T-cell chemoattractant. The results of this study give further support to the role of local epidermal factors in immune reactivity. This finding may have particular relevance to pathologic states characterized by T-cell infiltration in the skin, such as cutaneous T-cell lymphoma.

Chromatography, Ion Exchange↗
PubMed1984

The acute-phase response of cultured rat hepatocytes. System characterization and the effect of human cytokines.

Hepatocytes were isolated from adult livers and cultured for periods of up to 5 days as monolayers at an initial density of 10(6) cells/10cm2 in Williams E medium containing insulin, dexamethasone and 5% foetal-calf serum. The daily production of 11 plasma proteins was measured by electroimmunoassay and compared with the concentrations of the same proteins in the plasma of normal rats and of those with experimental inflammation. Hepatocytes from normal rats synthesized proteins in relative amounts which were similar to the relative proportions of the same proteins in the plasma of turpentine-injected animals. The pattern changed only slowly during 5 days in culture, but it did so profoundly either when the medium was devoid of dexamethasone or when human cytokines (from endotoxin-stimulated monocytes or unstimulated human squamous-carcinoma cell line COLO-16) were added. The cytokines consistently increased the synthesis of alpha 2-macroglobulin and fibrinogen and depressed that of albumin; variable increases in the synthesis of alpha 1-acute-phase globulin, alpha 1-acid glycoprotein, haptoglobin and alpha 1-proteinase inhibitor, and variable decreases in transferrin synthesis, were seen, whereas the synthesis of antithrombin III, alpha 1-macroglobulin and prothrombin remained virtually unaffected. The cytokine effects on protein synthesis required the presence of dexamethasone. The hepatocyte-stimulating activity derived from monocytes chromatographed on Sephadex G-100 corresponding to 30 000 Da, as opposed to the lymphocyte-activating factor, which was eluted as a molecule of approx. 15 000 Da. This suggests that both activities probably reside with distinct molecular species in the preparations of human cytokines.

Acute-Phase Proteins↗
PubMed1984

Human keratinocytes and monocytes release factors which regulate the synthesis of major acute phase plasma proteins in hepatic cells from man, rat, and mouse.

Human keratinocytes and activated monocytes produces factors which can stimulate the proliferation of thymocytes. The same activity has also been implicated in regulating the expression of plasma proteins in liver cells during the acute phase reaction. To assess whether factors produced by such cells can directly influence liver cells to change the production of acute phase plasma proteins, we studied in tissue culture the response pattern of hepatic cells from three species: human hepatoma cells ( HepG2 cells), and primary cultures of rat and mouse hepatocytes. Conditioned media from the squamous carcinoma COLO-16 cells, normal epidermal cells, and activated peripheral monocytes were able to stimulate the synthesis of specific acute phase plasma proteins: alpha 1-antichymotrypsin in HepG -2 cells, alpha 1-antichymotrypsin, alpha 1-acid glycoprotein, alpha 1-acute phase protein, and alpha 2-macroglobulin in rat hepatocytes, and alpha 1-acid glycoprotein, haptoglobin, and hemopexin in mouse hepatocytes. Only in rat cells, dexamethasone was found to have further enhancing effect. The increased production of plasma proteins could be explained by an elevated level of functional mRNA. Comparing thymocyte-stimulating activities with the effects on plasma protein production, we found some difference both between the conditioned media of epidermal cells and monocytes, and between the responses of the three hepatic cell systems. Furthermore, gel chromatography of conditioned media resulted in partial separation of activities regulating liver cells and thymocytes. Since there is no strict correlation between thymocyte- and hepatocyte-stimulating activities, the presence of different sets of specific factors is assumed.

Acute-Phase Proteins↗
PubMed1984

Langerhans cell production of interleukin-1.

Epidermal Langerhans cells (LC) are related to certain cells of the monocyte-macrophage lineage and to other dendritic cells. While epidermal LC and macrophages bear receptors for the Fc portion of IgG, other dendritic cells do not. However, unlike human dendritic cells from peripheral blood, LC bear the antigen against which the OKT6 antibody is directed. Within the skin this antibody binds only to LC or indeterminate cells. Functionally LC and dendritic cells can present antigen to sensitized T cells and are capable of stimulating allogenic T cells. Since lymphokines are thought to play an important role in T-cell activation and since LC are potent stimulators of antigen-specific T-cell proliferation, we investigated whether LC could produce interleukin-1 (IL-1). Our initial studies revealed that whole epidermal cell suspensions comprised of LC, keratinocytes, and melanocytes produce a factor that is similar to macrophage-derived IL-1. We termed this factor epidermal cell-derived thymocyte-activating factor ( ETAF ). Using a panning technique we obtained a highly enriched (up to 97%) population of LC which constitutively produced significant IL-1-like activity. Using an antibody against the monocyte-derived leukocytic pyrogen (LP) which has been shown to inhibit IL-1 activity, we were able to inhibit IL-1 activity from LC-enriched cultures. The results of this study indicate that within the epidermis there are at least two cell populations, keratinocytes and LC, that can constitutively secrete potentially important soluble immunostimulatory factors.

Fluorescent Antibody Technique↗
PubMed1984

Mechanism of systemic immune suppression by UV irradiation in vivo. II. The UV effects on number and morphology of epidermal Langerhans cells and the UV-induced suppression of contact hypersensitivity have different wavelength dependencies.

We previously reported that broad band UV radiation or narrow bands of UV (Hbw 3 nm) of wavelengths 250 to 320 nm cause a systemic suppression of contact hypersensitivity (CHS) in mice, observed when the contact sensitizer is applied to a nonirradiated site. To determine if this effect is associated with UV-induced alterations in epidermal Langerhans cell (LC) numbers and morphology, we performed the following study. LC were identified by ATPase staining of EDTA-separated epidermal sheets. Electron microscope studies confirmed that this method was a satisfactory indicator of the presence of LC; we found no evidence for LC which did not stain for ATPase in either irradiated or unirradiated epidermis. Mice were irradiated on the back with narrow band UV of peak wavelength 270, 290, or 320 nm. The irradiated skin was excised 24 hr later and was stained as described. The number of LC with ATPase staining dendrites and the number of nondendritic LC were enumerated. We found that UV radiation of 270 or 290 nm caused 1) an alteration in LC morphology (loss of dendrites) and 2) a decrease in the total number of epidermal LC. Both effects occurred in a dose-dependent fashion. Previously, these same wavelengths of narrow band UV, but at higher doses, had been shown to cause systemic suppression of CHS. In this study, the doses of 270 or 290 nm UV that resulted in the decreased LC numbers and alterations in LC morphology described above were insufficient to cause systemic suppression of CHS. The converse was found if the irradiating waveband of UV had a peak at 320 nm. A dose of 320 nm UV that caused 50% systemic suppression of CHS had no effect on either the number or the morphology of LC at the site of irradiation. In addition, the number and morphology of LC were unaffected in the ventral epidermis (site of contact sensitization) of mice that had been previously irradiated on the back with a systemically suppressive dose of UV. We conclude: (a) UV-induced alterations in the number and morphology of LC at the site of irradiation are not necessary for the generation of systemic suppression of CHS by UV radiation; this indicates that the initial UV-absorbing event triggering systemic suppression is neither a loss of, nor morphologic alterations to, LC at the irradiation site. (b) A systemic effect of UV radiation on the number and morphology of LC at the unirradiated site of contact sensitization does not occur, and thus is not responsible for the UV-induced systemic suppression of CHS by UV radiation.

Adenosine Triphosphatases↗
PubMed1984

Chemotactic cytokines: the role of leukocytic pyrogen and epidermal cell thymocyte-activating factor in neutrophil chemotaxis.

Macrophage-derived leukocytic pyrogen (LP) is thought to be similar if not identical to interleukin 1 (IL 1). In addition to macrophages, keratinocytes produce a factor that has similar biologic and biochemical characteristics to IL 1, called epidermal cell thymocyte-activating factor (ETAF). Because many diseases affecting the skin are characterized by infiltration of polymorphonuclear leukocytes (PMN) and some of these disorders are associated with fever, we investigated whether ETAF like LP had pyrogenic activity, and whether ETAF or LP were chemoattractants. ETAF or LP purified by column chromatography and isoelectric focusing were found to have chemotactic activity for PMN. The fractions containing maximal chemotactic activity corresponded to maximal fever-inducing activity and maximum thymocyte-activating activity. Furthermore, the chemotactic activity of ETAF and LP could be blocked by an antibody directed against LP. The results of this study indicate that these mediators, which arise from distinct cell populations, are closely related and may play a vital role in skin as well as distant inflammatory and immunologic events.

Animals↗