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Biomedical subjects

R L Gallo

Publications and source records attributed to R L Gallo.

32 records · Page 2Linked to original sources
PubMed1994

Members of the syndecan family of heparan sulfate proteoglycans are expressed in distinct cell-, tissue-, and development-specific patterns.

The syndecans are a gene family of four transmembrane heparan sulfate proteoglycans that bind, via their HS chains, diverse components of the cellular microenvironment. To evaluate the expression of the individual syndecans, we prepared cDNA probes to compare mRNA levels in various adult mouse tissues and cultured mouse cells representing various epithelial, fibroblastic, endothelial, and neural cell types and B cells at various stages of differentiation. We also prepared antibody probes to assess whether the extracellular domains of the individual syndecans are shed into the conditioned media of cultured cells. Our results show that all cells and tissues studied, except B-stem cells, express at least one syndecan family member; most cells and tissues express multiple syndecans. However, each syndecan family member is expressed selectively in cell-, tissue-, and development-specific patterns. The extracellular domain of all syndecan family members is shed as an intact proteoglycan. Thus, most, if not all, cells acquire a distinctive repertoire of the four syndecan family members as they differentiate, resulting in selective patterns of expression that likely reflect distinct functions.

Animals↗
PubMed1993

Deficient antigen presentation by Langerhans cells from athymic (nu/nu) mice. Restoration with thymic transplantation or administration of cytokines.

Epidermal Langerhans cells (LC) are a unique subtype of I-A+ dendritic cells able to present Ag for CD4-dependent immune responses. To investigate whether cutaneous Ag presentation is regulated by thymic elements or soluble factors produced by thymus-derived cells, we compared LC function in athymic nude mice and euthymic normal controls. Examination of the ability of LC to present alloantigens to T cell-enriched responder populations, and insulin to an insulin-specific T cell hybridoma, demonstrated that this function is deficient in LC from inbred and outbred strains of congenitally athymic (nu/nu) mice compared with euthymic litter mates. Adoptive transfer of thymic tissue from euthymic to athymic mice reconstituted the ability of LC derived from athymic mice to present alloantigens. To investigate whether an altered local cytokine microenvironment was responsible for the diminished LC function in athymic mice, various cytokines were administered in vivo and in vitro before determination of alloantigen presentation by epidermal cells from athymic and euthymic mice. Continuous intraperitoneal infusion of granulocyte-macrophage colony stimulating factor (GM-CSF) or TNF-alpha, but not IL-1 alpha or IL-2, restored alloantigen presenting ability in athymic LC. In vitro preincubation of LC in GM-CSF or TNF-alpha but not in other cytokines tested also reconstituted alloantigen presentation by LC from athymic mice in most, but not all, of the experiments performed. Furthermore, analysis of cytokine production by epidermal cells in athymic and euthymic mice revealed that epidermal cells from athymic mice produce less GM-CSF and more TNF-alpha, but normal amounts of various other cytokines. However, reconstitution of athymic mice with thymic tissue did not result in normalization of GM-CSF or TNF-alpha production by epidermal cells. These data suggest that LC Ag presenting ability is regulated by thymic factors and that adequate function of cutaneous APC in situ may require the continuous presence of sufficient amounts of cytokines including GM-CSF and TNF-alpha.

Animals↗
PubMed1993

Developmental expression of the syndecans: possible function and regulation.

Recent work has made clear that heparan sulfate at the cell surface is essential for a wide variety of interactions of cells with their microenvironment, including the action of growth factors, extracellular matrix, proteases and protease inhibitors. A major source of this cell surface heparan sulfate is a multigene family of proteoglycans, the syndecans, that are expressed developmentally in association with changes in tissue organization and morphology and induced during wound repair. In this review, we describe mechanisms underlying the differential expression of the syndecans, focusing on syndecan-1. The induction of syndecan-1 can result from soluble extracellular factor(s) acting at multiple levels of cellular regulation. At the transcriptional level, the promoter of the murine syndecan-1 gene contains potential recognition sites for several well-known regulatory genes, including Hox and MyoD family members. Because changes in syndecan expression enable cells to become more or less responsive to their microenvironment, understanding these regulatory mechanisms can lead to an improved understanding of how cellular behavior is controlled during development and wound repair.

Animals↗
PubMed1992

Cyclosporin increases granulocyte/macrophage colony-stimulating factor (GM-CSF) activity and gene expression in murine keratinocytes.

Keratinocytes produce multiple cytokines in response to a variety of stimuli. The release of interleukin 1 (IL-1) from keratinocytes may be significant in initiation of cutaneous inflammation, and the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF) is thought to be important in the regulation of antigen-presenting function by epidermal Langerhans cells. Because cyclosporin inhibits interleukin 2 release from T cells, it has been suggested that cyclosporin may function as an anti-inflammatory agent within the epidermis through inhibition of keratinocyte cytokine release. This investigation examined the direct effect of cyclosporin on the production of GM-CSF by murine keratinocytes and the keratinocyte cell line PAM 212. GM-CSF bioactivity increased in cell supernatants from keratinocytes exposed in vitro to 1 microgram/ml cyclosporin for up to 24 h. GM-CSF and IL-1 mRNA levels in keratinocytes cultured under similar conditions or in the presence of lipopolysaccharide also increased. The lack of inhibition of GM-CSF expression following cyclosporin treatment is consistent with recent observations in T cells and is opposite to the effect of cyclosporin on interleukin 2.

Animals↗
PubMed1991

Tumor antigen presentation by murine epidermal cells.

The ability of epidermal Langerhans cells to present Ag for CD4-dependent immunity is well documented, and it has been hypothesized that Langerhans cells participate in the generation of immunity against incipient epidermal neoplasms by presentation of tumor-associated Ag in situ. This study examined the ability of murine epidermal cells (EC) to present tumor-associated Ag for the induction of in vivo antitumor immunity. Murine epidermal cells were deleted of Thy-1-bearing cells, cultured in 50 U/ml granulocyte-macrophage-CSF for 14 to 18 h, and pulsed with tumor fragments (TF) derived from S1509a-fibrosarcoma cells. These TF-pulsed EC were injected s.c. into syngeneic recipients at weekly intervals for a total of three immunizations and challenged with viable S1509a tumor cells 1 wk after the last immunization. Control animals received TF-pulsed allogeneic EC or EC treated identically but not pulsed with TF. EC that were pulsed with tumor cell fragments were able to induce protective immunity to tumor growth in vivo and to immunize for a significant delayed-type hypersensitivity response to injected tumor cells. The induction of antitumor immunity with TF-pulsed EC was genetically restricted, and culture of EC in granulocyte-macrophage-CSF was required for development of significant immunity. Furthermore, deletion of I-A+ cells by antibody and complement-mediated lysis eliminated the generation of immunity. Thus, I-A+ epidermal cells are capable of presenting S1509a tumor Ag for the generation of protective antitumor immunity in vivo.

Animals↗
PubMed1991

Regulation of GM-CSF and IL-3 production from the murine keratinocyte cell line PAM 212 following exposure to ultraviolet radiation.

Ultraviolet radiation (UVR) exposure induces profound changes in the synthesis and secretion of various cytokines both in vivo and in vitro. Little is known regarding the mechanism of these responses. This investigation evaluated the effects of UVR on the ability of a murine keratinocyte line (PAM 212) to produce interleukin 3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF). Subconfluent rapidly dividing PAM 212 cells were shown by RNA slot-blot hybridization studies to have increased levels of mRNA for both IL-3 and GM-CSF within 1 h of UVR exposure. However, only GM-CSF-specific bioactivity, as determined by antibody neutralization studies, was shown to increase above baseline in cell supernatants. Cells grown to confluence responded differently to UVR. Under these culture conditions an apparent decrease in bioactivity was detected after UVR exposure for both growth factors, and no change in mRNA levels was detected. In addition to culture density, removal of extracellular calcium or sodium during irradiation, treatment with amiloride, or inhibition of new mRNA synthesis with cordycepin was shown to influence the UVR-induced alteration in release of IL-3 or GM-CSF bioactivity from both confluent and subconfluent PAM 212 cells. These results demonstrate that UVR influences the release of the colony stimulating factors GM-CSF and IL-3 from keratinocyte, and suggests that the state of cell growth and conditions of membrane ion transport influence the mechanisms regulating secretion of those factors.

Animals↗
PubMed1990

A controlled trial of intralesional recombinant interferon-gamma in the treatment of keloidal scarring. Clinical and histologic findings.

Interferon-gamma (IFN-gamma) suppresses the synthesis of collagen by fibroblasts in vitro and the synthesis of collagen in vivo in animal models. Therefore, recombinant human IFN-gamma was examined for its ability to clinically modify keloids. Subjects were treated by injection of either 0.01 or 0.1 mg of recombinant human IFN-gamma into one lesional site and diluent alone into another lesional site three times per week for 3 weeks. Keloids were measured and photographed before beginning therapy and weekly thereafter. Three days after the final injection, biopsies were performed on treated and control sites. Six of eight subjects who finished the course of treatment demonstrated reduction in size at the treated site with an average reduction in height of 30.4% vs 1.1% for control sites. Lesions treated with recombinant human IFN-gamma demonstrated alterations in both the epidermis and dermis. The epidermis showed thinning of the suprapapillary plates, compact hyperkeratosis, focal or diffuse parakeratosis, exocytosis of lymphocytes, and an increased quantity of mucin. The dermis contained a diminished quantity of thickened collagen bundles and active fibroblasts and an increased number of inflammatory cells and quantity of mucin. These results suggest the feasibility of using IFN-gamma in the treatment of abnormal fibrosis. Dose-ranging studies are required to establish whether IFN-gamma can fulfill a true clinical need in the treatment of keloidal scarring.

Adolescent↗
PubMed1990

Mechanism for 193-nm laser radiation-induced effects on mammalian cells.

The cellular sites for damage in mammalian cells caused by 193-nm radiation from an argon fluoride excimer laser were investigated. The ability of Chinese hamster ovary cells to reduce a tetrazolium dye (MTT) was decreased to 37% of unirradiated control by 2.5 x 10(3) J/m2 of 193-nm radiation when measured either 4 or 24 h after irradiation. In contrast, inhibition of MTT reduction by 254-nm radiation which primarily causes DNA damage was not measurable using this assay at 4 h after exposure; at 24 h 45 J/m2 inhibited MTT reduction to 37% of control. An increase in plasma membrane permeability, detected by 51Cr release, was observed within 15 min of exposure to 193-nm radiation, whereas exposure to 254-nm radiation did not cause this immediate release of 51Cr. In control experiments, the mitochondrial poison, carbonyl cyanide m-chlorophenyl hydrazone, did not cause 51Cr release in the dark, indicating that the 193-nm radiation-induced increase in plasma membrane permeability was not subsequent to loss of mitochondrial function. [3H]-Arachidonic acid was released from C3H10T1/2 cells using low 193-nm fluences, whereas release of [3H]arachidonic acid using UVB (290-32 nm) radiation required cytotoxic fluences. DNA does not appear to be a major site of 193 nm-induced cellular damage because alkali-labile sites were not detected in cells exposed on ice to up to 2 x 10(4) J/m2 of 193-nm radiation. These results indicate that 193-nm radiation produces primary damage on the level of the plasma membrane.

Animals↗
PubMed1989

Ultraviolet radiation induces a change in cell membrane potential in vitro: a possible signal for ultraviolet radiation induced alteration in cell activity.

The regulation of a transmembrane ionic gradient, reflected by the cellular membrane potential, has been shown in several cell systems to be involved in the regulation of cell function. This investigation presents evidence that biologically relevant doses of ultraviolet radiation (UVR) will alter the membrane potential of keratinocytes in vitro. Estimation of the relative change in the steady-state membrane potential of the murine keratinocyte cell line PAM 212, the murine myelomonocytic cell line P388D1, and normal human keratinocytes in culture, were made through the use of the lipophilic cationic membrane potential sensitive probe; triphenylmethylphosphonium. Our observations indicate that UVR composed primarily of UVB (280-320 nm) radiation at doses as low as 100 J/m2 can induce a depolarization in the murine cell lines and a hyperpolarization in human keratinocytes. Evidence suggests that this difference in the direction of the membrane potential response reflects a difference in Na+/K+ ATPase activity following UVR. These results suggest a possible mechanism for modulation of keratinocyte activity induced by UVR.

Cells, Cultured↗
PubMed1989

Inhibition of allergic contact dermatitis and ultraviolet radiation-induced tissue swelling in the mouse by topical amiloride.

Amiloride is known to inhibit membrane sodium transport and has been shown in vitro to inhibit cell activation and proliferation in several model systems. These effects occur at relatively high local concentrations of amiloride. We studied the cutaneous response to the topical application of amiloride hydrochloride. Our observations demonstrated that topical application of amiloride was potent in its ability to inhibit murine tissue swelling and inflammation in response to contact sensitizing agents and ultraviolet radiation. These observations might suggest a role for amiloride or its analogues as topical anti-inflammatory or antiproliferative drugs.

Administration, Cutaneous↗
PubMed1984

Characterization of the plasma and mitochondrial membrane potentials of alveolar type II cells by the use of ionic probes.

The lipophilic cation triphenylmethylphosphonium (TPMP+) and the potassium analog Rb+, were used to monitor the membrane potential (delta psi) of freshly isolated rabbit type II alveolar epithelial cells. Type II cells were found to accumulate TPMP+ rapidly at 37 degrees C in Hanks' balanced-salt solution with 5 microM tetraphenyl boron, but this accumulation was partially due to non-membrane potential dependent binding of TPMP+ to the cell. Lysophosphatidylcholine (lysoPC) was found to abolish delta psi and permitted correction for bound TPMP+ or Rb+. TPMP+ remaining in the cell following correction for binding represents the sum of mitochondrial and plasma membrane potential dependent accumulation. The accumulation of Rb+ by the type II cell was found to be independent of the mitochondrial membrane potential and indicated a trans-plasma membrane Rb+ distribution potential of -62.9 +/- 4 mV. A similar value was obtained by estimating the plasma membrane potential dependent accumulation of TPMP+ in type II cells whose mitochondria were depolarized with carbonylcyanide m-chlorophenylhydrazone (CCCP). The release of TPMP+ due to CCCP treatment also permitted an estimation for the trans-mitochondrial membrane potential of -141.8 +/- 10 mV. These techniques of membrane potential measurements were found to be sensitive to changes in delta psi induced by a number of inhibitors and ionophores. The ability to measure the membrane potential of the type II pneumocyte, and the changes caused by various agents, should be useful in characterizing the functional responses of this pulmonary surfactant producing cell.

Animals↗
PubMed1984

Lysophosphatidylcholine cell depolarization: increased membrane permeability for use in the determination of cell membrane potentials.

Current techniques for the determination of cellular membrane potentials based on the uptake of a radiolabeled lipophilic cation, [3H]triphenylmethylphosphonium, and the cyanine dye, DiOC5(3), were analyzed in terms of the proportions of these probes which are accumulated due to potential-dependent and potential-independent forces. Measurements were made of probe uptake in two model systems: rabbit type II pneumocytes and human promyelocytic HL60 cells. For both cell types, the membrane potential-independent component of triphenylmethylphosphonium uptake was found to be a function of several variables, including the length of exposure of the cells to the transport facilitator tetraphenylboron, the concentration of tetraphenylboron, and the integrity of the cell membrane. To accurately determine the magnitude of the potential-independent component of probe uptake by type II and HL60 cells, the cell-permeabilizing agent lysophosphatidylcholine was used. The ability of lysophosphatidylcholine to depolarize cell membranes and accurately predict membrane potential-independent accumulation was found to be equal to or superior to several other techniques commonly used to achieve membrane depolarization (e.g. gramicidin, valinomycin plus high external potassium). Lysophosphatidylcholine cell treatment was found to be a simple, rapid, and accurate technique to increase cell membrane permeability and allow equilibration of intra- and extracellular ions. The method is shown to be useful for determining membrane potential-independent accumulation of both radiolabeled and fluorescent probes of membrane potential.

Animals↗