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Biomedical subjects

D N Sauder

Publications and source records attributed to D N Sauder.

At least 55 records · Page 3Linked to original sources
PubMed1997

Modulation of TGF-beta 1 production from human keratinocytes by UVB.

Transforming growth factor-beta (TGF-beta) plays an important role not only in cell growth control but also in inflammation and immunoregulation. There are at least five different isoforms of TGF-beta. TGF-beta 1 has a large variety of biological functions including the modulation of inflammation and the immune system and has most extensively been studied in skin. Since ultraviolet B (UVB) is known to induce skin erythema and immunosuppression, we sought to examine whether UVB would alter the expression and production of TGF-beta 1 in normal human keratinocytes. Using reverse transcription-polymerase chain reaction (RT-PCR), constitutive expression of TGF-beta 1 mRNA was detected in keratinocytes and the level of TGF-beta 1 mRNA was increased 4 and 8 h after 300 J/m2 UVB irradiation. Production of TGF-beta 1 protein in culture supernatants assayed by ELISA was also increased at 24 h after irradiation. Cycloheximide treatment blocked this TGF-beta 1 protein induction indicating de novo protein synthesis of TGF-beta 1 from keratinocytes induced by UVB. These results suggest a possible role for TGF-beta 1 in UVB-induced skin inflammation and immunosuppression.

Cells, Cultured↗
PubMed1996

Contribution of the CD28 molecule to allergic and irritant-induced skin reactions in CD28 -/- mice.

The CD28 molecule is thought to be essential for the costimulatory signals and is required for mitogenic activation of T cells. The aim of this study was to evaluate the contribution of CD28 in contact hypersensitivity using CD28 gene-targeted (CD28 -/-) mutant mice. Contact hypersensitivity to dinitrofluorobenzene and oxazolone was significantly decreased in CD28 -/- mice compared with that in normal (C57BL/6) mice. Significant increases in IL-2 mRNA were detected in the skin after dinitrofluorobenzene challenge in normal mice, while this response was blunted in CD28 -/- mice. In addition, responses to irritant chemicals (croton oil and phenol) were also impaired in CD28 -/- mice. IL-2, IFN-gamma, and TNF-alpha mRNA levels were lower in CD28 -/- mouse skin treated with phenol. T cells from CD28 -/- mice did not bind to epidermal cells derived from normal mice, while cocultivation of T cells with epidermal cells from normal mice demonstrated a significant binding. These results indicate that the CD28 molecule is required not only for optimal induction of allergic contact dermatitis, but also for the development of irritant-induced skin inflammation. The expression of B7-1 and B7-2 molecules on epidermal cells was induced by an allergen treatment in normal and CD28 -/- mice, whereas only B7-2 was induced after irritant treatment. Lack of CD28 signaling may influence cutaneous inflammation by modulating skin cytokine profiles, possibly due to the decreased contact of T cells with other cell populations expressing ligands for CD28. In addition, the results of this study suggest that allergic contact dermatitis and irritant dermatitis have overlapping pathophysiologic mechanisms, but subtle differences exist.

Animals↗
PubMed1996

Ultrasound backscatter microscope analysis of mouse melanoma progression.

The incidence and mortality rate of cutaneous melanoma continue to increase throughout the world, making the study of melanoma biology an important area of current research. While recent breakthroughs in transgenic mouse technology have led to promising mouse skin models of melanoma, there is presently no technique available for quantitatively studying subsurface melanoma progression, in vivo. We demonstrate the first application of an imaging method called ultrasound backscatter microscopy (UBM) for imaging early murine melanomas with spatial resolution of 30 microns axial and 60 microns lateral. Murine B16 F10 melanomas have been imaged from their earliest detection, over several days, until they are 2 to 5 mm in diameter. Melanoma dimensions measured by UBM were found to be in excellent agreement with those determined histopathologically on the excised tumours. The relative rms errors in UBM-determined melanoma height and width were found to be 8.7% and 4.2%, respectively. The mean rate of increase in tumour height of early murine melanoma was found to be 0.37 +/- 0.06 mm/day. Computer-generated volumetric renderings of melanomas have been produced from three-dimensional image data, allowing quantitative comparisons of tumour volumes to be made. Using a priori assumptions of ellipsoid tumour shape, the relative error in UBM-determined volume was shown to be less than 17%. These results should be of considerable interest to investigators studying melanoma biology using mouse skin models, and have implications in the use of high frequency ultrasound imaging for the clinical assessment of cutaneous melanoma.

Animals↗
PubMed1996

The role of CD4 molecules in the induction phase of contact hypersensitivity cytokine profiles in the skin and lymph nodes.

We have previously demonstrated that CD4 gene-targeted mutant mice (CD4- mice) demonstrate hyporesposiveness in contact hypersensitivity (CHS) suggesting that CD4 molecules are required for optimal induction of CHS. In the present study, we wished to examine the mechanisms of this hyporesponsiveness, in particular, we examined whether cytokines were altered in the skin and lymph nodes of CD4- mice following exposure to the contact allergen dinitrofluorobenzene (DNFB). Cytokine mRNA in the ear skin and draining lymph nodes (DLN) were examined by reverse transcription-polymerase chain reaction (RT-PCR) at various times after sensitization. Skin cytokine patterns revealed that in normal mice, interleukin (IL)-2, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha mRNA levels increased at 12 hr sensitization, whereas these cytokines were below the level of detection in CD4- mice. In the DLN of normal mice following the hapten application, sequential upregulation of cytokine mRNA including IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-10, IFN-gamma and TNF-alpha was found. No change was seen for IL-1 alpha, IL-1 beta, IL-10 and TNF-alpha and IL-2, IL-4 and IFN-gamma mRNA levels were below the level of detection in DLN from CD4- mice following the hapten application. However, IL-1 beta, IL-2 and TNF-alpha mRNA levels of lymph node cells from CD4- mice could be upregulated by phorbol myristate acetate in vitro. Flow cytometry study has revealed that the number of Langerhans' cells (LC) in DLN of CD4- mice was similar to that of normal mice, thus, inferring that the alterations of cytokine milieu in the ear skin did not have a significant effect on LC migration to DLN. These results suggest that CD4 molecules are crucial for the induction of certain cytokines in the skin and in inducing sequential cytokine signals in DLN required for optimal development of CHS, but that these changes in cytokines do not effect LC migration.

Animals↗
PubMed1996

Effect of a novel topical immunomodulator, S-28463, on keratinocyte cytokine gene expression and production.

A new immunomodulating agent, imiquimod, has been reported to have antiviral and antitumor activities in animal models. S-28463 (4-amino-2-ethoxymethyl-alpha, alpha-dimethyl-1H-imidazo[4, 5-c]quinoline-1-ethanol), an analog of imiquimod, has more potent antiviral activity in animals than imiquimod. It has also been shown to be more potent at inducing cytokines in human blood in vitro. However, its precise role as an immunomodulator in the skin has not been determined. We investigated the effect of S-28463 on human keratinocyte (KC) production of interferon-alpha (IFN-alpha) and other proinflammatory cytokines, including interleukin (IL)-1alpha, IL-8, and tumor necrosis factor-alpha (TNF-alpha). Human KC were incubated with S-28463 at two concentrations (1 microgram/ml and 10 micrograms/ml) for 6 h. Cytokine gene expression was analyzed by reverse-transcriptase PCR. In human KC, S-28463 stimulated significant increases in IFN-alpha mRNA at both concentrations. IL-1alpha mRNA increased 1.4-fold at 10 micrograms/ml. IL-8 mRNA was upregulated 2.5-fold at 10 micrograms/ml. Twenty-four hours after treatment, IL-1 alpha, IL-8, and TNF-alpha protein were increased, but IFN-alpha was below the level of detection. These results suggest that in the skin, S-28463-induced-IL-1 alpha, IL-8, and TNF-alpha production may be involved in the immunomodulating action of S-28463.

Adjuvants, Immunologic↗
PubMed1996

Hyporesponsiveness in contact hypersensitivity and irritant contact dermatitis in CD4 gene targeted mouse.

To determine the role of CD4 molecules in the generation and regulation of contact hypersensitivity (CHS), we treated mice lacking the CD4 gene as a result of targeted disruption with dinitrofluorobenzene to induce CHS. The mutant mice lacking CD4 (CD4(-) mice) showed marked hyporesponsiveness in CHS compared with normal syngeneic C57BL/6 mice (38.3 +/-9.0% of normal at 24 h after the challenge assessed by net ear swelling; p < 0.025). CD4(-) mice had a larger CD4-8- double negative T-cell receptor alpha beta+ cell population in the lymph nodes than did normal mice, and the increase of this cell population was observed in CD4(-) mice after sensitization. Draining lymph node cells from sensitized normal mice restored the responsiveness in CD4(-) mice, but those from sensitized CD4(-) mice were less effective in restoring the CHS response in normal mice. Langerhans cell numbers were normal, and function, as assessed by the ability to present soluble hapten, was not impaired in CD4(-) mice. Skin cytokine profiles demonstrated an increase in interferon-gamma, interleukin-2, and interleukin-4 mRNA levels after challenge in normal mice, whereas this response was blunted in CD4(-) mice. CD4(-) mice also showed hyporesponsiveness in inflammatory reaction to irritant chemicals. These results suggest that the CD4 molecule is required for optimal induction of CHS as well as irritant contact dermatitis and may influence the development of CHS by modulating the cytokine profiles in the skin.

Animals↗
PubMed1996

Tumour necrosis factor receptor II (p75) signalling is required for the migration of Langerhans' cells.

Langerhans' cells (LC) represent the major antigen-presenting cells within the epidermis. Following exposure of the skin to antigen, LC take up antigen, migrate into draining lymph nodes (DLN) and present processed antigen to T lymphocytes, thereby initiating an immune response. The molecular mechanisms responsible for LC migration remain unclear. Cytokines, in particular tumour necrosis factor-alpha (TNF-alpha) have been suggested to influence LC migration. There are two distinct membrane receptors for TNF-alpha, TNF receptor I (TNF-R1, p55) and TNF receptor II (TNF-R2, p75), thought to be responsible for distinct TNF-alpha activities. It is believed that most of TNF biological activities are mediated via TNF-R1. In order to examine the role of TNF-R1 signalling in LC migration, we utilized TNF-R1 gene-targeted mutant mice. Following application of the hapten fluorescein isothiocyanate (FITC), FITC-bearing cells in DLN were examined by flow cytometry. A normal number of FITC+/Ia+ cells (LC) were found in DLN from TNF-R1-deficiency mice, suggesting that TNF-R1-dependent signalling is not crucial for LC migration. To investigate the possibility of signalling through TNF-R2, blocking studies using a neutralizing anti-TNF-alpha antibody were performed. The results revealed that anti-TNF-alpha antibody significantly inhibited LC accumulation in DLN in TNF-R1-deficient mice, thus suggesting that TNF-R2 signalling is involved in LC migration from skin to DLN and that murine LC express TNF-R2.

Animals↗
PubMed1996

High frequency 40-MHz ultrasound. A possible noninvasive method for the assessment of the boundary of basal cell carcinomas.

BACKGROUND: Ultrasound imaging systems operating close to 20 MHz in frequency have been used to image skin tumors. Ultrasound imaging at 20 MHz has been used to determine the boundaries of basal cell carcinomas (BCCs). An inherent shortcoming of imaging systems operating at these frequencies is their limited resolution. OBJECTIVE: We investigated whether 40-MHz ultrasound imaging could provide higher resolution compared with the lower frequency systems and thus be a superior, noninvasive method of assessing the boundaries of BCCs. METHODS: Nine BCCs from six individuals were examined clinically and ultrasonographically, and then biopsied to confirm diagnosis. The depth of BCCs measured on histological sections was compared with the corresponding value obtained using ultrasound. For this study we required a nonsurgical, nondestructive means of treating BCCs that would allow repeated ultrasound imaging, and therefore topical 5-flurouracil (5-FU) was chosen. Following 5-FU therapy a biopsy was obtained from the site of the treated BCC after ultrasound imaging had been performed. Clinical, ultrasonic and histopathologic evaluation of each BCC was carried out independently by different individuals. At the end of the study all the BCC sites were treated surgically be electrodesiccation and curettage or completely excised. RESULTS: High resolution ultrasound images of BCCs were obtained with agreement between histology and ultrasound findings in all none lesions prior to therapy and in eight of none lesions posttherapy. There was a significant correlation between the depth of BCCs measured histologically and using ultrasound (P = 0.0004, r = 0.92). CONCLUSIONS: This study suggests that 40-MHz ultrasound may provide an estimate of the boundary of a BCC in vivo. High frequency 40-MHz ultrasound imaging may be an adjunct to clinical and histologic evaluation but does not replace the need to obtain tissue for microscopic examination.

Aged↗
PubMed1996

Effects of UVB irradiation on keratinocyte growth factor (KGF) and receptor (KGFR) expression in cultured human keratinocytes.

Keratinocyte growth factor (KGF) and its receptor (KGFR) are thought to play important roles in normal keratinocyte growth and differentiation. Since UVB radiation is known to influence keratinocyte growth, we sought to determine whether UVB would alter the expression of KGF and KGFR. Using a reverse-transcription coupled polymerase chain reaction (RT-PCR), the present study examined the expression of KGF and KGFR mRNA in cultured normal human keratinocytes exposed to UVB irradiation. Total cellular RNA was extracted from cultured keratinocytes at various time points after irradiation, reverse transcribed and used for PCR amplification using primers specific for KGF and KGFR. Constitutive expression of KGFR mRNA, but not KGF mRNA, was detected in normal cultured human keratinocytes. After UVB irradiation at 300 J/m2, the KGF mRNA remained undetectable while the KGFR mRNA level was significantly decreased. The down-regulation of KGFR mRNA expression was also confirmed by Northern blot analysis. Immunohistochemical studies demonstrated a decreased positive signal of KGFR in human keratinocytes after UVB irradiation. Our results suggest a possible role for the KGF-KGFR signalling pathway in the skin after exposure to UVB, and that UVB-induced growth inhibition of keratinocytes in hyperproliferative skin disorders may be related to downregulation of KGFR.

Cells, Cultured↗
PubMed1996

Keratinocytes and cytokine/growth factors.

Cytokines are polypeptide growth factors produced by most nucleated cells in the body, including epithelial cells, keratinocytes, and Langerhans cells in the skin. Cytokines can be classified into interleukins, tumor necrosis factors, chemokines, colony-stimulating factor, interferons, and growth factors. Like classic hormones, cytokines bind to specific receptors to transmit their messages to target cells. Cytokine receptors can be divided into three cytokine receptor superfamilies: the immunoglobulin superfamily, the hematopoietin family, and the tumor necrosis factor family. Following cytokine/cytokine-receptor binding (first messenger), a signal transduction pathway is initiated. Factors affecting homeostasis in the skin and oral mucosa include a delicate balance between cytokines/cytokine-receptors and their antagonists. An imbalance in these variables can influence the development of cutaneous and oral diseases-such as lichen planus, autoimmune disorders, and some neoplastic processes- and can affect wound healing. Potential uses of cytokines include cancer and antiviral therapy.

Chemokines↗
PubMed1996

A novel endogenous mediator of cutaneous inflammation: leukemia inhibitory factor.

Keratinocytes produce a variety of cytokines, including leukemia inhibitory factor. We hypothesised that this cytokine may play a pro-inflammatory role in the skin and tested this hypothesis by injecting recombinant leukemia inhibitory factor (1-100 ng) into the ear pinnae of C3H/HeJ mice. To other groups of animals, we injected boiled leukemia inhibitory factor or phosphate-buffered saline (negative control) or 0.4 ng human interleukin-1 alpha as a positive control. Following injection of 100 ng leukemia inhibitory factor, ear thickness, measured by micrometer, increased 66% over controls at 12 h and 100% at 24 h (overall p = 0.041 by analysis of variance). Injection of 0.4 ng interleukin-1 alpha caused greater ear swelling. Compared with controls, swelling increased by 67% at 6 h, 100% at 12 h and 340% after 24 h (overall p < or = 0.00001). Leukemia inhibitory factor (100 ng only) stimulated a 3.5-fold increase in leukocytes after 6 h. After 12 h, a 14-fold increase was seen in ears injected with 10 ng leukemia inhibitory factor and a 12-fold increase with 100 ng leukemia inhibitory factor, which remained elevated (17-fold) at 24 h (overall p = 0.0001). Injection of interleukin-1 alpha led to a 3.4-fold increase in leukocytes (mean per 20 high-power fields) after 6 h, a 14-fold increase at 12 h and a 25-fold increase at 24 h (overall p < or = 0.00001). These results demonstrate that leukemia inhibitory factor appears to be a mediator of cutaneous inflammation.

Analysis of Variance↗
PubMed1996

The use of high-frequency ultrasound as a method of assessing the severity of a plaque of psoriasis.

BACKGROUND AND DESIGN: Ultrasound imaging, while initially developed to visualize internal organs, is now being applied to image the skin. In this preliminary study, we used a high-frequency, 40-MHz ultrasound imaging system to provide high-resolution images in psoriasis and examined the relationship between clinical and ultrasound ratings in plaque-type psoriasis. The ultrasound image of a psoriatic plaque demonstrates a superficial echogenic band (band A), followed by a nonchogenic band (band B), and a deeper echogenic band (band C). RESULTS: In psoriatic plaques (N = 145), the severity of the psoriasis as assessed according to the degree of scaling, erythema, and thickness (SET score) correlated best with the width of band B (P < .001, r = 0.86) and less well with the width of bands A (P < .001, r = 0.59) and C (P < .001, r = 0.44). For the treated psoriatic plaques (n = 64), for which paired readings were available before and after therapy, changes in the SET scores correlated best with the change in the width of band B (P < .001, r = 0.96) and less well with the change in the width of bands A (P < .001, r = 0.61) and C (P < .001, r = 0.45). Ultrasound analyses and clinical evaluation were performed by independent raters. CONCLUSIONS: The data suggest that high-frequency ultrasound imaging may prove to be a noninvasive technique that can be used as an adjunct to the clinical evaluation of the lesional severity of psoriatic plaques.

Female↗
PubMed1996

Leukaemia inhibitory factor is expressed by normal human keratinocytes in vitro and in vivo.

Leukaemia inhibitory factor (LIF) is a pleotropic cytokine, regulating differentiation, cell growth, cachexia and inflammation. Using the reverse transcription-polymerase chain reaction (RT-PCR) we found that, in culture, normal human keratinocytes (KC) expressed mRNA transcripts for both LIF and the LIF receptor. In the conditioned medium (CM), constitutive LIF protein production was barely detectable but stimulation of KC with 10 ng/ml of either interleukin (IL)-1 alpha, or IL-8, for 24 h, resulted in small but significant increases (P < 0.05) in LIF protein, as measured by enzyme-linked immunosorbent assay. After culture in media containing 1.5 mmol/l calcium, a time-dependent increase in LIF mRNA was seen up to 72 h (an 8.5-fold increase), over levels in cells cultured in 0.05 mmol/l calcium. A large increase in LIF protein in the CM (from 1.15 +/- 0.15 pg/ml to 178.7 +/- 75.7 pg/ml) was seen 72 h after a switch to media containing 1.5 mmol/l calcium (P = 0.05). Twenty-four hours after stimulation of human KC in culture with 10 ng/ml recombinant LIF, a twofold increase in both IL-1 alpha and IL-8 protein in the CM (P < 0.05) was observed. In normal human scalp and foreskin, the epidermis was shown to contain LIF protein by immunostaining. LIF staining was found throughout the epidermis, and in the cells of the outer layer of the root sheath. Thus, KC synthesize LIF in vitro and in vivo.

Base Sequence↗
PubMed1996

Onychomycosis. New therapies for an old disease.

The newer generation of antifungal agents such as itraconazole and terbinafine are more effective than the older therapies, griseofulvin and ketoconazole, in the treatment of dermatophyte pedal onychomycosis. Itraconazole can be administered as continuous dosing, 200 mg per day for 3 months, or in the form of pulse therapy, 200 mg twice a day for 1 week per month for 3 consecutive months. Terbinafine is given as continuous dosing, 250 mg per day for 3 months.

Aged↗
PubMed1995

Effect of gene-targeted mutation in TNF receptor (p55) on contact hypersensitivity and ultraviolet B-induced immunosuppression.

Tumor necrosis factor alpha (TNF-alpha) is a pleiotropic proinflammatory cytokine. TNF-alpha has been implicated in the pathogenesis of delayed-type hypersensitivity reactions such as allergic contact hypersensitivity and has been suggested as a mediator of ultraviolet B (UVB)-induced immunosuppression. Conflicting reports, however, exist concerning the effects of TNF-alpha on contact hypersensitivity (CHS). To determine the role of TNF-alpha in the generation and regulation of CHS, gene-targeted mutant mice lacking TNF-receptor (p55) gene (TNF-R1(-) mice) were treated with dinitrofluorobenzene (DNFB) to induce CHS. TNF-R1(-) mice showed significant hyperresponsiveness in CHS (152.8 +/- 20.9%, p < 0.025) compared with normal syngeneic mice (C57BL/6) assessed by ear swelling. To determine whether UVB can induce suppression in TNF-R1(-) mice, mice were irradiated on the shaved abdomen with 96 mj/cm2 UVB and 3 days later they were painted with 0.5% DNFB (sensitization dose), followed 5 days later with 0.2% DNFB to the left ear (challenge dose). Significant suppression of CHS was observed both locally (sensitization on irradiated site) and systemically (sensitization on unirradiated site) in UVB-irradiated TNF-R1(-) mice as well as in normal mice. To rule out possible signaling through p75 TNF-R, the mice were treated with anti-TNF-alpha Ab (V1q), which can neutralize any TNF effects through either receptor. V1q had no effect on these phenomena observed in TNF-R1(-) mice. These results suggest that TNF-alpha plays a regulatory role in CHS but is not required to induce UVB-mediated immunosuppression.

Animals↗
PubMed1995

The role of cis-urocanic acid in UVB-induced suppression of contact hypersensitivity.

Ultraviolet light B (UVB) is well recognized to suppress the contact hypersensitivity (CHS) response and it has been postulated that cis-urocanic acid (UCA) is a mediator of the immunosuppression. This study was designed to examine the effect of UCA on CHS and to clarify its role in UVB-induced immunosuppression in C57BL/6 mice. Intradermal injection of 0.5-50 micrograms cis-UCA into the ear 2 h before DNFB sensitization resulted in a 60-70% reduction of CHS assessed by ear swelling, whereas trans-UCA did not have a significant effect on CHS except at a high dose (50 micrograms) which showed a 20-40% suppression. Intraperitoneal injection of anti-cis-UCA antibody before administration of cis-UCA abrogated the suppression. To examine the effect of UCA on UVB-induced immunosuppression, some mice were pre-treated with anti-cis-UCA antibody and then exposed to UVB (960 J/m2). After 3 days the mice were sensitized either on the irradiated abdominal skin or on the unirradiated dorsal surface of the right ear followed by the challenge on the left ear. The CHS response was significantly suppressed in UVB-irradiated mice both locally (abdominal sensitization, suppression was 45%, P < 0.001) and systemically (ear sensitization, suppression was 53%, P < 0.0025). The CHS response was partially restored in both abdominal sensitized mice and ear sensitized mice by pre-treatment with anti-cis-UCA antibody. These results confirmed the immunosuppressive effects of cis-UCA on CHS and suggest that cis-UCA plays a role in UVB-induced local and systemic immunosuppression.

Animals↗
PubMed1995

Epidermal cytokines in allergic contact dermatitis.

The understanding of cutaneous immunology has grown significantly during the past decade, particularly regarding the immune function of keratinocytes. Keratinocytes play a major role in immune and inflammatory reactions, mainly through synthesis and release of cytokines. The cytokine network in the skin is an important contributor to normal homeostasis and to the pathogenesis of cutaneous disease. Although cytokine dysregulation has been implicated in the pathogenesis of many cutaneous diseases, allergic contact dermatitis is one that has been the most extensively studied. The aim of this article is to provide a comprehensive current review of the mechanisms of allergic contact dermatitis with particular emphasis on the role of epidermal cytokines.

Cytokines↗