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Biomedical subjects

C A Elmets

Publications and source records attributed to C A Elmets.

At least 19 recordsLinked to original sources
PubMed2001

Green tea polyphenols: DNA photodamage and photoimmunology.

Green tea is a popular beverage consumed worldwide. The epicatechin derivatives, which are commonly called 'polyphenols', are the active ingredients in green tea and possess antioxidant, anti-inflammatory and anti-carcinogenic properties. Studies conducted by our group on human skin have demonstrated that green tea polyphenols (GTP) prevent ultraviolet (UV)-B-induced cyclobutane pyrimidine dimers (CPD), which are considered to be mediators of UVB-induced immune suppression and skin cancer induction. GTP treated human skin prevented penetration of UV radiation, which was demonstrated by the absence of immunostaining for CPD in the reticular dermis. The topical application of GTP or its most potent chemopreventive constituent (-)-epigallocatechin-3-gallate (EGCG) prior to exposure to UVB protects against UVB-induced local as well as systemic immune suppression in laboratory animals. Additionally, studies have shown that EGCG treatment of mouse skin inhibits UVB-induced infiltration of CD11b+ cells. CD11b is a cell surface marker for activated macrophages and neutrophils, which are associated with induction of UVB-induced suppression of contact hypersensitivity responses. EGCG treatment also results in reduction of the UVB-induced immunoregulatory cytokine interleukin (IL)-10 in skin as well as in draining lymph nodes, and an elevated amount of IL-12 in draining lymph nodes. These in vivo observations suggest that GTPs are photoprotective, and can be used as pharmacological agents for the prevention of solar UVB light-induced skin disorders associated with immune suppression and DNA damage.

Animals↗
PubMed2001

The role of ICAM-1 molecule in the migration of Langerhans cells in the skin and regional lymph node.

ICAM-1 (CD54) plays an important role in the cell-cell interaction and migration of leukocytes. Previous studies have shown that ICAM-1 is involved in inflammatory reactions and that a defect in ICAM-1 gene inhibits allergic contact hypersensitivity. This study indicates that the migration of hapten presenting Langerhans cells into the regional lymph nodes was significantly reduced in ICAM-1-deficient mice compared to wild-type C57BL/6 mice. The reduced number of dendritic cells in regional lymph nodes did not result from abnormal migration of Langerhans cells into the skin of ICAM-1-deficient mice. The concentration and distribution of Langerhans cells in the naïve skin of ICAM-1-deficient mice was equal to that of wild-type mice. Following hapten sensitization, Langerhans cell migration out of the skin and recruitment of fresh Langerhans cells back to the epidermis was not affected in ICAM-1-deficient mice. Further experiments demonstrated that ICAM-1 deficiency on lymphatic endothelium rather than on dendritic cells was responsible for the reduced migration of Langerhans cells into draining lymph nodes. This study indicates that ICAM-1 regulates the migration of dendritic cells into regional lymph nodes but not into or out of the skin.

Animals↗
PubMed2001

Cutaneous photoprotection from ultraviolet injury by green tea polyphenols.

BACKGROUND: In animal models, extracts from green tea have been shown to be remarkably effective at reducing the severity of adverse human health effects of overexposure to ultraviolet (UV) radiation. Although sunscreens and other photoprotective measures have traditionally been used for this purpose, there is a need for additional measures and natural products are increasingly being explored for that purpose. OBJECTIVE: Our purpose was to evaluate the effect of polyphenols from green tea on parameters associated with acute UV injury. METHODS: Areas of skin of normal volunteers were treated with an extract of green tea or one of its constituents. Thirty minutes later, the treated sites were exposed to a 2 minimal erythema dose solar simulated radiation. UV-treated skin was examined clinically for UV-induced erythema, histologically for the presence of sunburn cells or Langerhans cell distributions, or biochemically for UV-induced DNA damage. RESULTS: Application of green tea extracts resulted in a dose-dependent inhibition of the erythema response evoked by UV radiation. The (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) polyphenolic fractions were most efficient at inhibiting erythema, whereas (-)-epigallocatechin (EGC) and (-)-epicatechin (EC) had little effect. On histologic examination, skin treated with green tea extracts reduced the number of sunburn cells and protected epidermal Langerhans cells from UV damage. Green tea extracts also reduced the DNA damage that formed after UV radiation. CONCLUSION: Polyphenolic extracts of green tea are effective chemopreventive agents for many of the adverse effects of sunlight on human health and may thus serve as natural alternatives for photoprotection.

Administration, Topical↗
PubMed2001

A phase III, randomized, double-blind, placebo-controlled study of peldesine (BCX-34) cream as topical therapy for cutaneous T-cell lymphoma.

BACKGROUND: The purine nucleoside phosphorylase inhibitor peldesine is a new agent being evaluated as a T-cell inhibitor. OBJECTIVE: We attempted to determine the efficacy of peldesine (BCX-34) in a 1% dermal cream formulation as a treatment for cutaneous T-cell lymphoma (CTCL). METHODS: Ninety patients with patch and plaque phase CTCL, histologically confirmed by a referee dermatopathologist, were enrolled in a randomized, double-blind, placebo-controlled study. BCX-34 dermal cream 1% or the vehicle cream (as a placebo control) was applied twice daily to the entire skin surface for up to 24 weeks. Efficacy of the topical therapy was assessed in terms of complete or partial (> or = 50%) clearing of patches and plaques. RESULTS: Of the 89 patients able to be examined, 43 received BCX-34 and 46 received the placebo vehicle cream. One patient withdrew early and was not analyzed. The two groups were well balanced for potential prognostic factors. A total of 28% (12/43) of the patients treated with BCX-34 showed a response, but 24% (11/46) of patients who received vehicle also responded (P =.677). CONCLUSION: Although BCX-34 dermal cream 1% was not significantly better than the control as therapy for patch and plaque-phase CTCL, this appears to be the first published placebo-controlled trial evaluating treatment for CTCL. Whether the vehicle cream has more than a placebo therapeutic effect is unclear. The relatively high (24%) placebo response rate should be kept in mind in assessing other treatments for early-stage CTCL.

Administration, Cutaneous↗
PubMed2001

Protection against tetanus by needle-free inoculation of adenovirus-vectored nasal and epicutaneous vaccines.

The effectiveness of vaccination programs would be enhanced greatly through the availability of vaccines that can be administered simply and, preferably, painlessly without the need for timed booster injections. Tetanus is a prime example of a disease that is readily preventable by vaccination but remains a major threat to public health due to the problems associated with administration of the present vaccine. Here we show that a protective immune response against live Clostridium tetani infection in mice can be elicited by an adenovirus vector encoding the tetanus toxin C fragment when administered as a nasal or epicutaneous vaccine. The results suggest that these vaccination modalities would be effective needle-free alternatives. This is the first demonstration that absorption of a small number of vectored vaccines into the skin following topical application of a patch can provide protection against live bacteria in a disease setting.

Adenoviridae↗
PubMed2001

Green tea polyphenolic antioxidants and skin photoprotection (Review).

Green tea is consumed as a popular beverage worldwide particularly in Asian countries like China, Korea, Japan and India. It contains polyphenolic compounds also known as epicatechins, which are antioxidant in nature. Many laboratories have shown that topical treatment or oral consumption of green tea polyphenols inhibits chemical carcinogen- or ultraviolet radiation-induced skin tumorigenesis in different animal models. Studies have shown that green tea extract also possesses anti-inflammatory activity. These anti-inflammatory and anti-carcinogenic properties of green tea are due to their polyphenolic constituents present therein. The major and most chemopreventive constituent in green tea responsible for these biochemical or pharmacological effects is (-)-epigallocatechin-3-gallate (EGCG). Understanding the molecular mechanisms of these effects of green tea is a subject of investigation in many laboratories. Treatment of green tea polyphenols to skin has been shown to modulate the biochemical pathways involved in inflammatory responses, cell proliferation and responses of chemical tumor promoters as well as ultraviolet (UV) light-induced inflammatory markers of skin inflammation. Topical treatment with EGCG on mouse skin also results in prevention of UVB-induced immunosuppression, and oxidative stress. The protective effects of green tea treatment on human skin either topically or consumed orally against UV light-induced inflammatory or carcinogenic responses are not well understood. Based on documented extensive beneficial effects of green tea on mouse skin models and very little in human skin, many pharmaceutical and cosmetic companies are supplementing their skin care products with green tea extracts. Therefore, the focus of this communication is to review and analyze the photoprotective effects of green tea polyphenols to skin.

Anti-Inflammatory Agents↗
PubMed2000

Sensitization versus elicitation in allergic contact dermatitis: potential differences at cellular and molecular levels.

The induction and elicitation phases of allergic contact dermatitis are very complicated processes that differ in many respects. Many issues remain to be investigated, especially in the elicitation phase of this disease. Several key molecules involved in the development and maintenance of allergic contact dermatitis have already been defined, including a number of different cytokines and adhesion molecules. Attempts are being made to develop new, more specific pharmacologic and immunologic inhibitors of their activity. Because patients who see a doctor are already sensitized, further elucidation of the factors affecting the elicitation of allergic contact dermatitis will greatly contribute to the prevention and treatment of the disease.

Cell Adhesion Molecules↗
PubMed1999

Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin.

Identification of natural products capable of affording protection against UVB radiation-induced inflammatory responses and generation of oxidative stress may have important human health implications. The UVB exposure-induced skin injury and oxidative stress has been associated with a variety of skin disease conditions including photoaging, inflammation and cancer. Tea is a popular beverage consumed worldwide. In several mouse skin models, topical application as well as oral consumption of green tea has been shown to afford protection against chemical and UVB-induced carcinogenesis and inflammatory responses. In the present study, we investigated in human skin, whether topical application of (-)-epigallocatechin-3-gallate (EGCG), the major polyphenolic constituent in green tea, inhibits UVB-induced infiltration of leukocytes (macrophage/neutrophils), a potential source of generation of reactive oxygen species (ROS), and generation of prostaglandin (PG) metabolites. Human subjects were UVB irradiated on sun-protected skin to four times their minimal erythema dosage (MED) and skin biopsies or keratomes were obtained either 24 h or 48 h later. We found that topical application of EGCG (3 mg/2.5 cm2) before UVB (4 MED) exposure to human skin significantly blocked UVB-induced infiltration of leukocytes and reduced myeloperoxidase activity. These infiltrating leukocytes are considered to be the major source of generation of ROS. In the same set of experiments we found that topical application of EGCG before UVB exposure decreased UVB-induced erythema. In additional experiments, we found that microsomes from EGCG pretreated human skin and exposed to UVB, compared to UVB exposure alone, produced significantly reduced PG metabolites, particularly PGE2. The PG metabolites play a critical role in free radical generation and skin tumor promotion in multistage skin carcinogenesis. Careful microscopic examination of skin sections, stained with hematoxylin and eosin, under higher magnification (x400) also revealed that EGCG pretreated and UVB-exposed human skin contained fewer dead cells in the epidermis with comparison to nonpretreated UVB-exposed skin. Taken together, our data demonstrate that EGCG has the potential to block the UVB-induced infiltration of leukocytes and the subsequent generation of ROS in human skin. This may explain the possible mechanism involved in anti-inflammatory effects of green tea. We suggest that EGCG may be useful as a topical agent for protection against UVB-induced ROS-associated inflammatory dermatoses, photoaging and photocarcinogenesis. Further studies are warranted in this direction.

Animals↗
PubMed1999

Phthalocyanine 4 (Pc 4) photodynamic therapy of human OVCAR-3 tumor xenografts.

Photodynamic therapy (PDT) is a cancer treatment modality utilizing a photosensitizer, light and oxygen. Photodynamic therapy with Photofrin has been approved by the U.S. Food and Drug Administration for treatment of advanced esophageal and early lung cancer. Because of certain drawbacks associated with the use of Photofrin, there is a need to identify new photosensitizers for human use. The photosensitizer Pc 4 (HOSiPc-OSi[CH3]2[CH2]3N[CH3]2) has yielded promising PDT effects in many in vitro and in vivo systems. The aim of this study was to assess the usefulness of Pc 4 as a PDT photosensitizer for a human tumor grown as a xenograft in athymic nude mice. The ovarian epithelial carcinoma (OVCAR-3) was heterotransplanted subcutaneously in athymic nude mice. Sixty mice bearing OVCAR-3 tumors (approximately 80-130 mm3) were divided into six groups of 10 animals each, three for controls and three for treatment. The Pc 4 was given by tail vein injection, and 48 h later a 1 cm area encompassing the tumor was irradiated with light from a diode laser coupled to a fiberoptic terminating in a microlens (lambda = 672 nm, 150 J/cm2, 150 mW/cm2). Tumors of control animals receiving no treatment, light alone or Pc 4 alone continued to grow. Of animals receiving 0.4 mg/kg Pc 4 and light, one (10%) had a complete response and was cured (no regrowth up to 90 days post-PDT), while all others (90%) had a partial response and were delayed in regrowth. Of animals receiving 0.6 mg/kg Pc 4 and light, eight (80%) had a complete response, and two of these were cured. Of animals receiving 1.0 mg/kg Pc 4 and light, six (60%) had a complete response, and two of these were cured. In additional experiments, tumors from animals treated with Pc 4 (1 mg/kg) and light were removed 15, 30, 60 and 180 min post-PDT, and from these tumors DNA and protein were extracted. Agarose gel electrophoresis revealed the presence of apoptotic DNA fragmentation as early as 15 min post-PDT. Western blotting showed the cleavage of the 116 kDa native poly(ADP-ribose) polymerase (PARP) into fragments of approximately 90 kDa, another indication of apoptosis, and the presence of p21/WAF1/CIP1 (p21) in all PDT-treated tumors. These changes did not occur in control tumors. Pc 4 appears to be an effective photosensitizer for PDT of human tumors grown as xenografts in nude mice. Early apoptosis, as revealed by PARP cleavage, DNA fragmentation and p21 overexpression, may be responsible for the excellent Pc 4-PDT response. Clinical trials of Pc 4-PDT are warranted.

Animals↗
PubMed1999

Immunosuppressive effects of silicon phthalocyanine photodynamic therapy.

The purpose of this study was to determine if silicon phthalocyanine 4 (Pc 4), a second-generation photosensitizer being evaluated for the photodynamic therapy (PDT) of solid tumors, was immunosuppressive. Mice treated with Pc 4 PDT 3 days before dinitrofluorobenzene sensitization showed significant suppression of their cell-mediated immune response when compared to mice that were not exposed to PDT. The response was dose dependent, required both Pc 4 and light and occurred at a skin site remote from that exposed to the laser. The immunosuppression could not be reversed by in vivo pre-treatment of mice with antibodies to tumor necrosis factor-alpha or interleukin-10. These results provide evidence that induction of cell-mediated immunity is suppressed after Pc 4 PDT. Strategies that prevent PDT-mediated immunosuppression may therefore enhance the efficacy of this therapeutic modality.

Animals↗
PubMed1998

Susceptibility to the biological effects of polyaromatic hydrocarbons is influenced by genes of the major histocompatibility complex.

Polyaromatic hydrocarbons are ubiquitous environmental chemicals that are important mutagens and carcinogens. The purpose of this study was to determine whether genes within the major histocompatibility complex (MHC) influence their biological activities. Cell-mediated immunity to dimethylbenz(a)anthracene (DMBA) was investigated in congenic strains of mice. On three different backgrounds, H-2(k) and H-2(a) haplotype mice developed significantly greater contact-hypersensitivity responses to DMBA than H-2(b), H-2(d), and H-2(s) mice. In B10.A(R1) mice, which are Kk and Id, a vigorous contact-hypersensitivity response was present, indicating that the response was governed by class I, rather than class II, MHC genes. C3H/HeN (H-2(k)) and C3H.SW (H-2(s)) strains were also compared for the development of skin tumors and the persistence of DMBA-DNA adducts. When subjected to a DMBA initiation, phorbol 12-tetradecanoate 13-acetate (TPA)-promotion skin-tumorigenesis protocol, C3H/HeN mice, (which develop cell-mediated immunity to DMBA) were found to have significantly fewer tumors than C3H.SW mice (a strain that failed to develop a cell-mediated immune response to DMBA). DMBA-DNA adducts were removed more rapidly in C3H/HeN than in C3H.SW mice. The results indicate that genes within the MHC play an important role in several of the biological activities of carcinogenic polyaromatic hydrocarbons. The observations are consistent with the hypothesis that cell-mediated immunity to chemical carcinogens serves to protect individuals by removing mutant cells before they can evolve into clinically apparent neoplasms.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

A comparative analysis of silicon phthalocyanine photosensitizers for in vivo photodynamic therapy of RIF-1 tumors in C3H mice.

Photofrin photodynamic therapy (PDT) has recently received FDA approval for the palliative treatment of totally and partially obstructing esophageal malignancies. However, there is a need for new PDT photosensitizers because Photofrin has a number of undesirable features. The purpose of this study was to evaluate the efficacy of four amine-bearing silicon phthalocyanines--Pc4, Pc10, Pc12 and Pc18--as potential PDT photosensitizers. Equimolar concentrations of these Pc were found to be highly effective at causing the regression of RIF-1 tumors transplanted to C3H/HeN mice. The amount of Pc4 necessary to cause an equivalent amount of tumor regression in this model system was substantially less than the amount of Photofrin. The cutaneous phototoxicity of the silicon Pc photosensitizer was assessed by the utilization of the murine ear-swelling model. When C3H mice were exposed to 167 J/cm2 of polychromatic visible light from a UVB-filtered solar simulator, which emitted UV radiation and visible light above 320 nm, the Pc produced little, if any, cutaneous photosensitivity. These results indicate that Pc4, Pc10, Pc12 and Pc18 are at least as effective as Photofrin in PDT protocols, while at the same time addressing many of the drawbacks of Photofrin.

Animals↗
PubMed1997

Induction of biologically active IL-1 beta-converting enzyme and mature IL-1 beta in human keratinocytes by inflammatory and immunologic stimuli.

IL-1beta, a major mediator of inflammatory and immunologic skin disease, undergoes post-translational site-specific cleavage by a novel cysteine protease termed IL-1beta-converting enzyme (ICE). Although in human skin keratinocytes produce significant amounts of the 31-kDa IL-1beta precursor protein, they fail under nonpathologic conditions to convert it to the 17.5-kDa bioactive form. In this study, we examined whether haptens and inflammatory agents might serve as stimuli for ICE activity in human keratinocytes, and, if so, whether ICE activity might precipitate enzymatic processing of IL-1beta to its 17.5-kDa form. Baseline levels of ICE mRNA were detected in keratinocyte cultures devoid of Langerhans cells and were up-regulated by nontoxic concentrations of the reactive hapten urushiol and by the irritant chemicals sodium lauryl sulfate and PMA. Although untreated keratinocytes expressed the 31-kDa form of the protein, 17.5-kDa IL-1beta was easily detected in keratinocytes and keratinocyte supernatants treated with either urushiol or the irritant chemicals. Enzymatic conversion from the 31-kDa to the 17.5-kDa form of IL-1beta was blocked by addition of a highly specific aldehyde inhibitor that contained a tetrapeptide recognition sequence specific for ICE, but not by an aldehyde inhibitor of a related ICE-like cysteine protease. Induction of IL-1beta-converting enzyme by immunologic and inflammatory stimuli may be one of the key regulatory elements in the pathogenesis of allergic and irritant contact hypersensitivity.

Caspase 1↗
PubMed1997

High incidence of Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus in tumor lesions and peripheral blood mononuclear cells from patients with Kaposi's sarcoma in Uganda.

With the advent of AIDS, Kaposi's sarcoma (KS) has become one of the leading malignancies in sub-Saharan Africa. Recently, DNA sequences from a new human herpesvirus called KS-associated herpesvirus (KSHV) or human herpesvirus type 8 have been found in KS tumor lesions in high frequency. Analyses of tumor lesions from 38 Ugandan KS patients indicated a uniform presence of KSHV in KS tumor lesions as revealed by polymerase chain reaction and Southern hybridization. In contrast, only 31% (11/36) of the normal skin biopsies from the same patient population were positive. The frequency of KSHV DNA detection in peripheral blood mononuclear cells (PBMC) of KS patients was also high (84%, 31/37). Similar analyses revealed the presence of cytomegalovirus (21% in KS lesions) to be discordant with KS development. A large number of KS lesions (87%, 33/38) and KS PBMC (70%, 26/37) were, however, positive for Epstein-Barr virus sequences. In addition, KSHV DNA was not found in the PBMC of Ugandans without KS.

Adult↗
PubMed1997

Genetic variation in low-dose UV-induced suppression of contact hypersensitivity and in the skin photocarcinogenesis response.

Two of the major cutaneous consequences of ultraviolet (UV) radiation exposure are immunosuppression and the development of skin cancer. This study examined whether these effects are genetically determined. Suppression of contact hypersensitivity by local, low-dose UV radiation was examined in what have been termed "UV-susceptible" and "UV-resistant" strains of mice. C3H/HeJ mice ("UV resistant") were resistant to the adverse effects of low-dose UV radiation when normal doses of hapten were applied to UV-irradiated skin; however, they were sensitive when the amount of hapten used for sensitization was reduced. A similar effect was observed in BALB/c mice ("UV resistant") and when the hapten was dimethylbenz(a)anthracene, thus indicating that the genetic variation was not strain or hapten specific. Despite the fact that some strains were sensitive and some were resistant to low-dose UV radiation when high doses of hapten were employed, all strains initially sensitized to hapten through UV-irradiated skin were found to be unresponsive when rechallenged on normal skin, no matter what the initial sensitizing dose of hapten was. To determine whether other biologic effects of UV also exhibited genetic variation, C3H/HeN and C3H/HeJ mice were compared for susceptibility to UVB-induced skin cancer formation. C3H/HeJ mice developed significantly more tumors than C3H/HeN mice when subjected to a single dose of UV radiation followed by repeated exposure to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. These studies provide strong evidence that genetic factors influence individual susceptibility to the biologic effects of UV radiation.

Animals↗
PubMed1997

ICAM-1 mRNA levels and relative transcription rates are decreased by UV irradiation of monocytes.

We have previously demonstrated that in vitro exposure of antigen-presenting cells to UVB radiation inhibits their ability to activate T cells through selective effects on the expression of the adhesion molecule ICAM-1 (intercellular adhesion molecule-1). Intercellular adhesion molecule-1 is an important costimulatory molecule provided by antigen-presenting cells for T-cell activation. Using human peripheral blood monocytes and the U937 human monocytoid cell line as model antigen-presenting cells, we investigated the effect of UV radiation on the mRNA steady-state levels for human ICAM-1 by northern blot analysis and relative transcription rates of ICAM-1-specific mRNA by nuclear run-on assay (NRO). Northern blot analysis demonstrated a decreased level of ICAM-1 mRNA at 4 h postradiation relative to glyceraldehyde-3-dehydrogenase mRNA. The NRO analysis demonstrated a greater than 35% decrease of newly synthesized specific mRNA at 4 h postirradiation. The results demonstrate a transcriptionally based mechanism for the diminution of both mRNA and translatable mRNA specific for ICAM-1 regulation in UV-treated antigen-presenting cells.

Cell Line↗