Costaria costata Extract Suppresses Development of Atopic Dermatitis in chloro-2,4-dinitrobenzene-treated NC/Nga Mice.

We investigated the potential effects of Costaria costata (CC) on atopic dermatitis (AD) development in chloro-2,4-dinitrobenzene (DNCB)-treated NC/Nga mice. CC is a brown alga distributed across the seas of Korea, China, and Japan. A total of 40 mice were randomly assigned to 5 groups with 8 mice per group: untreated Balb/c mice, AD control (0.1% w/v DNCB-treated NC/Nga mice), positive control (i.e., DNCB-treated NC/Nga mice fed a dietary supplement of 66.6 mg/kg of body weight [b.w.] of CJLP133), DNCB-treated NC/Nga mice fed a dietary supplement of 100 mg/kg b.w. of CCE10 (CCE10 100), and DNCB-treated mice fed a dietary supplement of 300 mg/kg b.w. of CCE10 (CCE10 300) groups. The CCE10 100 and CCE10 300 treatment groups suppressed AD development including clinical and histopathological changes and a reduction in skin hydration induced by DNCB. In addition, Th2 cytokine production in primary splenocytes, serum IgE and histamine production, and mast cell infiltration into the skin were suppressed in the CCE10 300 mice compared to the CCE10 100 mice. Our finding demonstrated an inhibitory effect of CCE10 in AD development by means of improving the Th1/Th2 cytokine balance and anti-inflammatory effect in an in vivo model.

GPCR Kinase (GRK)-2 Is a Key Negative Regulator of Itch: l-Glutamine Attenuates Itch via a Rapid Induction of GRK2 in an ERK-Dependent Way.

Many itch mediators activate GPCR and trigger itch via activation of GPCR-mediated signaling pathways. GPCRs are desensitized by GPCR kinases (GRKs). The aim of this study is to explore the role of GRKs in itch response and the link between GRKs and glutamine, an amino acid previously shown to be an itch reliever. Itch responses were evoked by histamine, chloroquine, and dinitrochlorobenzene-induced contact dermatitis (CD). Phosphorylation and protein expression were detected by immunofluorescent staining and Western blotting. GRK2 knockdown using small interfering RNA enhanced itch responses evoked by histamine, chloroquine, and dinitrochlorobenzene-induced CD, whereas GRK2 overexpression using GRK2-expressing adenovirus reduced the itch responses. Glutamine reduced all itch evoked by histamine, chloroquine, and dinitrochlorobenzene-induced CD. Glutamine-mediated inhibition of itch was abolished by GRK2 knockdown. Glutamine application resulted in a rapid and strong expression of GRK2 in not only dinitrochlorobenzene-induced CD (within 10 minutes) but also cultured rat dorsal root ganglion cells, F11 (within 1 minute). ERK inhibitor abrogates glutamine-mediated GRK2 expression and inhibition of itch in dinitrochlorobenzene-induced CD. Our data indicate that GRK2 is a key negative regulator of itch and that glutamine attenuates itch via a rapid induction of GRK2 in an ERK-dependent way.

The thioredoxin and glutathione-dependent H2O2 consumption pathways in muscle mitochondria: Involvement in H2O2 metabolism and consequence to H2O2 efflux assays.

The most common methods of measuring mitochondrial hydrogen peroxide production are based on the extramitochondrial oxidation of a fluorescent probe such as amplex ultra red (AUR) by horseradish peroxidase (HRP). These traditional HRP-based assays only detect H2O2 that has escaped the matrix, raising the potential for substantial underestimation of production if H2O2 is consumed by matrix antioxidant pathways. To measure this underestimation, we characterized matrix consumers of H2O2 in rat skeletal muscle mitochondria, and developed specific means to inhibit these consumers. Mitochondria removed exogenously added H2O2 (2.5µM) at rates of 4.7 and 5.0nmol min(-1) mg protein(-1) when respiring on glutamate+malate and succinate+rotenone, respectively. In the absence of respiratory substrate, or after disrupting membranes by cycles of freeze-thaw, rates of H2O2 consumption were negligible. We concluded that matrix consumers are respiration-dependent (requiring respiratory substrates), suggesting the involvement of either the thioredoxin (Trx) and/or glutathione (GSH)-dependent enzymatic pathways. The Trx-reductase inhibitor auranofin (2µM), and a pre-treatment of mitochondria with 35µM of 1-chloro-2,4-dintrobenzene (CDNB) to deplete GSH specifically compromise these two consumption pathways. These inhibition approaches presented no undesirable "off-target" effects during extensive preliminary tests. These inhibition approaches independently and additively decreased the rate of consumption of H2O2 exogenously added to the medium (2.5µM). During traditional HRP-based H2O2 efflux assays, these inhibition approaches independently and additively increased apparent efflux rates. When used in combination (double inhibition), these inhibition approaches allowed accumulation of (endogenously produced) H2O2 in the medium at a comparable rate whether it was measured with an end point assay where 2.5µM H2O2 is initially added to the medium or with traditional HRP-based efflux assays. This finding confirms that a high degree of inhibition of all matrix consumers is attained with the double inhibition. Importantly, this double inhibition of the matrix consumers allowed revealing that a large part of the H2O2 produced in muscle mitochondria is consumed before escaping the matrix during traditional HRP-based efflux assays. The degree of this underestimation was substrate dependent, reaching >80% with malate, which complicates comparisons of substrates for their capacity to generate H2O2 in normal conditions i.e. when matrix consumers are active. Our results also urge caution in interpreting changes in H2O2 efflux in response to a treatment; when HRP-based assays are used, large changes in apparent H2O2 efflux may come from altered capacity of the matrix consumers.

Oral administration of herbal mixture extract inhibits 2,4-dinitrochlorobenzene-induced atopic dermatitis in BALB/c mice.

CP001 is four traditional herbal medicine mixtures with anti-inflammatory properties. In this study, we investigated the effect of oral administration of CP001 ethanol extract on the 2,4-dinitrochlorobenzene- (DNCB-) induced AD mouse models. For that purpose, we observed the effects of oral administration of CP001 on skin inflammatory cell infiltration, skin mast cells, production of serum IgE, and expression of Th2 cytokine mRNA in the AD skin lesions of DNCB treated BALB/c mice. Histological analyses demonstrated that CP001 decreased dermis and epidermis thickening as well as dermal infiltration induced by inflammatory cells. In addition, CP001 decreased mast cell infiltration in count as well as dermal infiltration induced by inflammatory cells. In the skin lesions, mRNA expression of interleukin- (IL-) 4 and IL-13 was inhibited by CP001. CP001 also reduced the production of IgE level in mouse plasma. In addition, we investigated the effect of CP001 on the inflammatory allergic reaction using human mast cells (HMC-1). In HMC-1, cytokine production and mRNA levels of IL-4, IL-13, IL-6, and IL-8 were suppressed by CP001. Taken together, our results showed that oral administration of CP001 exerts beneficial effects in AD symptoms, suggesting that CP001 might be a useful candidate for the treatment of AD.

Impact of the magnitude of sensitization dose on the incidence and intensity of CHS to dinitrochlorobenzene (DNCB): insight from ear swelling and challenged-skin draining lymph node response in rats.

Allergic contact dermatitis (ACD) is a common skin inflammatory disease that develops in hosts sensitized with contact allergens. Elucidation of dose-response relationships represents one of the approaches in studying the type of ACD in humans/animal models, termed as contact hyper-sensitivity reaction (CHS). Such studies have demonstrated that the intensity of sensitization determines the response to elicitation with a contact allergen, but underlying mechanisms are unclear. The aim of this study is to explore the impact of the sensitization on contact hypersensitivity to dinitrochlorobenzene (DNCB) in rats by measuring the incidence and intensity of a challenge response in hosts sensitized with two different doses (i.e. low and high) of this hapten. Assumptions concerning the contribution from the magnitude of sensitization doses were drawn on the basis of effects from the two doses on the measured reaction parameters. Ear swelling and activity of lymph nodes that drain challenged skin (cdLN), including cellularity, proliferation, and effector cytokine IFNγ and IL-17 production was measured in rats sensitized with 0.4% or 4% DNCB and challenged with a non-irritant (0.13%) dose. Sensitization with 4% DNCB resulted in a greater proportion of rats who responded more intensely (than unsensitized challenged rats) to challenge in terms of ear swelling and increases in cdLN activity (except for IFNγ). The intensity of cdLN responses was higher in these hosts as well. Among the high-dose-sensitized rats, greater cellularity/proliferation of cells from lymph nodes (sdLN) that drain the high-dose-sensitized skin, as well as higher IL-17 production, was noted compared to what was seen in rats that received low-dose sensitization. In contrast, unchanged spontaneous and even decreased hapten-stimulated IFNγ production after the high DNCB dose was observed. Based on the data, it seems the impact of magnitude of sensitization dose on CHS might be related to the rise in the proportion of rats that responded to challenge with an increase of dLN activity. Coincidental higher production of IL-17 by dLN cells from the high-dose-sensitized rats and following challenge of these hosts underscored the significance of IL-17 for a CHS to DNCB.

Sensitization via healthy skin programs Th2 responses in individuals with atopic dermatitis.

Allergen-specific responses in atopic dermatitis (AD) are skewed toward a Th2 profile. However, individuals with AD have been shown to make effective virus-specific Th1 responses, raising the possibility that the skin itself contributes to driving the AD Th2 immunophenotype. Therefore, to explore the programming of immunological sensitization by the skin, we examined the outcome of sensitization through non-lesional skin of individuals with AD and healthy controls. Volunteers (controls, AD individuals with filaggrin gene (FLG) mutations (ADFM), and AD individuals without FLG mutations (ADWT)) were sensitized by cutaneous application of 2,4-dinitrochlorobenzene (DNCB), a small, highly lipophilic chemical sensitizer. At the doses tested, DNCB showed equal penetration into skin of all groups. Clinical reactions to DNCB were significantly reduced in AD. Although both controls and AD made systemic DNCB-specific Th1 responses, these were reduced in AD and associated with significantly Th2-skewed DNCB-specific T-cell responses. Th2 skewing was seen in both ADFM and ADWT, with no difference between these groups. After 3 months, DNCB-specific Th2 responses were persistent in individuals with AD, and Th1 responses persisted in controls. These data provide evidence that when antigen penetration is not limiting, AD skin has a specific propensity to Th2 programming, suggesting the existence of altered skin immune signaling that is AD-specific and independent of FLG status.

Topical treatments for cutaneous warts.

BACKGROUND: Viral warts are a common skin condition, which can range in severity from a minor nuisance that resolve spontaneously to a troublesome, chronic condition. Many different topical treatments are available. OBJECTIVES: To evaluate the efficacy of local treatments for cutaneous non-genital warts in healthy, immunocompetent adults and children. SEARCH METHODS: We updated our searches of the following databases to May 2011: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library, MEDLINE (from 2005), EMBASE (from 2010), AMED (from 1985), LILACS (from 1982), and CINAHL (from 1981). We searched reference lists of articles and online trials registries for ongoing trials. SELECTION CRITERIA: Randomised controlled trials (RCTs) of topical treatments for cutaneous non-genital warts. DATA COLLECTION AND ANALYSIS: Two authors independently selected trials and extracted data; a third author resolved any disagreements. MAIN RESULTS: We included 85 trials involving a total of 8815 randomised participants (26 new studies were included in this update). There was a wide range of different treatments and a variety of trial designs. Many of the studies were judged to be at high risk of bias in one or more areas of trial design.Trials of salicylic acid (SA) versus placebo showed that the former significantly increased the chance of clearance of warts at all sites (RR (risk ratio) 1.56, 95% CI (confidence interval) 1.20 to 2.03). Subgroup analysis for different sites, hands (RR 2.67, 95% CI 1.43 to 5.01) and feet (RR 1.29, 95% CI 1.07 to 1.55), suggested it might be more effective for hands than feet.A meta-analysis of cryotherapy versus placebo for warts at all sites favoured neither intervention nor control (RR 1.45, 95% CI 0.65 to 3.23). Subgroup analysis for different sites, hands (RR 2.63, 95% CI 0.43 to 15.94) and feet (RR 0.90, 95% CI 0.26 to 3.07), again suggested better outcomes for hands than feet. One trial showed cryotherapy to be better than both placebo and SA, but only for hand warts.There was no significant difference in cure rates between cryotherapy at 2-, 3-, and 4-weekly intervals.Aggressive cryotherapy appeared more effective than gentle cryotherapy (RR 1.90, 95% CI 1.15 to 3.15), but with increased adverse effects.Meta-analysis did not demonstrate a significant difference in effectiveness between cryotherapy and SA at all sites (RR 1.23, 95% CI 0.88 to 1.71) or in subgroup analyses for hands and feet.Two trials with 328 participants showed that SA and cryotherapy combined appeared more effective than SA alone (RR 1.24, 95% CI 1.07 to 1.43).The benefit of intralesional bleomycin remains uncertain as the evidence was inconsistent. The most informative trial with 31 participants showed no significant difference in cure rate between bleomycin and saline injections (RR 1.28, 95% CI 0.92 to 1.78).Dinitrochlorobenzene was more than twice as effective as placebo in 2 trials with 80 participants (RR 2.12, 95% CI 1.38 to 3.26).Two trials of clear duct tape with 193 participants demonstrated no advantage over placebo (RR 1.43, 95% CI 0.51 to 4.05).We could not combine data from trials of the following treatments: intralesional 5-fluorouracil, topical zinc, silver nitrate (which demonstrated possible beneficial effects), topical 5-fluorouracil, pulsed dye laser, photodynamic therapy, 80% phenol, 5% imiquimod cream, intralesional antigen, and topical alpha-lactalbumin-oleic acid (which showed no advantage over placebo).We did not identify any RCTs that evaluated surgery (curettage, excision), formaldehyde, podophyllotoxin, cantharidin, diphencyprone, or squaric acid dibutylester. AUTHORS' CONCLUSIONS: Data from two new trials comparing SA and cryotherapy have allowed a better appraisal of their effectiveness. The evidence remains more consistent for SA, but only shows a modest therapeutic effect. Overall, trials comparing cryotherapy with placebo showed no significant difference in effectiveness, but the same was also true for trials comparing cryotherapy with SA. Only one trial showed cryotherapy to be better than both SA and placebo, and this was only for hand warts. Adverse effects, such as pain, blistering, and scarring, were not consistently reported but are probably more common with cryotherapy.None of the other reviewed treatments appeared safer or more effective than SA and cryotherapy. Two trials of clear duct tape demonstrated no advantage over placebo. Dinitrochlorobenzene (and possibly other similar contact sensitisers) may be useful for the treatment of refractory warts.

Nano-titanium dioxide modulates the dermal sensitization potency of DNCB.

We determined the ability of a model nanoparticle (NP) (titanium dioxide, TiO(2)) to modulate sensitization induced by a known potent dermal sensitizer (dinitrochlorobenzene) using a variant of the local lymph node assay called lymph node proliferation assay.BALB/c mice received sub-cutaneous injections of vehicle (2.5 mM sodium citrate), TiO(2) NPs (0.004, 0.04 or 0.4 mg/ml) or pigment particles (0.04 mg/ml) both stabilized in sodium citrate buffer at the base of each ear (2x50µl), before receiving dermal applications (on both ears) of 2,4-Dinitrochlorobenzene (DNCB) (2x25µl of 0.1%) or its vehicle (acetone olive oil - AOO (4:1)) on days 0, 1 and 2. On day 5, the stimulation index (SI) was calculated as a ratio of (3)HTdR incorporation in lymphocytes from DNBC-treated mice and AOO-treated controls. In a second experiment the EC(3)-value for DNCB (0 to 0.1%) was assessed in the absence or presence of 0.04 mg/ml TiO(2). In a third experiment, the lymphocyte subpopulations and the cytokine secretion profile were analyzed after TiO(2) (0.04 mg/ml) and DNCB (0.1%) treatment. Injection of NPs in AOO-treated control mice did not have any effect on lymph node (LN) proliferation. DNCB sensitization resulted in LN proliferation, which was further increased by injection of TiO(2) NPs before DNCB sensitization. The EC(3) of DNCB, with prior injection of vehicle control was 0.041%, while injection with TiO(2) decreased the EC(3) of DNCB to 0.015%. TiO(2) NPs pre-treatment did not alter the lymphocyte subpopulations, but significantly increased the level of IL-4 and decreased IL-10 production in DNCB treated animals.In conclusion, our study demonstrates that administration of nano-TiO(2) increases the dermal sensitization potency of DNCB, by augmenting a Th(2) response, showing the immunomodulatory abilities of NPs.

Systemic immunomodulatory effects of topical dinitrochlorobenzene (DNCB) in rats. Activity of peripheral blood polymorphonuclear cells.

Topical application of dinitrochlorobenzene (DNCB) is employed in the immunotherapy of skin diseases. Activation of T-cell mediated immune responses (Th1/type1) is the supposed mechanism of the clinical effect of DNCB, but there are no data concerning innate/inflammatory mechanisms. In this study, the effect of repeated topical DNCB application on peripheral blood polymorphonuclear (PMN) leukocytes has been examined in two rat strains which differ in the propensity to mount Th1/type1 or Th2/type2 responses. The dynamics of changes in PMN numbers and effector activities (respiratory burst, nitric oxide production and myeloperoxidase content), as well as in adhesion and TNF-α production following the rat skin sensitization with low (0.4%) and high (4%) DNCB doses were measured. Both priming and activation of PMNs were observed following skin sensitization with DNCB, with dose-dependent as well as time-dependent differences in some PMN activities. Obtained data might be relevant for understanding the immune mechanisms of topical DNCB therapy.

Percutaneous toxicity of dinitrochlorobenzene (DNCB) in rats.

Contact hypersensitivity reaction (CHS) is a T-cell-mediated skin inflammatory reaction to cutaneous exposure to small sensitizing chemicals, haptens. While the significance of local inflammatory skin response to the hapten application in CHS induction and expression is known, there is paucity of data concerning systemic inflammation in CHS. In this study, changes in cellular (peripheral blood granulocytes) and humoral (plasma tumor necrosis factor (TNF)-α levels) components of inflammation during sensitization of rats with two consecutive applications of dinitrochlorobenzene (DNCB) were examined. The impact of sensitization on these parameters was determined by employing low (0.4%) and high (4%) hapten doses and by examining the dynamics (i.e. one and three days following the last application of DNCB) of these changes. Dose-dependent increase in relative numbers and priming (for respiratory burst and adhesion) effect of skin sensitization with DNCB on peripheral blood neutrophils in rats were noted. No changes in circulating TNF-α levels were observed following the sensitization. The increase in lung myeloperoxidase content and histologically evident presence of neutrophils was observed in lungs of the sensitized rats. The changes in granulocyte priming for adhesion might have accounted for the observed increase in lung neutrophil content in the sensitized rats.

Contact allergic response to dinitrochlorobenzene (DNCB) in rats: insight from sensitization phase.

Contact hypersensitivity (CHS) is a T-cell-mediated skin inflammatory reaction to cutaneous exposure to small sensitizing chemicals, haptens. Majority of CHS studies were conducted in mice and there is paucity of data in other experimental animals. In the present study, characteristics of contact hypersensitivity reaction to dinitrochlorobenzene (DNCB) were determined in Th1-prone Dark Agouti (DA) rats by evaluating sensitization phase as a function of time-dependent changes in draining lymph nodes (DLN). Apart from basic indices of DLN activity (cellularity and proliferation), the production of cytokines relevant for CHS induction, interleukin-6 (IL-6), interferon-γ (IFN-γ), interleukin-17 (IL-17) and interleukin-4 (IL-4) was analyzed. Anti-inflammatory cytokine interleukin-10 (IL-10) production by DLN cells was determined as well. Highest production of IL-6, IFN-γ and IL-17 in sensitized animals was observed at day 3 after DNCB application, with a decrease at day 5. Increased messages for IFN-γ and IL-17 were noted at this time point. In contrast to inflammatory cytokines, anti-inflammatory cytokine interleukin-4 (IL-4) was undetectable during the entire sensitization phase. Differential pattern (IL-6 and IFN-γ) and level (IFN-γ and IL-17) of inflammatory cytokine production was noted in sensitized Th2-prone Albino Oxford (AO) rats. Similarly to DA rats, no changes in IL-4 were noted in AO rats. Strain-dependent differences in inflammatory cytokine production seem to be based on anti-inflammatory cytokine interleukin-10 (IL-10). Production of IFN-γ concomitantly with undetectable IL-4 in both strains classify rat CHS to DNCB as Th1/type 1 reaction. Detection of IL-17 in sensitized DLN cells points to the involvement of T(IL-17) cells in rat contact hypersensitivity.

Percutaneous penetration characteristics and release kinetics of contact allergens encapsulated in ethosomes.

BACKGROUND: Formulation of the contact allergens dinitrochlorobenzene and isoeugenol in ethanolic liposomes (ethosomes) increases their sensitizing properties in the local lymph node assay compared with an ethanol-water formulation of the allergens. Likewise, isoeugenol and methyldibromo-glutaronitrile formulated in ethosomes enhanced the patch test reactions in sensitized human volunteers. The relationship between the percutaneous penetration/absorption and sensitization/elicitation phases of contact allergy is not well elucidated. OBJECTIVE: The aim of this study was to investigate whether the observed increased sensitizing and elicitation properties following the formulation of selected contact allergens in ethosomes could be explained by a change in release kinetics of the allergens and their pattern of percutaneous penetration and absorption as well as allergen deposition in epidermis and dermis. METHODS: Release kinetics were studied using dialysis bags, and samples were taken at selected time points until equilibrium was reached. Percutaneous absorption and penetration were studied using human skin on Franz cells, and receptor fluid samples were taken at selected time points. Experiments were terminated after 24 hours, and deposition of allergen in epidermis and dermis was measured. Maximum flux and lag time were calculated. RESULTS: Ethosome formulation decreased the release of both allergens compared with the ethanol-water formulation. Ethosome formulation of dinitrochlorobenzene increased its percutaneous penetration but reduced the percutaneous penetration of isoeugenol compared with control formulations. Likewise, all other calculated parameters showed an opposite trend for the 2 allergens in ethosomes and ethanol-water. CONCLUSIONS: The present study demonstrates that identical ethosomes affect the percutaneous penetration characteristics of 2 allergens differently. Thus, our results indicate that each combination of an allergen and a vehicle needs to be evaluated separately. The exact mechanistic relationship between percutaneous penetration, release kinetics, and allergenicity of chemicals in various vehicles remains to be clarified.

Urocanic acid suppresses induction of immunity in human skin.

BACKGROUND/PURPOSE: Trans-urocanic acid is isomerized to cis-urocanic acid (C-UCA) by ultraviolet radiation. C-UCA suppresses immunity in vitro and in vivo in animals; its effect on human skin is unknown. We sought to determine whether its topical application to normal skin suppresses induction of immunity to dinitrochlorobenzene (DNCB). METHODS: Forty subjects applied C-UCA (0%, 0.02%, 0.2%, or 2%) for 17 days. A 40-mcg dose of DNCB was then applied to induce immunity. Subjects were challenged for immunity at 6-week follow-up by occluding doses of DNCB (0, 3.125, 6.25, or 12.5 mcg) on untreated normal skin. Induced immunity was measured by area of erythema and induration 2 and 4 days postchallenge. RESULTS: No significant differences were found in incidence of sensitization by C-UCA concentration (P=.59). DNCB sensitization developed in all 10 subjects induced through 0% C-UCA (placebo); only 23 of 30 patients were sensitized through skin treated with C-UCA. Mean areas of erythema and induration induced through C-UCA-treated skin were less than those in controls (P < 0.05). The number of Langerhans cells in C-UCA-treated skin was unaffected. Laboratory tests of immune function and lymphocyte numbers were unchanged. CONCLUSION: Topically applied C-UCA blunts normal induction responses to a cutaneous sensitizer.

Ethosome formulations of known contact allergens can increase their sensitizing capacity.

Vesicular systems, such as liposomes and ethosomes, are used in cosmetic and pharmaceutical products to encapsulate ingredients, to protect ingredients from degradation, to increase bioavailability, and to improve cosmetic performance. Some reports have suggested that formulation of cosmetic ingredients in vesicular carrier systems may increase their contact allergy elicitation potential in humans. However, no sensitization studies have been published. We formulated two model contact allergens (isoeugenol and dinitrochlorobenzene) in ethosomes and investigated the sensitization response using a modified local lymph node assay (LLNA). The results were compared with those for the same allergens in similar concentrations and vehicles without ethosomes. Both allergens encapsulated in 200-300 nm ethosomes showed increased sensitizing potency in the murine assay compared with the allergens in solution without ethosomes. Empty ethosomes were non-sensitizing according to LLNA. The clinical implications are so far uncertain, but increased allergenicity from ethosome-encapsulated topical product ingredients cannot be excluded.

Modulated function of tissue efflux transporters under hyperbilirubinemia in rats.

The effect of hyperbilirubinemia on the function of tissue efflux transporters such as multidrug resistance-associated proteins (Mrps) and organic anion transporting polypeptides (Oatps) was examined by measuring tissue accumulation of 2,4-dinitrophenyl-S-glutathione (DNP-SG) after intravenous administration of 1-chloro-2,4-dinitrobenzene (CDNB), a precursor of DNP-SG, in rats. DNP-SG is known as a substrate of both Mrps and Oatps. Hyperbilirubinemia was induced by a bolus intravenous administration of bilirubin. Treatment with probenecid, an inhibitor for both Mrps and Oatps, significantly increased DNP-SG concentrations in the brain, heart, liver, kidney, jejunum, spleen and skeletal muscle as compared with those in control rats, suggesting the expression of some probenecid-sensitive efflux transporters in these tissues. Rats with more than 70 microM of unconjugated/conjugated bilirubin in plasma exhibited significantly higher DNP-SG concentrations in the brain, liver, jejunum, and skeletal muscle. These results suggested that probenecid-sensitive efflux transporters in tissues were suppressed functionally under hyperbilirubinemia. In conclusion, hyperbilirubinemia accompanied by obstructive jaundice is caused by various disease states, which may increase harmful toxicities of exogenously administered Mrps and/or Oatps substrate drugs at various tissues, by suppressing the efflux transporter's function systemically.

Allergic inflammation in the upper respiratory tract of the rat upon repeated inhalation exposure to the contact allergen dinitrochlorobenzene (DNCB).

Previously, the contact allergen dinitrochlorobenzene (DNCB) was identified as a sensitizer by inhalation in BALB/c mice; in addition, DNCB induced a lymphocytic infiltrate in the larynx of dermally sensitized Th1-prone Wistar rats upon a single inhalation challenge. In the present study, repeated inhalation exposures to DNCB were investigated using the same protocol as the single-challenge study: female Wistar rats were dermally sensitized with DNCB and subsequently challenged by inhalation exposure to 7 or 15 mg/m(3) DNCB twice a week for 4 weeks. Allergy-related apnoeic breathing was not observed. DNCB-specific IgG antibodies were found in the serum and--predominantly lymphocytic--inflammations were found in the nasal tissues and larynx. Similar effects were observed in animals repeatedly exposed by inhalation without previous dermal contact, indicating sensitization by inhalation. The inflammation may be the upper respiratory tract analogue of hypersensitivity pneumonitis/allergic alveolitis. Possible progression of the airway inflammation upon long-term exposure should be investigated to support or dismiss discrimination between contact and respiratory allergens in relation to respiratory allergy.