Decreased peripheral basophil counts in urticaria and mouse model of oxazolone-induced hypersensitivity, the latter suggesting basopenia reflecting migration to skin

A decrease in the number of basophils in the peripheral blood, or basopenia, has been noted, reflecting the activity of chronic spontaneous urticaria (CSU). Infiltration of basophils into the skin has also been reported, but the mechanism of basopenia in CSU has not been clarified. The phenomenon of basopenia during the active phase of urticaria was confirmed, and basophil numbers increased following symptom improvement in 15 out of 17 patients treated with omalizumab and in 13 of 15 patients treated with antihistamines. Our examination by immunostaining also revealed basophil infiltration of the CSU lesions, as in previous reports, but since most of our patients were already taking oral steroids, it was not considered appropriate to examine the relationship between basophil numbers in tissue and peripheral blood. Then, we used mouse model of contact hypersensitivity with a single application of oxazolone, which is known to stimulate basophil infiltration, and investigated basophil counts in the skin, peripheral blood, and bone marrow. In this model, a decrease in peripheral blood basophil numbers was observed one day after challenge, but not after 2 days, reflecting supplementation from the bone marrow. Indeed, when cultured basophils expressing GFP were transplanted into the peripheral blood, GFP-positive basophil numbers in the peripheral blood remained low even after 2 days of challenge. Despite differences among species and models, these results suggest that one reason for the decrease of basophils in the peripheral blood in CSU may involve migration of circulating basophils into the skin.

Extract from Black Soybean Cultivar A63 Extract Ameliorates Atopic Dermatitis-like Skin Inflammation in an Oxazolone-Induced Murine Model

Black soybean has been used in traditional medicine to treat inflammatory diseases, cancer, and diabetes and as a nutritional source since ancient times. We found that Korean black soybean cultivar A63 has more cyanidin-3-O-glucoside, (C3G), procyanidin B2 (PB2), and epicatechin (EPC) contents than other cultivars and has beneficial effects on cell viability and anti-oxidation. Given the higher concentration of anthocyanidins and their strong anti-oxidant activity, we predicted that A63 extract could relieve inflammatory disease symptoms, including those of atopic dermatitis (AD). Here, we evaluated the anti-AD activity of A63 extract in an oxazolone (OXA)-induced mouse model. A63 extract treatment significantly reduced epidermal thickness and inflammatory cell infiltration, downregulated the expression of AD gene markers, including Interleukin (IL)-4 and IL-5, and restored damaged skin barrier tissues. Furthermore, A63 extract influenced the activation of the signal transducer and activator of transcription (STAT) 3 and STAT6, extracellular regulatory kinase (ERK), and c-Jun N-terminal kinase (JNK) signaling pathways, which play a crucial role in the development of AD. Altogether, our results suggest that A63 can ameliorate AD-like skin inflammation by inhibiting inflammatory cytokine production and STAT3/6 and Mitogen-activated protein kinase (MAPK) signaling and restoring skin barrier function.

Nintedanib ameliorates animal model of dermatitis

Nintedanib, a receptor tyrosine kinase (RTK) inhibitor has been developed as therapeutics for idiopathic pulmonary fibrosis and non-small lung cancer. We found that the expression levels of RTK, especially VEGFR1 is increased in skin biopsies of dermatitis patients from multiple independent datasets. Moreover, VEGFR1 is highly expressed by infiltrated cells in dermis from oxazolone (OXA) treated mice. Interestingly, nintedanib alleviates dermatitis symptom in OXA-induced animal model. Especially, levels of epidermis thickness, infiltrated immune cells including mast cells and eosinophils were decreased from mice cotreated with nintedanib and OXA compared with OXA treated mice. Moreover, serum IgE and Th2 cytokines including IL-4 and IL-13 were decreased by nintedanib treatment. These results suggest an evidence that nintedanib alleviates animal model of dermatitis.

The regulatory B cell-mediated peripheral tolerance maintained by mast cell IL-5 suppresses oxazolone-induced contact hypersensitivity

The function of regulatory immune cells in peripheral tissues is crucial to the onset and severity of various diseases. Interleukin-10 (IL-10)-producing regulatory B (IL-10⁺ B_reg) cells are known to suppress various inflammatory diseases. However, evidence for the mechanism by which IL-10⁺ B_reg cells are generated and maintained is still very limited. Here, we found that IL-10⁺ B_reg cells suppress the activation of IL-13-producing type 2 innate lymphoid cells (IL-13⁺ ILC2s) in an IL-10-dependent manner in mice with oxazolone-induced severe contact hypersensitivity (CHS). Mast cell (MC) IL-5 was important for maintaining the population of IL-10⁺ B_reg cells in peripheral lymphoid tissues. Overall, these results uncover a previously unknown mechanism of MCs as a type of immunoregulatory cell and elucidate the cross-talk among MCs, IL-10⁺ B_reg cells, and IL-13⁺ ILC2s in CHS.

Anti-Inflammatory Activities of Pentaherbs Formula, Berberine, Gallic Acid and Chlorogenic Acid in Atopic Dermatitis-Like Skin Inflammation

Atopic dermatitis (AD) is a common allergic skin disease, characterized by dryness, itchiness, thickening and inflammation of the skin. Infiltration of eosinophils into the dermal layer and presence of edema are typical characteristics in the skin biopsy of AD patients. Previous in vitro and clinical studies showed that the Pentaherbs formula (PHF) consisting of five traditional Chinese herbal medicines, Flos Lonicerae, Herba Menthae, Cortex Phellodendri, Cortex Moutan and Rhizoma Atractylodis at w/w ratio of 2:1:2:2:2 exhibited therapeutic potential in treating AD. In this study, an in vivo murine model with oxazolone (OXA)-mediated dermatitis was used to elucidate the efficacy of PHF. Active ingredients of PHF water extract were also identified and quantified, and their in vitro anti-inflammatory activities on pruritogenic cytokine IL-31- and alarmin IL-33-activated human eosinophils and dermal fibroblasts were evaluated. Ear swelling, epidermis thickening and eosinophils infiltration in epidermal and dermal layers, and the release of serum IL-12 of the murine OXA-mediated dermatitis were significantly reduced upon oral or topical treatment with PHF (all p < 0.05). Gallic acid, chlorogenic acid and berberine contents (w/w) in PHF were found to be 0.479%, 1.201% and 0.022%, respectively. Gallic acid and chlorogenic acid could suppress the release of pro-inflammatory cytokine IL-6 and chemokine CCL7 and CXCL8, respectively, in IL-31- and IL-33-treated eosinophils-dermal fibroblasts co-culture; while berberine could suppress the release of IL-6, CXCL8, CCL2 and CCL7 in the eosinophil culture and eosinophils-dermal fibroblasts co-culture (all p < 0.05). These findings suggest that PHF can ameliorate allergic inflammation and attenuate the activation of eosinophils.

Oxazolone-induced contact hypersensitivity reduces lymphatic drainage but enhances the induction of adaptive immunity

Contact hypersensitivity (CHS) induced by topical application of haptens is a commonly used model to study dermal inflammatory responses in mice. Several recent studies have indicated that CHS-induced skin inflammation triggers lymphangiogenesis but may negatively impact the immune-function of lymphatic vessels, namely fluid drainage and dendritic cell (DC) migration to draining lymph nodes (dLNs). On the other hand, haptens have been shown to exert immune-stimulatory activity by inducing DC maturation. In this study we investigated how the presence of pre-established CHS-induced skin inflammation affects the induction of adaptive immunity in dLNs. Using a mouse model of oxazolone-induced skin inflammation we observed that lymphatic drainage was reduced and DC migration from skin to dLNs was partially compromised. At the same time, a significantly stronger adaptive immune response towards ovalbumin (OVA) was induced when immunization had occurred in CHS-inflamed skin as compared to uninflamed control skin. In fact, immunization with sterile OVA in CHS-inflamed skin evoked a delayed-type hypersensitivity (DTH) response comparable to the one induced by conventional immunization with OVA and adjuvant in uninflamed skin. Striking phenotypic and functional differences were observed when comparing DCs from LNs draining uninflamed or CHS-inflamed skin. DCs from LNs draining CHS-inflamed skin expressed higher levels of co-stimulatory molecules and MHC molecules, produced higher levels of the interleukin-12/23 p40 subunit (IL-12/23-p40) and more potently induced T cell activation in vitro. Immunization experiments revealed that blockade of IL-12/23-p40 during the priming phase partially reverted the CHS-induced enhancement of the adaptive immune response. Collectively, our findings indicate that CHS-induced skin inflammation generates an overall immune-stimulatory milieu, which outweighs the potentially suppressive effect of reduced lymphatic vessel function.

Intranasally administered antigen 85B gene vaccine in non-replicating human Parainfluenza type 2 virus vector ameliorates mouse atopic dermatitis

Atopic dermatitis (AD) is a refractory and recurrent inflammatory skin disease. Various factors including heredity, environmental agent, innate and acquired immunity, and skin barrier function participate in the pathogenesis of AD. T -helper (Th) 2-dominant immunological milieu has been suggested in the acute phase of AD. Antigen 85B (Ag85B) is a 30-kDa secretory protein well conserved in Mycobacterium species. Ag85B has strong Th1-type cytokine inducing activity, and is expected to ameliorate Th2 condition in allergic disease. To perform Ag85B function in vivo, effective and less invasive vaccination method is required. Recently, we have established a novel functional virus vector; recombinant human parainfluenza type 2 virus vector (rhPIV2): highly expressive, replication-deficient, and very low-pathogenic vector. In this study, we investigated the efficacy of rhPIV2 engineered to express Ag85B (rhPIV2/Ag85B) in a mouse AD model induced by repeated oxazolone (OX) challenge. Ear swelling, dermal cell infiltrations and serum IgE level were significantly suppressed in the rhPIV2/Ag85B treated mouse group accompanied with elevated IFN-γ and IL-10 mRNA expressions, and suppressed IL-4, TNF-α and MIP-2 mRNA expressions. The treated mice showed no clinical symptom of croup or systemic adverse reactions. The respiratory tract epithelium captured rhPIV2 effectively without remarkable cytotoxic effects. These results suggested that rhPIV2/Ag85B might be a potent therapeutic tool to control allergic disorders.

FTY720 ameliorates oxazolone colitis in mice by directly affecting T helper type 2 functions

The sphingosine-1-phosphate analogue FTY720 is known to alter migration and homing of lymphocytes via sphingosine-1-phosphate receptors. However, several studies indicate that its mode of action is more complex and that FTY720 may also directly influence cytokine effector functions. Therefore, we studied the effect of FTY720 in T helper type (Th2)-mediated oxazolone-induced colitis in mice. Following rectal oxazolone instillation, Th2 cells producing IL-13 induce a progressive colitis resembling human ulcerative colitis. A rectal enema of oxazolone [90 mg/kg body weight] was applied to BALB/c mice. FTY720 was administered i.p. from day 0 to 3 or from day 3 to 5 following the instillation of the haptenating agent. Assessment of severity of colitis was performed daily. FTY720 plasma levels were detected using LC-MS/MS-analysis. Colon tissue was analyzed macroscopically and microscopically, myeloperoxidase activity as well as cytokine levels of lamina propria CD4(+) T-cells and T1/ST2 expression were determined. Treatment with FTY720 prominently reduced the clinical and histopathologic severity of oxazolone-induced colitis, abrogating body weight loss, diarrhea, and macroscopic and microscopic intestinal inflammation. The therapeutic effects of FTY720 were associated with a prominent reduction of the key effector Th2 cytokines IL-13, IL-4 and IL-5. Strikingly, FTY720 inhibited GATA3 and T1/ST2 expression which represent highly relevant markers for Th2 differentiation and Th2 effector function, respectively. Our data provide the first evidence that FTY720 exhibits beneficial prophylactic as well as therapeutic effects in Th2-mediated experimental colitis by directly affecting Th2 cytokine profiles probably by reducing T1/ST2, thus offering a new auspicious therapeutic instrument for the treatment of human ulcerative colitis.

Oxazolone-induced murine model of ulcerative colitis

OBJECTIVE

Animal models are useful for studying disease, but there is a shortage of suitable models of ulcerative colitis. The aim of the present study was to set up an oxazolone-induced murine colitis model and use it to research the pathogenesis of inflammatory bowel disease.

METHODS

BALB/c mice were presensitized by painting the skin with 0.2 mL 3% oxazolone in 100% ethanol on days 0 and 1 followed by intrarectal administration of 0.15 mL 1% oxazolone in 50% ethanol on day 7. The disease activity index (DAI), histological changes of the colon, myeloperoxidase (MPO) activity and production of cytokines (TNF-alpha, IL-4, IFN-gamma) by the mucosa were evaluated.

RESULTS

There were obvious changes in the DAI, histology and MPO activity, and the production of interleukin-4 was markedly increased compared with the concentrations of TNF-alpha and IFN-gamma, which remained normal, in the lesions.

CONCLUSION

Oxazolone colitis is Th2-mediated and has similar histologic features and distribution of inflammation to ulcerative colitis (UC), which has important implications for the use of this model in the study of the pathogenesis and treatment of UC.

Anti-allergic activity of 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide

Glycyrrhizin (18beta-glycyrrhetinic acid-3-O-beta-D-glucuronopyranosyl-(1 --> 2)-beta-D-glucuronide, GL) was transformed to 18beta-glycyrrhetinic acid-3-O-beta-D-glucuronide (GAMG) by Streptococcus LJ-22. The antiallergic activities of GL and GAMG was measured using a RBL cell assay system and contact hypersensitivity model mice. GAMG exhibited anti-allergic activity with IC50 values of 0.28 mM. GAMG, which is sweeter than GL, and 18beta-glycyrrhetinic acid, which is a GAMG metabolite by human intestinal bacteria, also inhibited the passive cutaneous anaphylaxis and skin contact inflammation. In conclusion, GAMG may be useful as a new sweet food additive and an anti-allergic agent.

Effect of protease-activated receptor-2 deficiency on allergic dermatitis in the mouse ear

To investigate the involvement of protease-activated receptor-2 (PAR-2) in allergic dermatitis, we generated PAR-2-deficient (PAR-2(-/-)) mice. Ear thickness, contact hypersensitivity (CH) induced by topical application of picryl chloride (PC) or oxazolone (Ox) after sensitization, and vascular permeability after ear passive cutaneous anaphylaxis (PCA) were compared between wild-type (WT) and PAR-2(-/-) mice. Ear thickness was almost the same in untreated WT and PAR-2(-/-) mice. Topical application of PC or Ox thickened the ears at 6, 24 and 48 h after challenge with a peak at 24 h in WT mice. In PAR-2(-/-) mice, the ear swelling induced by both PC and Ox was suppressed at every time point, and significant inhibition was found at 24 h in PC-induced CH and at 24 and 48 h in Ox-induced CH. Histopathological observation of the ears at 24 h after challenge revealed that PC- or Ox-induced ear edema and infiltration of inflammatory cells in WT mice were greatly attenuated in PAR-2(-/-) mice. The vascular permeability in the ears after PCA was not different between WT and PAR-2(-/-) mice. These results strongly suggest that PAR-2 plays a crucial role in type IV allergic dermatitis but not in type I allergic dermatitis.

P-Selectin glycoprotein ligand 1 (PSGL-1) is a physiological ligand for E-selectin in mediating T helper 1 lymphocyte migration

P-selectin glycoprotein ligand 1 (PSGL-1) is a sialomucin expressed on leukocytes that mediates neutrophil rolling on the vascular endothelium. Here, the role of PSGL-1 in mediating lymphocyte migration was studied using mice lacking PSGL-1. In a contact hypersensitivity model, the infiltration of CD4(+) T lymphocytes into the inflamed skin was reduced in PSGL-1-deficient mice. In vitro-generated T helper (Th)1 cells from PSGL-1-deficient mice did not bind to P-selectin and migrated less efficiently into the inflamed skin than wild-type Th1 cells. To assess the role of PSGL-1 in P- or E-selectin-mediated migration of Th1 cells, the cells were injected into E- or P-selectin-deficient mice. PSGL-1-deficient Th1 cells did not migrate into the inflamed skin of E-selectin-deficient mice, indicating that PSGL-1 on Th1 cells is the sole ligand for P-selectin in vivo. In contrast, PSGL-1-deficient Th1 cells migrated into the inflamed skin of P-selectin-deficient mice, although less efficiently than wild-type Th1 cells. This E-selectin-mediated migration of PSGL-1-deficient or wild-type Th1 cells was not altered by injecting a blocking antibody to L-selectin. These data provide evidence that PSGL-1 on Th1 cells functions as one of the E-selectin ligands in vivo.

Inhibition of allergic contact dermatitis to DNCB but not to oxazolone in interleukin-4-deficient mice

The role of interleukin-4 as a regulator of immune responses in the skin is investigated with regard to the outcome of contact hypersensitivity reaction in interleukin-4-deficient BALB/C mice. In previous studies conflicting results were obtained concerning the role of interleukin-4 in contact hypersensitivity reactions supporting either a proinflammatory or rather an inhibitory function of this cytokine. Interleukin-4 deficient BALB/C mice sensitized to 2,4-dinitrochlorobenzene showed after challenge a significant reduction in magnitude and duration of the contact hypersensitivity response in comparison with wild-type mice. This attenuation was accompanied by a significant reduction of edema and cellular infiltrates in the dermis and a lacking induction of IL-10 mRNA expression in skin. Also, adoptive transfer experiments revealed that BALB/C mice failed to exhibit contact hypersensitivity after injection of lymph node cells obtained from sensitized interleukin-4 deficient mice. To examine further the role of the contact allergen used to induce the contact hypersensitivity response, mice were also sensitized and challenged with Oxazolone. Here a similar magnitude and duration of contact hypersensitivity in both the interleukin-4 deficient mice and BALB/C control mice was observed. This indicates that the contact hypersensitivity response to 2,4-dinitrochlorobenzene and Oxazolone may partly evolve on different pathways being dependent and independent of interleukin-4. Our results clearly show that the complete loss of endogenous interleukin-4 expression in BALB/C mice is associated with an impaired manifestation of contact hypersensitivity response to 2,4-dinitrochlorobenzene, implying an important proinflammatory function of this cytokine.

Oxazolone-induced colitis in rats: effects of budesonide, cyclosporin A, and 5-aminosalicylic acid

BACKGROUND

The intention of the present study was to develop a new hapten-based inflammatory bowel disease model in the rat, useful for pharmacologic screening of new substances with anti-inflammatory properties and immunomodulating capacities. It was considered important to avoid the use of an irritating barrier breaker, such as ethanol.

METHODS

Dark Agouti rats were skin-sensitized with oxazolone and further challenged intra-rectally with oxazolone dissolved in carmellose sodium (Orabase)/peanut oil. The effects of treatment with budesonide, prednisolone, cyclosporin A, and 5-aminosalicylic acid (5-ASA) were studied.

RESULTS

The intra-rectal challenge with oxazolone in sensitized rats induced an inflammation with an increased colon wet weight, pronounced myeloperoxidase (MPO) activity, and hyperemia/ulcerations in the epithelial lining. Improvement was achieved by treatment with budesonide, prednisolone, and cyclosporin A but not with 5-ASA.

CONCLUSIONS

The model fulfills the criteria for a fast, reproducible animal model for human colon inflammation, suitable for pharmacologic screening and studies of an immune-driven colon inflammation.

Differential induction of cutaneous TNF-alpha and IL-6 by topically applied chemicals

BACKGROUND

Increasing evidence shows that contact allergens and skin irritants can induce or upregulate the cutaneous expression of cytokines, including those that are required for the initiation of immune responses and which participate in inflammatory reactions.

OBJECTIVE

The present investigation compared the ability of the skin allergens oxazolone and 2,4-dinitrochlorobenzene (DNCB) and the skin irritant benzalkonium chloride (BZC) to stimulate the cutaneous expression of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) in mice.

RESULTS

Each chemical tested induced the dose-dependent production of IL-6 with similar kinetic profiles. BZC was less effective at provoking increases in this cytokine; concentrations (1%) that caused marked edema failed to stimulate significant changes in IL-6 expression. Under conditions of topical exposure in which each of these chemicals caused a vigorous inflammatory response in the skin, as measured by induced edema and the increased production of IL-6, only oxazolone and DNCB stimulated expression of TNF-alpha. The failure of BZC to initiate TNF-alpha production in the skin was not attributable to inhibition of the bioassay used to measure this cytokine and was apparently independent of the stimulation by this chemical of TNF-alpha inhibitory factors.

CONCLUSION

These data indicate that not all chemicals that have the ability to cause skin irritation and cutaneous inflammation will elicit detectable TNF-alpha responses and that characterization of cutaneous irritants and allergens on the basis of induced cytokine expression patterns in the skin must be approached with caution.

Cyclophosphamide and interleukin-12 synergistically upregulate the acquisition of allergic contact dermatitis in the mouse

Cyclophosphamide given before allergen and recombinant interleukin-12 administered at the time of allergic sensitization substantially increase the acquisition of allergic contact dermatitis in the mouse. Since their immunoadjuvant mechanisms appeared different, it seemed probable that combining cyclophosphamide pretreatment with interleukin 12 administration would result in a more intense allergic contact dermatitis than when either agent was used alone. This was tested in different groups of mice sensitized to dinitrofluorobenzene or to oxazolone. Consistently, immunopotentiation of allergic contact dermatitis was significantly greater with the two immunoadjuvants than with either alone. This immunoadjuvant combination is likely to find use in immunization protocols designed to induce a Th-1 helper cell response.

Comparison of sensitizing protocols for ultraviolet B-induced immunosuppression in C3H mice

To compare previously used protocols for ultraviolet (UV)-induced suppression of contact hypersensitivity in mice, and to develop an optimized protocol for C3H mice, the effect of 3 different allergens, varying allergen concentrations in the induction or challenge phase, local and distant sites of allergen application in respect to irradiation site, 2 mouse substrains and 2 different light sources was studied. A concentration of 0.5% of oxazolone (OXA) gave a slightly better contact sensitization than a 1% concentration of trinitrochlorobenzene (TNCB). Titration experiments revealed that for both OXA and TNCB, a 1% sensitization concentration was optimal, while the optimal challenge concentration was 0.5% for OXA and 1% for TNCB. The magnitude of the resulting contact sensitization was not influenced by either the mouse substrain (C3H/HeJ or C3H/HeN) or the site of allergen application (back or belly), but application of fluorescein isothiocyanate to the ears only produced weak sensitization. A standard UVB dose of 1.3 kJ/m2 suppressed TNCB contact sensitivity to a greater extent than that of OXA. A similar degree of UV-induced suppression was obtained with a given UVB dose, irrespective of a 50-fold difference in the concomitant UVA dose. Based on our results, a proper protocol of contact sensitization for UV-induced immunosuppression in C3H mice includes sensitization with 0.5% OXA on either the mouse back or belly, ear challenge with 0.5% OXA and ear swelling reading 24 h after challenge.

Cytokine induction in human epidermal keratinocytes exposed to contact irritants and its relation to chemical-induced inflammation in mouse skin

In response to exogenous stimuli such as phorbol-12-myristate 13-acetate, ultraviolet B radiation, and lipopolysaccharide, human keratinocytes produce soluble mediators that are important in primary contact irritancy including cytokines that are associated with proinflammatory properties (interleukin-1 alpha [IL-1 alpha], tumor necrosis factor alpha), chemotaxis (IL-8), and growth activation (granulocyte/macrophage colony stimulating factor, IL-6, transforming growth factor alpha). We examined qualitative and quantitative changes in selected intracellular and secreted cytokines in human keratinocyte cultures in response to non-sensitizing contact irritants (croton oil, sodium lauryl sulfate, methyl salicylate, ethyl phenylpropiolate), sensitizing irritants (oxazolone, dinitrofluorobenzene), and ulcerative agents (phenol, benzalkonium chloride, chromium trioxide). The chemicals were also applied to mouse skin to assess whether the chemical-specific pattern of inflammation correlated with the in vitro production of keratinocyte-derived cytokines. Although all agents elicited neutrophils to the site of chemical application, time dependent and chemical-specific patterns of inflammation could be detected. Sodium lauryl sulfate, phenol, and croton oil induced increases in IL-8 production at non-cytotoxic concentrations in semi-confluent human keratinocyte cultures. Phenol and croton oil stimulated tumor necrosis factor alpha production, whereas croton oil was the only agent found to induce granulocyte/macrophage colony-stimulating factor production. Croton oil, phenol, benzalkonium chloride, and dinitrofluorobenzene induced the intracellular production of IL-1 alpha without a concomitant release into the medium. The release of cytokines occurred in parallel with a relative increase in cytokine-specific mRNA transcripts. Studies using neutralizing antibodies to tumor necrosis factor alpha and IL-1 alpha demonstrated that IL-8 induction by croton oil and phenol occurred directly rather than through autocrine circuits. These data suggest that a given pattern of cytokine production is chemical-specific and may predict the contribution of keratinocytes to skin inflammation.

Effect of local ultraviolet irradiation on infections of mice with Candida albicans, Mycobacterium bovis BCG, and Schistosoma mansoni

In this study, we investigated whether mice given ultraviolet (UV)-B (280-320 nm) radiation in doses sufficient to alter cutaneous immune cells and impair the induction of contact hypersensitivity would also have impaired resistance to infectious agents administered at the site of UV irradiation. C3H mice were exposed to 400 J/m2 UVR from FS40 sunlamps on four consecutive days. Immediately after the last UV treatment, groups of mice were injected subcutaneously with Candida albicans, injected intradermally (ID) with Mycobacterium bovis bacillus Calmette-Guerin (BCG), or infected percutaneously with Schistosoma mansoni in UV-irradiated skin. The induction of the delayed hypersensitivity response to C. albicans and BCG, as assessed by footpad swelling, was unaffected by UV irradiation. However, the number of viable mycobacteria recovered from the lymphoid organs of BCG-infected mice was increased significantly in the UV-irradiated animals for a period of more than 2 months. Low-dose UV irradiation of the skin at the site of infection did not influence the number of S. mansoni parasites recoverable from the internal organs of mice that had been infected with cercariae percutaneously 6 weeks earlier. We conclude that the ability of UV radiation to impair the development of cell-mediated immunity to antigens introduced in a UV-irradiated site is not universal and depends on the particular antigen administered. We hypothesize that the involvement of epidermal Langerhans cells as the primary antigen-presenting cells in the induction of cell-mediated immunity may be the critical factor in determining whether a particular immune response will be affected by local UV irradiation.

Contact sensitivity in the murine oral mucosa. I. An experimental model of delayed-type hypersensitivity reactions at mucosal surfaces

We have examined in a murine model, the potential of the oral mucosa (OM) to serve as inductive and/or expression site(s) of delayed-type hypersensitivity (DTH) reactions. The expression of DTH reactions in the murine buccal mucosa was studied after topical application of oxazolone or picryl chloride onto the OM of animals previously sensitized with either hapten. Irrespective of the site of priming (skin or buccal mucosa), inflammatory cells appeared in the OM following buccal elicitation with the pertinent hapten. The density of infiltrating cells peaked at 24 h after hapten elicitation. Such inflammatory reactions, which comprised mainly mononuclear cells at 24 h, were preceded by an early inflammatory reaction that developed only in animals previously sensitized at skin sites. This early reaction, comprising mainly PMN neutrophils, peaked at 6-8 h, declined by 8-16 h, and was not observed in mice previously sensitized in the buccal mucosa. The 24 h reactions failed to develop in nude mice similarly treated, in intact unsensitized mice, as well as in animals sensitized with an irrelevant hapten. These reactions could be adoptively transferred to naive animals by LN cells but not by serum from sensitized syngeneic donors. Furthermore, LN cell suspensions depleted of T cells failed to transfer sensitization for subsequent OM DTH. Topical application of contact sensitizing haptens onto OM induced priming for subsequent DTH reactions elicited with recall antigen applied at a distant skin site or at a local buccal site. These results demonstrate that the OM has the capacity to serve both as an inductive and as an expression site for T cell-mediated inflammatory reactions, be these expressed or induced at local mucosal sites or at remote systemic (skin) sites. This animal model should be valuable for studying the regulation of T cell-mediated inflammatory responses at mucosal surfaces.

Value of the cutaneous basophil hypersensitivity (CBH) response for distinguishing weak contact sensitization from irritation reactions in the guinea pig

Numerous studies of the histology of allergic contact dermatitis reactions to potent allergens in guinea pigs and humans have indicated that there is significant tissue infiltration with basophilic leukocytes. In this study we determined whether this histologic finding could be of value in distinguishing weak sensitization reactions from primary irritation, thereby aiding in the predictive identification of weak or moderate contact allergens. Guinea pigs were sensitized by the Buehler test method. Skin reactions were graded 24, 48, and 72 h post-challenge with duplicate patch sites biopsied at the 24- or 72-h grading timepoints. The biopsies were fixed, embedded in glycol methacrylate, thin sectioned, and Giemsa stained. The number of basophils per 400 leukocytes were counted along the upper dermis just below the dermal/epidermal junction. Challenge patch sites from animals sensitized to a relatively low dose of the strong contact allergen, oxazolone, were compared with patch sites from animals challenged only with a strong irritant, sodium lauryl sulfate (SLS). Compared to normal skin (7.5 +/- 1.0 basophils/400 leukocytes +/- SEM) only the oxazolone patch sites showed significant basophil infiltration (36.8 +/- 6.5), despite the fact that the skin reactions to the low oxazolone challenge dose were relatively weak. SLS patch sites showed no basophil infiltration above normal skin levels (4.8 +/- 0.9). Subsequent blinded studies compared weak/moderate presumptive sensitization reactions (as defined by accepted visual skin grading criteria) to various chemicals (citronellal, vanillin, cinnamic aldehyde, and ethylenediamine) to primary irritation reactions to the same chemicals. In each case, low-challenge-dose sensitization sites on previously treated (induced) animals showed mean basophil infiltration (range, 11.9-69.2 basophils/400 leukocytes) significantly greater than higher-dose irritant reactions (range, 1.6-13.3). The range for normal skin was 0.2-10.2 and the range for strong patch reactions to higher concentrations of oxazolone was 59.8-209.3. These data strongly indicate that light-microscopic quantitation of the CBH response can be used to distinguish relatively weak to moderate contact sensitization reactions from primary irritation reactions to the same chemicals.

Effects of rifampin treatment on contact sensitivity reactions to oxazolone in Balb/C mice

Treatment of mice with rifampin (Ri, 100-200 mg/kg) affected the course of contact sensitivity (CS) reactions to oxazolone. The effects which were seen as either partial inhibition or enhancement of the response, under one set of conditions, could be abrogated or even reversed if conditions of either induction, elicitation and time of measuring reactions were altered. In addition, amount of Ri used for treatment and time of treatment in relation to the induction of CS reactions also influenced the effects observed.

Effects of clonidine on the dermal inflammatory cell response of experimental toxic and allergic contact reactions and intradermal hypersensitivity

In previous studies, the alpha 2-adrenoceptor agonist clonidine has been shown to suppress the wheal and flare reaction in guinea pigs sensitized to ovalbumin. This phenomenon has been further studied with special reference to effects on the dermal inflammatory cell infiltrate and mast cells. Clonidine lessens the degranulation of mast cells seen in control untreated immediate hypersensitivity reactions. Less neutrophils and eosinophils arrive to the treated reactions. Basophils and mononuclear cells (chiefly lymphocytes) which characterize the late phase of the wheal and flare reaction were not influenced by clonidine. Clonidine had a possible minimal effect on allergic contact (delayed hypersensitivity) reactions. The toxic contact reaction to croton oil (nonspecific cutaneous inflammation) was not affected.

Effects of dietary copper depletion on acute and delayed inflammatory responses in mice

Acute and delayed hypersensitivity reactions were compared in mice fed diets low in copper (less than 20 mumol copper kg-1) or adequate (more than 300 mumol copper kg-1) for seven to nine weeks after weaning. In the copper depleted animals there was a significant enhancement (P less than 0.01) of histamine-induced paw oedema measured 15 minutes after challenge. The variance of responses within the two dietary groups was similar. Delayed contact hypersensitivity reactions to oxozalone were also significantly increased (P less than 0.01) in the deficient mice. In this study there were some signs of differences in variance heterogeneity but they were statistically insignificant. Delayed-type hypersensitivity to sheep erythrocytes was similarly but less markedly (P less than 0.05) affected. Group differences just failed to reach statistical significance after logarithmic transformation (P less than 0.07) or non-parametric analysis (P less than 0.06). At challenge, the copper deficient mice had a significant (P less than 0.05) plasma hypercholesterolaemia. A few individuals also showed signs of spleen enlargement and mild haemoglobinaemia but otherwise the animals appeared clinically normal and were similar in weight to the controls. Plasma (P less than 0.001), erythrocyte (P less than 0.01) and liver (P less than 0.01) copper concentrations were significantly reduced in the copper-depressed mice, although the concentrations of copper and zinc in the spleen were increased (P less than 0.05) in the same group. Whole blood superoxide dismutase activity was also significantly decreased (P less than 0.01) but erythrocyte glutathione peroxidase activities were similar in both groups, as were blood and liver zinc concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Contact sensitivity in the guinea pig eye

Guinea pigs were sensitized systemically with the contact sensitizer oxazolone and challenged by topical application of the chemical to the eye and the skin. Inflammatory reactions of the conjunctiva, cornea and skin were uniformly elicited, but these were most intense clinically following intradermal sensitization with mycobacterial adjuvants. Mononuclear, neutrophilic and eosinophilic leukocytes infiltrated the ocular tissues and skin 24 hours after challenge. Basophils, which were prominent in the cutaneous reactions, were virtually absent from ocular tissues.

Reduction of contact sensitivity reactions to oxazolone in mite-infested mice

Oxazolone-sensitized mite-infested (SWR-M) and mite-free (SWR-J) mice were challenged with oxazolone on the skin of the neck and shoulder. The migration of radioactively labeled cells to the site of contact sensitivity reaction to oxazolone was significantly less in SWR-M than in SWR-J mice. Serum obtained from SWR-M mice suppressed the extravasation of cells into the skin site of SWR-J mice challenged with oxazolone. The decrease in cellular influx in SWR-M mice occurred in areas of mite infestation (skin of neck and shoulder) as well as in areas not infested with mites (the ears). SWR-M mice also gave evidence of enhanced vascular permeability. A possible role for histamine in the inhibition of contact sensitivity in mite-infested mice is discussed.

Depression of contact sensitivity by Pseudomonas aeruginosa-induced suppressor cells which affect the induction phase of immune response

The cellular basis of depression of contact sensitivity to oxazolone in mice injected with Pseudomonas aeruginosa was studied. Cells from draining lymph nodes of mice sensitized with oxazolone 18 h previously were able to induce contact sensitivity to normal mice when administered in their footpads. In contrast, cells from draining lymph nodes of P. aeruginosa-injected and oxazolone-sensitized donors failed to induce contact sensitivity when injected in the footpad of normal mice and were capable of actively blocking the immunizing process brought about by lymph node cells from sensitized mice when injected together in the footpad of normal recipients. The P. aeruginosa-induced suppressor cells required antigenic stimulation, had precursors sensitive to cyclophosphamide, and did not affect the effector mechanisms of contact sensitivity. Thus, the results suggest that P. aeurginosa depresses contact sensitivity to oxazolone by enhancing the activity of suppressor cells which normally arise during the sensitization process and which affect the afferent limb of the immune response, probably by inhibiting the normal recruitment of T lymphocytes in the draining lymph nodes.

Contact sensitivity in alloxan-diabetic mice

Alloxan-diabetic mice of Swiss, CBA and DBA/2 strains show a significant depression of contact sensitivity to oxazolone, as compared with normoglycaemic control animals, which is accompanied by the involution of the thymus and spleen. Insulin treatment partially restores the contact sensitivity in diabetic animals and also increases the weight of lymphatic organs. In contrast, the non-specific inflammatory response to oxazolone is not impaired in insulin-deficient mice. Further experiments have shown that neither sensitized lymphocytes of control animals given to diabetic mice, nor sensitized lymphocytes of diabetic mice injected into normoglycaemic recipients, were able to transfer passively any significant contact sensitivity. It is suggested that in alloxan-diabetic mice the function of T lymphocytes is affected.