Keratinocyte Proline-Rich Protein Deficiency in Atopic Dermatitis Leads to Barrier Disruption.

Atopic dermatitis is a common inflammatory skin disease caused by the interaction of genetic and environmental factors. By allelic copy number analysis at missense single-nucleotide polymorphisms on 26 genes with copy number variation, we identified a significant association between atopic dermatitis and human KPRP. Human KPRP expression, which was localized to the upper granular layer of epidermis, was significantly decreased in atopic dermatitis compared with normal skin. KPRP was histologically colocalized with loricrin and was mainly detected in cytoskeleton fractions of human keratinocytes. To further investigate the role of KPRP in skin, Kprp-knockout mice were generated. Heterozygous knockout (Kprp+/-) mice exhibited reduced KPRP expression to level a similar to that of human AD lesional skin. Kprp+/- mice showed abnormal desmosome structure and detachment of lower layers of the stratum corneum. Percutaneous inflammation by topical application of croton oil or oxazolone was enhanced, and epicutaneous immunization with ovalbumin induced a high level of IgE in Kprp+/- mice. Our study, started from allelic copy number analysis in human AD, identified the importance of KPRP, the decrease of which leads to barrier dysfunction.

Cutting Edge: Nqo1 Regulates Irritant Contact Hypersensitivity against Croton Oil through Maintenance of Dendritic Epidermal T Cells.

Irritant contact dermatitis (ICD) is associated with local release of inflammatory mediators such as reactive oxygen species and regulated by various antioxidative enzymes and antioxidants. Although Nqo1 is involved in antioxidative reactions and detoxification, its role in ICD remains unknown. Nqo1-deficient mice exhibited augmented ear swelling accompanied by neutrophil infiltration in the croton oil-induced mouse ICD model. In the skin of Nqo1-deficient mice, Vγ5Vδ1+ dendritic epidermal T cells (DETCs), which are known to suppress ICD, were severely reduced. As the transfer of DETCs into Nqo1-deficient mice reversed an increased ICD response, loss of DETCs could account for the increased ICD. DETCs from Nqo1-deficient mice were sensitive to oxidative stress-induced cell death in vitro, and antioxidant NAC treatment in the ears of these mice rescued the number of DETCs and produced a normal ICD response. Taken together, the current results demonstrate that antioxidative enzyme Nqo1 regulates ICD through DETC maintenance.

Exercise Intensity and Duration Effects on In Vivo Immunity.

PURPOSE: To examine the effects of intensity and duration of exercise stress on induction of in vivo immunity in humans using experimental contact hypersensitivity (CHS) with the novel antigen diphenylcyclopropenone (DPCP). METHODS: Sixty-four healthy males completed either 30 min running at 60% V˙O2peak (30MI), 30 min running at 80% V˙O2peak (30HI), 120 min running at 60% V˙O2peak (120MI), or seated rest (CON). Twenty min later, the subjects received a sensitizing dose of DPCP; and 4 wk later, the strength of immune reactivity was quantified by measuring the cutaneous responses to a low dose-series challenge with DPCP on the upper inner arm. Circulating epinephrine, norepinephrine and cortisol were measured before, after, and 1 h after exercise or CON. Next, to understand better whether the decrease in CHS response on 120MI was due to local inflammatory or T-cell-mediated processes, in a crossover design, 11 healthy males performed 120MI and CON, and cutaneous responses to a dose series of the irritant, croton oil (CO), were assessed on the upper inner arm. RESULTS: Immune induction by DPCP was impaired by 120MI (skinfold thickness -67% vs CON; P < 0.05). However, immune induction was unaffected by 30MI and 30HI despite elevated circulating catecholamines (30HI vs pre: P < 0.01) and greater circulating cortisol post 30HI (vs CON; P < 0.01). There was no effect of 120MI on skin irritant responses to CO. CONCLUSIONS: Prolonged moderate-intensity exercise, but not short-lasting high- or short-lasting moderate-intensity exercise, decreases the induction of in vivo immunity. No effect of prolonged moderate-intensity exercise on the skin's response to irritant challenge points toward a suppression of cell-mediated immunity in the observed decrease in CHS. Diphenylcyclopropenone provides an attractive tool to assess the effect of exercise on in vivo immunity.

Modulation of cutaneous inflammation by angiotensin-converting enzyme.

Cutaneous neurogenic inflammation is a complex biological response of the host immune system to noxious stimuli. Present evidence suggests that zinc metalloproteases may play an important role in the regulation of neurogenic inflammation by controlling the local availability of neuropeptides, such as substance P (SP), that are capable of initiating or amplifying cutaneous inflammation after release from sensory nerves. To address the hypothesis that the dipeptidyl carboxypeptidase angiotensin-converting enzyme (ACE) is capable of modulating skin inflammation, we have analyzed murine allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD) using wild-type C57BL/6J (ACE(+/+)) or genetically engineered mice with a heterozygous deletion of somatic ACE (ACE(+/-)). In 2,4-dinitro-1-fluorobenzene-sensitized ACE(+/-) mice, ACD was significantly augmented in comparison to ACE(+/+) controls as determined by the degree of ear swelling after exposure to hapten. Likewise, systemic treatment of ACE(+/+) mice with the ACE inhibitor captopril before sensitization or elicitation of ACD significantly augmented the ACD response. In contrast, local damage and neuropeptide depletion of sensory nerves following capsaicin, injection of a bradykinin B(2), or a SP receptor antagonist before sensitization significantly inhibited the augmented effector phase of ACD in mice with functionally absent ACE. However, in contrast to ACD, the response to the irritant croton oil was not significantly altered in ACE(+/-) compared with ACE(+/+) mice. Thus, ACE by degrading bradykinin and SP significantly controls cutaneous inflammatory responses to allergens but not to irritants, which may explain the frequently observed exacerbation of inflammatory skin disease in patients under medication with ACE inhibitors.

Enhancement of the contact hypersensitivity reaction by acute morphine administration at the elicitation phase.

The present study investigated the effects of morphine on the irritant contact sensitivity (ICS) and contact hypersensitivity (CHS) reaction. ICS was induced by croton oil application on the pinnae of naïve rats. Morphine injected prior to croton oil application did not affect the ICS response when assessed by measurements of pinnae thickness. CHS was induced by applying the antigen 2,4-dinitro-1-fluorobenzene (DNFB) to the pinnae of rats sensitized to DNFB. Rats received an injection of morphine prior to either initial antigen exposure (sensitization) or antigen reexposure (challenge). Morphine prior to challenge, but not sensitization, resulted in a pronounced enhancement of the CHS response as measured by pinna thickness. Quantitative PCR also showed increased IFN-gamma mRNA levels in the inflamed tissue of morphine-treated rats. Naltrexone blocked the morphine-induced enhancement of the CHS response. The differential effects of morphine suggest that opioids have a more pronounced effect on in vivo immune responses that involve immunological memory.

Topical vitamin D3 downregulates IgE-mediated murine biphasic cutaneous reactions.

Hapten-specific and mast-cell-dependent biphasic (immediate and delayed-onset) cutaneous reactions were induced in a murine model by intravenous injection of anti-DNP IgE antibodies followed by a skin test. Four daily applications of topical 1 alpha,24(OH)2D3 ointment significantly inhibited both the immediate and the delayed-onset cutaneous reactions in a dose-dependent fashion, as well as the croton-oil-induced cutaneous reaction and DNFB contact sensitivity reaction. 1 alpha,24(OH)2D3 itself did not show any sensitizing or irritant potential. The inhibitory effect of 1 alpha,24(OH)2D3 on these reactions was limited to the application site and no systemic effect was observed. Another vitamin D3 analog 1 alpha,25(OH)2D3, also showed an inhibitory effect on IgE-mediated cutaneous reactions. These results suggest that topically applied 1 alpha,24(OH)2D3 might modulate IgE-mediated cutaneous reactions and could thus be useful in the treatment of certain human cutaneous disorders other than psoriasis and related keratinizing disorders.

Topical application of cyclosporine on guinea pig allergic contact dermatitis.

Topical cyclosporine applied to the test site substantially inhibited the elicitation reaction of contact sensitivity in the guinea pigs previously sensitized with 2,4-dinitrochlorobenzene (DNCB). This suppressive effect of the drug was short lived and reversible. Cyclosporine was not effective when given six hours or later after antigenic challenge to the test site. Cyclosporine had no effect on the toxic contact reaction in normal animals either to croton oil or to DNCB in high concentration. Cyclosporine applied topically to the challenge site also resulted in a reduction of retest and flare-up reactions of contact sensitivity to DNCB, but did not affect the production of generalized rash in the same animals. These results indicate that in the future local topical application of cyclosporine may make treatment of human cutaneous immune-mediated disorders a possibility without serious side effects.

The effect of selected immunomodulating agents on experimental contact reactions.

A guinea pig experimental model which allows comparison of the macroscopic appearance of skin tests with the nature and degree of the dermal inflammatory cell infiltrate has been used to study the effects of cyclophosphamide, methotrexate, azathioprine and cyclosporin A on contact reactions. The immunomodulating capabilities of the agents tested are assessed by their effects on the allergic contact reaction to oxazolone, a cell-mediated delayed hypersensitivity reaction. Non-specific, anti-inflammatory actions are assessed by effects on the toxic contact reaction to croton oil. Changes are compared to findings in reference animals for each reaction. The reference materials and the uses and limitations of the experimental model are evaluated. When administered prior to sensitization, all agents enhanced the macroscopic appearance of the allergic contact reactions. Changes in the dermal cellular infiltrates were not pronounced. When administered prior to testing, cyclophosphamide, methotrexate and azathioprine caused changes compared to controls which varied in direction and degree both macroscopically and microscopically. Cyclophosphamide which was the most active agent showed non-specific, anti-inflammatory effects and caused a peripheral blood leukopenia, the level and character of which was essentially independent of the dermal cellular infiltrate of tests. Cyclosporin A demonstrated no non-specific, anti-inflammatory activity on the toxic reaction, but had by far the most pronounced immunosuppressant effect of the agents tested, with virtual quenching of both the macroscopic appearance and all aspects of the dermal cellular infiltrates of the allergic contact reaction.

Depression or enhancement of skin reactivity by inflammatory processes in the guinea pig.

An animal model for the excited skin syndrome was developed in the guinea pig. Hyperirritability of the skin could be induced by immunization with Freund's complete adjuvant (FCA). This hyperirritability was evident from the enhancement of both patch test reactions to an irritant (sodium lauryl sulfate) and open epicutaneous test reactions to a contact sensitizer (2,4-dinitrochlorobenzene). The skin tests were performed at sites other than those pretreated with FCA. Maximum enhancement was observed in a period 3-5 weeks after FCA immunization. A similar but less marked hyperirritability could be induced by eliciting a localized chronic croton oil dermatitis. The period of hyperirritability induced by FCA or croton oil was preceded by a short period (1-14 days) of depressed skin reactivity.

Colonic basophil hypersensitivity.

Contact hypersensitivity reactions were elicited by intraluminal application of DNCB to the colon of guinea pigs and were found sometimes to contain large infiltrates of basophils. These colonic basophil hypersensitivity reactions were accompanied by systemic sensitization and were not seen in nonspecific colonic inflammatory responses induced by croton oil. The heterogenous immune inflammatory responses induced in the colon by DNCB contact sensitivity may serve as a model for the study of inflammatory bowel disease.

The long-term effect of radiotherapy on the immune status of patients cured of a gynecologic malignancy.

The long-term effect of radiotherapy on the immune system were evaluated in 52 patients cured for a gynecologic malignancy from 3 to 15 years. Eighty-seven percent of the patients had no depression in cell-mediated immunity as determined by delayed hypersensitivity reaction to DNCB. The absolute lymphocyte count, as well as the circulating immunoglobulins (IgA, IgG, IgM), were within the normal range. Thus, there were no significant changes in cell-mediated immunity and circulating immunoglobulins several years after radical wide-field radiotherapy.

Skin testing for prognosis or therapy formulation in cancer patients: caveat emptor.

Delayed cutaneous hypersensitivity to DNCB was assessed in 56 patients who had epidermoid intraoral carcinoma, prior to therapy. They were followed for 44 months, and their skin reactivity correlated well with both a small tumor size and a favorable clinical prognosis. In a significant number of cases, however, lack of reactivity did not indicate a fatal outcome. Therefore, we recommend caution in the use of any skin test data in formulating therapy. When cured cancer patients were skin-tested, there was no correlation between the state of the disease and their skin reactivity.

Initiation-promotion skin carcinogenesis and immunological competence.

The immune competence of mice during initiation-promotion skin carcinogenesis was determined by skin allograft rejection and lymphocyte mitogenesis. The carcinogen 7, 12-dimethylbenzanthracene inhibited the cellular immune competence of mice while lymphocytes from croton oil treated mice had enhanced PWM response. Chlorphenesin, a stimulator of cellular immunity, was found to inhibit tumorigenesis in initiation-promotion skin carcinogenesis when injected during promotion.

The effect of radial radiotherapy on delayed hypersensitivity and the inflammatory response.

Delayed hypersensitivity to DNCB and the inflammatory response to croton oil wereevaluated in 144 and 121 patients respectively, prior ro and 3 to 6 months following curative radiotherapy. Eighty-one patients had in vitri lymphocyte transformation by PHA;59 (41%) were nonreactors to DNCB and 27 (22%) to croton oil; 29 of 59 (49%) initiallyreactive became anergic. Similiar improvement of the inflammatory response was obtained. Patients who became DNCB-reactive following radiotherapy had the same favorable prognosis as those who were initially reactive. Radiotherapy did not adversely affect either delayed hypersensitivity or the inflammatory response. There was a 50% decrease in PHA stimulation and lymphocyte count after treatment. No correlation was found between DNCB reactivity and lymphocyte transfermation prior to or following radiotherapy. The evaluation of the effect of radiotherapy on cell-mediated immunity depends on the tests used.

Subcellular fractions from dermis and epidermis in contact sensitization of guinea pigs to 1-chloro-2,4-dinitrobenzene.

Subcellular fractions were prepared from the epidermis of guinea pigs which had been painted with 1-chloro-2,4 dinitrobenzene 14 h previously. The microsomal fraction showed less activity than other fractions in the MIF test. Similarly, the microsomal fraction from the dermis of skin irritated with croton oil before DNCB painting was relatively inactive. However, the microsomal fractions from the epidermis and more especially from the dermis of skin painted with DNCB while undergoing allergic contact dermatitis from pentadecylcatechol showed significant MIF activities.