Polypodium leucotomos inhibits ultraviolet B radiation-induced immunosuppression.

BACKGROUND: An extract of the tropical fern Polypodium leucotomos (PL) administered orally to mice inhibits ultraviolet B (UVB) radiation-induced skin cancer formation. UVB-induced murine skin cancers occur, in part, because of UVB-induced immunosuppression. Thus, we examined whether PL inhibits UVB-suppression of the induction of contact hypersensitivity (CHS) locally or systemically. METHODS: C57BL/6 mice received standard drinking water or water-containing PL. In the local model, mice were shaved on the dorsum and exposed to 3500 J/m(2) of UVB radiation daily for 4 days. Control mice were not irradiated. After the last irradiation they were sensitized to oxazolone topically at the irradiated site. To examine the ability of PL to inhibit systemic UVB-induced immunosuppression, mice were given 10,000 J/m(2) of UVB radiation once and immunized at a non-exposed site 3 days later. Six days after immunization (in both models), mice were challenged on the ears with oxazolone and 24/48 h ear swelling assessed. RESULTS: PL in drinking water significantly reduced the inhibition of CHS observed with exposure to UVB radiation in both the local and systemic models. CONCLUSIONS: The ability of PL to inhibit UVB radiation-induced immune suppression may explain, in part, its ability to inhibit UVR-induced skin cancer induction in mice.

Mystery of the disappearing allergen: published allergens rarely seen again.

Patch testing is an important tool in the diagnosis of allergic contact dermatitis. Although this technique can be accurate, occasionally the results may be inconclusive. A previously positive result to an allergen may become negative upon repeat testing, and this may complicate the process of achieving a definitive diagnosis. There are some potential explanations for such inconsistencies, including the Excited Skin Syndrome, irritant reactions, a need to repeat the diagnostic algorithm, "rogue" reactions, and "contact allergy." These explanations should be taken into account when interpreting these results. However, further knowledge is needed to solve the mystery of an allergen that subsequently disappears.

Avoiding paraphenylenediamine exposure in children.

Although the allergenic potential of PPD is well known, it was chosen by the American Contact Dermatitis Society as the 2006 "allergen of the year" in order to increase awareness of new patterns of exposure and increasing sensitization. Temporary tattoos are a vehicle of contact with PPD that is particularly relevant to children. They are a risk not only in the United States, but in many international locations frequented by American tourist families. Adolescents dyeing their hair are also at risk. With this in mind, measures should be taken to increase awareness and avoid the unnecessary usage of PPD in children.

Systemic contact dermatitis.

Systemic exposure to allergens resulting in a cutaneous eruption is known as systemic contact dermatitis (SCD). Once sensitization occurs, varying exposures to antigens via multiple routes (including transepidermal routes, intravenous or intramuscular routes, inhalation, and ingestion) can result in systemic flare. This article highlights the different categories of common contactants, metals, medications, and plants, exposure to which leads to SCD. A comprehensive approach that takes into account all possible routes of exposure is essential in diagnosing SCD and in helping patients successfully avoid their allergens.

Tetracycline suppresses ATP gamma S-induced CXCL8 and CXCL1 production by the human dermal microvascular endothelial cell-1 (HMEC-1) cell line and primary human dermal microvascular endothelial cells.

Tetracyclines (TCN) have powerful anti-inflammatory properties in addition to their anti-microbial effects. These anti-inflammatory effects are thought to play a role in inhibiting cutaneous inflammation in patients with rosacea and acne; however, the mechanism(s) of this action remains poorly understood. We have previously shown that adenosine-5'-triphosphate (ATP)gamma S, a hydrolysis-resistant ATP analogue, augments secretion of pro-inflammatory messengers by a human dermal microvascular endothelial cell line (HMEC-1). ATP released by the sympathetic nerves during stress may stimulate release of pro-inflammatory chemokines by dermal vessel endothelial cells, resulting in recruitment of inflammatory cells and exacerbation of inflammatory skin disease. Here we demonstrate that TCN inhibits ATP gamma S-induced release of pro-inflammatory mediators by HMEC-1 cells and primary human dermal microvascular endothelial cells. TCN dose-dependently inhibited ATP gamma S-induced augmentation of CXCL8 (interleukin-8) and CXCL1 (growth-regulated oncogene-alpha) production by HMEC-1 cells and primary human dermal endothelial cells in vitro. TCN and ATP gamma S did not affect HMEC-1 cell viability as determined by trypan-blue exclusion and cell counts. Inhibition of production of inflammatory mediators by endothelial cells may be one mechanism by which TCN improves inflammatory skin diseases. The ability to inhibit release of inflammatory mediators induced in HMEC-1 cells by purinergic agonists may be a useful way to screen for potential therapeutic agents for cutaneous inflammation.

Sensitivity to para-phenylenediamine and intolerance to hydrochlorothiazide.

para-Phenylenediamine (PPD) is a contact allergen that cross-reacts with a variety of medications, including thiazide diuretics and sulfonamides. We present the case of a 52-year-old African American atopic woman who came for evaluation of a severe eyelid dermatitis and recurrent outbreaks of acneiform (follicular-based) pruritic papules on her face, chest, and back. These symptoms presented after the patient was started on hydrochlorothiazide for hypertension. The patient also reported a history of eyelid dermatitis associated with "black hair dye." Patch testing revealed a positive reaction to para-phenylenediamine (1+) and Disperse Blue 106 (1+). It was suspected that the patient might be demonstrating cross-reactivity to hydrochlorothiazide and a flare-up reaction of the eyelid dermatitis. After her cardiologist changed her blood pressure medication, the patient's eyelid dermatitis and eruption cleared. This case highlights the impact of PPD sensitization on the medical care of a patient with hypertension and the importance of choosing safer PPD-free alternatives and minimizing PPD exposures.