FK506 (tacrolimus) causes pain sensation through the activation of transient receptor potential ankyrin 1 (TRPA1) channels

FK506 (tacrolimus) is an immunosuppressant widely used as an ointment in the treatment of atopic dermatitis. However, local application of FK506 can evoke burning sensations in atopic dermatitis patients, and its mechanisms are unknown. In this study, we found that FK506 activates transient receptor potential ankyrin 1 (TRPA1) channels. In Ca2+-imaging experiments, increases in intracellular Ca2+ concentrations ([Ca2+]i) by FK506 were observed in HEK293T cells expressing hTRPA1 or hTRPM8. FK506-induced currents were observed in HEK293T cells expressing hTRPA1 or mTRPA1, but less or not at all in cells expressing hTRPV1 or hTRPM8 using a patch-clamp technique. FK506 also evoked single-channel opening of hTRPA1 in an inside-out configuration. FK506-induced [Ca2+]i increases were also observed in TRPA1-expressing mouse primary sensory neurons. Furthermore, injection of FK506 evoked licking or biting behaviors and these behaviors were almost abolished in TRPA1 knockout mice. These results indicate that FK506 might cause pain sensations through TRPA1 activation.

Management of atopic dermatitis in the pediatric population

Atopic dermatitis, one of the most common skin disorders in young children, has a prevalence of 10% to 20% in the first decade of life. It is a chronic illness that requires a multifaceted treatment strategy in the setting of limited therapeutic options. Balancing safety concerns with efficacious treatment is of particular importance in the pediatric population. Parents of patients with atopic dermatitis turn to their primary caregivers for guidance regarding this physically demanding and psychologically stressful condition. In addition to serving as a review of atopic dermatitis, this article delves into the state-of-the-art therapeutic options and includes a detailed review of the differences between topical corticosteroids and topical calcineurin inhibitors. We also discuss new treatment strategies that are being used by atopic dermatitis specialists, such as comprehensive "education-as-intervention" models, wet wraps, bleach baths, and systemic immunomodulatory therapies.

Diagnosis and management of common dermatoses in children: atopic, seborrheic, and contact dermatitis

Atopic, seborrheic, and contact dermatitis can significantly reduce the quality of life of patients and their families. Although differing in specific aspects of their epidemiology, etiology, and pathobiology, all 3 dermatoses are common in the pediatric population, and they share a common treatment approach. Although effective and widely used to manage exacerbations of pediatric dermatitis, the use of topical corticosteroid remains a concern for some physicians and parents because of its potential for systemic absorption and adverse events associated with prolonged use. Newer additions to the dermatitis treatment algorithm, such as the topical calcineurin inhibitors, may provide an effective steroid-sparing treatment option. Adjuvant treatments, such as antihistamines, antifungals, and antibiotics, also can provide benefit in appropriate circumstances. As there is no cure for dermatitis, a comprehensive, multipronged management strategy of preventive measures, such as trigger avoidance and periodic pharmacologic treatment, will provide patients and caregivers with the best opportunity to successfully control the disease.

Topical calcineurin inhibitors in pediatric atopic dermatitis: a critical analysis of current issues

Atopic dermatitis (AD) is a common disease in children. Despite good skin care and trigger avoidance, many children with AD require pharmacologic treatment to manage their disease. In recent years, topical calcineurin inhibitors (TCIs) have been used as an alternative to topical corticosteroids to treat some children with AD. However, revisions to the US labeling for TCIs (i.e. a boxed warning and a medication guide) have generated concern among pediatricians regarding TCI safety and raised questions about the appropriate use of TCIs in the pediatric population. Data from several well designed studies support the efficacy of TCIs in the treatment of AD. Safety concerns arise from a small number of reported malignancies, animal toxicology studies, and the potential adverse effects (including immunosuppression and risk of lymphoma) observed in patients who received systemically administered calcineurin inhibitors for suppression of solid-organ transplant rejection. Several factors indicate that these effects do not occur with topical administration: (i) systemic levels following topical administration are at least 10-fold lower than with oral administration; (ii) the small number of lymphomas reported to date in persons exposed to TCI use are not consistent with the types seen in transplant patients or other immunosuppressed patients; and (iii) no adverse effects on the immune system (as assessed by measures including vaccination response and skin delayed-type hypersensitivity reaction) have been observed in clinical trials of TCIs in children with AD. Overall, TCIs have an established safety and efficacy profile as long-term maintenance therapy in children with AD.