Discovery of Topical Calcineurin Inhibitors and Pharmacological Profile of Pimecrolimus

Calcineurin Is a Universal Regulator of Vessel Function-Focus on Vascular Smooth Muscle Cells

Calcineurin, a serine/threonine phosphatase regulating transcription factors like NFaT and CREB, is well known for its immune modulatory effects and role in cardiac hypertrophy. Results from experiments with calcineurin knockout animals and calcineurin inhibitors indicate that calcineurin also plays a crucial role in vascular function, especially in vascular smooth muscle cells (VSMCs). In the aorta, calcineurin stimulates the proliferation and migration of VSMCs in response to vascular injury or angiotensin II administration, leading to pathological vessel wall thickening. In the heart, calcineurin mediates coronary artery formation and VSMC differentiation, which are crucial for proper heart development. In pulmonary VSMCs, calcineurin/NFaT signaling regulates the release of Ca2+, resulting in increased vascular tone followed by pulmonary arterial hypertension. In renal VSMCs, calcineurin regulates extracellular matrix secretion promoting fibrosis development. In the mesenteric and cerebral arteries, calcineurin mediates a phenotypic switch of VSMCs leading to altered cell function. Gaining deeper insights into the underlying mechanisms of calcineurin signaling will help researchers to understand developmental and pathogenetical aspects of the vasculature. In this review, we provide an overview of the physiological function and pathophysiology of calcineurin in the vascular system with a focus on vascular smooth muscle cells in different organs. Overall, there are indications that under certain pathological settings reduced calcineurin activity seems to be beneficial for cardiovascular health.

Emerging nanotechnology backed formulations for the management of atopic dermatitis

Atopic dermatitis is a prevalent chronic skin inflammation affecting 2.1 to 4.1% of adults globally. The complexity of its pathogenesis and the relapsing nature make it challenging to treat. Current treatments follow European Academy of Dermatology and Venerology guidelines, but advanced cases with recurring lesions lack effective therapies. To address this gap, researchers are exploring nanotechnology for targeted drug delivery. Nanoparticles offer benefits such as improved drug retention, stability, controlled release and targeted delivery through the disrupted epidermal barrier. This integrated review evaluates the current state of AD treatment and highlights the potential of novel nano-formulations as a promising approach to address the disease.

Influence of Molecular Structure and Physicochemical Properties of Immunosuppressive Drugs on Micelle Formulation Characteristics and Cutaneous Delivery

The aim of this study was to investigate whether subtle differences in molecular properties affected polymeric micelle characteristics and their ability to deliver poorly water-soluble drugs into the skin. D-α-tocopherol-polyethylene glycol 1000 was used to prepare micelles containing ascomycin-derived immunosuppressants-sirolimus (SIR), pimecrolimus (PIM) and tacrolimus (TAC)-which have similar structures and physicochemical properties and have dermatological applications. Micelle formulations were prepared by thin-film hydration and extensively characterized. Cutaneous delivery and biodistribution were determined and compared. Sub-10 nm micelles were obtained for the three immunosuppressants with incorporation efficiencies >85%. However, differences were observed for drug loading, stability (at the highest concentration), and their in vitro release kinetics. These were attributed to differences in drug aqueous solubility and lipophilicity. Differences between the cutaneous biodistribution profiles and drug deposition in the different skin compartments pointed to the impact of differences in thermodynamic activity. Therefore, despite their structural similarities, SIR, TAC and PIM did not demonstrate the same behaviour either in the micelles or when applied to the skin. These outcomes indicate that polymeric micelles should be optimized even for closely related drug molecules and support the hypothesis that drugs are released from micelles prior to skin penetration.

Advances in Current Drugs and Formulations for the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with a complex pathophysiology. Treatment of AD remains challenging owing to the presence of a wide spectrum of clinical phenotypes and limited response to existing therapies. However, recent genetic, immunological, and pathophysiological insights into the disease mechanism resulted in the invention of novel therapeutic drug candidates. This review provides a comprehensive overview of current therapies and assesses various novel drug delivery strategies currently under clinical investigation. Further, this review majorly emphasizes on various topical treatments including emollient therapies, barrier repair agents, topical corticosteroids (TCS), phosphodiesterase 4 (PDE4) inhibitors, calcineurin inhibitors, and Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway inhibitors. It also discusses biological and systemic therapies, upcoming treatments based on ongoing clinical trials. Additionally, this review scrutinized the use of pharmaceutical inactive ingredients in the approved topical dosage forms for AD treatment.

Experts' Consensus on the Use of Pimecrolimus in Atopic Dermatitis in China: A TCS-Sparing Practical Approach

Introduction

Atopic dermatitis (AD) is a chronic, pruritic, inflammatory skin disease with rising prevalence. Topical corticosteroids (TCS) are recommended as first-line therapy for patients with AD in China; however, corticophobia is a widespread concern, which can manifest as noncompliance: in a previous Chinese study, almost all parents whose children had AD were very concerned about the side effects of TCS and, as a result, nearly half did not use it in the event of recurrence. We propose a TCS-sparing treatment algorithm for the management of infants, children, adolescents, and adults with mild-to-moderate AD, to guide clinical practice in China.

Methods

A panel of eight experts in AD from China and one expert from Germany formed to develop a practical algorithm for the management of mild-to-moderate AD, focusing on pimecrolimus.

Results

Irrespective of body location, all patients with mild AD (including acute flares) and infants with moderate AD should apply the topical calcineurin inhibitor (TCI) pimecrolimus twice daily to the affected area until symptoms disappear. For children, adolescents, and adults with moderate AD, pimecrolimus should be applied twice daily to sensitive skin areas, and a TCI (either pimecrolimus or tacrolimus) should be applied twice daily to other body locations. Short-term administration of TCS, followed by TCI twice daily, is recommended for most patients with moderate AD experiencing acute flares, regardless of lesion site. Emollients should be used regularly.

Conclusions

The algorithm presented intends to simplify treatment of AD in China and guide clinical decision-making.

Topical therapy of atopic dermatitis with a focus on pimecrolimus

Atopic dermatitis (AD) is a chronic and relapsing, inflammatory skin disease characterized by impaired skin barrier function and immune system dysregulation that results in dryness, skin microbiome dysbiosis and intense pruritus. It is highly heterogeneous, and its management is demanding. Patients with AD are at greater risk of comorbidities such as attention-deficit hyperactivity disorder as well as other atopic diseases. Early-onset AD cases typically improve or resolve in late childhood; however, it is proposed that the prevalence of persistent or adult-onset AD is higher than previously thought. Basic therapy consists of emollient application and trigger avoidance, and when insufficient, topical corticosteroids (TCS) are the first-line treatment. However, corticophobia/steroid aversion and TCS side-effects, particularly on sensitive skin areas, lead to low compliance and insufficient disease control. Several long- and short-term randomized controlled and daily practice studies have demonstrated that topical calcineurin inhibitors, such as pimecrolimus, have similar anti-inflammatory effects to low-to-medium strength TCS, reduce pruritus and improve the quality of life of patients. In addition, pimecrolimus does not cause skin atrophy, is steroid-sparing and has a good safety profile, with no evidence for an increased risk of malignancies or skin infections. In general, pimecrolimus cream is well-accepted and well-tolerated, encouraging patient adherence and leading to its use by many physicians as a preferred therapy for children and sensitive skin areas.

No evidence of increased cancer incidence in children using topical tacrolimus for atopic dermatitis

BACKGROUND

Long-term safety of topical calcineurin inhibitors is not well understood. APPLES (A Prospective Pediatric Longitudinal Evaluation to Assess the Long-Term Safety of Tacrolimus Ointment for the Treatment of Atopic Dermatitis; NCT00475605) examined incidence of lymphoma and other cancers in a pediatric population with atopic dermatitis.

OBJECTIVE

To quantify incident malignancies during 10 years in children with atopic dermatitis who used topical tacrolimus for ≥6 weeks.

METHODS

Standardized incidence ratios for cancer events were analyzed relative to sex-, age-, and race-matched control data from national cancer registries.

RESULTS

There were 7954 eligible patients enrolled at 314 sites in 9 countries. During 44,629 person-years, 6 confirmed incident cancers occurred (standardized incidence ratio, 1.01; 95% confidence interval, 0.37-2.20). No lymphomas occurred.

LIMITATIONS

Observational prospective cohort study.

CONCLUSION

The cancer incidence was as expected, given matched background data. This finding provides no support for the hypothesis that topical tacrolimus increases long-term cancer risk in children with atopic dermatitis.

Childhood atopic dermatitis: current developments, treatment approaches, and future expectations

Atopic dermatitis (AD) is the most common chronic inflammatory skin disorder of childhood. Underlying factors that contribute to AD are impaired epithelial barrier, alterations in the lipid composition of the skin, immunological imbalance including increased Th2/Th1 ratio, proinflammatory cytokines, decreased T regulatory cells, genetic mutations, and epigenetic alterations. Atopic dermatitis is a multifactorial disease with a particularly complicated pathophysiology. Discoveries to date may be considered the tip of the iceberg, and the increasing number of studies in this field indicate that there are many points to be elucidated in AD pathophysiology. In this review, we aimed to illustrate the current understanding of the underlying pathogenic mechanisms in AD, to evaluate available treatment options with a focus on recently discovered therapeutic agents, and to determine the personal, familial, and economic burdens of the disease, which are frequently neglected issues in AD. Currently available therapies only provide transient solutions and cannot fully cure the disease. However, advances in the understanding of the pathogenic mechanisms of the disease have led to the production of new treatment options, while ongoing drug trials also have had promising results.

Topical pimecrolimus versus betamethasone for oral lichen planus: a randomized clinical trial

OBJECTIVES

Oral lichen plans (OLP) is a potentially malignant inflammatory mucocutaneous disease. CD133 is an investigated surface marker for cancer stem-like cells (CSCs) that may be involved in tumor initiation in head and neck carcinomas. We compared short-term clinical effectiveness of topical pimecrolimus as selective inflammatory cytokine release inhibitor with betamethasone cream for erosive/atrophic OLP and investigated the influence of this therapy on CD133 expression.

MATERIAL AND METHODS

Thirty patients were randomly assigned into two equal groups to receive topical pimecrolimus (group I) or betamethasone (group II) four times daily for 4 weeks. A marker lesion in each patient were assessed at baseline using clinical score (CS) and visual analog scale (VAS) then at 1, 2, and 4 weeks and after 4 weeks of treatment-free period. CD133 expression was detected in pre- and post-treatment immunostained sections.

RESULTS

Both drugs showed a reduction in CS, VAS, and CD133 expressions after treatment termination (p < 0.001). Pimecrolimus-treated lesions showed significant higher 1st week reduction in severity (33.1% (22.2)), pain score (57.53% (14.27)), less recurrence in follow-up period and less CD133 expression by the end of the 1st 4 weeks compared with betamethasone.

CONCLUSION

Pimecrolimus showed earlier clinical response and less recurrence rate compared with standard topical corticosteroid in symptomatic OLP lesions, and both treatment reduced CD133-positive CSC population.

CLINICAL RELEVANCE

The study proved the benefits of topical pimecrolimus in early management of painful lesions of OLP and its ability to inhibit CSCs, suggesting a possible role in reducing risk of malignant transformation.

Atopic dermatitis: a review of topical nonsteroid therapy

Background

Atopic dermatitis is a chronic inflammatory skin condition that affects up to 20% of children and 3% of adults globally. Although topical corticosteroids are considered to be the first-line agents, they can be associated with cutaneous and systemic adverse effects. Since the early 2000s, two new classes of nonsteroid topical therapies, topical calcineurin inhibitors and phosphodiesterase 4 (PDE4) inhibitors, have been introduced and provide a safe treatment alternative.

Method

We performed a search and review of clinical trials that examined the safety and efficacy of topical calcineurin inhibitors and PDE4 inhibitors. The search was conducted using the PubMed database as well as preselected keywords and filters. This review focuses on the safety and efficacy of each therapy.

Results

Sixty-nine clinical trials identified in this study have demonstrated the efficacy and safety of topical calcineurin and a single novel PDE4 inhibitor in the treatment of atopic dermatitis. Topical calcineurin inhibitors have been shown to be effective in both achieving lesion clearance as well as reducing relapse when used long-term and proactively. Similarly, in clinical trials the PDE4 inhibitor showed success in lesion clearance and symptom management. All three therapies (pimecrolimus, tacrolimus, crisaborole) are associated with low systemic absorption. No clinical trials to date have shown an increased risk of systemic adverse events or malignancy such as lymphoma. The most commonly reported treatment-related adverse event across all three therapies was application-site discomfort, pain or pruritus. It is important to note that long-term studies are not yet available for the novel PDE4 inhibitor.

Discussion

Topical calcineurin inhibitors provide a safe and effective alternative to topical corticosteroid use in the treatment of atopic dermatitis. Although the US Food and Drug Administration (FDA) black box warning for topical calcineurin inhibitors remains, studies have not shown an increased risk of malignancy. These warnings have caused a decline in use in favor of topical steroids. A novel PDE4 inhibitor has shown efficacy and safety in studies up to one year. Further long-term safety data is needed.

Combining metabolomics and network analysis to improve tacrolimus production in Streptomyces tsukubaensis using different exogenous feedings

Tacrolimus is widely used as an immunosuppressant in the treatment of various autoimmune diseases. However, the low fermentation yield of tacrolimus has thus far restricted its industrial applications. To solve this problem, the time-series response mechanisms of the intracellular metabolism that were highly correlated with tacrolimus biosynthesis were investigated using different exogenous feeding strategies in S. tsukubaensis. The metabolomic datasets, which contained 93 metabolites, were subjected to weighted correlation network analysis (WGCNA), and eight distinct metabolic modules and seven hub metabolites were identified to be specifically associated with tacrolimus biosynthesis. The analysis of metabolites within each metabolic module suggested that the pentose phosphate pathway (PPP), shikimate and aspartate pathway might be the main limiting factors in the rapid synthesis phase of tacrolimus accumulation. Subsequently, all possible key-limiting steps in the above metabolic pathways were further screened using a genome-scale metabolic network model (GSMM) of S. tsukubaensis. Based on the prediction results, two newly identified targets (aroC and dapA) were overexpressed experimentally, and both of the engineered strains showed higher tacrolimus production. Moreover, the best strain, HT-aroC/dapA, that was engineered to simultaneously enhanced chorismate and lysine biosynthesis was able to produce 128.19 mg/L tacrolimus, 1.64-fold higher than control (78.26 mg/L). These findings represent a valuable addition to our understanding of tacrolimus accumulation in S. tsukubaensis, and pave the way to further production improvements.

Treatment of Eczema: Corticosteroids and Beyond

Atopic dermatitis (AD) is a chronic inflammatory skin condition that requires a manifold approach to therapy. The goal of therapy is to restore the function of the epidermal barrier and to reduce skin inflammation. This can be achieved with skin moisturization and topical anti-inflammatory agents, such as topical corticosteroids and calcineurin inhibitors. Furthermore, proactive therapy with twice weekly use of both topical corticosteroids and calcineurin inhibitors in previously affected areas has been found to reduce the time to the next eczematous flare. Adjunctive treatment options include wet wrap therapy, anti-histamines, and vitamin D supplementation. Bacterial colonization, in particular Staphylococcus aureus, can contribute to eczematous flares and overt infection. Use of systemic antibiotics in infected lesions is warranted; however, empiric antibiotics use in uninfected lesions is controversial. Local antiseptic measures (i.e., bleach baths) and topical antimicrobial therapies can be considered in patients with high bacterial colonization. Difficult-to-treat AD is a complex clinical problem that may require re-evaluation of the initial diagnosis of AD, especially if the onset of disease occurs in adulthood. It may also necessitate evaluation for contact, food, and inhaled allergens that may exacerbate the underlying AD. There are a host of systemic therapies that have been successful in patients with difficult-to-treat AD, however, these agents are limited by their side effect profiles. Lastly, with further insight into the pathophysiology of AD, new biological agents have been investigated with promising results.

FkbN and Tcs7 are pathway-specific regulators of the FK506 biosynthetic gene cluster in Streptomyces tsukubaensis L19

FK506 (tacrolimus), which is produced by many Streptomyces strains, is clinically used as an immunosuppressive agent and for treatment of inflammatory skin diseases. Here, we identified that the FK506 biosynthetic gene cluster in an industrial FK506-producing strain Streptomyces tsukubaensis L19 is organized as eight transcription units. Two pathway-specific regulators, FkbN and Tcs7, involved in FK506 biosynthesis from S. tsukubaensis L19 were characterized in vivo and in vitro. FkbN activates the transcription of six transcription units in FK506 biosynthetic gene cluster, and Tcs7 activates the transcription of fkbN. In addition, the DNA-binding specificity of FkbN was determined. Finally, a high FK506-producing strain was constructed by overexpression of both fkbN and tcs7 in S. tsukubaensis L19, which improved FK506 production by 89 % compared to the parental strain.

Systematic review on the efficacy, safety, and cost-effectiveness of topical calcineurin inhibitors in atopic dermatitis

BACKGROUND

Topical calcineurin inhibitors (TCIs) are widely used as an alternative to topical corticosteroids (TCSs) in treating of atopic dermatitis, but their risk versus benefit compared with TCSs remains unclear.

OBJECTIVE

We performed a systematic review of the efficacy, safety, and cost-effectiveness of TCI compared with TCS and emollients.

METHODS

Published meta-analysis, systematic reviews, and individual studies from January 2005 to January 2015 on the comparative efficacy, safety, and cost-effectiveness of TCI against emollients and TCS were included.

RESULTS

Tacrolimus is comparable to TCS in efficacy, safety profile, and cost-effectiveness. Pimecrolimus has a similar safety profile compared with TCS, emollients, and tacrolimus. It is superior to emollients but inferior to TCS and tacrolimus in efficacy and cost-effectiveness. The association of tacrolimus with malignancy remains uncertain.

CONCLUSIONS

Tacrolimus is an efficacious and cost-effective alternative to TCS, but its benefits need to be weighed against its still uncertain risk for malignancy. Pimecrolimus is appropriate for mild atopic dermatitis when TCS or tacrolimus is unsuitable.

Topical calcineurin inhibitors and lymphoma risk: evidence update with implications for daily practice

Topical calcineurin inhibitors (TCIs), commercially available since 2000–2001, are the first and only topical medications approved for chronic treatment of atopic dermatitis (AD) in pediatric patients and remain a welcomed alternative to topical corticosteroids. In January 2006, the US Food and Drug Administration (FDA) issued a boxed warning requirement based on a theoretical risk of malignancy (including lymphoma) with TCI use. However, in the years since, analyses of epidemiologic and clinical data have failed to demonstrate a causal relationship between TCI use and malignancy or lymphoma risk, especially for pimecrolimus cream. In fact, the observed number of malignancies and lymphomas observed both in post-marketing surveillance and reported to the FDA using its adverse events reporting system is much lower among TCI-exposed patients than the expected number for the general population. Furthermore, among children enrolled in post-marketing pediatric registry studies for both tacrolimus and pimecrolimus followed for up to 5.5 years [10,724 patient-years (PY)] or 6.5 years (16,219 PY), respectively, the observed number of malignancies and lymphomas is very low and similar to the number expected for a sample of similar size in the general population. In addition to reporting these comparative malignancy and lymphoma data, this article provides a historical overview of the boxed warning requirement and critically evaluates the preclinical, clinical, and epidemiological evidence that has thus far failed to substantiate a relationship between TCI use and malignancy. The authors also provide practical clinical advice for optimizing AD management and patient care in the context of the boxed warning.

Topical calcineurin inhibitors for atopic dermatitis: review and treatment recommendations

Atopic dermatitis (AD) is an inflammatory skin disease commonly affecting children and managed by pediatricians, primary care physicians, allergists, and dermatologists alike. For many years, the only available topical pharmacological treatment was topical corticosteroids. This changed in 2000-2001, when topical formulations of two calcineurin inhibitors (tacrolimus and pimecrolimus) were approved for short-term or chronic intermittent treatment of AD in patients ≥ 2 years of age, in whom other treatments have been ineffective or contraindicated. These topical calcineurin inhibitors (TCIs) quickly became a popular treatment option due at least in part to concerns over adverse events associated with prolonged topical corticosteroid use, especially in children. However, based on theoretical concerns about a possible risk of lymphoma associated with TCI use, a Boxed Warning was placed on both products in 2006. Since then, despite an extensive body of evidence, no causal relationship has been demonstrated between TCI use and an increased risk of lymphoma; however, the US FDA has concluded that a link cannot be ruled out. In fact, based on post-marketing surveillance of spontaneous, literature, and solicited reports, we report here that the lymphoma incidence in the topical pimecrolimus-exposed population is up to approximately 54-fold less than that seen in the general US population. This review summarizes the mechanism of action of TCIs, the factors that prompted the Boxed Warning, and recent TCI safety and efficacy data. Based on these data, both topical corticosteroids and TCIs should have defined roles in AD management, with TCIs favored for sensitive skin areas (e.g., face) and instances where topical corticosteroids have proven ineffective, thereby minimizing the risk of adverse effects with both drug classes.

Gene expression is differently affected by pimecrolimus and betamethasone in lesional skin of atopic dermatitis

BACKGROUND

Topical corticosteroids and calcineurin inhibitors are well-known treatments of atopic dermatitis (AD) but differ in their efficacy and side effects. We recently showed that betamethasone valerate (BM) although clinically more efficient impaired skin barrier repair in contrast to pimecrolimus in AD.

OBJECTIVE

This study elucidates the mode of action of topical BM and pimecrolimus cream in AD.

METHODS

Lesional AD skin samples after topical treatment with either BM or pimecrolimus were subjected to gene expression profile analysis.

RESULTS

Betamethasone valerate resulted in a significant reduction in mRNA levels of genes encoding markers of immune cells and inflammation, dendritic cells, T cells, cytokines, chemokines, and serine proteases, whereas pimecrolimus exerted minor effects only. This corroborates the clinical finding that BM reduces inflammation more effectively than pimecrolimus. Genes encoding molecules important for skin barrier function were differently affected. Both BM and pimecrolimus normalized the expression of filaggrin and loricrin. BM, but not pimecrolimus, significantly reduced the expression of rate-limiting enzymes for lipid synthesis and the expression of involucrin and small proline-rich proteins, which covalently bind ceramides. This may explain the lack of restoration of functional stratum corneum layers observed after BM treatment.

CONCLUSION

The gene expression profiles are consistent with our previous findings that corticosteroids may exert a more potent anti-inflammatory effect but may impair the restoration of the skin barrier. Corticosteroids are still the main treatment for severe and acutely exacerbated AD; pimecrolimus may be preferable for long-term treatment and stabilization.

Novel chemobiosynthetic approach for exclusive production of FK506

FK506, a widely used immunosuppressant, is produced by industrial fermentation processes using various Streptomyces species. Independently of the strain, structurally related compound FK520 is co-produced, resulting in complex and costly isolation procedures. In this paper, we report a chemobiosynthetic approach for exclusive biosynthesis of FK506. This approach is based on the Streptomyces tsukubaensis strain with inactivated allR gene, a homologue of crotonyl-CoA carboxylase/reductase, encoded in the FK506 biosynthetic cluster. This strain produces neither FK506 nor FK520; however, if allylmalonyl-S-N-acetylcysteamine precursor is added to cultivation broth, the production of FK506 is reestablished without FK506-related by-products. Using a combination of metabolic engineering and chemobiosynthetic approach, we achieved exclusive production of FK506, representing a significant step towards development of an advanced industrial bioprocess.

The direct cellular target of topically applied pimecrolimus may not be infiltrating lymphocytes

BACKGROUND

Topically applied calcineurin inhibitors have been shown to be effective in the treatment of atopic dermatitis. When systemically administered, these agents cause immunosuppression via inhibition of calcineurin in lymphocytes. As topical agents, the mechanism of action is poorly defined.

OBJECTIVES

To test the hypothesis that skin-infiltrating lymphocytes are directly targeted when calcineurin inhibitors are applied to the skin.

METHODS

Ten patients with atopic dermatitis were treated with 1% pimecrolimus cream twice daily to target lesions. Skin biopsies were performed before and 48 h after beginning therapy. We assessed the cellular localization of NFAT1 and NFAT2 as a surrogate measure of intracellular calcineurin activity (e.g. increasing cytoplasmic localization with increasing calcineurin inhibition).

RESULTS

All patients showed a clinical response, at both 48 h and 2 weeks. As previously described, NFAT2 localized to the follicular keratinocytes, and its activation was partially inhibited by topical pimecrolimus. NFAT1 was found to be expressed by follicular and interfollicular keratinocytes, and its mostly nuclear localization was not affected by topical pimecrolimus therapy. Both NFAT1 and NFAT2 were found in the infiltrating lymphocytes. However, using both manual counting as well as an automated method to assess nuclear intensity of NFAT staining, we found that the proportion of infiltrating leucocytes with nuclear ('activated') NFAT did not change following therapy with pimecrolimus.

CONCLUSIONS

Our results suggest that topical pimecrolimus does not act primarily by inhibiting the calcineurin/NFAT axis in lymphocytes but may instead act by other mechanisms, possibly by decreasing NFAT2 activity in follicular keratinocytes.

Pimecrolimus 1% cream for oral erosive lichen planus: a 6-week randomized, double-blind, vehicle-controlled study with a 6-week open-label extension to assess efficacy and safety

OBJECTIVE

To assess the efficacy and safety of topical pimecrolimus 1% cream in the treatment of oral erosive lichen planus.

DESIGN

A 6-week randomized, double-blind, vehicle-controlled phase followed by a 6-week open-label phase.

SETTING

Outpatients of the Department of Dermatology, University of Utah.

PATIENTS

Twenty-one patients with oral erosive lichen planus were randomized and treated with either pimecrolimus 1% cream or vehicle cream.

INTERVENTION

Pimecrolimus 1% cream, or its vehicle, were applied twice daily for 6 weeks to each side of the mouth with a 2×2 inch gauze pad folded in half and placed directly on the erosive lesion.

MAIN OUTCOME MEASURES

Efficacy was based on clinical evaluation of Investigator's Global Assessment (IGA) of the overall severity of the disease, erythema, measurement of the size of any target erosion in millimetres, and assessment of spontaneous pain. Blood levels of pimecrolimus were monitored in all subjects on day 0 and repeated on day 7.

RESULTS

Pimecrolimus 1% cream was superior to vehicle cream in reducing mean IGA, pain, and erosion size. For the vehicle group that entered the open-label phase, pimecrolimus 1% cream improved the mean IGA, pain, erosion size, and erythema. Pimecrolimus levels were detected in nine out of 10 of the pimecrolimus-treated subjects. These levels were consistently low. The pimecrolimus cream was well-tolerated. No clinically relevant, drug-related adverse events were reported.

CONCLUSION

Pimecrolimus 1% cream was superior to vehicle in reducing pain, erythema, decreasing erosion size, and improving overall severity of disease when compared with vehicle treatment.

Spotlight on topical pimecrolimus in pediatric atopic dermatitis

Topical pimecrolimus 1% cream (Elidel) [hereafter referred to as topical pimecrolimus] is a nonsteroidal alternative in the treatment of pediatric atopic dermatitis. In vehicle-controlled, short-term, continuous-use trials in pediatric patients with mild to moderate atopic dermatitis, topical pimecrolimus was effective in treating disease symptoms. Topical pimecrolimus was effective in preventing disease flares and reducing the need for topical corticosteroids in longer term, intermittent-use trials. In addition, topical pimecrolimus was associated with improvements in the health-related quality of life of pediatric patients with atopic dermatitis and their parents. In vehicle-controlled trials, topical pimecrolimus was generally as well tolerated as vehicle. Topical pimecrolimus showed similar efficacy to topical tacrolimus 0.03% ointment in a short-term, continuous-use trial and the two agents had a generally similar tolerability profile. Although comparative data between topical pimecrolimus and topical corticosteroids are lacking in pediatric patients, and the long-term tolerability (beyond 1-2 years) of topical pimecrolimus is yet to be established, topical pimecrolimus is a useful agent in the management of pediatric patients with mild to moderate atopic dermatitis who do not achieve satisfactory treatment with other topical pharmacologic treatments, including topical corticosteroids.

Origin of the allyl group in FK506 biosynthesis

FK506 (tacrolimus) is a secondary metabolite with a potent immunosuppressive activity, currently registered for use as immunosuppressant after organ transplantation. FK506 and FK520 are biogenetically related natural products that are synthesized by combined polyketide synthase/nonribosomal peptide synthetase systems. The entire gene cluster for biosynthesis of FK520 from Streptomyces hygroscopicus var. ascomyceticus has been cloned and sequenced. On the other hand, the FK506 gene cluster from Streptomyces sp. MA6548 (ATCC55098) was sequenced only partially, and it was reasonable to expect that additional genes would be required for the provision of substrate supply. Here we report the identification of a previously unknown region of the FK506 gene cluster from Streptomyces tsukubaensis NRRL 18488 containing genes encoding the provision of unusual building blocks for FK506 biosynthesis as well as a regulatory gene. Among others, we identified a group of genes encoding biosynthesis of the extender unit that forms the allyl group at carbon 21 of FK506. Interestingly, we have identified a small independent diketide synthase system involved in the biosynthesis of the allyl group. Inactivation of one of these genes, encoding an unusual ketosynthase domain, resulted in an FK506 nonproducing strain, and the production was restored when a synthetic analog of the allylmalonyl-CoA extender unit was added to the cultivation medium. Based on our results, we propose a biosynthetic pathway for the provision of an unusual five-carbon extender unit, which is carried out by a novel diketide synthase complex.

Topical pimecrolimus: a review of its use in the management of pediatric atopic dermatitis

Topical pimecrolimus 1% cream (Elidel) [hereafter referred to as topical pimecrolimus] is a nonsteroidal alternative in the treatment of pediatric atopic dermatitis. In vehicle-controlled, short-term, continuous-use trials in pediatric patients with mild to moderate atopic dermatitis, topical pimecrolimus was effective in treating disease symptoms. Topical pimecrolimus was effective in preventing disease flares and reducing the need for topical corticosteroids in longer term, intermittent-use trials. In addition, topical pimecrolimus was associated with improvements in the health-related quality of life (HR-QOL) of pediatric patients with atopic dermatitis and their parents. In vehicle-controlled trials, topical pimecrolimus was generally as well tolerated as vehicle. Topical pimecrolimus showed similar efficacy to topical tacrolimus 0.03% ointment (hereafter topical tacrolimus) in a short-term, continuous-use trial and the two agents had a generally similar tolerability profile. Although comparative data between topical pimecrolimus and topical corticosteroids are lacking in pediatric patients, and the long-term tolerability (beyond 1-2 years) of topical pimecrolimus is yet to be established, topical pimecrolimus is a useful agent in the management of pediatric patients with mild to moderate atopic dermatitis who do not achieve satisfactory treatment with other topical pharmacologic treatments, including topical corticosteroids.

Twice-daily versus once-daily applications of pimecrolimus cream 1% for the prevention of disease relapse in pediatric patients with atopic dermatitis

The aim of this study is to compare twice-daily and once-daily applications of pimecrolimus cream 1% for prevention of atopic dermatitis relapses in pediatric patients. This multicenter trial enrolled 300 outpatients aged 2 to 17 years, with mild-to-severe atopic dermatitis. The patients were initially treated with twice-daily topical pimecrolimus until complete clearance or for up to 6 weeks (open-label period). Those who achieved a decrease of at least 1 point in the Investigator's Global Assessment score were then randomized to double-blind treatment with pimecrolimus cream 1% either twice daily or once daily for up to 16 weeks. Study medication was discontinued during periods of disease remission (Investigator's Global Assessment = 0). The primary efficacy end point of the double-blind phase was disease relapse (worsening requiring topical corticosteroids or additional/alternative therapy and confirmed by Investigator's Global Assessment score > or = 3 and pruritus score > or = 2). Of the 300 patients enrolled in the study, 268 were randomized to treatment with pimecrolimus cream 1% either twice daily or once daily (n = 134 in each group). The relapse rate was lower in the twice-daily dose group (9.9%) than that in the once-daily dose group (14.7%), but analysis of the time to disease relapse, using a Cox proportional model to adjust for confounding variables, did not show a statistically significant difference between treatment arms (hazard ratio: 0.64; 95% CI: 0.31-1.30). Treatment of active atopic dermatitis lesions with pimecrolimus cream 1% twice daily, followed by the once-daily dosing regimen, was sufficient to prevent subsequent atopic dermatitis relapses over 16 weeks in pediatric patients.

Differential effects of corticosteroids and pimecrolimus on the developing skin immune system in humans and mice

Atopic dermatitis arises primarily in early infancy. In these patients, corticosteroids are used especially with great caution because of their side effects. Calcineurin inhibitors such as pimecrolimus (PIM) could be useful, but safety concerns have been raised in particular because of the lack of knowledge about their effects on the developing skin immune system. This study was designed to investigate the impact of PIM and corticosteroids on epidermal cells (EC) in infants and newborn mice. We found that the percentage of unfractionated viable infant ECs was significantly decreased in the presence of beta-methasone-17-valerate (BMV) but not PIM. Exposure of unfractionated infant ECs to BMV but not to PIM and vehicle control caused a significant inhibition of the upregulation of CD86 molecules on Langerhans cells (LC). The release of cytokines by LCs and ECs, cultured in the presence of BMV and PIM, was not significantly reduced compared with controls. Topical corticosteroid but not PIM application onto newborn mice induced apoptosis in some LC precursors. Our data suggest that similar to the situation in adult skin, corticosteroids may impair LC maturation as well as viability of ECs in infants, effects not seen with PIM.

Binding of pimecrolimus and tacrolimus to skin and plasma proteins: implications for systemic exposure after topical application

Pimecrolimus and tacrolimus are calcineurin inhibitors used for the topical treatment of atopic dermatitis. Although structurally similar, they display specific differences including higher lipophilicity and lower skin permeation of pimecrolimus. The aim of the present study was to understand the reason for the differences in skin permeation; in addition, plasma protein binding of the two drugs was analyzed side by side as a basis for comparison of systemic exposure to free drug. Permeation of pimecrolimus and tacrolimus through a silicon membrane was found to be similar; therefore, we assumed that differences in skin permeation could be caused by differences in affinity to skin components. To test this hypothesis, we investigated binding of pimecrolimus and tacrolimus to a preparation of soluble human skin proteins. One binding protein of approximately 15 kDa, probably corresponding to macrophilin12, displayed a similar binding capacity for pimecrolimus and tacrolimus. However, less specific, nonsaturating binding to other proteins was approximately 3-fold higher for pimecrolimus. Because of the high local drug concentration after topical administration, the unspecific, high-capacity binding is probably dominating the permeation through skin. In plasma both drugs bound predominantly to lipoproteins, which may affect disposition differently from albumin binding. The unbound fraction of pimecrolimus in human plasma was approximately 9-fold lower compared with that of tacrolimus (0.4 +/- 0.1 versus 3.7 +/- 0.8%). In conclusion, these results provide an explanation for the observed lower systemic exposure to pimecrolimus than to tacrolimus after topical application and suggest that differences in systemic exposure to free drug might be even more pronounced.

Pimecrolimus enhances TLR2/6-induced expression of antimicrobial peptides in keratinocytes

Calcineurin inhibitors are potent inhibitors of T-cell-receptor mediated activation of the adaptive immune system. The effects of this class of drug on the innate immune response system are not known. Keratinocytes are essential to innate immunity in skin and rely on toll-like receptors (TLRs) and antimicrobial peptides to appropriately recognize and respond to injury or microbes. In this study we examined the response of cultured human keratinocytes to pimecrolimus. We observed that pimecrolimus enhances distinct expression of cathelicidin, CD14, and human beta-defensin-2 and beta-defensin-3 in response to TLR2/6 ligands. Some of these responses were further enhanced by 1,25 vitamin D3. Pimecrolimus also increased the functional capacity of keratinocytes to inhibit growth of Staphylococcus aureus and decreased TLR2/6-induced expression of IL-10 and IL-1beta. Furthermore, pimecrolimus inhibited nuclear translocation of NFAT and NF-kappaB in keratinocytes. These observations uncover a previously unreported function for pimecrolimus in cutaneous innate host defense.

Signal transducer and activator of transcription 1 decoy oligodeoxynucleotide suppression of contact hypersensitivity

BACKGROUND

Cytokines play a pivotal role in allergy development through activating signaling mechanisms, such as the Janus kinase/signal transducer and activator of transcription (STAT) pathway, which controls the expression of numerous proinflammatory genes.

OBJECTIVE

In comparison with 2 different corticosteroids and a calcineurin inhibitor, the efficacy of a STAT1 decoy oligodeoxynucleotide (dODN)-containing ointment on hapten-induced contact hypersensitivity was examined in 3 different animal models.

METHODS

After sensitization, the test compounds were administered before hapten challenge, after hapten challenge, or both to different sites of the animal skin. Subsequent erythema and edema formation was scored macroscopically, microscopically, or by a shift in ear weight. Biopsy specimens were taken and processed for histopathology, immunohistochemistry, and real-time PCR analyses.

RESULTS

Treatment with the STAT1 dODN but not the corresponding control ODN markedly improved the clinical signs of inflammation in all 3 animal models in a dose-related manner. In guinea pig skin this was accompanied by a distinct decrease in leukocyte infiltration into the dermis after 24 hours. In addition, expression of CD40, IFN-gamma, IL-1beta, IL-8, IL-12, and TNF-alpha was strongly attenuated. The dODN was equally effective in the domestic pig model when administered therapeutically, and its preventive effect in the mouse model lasted for more than 48 hours.

CONCLUSIONS

Altogether, treatment with the dODN proved to be at least as effective as treatment with the reference compounds.

Topische Immunmodulation

BACKGROUND

Recurrent exacerbation of chronic external otitis represents a special challenge for the attending physician. The goal of our study was to evaluate the effectiveness of novel topical immunomodulators acting through an anti-inflammatory, nonsteroidal mechanism.

PATIENTS AND METHODS

In a prospective study, in 33 patients an ear wick containing tacrolimus ointment (Protopic 0.1%) was inserted every 2-3 days. Altogether, the wick was changed three times. Therapeutic outcomes were assessed by reexaminations, video-otoscopy, and a standardized findings sheet.

RESULTS

Twenty-eight patients showed significant improvement of clinical symptoms, with 13 of them showing complete healing (follow-up 10-22 months). Relapses (15 cases) were associated with significantly extended symptom-free intervals and reduced numbers of further recurrent episodes.

CONCLUSIONS

Because of the safe and successful anti-inflammatory effects, topical immunomodulators represent a new alternative in chronic inflammatory stages of otherwise therapy-resistant external otitis.

Inhibition of T-cell activation in vitro in human peripheral blood mononuclear cells by pimecrolimus and glucocorticosteroids and combinations thereof

Pimecrolimus is an ascomycin macrolactam derivative that has been recently approved for the topical treatment of atopic dermatitis. In this study we report for the first time on a direct comparison of the inhibitory activity of pimecrolimus and the glucocorticosteroids betamethasone 17-valerate, dexamethasone and hydrocortisone at the level of T-cell proliferation and cytokine production. Stimulated human peripheral blood mononuclear cell (PBMC) systems were used that are either sensitive or resistant to calcineurin inhibitors or glucocorticosteroids. Pimecrolimus and the glucocorticosteroids inhibited dose-dependently T-cell proliferation and cytokine production in a sensitive system (anti-CD3 mAb-stimulated PBMC) with the following rank order of potency: pimecrolimus approximately betamethasone 17-valerate approximately dexamethasone > hydrocortisone. In resistant systems (anti-CD3 plus anti-CD28- or Staphylococcal enterotoxin B-stimulated PBMC), pimecrolimus or the glucocorticosteroids alone exerted either no effect, or only a partial inhibitory effect. However, combinations of pimecrolimus with a glucocorticosteroid synergistically and strongly inhibited T-cell proliferation. Taken together, the data indicate that medium potency glucocorticosteroids, such as betamethasone 17-valerate and dexamethasone, are as potent T-cell inhibitors as pimecrolimus. Furthermore, the experimental evidence suggests that combinations of glucocorticosteroids and pimecrolimus could be used clinically to achieve superior therapeutic efficacy, when monotherapy with the individual agents is unsatisfactory.

Advances in swine biomedical model genomics

This review is a short update on the diversity of swine biomedical models and the importance of genomics in their continued development. The swine has been used as a major mammalian model for human studies because of the similarity in size and physiology, and in organ development and disease progression. The pig model allows for deliberately timed studies, imaging of internal vessels and organs using standard human technologies, and collection of repeated peripheral samples and, at kill, detailed mucosal tissues. The ability to use pigs from the same litter, or cloned or transgenic pigs, facilitates comparative analyses and genetic mapping. The availability of numerous well defined cell lines, representing a broad range of tissues, further facilitates testing of gene expression, drug susceptibility, etc. Thus the pig is an excellent biomedical model for humans. For genomic applications it is an asset that the pig genome has high sequence and chromosome structure homology with humans. With the swine genome sequence now well advanced there are improving genetic and proteomic tools for these comparative analyses. The review will discuss some of the genomic approaches used to probe these models. The review will highlight genomic studies of melanoma and of infectious disease resistance, discussing issues to consider in designing such studies. It will end with a short discussion of the potential for genomic approaches to develop new alternatives for control of the most economically important disease of pigs, porcine reproductive and respiratory syndrome (PRRS), and the potential for applying knowledge gained with this virus for human viral infectious disease studies.