Innovative use of topical calcineurin inhibitors

Optimization of the precursor supply for an enhanced FK506 production in Streptomyces tsukubaensis

Tacrolimus (FK506) is a macrolide widely used as immunosuppressant to prevent transplant rejection. Synthetic production of FK506 is not efficient and costly, whereas the biosynthesis of FK506 is complex and the level produced by the wild type strain, Streptomyces tsukubaensis, is very low. We therefore engineered FK506 biosynthesis and the supply of the precursor L-lysine to generate strains with improved FK506 yield. To increase FK506 production, first the intracellular supply of the essential precursor lysine was improved in the native host S. tsukubaensis NRRL 18488 by engineering the lysine biosynthetic pathway. Therefore, a feedback deregulated aspartate kinase AskSt* of S. tsukubaensis was generated by site directed mutagenesis. Whereas overexpression of AskSt* resulted only in a 17% increase in FK506 yield, heterologous overexpression of a feedback deregulated AskCg* from Corynebacterium glutamicum was proven to be more efficient. Combined overexpression of AskCg* and DapASt, showed a strong enhancement of the intracellular lysine pool following increase in the yield by approximately 73% compared to the wild type. Lysine is coverted into the FK506 building block pipecolate by the lysine cyclodeaminase FkbL. Construction of a ∆fkbL mutant led to a complete abolishment of the FK506 production, confirming the indispensability of this enzyme for FK506 production. Chemical complementation of the ∆fkbL mutant by feeding pipecolic acid and genetic complementation with fkbL as well as with other lysine cyclodeaminase genes (pipAf, pipASt, originating from Actinoplanes friuliensis and Streptomyces pristinaespiralis, respectively) completely restored FK506 production. Subsequently, FK506 production was enchanced by heterologous overexpression of PipAf and PipASp in S. tsukubaensis. This resulted in a yield increase by 65% compared to the WT in the presence of PipAf from A. friuliensis. For further rational yield improvement, the crystal structure of PipAf from A. friuliensis was determined at 1.3 Å resolution with the cofactor NADH bound and at 1.4 Å with its substrate lysine. Based on the structure the Ile91 residue was replaced by Val91 in PipAf, which resulted in an overall increase of FK506 production by approx. 100% compared to the WT.

Bioengineering of Anti-Inflammatory Natural Products

Inflammatory processes occur as a generic response of the immune system and can be triggered by various factors, such as infection with pathogenic microorganisms or damaged tissue. Due to the complexity of the inflammation process and its role in common diseases like asthma, cancer, skin disorders or Alzheimer's disease, anti-inflammatory drugs are of high pharmaceutical interest. Nature is a rich source for compounds with anti-inflammatory properties. Several studies have focused on the structural optimization of natural products to improve their pharmacological properties. As derivatization through total synthesis is often laborious with low yields and limited stereoselectivity, the use of biosynthetic, enzyme-driven reactions is an attractive alternative for synthesizing and modifying complex bioactive molecules. In this minireview, we present an outline of the biotechnological methods used to derivatize anti-inflammatory natural products, including precursor-directed biosynthesis, mutasynthesis, combinatorial biosynthesis, as well as whole-cell and in vitro biotransformation.

Comparison of topical clobetasol propionate 0.05% and topical tacrolimus 0.1% in the treatment of cutaneous lichen planus

Introduction

The effectiveness of topical tacrolimus in the treatment of oral and genital lichen planus has been verified in many randomized studies; however, there are only few case reports in treatment of cutaneous lichen planus (CLP).

Aim

We sought to compare the safety and efficacy of topical clobetasol propionate and tacrolimus ointment in the treatment of CLP.

Material and methods

Retrospective analysis of patient files was performed. We enrolled patients who were diagnosed with CLP and treated with topical tacrolimus 0.1% or topical clobetasol propionate 0.05%. Visual Analogue Scale (VAS) scores of pigmentation and pruritus, clinical response, laboratory data and adverse effects were obtained from medical records.

Results

A total of 27 patients were included in the clobetasol group and 23 patients in the tacrolimus group. Both groups showed an improvement in VAS scores regarding pruritus and pigmentation but a statistically significant difference was observed in the clobetasol group (p< 0.05). At week 12, a complete response was observed in 63% (n = 17) of the clobetasol and 26% (n = 6) of the tacrolimus group.

Conclusions

In our study, both treatments were found effective in the treatment of CLP but clobetasol propionate was more effective. However tacrolimus may be preferred before topical corticosteroids for lesions on the face, neck, and intertriginous regions of the body, which are sensitive to the cutaneous adverse effects of topical corticosteroids. Our study may be one of the first studies to compare the effects of topical clobetasol and tacrolimus ointment in the management of CLP.

Beyond the Booth: Excimer Laser for Cutaneous Conditions

The excimer laser has emerged as an efficacious treatment modality for many dermatologic diseases. The excimer laser is an alternative to standard narrowband ultraviolet B (NBUVB) phototherapy treatment in patients with limited disease. In comparison to standard NBUVB, the excimer laser requires fewer treatment sessions, has reduced treatment duration, requires a lower cumulative UVB dose, and limits UVB exposure to lesional skin. This review addresses the mechanism, safety, application, and efficacy of the excimer laser for the treatment of these conditions.

Efficacy of Topical Calcineurin Inhibitors in Oral Lichen Planus

Background:

Oral lichen planus (OLP) is associated with severe pain and significant impairment for patients.

Objective:

To evaluate the safety and efficacy of topical calcineurin inhibitors (TCI) in the treatment of OLP.

Methods:

Medline and the Cochrane Database were searched using the keywords “calcineurin inhibitor OR tacrolimus OR pimecrolimus” AND “oral lichen planus.”

Results:

Four retrospective studies that looked at the effects of tacrolimus on OLP; 4 randomized, double-blind clinical trials (RDBCT) comparing tacrolimus with topical corticosteroids; and 5 RDBCT comparing pimecrolimus with placebo or triamcinolone were noted. Six open prospective and multiple case reports assessing the efficacy of calcineurin inhibitor for treatment of diverse types of OLP were found.

Conclusion:

There is strong evidence to suggest that the use of tacrolimus 0.1% ointment and pimecrolimus 1% cream is superior or equally efficacious as traditional therapies for OLP. Topical calcineurin inhibitors are well tolerated, with no significant systemic adverse effects.

Topical anti-inflammatory agents for seborrhoeic dermatitis of the face or scalp

BACKGROUND

Seborrhoeic dermatitis is a chronic inflammatory skin disorder affecting primarily the skin of the scalp, face, chest, and intertriginous areas, causing scaling and redness of the skin. Current treatment options include antifungal, anti-inflammatory, and keratolytic agents, as well as phototherapy.

OBJECTIVES

To assess the effects of topical pharmacological interventions with established anti-inflammatory action for seborrhoeic dermatitis occurring in adolescents and adults.

SEARCH METHODS

We searched the following databases up to September 2013: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2013, Issue 9), MEDLINE (from 1946), Embase (from 1974), LILACS (from 1982), and the GREAT database. We searched five trials databases and checked the reference lists of included studies for further references to relevant randomised controlled trials (RCTs).

SELECTION CRITERIA

We included RCTs in adults or adolescents (> 16 years) with diagnosed seborrhoeic dermatitis of the scalp or face, comparing topical anti-inflammatory treatments (steroids, calcineurin inhibitors, and lithium salts) with other treatments.

DATA COLLECTION AND ANALYSIS

Pairs of authors independently assessed eligibility for inclusion, extracted data, and evaluated the risk of bias. We performed meta-analyses if feasible.

MAIN RESULTS

We included 36 RCTs (2706 participants), of which 31 examined topical steroids; seven, calcineurin inhibitors; and three, lithium salts. The comparative interventions included placebo, azoles, calcipotriol, a non-steroidal anti-inflammatory compound, and zinc, as well as different anti-inflammatory treatments compared against each other. Our outcomes of interest were total clearance of symptoms, erythema, scaling or pruritus scores, and adverse effects. The risk of bias in studies was most frequently classified as unclear, due to unclear reporting of methods.Steroid treatment resulted in total clearance more often than placebo in short-term trials (four weeks or less) (relative risk (RR) 3.76, 95% confidence interval (CI) 1.22 to 11.56, three RCTs, 313 participants) and in one long-term trial (lasting 12 weeks). Steroids were also more effective in reducing erythema, scaling, and pruritus. Adverse effects were similar in both groups.There may be no difference between steroids and calcineurin inhibitors in total clearance in the short-term (RR 1.08, 95% 0.88 to 1.32, two RCTs, 60 participants, low-quality evidence). Steroids and calcineurin inhibitors were found comparable in all other assessed efficacy outcomes as well (five RCTs, 237 participants). Adverse events were less common in the steroid group compared with the calcineurin group in the short-term (RR 0.22, 95% CI 0.05 to 0.89, two RCTs, 60 participants).There were comparable rates of total clearance in the steroid and azole groups (RR 1.11, 95% CI 0.94 to 1.32, eight RCTs, 464 participants, moderate-quality evidence) as well as of adverse effects in the short-term, but less erythema or scaling with steroids.We found mild (class I and II) and strong (class III and IV) steroids comparable in the assessed outcomes, including adverse events. The only exception was total clearance in long-term use, which occurred more often with a mild steroid (RR 0.79, 95% CI 0.63 to 0.98, one RCT, 117 participants, low-quality evidence).In one study, calcineurin inhibitor was more effective than placebo in reducing erythema and scaling, but there were similar rates in total clearance or adverse events for short-term treatment. In another study, calcineurin inhibitor was comparable with azole when erythema, scaling, or adverse effects were measured for longer-term treatment.Lithium was more effective than placebo with regard to total clearance (RR 8.59, 95% CI 2.08 to 35.52, one RCT, 129 participants) with a comparable safety profile. Compared with azole, lithium resulted in total clearance more often (RR 1.79, 95% CI 1.10 to 2.90 in short-term treatment, one RCT, 288 participants, low-quality evidence).

AUTHORS' CONCLUSIONS

Topical steroids are an effective treatment for seborrhoeic dermatitis of the face and scalp in adolescents and adults, with no differences between mild and strong steroids in the short-term. There is some evidence of the benefit of topical calcineurin inhibitor or lithium salt treatment. Treatment with azoles seems as effective as steroids concerning short-term total clearance, but in other outcomes, strong steroids were more effective. Calcineurin inhibitor and azole treatment appeared comparable. Lithium salts were more effective than azoles in producing total clearance.Steroids are similarly effective to calcineurin inhibitors but with less adverse effects.Most of the included studies were small and short, lasting four weeks or less. Future trials should be appropriately blinded; include more than 200 to 300 participants; and compare steroids to calcineurin inhibitors or lithium salts, and calcineurin inhibitors to azoles or lithium salts. The follow-up time should be at least one year, and quality of life should be addressed. There is also a need for the development of well-validated outcome measures.

Trends in the biosynthesis and production of the immunosuppressant tacrolimus (FK506)

The current off-patent state of tacrolimus (FK506) has opened the hunting season for new generic pharmaceutical formulations of this immunosuppressant. This fact has boosted the scientific and industrial research on tacrolimus for the last 5 years in order to improve its production. The fast discovery of tacrolimus producer strains has generated a huge number of producers, which presents the biosynthetic cluster of FK506 as a high promiscuous genetic region. For the first time, the current state-of-the-art on the tacrolimus biosynthesis, production improvements and drug purification is reviewed. On one hand, all the genes involved in the tacrolimus biosynthesis, in addition to the traditional PKS/NRPS, as well as their regulation are analysed. On the other hand, tacrolimus direct and indirect precursors are reviewed as a straight manner to improve the final yield, which is a current trend in the field. Twenty years of industrial and scientific improvements on tacrolimus production are summarised, whereas future trends are also drafted.

[Off-label use and G-BA. Legal framework for off-label use]

Off-label use of medicinal products, i.e. beyond their submitted, tested and approved indications, lies between 30 and 90%--depending on the indication. In dermatology, off-label use is of special importance, for even guideline-endorsed standard therapeutic approaches for common dermatological diseases like atopic eczema, psoriasis, or malignant melanoma are to some extent not licensed for these indications. In addition, many of the approximately 5000 dermatological diseases have a low prevalence. For many such orphan diseases, there are no approved drugs, and it is not feasible that licensing studies will be performed for these indications within a foreseeable time. A reliable legal framework for the reimbursement of medicinal products that are used off-label is essential both for patients and to allow physicians to choose the most adequate therapy. Therefore, off-label use expert groups have been convened by the Federal Ministry of Health (BMG) in order to improve patient care. So far this new and innovative approach has not provided any reasonable improvement for many patients with dermatological diseases whose treatment can only be off-label since a comprehensive evaluation of all off-label indications is not possible. The following statement of the former Federal Minister of Health, U. Schmidt, is particularly true for dermatological therapy: "Good oncologic care also requires a good drug treatment--especially in the outpatient setting. The use of drugs which are not or not yet approved for this indication is often required here". Federal Minister of Health, Ulla Schmidt, 25th German Cancer Congress, 10 March 2002, Berlin.

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.

Nail psoriasis: a review

Nail psoriasis is common, occurring in up to half of patients with psoriasis and in 90% of patients with psoriatic arthritis. Left untreated, it may progress to debilitating nail disease, which leads to significant functional impairment. The most common clinical signs of nail psoriasis are nail plate pitting and onycholysis. Other classical signs include oil drop discoloration, subungual hyperkeratosis, and splinter hemorrhages. The modified Nail Psoriasis Severity Index (mNAPSI) can be used to grade the severity of nail psoriasis, while the Nail Psoriasis Quality of Life Scale (NPQ10) is a questionnaire that evaluates the impact of nail psoriasis on the patient's functional status and quality of life. Treatment of nail psoriasis should be individualized according to the patient's preferences, severity of nail changes, and presence of skin and/or joint involvement. Both topical and intralesional therapies are safe and effective treatment modalities for nail disease, but are limited by poor adherence and pain, respectively. Systemic therapy such as oral retinoids may be considered for widespread nail disease causing significant morbidity. Among biologic agents, tumor necrosis factor-α inhibitors and T-cell-targeted therapies such as ustekinumab may be useful for refractory severe nail psoriasis.

Clinical application of development of nonantibiotic macrolides that correct inflammation-driven immune dysfunction in inflammatory skin diseases

BACKGROUND

Inflammation-driven immune dysfunction supports the development of several chronic human disorders including skin diseases. Nonantibiotic macrolides have anti-inflammatory and/or immunomodulatory activity that suggests the exploitation of these in the treatment of skin diseases characterized by inflammatory disorders.

MATERIALS AND METHODS

We performed an extensive review of the nonantibiotic macrolide literature published between 2005 and 2012, including cross-references of any retrieved articles. We also included some data from our own experience.

RESULTS

Calcineurin antagonists such as tacrolimus and ascomycins (e.g., pimecrolimus) act by inhibiting the activation of the nuclear factor for activated T cells (NFAT). There are new applications for these macrolides that have been available for several years and have been applied to skin and hair disorders such as atopic dermatitis, oral lichen planus, vitiligo, chronic autoimmune urticaria, rosacea, alopecia areata, pyoderma gangrenosum, Behcet's disease, neutrophilic dermatosis, and lupus erythematosus. We also reviewed new macrolides, like rapamycin, everolimus, and temsirolimus. In addition to the literature review, we report a novel class of nonantibiotic 14-member macrocycle with anti-inflammatory and immunomodulatory effects.

CONCLUSIONS

This paper summarizes the most important clinical studies and case reports dealing with the potential benefits of nonantibiotic macrolides which have opened new avenues in the development of anti-inflammatory strategies in the treatment of cutaneous disorders.

Efficacy of Topical Calcineurin Inhibitors in Lichen Planus

Background:

Topical calcineurin inhibitors have been studied in many skin disorders, including lichen planus.

Objective:

To evaluate published reports of the use of topical calcineurin inhibitors in lichen planus.

Methods:

We searched PubMed, Ovid/Cochrane, and Embase using the keywords “tacrolimus,” “pimecrolimus,” “topical calcineurin inhibitors,” and “lichen planus.”

Results:

We examined 5 double-blind studies, 1 investigator-blinded study, 10 open prospective studies, 6 retrospective studies, and 28 case reports evaluating tacrolimus or pimecrolimus for oral, vulvovaginal, and cutaneous lichen planus.

Conclusions:

Strong evidence (double-blind and open studies) supports the use of topical tacrolimus ointment in oral lichen planus, with efficacy at least equal to topical clobetasol propionate 0.05% ointment. Treatment of oral lichen planus with topical tacrolimus ointment can result in demonstrable blood tacrolimus levels, but without clinically significant adverse events. Strong evidence (double-blind and open studies) supports the use of topical pimecrolimus 1% cream in oral lichen planus, with efficacy equal to that of topical triamcinolone acetonide 0.1% paste. For vulvovaginal lichen planus, pimecrolimus was superior to placebo in one double-blind study, and tacrolimus was effective in open studies. Only case reports support the efficacy of topical calcineurin inhibitors in cutaneous lichen planus.

Update on the use of topical calcineurin inhibitors in cutaneous lupus erythematosus

Cutaneous manifestations of lupus erythematosus (CLE) are manifold, presenting with unspecific skin manifestations or well-defined clinical dermatological entities. Their relation to each other as well as to systemic lupus erythematosus is variable, yet diagnostically and therapeutically challenging. Therapeutic decisions have to be based on the activity and distribution as well as the type of skin lesions and the extent of systemic disease. Limited skin manifestations may be amply tackled by topical therapy, so far, mainly relying on corticosteroids. In many cases, however, internal treatment has to be combined by using antimalarials, in addition to strict UV-protection. The advent of topical calcineurin inhibitors has contributed substantially to the armamentarium of external treatment options. By specifically interfering with intracytoplasmic signal transduction to activate the nuclear factor of activated T-cells (NF-AT), they are able to modulate various inflammatory mechanisms. The two available compounds, pimecrolimus and tacrolimus, do not induce the skin atrophy characteristic of corticosteroids. They have been studied in a number of case reports, but only in a few randomized, comparative studies. Both are well-tolerated, but differentially effective in the various subsets of CLE. Further studies are needed to directly compare the two compounds to each other, as well as to topical corticosteroids, before final recommendations can be made.

Bullous lichen planus in childhood – A case report / Bulozni lichen planus u dečijem uzrastu

In Europe, only 1% of all patients with lichen planus are children. We report a case of lichen planus in a 5-year-old boy with blisters developing on papules. There was no history of Hepatitis B virus vaccination in the past 12 months. Routine laboratory analyses showed no abnormalities. Hepatitis B surface antigen and anti-Hepatitis C virus antibodies were negative. Our patient had disseminated and coalesced papules on the trunk and extremities with vesicles and bullae on the hands and feet. Histopathology confirmed the diagnosis of lichen planus and bullous lichen planus. Negative direct immunofluorscence test excluded lichen planus pemphigoides. The boy was treated with prednisone 1 mg/kg/ day (the dose was gradually tapered and discontinued over the next 1.5 month), ultraviolet B phototherapy, fluocinolon acetonide, and topical pimecrolimus 1% cream till complete remission after 2.5 months. Bullous form of lichen planus is seen in 1-16% of all children with lichen planus. Two months upon the completion of therapy, there were no signs of relapse. In our case, short course of systemic corticosteroids and ultraviolet B phototherapy have been safe and effective. This was the only pediatric case of bullous lichen planus treated in our Clinic in the last 20 years. Long-term prognosis of childhood lichen planus is not predictable, and there is no consensus regarding the treatment of childhood lichen planus.