Mechanism of Action and Emerging Role of Immune Response Modifier Therapy in Dermatologic Conditions

Vitiligo: From Pathogenesis to Treatment

Recent advances in vitiligo have provided promising treatment options, particularly through understanding the immune-mediated mechanisms leading to depigmentation. The inflammatory components in both vitiligo (non-segmental) and segmental vitiligo have similarities. Both are believed to result from an immune-based destruction of melanocytes by anti-melanocyte-specific cytotoxic T cells. The JAK-STAT pathway is activated with IFN-γ as the crucial cytokine and Th1-associated chemokines such as CXCL9 and CXCL10 recruit immune cells towards vitiligo skin. Nonetheless, clear differences are also present, such as the localized nature of segmental vitiligo, likely due to somatic mosaicism and increased presence of poliosis. The differing prevalence of poliosis suggests that the follicular immune privilege, which is known to involve immune checkpoints, may be more important in vitiligo (non-segmental). Immunomodulatory therapies, especially those targeting the JAK-IFNγ pathway, are currently at the forefront, offering effective inhibition of melanocyte destruction by cytotoxic T cells. Although Janus Kinase (JAK) inhibitors demonstrate high repigmentation rates, optimal results can take several months to years. The influence of environmental UV exposure on repigmentation in patients receiving immunomodulating drugs remains largely underexplored. Nonetheless, the combined effect of phototherapy with JAK inhibitors is impressive and suggests a targeted immune-based treatment may still require additional stimulation of melanocytes for repigmentation. Identifying alternative melanocyte stimulants beyond UV light remains crucial for the future management of vitiligo.

The role of MPL and imiquimod adjuvants in enhancement of immune response and protection in BALB/c mice immunized with soluble Leishmania antigen (SLA) encapsulated in nanoliposome

Adjuvants play an essential role in the induction of immunity against leishmaniasis. In this study, monophosphoryl lipid A (MPL) and imiquimod (IMQ) were used as TLR ligands adjuvants to enhance immunogenicity and rate of protection against leishmaniasis. Nanoliposomes containing soluble Leishmania antigens (SLA) and adjuvants were consisted of DSPC, DSPG and Chol prepared by using lipid film method followed by bath sonication. The size of nanoliposomes was around 95 nm and their zeta potential was negative. BALB/c mice were immunized by liposomal formulations of lip/SLA, lip/MPL/SLA, lip/IMQ/SLA, lip/MPL/IMQ/SLA, lip/SLA + lip/IMQ, lip/SLA + lip/MPL, lip/SLA + lip/MPL/IMQ and five controls of SLA, lip/MPL, lip/IMQ, lip/MPL/IMQ and buffer by subcutaneously (SC) injections, three times in 2 weeks intervals. The synergic effect of two adjuvants when they are used in one formulation showed significantly (p < .001) smaller footpad swelling and the lowest parasite burden in lymph node and foot after the challenge. IgG2a in these groups showed the higher titre compared to control groups, which is compatible with the high IFN-γ production and lowest IL-4. Taken together the results indicated that co-delivery of MPL and IMQ adjuvants and antigen in nanoliposome carrier could be an appropriate delivery system to induce cellular immunity pathway against leishmaniasis.

Photodynamic therapy is more effective than imiquimod for actinic keratosis in organ transplant recipients: a randomized intraindividual controlled trial

BACKGROUND

Actinic keratoses (AKs) in solid organ transplant recipients (OTRs) are difficult-to-treat premalignancies and comparison of topical therapies is therefore warranted.

OBJECTIVES

In an intraindividual study to compare the efficacy and safety of field treatment with methyl aminolaevulinate photodynamic therapy (MAL-PDT) and imiquimod (IMIQ) for AKs in OTRs.

METHODS

OTRs (n = 35) with 572 AKs (grade I-III) in two similar areas on the face, scalp, dorsal hands or forearms were included. All patients received one MAL-PDT and one IMIQ session (three applications per week for 4 weeks) in each study area according to randomization. Treatments were repeated after 2 months (IMIQ) and 3 months (PDT) in skin with incomplete AK response. Outcome measures were complete lesion response (CR), skin reactions, laboratory results and treatment preference.

RESULTS

The majority of study areas received two treatment sessions (PDT n = 25 patients; IMIQ n = 29 patients). At 3 months after two treatments, skin treated with PDT achieved a higher rate of CR (AK I-III median 78%; range 50-100) compared with IMIQ-treated skin areas (median 61%, range 33-100; P < 0·001). Fewer emergent AKs were seen in PDT-treated skin vs. IMIQ-treated skin (0·7 vs. 1·5 AKs, P = 0·04). Patients developed more intense inflammatory skin reactions following PDT, which resolved more rapidly compared with IMIQ (median 10 days vs. 18 days, P < 0·01). Patient preference (P = 0·47) and cosmesis (P > 0·30) were similar for PDT and IMIQ.

CONCLUSIONS

Compared with IMIQ, PDT treatment obtained a higher rate of AK clearance at 3-month follow-up and achieved shorter-lasting, but more intense, short-term skin reactions.

Basal Cell Carcinoma: Review of Epidemiology, Pathogenesis, and Associated Risk Factors

Background:

Basal cell carcinoma (BCC) is extremely common, and its incidence continues to rise.

Objective:

This review presents the literature pertaining to the epidemiology, pathogenesis, and risk factors associated with BCC.

Conclusions:

The risk of developing BCC depends on both genetic predisposition and exposure to risk. Fair-skinned people account for the overwhelming majority of patients, beyond what would be expected by skin phototype alone. Damage to multiple lines of defense appears to be necessary for cancer development and spread. This damage distorts the concerted effort of deoxyribonucleic acid (DNA) repair, immunosurveillance, and cellular growth regulation to protect against malignant progression. Ultraviolet light exposure is the most critical modifiable factor determining early expression and frequency of BCC development.

Grade 3 anal intraepithelial neoplasia in an HIV-infected African girl

Women with HIV infection are at increased risk of anogenital dysplasia and cancer, related to human papillomavirus infection. These neoplasms are rare in perinatally HIV-infected girls before onset of sexual activity. We report a case of high-grade anal dysplasia in a 10-year-old African girl with untreated perinatal HIV infection.

Keratinocyte apoptosis in epidermal remodeling and clearance of psoriasis induced by UV radiation

Psoriasis is a common chronic skin disorder, but the mechanisms involved in the resolution and clearance of plaques remain poorly defined. We investigated the mechanism of action of UVB, which is highly effective in clearing psoriasis and inducing remission, and tested the hypothesis that apoptosis is a key mechanism. To distinguish bystander effects, equal erythemal doses of two UVB wavelengths were compared following in vivo irradiation of psoriatic plaques; one is clinically effective (311  nm) and one has no therapeutic effect on psoriasis (290  nm). Only 311  nm UVB induced significant apoptosis in lesional epidermis, and most apoptotic cells were keratinocytes. To determine clinical relevance, we created a computational model of psoriatic epidermis. Modeling predicted apoptosis would occur in both stem and transit-amplifying cells to account for plaque clearance; this was confirmed and quantified experimentally. The median rate of keratinocyte apoptosis from onset to cell death was 20  minutes. These data were fed back into the model and demonstrated that the observed level of keratinocyte apoptosis was sufficient to explain UVB-induced plaque resolution. Our human studies combined with a systems biology approach demonstrate that keratinocyte apoptosis is a key mechanism in psoriatic plaques clearance, providing the basis for future molecular investigation and therapeutic development.

Expression of epidermal CAMP changes in parallel with permeability barrier status

Two critical defensive functions of the outer epidermis, the permeability barrier and antimicrobial defense, share certain structural and biochemical features. Moreover, 3antimicrobial peptides (AMP); i.e., mouse beta-defensin 3 (mBD3), mouse cathelicidin protein (mCAMP), and the neuroendocrine peptide, catestatin, all localize to the outer epidermis, and both mBD3 and mCAMP are secreted from epidermal lamellar bodies with other organelle contents that subserve the permeability barrier. These 3 AMP are up-regulated in response to acute permeability barrier disruption, while conversely, mCAMP−/− mice (unable to combatgram-positive pathogens) also display abnormal barrier homeostasis. To determine further whether these two functions are co-regulated, we investigated changes in immunostaining for these 3 AMP in skin samples in which permeability barrier function in mice had been either compromised or enhanced. Compromised or enhanced barrier function correlated with reduced or enhanced immunohistochemical expression of mCAMP, respectively, but conversely with Cst expression likely due to the role of this AMP as an endogenous inhibitor of cathelicidin expression. mBD3 expression correlated with experimental barrier perturbations, but poorly with developmental changes in barrier function. These studies show that changes in cathelicidin and Cst expression parallel changes in permeability barrier status, with a less clear relationship with mBD3 expression.

Infantile haemangiomas: a challenge in paediatric dermatology

Infantile haemangiomas, common benign vascular tumours of childhood, are characterized by rapid growth during the first year of life and a slow regression that is usually completed at 7-10 years of age. These tumours are composed of endothelial cells with high mitotic rates and stromal components such as fibroblasts, mast cells and pericytes. Haemangiomas become a challenge when they are part of a syndrome, are located in certain areas of the body or when complications develop. The above-mentioned factors also influence the treatment modality used. However, although there remain many uncertainties regarding management, the beta-adrenergic receptor blocker propranolol is a promising new candidate for first-line systemic therapy. It produces such a dramatic and rapid response that the appearance of an infantile haemangioma should impart expeditious consideration of the risks and benefits of its use.

Treatment of vulvar intraepithelial neoplasia with topical imiquimod

BACKGROUND

Alternatives to surgery are needed for the treatment of vulvar intraepithelial neoplasia. We investigated the effectiveness of imiquimod 5% cream, a topical immune-response modulator, for the treatment of this condition.

METHODS

Fifty-two patients with grade 2 or 3 vulvar intraepithelial neoplasia were randomly assigned to receive either imiquimod or placebo, applied twice weekly for 16 weeks. The primary outcome was a reduction of more than 25% in lesion size at 20 weeks. Secondary outcomes were histologic regression, clearance of human papillomavirus (HPV) from the lesion, changes in immune cells in the epidermis and dermis of the vulva, relief of symptoms, improvement of quality of life, and durability of response. Reduction in lesion size was classified as complete response (elimination), strong partial response (76 to 99% reduction), weak partial response (26 to 75% reduction), or no response (< or =25% reduction). The follow-up period was 12 months.

RESULTS

Lesion size was reduced by more than 25% at 20 weeks in 21 of the 26 patients (81%) treated with imiquimod and in none of those treated with placebo (P<0.001). Histologic regression was significantly greater in the imiquimod group than in the placebo group (P<0.001). At baseline, 50 patients (96%) tested positive for HPV DNA. HPV cleared from the lesion in 15 patients in the imiquimod group (58%), as compared with 2 in the placebo group (8%) (P<0.001). The number of immune epidermal cells increased significantly and the number of immune dermal cells decreased significantly with imiquimod as compared with placebo. Imiquimod reduced pruritus and pain at 20 weeks (P=0.008 and P=0.004, respectively) and at 12 months (P=0.04 and P=0.02, respectively). The lesion progressed to invasion (to a depth of <1 mm) in 3 of 49 patients (6%) followed for 12 months (2 in the placebo group and 1 in the imiquimod group). Nine patients, all treated with imiquimod, had a complete response at 20 weeks and remained free from disease at 12 months.

CONCLUSIONS

Imiquimod is effective in the treatment of vulvar intraepithelial neoplasia. (Current Controlled Trials number, ISRCTN11290871 [controlled-trials.com].).

Treatment of basal cell carcinoma of the eyelids with 5% topical imiquimod: a 3-year follow-up study

BACKGROUND

The aim of this study was to determine the efficacy and safety of 5% topical imiquimod, and the long-term results following its use, in the treatment of nodular basal cell carcinoma (BCC) of the eyelid.

METHODS

Imiquimod cream (5%) was applied topically to five individuals affected by nodular BCC of the eyelid. The patients were followed up during the 6 weeks of treatment and for another 3 years after treatment. Local side effects and evidence of tumour regression or recurrence were noted.

RESULTS

Complete clinical clearance of the tumour was obtained in four patients, with no response in the fifth patient. Therapy was typically accompanied by significant discomfort due to local side effects, which disappeared following completion of the treatment. None of these patients showed any local recurrence after 3 years.

CONCLUSIONS

Topical imiquimod applied in the form of a 5% cream proved to be a safe, efficacious and sustainable treatment option for nodular BCC of the eyelid in our selected cases.

Antipsoriatic biologic agents for the treatment of atopic dermatitis

Dialogues in Dermatology, a monthly audio program from the American Academy of Dermatology, contains discussions between dermatologists on timely topics. Commentaries from Dialogues Editor-in-Chief Warren R. Heymann, MD, are provided after each discussion as a topic summary and are provided here as a special service to readers of the Journal of the American Academy of Dermatology.

A case of severe eczema following use of imiquimod 5% cream

Imiquimod 5% cream, an immune response modifier licensed for treatment of external ano-genital warts and superficial basal cell carcinomata, is known to cause local erythema, oedema and, rarely, exacerbation of psoriasis. We describe a case of exacerbation of eczema following application of this cream in a man with penile warts.

Wound Healing: An Overview

Understanding wound healing today involves much more than simply stating that there are three phases: inflammation, proliferation, and maturation. Wound healing is a complex series of reactions and interactions among cells and "mediators." Each year, new mediators are discovered and our understanding of inflammatory mediators and cellular interactions grows. This article will attempt to provide a concise overview on wound healing and wound management.

Treatment of multiple lesions of Bowen's disease and squamous cell carcinoma with topical imiquimod

We observed complete clinical and histopathologic remission of papules, plaques and nodules in two patients with multiple lesions of Bowen's disease and squamous cell carcinoma. Our findings indicate that topical imiquimod is a potentially promising therapeutic approach for the local treatment of early forms of cutaneous neoplasia, such as Bowen's disease and squamous cell carcinoma because it is a non-invasive therapy with a good cosmetic outcome. It may therefore be worthy of consideration in a subgroup of patients who cannot have or do not wish to have surgery.