R. St. C. Barnetson

Inflammation is associated with progression of actinic keratoses to squamous cell carcinomas in humans

Summary Background Squamous cell carcinoma (SCC) is a common skin tumour that may metastasize and lead to death. We have observed that before actinic keratoses (AK) progress to SCCs they may become tender and inflamed. In some of these, histological examination shows that they are, in fact, SCCs.

Imiquimod‐induced regression of actinic keratosis is associated with infiltration by T lymphocytes and dendritic cells: a randomized controlled trial

Background  Imiquimod 5% cream is a topically applied immune response modifier that has been shown to give effective treatment of actinic keratosis (AK). The therapeutic effects of imiquimod are likely to involve the provocation of a cutaneous immune response against abnormal cells, an assumption based on a strong correlation between complete clearance rates and the severity of the local skin reactions (erythema, oedema, erosion/ulceration, weeping/exudation and scabbing/crusting); however, no clinical studies have conclusively proved this mechanism.

Squamous cell carcinoma growth in mice and in culture is regulated by c-Jun and its control of matrix metalloproteinase-2 and -9 expression

Squamous cell carcinoma (SCC) is an invasive malignancy of epidermal keratinocytes. Surgical excision is currently the main treatment; however, this can cause scarring and disfigurement. There is accordingly, an acute need for alternative strategies to treat SCC. The transcription factor c-Jun is expressed in human SCC and another common form of invasive skin cancer, basal cell carcinoma together with the mitogenic marker-proliferating cell nuclear antigen. Here, we have employed DNAzymes (catalytic DNA molecules) targeting c-Jun (Dz13) to inhibit c-Jun expression in SCC cells. Dz13 inhibits SCC proliferation and suppresses solid SCC tumor growth and tumor angiogenesis in severe combined immunodeficient mice. We further demonstrate that Dz13 inhibits c-Jun, together with matrix metalloproteinase (MMP)-2 and MMP-9 expression in the tumors, consistent with DNAzyme inhibition of MMP-2 and MMP-9 gelatinolytic activity by zymography. Dz13 also suppressed the expression of vascular endothelial growth factor and fibroblast growth factor-2 in the tumors. These findings demonstrate that c-Jun regulates SCC growth and suggest that DNAzymes targeting this transcription factor may potentially be useful as inhibitors of cutaneous carcinoma.

Imiquimod induced regression of clinically diagnosed superficial basal cell carcinoma is associated with early infiltration by CD4 T cells and dendritic cells

Imiquimod is presumed to clear basal cell carcinoma (BCC) through apoptosis mediated by cytokines and lymphocytes, with erosion often observed correlating with complete clearance. The objective was to determine the cellular immune response early in the course of treatment in order to examine whether cell mediated immunity could be responsible for imiquimod mediated regression of BCC. Sixteen adults with clinically diagnosed BCC were openly assigned to 5 days per week of drug (1, 2 or 4 weeks) or placebo (2 weeks) in groups of four. No baseline biopsy was performed. Post‐treatment excision specimens were examined by routine and immunohistochemical staining. Treatment was associated with the early appearance of CD4 cells, activated dendritic cells and macrophages, with later infiltration by CD8 T cells. Dendritic cells continually increased with time, while macrophages reached a maximum at 1 week and then declined slightly. There were comparatively few neutrophils or γδ T cells. Early infiltrates were most prominent in the tumour and upper dermis. The results are consistent with a cell mediated immune response being responsible for the clearance of the BCC. Several immune‐mediated tumour destruction mechanisms are likely to be involved.

Mechanisms in cutaneous drug hypersensitivity reactions

Up to 3% of all hospital admissions are due to adverse drug reactions (ADRs), and between 10% and 20% of hospital inpatients develop ADRs. Individual susceptibility to becoming ‘sensitized’ or allergic to a drug is thought to result from altered metabolic handling of the drug. Reactive intermediate compounds form haptens, bind to proteins and induce immune responses. Depending on whether the immune system generates antibodies or sensitized T cells, different clinical patterns of hypersensitivity may result. At present, both in vivo or in vitro tests to identify the culprit drug or to confirm the presence of hypersensitivity are not widely used because they are either not generally robust or not readily accessible. In vitro tests require the true immunogen/antigen to detect antibodies or sensitized T cells. As the metabolic basis underlying susceptibility to adverse drug reactions is elucidated, the resolution of immunological mechanisms and development of reliable tests will ensue. This will also become of great value for prediction of individuals at risk of becoming sensitized by a particular drug.

Clinical response of dermatitis herpetiformis skin lesions to a gluten-free diet

Patients with dermatitis herpetiformis have been studied prospectively for 2 years to assess the effect of a gluten‐free diet (GFD) on control of the skin lesions. Daily requirements for oral medication with sulphapyridine or dapsone were reduced by GFD treatment and if complete clinical remission of the skin disease occurred, it was maintained while the diet was strictly observed. However, complete remission did not occur significantly more often in GFD‐treated patients than in patients taking a normal diet. Many of the latter group exhibited variation in their drug dose requirements during the period of study.

A novel technique for the examination of skin biopsies by laser capture microdissection

Background:  Skin is an inherently heterogeneous tissue, thus the procurement of pure cell populations is critical for the accurate correlation of a molecular profile to a particular cell type or histological location. Laser Capture Microdissection (LCM) permits the efficent procurement of cells and mapping of genetic changes from histologically prepared samples.

Increased Fas ligand expression by T cells and tumour cells in the progression of actinic keratosis to squamous cell carcinoma

Background  In the counterattack model of tumorigenesis, it has been proposed that tumours develop resistance to attack from Fas ligand (FasL)‐expressing cytotoxic T cells by downregulating Fas (immune escape), while at the same time upregulating FasL expression to induce apoptosis in Fas‐expressing T cells (counterattack).

Modulation of Ia+ Langerhans cell numbers in vivo by cultured epidermis derived supernatants and by GM-CSF

Abstract This paper demonstrates that epidermal cells in culture produce an activity which can increase the frequency of Ia+ epidermal Langerhans cells (LC). This was achieved by treating mice topically with a mixture containing supernatant derived from primary culture of murine epidermis (ES) and a synthetic corticosteroid, triamcinolone acetonide (TAG). The presence of the supernatant in the mixture partially protected the Ia+ LC from depletion by the steroid. The Ia+ LC frequency increasing activity was measured as the difference between the Ia+ LC frequency due to treatment with steroid mixed with supernatant and the Ia+ LC frequency due to treatment with steroid mixed with negative control medium. The mean frequency of Ia+ LC in epidermis treated with TAC mixed with ES was 606(SD 43) cells/mm2, as compared with 486 (SD 68) cells/mm2 in the epidermis treated with TAC mixed with control medium. The activity appeared to be caused by (a) proteinaceous factor(s). A fraction of ES which was retained above a ≥10 KDa molecular weight cut‐off membrane was capable of partially protecting Ia+ LC frequency from TAC depletion. Supernatants from cultured lymph nodes, dermis as well as the squamous cell carcinoma lines T7 and T79, but not the human osteosarcoma cell‐line 143B, also contained similar activities. We demonstrate that GM‐CSF also increased the number of Ia+ epidermal LC when applied topically to mouse skin in this system. Therefore, using this Ia+ LC frequency modulation system, we propose that GM‐CSF is one example of a cytokine which may be involved in the regulation of Ia+ LC numbers in epidermis and that epidermal cells produce factors which can increase the number of Ia+ LC.

Evaluation of 0.75% metronidazole gel in acne : a double-blind study

Metronidazole, an imldazole, is an antibiotic with established efficacy against anaerobic bacteria. To date, however, there are no published data concerning the efficacy of topical metronidazole in the treatment of acne. This randomized, double‐blind prospective clinical study of 96 patients was performed to investigate the efficacy and tolerability of 0.75% metronidazole gel vs. placebo in the treatment of mild to moderate acne. The results of this study showed no significant benefit in using 0.75% metronidazole gel over placebo in reducing counts of inflamed and non‐inflamed lesions of acne. There was also no statistically significant difference between the two groups at any stage in the trial when skin tolerability was assessed.