Lentigo maligna (melanoma in situ) treated with imiquimod cream 5%: 12 case reports.

Lentigo maligna (LM) is an in situ variant of melanoma. Although LM has the potential for invasion, it often has a greatly protracted radial growth phase and may remain indolent for years. The current standard of care is surgical excision, but this often results in substantial morbidity; thus, nonsurgical approaches continue to be investigated. Imiquimod cream 5% is an immunomodulatory agent that previously has been reported to successfully eradicate LM. We evaluated the treatment course of topical imiquimod in 12 patients with LM. Data from patients with biopsy-proven LM were collected retrospectively, reviewed, and summarized. Patients ranged in age from 54 to 83 years. Most patients chose imiquimod cream as their initial form of treatment; however, other patients had a history of LM recurrence after excision or had positive histologic margins at the time of excision. Initial application regimens varied from 2 to 7 times weekly. The average duration of treatment was 15.7 weeks but ranged from 7 to 44 weeks. Results of posttreatment biopsies of the most clinically suspicious areas in 6 patients showed histologic clearance; 2 patients demonstrated single atypical melanocytes and 4 patients demonstrated clinical clearance without histologic confirmation. These findings suggest that imiquimod cream 5% may be an effective alternative treatment for LM.

Fatty acids and glucose increase neutral endopeptidase activity in human microvascular endothelial cells.

Neutral endopeptidase (NEP), a membrane-bound metallopeptidase enzyme that degrades neuropeptides, bradykinin, atrial natriuretic factor, enkephalins, and endothelin may regulate response to injury. We have previously demonstrated increased NEP localization and enzyme activity in diabetic wounds and skin compared with normal controls. We hypothesized that hyperlipidemia and hyperglycemia associated with type 2 diabetes mellitus may induce excessive NEP activity and thereby diminish normal response to injury. Human microvascular endothelial cells were treated with five different fatty acids (40 microM) with varying degrees of saturation, including oleic acid, linoleic acid, palmitic acid, stearic acid, and linolenic acid and/or glucose (40 mM) for 48 h. The effect of the antioxidative agents vitamin E and C on NEP enzyme activation was determined by treating the cultured cells with alpha-tocopherol succinate and/or L-ascorbic acid. Cell membrane preparations were assayed for NEP activity by incubation with glutaryl-Ala-Ala-Phe-4-methoxy-beta naphthylamide to generate a fluorescent degradation product methoxy 2 naphthylamine. High glucose or fatty acid concentration upregulated NEP activity. The highest NEP activity was observed with combined elevated glucose, linoleic acid, and oleic acid (P < 0.05). Antioxidant vitamin E and C treatment significantly reduced NEP enzyme activity after fatty acid exposure (P < 0.05). Thus, hyperglycemia and hyperlipidemia associated with type 2 diabetes mellitus may increase endothelial cell NEP activity and thereby decrease early pro-inflammatory responses. The modulator effect of vitamin E and C on NEP membrane enzyme activity after exposure to fatty acid stimulation suggests that lipid oxidation may activate NEP.

Nerve growth factor accelerates wound healing in diabetic mice.

Patients with diabetic neuropathy have reduced numbers of cutaneous nerves, which may contribute to an increased incidence of nonhealing wounds. Nerve growth factor (NGF) has been reported to augment wound closure. We hypothesized that topical 2.5S NGF, a biologically active subunit of the NGF polymer, would accelerate wound repair, augment nerve regeneration, and increase inflammation in excisional wounds in diabetic mice. A full-thickness 6-mm punch biopsy wound was created on the dorsum of C57BL/6J-m+ Leprdb mice (db/db) and heterozygous (db/-) littermates and treated daily with normal saline or 2.5S NGF (1 microg/day or 10 microg/day) on post-injury days 0-6. Time to closure, wound epithelialization, and degree of inflammation were compared using a Student's t-test. Color subtractive-computer-assisted image analysis was used to quantify immunolocalized nerves in wounds. Non-overlapping (20x) digital images of the wound were analyzed for nerve profile counts, area density (number of protein gene product 9.5 positive profiles per unit dermal area) and area fraction (protein gene product 9.5 positive area per unit dermal area). Healing times in db/db mice decreased from 30 days in normal saline-treated mice to 26 days in mice treated with 1 microg/day NGF (p<0.05) and 24 days in mice treated with 10 microg/day NGF (p<0.02). A similar trend in db/- mice was not significant. NGF treatment augmented epithelialization in the db/db mice (p<0.05). Histological evaluation of inflammation in healed wounds showed no statistical difference between treatment groups. Total nerve number, area density, and area fraction were increased in NGF-treated wounds at 14, 21, and 35 days (p<0.05). The 2.5 NGF subunit may improve wound closure kinetics by promoting epithelialization and nerve regeneration. Further studies to determine the role of nerves in wound repair are warranted.

Neutral endopeptidase inhibition in diabetic wound repair.

In response to cutaneous injury, sensory nerves release substance P, a proinflammatory neuropeptide. Substance P stimulates mitogenesis and migration of keratinocytes, fibroblasts, and endothelial cells. Neutral endopeptidase (NEP), a cell surface metallopeptidase, degrades substance P. Chronic nonhealing wounds and skin from patients with diabetes mellitus show increased NEP localization and activity. We hypothesized that increased NEP may retard wound healing and that NEP inhibition would improve closure kinetics in an excisional murine wound model. NEP enzyme activity was measured in skin samples from mutant diabetic mice (db/db) and nondiabetic (db/-) littermates by degradation of glutaryl-ala-ala-phe-4-methoxy-2-naphthylamine. Full-thickness 6-mm dorsal excisional wounds treated with normal saline or the NEP inhibitor thiorphan (10 microM or 25 microM) for 7 days were followed until closure. Histological examination and NEP activity were evaluated in a subset of wounds. NEP activity in unwounded db/db skin (20.6 pmol MNA/hr/ microg) significantly exceeded activity in db/-skin (7.9 pmol MNA/hr/ microg; p = 0.02). In db/db mice, 25 microM thiorphan shortened time to closure (18.0 days; p < 0.05) compared to normal saline (23.5 days). NEP inhibition did not alter closure kinetics in db/-mice. While the inflammatory response appeared enhanced in early wounds treated with thiorphan, blinded histological scoring of healed wounds using a semiquantitative scale showed no difference in inflammation. Unwounded skin from diabetic mice shows increased NEP activity and NEP inhibition improved wound closure kinetics without affecting contraction, suggesting that its principal effect was to augment epithelialization.