Comparison of lesional skin c-KIT mutations with clinical phenotype in patients with mastocytosis.

BACKGROUND: Activating c-KIT mutations cause abnormal mast cell growth and appear to play a role in mastocytosis. However, the correlation of c-KIT mutations with disease phenotypes is poorly characterized. AIM: To evaluate the correlation of c-KIT mutations with clinical presentations and laboratory findings. METHODS: Total cellular RNA was isolated from the skin lesions of 43 adults and 7 children with mastocytosis, and PCR amplicons of cDNA were sequenced for c-KIT mutations. RESULTS: The most common activating mutation, KIT-D816V, was identified in 72% of adults and 57% of children. Additional activating mutations, namely, V560G and the internal tandem duplications (ITDs) 502-503dupAY, were detected in 12% of adults and 8% of children. V560G occurred more commonly in our patients than previously reported, and it appeared to be associated with more advanced disease. Otherwise, the presence or absence of activating mutations did not correlate with skin lesion morphology, disease extent or total serum tryptase levels. Four adults had expression only of wild-type KIT, while two others had expression of a truncated KIT lacking tyrosine kinase activity; yet these patients were clinically indistinguishable from those patients with activating c-KIT mutations. CONCLUSIONS: Activating c-KIT mutations exist in a significant portion of patients with mastocytosis, but not all patients showed expression of these mutations. Except for V560G, the presence or absence of activating c-KIT mutations did not predict the extent of disease. These observations suggest that although activating c-KIT mutations are associated with mast cell growth, other genes probably play a role in the cause of mastocytosis.

Distinct signalling pathways for mutated KIT(V560G) and KIT(D816V) in mastocytosis.

BACKGROUND: The activating mutations KIT(V560G) and KIT(D816V) are associated with mastocytosis. Thus, identifying and inhibiting the signalling pathways associated with mutated KIT gene offers a potentially important strategy for the treatment of mastocytosis. AIM: To correlate KIT mutations with specific signalling pathways in human mast-cell lines using pathway inhibitors. METHODS: Human mast-cell (HMC) lines expressing KIT(V560G) (the cell line HMC-1) and KIT(V560G and D816V) (HMC-1.2) were treated with specific signalling pathway inhibitors for 1-5 days, and the inhibitory effects on growth were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell-proliferation assay, western blotting and flow cytometry. RESULTS: Growth inhibitory assays and western blot analyses showed that the Janus kinase 3/signal transducer and activator of transcription (JAK3/STAT) pathway is the preferential signalling pathway for KIT(V560G), whereas the mechanistic target of rapamycin complex 1/4E-binding protein 1 (mTORC1/4E-BP1) pathway is preferentially linked to KIT(D816V). Inhibition of these critical signalling pathways results in programmed cell death. CONCLUSIONS: KIT(V560G) and KIT(D816V) use different signalling pathways that promote mast-cell growth. Inhibitors of these specific pathways might be effective in treating mastocytosis.

Mutations in the PSTPIP1 gene and aberrant splicing variants in patients with pyoderma gangrenosum.

BACKGROUND: Pyoderma gangrenosum (PG) is a rare, noninfectious form of skin ulceration, typically accompanied by neutrophilic infiltration. Several familial cases have been reported, suggesting the involvement of genetic factors in the aetiology of PG. Two mutations (A230T and E250Q) in the PSTPIP1 gene, encoding proline-serine-threonine phosphatase-interacting protein (PSTPIP)1 have been identified in patients with PAPA (pyogenic sterile arthritis with PG and acne) syndrome, a rare autoinflammatory disorder with autosomal dominant inheritance. AIM: The aim of this study was to sequence PSTPIP1 complementary cDNA and genomic DNA for mutations, and to identify genetic polymorphisms in the promoter region of PSTPIP1 in patients with PG. METHODS: The genomic region and cDNA of the PSTPIP1 gene were sequenced from peripheral blood leucocytes of 14 patients with PG and 20 healthy controls. RESULTS: One patient (PG1) had aberrant splicing variants of the PSTPIP1 transcript with deletions of exons 9, 11 and 12 and of exons 9-12 together, and all other patients with PG carried deletions of exon 11 and of 11-12. We also identified a novel mutation (G258A) in patient PG3, and novel polymorphisms [(CCTG)(6) and (CCTG)(8) tandem repeats] in the promoter region of the PSTPIP1 gene. CONCLUSION: All combinations of aberrant splicing variants had frame shifts and premature stop codons leading to truncated proteins and loss of function of PSTPIP1. The (CCTG)(n) tandem repeats in the promoter region of PSTPIP1 had no association with PG. The mutations G258A and R52Q are predicted by the improved prediction algorithm to have a possibly damaging effect on PSTPIP1 function.

Mastocytosis.

Mastocytosis represents a heterogeneous group of clinical disorders resulting from the infiltration of mast cells in the skin and other organs. Although mastocytosis was first described over 130 years ago, the pathophysiologic mechanisms responsible for this disease have been identified only recently. This article discusses the salient clinical features of the disease, the mechanisms responsible for its development, and provides treatment approaches that have proven useful for managing patients with this disorder.

New insights into the second generation antihistamines.

Second generation antihistamines are recognised as being highly effective treatments for allergy-based disease and are among the most frequently prescribed and safest drugs in the world. However, consideration of the therapeutic index or the benefit/risk ratio of the H1 receptor antagonists is of paramount importance when prescribing this class of compounds as they are used to treat non-life threatening conditions. There are many second generation antihistamines available and at first examination these appear to be comparable in terms of safety and efficacy. However, the newer antihistamines in fact represent a heterogeneous group of compounds, having markedly differing chemical structures, adverse effects, half-life, tissue distribution and metabolism, spectrum of antihistaminic properties, and varying degrees of anti-inflammatory effects. With regard to the latter, there is growing awareness that some of these compounds might represent useful adjunct medications in asthma therapy. In terms of safety issues, the current second generation grouping includes compounds with proven cardiotoxic effects and others with the potential for adverse drug interactions. Moreover, some of the second generation H1 antagonists have given cause for concern regarding their potential to cause a degree of somnolence in some individuals. It can be argued, therefore, that the present second generation grouping is too large and indistinct since this was based primarily on the concept of separating the first generation sedating compounds from nonsedating H1 antagonists. Although it is too early to talk about a third generation grouping of antihistamines, future membership of such a classification could be based on a low volume of distribution coupled with a lack of sedating effects, drug interactions and cardiotoxicity.

B-cell lymphoma in a patient with WHIM syndrome.

WHIM syndrome is a rare congenital familial syndrome consisting of warts, hypogammaglobulinemia, infections, and myelokathexis. We describe a 30-year-old man with WHIM syndrome, in whom red dermal facial nodules developed. The diagnosis of B-cell lymphoma was established with biopsy and immunohistochemical studies. To our knowledge, this is the first reported case of WHIM syndrome complicated by a B-cell lymphoma.

Clobetasol propionate emollient 0.05% in the treatment of atopic dermatitis.

A 4-week, double-blind, randomized clinical trial, comparing the efficacy and safety of clobetasol propionate emollient cream 0.05% and its vehicle, was conducted at four private dermatology clinics in 81 non-hospitalized patients (> or = 12 years old) with moderate-to-severe atopic dermatitis covering 2% or more of their body surface. All patients had at least one lesion 2 cm or more in diameter. Three signs/symptoms of target lesions (erythema, pruritus, and induration/papulation) were scored by investigators on a scale of 0-3 (in 0.5-point increments; 0 = absent, 1 = mild, 2 = moderate, and 3 = severe); the total of the three scores had to be > or = 6 for patients to qualify for study entry. Patients were excluded if they were immunocompromised, pregnant, or nursing; had skin atrophy, telangiectasia or striae in skin areas to be treated; or had received topical treatments for atopic dermatitis within 1 week prestudy, intramuscular triamcinolone within 6 weeks prestudy, or long-term systemic corticosteroid usage within 6 months prestudy. Patients were randomized in a 1:1 ratio to receive either clobetasol propionate emollient 0.05% twice daily (n = 41), or the emollient vehicle twice daily (n = 40), for 4 weeks. A fingertip unit, equaling approximately 0.5 g in males and 0.43 g in females (enough to cover approximately 2% of the body), was used to measure and apply a thin film of study drug to the affected areas. The efficacy was evaluated by investigators and patients on days 4, 8, 15, and 29 after initiation of therapy, and 2 weeks after the end of treatment (day 43). Investigators performed a physician's gross assessment based on the percentage improvement of the target lesion. They also rated changes from baseline in mean severity scores for six individual signs/symptoms (erythema, pruritus, induration/papulation, lichenification, erosion/oozing/crusting, and scaling/dryness) and for total signs/symptoms according to the severity scoring system described above. Patients rated their response to treatment as excellent, good, fair, poor, or worse. Laboratory assessments were made on days 15, 29, and (if necessary) day 43.

Chronic urticaria: pathophysiology and treatment approaches.

Urticaria, a cutaneous reaction pattern, varies clinically and histopathologically. The origin of acute urticaria can be detected in some cases; in patients with chronic urticaria, however, the cause is rarely identified. Thus, most patients with chronic urticaria are considered to have idiopathic disease. The dermal mast cell and its mediators may play a central role in chronic idiopathic urticaria. Other inflammatory cells, including lymphocytes and polymorphonuclear cells, have also been implicated. Treatment is based on identification of the inflammatory cells within skin lesions and blockage of the effects of histamine in the skin. Urticaria in which a lymphocyte-predominant infiltrate is seen often responds to one or more H1 antihistamines. Recently, a new generation of nonsedating or mildly sedating H1 antihistamines has proved useful in the management of these cases. Antihistamine use alone may be unsuccessful in urticaria in which polymorphonuclear neutrophils predominate; frequently, the addition of agents that alter polymorphonuclear neutrophil function, such as colchicine or dapsone, is required. During the introduction of antihistamine and anti-polymorphonuclear neutrophil therapy, a simultaneous brief course of systemic corticosteroid therapy may be necessary, but the extended use of systemic corticosteroids should be avoided because of significant adverse effects. As the pathophysiologic mechanisms responsible for chronic urticaria are better defined, more effective therapeutic agents should become available.

Cetirizine: a new therapeutic alternative for chronic urticaria.

Chronic urticaria represents a cutaneous reaction pattern that may last for slightly more than six weeks to more than five years. Treatment of patients with chronic urticaria can be a problem for both physician and patient because of the significant side effects that may be caused by first-generation H1 antihistamines or long-term corticosteroid therapy. Newer antihistamines represent a major advance for the treatment of patients with chronic urticaria. Of this group, cetirizine appears to offer some distinct pharmacokinetic and pharmacodynamic advantages. An open-label multicenter trial of 217 patients with chronic idiopathic urticaria demonstrated that cetirizine was effective, rapid in onset, and well tolerated. Thus, cetirizine was shown to be an attractive alternative treatment for patients with chronic idiopathic urticaria.

IgG anti-50 kd lymphocyte membrane peptide antibody in patients with Sézary syndrome.

BACKGROUND: Recent evidence suggests that as cutaneous T-cell lymphoma progresses, cell-mediated immunity is reduced and humoral responses are augmented. OBJECTIVE: The present study was designed to compare the IgG response in Sézary syndrome with that in mycosis fungoides. METHODS: The IgG antilymphocyte response was studied in six patients with Sézary syndrome and in 11 patients with mycosis fungoides by means of immunoblot analysis, enzyme-linked immunosorbent assay, immunohistochemistry, and flow cytometry. RESULTS: An IgG antilymphocyte response to a 50 kd peptide was seen in five of the six patients with Sézary syndrome; however, none of the 11 patients with mycosis fungoides expressed this response. CONCLUSIONS: An enhanced IgG immune response to 50 kd lymphocyte peptide may be helpful in identifying disease progression in patients with cutaneous T-cell lymphoma.

Immune-associated cells in basal cell carcinomas of skin.

Increased numbers of mast cells (MCs) and lymphocytes infiltrating in basal cell carcinomas (BCCs) have been observed. The presence of these infiltrating cells has been considered a sign of an immunologic anti-tumor response in the host, but the relationship of these two cell populations has not been examined. To elucidate this possible relationship, 30 non-ulcerated BCCs were analyzed. Frozen sections of the tumors were stained with monoclonal antibodies for Langerhans' cells, lymphocyte subsets and natural killer cells. Fluorescein isothiocynate (FITC)-avidin as well as anti-tryptase and anti-CD45RO monoclonal antibodies were used on formalin-fixed, paraffin-embedded sections for mast cell and T cell identification, respectively. B cells and natural killer cells were rarely observed in these tumors. MCs and T cells were quantified by direct enumeration and expressed as number of cells per high power field (hpf). FITC-avidin and anti-tryptase antibodies were equivalent in their ability to identify MCs. MC content in BCCs ranged from 1.0 to 31 cells/hpf. The number of T cells ranged from 0 to 50 cells/hpf with helper/suppressor cell ratios of 0.2 to 10. There was no correlation between helper/suppressor ratios and mast cell numbers; however, an inverse relationship was observed between the numbers of T cells and the number of mast cells in these tumors. These studies indicate that T cells and MCs are the primary immune cell populations responding to BCCs, and that decreased numbers of T cells are associated with more aggressive tumors.

A comparison of twice-daily and once-daily administration of fluticasone propionate cream, 0.05%, in the treatment of eczema.

This multicenter, double-blind, randomized, parallel, four-week, vehicle-controlled study compared the efficacy and safety of once- and twice-daily application of fluticasone propionate cream, 0.05%, over a twenty-eight-day treatment period in 238 patients with moderate-to-severe eczema. Clinical evaluations, which included the physician's gross assessment, the severity of signs and symptoms, and the patient's subjective evaluation, were conducted at baseline and at weekly intervals following initiation of treatment. Both fluticasone QD and BID were found to be superior to vehicle at each evaluation. Application of fluticasone BID was found to be superior to once-daily application at day 22 based on the physician's gross assessment, and at days 15 and 22 based on the patient's subjective assessment. There were, however, no statistically significant differences between QD and BID application at day 8 and at the end of the twenty-eight-day treatment period. The results of this study suggest that QD application may be recommended for the treatment of moderate-to-severe eczema in most patients. As always, treatment effectiveness should be monitored periodically and BID application may be necessary to maximize therapeutic benefits in some patients.

Cetirizine and astemizole therapy for chronic idiopathic urticaria: a double-blind, placebo-controlled, comparative trial.

BACKGROUND: Cetirizine and astemizole have been shown to be safe and effective in the treatment of patients with chronic idiopathic urticaria. Cetirizine brings about clinical benefit more rapidly. OBJECTIVE: The purpose of this study was to compare the efficacy of single daily doses of cetirizine and astemizole in relieving the symptoms of chronic idiopathic urticaria, with particular emphasis on the commencement of action. METHODS: Patients with chronic idiopathic urticaria were randomly assigned to relieve either 10 mg of cetirizine, 10 mg of astemizole, or placebo for 4 weeks in a multicenter double-blind trial. Patients rated symptom severity each night, and investigators rated symptoms weekly. RESULTS: One hundred eighty-seven patients were enrolled in the trial; 180 were included in the safety analysis and 177 were included in at least one efficacy analysis. Both cetirizine and astemizole were significantly superior to placebo in relieving symptoms of chronic idiopathic urticaria. Both patients' and investigators' ratings indicated that cetirizine acted more rapidly. Both active treatments were well tolerated, and the incidence of somnolence did not differ statistically between cetirizine (14.5%) and astemizole (10.3%). CONCLUSION: Both cetirizine and astemizole provide effective relief of the symptoms of chronic idiopathic urticaria with similar side-effect profiles. However, clinical benefit occurs significantly more rapidly with cetirizine.

Rat mast cell protease I alters cell metabolism.

Rat connective tissue mast cells are known to store significant amounts of mast cell protease I (RMCP I), which suppresses normal cell growth and mediates cytotoxicity against tumor cell lines, including the fibrosarcoma cell line FL. To better define its effects on FL cells, RMCP I was added to FL cultures for 30 min. Analysis of de novo nuclear protein synthesis revealed that RMCP I suppressed the expression of three proteins (41, 46, and 69 kD) and enhanced the expression of two other proteins (25 and 32 kD). Treatment of FL cells with diisopropylfluorophosphate (DFP)-inactivated RMCP I proved that these effects were largely independent of the protease catalytic site. Western blot hybridization, using a monoclonal antibody to phosphotyrosine-containing proteins, revealed that RMCP I inhibited phosphorylation of a nuclear and a cytoplasmic 81-kD tyrosylprotein. Inhibition of nuclear tyrosine kinase activity by RMCP I appeared to be catalytic site dependent, whereas cytoplasmic tyrosine kinase inhibition was independent of RMCP I proteolytic activity. Biotinylated RMCP I was used to identify potential surface-binding proteins. Three specific binding complexes (130, 150, and 210 kD) were detected. The binding of biotinylated RMCP I to these surface proteins was inhibited by excess unlabeled RMCP I, but not by trypsin or chymotrypsin. We speculate that the binding proteins may be critical in initiating RMCP I-induced metabolic changes on FL cells. The ability of RMCP I to alter the metabolism of cells suggests that it may have an important role in regulating their functions.