Mast Cells in Human Cutaneous Neurofibromas: Density, Subtypes, and Association with Clinical Features in Neurofibromatosis 1

Background: Cutaneous neurofibromas (cNFs) are hallmarks of neurofibromatosis 1 (NF1) and cause the main disease burden in adults with NF1. Mast cells are a known component of cNFs. However, no comprehensive characterization of mast cells in cNFs is available, and their contributions to cNF growth and symptoms such as itch are not known.Methods: We collected 60 cNFs from ten individuals with NF1, studied their mast cell proteinase content, and compared the mast cell numbers to selected clinical features of the tumors and patients. The tumors were immunolabeled for the mast cell markers CD117, tryptase, and chymase, and the percentage of immunopositive cells was determined using computer-assisted methods.Results: The median proportions of positive cells were 5.5% (range 0.1-14.4) for CD117, 4.0% (1.2-7.0) for tryptase, and 5.0% (1.1-15.9) for chymase. The median densities of cells immunopositive for CD117, tryptase, and chymase were 280, 243, and 250 cells/mm2, respectively. Small tumors, growing tumors, and tumors from patients below the median age of 33 years displayed a high proportion of mast cells. Cells expressing both tryptase and chymase were the predominant mast cell type in cNFs, followed by cells expressing chymase only.Conclusion: The results highlight the abundance of mast cells in cNFs and that their number and subtypes clearly differ from those previously reported in unaffected skin.</p

Cervical squamous carcinoma cells are resistant to the combined action of tumor necrosis factor-α and histamine whereas normal keratinocytes undergo cytolysis

<p>Abstract</p> <p>Background</p> <p>Previous reports showed that mast cells can typically be found in the peritumoral stroma of cervix carcinomas as well as in many other cancers. Both histamine and TNF-α are potent preformed mast cell mediators and they can act simultaneously after release from mast cells. Thus, the effect of TNF-α and histamine on cervical carcinoma cell lines was studied.</p> <p>Methods and results</p> <p>TNF-α alone induced slight growth inhibition and cell cycle arrest at G0/G1 phase in SiHa cells, but increased their migration. Histamine alone had no effect on cells. In addition, TNF-α and histamine in combination showed no additional effect over that by TNF-α alone, although SiHa cells were even pretreated with a protein synthesis inhibitor. Furthermore, TNF-α-sensitive ME-180 carcinoma cells were also resistant to the combination effect of TNF-α and histamine. In comparison, TNF-α or histamine alone induced growth inhibition in a non-cytolytic manner in normal keratinocytes, an effect that was further enhanced to cell cytolysis when both mediators acted in combination. Keratinocytes displayed strong TNF receptor (TNFR) I and II immunoreactivity, whereas SiHa and ME-180 cells did not. Furthermore, cervix carcinoma specimens revealed TNF-α immunoreactivity in peritumoral cells and carcinoma cells. However, the immunoreactivity of both TNFRs was less intense in carcinoma cells than that in epithelial cells in cervical specimens with non-specific inflammatory changes.</p> <p>Conclusion</p> <p>SiHa and ME-180 cells are resistant to the cytolytic effect of TNF-α and histamine whereas normal keratinocytes undergo cytolysis, possibly due to the smaller amount of TNFRs in SiHa and ME-180 cells. In the cervix carcinoma, the malignant cells may resist this endogenous cytolytic action and TNF-α could even enhance carcinoma cell migration.</p

Pinoresinol stimulates keratinocyte proliferation and downregulates TNF‐α secretion in peripheral blood mononuclear cells: An experimental in vitro study

Abstract Background and Aims Natural coniferous resins are used in traditional medicine for the treatment of skin wounds. Coniferous wood resins (“callus” resin) are a mixture of abietic (resin) acids, lignans such as pinoresinol, and p‐coumaric acid. The wound‐healing properties of resins are thought to be related to their antimicrobial properties, but also to their effects on cell proliferation and inflammation. The purpose of this study was to identify and investigate the effects of novel aqueous dispersions of resin and its main components in the proliferation of human primary keratinocytes in vitro and in the expression of proinflammatory cytokines in human peripheral blood mononuclear cells. Methods The proliferation studies were performed under low and high calcium conditions with or without added growth stimulators at the time points of 2 and 6 days using AlamarBlue Cell Viability Reagent. The cytokine release assay was carried out by incubating the cells with the test articles for 18 h, after which the levels of tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), IL‐6, and IL‐8 were measured in the supernatant by enzyme‐linked immunosorbent assay. Results Resin and the purified lignan PINO, but not p‐coumaric acid or abietic acid (industrial tall oil rosin), enhanced the proliferation of human keratinocytes in vitro and inhibited the expression of TNF‐α, and to a lesser extent the expression of IL‐1β in peripheral blood mononuclear cells. Conclusions In this study, novel aqueous dispersions of spruce resin were used to investigate the effects of main resin components on keratinocyte proliferation and on the expression of key proinflammatory cytokines known to be associated with chronic wounds. The observations suggest that lignans, such as PINO, but not resin acids, are the components of resins that mediate the proliferative and TNF‐α‐suppressing effects. Lignans including PINO were identified as novel potential compounds in the treatment of chronic skin ulcers

Spectrum of malignant and premalignant skin lesions in 505 adult subjects at risk of skin cancers

Abstract Patients at risk of skin cancers can develop varying types of cutaneous malignancies. However, some subjects may develop only one type of lesion. In this cross-sectional study, the spectrum of premalignant (PM) and malignant skin lesions and their risk factors were studied. Therefore, 505 adult subjects (aged 21–79 years, 256 males and 249 females, 96 with immunosuppression) at risk of any type of skin cancer were examined for cutaneous malignancies, nevi, actinic keratoses, photodamage, and possible risk factors. First, 12 different groups were identified with a varying set of PM and/or malignant skin lesions. Next, 5 larger groups were formed from them: basal cell carcinoma (BCC) only, malignant melanoma (MM) only, squamous cell carcinoma (SCC) and/or PM, BCC + SCC and/or PM, and MM + keratinocyte carcinoma (KC) and/or PM. The groups with BCC or MM only were younger and showed less photodamage than the mixed groups, while SCC/PM showed similarity with them. In logistic regression analyses, the platelet-to-lymphocyte ratio was associated with an increased risk of concomitant KC (OR 1.028, p = 0.023) or SCC/PM (OR 1.009, p = 0.047) in subjects with MM or BCC, respectively. Actinic keratoses produced ORs 0.246–0.252 (p = 0.008–0.020) for BCC in subjects with SCC/PM. Interestingly, atypical mole syndrome decreased the risk of SCC/PM in subjects with BCC (OR 0.092, p = 0.001). Advanced age was a significant risk factor for an additional type of lesion in all 3 comparisons (ORs 1.088–1.388, p = 0.001). In conclusion, even though there are numerous patients with only one lesion type, advancing age may determine the final lesion multiplicity

Sequential Increase in Complement Factor I, iC3b, and Cells Expressing CD11b or CD14 in Cutaneous Vasculitis

Mast cells contribute to the pathogenesis of cutaneous vasculitis through complement C3 that is cleaved to C3b and then to iC3b by complement factor I. The receptor of iC3b, CD11b, is expressed on neutrophils and monocytes and CD14 on monocytes. Their role in vasculitis is obscure. In this study, frozen skin biopsies from the nonlesional skin, initial petechial lesion, and palpable purpura lesion from 10 patients with immunocomplex-mediated small vessel vasculitis were studied immunohistochemically for complement factor I, iC3b, CD11b, and CD14. Peripheral blood mononuclear cells from 5 healthy subjects were used to study cell migration and cytokine secretion. Already, the nonlesional skin revealed marked immunostaining of complement factor I, iC3b, CD11b, and CD14, and their expression increased sequentially in initial petechial and palpable purpura lesions. Mast cell C3c correlated to iC3b, and both of them correlated to CD11b+ and CD14+ cells, in the nonlesional skin. The stimulation of mononuclear cells with 0.01-0.1 μg/ml iC3b induced cell migration in the transwell assay. C3a stimulated slightly interleukin-8 secretion, whereas 1 μg/ml iC3b inhibited it slightly, in 4/5 subjects. In conclusion, the C3-C3b-iC3b axis is activated already in the early vasculitis lesion leading to progressive accumulation of CD11b+ and CD14+ cells