Increased expression of complement C3c, iC3b, and cells containing CD11b or CD14 in experimentally induced psoriatic lesion.

Psoriasis is a chronic inflammatory skin disease with a characteristic isomorphic reaction, i.e. the Köbner reaction, induced by slight epidermal trauma. In this study, the tape-stripping technique was used to induce the development of Köbner reaction in 18 subjects with psoriasis. Eight subjects developed a positive reaction. To study the early cellular changes, skin biopsies were taken at the baseline and subsequent time points of 2 h, 1 d, 3 d, and 7 d for the immunostaining of complement C3c, iC3b, and cells expressing complement receptor 3 (CD11b/CD18; a receptor of iC3b) or CD14. The results show that the positive Köbner reaction is associated with rapid (2 h-1 d) and sustained (3-7 d) increase in the expression of epidermal C3c and iC3b and dermal C3c. In addition, there was a positive correlation between CD11b+ and CD14+ cells in baseline and 2 h-1 d biopsies with a subsequent increase in CD11b+ and CD14+ cells in 3-7 d biopsies in the Köbner-positive group. In the Köbner-negative group, only a transient increase in epidermal iC3b at 2 h-1 d, as well as rapid (2 h-1 d) and sustained increase (3-7 d) in dermal iC3b and CD14+ cells, was observed. In experiments with cultured monolayer keratinocytes, a slight cell damage already at 30 mJ/cm2 ultraviolet B irradiation led to increased expression of C3c, but not iC3b. Therefore, there are marked differences between Köbner groups in respect to the expression of C3c, iC3b, and cells expressing CD11b or CD14. Of note is the rapid and sustained increase in epidermal C3c and iC3b in the positive Köbner reaction.

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

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.

FoxP3-Positive Cells and Their Contacts with Mast Cells Are Highly Increased in Basal Cell Carcinoma.

INTRODUCTION: The cells of the immune system are thought to contribute to the development of skin cancers, such as basal cell carcinoma (BCC). One possible mechanism may be the interaction between mast cells and regulatory T cells (Tregs), resulting in immunosuppression. METHODS: Fresh-frozen biopsies from the lesional and nonlesional skin of 16 patients with BCC were processed for the enzymehistochemical staining of mast cell tryptase, immunohistochemical staining of FoxP3 (a marker of Tregs) as well as for the double-staining method to label tryptase+ cells and FoxP3+ cells on the same cryosection. The cell numbers and apparent morphological contacts (AMCs) between these cell types were counted. RESULTS: There was a high increase in the number of tryptase+ cells, FoxP3+ cells, and AMCs between them in the lesional compared to corresponding nonlesional skin (p < 0.0001) in all cases. CONCLUSION: A morphological basis is theoretically present in BCC, suggesting an immune evasive microenvironment.

Corticotropin-releasing hormone receptor-1 is increased in mast cells in psoriasis and actinic keratosis, but not markedly in keratinocyte skin carcinomas.

Corticotropin-releasing hormone receptor-1 (CRH-R1) is expressed in human mast cells, but its role in skin diseases is unknown. By using a sequential double-staining technique, the mast cell expression of CRH-R1 was investigated in biopsies from lesional and non-lesional skin samples of patients with actinic keratosis (AK), basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and psoriasis. Dermal tryptase+ mast cells expressed CRH-R1 immunoreactivity in the non-lesional skin in all patient groups. The CRH-R1 expression was significantly increased in the lesional skin of AK (p = 0.03) and psoriasis (p = 0.02), non-significantly in BCC (p = 0.129), but not increased in SCC. To investigate the regulation of CRH-R1, the LAD2 mast cell line was irradiated with UVB or stimulated with CRH or 1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3 ]. Consequently, UVB at 90 mJ/cm2 (p = 0.041) and 120 mJ/cm2 (p = 0.039) decreased CRH-R1 expression. Instead, CRH at 100 and 1000 nM increased CRH-R1 immunostaining, but did not affect the proliferative response. The treatment with 10 and 100 nM 1,25-(OH)2 D3 led to a noticeable increase in CRH-R1 staining. After irradiating with UVB, the concentration of CRH increased in the conditioned medium, but not in sonicated LAD2 mast cells. In conclusion, the lack of sufficient levels of CRH-R1 in mast cells may be related to diminished antitumoural response in SCC and possibly in BCC.

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.

Mast cell-neural interactions contribute to pain and itch.

Mast cells are best recognized for their role in allergy and anaphylaxis, but increasing evidence supports their role in neurogenic inflammation leading to pain and itch. Mast cells act as a "power house" by releasing algogenic and pruritogenic mediators, which initiate a reciprocal communication with specific nociceptors on sensory nerve fibers. Consequently, nerve fibers release inflammatory and vasoactive neuropeptides, which in turn activate mast cells in a feedback mechanism, thus promoting a vicious cycle of mast cell and nociceptor activation leading to neurogenic inflammation and pain/pruritus. Mechanisms underlying mast cell differentiation, activation, and intercellular interactions with inflammatory, vascular, and neural systems are deeply influenced by their microenvironment, imparting enormous heterogeneity and complexity in understanding their contribution to pain and pruritus. Neurogenic inflammation is central to both pain and pruritus, but specific mediators released by mast cells to promote this process may vary depending upon their location, stimuli, underlying pathology, gender, and species. Therefore, in this review, we present the contribution of mast cells in pathological conditions, including distressing pruritus exacerbated by psychologic stress and experienced by the majority of patients with psoriasis and atopic dermatitis and in different pain syndromes due to mastocytosis, sickle cell disease, and cancer.

High regional mortality due to malignant melanoma in Eastern Finland may be explained by the increase in aggressive melanoma types.

BACKGROUND: A regional skin cancer prevention program in Eastern Finland revealed a relatively high age-standardized mortality due to malignant melanoma during 2013-2017. An explanation for this is needed. PURPOSE: To analyse the 543 melanoma samples in 524 subjects collected during 2000-2013 at Kuopio University Hospital and reposited in the Biobank of Eastern Finland. A focus was directed to factors related to metastasis. METHODS: The samples were analysed anonymously by examining the histopathological report, referral text and the list of diagnoses. A possible state of immunosuppression was evaluated. RESULTS: The mean age at the diagnosis of malignant melanoma (MM), lentigo maligna (LM) and melanoma in situ was relatively high, i.e., 66.2, 72.1 and 63.3, respectively. Especially the MM type increased markedly during 2000-2013. In further analyses of a representative cohort of 337 samples, the proportion of nodular melanoma and LM/LMM melanoma was relatively high, 35.6 and 22.0%, respectively, but that from superficial spreading melanoma relatively low (33.8%). Metastasis correlated with immunosuppression, male gender, Clark level, Breslow thickness, ulceration, mitosis count, invasion into vessels and/or perineural area, microsatellites, melanoma subtype, body site, recidivism, and the absence of dysplastic nevus cells. CONCLUSION: The marked increase in aggressive melanomas with associated metastasis, and the relatively high age at diagnosis, can partially explain the mortality.

Association of Elevated Serum Tryptase with Cutaneous Photodamage and Skin Cancers.

INTRODUCTION: Mast cells and their major protein, the serine proteinase tryptase, can be involved in cutaneous photodamage and carcinogenesis. The serum test of tryptase (S-tryptase) measures total tryptase protein (active tryptase and inactive protryptases), and S-tryptase is elevated in a variety of diseases, for example, in mastocytosis and α-tryptasemia. OBJECTIVES: The objective of this study is to study whether S-tryptase is a marker of cutaneous photodamage and carcinogenesis. METHODS: Adult subjects (n = 399, aged 21-79) evaluated to be at risk for skin cancers were recruited at the dermatological policlinic and examined for photodamage severity, mole count, actinic keratoses (AKs), skin cancers, and immunosuppression (IS). A blood sample was analyzed for S-tryptase using the ImmunoCAP® Tryptase fluoroenzymeimmunoassay. RESULTS: There was no difference in S-tryptase between non-IS (n = 321) and IS (n = 78) subjects or between genders. S-tryptase correlated slightly to photodamage and AKs in 321 non-IS subjects, and this association can be related, in part, to the age of subjects. In 34 subjects, S-tryptase was elevated (≥13.5 ng/mL), and in 20 males, but not in 14 females, the photodamage level was significantly (p = 0.031) more severe than in 179 males with normal S-tryptase. In contrast, there were more frequently subjects (n = 12) with past or present skin cancer (basal or squamous cell carcinoma or melanoma) in 14 females with elevated S-tryptase than in 186 female controls. So far, no explanation has been found for the elevated S-tryptase. CONCLUSION: There are significant associations between elevated S-tryptase and skin carcinogenesis, but the molecular mechanisms are unclear and gender differences can exist.

Mast Cells Are a Marked Source for Complement C3 Products That Associate with Increased CD11b-Positive Cells in Keratinocyte Skin Carcinomas.

By using immunohistochemistry and antibodies that identify complement C3c (in C3 and C3b) or CD11b receptor, we report that the proportion C3c+ mast cells and the number of CD11b+ cells are increased in basal cell carcinoma (BCC). Instead, only CD11b+ cells are increased in squamous cell carcinoma/Bowen's disease, and only slightly so in actinic keratosis. Only C3c+ mast cells are increased in psoriasis. Furthermore, C3c+ mast cells correlated positively with CD11b+ cells, and iC3b immunoreactivity was detected around tryptase+ mast cells. Therefore, mast cells may convey immunoregulatory signals through C3, C3b, and iC3b to CD11b+ cells, especially in BCC.

CD40 Ligand Is Increased in Mast Cells in Psoriasis and Actinic Keratosis but Less So in Epithelial Skin Carcinomas.

The expression of CD40 ligand (CD40L) in mast cells was investigated in biopsies from lesional and non-lesional skin samples of patients with psoriasis, actinic keratosis (AK), basal cell carcinoma, and squamous cell carcinoma using a sequential double-staining technique. The percentage of CD40L+ mast cells was higher in the lesional than in the non-lesional skin (p < .003). Interestingly, this percentage was lower in both carcinomas than in psoriasis and actinic keratosis (p < .025). Cells immunopositive for CD40 receptor were increased in all lesion types but especially so in carcinomas. The results suggest a dysregulated anti-tumoral immune response by mast cell CD40L in skin carcinomas.

Decrease in chymase activity is associated with increase in IL-6 expression in mast cells in atopic dermatitis.

Mast cell chymase and interleukin (IL)-6 can be involved in atopic dermatitis and chymase can degrade IL-6. Our aim was therefore to study the expression of mast cell chymase and IL-6 in atopic skin using enzyme- and immunohistochemistry and to analyse their interaction in vitro. Chymase activity was significantly reduced in mast cells in skin lesions whereas the percentage of IL-6(+) mast cells was increased. Low recombinant human (rh)-chymase concentration (10-100 ng/ml) stimulated and higher concentration (1,000 ng/ml) inhibited the proliferation of T cells and peripheral blood mononuclear cells. Rh-IL-6 inhibited T-cell proliferation, and even inhibited the proliferation induced by rh-chymase. Pretreatment of rh-IL-6 with a high rh-chymase concentration prevented the IL-6-induced inhibition in T-cell proliferation. The results suggest that reduction in chymase activity can give rise to increased cellular effects of mast cell IL-6 and that chymase and IL-6 can modify each other's effects.

Experimentally induced psoriatic lesions associate with rapid but transient decrease in interleukin-33 immunostaining in epidermis.

A slight epidermal damage can induce the Köbner reaction in psoriasis, and the "alarmin", interleukin-33 (IL-33), may be involved in this process. Therefore, the uninvolved psoriatic skin was tape-stripped, and skin biopsies were collected at 0 day, 2 h and 3 days or at 0 day, 1 day and 7 days for immunohistochemistry. Eight patients out of 18 with the positive Köbner reaction showed a decrease in epidermal thickness and revealed transient reduction in epidermal nuclear immunostaining of IL-33 in 2-h, 1-day, 3-day biopsies compared to the 10 Köbner-negative patients. In keratinocyte cultures, the full-length 32-kDa IL-33 was detected after damaging the cells with freeze-thawing. Interestingly, a very low concentration of rh-IL-33 (0.001­0.01 ng/ml) significantly stimulated (3)H-thymidine uptake by human LAD2 mast cells, but not by psoriatic peripheral blood mononuclear cells. The results show that epidermal IL-33 associates with positive Köbner response, and only a small amount of the IL-33 apparently released may induce proliferation in dermal mast cells.

Molecular targets on mast cells and basophils for novel therapies.

Mast cells and basophils (MCs/Bs) play a crucial role in type I allergy, as well as in innate and adaptive immune responses. These cells mediate their actions through soluble mediators, some of which are targeted therapeutically by, for example, H1- and H2-antihistamines or cysteinyl leukotriene receptor antagonists. Recently, considerable progress has been made in developing new drugs that target additional MC/B mediators or receptors, such as serine proteinases, histamine 4-receptor, 5-lipoxygenase-activating protein, 15-lipoxygenase-1, prostaglandin D2, and proinflammatory cytokines. Mediator production can be abrogated by the use of inhibitors directed against key intracellular enzymes, some of which have been used in clinical trials (eg, inhibitors of spleen tyrosine kinase, phosphatidylinositol 3-kinase, Bruton tyrosine kinase, and the protein tyrosine kinase KIT). Reduced MC/B function can also be achieved by enhancing Src homology 2 domain-containing inositol 5' phosphatase 1 activity or by blocking sphingosine-1-phosphate. Therapeutic interventions in mast cell-associated diseases potentially include drugs that either block ion channels and adhesion molecules or antagonize antiapoptotic effects on B-cell lymphoma 2 family members. MCs/Bs express high-affinity IgE receptors, and blocking their interactions with IgE has been a prime goal in antiallergic therapy. Surface-activating receptors, such as CD48 and thymic stromal lymphopoietin receptors, as well as inhibitory receptors, such as CD300a, FcγRIIb, and endocannabinoid receptors, hold promising therapeutic possibilities based on preclinical studies. The inhibition of activating receptors might help prevent allergic reactions from developing, although most of the candidate drugs are not sufficiently cell specific. In this review recent advances in the development of novel therapeutics toward different molecules of MCs/Bs are presented.

Increased numbers of tryptase-positive mast cells in the healthy and sun-protected skin of tobacco smokers.

BACKGROUND: Tobacco smoking may cause skin aging through mast cell proteinases. OBJECTIVE: To compare the numbers of mast cells showing tryptase and chymase in the healthy-looking skin of smokers and non-smokers. METHODS: The study subjects consisted of 80 males, 42 of whom were smokers and 38 non-smokers. A skin biopsy from the medial arm was processed for immunohistochemical staining of tryptase and chymase, as well as chymase inhibitors alpha-1-proteinase inhibitor (alpha-1-PI) and alpha-1-antichymotrypsin (alpha-1-AC). RESULTS: The number of tryptase(+) mast cells was significantly higher in the smoker group (84 ± 32 cells/mm(2)) than in the non-smoker group (70 ± 32 cells/mm(2)) (p = 0.044). Likewise, the number of chymase(+) mast cells was higher in the smoker group (89 ± 20 vs. 80 ± 22 cells/mm(2)), though statistical significance was not reached (p = 0.07). No significant difference was observed in alpha-1-PI(+) and alpha-1-AC(+) cells. CONCLUSION: Especially tryptase, but probably also chymase, may have an influence on the skin of smokers, such as wrinkling and aging.

Expression of mast cell tryptase and immunoglobulin E is increased in cutaneous photodamage: implications for carcinogenesis.

Purpose: Mast cells, their serine proteinase tryptase, and immunoglobulin E (IgE) can be involved in cutaneous carcinogenesis.Materials and methods: To study the association of tryptase+ and IgE+ cells with photodamage and skin cancers 385 adult patients (201 males, 184 females, 75 with immunosuppression) at risk of any type of skin cancer were examined. Skin biopsies were taken from the sun-protected medial arm and from the photodamaged dorsal forearm skin followed by immunohistochemical staining for tryptase and IgE.Results: The results show that tryptase+ and IgE+ cells are significantly higher in number in the photodamaged than sun-protected skin, both in immunocompetent and -compromised subjects, and there is a strong correlation between tryptase+ and IgE+ cells. The numbers of forearm tryptase+ and especially IgE+ cells associated significantly with the forearm photodamage severity. In the logistic regression analysis, the forearm to upper arm ratio of IgE+ cells produced a univariate odds ratio of 1.521 (p = .010) and a multivariate one of 3.875 (p = .047) for the history of squamous cell carcinoma. The serum level of total IgE correlated significantly to the IgE to tryptase ratio in both skin sites.Conclusions: Therefore, IgE+ mast cells participate in photodamage and carcinogenesis, though it is unclear whether they are tumor-protective or -causative.

Regular use of vitamin D supplement is associated with fewer melanoma cases compared to non-use: a cross-sectional study in 498 adult subjects at risk of skin cancers.

There are conflicting results on the role of vitamin D system in cutaneous carcinogenesis. Therefore, it was investigated whether the use of oral vitamin D supplements associates with photoaging, actinic keratoses, pigment cell nevi, and skin cancers. In this cross-sectional study, 498 adults (aged 21-79 years, 253 males, 245 females, 96 with immunosuppression) subjects at risk of any type of skin cancer were examined, and possible confounding factors were evaluated. The subjects were divided into three groups based on their self-reported use of oral vitamin D supplements: non-use, occasional use, or regular use. The serum level of 25-hydroxyvitamin-D3 was analyzed in 260 subjects. In 402 immunocompetent subjects, vitamin D use did not associate with photoaging, actinic keratoses, nevi, basal, and squamous cell carcinoma. In contrast, there were lower percentages of subjects with a history of past or present melanoma (32/177, 18.1% versus 32/99, 32.3%, P = 0.021) or any type of skin cancer (110/177, 62.1% versus 74/99, 74.7%, P = 0.027) among regular users compared to non-users. In the logistic regression analysis, the odds ratio for melanoma was 0.447 ( P = 0.016, 95% confidence interval, 0.231-0.862) among regular users. Furthermore, the investigator-estimated risk class of skin cancers was significantly lower among regular users. Serum 25-hydroxyvitamin-D3 did not show marked associations with skin-related parameters. The results on 96 immunosuppressed subjects were somewhat similar, although the number of subjects was low. In conclusion, regular use of vitamin D associates with fewer melanoma cases, when compared to non-use, but the causality between them is obscure.

Patients with a history of atopy have fewer cutaneous melanomas than those without atopy: a cross-sectional study in 496 patients at risk of skin cancers.

The connection between atopy and skin cancers may be related to the stimulation of protective immune response, for example, through autoreactive immunoglobulin-E (IgE), or to the predisposition to carcinogenesis through chronic inflammation. The aim of this study was to investigate whether a past or present atopic disorder is associated with cutaneous photodamage, pigment cell nevi and skin cancers. For this, adult subjects at risk of any type of skin cancer (aged 21-79 years, 250 males, 246 females, 94 with immunosuppression) were examined for past or present malignancies in skin and extracutaneous site (ECS), photodamage, nevi, past or present atopic disorder in skin or mucus membranes, and possible other cancer-related factors. No association between atopy and photodamage, keratinocyte carcinomas or nevus count was found. Instead, there were fewer subjects with melanoma in 171 atopic (14.6%) than in 325 nonatopic subjects (22.2%) ( P = 0.044), and the investigator-estimated risk class of skin cancers was lower in atopic than nonatopic subjects. In all subjects, the multivariate odds ratio (OR) for melanoma was 0.583 ( P = 0.046; 95% confidence interval, 0.343-0.990) in atopic subjects, but in immunocompetent subjects, the reduced risk was confined to mucus membrane atopy (OR, 0.417; P = 0.020). Also, there were fewer subjects with malignancy in ECS in atopic (8.8%) than nonatopic subjects (15.7%) ( P = 0.031). No association between serum total IgE and skin cancers, photodamage, nevi or malignancies in ECS was found. In conclusion, the atopy, especially mucus membrane atopy, is associated with lower percentages of subjects with a history of melanoma.

The BH3-mimetic ABT-737 induces mast cell apoptosis in vitro and in vivo: potential for therapeutics.

Mast cells and their mediators are implicated in the pathogenesis of many different diseases. One possible therapeutic intervention in mast cell-associated diseases can be to reduce the number of tissue mast cells by inducing mast cell apoptosis. In this study, we demonstrate that mast cells exhibit a high sensitivity to ABT-737, a BH3-only mimetic molecule that induces apoptosis through high-affinity binding to the prosurvival proteins, Bcl-2, Bcl-XL, and Bcl-w. Primary mast cells as well as mast cell lines tested succumbed to apoptosis in response to the inhibitor at varying but seemingly low concentrations compared with other leukocytes investigated. I.p. injections of ABT-737 in mice resulted in a total abolishment of mast cells in the peritoneum. Confocal microscopy analysis of peritoneal cells revealed apoptotic bodies of mast cells being phagocytosed by macrophages. In addition, ex vivo treatment of human skin biopsies with ABT-737 demonstrated increased mast cell apoptosis. The data we present in this article show exceptional mast cell sensitivity to ABT-737, a selective inhibitor of antiapoptotic proteins, rendering a possible application for BH3-only mimetic compounds like ABT-737 in mast cell-associated diseases, such as mastocytosis, allergy, asthma, and other chronic inflammations.