The Phenotypical Characterization of Dual-Nature Hybrid Cells in Uveal Melanoma

BACKGROUND

Metastasis, occurring years after primary diagnosis, represents a poor prognosis in uveal melanoma (UM)-affected individuals. The nature of cells involved in this process is under debate. Circulating hybrid cells that have combined tumor and immune cell features found in blood were predictive of metastasis and may correspond to dual-nature cells (DNC) in the primary tumor. Herein, we sought to determine the presence of DNCs in primary UM tumors, the cell types involved in their genesis, and their ability to be formed in vitro.

METHODS

UM lesions (n = 38) were immunolabeled with HMB45 in combination with immune-cell-specific antibodies. In parallel, we co-cultured UM cells and peripheral blood mononuclear cells (PBMCs) to analyze DNC formation.

RESULTS

HMB45+/CD45+ DNCs were present in 90% (26/29) of the tumors, HMB45+/CD8+ DNCs were present in 93% (26/28), and HMB45+/CD68+ DNCs were present in 71% (17/24). DNCs formed with CD8+ and CD68+ cells were positively correlated to the infiltration of their respective immune cells. Notably, UM cells were prone to hybridize with PBMCs in vitro.

CONCLUSIONS

This phenotypical characterization of DNCs in UM demonstrates that CD8+ T-cells and macrophages are capable of DNC formation, and they are important for better understanding metastatic dissemination, thus paving the path towards novel therapeutic avenues.

The Macro-Autophagy-Related Protein Beclin-1 Immunohistochemical Expression Correlates With Tumor Cell Type and Clinical Behavior of Uveal Melanoma

Uveal melanoma, in spite of its rarity, represents the most common primitive intraocular malignant neoplasm of the adults; it affects choroid, ciliary bodied and iris and remains clinically silent for a long time, being accidentally discovered by routine ophthalmic exams. Prognosis of uveal melanoma is poor and frequently characterized by liver metastases, within 10-15 years from diagnosis. Autophagy is a multi-step catabolic process by which cells remove damaged organelles and proteins and recycle nutrients. It has been hypothesized that in early stages of tumorigenesis autophagy has a tumor suppressor role while, in more advanced stages, it may represent a survival mechanism of neoplastic cells in response to stress. Several proteins related to autophagy cascade have been investigated in numerous subtypes of human cancer, with overall controversal results. In this paper we studied the immunohistochemical expression of 3 autophagy related proteins (Beclin-1, p62 and ATG7) in a cohort of 85 primary uveal melanoma treated by primary enucleation (39 with metastasis and 46 non metastatic) and correlated their expression with clinico-pathological parameters and blood vascular microvessel density, in order to investigate the potential prognostic role of autophagy in this rare neoplasm. We found that high immunohistochemical levels of Beclin-1 correlated with a lower risk of metastasis and higher disease-free survival times, indicating a positive prognostic role for Beclin-1 in uveal melanoma. No statistically significative differences regarding the expression of ATG7 and p62 between metastatic and non metastatic patients was detected.

The Immune Landscape and Prognostic Immune Key Genes Potentially Involved in Modulating Synaptic Functions in Prostate Cancer

Background: Increasing evidence has indicated an association between differentially expressed genes (DEGs) in tumor-infiltrating immune cells (TIICs) and clinical outcome. The aim of this research is to investigate the influence of tumor microenvironment on the gene expression profile of TIICs and to identify their potential markers for modulating immune cell function in prostate cancer.

Methods: In our research, CIBERSORT algorithm was utilized to calculate the proportion of the TIICs in 164 tumor and 18 control samples from The Cancer Genome Atlas cohort. The differential expression analysis was conducted using R, and then the functional and the pathway enrichments of the DEGs were analyzed using Database for Annotation, Visualization, and Integrated Discovery, followed by integrated regulatory network analysis.

Results: As a result, nTreg, B cells, Th1, and DC cells were significantly increased, accompanied by largely decreased NK and NKT cells. The expressed immune-related gene correlation analysis showed that the signature gene expression extent of CD8 T cells was positively associated with CD4 memory activated T cells but negatively correlated with that of CD4 memory resting T cells. In addition, a total of 128 differentially expressed genes were identified. CytoHubba analysis obtained six hub genes, of which three prognostic-associated potential key molecules including CAV1, FLNA, and VCL were mainly involved in biological processes associated with the regulation of organic substance and synaptic connections.

Conclusions: This study provides a comprehensive understanding of the landscape of TIICs and the roles of the hub genes which may be valuable markers in prostate cancer diagnosis and immunotherapy.

ECHO-7 oncolytic virus Rigvir® in an adjuvant setting for stage I uveal melanoma; A retrospective case report

Purpose

To describe a case of choroidal melanoma treated with Rigvir® virotherapy in an adjuvant setting.

Observations

A female patient born in 1956 presented with a small choroidal melanoma in October 2007. 34 months after transpupillary thermotherapy the state of her eye worsened until tumor growth was visualized. Despite photodynamic therapy and transpupillary thermotherapy the tumor continued to grow locally. In October 2016 enucleation was performed. Since gene expression profile testing disclosed a tumor (class 2) with a high risk of metastasis formation in 5 years, the patient sought options to prevent progression of the disease. In December 2016 virotherapy with Rigvir® was started with 3 administrations for 3 consecutive days. Therapy was continued once per week until March 2017, when the administrations were changed to once per month. The patient is being monitored by an ophthalmologist. She is stable with the virotherapy ongoing and magnetic resonance cholangiopancreatography (7 May 2018) and abdominal ultrasound (23 March 2019) imaging excludes metastasis formation. The quality of life is high.

Conclusions

To the best of our knowledge, this is the first documented case of uveal melanoma treatment with virotherapy as an adjuvant therapy. Considering the few if any available treatments and the encouraging results of the present treatment, virotherapy should be evaluated more extensively as a potential treatment of uveal melanoma.

Localization and Activity of iNOS in Normal Human Lung Tissue and Lung Cancer Tissue

Inducible nitric oxide synthase (iNOS) is one of three enzymes generating nitric oxide (NO) from the amino acid L-arginine. iNOS-derived NO plays an important role in several physiological and pathophysiological conditions. NO is a free radical which produces many reactive intermediates that account for its bioactivity. In the human lung, the alveolar macrophage is an important producer of cytokines and this production may be modified by NO. Moreover, high concentrations of NO have been shown to increase nuclear factor KB (NF-kB) activation. Recent investigations of NO expression in tumor tissue indicated that, at least for certain tumors, NO may mediate one or more roles during the growth of human cancer. We have studied iNOS in two tissue groups: normal human lung tissue and human lung cancer tissue. We localized iNOS in these tissues by immunohistochemistry and tested the mRNA expression by RT-PCR, the protein level by Western blot, and the protein activity by radiometric analysis. The results demonstrate different expression, localization and activity of iNOS in normal versus tumor tissue. This is suggestive of a role for NO production from iNOS in human lung cancer because high concentrations of this short molecule may transform to highly reactive compounds such as peroxynitrite (ONOO-); moreover, through the upregulator NF-kB, they can induce a chronic inflammatory state representing an elevated risk for cell transformation to cancer.

Molecular profiling of primary uveal melanomas with tumor-infiltrating lymphocytes

In contrast to other cancers, the presence of tumor-infiltrating lymphocytes (TILs) in uveal melanoma is associated with a poor prognosis. However, how TILs may promote disease progression and what regulates their infiltration has not yet been established. To address these clinically relevant outstanding questions, T cell, immune regulatory, and chemokine gene expression profiles of 57 enucleated uveal melanoma tumors were compared, encompassing 27 with TILs and 30 without,. Tumors with infiltrating lymphocytes expressed more CD8A mRNA, as well as IFNG, TGFB1, and FOXP3 transcripts. Other T helper associated cytokines and T helper transcription factors were not differentially expressed, nor were mediators of lymphocyte cytotoxicity. The immune inhibitors INDO, PDCA1, CTLA4, and LAG3, and the non-classical MHC Class I target of CD8⁺ T regulatory cells, HLA‑E, were significantly higher in tumors with TILs. FAS was also significantly higher. The C-C chemokine ligands CCL4, CCL5, and CCL20 were higher in tumors with TILs. Levels of CCL5 were most strongly correlated with levels of CD8A. Chemokine receptors were not differentially expressed. Molecular profiling of uveal melanoma tumors with TILs supports the existence of an immunosuppressive tumor microenvironment and suggests roles for CD8⁺ regulatory T cells, as well as specific chemokines, in fostering uveal melanoma disease progression.

Immune reconstitution from peripheral blood mononuclear cells inhibits lung carcinoma growth in NOD/SCID mice

Drug resistance and immune deficiency are important factors for the poor prognosis of lung carcinoma. The present study explored the possible protective effect of immune reconstitution from peripheral blood mononuclear cells (PBMCs) on multi-drug-resistant human lung carcinoma Am1010 cells in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. The inoculated tumor fragments grew rapidly in the NOD/SCID mice. The growth was significantly inhibited by intraperitoneal injection of PBMCs. In the mice injected with PBMCs, numerous CD3⁺ and CD8⁺ cells, but less CD4⁺ cells, were found in spleen and tumor tissues. These data suggest that PBMC transplantation inhibits lung carcinoma progression via the reconstitution of the immune system, particularly of cytotoxic T lymphocytes.

Circulating immune cell and microRNA in patients with uveal melanoma developing metastatic disease

BACKGROUND

The immune response has been implicated in the control of uveal melanoma progression. Epigenetic mechanisms mediated by specific microRNAs (miRs) regulate immune responses.

METHODS

Blood was drawn from six patients with uveal melanoma followed from diagnosis, at which time there was no clinical or radiographic evidence of metastasis, until metastasis manifested. Circulating T cell, natural killer (NK), natural killer T (NKT), and myeloid suppressor cell populations were assessed by flow cytometry. CD3(+), CD15(+), and CD56(+) cells were isolated using immunomagnetic beads. Plasma and cellular levels of immune regulatory miRs were determined by quantitative polymerase chain reaction assays.

RESULTS

The development of metastasis was associated with decreases in circulating CD3(-)CD56(dim) NK cells and CD8(+) and double-negative CD3(+)CD56(+) NKT cells. ICOS(+)CD4(+)FoxP3(+) T regulatory cells and CD11b(+)CD14(-)CD15(+) myeloid suppressor cells increased. Plasma levels of miR-20a, 125b, 146a, 155, 181a, and 223 were higher in the study patients at diagnosis compared to controls. Plasma levels of miR-20a, 125b, 146a, 155, and 223 increased, and miR-181a decreased when metastasis manifested. Alterations in immune regulatory miRs were also observed in CD3(+), CD15(+), and CD56(+) cell populations.

CONCLUSIONS

The development of metastasis in uveal melanoma is associated with changes in immune effector and regulatory cells consistent with lessening tumor immune surveillance. These changes are associated with changes in plasma and cellular levels of immune regulatory miRs. The results may help guide uveal melanoma immunotherapy and biomarker development.

Prognostic impact of peritumoral lymphocyte infiltration in soft tissue sarcomas

BACKGROUND

The purpose of this study was to clarify the prognostic significance of peritumoral lymphocyte infiltration in the capsule of soft tissue sarcomas (STS). Multiple observations in preclinical and clinical studies have shown that the immune system has a role in controlling tumor growth and progression. Prognostic markers in potentially curable STS should guide therapy after surgical resection. The immune status at the time of resection may be important, but the prognostic significance of peritumoral lymphocytes is unknown.

METHODS

Tissue microarrays from 80 patients with STS were constructed from duplicate cores of tissue from the tumor and the peritumoral capsule. Immunohistochemistry was used to evaluate the CD3+, CD4+, CD8+ and CD20+ lymphocytes in the tumor and the peritumoral capsule.

RESULTS

In univariate analyses, increasing numbers of CD20+ (P = 0.032) peritumoral lymphocytes were associated with a reduced disease free survival (DSS). In multivariate analyses, a high number of CD20+ peritumoral lymphocytes (P = 0.030) in the capsule was an independent negative prognostic factor for DSS. There were no such associations of lymphocyte infiltration in the tumor.

CONCLUSIONS

A high density of CD20+ peritumoral lymphocytes is an independent negative prognostic indicator for patients with STS. Further research is needed to determine whether CD20 cells in the peritumoral capsule of STS may promote tumor invasion in the surrounding tissue and increase the metastatic potential.

Increased levels of tumor-infiltrating lymphocytes are associated with improved recurrence-free survival in stage 1A non-small-cell lung cancer

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) have been found to increase survival in many forms of cancer, including, endometrial, bile ductal, colonic, esophageal, and urothelial cancers, as well as melanoma and follicular lymphoma. The relevance of TILs in the prognosis of non-small-cell lung cancer (NSCLC), however, still remains controversial. We compared the outcomes of stage 1A NSCLC with and without tumor infiltrating lymphocytes to evaluate the effects of TILs on recurrence and survival patterns.

MATERIALS AND METHODS

From 2000 to 2009, 273 anatomic segmentectomies and lobectomies were performed on stage 1A NSCLC. Patients were stratified into TIL- and TIL+ cohorts based on pathologic evaluation. Further investigation was conducted on the effects of TILs in patients with and without angiolymphatic invasion. Variables analyzed include overall survival, recurrence-free survival, and type of recurrence.

RESULTS

Overall 5-y survival was not affected by TIL status (65% versus 60%, P = 0.469). Five-year recurrence-free survival (RFS) was significantly increased in the TIL+ group versus the TIL- group (87% versus 73%, P = 0.011), most significantly in women (P = 0.016). The presence of angiolymphatic invasion (ALI) was associated with decreased 5-y RFS versus patients without ALI (61% versus 85%, P < 0.001). Interestingly, in the ALI negative group, TIL+ patients experienced a significantly increased 5-y recurrence-free survival versus TIL- patients (93% versus 80%, P = 0.036).

CONCLUSIONS

High levels of intratumoral TILs are associated with improved recurrence-free survival in stage 1A NSCLC patients as well as a reduced likelihood of systemic recurrence. When angiolymphatic invasion is not present, the beneficial effects of TILs become even more profound.

CTL induction of tumoricidal nitric oxide production by intratumoral macrophages is critical for tumor elimination

To characterize mechanisms of CTL inhibition within an ocular tumor microenvironment, tumor-specific CTLs were transferred into mice with tumors developing within the anterior chamber of the eye or skin. Ocular tumors were resistant to CTL transfer therapy whereas skin tumors were sensitive. CTLs infiltrated ocular tumors at higher CTL/tumor ratios than in skin tumors and demonstrated comparable ex vivo effector function to CTLs within skin tumors indicating that ocular tumor progression was not due to decreased CTL accumulation or inhibited CTL function within the eye. CD11b(+)Gr-1(+)F4/80(-) cells predominated within ocular tumors, whereas skin tumors were primarily infiltrated by CD11b(+)Gr-1(-)F4/80(+) macrophages (Ms), suggesting that myeloid derived suppressor cells may contribute to ocular tumor growth. However, CD11b(+) myeloid cells isolated from either tumor site suppressed CTL activity in vitro via NO production. Paradoxically, the regression of skin tumors by CTL transfer therapy required NO production by intratumoral Ms indicating that NO-producing intratumoral myeloid cells did not suppress the effector phase of CTL. Upon CTL transfer, tumoricidal concentrations of NO were only produced by skin tumor-associated Ms though ocular tumor-associated Ms demonstrated comparable expression of inducible NO synthase protein suggesting that NO synthase enzymatic activity was compromised within the eye. Correspondingly, in vitro-activated Ms limited tumor growth when co-injected with tumor cells in the skin but not in the eye. In conclusion, the decreased capacity of Ms to produce NO within the ocular microenvironment limits CTL tumoricidal activity allowing ocular tumors to progress.

Tumor cells disseminate early, but immunosurveillance limits metastatic outgrowth, in a mouse model of melanoma

Although metastasis is the leading cause of cancer-related death, it is not clear why some patients with localized cancer develop metastatic disease after complete resection of their primary tumor. Such relapses have been attributed to tumor cells that disseminate early and remain dormant for prolonged periods of time; however, little is known about the control of these disseminated tumor cells. Here, we have used a spontaneous mouse model of melanoma to investigate tumor cell dissemination and immune control of metastatic outgrowth. Tumor cells were found to disseminate throughout the body early in development of the primary tumor, even before it became clinically detectable. The disseminated tumor cells remained dormant for varying periods of time depending on the tissue, resulting in staggered metastatic outgrowth. Dormancy in the lung was associated with reduced proliferation of the disseminated tumor cells relative to the primary tumor. This was mediated, at least in part, by cytostatic CD8+ T cells, since depletion of these cells resulted in faster outgrowth of visceral metastases. Our findings predict that immune responses favoring dormancy of disseminated tumor cells, which we propose to be the seed of subsequent macroscopic metastases, are essential for prolonging the survival of early stage cancer patients and suggest that therapeutic strategies designed to reinforce such immune responses may produce marked benefits in these patients.

Immune escape mechanisms of intraocular tumors

The notion that the immune system might control the growth of tumors was suggested over 100 years ago by the eminent microbiologist Paul Ehrlich. This concept was refined and expanded by Burnet and Thomas 50 years later with their articulation of the "immune surveillance" hypothesis. In its simplest form, the immune surveillance hypothesis suggests that neoplasms arise spontaneously and express novel antigens that are recognized by the immune system, which either eliminates the tumors or restrains their growth. Within the eye, immune responses are controlled and sometimes profoundly inhibited - a condition known as immune privilege. Immune privilege in the eye is the result of a complex array of anatomical, physiological, and immunoregulatory mechanisms that prevent the induction and expression of many immune responses. Tumors arising in the eye would seem to have an advantage in evading immune surveillance due to ocular immune privilege. Uveal melanoma, the most common and malignant intraocular tumor in adults, not only benefits from the immune privilege of the eye but also has adopted many of the mechanisms that contribute to ocular immune privilege as a strategy for protecting uveal melanoma cells once they leave the sanctuary of the eye and are disseminated systemically in the form of metastases. Although the immune system possesses a battery of effector mechanisms designed to rid the body of neoplasms, tumors are capable of rapidly evolving and countering even the most sophisticated immunological effector mechanisms. To date, tumors seem to be winning this arms race, but an increased understanding of these mechanisms should provide insights for designing immunotherapy that was envisioned over half a century ago, but has failed to materialize to date.

Prognostic effect of epithelial and stromal lymphocyte infiltration in non-small cell lung cancer

PURPOSE

The major value of prognostic markers in potentially curable non-small cell lung cancer (NSCLC) should be to guide therapy after surgical resection. In this regard, the patients' immune status at the time of resection may be important and also measurable. The immune system has paradoxical roles during cancer development. However, the prognostic significance of tumor-infiltrating lymphocytes is controversial. The aim of this study is to elucidate the prognostic significance of epithelial and stromal lymphocyte infiltration in NSCLC.

EXPERIMENTAL DESIGN

Tissue microarrays from 335 resected NSCLC, stage I to IIIA were constructed from duplicate cores of viable and representative neoplastic epithelial and stromal areas. Immunohistochemistry was used to evaluate the epithelial and stromal CD4+, CD8+, and CD20+ lymphocytes.

RESULTS

In univariate analyses, increasing numbers of epithelial CD8+ (P = 0.023), stromal CD8+ (P = 0.002), epithelial CD20+ (P = 0.023), stromal CD20+ (P < 0.001), and stromal CD4+ (P < 0.001) lymphocytes correlated significantly with an improved disease-specific survival. No such relation was noted for epithelial CD4+ cells. Furthermore, a low level of stromal CD8+ lymphocyte infiltration was associated with an increased incidence of angiolymphatic invasion (P = 0.032). In multivariate analyses, a high number of stromal CD8+ (P = 0.043) and CD4+ (P = 0.002) cells were independent positive prognostic factors for disease-specific survival.

CONCLUSIONS

High densities of CD4+ and CD8+ lymphocytes in the stroma are independent positive prognostic indicators for resected NSCLC patients. This may suggest that these cells are mediating a strong antitumor immune response in NSCLC.

Expression of Co-stimulatory molecules on langerhans cells in lesional epidermis of human atopic dermatitis

Langerhans cells (LC) are immature dendritic cells (DC) present in the skin epithelium. To understand the molecular and cellular mechanisms governing the inflammatory reaction in atopic dermatitis (AD), the expression of the LC specific marker CD1a, a member of major histocompatibility (MHC)-like glycoproteins, and the co-stimulatory molecules CD80 and CD86, expressed on functionally mature dendritic cells, were counted in lesional biopsies and normal epidermis by an immunohistochemical method. CD1a specific staining was observed in both normal and AD lesion specimens. CD80 and CD86 positive cells with morphological characteristics of the LC were found in lesional AD epidermis, suggesting a high level of functional maturity of these cells and their involvement in chronic inflammatory disease.

Uveal melanoma expression of indoleamine 2,3-deoxygenase: establishment of an immune privileged environment by tryptophan depletion

The enzyme indoleamine 2,3-dioxygenase (IDO) catalyzes degradation of tryptophan, an essential amino acid required for lymphocyte activation and proliferation. Many tumors express IDO which implies that it acts as a mechanism to evade T cell-mediated immune attack, and also to establish an immunosuppressive tumor microenvironment. The purpose of this study was to determine whether primary and metastatic uveal melanoma expressed the IDO gene and whether uveal melanoma cells could deplete tryptophan. In situ expression of IDO in primary uveal melanoma from tumor bearing eyes and metastatic uveal melanoma liver tissues was determined by immunohistostaining with IDO-specific antibody. Reverse transcription PCR was used to assess IDO gene transcription by primary and metastatic uveal melanoma cell lines. IDO protein expression was determined by Western blot of uveal melanoma cell protein lysate. IDO catalytic activity was assessed by measuring the presence of kynurenine, a product generated by tryptophan degradation, in uveal melanoma culture supernatants. Primary uveal melanoma from tumor-bearing eyes and metastatic uveal melanoma from the liver did not express IDO in situ. IDO was not constitutively expressed in either primary or metastatic uveal melanoma cell lines. However, stimulation of primary and metastatic uveal melanoma cell cultures with interferon-gamma (IFN-gamma) universally upregulated both IDO gene and protein expression. Culture supernatants from IFN-gamma treated primary and metastatic uveal melanoma cell cultures contained elevated levels of kynurenine. Addition of the IDO inhibitor 1-methyl dl-tryptophan significantly diminished kynurenine levels in IFN-gamma treated uveal melanoma cell cultures. The results from this study suggest that IFN-gamma inducible IDO upregulation by primary and metastatic uveal melanoma may generate a local immune privileged microenvironment to promote escape from T cell-mediated immune surveillance.

In vitro stem cell cultures from human dental pulp and periodontal ligament: new prospects in dentistry

In spite of the vast knowledge of tooth development and of the various kinds of specialized bone/tooth-associated cells, the characteristics and properties of their precursor cell populations present in the postnatal organism are little known, as is their possible therapeutic use. Taken together dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) possess stem-cell-like qualities, including self-renewal capability and multi-lineage differentiation. Regenerative medicine is based on stem cells, signals and scaffolds. Transplantation of those cells, which can be obtained from an easily accessible tissue resource and expanded in vitro, holds promise as a therapeutic approach for reconstruction of tissues and bone in vivo.

Cancer immunoediting from immune surveillance to immune escape

Cancer immune surveillance is considered to be an important host protection process to inhibit carcinogenesis and to maintain cellular homeostasis. In the interaction of host and tumour cells, three essential phases have been proposed: elimination, equilibrium and escape, which are designated the 'three E's'. Several immune effector cells and secreted cytokines play a critical role in pursuing each process. Nascent transformed cells can initially be eliminated by an innate immune response such as by natural killer cells. During tumour progression, even though an adaptive immune response can be provoked by antigen-specific T cells, immune selection produces tumour cell variants that lose major histocompatibility complex class I and II antigens and decreases amounts of tumour antigens in the equilibrium phase. Furthermore, tumour-derived soluble factors facilitate the escape from immune attack, allowing progression and metastasis. In this review, the central roles of effector cells and cytokines in tumour immunity, and the escape mechanisms of tumour cells during tumour progression are discussed.

Expression and secretion of CXCL8 (IL-8), release of tryptase and transcription of histidine decarboxylase mRNA by anti-IgE-activated human umbilical cord blood-derived cultured mast cells

Activation of cytokine receptors and alterations in cytokines are thought to play important roles in neuronal dysfunction and in the pathogenesis of the nervous system diseases. CXCL8 (IL-8) is a CXC chemokine with chemotactic and inflammatory properties. Chemokines control mast cell infiltration in several inflammatory diseases, including stress and neurological dysfunctions. Using isolated human umbilical cord blood-derived cultured mast cells (HUCMC) from hematopoietic stem cells CD34+, mast cells were immunologically activated with anti-IgE at concentrations of 1, 5, 10 and 20 microg/ml leading to the dose-dependent production of IL-8 (p < 0.05). The increase in IL-8 mRNA expression was also noted when the cells were treated with anti-IgE at 10 microg/ml for 6 h. Immunologically activated HUCMC provoked the generation of tryptase in a dose- and time-dependent manner. We also found increased histidine decarboxylase (HDC) expression in activated HUCMC after 6 h of incubation, a rate-limiting enzyme responsible for the generation of histamine from histidine. Taken together, these results confirm that anti-IgE-activated mast cells release inflammatory mediators including CXCL8, a CXC chemokine which regulates several biological effects of mast cells, e.g. chemoattraction, and possibly causes cell arrest.

Inhibitory effect of quercetin on tryptase and MCP-1 chemokine release, and histidine decarboxylase mRNA transcription by human mast cell-1 cell line

Mast cells are important in reactions of allergic disease and are also involved in a variety of neuroinflammatory diseases. Mast cells can be immunologically activated by IgE through their Fc receptors, as well as by neuropeptides and cytokines to secrete mediators. Here we used a human mast cell-1 (HMC-1) cell line cultured and treated with a physiological activator, anti-IgE, and a nonphysiological activator, calcium ionophore A23187, for tryptase and MCP-1 generation and transcription of histidine decarboxylase. We used quercetin, a potent antioxidant, cytoprotective and anti-inflammatory compound capable of inhibiting histamine and some cytokines released from several cell types, as an inhibitor of immunological and nonimmunological stimulus for mast cells. In this study quercetin inhibits, in a dose-response manner, tryptase and MCP-1. Moreover, using RT-PCR quercetin inhibited the transcription of histidine decarboxylase, the rate-limiting enzyme responsible for the generation of histamine from histidine, and MCP-1. Our data suggest that quercetin is an important and good candidate for reducing the release of pro-inflammatory mast cell mediators activated by physiological and nonphysiological stimulators.