PubMed Health⌕ Search

Biomedical subjects

Matthias Schott

Publications and source records attributed to Matthias Schott.

13 recordsLinked to original sources
PubMed2006

Corticotropin-releasing hormone receptor expression on normal and tumorous human adrenocortical cells.

Corticotropin-releasing hormone (CRH) is not only the principal regulator of the central hypothalamic-pituitary-adrenal (HPA) axis but also exerts direct actions on peripheral tissues. We analyzed the expression of CRH receptors in microdissected preparations of normal human adrenal glands and in adrenocortical and adrenomedullary tumors, employing immunohistochemistry, quantitative RT-PCR of microdissected adrenal tissues, and in situ hybridization. The effect of CRH on adrenal steroidogenesis was tested in adrenal cells. Immunoreactive CRH1R was found primarily within the zona reticularis. In addition, we found a higher expression of CRH type-1 and 2 receptors mRNAs in preparations of adrenal cortices as compared to pheochromocytomas, a 6-fold increase in preparations of clinically unapparent adrenocortical adenomas, and a 10- to 60-fold increase in cortisol-producing adrenal adenomas. Stimulation of the adrenal tumor cell line NCI-H295R with CRH elicited a 1.4-fold increase in DHEA secretion. This result could be reproduced in a culture of primary human adrenocortical cells. We conclude that adrenocortical cells exhibit a higher expression of functional CRH receptors than chromaffin cells and that CRH acts on adrenal DHEA production. The data support the assertion of a direct action of CRH on human adrenocortical cells in addition to an intra-adrenal CRH receptor/adrenocorticotropin system. Enhanced CRH1R expression may be involved in adrenocortical tumorigenesis.

Adrenal Cortex↗
PubMed2006

Dendritic cells as potential adjuvant for immunotherapy in adrenocortical carcinoma.

OBJECTIVE: Adrenocortical carcinoma (ACC) is a rare malignancy associated with a dismal prognosis. Dendritic cells (DCs) are professional antigen-presenting cells leading to an antitumour immune response. The aim of this study was to elaborate two methods of antigen delivery to DCs and to evaluate an immunotherapy protocol in ACC patients. DESIGN/PATIENTS: Autologous DCs were pulsed with autologous tumour lysate (TL). Fusion of DCs with tumour cells was based on a polyethylene glycol method. Two patients with metastasized hypersecretory ACC were vaccinated twice. MEASUREMENTS: In vitro data were quantified by measurement of PBMC (peripheral blood mononuclear cell) responses and cytokine secretion and by flow cytometry analyses. Clinical response was monitored by CT scan of tumour mass and measurement of angiogenic factors. RESULTS: The maximum loading of TL was obtained at 24 h as 48.2% (+/- 26.8%) of DCs were TL-positive. The DC/tumour cell fusion efficacy was approximately 45% as shown by double positive staining for ACTH receptor and DC-specific CD83. In vivo DC vaccination resulted in positive delayed-type hypersensitivity skin reactions reflecting specific memory T-lymphocyte reaction. In vitro analyses revealed specific T-cell proliferation in patient 1 (stimulation index: 5.7 compared to pretreatment) and induction of cytotoxic granzyme B secreting T cells in patient 2 (0.41% CD8 + cells vs. 0.06% pretreatment) as indicators of specific cytotoxic T cells. Although angiogenic serum markers could be stabilized, no impact on tumour growth could be observed. CONCLUSION: Our data demonstrate that autologous dendritic cells induce antigen-specific Th1 immunity in adrenocortical carcinoma. The clinical outcome, however, was not improved in the patients studied here.

Adjuvants, Immunologic↗
PubMed2006

A case of catecholamine and glucocorticoid excess syndrome due to a corticotropin-secreting paraganglioma.

We present a case of a 61-year-old female patient with ectopic corticotropin (ACTH) syndrome, hypopituitarism, and catecholamine excess due to a paraganglioma at the inferior pole of the left kidney. In this article we discuss the hormonal findings in the patient and its consequences, the pitfalls of the endocrine workup, and the results of our immunohistological and molecular studies in more detail.

Adrenocorticotropic Hormone↗
PubMed2006

Expression of connexins in chromaffin cells of normal human adrenals and in benign and malignant pheochromocytomas.

Decrease in connexin (Cx) expression and loss of gap junctional intercellular communication (GJIC) have been associated with aberrant cell growth and enhanced neoplastic phenotype. We studied the expression of Cx26, Cx32, Cx43, and Cx50 in chromaffin cells of 10 normal human adrenal glands, 10 benign, and 13 malignant pheochromocytomas. Immunohistochemistry showed that Cx50 expression seemed to be the predominant form of Cx expressed in human chromaffin cells, whereas Cx43 immunoreactivity was the most prominent form found in the adrenal cortex. However, Western blotting revealed that nonphosphorylated and singly and doubly phosphorylated forms of Cx43 were present within the malignant adrenomedullary cells at the same time. Cx26 and Cx32 were distributed inhomogeneously with no emphasis of expression in the types of tissues studied. Cx50 expression was diminished in malignant pheochromocytomas. We conclude that there is a differential expression of Cx in human adrenals. Immunohistological testing for Cx expression does not however allow differentiation of benign from malignant pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMed2006

Immunesurveillance by dendritic cells: potential implication for immunotherapy of endocrine cancers.

Dendritic cells (DCs) are highly efficient antigen-presenting cells in the immune system with the potential to regulate the system and induce a cytotoxic T-cell response. As a proof of principle, a multitude of animal and human studies has demonstrated that immunization with antigen-loaded DCs may lead to anti-tumour immune responses with tumour regression and rejection of cancer. The identification of tumour antigens that can be recognized by T lymphocytes has facilitated the development of new protocols and enabled immunologists to monitor immune responses. However, to date, long-term clinical effects on larger numbers of cancer patients are missing, and there is no generally accepted DC generation or activation protocol. This review will focus on the most important findings on the role of DCs within the immune system and how to generate and activate these cells in order to induce cytotoxic immunity in non-endocrine and endocrine malignancies. Recently, we and other researchers reported on DC vaccinations in patients with endocrine malignancies mainly in metastasized medullary thyroid carcinoma resulting in tumour-specific immunity and partial clinical responses in some cases. Based on these and other in vitro data, new DC vaccination protocols for the treatment of patients with endocrine tumours have now been conducted.

Antigens, Neoplasm↗
PubMed2005

Thyrotropin receptor autoantibodies in Graves' disease.

Clinical thyrotoxicosis in Graves' disease patients is caused by thyrotropin receptor (TSHR)-stimulating autoantibodies. The molecular mechanisms of TSHR post-translational modification, TSHR signaling and TSHR-autoantibody interaction are still debatable, and the precise interaction of stimulating and blocking autoantibodies with TSHR is unclear. Recent TSHR epitope studies indicate that binding sites for stimulating and blocking autoantibodies are close together, not on distinct or distant parts of the molecule. Furthermore, new methods to detect TSHR autoantibodies and their clinical use are addressed. Highly sensitive TSHR autoantibody assays are widely available and cost efficient, and their routine clinical use might help in the differential diagnosis of hyperthyroidism and disease outcome prediction in patients with high levels of TSHR autoantibodies.

Autoantibodies↗
PubMed2004

Expression of the tyrosine kinase c-kit is an independent prognostic factor in patients with small cell lung cancer.

In a retrospective analysis of 203 patients with small cell lung cancer (SCLC), we examined the prognostic value of c-kit expression on survival. Expression of c-kit was examined immunohistochemically in formalin-fixed, paraffin-embedded tissue sections. c-kit was observed in 87.7% of SCLC tumors. Using the Kaplan-Meier model, we found that lack of c-kit expression was associated with significantly shorter survival time compared to the presence of c-kit expression (mean survival 151 +/- 27 vs. 358 +/- 49 days, p = 0.0084). Moreover, the proportion of c-kit(+) cells within the tumor was also related to survival time. Patients with tumors in which >75% of cells stained positive for c-kit had a mean overall survival time of 424 (+/-72) compared to 295 (+/-67) days for patients with 25-75% c-kit(+) tumor cells. Patients with tumors containing <25% c-kit(+) cells had the worst survival, with 164 (+/-24) days (p = 0.0033). Further parameters associated with short survival times were low performance status, elevated levels of lactate dehydrogenase and higher stage according to the TNM classification. Multivariate analysis using the Cox regression model showed that the proportion of c-kit(+) cells within the tumor specimen was one of 3 independent prognostic parameters (p = 0.004) for overall survival next to TNM classification (p = 0.001) and performance status (p < 0.001).

Aged↗
PubMed2004

Dendritic cell-based immunotherapy in thyroid malignancies.

A new approach for anti-tumor immunotherapy is to use dendritic cells (DCs) as adjuvants in order to actively immunize cancer patients with antigens specifically expressed in tumor cells. DCs possess a unique capacity to effectively activate CD4+ T helper cells and CD8+ cytotoxic T cells. During the last years, several clinical trials in various malignancies demonstrated that immunizations with tumor antigen pulsed DCs could break the tolerance of the immune system against antigens expressed by the tumor cells resulting in partial or complete remission in some cases. This review describes the most important findings on the interaction between DCs and T cells as well as natural killer cells and summarizes recent data on DC vaccination of endocrine and non-endocrine malignancies. The results from current pilot studies suggest that DC vaccination may represent a promising strategy for the development of an anti-cancer vaccine to treat chemotherapy and radioresistant endocrine malignancies.

Animals↗
PubMed2002

Calcitonin-specific antitumor immunity in medullary thyroid carcinoma following dendritic cell vaccination.

In this study, we investigated the immune response following immunotherapy with calcitonin-pulsed dendritic cells (DC) in 7 patients with metastasized medullary thyroid carcinoma. After immunization with 1-5 x 10(6) autologous DC, significant calcitonin-specific T cell proliferation was detectable in 3 patients. Measurement of cytokine release from T lymphocytes demonstrated high post-treatment interferon-gamma (IFN-gamma) secretion after stimulation with calcitonin in 5 patients, one of whom experienced significant tumor regression. In contrast, antigen-specific interleukin-4 (IL-4) production was only slightly increased in 4 patients. All 7 patients developed a strong delayed-type hypersensitivity (DTH) skin reaction, which was confirmed to be mediated by infiltrating CD4+ T-helper cells and CD8+ cytotoxic T cells in all 3 patients who underwent skin biopsy. This is the first study to show that a polypeptide hormone can be used to develop a DC vaccination strategy for the immunotherapy of highly malignant endocrine cancers.

Adult↗
PubMedDate not supplied

Dendritic cell vaccination: new hope for the treatment of metastasized endocrine malignancies.

Dendritic cells (DCs) are antigen-presenting cells that are involved in the induction of primary immune responses. The unique ability of DCs to activate naive and memory CD4+ and CD8+ T cells suggests that they could be used for the induction of a specific antitumour immunity. In the past few years, several in vitro and in vivo studies in rodents and humans have demonstrated that immunizations with DCs pulsed with tumour antigens result in protective immunity and rejection of established tumours in various malignancies. Here, we focus on recent results of how DCs regulate immune responses that are important for generating antitumour cytotoxic T cells, and summarize clinical vaccination trials for the treatment of endocrine and nonendocrine carcinomas. Preliminary results suggest that DC vaccines might be novel tools for antitumour immunotherapies to treat chemotherapy-resistant and radioresistant endocrine cancers, such as metastasized medullary thyroid carcinomas and other neuroendocrine carcinomas.

Animals↗