Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Simon Vassiliadis is active.

Publication


Featured researches published by Simon Vassiliadis.


Mediators of Inflammation | 1998

Serum levels of pro- and anti-inflammatory cytokines in non-pregnant women, during pregnancy, labour and abortion.

Simon Vassiliadis; Anthi Ranella; Lina Papadimitriou; A. Makrygiannakis; Irene Athanassakis

Disturbance of the cytokine equilibrium has been accused for many pathological disorders. Microbial infections, autoimmune diseases, graft rejection have been correlated to over- or under-production of specific cytokines which are produced as responder molecules to the various immune stimuli. The sole naturally occurring immune reaction in the organism is developed during the gestational period where, despite the presence of a semi-allogeneic graft, maternal immunoreactivity is driven to support fetal growth. The successful embryo development has been attributed to the important intervention of cytokines where some have been characterized as indispensable and others deleterious to fetal growth. However, the physiological levels of many factors during the gestational process have not been determined. Thus, in the present study we have measured and established the values of IL-1alpha, IL-2, IL-3, IL-4, IL-6, IL-10, IL-12, GM-CSF, TNF-alpha and IFN-gamma during all phases of human pregnancy (first, second and third trimester of pregnancy, labour, abortions of the first trimester) as well as in the non-pregnant control state. This is an attempt to assess serum protein concentrations and present the physiological levels of these cytokines at certain time intervals providing thus a diagnostic advantage in pregnancy cases where the mother cannot immunologically support the fetus. Exploitation of this knowledge and further research may be useful for therapeutic interventions in the future.


International Immunopharmacology | 2003

Serum concentrations of growth factors in women with and without endometriosis: the action of anti-endometriosis medicines

Ioannis Matalliotakis; Anastasia G. Goumenou; Georgios Koumantakis; Maria A. Neonaki; Evgenios Koumantakis; Eva Dionyssopoulou; Irene Athanassakis; Simon Vassiliadis

Endometriosis is a common gynecologic syndrome of unknown etiology and pathogenesis. Growth factors and inflammatory mediators produced by peritoneal leukocytes have recently been postulated to participate in the pathogenesis of endometriosis. Angiogenic factors released from peritoneal macrophages may also play a role in the development of this disease. In the present study, we investigate the soluble levels of vascular endothelial growth factor (VEGF), epidermal growth factor-receptor (EGF-R), granulocyte/macrophage-colony stimulating factor (GM-CSF), Insulin-like growth factor-1 (IGF-1) and interferon-gamma (IFN-gamma) in the serum of 28 women with and 20 without endometriosis. We also compared these levels before, during and after treatment with danazol and leuprorelin acetate depot, the two therapeutic regiments of choice concerning this disease. We found that only sVEGF levels were higher in women with endometriosis in comparison to controls (P < 0.001) while sEGF-R is not present. GM-CSF, IGF-1 and IFN-gamma soluble levels are not affected in either healthy or endometriotic subjects. The 6-month treatment with danazol decreased sVEGF levels (P < 0.02) and increased sEGF-R levels (P < 0.001). These observations support the view that VEGF may be associated with the disease process and that danazol may bring sVEGF levels to a normal threshold. However, future studies will be focused on the anti-angiogenic control of the action of VEGF in patients with endometriosis.


International Immunopharmacology | 2001

l-carnitine modifies the humoral immune response in mice after in vitro or in vivo treatment

Irene Athanassakis; M. Mouratidou; P. Sakka; A. Evangeliou; M. Spilioti; Simon Vassiliadis

Although the role of L-carnitine (L-Cn) as a cofactor in the oxidation of long-chain fatty acids has been well established, this agent has also been recognized to have an important role in the regulation of carbohydrate metabolism, and consequently, the maintenance of cell membrane structure and cell viability. L-Cn has been reported to reduce the apoptotic levels of CD4+ and CD8+ cells. It has also been demonstrated to interfere with cells of the monocytic lineage by regulating their ability to produce growth factors that ultimately affect both T and B lymphocytic subsets. Therefore, in this study, we examined whether this agent affects the antigenic response of immune cells and determined the relative numbers of immune cells in the murine spleen after in vitro and in vivo treatment. The results showed that L-Cn reduces the relative numbers of CD8+, CD4+ and Ly5+ cells. This observation was consistent in all systems studied including (a) in vitro inoculation of antigen (DNP-HSA) and L-Cn, (b) in vitro priming of spleen cells treated with L-Cn in vivo, and (c) in vivo immunization and L-Cn administration. In all cases, the reduction of T lymphocytes correlated with the decreased production of interleukin-2. L-Cn, however, did not affect the production of specific antibody, which indicates that the observed reduction of Ly5-positive cells is due to cell differentiation of B cells to plasma cells.


Fertility and Sterility | 2003

Altered expression of interleukin-18 in the peritoneal fluid of women with endometriosis

Aydin Arici; Ioannis Matalliotakis; Anastasia G. Goumenou; Georgios Koumantakis; Simon Vassiliadis; Neal G. Mahutte

OBJECTIVE Peritoneal fluid (PF) inflammatory factors may participate in the pathogenesis of endometriosis. The aim of this study was to investigate PF interleukin (IL)-18 levels in women with and without endometriosis. DESIGN Controlled clinical study. SETTING Women undergoing laparoscopy at a university hospital. PATIENT(S) Fifty women with previously untreated endometriosis, 8 women on GnRH agonists for endometriosis, and 18 control women with normal pelvic anatomy who were undergoing tubal ligation. INTERVENTION(S) Peritoneal fluid IL-18 levels as measured by ELISA. MAIN OUTCOME MEASURE(S) Peritoneal fluid IL-18 levels. RESULT(S) Peritoneal fluid IL-18 levels were significantly higher in women with previously untreated endometriosis (mean +/- SEM, 91.1 +/- 6.5 pg/mL) than in control women (59.4 +/- 2.0 pg/mL). Interestingly, women with superficial (100.0 +/- 10.2 pg/mL) and deep peritoneal implants (94.0 +/- 10.8 pg/mL) had significantly higher PF IL-18 levels than did women with endometriomas (57.8 +/- 1.8 pg/mL). Similarly, women with stage I-II endometriosis (97.3 +/- 8.0 pg/mL), but not women with stage III-IV endometriosis (74.9 +/- 9.9 pg/mL), had significantly higher PF IL-18 levels than did control women. Peritoneal fluid IL-18 levels were significantly higher in the luteal phase than in the follicular phase but did not discriminate between women with pelvic pain or infertility. CONCLUSION(S) Peritoneal fluid IL-18 is elevated in women with peritoneal, minimal- to mild-stage endometriosis.


American Journal of Reproductive Immunology | 1995

Placental Tissue From Human Miscarriages Expresses Class II HLA‐DR Antigens

Irene Athanassakis; Yiannis Aifantis; Antony Makrygiannakis; Eugene Koumantakis; Simon Vassiliadis

PROBLEM: Class II major histocompatibility antigens occupy a central role in the development of humoral or cellular immunologic responses. Surprisingly, in the maternal‐fetal interphase, where two genetically different organisms come in direct contact, these antigens are absent. Based on previous studies in mice we have demonstrated that the absence of class II antigens represents another mechanism of fetal protection from the maternal immune response and, furthermore, that the induction of these antigens in the placenta makes the tissue immunogenic and susceptible to maternal immune attack, leading thus to fetal abortion. In order to test this hypothesis in humans, we analyzed the presence of class II antigens in aborted placentae.


Transplantation Proceedings | 1999

Detection of soluble HLA-G levels in maternal serum can be predictive for a successful pregnancy

Irene Athanassakis; M Paflis; Anthi Ranella; Simon Vassiliadis

THE IDENTIFICATION of HLA-G on placental cytotrophoblast cells opened new insights in defining the initial trigger by which the maternal immune system recognizes the fetal allograft and emits growth signals to the feto-placental unit. The presence of an alternatively spliced mRNA giving rise to secreted HLA-G class I antigens makes these molecules very important candidates for explaining peripheral maternal immunostimulation and immunosuppression during pregnancy. In many cases, especially during transplantation, soluble MHC antigens have been shown to exert immunosuppressive activity. Therefore, during pregnancy, the maternal organism is expected to respond to the semior fully allogeneic fetus in a similar way, where soluble antigens during the first 2 months of gestation elaborate messages that are positive to fetal growth (immunostimulation) and thereafter, equilibrates fetal development by inducing specific immunosuppression. Disability of the maternal organism to elaborate these two types of reaction results in embryo loss, mainly during the first trimester of pregnancy, which in previous studies has been correlated with expression of class II MHC antigens on trophoblasts, normally absent from these cells throughout pregnancy. In the present study, using the monomorphic W6/32 and 7H3 antibodies, we define the levels of soluble HLA-G and HLA-DR respectively in the serum of healthy women before, during, and after pregnancy and compare them to cases of first-trimester fetal abortions of unknown etiology. Taking into consideration the obtained results, along with similar findings from animal experimental abortion models, we conclude that the levels of soluble class I/II in the maternal serum can be predictive to a successful pregnancy outcome.


Journal of Reproductive Immunology | 2001

Soluble ICAM-1 levels in the serum of endometriotic patients appear to be independent of medical treatment

Ioannis Matalliotakis; Simon Vassiliadis; Anastasia G. Goumenou; Irene Athanassakis; Georgios Koumantakis; Maria A. Neonaki; Evgenios Koumantakis

Adhesion molecules regulate the interaction of cells with the extracellular matrix and/or other cells. The intercellular adhesion molecule-1 (ICAM-1; CD54) is a member of the immunoglobulin superfamily and expressed by several cell types, including leukocytes and endothelial cells. A circulating form of the usually membrane-bound molecule was identified and characterized in normal human serum and in sera from patients with endometriosis. In the present study, we established the serum-soluble ICAM-1 (sICAM-1) levels in patients with endometriosis. We also studied the effect of danazol and leuprorelin acetate depot on the levels of sICAM-1. Thirty-eight women, 18-45 years of age, with regular menses and documented pelvic endometriosis were recruited from a University Hospital setting. Twenty-two women with endometriosis were randomly divided into two groups. Danazol (600 mg) were given every day for 6 months, and 3.75 mg of leuprorelin acetate depot every 28 days for 6 months. Serum sICAM-1 concentrations were measured before, during and after treatment, and its quantitative determination was performed by an ELISA technique using a specific immunoassay. We found that (1) sICAM-1 levels were higher in women with endometriosis in comparison to healthy subjects; (2) the 6 month treatment with danazol or leuprorelin acetate depot increased sICAM-1 levels (P<0.001); (3) 3 months after termination of both treatments, sICAM-1 levels were unchanged. Although the mechanism leading to the increase of sICAM-1 needs to be further clarified, any benefits of medical treatment of endometriosis such as danazol or leuprorelin appear to be independent of changes in ICAM-1 serum levels.


Clinical & Developmental Immunology | 2005

Endometriosis and Infertility: A Multi-cytokine Imbalance Versus Ovulation, Fertilization and Early Embryo Development

Simon Vassiliadis; K. Relakis; A. Papageorgiou; Irene Athanassakis

Endometriosis is tightly linked to infertility which is manifested at very early or more advanced stages of the gestational cycle. Alteration on the production of a great number of cytokines/growth factors can be accused for problems on ovum maturation, fertilization or implantation. Yet, macroscopically these stages are characterized by the inability of conception. A closer look of the cytokinic profile during the conceptional and early gestational cycle could, however, localize the problem and allow a therapeutic approach. In this commentary, going through the cytokine requirement during ovulation, fertilization and the early stages of pregnancy, it became possible to specifically define the harmful endometriosis-induced cytokines for each of the conceptional and early gestational stages. Thus, regulating the levels of interferon-γ and tumor necrosis-α will facilitate ovulation and fertilization, whereas adjusting the levels of interleukin-1β and colony stimulating gactor-1 will facilitate implantation.


Immunology Letters | 2002

T-regulatory cells: are we re-discovering T suppressors?

Irene Athanassakis; Simon Vassiliadis

Regulatory T cells are shown to originate form the thymus and their role is to maintain self-tolerance to intra-thymic as well as extra-thymic self-antigens. Their mode of action, using in vivo and in vitro systems, has led to different conclusions as to the need of cell-cell interactions or regulation upon suppressive cytokines. The more we study regulatory T cells the more we find similarities to the old notion of the suppressor T cell network. The limited knowledge in molecular technology in the early 70s and 80s discouraged investigators to further scrutinize the issue and the terms T suppressors and contra-suppressors that were coined back then have been forgotten over the years. It is now time to remember the work of these investigators and attempt to explain their findings using the current knowledge and technology.


Mediators of Inflammation | 2001

The possible anti-inflammatory role of circulating human leukocyte antigen levels in women with endometriosis after treatment with danazol and leuprorelin acetate depot

Ioannis Matalliotakis; Irene Athanassakis; Anastasia G. Goumenou; Maria A. Neonaki; Evgenios Koumantakis; Simon Vassiliadis

BACKGROUND: Endometriosis is defined as an inflammatory condition of the female reproductive tract, a state often associated with infertility and miscarriage. Many exogenously administered factors (treatments) control the disease via as yet unknown pathways. Possible candidate molecules involved in these mechanisms could be the serum-soluble human leukocyte antigens (sHIA) that have been detected in a variety of human body fluids and that are associated with several diseases. AIMS: We here examine how danazol and leuprorelin acetate depot treatments exert their anti-inflammatory action. It is plausible that subtle alterations mediated by these treatments and in relation to sHLA may explain the pathophysiology of endometriosis and provide insights towards new therapeutic protocols. METHODS: Indirect enzyme-linked immunosorbent assay (ELISA), using specific monoclonal antibodies, determined serum-soluble class-I and class-II HLA levels. ELISA readings from treated women were compared with normal healthy subjects. RESULTS: Serum-soluble class-I and class-II HLA levels are statistically significantly lower (P < 0.001) in women with endometriosis than in the control groups. However, danazol but not leuprorelin acetate depot administration augments soluble HLA class I and class II (P < 0.01 and P < 0.001, respectively) to normal levels during the treatment period, an increase that may account for the anti-inflammatory effect and the remission observed. CONCLUSIONS: It is shown that one of the underlying causes of endometriosis may be the lack of both circulating class-I and class-II antigen levels. Danazol administration acts via an induced release of these antigens, whose presence correlates with the degree of the inflammatory alleviation obtained. We thus provide evidence that the inflammatory state of the disease appears to be associated with soluble HLA levels because, 3 months after ceasing therapy, the circulating antigens in the serum return to the same levels that correspond to the pathological condition.

Collaboration


Dive into the Simon Vassiliadis's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge