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Behaviour of Cytokine Levels in Serum and Peritoneal Fluid of Women with Endometriosis

Endometriosis is a disorder characterised by presence and growth of endometrial tissue outside the uterus, primarily into the peritoneum. The peritoneal fluid (PF) of women with endometriosis undergoes a number of biological changes, including local inflammatory-reparative phenomena and peripheral blood mononuclear cells (PBMC) involvement. These activated cells as well as the endometriotic cells secrete various cytokines with pleiotropic biological activities. Dynamic interplay among cytokines may contribute to realise a favourable microenvironment for the implantation of endometrial cells and the progression of the disease. In the present study, we evaluated the levels of cytokines, such as the tumour necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β), interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) in PF and in serum (S) of women with endometriosis to compare their behaviour in both biological fluids. The patients (n = 26) were women of reproductive age attending our observation centre for infertility, diagnosed endometriosis at laparoscopy. Control group (n = 5) consisted of women affected by non-immunologic infertility, diagnosed by explorative laparoscopy. S samples were obtained from peripheral blood before anaesthesia and laparoscopy. PF samples were collected at the time of laparoscopy. Both biological fluids were examined for cytokine by ELISA assays. Our results showed that S and PF levels of TNF-α, not dosable in controls, were very high at the early stage and decreased significantly with the severity of the disease (p < 0.001). TGF-β levels were significantly (p < 0.001) higher than in controls and increased with the severity of the disease (p < 0.001), particularly in the PF. S and PF IL-8 as well as MCP-1 concentrations at all stages were higher than in controls (p < 0.001), yet showed an opposite behaviour in both biological fluids. In fact, S levels of IL-8 and MCP-1 were significantly (p < 0.001) higher at early stages and decreased with the severity of the disease, whereas we observed a significant (p < 0.001) enhancement of these chemokine levels in PF from stage I to stage II and stage III. These observations showed that TNF-α and TGF-β levels were overlapping in S and PF of women with endometriosis. On the contrary, MCP-1 and IL-8 S concentrations decreased with the severity of the disease, whereas PF levels showed markedly increased at severe stages. Taken together the observed changes may be due both to the increased peritoneal macrophage activity and to the larger recruitment of PBMC and autocrine release by endometriotic cells.

Interplay between Misplaced Müllerian-Derived Stem Cells and Peritoneal Immune Dysregulation in the Pathogenesis of Endometriosis

In the genetic regulation of Müllerian structures development, a key role is played by Hoxa and Wnt clusters, because they lead the transcription of different genes according to the different phases of the organogenesis, addressing correctly cell-to-cell interactions, allowing, finally, the physiologic morphogenesis. Accumulating evidence is suggesting that dysregulation of Wnt and/or Hox genes may affect cell migration during organogenesis and differentiation of Müllerian structures of the female reproductive tract, with possible dislocation and dissemination of primordial endometrial stem cells in ectopic regions, which have high plasticity to differentiation. We hypothesize that during postpubertal age, under the influence of different stimuli, these misplaced and quiescent ectopic endometrial cells could acquire new phenotype, biological functions, and immunogenicity. So, these kinds of cells may differentiate, specializing in epithelium, glands, and stroma to form a functional ectopic endometrial tissue. This may provoke a breakdown in the peritoneal cavity homeostasis, with the consequent processes of immune alteration, documented by peripheral mononuclear cells recruitment and secretion of inflammatory cytokines in early phases and of angiogenic and fibrogenic cytokines in the late stages of the disease.

Dysregulation of the Fas/FasL system in mononuclear cells recovered from peritoneal fluid of women with endometriosis

In endometriosis, regurgitating endometrial cells fail to undergo apoptosis and implant themselves outside the uterus, particularly in the peritoneum. We studied Fas and FasL behaviour by evaluating the percentages of mFas and mFasL-bearing mononuclear cells from peritoneal fluid, the level of Fas and FasL gene expression at both mRNA and protein levels in the same cells, and the sFas and sFasL values in peritoneal fluid of 80 endometriotic women, at four stages of disease severity. We found no variation in percentage of mFas-bearing mononuclear cells; high and unchanging levels of Fas mRNA and protein, and high and invariable sFas values. Overproduction of sFas antagonises mFas function and plays a role as a decoy in the peritoneal fluid. The mFasL-bearing mononuclear cells and protein levels decreased from the minimal to the severe stage of disease. In contrast to FasL protein, FasL mRNA was overexpressed throughout the course of the disease. sFasL values were high and increased as the disease worsened. Our results showed a non-linear ratio between FasL mRNA and FasL protein levels. Abnormally elevated FasL mRNA may be due to dysregulation in several mechanisms controlling mRNA turnover. The high level of sFasL would be expected to down-regulate FasL activity and compete with the membrane form for mFas binding. As a consequence, mFas-bearing mononuclear cells may be unable to kill and in turn, may themselves become targets for killing by FasL-expressing endometriotic cells.

Regulation of apoptotic pathways during endometriosis: from the molecular basis to the future perspectives

PurposeEndometriosis is defined as the presence of endometrial-like endometrial cells, glands and stroma outside the uterus, causing a strong inflammatory-like microenvironment in the affected tissue. This may provoke a breakdown in the peritoneal cavity homeostasis, with the consequent processes of immune alteration, documented by peripheral mononuclear cells recruitment and secretion of inflammatory cytokines in early phases and of angiogenic and fibrogenic cytokines in the late stages of the disease. Considering the pivotal role of interaction between immune and endometriotic cells, in this paper, we aim to shed light about the role of apoptosis pathways in modulating the fine-regulated peritoneal microenvironment during endometriosis.MethodsNarrative overview, synthesizing the findings of literature retrieved from searches of computerized databases.ResultsIn normal conditions, endometriotic cells, refluxed through the fallopian tubes into the peritoneal cavity, should be attacked and removed by phagocytes and NK cells. During endometriosis, the breakdown of peritoneal homeostasis causes the failure of scavenging mechanisms, allowing the survival of endometriotic cells. The consequent so-called “immunoescaping” of endometriotic cells could be due, at least in part, to the reduction of apoptotic-mediated pathways previously described.ConclusionConsidering the large amount of evidence retrieved from in vitro as well as in vivo models, the reduced apoptosis of endometriotic cells together with the increased apoptosis of peritoneal fluid mononuclear cells may address the peritoneal homeostasis to a permissive environment for the progression of the disease.

Toll-like receptors in Alzheimer's disease: a therapeutic perspective.

Alzheimers disease (AD) is a neurodegenerative disorder mainly characterized by amyloid-β (Aβ) plaques, neurofibrillary tangles, loss of synapses and neurons and chronic neuroinflammation. Emerging data highlight the involvement of innate immunity, that has been shown to play opposing roles during the AD progression. Activated microglia and reactive astrocytes exert neuroprotection mediated through Aβ phagocytosis in the early stage, whereas, as the disease progresses, they fail in Aβ clearance and exert detrimental effects, including neuroinflammation and neurodegeneration. Specific toll-like receptors (TLRs) and coreceptors can directly or indirectly be activated to induce Aβ uptake or inflammatory responses, depending on the disease stage. Fibrillar Aβ can directly interact with TLR2, TLR4, and CD14 to induce microglial Aβ phagocytosis in the beginning stages, and neuroinflammatory responses in the late stages. Early TLR3-mediated signal enhances neuronal Aβ autophagy, although it increases neuronal apoptosis in the late AD stage. Similarly, TLR7, TLR8 and TLR9 can enhance microglial Aβ uptake in the early stage, but over time they contribute to neuroinflammation. Therefore, TLRs, and in particular TLR2 and TLR4, represent a suitable target for therapeutic intervention within the disease progression and targeting them carefully could increase Aβ autophagy and phagocytosis or reduce inflammatory responses. Several modulators with selective TLR agonist or antagonist activity have been developed, and many of them could have a therapeutic benefit in AD patients. This paper outlines the role of specific TLRs in AD, also focusing on TLR-targeted compounds yet indicated for the treatment of other inflammatory diseases, that could be used to treat the different stages of the disease.

Correlation between dioxin and endometriosis: an epigenetic route to unravel the pathogenesis of the disease

IntroductionEnvironmental toxicants can act as endocrine disrupters on the female reproductive system. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is resistant to degradation and due to its lipophilic nature, accumulates in the fat tissue and in the food chain. Human and animal exposure to TCDD affects levels of the steroid receptors and steroid-responsive gene expression and has an impact on metabolism and serum transport of steroids. Gene expression is commonly altered in endometriosis and in the eutopic endometrium of women with the disease. Aberrantly expressed genes include those associated with the regulation of transcription, proliferation, sex steroid metabolism, apoptosis, cell cycle, the immune response and cell adhesion.MethodsIn this paper, we review the evidence about TCDD’s effect on eutopic and ectopic endometrium, in order to unravel the machinery behind the dysregulation of immune and hormonal homeostasis caused by this environmental toxicant.ConclusionThe evidence collected in this review suggests that TCDD could modulate transcription at multiple levels, including the epigenetic level, and via microRNAs, thus disturbing the physiologic processes mediated through the aryl hydrocarbon receptor pathways. Exposure to TCDD also modulates the immune response by influencing the production and action of endometrial cytokines and chemokines, destroying mucosal immunity of the reproductive tract and re-directing the tissue distribution and behavior of leukocytes. Despite this large body of evidence, current human-based epidemiological studies on the association between TCDD and endometriosis remain controversial.

Behavior of Tumor Necrosis Factor-α and Tumor Necrosis Factor Receptor 1/Tumor Necrosis Factor Receptor 2 System in Mononuclear Cells Recovered From Peritoneal Fluid of Women With Endometriosis at Different Stages

During endometriosis, a breakdown occurs in endometrial and peritoneal homeostasis caused by cytokine-induced cell proliferation and dysregulation of apoptosis. We studied tumor necrosis factor (TNF)-α, TNF receptor (TNFR) 1, and TNFR2 gene expression at both messenger RNA (mRNA) and protein levels in peritoneal fluid (PF) mononuclear cells (PFMCs), the percentages of these cells bearing the same markers, and soluble TNF-α (sTNF-α) values in PF of 80 women with endometriosis. We found that TNFR1 mRNA and protein levels, the percentages of TNFR1-bearing PFMCs, and sTNF-α values decreased from minimal to severe stages of the disease. Instead, TNF-α and TNFR2 mRNA and protein levels, the percentages of membrane TNF-α (mTNF-α)- and TNFR2-bearing PFMCs increased as the disease worsened. These data allow us to hypothesize that, in early stages, the high percentages of TNFR1-bearing PFMCs and the high levels of sTNF-α could address signal toward complex I pathway, favoring the inflammatory response. With the worsening of the disease, the low percentages of TNFR1-bearing PFMCs are probably due to decreased TNFR1 mRNA transcription and protein translation rate. In early stages (minimal and mild), the percentages of both TNFR2- and mTNF-α–bearing PFMCs are so low, due to decreased mRNA transcription and protein translation rate, that subsequent cellular events may depend minimally by this interaction. The high levels of sTNF-α may be rerouted to bind TNFR1. In contrast, in the moderate and severe stages, the high percentages of TNFR2-bearing PFMCs may be saturated by high percentages of mTNF-α–bearing PFMCs, triggering death process. So, in endometriosis, each component of the TNF-α/TNFRs system may trigger opposite cellular fate.

Pleiotropic Actions of Peroxisome Proliferator-Activated Receptors (PPARs) in Dysregulated Metabolic Homeostasis, Inflammation and Cancer: Current Evidence and Future Perspectives

Background: Peroxisome proliferator-activated receptors (PPARs) have demonstrated a lot of important effects in the regulation of glucose and lipid metabolism and in the correct functioning of adipose tissue. Recently, many studies have evaluated a possible effect of PPARs on tumor cells. The purpose of this review is to describe the effects of PPARs, their action and their future prospective; Methods: Narrative review aimed to synthesize cutting-edge evidence retrieved from searches of computerized databases; Results: PPARs play a key role in metabolic diseases, which include several cardiovascular diseases, insulin resistance, type 2 diabetes, metabolic syndrome, impaired immunity and the increasing risk of cancer; in particular, PPARα and PPARβ/δ mainly enable energy combustion, while PPARγ contributes to energy storage by enhancing adipogenesis; Conclusion: PPAR agonists could represent interesting types of molecules that can treat not only metabolic diseases, but also inflammation and cancer. Additional research is needed for the identification of high-affinity, high-specificity agonists for the treatment of obesity, type 2 diabetes (T2DM) and other metabolic diseases. Further studies are needed also to elucidate the role of PPARs in cancer.

Unus pro omnibus, omnes pro uno: A novel, evidence-based, unifying theory for the pathogenesis of endometriosis

The theory of retrograde menstruation as aetiopathogenesis of endometriosis formulated by John Sampson in 1927 shows clear shortcomings: this does not explain why retrograde menstruation is a physiological process that affects 90% of women, while endometriosis occurs in only 10% of cases; it also does not explain the endometriotic foci distant from the pelvis, nor explains the cases of endometriosis in male patients. The immunological alterations of the peritoneal fluid explains the effects of disease, such as the inhibition of the physiological processes of cytolysis, but does not explain the cause. There is evidence to support the hypothesis that ectopic müllerian remnants of the endometrium, endocervix and endosalpinx are items from the genital ridge leaked during organogenesis. It is known that tissues derived from coelomatic epithelial and mesenchymal cells have the potential to metaplastically differentiate into epithelium and stroma. In addition, the phenotype of the ectopic endometrial cells is significantly different from those ectopic. There is scientific evidence that, during organogenesis, the genes of the Homeobox and Wingless family play a fundamental role in the differentiation of the ducts of Muller and development of the anatomical structure of the urogenital tract. We present here a hypothesis that deregulation of genes and the Wnt signaling pathway Wnt/β-catenin leads to aberrations and deregulation within the mesoderm, thus, may cause aberrant placement of stem cells. In addition, immune cells, adhesion molecules, extracellular matrix metalloproteinase and pro-inflammatory cytokines activate/alter peritoneal microenvironment, creating the conditions for differentiation, adhesion, proliferation and survival of ectopic endometrial cells.

Natural Killer T cell subsets in eutopic and ectopic endometrium: a fresh look to a busy corner

PurposeInvariant Natural Killer T cells (iNKT) are a specialized subset of T cells that use their T cell receptor to recognize self and foreign lipids presented by CD1d as cognate antigens. iNKT have been shown to have either protective or harmful roles in many pathological states, including microbial infection, autoimmune disease, allergic disease and cancer. Accumulating evidence seems to suggest that this unique T cell subset combines both classically innate and adaptive immunologic characteristic. Considering these recent data, the aim of work was to review the current knowledge about iNKT in eutopic and ectopic endometrium.MethodsNarrative overview, synthesizing the findings of literature retrieved from searches of computerized databases.ResultsCurrently, the immune paradigm of reproduction is gradually changing shape: recent data confirmed that cytokine milieu influences the development and plasticity of different subtype of mononuclear cells, and in turn it can be influenced by the cytokine production of the latter. Among the different NKT cell populations, the recently characterized iNKT seems to share actions typical both of innate and adaptive immunity, being capable of secreting Th1 as well as Th2 cytokine pattern. Moreover, several subtypes of iNKT were identified, who partially express the same master transcription factors of the corresponding T cells counterpart.ConclusionsAlthough the data about iNKT’s actions in eutopic and ectopic endometrium are still scarce, it is possible to hypothesize that future investigation can shed light on this point, thus allowing a better knowledge about the regulation of these two microenvironments.