**2. Peritoneal fluid and/or serum markers**

Many serum and peritoneal fluid markers can be used to discriminate between patients with or without endometriosis (Table 2). Using markers with a high degree of sensitivity and specificity for endometriosis it is possible the development of peritoneal fluid and /or serum based diagnostics tools, therapeutic strategies and prognosis markers.


Table 2. Peritoneal fluid (PF) and/or serum markers for endometriosis


Table 2. Peritoneal fluid (PF) and/or serum markers for endometriosis. (Continuation)

#### **2.1 Glycoproteins**

420 Endometriosis - Basic Concepts and Current Research Trends

For a clinical purpose, the identification of highly sensitive and specific diagnostic test of endometriosis should facilitate the development of accurate and non-invasive test diagnosis

ENDOMETRIAL MARKERS Cell adhesion molecules (CAMs)

serum based diagnostics tools, therapeutic strategies and prognosis markers.

GROWTH FACTORS Hepatocyte growth factor (SF/HGF)

GENETIC MARKERS Survivin gene expression

Glycoproteins Growth factors Cytokines Autoantibodies Hormones

Proteolytic enzymes and their inhibitors

Soluble adhesion molecules Environmental contaminant

Proteolytic enzymes

Aromatase P450 Hormone receptors

p53 mutations Polymorphisms

Many serum and peritoneal fluid markers can be used to discriminate between patients with or without endometriosis (Table 2). Using markers with a high degree of sensitivity and specificity for endometriosis it is possible the development of peritoneal fluid and /or

CA19-9

IL-1 IL-6 IL-8

Table 2. Peritoneal fluid (PF) and/or serum markers for endometriosis

Interferon-γ

Fibroblast growth factor (FGF) Epidermal growth factor (EGF)

Insulin-like growth factor I (IGF-I)

Transforming growth factor-alpha (TGF-α) Transforming growth factor-beta (TGF-β) Vascular endothelial growth factor (VEGF) Epidermal growth factor receptor (EGF-R)

Monocyte chemoattractant protein (MCP)-1

and prognosis.

SERUM MARKERS

ENDOMETRIAL TISSUE BIOCHEMICAL MARKERS

Table 1. Markers for endometriosis

**2. Peritoneal fluid and/or serum markers** 

GLYCOPROTEINS CA125

CYTOKINES TNF-α

PERITONEAL FLUID AND/OR

Some serum glycoproteins, more commonly known for its use in the diagnosis or monitoring of cancers, might also serve as a marker for endometriosis, although levels are usually elevated only in advanced stages and are therefore not suitable for routine screening.

### **2.1.1 CA125**

CA125 is a 200,000 Da glycoprotein expressed on the surface of the coelomic epithelium, including the epithelium of the endocervix, endometrium, fallopian tube, pelvic peritoneum and placental tissues. Serum CA125 levels increase in patients with malignant and benign gynaecologic diseases, including endometriosis.

Despite the most important clinical use of CA125 is the monitoring of patients with ovarian cancer, high levels can be found in women with endometriosis. Many studies have assessed the role of CA125 serum levels in women affected with endometriosis. The sensitivity and specificity of serum CA125 assay varies with the stage of disease. Usually, high CA125 serum levels can be found both in most patients with advanced endometriosis and in few patients with early-stage disease. Therefore, the routine use of serum CA125 cannot be used as a diagnostic tool for endometriosis. Serum CA125 may be more useful in evaluating recurrent disease or the outcome of a surgical treatment. CA125 levels may also be useful in patients with advanced endometriosis and several studies have suggested the use of this marker in the preoperative diagnosis of endometriosis.

The patients with endometriosis often undergo repeated laparoscopic examinations to assess the progress during and after therapy or to determine the recurrence of disease. Therefore, CA125 may be useful in the management of endometriosis and some authors

Current Insights and Future Advances in Endometriosis Diagnostics 423

Elevated serum levels of *Epidermal Growth Factor Receptor (EGF-R),* involved in angiogenesis, suggest an active role for EGF in the development of endometriosis (Matalliotakis et al.,

*Insulin-like Growth Factor I (IGF-I)* serum levels in patients with early stage endometriosis, and in healthy control, were significantly lower than the levels in patients with late stage endometriosis, suggesting that IGF-I is an important mediator in the development and/or maintenance of endometriosis or progression to late stage disease (Gurgan et al., 1999).

Many studies report that angiogenesis is probably involved in the pathogenesis of endometriosis. *Vascular endothelial growth factor (VEGF)*, also known as vascular permeability factor, is one of the most potent and specific angiogenic factors. VEGF has emerged as an

VEGF levels in both peritoneal fluid and serum were higher in women with endometriosis compared with controls. The cellular source of VEGF in peritoneal fluid has not yet been precisely defined. Some evidence suggests that the endometriotic lesions themselves produce this factor and that the activated peritoneal macrophages are able to synthesize and

The immune system plays an important role in the pathogenesis of endometriosis, which begins, therefore, to be treated as an autoimmune disease. T-helper, T-suppressor and natural killer (NK) cells concentrations are altered in serum and peritoneal fluid of patients with endometriosis (Lebovic et al., 2001; Nothnick, 2001). In addition, IgG and IgA antiendometrial antibodies have been detected in the sera and vaginal and cervical secretions of endometriosis patients. The presence of anti-phospholipids and anti-histones antibodies has been documented by some authors and questioned by others. These observations would believe that markers of immune reactivity, particularly cytokines, might be used as a

Macrophages are a major source of many cytokines involved in immune response, haematopoiesis, inflammation and many other homeostatic processes. Upon stimulation by microorganisms, microbial products or endogenous factors including cytokines, macrophages can *de novo* synthesize and release a large variety of cytokines (i.e. IL-1, IL-1ra, IL-6, IL-8, IL-10, IL-12, TNF-α, IFN-α, IFN-γ, MCP-1, MCP-3, MIF, M-CSF, G-CSF, GM-CSF, MIP-1, MIP-2, LIF, OSM, TGF-β). Some cytokines can up-regulate the production of cytokines by macrophages (IL-3, GM-CSF, IFN-γ) while others can inhibit it (IL-4, IL-10, IL-13, TGF-β). In addition, these cytokines can modulate most of the macrophage functions and cell surface marker expression. Other cytokines (chemokines such as MCP-1, 2, 3, MIP-1,2

and RANTES) contribute to the recruitment of circulating monocytes within tissues.

T lymphocytes are important regulatory cells that secrete several cytokines and participate actively in this inflammatory response. According to the pattern of cytokines secreted, the immune response is classified as cytotoxic or type 1 (IFN-γ, IL-2, IL-12) and humoral or type

important regulator of normal angiogenesis and pathological neovascularisation.

secrete VEGF (Matalliotakis et al., 2003a, 2003b).

2 (IL-4, IL-5, IL-10 and IL-13) *(*Barcelò et al., 2006).

**2.3 Immunological markers** 

diagnostic aid for endometriosis.

**2.3.1 Cytokines** 

2003a, 2003b).

suggest its assessment in women with suspected endometriosis, in association with laparoscopy and biopsy. In addition, in literature was reported that measurement of serum CA125 levels might be useful in identifying patients with infertility that may have severe endometriosis and could benefit from early surgical treatment.

CA125 levels were assessed in the PF of patients with and without endometriosis. Although levels of CA125 in the PF were almost 10 times higher than serum levels, no differences were found between women with and without endometriosis. In addition, CA125 levels are measured also in other body fluids, such as menstrual discharge and the uterine fluid, but are not useful in clinical practice.

## **2.1.2 CA19-9**

CA19-9 is a high-molecular-weight glycoprotein that was initially thought to be an oncofetal antigen. Serum CA19-9 levels were elevated in patients with some malignant tumour, such as gastrointestinal adenocarcinoma, pancreatic carcinoma, or lung carcinoma; thus, the measurement of serum CA19-9 levels is useful in the diagnosis of these tumours. In gynaecology, the serum CA19-9 levels are elevated in patients with malignant and benign ovarian tumours. Furthermore, a case of an ovarian chocolate cyst with a markedly elevated serum CA19-9 level has been reported. In addition, it has been reported that serum CA19-9 levels in women with endometriosis are significantly reduced during therapy compared with the basal levels before treatment. Serum CA19-9 levels in patients with endometriosis are significantly higher than those in patients without endometriosis and that serum CA19-9 levels increase in accordance with the advancement of the clinical stage of endometriosis. CA19-9 was also detected in the endometrial glandular epithelium in ovarian chocolate cysts by immunohistochemistry. These results reveal that the measurement of the serum CA19-9 levels, as well as the serum CA125 level, may prove to be a valuable tool for predicting the severity of endometriosis as diagnosed by laparoscopy.

## **2.2 Growth factors**

The endometrium in endometriosis behaves like tumorous tissue and the growth factors involved in tumour proliferation, angiogenesis and invasiveness have been investigated for their expression in endometriosis. Indeed, the degree of endometriosis is positively correlated with the concentration in peritoneal fluid and serum of *Hepatocyte Growth Factor/Scatter Factor (HGF/SF*), a multifunctional polypeptide that has been implicated in embryo development, tissue repair, and cancer growth, produced mainly by mesenchymal cells with activity mediated through the c-met receptor found principally on epithelial and endothelial cells (Zong et al., 2003).

Inflammatory macrophages and the inflammatory mediators they release could be related to the ectopic implantation of endometriosis: *Fibroblast Growth Factor (FGF), Epidermal Growth Factor (EGF), Transforming Growth Factor-alpha (TGF*α*), Transforming Growth Factor-beta (TGF*β*) and Tumor Necrosis Factor-alpha (TNF* α*).* It is been shown that these growth factors stimulate in vitro proliferation of endometrial stromal cells, suggesting that they could improve the implantation of endometrial cells.

Elevated serum levels of *Epidermal Growth Factor Receptor (EGF-R),* involved in angiogenesis, suggest an active role for EGF in the development of endometriosis (Matalliotakis et al., 2003a, 2003b).

*Insulin-like Growth Factor I (IGF-I)* serum levels in patients with early stage endometriosis, and in healthy control, were significantly lower than the levels in patients with late stage endometriosis, suggesting that IGF-I is an important mediator in the development and/or maintenance of endometriosis or progression to late stage disease (Gurgan et al., 1999).

Many studies report that angiogenesis is probably involved in the pathogenesis of endometriosis. *Vascular endothelial growth factor (VEGF)*, also known as vascular permeability factor, is one of the most potent and specific angiogenic factors. VEGF has emerged as an important regulator of normal angiogenesis and pathological neovascularisation.

VEGF levels in both peritoneal fluid and serum were higher in women with endometriosis compared with controls. The cellular source of VEGF in peritoneal fluid has not yet been precisely defined. Some evidence suggests that the endometriotic lesions themselves produce this factor and that the activated peritoneal macrophages are able to synthesize and secrete VEGF (Matalliotakis et al., 2003a, 2003b).
