**4. Applications and experiences in the past**

The 2-DE for tissue sample is more complex than that for serum. Tissue from ovarian chocolate cysts or from eutopic endometrium contains connective tissues, red blood cells, epithelial cells and stromal cells. Stringent protocols are adopted to ensure uniformity throughout the process to facilitate the protein maps. However, the development of robust assay platforms and standardized protocols are required before MS-based antigen profiling can be performed in the clinical setting.

**29**

*Proteomics Research and Its Possibility of Application in Endometriosis*

aforementioned results can be used as diagnostic markers for EMs.

Ferrero et al. [89] used two-dimensional gel electrophoresis, silver stained, semiquantitative computerized analysis the changes of protein expression profile in the peritoneal fluid and plasma of 72 patients with EMs and 35 infertile control patients. Compared with the controls, one beta chain isoform (HpbetaE; molecular weight 38.40 ± 0.94 kD; and isoelectric point, 5.63 ± 0.17) had significantly higher expression in women with endometriosis. HpbetaE level was found no significant difference between mild endometriosis (rAFS, stage I-II) and severe endometriosis (rAFS, stage III-IV). But the expression of HpbetaE in the control group was obtained to be related to the stage of menstrual cycle. The above studies indicate that changes in the protein expression profile of patients with endometriosis. In 2007, Liu et al. [90] used SELD I-TOF-MS technology and its associated protein chip to detect the plasma protein profiles from 36 patients of endometriosis and 35 healthy individuals. 21 differentially expressed protein peaks were found and three protein peaks were established. The endometriosis diagnostic model had a sensitivity of 91.7% and a specificity of 82.9%, and was performed on 16 healthy subjects and 15 patients. The sensitivity was 87.5% and the specificity was 80%. It provides an approach for screening the plasma markers of endometriosis. In 2007, Ferrero et al. [91] used two-dimensional gel electrophoresis; protein spots of interest were identified by liquid chromatography tandem mass spectrometry to study the differential expression of peritoneal fluid proteins in patients with and without endometriosis. Several molecules had aberrant expression in peritoneal fluid of women with endometriosis

may be useful for a better understanding of the pathogenesis of this disease.

In 2006, Zhang et al. [92] applied two-dimensional gel electrophoresis (2-DE), Western blotting, and mass spectrometry (MS) technology to study proteins in endometriosis and normal controls, and analyzed differences using Western blots. The normal human serum and patient serum were compared with the total protein of endometriosis. In patients with endometriosis, 13 protein spots were associated with 11 known proteins, while 11 protein spots were found differently expressed in the endometrium of patients with and without endometriosis. Some proteins may be cytoskeleton, some may regulate in cell cycle, signal transduction or immune function participation. The hybridization of vimentin, beta-actin and ATP synthase beta subunit in serum of patients with endometriosis was significantly different from that of normal serum. Three different points were used to determine the protein expression profile, vimentin, β-actin, and ATP synthase β subunits respectively.

**4.1 Expression and significance of peritoneal fluid protein in patients** 

In 2003, Tabibzadeh et al. [88] used two-dimensional gel electrophoresis to analyze the protein profile of peritoneal fluid in 12 patients with EMs (6 cases were mild and 6 cases were severe degree). However, 12 cases of non-EMs ascites were analyzed as control (6 cases of infertility, 6 cases of normal fertile). There was no significant difference between the infertile controls and the normal fertile control group. However, the patients with mild EMs had protein reductions associated with several peritoneal protein spots of approximate molecular weights of 35–40 kD and pI close to 5.7–6.0. and the reduction in severe EMs cases was more markedly apparent. Consistent with these data, enzyme-linked immunosorbent assay showed that severe endometriosis was associated with markedly elevated levels of IL-10 in the peritoneal fluid. Endometriosis maybe associated with disturbed secretion of proteins into the peritoneal cavity and with an elevated level of IL-10 in the peritoneal fluid. Most of these proteins have not been further described in the existing literatures, so it is still unclear whether the

*DOI: http://dx.doi.org/10.5772/intechopen.81850*

**with endometriosis**

*Molecular Bases of Endometriosis - The Integration Between Research and Clinical Practice*

analyzed by peptide fingerprinting or sequence tags method.

*3.2.3 Surface-enhanced laser desorption/ionization (SELDI-MS)*

*3.2.1 Isotope-coded affinity tagging multidimensional LC-MS*

*3.2.2 MALDI-MS*

single spot for 2-DE gel.

of a single target [86, 87].

**4. Applications and experiences in the past**

immunogenic proteins, the corresponding spots are separated from the gel and gels were digested. MS or tandem mass spectrometry is used for analysis and then

LC–MS makes identification and quantification of target protein possible in a large and complex sample and most of the time it may not be achieved in the clinical work. However, it will be useful when proteins are limited in a sample and at pres-

Antigen analysis of immunocapture MS is derived from the immobilization of antibodies in the serum of patients. Almost all antibodies are captured on protein A or G, which is a bacterial derived protein with specific affinity for the Fc domain of the antibody. Protein mixtures (cell or tissue lysates) are applied to a column or bead immobilized with antibodies to capture specific antigens of antibodies present in patient samples. Finally, the proteins were identified by MALDI-TOF-MS or surface enhanced laser desorption/ionization mass spectrometry (SELDI-MS). In SELDI-MS, the protein is enzymatically cleaved into a peptide mixture and undergoes MS. It can be a fully automated system allowing high-throughput and rapid identification. MS afford a method to identify a protein even from a complex mixture of proteins [81, 82]. It is preferred and an applicable for a pure protein or a

Chemical defined or antibodies-coated protein biochip arrays for rapid protein detection. This system is used when small amount of samples is available. Very high surface expression of the immunoglobulin binding protein (proACTR) as the antigen capture and transfer reagent [83]. ProACTR can immobilize the antibody through the Fc region of antibody, and allows for higher capture capacity than antibody-coated beads. Captured antigens can be directly transferred to a platform for MS analysis (SELDI-TOF-MS). It starts its diagnosis research with post-translationally modified proteins and high-throughput technique in breast cancer, lung cancer and prostate cancer. Unfortunately, it does not allow reliable protein sometimes [84, 85]. To the best of our knowledge, immunoproteomics with proACTR has not yet been applied to profile antigens associated with a certain disease, but mainly to the quantification

The 2-DE for tissue sample is more complex than that for serum. Tissue from ovarian chocolate cysts or from eutopic endometrium contains connective tissues, red blood cells, epithelial cells and stromal cells. Stringent protocols are adopted to ensure uniformity throughout the process to facilitate the protein maps. However, the development of robust assay platforms and standardized protocols are required before MS-based antigen profiling can be performed in the

ent this method will be considered as a supplement to 2-DE gel [79, 80].

**28**

clinical setting.
