Protein and Peptide Letters - Volume 25, Issue 5, 2018

Background: Assisted Reproduction Techniques (ART) have significantly advanced since the first successful In Vitro Fertilization (IVF). However, most in vitro–produced embryos fail to implant. Key steps in ART are the correct infertility diagnosis, in order to manage the individualised treatments, and the assessment of gamete and embryo viability, to identify the embryo with the best implantation potential. Objective: The goal for this manuscript was to present a brief review of proteomics in Assisted Reproduction Technologies (ART) and raises the question of whether proteomics is a good alternative for the future of ART. Methods: A literature review concerning proteomics and assisted reproduction was conducted. Results: Non-invasive approaches to correctly diagnose infertility and to access embryo development potential have the advantages of increasing our knowledge about embryo physiology, therefore allowing the development of methods to predict developmental competence and viability. These approaches include proteomic profiling and other omics technologies. Conclusion: The use of proteomics in clinical practice goes beyond the identification of the oocytes and embryos with the best developmental potentials, it may add to the diagnosis of both male and female infertility and in the future, it may be a laboratory tool that will contribute to the birth of a healthy child.

A number of tests have been proposed to assess male fertility potential, ranging from routine testing by light microscopic method for evaluating semen samples, to screening test for DNA integrity aimed to look at sperm chromatin abnormalities. Spermatozoa are an extremely differentiated cell population, having critical functions for embryo development and heredity, apart from giving haploid paternal DNA to the oocyte. Some aspects are essential to set this specific purpose. The ability of spermatozoa to perform its reproductive function takes place in the spermatogenesis, a highly specialized process depending on multiple factors with effect on male fertility. In the past 30 years, large-scale analyses of transcriptomic and proteomic analyses in mammals have generated a large amount of information on numerous biomolecules involved in spermatogenesis and male germ cell reproductive function. Sperm proteome represents the protein content that spermatozoa needs to survive and work correctly and modifications of sperm proteome play a role in determining functional changes leading to a decrease of reproductive competence into affected spermatozoa. The post-genomic approach consists of different methodologies for concurrently testicular transcriptome studies, protein compositional analysis and metabolomics findings of the spermatozoa in humans.

Background: Sertoli cell, over the past 30 years, have been elevated from simple mechanical elements to the rank of a "sentinel" in spermatogenesis. By delivering potent immunomodulatory and trophic proteins, Sertoli cells are unique cell type with a pivotal role in maintaining testis immune privilege and the immune-protection of the antigenic germ cells. Conclusions: The findings from SC transplantation studies utilizing experimental animal models of disease, demonstrate the presence of the same immuno-modulation properties and mechanisms at tissue and organ sites far from testis. The complex pathways that generate and maintain the immune tolerance involve the production of several immunomodulatory or immune-related proteins such as cytokines, chemokines, growth factors, mediators of the inflammation, complement inhibitors or adhesion molecules. A better definition and understanding of these Sertoli cell proteins and the mechanisms of immunoprotection should help to elucidate their role in the spermatogenic process. The demonstration of their capabilities in transplantation experiments suggests that Sertoli cells may be good candidates in cell therapy for a number of cell-mediated chronic diseases.

Background: Several studies demonstrate that cigarette smoking has a negative effect on the reproductive health of both genders. The mechanisms by which it alters male gonadic function are not entirely clear. The combustion of cigarette produces a lot of chemical compounds that may be responsible for the negative impact of cigarette smoke on sperm parameters. In particular, the effects on semen of nicotine, a substance present in the tobacco plant and the main constituent of cigarette smoke, have been studied, showing that this alkaloid alters sperm parameters. Recently we investigated the mechanism by which nicotine damages sperm through the evaluation of the expression of nicotinic receptors subunits in human spermatozoa. Conclusion: 8 nAChR subunits found to date in mammals are expressed in human spermatozoa but, in non-smokers subjects, only α7 subunit is translated. Cigarette smoking may stimulate the expression of some subunits, not translated in non-smokers. Therefore, the presence in sperm of other nAChR subunits than α7 could represent a marker for smoking-related sperm damage.

Background: Cervical Mucus (CM) is a viscous fluid produced by the secretory cells of the cervical crypts. The CM undergoes modifications throughout the cycle that make it have different biochemical and biophysical characteristics, becoming a crucial element for the identification of ovulation. Since CM is rich in secreted proteins, it may represent moreover a source of biomarkers for female reproductive tract diseases. Objective: This review is an attempt to collect relevant knowledge about the physicochemical properties and functions of the cervical mucus, including its important role as a clinical marker of female fertility, and draws attention to CM as a source of potential proteomic biomarkers. Findings: All the assessed studies evidenced that the observation of the CM allows the identification of the days with the highest probability of pregnancy. CM proteome changes throughout the menstrual cycle have been revealed. Few proteomic studies on the constitutive protein composition of CM of fertile women have been conducted to date. In the CM of patients affected by endometriosis have been identified some proteins that could represent potential biomarkers of the disease. Conclusion: There is still limited knowledge about the physicochemical properties and functions of the CM and how these undergo to changes during menstrual cycle. CM is a reliable predictor of fertility. Further characterization of CM proteins would contribute to a better understanding of the key role they have on fertility, reproduction and biological regulation. CM may represent moreover a source of biomarkers for gynecological diseases.

Background: Infectious etiologies contribute to 15% of male factor infertility. Enterococcus faecalis (E. faecalis) is commonly identified in semen culture of infertile men and it is associated with significantly poorer semen quality. Objective: Aim of this study was to identify new seminal biomarkers for the male tract infection by E. faecalis, using proteomic profiling, in order to understand the effect of E. faecalis on the physiopathology of male reproduction. Methods: We included in the study ten patients seeking medical care for primary infertility with prostate-vesicular-epidydimitis and with microbiological analysis on semen and/or prostatic secretions positive for E. faecalis. Ten fertile men have been enrolled as a control group in the protocol. An aliquot of each seminal plasma was subjected to an in-solution digestion protocol and analyzed using an Ultimate 3000 RSLCnano HPLC apparatus coupled to a LTQ Orbitrap Elite mass spectrometer. Results: Eight proteins have not been identified in the group of controls and have been observed in a remarkable proportion of patients, mainly involved in immune system activity (CD177, Swiprosin-1 and 2-oxoglutarate dehydrogenase). Arylsulfatase has been identified in the group of controls and was absent in all patients with infection. Three proteins (TIMP-1, WFDC domain protein 2 and Carboxypeptidase E) have been observed significantly different in patients versus controls, mainly related with inflammation. Conclusions: This is the first application of MS-based proteomics aimed to reveal an array of proteins in the seminal plasma and reflecting the effect of the infection by E. faecalis on semen composition.

Background: Recent evidences suggest that hypogonadism is an important risk factor for lower urinary tract symptoms and benign prostatic hyperplasia. Several papers have discussed the role of chronic inflammation in the development of BPH, which may be modulated by the hypogonadal state. Soluble Urokinase-type Plasminogen Activator Receptor (suPAR), known protein marker of systemic inflammation, can be assayed in the seminal plasma and represents a reliable and sensitive marker of inflammation for the Male Accessory Gland Inflammation (MAGI). Objective: The aim of this study has been to investigate if seminal suPAR is elevated in MAGI with hypogonadism and if suPAR represent a useful marker of abacterial inflammation in hypogonadism. Methods: We included in the study twenty male patients aged between 25 and 55 year-old with secondary postsurgical hypogonadism. The same patients were also evaluated after a 3-month of Testosterone Replacement Therapy (TRT), to evaluate the effect of androgen replacement therapy on suPAR. Ten fertile men have been enrolled as a control group in the protocol. SuPAR concentrations were assayed on seminal plasma using an Enzyme-Linked Immunosorbent Assay (ELISA) kit. Results: Hypogonadic patients presented significantly increased levels of seminal suPAR respect to controls (86.1±36.8 vs 55.2±20.0 ng/mL, p<0.05). TRT in hypogonadic patients has been associated with a significant reduction of suPAR levels as reported in the control group (50.9±22.91 vs 86.1±36.8 ng/ml p<0.05). Conclusions: These results confirm the role of suPAR as a protein marker of MAGI and support the hypothesis that hypogonadism induces a state of inflammation in male accessory glands which is involved in male infertility. Moreover demonstrated that testosterone treatment probably exerts a positive effect on MAGI and infertility as documented by reduction of suPAR levels in hypogonadic treated patients.

Background: Breast cancer demands safe adjuvant to overcome the side effects of standard drug tamoxifen. Diet derived bioactive compounds are reported to exhibit modulation of cancer growth leading to cell death. Chickpea is a protein rich edible legume with several bioactive compounds that includes lectin as well. Characterization of chickpea lectin for its effect against cancer cells has been investigated in this study. Method: Cicer arietinum L. lectin (CAL) agglutinating trypsin-treated rabbit blood cells was purified employing DEAE-cellulose and SP-sephadex ion exchange chromatography. The lectin was characterized for its biological activity vis-à-vis antiproliferative and apoptotic effects through cell cycle arrest in MCF-7 human breast cancer cells. Result: There is a significant inhibition of the survival of breast cancer cells due to chickpea lectin in a dose dependent manner for 24 hr. Lectin treated cells revealed distinct features of apoptosis. Flow cytometric analysis at 80 μg/ml of lectin induced S and G2 phase cell cycle arrest. CAL induced apoptosis in MCF-7 cells associated with lactate dehydrogenase leakage, cell cycle arrest and reactive oxygen species generation. Conclusion: Our studies show that chickpea lectin exerted anticancer activity and could be exploited as an essential source for medicine leading to the treatment of breast cancer.

Background: With more countries in the world entering elderly society, osteoporosis is a common disease among the elderly, especially middle-aged and elderly women. Although calcitonin is an effective drug used to treat osteoporosis in clinical practice, it also exists such problems as high cost, short half-life, and high immunogenicity. Therefore, to explore more efficient calcitonin has important clinical significance. Objective: Given the emergence of new-generation gene sequencing, numerous genome sequences of marine species have been revealed. This study aimed to identify new, highly active Calcitonins (CTs) from the gene database. Methods: Candidate CT sequences were obtained by BLAST and analyzed. The evolutionary tree of these sequences was constructed using the Neighbor-Joining method of MEGA 7 software. Secondary structures were analyzed by Circular Dichroism (CD). The biological activities of CTs were estimated using the standard of the rat hypocalcemic activity assay in vivo. The half-life and immunogenicity of CT sequences were determined by ELISA. The physicochemical properties of peptides were analyzed with ProtParam and HeliQuest. Results: A total of 64 candidate CT gene and amino acid sequences from different species were obtained by BLAST using the salmon CT (sCT) sequence as the query sequence. These sequences were clustered to 27 different CT polypeptide sequences, and then the evolutionary tree was constructed. A total of 13 sequences were selected for chemical synthesis and activity assay. Results showed that although their secondary structures were similar, four types of candidate CTs had 30% higher activities than sCT, three other types had similar activities to sCT, and the remaining four types had much lower activities than sCT. Among the three designed CTs, the activities of CT-01 and CT-02 were at least 50% higher than those of sCT. Furthermore, all three CT sequences had a similar half-life to sCT and lower immunogenicity. Conclusion: CTs from Monodelphis domestica, Gallus gallus, Ornithorhynchus anatinus, and Carassius auratus had high activities. The exploration and mining of the marine-life genome database can be extremely valuable considering broad application prospect.