Angiotensin I-converting enzyme and potential substrates in human testis and testicular tumours

Localization and Distribution of Testicular Angiotensin I Converting Enzyme (ACE) in Neck and Mid-Piece of Spermatozoa from Infertile Men in Relation to Sperm Motility

Testicular angiotensin converting enzyme (ACE) is known to play an essential role in the male reproduction and fertility. Data about tACE in cases of male infertility are quite scarce, and in this respect we aimed to study localization and distribution of tACE protein in the neck and mid-piece of spermatozoa from pathological samples in relation to sperm motility. The enzyme expression during capacitation and acrosome reaction was quantitatively assessed. In human ejaculated spermatozoa tACE is localized on sperm plasma membrane of the head, the neck and mid-piece of the tail. The immunoreactivity becomes stronger in capacitated spermatozoa followed by a decrease in acrosome reacted sperm. In different cases of semen pathology (oligozoospermia, asthenozoospermia and teratozoospermia) fluorescent signals in the neck and mid-piece are in punctate manner whereas in normozoospermia they were uniformly distributed. The expression area of tACE the neck and mid-piece was decreased in ejaculated and capacitated sperm from pathological semen samples compared to normospermia. Significant positive correlation was established between tACE area and progressive sperm motility, whereas with immotile sperm the correlation was negative. Our data suggest that proper distribution of tACE in the neck and mid-piece is required for normal sperm motility that could be used as a novel biomarker for male infertility.

The tACE/Angiotensin (1-7)/Mas Axis Protects Against Testicular Ischemia Reperfusion Injury

OBJECTIVE

To investigate whether exogenous angiotensin (Ang)-(1-7) administration can protect against the damaging consequences of testicular ischemia reperfusion (tIR) injury.

MATERIALS AND METHODS

Eighteen male Sprague-Dawley rats were divided equally among the following 3 groups: sham, unilateral tIR injury (1 hour of ischemic treatment and 4 hours of reperfusion), and tIR + Ang-(1-7) (0.3 mg/kg). Testicular tissues obtained from the rats were evaluated for the expression of testicular angiotensin-converting enzyme (tACE), Ang-(1-7), and the Ang-(1-7)-specific receptor Mas by immunohistochemistry and enzyme-linked immunosorbent assay. Reduced spermatogenesis, induction of the caspase-8 pathway, and nitric oxide (NO) generation were assessed. The effects of tIR and Ang-(1-7) treatment on the PI3K/Akt antiapoptosis pathway were also investigated.

RESULTS

Testicular morphological changes and reduced spermatogenesis associated with decreased expression of the tACE/Ang-(1-7)/Mas axis were observed during tIR. These effects were also accompanied by increased activity of caspase-3 and -8, downregulation of the survivin and BAD transcripts, and decreased NO formation. During tIR, PTEN expression was increased, leading to inactivation of the PI3K/Akt pathway. Acute treatment with Ang-(1-7) prior to reperfusion attenuated the tIR-induced damage described above.

CONCLUSION

Expression of the tACE/Ang-(1-7)/Mas axis was downregulated during tIR. Administration of exogenous Ang-(1-7) prior to reperfusion rescued tACE and Mas expression and protected against germ cell apoptosis and oxidative stress. Increased NO generation and activation of the PI3K/Akt signaling pathway may have partially contributed to these effects. The tACE/Ang-(1-7)/Mas axis likely plays a role in the maintenance of normal testis physiology and spermatogenesis.

Angiotensin-converting enzymes play a dominant role in fertility

According to the World Health Organization, infertility, associated with metabolic syndrome, has become a global issue with a 10%-20% incidence worldwide. An accumulating body of evidence has shown that the renin-angiotensin system is involved in the fertility problems observed in some populations. Moreover, alterations in the expression of angiotensin-converting enzyme-1, angiotensin-converting enzyme-2, and angiotensin-converting enzyme-3 might be one of the most important mechanisms underlying both female and male infertility. However, as a pseudogene in humans, further studies are needed to explore whether the abnormal angiotensin-converting enzyme-3 gene could result in the problems of human reproduction. In this review, the relationship between angiotensin-converting enzymes and fertile ability is summarized, and a new procedure for the treatment of infertility is discussed.

Histological and immunohistochemical studies on the epididymal duct in the dromedary camel (Camelus dromedarius)

This study was conducted to underscore the spatial distribution of some biologically active proteins within the epididymal duct in the dromedary camel. Paraffin-embedded sections from different regions of epididymis were stained by conventional histological techniques and by immunohistochemistry. A battery of primary antibodies against six proteins (S100, alpha smooth muscle actin [α-SMA], connexin-43 [Cx43], galactosyltransferase [GalTase], angiotensin converting enzyme [ACE], and vascular endothelial growth factor [VEGF]) were used. The epididymal epithelium consisted of five cell populations: principal, basal, apical, dark, and halo cells. The histochemical findings indicated the absence of binding sites for VEGF and Cx43. The principal cells (PCs) showed variable immunoreactivity (IR) for ACE, S100, and GalTase throughout the whole length of the duct. The apical surfaces of most PCs (at the caput) and some PCs (at the corpus) exhibited intense ACE-IR, whereas those at the cauda displayed alternating negative and strong immunostaining. Similarly, moderate S100-IR was found in cytoplasm and nuclei of all PCs at the caput, few PCs at the corpus, and several PCs alternating with negative PCs at the cauda. In contrast, only some PCs showed weak to strong GalTase-IR in different regions. Apart from negative to weak positive S100-IR, basal cells failed to show IR for all other proteins. Apical cells displayed strong IR for ACE, S100, and GalTase with some regional differences. The peritubular and vascular smooth muscle cells revealed strong α-SMA-IR in all regions. In conclusion, the spatial distribution of different proteins in camel epididymis showed similarities and differences to other mammalian species. The region-specific topographic distribution of different proteins and cell types might indicate that the caput and cauda are metabolically more active than that of the corpus.

Immunohistochemical studies of the epididymal duct in Egyptian water buffalo (Bubalus bubalis)

Using immunohistochemistry (IHC), this study aimed to evaluate the regional distribution pattern of some biologically active proteins in the epididymis of Egyptian water buffalo and to determine the structural-functional relationships of the different epididymal structures. Wax-embedded sections from different regions of the epididymal duct from adult, clinically healthy, buffalo bulls were used. Primary antibodies against angiotensin converting enzyme (ACE), S-100, galactosyltransferase (GalTase), alpha smooth muscle actin (α-SMA), connexin 43 (Cx43) and vascular endothelial growth factor (VEGF) were used for immunohistochemical studies. The results showed that, in addition to the well-known principal and basal cells, the epididymal epithelium, similar to that of other species, possessed apical cells and intraepithelial leukocytes. IHC showed that, with the exception of VEGF which reacted negatively, all antibodies used displayed variable reactivity in the different epididymal structures. Apical cells expressed a strong reaction with ACE along the entire length of the duct. The principal cells in the caput epididymis exhibited a distinct reactivity with S-100 and GalTase. The peritubular muscular coat displayed a marked immunostaining for α-SMA and for Cx43. In conclusion these findings showed a regional-specific distribution pattern, distinct from that in bovine bulls. Some potential functional capacities, especially absorptive and secretory ones, are discussed in relation to the different epididymal regions.

Pathology of germ cell tumors of the testis

BACKGROUND

An increasing incidence of testis tumors has been noted over the second half of the 20th century. Congenital malformation of the male genitalia, prenatal risk factors, nonspecific and specific exposures in adulthood, and male infertility have all been associated with the etiology of germ cell tumors.

METHODS

The histologic classification, pathology, and current concepts of testicular germ cell tumors are reviewed.

RESULTS

Germ cell tumors occur at all ages. The tumors are identified as pure form (those of one histologic type) and mixed form (more than one histologic type). Over half of germ cell tumors consist of more than one cell type, requiring appropriate sampling for the correct diagnosis and correlation with the serum tumor markers. Burned-out germ cell tumors may occur in patients with metastatic disease with no gross evidence of a testicular tumor.

CONCLUSIONS

Appropriate management of testis tumors relies on accurate pathology and classification of these tumors.

Complete recovery after the removal of an ectopic testicle in a case of primary reninism and retroperitoneal hemangioma

A 32-year-old man recovered completely from hypokalemic hypertension that had been caused by primary reninism after the ablation of an ectopic left testis, epididymis and ductus deferens. For several years, severe hypertension has been resistant to treatment, even the concurrent administration of up to seven antihypertensive agents. In this case, cryptorchidism was associated with an indirect inguinal hernia and an open peritoneo-vaginal process on both sides, aplasia of the posterior wall of the inguinal canal on the right side, an umbilical hernia, and a retroperitoneal tendrillar hemangioma.

Quantitative study of testicular angiotensin-converting enzyme on the surface of human spermatozoa

Expression of testicular angiotensin-converting enzyme on the surface of human spermatozoa was studied by means of flow cytometry with monoclonal antibodies. Expression of testicular angiotensin-converting enzyme on the cell surface depended on functional and morphological characteristics of spermatozoa.

Testicular Isoform of Angiotensin I-Converting Enzyme (ACE, CD143) on the Surface of Human Spermatozoa: Revelation and Quantification Using Monoclonal Antibodies

PROBLEM

The elucidation of the role of angiotensin-converting enzyme (ACE, CD143) in the male fertility has been hampered by the absence of highly specific antibodies to the native testicular isoform (tACE). The quantification of tACE expression on human-ejaculated spermatozoa was performed using a novel panel of monoclonal antibodies (mAbs).

METHOD OF STUDY

The expression of tACE on the surface of live and fixed human spermatozoa was analyzed by flow cytometry and immunocytochemistry using new mAbs to human tACE.

RESULTS

Monoclonal antibodies 1E10 and 4E3 similarly revealed tACE on the surface of live and fixed spermatozoa. The high percentage of tACE-positive spermatozoa (median 81%) was revealed in the swim-up fraction of sperm. Antibody-induced tACE shedding occurs preferentially from live sperm with defective function and/or morphology. Testicular ACE is located on the plasma membrane of the post-acrosomal region, the neck and midpiece of normal spermatozoa, but showed a variable distribution on the defective cells.

CONCLUSIONS

The new mAbs recognizing the C-terminal domain of human ACE are useful tools for quantification of tACE expression on human live and fixed spermatozoa and further adequate analysis of the tACE role in reproduction.

Cardiovascular-related proteins identified in human plasma by the HUPO Plasma Proteome Project pilot phase

Proteomic profiling of accessible bodily fluids, such as plasma, has the potential to accelerate biomarker/biosignature development for human diseases. The HUPO Plasma Proteome Project pilot phase examined human plasma with distinct proteomic approaches across multiple laboratories worldwide. Through this effort, we confidently identified 3020 proteins, each requiring a minimum of two high-scoring MS/MS spectra. A critical step subsequent to protein identification is functional annotation, in particular with regard to organ systems and disease. Performing exhaustive literature searches, we have manually annotated a subset of these 3020 proteins that have cardiovascular-related functions on the basis of an existing body of published information. These cardiovascular-related proteins can be organized into eight groups: markers of inflammation and/or cardiovascular disease, vascular and coagulation, signaling, growth and differentiation, cytoskeletal, transcription factors, channels/receptors and heart failure and remodeling. In addition, analysis of the peptide per protein ratio for MS/MS identification reveals group-specific trends. These findings serve as a resource to interrogate the functions of plasma proteins, and moreover, the list of cardiovascular-related proteins in plasma constitutes a baseline proteomic blueprint for the future development of biosignatures for diseases such as myocardial ischemia and atherosclerosis.

[Angiotensin converting enzyme (ACE, CD143) in the regular pulmonary vasculature]

Angiotensin I converting enzyme (ACE, CD143) is an endothelial transmembrane Zn2+-dipeptidylpeptidase. By formation of angiotensin II and degrading bradykinin it acts as a vasoconstrictor. We examined endothelial ACE expression in human pulmonary vessels in specimens from 20 female and 19 male patients (age: 34-76 years) by immunohistochemistry. In all specimens, capillary endothelial cells showed the strongest expression, followed by those in arterioles and arteries. Venules and veins showed next to no staining. The differences in staining intensities were significant ( P<0.001). Sex affected neither the expression intensity nor the expression pattern. Summarizing, we demonstrate the existence of a vessel-type specific ACE expression pattern for pulmonary vessels. The nearly exclusive endothelial ACE expression in capillaries and arterial vessels points to ACE as an immunohistochemical marker for these vessels in normal lung tissue.

The emerging phenotype of the testicular carcinoma in situ germ cell

This review summarises the existing knowledge on the phenotype of the carcinoma in situ (CIS) cell. CIS is a common pre-invasive precursor of testicular germ cell tumours of adolescents and young adults. These tumours display a variety of histological forms. Classical seminoma proliferates along the germ cell lineage, whereas embryonal carcinoma retains embryonic features and readily differentiates into teratomas that resemble various somatic cell lineages. A thorough review of the gene expression in CIS cells in comparison to normal testicular germ cells and overt tumours supports the view that CIS is a common precursor for both tumour types. Impaired cell differentiation resulting in a partial retention of the embryonic features, associated with an increasing genomic instability may be responsible for a remarkable phenotypic heterogeneity of CIS cells. Depending on the degree of differentiation and pluripotency, CIS cells found in adult patients seem to be predestined for further malignant progression into one or the other of the two main types of overt tumours. A new concept of phenotypic continuity of differentiation of germ cells along germinal lineage with a gradual loss of embryonic features based on the analysis of gene expression in all types of germ cells during their ontogeny is presented in this review. The data point out that despite the phenotypic continuum of gene expression, there are two periods of rapid changes of gene expression: first at the transition from primordial germ cells to pre-spermatogonia, and later during the pubertal switch from the mitotic to meiotic cell division. The persistent expression of embryonic traits in CIS cells, and the high expression of the cell cycle regulators that are typical of mitotic germ cells support our long-standing hypothesis that CIS cells originate from primordial germ cells or gonocytes and not from germ cells in the adult testis.

Current views on the pathogenesis of testicular germ cell tumours and perspectives for future research: highlights of the 5th Copenhagen Workshop on Carcinoma in situ and Cancer of the Testis

This review article highlights the most important contributions presented at the 5th Copenhagen Workshop on Carcinoma in situ and Cancer of the Testis, which was held in Denmark, August 29-31, 2002. The major themes that emerged at the meeting are critically discussed and perspectives for future research in this field are presented.