European Journal of Histochemistry 2010; volume 54:e43 Immunoreactivity of thymosin beta 4 in human foetal and adult genitourinary tract S. Nemolato,1 T. Cabras,2 M.U. Fanari,1 F. Cau,1 D. Fanni,1 C. Gerosa,1 B. Manconi,2 I. Messana,2 M. Castagnola,3 G. Faa1 1Dipartimento di Citomorfologia, Divisione di Anatomia Patologica, University of Cagliari, Cagliari, Italy; 2Dipartimento di Scienze Applicate ai Biosistemi, Università di Cagliari, Cagliari, Italy; 3Istituto di Biochimica e di Biochimica Clinica, Università Cattolica Roma, Italy Abstract Thymosin beta 4 (Tβ4) is a member of the beta-thymosins family, a family of peptides playing essential roles in many cellular func- tions. Our recent studies suggested Tβ4 plays a key role in the development of human salivary glands and the gastrointestinal tract. The aim of this study was to analyse the presence of Tβ4 in the human adult and foetal genitourinary tract. Immunolocalization of Tβ4 was studied in autoptic samples of kidney, bladder, uterus, ovary, testicle and prostate obtained from four human foetuses and four adults. Presence of the peptide was observed in cells of different origin: in surface epithelium, in gland epithe- lial cells and in the interstitial cells. Tβ4 was mainly found in adult and foetal bladder in the transitional epithelial cells; in the adult endometrium, glands and stromal cells were immunoreactive for the peptide; Tβ4 was main- ly localized in the glands of foetal prostate while, in the adults a weak Tβ4 reactivity was restricted to the stroma. In adult and foetal kid- ney, Tβ4 reactivity was restricted to ducts and tubules with completely spared glomeruli; a weak positivity was observed in adult and foetal oocytes; immunoreactivity was mainly localized in the interstitial cells of foetal and adult testis. In this study, we confirm that Tβ4 could play a relevant role during human devel- opment, even in the genitourinary tract, and reveal that immunoreactivity for this peptide may change during postnatal and adult life. Introduction Beta-thymosins are N-terminally acetylated peptides of 5 kDa molecular mass, which are composed of 40-44 amino acid residues.1 Thymosyn β4 (Tβ4) is a 43-aminoacid peptide, first isolated in human blood platelets;2 it is probably an important intracellular modulator of actin polymerization3 due to its capacity to interact with monomeric actin.1 As an extracel- lular factor, Tβ4 has been documented to be involved in hormonal activities and in modu- lating the immune response.1,4 It has also been found to have anti-inflammatory efficacy5 and to be implicated in cardiac protection,6 angio- genesis,7 wound healing,8 blood coagulation,2 hair growth and apoptosis.1,4 Recently, a role for Tβ4 has been described in developing foetal salivary glands,9 in coro- nary vasculogenesis,10 and during the develop- ment of different neural cell types in rat brains.11 In mouse embryonic kidneys, Tβ4 activity has been shown to increase during development, remaining at high levels during active nephrogenesis.12 In rat foetal kidneys, Tβ4 has been identified in differentiating glomeruli, while in adult rats it has been mainly found in collecting ducts.12,13 High lev- els of Tβ4 mRNA were detected in normal human embryonic kidneys and in renal tumors.14 Recent studies have also provided new information concerning a role for Tβ4 in human glomerulosclerosis and in kidney fibrosis in adults.15 Tβ4 also plays an important role in the development of the reproductive system. Its secretion has been shown to be modulated by testosterone and gonadotropin in mice and pigs.16-18 Increased levels of Tβ4 in the rat ovary have been correlated with the process of luteinization16 under the influence of human chorionic gonadotropin, which stim- ulates Tβ4 gene expression.17 The Tβ4 gene is downregulated at transcriptional level by androgen activity in prostate cancer cell cul- ture.19 Presence of Tβ4 has been reported dur- ing the formation of actin-based pseudopodia in tumoral cells, facilitating cell migration and prostate cancer progression.20 Our research has also shown high Tβ4 presence in tumour infiltrating mast cells.21 Overall, our research suggests that Tβ4 has an important role in the development of different embryonic and adult organs. Due to controversy in the scientific community regarding the role of Tβ4 in health and disease, this study was aimed at verifying if similarities exist between Tβ4 presence dur- ing development and in adult life, and at dis- cussing the putative role played by Tβ4 in both situations. We also found it necessary to bet- ter investigate the presence of Tβ4 in the human urinary and reproductive tract of foe- tuses and adults in order to add new scientific data for a more complete description of the several, and not completely known, functions of this versatile peptide. Correspondence: Dr. Sonia Nemolato, Diparti- mento di Citomorfologia, Divisione di Anatomia Patologica, University of Cagliari, via Ospedale 54, 09124 Cagliari, Italy. Tel. +39.070.6092370 - Fax +39.070.657882. E-mail: sonianemolato@libero.it Key words: thymosin β4, genitourinary tract, development. Contributions: SN conceived and designed the experiments, acquisition of data, performed the experiments, analyzed the data, wrote the manu- script; TC designed the experiments, analyzed the data, wrote the manuscript; MF, FC designed and performed the experiments, contributed reagents/materials/analysis tools; DF, CG con- ceived and designed the experiments, acquisition of data, performed the experiments, analyzed the data, wrote the manuscript; BM, conceived and designed the experiments, analyzed the data, wrote the manuscript; IM conceived and designed the experiments, performed the experiments, analyzed the data, wrote the manuscript, critical revision of the manuscript and approval of the article; MC, GF conceived, designed and per- formed the experiments, analyzed the data, wrote the manuscript, critical revision of the manu- script and approval of the article. All authors read and approved the final manuscript. Acknowledgements: the authors thank Mr. Iganzio Ferru for his secretarial assistance, and Mrs. Sandra Serra and Mrs. Simonetta Paderi for their technical support. They also would like to acknowledge the financial support of the “Fon- dazione Banco di Sardegna”, Cagliari, Sardinia, Italy. Conflict of interest: the authors report no conflict. Received for publication: 16 July 2010. Accepted for publication: 20 September 2010 This work is licensed under a Creative Commons Attribution 3.0 License (by-nc 3.0). ©Copyright S. Nemolato et al., 2010 Licensee PAGEPress, Italy European Journal of Histochemistry 2010; 54:e43 doi:10.4081/ejh.2010.e43 Materials and Methods Four human foetuses, two males and two females, with gestational age ranging from 14 to 27 weeks, and four adults, two males and two females 35, 66, 68 and 72 year-old respec- tively, were selected for this study. In all cases, no pathological changes were evident in the organs examined in this study. We obtained tissue samples at autopsy from each subject including the following segments of the male and female genitourinary tract: kidney, blad- der, uterus, ovary, testicle and prostate. Tissue [European Journal of Histochemistry 2010; 54:e43] [page 201]