Exploring Human Testicular Peritubular Cells: Identification of Secretory Products and Regulation by Tumor Necrosis Factor-α

Abstract

Testicular peritubular cells are myofibroblastic cells, which represent the major cellular components of the wall of the seminiferous tubules. In men their phenotypic characteristics, including possible secretory activity and regulation, are not well known, in neither normal nor pathologically altered testes. Especially in testes of men with impaired spermatogenesis, the cytoarchitecture of the tubular wall is frequently remodeled and presents fibrotic thickening, increased innervation, and infiltration by macrophages and mast cells. The latter are two sources of TNF-alpha. The purpose of our study was to explore human testicular peritubular cells and mechanisms of their regulation. To this end we primarily studied cultured human testicular peritubular cells (HTPCs), isolated from adult human testes. Having established that HTPCs express TNF-alpha receptors 1 and 2 and respond to recombinant human TNF-alpha by a rapid phosphorylation of ERK1/2, we used complementary approaches, including gene array/RT-PCR studies, Western blotting/immunocytochemistry, and ELISA techniques to study phenotypic characteristics of HTPCs and actions of TNFalpha. We found that HTPCs express the nerve growth factor gene and TNF-alpha-stimulated mRNA levels and secretion of nerve growth factor in a dose- and time-dependent manner. Similarly, monocyte chemoattractant protein-1 was identified as a product of HTPCs, which was regulated by TNF-alpha in a concentration- and time-dependent manner. TNF-alpha furthermore strongly enhanced expression and/or synthesis of other inflammatory molecules, namely IL-6 and cyclooxygenase-2. Active cyclooxygenase-2 is indicated by increased prostaglandin D2 levels. In addition, intercellular adhesion molecule-1, which was not detected at protein level in the absence of TNF-alpha, was induced upon TNF-alpha stimulation. In conclusion, these results provide novel insights into the nature of human peritubular cells, which are able to secrete potent signaling molecules and are regulated by TNF-alpha. These results also hint to an as-yet-unknown role of peritubular cells in normal human testis and involvement in the pathomechanisms associated with impaired spermatogenesis in men.

Testis peritubular myoid cells increase their motility and express matrix‐metalloproteinase 9 (MMP‐9) after interaction with embryonal carcinoma cells

“…Our TNF-a and a-SMA immunostaining and ELISA experiments revealed that other cell types release this cytokine in normal testicular processes as previously described (Suominen et al, 2004;Schell et al, 2008), pointing that our PTCs cultures could contain residual contaminations with other cell populations from the interstitial areas of the testes (i.e. immune cells).…”

“…The effect of this cytokine on the regulation of human testicular PTC secretory activity and its involvement in impaired spermatogenesis has been reported (Schell et al, 2008). Additionally, this factor has been found to play a role in tumor stroma cross talk, causing the upregulation of MMP-9 (Stuelten et al, 2005).…”

Association between periodontal status and idiopathic male infertility

“…Similar inflammatory molecules are important in regulating the blood-testis barrier, which affects the function of Sertoli cells. Tumor necrosis factor-alpha, transforming growth factor-β3 (40), and interleukin-1 can disturb blood-testis barrier dynamics (41). Interleukin-6 alters blood-testis barrier function by inhibiting protein degradation (42).…”

Human testicular peritubular cells: more than meets the eye

“…In an attempt to do so, our laboratory established a method to culture and study HTPCs. It is based on very small testicular tissue samples from adult patients with obstructive azoospermia but normal spermatogenesis (HTPCs) and non-obstructive azoospermia, impaired spermatogenesis, and testicular fibrosis (HTPCFs) (Albrecht et al 2006, Schell et al 2008, Spinnler et al 2010, Adam et al 2011.…”

“…They produce signaling factors, including interleukin 6 (IL6), monocyte chemotactic protein 1 (MCP1), nerve growth factor (NGF), and its precursor proNGF, as well as glial cell line-derived neurotropic factor (GDNF). Cyclooxygenase-2 (COX2) was detected upon TNFa treatment and prostaglandins, especially PGD2, and metabolites may also be among the produced factors (Schell et al 2008, Spinnler et al 2010. The cells express several antioxidant proteins, namely catalase, parkinin/DJ-1, peroxiredoxin 1, superoxide dismutases (SOD) 1 and 2, glutathione-S-transferase, and heme oxygenase (HMOX1) (Kampfer et al 2012).…”