Sertoli Cells Induce Xenolymphocyte Apoptosis In Vitro

Therapeutic application of Sertoli cells for treatment of various diseases

Sertoli cells (SCs) are immune privileged cells found in the testis that function to immunologically protect maturing germ cells from immune destruction. This immune protection is due to the blood-testis-barrier, which prevents infiltration of cytotoxic immune cells and antibodies, and SC production of immunomodulatory factors, that favor a tolerogenic environment. The ability of SCs to create an immune privileged environment has led to the exploration of their potential use in the treatment of various diseases. SCs have been utilized to create a tolerogenic ectopic microenvironment, to protect co-grafted cells, and to deliver therapeutic proteins through gene therapy. To date, numerous studies have reported the potential use of SCs for the treatment of diabetes, neurodegenerative disorders, and restoration of spermatogenesis. Additionally, SCs have been investigated as a delivery vehicle for therapeutic products to treat other diseases like Laron syndrome, muscular dystrophy, and infections. This review will provide an overview of these therapeutic applications.

Fluoride reduced the immune privileged function of mouse Sertoli cells via the regulation of Fas/FasL system

Previous investigations have demonstrated the adverse impacts of fluoride on Sertoli cells (SCs), such as oxidative stress and apoptosis. SCs are the crucial cellular components that can create the immune privileged environment in testis. However, the effect of fluoride on SCs immune privilege is unknown. In this study, mouse SCs were exposed to sodium fluoride with varying concentrations of 10^-5, 10^-4, and 10^-3 mol/L to establish the model of fluoride-treated SCs (F-SCs) in vitro. After 48 h of incubation, F-SCs were transplanted underneath the kidney capsule of mice for 21 days, or cocultured with spleen lymphocytes for another 48 h. Immunohistochemical analysis of GATA4 in SCs grafts underneath kidney capsule presented less SCs distribution and obvious immune cell infiltration in F-SCs groups. In addition, the levels of FasL protein and mRNA in non-cocultured F-SCs decreased with the increase of fluoride concentration. When cocultured with F-SCs, lymphocytes presented significantly high cell viability and low apoptosis in F-SCs groups. Protein and mRNA expressions of FasL in cocultured F-SCs and Fas in lymphocytes were reduced, and the caspase 8 and caspase 3 mRNA levels were also decreased in fluoride groups in a dose-dependent manner. These findings indicated that fluoride influenced the testicular immune privilege through disturbing the Fas/FasL system.

Murine Sertoli cells promote the development of tolerogenic dendritic cells: a pivotal role of galectin-1

Sertoli cells (SCs) possess inherent immunosuppressive properties and are major contributors to the immunoprivileged status of mammalian testis. SCs have been reported to inhibit the activation of B cells, T cells and natural killer cells but not dendritic cells (DCs). Herein, we present evidence that co-culture with SCs results in a persistent state of DC immaturity characterized by down-regulation of the surface molecules I-A/E, CD80, CD83, CD86, CCR7 and CD11c, as well as reduced production of pro-inflammatory cytokines. SC-conditioned DCs (SC-DCs) displayed low immunogenicity and enhanced immunoregulatory functions, including the inhibition of T-cell proliferation and the promotion of Foxp3(+) regulatory T-cell development. Mechanistically, the activation of p38, extracellular signal-regulated kinase 1/2, and signal transducer and activator of transcription 3 was suppressed in SC-DCs. More importantly, we demonstrate that galectin-1 secreted by SCs plays a pivotal role in the differentiation of functionally tolerogenic SC-DCs. These findings further support the role of SCs in maintaining the immunoprivileged environment of the testis and provide a novel approach to derive tolerogenic DCs, which may lead to alternative therapeutic strategies for the treatment of immunopathogenic diseases.

Decreasing loss of cryopreserved-thawed rat islets by coculture with Sertoli cells

OBJECTIVE

Cryopreserved-thawed rat islets were cocultured with Sertoli cells to examine whether they could decrease the loss and improve islet function.

METHODS

Islets and Sertoli cells were harvested from the pancreas and the testis of Sprague-Dawley rats, respectively. Cryopreserved, stored islets were thawed and divided into groups of coculture with Sertoli cells versus single cells. We measured islets recovery rate and function. Apoptotic-related proteins and gene expressions were detected by Western blot and reverse-transcriptase polymerase chain reaction. Soluble factors secreted by Sertoli cells in to the supernate were detected by enzyme-linked immunosorbent assay. We compared islet graft survival times in diabetic mice.

RESULTS

In contrast to the single culture controls, thawed islets cocultured with Sertoli cells exhibited improved morphology. Recovery rates and insulin secretion were significantly higher among coculture cells. Four soluble factors were detected in supernates from Sertoli cell cultures including transforming growth factor-β, insulin-like growth factor-1, epidermal growth factor, and basic fibroblast growth factor. Expression of proapoptotic Bax and caspase 3, 7 were down-regulated while that of antiapoptotic Bcl-2 was up-regulated. Cotransplantation with Sertoli cells significantly prolonged islet graft survival.

CONCLUSION

These results suggested that coculture with Sertoli cells significantly improved islet yields and function after thawing and depressed islet apoptosis.

Immunology of the Testis and Male Reproductive Tract

A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.

Immunoprivileged sites: the testis

The testis is an immunological privileged tissue as evidenced by its ability to support grafts with minimal rejection. Immune privilege is essential for the tolerance of neo-antigens from developing germ cells that appear after the constitution of self-tolerance, but imposes the paradoxical task of also providing efficient protection against pathogens and tumor cells. It is becoming increasingly clear that immune privilege cannot be attributed to a single factor such as the sequestration of neo-antigens from the immune system behind the blood-testis barrier, but is based on a complex multifaceted interplay between cells and factors that are essential for the reproductive function of the testis and the testicular immune system. This review summarizes the evidence that has accumulated regarding the role of Sertoli cells, androgens, and selected population of leukocytes in the maintenance of immune privilege and its perturbation in testicular inflammatory sub- and infertility.

Cotransplantation with xenogenetic neonatal porcine sertoli cells significantly prolongs islet allograft survival in nonimmunosuppressive rats. Transplantation. 2009;88:339-345. [PMID: 19667935 DOI: 10.1097/tp.0b013e3181ae5dcf]

BACKGROUND

In addition to possessing immune privileged properties, Sertoli cells are known to actively suppress responses to cotransplanted cells. An important question is whether this "bystander suppression" is limited to cells of the same origin as the Sertoli cells or whether suppression extends to unrelated cells.

METHODS

Neonatal porcine Sertoli cells (NPSCs) were transplanted with allogeneic islets (Sprague-Dawley rat) into immune competent Wistar rats subsequent to induction of diabetes by alloxan administration.

RESULTS

Although allogeneic islets alone had a mean survival time of 5.67+/-0.94 days, islets cotransplanted with 1.5 x 10 xenogeneic NPSCs displayed a survival of 8.33+/-0.58 days. Increasing the concentration of NPSCs to 1.0 x10 yielded a further increase in survival to 16.33+/-1.53 days. Augmented islet survival was associated with reduced lymphocytic infiltrate and elevated numbers of Sox9 positive cells. Mechanistically, it seemed that Fas ligand was not involved in prolongation of survival because in contrast to adult Sertoli cells, NPSCs lacked expression of this gene.

CONCLUSIONS

These data suggest that xenogeneic Sertoli cells exert a global immune suppressive effect that extends across species barriers in a stringent model of alloimmune rejection. The combination of NPSCs with other immune modulatory regimes may yield novel approaches toward prevention of allo-islet transplant rejection.