American Journal of Reproductive Immunology

Xu JP, Li X, Mori E, Guo MW, Matsuda I, Takaichi H, Amano T, Mori T. Expression of Fas‐Fas ligand in murine testis. AJRI 1999; 42:381–388 © Munksgaard, Copenhagen

PROBLEM: During spermatogenesis, it has been suggested that the number of germ cells to be matured is regulated and restricted through the apoptotic mechanism. In the present study, we investigated the expression and apoptotic role of Fas and Fas ligand (L) in the murine testis.

METHOD OF STUDY: The expression of Fas‐FasL in the murine testis was assessed by reverse transcriptase‐polymerase chain reaction (RT‐PCR)‐Southern blot hybridization, in situ hybridization, and Western blot methods. The terminal deoxynucleotide transferase mediated dUTP‐nick end label (TUNEL) and DNA fragmentation methods were applied to detect the generation of apoptosis in germ cells.

RESULTS: By means of RT‐PCR‐Southern blot hybridization, we demonstrated the positive expression of Fas in testicular germ cells, and of FasL in testicular cells, supporting the findings with in situ hybridization that Fas was localized in germ cells, whereas FasL was localized in Sertoli cells of murine testis. A specific band at 45 kDa was obtained in the lysates from testis and germ cells with Western blot analysis. Then, the co‐incubation of germ cells with Spodoptera frugiperda (Sf9)‐FasL cells in vitro resulted in the induction of apoptosis in germ cells detected by the TUNEL method. Furthermore, DNA fragmented ladders were also demonstrated in germ cells co‐incubated with Sf9‐FasL cells.

CONCLUSION: Fas‐FasL system seemed to play an apoptotic role in spermatogenesis by the molecular interaction between FasL on Sertoli cells and Fas on germ cells.

PROBLEM: To determine the ontogeny of major histocompatibility complex (MHC) expression and TAP products in mouse embryos.

METHOD OF STUDY: mRNAs encoding MHC and associated molecules were identified by reverse transcriptase‐polymerase chain reaction, and the protein products were localized by confocal microscopy.

RESULTS: mRNAs encoding class Ia (H‐2D^b) and class Ib (Q7/9) were present in one‐cell embryos, whereas β₂‐microglobulin (β₂‐m) transcripts were not detected until the two‐cell stage. Transporter TAP1, but not TAP2, transcripts were detected only in blastocysts. H‐2 class Ia (classical) protein was detected on the surface of two‐cell embryos, H‐2 class Ib (nonclassical) protein was detected on one‐cell embryos, and β₂‐m transcripts were detected on eight‐cell embryos; TAP1 protein was present at low levels in the cytoplasm from the one‐cell stage onward, increasing in expression in blastocysts.

CONCLUSIONS: In mice, MHC class I mRNAs encoding the heavy chain of H‐2‐ and Q7/9‐encoding Qa2 molecules are synthesized soon after conception prior to implantation. Similarly, the nonpolymorphic MHC class I‐associated molecule β₂‐m also is expressed before implantation. TAP1, but not TAP2, is first detected at the blastocyst stage, thus preceding the onset of TAP2 in embryonic development.

PROBLEM: Previous studies have shown that the uterus and vagina contain cells that can present antigen to ovalbumin‐specific T‐cells. The objective of the present study was to systematically characterize the immune cells [major histocompatibility complex (MHC) class‐II+, macrophages, granulocytes, dendritic cells, and CD8+ cells] present in the uterus and vagina of the rat and to examine their distribution at various stages of the estrous cycle.

METHOD OF STUDY: Uterine and vaginal tissues from female rats were selected at various stages of the estrous cycle and were examined by immunohistochemical analysis. MHC class‐II (Ia)‐positive cells were detected using the OX‐6 monoclonal antibody; macrophages, granulocytes, and dendritic cells were detected by OX‐41 monoclonal antibody and CD8‐positive T‐cells were identified by OX‐8 monoclonal antibody.

RESULTS: Immunohistochemical analysis showed cycle‐dependent changes in the immune cell populations in the uterus and vagina. Ia+ cells, macrophages, granulocytes, and dendritic cells were present in large numbers in the stroma of the endometrium and around the glandular epithelium in the uterus at estrus, the stage of the reproductive cycle when estradiol levels are known to be high, relative to those seen at diestras, when estrogen levels are low and progesterone is the predominant hormone. CD8+ cells were observed in the uterus interspersed between glandular epithelial cells at estrus. Immune cells were more numerous in the vagina, relative to the uterus. OX‐6‐ and OX‐41‐positive cells were present in greater numbers in the subepithelial layers of the vagina at diestras, in contrast to estrus.

CONCLUSION: This study demonstrates that a variety of immune cells are present in the reproductive tract and that their number and distribution vary in a tissue‐specific manner with the stage of the estrous cycle.

Obesity and metabolic syndrome (MetS) are global epidemics, driven by an obesogenic environment. This is mediated by complex underlying pathophysiology, in which chronic inflammation is an important aetiological and mechanistic phenomenon. A shift towards a subclinical T_H1–lymphocyte mediated innate and chronic inflammatory response is well defined in obesity and MetS, demonstrated in multiple systems including visceral adiposity, brain (hypothalamus), muscles, vasculature, liver, pancreas, testes, epididymis, prostate and seminal fluid. Inflammatory cytokines disrupt the hypothalamic‐pituitary‐testes axis and steroidogenesis cascades (hypogonadotropic hypogonadism), spermatogenesis (poor semen parameters, including DNA fragmentation and detrimental epigenetic modification) and results in subclinical prostatitis and prostate hyperplasia. This review aims to highlight the role of chronic inflammation in obesity and MetS, cytokines in male reproductive physiology and pathophysiology, the impact on steroidogenesis and spermatogenesis, prostate pathology and erectile dysfunction. Currently, it is recommended that clinical assessment of male infertility and reproductive dysfunction in obese and MetS patients includes inflammation assessment (highly sensitive C‐reactive protein), and appropriate advice and therapeutic options are incorporated in the management options. However, the mechanisms and therapeutic options remain poorly understood and require significant interdisciplinary research to identify potential novel therapeutic strategies.

During pregnancy, the placenta is a site of active oxygen metabolism that continuously generates oxidative stress (OS). Overproduction of reactive oxygen species and reactive nitrogen species can destroy normal placental functions. Therefore, the feto‐placental unit generates abundant antioxidants to keep OS under control. Properly controlled oxidative species have been proven to serve as indispensable cellular signal messengers by regulating gene expression and downstream cellular activities. OS also plays an important immunoregulatory role during pregnancy. Oxidative disorder and immune disturbances are associated with adverse pregnancy outcomes such as spontaneous abortion, preeclampsia and intrauterine growth restriction. In this review, we introduce recent studies revealing basal functions and regulatory roles of placental OS in metabolism and immunity. The relationships between OS‐ and pregnancy‐related disorders are also discussed.