GnRH在性成熟高白鲑神经系统及性腺中的分布定位

摘要：应用免疫组织化学方法,系统观察性成熟期高白鲑(Coregonus peled)神经系统及性腺中的促性腺激素释放激素( GnRH)的分布情况。结果表明,GnRH在大脑、小脑、中脑、脊髓、延髓中免疫阳性反应明显,且主要分布在神经元内。GnRH免疫阳性细胞在卵巢和精巢中均有分布,而且其阳性部位在卵巢主要分布于小生长期卵...     

Normal mouse intestinal epithelial cells as a model for the in vitro invasion of Trichinella spiralis infective larvae

It has been known for many years that Trichinella spiralis initiates infection by penetrating the columnar epithelium of the small intestine; however, the mechanisms used by the parasite in the establishment of its intramulticellular niche in the intestine are unknown. Although the previous observations indicated that invasion also occurs in vitro when the infective larvae are inoculated onto cultures of intestinal epithelial cells (e.g., human colonic carcinoma cell line Caco-2, HCT-8), a normal readily manipulated in vitro model has not been established because of difficulties in the culture of primary intestinal epithelial cells (IECs). In this study, we described a normal intestinal epithelial model in which T. spiralis infective larvae were shown to invade the monolayers of normal mouse IECs in vitro. The IECs derived from intestinal crypts of fetal mouse small intestine had the ability to proliferate continuously and express specific cytokeratins as well as intestinal functional cell markers. Furthermore, they were susceptible to invasion by T. spiralis. When inoculated onto the IEC monolayer, infective larvae penetrated cells and migrated through them, leaving trails of damaged cells heavily loaded with T. spiralis larval excretory-secretory (ES) antigens which were recognized by rabbit immune sera on immunofluorescence test. The normal intestinal epithelial model of invasion mimicking the natural environment in vivo will help us to further investigate the process as well as the mechanisms by which T. spiralis establishes its intestinal niche.     

Descent of the testis in the fetal calf. A summary of the anatomy and process

The descent of the testis in the fetal calf is reviewed, and the role in that process of the swelling reaction of the gubernaculum testis is discussed. The testes of 30 Dutch Friesian fetuses were examined by dissection and light microscopy of sections prepared from chemically and frozen-fixed specimens. The gubernaculum remains unattached to the scrotal fasciae until descent is completed. Shortening of the intra-abdominal gubernaculum and displacement of the testis begins at fetal week 11; the swelling reaction of the gubernaculum occurs between weeks 14 and 15. The testis is at the deep inguinal ring by week 15, and by week 20 it is in the scrotal position and the gubernaculum has regressed. It is proposed that the swelling of the gubernaculum dilates the vaginal ring and enlarges the inguinal canal. The clinical importance of these anatomical relationships and changes is discussed.     

Endothelial cell migration directs testis cord formation

While the molecular cues initiating testis determination have been identified in mammals, the cellular interactions involved in generating a functional testis with cord and interstitial compartments remain poorly understood. Previous studies have shown that testis cord formation relies on cell migration from the adjacent mesonephros, and have implicated immigrant peritubular myoid cells in this process. Here, we used recombinant organ culture experiments to show that immigrant cells are endothelial, not peritubular myoid or other interstitial cells. Inhibition of endothelial cell migration and vascular organisation using a blocking antibody to VE-cadherin, also disrupted the development of testis cords. Our data reveal that migration of endothelial cells is required for testis cord formation, consistent with increasing evidence of a broader role for endothelial cells in establishing tissue architecture during organogenesis.     

Establishment of intestinal epithelial cell lines from adult mouse small and large intestinal crypts

Small and large intestinal epithelial cell (IEC) lines were established from adult murine intestinal crypts. Both established small and large IECs line (named aMoS7 and aMoC1 respectively) expressed epithelial markers. Similarly to IECs isolated from adult mouse intestines, the expression of major histocompatibility complex (MHC) class II molecules was induced by interferon-γ-treatment in both established cell lines. This expression of MHC class II molecules was higher in small intestinal aMoS7 cells than in large intestinal aMoC1 cells. Treatment with lipopolysaccharide and with ligands of Toll-like receptors 1, 2, 3, and 7 induced secretion of interleukin-6 from both adult IEC lines. These results suggest that the aMoS7 and aMoC1 cell lines can serve as useful tools in analyzing the immunological functions of IECs, especially in studying the IEC response to microbial components and its antigen presenting ability.     

Annexin A2 Regulates β1 Integrin Internalization and Intestinal Epithelial Cell Migration

The gastrointestinal epithelium functions as an important barrier that separates luminal contents from the underlying tissue compartment and is vital in maintaining mucosal homeostasis. Mucosal wounds in inflammatory disorders compromise the critical epithelial barrier. In response to injury, intestinal epithelial cells (IECs) rapidly migrate to reseal wounds. We have previously observed that a membrane-associated, actin binding protein, annexin A2 (AnxA2), is up-regulated in migrating IECs and plays an important role in promoting wound closure. To identify the mechanisms by which AnxA2 promotes IEC movement and wound closure, we used a loss of function approach. AnxA2-specific shRNA was utilized to generate IECs with stable down-regulation of AnxA2. Loss of AnxA2 inhibited IEC migration while promoting enhanced cell-matrix adhesion. These functional effects were associated with increased levels of β1 integrin protein, which is reported to play an important role in mediating the cell-matrix adhesive properties of epithelial cells. Because cell migration requires dynamic turnover of integrin-based adhesions, we tested whether AnxA2 modulates internalization of cell surface β1 integrin required for forward cell movement. Indeed, pulse-chase biotinylation experiments in IECs lacking AnxA2 demonstrated a significant increase in cell surface β1 integrin that was accompanied by decreased β1 integrin internalization and degradation. These findings support an important role of AnxA2 in controlling dynamics of β1 integrin at the cell surface that in turn is required for the active turnover of cell-matrix associations, cell migration, and wound closure.     

Macrophage migration inhibitory factor-induced Ca(2+) response in rat testicular peritubular cells

Macrophage migration inhibitory factor (MIF), originally described as a T-cell product, has recently been identified in several endocrine organs. In the rat testis, MIF is secreted by the Leydig cells into testicular interstitial fluid that directly contacts Sertoli and peritubular cells. To investigate whether MIF is involved in calcium-dependent signal transduction, we have isolated rat Sertoli and peritubular cells. Despite progress in understanding functional properties of MIF, the molecular mechanism of MIF action in target cells is almost completely unknown. Here we find that recombinant MIF evokes a transient increase in calcium levels in peritubular cells but not in Sertoli cells from dissociated rat testis. Concentrations in the range between 12.5 ng/ml and 120 ng/ml of recombinant MIF were found to be effective, with 50 ng/ml yielding the largest increase in intracellular calcium. Preincubation of MIF with a neutralizing monoclonal antibody specifically blocked the response. Incubation of the peritubular cells in calcium-free buffer clearly decreased the evoked response in intracellular calcium concentration. However, the calcium response was greatly decreased by thapsigargin, an inhibitor of the Ca(2+) ATPase of the endoplasmic reticulum. The results strongly indicate that calcium is mobilized from reticulum stores during MIF-mediated signal transduction in the testis. In conclusion, our results provide the first characterization of MIF signal transduction in the testis and suggest that signaling from Leydig cells to peritubular cells through MIF is mediated by receptors coupled to release of intracellular calcium.     

Modulation of the expression of histocompatibility antigens class I (HLA-A,B,C) in the human pancreas

In this study the expression of HLA class I molecules was analysed on caudal portions of ten pancreata from cadaver donors by means of indirect immunoperoxidase and immunophosphatase techniques. In 7 out of ten pancreata the results showed that islets tissue was almost negative for the expression of HLA Class I antigens as opposed to exocrine tissue that appeared positive. Within exocrine tissue and large sized islets strongly positive interstitial cells were also detected. Double stainings showed that the strongly positive interstitial cells expressed also Leu M1 antigens. Preliminary studies on the remaining three pancreata demonstrate an increase of hematic interstitial cells together with a parallel increase of HLA class I antigens by endocrine parenchyma. The above data suggest that an increase of interstitial cells within pancreas may influence islets antigenicity.     

The role of autophagy in maintaining intestinal mucosal barrier

The intestinal mucosal barrier is the first line to defense against luminal content penetration and performs numerous biological functions. The intestinal epithelium contains a huge surface that is lined by a monolayer of intestinal epithelial cells (IECs). IECs are dominant mediators in maintaining intestinal homeostasis that drive diverse functions including nutrient absorption, physical segregation, secretion of antibacterial peptides, and modulation of immune responses. Autophagy is a cellular self-protection mechanism in response to various stresses, and accumulating studies have revealed its importance in participating physiological processes of IECs. The regulatory effects of autophagy depend on the specific IEC types. This review aims to elucidate the myriad roles of autophagy in regulating the functions of different IECs (stem cells, enterocytes, goblet cells, and Paneth cells), and present the progress of autophagy-targeting therapy in intestinal diseases. Understanding the involved mechanisms can provide new preventive and therapeutic strategies for gastrointestinal dysfunction and diseases.     

Differential expression of tumor-associated genes and altered gut microbiome with decreased Akkermansia muciniphila confer a tumor-preventive microenvironment in intestinal epithelial Pten-deficient mice

Phosphatase and tensin homolog (Pten) antagonizes PI3K-Akt signaling; therefore, Pten impairment causes tumorigenesis. However, the correlation between Pten deficiency and colon cancer has remained elusive due to numerous opposite observations. To study this correlation, we examined whether Pten deficiency in intestinal epithelial cells (IECs) induces tumorigenesis.With mucosal biopsies of human colon cancer and normal colon, Pten mRNA was evaluated by quantitative PCR. Using IEC-specific Pten knockout mice (Pten^ΔIEC/ΔIEC), we examined the mitotic activity of IECs; and Pten^ΔIEC/ΔIEC; Apc^min/+ mice were generated by combining Pten^ΔIEC/ΔIEC with Apc^min/+ mice. Tumor-associated gene was evaluated by micro-array analysis. Fecal microbiome was analyzed through 16S rRNA gene sequencing.We found that Pten mRNA level was reduced in human colon cancer relative to normal tissues. Augmented chromatids, increased Ki-67 and PCNA expression, and enhanced Akt activation were identified in IECs of Pten^ΔIEC/ΔIEC mice compared to Pten^+/+ littermate. Combining Pten^ΔIEC/ΔIEC with Apc^min/+ condition caused rapid and aggressive intestinal tumorigenesis. However, Pten^ΔIEC/ΔIEC mice did not develop any tumors. While maintaining the tumor-driving potential, these data indicated that IEC-Pten deficiency alone did not induce tumorigenesis in mice. Furthermore, the expression of tumor-promoting and tumor-suppressing genes was decreased and increased, respectively, in the intestine of Pten^ΔIEC/ΔIEC mice compared to controls. The abundance of Akkermansia muciniphila, capable of inducing chronic intestinal inflammation, was diminished in Pten^ΔIEC/ΔIEC mice compared to controls.These findings suggested that altered tumor-associated gene expression and changed gut microbiota shape a tumor-preventive microenvironment to counteract the tumor-driving potential, leading to the tumor prevention in Pten^ΔIEC/ΔIEC mice.     

Apc+/Min colonic epithelial cells express TNF receptors and ICAM-1 when they are co-cultured with large intestine intra-epithelial lymphocytes

Adenomatous polyposis coli (APC) functions are involved in the heterotypic interactions occurring between intestinal epithelial cells (IECs) and intra-epithelial lymphocytes (IELs). These interactions may be of interest in cancer prevention, since recent data provide evidence for lymphocyte mediated immunosurveillance of epithelial cancers. The present study attempts to determine if APC inactivation induces changes in the cross-talk between IEC and large intestine IEL (LI-IEL) through intercellular adhesion molecule (ICAM-1)/leukocyte function-associated (LFA-1) interactions. Mouse Apc+/+ and Apc+/Min colonocytes were co-cultivated with LI-IEL. When co-cultured with LI-IEL Apc+/Min IEC but not Apc+/+ IEC expressed high levels of ICAM-1. The presence of ICAM-1 was linked to TNFalpha production in both co-cultures and TNFR expression only in co-cultivated Apc+/Min IEC. Finally, butyrate enhanced the expression of ICAM-1 in Apc+/Min IEC co-cultured with LI-IEL, and the secretion of TNFalpha by both types of co-cultures. These events could participate in determining the Apc+/Min IEC immunogenicity under different in vivo conditions.     

Ultrastructural and immunohistochemical studies on steroid-secreting cells of the testis and ovary of normal and 3-methylcholanthrene-treated mice

Summary The testis and ovary of normal and 3-methylcholanthrene-treated mice were studied ultrastructurally and immunohistochemically in order to learn whether steroid-secreting cells of the gonads are involved in drug metabolism. The steroid-secreting cells, i.e., Leydig cells of the testis, and theca interna cells, interstitial gland cells, and corpus luteum cells of the ovary of 3-methylcholanthrene-treated mice, show a strong positive reaction to the antiserum against, hepatic microsomal cytochrome P-450, of liver which is the terminal oxidase of the drug-metabolizing enzyme complex. In addition, it was found that elements of smooth endoplasmic reticulum (SER) in drug-treated mice become well developed as compared with those in control animals. These findings indicate that the steroid secreting cells in testis as well as ovary are involved in the metabolism of both endogenous and exogenous chemical compounds.This study was supported by grants from the Ministry of Education, Science and Culture, Japan     

Enteroendocrine cells express functional Toll-like receptors

Intestinal epithelial cells (IECs) provide a physical and immunological barrier against enteric microbial flora. Toll-like receptors (TLRs), through interactions with conserved microbial patterns, activate inflammatory gene expression in cells of the innate immune system. Previous studies of the expression and function of TLRs in IECs have reported varying results. Therefore, TLR expression was characterized in human and murine intestinal sections, and TLR function was tested in an IEC line. TLR1, TLR2, and TLR4 are coexpressed on a subpopulation of human and murine IECs that reside predominantly in the intestinal crypt and belong to the enteroendocrine lineage. An enteroendocrine cell (EEC) line demonstrated a similar expression pattern of TLRs as primary cells. The murine EEC line STC-1 was activated with specific TLR ligands: LPS or synthetic bacterial lipoprotein. In STC-1 cells stimulated with bacterial ligands, NF-kappaB and MAPK activation was demonstrated. Furthermore, the expression of TNF and macrophage inhibitory protein-2 were induced. Additionally, bacterial ligands induced the expression of the anti-inflammatory gene transforming growth factor-beta. LPS triggered a calcium flux in STC-1 cells, resulting in a rapid increase in CCK secretion. Finally, conditioned media from STC-1 cells inhibited the production of nitric oxide and IL-12 p40 by activated macrophages. In conclusion, human and murine IECs that express TLRs belong to the enteroendocrine lineage. Using a murine EEC model, a broad range of functional effects of TLR activation was demonstrated. This study suggests a potential role for EECs in innate immune responses.     

Lipid rafts mediate internalization of beta1-integrin in migrating intestinal epithelial cells

Intestinal mucosal inflammation is associated with epithelial wounds that rapidly reseal by migration of intestinal epithelial cells (IECs). Cell migration involves cycles of cell-matrix adhesion/deadhesion that is mediated by dynamic turnover (assembly and disassembly) of integrin-based focal adhesions. Integrin endocytosis appears to be critical for deadhesion of motile cells. However, mechanisms of integrin internalization during remodeling of focal adhesions of migrating IECs are not understood. This study was designed to define the endocytic pathway that mediates internalization of beta(1)-integrin in migrating model IECs. We observed that, in SK-CO15 and T84 colonic epithelial cells, beta(1)-integrin is internalized in a dynamin-dependent manner. Pharmacological inhibition of clathrin-mediated endocytosis or macropinocytosis and small-interfering RNA (siRNA)-mediated knock down of clathrin did not prevent beta(1)-integrin internalization. However, beta(1)-integrin internalization was inhibited following cholesterol extraction and after overexpression of lipid raft protein, caveolin-1. Furthermore, internalized beta(1)-integrin colocalized with the lipid rafts marker cholera toxin, and siRNA-mediated knockdown of caveolin-1 and flotillin-1/2 increased beta(1)-integrin endocytosis. Our data suggest that, in migrating IEC, beta(1)-integrin is internalized via a dynamin-dependent lipid raft-mediated pathway. Such endocytosis is likely to be important for disassembly of integrin-based cell-matrix adhesions and therefore in regulating IEC migration and wound closure.     

Building a testis: formation of functional testis tissue after transplantation of isolated porcine (Sus scrofa) testis cells

During mammalian development, morphogenesis of the testis requires the coordinated interplay of somatic cells to form seminiferous cords in which the primitive germ cells reside. These cords are the precursor of the functional male gonad and as such form the basis of male fertility. Cell migration during mammalian organogenesis and formation of complex tissues, such as the testis, are difficult to study in situ. Herein, we report extensive rearrangement of cells to regenerate complete functional testis tissue after implantation of isolated neonatal porcine testis cells under the skin of immunodeficient mice. Somatic cells and germ cells reorganized into structures that have remarkable morphologic and physiologic similarity to normal testis tissue, forming the endocrine and spermatogenic compartment of the testis. This unique in vivo system provides an accessible model for the study of testicular morphogenesis that could be especially useful in nonrodent species.     

Autocrine IL-15 mediates intestinal epithelial cell death via the activation of neighboring intraepithelial NK cells

Intestinal intraepithelial lymphocytes (IELs), which reside between the basolateral faces of intestinal epithelial cells (IECs), provide a first-line defense against pathogens via their cytotoxic activity. Although IEC-derived IL-7 and IL-15 are key regulatory cytokines for the development and activation of IELs, we report here that IL-15 but not IL-7 mediates the reciprocal interaction between IELs and IECs, an important interaction for the regulation of appropriate mucosal immunohomeostasis. IL-15-treated IELs induced cell death in IECs via the cytotoxic activity in vitro. Among the different subsets of IL-15-treated IELs, CD4(-)CD8(-)TCR(-) IELs, which express NK marker (DX5 or NK1.1), showed the most potent syngenic IEC killing activity. These intraepithelial NK cells expressed Ly-49 molecules, NKG2 receptors, and perforin. These results suggest the possibility that the cell death program of IECs could be regulated by self-produced IL-15 through the activation of intraepithelial NK cells.     

Sertoli-germ cells interactions in the human testis.

In previous histoimmunochemical studies we reported that transferrin (TF) and insulin-like growth factor I (IGF-I) are present in the cytoplasm of the Sertoli cells of the adult human testis. Receptors for TF were found mainly in adluminal germ cells and type I receptors for IGF-I both in Sertoli and germ cells. Using electron microscopy, evidence of transfer of both TF and IGF-I from the Sertoli to the germ cells through a receptor-mediated endocytosis mechanism was also found. In this paper we report the results of the histoimmunochemical localization of alpha inhibin in the human fetal, prepubertal and adult testis. In 8- to 14-week-old fetal testes a positive immunostaining was found mainly in the interstitial cells, whereas no staining was found in the germ cords. In the prepubertal testis the immunostaining was present in the Sertoli cells but not in the interstitial cells. In the adult human testis the immunostaining was present not only in the Sertoli cells but also in the spermatocytes and in several Leydig cells. Using electron microscopy and immunogold labeling the presence of alpha inhibin immunoreactivity was found in the rough endoplasmic reticulum and in the Golgi cisternae of both Sertoli and Leydig cells. Moreover we found evidence of transfer of alpha inhibin from the Sertoli to the germ cells through receptor-mediated endocytosis.