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TLRs play a crucial role in early host defense against invading pathogens. In the seminiferous epithelium, Sertoli cells are the somatic nurse cells that mechanically segregate germ cell autoantigens by means of the blood-tubular barrier and create a microenvironment that protects germ cells from both interstitial and ascending invading pathogens. The objective of this study was to examine TLR expression and their functional responses to specific agonists in mouse Sertoli cells. We measured the expression of TLR2, TLR4, TLR5, and TLR6 mRNAs and confirmed by FACS analysis the presence of proteins TLR2 and TLR5 on which we focused our study. Stimulation of Sertoli cells with macrophage-activating lipopeptide-2, agonist of TLR2/TLR6, and with flagellin, agonist of TLR5, induces augmented secretion of the chemokine MCP-1. To assess the functional significance of MCP-1 production following TLR stimulation, conditioned medium from either macrophage-activating lipopeptide-2 or flagellin-treated Sertoli cells was tested for in vitro chemotaxis assay, and a significant increase of macrophage migration was observed in comparison with unstimulated conditioned medium. Moreover, we studied the role of NF-κB and of MAPKs in regulating TLR-mediated MCP-1 secretion by using inhibitors specific for each transduction pathway and we demonstrated a pivotal role of the IκB/NF-κB and JNK systems. In addition, TLR2/TLR6 and TLR5 stimulation induces increased ICAM-1 expression in Sertoli cells. Collectively, this study demonstrates the novel ability of Sertoli cells to potentially respond to a wide variety of bacteria through TLR stimulation.

Presenilin 1 (PS1) is a key factor for L L-amyloid (Ab) formation in Alzheimer disease (AD). Homocysteine accumulation, frequently observed in AD patients, may be a sign of a metabolic alteration in the S-adenosylmethionine (SAM) cycle, which generates the overexpression of genes controlled by methylation of their promoters, when the cytosine in CpG moieties becomes unmethylated. The methylation of a gene involved in the processing of amyloid precursor protein may prevent Ab formation by silencing the gene. Here we report that SAM administration, in human neuroblastoma SK-N-SH cell cultures, downregulates PS1 gene expression and Ab production. ß