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This Article Full Text Full Text (PDF) [Supplemental Figure] All Versions of this Article: 79/6/1135    most recent biolreprod.108.069930v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal My Folders Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rodrigues, A. Articles by Avellar, M. C. W. Search for Related Content PubMed PubMed Citation Articles by Rodrigues, A. Articles by Avellar, M. C. W. Agricola Articles by Rodrigues, A. Articles by Avellar, M. C. W.

Activation of Toll-Like Receptor 4 (TLR4) by In Vivo and In Vitro Exposure of Rat Epididymis to Lipopolysaccharide from Escherichia Coli¹

Section of Experimental Endocrinology,³ Department of Pharmacology, Universidade Federal de São Paulo, Escola Paulista de Medicina, São Paulo, São Paulo 04044-020, Brazil Department of Pediatrics,⁴ University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7500

ABSTRACT

This study provides the first evidence that rat epididymis is fully capable of initiating an inflammatory response to lipopolysaccharide (LPS) from Escherichia coli through activation of Toll-like receptor 4 (TLR4). TLR4 functionality was demonstrated by in vivo LPS challenge, which induced a time- and dose-dependent activation of the transcription factor nuclear factor kappa B (NFKB) in caput and cauda epididymides. NFKB activation by LPS in caput epididymidis was abrogated when rats were pretreated with the NFKB inhibitor PDTC, confirming the specificity of this response. Within 2 h of LPS treatment (0.01 and 1 mg/kg, i.v.), NFKB activation in caput and cauda was accompanied by upregulation of Il1b, Nfkbia, and Cd14, but not Tlr4, mRNA. These effects, however, were not sustained after 24 h of LPS treatment. Lipopolysaccharide systemic effects were not restricted to epididymides, since Il1b, Nfkbia, and Cd14 mRNAs were also upregulated in other male reproductive tissues from LPS-treated rats (1 mg/kg, i.v., 2 h). Constitutive TLR4 was immunolocalized in some, but not all, epididymal epithelial cells and in interstitial cells, some of them identified as resident ED2-positive macrophages. No change in TLR4 immunostaining pattern was observed when epididymides from control and LPS-treated rats were compared (1 mg/kg, i.v., 2 h and 24 h). Significant NFKB activation was also achieved within 1 min of in vitro incubation of caput epididymidis with LPS (0.01–5 µg/ml), confirming that components for TLR4 signaling cascade activation are fully active in this tissue. This study contributes to a better understanding of the innate immune response in the epididymis and other tissues from the male reproductive tract.

epididymis, gene regulation, lipopolysaccharide, rodent, transcription factor

¹Supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) grant 05/55738-8 and Coordenação Nacional à Pesquisa (CNPq) grant 475238/2006-0. M.C.W.A. is a research fellow from CNPq; A.R., E.J.R.S., and D.B.C.Q. were supported by CAPES; L.H. was supported by the Fogarty International Center Program for Training and Research in Population and Health D43TW/HD00627 (subcontract UNIFESP/UNC 5-53284).

Correspondence: ²Maria Christina W. Avellar, Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo, Escola Paulista de Medicina, Rua 03 de maio 100, INFAR, Vila Clementino, São Paulo, SP 04044-020, Brazil. FAX: 55 11 5576 4448; e-mail: avellar{at}farm.epm.br