Toll-like receptor 2 mediates the immune response of the bovine oviductal ampulla to sperm binding

We previously reported that sperm binding to cultured bovine oviduct epithelial cells induces an anti-inflammatory immune response. Now we have developed a differentiated explant model to focus on the oviductal ampulla, where fertilization occurs, and to study the effect of sperm capacitation on the immune response. We used heparin to stimulate bovine sperm capacitation. Fluorescence imaging showed that 5,5MODIFIER LETTER PRIME,6,6MODIFIER LETTER PRIME-tetrachloro-1,1MODIFIER LETTER PRIME,3,3MODIFIER LETTER PRIME-tetraethylbenzimidazolyl-carbocyanine iodide-labeled sperm pretreated with (Hep((+))) or without (Hep(()(-))) heparin rapidly attached to the explant ciliated epithelium in similar numbers. However, only Hep((+))sperm upregulated explant messenger RNA (mRNA) transcription ofTLR2, IL8, TGFB1, andPGES, without changes inTNFAandIL-10expression, while Hep(()(-))sperm only upregulatedPGES. The responses were primarily anti-inflammatory, with a greater response produced by Hep((+))sperm, which also produced a substantial increase in TLR2 protein expression in the epithelium. The addition of TLR1/2 (toll-like receptor 1/2) antagonist to the Hep((+))and (Hep(()(-))) sperm-explant coincubations reduced sperm attachment to the epithelium and inhibited TLR2 protein expression and some of the Hep((+))sperm-induced mRNA transcription. Our observations suggest that the ampullar epithelium immunologically reacts more strongly to sperm that have undergone heparin stimulation of capacitation. This anti-inflammatory response could serve to protect capacitated sperm as they approach the oocyte in the ampulla.