Seminal fluid factor increases the resistance of the tight functional complex of cultured human cervical epithelium CaSki cells

Abstract

Objective: To determine the effects of human seminal fluid on cervical paracellular resistance. Design: Experimental study. Setting: Healthy volunteers in an academic research environment; cultures of human CaSki cells on filters, with phenotypic characteristics of the endocervix. Patient(s): Healthy men donating sperm to a sperm bank. Intervention(s): Seminal fluid was obtained as the discarded fluid from ejaculates. Main Outcome Measure(s): Changes in transepithelial electrical resistance across CaSki cells on filters were determined in an Ussing chamber from successive measurements of the short-circuit current and the transepithelial potential difference. Changes in the dilution potential (and hence in the ratio of C1 − to Na + mobilities) were determined after lowering the NaCl concentration in the luminal solution. Result(s): Seminal fluid increased transepithelial electrical resistance acutely ( t 1 2 , 2 minutes), reversibly, and in a dose-related manner (ED 50, 1%). The effect of seminal fluid was abolished when the extracellular calcium level was lowered, and the increase in transepithelial electrical resistance correlated with a decrease in the ratio of Cl − to Na + mobilities, indicating an increase in the resistance of the tight junctional complex. The increase in transepithelial electrical resistance in response to seminal fluid was nonadditive to that of sn-1,2-dioctanoyl diglyceride (a stable diacylglyceride and activator of protein kinase C), and it was abolished by prolonged preincubation with the phorbol ester phorbol 12-myristate 13-acetate (to downregulate protein kinase C) or with staurosporin (to inhibit protein kinase C), suggesting that seminal fluid acts through a protein kinase C-dependent mechanism. Slower ( t 1 2 , 3.3 minutes) increases in transepithelial electrical resistance occurred when seminal fluid was added only to the luminal or the subluminal solution. Treatment with pertussis toxin, adenosine triphosphatase, or trypsin had no effect on the changes in transepithelial electrical resistance. Seminal fluid increased cytosolic calcium, but changes in cytosolic calcium are not important for the increases in transepithelial electrical resistance, suggesting that the effect of seminal fluid is not receptor-mediated. Preliminary studies indicate that the factor(s) in seminal fluid that increases transepithelial electrical resistance is a labile, low molecular weight (<10 kd) lipid. Conclusion(s): Seminal fluid may regulate cervical mucus production in vivo by modulating endocervical permeability.