Approximately 30 mL of midstream urine was collected from each cow into a sterile 50 mL conical tube after stimulation of the perineal area. of transmission in any animal is the colonization of the renal tubule and excretion by urine; however, can also colonize the female reproductive tract of cows and can Pimecrolimus be transmitted by semen. Vaccination Pimecrolimus against in the US is routine in cattle, but immunity is IGLC1 not guaranteed. The cell wall of contains toll-like receptor agonists including peptidoglycan and lipopolysaccharide. The capacity of to initiate an innate inflammatory response from uterine endometrial cells is unknown but may be a cause of reproductive failure. Using cell culture, we tested the capacity of bovine endometrial epithelial cells or human monocytes to elicit an inflammatory response to serovar Hardjo strain TC273. Cells were exposed to either heat-killed outer membrane, lipopolysaccharide, Pam3CSK4 or medium alone for 2 to 24 h. Exposure of bovine endometrial epithelial cells or human monocytes to heat-killed or outer membrane did not induce the expression of or lipopolysaccharide or Pam3CSK4 increased the expression of and compared to control cells. This data suggest that does not trigger a classical inflammatory response in endometrial cells. Understanding the interaction between and the female reproductive tract is important in determining the mechanisms of Leptospirosis associated with reproductive failure. Lay summary Cows infected with the have abortion and stillbirth. It is not known how causes pregnancy failure in the cow. We tested if causes inflammation in cells of the uterus which triggers pregnancy failure. We collected cells from the uterus of healthy cows at the abattoir and placed them into culture with and measured the expression of genes associated with inflammation. To our surprise, cells of the uterus did not respond to which may go on to cause reproductive failure in cows. Understanding how interact with cells of the uterus will help reduce pregnancy failure of cows with leptospirosis. 2015, Torgerson 2015). Numerous mammalian species serve as hosts for including rodents and cattle (Nally 2016). infection occurs after exposure to environments contaminated by spirochetes, and the subsequent colonization of the renal tubule that results in intermittent excretion of spirochetes in the urine and further contamination of the environment. Infected hosts may be asymptomatic or present a variety of clinical symptoms including fever, liver failure, respiratory distress, and reproductive failure (Ellis 2015). In cattle, the greatest impact of leptospirosis is abortion, stillbirth, premature birth, reproductive failure, and milk drop syndrome (Ellis 2015, Loureiro & Lilenbaum 2020). Cattle are susceptible to infection with multiple species and serovars including serovar Hardjo, serovar Pomona, serovar Grippotyphosa, and (Miller 1991, Martins 2015, Nally 2018). The most prominent species of associated with reproductive failure in cattle is serovar Hardjo which decreases conception rate and increases calving to conception interval (Ellis Pimecrolimus 1981, Miller 1991, Guitian 1999, Rajeev 2014). Vaccination of cattle to serovars Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona is common in the US and is an effective measure to prevent losses due to abortion and milk production. However, vaccination does not prevent infection and renal colonization, which results in vaccinated animals becoming carriers of (Hanson et al. 1972, Srivastava 2006). In addition, host responses vary following vaccination suggesting a Pimecrolimus lack of complete and long-lasting protection, especially to serovar Hardjo (Bolin et al. 1989, 1991, Rodrigues et al. 2011). A large proportion of the United States cattle herd is seropositive for pathogenic (up to 49%), while seronegative cows can still excrete spirochete to transmit the infection to other animals (Miller 1991, Talpada et al. 2003, Nally 2018). In cattle, leptospires have been isolated from the oviduct, uterus, aborted fetuses, and follicular fluid (Bielanski & Surujballi 1998, Bielanski 1998, Monte 2015, Loureiro & Lilenbaum 2020). Leptospires can migrate to the upper reproductive tract when administered intranasally or intracervically Pimecrolimus (Bielanski & Surujballi 1998, Bielanski 1998). Interestingly, the detection of in vaginal mucus by PCR is poorly correlated with detection in urine (Loureiro 2017, Pinna 2018). While leptospirosis causes reproductive failure in cattle, the mechanism by which this occurs is.