The Mechanism Of Cortisol On Innate Immunity Of The Postpartum Goat Endometrium Infected With E.coli

Endometritis of goat does is one of the common postpartum diseases,which caused problems such as repeated infertility and increased elimination rate,resulting in large economic losses for goat production enterprises.Escherichia coli is the main pathogen of postpartum endometritis in does.Cortisol is a type of glucocorticoid that has anti-inflammatory and immunosuppressive effects.In our laboratory,cortisol has been demonstrated in vitro to inhibit LPS-induced inflammatory response in cow endometrial epithelial cells by regulating MAPK and NF-?B signaling pathways.But this mechanism has not been validated in goats.In this research,does were used as experimental animals to investigate the effect of cortisol on the innate immune mechanism of goat endometrium induced by E.coli,which provide a reference for the prevention and treatment of postpartum uterine infections in goats.1.Effect of cortisol on physiological indexes and endometrial histopathology of postpartum does with E.coli-induced endometritisDoes(n=24)were assigned to four groups(n=6):control,E.coli,cortisol,and E.coli+cortisol groups.The method of cortisol treatment:does in the cortisol and E.coli+cortisol group were injected intravenously with 20 mL of a mixture of cortisol(1 mg/kg)and saline.The control group and the E.coli group were injected with the same dose of saline.The above operation was twice a day for six consecutive days.Among them,does in the E.coli group and cortisol+E.coli group were administered via intrauterine infusion 10 mL of E.coli O55(109 CFU/mL)on the third day,each with 5 mL of each uterine horn.The control group and the cortisol group were perfused with the same amount of saline.Rectal temperature(T),heart rate(HR),respiratory rate(RR),and hysteroscopy were performed before(0 h)and 6,12,24,48,and 72 h after vaccination.Peripheral blood,uterine secretions and endometrial samples were collected for examination of peripheral blood leukocyte count(WBC),percentage of polymorphonuclear leukocytes(%PMN)in uterine secretion and endometrial histopathological changes.The results are as follows:(1)Compared with the control group,the T,HR,RR,and WBC of does in the E.coli group increased at 6,12,and 24 h(p<0.05).The cortisol+ E.coli group were lower than those in the E.coli group at 12 h(p<0.05).(2)The endometrial surface showed obvious hemorrhage spots and edema in the E.coli group at 12 h.Purulent secretions were observed at 12,24,and 48 h.Compared with the E.coli group,there was a smaller number of hemorrhage spots and milder edema in does treated with cortisol and E.coli at 12 h.The endometrial surface was similar to the control group at 72 h.(3)Compared with the control group,E.coli group showed a large mixture of inflammatory cells,red blood cells,and exfoliated epithelial cells in the secretions of 12 h,and the%PMN increased to 95.6%± 1.8%(p<0.05).Cortisol+E.coli group had fewer inflammatory cells than E.coli group at 6,24,and 48 h,and the%PMN decreased(p<0.05).(4)Compared with the control group,the endometrial epithelial cells of E.coli group showed damage and detachment at 12 h.The tissue of glandular structures was partially disrupted.Inflammatory cells infiltrated into the uterine glands in the lamina propria,part of the uterine gland structures were destroyed,and endometrial epithelial cells completely shedding within 24 to 72 h.Compared with the E.coli group,the cortisol+E.coli group had a more complete endometrial epithelial cell structure,and the phenomenon of damage and shedding was not obvious.In the lamina propria,the degree of inflammatory cells infiltration was slight.The results suggested that cortisol alleviated the abnormal changes of T,HR and RR of goats with E.coli-induced endometritis;reduced the number of peripheral blood leukocytes and%PMN in uterine secretions of goats;inhibited the inflammation of goat endometrium;reduced the damage and shedding of goat endometrial epithelial cells and the infiltration of inflammatory cells of the lamina propria.2.Effect of cortisol on gene expression of TLR4 and related inflammatory factors in postpartum does with E.coli-induced endometritisThe Toll-like receptor 4(TLR4),interleukin-?,IL-6,IL-8,tumor necrosis factor-?,cyclooxygenase-2 and inducible nitric oxide synthetase(iNOS)mRNA transcripts were detected using qPCR.The results showed that compared with the control group,the relative abundances of mRNA transcripts for TLR4 and pro-inflammatory cytokine in the E.coli group increased at 12 h(p<0.05).The relative abundances of mRNA transcripts for TLR4 and pro-inflammatory cytokine in cortisol+E.coli group were less than E.coli group(p<0.05),but still greater than control group(p<0.05).The results suggested that cortisol reduced the relative abundances of mRNA transcripts for TLR4,IL-1?,IL-6,IL-8,TNF-?,COX-2 and iNOS in goat endometrium with E.coli-induced endometritis.3.Effect of cortisol on MAPK and MyD88/NF-?B signaling pathways in postpartum does with E.coli-induced endometritisThe activations of NF-?B and MAPK signaling pathways were detected using Western blot procedures.The results showed that compared with the E.coli group at 0 h,the MyD88 abundance and the phosphorylation of ERK1/2,JNK,p38 MAPK,p65,and IKB? increased in E.coli group at 12 h(p<0.05).The MyD88 abundance and phosphorylation of ERK1/2,JNK,p38 MAPK,p65,and I?Ba in cortisol+E.coli group were less than E.coli group at 12 h(p<0.05).But there was no significant difference compared with 0 h.The results suggested that cortisol has an inhibitory effect on the innate immune response of goats with E.coli-induced endometritis.The effect may be achieved by inhibiting the MAPK and NF-?B signaling pathways.