Effect of Lactobacillus johnsonii Strain SQ0048 on the TLRs-MyD88/NF-κB Signaling Pathway in Bovine Vaginal Epithelial Cells.

Chao Cheng,Yanru Fu,Junxiang Mu,Qiaozhen Tian,Xiaohong Ma,Zhiguo Liu,Linchong Zhang,Zhenjun Li,Yanming Liu

doi:10.3389/fvets.2021.670949

Abstract

Vaginal inflammation is a common disease of the dairy cows' reproductive tract. Lactic acid bacteria can combat purulent inflammation caused by pathogenic bacteria and regulate the NF-κB signaling pathway mediated by toll-like receptors (TLRs) in the inflammatory response. We studied the effect of Lactobacillus johnsonii SQ0048, an isolate with antibacterial activity, on the NF-κB signaling pathway in cow vaginal epithelial cells. The expression levels of serial effectors related to the TLRs-MyD88/NF-κB signaling pathway (TLR2, TLR4, MyD88, IKK, NF-κB, IL-1β, IL-6, TNF-α, and IL-10) were measured with real-time polymerase chain reaction (RT-PCR), ELISA, and Western blot analyses. TLR2 and TLR4 were activated by SQ0048 cells, as noted by increased mRNA expression levels of TLR2 and TLR4 in SQ0048-treated bovine vaginal epithelial cells relative to control cells (P <0.01). SQ0048 treatment also significantly increased MyD88 and IKK expression, and activated NF-κB in vaginal epithelial cells (P <0.01). In addition, SQ0048 treatment also significantly increased mRNA expression levels of IL-1β, IL-6, and TNF-α, but decreased IL-10 mRNA expression levels (P <0.01). These data indicate that strain SQ0048 presence can improve the immune functions of cow vaginal epithelial cells by activating TLRs-MyD88/NF-κB signaling pathways. However, further in vivo studies are required to confirm these findings.

Highlights

Lactic acid bacteria (LAB) are the main bacteria in the healthy female reproductive tract of humans and other mammals such as cows [1]
The peptidoglycan of Lactobacillus can upregulate TLR2 receptors, participate in the innate immune response, and activate the TLR4 pathway [7]; it functions as a surveillance mechanism against pathogenic bacteria in the TLR4 pathway [8, 9]
The probiotic properties and antibacterial characteristics of LAB are closely related to the NF-κB signaling pathway [21]

Summary

Introduction

Lactic acid bacteria (LAB) are the main bacteria in the healthy female reproductive tract of humans and other mammals such as cows [1]. The production of cytokines related to inflammation is mediated by the NF-κB signaling pathway, which plays an important role in infection by pathogenic bacteria [3]. Some pathogen molecules, such as lipopolysaccharides, can be recognized by Toll-like receptors (TLRs) and they further activate NF-κB to stimulate the production of cytokines [4]. LAB control vaginal pathogenic bacteria in the female urogenital tracts by lowering pH and decreasing levels of hydrogen peroxide, and bacteriocins [5]. The IKK complex can inhibit NF-κB by controlling phosphorylation of the κB signaling pathway, which regulates cytokines to suppress inflammation under the stimulation of lactic acid bacteria [11]. Another study confirmed that LAB could inhibit TLR-4-linked NF-κB activation [12]

Methods

Results

Conclusion