Molecular Mechanisms of Lipopolysaccharide (LPS) Induced Inflammation in an Immortalized Ovine Luteal Endothelial Cell Line (OLENDO).

Aykut Gram,Mariusz P. Kowalewski

doi:10.3390/vetsci9030099

Aykut Gram, Mariusz P. Kowalewski

Open Access

https://doi.org/10.3390/vetsci9030099

Copy DOI

Journal: Veterinary sciences	Publication Date: Feb 24, 2022
Citations: 7	License type: CC BY 4.0

Affiliation: Erciyes University, University of Zurich

Abstract

Escherichia coli (E. coli) is the most common Gram-negative bacterium causing infection of the uterus or mammary gland and is one of the major causes of infertility in livestock. In those animals affected by E. coli driven LPS-mediated infections, fertility problems occur in part due to disrupted follicular and luteal functionality. However, the molecular mechanisms by which LPS induces inflammation, and specifically, the role of LPS in the disruption of capillary morphogenesis and endothelial barrier function remain unclear. Here, we hypothesized that LPS may lead to alterations in luteal angiogenesis and vascular function by inducing inflammatory reactions in endothelial cells. Accordingly, OLENDO cells were treated with LPS followed by evaluation of the expression of selected representative proinflammatory cytokines: NF-kB, IL6, IL8, TNFα, and ICAM 1. While TNFα was not affected by treatment with LPS, transcripts of NF-kB, IL6, and IL8 were affected in a dosage-dependent manner. Additionally, the activity of TLR2 and TLR4 was blocked, resulting in suppression of the LPS-induced expression of ICAM 1, NF-kB, IL6, and IL8. Inhibition of the PKA or MAPK/ERK pathways suppressed the LPS-stimulated expression of NF-kB, IL6, and IL8, whereas blocking the PKC pathway had the opposite effect. Furthermore, LPS-induced phosphorylation of Erk1 and Erk2 was inhibited when the TLR4 or MAPK/ERK pathways were blocked. Finally, LPS seems to induce inflammatory processes in OLENDO cells via TLR2 and TLR4, utilizing different signaling pathways.

Highlights

Bacterial infections of reproductive organs in dairy cows are common worldwide.Gram-negative bacteria, in particular Escherichia coli (E. coli), are the main cause of clinical metritis and mastitis and reduce reproductive performance in livestock [1,2,3]
Since the data obtained in our current study showed a normal distribution, to assess the effects of LPS treatment on the expression of TNFα, nuclear translocation of (NF)-kB, IL6, IL8, and intercellular adhesion molecule-1 (ICAM 1), a global comparison was performed by applying parametric one-way analysis of variance (ANOVA) with the statistical software program GraphPad 3.06
While TNFα was not affected by treatment with LPS (p = 0.3 for 6 h and p = 0.9 for 12 h, Figure 1A), NF-kB (p < 0.0001 for 6 h and p < 0.002 for 12 h, Figure 1B), IL6 (p < 0.0001 for both 6 h and 12 h, Figure 1C) and IL8 (p < 0.0001 for both 6 h and 12 h, Figure 1D), were affected in a dosage-dependent manner

Summary

Introduction

Bacterial infections of reproductive organs in dairy cows are common worldwide.Gram-negative bacteria, in particular Escherichia coli (E. coli), are the main cause of clinical metritis and mastitis and reduce reproductive performance in livestock [1,2,3]. As a result, inhibited follicular growth, reflected in disturbed ovarian cyclic activity, and lowered intrafollicular and circulating levels of estradiol (E2) are observed [3,4,5,6]. This is corroborated by both in vivo and in vitro observations demonstrating an LPS-dependent decrease in E2 production in bovine granulosa cells [13]. Administration of LPS in dairy cows reduces expression of the luteal steroidogenic acute regulatory (STAR) protein and 3β-hydroxysteroid dehydrogenase (HSD3B) [15]. Both corpus luteum (CL) size and luteal blood flow were reduced in diestric cows following the application of LPS [16]

Methods

Results

Discussion

Conclusion