Baicalin plays an anti-inflammatory role through reducing nuclear factor-κB and p38 phosphorylation in S. aureus-induced mastitis

doi:10.1016/j.intimp.2013.03.006

International Immunopharmacology

Volume 16, Issue 2, June 2013, Pages 125-130

https://doi.org/10.1016/j.intimp.2013.03.006 Get rights and content

Highlights

•
Baicalin attenuated inflammatory cell infiltration in S. aureus-induced mastitis.
•
Baicalin decreased levels of TNF-α, IL-β, and IL-6.
•
Baicalin downregulated mRNA expression and phosphorylation of NF-κB and p38.

Abstract

Mastitis is an inflammatory disease caused by microbial infection. Staphylococcus aureus is the major etiological microorganism responsible for both clinical and subclinical mastitis in dairy cows. A mouse model of S. aureus mastitis is available. Baicalin is isolated from Scutellaria and is known to have anti-inflammatory properties. This study was designed to evaluate the effects of baicalin in S. aureus mastitis. In the present study, the mouse model was infected with S. aureus to cause mammary gland inflammation. Baicalin treatment was administered from 6 h until 24 h after infection. Baicalin significantly attenuated inflammatory cell infiltration and decreased levels of TNF-α, IL-β, and IL-6. Further studies revealed that baicalin downregulated phosphorylation of NF-κB and p38 in the mammary gland with S. aureus mastitis. Our results demonstrated that baicalin reduced the expression of the proinflammatory cytokines TNF-α, IL-β, and IL-6 by inhibiting NF-κB and p38 phosphorylation and mRNA expression.

Introduction

Mastitis is a prevalent disease in the dairy industry [1]. It continues to be responsible for large economic losses even though research and preventative measures have been intensive for decades. Mastitis is defined as inflammation of the mammary gland which results principally from pathogenic microorganism invasion, including the gram-positive bacteria, Staphylococcus aureus [2].

S. aureus is classified as an opportunistic bacterial pathogen that can infect diverse hosts [3]. S. aureus bovine mastitis constitutes a major challenge to dairy producers. The sick dairy cow displays a series of clinical symptoms, such as a red, swollen, and painful udder; fever; and depression [4], and the condition can even be fatal. More research to develop new prophylactic and therapeutic approaches for S. aureus bovine mastitis is needed.

The costs associated with experimental S. aureus mastitis in the cow are prohibitive; thus, the use of smaller animal models is required. A mouse model of S. aureus mastitis was first described by Chandler in 1970 [5]. Anderson and Chandler further characterized this model until the mid-1980s [6]. Since 2000, S. aureus has been widely employed in studies using a mouse model of microbial mastitis. Thus, we conducted our study using the mouse model of S. aureus mastitis.

Baicalin (Fig. 1), the major active constituent of the isolated root of Scutellaria baicalensis, is used as an anti-inflammatory agent in China, Japan and Korea [7], [8]. Studies have shown that it has multiple biological properties, including anti-oxidant [9], anti-tumor [10], anti-ischemic, and anti-inflammatory activities [11]. The anti-inflammatory activity of baicalin has been associated with NF-κB, as shown in various acute and chronic inflammation models [12], most of which are induced by LPS. S. aureus is a gram-positive bacterium. LPS is a component of the outer membrane of gram-negative bacteria. There are many differences between these bacteria in regards to inducing inflammation, and there is little information about the anti-inflammatory effects of baicalin in S. aureus-induced mastitis. Thus, this study was conducted to determine the effects of baicalin on the inflammatory response in a mouse model of S. aureus mastitis and to examine the mechanism of action involved.

Section snippets

Animals

In total, 30 adult female BALB/c mice (6–8 weeks old, weighing 40–45 g) were used, provided by the Center of Experimental Animals of Baiqiuen Medical College, Jilin University, China. Procedures were conducted according to the US NIH Guide for the Care and Use of Laboratory Animals, and approved by the Institutional Animal Care and Use Committee of Jilin University.

Drug administration and experimental groups

Baicalin was dissolved in physiological saline, and 24 h after inducing infection in the mammary gland, it was injected three times,

Histopathological changes

Mammary gland tissues were harvested at 24 h after inducing infection and baicalin treatment. Tissues sections were subjected to hematoxylin and eosin staining. No pathological change was observed in CG (Fig. 2A). In MG (Fig. 2B), the lobules of the mammary gland were not complete; and the acinus of the mammary was damaged. Many of the epithelial cells were destroyed. There were many inflammatory cells, including neutrophils and macrophages, in the mammary tissues. However, these

Discussion

Bovine mastitis, mainly caused by microbial infections, is an inflammatory disease [16], causing great economic losses [17]. It has two types, clinical and subclinical mastitis [18]. S. aureus is a major etiological microorganism, responsible for both clinical and subclinical mastitis in dairy cows [19]. To date, there is no efficacious treatment for S. aureus mastitis.

The mouse model of S. aureus mastitis (MMSAM) is valuable because it requires only standard animal care facilities and basic

Acknowledgments

This work was supported by grants from the National Natural Science Foundation of China (Nos. 30972225, 30771596, and 31130053) and the Research Fund for the Doctoral Program of Higher Education of China (No. 20110061130010).

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Baicalin plays an anti-inflammatory role through reducing nuclear factor-κB and p38 phosphorylation in S. aureus-induced mastitis

Highlights

Abstract

Introduction

Section snippets

Animals

Drug administration and experimental groups

Histopathological changes

Discussion

Acknowledgments

Microbes Infect

Vet Clin North Am Food Anim Pract

J Ethnopharmacol

Pharmacol Res

Eur J Pharmacol

Mech Ageing Dev

J Dairy Sci

Comp Immunol Microbiol Infect Dis

Res Vet Sci

Comp Biochem Physiol A Mol Integr Physiol

Microbes Infect

Int Immunopharmacol

Vet Microbiol

J Surg Res

Staphylococcus aureus: an introduction

Semin Immunopathol

Mouse models to study the pathogenesis and control of bovine mastitis. A review

Vet Q

Experimental bacterial mastitis in the mouse

J Med Microbiol

Inflationary language — model

Vet Rec