β-Arrestin 2: a Negative Regulator of Inflammatory Responses in Polymorphonuclear Leukocytes

International Journal of Clinical and Experimental Medicine

George E. Tempel¹  Fahmin Basher¹  Keith T. Borg¹  Lou M. Luttrell¹  Hongkuan Fan¹  Basilia Zingarelli¹  Perry V. Halushka¹  James A. Cook¹ 

关键词: Polymorphonuclear leukocytes (PMN);    lipopolysaccharide (LPS);    β-arrestin 2;    adhesion receptors;   

DOI  :  

学科分类：医学（综合）

来源: e-Century Publishing Corporation

【 摘 要 】

Heterotrimeric Gi proteins have been previously implicated in signaling leading to inflammatory mediator production induced by bacterial lipopolysaccharide (LPS). β-arrestins are ubiquitously expressed proteins that alter G-protein-coupled receptors signaling. β-arrestin 2 plays a multifaceted role as a scaffold protein in regulating cellular inflammatory responses. Polymorphonuclear leukocytes (PMNs) activated by LPS induce inflammatory responses resulting in organ injury during sepsis. We hypothesized that β-arrestin 2 is a critical modulator of inflammatory responses in PMNs. To examine the potential role of β-arrestin 2 in LPS-induced cellular activation, we studied homozygous β-arrestin 2 (-/-), heterozygous (+/-), and wildtype (+/+) mice. PMNs were stimulated with LPS for 16h. There was increased basal TNFα and IL-6 production in the β-arrestin 2 (-/-) compared to both β-arrestin 2 (+/-) and (+/+) cells. LPS failed to stimulate TNFα production in the β-arrestin 2 (-/-) PMNs. However, LPS stimulated IL-6 production was increased in the β-arrestin 2 (-/-) cells compared to (+/+) cells. In subsequent studies, peritoneal PMN recruitment was increased 81% in the β-arrestin 2 (-/-) mice compared to (+/+) mice (p<0.05). β-arrestin 2 deficiency resulted in an augmented expression of CD18 and CD62L (p<0.05). In subsequent studies, β-arrestin 2 (-/-) and (+/+) mice were subjected to cecal ligation and puncture (CLP) and lung was collected and analyzed for myeloperoxidase activity (MPO) as index of PMNs infiltrate. CLP-induced MPO activity was significantly increased (p<0.05) in the β-arrestin 2 (-/-) compared to (+/+) mice. These studies demonstrate that β-arrestin 2 is a negative regulator of PMN activation and pulmomary leukosequestration in response to polymicrobial sepsis.

【 授权许可】

Unknown