Different Modulating Effects of Adenosine on Neonatal and Adult Polymorphonuclear Leukocytes

Pei-Chen Hou,Te-Yao Hsu,Hong-Ren Yu,Kuender D Yang,Li-Yan Lin,Wen-Hsin Cheng,Chia-Yu Ou,Ho-Chang Kuo,Yi-Jyun Jheng,Lin Wang,Jiunn-Ming Sheen

doi:10.1100/2012/387923

Pei-Chen Hou, Te-Yao Hsu + Show 9 more

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https://doi.org/10.1100/2012/387923

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Abstract

Polymorphonuclear leukocytes (PMNs) are the major leukocytes in the circulation and play an important role in host defense. Intact PMN functions include adhesion, migration, phagocytosis, and reactive oxygen species (ROS) release. It has been known for a long time that adenosine can function as a modulator of adult PMN functions. Neonatal plasma has a higher adenosine level than that of adults; however, little is known about the modulating effects of adenosine on neonatal PMNs. The aim of this study was to investigate the effects of adenosine on neonatal PMN functions. We found that neonatal PMNs had impaired adhesion, chemotaxis, and ROS production abilities, but not phagocytosis compared to adult PMNs. As with adult PMNs, adenosine could suppress the CD11b expressions of neonatal PMNs, but had no significant suppressive effect on phagocytosis. In contrast to adult PMNs, adenosine did not significantly suppress chemotaxis and ROS production of neonatal PMNs. This may be due to impaired phagocyte reactions and a poor neonatal PMN response to adenosine. Adenosine may not be a good strategy for the treatment of neonatal sepsis because of impaired phagocyte reactions and poor response.

Highlights

Polymorphonuclear leukocytes (PMNs) are the major leukocytes in the circulation, and they play an important role in host defense
We evaluated the effects of adenosine on neonatal PMN functions
Our findings are in agreement with previous reports that neonatal PMNs are impaired in adhesion, chemotaxis, and reactive oxygen species (ROS) production abilities, but not phagocytosis compared to adult PMNs [14,15,16,17,18]

Summary

Introduction

Polymorphonuclear leukocytes (PMNs) are the major leukocytes in the circulation, and they play an important role in host defense. PMNs, migrating to the infection site and evoking inflammatory responses, are critical components of innate immune responses. PMNs typically use selectin receptors to form rolling attachments on the vessel wall. Β2-integrin CD11b/CD18 is rapidly activated allowing leukocytes to firmly adhere to endothelial cells and migrate through the blood vessels toward sites of inflammation, following chemical signals in a process called chemotaxis [1]. PMNs are phagocytes, capable of ingesting microorganisms. They can internalize and kill many microbes, with each phagocytic event resulting in the formation of a phagosome into which reactive oxygen species (ROS) and hydrolytic enzymes are secreted

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