[Frontiers in Bioscience S3, 869-883, June 1, 2011]

Microglia-friend or foe

Hui Zhang1,2, Fu-Wu Wang1,2, lin-Li Yao1,2, Ai-Jun Hao1,2

1Key Laboratory of the Ministry of Education for Experimental Teratology, Department of Histology and Embryology, Shandong University School of Medicine, No.44, Wenhua Xi Road, Jinan, Shandong, 250012, PR China, 2Shandong Provincial Key Laboratory of Mental Disorders, Department of Histology and Embryology, Shandong University School of Medicine, No.44, Wenhua Xi Road, Jinan, Shandong, 250012, PR China

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Multi-faceted functions of activated microglia in CNS inflammation, neurogenesis and brain tumor
3.1. Microglia in neuroinflammation
3.1.1. Neuroprotective microglia
3.1.1.1. Neurotrophic factors
3.1.1.2. Anti-inflammatory factor
3.1.1.3. Microglial motility and phagocytosis
3.1.2. Neurotoxic microglia
3.1.2.1. Pro-inflammatory cytokines
3.1.2.2. Reactive oxygen and nitrogen species
3.1.2.3. Glutamate
3.2. Microglia in neurogenesis
3.2.1. Proinflammatory cytokines and their dual role in neurogenesis
3.2.1.1. IL-6 and its dual role in neurogenesis
3.2.1.2. TNF-a and its dual role in neurogenesis
3.2.1.3. IL-1b and its dual role in neurogenesis
3.2.1.4. IFN-g and its dual role in neurogenesis
3.2.2. Nitric oxide and its dual role in neurogenesis
3.2.3. Effect of chemokines and chemokine receptors on the neurogenesis
3.3. Microglia in brain tumor
3.3.1. Anti-tumor activity
3.3.2. Pro-tumor activity
3.3.3. Therapeutic potential of microglia activation in brain tumor
4. Conclusion
5. Acknowledgments
6. Reference

1. ABSTRACT

Microglia, as the immune effectors in the central nervous system, respond to pathological conditions and participate in the initiation and progression of neurological disorders such as inflammation and brain tumor by releasing potential neurotrophic or cytotoxic molecules, presenting the antigen to T cell and interacting with brain tumor. Evidences also suggest that microglia are capable of promoting or inhibiting the proliferation and differentiation of neural stem cells by secreting series of biologically active molecules. In this review, we focus on three aspects-inflammation, neurogensis and brain tumor to illustrate the multi-faceted activities of microglia in the normal and pathologic brain.