A Friend in Need May Not be a Friend Indeed: Role of Microglia in Neurodegenerative Diseases

Inflammation plays a critical role in the progression of neurodegenerative diseases. Microglia are the resident macrophages of the central nervous system (CNS) which actively take part in the neuronal development of CNS and are involved in clearance of pathogens as well as cellular debris from the system upon insult to this organization. Chronic activation of microglia in neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS) as well as inflammatory conditions of CNS such as multiple sclerosis (MS) results in overall upregulation of pro-inflammatory cytokines and chemokines in the brain parenchyma. This compromises the neuronal health which further activates microglia by releasing death associated molecules such as neuromelanin, A peptides and cellular debris at the lesion site thereby forming a vicious cycle of disease advancement. Targeting microglial activation has proven to be a viable option in the treatment of inflammation related neurodegenerative diseases. This review will discuss the central position of inflammation and therapeutic strategies aiming to alleviate disease progression in some of the important inflammatory conditions of CNS.