Modulating neuroinflammation in neurodegeneration-related dementia: can microglial toll-like receptors pull the plug?

• Published in: Metabolic brain disease 2021-06, Vol.36 (5), p.829-847
• Main Authors: Tiwari, Rohit Kumar, Moin, Afrasim, Rizvi, Syed Mohd Danish, Shahid, Syed Monowar Alam, Bajpai, Preeti
• Format: Article
• Language: English
• Subjects: Animals; Biochemistry; Biomedical and Life Sciences; Biomedicine; Brain - metabolism; Brain - pathology; Central nervous system; Chemokines; Crosstalk; Cyclic nucleotides; Cytokines; Dementia; Dementia - metabolism; Dementia - pathology; Dementia disorders; Feedback loops; Free radicals; Humans; Immune response; Immune system; Inflammation; Inflammation - metabolism; Inflammation - pathology; Inflammatory response; Intestinal microflora; Metabolic Diseases; Microbiota; Microglia; Microglia - metabolism; Microglia - pathology; Nerve Degeneration - metabolism; Nerve Degeneration - pathology; Neurodegeneration; Neurology; Neurosciences; Nucleotides; Older people; Oncology; Parkinson's disease; Positive feedback; Proteins; Receptors; Review Article; Toll-like receptors; Toll-Like Receptors - metabolism
• ISSN: 0885-7490; 1573-7365; 1573-7365
• DOI: 10.1007/s11011-021-00696-6

Neurodegeneration-associated dementia disorders (NADDs), namely Alzheimer and Parkinson diseases, are developed by a significant portion of the elderly population globally. Extensive research has provided critical insights into the molecular basis of the pathological advancements of these diseases, but an efficient curative therapy seems elusive. A common attribute of NADDs is neuroinflammation due to a chronic inflammatory response within the central nervous system (CNS), which is primarily modulated by microglia. This response within the CNS is positively regulated by cytokines, chemokines, secondary messengers or cyclic nucleotides, and free radicals. Microglia mediated immune activation is regulated by a positive feedback loop in NADDs. The present review focuses on evaluating the crosstalk between inflammatory mediators and microglia, which aggravates both the clinical progression and extent of NADDs by forming a persistent chronic inflammatory milieu within the CNS. We also discuss the role of the human gut microbiota and its effect on NADDs as well as the suitability of targeting toll-like receptors for an immunotherapeutic intervention targeting the deflation of an inflamed milieu within the CNS.