Microbial Infections Are a Risk Factor for Neurodegenerative Diseases

Abstract

Neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis, comprise a family of disorders characterized by progressive loss of nervous system function. Neuroinflammation is increasingly recognized to be associated with many neurodegenerative diseases but whether it is a cause or consequence of the disease process is unclear. Of growing interest is the role of microbial infections in inciting degenerative neuroinflammatory responses and genetic factors that may regulate those responses. Microbial infections cause inflammation within the central nervous system through activation of brain-resident immune cells and infiltration of peripheral immune cells. These responses are necessary to protect the brain from lethal infections but may also induce neuropathological changes that lead to neurodegeneration. This review discusses the molecular and cellular mechanisms through which microbial infections may increase susceptibility to neurodegenerative diseases. Elucidating these mechanisms is critical for developing targeted therapeutic approaches that prevent the onset and slow the progression of neurodegenerative diseases.

The Role of Human Herpesvirus 6 Infection in Alzheimer’s Disease Pathogenicity—A Theoretical Mosaic

“…Recent research suggests the implication of several micro-organisms in the pathogenesis of non-communicable diseases [ 58 ]. While the complete pathophysiological mechanism is unknown, it is clear that viral pathogens can be effective triggers that, in combination with a favorable genetic and phenotypic environment, lead to neurodegeneration [ 59 ]. Up to now, only common immunopathological mechanisms of chronic HHV-6 infection and neuroinflammation that lead to pathological conditions such as AD have been described.…”

Neuropathological Aspects of SARS-CoV-2 Infection: Significance for Both Alzheimer’s and Parkinson’s Disease

“…It is worth noting that HSV-1 infections are common, and that the virus can persist in a latent form within the neurons of its human host. Therefore, viruses may cause damage in vulnerable brain areas leading to neurodegenerative disease ( Lotz et al, 2021 ; Sait et al, 2021 ).…”

“…Older people comprise the section of the population most prone to developing neurodegenerative diseases ( Hou et al, 2019 ) and present with more severe clinical reaction to COVID-19 ( Lebrasseur et al, 2021 ). In addition, lifestyle and preexisting conditions such as trauma, infection, metabolic disease, and stress can accelerate the onset and progression of neurodegenerative diseases ( Graham and Sharp, 2019 ; Madore et al, 2020 ; Lotz et al, 2021 ).…”

Infectious Agents as Potential Drivers of α‐Synucleinopathies

“…No pooled analysis was performed for Borrelia burgdorferi, 116,120,121 Nocardia asteroides, 122 Chlamydia pneumoniae, 116 tuberculosis, 123 or diphtheria. 124 Finally, in the current context of the SARS-CoV-2 pandemic, concern about the effect of the virus on the onset or evolution of PD is increasing, 91,103,108,[125][126][127] and long-term effects should be carefully monitored.…”