PubMed: 27314526

Title
Inflammasome Involvement in Alzheimer's Disease.
Journal
Journal of Alzheimer's disease : JAD
Volume
54
Issue
None
Pages
45-53
Date
2016-06-15
Authors
Olsen I | Singhrao SK

Evidence 6cdcca2502

Of these, the NLRP3 inflammasome can be acti- vated via bacterial RNA species [3].

Evidence 6f1d819560

In AD, microglial cells and astrocytes express NLRP3, which in turn can detect A beta plaques and act by secreting caspase-1 to activate IL-1 beta and IL- 18 [23–25].

Evidence f64c854bc0

It is noteworthy that IL-1 beta and IL-18 can activate various cell types, par- ticularly astrocytes and microglia to induce additional cytokine release involving IL-1 beta , IL-6, and IL-18, and also nitric oxide (NO) synthase that can stimulate production of free radical NO, leading to the forma- tion of peroxynitrite that denatures DNA and impairs cellular energy pathways [48, 49].

Evidence 334f04e003

NO can also bring about apoptosis of hippocampal neurons via caspase- 3 activity [50] whereas astrocyte-secreted IL-1 beta can increase the production of APP and A beta from neu- rons [51–53] (Fig. 1).

Evidence 5cfe1d7a78

Additionally, it can induce phosphorylation of the tau protein and promote for- mation of neurofibrillary tangles through the mitogen activated protein kinases-p38 (MAPK-p38) stress pathway [22, 54].

Evidence ea96651f0d

Pattern recognition receptors such as the TLR4 receptor are expressed in the brain’s own immune cells like microglia and astrocytes that induce inflammation via cytokine secretion [38].

Evidence b465753ed9

This family serves several biological functions but if inappropriately secreted can lead to manifestation of depressive behaviors typ- ically associated with dementia onset and chronic neuroinflammation.

Evidence fe53494fb9

P2X7 expressed by microglial cells will also activate the NLP3 inflammasome [30, 32] and the expression of P2X7 is likely to be increased in AD brains [35].

Evidence 5b0187ced8

The NLRP3 inflammasome has a role in AD by increas- ing caspase-1 expression levels in AD brains [13, 23].

Evidence 00766c087d

Inflammasomes are responsible for the maturation of pro-inflammatory cytokines such as interleukin (IL)-1beta, IL-18, and IL-33 and activation of inflammatory cell death, pyroptosis.

Evidence 02fa5f5136

They appear to be involved in several pathological processes activated by microbes including Alzheimer’s disease (AD).

Evidence 334d1ae070

Post activation of the inflammasome, caspase 1 enzyme initiates the maturation of pro-inflammatory cytokines particularly interleukin (IL)-1beta, IL-18, and IL-33 [4] (Fig. 1),and inflammation mediated cell death occurs via the nucleotide-binding domain and leucine-rich repeat(NLR) family of proteins [5].

Evidence db965ce378

Both IL-1 beta and IL-18 are generated in their mature secreted form by caspase-1 through activa- tion of the inflammasome.

Evidence 9a17ad5639

In the NLRP3 inflammasome, the NLR pro- tein recruits the inflammasome-adaptor protein apoptosis-associated speck-like protein containing CARD (ASC), which in turn interacts with caspase- 1 leading to its activation [7].

Evidence ca95eaadda

Once activated, caspase-1 promotes the maturation of the proin- flammatory cytokines IL-1 beta , IL-18, and IL-33.

Evidence 3bddcbdaf7

However, IL- 18 can be derived as a byproduct from the activities of various extracellular enzymes such as protease 3, serine protease, elastase and cathepsin G [62–65].

Evidence cbab821135

Pro-inflammatory IL-18 increases AD-associated A beta deposition in human neuron-like cells in culture [55]. IL-18 also increases the expression of glycogen synthase kinase 3 beta (GSK-3 beta ) and cyclin-dependent kinase 5, both of which are involved in hyperphos- phorylation of the tau protein [56].

Evidence 4bc4f6a3c3

Increased levels of IL-1 beta and IL-18 have been detected in serum, cerebrospinal fluid, and brains of patients with AD and in other forms of dementia [42–46].

Evidence c75b48fc44

Both these studies indicated an important role of IL-18 in AD.

Evidence ad1aadca7a

P2X7 activation is followed by a number of downstream events, including release of pro-inflammatory mediators, cell death, and proliferation.

Evidence 8bd7a9e617

Longitudinal studies including that by Ide et al. [8] all agree that in AD, the presence of periodonti- tis appears to be associated with a marked increase in cognitive decline.

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