Budesonide epimer R, LAU-8080 and phenyl butyl nitrone synergistically repress cyclooxygenase-2 induction in [IL-1β+Aβ42]-stressed human neural cells

Uncovering the Oxidative Stress Mechanisms and Targets in Alzheimer's Disease by Integrating Phenotypic Screening Data and Polypharmacology Networks

Background

The oxidative stress hypothesis is challenging the dominant position of amyloid-β (Aβ) in the field of understanding the mechanisms of Alzheimer's disease (AD), a complicated and untreatable neurodegenerative disease.

Objective

The goal of the present study was to uncover the oxidative stress mechanisms causing AD, as well as the potential therapeutic targets and neuroprotective drugs against oxidative stress mechanisms.

Methods

In this study, a systematic workflow combining pharmacological experiments and computational prediction was proposed. 222 drugs and natural products were collected first and then tested on SH-SY5Y cells to obtain phenotypic screening data on neuroprotection. The preliminary screening data were integrated with drug-target interactions (DTIs) and multi-scale biomedical data, which were analyzed with statistical tests and gene set enrichment analysis. A polypharmacology network was further constructed for investigation.

Results

340 DTIs were matched in multiple databases, and 222 cell viability ratios were calculated for experimental compounds. We identified significant potential therapeutic targets based on oxidative stress mechanisms for AD, including NR3C1, SHBG, ESR1, PGR, and AVPR1A, which might be closely related to neuroprotective effects and pathogenesis. 50% of the top 14 enriched pathways were found to correlate with AD, such as arachidonic acid metabolism and neuroactive ligand-receptor interaction. Several approved drugs in this research were also found to exert neuroprotective effects against oxidative stress mechanisms, including beclometasone, methylprednisolone, and conivaptan.

Conclusion

Our results indicated that NR3C1, SHBG, ESR1, PGR, and AVPR1A were promising therapeutic targets and several drugs may be repurposed from the perspective of oxidative stress and AD.

Synergism in the repression of COX-2- and TNFalpha-induction in platelet activating factor-stressed human neural cells

Platelet activating factor (PAF; beta-acetyl-gamma-O-hexadecyl-l-alpha-phosphatidylcholine) triggers a rapid pro-inflammatory gene expression program in primary cultures of human neural (HN) cells. Two genes and gene products consistently induced after PAF treatment are the cytosoluble prostaglandin synthase cycloooxygenase-2 (COX-2) and the pro-apoptotic tumor necrosis factor alpha (TNFalpha). Both of these mediators are associated with the activation of inflammatory signaling, neural cell dysfunction, apoptosis and brain cell death, and both have been found to be up-regulated after brain injury in vivo. In this study we investigated the effects of the non-halogenated synthetic glucocorticoid budesonide epimer R (BUDeR), the novel PAF antagonist LAU-0901, and the electron spin trap and free radical scavenger phenyl butyl nitrone (PBN), upon early COX-2 and TNFalpha gene activation and prostaglandin E(2) (PGE(2)) release in PAF-stressed primary HN cells. The data indicate that these three biochemically unrelated classes of inflammatory repressors act synergistically in modulating PAF-induced up-regulation of COX-2, TNFalpha, and PGE(2) by quenching oxidative stress or inflammatory signaling, resulting in increased HN cell survival. These, or analogous classes of compounds, may be useful in the design of more effective combinatorial pharmacotherapeutic strategies in the treatment of complex neuro-inflammatory disorders.

Molecular mechanisms for Alzheimer's disease: implications for neuroimaging and therapeutics

Alzheimer's disease is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are beta-amyloid (Abeta) plaques, neurofibrillary tangles, synaptic loss and reactive gliosis. The current therapeutic effort is directed towards developing drugs that reduce Abeta burden or toxicity by inhibiting secretase cleavage, Abeta aggregation, Abeta toxicity, Abeta metal interactions or by promoting Abeta clearance. A number of clinical trials are currently in progress based on these different therapeutic strategies and they should indicate which, if any, of these approaches will be efficacious. Current diagnosis of Alzheimer's disease is made by clinical, neuropsychologic and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography and magnetic resonance imaging is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of Alzheimer's disease. Functional neuroimaging techniques such as functional magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography and single photon emission computed tomography, possibly in conjunction with other related Abeta biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of Alzheimer's disease, as well as in assessing prognosis. With the advent of new therapeutic strategies there is increasing interest in the development of magnetic resonance imaging contrast agents and positron emission tomography and single photon emission computed tomography radioligands that will permit the assessment of Abeta burden in vivo.

Cholesterol and 24S-hydroxycholesterol trafficking in Alzheimer's disease

Cholesterol and the cholesterol oxide 24S-hydroxycholesterol (24S-HC) are highly enriched in the human CNS. Clinical, genetic, neurochemical and epidemiological evidence continue to support dysfunctional cholesterol metabolism as an important contributing factor driving the development and/or progression of Alzheimer's disease (AD) neuropathology. Cholesterol overabundance in the brain plasma membrane lipid- raft domains, appears to be fundamental to the generation of the more neurotoxic forms of amyloid-beta (Abeta) peptide from beta-amyloid holoprotein precursor. 24S-HC may have a pivotal role in promoting altered inflammatory signaling, apoptotic genetic responses and AD-type change. In clinical studies, cholesterol-lowering statins, nonsteroidal anti-inflammatory drugs, cholesterol absorption/transport inhibitors and related modulators of cholesterol trafficking have demonstrated some pharmacological benefit for the treatment of AD, but overall their efficacy at slowing the cognitive decline and the progression of AD remains controversial and open to question.