Systemic Inflammation Predicts Alzheimer Pathology in Community Samples without Dementia

Association between dietary magnesium intake, inflammation, and neurodegeneration

BACKGROUND

Consistent evidence shows that magnesium (Mg) intake is associated with lower blood pressure (BP), and that lower BP is associated with improved cerebral health. However, recent findings indicate that the positive effect of dietary Mg intake on cerebral health is not mediated by a decrease in BP. As Mg's anti-inflammatory action is a plausible alternative mechanism, the objective of this study was to investigate the associations between Mg intake and inflammation to determine whether it mediates any neuroprotective effect.

METHODS

Participants from the UK Biobank (n = 5775, aged 40-73 years, 54.7% female) were assessed for dietary magnesium using an online food questionnaire, brain and white matter lesion (WML) volumes were segmented with FreeSurfer software, and inflammation markers including high-sensitivity C-reactive protein (hs-CRP), leukocyte, erythrocyte count, and Glycoprotein acetylation (GlycA) were measured using specific laboratory techniques such as immunoturbidimetry, automated cell counting, and nuclear magnetic resonance. Hierarchical linear regression models were performed to investigate the association between dietary Mg, and inflammatory markers and between dietary Mg, brain and WMLs volumes. Mediation analysis was performed to test a possible mediation role of inflammation on the association between dietary Mg and brain and WMLs volumes.

RESULTS

Higher dietary Mg intake was associated with lower inflammation: hs-CRP level (- 0.0497%; 95% confidence interval [CI] - 0.0497%,  - 0.0199%) leukocytes count (- 0.0015%; 95%CI - 0.00151%,  - 0.0011%), and GlycA (- 0.0519%; 95%CI - 0.1298%,  - 0.0129%). Moreover, higher dietary Mg intake was associated with larger grey matter volume (0.010%; 95%CI 0.004%, 0.017%), white matter volume (0.012%; 95%CI 0.003,  0.022) and right hippocampal volume (0.002%; 95%CI 0.0007, -0.0025%). Lower hs-CRP levels mediated the positive association between higher dietary Mg intake and larger grey matter volume.

CONCLUSIONS

The anti-inflammatory effects of dietary Mg intake in the general population, appears to mediate its neuroprotective effect.

Cognitive Function Is Associated with the Genetically Determined Efficiency of DNA Repair Mechanisms

Several modifiable risk factors for neurodegeneration and dementia have been identified, although individuals vary in their vulnerability despite a similar risk of exposure. This difference in vulnerability could be explained at least in part by the variability in DNA repair mechanisms' efficiency between individuals. Therefore, the aim of this study was to test associations between documented, prevalent genetic variation (single nucleotide polymorphism, SNP) in DNA repair genes, cognitive function, and brain structure. Community-living participants (n = 488,159; 56.54 years (8.09); 54.2% female) taking part in the UK Biobank study and for whom cognitive and genetic measures were available were included. SNPs in base excision repair (BER) genes of the bifunctional DNA glycosylases OGG1 (rs1052133, rs104893751), NEIL1 (rs7402844, rs5745906), NEIL2 (rs6601606), NEIL3 (rs10013040, rs13112390, rs13112358, rs1395479), MUTYH (rs34612342, rs200165598), NTHL1 (rs150766139, rs2516739) were considered. Cognitive measures included fluid intelligence, the symbol-digit matching task, visual matching, and trail-making. Hierarchical regression and latent class analyses were used to test the associations between SNPs and cognitive measures. Associations between SNPs and brain measures were also tested in a subset of 39,060 participants. Statistically significant associations with cognition were detected for 12 out of the 13 SNPs analyzed. The strongest effects amounted to a 1-6% difference in cognitive function detected for NEIL1 (rs7402844), NEIL2 (rs6601606), and NTHL1 (rs2516739). Associations varied by age and sex, with stronger effects detected in middle-aged women. Weaker associations with brain measures were also detected. Variability in some BER genes is associated with cognitive function and brain structure and may explain variability in the risk for neurodegeneration and dementia.

The Role of TNF-α in Alzheimer's Disease: A Narrative Review

This review analyzes the role of TNF-α and its increase in biological fluids in mild cognitive impairment, and Alzheimer's disease (AD). The potential inhibition of TNF-α with pharmacological strategies paves the way for preventing AD and improving cognitive function in people at risk for dementia. We conducted a narrative review to characterize the evidence in relation to the involvement of TNF-α in AD and its possible therapeutic inhibition. Several studies report that patients with RA and systemic inflammatory diseases treated with TNF-α blocking agents reduce the probability of emerging dementia compared with the general population. Animal model studies also showed interesting results and are discussed. An increasing amount of basic scientific data and clinical studies underscore the importance of inflammatory processes and subsequent glial activation in the pathogenesis of AD. TNF-α targeted therapy is a biologically plausible approach for cognition preservation and further trials are necessary to investigate the potential benefits of therapy in populations at risk of developing AD.

Role of de novo lipogenesis in inflammation and insulin resistance in alzheimer's disease

Patients with Alzheimer's disease (AD) display both peripheral tissue and brain insulin resistance, the later could be a potential risk factor for cognitive dysfunction. While certain degree of inflammation is required for inducing insulin resistance, underlying mechanism(s) remains unclear. Evidence from diverse research domains suggest that elevated intracellular fatty acids of de novo pathway can induce insulin resistance even without triggering inflammation; however, the effect of saturated fatty acids (SFAs) could be detrimental due the development of proinflammatory cues. In this context, evidence suggest that while lipid/fatty acid accumulation is a characteristic feature of brain pathology in AD, dysregulated de novo lipogenesis could be a potential source for lipid/fatty acid accumulation. Therefore, therapies aimed at regulating de novo lipogenesis could be effective in improving insulin sensitivity and cognitive function in patients with AD.

Dietary magnesium intake is related to larger brain volumes and lower white matter lesions with notable sex differences

PURPOSE

To examine the association between dietary magnesium (Mg) intake and brain volumes and white matter lesions (WMLs) in middle to early old age.

METHODS

Participants (aged 40-73 years) from UK Biobank (n = 6001) were included and stratified by sex. Dietary Mg was measured using an online computerised 24 h recall questionnaire to estimate daily Mg intake. Latent class analysis and hierarchical linear regression models were performed to investigate the association between baseline dietary Mg, Mg trajectories, and brain volumes and WMLs. Associations between baseline Mg, and baseline blood pressure (BP) measures, and baseline Mg, Mg trajectories and BP changes (between baseline and wave 2) were also investigated to assess whether BP mediates the link between Mg intake and brain health. All analyses controlled for health and socio-demographic covariates. Possible interactions between menopausal status and Mg trajectories in predicting brain volumes and WMLs were also investigated.

RESULTS

On average, higher baseline dietary Mg intake was associated with larger brain volumes (gray matter [GM]: 0.001% [SE = 0.0003]; left hippocampus [LHC]: 0.0013% [SE = 0.0006]; and right hippocampus [RHC]: 0.0023% [SE = 0.0006]) in both men and women. Latent class analysis of Mg intake revealed three classes: "high-decreasing" (men = 3.2%, women = 1.9%), "low-increasing" (men = 1.09%, women = 1.62%), and "stable normal" (men = 95.71%, women = 96.51%). In women, only the "high-decreasing" trajectory was significantly associated with larger brain volumes (GM: 1.17%, [SE = 0.58]; and RHC: 2.79% [SE = 1.11]) compared to the "normal-stable", the "low-increasing" trajectory was associated with smaller brain volumes (GM: - 1.67%, [SE = 0.30]; white matter [WM]: - 0.85% [SE = 0.42]; LHC: - 2.43% [SE = 0.59]; and RHC: - 1.50% [SE = 0.57]) and larger WMLs (1.6% [SE = 0.53]). Associations between Mg and BP measures were mostly non-significant. Furthermore, the observed neuroprotective effect of higher dietary Mg intake in the "high-decreasing" trajectory appears to be greater in post-menopausal than pre-menopausal women.

CONCLUSIONS

Higher dietary Mg intake is related to better brain health in the general population, and particularly in women.

Bisdemethoxycurcumin (BDC)-Loaded H-Ferritin-Nanocages Mediate the Regulation of Inflammation in Alzheimer's Disease Patients

BACKGROUND

Bisdemethoxycurcumin (BDC) might be an inflammation inhibitor in Alzheimer's Disease (AD). However, BDC is almost insoluble in water, poorly absorbed by the organism, and degrades rapidly. We thus developed a new nanoformulation of BDC based on H-Ferritin nanocages (BDC-HFn).

METHODS

We tested the BDC-HFn solubility, stability, and ability to cross a blood-brain barrier (BBB) model. We tested the effect of BDC-HFn on AD and control (CTR) PBMCs to evaluate the transcriptomic profile by RNA-seq.

RESULTS

We developed a nanoformulation with a diameter of 12 nm to improve the solubility and stability. The comparison of the transcriptomics analyses between AD patients before and after BDC-HFn treatment showed a major number of DEG (2517). The pathway analysis showed that chemokines and macrophages activation differed between AD patients and controls after BDC-HFn treatment. BDC-HFn binds endothelial cells from the cerebral cortex and crosses through a BBB in vitro model.

CONCLUSIONS

Our data showed how BDC-Hfn could improve the stability of BDC. Significant differences in genes associated with inflammation between the same patients before and after BDC-Hfn treatment have been found. Inflammatory genes that are upregulated between AD and CTR after BDC-HFn treatment are converted and downregulated, suggesting a possible therapeutic approach.