Salivary inflammatory biomarkers are predictive of mild cognitive impairment and Alzheimer's disease in a feasibility study

Plasma Proteomic Biomarkers in Alzheimer's Disease and Cardiovascular Disease: A Longitudinal Study

The co-occurrence of Alzheimer's disease (AD) and cardiovascular diseases (CVDs) in older adults highlights the necessity for the exploration of potential shared risk factors. A total of 566 adults were selected from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, including 111 individuals with AD, 383 with mild cognitive impairment (MCI), and 410 with CVD. The multivariable linear mixed model (LMM) was used to investigate the associations of AD and CVD with longitudinal changes in 146 plasma proteomic biomarkers (measured at baseline and the 12-month follow-up). The LMM showed that 48 biomarkers were linked to AD and 46 to CVD (p < 0.05). Both AD and CVD were associated with longitudinal changes in 14 biomarkers (α1Micro, ApoH, β2M, BNP, complement C3, cystatin C, KIM1, NGAL, PPP, TIM1, THP, TFF3, TM, and VEGF), and both MCI and CVD were associated with 12 biomarkers (ApoD, AXL, BNP, Calcitonin, CD40, C-peptide, pM, PPP, THP, TNFR2, TTR, and VEGF), suggesting intricate connections between cognitive decline and cardiovascular health. Among these, the Tamm Horsfall Protein (THP) was associated with AD, MCI, CVD, and APOE-ε4. This study provides valuable insights into shared and distinct biological markers and mechanisms underlying AD and CVD.

The Link Between Matrix Metalloproteinases and Alzheimer's Disease Pathophysiology

Alzheimer's disease (AD) is a major contributor to dementia and the most common neurodegenerative disorder. In AD pathophysiology, matrix metalloproteinases (MMPs)-proteolytic enzymes, best known to be responsible for remodeling and degradation of the extracellular matrix-were suggested to play an important role. Due to the diverse nature of the published data and frequent inconsistent results presented in available papers, it was considered essential to analyze all aspects of MMP literature with respect to AD pathophysiology and attempt to outline a unifying concept for understanding their role in AD. Thus, the main contribution of this review article is to summarize the most recent research on the participation of MMP in AD pathophysiology obtained using the cell cultures to understand the molecular principles of their action. Furthermore, an updated comprehensive view regarding this topic based exclusively on papers from human studies is provided as well. It can be concluded that determining the exact role of any particular MMPs in the AD pathophysiology holds promise for establishing their role as potential biomarkers reflecting the severity or progression of this disease or for developing new therapeutic agents targeting the processes that lead to AD.

Salivary Biomarkers for Alzheimer's Disease: A Systematic Review with Meta-Analysis

Alzheimer's Disease (AD) is the most common neurodegenerative disease which manifests with progressive cognitive impairment, leading to dementia. Considering the noninvasive collection of saliva, we designed the systematic review to answer the question "Are salivary biomarkers reliable for the diagnosis of Alzheimer's Disease?" Following the inclusion and exclusion criteria, 30 studies were included in this systematic review (according to the PRISMA statement guidelines). Potential biomarkers include mainly proteins, metabolites and even miRNAs. Based on meta-analysis, in AD patients, salivary levels of beta-amyloid42 and p-tau levels were significantly increased, and t-tau and lactoferrin were decreased at borderline statistical significance. However, according to pooled AUC, lactoferrin and beta-amyloid42 showed a significant predictive value for salivary-based AD diagnosis. In conclusion, potential markers such as beta-amyloid42, tau and lactoferrin can be detected in the saliva of AD patients, which could reliably support the early diagnosis of this neurodegenerative disease.

Effects of Zinc Supplementation on Inflammatory and Cognitive Parameters in Middle-Aged Women with Overweight or Obesity

Obesity has been linked to cognitive decline and adverse effects on brain health. Zinc (Zn) is a mineral with important metabolic functions that can modulate obesity-related neurological impairment. Thus, the present study aimed to evaluate the effects of 12 weeks of Zn supplementation on the inflammatory profile, cognitive function, and mood of overweight or obese women through a double-blind, placebo-controlled study. The study included 42 women aged between 40 and 60, randomly divided into two groups: Zn supplementation (30 mg/day) or placebo for 12 weeks. Data regarding sociodemographic, anthropometric, dietary, and physical activity were collected. Mini-mental state examination (MMSE), verbal fluency test, clock drawing test, and Stroop test were performed. Anxiety and depression symptoms were assessed using the Beck anxiety inventory and the BDI-II, respectively. Saliva samples were collected to evaluate IL-1β, IL-6, TNF-α, insulin, nitrite, and Zn levels. Of the 42 participants (mean age 49.58 ± 6.46 years), 32 were included in the study analyses. Changes in body weight and macronutrient consumption were not different between placebo and Zn supplementation groups. Cognitive scores on the MMSE and Stroop tests were higher in the Zn supplementation group than in the placebo group. Salivary levels of IL-1b and Zn increased in the Zn group compared to placebo. There was no significant change in the adjusted means of the BDI-II and BECK scores between the zinc vs. placebo groups. Twelve weeks of Zn supplementation was able to partially improve the cognitive scores assessed in overweight or obese women, regardless of weight loss. These findings suggest that Zn supplementation can be considered an adjunct strategy to enhance cognitive health in overweight or obese women.

Genes Involved by Dexamethasone in Prevention of Long-Term Memory Impairment Caused by Lipopolysaccharide-Induced Neuroinflammation

Inflammatory activation within the brain is linked to a decrease in cognitive abilities; however, the molecular mechanisms implicated in the development of inflammatory-related cognitive dysfunction and its prevention are poorly understood. This study compared the responses of hippocampal transcriptomes 3 months after the striatal infusion of lipopolysaccharide (LPS; 30 µg), resulting in memory loss, or with dexamethasone (DEX; 5 mg/kg intraperitoneal) pretreatment, which abolished the long-term LPS-induced memory impairment. After LPS treatment, a significant elevation in the expression of immunity/inflammatory-linked genes, including chemokines (Cxcl13), cytokines (Il1b and Tnfsf13b), and major histocompatibility complex (MHC) class II members (Cd74, RT1-Ba, RT1-Bb, RT1-Da, and RT1-Db1) was observed. DEX pretreatment did not change the expression of these genes, but significantly affected the expression of genes encoding ion channels, primarily calcium and potassium channels, regulators of glutamate (Slc1a2, Grm5, Grin2a), and GABA (Gabrr2, Gabrb2) neurotransmission, which enriched in such GO biological processes as "Regulation of transmembrane transport", "Cognition", "Learning", "Neurogenesis", and "Nervous system development". Taken together, these data suggest that (1) pretreatment with DEX did not markedly affect LPS-induced prolonged inflammatory response; (2) DEX pretreatment can affect processes associated with glutamatergic signaling and nervous system development, possibly involved in the recovery of memory impairment induced by LPS.

Can Genetic Markers Predict the Sporadic Form of Alzheimer's Disease? An Updated Review on Genetic Peripheral Markers

Alzheimer's disease (AD) is the most common form of dementia that affects millions of individuals worldwide. Although the research over the last decades has provided new insight into AD pathophysiology, there is currently no cure for the disease. AD is often only diagnosed once the symptoms have become prominent, particularly in the late-onset (sporadic) form of AD. Consequently, it is essential to further new avenues for early diagnosis. With recent advances in genomic analysis and a lower cost of use, the exploration of genetic markers alongside RNA molecules can offer a key avenue for early diagnosis. We have here provided a brief overview of potential genetic markers differentially expressed in peripheral tissues in AD cases compared to controls, as well as considering the changes to the dynamics of RNA molecules. By integrating both genotype and RNA changes reported in AD, biomarker profiling can be key for developing reliable AD diagnostic tools.

Anti-oxidative-initiated cognitive impairment amelioration in Alzheimer's Disease model rats through preventive transcutaneous electrical acupoint stimulation

Background

Alzheimer's disease (AD) is a chronic and irreversible neurodegenerative disease. Oxidative stress emerges at the early AD stage. As a non-invasive therapy with few adverse reactions, transcutaneous electrical acupoint stimulation (TEAS) combines acupuncture points of traditional Chinese medicine (TCM) and electrical stimulation. This study aimed to investigate the amelioration effects of preventive TEAS treatment (P-TEAS) on cognitive impairment and oxidative stress in AD model rats.

Methods

The AD model was established via subcutaneous injections of D-galactose (D-gal, 120 mg/kg/d) into the back of neck for 9 weeks in Sprague Dawley (SD) rats to simulate the oxidative stress in the early AD stage. On the first day of the 10th week, Aβ_1-42 (1 μg/μl) was injected into the CA1 regions of the bilateral hippocampus. P-TEAS was synchronized from the first day of subcutaneous D-gal injections for 9 weeks.

Results

Empirical measurements showed that P-TEAS can improve the spatial memory ability of AD model rats in the Morris water maze. Superoxide dismutase (SOD) was upregulated in the P-TEAS group. Through the detection of the anti-oxidative stress signaling pathway, namely, Kelch-like ECH-associated protein 1 (Keap1)/ NFE2-related factor 2 (Nrf2), it was found that P-TEAS could promote Nrf2 entering into the nucleus and upregulating the production of protective factors heme oxygenase 1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1). It was also found that P-TEAS could downregulate the expressions of BCL2-associated X-protein (Bax), caspase 3, and caspase 9 to inhibit neuronal apoptosis.

Conclusions

P-TEAS has similar efficacy to electroacupuncture in preventing AD occurrence and development. P-TEAS is a new non-invasive intervention therapy for the prevention of AD.