Alzheimer's disease and inflammatory biomarkers positively correlate in plasma in the UK-ADRC cohort

Harnessing human iPSC-microglia for CNS-wide delivery of disease-modifying proteins

Widespread delivery of therapeutic proteins to the brain remains challenging. To determine whether human induced pluripotent stem cell (iPSC)-microglia (iMG) could enable brain-wide and pathology-responsive delivery of therapeutic cargo, we utilized CRISPR gene editing to engineer iMG to express the Aβ-degrading enzyme neprilysin under control of the plaque-responsive promoter, CD9. To further determine whether increased engraftment enhances efficacy, we utilized a CSF1R-inhibitor resistance approach. Interestingly, both localized and brain-wide engraftment in Alzheimer's disease (AD) mice reduced multiple biochemical measures of pathology. However, within the plaque-dense subiculum, reductions in plaque load, dystrophic neurites, and astrogliosis and preservation of neuronal density were only achieved following widespread microglial engraftment. Lastly, we examined chimeric models of breast cancer brain metastases and demyelination, demonstrating that iMG adopt diverse transcriptional responses to differing neuropathologies, which could be harnessed to enable widespread and pathology-responsive delivery of therapeutics to the CNS.

Elevated cerebrospinal fluid biomarkers of neuroinflammation and neuronal damage in essential hypertension with secondary insomnia: Implications for Alzheimer's disease risk

Essential hypertension (EH) with secondary insomnia is associated with increased risks of neuroinflammation, neuronal damage, and Alzheimer's disease (AD). However, its relationship with specific cerebrospinal fluid (CSF) biomarkers of neuronal damage and neuroinflammation remains unclear. This case-control study compared CSF biomarker levels across three groups: healthy controls (HC, n = 64), hypertension-controlled (HTN-C, n = 54), and hypertension-uncontrolled (HTN-U, n = 107) groups, all EH participants experiencing secondary insomnia. CSF samples from knee replacement patients were analyzed for key biomarkers, and sleep quality was assessed via the Pittsburgh Sleep Quality Index (PSQI). Our findings showed that the HTN-U group had significantly higher CSF levels of proinflammatory cytokines IL-6, TNF-α, and IL-17 than the HC and HTN-C groups (all p < 0.01). These cytokines correlated positively with secondary insomnia measures, with IL-6 (r = 0.285, p = 0.003), IL-17 (r = 0.324, p = 0.001), and TNF-α (r = 0.274, p = 0.005) linked to PSQI scores. In the HTN-U group, elevated IL-6, TNF-α, and IL-17 levels were also positively associated with neurofilament light (NF-L) and negatively with β-amyloid 42 (Aβ42), both key AD markers (all p < 0.05). Additionally, secondary insomnia was negatively correlated with Aβ42 (r = -0.225, p = 0.021) and positively with NF-L (r = 0.261, p = 0.007). Higher CSF palmitic acid (PA) levels observed in the HTN-U group were linked to poorer sleep quality (r = 0.208, p = 0.033). In conclusion, EH with secondary insomnia is associated with CSF biomarkers of neuronal damage, neuroinflammation, and neurodegeneration, suggesting a potential increase in AD risk among this population.

Analysis of inflammatory biomarkers IL-6, vascular endothelial growth factor and matrix metalloproteinases-9 expression in endometriosis

Objective

Special attention has been paid to genetic mechanisms that might have a significant impact on the context of the risk of developing endometriosis, in recent years. The study aimed to analyze the expression levels of three inflammatory biomarkers Interleukin-6 (IL-6), vascular endothelial growth factor, and matrix metalloproteinases-9, in the increased incidence of endometriosis.

Methods

The material for genetic testing was tissue slices embedded in paraffin blocks from these patients with endometriosis (I-II) (n = 24), endometriosis (III-IV) (n = 24), and the control group (n = 30) in Lianyungang maternal and child health hospital from January 2020 to December 2023. The expression levels of IL-6, vascular endothelial growth factor, and matrix metalloproteinases-9 genes were determined by the real-time polymerase chain reaction technique.

Results

The expression levels of IL-6 and vascular endothelial growth factor gene in the peripheral blood and peritoneal fluid of these endometriosis patients were not statistically significant lower than in the control group. Besides, the significant differences were found in IL-6, vascular endothelial growth factor and matrix metalloproteinases-9 between eutopic endometrial tissues of the endometriosis group, compared to the control group; and these increased significantly with the severity of the disease. In addition, there was significant difference in the expression level of matrix metalloproteinases-9 in peripheral blood and peritoneal fluid, and the difference was statistically significant in these patients with stages III-IV, compared with these patients with stages I-II. Among them, the Revised American Society for Reproductive Medicine classification of endometriosis was used in the group of patients with endometriosis.

Conclusion

These patients with endometriosis showed the significant differences in matrix metalloproteinases-9 expression in peripheral blood, peritoneal fluid, and eutopic and ectopic endometrial tissues as the condition worsens. The research suggested that the determination of matrix metalloproteinases-9 in peripheral blood has certain value in evaluating the condition of endometriosis, which might play an important role in the pathogenesis of endometriosis and be explored for postoperative recurrence monitoring.

Role of Flavonoids in Mitigating the Pathological Complexities and Treatment Hurdles in Alzheimer's Disease

With the passage of time, people step toward old age and become more prone to several diseases associated with the age. One such is Alzheimer's disease (AD) which results into neuronal damage and dementia with the progression of age. The existing therapeutics has been hindered by various enkindles like less eminent between remote populations, affordability issues and toxicity profiles. Moreover, lack of suitable therapeutic option further worsens the quality of life in older population. Developing an efficient therapeutic intervention to cure AD is still a challenge for medical fraternity. Recently, alternative approaches attain the attention of researchers to focus on plant-based therapy in mitigating AD. In this context, flavonoids gained centrality as a feasible treatment in modifying various neurological deficits. This review mainly focuses on the pathological facets and economic burden of AD. Furthermore, we have explored the possible mechanism of flavonoids with the preclinical and clinical aspects for curing AD. Flavonoids being potential therapeutic, target the pathogenic factors of AD such as oxidative stress, inflammation, metal toxicity, Aβ accumulation, modulate neurotransmission and insulin signaling. In this review, we emphasized on potential neuroprotective effects of flavonoids in AD pathology, with focus on both experimental and clinical findings. While preclinical studies suggest promising therapeutic benefits, clinical data remains limited and inconclusive. Thus, further high-quality clinical trials are necessary to validate the efficacy of flavonoids in AD. The study aim is to promote the plant-based therapies and encourage people to add flavonoids to regular diet to avail the beneficial effects in preventive therapy for AD.

Biological brain age and resilience in cognitively unimpaired 70-year-old individuals

INTRODUCTION

This study investigated the associations of brain age gap (BAG)-a biological marker of brain resilience-with life exposures, neuroimaging measures, biological processes, and cognitive function.

METHODS

We derived BAG by subtracting predicted brain age from chronological age in 739 septuagenarians without dementia or neurological disorders. Robust linear regression models assessed BAG associations with life exposures, plasma inflammatory and metabolic biomarkers, magnetic resonance imaging, and cerebrospinal fluid biomarkers of neurodegeneration and vascular brain injury, and cognitive performance.

RESULTS

Greater BAG (older-looking brains) was associated with physical inactivity, diabetes, and stroke, while prediabetes was related to lower BAG, that is, younger-looking brains. Physical activity mitigated the link between obesity and BAG. Greater BAG was associated with greater small vessel disease burden, white-matter alterations, inflammation, high glucose, poorer vascular-related cognitive domains. Sex-specific associations were identified.

DISCUSSION

Vascular-related lifestyles and health shape brain appearance. Inflammation and insulin-related processes may be keys to understanding vascular cognitive disorders.

HIGHLIGHTS

BAG, reflecting deviations from CA, can indicate resilience. Diabetes, stroke, and low physical activity link to "older" brains (greater BAG). Physical activity yielded to "younger" brains in septuagenarians with obesity. High cerebrovascular burden, inflammation, and glucose associate with "older" brains. Sex differences were detected in all BAG-associated factors.

Recent Insights on the Role of Nuclear Receptors in Alzheimer's Disease: Mechanisms and Therapeutic Application

Nuclear receptors (NRs) are ligand-activated transcription factors that regulate a broad array of biological processes, including inflammation, lipid metabolism, cell proliferation, and apoptosis. Among the diverse family of NRs, peroxisome proliferator-activated receptors (PPARs), estrogen receptor (ER), liver X receptor (LXR), farnesoid X receptor (FXR), retinoid X receptor (RXR), and aryl hydrocarbon receptor (AhR) have garnered significant attention for their roles in neurodegenerative diseases, particularly Alzheimer's disease (AD). NRs influence the pathophysiology of AD through mechanisms such as modulation of amyloid-beta (Aβ) deposition, regulation of inflammatory pathways, and improvement of neuronal function. However, the dual role of NRs in AD progression, where some receptors may exacerbate the disease while others offer therapeutic potential, presents a critical challenge for their application in AD treatment. This review explores the functional diversity of NRs, highlighting their involvement in AD-related processes and discussing the therapeutic prospects of NR-targeting strategies. Furthermore, the key challenges, including the necessity for the precise identification of beneficial NRs, detailed structural analysis through molecular dynamics simulations, and further investigation of NR mechanisms in AD, such as tau pathology and autophagy, are also discussed. Collectively, continued research is essential to clarify the role of NRs in AD, ultimately facilitating their potential use in the diagnosis, prevention, and treatment of AD.

Investigating interleukin-8 in Alzheimer's disease: A comprehensive review

Several studies indicate that the development of Alzheimer's disease (AD) has strong interactions with immune mechanisms within the brain, indicating a close association between inflammation in the central nervous system and the progression of neurodegeneration. Despite considerable progress in understanding the inflammatory aspects of AD, several of them remain unresolved. Pro-inflammatory cytokines and microglia are pivotal components in the inflammatory cascade. Among these, the role of interleukin-8 (IL-8) in neurodegeneration seems complex and multifaceted, involving inflammation, neurotoxicity, blood-brain barrier disruption, and oxidative stress, and is still poorly characterized. We conducted a review to describe the evidence of IL-8 involvement in AD. IL-8 is a cytokine known for its proinflammatory properties and typically produced by macrophages, predominantly functions as a chemotactic signal for attracting neutrophils to inflamed sites in the bloodstream. Interestingly, IL-8 is also present in the brain, where it is primarily released by microglia in response to inflammatory signals. This review aims to provide a comprehensive overview of the structure, function, and regulatory mechanisms of IL-8 relevant to AD pathology.

Palmitoyl-L-carnitine induces tau phosphorylation and mitochondrial dysfunction in neuronal cells

Alzheimer's disease (AD) is characterized by cognitive decline and memory loss, involving mechanisms such as tau hyperphosphorylation and mitochondrial dysfunction. Increasing evidence suggests that age-related alterations in metabolite levels are crucial for the pathogenesis of AD. Here, we analyzed serum metabolites from mice of various ages (2, 4, 14, and 21 months old) using mass spectrometry. We identified palmitoyl-L-carnitine as a key metabolite with significantly increased levels in aged mice. In vitro experiments with SH-SY5Y neuronal cells demonstrated that palmitoyl-L-carnitine treatment enhanced tau phosphorylation, increased mitochondrial fission, and elevated intracellular calcium levels. Furthermore, the increased levels of tau phosphorylation were significantly reduced by the inhibition of GSK-3β, CDK5, and calpain, indicating that tau kinases activated by calcium overload are directly involved in the increase of tau phosphorylation. Considering that mitochondrial fission is related to mitochondrial dysfunction, we propose that the elevated level of serum palmitoyl-L-carnitine during aging contributes to AD pathology through these pathways. These findings highlight the significant role of lipid metabolism in neurodegeneration and offer potential therapeutic targets for age-related diseases, including AD.

Elevated C-Reactive Protein in Older Men With Chronic Pain: Association With Plasma Amyloid Levels and Hippocampal Volume

BACKGROUND

Chronic pain leads to tau accumulation and hippocampal atrophy, which may be moderated through inflammation. In older men, we examined associations of chronic pain with Alzheimer's disease (AD)-related plasma biomarkers and hippocampal volume as moderated by systemic inflammation.

METHODS

Participants were men without dementia. Chronic pain was defined as moderate-to-severe pain in 2+ study waves at average ages 56, 62, and 68. At age 68, we measured plasma amyloid-beta (Aβ42, n = 871), Aβ40 (n = 887), total tau (t-tau, n = 841), and neurofilament light chain (NfL, n = 915), and serum high-sensitivity C-reactive protein (hs-CRP, n = 968), a marker of systemic inflammation. A subgroup underwent structural MRI to measure hippocampal volume (n = 385). Analyses adjusted for medical morbidities, depressive symptoms, and opioid use.

RESULTS

Chronic pain was related to higher Aβ40 (β = 0.25, p = .009), but hs-CRP was unrelated to AD-related biomarkers (ps > .05). There was a significant interaction such that older men with both chronic pain and higher levels of hs-CRP had higher levels of Aβ42 (β = 0.36, p = .001) and Aβ40 (β = 0.29, p = .003). Chronic pain and hs-CRP did not interact to predict levels of Aβ42/Aβ40, t-tau, or NfL. Furthermore, there were significant interactions such that Aβ42 and Aβ40 were associated with lower hippocampal volume, particularly when levels of hs-CRP were elevated (hs-CRP × Aβ42: β = -0.19, p = .002; hs-CRP × Aβ40: β = -0.21, p = .001), regardless of chronic pain status.

CONCLUSIONS

Chronic pain was associated with higher plasma Aβ, especially when hs-CRP was also elevated. Higher hs-CRP and Aβ levels were both related to smaller hippocampal volumes. Chronic pain, when accompanied by systemic inflammation, may elevate the risk of neurodegeneration in AD-vulnerable regions.

CSF and blood glial fibrillary acidic protein for the diagnosis of Alzheimer's disease: A systematic review and meta-analysis

Recently included in the 2024 new revised diagnostic criteria of Alzheimer's disease (AD), glial fibrillary acidic protein (GFAP) has garnered significant attention. A systematic review and meta-analysis were performed to comprehensively evaluate the diagnostic, differential diagnostic, and prospective diagnostic performance of GFAP in cerebrospinal fluid (CSF) and blood for AD continuum. A literature search using common electronic databases, important websites and historical search way was performed from inception to the beginning of March 2023. The inclusion criteria was studies evaluating the diagnostic accuracy of GFAP in CSF and/or blood for the AD continuum patients, utilizing PET scans, CSF biomarkers and/or clinical criteria. The systematic review and meta-analysis were conducted referring to the Cochrane Handbook. In total, 34 articles were eventually included in the meta-analysis, 29 of which were published within the past three years. Blood GFAP exhibited good diagnostic accuracy across various AD continuum patients, and the summary area under curve for distinguishing PET positive and negative individuals, CSF biomarkers defined positive and negative individuals, clinically diagnosed AD and cognitive unimpaired controls, AD and/or mild cognitive impairment and other neurological diseases, and prospective cases and controls was 0.85[0.81-0.88], 0.77[0.73-0.81], 0.92[0.90-0.94], 0.80[0.77-0.84], and 0.79[0.75-0.82], respectively. Only several studies were recognized to evaluate the diagnostic accuracy of CSF GFAP, which was not as good as that of blood GFAP (paired mixed data: AUC = 0.86 vs. AUC = 0.77), but its accuracy remarkably increased to AUC = 0.91 when combined with other factors like sex, age, and ApoE genotype. In summary, GFAP, particularly in blood, shown good diagnostic, differential diagnostic, and prospective diagnostic accuracy for AD continuum patients, with improved accuracy when used alongside other basic indexes.

The Inflammasome Adaptor Protein ASC in Plasma as a Biomarker of Early Cognitive Changes

Dementia is a group of symptoms including memory loss, language difficulties, and other types of cognitive and functional impairments that affects 57 million people worldwide, with the incidence expected to double by 2040. Therefore, there is an unmet need to develop reliable biomarkers to diagnose early brain impairments so that emerging interventions can be applied before brain degeneration. Here, we performed biomarker analyses for apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and amyloid-β 42/40 (Aβ42/40) ratio in the plasma of older adults. Participants had blood drawn at baseline and underwent two annual clinical and cognitive evaluations. The groups tested either cognitively normal on both evaluations (NN), cognitively normal year 1 but cognitively impaired year 2 (NI), or cognitively impaired on both evaluations (II). ASC was elevated in the plasma of the NI group compared to the NN and II groups. Additionally, Aβ42 was increased in the plasma in the NI and II groups compared to the NN group. Importantly, the area under the curve (AUC) for ASC in participants older than 70 years old in NN vs. NI groups was 0.81, indicating that ASC is a promising plasma biomarker for early detection of cognitive decline.

Electrochemical Biosensor for Point-of-Care Testing of Low-Abundance Biomarkers of Neurological Diseases

The neurofilament protein light chain (NEFL) is a potential biomarker of neurodegenerative diseases, and interleukin-6 (IL-6) is also closely related to neuroinflammation. Especially, NEFL and IL-6 are the two most low-abundance known protein markers of neurological diseases, making their detection very important for the early diagnosis and prognosis prediction of such kinds of diseases. Nevertheless, quantitative detection of low concentrations of NEFL and IL-6 in serum remains quite difficult, especially in the point-of-care test (POCT). Herein, we developed a portable, sensitive electrochemical biosensor combined with smartphones that can be applied to multiple scenarios for the quantitative detection of NEFL and IL-6, meeting the need of the POCT. We used a double-antibody sandwich configuration combined with polyenzyme-catalyzed signal amplification to improve the sensitivity of the biosensor for the detection of NEFL and IL-6 in sera. We could detect NEFL as low as 5.22 pg/mL and IL-6 as low as 3.69 pg/mL of 6 μL of serum within 2 h, demonstrating that this electrochemical biosensor worked well with serum systems. Results also showed its superior detection capabilities over those of high-sensitivity ELISA for serum samples. Importantly, by detecting NEFL and IL-6 in sera, the biosensor showed its potential for the POCT model detection of all known biomarkers of neurological diseases, making it possible for the mass screening of patients with neurodegenerative diseases.

Reduction in Hippocampal Amyloid-β Peptide (Aβ) Content during Glycine-Proline-Glutamate (Gly-Pro-Glu) Co-Administration Is Associated with Changes in Inflammation and Insulin-like Growth Factor (IGF)-I Signaling

Alzheimer's disease (AD) is characterized by the deposition in the brain of senile plaques composed of amyloid-β peptides (Aβs) that increase inflammation. An endogenous peptide derived from the insulin-like growth factor (IGF)-I, glycine-proline-glutamate (GPE), has IGF-I-sensitizing and neuroprotective actions. Here, we examined the effects of GPE on Aβ levels and hippocampal inflammation generated by the intracerebroventricular infusion of Aβ25-35 for 2 weeks (300 pmol/day) in ovariectomized rats and the signaling-related pathways and levels of Aβ-degrading enzymes associated with these GPE-related effects. GPE prevented the Aβ-induced increase in the phosphorylation of p38 mitogen-activated protein kinase and the reduction in activation of signal transducer and activator of transcription 3, insulin receptor substrate-1, and Akt, as well as on interleukin (IL)-2 and IL-13 levels in the hippocampus. The functionality of somatostatin, measured as the percentage of inhibition of adenylate cyclase activity and the levels of insulin-degrading enzyme, was also preserved by GPE co-treatment. These findings indicate that GPE co-administration may protect from Aβ insult by changing hippocampal cytokine content and somatostatin functionality through regulation of leptin- and IGF-I-signaling pathways that could influence the reduction in Aβ levels through modulation of levels and/or activity of Aβ proteases.

Circulating biomarkers of inflammaging and Alzheimer's disease to track age-related trajectories of dementia: Can we develop a clinically relevant composite combination?

Alzheimer's disease (AD) is a rapidly growing global concern due to a consistent rise of the prevalence of dementia which is mainly caused by the aging population worldwide. An early diagnosis of AD remains important as interventions are plausibly more effective when started at the earliest stages. Recent developments in clinical research have focused on the use of blood-based biomarkers for improve diagnosis/prognosis of neurodegenerative diseases, particularly AD. Unlike invasive cerebrospinal fluid tests, circulating biomarkers are less invasive and will become increasingly cheaper and simple to use in larger number of patients with mild symptoms or at risk of dementia. In addition to AD-specific markers, there is growing interest in biomarkers of inflammaging/neuro-inflammaging, an age-related chronic low-grade inflammatory condition increasingly recognized as one of the main risk factor for almost all age-related diseases, including AD. Several inflammatory markers have been associated with cognitive performance and AD development and progression. The presence of senescent cells, a key driver of inflammaging, has also been linked to AD pathogenesis, and senolytic therapy is emerging as a potential treatment strategy. Here, we describe blood-based biomarkers clinically relevant for AD diagnosis/prognosis and biomarkers of inflammaging associated with AD. Through a systematic review approach, we propose that a combination of circulating neurodegeneration and inflammatory biomarkers may contribute to improving early diagnosis and prognosis, as well as providing valuable insights into the trajectory of cognitive decline and dementia in the aging population.

Comparative efficacy, tolerability and acceptability of donanemab, lecanemab, aducanumab and lithium on cognitive function in mild cognitive impairment and Alzheimer's disease: A systematic review and network meta-analysis

BACKGROUND

The comparative clinical utility of the disease-modifying treatments for mild cognitive impairment and Alzheimer's disease that are approved or under review by the Food and Drug Administration (i.e., donanemab, lecanemab and aducanumab), and lithium, which is a potential disease-modifying agent for this condition, remains elusive.

OBJECTIVE

We aimed to compare the efficacy on cognitive decline, tolerability and acceptability of these drugs in this condition.

METHODS

We systematically searched in MEDLINE, CENTRAL, CINHAL and ClinicalTrials,gov for randomized controlled trials from their inception to 7 November 2023, and then performed a random-effect network meta-analysis.

RESULTS

The analysis included 8 randomized placebo-controlled trials with 6547 participants. On the Mini-Mental State Examination, lithium significantly outperformed donanemab, aducanumab and placebo. On the Alzheimer's Disease Assessment Scale-cognitive subscale, the efficacy of all active drugs was significantly higher than placebo. In addition, in the Clinical Dementia Rating sum of boxes, the efficacy of donanemab and lecanemab was significantly higher than placebo. Compared to placebo, donanemab and lecanemab were significantly less acceptable and tolerable. Aducanumab was also less well tolerated compared to placebo. There were no significant differences in the other comparisons.

CONCLUSION

Although it is yet to be determined which is more effective between lithium or lecanemab or donanemab, lithium may be more effective than aducanumab. Aducanumab, lecanemab and donanemab do not appear to differ in their effectiveness on cognitive function. Low-dose lithium may be safer than aducanumab, lecanemab and donanemab.

Identification of Blood Biomarkers Related to Energy Metabolism and Construction of Diagnostic Prediction Model Based on Three Independent Alzheimer's Disease Cohorts

Background

Blood biomarkers are crucial for the diagnosis and therapy of Alzheimer's disease (AD). Energy metabolism disturbances are closely related to AD. However, research on blood biomarkers related to energy metabolism is still insufficient.

Objective

This study aims to explore the diagnostic and therapeutic significance of energy metabolism-related genes in AD.

Methods

AD cohorts were obtained from GEO database and single center. Machine learning algorithms were used to identify key genes. GSEA was used for functional analysis. Six algorithms were utilized to establish and evaluate diagnostic models. Key gene-related drugs were screened through network pharmacology.

Results

We identified 4 energy metabolism genes, NDUFA1, MECOM, RPL26, and RPS27. These genes have been confirmed to be closely related to multiple energy metabolic pathways and different types of T cell immune infiltration. Additionally, the transcription factors INSM2 and 4 lncRNAs were involved in regulating 4 genes. Further analysis showed that all biomarkers were downregulated in the AD cohorts and not affected by aging and gender. More importantly, we constructed a diagnostic prediction model of 4 biomarkers, which has been validated by various algorithms for its diagnostic performance. Furthermore, we found that valproic acid mainly interacted with these biomarkers through hydrogen bonding, salt bonding, and hydrophobic interaction.

Conclusions

We constructed a predictive model based on 4 energy metabolism genes, which may be helpful for the diagnosis of AD. The 4 validated genes could serve as promising blood biomarkers for AD. Their interaction with valproic acid may play a crucial role in the therapy of AD.