Predictive Value of Routine Peripheral Blood Biomarkers in Alzheimer's Disease

Neuroinflammation in Alzheimer's disease: insights from peripheral immune cells

Alzheimer's disease (AD) is a serious brain disorder characterized by the presence of beta-amyloid plaques, tau pathology, inflammation, neurodegeneration, and cerebrovascular dysfunction. The presence of chronic neuroinflammation, breaches in the blood-brain barrier (BBB), and increased levels of inflammatory mediators are central to the pathogenesis of AD. These factors promote the penetration of immune cells into the brain, potentially exacerbating clinical symptoms and neuronal death in AD patients. While microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in AD, recent evidence suggests the infiltration of cerebral vessels and parenchyma by peripheral immune cells, including neutrophils, T lymphocytes, B lymphocytes, NK cells, and monocytes in AD. These cells participate in the regulation of immunity and inflammation, which is expected to play a huge role in future immunotherapy. Given the crucial role of peripheral immune cells in AD, this article seeks to offer a comprehensive overview of their contributions to neuroinflammation in the disease. Understanding the role of these cells in the neuroinflammatory response is vital for developing new diagnostic markers and therapeutic targets to enhance the diagnosis and treatment of AD patients.

Correlation analysis of peripheral platelet markers and disease phenotypes in Alzheimer's disease

INTRODUCTION

Platelets serve as the primary peripheral reservoir of amyloid beta (Aβ). However, there is limited research on platelet markers in routine blood examinations, particularly with regard to the large platelet ratio (P-LCR) in Alzheimer's disease (AD).

METHODS

This study included 512 AD patients and 205 healthy controls (HCs). Platelet markers and apolipoprotein E (APOE) 4 status were assessed in all participants.

RESULTS

The study revealed that P-LCR was significantly elevated in AD patients compared to HCs. In AD patients carrying APOE4, P-LCR significantly negatively correlated with Montreal Cognitive Assessment scores. There was an observed increasing trend in the rate of change in P-LCR with disease progression. Binary logistic regression analysis indicated that P-LCR may constitute a risk factor for AD, after adjusting for age, sex, APOE4, and body mass index.

DISCUSSION

P-LCR is associated with disease severity in AD patients carrying APOE4. P-LCR may be a promising marker to reflect platelet activity in AD patients.

HIGHLIGHTS

P-LCR significantly negatively correlated with MoCA scores in AD patients with APOE4. The rate of change in P-LCR showed an increasing trend with disease progression. P-LCR may be a risk factor for AD.

The relationship between intraoperative hypothermia and postoperative delirium: The PNDRFAP study

OBJECTIVE

Our study aimed to investigate the correlation between intraoperative hypothermia and postoperative delirium (POD) in patients undergoing general anesthesia for gastrointestinal surgery.

METHODS

The study comprised 750 participants from the Perioperative Neurocognitive Disorder Risk Factor and Prognosis (PNDRFAP) study database, which ultimately screened 510 individuals in the final analysis. Preoperative cognitive function was evaluated using the Mini-Mental State Examination (MMSE). The occurrence of POD was determined using the Confusion Assessment Method, and the severity of POD was evaluated using the Memorial Delirium Assessment Scale. Logistic regression was employed to scrutinize the association between intraoperative hypothermia and the incidence of POD, and the sensitivity analysis was conducted by introducing adjusted confounding variables. Decision curves and a nomogram model were utilized to assess the predictive efficacy of intraoperative hypothermia for POD. Mediation analysis involving 10,000 bootstrapped iterations was employed to appraise the suggested mediating effect of numeric rating scale (NRS) scores at 24 and 48 h post-surgeries. The receiver-operating characteristic (ROC) was utilized to evaluate the effectiveness of intraoperative hypothermia in predicting POD.

RESULTS

In the PNDRFAP study, the occurrence of POD was notably higher in the intraoperative hypothermia group (62.2%) compared to the intraoperative normal body temperature group (9.8%), with an overall POD incidence of 17.6%. Logistic regression analysis, adjusted for various confounding factors (age [40-90], gender, education, MMSE, smoking history, drinking history, hypertension, diabetes, and the presence of cardiovascular heart disease), demonstrated that intraoperative hypothermia significantly increased the risk of POD (OR = 4.879, 95% CI = 3.020-7.882, p < .001). Mediation analyses revealed that the relationship between intraoperative hypothermia and POD was partially mediated by NRS 24 h after surgery, accounting for 14.09% of the association (p = .002). The area under the curve of the ROC curve was 0.685, which confirmed that intraoperative hypothermia could predict POD occurrence to a certain extent. Decision curve and nomogram analyses, conducted using the R package, further substantiated the predictive efficacy of intraoperative hypothermia on POD.

CONCLUSION

Intraoperative hypothermia may increase the risk of POD, and this association may be partially mediated by NRS scores 24 h after surgery.

Systemic inflammation in relation to exceptional memory in the Long Life Family Study (LLFS)

Background and objectives

We previously found a substantial familial aggregation of healthy aging phenotypes, including exceptional memory (EM) in long-lived persons. In the current study, we aim to assess whether long-lived families with EM and without EM (non-EM) differ in systemic inflammation status and trajectory.

Methods

The current study included 4333 participants of the multi-center Long Life Family Study (LLFS). LLFS families were classified as EM (556 individuals from 28 families) or non-EM (3777 individuals from 416 families), with 2 or more offspring exhibiting exceptional memory performance (i.e. having baseline composite z-score representing immediate and delayed story memory being 1.5 SD above the mean in the nondemented offspring sample) considered as EM. Blood samples from baseline were used to measure inflammatory biomarkers including total white blood cell (WBC) and its subtypes (neutrophils, lymphocytes, monocytes) count, platelet count, high sensitivity C-reactive protein, and interleukin-6. Generalized linear models were used to examine cross-sectional differences in inflammatory biomarkers at baseline. In a sub-sample of 2227 participants (338 subjects from 24 EM families and 1889 from 328 non-EM families) with repeated measures of immune cell counts, we examined whether the rate of biomarker change differed between EM and non-EM families. All models were adjusted for family size, relatedness, age, sex, education, field center, APOE genotype, and body mass index.

Results

LLFS participants from EM families had a marginally higher monocyte count at baseline (b = 0.028, SE = 0.0110, p = 0.010) after adjusting for age, sex, education, and field site, particularly in men (p < 0.0001) but not in women (p = 0.493) (p-interaction = 0.003). Over time, monocyte counts increased (p < 0.0001) in both EM and non-EM families, while lymphocytes and platelet counts decreased over time in the non-EM families (p < 0.0001) but not in the EM families. After adjusting for multiple variables, there was no significant difference in biomarker change over time between the EM and non-EM families.

Discussion

Compared with non-EM families, EM families had significantly higher monocyte count at baseline but had similar change over time. Our study suggests that differences in monocyte counts may be a pathway through which EM emerges in some long-lived families, especially among men.

The characteristic and prognostic role of blood inflammatory markers in patients with Huntington's disease from China

Objectives

This study aims to elucidate the role of peripheral inflammation in Huntington's disease (HD) by examining the correlation of peripheral inflammatory markers with clinical manifestations and disease prognosis.

Methods

This investigation involved 92 HD patients and 92 matched healthy controls (HCs). We quantified various peripheral inflammatory markers and calculated their derived metrics including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and systemic immune-inflammation index (SII). Clinical assessments spanning cognitive, motor, and disease severity were administered. Comparative analysis of inflammatory markers and clinical correlations between HD and controls was performed. Kaplan-Meier survival analysis and Cox regression model were used to assess the effect of inflammatory markers on survival.

Results

The study revealed that HD patients had significantly reduced lymphocyte counts, and LMR. Conversely, NLR, PLR, and SII were elevated compared to HCs. Lymphocyte levels inversely correlated with the age of onset and monocyte levels inversely correlated with the UHDRS-total functional capacity (TFC) scores. After adjusting for age, sex, and CAG repeat length, lymphocyte count, NLR, PLR, and SII were significantly correlated with the progression rate of TFC scores. Elevated levels of white blood cells and monocytes were associated with an increased risk of disability and mortality in the HD cohort.

Conclusion

Our findings indicate that HD patients display a distinct peripheral inflammatory profile with increased NLR, PLR, and SII levels compared to HCs. The peripheral inflammation appears to be linked with accelerated disease progression and decreased survival in HD.

Development and validation of a diagnostic model to differentiate spinal tuberculosis from pyogenic spondylitis by combining multiple machine learning algorithms

This study focused on the development and validation of a diagnostic model to differentiate between spinal tuberculosis (STB) and pyogenic spondylitis (PS). We analyzed a total of 387 confirmed cases, out of which 241 were diagnosed with STB and 146 were diagnosed with PS. These cases were randomly divided into a training group (n = 271) and a validation group (n = 116). Within the training group, four machine learning (ML) algorithms (least absolute shrinkage and selection operator [LASSO], logistic regression analysis, random forest, and support vector machine recursive feature elimination [SVM-RFE]) were employed to identify distinctive variables. These specific variables were then utilized to construct a diagnostic model. The model's performance was subsequently assessed using the receiver operating characteristic (ROC) curves and the calibration curves. Finally, internal validation of the model was undertaken in the validation group. Our findings indicate that PS patients had an average platelet-to-neutrophil ratio (PNR) of 277.86, which was significantly higher than the STB patients' average of 69.88. The average age of PS patients was 54.71 years, older than the 48 years recorded for STB patients. Notably, the neutrophil-to-lymphocyte ratio (NLR) was higher in PS patients at 6.15, compared to the 3.46 NLR in STB patients. Additionally, the platelet volume distribution width (PDW) in PS patients was 0.2, compared to 0.15 in STB patients. Conversely, the mean platelet volume (MPV) was lower in PS patients at an average of 4.41, whereas STB patients averaged 8.31. Hemoglobin (HGB) levels were lower in PS patients at an average of 113.31 compared to STB patients' average of 121.64. Furthermore, the average red blood cell (RBC) count was 4.26 in PS patients, which was less than the 4.58 average observed in STB patients. After evaluation, seven key factors were identified using the four ML algorithms, forming the basis of our diagnostic model. The training and validation groups yielded area under the curve (AUC) values of 0.841 and 0.83, respectively. The calibration curves demonstrated a high alignment between the nomogram-predicted values and the actual measurements. The decision curve indicated optimal model performance with a threshold set between 2% and 88%. In conclusion, our model offers healthcare practitioners a reliable tool to efficiently and precisely differentiate between STB and PS, thereby facilitating swift and accurate diagnoses.

Association between mean platelet volume and obstructive sleep apnea-hypopnea syndrome: A systemic review and meta-analysis

BACKGROUND

Despite polysomnography (PSG) being acknowledged being considered the gold standard for diagnosing obstructive sleep apnea-hypopnea syndrome (OSAHS), researchers have been seeking a biomarker that is less invasive, more practical in detection, and cost-effective for diagnosing and assessing the severity of the disease. To address this concern, the values of mean platelet volume (MPV) between patients with OSAHS and healthy controls were compared, and the relationship between MPV and multiple sleep monitoring parameters was analyzed in this study.

METHODS

A comprehensive search was conducted across medical databases, including PubMed, Web of Science, EMBASE, CNKI, and Wanfang, up until August 2, 2023, to identify published articles related to OSAHS. This study reviewed the literature regarding the values of MPV in individuals with OSAHS and control groups, the Pearson/Spearman correlation coefficients between MPV and sleep monitoring parameters, and the odds ratios (OR) of MPV concerning the occurrence of cardiovascular diseases (CVDs) in patients with OSAHS. Meta-analyses were performed using standardized mean difference (SMD), Fisher's z values correlation coefficients (ZCOR) and odds ratio (OR) as effect variables. A fixed-effect model was used if the heterogeneity was not significant (I2<50%); otherwise, a random-effect model was applied. We will also combine the treatment effect estimates of individual trials using fixed-effect and random-effects models. Statistical analysis was carried out by employing STATA 11.0 and R 4.1.3.

RESULTS

In total, 31 articles were selected for the final analysis. The study involved 3604 patients and 1165 control individuals. The MPV in the OSAHS group was considerably elevated in comparison to the healthy controls (SMD = 0.37, 95%CI = 0.21-0.53, P < 0.001), particularly among individuals with severe OSAHS (SMD = 0.57, 95%CI = 0.23-0.90, P = 0.001). Subgroup analysis based on ethnicity, mean body mass index (BMI), and study design type also revealed a considerably higher MPV in the OSAHS category in comparison to the healthy controls. Furthermore, MPV showed correlations with various sleep monitoring parameters. The elevation of MPV may be one of the risk factors for CVDs in individuals with OSAHS (adjusted OR = 1.72, 95%CI = 1.08-2.73, P = 0.022).

CONCLUSION

MPV is a relatively simple, cost-effective, and practical indicator of the severity of OSAHS, with its values being linked to the risk of CVDs in individuals with OSAHS.

Peripheral blood amyloid-β involved in the pathogenesis of Alzheimer's disease via impacting on peripheral innate immune cells

A key pathological factor of Alzheimer's disease (AD), the most prevalent form of age-related dementia in the world, is excessive β-amyloid protein (Aβ) in extracellular aggregation in the brain. And in the peripheral blood, a large amount of Aβ is derived from platelets. So far, the causality between the levels of peripheral blood Aβ and its aggregation in the brain, particularly the role of the peripheral blood Aβ in the pathology of AD, is still unclear. And the relation between the peripheral blood Aβ and tau tangles of brain, another crucial pathologic factor contributing to the pathogenesis of AD, is also ambiguous. More recently, the anti-Aβ monoclonal antibodies are approved for treatment of AD patients through declining the peripheral blood Aβ mechanism of action to enhance plasma and central nervous system (CNS) Aβ clearance, leading to a decrease Aβ burden in brain and improving cognitive function, which clearly indicates that the levels of the peripheral blood Aβ impacted on the Aβ burden in brain and involved in the pathogenesis of AD. In addition, the role of peripheral innate immune cells in AD remains mostly unknown and the results obtained were controversial. In the present review, we summarize recent studies on the roles of peripheral blood Aβ and the peripheral innate immune cells in the pathogenesis of AD. Finally, based on the published data and our own work, we believe that peripheral blood Aβ plays an important role in the development and progression of AD by impacting on the peripheral innate immune cells.

Digital Clock and Recall is superior to the Mini-Mental State Examination for the detection of mild cognitive impairment and mild dementia

BACKGROUND

Disease-modifying treatments for Alzheimer's disease highlight the need for early detection of cognitive decline. However, at present, most primary care providers do not perform routine cognitive testing, in part due to a lack of access to practical cognitive assessments, as well as time and resources to administer and interpret the tests. Brief and sensitive digital cognitive assessments, such as the Digital Clock and Recall (DCR™), have the potential to address this need. Here, we examine the advantages of DCR over the Mini-Mental State Examination (MMSE) in detecting mild cognitive impairment (MCI) and mild dementia.

METHODS

We studied 706 participants from the multisite Bio-Hermes study (age mean ± SD = 71.5 ± 6.7; 58.9% female; years of education mean ± SD = 15.4 ± 2.7; primary language English), classified as cognitively unimpaired (CU; n = 360), mild cognitive impairment (MCI; n = 234), or probable mild Alzheimer's dementia (pAD; n = 111) based on a review of medical history with selected cognitive and imaging tests. We evaluated cognitive classifications (MCI and early dementia) based on the DCR and the MMSE against cohorts based on the results of the Rey Auditory Verbal Learning Test (RAVLT), the Trail Making Test-Part B (TMT-B), and the Functional Activities Questionnaire (FAQ). We also compared the influence of demographic variables such as race (White vs. Non-White), ethnicity (Hispanic vs. Non-Hispanic), and level of education (≥ 15 years vs. < 15 years) on the DCR and MMSE scores.

RESULTS

The DCR was superior on average to the MMSE in classifying mild cognitive impairment and early dementia, AUC = 0.70 for the DCR vs. 0.63 for the MMSE. DCR administration was also significantly faster (completed in less than 3 min regardless of cognitive status and age). Among 104 individuals who were labeled as "cognitively unimpaired" by the MMSE (score ≥ 28) but actually had verbal memory impairment as confirmed by the RAVLT, the DCR identified 84 (80.7%) as impaired. Moreover, the DCR score was significantly less biased by ethnicity than the MMSE, with no significant difference in the DCR score between Hispanic and non-Hispanic individuals.

CONCLUSIONS

DCR outperforms the MMSE in detecting and classifying cognitive impairment-in a fraction of the time-while being not influenced by a patient's ethnicity. The results support the utility of DCR as a sensitive and efficient cognitive assessment in primary care settings.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04733989.

Prediction of poststroke cognitive impairment based on the systemic inflammatory response index

BACKGROUND

Poststroke cognitive impairment (PSCI) is a prevalent complication among stroke survivors. Although the systemic inflammatory response index (SIRI) has been shown to be a reliable predictor of a variety of inflammatory diseases, the association between the SIRI and PSCI is still unclear. Therefore, the purpose of this study was to investigate the relationship between SIRI and PSCI, and to design a nomogram to predict the risk of PSCI in acute ischemic stroke (AIS) patients.

METHODS

A total of 1342 patients with AIS were included in the study. Using the Mini-Mental State Examination scale, patients were separated into PSCI and non-PSCI groups within 2 weeks of stroke. Clinical data and SIRI values were compared between the groups. We developed the optimal nomogram for predicting PSCI using multivariate logistic regression. Finally, the nomogram was validated using the receiver operating characteristic curve, calibration curve, and decision curve analysis (DCA).

RESULTS

In total, 690 (51.4%) patients were diagnosed with PSCI. After adjusting for potential confounders, the SIRI (OR = 1.226, OR: 1.095-1.373, p < .001) was shown to be an independent risk factor for PSCI in the logistic regression analysis. The nomogram based on patient gender, age, admission National Institutes of Health Stroke Scale scores, education, diabetes mellitus, and SIRI had good discriminative ability with an area under the curve (AUC) of 0.716. The calibration curve and Hosmer-Lemeshow test revealed excellent predictive accuracy for the nomogram. Finally, the DCA showed the good clinical utility of the model.

CONCLUSION

Increased SIRI on admission is correlated with PSCI, and the nomogram built with SIRI as one of the predictors can help identify PSCI early.

Alzheimer's disease: The role of T lymphocytes in neuroinflammation and neurodegeneration

Alzheimer's disease, the leading cause of progressive cognitive decline globally, has been reported to be enhanced by neuroinflammation. Brain-resident innate immune cells and adaptive immune cells work together to produce neuroinflammation. Studies over the past decade have established the neuroimmune axis present in Alzheimer's disease; the crosstalk between adaptive and innate immune cells within and outside the brain is crucial to the onset and progression of Alzheimer's disease. Although the role of the adaptive immune system in Alzheimer's disease is not fully understood, it has been hypothesized that the brain's immune homeostasis is significantly disrupted, which greatly contributes to neuroinflammation. Brain-infiltrating T cells possess proinflammatory phenotypes and activities that directly contribute to neuroinflammation. The pro-inflammatory activities of the adaptive immune system in Alzheimer's disease are characterized by the upregulation of effector T cell activities and the downregulation of regulatory T cell activities in the brain, blood, and cerebrospinal fluid. In this review, we discuss the major impact of T lymphocytes on the pathogenesis and progression of Alzheimer's disease. Understanding the role and mechanism of action of T cells in Alzheimer's disease would significantly contribute to the identification of novel biomarkers for diagnosing and monitoring the progression of the disease. This knowledge could also be crucial to the development of immunotherapies for Alzheimer's disease.

Machine learning analyses identify multi-modal frailty factors that selectively discriminate four cohorts in the Alzheimer's disease spectrum: a COMPASS-ND study

BACKGROUND

Frailty indicators can operate in dynamic amalgamations of disease conditions, clinical symptoms, biomarkers, medical signals, cognitive characteristics, and even health beliefs and practices. This study is the first to evaluate which, among these multiple frailty-related indicators, are important and differential predictors of clinical cohorts that represent progression along an Alzheimer's disease (AD) spectrum. We applied machine-learning technology to such indicators in order to identify the leading predictors of three AD spectrum cohorts; viz., subjective cognitive impairment (SCI), mild cognitive impairment (MCI), and AD. The common benchmark was a cohort of cognitively unimpaired (CU) older adults.

METHODS

The four cohorts were from the cross-sectional Comprehensive Assessment of Neurodegeneration and Dementia dataset. We used random forest analysis (Python 3.7) to simultaneously test the relative importance of 83 multi-modal frailty indicators in discriminating the cohorts. We performed an explainable artificial intelligence method (Tree Shapley Additive exPlanation values) for deep interpretation of prediction effects.

RESULTS

We observed strong concurrent prediction results, with clusters varying across cohorts. The SCI model demonstrated excellent prediction accuracy (AUC = 0.89). Three leading predictors were poorer quality of life ([QoL]; memory), abnormal lymphocyte count, and abnormal neutrophil count. The MCI model demonstrated a similarly high AUC (0.88). Five leading predictors were poorer QoL (memory, leisure), male sex, abnormal lymphocyte count, and poorer self-rated eyesight. The AD model demonstrated outstanding prediction accuracy (AUC = 0.98). Ten leading predictors were poorer QoL (memory), reduced olfaction, male sex, increased dependence in activities of daily living (n = 6), and poorer visual contrast.

CONCLUSIONS

Both convergent and cohort-specific frailty factors discriminated the AD spectrum cohorts. Convergence was observed as all cohorts were marked by lower quality of life (memory), supporting recent research and clinical attention to subjective experiences of memory aging and their potentially broad ramifications. Diversity was displayed in that, of the 14 leading predictors extracted across models, 11 were selectively sensitive to one cohort. A morbidity intensity trend was indicated by an increasing number and diversity of predictors corresponding to clinical severity, especially in AD. Knowledge of differential deficit predictors across AD clinical cohorts may promote precision interventions.

Relationship between preoperative neutrophil-to-lymphocyte ratio and postoperative delirium: The PNDABLE and the PNDRFAP cohort studies

OBJECTIVES

In this study, the relationship between preoperative neutrophil-to-lymphocyte ratio (NLR) and Alzheimer-related biomarkers in cerebrospinal fluid (CSF) was investigated to determine whether high NLR is a potential risk factor for postoperative delirium (POD) and to evaluate its predictive efficacy.

METHODS

We selected 1000 patients from the perioperative neurocognitive disorder risk factor and prognosis (PNDRFAP) database and 999 patients from the perioperative neurocognitive disorder and biomarker lifestyle (PNDABLE) database. Patients in the PNDABLE database have been measured for Alzheimer-related biomarkers in CSF (Aβ40 , Aβ42 , P-tau, and tau protein). Mini-mental state examination was used to assess the preoperative mental status of patients. POD was diagnosed using the confusion assessment method and assessed for severity using the memorial delirium assessment scale. Logistic regression analysis was utilized to explore the association of preoperative NLR with POD. What's more, we also performed sensitivity analysis by adding corrected confounders, and the results were almost unchanged. Spearman's rank correlation was used to determine the associations between NLR and Alzheimer-related biomarkers. Mediation analyses with 10,000 bootstrapped iterations were used to explore the mediation effects. Finally, we use decision curves and the nomogram model to evaluate the efficacy of preoperative NLR in predicting POD; we also performed external validation using data from Qilu Hospital.

RESULT

Logistic regression results showed that an elevated preoperative NLR was a risk factor for the development of POD in patients (PNDRFAP: OR = 1.067, 95% CI 1.020-1.116; PNDABLE: OR = 1.182, 95% CI 1.048-1.335, p < .05). Spearman's rank correlation analysis showed a positive but weak correlation between NLR and P-tau/T-tau (R = .065). The mediating effect results indicate that NLR likely mediates the occurrence of POD through elevated tau protein levels (proportion: 47.47%). The results of the box plots showed statistically significant NLR and CSF biomarkers between the POD and non-POD (NPOD) groups (p < .05), with higher NLR, P-tau, and T-tau in the POD group than in the NPOD group. In contrast, the NPOD group had higher Aβ42 levels compared to the POD group. In addition, we used R package to plot the decision curve and nomogram both suggesting a good predictive effect of preoperative NLR on the occurrence of POD.

CONCLUSION

Elevated preoperative NLR levels may be a risk factor for POD and likely mediate the development of POD through elevated P-tau/T-tau levels.

The neutrophil-to-lymphocyte ratio is associated with mild cognitive impairment in community-dwelling older women aged over 70 years: a population-based cross-sectional study

Background

The neutrophil-to-lymphocyte ratio (NLR) is a marker of inflammation that can be obtained quickly, conveniently, and cheaply from blood samples. However, there is no research to explore the effects of sex and age on the relationship between the NLR and mild cognitive impairment (MCI) in community-dwelling older adults.

Methods

A total of 3,126 individuals aged over 60 years in Shanghai were recruited for face-to-face interviews, and blood samples were collected. MCI was assessed by the Mini-Mental State Examination (MMSE) and the Instrumental Activities of Daily Living (IADL) scale, and neutrophil count and lymphocyte counts were measured in fasting blood samples. The NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count.

Results

In females, the NLR in the MCI group was significantly higher than that in the cognitively normal group (2.13 ± 0.94 vs. 1.85 ± 0.83, p < 0.001) but not in men. Logistic regression showed that a higher NLR was an independent risk factor for MCI in women [odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.14-1.55]. In addition, the elevated NLR quartile was associated with an increased risk of MCI, especially in women older than 70 years (p value for trend = 0.012).

Conclusion

Compared with males, female MCI patients had a significantly higher NLR than cognitively normal controls. In addition, elevated NLR was found to be significantly associated with MCI risk in women older than 70 years. Therefore, elderly Chinese women with a higher NLR value may be the target population for effective prevention of MCI.

Investigating the Prognostic Role of Peripheral Inflammatory Markers in Mild Cognitive Impairment

Growing evidence suggests that neuroinflammation plays a critical role in the pathogenesis of neurodegenerative diseases. Peripheral markers of inflammation, including blood cell counts and their ratios, such as the neutrophil-to-lymphocyte ratio (NLR), have been reported as an easily accessible and reliable proxy of central nervous system inflammation. However, the role of peripheral inflammation in dementia and Mild Cognitive Impairment (MCI) still needs to be clarified. In the current study, we aimed to assess the prognostic role of the NLR and other peripheral markers of inflammation in a sample of 130 amnestic MCI, followed up for two to five years. The Mini-Mental state examination (MMSE) score at baseline and follow-up visits was used to assess global cognitive status at each visit and the degree of cognitive decline over time. Baseline peripheral markers of inflammation included blood cell counts and ratios, specifically the NLR, the platelet-to-lymphocyte ratio (PLR), the monocyte-to-lymphocyte ratio (MLR), and the systemic immune inflammation index (SII). After classifying subjects into CONVERTERS and non-CONVERTERS (respectively, patients converting to dementia and subjects showing stability at the last available follow-up), we compared peripheral markers of inflammation among groups ed correlated them with cognitive measures, testing the ability of significant factors to predict conversion to dementia. In our cohort, CONVERTERS showed lower baseline MMSE scores (p-value = 0.004) than non-CONVERTERS. In addition, CONVERTERS had statistically elevated NLR (p-value = 0.005), PLR (p-value = 0.002), and SII levels (p-value = 0.015), besides a lower number of lymphocytes (p-value = 0.004) compared with non-CONVERTERS. In a logistic regression analysis, baseline MMSE scores and NLR predicted conversion to dementia. Tertiles analysis showed that MCI with the highest NLR values had a higher conversion risk. Our study supports the hypothesis that a dysregulation of peripheral inflammation involving both lymphocytes and neutrophils may play a role in the pathogenesis of dementia, even at the early stages of neurodegeneration, as in the MCI condition.

Monocytes in the Characterization of Pain in Palliative Patients with Severe Dementia-A Pilot Study

In assessing and managing pain, when obtaining a self-report is impossible, therapeutic decision-making becomes more challenging. This study aimed to investigate whether monocytes and some membrane monocyte proteins, identified as a cluster of differentiation (CD), could be potential non-invasive peripheral biomarkers in identifying and characterizing pain in patients with severe dementia. We used 53 blood samples from non-oncological palliative patients, 44 patients with pain (38 of whom had dementia) and 0 without pain or dementia (controls). We evaluated the levels of monocytes and their subtypes, including classic, intermediate, and non-classic, and characterized the levels of specific phenotypic markers, namely CD11c, CD86, CD163, and CD206. We found that the relative concentrations of monocytes, particularly the percentage of classic monocytes, may be a helpful pain biomarker. Furthermore, the CD11c expression levels were significantly higher in patients with mixed pain, while CD163 and CD206 expression levels were significantly higher in patients with nociceptive pain. These findings suggest that the levels of monocytes, particularly the classic subtype, and their phenotype markers CD11c, CD163, and CD206 could serve as pain biomarkers in patients with severe dementia.

Effect of 8-Hydroxyguanine DNA Glycosylase 1 on the Function of Immune Cells

Excess reactive oxygen species (ROS) can cause an imbalance between oxidation and anti-oxidation, leading to the occurrence of oxidative stress in the body. The most common product of ROS-induced base damage is 8-hydroxyguanine (8-oxoG). Failure to promptly remove 8-oxoG often causes mutations during DNA replication. 8-oxoG is cleared from cells by the 8-oxoG DNA glycosylase 1 (OGG1)-mediated oxidative damage base excision repair pathway so as to prevent cells from suffering dysfunction due to oxidative stress. Physiological immune homeostasis and, in particular, immune cell function are vulnerable to oxidative stress. Evidence suggests that inflammation, aging, cancer, and other diseases are related to an imbalance in immune homeostasis caused by oxidative stress. However, the role of the OGG1-mediated oxidative damage repair pathway in the activation and maintenance of immune cell function is unknown. This review summarizes the current understanding of the effect of OGG1 on immune cell function.

Peripheral immune cell imbalance is associated with cortical beta-amyloid deposition and longitudinal cognitive decline

Neuroinflammation is believed to be a key process in Alzheimer's disease (AD) pathogenesis. Recently, the neutrophil-to-lymphocyte (NLR) and lymphocyte-to-monocyte ratios (LMR) have been proposed to be useful peripheral markers of inflammation. However, it is unclear how these inflammatory ratios relate to AD pathology, such as β-amyloid (Aβ) plaques and tau tangles. Using 18F-florbetapir and 18F-flortaucipir positron emission tomography (PET), we sought to determine how the NLR and LMR are associated with AD pathology both cross-sectionally and longitudinally. We further evaluated associations between the NLR and LMR and longitudinal cognitive decline. Using data from the Alzheimer's Disease Neuroimaging Initiative, we analyzed blood, PET, and cognitive data from 1544 subjects-405 cognitively normal, 838 with mild cognitive impairment (MCI), and 301 with AD. Associations between the NLR and LMR and Aβ and tau on PET were assessed using ordinary least-squares and mixed-effects regression models, while adjusting for age, sex, years of education, and apolipoprotein E ε2 or ε4 carrier status. Associations between the NLR and LMR and cognitive function, as measured by the AD Assessment Scale-Cognitive Subscale, 13-item version, were also assessed. MCI and AD subjects had higher NLR (p = 0.017, p < 0.001, respectively) and lower LMR (p = 0.013, p = 0.023). The NLR, but not the LMR, was significantly associated with Aβ (p = 0.028), suggesting that higher NLR was associated with greater Aβ deposition in the brain. Neither the NLR nor the LMR was associated with tau deposition (p > 0.05). A higher NLR was associated with greater longitudinal cognitive decline (p < 0.001). A higher ratio of peripheral neutrophils to lymphocytes, possibly reflecting an imbalance in innate versus adaptive immunity, is related to greater Aβ deposition and longitudinal cognitive decline. As the field moves toward blood-based biomarkers of AD, the altered balance of innate versus adaptive immunity could be a useful biomarker of underlying pathology and may also serve as a potential therapeutic target.

Association between the neutrophil to lymphocyte ratio and mild cognitive impairment in patients with type 2 diabetes

AIM

Evidence indicates that type 2 diabetes (T2D) is associated with mild cognitive impairment (MCI). Inflammation is a recognized sign of many neurodegenerative diseases. The neutrophil-to-lymphocyte ratio (NLR) is a novel and inexpensive marker of inflammation. The purpose of this study was to investigate the relationship between the NLR and MCI in patients with T2D.

METHODS

The sample for this study comprised 787 patients with T2D, including 411 patients with normal cognitive function and 376 patients with MCI. Blood biochemical parameters and routine blood indicators were determined by an automatic analyzer. The NLR was calculated as the neutrophil count divided by the lymphocyte count.

RESULTS

Compared with the control group, the MCI group was older and had a higher NLR but a lower education level and Montreal Cognitive Assessment (MoCA) score (p < 0.05). Spearman correlation and multiple linear regression analyses confirmed that the MoCA score was negatively associated with the NLR (p < 0.001). Multivariate logistic regression analysis demonstrated that the NLR was an independent risk factor for MCI in patients with T2D (p < 0.001). After adjusting for confounding factors, the risk of MCI for those in the third tertile of the NLR was 2.907 times higher than that of those in the first tertile of the NLR (OR = 2.907, 95%CI = 1.978-4.272, p < 0.001).

CONCLUSION

An elevated NLR is associated with MCI in patients with T2D.

The importance of Vitamin-D and Neutrophil-Lymphocyte Ratio for Alzheimer's Disease

Objective

Ischemia and inflammation play a role in the pathophysiology of Alzheimer's disease (AD). Plasma neutrophil-lymphocyte ratio (NLR), and 25- hydroxyvitamin D (vitamin D) were used as a biomarker for inflammation and atherosclerosis. The present study aimed to investigate a link between NLR, vitamin D and ischemia in AD.

Methods

The subjects with AD and control groups were enrolled to this retrospective study between 2017-2022 at Cukurova University Hospital. The cognitive assessment (MMSE), and blood tests (NLR, vitamin D) were collected from all subjects. In first part of the study, AD (n:132) and the control group (n:38) were compared. In second part of the study, magnetic resonance imaging (MRI) was used for evaluating ischemic lesions with scoring method of Fazekas. The control group (n:38) and AD subjects with mild ischemic lesions (Fazekas-1 and Fazekas-2) (n:64) were excluded. AD subjects with severe ischemic lesions (Fazekas-3) (n:34) and without ischemic lesions (Fazekas-0) (n:34) were compared again. SPSS 20.0 was used for all analyses. The threshold for statistical significance was set at 0.05.

Results

In the first part of the study, 132 AD patients (69 female and 63 male; mean age 70.83±9.35 (49-87) and age-matched 38 controls were compared. The mean NLR in AD [2.96±2.46 (1.17-19.43)] was higher than the control group [1.9±0.66 (0.9-3.56)] (p=0.005). In the second part of the study, the mean Vitamin D of Fazekas-3 AD group [16.15±9.64 (4.7-35)] was lower than Fazekas-0 AD group [16.27±6.81(4.6-29.7)] (p=0.024).

Conclusion

NLR was higher in AD while there was no difference between the Fazekas-0 and Fazekas-3 AD groups. Vitamin D was lower in the Fazekas-3 AD group. These data suggested that NLR increased independently of ischemia in AD. Also vitamin D deficiency could trigger ischemia in AD.

Machine Learning-Based Routine Laboratory Tests Predict One-Year Cognitive and Functional Decline in a Population Aged 75+ Years

BACKGROUND

Cognitive and functional decline are common problems in older adults, especially in those 75+ years old. Currently, there is no specific plasma biomarker able to predict this decline in healthy old-age people. Machine learning (ML) is a subarea of artificial intelligence (AI), which can be used to predict outcomes Aim: This study aimed to evaluate routine laboratory variables able to predict cognitive and functional impairment, using ML algorithms, in a cohort aged 75+ years, in a one-year follow-up study.

METHOD

One hundred and thirty-two older adults aged 75+ years were selected through a community-health public program or from long-term-care institutions. Their functional and cognitive performances were evaluated at baseline and one year later using a functional activities questionnaire, Mini-Mental State Examination, and the Brief Cognitive Screening Battery. Routine laboratory tests were performed at baseline. ML algorithms-random forest, support vector machine (SVM), and XGBoost-were applied in order to describe the best model able to predict cognitive and functional decline using routine tests as features.

RESULTS

The random forest model showed better accuracy than other algorithms and included triglycerides, glucose, hematocrit, red cell distribution width (RDW), albumin, hemoglobin, globulin, high-density lipoprotein cholesterol (HDL-c), thyroid-stimulating hormone (TSH), creatinine, lymphocyte, erythrocyte, platelet/leucocyte (PLR), and neutrophil/leucocyte (NLR) ratios, and alanine transaminase (ALT), leukocyte, low-density lipoprotein cholesterol (LDL-c), cortisol, gamma-glutamyl transferase (GGT), and eosinophil as features to predict cognitive decline (accuracy = 0.79). For functional decline, the most important features were platelet, PLR and NLR, hemoglobin, globulin, cortisol, RDW, glucose, basophil, B12 vitamin, creatinine, GGT, ALT, aspartate transferase (AST), eosinophil, hematocrit, erythrocyte, triglycerides, HDL-c, and monocyte (accuracy = 0.92).

CONCLUSIONS

Routine laboratory variables could be applied to predict cognitive and functional decline in oldest-old populations using ML algorithms.

Neuroimmune mechanisms underlying Alzheimer's disease: Insights into central and peripheral immune cell crosstalk

Alzheimer's disease (AD) is a highly life-threatening neurodegenerative disease. Dysregulation of the immune system plays a critical role in promoting AD, which has attracted extensive attention recently. Central and peripheral immune responses are involved in the pathogenesis of AD. Immune changes precede Aβ-associated senile plaque formation and tau-related neurofibrillary tangles, which are the recognised pathological features of AD. Therefore, elucidating immune-related mechanisms underlying the development of AD can help to prevent and treat AD at the source by blocking its progression before the development of pathological changes. To understand the specific pathogenesis of AD, it is important to examine the role of central and peripheral immunity in AD. This review summarises immune-related mechanisms underlying the pathogenesis of AD, focusing on the effect of various central and peripheral immune cells, and describes the possible crosstalk between central and peripheral immunity during the development of AD. This review provides novel insights into the treatment of AD and offers a new direction for immune-related research on AD in the future.

The neuroimmune axis of Alzheimer's disease

Alzheimer's disease (AD) is a genetically complex and heterogeneous disorder with multifaceted neuropathological features, including β-amyloid plaques, neurofibrillary tangles, and neuroinflammation. Over the past decade, emerging evidence has implicated both beneficial and pathological roles for innate immune genes and immune cells, including peripheral immune cells such as T cells, which can infiltrate the brain and either ameliorate or exacerbate AD neuropathogenesis. These findings support a neuroimmune axis of AD, in which the interplay of adaptive and innate immune systems inside and outside the brain critically impacts the etiology and pathogenesis of AD. In this review, we discuss the complexities of AD neuropathology at the levels of genetics and cellular physiology, highlighting immune signaling pathways and genes associated with AD risk and interactions among both innate and adaptive immune cells in the AD brain. We emphasize the role of peripheral immune cells in AD and the mechanisms by which immune cells, such as T cells and monocytes, influence AD neuropathology, including microglial clearance of amyloid-β peptide, the key component of β-amyloid plaque cores, pro-inflammatory and cytotoxic activity of microglia, astrogliosis, and their interactions with the brain vasculature. Finally, we review the challenges and outlook for establishing immune-based therapies for treating and preventing AD.

Telomere and mitochondria mediated the association between dietary inflammatory index and mild cognitive impairment: A prospective cohort study

BACKGROUND

Diet and chronic inflammation might play a major role in the pathogenesis of mild cognitive impairment (MCI). In addition, peripheral blood leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNAcn) might mediate the relationship between inflammation and MCI risk. The purpose of the present study is to evaluate whether inflammatory potential of diet assessed by dietary inflammatory index (DII), chronic inflammation, peripheral blood LTL, and mtDNAcn were associated with the risk of MCI.

RESULTS

A population-based cohort study was conducted with a total of 2944 participants. During a median follow-up of 2 years, 438 (14.90%) individuals were new-onset MCI. After adjustment, a higher score of DII (hazard ratio [HR]: 1.056, 95% CI: 1.005, 1.109), a higher log systemic immune inflammation index (SII) (HR: 1.333, 95% CI: 1.089, 1.633) and log system inflammation response index (SIRI) (HR: 1.487, 95% CI: 1.024, 2.161) predicted elevated risk of MCI. An increased mtDNAcn (HR: 0.843, 95% CI: 0.712, 0.997), but not LTL, predicted a decreased risk of MCI. Negative associations of log SII with LTL (β:-0.359, 95% CI: -0.445, -0.273) and mtDNAcn (β:-0.048, 95% CI: -0.090, -0.006) were found. Additionally, negative associations of log SIRI with LTL (β: -0.035, 95% CI: -0.052, -0.017) and mtDNAcn (β:-0.136, 95% CI: -0.216, -0.056) were also found. Path analysis suggested that SIRI, LTL, and mtDNAcn, in series, have mediation roles in the association between DII score and MCI risk.

CONCLUSIONS

Higher DII, SII, and SIRI might predict a greater risk of MCI, while a longer LTL and an increased mtDNAcn were linked to a reduced risk of MCI among the older population. LTL and mtDNAcn could play mediation roles in the association between DII and MCI risk.

Identification of Two CDK5R1-Related Subtypes and Characterization of Immune Infiltrates in Alzheimer's Disease Based on an Integrated Bioinformatics Analysis

Background

Alzheimer's disease (AD) is a neurodegenerative disorder and the major cause of senile dementia. The Reelin pathway has been involved in both learning and AD pathogenesis. However, the specific Reelin-related gene signature during the pathological process remains unknown.

Methods

Reelin-related gene (CDK5R1) expression was analyzed using the GEO datasets. The relevant genes of CDK5R1 were identified using differential expression analysis and weighted gene correlation network analysis (WGCNA) based on the GSE43850 dataset. ConsensusClusterPlus analysis was applied to identify subtypes (C1 and C2) of AD. The CIBERSORT algorithm was used to assess the immune cell infiltration between the two AD subtypes.

Results

CDK5R1 was downregulated in AD. 244 differentially expressed CDK5R1-related genes (DECRGs) between the two subgroups were mainly enriched in GABAergic synapse, neuroactive ligand-receptor interaction, synapse organization, neurotransmitter transport, etc. Furthermore, the GSVA results indicated that immune-related pathways were significantly enriched in the C1 subgroup. Interestingly, 10 Reelin pathway-related genes (CRK, DAB2IP, LRP8, RELN, STAT5A, CDK5, CDK5R1, DAB1, FYN, and SH3KBP1) were abnormally expressed between the two subgroups. The proportion of T cell gamma delta, monocytes, macrophage M2, and dendritic cells activated decreased from C1 to C2, while the proportion of plasma cells, T cell follicular helper, and NK cells activated increased.

Conclusion

Two CDK5R1-related subtypes of AD were identified, helping us to better understand the role of CDK5R1 in the pathological process of AD.

Blood Leukocyte Counts in Alzheimer Disease

IMPORTANCE

Emerging evidence implicates a role for neuroinflammation in Alzheimer disease (AD) pathogenesis, predominantly involving the innate immune system. Blood leukocyte counts are easily accessible markers of immune function; however, their association with the risk of AD is unknown.

OBJECTIVE

To investigate the observational and genetic associations between types of blood leukocytes and risk of AD.

DESIGN, SETTING, AND PARTICIPANTS

In a cohort study comprising observational and genetic analyses, the Copenhagen General Population Study prospective cohort (n = 101 582) was used for the observational analyses. For the genetic studies, nonlinearity was first evaluated for the association between leukocyte cell counts and AD risk using individual-level data from the UK Biobank (n = 365 913). Subsequently, a 2-sample mendelian randomization framework was applied using genetic instruments for blood leukocyte counts (n = 563 085); for AD, the European Alzheimer & Dementia Biobank was used, including 85 934 individuals with AD and 401 577 controls and the International Genomics of Alzheimer's Project, including 21 982 individuals with AD and 41 944 controls.

EXPOSURES

Observational and genetically determined types of blood leukocyte counts.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) and 95% CIs for AD of cell count percentile groups in observational studies and odds ratios (ORs) and 95% CIs for AD per 1 SD genetically determined cell counts.

RESULTS

This cohort study included 101 582 participants (55 891 [55.0%] women) with a median age of 58 years (IQR, 48-67 years); of these, 1588 individuals developed AD. Multivariable-adjusted HRs for participants in the less than 5th vs the 25th to 75th (reference) percentile group were 1.24 (95% CI, 0.99-1.54) for blood monocytes and 1.25 for blood eosinophils (95% CI, 1.05-1.50). For participants in the greater than 95th vs the 25th to 75th percentile group, the HR was 1.30 (95% CI, 1.06-1.61) for blood neutrophils. Genetically, no evidence favored possible nonlinear associations. The ORs for AD per 1-SD decrease in genetically determined blood monocytes were 1.04 (95% CI, 1.00-1.10) in the European Alzheimer & Dementia Biobank consortium and 1.09 (95% CI, 1.01-1.17) in the International Genomics of Alzheimer's Project consortium. Using mendelian randomization, sensitivity analyses and multivariable analysis showed similar results.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that low blood monocyte counts are associated with increased AD risk. These findings highlight a potential role of the innate immune system in AD pathogenesis.

Lymphocyte Count and Neutrophil-to-Lymphocyte Ratio Are Associated with Mild Cognitive Impairment in Parkinson’s Disease: A Single-Center Longitudinal Study

Lymphocyte count and neutrophil-to-lymphocyte ratio (NLR) may represent useful biomarkers of Parkinson’s disease (PD), but their role in PD-related mild cognitive impairment (MCI) has not been fully elucidated. The present study aimed to confirm whether these immunological measures can discriminate PD patients from healthy controls (HC) and establish their feasibility as prognostic biomarkers of MCI in PD. Immunological data at baseline were analyzed in 58 drug-naïve PD patients and 58 HC matched 1:1 for age, sex, and cardiovascular comorbidities. We selected a subgroup of 51 patients from this initial cohort who underwent longitudinal neuropsychological assessments through the Addenbrooke’s Cognitive Examination Revised (ACE-R) test. We considered the last examination available to analyze the relationship between ACE-R test scores and immunological measures. We found that lymphocyte count was lower and NLR higher in PD than HC (p = 0.006, p = 0.044), with AUC = 0.649 and 0.608, respectively. Secondly, in PD-MCI there were significantly higher levels of circulating lymphocytes (p = 0.002) and lower NLR (p = 0.020) than PD with normal cognitive status (PD-NC). Correlations between lymphocyte count and ACE-R total score and memory subitem (r = −0.382, p = 0.006; r = −0.362, p = 0.01), as well as between NLR and ACE-R total score and memory subitem (r = 0.325, p = 0.02; r = 0.374, p = 0.007), were also found. ROC curve analysis showed that lymphocyte count and NLR displayed acceptable discrimination power of PD-MCI with AUC = 0.759 and 0.691, respectively. In conclusion, we suggest that an altered peripheral immune phenotype could foster cognitive decline development in PD, thus opening the possibility of immune-targeting strategies to tackle this disabling non-motor feature.

Blood-based biomarker in Parkinson's disease: potential for future applications in clinical research and practice

The clinical presentation of Parkinson's disease (PD) is both complex and heterogeneous, and its precise classification often requires an intensive work-up. The differential diagnosis, assessment of disease progression, evaluation of therapeutic responses, or identification of PD subtypes frequently remains uncertain from a clinical point of view. Various tissue- and fluid-based biomarkers are currently being investigated to improve the description of PD. From a clinician's perspective, signatures from blood that are relatively easy to obtain would have great potential for use in clinical practice if they fulfill the necessary requirements as PD biomarker. In this review article, we summarize the knowledge on blood-based PD biomarkers and present both a researcher's and a clinician's perspective on recent developments and potential future applications.

β-Amyloid promotes platelet activation and activated platelets act as bridge between risk factors and Alzheimer's disease

Alzheimer's disease (AD) is an evolving challenge that places an enormous burden on families and society. The presence of obvious brain β-amyloid (Aβ) deposition is a premise to diagnose AD, which induces the subsequent tau hyperphosphorylation and neurodegeneration. Platelets are the primary source of circulating amyloid precursor protein (APP). Upon activation, they can secrete significant amounts of Aβ into the blood, which can be actively transported to the brain across the blood-brain barrier and promote amyloid deposition. In this review, we summarized the changes in the platelet APP metabolic pathway in patients with AD and further comprehensively explored the targets and downstream events of Aβ-activated platelets. In addition, we attempted to clarify whether patients with AD are in a state of general platelet activation, with inconsistent results. Considering the increasingly evident bidirectional relationship between AD and vascular events, we speculate that the AD pathology alone seems to be insufficient to induce the general activation of platelets; however, the intervention of third-party factors, such as atherosclerosis, exposes the extracellular matrix and leads to platelet activation, further promoting AD progression. Therefore, we proposed a framework in which the relationship between platelets and AD is indirect and mediated by vascular factors. Therapies targeting platelets and interventions for vascular risk factors are likely to contribute to the prevention and treatment of AD.

Integrative analysis of DNA methylation and gene expression data for the diagnosis and underlying mechanism of Parkinson’s disease

Background

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disorder and the leading cause of disability in the daily activities. In the management of PD, accurate and specific biomarkers in blood for the early diagnosis of PD are urgently needed. DNA methylation is one of the main epigenetic mechanisms and associated with the gene expression and disease initiation of PD. We aimed to construct a methylation signature for the diagnosis of PD patients, and explore the potential value of DNA methylation in therapeutic options.

Materials and methods

Whole blood DNA methylation and gene expression data of PD patients as well as healthy controls were extracted from Gene Expression Omnibus database. Next, differentially expressed genes (DEGs) and differentially methylated genes (DMGs) between PD patients and healthy controls were identified. Least absolute shrinkage and selection operator cox regression analysis was carried out to construct a diagnostic signature based on the overlapped genes. And, the receiver operating characteristic (ROC) curves were drawn and the area under the curve (AUC) was used to assess the diagnostic performance of the signature in both the training and testing datasets. Finally, gene ontology and gene set enrichment analysis were subsequently carried out to explore the underlying mechanisms.

Results

We obtained a total of 9,596 DMGs, 1,058 DEGs, and 237 overlapped genes in the whole blood between PD patients and healthy controls. Eight methylation-driven genes (HIST1H4L, CDC42EP3, KIT, GNLY, SLC22A1, GCM1, INO80B, and ARHGAP26) were identified to construct the gene expression signature. The AUCs in predicting PD patients were 0.84 and 0.76 in training dataset and testing dataset, respectively. Additionally, eight methylation-altered CpGs were also identified to construct the CpGs signature which showed a similarly robust diagnostic capability, with AUCs of 0.8 and 0.73 in training dataset and testing dataset, respectively.

Conclusion

We conducted an integrated analysis of the gene expression and DNA methylation data, and constructed a methylation-driven genes signature and a methylation-altered CpGs signature to distinguish the patients with PD from healthy controls. Both of them had a robust prediction power and provide a new insight into personalized diagnostic and therapeutic strategies for PD.

RNA-Seq Profiling of Neutrophil-Derived Microvesicles in Alzheimer's Disease Patients Identifies a miRNA Signature That May Impact Blood-Brain Barrier Integrity

(1) Background: Systemic infection is associated with increased neuroinflammation and accelerated cognitive decline in AD patients. Activated neutrophils produce neutrophil-derived microvesicles (NMV), which are internalised by human brain microvascular endothelial cells and increase their permeability in vitro, suggesting that NMV play a role in blood–brain barrier (BBB) integrity during infection. The current study investigated whether microRNA content of NMV from AD patients is significantly different compared to healthy controls and could impact cerebrovascular integrity. (2) Methods: Neutrophils isolated from peripheral blood samples of five AD and five healthy control donors without systemic infection were stimulated to produce NMV. MicroRNAs isolated from NMV were analysed by RNA-Seq, and online bioinformatic tools were used to identify significantly differentially expressed microRNAs in the NMV. Target and pathway analyses were performed to predict the impact of the candidate microRNAs on vascular integrity. (3) Results: There was no significant difference in either the number of neutrophils (p = 0.309) or the number of NMV (p = 0.3434) isolated from AD donors compared to control. However, 158 microRNAs were significantly dysregulated in AD NMV compared to controls, some of which were associated with BBB dysfunction, including miR-210, miR-20b-5p and miR-126-5p. Pathway analysis revealed numerous significantly affected pathways involved in regulating vascular integrity, including the TGFβ and PDGFB pathways, as well as Hippo, IL-2 and DNA damage signalling. (4) Conclusions: NMV from AD patients contain miRNAs that may alter the integrity of the BBB and represent a novel neutrophil-mediated mechanism for BBB dysfunction in AD and the accelerated cognitive decline seen as a result of a systemic infection.

Prediction of Early Mortality Among Children With Moderate or Severe Traumatic Brain Injury Based on a Nomogram Integrating Radiological and Inflammation-Based Biomarkers

Inflammation-based scores have been increasingly used for prognosis prediction in neurological diseases. This study aimed to investigate the predictive value of inflammation-based scores combined with radiological characteristics in children with moderate or severe traumatic brain injury (MS-TBI). A total of 104 pediatric patients with MS-TBI were retrospectively enrolled and randomly divided into training and validation cohorts at a 7:3 ratio. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of prognosis in pediatric patients with MS-TBI. A prognostic nomogram was constructed, and its predictive performance was validated in both the training and validation cohorts. Sex, admission platelet-to-lymphocyte ratio, and basal cistern status from initial CT findings were identified as independent prognostic predictors for children with MS-TBI in multivariate logistic analysis. Based on these findings, a nomogram was then developed and its concordance index values were 0.918 [95% confidence interval (CI): 0.837-0.999] in the training cohort and 0.86 (95% CI: 0.70-1.00) in the validation cohort, which significantly outperformed those of the Rotterdam, Marshall, and Helsinki CT scores. The proposed nomogram, based on routine complete blood count and initial CT scan findings, can contribute to individualized prognosis prediction and clinical decision-making in children with MS-TBI.

Association of Peripheral Blood Cell Profile With Alzheimer's Disease: A Meta-Analysis

Background

Inflammation and immune dysfunction play significant roles in the pathogenesis of Alzheimer's disease (AD)-related dementia. Changes in peripheral blood cell profiles are a common manifestation of inflammation and immune dysfunction and have been reported in patients with AD or mild cognitive impairment (MCI). We systematically evaluated the association of peripheral blood cell counts and indices with AD or MCI through a meta-analysis.

Methods

We electronically searched sources to identify all case–control trials comparing peripheral blood cell counts and/or lymphocyte subsets between patients with AD or MCI and healthy controls (HCs). Meta-analyses were used to estimate the between-group standardized mean difference (SMD) and 95% confidence interval (CI).

Results

A total of 36 studies involving 2,339 AD patients, 608 MCI patients, and 8,352 HCs were included. AD patients had significantly decreased lymphocyte counts (SMD −0.345, 95% CI [−0.545, −0.146], P = 0.001) and significantly increased leukocyte counts (0.140 [0.039, 0.241], P = 0.006), neutrophil counts (0.309 [0.185, 0.434], P = 0.01), and neutrophil–lymphocyte ratio (NLR) (0.644 [0.310, 0.978], P < 0.001) compared to HCs. Similarly, significantly increased leukocyte counts (0.392 [0.206, 0.579], P < 0.001), NLR (0.579 [0.310, 0.847], P < 0.001), and neutrophil counts (0.248 [0.121, 0.376], P < 0.001) were found in MCI patients compared with HCs. A significantly decreased percentage of B lymphocytes (−1.511 [−2.775, −0.248], P = 0.019) and CD8⁺ T cells (−0.760 [−1.460, −0.061], P = 0.033) and a significantly increased CD4/CD8 ratio (0.615 [0.074, 1.156], P = 0.026) were observed in AD patients compared to HCs. Furthermore, significant changes in hemoglobin level and platelet distribution width were found in patients with AD or MCI compared with HCs. However, no significant difference was found between AD or MCI patients and HCs in terms of platelet counts, mean corpuscular volume, red cell distribution width, mean platelet volume, and CD4⁺ T, CD3⁺ T, or natural killer cell counts.

Conclusion

Changes in peripheral blood cell profiles, particularly involving leukocyte, lymphocyte, neutrophil, and CD8⁺ T cell counts, as well as the NLR and the CD4/CD8 ratio, are closely associated with AD. The diagnostic relevance of these profiles should be investigated in future.

Integrative analysis of eQTL and GWAS summary statistics reveals transcriptomic alteration in Alzheimer brains

BACKGROUND

Large-scale genome-wide association studies have successfully identified many genetic variants significantly associated with Alzheimer's disease (AD), such as rs429358, rs11038106, rs723804, rs13591776, and more. The next key step is to understand the function of these SNPs and the downstream biology through which they exert the effect on the development of AD. However, this remains a challenging task due to the tissue-specific nature of transcriptomic and proteomic data and the limited availability of brain tissue.In this paper, instead of using coupled transcriptomic data, we performed an integrative analysis of existing GWAS findings and expression quantitative trait loci (eQTL) results from AD-related brain regions to estimate the transcriptomic alterations in AD brain.

RESULTS

We used summary-based mendelian randomization method along with heterogeneity in dependent instruments method and were able to identify 32 genes with potential altered levels in temporal cortex region. Among these, 10 of them were further validated using real gene expression data collected from temporal cortex region, and 19 SNPs from NECTIN and TOMM40 genes were found associated with multiple temporal cortex imaging phenotype.

CONCLUSION

Significant pathways from enriched gene networks included neutrophil degranulation, Cell surface interactions at the vascular wall, and Regulation of TP53 activity which are still relatively under explored in Alzheimer's Disease while also encouraging a necessity to bind further trans-eQTL effects into this integrative analysis.

Effects of Rosemary Oil (Rosmarinus officinalis) supplementation on the fate of the transplanted human olfactory bulb neural stem cells against ibotenic acid-induced neurotoxicity (Alzheimer model) in rat

Rosemary oil (ROO) is known to have multiple pharmacological effects: it is an antioxidant, anti-inflammatory, and cytoprotective. In the present study, we examined the effects of ROO on Human olfactory bulb neuronal stem cells (hOBNSCs) after their transplantation into rats, with the ibotenic (IBO) acid-induced cognitive deficit model. After 7 weeks, cognitive functions were assessed using the Morris water maze (MWM). After two months blood and hippocampus samples were collected for biochemical, gene expression, and histomorphometric analyses. Learning ability and memory function were significantly enhanced (P < 0.05) after hOBNSCs transplantation and were nearly returned to normal in the treated group. The IBO acid injection was associated with a significant decline (P < 0.05) of total leukocyte count (TLC) and a significant increase (P < 0.05) in total and toxic neutrophils. As well, the level of IL-1β, TNF-α CRP in serum and levels of MDA and NO in hippocampus tissue were significantly elevated (P < 0.05), while antioxidant markers (CAT, GSH, and SOD) were reduced (P < 0.05) in treated tissue compared to controls. The administration of ROO before or with cell transplantation attenuated all these parameters. In particular, the level of NO nearly returned to normal when rosemary was administrated before cell transplantation. Gene expression analysis revealed the potential protective effect of ROO and hOBNSCs via down-expression of R-βAmyl and R- CAS 3 and R-GFAP genes. The improvement in the histological organization of the hippocampus was detected after the hOBNSCs transplantation especially in h/ROO/hOBNSCs group.

Association of peripheral immunity with cognition, neuroimaging, and Alzheimer's pathology

Background

Neuroinflammation has been considered to be a driving force of Alzheimer’s disease. However, the association between peripheral immunity and AD has been rarely investigated.

Methods

Separate regression analyses were conducted to explore the associations among peripheral immune markers and cognition, neuroimaging, and AD pathology. Causal mediation analyses were used to investigate whether the associations with cognition were mediated by AD pathology.

Results

A total of 1107 participants (43.9% female, mean age of 73.2 years) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) were included. Regression analyses indicated that elevated neutrophils (NEU) count and neutrophil-lymphocyte ratio (NLR) were associated with lower levels of global cognition, memory function (MEM), and executive function (EF), and reduced brain metabolism by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) as well as greater ventricular volume. An elevated NLR was associated with a lower level of β-amyloid (Aβ) and a higher level of total tau (T-tau) in cerebrospinal fluid (CSF), smaller hippocampal volume (HV), and lesser entorhinal cortex (EC) thickness. On the contrary, an elevated level of lymphocytes (LYM) was associated with a higher level of Aβ and a lower level of T-tau in CSF, better cognition, and less atrophy of brain regions (ventricular volume, HV, and EC thickness). The associations of LYM and NLR with cognition were mediated by Aβ and T-tau pathology (proportion: 18%~64%; p < 0.05).

Conclusions

We revealed that two types of peripheral immune cells (NEU and LYM) and the ratio of these two cell types (NLR) had associations with cognition, neuroimaging, and AD pathology. The associations might be mediated by Aβ and tau pathology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-00968-y.

Investigation of the peripheral inflammation (neutrophil-lymphocyte ratio) in two neurodegenerative diseases of the central nervous system

INTRODUCTION

Alzheimer's disease (AD), and idiopathic Parkinson's disease (IPD) are the neurodegenerative diseases of the central nervous system (CNS). Cognitive impairment is on the forefront in AD. However, IPD is a movement disorder. Inflammation was suggested to have an effect in the pathophysiology of these two diseases. Neutrophil-lymphocyte ratio (NLR) was shown to be a possible marker showing the peripheral inflammation. We aimed to investigate the NLR of patiens with the diagnosis of AD, and IPD, and individuals with no neurodegenerative disease.

MATERIALS AND METHODS

A total of 100 patients with the diagnosis of IPD, and 94 with diagnosis of AD, and 61 healthy controls were included into the study. All the demographic, clinical, and laboratory data were retrospectively obtained from the hospital automated database system.

RESULTS

The NLR in the IPD group was found statistically significantly higher compared with the control group and the AD group (p < 0.001, p = 0.04, respectively). The age-adjusted values were statistically analyzed because of age difference. No statistically significant difference was detected between AD and control groups in terms of NLR (p = 0.6). The age-adjusted NLR value in the Parkinson's group was found significantly higher compared to the control group (p = 0.02) and Alzheimer's group (p = 0.03).

DISCUSSION

Chronic inflammation has an important role in the emergence and progression of the chronic neurodegenerative diseases of the CNS. Our results show that the inflammation in the peripheral blood in IPD was more significant compared with the inflammation in AD.

Identification of Hub Genes and Immune Cell Infiltration Characteristics in Alzheimer's Disease

The purpose of this study was to identify hub genes closely correlated with Alzheimer's disease (AD) and their association with immune cell infiltration. In this work, 119 overlapping differentially expressed genes (DEGs) were obtained from GSE5281 and GSE122063 datasets through differential expression analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the 119 DEGs, revealing some important biological functions and key pathways. AD immune cell infiltration analysis revealed a significant difference in the proportion of immune cells between the AD group and the control group. Finally, correlation analysis between target hub genes and immune cells indicated that GFAP had a positive or negative correlation with some specific immune cells. Our results provided useful clues, which will help to explain the molecular mechanism of AD and search for precise prognostic markers and potential therapeutic targets.

Leukocyte-derived ratios are associated with late-life any type dementia: a cross-sectional analysis of the Mugello study

Immunosenescence, vascular aging, and brain aging, all characterized by elevated levels of inflammatory markers, are thought to share a common pathogenetic pathway: inflamm-aging. Retrospective cross-sectional analysis was conducted using data from the Mugello study (Tuscany, Italy), a representative Italian cohort of free-living nonagenarians. to assess the association between specific peripheral inflammation markers derived from white blood cell counts, and the diagnosis of dementia. All the variables of interest were reported for 411 subjects (110 males and 301 females) out of 475 enrolled in the study. Anamnestic dementia diagnosis was obtained from clinical certificate and confirmed by a General Practitioner, whereas leukocyte ratios were directly calculated from white blood cell counts. Body mass index and comorbidities were considered potential confounders. Diagnosis of any type dementia was certified in 73 cases (17.8%). Subjects affected by dementia were older, more frequently reported a previous stroke, had lower body mass index, and lower Mini-Mental-State-Examination score. Moreover, they had a higher lymphocyte count and lymphocyte-to-monocyte ratio compared to the non-demented nonagenarians. We found that higher levels of lymphocyte counts are cross-sectionally associated with a clinical diagnosis of dementia. Furthermore, lymphocyte-to-monocyte ratio is directly associated with any type of dementia, independently of age, sex, lymphocyte count, and comorbidities. Lymphocyte-to-monocyte ratio may be considered a marker of immunological changes in the brain of dementia patients; moreover, it is low-cost, and easily available, thus enabling comparisons among different studies and populations, although the timeline and the extent of lymphocyte-to-monocyte ratio role in dementia development must be further investigated.

Complete blood cell count-derived ratios can be useful biomarkers for neurological diseases

Complete blood cell count-derived parameters such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) have recently shown to be highly sensitive biomarkers. Their usefulness has been proven as prognostic factors in several cancers, in the stratification of mortality in major cardiac events, as predictors and markers of infectious or inflammatory pathologies, and in many other conditions. Surprisingly, the study of these biomarkers in neurological diseases is somewhat limited. This paper aims to take stock of the data present in the literature regarding the complete blood cell count-derived ratios in this group of pathologies and to formulate a hypothesis, based on the most recent data concerning innate and acquired immunity, on which diseases of the nervous system could benefit in diagnostic and prognostic terms from the in-depth study of these new biomarkers.

Peripheral Immune Profile and Neutrophil-to-Lymphocyte Ratio in Parkinson's Disease

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) in peripheral blood is a well-established inflammatory marker, but its role in Parkinson's disease (PD) remains unclear.

OBJECTIVES

To determine whether a different peripheral immune profile and NLR were present in PD patients.

METHODS

We conducted a case-control study that included 377 PD patients and 355 healthy controls (HCs). Leukocytes, subpopulations, and the NLR were measured. Multivariate linear regression analyses were applied to determine the differences between groups and the association between NLR and clinical characteristics in PD. A meta-analysis was performed to clarify the association between NLR and PD.

RESULTS

In our case-control study, the NLR was significantly higher in PD patients compared with HCs (2.47 ± 1.1 vs. 1.98 ± 0.91, P < 0.001). No association between NLR and age at onset, disease severity, or disease duration was found. The meta-analysis showed that the NLR was likely to be higher in PD patients.

CONCLUSIONS

PD patients had an altered peripheral immune profile and a higher NLR compared with HCs. © 2021 International Parkinson and Movement Disorder Society.

Biomarkers of Senescence during Aging as Possible Warnings to Use Preventive Measures

Human life expectancy is increasing significantly over time thanks to the improved possibility for people to take care of themselves and the higher availability of food, drugs, hygiene, services, and assistance. The increase in the average age of the population worldwide is, however, becoming a real concern, since aging is associated with the rapid increase in chronic inflammatory pathologies and degenerative diseases, very frequently dependent on senescent phenomena that occur alongside with senescence. Therefore, the search for reliable biomarkers that can diagnose the possible onset or predict the risk of developing a disease associated with aging is a crucial target of current medicine. In this review, we construct a synopsis of the main addressable biomarkers to study the development of aging and the associated ailments.

Common Peripheral Immunity Mechanisms in Multiple Sclerosis and Alzheimer's Disease

Neurodegenerative diseases are closely related to inflammatory and autoimmune events, suggesting that the dysregulation of the immune system is a key pathological factor. Both multiple sclerosis (MS) and Alzheimer's disease (AD) are characterized by infiltrating immune cells, activated microglia, astrocyte proliferation, and neuronal damage. Moreover, MS and AD share a common pro-inflammatory signature, characterized by peripheral leukocyte activation and transmigration to the central nervous system (CNS). MS and AD are both characterized by the accumulation of activated neutrophils in the blood, leading to progressive impairment of the blood–brain barrier. Having migrated to the CNS during the early phases of MS and AD, neutrophils promote local inflammation that contributes to pathogenesis and clinical progression. The role of circulating T cells in MS is well-established, whereas the contribution of adaptive immunity to AD pathogenesis and progression is a more recent discovery. Even so, blocking the transmigration of T cells to the CNS can benefit both MS and AD patients, suggesting that common adaptive immunity mechanisms play a detrimental role in each disease. There is also growing evidence that regulatory T cells are beneficial during the initial stages of MS and AD, supporting the link between the modulatory immune compartments and these neurodegenerative disorders. The number of resting regulatory T cells declines in both diseases, indicating a common pathogenic mechanism involving the dysregulation of these cells, although their precise role in the control of neuroinflammation remains unclear. The modulation of leukocyte functions can benefit MS patients, so more insight into the role of peripheral immune cells may reveal new targets for pharmacological intervention in other neuroinflammatory and neurodegenerative diseases, including AD.

Elevated Urine Leukotriene E4 Is Associated With Worse Objective Markers in Nasal Polyposis Patients

OBJECTIVES

Urine leukotriene E4 (uLTE4) is a biomarker of leukotriene synthesis and is elevated in patients with aspirin-exacerbated respiratory disease (AERD). It can also be useful to help delineate aspirin-tolerant chronic rhinosinusitis with nasal polyposis (CRSwNP) patients from AERD patients. The purpose of this study is to determine if uLTE4 biomarker levels are associated with objective and subjective markers of disease severity in patients with CRSwNP.

METHODS

A retrospective analysis of CRSwNP patients who underwent uLTE4 testing was completed to determine the association of uLTE4 levels to markers of disease severity. uLTE4 levels, as well as presenting subjective (Sinonasal Outcome Test 22 [SNOT22] scores, asthma control test [ACT] scores) and objective data (Lund-Mackay CT score, spirometry and lab values) were collected.

RESULTS

Among the 157 CRSwNP patients who met inclusion criteria, uLTE4 levels were associated with history of asthma (P < .001), aspirin sensitivity (P < .001), worse Lund-Mackay CT scores (P = .002) and other objective markers of disease severity including serum IgE (P = .05), presenting blood eosinophil level (P < .001), and the highest recorded eosinophil level (P < .001). In subgroup analysis, associations of uLTE4 to disease markers had stronger correlations in the aspirin sensitive CRSwNP group (R range 0.31-0.52) than the aspirin tolerant CRSwNP group (R range -0.30-0.24). uLTE4 levels were not associated with subjective symptom scores (SNOT22 and ACT scores).

CONCLUSION

Elevated uLTE4 biomarker levels are associated with worsened objective markers of disease severity in CRSwNP patients but not patient-reported symptom measures.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:961-966, 2021.

The neutrophil-to-lymphocyte ratio in Alzheimer's disease: Current understanding and potential applications

Alzheimer's disease (AD) is a chronic neurodegenerative disorder affecting millions of people, and its prevalence is expected to continue to grow in the older age population. It is characterized by cognitive impairment and dementia on the long term leading to a wide spectrum of social and financial burdens. Due to these burdens, there is a need to have a better understanding of the disease pathophysiology as well as to come up with more readily available and cost-effective screening tools to provide an acceptable estimate of the disease risk/diagnosis in the early years of the disease before dementia develops as it is in these early years that lifestyle modifications can be more effective in protecting against and delaying the frank cognitive impairment associated with AD. Recently, there has been a more detailed, yet incomplete, comprehension of the inflammatory component of the AD pathophysiology. The inflammatory response in AD entails hyperactivation of neutrophils with noticeable changes in their subsets and increased migration of lymphocytes into the central nervous system (CNS) across the compromised blood-brain barrier (BBB). These changes in the counts of the different immune cells in AD allowed for pursuing a new cost-effective, and more widely accessible diagnostic tool, which is the neutrophil-to-lymphocyte ratio (NLR). In this review, we aimed to discuss the inflammatory response in AD, and how this response is reflected in the counts of different immune cells, mainly neutrophils and lymphocytes which can be implemented in the utility of NLR as a diagnostic tool in AD patients.