Influence of Allergy on Immunoglobulins and Amyloid-β in the Cerebrospinal Fluid of Patients with Alzheimer's Disease

AllergoOncology: Biomarkers and refined classification for research in the allergy and glioma nexus-A joint EAACI-EANO position paper

Epidemiological studies have explored the relationship between allergic diseases and cancer risk or prognosis in AllergoOncology. Some studies suggest an inverse association, but uncertainties remain, including in IgE-mediated diseases and glioma. Allergic disease stems from a Th2-biased immune response to allergens in predisposed atopic individuals. Allergic disorders vary in phenotype, genotype and endotype, affecting their pathophysiology. Beyond clinical manifestation and commonly used clinical markers, there is ongoing research to identify novel biomarkers for allergy diagnosis, monitoring, severity assessment and treatment. Gliomas, the most common and diverse brain tumours, have in parallel undergone changes in classification over time, with specific molecular biomarkers defining glioma subtypes. Gliomas exhibit a complex tumour-immune interphase and distinct immune microenvironment features. Immunotherapy and targeted therapy hold promise for primary brain tumour treatment, but require more specific and effective approaches. Animal studies indicate allergic airway inflammation may delay glioma progression. This collaborative European Academy of Allergy and Clinical Immunology (EAACI) and European Association of Neuro-Oncology (EANO) Position Paper summarizes recent advances and emerging biomarkers for refined allergy and adult-type diffuse glioma classification to inform future epidemiological and clinical studies. Future research is needed to enhance our understanding of immune-glioma interactions to ultimately improve patient prognosis and survival.

Causal Association Between Allergic Diseases and Dementia: Evidence from Multivariate Mendelian Randomization Study

Background

The link between allergic diseases and dementia remains controversial, and the genetic causality of this link is unclear.

Objective

This study investigated the causal relationship between allergic diseases and dementia using univariate and multivariate Mendelian randomization (MR) methods.

Methods

We selected genome-wide association studies including 66,645 patients with allergic diseases and 12,281 patients with dementia, with statistical datasets derived from the FinnGen Consortium of European origin. After a rigorous screening process for single nucleotide polymorphisms to eliminate confounding effects, MR estimation was performed mainly using the inverse variance weighting method and the MR-Egger method. Sensitivity analyses were performed using Cochran's Q test, MR-PRESSO test, MR Pleiotropy residuals and leave-one-out analysis.

Results

Univariate and multivariate MR together demonstrated a causal relationship between atopic dermatitis and reduced vascular dementia (VaD) risk (OR = 0.89, 95% CI: 0.81-0.99, p = 0.031; OR = 0.85, 95% CI: 0.76-0.95, p = 0.003). MVMR confirmed asthma was associated with a reduction in the risk of Alzheimer's disease (AD) (OR = 0.82, 95% CI: 0.71-0.94, p = 0.005) and may be associated with a reduction in the risk of VaD (OR = 0.80, 95% CI: 0.65-0.99, p = 0.042); allergic rhinitis may be causally associated with an increased risk of AD (OR = 1.16, 95% CI: 1.00-1.35, p = 0.046) and VaD (OR = 1.29, 95% CI: 1.03-1.62, p = 0.027). In sensitivity analyses, these findings were reliable.

Conclusions

MR methods have only demonstrated that allergic rhinitis dementia is associated with an increased risk of developing dementia. Previously observed associations between other allergic diseases and dementia may be influenced by comorbidities and confounding factors rather than causality.

Amyloid Beta Peptides Lead to Mast Cell Activation in a Novel 3D Hydrogel Model

Alzheimer's disease (AD) is a prevalent neurodegenerative disease and the world's primary cause of dementia among the elderly population. The aggregation of toxic amyloid-beta (Aβ) is one of the main pathological hallmarks of the AD brain. Recently, neuroinflammation has been recognized as one of the major features of AD, which involves a network of interactions between immune cells. The mast cell (MC) is an innate immune cell type known to serve as a first responder to pathological changes and crosstalk with microglia and neurons. Although an increased number of mast cells were found near the sites of Aβ deposition, how mast cells are activated in AD is not clear. We developed a 3D culture system to culture MCs and investigated the activation of MCs by Aβ peptides. Because collagen I is the major component of extracellular matrix (ECM) in the brain, we encapsulated human LADR MCs in gels formed by collagen I. We found that 3D-cultured MCs survived and proliferated at the same level as MCs in suspension. Additionally, they can be induced to secrete inflammatory cytokines as well as MC proteases tryptase and chymase by typical MC activators interleukin 33 (IL-33) and IgE/anti-IgE. Culturing with peptides Aβ1-42, Aβ1-40, and Aβ25-35 caused MCs to secrete inflammatory mediators, with Aβ1-42 inducing the maximum level of activation. These data indicate that MCs respond to amyloid deposition to elicit inflammatory responses and demonstrate the validity of collagen gel as a model system to investigate MCs in a 3D environment to understand neuroinflammation in AD.

Chronic cough, not asthma, is associated with depression in the elderly: a community-based population analysis in South Korea

BACKGROUND/AIMS

Depression and allergic diseases, including asthma, are frequently reported as comorbid conditions. However, their associations have been rarely examined in community-based elderly populations.

METHODS

The analyses were performed using the baseline data set of the Korean Longitudinal Study of Health and Aging, which consists of 1,000 elderly participants (aged > 65 years) randomly recruited from an urban community. Depression was assessed using the Geriatric Depression Scale, Center for Epidemiologic Studies Depression Scale, and Hamilton Rating Scale for Depression. Major and minor depressive disorders were diagnosed by psychiatrists. Allergic conditions were assessed using structured questionnaires, lung function, and skin prick test. Quality of life and comorbidities were assessed using structured questionnaires.

RESULTS

Prevalence of asthma and major depressive disorder were 5.4% and 5.3%, respectively. The rate of depression was not significantly different between the non-asthmatic and asthmatic groups. No correlation was observed between the scores obtained using the depression scales and self-reported asthma. However, chronic, frequent, and nocturnal cough were significantly associated with depression and scores obtained using the depression scales, which remained significant in multivariate logistic regression analyses (chronic cough: odds ratio [OR], 3.23; 95% confidence interval [CI], 2.57 to 12.74; p = 0.04). Rhinitis was independently associated with high Mini-Mental State Examination scores (OR, 1.11; 95% CI, 1.05 to 1.17; p < 0.001) and low 36-item short-form (OR, 0.96; 95% CI, 0.80 to 0.98; p = 0.002).

CONCLUSION

Depression may not be significantly associated with asthma and allergic diseases in elderly populations, but cough is a significant factor affecting depression.

Influence of PM2.5 Exposure Level on the Association between Alzheimer's Disease and Allergic Rhinitis: A National Population-Based Cohort Study

Alzheimer's disease (AD) is an irreversible neurodegenerative disease that leads to dementia, health impairment, and high economic cost. Allergic rhinitis (AR) is a chronic inflammatory and allergic disease of the respiratory system that leads to health problems and has major effects on the daily lives of patients and their caregivers. Particulate matter (PM) refers to air pollutants 2.5 μm or less in diameter that are a source of concern because of their role in numerous diseases, including AR and other neurodegenerative diseases. To date, no study has demonstrated how PM_2.5 exacerbates AR and results in AD. We conducted a national population-based cohort study by obtaining patient data from the National Health Insurance Research Database of Taiwan for the 2008-2013 period. PM_2.5 concentration data were obtained from the ambient air quality monitoring network established by the Environmental Protection Administration of Taiwan. Monthly PM_2.5 exposure levels were categorized into quartiles from Q1-Q4. The Cox proportional hazards analysis, after adjusting for age, sex, low income, and urbanization level, revealed that patients with AR had an elevated risk of developing AD (hazard ratio (HR): 2.008). In addition, the cumulative incidence of AD in the AR group was significantly higher than in the comparison group. The PM_2.5 levels at Q2-Q4 (crude HR: 1.663-8.315; adjusted HR: 1.812-8.981) were stratified on the basis of the PM_2.5 exposure group and revealed that AR patients exposed to PM_2.5 are significantly prone to develop AD. In addition, the logistic regression analyses, after adjustment, demonstrated that an increase in the PM_2.5 exposure level at Q2-Q4 (adjusted odds ratio (OR): 2.656-5.604) increased the risk of AR in AD patients. In conclusion, an increased PM_2.5 exposure level could be correlated with AR, which could in turn cause AD. AR increased the risk of AD, in which exposure to PM_2.5 increases the higher probability of AD.

Research progress on the roles of microRNAs in governing synaptic plasticity, learning and memory

The importance of non-coding RNA involved in biological processes has become apparent in recent years and the mechanism of transcriptional regulation has also been identified. MicroRNAs (miRNAs) represent a class of small regulatory non-coding RNAs of 22bp in length that mediate gene silencing by identifying specific sequences in the target messenger RNAs (mRNAs). Many miRNAs are highly expressed in the central nervous system in a spatially and temporally controlled manner in normal physiology, as well as in certain pathological conditions. There is growing evidence that a considerable number of specific miRNAs play important roles in synaptic plasticity, learning and memory function. In addition, the dysfunction of these molecules may also contribute to the etiology of several neurodegenerative diseases. Here we provide an overview of the current literatures, which support non-coding RNA-mediated gene function regulation represents an important but underappreciated, layer of epigenetic control that facilitates learning and memory functions.

Allergy Enhances Neurogenesis and Modulates Microglial Activation in the Hippocampus

Allergies and their characteristic T_H2-polarized inflammatory reactions affect a substantial part of the population. Since there is increasing evidence that the immune system modulates plasticity and function of the central nervous system (CNS), we investigated the effects of allergic lung inflammation on the hippocampus—a region of cellular plasticity in the adult brain. The focus of the present study was on microglia, the resident immune cells of the CNS, and on hippocampal neurogenesis, i.e., the generation of new neurons. C57BL/6 mice were sensitized with a clinically relevant allergen derived from timothy grass pollen (Phl p 5). As expected, allergic sensitization induced high serum levels of allergen-specific immunoglobulins (IgG1 and IgE) and of T_H2 cytokines (IL-5 and IL-13). Surprisingly, fewer Iba1⁺ microglia were found in the granular layer (GL) and subgranular zone (SGZ) of the hippocampal dentate gyrus and also the number of Iba1⁺MHCII⁺ cells was lower, indicating a reduced microglial surveillance and activation in the hippocampus of allergic mice. Neurogenesis was analyzed by labeling of proliferating cells with bromodeoxyuridine (BrdU) and determining their fate 4 weeks later, and by quantitative analysis of young immature neurons, i.e., cells expressing doublecortin (DCX). The number of DCX⁺ cells was clearly increased in the allergy animals. Moreover, there were more BrdU⁺ cells present in the hippocampus of allergic mice, and these newly born cells had differentiated into neurons as indicated by a higher number of BrdU⁺NeuN⁺ cells. In summary, allergy led to a reduced microglia presence and activity and to an elevated level of neurogenesis in the hippocampus. This effect was apparently specific to the hippocampus, as we did not observe these alterations in the subventricular zone (SVZ)/olfactory bulb (OB) system, also a region of high cellular plasticity and adult neurogenesis.

Type 2 diabetes mellitus might be a risk factor for mild cognitive impairment progressing to Alzheimer's disease

BACKGROUND

Mild cognitive impairment (MCI) is the prodromal stage of Alzheimer's disease (AD), so identification of the related risk factors can be helpful. Although the association between type 2 diabetes mellitus (T2DM) and these modest changes in cognition is well established, whether T2DM will promote the transformation of MCI into AD is not a unified conclusion.

OBJECTIVE

This study aims to explore the relationship between T2DM and MCI in the elderly population living in the community in Shanghai, People's Republic of China.

METHODS

A total of 197 participants were included in the study. They were screened for T2DM, hyperlipidemia, traumatic brain injury, and family history of dementia. The Mini-Mental State Examination and the Montreal Cognitive Assessment were used to assess cognitive function. The diagnosis of AD was made according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, whereas the diagnosis of MCI was made according to Petersen's criteria. Then, we investigated the relation between T2DM and MCI.

RESULTS

A total of 82 (41.6%) participants had no cognitive impairment, 82 (41.6%) participants had MCI, and 33 (16.8%) participants had AD. Multivariate logistic regression models demonstrated that T2DM was a risk factor for AD (odds ratio =49.723, 95% CI =21.173-111.987).

CONCLUSION

T2DM might be a risk factor for MCI progressing into AD.