Search Results (163)

Neuroimmune interactions play a critical role in the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), with microglia acting as key mediators of neuroinflammation. Microglia exhibit dual roles, contributing to both neuroprotection and neurotoxicity depending on their activation state. In AD, amyloid-beta (Aβ) aggregation leads to chronic microglial activation, resulting in excessive pro-inflammatory cytokine release (e.g., TNF-α, IL-1β, IL-6), oxidative stress, and synaptic dysfunction. In PD, α-synuclein aggregation triggers a similar neuroinflammatory cascade, exacerbating dopaminergic neuronal loss in the substantia nigra. Beyond inflammatory responses, microglia regulate synaptic plasticity, phagocytose pathological proteins, and interact with peripheral immune cells, influencing disease progression. Emerging evidence suggests that genetic variants in genes such as TREM2, CD33, and HLA modulate microglial function, thereby altering susceptibility to neurodegeneration. Dysregulated microglial responses, characterized by impaired clearance of protein aggregates and prolonged neuroinflammation, further amplify neuronal damage. Therapeutic strategies targeting microglial activation are under investigation, aiming to balance neuroinflammatory responses and enhance clearance mechanisms. Small-molecule inhibitors, monoclonal antibodies, and modulators of innate immune pathways are being explored to mitigate microglia-driven pathology. Understanding the complex interplay between microglia and neurodegeneration could pave the way for precision medicine approaches, optimizing treatments based on individual immune profiles. Further research is essential to delineate microglial heterogeneity across disease stages and uncover novel targets for therapeutic intervention. Full article

Objectives: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis that can lead to severe neurological impairments, particularly in pediatric patients. Effective biomarkers for diagnosis and prognosis are crucial for improved treatment outcomes. To evaluate the potential of soluble Triggering Receptor Expressed on Myeloid cells 2 (sTREM2) in cerebrospinal fluid (CSF) and serum as diagnostic and prognostic biomarkers in pediatric patients with anti-NMDAR encephalitis. Methods: The study included 21 children diagnosed with anti-NMDAR encephalitis and 27 children with non-inflammatory neurological disorders (OND) as controls. CSF and serum samples were collected from each patient. sTREM2 levels were measured using enzyme-linked immunosorbent assay (ELISA). Statistical analyses, including Mann–Whitney U test and ROC curve analysis, were performed to assess the diagnostic and prognostic value of sTREM2. Results: sTREM2 levels in CSF and serum were significantly higher in children with anti-NMDAR encephalitis compared to the OND group (p < 0.001). CSF sTREM2 levels showed a positive correlation with modified Rankin Scale (mRS) scores and a negative correlation with Glasgow Coma Scale (GCS) scores, suggesting an association with disease severity. ROC curve analysis demonstrated that CSF sTREM2 had a high diagnostic accuracy (AUC = 0.887, p < 0.001), while serum sTREM2 showed a slightly lower diagnostic accuracy (AUC = 0.848, p < 0.001). Patients with better prognoses had significantly lower CSF sTREM2 levels than those with poorer outcomes (p = 0.029). Conclusions: Elevated CSF sTREM2 levels were associated with increased neuroinflammation and poorer clinical outcomes in children with anti-NMDAR encephalitis. These findings suggest that CSF sTREM2 may serve as a valuable biomarker for the diagnosis and prognosis of pediatric anti-NMDAR encephalitis. Full article

Cytokine and chemokine profiling is central to understanding inflammatory processes and the mechanisms driving diverse diseases. We introduce InCytokine, an open-source tool for semiquantitative analysis of cytokine and chemokine data generated by protein array technologies. InCytokine features robust and modular image-processing workflows, including automated spot detection, template alignment, normalization, quality control measures, and quantitative intensity summarization to deliver consistent and reliable readouts from profiling assays. We evaluated InCytokine by profiling wild-type microglia, TREM2 knockout, and Alzheimer’s disease-associated TREM2 R47H variant cells in response to lipopolysaccharide and sulfatide exposure. Differential expression analysis revealed unique sulfatide-specific and genotype-specific cytokine signatures in TREM2 variants. We also report an intriguing modulation of DPP4 and a divergent expression pattern of ENA-78 in TREM2 variants in response to lipopolysaccharide and sulfatide treatment. Such distinct expression signatures raise the possibility that TREM2 variants may play a role in modulating inflammatory signaling relevant to cardio-metabolic and Alzheimer’s disease. These signatures were corroborated using transcriptional profiling of the same microglia cells, revealing also a good concordance between protein array and RNA sequencing technologies. Taken together, InCytokine is an interactive, user-friendly web application for rapid, reproducible, and scalable analysis of protein array data, proven to generate meaningful insights for drug and biomarker discovery campaigns in pharmaceutical settings. Full article

In both Alzheimer’s disease (AD) patients and animal models, senile plaques are generally observed in the cerebral cortex rather than the cerebellum. The mechanisms underlying the regional resistance of the cerebellum to amyloid plaque deposition remain poorly understood. We investigated this cerebellar resistance using 5xFAD mice, an amyloidosis model with high expression of mutant human APP and PSEN1 in the cortex and cerebellum. In aged 5xFAD mice, the cerebellum had minimal amyloid-β (Aβ) deposition despite robust transgene expression, correlating with lower expression levels of IBA1, CD68, TREM2, and CD36 (although elevated expression of CD45 and MHC I) compared to the cortex. Consistent with the absence of plaques, cerebellar tissue lacked the dystrophic VGLUT1-positive synaptic accumulations prominent in the cortex. Cerebellar microglia maintained a distinct, less inflammatory phenotype yet displayed efficient clearance activity. Notably, ASC inflammasome specks—capable of seeding Aβ aggregation—were paradoxically more abundant in the cerebellum, implying that rapid Aβ clearance prevents these seeds from driving plaque formation. Furthermore, key extracellular matrix (ECM) proteoglycans brevican and aggrecan were elevated in the 5xFAD cerebellum. Cerebellar microglia showed enhanced internalization of brevican alongside small Aβ aggregates, exceeding that in cortical microglia. These findings indicate that region-specific microglial and ECM interactions—particularly efficient uptake and degradation of ECM–Aβ co-aggregates—may underlie the cerebellum’s resilience to amyloid plaque pathology. Full article

Background and Objectives: Sepsis is a life-threatening condition caused by a dysregulated host response to infection. Early recognition is crucial to improve outcomes, but conventional biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) show limited diagnostic accuracy. Materials and Methods: We performed a narrative review of the literature on sepsis biomarkers, with a focus on their biological role, diagnostic performance, clinical applicability, and limitations. Particular attention was given to presepsin (P-SEP) and monocyte distribution width (MDW), which have recently gained relevance. Results: Several novel biomarkers—including lipopolysaccharide-binding protein (LBP), soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), mid-regional pro-adrenomedullin (MR-proADM), neutrophil gelatinase-associated lipocalin (NGAL), Proenkephalin (PENK), and circulating microRNAs—have been studied, though most remain investigational. Among them, P-SEP shows rapid kinetics and correlation with disease severity, while MDW, derived from routine complete blood count, offers encouraging sensitivity and cost-effectiveness in emergency settings. Both biomarkers appear practical and potentially valuable for early sepsis detection. Conclusions: P-SEP and MDW emerge as the most promising biomarkers for timely sepsis recognition and risk stratification. Further validation and standardization are required to include them into routine clinical practice. Full article

The microglia, first identified by Pío del Río-Hortega, are resident macrophages in the CNS that aid in immune monitoring, synaptic remodeling, and tissue repair. Microglial biology’s dual functions in maintaining homeostasis and contributing to neurodegeneration are examined in this review, with a focus on neurodegenerative disease treatment targets. Methods: We reviewed microglial research using single-cell transcriptomics, molecular genetics, and neuroimmunology to analyze heterogeneity and activation states beyond the M1/M2 paradigm. Results: Microglia maintains homeostasis through phagocytosis, trophic factor production, and synaptic pruning. They acquire activated morphologies in pathological conditions, releasing proinflammatory cytokines and reactive oxygen species via NF-κB, MAPK, and NLRP3 signaling. Single-cell investigations show TREM2 and APOE-expressing disease-associated microglia (DAM) in neurodegenerative lesions. Microglial senescence, mitochondrial failure, and chronic inflammation result from Nrf2/Keap1 redox pathway malfunction in ageing. Microglial interactions with astrocytes via IL-1α, TNF-α, and C1q result in neurotoxic or neuroprotective A2 astrocytes, demonstrating linked glial responses. Microglial inflammatory or reparative responses are influenced by epigenetic and metabolic reprogramming, such as regulation of PGC-1α, SIRT1, and glycolytic flux. Microglia are essential to neuroprotection and neurodegeneration. TREM2 agonists, NLRP3 inhibitors, and epigenetic modulators can treat chronic neuroinflammation and restore CNS homeostasis in neurodegenerative illnesses by targeting microglial signaling pathways. Full article

M2-like tumor-associated macrophages (TAMs) are a promising target for cancer immunotherapy, particularly for cancer patients who are refractory to current immune checkpoint inhibitors (ICIs). Previously, we showed that prostaglandin E1 (PGE1) enhances the expression of M1 markers, including HLA-DR, on macrophages and induces the M1 polarization of TAMs in vivo. This study investigated the pharmacological mechanisms by which PGE1 and its derivatives suppress the expression of M2 markers, including TREM2 and CXCR2. Macrophages were cultured in ultralow attachment dishes either alone or in combination with liver cancer cell lines to generate homospheroids or heterospheroids. Cell surface marker expression was assessed by flow cytometry. Compared with homospheroids, M2 marker expression on macrophages in heterospheroids was significantly increased, suggesting that heterospheroid culture promotes M2 polarization. PGE1 decreased M2 marker expression in heterospheroids more effectively compared with PGE2, PGE3, misoprostol, and 13,14-dihydro-15-keto-PGE1, whereas the suppressive effects of 15-keto- and 13,14-dihydro-PGE1s, and lubiprostone were comparable to that of PGE1. Pharmacological inhibition of prostaglandin receptors revealed that EP2 and EP4 receptors are involved in the PGE1-induced reprogramming of M2-like macrophages to M1 macrophages. In summary, PGE1 and its derivatives are promising TAM-targeting immunotherapeutics. Full article

While genetics implicate a central role for dysregulated innate immunity in Alzheimer’s disease (AD), the contributions of peripheral myeloid cells, such as monocytes, have been largely overlooked in favor of microglia. Here, we investigate whether AD-associated loci, specifically rs3865444 in the CD33 locus and rs1057233 in the SPI1 locus, converge on shared functional pathways in monocytes in the context of amyloid-beta peptide 1-42 (Aβ1-42) as an immune stimulus. To do so, we isolated monocytes from peripheral blood mononuclear cells (PBMCs) from healthy individuals and exposed them to aggregated Aβ1-42. In this study, we identify functional convergence of the CD33 and SPI1 AD risk variants in the context of aggregated Aβ, both resulting in reduced phagocytosis and loss of surface TREM2 expression, demonstrating an interaction between genetics and environment to reduce myeloid cell fitness. These findings highlight that peripheral monocytes, like brain-resident microglia, are genetically and functionally linked to AD risk, underscoring their importance as accessible immune cells that contribute to disease susceptibility and progression. Full article

Astrocytes and microglia constitute nearly half of all central nervous system cells and are indispensable for its proper function. Both exhibit striking morphological and functional heterogeneity, adopting either neuroprotective (A2, M2) or proinflammatory (A1, M1) phenotypes in response to cytokines, pathogen-associated molecular patterns (PAMPs)/damage-associated molecular patterns (DAMPs), toll-like receptor 4 (TLR4) activation, and NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling. Crucially, many of these phenotypic transitions arise during the earliest stages of neurodegeneration, when glial dysfunction precedes overt neuronal loss and may act as a primary driver of disease onset. This review critically examines glial-centered hypotheses of neurodegeneration, with emphasis on their roles in early disease phases: (i) microglial polarization from an M2 neuroprotective state to an M1 proinflammatory state; (ii) NLRP3 inflammasome assembly via P2X purinergic receptor 7 (P2X7R)-mediated K⁺ efflux; (iii) a self-amplifying astrocyte–microglia–neuron inflammatory feedback loop; (iv) impaired microglial phagocytosis and extracellular-vesicle–mediated propagation of β-amyloid (Aβ) and tau; (v) astrocytic scar formation driven by aquaporin-4 (AQP4), matrix metalloproteinase-9 (MMP-9), glial fibrillary acidic protein (GFAP)/vimentin, connexins, and janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling; (vi) cellular reprogramming of astrocytes and NG2 glia into functional neurons; and (vii) mitochondrial dysfunction in glia, including Dynamin-related protein 1/Mitochondrial fission protein 1 (Drp1/Fis1) fission imbalance and dysregulation of the sirtuin 1/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Sirt1/PGC-1α) axis. Promising therapeutic strategies target pattern-recognition receptors (TLR4, NLRP3/caspase-1), cytokine modulators (interleukin-4 (IL-4), interleukin-10 (IL-10)), signaling cascades (JAK2–STAT, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), phosphoinositide 3-kinase–protein kinase B (PI3K–AKT), adenosine monophosphate-activated protein kinase (AMPK)), microglial receptors (triggering receptor expressed on myeloid cells 2 (TREM2)/spleen tyrosine kinase (SYK)/ DNAX-activating protein 10 (DAP10), siglec-3 (CD33), chemokine C-X3-C motif ligand 1/ CX3C motif chemokine receptor 1 (CX3CL1/CX3CR1), Cluster of Differentiation 200/ Cluster of Differentiation 200 receptor 1 (CD200/CD200R), P2X7R), and mitochondrial biogenesis pathways, with a focus on normalizing glial phenotypes rather than simply suppressing pathology. Interventions that restore neuroglial homeostasis at the earliest stages of disease may hold the greatest potential to delay or prevent progression. Given the complexity of glial phenotypes and molecular isoform diversity, a comprehensive, multitargeted approach is essential for mitigating Alzheimer’s disease and related neurodegenerative disorders. This review not only synthesizes pathogenesis but also highlights therapeutic opportunities, offering what we believe to be the first concise overview of the principal hypotheses implicating glial cells in neurodegeneration. Rather than focusing on isolated mechanisms, our goal is a holistic perspective—integrating diverse glial processes to enable comparison across interconnected pathological conditions. Full article

Neuroinflammation driven by microglial activation is a hallmark of Alzheimer’s disease (AD). Triggering receptor expressed on myeloid cells 2 (TREM2) is a key regulator of microglial inflammation, yet strategies to modulate its expression remain limited. Safflower leaves, a vegetable rich in flavonoids—particularly luteolin—were previously shown to attenuate neuroinflammation, reduce oxidative stress, and ameliorate cognitive impairment in APP/PS1 mice. Here, we demonstrated that safflower leaves inhibit microglial inflammation and upregulate TREM2 in APP/PS1 mice. Luteolin, the major active flavonoid in safflower leaves, exerted anti-inflammatory effects in lipopolysaccharides (LPS)-activated microglia. Mechanistically, luteolin enhanced Trem2 transcription by activating forkhead box protein O3 (FOXO3), a novel transcriptional regulator of Trem2 identified through promoter analysis. FOXO3 binding to the Trem2 promoter was essential for this regulation, and luteolin further promoted FOXO3 nuclear translocation. Crucially, Trem2 knockdown attenuated luteolin’s anti-inflammatory effects, confirming TREM2 as a key mediator. Overall, our study reveals the FOXO3-TREM2 axis as a potential therapeutic target for neuroinflammation and highlights luteolin present in safflower leaves as a candidate dietary intervention for AD, providing new mechanistic insights into the anti-inflammatory activity of this natural antioxidant. Full article

With the global rise in population aging, establishing effective strategies for the prevention and treatment of age-related neurodegenerative diseases, as well as their prodromal stage of cognitive frailty, has become an urgent challenge. Recent studies have revealed that the neural basis of both frailty and age-related disorders is closely associated with chronic neuroinflammation and impaired clearance of cellular debris, processes that are primarily regulated by microglia, the resident immune cells of the brain. As aging progresses, microglia exhibit reduced surveillance and motility, diminished phagocytic efficiency, and transition into a proinflammatory, hyperresponsive state. Such maladaptive microglia contribute to synaptic loss, white matter deterioration, and the spread of neurodegenerative pathology. Conversely, single-cell transcriptomic studies have identified distinct microglial subsets, including CD11c⁺ microglia, which show upregulation of lysosomal and lipid metabolism pathways, enhanced debris clearance, and elevated neurotrophic factor expression. These features suggest that certain microglial populations adopt protective or adaptive phenotypes that preserve neural integrity. However, under chronic inflammation or pathological conditions, even protective microglia may become inflammation-promoting. This review summarizes current evidence on microglial changes in aging, frailty, and neurodegeneration, emphasizing their dual roles and discussing strategies that modulate microglial function to maintain brain health and prevent or treat frailty and age-related diseases. Full article

Background/Objectives: TREM2 is a transmembrane receptor highly expressed in microglia and macrophages, and its involvement in Alzheimer’s disease, obesity, and cancer has garnered significant attention. Although its biological function has been actively investigated, the mechanisms by which its expression is regulated remain incompletely characterized. In this study, we aimed to identify transcription factors that modulate TREM2 expression among those reported to be expressed in microglia. Methods: We inserted a 5 kb upstream region of TREM2 into a luciferase reporter vector. This construct was co-expressed with 15 transcription factors, and the TREM2 transcriptional activity was evaluated using luciferase assays. The most promising transcription factor was subsequently knocked down in HMC3 cells, which are derived from human microglia, to assess its effect on endogenous TREM2 expression. Results: Among the 15 transcription factor candidates tested, SPI1 (PU.1), MAFB, CEBPA, ZEB2, and SALL1 most strongly enhanced TREM2 transcriptional activity. ZEB2 was prioritized due to its limited study in microglia and higher co-expression with TREM2. In HMC3 cells, ZEB2 knockdown reduced both TREM2 mRNA and protein levels. Further analysis using domain-deleted mutants of ZEB2 indicated that the zinc finger domains are essential for its transcriptional activity. Analysis using truncated mutants of the TREM2 upstream region suggests that ZEB2 acts on multiple sites within this region. Chromatin immunoprecipitation also suggested an interaction between ZEB2 and the upstream region of TREM2. Conclusions: This study novelly suggests ZEB2 as a transcription factor that promotes TREM2 expression. Further investigation into the role of ZEB2 in various TREM2-associated diseases is warranted. Full article

Background/Objectives: This study investigated clinical value of galectin-9 (Gal-9), a soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), and soluble CD25 (sCD25) among critically ill patients with organ failure in the emergency department. Methods: Overall, 786 patients were enrolled and classified into non-infectious organ failure (NIOF, n = 331), sepsis (n = 266), and septic shock (n = 189). The diagnostic value of Gal-9, sTREM-1, and sCD25 were evaluated by receiver operating characteristic curve analysis. The prognostic value of the biomarkers was evaluated using Kaplan–Meier survival curve and Cox proportional hazard model analyses. Results: Gal-9, sTREM-1, and sCD25 could discriminate sepsis from NIOF (Gal-9, area under the curve [AUC], 0.599–0.678; sTREM-1, AUC, 0.616–0.695; sCD25, AUC, 0.710–0.781) and septic shock from sepsis (Gal-9, AUC, 0.562–0.667; sTREM-1, AUC, 0.572–0.676; sCD25, AUC, 0.555–0.660), respectively. Sepsis patients with higher levels of biomarkers over their cut-off value showed higher 30-day mortality compared to those with lower levels below the cut-off value (Gal-9 ≥ 14,391.80 ng/L, p < 0.001; sTREM-1 ≥ 580.62 ng/L, p < 0.001; sCD25 ≥ 1639.29 ng/L, p < 0.001; respectively) (log-rank test). sCD25 is an independent risk factor for 30-day mortality in patients with sepsis or septic shock. Conclusions: Gal-9, sTREM-1, and sCD25 showed diagnostic and prognostic value in critically ill patients with organ failure. sCD25 can predict the 30-day mortality in patients with sepsis. Gal-9, sTREM-1, and sCD25 could serve as auxiliary biomarkers to support clinicians in effective sepsis management. Full article

Background: Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection and remains a major cause of mortality in intensive care units. Methods: We analyzed plasma levels of sTREM-1, CRP, PCT, sCD14-ST, HMGB1, IL-6, IL-10, vitamin D (VD), and sHLA-G in patients with SIRS/sepsis, and assessed their relationships with APACHE II, SOFA scores, and survival. Results: Septic patients showed significantly elevated sTREM-1, CRP, PCT, sCD14-ST, and higher neutrophil-to-lymphocyte ratio, while VD levels were markedly reduced. Logistic regression identified CRP and PCT as the strongest univariate predictors of sepsis, but after adjustment for age, sex, BMI, and comorbidities, CRP lost significance, whereas VD and sCD14-ST remained independent predictors. Prognostically, higher IL-10 levels significantly correlated with 7- and 28-day mortality and with SOFA scores, while higher VD concentrations predicted better survival. Conclusion: CRP, PCT, and sCD14-ST are reliable diagnostic biomarkers of sepsis, with sTREM-1 providing additional value for disease monitoring. After adjustment for clinical covariates, VD emerged as an independent protective factor, whereas elevated IL-10 significantly predicted 7- and 28-day mortality. These findings underscore the utility of combining inflammatory and immunoregulatory biomarkers to improve sepsis diagnostics and prognostication, warranting validation in larger multicenter cohorts. Full article

Rotavirus (RV) is one of the main etiologic agents associated with diarrheal diseases (DDs), being responsible for approximately 200 thousand deaths annually. Currently, there are still many aspects regarding the virus biology, cell cycle, and pathophysiology of RV that need further elucidation. Therefore, the present work aimed to investigate whether the triggering receptor expressed on myeloid cells 1 (TREM-1) might be associated with RV infection. This immune receptor has been observed as an amplifier of inflammatory responses in different infectious and non-infectious diseases, including inflammatory bowel disease and celiac disease. Initially, we searched for public transcriptomic data regarding RV infection and the expression of TREM-1 and its associated genes, which were significantly upregulated in infected mice and children. Then, we infected monocytes with the virus, with or without a TREM-1 inhibitor. The inhibition of the receptor’s activity resulted in a significant decrease in IL-1β production. We also observed a reduction in cytopathic effects when MA104 cells were treated with TREM-1 inhibitors and then infected with simian RV. To further elucidate the interactions between the virus and TREM-1, in silico tools were used to simulate interactions between the receptor and RV proteins. These simulations suggested the occurrence of interactions between TREM-1 and VP5*, a protein involved in viral attachment to target cells, and also between the receptor and NSP4, a viral enterotoxin with immunostimulant properties. Hence, our results indicate that TREM-1 is involved in RV infection, both as a mediator of inflammatory responses and as a player in the host–virus relationship. Full article