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Neuroinflammation plays a key role in Alzheimer's disease (AD), but the actions of microglial mediators may vary across stages of amyloid-beta (A beta) pathology. While drugs targeting brain immune responses are advancing to clinical trials, biomarkers to monitor their effects are lacking. This study investigated proteins expressed by activated microglia in three mouse models of A beta pathology and alpha-synuclein, both during disease progression and after treatment, to evaluate their potential as in vivo biomarkers. Immunofluorescent staining was performed on cortical sections from AppNL-G-F, tg-ArcSwe, and wild-type (WT) mice. TREM2, Axl, galectin-3, A beta, and cytokines were measured by immunoassays in brain homogenates from WT, AppNL-G-F, tg-ArcSwe, and tg-UppSwe mice across four age groups and from mice subjected to three treatment strategies targeting A beta (beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitor NB-360 and antibody RmAb158) or alpha-synuclein (antibody RmAb38E2). TREM2 and Axl colocalized with Iba1 and A beta in AppNL-G-F and tg-ArcSwe mice, with age-dependent increases observed in both models but not in tg-UppSwe. The lectin galectin-3 increased with age across all genotypes, including WT. A beta correlated with elevated TREM2, Axl, and Galectin-3. Two months of BACE1-inhibition reduced TREM2, Axl, and galectin-3 in tg-ArcSwe mice and TREM2 and Axl in AppNL-G-F mice. In summary, microglial TREM2, Axl, and galectin-3 are promising biomarkers for tracking AD-related neuroinflammation. Microglial interactions with A beta likely influence the outcomes of A beta-targeting therapies, and characterizing their dynamic states will inform the development of diagnostic tools and treatments relying on microglial activation to alleviate pathologies associated with neurodegenerative diseases.

The emerging class of bispecific antibodies represents a significant advancement in Alzheimer's disease (AD) immunotherapy by addressing the limited brain concentrations achieved with conventional monoclonal antibodies. The majority of bispecific antibodies developed for AD treatment utilize transferrin receptor (TfR1)-mediated transcytosis to enhance blood-brain barrier (BBB) penetration, resulting in higher and more uniform brain concentrations compared to conventional antibodies. This improved delivery has demonstrated superior efficacy in reducing brain amyloid-beta (A beta) burden. Additionally, TfR1-mediated delivery may help mitigate adverse effects such as amyloid-related imaging abnormalities (ARIA). This is likely achieved by a reduction in antibody accumulation at vascular A beta deposits, resulting from the combined effects of lower dosing and a different brain entry route when using bispecific antibodies. Besides targeting A beta, bispecific antibodies have been engineered to address other key pathological features of AD, including tau pathology and neuroinflammatory targets, which are critical drivers of disease progression. These antibodies also show promise in diagnostic applications, particularly as radioligands for antibody-based positron emission tomography (immunoPET), leveraging their rapid brain delivery and efficient and specific target engagement. Moreover, the principles of bispecific antibody technology have been adapted for use beyond immunotherapy. The incorporation of TfR1-binding domains into enzymes, antisense oligonucleotides, or viral vectors such as adeno-associated viruses broadens their therapeutic potential. These approaches may enable more efficient treatment strategies, not only for AD but also for other neurological disorders, by facilitating the delivery of diverse therapeutic agents across the BBB.

Background

Transferrin receptor (TfR)-mediated transcytosis is a well-established method for delivering biologic therapeutics and diagnostics to the brain. Although moderate affinity towards TfR is beneficial for TfR-mediated brain delivery at therapeutic doses, emerging evidence has indicated that high TfR affinity may be more beneficial at tracer doses. With the development of antibody-based PET radioligands for neurodegenerative diseases, such as Alzheimer's disease, understanding the pharmacokinetics of TfR-binders at tracer dose is essential. Thus, this study aimed to evaluate the effect of TfR affinity on brain uptake at a tracer dose in both wild-type (WT) and amyloid-beta (A beta) pathology presenting mice and to demonstrate the usability of TfR-mediated brain delivery of immunoPET diagnostic radioligands to visualize intrabrain A beta pathology in vivo.

Methods

Three different affinity variants of anti-mouse TfR-binding antibody 8D3, engineered by alanine point mutations, were selected. Bispecific antibodies were designed with knob-into-hole technology with one arm targeting TfR (8D3) and the other arm targeting human A beta (bapineuzumab). Antibody affinities were measured in an in vitro cell assay. In vivo pharmacokinetic analyses of radioiodinated bispecific antibodies and bapineuzumab in brain, blood and peripheral organs were performed over 7 days post-injection in WT mice and a model of A beta pathology (AppNL-G-F). The strongest TfR affinity bispecific antibody was also evaluated as a positron emission tomography (PET) radioligand for detecting A beta pathology in WT and AppNL-G-F mice.ResultsThe three bispecific antibodies bound to TfR with affinities of 10 nM, 20 nM and 240 nM. Independent of genotype, stronger TfR-affinity resulted in higher initial brain uptake. The two higher-affinity bispecific antibodies behaved similarly and differentiated between WT and AppNL-G-F mice earlier than the lowest affinity variant. Finally, the 10 nM bispecific antibody was able to clearly differentiate between WT and AppNL-G-F mice when used as a PET radioligand.

Conclusion

This study supports the hypothesis that stronger TfR affinity enhances brain uptake at a tracer dose. With the more effective detection of A beta pathology, stronger TfR affinity is a crucial design feature for future bispecific immunoPET radioligands for intrabrain targets via TfR-mediated transcytosis.

Purpose: The triggering receptor expressed on myeloid cells 2 (TREM2) has become a promising target for biologics in both monitoring and treating neuroinflammation in Alzheimer's disease (AD). This study aimed to develop and compare bispecific anti-TREM2 antibodies featuring different transferrin receptor (TfR) binders to enhance brain delivery, identifying the most suitable format for in vivo PET imaging of TREM2 in transgenic AD mice.

Methods: Three bispecific TREM2-antibody formats were produced and evaluated for their ability to cross the blood-brain barrier (BBB) via TfR-mediated transcytosis and bind TREM2. Blood concentration profiles up to 72 h post-injection (p.i.), and ex vivo brain uptake of iodine-125-labeled antibody constructs were quantified in App^NL-G-F and age-matched wild type (WT) mice using a γ-counter. The best-performing bispecific TREM2-antibody was radiolabeled with iodine-124 and used for in vivo PET imaging of brain TREM2 levels in App^NL-G-F mice at 72 h p.i. Brain TREM2 concentrations were subsequently quantified using ELISA.

Results: The antibody format carrying two scFv8D3 TfR-binders (IgG-scFv₂), demonstrated the highest brain concentrations of all tested bispecific constructs. This antibody also exhibited significantly higher brain concentrations in App^NL-G-F mice compared to WT mice at both 48 and 72 h p.i. This difference was further visualized and quantified through in vivo PET imaging. Moreover, brain concentrations of the antibody ligand correlated with elevated TREM2 levels in brain homogenates.

Conclusion: These findings highlight IgG-scFv₂ as a promising radioligand for in vivo PET imaging of TREM2, advancing non-invasive neuroinflammation studies and supporting drug development for AD and other neurodegenerative diseases.

The elimination of amyloid-beta (Aβ) plaques in Alzheimer's disease patients after treatment with anti-Aβ antibodies such as lecanemab and aducanumab is supported by a substantially decreased signal in amyloid positron emission tomography (PET) imaging. However, this decreased PET signal has not been matched by a similar substantial effect on cognitive function. There may be several reasons for this, including short treatment duration and advanced disease stages among the patients. However, one aspect that has not been investigated, and the subject of this study, is whether antibody engagement with amyloid plaques inhibits the binding of amyloid-PET ligands, leading to a false impression of Aβ removal from the brain. In the present study, tg-ArcSwe mice received three injections of RmAb158, the murine version of lecanemab or phosphate-buffered saline (PBS) before the administration of the amyloid-PET radioligand [11C]PiB, followed by isolation of brain tissue. Autoradiography showed that RmAb158- and PBS-treated mice displayed similar [11C]PiB binding. Moreover, the total Aβ1–40 levels, representing the major Aβ species of plaques in the tg-ArcSwe model, as well as soluble triggering receptor on myeloid cells 2 (sTREM2) levels, were similar in both groups. Interestingly, the concentration of soluble Aβ aggregates was decreased in the RmAb158-treated group, along with a small but significant decrease in the total Aβ1–42 levels. In conclusion, this study indicates that the binding of [11C]PiB to Aβ accurately mirrors the load of Aβ plaques in the brain, aligning with how amyloid-PET is interpreted in clinical studies of anti-Aβ antibodies. However, early treatment effects on soluble Aβ aggregates and Aβ1–42 levels were not detected. 

Background: Migraine and depression are two of the most common and debilitating conditions. From a clinical perspective, they are mostly prevalent in women and manifest a partial overlapping symptomatology. Despite the high level of comorbidity, previous studies hardly investigated possible common patterns in brain volumetric differences compared to healthy subjects. Therefore, the current study investigates and compares the volumetric difference patterns in sub-cortical regions between participants with migraine or depression in comparison to healthy controls.

Methods: The study included data from 43 930 participants of the large UK Biobank cohort. Using official ICD10 diagnosis, we selected 712 participants with migraine, 1 853 with depression and 23 942 healthy controls. We estimated mean volumetric difference between the groups for the different sub-cortical brain regions using generalized linear regression models, conditioning the model within the levels of BMI, age, sex, ethnical background, diastolic blood pressure, current tobacco smoking, alcohol intake frequency, Assessment Centre, Indices of Multiple Deprivation, comorbidities and total brain volume.

Results: We detected larger overall volume of the caudate (mean difference: 66, 95% CI [-3, 135]) and of the thalamus (mean difference: 103 mm(3), 95% CI [-2, 208]) in migraineurs than healthy controls. We also observed that individuals with depression appear to have also larger overall (mean difference: 47 mm(3), 95% CI [-7, 100]) and gray matter (mean difference: 49 mm(3), 95% CI [2, 95]) putamen volumes than healthy controls, as well as larger amygdala volume (mean difference: 17 mm(3), 95% CI [-7, 40]).

Conclusion: Migraineurs manifested larger overall volumes at the level of the nucleus caudate and of the thalamus, which might imply abnormal pain modulation and increased migraine susceptibility. Larger amygdala and putamen volumes in participants with depression than controls might be due to increased neuronal activity in these regions.

Low job satisfaction has been associated with both negative health and negative organizational outcomes. Knowledge on which factors influence job satisfaction remains limited. This study assesses the associations between job satisfaction and three personality traits related to cognitive- and inhibitory control: delay discounting, risk-taking and sensation seeking (DRS-traits). Delay discounting and sensation seeking were inferred using self-reported behavioral data and health measurements for 80,676 participants in the UK Biobank. Multiple linear regression analysis produced beta coefficients and confidence intervals for each DRS-trait and job satisfaction. Analyses were adjusted for age, socioeconomic status and sleep quality. A combination of the three DRS-traits (CDRS) was assessed as well. Delay discounting and risk-taking were associated with, respectively, lower and higher job satisfaction in both sexes. Sensation seeking had no significant association with job satisfaction for either sex. The combined score, CDRS, was only negatively associated with job satisfaction in females but not in males. We discuss that the negative association between delay discounting and job satisfaction may be due to career related delay discounting effects, but also highlight that low job satisfaction itself may also lead to increased delay discounting. Additionally, we discuss why increased risk-taking behavior may have a positive effect on job satisfaction.

Background: There is a growing interest in how personality may be related to the risk of developing disease. Associations between personality and stroke have so far only been studied in relation to stroke mortality. However, many stroke survivors suffer severe impairment of quality of life due to sequelae such as aphasia, hemiparesis, depression and anxiety. In this study we assess the association between personality and risk of stroke, regardless of mortality. Methods: Using self-reported data on psychological factors, mental health and social support, proxies for the Big Five personality traits were developed for 482,535 participants in the UK Biobank. Logistic regression and Cox proportional hazard models, with 95% confidence intervals (CI), were used to estimate odds ratios (OR) and hazard ratios (HR) between each personality trait and stroke prevalence (N = 6793) and incidence (N = 3312), respectively. Models were adjusted for demographic, health-related, and lifestyle factors. Results: Diligence and sociability were associated with a lower risk of stroke incidence in the fully adjusted model (respectively: [HR = 0.92; 95% CI = (0.88, 0.96)], [HR = 0.93; 95% CI = (0.89, 0.97)]). However, nervousness, curiosity and warmth were not significantly associated with a risk of stroke incidence. Conclusions: Individuals with higher levels of diligence and sociability may be at a reduced risk of developing stroke. With respect to the debated role of neuroticism in relation to cardiovascular disease, we did not find evidence of an association between nervousness and risk of developing stroke.

Compounds that contain (R)-3-amino-4-(2,4,5-trifluorophenyl)butanoic acid substituted with bicyclic amino moiety (2-aza-bicyclo[2.2.1]heptane) were designed using molecular modelling methods, synthesised, and found to be potent DPP-4 (dipeptidyl peptidase-4) inhibitors. Compound 12a (IC50 = 16.8 +/- 2.2 nM), named neogliptin, is a more potent DPP-4 inhibitor than vildagliptin and sitagliptin. Neogliptin interacts with key DPP-4 residues in the active site and has pharmacophore parameters similar to vildagliptin and sitagliptin. It was found to have a low cardiotoxic effect compared to sitagliptin, and it is superior to vildagliptin in terms of ADME properties. Moreover, compound 12a is stable in aqueous solutions due to its low intramolecular cyclisation potential. These findings suggest that compound 12a has unique properties and can act as a template for further type 2 diabetes mellitus drug development.

There is a growing interest in the psychiatric properties of the dissociative anaesthetic ketamine, as single doses have been shown to have fast-acting mood-enhancing and anxiolytic effects, which persist for up to a week after the main psychoactive symptoms have diminished. Therefore, ketamine poses potential beneficial effects in patients with refractory anxiety disorders, where other conventional anxiolytics have been ineffective. Ketamine is a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) glutamate receptor, which underlies its induction of pain relief and anaesthesia. However, the role of NMDA receptors in anxiety reduction is still relatively unknown. To fill this paucity in the literature, this systematic review assesses the evidence that ketamine significantly reduces refractory anxiety and discusses to what extent this may be mediated by NMDA receptor antagonism and other receptors. We highlight the temporary nature of the anxiolytic effects and discuss the high discrepancy among the study designs regarding many fundamental factors such as administration routes, complementary treatments and other treatments.