Abstract Background Attention to the healthcare workforce has increased, yet comprehensive information on migrant healthcare workers is missing. This study focuses on migrant healthcare workers' experiences and mobility patterns in the middle of a global health crisis, aiming to explore the capacity for circular migration and support effective and equitable healthcare workforce policy. Methods Romanian physicians working in Germany during the COVID‐19 pandemic served as an empirical case study. We applied a qualitative explorative approach; interviews ( n = 21) were collected from mid of September to early November 2022 and content analysis was performed. Results and Discussion Migrant physicians showed strong resilience during the COVID‐19 crisis and rarely complained. Commitment to high professional standards and career development were major pull factors towards Germany, while perceptions of limited career choices, nepotism and corruption in Romania caused strong push mechanisms. We identified two major mobility patterns that may support circular migration policies: well‐integrated physicians with a wish to give something back to their home country, and mobile cosmopolitan physicians who flexibly balance career opportunities and personal/family interests. Health policy must establish systematic monitoring of the migrant healthcare workforce including actor‐centred approaches, support integration in destination countries as well as health system development in sending countries, and invest in evidence‐based circular migration policy.
Abstract Neuroimaging markers based on Magnetic Resonance Imaging (MRI) combined with various other measures (such as informative covariates, vascular risks, brain activity, neuropsychological test etc.,) might provide useful predictions of clinical outcomes during progression towards Alzheimer’s disease (AD). The Bayesian approach aims to provide a trade-off by employing relevant features combinations to build decision support systems in clinical settings where uncertainties are relevant. We tested the approach in the MRI data across 959 subjects, aged 59-89 years and 453 subjects with available neuropsychological test scores and CSF biomarker status (amyloid-beta ( Aβ )42/40 & and phosphorylated tau (pTau)) from a large sample multi-centric observational cohort (DELCODE). In order to explore the beneficial combinations of information from different sources, we presented a MRI-based predictive modelling of memory performance and CSF biomarker status (positive or negative) in the healthy ageing group as well as subjects at risk of Alzheimer’s disease using a Gaussian process multikernel framework. Furthermore, we systematically evaluated predictive combinations of input feature sets and their model variations, i.e. (A) combinations of brain tissue classes and feature type (modulated vs. unmodulated), choices of filter size of smoothing (ranging from 0 to 15 mm full width at half maximum), and image resolution (1mm, 2mm, 4mm and 8mm); (B) incorporating demography and covariates (C) the impact of the size of the training data set (i.e., number of subjects); (D) the influence of reducing the dimensions of data and (E) choice of kernel types. Finally, the approach was tested to reveal individual cognitive scores at follow-up (up to 4 years) using the baseline features. The highest accuracy for memory performance prediction was obtained for a combination of neuroimaging markers, demographics, genetic information (ApoE4) and CSF-biomarkers explaining 57% of outcome variance in out of sample predictions. The best accuracy for Aβ 42 / 40 status classification was achieved for combination demographics, ApoE4 and memory score while usage of structural MRI improved the classification of individual patient’s pTau status.
Abstract Background Neuroinflammation constitutes a pathological hallmark of Alzheimer’s disease (AD). Still, it remains unresolved if peripheral inflammatory markers can be utilized for research purposes similar to blood-based beta-amyloid and neurodegeneration measures. We investigated experimental inflammation markers in serum and analyzed interrelations towards AD pathology features in a cohort with a focus on at-risk stages of AD. Methods Data of 74 healthy controls (HC), 99 subjective cognitive decline (SCD), 75 mild cognitive impairment (MCI), 23 AD relatives, and 38 AD subjects were obtained from the DELCODE cohort. A panel of 20 serum biomarkers was determined using immunoassays. Analyses were adjusted for age, sex, APOE status, and body mass index and included correlations between serum and CSF marker levels and AD biomarker levels. Group-wise comparisons were based on screening diagnosis and routine AD biomarker-based schematics. Structural imaging data were combined into composite scores representing Braak stage regions and related to serum biomarker levels. The Preclinical Alzheimer’s Cognitive Composite (PACC5) score was used to test for associations between the biomarkers and cognitive performance. Results Each experimental marker displayed an individual profile of interrelations to AD biomarkers, imaging, or cognition features. Serum-soluble AXL (sAXL), IL-6, and YKL-40 showed the most striking associations. Soluble AXL was significantly elevated in AD subjects with pathological CSF beta-amyloid/tau profile and negatively related to structural imaging and cognitive function. Serum IL-6 was negatively correlated to structural measures of Braak regions, without associations to corresponding IL-6 CSF levels or other AD features. Serum YKL-40 correlated most consistently to CSF AD biomarker profiles and showed the strongest negative relations to structure, but none to cognitive outcomes. Conclusions Serum sAXL, IL-6, and YKL-40 relate to different AD features, including the degree of neuropathology and cognitive functioning. This may suggest that peripheral blood signatures correspond to specific stages of the disease. As serum markers did not reflect the corresponding CSF protein levels, our data highlight the need to interpret serum inflammatory markers depending on the respective protein’s specific biology and cellular origin. These marker-specific differences will have to be considered to further define and interpret blood-based inflammatory profiles for AD research.
Neuroinflammation plays a pivotal role in the pathogenesis of Alzheimer`s disease (AD). Brain macrophage populations differentially modulate the immune response to AD pathology according to the disease stage. Triggering receptor expressed on myeloid cells 2 (TREM2) is known to play a protective role in AD and has been postulated as a putative therapeutic target. Whether, and to which extent TREM2 expression can be modulated in the aged macrophage population of the brain is unknown, emphasizing the need for a human, patient-specific model. Using cells from AD patients and matched controls (CO) we designed an assay based on monocyte-derived macrophages to mimic brain-infiltrating macrophages and to assess the individualized TREM2 synthesis in vitro. We systematically assessed the effects of short-term (acute-2 days) and long-term (chronic-10 days) M1- (LPS), M2- (IL-10, IL-4, TGF-β), and M0- (vehicle) macrophage differentiation on TREM2 synthesis. Moreover, the effects of retinoic acid (RA), a putative TREM2 modulator, on individualized TREM2 synthesis were assessed. We report increased TREM2 synthesis after acute M2- compared to M1-differentiation in CO- but not AD-derived cells. Chronic M2- and M0-differentiation however resulted in an increase of TREM2 synthesis in both AD- and CO-derived cells while chronic M1-differentiation increased TREM2 in AD-derived cells only. Moreover, chronic M2- and M0-differentiation improved the amyloid-β (Aβ) uptake of the CO-derived whereas M1-differentiation of the AD-derived cells. Interestingly, RA-treatment did not modulate TREM2. In the age of personalized medicine, our individualized model could be used to screen for potential drug-mediated treatment responses in vitro. Triggering receptor expressed on myeloid cells 2 (TREM2) has been postulated as a putative therapeutic target in Alzheimer's disease (AD). Using cells from AD patients and matched controls (CO), we designed a monocyte-derived macrophages (Mo-MФs) assay to assess the individualized TREM2 synthesis in vitro. We report increased TREM2 synthesis after acute M2- compared to M1- macrophage differentiation in CO- but not AD-derived cells. Chronic M2- and M0- differentiation however resulted in an increase of TREM2 synthesis in both AD- and CO-derived cells while chronic M1-differentiation increased TREM2 in AD-cells only.
Accumulating evidence indicates the specific involvement of inflammatory processes in major depressive disorder (MDD), particularly affecting innate immunity. Most immune alterations have so far been determined based on plasma or cerebrospinal fluid cytokine levels. To precisely characterize putative innate immune-mediated mechanisms in MDD pathogenesis, we sought to disentangle "state" from "trait" effects in a patient-specific cell model by quantifying the impact of patient-derived autologous sera (AS) on patient-specific monocyte-derived macrophages (Mo-MФs) polarization in vitro. Mo-MФs were generated from 28 patients with moderate to severe MDD and 28 age-, sex-, smoking status- and BMI-matched healthy controls (HC). Cells were treated either with AS or fetal calf serum (FCS) and polarized into M1 (LPS), M2 (IL-10, IL-4, TGF-β) or M0 (unstimulated) macrophages. Polarization capacity was quantified by means of specific M1 (CCR7, CD86, CXCL10, IL-12p70, TNF-α, IL-6, IL-1β, IL-12p40, IL-23, IP-10) and M2 (CD206, IL-10, TARC, IL-1RA) markers. Compared to HC, significantly increased M1-polarization was observed for MDD patients in the presence of FCS, however, polarization in AS enriched media determined an increased M2-polarization in patients. Moreover, female MDD patients exhibited increased M1- and decreased M2-polarization in both conditions compared to male MDD patients. Our data suggests that Mo-MФs derived from patients with MDD exhibit facilitated M1-polarization under traditional cell culture conditions and an increased potential for M2-polarization when cultured in AS. Striking inter-individual variation and pronounced gender effects highlight the potential utility of our personalized cell model-based approach to aid diagnostic and therapeutic decisions.
Abstract Low-invasive biomarkers are urgently needed for the detection of molecular pathology in Frontotemporal Dementia (FTD), FTD spectrum disorders and Amyotrophic Lateral Sclerosis (ALS). This is particularly true in behavior variant FTD (bvFTD), in which premortem biomarkers are missing to distinguish underlying Tau from TAR DNA binding protein (TDP-43) pathology. This lack of biomarkers prevents the stratification of patients for intervention trials and constitutes a major obstacle for the development of disease-modifying therapies. Extracellular vesicles (EVs) have been implicated in neurodegenerative disease pathology, contributing to the release and potentially to intercellular transmission of pathologically aggregated proteins. Here, we show that plasma EVs contain quantifiable amounts of TDP-43 and full-length Tau, which allows the quantification of 3 repeat (3R) and 4 repeat (4R) Tau isoforms. Plasma EV TDP-43 levels and EV 3R/4R Tau ratios were determined in a pilot and validation study of 704 patients, including 37 genetic and 31 neuropathologically proven cases. Diagnostic groups comprised patients with the TDP-43 proteinopathy ALS, the 4R tauopathy Progressive Supranuclear Palsy (PSP), bvFTD as a group with either Tau or TDP-43 pathology, and healthy controls (HC). Compared to HC, plasma EV 3R/4R Tau ratios were decreased in PSP, unchanged in ALS, and increased in a subset of bvFTD patients, consistent with Tau pathology in approximately 40% of cases with bvFTD. EV Tau ratio discriminated between PSP and bvFTD, ALS and healthy controls (AUC 0.96-0.99), and between bvFTD and ALS (AUC 0.90) as well as HC (AUC 0.91). Plasma EV TDP-43 levels were increased in ALS and in those bvFTD patients who did not display high EV Tau ratios. Plasma EV TDP-43 discriminated patients with ALS from HC (AUC 0.99), bvFTD (AUC 0.91) and PSP (AUC 0.99). The combination of EV Tau ratio and EV TDP-43 was reliably able to discriminate between TDP-43 and Tau pathology in bvFTD. This blood-based classification was confirmed in genetic and autopsy proven cases. Both markers strongly correlated with the neurodegeneration marker neurofilament light chain (NfL) as well as with clinical and neuropsychological markers of disease severity in ALS (TDP-43 with ECAS, ALS-FRS-R), bvFTD (TDP-43 and Tau ratio with CDR-SB, CDR plus NACC FTLD) and PSP (Tau ratio with PSP-RS). Taken together, the combination of both markers may aid the molecular diagnosis of FTD, FTD spectrum disorders and ALS, the stratification of patients for therapeutic trials and bears the potential of a biomarker to monitor disease progression and target engagement.
Here, we investigated whether fractional anisotropy (FA) of hippocampus-relevant white-matter tracts mediates the association between baseline Mediterranean diet adherence (MeDiAd) and verbal episodic memory over four years. Participants were healthy older adults with and without subjective cognitive decline and patients with amnestic mild cognitive impairment from the DELCODE cohort study (n = 376; age: 71.47 ± 6.09 years; 48.7% female). MeDiAd and diffusion data were obtained at baseline. Verbal episodic memory was assessed at baseline and four yearly follow-ups. The associations between baseline MeDiAd and white matter, and verbal episodic memory's mean and rate of change over four years were tested with latent growth curve modeling. Baseline MeDiAd was associated with verbal episodic memory four years later (95% confidence interval, CI [0.01, 0.32]) but not with its rate of change over this period. Baseline Fornix FA mediated – and, thus, explained – that association (95% CI [0.002, 0.09]). Fornix FA may be an appropriate response biomarker of Mediterranean diet interventions on verbal memory in older adults.
