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SummaryPrevious studies have highlighted that spermidine has the ability to trigger the important process of dissolving amyloid-beta plaques by autophagy. This manuscript focuses on the correlation of serum spermidine levels between age and between performance in mini-mental state examinations. It will serve as a premise for an ongoing multicentric placebo-controlled study, which focuses on the effect of oral spermidine supplementation on memory performance. Memory tests were carried out on 80 subjects aged 60–96 years old in 6 nursing homes in Styria. Blood samples were taken for the determination of spermidine concentration. The results showed a significant correlation between the spermidine concentration and the mini-mental state examination score (p = 0.025). On the basis of the dependence demonstrated it can be concluded that spermidine might be suitable as a biomarker for the diagnosis of neurocognitive changes (senile dementia or Alzheimer’s disease).

In this study, levels of inflammatory protein biomarkers in venous plasma, plasma derived from capillary blood from the earlobe, and capillary plasma stored as dried plasma spots (DPS) were compared. Samples from 12 male individuals were assessed with a panel of 92 inflammation-related proteins using multiplex proximity extension assay. Correlations between sample types varied greatly between analytes. A high correlation of rho > 0.8 was observed between capillary plasma and DPS for 32 analytes. At this level of correlation, 13 analytes correlated between venous and capillary plasma and 5 analytes in the comparison of venous blood with DPS.

P-glycoprotein (P-gp, ABCB1) is an efflux transporter at the blood–brain barrier (BBB), which mediates clearance of beta-amyloid (Aβ) from brain into blood. We used ( R)-[11C]verapamil PET in combination with partial P-gp inhibition with tariquidar to measure cerebral P-gp function in a beta-amyloidosis mouse model (APPtg) and in control mice at three different ages (50, 200 and 380 days). Following tariquidar pre-treatment (4 mg/kg), whole brain-to-plasma radioactivity concentration ratios ( Kp,brain) were significantly higher in APPtg than in wild-type mice aged 50 days, pointing to decreased cerebral P-gp function. Moreover, we found an age-dependent decrease in cerebral P-gp function in both wild-type and APPtg mice of up to −50%. Alterations in P-gp function were more pronounced in Aβ-rich brain regions (hippocampus, cortex) than in a control region with negligible Aβ load (cerebellum). PET results were confirmed by immunohistochemical staining of P-gp in brain microvessels. Our results confirm previous findings of reduced P-gp function in Alzheimer’s disease mouse models and show that our PET protocol possesses adequate sensitivity to measure these functional changes in vivo. Our PET protocol may find use in clinical studies to test the efficacy of drugs to induce P-gp function at the human BBB to enhance Aβ clearance.

SummaryThe worldwide prevalence of dementia is estimated at 35.6 million and will rise to 115 million by 2050. There is therefore an urgent need for well-founded dementia diagnostics and well-researched therapeutic options. Previous studies have highlighted that spermidine has the ability to trigger the important process of dissolving amyloid-beta plaques by autophagy. They also confirmed that nutritional intervention with the natural polyamine spermidine can prevent memory loss in aging model organisms. This multicentric double-blind preliminary study focused on the effect of oral spermidine supplementation on older adults’ cognitive performance. Memory tests were carried out on 85 subjects aged between 60 and 96 years in 6 nursing homes in Styria. Blood samples were taken for the determination of spermidine concentration and measurement of metabolic parameters. The results demonstrated a clear correlation between the intake of spermidine and the improvement in cognitive performance in subjects with mild and moderate dementia in the group treated with the higher spermidine dosage. The most substantial improvement in test performance was found in the group of subjects with mild dementia with an increase of 2.23 points (p = 0.026) in the mini mental state examination (MMSE) and 1.99 (p = 0.47) in phonematic fluidity. By comparison, the group which had a lower spermidine intake showed consistent or declining cognitive performance.

Objectives From previous data in animal models of cerebral ischemia, lipocalin-2 (LCN2), a protein related to neutrophil function and cellular iron homeostasis, is supposed to have a value as a biomarker in ischemic stroke patients. Therefore, we examined LCN2 expression in the ischemic brain in an animal model and measured plasma levels of LCN2 in ischemic stroke patients. Methods In the mouse model of transient middle cerebral artery occlusion (tMCAO), LCN2 expression in the brain was analyzed by immunohistochemistry and correlated to cellular nonheme iron deposition up to 42 days after tMCAO. In human stroke patients, plasma levels of LCN2 were determined one week after ischemic stroke. In addition to established predictive parameters such as age, National Institutes of Health Stroke Scale and thrombolytic therapy, LCN2 was included into linear logistic regression modeling to predict clinical outcome at 90 days after stroke. Results Immunohistochemistry revealed expression of LCN2 in the mouse brain already at one day following tMCAO, and the amount of LCN2 subsequently increased with a maximum at 2 weeks after tMCAO. Accumulation of cellular nonheme iron was detectable one week post tMCAO and continued to increase. In ischemic stroke patients, higher plasma levels of LCN2 were associated with a worse clinical outcome at 90 days and with the occurrence of post-stroke infections. Conclusions LCN2 is expressed in the ischemic brain after temporary experimental ischemia and paralleled by the accumulation of cellular nonheme iron. Plasma levels of LCN2 measured in patients one week after ischemic stroke contribute to the prediction of clinical outcome at 90 days and reflect the systemic response to post-stroke infections.

Background Netrin-1, a secreted laminin-related protein, is known to regulate not only axonal guidance and neuronal cell migration, but also blood–brain barrier integrity and inflammation. Two preliminary studies reported altered serum netrin-1 levels in multiple sclerosis; however, associations with longitudinal clinical and magnetic resonance imaging activity have not been investigated. Objectives We aimed to assess serum netrin-1 in multiple sclerosis and controls with respect to disease activity and its temporal dynamics. Methods Serum netrin-1 was assessed by enzyme-linked immunosorbent assay in 79 patients with clinically isolated syndrome or multiple sclerosis, and 30 non-inflammatory neurological disease controls. In patients, serum samples were collected immediately prior to gadolinium-enhanced 3 T magnetic resonance imaging at two time points (initial contrast-enhancing gadolinium+ n = 47, non-enhancing gadolinium– n = 32; reference gadolinium– n = 70; median time-lag 1.4, interquartile range 1.0–2.3 years). Results Serum netrin-1 levels were similar in clinically isolated syndrome, multiple sclerosis and controls, and gadolinium+ and gadolinium– patients. Among gadolinium+ patients, serum netrin-1 was decreased in clinically active ( n = 8) vs non-active patients ( n = 39; p = 0.041). Serum netrin-1 showed no temporal dynamics in multiple sclerosis and was unrelated to clinical data. Conclusions Serum netrin-1 levels show no multiple sclerosis specific changes and are not sensitive for detection of subclinical disease activity. Netrin-1 changes during relapses may deserve further examination.