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Dementia in Alzheimer´s disease is a global challenge. There is growing evidence that investigating blood biomarkers to diagnose Alzheimer´s disease is a promising fast, minimally invasive, and less costly method. The aim of this study was to review available studies on promising biomarkers for Alzheimer´s disease.The latest studies were collated for this review.Immunoassays followed by mass spectrometry and immunomagnetic reduction were reported to be highly relevant methods for detecting amyloid-ß 42 (Aß42) and amyloid-ß 40 (Aß40) to calculate the Aß42/Aß40 ratio, thereby improving the early diagnosis of Alzheimer´s disease. Amyloid-ß (Aß) peptides in blood plasma were considered as potential markers, as they correlated with the brain's Aß pathology. Phosphorylated tau protein 181 (p-tau181), phosphorylated tau protein 217 (p-tau217) and phosphorylated tau protein 231 (p-tau231) in blood samples assessed via Simoa technology served as parameters for the early and differential diagnosis of AD, and were markers of tau pathology in the brain. Neurofilament light chain (Nfl) and glial fibrillary acid protein (GFAP) were additional markers possibly facilitating the assessment of axonal and astroglial brain damage in Alzheimer´s disease. GFAP in blood was useful as an additional marker to detect early and to predict the time course of Alzheimer´s disease.Determining blood biomarkers represents less invasive and less costly diagnostics for Alzheimer´s disease. The investigation of blood biomarkers such as the Aß42/Aß40 ratio, p-tau217, p-tau231, Nfl and GFAP have been promising in establishing the AT(N) classification for Alzheimer´s disease. High-throughput methods should be evaluated in large patient cohort studies and via meta-analyses of studies. Consensus criteria with standard protocols for measuring these biomarkers while considering ethical issues and Alzheimer´s phenotype should unify normative values from different laboratories. The AT(N) classification of Alzheimer´s disease in blood would be a key element towards the implementation of minimally-invasive precision medicine.Die Demenz bei Alzheimer-Krankheit ist eine globale Herausforderung. Studien weisen auf Blutbiomarker zur Diagnose der Alzheimer-Krankheit als eine minimal invasive, schnellere, kostengünstigere und daher zukunftsträchtige Methode hin. Ziel dieser Übersicht ist es, Studien zu vielversprechenden Biomarkern der Alzheimer-Krankheit darzustellen.Für diese Übersichtsarbeit wurden aktuelle Studien zusammengestellt.Immunassays mit anschließender Massenspektrometrie und solche mit immunmagnetischer Reduktion sind aussichtsreiche Methoden für die Bestimmung von Amyloid-ß 42 (Aß42) und Amyloid-ß 40 (Aß40) für die Bildung der Ratio von Aß42/Aß40 zur blutbasierten Früh- und Differentialdiagnostik der Alzheimer-Krankheit. Die Amyloid-ß (Aß) Peptide im Blutplasma sind ein potentieller Marker der Aß-Pathologie, da sie mit der Aß-Pathologie im Gehirn korrelieren. Das mittels der Simoa Technologie bestimmte phosphorylierte Tau-Protein 181 (p-tau181), das phosphorylierte Tau Protein 231 (p-tau231) und das phosphorylierte Tau Protein 217 (p-tau217) im Blut sind vielversprechend hinsichtlich einer möglichen Optimierung der Früh- und Differentialdiagnostik der Alzheimer-Krankheit und sind Marker einer Tau-Pathologie im Gehirn. Die Neurofilamente Leichtketten (Nfl) und das saure Gliafaserprotein (GFAP) sind als Zusatzmarker hilfreich, um eine axonale und astrogliale Hirnschädigung bei Alzheimer-Krankheit zu beurteilen. GFAP im Blut könnte vor allem als Zusatzmarker zur Frühdiagnostik und Prädiktion des Verlaufs der Alzheimer-Krankheit sinnvoll sein.Blutbasierte Biomarker sind ein wichtiger Schritt in Richtung einer weniger invasiven und kostengünstigeren Diagnostik der Alzheimer-Krankheit. Die Ratio Aß42/Aß40, das p-tau181, das p-tau217, das p-tau231, die Nfl und das GFAP sind vielversprechende Blutbiomarker unter Beachtung der AT(N) Klassifikation der Alzheimer-Krankheit. Hochdurchsatzfähige Methoden sollten in großen Kohorten und Metanalysen evaluiert werden. Zudem sollten Konsensus Kriterien mit einheitlichen Protokollen mit Normwerten zur Messung dieser Biomarker erstellt werden. Die Etablierung der AT(N) Klassifikation der Alzheimer-Krankheit im Blut ist unter Berücksichtigung ethischer Gesichtspunkte sowie des Alzheimer Phänotyps ein wichtiger Baustein für die Implementierung einer minimal-invasiven Präzisionsmedizin.

Zusammenfassung Ziele der Studie Die Demenz bei Alzheimer-Krankheit ist eine globale Herausforderung. Studien weisen auf Blutbiomarker zur Diagnose der Alzheimer-Krankheit als eine minimal invasive, schnellere, kostengünstigere und daher zukunftsträchtige Methode hin. Ziel dieser Übersicht ist es, Studien zu vielversprechenden Biomarkern der Alzheimer-Krankheit darzustellen. Methodik Für diese Übersichtsarbeit wurden aktuelle Studien zusammengestellt. Ergebnisse Immunassays mit anschließender Massenspektrometrie und solche mit immunmagnetischer Reduktion sind aussichtsreiche Methoden für die Bestimmung von Amyloid-ß 42 (Aß42) und Amyloid-ß 40 (Aß40) für die Bildung der Ratio von Aß42/Aß40 zur blutbasierten Früh- und Differentialdiagnostik der Alzheimer-Krankheit. Die Amyloid-ß (Aß) Peptide im Blutplasma sind ein potentieller Marker der Aß-Pathologie, da sie mit der Aß-Pathologie im Gehirn korrelieren. Das mittels der Simoa Technologie bestimmte phosphorylierte Tau-Protein 181 (p-tau181), das phosphorylierte Tau Protein 231 (p-tau231) und das phosphorylierte Tau Protein 217 (p-tau217) im Blut sind vielversprechend hinsichtlich einer möglichen Optimierung der Früh- und Differentialdiagnostik der Alzheimer-Krankheit und sind Marker einer Tau-Pathologie im Gehirn. Die Neurofilamente Leichtketten (Nfl) und das saure Gliafaserprotein (GFAP) sind als Zusatzmarker hilfreich, um eine axonale und astrogliale Hirnschädigung bei Alzheimer-Krankheit zu beurteilen. GFAP im Blut könnte vor allem als Zusatzmarker zur Frühdiagnostik und Prädiktion des Verlaufs der Alzheimer-Krankheit sinnvoll sein. Schlussfolgerungen Blutbasierte Biomarker sind ein wichtiger Schritt in Richtung einer weniger invasiven und kostengünstigeren Diagnostik der Alzheimer-Krankheit. Die Ratio Aß42/Aß40, das p-tau181, das p-tau217, das p-tau231, die Nfl und das GFAP sind vielversprechende Blutbiomarker unter Beachtung der AT(N) Klassifikation der Alzheimer-Krankheit. Hochdurchsatzfähige Methoden sollten in großen Kohorten und Metanalysen evaluiert werden. Zudem sollten Konsensus Kriterien mit einheitlichen Protokollen mit Normwerten zur Messung dieser Biomarker erstellt werden. Die Etablierung der AT(N) Klassifikation der Alzheimer-Krankheit im Blut ist unter Berücksichtigung ethischer Gesichtspunkte sowie des Alzheimer Phänotyps ein wichtiger Baustein für die Implementierung einer minimal-invasiven Präzisionsmedizin.

Many approaches were made in recent years to establish urine PCR as a diagnostic tool for Lyme borreliosis, but results are contradictory. In the present study, a standardized protocol spiking urine from healthy donors with a defined amount of whole Borrelia or Borrelia DNA was established. The development of a nested real-time PCR targeting ospA enabled a highly sensitive and quantitative analysis of these samples. We show the following. (i) Storage of spiked urine samples for up to 6 months at −20°C had no negative effect on spike recovery. (ii) Centrifugation of 10 ml of urine at 40,000 × g for 30 min resulted in a concentration of both spikes, i.e., whole Borrelia and DNA. (iii) The inhibition of DNA spike recovery in 48% (11 of 23 samples) of urine samples tested could be attributed to nuclease activity. This was abrogated by alkalizing the urine or by working with the samples on ice. Despite optimized conditions, analysis of urine samples of 12 patients with erythema migrans, the clinical stage considered to be associated with the highest bacterial load, revealed a positive result in only one sample. All 12 samples were negative by an alternative PCR targeting flagellin. The results of our study support doubts that urine is a suitable material for diagnosis of Lyme borreliosis.

The phage surface display technique was used to identify Borrelia burgdorferi antigens. By affinity selection with immunoglobulin G from pooled sera of six Lyme borreliosis (LB) patients, the ribosomal protein L25 was identified. The diagnostic value of L25 was investigated by an enzyme-linked immunosorbent assay, using sera from 80 LB patients and 75 controls, and the use of the protein resulted in a specificity of 99% and a 23% sensitivity, which qualify L25 as a useful antigen when combined with others.

In Europe, Borrelia burgdorferi genospecies causing Lyme borreliosis are mainly transmitted by the tick Ixodes ricinus . Since its discovery, B. burgdorferi has been the subject of many epidemiological studies to determine its prevalence and the distribution of the different genospecies in ticks. In the current study we systematically reviewed the literature on epidemiological studies of I. ricinus ticks infected with B. burgdorferi sensu lato. A total of 1,186 abstracts in English published from 1984 to 2003 were identified by a PubMed keyword search and from the compiled article references. A multistep filter process was used to select relevant articles; 110 articles from 24 countries contained data on the rates of infection of I. ricinus with Borrelia in Europe (112,579 ticks), and 44 articles from 21 countries included species-specific analyses (3,273 positive ticks). These data were used to evaluate the overall rate of infection of I. ricinus with Borrelia genospecies, regional distributions within Europe, and changes over time, as well as the influence of different detection methods on the infection rate. While the infection rate was significantly higher in adults (18.6%) than in nymphs (10.1%), no effect of detection method, tick gender, or collection period (1986 to 1993 versus 1994 to 2002) was found. The highest rates of infection of I. ricinus were found in countries in central Europe. B. afzelii and B. garinii are the most common Borrelia species, but the distribution of genospecies seems to vary in different regions in Europe. The most frequent coinfection by Borrelia species was found for B. garinii and B. valaisiana .

If left untreated, infection withBorrelia burgdorferisensu lato may lead to chronic Lyme borreliosis. It is still unknown how this pathogen manages to persist in the host in the presence of competent immune cells. It was recently reported thatBorreliasuppresses the host's immune response, thus perhaps preventing the elimination of the pathogen (I. Diterich, L. Härter, D. Hassler, A. Wendel, and T. Hartung, Infect. Immun. 69:687-694, 2001). Here, we further characterizeBorrelia-induced immunomodulation in order to develop a model of this anergy. We observed that the differentBorreliapreparations that we tested, i.e., live, heat-inactivated, and sonicatedBorrelia, could desensitize human blood monocytes, as shown by attenuated cytokine release upon restimulation with any of the different preparations. Next, we investigated whether theseBorrelia-specific stimuli render monocytes tolerant, i.e. hyporesponsive, towards another Toll-like receptor 2 (TLR2) agonist, such as lipoteichoic acid from gram-positive bacteria, or towards the TLR4 agonist lipopolysaccharide. Cross-tolerance towards all tested stimuli was induced. Furthermore, using primary bone marrow cells from TLR2-deficient mice and from mice with a nonfunctional TLR4 (strain C3H/HeJ), we demonstrated that the TLR2 was required for tolerance induction byBorrelia, and using neutralizing antibodies, we identified interleukin-10 as the key mediator involved. Although peripheral blood mononuclear cells tolerized byBorreliaexhibited reduced TLR2 and TLR4 mRNA levels, the expression of the respective proteins on monocytes was not decreased, ruling out the possibility that tolerance toBorreliais attributed to a reduced TLR2 expression. In summary, we characterized tolerance induced byB. burgdorferi, describing a model of desensitization which might mirror the immunosuppression recently attributed to the persistence ofBorreliain immunocompetent hosts.

A LightCycler-based PCR protocol was developed which targets the ospA gene for the identification and quantification of the different Borrelia burgdorferi sensu lato species in culture and in ticks, based on the use of a fluorescently labeled probe (HybProbe) and an internally labeled primer. The detection limit of the PCR was 1 to 10 spirochetes. A melting temperature determined from the melting curve of the amplified product immediately after thermal cycling allowed the differentiation of the three different B. burgdorferi sensu lato genospecies ( B. burgdorferi sensu stricto, Borrelia garinii , and Borrelia afzelii ) that are clinically relevant in Europe in a single PCR run. This method represents a simplified approach to study the association of different Borrelia species in ticks, the risk of Lyme borreliosis, and the putatively species-specific clinical sequelae. To determine the reliability of the real-time PCR protocol, we studied the prevalence of B. burgdorferi sensu lato infection in Ixodes ricinus ticks. A total of 1,055 ticks were collected by flagging vegetation in five different sites in the region of Konstanz (south Germany) and were examined for the distribution of B. burgdorferi species by real-time PCR. The mean infection rate was 35%. Of 548 adult ticks, 40% were positive, and of 507 nymphs, 30% were positive. The predominant genospecies (with 18% mixed infections) in the examined areas was B. afzelii (53%), followed by B. garinii (18%) and B. burgdorferi sensu stricto (11%); 0.8% of the infecting Borrelia could not be identified.