Investigation of the impact of biogeographic ancestry on DNA methylation based age predictions comparing a Middle East and a Central European population

DNA methylation based age prediction is a new method in the toolbox of forensic genetics. Typically, the method is applied in the course of police investigation e.g. to predict the age of an unknown person that has left a biological trace at a crime scene. The method can also be used to answer other forensic questions, for example to estimate the age of unknown human bodies in the course of the identification process. In the present study, we tested for a potential impact of biogeographic ancestry (BGA) on age predictions using five age dependent methylated CpG sites within the genetic regions of ELOVL2, MIR29B2CHG, FHL2, KLF14 and TRIM59. We collected 102 blood samples each from donors living in Iraq, Middle East (ME) and Germany, Central Europe (EU). Both sample sets were matched in sex and age ranging from 18 to 68 years with exactly one male and female sample per year of age. All samples were analyzed by bisulfite pyrosequencing applying a multiplex pre-amplification strategy based on a single input of 35 ng converted DNA in the PCR. For the CpGs in MIR29B2CHG, FHL2 and KLF14, we observed significantly different methylation levels between the two populations. While we were able to train two highly accurate prediction models for the respective population with mean absolute deviations between predicted and actual ages (MAD) of 3.34 years for the ME model, and 2.72 years for the EU model, we found an absolute prediction difference between the two population specific models of more than 4 years. A combined model for both populations compensated the methylation difference between the two populations, providing MADs of prediction of only 3.81 years for ME and 3.31 years for EU samples. In total, the results of the present study strongly support the benefit of BGA information for more reliable methylation based age predictions.

Evaluation of Single Nucleotide Variants in Intron 1 of the ABO Gene as Diagnostic Markers for the A1 Blood Group

Introduction

The molecular diagnosis of the A1 blood group is based on the exclusion of ABO gene variants causing blood groups A2, B, or O. A specific genetic marker for the A1 blood group is still missing. Recently, long-read ABO sequencing revealed four sequence variations in intron 1 as promising markers for the ABO*A1 allele. Here, we evaluated the diagnostic values of the 4 variants in blood donors with regular and weak A phenotypes and genotypes.

Methods

ABO phenotype data (A, B, AB, or O) were taken from the blood donor files. The ABO genotypes (low resolution) were known from a previous study and included the variants c.261delG, c.802G>A, c.803G>C, and c.1061delC. ABO variant alleles (ABO*AW.06,*AW.08,*AW.09,*AW.13, *AW.30, and *A3.02) were identified in weak A donors by sequencing the ABO exons before. For genotyping of the ABO intron 1 variants rs532436, rs1554760445, rs507666, and rs2519093, we applied TaqMan assays with endpoint fluorescence detection according to a standard protocol. Genotypes of the variants were compared with the ABO phenotype and genotype. Evaluation of diagnostic performance included sensitivity, specificity, positive (PPV), and negative predictive value (NPV).

Results

In 1,330 blood donors with regular ABO phenotypes and genotypes, the intron 1 variants were significantly associated with the proposed A1 blood group. In 15 donors, we found discrepancies to the genotype of at least one of the 4 variants. For the diagnosis of the ABO*A1 allele, the variants showed 98.79-99.48% sensitivity, 99.66-99.81% specificity, 98.80-99.31% PPV, and 99.66-99.86% NPV. Regarding the A phenotype, the diagnostic values were 99.02-99.41% sensitivity, 99.63-99.76% specificity, 99.41-99.61% PPV, and 99.39-99.63% NPV. The *A1 marker allele of all intron 1 variants was also associated with the *AW.06, *AW.13, and *AW.30 variants. Samples with *AW.08, *AW.09, and *A3.02 variants lacked this association.

Conclusion

The ABO intron 1 variants revealed significant association with the ABO*A1 allele and the A phenotype. However, the intron 1 genotype does not exclude variant alleles causing weak A phenotypes. With the introduction of reliable tag, single nucleotide variants for the A1, A2, B, and O blood groups and the genotyping instead of phenotyping of the ABO blood group are getting more feasible on a routine basis.

Correlation between Clinical Characteristics and Antibody Levels in COVID-19 Convalescent Plasma Donor Candidates

COVID-19 convalescent plasma (CCP) with high neutralizing antibodies has been suggested in preventing disease progression in COVID-19. In this study, we investigated the relationship between clinical donor characteristics and neutralizing anti-SARS-CoV-2 antibodies in CCP donors. COVID-19 convalescent plasma donors were included into the study. Clinical parameters were recorded and anti-SARS-CoV-2 antibody levels (Spike Trimer, Receptor Binding Domain (RBD), S1, S2 and nucleocapsid protein) as well as ACE2 binding inhibition were measured. An ACE2 binding inhibition < 20% was defined as an inadequate neutralization capacity. Univariate and multivariable logistic regression analysis was used to detect the predictors of inadequate neutralization capacity. Ninety-one CCP donors (56 female; 61%) were analyzed. A robust correlation between all SARS-CoV-2 IgG antibodies and ACE2 binding inhibition, as well as a positive correlation between donor age, body mass index, and a negative correlation between time since symptom onset and antibody levels were found. We identified time since symptom onset, normal body mass index (BMI), and the absence of high fever as independent predictors of inadequate neutralization capacity. Gender, duration of symptoms, and number of symptoms were not associated with SARS-CoV-2 IgG antibody levels or neutralization. Neutralizing capacity was correlated with SARS-CoV-2 IgG antibodies and associated with time since symptom onset, BMI, and fever. These clinical parameters can be easily incorporated into the preselection of CCP donors.

Humoral SARS-CoV-2 Immune Response in COVID-19 Recovered Vaccinated and Unvaccinated Individuals Related to Post-COVID-Syndrome

BACKGROUND

The duration of anti-SARS-CoV-2-antibody detectability up to 12 months was examined in individuals after either single convalescence or convalescence and vaccination. Moreover, variables that might influence an anti-RBD/S1 antibody decline and the existence of a post-COVID-syndrome (PCS) were addressed.

METHODS

Forty-nine SARS-CoV-2-qRT-PCR-confirmed participants completed a 12-month examination of anti-SARS-CoV-2-antibody levels and PCS-associated long-term sequelae. Overall, 324 samples were collected. Cell-free DNA (cfDNA) was isolated and quantified from EDTA-plasma. As cfDNA is released into the bloodstream from dying cells, it might provide information on organ damage in the late recovery of COIVD-19. Therefore, we evaluated cfDNA concentrations as a biomarker for a PCS. In the context of antibody dynamics, a random forest-based logistic regression with antibody decline as the target was performed and internally validated.

RESULTS

The mean percentage dynamic related to the maximum measured value was 96 (±38)% for anti-RBD/S1 antibodies and 30 (±26)% for anti-N antibodies. Anti-RBD/S1 antibodies decreased in 37%, whereas anti-SARS-CoV-2-anti-N antibodies decreased in 86% of the subjects. Clinical anti-RBD/S1 antibody decline prediction models, including vascular and other diseases, were cross-validated (highest AUC 0.74). Long-term follow-up revealed no significant reduction in PCS prevalence but an increase in cognitive impairment, with no indication for cfDNA as a marker for a PCS.

CONCLUSION

Long-term anti-RBD/S1-antibody positivity was confirmed, and clinical parameters associated with declining titers were presented. A fulminant decrease in anti-SARS-CoV-2-anti-N antibodies was observed (mean change to maximum value 30 (±26)%). Anti-RBD/S1 antibody titers of SARS-CoV-2 recovered subjects boosted with a vaccine exceeded the maximum values measured after single infection by 235 ± 382-fold, with no influence on preexisting PCS. PCS long-term prevalence was 38.6%, with an increase in cognitive impairment compromising the quality of life. Quantified cfDNA measured in the early post-COVID-19 phase might not be an effective marker for PCS identification.

Genetic analysis of the aquaporin water channels AQP12A and AQP12B in patients with chronic pancreatitis

BACKGROUND

Alterations in genes specifically expressed in the pancreas have been associated with chronic pancreatitis (CP). A significant percentage of patients with non-alcoholic CP, however, do not have mutations in known risk genes, suggesting the existence of further susceptibility genes. Four aquaporins are expressed in the exocrine pancreas: AQP1, AQP5, AQP8 and AQP12, the latter being found exclusively in this organ. Therefore, we investigated the two AQP12 genes, AQP12A and AQP12B, in CP patients.

METHODS

We analyzed all exons and adjacent intronic regions of AQP12A and AQP12B in 292 German patients with non-alcoholic CP and 143 control subjects by direct DNA sequencing.

RESULTS

In total, we discovered 41 non-synonymous changes, three of which were nonsense variants. Genotype and allele frequencies of these variants did not differ significantly between patients and controls (all p-values >0.05). Remarkably, we found a common nonsense variant in AQP12B, p.S152Tfs∗24, with an allele frequency of 15.7% in controls, including 2.8% homozygous subjects. This finding suggests that AQP12B is physiologically dispensable for normal pancreatic function.

CONCLUSIONS

Our results suggest that genetic alterations in AQP12A and AQP12B do not predispose to the development of non-alcoholic CP.

Booster dose of mRNA vaccine augments waning T cell and antibody responses against SARS-CoV-2

A gradual decay in humoral and cellular immune responses over time upon SAR1S-CoV-2 vaccination may cause a lack of protective immunity. We conducted a longitudinal analysis of antibodies, T cells, and monocytes in 25 participants vaccinated with mRNA or ChAdOx1-S up to 12 weeks after the 3^rd (booster) dose with mRNA vaccine. We observed a substantial increase in antibodies and CD8 T cells specific for the spike protein of SARS-CoV-2 after vaccination. Moreover, vaccination induced activated T cells expressing CD69, CD137 and producing IFN-γ and TNF-α. Virus-specific CD8 T cells showed predominantly memory phenotype. Although the level of antibodies and frequency of virus-specific T cells reduced 4-6 months after the 2^nd dose, they were augmented after the 3^rd dose followed by a decrease later. Importantly, T cells generated after the 3^rd vaccination were also reactive against Omicron variant, indicated by a similar level of IFN-γ production after stimulation with Omicron peptides. Breakthrough infection in participants vaccinated with two doses induced more SARS-CoV-2-specific T cells than the booster vaccination. We found an upregulation of PD-L1 expression on monocytes but no accumulation of myeloid cells with MDSC-like immunosuppressive phenotype after the vaccination. Our results indicate that the 3^rd vaccination fosters antibody and T cell immune response independently from vaccine type used for the first two injections. However, such immune response is attenuated over time, suggesting thereby the need for further vaccinations.

Genetic Analysis of the ATG16L1 c.898A>G (p.T300A) Variant in Acute and Chronic Pancreatitis

OBJECTIVES

Human and animal studies suggest an important role of autophagy in the pathogenesis of pancreatitis. ATG16L1 (autophagy-related 16 like 1) is part of a protein complex that is involved in the formation of autophagosomes. The c.898A > G (p.T300A) variant of ATG16L1 is associated with Crohn disease. In this study, we analyzed ATG16L1 c.898A > G (p.T300A) for an association with pancreatitis.

METHODS

We genotyped 777 patients and 551 control subjects of German origin by melting curve analysis using fluorescence resonance energy transfer probes. The patient group included 429 patients with nonalcoholic chronic pancreatitis (CP), 141 patients with alcoholic CP, and 207 patients with acute pancreatitis (AP). We classified AP by severity according to the Atlanta symposium 1992.

RESULTS

Allele and genotype frequencies of ATG16L1 c.898A > G (p.T300A) did not differ significantly between patients and controls (G allele frequencies: nonalcoholic CP, 49.9%; alcoholic CP, 48.2%; AP, 49.5%; controls, 52.7%). We found no significant association with the severity of AP either.

CONCLUSIONS

Our data do not support a role of ATG16L1 c.898A > G (p.T300A) in the pathogenesis of AP or CP or an influence on the severity of AP.

Platelets and Sera from Donors of Convalescent Plasma after Mild COVID-19 Show No Procoagulant Phenotype

Coronavirus disease-2019 (COVID-19) is associated with increased thromboembolic complications. Long-term alteration in the coagulation system after acute COVID-19 infection is still a subject of research. Furthermore, the effect of sera from convalescent subjects on platelets is not known. In this study, we investigated platelet phenotype, coagulation, and fibrinolysis in COVID-19 convalescent plasma (CCP) donors and analyzed convalescent sera-induced effects on platelets. We investigated CCP donors who had a history of mild COVID-19 infection and donors who did not have COVID-19 were used as controls. We analyzed phosphatidylserine (PS) externalization, CD62p expression, and glycoprotein VI (GPVI) shedding both in platelet-rich plasma (PRP) and after incubation of washed healthy platelets with donors' sera using flow cytometry. Coagulation and fibrinolysis systems were assessed with thromboelastometry. Forty-seven CCP donors (22 males, 25 females; mean age (±SD): 41.4 ± 13.7 years) with a history of mild COVID-19 infection were included. Median duration after acute COVID-19 infection was 97 days (range, 34–401). We did not find an increased PS externalization, CD62p expression, or GPVI shedding in platelets from CCP donors. Sera from CCP donors did not induce PS externalization or GPVI shedding in healthy platelets. Sera-induced CD62p expression was slightly, albeit statistically significantly, lower in CCP donors than in plasma donors without a history of COVID-19. One patient showed increased maximum clot firmness and prolonged lysis time in thromboelastometry. Our findings suggest that procoagulant platelet phenotype is not present after mild COVID-19. Furthermore, CCP sera do not affect the activation status of platelets.

Loss-of-function variant in chymotrypsin like elastase 3B (CELA3B) is associated with non-alcoholic chronic pancreatitis

BACKGROUND

Genetic alterations in digestive enzymes have been associated with chronic pancreatitis (CP). Recently, chymotrypsin like elastase 3B (CELA3B) emerged as a novel risk gene. Thus, we evaluated CELA3B in two European cohorts with CP.

METHODS

We analyzed all 8 CELA3B exons in 550 German non-alcoholic CP (NACP) patients and in 241 German controls by targeted DNA sequencing. In addition, we analyzed exons 6 and 7 by Sanger sequencing and the c.129+1G>A variant by melting curve analysis in 1078 further German controls. As replication cohort, we investigated up to 243 non-German European NACP patients and up to 1665 controls originating from Poland, Hungary, and Sweden. We assessed the cellular secretion and the elastase activity of recombinant CELA3B variants.

RESULTS

In the German discovery cohort, we detected a splice-site variant in intron 2, c.129+1G>A, in 9/550 (1.64%) CP patients and in 5/1319 (0.38%) controls (P=0.007, OR=4.4, 95% CI=1.5-13.0). In the European replication cohort, this variant was also enriched in patients (9/178 [5.06%]) versus controls (13/1247 [1.04%]) (P=0.001, OR=5.1, 95% CI=2.1-12.0). We did not find the two previously reported codon 90 variants, p.R90C and p.R90L.

CONCLUSIONS

Our data indicate that CELA3B is a susceptibility gene for CP. In contrast to previous reports suggesting that increased CELA3B activity is associated with CP risk, the splice-site variant identified here is predicted to cause diminished CELA3B expression. How reduced CELA3B function predisposes to pancreatitis remains to be elucidated.

Pooled human bone marrow-derived mesenchymal stromal cells with defined trophic factors cargo promote dermal wound healing in diabetic rats by improved vascularization and dynamic recruitment of M2-like macrophages

Human Mesenchymal Stromal Cells (hMSCs) are a promising source for cell-based therapies. Yet, transition to phase III and IV clinical trials is remarkably slow. To mitigate donor variabilities and to obtain robust and valid clinical data, we aimed first to develop a manufacturing concept balancing large-scale production of pooled hMSCs in a minimal expansion period, and second to test them for key manufacture and efficacy indicators in the clinically highly relevant indication wound healing. Our novel clinical-scale manufacturing concept is comprised of six single donor hMSCs master cell banks that are pooled to a working cell bank from which an extrapolated number of 70,000 clinical doses of 1x10⁶ hMSCs/cm² wound size can be manufactured within only three passages. The pooled hMSC batches showed high stability of key manufacture indicators such as morphology, immune phenotype, proliferation, scratch wound healing, chemotactic migration and angiogenic support. Repeated topical hMSCs administration significantly accelerated the wound healing in a diabetic rat model by delivering a defined growth factor cargo (specifically BDNF, EGF, G-CSF, HGF, IL-1α, IL-6, LIF, osteopontin, VEGF-A, FGF-2, TGF-β, PGE-2 and IDO after priming) at the specific stages of wound repair, namely inflammation, proliferation and remodeling. Specifically, the hMSCs mediated epidermal and dermal maturation and collagen formation, improved vascularization, and promoted cell infiltration. Kinetic analyses revealed transient presence of hMSCs until day (d)4, and the dynamic recruitment of macrophages infiltrating from the wound edges (d3) and basis (d9), eventually progressing to the apical wound on d11. In the wounds, the hMSCs mediated M2-like macrophage polarization starting at d4, peaking at d9 and then decreasing to d11. Our study establishes a standardized, scalable and pooled hMSC therapeutic, delivering a defined cargo of trophic factors, which is efficacious in diabetic wound healing by improving vascularization and dynamic recruitment of M2-like macrophages. This decision-making study now enables the validation of pooled hMSCs as treatment for impaired wound healing in large randomized clinical trials.

Increased plasma level of soluble P-selectin in non-hospitalized COVID-19 convalescent donors

Background

The coronavirus disease-2019 (COVID-19) is a systemic disease with severe implications on the vascular and coagulation system. A procoagulant platelet phenotype has been reported at least in the acute disease phase. Soluble P-selectin (sP-sel) in the plasma is a surrogate biomarker of platelet activation. Increased plasma levels of sP-sel have been reported in hospitalized COVID-19 patients associated with disease severity. Here, we evaluated in a longitudinal study the sP-sel plasma concentration in blood donors who previously suffered from moderate COVID-19.

Methods

154 COVID-19 convalescent and 111 non-infected control donors were recruited for plasma donation and for participation in the CORE research trial. First donation (T1) was performed 43–378 days after COVID-19 diagnosis. From most of the donors the second (T2) plasma donation including blood sampling was obtained after a time period of 21–74 days and the third (T3) donation after additional 22–78 days. Baseline characteristics including COVID-19 symptoms of the donors were recorded based on a questionnaire. Platelet function was measured at T1 by flow cytometry and light transmission aggregometry in a representative subgroup of 25 COVID-19 convalescent and 28 control donors. The sP-sel plasma concentration was determined in a total of 704 samples by using a commercial ELISA.

Results

In vitro platelet function was comparable in COVID-19 convalescent and control donors at T1. Plasma samples from COVID-19 convalescent donors revealed a significantly higher sP-sel level compared to controls at T1 (1.05 ± 0.42 ng/mL vs. 0.81 ± 0.30 ng/mL; p < 0.0001) and T2 (0.96 ± 0.39 ng/mL vs. 0.83 ± 0.38 ng/mL; p = 0.0098). At T3 the sP-sel plasma level was comparable in both study groups. Most of the COVID-19 convalescent donors showed a continuous decrease of sP-sel from T1 to T3.

Conclusion

Increased sP-sel plasma concentration as a marker for platelet or endothelial activation could be demonstrated even weeks after moderate COVID-19, whereas, in vitro platelet function was comparable with non-infected controls. We conclude that COVID-19 and additional individual factors could lead to an increase of the sP-sel plasma level.

Variants in the pancreatic CUB and zona pellucida-like domains 1 (CUZD1) gene in early-onset chronic pancreatitis - A possible new susceptibility gene

OBJECTIVE

Non-alcoholic chronic pancreatitis (NACP) frequently develops in the setting of genetic susceptibility associated with alterations in genes that are highly expressed in the pancreas. However, the genetic basis of NACP remains unresolved in a significant number of patients warranting a search for further risk genes.

DESIGN

We analyzed CUZD1, which encodes the CUB and zona pellucida-like domains 1 protein that is found in high levels in pancreatic acinar cells. We sequenced the coding region in 1163 European patients and 2018 European controls. In addition, we analyzed 297 patients and 1070 controls from Japan. We analyzed secretion of wild-type and mutant CUZD1 from transfected cells using Western blotting.

RESULTS

In the European cohort, we detected 30 non-synonymous variants. Using different prediction tools (SIFT, CADD, PROVEAN, PredictSNP) or the combination of these tools, we found accumulation of predicted deleterious variants in patients (p-value range 0.002-0.013; OR range 3.1-5.2). No association was found in the Japanese cohort, in which 13 non-synonymous variants were detected. Functional studies revealed >50% reduced secretion of 7 variants, however, these variants were not significantly enriched in European CP patients.

CONCLUSION

Our data indicate that CUZD1 might be a novel susceptibility gene for NACP. How these variants predispose to pancreatitis remains to be elucidated.

Genetic analysis of pancreatic phospholipase A2 (PLA2G1B) in patients with chronic pancreatitis

BACKGROUND

Genetic mutations in various pancreatic enzymes or their counteracting proteins have been linked to chronic pancreatitis. In particular, variants in the genes encoding pancreatic lipase (PNLIP) and carboxyl ester lipase (CEL) have been associated with pancreatitis. Therefore, we investigated pancreatic phospholipase A2 (PLA2G1B) as a promising candidate gene in patients with chronic pancreatitis.

METHODS

We analyzed all coding exons and adjacent intronic regions of PLA2G1B in 416 German patients with non-alcoholic chronic pancreatitis (NACP) and 186 control subjects by direct DNA sequencing.

RESULTS

We detected 2 frequent synonymous variants in exon 3: c.222T>C (p.Y74 = ) and c.294G>A (p.S98 = ). The genotype and allele frequencies of these variants were similar between patients and controls (c.222 TC: 9.6% in NACP vs. 9.7% in controls; c.222CC: 0.2% in NACP vs. 0% in controls; c.294 GA: 31.3% in NACP vs. 28.0% in controls; c.294AA: 2.4% in NACP vs. 1.1% in controls). All p-values were non-significant. In addition, we found one synonymous variant, c.138C>T (p.N46 = ) and one non-synonymous variant, c.244A>G (p.S82G), in a single case each.

CONCLUSIONS

Our results suggest that genetic alterations in PLA2G1B do not predispose to the development of non-alcoholic chronic pancreatitis.

Recommendation for validation and quality assurance of non-invasive prenatal testing for foetal blood groups and implications for IVD risk classification according to EU regulations

BACKGROUND AND OBJECTIVES

Non-invasive assays for predicting foetal blood group status in pregnancy serve as valuable clinical tools in the management of pregnancies at risk of detrimental consequences due to blood group antigen incompatibility. To secure clinical applicability, assays for non-invasive prenatal testing of foetal blood groups need to follow strict rules for validation and quality assurance. Here, we present a multi-national position paper with specific recommendations for validation and quality assurance for such assays and discuss their risk classification according to EU regulations.

MATERIALS AND METHODS

We reviewed the literature covering validation for in-vitro diagnostic (IVD) assays in general and for non-invasive foetal RHD genotyping in particular. Recommendations were based on the result of discussions between co-authors.

RESULTS

In relation to Annex VIII of the In-Vitro-Diagnostic Medical Device Regulation 2017/746 of the European Parliament and the Council, assays for non-invasive prenatal testing of foetal blood groups are risk class D devices. In our opinion, screening for targeted anti-D prophylaxis for non-immunized RhD negative women should be placed under risk class C. To ensure high quality of non-invasive foetal blood group assays within and beyond the European Union, we present specific recommendations for validation and quality assurance in terms of analytical detection limit, range and linearity, precision, robustness, pre-analytics and use of controls in routine testing. With respect to immunized women, different requirements for validation and IVD risk classification are discussed.

CONCLUSION

These recommendations should be followed to ensure appropriate assay performance and applicability for clinical use of both commercial and in-house assays.

Correlation of CLEC1B haplotypes with plasma levels of soluble CLEC-2 in healthy individuals

Binding of podoplanin to the C-type lectin-like receptor 2 (CLEC-2) promotes platelet activation and soluble CLEC-2 (sCLEC-2) is shed from activated platelets. The role of sCLEC-2 in the plasma is unknown. The expression level and plasma concentration of sCLEC-2 could be affected by variants of the corresponding gene, CLEC1B. Here, we genotyped SNVs in the promoter and coding region of CLEC1B and determined plasma levels of sCLEC-2 in healthy individuals. We genotyped 516 healthy blood donors for 7 SNVs (rs10505743, rs11053538, rs4764178, rs76016091, rs2273986, rs2273987, rs521040) by using PCR methods and calculated haplotypes from the SNV genotypes. For 313 of the donors we measured the sCLEC-2 concentration in EDTA plasma samples by using a commercial ELISA. SNV typing revealed allele frequencies comparable to database information. None of the SNVs showed significant correlation with sCLEC-2 plasma levels. Haplotype analysis indicated 6 haplotypes with frequencies >1% and haplotype h3 was the most frequent (33.8%). Donors homozygous for h3 (n = 37) showed significantly lower sCLEC-2 plasma levels (median 0.95 ng/mL) than donors being h3 negative or heterozygous (n = 276; 1.44 ng/mL; p = .0203). We found that the sCLEC-2 plasma concentration is variable in healthy individuals and the CLEC1B genotype contributes to the expression level.

The three common polymorphisms p.A986S, p.R990G and p.Q1011E in the calcium sensing receptor (CASR) are not associated with chronic pancreatitis

BACKGROUND

The calcium sensing receptor (CASR) is a G protein-coupled receptor that is responsible for assessing extracellular Ca²⁺ levels and thus plays a crucial role in calcium homeostasis. Hypercalcemia is a metabolic risk factor for pancreatitis and rare CASR variants have been described in patients with chronic pancreatitis. At the carboxy-terminal tail of CASR, there is a cluster of three common polymorphisms, p.A986S (rs1801725), p.R990G (rs1042636) and p.Q1011E (rs1801726), which have been associated with chronic pancreatitis in various studies, but with conflicting results.

METHODS

We examined 542 German and 339 French patients with chronic pancreatitis as well as 1025 German controls for the 3 common CASR polymorphism by melting curve analysis. For comparison, we used genotype data from 583 French controls from a previous study. In addition, we functionally analyzed the three variants by NFAT and SRE luciferase reporter systems as well as Western blotting and verified cell surface expression by ELISA.

RESULTS

In both cohorts, neither the genotype nor the allele frequencies differed significantly between patients and controls. In both luciferase assays, p.R990G showed a significant leftward shift, indicating an increased responsiveness of the receptor. p.A986S showed a leftward shift in the SRE but not in the NFAT reporter assay, while the responsiveness of p.Q1011E did not differ from the wild-type. These functional studies therefore do not support the contributions of variant CASR to increasing the risk of pancreatitis.

CONCLUSIONS

The three frequent CASR polymorphisms are unlikely to increase the risk for chronic pancreatitis.

Sequencing of the complex CTRB1-CTRB2 locus in chronic pancreatitis

BACKGROUND

/Objectives: A recent Genome-wide Association Study (GWAS) in alcoholic chronic pancreatitis (ACP) identified a novel association with the CTRB1-CTRB2 (chymotrypsinogen B1, B2) locus, linked to a 16.6 kb inversion that was confirmed in non-alcoholic chronic pancreatitis (NACP). Moreover, recent findings on the function of CTRB1 and CTRB2 suggest a protective role in pancreatitis development. The aim of the present study was to investigate the CTRB1-CTRB2 locus for rare genetic variants associated with chronic pancreatitis (CP).

METHODS

We analyzed 134 patients with ACP and 203 patients with NACP and compared them to up to 258 healthy controls. Genotyping was performed with polymerase chain reaction, followed by Sanger sequencing of all exons and the exon-intron-boundaries of CTRB1 and CTRB2. Finally, in silico analyses of the identified variants were conducted.

RESULTS

None of the seven rare missense variants or the single 5'-UTR variant in CTRB1 and CTRB2 was associated with ACP or NACP. In silico analysis predicted that variant p. Trp5Leu in CTRB1 and variant c.-4C > T in CTRB2 might alter protein expression and variants p. Asp222His in CTRB1 and p. Ala247Thr in CTRB2 might affect protein function. However, all of these variants were also described in public databases.

CONCLUSIONS

The present study did not reveal an association of rare variants in CTRB1 and CTRB2 with ACP or NACP. Although rare missense variants were almost exclusively found in patients, only four variants were predicted to affect protein expression or function. Thus, a major influence of rare variants in the CTRB1-CTRB2 locus on CP development is unlikely.

Multicenter Study on Differential Human Neutrophil Antigen 2 Expression and Underlying Molecular Mechanisms

Background

The human neutrophil antigen 2 (HNA-2), which is expressed on CD177, is undetectable in 3-5% of the normal population. Exposure of these HNA-2_null individuals to HNA-2-positive cells can cause immunization and pro-duction of HNA-2 antibodies, which can induce immune neutropenia and transfusion-related acute lung injury. In HNA-2-positive individuals, neutrophils are divided into a CD177^pos. and a CD177^neg. subpopulation. The molecular background of HNA-2 deficiency and the bimodal expression pattern, however, are not completely decoded.

Study Design

An international collaboration was conducted on the genetic analysis of HNA-2-phenotyped blood samples, including HNA-2-deficient individuals, mothers, and the respective children with neonatal immune neutropenia and regular blood donors.

Results

From a total of 54 HNA-2_null individuals, 43 were homozygous for the CD177 *787A>T substitution. Six carried the CD177 *c.1291G>A single nucleotide polymorphism. All HNA-2-positive samples with >40% CD177^pos. neutrophils carried the *787A wild-type allele, whereas a lower rate of CD177^pos. neutrophils was preferentially associated with *c.787AT heterozygosity. Interestingly, only the *c.787A allele sequence was detected in complementary DNA (cDNA) sequence analysis carried out on all *c.787AT heterozygous individuals. However, cDNA analysis after sorting of CD177^pos. and CD177^neg. neutrophil subsets from HNA-2-positive individuals showed identical sequences, which makes regulatory elements within the promoter unlikely to affect CD177 gene transcription in different CD177 neutrophil subsets.

Conclusion

This comprehensive study clearly demonstrates the impact of single nucleotide polymorphisms on the expression of HNA-2 on the neutrophil surface but challenges the hypothesis of regulatory epigenetic effects being implicated in the bimodal CD177 expression pattern.

Regulation of ABO blood group antigen expression by miR-331-3p and miR-1908-5p during hematopoietic stem cell differentiation

The ABO blood group system is the most important factor in clinical transfusion medicine and is implicated in a number of human diseases. ABO antigens are not confined to red blood cells (RBCs) and are widely expressed in a variety of human cells and tissues. To date, many alleles with variant ABO expression have been identified and in many cases traced to one of the >250 reported genetic variations in the respective glycosyltransferase. The role of microRNAs (miRNAs) in the regulation of blood group antigens during erythropoiesis has not been addressed, however. Here, we show that miR-331-3p and miR-1908-5p directly target the mRNA of glycosyltransferases A and B. Expression levels of miR-331-3p and miR-1908-5p inversely correlated with levels of blood group A antigen. In addition, we found that overexpression of these miRNAs in hematopoietic stem cells led to a significantly reduced number of blood group A antigens per RBC. Simultaneous targeting of the transcription factor (TF) SP1 by miR-331-3p further enhanced these effects. The targeting rendered SP1 incapable of binding to the ABO gene promoter, causing further downregulation of blood group A antigen expression by up to 70%. Taken together, expression changes in these miRNAs may account for rare cases of weak A/B phenotypes that genetic variations in the glycosyltransferase coding region cannot explain. These results also suggest an explanation for the disappearance of ABH antigens during carcinogenesis and point to new therapeutic targets in ABO mismatched organ transplantation.

Analysis of GPRC6A variants in different pancreatitis etiologies

BACKGROUND

The G-protein-coupled receptor Class C Group 6 Member A (GPRC6A) is activated by multiple ligands and is important for the regulation of calcium homeostasis. Extracellular calcium is capable to increase NLRP3 inflammasome activity of the innate immune system and deletion of this proinflammatory pathway mitigated pancreatitis severity in vivo. As such this pathway and the GPRC6A receptor is a reasonable candidate gene for pancreatitis. Here we investigated the prevalence of sequence variants in the GPRC6A locus in different pancreatitis aetiologies.

METHODS

We selected 6 tagging SNPs with the SNPinfo LD TAG SNP Selection tool and the functional relevant SNP rs6907580 for genotyping. Cohorts from Germany, further European countries and China with up to 1,124 patients and 1,999 controls were screened for single SNPs with melting curve analysis.

RESULTS

We identified an association of rs1606365(G) with alcoholic chronic pancreatitis in a German (odds ratio (OR) 0.76, 95% confidence interval (CI) 0.65-0.89, p = 8 × 10^-5) and a Chinese cohort (OR 0.78, 95% CI 0.64-0.96, p = 0.02). However, this association was not replicated in a combined cohort of European patients (OR 1.18, 95% CI 0.99-1.41, p = 0.07). Finally, no association was found with acute and non-alcoholic chronic pancreatitis.

CONCLUSIONS

Our results support a potential role of calcium sensing receptors and inflammasome activation in alcoholic chronic pancreatitis development. As the functional consequence of the associated variant is unclear, further investigations might elucidate the relevant mechanisms.

TASK-1 channel blockade by AVE1231 increases vasocontractile responses and BP in 1- to 2-week-old but not adult rats

Background and Purpose

The vasomotor role of K2P potassium channels during early postnatal development has never been investigated. We tested the hypothesis that TASK‐1 channel (K2P family member) contribution to arterial vascular tone and BP is higher in the early postnatal period than in adulthood.

Experimental Approach

We studied 10‐ to 15‐day‐old (“young”) and 2‐ to 3‐month‐old (“adult”) male rats performing digital PCR (dPCR) (using endothelium‐intact saphenous arteries), isometric myography, sharp microelectrode technique, quantitative PCR (qPCR) and Western blotting (using endothelium‐denuded saphenous arteries), and arterial pressure measurements under urethane anaesthesia.

Key Results

We found mRNA of Kcnk1–Kcnk7, Kcnk12, and Kcnk13 genes to be expressed in rat saphenous artery, and Kcnk3 (TASK‐1) and Kcnk6 (TWIK‐2) were most abundant in both age groups. The TASK‐1 channel blocker AVE1231 (1 μmol·L⁻¹) prominently depolarized arterial smooth muscle and increased basal tone level and contractile responses to methoxamine of arteries from young rats but had almost no effect in adult rats. The level of TASK‐1 mRNA and protein expression was higher in arteries from young compared with adult rats. Importantly, intravenous administration of AVE1231 (4 mg·kg⁻¹) had no effect on mean arterial pressure in adult rats but prominently raised it in young rats.

Conclusion and Implications

We showed that TASK‐1 channels are important for negative feedback regulation of vasocontraction in young but not adult rats. The influence of TASK‐1 channels most likely contributes to low BP level at perinatal age.

Expression of ADP receptor P2Y12, thromboxane A2 receptor and C-type lectin-like receptor 2 in cord blood-derived megakaryopoiesis

The ADP receptor P2Y₁₂, the thromboxane A₂ receptor (TXA₂R) and the C-type lectin-like receptor 2 (CLEC-2) mediate platelet activation by different mechanisms. Only little is known about the expression of the receptors in human megakaryopoiesis. Our study aimed to establish a flow cytometry (FC) method for the measurement of P2Y₁₂, TXA₂R, and CLEC-2 on platelets of healthy donors and to monitor receptor expression in ex vivo megakaryopoiesis. We determined mean fluorescence intensity (MFI) values of FITC, PE, or APC labeled antibodies binding to the receptors on platelets of 90 healthy donors. For cord blood-derived megakaryopoiesis (CBMK) differentiation of CD34+ cells was induced by IL-3, SCF, and TPO. At 6 time points between day 0 and day 21 of cell culture the MFI values for CD34, CD41, CD61, P2Y₁₂, TXA₂R, and CLEC-2 were measured. Quantitative PCR was used for relative quantification of the corresponding mRNA. Transcription factor (TF) binding sites were predicted by in silico analysis of the genes. Platelets showed expectable high MFI values for the platelet marker CD41 (13,716 median MFI). Lower MFI was found for P2Y₁₂ (2,847 median MFI) and CLEC-2 (1,211 median MFI), whereas, binding of the TXA₂R antibody revealed even higher values (21,458 median MFI) than CD41. In CBMK the CD34+ cells were negative for P2Y₁₂, TXA₂R, and CLEC-2 at day 0. A maximum of 21-fold and 6-fold increase of P2Y₁₂ and TXA₂R MFI values, respectively, was found on day 14 to 17. MFI for CLEC-2 increased by 58-fold within the first week and reached a maximum of 1,572-fold increase within the first two weeks of CBMK. Very similar results were obtained on the RNA level. The differential regulation of receptor expression in CBMK was further supported by significant differences in the numbers and types of TF binding sites. P2Y₁₂ and TXA₂R, both upregulated only to a low extent in CBMK, probably, are dispensable for megakaryopoiesis. Furthermore, we speculate that CLEC-2 strongly upregulated in early CMBK is important for megakaryopoiesis.

Vascular injury biomarkers and stroke risk

Objective

Because little is known about associations between biomarkers of vascular injury and stroke risk, we evaluated associations between plasma concentrations of 6 novel biomarkers of vascular injury and stroke risk in a population-based study.

Methods

A case–cohort subset of EPIC-Heidelberg (European Prospective Investigation for Cancer and Nutrition–Heidelberg) including incident stroke cases (n = 335) and a random subcohort (n = 2,418) was selected. Concentrations of intercellular adhesion molecule 3 (ICAM3), soluble E-selectin and P-selectin, soluble thrombomodulin (sTM), thrombopoietin, and glycoprotein IIb/IIIa were measured in baseline plasma samples. Weighted Cox regression analyses were used to assess associations between biomarker levels and stroke risk.

Results

Median follow-up in the subcohort and among cases was 9.8 (range, 0.1–12.5) years and 6.2 (range, 0.01–12.1) years, respectively. ICAM3 levels were associated with increased risk of incident stroke after multivariable adjustment (hazard ratio, highest vs lowest quartile: 1.64 [95% confidence interval, 1.15–2.32]; plinear trend < 0.001). This association was more apparent for ischemic (1.65 [1.12–2.45]; plinear trend < 0.01) than for hemorrhagic stroke (1.29 [0.60–2.78]; plinear trend = 0.3). We further observed a borderline significant trend for a positive association between sTM and overall stroke risk (1.47 [0.99–2.19]; plinear trend = 0.05).

Conclusions

In this population-based study, circulating levels of ICAM3, an adhesion molecule shed by leukocytes, were associated with increased risk of incident stroke. Further mechanistic studies are needed to elucidate the pathophysiology underlying this association.

Classification of evidence

This study provides Class II evidence that plasma levels of ICAM3 are associated with increased stroke risk.

Variants That Affect Function of Calcium Channel TRPV6 Are Associated With Early-Onset Chronic Pancreatitis

BACKGROUND & AIMS

Changes in pancreatic calcium levels affect secretion and might be involved in development of chronic pancreatitis (CP). We investigated the association of CP with the transient receptor potential cation channel subfamily V member 6 gene (TRPV6), which encodes a Ca²⁺-selective ion channel, in an international cohort of patients and in mice.

METHODS

We performed whole-exome DNA sequencing from a patient with idiopathic CP and from his parents, who did not have CP. We validated our findings by sequencing DNA from 300 patients with CP (not associated with alcohol consumption) and 1070 persons from the general population in Japan (control individuals). In replication studies, we sequenced DNA from patients with early-onset CP (20 years or younger) not associated with alcohol consumption from France (n = 470) and Germany (n = 410). We expressed TRPV6 variants in HEK293 cells and measured their activity using Ca²⁺ imaging assays. CP was induced by repeated injections of cerulein in TRPV6^mut/mut mice.

RESULTS

We identified the variants c.629C>T (p.A210V) and c.970G>A (p.D324N) in TRPV6 in the index patient. Variants that affected function of the TRPV6 product were found in 13 of 300 patients (4.3%) and 1 of 1070 control individuals (0.1%) from Japan (odds ratio [OR], 48.4; 95% confidence interval [CI], 6.3-371.7; P = 2.4 × 10^-8). Twelve of 124 patients (9.7%) with early-onset CP had such variants. In the replication set from Europe, 18 patients with CP (2.0%) carried variants that affected the function of the TRPV6 product compared with 0 control individuals (P = 6.2 × 10^-8). Variants that did not affect the function of the TRPV6 product (p.I223T and p.D324N) were overrepresented in Japanese patients vs control individuals (OR, 10.9; 95% CI, 4.5-25.9; P = 7.4 × 10^-9 for p.I223T and P = .01 for p.D324N), whereas the p.L299Q was overrepresented in European patients vs control individuals (OR, 3.0; 95% CI, 1.9-4.8; P = 1.2 × 10^-5). TRPV6^mut/mut mice given cerulein developed more severe pancreatitis than control mice, as shown by increased levels of pancreatic enzymes, histologic alterations, and pancreatic fibrosis.

CONCLUSIONS

We found that patients with early-onset CP not associated with alcohol consumption carry variants in TRPV6 that affect the function of its product, perhaps by altering Ca²⁺ balance in pancreatic cells. TRPV6 regulates Ca²⁺ homeostasis and pancreatic inflammation.

Serum levels of advanced glycation end products and their receptors sRAGE and Galectin-3 in chronic pancreatitis

BACKGROUND

/Objectives: AGE and their receptors like RAGE and Galectin-3 can activate inflammatory pathways and have been associated with chronic inflammatory diseases. Several studies investigated the role of AGE, Galectin-3 and sRAGE in pancreatic diseases, whereas no comprehensive data for chronic pancreatitis (CP) are available.

METHODS

Serum samples from CP patients without an active inflammatory process (85 ACP; 26 NACP patients) and 40 healthy controls were collected. Levels of AGE, sRAGE and Galectin-3 were measured by ELISA. To exclude potential influences of previously described RAGE SNPs on detected serum levels, we analyzed variants rs207128, rs207060, rs1800625, and rs1800624 by melting curve technique in 378 CP patients and 338 controls.

RESULTS

AGE and Galectin-3 serum levels were significantly elevated in both ACP and NACP patients compared to controls (AGE: 56.61 ± 3.043 vs. 31.71 ± 2.308 ng/mL; p < 0.001; Galectin-3: 16.63 ± 0.6297 vs. 10.81 ± 0.4835 ng/mL; p < 0.001). In contrast, mean serum sRAGE levels were significantly reduced in CP patients compared to controls (sRAGE: 829.7 ± 37.10 vs. 1135 ± 55.74 ng/mL; p < 0.001). All results were consistent after correction for gender, age and diabetes mellitus. No genetic association with CP was found.

CONCLUSIONS

Our extensive analysis demonstrated the importance of aging related pathways in the pathogenesis of CP. As the results were consistent in ACP and NACP, both entities most likely share common pathomechanisms. Most probably the involved pathways are a general hallmark of an inflammatory state in CP that is even present in symptom-free intervals.

Introduction of Noninvasive Prenatal Testing for Blood Group and Platelet Antigens from Cell-Free Plasma DNA Using Digital PCR

Background

Noninvasive prenatal testing (NIPT) for fetal antigens is a common standard for targeted immune prophylaxis in RhD-mediated hemolytic disease of the fetus and newborn, and is most frequently done by quantitative PCR (qPCR). A similar approach is considered for other blood group and human platelet alloantigens (HPA). Because of a higher sensitivity compared to qPCR for rare molecule detection, we established and validated digital PCR (dPCR) assays for the detection of RHD exons 3, 5 and 7, KEL1, HPA-1a, and HPA-5b from cell-free DNA (cfDNA) in plasma. The dPCR assays for the Y-chromosomal marker amelogenin and autosomal SNPs were implemented as controls for the proof of fetal DNA.

Methods

Validation was performed on dilution series of mixed plasma samples from volunteer donors with known genotypes. After preamplification of the target loci, two-color (FAM and VIC) TaqMan^TM probe chemistry and chip-based dPCR were applied. The assays for RHD included GAPDH as an internal control. For the diallelic markers KEL1/2, HPA-1a/b, HPA-5a/b, and AMEL-X/Y and 3 autosomal SNPs, the probes enabled allelic discrimination in the two fluorescence channels. The dPCR protocol for NIPT was applied to plasma samples from pregnant women.

Results

The RHD exon 5 assay allowed the detection of a 0.05% RHD target in an RhD-negative background, whereas the exon 7 assay required at least a 0.25% target. The exon 3 assay showed the highest background and required at least a 2.5% RHD target for reliable detection. The dPCR assays for the diallelic markers revealed similar sensitivity and enabled the detection of at least a 0.5% target allele. The HPA-1a assay was the most sensitive and allowed target detection in plasma mixtures containing only 0.05% HPA-1a. The plasma samples from 13 pregnant women at different gestational ages showed unambiguous positive and negative results for the analyzed targets.

Conclusion

Analysis of cfDNA from maternal plasma using dPCR is suitable for the detection of fetal alleles. Because of the high sensitivity of the assays, the NIPT protocol for RhD, KEL1, and HPA can also be applied to earlier stages of pregnancy.

Common variants in glyoxalase I do not increase chronic pancreatitis risk

Introduction

Chronic pancreatitis (CP) may be caused by oxidative stress. An important source of reactive oxygen species (ROS) is the methylglyoxal-derived formation of advanced glycation endproducts (AGE). Methylglyoxal is detoxified by Glyoxalase I (GLO1). A reduction in GLO1 activity results in increased ROS. Single nucleotide polymorphisms (SNPs) of GLO1 have been linked to various inflammatory diseases. Here, we analyzed whether common GLO1 variants are associated with alcoholic (ACP) and non-alcoholic CP (NACP).

Methods

Using melting curve analysis, we genotyped a screening cohort of 223 ACP, 218 NACP patients, and 328 controls for 11 tagging SNPs defined by the SNPinfo LD TAG SNP Selection tool and the functionally relevant variant rs4746. For selected variants the cohorts were extended to up to 1,441 patient samples.

Results

In the ACP cohort, comparison of genotypes for rs1937780 between patients and controls displayed an ambiguous result in the screening cohort (p = 0.08). However, in the extended cohort of 1,441 patients no statistically significant association was found for the comparison of genotypes (p = 0.11), nor in logistic regression analysis (p = 0.214, OR 1.072, 95% CI 0.961–1.196). In the NACP screening cohort SNPs rs937662, rs1699012, and rs4746 displayed an ambiguous result when patients were compared to controls in the recessive or dominant model (p = 0.08, 0.08, and 0.07, respectively). Again, these associations were not confirmed in the extended cohorts (rs937662, dominant model: p = 0.07, logistic regression: p = 0.07, OR 1.207, 95% CI 0.985–1.480) or in the replication cohorts for rs4746 (Germany, p = 0.42, OR 1.080, 95% CI 0.673–1.124; France, p = 0.19, OR 0.90, 95% CI 0.76–1.06; China, p = 0.24, OR 1.18, 95% CI 0.90–1.54) and rs1699012 (Germany, Munich; p = 0.279, OR 0.903, 95% CI 0.750–1.087).

Conclusions

Common GLO1 variants do not increase chronic pancreatitis risk.

Thrombomodulin and Thrombopoietin, Two Biomarkers of Hemostasis, Are Positively Associated with Adherence to the World Cancer Research Fund/American Institute for Cancer Research Recommendations for Cancer Prevention in a Population-Based Cross-Sectional Study

A pro-coagulative state is related to increased risk of cardiovascular diseases but also certain cancers. Since experimental and smaller human studies suggest that diet, physical activity, and body weight may all affect coagulation, we evaluated associations between these lifestyle factors and hemostatic biomarkers in a population-based study. Cross-sectional baseline data from 2267 randomly selected participants of EPIC-Heidelberg (age range 35–65 years) was used. Fibrinogen, glycoprotein IIb/IIIa, P-selectin, thrombomodulin (TM), and thrombopoietin (TPO) were measured in baseline plasma samples. A score reflecting adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommendations for cancer prevention was created. Associations between the WCRF/AICR score as well as its individual components and hemostatic biomarkers were analyzed by linear regression models. Multivariable-adjusted geometric means (95% confidence intervals) of TM and TPO were higher with greater adherence to the WCRF/AICR recommendations (TM, lowest vs. highest score category: 2.90 (2.7,3.1) vs. 3.10 (2.9,3.3) ng/mL, p_{linear trend} = 0.0001; TPO: 328 (302,356) vs. 348 (321,378) pg/mL, p_{linear trend} = 0.0007). These associations were driven by lower alcohol and meat consumption among persons with higher WCRF/AICR scores. Our results indicate that lifestyle factors favorably affect TM and TPO, two hemostatic factors implicated in chronic disease development.

Multivariate Platelet Analysis Differentiates Between Patients with Alzheimer's Disease and Healthy Controls at First Clinical Diagnosis

BACKGROUND

Early diagnosis of Alzheimer's disease (AD) is challenging, and easily accessible biomarkers are an unmet need. Blood platelets frequently serve as peripheral model for studying AD pathogenesis and might represent a reasonable biomarker source.

OBJECTIVE

In the present study, we investigated the potential to differentiate AD patients from healthy controls (HC) based on blood count, platelet morphology, and function as well as molecular markers at the time of first clinical diagnosis.

METHODS

Blood samples from 40 AD patients and 29 age-matched HC were included for determination of 78 parameter by blood counting, platelet morphometry, aggregometry, flow cytometry (CD62P, CD63, activated fibrinogen receptor), protein quantification of nicotinic acetylcholine receptor α7 (nAChRα7) and caveolin-1 (CAV-1), and miRNA quantification (miR-26b, miR-199a, miR-335). Group comparison between patients and controls was performed in univariate and multivariate statistical analyses.

RESULTS

AD patients showed significantly lower aggregation response to ADP and arachidonic acid and significantly decreased CD62P and CD63 surface expression induced by ADP and U46619 compared to HC. Relative nAChRα7 and CAV-1 expression was significantly higher AD platelets than in HC. Multivariate analysis of 63 parameter revealed significant differences between AD patients and healthy controls. The best performing feature model revealed a sensitivity of 96.6%, a specificity of 80.0%, and a positive predictive value of 89.3%. No grouping could be achieved by using single parameter groups.

CONCLUSION

Significant differences between platelet characteristics from AD patients and HC at the time of first clinical diagnosis were observed. The best performing parameter can be used as a blood-based biomarker for AD diagnosis in a multivariate model in addition to the standardized mental tests.

An update on the H blood group system

This update of the H blood group system (Scharberg EA, Olsen C, Bugert P. The H blood group system. Immunohematology 2016;32:112-8) reports 11 new FUT1 null alleles: 8 causative for the H- phenotype (Bombay phenotype, Oh), 3 in para-Bombay cases, and 5 new FUT1 alleles causative for a weak H phenotype (para-Bombay, H+w). The H blood group system (International Society of Blood Transfusion system 18) consists of a single antigen (H) defined by a terminal fucose residue found on red blood cells (RBCs) and in secretions. The H antigen is synthesized on the RBC surface by the FUT1 gene product fucosyltransferase 1. On epithelial cells and in body fluids, the H antigen is synthesized by the FUT2 gene product fucosyltransferase 2.

Use of Targeted High-Throughput Sequencing for Genetic Classification of Patients with Bleeding Diathesis and Suspected Platelet Disorder

Inherited platelet disorders (IPD) form a rare and heterogeneous disease entity that is present in about 8% of patients with non-acquired bleeding diathesis. Identification of the defective cellular pathway is an important criterion for stratifying the patient's individual risk profile and for choosing personalized therapeutic options. While costs of high-throughput sequencing technologies have rapidly declined over the last decade, molecular genetic diagnosis of bleeding and platelet disorders is getting more and more suitable within the diagnostic algorithms. In this study, we developed, verified, and evaluated a targeted, panel-based next-generation sequencing approach comprising 59 genes associated with IPD for a cohort of 38 patients with a history of recurrent bleeding episodes and functionally suspected, but so far genetically undefined IPD. DNA samples from five patients with genetically defined IPD with disease-causing variants in WAS , RBM8A , FERMT3 , P2YR12 , and MYH9 served as controls during the validation process. In 40% of 35 patients analyzed, we were able to finally detect 15 variants, eight of which were novel, in 11 genes, ACTN1 , AP3B1 , GFI1B , HPS1 , HPS4 , HPS6 , MPL , MYH9 , TBXA2R , TPM4 , and TUBB1 , and classified them according to current guidelines. Apart from seven variants of uncertain significance in 11% of patients, nine variants were classified as likely pathogenic or pathogenic providing a molecular diagnosis for 26% of patients. This report also emphasizes on potentials and pitfalls of this tool and prospectively proposes its rational implementation within the diagnostic algorithms of IPD.

Evaluation of Diagnostic Tests by Evanescence Biosensor Technology for Rapid Phenotyping of the Human Platelet Alloantigens 1a and 5b

Background

The human platelet alloantigens (HPA) HPA-1a and HPA-5b are located on glycoproteins on the platelet surface and are the most relevant to cause neonatal alloimmune thrombocytopenia (NAIT). The antigens are defined by single nucleotide polymorphisms (SNPs) in the glycoprotein genes, and the antigen status can be determined by genotyping the SNPs. However, genotyping is time-consuming and costly depending on the method and sample throughput. Here, we tested the reliability of the evanescence wave based fluorescence (EVA) biosensor technology for the rapid phenotyping of the HPA-1a and HPA-5b antigens on blood donor samples in two laboratories.

Methods

HPA-1a and HPA-5b phenotyping was performed on EDTA blood samples from 336 blood donors (Lyon: 216 donors; Mannheim: 120 donors) using EVA typing assays and the biosensor system (Davos Diagnostics, Davos, Switzerland). For genotyping, validated PCR-SSP and TaqMan-PCR methods were used.

Results

HPA-1a phenotyping was positive for all samples with HPA-1aa (n = 244; EVA value 807 ± 167 U/s) and HPA-1ab (n = 82; 542 ± 110 U/s) genotypes. All samples (n = 10) with negative EVA values (<10 U/s) had the HPA-1bb genotype. HPA-5b phenotyping was negative for all HPA-5aa genotypes (n = 267) and positive for the HPA-5ab (n = 66; 83 ± 22 U/s) and HPA-5bb (n = 3; 118 ± 25 U/s) genotypes. EVA values from heterozygotes were significantly lower compared to HPA-1a or HPA-5b homozygotes. A strong correlation of the EVA values with the platelet count in the blood samples was observed.

Conclusion

EVA is a reliable method for rapid phenotyping of the clinically relevant HPA-1a and HPA-5b platelet antigens. All phenotyping results were 100% concordant with the HPA-1 or HPA-5 genotype. The test can be performed from only 10 µl of fresh or frozen blood samples within less than 15 min time-to-result.

Towards a Regional Registry of Extended Typed Blood Donors: Molecular Typing for Blood Group, Platelet and Granulocyte Antigens

BACKGROUND

The provision of compatible blood products to patients is the most essential task of transfusion medicine. Besides ABO and Rh, a number of additional blood group antigens often have to be considered for the blood supply of immunized or chronically transfused patients. It also applies for platelet antigens (HPA) and neutrophil antigens (HNA) for patients receiving platelet or granulocyte concentrates. Here, we describe the molecular screening for a number of blood group, HPA, and HNA alleles. Based on the screening results we are building up a regional blood donor registry to provide extended matched blood products on demand.

METHODS

We developed and validated TaqMan™ PCR and PCR-SSP methods for genetic markers defining 37 clinically relevant blood group antigens (beyond ABO and Rh), 10 HPA, and 11 HNA. Furthermore, we describe a feasible method for fast molecular screening of the HNA-2null phenotype. All data were statistically evaluated regarding genotype distribution. Allele frequencies were compared to ExAC data from non-Finnish Europeans.

RESULTS

Up to now more than 2,000 non-selected regular blood donors in south-west Germany have been screened for blood group, HPA, and HNA alleles. The screening results were confirmed by serology and PCR-SSP methods for selected numbers of samples. The allele frequencies were similar to non-finnish Europeans in the ExAC database except for the alleles encoding the S, HPA-3b and HNA-4b antigens, with significantly lower prevalence in our cohort, as well as the LU14 and the HNA-3b antigens, with a higher frequency compared to the ExAC data. We identified 71 donors with rare blood groups such as Lu(a+b-), Kp(a+b-), Fy(a-b-) and Vel-, and 169 donors with less prevalent HPA or HNA types.

CONCLUSION

Molecular screening for blood group alleles by using TaqMan™ PCR is an effective and reliable high-throughput method for establishing a rare donor registry.

Genome-wide association study identifies inversion in the CTRB1-CTRB2 locus to modify risk for alcoholic and non-alcoholic chronic pancreatitis

OBJECTIVE

Alcohol-related pancreatitis is associated with a disproportionately large number of hospitalisations among GI disorders. Despite its clinical importance, genetic susceptibility to alcoholic chronic pancreatitis (CP) is poorly characterised. To identify risk genes for alcoholic CP and to evaluate their relevance in non-alcoholic CP, we performed a genome-wide association study and functional characterisation of a new pancreatitis locus.

DESIGN

1959 European alcoholic CP patients and population-based controls from the KORA, LIFE and INCIPE studies (n=4708) as well as chronic alcoholics from the GESGA consortium (n=1332) were screened with Illumina technology. For replication, three European cohorts comprising 1650 patients with non-alcoholic CP and 6695 controls originating from the same countries were used.

RESULTS

We replicated previously reported risk loci CLDN2-MORC4, CTRC, PRSS1-PRSS2 and SPINK1 in alcoholic CP patients. We identified CTRB1-CTRB2 (chymotrypsin B1 and B2) as a new risk locus with lead single-nucleotide polymorphism (SNP) rs8055167 (OR 1.35, 95% CI 1.23 to 1.6). We found that a 16.6 kb inversion in the CTRB1-CTRB2 locus was in linkage disequilibrium with the CP-associated SNPs and was best tagged by rs8048956. The association was replicated in three independent European non-alcoholic CP cohorts of 1650 patients and 6695 controls (OR 1.62, 95% CI 1.42 to 1.86). The inversion changes the expression ratio of the CTRB1 and CTRB2 isoforms and thereby affects protective trypsinogen degradation and ultimately pancreatitis risk.

CONCLUSION

An inversion in the CTRB1-CTRB2 locus modifies risk for alcoholic and non-alcoholic CP indicating that common pathomechanisms are involved in these inflammatory disorders.

The Impact of Using Genotyped Reagent Red Blood Cells in Antibody Identification

Background

The detection and identification of antibodies to red blood cell (RBC) antigens is one of the most important and challenging issues in transfusion medicine. Up to date there are 354 RBC antigens recognized by the International Society of Blood Transfusion (ISBT). The reagent RBCs used in commercial antibody screening and identification panels however are usually serologically typed for up to 40 clinically important antigens. Thus the identification of many antibody specificities remains impossible when using reagent RBCs with only limited information about their antigens. To improve the pre-transfusion diagnostics, we developed antibody identification panels with reagent RBCs serologically typed for 26 antigens and additionally genotyped for 30 blood group alleles.

Methods

The reagent RBCs in the panels were characterized serologically for the clinically most significant 'standard' antigens. The reagent RBC donors were additionally genotyped by using in-house PCR-SSP methods. The antibody identification was performed in the indirect antiglobulin test using untreated and papain-treated RBCs in the gel technique. Antibodies identified due to the genotype information were confirmed by serology using appropriate reference RBCs.

Results

Within a time period of 3 years and 8 months, 16,878 blood samples from 8,467 patients were tested in our reference laboratory. In total, 21 different antibodies from 10 different blood group systems could be identified in 126 patients (1.5%) due to the genotype information obtained for the reagent RBCs. Antibodies to antigens from the Knops system (53 patients; 42%, 8 patients with anti-Kn^b) and to Cartwright antigens (31 patients; 25%) were the most frequent.

Conclusion

The use of genotyped reagent RBCs in antibody identification panels extends the range of detectable antibody specificities, accelerates the antibody identification, and improves the pre-transfusion diagnostics.

Human mesenchymal stromal cells inhibit platelet activation and aggregation involving CD73-converted adenosine

Background

Mesenchymal stromal cells (MSCs) are promising cell therapy candidates. Clinical application is considered safe. However, minor side effects have included thromboembolism and instant blood-mediated inflammatory reactions suggesting an effect of MSC infusion on hemostasis. Previous studies focusing on plasmatic coagulation as a secondary hemostasis step detected both procoagulatory and anticoagulatory activities of MSCs. We now focus on primary hemostasis and analyzed whether MSCs can promote or inhibit platelet activation.

Methods

Effects of MSCs and MSC supernatant on platelet activation and function were studied using flow cytometry and further platelet function analyses. MSCs from bone marrow (BM), lipoaspirate (LA) and cord blood (CB) were compared to human umbilical vein endothelial cells or HeLa tumor cells as inhibitory or activating cells, respectively.

Results

BM-MSCs and LA-MSCs inhibited activation and aggregation of stimulated platelets independent of the agonist used. This inhibitory effect was confirmed in diagnostic point-of-care platelet function analyses in platelet-rich plasma and whole blood. Using inhibitors of the CD39–CD73–adenosine axis, we showed that adenosine produced by CD73 ectonucleotidase activity was largely responsible for the LA-MSC and BM-MSC platelet inhibitory action. With CB-MSCs, batch-dependent responses were obvious, with some batches exerting inhibition and others lacking this effect.

Conclusions

Studies focusing on plasmatic coagulation suggested both procoagulatory and anticoagulatory activities of MSCs. We now show that MSCs can, dependent on their tissue origin, inhibit platelet activation involving adenosine converted from adenosine monophosphate by CD73 ectonucleotidase activity. These data may have strong implications for safety and risk/benefit assessment regarding MSCs from different tissue sources and may help to explain the tissue protective mode of action of MSCs. The adenosinergic pathway emerges as a key mechanism by which MSCs exert hemostatic and immunomodulatory functions.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0936-8) contains supplementary material, which is available to authorized users.

Granulocyte antibodies in male blood donors: can they trigger transfusion-related acute lung injury?

BACKGROUND

White blood cell-associated antibodies can lead to transfusion-related acute lung injury (TRALI). Female donors with a history of pregnancies have been identified as a main cause for these antibodies. Male or female donors without a history of pregnancy are considered as safe donors.

STUDY DESIGN AND METHODS

Following the identification of two TRALI cases associated with blood products from male donors, we investigated the frequency of granulocyte-specific and human leukocyte antigen (HLA) antibodies in the entire blood donor population using a high throughput automated flow-cytometry-based granulocyte immunofluorescence test (Flow-GIFT). We investigated sera from 14,343 whole blood donors (female, n = 6974, 48.7%; male, n = 7369, 51.3%) using automated Flow-GIFT. Of the female blood donors, 60.4% had a history of pregnancy. Positive sera were retested by the standard granulocyte immunofluorescence test and granulocyte agglutination test. For the detection of HLA Class I and II immunoglobulin G antibodies, we used a commercial screening enzyme-linked immunosorbent assay.

RESULTS

We detected in 924 (21.9%) of the 4212 females with a history of pregnancy antibodies against granulocyte antigens (n = 62, 1.5%), HLA Class I and/or II antigens (n = 864, 20.5%). Notably, in 3.5% (n = 96) of 2762 females without a history of pregnancy and in 2.1% (n = 154) of 7369 males antibodies against granulocyte antigens (n = 13, 0.47% and n = 45, 0.6%), HLA Class I and/or II (n = 83, 3% and n = 109, 1.4%, respectively), were also detected.

CONCLUSION

Human neutrophil antigen antibodies are rare in male and females without a history of pregnancy compared to females with a history of pregnancy, but their relevance is not negligible.

Clinical and laboratory aspects of the Aspirin-like defect as hereditary thrombocytopathy

The Aspirin-like defect (ALD) is caused by defects in the intraplatelet arachidonic acid (AA)-metabolism. We here present the characteristics of a larger cohort in a single centre. Patients, methods: Based on 17 ALD index patients bleeding symptoms, agonist-induced platelet aggregation and closure times in the PFA-100® test were analysed in a family cohort of altogether 52 individuals from 17 families. Absent aggregation to AA (maximal aggregation ≤10%) was the main diagnostic criterion. A mild ALD was diagnosed when aggregation was 11–40%. Results: In addition to 17 ALD index patients, 13 family members displayed ALD. 4 family members were diagnosed with a mild ALD. Epistaxis, easy bruising, menorrhagia and perioperative hemorrhage were the most common bleeding symptoms, whereas three quarters of ALD patients presented with ≥ 1 bleeding symptoms. Conclusion: In case of a bleeding tendency diagnostic procedures should rule out primary haemostatic defects. Hereditary platelet function defects including ALD are an important differential diagnosis. Family studies are reasonable.