Impact of the pre-examination phase on multicenter metabolomic studies

The development of metabolomics in clinical applications has been limited by the lack of validation in large multicenter studies. Large population cohorts and their biobanks are a valuable resource for acquiring insights into molecular disease mechanisms. Nevertheless, most of their collections are not tailored for metabolomics and have been created without specific attention to the pre-analytical requirements for high-quality metabolome assessment. Thus, comparing samples obtained by different pre-analytical procedures remains a major challenge. Here, ¹H NMR-based analyses are used to demonstrate how human serum and plasma samples collected with different operating procedures within several large European cohort studies from the Biobanking and Biomolecular Resources Infrastructure - Large Prospective Cohorts (BBMRI-LPC) consortium can be easily revealed by supervised multivariate statistical analyses at the initial stages of the process, to avoid biases in the downstream analysis. The inter-biobank differences are discussed in terms of deviations from the validated CEN/TS 16945:2016 / ISO 23118:2021 norms. It clearly emerges that biobanks must adhere to the evidence-based guidelines in order to support wider-scale application of metabolomics in biomedicine, and that NMR spectroscopy is informative in comparing the quality of different sample sources in multi cohort/center studies.

Cardiovascular risk and metabolic profile of Polish citizens from Lower Silesia. First signs of metabolic crisis?

Introduction

Population biobanks are essential for the development of public health screening and improvement of personalized medicine. Since 2012, Biobank of Łukasiewicz Research Network - PORT Polish Center for Technology Development (PORT Biobank) has collected more than 120 000 biological samples from nearly 5000 inhabitants of Lower Silesia, together with a variety of demographic, anthropometric, life style and health information.

Material and methods

The analyzed group consisted of 2274 participants (1398 women, 876 men). Both women and men were further subdivided into five age decades (20+, 30+, 40+, 50+, 60+). For this study, the level of lipids (total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides) was estimated and correlated with the level of high-sensitivity C-reactive protein (hs-CRP) and biometric parameters.

Results

We have demonstrated for the first time that biochemical changes that may lead to cardiovascular diseases (CVD) occurred already in the group of people aged 30+. Our observation is based on measurements of lipids, glucose, inflammatory (hs-CRP) and biometric markers such as body mass index (BMI) and waist-to-hip ratio (WHR).

Conclusions

Positive correlations with age for these variables suggest the ongoing progress of metabolic changes, which in the end may lead to a fatal outcome such as myocardial infarction or stroke. It suggests that CVD screening programs should be dedicated to a wider group, especially younger citizens, in order to prevent fatal outcomes related to CVD.

Immunoaffinity Targeted Mass Spectrometry Analysis of Human Plasma Samples Reveals an Imbalance of Active and Inactive CXCL10 in Primary Sjögren's Syndrome Disease Patients

One of the most important advantages of mass spectrometry is the ability to quantify proteins and their modifications in parallel to obtain a holistic picture of the protein of interest. Here, we present a hybrid immunoaffinity targeted mass spectrometry (MS) method that combines efficient pan-antibody enrichment of a specific protein from plasma with the selectivity of high-resolution targeted MS analysis to quantitate specific proteoforms of interest. We used this approach to quantify plasma levels of the chemokine CXCL10 that has been associated with many immunological disorders such as systemic lupus erythematosus and primary Sjögren's Syndrome (pSS). The hybrid approach enabled sensitive, specific, and simultaneous quantification of total, full-length (active) CXCL10_1-77 and DPP4-truncated (inactive) CXCL10_3-77 in human plasma down to the low pg/mL level, reaching ELISA sensitivities. Samples from 30 control subjects and 34 pSS patients (n = 64) were analyzed. The ratio of CXCL10_1-77 to truncated CXCL10_3-77 was significantly increased in patients with pSS and provided the highest correlation with pSS disease activity. Therefore, this CXCL10 proteoform ratio represents an interesting exploratory disease activity biomarker to further investigate. As this strategy can be readily adapted to other plasma proteins and proteoforms of interest, we are convinced that it will lead to a more detailed understanding of proteoforms in physiology and pathology yielding more relevant biomarkers and drug targets.

BBMRI-ERIC's contributions to research and knowledge exchange on COVID-19

During the COVID-19 pandemic, the European biobanking infrastructure is in a unique position to preserve valuable biological material complemented with detailed data for future research purposes. Biobanks can be either integrated into healthcare, where preservation of the biological material is a fork in clinical routine diagnostics and medical treatment processes or they can also host prospective cohorts or material related to clinical trials. The paper discussed objectives of BBMRI-ERIC, the European research infrastructure established to facilitate access to quality-defined biological materials and data for research purposes, with respect to the COVID-19 crisis: (a) to collect information on available European as well as non-European COVID-19-relevant biobanking resources in BBMRI-ERIC Directory and to facilitate access to these via BBMRI-ERIC Negotiator platform; (b) to help harmonizing guidelines on how data and biological material is to be collected to maximize utility for future research, including large-scale data processing in artificial intelligence, by participating in activities such as COVID-19 Host Genetics Initiative; (c) to minimize risks for all involved parties dealing with (potentially) infectious material by developing recommendations and guidelines; (d) to provide a European-wide platform of exchange in relation to ethical, legal, and societal issues (ELSI) specific to the collection of biological material and data during the COVID-19 pandemic.

Improvement in insulin resistance is greater when infliximab is added to methotrexate during intensive treatment of early rheumatoid arthritis-results from the IDEA study

OBJECTIVES

To determine the change in established biomarkers of cardiovascular (CV) risk, namely, total cholesterol/high-density lipoprotein cholesterol ratio (TC/HDL-C), N-terminal pro-brain natriuretic peptide (NT-proBNP) and insulin resistance (IR) in patients with early RA treated with two different treat-to-target strategies.

METHODS

Fasting glucose, lipids, insulin and NT-proBNP were measured at baseline, weeks 26 and 78 in 79 DMARD-naïve RA patients, free of CV disease, as part of a double-blind randomized controlled trial of MTX with either infliximab (IFX) or methylprednisolone as induction therapy. Homeostasis model assessment-estimated IR (HOMA-IR) (glucose*insulin/405) was used to measure IR. Multiple imputation was employed, and linear regression analyses were adjusted for baseline values.

RESULTS

Changes in DAS44-CRP did not differ between the treatment arms at weeks 26 and 78. Mean TC/HDL-C, HOMA-IR and NT-proBNP improved in both groups at weeks 26 and 78, although change in NT-proBNP was not statistically significant at week 78. Changes in TC/HDL-C and NT-proBNP were similar between treatment arms, but HOMA-IR values in the IFX + MTX arm were 42% lower than those treated with MTX + methylprednisolone at week 78 (P = 0.003); the difference remained significant after adjustment for baseline BMI, ACPA positivity, smoking status and intramuscular glucocorticoid use (P = 0.007).

CONCLUSION

When implementing a treat-to-target approach, treatment of early RA was associated with improvement in TC/HDL-C, HOMA-IR and NT-proBNP, and a greater long-term improvement in HOMA-IR was seen in those treated with IFX.

TRIAL REGISTRATION

EU Clinical Trials Register, http://www.clinicaltrialsregister.eu, Eudract-2005-005013-37; ISRTCNregisrty, http://www.isrctn.com, ISRCTN48638981.

Caveolae act as membrane reserves which limit mechanosensitive I(Cl,swell) channel activation during swelling in the rat ventricular myocyte

Background

Many ion channels are preferentially located in caveolae where compartmentalisation/scaffolding with signal transduction components regulates their activity. Channels that are mechanosensitive may be additionally dependent on caveolar control of the mechanical state of the membrane. Here we test which mechanism underlies caveolar-regulation of the mechanosensitive I_Cl,swell channel in the adult cardiac myocyte.

Methodology/Principal Findings

Rat ventricular myocytes were exposed to solution of 0.02 tonicity (T; until lysis), 0.64T for 10–15 min (swelling), and/or methyl-β-cyclodextrin (MBCD; to disrupt caveolae). MBCD and 0.64T swelling reduced the number of caveolae visualised by electron microscopy by 75 and 50% respectively. MBCD stimulated translocation of caveolin 3 from caveolae-enriched buoyant membrane fractions, but both caveolin 1 and 3 remained in buoyant fractions after swelling. I_Cl,swell inhibition in control cells decreased time to half-maximal volume (t_0.5,vol; 0.64T), consistent with a role for I_Cl,swell in volume regulation. MBCD-treated cells showed reduced time to lysis (0.02T) and t_0.5,vol (0.64T) compared with controls. The negative inotropic response to swelling (an index of I_Cl,swell activation) was enhanced by MBCD.

Conclusions/Significance

These data show that disrupting caveolae removes essential membrane reserves, which speeds swelling in hyposmotic conditions, and thereby promotes activation of I_Cl,swell. They illustrate a general principle whereby caveolae as a membrane reserve limit increases in membrane tension during stretch/swelling thereby restricting mechanosensitive channel activation.

Compartmentalisation of cAMP-dependent signalling by caveolae in the adult cardiac myocyte

Cyclic AMP exhibits local (sarcolemmal) and global (cytosolic) patterns of signalling, allowing receptor-specific signals to be generated by a single second messenger. Here we determine whether caveolae, invaginated lipid rafts, are responsible for confining the beta(2) adrenoceptor (AR) cAMP signal to the sarcolemmal compartment. Myocytes were treated with the cholesterol-depleting agent methyl-beta-cyclodextrin (M beta C) to disrupt caveolae. Caveolae-containing membrane fractions were isolated by detergent-free sucrose gradient fractionation. Cell shortening and phosphorylation of the sarcoplasmic reticular protein phospholamban (PLB) and the myofilament protein troponin I (TnI) were measured in response to beta(2) AR stimulation (with salbutamol in the presence of 1 microM atenolol). Ser(16) phosphorylation of PLB (pPLB), Ser(22,23) phosphorylation of TnI (pTnI), and positive lusitropy were used as indices of global cAMP signals. The ability of M beta C to disrupt caveolae was confirmed by selective depletion of the buoyant membrane fractions of cholesterol and caveolin 3, the 2 essential components of caveolae. In control cells, no change in pPLB, pTnI or time to half relaxation was recorded with beta(2) AR stimulation (P>0.05), but following caveolar disruption a 60-70% increase in phosphorylation of both proteins was seen, accompanied by positive lusitropy (P<0.05). These data show for the first time that disrupting caveolae converts the sarcolemmal-confined cAMP signal associated with beta(2) AR stimulation to a global signal that targets proteins of the sarcoplasmic reticulum and myofilaments, with functional sequelae. The role of caveolae in spatial control of cAMP may be relevant to perturbation of beta AR signalling in cardiovascular disease.

The repressor element 1-silencing transcription factor regulates heart-specific gene expression using multiple chromatin-modifying complexes

Cardiac hypertrophy is associated with a dramatic change in the gene expression profile of cardiac myocytes. Many genes important during development of the fetal heart but repressed in the adult tissue are reexpressed, resulting in gross physiological changes that lead to arrhythmias, cardiac failure, and sudden death. One transcription factor thought to be important in repressing the expression of fetal genes in the adult heart is the transcriptional repressor REST (repressor element 1-silencing transcription factor). Although REST has been shown to repress several fetal cardiac genes and inhibition of REST function is sufficient to induce cardiac hypertrophy, the molecular mechanisms employed in this repression are not known. Here we show that continued REST expression prevents increases in the levels of the BNP (Nppb) and ANP (Nppa) genes, encoding brain and atrial natriuretic peptides, in adult rat ventricular myocytes in response to endothelin-1 and that inhibition of REST results in increased expression of these genes in H9c2 cells. Increased expression of Nppb and Nppa correlates with increased histone H4 acetylation and histone H3 lysine 4 methylation of promoter-proximal regions of these genes. Furthermore, using deletions of individual REST repression domains, we show that the combined activities of two domains of REST are required to efficiently repress transcription of the Nppb gene; however, a single repression domain is sufficient to repress the Nppa gene. These data provide some of the first insights into the molecular mechanism that may be important for the changes in gene expression profile seen in cardiac hypertrophy.