Plasma lipidomic profiling reveals metabolic adaptations to pregnancy and signatures of cardiometabolic risk: a preconception and longitudinal cohort study.

BACKGROUND: Adaptations in lipid metabolism are essential to meet the physiological demands of pregnancy and any aberration may result in adverse outcomes for both mother and offspring. However, there is a lack of population-level studies to define the longitudinal changes of maternal circulating lipids from preconception to postpartum in relation to cardiometabolic risk factors. METHODS: LC-MS/MS-based quantification of 689 lipid species was performed on 1595 plasma samples collected at three time points in a preconception and longitudinal cohort, Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO). We mapped maternal plasma lipidomic profiles at preconception (N = 976), 26-28 weeks' pregnancy (N = 337) and 3 months postpartum (N = 282) to study longitudinal lipid changes and their associations with cardiometabolic risk factors including pre-pregnancy body mass index, body weight changes and glycaemic traits. RESULTS: Around 56% of the lipids increased and 24% decreased in concentration in pregnancy before returning to the preconception concentration at postpartum, whereas around 11% of the lipids went through significant changes in pregnancy and their concentrations did not revert to the preconception concentrations. We observed a significant association of body weight changes with lipid changes across different physiological states, and lower circulating concentrations of phospholipids and sphingomyelins in pregnant mothers with higher pre-pregnancy BMI. Fasting plasma glucose and glycated haemoglobin (HbA1c) concentrations were lower whereas the homeostatic model assessment of insulin resistance (HOMA-IR), 2-h post-load glucose and fasting insulin concentrations were higher in pregnancy as compared to both preconception and postpartum. Association studies of lipidomic profiles with these glycaemic traits revealed their respective lipid signatures at three physiological states. Assessment of glycaemic traits in relation to the circulating lipids at preconception with a large sample size (n = 936) provided an integrated view of the effects of hyperglycaemia on plasma lipidomic profiles. We observed a distinct relationship of lipidomic profiles with different measures, with the highest percentage of significant lipids associated with HOMA-IR (58.9%), followed by fasting insulin concentration (56.9%), 2-h post-load glucose concentration (41.8%), HbA1c (36.7%), impaired glucose tolerance status (31.6%) and fasting glucose concentration (30.8%). CONCLUSIONS: We describe the longitudinal landscape of maternal circulating lipids from preconception to postpartum, and a comprehensive view of trends and magnitude of pregnancy-induced changes in lipidomic profiles. We identified lipid signatures linked with cardiometabolic risk traits with potential implications both in pregnancy and postpartum life. Our findings provide insights into the metabolic adaptations and potential biomarkers of modifiable risk factors in childbearing women that may help in better assessment of cardiometabolic health, and early intervention at the preconception period. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03531658.

Evaluation of Normalization Approaches for Quantitative Analysis of Bile Acids in Human Feces.

Quantitative analysis of bile acids in human feces can potentially help to better understand the influence of the gut microbiome and diet on human health. Feces is a highly heterogeneous sample matrix, mainly consisting of water and indigestible solid material (as plant fibers) that show high inter-individual variability. To compare bile acid concentrations among different individuals, a reliable normalization approach is needed. Here, we compared the impact of three normalization approaches, namely sample wet weight, dry weight, and protein concentration, on the absolute concentrations of fecal bile acids. Bile acid concentrations were determined in 70 feces samples from healthy humans. Our data show that bile acid concentrations normalized by the three different approaches are substantially different for each individual sample. Fecal bile acid concentrations normalized by wet weight show the narrowest distribution. Therefore, our analysis will provide the basis for the selection of a suitable normalization approach for the quantitative analysis of bile acids in feces.

Understanding the systemic burden of disease in hidradenitis suppurativa from plasma lipidomic analysis.

BACKGROUND: Hidradenitis suppurativa (HS) is an inflammatory skin condition that is often considered a systemic disease due to its association with metabolic comorbidity. OBJECTIVE: In this study, we aimed to identify differences in plasma lipidomic profiles between HS patients and control subjects. METHODS: HS patients were recruited from a tertiary dermatological centre and demographic and comorbidity matched controls from the general population. A targeted lipidomic approach was performed to characterize over 700 lipid species representing 35 lipid classes/sub-classes. Linear regression models adjusted for confounding factors were used to compare the plasma lipidomic profiles of HS patients to controls. Ordinal regression models were used to study the association of lipids with disease activity and severity scores. RESULTS: 60 HS patients and 73 control subjects were recruited. Differential levels (p < 0.05) of 32 lipid species in HS patients compared to controls were observed, including a decrease in the long chain base d19:1 containing ceramides, and elevation of hydroxyeicosatetraenoic acid (HETE) and dihydroxyeicosatrienoic acid (DHET) oxylipins. These lipids along with several other molecules showed associations with Hurley, HS-PGA and disease activity scores. CONCLUSION: This study found mild changes in plasma lipidomic profiles, consistent with previous studies showing attenuated metabolomic changes in plasma as opposed to lesional skin. However, a number of lipid species were associated with increasing activity and severity of the disease. Further, the significant lipid species within the same class showed consistent trends of increase or decrease in HS as compared to controls.

Tracking genome-editing and associated molecular perturbations by SWATH mass spectrometry.

Advances in gene editing now allow reverse genetics to be applied to a broad range of biological systems. Ultimately, any modification to coding sequences requires confirmation at the protein level, although immunoblotting is often hampered by antibody quality or availability especially in non-model species. Sequential Window Acquisition of All Theoretical Spectra (SWATH), a mass spectrometry (MS) technology with exceptional quantitative reproducibility and accuracy, offers an ideal alternative for protein-based confirmation. Here, using genome edits in mouse, zebrafish and Bicyclus anynana butterflies produced using either homologous recombination or targeted nucleases, we demonstrate absence of the targeted proteins using SWATH, thus confirming successful editing. We show that SWATH is a robust antibody-independent alternative for monitoring gene editing at the protein level and broadly applicable across diverse organisms and targeted genome manipulation techniques. Moreover, SWATH concomitantly defines the global proteome response in the edited organism, which may provide pertinent biological insights.