Integrative metabolomics to identify molecular signatures of responses to vaccines and infections

Approaches to the identification of metabolites have progressed from early biochemical pathway evaluation to modern high-dimensional metabolomics, a powerful tool to identify and characterize biomarkers of health and disease. In addition to its relevance to classic metabolic diseases, metabolomics has been key to the emergence of immunometabolism, an important area of study, as leukocytes generate and are impacted by key metabolites important to innate and adaptive immunity. Herein, we discuss the metabolomic signatures and pathways perturbed by the activation of the human immune system during infection and vaccination. For example, infection induces changes in lipid (e.g., free fatty acids, sphingolipids, and lysophosphatidylcholines) and amino acid pathways (e.g., tryptophan, serine, and threonine), while vaccination can trigger changes in carbohydrate and bile acid pathways. Amino acid, carbohydrate, lipid, and nucleotide metabolism is relevant to immunity and is perturbed by both infections and vaccinations. Metabolomics holds substantial promise to provide fresh insight into the molecular mechanisms underlying the host immune response. Its integration with other systems biology platforms will enhance studies of human health and disease

Complement and coagulation cascades activation is the main pathophysiological pathway in early-onset severe preeclampsia revealed by maternal proteomics

Preeclampsia is a pregnancy-specific multisystem disorder and a leading cause of maternal and perinatal morbidity and mortality. The exact pathogenesis of this multifactorial disease remains poorly defined. We applied proteomics analysis on maternal blood samples collected from 14 singleton pregnancies with early-onset severe preeclampsia and 6 uncomplicated pregnancies to investigate the pathophysiological pathways involved in this specific subgroup of preeclampsia. Maternal blood was drawn at diagnosis for cases and at matched gestational age for controls. LC-MS/MS proteomics analysis was conducted, and data were analyzed by multivariate and univariate statistical approaches with the identification of differential pathways by exploring the global human protein-protein interaction network. The unsupervised multivariate analysis (the principal component analysis) showed a clear difference between preeclamptic and uncomplicated pregnancies. The supervised multivariate analysis using orthogonal partial least square discriminant analysis resulted in a model with goodness of fit (R2X = 0.99, p < 0.001) and a strong predictive ability (Q2Y = 0.8, p < 0.001). By univariate analysis, we found 17 proteins statistically different after 5% FDR correction (q-value < 0.05). Pathway enrichment analysis revealed 5 significantly enriched pathways whereby the activation of the complement and coagulation cascades was on top (p = 3.17e-07). To validate these results, we assessed the deposits of C5b-9 complement complex and on endothelial cells that were exposed to activated plasma from an independent set of 4 cases of early-onset severe preeclampsia and 4 uncomplicated pregnancies. C5b-9 and Von Willbrand factor deposits were significantly higher in early-onset severe preeclampsia. Future studies are warranted to investigate potential therapeutic targets for early-onset severe preeclampsia within the complement and coagulation pathway

Strengthening Primary Health Care Through Community Health Workers: Investment Case And Financing Recommendations

A report released this week at the Third International Conference on Financing for Development found that there is a strong case for investing in Community Health Worker (CHW) programs as part of integrated health systems. The report was released by leaders from the Federal Democratic Republic of Ethiopia, the Republic of Liberia, the U.N. Secretary General's Special Envoy for Financing the Health MDGs and for Malaria, Partners in Health, the Clinton Foundation, the African Leaders Malaria Alliance, and the MDG Health Alliance. The authors encourage domestic governments, international financers, bilateral and multilateral donors, and the broader global health community to finance and support the scale up of CHW programs as part of community-based primary health care through a set of specific recommendations. The authors participated in the crafting of the report and its recommendations as part of a distinguished panel chaired by Ray Chambers, the UN Secretary General's Special Envoy for Financing the Health MDGs and for Malaria, and Prime Minister Hailemariam Dessalegn, President of the Federal Democratic Republic of Ethiopia

Genetic and genomic mechanisms of neonatal hyperoxic lung injury in the inbred mouse

Oxidative stress contributes to the pathogenesis of many respiratory disorders, including bronchopulmonary dysplasia (BPD), or chronic lung disease in infants. Treatment of BPD often involves respiratory support with high oxygen levels, and oxidant injury is an adverse side effect associated with vascular damage and impaired lung development and function in a subset of infants. Differential susceptibility to BPD is poorly understood and previous studies have demonstrated genetic susceptibility to hyperoxic lung injury in strains of adult inbred mice. Furthermore, genetic polymorphisms in a few candidate genes have been associated with BPD in clinical cohorts; however, specific genetic factors predisposing neonates to oxidant lung injury are poorly understood. The objective of this dissertation was to utilize integrated genetic and genomic approaches to identify predictors of susceptibility to neonatal hyperoxic lung injury. Neonates from 36 strains of inbred mice were screened for lungDoctor of Philosoph

A Toll-Like Receptor 2 Pathway Regulates the Ppargc1a/b Metabolic Co-Activators in Mice with Staphylococcal aureus Sepsis

Activation of the host antibacterial defenses by the toll-like receptors (TLR) also selectively activates energy-sensing and metabolic pathways, but the mechanisms are poorly understood. This includes the metabolic and mitochondrial biogenesis master co-activators, Ppargc1a (PGC-1α) and Ppargc1b (PGC-1β) in Staphylococcus aureus (S. aureus) sepsis. The expression of these genes in the liver is markedly attenuated inTLR2−/− mice and markedly accentuated in TLR4−/− mice compared with wild type (WT) mice. We sought to explain this difference by using specific TLR-pathway knockout mice to test the hypothesis that these co-activator genes are directly regulated through TLR2 signaling. By comparing their responses to S. aureus with WT mice, we found that MyD88-deficient and MAL-deficient mice expressed hepatic Ppargc1a and Ppargc1b normally, but that neither gene was activated in TRAM-deficient mice. Ppargc1a/b activation did not require NF-kβ, but did require an interferon response factor (IRF), because neither gene was activated in IRF-3/7 double-knockout mice in sepsis, but both were activated normally in Unc93b1-deficient (3d) mice. Nuclear IRF-7 levels in TLR2−/− and TLR4−/− mice decreased and increased respectively post-inoculation and IRF-7 DNA-binding at the Ppargc1a promoter was demonstrated by chromatin immunoprecipitation. Also, a TLR2-TLR4-TRAM native hepatic protein complex was detected by immunoprecipitation within 6 h of S. aureus inoculation that could support MyD88-independent signaling to Ppargc1a/b. Overall, these findings disclose a novel MyD88-independent pathway in S. aureus sepsis that links TLR2 and TLR4 signaling in innate immunity to Ppargc1a/b gene regulation in a critical metabolic organ, the liver, by means of TRAM, TRIF, and IRF-7

Oxylipin metabolism is controlled by mitochondrial β-oxidation during bacterial inflammation

Oxylipins are potent biological mediators requiring strict control, but how they are removed en masse during infection and inflammation is unknown. Here we show that lipopolysaccharide (LPS) dynamically enhances oxylipin removal via mitochondrial β-oxidation. Specifically, genetic or pharmacological targeting of carnitine palmitoyl transferase 1 (CPT1), a mitochondrial importer of fatty acids, reveal that many oxylipins are removed by this protein during inflammation in vitro and in vivo. Using stable isotope-tracing lipidomics, we find secretion-reuptake recycling for 12-HETE and its intermediate metabolites. Meanwhile, oxylipin β-oxidation is uncoupled from oxidative phosphorylation, thus not contributing to energy generation. Testing for genetic control checkpoints, transcriptional interrogation of human neonatal sepsis finds upregulation of many genes involved in mitochondrial removal of long-chain fatty acyls, such as ACSL1,3,4, ACADVL, CPT1B, CPT2 and HADHB. Also, ACSL1/Acsl1 upregulation is consistently observed following the treatment of human/murine macrophages with LPS and IFN-γ. Last, dampening oxylipin levels by β-oxidation is suggested to impact on their regulation of leukocyte functions. In summary, we propose mitochondrial β-oxidation as a regulatory metabolic checkpoint for oxylipins during inflammation

Developing a patient-centred care pathway for paediatric critical care in the Western Cape

Includes bibliographical referencesBackground: Emergency care of critically ill or injured children requires prompt identification, high quality treatment and rapid referral. This study examines the critical care pathways in a health system to identify preventable care failures by evaluating the entire pathway to care, the quality of care at each step along the referral pathway, and the impact on patient outcomes. Methods: A year-long cohort study of critically ill and injured children was performed in Cape Town, South Africa, from first presentation until paediatric intensive care unit admission or emergency centre death, using a modified confidential enquiry process of expert panel review and caregiver interview. Outcomes were expert panel assessment of quality of care, avoidability of death or PICU admission and severity at PICU admission, identification of modifiable factors, adherence to consensus standards of care, as well as time delays and objective measures of severity and outcome. Results: The study enrolled 282 children: 85% medical and 15% trauma cases (252 emergency admissions, and 30 children who died at referring health facilities). Global quality of care was graded poor in 57(20%) of all cases and 141(50%) had at least one major impact modifiable factor. Key modifiable factors related to access and identification of the critically ill, assessment of severity, inadequate resuscitation, delays in decision making and referral, and access to paediatric intensive care. Standards compliance increased with increasing level of healthcare facility, as did caregiver satisfaction. Children presented primarily to primary health care (54%), largely after hours (65%), and were transferred with median time from first presentation to PICU admission of 12.3 hours. There was potentially avoidable severity of illness in 74% of children, indicating room for improvement. Conclusions and Relevance: The study presents a novel methodology, examining the quality of paediatric critical care across a health system in a middle income country. The findings highlight the complexity of the care pathway and focus attention on specific issues, many amenable to suggested interventions that could reduce mortality and morbidity, and optimize scarce critical care resources; as well as demonstrating the importance of continuity and quality of care throughout the referral pathway