The diagnostic value of apolipoprotein E in pediatric patients with invasive bacterial infections

Investigating Blood Biomarkers That Can Facilitate the Diagnosis of Meningitis-A Systematic Literature Review

Meningitis is an inflammation of the meninges that can sometimes be a life-threatening disease. Therefore, fast and proper diagnosis with the implementation of adequate treatment is crucial in its management. Treatment depends on etiology, which can be viral, bacterial, fungal, and parasitic. Diagnosis is based on thorough clinical examination with a performance of lumbar puncture in the case of meningitis suspicion. This procedure, however, remains invasive with several contraindications and a need for a patient's consent, which is not always given due to the patient's fear of it, for instance. Thus, this systematic review aimed to summarize the available literature on the topic of blood biomarkers in meningitis differentiation. A selection process was performed by two authors independently in accordance with the Preferred Research Items for Systematic Reviews and Meta-analyses. Two databases were screened. It led to the identification of 863 articles, of which 43 were eventually included in the systematic review. The analysis resulted in identifying blood biomarkers in both adult and pediatric meningitis. Most studies focused on inflammatory markers, such as C-reactive protein and procalcitonin, from which procalcitonin showed better utility. Among other analyzed molecules were, for instance, interleukins, apolipoproteins, and microRNAs. Moreover, many researchers suggested that combining biomarkers or implementing novel technologies may lead to the best accuracy. However, many suggested methods lack validation, which stands in the way of making them widely used.

Genome-Wide Meta-Analysis Identifies Multiple Novel Rare Variants to Predict Common Human Infectious Diseases Risk

Infectious diseases still threaten global human health, and host genetic factors have been indicated as determining risk factors for observed variations in disease susceptibility, severity, and outcome. We performed a genome-wide meta-analysis on 4624 subjects from the 10,001 Dalmatians cohort, with 14 infection-related traits. Despite a rather small number of cases in some instances, we detected 29 infection-related genetic associations, mostly belonging to rare variants. Notably, the list included the genes CD28, INPP5D, ITPKB, MACROD2, and RSF1, all of which have known roles in the immune response. Expanding our knowledge on rare variants could contribute to the development of genetic panels that could assist in predicting an individual's life-long susceptibility to major infectious diseases. In addition, longitudinal biobanks are an interesting source of information for identifying the host genetic variants involved in infectious disease susceptibility and severity. Since infectious diseases continue to act as a selective pressure on our genomes, there is a constant need for a large consortium of biobanks with access to genetic and environmental data to further elucidate the complex mechanisms behind host-pathogen interactions and infectious disease susceptibility.

Proteins Involved in Synaptic Plasticity Are Downregulated in the Cerebrospinal Fluid of Infants With Clinical Sepsis Complicated by Neuroinflammation

Newborn infants are prone to sepsis and related inflammation of different organs. Neuroinflammation has been associated with long-term adverse neuronal (neuropsychiatric/neurodegenerative) outcomes, including attention deficit hyperactivity disorder (ADHD) or even Alzheimer's disease. Despite a vast number of findings on sepsis-induced inflammatory responses in the central nervous system (CNS), how neuroinflammation affects brain development remains largely elusive. In this study, neonates with clinical sepsis and screened for meningitis were included and classified by the neuroinflammation status based on cerebrospinal fluid (CSF) parameters (INF vs. NOINF). CSF samples collected from clinical screening were subjected to proteomics analysis. Proteins with differential abundance were subjected to enrichment analysis to reveal affected biological pathways. INF and NOINF infants had similar demographic data and hematological and biochemical parameters in blood and CSF. The CSF proteomes were essentially different between the two groups. All 65 proteins with differential abundance showed lower abundance in the INF group and functionally covered pivotal developmental processes, including axonal and synaptic function and extracellular homeostasis. CSF proteins, PTPRZ1 and IGFBP4, were correlated with C-reactive protein (CRP) and ratios of immature/total neutrophils in blood. In general, a substantial change in the CSF protein profile was found under neuroinflammation, and these changes are related to systemic conditions. The results suggest that changes in CSF proteins may be involved in sepsis-affected neurodevelopment, such as disturbances in circuit formation, which has the potential to predispose neonates to long-term adverse outcomes.

Candidate Biomarkers for the Detection of Serious Infections in Children: A Prospective Clinical Study

Serious bacterial infections (SBI) in children are associated with considerable morbidity and mortality, and their early identification remains challenging. The role of laboratory tests in this setting is still debated, and new biomarkers are needed. This prospective, observational, single-center study aims to evaluate the diagnostic role of blood biomarkers in detecting SBI in children presenting with signs of systemic inflammatory response syndrome (SIRS). A panel of biomarkers was performed, including C-reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), absolute neutrophil count (ANC), interleukin (IL)-6, IL-8, IL-10, human terminal complement complex (C5b-9), Plasmalemma-Vesicle-associated protein 1 (PV-1), Intercellular Adhesion Molecule-1 (ICAM-1), and Phospholipase A2 (PLA2). Among 103 patients (median age 2.9 years, 60% males), 39 had a diagnosis of SBI (38%). Significant predictors of SBI were CRP (p = 0.001) and ICAM-1 (p = 0.043). WBC (p = 0.035), ANC (p = 0.012) and ANC/WBC ratio (p = 0.015) were also significantly associated with SBI in children without pre-existing neutropenia. ROC curves, however, revealed suboptimal performance for all variables. Nevertheless, a model that combined CRP and ANC/WBC ratio had more in-depth diagnostic accuracy than either of the two variables. Overall, this study confirms the limited usefulness of blood biomarkers for the early diagnosis of SBI. WBC, ANC, ANC/WBC ratio, CRP, and ICAM-1 showed the best, albeit moderate, diagnostic accuracy.

Comparison of urine proteome among rat models by intraperitoneal injection with single bacteria and co-injection with two bacteria

PURPOSE

To explore and compare urine proteome changes among rat models by intraperitoneal injection with single bacteria and co-injection with two bacteria.

METHOD

Escherichia coli and Staphylococcus aureus are two common human pathogens. Three rat models were established: (i) the intraperitoneal co-injection of E. coli and S. aureus model (ES model), (ii) intraperitoneal injection of E. coli model (E model), and (iii) intraperitoneal injection of S. aureus model (S model). Urinary proteomes on days 0, 1 and 2 of the three models were analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).

RESULTS

A total of 111, 34 and 94 differential proteins were identified in the ES model, E model and S model, respectively. Among them, some differential proteins were reported to be associated with bacterial infection. Approximately 47% differential proteins in the E model overlapped with ES model, and 37% differential proteins in the S model overlapped with ES model. Compared with the E model and S model, a total of 71 unique differential proteins were identified in the ES model.

CONCLUSION

Our results indicated that (1) the urine proteome could distinguish different bacterial intraperitoneal injections models and (2) the effects of co-injection with two bacteria on the urine proteome were not simple superposition of single injection.

Cerebrospinal fluid proteome maps detect pathogen-specific host response patterns in meningitis

Meningitis is a potentially life-threatening infection characterized by the inflammation of the leptomeningeal membranes. Many different viral and bacterial pathogens can cause meningitis, with differences in mortality rates, risk of developing neurological sequelae, and treatment options. Here, we constructed a compendium of digital cerebrospinal fluid (CSF) proteome maps to define pathogen-specific host response patterns in meningitis. The results revealed a drastic and pathogen-type specific influx of tissue-, cell-, and plasma proteins in the CSF, where, in particular, a large increase of neutrophil-derived proteins in the CSF correlated with acute bacterial meningitis. Additionally, both acute bacterial and viral meningitis result in marked reduction of brain-enriched proteins. Generation of a multiprotein LASSO regression model resulted in an 18-protein panel of cell- and tissue-associated proteins capable of classifying acute bacterial meningitis and viral meningitis. The same protein panel also enabled classification of tick-borne encephalitis, a subgroup of viral meningitis, with high sensitivity and specificity. The work provides insights into pathogen-specific host response patterns in CSF from different disease etiologies to support future classification of pathogen type based on host response patterns in meningitis.

Biomarkers in pediatric sepsis: a review of recent literature

Sepsis remains the leading cause of death in infants and children worldwide. Prompt diagnosis and monitoring of infection is pivotal to guide therapy and optimize outcomes. No single biomarker has so far been identified to accurately diagnose sepsis, monitor response and predict severity. We aimed to assess existing evidence of available sepsis biomarkers, and their utility in pediatric population. C-reactive protein and procalcitonin remain the most extensively evaluated and used biomarkers. However, biomarkers related to endothelial damage, vasodilation, oxidative stress, cytokines/chemokines and cell bioproducts have also been identified, often with regard to the site of infection and etiologic pathogen; still, with controversial utility. A multi-biomarker model driven by genomic tools could establish a personalized approach in future disease management.

Postseptic Cognitive Impairment and Expression of APOE in Peripheral Blood: The Cognition After SepsiS (CASS) Observational Pilot Study

BACKGROUND

Cognitive impairment after sepsis is an important clinical problem. Determinants of postseptic cognitive impairment are not well understood. We thus undertook a systems biology approach to exploring a possible role for apolipoprotein E (APOE) in postseptic cognitive impairment.

DESIGN

Prospective, observational cohort.

SETTING

Intermountain Medical Center, a tertiary referral center in Utah.

PATIENTS/PARTICIPANTS

Patients with sepsis admitted to study intensive care units.

INTERVENTIONS

None.

METHODS

We obtained peripheral blood for deep sequencing of RNA and followed up survivors at 6 months with a battery of cognitive instruments. We defined cognitive impairment based on the 6-month Hayling test of executive function. In our primary analysis, we employed weighted network analysis. Secondarily, we compared variation in gene expression between patients with normal versus impaired cognition.

MEASUREMENTS AND MAIN RESULTS

We enrolled 40 patients, of whom 34 were follow-up eligible and 31 (91%) completed follow-up; 1 patient's RNA sample was degraded-the final analytic cohort was 30 patients. Mean Hayling test score was 5.8 (standard deviation 1.1), which represented 20% with impaired executive function. The network module containing APOE was dominated by low-expression genes, with no association on primary analysis (P = .8). Secondary analyses suggested several potential lines of future investigation, including oxidative stress.

CONCLUSIONS

In this prospective pilot cohort, executive dysfunction affected 1 in 5 survivors of sepsis. The APOE gene was sparsely transcribed in peripheral leukocytes and not associated with cognitive impairment. Future lines of research are suggested.

Collection and Analyses of Cerebrospinal Fluid for Pediatric Translational Research

Cerebrospinal fluid sample collection and analysis is imperative to better elucidate central nervous system injury and disease in children. Sample collection methods are varied and carry with them certain ethical and biologic considerations, complications, and contraindications. Establishing best practices for sample collection, processing, storage, and transport will ensure optimal sample quality. Cerebrospinal fluid samples can be affected by a number of factors including subject age, sampling method, sampling location, volume extracted, fraction, blood contamination, storage methods, and freeze-thaw cycles. Indicators of sample quality can be assessed by matrix-associated laser desorption/ionization time-of-flight mass spectrometry and include cystatin C fragments, oxidized proteins, prostaglandin D synthase, and evidence of blood contamination. Precise documentation of sample collection processes and the establishment of meticulous handling procedures are essential for the creation of clinically relevant biospecimen repositories. In this review we discuss the ethical considerations and best practices for cerebrospinal fluid collection, as well as the influence of preanalytical factors on cerebrospinal fluid analyses. Cerebrospinal fluid biomarkers in highly researched pediatric diseases or disorders are discussed.

Emerging Roles of Apolipoprotein E and Apolipoprotein A-I in the Pathogenesis and Treatment of Lung Disease

Emerging roles are being recognized increasingly for apolipoproteins in the pathogenesis and treatment of lung diseases on the basis of their ability to suppress inflammation, oxidative stress, and tissue remodeling, and to promote adaptive immunity and host defense. Apolipoproteins, such as apolipoprotein E (apoE) and apolipoprotein A-I (apoA-I), are important components of lipoprotein particles that facilitate the transport of cholesterol, triglycerides, and phospholipids between plasma and cells. ApoE-containing lipoprotein particles are internalized into cells by low-density lipoprotein receptors (LDLRs), whereas apoA-I can interact with the ATP-binding cassette subfamily A member 1 (ABCA1) transporter to efflux cholesterol and phospholipids out of cells. ApoE and apoA-I also mediate receptor-independent effects, such as binding to and neutralizing LPS. Both apoE and apoA-I are expressed by lung cells, which allows apoE/LDLR- and apoA-I/ABCA1-dependent pathways to modulate normal lung health and the pathogenesis of respiratory diseases, including asthma, acute lung injury, cancer, emphysema, pulmonary fibrosis, and pulmonary hypertension. Data from human studies and research using experimental murine model systems have shown that both apoE and apoA-I pathways play primarily protective roles in lung biology and respiratory disease. Furthermore, apolipoprotein mimetic peptides, corresponding to the LDLR-binding domain of apoE or the class A amphipathic α-helical structure of apoA-I, have antiinflammatory and antioxidant effects that attenuate the severity of lung disease in murine models. Thus, the development of inhaled apolipoprotein mimetic peptides as a novel treatment paradigm could represent a significant advance for patients with respiratory disease who do not respond to current therapies.

A Biomarker-Based Approach to Infectious Disease in the Pediatric Emergency Department

In modern pediatric emergency medicine, biomarker-based assays that enable quick bedside diagnostics and subsequent disease management can be valuable. There is a growing need for novel, disease-specific biomarkers that can improve the outcome of pediatric infectious diseases commonly encountered in the emergency department (ED). Viral respiratory infections, central nervous system infections, sepsis, and septic shock are acute disease states frequently encountered in the ED. In this review, we describe a host of novel biomarkers, including a diverse set of cytokines, chemokines, and nitric oxide–based metabolites. Based on disease pathophysiology, a rationale is provided for a molecular- or biomarker-based approach in the ED. Throughout this review, emphasis is placed on diagnostic rapidity because this relates directly to timeliness and quality of care in a busy ED. Once the biomarkers become more clinically available, in a rapid ED setting as bedside point-of-care assays, quality of care will be enhanced, not only by means of diagnostics but also in prognosticating severity of illness.