Interleukin-18 binding protein in infants and children hospitalized with pneumonia in low-resource settings.

Pneumonia is the leading infectious cause of death in children, with especially high mortality in low- and middle-income countries. Interleukin-18 binding protein (IL-18BP) is a natural antagonist of the pro-inflammatory cytokine interleukin-18 and is elevated in numerous autoimmune conditions and infectious diseases. We conducted a prospective cohort study to determine the association between admission IL-18BP levels and clinical severity among children admitted to two hospitals in Uganda for hypoxemic pneumonia. A total of 42 children (median age of 1.2 years) were included. IL-18BP levels were higher in patients with respiratory distress, including chest indrawing (median 15 ng/mL (IQR 9.8-18) versus 4.5 ng/mL (IQR 3.8-11) without chest indrawing, P = 0.0064) and nasal flaring (median 15 ng/mL (IQR 9.7-19) versus 11 ng/mL (IQR 5.4-14) without nasal flaring, P = 0.034). IL-18BP levels were positively correlated with the composite clinical severity score, Pediatric Early Death Index for Africa (PEDIA-e, ρ = 0.46, P = 0.0020). Patients with IL-18BP > 14 ng/mL also had slower recovery times, including time to sit (median 0.69 days (IQR 0.25-1) versus 0.15 days (IQR 0.076-0.36) with IL-18BP < 14 ng/mL, P = 0.036) and time to fever resolution (median 0.63 days (IQR 0.16-2) versus 0.13 days (IQR 0-0.42), P = 0.016). In summary, higher IL-18BP levels were associated with increased disease severity and prolonged recovery times in Ugandan children with pneumonia.

Soluble T cell immunoglobulin and mucin-domain containing protein 3 in children hospitalized with pneumonia in resource-limited settings.

In a prospective cohort study of 77 children with severe pneumonia from two hospitals in Uganda, we assessed soluble T cell immunoglobulin and mucin-domain containing protein 3 (sTIM-3) levels at hospital admission and their association with pneumonia severity and subsequent mortality. sTIM-3 levels were positively correlated with the Respiratory Index of Severity in Children (RISC) (ρ = 0.35, p = 0.0017), sTIM-3 levels were higher in children who required transfer to a tertiary hospital (p = 0.014) and in fatal cases (p = 0.011). In summary, sTIM-3 is associated with disease severity and predictive of mortality in childhood pneumonia in resource-limited settings.

Dysregulation of angiopoietin-Tie-2 axis in ugandan children hospitalized with pneumonia.

OBJECTIVE: Pneumonia is the leading cause of death in children under 5, with the highest burden in resource-limited countries. Endothelial activation occurs in pneumonia and can be assessed using quantitative levels of biomarkers angiopoietin (Ang)-1 and Ang-2. We examined admission levels of Ang-1 and Ang-2 in pediatric pneumonia and their association with disease severity and outcome. METHODS: Prospective cohort study of children with hypoxemic pneumonia admitted to two hospitals in Uganda. Clinical, radiographic, and microbiologic characteristics were measured at admission. Disease severity was assessed using the Respiratory Index of Severity in Children (RISC). Plasma levels of Ang-1 and Ang-2 were quantified by enzyme-linked immunosorbent assay. Vital signs, oxygen supplementation, and mortality were assessed prospectively. RESULTS: We included 65 patients (43% female) with median age 19 months (IQR 8-24). Admission Ang-2/Ang-1 ratio directly correlated with RISC (ρ = 0.32, p = 0.008) and lactate level (ρ = 0.48, p < 0.001). Ang-2/Ang-1 ratio was higher in pneumococcal pneumonia than viral RTI (0.19 [IQR: 0.076-0.54] vs. 0.078 [IQR: 0.027-0.11]; p = 0.03). Elevated Ang-2/Ang-1 ratio (>0.084) was associated with prolonged tachypnea (HR 0.50 (95%CI 0.29-0.87), p = 0.02), fever (HR 0.56 (95%CI 0.33 to 0.96), p = 0.02), longer duration of oxygen therapy (HR 0.59 (95%CI 0.35-0.99), p = 0.04), and hospital stay (HR 0.43 (95%CI 0.25-0.74), p = 0.001). The Ang-2/Ang-1 ratio at admission was higher in fatal cases relative to survivors (0.36 [IQR: 0.17-0.58] vs. 0.077 [IQR: 0.025-0.19]; p = 0.05) CONCLUSION: Endothelial activation in hypoxemic pediatric pneumonia, reflected by high plasma Ang-2/Ang-1 ratio, is associated with disease severity, prolonged recovery time, and mortality.

Silencing by H-NS potentiated the evolution of Salmonella.

The bacterial H-NS protein silences expression from sequences with higher AT-content than the host genome and is believed to buffer the fitness consequences associated with foreign gene acquisition. Loss of H-NS results in severe growth defects in Salmonella, but the underlying reasons were unclear. An experimental evolution approach was employed to determine which secondary mutations could compensate for the loss of H-NS in Salmonella. Six independently derived S. Typhimurium hns mutant strains were serially passaged for 300 generations prior to whole genome sequencing. Growth rates of all lineages dramatically improved during the course of the experiment. Each of the hns mutant lineages acquired missense mutations in the gene encoding the H-NS paralog StpA encoding a poorly understood H-NS paralog, while 5 of the mutant lineages acquired deletions in the genes encoding the Salmonella Pathogenicity Island-1 (SPI-1) Type 3 secretion system critical to invoke inflammation. We further demonstrate that SPI-1 misregulation is a primary contributor to the decreased fitness in Salmonella hns mutants. Three of the lineages acquired additional loss of function mutations in the PhoPQ virulence regulatory system. Similarly passaged wild type Salmonella lineages did not acquire these mutations. The stpA missense mutations arose in the oligomerization domain and generated proteins that could compensate for the loss of H-NS to varying degrees. StpA variants most able to functionally substitute for H-NS displayed altered DNA binding and oligomerization properties that resembled those of H-NS. These findings indicate that H-NS was central to the evolution of the Salmonellae by buffering the negative fitness consequences caused by the secretion system that is the defining characteristic of the species.

Chronic mild stress and antidepressant treatment alter 5-HT1A receptor expression by modifying DNA methylation of a conserved Sp4 site.

The serotonin 1A receptor (5-HT1A), a critical regulator of the brain serotonergic tone, is implicated in major depressive disorder (MDD) where it is often found to be dys-regulated. However, the extent to which stress and antidepressant treatment impact 5-HT1A expression in adults remains unclear. To address this issue, we subjected adult male BALB/c mice to unpredictable chronic mild stress (UCMS) to induce a depression-like phenotype that was reversed by chronic treatment with the antidepressant imipramine. In prefrontal cortex (PFC) and midbrain tissue, UCMS increased 5-HT1A RNA and protein levels, changes that are expected to decrease the brain serotonergic activity. The stress-induced increase in 5-HT1A expression was paralleled by a specific increase in DNA methylation of the conserved -681 CpG promoter site, located within a Sp1-like element. We show that the -681 CpG site is recognized and repressed by Sp4, the predominant neuronal Sp1-like factor and that Sp4-induced repression is attenuated by DNA methylation, despite a stress-induced increase in PFC Sp4 levels. These results indicate that adult life stress induces DNA methylation of a conserved promoter site, antagonizing Sp4 repression to increase 5-HT1A expression. Chronic imipramine treatment fully reversed the UCMS-induced increase in methylation of the -681 CpG site in the PFC but not midbrain of stressed animals and also increased 5-HT1A expression in the PFC of control animals. Incomplete reversal by imipramine of stress-induced changes in 5-HT1A methylation and expression indicates a persistence of stress vulnerability, and that sustained reversal of behavioral impairments may require additional pathways.

Circulating markers of neutrophil activation and lung injury in pediatric pneumonia in low-resource settings.

Diagnostic biomarkers for childhood pneumonia could guide management and improve antibiotic stewardship in low-resource settings where chest x-ray (CXR) is not always available. In this cross-sectional study, we measured chitinase 3-like protein 1 (CHI3L1), surfactant protein D (SP-D), lipocalin-2 (LCN2), and tissue inhibitor of metalloproteinases-1 (TIMP-1) in Ugandan children under the age of five hospitalized with acute lower respiratory tract infection. We determined the association between biomarker levels and primary end-point pneumonia, indicated by CXR consolidation. We included 89 children (median age 11 months, 39% female). Primary endpoint pneumonia was present in 22 (25%). Clinical signs were similar in children with and without CXR consolidation. Broad-spectrum antibiotics (ceftriaxone) were administered in 83 (93%). Levels of CHI3L1, SP-D, LCN2 and TIMP-1 were higher in patients with primary end-point pneumonia compared to patients with normal CXR or other infiltrates. All markers were moderately accurate predictors of primary end-point pneumonia, with area under receiver operator characteristic curves of 0.66-0.70 (p<0.05 for all markers). The probability of CXR consolidation increased monotonically with the number of markers above cut-off. Among 28 patients (31%) in whom all four markers were below the cut-off, the likelihood ratio of CXR consolidation was 0.11 (95%CI 0.015 to 0.73). CHI3L1, SP-D, LCN2 and TIMP-1 were associated with CXR consolidation in children with clinical pneumonia in a low-resource setting. Combinations of quantitative biomarkers may be useful to safely withhold antibiotics in children with a low probability of bacterial infection.

Biomarkers of Systemic Inflammation in Ugandan Infants and Children Hospitalized With Respiratory Syncytial Virus Infection.

BACKGROUND: Optimizing outcomes in respiratory syncytial virus (RSV) pneumonia requires accurate diagnosis and determination of severity that, in resource-limited settings, is often based on clinical assessment alone. We describe host inflammatory biomarkers and clinical outcomes among children hospitalized with RSV lower respiratory tract infection (LRTI) in Uganda and controls with rhinovirus and pneumococcal pneumonia. METHODS: 58 children hospitalized with LRTI were included. We compared 37 patients with RSV, 10 control patients with rhinovirus and 11 control patients with suspected pneumococcal pneumonia. RESULTS: Patients in the RSV group had significantly lower levels of C-reactive protein (CRP) and chitinase-3-like protein 1 (CHI3L1) than the pneumococcal pneumonia group (P < 0.05 for both). Among children with RSV, higher admission levels of CRP predicted prolonged time to resolution of tachypnea, tachycardia and fever. Higher levels of CHI3L1 were associated with higher composite clinical severity scores and predicted prolonged time to resolution of tachypnea and tachycardia, time to wean oxygen and time to sit. Higher levels of lipocalin-2 (LCN2) predicted prolonged time to resolution of tachypnea, tachycardia and time to feed. Higher admission levels of all 3 biomarkers were predictive of a higher total volume of oxygen administered during hospitalization (P < 0.05 for all comparisons). Of note, CHI3L1 and LCN2 appeared to predict clinical outcomes more accurately than CRP, the inflammatory biomarker most widely used in clinical practice. CONCLUSIONS: Our findings suggest that CHI3L1 and LCN2 may be clinically informative biomarkers in childhood RSV LRTI in low-resource settings.

Brief Report: Higher Levels of Angiopoietin-1 Are Associated With Early and Sustained Viral Suppression in Children Living With Vertically Acquired HIV.

BACKGROUND: Systemic inflammation, platelet dysfunction, and endothelial activation persist in people living with HIV despite sustained virologic suppression (SVS) with combined antiretroviral therapy (cART) and may lead to complications such as atherosclerosis and cardiovascular disease. Angiopoietin-1 (Ang-1) is a key regulator of angiogenesis and endothelial activation and has been studied as an objective biomarker in disease states such as atherosclerosis, sepsis, and severe malaria. SETTING: Eight pediatric HIV care centers across Canada. METHODS: Cross-sectional study of 61 children living with vertically acquired HIV on cART with undetectable RNA viral load. Plasma levels of Ang-1 were measured by ELISA and analyzed in relation to clinical characteristics abstracted from medical records. RESULTS: Ang-1 levels were directly correlated with clinical indices of virologic control: cumulative proportion of life on effective cART (ρ = +0.35, P = 0.0078) and cumulative proportion of life with SVS (ρ = +0.36, P = 0.0049). Furthermore, higher Ang-1 levels were associated with younger age at SVS (ρ = -0.56, P < 0.0001). These associations remained statistically significant in multivariable linear regression models adjusting for potential confounders (P < 0.05 for all associations). CONCLUSIONS: Early effective cART and SVS were associated with higher Ang-1 levels in children living with vertically acquired HIV-1.