Immunoglobulins IgG1, IgM and IgA: a synergistic team influencing survival in sepsis.

OBJECTIVE: The impact of endogenous immunoglobulin isotypes on the prognosis of patients with severe sepsis has not been sufficiently explored. The aim of this study was to evaluate the association between immunoglobulin levels in plasma and survival in patients with this condition. DESIGN AND PATIENTS: A prospective multicentre cohort study was conducted. A total of 172 adult patients admitted to the intensive care unit (ICU) with severe sepsis or septic shock were recruited. Patients were classified based on deciles of immunoglobulin concentrations at diagnosis of sepsis. Categorical variables were created and tested for their association with survival during hospitalization in the ICU. RESULTS: Overall, 42 patients died in the ICU during the study. Kaplan-Meier analysis showed that immunoglobulin concentrations below 300 mg dL(-1) for IgG1, 35 mg dL(-1) for IgM and 150 mg dL(-1) for IgA were associated with shorter survival times. Multivariate regression analysis showed that IgG1 < 300 mg dL(-1) was a risk factor for mortality [odds ratio (OR) 2.50, 95% confidence interval (CI) 1.04-6.03; P = 0.042]. The combined presence of IgG1, IgM and IgA levels below the described thresholds had a synergistic impact on mortality risk (OR 5.27, 95% CI 1.41-19.69; P = 0.013). A similar effect was observed for combined low levels of IgG1 and IgA (OR 4.10, 95% CI 1.28-13.12; P = 0.018) and also of IgG1 and IgM (OR 3.10. 95% CI 1.13-8.49; P = 0.028). CONCLUSIONS: The combined presence of low levels of the endogenous immunoglobulins IgG1, IgM and IgA in plasma is associated with reduced survival in patients with severe sepsis or septic shock. Assessment of the concentrations of these immunoglobulins could improve the results of treatment with exogenous immunoglobulins in patients with sepsis.

Intubated patients developing tracheobronchitis or pneumonia have distinctive complement system gene expression signatures in the pre-infection period: a pilot study.

INTRODUCTION: It remains unknown why some intubated patients remain infection-free while others develop tracheobronchitis (VAT) or pneumonia (VAP). OBJECTIVE: To identify and compare VAP/VAT gene expression "signatures" using genome-wide oligonucleotide microarrays. MATERIAL AND METHODS: A prospective translational study of gene expression profiles of VAP and VAT groups was carried out, establishing comparisons in both pre-infection and infection phases. Pathway and functional analyses were performed with Ingenuity Pathway Analysis (IPA). Data analysis and hierarchical clustering of the genes involved in the signalling pathways expressed differentially in the two groups were performed with GeneSpring GX 11.0. RESULTS: Eight patients developing respiratory infections (3 VAP and 5 VAT) after 4 days of mechanical ventilation were assessed. Comparison of gene expression profiles in the pre-infection period revealed 5595 genes expressed differentially between VAP and VAT (p<0.01, fold change >2). Comparative IPA analysis identified a significant depression of the complement system signalling pathway in the VAP group, affecting the classical pathway along with the final common pathway (p<0.05). In addition, the cAMP and calcium signalling pathways were also significantly depressed in the VAP group during the pre-infection phase also. CONCLUSION: Intubated patients complicated with pneumonia developed immune impairment in the pre-infection period, manifesting as a relatively lower expression of genes involved in the complement system that differed from patients developing tracheobronchitis. These findings suggest that a significant proportion of VAP episodes cannot be prevented, but might be treatable through pre-emptive therapy.

Endothelial dysfunction is an early indicator of sepsis and neutrophil degranulation of septic shock in surgical patients.

BACKGROUND: Stratification of the severity of infection is currently based on the Sequential Organ Failure Assessment (SOFA) score, which is difficult to calculate outside the ICU. Biomarkers could help to stratify the severity of infection in surgical patients. METHODS: Levels of ten biomarkers indicating endothelial dysfunction, 22 indicating emergency granulopoiesis, and six denoting neutrophil degranulation were compared in three groups of patients in the first 12 h after diagnosis at three Spanish hospitals. RESULTS: There were 100 patients with infection, 95 with sepsis and 57 with septic shock. Seven biomarkers indicating endothelial dysfunction (mid-regional proadrenomedullin (MR-ProADM), syndecan 1, thrombomodulin, angiopoietin 2, endothelial cell-specific molecule 1, vascular cell adhesion molecule 1 and E-selectin) had stronger associations with sepsis than infection alone. MR-ProADM had the highest odds ratio (OR) in multivariable analysis (OR 11·53, 95 per cent c.i. 4·15 to 32·08; P = 0·006) and the best area under the curve (AUC) for detecting sepsis (0·86, 95 per cent c.i. 0·80 to 0·91; P < 0·001). In a comparison of sepsis with septic shock, two biomarkers of neutrophil degranulation, proteinase 3 (OR 8·09, 1·34 to 48·91; P = 0·028) and lipocalin 2 (OR 6·62, 2·47 to 17·77; P = 0·002), had the strongest association with septic shock, but lipocalin 2 exhibited the highest AUC (0·81, 0·73 to 0·90; P < 0·001). CONCLUSION: MR-ProADM and lipocalin 2 could be alternatives to the SOFA score in the detection of sepsis and septic shock respectively in surgical patients with infection.

ANTECEDENTES: La estratificación de la gravedad de una infección se basa actualmente en la puntuación SOFA (Sequential Organ Failure Assessment), que es difícil de calcular fuera de la unidad de cuidados intensivos. Los biomarcadores podrían ayudar a estratificar la gravedad de la infección en pacientes quirúrgicos. MÉTODOS: Se compararon las concentraciones de 10 biomarcadores que denotan disfunción endotelial, 22 que indican granulopoyesis de emergencia y 6 que expresan la degranulación de neutrófilos en tres grupos de pacientes de tres hospitales españoles (100 con infección, 95 con sepsis y 57 con shock séptico) en las primeras doce horas después del diagnóstico. RESULTADOS: Siete biomarcadores que expresan disfunción endotelial (proadrenomedulina, sindecan-1, trombomodulina, angiopoyetina-2, endocan-1, molécula de adhesión endotelial 1 y E-selectina) mostraron una fuerte asociación con la sepsis en comparación con la infección aislada. La proadrenomedulina presentó el valor más alto de la razón de oportunidades (odds ratio, OR) en el análisis multivariable (OR 11,53, i.c. del 95% 4,15-32,08, P = 0,006) y la mejor área bajo la curva para detectar sepsis (AUC 0,86, i.c. del 95% 0,80-0,91, P < 0,001). En la comparación entre sepsis y shock séptico, los biomarcadores que mostraron la asociación más estrecha con el shock séptico fueron dos biomarcadores de degranulación de neutrófilos (proteinasa-3 y lipocalina-2) (OR 8,09, i.c. del 9% 1,34-48,91, P = 0,028; OR 6.62, i.c. del 95% 2,47-17,77, P = 0,002), pero la lipocalina-2 presentó la mejor AUC (0,81, i.c. del 95% 0,73-0,90, P < 0,001). CONCLUSIÓN: la proadrenomedulina y la lipocalina-2 podrían representar alternativas a la puntuación SOFA para detectar sepsis y shock séptico en pacientes quirúrgicos con infección.