Specific versus Non-Specific Immune Responses in an Invertebrate Species Evidenced by a Comparative de novo Sequencing Study

Our present understanding of the functioning and evolutionary history of invertebrate innate immunity derives mostly from studies on a few model species belonging to ecdysozoa. In particular, the characterization of signaling pathways dedicated to specific responses towards fungi and Gram-positive or Gram-negative bacteria in Drosophila melanogaster challenged our original view of a non-specific immunity in invertebrates. However, much remains to be elucidated from lophotrochozoan species. To investigate the global specificity of the immune response in the fresh-water snail Biomphalaria glabrata, we used massive Illumina sequencing of 5′-end cDNAs to compare expression profiles after challenge by Gram-positive or Gram-negative bacteria or after a yeast challenge. 5′-end cDNA sequencing of the libraries yielded over 12 millions high quality reads. To link these short reads to expressed genes, we prepared a reference transcriptomic database through automatic assembly and annotation of the 758,510 redundant sequences (ESTs, mRNAs) of B. glabrata available in public databases. Computational analysis of Illumina reads followed by multivariate analyses allowed identification of 1685 candidate transcripts differentially expressed after an immune challenge, with a two fold ratio between transcripts showing a challenge-specific expression versus a lower or non-specific differential expression. Differential expression has been validated using quantitative PCR for a subset of randomly selected candidates. Predicted functions of annotated candidates (approx. 700 unisequences) belonged to a large extend to similar functional categories or protein types. This work significantly expands upon previous gene discovery and expression studies on B. glabrata and suggests that responses to various pathogens may involve similar immune processes or signaling pathways but different genes belonging to multigenic families. These results raise the question of the importance of gene duplication and acquisition of paralog functional diversity in the evolution of specific invertebrate immune responses

Antifungal De-Escalation Is Safe in Critically Ill Patients Treated For Suspected Or Documented Invasive Candidiasis. Data From The Amarcand2 Study

International audienc

Patient factors and outcomes associated with the withdrawal or withholding of life-sustaining therapies in mechanically ventilated brain-injured patients An observational multicentre study

International audienceBackground - Knowledge of the factors associated with the decision to withdraw or withhold life support (WWLS) in brain-injured patients is limited. However, most deaths in these patients may involve such a decision. Objectives - To identify factors associated with the decision to WWLS in brain-injured patients requiring mechanical ventilation who survive the first 24 h in the ICU, and to analyse the outcomes and time to death. Design - A retrospective observational multicentre study. Settings - Twenty French ICUs in 18 university hospitals. Patients - A total of 793 mechanically ventilated brain-injured adult patients. Interventions - None. Main outcome measures - Decision to WWLS within 3 months of ICU admission, and death or Glasgow Outcome Scale (GOS) score at day 90. Results - A decision to WWLS was made in 171 patients (22%), of whom 89% were dead at day 90. Out of the 247 deaths recorded at day 90, 153 (62%) were observed after a decision to WWLS. The median time between admission and death when a decision to WWLS was made was 10 (5 to 20) days vs. 10 (5 to 26) days when no end-of-life decision was made (P < 0.924). Among the 18 patients with a decision to WWLS who were still alive at day 90, three patients (2%) had a GOS score of 2, nine patients (5%) had a GOS score of 3 and five patients (3%) a GOS score of 4. Older age, presence of one nonreactive and dilated pupil, Glasgow Coma Scale less than 7, barbiturate use, acute respiratory distress syndrome and worsening lesions on computed tomography scans were each independently associated with decisions to WWLS. Conclusion - Using a nationwide cohort of brain-injured patients, we observed a high proportion of deaths associated with an end-of-life decision. Older age and several disease severity factors were associated with the decision to WWLS