Acquired Brain Injury Following Sepsis

The ROS/TXNIP/NLRP3 pathway mediates LPS-induced microglial inflammatory response

BACKGROUND

Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction activated by microglia. The potential pathological changes of SAE are complex, and the cellular pathophysiological characteristics remains unclear. This study aims to explore the ROS/TXNIP/NLRP3 pathway mediated lipopolysaccharide (LPS)-induced inflammatory response in microglia.

METHODS

BV-2 cells were pre-incubated with 10 μM N-acetyl-L-cysteine (NAC) for 2 h, which were then reacted with 1 μg/mL LPS for 24 h. Western blot assay examined the protein levels of IBA1, CD68, TXNIP, NLRP3, ASC, and Cleaved Caspase-1 in BV-2 cells. The contents of inflammatory factor were detected by ELISA assay. The co-immunoprecipitation assay examined the interaction between TXNIP and NLRP3.

RESULTS

LPS was confirmed to promote the positive expressions of IBA1 and CD68 in BV-2 cells. The further experiments indicated that LPS enhanced ROS production and NLRP3 inflammasome activation in BV-2 cells. Moreover, we also found that NAC partially reversed the facilitation of LPS on the levels of ROS, IL-1β, IL-18, TXNIP, NLRP3, ASC, and Cleaved Caspase-1 in BV-2 cells. NAC treatment also notably alleviated the interaction between TXNIP and NLRP3 in BV-2 cells.

CONCLUSION

ROS inhibition mediated NLRP3 signaling inactivation by decreasing TXNIP expression.

CLINICAL PHENOTYPES OF SEPSIS-ASSOCIATED ENCEPHALOPATHY: A RETROSPECTIVE COHORT STUDY

ABSTRACT

Background: Sepsis-associated encephalopathy (SAE) is a dysfunction of the central nervous system experienced during sepsis with variable clinical and pathophysiologic features. We sought to identify distinct SAE phenotypes in relation to clinical outcomes. Methods: The Medical Information Mart for Intensive Care IV (MIMIC-IV) database and the eICU database were used to conduct a retrospective cohort study. Adult sepsis patients were included and SAE was defined as having a Glasgow Coma Scale (GCS) score ˂15 or delirium. The following our clinical phenotypes were defined as: ischemic-hypoxic, metabolic, mixed (ischemic-hypoxic and metabolic), and unclassified. The primary outcome was in-hospital mortality. Results: The study enrolled 4,120 sepsis patients, 2,239 from MIMIC-IV (including 1,489 patients with SAE, 67%), and 1,881 from eICU (1,291, 69%). For the SAE cohort, 2,780 patients in total were enrolled (median age, 67 years; interquartile range, 56-76.8; 1,589 (57%) were male; median GCS score was 12 [8-14]; median Sequential Organ Failure Assessment score was 6 [4-9]). The SAE phenotype distributions between the MIMIC-IV and eICU cohorts were as follows (39% vs. 35% ischemic-hypoxic, P = 0.043; 38% vs. 40% metabolic, P = 0.239; 15% vs. 15% mixed, P = 0.972; 38% vs. 40% unclassified, P = 0.471). For the overall cohort, the in-hospital mortality for patients with ischemic-hypoxic, metabolic, mixed, or unclassified phenotypes was 33.9% (95% confidence interval, 0.3-0.37), 28.4% (0.26-0.31), 41.5% (0.37-0.46), and 14.2% (0.12-0.16), respectively. In the multivariable logistic analysis, the mixed phenotype was associated with the highest risk of in-hospital mortality after adjusting for age, sex, GCS, and modified Sequential Organ Failure Assessment score (adjusted odds ratio, 2.11; 95% confidence interval, 1.67-2.67; P < 0.001). Conclusions: Four SAE phenotypes had different clinical outcomes. The mixed phenotype had the worst outcomes. Further understanding of these phenotypes in sepsis may improve trial design and targeted SAE management.

Expression of MicroRNAs in Sepsis-Related Organ Dysfunction: A Systematic Review

Sepsis is a critical condition characterized by increased levels of pro-inflammatory cytokines and proliferating cells such as neutrophils and macrophages in response to microbial pathogens. Such processes lead to an abnormal inflammatory response and multi-organ failure. MicroRNAs (miRNA) are single-stranded non-coding RNAs with the function of gene regulation. This means that miRNAs are involved in multiple intracellular pathways and thus contribute to or inhibit inflammation. As a result, their variable expression in different tissues and organs may play a key role in regulating the pathophysiological events of sepsis. Thanks to this property, miRNAs may serve as potential diagnostic and prognostic biomarkers in such life-threatening events. In this narrative review, we collect the results of recent studies on the expression of miRNAs in heart, blood, lung, liver, brain, and kidney during sepsis and the molecular processes in which they are involved. In reviewing the literature, we find at least 122 miRNAs and signaling pathways involved in sepsis-related organ dysfunction. This may help clinicians to detect, prevent, and treat sepsis-related organ failures early, although further studies are needed to deepen the knowledge of their potential contribution.