EMERGING ROLE OF EXTRACELLULAR RNA IN INNATE IMMUNITY, SEPSIS, AND TRAUMA

Cytosolic nucleic acid sensing as driver of critical illness: mechanisms and advances in therapy

Nucleic acids from both self- and non-self-sources act as vital danger signals that trigger immune responses. Critical illnesses such as acute respiratory distress syndrome, sepsis, trauma and ischemia lead to the aberrant cytosolic accumulation and massive release of nucleic acids that are detected by antiviral innate immune receptors in the endosome or cytosol. Activation of receptors for deoxyribonucleic acids and ribonucleic acids triggers inflammation, a major contributor to morbidity and mortality in critically ill patients. In the past decade, there has been growing recognition of the therapeutic potential of targeting nucleic acid sensing in critical care. This review summarizes current knowledge of nucleic acid sensing in acute respiratory distress syndrome, sepsis, trauma and ischemia. Given the extensive research on nucleic acid sensing in common pathological conditions like cancer, autoimmune disorders, metabolic disorders and aging, we provide a comprehensive summary of nucleic acid sensing beyond critical illness to offer insights that may inform its role in critical conditions. Additionally, we discuss potential therapeutic strategies that specifically target nucleic acid sensing. By examining nucleic acid sources, sensor activation and function, as well as the impact of regulating these pathways across various acute diseases, we highlight the driving role of nucleic acid sensing in critical illness.

Plasma microRNA biomarkers for multi-organ injury prediction in trauma patients

Trauma remains a leading cause of morbidity and mortality in part due to secondary multi-organ injury. However, our ability to predict the downstream pathophysiology and adverse outcomes of trauma is limited. Here, we select a panel of microRNAs (miRNAs) biomarker candidates based on plasma RNA-Seq analysis of trauma patients and the unique pro-inflammatory nucleotide motif structures identified via a machine learning-guided computer exhaustive search algorithm. We test the panel of plasma miRNAs for their association with various trauma pathophysiological markers and their ability to predict organ injury and immune responses to trauma. We find a marked elevation of these plasma miRNAs as well as multiple inflammatory and organ injury factors at time of admission in a cohort of 48 blunt trauma patients. The plasma levels of these miRNA biomarkers are highly associated with multiple pathophysiological markers known for organ injury, coagulopathy, endothelial activation, and innate inflammation. AUROC analyses indicate that these miRNA biomarkers possess strong abilities to distinguish trauma severity, brain and liver injuries, metabolic acidosis, coagulopathy, and innate inflammation. These observations offer insights into potential values of the selected plasma miRNAs in prediction of trauma pathophysiological risk and clinical outcomes.

Harnessing Extracellular microRNAs for Diagnostics and Therapeutics in Acute Systemic Inflammation

Micro-ribonucleic acids (miRNAs) are small sequences of genetic materials that are primarily transcribed from the intronic regions of deoxyribonucleic acid (DNAs), and they are pivotal in regulating messenger RNA (mRNA) expression. miRNAs were first discovered to regulate mRNAs of the same cell in which they were transcribed. Recent studies have unveiled their ability to traverse cells, either encapsulated in vesicles or freely bound to proteins, influencing distant recipient cells. Activities of extracellular miRNAs have been observed during acute inflammation in clinically relevant pathologies, such as sepsis, shock, trauma, and ischemia/reperfusion (I/R) injuries. This review comprehensively explores the activity of miRNAs during acute inflammation as well as the mechanisms of their extracellular transport and activity. Evaluating the potential of extracellular miRNAs as diagnostic biomarkers and therapeutic targets in acute inflammation represents a critical aspect of this review. Finally, this review concludes with novel concepts of miRNA activity in the context of alleviating inflammation, delivering potential future directions to advance the field of miRNA therapeutics.