Anti-miR-93-5p therapy prolongs sepsis survival by restoring the peripheral immune response

Sepsis remains a leading cause of death and currently has no pathogenesis-specific therapy. Hampered progress is partly due to the lack of insight into deep mechanistic processes. Deciphering the functions of microRNAs in sepsis pathogeny became a dynamic research topic in the last decade. To screen for new microRNA targets for sepsis therapeutics, we used human samples: microRNA array data from peripheral blood mononuclear cells (PBMCs) from sepsis patients and controls, whole blood samples from sepsis survivors; and multiple animal models: mouse cecum ligation-puncture (CLP)-induced sepsis, mouse viral microRNA challenge, and baboon Gram-positive and Gram-negative sepsis models. miR-93-5p met the criteria for a therapeutic target, being overexpressed in baboons which died early after induction of sepsis and downregulated in humans who survived after sepsis. Therapeutically, inhibiting miR-93-5p prolonged the overall survival of mice with CLP-induced sepsis, with a stronger effect in old mice. Mechanistically, anti-miR-93-5p therapy reduced inflammatory monocytes and increased circulating effector memory T cells, especially CD4+ subset. Ago2-immunoprecipitation in miR-93-knockout T cells identified important regulatory receptors, CD28 and CD160, as direct miR-93-5p target genes. In conclusion, miR-93-5p is a potential therapeutic target in sepsis in the elderly through its regulation of both innate and adaptive immunity. We applied the Ago2-RIP Chip (Ribonucleoprotein ImmunoPrecipitation followed by microarray analysis) to identify miR-93-5p target mRNAs. This methodology uses beads coupled to either anti-Ago2 antibody (or an IgG control) to pull down the RISC complex together with any miRNA-interacting mRNAs. To define target genes of miR-93-5p, we assessed mRNA transcripts enriched in the Ago2-IP fraction of JURKAT parental cells or control cells (where miR-93-5p is present) but not in the two KO clones (where miR-93-5p is absent) by microarray Pulldown of RISC complex via Ago2 in Jurkat miR-93 wildtype and knockout cells in order to define miR-93 targetome