# MicroRNA Profiling as a Novel Tool in the Diagnostics of Late-Onset Neonatal Sepsis: A Scoping Review

## TL;DR

This review explores how microRNA expression changes in neonates with late-onset sepsis, suggesting they could help diagnose the condition more quickly.

## Contribution

The study identifies specific miRNAs that are consistently altered in neonatal sepsis, offering potential biomarkers for early diagnosis.

## Key findings

- Neonates with late-onset sepsis show altered miRNA expression compared to controls.
- Several miRNAs, including miR-181a and miR-16, are consistently up- or downregulated in LOS cases.
- Current findings suggest miRNAs could serve as biomarkers but require validation in larger studies.

## Abstract

What are the main findings?
Many studies show altered expression of miRNAs in septic neonates compared to controls.Existing studies are heterogenous, showing either up- or downregulation of specific miRNAs.

Many studies show altered expression of miRNAs in septic neonates compared to controls.

Existing studies are heterogenous, showing either up- or downregulation of specific miRNAs.

What are the implications of the main findings?
MicroRNAs as novel biomarkers could play an important role in prompt and accurate diagnosis of late-onset sepsis (LOS), offering neonatologists a valuable tool.These findings require validation in larger cohorts and/or randomized control trials to determine their clinical utility.

MicroRNAs as novel biomarkers could play an important role in prompt and accurate diagnosis of late-onset sepsis (LOS), offering neonatologists a valuable tool.

These findings require validation in larger cohorts and/or randomized control trials to determine their clinical utility.

Background/Objectives: The incidence of late-onset sepsis (LOS) has increased with improved survival rates in premature infants. Blood culture, the diagnostic “gold standard”, requires at least 36–72 h for results, leading to empiric antibiotic use and potential resistance. MicroRNAs (miRNAs) have emerged as promising biomarkers for sepsis in adults, but their role in neonatal LOS remains unclear. The aim of this scoping review is to identify the miRNA expression profiles of bacterial LOS in neonates. Methods: A scoping review of the literature was performed between 1 November 2023 and 31 December 2024. Results: Twelve studies fulfilled our criteria and were included in the review. Despite the considerable heterogeneity among the studies, most focused on detecting and quantifying serum microRNAs using real-time PCR, while some examined correlations with other biomarkers, such as CRP. The few microRNAs identified as common across multiple studies showed similar patterns of regulation in LOS cases. Compared to controls (no LOS), neonates with LOS exhibited significant alterations in miRNA expression. More precisely, in LOS, miRNA-181a, miRNA-23b, miRNA-181b5p, miRNA-21-5p, miRNA-34a5p, miRNA-199a3p, miRNA-1184 and miRNA-1295p were downregulated, while miRNA-16, miRNA-146a, miRNA-101, miRNA-187, miRNA-21, miRNA-15a/16 and miRNA-455-5p were upregulated. Conclusions: Currently, there is limited data regarding miRNA expression in LOS. Many studies showed altered expression of specific miRNAs in septic neonates; however, these observations need further validation in larger cohorts and/or randomized controlled trials to confirm their diagnostic potential.