# LEF1-AS1 Deregulation in the Peripheral Blood of Patients with Persistent Post-COVID Symptoms

## TL;DR

This study identifies LEF1-AS1 as a potential biomarker in the blood of patients with long-term symptoms after COVID-19.

## Contribution

The novel finding is the downregulation of LEF1-AS1 in peripheral blood cells of long COVID patients.

## Key findings

- LEF1-AS1 is downregulated in PBMCs of symptomatic long COVID patients.
- LEF1-AS1 isoforms and sense transcript levels correlate with clinical markers.
- miR-144-3p and other lncRNAs showed no significant differences between symptomatic and asymptomatic patients.

## Abstract

Long COVID denotes the persistence of symptoms after acute SARS-CoV-2 infection lasting for at least two months without another identifiable cause. Affecting an estimated 15% of COVID-19 patients, long COVID manifests in a wide range of symptoms. Despite extensive research on its one-year effects, limited data exist beyond 12 months. Due to the different manifestations of long COVID, its diagnosis can be challenging. Identifying potential mechanistic contributors and biomarkers would be highly valuable. Recent studies have highlighted the potential of noncoding RNAs (ncRNAs) as biomarkers for disease stratification in COVID-19. Specifically, we have recently identified miR-144-3p and a subset of lncRNAs as candidates for assessing disease severity and outcomes in COVID-19. This nested case–control study extends such investigations to 98 long COVID patients recruited 18 months after hospitalization, exploring the relationship between circulating ncRNA expression and persistent symptoms. While miR-144-3p, HCG18, and lncCEACAM21 expression did not differ between symptomatic and asymptomatic patients, LEF1-AS1 was downregulated in the peripheral blood mononuclear cells (PBMCs) of symptomatic patients. Of note, multiple LEF1-AS1 isoforms and LEF1 sense transcript levels were reduced and negatively correlated with relevant clinical markers. While further studies are needed, our discoveries offer new perspectives on the diagnosis and management of persistent long COVID.