Gene expression profile of immune response markers associated with long COVID and its clinical aspects in a cohort from northern Brazil.

BACKGROUND: Long COVID is characterized by a multisystemic, and complex disease and current efforts are focused on the search for biomarkers associated with clinical outcomes. OBJECTIVE: In this study, we evaluated the gene expression of 15 biomarkers and their relationship with the clinical aspects of the condition. METHODS: c-DNA samples from 15 patients with long COVID, 15 patients recovered and without sequelae (RWS), and 15 patients with symptomatic acute COVID-19 were analyzed. The relative expression of genes was determined by the 2-ΔΔCT method from real-time PCR. Sociodemographic and clinical data of interest were extracted from medical records. RESULTS: Of the 15 biomarkers, only the expression of TREX1, FOXP3, MYD88 and FASL was not associated with long COVID. The genes IRF7, IRF3, and IFI16 performed best as biomarkers of long COVID (AUC ≥ 0.90, p ≤ 0.05). Except for MDA5 and RIG-1 genes, the expression of the other eight genes was associated with the presence of comorbidities, medication use, and complaints of fever, abdominal pain, eye pain, and headache (H > 9.0; p ≤ 0.05). IRF3 expression was specifically associated with long COVID when compared to acute COVID (med.: 41.2; IQR: 116.20; p: 0.0036). CONCLUSION: Our results suggest that classical immune response genes are upregulated in long COVID and that certain clinical aspects of the disease may influence the expression profile of the studied genes.