Identification of inflammatory clusters in long-COVID through analysis of plasma biomarker levels

Front Immunol. 2024 Apr 30:15:1385858. doi: 10.3389/fimmu.2024.1385858. eCollection 2024.

Abstract

Mechanisms underlying long COVID remain poorly understood. Patterns of immunological responses in individuals with long COVID may provide insight into clinical phenotypes. Here we aimed to identify these immunological patterns and study the inflammatory processes ongoing in individuals with long COVID. We applied an unsupervised hierarchical clustering approach to analyze plasma levels of 42 biomarkers measured in individuals with long COVID. Logistic regression models were used to explore associations between biomarker clusters, clinical variables, and symptom phenotypes. In 101 individuals, we identified three inflammatory clusters: a limited immune activation cluster, an innate immune activation cluster, and a systemic immune activation cluster. Membership in these inflammatory clusters did not correlate with individual symptoms or symptom phenotypes, but was associated with clinical variables including age, BMI, and vaccination status. Differences in serologic responses between clusters were also observed. Our results indicate that clinical variables of individuals with long COVID are associated with their inflammatory profiles and can provide insight into the ongoing immune responses.

Keywords: immune dysregulation; inflammatory clusters; long COVID; post-acute sequelae of SARS-CoV-2; symptom clusters.

MeSH terms

  • Adult
  • Aged
  • Biomarkers* / blood
  • COVID-19* / blood
  • COVID-19* / immunology
  • Cluster Analysis
  • Female
  • Humans
  • Inflammation* / blood
  • Inflammation* / immunology
  • Male
  • Middle Aged
  • Post-Acute COVID-19 Syndrome
  • SARS-CoV-2* / immunology

Grants and funding

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.