Peripheral immune progression to long COVID is associated with mitochondrial gene transcription: A meta-analysis

SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has led to millions of cases of Long COVID worldwide. Long COVID is a phenomenon characterized by persistent and debilitating mental and physical symptoms following acute infection. Despite ongoing research, trials, and considerable progress in understanding Long COVID, its exact causes remain only partially understood, with current hypotheses addressing specific aspects of the condition. We conducted one of the most comprehensive meta-analyses to date of all quality bulk RNA-seq studies worldwide from the COVID-19 pandemic and show significant mitochondrial transcript changes in the peripheral immune system of people with Long COVID, with unexpectedly low levels of intracellular viral RNA in Long COVID. This extensive analysis, which includes 26 studies and 1,272 individuals, shows that mononuclear cells, PBMC, and granulocytes from Long COVID patients exhibit significant alterations in mitochondrial genes and related processes. These findings likely represent the true transcriptomic landscape of Long COVID across diverse datasets, highlighting the long-lasting impacts of SARS-CoV-2 on peripheral immune function. In combination with other ex vivo and proteomics studies showing mitochondrial dysfunction, our results suggest critical new directions, such as the potential role of clonal hematopoiesis and infected seed cells. This work highlights the need for further investigation into the mechanisms underlying these immune changes and persistent symptoms in people with Long COVID. These findings will serve as a foundation for defining the paradigm underlying the biological mechanisms of Long COVID, driving research into the peripheral immune system, bone marrow, and mitochondria.