Sefik et al. (2026)
- Authors: Esen Sefik, Rihao Qu, Caroline Junqueira, Eleanna Kaffe, Haris Mirza, Jun Zhao, J. Richard Brewer, Ailin Han, Holly R. Steach, Benjamin Israelow, Holly N. Blackburn, Sofia Velazquez, Akiko Iwasaki
- Institutes: Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT, USA, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA, USA
- Publisher: Clinical Immunology
- Link: DOI
Summary
This review consolidates the evidence that Long COVID is driven by a failure of the innate immune system to return to a baseline state after infection. By identifying specific persistent inflammatory triggers in lung macrophages, it opens the door for targeted therapies that focus on ‘resolving’ inflammation rather than just suppressing it. This paradigm shift suggests that treatments like inflammasome inhibitors could potentially halt the chronic cycle of symptoms in PASC patients.
What was researched?
This narrative review examined the hypothesis that Post-Acute Sequelae of COVID-19 (PASC) is fundamentally a disorder characterized by the failure of the innate immune system to resolve inflammation.
Why was it researched?
Despite the clearance of active infection, 10-20% of patients experience chronic symptoms, necessitating an investigation into why the immune-inflammatory response remains pathologically sustained in these individuals.
How was it researched?
The authors synthesized findings from human patient cohorts and advanced humanized mouse models (MISTRG6-hACE2) to track the transition from acute infection to chronic inflammatory states.
What has been found?
The research highlights that lung-resident human macrophages can harbor viral RNA and maintain active inflammasomes, leading to the continuous release of pro-inflammatory cytokines like IL-1 and IL-18. This state of ‘impaired resolution’ is further driven by a sustained interferon response and high levels of specific IgG antibodies that may enhance macrophage infection. Blocking these pathways with Remdesivir 💊 or anti-IFNAR2 💊 in models was shown to attenuate overactive immune responses.
Discussion
The review discusses the tension between viral persistence and autoimmunity, suggesting that innate immune ‘memory’ and persistent viral products prevent the natural shutdown of the inflammatory cascade. A significant finding is that inhibiting the NLRP3 inflammasome 💊 can reverse lung pathology but may also lead to the release of infectious virus, suggesting a delicate balance in treatment.
Conclusion & Future Work
Long COVID is defined by persisting immunological dysfunction where the innate immune system fails to ‘downgrade’ after the acute phase. Future research should prioritize pro-resolving therapies and clinical trials targeting the inflammasome-macrophage axis.