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Preprint WatchModerateOctober 23rd, 2026

Mechanisms of sex differences in acute and long COVID sequelae in mice

Liu, J. A.; Chaulagain, S.; Xie, X.; Creisher, P. S.; Zhong, W.; Zhang, T.; Taddese, M.; Shi, K.; Park, H.-S.; Hcnir, H.; Arnold, A. P.; Baric, R. S.; Barahona, N. B.; Engler-Chiurazzi, E. B.; Zwezdaryk, K. J.; Thio, C. L.; Balagopal, A.; Harkema, J. R.; Thompson, E. A.; Pekosz, A.; Cox, A. L.; Klein, S. L.

Infection-induced upregulation of X-linked Tlr7 sustains inflammation and cognitive impairment in post-acute sequelae of COVID-19, and pharmacological TLR7 inhibition during the post-acute phase reverses it.

Moderate contradiction

1 prior failure

Two documented clinical failures match this mechanism, or a single Phase 3 failure is on record.

This preprint reports that sustained X-linked TLR7 activity mediates inflammation and cognitive impairment in a mouse model of post-acute sequelae of COVID-19, and that inhibiting TLR7 during the post-acute phase reverses those outcomes. Claidex holds one TLR7 programme failure, enpatoran-tlr7-tlr8-dermatomyositis-polymyositis-phase2-futility, a Phase 2 study of a dual TLR7 and TLR8 inhibitor stopped for futility in dermatomyositis and polymyositis. The flag is MODERATE because that documented failure is an efficacy failure. The two settings differ in disease and in timing, so the contradiction is partial, but any new TLR7 inhibition programme should state why a target that did not separate from control in an interferon-driven autoimmune myopathy would separate in a post-viral syndrome.

Abstract excerpt

Males suffer more severe outcomes during acute COVID-19 and a greater proportion of females develop post-acute sequalae of COVID-19 (PASC). To identify mechanisms of PASC, mice were infected with SARS-CoV-2 and viral, inflammatory, and behavioral outcomes were evaluated through 84 days post-infection. Sex differences were not observed in virus replication or persistence of viral RNA in pulmonary or extrapulmonary tissues. After infectious virus clearance, females exhibited persistent deficits in spatial working and recognition memory, and greater frequencies of inflammatory myeloid cells, neuroinflammation, and dysregulated T cells, including Tregs. Sex differences in persistent inflammation and cognitive impairments during PASC were mediated by the presence of two X chromosomes and infection-induced upregulation of the X-linked genes Xist and Tlr7, which was reversed by pharmacological inhibition of TLR7 activity during the PASC phase. Sustained X-linked TLR7-mediated inflammation underlies how the burden of PASC is greater for females and provides a therapeutic target.

Matching Claidex post-mortems

1 of 1 indexed

This is an automated contradiction flag, not an editorial judgment on the preprint's quality. Flags identify where the preclinical literature and the clinical failure record diverge.