Pharmacological targeting of the hyper-inflammatory response to SARS-CoV-2-infected K18-hACE2 mice using a cluster of differentiation 36 receptor modulator.

This study investigated whether hexarelin — a synthetic peptide ligand targeting the CD36 receptor — could reduce the hyper-inflammatory response associated with severe SARS-CoV-2 infection. Using the K18-hACE2 transgenic mouse model, which expresses the human ACE2 receptor and is widely used to study COVID-19 pathology, the researchers examined how SARS-CoV-2 infection drives alveolar macrophages toward a pro-inflammatory phenotype and whether CD36 modulation could interrupt this process. The study found that CD36 signaling appears to play a regulatory role in macrophage-driven cytokine overproduction — the so-called "cytokine storm" — and that hexarelin treatment showed potential for blunting this response, thereby potentially limiting progression to acute respiratory distress syndrome (ARDS). The study is limited by its reliance on an animal model, meaning results may not translate directly to human patients. The transgenic mouse system, while a useful proxy for human COVID-19, does not fully recapitulate human immunological complexity. No clinical data in humans were presented. The authors acknowledge that ARDS from SARS-CoV-2 remains an unmet therapeutic need and position hexarelin as a candidate for further investigation.

Why this grade: The study was conducted entirely in a K18-hACE2 transgenic mouse model with no human subjects or clinical trial data, limiting its direct applicability to human outcomes.