Biliverdin reductase A (BVRA) is a multifunctional protein highly expressed by macrophages.

Its enzymatic activity acts downstream of heme catabolism, converting biliverdin into bilirubin. Both end-products are physiologic ligands of the nuclear Aryl hydrocarbon receptor, an immunoregulatory component of the transcriptional stress and damage control network that promotes disease tolerance to infection.

Bilitolerance is aimed to address whether BVRA promotes disease tolerance.