Adeno-Associated Virus-Based Hemopexin Therapy Attenuates Sepsis-Induced Kidney Injury in a Humanized Mouse Model of Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive hemoglobinopathy caused by mutations in the β-globin gene, leading to the production of hemoglobin S (HbS). Under low oxygen tension, HbS polymerizes, deforming red blood cells (RBCs) into the characteristic sickle shape. This abnormal morphology promotes vaso-occlusion, chronic hemolysis, and progressive multi-organ damage. Individuals with SCD are highly susceptible to severe infections, including sepsis, due to functional asplenia and immune dysregulation. Sepsis can trigger acute kidney injury (AKI), a severe complication that accelerates disease progression and increases morbidity and mortality. However, the mechanisms underlying septic AKI in SCD remain poorly understood. We previously demonstrated that transgenic SCD mice are more sensitive to septic AKI than non-sickling mice and that free heme plays a central role in its pathogenesis. Notably, administration of purified human hemopexin (Hx) mitigates these effects by scavenging excess heme. In this study, we investigated whether genetic overexpression of Hx could reduce septic AKI in homozygous SCD (SS; Townes model) mice. SS mice received retroorbital injections of an adeno-associated virus expressing the Hx gene (rAAV8-Hx) or a control virus expressing eGFP (rAAV8-eGFP). Reduced basal heme levels in AAV-Hx-treated mice confirmed successful Hx overexpression. Both AAV-Hx- and AAV-eGFP-treated mice were subjected to either a sham operation or cecal ligation and puncture (CLP), a preclinical model of polymicrobial sepsis. Kidney function was assessed using transdermal glomerular filtration rate (GFR) measurements, and biomarkers of AKI, oxidative stress, and inflammation were analyzed. Our results demonstrate that AAV-Hx treatment significantly increased hepatic Hx expression without causing liver injury or mortality. Following low-grade CLP (<45% cecal ligation with a single puncture using a 21-gauge needle), AAV-Hx-treated mice exhibited 100% survival, compared to 62.5% in AAV-eGFP-treated mice. Hx overexpression significantly reduced sepsis-induced increases in plasma heme and ferritin levels compared to controls. Additionally, AAV-eGFP-treated mice exhibited CLP-induced reductions in GFR and elevations in AKI biomarkers, whereas AAV-Hx-treated mice were protected from CLP-induced kidney injury. In conclusion, these findings highlight the therapeutic potential of Hx overexpression in mitigating septic AKI by targeting free heme, offering a promising strategy for individuals with SCD. Funding: NIH R01 HL151735 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.