AUTHOR=Zemtsovski Jan D. , Tumpara Srinu , Schmidt Sonja , Vijayan Vijith , Klos Andreas , Laudeley Robert , Held Julia , Immenschuh Stephan , Wurm Florian M. , Welte Tobias , Haller Hermann , Janciauskiene Sabina , Shushakova Nelli 

TITLE=Alpha1-antitrypsin improves survival in murine abdominal sepsis model by decreasing inflammation and sequestration of free heme

JOURNAL=Frontiers in Immunology

VOLUME=Volume 15 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1368040

DOI=10.3389/fimmu.2024.1368040

ISSN=1664-3224

ABSTRACT=Background: Excessive inflammation, hemolysis, and accumulation of labile heme play an essential role in the pathophysiology of multiorgan dysfunction syndrome (MODS) in sepsis. Alpha1antitrypsin (AAT), an acute phase protein with heme binding capacity, is one of the essential modulators of host responses to inflammation. In this study, we evaluate the putative protective effect of AAT against MODS and mortality in a mouse model of polymicrobial abdominal sepsis. Methods: Polymicrobial abdominal sepsis was induced in C57BL6N mice by cecal-ligation-andpuncture (CLP). Immediately after CLP surgery, mice were treated intraperitoneally with 3 different forms of human AAT: plasma-derived native (nAAT), oxidized nAAT (oxAAT), or recombinant (recAAT), or were injected with vehicle. Sham-operated mice served as controls. We assessed mouse survival, bacterial load, kidney and liver function, immune cell profiles, cytokines/chemokines, and free (labile) heme levels. In parallel, in vitro experiments were carried out with resident peritoneal macrophages (MPMΦ) and mouse peritoneal mesothelial cells (MPMC).Results: All AAT preparations used reduced mortality in septic mice. Treatment with AAT significantly reduced plasma lactate dehydrogenase and s-creatinine levels, vascular leakage and systemic inflammation. Specifically AAT reduced intraperitoneal accumulation of free heme, production of cytokines/chemokines, and neutrophil infiltration into the peritoneal cavity compared to septic mice not treated with AAT. In vitro experiments performed with mouse peritoneal mesothelial cells (MPMC) and primary peritoneal macrophages (MPMΦ) confirmed that AAT not only significantly decreases lipopolysaccharide (LPS)-induced pro-inflammatory cell activation but also prevents the enhancement of cellular responses to LPS by free heme. In addition, AAT inhibits cell death caused by free heme in vitro.Data from the septic CLP mouse model suggest that intraperitoneal AAT treatment alone is sufficient to improve sepsis-associated organ dysfunctions, to preserve endothelial barrier function, and to reduce mortality, likely by preventing of hyper-inflammatory responses and by neutralizing of free heme.