title: C-reactive protein exacerbates renal ischemia-reperfusion injury: are myeloid-derived suppressor cells to blame?
abstract: Myeloid-derived suppressor cells (MDSCs) are a CD11b(+)Gr1(+) population in mice that can be separated into granulocytic (g-MDSC) and monocytic (m-MDSC) subtypes based on their expression of Ly6G and Ly6C. Both MDSC subtypes are potent suppressors of T cell immunity, and their contribution has been investigated in a plethora of diseases including renal cancer, renal transplant, and chronic kidney disease. Whether MDSCs contribute to the pathogenesis of acute kidney injury (AKI) remains unknown. Herein, using human C-reactive protein (CRP) transgenic (CRPtg) and CRP-deficient mice (CRP(-/-)) subjected to bilateral renal ischemia-reperfusion injury (IRI), we confirm our earlier finding that CRP exacerbates renal IRI and show for the first time that this effect is accompanied in CRPtg mice by a shift in the balance of kidney-infiltrating MDSCs toward a suppressive Ly6G(+)Ly6C(low) g-MDSC subtype. In CRPtg mice, direct depletion of g-MDSCs (using an anti-Gr1 monoclonal antibody) reduced the albuminuria caused by renal IRI, confirming they play a deleterious role. Remarkably, treatment of CRPtg mice with an antisense oligonucleotide that specifically blocks the human CRP acute-phase response also led to a reduction in renal g-MDSC numbers and improved albuminuria after renal IRI. Our study in CRPtg mice provides new evidence that MDSCs participate in the pathogenesis of renal IRI and shows that their pharmacological depletion is beneficial. If ongoing investigations confirm that CRP is an endogenous regulator of MDSCs in CRPtg mice, and if this action is recapitulated in humans, then targeting CRP or/and MDSCs might offer a new approach for the treatment of AKI.
authors.affiliation: Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Pegues
authors.affiliation: Department of Cellular, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Ian L
authors.initials: IL
authors.lastname: McWilliams
authors.affiliation: Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and AlexSzalai@uab.edu.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Szalai
mesh_terms: D058186:Acute Kidney Injury / Q000139:chemically induced / Q000473:pathology; D000818:Animals; D000950:Antigens, Ly / Q000096:biosynthesis / Q000235:genetics; D002097:C-Reactive Protein / Q000235:genetics / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D006098:Granulocytes / Q000187:drug effects / Q000473:pathology; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000187:drug effects / Q000473:pathology; D022423:Myeloid Cells / Q000473:pathology*; D015427:Reperfusion Injury / Q000139:chemically induced* / Q000473:pathology; D013601:T-Lymphocytes
chemical_list: D000950:Antigens, Ly; C480309:Ly6G antigen, mouse; D002097:C-Reactive Protein
keywords: acute phase proteins; innate immunity; pentraxin