1
|
Vaivoda R, Vaine C, Boerstler C, Galloway K, Christmas P. CYP4F18-Deficient Neutrophils Exhibit Increased Chemotaxis to Complement Component C5a. J Immunol Res 2015; 2015:250456. [PMID: 26613087 PMCID: PMC4647059 DOI: 10.1155/2015/250456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/27/2015] [Accepted: 10/18/2015] [Indexed: 01/08/2023] Open
Abstract
CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.9-2.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies.
Collapse
Affiliation(s)
- Rachel Vaivoda
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Christine Vaine
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | | | - Kristy Galloway
- Department of Biology, Radford University, Radford, VA 24142, USA
| | - Peter Christmas
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Department of Biology, Radford University, Radford, VA 24142, USA
| |
Collapse
|
2
|
Winslow V, Vaivoda R, Vasilyev A, Dombkowski D, Douaidy K, Stark C, Drake J, Guilliams E, Choudhary D, Preffer F, Stoilov I, Christmas P. Altered leukotriene B4 metabolism in CYP4F18-deficient mice does not impact inflammation following renal ischemia. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:868-79. [PMID: 24632148 DOI: 10.1016/j.bbalip.2014.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 02/18/2014] [Accepted: 03/05/2014] [Indexed: 01/26/2023]
Abstract
Inflammatory responses to infection and injury must be restrained and negatively regulated to minimize damage to host tissue. One proposed mechanism involves enzymatic inactivation of the pro-inflammatory mediator leukotriene B4, but it is difficult to dissect the roles of various metabolic enzymes and pathways. A primary candidate for a regulatory pathway is omega oxidation of leukotriene B4 in neutrophils, presumptively by CYP4F3A in humans and CYP4F18 in mice. This pathway generates ω, ω-1, and ω-2 hydroxylated products of leukotriene B4, depending on species. We created mouse models targeting exons 8 and 9 of the Cyp4f18 allele that allows both conventional and conditional knockouts of Cyp4f18. Neutrophils from wild-type mice convert leukotriene B4 to 19-hydroxy leukotriene B4, and to a lesser extent 18-hydroxy leukotriene B4, whereas these products were not detected in neutrophils from conventional Cyp4f18 knockouts. A mouse model of renal ischemia-reperfusion injury was used to investigate the consequences of loss of CYP4F18 in vivo. There were no significant changes in infiltration of neutrophils and other leukocytes into kidney tissue as determined by flow cytometry and immunohistochemistry, or renal injury as assessed by histological scoring and measurement of blood urea nitrogen. It is concluded that CYP4F18 is necessary for omega oxidation of leukotriene B4 in neutrophils, and is not compensated by other CYP enzymes, but loss of this metabolic pathway is not sufficient to impact inflammation and injury following renal ischemia-reperfusion in mice.
Collapse
Affiliation(s)
- Valeria Winslow
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Rachel Vaivoda
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Aleksandr Vasilyev
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - David Dombkowski
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Karim Douaidy
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Christopher Stark
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Justin Drake
- Biology Department, Radford University, Radford, VA 24142, USA
| | - Evin Guilliams
- Biology Department, Radford University, Radford, VA 24142, USA
| | - Dharamainder Choudhary
- Department of Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Frederic Preffer
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Ivaylo Stoilov
- Department of Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Peter Christmas
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, MA 02129, USA; Biology Department, Radford University, Radford, VA 24142, USA.
| |
Collapse
|