Infections are an important cause of morbidity and mortality in patients with decompensated cirrhosis and ascites. Hypothesizing that innate immune dysfunction contributes to susceptibility to infection, we assessed ascitic fluid macrophage phenotype and function. The expression of complement receptor of the immunoglobulin superfamily (CRIg) and CCR2 defined two phenotypically and functionally distinct peritoneal macrophage subpopulations. The proportion of CRIghi macrophages differed between patients and in the same patient over time, and a high proportion of CRIghi macrophages was associated with reduced disease severity (model for end-stage liver disease) score. As compared with CRIglo macrophages, CRIghi macrophages were highly phagocytic and displayed enhanced antimicrobial effector activity. Transcriptional profiling by RNA sequencing and comparison with human macrophage and murine peritoneal macrophage expression signatures highlighted similarities among CRIghi cells, human macrophages, and mouse F4/80hi resident peritoneal macrophages and among CRIglo macrophages, human monocytes, and mouse F4/80lo monocyte-derived peritoneal macrophages. These data suggest that CRIghi and CRIglo macrophages may represent a tissue-resident population and a monocyte-derived population, respectively. In conclusion, ascites fluid macrophage subset distribution and phagocytic capacity is highly variable among patients with chronic liver disease. Regulating the numbers and/or functions of these macrophage populations could provide therapeutic opportunities in cirrhotic patients.
Katharine M. Irvine, Xuan Banh, Victoria L. Gadd, Kyle K. Wojcik, Juliana K. Ariffin, Sara Jose, Samuel Lukowski, Gregory J. Baillie, Matthew J. Sweet, Elizabeth E. Powell
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. All accepted letters will be posted on our website within one week of acceptance. We reserve the right to edit any letter for length, content, and clarity. Authors of all accepted letters will be asked to preview any changes. Authors will be notified by e-mail if their letters were not accepted. As this is a final decision, no appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.