PWE-114 Modulation of non-canonical nfkb pathways may underlie the anti-inflammatory, resolution-like activation of circulating cd14hi monocytes in hyper-acute liver failure
Authors: RD Abeles, CG Antoniades, DL Shawcross, W Khamri, GK Manakkat-Vijay, W Bernal, JA Wendon, D Vergani
Journal: Gut (2015)

<h3>Introduction</h3> 3 monocyte (Mφ) subsets exist: CD14<sup>hi</sup>/CD16<sup>-</sup>, CD14<sup>hi</sup>/CD16<sup>+</sup>and CD14<sup>lo</sup>/CD16<sup>+</sup>. Reduced CD14<sup>hi</sup>Mφ surface expression of HLA-DR and failure to secrete pro-inflammatory cytokines in response to lipopolysaccharide (LPS) are thought to contribute to high infection rates and increased morbidity and mortality in Acute Liver Failure (ALF). We wanted to define CD14<sup>hi</sup>. We investigated CD14<sup>hi</sup>Mφ phenotype and function and related gene expression profiles in hyperacute ALF (hALF). <h3>Method</h3> Admission blood samples were obtained from 45 patients with hALF and from 19 healthy controls (HC). Mφ were phenotyped by flow cytometry (FCM) using fluorochrome-labelled antibodies to CD14, CD16, HLA-DR, HLA-DQ, CD86, CD80, CD40, CD163 and TLR4. Peripheral blood mononuclear cells (PBMCs) (10 HC, 11 hALF) were stimulated with LPS. Mφ intracellular TNFα, IL6 and IL10 were measured by FCM. CD14<sup>hi</sup>/CD16<sup>-</sup>and CD14<sup>hi</sup>/CD16<sup>+</sup>Mφ from 4 patients with paracetamol-hALF and 3 HC were sorted by FCM and the extracted RNA used for transcriptome analysis (Affymetrix ST1 GeneChip®). We used Qlucore omics explorer package for initial gene identification and MetaCore<sup>TM</sup>for molecular pathway analysis. <h3>Results</h3> A higher% of CD14<sup>hi</sup>/CD16<sup>+</sup>and lower% of CD14<sup>lo</sup>/CD16<sup>+</sup>Mφ were seen in hALF compared to HC (6.7% vs 4% and 1.2% vs 6.1%, p &lt; 0.01). Both CD14<sup>hi</sup>Mφ subsets expressed lower surface levels of HLA-DR, HLA-DQ and CD86 (p &lt; 0.001) but CD40 was unchanged and CD80 higher in hALF compared to HC (p &lt; 0.001). Mφ TLR4 expression was similar in hALF and HC. Although CD14<sup>hi</sup>/CD16<sup>-</sup>Mφ CD163 was similar, CD14<sup>hi</sup>/CD16<sup>+</sup>CD163 was higher in hALF than in HC (p &lt; 0.001). CD14<sup>hi</sup>/CD16<sup>+</sup>Mφ in patients who died or required transplantation had lower CD86 and higher CD163 than those who survived with medical management alone (p &lt; 0.05). In response to LPS the 2 CD14<sup>hi</sup>subsets were the predominant producers of cytokines. Compared to HC, only intracellular TNFα was lower in hALF CD14<sup>hi</sup>Mφ (p &lt; 0.01) whilst IL6 tended to be so (p &lt; 0.1) with no differences in IL10. TNFα production in CD14<sup>hi</sup>Mφ correlated with HLA-DR, HLA-DQ, CD86 and TLR4 expression (p &lt; 0.01). Enrichment networks statistics identified reduced gene expression for MHC II processing (CIITA, HLA-DM, HLA-DP, HLA-DQ) and non-canonical NFκB signalling (NIK, NFκB2). <h3>Conclusion</h3> Circulating CD14<sup>hi</sup>Mφ in hALF display phenotypic and functional similarities with anti-inflammatory, resolution-like macrophages that may be due to down-regulated non-canonical NFκB pathways. These 9pre-primed9 Mφ may be beneficial in the resolution of liver injury in hALF but leave the patient dangerously susceptible to further infections. <h3>Disclosure of interest</h3> None Declared.