Surgeons' assessment versus risk models for predicting complications of hepato-pancreato-biliary surgery (HPB-RISC): a multicenter prospective cohort study.

BACKGROUND: Several studies advise the use of risk models when counseling patients for hepato-pancreato-biliary (HPB) surgery, but studies comparing these models to the surgeons' assessment are lacking. The aim of this study was to assess whether risk prediction models outperform surgeons' assessment for the risk of complications in HPB surgery. METHODS: This prospective study included adult patients scheduled for HPB surgery in three centers in the UK and the Netherlands. Primary outcome was the rate of postoperative major complications. Surgeons assessed the risk prior to surgery while blinded for the formal risk scores. Risk prediction models were retrieved via a systematic review and risk scores were calculated. For each model, discrimination and calibration were evaluated. RESULTS: Overall, 349 patients were included. The rate of major complications was 27% and in-hospital mortality 3%. Surgeons' assessment resulted in an AUC of 0.64; 0.71 for liver and 0.56 for pancreas surgery (P = 0.020). The AUCs for nine existing risk prediction models ranged between 0.57 and 0.73 for liver surgery and between 0.51 and 0.57 for pancreas surgery. CONCLUSION: In HPB surgery, existing risk prediction models do not outperform surgeons' assessment. Surgeons' assessment outperforms most risk prediction models for liver surgery although both have a poor predictive performance for pancreas surgery. REGISTRATION INFORMATION: REC reference number (13/SC/0135); IRAS ID (119370). TRIALREGISTER.NL: NTR4649.

Natural killer cell maturation markers in the human liver and expansion of an NKG2C+KIR+ population.

BACKGROUND: Selected populations of murine natural killer (NK) cells possess memory features to haptens, cytokines, and viruses. Liver-specific adhesion molecules CXCR6 and CD49a have been identified as surface markers in mice. In people, expansion of long-lived terminally differentiated NKG2C+ populations occur in the blood after viral infection. We aimed to compare intrahepatic and blood NK cell receptor expression to determine the existence of CD49a+ and CXCR6+ NK cells in human liver and define the maturation status of NKG2C+ NK cells at this site. METHODS: Tissue samples were taken from the liver margin of 39 patients with hepatic metastases and flushed with chelating buffer followed by collagenase or mechanical digestion. Paired peripheral blood samples were taken from 15 patients, the remainder being unpaired. Mononuclear cells were isolated by ficoll separation and cell surface staining performed for CD3, CD56, CD16, CD57, CD117, CD161, CD158a, CD158b, CD49a, CD49b, CXCR6, NKG2C, and NKp46. Statistical analysis to compare intrahepatic and blood NK cell receptor expression included the median, IQR, and Mann-Whitney U test. FINDINGS: Frequencies of NK cell precursors were similar in the liver and the blood (0·91% [0·62-3·26] vs 0·87 [0·41-1·52]); however, expression of all later markers of maturity were reduced including CD16 (47% [40·4-61·4] vs 88·7 [82·2-93·2], p<0·0001), CD57 (30·7% [25·0-53·9] vs 73·4 [70·4-87·6], p=0·0003), and KIR (11·2% [7·5-14·5] vs 26·7 [17·3-30·8], p<0·0001). Expanded hepatic CD16- NK cells were particularly immature with reduced CD57 and increased CD161 compared with the blood. NKG2C+ NK cells were found in similar frequencies in liver and blood. The hepatic NKG2C+ population was terminally differentiated, as in the circulation, but demonstrated a three-fold increase in KIR expression compared with NKG2C- counterparts, which was not seen in the blood. As in previously published research in mice, CD49a+ and CXCR6+ NK cells were liver resident (6·5% [3·9-14·6] liver vs 2·1 [1·3-4·3] blood, p<0·0001, and 65·3 [48·1-75·2] vs 4·5 [1·43-12·12], p=0·0039, respectively). Both populations were immature, with reduced KIR expression. INTERPRETATION: We have shown that the liver contains an expanded population of immature CD16- NK cells. These cells might traffic from the blood and then differentiate into hepatic-specific CD49a+ and CXCR6+ NK cells. The function of these subsets is unknown but their immaturity hints against memory. Terminally differentiated NKG2C+ cells show KIR expansion in the human liver and probably represent an antigen-experienced population, raising the question of whether the liver is a site of NK cell memory acquisition. FUNDING: MRC Clinical Research Fellowship.

IL-12 and IL-15 induce the expression of CXCR6 and CD49a on peripheral natural killer cells.

INTRODUCTION: Murine hepatic NK cells exhibit adaptive features, with liver-specific adhesion molecules CXCR6 and CD49a acting as surface markers. METHODS: We investigated human liver-resident CXCR6+ and CD49a+ NK cells using RNA sequencing, flow cytometry, and functional analysis. We further assessed the role of cytokines in generating NK cells with these phenotypes from the peripheral blood. RESULTS: Hepatic CD49a+ NK cells could be induced using cytokines and produce high quantities of IFNγ and TNFα, in contrast to hepatic CXCR6+ NK cells. RNA sequencing of liver-resident CXCR6+ NK cells confirmed a tolerant immature phenotype with reduced expression of markers associated with maturity and cytotoxicity. Liver-resident double-positive CXCR6 + CD49a+ hepatic NK cells are immature but maintain high expression of Th1 cytokines as observed for single-positive CD49a+ NK cells. We show that stimulation with activating cytokines can readily induce upregulation of both CD49a and CXCR6 on NK cells in the peripheral blood. In particular, IL-12 and IL-15 can generate CXCR6 + CD49a+ NK cells in vitro from NK cells isolated from the peripheral blood, with comparable phenotypic and functional features to liver-resident CD49a+ NK cells, including enhanced IFNγ and NKG2C expression. CONCLUSION: IL-12 and IL-15 may be key for generating NK cells with a tissue-homing phenotype and strong Th1 cytokine profile in the blood, and links peripheral activation of NK cells with tissue-homing. These findings may have important therapeutic implications for immunotherapy of chronic liver disease.