STAT4-associated natural killer cell tolerance following liver transplantation.

OBJECTIVE: Natural killer (NK) cells are important mediators of liver inflammation in chronic liver disease. The aim of this study was to investigate why liver transplants (LTs) are not rejected by NK cells in the absence of human leukocyte antigen (HLA) matching, and to identify a tolerogenic NK cell phenotype. DESIGN: Phenotypic and functional analyses on NK cells from 54 LT recipients were performed, and comparisons made with healthy controls. Further investigation was performed using gene expression analysis and donor:recipient HLA typing. RESULTS: NK cells from non-HCV LT recipients were hypofunctional, with reduced expression of NKp46 (p<0.05) and NKp30 (p<0.001), reduced cytotoxicity (p<0.001) and interferon (IFN)-γ secretion (p<0.025). There was no segregation of this effect with HLA-C, and these functional changes were not observed in individuals with HCV. Microarray and RT-qPCR analysis demonstrated downregulation of STAT4 in NK cells from LT recipients (p<0.0001). Changes in the expression levels of the transcription factors Helios (p=0.06) and Hobit (p=0.07), which control NKp46 and IFNγ expression, respectively, were also detected. Hypofunctionality of NK cells was associated with impaired STAT4 phosphorylation and downregulation of the STAT4 target microRNA-155. Conversely in HCV-LT NK cell tolerance was reversed, consistent with the more aggressive outcome of LT for HCV. CONCLUSIONS: LT is associated with transcriptional and functional changes in NK cells, resulting in reduced activation. NK cell tolerance occurs upstream of major histocompatibility complex (MHC) class I mediated education, and is associated with deficient STAT4 phosphorylation. STAT4 therefore represents a potential therapeutic target to induce NK cell tolerance in liver disease.

Wireless capsule endoscopy in the investigation of intestinal Behçet's syndrome.

OBJECTIVE: Intestinal Behçet's Syndrome (BS) is a difficult diagnosis to establish. We describe the use of wireless capsule endoscopy (WCE) in the investigation of 11 patients with suspected intestinal BS. METHODS: Out of 11 patients, 10 with suspected intestinal BS were found to have small intestinal ulcers on capsule endoscopy. Each case was retrospectively assessed for symptoms, signs, anaemia, other investigations, treatment and complications. RESULTS: All 11 patients had established diagnoses of BS as defined by the International Study Group criteria. Central abdominal pain and change in bowel habit were the predominant symptoms, both occurring in seven patients. Upper gastrointestinal (GI) endoscopy and colonoscopy identified duodenitis, ileitis and colitis in three patients. Barium studies and CT were normal in all cases. WCE revealed small intestinal ulcers throughout the ileum in five patients and ulcers located either in the proximal and/or distal ileum in five other patients. One patient had significant symptoms, signs and ulcers leading to a change in treatment to infliximab, and this resulted in resolution of symptoms and ulcers. Ten age- and sex-matched controls investigated for unexplained GI symptoms had no intestinal lesions on capsule endoscopy. CONCLUSION: WCE is useful in the investigation of GI symptoms in BS. It is particularly helpful in those patients in whom conventional investigations have been normal or fail to account for symptoms and signs. This technique may guide treatment and provide a better understanding of intestinal pathology in BS.