Transplantation of high fat fed mouse microbiota into zebrafish larvae identifies MyD88-dependent acceleration of hyperlipidaemia by Gram-positive cell wall components.

Gut dysbiosis is an important modifier of pathologies including cardiovascular disease but our understanding of the role of individual microbes is limited. Here, we have used transplantation of mouse microbiota into microbiota-deficient zebrafish larvae to study the interaction between members of a mammalian high fat diet-associated gut microbiota with a lipid rich diet challenge in a tractable model species. We find zebrafish larvae are more susceptible to hyperlipidaemia when exposed to the mouse high fat-diet-associated microbiota and that this effect can be driven by two individual bacterial species fractionated from the mouse high fat-diet-associated microbiota. We find Stenotrophomonas maltophilia increases the hyperlipidaemic potential of chicken egg yolk to zebrafish larvae independent of direct interaction between S. maltophilia and the zebrafish host. Colonization by live, or exposure to heat-killed, Enterococcus faecalis accelerates hyperlipidaemia via host MyD88 signaling. The hyperlipidaemic effect is replicated by exposure to the Gram-positive toll-like receptor agonists peptidoglycan and lipoteichoic acid in a MyD88-dependent manner. In this work, we demonstrate the applicability of zebrafish as a tractable host for the identification of gut microbes that can induce conditional host phenotypes via microbiota transplantation and subsequent challenge with a high fat diet.

Outcomes for children after second liver transplantations are similar to those after first transplantations: a binational registry analysis.

OBJECTIVE: To assess long term graft and patient survival after donor liver retransplantation in children in Australia and New Zealand during 1986-2017; to determine the factors that influence survival. DESIGN: Retrospective cohort analysis (registry data). SETTING, PARTICIPANTS: Australia and New Zealand Liver Transplant Registry data for all liver retransplantations in children (under 18 years of age), 1986-2017, in all four paediatric and six adult liver transplantation centres in the two countries. MAIN OUTCOME MEASURES: Graft and patient survival at one, 5, 10 and 15 years. RESULTS: 142 liver retransplantations were undertaken in children (59 during 1986-2000, 83 during 2001-2017). Kaplan-Meier survival analysis indicated that survival was significantly greater during 2001-2017 than 1986-2000 (P < 0.001). During 2001-2017, graft survival one year after retransplantation was 84%, at 5 years 75%, at 10 years 70%, and at 15 years 54%; patient survival was 89% at one year, 87% at 5 years, 87% at 10 years, and 71% at 15 years. Median time between transplantations was 0.2 years (IQR, 0.03-1.4 years) during 1986-2000, and 1.8 years (IQR, 0.1-6.8 years) during 2001-2017 (P = 0.002). The proportion of graft failures that involved split grafts was larger during 2001-2017 (35 of 83, 42%) than 1986-2000 (10 of 59, 17%). Graft type, cause of graft failure, and number of transplants did not influence survival following retransplantation. CONCLUSION: Survival for children following retransplantation is excellent. Graft survival is similar for split and whole grafts. Children on the liver waiting list requiring retransplantation should have the same access to donor grafts as children requiring a first transplant.

Longitudinal immunosuppression data can minimize misclassification bias in solid organ transplantation cohorts.

BACKGROUND: Most cohort studies investigating the effect of immunosuppression on transplant outcomes use drugs at first hospital discharge. We evaluated the extent of drug exposure misclassification and its impact on outcome prediction. METHODS: We retrospectively collected longitudinal immunosuppression data, at discharge and at 1, 5, 10, and 15 years after transplantation, and outcomes for solid organ transplant recipients 1984-2006 (n = 3133). We compared the risk of death from exposure to individual immunosuppressive drugs (cyclosporine, tacrolimus, azathioprine, and mycophenolate) and dual therapies, as defined by discharge only vs longitudinal immunosuppression data, using adjusted Cox proportional hazards models. RESULTS: During a median follow-up of 5.2 years, immunosuppressive drugs were altered for 947 (30%) recipients and 955 recipients died. Longitudinal receipt of cyclosporine and azathioprine were associated with an increased risk (HR 1.41, 95% CI 1.07-1.89, and HR 1.34, 95% CI 1.00-1.80), and mycophenolate with a reduced risk (HR 0.35, 0.16-0.78), of death. Recipients on mycophenolate and tacrolimus dual therapy had a lower risk of death compared to those on azathioprine and cyclosporine dual therapy (HR 0.30, 0.10-0.93). The increased risk of death associated with the receipt of cyclosporine or azathioprine was not shown in the analyses based on drugs allocated at discharge, and all of the associations between immunosuppressive regimens and death were strengthened in the analyses based on longitudinal immunosuppression data. CONCLUSIONS: Cohort findings based on immunosuppressive drugs allocated at discharge should be interpreted with caution due to potential exposure misclassification. The use of granular, longitudinal data on immunosuppressive regimens could improve prediction.

miR-181a mediates TGF-ß-induced hepatocyte EMT and is dysregulated in cirrhosis and hepatocellular cancer.

BACKGROUND & AIMS: Epithelial-mesenchymal transition (EMT) has been implicated in the processes of embryogenesis, tissue fibrosis and carcinogenesis. Transforming growth factor-ß (TGF-ß) has been identified as a key driver of EMT and plays a key role in the pathogenesis of cirrhosis and hepatocellular carcinoma (HCC). The aim was to identify microRNA (miR) expression in TGF-ß-induced hepatocyte EMT. METHODS: We treated a human hepatocyte cell line PH5CH8 with TGF-ß to induce an EMT-like change in phenotype and then identified dysregulated miRs using TaqMan Low Density Arrays. MiR expression was altered using miR-181a mimic and inhibitor in the same system and gene changes were identified using TaqMan gene arrays. MiR-181a gene expression was measured in human and mouse cirrhotic or HCC liver tissue samples. Gene changes were identified in rAAV-miR-181a-expressing mouse livers using TaqMan gene arrays. RESULTS: We identified miR-181a as a miR that was significantly up-regulated in response to TGF-ß treatment. Over-expression of a miR-181a mimic induced an in vitro EMT-like change with a phenotype similar to that seen with TGF-ß treatment alone and was reversed using a miR-181a inhibitor. MiR-181a was shown to be up-regulated in experimental and human cirrhotic and HCC tissue. Mouse livers expressing rAAV-miR-181a showed genetic changes associated with TGF-ß signalling and EMT. CONCLUSIONS: MiR-181a had a direct effect in inducing hepatocyte EMT and was able to replace TGF-ß-induced effects in vitro. MiR-181a was over-expressed in cirrhosis and HCC and is likely to play a role in disease pathogenesis.

Grade of deceased donor liver macrovesicular steatosis impacts graft and recipient outcomes more than the Donor Risk Index.

BACKGROUND AND AIM: Donor liver steatosis can impact on liver allograft outcomes. The aim of the present study was to comprehensively report on the impact of type and grade of donor steatosis, as well as donor and recipient factors, including the reported Donor Risk Index (DRI), on liver allograft outcomes. METHODS: A review of unit data for all adult liver transplant procedures from 2001 to 2007, as well as donor offers. Donor liver biopsies were regraded for steatosis by an experienced histopathologist. RESULTS: Steatosis was detected in 184/255 (72%) of biopsies, of which 114 (62%) had microvesicular steatosis (MiS; 68 mild, 22 moderate, 24 severe) and 70 (38%) macrovesicular steatosis (MaS; 59 mild, 7 moderate, 4 severe). The majority (66/70, 94%) of biopsies with MaS also contained MiS. Allograft steatosis was associated with increasing donor body mass index (P = 0.000), plus donor male sex (P < 0.05). Primary non function (P = 0.002), early renal failure (P = 0.040), and requirement for retransplantation (P = 0.012) were associated only with severe MaS. Early biliary complications were associated with moderate MaS (P = 0.039). Only severe MaS was significantly associated with inferior allograft survival at 3 months (relative risk = 12.09 [8.75-19.05], P = 0.000) and 1 year (P = 0.000). CONCLUSIONS: MiS is a common finding and frequently coexists with MaS on liver allograft biopsy, while isolated MaS is uncommon. Only the presence of moderate to severe MaS is associated with inferior early allograft outcomes. The impact of severe MaS on allograft survival appears greater than other donor factors, including the calculated DRI.

Cadaveric liver transplant from older donors.

OBJECTIVE: To examine the effects of cadaveric donor age on outcomes following orthotopic liver transplantation OLT. METHODS: Data were collected on all patients who underwent OLT between January 1997 and December 2004 at the Royal Prince Alfred Hospital, Sydney, New South Wales, Australia. During this period, 313 OLTs were performed: 51 patients 16% received older donor livers OD; 60 or more years old, and 262 84% received younger donor livers YD; less than 60 years old. RESULTS: In the study group 313 patients, we found significantly more recipients of OD liver with blood group O: 51% versus 33% p=0.025 and with fulminant hepatic failure: 9.8% versus 5% p=0.018 compared to YD recipients. No difference between OD and YD liver recipients was found in initial poor graft function: 16/51 31% versus 74/262 28%, primary non-functioning: 6.5% versus 6.5%, the overall graft loss: 15/51 29% versus 62/262 24%, post-revascularization liver biopsy steatosis: 14/40 35% versus 82/232 36% or hepatic artery thrombosis: 1/51 2% versus 8/262 3%. There was no difference in graft actuarial survival between OD and YD recipients at 1, 3, and 5 years, 82% versus 87%, 75% versus 81%, and 75% versus 77% p=0.27 log rank or patient actuarial survival, 86% versus 89%, 79% versus 83%, and 79% versus 80% p=0.336 log rank. CONCLUSION: Orthotopic liver transplantation can be achieved with acceptable outcomes using selected livers from older deceased donors.

Autonomic and peripheral neuropathy in endstage liver disease and following liver transplantation.

Severe chronic liver disease may be associated with a peripheral somatic and an autonomic neuropathy. There are only a limited number of reports on the incidence and features of these neuropathies. In addition the effects of liver transplantation on these neuropathies have not been well studied. We examined peripheral somatic and autonomic nerve function in 42 patients with endstage liver disease prior to transplantation and also examined the effect of liver transplantation on these neuropathies in 14 patients. Peripheral somatic neuropathy (93%) and autonomic neuropathy (50%) were common in patients with endstage liver disease and were more frequent than previously reported. Abnormalities improved in some patients after liver transplantation, particularly if there was return of normal hepatic function.

Passive transfer of nut allergy after liver transplantation.

An anaphylactic reaction to cashew nut developed in a nonatopic 60-year-old man 25 days after receiving a liver allograft from a 15-year-old atopic boy who died of anaphylaxis after peanut ingestion. The liver recipient had no history of nut allergy. Posttransplantation skin prick test results were positive for peanut, cashew nut, and sesame seed, and the donor had allergen-specific IgE antibodies to the same 3 allergens. Contact tracing of the recipients of other solid organs from the same donor disclosed no other development of allergic symptoms after ingestion of peanut or cashew nut. Results of molecular HLA typing did not detect any donor-origin leukocytes in the recipient after transplantation, which excluded peripheral microchimerism. The patient inadvertently ingested peanut-contaminated food and suffered a second anaphylactic reaction 32 weeks after the transplantation. This case illustrates that transfer of IgE-mediated hypersensitivity can occur after liver transplantation and have potentially serious consequences. We therefore recommend that organ donors undergo screening for allergies, and that recipients be advised regarding allergen avoidance.