Acute kidney injury and post-reperfusion syndrome in liver transplantation

In the past decades liver transplantation (LT) has become the treatment of choice for patients with end stage liver disease (ESLD). The chronic shortage of cadaveric organs for transplantation led to the utilization of a greater number of marginal donors such as older donors or donors after circulatory death (DCD). The improved survival of transplanted patients has increased the frequency of long-term complications, in particular chronic kidney disease (CKD). Acute kidney injury (AKI) post-LT has been recently recognized as an important risk factor for the occurrence of de novo CKD in the long-term outcome. The onset of AKI post-LT is multifactorial, with pre-LT risk factors involved, including higher Model for End-stage Liver Disease score, more sever ESLD and pre-existing renal dysfunction, either with intra-operative conditions, in particular ischaemia reperfusion injury responsible for post-reperfusion syndrome (PRS) that can influence recipient’s morbidity and mortality. Post-reperfusion syndrome-induced AKI is an important complication post-LT that characterizes kidney involvement caused by PRS with mechanisms not clearly understood and implication on graft and patient survival. Since pre-LT risk factors may influence intra-operative events responsible for PRS-induced AKI, we aim to consider all the relevant aspects involved in PRS-induced AKI in the setting of LT and to identify all studies that better clarified the specific mechanisms linking PRS and AKI. A PubMed search was conducted using the terms liver transplantation AND acute kidney injury; liver transplantation AND post-reperfusion syndrome; acute kidney injury AND post-reperfusion syndrome; acute kidney injury AND DCD AND liver transplantation. Five hundred seventy four articles were retrieved on PubMed search. Results were limited to title/abstract of English-language articles published between 2000 and 2015. Twenty-three studies were identified that specifically evaluated incidence, risk factors and outcome for patients developing PRS-induced AKI in liver transplantation. In order to identify intra-operative risk factors/mechanisms specifically involved in PRS-induced AKI, avoiding confounding factors, we have limited our study to “acute kidney injury AND DCD AND liver transplantation”. Accordingly, three out of five studies were selected for our purpose

Portal hypertension in polycystic liver disease patients does not affect wait-list or immediate post-liver transplantation outcomes

AIM: To establish the impact of portal hypertension (PH) on wait-list/post-transplant outcomes in patients with polycystic liver disease (PCLD) listed for liver transplantation. METHODS: A retrospective single-centre case controlled study of consecutive patients listed for liver transplantation over 12 years was performed from our centre. PH in the PCLD cohort was defined by the one or more of following parameters: (1) presence of radiological or endoscopic documented varices from our own centre or the referral centre; (2) splenomegaly (> 11 cm) on radiology in absence of splenic cysts accounting for increased imaging size; (3) thrombocytopenia (platelets < 150 × 10(9)/L); or (4) ascites without radiological evidence of hepatic venous outflow obstruction from a single cyst. RESULTS: Forty-seven PCLD patients (F: M = 42: 5) were listed for liver transplantation (LT) (single organ, n = 35; combined liver-kidney transplantation, n = 12) with 19 patients (40.4%) having PH. When comparing the PH group with non-PH group, the mean listing age (PH group, 50.6 (6.4); non-PH group, 47.1 (7.4) years; P = 0.101), median listing MELD (PH group, 12; non-PH group, 11; P = 0.422) median listing UKELD score (PH group, 48; non-PH group, 46; P = 0.344) and need for renal replacement therapy (P = 0.317) were similar. In the patients who underwent LT alone, there was no difference in the duration of ICU stay (PH, 3 d; non-PH, 2 d; P = 0.188), hospital stay length (PH, 9 d; non-PH, 10 d; P = 0.973), or frequency of renal replacement therapy (PH, 2/8; non-PH, 1/14; P = 0.121) in the immediate post-transplantation period. CONCLUSION: Clinically apparent portal hypertension in patients with PCLD listed for liver transplantation does not appear to have a major impact on wait-list or peri-transplant morbidity

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist

SARS-CoV-2 Omicron is an immune escape variant with an altered cell entry pathway

Vaccines based on the spike protein of SARS-CoV-2 are a cornerstone of the public health response to COVID-19. The emergence of hypermutated, increasingly transmissible variants of concern (VOCs) threaten this strategy. Omicron (B.1.1.529), the fifth VOC to be described, harbours multiple amino acid mutations in spike, half of which lie within the receptor-binding domain. Here we demonstrate substantial evasion of neutralization by Omicron BA.1 and BA.2 variants in vitro using sera from individuals vaccinated with ChAdOx1, BNT162b2 and mRNA-1273. These data were mirrored by a substantial reduction in real-world vaccine effectiveness that was partially restored by booster vaccination. The Omicron variants BA.1 and BA.2 did not induce cell syncytia in vitro and favoured a TMPRSS2-independent endosomal entry pathway, these phenotypes mapping to distinct regions of the spike protein. Impaired cell fusion was determined by the receptor-binding domain, while endosomal entry mapped to the S2 domain. Such marked changes in antigenicity and replicative biology may underlie the rapid global spread and altered pathogenicity of the Omicron variant

Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study

Background: The SARS-CoV-2 delta (B.1.617.2) variant was first detected in England in March, 2021. It has since rapidly become the predominant lineage, owing to high transmissibility. It is suspected that the delta variant is associated with more severe disease than the previously dominant alpha (B.1.1.7) variant. We aimed to characterise the severity of the delta variant compared with the alpha variant by determining the relative risk of hospital attendance outcomes. Methods: This cohort study was done among all patients with COVID-19 in England between March 29 and May 23, 2021, who were identified as being infected with either the alpha or delta SARS-CoV-2 variant through whole-genome sequencing. Individual-level data on these patients were linked to routine health-care datasets on vaccination, emergency care attendance, hospital admission, and mortality (data from Public Health England's Second Generation Surveillance System and COVID-19-associated deaths dataset; the National Immunisation Management System; and NHS Digital Secondary Uses Services and Emergency Care Data Set). The risk for hospital admission and emergency care attendance were compared between patients with sequencing-confirmed delta and alpha variants for the whole cohort and by vaccination status subgroups. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar week, and vaccination status. Findings: Individual-level data on 43 338 COVID-19-positive patients (8682 with the delta variant, 34 656 with the alpha variant; median age 31 years [IQR 17–43]) were included in our analysis. 196 (2·3%) patients with the delta variant versus 764 (2·2%) patients with the alpha variant were admitted to hospital within 14 days after the specimen was taken (adjusted hazard ratio [HR] 2·26 [95% CI 1·32–3·89]). 498 (5·7%) patients with the delta variant versus 1448 (4·2%) patients with the alpha variant were admitted to hospital or attended emergency care within 14 days (adjusted HR 1·45 [1·08–1·95]). Most patients were unvaccinated (32 078 [74·0%] across both groups). The HRs for vaccinated patients with the delta variant versus the alpha variant (adjusted HR for hospital admission 1·94 [95% CI 0·47–8·05] and for hospital admission or emergency care attendance 1·58 [0·69–3·61]) were similar to the HRs for unvaccinated patients (2·32 [1·29–4·16] and 1·43 [1·04–1·97]; p=0·82 for both) but the precision for the vaccinated subgroup was low. Interpretation: This large national study found a higher hospital admission or emergency care attendance risk for patients with COVID-19 infected with the delta variant compared with the alpha variant. Results suggest that outbreaks of the delta variant in unvaccinated populations might lead to a greater burden on health-care services than the alpha variant. Funding: Medical Research Council; UK Research and Innovation; Department of Health and Social Care; and National Institute for Health Research

Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study

Background The SARS-CoV-2 variant B.1.1.7 was first identified in December, 2020, in England. We aimed to investigate whether increases in the proportion of infections with this variant are associated with differences in symptoms or disease course, reinfection rates, or transmissibility. Methods We did an ecological study to examine the association between the regional proportion of infections with the SARS-CoV-2 B.1.1.7 variant and reported symptoms, disease course, rates of reinfection, and transmissibility. Data on types and duration of symptoms were obtained from longitudinal reports from users of the COVID Symptom Study app who reported a positive test for COVID-19 between Sept 28 and Dec 27, 2020 (during which the prevalence of B.1.1.7 increased most notably in parts of the UK). From this dataset, we also estimated the frequency of possible reinfection, defined as the presence of two reported positive tests separated by more than 90 days with a period of reporting no symptoms for more than 7 days before the second positive test. The proportion of SARS-CoV-2 infections with the B.1.1.7 variant across the UK was estimated with use of genomic data from the COVID-19 Genomics UK Consortium and data from Public Health England on spike-gene target failure (a non-specific indicator of the B.1.1.7 variant) in community cases in England. We used linear regression to examine the association between reported symptoms and proportion of B.1.1.7. We assessed the Spearman correlation between the proportion of B.1.1.7 cases and number of reinfections over time, and between the number of positive tests and reinfections. We estimated incidence for B.1.1.7 and previous variants, and compared the effective reproduction number, Rt, for the two incidence estimates. Findings From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36 920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up. We found no changes in reported symptoms or disease duration associated with B.1.1.7. For the same period, possible reinfections were identified in 249 (0·7% [95% CI 0·6–0·8]) of 36 509 app users who reported a positive swab test before Oct 1, 2020, but there was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants. Reinfection occurrences were more positively correlated with the overall regional rise in cases (Spearman correlation 0·56–0·69 for South East, London, and East of England) than with the regional increase in the proportion of infections with the B.1.1.7 variant (Spearman correlation 0·38–0·56 in the same regions), suggesting B.1.1.7 does not substantially alter the risk of reinfection. We found a multiplicative increase in the Rt of B.1.1.7 by a factor of 1·35 (95% CI 1·02–1·69) relative to pre-existing variants. However, Rt fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant. Interpretation The lack of change in symptoms identified in this study indicates that existing testing and surveillance infrastructure do not need to change specifically for the B.1.1.7 variant. In addition, given that there was no apparent increase in the reinfection rate, vaccines are likely to remain effective against the B.1.1.7 variant. Funding Zoe Global, Department of Health (UK), Wellcome Trust, Engineering and Physical Sciences Research Council (UK), National Institute for Health Research (UK), Medical Research Council (UK), Alzheimer's Society

Genomic assessment of quarantine measures to prevent SARS-CoV-2 importation and transmission

Mitigation of SARS-CoV-2 transmission from international travel is a priority. We evaluated the effectiveness of travellers being required to quarantine for 14-days on return to England in Summer 2020. We identified 4,207 travel-related SARS-CoV-2 cases and their contacts, and identified 827 associated SARS-CoV-2 genomes. Overall, quarantine was associated with a lower rate of contacts, and the impact of quarantine was greatest in the 16–20 age-group. 186 SARS-CoV-2 genomes were sufficiently unique to identify travel-related clusters. Fewer genomically-linked cases were observed for index cases who returned from countries with quarantine requirement compared to countries with no quarantine requirement. This difference was explained by fewer importation events per identified genome for these cases, as opposed to fewer onward contacts per case. Overall, our study demonstrates that a 14-day quarantine period reduces, but does not completely eliminate, the onward transmission of imported cases, mainly by dissuading travel to countries with a quarantine requirement