An international genome-wide meta-analysis of primary biliary cholangitis: Novel risk loci and candidate drugs

BACKGROUNDS & AIMS

Primary biliary cholangitis (PBC) is a chronic liver disease in which autoimmune destruction of the small intrahepatic bile ducts eventually leads to cirrhosis. Many patients have inadequate response to licensed medications, motivating the search for novel therapies. Previous genome-wide association studies (GWAS) and meta-analyses (GWMA) of PBC have identified numerous risk loci for this condition, providing insight into its aetiology. We undertook the largest GWMA of PBC to date, aiming to identify additional risk loci and prioritise candidate genes for in silico drug efficacy screening.

METHODS

We combined new and existing genotype data for 10,516 cases and 20,772 controls from 5 European and 2 East Asian cohorts.

RESULTS

We identified 56 genome-wide significant loci (20 novel) including 46 in European, 13 in Asian, and 41 in combined cohorts; and a 57th genome-wide significant locus (also novel) in conditional analysis of the European cohorts. Candidate genes at newly identified loci include FCRL3, INAVA, PRDM1, IRF7, CCR6, CD226, and IL12RB1, which each play key roles in immunity. Pathway analysis reiterated the likely importance of pattern recognition receptor and TNF signalling, JAK-STAT signalling, and differentiation of T helper (TH)1 and TH17 cells in the pathogenesis of this disease. Drug efficacy screening identified several medications predicted to be therapeutic in PBC, some of which are well-established in the treatment of other autoimmune disorders.

CONCLUSIONS

This study has identified additional risk loci for PBC, provided a hierarchy of agents that could be trialled in this condition, and emphasised the value of genetic and genomic approaches to drug discovery in complex disorders.

LAY SUMMARY

Primary biliary cholangitis (PBC) is a chronic liver disease that eventually leads to cirrhosis. In this study, we analysed genetic information from 10,516 people with PBC and 20,772 healthy individuals recruited in Canada, China, Italy, Japan, the UK, or the USA. We identified several genetic regions associated with PBC. Each of these regions contains several genes. For each region, we used diverse sources of evidence to help us choose the gene most likely to be involved in causing PBC. We used these 'candidate genes' to help us identify medications that are currently used for treatment of other conditions, which might also be useful for treatment of PBC.

Effects of Primary Biliary Cholangitis on Quality of Life and Health Care Costs in the United Kingdom

BACKGROUND & AIMS

There have been few high-quality studies of the costs, preference-based health-related quality of life (HRQoL) and cost effectiveness of treatments for primary biliary cholangitis (PBC). We aimed to estimate the marginal effects of PBC complications and symptoms, accounting for treatment, on HRQoL and the annual cost of health care in the United Kingdom (UK). These are essential components for evaluation of cost effectiveness and this information will aid in evaluation of new treatments.

METHODS

Questionnaires were mailed to 4583 participants in the UK-PBC research cohort and data were collected on HRQoL and use of the National Health Service (NHS) in the UK from 2015 through 2016. HRQoL was measured using the EQ-5D-5L instrument. The annual cost of resource use was calculated using unit costs obtained from NHS sources. We performed econometric analyses to determine the effects of treatment, symptoms, complications, liver transplantation status, and patient characteristics on HRQoL and annual costs.

RESULTS

In an analysis of data from 2240 participants (over 10% of all UK PBC patients), we found that PBC symptoms have a considerable effect on HRQoL. Ursodeoxycholic acid therapy was associated with significantly higher HRQoL regardless of response status. Having had a liver transplant and ascites were also independently associated with reduced HRQoL. Having had a liver transplant (US$4294) and esophageal varices (US$3401) were the factors with the two greatest mean annual costs to the NHS. Symptoms were not independently associated with cost but were associated with reduction in HRQoL for patients, indicating the lack of effective treatments for PBC symptoms.

CONCLUSIONS

In an analysis of data from 2240 participants in the UK PBC, we found that HRQoL and cost estimates provide greater insight into the relative importance of PBC-related symptoms and complications. These findings provide estimates for health technology assessments of new treatments for PBC.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Pretreatment prediction of response to ursodeoxycholic acid in primary biliary cholangitis: development and validation of the UDCA Response Score

BACKGROUND

Treatment guidelines recommend a stepwise approach to primary biliary cholangitis: all patients begin treatment with ursodeoxycholic acid (UDCA) monotherapy and those with an inadequate biochemical response after 12 months are subsequently considered for second-line therapies. However, as a result, patients at the highest risk can wait the longest for effective treatment. We determined whether UDCA response can be accurately predicted using pretreatment clinical parameters.

METHODS

We did logistic regression analysis of pretreatment variables in a discovery cohort of patients in the UK with primary biliary cholangitis to derive the best-fitting model of UDCA response, defined as alkaline phosphatase less than 1·67 times the upper limit of normal (ULN), measured after 12 months of treatment with UDCA. We validated the model in an external cohort of patients with primary biliary cholangitis and treated with UDCA in Italy. Additionally, we assessed correlations between model predictions and key histological features, such as biliary injury and fibrosis, on liver biopsy samples.

FINDINGS

2703 participants diagnosed with primary biliary cholangitis between Jan 1, 1998, and May 31, 2015, were included in the UK-PBC cohort for derivation of the model. The following pretreatment parameters were associated with lower probability of UDCA response: higher alkaline phosphatase concentration (p<0·0001), higher total bilirubin concentration (p=0·0003), lower aminotransferase concentration (p=0·0012), younger age (p<0·0001), longer interval from diagnosis to the start of UDCA treatment (treatment time lag, p<0·0001), and worsening of alkaline phosphatase concentration from diagnosis (p<0·0001). Based on these variables, we derived a predictive score of UDCA response. In the external validation cohort, 460 patients diagnosed with primary biliary cholangitis were treated with UDCA, with follow-up data until May 31, 2016. In this validation cohort, the area under the receiver operating characteristic curve for the score was 0·83 (95% CI 0·79-0·87). In 20 liver biopsy samples from patients with primary biliary cholangitis, the UDCA response score was associated with ductular reaction (r=-0·556, p=0·0130) and intermediate hepatocytes (probability of response was 0·90 if intermediate hepatocytes were absent vs 0·51 if present).

INTERPRETATION

We have derived and externally validated a model based on pretreatment variables that accurately predicts UDCA response. Association with histological features provides face validity. This model provides a basis to explore alternative approaches to treatment stratification in patients with primary biliary cholangitis.

FUNDING

UK Medical Research Council and University of Milan-Bicocca.

Tissue distribution of products of the mouse decay-accelerating factor (DAF) genes. Exploitation of a Daf1 knock-out mouse and site-specific monoclonal antibodies

Decay-accelerating factor (DAF) is a membrane regulator of C3 activation that protects self cells from autologous complement attack. In humans, DAF is uniformly expressed as a glycosylphosphatidylinositol (GPI)-anchored molecule. In mice, both GPI-anchored and transmembrane-anchored DAF proteins are produced, each of which can be derived from two different genes (Daf1 and Daf2). In this report, we describe a Daf1 gene knock-out mouse arising as the first product of a strategy for targeting one or both Daf genes. As part of the work, we characterize recently described monoclonal antibodies against murine DAF protein using deletion mutants synthesized in yeast, and then employ the monoclonal antibodies in conjunction with wild-type and the Daf1 knock-out mice to determine the tissue distribution of the mouse Daf1 and Daf2 gene products. To enhance the immunohistochemical detection of murine DAF protein, we utilized the sensitive tyramide fluorescence method. In wild-type mice, we found strong DAF labelling of glomeruli, airway and gut epithelium, the spleen, vascular endothelium throughout all tissues, and seminiferous tubules of the testis. In Daf1 knock-out mice, DAF labelling was ablated in most tissues, but strong labelling of the testis and splenic dendritic cells remained. In both sites, reverse transcription-polymerase chain reaction analyses identified both GPI and transmembrane forms of Daf2 gene-derived protein. The results have relevance for studies of in vivo murine DAF function and of murine DAF structure.

A feasibility study of chiropractic spinal manipulation versus sham spinal manipulation for chronic otitis media with effusion in children

BACKGROUND

Pediatric otitis media with effusion is a common and costly condition. Although chiropractors have anecdotally claimed success in treating otitis media, there is little research to support their claims.

OBJECTIVE

A pilot study was undertaken for the purpose of assessing the feasibility of conducting a full-scale randomized clinical trial investigating the efficacy of chiropractic spinal manipulative therapy (SMT) for children with chronic otitis media with effusion.

METHODS

This study was a prospective, parallel-group, observer-blinded, randomized feasibility study. Twenty-two patients, ages 6 months to 6 years, received either active chiropractic SMT or placebo chiropractic SMT. Otoscopy and tympanometry were used to create a middle ear status profile, and daily diaries were collected.

RESULTS

Five newspaper advertisements over 6 months generated 105 responses. Twenty patients subsequently qualified and were randomized into the study. Collection of tympanometric and otoscopic data proved to be challenging. Compliance with the treatment and evaluation protocols and daily diaries was excellent. There were no reports of serious side effects as a result of either the active or placebo chiropractic treatments.

CONCLUSION

Recruitment for a randomized controlled trial is feasible and could be enhanced by medical collaboration. Patients and parents are able and willing to participate in a study comparing active SMT and placebo SMT. Parents were extremely compliant with the daily diaries, suggesting that similar quality-of-life and functional status measures can be successfully used in a larger trial. We found the objective outcomes assessment involving tympanometry and otoscopy extremely challenging and should be performed by experienced examiners in future studies.

Use of Gen-Probe and Bactec for rapid isolation and identification of mycobacteria. Correlation of probe results with growth index

Gen-Probe culture confirmation tests (Gen-Probe, San Diego, CA) for Mycobacterium tuberculosis complex and Mycobacterium avium complex were performed on 276 mycobacterial isolates. All 138 M. tuberculosis complex isolates and 79 of 80 M. avium complex isolates were identified correctly. No falsely positive test results were obtained; 58 nontuberculous mycobacteria other than M. avium complex were negative by Gen-Probe. In a second phase of testing, Gen-Probe tests were performed using concentrates from 101 patient Bactec 12B cultures. Positive results by Gen-Probe tests were correlated with the growth index (GI) reading on the day of processing as well as the accumulated GI readings. For those 51 with high (greater than or equal to 999) final GIs, 40/40 (100%) M. tuberculosis complex isolates and 9/11 M. avium complex isolates were positive by Gen-Probe, and six other mycobacteria were negative. Of the 25 with moderate final readings (400 less than or equal to GI less than 999), 12/17 M. tuberculosis complex isolates and 1/1 M. avium complex isolates were correctly identified by Gen-Probe; seven other mycobacteria were negative. Of 25 with low readings (GI less than 400), 8/24 M. tuberculosis isolates were correctly identified by Gen-Probe, and no falsely positive test results were obtained with the other probes. All true negative tests on seven other mycobacteria (not M. tuberculosis complex or M. avium complex) had less than 2% hybridization. Of the 24 falsely negative tests on M. tuberculosis complex isolates or M. avium complex isolates, 22 had greater than 2% hybridization with their respective probes. Thus, percent hybridization greater than 2% may be a useful indicator of the need for retesting.

Comparison of two prophylactic single-dose intravenous antibiotic regimes in the treatment of patients undergoing elective colorectal surgery in a district general hospital

Two hundred and twenty-nine patients were entered into a study to compare the effectiveness and safety of two single-shot antibiotic regimes in patients undergoing elective colorectal surgery in two district general hospitals. A single shot of intravenous (IV) latamoxef disodium was as effective as an IV combination of cefuroxime and metronidazole in control of wound infection following elective large bowel surgery when given as a bolus at the time of anaesthetic induction. The incidence of major wound infection was 6% and was evenly distributed in the two treatment groups. Half the major wound infections were associated with faecal fistulae. A single shot of IV antibiotic at the time of anaesthetic induction was safe, simple and an effective prophylaxis against major wound infection. There was a low incidence (1.3%) of serious postoperative bleeding and no serious adverse reactions were noted. The overall mortality was 9%. Death was significantly related to elderly patients, a poor performance status, operative contamination and wound infections.

Immunoidentification of Histoplasma capsulatum and Blastomyces dermatitidis with commercial exoantigen reagents. Effect of culture age

We have studied the effect of the length of incubation on the reliability of commercial exoantigen test reagents (Nolan/Scott Biological Laboratories Inc, and Immuno-Mycologics Inc). Antigen extracts, tested in each commercial system, were prepared from duplicate sets of cultures of Histoplasma capsulatum (12 isolates) and of Blastomyces dermatitidis (11 isolates) after one to six weeks of growth. For isolates of H capsulatum, antigens necessary for immunoidentification were detected in most cultures in two weeks and in all cultures after four weeks of incubation for both Nolan and Immuno-Mycologics reagents, and continued to be detected for at least six weeks. Positive results could usually be obtained from exoantigen tests for H capsulatum before dimorphism could be demonstrated by conversion of the mold to yeast. Diagnostically significant antigen was not uniformly present in all cultures of B dermatitidis during the test period, but ten of 11 isolates were positive at some time during the six weeks using the Nolan reagents; antigen of only one of 11 isolates was detected by the Immuno-Mycologic reagents. Results of exoantigen tests for B dermatitidis were usually not available until after the identity had been confirmed by conversion of the mold to yeast phase on cottonseed agar.

Contributions of processing preservation towards the food technologies of the 1980s

Food technology of the 1980s will encompass two distinct approaches, the evolutionary and the revolutionary path. Every existing technology needs constant updating to improve the economy of the process, incorporate further nutritional safeguards and pay respect to changes in flavour and texture dictated by customers’ demand. Fundamentally, food technology serves to bridge the gap between harvesting and consumption of foods, but it has progressed over centuries from improving palatability and enhancing nutritive values of foods to the creation of entirely new food items. Novel marketing methods have, particularly in the last 2-3 decades, highlighted the need for prolonged yet safe shelf life of fresh foods, bringing into the forefront the study of chemical and biochemical changes in foods and the study of means to arrest or reduce them. Sun-drying foods to minimize biological activity - an ancient art - has branched into a considerable variety of processes, still open to further sophistication. Freezing and heat - pasteurization and sterilization - will not only embrace new instrumentation but new forms of packaging. We shall see the surface coating of foods, and the displacement of air by inert gas, in wrapped foods playing an ever increasing part in the prevention of spoilage and deterioration.