Nanoparticle-based strategies in alcoholic liver disease and hepatocellular carcinoma: therapeutic and diagnostic perspectives

Diabetes, Liver Cancer, and Cirrhosis: What Next?

Davila JA, Morgan RO, Shaib Y, McGlynn KA, El-Serag HB (Houston Veterans Affairs Medical Center, Houston, Texas). Diabetes increases the risk of hepatocellular carcinoma in the United States: a population based case control study. Gut 2005;54:533–539.

Epidemiology of hepatocellular carcinoma in the United States: where are we? Where do we go?

Alcoholic liver damage–toxicity, autoimmunity and allergy

Article Figures and data Abstract Editor's evaluation eLife digest Introduction Materials and methods Results Discussion Data availability References Decision letter Author response Article and author information Metrics Abstract Background: Whether the positive associations of smoking and alcohol consumption with gastrointestinal diseases are causal is uncertain. We conducted this Mendelian randomization (MR) to comprehensively examine associations of smoking and alcohol consumption with common gastrointestinal diseases. Methods: Genetic variants associated with smoking initiation and alcohol consumption at the genome-wide significance level were selected as instrumental variables. Genetic associations with 24 gastrointestinal diseases were obtained from the UK Biobank, FinnGen study, and other large consortia. Univariable and multivariable MR analyses were conducted to estimate the overall and independent MR associations after mutual adjustment for genetic liability to smoking and alcohol consumption. Results: Genetic predisposition to smoking initiation was associated with increased risk of 20 of 24 gastrointestinal diseases, including 7 upper gastrointestinal diseases (gastroesophageal reflux, esophageal cancer, gastric ulcer, duodenal ulcer, acute gastritis, chronic gastritis, and gastric cancer), 4 lower gastrointestinal diseases (irritable bowel syndrome, diverticular disease, Crohn’s disease, and ulcerative colitis), 8 hepatobiliary and pancreatic diseases (non-alcoholic fatty liver disease, alcoholic liver disease, cirrhosis, liver cancer, cholecystitis, cholelithiasis, and acute and chronic pancreatitis), and acute appendicitis. Fifteen out of 20 associations persisted after adjusting for genetically predicted alcohol consumption. Genetically predicted higher alcohol consumption was associated with increased risk of duodenal ulcer, alcoholic liver disease, cirrhosis, and chronic pancreatitis; however, the association for duodenal ulcer did not remain statistically significant after adjustment for genetic predisposition to smoking initiation. Conclusions: This study provides MR evidence supporting causal associations of smoking with a broad range of gastrointestinal diseases, whereas alcohol consumption was associated with only a few gastrointestinal diseases. Funding: The Natural Science Fund for Distinguished Young Scholars of Zhejiang Province; National Natural Science Foundation of China; Key Project of Research and Development Plan of Hunan Province; the Swedish Heart Lung Foundation; the Swedish Research Council; the Swedish Cancer Society. Editor's evaluation This is a valuable article that is methodologically convincing and provides evidence, through Mendelian Randomisation, that genetic predisposition to smoking and alcohol consumption influences the risk to develop different gastrointestinal diseases. The findings largely corroborate the findings from observational studies, especially for the effects of smoking. The major strength of the paper is the use of the largest possible genetic datasets for both the exposures and outcomes, which makes the findings more robust. https://doi.org/10.7554/eLife.84051.sa0 Decision letter eLife's review process eLife digest People who smoke cigarettes or drink large amounts of alcohol are more likely to develop disorders with their digestive system. But it is difficult to prove that heavy drinking or smoking is the primary cause of these gastrointestinal diseases. For example, it is possible that having a digestive disorder makes people more likely to take up these habits to reduce pain or discomfort caused by the illness (an effect known as reverse causation). The association may also be the result of confounding factors, such as age or diet, which contribute to digestive problems as well as the health outcomes of smoking and drinking. Additionally, many people who smoke also drink alcohol and vice versa, making it challenging to determine if one or both behaviors contribute to the disease. One solution is to employ Mendelian randomization which uses genetics to determine if two variables are linked. Using this statistical approach, Yuan, Chen, Ruan et al. investigated if people who display genetic variants that predispose someone to becoming a smoker or drinker are at greater risk of developing certain digestive disorders. This reduces the possibility of confounding and reverse causation, as any association between genetic variants will have been present since birth, and will have not been impacted by external factors. Yuan, Chen, Ruan et al. used data from two studies that had collected the genetic and health information of thousands of people living in the United Kingdom or Finland. The analyses revealed that genetic variants associated with cigarette smoking increase the risk of 20 of the 24 gastrointestinal diseases investigated. This risk persisted for most of the disorders, even after adjusting for genes linked with alcohol consumption. Further analysis showed that genetic variants linked to heavy drinking increase the risk of duodenal ulcer, alcoholic liver disease, cirrhosis, and chronic pancreatitis. However, accounting for smoking-linked genes eliminated the relationship with duodenal ulcer. These findings suggest that smoking has detrimental effects on gastrointestinal health. Reducing the number of people who start smoking or encouraging smokers to quit may help prevent digestive diseases. Even though there were fewer associations between heavy alcohol consumption and gastrointestinal illness, further studies are needed to investigate this relationship in more depth. Introduction Tobacco smoking and alcohol consumption are leading causes of the global burden of disease and are major contributors to premature mortality (GBD 2016 Alcohol Collaborators, 2018; GBD 2016 Alcohol Collaborators, 2020). Gastrointestinal diseases account for considerable health care use and expenditures, and a holistic approach to lifestyle interventions may result in more health gains and less economic burdens (Peery et al., 2022). Population-based studies have identified tobacco smoking as a risk factor for several gastrointestinal diseases, including gastroesophageal reflux disease (Eusebi et al., 2018), esophageal cancer (Fund WCR and Research AIfC, 2007), Crohn’s disease (Piovani et al., 2019), liver cancer (McGee et al., 2019), and pancreatitis (Yadav and Whitcomb, 2010). Evidence on the association between tobacco smoking and risk of other gastrointestinal diseases is limited and inconsistent. Like smoking, heavy alcohol consumption has been associated with increased risk of several gastrointestinal outcomes, including gastritis (Bujanda, 2000), gastric cancer (Laszkowska et al., 2021), colorectal cancer (McNabb et al., 2020), cirrhosis (Simpson et al., 2019), liver cancer (McGee et al., 2019), and pancreatitis (Yadav and Whitcomb, 2010). However, whether these associations are all causal remains unestablished, since most of the evidence was obtained from observational studies where the results may be biased by reverse causality and confounding. Of note, even though reverse causality may not be an issue in the studies for any of studied gastroenterological outcomes, it might exist for certain gastroenterological diseases causing pain, which smoker patients may try to increase smoking dose to mitigate via an intake of higher levels of nicotine. In addition, as smoking and alcohol consumption are phenotypically and genetically correlated (Roberts et al., 2020; Liu et al., 2019), the independent impacts of smoking and alcohol consumption on gastrointestinal diseases are unclear. Establishing the causal association of tobacco smoking and alcohol consumption with gastrointestinal diseases is crucial, as this provides further evidence for subsequent recommending public policies and clinical interventions. Mendelian randomization (MR) is an epidemiological approach that utilizes genetic variants as an instrument to strengthen the causal inference in an exposure-outcome association (Davey Smith and Hemani, 2014). MR is by nature not prone to confounding since genetic variants are randomly assorted at conception and thus unrelated to environmental and self-adopted factors that usually act as confounders. Additionally, this method can minimize reverse causality since fixed alleles are unaffected by the onset and progression of disease. Previous MR studies have examined the associations of smoking and alcohol consumption with several gastrointestinal diseases (Yuan and Larsson, 2022a; Larsson et al., 2020; Yuan and Larsson, 2022b; Yuan et al., 2022c; Chen et al., 2022; Yuan et al., 2021). Nevertheless, whether smoking and alcohol consumption exert influence on a wide range of gastrointestinal outcomes has not been investigated in a comprehensive way. A thorough investigation on the gastrointestinal consequences of smoking and alcohol drinking is of great importance to develop non-pharmacological interventions on gastrointestinal diseases. Here, we conducted an MR investigation of the associations of smoking and alcohol consumption with the risk of common gastrointestinal diseases to fill in above knowledge gaps. Materials and methods Figure 1 shows the study design overview. The study was based on publicly available genome-wide association studies (GWAS), and the detailed information on used studies was presented in Supplementary file 1A. The genetic associations were estimated using data from the UK Biobank study (Sudlow et al., 2015), the FinnGen study (Kurki et al., 2022; https://www.finngen.fi/en), and several large consortia. The summary effect estimates were combined using meta-analysis for each gastrointestinal disease from different data resources. Included studies had been approved by corresponding institutional review boards and ethical committees, and consent forms had been signed by all participants. Figure 1 Download asset Open asset Overview of the present study design. GERA, Genetic Epidemiology Research on Aging; IIBDGC, the International Inflammatory Bowel Disease Genetics Consortium; MR, Mendelian randomization; MR-PRESSO, Mendelian randomization pleiotropy residual sum and outlier; SNP, single nucleotide polymorphism. Instrumental variable selection A total of 378 and 99 single nucleotide polymorphisms (SNPs) associated with smoking initiation (a binary phenotype indicating whether an individual had ever being a regular smoker, 1,232,091 individuals of European descent) and alcohol consumption (log-transformed drinks per week, 941,280 individuals of European descent) at the genome-wide significance threshold (p<5 × 10–8) were identified by the GWAS and Sequencing Consortium of Alcohol and Nicotine use (GSCAN) study (Liu et al., 2019). These SNPs explained approximately 2.3 and 0.3% of the variation in smoking initiation and alcohol consumption, respectively (Liu et al., 2019). SNPs in linkage disequilibrium (defined as r2 >0.01 or clump distance <10,000 kb) and with the weaker associations with the exposure were removed, leaving 314 independent SNPs as instrumental variables for smoking initiation and 84 for alcohol consumption. Smoking initiation and alcohol consumption shared two index genetic variants, which were rs1713676 and rs11692435. Considering partial sample overlap (around 30%) between the GSCAN study with full data and the UK Biobank study (Liu et al., 2019), we performed sensitivity analyses for smoking initiation and alcohol consumption using summary statistics data from the analysis excluding the UK Biobank and 23andMe. For a supplementary analysis of smoking behavior, we used 126 SNPs associated with a lifetime smoking index that considered smoking duration, heaviness, and cessation (Wootton et al., 2020). The set of genetic instruments captured around 0.36% of the variance in lifetime smoking (Wootton et al., 2020). We also conducted a sensitivity analysis using rs1229984 in ADH1B gene that encodes alcohol dehydrogenase 1B enzyme as the genetic instrument for alcohol consumption to minimize pleiotropy. Detailed information on used SNPs is presented in Supplementary file 1B. Gastrointestinal disease data sources Genetic associations with 24 gastrointestinal diseases were obtained from the UK Biobank study (Sudlow et al., 2015), the FinnGen study (Kurki et al., 2022), and two large consortia, including the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC) (Liu et al., 2015) and Genetic Epidemiology Research on Aging (GERA) (Guindo-Martínez et al., 2021). Included outcomes were classified into four major categories according to the disease onset site: (1) upper gastrointestinal diseases (gastroesophageal reflux disease, esophageal cancer, gastric ulcer, acute gastritis, chronic gastritis, and gastric cancer); (2) lower gastrointestinal diseases (irritable bowel disease, celiac disease, diverticular disease, Crohn’s disease, ulcerative colitis, and colorectal cancer); (3) hepatobiliary and pancreatic diseases (non-alcoholic fatty liver disease, alcoholic liver disease, cirrhosis, liver cancer, cholangitis, cholecystitis, cholelithiasis, acute pancreatitis, chronic pancreatitis, and pancreatic cancer); and (4) other (acute appendicitis). The UK Biobank study is a large multicenter cohort study of 500,000 participants recruited in the United Kingdom between 2006 and 2010 (Sudlow et al., 2015). We used the summary statistics of European ancestry from GWAS conducted by Lee lab, where the gastrointestinal outcomes were defined by codes of the International Classification of Diseases 9th Revision (ICD-9) and ICD-10 (Zhou et al., 2020). Genetic associations were estimated by logistic regression with adjustment for sex, birth year, and the first four genetic principal components. For the FinnGen study, we used summary-level data on the genetic associations with gastrointestinal diseases from the last publicly available R7 data release (Kurki et al., 2022). The FinnGen study is a nationwide genetic study where genetic and electronic health record data were collected. The gastrointestinal diseases were ascertained by the codes of the ICD-8, ICD-9, and ICD-10. Genome-wide association analyses were adjusted for sex, age, genetic components, and genotyping batch. Summary-level genetic data on Crohn’s disease (5956 cases and 14,927 controls) and ulcerative colitis (6968 cases and 20,464 controls) were additionally obtained from the IIBDGC (Liu et al., 2015), and data on irritable bowel syndrome (3117 cases and 53,520 controls) were obtained from the GERA (Guindo-Martínez et al., 2021). Detailed diagnostic codes are listed in Supplementary file 1C. Statistical analysis Data were harmonized to omit ambiguous SNPs with non-concordant alleles and palindromic SNPs with ambiguous minor allele frequency (>0.42 and <0.58) were removed from the analysis. The primary MR analyses were performed by the multiplicative random-effects inverse-variance weighted (IVW) method, which provides the most precise estimates though assuming that all SNPs are valid instruments. The analysis of rs1229984 for alcohol consumption was conducted by the Wald method. Estimates for each association from different sources were combined using fixed-effects meta-analysis, and the heterogeneity of the associations from different data sources was evaluated by the I2 statistic. Heterogeneity among SNPs’ estimates in each association was assessed by Cochran’s Q value. Multivariable MR analyses were conducted to mutually adjust for smoking initiation and alcohol consumption. To detect potential unbalanced pleiotropy (horizontal pleiotropy) and examine the consistency of the associations, three sensitivity analyses including the weighted median (Yavorska and Burgess, 2017), MR-Egger (Burgess and Thompson, 2017), and MR pleiotropy residual sum and outlier (MR-PRESSO) (Verbanck et al., 2018) analyses were performed. The weighted median method can provide consistent estimates when more than 50% of the weight comes from valid instrument variants (Yavorska and Burgess, 2017). The MR-Egger intercept test can detect unmeasured pleiotropy, and MR-Egger regression can generate estimates after accounting for horizontal pleiotropy albeit with less precision (Burgess and Thompson, 2017). The MR-PRESSO method can identify SNP outliers and provide results identical to that from IVW after removal of outliers (Verbanck et al., 2018). The F-statistic was estimated to quantify instrument strength, and an F-statistic >10 suggested a sufficiently strong instrument. Power analysis was performed using an online tool (Brion et al., 2013). The Benjamini-Hochberg correction that controls the false discovery rate was applied to correct for multiple testing. The association with a nominal p-value <0.05 but Benjamini-Hochberg adjusted p-value >0.05 was regarded suggestive, and the association with a Benjamini-Hochberg adjusted p-value <0.05 was deemed significant. All analyses were two-sided and performed using the TwoSampleMR (Hemani et al., 2018), MendelianRandomization (Yavorska and Burgess, 2017), and MRPRESSO R packages (Verbanck et al., 2018) in R software 4.1.2. Results The F-statistic for each genetic variant was above 10, suggesting a good strength of used genetic instruments (Supplementary file 1B). Most associations were well powered (Supplementary file 1D). For smoking initiation, there was 80% power to detect the smallest odds ratio (OR) ranging from 1.08 to 1.40 for included outcomes. Although power was lower for alcohol consumption, it was adequate to detect a moderate effect size for most common gastrointestinal diseases. Smoking and gastrointestinal diseases Genetic predisposition to smoking initiation was associated with 20 of the 24 studied gastrointestinal diseases, and all these associations remained after multiple comparison correction (Table 1 and Supplementary file 1E). In detail, genetic liability to smoking initiation was positively associated with seven upper gastrointestinal diseases: gastroesophageal reflux (OR, 1.28; 95% confidence interval [CI], 1.20–1.37; p=4.09 × 10−14), esophageal cancer (OR, 1.67; 95% CI, 1.24–2.25; p=6.84 × 10−4), gastric ulcer (OR, 1.54; 95% CI, 1.37–1.72; p=3.83 × 10−14), duodenal ulcer (OR, 1.53; 95% CI, 1.34–1.75; p=8.47 × 10−10), acute gastritis (OR, 1.29; 95% CI, 1.09–1.53; p=0.003), chronic gastritis (OR, 1.33; 95% CI, 1.18–1.49; p=1.55 × 10–6), and gastric cancer (OR, 1.42; 95% CI, 1.13–1.79; p=0.003); genetic liability to smoking initiation was positively associated with four lower gastrointestinal diseases: irritable bowel syndrome (OR, 1.22; 95% CI, 1.12–1.32; p=3.50 × 10−6), diverticular disease (OR, 1.25; 95% CI, 1.18–1.33; p=5.23 × 10−14), Crohn’s disease (OR, 1.25; 95% CI, 1.11–1.40; p=3.03 × 10−4), and ulcerative colitis (OR, 1.15; 95% CI, 1.04–1.26; p=0.004); genetic liability to smoking initiation was positively associated with eight hepatobiliary and pancreatic diseases: non-alcoholic fatty liver disease (OR, 1.49; 95% CI, 1.26–1.76; p=3.82 × 10−6), alcoholic liver disease (OR, 1.99; 95% CI, 1.65–2.41; p=1.49 × 10−12), cirrhosis (OR, 1.68; 95% CI, 1.40–2.02; p=3.39 × 10−8), liver cancer (OR, 1.57; 95% CI, 1.13–2.17; p=0.007), cholecystitis (OR, 1.47; 95% CI, 1.29–1.68; p=4.71 × 10−9), cholelithiasis (OR, 1.20; 95% CI, 1.13–1.27; p=5.75 × 10−9), acute pancreatitis (OR, 1.39; 95% CI, 1.23–1.56; p=6.71 × 10−8), and chronic pancreatitis (OR, 1.38; 95% CI, 1.17–1.64; p=1.79 × 10−4); genetic liability to smoking initiation was positively associated with acute appendicitis (OR, 1.15; 95% CI, 1.08–1.23; p=1.27 × 10−5). Results were consistent in sensitivity analyses. An indication of horizontal pleiotropy was observed in the analysis of esophageal cancer in the FinnGen study (p for MR-Egger intercept <0.05, Supplementary file 1F). Although MR-PRESSO detected one to three outliers, the associations persisted and remained significant after removal of these out-lying SNPs (Supplementary file 1F). When using the genetic variants for smoking initiation based on data without the UK Biobank and 23andMe studies, the associations attenuated slightly albeit remained significant after multiple comparisons (Supplementary file 1L and Supplementary file 1G). All associations were replicated in the supplementary analysis of the lifetime smoking index (Supplementary file 1G). After correcting for multiple testing, genetically predicted lifetime smoking index was significantly associated with 17 of 24 gastrointestinal diseases, where the patterns of associations were generally similar to the analysis for smoking initiation (Supplementary file 1M and Supplementary file 1G). In distinction to the analysis of smoking initiation, genetically predicted lifetime smoking index was not significantly associated with acute gastritis, gastric cancer, Crohn’s disease, and ulcerative colitis, whereas genetically predicted lifetime smoking index was significantly associated with pancreatic cancer (OR, 2.09; 95% CI, 1.30–3.36). Table 1 Associations of genetic predisposition to smoking initiation with 24 gastrointestinal diseases in univariable and multivariable Mendelian randomization analyses. DiseaseTotal casesTotal controlsUVMRMVMR adjusted for alcohol consumptionOR (95% CI)p ValueI2 (95% CI)OR (95% CI)p ValueUpper gastrointestinal diseasesGastroesophageal reflux34,135634,6291.28 (1.20, 1.37)4.09 × 10-14*46.241.65 (1.35, 2.02)1.38 × 10-6*Esophageal cancer1130702,1161.67 (1.24, 2.25)6.84 × 10-4*22.684.78 (2.10, 10.90)1.97 × 10-4*Gastric ulcer8651666,8791.54 (1.37, 1.72)3.83 × 10-14*44.961.95 (1.40, 2.71)7.31 × 10-5*Duodenal ulcer5713666,8791.53 (1.34, 1.75)8.47 × 10-10*0.001.64 (1.07, 2.52)0.024Acute gastritis3048643,4781.29 (1.09, 1.53)0.003*0.001.54 (0.91, 2.62)0.106Chronic gastritis7975643,4781.33 (1.18, 1.49)1.55 × 10-6*77.041.33 (0.96, 1.86)0.091Gastric cancer1608701,4721.42 (1.13, 1.79)0.003*0.002.29 (1.14, 4.59)0.020Lower gastrointestinal diseasesIrritable bowel disease15,718641,4891.22 (1.12, 1.32)3.50 × 10-6*11.841.43 (1.10, 1.85)0.008*Celiac disease4808631,7000.82 (0.66, 1.02)0.0710.000.87 (0.53, 1.43)0.590Diverticular disease50,065587,9691.25 (1.18, 1.33)5.23 × 10-14*67.291.56 (1.30, 1.87)1.41 × 10-6*Crohn’s disease10,846645,7181.25 (1.11, 1.40)3.03 × 10-4*0.001.48 (1.01, 2.16)0.042Ulcerative colitis16,770651,2551.15 (1.04, 1.26)0.004*0.000.94 (0.71, 1.25)0.677Colorectal cancer9519686,9531.03 (0.92, 1.14)0.63229.941.03 (0.76, 1.39)0.841Hepatobiliary and pancreatic diseasesNon-alcoholic fatty liver disease3242707,6311.49 (1.26, 1.76)3.82 × 10-6*0.002.11 (1.15, 3.88)0.016*Alcoholic liver disease2955680,3691.99 (1.65, 2.41)1.49 × 10-12*92.682.26 (1.26, 4.03)0.006Cirrhosis5904706,2001.68 (1.40, 2.02)3.39 × 10-8*0.001.92 (1.06, 3.47)0.032Liver cancer714702,0081.57 (1.13, 2.17)0.007*0.001.96 (0.73, 5.25)0.183Cholangitis1708664,7491.02 (0.80, 1.29)0.8920.001.31 (0.61, 2.84)0.489Cholecystitis5893664,7491.47 (1.29, 1.68)4.71 × 10-9*84.722.38 (1.57, 3.60)4.14 × 10-5*Cholelithiasis42,510664,7491.20 (1.13, 1.27)5.75 × 10-9*0.001.33 (1.02, 1.73)0.035Acute pancreatitis6634679,7131.39 (1.23, 1.56)6.71 × (1.04, × (1.06, × (0.92, association after multiple testing. univariable Mendelian randomization; multivariable Mendelian randomization; odds CI, confidence association after multiple testing. In multivariable MR analysis adjusted for genetically predicted alcohol consumption, the associations between genetically predicted smoking initiation and gastrointestinal diseases were consistent with that from univariable MR analysis (Table 1 and Supplementary file However, the associations with in the associations for gastrointestinal reflux, esophageal cancer, gastric ulcer, irritable bowel syndrome, diverticular disease, non-alcoholic fatty liver disease, alcoholic liver disease, and cholecystitis (Table In addition, the association for pancreatic cancer significant from Alcohol consumption and gastrointestinal diseases Genetically predicted alcohol consumption was positively associated with esophageal cancer (OR, 95% CI, duodenal ulcer (OR, 95% CI, alcoholic liver disease (OR, 95% CI, × cirrhosis (OR, 95% CI, and chronic pancreatitis (OR, 95% CI, × and associated with irritable bowel disease (OR, 95% (Table After Benjamini-Hochberg the associations for duodenal ulcer, alcoholic liver disease, cirrhosis, and chronic pancreatitis remained (Supplementary file 1E). Results were consistent in sensitivity and horizontal pleiotropy was detected (Supplementary file One outlier was detected in the analysis of duodenal ulcer in the FinnGen study, and the association slightly after removal of this outlier (Supplementary file Results were consistent in the sensitivity where the genetic associations with alcohol consumption were obtained from the genome-wide association analysis excluding the UK Biobank and 23andMe studies (Supplementary file and Supplementary file 1G). The associations were consistent albeit with in the where alcohol consumption was by rs1229984 (Supplementary file The associations for alcoholic liver disease, cirrhosis, and chronic pancreatitis persisted after adjustment for genetic liability to smoking initiation and multiple correction (Table and Supplementary file Table Associations of genetically predicted alcohol consumption with 24 gastrointestinal diseases in univariable and multivariable Mendelian randomization analyses. DiseaseTotal casesTotal controlsUVMRMVMR adjusted for smoking (95% CI)p ValueI2 (95% CI)OR (95% CI)p ValueUpper gastrointestinal diseasesGastroesophageal (1.18, (1.23, (1.01, gastritis7975643,4781.33 gastrointestinal diseasesIrritable bowel (0.53, (0.76, and pancreatic diseasesNon-alcoholic fatty liver liver × × (1.29, (0.91, (0.91, × × (0.61, association after multiple testing. univariable Mendelian randomization; multivariable Mendelian randomization; odds CI, confidence Discussion We conducted a comprehensive MR investigation to examine the causal of smoking and alcohol consumption in 24 gastrointestinal diseases, and the result summary of this comprehensive analysis is in Figure and Supplementary file We associations between genetic predisposition to smoking and increased risk of gastrointestinal outcomes independent of alcohol consumption, an on gastrointestinal health. In genetically predicted alcohol consumption was and associated with increased risk of liver and pancreatic diseases, including alcoholic liver disease, cirrhosis, and chronic pancreatitis after adjustment for smoking. Figure Download asset Open asset of associations of genetically predicted smoking initiation, lifetime smoking, and alcohol consumption with 24 gastrointestinal diseases. univariable Mendelian randomization; multivariable Mendelian The in the are the odds for associations of exposure for gastrointestinal diseases. The association with a p-value <0.05 but Benjamini-Hochberg adjusted p-value >0.05 was regarded suggestive, and the association with a Benjamini-Hochberg adjusted p-value <0.05 was deemed

People who smoke cigarettes or drink large amounts of alcohol are more likely to develop disorders with their digestive system. But it is difficult to prove that heavy drinking or smoking is the primary cause of these gastrointestinal diseases. For example, it is possible that having a digestive disorder makes people more likely to take up these habits to reduce pain or discomfort caused by the illness (an effect known as reverse causation). The association may also be the result of confounding factors, such as age or diet, which contribute to digestive problems as well as the health outcomes of smoking and drinking. Additionally, many people who smoke also drink alcohol and vice versa, making it challenging to determine if one or both behaviors contribute to the disease. One solution is to employ Mendelian randomization which uses genetics to determine if two variables are linked. Using this statistical approach, Yuan, Chen, Ruan et al. investigated if people who display genetic variants that predispose someone to becoming a smoker or drinker are at greater risk of developing certain digestive disorders. This reduces the possibility of confounding and reverse causation, as any association between genetic variants will have been present since birth, and will have not been impacted by external factors. Yuan, Chen, Ruan et al. used data from two studies that had collected the genetic and health information of thousands of people living in the United Kingdom or Finland. The analyses revealed that genetic variants associated with cigarette smoking increase the risk of 20 of the 24 gastrointestinal diseases investigated. This risk persisted for most of the disorders, even after adjusting for genes linked with alcohol consumption. Further analysis showed that genetic variants linked to heavy drinking increase the risk of duodenal ulcer, alcoholic liver disease, cirrhosis, and chronic pancreatitis. However, accounting for smoking-linked genes eliminated the relationship with duodenal ulcer. These findings suggest that smoking has detrimental effects on gastrointestinal health. Reducing the number of people who start smoking or encouraging smokers to quit may help prevent digestive diseases. Even though there were fewer associations between heavy alcohol consumption and gastrointestinal illness, further studies are needed to investigate this relationship in more depth.

People who smoke cigarettes or drink large amounts of alcohol are more likely to develop disorders with their digestive system. But it is difficult to prove that heavy drinking or smoking is the primary cause of these gastrointestinal diseases. For example, it is possible that having a digestive disorder makes people more likely to take up these habits to reduce pain or discomfort caused by the illness (an effect known as reverse causation). The association may also be the result of confounding factors, such as age or diet, which contribute to digestive problems as well as the health outcomes of smoking and drinking. Additionally, many people who smoke also drink alcohol and vice versa, making it challenging to determine if one or both behaviors contribute to the disease. One solution is to employ Mendelian randomization which uses genetics to determine if two variables are linked. Using this statistical approach, Yuan, Chen, Ruan et al. investigated if people who display genetic variants that predispose someone to becoming a smoker or drinker are at greater risk of developing certain digestive disorders. This reduces the possibility of confounding and reverse causation, as any association between genetic variants will have been present since birth, and will have not been impacted by external factors. Yuan, Chen, Ruan et al. used data from two studies that had collected the genetic and health information of thousands of people living in the United Kingdom or Finland. The analyses revealed that genetic variants associated with cigarette smoking increase the risk of 20 of the 24 gastrointestinal diseases investigated. This risk persisted for most of the disorders, even after adjusting for genes linked with alcohol consumption. Further analysis showed that genetic variants linked to heavy drinking increase the risk of duodenal ulcer, alcoholic liver disease, cirrhosis, and chronic pancreatitis. However, accounting for smoking-linked genes eliminated the relationship with duodenal ulcer. These findings suggest that smoking has detrimental effects on gastrointestinal health. Reducing the number of people who start smoking or encouraging smokers to quit may help prevent digestive diseases. Even though there were fewer associations between heavy alcohol consumption and gastrointestinal illness, further studies are needed to investigate this relationship in more depth.

Liver disease refers to a wide spectrum of both acute conditions caused by various injurious agents, such as viruses, toxins, alcohol and pharmacological agents, as well as chronic liver diseases, which may over time lead to cirrhosis. Cirrhosis, from whatever cause, predisposes to hepatocellular carcinoma, a primary liver cancer, particularly if the cirrhosis is caused by hepatitis B or C infection. Most acute liver diseases can be managed conservatively or by withdrawing the hepatotoxic agent responsible. Severe acute liver damage may result in liver failure, or be so overwhelming as to induce irreversible liver damage (fulminant liver failure), which is associated with significant mortality rates. A proportion of acute infections and diseases may cause ongoing liver injury, resulting in chronic liver disease and cirrhosis. Like acute liver damage, chronic disease often goes undiagnosed during the early stages of the condition. Many cases only present to practitioners when substantial permanent damage has already occurred, at which time signs of liver failure and or cirrhosis are apparent. A minority of cases are detected at an earlier stage, either as a result of screening of families for inherited liver disease or as a result of abnormal liver function being found on blood tests performed during a routine medical examination. The liver is the major organ involved in a number of key metabolic processes. Damaged or reduced functional capacity can result in jaundice, hypoglycaemia, prolonged blood clotting, protein malnutrition, increased risk of infection, confusion, impaired lung and kidney function, fluid retention and fatigue. In addition, severe liver disease is often linked to vague symptoms such as malaise and fatigue, all of which results in significant morbidity, greatly impairing an individual's quality of life. Liver failure of any degree, once present, is associated with a significantly increased risk of premature death. The major liver diseases from a public health perspective are hepatitis C and B infection, alcoholic liver disease, primary liver cancer and haemochromatosis. The substantial public health impact of chronic liver disease can be gauged from the reported death rate per 100 000 population, although the figures may not be truly representative as mortality figures are underestimated in some countries. Data are available for the current EU states (Table 1). The differences observed between countries mainly reflect regional variations in the incidence of hepatitis B and hepatitis C infection (1, 2). Unfortunately, comparative figures for countries on the eastern and southern borders of the European Union are not available. However, World Health Organization data on the incidence of viral hepatitis per 100 000 population clearly shows the very great burden of hepatitis, even with the likelihood of under-reporting. The incidence of hepatitis C is reported as: Czechoslovakia 3.11, Estonia 26.65, Latvia 12.52, Russia 22.12, Ukraine 9.46, Croatia 3.38, Macedonia 1.28, Albania 4.37; and of hepatitis B: Romania 12.01, Russia 44.18, Ukraine 18.85, Belarus 9.34, Georgia 10.22, Moldavia 17.58, Yugoslavia 3.68. These data are relevant as several of these states are joining the European Union in the near future, and in addition many economic migrants and asylum seekers who journey to the European Union originate from this part of the world. It would therefore appear that both hepatitis B- and C-induced liver damage are conditions that will account for significantly more morbidity and mortality in the European Union in the future. Incidence of hepatitis B infection per 100 000 people in Europe. Prevalence of hepatitis C as a percentage of the total population of a region. There are an estimated 5 million carriers of hepatitis C in western Europe, with a higher but not well-documented carriage rate in eastern Europe. In western Europe, hepatitis C accounts for 70% of all cases of chronic hepatitis, 40% of cases of cirrhosis, and 60% of cases of hepatocellular carcinoma. End-stage liver disease resulting from infection now represents the major indication for liver transplant surgery in western Europe. The major route of infection is through blood and blood products. New infections are asymptomatic in 80% of cases. While blood-bank screening is reducing the incidence in western Europe, and universal precautions are also helping, this is not the case in eastern Europe. Occupational and perinatal exposure remain important routes of infection. A large percentage of new cases in western Europe are related to intravenous drug abuse and to the increased prevalence of hepatitis C infection in economic migrants and asylum seekers from eastern Europe and the ex-Soviet republics (Table 2). Unfortunately, 40% of those with an acute infection face life-long chronic infection. Approximately 20% of these develop cirrhosis. Indeed, of the causes of death in those who develop chronic hepatitis, 80% are due to cirrhosis or its complications. Co-infection with hepatitis B is an added risk factor, with chronic hepatitis B being more common in eastern Europe and southern Balkan countries. Once cirrhosis develops, 1–4% of patients per year develop hepatocellular carcinoma. Hepatitis B infection and chronic hepatitis C are both premalignant diseases. Vaccination has been proven to reduce infection rates and the incidence of hepatocellular carcinoma as a result of hepatitis B, following seminal studies in Taiwan. Unfortunately, optimal vaccination schedules have not been achieved in eastern Europe, mainly due to economic restrictions. In the case of hepatitis C, vaccination is not a possibility, and a reliable vaccine is not on the horizon. Treatment for chronic hepatitis C is not yet as effective as could be wished. In all, only 40% of those with genotype 1, prevalent in most countries, respond to combination therapy. Treatment is expensive (several thousand Euro per patient) and lengthy (minimum 6 months). Consequently, prevention is the key to reducing the burden of disease caused by hepatitis C. Even allowing for a slowly falling prevalence of hepatitis C infection in western Europe, there remains a large cohort of currently infected individuals progressing to cirrhosis and primary liver cell cancer, who represent an enormous future health and financial burden to Europe, considering the costs of anti-viral therapy, monitoring tests and treatment of the complications of chronic liver disease. The situation in eastern Europe is worse. Education, public health measures and identification of individuals at pre-cirrhotic stages represent means to diminish overall costs while increasing the benefits of treatment. Hepatocellular carcinoma is a type of primary liver cell cancer whose major risk factors are hepatitis B infection, and cirrhosis due to any cause. Thus, the incidence of hepatocellular carcinoma is linked both to the prevalence of chronic viral hepatitis and to other major additional causes of cirrhosis such as excessive alcohol consumption. Calculations based on reasonable estimates indicate that the current age-adjusted incidence figures will sharply increase during the next few decades. Cancer registry data document annual rates in males in the Mediterranean regions of 10 cases per 100 000, with an estimated incidence in northern Europe of half this figure. Consequently, the number of new cases in Europe as a whole is at least 25 000 per year. Only 50% survive for 1 year if untreated. Smaller diameter tumours and single tumours have improved survival after therapy. However, detection of early tumours suitable for resection and alternative treatments requires surveillance programmes of groups most at risk; hepatitis B-infected individuals and those with cirrhosis, particularly due to hepatitis C and alcohol. Surveillance currently relies on ultrasound techniques in combination with serological markers of hepatocellular carcinoma development. Even though relatively inexpensive, there are no structured, nationally based, surveillance programmes for individuals most at risk and even then the cost–benefit analysis has to be clearly demonstrated. Diseases attributable directly or indirectly to excessive alcohol intake are placing a great burden on healthcare systems. German and UK studies have shown that in 25–40% of all acute medical admissions, alcohol plays a contributory role. A report from the Royal College of Physicians in the UK has estimated that up to 12% of all hospital costs are related to harmful alcohol consumption. Precise figures in Europe are not available but Eurostat does publish death rates per 100 000 related to alcohol abuse, the majority attributable to alcoholic liver disease. In the European Union states these are (in males): Austria 6.3, Belgium 3.6, Denmark 8.5, Finland 7.7, France 6.9, Germany 10.8, Greece 0.9, Ireland 3.2, Italy 0.6, Luxembourg 8.7, Netherlands 1.7, Portugal 1.4, Spain 1.3, Sweden 5, UK 1.1. In addition, in northern Italy, the Dionysos Study reported that 4% of the population had alcoholic liver disease of varying severity. After hepatitis C infection, alcoholic liver disease is currently the second most common indication for liver transplantation throughout European member states. There is concern that alcohol consumption is increasing in adolescents and young adults in many countries, whilst overall per capita consumption is increasing in eastern Europe (Figure 3). Percentage of 15-year-olds consuming alcohol at least once a week by country. Increasing consumption is likely to result in larger numbers of people suffering from associated liver disease in the future. There is an urgent need to identify risk factors, other than total consumption, for the development of significant alcoholic liver disease, cirrhosis and subsequent hepatocellular carcinoma, to allow for the development of targeted healthcare. However, as with hepatitis C infection, public-health promotion and increasing public awareness of the serious complications of excessive alcohol consumption are likely to be key factors in the future reduction of the rates of alcohol-related liver disease. Haemochromatosis is an inherited condition common in northern European countries. The cardinal feature of the disease is iron overload, characterized by deposition of excessive iron in tissues and organs throughout the body, resulting in damage and organ failure over time. The spectrum of conditions associated with iron overload includes liver disease, diabetes, impotence, abnormal skin pigmentation, joint damage and heart disease, including heart failure. Excessive iron overload is associated with a documented increased risk of premature death, with cirrhosis, liver failure, liver cancer and diabetes contributing most to this risk. Many patients with haemochromatosis remain undiagnosed as gradual iron overload occurs for years before patients present with end-organ damage and related symptoms. Increased awareness of the disease has led to an increased incidence, primarily as a result of improved diagnosis and recognition. Early diagnosis is vital as a simple, cost-effective treatment, venesection, is available for patients. Regular removal of units of blood prevents iron deposition and is associated with long-term improved patient survival. Unfortunately, neither diabetes nor cirrhosis, once present, responds to this treatment. Nevertheless, recognition of iron overload in those patients is of vital importance to additional family members who can be screened for the condition by means of a simple blood test, hopefully prior to significant tissue damage occurring. Hereditary haemochromatosis has been estimated to affect between 1 : 1000 and 1 : 3000 people in northern Europe (Figure 4).1–9 The condition becomes less frequent in eastern or southern countries. In 1996, the genetic abnormality responsible for 80–100% of cases was discovered. Identification of the gene has enabled estimation of the gene frequency and therefore those at risk of the condition to be calculated (Table 3).10–19 The genetic data suggests that hereditary haemochromatosis is among one of the most common inherited conditions worldwide, and has led to suggestions that population-based screening would be cost-effective. However, there is some discrepancy between the numbers who carry the genetic risk for the disease and those with actual abnormalities in iron load, consistent with the condition. It is possible that additional unknown genetic factors as well as environmental factors account for this disparity. Until such time as we have a better mean of identifying those who will develop the disease, arguments against the introduction of screening will persist. Prevalence of haemachromatosis in Europe: % population. Acute liver failure, fortunately relatively uncommon, is associated with high mortality rates, despite often multidisciplinary management in an intensive-care setting. Recent data from both Europe and the USA have confirmed that paracetamol overdose remains the most common cause of acute liver failure despite restrictions on its use and the addition of clear warnings on packaging, accounting for almost 40% of cases.20, 21 Additional frequent causes include drug reactions and viral hepatitis. Spontaneous survival rates for acute liver failure vary according to aetiology from between 60 and 70% for paracetamol overdose to as low as 18% for patients with viral hepatitis. Many patients require extreme measures to improve survival; in all 30–40% require emergency liver transplantation. Overall mortality rates for those unable to undergo urgent transplantation have been reported to be as high as 35–57%.21, 22 Similarly, chronic liver diseases, in particular cirrhosis, has a poor prognosis, Recent evidence suggests that cirrhosis reduces the estimated life expectancy by 37 years and by 20 years among 30 and 50-year-olds, respectively.23 In addition, the incidence of hepato-cellular carcinoma in European patients with cirrhosis has been reported to be in the order of 5–6% per annum.24 As well as high mortality rates, chronic liver disease typically results in a significant reduction in the quality of life of the patient. One recent study revealed that patients with moderate to severe liver disease reported similar reductions in all aspects of quality of life to patients recovering from a stroke.25 Such data confirm the significant social impact of liver disease on patients and their families. The financial burden of direct costs alone for liver disease is considerable and set to increase. It has been documented that just over 2% of all hospital discharges in America in 1998 cited a hepatitis C-related diagnosis.26 The estimated direct medical costs for hepatitis C alone during that year was US$1 billion. Medical treatment employing combination interferon-alpha therapy costs €4000−5000 per quality-adjusted year of life gained, and is effective in only about 40% of cases.27 Over one-third of all liver transplants are currently performed for hepatitis C-related conditions, which represents a five-fold increase on figures from 1990. The estimated cost per liver transplant reported in the literature varies from an average of €33 000 to €94 000.28, 29 Another regularly used benchmark of cost, length of hospital stay, is also prolonged for individuals with chronic liver disease, with a reported average of 10.2 days, although specialist gastroenterology consultation can reduce this.30 With future epidemiological projections predicting a four-fold increase in the number of people at risk of chronic liver disease over the next 10–15 years, the enormous financial implications for health services throughout Europe are only too apparent, if significant steps are not taken in attempt to reduce transmission of infective hepatitis and the regular abuse of alcohol among European populations. The costs of treating end-stage liver disease and hepatocellular carcinoma superimposed on cirrhosis are high. Prevention of cirrhosis and thus hepatocellular carcinoma is the key to reducing health care costs and overall disease burden. Prevention of hepatitis B and C infection by vaccination and universal precautions, as well as identification and treatment of chronic hepatitis C patients and reduction of alcohol consumption would all contribute to this objective.

Toll-Like Receptor Signaling in Liver Diseases

Liver Field during Immunotherapy of Hepatocellular Carcinoma: Some Like It Hot

Reply to: Correspondence on “EASL Clinical Practice Guidelines on non-invasive tests for evaluation of liver disease severity and prognosis – 2021 update”

A closer look at the mysterious HSD17B13

Combined alcoholic and non-alcoholic steatohepatitis.

Changes in liver and spleen volumes in alcoholic liver disease

More than 18 million adults in the United States abuse alcohol, a prevalence 5 times higher than that of hepatitis C. Chronic alcohol use of greater than 80 g/day for more than 10 years increases the risk for hepatocellular carcinoma (HCC) approximately 5-fold; alcohol use of less than 80 g/day is associated with a nonsignificant increased risk for HCC. The risk for HCC in decompensated alcohol induced cirrhosis approaches 1% per year. The risk does not decrease with abstinence, and HCC can occur in a noncirrhotic liver. Alcohol use in chronic hepatitis C doubles the risk for HCC as compared with the risk in hepatitis C alone. Furthermore, there may be synergism between alcohol and hepatitis C in the development of HCC, and in these patients HCC may occur at an earlier age and the HCC may be histologically more advanced. Studies in the United States and Italy suggest that alcohol is the most common cause of HCC (accounting for 32%-45% of HCC). The mechanisms by which alcohol causes HCC are incompletely understood, but may include chromosomal loss, oxidative stress, a decreased retinoic acid level in the liver, altered DNA methylation, and genetic susceptibility. Alcohol use is increasing in many countries, suggesting that alcohol will continue to be a common cause of HCC throughout the world.