Effect of eicosapentaenoic acid on cholesterol gallstone formation in C57BL/6J mice

Associations of fatty acids with the risk of biliary tract calculus and inflammation: a Mendelian randomization study

BACKGROUND

The presence of gallstones in both the gallbladder and bile ducts is referred to as cholelithiasis. The prevalence of cholecystolithiasis and bile duct stones differs. Observational and Mendelian randomization (MR) studies have elucidated the significant contributing role of numerous fatty acids (FAs) in the development of cholelithiasis. Despite numerous studies about cholelithiasis, evidence on the relationship between serum FA levels and cholecystolithiasis, as well as bile duct stones with or without inflammation, remains insufficient.

METHODS

A two-sample MR study was designed to clarify the impact of serum FA levels on various bile duct inflammatory diseases. The summary statistics of single nucleotide polymorphisms (SNPs) associated with fatty acids were obtained from the UK Biobank (UKB) and included data from 114,999 participants. The researchers obtained GWAS summary statistics for cholecystolithiasis and bile duct stones in 463,010 and 361,194 European participants, including cases with and without inflammation. No sample overlap between the exposure and outcome was verified through the "mr-lap" package. The SNPs were screened to identify instrumental variables (IVs). Cochran's Q test was applied for heterogeneity assessment. Inverse variance weighting (IVW) (fixed effects or random effects), MR-Egger regression and weighted median methods were used for MR. Multivariable MR was applied to determine the direct effect of each exposure on the outcome. A false discovery rate (FDR) was applied to adjust for multiple testing correction based on the Benjamini-Hochberg method. Finally, the FinnGen Consortium was used to validate some results.

RESULTS

The overall concentration of polyunsaturated fatty acids (PUFAs) in the serum was negatively associated with the risk of calculus of the gallbladder with acute cholecystitis (IVW, OR = 0.996, P = 0.038, CI 0.992-0.999; weighted median, OR = 0.995, P = 0.025, CI 0.991-0.999). The percentage of PUFAs to total monounsaturated fatty acids(MUFAs) (IVW, OR = 0.998, P = 0.045, CI 0.997-0.999) and the percentage of PUFAs to total FAs (IVW, OR = 0.997, P = 0.025, CI 0.995-0.999) had a protective role against cholecystitis. The percentage of PUFAs to total FAs had a protective role against calculus of the gallbladder without cholecystitis (IVW, OR = 0.995, P = 0.026, CI 0.990-0.999; MR Egger, OR = 0.99, P = 0.03, CI 0.982-0.998; weighted median, OR = 0.991, P = 5.41e-06, CI 0.988-0.995). Conversely, the percentage of MUFAs to total FAs increased the risk for cholecystitis (IVW, OR = 1.001, P = 0.034, CI 1.0001-1.002). However, there were no causal effects of the above exposures on the outcomes through multivariable MR and multiple testing correction. Finally, the causal effects of the above exposures on cholecystitis were validated in the FinnGen Consortium, which suggested that the percentage of PUFAs to total FAs (IVW, OR = 0.744, P = 0.021, CI 0.579-0.957) had a protective role against cholecystitis.

CONCLUSION

These Mendelian randomization findings suggested that more attention should be focused on people who have low serum PUFA levels, which may have a potential role in the occurrence of calculus of the gallbladder or cholecystitis rather than calculus of the bile duct without cholangitis or cholecystitis.

Identification of blood metabolites linked to the risk of cholelithiasis: a comprehensive Mendelian randomization study

BACKGROUND AND AIMS

Observational and Mendelian randomization (MR) studies have identified several modifiable risk factors of cholelithiasis. However, there is limited evidence about the causal effect of blood metabolites on the cholelithiasis risk.

METHODS

To have a comprehensive understanding to causal relations between blood metabolites and cholelithiasis, for the primary discovery, we applied two MR methods to explore the associations between 249 circulating metabolites and cholelithiasis. For secondary validations, we replicated the examinations using another metabolic dataset with 123 metabolites. The summary statistics of cholelithiasis were retrieved from FinnGen Consortium Release 5 and UK Biobank. Inverse-variance weighted, weight median and MR-egger methods were used for calculating causal estimates. Furthermore, Bayesian model averaging MR (MR-BMA) method was employed to detect the dominant causal metabolic traits with adjustment for pleiotropy effects.

RESULTS

In the primary analysis, sphingomyelin showed consistent protective causal associations with cholelithiasis; while plasma cholesterol-associated traits showed generally inverse correlation with cholelithiasis risk. Notably, large numbers of traits within the (un)saturated fatty acid category demonstrated significant causal effects. Secondary analyses demonstrated similar results, with traits related to the levels of bisallylic groups in fatty acids showing protective effects. Lastly, MR-BMA analyses discovered that the degree of unsaturation plays a predominant role in reducing the risk of cholelithiasis.

CONCLUSION

Our MR study provides a complete atlas of associations between plasma metabolites on cholelithiasis risk. It highlighted that genetically predicted sphingomyelin and degree of unsaturation of fatty acid were causally associated with the reduced risk of cholelithiasis.

High dietary ω-6:ω-3 PUFA ratio and simple carbohydrates as a potential risk factors for gallstone disease: A cross-sectional study

BACKGROUND & AIMS

Gallstone disease (GD) is a major cause for consultation at general surgery services worldwide. In fact, GD has a strong relationship with environmental factors. However, specific characteristics in the Mexican population have not been established. The aim of this study was to compare the dietary components, physical activity, body composition and serum lipids in women with and without GD.

METHODS

54 women with GD and 75 without GD from West Mexico were enrolled in a cross-sectional study. Dietary intake was obtained through a habitual day food record and analyzed using the Nutritionist Pro™ software. Physical activity was evaluated in accordance with WHO recommendations. Body fat percentage (BF%) was estimated by bioimpedance (InBody 370) and serum lipids were measured using dry chemistry (Vitros-250 Analyzer). Student's t-test and binary logistic regression model were used.

RESULTS

Women with GD presented a higher BF% (40 ± 8.7 vs 35.21 ± 9.8%, p = 0.004), an elevated dietary ω-6:ω-3 polyunsaturated fatty acids (PUFA) ratio (18.0 ± 11.4 vs 10.9 ± 4.7, p<0.001) and a higher simple carbohydrates (sCH) intake (28.3 ± 17.8 vs 13.23 ± 8.2%, p<0.001) as well as lower HDL-cholesterol levels (37.43 ± 8.5 vs 46.6 ± 12.02 mg/dL, p<0.001) compared with women without GD. Furthermore, it was foun d a higher ω-6:ω-3 PUFA ratio (OR: 3.9, 95% CI 1.52-10.38, p = 0.005) and excessive sCH consumption (OR: 7.4, 95% CI 1.92-28.65, p = 0.004).

CONCLUSION

We suggest that a high dietary ω-6:ω-3 PUFA ratio and an excessive sCH intake are associated with an increased risk of GD in women.

Prevention of Cholesterol Gallstone Formation by Lactobacillus acidophilus ATCC 43121 and Lactobacillus fermentum MF27 in Lithogenic Diet-Induced Mice

The objective of this study was to evaluate the effects of Lactobacillus acidophilus ATCC 43121 and L. fermentum MF27 on biochemical indices in the serum, cholesterol metabolism in the liver and mucin expression in the gallbladder in lithogenic diet (LD)-induced C57BL/6J mice to determine the preventive effects of lactobacilli on gallstone formation. By the end of 4 wk of the experimental period, mice fed on a LD with high-fat and high-cholesterol exhibited higher levels of total and low-density lipoprotein cholesterol in the serum compared to mice fed on control diet or LD with L. acidophilus ATCC 43121 (LD+P1; p<0.05). Cholesterol-lowering effects observed in the LD+P1 and LD with L. fermentum MF27 (LD+P2) groups were associated with reduced expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase in the liver compared to the LD group (p<0.05). Furthermore, expression of the gel-forming mucin, including MUC5AB and MUC5B, was suppressed in the LD+P1 and LD+P2 groups compared to the LD group (p<0.05). Therefore, steady intake of both L. acidophilus ATCC 43121 and L. fermentum MF27 may have the ability to prevent the formation of cholesterol gallstones in LD-induced C57BL/6J mice.