Inflammation in liver fibrosis and atrial fibrillation: A prospective population-based proteomic study

Abstract

Background & aims: Elevated liver stiffness has been associated with atrial fibrillation (AFib) in the general population. The mechanism underlying this association is unclear.

Methods: Participants were recruited from the general population and prospectively enrolled with follow-up for 5 years. The fibrosis-4 (FIB-4) index was used as a surrogate marker for liver fibrosis. Proteomics analysis was performed using the 92-target Olink inflammation panel. Validation was performed using the NAFLD fibrosis score (NFS), aspartate aminotransferase to platelet index (APRI), and repeat confirmation proteomics.

Results: A sample of 11,509 participants with a mean age of 54.0 ± 11.1 years, 51.3% women, and a median FIB-4 index of 0.85 (0.65/1.12), was used. The FIB-4 index was predictive for prevalent (FIB-4 index adjusted odds ratio (aOR) per SD: 1.100 with 95% CI 1.011-1.196; p = 0.026), but not incident AFib (log[FIB-4 index]) adjusted hazard ratio: 1.125 with 95% CI 0.943-1.342, p = 0.19). Elastic net regularized regression identified CCL20, DNER, and CXCL10 for prevalent AFib, and AXIN1, CXCL10, and Flt3L for the log(FIB-4 index) (per SD) as most important in common regulated proteins. The relationship between the FIB-4 index, the identified proteins, and AFib was relevant and reproduced at the 5-year follow-up for CXCL10 after adjusting for confounders (log[FIB-4 index] per SD - CXCL10 [per SD] adjusted β 0.160 with 95% CI 0.127-0.194, p <0.0001; CXCL10 [per SD] - AFib aOR 1.455 with 95% CI 1.217-1.741, p <0.0001), reproduced using the NFS and APRI, and corresponding to increased serum levels.

Conclusions: CXCL10 is linked to liver fibrosis, as determined by the FIB-4 index, and to prevalent AFib.

Impact and implications: How elevated liver stiffness relates to atrial fibrillation in the general population remains to be clarified. We hypothesized that systemic inflammation against a background of liver fibrosis produced from metabolic dysfunction-associated steatotic liver disease (MASLD), is involved in the pathophysiology of atrial fibrillation. Using large-scale targeted proteomics, we found that CXCL10 is related to both liver fibrosis, as defined by the fibrosis-4 index, and to atrial fibrillation. These results can aid evidence-based drug development for patients with atrial fibrillation and MASLD-related liver fibrosis.

Keywords: Atrial fibrillation; C-X-C motif chemokine ligand 10 (CXCL10); Fibrosis-4 index (FIB-4 index); Metabolic dysfunction-associated steatotic liver disease (MASLD); Non-invasive test; Proteomics.

Graphical abstract

Fig. 1

Relationship between the fibrosis-4 index and atrial fibrillation. (A) Relationship between the FIB-4 index and prevalent atrial fibrillation (symbols represent odds ratios and bars represent 95% CIs). Level of significance: p <0.05 is considered as statistically significant. (multivariate logistic regression, z-test) (model 1: n = 11,395 (275 events); model 2: n = 11,335 (274 events); model 3: n = 11,186 (262 events)). (B) Cumulative incidence of atrial fibrillation based on the FIB-4 index (blue line indicates cumulative incidence of atrial fibrillation with FIB-4 index <1.3 and red line indicates cumulative incidence of atrial fibrillation with FIB-4 index ≥1.3). Level of significance: a p <0.05 is considered as statistically significant (Gray’s test). (C) Relationship between the FIB-4 index and incident atrial fibrillation (symbols represent hazard ratios and bars represent 95% CIs). Level of significance: a p <0.05 is considered as statistically significant (Cox competing risk analysis, event = atrial fibrillation, competing event = death, z-test) (model 1: n = 10,796 (246 events, 166 competing events); model 2: n = 10,737 (246 events, 164 competing events); model 3: n = 10,591 (232 events, 159 competing events)). (D) Relationship between the FIB-4 index and NT-proBNP (symbols represent β-estimates and bars represent 95% CIs). Level of significance: p <0.05 is considered as statistically significant (multivariate linear regression, t-test). Model 1: adjusted for age and sex; model 2: additional adjustment for smoking, arterial hypertension, diabetes mellitus, obesity, and dyslipidaemia; model 3: additional adjustment for coronary artery disease and congestive heart failure. FIB-4, fibrosis-4; L, lower; NT-proBNP, N-terminal pro–B-type natriuretic peptide; U, upper.

Fig. 2

Protein expressions in %SD of the overall mean in study participants with a Fibrosis-4 Index ≥1.3 and atrial fibrillation (sorted by Fibrosis-4 Index). Colour scale indicates protein expression rate; green, lower expression, and red, higher expression, compared with the overall mean). AFib, atrial fibrillation; FIB-4, fibrosis-4.

Fig. 3

Selection of the most important proteins related to liver fibrosis and atrial fibrillation. Elastic net regularized regression was used to identify the most relevant circulating proteins in atrial fibrillation and liver fibrosis based on the FIB-4 index on a continuous scale (atrial fibrillation: 10 fold cross-validation AUC = 0.7867, (simple AUC = 0.8202), minimal lambda = 0.004 (10 fold-cross validation), n = 5,672, events = 172, number of proteins = 92, adjusted for age (SD) and sex; log(FIB-4 index): 10-fold cross-validation R² = 0.6173, (simple R² = 0.6302), minimal lambda = 0.005 (10-fold-cross validation), m = 5,741, events = 155, number of proteins = 92, (adjusted for age [SD] and sex). Colour scale indicates the lambda ratios within the spectrum of obtained results, green = lower, and red = higher lambda ratio (Lambda ratios prevalent arial fibrillation: CCL20: 6.868, DNER: 5.872, CXCL10: 4.750; log[fibrosis-4 index]: AXIN1: 97.731, CXCL10: 41.078, FlT3L: 32.026). AUC, area under the curve; AXIN1, Axis inhibition protein 1; CCL20, C-C motif chemokine ligand 20; CXCL10, C-X-C motif chemokine ligand 10; DNER, Delta and Notch-like epidermal growth factor-related receptor; Flt3L: Fms related receptor tyrosine kinase 3 ligand.

Fig. 4

Relationship between circulating inflammatory proteins with the Fibrosis-4 Index and atrial fibrillation. (A) Relationship between the log(FIB-4 index) (per SD) and circulating proteins (symbols represent β-estimates and bars represent 95% CIs). Level of significance: p <0.05 is considered as statistically significant (multivariate linear regression, t-test) (model 1: n = 5,741; model 2: n = 5,704; model 3: n = 5,601). (B) Relationship between the FIB-4 index (categorical ≥1.3 vs. <1.3) and circulating proteins (symbols represent β-estimates and bars represent 95% CIs). Level of significance: p <0.05 is considered as statistically significant (multivariate linear regression, t-test) (model 1: n = 5,741; model 2: n = 5,704; model 3: n = 5,601). (C) Relationship between circulating proteins and atrial fibrillation (symbols represent odds ratios and bars represent 95% CIs). Level of significance: p <0.05 is considered as statistically significant (multivariate logistic regression, z-test) (model 1: n = 5,672 [172 events]; model 2: n = 5,635 [171 events]; model 3: n = 5,543 [162 events]). Model 1: adjusted for age and sex; model 2: additional adjustment for smoking, arterial hypertension, diabetes mellitus, obesity, and dyslipidaemia; model 3: additional adjustment for coronary artery disease and congestive heart failure. AXIN1, Axis inhibition protein 1; CCL20, C-C motif chemokine ligand 20; CXCL10, C-X-C motif chemokine ligand 10; DNER, Delta and Notch-like epidermal growth factor-related receptor; FIB-4, fibrosis-4; Flt3L: Fms related receptor tyrosine kinase 3 ligand; L, lower; OR, odds ratio; U, upper.

Fig. 5

Cumulative incidence of atrial fibrillation based on tertiles of proteins. Green line indicates the first tertile, blue line indicates the second tertile, and red line indicates the third tertile of protein expression. Level of significance: p <0.05 is considered as statistically significant (Gray’s test). AXIN1, Axis inhibition protein 1; CCL20, C-C motif chemokine ligand 20; CXCL10, C-X-C motif chemokine ligand 10; DNER, Delta and Notch-like epidermal growth factor-related receptor; Flt3L: Fms related receptor tyrosine kinase 3 ligand.