Novel proteomic signatures may indicate MRI-assessed intrahepatic fat state and changes; the DIRECT PLUS clinical trial

Objective:We demonstrated in the randomized 18-month DIRECT PLUS trial (n=294) that a Mediterranean (MED) diet, supplemented with polyphenol-rich Mankai duckweed, green tea, and walnuts and restricted in red/processed meat, caused substantial intrahepatic fat (IHF%) loss compared with two other healthy diets, reducing NAFLD by half, regardless similar weight loss. Here, we investigated the baseline proteomic profile associated with IHF% and the changes in proteomics associated with IHF% changes induced by lifestyle intervention. Methods:We calculated IHF% by proton-magnetic-resonance-spectroscopy (H-MRS; normal-IHF%<5%; abnormal-IHF%>=5%). We assayed baseline and 18-month samples for 95 proteomic biomarkers. Results:Participants (age=51.3 +/- 10.8years; 89%men; body-mass-index=31.3 +/- 3.9 kg/m(2)) had an 89.8% 18-month-retention-rate; 83% had eligible follow-up proteomics-measurements, and 78% had follow-up H-MRS. At baseline, 39-candidate-proteins were significantly associated with IHF% (FDR<0.05), mostly related to immune-function-pathways (e.g., HAOX1). An IHF%-prediction based on the DIRECT PLUS by combined-model (R-2=0.47, RMSE=1.05) successfully predicted IHF% (R-2=0.53) during testing and was stronger than separately-inputting-proteins/traditional markers (R-2=0.43/0.44). The 18-month lifestyle intervention induced changes in 18 of the 39-candidate-proteins, which were significantly associated with IHF% change, with proteins related to metabolism, extracellular-matrix-remodeling, and immune-function pathways. THBS2 protein-change was higher in the green-MED compared to the MED group, beyond weight-and-IHF%-loss (p-value=0.01). Protein principal-component-analysis revealed differences in the 3rd-principal-component time-distinct interactions across abnormal/normal-IHF% trajectory combinations; p<0.05 for all). Conclusions:Our findings suggest novel proteomic signatures that may indicate MRI-assessed intrahepatic fat state and changes during lifestyle intervention. Specifically, CA5A, HAOX1, and THBS2 protein changes are independently associated with IHF% change, and THBS2 protein change is greater in the green-MED/high-polyphenols diet.