Lipidomic profiling reveals free fatty acid alterations in plasma from patients with atrial fibrillation

<div><p>Atrial fibrillation (AF) is the most common cardiac arrhythmia, and its incidence is increasing worldwide. One method used to restore sinus rhythm is direct current cardioversion (DCCV). Despite the high success rate of DCCV, AF typically recurs within the first 2 weeks. However, our understanding of the pathophysiology of AF recurrence, incidence, and progression are highly limited. Lipidomic profiling was applied to identify altered lipids in plasma from patients with AF using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry coupled with multivariate statistical analysis. Partial least-squares discriminant analysis revealed a clear separation between AF patients and healthy controls. The levels of several lipid species, including fatty acids and phospholipids, were different between AF patients and healthy controls, indicating that oxidative stress and inflammation are associated with the pathogenesis of AF. Similar patterns were also detected between recurrent and non-recurrent AF patients. These results suggest that the elevated saturated fatty acid and reduced polyunsaturated fatty acid levels in AF patients may be associated with enhanced inflammation and that free fatty acid levels may play a crucial role in the development and progression of AF.</p></div

Lipidomic profiling reveals free fatty acid alterations in plasma from patients with atrial fibrillation

<div><p>Atrial fibrillation (AF) is the most common cardiac arrhythmia, and its incidence is increasing worldwide. One method used to restore sinus rhythm is direct current cardioversion (DCCV). Despite the high success rate of DCCV, AF typically recurs within the first 2 weeks. However, our understanding of the pathophysiology of AF recurrence, incidence, and progression are highly limited. Lipidomic profiling was applied to identify altered lipids in plasma from patients with AF using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry coupled with multivariate statistical analysis. Partial least-squares discriminant analysis revealed a clear separation between AF patients and healthy controls. The levels of several lipid species, including fatty acids and phospholipids, were different between AF patients and healthy controls, indicating that oxidative stress and inflammation are associated with the pathogenesis of AF. Similar patterns were also detected between recurrent and non-recurrent AF patients. These results suggest that the elevated saturated fatty acid and reduced polyunsaturated fatty acid levels in AF patients may be associated with enhanced inflammation and that free fatty acid levels may play a crucial role in the development and progression of AF.</p></div

Lipidomic profiling reveals free fatty acid alterations in plasma from patients with atrial fibrillation - Fig 2

<p>Intensities of free fatty acids in plasma samples obtained from healthy controls and AF patients and (A) and non-recurrent and recurrent AF patients (B). P values were calculated using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.</p

Intensities and compositions of free fatty acids (% of total free fatty acids) in plasma samples obtained from healthy controls and AF patients.

<p>Intensities and compositions of free fatty acids (% of total free fatty acids) in plasma samples obtained from healthy controls and AF patients.</p

Relative mRNA levels of inflammatory cytokines in plasma samples obtained from healthy controls and AF patients.

<p>A, IL-1β (healthy controls, n = 6; AF patients, n = 4); B, TNF-α (healthy controls, n = 6; AF patients, n = 6). P values were calculated using the Mann–Whitney U test. *p<0.05, **p<0.01.</p

Clinical characteristics of healthy controls and patients with AF.

<p>Clinical characteristics of healthy controls and patients with AF.</p

Lipidomic profiling reveals free fatty acid alterations in plasma from patients with atrial fibrillation - Fig 3

<p>Compositions of SFAs, MUFAs, and PUFAs (% of total free fatty acids) in plasma samples obtained from healthy controls and AF patients (A) and non-recurrent and recurrent AF patients (B). Data are presented as means ± standard deviations. P values were calculated using the Mann–Whitney U test. **p < 0.01, ***p < 0.001.</p

(A) Effects of DBM on body weight in an HFD-induced obesity model.

<p>The three groups were as follows: LFD, low-fat (standard) diet; HFD, high-fat diet; and HFD supplemented with 100 mg/kg/d DBM. (B) Effects of DBM on epididymal fat in an HFD-induced obesity model. (C) Effects of DBM on peri-renal fat in an HFD-induced obesity model. (D) Effects of DBM on fatty liver in an HFD-induced obesity model. (E) Effects of DBM on insulin level of HFD-induced animals. * p < 0.05, as compared with basal condition. _* + p < 0.05, as compared with HFD condition (F) Effects of DBM on fasting blood glucose (FBG) level of HFD-induced animals. * p < 0.05, as compared with basal condition. (G) Effects of DBM on leptin level of HFD-induced animals. * p < 0.05, as compared with basal condition. (H) 3T3-L1 pre-adipocyte cells were stimulated for indicated times with DBM. The cells were then lysed with lysis buffer, and the phosphorylation of acetyl CoA carboxylase (ACC) was assessed by western blot using antibodies specific for the phosphorylate protein. The levels of ACC were also assessed. The levels of β-actin were also measured as a control for protein loading. * p < 0.05, as compared with basal condition. The results are representative of three independent experiments. (I) Total mRNA was prepared from DBM-treated 3T3-L1 cells, and RT-PCR was conducted using specific indicated primers. The PCR products were then separated on 1% agarose gels and visualized under ultraviolet light. Beta-actin was used as a loading control. * p < 0.05, as compared with basal condition. (J) ST3-L1 cells were transiently transfected with AMPKα2 siRNA for 48 h. The cells were then stimulated with 30 μM DBM for 1 h. Total mRNA was prepared from DBM-treated 3T3-L1 cells and RT-PCR was conducted using specific fatty acid synthase (FAS) primers. The PCR products were then separated on 1% agarose gels and visualized under ultraviolet light. Beta-actin was used as a loading control. * p < 0.05, as compared with basal condition.</p

(A) C2C12 cells were stimulated with different concentrations of DBM for 1 h.

<p>The cells were lysed with lysis sample buffer, and the phosphorylation of p38 MAPK was evaluated by western blot using antibodies specific for the phosphorylated protein. The levels of total p38 MAPK were also assessed as a control for protein loading. * p < 0.05, as compared with basal condition. The results are representative of four independent experiments. (B) C2C12 cells were stimulated with 30 μM DBM for 1 h in the presence of compound C (1 μM). The cells were lysed with lysis buffer, and the phosphorylation of p38 MAPK was evaluated by western blot using phosphorylation-specific antibody. The levels of total p38 MAPK were also assessed as a control for protein loading. * p < 0.05, as compared with basal condition. Data are representative of four independent experiments. (C) Myoblast L6 cells were differentiated for 7 days and then incubated with the p38 MAPK inhibitor, SB203580, for 20 min, before cells were incubated with DBM for 18 hours. 2-DG uptake was then measured. *p < 0.05, compared with control. **p < 0.05, compared with DBM-treated cells. This result is representative of four independent experiments.</p

(A) C2C12 cells were stimulated for 1 h with various concentrations of DBM.

<p>The cells were then lysed with lysis buffer, and the phosphorylation of AMPKα was assessed by western blot using antibodies specific for the phosphorylated protein. The level of total AMPKα was also assessed as a control for protein loading. (B) C2C12 cells were treated with 30 μM DBM for the times indicated. The cells were lysed with lysis buffer, and the phosphorylation of AMPKα was evaluated by western blot using antibodies specific for the phosphorylated protein. The level of total AMPKα was also assessed as a control for protein loading. (C) C2C12 cells were treated with DBM and curcumin for 1 h. The cells were lysed with lysis buffer, and the phosphorylation of AMPKα and ACC was evaluated using antibodies specific for the phosphorylated protein. The level of total AMPKα and ACC was also assessed as a control for protein loading. (D) L6 myotubes were differentiated for 7 days and then treated with 30 μM DBM and 2 mM metformin for 18 h. 2-deoxy-D [H³] glucose (2-DG) uptake was then assayed, as described in the Methods. * p < 0.05, as compared with basal condition. The results presented are representative of three individual experiments.</p