Circadian, Week-to-Week, and Physical Exercise-Induced Variation of Serum Microfibrillar-Associated Protein 4

Proteomic analysis emphasizes the adaptation of energy metabolism in horses during endurance races

BACKGROUND

Long-term aerobic exercise during endurance racing places high demands on equine homeostasis. This study aimed to use proteomic analysis to elucidate complex biological responses during endurance exercise. It was hypothesized that different serum proteome changes would be noted, reflecting physiological processes as a response to race. The serum has been taken before and after an 80 km race from 13 endurance horses. Proteomic analysis of samples has been performed by TMT-based quantitative method. Apolipoprotein and haptoglobin values have been validated by enzyme-linked immunosorbent assay and biochemical assay respectively. The difference in protein abundance between pre and post-race values has been determined.

RESULTS

In serum samples, 10 master proteins with significant p value differences between pre- and post-race abundances were detected. Increased protein abundance after the race was noted for the apolipoprotein groups: ApoA IV and E, Microfibril-associated glycoprotein 4 (MFAP4), transferrin, and antithrombin-III. Decreases in apolipoprotein C-II, C-III and R, alpha-1-microglobulin/bikunin precursor protein (AMBP) and haptoglobin abundance were reported after the race compared to before the race. Gene Ontology analysis revealed changes in triglyceride and acylglycerol homeostasis, lipid localization regulation, triglyceride catabolic processes, cholesterol binding, antioxidant activity and several cellular components.

CONCLUSIONS

The endurance race caused several homeostatic imbalances characterized by various alterations in serum protein levels. The most pronounced changes emphasize the adaptation of energy metabolism to a more pronounced consumption of lipids.

Declined plasma microfibrillar-associated protein 4 levels in acute coronary syndrome

BACKGROUND

Microfibrillar-associated protein (MFAP4), initially identified as an extracellular matrix protein, has been demonstrated in multiple human disorders, but it is yet to be discovered following acute coronary syndrome (ACS) in clinical practice. Therefore, this study aimed to investigate the relationship between circulating MFAP4 levels and coronary stenosis in ACS.

METHODS

We performed the study in 148 ACS subjects, including 75 ST-segment elevation myocardial infarction (STEMI), 27 non-ST-segment elevation myocardial infarction (non-STEMI) and 46 unstable angina (UA). Clinical variables were collected and Gensini and Syntax stenosis scoring systems were applied to assess the severity of coronary stenosis. Kaplan-Meier and logistic regression analysis were used to analyze the relationship between MFAP4 and the severity of coronary stenosis or ACS outcomes. Spearman analysis was used to describe the correlation between MFAP4 and clinical parameters.

RESULTS

Circulating MFAP4 levels were significantly decreased in the STEMI group (0.008 ng/ml) compared with the non-STEMI group (0.014 ng/ml) and UA group (0.019 ng/ml) (p < 0.001). After adjusting for confounding factors, we found that MFAP4 was an independent risk factor for STEMI (odds ratio = 0.395, 95% CI 0.174-0.895, p = 0.026). MFAP4 level was negatively correlated with Gensini score and Syntax score (r = - 0.311 and - 0.211, p < 0.001 and 0.01, respectively). Based on the MFAP4 level of 0.117 ng/ml, ACS patients were divided into two groups: the low-MFAP4 group (< 0.117 ng/ml, n = 60) and the high-MFAP4 group (≥ 0.117 ng/ml, n = 88). After the median follow-up of 165 days, Kaplan-Meier survival analysis revealed that the MACE-free rate was significantly lower in ACS patients with lower MFAP4 levels (p = 0.009).

CONCLUSIONS

MFAP4 has a potential as a biomarker for the degree of coronary stenosis in ACS. Confirmation of observations in larger cohorts and longer follow-up periods is warranted.