Key result
Familial combined hyperlipidemia was associated with higher fasting plasma C3 (1.33 vs 0.91 g/L, P=0.01) and ASP levels, along with a delayed postprandial C3 response compared to controls.
Why the study?
Does an oral fat loading test reveal an impaired postprandial complement component 3 (C3) response in patients with familial combined hyperlipidemia compared to matched controls?
Case-Control (n=20)
Does an oral fat loading test reveal an impaired postprandial complement component 3 (C3) response in patients with familial combined hyperlipidemia compared to matched controls?
Patients with familial combined hyperlipidemia exhibit a delayed and exaggerated postprandial complement component 3 response, which may contribute to impaired peripheral free fatty acid uptake and very low density lipoprotein overproduction.
Should not change practice in familial combined hyperlipidemia; leaves open complement C3 dysregulation in its pathogenesis.
Very low density lipoprotein overproduction is the major metabolic characteristic in familial combined hyperlipidemia (FCHL). Peripheral handling of free fatty acids (FFAs) in vitro may be impaired in FCHL by decreased action of acylation-stimulating protein (ASP), which is identical to the immunologically inactive complement component 3a (C3adesArg). Because decreased FFA uptake by impaired complement component 3 (C3) response (as the precursor for ASP) may result in enhanced FFA flux to the liver in FCHL, we have evaluated postprandial C3 changes in vivo in FCHL patients. Accordingly, 10 untreated FCHL patients and 10 matched control subjects underwent an oral fat loading test. Fasting plasma C3 and ASP levels were higher in FCHL patients (1.33+/-0.09 g/L and 70.53+/-4.37 mmol/L, respectively) than in control subjects (0.91+/-0.03 g/L and 43.21+/-8.96 mmol/L, respectively; P=0.01 and P<0.05). In control subjects, C3 concentrations increased significantly after 4 hours (to 1.03+/-0.04 g/L). In FCHL, plasma C3 was unchanged after 4 hours. The earliest postprandial C3 rise in FCHL patients occurred after 8 hours (1.64+/-0.12 g/L). The maximal apolipoprotein B-48 concentration was reached after 6 hours in FCHL patients and control subjects. Postprandial FFA and hydroxybutyric acid (as a marker of hepatic FFA oxidation) were significantly higher in FCHL patients than in control subjects, and the early postprandial C3 rise was negatively correlated with the postprandial FFA and hydroxybutyric acid concentrations. The present data suggest an impaired postprandial plasma C3 response in FCHL patients, most likely as a result of a delayed response by C3, as the precursor for the biologically active ASP, acting on FFA metabolism. Therefore, an impaired postprandial C3 response may be associated with impaired peripheral postprandial FFA uptake and, consequently, lead to increased hepatic FFA flux and very low density lipoprotein overproduction.
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Meijssen et al. (2002) conducted a case-control in Familial Combined Hyperlipidemia (n=20). Familial combined hyperlipidemia vs. Matched control subjects was evaluated on Fasting plasma C3 levels (p=0.01). Familial combined hyperlipidemia was associated with higher fasting plasma C3 (1.33 vs 0.91 g/L, P=0.01) and ASP levels, along with a delayed postprandial C3 response compared to controls.
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