Evidence for two cholesterol ester hydrolases in human cerebrospinal fluid

Area of Science:

• Biochemistry
• Neuroscience
• Enzymology

Background:

• Cholesterol ester hydrolase (CEH) plays a role in lipid metabolism.
• Investigating CEH in human cerebrospinal fluid (CSF) is crucial for understanding neurological conditions.
• Cerebrospinal fluid enzyme activity can serve as a biomarker for central nervous system disorders.

Purpose of the Study:

• To characterize the properties of cholesterol ester hydrolase in human CSF.
• To compare CEH activity levels in CSF from multiple sclerosis (MS) patients and non-MS individuals.
• To investigate the potential link between CEH activity and demyelination in MS.

Main Methods:

• Assessed pH optima and detergent requirements of human CSF CEH.
• Examined the effects of various lipids, including phosphatidylethanolamine (PE) and phosphatidylserine (PS), on CEH activity.
• Compared CEH activity at different pH values in CSF samples from MS patients and healthy controls.

Main Results:

• Human CSF CEH exhibited two pH optima: pH 6.0 (with Triton X-100) and pH 7.0 (with sodium taurocholate).
• Lipids PE and PS differentially modulated CEH activity at the two pH optima, suggesting distinct enzyme forms.
• Significantly lower CEH activity at pH 7.0 was observed in CSF from MS patients compared to non-MS individuals.

Conclusions:

• The data suggest the presence of at least two distinct cholesterol ester hydrolases in human CSF.
• CEH activity at pH 6.0 may originate from brain microsomal enzymes, while activity at pH 7.0 may be associated with myelin enzymes.
• Reduced pH 7.0 CEH activity in MS patients' CSF is potentially linked to demyelination processes in the central nervous system.