Lipolysis of polyenoic fatty acid esters of human chylomicrons by lipoprotein lipase

Our plain-English summary of Lipolysis of polyenoic fatty acid esters of human chylomicrons by lipoprotein lipase, by B. Ekström, A. Nilsson, B. Akesson (European Journal of Clinical Investigation, 1989).

The study

• Authors: B. Ekström, A. Nilsson, B. Akesson
• Journal: European Journal of Clinical Investigation
• Published: 1989;19(3):259-64
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Human chylomicrons, obtained from chylous pleural fluid of a patient with mesothelioma, were incubated with bovine milk lipoprotein lipase. No difference in the release of different C16-C18 fatty acids as unesterified fatty acids, or in their appearance in diacylglycerols, was observed. The rate of lipolysis of arachidonic (20:4), and eicosapentaenoic (20:5) acid ester bonds of chylomicron triacylglycerols was slower, and a larger proportion of these fatty acids accumulated in mono- and diacylglycerols. The hydrolysis pattern for docosahexaenoic acid (22:6) was intermediary between that of the C16-C18 fatty acids and that of 20:4 and 20:5. The data suggest that the presence of a double bond at position 5 in the eicosanoid precursors may be important for the rate of lipolysis. The relative resistance of the 20:4- and 20:5- esters of chylomicrons to lipoprotein lipase may be important for the tissue distribution of these fatty acids.

In plain English

This was a laboratory study of how an enzyme breaks down fats carried in chylomicrons, which are fat-carrying particles that come from the gut. It was not a study of asbestos exposure, and the article does not mention asbestos. The authors took chylomicrons from the drained pleural fluid of one patient with malignant mesothelioma. They incubated them with lipoprotein lipase, an enzyme from cow's milk, for 5 to 120 minutes, in five incubations. They then measured how different fatty acids were released. Common fatty acids with 16 to 18 carbons were released in a very similar way. Three long polyunsaturated fatty acids behaved differently: arachidonic acid (20:4), eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6). All three left the triacylglycerol fraction more slowly and were released as free fatty acids to a lower extent. Arachidonic and eicosapentaenoic acids built up markedly in diacylglycerols and monoacylglycerols. Docosahexaenoic acid built up less and fell between the two patterns. In most comparisons the differences were significant at p less than 0.01. The authors concluded that this build-up is probably a normal physiological process that might affect how these fatty acids are carried to and taken up by body tissues.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) experiment: human chylomicrons incubated with an enzyme, lipoprotein lipase
• Who was studied: Chylomicrons prepared from the drained pleural fluid of one patient with malignant mesothelioma who was on a semi-liquid diet; five incubations (University of Lund, Sweden)
• Exposure: No asbestos exposure was studied or mentioned. The experimental treatment was bovine milk lipoprotein lipase, with incubation times of 5 to 120 minutes.
• Main results:
  • Fatty acids with 16 to 18 carbons were distributed among the lipid fractions in a very similar way, close to the pattern for total fatty acid
  • The authors reported that the highly unsaturated fatty acids (20:4, 20:5 and 22:6) left triacylglycerol more slowly, accumulated in diacylglycerol and monoacylglycerol, and appeared less as free fatty acid
  • The proportion of 20:4 in monoacylglycerol rose from 0.7 to 2.6% between 5 and 120 minutes of incubation; 20:5 in monoacylglycerol rose from 0.2 to 1.7%
  • Differences between these polyunsaturated fatty acids and total fatty acid were significant at p less than 0.01 (Friedman's test) in most cases, and at p less than 0.05 in most of the others
  • Docosahexaenoic acid (22:6) was released as free fatty acid less than the 16 to 18 carbon fatty acids but more than 20:4 and 20:5
  • Docosahexaenoic acid (22:6) left triacylglycerol only slightly faster than 20:4 and 20:5 and built up less in partial glycerides
• The authors' conclusion: The authors concluded that the build-up of these highly polyunsaturated fatty acids in partial glycerides is probably a physiological phenomenon that might influence their transport and tissue uptake.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma.

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