Inherited human cPLA2α deficiency is associated with impaired eicosanoid biosynthesis, small intestinal ulceration, and platelet dysfunction
David H. Adler, Joy D. Cogan, John A. Phillips III, Nathalie Schnetz-Boutaud, Ginger L. Milne, Tina Iverson, Jeffrey A. Stein, David A. Brenner, Jason D. Morrow, Olivier Boutaud, John A. Oates
David H. Adler, Joy D. Cogan, John A. Phillips III, Nathalie Schnetz-Boutaud, Ginger L. Milne, Tina Iverson, Jeffrey A. Stein, David A. Brenner, Jason D. Morrow, Olivier Boutaud, John A. Oates
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Research Article Genetics

Inherited human cPLA2α deficiency is associated with impaired eicosanoid biosynthesis, small intestinal ulceration, and platelet dysfunction

Abstract

Cytosolic phospholipase A2α (cPLA2α) hydrolyzes arachidonic acid from cellular membrane phospholipids, thereby providing enzymatic substrates for the synthesis of eicosanoids, such as prostaglandins and leukotrienes. Considerable understanding of cPLA2α function has been derived from investigations of the enzyme and from cPLA2α-null mice, but knowledge of discrete roles for this enzyme in humans is limited. We investigated a patient hypothesized to have an inherited prostanoid biosynthesis deficiency due to his multiple, complicated small intestinal ulcers despite no use of cyclooxygenase inhibitors. Levels of thromboxane B2 and 12-hydroxyeicosatetraenoic acid produced by platelets and leukotriene B4 released from calcium ionophore–activated blood were markedly reduced, indicating defective enzymatic release of the arachidonic acid substrate for the corresponding cyclooxygenase and lipoxygenases. Platelet aggregation and degranulation induced by adenosine diphosphate or collagen were diminished but were normal in response to arachidonic acid. Two heterozygous single base pair mutations and a known SNP were found in the coding regions of the patient’s cPLA2α genes (p.[Ser111Pro]+[Arg485His; Lys651Arg]). The total PLA2 activity in sonicated platelets was diminished, and the urinary metabolites of prostacyclin, prostaglandin E2, prostaglandin D2, and thromboxane A2 were also reduced. These findings characterize what we believe is a novel inherited deficiency of cPLA2.

Authors

David H. Adler, Joy D. Cogan, John A. Phillips III, Nathalie Schnetz-Boutaud, Ginger L. Milne, Tina Iverson, Jeffrey A. Stein, David A. Brenner, Jason D. Morrow, Olivier Boutaud, John A. Oates

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Figure 5

Platelet aggregation and dense granule release.

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Platelet aggregation and dense granule release. (A) Representative measu...
(A) Representative measurements of platelet aggregation and simultaneous ATP release. Left panel shows aggregation (blue) and ATP release (black) in platelets from a normal control in response to ADP (10 μM). Middle panel shows aggregation (blue and red, performed in duplicate) and ATP release (black and green, in duplicate) in platelets from the proband in response to ADP (10 μM). Right panel shows aggregation (blue and red, in duplicate) and ATP release (black and green, in duplicate) in platelets from the proband in response to AA (500 μM). (B) Optical platelet aggregation in PRP in response to ADP (5 μM) or collagen (2 μg/ml) and ATP release as a measure of platelet degranulation recorded simultaneously during platelet aggregation. Each point represents 1 measurement (different days for the patient and different control volunteers); horizontal bars represent mean.