The Involvement of Phospholipases A₂ in Asthma and Chronic Obstructive Pulmonary Disease

Table 2

Mechanism of action and function of human phospholipase A₂ enzymes. Adapted and modified from [1, 4, 5].

Name	Mechanism of action	Function		Sources
		Physiology	Pathophysiology
Secretory phospholipases A2 (sPLA2s)	(i) Enzymatic (liberation of AA and lysophospholipids); (ii) Autocrine and paracrine action by binding to N-type and M-type receptors or by binding to integrins	(i) Lipid remodeling for membrane homeostasis; (ii) Exocytosis; (iii) Phagocytosis; (iv) Anticoagulant activity; (v) Antibacterial activity (Gram-positive and Gram-negative bacteria); (vi) Antifungal and antiadenoviral activity; (vii) Parturition; (viii) Spinal processing of nociception	(i) Inflammatory diseases (rheumatoid arthritis, adult respiratory distress syndrome, inflammatory bowel disease, and pancreatitis); (ii) Sepsis; (iii) Atherosclerosis (foam cell formation); (iv) Cancer; (v) Surfactant hydrolysis	Neutrophils, eosinophils, basophils, T-cells, monocytes, macrophages, platelets, mast cells, airway epithelial cells, alveolar type II epithelial cells,
Cytosolic phospholipases A2 (cPLA2s)	(i) enzymatic: lysophospholipase and transacylase activity	(i) AA releasing; (ii) Cellular signaling; (iii) Parturition; (iv) Nociception	(i) Inflammation; (ii) Intestinal ulceration; (iii) Psoriasis; (iv) Acute lung injury; (v) Polyposis; (vi) Brain injury; (vii) Anaphylaxis	Every tissue
Ca^2+-independent phospholipases; A2 (iPLA2s)	VIA, VIB, VIC, VID, VIEVIF-phospholipase A2 activity; VIC-lysophospholipase activity; VID-adiponutrin-like activity; VIE-triglyceride lipase activity; VIF-transacylase activity	(i) Remodeling of phospholipids; (ii) AA releasing; (iii) Protein expression; (iv) Acetylcholine-mediated endothelium-dependent relaxation of the vasculature; (v) Apoptosis; (vi) Insulin secretion; (vii) Bone formation; (viii) Sperm development; (ix) Cell proliferation; (x) Activation of Ca^2+ influx; (xi) Axon regeneration in nerve injury (VIA)	(i) Wallerian degeneration (VIA); (ii) regulation of monocyte migration (VIB); (iii) Oxidant-induced cell injury (VIC); (iv) Ischemia-induced ventricular tachyarrhythmias	(i) Alveolar cells; (ii) Macrophages; (iii) Normal and cancer lung tissue; (iv) Neurons
	aiPLA2-phospholipase A2 and peroxiredoxin 6 activity	(i) Degradation and recycling of surfactant phospholipids (remodeling of phosphatidylcholine to dipalmitoyl-phosphatidylcholine (DPPC); (ii) Antioxidative activity	(i) lung cancer, mesothelioma, sarcoidosis	(i) Alveolar macrophages; (ii) Type II epithelial cells; (iii) Clara cells
Lysosomal phospholipase A2	(i) Acyl-ceramide synthase; (ii) Transacylase activity; (iii) Lysophospholipase activity	(i) may be the crucial enzyme of pulmonary surfactant phospholipid degradation by alveolar macrophages	(i) Phospholipidosis; (ii) Complement activation; (iii) Induced lung injury	(i) Alveolar macrophages; (ii) Peripheral blood monocytes
PAF acetylhydrolases (PAF-AH) or Lipoprotein-associated phospholipases A2	(i) Phospholipase A2 activity	(i) Anti-inflammatory properties by hydrolyzing platelet activating factor (PAF); (ii) Protection against oxidative stress; (iii) Brain development	(i) Generation of lysophospholipids and fatty acid hydroperoxides (ROS); (ii) Acute respiratory distress syndrome; (iii) Marker of coronary heart disease; (iv) Miller-Diker lissencephaly	(i) Alveolar macrophages; (ii) Epithelial type II cells
Adipose-specific phospholipase A2	(i) Phospholipase A1 and A2 activity	(i) catalyzes the release of fatty acids from phospholipids in adipose tissue	(i) Obesity; (ii) Metabolic syndrome	Adipose tissue