Lipase is a digestive enzyme that converts triglycerides into free fatty acids and glycerol. Lipases are enzymes found in pancreatic secretions that aid in fat digestion. Lipases come in a variety of forms, including hepatic lipases in the liver, hormone-sensitive lipases in adipocytes, lipoprotein lipase on the vascular endothelium surface, and pancreatic lipase in the small intestine. Understanding lipase is critical for understanding the mechanism of fat necrosis and has clinical implications for acute and chronic pancreatitis. Lipase also plays an important role in the mechanism of some cholesterol-lowering medicines. The function, pathogenesis, and clinical importance of the lipase enzyme will be discussed in this review.
The alpha and beta hydrolase folds are the foundation of the lipase family of enzymes. They act by using a histidine base, a serine nucleophile, and aspartic acid in chymotrypsin-like hydrolysis.
Function
Lipase is an enzyme that breaks down triglycerides into glycerol and free fatty acids. Lipases are enzymes that break down fats and are found in pancreatic secretions. Lipases are enzymes that aid in the transport of lipids. Hepatic lipases are found in the liver, hormone-sensitive lipases are found in adipocytes, lipoprotein lipase is found on the vascular endothelium surface, and pancreatic lipase is found in the small intestine, all of which serve various purposes. The triglycerides that remain in intermediate-density lipoprotein are degraded by hepatic lipase in the liver (IDL). Hormone-sensitive lipase is present in fat tissue and is in charge of digesting the triglycerides that adipocytes store.
Lipoprotein lipase is a triglyceride degrading enzyme located on the surface of vascular endothelial cells that is responsible for digesting triglycerides circulating in chylomicrons and VLDLs. Pancreatic lipase is a digestive enzyme that breaks down dietary lipids in the small intestine.
The enzyme hepatic lipase is essential for the production and transport of low-density lipoprotein (LDL). Hepatic lipase modifies intermediate-density lipoprotein in peripheral tissues and the liver to create LDL. These LDL particles are taken up or endocytosed by target cell tissue via receptor-mediated endocytosis. LDL is responsible for carrying cholesterol from the liver to peripheral tissues.
Pathophysiology
Enzymatic and non-enzymatic fat necrosis are also possible. Saponification of peripancreatic fat occurs in acute pancreatitis. Non-enzymatic fat necrosis occurs during traumatic events, such as physical injury to breast tissue. This is because fat cells are damaged, producing the release of lipase, which causes triglyceride breakdown and the release of fatty acids. These negatively charged fatty acids bond to positively charged calcium ions once released into the circulation. Saponification is the process of salt production between negatively charged fatty acids and positively charged calcium ions. Saponified cells appear histologically as dead fat cells that surround the tissue but lack peripheral nuclei. On hematoxylin and eosin staining, saponification of the fatty acid and calcium ion appears dark blue.
Clinical Significance
Serum lipase levels that are abnormally high could indicate pancreatitis. The diagnosis of acute pancreatitis is based on the outcomes of two of the three criteria. Acute epigastric discomfort spreading to the back increased serum amylase or increased lipase levels up to three times the upper limit of normal serum lipase levels is among the diagnostic criteria. This is a more specific diagnostic marker than amylase or CT or MRI imaging. Acute pancreatitis is caused by pancreatic enzymes digesting the pancreas, resulting in edema around the pancreas. Excessive ethanol use, gallstones, trauma, mumps, steroids, autoimmune disease, hypertriglyceridemia with levels above 1000 mg/dL, hypercalcemia, ERCP, Scorpion sting, or drugs such as nucleoside reverse transcriptase inhibitors, protease inhibitors, or sulfa drugs are all potential causes of this pathology. Acute pancreatitis can result in complications such as pseudocysts, in which the pancreatic lining is made up of granulation tissue rather than epithelium, necrosis, abscess, infection, hemorrhage, calcium soap precipitation due to hypocalcemia, or organ failures, such as acute respiratory distress syndrome, shock, or renal failure.
A serum lipase level of >10,000 U/L at presentation in AP is a valuable measure that indicates a biliary origin while essentially ruling out alcoholic AP.
Amylase and lipase
Digestive enzymes like amylase and lipase are essential. Amylase is a digestive enzyme that aids in the breakdown of carbohydrates in the body. Lipase is a digestive enzyme that aids in the digestion of lipids.
The pancreas is a glandular organ located beneath the stomach that produces digestive secretions that pass through the small intestine. In addition to amylase and lipase, the pancreas produces a variety of additional enzymes.
Pancreatitis, or inflammation of the pancreas, generates elevated levels of amylase and lipase in the bloodstream.
Pancreatitis is diagnosed with amylase and lipase testing. The tests determine how much of these enzymes are circulating in your blood. When you have symptoms of acute pancreatitis or another pancreatic condition and your doctor wishes to confirm the diagnosis, these enzymes are usually tested.
Conclusion
Lipase and amylase readings that are greater than normal could indicate pancreatic damage or another illness.
According to the American College of Gastroenterology’s standards, values greater than three times the upper limit of normal usually lead to a diagnosis of pancreatitis (ACG).
Amylase and lipase tests are used to diagnose illnesses like acute pancreatitis. These digestive enzyme blood tests evaluate whether symptoms are caused by low blood amylase and lipase levels. These tests also aid doctors in ruling out certain illnesses.