A cholesterol crystal is a solid,

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

line form of

cholesterol Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils. Cholesterol is biosynthesis, biosynthesized by all anima ...

found in

gallstone A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of ...

s and

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...

. Gallstones occurring in industrialized societies typically contain more than 70-90% cholesterol by weight, much of which is crystalline. Cholesterol crystals are a hallmark of atherosclerosis, which is believed to be an early cause of atherosclerotic

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

. Cholesterol

phase transition In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic Sta ...

from liquid to crystalline form is linked to inflammation. Cholesterol crystals are believed to induce inflammation by activation of the

NLRP3 NLR family pyrin domain containing 3 (NLRP3) (previously known as NACHT, LRR, and PYD domains-containing protein 3 ALP3and cryopyrin), is a protein that in humans is encoded by the ''NLRP3'' gene located on the long arm of chromosome 1. NLRP ...

inflammasome Inflammasomes are cytosolic multiprotein complexes of the innate immune system responsible for the activation of inflammatory responses and cell death. They are formed as a result of specific cytosolic pattern recognition receptors (PRRs) sens ...

. In addition to being a source of inflammation, cholesterol crystals are believed to cause mechanical injury by tearing tissue, causing plaque rupture. Impaired removal of cholesterol crystals from demyelinated nerves by

macrophage Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

s is believed to be associated with

multiple sclerosis Multiple sclerosis (MS) is an autoimmune disease resulting in damage to myelinthe insulating covers of nerve cellsin the brain and spinal cord. As a demyelinating disease, MS disrupts the nervous system's ability to Action potential, transmit ...

, and this remyelination failure is particularly impaired in the elderly.

References

{{circulatory-stub Cardiovascular diseases Gallbladder disorders Medical conditions related to obesity