What provokes amyloidosis?

Depending on the cause and peculiarities of pathogenesis, idiopathic (primary), acquired (secondary), hereditary (genetic), local amyloidosis, amyloidosis in myeloma and APUD-amyloidosis are distinguished. The most common secondary amyloidosis, which is by origin approaching nonspecific (in particular, immune) reactions. It develops with rheumatoid arthritis, ankylosing spondylitis, tuberculosis, chronic osteomyelitis, bronchoectatic disease, less often with lymphogranulomatosis, kidney, lung and other organs, syphilis, ulcerative colitis, Crohn's disease and Whipple, subacute infective endocarditis, psoriasis, etc. Hereditary amyloidosis in our country is usually associated with a periodic illness, which is transmitted by an autosomal dominant type. In this disease, amyloidosis may be the only manifestation. Less common are other forms of hereditary amyloidosis. In particular, the Portuguese neuropathic amyloidosis is distinguished, characterized by peripheral polyneuropathy, intestinal dysfunction, sometimes by changes in intracardiac conduction, impotence. Amyloid deposits are found in many organs, mainly in the walls of small vessels and nerves. A similar variant of familial amyloidosis is described in Japan, Switzerland, Germany. The Finnish variant is amyloidosis with corneal atrophy and cranial neuropathy. There are also hereditary cardiopathic amyloidosis (Danish type), nephropathic amyloidosis with deafness, fever and urticaria. Unlike secondary and hereditary amyloidosis in primary amyloidosis, it is not possible to establish the cause or hereditary nature of the disease. The structure of amyloid and the nature of the defeat of internal organs to primary amyloidosis is close to amyloidosis in myeloma, which is isolated in a separate group. Recently, attention is paid to the development of amyloidosis in senile age (especially in people older than 70-80 years) when the brain, aorta, heart, pancreas are affected. New forms of amyloidosis, in particular amyloidosis, are described in patients on chronic hemodialysis, characterized by destructive arthropathy, carpal tunnel syndrome and bone defects. The nature of the relationship between amyloidosis and atherosclerosis has not been clarified to date, although there are indications that atheromatous changes may contribute to the deposition of amyloid.

APUD amyloidosis is a special kind of local endocrine form of amyloidosis, in which the formation of the main component of amyloid fibril comes from the products of the cells of the APUD system (apudocytes). This disease often develops with apodomas, tumors from APUD-cells. APUD-amyloidosis includes amyloidosis of the thyroid stroma in medullary cancer, pancreatic islets, amyloidosis of parathyroid glands with adenoma, pituitary gland, and also isolated senile amyloidosis of the atria.

Recently, it is proposed to subdivide amyloidosis by the biochemical composition of amyloid fibrils.

• AA-amyloid is the most common amyloid protein, the analog of which in the serum is the protein SAA. This type of amyloid protein is found in secondary amyloidosis and amyloidosis with a periodic illness. Its serum precursor (SAA) is a protein that is present in the serum in acute inflammation, tumors, pregnancy, rheumatic diseases and other conditions. It is shown that SAA protein is synthesized by hepatocytes, the initiator of its synthesis is interleukin 1.
• AF-amyloid is detected in hereditary forms of amyloid polyneuropathy. It is likely that the serum AF precursor is one of the polymorphic forms of normal prealbumin. AL-amyloid consists of Ig and fragments of Ig light chains.
• In the 80s patients who had been on hemodialysis for a long time began to often detect carpal tunnel syndrome caused by the deposition of amyloid in the synovium (AN-amyloid). β ₂ -Microglobulin is a serum precursor of this type of amyloid protein.
• AS-amyloid is observed in a clinically heterogeneous group of elderly patients. The serum precursor of this type of amyloid protein is prealbumin.