Isolated amyloidosis of pancreatic islets

Isolated amyloidosis of pancreatic islets is one of the most common and well-studied forms of endocrine amyloidosis (APUD-amyloidosis). It is detected in insulin-producing tumors and more than 90% of patients with only non-insulin-dependent diabetes, and more often in the elderly. Therefore, isolated amyloidosis of pancreatic islets is also one of the forms of senile local amyloidosis, occurring among the latter in 24.5% of cases.

[1], [2], [3], [4], [5], [6], [7], [8],

Causes and pathogenesis of amyloidosis of pancreatic islets

It should be borne in mind that isolated amyloidosis of pancreatic islets is not the only manifestation of pancreatic lesions in amyloidosis. Its vessels are affected in all systemic (generalized) forms: AL (primary amyloidosis), AA (secondary amyloidosis), FAP (hereditary amyloidosis, familial amyloid neuropathy), ASCi (systemic senile amyloidosis). With these forms, mainly arteries of different caliber are involved. These lesions in the vast majority of cases do not lead to violations of the pancreas. In cases where amyloidosis of the arteries, especially small ones, is pronounced, atrophy and lipo- matosis of the pancreas are possible with violation of its exocrine function. With isolated amyloidosis of the islets of the pancreas, it is a question of the loss of the endocrine gland function.

The study of isolated amyloidosis of pancreatic islets was initiated by E. L Opie. In 1901, he described in a patient with diabetes mellitus the replacement of pancreatic islets with a homogeneous homogeneous substance that was mistakenly considered hyaline. After 40 years N. Gellerstedt proved the amyloid nature of these changes. In 1970, P. Lacy included isolated amyloidosis of pancreatic islets into the group of senile amyloidosis.

Most researchers recognize the decisive role of B cells in the construction of islet amyloid. Until recently, an islet amyloid was considered an insulin derivative or an insulin beta chain. In 1986-1987 years. Islet amyloid peptide was isolated in pure form from insulin amyloid, and then from islet amyloid in insulin-dependent diabetes. His biochemical analysis showed that the peptide consists of 37 amino acids, and the amino acid sequence is 46% identical to the human neuropeptide: calcitongene-bound peptide-2 (CGSP-2) and CGSP-1 (the peptide name indicates that they are a product of the same gene as and calcitonin). After it was established that the islet amyloid peptide possesses hormonal activity and is contained in the islet apparatus not only in non-insulin-dependent diabetes, but also in norm, it was renamed amylin. The human amylin gene is found in the 12th chromosome (insulin gene - in the 11th chromosome) and has an evolutionary generality with the gene KGSP-1 and KGSP-2.

Immunohistochemically, amylin is found in islet B cells in the same secretory granules as insulin, is present in sufficiently large quantities in the blood of patients with insulin-dependent diabetes. In this case, a correlation is revealed between the active mass of B cells and the possibility of isolating amylin under the influence of pharmacological agents. In elderly and elderly people, the formation of amyloid in pancreatic islets is probably associated with a high local concentration of amylin, and not with damage to its primary structure.

Amyloid pancreatic islets have some features: it does not contain tyrosine and tryptophan, does not react with sera to fibrillar amyloid proteins (AA, AL, ASGi, FAP), but its plasma component is the same as in other types of amyloid. In electron microscopy, amyloid fibrils are found in close contact with B cells on their cytoplasm or intracellularly.

The degree of isolated amyloidosis of the islets of the pancreas varies widely - from minimal deposits in the form of small plaques along the capillaries, more often along the periphery of the pancreatic islets, to the expressed amyloidosis, when almost all of the islet tissue is replaced.

[9], [10], [11], [12], [13], [14],

Symptoms of amyloidosis of pancreatic islets

Symptoms of isolated amyloidosis of pancreatic islets are typical: approximately 70% of patients develop non-insulin dependent diabetes mellitus, with a dependence of the severity of diabetes on the degree of amyloidosis of pancreatic islets, which is confirmed by a morphometric study. In this regard, the discussion of the relationship between diabetes mellitus and isolated amyloidosis of the pancreatic islets (which is primary and what is secondary) can be considered complete - it is not about diabetic amyloidosis of pancreatic islets, but about amyloid diabetes. The diagnosis of isolated amyloidosis of pancreatic islets, unfortunately, is posthumous, although the achievements of modern medical instrumentation and molecular biology could make it in vivo.

Particular attention should be paid to isolated amyloidosis of pancreatic islets as a problem of age. It should be confirmed that senile diabetes is amyloid diabetes. The validity of this statement is evidenced by the fact that after 60 years of age, the frequency of isolated amyloidosis of pancreatic islets increases, reaching a peak after 80 years, especially in women. The clinical manifestations of diabetes are found in 66.6% of cases. Therefore, isolated amyloidosis of the pancreatic islets and becomes one of the components of the Schwarz tetrad as manifestations of polyorganic senile amyloidosis - the heart, vessels, pancreatic islets and brain. However, the Schwartz tetrad is very rare (in 5.5% of autopsies of elderly and senile people). Significantly more often they have isolated amyloidosis of pancreatic islets combined with either isolated atrial amyloidosis and senile amyloidosis of the aorta, or with senile cerebral amyloidosis and senile amyloidosis of the eye.

Thus, isolated amyloidosis of pancreatic islets in the overwhelming majority of cases is a geriatric and gerontological problem.