The protein mixture of cytokine-inducing activity accompanying chicken immunoglobulin Y, named yolkin, consists of several peptides of molecular weight (MW) ranging from over 1 to 35 kDa. Yolkin and its constituent peptides were found to be efficient inducers of interleukin (IL)-1β, IL-6 and IL-10 secretion. N-terminal amino acid sequences of eight of the electrophoretically purified yolkin constituents revealed that all of them are homological to some fragments of the C-terminal domain of vitellogenin II. The fractions of MW about 4 and 12 kDa are free of carbohydrates and start at position 1732 in the vitellogenin amino acid sequence; whereas the other fractions (MW about 16, 19, 23, 29, 32 and 35 kDa) appeared to be glycoproteins corresponding to the amino acid sequence of vitellogenin starting at position 1572. From these data, it is concluded that yolkin most likely represents vitellogenin-derived peptides that possess cytokine-inducing activity and are, at least partially, responsible for such properties of separated immunoglobulin Y preparation. This finding reveals a new role for vitellogenin as a reservoir of polypeptides that may play an important role in the innate immune system of the developing embryo.
The negative association between Alzheimer’s disease (AD) and cancer suggests that susceptibility to one disease may protect against the other. When biological mechanisms of AD and cancer and relationship between them are understood, the unsolved problem of both diseases which still touches the growing human population could be overcome. Actual information about biological mechanisms and common risk factors such as chronic inflammation, age-related metabolic deregulation, and family history is presented here. Common signaling pathways, e.g., p53, Wnt, role of Pin1, and microRNA, are discussed as well. Much attention is also paid to the potential impact of chronic viral, bacterial, and fungal infections that are responsible for the inflammatory pathway in AD and also play a key role to cancer development. New data about common mechanisms in etiopathology of cancer and neurological diseases suggests new therapeutic strategies. Among them, the use of nilotinib, tyrosine kinase inhibitor, protein kinase C, and bexarotene is the most promising.
Immunity transfer from a mother to the newborn does not depend exclusively on immunoglobulins. Peptides, which are characterized by immunoregulatory properties that accompany IgG(2), known as proline-rich polypeptide complex (PRP), have been discovered for the first time in ovine colostrum. In this report we present new data showing that some immunoregulatory peptides associated with the main immunoglobulin class, IgY, are also present in the avian immune system. Cytokine-inducing activity of particular fractions obtained from ovine colostrum, IgG+ (IgG(2) containing PRP), IgG- (IgG(2) free of PRP), and purified PRP, was compared with that of crude egg yolk IgY (IgY+), additionally purified egg yolk IgY (IgY-), and polypeptides accompanying IgY named Yolkin (Y), using an ex vivo model of whole human blood cells. It was shown that both IgG+ fraction and PRP, but not IgG-, stimulated the whole blood cells to release tumor necrosis factor-α and interleukin-1β cytokines. Similar experiments performed with hen's egg IgY preparations showed that IgY+ and Y samples showed higher cytokine-inducing activity than samples additionally purified with the use of size exclusion chromatography (IgY-). The IgY+ at a dose of 100 μg was even more active than the positive lipopolysaccharide control. It was also found that Y is able to stimulate macrophage cell line J774.2 to release nitric oxide. The results obtained suggest that IgY, the main chicken immunoglobulin fraction, is accompanied by additional polypeptides and plays a role of a transporter of biologically active substances, which was observed in the case of colostral IgG.
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