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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A proline-rich polypeptide isolated from sheep colostrum is described. The molecular weight of the polypeptide determined by gel filtration is 17 200. However, in the presence of guanidinium chloride the molecular weight found is about 6000. The polypeptide contains about 22% of proline, a high proportion of non-polar amino acids, a low percentage of glycine, and no alanine, arginine and cysteine residues. The only N-terminal amino acid found is leucine. C.d. spectra in water and in 50% (v/v) trifluoroethanol suggest the presence of block sequences of proline residues forming helices of polyproline II type. The proline-rich polypeptide is soluble at 4 degrees C but is reversibly precipitated on warming to room temperature. Maximal precipitation is observed at pH 4.6 and at ionic strength above 0.6. The precipitation depends on the concentration of the polypeptide. No effect of other proteins, Ca2+ and Zn2+ ions on the precipitation of the polypeptide was found. The proline-rich polypeptide is not an amphipathic protein. The lack of effect of the polypeptide on proteolytic enzymes ruled out the possibility that it is an inhibitor of proteinases.

The aim of this study was to elucidate the structure and possible function of colostrinin, also known as a proline rich polypeptide (PRP). The molecular weight of colostrinin was originally determined by gel filtration to be 17,200 daltons. In the presence of guanidinum chloride, however, the molecular weight was found to be about 6,000 daltons. Further studies utilizing high-performance liquid chromatography (HPLC) and mass spectroscopy revealed that colostrinin is a complex consisting of many low molecular-weight polypeptides. A total of 32 peptides were isolated from the original colostrinin preparation by HPLC and subjected to the N-terminal sequence analysis. The results of sequence analysis revealed significant homology of the peptides to three protein precursors: annexin, beta-casein, and a hypothetical beta-casein homolog. In addition, the sequence of several peptides showed no significant homology to any specific protein in the current GenBank database. The synthetic peptides of various lengths representing the N-terminal sequence of the colostrinin peptides were made to study some biological effects. Here we report that colostrinin and some of its component peptides are potent inducers of leukocyte proliferation and of certain cytokines. Also, a series of monospecific antibodies were produced in rabbits against the synthetic peptides. The antibodies were used to study the kinetic of antigen reduction in colostrum and mature milk following lambing. A threefold decrease was common for most antigens studied over the period of 72 h. Based on the results of these studies we postulate that colostrinin represents a diverse group of peptides produced in the mammary gland of mammals for the development of the optimal physiologic responses in offspring. Also, it is hoped that the beneficial use of colostrinin in Alzheimer's Disease (AD), recently reported elsewhere, will revive interest in its clinical application for treatment and/or prophylaxis of many age-related disorders.

A proline-rich polypeptide complex (PRP), subsequently called Colostrinin(CLN), was first isolated from ovine colostrum, was shown to possess immunoregulatory properties, including effects on the maturation and differentiation of murine thymocytes and humoral and cellular immune responses, both in vivo and in vitro. PRP seems to restore balance in cellular immune functions and is not species specific. PRP is a complex of peptides of molecular masses ranging from 500 to 3000 Da. The polypeptide contains 25% proline and 40% hydrophobic amino acids. PRP shows a regulatory activity in cytokine (IFN, TNF-alpha, IL-6, IL-10) induction and possesses the ability to inhibit the overproduction of oxygen reactive species and nitric oxide. Besides its immunoregulatory activity, PRP also showed psychotropic properties, improving cognitive activity and behavior of old rats, humans, and chickens. The properties of PRP prompted the authors to propose the complex for the treatment neurodegenerative disorders. Beneficial effects of PRP/Colostrinin were shown for the first time in double-blind placebo-controlled trials and long-term open-label studies. The results were confirmed in multicenter clinical trials. A very important property of PRP/Colostrinin is the prevention of Abeta aggregation and the disruption of already existing aggregates. The same properties were expressed by one of PRP's components, a nonapeptide (NP). Moreover, PRP modulates neurite outgrowth, suppresses uncontrolled activation of cells, reduces 4-HNE-mediated cellular damage, and modulates expression in cellular redox regulation, cell proliferation, and differentiation. Its biological response modifying activity can play an important role in its use in the treatment of Alzheimer's disease.

In the hen immune system the egg content plays as significant a role in the development of the chick as colostrum does in newborn mammals. One of the most important proteins in this system seems to be the main yolk immunoglobulin IgY. It has been shown that IgY is accompanied by an immunostimulatory polypeptide complex named yolkin. In this report the biological activities of yolkin separated by means of four different procedures are presented. It was shown that yolkin acts as an inducer rather than a modulator of cytokine and nitric oxide release, and does not participate in the protection of cells against destructive effects of reactive oxygen species. However, using the perchloric acid procedure it is possible to obtain a peptide fraction with higher inducing activity, stronger antioxidant properties and ability to decrease the NO level induced by lipopolysaccharide. The results obtained show that it is feasible to select one of the presented methods of yolkin isolation that yields a product of particular activity. The properties of yolk peptides not only indicate their roles in the development of chicks, but can also be useful for the regulation of some immunological disturbances.