Antitumor activity and carrier properties of novel hemocyanins coupled to a mimotope of GD2 ganglioside.

Conjugation to carrier proteins is a way to improve the immunogenicity of peptides. Such is the case for peptides mimicking carbohydrate tumor-associated antigens in cancer vaccine development. The most used protein for this purpose is the keyhole limpet hemocyanin (KLH) from Megathura crenulata. Its limited bioavailability has prompted interest in finding new candidates; nevertheless, it is not known whether other hemocyanins might be equally efficient as carrier of carbohydrate peptide mimotopes to promotes anti-tumor responses. Here, we evaluated the carrier and antitumor activity of novel hemocyanins with documented immunogenicity obtained from Concholepas concholepas (CCH) and Fissurella latimarginata (FLH), coupled through sulfo-SMCC to P10, a mimetic peptide of GD2, the major ganglioside constituent of neuroectodermal tumors, and incorporating AddaVax as an adjuvant. The humoral immune responses of mice showed that CCH-P10 and FLH-P10 conjugates elicited specific IgM and IgG antibodies against P10 mimotope, similar to those obtained with KLH-P10, which was used as a positive control. The CCH-P10 and FLH-P10 antisera, exhibited cross-reactivity with murine and human melanoma cells, like anti-CCH and anti-FLH sera suggesting a cross-reaction of CCH and FLH glycosylations with carbohydrate epitopes on the tumor cell surfaces, similar to the KLH antisera. When mice were primed with each hemocyanin-P10 and challenged with melanoma cells, better antitumor effects were observed for FLH-P10 than for CCH-P10 and, as for KLH-P10, irrespective of conjugation. These data demonstrate that CCH and FLH are useful carriers of carbohydrate mimotopes; however, the best antitumor activity of FLH preparations, indicate that is a suitable candidate for further cancer vaccines research.

Sublethal doses of dinophysistoxin-1 and okadaic acid stimulate secretion of inflammatory factors on innate immune cells: Negative health consequences.

One of the proposed mechanisms to explain why Diarrhetic Shellfish Poison (DSP) toxins are tumor promoters is founded on the capacity of these toxins to increase TNF-α secretion. Although macrophages are the principal cells in the activation of the inflammatory response, the immune profile that Okadaic acid (OA) and Dinophysistoxin-1 (DTX-1) trigger in these cells has not been fully explored. We have therefore investigated the effect of various concentrations of both toxins on the activity of several inflammatory factors. Our results demonstrate that OA and DTX-1, at sublethal doses, stimulate secretion of inflammatory factors. Nevertheless DTX-1 was more potent than OA in increasing TNF-α and IL-6 as well as their dependent chemokines KC, MCP-1, LIX, MIP-1 α, MIP-1 ß and MIP-2. On the other hand, secretion of IFN-γ and the anti-inflammatory cytokines, IL-4 and IL-10, was unaffected. In addition, DTX-1 also raises matrix metalloproteinase-9 (MMP-9) activity. In this study, for the first time the effect of OA and DTX-1 over the secretion of pro-inflammatory and carcinogenic signals in macrophages are compared, showing that DTX-1 is ten times more potent that OA. The inflammatory profile produced by DTX-1 is shown for the first time. The safe limit regulation should be changed to DSP toxins zero tolerance in the shellfish to be consumed by humans.

Hemocyanins Stimulate Innate Immunity by Inducing Different Temporal Patterns of Proinflammatory Cytokine Expression in Macrophages.

Hemocyanins induce a potent Th1-dominant immune response with beneficial clinical outcomes when used as a carrier/adjuvant in vaccines and nonspecific immunostimulant in cancer. However, the mechanisms by which hemocyanins trigger innate immune responses, leading to beneficial adaptive immune responses, are unknown. This response is triggered by a proinflammatory signal from various components, of which macrophages are an essential part. To understand how these proteins influence macrophage response, we investigated the effects of mollusks hemocyanins with varying structural and immunological properties, including hemocyanins from Concholepas concholepas, Fissurella latimarginata, and Megathura crenulata (keyhole limpet hemocyanin), on cultures of peritoneal macrophages. Hemocyanins were phagocytosed and slowly processed. Analysis of this process showed differential gene expression along with protein levels of proinflammatory markers, including IL-1ß, IL-6, IL-12p40, and TNF-α. An extended expression analysis of 84 cytokines during a 24-h period showed a robust proinflammatory response for F. latimarginata hemocyanin in comparison with keyhole limpet hemocyanin and C. concholepas hemocyanin, which was characterized by an increase in the transcript levels of M1 cytokines involved in leukocyte recruitment. These cytokine genes included chemokines (Cxcl1, Cxcl3, Cxcl5, Ccl2, and Ccl3), ILs (Il1b and Ifng), growth factors (Csf2 and Csf3), and TNF family members (Cd40lg). The protein levels of certain cytokines were increased. However, every hemocyanin maintains downregulated key M2 cytokine genes, including Il4 and Il5 Collectively, our data demonstrate that hemocyanins are able to trigger the release of proinflammatory factors with different patterns of cytokine expression, suggesting differential signaling pathways and transcriptional network mechanisms that lead to the activation of M1-polarized macrophages.

A novel immunomodulatory hemocyanin from the limpet Fissurella latimarginata promotes potent anti-tumor activity in melanoma.

Hemocyanins, the huge oxygen-transporting glycoproteins of some mollusks, are used as immunomodulatory proteins with proven anti-cancer properties. The biodiversity of hemocyanins has promoted interest in identifying new anti-cancer candidates with improved immunological properties. Hemocyanins promote Th1 responses without known side effects, which make them ideal for long-term sustained treatment of cancer. In this study, we evaluated a novel hemocyanin from the limpet/gastropod Fissurella latimarginata (FLH). This protein has the typical hollow, cylindrical structure of other known hemocyanins, such as the keyhole limpet hemocyanin (KLH) and the Concholepas hemocyanin (CCH). FLH, like the KLH isoforms, is composed of a single type of polypeptide with exposed N- and O-linked oligosaccharides. However, its immunogenicity was significantly greater than that of KLH and CCH, as FLH induced a stronger humoral immune response and had more potent anti-tumor activity, delaying tumor growth and increasing the survival of mice challenged with B16F10 melanoma cells, in prophylactic and therapeutic settings. Additionally, FLH-treated mice demonstrated increased IFN-γ production and higher numbers of tumor-infiltrating CD4(+) lymphocytes. Furthermore, in vitro assays demonstrated that FLH, but not CCH or KLH, stimulated the rapid production of pro-inflammatory cytokines (IL-6, IL-12, IL-23 and TNF-α) by dendritic cells, triggering a pro-inflammatory milieu that may explain its enhanced immunological activity. Moreover, this effect was abolished when deglycosylated FLH was used, suggesting that carbohydrates play a crucial role in the innate immune recognition of this protein. Altogether, our data demonstrate that FLH possesses increased anti-tumor activity in part because it activates a more potent innate immune response in comparison to other known hemocyanins. In conclusion, FLH is a potential new marine adjuvant for immunization and possible cancer immunotherapy.