Anti-cancer immunoprotective effects of immunization with hydatid cyst wall antigens in a non-immunogenic and metastatic triple-negative murine mammary carcinoma model

Mining parasites for their potential as novel therapeutic agents against cancer

Despite recent advances in the management and therapeutic of cancer, the treatment of the disease is limited by its high cost and severe side effects. In this scenario, there is an unmet need to identify novel treatment alternatives for this dreaded disease. Recently there is growing evidence that parasites may cause anticancer effects because of a negative correlation between parasitic infections and tumour growth despite some parasites that are known to exhibit pro-carcinogenic effects. It has been observed that parasites exert an anticancer effect either by activating the host's immune response or by secreting certain molecules that exhibit anticancer potential. The activation of the immune response by these parasitic organisms results in the inhibition of some of the hallmarks of cancer such as tumour proliferation, angiogenesis, and metastasis. This review summarizes the current advances as well as the mechanisms underlying the possible implications of this diverse group of organisms as anticancer agents.

Investigating the effect of parasites (toxoplasma gondii RH strain, Leishmania major (MRHO/IR/75/ER), and hydatid cyst) antigens on Alzheimer's disease: An in vivo evaluation

This study aimed to investigate the effects of parasite antigens on Alzheimer's symptoms in animal model. Alzheimer's model was induced in Wistar rats using Amyloid-beta peptide, and treated with parasite crude antigens from T. gondii RH strain, L. major (MRHO/IR/75/ER), and HC. Spectrophotometry and real-time PCR were used to evaluate the oxidative stress levels, antioxidant enzyme activity, and gene expression of NLRP3, IL-8, IL-1β, and Caspase-1. Histological assays were performed to investigate structural changes in the hippocampus. Apoptosis was analyzed using an Annexin V Apoptosis by Flow cytometer. The levels of total oxidant, antioxidant, and SOD increased in the Alzheimer's group compared with the control group, but these factors were lower in the L. major group. The apoptosis in the treated groups was lower compared to the Alzheimer's group. IL-8 expression was significantly higher in all Alzheimer's groups, but decreased in the HC and L. major treated group compared to Alzheimer's. IL-1β and Caspase-1 expression were similarly increased in all groups compared with the control group, but decreased in the antigen-treated groups compared with Alzheimer's. NLRP3 expression was increased in all groups compared with the control group, with lower expression in HC group, but significantly decreased in L. major group compared with Alzheimer's. In histological results, only L. major group could play a therapeutic role in pathological damage of the hippocampus. The results showed that parasite antigens, specifically L. major antigens, may have neuroprotective effects that reduce oxidative stress, apoptosis, and histopathological changes in response to AD in animal model.

Parasites as potential targets for cancer immunotherapy

Parasites and cancers have some common antigens. Much scientific evidence in the human population, animal models, and in vitro experiments exhibit that parasites have significant anti-cancer effects. The larval stage of the tapeworm Echinococcus granulosus, Toxoplasma gondii, Trypanosoma cruzy, Plasmodium's, and Trichinella spiralis are among the parasites that have been subjects of anti-cancer research in the last decades. Anti-tumor effects of parasites may be due to the direct impact of the parasites per se or indirectly due to the immune response raised against common antigens between malignant cells and parasites. This manuscript reviews the anti-cancer effects of parasites and possible mechanisms of these effects. Options for using parasites or their antigens for cancer treatment in the future have been discussed.

Shedding light on a mysterious link between Toxoplasma Gondii and cancer: A review

The ongoing conflict regarding the affiliation of Toxoplasma gondii to cancer; whether an inducer or a suppressor needs to be resolved. Human epidemiological studies oscillate without attaining a firm ground. Some studies confirmed the detection of high seroprevalence of anti-Toxoplasma antibodies in different cancer patients without further justification whether being causation, co-incidences, or part of opportunistic infections. Others reported a state of resistance to cancer accompanying low titer of anti-Toxoplasma antibody. Worthwhile, preclinical experimental work confirmed the antineoplastic potency of Toxoplasma. Thus, further investigational research is essential to validate the potential application of Toxoplasma as a promising cancer immunotherapeutic vaccine candidate. In this paper, we present a review of this issue by examining epidemiological and preclinical experimental studies that explored the linkage between Toxoplasma gondii and cancer<i.></i> We consider this review an important step towards shedding a light on this mysterious link and a stepping-stone for potential research work addressing Toxoplasma as a cancer suppressor rather than a cancer inducer.

Prophylactic antineoplastic activity of Toxoplasma gondii RH derived antigen against ehrlich solid carcinoma with evidence of shared antigens by comparative immunoblotting

BACKGROUND

With cancer cases escalation, an urgent request to develop novel combating strategies arise. Pathogen-based cancer-immunotherapy is getting more consideration. Autoclaved parasitic antigens seem promising candidates, taking steadily their first steps. Our aim was to examine the prophylactic antineoplastic activity of autoclaved Toxoplasma vaccine (ATV) and to test for the shared antigen theory between Toxoplasma gondii and cancer cells.

METHODS

Mice were immunized with ATV followed by Ehrlich solid carcinoma (ESC) inoculation. Tumor weight, volume, histopathology, and immunohistochemistry for CD8⁺ T cells, Treg cells and VEGF were assessed. In addition, the proposed shared antigen theory between parasites and cancer was also verified using SDS-PAGE and immunoblotting.

RESULTS

Results revealed powerful prophylactic activity of ATV with 13.3% inhibition of ESC incidence, significant reduction in tumor weight and volume in ATV vaccinated mice. Immunologically, significantly higher CD8⁺T cells and lower FOXP3⁺ Treg cells surrounded and infiltrated ESC in ATV immunized mice with higher CD8⁺T/Treg cells ratio and significant antiangiogenic effect. Moreover, SDS-PAGE and immunoblotting showed four shared bands between Ehrlich carcinoma and ATV of approximate molecular weights 60, 26, 22 and 12.5 KDa.

CONCLUSION

Exclusively, we demonstrated a prophylactic antineoplastic activity of autoclaved Toxoplasma vaccine against ESC. Moreover, to the best of our knowledge this is the first report highlighting the existence of cross-reactive antigens between Toxoplasma gondi parasite and cancer cells of Ehrlich carcinoma.

Design and functional preliminary investigation of recombinant antigen EgG1Y162-EgG1Y162 against Echinococcus granulosus

In the early stage, our research group cloned Echinococcus granulosus-specific antigen, EgG1Y162, from protoscolex and adult worms of E. granulosus. In order to enhance the immunogenicity of the vaccine, we prepared a recombinant vaccine by tandemly linking EgG1Y162, splicing the protein and linker at the gene level. This approach is expected to improve the immunogenicity of the vaccine by enhancing the molecular weight of the protein and increasing the antigenic epitopes. Bioinformatics was used to predict the physicochemical properties, transmembrane domain, protein structure, and T-/B-cell antigenic epitope of different recombinant proteins, EgG1Y162-linker-EgG1Y162. Finally, the linker sequence, "GGGGSGGG," which had the least influence on the migration of recombinant protein T/B epitope and can fold normally in series with EgG1Y162, was selected to design the recombinant vaccine. The plasmid was produced using genetic engineering techniques, and the recombinant protein, EGG1Y162-GGGGSGGG-EgG1Y162, was induced to be expressed and purified. EgG1Y162-GGGGSGGG-EgG1Y162 was identified to be correctly expressed with 100% specificity. Compared with EgG1Y162, EgG1Y162-GGGGSGGG-EgG1Y162 was more likely to promote dendritic cell maturation. EgG1Y162-GGGGSGGG-EgG1Y162 was speculated to have the potential to improve antigen immunogenicity by increasing the molecular weight and antigenic epitope.

Epitope-based minigene vaccine targeting fibroblast activation protein α induces specific immune responses and anti-tumor effects in 4 T1 murine breast cancer model

Fibroblast activation protein (FAPα) is a tumor stromal antigen expressed by cancer-associated fibroblasts (CAFs) in more than 90 % of malignant epithelial carcinomas. FAPα-based immunotherapy has been reported and showed that FAPα-specific immune response can remold immune microenvironment and contribute to tumor regression. Many FAPα-based vaccines have been investigated in preclinical trials, which can elicit strong and durable cytolytic T lymphocytes (CTL) with good safety. However, epitope-based FAPα vaccines are rarely reported. To break tolerance against self-antigens, analogue epitopes with modified peptides at the anchor residues are typically used to improve epitope immunogenicity. To investigate the feasibility of a FAPα epitope-based vaccine for cancer immunotherapy in vivo, we conducted a preclinical study to identify a homologous CTL epitope of human and mouse FAPα and obtained its analogue epitope in BALB/c mice, and explored the anti-tumor activity of their minigene vaccines in 4 T1 tumor-bearing mice. By using in silico epitope prediction tools and immunogenicity assays, immunodominant epitope FAP.291 (YYFSWLTWV) and its analogue epitope FAP.291I9 (YYFSWLTWI) were identified. The FAP.291-based epitope minigene vaccine successfully stimulated CTLs targeting CAFs and exhibited anti-tumor activity in a 4 T1 murine breast cancer model. Furthermore, although the analogue epitope FAP.291I9 enhanced FAP.291-specific immune responses, improvement of anti-tumor immunity effects was not observed. Check of immunosuppressive factors revealed that the high levels of IL-10, IL-13, myeloid-derived suppressor cells and iNOS induced by FAP.291I9 increased, which considered the main cause of the failure of the analogue epitope-based vaccine. Thus, we demonstrated for the first time that the FAP.291 minigene vaccine could induce mouse CTLs and also function as a tumor regression antigen, providing the basis for future studies of FAPα epitope-based vaccines. This study may also be valuable for further improvement of the immunogenicity of analogue epitope vaccines.

Experimental Study of Potential CD8+ Trivalent Synthetic Peptides for Liver Cancer Vaccine Development Using Sprague Dawley Rat Models

Background. Liver cancer (LC) is the most devastating disease affecting a large set of populations in the world. The mortality due to LC is escalating, indicating the lack of effective therapeutic options. Immunotherapeutic agents may play an important role against cancer cells. As immune cells, especially T lymphocytes, which are part of cancer immunology, the design of vaccine candidates for cytotoxic T lymphocytes may be an effective strategy for curing liver cancer. Results. In our study, based on an immunoinformatics approach, we predicted potential T cell epitopes of MHC class I molecules using integrated steps of data retrieval, screening of antigenic proteins, functional analysis, peptide synthesis, and experimental in vivo investigations. We predicted the binding affinity of epitopes LLECADDRADLAKY, VSEHRIQDKDGLFY, and EYILSLEELVNGMY of LC membrane-bounded extracellular proteins including butyrophilin-like protein-2 (BTNL2), glypican-3 (GPC3), and serum albumin (ALB), respectively, with MHC class I molecules (allele: HLA-A $\ast$ 01:01). These T cell epitopes rely on the level of their binding energy and antigenic properties. We designed and constructed a trivalent immunogenic model by conjugating these epitopes with linkers to activate cytotoxic T cells. For validation, the nonspecific hematological assays showed a significant rise in the count of white blood cells ( $5\times {10}^9/\text{l}$ ), lymphocytes ( $13\times {10}^9/\text{l}$ ), and granulocytes ( $5\times {10}^9/\text{l}$ ) compared to the control after administration of trivalent peptides. Specific immunoassays including granzyme B and IgG ELISA exhibited the significant concentration of these effector molecules in blood serum, indicating the activity of cytotoxic T cells. Granzyme concentration increased to 1050 pg/ml at the second booster dose compared to the control (95 pg/ml), while the concentration of IgG raised to 6 g/l compared to the control (2 g/l). Conclusion. We concluded that a potential therapeutic trivalent vaccine can activate and modulate the immune system to cure liver cancer on the basis of significant outcomes of specific and nonspecific assays.