El cáncer de mama es el cáncer más común en las mujeres de México y en el mundo. Múltiples investigaciones se han centrado en buscar nuevas alternativas para el tratamiento de esta neoplasia, incluyendo el estudio de productos naturales. El propóleos, una resina elaborada por las abejas, tiene una composición química muy variada, que depende de las fuentes botánicas disponibles en la zona geográfica y estación del año de recolección. Su acción antiproliferativa se debe principalmente a la inducción de apoptosis y arresto del ciclo celular. Este artículo ofrece una visión general del cáncer de mama y sus clasificaciones, examina la importancia del ciclo celular y sus diferentes fases, y aborda la complejidad química del propóleos y su actividad biológica. Por último, detalla los mecanismos intracelulares responsables del efecto antiproliferativo del propóleos en el cáncer de mama, con particular énfasis en su capacidad para detener el ciclo celular.

Aims Giardia lambliais a protozoan parasite that causes giardiasis, one of the most common worldwide gastrointestinal diseases. For rational development of aGiardiavaccine, increasing our understanding of the host-Giardiainteraction is crucial. In this study, we analysed the immunogenicity and antigenicity of twoG lambliastrain variants [GS and GS-5G8 (+)], which express different levels of the variant-specific surface protein (VSP) 5G8 and also analysed the intestinal histological changes associated withGiardiainfection. Methods and results We evaluated the antibody responses induced byG lambliastrains in infected, reinfected and immunized C3H/HeJ mice using ELISA, flow cytometry, Western blotting and histological analysis. Our results showed thatG lambliaGS-5G8 (+) was more immunogenic and antigenic than the GS strain. The antibody response against the GS-5G8 (+) strain primarily recognized 5G8 protein. Serum antibody from infected and reinfected mice exhibited specific agglutination of trophozoites in vitro. GS-5G8 (+)-infected mice showed higher CD19(+)infiltrating cell levels compared to GS-infected animals. Conclusion G lambliastrains with different expression levels of an immunogenic antigen (VSP 5G8) induce differential antibody responses. A better understanding of the immunogenic proteins ofG lambliawill contribute to the rational development of an effective vaccine against this parasitic disease.

Giardiasis is one of the most common gastrointestinal diseases worldwide, caused by the protozoan parasite Giardia lamblia. Although several immunogenic proteins of the parasite have been identified, the capacity of inducing a protective humoral response has been scarcely evaluated. Our research group have identified and characterized the immunogenic 5G8 protein, a 70 kDa Variant‐specific surface protein (VSP). The administration of 5G8‐specific monoclonal antibodies (AcMo 5G8.B5) to infected animal decreased the parasite intestinal load. The aim of the present study was to evaluate the in vitro effect of 5G8 specific antibodies on G. lamblia trophozoites. We isolated 5G8 protein by passive elution from SDS‐PAGE (membrane protein enriched fraction of trophozoites lysates). C3H/HeJ mice were intraperitoneally immunized with isolated 5G8 protein to generate polyclonal antibodies. GS/M‐83‐H7 5G8 (+) trophozoites were incubated with monoclonal and polyclonal antibodies specific to the 5G8 protein, and their agglutination capacity was evaluated. After 24, 48 and 72 hours incubation, cell proliferation was determinated and the expression of 5G8 protein on trophozoites was evaluated by Flow Cytometry. Polyclonal antibodies recognized 97 % of GS/M‐83‐H7 5G8 (+) trophozoite population, and a single band of 70 kDa (SDS‐PAGE). The AcMo 5G8.B5 and polyclonal antibodies had the ability to agglutinate G. lamblia trophozoites in vitro after 60 min of antibody exposure. Antibody treatments inhibited the in vitro G. lamblia growth. Isotype control antibody and preimmunized serum showed no inhibition of trophozoites proliferation. Surface 5G8 protein expression did not change during antibody treatments. Altogether, our data suggest a possible in vitro cytostatic effect of 5G8 specific antibodies on G. lamblia trophozoites. These findings put forward the capacity of the 5G8 protein to induce a protective humoral response against the infection.Support or Funding InformationCONACYT: CB‐2010‐01/155224This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Giardia lamblia is a protozoan parasite that causes one of the most common gastrointestinal diseases worldwide. To eliminate the parasite from the host intestine, it is necessary the activation of B-cell and T-cell dependent mechanisms. The knowledge about Giardia antigens that can stimulate the host immune response is limited. Recently, it has been described the Binding Immunoglobulin Protein (BIP) of G. lamblia (71kDa) as a potential immunogen. Additionally, our group has identified a highly immunogenic antigen (5G8 protein) of G. lamblia with a relative molecular mass of approximately 70kDa. There is some evidence suggesting that the 5G8 protein may activate both humoral and cellular immune responses. Based on these observations and preliminary mass spectrometry analyses, we hypothesized that the antigen 5G8 could be the BIP protein. In the present study, we characterize immunochemically the BIP protein of Giardia. Flow cytometric assays and western blotting were used to determine the expression profile of BIP and 5G8 antigens in Giardia trophozoites. The differences in expression profile indicated that BIP and 5G8 are not the same molecule. ELISA and Western blotting assays revealed that BIP protein was recognized by antibodies produced during G. lamblia infection in C3H/HeN mice. MTT assays did not reveal the activation of cellular immune response induced by BIP protein in vitro. In addition, we identified the potential B-cell and T-cell epitopes of G. lamblia BIP protein. This molecule is a conserved protein among Giardia strains and other pathogens. The complete immunological characterization of this antigen will contribute to a better understanding of the host–parasite interactions in Giardia infection.

Humoral and cellular immune responses play an important role during Giardia lamblia infection. Several Giardia proteins have been identified as immunogenic antigens based on their elicited humoral immune response. Poorly is known about Giardia antigens that stimulate a cellular immune response. The main purpose of this study was to isolate and partial characterize an immunogenic antigen (5G8) of G. lamblia. The 5G8 protein was isolated from G. lamblia trophozoite lysates by affinity chromatography using moAb 5G8-coupled CNBr-Sepharose. The isolated protein was analysed by electrospray tandem mass spectrometry (ESI-MS/MS), and by diverse bioinformatics tools (GiardiaDB, BLASTn, BLASTp and ExPASy). Additionally, several biochemical and immunological characteristics of the isolated protein were analysed. By ESI-MS/MS the amino acidic 5G8 sequence was deduced. The 5G8 antigen belongs to the VSP family proteins of G. lamblia. This protein is composed by one polypeptide chain (±71kDa). Using the algorithm SYFPHEITI, we identified candidate CD4+ T-cell epitopes from the 5G8 antigen, which can elicit cell-mediated immune responses. In this study, we have identified a G. lamblia protein that induces a strong immune response in infected mice. The biochemical and immunological characterization of the immunogenic 5G8 antigen may contribute to the rational design of a Giardia vaccine.

Abstract The protozoan parasite G. lamblia is an intestinal parasite of humans, which the World Health Organization estimates to have infected 250 million people worldwide. Clinical manifestations of G. lamblia infections vary from the asymptomatic carrier state to severe diarrhea, abdominal pain, nausea, malabsorption and weight loss. Our knowledge about the immunogenic antigens of G. lamblia is limited. The purpose of this study was immunologically and biochemically characterize an immunogenic antigen (protein 5G8) of G. lamblia. We generated monoclonal antibodies (moAbs) spe­cific to the protein 5g8 of the parasite by using splenocytes derived from in­fected mice. All of these moAbs recognized a protein of 71 kDa by Western blotting. This protein was isolated from a G. lamblia trophozoite lysate by affinity chromatography. The purified 71 kDa protein was analyzed by mass spectrometry. This immunogenic antigen was expressed inside of the G.lamblia trofozoites (>90% of total cell population) and only a small percentage (≈ 2-5%) of those trophozoites expressed high levels of the 5G8 protein on the cell surface. Trophozoite population expressing the 5G8 protein on the cell surface induced stronger antibody response that trophozoite population that does not express this protein on cell surface. The characterization of this antigen will provide a better understanding of the G. lamblia-host interaction, and will be important for developing effective control strategies against giardiasis.

Abstract Propolis is a cereus resin with a complex chemical composition that possesses a wide range of biological activities. The aim of this study was to evaluate the in vitro anti-Giardia lamblia activity of Sonoran propolis collected from three different areas of Sonoran Desert in northwestern Mexico (Caborca, Pueblo de Alamos, and Ures) and some of its chemical constituents. Additionally, we also analyzed the seasonal effect on the anti-G. lamblia activity of propolis. G. lamblia trophozoite cultures were treated with different concentrations of Sonoran propolis or chemical compounds during 48 h cell proliferation and cell viability were determined. Ures propolis showed the highest inhibitory activity against G. lamblia (IC50 63.8 ± 7.1 µg/mL) in a dose-dependent manner (Ures > Pueblo de Alamos > Caborca). Season had a significant effect on the in vitro anti-G. lamblia activity of Ures propolis. Summer propolis showed the highest inhibitory effect on the G. lamblia trophozoite growth (IC50 23.8 ± 2.3 µg/mL), followed by propolis collected during winter (IC50 59.2 ± 34.7 µg/mL), spring (IC50 102.5 ± 15.3 µg/mL), and autumn (IC50 125.0 ± 3.1 µg/mL). Caffeic acid phenethyl ester, an Ures propolis exclusive constituent, had the highest growth-inhibitory activity towards G. lamblia [IC50 63.1 ± 0.9 µg/mL (222.1 ± 3.2 µM)]. To our knowledge, this is the first study showing that caffeic acid phenethyl ester possesses antiparasitic activity against G. lamblia. Naringenin [IC50 125.7 ± 20.7 µg/mL (461.8 ± 76.3 µM)], hesperetin [IC50 149.6 ± 24.8 µg/mL (494.9 ± 82.2 µM)], and pinocembrin [IC50 174.4 ± 26.0 µg/mL (680.6 ± 101.7 µM)] showed weak anti-G. lamblia activity. On the other hand, chrysin and rutin did not show significant antiparasitic activity. In conclusion, our results suggest that Sonoran propolis and some of its chemical constituents had inhibitory effects on the in vitro growth of G. lamblia trophozoites.

The humoral immune response plays an important role in the clearance of Giardia lamblia. However, our knowledge about the specific antigens of G. lamblia that induce a protective immune response is limited. The purpose of this study was to identify and characterise the immunogenic proteins of G. lamblia in a mouse model. We generated monoclonal antibodies (moAbs) specific to G. lamblia (1B10, 2C9.D11, 3C10.E5, 3D10, 5G8.B5, 5F4, 4C7, 3C5 and 3C6) by fusing splenocytes derived from infected mice. Most of these moAbs recognised a band of ± 71 kDa (5G8 protein) and this protein was also recognised by serum from the infected mice. We found that the moAbs recognised conformational epitopes of the 5G8 protein and that this antigen is expressed on the cell surface and inside trophozoites. Additionally, antibodies specific to the 5G8 protein induced strong agglutination (> 70-90%) of trophozoites. We have thus identified a highly immunogenic antigen of G. lamblia that is recognised by the immune system of infected mice. In summary, this study describes the identification and partial characterisation of an immunogenic protein of G. lamblia. Additionally, we generated a panel of moAbs specific for this protein that will be useful for the biochemical and immunological characterisation of this immunologically interesting Giardia molecule.