Production of recombinant immunotherapeutics for anticancer treatment: the role of bioengineering.

Cancer is one of the most important health problems because many cases are difficult to prevent. Cancer still has unknown mechanisms of pathogenesis, and its capacity to produce temporary or permanent damage, besides death, is very high. Although many anticancer therapies are available, finding a cure for cancer continues to be a difficult task. Thus, many efforts have been made to develop more effective treatments, such as immunotherapy based on a new class of tumor-specific products that are produced using recombinant DNA technology. These recombinant products are used with the main objectives of killing the tumor and stimulating immune cells to respond to the cancer cells. The principal recombinant products in anticancer therapy are immunostimulants, vaccines, antibodies, immunotoxins and fusion proteins. This review focuses on the general aspects of these genetically engineered products, their clinical performance, current advances and future prospects for this type of anticancer therapy.

CD8+ T cell adjuvant effects of Salmonella FliCd flagellin in live vaccine vectors or as purified protein.

Salmonella flagellin, the flagellum structural subunit, has received particular interest as a vaccine adjuvant conferring enhanced immunogenity to soluble proteins or peptides, both for activation of antibody and cellular immune responses. In the present study, we evaluated the Salmonella enterica FliCd flagellin as a T cell vaccine adjuvant using as model the 9-mer (SYVPSAEQI) synthetic H2(d)-restricted CD8(+) T cell-specific epitope (CS(280-288)) derived from the Plasmodium yoelii circumsporozoite (CS) protein. The FliCd adjuvant effects were determined under two different conditions: (i) as recombinant flagella, expressed by orally delivered live S. Dublin vaccine strains expressing the target CS(280-288) peptide fused at the central hypervariable domain, and (ii) as purified protein in acellular vaccines in which flagellin was administered to mice either as a recombinant protein fused or admixed with the target CS(280-288) peptide. The results showed that CS(280-288)-specific cytotoxic CD8(+) T cells were primed when BALB/c mice were orally inoculated with the expressing the CS(280-288) epitope S. Dublin vaccine strain. In contrast, mice immunized with purified FliCd admixed with the CS(280-288) peptide and, to a lesser extent, fused with the target peptide developed specific cytotoxic CD8(+) T cell responses without the need of a heterologous booster immunization. The CD8(+) T cell adjuvant effects of flagellin, either fused or not with the target peptide, correlated with the in vivo activation of CD11c(+) dendritic cells. Taken together, the present results demonstrate that Salmonella flagellins are flexible adjuvant and induce adaptative immune responses when administered by different routes or vaccine formulations.

Leukotrienes are potent adjuvant during fungal infection: effects on memory T cells.

Leukotrienes (LTs) are potent lipid mediators involved in the control of host defense. LTB(4) induces leukocyte accumulation, enhances phagocytosis and bacterial clearance, and increases NO synthesis. LTB(4) is also important in early effector T cell recruitment that is mediated by LTB(4) receptor 1, the high-affinity receptor for LTB(4). The aims of this study were to evaluate whether LTs are involved in the secondary immune response to vaccination in a murine model of Histoplasma capsulatum infection. Our results demonstrate that protection of wild-type mice immunized with cell-free Ags from H. capsulatum against histoplasmosis was associated with increased LTB(4) and IFN-gamma production as well as recruitment of memory T cells into the lungs. In contrast, cell-free Ag-immunized mice lacking 5-lipoxygenase(-/-), a critical enzyme involved in LT synthesis, displayed a marked decrease on recruitment of memory T cells to the lungs associated with increased synthesis of TGF-beta as well as IL-10. Strikingly, these effects were associated with increased mortality to 5-lipoxygenase(-/-)-infected mice. These data establish an important immunomodulatory role of LTs, in both the primary and secondary immune responses to histoplasmosis.

Hydrogen sulfide augments neutrophil migration through enhancement of adhesion molecule expression and prevention of CXCR2 internalization: role of ATP-sensitive potassium channels.

In this study, we have addressed the role of H(2)S in modulating neutrophil migration in either innate (LPS-challenged naive mice) or adaptive (methylated BSA (mBSA)-challenged immunized mice) immune responses. Treatment of mice with H(2)S synthesis inhibitors, dl-propargylglycine (PAG) or beta-cyanoalanine, reduced neutrophil migration induced by LPS or methylated BSA (mBSA) into the peritoneal cavity and by mBSA into the femur/tibial joint of immunized mice. This effect was associated with decreased leukocyte rolling, adhesion, and P-selectin and ICAM-1 expression on endothelium. Predictably, treatment of animals with the H(2)S donors, NaHS or Lawesson's reagent, enhanced these parameters. Moreover, the NaHS enhancement of neutrophil migration was not observed in ICAM-1-deficient mice. Neither PAG nor NaHS treatment changed LPS-induced CD18 expression on neutrophils, nor did the LPS- and mBSA-induced release of neutrophil chemoattractant mediators TNF-alpha, keratinocyte-derived chemokine, and LTB(4). Furthermore, in vitro MIP-2-induced neutrophil chemotaxis was inhibited by PAG and enhanced by NaHS treatments. Accordingly, MIP-2-induced CXCR2 internalization was enhanced by PAG and inhibited by NaHS treatments. Moreover, NaHS prevented MIP-2-induced CXCR2 desensitization. The PAG and NaHS effects correlated, respectively, with the enhancement and inhibition of MIP-2-induced G protein-coupled receptor kinase 2 expression. The effects of NaHS on neutrophil migration both in vivo and in vitro, together with CXCR2 internalization and G protein-coupled receptor kinase 2 expression were prevented by the ATP-sensitive potassium (K(ATP)(+)) channel blocker, glybenclamide. Conversely, diazoxide, a K(ATP)(+) channel opener, increased neutrophil migration in vivo. Together, our data suggest that during the inflammatory response, H(2)S augments neutrophil adhesion and locomotion, by a mechanism dependent on K(ATP)(+) channels.

Effect of various microbial preparations on P-388 mouse lymphocytic leukemia.

Four bacteria-derived immunopotentiators were tested for their protective effect on a P-388 mouse lymphocytic leukemia model. The microbial test products were prepared from the following bacterial strains: ATCC 35983 Staphylococcus epidermidis isolated from a patient with IV catheter; ATCC 31874, a patented strain listed as Staphylococcus epidermidis isolated from the urine of a cancer patient; ATCC 25615 Staphylococcus hominis obtained from a child with lymphocytic leukemia, and ATCC 25614 Staphylococcus warneri, an isolate from a patient with adenocarcinoma of the breast. A limited degree of protection and prolongation in survival time was observed in the animal group treated with the bacterial strain ATCC 31874.

Effect of various microbial preparations on P-388 mouse lymphocytic leukemia

Four bacteria-derived immunopotentiators were tested for their protective effect on a P-388 mouse lymphocytic leukemia model. The microbial test products were prepared from the following bacterial strains: ATCC 35983 Staphylococcus epidermidis isolated from a patient with IV catheter; ATCC 31874, a patented strain listed as Staphylococcus epidermidis isolated from the urine of a cancer patient; ATCC 25615 Staphylococcus hominis obtained from a child with lymphocytic leukemia, and ATCC 25614 Staphylococcus warneri, an isolate from a patient with adenocarcinoma of the breast. A limited degree of protection and prolongation in survival time was observed in the animal group treated with the bacterial strain ATCC 31874

[Adjuvant activity of lactic bacteria: perspectives for its use in oral vaccines]. / Actividad adyuvante de bacterias lácticas: perspectivas para su uso en vacunas orales.

The effect of the oral and subcutaneous administration of Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophilus on humoral antibody production and delayed type hypersensitivity response against sheep red blood cells (SRBC) was studied. The species of the genus Lactobacillus proved to be more effective in both cases, effects being stronger when working with viable bacteria than with non-viable cells. The stimulation of primary cellular and humoral immune responses reached optimal activity with a dose of 6 x 10(9) cells. The plaque-forming cells (PFC) and the circulating antibody titers to the SRBC antigen obtained in the groups treated with lactobacilli were 2 to 3 times higher than those of the non-treated control group. In mice fed with the different lactic acid bacteria circulating antibody against these microorganisms failed to be detected, but when they were administered by subcutaneous route a strong response to antilactic acid bacteria was stimulated. S. thermophilus was not effective in increasing the immune response. These results suggest that the lactobacilli by oral route, exert a strong adjuvant activity which is responsible for the enhanced host immune responses obtained. In this respect, lactobacilli could be considered as the most promising oral adjuvant.

Actividad adyuvante de bacterias lácticas: perspectivas para su uso en vacunas orales / Adjuvant activity of lactic bacteria: perspectives for its use in oral vaccines

Se estudió el efecto de la administración oral y subcutánea de Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus bulgaricus y Streptococcus thermophilus, sobre la respuesta inmune humoral e hipersensibilidad retardada para el antígeno glóbulo rojo de carnero (GRC). Las especies del género Lactobacillus fueron más efectivas en ambas respuestas, siendo mayor el efecto cuando las bacterias eran viables. La dosis óptima efectiva fue de 6 x 10**9 células. El número de células formadoras de placas (PFC) el título de anticuerpo circulante para el antígeno GRC fue de 2 a 3 veces mayor que los obtenidos en el grupo control. En los ratones alimentados con bacterias lácticas no se detectaron anticuerpos contra sus propios epitopes, pero sí se obtuvieron altos niveles de anticuerpos anti-bacterias lácticas en aquellos animales que habían sido inoculados subcutáneamente con estas bacterias. S. thermophilu no incrementó la respuesta inmune. Los resultados indican que los lactobacilos administrados por vía oral, ejercen una fuerte actividad adyuvante, responsable del aumento de la respuesta imune del húsped. Dichos organismso podrían ser candidatos a ser empleados como adyuvante en vacunas orales

Actividad adyuvante de bacterias lácticas: perspectivas para su uso en vacunas orales / Adjuvant activity of lactic bacteria: perspectives for its use in oral vaccines

Se estudió el efecto de la administración oral y subcutánea de Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus bulgaricus y Streptococcus thermophilus, sobre la respuesta inmune humoral e hipersensibilidad retardada para el antígeno glóbulo rojo de carnero (GRC). Las especies del género Lactobacillus fueron más efectivas en ambas respuestas, siendo mayor el efecto cuando las bacterias eran viables. La dosis óptima efectiva fue de 6 x 10**9 células. El número de células formadoras de placas (PFC) el título de anticuerpo circulante para el antígeno GRC fue de 2 a 3 veces mayor que los obtenidos en el grupo control. En los ratones alimentados con bacterias lácticas no se detectaron anticuerpos contra sus propios epitopes, pero sí se obtuvieron altos niveles de anticuerpos anti-bacterias lácticas en aquellos animales que habían sido inoculados subcutáneamente con estas bacterias. S. thermophilu no incrementó la respuesta inmune. Los resultados indican que los lactobacilos administrados por vía oral, ejercen una fuerte actividad adyuvante, responsable del aumento de la respuesta imune del húsped. Dichos organismso podrían ser candidatos a ser empleados como adyuvante en vacunas orales (AU)