Detection of Cyclomodulin CNF-1 Toxin-Producing Strains of Escherichia coli in Pig Kidneys at a Slaughterhouse.

Food is often contaminated with Escherichia coli (E. coli) bacteria strains, which have been associated with different diseases, including urinary tract infections. The consumption of meat by humans is a potential route of transmission of antimicrobial resistance, and food-producing animals have been associated as a major reservoir of resistant bacterial strains. The aim of this study was to determine the presence of the E. coli strains producing the CNF-1 toxin in pig kidneys. Pig kidneys were collected from a Mexican slaughterhouse and classified according to their coloration into reddish kidneys (RK) and yellowish kidneys (YK). A tissue sample from each kidney was processed for histological analysis, the presence of E. coli was determined by conventional PCR assay, and the CNF-1 toxin was detected by both conventional PCR and Western blotting. Herein, an inflammatory cell infiltrate was found in all collected kidneys, regardless of macroscopic differences. Surprisingly, E. coli and the CNF-1 toxin were detected in all kidney samples. We clearly demonstrate contamination by CNF-1 toxin-producing E. coli in pork kidneys from a slaughterhouse, even in those without apparent damage. This suggests that pork may serve as a reservoir for pathogens, representing an important risk to human health.

5'UTR methylation in different genes from workers exposed to volatile organic compounds: A new insight for considering an epigenetic mark as a functional correlate.

Gene-specific methylation has been related with transcriptional/translational consequences in different cells; also, this epigenetic modification is affected by environmental exposures. In previous studies, CYP2E1 activity in toluene-exposed workers was decreased compared to controls, however, CYP2E1 promoter methylation levels did not show significant differences. Here, we compared gene-specific methylation levels at the 5'UTR region, in a subset of workers whom already participated in two former studies, compared to controls. METHODS: DNA was obtained from whole blood in five different groups: occupationally exposed to a mixture of volatile organic compounds (VOC): high levels (n = 19); low levels (n = 19) and very low levels (n = 17), toluene-exposed workers (n = 19) and control group (n = 19). We performed PCR-pyrosequencing at the 5'UTR region from four genes: CYP2E1, IL-6, SOD1 and TNF-α. RESULTS: In participants exposed to high levels of a VOC mixture, we found significant differences: lower methylation levels for IL-6, and higher methylation levels for TNF-α compared to controls. In toluene-exposed workers, we found significant, lower methylation levels for CYP2E1 compared to controls. CONCLUSION: Lower methylation levels at the 5'UTR region from CYP2E1 in toluene exposed-workers, suggests that this epigenetic modification could represent a functional correlate regarding enzymatic activity, as a response to toluene biotransformation.

The Four Horsemen in Colon Cancer.

Worldwide, neoplasms of the gastrointestinal tract have a very high incidence and mortality. Among these, colorectal cancer, which includes colon and rectum malignancies, representing both highest incidence and mortality. While gallbladder cancer, another neoplasm associated to gastrointestinal tract occurs less frequently. Genetic factors, inflammation and nutrition are important risk factors associated with colorectal cancer development. Likewise, pathogenic microorganisms inducing intestinal dysbiosis have become an important scope to determine the role of bacterial infection on tumorigenesis. Interestingly, in human biopsies of different types of gastrointestinal tract cancer, the presence of different bacterial strains, such as Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis and Salmonella enterica have been detected, and it has been considered as a high-risk factor to cancer development. Therefore, pathogens infection could contribute to neoplastic development through different mechanisms; including intestinal dysbiosis, inflammation, evasion of tumoral immune response and activation of pro-tumoral signaling pathways, such as ß catenin. Here, we have reviewed the suggested bacterial molecular mechanisms and their possible role on development and progression of gastrointestinal neoplasms, focusing mainly on colon neoplasms, where the bacteria Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis and Salmonella enterica infect.

Cancer Immunotherapy: Priming the Host Immune Response with Live Attenuated Salmonella enterica.

In recent years, cancer immunotherapy has undergone great advances because of our understanding of the immune response and the mechanisms through which tumor cells evade it. A century after the first immunotherapy attempt based on bacterial products described by William Coley, the use of live attenuated bacterial vectors has become a promising alternative in the fight against cancer. This review describes the role of live attenuated Salmonella enterica as an oncolytic and immunotherapeutic agent, due to its high affinity for tumor tissue and its ability to activate innate and adaptive antitumor immune response. Furthermore, its potential use as delivery system of tumor antigens and immunomodulatory molecules that induce tumor regression is also reviewed.

Diet-induced obese mice exhibit altered immune responses to early Salmonella Typhimurium oral infection.

Obesity is a chronic disease associated with different metabolic diseases as well as alterations in immune cell function. It is characterized by a chronic systemic low grade inflammation. There are several studies demonstrating the influence of obesity on the impaired immune response to infection. However, it is not completely clear whether the obese environment influences the development or maintenance of the immune response against infections. The aim of this study was to determine how obesity induced by a high-fat diet affects the immune response to an early oral Salmonella infection. Four groups of mice were kept in separate cages. Two of these designated as controls, fed with a normal diet; whereas other two groups were fed with a high fat diet for 10 weeks. Some mice were used for Salmonella oral infection. After 7 days of oral infection with S. Thypimurium the proportions of spleen cell subsets expressing activation markers in normal diet and HFD obese mice were stained with monoclonal antibodies and analyzed by flow cytometry. Also, mRNA levels of different cytokines were quantified by RT-PCR. It was found that obesity affects the function of the immune system against an early oral Salmonella infection, decreasing NK cells, altering the expression of activation molecules as well as cytokines mRNA levels. Interestingly, the expression some activation molecules on T lymphocytes was reestablished after Salmonella infection, but not the CD25 expression. Immune alterations could lead to immunosuppression or increased susceptibility to infections in HFD obese mice.

Bactofection of sequences encoding a Bax protein peptide chemosensitizes prostate cancer tumor cells / Bactofección de secuencias que codifican para un péptido de la proteína Bax quimiosensibiliza a células tumorales de cáncer de próstata

Abstract: Background: Tumor cell resistance to chemotherapy agents is one of the main problems in the eradication of different neoplasias. One of the mechanisms of this process is the overexpression of anti-apoptotic proteins such as Bcl-2 and Bcl-XL; blocking the activity of these proteins may contribute to the sensitization of tumor cells and allow the adequate effects of chemotherapeutic drugs. Methods and results: This study adressed the transfection of prostate cancer cells (PC3) with a plasmid encoding a recombinant protein with an antagonist peptide from the BH3 region of the Bax protein fused to the GFP reporter protein (BaxGFP). This protein induced apoptosis of these tumor cells; further, selective transport of this plasmid to the tumor cell with Salmonella enterica serovar Typhimurium (strain SL3261), a live-attenuated bacterial vector, can induce sensitization of the tumor cell to the action of drugs such as cisplatin, through a process known as bactofection. Conclusions: These results suggest that Salmonella enterica can be used as a carrier vector of nucleotide sequences encoding heterologous molecules used in antitumor therapy.

Resumen: Introducción: La resistencia a los agentes quimioterapéuticos por parte de las células tumorales es uno de los principales problemas para la erradicación de distintas neoplasias. Uno de los mecanismos involucrados en este proceso es la sobreexpresión de proteínas antiapoptóticas como Bcl-2 y Bcl-XL. El bloquear la actividad de estas proteínas puede contribuir a la sensibilización de las células tumorales, permitiendo que los fármacos quimioterapeúticos funcionen de forma adecuada. Métodos y resultados: En este trabajo se llevó a cabo la transfección de células de cáncer de próstata (PC3) por un plásmido que codifica para una proteína recombinante que contiene un péptido antagónico perteneciente a la región BH3 de la proteína Bax fusionada a la proteína reportera GFP (BaxGFP). Esta proteína fue capaz de inducir apoptosis en las células PC3. El transporte selectivo de este plásmido hacia la célula tumoral empleando Salmonella enterica serovar Typhimurium cepa SL3261, un vector bacteriano vivo atenuado, permitió la sensibilización de la célula tumoral a la acción de fármacos como el cisplatino mediante un proceso denominado bactofección. Conclusiones: Estos resultados sugieren que Salmonella enterica puede emplearse como un vector acarreador de secuencias nucleotídicas que codifican para moléculas heterólogas empleadas en la terapia antitumoral.

Bactofection of sequences encoding a Bax protein peptide chemosensitizes prostate cancer tumor cells.

BACKGROUND: Tumor cell resistance to chemotherapy agents is one of the main problems in the eradication of different neoplasias. One of the mechanisms of this process is the overexpression of anti-apoptotic proteins such as Bcl-2 and Bcl-XL; blocking the activity of these proteins may contribute to the sensitization of tumor cells and allow the adequate effects of chemotherapeutic drugs. METHODS AND RESULTS: This study adressed the transfection of prostate cancer cells (PC3) with a plasmid encoding a recombinant protein with an antagonist peptide from the BH3 region of the Bax protein fused to the GFP reporter protein (BaxGFP). This protein induced apoptosis of these tumor cells; further, selective transport of this plasmid to the tumor cell with Salmonella enterica serovar Typhimurium (strain SL3261), a live-attenuated bacterial vector, can induce sensitization of the tumor cell to the action of drugs such as cisplatin, through a process known as bactofection. CONCLUSIONS: These results suggest that Salmonella enterica can be used as a carrier vector of nucleotide sequences encoding heterologous molecules used in antitumor therapy.

[Therapeutic intervention alternatives in cancer, using attenuated live bacterial vectors: Salmonella enterica as a carrier of heterologous molecules]. / Alternativas de intervención terapéutica en cáncer usando vectores bacterianos vivos atenuados: Salmonella enterica como acarreador de moléculas heterólogas.

Salmonella enterica is a facultative anaerobic bacteria, whose ability to colonize antigen-presenting cells (APCs) such as dendritic cells and macrophages, has allowed its successful use as an alive, attenuated bacterial vector for vaccination. Salmonella enterica elicits efficient cellular, humoral and mucosal immune responses, against heterologous antigens including viruses, parasites, other bacterial species and tumor-associated antigens, since it is capable of delivering these antigens to cells of the immune system. The extracellular expression of heterologous antigens on the surface of Salmonella enterica via its type I, III and V secretion systems, and their delivery into infected cells is essential for its stimulation of immune responses against these antigens. Moreover, Salmonella enterica is a promising therapeutic agent against cancer, as demonstrated by reports of pre-clinical and clinical studies indicating that, after systemic administration, Salmonella enterica preferentially localizes in solid tumors and metastases as compared to normal tissues. In this review, we focus on novel prophylactic and therapeutic anti-cancer approaches using Salmonella enterica as a delivery system of heterologous molecules with the aim of inhibiting tumor growth.