Investigating the intracellular growth, cytotoxicity and apoptotic effects of solar irradiated Campylobacter jejuni in a murine macrophage cell line (RAW 264.7)

Campylobacter jejuni is a leading cause of gastroenteritis worldwide. Solar disinfected (SODIS) water can reduce diarrhoeal incidences in communities where potable water is inaccessible. SODIS water has been associated with the reduction of diarrhoeal incidences amongst SODIS users. Thus solar attenuation of bacteria may have a significant impact on immune cells such as macrophages. When solar irradiated cells die the release antigenic materials such lipopolysaccharides and intracellular contents into the water. The solar irradiated bacterial may have an impact on the cytotoxicity and cell death of immune cells such as macrophages. This study assessed the effects of solar irradiation on the viability, metabolic activity and three virulence characteristics (invasion, cytotoxicity, and apoptosis) of C. jejuni on RAW 264.7 cells. Samples of C. jejuni were suspended in water and treated in the following ways (i) heat and chemically attenuated (1% formalin at 60°C for one hour), (ii)) exposure to solar ultraviolet radiation (SUVR) for 0, 4 and 8 and, (iii) non-exposure to SUVR. The metabolic activity was assayed spectrophotometrically using Alamar Blue. The C. jejuni samples were used to infect macrophage RAW264.7 cells and its intracellular growth was assessed by using the gentamicin protection assay. Cytotoxicity was assessed by using the Lactate Dehydrogenase Assay (LDH). Apoptosis of the treated macrophages was analysed by Flow Cytometry. The results showed that all the C. jejuni were not culturable. However, the non-solar irradiated Campylobacter jejuni retained its metabolic activity (40.2%±1%) whereas no metabolic activity was observed in the heat and chemically attenuated and solar irradiated bacteria. Intracellular growth of the bacteria in the RAW264.7 cells was not detected in all the treated samples. The non-irradiated C. jejuni showed higher cytotoxic and apoptotic effects on macrophages than the heat attenuated and solar irradiated samples. In conclusion, solar irradiation of C. jejuni eliminates its metabolic activity and also reduces its ability to induce cytotoxicity and apoptosis in the macrophages

Assessing the cytotoxicity and apoptosis-inducing ability of solar irradiated Salmonella Typhimurium in RAW264.7 cell line in vitro

The consumption of solar disinfected (SODIS) water has reduced diarrhoeal incidences in resource-poor regions of the world. Thus, this study assessed the effects of solar radiation on the viability and on three virulence characteristics (invasion, cytotoxicity, and apoptosis) of S. Typhimurium on macrophages. Samples of S. Typhimurium were treated in three ways: (i) suspended in water and exposed to solar ultra-violet radiation (SUVR), (ii) exposed to SUVR but in a non- transparent flask, and (iii) heat and chemically attenuated by treating the bacteria with 0.5% phenol at 65°C for one hour. Salmonella Typhimurium samples were pipetted out from the three treatments after 4 and 8 h and used to infect macrophage RAW264.7 cells. The intracellular growth of S. Typhimurium was assessed by using the gentamicin protection assay. Cytotoxicity assays were carried out using the Lactate Dehydrogenase Assay (LDH). Apoptosis of infected macrophages was analysed using flow cytometry. The results showed that S. Typhimurium was inactivated after 4 and 8 h of solar irradiation. The solar irradiated S. Typhimurium exhibited no intracellular growth, and produced lower cytotoxicity and fewer necrotic cells in RAW 264.7 cells. The non-irradiated S. Typhimurium survived within the macrophages, were highly toxic to the cells and caused a significant increase (p<0.01) in necrotic cells when compared to the solar irradiated samples. In conclusion, solar irradiated S. Typhimurium impacts the viability and virulence properties especially the survival of RAW264.7 cells and also reduces their ability to induce cytotoxicity and necrotic cell death in the macrophages

Assessing the cytotoxicity and apoptosis-inducing ability of solar irradiated Salmonella Typhimurium in RAW264.7 cell line in vitro

The consumption of solar disinfected (SODIS) water has reduced diarrhoeal incidences in resource-poor regions of the world. Thus, this study assessed the effects of solar radiation on the viability and on three virulence characteristics (invasion, cytotoxicity, and apoptosis) of S. Typhimurium on macrophages. Samples of S. Typhimurium were treated in three ways: (i) suspended in water and exposed to solar ultra-violet radiation (SUVR), (ii) exposed to SUVR but in a non- transparent flask, and (iii) heat and chemically attenuated by treating the bacteria with 0.5% phenol at 65°C for one hour. Salmonella Typhimurium samples were pipetted out from the three treatments after 4 and 8 h and used to infect macrophage RAW264.7 cells. The intracellular growth of S. Typhimurium was assessed by using the gentamicin protection assay. Cytotoxicity assays were carried out using the Lactate Dehydrogenase Assay (LDH). Apoptosis of infected macrophages was analysed using flow cytometry. The results showed that S. Typhimurium was inactivated after 4 and 8 h of solar irradiation. The solar irradiated S. Typhimurium exhibited no intracellular growth, and produced lower cytotoxicity and fewer necrotic cells in RAW 264.7 cells. The non-irradiated S. Typhimurium survived within the macrophages, were highly toxic to the cells and caused a significant increase (p<0.01) in necrotic cells when compared to the solar irradiated samples. In conclusion, solar irradiated S. Typhimurium impacts the viability and virulence properties especially the survival of RAW264.7 cells and also reduces their ability to induce cytotoxicity and necrotic cell death in the macrophages

Investigating the intracellular growth, cytotoxicity and apoptotic effects of solar irradiated Campylobacter jejuni in a murine macrophage cell line (RAW 264.7)

Campylobacter jejuni is a leading cause of gastroenteritis worldwide. Solar disinfected (SODIS) water can reduce diarrhoeal incidences in communities where potable water is inaccessible. SODIS water has been associated with the reduction of diarrhoeal incidences amongst SODIS users. Thus solar attenuation of bacteria may have a significant impact on immune cells such as macrophages. When solar irradiated cells die the release antigenic materials such lipopolysaccharides and intracellular contents into the water. The solar irradiated bacterial may have an impact on the cytotoxicity and cell death of immune cells such as macrophages. This study assessed the effects of solar irradiation on the viability, metabolic activity and three virulence characteristics (invasion, cytotoxicity, and apoptosis) of C. jejuni on RAW 264.7 cells. Samples of C. jejuni were suspended in water and treated in the following ways (i) heat and chemically attenuated (1% formalin at 60°C for one hour), (ii)) exposure to solar ultraviolet radiation (SUVR) for 0, 4 and 8 and, (iii) non-exposure to SUVR. The metabolic activity was assayed spectrophotometrically using Alamar Blue. The C. jejuni samples were used to infect macrophage RAW264.7 cells and its intracellular growth was assessed by using the gentamicin protection assay. Cytotoxicity was assessed by using the Lactate Dehydrogenase Assay (LDH). Apoptosis of the treated macrophages was analysed by Flow Cytometry. The results showed that all the C. jejuni were not culturable. However, the non-solar irradiated Campylobacter jejuni retained its metabolic activity (40.2%±1%) whereas no metabolic activity was observed in the heat and chemically attenuated and solar irradiated bacteria. Intracellular growth of the bacteria in the RAW264.7 cells was not detected in all the treated samples. The non-irradiated C. jejuni showed higher cytotoxic and apoptotic effects on macrophages than the heat attenuated and solar irradiated samples. In conclusion, solar irradiation of C. jejuni eliminates its metabolic activity and also reduces its ability to induce cytotoxicity and apoptosis in the macrophages

Investigating the intracellular growth, cytotoxicity and apoptotic effects of solar irradiated Campylobacter jejuni in a murine macrophage cell line (RAW 264.7)

Campylobacter jejuni is a leading cause of gastroenteritis worldwide. Solar disinfected (SODIS) water can reduce diarrhoeal incidences in communities where potable water is inaccessible. SODIS water has been associated with the reduction of diarrhoeal incidences amongst SODIS users. Thus solar attenuation of bacteria may have a significant impact on immune cells such as macrophages. When solar irradiated cells die the release antigenic materials such lipopolysaccharides and intracellular contents into the water. The solar irradiated bacterial may have an impact on the cytotoxicity and cell death of immune cells such as macrophages. This study assessed the effects of solar irradiation on the viability, metabolic activity and three virulence characteristics (invasion, cytotoxicity, and apoptosis) of C. jejuni on RAW 264.7 cells. Samples of C. jejuni were suspended in water and treated in the following ways (i) heat and chemically attenuated (1% formalin at 60°C for one hour), (ii)) exposure to solar ultraviolet radiation (SUVR) for 0, 4 and 8 and, (iii) non-exposure to SUVR. The metabolic activity was assayed spectrophotometrically using Alamar Blue. The C. jejuni samples were used to infect macrophage RAW264.7 cells and its intracellular growth was assessed by using the gentamicin protection assay. Cytotoxicity was assessed by using the Lactate Dehydrogenase Assay (LDH). Apoptosis of the treated macrophages was analysed by Flow Cytometry. The results showed that all the C. jejuni were not culturable. However, the non-solar irradiated Campylobacter jejuni retained its metabolic activity (40.2%±1.1%) whereas no metabolic activity was observed in the heat and chemically attenuated and solar irradiated bacteria. Intracellular growth of the bacteria in the RAW264.7 cells was not detected in all the treated samples. The non-irradiated C. jejuni showed higher cytotoxic and apoptotic effects on macrophages than the heat attenuated and solar irradiated samples. In conclusion, solar irradiation of C. jejuni eliminates its metabolic activity and also reduces its ability to induce cytotoxicity and apoptosis in the macrophages