Abstract
The use of solar irradiation to sterilize water prior to its consumption has resulted in the reduction of water related illnesses in waterborne disease endemic communities worldwide. Currently, research on solar water disinfection (SODIS) has been directed towards understanding the underlying mechanisms through which solar irradiation inactivates the culturability of microorganisms in water, enhancement of the disinfection process, and the health impact of SODIS water consumption. However, the immunological consequences of SODIS water consumption have not been explored. In this study, we investigated the effect that solar irradiated V. cholerae may have had on the secretion of cytokines and chemokines by the JAWS II dendritic cell line in vitro. The JAWS II dendritic cell line was stimulated with the different strains of V. cholerae that had been: (i) prepared in PBS, (ii) inactivated through a combination of heat and chemical, (iii) solar irradiated, and (iv) non-solar irradiated, in bottled water. As controls, LPS (1 μg/ml) and CTB (1 μg/ml) were used as stimulants. After 48 hours of stimulation the tissue culture media from each treatment was qualitatively and quantitatively analysed for the presence of IL-1α, IL-1β, IL-6, IL-7, IL-10, IL-12p40, IL-12p70, IL-15, MIP-1α, MIP-1β, MIP-2, RANTES, TNF-α, IL-23 and IL-27. Results showed that solar irradiated cultures of V. cholerae induced dendritic cells to secrete significant (p<0.05) levels of pro-inflammatory cytokines in comparison to the unstimulated dendritic cells. Furthermore, the amount of pro-inflammatory cytokines secreted by the dendritic cells in response to solar irradiated cultures of V. cholerae was not as high as observed in treatments involving non-solar irradiated cultures of V. cholerae or LPS. Our results suggest that solar irradiated microorganisms are capable of inducing the secretion of pro-inflammatory cytokines and chemokines. This novel finding is key towards understanding the possible immunological consequences of consuming SODIS treated water.
Highlights
The diseases associated with the consumption of microbiologically contaminated water remains a major global challenge
Iscove’s Modified Dulbecco’s Medium (IMDM), and sterile 1x Phosphate Buffer Saline (PBS) were purchased from Life technologies (Carlsbad, CA); antibiotics penicillin and streptomycin were purchased from BioWhittaker (Walkersville, MD) whereas gentamicin was purchased from Melford (Chelsworth, United Kingdom); Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) was purchased from Abcam (Cambridge, United Kingdom); Fetal Bovine Serum (FBS) was purchased from Thermo scientific (Waltham, MA); the rough form lipopolysaccharide (LPS) from E. coli serotype J5 and the cholera toxin beta-subunit (CTB) were purchased from ENZO Life Sciences (Farmingdale, NY); 2-mercaptoethanol (2-ME) and 0.25% Trypsin-0.02% EDTA were purchased from Sigma
Solar irradiated cultures of V. cholerae induced the expression of IL-6 but it was not as high as that observed when non-solar irradiated cultures of V. cholerae, LPS and CTB were used as stimulants
Summary
The diseases associated with the consumption of microbiologically contaminated water remains a major global challenge. This is often attributed to poor hygiene and sanitary practices as well as the lack of basic sanitary infrastructure. Cholera is a life threatening water borne infection that continues to claim more than 100,000 lives annually [4] This disease results from infection with pathogenic members of the species of a motile Gram-negative bacterium called Vibrio cholerae. The spread of water borne diseases such as cholera could be mitigated through the implementation of preventative measures [6] These include but are not limited to the provision of basic sanitary infrastructure, treated piped water and proper hygiene and sanitation campaigns. SODIS of water could be regarded as an ideal intervention because it is easy to use, sustainable and compatible to the life style encountered in resource poor communities [6]
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