Abstract
Polysaccharides from red algae Porphyra haitanensis and Gracilaria lemaneiformis possess various bioactive functions, however, their anti-diarrhea activity remains incompletely defined. In the current study, sulphated polysaccharides were extracted by high pressure treatment plus ethanol precipitation from these two algae, and named PHSP(hp) and GLSP(hp), respectively. PHSP(hp) and GLSP(hp) showed decreased viscosity and molecular weight. Meanwhile, they have a certain immunomodulatory effect on wound healing and migration of RAW264.7 cells. Moreover, they significantly increased the secretion of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). A BALB/c model infected by enterotoxigenic Escherichia coli (ETEC)-K88 was also established to evaluate the anti-diarrhea activity of PHSP(hp) and GLSP(hp). The results showed that PHSP(hp) and GLSP(hp) were able to alleviate mice diarrhea symptoms. Meanwhile, they inhibited the release of pro-inflammatory cytokines and suppressed the secretion of immunoglobulin A via reducing the population of B cells. In addition, the nitroblue tetrazolium levels of mouse serum were decreased. Taken together, PHSP(hp) and GLSP(hp) alleviated the inflammatory response of ETEC-K88-induced diarrhea through both specific and non-specific immunity. Sulphated polysaccharides from red algae may be used as functional food components for remitting diarrhea.
Highlights
Diarrhea is a digestive disorder disease generally characterized by abnormally frequent defaecation, and/or blood and poorly fecal matter in feces, as well as electrolyte imbalance.[1]
Nowadays its mortality rate has been reduced due to improved medical care, it still remained the second leading lethal cause for children under age ve, in the developing countries, as reported in 2012.3,4 Among various types of infectious diarrhea, bacterial infection can cause a cute diarrhea which is characterized by fever, vomiting, abdominal pain, nausea and anorexia.[5]
This study aims to investigate the immunomodulatory and anti-diarrhea activity of sulphated polysaccharides isolated from P. haitanensis and G. lemaneiformis in RAW264.7 cells and a mouse model with enterotoxigenic Escherichia coli (ETEC)-K88-induced diarrhea
Summary
Diarrhea is a digestive disorder disease generally characterized by abnormally frequent defaecation (three times or more per day), and/or blood and poorly fecal matter in feces, as well as electrolyte imbalance.[1] According to epidemiological analysis, diarrhea is one of the most common diseases with global incidence greater than one billion per year.[2] nowadays its mortality rate has been reduced due to improved medical care, it still remained the second leading lethal cause for children under age ve, in the developing countries, as reported in 2012.3,4 Among various types of infectious diarrhea, bacterial infection can cause a cute diarrhea which is characterized by fever, vomiting, abdominal pain, nausea and anorexia.[5] The most common bacterial dysentery pathogens include Escherichia coli, Salmonella, Shigella and Staphylococcus aureus.[6] Some strains of E. coli cause infections in the gastrointestinal tract system, while others may lead to non-gastrointestinal infections such as bacteremia, hospital pneumonia and neonatal meningitis.[7]. The enterotoxigenic Escherichia coli (ETEC) expresses one or more mbrial adhesins, including F4 (K88), F5 (K99), F6 (987P), F7 (F41) and F18, that tightly bind to glycoprotein receptors on the enterocyte brush border to enable bacteria colonization in the small intestine. The bacteria secrete heat-labile enterotoxins and/or heat-stable enterotoxins that alter the tight junction integrity and disrupt the paracellular passages of ions, solutes and water, leading to diarrhea.[8,9,10]
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