Apart from its role as a digestive and absorptive organ, the gastrointestinal (GI) tract is a vital immune organ that encompasses roughly 70 % of the total immune cells of the body. As such, the physical, chemical and nutrient composition of the diet influences overall GI function, effectively as an immune organ. With the improvement in feed technology, agro-industrial co-products that are high in fibre have been widely used as a feed ingredient in the diets of pigs and poultry. Arabinoxylan (AX) and mannan are the most abundant hemicellulosic polysaccharides present in cereal grain and co-product ingredients used in the livestock industry. When monogastric animals consume diets containing high amounts of AX and mannans, stimulation of GI immune cells may occur. This involves the activation of several cellular and molecular pathways of the immune system and requires a considerable amount of energy and nutrients to be expended by the animal, which may ultimately influence overall health and growth performance of animals. Therefore, a better understanding of the role of AX and mannan in immune modulation will be helpful in modulating untoward GI immune responses, thereby minimising nutrient and energy expenditure toward this effort. This review will summarise pertinent research on the role of oligosaccharides and polysaccharides containing AX and mannans in immune modulation in order to preserve gut integrity.

Several studies have evaluated the association between mannose-binding lectin (MBL) polymorphisms and sepsis. However, the results are inconclusive and conflicting. To better understand the roles of MBL polymorphisms in sepsis, we conducted a comprehensive meta-analysis. All relevant studies were searched from PubMed, EMBASE and Web of Knowledge databases, with the last report up to 7 May 2013. Twenty-nine studies addressing four MBL polymorphisms (–550G/C, –221G/C, structure variant A/O, Gly54Asp) were analysed for susceptibility to sepsis and one study for sepsis-related mortality. Overall, significant associations between structure variant A/O and susceptibility to sepsis were observed for AO + OO vs. AA [odds ratio (OR) 1·27, 95% confidence interval (CI) 1·05–1·52, P = 0·01] and O vs. A (OR 1·19, 95% CI 1·02–1·40, P = 0·03). In subgroup analysis based on age group, increased risk was found in the paediatric group in the dominant model (OR 1·72, 95% CI 1·16–2·56, P = 0·007). Moreover, there was a slight association between the +54A/B polymorphism and susceptibility to sepsis in Caucasians (recessive model: OR 10·64, 95% CI 1·24–91·65, P = 0·03). However, no association was observed for –550G/C and –221G/C polymorphisms both overall and in subgroup analysis. For sepsis-related mortality, only one study suggested AO/OO was associated with in-hospital mortality in pneumococcal sepsis patients after controlling for confounding variables. Our meta-analysis indicated that MBL structure variants might be associated with susceptibility to sepsis but further studies with a large sample size should be conducted to confirm these findings.