The effect of cytokines on intestinal sugar absorption during sepsis in rabbits

Self-harm to preferentially harm the pathogens within: non-specific stressors in innate immunity

Therapies with increasing specificity against pathogens follow the immune system's evolutionary course in maximizing host defence while minimizing self-harm. Nevertheless, even completely non-specific stressors, such as reactive molecular species, heat, nutrient and oxygen deprivation, and acidity can be used to preferentially harm pathogens. Strategic use of non-specific stressors requires exploiting differences in stress vulnerability between pathogens and hosts. Two basic vulnerabilities of pathogens are: (i) the inherent vulnerability to stress of growth and replication (more immediately crucial for pathogens than for host cells) and (ii) the degree of pathogen localization, permitting the host's use of locally and regionally intense stress. Each of the various types of non-specific stressors is present during severe infections at all levels of localization: (i) ultra-locally within phagolysosomes, (ii) locally at the infected site, (iii) regionally around the infected site and (iv) systemically as part of the acute-phase response. We propose that hosts strategically use a coordinated system of non-specific stressors at local, regional and systemic levels to preferentially harm the pathogens within. With the rising concern over emergence of resistance to specific therapies, we suggest more scrutiny of strategies using less specific therapies in pathogen control. Hosts' active use of multiple non-specific stressors is likely an evolutionarily basic defence whose retention underlies and supplements the well-recognized immune defences that directly target pathogens.

Involvement of intracellular signaling in the IL-1β inhibitory effect on fructose intestinal absorption

A variety of bacteria and their excreted/secreted products having direct effects on epithelial ion transport and permeability and the release of cytokines during bacterial infection may impact directly on epithelial function. Interleukin-1β (IL-1β) is a pleiotropic cytokine that affects the intestinal absorption of nutrients. The aim of this work was to study the intracellular signaling pathways involved in the inhibitory effect of IL-1β on D-fructose intestinal transport in rabbit jejunum and Caco-2 cells. The results show that the cytokine inhibitory effect was completely reversed in presence of proteasome or PKC selective inhibitors in IL-1β treated rabbits. In addition, the activation of PI3K abolished the IL-1β effect. Likewise, these results were confirmed in Caco-2 cells. In addition, p-PI3K expression was increased by IL-1β-treatment whereas the expression of p-PKCα was not significantly affected. In summary, the results suggest that IL-1β could regulate the activation of pPKCα 73, pPI3K 55, and NF-kB proteins. These events could exert an inhibitory effect on fructose intestinal absorption by a modification of GLUT5 insertion to brush-border membrane and/or the functional transporter activity. This effect is independent of hormonal milieu and nervous stimuli.