Intestinal inflammation marker calprotectin regulates epithelial intestinal zinc metabolism and proliferation in mouse jejunal organoids.

Calprotectin (CP), a heterodimer of S100A8 and S100A9, is expressed by neutrophils and a number of innate immune cells and is used widely as a marker of inflammation, particularly intestinal inflammation. CP is a ligand for toll-like receptor 4 (TLR4) and the receptor for advanced glycation end products (RAGE). In addition, CP can act as a microbial modulatory agent via a mechanism termed nutritional immunity, depending on metal binding, most notably Zn2+. The effects on the intestinal epithelium are largely unknown. In this study we aimed to characterize the effect of calprotectin on mouse jejunal organoids as a model epithelium, focusing on Zn2+ metabolism and cell proliferation. CP addition upregulated the expression of the Zn2+ absorptive transporter Slc39a4 and of methallothionein Mt1 in a Zn2+-sensitive manner, while downregulating the expression of the Zn2+ exporter Slc30a2 and of methallothionein 2 (Mt2). These effects were greatly attenuated with a CP variant lacking the metal binding capacity. Globally, these observations indicate adaptation to low Zn2+ levels. CP had antiproliferative effects and reduced the expression of proliferative and stemness genes in jejunal organoids, effects that were largely independent of Zn2+ chelation. In addition, CP induced apoptosis modestly and modulated antimicrobial gene expression. CP had no effect on epithelial differentiation. Overall, CP exerts modulatory effects in murine jejunal organoids that are in part related to Zn2+ sequestration and partially reproduced in vivo, supporting the validity of mouse jejunal organoids as a model for mouse epithelium.

Chemotaxis of halophilic bacterium Halomonas anticariensis FP35 towards the environmental pollutants phenol and naphthalene.

Chemotaxis can play an important role in bioremediation and substrate bioavailability. The bioremediation of hydrocarbons in saline environments can be carried out by technologies using halophilic bacteria. The aim of this study is to analyse chemotactic responses of the halophilic bacterium Halomonas anticariensis FP35T to environmental pollutants, as well as its catabolic potential for biotechnological use in bioremediation processes under saline conditions. Chemotaxis was detected and quantified using a modified Adler capillary assay. PCR amplification with degenerate primers for genes encoding ring-cleaving enzymes was used to characterize the catabolic versatility of FP35T. The results indicate that phenol (100-1,000 ppm) and naphthalene (100-500 ppm) are chemoattractants for H. anticariensis FP35T in a dose-dependent manner. These hydrocarbons were observed to act as chemoattractants for FP35T grown in a wide range of sea salt solutions (5-12.5% (w/v). However, the 7.5% (w/v) saline concentration was found to have the strongest chemotactic response. We also detected genes encoding ring-cleaving enzymes in the ß-ketoadipate pathway for aromatic catabolism. These results suggest that H. anticariensis FP35T has the potential to catabolize aromatic compounds and to be used in bioremediation processes under saline conditions.