Intestinal in vitro cell culture models and their potential to study the effect of food components on intestinal inflammation

Abstract

Cell cultures are widely used in pharmaceutical, medical, food/nutrition and biological sciences. In food and nutrition science, intestinal cell culture models of human origin are attracting increasing interest but are still rarely used in investigations of the effects of bioactive food compounds on intestinal inflammation. However, such in vitro models would, among other benefits, limit the use of in vivo models and could provide new molecular data.

This review is an overview of two-dimensional (2D) and three-dimensional (3D) intestinal cell culture models and their potential use in gut inflammation studies. After describing the features of healthy and inflamed intestinal barriers, we describe the main intestinal cell lines (Caco2, HT29, T84) and their use in investigations of the transport and antioxidant/anti-inflammatory potential of some bioactive food compounds. Finally, different co-culture models of gut inflammation, in association with immune cells (PBMC, THP1 and RAW 264.7 cell lines) in both 2D and 3D models are presented. 3D models called organs-on-chips or biochips are the most recent and very promising approach made possible by bioengineering and biotechnological improvements and more accurately mimic the gut microenvironment.     

Exposure assessment of fetus and newborn to brominated flame retardants in France: preliminary data

Brominated flame retardants (BFR) are chemicals extensively used in many manufactured products to reduce the risk of fire, but also environmental pollutants. In order to assess the potential risk linked to these compounds in human, a French monitoring study was initiated to evaluate the exposure of fetus and newborn. A previously described multi-residue analytical method was used, for measuring the main classes of BFR (hexabromocyclododecane, tetrabromobisphenol-A, and tri- to deca-polybromodiphenylethers) in various biological matrices. These analyzed samples (maternal and umbilical serum, adipose tissue and breast milk) were collected on volunteer women during caesarean deliveries. Preliminary results obtained on 26 individuals (mother/newborn pairs) mainly demonstrated the presence of polybromodiphenylethers (PBDE) and tetrabromobisphenol A both in maternal and fetal matrices, and a possible risk of overexposure of newborns through breastfeeding. Contaminations levels were found globally in the ng/g lipid weight range, consistent with other published European data. Exposure results regarding highly brominated PBDE congeners (octa- to deca-BDE) appeared particularly informative and non-commonly reported, these compounds accounting for around 50% of the total PBDE load. Additional data collection and metabolism investigations are now on-going. A more complete statistical analysis related to this BFR exposition study will be provided in a next future.     

Multiscale approach of fish responses to different types of environmental contaminations: a case study

In order to study the responses of wild fish to environmental contaminations, different sites (two references and three contaminated) were sampled across the Walloon hydrographical network (southern Belgium). The status of fish communities was characterized according to an index of biotic integrity (IBI). Furthermore, population structure, reproductive parameters and biochemical assays were performed on chub (Leuciscus cephalus) as sentinel species. The results showed impaired responses in fish sampled downstream paper mill effluents (BKME), in a polychlorinated biphenyls (PCB) contaminated site, and in a river receiving pesticides (i.e. atrazine and hexachlorocyclohexane). High level of hepatic 7-ethoxyresorufin-Odeethylase (EROD) activity were evidence of direct toxicant exposure, while population structures showed unbalanced size-frequency distributions. Moreover, in the pesticide contaminated site, a higher proportion of atretic oocytes was found in females and abnormally high plasma alkali-labile phosphorus (ALP) values were noticed in males, compared to reference sites, suggesting that chubs were exposed to estrogenic compounds. IBI scores from both sites were also lower than in reference sites. On the other hand, no particular response was found in hepatic glutathione-S-transferase (GST) activities, hepatic heat-shock protein HSP70 concentrations and plasma sex steroids (estradiol-17beta, 11-ketotestosterone and testosterone) in chubs from any sites. By using a multiparametric approach, a better understanding of response mechanisms to pollution in fish may be achieved in order to improve the ecological status of river ecosystems.     

Finite element modeling of the head skeleton with a new local quantitative assessment approach

The present study was undertaken to build a finite element model of the head skeleton and to perform a new assessment approach in order to validate it. The application fields for such an improved model are injury risk prediction as well as surgical planning. The geometrical reconstruction was performed using computed tomography scans and a total of 4680 shell elements were meshed on the median surface of the head skeleton with the particular characteristic of adapted mesh density and real element thickness. The assessment protocol of the finite element model was achieved using a quasi-static experimental compression test performed on the zygomatic bone area of a defleshed isolated head. Mechanical behavior of the finite element model was compared to the real one and the assessment approach was divided into two steps. First, the mechanical properties of the anatomical structure were identified using the simulation and then the simulated displacement field was compared to local displacement measurement performed during test using a digital correlation method. The assessment showed that the head skeleton model behaved qualitatively like the real structure. Quantitatively, the local relative error varied from 8% up to 70%.     

Egg activation is the result of calcium signal summation in the mouse

Egg activation in mammals is caused by cytosolic Ca(2+) oscillations that are essential for development. However, despite increasing knowledge about signal transduction mechanisms, the functional linkage between frequency number, amplitude and duration of the Ca(2+) signal and the kinetics of pronucleus formation has not yet been defined. While a wide range of Ca(2+) signal parameters are efficient in causing egg activation, the basic rules governing how the egg integrates these signalling events are not yet clear. Thus, in the perspective of better understanding how the egg processes Ca(2+) signalling events, the objective of this study was to determine experimentally whether the efficiency of egg activation and the subsequent early developmental stages rely on Ca(2+) signalling summation. Non-fertilized, but freshly ovulated mouse eggs, were subjected to a series of repetitive Ca(2+) influxes of various patterns modulated by a non-invasive membrane electropermeabilization method. Using a combination of two suboptimal treatments we have shown that mouse eggs can sum up the effects caused by various patterns of intracellular Ca(2+) concentrations transient during the period of egg activation. In addition, overloading the intracellular milieu by repetitive Ca(2+) influxes did not seem to inhibit the process of activation. The kinetics of pronuclear formation among a population of eggs treated in the same conditions became accelerated when the total dose of Ca(2+) signal 'experienced' by the eggs was increased. The results suggested that summation of the biological effects of all Ca(2+) signals constitutes an important mode of Ca(2+) signal integration.     

Efficient fabrication of fused-fiber biconical taper structures by a scanned CO2 laser beam technique

The driving mechanism of a scanning mirror can cause significant impairment of expanded beam properties, which we investigated for several scanning waveforms. Engineering on the scanning waveform is then carried out by a scanned CO2 laser beam technique to enlarge the uniform heating region for stretching and sintering of silica fibers. Details of the derivation are given. A simple thermal model is presented to account for the relationship between the scanning beam profile and the taper shape. Fusion profiles are also compared for various scanning waveforms. The corresponding scanned beam power distributions are determined experimentally, which enables us to determine precise power density conditions for CO2 laser fusion.     

Influence of polysaccharides on oxygen dependent lactate utilization by an amylolytic Lactobacillus plantarum strain

Oxygen-dependent conversion of lactate to acetate by the amylolytic strain Lactobacillus plantarum A6 was studied using MRS-grown cells, transferred to a basic medium with lactate. In the presence of oxygen, lactate was stoechiometricaly converted to acetate. When glucose, maltose or cellobiose was added to the basic medium, no utilisation of lactate was observed. However, when starch or glycogen was added, the conversion of lactate to acetate happened. To verify the possible link of this effect with sugar consumption rate, a glucose-fed batch culture was conducted with a lactic acid consuming culture grown on the basic medium with lactate. Even when glucose was fed at the same low rate as the consumption rate observed for polysaccharides, lactic acid was no more consumed. For the amylolytic strain L. plantarum A6, the transport and use of oligosaccharides resulting from polysaccharides hydrolysis might affect differently the glycolytic flux, with the putative consequence to suppress the metabolic control of glycolysis by glucose. This fact could play an important role in the fermentation of amylaceous foods.     

Wavelet de-noising of laser Doppler reactive hyperemia signals to diagnose peripheral arterial occlusive diseases

In order to improve peripheral arterial occlusive diseases (PAOD) diagnoses, five de-noising algorithms based on a multiresolution analysis computed with wavelets are applied on reactive hyperemia signals obtained with the laser Doppler flowmetry technique. Results are presented on recordings acquired on patients suffering from PAOD and on healthy subjects.     

Systematic identification of mitochondrial proteins by LC-MS/MS

In eukaryotic cells, the mitochondrion is the key organelle for cellular respiration. Mitochondrial proteome analysis is difficult to perform by the classical proteomic approach involving two-dimensional gel electrophoresis (2DE), because this organelle contains a large number of membrane-associated and highly alkaline proteins usually requiring specific treatments to be successfully analyzed. Here, an alternative approach was evaluated and led to the rapid and sensitive identification of approximately 35% of the yeast mitochondrial proteins. It consists of an SDS-PAGE gel electrophoresis of the total mitochondrial protein in combination with the LC-MS/MS analysis of the digestion products of gel slices. The use of only 40 microg of mitochondrial protein enabled the identification of 179 different gene products divided into similar proportions of membrane and soluble proteins. The distribution of the identified proteins in terms of pI and hydrophobicity revealed that the present analytical strategy is largely unbiased. The identification of 28 proteins of previously unknown subcellular localization demonstrated the ability of SDS-PAGE-LC-MS/MS to rapidly supplement the knowledge of the mitochondrial proteome.