The effect of recombinant TGFalpha, human milk, and human milk macrophage media on gut epithelial proliferation is decreased in the presence of a neutralizing TGFalpha antibody

Cytokines in milk and the role of TGF-beta

Cytokines are required for normal growth and development of the mammary gland and TGF-β prominently represents an established effector of apoptosis, e.g., during involution of the mammary gland. By the control of intracellular signaling pathways, including JAK/STAT, MAPK, PI-3K, and NF-κB, cytokines efficiently regulate cell proliferation and inflammation in the breast. Therefore, cytokines are discussed also in a context of malignant mammary growth. As a group of tissue hormones produced by somatic cells or by cells from the immune system, cytokines are defined by their immunomodulatory potential. Over the past 40 years, multiple cytokines were identified in colostrum and milk. Importantly, cytokines derived from mammary secretions after birth are required for maturation of the immune system in the developing gastrointestinal tract from the suckling. Moreover, recent studies have further assessed the particular interactions between probiotic bacterial strains and cytokines. In light of the increasing prevalence of inflammatory diseases of the gastrointestinal system, the effects of probiotic microorganisms during milk fermentation may have immunotherapeutic potential in the future.

An optimized method for accurate quantification of cell migration using human small intestine cells

Quantifying the ability of a compound to modulate cell migration rate is a crucial part of many studies including those on chemotaxis, wound healing and cancer metastasis. Existing migration assays all have their strengths and weaknesses. The "scratch" assay is the most widely used because it seems appealingly simple and inexpensive. However, the scratch assay has some important limitations, as the tool introducing the "wound" might injure/stress the boundary cells and/or harm underlying matrix coatings, which in both cases will affect cell migration. This described method is a Cell Exclusion Zone Assay, in which cell-free areas are created by growing cells around removable silicone stoppers. Upon appropriate staining with fluorescent dyes and microscopically visualizing the monolayers, the migration rate is then quantified by counting the cells (nuclei) intruding the void area left by the silicone insert. In the current study human small intestine epithelial cells were seeded on a physiological substrate matrix to produce collectively migrating monolayers. Different substrates were tested to determine the optimal surface for enterocyte adherence and migration and morphological changes monitored. Recombinant human epidermal growth factor and osteopontin purified from urine were tested to see if the established migration assay produces accurate and reliable migration data with human small intestine cells. The obtained data accurately confirmed that the two bioactive proteins modulate cellular migration in a dose-dependent manner. The presented assay can likely be converted for use with other adherent cell lines or substrate matrices and allows for high throughput, while cost is kept low and versatility high. Co-staining can be applied in order to assay for cell death, different cell types, cell stress and others allowing intricate analysis of migration rate of mixed populations and correction for cell viability.

Carotenoids of aleurone, germ, and endosperm fractions of barley, corn and wheat differentially inhibit oxidative stress

The antioxidant potential of carotenoids from aleurone, germ, and endosperm fractions of barley, corn, and wheat has been evaluated. HPLC analysis confirmed the presence of lutein and zeaxanthin carotenoids (nd-15139 μg/kg) in extracts of cereal grain fractions. The antioxidant properties using 2,2-diphenyl-1-picrylhydrazyl, oxygen radical absorbance capacity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays revealed significantly higher (P<0.001) antioxidant activity in the germ than in the aleurone and endosperm fractions. Using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay, 2,2'azobis (2-amidinopropane)dihydrochloride (AAPH)-induced cell loss was effectively reduced by preincubating Caco-2, HT-29, and FHs 74 Int cells with carotenoid extracts. Moreover, carotenoid extracts reduced (P<0.001) AAPH-induced intracellular oxidation in the cell lines, suggesting antioxidant activity. Of the 84 antioxidant pathway genes included in microarray array analysis (HT-29 cells), the expressions of 28 genes were enhanced (P<0.05). Our findings suggest that carotenoids of germ, aleurone, and endosperm fractions improved antioxidant capacity and thus have the potential to mitigate oxidative stress.

Biochemical and molecular impacts of lactoferrin on small intestinal growth and development during early life1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal's usual peer review process

Postnatal modeling of the intestinal epithelium has long-term impacts on the healthy development of infants and relies largely on nutrient composition of the diet. Lactoferrin (Lf) is among the various human milk trophic factors that facilitate the infant intestinal adaptation. Hydrolysis of Lf is minimal at the prevailing postprandial pH of infants, and Lf may therefore have greater biological potential in infants than in adults. Lf bidirectionally stimulates concentration-dependent proliferation and differentiation of small intestinal epithelial cells, and therefore affects small intestinal mass, length, and epithelial digestive enzyme expression. A 105 kDa Lf receptor (LfR) specifically mediates the uptake of Lf into enterocytes and crypt cells. Mechanistically, the complex of Lf and LfR is internalized through clathrin-mediated endocytosis; both iron-free apo-Lf and iron-saturated holo-Lf activate the PI3K/Akt pathway, whereas only apo-Lf triggers ERK1/2 signaling. Lf enters the nucleus, where it can stimulate thymidine incorporation into crypt cells, regulating transcription of genes such as TGF-β1. In the fetus, the plasma membrane LfR is at the highest abundance in the small intestine, and the receptor gene is tightly controlled at multiple levels. Aspecific microRNA, miR-584, is involved in the posttranscriptional regulation of LfR, and in the human LfR DNA promoter, 2 Sp1 binding sites have been characterized functionally. Finally, cell proliferation and global gene expression reveal that native bovine Lf can perform biological activities similar to those exerted by human Lf in postnatal small intestinal development.

Gut health immunomodulatory and anti-inflammatory functions of gut enzyme digested high protein micro-nutrient dietary supplement-Enprocal

BACKGROUND

Enprocal is a high-protein micro-nutrient rich formulated supplementary food designed to meet the nutritional needs of the frail elderly and be delivered to them in every day foods. We studied the potential of Enprocal to improve gut and immune health using simple and robust bioassays for gut cell proliferation, intestinal integrity/permeability, immunomodulatory, anti-inflammatory and anti-oxidative activities. Effects of Enprocal were compared with whey protein concentrate 80 (WPC), heat treated skim milk powder, and other commercially available milk derived products.

RESULTS

Enprocal (undigested) and digested (Enprocal D) selectively enhanced cell proliferation in normal human intestinal epithelial cells (FHs74-Int) and showed no cytotoxicity. In a dose dependent manner Enprocal induced cell death in Caco-2 cells (human colon adencarcinoma epithelial cells). Digested Enprocal (Enprocal D: gut enzyme cocktail treated) maintained the intestinal integrity in transepithelial resistance (TEER) assay, increased the permeability of horseradish peroxidase (HRP) and did not induce oxidative stress to the gut epithelial cells. Enprocal D upregulated the surface expression of co-stimulatory (CD40, CD86, CD80), MHC I and MHC II molecules on PMA differentiated THP-1 macrophages in coculture transwell model, and inhibited the monocyte/lymphocyte (THP-1/Jurkat E6-1 cells)-epithelial cell adhesion. In cytokine secretion analyses, Enprocal D down-regulated the secretion of proinflammatory cytokines (IL-1beta and TNF-alpha) and up-regulated IFN-gamma, IL-2 and IL-10.

CONCLUSION

Our results indicate that Enprocal creates neither oxidative injury nor cytotoxicity, stimulates normal gut cell proliferation, up regulates immune cell activation markers and may aid in the production of antibodies. Furthermore, through downregulation of proinflammatory cytokines, Enprocal appears to be beneficial in reducing the effects of chronic gut inflammatory diseases such as inflammatory bowel disease (IBD). Stimulation of normal human fetal intestinal cell proliferation without cell cytotoxicity indicates it may also be given as infant food particularly for premature babies.

Host factors in amniotic fluid and breast milk that contribute to gut maturation

The gut represents a complex organ system with regional differences, which reflect selective digestive and absorptive functions that change constantly in response to bodily requirements and the outside milieu. As a barrier to the external environment, gut epithelium must be renewed rapidly and repeatedly. Growth and renewal of gut epithelial cells is dependent on controlled cell stimulation and proliferation by a number of signaling processes and agents, including gut peptides-both endogenous and exogenous sources. This cascade of events begins during fetal development; with the ingestion of amniotic fluid, this process is enhanced and continued during infancy and early childhood through the ingestion of human milk. Events influenced by amniotic fluid during fetal development and those influenced by human milk that unfold after birth and early childhood to render the gut mature are presented.

Oligosaccharides from human milk influence growth-related characteristics of intestinally transformed and non-transformed intestinal cells

Human milk oligosaccharides (HMO) are considered to influence the composition of the gut microflora in breastfed infants. We investigated direct effects of milk HMO fractions or individual oligosaccharides on proliferation, differentiation and apoptosis in transformed human intestinal cells (HT-29 and Caco-2) and non-transformed small intestinal epithelial crypt cells of fetal origin (human intestinal epithelial cells; HIEC). We observed growth inhibition induced by neutral and acidic HMO fractions in HT-29, Caco-2 and HIEC cells in a dose dependent manner. However, the effects varied between cell lines, i.e. HT-29 and Caco-2 cells were more sensitive than HIEC cells. In HT-29, all 16 individual neutral and acidic oligosaccharides except from the two fucosyllactoses had an inhibitory effect on cell growth. Regarding the induction of differentiation in HT-29 and HIEC cells a threshold concentration was observed at 7.5 mg/ml for neutral and acidic HMO fractions. Among individual oligosaccharides, only sialyllactoses induced differentiation in HT-29 and HIEC cells; no effect neither of fractions nor of individual oligosaccharides was found in Caco-2 cells. A strong induction of apoptosis was only detected in HT-29 and HIEC cells for neutral oligosaccharide but not for acidic fractions. HMO were shown to induce growth inhibition in intestinal cells through two different mechanisms, by suppressing cell cycle progression through induction of differentiation and/or by influencing apoptosis. As the development and maturation of digestive and absorptive processes depend on differentiation our experiments show that oligosaccharides are effective at influencing various stages in gastrointestinal development in vitro.

Trophic effect of multiple growth factors in amniotic fluid or human milk on cultured human fetal small intestinal cells

OBJECTIVES

To evaluate the role of growth factors in amniotic fluid and in human milk on gastrointestinal adaptation of the fetus and very low-birth-weight infants, the effects of these fluids and multiple growth factors were investigated in a human fetal small intestinal cell line (FHs 74 Int).

METHODS

After FHs 74 Int cells were incubated with amniotic fluid, human milk, or recombinant growth factors, growth-promoting activity was measured by [3H]-thymidine incorporation into cells.

RESULTS

Incubating cells with amniotic fluid or human milk promoted growth dose dependently. Genistein almost completely inhibited growth-promoting activity in amniotic fluid P = 0.002), and growth was partially inhibited by antibodies against epidermal growth factor (EGF) (P = 0.047), insulin-like growth factor-1 (IGF-1, P = 0.047), or fibroblast growth factor (FGF, P = 0.014). This activity in human milk was inhibited almost completely by genistein (P < 0.0001) and partially inhibited by antibodies against EGF (P = 0.036), IGF-1 (P = 0.009), FGF (P = 0.004), hepatocyte growth factor (HGF, P = 0.001), or transforming growth factor-alpha (TGF-alpha, P = 0.001). Although recombinant EGF, IGF-1, FGF, HGF, and TGF-alpha elicited a synergistic trophic response on cultured cells, the response was much less than with amniotic fluid or with human milk.

CONCLUSION

In aminiotic fluid and in human milk, EGF, IGF-1, FGF, HGF, and TGF-alpha have a strong trophic effect on immature intestinal cells and may be involved in perinatal gastrointestinal adaptation.

Effect of human milk fortifier on the immunodetection and molecular mass profile of transforming growth factor-alpha

OBJECTIVE

To determine if the addition of human milk fortifier (HMF) affects the distribution, immunoreactivity, or molecular mass profile of transforming growth factor-alpha (TGF-alpha) within the compartments of human milk.

METHODS

Fifteen milk samples were obtained. Each sample was divided into two aliquots; a powdered HMF was added to the first aliquot. TGF-alpha concentration was measured via radioimmunoassay in whole milk and its aqueous and fat fractions +/- HMF. TGF-alpha molecular mass profiles of the samples (v/v) were measured via Western blotting.

RESULTS

TGF-alpha concentration (mean +/- SD) in fortified whole milk (15.7 +/- 7.1 pg/100 microl) vs. nonfortified whole milk (14.8 +/- 8.0 pg/100 microl) and in the aqueous fraction of fortified (14.0 +/- 2.7 pg/100 microl) vs. nonfortified (14.0 +/- 3.5 pg/100 microl) did not differ statistically. There was, however, a marked decrease in the concentration of TGF-alpha in the fat fraction of fortified (30.6 +/- 2.8 pg/100 microl) vs. nonfortified (98.0 +/- 6.9 pg/100 microl) milk samples. Western blot for TGF-alpha in whole milk and its separated fractions revealed characteristic bands at 6.5, 12-16, 22, 26-30 and 46 kD. HMF alone and HMF with sodium taurocholate had a prominent band at 18 kD and fainter bands at 6.5, 26-30, and 46 kD. While whole and aqueous milk samples with HMF also consistently showed the 18-kD band, in 8/15 fat fraction samples with HMF the 18-kD band was nondetectable and was only faintly detectable in the remaining 7/15 samples.

CONCLUSIONS

It appears that HMF differentially alters the biochemical profile of human milk with regard to TGF-alpha concentration and molecular mass profile. What effect this alteration in human milk biochemistry has on neonatal gut function remains unknown.