In vitro simulation of gastric digestion of milk proteins: comparison between in vitro and in vivo data

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

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Menstrual flow as a non-invasive source of endometrial organoids

Communications Biology ◽

10.1038/s42003-021-02194-y ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Tereza Cindrova-Davies ◽

Xiaohui Zhao ◽

Kay Elder ◽

Carolyn J. P. Jones ◽

Ashley Moffett ◽

...

Keyword(s):

Early Pregnancy ◽

Recurrent Miscarriage ◽

Milk Proteins ◽

Receptor Expression ◽

In Vitro Fertilisation ◽

Non Invasive ◽

Menstrual Flow ◽

Pregnancy Hormones

AbstractAssessment of the endometrium often necessitates a biopsy, which currently involves an invasive, transcervical procedure. Here, we present an alternative technique based on deriving organoids from menstrual flow. We demonstrate that organoids can be derived from gland fragments recovered from menstrual flow. To confirm they faithfully reflect the in vivo state we compared organoids derived from paired scratch biopsies and ensuing menstrual flow from patients undergoing in vitro fertilisation (IVF). We demonstrate that the two sets of organoids share the same transcriptome signature, derivation efficiency and proliferation rate. Furthermore, they respond similarly to sex steroids and early-pregnancy hormones, with changes in morphology, receptor expression, and production of ‘uterine milk’ proteins that mimic those during the late-secretory phase and early pregnancy. This technique has wide-ranging impact for non-invasive investigation and personalised approaches to treatment of common gynaecological conditions, such as endometriosis, and reproductive disorders, including failed implantation after IVF and recurrent miscarriage.

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Mechanisms of displacement of sperm basic nuclear proteins in mammals. An in vitro simulation of post-fertilization results

Journal of Cell Science ◽

10.1242/jcs.53.1.227 ◽

1982 ◽

Vol 53 (1) ◽

pp. 227-244

Author(s):

T.C. Rodman ◽

F.H. Pruslin ◽

V.G. Allfrey

Keyword(s):

Sperm Nucleus ◽

Nuclear Proteins ◽

Mouse Sperm ◽

Basic Proteins ◽

Molecular Events ◽

In Vitro Simulation ◽

Sperm Nuclei ◽

Two Parameters

A standardized cytological preparation of mature mouse sperm has been devised to serve as an in vitro system for probing the intra-ooplasmic molecular events of transformation of the fertilizing sperm. Two parameters of the early phase of transformation in vivo are defined at the resolution of the light microscope: deletion of sperm-unique nuclear proteins, detectable by immunofluorescence, and retention of homogeneity of the residual DNA complex, with intact chromatin boundaries detectable by ethidium bromide staining. These studies show that both parameters are conserved when in vitro sperm preparations are treated with NaCl under reducing conditions. The deletion of 2 different classes of the unique basic proteins of mouse sperm nuclei is specified by the NaCl concentration: 0.7 M-NaCl displaces the non-protamine class but not the protamines, while 1 M-NaCl displaces both. On the other hand the effects of treatment with trypsin at various concentrations and intervals are less consistent with the in vivo parameters, indicating fragmentation and displacement, not only of the sperm-unique basic proteins, but also of structural proteins believed to maintain the fundamental cohesive organization of the DNA matrix. These observations suggest that mechanisms other than proteolysis, e.g. localized changes in ionic concentrations, may participate in the post-fertilization displacement of the sperm-unique nuclear proteins in vivo. This study also supports the validity of the in vitro simulation as a model with which to probe the progression of transformation of the sperm nucleus to the zygote pronucleus.

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Influence of Pasteurization and Storage on Dynamic In Vitro Gastric Digestion of Milk Proteins: Quantitative Insights Based on Peptidomics

Foods ◽

10.3390/foods9080998 ◽

2020 ◽

Vol 9 (8) ◽

pp. 998 ◽

Cited By ~ 1

Author(s):

Xing Li ◽

Yuxiang Gu ◽

Shudong He ◽

Olayemi Eyituoyo Dudu ◽

Qiming Li ◽

...

Keyword(s):

Cold Storage ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Milk Proteins ◽

Hydrolysis Rate ◽

Gastric Digestion ◽

Pasteurized Milk ◽

The Impact ◽

And Storage

It is important to evaluate the nutritional quality of milk during the shelf-life, especially during home storage, from a consumer viewpoint. In this study, we investigated the impact of pasteurization (85 °C/15 s) and subsequent storage (at 4 °C for 7 days) on the coagulation behavior of milk and protein digestibility in a dynamic in vitro gastric digestion test. A high level of hydration in curd formed in pasteurized milk upon 7-day cold storage compared to raw and pasteurized milk, indicating fast pepsin diffusion in the interior of curds, increasing the hydrolysis rate. The digesta collected at various time points throughout the gastric digestion were studied using o-phthaldialdehyde (OPA), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), liquid chromatography tandem mass spectrometry (LC-MS/MS), and amino acid analysis. These results showed that milk proteins were hydrolyzed quickly upon a long period of cold storage. Additionally, qualitative and quantitative results obtained using LC-MS/MS exhibited significant differences between samples, especially in pasteurized milk upon cold storage. Processing and storage played a decisive role in bioactive peptide generation. Such knowledge could provide insights into and directions for the storage of pasteurized milk for further clinical studies on protein bioavailability and the generation of bioactive peptides for desired health outcomes.

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Effect of Low-Immunogenic Yogurt Drinks and Probiotic Bacteria on Immunoreactivity of Cow’s Milk Proteins and Tolerance Induction—In Vitro and In Vivo Studies

Nutrients ◽

10.3390/nu12113390 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3390

Author(s):

Barbara Wróblewska ◽

Anna Kaliszewska-Suchodoła ◽

Ewa Fuc ◽

Lidia Hanna Markiewicz ◽

Anna Maria Ogrodowczyk ◽

...

Keyword(s):

Therapeutic Potential ◽

Tolerance Induction ◽

Milk Proteins ◽

In Vivo Studies ◽

Cow’S Milk ◽

Milk Allergy ◽

Cow's Milk ◽

Safe Product

There is no effective therapy for milk allergy. The role of lactic acid bacteria (LAB) and probiotics in protection against allergy-related outcomes is still under investigation. The aim of the study was to evaluate the immunomodulative and therapeutic potential of yogurt drinks in cow’s milk allergy (CMA) management. We compared immunoreactivity of α-casein (α-CN), β-casein (β-CN), κ-casein (κ-CN), α-lactalbumin (α-LA), and β-lactoglobulin (β-LG) in 27 yogurt drinks fermented with different basic yogurt cultures, or yogurt cultures enriched with Lactobacillus plantarum and/or Bifidobacterium lactis strains, by competitive ELISA assay. Drinks with the lowest antigenic potential were used as allergoids for CMA therapy. BALB/c mice were sensitized via intraperitoneal injection of α-CN + β-LG mixture with aluminum adjuvant, and gavaged with increasing doses of selected low-immunogenic drinks (YM—basic, or YM-LB—enriched with L. plantarum and B. lactis) to induce tolerance. Milk- or phosphate-buffered saline (PBS)-dosed mice served as controls. Compared to milk, the immunoreactivity of proteins in drinks increased or decreased, depending on the bacterial sets applied for fermentation. Only a few sets acted synergistically in reducing immunoreactivity. The selected low-immunogenic drinks stimulated allergic mice for profiling Th2 to Th1 response and acquire tolerance, and the effect was greater with YM-LB drink, which during long-lasting interventional feeding strongly increased the secretion of regulatory cytokines, i.e., IL-10 and TGF-β, and IgA and decreased IL-4, IgE, and anti-(α-CN + β-LG) IgG1. The studies revealed variations in the potency of yogurt bacteria to change allergenicity of milk proteins and the need for their strict selection to obtain a safe product for allergy sufferers. The YM-LB drink with reduced antigenic potential may be a source of allergoids used in the immunotherapy of IgE mediated CMA, but further clinical or volunteer studies are required.

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Are Faba Bean and Pea Proteins Potential Whey Protein Substitutes in Infant Formulas? An In Vitro Dynamic Digestion Approach

Foods ◽

10.3390/foods9030362 ◽

2020 ◽

Vol 9 (3) ◽

pp. 362

Author(s):

Linda Le Roux ◽

Olivia Ménard ◽

Raphaël Chacon ◽

Didier Dupont ◽

Romain Jeantet ◽

...

Keyword(s):

Faba Bean ◽

Whey Proteins ◽

Milk Proteins ◽

Protein Digestibility ◽

Cow Milk ◽

Partial Substitution ◽

Infant Formulas ◽

Pea Proteins

Infant formulas (IFs) are used as substitutes for human milk and are mostly based on cow milk proteins. For sustainability reasons, animal protein alternatives in food are increasingly being considered, as plant proteins offer interesting nutritional and functional benefits for the development of innovative IFs. This study aimed to assess how a partial substitution (50%) of dairy proteins with faba bean and pea proteins influenced the digestibility of IFs under simulated dynamic in vitro digestion, which were set up to mimic infant digestion. Pea- and faba bean-based IFs (PIF and FIF, respectively) have led to a faster aggregation than the reference milk-based IF (RIF) in the gastric compartment; that did not affect the digesta microstructure at the end of digestion. The extent of proteolysis was estimated via the hydrolysis degree, which was the highest for FIF (73%) and the lowest for RIF (50%). Finally, it was apparent that in vitro protein digestibility and protein digestibility-corrected amino acid score (PDCAAS)-like scores were similar for RIF and FIF (90% digestibility; 75% PDCAAS), but lower for PIF (75%; 67%). Therefore, this study confirms that faba bean proteins could be a good candidate for partial substitution of whey proteins in IFs from a nutritional point of view, provided that these in vitro results are confirmed in vivo.

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Survival of Bacillus cereus Vegetative Cells and Spores during In Vitro Simulation of Gastric Passage

Journal of Food Protection ◽

10.4315/0362-028x.jfp-11-481 ◽

2012 ◽

Vol 75 (4) ◽

pp. 690-694 ◽

Cited By ~ 22

Author(s):

SIELE CEUPPENS ◽

MIEKE UYTTENDAELE ◽

KATRIEN DRIESKENS ◽

ANDREJA RAJKOVIC ◽

NICO BOON ◽

...

Keyword(s):

Bacillus Cereus ◽

Acid Resistance ◽

In Vitro Experiments ◽

Vegetative Cells ◽

Ph Values ◽

Constant Ph ◽

In Vitro Simulation ◽

Ph Range

The enteric pathogen Bacillus cereus must survive gastric passage in order to cause diarrhea by enterotoxin production in the small intestine. The acid resistance and the survival after gastric passage were assessed by in vitro experiments with acidified growth medium and gastric simulation medium with B. cereus NVH 1230-88 vegetative cells and spores. First, batch incubations at constant pH values for 4 h, which represented different physiological states of the stomach, showed that spores were resistant to any gastric condition in the pH range of 2.0 to 5.0, while vegetative cells were rapidly inactivated at pH values of ≤4.0. Second, a dynamic in vitro gastric experiment was conducted that simulated the continuously changing in vivo conditions due to digestion dynamics by gradually decreasing the pH from 5.0 to 2.0 and fractional emptying of the stomach 30 to 180 min from the start of the experiment. All of the B. cereus spores and 14% (±9%) of the vegetative cells survived the dynamic simulation of gastric passage.

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Digestion of micellar casein in duodenum cannulated pigs. Correlation between in vitro simulated gastric digestion and in vivo data

Food Chemistry ◽

10.1016/j.foodchem.2020.128424 ◽

2021 ◽

Vol 343 ◽

pp. 128424 ◽

Cited By ~ 1

Author(s):

B. Miralles ◽

J. Sanchón ◽

L. Sánchez-Rivera ◽

D. Martínez-Maqueda ◽

Y. Le Gouar ◽

...

Keyword(s):

Gastric Digestion ◽

Micellar Casein

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Biologically active casein peptides implicated in immunomodulation

Journal of Dairy Research ◽

10.1017/s0022029900028806 ◽

1989 ◽

Vol 56 (3) ◽

pp. 357-362 ◽

Cited By ~ 115

Author(s):

D. Migliore-Samour ◽

F. Floc'h ◽

P. Jollès

Keyword(s):

Synthetic Peptides ◽

Viral Infections ◽

Milk Proteins ◽

Biologically Active ◽

Passive Immunity ◽

Maternal Milk ◽

Enzymic Digestion ◽

Immunomodulating Peptides

SummaryMaternal milk should not only be considered as a nutrient, but also as a protecting agent against aggressions from the neonate's new environment. Breastfeeding facilitates transmission of a passive immunity by multifunctional factors which have a direct effect on the neonate's resistance to bacterial and viral infections. Among these factors are the main milk proteins, the caseins: during enzymic digestion of human and bovine caseins, immunomodulating peptides are released. Corresponding synthetic peptides stimulated in vitro phagocytic activity of murine and of human macrophages and exerted in vivo a protective effect against Klebsiella pneumoniae infection of mice. These data suggest that casein peptides may exert a stimulating function on the immune system of the newborn.

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