Elsevier

Journal of Functional Foods

Volume 16, June 2015, Pages 265-277
Journal of Functional Foods

Galacto-oligosaccharides exert a protective effect against heat stress in a Caco-2 cell model

https://doi.org/10.1016/j.jff.2015.04.045Get rights and content

Highlights

  • GOS prevent the heat-induced up-regulation of HSPs on mRNA and protein level.

  • GOS reduce the heat-induced stress response in Caco-2 cells.

  • GOS protect the heat-induced disruption of the intestinal epithelial barrier.

Abstract

Thermal stress can evoke a stress response and enhance the synthesis of heat shock proteins, while gut barrier dysfunction is considered as an important adverse effect of thermal stress. Considering the previously described effects of galacto-oligosaccharides, nowadays mainly used in infant formulas, we hypothesized that galacto-oligosaccharides may protect the intestinal barrier against heat stress. Human epithelial colorectal adenocarcinoma cells were pre-treated with galacto-oligosaccharides prior to thermal stress exposure (40–42 °C) for 24 h. Pre-treatment of galacto-oligosaccharides prevented the heat stress-induced up-regulation of heat shock proteins and reduced the heat-induced stress response as observed by a decrease in haem oxygenase-1. Galacto-oligosaccharides partly prevented the heat-induced effects on monolayer integrity as measured by transepithelial electrical resistance, paracellular permeability and E-cadherin expression. In addition to their prebiotic effect, galacto-oligosaccharides may have beneficial potency to protect the intestinal epithelial barrier against heat stress and may be an attractive dietary application for people who are at high risk of developing heat stress.

Introduction

The cellular stress response is a protective reaction of individual cells to potentially harmful internal and external stimuli. It is well established that exposure of cells to various stressors, including thermal stress, oxidative stress, or pathological conditions like ischaemia, tissue damage, infection and inflammation (Morimoto, 2011, Ragsdale, Proctor, 2000, Tsuji et al, 2009) can evoke a stress response and enhance the synthesis of heat shock proteins (HSPs), via activation of heat shock factors (Akerfelt, Morimoto, & Sistonen, 2010). HSPs prevent stress-induced protein aggregation and misfolding, and promote their return to native conformations maintaining protein homeostasis (Kalmar & Greensmith, 2009). They are classified into different groups based on their molecular weight, structure and function, including families of small HSPs (molecular weight of 15–30 kDa), HSP60, HSP70, HSP90 and HSP110 (Joly, Wettstein, Mignot, Ghiringhelli, & Garrido, 2010). Although HSPs are generally considered to improve cellular recovery, imbalances in HSP70 and HSP90 levels can induce cell growth arrest and developmental defects (Nollen & Morimoto, 2002). An alteration in the expression of HSPs, but also thermoregulatory failure and dysregulation of the acute-phase response may contribute to the progression of heat stress into heat stroke. Heat stroke is a potentially fatal disorder characterized by multi-organ injury and an elevated core body temperature that rises above 40 °C. Heat stroke may result from exposure to high environmental temperatures (classical heat stroke) or as a consequence of extensive exercise (exertional heat stroke) (Chan & Mamat, 2015). Heat-induced multi-organ injury may include varying degrees of central nervous system dysfunction, acute renal failure, liver failure, skeletal muscle injury and gut ischaemia (Leon & Helwig, 2010). An important early symptom of thermal stress is a dysfunction of the intestinal barrier leading to increased intestinal permeability and as a consequence increased entrance of toxic luminal substances (Dokladny et al, 2006, Xiao et al, 2013). With the prospect of increasing global warming and increase in frequency and intensity of heat stress (Bouchama & Knochel, 2002), it is important to investigate preventive measures that can alleviate adverse effects of exposure to high environmental temperatures. Food supplemented with non-digestible oligosaccharides, including galacto-oligosaccharides (GOS) are known to support the maintenance of the gut homeostasis, modulate the intestinal microbiome, protect the intestinal barrier integrity and stimulate gut associated immunity (Bruno-Barcena, Azcarate-Peril, 2015, Jeurink et al, 2013, Zhong et al, 2009). Considering these effects of GOS on improving gut health, we hypothesized that dietary GOS might protect the epithelial barrier against the heat stress-induced effects on HSPs expression levels, on oxidative stress, and on the intestinal barrier integrity. In this study, an in vitro epithelial colorectal adenocarcinoma (Caco-2) cell culture model was used as a model to assess the effects of thermal stress on the expression of heat shock proteins as well as on the intestinal barrier function and to investigate the potential protective effects of GOS. Results show that in this in vitro model, dietary GOS prevented heat-induced up-regulation of HSPs and markers of oxidative stress. The heat stress-induced disruption of the intestinal barrier was mitigated by GOS especially by modulating epithelial-cadherin (E-cadherin) expression.

Section snippets

Galacto-oligosaccharides (GOS)

The commercial product Vivinal® GOS syrup (FrieslandCampina Domo, Borculo, The Netherlands) containing galacto-oligosaccharides with a degree of polymerization (dp) of 2–8 was used. The final product contained approximately 59% (w/w) galacto-oligosaccharides, 21% (w/w) lactose, 19% (w/w) glucose and 1% (w/w) galactose on dry matter (dry matter of 75%) and dilutions (1% and 2.5% (w/v) GOS) were produced in complete cell culture medium. Before starting the experiments close to equimolar

Heat stress does not affect cell viability

To determine the effects of GOS as well as heat stress exposure without treatment on the survival of the Caco-2 cell monolayers, a LDH leakage assay was performed. The results indicated that neither GOS in the used test concentration nor heat stress at 40 °C and 42 °C for 24 h did impair Caco-2 cell viability (Supplementary Fig. S1).

Heat stress up-regulates the mRNA expression of HSPs and disrupts intestinal barrier integrity

Before investigating the effects of GOS, the effect of heat stress on HSP gene expression and intestinal barrier integrity was investigated at different time points

Discussion

Non-digestible oligosaccharides, like GOS, are known as functional food ingredients that can modify the gut function by enhancing the growth of beneficial bacteria, stimulating immune responses and maintaining the intestinal barrier integrity (Al-Sheraji et al, 2013, van Hoffen et al, 2009, Zhong et al, 2009). Therefore, we hypothesized that dietary GOS could protect the intestinal epithelial barrier against heat-induced effects on intestinal barrier integrity, oxidative stress and associated

Conclusion

Our results indicate that galacto-oligosaccharides protect the intestinal epithelial barrier against heat stress as observed by a decrease in heat-induced HSP70 and HSP90 on mRNA and protein levels, and by a suppression of the heat-induced oxidative stress response. Furthermore, in the absence of measureable changes in expression of TJ proteins, thermal stress-induced disruption of the intestinal epithelial barrier can be particularly associated with the derangement of E-cadherin, which is

References (49)

  • LiW. et al.

    Influences of structures of galactooligosaccharides and fructooligosaccharides on the fermentation in vitro by human intestinal microbiota

    Journal of Functional Foods

    (2015)
  • M.U. Sohail et al.

    Effect of supplementation of prebiotic mannan-oligosaccharides and probiotic mixture on growth performance of broilers subjected to chronic heat stress

    Poultry Science

    (2012)
  • SongJ. et al.

    Effect of a probiotic mixture on intestinal microflora, morphology, and barrier integrity of broilers subjected to heat stress

    Poultry Science

    (2014)
  • T. Tsuji et al.

    The dimethylthiourea-induced attenuation of cisplatin nephrotoxicity is associated with the augmented induction of heat shock proteins

    Toxicology and Applied Pharmacology

    (2009)
  • W. Van den Ende et al.

    Disease prevention by natural antioxidants and prebiotics acting as ROS scavengers in the gastrointestinal tract

    Trends in Food Science & Technology

    (2011)
  • XuH. et al.

    Effect of hyaluronan oligosaccharides on the expression of heat shock protein 72

    The Journal of Biological Chemistry

    (2002)
  • M. Zenhom et al.

    Prebiotic oligosaccharides reduce proinflammatory cytokines in intestinal Caco-2 cells via activation of PPARγ and peptidoglycan recognition protein 3

    The Journal of Nutrition

    (2011)
  • ZhongY. et al.

    Protective effect of galactooligosaccharide-supplemented enteral nutrition on intestinal barrier function in rats with severe acute pancreatitis

    Clinical Nutrition (Edinburgh, Scotland)

    (2009)
  • M. Akerfelt et al.

    Heat shock factors: Integrators of cell stress, development and lifespan

    Nature Reviews. Molecular Cell Biology

    (2010)
  • A. Bouchama et al.

    Heat stroke

    The New England Journal of Medicine

    (2002)
  • Y.K. Chan et al.

    Management of heat stroke

    Trends in Anaesthesia and Critical Care

    (2015)
  • ChenH.-L. et al.

    Antioxidative and hepatoprotective effects of fructo-oligosaccharide in D-galactose-treated Balb/cJ mice

    The British Journal of Nutrition

    (2011)
  • J.A. Cray et al.

    A universal measure of chaotropicity and kosmotropicity

    Environmental Microbiology

    (2013)
  • K. Dokladny et al.

    Physiologically relevant increase in temperature causes an increase in intestinal epithelial tight junction permeability

    American Journal of Physiology. Gastrointestinal and Liver Physiology

    (2006)
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