Galacto-oligosaccharides exert a protective effect against heat stress in a Caco-2 cell model
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)
- et al.
Prebiotics as functional foods: A review
Journal of Functional Foods
(2013) - et al.
Galacto-oligosaccharides and colorectal cancer: Feeding our intestinal probiome
Journal of Functional Foods
(2015) - et al.
Secreted heat shock protein 90α (HSP90α) induces nuclear factor-κB-mediated TCF12 protein expression to down-regulate E-cadherin and to enhance colorectal cancer cell migration and invasion
The Journal of Biological Chemistry
(2013) - et al.
Cellular and molecular mechanisms of heat stress-induced up-regulation of occludin protein expression: Regulatory role of heat shock factor-1
The American Journal of Pathology
(2008) - et al.
The turn motif is a phosphorylation switch that regulates the binding of Hsp70 to protein kinase C
The Journal of Biological Chemistry
(2002) - et al.
Hydrophilic interaction liquid chromatography coupled to mass spectrometry for the characterization of prebiotic galactooligosaccharides
Journal of Chromatography. A
(2012) - et al.
The phorbol ester 12-O-Tetradecanoylphorbol 13-acetate enhances the heat-induced stress response
The Journal of Biological Chemistry
(1997) - et al.
Induction of heat shock proteins for protection against oxidative stress
Advanced Drug Delivery Reviews
(2009) - et al.
Heat stress induces epithelial plasticity and cell migration independent of heat shock factor 1
Cell Stress and Chaperones
(2012) - et al.
Differential induction of Hsp70-encoding genes in human hematopoietic cells
The Journal of Biological Chemistry
(2001)
Influences of structures of galactooligosaccharides and fructooligosaccharides on the fermentation in vitro by human intestinal microbiota
Journal of Functional Foods
Effect of supplementation of prebiotic mannan-oligosaccharides and probiotic mixture on growth performance of broilers subjected to chronic heat stress
Poultry Science
Effect of a probiotic mixture on intestinal microflora, morphology, and barrier integrity of broilers subjected to heat stress
Poultry Science
The dimethylthiourea-induced attenuation of cisplatin nephrotoxicity is associated with the augmented induction of heat shock proteins
Toxicology and Applied Pharmacology
Disease prevention by natural antioxidants and prebiotics acting as ROS scavengers in the gastrointestinal tract
Trends in Food Science & Technology
Effect of hyaluronan oligosaccharides on the expression of heat shock protein 72
The Journal of Biological Chemistry
Prebiotic oligosaccharides reduce proinflammatory cytokines in intestinal Caco-2 cells via activation of PPARγ and peptidoglycan recognition protein 3
The Journal of Nutrition
Protective effect of galactooligosaccharide-supplemented enteral nutrition on intestinal barrier function in rats with severe acute pancreatitis
Clinical Nutrition (Edinburgh, Scotland)
Heat shock factors: Integrators of cell stress, development and lifespan
Nature Reviews. Molecular Cell Biology
Heat stroke
The New England Journal of Medicine
Management of heat stroke
Trends in Anaesthesia and Critical Care
Antioxidative and hepatoprotective effects of fructo-oligosaccharide in D-galactose-treated Balb/cJ mice
The British Journal of Nutrition
A universal measure of chaotropicity and kosmotropicity
Environmental Microbiology
Physiologically relevant increase in temperature causes an increase in intestinal epithelial tight junction permeability
American Journal of Physiology. Gastrointestinal and Liver Physiology
Cited by (42)
Chronic heat stress induces the disorder of gut transport and immune function associated with endoplasmic reticulum stress in growing pigs
2022, Animal NutritionCitation Excerpt :Because of decreased blood flood towards mesenteric circulation, the gut barrier is easily subjected to heat stress, which adversely affects the integrity of the intestinal epithelium (Lambert, 2009). Multiple in vitro and in vivo studies have demonstrated that heat stress weakens gut integrity and compromises gut barrier function, leading to a leaky gut (Cui and Gu, 2015; Varasteh et al., 2015). The heat-induced leaky gut enhanced translocation of bacteria endotoxins and antigens into the bloodstream, which in turn initiated an inflammatory response and cytokine production (including IL-6, IL-1beta and TNF-alpha) (Cui et al., 2019).
Galactooligosaccharides as a protective agent for intestinal barrier and its regulatory functions for intestinal microbiota
2022, Food Research InternationalMicrobiota-gut-brain axis and nutritional strategy under heat stress
2021, Animal NutritionSupplemental Zinc exerts a positive effect against the heat stress damage in intestinal epithelial cells: Assays in a Caco-2 model
2021, Journal of Functional Foods