Reduction in heat-induced gastrointestinal hyperpermeability in rats by bovine colostrum and goat milk powders

Milk: A Natural Guardian for the Gut Barrier

The gut barrier plays an important role in health maintenance by preventing the invasion of dietary pathogens and toxins. Disruption of the gut barrier can cause severe intestinal inflammation. As a natural source, milk is enriched with many active constituents that contribute to numerous beneficial functions, including immune regulation. These components collectively serve as a shield for the gut barrier, protecting against various threats such as biological, chemical, mechanical, and immunological threats. This comprehensive review delves into the active ingredients in milk, encompassing casein, α-lactalbumin, β-lactoglobulin, lactoferrin, the milk fat globular membrane, lactose, transforming growth factor, and glycopeptides. The primary focus is to elucidate their impact on the integrity and function of the gut barrier. Furthermore, the implications of different processing methods of dairy products on the gut barrier protection are discussed. In conclusion, this study aimed to underscore the vital role of milk and dairy products in sustaining gut barrier health, potentially contributing to broader perspectives in nutritional sciences and public health.

Biological Relevance of Goat Milk Oligosaccharides to Infant Health

Milk is often regarded as the gold standard for the nourishment of all mammalian offspring. The World Health Organization (WHO) recommends exclusive breastfeeding for the first 6 months of the life of the infant, followed by a slow introduction of complementary foods to the breastfeeding routine for a period of approximately 2 years, whenever this is possible ( Global Strategy for Infant and Young Child Feeding; WHO, 2003). One of the most abundant components in all mammals' milk, which is associated with important health benefits, is the oligosaccharides. The milk oligosaccharides (MOS) of humans and other mammals differ in terms of their concentration and diversity. Among those, goat milk contains more oligosaccharides (gMOS) than other domesticated dairy animals, as well as a greater range of structures. This review summarizes the biological functions of MOS found in both human and goat milk to identify the possible biological relevance of gMOS in human health and development. Based on the existing literature, seven biological functions of gMOS were identified, namely, MOS action as prebiotics, immune modulators, and pathogen traps; their modulation of intestinal cells; protective effect against necrotizing enterocolitis; improved brain development; and positive effects on stressor exposure. Overall, goat milk is a viable alternate supply of functional MOS that could be employed in a newborn formula.

Amino acid solution mitigates hypothermia response and intestinal damage following exertional heat stroke in male mice

Increased gut permeability is implicated in the initiation and extent of the cytokine inflammatory response associated with exertional heat stroke (EHS). The primary objective of this study was to determine if a five amino acid oral rehydration solution (5AAS), specifically designed for the protection of the gastrointestinal lining, would prolong time to EHS, maintain gut function and dampen the systemic inflammatory response (SIR) measured during EHS recovery. Male C57/BL6J mice instrumented with radiotelemetry were gavaged with 150 μL of 5AAS or H2 O, and ≈12 h later were either exposed to an EHS protocol where mice exercised in a 37.5°C environmental chamber to a self-limiting maximum core temperature (Tc,max) or performed the exercise control (EXC) protocol (25°C). 5AAS pretreatment attenuated hypothermia depth and length (p < 0.005), which are indicators of EHS severity during recovery, without any effect on physical performance or thermoregulatory responses in the heat as determined by percent body weight lost (≈9%), max speed (≈6 m/min), distance (≈700 m), time to Tc,max (≈160 min), thermal area (≈550°C∙min), and Tc,max (42.2°C). EHS groups treated with 5AAS showed a significant decrease in gut transepithelial conductance, decreased paracellular permeability, increased villus height, increased electrolyte absorption and changes in tight junction protein expression pattern suggestive of improved barrier integrity (p < 0.05). No differences were witnessed between EHS groups in acute phase response markers of liver, circulating SIR markers, or indicators of organ damage during recovery. These results suggest that a 5AAS improves Tc regulation during EHS recovery through maintaining mucosal function and integrity.

Exertional heat stroke: nutritional considerations

NEW FINDINGS

What is the topic of this review? The potential role of nutrition in exertional heat stroke. What advances does it highlight? Certain nutritional and dietary strategies used by athletes and workers may exert a protective effect the pathophysiological processes of exertional heat stroke, whereas others may be detrimental. While current evidence suggests that some of these practices may be leveraged as a potential countermeasure to exertional heat stroke, further research on injury-related outcomes in humans is required.

ABSTRACT

Exertional heat stroke (EHS) is a life-threatening illness and an enduring problem among athletes, military servicemen and -women, and occupational labourers who regularly perform strenuous activity, often under hot and humid conditions or when wearing personal protective equipment. Risk factors for EHS and mitigation strategies have generally focused on the environment, health status, clothing, heat acclimatization and aerobic conditioning, but the potential role of nutrition is largely underexplored. Various nutritional and dietary strategies have shown beneficial effects on exercise performance and health and are widely used by athletes and other physically active populations. There is also evidence that some of these practices may dampen the pathophysiological features of EHS, suggesting possible protection or abatement of injury severity. Promising candidates include carbohydrate ingestion, appropriate fluid intake and glutamine supplementation. Conversely, some nutritional factors and low energy availability may facilitate the development of EHS, and individuals should be cognizant of these. Therefore, the aims of this review are to present an overview of EHS along with its mechanisms and pathophysiology, discuss how selected nutritional considerations may influence EHS risk focusing on their impact on the key pathophysiological processes of EHS, and provide recommendations for future research. With climate change expected to increase EHS risk and incidence in the coming years, further investigation on how diet and nutrition may be optimized to protect against EHS would be highly beneficial.

Sport supplements and the athlete's gut: a review

Vigorous or prolonged exercise poses a challenge to gastrointestinal system functioning and is associated with digestive symptoms. This narrative review addresses 1) the potential of dietary supplements to enhance gut function and reduce exercise-associated gastrointestinal symptoms and 2) strategies for reducing gastrointestinal-related side effects resulting from popular sports supplements. Several supplements, including probiotics, glutamine, and bovine colostrum, have been shown to reduce markers of gastrointestinal damage and permeability with exercise. Yet, the clinical ramifications of these findings are uncertain, as improvements in symptoms have not been consistently observed. Among these supplements, probiotics modestly reduced exercise-associated gastrointestinal symptoms in a few studies, suggesting they are the most evidenced-based choice for athletes looking to manage such symptoms through supplementation. Carbohydrate, caffeine, and sodium bicarbonate are evidence-based supplements that can trigger gastrointestinal symptoms. Using glucose-fructose mixtures is beneficial when carbohydrate ingestion is high (>50 g/h) during exercise, and undertaking multiple gut training sessions prior to competition may also be helpful. Approaches for preventing caffeine-induced gastrointestinal disturbances include using low-to-moderate doses (<500 mg) and avoiding/minimizing exacerbating factors (stress, anxiety, other stimulants, fasting). Adverse gastrointestinal effects of sodium bicarbonate can be avoided by using enteric-coated formulations, low doses (0.2 g/kg), or multi-day loading protocols.

Effects of colostrum feeding on the mRNA abundance of genes related to toll-like receptors, key antimicrobial defense molecules, and tight junctions in the small intestine of neonatal dairy calves

The objective of the present study was to elucidate the effect of feeding either colostrum or milk-based formula on the mRNA abundance of genes related to pathogen recognition [toll-like receptors (TLR1-10)], antimicrobial defense [β-defensin 1 (DEFB1) and peptidoglycan recognition protein 1 (PGLYRP1)], and tight junctions (claudin 1 = CLDN1, claudin 4 = CLDN4, and occludin = OCLN) in different sections of the small intestine of neonatal calves at d 4 of life. Holstein dairy calves were fed either colostrum (COL; n = 7) or milk-based formula (FOR; n = 7) with comparable nutrient composition but lower contents of several bioactives in the formula than in the respective colostrum group until d 4 of life. Following euthanasia on d 4 (2 h after feeding), tissue samples from the duodenum, jejunum (proximal, middle, and distal), and ileum were collected. The mRNA abundance of the target genes was quantified by quantitative PCR. The mRNA abundance of TLR1, TLR6, TLR9, and TLR10 were greater in COL than in FOR calves. However, the mRNA abundance of TLR2, TLR3, TLR4, TLR5, and TLR7 did not differ between groups. A group × gut region interaction was observed for the mRNA abundance of TLR8 with greater values in duodenum and proximal jejunum of COL than in FOR calves but in the more distal regions, in mid and distal jejunum, and ileum, this diet effect disappeared or was reversed. We observed greater mRNA abundance of TLR1 in the jejunum (middle and distal) and ileum, TLR2, TLR4, TLR6, and TLR9-10 in the distal jejunum and ileum, and of TLR3 in the distal jejunum, and TLR5, TLR7, and TLR8 in the ileum compared with the other gut regions. The mRNA abundance of PGLYRP1, DEFB1, and OCLN did not differ between groups. The mRNA abundance of CLDN1 was greater, but the CLDN4 mRNA tended to be lower in COL than in FOR calves. The mRNA abundance of PGLYRP1 was lower in the distal jejunum and DEFB1 mRNA in the middle jejunum compared with the other gut regions. The mRNA abundances of OCLN and CLDN4 were greater in the duodenum, and of CLDN1 in the middle and proximal jejunum compared with the other gut regions. Overall, the greater mRNA abundance of 5 different TLR, and CLDN1 in most intestinal sections of the COL calves may suggest that feeding colostrum improves immune responsiveness and epithelial barrier function in neonatal calves.

Endotoxin Translocation and Gut Inflammation Are Increased in Broiler Chickens Receiving an Oral Lipopolysaccharide (LPS) Bolus during Heat Stress

Lipopolysaccharides (LPS), also termed endotoxins, are the major component of the outer membrane of Gram-negative bacteria. In general, endotoxins in the intestine are considered harmless in healthy animals. However, different stressors, such as heat stress, can lead to a compromised gut barrier, resulting in endotoxin translocation. Chickens are considered to be less sensitive to the effects of LPS compared with other species, for example, humans, pigs, or calves, probably because of the lack of the functional-specific TRAM-TRIF signalling pathway (MyD88-independent). Therefore, six LPS preparations (three different strains with two different preparation methods each) were compared in murine macrophages and characterized according to their MyD88-dependent pathway activation. All tested LPS preparations induced a strong inflammatory response after 4 and 24 h on a murine macrophage cell line. However, there was a similar strong response in the gene expression profile as well as production of nitrite oxide and TNF-alpha from LPS of different strains and preparation methods. On the basis of the results of the in vitro study, one LPS preparation was chosen for the subsequent in vivo study with broilers to assess the effect of an oral LPS bolus (E. coli O55:B5 phenol extracted; 2 mg/kg b.w.) during heat stress conditions (10 h, 36 °C). The most pronounced effects were seen in broilers receiving the oral LPS bolus during heat stress conditions. The endotoxin activity in the intestine as well as the serum concentration of the 3-OH C14 (part of LPS) were increased. In addition, an increased expression of genes related to inflammation and stress response (e.g., IL-6, IL-1beta, HSP70) was observed, whereas the expression of genes associated with gut health (e.g., MUC2, FABP2) was decreased. To conclude, an increase of intestinal LPS combined with heat stress can pose a risk to animal health.

The Gastrointestinal Exertional Heat Stroke Paradigm: Pathophysiology, Assessment, Severity, Aetiology and Nutritional Countermeasures

Exertional heat stroke (EHS) is a life-threatening medical condition involving thermoregulatory failure and is the most severe condition along a continuum of heat-related illnesses. Current EHS policy guidance principally advocates a thermoregulatory management approach, despite growing recognition that gastrointestinal (GI) microbial translocation contributes to disease pathophysiology. Contemporary research has focused to understand the relevance of GI barrier integrity and strategies to maintain it during periods of exertional-heat stress. GI barrier integrity can be assessed non-invasively using a variety of in vivo techniques, including active inert mixed-weight molecular probe recovery tests and passive biomarkers indicative of GI structural integrity loss or microbial translocation. Strenuous exercise is strongly characterised to disrupt GI barrier integrity, and aspects of this response correlate with the corresponding magnitude of thermal strain. The aetiology of GI barrier integrity loss following exertional-heat stress is poorly understood, though may directly relate to localised hyperthermia, splanchnic hypoperfusion-mediated ischemic injury, and neuroendocrine-immune alterations. Nutritional countermeasures to maintain GI barrier integrity following exertional-heat stress provide a promising approach to mitigate EHS. The focus of this review is to evaluate: (1) the GI paradigm of exertional heat stroke; (2) techniques to assess GI barrier integrity; (3) typical GI barrier integrity responses to exertional-heat stress; (4) the aetiology of GI barrier integrity loss following exertional-heat stress; and (5) nutritional countermeasures to maintain GI barrier integrity in response to exertional-heat stress.

Heat Stress Directly Affects Intestinal Integrity in Broiler Chickens

A study using pair-feeding technique was conducted to determine whether heat exposure directly or indirectly (via reduced feed intake) increases intestinal mucosal damage and permeability to endotoxin in broiler chickens. Male broiler chickens (Ross 308), 27-d-old, were subjected to one of the three treatments (n=8): 1) thermo-neutral conditions (24°C) with ad libitum feed intake, 2) heat stress conditions (33°C) with ad libitum feed intake, or 3) pair-feeding under thermo-neutral conditions, with the feed intake identical to that of heat-stressed chickens. Using these groups, two experiments were performed to evaluate temporal changes in the intestinal morphology in response to each treatment. In experiment 1, chickens were sacrificed after 24 h of exposure to the treatment conditions, while in experiment 2, chickens were sacrificed after 12 or 72 h of exposure to the treatment conditions. In experiment 1, exposure to heat stress conditions for 24 h significantly decreased both the villus height to crypt depth ratio and number of proliferating cell nuclear antigen (PCNA)-positive cells in the duodenum and increased the plasma endotoxin concentration. These findings were not observed in pair-fed chickens. In experiment 2, intestinal integrity and function were unaffected by 12 h of heat stress. On the other hand, chickens exposed to heat stress for 72 h exhibited significantly damaged intestinal morphology in the duodenum as well as increased plasma endotoxin concentration; these negative effects were not observed in pair-fed chickens. These findings suggest that the intestinal morphology and permeability changes observed in chickens that are heat-stressed for 24–72 h are due to the heat stress conditions and not due to reduced feed intake.

A Prospective, Open-Label Comparison of Tamsulosin plus Serenoa repens and Bovine Colostrum versus Tamsulosin Alone in the Treatment of Benign Prostatic Hyperplasia

OBJECTIVE

To compare the efficacy and safety of oral supplementation with Serenoa repens (SR) and bovine colostrum (BC) plus tamsulosin (TAM) versus TAM alone over 12 months in men suffering from lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH).

METHODS

Between February 2018 and February 2019, men with symptomatic BPH (IPSS ≥10) were prospectively recruited. This prospective, open-label, 12-month study included two different protocols: (1) group A, SR 320 mg/day + BC 30 mg/day + TAM 0.4 mg/day, and (2) group B, TAM 0.4 mg/day only.

RESULTS

Overall, 148 patients entered the study, 76 in group A and 72 in group B. At 12 months, the total IPSS had decreased by 5.5 with TAM + SR + BC and by 5.1 with TAM only (p = 0.21). However, when the total IPSS was divided into storage and voiding subscores, at 6 months the storage symptoms had improved significantly more with TAM + SR + BC (-1.6 vs. -0.9 with TAM only, p = 0.02), with the benefit persisting also at the 1-year evaluation (-1.8 vs. -0.8, p = 0.02). Moreover, the improvement in LUTS-related quality of life (QoL) was significantly different between the groups, with a mean decrease in IPSS QoL subscore of -2.5 ± 0.2 for TAM + SR + BC versus -1.8 ± 0.3 for TAM at 6 months (p = 0.04), and of -2.9 ± 0.4 for TAM + SR + BC versus -2.1 ± 0.4 for TAM at 12 months (p = 0.04). Conversely, no significant differences were found in maximal urinary flow rate (p = 0.38), postvoid residual volume (p = 0.12), prostate-specific antigen (p = 0.41), and prostate volume (p = 0.16).

CONCLUSION

Combination treatment with SR and BC plus TAM was shown to be more effective than treatment with TAM only in improving IPSS storage and QoL subscores in BPH patients after 6 months and up to 12 months of treatment.

Effects of early enteral bovine colostrum supplementation on intestinal permeability in critically ill patients: A randomized, double-blind, placebo-controlled study

OBJECTIVES

In this study we sought to investigate the effect of early enteral bovine colostrum supplementation on intestinal permeability in intensive care unit (ICU)-hospitalized patients.

METHODS

A total of 70 ICU-hospitalized adult patients were randomly assigned to receive a bovine colostrum supplement or placebo according to the stratified blocked randomization by age and admission category. Plasma endotoxin and zonulin concentrations were measured on days 5 and 10 of intervention.

RESULTS

Out of 70 participants, 32 patients in the colostrum group and 30 patients in the control group were included in the final analysis of the outcomes. Plasma endotoxin concentration decreased significantly in the colostrum group on the 10th day (P < 0.05). Furthermore, plasma levels of zonulin reduced in the colostrum group significantly compared with the placebo group (P < 0.001).The incidence of diarrhea was significantly lower in the colostrum group than in the control group (P = 0.02).

CONCLUSIONS

Our results provide evidence that bovine colostrum supplementation may have beneficial effects on intestinal permeability and gastrointestinal complications in ICU-hospitalized patients. Further studies are needed to investigate the exact mechanism of action of these effects.

The effects of colostrum on some biochemical parameters in the experimental intoxication of rats with paracetamol

In the current study, the possible prophylactic and therapeutic effects of colostrum (COL) on acute organ injury caused by paracetamol (PAR) in rats were evaluated. Within the scope of this study, a 2-month-old male (150-200 g) 70 Wistar Albino rat was used and a total of seven groups were designed. The first group (CNT) was maintained for control purposes. The second group (COL-1) was given COL for 1 day, at a dose of 500 mg/kg at 6-h intervals, and blood and tissue sampling was performed at 24 h. The third group (COL-7) received COL for 7 days, at a dose of 500 mg/kg at 6-h intervals on day 1 and at a daily dose of 500 mg/kg on the following days, and blood and tissue samples were taken at the end of seventh day. The fourth group (PAR-1) was administered with PAR at a dose of 1.0 g/kg bw and was blood and tissue sampled at 24 h. The fifth group (PAR-7) received PAR at a dose of 1.0 g/kg bw on day 1 and was blood and tissue was removed at the end of day 7. The sixth group (PAR+COL-1) was administered with a combination of PAR (1 g/kg bw) and COL (500 mg/kg at 6-h intervals), and blood and tissue samples were collected at 24 h. The seventh group (PAR+COL-7) received 1.0 g/kg bw of PAR on day 1 and was given COL throughout the 7-day study period (at a dose of 500 mg/kg at 6-h intervals on day 1 and at a daily dose of 500 mg/kg on the following days). In the seventh group, blood and tissue samples were taken at the end of seventh day. Alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), glucose, creatinine, triglyceride, total bilirubin, total protein and albumin levels/activities were analysed in the serum samples. The malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) levels/activities, known as oxidative stress parameters, were assayed for tissue homogenates and blood (erythrocytes/plasma); in addition, enzyme activities of GSH S-transferase (GST), cytochrome P4502E1 (CYP2E1), NADH-cytochrome b5 reductase (CYTB5), glucose-6-phosphate dehydrogenase (G6PD), NADPH-cytochrome P450 C reductase (CYTC) and glutathione (GSH) levels/activities defined as drug metabolising parameters were measured in liver homogenates. In result, it was determined that PAR caused significant alterations in some biochemical and lipid peroxidation parameters and the activities/levels of drug metabolising parameters in the liver and that COL normalised some of these parameters and reduced PAR-induced tissue damage.

The effect of bovine colostrum supplementation on intestinal injury and circulating intestinal bacterial DNA following exercise in the heat

Purpose

Exercise-induced changes in intestinal permeability are exacerbated in the heat. The aim of this study was to determine the effect of 14 days of bovine colostrum (Col) supplementation on intestinal cell damage (plasma intestinal fatty acid-binding protein, I-FABP) and bacterial translocation (plasma bacterial DNA) following exercise in the heat.

Methods

In a double-blind, placebo-controlled, crossover design, 12 males completed two experimental arms (14 days of 20 g/day supplementation with Col or placebo, Plac) consisting of 60 min treadmill running at 70% maximal aerobic capacity (30 °C, 60% relative humidity). Blood samples were collected pre-exercise (Pre-Ex), post-exercise (Post-Ex) and 1 h post-exercise (1 h Post-Ex) to determine plasma I-FABP concentration, and bacterial DNA (for an abundant gut species, Bacteroides).

Results

Two-way repeated measures ANOVA revealed an arm × time interaction for I-FABP (P = 0.005, with greater Post-Ex increase in Plac than Col, P = 0.01: Plac 407 ± 194% of Pre-Ex vs Col, 311 ± 134%) and 1 h Post-Ex (P = 0.036: Plac 265 ± 80% of Pre-Ex vs Col, 229 ± 56%). There was no interaction (P = 0.904) but there was a main effect of arm (P = 0.046) for plasma Bacteroides/total bacterial DNA, with lower overall levels evident in Col.

Conclusion

This is the first investigation to demonstrate that Col can be effective at reducing intestinal injury following exercise in the heat, but exercise responses (temporal pattern) of bacterial DNA were not influenced by Col (although overall levels may be lower).

Heat stress modulated gastrointestinal barrier dysfunction: role of tight junctions and heat shock proteins

Increased environmental temperature exerts a visible impact on an individual's physiology. At the onset of heat stress, there is an increase in core body temperature which triggers peripheral vasodilation and sweating in an effort to dissipate the elevated body heat. The increase in peripheral circulation however reduces blood flow to the internal organs which are thus adversely affected. In particular, the gastrointestinal (GI) tract gets adversely affected during hyperthermia resulting in loosening of the tight junctions (TJs) that finally leads to higher intestinal permeability. At the cellular level, elevated levels of heat shock proteins (HSPs) induced in response to heat stress mediated cytoprotection by maintaining proper protein folding, releasing survival signals and preserving cytoskeleton integrity. Recent studies have indicated that HSPs play a crucial role in maintaining the localization of TJ proteins. Dietary supplements have also shown to have a positive effect on the maintenance of intestinal TJs. Therefore, it becomes imperative to understand the cellular, molecular and physiological alterations in response to heat stress in GI tract. In the present report, the effect of thermal stress on GI tract has been summarized. Specific role of HSPs along with mitogen activated protein (MAP) kinase signaling pathway in response to hyperthermia has also been discussed.

Heat stress and dehydration in adapting for performance: Good, bad, both, or neither?

Physiological systems respond acutely to stress to minimize homeostatic disturbance, and typically adapt to chronic stress to enhance tolerance to that or a related stressor. It is legitimate to ask whether dehydration is a valuable stressor in stimulating adaptation per se. While hypoxia has had long-standing interest by athletes and researchers as an ergogenic aid, heat and nutritional stressors have had little interest until the past decade. Heat and dehydration are highly interlinked in their causation and the physiological strain they induce, so their individual roles in adaptation are difficult to delineate. The effectiveness of heat acclimation as an ergogenic aid remains unclear for team sport and endurance athletes despite several recent studies on this topic. Very few studies have examined the potential ergogenic (or ergolytic) adaptations to ecologically-valid dehydration as a stressor in its own right, despite longstanding evidence of relevant fluid-regulatory adaptations from short-term hypohydration. Transient and self-limiting dehydration (e.g., as constrained by thirst), as with most forms of stress, might have a time and a place in physiological or behavioral adaptations independently or by exacerbating other stressors (esp. heat); it cannot be dismissed without the appropriate evidence. The present review did not identify such evidence. Future research should identify how the magnitude and timing of dehydration might augment or interfere with the adaptive processes in behaviorally constrained versus unconstrained humans.

Gastritis and Gastric Ulcers in Working Dogs

Gastritis and gastric ulcers are an important cause of morbidity and mortality in canine athletes. Although the majority of scientific work on this condition has been performed in ultraendurance racing sled dogs, this condition has been identified in other canine athletes, including sled dogs competing in shorter events and dogs performing off-leash explosive detection duties. The cause of the syndrome is unknown, but current hypotheses propose a link between exercise-induced hyperthermia and loss of gastric mucosal barrier function as an early event in the pathogenesis. Treatment is focused on prevention of clinical disease using acid secretion inhibitors, such as omeprazole, which has excellent efficacy in controlled clinical studies.

Intestinal epithelial barrier function and tight junction proteins with heat and exercise

A single layer of enterocytes and tight junctions (intercellular multiprotein complexes) form the intestinal epithelial barrier that controls transport of molecules through transcellular and paracellular pathways. A dysfunctional or "leaky" intestinal tight junction barrier allows augmented permeation of luminal antigens, endotoxins, and bacteria into the blood stream. Various substances and conditions have been shown to affect the maintenance of the intestinal epithelial tight junction barrier. The primary focus of the present review is to analyze the effects of exertional or nonexertional (passive hyperthermia) heat stress on tight junction barrier function in in vitro and in vivo (animals and humans) models. Our secondary focus is to review changes in tight junction proteins in response to exercise or hyperthermic conditions. Finally, we discuss some pharmacological or nutritional interventions that may affect the cellular mechanisms involved in maintaining homeostasis of the intestinal epithelial tight junction barrier during heat stress or exercise.

Effect of exercise on gastric health in field retrievers

Exercise-induced gastrointestinal disease (EIGD) has been reported in all domestic athletes. In dogs and humans, EIGD is most commonly associated with ultra-endurance racing sled dogs and marathon/triathlon competitors, respectively, suggesting that the syndrome is specifically a function of prolonged exercise. However, EIGD is also common in horses that exercise for brief periods, and more recently, EIGD has been identified in Labrador retrievers that perform off-leash explosive detection patrols. In this study, we tested the hypothesis that EIGD could be induced in retrievers performing competition-style retrieves. Gastric endoscopy and histopathological examination of gastric biopsies were performed on 10 healthy retrievers before and 24 h after a series of multi-set retrieves totalling over 5 km. Although the exercise challenge resulted in a small but statistically significant increase in gastric endoscopy severity score, it did not result in a higher prevalence of clinically-significant gastric disease or changes in gastric histopathology. We conclude that competitive retrieving is unlikely to induce clinically-significant gastric disease in healthy dogs.

Acute Heat Stress and Reduced Nutrient Intake Alter Intestinal Proteomic Profile and Gene Expression in Pigs

Heat stress and reduced feed intake negatively affect intestinal integrity and barrier function. Our objective was to compare ileum protein profiles of pigs subjected to 12 hours of HS, thermal neutral ad libitum feed intake, or pair-fed to heat stress feed intake under thermal neutral conditions (pair-fed thermal neutral). 2D-Differential In Gel Electrophoresis and gene expression were performed. Relative abundance of 281 and 138 spots differed due to heat stress, compared to thermal neutral and pair-fed thermal neutral pigs, respectively. However, only 20 proteins were different due to feed intake (thermal neutral versus pair-fed thermal neutral). Heat stress increased mRNA expression of heat shock proteins and protein abundance of heat shock proteins 27, 70, 90-α and β were also increased. Heat stress reduced ileum abundance of several metabolic enzymes, many of which are involved in the glycolytic or TCA pathways, indicating a change in metabolic priorities. Stress response enzymes peroxiredoxin-1 and peptidyl-prolyl cis-trans isomerase A were decreased in pair-fed thermal neutral and thermal neutral pigs compared to heat stress. Heat stress increased mRNA abundance markers of ileum hypoxia. Altogether, these data show that heat stress directly alters intestinal protein and mRNA profiles largely independent of reduced feed intake. These changes may be related to the reduced intestinal integrity associated with heat stress.

The impact of heat stress on intestinal function and productivity in grow-finish pigs

Heat stress is a physiological condition when animals can no longer regulate their internal euthermic temperature. When livestock such as pigs are subjected to this environmental stress, it can be detrimental to performance, health and well-being, and if severe enough even death. Growing pigs are particularly susceptible to heat stress and one of the major organs first affected by heat stress is the gastrointestinal tract. As a result, reductions in appetite, intestinal function and integrity and increased risk of endotoxemia can modify post-absorptive metabolism and tissue accretion. These changes in intestinal integrity may be a result of altered expression of tight junction proteins, increased circulating endotoxin concentrations and markers of cellular stress (heat shock and hypoxia response), which is evident as early on as 2 h after heat-stress onset. Due to restricted blood flow, the ileum is more severely affected compared with the colon. Interestingly, many of the negative effects of heat stress on intestinal integrity appear to be similar to those observed with pigs reared under reduced nutrient and caloric intakes. Altogether, these depress pig performance and health, and extend days to market. Despite this impact on the gastrointestinal tract, under heat-stress conditions, intestinal glucose transport pathways are upregulated. This review discussed how heat stress (directly and indirectly via reduced feed intake) affects intestinal integrity and how heat stress contributes to decreased growth performance in growing pigs.

Nutritional and Physical Activity Interventions to Improve Immunity

Physical activity and nutrition are important in a healthy lifestyle with potential benefits to immunity often overlooked. Infection of the upper respiratory tract, and the associated symptoms, are the most frequent presentations to general practitioners and may have significant economic and social impact. In this review, we consider the role of physical activity and nutrition in improving immunity. Evidence suggests that regular moderate activity is particularly beneficial for immune enhancement and reducing the risk of infection. We also discuss some nutritional strategies. Unfortunately, the evidence for many is weak. Avoiding nutritional deficiencies seems the most pragmatic recommendation. This can be achieved with a balanced diet. Including a variety of fruits and vegetables may help ensure adequate intake of essential nutrients with little risk of excess intake of any single nutrient. Supplementation with individual nutrients is generally not recommended. Multinutrients may be beneficial for those with a preexisting deficiency but not if normal dietary intake is sufficient. Further benefit may be gained from some supplements including probiotics, bovine colostrum, and some plant-derived products (Echinacea, black elderberry, and some polyphenols) but only in specific situations/contexts. Individuals should consider their personal needs, use caution, and avoid the indiscriminate use of supplements.

Effects of dairy products on intestinal integrity in heat-stressed pigs

Heat stress compromises intestinal integrity which may partially explain its negative effects on animal health and productivity. Research suggests that challenged intestinal barrier function improves with dietary dairy products in various models. Thus, the study objective was to evaluate the effects of bovine milk whey protein (WP) and colostral whey protein (CWP) on intestinal integrity in heat-stressed pigs. Crossbred gilts (39 ± 3 kg body weight) were fed 1 of 4 diets (n = 8 pigs/diet): control (Ct), control diet containing an 80% WP and 20% CWP product (WP80), control diet containing a 98% WP and 2% CWP product (WP98), and control diet containing a 100% WP product (WP100). After 7d on experimental diets, pigs were exposed to constant heat stress conditions (32 °C) for 24h. There were no treatment differences in growth or body temperature indices prior to heat stress. During heat exposure, both rectal temperature and respiration rate increased (+0.85 °C and 3-fold, respectively; P < 0.01), and feed intake and body weight decreased (44% and -0.5kg, respectively; P < 0.01), but neither variable was affected by dietary treatments. Plasma L-lactate and D-lactate concentrations increased (36%; P < 0.01) and tended to increase (19%; P = 0.09) with heat stress. After 24h of heat exposure, WP100-fed pigs had lower plasma D-lactate relative to Ct-fed pigs. Ileal transepithelial electrical resistance was decreased (37%; P = 0.02) in WP80 pigs, compared with controls. No differences were detected in other intestinal integrity ex vivo measurements. These data demonstrate that dietary WP and CWP did not mitigate intestinal integrity dysfunction during severe heat stress.

The role of tight junctions in mammary gland function

Tight junctions (TJ) are cellular structures that facilitate cell-cell communication and are important in maintaining the three-dimensional structure of epithelia. It is only during the last two decades that the molecular make-up of TJ is becoming unravelled, with two major transmembrane-spanning structural protein families, called occludin and claudins, being the true constituents of the TJ. These TJ proteins are linked via specific scaffolding proteins to the cell's cytoskeleton. In the mammary gland TJ between adjacent secretory epithelial cells are formed during lactogenesis and are instrumental in establishing and maintaining milk synthesis and secretion, whereas TJ integrity is compromised during mammary involution and also as result of mastitis and periods of mammary inflamation (including mastitis). They prevent the paracellular transport of ions and small molecules between the blood and milk compartments. Formation of intact TJ at the start of lactation is important for the establishment of the lactation. Conversely, loss of TJ integrity has been linked to reduced milk secretion and mammary function and increased paracellular transport of blood components into the milk and vice versa. In addition to acting as a paracellular barrier, the TJ is increasingly linked to playing an active role in intracellular signalling. This review focusses on the role of TJ in mammary function of the normal, non-malignant mammary gland, predominantly in ruminants, the major dairy producing species.

Overcrowding stress decreases macrophage activity and increases Salmonella Enteritidis invasion in broiler chickens

Overcrowding stress is a reality in the poultry industry. Chickens exposed to long-term stressful situations present a reduction of welfare and immunosuppression. We designed this experiment to analyse the effects from overcrowding stress of 16 birds/m(2) on performance parameters, serum corticosterone levels, the relative weight of the bursa of Fabricius, plasma IgA and IgG levels, intestinal integrity, macrophage activity and experimental Salmonella Enteritidis invasion. The results of this study indicate that overcrowding stress decreased performance parameters, induced enteritis and decreased macrophage activity and the relative bursa weight in broiler chickens. When the chickens were similarly stressed and infected with Salmonella Enteritidis, there was an increase in feed conversion and a decrease in plasma IgG levels in the stressed and Salmonella-infected birds. We observed moderate enteritis throughout the duodenum of chickens stressed and infected with Salmonella. The overcrowding stress decreased the macrophage phagocytosis intensity and increased Salmonella Enteritidis counts in the livers of birds challenged with the pathogenic bacterium. Overcrowding stress via the hypothalamic-pituitary-adrenal axis that is associated with an increase in corticosterone and enteritis might influence the quality of the intestinal immune barrier and the integrity of the small intestine. This effect allowed pathogenic bacteria to migrate through the intestinal mucosa, resulting in inflammatory infiltration and decreased nutrient absorption. The data strengthen the hypothesis that control of the welfare of chickens and avoidance of stress from overcrowding in poultry production are relevant factors for the maintenance of intestinal integrity, performance and decreased susceptibility to Salmonella infection.

Effect of simulated deployment patrols on gastric mucosa of explosive detection dogs

Exercise-induced gastric disease is well-recognised in dogs performing ultra-endurance racing, but has not been described in dogs performing non-competitive athletic activities. Explosive detection dogs often perform prolonged periods of exercise and are reported to have chronic inappetance and weight-loss consistent with gastric disease. Seven privately-owned Labrador Retrievers trained for off-leash explosive detection activities were used to test the hypothesis that explosive detection dogs develop exercise-induced gastric disease while performing routine duties. Gastroscopy was performed on dogs before and after a 5-day exercise challenge designed to simulate routine military deployment activities. Five days of sustained submaximal exercise resulted in substantial gastric disease. These results demonstrate that dogs performing prolonged submaximal exercise consistent with off-leash explosive detection patrols are susceptible to exercise-induced gastric disease. Exercise-induced gastric disease may explain the anecdotal reports of poor thrift in these types of dogs during military deployment, and prophylactic acid suppression therapy should be considered in dogs participating in these activities.

Inhibition of heat-induced apoptosis in rat small intestine and IEC-6 cells through the AKT signaling pathway

Background

As the world warms up, heat stress is becoming a major cause of economic loss in the livestock industry. Long-time exposure of animals to hyperthermia causes extensive cell apoptosis, which is harmful to them. AKT and AKT-related serine–threonine kinases are known to be involved in signaling cascades that regulate cell survival, but the mechanism remains elusive. In the present study, we demonstrate that phosphoinositide 3-kinase (PI3K) /AKT signal pathway provides protection against apoptosis induced by heat stress to ascertain the key point for treatment.

Results

Under heat stress, rats showed increased shedding of intestinal epithelial cells. These rats also had elevated levels of serum cortisol and improved expression of heat shock proteins (Hsp27, Hsp70 and Hsp90) in response to heat stress. Apoptosis analysis by TUNEL assay revealed a higher number of villi epithelial cells that were undergoing apoptosis in heat-treated rats than in the normal control. This is supported by gene expression analysis, which showed an increased ratio of Bax/Bcl-2 (p < 0.05), an important indicator of apoptosis. During heat-induced apoptosis, more AKTs were activated, showing increased phosphorylation. An increase of BAD phosphorylation, which is an inhibitory modification, ensued. In rat IEC-6 cell line, a significant higher level of AKT phosphorylation was observed at 2 h after heat exposure. This coincided with a marked reduction of apoptosis.

Conclusion

Together, these results suggest that heat stress caused damages to rat jejunum and induced apoptosis to a greater degree. HSPs and pro-survival factors were involved in response to heat stress. Among them, AKT played a key role in inhibiting heat-induced apoptosis.

Heat stress and reduced plane of nutrition decreases intestinal integrity and function in pigs

Heat stress can compromise intestinal integrity and induce leaky gut in a variety of species. Therefore, the objectives of this study were to determine if heat stress (HS) directly or indirectly (via reduced feed intake) increases intestinal permeability in growing pigs. We hypothesized that an increased heat-load causes physiological alterations to the intestinal epithelium, resulting in compromised barrier integrity and altered intestinal function that contributes to the overall severity of HS-related illness. Crossbred gilts (n=48, 43±4 kg BW) were housed in constant climate controlled rooms in individual pens and exposed to 1) thermal neutral (TN) conditions (20°C, 35-50% humidity) with ad libitum intake, 2) HS conditions (35°C, 20-35% humidity) with ad libitum feed intake, or 3) pair-fed in TN conditions (PFTN) to eliminate confounding effects of dissimilar feed intake. Pigs were sacrificed at 1, 3, or 7 d of environmental exposure and jejunum samples were mounted into modified Ussing chambers for assessment of transepithelial electrical resistance (TER) and intestinal fluorescein isothiocyanate (FITC)-labeled lipopolysaccharide (LPS) permeability (expressed as apparent permeability coefficient, APP). Further, gene and protein markers of intestinal integrity and stress were assessed. Irrespective of d of HS exposure, plasma endotoxin levels increased 45% (P<0.05) in HS compared with TN pigs, while jejunum TER decreased 30% (P<0.05) and LPS APP increased 2-fold (P<0.01). Furthermore, d 7 HS pigs tended (P=0.06) to have increased LPS APP (41%) compared with PFTN controls. Lysozyme and alkaline phosphatase activity decreased (46 and 59%, respectively; P<0.05) over time in HS pigs, while the immune cell marker, myeloperoxidase activity, was increased (P<0.05) in the jejunum at d 3 and 7. These results indicate that both HS and reduced feed intake decrease intestinal integrity and increase endotoxin permeability. We hypothesize that these events may lead to increased inflammation, which might contribute to reduced pig performance during warm summer months.

Heat stress reduces intestinal barrier integrity and favors intestinal glucose transport in growing pigs

Excessive heat exposure reduces intestinal integrity and post-absorptive energetics that can inhibit wellbeing and be fatal. Therefore, our objectives were to examine how acute heat stress (HS) alters intestinal integrity and metabolism in growing pigs. Animals were exposed to either thermal neutral (TN, 21°C; 35–50% humidity; n = 8) or HS conditions (35°C; 24–43% humidity; n = 8) for 24 h. Compared to TN, rectal temperatures in HS pigs increased by 1.6°C and respiration rates by 2-fold (P<0.05). As expected, HS decreased feed intake by 53% (P<0.05) and body weight (P<0.05) compared to TN pigs. Ileum heat shock protein 70 expression increased (P<0.05), while intestinal integrity was compromised in the HS pigs (ileum and colon TER decreased; P<0.05). Furthermore, HS increased serum endotoxin concentrations (P = 0.05). Intestinal permeability was accompanied by an increase in protein expression of myosin light chain kinase (P<0.05) and casein kinase II-α (P = 0.06). Protein expression of tight junction (TJ) proteins in the ileum revealed claudin 3 and occludin expression to be increased overall due to HS (P<0.05), while there were no differences in claudin 1 expression. Intestinal glucose transport and blood glucose were elevated due to HS (P<0.05). This was supported by increased ileum Na⁺/K⁺ ATPase activity in HS pigs. SGLT-1 protein expression was unaltered; however, HS increased ileal GLUT-2 protein expression (P = 0.06). Altogether, these data indicate that HS reduce intestinal integrity and increase intestinal stress and glucose transport.

Fibronectin-integrin signaling is required for L-glutamine's protection against gut injury

Background

Extracellular matrix (ECM) stabilization and fibronectin (FN)-Integrin signaling can mediate cellular protection. L-glutamine (GLN) is known to prevent apoptosis after injury. However, it is currently unknown if ECM stabilization and FN-Integrin osmosensing pathways are related to GLN’s cell protective mechanism in the intestine.

Methods

IEC-6 cells were treated with GLN with or without FN siRNA, integrin inhibitor GRGDSP, control peptide GRGESP or ERK1/2 inhibitors PD98059 and UO126 under basal and stressed conditions. Cell survival measured via MTS assay. Phosphorylated and/or total levels of cleaved caspase-3, cleaved PARP, Bax, Bcl-2, heat shock proteins (HSPs), ERK1/2 and transcription factor HSF-1 assessed via Western blotting. Cell size and F-actin morphology quantified by confocal fluorescence microscopy and intracellular GLN concentration by LC-MS/MS.

Results

GLN’s prevention of FN degradation after hyperthermia attenuated apoptosis. Additionally, inhibition of FN-Integrin interaction by GRGDSP and ERK1/2 kinase inhibition by PD98059 inhibited GLN’s protective effect. GRGDSP attenuated GLN-mediated increases in ERK1/2 phosphorylation and HSF-1 levels. PD98059 and GRGDSP also decreased HSP levels after GLN treatment. Finally, GRGDSP attenuated GLN-mediated increases in cell area size and disrupted F-actin assembly, but had no effect on intracellular GLN concentrations.

Conclusion

Taken together, this data suggests that prevention of FN degradation and the FN-Integrin signaling play a key role in GLN-mediated cellular protection. GLN’s signaling via the FN-Integrin pathway is associated with HSP induction via ERK1/2 and HSF-1 activation leading to reduced apoptosis after gut injury.

Hyperthermia induces injury to the intestinal mucosa in the mouse: evidence for an oxidative stress mechanism

Loss of the intestinal barrier is critical to the clinical course of heat illness, but the underlying mechanisms are still poorly understood. We tested the hypothesis that conditions characteristic of mild heatstroke in mice are associated with injury to the epithelial lining of the intestinal tract and comprise a critical component of barrier dysfunction. Anesthetized mice were gavaged with 4 kDa FITC-dextran (FD-4) and exposed to increasing core temperatures, briefly reaching 42.4°C, followed by 30 min recovery. Arterial samples were collected to measure FD-4 concentration in plasma (in vivo gastrointestinal permeability). The small intestines were then removed to measure histological evidence of injury. Hyperthermia resulted in a ≈2.5-fold elevation in plasma FD-4 and was always associated with significant histological evidence of injury to the epithelial lining compared with matched controls, particularly in the duodenum. When isolated intestinal segments from control animals were exposed to ≥41.5°C, marked increases in permeability were observed within 60 min. These changes were associated with release of lactate dehydrogenase, evidence of protein oxidation via carbonyl formation and histological damage. Coincubation with N-acetylcysteine protected in vitro permeability during hyperthermia and reduced histological damage and protein oxidation. Chelation of intracellular Ca(2+) to block tight junction opening during 41.5°C exposure failed to reduce the permeability of in vitro segments. The results demonstrate that hyperthermia exposure in mouse intestine, at temperatures at or below those necessary to induce mild heatstroke, cause rapid and substantial injury to the intestinal lining that may be attributed, in part, to oxidative stress.

The effect of early enteral nutrition on hyperthermic intraoperative intraperitoneal chemotherapy-induced mucosal permeability following gastrectomy

AIM

To investigate (1) the effect of hyperthermic intraoperative intraperitoneal chemotherapy (HIIC) on intestinal permeability of patients with advanced gastric cancer and (2) the protective effect of postoperative enteral nutrition (EN) on patients.

METHODS

All patients were divided randomly into 3 groups: the EN group, treated with EN during postoperative period; the EN+HIIC group, treated with HIIC and postoperative EN; and the PN+HIIC group, treated with HIIC and postoperative parenteral nutrition. The lactulose/mannitol (L/M) ratio was used to evaluate the permeability of intestinal mucous.

RESULTS

Compared with the ratio of L/M on the day before operation (POD-1), the ratio of L/M on POD+3 increased significantly in all 3 groups (P < .0001) and then decreased gradually. The L/M ratio of the EN and EN+HIIC groups recovered to the baseline on POD+12. In contrast, the PN+HIIC group still had an elevated L/M ratio until POD+12. The ratios of L/M in the EN+HIIC group on POD+7 and POD+12 were significantly different from those of the PN+HIIC group (0.0855 ± 0.0462 vs 0.1298 ± 0.063, P = .007; 0.0336 ± 0.0235 vs 0.0616 ± 0.0430, P = .038, respectively).

CONCLUSION

Gastric cancer radical resection resulted in a significant increase in intestinal permeability. HIIC aggravated the injury of intestinal mucous permeability, which could be reversed by EN.

Membrane-rich milk fat diet provides protection against gastrointestinal leakiness in mice treated with lipopolysaccharide

Milk fat globule membrane is a protein-lipid complex that may strengthen the gut barrier. The main objective of this study was to assess the ability of a membrane-rich milk fat diet to promote the integrity of the gut barrier and to decrease systemic inflammation in lipopolysaccharide (LPS)-challenged mice. Animals were randomly assigned to one of 2 American Institute of Nutrition (AIN)-76A formulations differing only in fat source: control diet (corn oil) and milk fat diet (anhydrous milk fat with 10% milk fat globule membrane). Each diet contained 12% calories from fat. Mice were fed diets for 5 wk, then injected with vehicle or LPS (10mg/kg of BW) and gavaged with dextran-fluorescein to assess gut barrier integrity. Serum was assayed for fluorescence 24h after gavage, and 16 serum cytokines were measured to assess the inflammatory response. Gut permeability was 1.8-fold higher in LPS-challenged mice fed the control diet compared with the milk fat diet. Furthermore, mice fed the milk fat diet and injected with LPS had lower serum levels of IL-6, IL-10, IL-17, monocyte chemotactic protein (MCP)-1, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and IL-3 compared with LPS-injected mice fed the control diet. The results indicate that the membrane-rich milk fat diet decreases the inflammatory response to a systemic LPS challenge compared with corn oil, and the effect coincides with decreased gut permeability.

Ileal endogenous amino acid flow of broiler chickens under high ambient temperature

High environmental temperature has detrimental effects on the gastrointestinal tract of poultry. An experiment was conducted to determine the effect of acute heat stress on endogenous amino acid (EAA) flow in broiler chickens. A total of 90, day-old broiler chicks were housed in battery cages in an environmentally controlled chamber. Chicks were fed a nitrogen-free diet on day 42 following either no heat exposure (no-heat) or 2 weeks exposure to 35 ± 1 °C for 3 h from days 28 to 42 (2-week heat) or 1 week exposure to 35 ± 1 °C for 3 h from days 35 to 42 (1 week heat). The most abundant amino acid in the ileal flow was glutamic acid, followed by aspartic acid, serine and threonine in non-heat stressed group. The EAA flow in 1-week heat and 2-week heat birds were significantly (p < 0.05) higher than those under no heat exposure (14682, 11161 and 9597 mg/kg of dry matter intake respectively). Moreover, the EAA flow of 2-week heat group was less than 1-week heat group by approximately 36%. These observations suggest that the effect of heat stress on EAA flow is mostly quantitative; however, heat stress may also alter the content of EAA flow qualitatively.

Deer velvet supplementation decreases the grade and metastasis of azoxymethane-induced colon cancer in the male rat

Since deer velvet (DV) extract promotes angiogenesis, its ability to modulate the growth and invasiveness of colon tumours was investigated. Male Wistar rats were each given a subcutaneous injection of azoxymethane (AOM) at 15 mg/kg once a week for 3 weeks. One week following the last dose of AOM the rats received either 1g/kg of DV delivered in a cube of raspberry gelatin or plain raspberry gelatin daily for 26 weeks. At necropsy, tumours were measured and the distance from the anus was recorded. Tissue samples were categorised according to the Astler-Coller system. The results showed that there were no significant differences in most parameters examined (i.e. body weight gain, multiplicity, tumour volume and incidence). The only statistically significant differences seen were associated with metastasis and tumour grade. Specifically, more of the tumours in the DV-treated rats were of a lower grade compared to the controls, both when all tumour sites were considered (0.91 vs. 0.66, p<0.0001), as well as those located only in the colon (0.95 vs. 0.84, p<0.03). Therefore, this study can confidently conclude that DV does not increase the incidence, multiplicity, metastasis or tumour volume of AOM-induced colon cancer in the rat.

Post-weaning effects of milk and milk components on the intestinal mucosa in inflammation

Many milk-derived components have immunomodulatory and anti-inflammatory properties, and some of these reduce intestinal inflammation when orally administered to animal models of colitis. However, the potential for ruminant milk or milk components to benefit people with intestinal inflammatory disorders (such as Inflammatory Bowel Disease) has not been well-researched. This review describes published research into mechanisms by which ruminant milk and its components may have beneficial effects when consumed by people who have intestinal inflammation.

Stress-induced gastrointestinal barrier dysfunction and its inflammatory effects

The intestinal barrier is formed by enterocyte membranes, tight junctions, secreted mucus, and immunologic factors, such as tissue macrophages. Dysfunction of this barrier can be caused by different types of stress (e.g., physiological, pathological, psychological, pharmacological) and can lead to increased intestinal permeability. Increased permeability to endotoxin, a component of the walls of gram-negative bacteria, causes local or systemic inflammatory reactions, or both. The immune response(s) can then promote more serious conditions. Exertional heat stroke is an example of such a condition. During severe exercise-heat stress, possibly combined with other stresses, reductions in intestinal blood flow, direct thermal damage to the intestinal mucosa, or both, can cause intestinal barrier disruption and endotoxemia. The resulting inflammatory response is believed to be involved in altered thermoregulation and multiple-organ dysfunction. Possible means for preventing or attenuating, or both, many stress-induced intestinal barrier problems include environmental, pharmaceutical, or nutritional approaches, or a combination of these.