The effects of moderate exercise on chronic stress-induced intestinal barrier dysfunction and antimicrobial defense

Irisin as an agent for protecting against osteoporosis: A review of the current mechanisms and pathways

BACKGROUND

Osteoporosis is recognized as a skeletal disorder characterized by diminished bone tissue quality and density. Regular physical exercise is widely acknowledged to preserve and enhance bone health, but the detailed molecular mechanisms involved remain unclear. Irisin, a factor derived from muscle during exercise, influences bone and muscle. Since its discovery in 2012, irisin has been found to promote bone growth and reduce bone resorption, establishing a tangible link between muscle exertion and bone health. Consequently, the mechanism by which irisin prevents osteoporosis have attracted significant scientific interest.

AIM OF THE REVIEW

This study aims to elucidate the multifaceted relationship between exercise, irisin, and bone health. Focusing on irisin, a muscle-derived factor released during exercise, we seek to understand its role in promoting bone growth and inhibiting resorption. Through a review of current research article on irisin in osteoporosis, Our review provides a deep dive into existing research on influence of irisin in osteoporosis, exploring its interaction with pivotal signaling pathways and its impact on various cell death mechanisms and inflammation. We aim to uncover the molecular underpinnings of how irisin, secreted during exercise, can serve as a therapeutic strategy for osteoporosis.

KEY SCIENTIFIC CONCEPTS OF THE REVIEW

Irisin, secreted during exercise, plays a vital role in bridging muscle function to bone health. It not only promotes bone growth but also inhibits bone resorption. Specifically, Irisin fosters osteoblast proliferation, differentiation, and mineralization predominantly through the ERK, p38, and AMPK signaling pathways. Concurrently, it regulates osteoclast differentiation and maturation via the JNK, Wnt/β-catenin and RANKL/RANK/OPG signaling pathways. This review further delves into the profound significance of irisin in osteoporosis and its involvement in diverse cellular death mechanisms, including apoptosis, autophagy, ferroptosis, and pyroptosis.

Intestinal barrier permeability: the influence of gut microbiota, nutrition, and exercise

The intestinal wall is a selectively permeable barrier between the content of the intestinal lumen and the internal environment of the body. Disturbances of intestinal wall permeability can potentially lead to unwanted activation of the enteric immune system due to excessive contact with gut microbiota and its components, and the development of endotoxemia, when the level of bacterial lipopolysaccharides increases in the blood, causing chronic low-intensity inflammation. In this review, the following aspects are covered: the structure of the intestinal wall barrier; the influence of the gut microbiota on the permeability of the intestinal wall via the regulation of functioning of tight junction proteins, synthesis/degradation of mucus and antioxidant effects; the molecular mechanisms of activation of the pro-inflammatory response caused by bacterial invasion through the TLR4-induced TIRAP/MyD88 and TRAM/TRIF signaling cascades; the influence of nutrition on intestinal permeability, and the influence of exercise with an emphasis on exercise-induced heat stress and hypoxia. Overall, this review provides some insight into how to prevent excessive intestinal barrier permeability and the associated inflammatory processes involved in many if not most pathologies. Some diets and physical exercise are supposed to be non-pharmacological approaches to maintain the integrity of intestinal barrier function and provide its efficient operation. However, at an early age, the increased intestinal permeability has a hormetic effect and contributes to the development of the immune system.

Citrus pectin protects mice from burn injury by modulating intestinal microbiota, GLP-1 secretion and immune response

Water-soluble rhamnogalacturonan-I enriched citrus pectin (WRP) has promising effect on antimicrobial defense. We aim to determine whether the modified acidic (A) or neutral (B) WRP solutions can improve intestinal microbial dysbiosis in burn-injured mice. Male Balb/c mice were gavaged with WRPs at 80, 160, 320 mg/kg. Body weight daily for 21 days before exposed to thermal injury of 15 % total body surface area and mortality was monitored. Mice with 80 mg/kg WRPs were also subjected to fecal DNAs and T cell metabonomics analysis, intestinal and plasma glucagon-like peptide 1 (GLP-1) detection, plasma defensin, immunoglobin and intestinal barrier examinations at 1 and 3d postburn (p.b.). Burn-induced mortality was only improved by low dose WRP-A (P = 0.039). Both WRPs could prevent the dysbiosis of gut microbiota in burn injury by reducing the expansion of inflammation-promoting bacteria. Both WRPs suppressed ileum GLP-1 production at 1d p.b. (P = 0.002) and plasma GLP-1 levels at 3d p.b. (P = 0.013). Plasma GLP-1 level correlated closely with ileum GLP-1 production (P = 0.019) but negatively with microbiota diversity at 1d p.b. (P = 0.003). Intestinal T cell number was increased by both WRPs in jejunum at 3d p.b. However, the exaggerated splenic T cell metabolism in burn injury was reversed by both WRPs at 1d p.b. The burn-increased plasma defensin β1 level was only reduced by WRP-B. Similarly, the intestinal barrier permeability was only rescued by WRP-B at 1d p.b. WRP-A rather than WRP-B could reduce burn-induced mortality in mice by suppressing intestinal GLP-1 secretion, restoring gut microbiota dysbiosis and improving adaptive immune response.

Intestinal Barrier Dysfunction and Gut Microbiota in Non-Alcoholic Fatty Liver Disease: Assessment, Mechanisms, and Therapeutic Considerations

Non-alcoholic fatty liver disease (NAFLD) is a type of metabolic stress liver injury closely related to insulin resistance (IR) and genetic susceptibility without alcohol consumption, which encompasses a spectrum of liver disorders ranging from simple hepatic lipid accumulation, known as steatosis, to the more severe form of steatohepatitis (NASH). NASH can progress to cirrhosis and hepatocellular carcinoma (HCC), posing significant health risks. As a multisystem disease, NAFLD is closely associated with systemic insulin resistance, central obesity, and metabolic disorders, which contribute to its pathogenesis and the development of extrahepatic complications, such as cardiovascular disease (CVD), type 2 diabetes mellitus, chronic kidney disease, and certain extrahepatic cancers. Recent evidence highlights the indispensable roles of intestinal barrier dysfunction and gut microbiota in the onset and progression of NAFLD/NASH. This review provides a comprehensive insight into the role of intestinal barrier dysfunction and gut microbiota in NAFLD, including intestinal barrier function and assessment, inflammatory factors, TLR4 signaling, and the gut-liver axis. Finally, we conclude with a discussion on the potential therapeutic strategies targeting gut permeability and gut microbiota in individuals with NAFLD/NASH, such as interventions with medications/probiotics, fecal transplantation (FMT), and modifications in lifestyle, including exercise and diet.

Atherosclerosis, gut microbiome, and exercise in a meta-omics perspective: a literature review

Background

Cardiovascular diseases are the leading cause of death worldwide, significantly impacting public health. Atherosclerotic cardiovascular diseases account for the majority of these deaths, with atherosclerosis marking the initial and most critical phase of their pathophysiological progression. There is a complex relationship between atherosclerosis, the gut microbiome's composition and function, and the potential mediating role of exercise. The adaptability of the gut microbiome and the feasibility of exercise interventions present novel opportunities for therapeutic and preventative approaches.

Methodology

We conducted a comprehensive literature review using professional databases such as PubMed and Web of Science. This review focuses on the application of meta-omics techniques, particularly metagenomics and metabolomics, in studying the effects of exercise interventions on the gut microbiome and atherosclerosis.

Results

Meta-omics technologies offer unparalleled capabilities to explore the intricate connections between exercise, the microbiome, the metabolome, and cardiometabolic health. This review highlights the advancements in metagenomics and metabolomics, their applications in research, and examines how exercise influences the gut microbiome. We delve into the mechanisms connecting these elements from a metabolic perspective. Metagenomics provides insight into changes in microbial strains post-exercise, while metabolomics sheds light on the shifts in metabolites. Together, these approaches offer a comprehensive understanding of how exercise impacts atherosclerosis through specific mechanisms.

Conclusions

Exercise significantly influences atherosclerosis, with the gut microbiome serving as a critical intermediary. Meta-omics technology holds substantial promise for investigating the gut microbiome; however, its methodologies require further refinement. Additionally, there is a pressing need for more extensive cohort studies to enhance our comprehension of the connection among these element.

Effects of different chronic restraint stress periods on anxiety- and depression-like behaviors and tryptophan-kynurenine metabolism along the brain-gut axis in C57BL/6N mice

Chronic restraint stress (CRS) is a widely used stimulus to induce anxiety- and depression-like behaviors, linked to alterations in tryptophan-kynurenine (TRP-KYN) metabolism in animals. This study assessed the effects of different CRS periods on anxiety- or depression-like behaviors and TRP-KYN metabolism along brain-gut axis in C57BL/6N mice. Results showed that one-week CRS decreased the open arm entries of mice in elevated plus maze and delayed latency of feeding in novelty suppressed feeding test. Four-week CRS reduced sucrose preference, increases forced swimming immobility time, and also induced anxiety-like behaviors of mice. UPLC-MS/MS analysis revealed decreased levels of the neurotoxic 3-hydroxykynurenine (3-HK) and quinolinic acid (QA), and an increase in the neuroprotective kynurenic acid (KA) in the hippocampus of one-week CRS mice; meanwhile, four-week CRS mice displayed a reduction in KA and increases in 3-HK and QA. In the colon, both one-week and four-week CRS mice exhibited significant reductions in 3-HK and QA, with a marked increase of KA exclusively in four-week CRS mice. Briefly, one-week CRS only induced anxiety-like behaviors with hippocampal neuroprotection in TRP-KYN metabolism, whereas four-week CRS caused anxiety- and depression-like behaviors with neurotoxicity. In the colon, during both CRS periods, KYN was metabolized in the direction of NAD+ production. However, four-week CRS triggered intestinal inflammation risk with increased KA. Summarily, slightly short-term stress has beneficial effects on mice, while prolonged chronic stress can lead to pathological changes. This study offers valuable insights into stress-induced emotional disturbances.

A Sedentary Lifestyle Changes the Composition and Predicted Functions of the Gut Bacterial and Fungal Microbiota of Subjects from the Same Company

A sedentary lifestyle affects the diversity and composition of the gut microbiota, but previous studies have mainly focused on bacteria instead of fungi. Here, we compared both the fecal bacterial and fungal microbiota compositions and functions in sedentary persons and controls. Subjects from the China Railway Corporation, including 99 inspectors and 88 officials, were enrolled in our study. Fecal microbiota communities were analyzed using 16S rRNA gene sequencing for bacteria and ITS sequencing for fungi. We found that the diversity of the gut microbiota of the sedentary group was significantly lower than that of the control group (P < 0.05). The sedentary group had a higher abundance of Firmicutes, a lower abundance of Actinobacteria and Proteobacteria and a higher abundance of Ascomycota, and a lower abundance of Basidiomycota. Furthermore, functional prediction analysis of the fungal microbiota revealed more L-tryptophan degradation to 2-amino-3-carboxymuconate semialdehyde, more phospholipid remodeling (phosphatidylethanolamine, yeast), and more L-tyrosine degradation I, as well as less pentose phosphate pathway (non-oxidative branch), less adenosine nucleotide biosynthesis and less L-valine biosynthesis in the sedentary group (P < 0.05). Thus, a sedentary lifestyle changes the composition and function of the gut microbiota. It may change the pentose phosphate pathway (non-oxidative branch), nucleic acid and amino acid biosynthesis and phospholipid metabolism in fungi.

Sex-specific effects of voluntary wheel running on behavior and the gut microbiota-immune-brain axis in mice

Physical exercise has been positioned as a promising strategy to prevent and/or alleviate anxiety and depression, but the biological processes associated with its effects on mental health have yet to be entirely determined. Although the prevalence of depression and anxiety in women is about twice that of men, very few studies have examined whether physical exercise could affect mental health differently according to sex. This study examined, in singly-housed mice, the sex-specific effects of voluntary exercise on depressive- and anxiety-like behaviors as well as on different markers along the gut microbiota-immune-brain axis. Male and female C57BL/6N mice had voluntary access to running wheels in their home-cages for 24 days or were left undisturbed in identical home-cages without running wheels. Behaviors were then examined in the open field, splash, elevated plus maze, and tail suspension tests. Gene expression of pro-inflammatory cytokines, microglia activation-related genes, and tight junction proteins was determined in the jejunum and the hippocampus, while microbiota composition and predicted function were verified in cecum contents. Voluntary exercise reduced anxiety-like behaviors and altered grooming patterns in males exclusively. Although the exercise intervention resulted in changes to brain inflammatory activity and to cecal microbiota composition and inferred function in both sexes, reductions in the jejunal expression of pro-inflammatory markers were observed in females only. These findings support the view that voluntary exercise, even when performed during a short period, is beneficial for mental and intestinal health and that its sex-specific effects on behavior could be, at least in part, related to some components of the gut microbiota-immune-brain axis.

Effects of urbanization and lifestyle habits on the intestinal microbiota of adolescents in eastern China

Introduction

Owing to urbanization, living habits have changed widely, leading to alterations in the intestinal microbiota of urban residents. However, there are few studies on the characteristics of intestinal microbiota of adolescents living in different urbanized areas in China.

Methods

A total of 302 fecal samples collected from adolescent students in eastern China were examined. 16S rRNA high-throughput sequencing was used to identify the fecal microbiota. These data were combined with questionnaire survey results to investigate the effect of urbanization on the intestinal microbiota of adolescents in eastern China. Moreover, the role of lifestyle habits in this relationship was also evaluated.

Results

The results revealed significant differences in the structure of the intestinal microbiota among adolescents living in regions with different levels of urbanization. Adolescents living in urban regions had a significantly higher proportion of Bacteroides (p <  0.001, FDR = 0.004), whereas those living in towns and rural regions had higher proportions of Bifidobacterium (p < 0.001, FDR < 0.001) and Prevotella (p  < 0.05, FDR = 0.019). The diversity of the intestinal microbiota was higher in urban residents than in adolescents living in towns and rural regions (p  <  0.05). In addition, the differences in intestinal microbiota across individuals living in cities, towns, and rural regions were related to dietary preferences, flavor preferences, and sleep and exercise durations. Adolescents who ate more meat had more Dorea (LDA = 3.622, p = 0.04), while the abundance of Escherichia-Shigella is higher among adolescents who ate more condiments (LDA = 4.285, p = 0.02). The abundance of Dialister was significantly increased in adolescents with longer sleep durations (LDA = 4.066, p = 0.03). Adolescents who exercised for a long duration had more Faecalibacterium than those who exercised for a shorter duration (LDA = 4.303, p = 0.04).

Discussion

Our research has preliminarily demonstrated that there were differences in the composition of Gut microbiome in stool samples of adolescents living in different urbanized areas, and provide a scientific basis for the maintenance of a healthy intentional microbota in adolescences.

Combined Physical Exercise and Diet: Regulation of Gut Microbiota to Prevent and Treat of Metabolic Disease: A Review

BACKGROUND

Unhealthy diet and sedentary lifestyle have contributed to the rising incidence of metabolic diseases, which is also accompanied by the shifts of gut microbiota architecture. The gut microbiota is a complicated and volatile ecosystem and can be regulated by diet and physical exercise. Extensive research suggests that diet alongside physical exercise interventions exert beneficial effects on metabolic diseases by regulating gut microbiota, involving in the changes of the energy metabolism, immune regulation, and the microbial-derived metabolites.

OBJECTIVE

In this review, we present the latest evidence in the modulating role of diet and physical exercise in the gut microbiota and its relevance to metabolic diseases. We also summarize the research from animal and human studies on improving metabolic diseases through diet-plus-exercise interventions, and new targeted therapies that might provide a better understanding of the potential mechanisms.

METHODS

A systematic and comprehensive literature search was performed in PubMed/Medline and Web of Science in October 2022. The key terms used in the searches included "combined physical exercise and diet", "physical exercise, diet and gut microbiota", "physical exercise, diet and metabolic diseases" and "physical exercise, diet, gut microbiota and metabolic diseases".

CONCLUSIONS

Combined physical exercise and diet offer a more efficient approach for preventing metabolic diseases via the modification of gut microbiota, abating the burden related to longevity.

A narrative review of the moderating effects and repercussion of exercise intervention on osteoporosis: ingenious involvement of gut microbiota and its metabolites

Osteoporosis (OP) is a systemic bone disease characterized by the decreased bone mass and destruction of bone microstructure, which tends to result in the enhanced bone fragility and related fractures, as well as high disability rate and mortality. Exercise is one of the most common, reliable and cost-effective interventions for the prevention and treatment of OP currently, and numerous studies have revealed the close association between gut microbiota (GM) and bone metabolism recently. Moreover, exercise can alter the structure, composition and abundance of GM, and further influence the body health via GM and its metabolites, and the changes of GM also depend on the choice of exercise modes. Herein, combined with relevant studies and based on the inseparable relationship between exercise intervention-GM-OP, this review is aimed to discuss the moderating effects and potential mechanisms of exercise intervention on GM and bone metabolism, as well as the interaction between them.

The Emerging Role of the Aging Process and Exercise Training on the Crosstalk between Gut Microbiota and Telomere Length

Aging is a natural process of organism deterioration, which possibly impairs multiple physiological functions. These harmful effects are linked to an accumulation of somatic mutations, oxidative stress, low-grade inflammation, protein damage, and mitochondrial dysfunction. It is known that these factors are capable of inducing telomere shortening, as well as intestinal dysbiosis. Otherwise, among the biological mechanisms triggered by physical exercise, the attenuation of pro-inflammatory mediators accompanied by redox state improvement can be the main mediators for microbiota homeostasis and telomere wear prevention. Thus, this review highlights how oxidative stress, inflammation, telomere attrition, and gut microbiota (GM) dysbiosis are interconnected. Above all, we provide a logical foundation for unraveling the role of physical exercise in this process. Based on the studies summarized in this article, exercise training can increase the biodiversity of beneficial microbial species, decrease low-grade inflammation and improve oxidative metabolism, these factors together possibly reduce telomeric shortening.

Examining the cognitive benefits of probiotic supplementation in physically active older adults: A randomized clinical trial

The prevalence of dementia is projected to increase with the growing older adult population and prevention strategies are urgently needed. Two promising interventions include physical activity (PA) and probiotic supplementation, with initial findings suggesting their combined use may confer greater cognitive benefits than either intervention alone. However, no study has yet examined the effects of probiotic supplementation on cognitive function in healthy, physically active older adults. The present study used archival data from a randomized clinical trial including 127 physically active, middle-aged to older adults (avg age 64.3 years) with self-reported PA levels meeting or exceeding recommendations to investigate the effects of probiotic supplementation (Lactobacillus rhamnosus GG; L.GG) on cognitive outcomes. Repeated measures ANOVAs showed no significant changes in cognitive performance from baseline to follow up as an effect of L.GG consumption. These results suggest that probiotic supplementation may not improve cognitive function in persons already engaged in high levels of PA. Future research should include prospective studies to determine whether long-term use of probiotic supplementation may help prevent cognitive decline. Novelty: • Initial research shows promising cognitive benefits of combined physical activity and probiotics consumption. • L.GG did not lead to acute cognitive improvements for older adults already meeting physical activity guidelines. • Prospective studies examining prevention of cognitive decline with probiotics in healthy and clinical samples are much needed.

Rethinking Parkinson Disease: Exploring Gut-Brain Interactions and the Potential Role of Exercise

Although Parkinson disease (PD) has traditionally been considered a disease of the central nervous system, a bidirectional communication system known as the gut-brain axis can influence PD pathogenesis. The dual-hit hypothesis proposed that PD is due to peripheral dysregulations to the gut microbiota, known as dysbiosis. Since then, further investigation has shown that there are multiple pathological sources associated with PD. However, dysbiosis plays a critical role in the disease process. Substantial evidence has identified that cardinal motor symptoms of PD and disease progression are associated with dysbiosis. In other neurodegenerative disorders, dysbiosis has been linked to cognition. Non-PD research has shown that exercise can effectively restore the gut microbiota. Likewise, exercise has become a well-established strategy to improve cognitive and motor function in PD. However, despite the interaction between the gut and brain, and the exercise benefits on gut health, no research to date has considered the effects of exercise on the gut microbiota in PD. Therefore, the purpose of this Perspective is to explore whether exercise benefits observed in PD could partly be due to restorations to the gut microbiota. First, we will review the gut-brain axis and its influence on motor and cognitive function. Next, we will outline evidence regarding exercise-induced restoration of the gut microbiota in non-PD populations. Finally, we will summarize benefits of exercise on motor-cognitive function in PD, proposing that benefits of exercise seen in PD might actually be due to restorations to the gut microbiota. By positing the gut microbiota as a moderator of exercise improvements to motor and cognitive function, we aim to provide a new perspective for physical therapists to prioritize exercise regimens for individuals with PD that can specifically restore the gut microbiota to better improve PD symptoms and prognosis.

IMPACT

This Perspective raises awareness that dysregulations to the gut microbiota have recently been attributed to PD symptoms and pathology and that exercise can be an effective therapeutic strategy to improve gut health in individuals with PD.

LAY SUMMARY

People with PD have been found to have reduced microbial diversity in their gut, which can play an important role in the progression of the disease. Physical therapists can design therapeutic exercises that might help improve gut health in people with PD.

Exercise alleviated intestinal damage and microbial disturbances in mice exposed to fluoride

Gastrointestinal reaction is an important symptom of fluorosis and is associated with intestinal morphological and functional impairment. Regular moderate exercise may reduce the incidence of infection and contribute to the maintenance of intestinal mucosal function and immune homeostasis. In this study, the mice were randomly divided to four groups: control group (C, distilled water), exercise group (E, distilled water and treadmill exercise), fluoride group (F, 100 mg/L NaF), and exercise plus fluoride group (EF, 100 mg/L NaF and treadmill exercise). The treadmill exercise was performed as 5 m/min, 5 min; 10 or 12 m/min, 20 min; 5 m/min, 5 min, with 5 consecutive days per week. After 6 months, exercise alleviated the intestinal morphological structure damage and restored the villus height (VH) and VH/crypt depth (VH/CD) in the duodenum of fluoride-exposed mice. Exercise decreased the mRNA expressions of IL-1β, IL-6, TNF-α, TLR2 and NF-κB (p65) in fluoride-exposed mice, and restored the gene levels of Occludin and ZO-1 in the duodenum, as well as Occludin, ZO-1, and Claudin-1 in the colon. Although there were no significant differences in the Occludin and ZO-1 protein expressions between F and EF, two proteins in EF presented statistical homogeneousness when compared with the C. The 16S rDNA high-throughput sequencing found that exercise restored the variations in intestinal microbiota composition and the abundances of specific bacteria in fluoride-exposed mice, including increasing the abundances of Epsilonbacteraenta and Firmicutes, reducing the Bacteroidetes abundance at the phylum level, and restoring the abundances of 13 bacterial genera. In conclusion, exercise improved intestinal morphological structure damage in fluoride-exposed mice, inhibited the secretion of duodenal inflammatory factors, increased the expression of tight junctions, and alleviated the microbial disorder in mice caused by fluoride exposure for 6 months through actively regulating the composition of intestinal microorganisms and the abundance of specific bacteria.

The active grandparent hypothesis: Physical activity and the evolution of extended human healthspans and lifespans

The proximate mechanisms by which physical activity (PA) slows senescence and decreases morbidity and mortality have been extensively documented. However, we lack an ultimate, evolutionary explanation for why lifelong PA, particularly during middle and older age, promotes health. As the growing worldwide epidemic of physical inactivity accelerates the prevalence of noncommunicable diseases among aging populations, integrating evolutionary and biomedical perspectives can foster new insights into how and why lifelong PA helps preserve health and extend lifespans. Building on previous life-history research, we assess the evidence that humans were selected not just to live several decades after they cease reproducing but also to be moderately physically active during those postreproductive years. We next review the longstanding hypothesis that PA promotes health by allocating energy away from potentially harmful overinvestments in fat storage and reproductive tissues and propose the novel hypothesis that PA also stimulates energy allocation toward repair and maintenance processes. We hypothesize that selection in humans for lifelong PA, including during postreproductive years to provision offspring, promoted selection for both energy allocation pathways which synergistically slow senescence and reduce vulnerability to many forms of chronic diseases. As a result, extended human healthspans and lifespans are both a cause and an effect of habitual PA, helping explain why lack of lifelong PA in humans can increase disease risk and reduce longevity.

Irisin attenuates inflammation in a mouse model of ulcerative colitis by altering the intestinal microbiota

Evidence has demonstrated that the gut microbiota, which consists of probiotics and pathogenic microorganisms, is involved in the initiation of ulcerative colitis (UC) via the dysregulation of intestinal microflora and normal immune interactions, which ultimately leads to intestinal mucosal dysfunction. Irisin is released from muscle cells and displays anti-inflammatory effects; however, the mechanisms underlying irisin-mediated anti-inflammatory effects in UC have not been previously reported. In the present study, mice were divided into the following four groups: i) Control; ii) irisin; iii) dextran sulfate sodium (DSS) salt; and iv) DSS + irisin. Subsequently, the effects of irisin were investigated by observing alterations in intestinal microbes. Irisin significantly reduced the degree of inflammation in UC by reversing alterations to the macroscopic score, histological score, number of CD64⁺ cells and inflammatory cytokine alterations (P<0.05). Analysis of the microbial diversity in the stools of mice with active UC indicated that the five bacteria that displayed the greatest alterations in relative abundance were Alloprevotella, Bacteroides, Lachnospiraceae-UCG-001, Prebotellaceae-UCG-001 and Rikenellaceae-RCB-gut-group. Furthermore, Bactoroides were positively correlated with the histopathological score (P=0.001; R=0.977) and interleukin (IL)-23 levels (P=0.008; R=0.924). Alloprevotella (P=0.001; R=-0.943), Lachnospiraceae-UCG-001 (P=0.000; R=-0.973) and Rikenollaceae-RC8-gut-group (P=0.001; R=-0.971) were negatively correlated with the histopathological score. Furthermore, Lachnospiraceae-UCG-001 (P=0.01; R=-0.873) and Rikenollaceae-RC8-gut-group (P=0.049; R=-0.814) were negatively correlated with IL-23 levels. In summary, the results of the present study suggested that irisin improved inflammation in a UC mouse model potentially via altering the gut microbiota.

Beyond the Finish Line: The Impact and Dynamics of Biomarkers in Physical Exercise-A Narrative Review

The research of biomarkers continues to emerge as a developing academic field which is attracting substantial interest. The study of biomarkers proves to be useful in developing and implementing new screening methods for a wide variety of diseases including in the sports area, whether for leisure activities or professional sports. Novel research has brought into question the immune system and the limitations it may impose on sports practicing. As the well-being of athletes is a priority, the state of their immune function offers valuable information regarding their health status and their ability to continue training. The assessment of various biomarkers may contribute to a more accurate risk stratification and subsequent prevention of some invalidating or even fatal pathologies such as the sudden cardiac death. Therefore, we have reviewed several studies that included sports-related pathology or specific morphofunctional alterations for which some immune biomarkers may represent an expression of the underlying mechanism. These include the defensins, immunoglobulin A (IgA), interleukin-6 (IL-6), the tumoral necrosis factor α (TNF-α), and the white blood cells (WBC) count. Similarly, also of significant interest are various endocrine biomarkers, such as cortisol and testosterone, as well as anabolic or catabolic markers, respectively. Literature data highlight that these values are greatly influenced not only by the duration, but also by the intensity of the physical exercise; moderate training sessions actually enhance the immune function of the body, while a significant increase in both duration and intensity of sports activity acts as a deleterious factor. Therefore, in this paper we aim to highlight the importance of biomarkers’ evaluation in connection with sports activities and a subsequent more adequate approach towards personalized training regimens.

A next-generation probiotic: Akkermansia muciniphila ameliorates chronic stress-induced depressive-like behavior in mice by regulating gut microbiota and metabolites

Major depressive disorder (MDD) is a neurasthenic disease, which is the second-largest burden of disease globally. Increasing studies have revealed that depression is associated with abnormalities in gut microbiota and metabolites. Several species of bacteria have been classified as psychobiotics, which confer mental health benefits through interactions with commensal gut microbiota. Therefore, it is essential to identify new psychobiotics and elucidate their mechanisms in the treatment of depression. This study aims to evaluate the antidepressant effect of Akkermansia muciniphila (AKK) in a mouse model of depression induced by chronic restraint stress (CRS). C57BL/6 male mice were divided into three groups: mice subjected to CRS, mice not subjected to CRS, and mice treated with AKK for 3 weeks. Behavioral tests were performed, and hormone, neurotransmitter, and brain-derived neurotrophic factor (BDNF) levels were measured. Cecal microbiota was analyzed using 16S rRNA gene sequencing, and serum metabolites were detected using untargeted metabolomics. In addition, correlations between altered gut microbiota and metabolites with significant variations in serum associated with AKK ameliorating depression were analyzed using Pearson's correlation coefficient. The results revealed that AKK significantly ameliorated depressive-like behavior and restored abnormal variations in depression-related molecular (corticosterone, dopamine, and BDNF). Moreover, AKK altered chronic stress-induced gut microbial abnormalities. Untargeted metabolomics analysis revealed 23 potential biomarkers in serum that could be associated with the mechanisms underlying CRS-induced depression and the therapeutic effects of AKK. Pearson's correlation coefficient analysis revealed that AKK predominantly upregulated β-alanyl-3-methyl-L-histidine and edaravone to relieve depression. Furthermore, β-alanyl-3-methyl-L-histidine and edaravone exhibited the antidepressant phenotype in mice subjected to CRS. In conclusion, the study demonstrated that AKK ameliorates chronic stress-induced depressive symptoms in mice by regulating gut microbiota and metabolites. KEY POINTS: • AKK reduces depressive-like behaviors induced by chronic stress. • AKK regulates the gut microbial structure and metabolomics of serum under the chronic stress. • Antidepressant effect of AKK correlates with the increase of β-alanyl-3-methyl-l-histidine and edaravone.

A Microbiome-Driven Approach to Combating Depression During the COVID-19 Pandemic

The significant stressors brought about and exacerbated by COVID-19 are associated with startling surges in mental health illnesses, specifically those related to depressive disorders. Given the huge impact of depression on society, and an incomplete understanding of impactful therapeutics, we have examined the current literature surrounding the microbiome and gut-brain axis to advance a potential complementary approach to address depression and depressive disorders that have increased during the COVID-19 pandemic. While we understand that the impact of the human gut microbiome on emotional health is a newly emerging field and more research needs to be conducted, the current evidence is extremely promising and suggests at least part of the answer to understanding depression in more depth may lie within the microbiome. As a result of these findings, we propose that a microbiome-based holistic approach, which involves carefully annotating the microbiome and potential modification through diet, probiotics, and lifestyle changes, may address depression. This paper's primary purpose is to shed light on the link between the gut microbiome and depression, including the gut-brain axis and propose a holistic approach to microbiome modification, with the ultimate goal of assisting individuals to manage their battle with depression through diet, probiotics, and lifestyle changes, in addition to offering a semblance of hope during these challenging times.

Is There an Exercise-Intensity Threshold Capable of Avoiding the Leaky Gut?

Endurance-sport athletes have a high incidence of gastrointestinal disorders, compromising performance and impacting overall health status. An increase in several proinflammatory cytokines and proteins (LPS, I-FABP, IL-6, IL-1β, TNF-α, IFN-γ, C-reactive protein) has been observed in ultramarathoners and triathlon athletes. One of the most common effects of this type of physical activity is the increase in intestinal permeability, known as leaky gut. The intestinal mucosa's degradation can be identified and analyzed by a series of molecular biomarkers, including the lactulose/rhamnose ratio, occludin and claudin (tight junctions), lipopolysaccharides, and I-FABP. Identifying the molecular mechanisms involved in the induction of leaky gut by physical exercise can assist in the determination of safe exercise thresholds for the preservation of the gastrointestinal tract. It was recently shown that 60 min of vigorous endurance training at 70% of the maximum work capacity led to the characteristic responses of leaky gut. It is believed that other factors may contribute to this effect, such as altitude, environmental temperature, fluid restriction, age and trainability. On the other hand, moderate physical training and dietary interventions such as probiotics and prebiotics can improve intestinal health and gut microbiota composition. This review seeks to discuss the molecular mechanisms involved in the intestinal mucosa's adaptation and response to exercise and discuss the role of the intestinal microbiota in mitigating these effects.

High-Intensity Interval Training and α-Linolenic Acid Supplementation Improve DHA Conversion and Increase the Abundance of Gut Mucosa-Associated Oscillospira Bacteria

Obesity, a major public health problem, is the consequence of an excess of body fat and biological alterations in the adipose tissue. Our aim was to determine whether high-intensity interval training (HIIT) and/or α-linolenic acid supplementation (to equilibrate the n-6/n-3 polyunsaturated fatty acids (PUFA) ratio) might prevent obesity disorders, particularly by modulating the mucosa-associated microbiota. Wistar rats received a low fat diet (LFD; control) or high fat diet (HFD) for 16 weeks to induce obesity. Then, animals in the HFD group were divided in four groups: HFD (control), HFD + linseed oil (LO), HFD + HIIT, HFD + HIIT + LO. In the HIIT groups, rats ran on a treadmill, 4 days.week^-1. Erythrocyte n-3 PUFA content, body composition, inflammation, and intestinal mucosa-associated microbiota composition were assessed after 12 weeks. LO supplementation enhanced α-linolenic acid (ALA) to docosahexaenoic acid (DHA) conversion in erythrocytes, and HIIT potentiated this conversion. Compared with HFD, HIIT limited weight gain, fat mass accumulation, and adipocyte size, whereas LO reduced systemic inflammation. HIIT had the main effect on gut microbiota β-diversity, but the HIIT + LO association significantly increased Oscillospira relative abundance. In our conditions, HIIT had a major effect on body fat mass, whereas HIIT + LO improved ALA conversion to DHA and increased the abundance of Oscillospira bacteria in the microbiota.

Cancer Related Anemia: An Integrated Multitarget Approach and Lifestyle Interventions

Cancer is often accompanied by worsening of the patient's iron profile, and the resulting anemia could be a factor that negatively impacts antineoplastic treatment efficacy and patient survival. The first line of therapy is usually based on oral or intravenous iron supplementation; however, many patients remain anemic and do not respond. The key might lie in the pathogenesis of the anemia itself. Cancer-related anemia (CRA) is characterized by a decreased circulating serum iron concentration and transferrin saturation despite ample iron stores, pointing to a more complex problem related to iron homeostatic regulation and additional factors such as chronic inflammatory status. This review explores our current understanding of iron homeostasis in cancer, shedding light on the modulatory role of hepcidin in intestinal iron absorption, iron recycling, mobilization from liver deposits, and inducible regulators by infections and inflammation. The underlying relationship between CRA and systemic low-grade inflammation will be discussed, and an integrated multitarget approach based on nutrition and exercise to improve iron utilization by reducing low-grade inflammation, modulating the immune response, and supporting antioxidant mechanisms will also be proposed. Indeed, a Mediterranean-based diet, nutritional supplements and exercise are suggested as potential individualized strategies and as a complementary approach to conventional CRA therapy.

Exercise and intestinal permeability: another form of exercise-induced hormesis?

Regular aerobic exercise has numerous benefits on human physiology, arguably by serving as a hormetic stressor resulting in positive adaptations over time. It has long been known that aerobic exercise at a variety of intensities and durations induces intestinal permeability, which is a feature of many pathologies of the gastrointestinal tract and metabolic diseases. Given the health benefits of exercise, it seems unlikely that intestinal permeability induced by exercise outweighs the positive adaptations. In fact, a growing body of evidence suggests adoption of exercise regimens lasting weeks to months improves indicators of intestinal permeability. In this brief review, we summarize factors contributing to acute exercise-induced intestinal permeability and what is known about chronic exercise and the gut barrier. Additionally, we outline known and theoretical adaptations of the gut to chronic exercise that may explain emerging reports that exercise improves markers of gut integrity.

The Potential Mediation of the Effects of Physical Activity on Cognitive Function by the Gut Microbiome

The population of older adults is growing dramatically worldwide. As older adults are at greater risk of developing disorders associated with cognitive dysfunction (i.e., dementia), healthcare costs are expected to double by 2040. Evidence suggests dementia may be slowed or prevented by lifestyle interventions, including physical activity (PA). PA is associated with improved cognitive function and may reduce risk for dementia by mitigating known risk factors (i.e., cardiovascular diseases) and/or by enhancing neurochemical processes. An emerging area of research suggests the gut microbiome may have similar neuroprotective effects. Altering the gut microbiome has been found to target physiological processes associated with dementia risk, and it influences gut-brain-microbiome axis signaling, impacting cognitive functioning. The gut microbiome can be altered by several means (i.e., disease, diet, prebiotics, probiotics), including PA. As PA and the gut microbiome independently influence cognitive function and PA changes the composition of the gut microbiome, cognitive improvement due to PA may be partially mediated by the gut microbiome. The present article provides an overview of the literature regarding the complex associations among PA, cognitive function, and the gut microbiome, as well as their underlying biological mechanisms. A comprehensive, theoretical model integrating evidence for the potential mediation is proposed.

Exercise Preconditioning Attenuates the Response to Experimental Colitis and Modifies Composition of Gut Microbiota in Wild-Type Mice

This study investigated the suppressive effect of exercise preconditioning against colitis induced by high-fat diet (HF) plus dextran sulfate sodium (DSS) in wild-type mice. Male mice (C57BL/6) aged 6 weeks were assigned to standard chow (SC, n = 10) or HF (n = 10) or HF followed by DSS (HF+DSS, n = 10) or exercise preconditioning (EX) followed by HF+DSS (EX+HF+DSS, n = 10) for a total of 15 weeks. After 12 weeks of dietary treatments and/or exercise preconditioning, mice in the DSS groups were subjected to administration of 2 cycles of 5-day DSS (2% w/v) with a 7-day interval between cycles. HF resulted in colitis symptoms and histological changes, infiltration of immunity cells, decreased gut barrier proteins, increased pro-inflammatory and chemotactic cytokines and decreased anti-inflammatory cytokine such as adiponectin, which deteriorated after administration of DSS. Exercise preconditioning alleviated HF+DSS-induced colitis and caused significant modifications in gut microbiota: decreased Bacteroides vulgatus (p = 0.050) and increased Akkermansia muciniphila (p = 0.050). The current findings suggest that exercise preconditioning attenuates the severity of HF+DSS-induced colitis in C57BL/6 mice.

Anti-stress effects of rosemary (Rosmarinus officinalis L.) leaf extract on intestinal goblet cells and immobility of forced-swimming test in BALB/c mice

We investigated the anti-stress effect of rosemary (Rosmarinus officinalis L.) leaf extract (RLE) on restraint-stressed mice and found that RLE alleviated decreases in the number of intestinal goblet cells and amount of hepatic triglycerides. It also decreased the immobility time in the forced-swimming test and activation of microglia in the brain, suggesting that RLE has beneficial effects on stress-induced dysfunctions.

Microbiota and Lifestyle: A Special Focus on Diet

It is widely known that a good balance and healthy function for bacteria groups in the colon are necessary to maintain homeostasis and preserve health. However, the lack of consensus on what defines a healthy gut microbiota and the multitude of factors that influence human gut microbiota composition complicate the development of appropriate dietary recommendations for our gut microbiota. Furthermore, the varied response to the intake of probiotics and prebiotics observed in healthy adults suggests the existence of potential inter- and intra-individual factors, which might account for gut microbiota changes to a greater extent than diet. The changing dietary habits worldwide involving consumption of processed foods containing artificial ingredients, such as sweeteners; the coincident rise in emotional disorders; and the worsening of other lifestyle habits, such as smoking habits, drug consumption, and sleep, can together contribute to gut dysbiosis and health impairment, as well as the development of chronic diseases. This review summarizes the current literature on the effects of specific dietary ingredients (probiotics, prebiotics, alcohol, refined sugars and sweeteners, fats) in the gut microbiota of healthy adults and the potential inter- and intra-individual factors involved, as well as the influence of other potential lifestyle factors that are dramatically increasing nowadays.

The athletic gut microbiota

The microorganisms in the gastrointestinal tract play a significant role in nutrient uptake, vitamin synthesis, energy harvest, inflammatory modulation, and host immune response, collectively contributing to human health. Important factors such as age, birth method, antibiotic use, and diet have been established as formative factors that shape the gut microbiota. Yet, less described is the role that exercise plays, particularly how associated factors and stressors, such as sport/exercise-specific diet, environment, and their interactions, may influence the gut microbiota. In particular, high-level athletes offer remarkable physiology and metabolism (including muscular strength/power, aerobic capacity, energy expenditure, and heat production) compared to sedentary individuals, and provide unique insight in gut microbiota research. In addition, the gut microbiota with its ability to harvest energy, modulate the immune system, and influence gastrointestinal health, likely plays an important role in athlete health, wellbeing, and sports performance. Therefore, understanding the mechanisms in which the gut microbiota could play in the role of influencing athletic performance is of considerable interest to athletes who work to improve their results in competition as well as reduce recovery time during training. Ultimately this research is expected to extend beyond athletics as understanding optimal fitness has applications for overall health and wellness in larger communities. Therefore, the purpose of this narrative review is to summarize current knowledge of the athletic gut microbiota and the factors that shape it. Exercise, associated dietary factors, and the athletic classification promote a more “health-associated” gut microbiota. Such features include a higher abundance of health-promoting bacterial species, increased microbial diversity, functional metabolic capacity, and microbial-associated metabolites, stimulation of bacterial abundance that can modulate mucosal immunity, and improved gastrointestinal barrier function.

Nonalcoholic Fatty Liver Disease: Modulating Gut Microbiota to Improve Severity?

Gut microbiota plays a role in the pathophysiology of metabolic diseases, which include nonalcoholic fatty liver diseases, through the gut-liver axis. To date, clinical guidelines recommend a weight loss goal of 7%-10% to improve features of nonalcoholic fatty liver diseases. Because this target is not easily achieved by all patients, alternative therapeutic options are currently being evaluated. This review focuses on therapeutics that aim to modulate the gut microbiota and the gut-liver axis. We discuss how probiotics, prebiotics, synbiotic, fecal microbiota transfer, polyphenols, specific diets, and exercise interventions have been found to modify gut microbiota signatures; improve nonalcoholic fatty liver disease outcomes; and detail, when available, the different mechanisms by which these beneficial outcomes might occur. Apart from probiotics that have already been tested in human randomized controlled trials, most of these potential therapeutics have been studied in animals. Their efficacy still warrants confirmation in humans using appropriate design.

The Synergistic Role of Diet and Exercise in the Prevention, Pathogenesis, and Management of Ulcerative Colitis: An Underlying Metabolic Mechanism

Ulcerative colitis (UC) is a biologically complex condition characterized by chronic, relapsing inflammation of the gastrointestinal tract. The relative incidence of this debilitating condition is increasing and sociologically damaging outcomes are a continued reality. Several etiological theories for UC are currently under investigation, spanning between genetic and environmental determinants. From an environmental perspective, previous literature reviews have demonstrated the independent effectiveness of specific diet and exercise patterns in modifying UC immuno-pathophysiology. This article explores the synergistic role of diet and aerobic exercise in the prevention, pathogenesis, and management of UC in the context of recent immunological research. Through a unifying mechanism-that is, microbial influence of colonic inflammation and immuno-pathophysiology-the simultaneous reduction of pro-inflammatory dietary sulfurous amino acid intake (ie methionine, cysteine, homocysteine, and taurine) and the upregulation of aerobic exercise frequency (which spurs the colonization of anti-inflammatory butyrate, acetate, and propionate producing microbial taxa) demonstrate the clinical efficacy of incorporating both diet and exercise modifications for UC prevention and management through pathogenic alterations.

Effects of Exercise on Stress-induced Attenuation of Vaccination Responses in Mice

Studies suggest that exercise can improve vaccination responses in humans. Chronic stress can lead to immunosuppression, and there may be a role for exercise in augmenting immune responses.

PURPOSE

To investigate the effects of acute eccentric exercise (ECC) and voluntary wheel exercise training (VWR) on antibody and cell-mediated immune responses to vaccination in chronically stressed mice. We hypothesized that both ECC and VWR would attenuate chronic stress-induced reductions in vaccination responses.

METHODS

Mice were randomized into four groups: control (CON), stress (S)-ECC, S-VWR, and S-sedentary (SED). Stressed groups received chronic restraint stress for 6 h·d, 5 d·wk for 3 wk. After the first week of stress, S-ECC were exercised at 17 m·min speed at -20% grade for 45 min on a treadmill and then intramuscularly injected with 100 μg of ovalbumin (OVA) and 200 μg of alum adjuvant. All other groups were also vaccinated at this time. Stress-VWR mice voluntarily ran on a wheel for the entire experiment. Plasma was collected before, and at 1, 2, and 4 wk postvaccination. Enzyme-linked immunosorbent assay was performed to analyze anti-OVA IgG and IgM antibodies. After 3 wk of chronic stress, all mice were injected with OVA into the ear to determine the delayed-type hypersensitivity.

RESULTS

We found that chronic restraint stress significantly reduced body weight and caused adrenal hypertrophy. We also found both S-ECC and S-VWR groups had significantly elevated anti-OVA IgG (P < 0.05), whereas no significant differences between the two exercise groups. Neither S-ECC nor S-VWR altered anti-OVA IgM or delayed-type hypersensitivity responses compared with S-SED group.

CONCLUSIONS

Acute eccentric exercise and voluntary exercise training alleviated the chronic stress-induced anti-OVA IgG reductions in vaccination responses.

Ginseng oligopeptides protect against irradiation-induced immune dysfunction and intestinal injury

Intestinal injury and immune dysfunction are commonly encountered after irradiation therapy. While the curative abilities of ginseng root have been reported in prior studies, there is little known regarding its role in immunoregulation of intestinal repairability in cancer patients treated with irradiation. Our current study aims to closely examine the protective effects of ginseng-derived small molecule oligopeptides (Panax ginseng C. A. Mey.) (GOP) against irradiation-induced immune dysfunction and subsequent intestinal injury, using in vitro and in vivo models. Expectedly, irradiation treatment resulted in increased intestinal permeability along with mucosal injury in both Caco-2 cells and mice, probably due to disruption of the intestinal epithelial barrier, leading to high plasma lipopolysaccharide (LPS) and pro-inflammatory cytokines levels. However, when the cells were treated with GOP, this led to diminished concentration of plasma LPS and cytokines (IL-1 and TNF-α), suggesting its dampening effect on inflammatory and oxidative stress, and potential role in restoring normal baseline intestinal permeability. Moreover, the Caco-2 cells treated with GOP showed high trans-epithelial electrical resistance (TEER) and low FITC-dextran paracellular permeability when compared to the control group. This could be explained by the higher levels of tight junction proteins (ZO-1 and Occludin) expression along with reduced expression of the apoptosis-related proteins (Bax and Caspase-3) noticed in the GOP-treated cells, highlighting its role in preserving intestinal permeability, through prevention of their degradation while maintaining normal levels of expression. Further confirmatory in vivo data showed that GOP-treated mice exhibited high concentrations of lymphocytes (CD3+, CD4+, CD8+) in the intestine, to rescue the irradiation-induced damage and restore baseline intestinal integrity. Therefore, we propose that GOP can be used as an adjuvant therapy to attenuate irradiation-induced immune dysfunction and intestinal injury in cancer patients.

Effects of Psychological, Environmental and Physical Stressors on the Gut Microbiota

Stress, a ubiquitous part of daily human life, has varied biological effects which are increasingly recognized as including modulation of commensal microorganisms residing in the gastrointestinal tract, the gut microbiota. In turn, the gut microbiota influences the host stress response and associated sequelae, thereby implicating the gut microbiota as an important mediator of host health. This narrative review aims to summarize evidence concerning the impact of psychological, environmental, and physical stressors on gut microbiota composition and function. The stressors reviewed include psychological stress, circadian disruption, sleep deprivation, environmental extremes (high altitude, heat, and cold), environmental pathogens, toxicants, pollutants, and noise, physical activity, and diet (nutrient composition and food restriction). Stressors were selected for their direct relevance to military personnel, a population that is commonly exposed to these stressors, often at extremes, and in combination. However, the selected stressors are also common, alone or in combination, in some civilian populations. Evidence from preclinical studies collectively indicates that the reviewed stressors alter the composition, function and metabolic activity of the gut microbiota, but that effects vary across stressors, and can include effects that may be beneficial or detrimental to host health. Translation of these findings to humans is largely lacking at present. This gap precludes concluding with certainty that transient or cumulative exposures to psychological, environmental, and physical stressors have any consistent, meaningful impact on the human gut microbiota. However, provocative preclinical evidence highlights a need for translational research aiming to elucidate the impact of stressors on the human gut microbiota, and how the gut microbiota can be manipulated, for example by using nutrition, to mitigate adverse stress responses.

Exercise has the guts: How physical activity may positively modulate gut microbiota in chronic and immune-based diseases

Limited animal and human research findings suggests that exercise might have a beneficial role for health gut. Cardiorespiratory fitness correlates with health-associated gut parameters such as taxonomic diversity and richness. Physical exercise may augment intestinal microbial diversity through several mechanisms including promotion of an anti-inflammatory state. Disease-associated microbial functions were linked to distinct taxa in previous studies of familial type 1 diabetes mellitus (T1D). An integrated multi-approach in the study of T1D, including physical exercise, is advocated. The present review explores how exercise might modulate gut microbiota and microbiome characteristics in chronic and immune-based diseases, given the demonstrated relationship between gut function and human health.

Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis

Exercise plays an important role in the prevention and treatment of chronic liver disease and associated metabolic disorders. A single bout of exercise induces tissue blood flow redistribution, which decreases splanchnic circulation and leads to physiologic hypoxia in the gastrointestinal system and liver. The transcription factor, hypoxia inducible factor-1α (HIF-1α), and its regulator, prolylhydroxylase 2 (PHD2), play pivotal roles in the response to oxygen flux by regulating downstream gene expression levels in the liver. We hypothesized that exercise increases the HIF-1α levels in the liver, and that the hepatic PHD2/HIF-1α axis is involved in postexercise restoration of systemic energy homeostasis. Through constant O₂ consumption, CO₂ production, food and water intake, and physical activity detection with metabolic chambers, we observed that one 30-min session of swimming exercise enhances systemic energy metabolism in mice. By using the noninvasive bioluminescence imaging ROSA26 oxygen-dependent domain Luc mouse model, we reveal that exercise increases in vivo HIFα levels in the liver. Intraperitoneal injections of the PHD inhibitor, dimethyloxalylglycine, mimicked exercise-induced HIFα increase, whereas the HIF-1α inhibitor, PX-478, blocked this effect. We next constructed liver-specific knockout (LKO) mouse models with albumin- Cre-mediated, hepatocyte-specific Hif1a and Phd2 deletion. Compared with their controls, Hif1a-LKO and Phd2-LKO mice exhibited distinct patterns of hepatic metabolism-related gene expression profiles. Moreover, Hif1a-LKO mice failed to restore systemic energy homeostasis after exercise. In conclusion, the current study demonstrates that a single bout of exercise disrupts systemic energy homeostasis, increasing the HIF-1α levels in the liver. These findings also provide evidence that the hepatic PHD2/HIF-1α axis is involved in postexercise systemic metabolic homeostasis.-Luo, B., Xiang, D., Wu, D., Liu, C., Fang, Y., Chen, P., Hu, Y.-P. Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis.

Fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 reduces bacterial translocation in rats treated with carbon tetrachloride

Probiotics can prevent pathological bacterial translocation by modulating intestinal microbiota and improving the gut barrier. The aim was to evaluate the effect of a fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 on bacterial translocation in rats with carbon tetrachloride (CCl₄)-induced cirrhosis. Sprague-Dawley rats treated with CCl₄ were randomized into a probiotic group that received fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 in drinking water or a water group that received water only. Laparotomy was performed one week after ascites development. We evaluated bacterial translocation, intestinal microbiota, the intestinal barrier and cytokines in mesenteric lymph nodes and serum. Bacterial translocation decreased and gut dysbiosis improved in the probiotic group compared to the water group. The ileal β-defensin-1 concentration was higher and ileal malondialdehyde levels were lower in the probiotic group than in water group. There were no differences between groups in serum cytokines but TNF-α levels in mesenteric lymph nodes were lower in the probiotic group than in the water group. Fermented milk containing Lactobacillus paracasei subsp. paracasei CNCM I-1518 decreases bacterial translocation, gut dysbiosis and ileal oxidative damage and increases ileal β-defensin-1 expression in rats treated with CCl₄, suggesting an improvement in the intestinal barrier integrity.

Effects of a structured exercise programme in sedentary dogs with chronic diarrhoea

The aim of this investigation was to evaluate the effects of a structured exercise programme in sedentary dogs with chronic diarrhoea. Twenty-two dogs were enrolled in the study. All dogs received oral prednisolone (1 mg/kg/day for 14 days, followed by a tapering dosage) for 10 weeks. After four weeks of prednisolone treatment, dogs were assigned to either the exercise or control group (n=11 each). Owners of dogs in the exercise group were instructed to guide their dogs in structured exercise training (low-intensity to moderate-intensity aerobic and resistance exercise three to five days per week). After 10 weeks of prednisolone treatment with concomitant 6 weeks of complementary exercise, the Canine Inflammatory Bowel Disease Activity Index (CIBDAI) score had decreased significantly in the exercise group (from 8.8±1.5 at the start of the exercise programme to 2.4±1.5; P<0.001); no such change was observed in the control group (from 9.2±0.9 to 9.2±1.1). CIBDAI scores differed significantly between the groups at the end of the 10-week study period (P<0.001). The exercise programme affected all six CIBDAI parameters significantly; bodyweight (P<0.001, adjusted r²=0.722) was most affected. A structured exercise programme may have positive effects on clinical symptoms in sedentary dogs with chronic diarrhoea.

Suppression of TNF-α and free radicals reduces systematic inflammatory and metabolic disorders: Radioprotective effects of ginseng oligopeptides on intestinal barrier function and antioxidant defense

Irradiation therapy is markedly associated with intestinal injure and oxidant stress. This study aimed to investigate the effects of ginseng (Panax ginseng C.A. Mey.) oligopeptides (GOP) on irradiation-induced intestinal injury and antioxidant defense in mice. BALB/c mice (8 weeks old) were randomly divided into six groups: vehicle control, irradiation control (IR), IR+whey protein [0.30 g/kg body weight (BW)], IR+GOP 0.15 g/kg BW, IR+GOP 0.30 g/kg BW and IR+GOP 0.60 g/kg BW. Postirradiation 30-day survival trial, white blood cells count and bone marrow hematopoietic system damage were performed to identify the injury degree induced by irradiation. Then, histopathology analysis was observed and intestinal permeability in vivo was quantified with fluorescein isothiocyanate-dextran. The enzyme-linked immunosorbent assay was used to determine antioxidant ability, plasma inflammatory cytokines, diamine oxidase (DAO) and endotoxin (LPS) levels. The immunohistochemistry assay was used to analyze the expression levels of tight junction proteins. We found that GOP-treated mice exhibited lower concentrations of plasma LPS and DAO and decreased instructors of inflammatory and oxidative stress which were linked to the lower intestinal permeability and higher tight junction proteins expression. The blockage of GOP was linked with the reduction of TNF-α and free radicals. The 15-day pretreatment of GOP could exhibit radioprotective effects, and another 15-day posttreatment benefited the quick repair of irradiation-induced injury. We confirm that GOP would exhibit effective therapeutic value on attenuating irradiation-induced hematopoietic, gastrointestinal and oxidative injury in cancer patients.

Effects of voluntary exercise on apoptosis and cortisol after chronic restraint stress in mice

[Purpose]

To determine whether voluntary exercise (wheel running) has the potential of relieving stress.

[Methods]

In this study, restraint stress with or without voluntary wheel running was performed for mice housed in individual cages. A total of 21 ICR male mice were assigned into control (CON), restraint stress with voluntary exercise (RSVE), or restraint stress (RS) without voluntary exercise groups (n = 7 each).

[Results]

No significant difference in body weight increase was found among the three groups, although CON and RS groups had a tendency of having smaller body weight increase compared to the RSVE group. No significant difference in the expression level of liver heat shock protein 70, Bcl-2, or p53 was found among the three groups. However, caspase-3 protein level in RS group was significantly higher than that in the other two groups. Blood cortisol concentration in RS was higher (p < 0.05) than that in RSVE or CON group. It was the lowest (p < 0.05) in the RSVE group.

[Conclusion]

Our findings suggest that apoptosis caused by chronic restraint stress might be suppressed by voluntary exercise in mice.

Can exercise affect the course of inflammatory bowel disease? Experimental and clinical evidence

The inflammatory bowel disease (IBD) consisting of Crohn's disease (CD) and ulcerative colitis (UC) are defined as idiopathic, chronic and relapsing intestinal disorders occurring in genetically predisposed individuals exposed to environmental risk factors such as diet and microbiome changes. Since conventional drug therapy is expensive and not fully efficient, there is a need for alternative remedies that can improve the outcome in patients suffering from IBD. Whether exercise, which has been proposed as adjunct therapy in IBD, can be beneficial in patients with IBD remains an intriguing question. In this review, we provide an overview of the effects of exercise on human IBD and experimental colitis in animal models that mimic human disease, although the information on exercise in human IBD are sparse and poorly understood. Moderate exercise can exert a beneficial ameliorating effect on IBD and improve the healing of experimental animal colitis due to the activity of protective myokines such as irisin released from working skeletal muscles. CD patients with higher levels of exercise were significantly less likely to develop active disease at six months. Moreover, voluntary exercise has been shown to exert a positive effect on IBD patients' mood, weight maintenance and osteoporosis. On the other hand, depending on its intensity and duration, exercise can evoke transient mild systemic inflammation and enhances pro-inflammatory cytokine release, thereby exacerbating the gastrointestinal symptoms. We discuss recent advances in the mechanism of voluntary and strenuous exercise affecting the outcome of IBD in patients and experimental animal models.

Maintaining physical activity during refeeding improves body composition, intestinal hyperpermeability and behavior in anorectic mice

A role of gut-brain axis emerges in the pathophysiology of anorexia nervosa and maintaining adapted physical activity during refeeding remains discussed. We aimed to assess gastrointestinal protein metabolism and investigate the contribution of physical activity during refeeding in C57BL/6 mice with activity-based anorexia (ABA). ABA mice exhibited lower body weight and food intake with increase of lean mass/fat mass ratio and fat oxidation. Colonic permeability was increased in ABA. Ad libitum food access was then restored and ABA group was divided into two subgroups, with access to running wheel (ABA-PA) or not (ABA-NPA). After refeeding, fat free mass was completely restored only in ABA-PA. Colonic permeability was enhanced in ABA-NPA. Finally, muscle kynurenine conversion into kynurenic acid was lower in ABA-NPA who also exhibited altered behavior. Maintaining physical activity during refeeding may thus limit colonic hyperpermeability and improve behavior in anorectic mice.

Exercise and the microbiota

Sedentary lifestyle is linked with poor health, most commonly obesity and associated disorders, the corollary being that exercise offers a preventive strategy. However, the scope of exercise biology extends well beyond energy expenditure and has emerged as a great 'polypill', which is safe, reliable and cost-effective not only in disease prevention but also treatment. Biological mechanisms by which exercise influences homeostasis are becoming clearer and involve multi-organ systemic adaptations. Most of the elements of a modern lifestyle influence the indigenous microbiota but few studies have explored the effect of increased physical activity. While dietary responses to exercise obscure the influence of exercise alone on gut microbiota, professional athletes operating at the extremes of performance provide informative data. We assessed the relationship between extreme levels of exercise, associated dietary habits and gut microbiota composition, and discuss potential mechanisms by which exercise may exert a direct or indirect influence on gut microbiota.

[Correlation of the microbiota and intestinal mucosa in the pathophysiology and treatment of irritable bowel, irritable eye, and irritable mind syndrome]

Accumulating clinical evidence supports co-morbidity of irritable bowel, irritable eye and irritable mind symptoms. Furthermore, perturbation of the microbiota-host symbiosis (dysbiosis) is considered a common pathogenic mechanism connecting gastrointestinal, ocular and neuropsychiatric symptoms. Consequently, maintaining or restoring microbiota-host symbiosis represents a new approach to treat these symptoms or to prevent their relapses. Current treatment approach assigned a primary role to live probiotics alone or in combination with prebiotics to enhance colonization of beneficial bacteria and to strengthen the symbiosis. However, several papers showed major benefits of heat-killed probiotics as compared to their live counterparts on both intestinal and systemic symptoms. Recently, in addition to killing probiotics, in a proof of concept study lysates (fragments) of probiotics in combination with vitamins A, B, D and omega 3 fatty acids were successfully tested. These findings suggested a conceptual change in the approach addressed to both the microbiota and host as targets for intervention.

Special issue on exercise immunology: current perspectives on aging, health and extreme performance

The aim of this special issue is to highlight outstanding exemplars of empirical research and review papers that reflect the breadth of current developments in exercise immunology. The contributions to this issue are categorized according to four major themes: (1) exercise and immune-aging; (2) the effects of acute exercise on cellular shifts and gene expression; (3) the effects of exercise on immune regulation during stress and disease; and (4) extreme performance and the impact of dietary counter measures on immunity. We discuss the papers appearing in this issue, in accordance with these major themes, and summarize their important contributions to this exciting and expanding field.

The role of physical exercise in inflammatory bowel disease

We reviewed and analyzed the relationship between physical exercise and inflammatory bowel disease (IBD) which covers a group of chronic, relapsing, and remitting intestinal disorders including Crohn's disease (CD) and ulcerative colitis. The etiology of IBD likely involves a combination of genetic predisposition and environmental risk factors. Physical training has been suggested to be protective against the onset of IBD, but there are inconsistencies in the findings of the published literature. Hypertrophy of the mesenteric white adipose tissue (mWAT) is recognized as a characteristic feature of CD, but its importance for the perpetuation of onset of this intestinal disease is unknown. Adipocytes synthesize proinflammatory and anti-inflammatory cytokines. Hypertrophy of mWAT could play a role as a barrier to the inflammatory process, but recent data suggest that deregulation of adipokine secretion is involved in the pathogenesis of CD. Adipocytokines and macrophage mediators perpetuate the intestinal inflammatory process, leading to mucosal ulcerations along the mesenteric border, a typical feature of CD. Contracting skeletal muscles release biologically active myokines, known to exert the direct anti-inflammatory effects, and inhibit the release of proinflammatory mediators from visceral fat. Further research is required to confirm these observations and establish exercise regimes for IBD patients.