Gut microbiota and mTOR signaling: Insight on a new pathophysiological interaction

New insights into the immune regulation and tissue repair of Litopenaeus vannamei during temperature fluctuation using TMT-based proteomics

To investigate shrimp immunoregulation and tissue self-repair mechanism during temperature fluctuation stage, Litopenaeus vannamei (L. vannamei) was treated under conditions of gradual cooling from an acclimation temperature (28 °C, C group) to 13 °C (T group) in 2 days with a cooling rate of 7.5 °C/d and then rewarmed to 28 °C (R group) with the same rate. Tandem mass tags (TMT) -based proteomics technology was used to investigate the protein abundance changes of intestine in L. vannamei during temperature fluctuation. The results showed that a total of 5796 proteins with function annotation were identified. Of which, the abundances of 1978 proteins (34%) decreased after cooling and then increased after rewarming, 1498 proteins (26%) increased during the whole stage, 1263 proteins (22%) increased after cooling and then decreased after rewarming and 1057 proteins (18%) decreased during the whole stage. Differentially expressed proteins such as C-lectin, NFκBIA and Caspase may contributed to the regulation of immunity and tissue repair of shrimp intestine during the temperature fluctuation stage. These findings contribute to the better understanding of shrimp' regulatory mechanism against adverse environment.

Oral Treatment With Ileal Spores Triggers Immunometabolic Shifts in Chicken Gut

The animal gut is a major site affecting productivity via its role in mediating functions like food conversion and pathogen colonization. Live microorganisms like probiotics are widely used to improve poultry productivity. However, given that chicks receive their microbiota from the environment at-hatch, a bacterial treatment that can stimulate gut immune maturation in early life can benefit animal health. Thus, our lab has begun investigating alternative means to improve poultry health via single inoculation with microbial spores. In this study, we orally-inoculated day-old chicks with ileal scrapings (ISs) enriched for spores via chloroform treatment (SPORE) or non-treated (CON). At 3, 7, and 14 days post-inoculation (dpi), gut permeability was measured via FITC-dextran assay in serum. Additionally, small intestinal scrapings (SISs) were tested for in vitro Salmonella killing and total IgA. Lastly, distal ileum was either fixed or flash-frozen for microscopy or kinome peptide array, respectively. Using bacterial 16S rRNA gene sequencing, SPORE and CON inocula were highly-similar in bacterial composition. However, spores were detected in SPORE but not in CON inoculum. Segmented filamentous bacteria (SFB) filaments were observed in the distal ileum in SPORE birds as early as 3 dpi and all birds at 7 and 14 dpi. Additionally, SFB were detected via PCR in the ceca, colonizing all SPORE birds at 3 dpi. At 3 dpi, SPORE birds exhibited lower gut permeability vs. CON. In SPORE birds, SISs induced greater Salmonella growth in vitro at 3 dpi yet significantly-reduced Salmonella load at 7 and 14 dpi compared to CON in an IgA-independent manner. SPORE distal ileal tissue exhibited unique upregulation of several immunometabolic processes vs. CON birds, including innate (Toll-like receptor, JAK-STAT) and adaptive (T/B cell receptor, T_H17 differentiation) immune pathways, PI3K/Akt signaling, mTOR signaling, and insulin-related pathways. Collectively, these data suggest oral inoculation with ileal spores generally-improved gut health.

Importance: We report that ileal, spore-forming commensal microbes have potent effects on ileum immunometabolism. Additionally, we identify a functional ileal phenotype in spore-treated chickens, which matched several of the observed immunometabolic changes and was associated with SFB colonization in the ileum.

Autophagy and metabolism

Metabolism consists of diverse life-sustaining chemical reactions in living organisms. Autophagy is a highly conservative process that responds to various internal and external stresses. Both processes utilize surrounding resources to provide energy and nutrients for the cell. Autophagy progression may proceed to the degradative or secretory pathway determined by Rab family proteins. The former is a degradative and lysosome-dependent catabolic process that produces energy and provides nutrients for the synthesis of essential proteins. The degradative pathway also balances the energy source of the cell and regulates tissue homeostasis. The latter is a newly discovered pathway in which the autophagosome is fused with the plasma membrane. Secretory autophagy participates in diverse functions and diseases ranging from the spread of viral particles to cancer and neurodegenerative diseases. Aberrant metabolism in the body causes various metabolic syndromes. This review explores the relationships among autophagy, metabolism, and related diseases.

Gut-organ axis: a microbial outreach and networking

Human gut microbiota (GM) includes a complex and dynamic population of microorganisms that are crucial for well-being and survival of the organism. It has been reported as diverse and relatively stable with shared core microbiota, including Bacteroidetes and Firmicutes as the major dominants. They are the key regulators of body homeostasis, involving both intestinal and extra-intestinal effects by influencing many physiological functions such as metabolism, maintenance of barrier homeostasis, inflammation and hematopoiesis. Any alteration in GM community structures not only trigger gut disorders but also influence other organs and cause associated diseases. In recent past, the GM has been defined as a 'vital organ' with its involvement with other organs; thus, establishing a link or a bi- or multidirectional communication axis between the organs via neural, endocrine, immune, humoral and metabolic pathways. Alterations in GM have been linked to several diseases known to humans; although the exact interaction mechanism between the gut and the organs is yet to be defined. In this review, the bidirectional relationship between the gut and the vital human organs was envisaged and discussed under several headings. Furthermore, several disease symptoms were also revisited to redefine the communication network between the gut microbes and the associated organs.

Microbiota in cerebrovascular disease: A key player and future therapeutic target

Stroke is the second leading cause of death and a significant cause of disability worldwide. Recent advances in DNA sequencing, proteomics, metabolomics, and computational tools are dramatically increasing access to the identification of host-microbiota interactions in systemic diseases. In this review, we describe the accumulating evidence showing how human microbiota plays an essential role in cerebrovascular diseases. We introduce the symbiotic relationships between microbiota and the mucosal immune system, focusing on differences by anatomical sites. Microbiota directly or indirectly contributes to the pathogenesis of traditional vascular risk factors including age, obesity, diabetes mellitus, dyslipidemia, and hypertension. Moreover, recent studies proposed independent effects of the microbiome on the progression of various subtypes of stroke through direct microbial invasion, exotoxins, functional amyloids, inflammation, and microbe-derived metabolites. We propose the critical concept of gene-microbial interaction to elucidate the heterogeneity of stroke and provide possible therapeutic avenues. We suggest ways to resolve the vast inter-individual diversity of cerebrovascular disease and mechanisms for personalized prevention and treatment.

The relationship between acne vulgaris and irritable bowel syndrome: A preliminary study

BACKGROUND

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease characterized by chronic abdominal pain and changes in bowel movements without underlying organic pathology. Many skin diseases have been reported to be more common in individuals with functional bowel diseases.

AIMS

In this study, we aimed to investigate a possible relationship between acne vulgaris (AV) and IBS.

PATIENTS/METHODS

This prospective controlled study included patients with AV and healthy volunteers. All the subjects were evaluated in terms of the presence of IBS. The diagnosis of IBS was made based on the ROME IV diagnostic criteria. The clinical severity of AV was calculated using the global acne grading system (GAGS).

RESULTS

A total of 300 patients with acne vulgaris and 300 age and gender-matched healthy controls were included in the study. The majority of the patients were female (n = 175, 58.3%). The mean ages of the patients and controls were 20.22 ± 5.24 years and 20.49 ± 5.36 years, respectively. A total of 183 patients (61.0%) and 84 (28.0%) controls were diagnosed with IBS based on the Rome IV diagnostic criteria. The frequency of IBS was statistically significantly higher in the patient group than in the control group. (P = .001). There was also statistically significant relationship between the GAGS scores and IBS diagnosis (P = .001), abnormal stool form (P = .001), abdominal distention (P = .001), and feeling of incomplete evacuation (P = .001).

CONCLUSION

Our study showed that IBS is significantly more common in patients with AV than in healthy controls. Additionally, GAGS scores were higher in patients diagnosed with IBS. To the best of our knowledge, this is the first study focusing on the subject.

AMPK and the Need to Breathe and Feed: What's the Matter with Oxygen?

We live and to do so we must breathe and eat, so are we a combination of what we eat and breathe? Here, we will consider this question, and the role in this respect of the AMP-activated protein kinase (AMPK). Emerging evidence suggests that AMPK facilitates central and peripheral reflexes that coordinate breathing and oxygen supply, and contributes to the central regulation of feeding and food choice. We propose, therefore, that oxygen supply to the body is aligned with not only the quantity we eat, but also nutrient-based diet selection, and that the cell-specific expression pattern of AMPK subunit isoforms is critical to appropriate system alignment in this respect. Currently available information on how oxygen supply may be aligned with feeding and food choice, or vice versa, through our motivation to breathe and select particular nutrients is sparse, fragmented and lacks any integrated understanding. By addressing this, we aim to provide the foundations for a clinical perspective that reveals untapped potential, by highlighting how aberrant cell-specific changes in the expression of AMPK subunit isoforms could give rise, in part, to known associations between metabolic disease, such as obesity and type 2 diabetes, sleep-disordered breathing, pulmonary hypertension and acute respiratory distress syndrome.

IL-37 Ameliorating Allergic Inflammation in Atopic Dermatitis Through Regulating Microbiota and AMPK-mTOR Signaling Pathway-Modulated Autophagy Mechanism

Interaction between eosinophils and dermal fibroblasts is essential for provoking allergic inflammation in atopic dermatitis (AD). In vitro co-culture of human eosinophils and dermal fibroblasts upon AD-related IL-31 and IL-33 stimulation, and in vivo MC903-induced AD murine model were employed to investigate the anti-inflammatory mechanism of IL-1 family cytokine IL-37 in AD. Results showed that IL-37b could inhibit the in vitro induction of AD-related pro-inflammatory cytokines IL-6 and TNF-α, and chemokines CXCL8, CCL2 and CCL5, increase autophagosome biogenesis-related LC3B, and decrease autophagy-associated ubiquitinated protein p62 by regulating intracellular AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) signaling pathway. In CRISPR/Cas9 human IL-37b knock-in mice, IL-37b could significantly alleviate MC903-stimulated ear tissue swelling, itching sensation and the level of circulating cytokine IL-6 and ear in situ expression of AD-related TNF-α, CCL5 and transforming growth factor-β. Moreover, IL-37b could significantly upregulate Foxp3+ regulatory T cells (Treg) in spleen and ear together with significantly increased serum Treg cytokine IL-10, and decrease eosinophil infiltration in ear lesion. IL-37b knock-in mice showed a distinct intestinal microbiota metabolic pattern upon MC903 stimulation. Furthermore, IL-37b restored the disordered gut microbiota diversity, through regulating the in vivo autophagy mechanism mediated by intestinal metabolite 3-methyladenine, adenosine monophosphate, 2-hydroxyglutarate, purine and melatonin. In summary, IL-37b could significantly ameliorate eosinophils-mediated allergic inflammation via the regulation of autophagy mechanism, intestinal bacterial diversity and their metabolites in AD. Results therefore suggest that IL-37 is a potential anti-inflammatory cytokine for AD treatment.

Activation of mTOR Signaling Pathway in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and occurs mainly in patients with liver cirrhosis. The mammalian target of rapamycin (mTOR) signaling pathway is involved in many hallmarks of cancer including cell growth, metabolism re-programming, proliferation and inhibition of apoptosis. The mTOR pathway is upregulated in HCC tissue samples as compared with the surrounding liver cirrhotic tissue. In addition, the activation of mTOR is more intense in the tumor edge, thus reinforcing its role in HCC proliferation and spreading. The inhibition of the mTOR pathway by currently available pharmacological compounds (i.e., sirolimus or everolimus) is able to hamper tumor progression both in vitro and in animal models. The use of mTOR inhibitors alone or in combination with other therapies is a very attractive approach, which has been extensively investigated in humans. However, results are contradictory and there is no solid evidence suggesting a true benefit in clinical practice. As a result, neither sirolimus nor everolimus are currently approved to treat HCC or to prevent tumor recurrence after curative surgery. In the present comprehensive review, we analyzed the most recent scientific evidence while providing some insights to understand the gap between experimental and clinical studies.

Heat-shock transcription factor 2 promotes sodium butyrate-induced autophagy by inhibiting mTOR in ulcerative colitis

Butyrate-induced autophagy and anti-inflammatory effects of IECs plays an important role in UC. HSP has been proved to be associated with autophagy. HSF2, as an important regulator of HSP, has been determined to be highly expressed in UC. This study was designed to elucidate the relationship between HSF2, butyrate and epithelial autophagy and the potential mechanism of HSF2-related autophagy in UC. The autophagy levels and HSF2 expression in intestinal mucosa were increased in UC patients compared to controls. In DSS colitis models, hsf2^-/- mice exhibited more severe intestinal inflammation and lower autophagy levels than wild-type mice. HSF2 expression could be induced by sodium butyrate and LPS as a dose-response relationship in HT-29 cells, epigenetically via increasing histone acetylation levels at the promoter region by sodium butyrate. Autophagy induced by sodium butyrate was promoted by overexpression HSF2 in HT-29 cells. Moreover, overexpression HSF2 decreased the expression and phosphorylation levels of PI3K, Akt and mTOR induced by sodium butyrate. HSF2 might induced by sodium butyrate and inflammation and played protective roles in UC by enhancing autophagy of IECs. This indicated that HSF2 may be a critical target for autophagy modulation and a new potential therapeutic target in UC.

Role of the microbiome in occurrence, development and treatment of pancreatic cancer

Pancreatic cancer is one of the most lethal malignancies. Recent studies indicated that development of pancreatic cancer may be intimately connected with the microbiome. In this review, we discuss the mechanisms through which microbiomes affect the development of pancreatic cancer, including inflammation and immunomodulation. Potential therapeutic and diagnostic applications of microbiomes are also discussed. For example, microbiomes may serve as diagnostic markers for pancreatic cancer, and may also play an important role in determining the efficacies of treatments such as chemo- and immunotherapies. Future studies will provide additional insights into the various roles of microbiomes in pancreatic cancer.

Sepsis roadmap: What we know, what we learned, and where we are going

Sepsis is a life-threatening condition originating as a result of systemic blood infection causing, one or more organ damage due to the dysregulation of the immune response. In 2017, the world health organization (WHO) declared sepsis as a disease of global health priority, needing special attention due to its high prevalence and mortality around the world. Most of the therapeutics targeting sepsis have failed in the clinics. The present review highlights the history of the sepsis, its immunopathogenesis, and lessons learned after the failure of previously used immune-based therapies. The subsequent section, where to go describes in details the importance of the complement system (CS), autophagy, inflammasomes, and microbiota along with their targeting to manage sepsis. These systems are interconnected to each other, thus targeting one may affect the other. We are in an urgent need for a multi-targeting therapeutic approach for sepsis.

The Microbiome and Aging

Aging is a natural process of organismal decay that underpins the development of myriad diseases and disorders. Extensive efforts have been made to understand the biology of aging and its regulation, but most studies focus solely on the host organism. Considering the pivotal role of the microbiota in host health and metabolism, we propose viewing the host and its microbiota as a single biological entity whose aging phenotype is influenced by the complex interplay between host and bacterial genetics. In this review we present how the microbiota changes as the host ages, but also how the intricate relationship between host and indigenous bacteria impacts organismal aging and life span. In addition, we highlight other microbiota-dependent mechanisms that potentially regulate aging, and present experimental animal models for addressing these questions. Importantly, we propose microbiome dysbiosis as an additional hallmark and biomarker of aging.

A longitudinal, epigenome-wide study of DNA methylation in anorexia nervosa: results in actively ill, partially weight-restored, long-term remitted and non-eating-disordered women

Background

This study explored state-related tendencies in DNA methylation in people with anorexia nervosa.

Methods

We measured genome-wide DNA methylation in 75 women with active anorexia nervosa (active), 31 women showing stable remission of anorexia nervosa (remitted) and 41 women with no eating disorder (NED). We also obtained post-intervention methylation data from 52 of the women from the active group.

Results

Comparisons between members of the active and NED groups showed 58 differentially methylated sites (Q < 0.01) that corresponded to genes relevant to metabolic and nutritional status (lipid and glucose metabolism), psychiatric status (serotonin receptor activity) and immune function. Methylation levels in members of the remitted group differed from those in the active group on 265 probes that also involved sites associated with genes for serotonin and insulin activity, glucose metabolism and immunity. Intriguingly, the direction of methylation effects in remitted participants tended to be opposite to those seen in active participants. The chronicity of Illness correlated (usually inversely, at Q < 0.01) with methylation levels at 64 sites that mapped onto genes regulating glutamate and serotonin activity, insulin function and epigenetic age. In contrast, body mass index increases coincided (at Q < 0.05) with generally increased methylation-level changes at 73 probes associated with lipid and glucose metabolism, immune and inflammatory processes, and olfaction.

Limitations

Sample sizes were modest for this type of inquiry, and findings may have been subject to uncontrolled effects of medication and substance use.

Conclusion

Findings point to the possibility of reversible epigenetic alterations in anorexia nervosa, and suggest that an adequate pathophysiological model would likely need to include psychiatric, metabolic and immune components.

Protein Supplements and Their Relation with Nutrition, Microbiota Composition and Health: Is More Protein Always Better for Sportspeople?

Sports nutrition products are developed and targeted mainly for athletes to improve their nutrient intake, performance, and muscle growth. The fastest growing consumer groups for these products are recreational sportspeople and lifestyle users. Although athletes may have elevated physiological protein requirements and they may benefit from dietary supplements, the evidence regarding the role of dietary protein and supplements in the nutrition of recreational sportspeople and sedentary populations is somewhat complex and contradictory. In high-protein diets, more undigested protein-derived constituents end up in the large intestine compared to moderate or low-protein diets, and hence, more bacterial amino acid metabolism takes place in the colon, having both positive and negative systemic and metabolic effects on the host. The aim of the present review is to summarize the impact of the high-protein products and diets on nutrition and health, in sportspeople and in sedentary consumers. We are opening the debate about the current protein intake recommendations, with an emphasis on evidence-based effects on intestinal microbiota and personalized guidelines regarding protein and amino acid supplementation in sportspeople and lifestyle consumers.

AICAR prolongs corneal allograft survival via the AMPK-mTOR signaling pathway in mice

Immune rejection is a critical complication that results in the graft failure after corneal transplantation. Thus, there remains a need for new therapies for allograft rejection. AICAR (aminoimidazole-4-carboxamide ribonucleoside) is an, as adenosine monophosphate-activated protein kinase (AMPK) activator and a purine nucleoside with a wide range of metabolic effects, including activation of AMPK. More recently, it was reported that it is possible to inhibiting organs rejection and prolong the graft survival time in various models of organ transplantation. In this study, we systematically evaluated the efficacy of AICAR as a treatment modality for inhibiting allograft rejection in a mouse model of corneal transplantation. We found that AICAR significantly suppressed the opacity, edema, and vascularization of the graft, resulting in prolonged corneal allograft survival. AICAR treatment also significantly decreased central corneal thickness. Moreover, the AICAR-treated group showed decreased expression of IB4 and VEGF as compared to the control group. In addition, the mRNA expression of T helper 1 cytokines (IL-2, INF-γ, and TNF-α) was suppressed, and the expression of T helper 2 cytokines (IL-4, IL-5, and IL-13) was elevated by AICAR. Furthermore, the western blotting results revealed that AICAR stimulated AMPK activation and inhibited angiogenesis and inflammation possibly by subsequently suppressing mTOR phosphorylation. By contrast, the AMPK inhibitor Compound C (also called dorsomorphin) had the opposite effect. Our results showed that Compound C blocked AMPK-mTOR signaling and promoted the angiogenesis and inflammation, thus compromising the graft survival. These results suggest that AICAR may be a potential option for inhibiting the corneal graft rejection and for prolonging the graft survival.

Autophagy: roles in intestinal mucosal homeostasis and inflammation

The intestinal mucosa is a site of multiple stressors and forms the barrier between the internal and external environment. In the intestine, a complex interplay between the microbiota, epithelial barrier and the local immune system maintains homeostasis and promotes a healthy gut. One of the major cellular catabolic processes that regulate this homeostasis is autophagy. Autophagy is required to maintain anti-microbial defense, epithelial barrier integrity and mucosal immune response. Dysregulation of the autophagy process causes disruption of several aspects of the intestinal epithelium and the immune system that can lead to an inappropriate immune response and subsequent inflammation. Genome-wide association studies have found an association between several risk loci in autophagy genes and inflammatory bowel disease. The aim of the current review is to provide an update on the role of autophagy in intestinal mucosal physiology and in the control of inappropriate inflammation.

Abnormality in Maternal Dietary Calcium Intake During Pregnancy and Lactation Promotes Body Weight Gain by Affecting the Gut Microbiota in Mouse Offspring

SCOPE

To investigate the effects of calcium status in early life on adult body weight and the underlying mechanisms involved in gut microbiota and related lipid metabolism.

METHODS AND RESULTS

Three to four-week-old C57BL/6J female mice were fed diets with normal, insufficient, and excessive calcium respectively throughout pregnancy and lactation. The weaning male pups were fed with a high-fat diet for 16 weeks, with a normal-fat diet to the normal calcium group as control. The offspring fecal microbiota was analyzed by 16S rRNA high-throughput sequencing, and mRNA expressions of genes were determined by the real-time RT-PCR. Maternal insufficient or excessive calcium intake exacerbated offspring obesity, with expressional changes in the Fasn, Acc1, LPL, Fiaf, and PPAR-α genes in the liver or fat. The dysbiosis in gut microbiota in obese offspring was exacerbated by maternal imbalanced calcium intake, with increased Firmicutes and decreased Bacteroidetes in calcium insufficiency, and decreased Verrucomicrobia in calcium excess. Several genera, including Bacteroides, were reduced, and Lachnospiraceae and Lactobacillus were increased by maternal insufficient or excessive calcium intake.

CONCLUSION

Imbalance in maternal calcium intake promotes body weight gain in offspring, which may be mediated by calcium's modulation on the gut microbiota and lipid metabolism.

Western diet feeding influences gut microbiota profiles in apoE knockout mice

BACKGROUND

Gut microbiota plays an important role in many metabolic diseases such as diabetes and atherosclerosis. Apolipoprotein E (apoE) knock-out (KO) mice are frequently used for the study of hyperlipidemia and atherosclerosis. However, it is unknown whether apoE KO mice have altered gut microbiota when challenged with a Western diet.

METHODS

In the current study, we assessed the gut microbiota profiling of apoE KO mice and compared with wild-type mice fed either a normal chow or Western diet for 12 weeks using 16S pyrosequencing.

RESULTS

On a western diet, the gut microbiota diversity was significantly decreased in apoE KO mice compared with wild type (WT) mice. Firmicutes and Erysipelotrichaceae were significantly increased in WT mice but Erysipelotrichaceae was unchanged in apoE KO mice on a Western diet. The weighted UniFrac principal coordinate analysis exhibited clear separation between WT and apoE KO mice on the first vector (58.6%) with significant changes of two dominant phyla (Bacteroidetes and Firmicutes) and seven dominant families (Porphyromonadaceae, Lachnospiraceae, Ruminococcaceae, Desulfovibrionaceae, Helicobacteraceae, Erysipelotrichaceae and Veillonellaceae). Lachnospiraceae was significantly enriched in apoE KO mice on a Western diet. In addition, Lachnospiraceae and Ruminococcaceae were positively correlated with relative atherosclerosis lesion size in apoE KO.

CONCLUSIONS

Collectively, our study showed that there are marked changes in the gut microbiota of apoE KO mice, particularly challenged with a Western diet and these alterations may be possibly associated with atherosclerosis.

The Gut Microbiome as a Major Regulator of the Gut-Skin Axis

The adult intestine hosts a myriad of diverse bacterial species that reside mostly in the lower gut maintaining a symbiosis with the human habitat. In the current review, we describe the neoteric advancement in our comprehension of how the gut microbiota communicates with the skin as one of the main regulators in the gut-skin axis. We attempted to explore how this potential link affects skin differentiation and keratinization, its influence on modulating the cutaneous immune response in various diseases, and finally how to take advantage of this communication in the control of different skin conditions.