Sodium chloride exacerbates dextran sulfate sodium-induced colitis by tuning proinflammatory and antiinflammatory lamina propria mononuclear cells through p38/MAPK pathway in mice

Corin deficiency alleviates mucosal lesions in a mouse model of colitis induced by dextran sulfate sodium

AIMS

High dietary salt consumption is a risk factor for inflammatory bowel disease (IBD). Corin is a protease that activates atrial natriuretic peptide (ANP), thereby regulating sodium homeostasis. Corin acts in multiple tissues, including the intestine. In mice, corin deficiency impairs intestinal sodium excretion. This study aims to examine if reduced intestinal sodium excretion alters the pathophysiology of IBD.

MAIN METHODS

Wild-type (WT), Corin knockout (KO), and Corin kidney conditional KO (kcKO) mice were tested in a colitis model induced by dextran sulfide sodium (DSS). Effects of ANP on DSS-induced colitis were tested in WT and Corin KO mice. Body weight changes in the mice were monitored. Necropsy, histological analysis, and immunostaining studies were conducted to examine colon length and mucosal lesions. Fecal sodium levels were measured. RT-PCR was done to analyze proinflammatory genes in colon samples.

KEY FINDINGS

DSS-treated Corin KO mice had an ameliorated colitis phenotype with less body weight loss, longer colon lengths, smaller mucosal lesions, lower disease scores, more preserved goblet cells, and suppressed proinflammatory genes in the colon. In longitudinal studies, the DSS-treated Corin KO mice had delayed onset of colon mucosal lesions. ANP administration lessened the colitis in WT, but not Corin KO, mice. Analyses of WT, Corin KO, and Corin kcKO mice indicated that fecal sodium excretion, controlled by intestinal corin, may regulate inflammatory responses in DSS-induced colitis in mice.

SIGNIFICANCE

Our findings indicate a role of corin in intestinal pathophysiology, suggesting that reduced intestinal sodium level may offer protective benefits against IBD.

Role of Serum/Glucocorticoid-Regulated Kinase 1 (SGK1) in Immune and Inflammatory Diseases

Serum/glucocorticoid-regulated kinase 1 (SGK1), a member of the serine/threonine protein kinase gene family, is primarily regulated by serum and glucocorticoids. SGK1 is involved in the development of tumors and fibrotic diseases. However, relatively little research has been conducted on their role in immune and inflammatory diseases. SGK1 may act as a pivotal immune regulatory gene by modulating immune cells (e.g., T cells, macrophages, dendritic cells, and neutrophils) and functions and is involved in the pathogenesis of some immune and inflammatory diseases, such as inflammatory bowel disease, multiple sclerosis, allergic diseases, sepsis, and major depressive disorder. This review aims to provide an overview of the latest research focusing on the immune and inflammatory regulatory roles of SGK1 and provide new insights into diagnostic and therapeutic approaches for immune and inflammatory diseases.

Schisandrin protects against ulcerative colitis by inhibiting the SGK1/NLRP3 signaling pathway and reshaping gut microbiota in mice

BACKGROUND

According to the Chinese Pharmacopoeia, the fruit of Schisandra chinensis (Turcz.) Baill. (SC) is an important traditional Chinese medicine that can be used to treat diarrhea. Despite the increasing research on the anti-inflammatory and anti-oxidant aspects of SC, the studies on the anti-ulcerative colitis of Schisandrin (SCH), the main constituent of SC, are relatively few.

METHODS

The mice used in the study were randomly distributed into 6 groups: control, model, 5-ASA, and SCH (20, 40, 80 mg/kg/d). The mice in the model group were administered 3% (w/v) dextran sulfate sodium (DSS) through drinking water for 7 days, and the various parameters of disease activity index (DAI) such as body weight loss, stool consistency, and gross blood were measured. ELISA was used to detect inflammatory factors, and bioinformatics combined with transcriptome analysis was done to screen and verify relevant targets. 16S rDNA high-throughput sequencing was used to analyze the composition of the gut microbiota(GM), while mass spectrometry was done to analyze the changes in the content of bile acids (BAs) in the intestine.

RESULTS

Mice treated with SCH experienced significant weight gain, effectively alleviating the severity of colitis, and decreasing the levels of inflammatory factors such as TNF-α, IL-1β, IL-18, IL-6, and other related proteins (NLRP3, Caspase-1, SGK1) in UC mice. Furthermore, the analysis of GM and BAs in mice revealed that SCH increased the relative abundance of Lactobacilli spp, reduced the relative abundance of Bacteroides, and promoted the conversion of primary BAs to secondary BAs. These effects contributed to a significant improvement in the DSS-induced GM imbalance and the maintenance of intestinal homeostasis.

CONCLUSION

It seems that there is a close relationship between the SCH mechanism and the regulation of SGK1/NLRP3 pathway and the restoration of GM balance. Therefore, it can be concluded that SCH could be a potential drug for the treatment of UC.

Astragalus membranaceus as a Drug Candidate for Inflammatory Bowel Disease: The Preclinical Evidence

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that include Crohn's disease (CD) and ulcerative colitis (UC). Today, IBD has no successful treatment. As a result, it is of paramount importance to develop novel therapeutic agents for IBD prevention and treatment. Astragalus membranaceus (AMS) is a traditional Chinese medicine found in the AMS root. Modern pharmacological studies indicate that AMS and its constituents exhibit multiple bioactivities, such as anti-inflammatory, anti-oxidant, immune regulatory, anticancer, hypolipidemic, hypoglycemic, hepatoprotective, expectorant, and diuretic effects. AMS and its active constituents, which have been reported to be effective in IBD treatment, are believed to be viable candidate drugs for IBD treatment. These underlying mechanisms are associated with anti-inflammation, anti-oxidation, immunomodulation, intestinal epithelial repair, gut microbiota homeostasis, and improved energy metabolism. In this review, we summarize the efficacy and underlying mechanisms involved in IBD treatment with AMS and its active constituents in preclinical studies.

Cell-penetrating TLR inhibitor peptide alleviates ulcerative colitis by the functional modulation of macrophages

Toll-like receptors (TLRs) have a crucial role not only in triggering innate responses against microbes but in orchestrating an appropriate adaptive immunity. However, deregulated activation of TLR signaling leads to chronic inflammatory conditions such as inflammatory bowel disease (IBD). In this study, we evaluated the immunomodulatory potential of a TLR inhibitor in the form of a cell-penetrating peptide using an ulcerative colitis animal model. A peptide derived from the TIR domain of the TLR adaptor molecule TIRAP that was conjugated with a cell-penetrating sequence (cpTLR-i) suppressed the induction of pro-inflammatory cytokines such as TNF-α and IL-1β in macrophages. In DSS-induced colitis mice, cpTLR-i treatment ameliorated colitis symptoms, colonic tissue damage, and mucosal inflammation. Intriguingly, cpTLR-i attenuated the induction of TNF-α-expressing proinflammatory macrophages while promoting that of regulatory macrophages expressing arginase-1 and reduced type 17 helper T cell (Th17) responses in the inflamed colonic lamina propria. An in vitro study validated that cpTLR-i enhanced the differentiation of monocyte-driven macrophages into mature macrophages with a regulatory phenotype in a microbial TLR ligand-independent manner. Furthermore, the cocultivation of CD4 T cells with macrophages revealed that cpTLR-i suppressed the activation of Th17 cells through the functional modulation of macrophages. Taken together, our data show the immunomodulatory potential of the TLR inhibitor peptide and suggest cpTLR-i as a novel therapeutic candidate for the treatment of IBD.

Is Salt at Fault? Dietary Salt Consumption and Inflammatory Bowel Disease

Epidemiological trends have led to a growing consensus that diet plays a central role in the etiopathogenesis of inflammatory bowel diseases (IBD). A Western diet high in ultra-processed foods has been associated with an increased prevalence of IBD worldwide. Much attention has focused on components of the Western diet, including the high fat content, lack of fiber, added sugars, and use of additives, such as carrageenan and other emulsifiers. Less attention has been paid to the impact of high salt intake, an integral component of ultra-processed foods, which has increased dramatically in the US diet over the past 50 years. We review a growing body of literature linking the rise in dietary salt intake with the epidemiology of IBD, increased consumption of salt as a component of ultra-processed foods, high salt intake and imbalances in immune homeostasis, the effects of a high-salt diet on other inflammatory disorders, salt's impact on animal colitis models, salt as an underrecognized component in diet modification-induced remission of IBD, and directions for future investigation.

Neuroprotective Role of Lactoferrin during Early Brain Development and Injury through Lifespan

Early adverse fetal environments can significantly disturb central nervous system (CNS) development and subsequently alter brain maturation. Nutritional status is a major variable to be considered during development and increasing evidence links neonate and preterm infant impaired brain growth with neurological and psychiatric diseases in adulthood. Breastfeeding is one of the main components required for healthy newborn development due to the many "constitutive" elements breastmilk contains. Maternal intake of specific nutrients during lactation may alter milk composition, thus affecting newborn nutrition and, potentially, brain development. Lactoferrin (Lf) is a major protein present in colostrum and the main protein in human milk, which plays an important role in the benefits of breastfeeding during postnatal development. It has been demonstrated that Lf has antimicrobial, as well as anti-inflammatory properties, and is potentially able to reduce the incidence of sepsis and necrotizing enterocolitis (NEC), which are particularly frequent in premature births. The anti-inflammatory effects of Lf can reduce birth-related pathologies by decreasing the release of pro-inflammatory factors and inhibiting premature cervix maturation (also related to commensal microbiome abnormalities) that could contribute to disrupting brain development. Pre-clinical evidence shows that Lf protects the developing brain from neuronal injury, enhances brain connectivity and neurotrophin production, and decreases inflammation in models of perinatal inflammatory challenge, intrauterine growth restriction (IUGR) and neonatal hypoxia-ischemia (HI). In this context, Lf can provide nutritional support for brain development and cognition and prevent the origin of neuropsychiatric diseases later in life. In this narrative review, we consider the role of certain nutrients during neurodevelopment linking to the latest research on lactoferrin with respect to neonatology. We also discuss new evidence indicating that early neuroprotective pathways modulated by Lf could prevent neurodegeneration through anti-inflammatory and immunomodulatory processes.

The modulatory effect of high salt on immune cells and related diseases

BACKGROUND

The adverse effect of excessive salt intake has been recognized in decades. Researchers have mainly focused on the association between salt intake and hypertension. However, studies in recent years have proposed the existence of extra-renal sodium storage and provided insight into the immunomodulatory function of sodium.

OBJECTIVES

In this review, we discuss the modulatory effects of high salt on various innate and adaptive immune cells and immune-regulated diseases.

METHODS

We identified papers through electronic searches of PubMed database from inception to March 2022.

RESULTS

An increasing body of evidence has demonstrated that high salt can modulate the differentiation, activation and function of multiple immune cells. Furthermore, a high-salt diet can increase tissue sodium concentrations and influence the immune responses in microenvironments, thereby affecting the development of immune-regulated diseases, including hypertension, multiple sclerosis, cancer and infections. These findings provide a novel mechanism for the pathology of certain diseases and indicate that salt might serve as a target or potential therapeutic agent in different disease contexts.

CONCLUSION

High salt has a profound impact on the differentiation, activation and function of multiple immune cells. Additionally, an HSD can modulate the development of various immune-regulated diseases.

Mesenchymal stem cells against intestinal ischemia-reperfusion injury: a systematic review and meta-analysis of preclinical studies

Background

Intestinal ischemia–reperfusion injury (IRI) causes localized and distant tissue lesions. Multiple organ failure is a common complication of severe intestinal IRI, leading to its high rates of morbidity and mortality. Thus far, this is poorly treated, and there is an urgent need for new more efficacious treatments. This study evaluated the beneficial effects of mesenchymal stem cells (MSCs) therapy on intestinal IRI using many animal experiments.

Methods

We conducted a comprehensive literature search from 4 databases: Pubmed, Embase, Cochrane library, and Web of science. Primary outcomes included the survival rate, Chiu’s score, intestinal levels of IL-6, TNF-α and MDA, as well as serum levels of DAO, D-Lactate, and TNF-α. Statistical analysis was carried out using Review Manager 5.3.

Results

It included Eighteen eligible researches in the final analysis. We demonstrated that survival rates in animals following intestinal IRI were higher with MSCs treatment compared to vehicle treatment. Besides, MSCs treatment attenuated intestinal injury caused by IRI, characterized by lower Chiu’s score (− 1.96, 95% CI − 2.72 to − 1.19, P < 0.00001), less intestinal inflammation (IL-6 (− 2.73, 95% CI − 4.19 to − 1.27, P = 0.0002), TNF-α (− 3.00, 95% CI − 4.74 to − 1.26, P = 0.0007)) and oxidative stress (MDA (− 2.18, 95% CI − 3.17 to − 1.19, P < 0.0001)), and decreased serum levels of DAO (− 1.39, 95% CI − 2.07 to − 0.72, P < 0.0001), D-Lactate (− 1.54, 95% CI − 2.18 to − 0.90, P < 0.00001) and TNF-α (− 2.42, 95% CI − 3.45 to − 1.40, P < 0.00001). The possible mechanism for MSCs to treat intestinal IRI might be through reducing inflammation, alleviating oxidative stress, as well as inhibiting the apoptosis and pyroptosis of the intestinal epithelial cells.

Conclusions

Taken together, these studies revealed that MSCs as a promising new treatment for intestinal IRI, and the mechanism of which may be associated with inflammation, oxidative stress, apoptosis, and pyroptosis. However, further studies will be required to confirm these findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02896-y.

Jianpi Qinghua Fomula alleviates insulin resistance via restraining of MAPK pathway to suppress inflammation of the small intestine in DIO mice

Background

Jianpi Qinghua Fomula (JPQHF), a clinically proven prescription,has been applied to cure insulin resistance(IR) and type 2 diabetes (T2DM) for more than 20 years. Here, we will unravel the underlying molecular mechanisms relevant to the therapeutic actions of JPQHF.

Methods

High-fat(HF)diet-induced obesity(DIO)mouse were established in our research, along with insulin resistance. After the administration of JPQHF 5 or 6 weeks, the parameters of the glucose and lipid metabolism were measured. Flow cytometry and Luminex were utilized to assess the inflammation in small intestine,whilst Western blot was used to determine the relative expression levels of the MAPK pathway-related proteins. The glucose and lipid transporter of small intestine was assessed by immunofluorescence and ELISA, and the expression of insulin signaling pathway was detected by Western blot.

Results

The metabolic phenotypes of DIO mouse were ameliorated after 6-week oral administration of JPQHF; Meanwhile,JPQHF downregulated levels of IL-1β,IL-6, TNF-α and IFN-γ but upregulated the ratio of M2/M1 macrophages in the small intestine. The elevated expressions of p-P38 MAPK/P38 MAPK、p-JNK/JNK and p-ERK1/2/ERK1/2 were reversed by JPQHF. Moreover, JPQHF enhanced expression of PI3K,p-AKT/AKT, p-IRS1/ IRS1, p-IRS2/ IRS2 and apoB48 in small intestine, and facilitated the translocation of GLUT2 to the basal side of small intestine epithelial cells.

Conclusion

JPQHF alleviates insulin resistance in DIO mice, and this effect may be associated with its restraining of inflammation of small intestine via attenuating MAPK pathway, and then diminishes small intestinal glucose and lipid absorption.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03595-0.

Inhibitor of Differentiation-2 Protein Ameliorates DSS-Induced Ulcerative Colitis by Inhibiting NF-κB Activation in Neutrophils

The loss of inhibitor of differentiation-2 (ID2) could lead to the development of colitis in mice, supplementation with exogenous ID2 protein might be a potential strategy to ameliorate colitis. In this study, the effects of ID2 protein supplementation on Dextran sodium sulfate (DSS)-induced colitis were investigated. Firstly, we confirmed that the expression of ID2 was reduced in the colon tissues of DSS-induced colitis mice and patients with ulcerative colitis (UC). Then, we constructed a recombinant plasmid containing the human Id2 gene and expressed it in Escherichia coli (E. coli) successfully. After purification and identification, purified hID2 could ameliorate DSS-induced colitis efficiently in mice by improving disease symptoms, decreasing the levels of proinflammatory cytokines in colon tissues, maintaining the integrity of intestinal barrier and reducing the infiltration of neutrophils and macrophages in the colon. Further study showed that hID2 could be endocytosed efficiently by neutrophils and macrophages, and hID2 lost its protection function against colitis when neutrophils were depleted with an anti-Gr-1 antibody. hID2 decreased the mRNA levels of IL-6, IL-1β and TNF-α in lipopolysaccharides (LPS)-stimulated neutrophils and efficiently inhibited the activation of NF-κB signalling pathway in neutrophils. Interestingly, hID2 showed a synergistic role in inhibition of NF-κB activation with pyrrolidine dithiocarbamic acid (PDTC), an inhibitor of NF-κB activation. Therefore, this study demonstrated the potential use of hID2 to treat UC, and hID2 protein might be a promising anti-inflammatory agent that targets the NF-κB signalling pathway in neutrophils.

Common contributing factors to COVID-19 and inflammatory bowel disease

The devastating complications of coronavirus disease 2019 (COVID-19) result from an individual's dysfunctional immune response following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events ultimately leading to COVID-19. We have previously identified many contributing factors (CFs) (representing toxic exposure, lifestyle factors and psychosocial stressors) common to myriad chronic diseases. We hypothesized significant overlap between CFs associated with COVID-19 and inflammatory bowel disease (IBD), because of the strong role immune dysfunction plays in each disease. A streamlined dot-product approach was used to identify potential CFs to COVID-19 and IBD. Of the fifty CFs to COVID-19 that were validated for demonstration purposes, approximately half had direct impact on COVID-19 (the CF and COVID-19 were mentioned in the same record; i.e., CF---→COVID-19), and the other half had indirect impact. The nascent character of the COVID-19 core literature (∼ one year old) did not allow sufficient time for the direct impacts of many CFs on COVID-19 to be identified. Therefore, an immune system dysfunction (ID) literature directly related to the COVID-19 core literature was used to augment the COVID-19 core literature and provide the remaining CFs that impacted COVID-19 indirectly (i.e., CF---→immune system dysfunction---→COVID-19). Approximately 13000 potential CFs for myriad diseases (obtained from government and university toxic substance lists) served as the starting point for the dot-product identification process. These phrases were intersected (dot-product) with phrases extracted from a PubMed-derived IBD core literature, a nascent COVID-19 core literature, and the COVID-19-related immune system dysfunction (ID) core literature to identify common ID/COVID-19 and IBD CFs. Approximately 3000 potential CFs common to both ID and IBD, almost 2300 potential CFs common to ID and COVID-19, and over 1900 potential CFs common to IBD and COVID-19 were identified. As proof of concept, we validated fifty of these ∼3000 overlapping ID/IBD candidate CFs with biologic plausibility. We further validated 24 of the fifty as common CFs in the IBD and nascent COVID-19 core literatures. This significant finding demonstrated that the CFs indirectly related to COVID-19 -- identified with use of the immune system dysfunction literature -- are strong candidates to emerge eventually as CFs directly related to COVID-19. As discussed in the main text, many more CFs common to all these core literatures could be identified and validated. ID and IBD share many common risk/contributing factors, including behaviors and toxic exposures that impair immune function. A key component to immune system health is removal of those factors that contribute to immune system dysfunction in the first place. This requires a paradigm shift from traditional Western medicine, which often focuses on treatment, rather than prevention.

Clophosome alleviate dextran sulphate sodium-induced colitis by regulating gut immune responses and maintaining intestinal integrity in mice

Inflammatory bowel disease (IBD) is a chronic progressive disorder characterized by complicated gastrointestinal inflammation. Research on therapeutic agents is still urgent due to the lack of satisfactory treatments. Gut macrophages are considered to be predominant in excessive inflammatory responses. Thus, we aimed to investigate whether depletion of macrophages would have a beneficial effect on IBD and could be a potential therapeutic strategy. In this study, we established a 12-day Dextran sodium sulphate (DSS)-induced colitis mouse model and determined the effect of the macrophage depletion agent Clophosome (neutral clodronate liposomes; CNC). The results showed that CNC significantly alleviated the symptoms of colitis, as demonstrated by greater weight gain, decreased disease activity index (DAI) scores, and lower histopathological damage scores, as well was reduced levels of the proinflammatory cytokines interleukin (IL)-6 and tumour necrosis factor (TNF)-α. To investigate T cell subsets, cells were isolated from the lamina propria and cultured to analyse the expression of IL-17A, interferon (IFN)-γ and Foxp3 in CD4+ cells by flow cytometry. The data showed that during the process of colitis, the frequencies of CD4+ IL-17A+ T cells were significantly increased. Notably, CNC treatment markedly reduced the population of CD4+ IL-17A+ T cells, especially CD4+ IL-17A+ IFN-γ+ T cells. Furthermore, intestinal barrier integrity, as assessed by immunostaining of mucin and tight junction proteins, was severely disrupted in colitis. CNC improved the intestinal barrier by enhancing the expression of muc-2 and occludin. In summary, our findings demonstrated that CNC successfully ameliorated DSS-induced colitis and that its effect may be associated with inhibiting inflammatory responses and maintaining intestinal integrity.

Metabolic Shifts as the Hallmark of Most Common Diseases: The Quest for the Underlying Unity

A hyper-specialization characterizes modern medicine with the consequence of classifying the various diseases of the body into unrelated categories. Such a broad diversification of medicine goes in the opposite direction of physics, which eagerly looks for unification. We argue that unification should also apply to medicine. In accordance with the second principle of thermodynamics, the cell must release its entropy either in the form of heat (catabolism) or biomass (anabolism). There is a decreased flow of entropy outside the body due to an age-related reduction in mitochondrial entropy yield resulting in increased release of entropy in the form of biomass. This shift toward anabolism has been known in oncology as Warburg-effect. The shift toward anabolism has been reported in most diseases. This quest for a single framework is reinforced by the fact that inflammation (also called the immune response) is involved in nearly every disease. This strongly suggests that despite their apparent disparity, there is an underlying unity in the diseases. This also offers guidelines for the repurposing of old drugs.

Research Advances in Protective Effects of Ursolic Acid and Oleanolic Acid Against Gastrointestinal Diseases

The intestinal tract plays an essential role in protecting tissues from the invasion of external harmful substances due to impaired barrier function. Furthermore, it participates in immunomodulation by intestinal microorganisms, which is important in health. When the intestinal tract is destroyed, it can lose its protective function, resulting in multiple systemic complications. In severe cases, it may lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Thus far, there are no curative therapies for intestinal mucosal barrier injury, other than a few drugs that can relieve symptoms. Thus, the development of novel curative agents for gastrointestinal diseases remains a challenge. Ursolic acid (UA) and its isomer, Oleanolic acid (OA), are pentacyclic triterpene acid compounds. Both their aglycone and glycoside forms have anti-oxidative, anti-inflammatory, anti-ulcer, antibacterial, antiviral, antihypertensive, anti-obesity, anticancer, antidiabetic, cardio protective, hepatoprotective, and anti-neurodegenerative properties in living organisms. In recent years, several studies have shown that UA and OA can reduce the risk of intestinal pathological injury, alleviate intestinal dysfunction, and restore intestinal barrier function. The present study evaluated the beneficial effects of UA and OA on intestinal damage and diseases, including inflammatory bowel disease (IBD) and colorectal cancer (CRC).

From Maternal Diet to Neurodevelopmental Disorders: A Story of Neuroinflammation

Providing the appropriate quantity and quality of food needed for both the mother's well-being and the healthy development of the offspring is crucial during pregnancy. However, the macro- and micronutrient intake also impacts the body's regulatory supersystems of the mother, such as the immune, endocrine, and nervous systems, which ultimately influence the overall development of the offspring. Of particular importance is the association between unhealthy maternal diet and neurodevelopmental disorders in the offspring. Epidemiological studies have linked neurodevelopmental disorders like autism spectrum disorders, attention-deficit-hyperactivity disorder, and schizophrenia, to maternal immune activation (MIA) during gestation. While the deleterious consequences of diet-induced MIA on offspring neurodevelopment are increasingly revealed, neuroinflammation is emerging as a key underlying mechanism. In this review, we compile the evidence available on how the mother and offspring are both impacted by maternal dietary imbalance. We specifically explore the various inflammatory and anti-inflammatory effects of dietary components and discuss how changes in inflammatory status can prime the offspring brain development toward neurodevelopmental disorders. Lastly, we discuss research evidence on the mechanisms that sustain the relationship between maternal dietary imbalance and offspring brain development, involving altered neuroinflammatory status in the offspring, as well as genetic to cellular programming notably of microglia, and the evidence that the gut microbiome may act as a key mediator.

Metabolic and immunologic control of intestinal cell function by mTOR

The intestinal epithelium is one of the most quickly dividing tissues in our body, combining the absorptive advantages of a single layer with the protection of a constantly renewing barrier. It is continuously exposed to nutrients and commensal bacteria as well as microbial and host-derived metabolites, but also to hazards such as pathogenic bacteria and toxins. These environmental cues are sensed by the mucosa and a vast repertory of immune cells, especially macrophages. A disruption of intestinal homeostasis in terms of barrier interruption can lead to inflammatory bowel diseases and colorectal cancer, and macrophages have an important role in restoring epithelial function following injury. The mammalian/mechanistic target of rapamycin (mTOR) signalling pathway senses environmental cues and integrates metabolic responses. It has emerged as an important regulator of intestinal functions in homeostasis and disease. In this review, we are going to discuss intestinal mTOR signalling and metabolic regulation in different intestinal cell populations with a special focus on immune cells and their actions on intestinal function.

Inactivation of paracellular cation-selective claudin-2 channels attenuates immune-mediated experimental colitis in mice

The tight junction protein claudin-2 is upregulated in disease. Although many studies have linked intestinal barrier loss to local and systemic disease, these have relied on macromolecular probes. In vitro analyses show, however, that these probes cannot be accommodated by size- and charge-selective claudin-2 channels. We sought to define the impact of claudin-2 channels on disease. Transgenic claudin-2 overexpression or IL-13-induced claudin-2 upregulation increased intestinal small cation permeability in vivo. IL-13 did not, however, affect permeability in claudin-2-knockout mice. Claudin-2 is therefore necessary and sufficient to effect size- and charge-selective permeability increases in vivo. In chronic disease, T cell transfer colitis severity was augmented or diminished in claudin-2-transgenic or -knockout mice, respectively. We translated the in vitro observation that casein kinase-2 (CK2) inhibition blocks claudin-2 channel function to prevent acute, IL-13-induced, claudin-2-mediated permeability increases in vivo. In chronic immune-mediated colitis, CK2 inhibition attenuated progression in claudin-2-sufficient, but not claudin-2-knockout, mice, i.e., the effect was claudin-2 dependent. Paracellular flux mediated by claudin-2 channels can therefore promote immune-mediated colitis progression. Although the mechanisms by which claudin-2 channels intensify disease remain to be defined, these data suggest that claudin-2 may be an accessible target in immune-mediated disorders, including inflammatory bowel disease.

Chronic colitis induces meninges traffic of gut-derived T cells, unbalances M1 and M2 microglia/macrophage and increases ischemic brain injury in mice

Ischemic stroke is one of the most common diseases leading to death and is the primary cause of physical handicap. Recent studies have reported that chronic colitis increases the risk of ischemic stroke, but it is unknown whether chronic colitis participates in ischemic brain injury directly. A combined mouse model of chronic colitis induced by dextran sodium sulfate (DSS) and ischemic stroke induced by photochemical infarction was used in this study. We demonstrated that chronic colitis significantly increased the infarction volume, activated microglia/macrophage numbers, proliferation of M1 microglia/macrophage, non-gut-derived CD4+ T lymphocyte penetration and decreased neuron numbers in the peri-infarction at 7 d after stroke. Furthermore, gut-derived CD4+ T cell accumulation on the meninges was observed at 7 d after stroke. In addition, selective depletion of meningeal macrophages resulted in a reduction of infarction volume and the non-gut-derived CD4+ T lymphocyte penetration. We concluded that chronic colitis exacerbated ischemic stroke by promoting CD4+ T cell migration from the gut to the meninges and disequilibrium of M1 and M2 microglia/macrophages. We speculated that the gut-derived CD4+ T cells may interact with meningeal macrophages and result in non-gut-derived CD4+ T lymphocyte infiltration that aggravated brain injury in ischemic stroke.

Dietary Supplementation of Selenoneine-Containing Tuna Dark Muscle Extract Effectively Reduces Pathology of Experimental Colorectal Cancers in Mice

Selenoneine is an ergothioneine analog with greater antioxidant activity and is the major form of organic selenium in the blood, muscles, and other tissues of tuna. The aim of this study was to determine whether a selenoneine-rich diet exerts antioxidant activities that can prevent carcinogenesis in two types of colorectal cancer model in mice. We administrated selenoneine-containing tuna dark muscle extract (STDME) to mice for one week and used azoxymethane (AOM) and dextran sodium sulfate (DSS) for inducing colorectal carcinogenesis. Next, we examined the incidence of macroscopic polyps and performed functional analysis of immune cells from the spleen. In the AOM/DSS-induced colitis-associated cancer (CAC) model, the oral administration of STDME significantly decreased tumor incidence and inhibited the accumulation of myeloid-derived suppressor cells (MDSCs) while also inhibiting the downregulation of interferon-γ (IFN-γ) production during carcinogenesis. These results suggest that dietary STDME may be an effective agent for reducing colorectal tumor progression.