SIRT2 Contributes to the Regulation of Intestinal Cell Proliferation and Differentiation

In situ profiling reveals spatially metabolic injury in the initiation of polystyrene nanoplastic-derived intestinal epithelial injury in mice

Despite increasing concerns regarding the harmful effects of plastic-induced gut injury, mechanisms underlying the initiation of plastic-derived intestinal toxicity remain unelucidated. Here, mice were subjected to long-term exposure to polystyrene nanoplastics (PS-NPs) of varying sizes (80, 200, and 1000 nm) at doses relevant to human dietary exposure. PS-NPs exposure did not induce a significant inflammatory response, histopathological damage, or intestinal epithelial dysfunction in mice at a dosage of 0.5 mg/kg/day for 28 days. However, PS-NPs were detected in the mouse intestine, coupled with observed microstructural changes in enterocytes, including mild villous lodging, mitochondrial membrane rupture, and endoplasmic reticulum (ER) dysfunction, suggesting that intestinal-accumulating PS-NPs resulted in the onset of intestinal epithelial injury in mice. Mechanistically, intragastric PS-NPs induced gut microbiota dysbiosis and specific bacteria alterations, accompanied by abnormal metabolic fingerprinting in the plasma. Furthermore, integrated data from mass spectrometry imaging-based spatial metabolomics and metallomics revealed that PS-NPs exposure led to gut dysbiosis-associated host metabolic reprogramming and initiated intestinal injury. These findings provide novel insights into the critical gut microbial-host metabolic remodeling events vital to nanoplastic-derived-initiated intestinal injury.

Gut permeability among Astronauts during Space missions

The space environment poses substantial challenges to human physiology, including potential disruptions in gastrointestinal health. Gut permeability has only recently become widely acknowledged for its potential to cause adverse effects on a systemic level, rendering it a critical factor to investigate in the context of spaceflight. Here, we propose that astronauts experience the onset of leaky gut during space missions supported by transcriptomic and metagenomic analysis of human and murine samples. A genetic map contributing to intestinal permeability was constructed from a systematic review of current literature. This was referenced against our re-analysis of three independent transcriptomic datasets which revealed significant changes in gene expression patterns associated with the gut barrier. Specifically, in astronauts during flight, we observed a substantial reduction in the expression genes that are crucial for intestinal barrier function, goblet cell development, gut microbiota modulation, and immune responses. Among rodent spaceflight studies, differential expression of cytokines, chemokines, and genes which regulate mucin production and post-translational modifications suggest a similar dysfunction of intestinal permeability. Metagenomic analysis of feces from two murine studies revealed a notable reduction probiotic, short chain fatty acid-producing bacteria and an increase in the Gram-negative pathogens, including Citrobacter rodentium, Enterobacter cloacea, Klebsiella aerogenes, and Proteus hauseri which promote LPS circulation, a recipe for barrier disruption and systemic inflammatory activation. These findings emphasize the critical need to understand the underlying mechanisms and develop interventions to maintain gastrointestinal health in space.

Cistanche phenylethanoid glycosides induce apoptosis and pyroptosis in T-cell lymphoma

Cistanche deserticola, known for its extensive history in Traditional Chinese Medicine (TCM), is valued for its therapeutic properties. Recent studies have identified its anticancer capabilities, yet the mechanisms underlying these properties remain to be fully elucidated. In this study, we determined that a mixture of four cistanche-derived phenylethanoid glycosides (CPhGs), echinacoside, acteoside, 2-acetylacteoside, and cistanoside A, which are among the main bioactive compounds in C. deserticola, eliminated T-cell lymphoma (TCL) cells by inducing apoptosis and pyroptosis in vitro and attenuated tumor growth in vivo in a xenograft mouse model. At the molecular level, these CPhGs elevated P53 by inhibiting the SIRT2-MDM2/P300 and PI3K/AKT carcinogenic axes and activating PTEN-Bax tumor-suppressing signaling. Moreover, CPhGs activated noncanonical and alternative pathways to trigger pyroptosis. Interestingly, CPhGs did not activate canonical NLRP3-caspase-1 pyroptotic signaling pathway; instead, CPhGs suppressed the inflammasome factor NLRP3 and the maturation of IL-1β. Treatment with a caspase-1/4 inhibitor and silencing of Gasdermin D (GSDMD) or Gasdermin E (GSDME) partially rescued CPhG-induced cell death. Conversely, forced expression of NLRP3 restored cell proliferation. In summary, our results indicate that CPhGs modulate multiple signaling pathways to achieve their anticancer properties and perform dual roles in pyroptosis and NLRP3-driven proliferation. This study offers experimental support for the potential application of CPhGs in the treatment of TCL.

The epithelium takes the stage in asthma and inflammatory bowel diseases

The epithelium is a dynamic barrier and the damage to this epithelial layer governs a variety of complex mechanisms involving not only epithelial cells but all resident tissue constituents, including immune and stroma cells. Traditionally, diseases characterized by a damaged epithelium have been considered "immunological diseases," and research efforts aimed at preventing and treating these diseases have primarily focused on immuno-centric therapeutic strategies, that often fail to halt or reverse the natural progression of the disease. In this review, we intend to focus on specific mechanisms driven by the epithelium that ensure barrier function. We will bring asthma and Inflammatory Bowel Diseases into the spotlight, as we believe that these two diseases serve as pertinent examples of epithelium derived pathologies. Finally, we will argue how targeting the epithelium is emerging as a novel therapeutic strategy that holds promise for addressing these chronic diseases.

Enhancing surgical precision: unveiling the impact of preoperative colonoscopy in anal fistula patients

BACKGROUND

Anal fistula is a common benign anorectal disease that often requires surgical intervention for effective treatment. In recent years, preoperative colonoscopy as a diagnostic tool in patients with anal fistula has garnered increasing attention due to its potential clinical application value. By investigating underlying inflammatory bowel disease (IBD), polyps, and other abnormalities, preoperative colonoscopy can offer insights to refine surgical strategies and improve patient outcomes.

METHODS

This retrospective study focused on 1796 patients with various benign anorectal diseases who underwent preoperative intestinal endoscopy and met surgical criteria within the preceding three years at the First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine. Among these patients, 949 diagnosed with anal fistula comprised group A, while 847 patients without anal fistula were assigned to group B for comparison. The investigation encompassed an analysis of general patient information, endoscopic findings, polyp histopathology, distribution of bowel inflammation sites, and results of inflammatory bowel disease assessments between the two patient cohorts. A subgroup analysis was also conducted on 2275 anal fistula patients with no surgical contraindications. This subgroup was categorized into Group A (949 patients who underwent preoperative intestinal endoscopy) and Group C (1326 patients who did not undergo preoperative colonoscopy). The study compared the rates of detecting endoscopic lesions and IBD-related findings between the two subgroups.

RESULTS

The study initially confirmed the comparability of general patient information between groups A and B. Notably, the abnormal detection rate in group A was significantly higher than in group B (P < 0.01). In terms of endoscopic findings, the anal fistula group (group A) exhibited higher rates of detecting bowel inflammation, inflammatory bowel disease, and polyps compared to the non-anal fistula group (group B) (P < 0.05). The distribution of inflammation locations indicated higher detection rates in the terminal ileum, ileocecal region, and ascending colon for group A compared to group B (P < 0.05). Although the incidence of IBD in group A was higher than in group B, this difference did not reach statistical significance (P > 0.05). Subsequently, the analysis of the subgroup (groups A and C) revealed a significant disparity in intestinal endoscopic detection rates (P < 0.01) and statistically significant differences in detecting IBD (P < 0.05) and Crohn's disease (P < 0.05) between the two anal fistula subgroups.

CONCLUSIONS

The findings of this study underscore the substantial clinical value of preoperative colonoscopy in the comprehensive evaluation of patients with anal fistula. Preoperative colonoscopy aids in ruling out localized perianal lesions caused by underlying inflammatory bowel disease, thereby mitigating the likelihood of missed diagnoses and enhancing treatment outcomes. This research highlights the importance of incorporating preoperative colonoscopy as a valuable diagnostic tool in managing anal fistula patients.

LMP2 and TAP2 impair tumor growth and metastasis by inhibiting Wnt/β-catenin signaling pathway and EMT in cervical cancer

BACKGROUND

The roles of low molecular mass polypeptide 2 (LMP2) and transporter-associated with antigen processing (TAP2) in tumorigenesis are controversial. Here we aimed to explore the effect of LMP2 and TAP2 on the oncogenesis and metastasis of cervical cancer cells.

METHODS

The expressions of LMP2 and TAP2 in cervical cancer and normal tissues were determined by qPCR. Plate colony formation, cell counting kit-8 analysis and in vivo tumor xenograft assays were used to detect the tumor growth. Wound healing and transwell assays were used to detect the metastasis of cervical cancer. Gelatin zymography and western blotting assays were used to detect the effect of LMP2 and TAP2 on the EMT and Wnt/β-catenin pathway in cervical cancer cells.

RESULTS

In the present study, we reported that LMP2 and TAP2 levels were overexpressed in cervical cancer. Overexpression of LMP2 and TAP2 impaired the proliferation of Hela cells. In vivo studies substantiated that LMP2 and TAP2 antagonized tumor growth. Likewise, LMP2 and TAP2 overexpression decreased the migration and invasion ability of Hela cells by regulating the process of epithelial-mesenchymal transition (EMT). Mechanically, LMP2 and TAP2 subverted the protein abundance of Wnt1 and β-catenin, thereby downregulating their downstream targets Cyclin D1 and c-Myc. In addition, Wnt1 overexpression partially rescued the observed consequences of ectopic expression of LMP2 and TAP2 in cervical cancer cells. Taken together, our study revealed that LMP2 and TAP2 suppress the oncogenesis and metastasis of cervical cancer cells by Wnt/β-catenin pathway and altering EMT.

CONCLUSION

LMP2 and TAP2 may inhibit the oncogenesis and metastasis of cervical cancer cells by inhibiting the process of EMT and the Wnt/β-catenin signaling pathway, which may provide important insight into prospective targets for the treatment of cervical cancer.

Role of SIRT2 in intestinal barrier under cold exposure

Prolonged cold exposure causes body stress and damages health. The intestinal environment is complex and variable, and direct contact with the external environment can easily cause stress, damage and even lead to diseases such as diarrhea.

AIMS

This study aimed to reveal the role of cold exposure on ileum damage and the role of SIRT2 in this process.

MAIN METHODS

C57BL6 mice and SIRT2 knockout mice were used to construct a chronic cold exposure model (21 days, random 4 °C exposure for 3 h per day), which was tested by various methods, including intestinal permeability assays, morphological assays, ultrastructural assays, western blotting, and fluorescence staining. In vitro assays were performed on the mouse small intestinal epithelial cell line MODE-K to investigate the role of endoplasmic reticulum stress, SIRT2 knockout, and autophagy on tight junctions.

KEY FINDINGS

The results showed that chronic cold exposure damaged the ileal epithelial barrier, with endoplasmic reticulum stress. Knockout of SIRT2 alleviates ileal injury via enhanced autophagy under cold exposure. And autophagy can restore the expression of ZO-1 under stress.

SIGNIFICANCE

This study can provide potential target and basic data for the treatment of IBD and other disorders of the intestinal barrier. Autophagy may be an important means of restoring damage to the intestinal barrier.

Label-free quantitative proteomic analyses of mouse astrocytes provides insight into the host response mechanism at different developmental stages of Toxoplasma gondii

Toxoplasma gondii (T. gondii) is an opportunistic parasite that can infect the central nervous system (CNS), causing severe toxoplasmosis and behavioral cognitive impairment. Mortality is high in immunocompromised individuals with toxoplasmosis, most commonly due to reactivation of infection in the CNS. There are still no effective vaccines and drugs for the prevention and treatment of toxoplasmosis. There are five developmental stages for T. gondii to complete life cycle, of which the tachyzoite and bradyzoite stages are the key to the acute and chronic infection. In this study, to better understanding of how T. gondii interacts with the host CNS at different stages of infection, we constructed acute and chronic infection models of T. gondii in astrocytes, and used label-free proteomics to detect the proteome changes before and after infection, respectively. A total of 4676 proteins were identified, among which 163 differentially expressed proteins (fold change ≥ 1.5 or ≤ 0.67 and p-value ≤ 0.05) including 109 up-regulated proteins and 54 down-regulated proteins in C8-TA vs C8 group, and 719 differentially expressed proteins including 495 up-regulated proteins and 224 down-regulated proteins in C8-BR vs C8-TA group. After T. gondii tachyzoites infected astrocytes, differentially expressed proteins were enriched in immune-related biological processes to promote the formation of bradyzoites and maintain the balance of T. gondii, CNS and brain. After T. gondii bradyzoites infected astrocytes, the differentially expressed proteins up-regulated the host's glucose metabolism, and some up-regulated proteins were strongly associated with neurodegenerative diseases. These findings not only provide new insights into the psychiatric pathogenesis of T. gondii, but also provide potential targets for the treatment of acute and chronic Toxoplasmosis.

Silencing of purinergic receptor P2Y2 inhibited enteric neural crest cell proliferation, invasion and migration via suppressing ERK signaling pathway in Hirschsprung disease

The current study aimed to explore the effect and underlying mechanism of the purinergic receptor P2Y2 in regulating the loss of intestinal neurons and the intestinal neural crest in Hirschsprung's disease (HSCR). Western blotting was used to assess the expression levels of P2Y2 in colon tissues. An in vivo HSCR mouse model was established following treatment with benzalkonium chloride (BAC). We overexpressed or silenced P2Y2 in SH-SY5Y cells, and cell proliferation, migration, and invasion were subsequently investigated by CCK-8, wound healing, and transwell assays, respectively. Additionally, we implemented a xenograft model to assess the impact of P2Y2 on tumor growth as well as the expression of extracellular signal-regulated kinase (ERK). The results showed that the expression of P2Y2 protein in the colon tissues of patients with HSCR was lower than that in the normal colon tissues. P2Y2 expression is downregulated in the colon tissues of mice with HSCR. Additionally, P2Y2 silencing inhibited SH-SY5Y cell proliferation, invasion, and migration. Furthermore, adenosine 5'-triphosphate (ATP, a strong agonist of P2Y2)-induced P2Y2 overexpression enhanced the proliferation, invasion, and migration of SH-SY5Y cells. Immunofluorescence staining and western blot analysis revealed that P2Y2 silencing downregulated phosphorylated (p)-ERK in SH-SY5Y cells. In addition, treatment with PD98059, a p-ERK inhibitor, reversed the effects of ATP on SH-SY5Y cell proliferation, invasion, and migration. Finally, we demonstrated that P2Y2 silencing suppressed tumor growth and decreased p-ERK expression. Overall, the results of the present study suggest that P2Y2 plays an important role in HSCR pathogenesis. P2Y2 silencing inhibited the proliferation, invasion, and migration of nerve cells by suppressing the ERK signaling pathway. P2Y2 silencing could be considered an innovative and possible target for treating HSCR.

Stem cell-derived intestinal organoids: a novel modality for IBD

The organoids represent one of the greatest revolutions in the biomedical field in the past decade. This three-dimensional (3D) micro-organ cultured in vitro has a structure highly similar to that of the tissue and organ. Using the regeneration ability of stem cells, a 3D organ-like structure called intestinal organoids is established, which can mimic the characteristics of real intestinal organs, including morphology, function, and personalized response to specific stimuli. Here, we discuss current stem cell-based organ-like 3D intestinal models, including understanding the molecular pathophysiology, high-throughput screening drugs, drug efficacy testing, toxicological evaluation, and organ-based regeneration of inflammatory bowel disease (IBD). We summarize the advances and limitations of the state-of-the-art reconstruction platforms for intestinal organoids. The challenges, advantages, and prospects of intestinal organs as an in vitro model system for precision medicine are also discussed. Key applications of stem cell-derived intestinal organoids. Intestinal organoids can be used to model infectious diseases, develop new treatments, drug screens, precision medicine, and regenerative medicine.

SIRT2 Deficiency Aggravates Diet-Induced Nonalcoholic Fatty Liver Disease through Modulating Gut Microbiota and Metabolites

Non-alcoholic fatty liver disease (NAFLD), characterized by excessive lipid accumulation in hepatocytes, is an increasing global healthcare burden. Sirtuin 2 (SIRT2) functions as a preventive molecule for NAFLD with incompletely clarified regulatory mechanisms. Metabolic changes and gut microbiota imbalance are critical to the pathogenesis of NAFLD. However, their association with SIRT2 in NAFLD progression is still unknown. Here, we report that SIRT2 knockout (KO) mice are susceptible to HFCS (high-fat/high-cholesterol/high-sucrose)-induced obesity and hepatic steatosis accompanied with an aggravated metabolic profile, which indicates SIRT2 deficiency promotes NAFLD-NASH (nonalcoholic steatohepatitis) progression. Under palmitic acid (PA), cholesterol (CHO), and high glucose (Glu) conditions, SIRT2 deficiency promotes lipid deposition and inflammation in cultured cells. Mechanically, SIRT2 deficiency induces serum metabolites alteration including upregulation of L-proline and downregulation of phosphatidylcholines (PC), lysophosphatidylcholine (LPC), and epinephrine. Furthermore, SIRT2 deficiency promotes gut microbiota dysbiosis. The microbiota composition clustered distinctly in SIRT2 KO mice with decreased Bacteroides and Eubacterium, and increased Acetatifactor. In clinical patients, SIRT2 is downregulated in the NALFD patients compared with healthy controls, and is associated with exacerbated progression of normal liver status to NAFLD to NASH in clinical patients. In conclusion, SIRT2 deficiency accelerates HFCS-induced NAFLD-NASH progression by inducing alteration of gut microbiota and changes of metabolites.

Orchestration of MUC2 - The key regulatory target of gut barrier and homeostasis: A review

The gut mucosa of human is covered by mucus, functioning as a crucial defense line for the intestine against external stimuli and pathogens. Mucin2 (MUC2) is a subtype of secretory mucins generated by goblet cells and is the major macromolecular component of mucus. Currently, there is an increasing interest on the investigations of MUC2, noting that its function is far beyond a maintainer of the mucus barrier. Moreover, numerous gut diseases are associated with dysregulated MUC2 production. Appropriate production level of MUC2 and mucus contributes to gut barrier function and homeostasis. The production of MUC2 is regulated by a series of physiological processes, which are orchestrated by various bioactive molecules, signaling pathways and gut microbiota, etc., forming a complex regulatory network. Incorporating the latest findings, this review provided a comprehensive summary of MUC2, including its structure, significance and secretory process. Furthermore, we also summarized the molecular mechanisms of the regulation of MUC2 production aiming to provide developmental directions for future researches on MUC2, which can act as a potential prognostic indicator and targeted therapeutic manipulation for diseases. Collectively, we elucidated the micro-level mechanisms underlying MUC2-related phenotypes, hoping to offer some constructive guidance for intestinal and overall health of mankind.

Disrupted metabolic signatures in amniotic fluid associated with increased risk of intestinal inflammation in cesarean section offspring

Introduction

Children born by cesarean section (CS) are at a greater risk of inflammatory bowel disease (IBD). However, the mechanisms underlying the association are not yet well understood. Herein, we investigated the impact of CS delivery on colonic inflammation and mechanisms underlying these effects in offspring.

Methods

CS mice model and dextran sulfate sodium (DSS)-induced colitis model were constructed and used to analyze the impact of CS on the development of colitis. Colonic tight junction markers and epithelium differentiation markers were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Levels of zonulin in serum were detected by enzyme-linked immunosorbent assay (ELISA). Immune cells in colon were analyzed by flow cytometry. Metabolic profiling between human vaginal delivery (VD) and CS AF were analyzed by using mass spectrometry. Transcriptome changes between VD AF- and CS AF-treated human intestine epithelial cells were analyzed by RNA-sequencing. A multi-omics approach that integrated transcriptomics with metabolomics to identify the pathways underlying colonic inflammation associated with delivery modes. Then, the identified pathways were confirmed by immunoblotting and ELISA.

Results

Mice pups delivered by CS exhibited a defective intestinal homeostasis manifested by decreased expression of tight junction markers of ZO-1 and Occludin in the colons, increased levels of zonulin in serum and dysregulated expression of intestinal epithelium differentiation markers of Lysozyme, Mucin2, and Dipeptidyl peptidase-4. CS pups were more susceptible to DSS-induced colitis compared to VD pups. The proportion of macrophage, dendritic cells (DCs), and natural killer cells (NKs) in the colons were altered in an age-dependent manner compared with pups born naturally. The metabolites in AF differed between CS and VD cases, and the CS AF-induced differentially expressed genes (DEGs) were significantly enriched in pathways underlying IBD. Signal transducer and activator of transcription 3 (STAT3) signaling was downregulated in NCM460 intestinal epithelial cells by CS AF compared to VD AF and in colon of CS pups compared to VD pups. Deficiency in metabolites like vitamin D2 glucosiduronate in CS AF may attribute to the risk of inflammatory intestine through STAT3 signaling.

Conclusion

Our study provides a novel insight into the underlying mechanisms of CS-associated intestinal inflammation and potential prevention strategies.

The sirtuin family in health and disease

Sirtuins (SIRTs) are nicotine adenine dinucleotide(+)-dependent histone deacetylases regulating critical signaling pathways in prokaryotes and eukaryotes, and are involved in numerous biological processes. Currently, seven mammalian homologs of yeast Sir2 named SIRT1 to SIRT7 have been identified. Increasing evidence has suggested the vital roles of seven members of the SIRT family in health and disease conditions. Notably, this protein family plays a variety of important roles in cellular biology such as inflammation, metabolism, oxidative stress, and apoptosis, etc., thus, it is considered a potential therapeutic target for different kinds of pathologies including cancer, cardiovascular disease, respiratory disease, and other conditions. Moreover, identification of SIRT modulators and exploring the functions of these different modulators have prompted increased efforts to discover new small molecules, which can modify SIRT activity. Furthermore, several randomized controlled trials have indicated that different interventions might affect the expression of SIRT protein in human samples, and supplementation of SIRT modulators might have diverse impact on physiological function in different participants. In this review, we introduce the history and structure of the SIRT protein family, discuss the molecular mechanisms and biological functions of seven members of the SIRT protein family, elaborate on the regulatory roles of SIRTs in human disease, summarize SIRT inhibitors and activators, and review related clinical studies.

Glycolytic Regulation of Intestinal Stem Cell Self-Renewal and Differentiation

BACKGROUND AND AIMS

The intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis. An imbalance in this highly regimented process within the intestinal crypts is associated with several intestinal pathologies. Although metabolic changes are known to play a pivotal role in cell proliferation and differentiation, how glycolysis contributes to intestinal epithelial homeostasis remains to be defined.

METHODS

Small intestines were harvested from mice with specific hexokinase 2 (HK2) deletion in the intestinal epithelium or LGR5+ stem cells. Glycolysis was measured using the Seahorse XFe96 analyzer. Expression of phospho-p38 mitogen-activated protein kinase, the transcription factor atonal homolog 1, and intestinal cell differentiation markers lysozyme, mucin 2, and chromogranin A were determined by Western blot, quantitative real-time reverse transcription polymerase chain reaction, or immunofluorescence, and immunohistochemistry staining.

RESULTS

HK2 is a target gene of Wnt signaling in intestinal epithelium. HK2 knockout or inhibition of glycolysis resulted in increased numbers of Paneth, goblet, and enteroendocrine cells and decreased intestinal stem cell self-renewal. Mechanistically, HK2 knockout resulted in activation of p38 mitogen-activated protein kinase and increased expression of ATOH1; inhibition of p38 mitogen-activated protein kinase signaling attenuated the phenotypes induced by HK2 knockout in intestinal organoids. HK2 knockout significantly decreased glycolysis and lactate production in intestinal organoids; supplementation of lactate or pyruvate reversed the phenotypes induced by HK2 knockout.

CONCLUSIONS

Our results show that HK2 regulates intestinal stem cell self-renewal and differentiation through p38 mitogen-activated protein kinase/atonal homolog 1 signaling pathway. Our findings demonstrate an essential role for glycolysis in maintenance of intestinal stem cell function.

Aloin A prevents ulcerative colitis in mice by enhancing the intestinal barrier function via suppressing the Notch signaling pathway

BACKGROUND

Previous studies reported that Aloe vera ameliorated DSS-induced colitis and promoted mucus secretion. However, the effect of Aloin A (AA), a major compound of Aloe vera, on colitis and its exact mechanism remains uncovered.

METHODS

C57BL/6 mice were successively subjected to 3% DSS solution for 5 days and distilled water for 2 days. Concurrently, AA (25, 50 mg/kg) and 5-aminosalicylic (500 mg/kg) were administrated intragastrically from day 1 to day 7. Colitis was evaluated by disease active index (DAI), colon length, inflammation response, and intestinal barrier function. In vitro LS174T cells challenged with 50 ng/ml of lipopolysaccharides (LPS) were used to validate the modulatory action of AA on the Notch signaling pathway.

RESULTS

Our results showed that oral administration with AA prominently prevented DSS-induced colitis symptoms in terms of decreased DAI, prevention of colon shortening, and reduced pathological damage. AA mitigated the inflammatory response evidenced by the decreased proinflammatory cytokines (TNF-α, IL-1β, IL-6) and increased anti-inflammatory cytokine (IL-10). Besides, AA inhibited apoptosis and facilitated proliferation in colons. Moreover, AA treatment up-regulated the expression of tight junction (TJ) proteins (ZO-1, Occludin) and promoted the secretion of MUC2 to decrease colon permeability. Mechanistically, AA inhibited the Notch pathway to promote the secretion of MUC2, which was consistent with LPS-challenged LS174 cells.

CONCLUSION

These results suggested that AA could prevent colitis by enhancing the intestinal barrier function via suppressing the Notch signaling pathway. Thus, AA might be a prospective remedy for ulcerative colitis.

Cold exposure-induced endoplasmic reticulum stress regulates autophagy through the SIRT2/FoxO1 signaling pathway

Cold is a factor affecting health in humans and animals. The liver, a major metabolic center, is highly susceptible to ambient air temperature. Recent studies have shown that endoplasmic reticulum (ER) stress is associated with the liver, and regulates the occurrence and development of liver injury and autophagy. However, the mechanism underlying the relationship between cold exposure and ER stress in the liver is not well understood. In this study, we investigated the effect of ER stress on liver autophagy and its mechanism under cold exposure. AML12 cells were treated with Tg to construct an ER stress model, and the level of autophagy increased. To further explore the mechanism through which ER stress regulates autophagy, we knocked down SIRT2 with shRNA in Tg-treated AML12 cells. Knockdown of SIRT2 significantly increased ER stress and autophagy, increased FoxO1 acetylation, and promoted its entry into the nucleus. To further verify the results of in vitro experiments, we exposed mice to 4°C for 3 h per day for 3 weeks to exacerbate the burden on the liver after cold exposure. Cold exposure damaged the structure and function of the liver and promoted the inflammatory response. It also activated ER stress and promoted autophagy. In addition, cold exposure inhibited the expression of SIRT2, promoted FoxO1 acetylation, and enhanced the interaction with autophagy. Our findings indicated that cold exposure induces liver damage, ER stress, and autophagy through the SIRT2/FoxO1 pathway. These findings suggest that SIRT2 may be a potential target for regulating health under cold exposure.

Inhibition of GABAAR or Application of Lactobacillus casei Zhang Alleviates Ulcerative Colitis in Mice: GABAAR as a Potential Target for Intestinal Epithelial Renewal and Repair

Emerging evidence indicates that the gamma−aminobutyric acid type A receptor (GABA_AR) and Lactobacillus casei Zhang regulate colitis in a variety of ways, such as by participating in host immune and inflammatory responses, altering the gut microbiota, and influencing intestinal barrier function. However, not much is known about the mechanisms by which GABA_AR and L. casei affect colon epithelial cell renewal and the interaction between GABA_AR and L. casei during this process. To elucidate this, we established a dextran sulfate sodium (DSS)−induced model and measured the mouse body weights, colon length, the disease activity index (DAI), and histological scores. Our results indicated that inhibition of GABA_AR alleviated the DSS−induced colitis symptoms, resulting in less weight loss and more intact colon tissue. Moreover, treatment with bicuculline (Bic, a GABA_AR inhibitor) increased the levels of PCNA, β−catenin, and TCF4 in mice with colitis. Interestingly, open field test performances showed that inhibition of GABA_AR also attenuated colitis−related anxiety−like behavior. By 16S RNA gene sequencing analysis, we showed that inhibition of GABA_AR partially reversed the gut dysbacteriosis of DSS−induced mice and increased the abundance of beneficial bacteria. Additionally, L. casei Zhang supplementation inhibited the expression of GABA_AR in mice with colitis, promoted the proliferation and renewal of colon epithelial cells, and alleviated anxiety−like behavior and intestinal microflora disorder in mice. Thus, GABA_AR plays a key role in the beneficial effects of L. casei on DSS−induced colitis in mice.

Interleukin-22 Ameliorates Dextran Sulfate Sodium-Induced Colitis through the Upregulation of lncRNA-UCL to Accelerate Claudin-1 Expression via Sequestering miR-568 in Mice

Background

Bioactive compound such as interleukin-22 (IL-22) treatment is regarded as a sufficient treatment for ulcerative colitis (UC). It has been found that long noncoding RNAs (lncRNAs) expressed in many inflammatory diseases, including UC. We aimed to verify the treatment effect of bioactive compounds including IL-22 and lncRNAs in UC on colitis mice.

Methods

UC mice were induced using DSS, followed by IL-22 or PBS intraperitoneally (i.p.) injection. Then, the histopathological parameters of the mice were determined. Then, RNA sequencing was performed to screen the differential lncRNAs. Quantitative real-time PCR (qRT-PCR) and lentivirus identified lncRNA-Ulcerative Colitis lncRNA (lncRNA-UCL) were regarded as the molecular regulator of the colitis mice. The correlation with lncRNA-UCL and mmu-miR-568 was validated using RNA-pulldown. Meanwhile, claudin-1 was predicted and confirmed as the target molecule of mmu-miR-568 using dual-luciferase assay.

Results

IL-22 could significantly improve the histopathological features and decrease proinflammatory cytokine production in UC mice induced by DSS. It also can stimulate intestinal epithelial cell (IEC) reproduction and prevention of apoptosis. lncRNA-UCL was significantly downregulated in UC mice caused by DSS, while IL-22 treatment effectively reversed this effect. In terms of mechanism, lncRNA-UCL regulates intestinal epithelial homeostasis by sequestering mmu-miR-568 and maintaining close integrated protein expression, such as claudin-1.

Conclusions

We have demonstrated the incredible role of bioactive compound, such as IL-22, in alleviating DSS-induced colitis symptoms via enhancing lncRNA-UCL expression. It can be regulated using tight junction (TJ) protein.

The Therapeutic Relevance of Urolithins, Intestinal Metabolites of Ellagitannin-Rich Food: A Systematic Review of In Vivo Studies

The therapeutic effects of food rich in ellagitannins have been established to stem from its microbial metabolite, urolithin. Over the past decade, there has been a growing trend in urolithin research pertaining to its pharmacological properties. The purpose of this systematic review is to collate and synthesise all available data on urolithin’s therapeutic ability, to highlight its potential as a pharmaceutical agent, and prospective direction on future research. Methods: This systematic review was written based on the PRISMA guideline and was conducted across Ovid via Embase, Ovid MEDLINE, Cochrane Central Register for Controlled Trials, and Web of Science Core Collection. Results: A total of 41 animal studies were included in this systematic review based on the appropriate keyword. The included studies highlighted the neuroprotective, anti-metabolic disorder activity, nephroprotective, myocardial protective, anti-inflammatory, and musculoskeletal protection of urolithin A, B, and its synthetic analogue methylated urolithin A. The Sirt1, AMPK, and PI3K/AKT/mTOR signalling pathways were reported to be involved in the initiation of autophagy and mitochondrial biogenesis by urolithin A. Conclusions: This review methodically discusses the therapeutic prospects of urolithins and provides scientific justification for the potential development of urolithin A as a potent natural mitophagy inducer for anti-ageing purposes.

Associations of serum vitamin D and Fok I polymorphism of receptor gene with unexplained recurrent spontaneous abortion

Background: To investigate the associations of serum vitamin D and Fok I polymorphism of its receptor (VDR) with unexplained recurrent spontaneous abortion (URSA).

Methods: Ninety URSA patients and another 104 healthy pregnant women were selected as URSA and control groups, respectively. 25-Hydroxyvitamin D [25-(OH)D] level was detected by chemiluminescence. VDR gene Fok I polymorphism was analyzed by PCR, and the distribution of genotype frequency was calculated by Hardy-Weinberg equilibrium test. Association between Fok I polymorphism and susceptibility to URSA was investigated by logistic regression analysis.

Results: Gestational age, uterine height, waist circumference, 25-(OH)D level and proportions of Fok I FF and Ff genotypes were significantly lower in the URSA group (P<0.05). Compared with ff genotype, risk of URSA reduced for Ff and FF genotypes. Compared with allele f, risk of URSA was lower for allele F. 25-(OH)D level of ff genotype was significantly lower in the URSA group, which was lower than that of FF genotype (P<0.05). Compared with women with 25-(OH)D level >30 ng/mL and F allele (FF+Ff), the risk of URSA increased 2.45-, 2.43- and 5.34-fold for those with 25-(OH)D level >30 ng/mL and ff genotype, with 25-(OH)D level ≤30 ng/mL, and with ff genotype and 25-(OH)D level ≤30 ng/mL, respectively.

Conclusions: The 25-(OH)D level of the URSA group was significantly lower than that of normal pregnant women. Probably, VDR gene Fok I polymorphism is associated with URSA occurrence, and allele F decreases the risk. The risk of URSA dramatically increases in women with ff genotype and 25-(OH)D deficiency.

Patient-derived organoids for therapy personalization in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the intestinal tract that have emerged as a growing problem in industrialized countries. Knowledge of IBD pathogenesis is still incomplete, and the most widely-accepted interpretation considers genetic factors, environmental stimuli, uncontrolled immune responses and altered intestinal microbiota composition as determinants of IBD, leading to dysfunction of the intestinal epithelial functions. In vitro models commonly used to study the intestinal barrier do not fully reflect the proper intestinal architecture. An important innovation is represented by organoids, 3D in vitro cell structures derived from stem cells that can self-organize into functional organ-specific structures. Organoids may be generated from induced pluripotent stem cells or adult intestinal stem cells of IBD patients and therefore retain their genetic and transcriptomic profile. These models are powerful pharmacological tools to better understand IBD pathogenesis, to study the mechanisms of action on the epithelial barrier of drugs already used in the treatment of IBD, and to evaluate novel target-directed molecules which could improve therapeutic strategies. The aim of this review is to illustrate the potential use of organoids for therapy personalization by focusing on the most significant advances in IBD research achieved through the use of adult stem cells-derived intestinal organoids.

Dietary High Dose of Iron Aggravates the Intestinal Injury but Promotes Intestinal Regeneration by Regulating Intestinal Stem Cells Activity in Adult Mice With Dextran Sodium Sulfate-Induced Colitis

The effects of excessive dietary iron intake on the body have been an important topic. The purpose of this study was to investigate the effects of high-dose iron on intestinal damage and regeneration in dextran sodium sulfate (DSS)-induced colitis model mice. A total of 72 8-week-old adult C57BL/6 mice were randomly divided into two dietary treatment groups: the basal diet supplemented with 45 (control) and 450 mg/kg iron (high-iron) from ferrous sulfate. The mice were fed different diets for 2 weeks, and then 2.5% DSS was orally administered to all mice for 7 days. Samples of different tissues were collected on days 0, 3, and 7 post administration (DPA). High-iron treatment significantly decreased the relative weight of the large intestine at 7 DPA but not at 0 DPA or 3 DPA. High dietary iron increased the jejunal villus width at 0 DPA, decreased the villus width and the crypt depth of the jejunum at 3 DPA, and decreased the number of colonic crypts at 7 DPA. Meanwhile, high dietary iron decreased the number of goblet cells in the jejunal villi and the Paneth cells in the jejunal crypts at 0 DPA, increased the number of goblet cells per crypt of the colon at 3 DPA, and the number of Paneth cells in the jejunal crypts, the goblet cells in the colon, the Ki67-positive proliferating cells in the colon, and the Sex-determining region Y-box transcription factor 9⁺ (SOX9) cells in the jejunum crypts and colon at 7 DPA. The organoid formation rate was increased by high-iron treatments at 3 DPA and 7 DPA. High dietary iron treatment decreased the mRNA level of jejunal jagged canonical Notch ligand 2 (Jag-2) at 0 DPA and bone morphogenetic protein 4 (Bmp4) and neural precursor cell-expressed developmentally downregulated 8 (Nedd8) in the jejunum and colon at 7 DPA, whereas it increased the mRNA expression of the serum/glucocorticoid-regulated kinase 1 (Sgk1) in the colon at 3 DPA. The results suggested that a high dose of iron aggravated intestinal injury but promoted intestinal repair by regulating intestinal epithelial cell renewal and intestinal stem cell activity in adult mice with colitis.

Association of sirtuins (SIRT1-7) with lung and intestinal diseases

"Exterior-interior correlation between the lung and large intestine" is one of the important contents of traditional Chinese medicine. This theory describes the role of the lung and the intestine in association with disease treatment. The "lung-gut" axis is a modern extension of the "exterior-interior correlation between lung and large intestine" theory in TCM. Sirtuin (SIRT) is a nicotinamide adenine dinucleotide (NAD⁺)-dependent enzyme family with deacetylase properties, which is highly conserved from bacteria to humans. The sirtuin defines seven silencing regulatory proteins (SIRT1-7) in human cells. It can regulate aging, metabolism, and certain diseases. Current studies have shown that sirtuins have dual characteristics, acting as both tumor promoters and tumor inhibitors in cancers. This paper provides a comparative summary of the roles of SIRT1-7 in the intestine and lung (both inflammatory diseases and tumors), and the promoter/suppressor effects of targeting SIRT family microRNAs and modulators of inflammation or tumors. Sirtuins have great potential as drug targets for the treatment of intestinal and respiratory diseases. Meanwhile, it may provide new ideas of future drug target research.

Gut microbiota: sculptors of the intestinal stem cell niche in health and inflammatory bowel disease

Intestinal epithelium represents a dynamic and diverse cellular system that continuously interacts with gut commensals and external cues. Intestinal stem cells, which lie at the heart of epithelial renewal and turnover, proliferate to maintain a steady stem cell population and differentiate to form functional epithelial cell types. This rather sophisticated assembly-line is maintained by an elaborate micro-environment, sculpted by a myriad of host and gut microbiota-derived signals, forming an intestinal stem cell niche. This complex, yet crucial signaling niche undergoes dynamic changes during homeostasis and chronic intestinal inflammation. Inflammatory bowel disease refers to a chronic inflammatory response toward pathogenic or commensal microbiota, in a genetically susceptible host. Compositional and functional alterations in gut microbiota are pathognomonic of IBD.The present review highlights the modulatory role of gut microbiota on the intestinal stem cell niche during homeostasis and inflammatory bowel disease. We discuss the mechanisms of direct action of gut commensals (through microbiota-derived or microbiota-influenced metabolites) on ISCs, followed by their effects via other epithelial and immune cell types.

The interaction of canonical Wnt/β-catenin signaling with protein lysine acetylation

Canonical Wnt/β-catenin signaling is a complex cell-communication mechanism that has a central role in the progression of various cancers. The cellular factors that participate in the regulation of this signaling are still not fully elucidated. Lysine acetylation is a significant protein modification which facilitates reversible regulation of the target protein function dependent on the activity of lysine acetyltransferases (KATs) and the catalytic function of lysine deacetylases (KDACs). Protein lysine acetylation has been classified into histone acetylation and non-histone protein acetylation. Histone acetylation is a kind of epigenetic modification, and it can modulate the transcription of important biological molecules in Wnt/β-catenin signaling. Additionally, as a type of post-translational modification, non-histone acetylation directly alters the function of the core molecules in Wnt/β-catenin signaling. Conversely, this signaling can regulate the expression and function of target molecules based on histone or non-histone protein acetylation. To date, various inhibitors targeting KATs and KDACs have been discovered, and some of these inhibitors exert their anti-tumor activity via blocking Wnt/β-catenin signaling. Here, we discuss the available evidence in understanding the complicated interaction of protein lysine acetylation with Wnt/β-catenin signaling, and lysine acetylation as a new target for cancer therapy via controlling this signaling.

Gut metabolite Urolithin A mitigates ionizing radiation-induced intestinal damage

Ionizing radiation (IR)‐induced intestinal damage is the major and common injury of patients receiving radiotherapy. Urolithin A (UroA) is a metabolite of the intestinal flora of ellagitannin, a compound found in fruits and nuts such as pomegranates, strawberries and walnuts. UroA shows the immunomodulatory and anti‐inflammatory capacity in various metabolic diseases. To evaluate the radioprotective effects, UroA(0.4, 2 and 10 mg/kg) were intraperitoneally injected to C57BL/6 male mice 48, 24, 1 h prior to and 24 h after 9.0Gy TBI. The results showed that UroA markedly upregulated the survival of irradiated mice, especially at concentration of 2 mg/kg. UroA improved the intestine morphology architecture and the regeneration ability of enterocytes in irradiated mice. Then, UroA significantly decreased the apoptosis of enterocytes induced by radiation. Additionally, 16S rRNA sequencing analysis showed the effect of UroA is associated with the recovery of the IR‐induced intestinal microbacteria profile changes in mice. Therefore, our results determinated UroA could be developed as a potential candidate for radiomitigators in radiotherapy and accidental nuclear exposure. And the beneficial functions of UroA might be associated with the inhibition of p53‐mediated apoptosis and remodelling of the gut microbes.

Neurotensin Regulates Proliferation and Stem Cell Function in the Small Intestine in a Nutrient-Dependent Manner

BACKGROUND & AIMS

Intestinal stem cells (ISCs) are sensitive to dietary alterations and nutrient availability. Neurotensin (NT), a gut peptide localized predominantly to the small bowel and released by fat ingestion, stimulates the growth of intestinal mucosa under basal conditions and during periods of nutrient deprivation, suggesting a possible role for NT on ISC function.

METHODS

Leucine-rich repeat-containing G-protein coupled receptor 5-Enhanced Green Fluorescent Protein (Lgr5-EGFP) NT wild type (Nt^+/+) and Lgr5-EGFP NT knockout (Nt^-/-) mice were fed ad libitum or fasted for 48 hours. Small intestine tissue and crypts were examined by gene expression analyses, fluorescence-activated cell sorting, Western blot, immunohistochemistry, and crypt-derived organoid culture. Drosophila expressing NT in midgut enteroendocrine cells were fed a standard diet or low-energy diet and esg-green fluorescent protein⁺ ISCs were quantified via immunofluorescence.

RESULTS

Loss of NT impaired crypt cell proliferation and ISC function in a manner dependent on nutrient status. Under nutrient-rich conditions, NT stimulated extracellular signal-regulated kinases 1 and 2 signaling and the expression of genes that promote cell-cycle progression, leading to crypt cell proliferation. Under conditions of nutrient depletion, NT stimulated WNT/β-catenin signaling and promoted an ISC gene signature, leading to enhanced ISC function. NT was required for the induction of WNT/β-catenin signaling and ISC-specific gene expression during nutrient depletion, and loss of NT reduced crypt cell proliferation and impaired ISC function and Lgr5 expression in the intestine during fasting. Conversely, the expression of NT in midgut enteroendocrine cells of Drosophila prevented loss of ISCs during nutrient depletion.

CONCLUSIONS

Collectively, our findings establish an evolutionarily conserved role for NT in ISC maintenance during nutritional stress. GSE182828.

Analysis of Sirtuin 1 and Sirtuin 3 at Enzyme and Protein Levels in Human Breast Milk during the Neonatal Period

Breast feeding is regarded as the preferred nutrition modality for children during the first few months of life. It not only furthers growth and development but also is supposed to impact later life. The first 1000 days are regarded as a critical window for development, even beyond infancy. The physiological basis underlying this beneficial effect is not clear. Sirtuins are important regulatory proteins of metabolism and are supposed to play a critical role in ageing and longevity as well as in diseases. In the present study, we developed novel methods to assay sirtuin 1 and sirtuin 3 at enzyme activity (via fluorometry) and protein levels (by Western blot) in the aqueous phase and in the cell pellet of human breast milk and assessed the impact of ongoing lactation during the neonatal period. Sirtuin activities in the aqueous phase were negatively correlated with the duration of lactation in the neonatal period. There was no correlation of sirtuin activities in the cell pellet with the duration of lactation. The amounts of sirtuin 1 and sirtuin 3 measured by Western blot were negatively correlated with the lactation period.

Regulation of SIRT2 by Wnt/β-catenin signaling pathway in colorectal cancer cells

Activation of the Wnt/β-catenin pathway is one of the hallmarks of colorectal cancer (CRC). Sirtuin 2 (SIRT2) protein has been shown to inhibit CRC proliferation. Previously, we reported that SIRT2 plays an important role in the maintenance of normal intestinal cell homeostasis. Here, we show that SIRT2 is a direct target gene of Wnt/β-catenin signaling in CRC cells. Inhibition or knockdown of Wnt/β-catenin increased SIRT2 promoter activity and mRNA and protein expression, whereas activation of Wnt/β-catenin decreased SIRT2 promoter activity and expression. β-Catenin was recruited to the promoter of SIRT2 and transcriptionally regulated SIRT2 expression. Wnt/β-catenin inhibition increased mitochondrial oxidative phosphorylation (OXPHOS) and CRC cell differentiation. Moreover, inhibition of OXPHOS attenuated the differentiation of CRC cells induced by Wnt/β-catenin inhibition. In contrast, inhibition or knockdown of SIRT2 decreased, while overexpression of SIRT2 increased, OXPHOS activity and differentiation in CRC cells. Consistently, inhibition or knockdown or SIRT2 attenuated the differentiation induced by Wnt/β-catenin inhibition. These results demonstrate that SIRT2 is a novel target gene of the Wnt/β-catenin signaling and contributes to the differentiation of CRC cells.

Thiomyristoyl ameliorates colitis by blocking the differentiation of Th17 cells and inhibiting SIRT2-induced metabolic reprogramming

BACKGROUND

The pathogenesis of inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC) has not been fully elucidated. However, a strong correlation between IBD and high T helper 17 (Th17) levels has been found. Sirtuin 2 (SIRT2) has recently been found to play an important role in metabolic reprogramming, but its potential anti-inflammatory properties remain unclear.

METHODS

The expression levels of SIRT2 and glucose metabolism-related proteins in peripheral blood mononuclear cells (PBMCs) of IBD patients and healthy volunteers were detected. Human PBMCs were differentiated into Th17 cells in vitro and were treated with TM simultaneously. The ratio of Th17 cells and apoptotic cells and the production of Interleukin (IL)-17A and the expression levels of transcription factors of classical signaling pathway related to Th17 differentiation were determined. The acetylation of LDHA and glucose metabolism was assessed. Subsequently, C57BL/6J colitis mice induced by 2.5% dextran sulfatesodiumsalt (DSS) were treated with or without TM, Disease activity index, T cell subsets in the mice spleen, relevant inflammatory cytokines in serum, specific mRNA, and proteins in mice colon were evaluated respectively.

RESULTS

SIRT2 and glucose metabolism-related proteins in PBMCs of patients were overexpressed. Compared with the positive control group, human PBMCs treated with TM had lower levels of IL-17A, percentage of Th17 cells, levels of phospho-signal transducer and activator of transcription (p-STAT) 3 and phospho-nuclear transcription factor-κB (p-NF-κB), but higher levels of acetylated LDHA. Compared with colitis mice, TM-treated colitis mice had longer colons, reduced weight-losses, and lower disease activity index and histopathologic scores. Interestingly, although the expression levels of interferon (IFN)-γ, IL-17A, and retinoic acid receptor-related orphan receptor (ROR)-γt were inhibited in the colons of TM-treated colitis mice, the expression of forkhead box protein P3 (FOXP3) didn't change. Consistently, relative to the high percentage of splenic Th17 cells in colitis mice, the percentage of splenic Th17 cells in TM-treated colitis mice was as normal as PBS-treated mice, while the percentage of Treg cells was not affected. Additionally, the TM group had reduced levels of IL-23 and hypoxiainduciblefactor-1α (HIF-1α), and an increased level of IL-10 in the colon, compared with the colitis group.

CONCLUSION

Our results indicate that TM reduces UC progression by reducing metabolic reprogramming and T cell differentiation. Specifically, TM prevented Th17 differentiation by reducing the expression of related transcription factors and promoting acetylation of LDHA (weakening glycolysis). SIRT2 may be a potential target for IBD treatment.