c-Jun N-terminal kinase 2 promotes enterocyte survival and goblet cell differentiation in the inflamed intestine

Intestinal Epithelial Responses to IL-17 in Adult Stem Cell-derived Human Intestinal Organoids

BACKGROUND

Th17 cells and their signature cytokine, interleukin-17A [IL-17], are considered as the main pathogenic factors in inflammatory bowel diseases [IBDs]. However, IL-17 neutralising antibodies, a theoretically curative medication for IBDs, paradoxically aggravated intestinal inflammation. The mechanisms by which IL-17 mediates the protective and pathological effects of IL-17 remain unclear in the intestinal epithelium.

METHODS

The intestinal epithelial responses induced by IL-17 were evaluated using the human small intestinal organoid [enteroid] model.

RESULTS

Organoid-forming efficiency, cell viability, and proliferation of enteroids were decreased in proportion to IL-17 concentration. The IL-17 induced cytotoxicity was predominantly mediated by pyroptosis with activation of CASP1 and cleavage of GSDMD. Bulk RNA-sequencing revealed the enrichment of secretion signalling in IL-17 treated enteroids, leading to mucin exocytosis. Among its components, PIGR was up-regulated significantly as the concentration of IL-17 increased, resulting in IgA transcytosis. Mucin exocytosis and IgA transcytosis have a protective role against enteric pathogens. Single-cell RNA sequencing identified that CASP1-mediated pyroptosis occurred actively in intestinal stem cells [ISCs] and enterocytes. IL-17 neutralising antibody completely restored IL-17 induced cytotoxicity, but suppressed mucin secretion and IgA transcytosis. Pyroptosis inhibition using CASP1 inhibitors significantly improved IL-17 induced cytotoxicity without diminishing its beneficial effects.

CONCLUSIONS

IL-17 induces the pyroptosis of ISCs and enterocytes, as well as mucin secretion of goblet cells and IgA transcytosis of epithelial cells. Paradoxical gastrointestinal effects of IL-17 neutralising antibodies may be associated with inhibition of mucin secretion and IgA transcytosis. The inhibition of pyroptosis using CASP1 inhibitors prevents IL-17 induced cytotoxicity without compromising its beneficial effects.

Crosstalk between incretin hormones, Th17 and Treg cells in inflammatory diseases

Intestinal epithelial cells constantly crosstalk with the gut microbiota and immune cells of the gut lamina propria. Enteroendocrine cells, secrete hormones, such as incretin hormones, which participate in host physiological events, such as stimulating insulin secretion, satiety, and glucose homeostasis. Interestingly, evidence suggests that the incretin pathway may influence immune cell activation. Consequently, drugs targeting the incretin hormone signaling pathway may ameliorate inflammatory diseases such as inflammatory bowel diseases, cancer, and autoimmune diseases. In this review, we discuss how these hormones may modulate two subsets of CD4 + T cells, the regulatory T cells (Treg)/Th17 axis important for gut homeostasis: thus, preventing the development and progression of inflammatory diseases. We also summarize the main experimental and clinical findings using drugs targeting the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP-1) signaling pathways and their great impact on conditions in which the Treg/Th17 axis is disturbed such as inflammatory diseases and cancer. Understanding the role of incretin stimulation in immune cell activation and function, might contribute to new therapeutic designs for the treatment of inflammatory diseases, autoimmunity, and tumors.

Cyanidin and delphinidin restore colon physiology in high fat diet-fed mice: Involvement of TLR-4 and redox-regulated signaling

Consumption of high fat diets (HFD) mimics a modern or "Western style" diet pattern and can impair intestinal barrier integrity, leading to endotoxemia and associated unhealthy conditions. This study investigated if supplementation with an anthocyanin (cyanidin and delphinidin glucosides)-rich extract (CDRE) could revert or mitigate HFD-induced alterations of colonic physiology in part through the regulation of Toll-Like Receptor 4 (TLR-4)- and redox-regulated signaling. C57BL/6J male mice were fed for 4 weeks with a control or an HFD. Then, mice were divided in four groups fed either control or HFD, or these diets supplemented with CDRE for the subsequent 4 weeks. After 8 weeks on the HFD we observed in the colon: i) disruption of tight junction structure and function; ii) increased TLR-4 expression; iii) increased NADPH oxidase NOX1 expression, and iv) activation of redox-sensitive and TLR-4-triggered pathways, i.e. NF-κB, ERK1/2, JNK1/2, PI3K/Akt. All these events were prevented or reverted by CDRE supplementation. Supporting the relevance of CDRE-mediated downregulation of TLR-4 on its colon beneficial effect; in vitro (Caco-2 cell monolayers), cyanidin, delphinidin and their metabolites protocatechuic and gallic acid, mitigated lipopolysaccharide (LPS)-induced monolayer permeabilization by restoring tight junction structure and dynamics and preventing lipid/protein oxidation. The CDRE also mitigated HFD-mediated alterations in parameters of goblet cell differentiation and function, including the downregulation of markers of goblet cell differentiation (Klf4), and intestinal mucosa healing (Tff3). Results show that a short-term supplementation with cyanidin and delphinidin, protect from HFD-induced alterations in colon physiology in part through the modulation of TLR-4- and redox-regulated signaling.

Clinical significance of mitogen-activated protein kinase kinase kinases in hepatitis B virus -related hepatocellular carcinoma and underlying mechanism exploration

The purpose of this research was to explore the diagnostic/prognostic significance and prospective molecular mechanisms of mitogen-activated protein kinase kinase kinases (MAP3Ks) in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). Diagnostic/prognostic significance of MAP3Ks was screened in the GSE1450 data set and validated in the Guangxi cohort. Various bioinformatics tools were used to explore the biological functions of prognosis-related genes. Subsequently, molecular biology assays were used to verify the biological functions and molecular mechanisms of specific gene. MAP3K9 was observed to be differentially expressed in HCC and adjacent tissues with satisfactory diagnostic value. It was discovered in survival analysis that MAP3K13 and MAP3K15 were associated with overall survival (OS) of patients with HBV-related HCC in the GSE1450 data set and the Guangxi cohort. Nomograms were established based on prognosis-related genes and clinical factors for individualized risk assessment. The assays on HCC cells demonstrated that MAP3K13 regulated the death and proliferation of HCC cells by activating the JNK pathway and inducing the expression of apoptosis-related factors. In conclusion, our results suggested that MAP3K9 might serve as a diagnostic biomarker in HBV-related HCC and MAP3K13 and MAP3K15 might serve as useful prognostic biomarkers. Besides, cytological assays prompted that MAP3K13 might impact the prognosis of HCC by regulating the JNK pathway and inducing apoptosis.

Gut microbiota-derived butyrate regulates gut mucus barrier repair by activating the macrophage/WNT/ERK signaling pathway

Ulcerative colitis (UC) is majorly associated with dysregulation of the dynamic cross-talk among microbial metabolites, intestinal epithelial cells, and macrophages. Several studies have reported the significant role of butyrate in host-microbiota communication. However, whether butyrate provides anti-inflammatory profiles in macrophages, thus contributing to UC intestinal mucus barrier protection, has currently remained elusive. In the current study, we found that butyrate increased mucin production and the proportion of mucin-secreting goblet cells in the colon crypt in a macrophage-dependent manner by using clodronate liposomes. Furthermore, in vivo and in vitro studies were conducted, validating that butyrate facilitates M2 macrophage polarization with the elevated expressions of CD206 and arginase-1 (Arg1). In macrophages/goblet-like LS174T cells co-culture systems, butyrate-primed M2 macrophages significantly enhanced the expression of mucin-2 (MUC2) and SPDEF (goblet cell marker genes) than butyrate alone, while blockade of WNTs secretion or ERK1/2 activation significantly decreased the beneficial effect of butyrate-primed macrophages on goblet cell function. Additionally, the adoptive transfer of butyrate-induced M2 macrophages facilitated the generation of goblet cells and mucus restoration following dextran sulfate sodium (DSS) insult. Taken together, our results revealed a novel mediator of macrophage-goblet cell cross-talk associated with the regulation of epithelial barrier integrity, implying that the microbial metabolite butyrate may serve as a candidate therapeutic target for UC.

Robust differentiation of human enteroendocrine cells from intestinal stem cells

Enteroendocrine (EE) cells are the most abundant hormone-producing cells in humans and are critical regulators of energy homeostasis and gastrointestinal function. Challenges in converting human intestinal stem cells (ISCs) into functional EE cells, ex vivo, have limited progress in elucidating their role in disease pathogenesis and in harnessing their therapeutic potential. To address this, we employed small molecule targeting of the endocannabinoid receptor signaling pathway, JNK, and FOXO1, known to mediate endodermal development and/or hormone production, together with directed differentiation of human ISCs from the duodenum and rectum. We observed marked induction of EE cell differentiation and gut-derived expression and secretion of SST, 5HT, GIP, CCK, GLP-1 and PYY upon treatment with various combinations of three small molecules: rimonabant, SP600125 and AS1842856. Robust differentiation strategies capable of driving human EE cell differentiation is a critical step towards understanding these essential cells and the development of cell-based therapeutics.

Challenges and opportunities targeting mechanisms of epithelial injury and recovery in acute intestinal graft-versus-host disease

Despite advances in immunosuppressive prophylaxis and overall supportive care, gastrointestinal (GI) graft-versus-host disease (GVHD) remains a major, lethal side effect after allogeneic hematopoietic stem cell transplantation (allo-HSCT). It has become increasingly clear that the intestinal epithelium, in addition to being a target of transplant-related toxicity and GVHD, plays an important role in the onset of GVHD. Over the last two decades, increased understanding of the epithelial constituents and their microenvironment has led to the development of novel prophylactic and therapeutic interventions, with the potential to protect the intestinal epithelium from GVHD-associated damage and promote its recovery following insult. In this review, we will discuss intestinal epithelial injury and the role of the intestinal epithelium in GVHD pathogenesis. In addition, we will highlight possible approaches to protect the GI tract from damage posttransplant and to stimulate epithelial regeneration, in order to promote intestinal recovery. Combined treatment modalities integrating immunomodulation, epithelial protection, and induction of regeneration may hold the key to unlocking mucosal recovery and optimizing therapy for acute intestinal GVHD.

The lipid peroxidation product EKODE exacerbates colonic inflammation and colon tumorigenesis

Oxidative stress is emerging as an important contributor to the pathogenesis of colorectal cancer (CRC), however, the molecular mechanisms by which the disturbed redox balance regulates CRC development remain undefined. Using a liquid chromatography–tandem mass spectrometry-based lipidomics, we found that epoxyketooctadecenoic acid (EKODE), which is a lipid peroxidation product, was among the most dramatically increased lipid molecules in the colon of azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC mice. This is, at least in part, due to increased oxidative stress in colon tumors, as assessed by analyzing gene expression of oxidative markers in AOM/DSS-induced CRC mice and human CRC patients in the Cancer Genome Atlas (TCGA) database. Systemic, short-time treatment with low-dose EKODE increased the severity of DSS-induced colitis, caused intestinal barrier dysfunction and enhanced lipopolysaccharide (LPS)/bacterial translocation, and exacerbates the development of AOM/DSS-induced CRC in mice. Furthermore, treatment with EKODE, at nM doses, induced inflammatory responses via JNK-dependent mechanisms in both colon cancer cells and macrophage cells. Overall, these results demonstrate that the lipid peroxidation product EKODE is an important mediator of colonic inflammation and colon tumorigenesis, providing a novel mechanistic linkage between oxidative stress and CRC development.

Isoform-specific functions of c-Jun N-terminal kinase 1 and 2 in lung ischemia-reperfusion injury through the c-Jun/activator protein-1 pathway

BACKGROUND

c-Jun N-terminal kinase 1 (JNK1) and JNK2 regulate distinct pathological processes in lung diseases. Here we discriminated the respective roles of these kinases in lung transplantation-induced ischemia-reperfusion injury (IRI).

METHODS

Rat pulmonary microvascular endothelial cells were transfected with JNK1 small-interfering RNA (siRNA) and JNK2 siRNA and then subjected to in vitro IRI. For the isoform confirmed to aggravate IRI, the delivery of short-hairpin RNA (shRNA) plasmid was performed by intratracheal administration 48 hours before transplantation into donor rats. After a 3-hour reperfusion, the samples were collected.

RESULTS

JNK1 siRNA decreased but JNK2 siRNA increased JNK phosphorylation and activity, phosphorylated and total c-Jun, and activator protein-1 activity. Although JNK1 siRNA decreased apoptosis and the levels of malondialdehyde, interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF-α), it increased the levels of superoxide dismutase, S-phase percentage, and cyclin D1; JNK2 siRNA had a converse effect. JNK1 siRNA decreased the level of lactate dehydrogenase and increased the levels of VE-cadherin, nitric oxide, phosphorylated nitric oxide synthase, and cell viability; JNK2 si RNA had a converse effect. Compared with the control group, the JNK1 shRNA group exhibited a higher lung oxygenation index and lower lung apoptosis index, injury score, wet weight:dry weight ratio, and levels of IL-1, IL-6, and TNF-α.

CONCLUSIONS

JNK1 aggravated, but JNK2 alleviated, IRI through differential regulation of the JNK1 pathway in in vitro ischemia-reperfusion. JNK1 silence attenuated lung graft dysfunction by inhibiting inflammation and apoptosis. These findings provide a theoretical basis for devising therapeutic strategies against IRI after lung transplantation.

Mechanisms underlying reduced weight gain in intestinal fatty acid-binding protein (IFABP) null mice

Intestinal-fatty acid binding protein (IFABP; FABP2) is a 15-kDa intracellular protein abundantly present in the cytosol of the small intestinal (SI) enterocyte. High-fat (HF) feeding of IFABP-/- mice resulted in reduced weight gain and fat mass relative to wild-type (WT) mice. Here, we examined intestinal properties that may underlie the observed lean phenotype of high fat-fed IFABP-/- mice. No alterations in fecal lipid content were found, suggesting that the IFABP-/- mice are not malabsorbing dietary fat. However, the total excreted fecal mass, normalized to food intake, was increased for the IFABP-/- mice relative to WT mice. Moreover, intestinal transit time was more rapid in the IFABP-/- mice. IFABP-/- mice displayed a shortened average villus length, a thinner muscularis layer, reduced goblet cell density, and reduced Paneth cell abundance. The number of proliferating cells in the crypts of IFABP-/- mice did not differ from that of WT mice, suggesting that the blunt villi phenotype is not due to alterations in proliferation. IFABP-/- mice were observed to have altered expression of genes and proteins related to intestinal structure, while immunohistochemical analyses revealed increased staining for markers of inflammation. Taken together, these studies indicate that the ablation of IFABP, coupled with high-fat feeding, leads to changes in gut motility and morphology, which likely contribute to the relatively leaner phenotype occurring at the whole-body level. Thus, IFABP is likely involved in dietary lipid sensing and signaling, influencing intestinal motility, intestinal structure, and nutrient absorption, thereby impacting systemic energy metabolism.NEW & NOTEWORTHY Intestinal fatty acid binding protein (IFABP) is thought to be essential for the efficient uptake and trafficking of dietary fatty acids. In this study, we demonstrate that high-fat-fed IFABP-/- mice have an increased fecal output and are likely malabsorbing other nutrients in addition to lipid. Furthermore, we observe that the ablation of IFABP leads to marked alterations in intestinal morphology and secretory cell abundance.

ATF2 and ATF7 Are Critical Mediators of Intestinal Epithelial Repair

BACKGROUND & AIMS

Activation factor-1 transcription factor family members activating transcription factors 2 and 7 (ATF2 and ATF7) have highly redundant functions owing to highly homologous DNA binding sites. Their role in intestinal epithelial homeostasis and repair is unknown. Here, we assessed the role of these proteins in these conditions in an intestine-specific mouse model.

METHODS

We performed in vivo and ex vivo experiments using Villin-CreERT2Atf2fl/flAtf7ko/ko mice. We investigated the effects of intestinal epithelium-specific deletion of the Atf2 DNA binding region in Atf7-/- mice on cellular proliferation, differentiation, apoptosis, and epithelial barrier function under homeostatic conditions. Subsequently, we exposed mice to 2% dextran sulfate sodium (DSS) for 7 days and 12 Gy whole-body irradiation and assessed the response to epithelial damage.

RESULTS

Activating phosphorylation of ATF2 and ATF7 was detected mainly in the crypts of the small intestine and the lower crypt region of the colonic epithelium. Under homeostatic conditions, no major phenotypic changes were detectable in the intestine of ATF mutant mice. However, on DSS exposure or whole-body irradiation, the intestinal epithelium showed a clearly impaired regenerative response. Mutant mice developed severe ulceration and inflammation associated with increased epithelial apoptosis on DSS exposure and were less able to regenerate colonic crypts on irradiation. In vitro, organoids derived from double-mutant epithelium had a growth disadvantage compared with wild-type organoids, impaired wound healing capacity in scratch assay, and increased sensitivity to tumor necrosis factor-α-induced damage.

CONCLUSIONS

ATF2 and ATF7 are dispensable for epithelial homeostasis, but are required to maintain epithelial regenerative capacity and protect against cell death during intestinal epithelial damage and repair.

Alpinetin improves intestinal barrier homeostasis via regulating AhR/suv39h1/TSC2/mTORC1/autophagy pathway

The injury of intestinal epithelial barrier is considered as the key pathophysiological process in response to gastrointestinal infection and inflammation, and plays an important role in the initiation and development of colitis. Alpinetin has been shown to improve intestinal barrier homeostasis under colitis condition, but the mechanism is still unclear. Here, we showed that alpinetin significantly improved transepithelial electrical resistance (TEER) in TNF-α-stimulated Caco-2 cells, which was mainly mediated by inhibiting the apoptosis. Mechanistic studies demonstrated that alpinetin markedly increased the production of autophagosomes, along with obvious regulation of LC3B-II, beclin-1, p62, Atg7 and Atg5 expressions. In addition, it also markedly repressed the activation of mTORC1 signaling pathway, which was ascribed to TSC2 rather than p-AKT, p-ERK, p-AMPKα or PTEN expressions in Caco-2 and NCM460 cells. Furthermore, the enrichment of H3K9me3 at TSC2 promoter region was decreased and ubiquitin proteasome degradation of suv39h1 was increased. Additionally, alpinetin activated aryl hydrocarbon receptor (AhR) and promoted co-localization of AhR with suv39h1 in the cytoplasm. The relationship between alpinetin-regulated AhR/suv39h1/TSC2/mTORC1 signals, autophagy and apoptosis of Caco-2 and NCM460 cells was confirmed by using CH223191, siAhR, siTSC2 and chloroquine. Finally, CH223191 and leucine abolished alpinetin-mediated inhibition of intestinal epithelial cells apoptosis, improvement of intestinal epithelial barrier and amelioration of colitis.

Aryl hydrocarbon receptor activation alleviates dextran sodium sulfate-induced colitis through enhancing the differentiation of goblet cells

BACKGROUND

The intestinal inflammation induces disruption of the intestinal barrier function and leads to bacteria invasion. Accumulating evidences revealed that the aryl hydrocarbon receptor (AhR) plays a vital role in maintaining the intestinal barrier function. However, the precise mechanism remains to be unclear.

METHODS

Adult C57BL/6J mice were randomly divided into three groups: Sham, DSS and DSS + 6-formylindolo (3, 2-b) carbazole (FICZ)group. The colons and epithelial cell were harvested for histological examination, pro-inflammatory cytokines detection, bacterial load analysis, immunohistochemistry and Muc2 protein analysis. Under physiological condition, AhRKO model and FICZ treatment were used to evaluate the roles of AhR in the differentiation of goblet cells and the expression of Muc2 in mice. In vitro, we used HT29 mol to research the signaling pathway.

RESULTS

AhR activation by FICZ could increase the Muc2 expression and the number of goblet cells and reduce bacterial infiltration to ameliorate DSS-induced Colitis. Under physiological conditions, the treatment of FICZ promote the differentiation of goblet cell and the expression of Muc2 and inhibit the notch-signaling. Genetic deletion of AhR led to the loss of goblet cells and the decrease of Muc2 expression and enhance the notch-signaling. In HT29 cells, the differentiation of goblet cell meditated by AhR can be abolished by the inhibitor of AhR, pErk1/2 and knocking-down AhR.

CONCLUSION

FICZ promoted the differentiation of goblet cell through AhR-pErk1/2 signaling pathway and ameliorate DSS-induced Colitis.

SCF/c-KIT Signaling Increased Mucin2 Production by Maintaining Atoh1 Expression in Mucinous Colorectal Adenocarcinoma

Mucinous colorectal adenocarcinoma (MCA) patients often a show high risk of malignant potential and a poorer survival rate. Given that the pathological feature and oncobiological characteristics of MCA are correlated with its abundant extracellular mucin2 (MUC2), we paid interest toward investigating the key factor that promotes MUC2 production exposure to highly-activated stem cell factor (SCF)/c-KIT signaling, which we believed to contribute to MCA formation. Long-term azoxymethane and dextran sodium sulfate treatment successfully induced MCA only in wild-type (WT) mice at week 37 and 43, while all c-kit loss-of-function mutant mice (Wads^m/m) developed non-MCA. Significantly, MUC2 and its key transcriptional factor Atonal homologue 1 (Atoh1) were remarkably expressed in MCA mice compared with non-MCA mice. Atoh1 was significantly elevated in colorectal cancer (CRC) cells stimulated by exogenous SCF or overexpressing c-KIT in vitro, while decreased by the blockage of SCF/c-KIT signaling with Imatinib. Furthermore, the maintained Atoh1 protein level was due to the inactive glycogen synthase kinase 3β (p-GSK3β) by virtue of the activated SCF/c-KIT-Protein Kinase B (AKT) signaling. Similar results were obtained from the ONCOMINE database and CRC patients. In conclusion, we suggested that SCF/c-KIT signaling promoted MUC2 production and MCA tumorigenesis by maintaining Atoh1 expression. Therefore, targeting the related key molecules might be beneficial for treating MCA patients.

Combination of arsenic trioxide and Dasatinib: a new strategy to treat Philadelphia chromosome-positive acute lymphoblastic leukaemia

Tyrosine kinase inhibitors (TKIs) have significantly improved the prognosis of Philadelphia chromosome-positive acute lymphoblastic leukaemia (Ph⁺ ALL), one of the most common and aggressive forms of haematological malignancies. However, TKI resistance has remained an unsolved issue. In this study, we investigate the impact of adding arsenic trioxide (ATO) on the action of Dasatinib, a second-generation TKI, in Ph⁺ ALL. We show that ATO cooperates with Dasatinib in both TKI-sensitive and resistant Ph⁺ ALL cell lines to increase apoptosis and we unravel the underlying mechanisms. Indeed, combining ATO and Dasatinib leads to severe cell apoptosis by activating the UPR apoptotic IRE1/JNK/PUMA axis, while neutralizing the UPR ATF4-dependent anti-apoptotic axis, activated by ATO alone. Additionally, ATO and Dasatinib in combination repress the expression of several genes, which we previously showed to be associated with shorter survival probability in ALL patients. Overall these data support the use of ATO in combination with Dasatinib as a novel therapeutic regimen for Ph⁺ ALL patients.