Apoptosis in the intestinal epithelium: its relevance in normal and pathophysiological conditions

Nutritional strategies to reduce intestinal cell apoptosis by alleviating oxidative stress

The gut barrier is the first line of defense against harmful substances and pathogens in the intestinal tract. The balance of proliferation and apoptosis of intestinal epithelial cells (IECs) is crucial for maintaining the integrity of the intestinal mucosa and its function. However, oxidative stress and inflammation can cause DNA damage and abnormal apoptosis of the IECs, leading to the disruption of the intestinal epithelial barrier. This, in turn, can directly or indirectly cause various acute and chronic intestinal diseases. In recent years, there has been a growing understanding of the vital role of dietary ingredients in gut health. Studies have shown that certain amino acids, fibers, vitamins, and polyphenols in the diet can protect IECs from excessive apoptosis caused by oxidative stress, and limit intestinal inflammation. This review aims to describe the molecular mechanism of apoptosis and its relationship with intestinal function, and to discuss the modulation of IECs' physiological function, the intestinal epithelial barrier, and gut health by various nutrients. The findings of this review may provide a theoretical basis for the use of nutritional interventions in clinical intestinal disease research and animal production, ultimately leading to improved human and animal intestinal health.

Modelling the effect of cell motility on mixing and invasion in epithelial monolayers

Collective cell invasion underlies several biological processes such as wound healing, embryonic development, and cancerous invasion. Here, we investigate the impact of cell motility on invasion in epithelial monolayers and its coupling to cellular mechanical properties, such as cell-cell adhesion and cortex contractility. We develop a two-dimensional computational model for cells with active motility based on the cellular Potts model, which predicts that the cellular invasion speed is mainly determined by active cell motility and is independent of the biological and mechanical properties of the cells. We also find that, in general, motile cells out-compete and invade non-motile cells, however, this can be reversed by differential cell proliferation. Stable coexistence of motile and static cell types is also possible for certain parameter regimes.

Unraveling Crucial Mitochondria-Related Genes in the Transition from Ulcerative Colitis to Colorectal Cancer

Purpose

To clarify the significance of mitochondria-related differentially expressed genes (MTDEGs) in UC carcinogenesis through a bioinformatics analysis and provide potential therapeutic targets for patients with UC associated colorectal cancer.

Methods

Microarray GSE37283 was utilized to investigate differentially expressed genes (DEGs) in UC and UC with neoplasia (UCN). MTDEGs were identified by intersecting DEGs with human mitochondrial genes. Utilizing LASSO and random forest analyses, we identified three crucial genes. Subsequently, using ROC curve to investigate the predictive ability of three key genes. Following, three key genes were confirmed in AOM/DSS mice model by Real-time PCR. Finally, single-sample gene set enrichment analysis (ssGSEA) was employed to explore the correlation between the hub genes and immune cells infiltration in UC carcinogenesis.

Results

The three identified hub MTDEGs (HMGCS2, MAVS, RDH13) may exhibit significant diagnostic specificity in the transition from UC to UCN. Real-time PCR assay further confirmed that the expressions of HMGCS2 and RDH13 were significantly downregulated in UCN mice than that in UC mice. ssGSEA analysis revealed the hub genes were highly associated with CD56dim natural killer cells.

Conclusion

RDH13, HMGCS2, and MAVS may become diagnostic indicators and potential biomarkers for UCN. Our research has the potential to enhance our understanding of the mechanisms underlying carcinogenesis in UC.

T-bet Regulates Ion Channels and Transporters and Induces Apoptosis in Intestinal Epithelial Cells

T-bet, encoded by TBX21, is extensively expressed across various immune cell types, and orchestrates critical functions in their development, survival, and physiological activities. However, the role of T-bet in non-immune compartments, notably the epithelial cells, remains obscure. Herein, a Tet-O-T-bet transgenic mouse strain is generated for doxycycline-inducible T-bet expression in adult animals. Unexpectedly, ubiquitous T-bet overexpression causes acute diarrhea, intestinal damage, and rapid mortality. Cell-type-specific analyses reveal that T-bet-driven pathology is not attributable to its overexpression in CD4+ T cells or myeloid lineages. Instead, inducible T-bet overexpression in the intestinal epithelial cells is the critical determinant of the observed lethal phenotype. Mechanistically, T-bet overexpression modulates ion channel and transporter profiles in gut epithelial cells, triggering profound fluid secretion and subsequent lethal dehydration. Furthermore, ectopic T-bet expression enhances gut epithelial cell apoptosis and markedly suppresses colon cancer development in xenograft models. Collectively, the findings unveil a previously unrecognized role of T-bet in intestinal epithelial cells for inducing apoptosis, diarrhea, and local inflammation, thus implicating its potential as a therapeutic target for the treatment of cancer and inflammatory diseases.

Sesame cake extract attenuates dextran sulfate sodium-induced colitis through inhibition of oxidative stress in mice

Inflammatory bowel disease (IBD) is a chronic inflammatory disease occurring in the gut causing chronic diarrhea and abdominal pain with severe complications. Sesame cake is a by-product of sesame oil production, possessing various beneficial properties; however, little is known about the effect of sesame cake extract (SCE) against IBD. The aim of this study was to investigate the protective effect of SCE against dextran sulfate sodium (DSS)-induced colitis in mice. Administration of SCE was first performed at 7 days before treating mice with 2.5% DSS to induce colitis for 7 days. SCE pretreatment improved symptoms of DSS-induced colitis. In addition, SCE ameliorated histopathological damages of the mucus layer in colon tissues and decreased pro-inflammatory cytokines in colitis-induced mice. SCE also suppressed apoptosis and oxidative stress in colitis-induced colon tissues. Together, these findings suggest that SCE could be potential nutraceuticals for treating colitis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01367-1.

Inhibition of TLR4, NF-κB, and INOS pathways mediates ameliorative effect of syringic acid in experimental ulcerative colitis in rats

OBJECTIVE

Numerous therapeutics and pharmacological properties have been reported in syringic acid (SA). In this study, we aimed to evaluate effect of SA in ulcerative colitis (UC) in rats considering effect on TLR4, NF-κB, and INOS pathways.

MATERIALS AND METHODS

48 Wistar rats were randomly designated into six groups (n = 8). UC was induced via intra-rectal administration of 7% acetic acid (0.8 ml). SA at doses of 10, 25, 50 mg/kg was administrated through gavage, and dexamethasone (2 mg/kg) administrated intra-peritoneally for 5 consecutive days. The macroscopic and histopathological damages as well as expression of inflammatory and apoptotic genes along with superoxide dismutase (SOD) and catalase (CAT) activities, total antioxidant capacity (TAC), nitric oxide (NO), and malondialdehyde (MDA) levels in the colon tissue were assessed.

RESULTS

UC led to an increase in the apoptotic and inflammatory genes, NO and MDA levels as well as decrease in TAC level, and SOD and CAT activities (p < 0.05). UC also caused severe damage, edema, inflammation, and necrosis in the colon. SA significantly reduced gene expressions of INOS, TLR4, IL-6, IL-1β, NF-κB, Caspase-3, Caspase-8, and Bax. SA ameliorated negative macroscopic and histopathologic effects of UC. SA significantly reduced MDA and NO levels, and increased TAC level and CAT activity in the colon tissue in comparison to the UC rats without treatment (p < 0.05).

CONCLUSION

SA via attenuation of the TLR4-NF-κB, NF-κB-INOS-NO pathways, oxidative stress, inflammation, and apoptosis of UC in rats.

Unraveling the gut-Lung axis: Exploring complex mechanisms in disease interplay

The link between gut and lung starts as early as during organogenesis. Even though they are anatomically distinct, essential bidirectional crosstalk via complex mechanisms supports GLA. Emerging studies have demonstrated the association of gut and lung diseases via multifaceted mechanisms. Advancements in omics and metagenomics technologies revealed a potential link between gut and lung microbiota, adding further complexity to GLA. Despite substantial studies on GLA in various disease models, mechanisms beyond microbial dysbiosis regulating the interplay between gut and lung tissues during disease conditions are not thoroughly reviewed. This review outlines disease specific GLA mechanisms, emphasizing research gaps with a focus on gut-to-lung direction based on current GLA literature. Moreover, the review discusses potential gut microbiota and their products like metabolites, immune modulators, and non-bacterial contributions as a basis for developing treatment strategies for lung diseases. Advanced experimental methods, modern diagnostic tools, and technological advancements are also highlighted as crucial areas for improvement in developing novel therapeutic approaches for GLA-related diseases. In conclusion, this review underscores the importance of exploring additional mechanisms within the GLA to gain a deeper understanding that could aid in preventing and treating a wide spectrum of lung diseases.

Quinic acid ameliorates ulcerative colitis in rats, through the inhibition of two TLR4-NF-κB and NF-κB-INOS-NO signaling pathways

OBJECTIVE

In this study, the therapeutic effect of quinic acid (QA), which has anti-inflammatory activity, was investigated on acetic acid-induced colitis in male Wistar rats.

METHODS

Ulcerative colitis (UC) was induced in rats by acetic acid intrarectally, and the protective effects of QA in 10, 30, 60, and 100 mg/kg doses were investigated. Rats were treated for 5 days and their colon tissues were dissected out at the end. Macroscopic and histopathological examinations were performed in colon tissues. Also, the expression of inflammatory and apoptotic genes, including TLR4, IL-1β, INOS, IL-6, TNF-α, NF-κB, Caspase-3, Caspase-8, Bax, and Bcl-2, was measured. Biochemistry indices, such as malondialdehyde (MDA) and nitrite oxide (NO) content, in addition to, total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), and enzymes activities were also assessed.

RESULTS

Colitis increased the levels of MDA and NO, and enhanced the inflammatory and apoptotic gene expressions, while reducing the SOD and CAT enzymes activity, and TAC levels in the colitis rats. Also, results showed that colitis was associated with the infiltration of inflammatory cells, epithelium damage, and edema in colon tissue. QA significantly ameliorated histopathological indices, oxidative stress, inflammation, and apoptosis in colitis rats.

CONCLUSION

QA ameliorated UC through the inhibition of two TLR4-NF-κB and NF-κB-INOS-NO signaling pathways, which results in the reduction of colitis complications, including oxidative stress, inflammation, apoptosis and histopathological injuries in rats. Therefore it can be concluded, that QA exerts its therapeutic effects through antiapoptotic, antioxidant, and anti-inflammatory properties.

Autophagy attenuates placental apoptosis, oxidative stress and fetal growth restriction in pregnant ewes

Bisphenol A (BPA)-induced oxidative stress (OS) and its potentially associated autophagy and apoptosis have not been studied previously in pregnant ewes. Accordingly, this study investigated the underlying mechanisms of BPA-induced autophagy and apoptosis in the placenta and primary trophoblasts of pregnant ewes exposed to BPA both in vivo and in vitro. In vivo experiment, pregnant Hu ewes (n = 8) were exposed to 5 mg/kg/d of BPA compared to control ewes (n = 8) receiving only corn oil from day 40 through day 110 of gestation. Exposure to BPA during gestation resulted in placental insufficiency, fetal growth restriction (FGR), autophagy, endoplasmic reticulum stress (ERS), mitochondrial dysfunction, OS, and apoptosis in type A placentomes. Regarding in vitro model, primary ovine trophoblasts were exposed to BPA, BPA plus chloroquine (CQ; an autophagy inhibitor) or BPA plus rapamycin (RAP; an autophagy activator) for 12 h. Data illustrated that exposure to BPA enhanced autophagy (ULK1, Beclin-1, LC3, Parkin, and PINK1), ERS (GRP78, CHOP10, ATF4, and ATF6) and apoptosis (Caspase 3, Bcl-2, Bax, P53) but decreased the antioxidant (CAT, Nrf2, HO-1, and NQO1)-related mRNA and protein expressions as well as impaired the mitochondrial function. Moreover, treatment with CQ exacerbated the BPA-mediated OS, mitochondrial dysfunction, apoptosis, and ERS. On the contrary, RAP treatment counteracted the BPA-induced trophoblast dysfunctions mentioned above. Overall, the findings illustrated that BPA exposure could contribute to autophagy in the ovine placenta and trophoblasts and that autophagy, in turn, could alleviate BPA-induced apoptosis, mitochondrial dysfunction, ERS, and OS. These results offer new mechanistic insights into the role of autophagy in mitigating BPA-induced placental dysfunctions and FGR.

A novel oral formulation of the melanocortin-1 receptor agonist PL8177 resolves inflammation in preclinical studies of inflammatory bowel disease and is gut restricted in rats, dogs, and humans

Introduction

PL8177 is a potent and selective agonist of the melanocortin 1 receptor (MC1R). PL8177 has shown efficacy in reversing intestinal inflammation in a cannulated rat ulcerative colitis model. To facilitate oral delivery, a novel, polymer-encapsulated formulation of PL8177 was developed. This formulation was tested in 2 rat ulcerative colitis models and evaluated for distribution, in vivo, in rats, dogs, and humans.

Methods

The rat models of colitis were induced by treatment with 2,4-dinitrobenzenesulfonic acid or dextran sulfate sodium. Single nuclei RNA sequencing of colon tissues was performed to characterize the mechanism of action. The distribution and concentration of PL8177 and the main metabolite within the GI tract after a single oral dose of PL8177 was investigated in rats and dogs. A phase 0 clinical study using a single microdose (70 µg) of [14C]-labeled PL8177 investigated the release of PL8177 in the colon of healthy men after oral administration.

Results

Rats treated with 50 µg oral PL8177 demonstrated significantly lower macroscopic colon damage scores and improvement in colon weight, stool consistency, and fecal occult blood vs the vehicle without active drug. Histopathology analysis resulted in the maintenance of intact colon structure and barrier, reduced immune cell infiltration, and increased enterocytes with PL8177 treatment. Transcriptome data show that oral PL8177 50 µg treatment causes relative cell populations and key gene expressions levels to move closer to healthy controls. Compared with vehicle, treated colon samples show negative enrichment of immune marker genes and diverse immune-related pathways. In rats and dogs, orally administered PL8177 was detected at higher amounts in the colon vs upper GI tract. [14C]-PL8177 and the main metabolite were detected in the feces but not in the plasma and urine in humans. This suggests that the parent drug [14C]-PL8177 was released from the polymer formulation and metabolized within the GI tract, where it would be expected to exert its effect.

Conclusion

Collectively, these findings support further research into the oral formulation of PL8177 as a possible therapeutic for GI inflammatory diseases in humans.

Modelling of Tissue Invasion in Epithelial Monolayers

Mathematical and computational models are used to describe biomechanical processes in multicellular systems. Here, we develop a model to analyse how two types of epithelial cell layers interact during tissue invasion depending on their cellular properties, i.e., simulating cancer cells expanding into a region of normal cells. We model the tissue invasion process using the cellular Potts model and implement our two-dimensional computational simulations in the software package CompuCell3D. The model predicts that differences in mechanical properties of cells can lead to tissue invasion, even if the division rates and death rates of the two cell types are the same. We also show how the invasion speed varies depending on the cell division and death rates and the mechanical properties of the cells.

Lipopolysaccharide promotes apoptosis and oxidative injury of porcine small intestinal epithelial cells by down-regulating the expression of glutamine transporter ASCT2

The present study aimed to investigate the effects of lipopolysaccharide (LPS) stimulation on oxidative damage, apoptosis, and glutamine (Gln) transporter Alanine-Serine-Cysteine transporter 2 (ASCT2) expression in porcine small intestinal epithelial cells (IPEC-J2), and preliminarily elucidated the relationship between ASCT2 expression level and oxidative damage and apoptosis of IPEC-J2 cells. IPEC-J2 cells were treated without (control group, CON, N = 6) or with 1 μg/mL LPS (LPS group, LPS, N = 6). Cell viability, lactate dehydrogenase (LDH) content, malonaldehyde (MDA), anti-oxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px], and total anti-oxidant capacity [T-AOC]), apoptosis of IPEC-J2 cells, the expression of Caspase3, the expression of ASCT2 mRNA and ASCT2 protein was detected. The results showed that LPS stimulation of IPEC-J2 cells significantly reduced the cell viability, and anti-oxidant enzymes activity (SOD, CAT, and GSH-Px), and significantly increased LDH and MDA release. Flow cytometry results showed that LPS stimulation significantly increased the late apoptosis rate and the total apoptosis rate of IPEC-J2 cells. The immunofluorescence results showed that the fluorescence intensity of LPS stimulated IPEC-J2 cells was significantly enhanced. LPS stimulation significantly decreased the mRNA and protein expression of ASCT2 in IPEC-J2 cells. The correlation analysis showed that ASCT2 expression was negatively correlated with apoptosis, and positively correlated with the anti-oxidant capacity of IPEC-J2 cells. According to the results of this study, it can be preliminarily concluded that LPS promotes the apoptosis and oxidative injury of IPEC-J2 cells by down-regulating the expression of ASCT2.

Coumaric acid ameliorates experimental colitis in rats through attenuation of oxidative stress, inflammatory response and apoptosis

OBJECTIVE

Due to the high side effects of commonly used drugs and according to the pharmacological properties reported for coumaric acid (CA), this study was designed to determine the impact of CA on acetic acid-induced colitis in rats, considering its possible anti-inflammatory, antioxidant, and anti-apoptotic properties.

MATERIALS AND METHODS

Forty-eight male Wistar rats were divided into 6 equal groups (n = 8). Colitis was induced by acetic acid intrarectally. CA in three different doses (50, 100, and 150 mg/kg) was administrated for 5 days. Finally, the macroscopic and histopathological changes in the colon tissue were examined. The expression of inflammatory and apoptotic genes, including NF-κB, TNF-α, INOS, IL-1β, IL-6, TLR4, Caspase-3, Caspase-8, Bax, Bcl-2 was assessed. In addition, changes in the levels of catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), nitrite, and total antioxidant capacity (TAC) were measured in the colon tissue.

RESULTS

Colitis led to a decrease in TAC and the activity levels of CAT and SOD and an increase in the expression of inflammatory and apoptotic genes, MDA, and nitrite levels in the colon. Colitis was also associated with edema and severe damage to the epithelium, infiltration of inflammatory cells, and the presence of ulcers and necrosis in the colon tissue. CA significantly improved the inflammation, oxidative stress, apoptosis, and histopathological indices caused by acetic acid-induced colitis on the colon.

CONCLUSION

It is concluded that CA probably exerts its positive effects in the management of colitis, through its anti-inflammatory, antioxidant, and anti-apoptotic properties.

Inflammatory cytokines directly disrupt the bovine intestinal epithelial barrier

The small intestinal mucosa constitutes a physical barrier separating the gut lumen from sterile internal tissues. Junctional complexes between cells regulate transport across the barrier, preventing water loss and the entry of noxious molecules or pathogens. Inflammatory diseases in cattle disrupt this barrier; nonetheless, mechanisms of barrier disruption in cattle are poorly understood. We investigated the direct effects of three inflammatory cytokines, TNFα, IFNγ, and IL-18, on the bovine intestinal barrier utilizing intestinal organoids. Flux of fluorescein isothiocyanate (FITC)-labeled dextran was used to investigate barrier permeability. Immunocytochemistry and transmission electron microscopy were used to investigate junctional morphology, specifically tortuosity and length/width, respectively. Immunocytochemistry and flow cytometry was used to investigate cellular turnover via proliferation and apoptosis. Our study shows that 24-h cytokine treatment with TNFα or IFNγ significantly increased dextran permeability and tight junctional tortuosity, and reduced cellular proliferation. TNFα reduced the percentage of G2/M phase cells, and IFNγ treatment increased cell apoptotic rate. IL-18 did not directly induce significant changes to barrier permeability or cellular turnover. Our study concludes that the inflammatory cytokines, TNFα and IFNγ, directly induce intestinal epithelial barrier dysfunction and alter the tight junctional morphology and rate of cellular turnover in bovine intestinal epithelial cells.

The Protective Effect of Ginsenoside Rg1 on Apoptosis in Human Ankle Joint Traumatic Arthritis Chondrocytes

The ankle biomechanics is easily changed due to the acute injury of the tissue around the ankle joint and the damage of the ankle joint structure, such as ankle instability and joint surface imbalance. When the mechanical load of the ankle changes, it can cause ankle regeneration and remodeling processes such as cartilage loss, bone remodeling, and degenerative changes. The aim of this study was to investigate the effect and mechanism of ginsenoside Rg1 against interleukin-1β (IL-1β)-induced apoptosis in human articular chondrocytes (HACs). The apoptosis model of HAC cells was established by IL-1β induction, and then the HAC cells were cultured with different concentrations of Rg1. The protective effect of Rg1 on HAC cell apoptosis was investigated by detecting the changes of apoptosis and activity of PI3K/Akt/mitochondrial signaling pathway. The results showed that a specific concentration of Rg1 could promote the proliferation of IL-1β-induced HAC cells and inhibit apoptosis. At the same time, Rg1 treatment with specific concentration can reduce the content of reactive oxygen species (ROS) and malondialdehyde (MDA) in HACs and improve the related expression of mitochondrial membrane potential (MMP). Furthermore, qRT-PCR and western blot results showed that Rg1 could improve the low expression of Bcl-2 and inhibit the high expression of Bax, caspase-3, caspase-8, caspase-9, FasL, AIF, and Cyto c in IL-1β-induced cells. In summary, Rg1 can inhibit IL-1β-induced apoptosis of HAC cells by decreasing the activity of PI3K/Akt/mitochondrial signaling pathway, and Rg1 has a protective effect on apoptosis of HAC cells.

Cyclic GMP-AMP synthase contributes to epithelial homeostasis in intestinal inflammation via Beclin-1-mediated autophagy

Inflammatory bowel disease (IBD) represents a set of idiopathic and chronic inflammatory diseases of the gastrointestinal tract. Central to the pathogenesis of IBD is a dysregulation of normal intestinal epithelial homeostasis. cGAS is a DNA-sensing receptor demonstrated to promote autophagy, a mechanism that removes dysfunctional cellular components. Beclin-1 is a crucial protein involved in the initiation of autophagy. We hypothesized that cGAS plays a key role in intestinal homeostasis by upregulating Beclin-1-mediated autophagy. We evaluated intestinal cGAS levels in humans with IBD and in murine colonic tissue after performing a 2% dextran sulfate sodium (DSS) colitis model. Autophagy and cell death mechanisms were studied in cGAS KO and WT mice via qPCR, WB analysis, H&E, IF, and TUNEL staining. Autophagy was measured in stimulated intestinal epithelial cells (IECs) via WB analysis. Our data demonstrates cGAS to be upregulated during human and murine colitis. Furthermore, cGAS deficiency leads to worsened colitis and decreased levels of autophagy proteins including Beclin-1 and LC3-II. Co-IP demonstrates a direct binding between cGAS and Beclin-1 in IECs. Transfection of cGAS in stimulated HCT-116 cells leads to increased autophagy. IECs isolated from cGAS KO have diminished autophagic flux. cGAS KO mice subjected to DSS have increased cell death and cleaved caspase-3. Lastly, treatment of cGAS KO mice with rapamycin decreased the severity of colitis. Our data suggest that cGAS maintains intestinal epithelial homeostasis during human IBD and murine colitis by upregulating Beclin-1-mediated autophagy and preventing IEC death. Rescue of autophagy can attenuate the severity of colitis associated with cGAS deficiency.

Prevention and management of human cytomegalovirus in pediatric HSCT recipients: A review

Cytomegalovirus (CMV), like other herpesviruses, has the unique ability to establish latent infection with subsequent reactivation during periods of stress and immunosuppression. Herpesviruses cause potentially devastating disease, particularly in hematopoietic stem cell transplant (HSCT) recipients. CMV is especially of concern in HSCT recipients given the high community seroprevalence, high risk of reactivation and high risk of transmission from HSCT donors to recipients causing primary infection after transplantation. The risk of CMV infection and severity of CMV disease varies depending on the underlying disease of the HSCT recipient, donor and recipient CMV status prior to HSCT, type of conditioning therapy in preparation for HSCT, allogeneic versus autologous HSCT, donor graft source, timing of infection in relation to HSCT, and other patient comorbidities. Different strategies exist for prevention (e.g., preemptive therapy vs. universal prophylaxis) as well as management of CMV disease (e.g., antiviral therapy, augmenting immune reconstitution, cytotoxic T-cell therapy). The purpose of this narrative review is to discuss diagnosis, prevention, and management of CMV infection and disease at different stages of HSCT, including key points illustrated through presentations of complex cases and difficult clinical scenarios. Traditional and novel strategies for CMV management will be discussed in the context of these unique clinical cases.

Inhibition of Prolyl Oligopeptidase Prevents Consequences of Reperfusion following Intestinal Ischemia

BACKGROUND

Intestinal ischemia/reperfusion injury (IRI) remains a clinical event that contributes to high morbidity and mortality rates. Intestinal epithelium is exposed to histological and vascular changes following tissue ischemia. Prolyl endopeptidase (PREP), involved in inflammatory responses, could be targeted for recovery from the permanent consequences following intestinal ischemia. Our aim was to investigate the role of PREP inhibitor KYP-2047 in tissue damage, angiogenesis, and endothelial barrier permeability after intestinal IRI in mice.

METHODS

KYP-2047 treatments were performed 5 min prior to intestinal damage. Intestinal IRI was induced in mice by clamping the superior mesenteric artery and the celiac trunk for 30 min, followed by 1 h of reperfusion.

RESULTS

PREP inhibition by KYP-2047 treatment reduced intestinal IR-induced histological damage and neutrophil accumulation, limiting inflammation through decrease of NF-ĸB nuclear translocation and fibrotic processes. KYP-2047 treatment restored barrier permeability and structural alteration following intestinal IRI, attenuating neovascular processes compromised by ischemia/reperfusion. Additionally, loss of epithelial cells during intestinal ischemia occurring by apoptosis was limited by KYP-2047 treatment, which showed strong effects counteracting apoptosis and DNA damage.

CONCLUSIONS

These findings provide the first evidence that PREP inhibition through KYP-2047 inhibitor use could be a validate strategy for resolving alterations of intestinal epithelium the pathophysiology of intestinal disease.

Effect of yeast cell wall supplementation on intestinal integrity, digestive enzyme activity and immune traits of broilers

1. The protective layer formed by intestinal epithelial cells acts as a barrier preventing the adhesion of pathogenic bacteria, aids digestion and passage of nutrients and reduces damage caused from toxins on the gastrointestinal tract. This study was conducted to investigate the effects of a yeast cell wall-based product (YCW), on broiler intestinal integrity, digestive enzyme capacity and immune function.2. A 35-d trial involving 246, one-d-of-hatch male broiler chickens was carried out at a trial facility at Agri-Food Biosciences Institute (AFBI, Belfast, UK). Birds were randomly allocated into 6 pens at day of hatch (41 birds/pen; 123 birds/group). Pens were divided into two groups: (1) basal diet and (2) basal diet that incorporated YCW at the manufacturers' recommended inclusion levels (Alltech Inc., Lexington, Kentucky, USA).3. In this study, YCW supplementation affected broiler intestinal morphology resulting in greater crypt depth, villus height and surface area, goblet cell density and mucus layer thickness and lower muscularis mucosae thickness. The digestive enzymes, maltase, sucrase and alkaline phosphatase, were significantly higher in the YCW supplemented group compared to the control. The expression levels of pro-inflammatory cytokines, IL-1β, IL-12 and IL-18, were significantly lower as was necroptotic cell death in YCW supplemented birds.4. In conclusion, under the conditions of this study, YCW supplementation positively affected intestinal health parameters in broilers following 35-d supplementation.

Rictor/Mammalian Target of Rapamycin Complex 2 Signaling Protects Colonocytes from Apoptosis and Prevents Epithelial Barrier Breakdown

Epithelial barrier impairment is a hallmark of several pathologic processes in the gut, including inflammatory bowel diseases. Several intracellular signals prevent apoptosis in intestinal epithelial cells. Herein, we show that in colonocytes, rictor/mammalian target of rapamycin complex 2 (mTORC2) signaling is a prosurvival stimulus. Mechanistically, mTORC2 activates Akt, which, in turn, inhibits apoptosis by phosphorylating B-cell lymphoma 2 (BCL2) associated agonist of cell death (Bad) and preventing caspase-3 activation. Nevertheless, during inflammation, rictor/mTORC2 signaling declines and Akt activity is reduced. Consequently, active caspase-3 increases in surface colonocytes undergoing apoptosis/anoikis and causes epithelial barrier breakdown. Likewise, Rictor ablation in intestinal epithelial cells interrupts mTORC2/Akt signaling and increases apoptosis/anoikis of surface colonocytes without affecting the crypt architecture. The increase in epithelial permeability induced by Rictor ablation produces a mild inflammatory response in the colonic mucosa, but minimally affects the development/establishment of colitis. The data identify a previously unknown mechanism by which rictor/mTORC2 signaling regulates apoptosis/anoikis in intestinal epithelial cells during colitis and clarify its role in the maintenance of the intestinal epithelial barrier.

Oxidative Stress and Pathways of Molecular Hydrogen Effects in Medicine

There are many situations of excessive production of reactive oxygen species (ROS) such as radiation, ischemia/reperfusion (I/R), and inflammation. ROS contribute to and arises from numerous cellular pathologies, diseases, and aging. ROS can cause direct deleterious effects by damaging proteins, lipids, and nucleic acids as well as exert detrimental effects on several cell signaling pathways. However, ROS are important in many cellular functions. The injurious effect of excessive ROS can hypothetically be mitigated by exogenous antioxidants, but clinically this intervention is often not favorable. In contrast, molecular hydrogen provides a variety of advantages for mitigating oxidative stress due to its unique physical and chemical properties. H₂ may be superior to conventional antioxidants, since it can selectively reduce ●OH radicals while preserving important ROS that are otherwise used for normal cellular signaling. Additionally, H₂ exerts many biological effects, including antioxidation, anti-inflammation, anti-apoptosis, and anti-shock. H₂ accomplishes these effects by indirectly regulating signal transduction and gene expression, each of which involves multiple signaling pathways and crosstalk. The Keap1-Nrf2-ARE signaling pathway, which can be activated by H₂, plays a critical role in regulating cellular redox balance, metabolism, and inducing adaptive responses against cellular stress. H₂ also influences the crosstalk among the regulatory mechanisms of autophagy and apoptosis, which involve MAPKs, p53, Nrf2, NF-κB, p38 MAPK, mTOR, etc. The pleiotropic effects of molecular hydrogen on various proteins, molecules and signaling pathways can at least partly explain its almost universal pluripotent therapeutic potential.

Maintenance of gut barrier integrity after injury: Trust your gut microRNAs

The gastrointestinal (GI) tract is a highly dynamic structure essential for digestion, nutrient absorption, and providing an interface to prevent gut bacterial translocation. In order to maintain the barrier function, the gut utilizes many defense mechanisms including proliferation, apoptosis, and apical junctional complexes. Disruption of any of these parameters due to injury or disease could negatively impact the intestinal barrier function and homeostasis resulting in increased intestine inflammation, permeability, bacterial dysbiosis, and tissue damage. MicroRNAs are small noncoding RNA sequences that are master regulators of normal cellular homeostasis. These regulatory molecules affect cellular signaling pathways and potentially serve as candidates for providing a mechanism of impaired gut barrier integrity following GI-related pathologic conditions, ethanol exposure, or trauma such as burn injury. MicroRNAs influence cellular apoptosis, proliferation, apical junction complex expression, inflammation, and the microbiome. Due to their widespread functional affiliations, altered expression of microRNAs are associated with many pathologic conditions. This review explores the role of microRNAs in regulation of intestinal barrier integrity. The studies reviewed demonstrate that microRNAs largely impact intestine barrier function and provide insight behind the observed adverse effects following ethanol and burn injury. Furthermore, these studies suggest that microRNAs are excellent candidates for therapeutic intervention or for biomarkers to manage gut barrier integrity following trauma such as burn injury and other GI-related pathologic conditions.

Yak milk-derived exosomal microRNAs regulate intestinal epithelial cells on proliferation in hypoxic environment

Intestinal epithelial cells (IEC) act as an important intestinal barrier whose function can be impaired upon induction by hypoxia. Although intestinal barrier injuries are preventable by milk-derived exosomal microRNAs (miRNAs), the underlying mechanism remains poorly understood. This study aimed to characterize the effect of yak and cow milk-derived exosomal miRNA on the barrier function of IEC-6 under hypoxic conditions, and explore the mechanism of yak milk exosomal miRNA to relieve the hypoxia stress. First, by Illumina HiSeq 2500 (Illumina Inc., San Diego, CA) sequencing, the miRNA expression was systematically screened, and differential expression of 130 miRNAs was identified with 51 being upregulated and 79 downregulated in yak and cow milk-derived exosomes. Furthermore, the top 20 miRNAs that had a relatively consistent high expression in yak milk exosome were identified, and bta-miR-34a was found to be an effective regulator for alleviating hypoxic injury of IEC-6. In vitro assay of the role of bta-miR-34a on survival of IEC-6 in hypoxia by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) confirmed its effectiveness to significantly increase IEC-6 survival up to 13% for 12 h, and up to 9.5% for 24 h. Investigation on the regulatory relationship between bta-miRNA-34a and the hypoxia-inducible factor/apoptosis signaling pathway provided insights into the possible mechanisms by which bta-miR-34a activated the hypoxia-inducible factor and apoptosis signaling pathway, thus promoting IEC-6 survival. The results of this study suggest an important relationship between miRNA expression and intestine barrier integrity, which facilitated further understanding of the physiological function of yak and cow milk exosomal miRNAs, as well as mechanisms of hypoxia-driven epithelial homeostasis.

Maternal Folic Acid Supplementation Differently Affects the Small Intestinal Phenotype and Gene Expression of Newborn Lambs from Differing Litter Sizes

The purpose of this study was to investigate the effect of maternal dietary folic acid (FA) supplementation during gestation on small intestinal development of newborn lambs of different litter sizes, focusing on the intestinal morphology and development-, apoptosis- and digestion-related genes expression. One hundred and twenty Hu ewes (Ovis aries) were inseminated and randomly allotted to three groups. One group received a control diet [without FA supplementation, control (CON)] and the other two groups received control diets supplemented with different amount of FA [16 or 32 mg FA per kg dry matter (DM), i.e., F16 and F32] during pregnancy. After lambing, according to the dietary FA levels and litter size (twins, TW; triplets, TR), the neonatal lambs were divided into 6 (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) treatment groups. The results showed that the ratio of small intestinal weight to live body weight and the thickness of the intestinal muscle layer in the offspring was enhanced significantly with increasing maternal FA supplementation (p < 0.05). Meanwhile, the expression levels of insulin-like growth factor I (IGF-I), B-cell lymphoma-2 (BCL-2) and sodium/glucose co-transporter-1 (SGLT1) in the small intestines of the newborn lambs were increased, while the opposite was true for Bcl2-associated × (BAX) in response to FA supplementation (p < 0.05). Moreover, the small intestinal weights of twins were significantly higher than those of triplets (p < 0.01), and the expression levels of IGF-I (p < 0.05), sucrase-isomaltase (SI) (p < 0.05) and solute carrier family 2 member 5 (SLC2A5) (p < 0.01) were significantly lower than those in triplets. These findings suggest that maternal FA supplementation could improve the offspring's small intestinal phenotype and the expression of development-, apoptosis- and digestion-related genes, so it could promote the small intestinal development of newborn lambs. Furthermore, the small intestine phenotypic development of twins was generally better than that of triplets, while the expression levels of the above genes of twins were lower than those of triplets.

PARK7 Diminishes Oxidative Stress-Induced Mucosal Damage in Celiac Disease

Coeliac disease (CD) is a chronic, immune-mediated small intestinal enteropathy, accompanied with gluten-triggered oxidative damage of duodenal mucosa. Previously, our research group reported an increased mucosal level of the antioxidant protein Parkinson's disease 7 (PARK7) in children with CD. In the present study, we investigated the role of increased PARK7 level on the epithelial cell and mucosal integrity of the small intestine. The presence of PARK7 was investigated using immunofluorescent staining on duodenal mucosa of children with CD and on FHs74Int duodenal epithelial cells. To investigate the role of oxidative stress, FHs74Int cells were treated with H₂O₂ in the absence or presence of Comp23, a PARK7-binding compound. Intracellular accumulation of reactive oxygen species (ROS) was determined by DCFDA-based assay. Cell viability was measured by MTT, LDH, and Annexin V apoptosis assays. Disruption of cytoskeleton and cell adhesion was investigated by immunofluorescence staining and by real-time RT PCR. Effect of PARK7 on mucosal permeability was investigated ex vivo using intestinal sacs derived from control and Comp-23-pretreated mice. Comp23 treatment reduced the H₂O₂-induced intracellular accumulation of ROS, thus preserving the integrity of the cytoskeleton and also the viability of the FHs74Int cells. Accordingly, Comp23 treatment increased the expression of antioxidants (NRF2, TRX1, GCLC, HMOX1, NQO1), cell-cycle regulators (TP53, CDKN1A, PCNA, BCL2, BAX), and cell adhesion molecules (ZO1, CDH1, VCL, ITGB5) of H₂O₂-treated cells. Pretreatment with Comp23 considerably decreased the small intestinal permeability. In this study, we demonstrate that PARK7-binding Comp23 reduces the oxidative damage of duodenal epithelial cells, via increased expression of NRF2- and P53-regulated genes. Our results suggest that PARK7 plays a significant role in the maintenance of mucosal integrity in CD.

Colitis nucleomigrans: The third type of microscopic colitis (part 2). An ultrastructural study

In the preceding article (part 1), we proposed the third type of microscopic colitis: colitis nucleomigrans (CN). Microscopically, the nuclei of surface‐lining columnar cells were migrated in chain to the middle part of the cells, and apoptotic nuclear debris was scattered in the cytoplasm beneath the nuclei. For ultrastructural analysis, buffered formalin‐fixed biopsy tissue of CN (n = 2) was dug out of paraffin blocks. After deparaffinization, tissue blocks were prepared with conventional sequences. Ultrathin sections were stained with uranyl acetate and lead citrate. Fine morphological preservation was satisfactory even after paraffin embedding. Apoptotic nuclear debris was localized within the cytoplasm beneath the migrated nuclei of the surface‐lining columnar cells. Abnormality of cytoskeletal filaments (actin, cytokeratin and tubulin) was scarcely recognized in the epithelial cytoplasm. Macrophages located in the uppermost part of the lamina propria phagocytized electron‐dense globular materials. Intraepithelial lymphocytes with scattered dense bodies were observed among the columnar cells. We suppose that altered apoptotic processes in the colorectal surface‐lining epithelial cells may be involved in the pathogenesis of CN. Mechanisms of nuclear migration to the unusual position or impairment of nuclear anchoring to the basal situation in the surface‐lining epithelial cells remain unsettled, because cytoskeletal components showed little ultrastructural abnormality.

Colitis nucleomigrans: The third type of microscopic colitis (part 1)

Microscopic colitis (MC), encompassing collagenous colitis and lymphocytic colitis, is featured by chronic diarrhea, normal‐looking endoscopic findings and unique microscopic appearance. After reviewing biopsied nonspecific colitis, we propose the third type of MC: colitis nucleomigrans (CN). Histopathological criteria of CN included: (i) chained nuclear migration to the middle part of the surface‐lining columnar epithelium; (ii) apoptotic nuclear debris scattered below the nuclei; and (iii) mild/moderate chronic inflammation in the lamina propria. Thirty‐three patients (M:F = 20:13; median age 63 years, range 17–88) fulfilled our criteria. Seven cases demonstrated MC‐like clinical/endoscopic features. Mucosal reddening with or without erosion/aphtha was endoscopically observed in the remaining 26 cases with inflammatory bowel disease (IBD)‐like features: occult/gross hematochezia seen in 19, abdominal pain in two and mucin secretion in two. Cleaved caspase‐3‐immunoreactive apoptotic debris appeared more frequently in IBD‐like CN than in MC‐like CN, while CD8‐positive intraepithelial lymphocytes comparably appeared in both. Proton pump inhibitors (PPIs) were administered in five (71%) cases with MC‐like features, and in three diarrhea improved after drug cessation. In IBD‐like CN cases, eight (31%) received PPIs. Four patients received chemotherapy against malignancies. Four patients associated immune‐related disorders. Microscopic appearance of CN also appeared in a remission state of ulcerative colitis (12/20 lesions).

l-Arginine Inhibits Apoptosis of Ovine Intestinal Epithelial Cells through the l-Arginine-Nitric Oxide Pathway

BACKGROUND

In nonruminants, many of the biological roles of l-arginine (Arg) at the intestinal level are mediated through the Arg-nitric oxide (Arg-NO) pathway. Whether the Arg-NO pathway is involved in controlling the immune response and viability in ovine intestinal epithelial cells (IOECs) is unclear.

OBJECTIVES

The current study aimed to examine the role of the Arg-NO pathway in apoptosis, antioxidant capacity, and mitochondrial function of IOECs.

METHODS

The IOECs were incubated in Arg-free DMEM supplemented with 150 μM Arg (CON) or 300 μM Arg (ARG) alone or with 350 μM Nw-nitro-l-arginine methyl ester hydrochloride (l-NAME) (CON + NAME, ARG + NAME) for 24 h. The reactive oxygen species (ROS) concentration, antioxidant capacity, and cell apoptotic percentage were determined.

RESULTS

Arg supplementation decreased (P < 0.05) the ROS concentration (38.9% and 22.7%) and apoptotic cell percentage (57.2% and 54.8%) relative to the CON and CON + NAME groups, respectively. Relative to the CON and ARG treatments, the l-NAME administration decreased (P < 0.05) the mRNA abundance of superoxide dismutase 2 (32% and 21.3%, respectively) and epithelial NO synthase (36% and 29.1%, respectively). Arg supplementation decreased (P < 0.05) the protein abundance of apoptosis antigen 1 (FAS) (52.0% and 43.9%) but increased (P < 0.05) those of nuclear respiratory factor 1 (31.3% and 22.9%) and inducible NO synthase (35.2% and 41.8%) relative to the CON and CON + NAME groups, respectively.

CONCLUSIONS

The inhibition of apoptosis in IOECs due to the increased supply of Arg is associated with the mitochondria- and FAS-dependent pathways through the activity of the Arg-NO pathway. The findings help elucidate the role of the Arg-NO pathway in IOEC growth and apoptosis.

Fabrication, characterization and biological evaluation of silymarin nanoparticles against carbon tetrachloride-induced oxidative stress and genotoxicity in rats

This study aimed to synthesize silymarin nanoparticles (SILNPs) using chitosan nanoparticles as a delivery system and to evaluate their protective effects against CCl₄ in rats. Eight groups of male Sprague-Dawley rats were treated for three weeks included the control group, CCl₄-treated group (100 mg/kg b.w twice a week); SIL-treated group (50 mg/lg b.w); the groups treated daily with low dose (LD) or high dose (HD) of SILNPs (25, 50 mg/kg b.w) and the groups treated with CCl₄ plus SIL, SILNPs (LD) or SILNPs (HD). Blood and tissue samples were collected for different assays. The synthesized SILNPs showed a smooth rounded shape with average particle size of 100 ± 2.8 nm. SILNPs contain the same compounds found in raw SIL and the in vitro release of SILNPs continues till 24 h. The in vivo study revealed that SIL and SILNPs at the low or high dose induced a significant improvement in the hematological parameters, liver and kidney function, lipid profile, serum cytokines, gene expression DNA fragmentation and histology of liver and kidney tissue resulted from CCl₄. It could be concluded that SILNPs can be applied in oral delivery formulations with a potential application value for liver disease therapy.

BCL-2 family deregulation in colorectal cancer: potential for BH3 mimetics in therapy

Apoptosis is a form of programmed cell death that is essential for tissue homeostasis. De-regulation of the balance between proliferation and apoptosis contributes to tumor initiation. Particularly in the colon where apoptosis is a crucial process in intestinal turnover, inhibition of apoptosis facilitates transformation and tumor progression. The BCL-2 family of proteins are key regulators of apoptosis and have been implicated in colorectal cancer (CRC) initiation, progression and resistance to therapy. In this review we outline the current knowledge on the BCL-2 family-regulated intrinsic apoptosis pathway and mechanisms by which it is de-regulated in CRC. We further review BH3 mimetics as a therapeutic opportunity to target this pathway and evaluate their potential for CRC treatment.

Review: Importance of colostrum supply and milk feeding intensity on gastrointestinal and systemic development in calves

Feeding management of the postnatal and preweaning calf has an important impact on calf growth and development during this critical period and affects the health and well-being of the calves. After birth, an immediate and sufficient colostrum supply is a prerequisite for successful calf rearing. Colostrum provides high amounts of nutrient as well as non-nutrient factors that promote the immune system and intestinal maturation of the calf. The maturation and function of the neonatal intestine enable the calf to digest and absorb the nutrients provided by colostrum and milk. Therefore, colostrum intake supports the start of anabolic processes in several tissues, stimulating postnatal body growth and organ development. After the colostrum feeding period, an intensive milk feeding protocol, that is, at least 20% of BW milk intake/day, is required to realise the calf potential for growth and organ development during the preweaning period. Insufficient milk intake delays postnatal growth and may have detrimental effects on organ development, for example, the intestine and the mammary gland. The somatotropic axis as the main postnatal endocrine regulatory system for body growth is stimulated by the intake of high amounts of colostrum and milk and indicates the promotion of anabolic metabolism in calves. The development of the forestomach is an important issue during the preweaning period in calves, and forestomach maturation is best achieved by solid feed intake. Unfortunately, intensive milk-feeding programmes compromise solid feed intake during the first weeks of life. In the more natural situation for beef calves, when milk and solid feed intake occurs at the same time, calves benefit from the high milk intake as evidenced by enhanced body growth and organ maturation without impaired forestomach development during weaning. To realise an intensive milk-feeding programme, it is recommended that the weaning process should not start too early and that solid feed intake should be at a high extent despite intensive milk feeding. A feeding concept based on intensive milk feeding prevents hunger and abnormal behaviour of the calves and fits the principles of animal welfare during preweaning calf rearing. Studies on milk performance in dairy cows indicate that feeding management during early calf rearing influences lifetime performance. Therefore, an intensive milk-feeding programme affects immediate as well as long-term performance, probably by programming metabolic pathways during the preweaning period.

Hydrogen attenuates radiation-induced intestinal damage by reducing oxidative stress and inflammatory response

The small intestine is known to be particularly sensitive to radiation, and the major limiting factor of radiotherapy is the gastrointestinal syndrome that subsequently develops after its administration. The detrimental effects of radiation are mostly mediated via the overproduction of reactive oxygen species (ROS), especially the hydroxyl radical (·OH). Because hydrogen is a selective ·OH scavenger, we hypothesized that hydrogen might exert a protective effect against radiation-induced intestinal damage. Herein, radiation models were built both in mice and in an intestinal crypt epithelial cell (IEC-6) line. In the animal experiment, we demonstrated that hydrogen-rich saline significantly reduced radiation-induced intestinal mucosal damage, improved intestinal function, and increased the survival rate. In addition, radiation-induced oxidative stress damage and systemic inflammatory response were also mitigated by hydrogen treatment. Moreover, hydrogen treatment decreased cell apoptosis and maintained intestinal epithelial cell proliferation in mice. In vitro experiments using the IEC-6 cell line showed that hydrogen-rich medium significantly inhibited ROS formation, maintained cell viability, and inhibited cell apoptosis. Importantly, hydrogen treatment prevented mitochondrial depolarization, cytochrome c release, and activity of caspase-3, caspase-9, and PARP. Moreover, the decreased expression of Bcl-xl and Bcl-2 and the increased expression of Bax protein were also blocked by hydrogen treatment. In conclusion, our study concurrently demonstrated that hydrogen provides an obviously protective effect on radiation-induced intestinal and cell injuries. Our work demonstrated that this protective effect might be due to the blockage of the mitochondrial apoptotic pathway.

N-Acetyl Serotonin Alleviates Oxidative Damage by Activating Nuclear Factor Erythroid 2-Related Factor 2 Signaling in Porcine Enterocytes

Apoptosis of intestinal epithelial cells following oxidative stress is a major cause of mucosal barrier dysfunction and is associated with the pathogenesis of various gastrointestinal diseases. Although L-tryptophan (Trp) is known to improve intestinal integrity and function, a beneficial effect of N-acetyl serotonin (NAS), a metabolite of Trp, on the apoptosis of enterocytes and the underlying mechanisms remain largely unknown. In the present study, we showed that porcine enterocytes treated with 4-hydroxy-2-nonenal (4-HNE), a metabolite of lipid peroxidation, led to upregulation of apoptotic proteins, including Bax and cleaved caspase-3, and reduction of tight junction proteins. These effects of 4-HNE were significantly abrogated by NAS. In addition, NAS reduced ROS accumulation while increasing the intracellular concentration of glutathione (GSH), and the abundance of the Nrf2 protein in the nucleus and its downstream target proteins. Importantly, these protective effects of NAS were abrogated by Atra, an inhibitor of Nrf2, indicating a dependence on Nrf2 signaling. Taken together, we demonstrated that NAS attenuated oxidative stress-induced cellular injury in porcine enterocytes by regulating Nrf2 signaling. These findings provide new insights into a functional role of NAS in maintaining intestinal homeostasis.

Salvadora persica protects mouse intestine from eimeriosis

Eimeriosis is a global poultry health problem. In the current study, we investigated the role of Salvadora persica leaf extracts (SE) against murine eimeriosis induced by Eimeria papillata. The infection induced an oocyst output of 6242 ± 731 oocysts/g feces. After treatment with 300 mg⁄kg SE, the oocysts expelled in feces decreased by approximately 3-fold. In addition, the total number of E. papillata in the parasitic stage decreased in the jejunum of mice after treatment with SE. In addition, SE significantly reduced the number of apoptotic cells by approximately 2-fold in the infected jejunum. SE ameliorated the changes in glutathione, malondialdehyde, and catalase due to E. papillata infection. Finally, SE regulated the cytokine genes, interleukin (IL)-1β, IL-6, interferon-γ, and tumor necrosis factor-α, and the apoptotic genes, B-cell lymphoma-2, Bax, and Caspase-3. SE protects the jejunum from E. papillata induced injury and may have potential therapeutic value as a food additive during eimeriosis.

AXIN2+ Pericentral Hepatocytes Have Limited Contributions to Liver Homeostasis and Regeneration

The existence of specialized liver stem cell populations, including AXIN2⁺ pericentral hepatocytes, that safeguard homeostasis and repair has been controversial. Here, using AXIN2 lineage tracing in BAC-transgenic mice, we confirm the regenerative potential of intestinal stem cells (ISCs) but find limited roles for pericentral hepatocytes in liver parenchyma homeostasis. Liver regrowth following partial hepatectomy is enabled by proliferation of hepatocytes throughout the liver, rather than by a pericentral population. Periportal hepatocyte injury triggers local repair as well as auxiliary proliferation in all liver zones. DTA-mediated ablation of AXIN2⁺ pericentral hepatocytes transiently disrupts this zone, which is reestablished by conversion of pericentral vein-juxtaposed glutamine synthetase (GS)^- hepatocytes into GS⁺ hepatocytes and by compensatory proliferation of hepatocytes across liver zones. These findings show hepatocytes throughout the liver can upregulate AXIN2 and LGR5 after injury and contribute to liver regeneration on demand, without zonal dominance by a putative pericentral stem cell population.

Loss of C/EBPδ enhances apoptosis of intestinal epithelial cells and exacerbates experimental colitis in mice

Inflammatory bowel diseases (IBDs) are characterized by chronic inflammation involving intestinal tissue damage, which include ulcerative colitis and Crohn's disease as major entities. Accumulating evidence suggests that excessive apoptosis of intestinal epithelial cells (IECs) contributes to the development of IBD. It was recently reported that the transcription factor CCAAT/enhancer-binding protein delta (C/EBPδ) is involved in inflammation; however, its role in colitis remains unclear. Here, we found that C/EBPδ knockout mice showed enhanced susceptibility to dextran sodium sulfate (DSS)-induced colitis, a mouse model of IBD, which was associated with severe colonic inflammation and mucosal damage with increased IEC apoptosis. Additionally, DSS stimulation induced increased expression of pro-apoptotic BH3-only protein Bim in the colon of C/EBPδ knockout mice. Collectively, our findings demonstrate that C/EBPδ plays an essential role in suppressing DSS-induced colitis, likely by attenuating IEC apoptosis.

A New Approach for the Prevention and Treatment of Cardiovascular Disorders. Molecular Hydrogen Significantly Reduces the Effects of Oxidative Stress

Cardiovascular diseases are the most common causes of morbidity and mortality worldwide. Redox dysregulation and a dyshomeostasis of inflammation arise from, and result in, cellular aberrations and pathological conditions, which lead to cardiovascular diseases. Despite years of intensive research, there is still no safe and effective method for their prevention and treatment. Recently, molecular hydrogen has been investigated in preclinical and clinical studies on various diseases associated with oxidative and inflammatory stress such as radiation-induced heart disease, ischemia-reperfusion injury, myocardial and brain infarction, storage of the heart, heart transplantation, etc. Hydrogen is primarily administered via inhalation, drinking hydrogen-rich water, or injection of hydrogen-rich saline. It favorably modulates signal transduction and gene expression resulting in suppression of proinflammatory cytokines, excess ROS production, and in the activation of the Nrf2 antioxidant transcription factor. Although H2 appears to be an important biological molecule with anti-oxidant, anti-inflammatory, and anti-apoptotic effects, the exact mechanisms of action remain elusive. There is no reported clinical toxicity; however, some data suggests that H2 has a mild hormetic-like effect, which likely mediate some of its benefits. The mechanistic data, coupled with the pre-clinical and clinical studies, suggest that H2 may be useful for ROS/inflammation-induced cardiotoxicity and other conditions.

Bacillus amyloliquefaciens Ameliorates H2O2-Induced Oxidative Damage by Regulating Transporters, Tight Junctions, and Apoptosis Gene Expression in Cell Line IPEC-1

Probiotics have always been considered as a supplementary therapy for many diseases especially gut disorders. The absorption and barrier function of the gut play a vital role in the maintenance of body homeostasis. This study was to investigate the protective effects of Bacillus amyloliquefaciens SC06 (Ba) on H₂O₂-induced oxidative stress on intestinal porcine epithelial cells (IPEC-1) based on the level of gene expression. We demonstrated that Ba was a safe probiotic strain in the first place. Results showed that treatment with H₂O₂ significantly increased the mRNA expression of absorptive transporters glucose transporter 2 (GLUT2), Ala/Ser/Cys/Thr transporter 1 (ASCT1), and ASCT2 compared with the control group. Meanwhile, oxidative stress induced a significant improvement in the mRNA expression of occludin (OCLN) and caspase-3, and remarkably inhibited the expression of L-type amino acid transporter 1 (LAT1) or B cell lymphoma-2 (Bcl-2), respectively. Pretreatment with Ba dramatically reversed the disturbance induced by oxidative stress on the mRNA expression of ASCT1, ASCT2, and OCLN, which also significantly prevented H₂O₂-inhibited LAT1 and Bcl-2 mRNA expression. However, Ba failed to exert any significant protective effect on GLUT2 and caspase-3 mRNA expression. We concluded that pretreatment with Ba could alleviate the damage caused by oxidative stress to a certain extent and conferred a protective effect to the intestine.

KCa3.1 Transgene Induction in Murine Intestinal Epithelium Causes Duodenal Chyme Accumulation and Impairs Duodenal Contractility

The epithelial intermediate-conductance calcium/calmodulin-regulated KCa3.1 channel is considered to be a regulator of intestine function by controlling chloride secretion and water/salt balance. Yet, little is known about the functional importance of KCa3.1 in the intestinal epithelium in vivo. Our objective was to determine the impact of epithelial-specific inducible overexpression of a KCa3.1 transgene (KCa3.1+) and of inducible suppression (KCa3.1−) on intestinal homeostasis and function in mice. KCa3.1 overexpression in the duodenal epithelium of doxycycline (DOX)-treated KCa3.1+ mice was 40-fold above the control levels. Overexpression caused an inflated duodenum and doubling of the chyme content. Histology showed conserved architecture of crypts, villi, and smooth muscle. Unaltered proliferating cell nuclear antigen (PCNA) immune reactivity and reduced amounts of terminal deoxynucleotide transferase mediated X-dUTP nick end labeling (TUNEL)-positive apoptotic cells in villi indicated lower epithelial turnover. Myography showed a reduction in the frequency of spontaneous propulsive muscle contractions with no change in amplitude. The amount of stool in the colon was increased and the frequency of colonic contractions was reduced in KCa3.1+ animals. Senicapoc treatment prevented the phenotype. Suppression of KCa3.1 in DOX-treated KCa3.1− mice caused no overt intestinal phenotype. In conclusion, inducible KCa3.1 overexpression alters intestinal functions by increasing the chyme content and reducing spontaneous contractions and epithelial apoptosis. Induction of epithelial KCa3.1 can play a mechanistic role in the process of adaptation of the intestine.

Zinc citrate incorporation with whey protein nanoparticles alleviate the oxidative stress complication and modulate gene expression in the liver of rats

This study aimed to evaluate the hepatoprotective effect of whey protein nanoparticles (WP-NPs) coated Zinc citrate (Zn) against oxidative stress complications and disturbances in gene expression in rats treated with CCl4. WP-NPs were used to coat Zn at three levels and amino acids content was determined in WP-NPs and the fabrications. Seven groups of male albino rats included the control group, CCl4-treated group (0.5 ml/100 g b.w) and the groups treated with CCl4 plus WP-NPs, Zn and the three Zn-WP-NPs fabrications. Blood and liver samples were collected for different analysis. Particles sizes were 95, 142, 196 and 228 nm and zeta potential values were -95, -114, -85 and -79 for WP-NPs and the three Zn-WP-NPs fabrications, respectively. Twelve amino acids were found in WP-NPs and this number was decreased by increasing Zn content. WP-NPs, Zn and the Zn coated WP-NPs counteracted the disturbances in biochemical, parameters, gene expression and histological changes in CCl4-treated rats and Zn-WP-NPs was more effective at the low dose. It could be concluded that WP-NPs enhance the effect of Zn and can be used for coating Zn in the preparation of Zn supplementation to enhance its effect and counteract the side effect of excess Zn.

l-Arginine Protects Ovine Intestinal Epithelial Cells from Lipopolysaccharide-Induced Apoptosis through Alleviating Oxidative Stress

This research aims to explore the effect of l-arginine (Arg) upon lipopolysaccharide (LPS)-induced induction of the oxidative stress as well as subsequent apoptosis within ovine intestinal epithelial cells (IOECs). Through a 16 h incubation, cells were divided into four groups and the medium was replaced with different medium as follows: (1) control (Con), Arg-free Dulbecco's modified Eagle's F12 Ham medium (DMEM); (2) Arg treatment, Arg-free DMEM supplemented with 100 μM Arg; (3) LPS treatment, Arg-free DMEM supplemented with 10 μg/mL LPS; (4) LPS with Arg treatment, Arg-free DMEM supplemented with both 10 μg/mL LPS and 100 μM Arg. After culturing for 24 h in different mediums, some characteristics of cells in the four groups were measured. Addition of Arg increased cell viability induced with LPS compared with the LPS group ( p < 0.05). Arg significantly decreased the release of dehydrogenase (LDH) and the production of malonaldehyde (MDA) ( p < 0.05) within IOECs challenged by the LPS. Compared with the LPS group, cells treated with Arg and Arg + LPS increased ( p < 0.05) mRNA as well as protein expression of glutathione peroxidase 1 (GPx1), catalase (CAT), superoxide dismutase 2 (SOD2), B-cell lymphoma 2 (Bcl2), quinone oxidoreductase 1 (NQO1), heme oxygenase (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2). IOEC treatment with Arg reduced significantly ( p < 0.05) apoptosis induced by the LPS (12.58 ± 0.79%). The results showed that Arg promoted the protein expression of Nrf2, up-regulated expression of the phase II metabolizing enzymes (NQO1 and HO-1), as well as antioxidative enzymes (GPx1, CAT, and SOD2) for alleviating oxidative injury and protected IOECs from LPS-induced apoptosis.

Yak-milk-derived exosomes promote proliferation of intestinal epithelial cells in an hypoxic environment

Intestinal epithelial cells (IEC) are an important part of the intestinal barrier. Barrier function was disrupted under hypoxia, but milk-derived exosomes can regulate the intestinal barrier function. However, the mechanisms underlying the association between yak milk exosomes and hypoxia in IEC remain poorly understood. In this follow-up study, we proposed an effective optimization method for purifying yak-milk-derived exosomes. The Western blot analyses indicated that the expression of the proteins of the endosomal sorting complexes required for transport (TSG101), proteins of the tetraspanin family (CD63), and heat shock protein 70 (Hsp-70) proteins from yak-milk-derived exosomes were significantly higher than those in cow-milk-derived exosomes. Flow cytometry analysis showed that yak milk had 3.7 times the number of exosomes compared with cow milk. Moreover, we explored whether yak milk exosomes could facilitate intestinal cell survival under hypoxic conditions in vitro. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide results showed that yak-milk-derived exosomes significantly increased survival of IEC-6 cells with rates of up to 29% for cells incubated in hypoxic conditions for 12 h, compared with those of cow-milk-derived exosomes posttreatment (rates of up to 22% for cells incubated in hypoxic conditions for 12 h). Confocal microscopy revealed that the IEC-6 cells uptake more yak-milk-derived exosomes than cow milk in hypoxic conditions. Furthermore, the Western blot analyses indicated that yak-milk-derived exosomes significantly promote oxygen-sensitive prolyl hydroxylase (PHD)-1 expression and decrease the expression of hypoxia-inducible factor-α and its downstream target vascular endothelial growth factor (VEGF) in the IEC-6 cells. Further, yak-milk-derived exosomes significantly inhibited p53 levels. In conclusion, our findings demonstrate that yak-milk-derived exosomes more effectively activate the hypoxia-inducible factor signaling pathway, thus promoting IEC-6 cell survival, which may result in higher hypoxia tolerance than cow-milk-derived exosomes.

On cell death in the intestinal epithelium and its impact on gut homeostasis

PURPOSE OF REVIEW

Both apoptotic and nonapoptotic cell extrusion preserve the barrier functions of epithelia. Live cell extrusion is the paradigm for homeostatic renewal of intestinal epithelial cells (IEC). By extension, as extruded cells are not apoptotic, this form of cell shedding is thought to be largely ignored by lamina propria phagocytes and without immune consequence.

RECENT FINDINGS

Visualization of apoptotic IEC inside distinct subsets of intestinal phagocytes during homeostasis has highlighted apoptosis as a normal component of the natural turnover of the intestinal epithelium. Analysis of phagocytes with or without apoptotic IEC corpses has shown how apoptotic IEC constrain inflammatory pathways within phagocytes and induce immunosuppressive regulatory CD4 T-cell differentiation. Many of the genes involved overlap with susceptibility genes for inflammatory bowel disease (IBD).

SUMMARY

Excessive IEC death and loss-of-barrier function is characteristic of IBD. As regulatory and tolerogenic mechanisms are broken in IBD, a molecular understanding of the precise triggers and modes of IEC death as well as their consequences on intestinal inflammation is necessary. This characterization should guide new therapies that restore homeostatic apoptosis, along with its associated programs of immune tolerance and immunosuppression, to achieve mucosal healing and long-term remission.

Thirty-eight-negative kinase 1 mediates trauma-induced intestinal injury and multi-organ failure

Dysregulated intestinal epithelial apoptosis initiates gut injury, alters the intestinal barrier, and can facilitate bacterial translocation leading to a systemic inflammatory response syndrome (SIRS) and/or multi-organ dysfunction syndrome (MODS). A variety of gastrointestinal disorders, including inflammatory bowel disease, have been linked to intestinal apoptosis. Similarly, intestinal hyperpermeability and gut failure occur in critically ill patients, putting the gut at the center of SIRS pathology. Regulation of apoptosis and immune-modulatory functions have been ascribed to Thirty-eight-negative kinase 1 (TNK1), whose activity is regulated merely by expression. We investigated the effect of TNK1 on intestinal integrity and its role in MODS. TNK1 expression induced crypt-specific apoptosis, leading to bacterial translocation, subsequent septic shock, and early death. Mechanistically, TNK1 expression in vivo resulted in STAT3 phosphorylation, nuclear translocation of p65, and release of IL-6 and TNF-α. A TNF-α neutralizing antibody partially blocked development of intestinal damage. Conversely, gut-specific deletion of TNK1 protected the intestinal mucosa from experimental colitis and prevented cytokine release in the gut. Finally, TNK1 was found to be deregulated in the gut in murine and porcine trauma models and human inflammatory bowel disease. Thus, TNK1 might be a target during MODS to prevent damage in several organs, notably the gut.