Severity Of DSS-induced Colitis Research Articles

P0057 METTL3 potentiates aged CD4+T cell response via programming effector differentiation in elderly ulcerative colitis

Abstract Background The burden of IBD in the elderly is increasing globally. However, the mechanisms underlying the age-related IBD susceptibility remain unclear. Aging leads to a progressive functional decline of the immune system, rendering the elderly increasingly susceptible to inflammatory and autoimmune disease. As a fundamental mRNA modification, N6-methyladenosine (m6A) participates in various pathological processes. However, the role of METTL3-mediated m6A RNA modification in elderly IBD remains unclear. Herein, we sought to determine the role of immunosenescence in age-dependent colitis and to explore the underlying mechanisms. Methods Young (2-3 months), middle-aged (10-12 months), and aged (20-24 months) mice were established models of colitis by 2% dextran sulfate sodium salt (DSS) treatment. We detected the senescence-associated-β-galactosidase (SA-β-Gal) activity in lymphocytes isolated from colon of mice. Single-cell and bulk RNA-seq of colonic immune cells in mice with different ages were performed to investigate the precise molecular mechanisms. CD4+CD25-CD45RBhi T cell adoptive transfer model was used to further analyze the role of senescent CD4+T cells in colitis. Mettl3fl/lfCd4Cre mice were obtained to explicit role of METTL3 in regulating CD4+T cell senescence. Results Ageing increased the severity of DSS-induced colitis. CD4+T cell senescence was implicated in the progression of aging-related experimental colitis, exhibiting an increase of SA-β-Gal and accumulation of CD4+ effector memory T (TEM) cells in colon. Aged colonic CD4+ T cells generate higher levels of IFN-γ and IL-17 comparing to young colonic CD4+ T cells. Single-cell analysis revealed that aging increased colonic CD4+ TEM cells, which were associated with T cell-mediated cytotoxicity and cytokine-mediated signaling pathway. Adoptive transfer of aged CD4+CD25-CD45RBhi T cells to Rag-/- mice induced more severe colitis compared with young CD4+CD25-CD45RBhi T cells transfer. Aged CD4+T potentiates Th1/Th17/Tfh differentiation and exacerbates the progression of colitis. METTL3 was increased in aged colonic CD4+T cells. Inhibiting METTL3 in CD4+T cell protects from cellular senescence, effector differentiation and colitis. Conclusion These results provide a significant insight into the contribution of senescent CD4+ T cells to age-dependent colitis and provide an attractive possibility that targeting T cell specifically might be a potential strategy to treat elderly IBD patients.

P0177 Dietary prevention of undernutrition reduces intestinal inflammation in a DSS-induced model of colitis and is associated with anti-inflammatory metabolites-producing bacteria

Abstract Background Patients with inflammatory bowel diseases (IBD) have a high-risk for undernutrition1. Undernutrition is associated with higher complications such as an increased mortality rate, a higher disease activity and an impaired quality of life in IBD patients. The aim of the present study was to assess whether dietary prevention of undernutrition may alleviate intestinal inflammation in mice with colitis. Methods Mice were fed with an enriched diet (ED; 4.7 kcal/g, 38% kcal from milk fat, 29% kcal from sucrose) or a standard diet (SD; 3.9 kcal/g, 8% kcal from milk fat) for 31 days. Colitis was chemically induced by 1% dextran sulfate sodium (DSS) in male C57BL/6 mice for 7 days. Colitis severity was assessed by monitoring inflammation-related biomarkers, as colon weight/length ratio and fecal calprotectin. Gut microbiota composition was determined by 16S rRNA gene sequencing performed on DNA extracted from cecal contents. Body weight and body composition were recorded. Results In SD-fed mice, DSS induced body weight loss (p<0.01) associated to a decrease of fat and lean mass (p<0.01). In mice with DSS-induced colitis, ED for 3 weeks prevented body weight loss (p<0.001) and body composition alteration. ED prevented DSS-induced higher colon weight/length ratio and fecal calprotectin. Compared to SD, ED significantly increased relative abundance of 8 bacterial species, including Eisenbergiella tayi (log2FC=3.8474, p_adj<0.01) and Lactococcus lactis (log2FC=1.6034, p_adj<0.05) (Figure 1A), which are producing anti-inflammatory metabolites such as butyrate, lactate or succinate. Relative abundances of Pseudoflavonifractor capillosus and Vescimonas coprocola were negatively correlated with inflammatory markers, such as fecal calprotectin levels (r=-0.7347, p:adj=0.0332; r=-0.7846, p=0.0265, respectively) (Figure 1B). Conclusion Prevention of undernutrition by ED reduces DSS-induced colitis severity and is associated with higher anti-inflammatory metabolites-producing bacteria. Further studies are now required to understand the underlying mechanisms involved in these ED-induced effects.

Brief Disruption of Circadian Rhythms Alters Intestinal Barrier Integrity and Modulates DSS-Induced Colitis Severity in Mice.

Physiological processes in organisms exhibit circadian rhythms that optimize fitness and anticipate environmental changes. Luminal signals such as food or metabolites synchronize bowel activity, and disruptions in these rhythms are linked to metabolic disorders and gastrointestinal inflammation. To characterize the intrinsic intestinal rhythms and assess disruptions due to continuous darkness or light exposure, C57BL/6 mice were exposed to standard light-dark conditions or continuous light/darkness for 48h, with evaluations at four timepoints. We assessed intestinal morphology, mucus production, nitric oxide levels and permeability. Under standard light: dark cycles, mice showed changes in intestinal morphology consistent with normal tract physiology. Continuous light exposure caused marked alterations in the small intestine´s epithelium and lamina propria, reduced nitric oxide production in the colon, and predominant neutral mucins. Enhanced permeability was indicated by higher FITC-dextran uptake and increased frequency of IgG-coated bacteria. Additionally, the 48h-disruption influenced DSS-induced colitis with attenuation in L:L group, or exacerbation in D:D group, of clinical signs. These findings highlight the critical role of circadian rhythms in gut histoarchitecture and function, demonstrating that short-term disruptions in light-dark cycles can compromise intestinal barrier integrity and impact inflammatory outcomes.

Fermented Soymilk with Probiotic Lactobacilli and Bifidobacterium Strains Ameliorates Dextran-Sulfate-Sodium-Induced Colitis in Rats.

Background: Current treatments for inflammatory bowel disease (IBD) are relatively futile and the extended use of drugs may reduce effectiveness. Several probiotic strains have shown promise in relieving/treating IBD symptoms. Objectives: The current study investigated the impact of fermented soymilk with a mixture of probiotic starter cultures containing Lactobacillus rhamnosus, L. casei, L. plantarum, L. acidophilus, Bifidobacterium longum, and B. animalis subsp. lactis in rats with dextran sulfate sodium (DSS)-induced colitis compared to control. Methods: Rats were randomly assigned to five groups (5 rats/group; n = 25): G1: negative normal control; G2: positive control (DSS); G3: DSS with sulfasalazine (DSS-Z); G4: DSS with soymilk (DSS-SM), and G5: DSS with fermented soymilk (DSS-FSM). Parameters monitored included the following: the disease activity index (DAI), macroscopic and histological assessments of colitis, and a fecal microbial analysis performed to assess the severity of inflammation and ulceration. Results: The DSS-FSM rats group exhibited lower DAI scores (p < 0.05) than other treated groups during the induction period. A macroscopical examination revealed no ulceration or swelling in the intestinal mucosa of rats in the DSS-FSM-treated group, resembling the findings in the negative control group. In the positive control (DSS group), the colon tissue showed increased inflammation (p < 0.05), whereas those in the DSS-SM- and DSS-FSM-treated rats groups did not show significant macroscopic scores of colitis. The positive DSS control and DSS-Z groups had crypt erosion and ulceration areas, severe crypt damage, and epithelial surface erosion, which were absent in the negative control and DSS-FSM groups. The counts of Lactobacillus spp. and Bifidobacterium spp. remained stable in both G1 and G5 over 4 weeks. The consumption of fermented soymilk with a mixture of probiotics could minimize the severity of DSS-induced colitis in rats. Conclusion, it was found that fermented soymilk containing Lactobacilli and Bifidobacterium might be an effective vehicle for reducing the severity of DSS-induced colitis in rats.

The Role of Dicrocoelium dendriticum Egg Antigen in Colitis: A Molecular, Pathological and Serological Study in an Experimental Model of C57BL/6 Mice.

Inflammatory bowel disease (IBD) is a chronic and recurrent disease of the gastrointestinal tract that enhances the chance of developing colorectal cancer. Since standard treatments such as Mesalazine have limited effectiveness and are often accompanied by numerous side effects, the use of immune modulators derived from worms has been proposed as a new immunotherapy method for inflammatory diseases such as ulcerative colitis. The aim of this study is to investigate the protective effects of D. dendriticum egg antigen on DSS-induced colitis in C57BL/6 mice. D. dendriticum egg antigen was extracted and DSS (3.5%) was used to induce colitis in mice. Treatment and prophylaxis included intraperitoneal injections of D. dendriticum egg antigen. Histopathological indicators and the disease activity index (DAI), including weight loss, rectal bleeding, stool consistency, and rectal prolapse, were used to assess the severity of colitis. Real-time PCR measured the expression of transforming growth factor-β (TGF-β) and interleukin-17 (IL-17), while ELISA determined the concentration of these cytokines. Treatment with D. dendriticum egg antigen significantly improved the clinical symptoms and decreased the severity of DSS-induced colitis. Furthermore, D. dendriticum egg antigen increased the expression of TGF-β mRNA and reduced the expression of IL-17 mRNA, leading to a positive adjustment in the regulation of proteins and reduction of inflammatory proteins. As a result, the macroscopic, microscopic inflammation and activity index (DAI) of DSS-induced decreased. D. dendriticum egg antigen provides a promising new way to modulate the immune system and improve ulcerative colitis.

The Severity of DSS-Induced Colitis Is Independent of the SCFA-FFAR2/3-GLP-1 Pathway Despite SCFAs Inducing GLP-1 Secretion via FFAR2/3.

Short-chain fatty acids (SCFAs) are the major microbial metabolites produced from the fermentation of dietary fiber in the gut. They are recognised as secretagogues of the glucagon-like peptides, GLP-1 and GLP-2, likely mediated by the activation of free fatty acid receptors 2 and 3 (FFAR2 and 3) expressed on enteroendocrine L-cells. Fiber-deficient diets are associated with decreased intestinal function and decreased colonic GLP-1 and GLP-2 content. Here, we speculated that the lowered colonic GLP-1 observed following a fiber-free diet was a consequence of decreased SCFA production and a subsequent decrease in FFAR2/3 activation. Furthermore, we explored the consequences of a fiber-free diet followed by intestinal injury, and we mechanistically explored the SCFA-FFAR2/3-GLP-1 pathway to explain the increased severity. Colonic luminal content from mice fed either a fiber-free or chow diet were analysed for SCFA content by LC-MS. FFAR2/3 receptor contributions to SCFA-mediated colonic GLP-1 secretion were assessed in isolated perfused preparations of the colon from FFAR2/3 double knockout (KO) and wild-type (WT) mice. Colitis was induced by the delivery of 3% dextran sulfate sodium (DSS) for 4 days in the drinking water of mice exposed to a fiber-free diet for 21 days. Colitis was induced by the delivery of 3% DSS for 7 days in FFAR2/3 KO mice. The removal of dietary fiber significantly decreased SCFA concentrations in the luminal contents of fiber-free fed mice compared to chow-fed mice. In the perfused colon, luminal SCFAs significantly increased colonic GLP-1 secretion in WT mice but not in FFAR2/3 KO mice. In the DSS-induced colitis model, the removal of dietary fiber increased the severity and prevented the recovery from intestinal injury. Additionally, colitis severity was similar in FFAR2/3 KO and WT mice after DSS application. In conclusion, the results confirm that the removal of dietary fiber is sufficient to decrease the colonic concentrations of SCFAs. Additionally, we show that a fiber-free diet predisposes the colon to increased intestinal injury, but this effect is independent of FFAR2 and FFAR3 signalling; therefore, it is unlikely that a fiber-free diet induces a decrease in luminal SCFAs and sensitivity to intestinal disease involves the SCFA-FFAR2/3-GLP-1 pathway.

DOP84 Colonic CD4+ T cell senescence is implicated in the progression of experimental colitis in aged mice

Abstract Background Evidence from recent epidemiological data suggests that the burden of IBD in the elderly is increasing globally. However, the mechanisms underlying the age-related IBD susceptibility remain elusive. Aging leads to a progressive functional decline of the immune system, rendering the elderly increasingly susceptible to autoimmune disease. Herein, we sought to determine the role of immunosenescence in age-dependent colitis and to explore the underlying mechanisms. Methods Young (2-3 months), middle-aged (10-12 months), and aged (20-24 months) mice were established models of colitis by 2% dextran sulfate sodium salt (DSS) treatment. Weight loss, colon length, disease activity indexes (DAI) and histological scores were evaluated to assess the severity of colitis. Using a second-generation fluorogenic substrate for β-galactosidase and multi-parameter flow cytometry, we detected the senescence-associated β-galactosidase (SA-βGal) activity in lymphocytes isolated from colon, including CD4+ T cells, CD8+ T cells, B cells, natural killer cells, microphages, neutrophils and dendritic cells. Based on the immunocytes that exhibit greatest age-related increases in SA-βGal activity, inflammatory cytokines such as TNF-α、IFN-γ、IL-17 were evaluated in senescent immunocytes through flow cytometry. Single-cell and bulk RNA-seq of colonic immune cells in mice with different ages were performed to further investigate the precise molecular mechanisms. Results Ageing increased the severity of DSS-induced colitis wherein aged mice exhibited worsened weight loss, shortened colon length, higher DAI and histological scores compared to young mice. The greatest age-associated increases of SA-βGal activity were observed in colonic CD4+ T cell populations. Additionally, aging resulted in systemic activation of CD4+ T cells, exhibiting an expansion of CD4+ effector memory T (TEM) cells in colon, as well as in spleen. Aged colonic CD4+ T cells generate higher levels of IFN-γ and IL-17 comparing to young colonic CD4+ T cells, especially in status of colitis. Moreover, the accumulated CD4+ TEM cells in the aged colon were the main source of IL-17 production. Single-cell analysis revealed that aging increased colonic CD4+ TEM cells, which were associated with T cell-mediated cytotoxicity and cytokine-mediated signaling pathway. Splenic CD4+ TEM cells isolated from aged colitis mice were confirmed to involve in cellular senescence, Th17 differentiation and inflammatory signaling pathway through bulk RNA-seq. Conclusion These results provide a significant insight into the contribution of senescent CD4+ T cells to age-dependent colitis and provide an attractive possibility that targeting T cell specifically might be a potential strategy to treat elderly IBD patients.

Vitamin D/vitamin D receptor protects intestinal barrier against colitis by positively regulating Notch pathway.

Vitamin D/Vitamin D receptor (VD/VDR) signaling and the Notch pathway are involved in intestinal barrier restoration in colitis; however, their relationship and underlying mechanism are largely unknown. Therefore, this study aimed to investigate the role and mechanism of VD/VDR and the Notch pathways in intestinal barrier protection. Genetic Vdr knockout (VDR KO) and VD deficient (VDd) mice were established, and colitis was induced by feeding 2.5% dextran sodium sulfate (DSS) water. Mechanistic studies, including real-time PCR, immunofluorescence, Western blotting and dual-luciferase reporter assays, were performed on cultured Caco-2 cells and intestinal organoids. VD deficiency and VDR genetical KO increased the severity of DSS-induced colitis in mice, which presented a higher disease activity index score, increased intestinal permeability, and more severe intestinal histological damage than controls, accompanied by decreased and disrupted claudin-1 and claudin-3. Moreover, inhibition of Notch pathway by LY411,575 aggravated the severity of DSS-induced colitis and intestinal injury. In Caco-2 cells and intestinal organoids, the expression of Notch-1, N1ICD and Hes1 decreased upon downregulation or KO of VDR but increased upon paricalcitol (PAR, a VDR agonist) treatment. Meanwhile, PAR rescued claudin-1 and claudin-3 impairments that resulted from TNF-α exposure but failed to restore claudin-3 upon Notch inhibition. The dual-luciferase reporter assay further suggested that VD/VDR positively regulated the Notch signaling pathway by modulating Notch-1 transcription. VD/VDR positively modulates Notch activation by promoting Notch-1 transcription to maintain intestinal tight junction integrity and barrier function. This highlights the VD/VDR-Notch pathway as a potential new therapeutic target for protecting the intestinal barrier against ulcerative colitis.

Gut Microbiota-mediated Alleviation of Dextran Sulfate Sodium-induced Colitis in Mice

Background and AimsGut dysbiosis characterized by an imbalanced microbiota is closely involved in the pathogenesis of a widespread gastrointestinal inflammatory disorder, inflammatory bowel disease (IBD). However, it is unclear how the complex intestinal microbiota affects development or resistant of mucosal inflammation. Our aim was to investigate the impact of the gut microbiota on susceptibility in a mouse model of ulcerative colitis. MethodsWe compared the susceptibility to dextran sulfate sodium (DSS)-induced colitis of inbred BALB/c mice obtained from the three main distributors of laboratory animals in Japan. Clinical symptoms of the colitis and the faecal microbiota were assessed. Cohousing approach was used to identify whether the gut microbiota is a primary factor determining disease susceptibility. ResultsHere, we showed differences in the susceptibility of BALB/c mice from the vendors to DSS colitis. Analysis of the gut microbiota using 16S rRNA sequencing revealed clear separation of the gut microbial composition among mice from the vendors. Notably, the abundance of the phylum Actinobacteriota was strongly associated with disease activity. We also observed the expansion of butyrate-producing Roseburia species in mice with decreased susceptibility of the disease. Further cohousing experiments showed that variation in clinical outcomes was more correlated with the gut microbiota than genetic variants among substrains from different suppliers. ConclusionsA BALB/c substrain that was resistant to DSS-induced colitis was observed, and the severity of DSS-induced colitis was mainly influenced by the gut microbiota. Targeting butyrate-producing bacteria could have therapeutic potential for ulcerative colitis.

Moluodan promotes DSS-induced intestinal inflammation involving the reprogram of macrophage function and polarization

Ethnopharmacological relevanceMoluodan (MLD) is a traditional Chinese medicine that is composed of 18 herbal medicines based on traditional Chinese medicine theory and practice. It has long been used in treating chronic gastritis and its components were traditionally used in dealing with intestinal inflammation. However, its specific pharmacological mechanism is still unclear. Aim of the studyThe upper and lower digestive tract diseases are correlated. In clinical practice, some chronic gastritis patients are also accompanied by intestinal inflammation. Due to the unclear pharmacological mechanism of MLD and its effect on intestinal inflammation, there is doubt whether MLD is still suitable for this type of patient. Therefore, this study aims to elucidate the pharmacological mechanism of MLD and identify its effect in the mouse model of intestinal inflammation. Materials and methodsMice intestinal inflammation model was induced by 2.5% dextran sulfate sodium (DSS). The mice were given different concentrations of MLD via oral gavage (0.25, 0.5 g/kg b.w.). Pharmacodynamic indicators were assessed including body weight, colon length, disease activity index (DAI), bloody stool score, inflammatory factors, histological change, etc. RAW264.7 macrophage cells were used for in vitro experiments that illuminated the role of MLD in reprogramming macrophage function and polarization. RT-qPCR and western blots were performed to measure the mRNA and protein levels of macrophage polarization marker and effector molecules. The functions of polarized macrophages were tested using ROS detection probes, Edu assay and wound healing assay. ResultsThe administration of MLD exhibited obvious hemostatic effects, while unexpectedly accentuating various aspects of the DSS-induced intestinal inflammation in mice, including increased body weight loss and colon shortening, elevated disease activity index, and intensified colonic tissue damage. Additionally, MLD treatment induced more severe inflammatory cell infiltration and higher proinflammatory cytokines expression in colon tissue. Further results showed that MLD promoted M1 macrophage polarization and stimulated its proinflammatory cytokines expression, while only slightly affecting the function of M2 macrophage. Western blot analysis revealed that MLD induced the phosphorylation of AKT and NF-κB. The polarization of M1 macrophages induced by MLD was inhibited by either an Akt inhibitor or a NF-κB inhibitor. ConclusionsAlthough MLD has an obvious hemostatic effect, it generally promoted the severity of DSS-induced colitis in mice by facilitating macrophage polarization toward the M1 phenotype through the AKT/NF-κB pathway. Our study suggested that MLD may not be suitable for colitis, especially during the acute inflammation stage.

Phlorizin Mitigates Dextran Sulfate Sodium-Induced Colitis in Mice by Modulating Gut Microbiota and Inhibiting Ferroptosis.

Phlorizin (PHZ) is the main active component of apple peel and presents a potential application value. In the past few years, some reports have suggested that PHZ may have antioxidant and anti-inflammatory effects. Herein, we have attempted to assess the protective effects of PHZ on dextran sodium sulfate (DSS)-induced colitis in mice and to determine the underlying molecular mechanisms. Our results suggested that early intervention with PHZ (20, 40, and 80 mg/kg) significantly reduced the severity of DSS-induced colitis in mice, as presented by a longer colon, improved tight junction protein, decreased disease activity index, and attenuated inflammatory factors. Additionally, early intervention with + (20, 40, and 80 mg/kg) significantly inhibited ferroptosis by decreasing the surrogate ferroptosis marker levels (MDA and Iron Content). Additionally, PHZ (80 mg/kg) increased the diversity of intestinal flora in colitic mice by elevating the levels of beneficial bacteria (Lactobacillaceae and Muribaculaceae) and reducing the levels of harmful bacteria (Lachnospiraceae). This indirectly led to an increase in the amount of short-chain fatty acids. A fecal microbial transplantation (FMT) test was conducted to show that PHZ (80 mg/kg) ameliorated ulcerative colitis (UC) by regulating gut dysbiosis. In conclusion, early intervention with PHZ decreased DSS-induced colitis in mice by preserving their intestinal barrier and regulating their intestinal flora.

VDUP1 Deficiency Promotes the Severity of DSS-Induced Colitis in Mice by Inducing Macrophage Infiltration.

The loss of vitamin D3 upregulated protein 1 (VDUP1) has been implicated in the pathogenesis of various inflammation-related diseases. Notably, reduced expression of VDUP1 has been observed in clinical specimens of ulcerative colitis (UC). However, the role of VDUP1 deficiency in colitis remains unclear. In this study, we investigated the role of VDUP1 in dextran sulfate sodium (DSS)-induced experimental colitis in mice. VDUP1-deficient mice were more susceptible to DSS-induced colitis than their wild-type (WT) littermates after 2% DSS administration. VDUP1-deficient mice exhibited an increased disease activity index (DAI) and histological scores, as well as significant colonic goblet cell loss and an increase in apoptotic cells. These changes were accompanied by a significant decrease in MUC2 mRNA expression and a marked increase in proinflammatory cytokines and chemokines within damaged tissues. Furthermore, phosphorylated NF-κB p65 expression was significantly upregulated in damaged tissues in the context of VDUP1 deficiency. VDUP1 deficiency also led to significant infiltration of macrophages into the site of ulceration. An in vitro chemotaxis assay confirmed that VDUP1 deficiency enhanced bone marrow-derived macrophage (BMDM) chemotaxis induced by CCL2. Overall, this study highlights VDUP1 as a regulator of UC pathogenesis and a potential target for the future development of therapeutic strategies.

Nd:YAG-photobiomodulation enhanced ADSCs multilineage differentiation and immunomodulation potentials

To investigate the effects of Nd: YAG (1064 nm) photobiomodulation on multilineage differentiation and immunomodulation potentials of adipose tissue-derived stem cells (ADSCs) in vitro and in vivo. For in vitro experiments, cells were divided into the control group (non-irradiated control ADSCs) and photobiomodulation groups. 0.5 J/cm2, 1 J/cm2, 2 J/cm2, and 4 J/cm2 were used for proliferation assays; for ADSCs adipogenic differentiation assays, 0.5 J/cm2, 1 J/cm2 were applied; 1 J/cm2 was used for migration and immunomodulation assays. The differentiation abilities were assessed by qPCR, Oil Red O staining, and Alizarin Red staining. The immunomodulation potential was assessed by qPCR and human cytokine array. DSS-induced colitis model. was used to test the effect of photobiomodulation on ADSCs immunomodulation potentials in vivo. Nd:YAG-based photobiomodulation dose-dependently promoted ADSCs proliferation and migration; 1 J/cm2 showed the best promotion effect on proliferation. Moreover, Nd:YAG photobiomodulation promoted ADSCs osteogenic differentiation and brown adipose adipogenic differentiation. The potential immunomodulation assays showed Nd:YAG photobiomodulation improved Anti-inflammation capacity of ADSCs and photobiomodulation irradiated ADSCs effectively alleviated DSS-induced colitis severity in vivo. Our study suggests Nd:YAG photobiomodulation might enhance the ADSCs multilineage differentiation and immunomodulation potentials. These results might help to enhance ADSCs therapeutic effects for clinical application. However, further studies are needed to explore the mechanisms of Nd:YAG photobiomodulation promoting multilineage differentiation and immunomodulation potentials of ADSCs.

Oral intake of titanium dioxide nanoparticles affect the course and prognosis of ulcerative colitis in mice: involvement of the ROS-TXNIP-NLRP3 inflammasome pathway

BackgroundTitanium dioxide (TiO2), no matter in nanoscale or micron sizes, has been widely used in food industry as additives for decades. Given the potential impact of TiO2 on the gastrointestinal epithelial and parenchymal cells, including goblet cells, the public consumers may suffer the risk of diseases caused by its widespread dissemination in food products. We therefore set out to investigate the impact of TiO2 NPs on the course and prognosis of ulcerative colitis by oral gavaging TiO2 NPs at the doses levels of 0, 30, 100, and 300 mg/kg during the induction (7 days, from day 1 to day 7) and recovery (10 days, from day 8 to day 17) phases of colitis in mice.ResultsThe ulcerative colitis (UC) disease model was established by administrating of 2.5% dextran sulfate sodium (DSS) solution. Our results show that TiO2 NPs significantly enhanced the severity of DSS-induced colitis, decreased the body weight, increased the disease activity index (DAI) and colonic mucosa damage index (CMDI) scores, shortened the colonic length, increased the inflammatory infiltration in the colon. The most significant changes occurred in the low dose (30 mg/kg) group of TiO2 NPs exposure during the development phase of UC and the high dose (300 mg/kg) group of TiO2 NPs during UC self-healing phase. Increased reactive oxygen species (ROS) level and upregulation of anti-oxidant enzymes including total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX) and catalase (CAT), demonstrate that the TiO2 NP exposure has triggered oxidative stress in mice. Moreover, the upregulation of caspase-1 mRNA and increased expression of thioredoxin interacting protein (TXNIP) further demonstrate the involvement of the ROS-TXNIP-NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway in aggravating the development of UC.ConclusionOral intake of TiO2 NPs could affect the course of acute colitis in exacerbating the development of UC, prolonging the UC course and inhibiting UC recovery.Graphical

Socs3 expression in myeloid cells modulates the pathogenesis of dextran sulfate sodium (DSS)-induced colitis.

Myeloid cells play a critical role in the pathogenesis of Inflammatory Bowel Diseases (IBDs), including Ulcerative Colitis (UC) and Crohn's Disease (CD). Dysregulation of the JAK/STAT pathway is associated with many pathological conditions, including IBD. Suppressors Of Cytokine Signaling (SOCS) are a family of proteins that negatively regulate the JAK/STAT pathway. Our previous studies identified that mice lacking Socs3 in myeloid cells developed a hyper-activated phenotype of macrophages and neutrophils in a pre-clinical model of Multiple Sclerosis. To better understand the function of myeloid cell Socs3 in the pathogenesis of colitis, mice with Socs3 deletion in myeloid cells (Socs3 ΔLysM) were utilized in a DSS-induced colitis model. Our results indicate that Socs3 deficiency in myeloid cells leads to more severe colitis induced by DSS, which correlates with increased infiltration of monocytes and neutrophils in the colon and increased numbers of monocytes and neutrophils in the spleen. Furthermore, our results demonstrate that the expression of genes related to the pathogenesis and diagnosis of colitis such as Il1β, Lcn2, S100a8 and S100a9 were specifically enhanced in Socs3-deficient neutrophils localized to the colon and spleen. Conversely, there were no observable differences in gene expression in Ly6C+ monocytes. Depletion of neutrophils using a neutralizing antibody to Ly6G significantly improved the disease severity of DSS-induced colitis in Socs3-deficient mice. Thus, our results suggest that deficiency of Socs3 in myeloid cells exacerbates DSS-induced colitis and that Socs3 prevents overt activation of the immune system in IBD. This study may provide novel therapeutic strategies to IBD patients with hyperactivated neutrophils.

Evaluation of microbial and vancomycin treatments in ulcerative colitis in murine models.

Despite the number of available therapies for ulcerative colitis (UC), severe side effects and high cost has limited their clinical application. Thus, finding new alternative strategies with minimal side effects is inevitable. Therefore, this study aimed to compare the effectiveness of different therapeutic approaches in DSS-induced colitis. Firstly, we designed oral bio-therapeutic products, Live Bacterial Products (LBP), which include a mixture of fecal bacteria strains isolated from healthy mice and prepared by microencapsulation and freeze-dried techniques. Then we investigated the efficiency of 7 days of freeze-dried FMT, LBP, and vancomycin treatments in DSS-induced colitis. Secondly, we compared the effect of 15 days of microbial therapies (freeze-dried powder of FMT and LBP microcapsules) and seven days of oral vancomycin on the severity of colitis in mice. Furthermore, the levels of IL-1β and TNF-α were measured in serum by ELISA, and the fecal microbiota diversity was analyzed by high-throughput sequencing for all mice groups. After seven days of treatments, our results indicated that oral vancomycin reduced the severity of DSS-induced colitis in mice, where weight gain and a decrease in IL-1 β and TNF-α levels were observed in the vancomycin group compared with other treatment groups. While after two weeks of treatment, the LBP microcapsules were able to reduce the severity of colitis. And at the end of the treatment period, weight gain and a decrease in the DAI scores and the levels of IL-1β and TNF-α were noted in the LBP treatment group compared to other treatment groups. By high-throughput sequencing of the 16S rRNA gene, our results showed that while the microcapsules LBP treatment increased the fecal microbial diversity, after vancomycin therapy, most of the fecal microbiota genera and operational taxonomic units (OTUs) were depleted. Our results concluded that treatment duration and preparation methods affect the microbial therapies' efficiency in UC. Furthermore, this study highlighted the negative consequences of oral vancomycin administration on gut health that should be known before using this medication.

Mesenchymal Stem Cells Ameliorate DSS-Induced Experimental Colitis by Modulating the Gut Microbiota and MUC-1 Pathway.

Mesenchymal stem cells (MSCs) have become novel therapeutic agents for the treatment of inflammatory bowel diseases (IBDs). However, the precise cellular and molecular mechanisms by which MSCs restore intestinal tissue homeostasis and repair the epithelial barrier have not been well elucidated. This study aimed to investigate the therapeutic effects and possible mechanisms of human MSCs in the treatment of experimental colitis. We performed an integrative transcriptomic, proteomic, untargeted metabolomics, and gut microbiota analyses in a dextran sulfate sodium (DSS)-induced IBD mouse model. The cell viability of IEC-6 cells was determined by Cell Counting Kit-8 (CCK-8) assay. The expression of MUC-1 and ferroptosis-related genes were determined by immunohistochemical staining, Western blot, and real-time quantitative polymerase chain reaction (RT-qPCR). Mice treated with MSCs showed notable amelioration in the severity of DSS-induced colitis, which was associated with reduced levels of proinflammatory cytokines and restoration of the lymphocyte subpopulation balance. Treatment with MSC restored the gut microbiota and altered their metabolites in DSS-induced IBD mice. The 16s rDNA sequencing showed that treatment with MSC modulated the composition of probiotics, including the upregulation of the contents of Firmicutes, Lactobacillus, Blautia, Clostridia, and Helicobacter bacteria in mouse colons. Protein proteomics and transcriptome analyses revealed that pathways related to cell immune responses, including inflammatory cytokines, were suppressed in the MSC group. The ferroptosis-related gene, MUC-1, was significantly upregulated in the MSC-treated group. MUC-1-inhibition experiments indicated that MUC-1 was essential for epithelial cell growth. Through overexpression of MUC-1, it showed that upregulation of SLC7A11 and GPX4, and downregulation of ACSL4 in erastin and RSL3-treated IEC-6 cells, respectively. This study described a mechanism by which treatment with MSCs ameliorated the severity of DSS-induced colitis by modulating the gut microbiota, immune response, and the MUC-1 pathway.

Colonization with ubiquitous protist Blastocystis ST1 ameliorates DSS-induced colitis and promotes beneficial microbiota and immune outcomes

Blastocystis is a species complex that exhibits extensive genetic diversity, evidenced by its classification into several genetically distinct subtypes (ST). Although several studies have shown the relationships between a specific subtype and gut microbiota, there is no study to show the effect of the ubiquitous Blastocystis ST1 on the gut microbiota and host health. Here, we show that Blastocystis ST1 colonization increased the proportion of beneficial bacteria Alloprevotella and Akkermansia, and induced Th2 and Treg cell responses in normal healthy mice. ST1-colonized mice showed decreases in the severity of DSS-induced colitis when compared to non-colonized mice. Furthermore, mice transplanted with ST1-altered gut microbiota were refractory to dextran sulfate sodium (DSS)-induced colitis via induction of Treg cells and elevated short-chain fat acid (SCFA) production. Our results suggest that colonization with Blastocystis ST1, one of the most common subtypes in humans, exerts beneficial effects on host health through modulating the gut microbiota and adaptive immune responses.

Intestinal epithelial cell-specific deletion of cytokine-inducible SH2- containing protein alleviates experimental colitis in ageing mice.

The incidence of inflammatory bowel disease (IBD) in the elderly has increased in recent years. However, the mechanisms underlying the ageing-related IBD susceptibility remain elusive. Cytokine-inducible SH2-containing protein (CISH) involved in regulating metabolism, the expansion of intestinal tuft cells and type-2 innate lymphoid cells, and ageing-related airway inflammation. Here, we investigated the role of CISH in ageing-related colitis susceptibility. CISH and phosphorylated signal transducer and activator of transcription-3 (p-STAT3) levels were evaluated in the colons of ageing mice and older ulcerative colitis (UC) patients. Mice with intestinal epithelial cell-specific knockout of Cish (CishΔIEC) and Cish-floxed mice were administered dextran sodium sulfate (DSS) or trinitrobenzene sulfonic acid (TNBS) to induce colitis. Colonic tissues were analysed in quantitative real-time polymerase chain reaction, immunoblotting, immunohistochemical, and histological staining experiments. Differentially expressed genes from colonic epithelia were analysed by RNA-sequencing. Ageing increased the severity of DSS-induced colitis and the expression of colonic epithelial CISH in mice. CishΔIEC prevented against the DSS or TNBS-induced colitis in middle-aged mice but not, in the young mice. RNA-sequencing analysis revealed that CishΔIEC significantly suppressed DSS-induced oxidative stress and proinflammatory responses. During ageing CCD841 cell model, knockdown of CISH decreased ageing-induced oxidative stress and proinflammatory responses, whereas these effects were compromised by knocking down or inhibiting STAT3. The increase in CISH expression was higher in the colonic mucosa of older patients with UC than that in healthy controls. CISH might be a proinflammatory regulator in ageing; therefore, targeted therapy against CISH may provide a novel strategy for treating ageing-related IBD.

Interleukin 17 B regulates colonic myeloid cell infiltration in a mouse model of DSS-induced colitis.

Cytokines play vital roles in the pathogenesis of inflammatory bowel disease. IL17B is protective in the development of colitis. However, how IL17B regulates intestinal inflammation and what cells are regulated by IL17B is still unknown. Here, we aimed to illustrate the IL17B dependent cellular and molecular changes in colon tissue in a mouse colitis model. The results showed that IL17B expression in colon tissues was elevated in inflamed tissues than non-inflamed tissues of IBD patients. Wild type (WT) and Il17b deficient (Il17b -/-) mice were given 2.5% dextran sodium sulfate (DSS) water, and in some case, Il17b -/- mice were treated with recombinant mouse IL17B. IL17B deficiency resulted in severe DSS-induced colitis with exaggerated weight loss, shorter colon length, and elevated proinflammatory cytokines in colon. Reconstitution of Il17b -/- mice with recombinant IL17B alleviated the severity of DSS-induced colitis. Single cell transcriptional analyses of CD45+ immune cells in colonic lamina propria revealed that loss of IL17B resulted in an increased neutrophil infiltration and enhanced inflammatory cytokines in intestinal macrophages in colitis, which were confirmed by real-time PCR and flow cytometry. IL17B treatment also inhibited lipopolysaccharide-induced inflammation in bone marrow-derived macrophages and mice. IL17B inhibits colitis by regulating colonic myeloid cell response. It might represent a novel potential therapeutic approach to treat the colitis.