Search

ObjectiveInflammatory bowel disease (IBD) is a multifactorial condition driven by genetic and environmental risk factors. A genetic variation in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene has been associated with autoimmune disorders while protecting from the IBD subtype Crohn’s disease. Mice expressing the murine orthologous PTPN22-R619W variant are protected from intestinal inflammation in the model of acute dextran sodium sulfate (DSS)-induced colitis. We previously identified food-grade titanium dioxide (TiO2, E171) as a neglected IBD risk factor. Here, we investigate the interplay of the PTPN22 variant and TiO2-mediated effects during IBD pathogenesis.DesignAcute DSS colitis was induced in wild-type and PTPN22 variant mice (PTPN22-R619W) and animals were treated with TiO2nanoparticles during colitis induction. Disease-triggering mechanisms were investigated using bulk and single-cell RNA sequencing.ResultsIn mice, administration of TiO2nanoparticles abrogated the protective effect of the variant, rendering PTPN22-R619W mice susceptible to DSS colitis. In early disease, cytotoxic CD8+T-cells were found to be reduced in the lamina propria of PTPN22-R619W mice, an effect reversed by TiO2administration. Normalisation of T-cell populations correlated with increasedIfngexpression and, at a later stage of disease, the promoted prevalence of proinflammatory macrophages that triggered severe intestinal inflammation.ConclusionOur findings indicate that the consumption of TiO2nanoparticles might have adverse effects on the gastrointestinal health of individuals carrying the PTPN22 variant. This demonstrates that environmental factors interact with genetic risk variants and can reverse a protective mechanism into a disease-promoting effect.

Background and Aims Exacerbated immune activation, intestinal dysbiosis and a disrupted intestinal barrier are common features among inflammatory bowel disease [IBD] patients. The polyamine spermidine, which is naturally present in all living organisms, is an integral component of the human diet, and exerts beneficial effects in human diseases. Here, we investigated whether spermidine treatment ameliorates intestinal inflammation and offers therapeutic potential for IBD treatment. Methods We assessed the effect of oral spermidine administration on colitis severity in the T cell transfer colitis model in Rag2−/− mice by endoscopy, histology and analysis of markers of molecular inflammation. The effects on the intestinal microbiome were determined by 16S rDNA sequencing of mouse faeces. The impact on intestinal barrier integrity was evaluated in co-cultures of patient-derived macrophages with intestinal epithelial cells. Results Spermidine administration protected mice from intestinal inflammation in a dose-dependent manner. While T helper cell subsets remained unaffected, spermidine promoted anti-inflammatory macrophages and prevented the microbiome shift from Firmicutes and Bacteroides to Proteobacteria, maintaining a healthy gut microbiome. Consistent with spermidine as a potent activator of the anti-inflammatory molecule protein tyrosine phosphatase non-receptor type 2 [PTPN2], its colitis-protective effect was dependent on PTPN2 in intestinal epithelial cells and in myeloid cells. The loss of PTPN2 in epithelial and myeloid cells, but not in T cells, abrogated the barrier-protective, anti-inflammatory effect of spermidine and prevented the anti-inflammatory polarization of macrophages. Conclusion Spermidine reduces intestinal inflammation by promoting anti-inflammatory macrophages, maintaining a healthy microbiome and preserving epithelial barrier integrity in a PTPN2-dependent manner.

Background and aims A single nucleotide polymorphism in protein tyrosine phosphatase non-receptor type 22 [PTPN22] has been associated with the onset of autoimmune disorders, but protects from Crohn’s disease. PTPN22 deficiency in mice promotes intestinal inflammation by modulating lymphocyte function. However, the impact of myeloid PTPN22 in colitis development remains unclear. The aim of this study was to investigate the role of PTPN2 in the IL-10 and the T cell transfer colitis models. Methods PTPN22-deficient mice were crossed with IL-10-/- and RAG2-/- mice. Naïve T cells were injected in RAG-/- mice to induce T-cell transfer colitis. Spontaneous colitis in IL-10-/- mice was monitored for up to 200 days. Results Here, we demonstrate that PTPN22 in non-lymphoid immune cells is required to protect against T cell transfer-mediated and IL-10 knock-out colitis. Analysis of the intestinal immune landscape demonstrated a marked reduction of granulocyte influx into the inflamed colon in PTPN22-deficient mice. On a molecular level, granulocytes were not only reduced by numbers, but also revealed a defective function. In particular, granulocyte activation and granulocyte-mediated bacteria killing was impaired upon loss of PTPN22, resulting in elevated bacterial burden and translocation beyond the intestinal epithelial barrier in PTPN22-deficient mice. Consistently, antibiotic-induced depletion of bacteria reverted the increased colitis susceptibility in PTPN22-deficient mice, whereas granulocyte depletion induced acolitis phenotype in wild-type mice similar to that observed in PTPN22-deficient mice. Conclusions In conclusion, our data demonstrate that PTPN22 is essential for adequate granulocyte activation and antimicrobial defence to protect the inflamed intestine from bacterial invasion and exacerbated colitis.

Plastic pollution is a major global challenge of our times, baring a potential threat for the environment and the human health. The increasing abundance of nanoplastic (NP) and microplastic (MP) particles in the human diet might negatively affect human health since they - particularly in patients suffering from inflammatory bowel disease (IBD) - might surpass the intestinal barrier. To investigate whether ingested plastic particles cross the intestinal epithelium and promote bowel inflammation, mice were supplemented with NP or MP polystyrene (PS) particles for 24 or 12 weeks before inducing acute or chronic dextran sodium sulfate (DSS) colitis with continuous plastic administration. Although ingested PS particles accumulated in the small intestine and organs distant from the gastrointestinal tract, PS ingestion did not affect intestinal health nor did it promote colitis severity. Although the lack of colitis-promoting effects of small PS particles might be a relief for IBD patients, potential accumulative effects of ingested plastic particles on the gastrointestinal health cannot be excluded.

Application of dextran sodium sulfate (DSS) is often used to induce experimental colitis. Current state of the art is to refrain from the use of analgesics due to their possible interaction with the model. However, the use of analgesics would be beneficial to reduce the overall constraint imposed on the animals. Here, we analyzed the effect of the analgesics Dafalgan (paracetamol), Tramal (tramadol) and Novalgin (metamizole) on DSS-induced colitis. To study the effect of those analgesics in colitis mouse models, acute and chronic colitis was induced in female C57BL6 mice by DSS administration in the drinking water. Analgesics were added to the drinking water on days four to seven (acute colitis) or on days six to nine of each DSS cycle (chronic colitis). Tramadol and paracetamol had minor effects on colitis severity. Tramadol reduced water uptake and activity levels slightly, while mice receiving paracetamol presented with a better overall appearance. Metamizole, however, significantly reduced water uptake, resulting in pronounced weight loss. In conclusion, our experiments show that tramadol and paracetamol are viable options for the use in DSS-induced colitis models. However, paracetamol seems to be slightly more favorable since it promoted the overall wellbeing of the animals upon DSS administration without interfering with typical readouts of colitis severity.

Inflammatory bowel disease (IBD) is a multifactorial condition driven by genetic and environmental risk factors. A genetic variation in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene has been associated with autoimmune disorders while protecting from the IBD subtype Crohn's disease. Mice expressing the murine orthologous PTPN22-R619W variant are protected from intestinal inflammation in the model of acute dextran sodium sulfate (DSS)-induced colitis. We previously identified food-grade titanium dioxide (TiOAcute DSS colitis was induced in wild-type and PTPN22 variant mice (PTPN22-R619W) and animals were treated with TiOIn mice, administration of TiOOur findings indicate that the consumption of TiO

Protein tyrosine phosphatase nonreceptor type 2 (PTPN2) plays a critical role in the pathogenesis of inflammatory bowel diseases (IBD). Mice lacking PTPN2 in dendritic cells (DCs) develop skin and liver inflammation by the age of 22 weeks due to a generalized loss of tolerance leading to uncontrolled immune responses. The effect of DC-specific PTPN2 loss on intestinal health, however, is unknown. The aim of this study was to investigate the DC-specific role of PTPN2 in the intestine during colitis development. PTPN2fl/flxCD11cCre mice were subjected to acute and chronic DSS colitis as well as T cell transfer colitis. Lamina propria immune cell populations were analyzed using flow cytometry. DC-specific PTPN2 deletion promoted infiltration of B and T lymphocytes, macrophages, and DCs into the lamina propria of unchallenged mice and elevated Th1 abundance during acute DSS colitis, suggesting an important role for PTPN2 in DCs in maintaining intestinal immune cell homeostasis. Surprisingly, those immune cell alterations did not translate into increased colitis susceptibility in acute and chronic DSS-induced colitis or T cell transfer colitis models. However, macrophage depletion by clodronate caused enhanced colitis severity in mice with a DC-specific loss of PTPN2. Loss of PTPN2 in DCs affects the composition of lamina propria lymphocytes, resulting in increased infiltration of innate and adaptive immune cells. However, this did not result in an elevated colitis phenotype, likely because increased infiltration of macrophages in the intestine upon loss of PTPN2 loss in DCs can compensate for the inflammatory effect of PTPN2-deficient DCs.

Background Fistulas represent a frequent and severe complication in patients with Crohn disease (CD). Tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta, and interleukin (IL)-13 are known to trigger epithelial-mesenchymal transition (EMT), promoting fistula formation. Here, we investigated the role of T-lymphocytes (T cells) in fistula pathogenesis. Methods CD3+CD8-, CD3+CD8+, or CD45+CD3- cells from healthy volunteers, patients with CD, and patients with CD with perianal fistula were co-cultured with HT-29 cells. The EMT, cytokine production, and mRNA expression were analyzed. Perianal CD fistula specimens were immunohistochemically stained for cytokines and their receptors. The effect of cytokines on EMT induction was investigated using an EMT spheroid model. Results Patients with CD with fistula revealed more CD3+CD8- and less CD3+CD8+ T cells in blood than healthy control patients and patients with CD without fistula. In perianal fistula specimens, CD4+ cells—and to a lesser extent CD8+ cells—were highly present around fistula tracts. When co-cultured with HT-29 cells, both cell subsets promoted EMT-related gene expression and TNF-α production in a time-dependent manner. The CD3+CD8- T cells from patients with CD with fistula also produced higher amounts of IL-13 than cells from healthy control patients or patients with CD without a fistula. We found that IL-22 and IL-22Rα1 were highly expressed in perianal CD fistula specimens and that IL-22 cotreatment potentiated TNF-α-induced EMT in HT-29 spheroids. Conclusions Our data indicate that both CD3+CD8- and CD3+CD8+ T cells play an important role in the pathogenesis of perianal CD fistulas by the secretion of TNF-α. Our data support clinical evidence indicating that anti-TNF-α therapy is effective in fistula treatment and identify IL-13 and IL-22 as possible novel therapeutic targets for fistula therapy.

Environmental and genetic factors have been demonstrated to contribute to the development of inflammatory bowel disease (IBD). Recent studies suggested that the food additive, titanium dioxide (TiO2) might play a causative role in the disease. Therefore, in the present study we aimed to explore the interaction between the food additive TiO2 and the well-characterized IBD risk gene protein tyrosine phosphatase non-receptor type 2 (Ptpn2) and their role in the development of intestinal inflammation. Dextran sodium sulphate (DSS)-induced acute colitis was performed in mice lacking the expression of Ptpn2 in myeloid cells (Ptpn2LysMCre) or their wild type littermates (Ptpn2fl/fl) and exposed to the microparticle TiO2. The impact of Ptpn2 on TiO2 signalling pathways and TiO2-induced IL-1&beta, and IL-10 levels were studied using bone marrow-derived macrophages (BMDMs). Ptpn2LysMCre exposed to TiO2 exhibited more severe intestinal inflammation than their wild type counterparts. This effect was likely due to the impact of TiO2 on the differentiation of intestinal macrophages, suppressing the number of anti-inflammatory macrophages in Ptpn2 deficient mice. Moreover, we also found that TiO2 was able to induce the secretion of IL-1&beta, via mitogen-activated proteins kinases (MAPKs) and to repress the expression of IL-10 in bone marrow-derived macrophages via MAPK-independent pathways. This is the first evidence of the cooperation between the genetic risk factor Ptpn2 and the environmental factor TiO2 in the regulation of intestinal inflammation. The results presented here suggest that the ingestion of certain industrial compounds should be taken into account, especially in individuals with increased genetic risk

BackgroundThe rise in the prevalence of inflammatory bowel diseases in the past decades coincides with changes in nutritional habits, such as adaptation of a Western diet. However, it is largely unknown how certain nutritional habits, such as energy drink consumption, affect intestinal inflammation. Here, we assessed the effect of energy drink supplementation on the development of intestinal inflammation in vitro and in vivo.MethodsHT-29 and T84 intestinal epithelial cells and THP-1 monocytic cells were treated with IFNγ in presence or absence of different concentrations of an energy drink. Colitis was induced in C57BL/6 mice by addition of dextran sodium sulfate (DSS) to drinking water with or without supplementation of the energy drink.ResultsEnergy drink supplementation caused a dose-dependent decrease in IFNγ-induced epithelial barrier permeability, which was accompanied by upregulation of the pore-forming protein claudin-2. Administration of the energy drink reduced secretion of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-α from HT-29, T84, and THP-1 cells. In vivo, energy drink administration reduced clinical symptoms of DSS-induced colitis and epithelial barrier permeability. Endoscopic and histologic colitis scores and expression of pro-inflammatory cytokines were significantly reduced by energy drink co-administration.ConclusionEnergy drink consumption seems to exert an unexpected anti-inflammatory effect in vitro and in vivo in our experimental setting. However, our experimental approach focuses on intestinal inflammation and neglects additional effects of energy drink consumption on the body (eg, on metabolism or sleep). Therefore, the translation of our findings into the human situation must be taken with caution.

Background The single nucleotide polymorphism (SNP) rs1893217 within the gene locus encoding PTPN2 represents a risk factor for inflammatory bowel disease (IBD). Our previous work demonstrated reduced PTPN2 activity and subsequently increased inflammatory signaling upon presence of SNP rs1893217. The naturally occurring polyamine spermidine reduces pro-inflammatory signaling via induction of PTPN2 activity; however, the effect of SNP rs1893217 on the anti-inflammatory potential of spermidine is still unknown. Here, we investigated how presence of SNP rs1893217 affects treatment efficacy of spermidine and whether it might serve as a potential biomarker for spermidine treatment. Methods Human T84 (wild-type [WT] for PTPN2 SNP rs1893217) and HT29 (heterozygous for PTPN2 SNP rs1893217) intestinal epithelial cells (IECs) were treated with several polyamines from the putrescine-spermidine pathway. T84 and HT29 IECs, THP-1 monocytes (WT and transfected with a lentiviral vector expressing PTPN2 SNP rs1893217) and genotyped, patient-derived peripheral blood mononuclear cells were challenged with IFN-γ and/or spermidine. Results Among the analyzed polyamines, spermidine was the most efficient activator of PTPN2 phosphatase activity, regardless of the PTPN2 genotype. Spermidine suppressed IFN-γ-induced STAT1 and STAT3 phosphorylation, along with decreased mRNA expression of ICAM-1, NOD2, and IFNG in IECs and monocytes. Of note, these effects were clearly more pronounced when the disease-associated PTPN2 C-variant in SNP rs1893217 was present. Conclusions Our data demonstrate that spermidine is the most potent polyamine in the putrescine-spermine axis for inducing PTPN2 enzymatic activity. The anti-inflammatory effect of spermidine is potentiated in the presence of SNP rs1893217, and this SNP might thus be a useful biomarker for possible spermidine-treatment in IBD patients.

Background Inflammatory bowel disease (IBD) is caused by a complex interaction among genetic, immunological, bacterial and environmental factors. In this scenario, protein tyrosine phosphatase non-receptor type-2 (PTPN2) has been recognised as a risk factor for the development of IBD and functional studies revealed a major role for this protein in the development of experimental colitis through the regulation of the inflammasome, among other processes. In the same way, a potential relationship between diet components and IBD was suggested. In fact, it was reported that the food additive titanium dioxide (TiO2) was able to induce inflammasome activation in vitro and increase colitis severity in vivo. These observations led us to hypothesise a putative relationship between PTPN2 and TiO2 that could explain the effects of this microparticle in the pathogenesis of bowel inflammation. Methods DSS colitis model was performed in mice lacking PTPN2 in myeloid cells and their wild-type littermates, treated or not with titanium dioxide. After that, histology studies, flow cytometry, expression analysis, ELISA and barrier function experiments were performed. Also, bone marrow-derived macrophages (BMDMs) were used for in vitro studies. Results Titanium dioxide was able to exacerbate DSS-induced colitis, especially in mice lacking PTPN2 in myeloid cells. Flow cytometry analysis of the lamina propria revealed significant changes in different immune cell populations such as macrophages. In vitro experiments using BMDMs revealed that TiO2 induced the activation of the inflammasome. Also, this microparticle down-regulated the expression of the anti-inflammatory cytokine IL-10 and these effects were mainly mediated by JNK and ERK kinases. Conclusions The food additive titanium dioxide seems to play a negative role in colitis development by affecting the production of pro- and anti-inflammatory mediators in macrophages. This study reveals a new mechanism by which a certain component of the diet modulates intestinal inflammation.