In vivo imaging of reactive oxygen and nitrogen species in murine colitis

Dysregulated NOX1-NOS2 activity as hallmark of ileitis in mice

Inflammation of the ileum, or ileitis, is commonly caused by Crohn's disease (CD) but can also accompany ulcerative colitis (backwash ileitis), infections or drug-related damage. Oxidative tissue injury triggered by reactive oxygen species (ROS) is considered part of the ileitis etiology. However, not only elevated ROS but also permanently decreased ROS are associated with inflammatory bowel disease (IBD). While very early onset IBD (VEO-IBD) is associated with a spectrum of NOX1 variants, how NOX1 inactivation contributes to disease development remains ill-defined. Besides propagating signaling responses, NOX1 provides superoxide for peroxynitrite formation in the epithelial barrier. Here we report that NOX4, an H2O2-generating NADPH oxidase with documented tissue protective effects in the intestine and other tissues, limits the generation of ileal peroxynitrite by NOX1/NOS2. Deletion of NOX4 leads to persistent peroxynitrite excess, hyperpermeability, villus blunting, muscular hypertrophy, chemokine/cytokine upregulation and dysbiosis. Conversely, SAMP1/YitFc mice, a CD-like ileitis model, showed age-dependent NOX1/NOS2 downregulation preventing ileal peroxynitrite formation in homeostasis and LPS-induced acute inflammation. Deficiency in NOX1 correlated with the upregulation of antimicrobial peptides, suggesting that ileal peroxynitrite acts as chemical barrier and microbiota modifier in the ileum.

Detection of Intestinal Inflammation by Vascular Adhesion Protein-1-Targeted [68Ga]Ga-DOTA-Siglec-9 Positron Emission Tomography in Murine Models of Inflammatory Bowel Disease

PURPOSE

Inflammatory bowel disease (IBD) can be imaged with positron emission tomography (PET), but existing PET radiopharmaceuticals have limited diagnostic accuracy. Vascular adhesion protein-1 (VAP-1) is an endothelial cell surface molecule that controls leukocyte extravasation into sites of inflammation. However, the role of inflammation-induced VAP-1 expression in IBD is still unclear. Therefore, this study investigated the utility of VAP-1-targeted [68Ga]Ga-DOTA-Siglec-9 positron emission tomography/computed tomography (PET/CT) for assessing inflammation in two mouse models of IBD.

PROCEDURES

Studies were performed using K8-/- mice that develop a chronic colitis-phenotype and C57Bl/6NCrl mice with acute intestinal inflammation chemically-induced using 2.5% dextran sodium sulfate (DSS) in drinking water. In both diseased and control mice, uptake of the VAP-1-targeting peptide [68Ga]Ga-DOTA-Siglec-9 was assessed in intestinal regions of interest using in vivo PET/CT, after which ex vivo gamma counting, digital autoradiography, and histopathological analyses were performed. Immunofluorescence staining was performed to determine VAP-1-expression in the intestine, including in samples from patients with ulcerative colitis.

RESULTS

Intestinal inflammation could be visualized by [68Ga]Ga-DOTA-Siglec-9 PET/CT in two murine models of IBD. In both models, the in vivo PET/CT and ex vivo studies of [68Ga]Ga-DOTA-Siglec-9 uptake were significantly higher than in control mice. The in vivo uptake was increased on average 1.4-fold in the DSS model and 2.0-fold in the K8-/- model. Immunofluorescence staining revealed strong expression of VAP-1 in the inflamed intestines of both mice and patients.

CONCLUSIONS

This study suggests that the VAP-1-targeting [68Ga]Ga-DOTA-Siglec-9 PET tracer is a promising tool for non-invasive imaging of intestinal inflammation. Future studies in patients with IBD and evaluation of the potential value of [68Ga]Ga-DOTA-Siglec-9 in diagnosis and monitoring of the disease are warranted.

Integrative Multiomics Profiling Unveils the Protective Function of Ulinastatin against Dextran Sulfate Sodium-Induced Colitis

Ulcerative colitis is an inflammatory bowel disease with multiple pathogeneses. Here, we aimed to study the therapeutic role of ulinastatin (UTI), an anti-inflammatory bioagent, and its associated mechanisms in treating colitis. Dextran sulfate sodium was administrated to induce colitis in mice, and a subgroup of colitis mice was treated with UTI. The gut barrier defect and inflammatory manifestations of colitis were determined via histological and molecular experiments. In addition, transcriptomics, metagenomics, and metabolomics were employed to explore the possible mechanisms underlying the effects of UTI. We found that UTI significantly alleviated the inflammatory manifestations and intestinal barrier damage in the mice with colitis. Transcriptome sequencing revealed a correlation between the UTI treatment and JAK-STAT signaling pathway. UTI up-regulated the expression of SOCS1, which subsequently inhibited the phosphorylation of JAK2 and STAT3, thus limiting the action of inflammatory mediators. In addition, 16S rRNA sequencing illustrated that UTI maintained a more stable intestinal flora, protecting the gut from dysbiosis in colitis. Moreover, metabolomics analysis demonstrated that UTI indeed facilitated the production of some bile acids and short-chain fatty acids, which supported intestinal homeostasis. Our data provide evidence that UTI is effective in treating colitis and support the potential use of UTI treatment for patients with ulcerative colitis.

VEO-IBD NOX1 variant highlights a structural region essential for NOX/DUOX catalytic activity

Inflammatory bowel diseases (IBD) are chronic intestinal disorders that result from an inappropriate inflammatory response to the microbiota in genetically susceptible individuals, often triggered by environmental stressors. Part of this response is the persistent inflammation and tissue injury associated with deficiency or excess of reactive oxygen species (ROS). The NADPH oxidase NOX1 is highly expressed in the intestinal epithelium, and inactivating NOX1 missense mutations are considered a risk factor for developing very early onset IBD. Albeit NOX1 has been linked to wound healing and host defence, many questions remain about its role in intestinal homeostasis and acute inflammatory conditions. Here, we used in vivo imaging in combination with inhibitor studies and germ-free conditions to conclusively identify NOX1 as essential superoxide generator for microbiota-dependent peroxynitrite production in homeostasis and during early endotoxemia. NOX1 loss-of-function variants cannot support peroxynitrite production, suggesting that the gut barrier is persistently weakened in these patients. One of the loss-of-function NOX1 variants, NOX1 p. Asn122His, features replacement of an asparagine residue located in a highly conserved HxxxHxxN motif. Modelling the NOX1-p22phox complex revealed near the distal heme an internal pocket restricted by His119 and Asn122 that is part of the oxygen reduction site. Functional studies in several human NADPH oxidases show that substitution of asparagine with amino acids with larger side chains is not tolerated, while smaller side chains can support catalytic activity. Thus, we identified a previously unrecognized structural feature required for the electron transfer mechanism in human NADPH oxidases.

Delivery of Lipid Nanoparticles with ROS Probes for Improved Visualization of Hepatocellular Carcinoma

Reactive oxygen species (ROS) are highly reactive products of the cell metabolism derived from oxygen molecules, and their abundant level is observed in many diseases, particularly tumors, such as hepatocellular carcinoma (HCC). In vivo imaging of ROS is a necessary tool in preclinical research to evaluate the efficacy of drugs with antioxidant activity and for diagnosis and monitoring of diseases. However, most known sensors cannot be used for in vivo experiments due to low stability in the blood and rapid elimination from the body. In this work, we focused on the development of an effective delivery system of fluorescent probes for intravital ROS visualization using the HCC model. We have synthesized various lipid nanoparticles (LNPs) loaded with ROS-inducible hydrocyanine pro-fluorescent dye or plasmid DNA (pDNA) with genetically encoded protein sensors of hydrogen peroxide (HyPer7). LNP with an average diameter of 110 ± 12 nm, characterized by increased stability and pDNA loading efficiency (64 ± 7%), demonstrated preferable accumulation in the liver compared to 170 nm LNPs. We evaluated cytotoxicity and demonstrated the efficacy of hydrocyanine-5 and HyPer7 formulated in LNP for ROS visualization in mouse hepatocytes (AML12 cells) and in the mouse xenograft model of HCC. Our results demonstrate that obtained LNP could be a valuable tool in preclinical research for visualization ROS in liver diseases.

Effect of ethyl gallate and propyl gallate on dextran sulfate sodium (DSS)-induced ulcerative colitis in C57BL/6 J mice: preventive and protective

OBJECTIVE AND DESIGN

Inflammatory bowel disease (IBD) is an idiopathic inflammatory condition of the digestive system marked by oxidative stress, leukocyte infiltration, and elevation of inflammatory mediators. In this study, we demonstrate the protective effect of ethyl gallate (EG), a phytochemical, and propyl gallate (PG), an anti-oxidant, given through normal drinking water (DW) and copper water (CW) in various combinations, which had a positive effect on the amelioration of DSS-induced ulcerative colitis in C57BL/6 J mice.

MATERIALS AND METHODS

We successfully determined the levels of proinflammatory cytokines and anti-oxidant enzymes by ELISA, tracked oxidative/nitrosative stress (RO/NS) by in vivo imaging (IVIS) using L-012 chemiluminescent probe, disease activity index (DAI), and histopathological and morphometric analysis of colon in DSS-induced colitis in a model.

RESULTS

The results revealed that oral administration of ethyl gallate and propyl gallate at a dose of 50 mg/kg considerably reduced the severity of colitis and improved both macroscopic and microscopic clinical symptoms. The level of proinflammatory cytokines (TNF-α, IL-6, IL-1β, and IFN-γ) in colonic tissue was considerably reduced in the DSS + EG-treated and DSS + PG-treated groups, compared to the DSS alone-treated group. IVIS imaging of animals from the DSS + EG and DSS + PG-treated groups showed a highly significant decrease in RO/NS species relative to the DSS control group, with the exception of the DSS + PG/CW and DSS + EG + PG/CW-treated groups. We also observed lower levels of myeloperoxidase (MPO), nitric oxide (NO), and lipid peroxidation (LPO), and restored levels of GST and superoxide dismutase (SOD) in DSS + EG-DW/CW, DSS + PG/DW, and DSS + EG + PG/DW groups compared to DSS alone-treated group. In addition, we showed that the EG, PG, and EG + PG treatment significantly reduced the DAI score, and counteracted the body weight loss and colon shortening in mice compared to DSS alone-treated group. In this 21-day study, mice were treated daily with test substances and were challenged to DSS from day-8 to 14.

CONCLUSION

Our study highlights the protective effect of ethyl gallate and propyl gallate in various combinations which, in pre-clinical animals, serve as an anti-inflammatory drug against the severe form of colitis, indicating its potential for the treatment of IBD in humans. In addition, propyl gallate was investigated for the first time in this study for its anti-colitogenic effect with normal drinking water and reduced effect with copper water.

Response Variability to Drug Testing in Two Models of Chemically Induced Colitis

The lack of knowledge regarding the pathogenesis of IBD is a challenge for the development of more effective and safer therapies. Although in vivo preclinical approaches are critical for drug testing, none of the existing models accurately reproduce human IBD. Factors that influence the intra-individual response to drugs have barely been described. With this in mind, our aim was to compare the anti-inflammatory efficacy of a new molecule (MTADV) to that of corticosteroids in TNBS and DSS-induced colitis mice of both sexes in order to clarify further the response mechanism involved and the variability between sexes. The drugs were administered preventively and therapeutically, and real-time bioluminescence was performed for the in vivo time-course colitis monitoring. Morphometric data were also collected, and colonic cytokines and acute plasma phase proteins were analyzed by qRT-PCR and ELISA, respectively-bioluminescence images correlated with inflammatory markers. In the TNBS model, dexamethasone worked better in females, while MTADV improved inflammation in males. In DSS-colitis, both therapies worked similarly. Based on the molecular profiles, interaction networks were constructed to pinpoint the drivers of therapeutic response that were highly dependent on the sex. In conclusion, our results suggest the importance of considering sex in IBD preclinical drug screening.

Sodium Butyrate Inhibits Oxidative Stress and NF-κB/NLRP3 Activation in Dextran Sulfate Sodium Salt-Induced Colitis in Mice with Involvement of the Nrf2 Signaling Pathway and Mitophagy

BACKGROUND

Sodium butyrate (NaB) is a short-chain fatty acid produced by intestinal microbial fermentation of dietary fiber, and has been shown to be effective in inhibiting ulcerative colitis (UC). However, how NaB regulates inflammation and oxidative stress in the pathogenesis of UC is not clear.

AIMS

The purpose of this study was to use a dextran sulfate sodium salt (DSS)-induced murine colitis model, and determine the effects of NaB and the related molecular mechanisms.

METHODS

Colitis model was induced in mice by administration of 2.5%(wt/vol) DSS. 0.1 M NaB in drinking water, or intraperitoneal injection of NaB (1 g/kg body weight) was given during the study period. In vivo imaging was performed to detect abdominal reactive oxygen species (ROS). Western blotting and RT-PCR were used to determine the levels of target signals.

RESULTS

The results showed that NaB decreases the severity of colitis as determined by an improved survival rate, colon length, spleen weight, disease activity index (DAI), and histopathological changes. NaB reduced oxidative stress as determined by a reduction in abdominal ROS chemiluminescence signaling, inhibition of the accumulation of myeloperoxidase and malondialdehyde, and restoration of glutathione activity. NaB activated the COX-2/Nrf2/HO-1 pathway by increasing the expressions of COX-2, Nrf2, and HO-1 proteins. NaB inhibited the phosphorylation of NF-κB and activation of NLRP3 inflammasomes, and reduced the secretion of corresponding inflammatory factors. Furthermore, NaB promoted the occurrence of mitophagy via activating the expression of Pink1/Parkin.

CONCLUSIONS

In conclusion, our results indicate that NaB improves colitis by inhibiting oxidative stress and NF-κB/NLRP3 activation, which may be via COX-2/Nrf2/HO-1 activation and mitophagy.

Vimentin Suppresses Inflammation and Tumorigenesis in the Mouse Intestine

Vimentin has been implicated in wound healing, inflammation, and cancer, but its functional contribution to intestinal diseases is poorly understood. To study how vimentin is involved during tissue injury and repair of simple epithelium, we induced colonic epithelial cell damage in the vimentin null (Vim^−/−) mouse model. Vim^−/− mice challenged with dextran sodium sulfate (DSS) had worse colitis manifestations than wild-type (WT) mice. Vim^−/− colons also produced more reactive oxygen and nitrogen species, possibly contributing to the pathogenesis of gut inflammation and tumorigenesis than in WT mice. We subsequently describe that CD11b⁺ macrophages served as the mainly cellular source of reactive oxygen species (ROS) production via vimentin-ROS-pSTAT3–interleukin-6 inflammatory pathways. Further, we demonstrated that Vim^−/− mice did not develop colitis-associated cancer model upon DSS treatment spontaneously but increased tumor numbers and size in the distal colon in the azoxymethane/DSS model comparing with WT mice. Thus, vimentin has a crucial role in protection from colitis induction and tumorigenesis of the colon.

Targeted deletion of keratin 8 in intestinal epithelial cells disrupts tissue integrity and predisposes to tumorigenesis in the colon

Keratin 8 (K8) is the main intestinal epithelial intermediate filament protein with proposed roles for colonic epithelial cell integrity. Here, we used mice lacking K8 in intestinal epithelial cells (floxed K8 and Villin-Cre1000 and Villin-CreERt2) to investigate the cell-specific roles of intestinal epithelial K8 for colonocyte function and pathologies. Intestinal epithelial K8 deletion decreased K8 partner proteins, K18-K20, 75-95%, and the remaining keratin filaments were located at the colonocyte apical regions with type II K7, which decreased 30%. 2-Deoxy-2-[18F]-fluoroglucose positron emission tomography in vivo imaging identified a metabolic phenotype in the lower gut of the conditional K8 knockouts. These mice developed intestinal barrier leakiness, mild diarrhea, and epithelial damage, especially in the proximal colon. Mice exhibited shifted differentiation from enterocytes to goblet cells, displayed longer crypts and an increased number of Ki67 + transit-amplifying cells in the colon. Significant proproliferative and regenerative signaling occurred in the IL-22, STAT3, and pRb pathways, with minor effects on inflammatory parameters, which, however, increased in aging mice. Importantly, colonocyte K8 deletion induced a dramatically increased sensitivity to azoxymethane-induced tumorigenesis. In conclusion, intestinal epithelial K8 plays a significant role in colonocyte epithelial integrity maintenance, proliferation regulation and tumor suppression.

Small-molecule fluorescent probes: big future for specific bacterial labeling and infection detection

Bacterial infections remain a global healthcare problem that is particularly attributed to the spread of antibiotic resistance and the evolving pathogenicity. Accurate and swift approaches for infection diagnosis are urgently needed to facilitate antibiotic stewardship and effective medical treatment. Direct optical imaging for specific bacterial labeling and infection detection offers an attractive prospect of precisely monitoring the infectious disease status and therapeutic response in real time. This feature article focuses on the recent advances of small-molecule probes developed for fluorescent imaging of bacteria and infection, which covers the probe design, responsive mechanisms and representative applications. In addition, the perspective and challenges to advance small-molecule fluorescent probes in the field of rapid drug-resistant bacterial detection and clinical diagnosis of bacterial infections are discussed. We envision that the continuous advancement and clinical translations of such a technique will have a strong impact on future anti-infective medicine.

NLRP3 protects mice from radiation-induced colon and skin damage via attenuating cGAS-STING signaling

In the present study, the effects of NLRP3 on radiation-induced tissue damage, including colon and skin damage in mice, and the possible mechanisms were explored in vivo and in vitro. The mice were subjected to whole abdomen radiation by timed exposure to X-ray at a cumulative dose of 14 Gy. The survival rate showed that NLRP3 deficiency increased the mortality rate in mice. Furthermore, colon damage, evaluated by H&E staining and barrier function analysis, were significantly aggravated by NLRP3 deficiency. Enhanced phosphorylation of p-TBK1 and p-IRF3 in colonic tissue as well as elevated IFN-β levels in the serum indicated hyperactivation of cGAS-STING signaling. Moreover, radiation-induced expression of p-TBK1, p-IRF3, and IFN-β in BMDMs increased in vitro after NLRP3 knockout. Thus, our study outcomes suggest that NLRP3 may protect mice from radiation-induced tissue damage via attenuating cGAS-STING signaling.

Improvement of magnesium isoglycyrrhizinate on DSS-induced acute and chronic colitis

Inflammatory bowel disease (IBD) is a worldwide prototypical complex disease, owing to its multifactorial causes, relapsing and remitting condition and high incidence. Thus, effective therapeutic approaches need to be developed for patients with IBD. Currently, we reported the improving effect of magnesium isoglycyrrhizinate on colitis induced by dextran sulfate sodium (DSS). We found that magnesium isoglycyrrhizinate treatment significantly alleviated DSS-induced acute and chronic colitis by inhibiting the inflammatory response characterized by reduce of the infiltrations of immune cell and the level of pro-inflammatory cytokines. Besides, magnesium isoglycyrrhizinate treatment significantly inhibited the level of ROS and decreased the gut barrier destruction after DSS treatment. Furthermore, the results also showed that administration of magnesium isoglycyrrhizinate significantly reduced the colonic fibrosis. Taken together, these results revealed the potency of magnesium isoglycyrrhizinate on the intestinal inflammation, by which points to the possible use of magnesium isoglycyrrhizinate for IBD therapy in clinical applications.

A novel danshensu derivative ameliorates experimental colitis by modulating NADPH oxidase 4-dependent NLRP3 inflammasome activation

We have previously reported a novel compound [4‐(2‐acetoxy‐3‐((R)‐3‐(benzylthio)‐1‐methoxy‐1‐oxopropan‐2‐ylamino)‐3‐oxopropyl)‐1,2‐phenylene diacetate (DSC)], derived from danshensu, exhibits cytoprotective activities in vitro. Here, we investigated the effects and underlying mechanisms of DSC on dextran sodium sulphate (DSS)‐induced experimental colitis. We found that DSC treatment afforded significant protection against the development of colitis, evidencing by suppressed inflammatory responses and enhanced barrier integrity. Intriguingly, DSC specifically down‐regulated DSS‐induced colonic NADPH oxidase 4 (Nox4) expression, accompanied by a balanced redox status, suppressed nuclear factor‐κB (NF‐κB) and NLRP3 inflammasome activation and up‐regulated nuclear factor (erythroid‐derived 2)‐like 2 and haeme oxygenase‐1 expression. In vitro study also demonstrated DSC also markedly decreased Nox4 expression and activity associated with inhibiting reactive oxygen species generation, NF‐κB activation and NLRP3 inflammasome activation in bone marrow‐derived macrophages. Either lentiviral Nox4 shRNA‐mediated Nox4 knockdown or Nox4‐specific small‐interfering RNA mimicked effects of DSC by suppressing NLPR3 inflammasome activation to alleviate experimental colitis or inflammatory macrophage response. Collectively, our results provide the first evidence that DSC ameliorates experimental colitis partly through modulating Nox4‐mediated NLRP3 inflammasome activation.

All-trans Retinoic Acid Counteracts Diarrhea and Inhibition of Downregulated in Adenoma Expression in Gut Inflammation

BACKGROUND

Intestinal epithelial apical membrane Cl-/HCO3- exchanger DRA (downregulated in adenoma, SLC26A3) has emerged as an important therapeutic target for diarrhea, emphasizing the potential therapeutic role of agents that upregulate DRA. All-trans retinoic acid (ATRA), a key vitamin A metabolite, was earlier shown by us to stimulate DRA expression in intestinal epithelial cells. However, its role in modulating DRA in gut inflammation has not been investigated.

AIMS

Our aim was to analyze the efficacy of ATRA in counteracting inflammation-induced decrease in DRA in vitro and in vivo.

METHODS

Interferon-γ (IFN-γ)-treated Caco-2 cells and dextran sulfate sodium (DSS)-treated C57BL/6J mice served as in vitro and in vivo models of gut inflammation, respectively. The effect of ATRA on IFN-γ-mediated inhibition of DRA function, expression, and promoter activity were elucidated. In the DSS colitis model, diarrheal phenotype, cytokine response, in vivo imaging, myeloperoxidase activity, and DRA expression were measured in the distal colon.

RESULTS

All-trans retinoic acid (10 μM, 24 h) abrogated IFN-γ (30 ng/mL, 24 h)-induced decrease in DRA function, expression, and promoter activity in Caco-2 cells. All-trans retinoic acid altered IFN-γ signaling via blocking IFN-γ-induced tyrosine phosphorylation of STAT-1. All-trans retinoic acid cotreatment (1 mg/kg BW, i.p. daily) of DSS-treated mice (3% in drinking water for 7 days) alleviated colitis-associated weight loss, diarrheal phenotype, and induction of IL-1β and CXCL1 and a decrease in DRA mRNA and protein levels in the colon.

CONCLUSION

Our data showing upregulation of DRA under normal and inflammatory conditions by ATRA demonstrate a novel role of this micronutrient in alleviating IBD-associated diarrhea.

Intraportally delivered stem cell spheroids localize in the liver and protect hepatocytes against GalN/LPS-induced fulminant hepatic toxicity

Background

Systemic inflammatory response syndrome (SIRS) is common in severe fulminant hepatic failure (FHF) and has a high mortality rate (20–50%) due to irreversible cerebral edema or sepsis. Stem cell-based treatment has emerged as a promising alternative therapeutic strategy to prolong the survival of patients suffering from FHF via the inhibition of SIRS due to their immunomodulatory effects.

Methods

3D spheroids of adipose-derived mesenchymal stem cells (3D-ADSC) were prepared by the hanging drop method. The efficacy of the 3D-ADSC to rescue FHF was evaluated in a d-galactosamine/lipopolysaccharide (GalN/LPS)-induced mouse model of FHF via intraportal transplantation of the spheroids.

Results

Intraportally delivered 3D-ADSC better engrafted and localized into the damaged livers compared to 2D-cultured adipose-derived mesenchymal stem cells (2D-ADSC). Transplantation of 3D-ADSC rescued 50% of mice from FHF-induced lethality, whereas only 20% of mice survived when 2D-ADSC were transplanted. The improved transplantation outcomes correlated with the enhanced immunomodulatory effect of 3D-ADSC in the liver microenvironment.

Conclusion

The study shows that the transplantation of optimized 3D-ADSC can efficiently ameliorate GalN/LPS-induced FHF due to improved viability, resistance to exogenous ROS, and enhanced immunomodulatory effects of 3D-ADSC.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1337-3) contains supplementary material, which is available to authorized users.

Imaging Intestinal ROS in Homeostatic Conditions Using L-012

Reactive oxygen species (ROS) are critical redox regulators of cellular dynamics controlling homeostasis. Although numerous fluorescent probes are currently available to measure ROS in cell-based assays, the short-lived nature of these molecules renders their detection challenging in more complex biological systems, such as the gastrointestinal tract in vivo. However, in the past decade, significant progress has been made in the development of novel imaging technologies and probes, facilitating ROS quantification with high sensitivity, selectivity, and temporal resolution. The IVIS Spectrum (PerkinElmer) is an optical imaging system for small animal imaging allowing precise and noninvasive visualization of fluorescent or bioluminescent signals. Here, we describe a reproducible and comprehensive method for the measurement of physiological intestinal NADPH oxidase-derived ROS by using the chemiluminescent probe L-012. Using transgenic mice deficient in Nox isoforms expressed in the intestinal mucosa, we delineate the contribution of gut epithelial versus immune cell NADPH oxidase activity in homeostatic conditions. We also discuss L-012 probe specificity and potential alternatives for in vivo studies.

iNOS- and NOX1-dependent ROS production maintains bacterial homeostasis in the ileum of mice

The intestinal epithelial cells constitute the first line of defense against gut microbes, which includes secretion of various antimicrobial substances. Reactive oxygen species (ROS) are well characterized as part of the innate phagocytic immunity; however, a role in controlling microorganisms in the gut lumen is less clear. Here, we show a role for nitric oxide synthase (iNOS)- and NOX1-produced ROS in maintaining homeostasis of the gut microbiota. In vivo imaging revealed distinctly high levels of ROS in the ileum of normal healthy mice, regulated in accordance with the amount of gut bacteria. The ROS level was dependent on the nitric oxide and superoxide producers iNOS and NOX1, respectively, suggesting peroxynitrite as the effector molecule. In the ileum of iNOS- and NOX1-deficient mice, the bacterial load is increased and the composition is more cecum like. Our data suggest a unique role of ileum in maintaining homeostasis of gut microbes through production of ROS with potential importance for preventing reflux from the large intestine, bacterial overgrowth, and translocation.

IL-10 Paradoxically Promotes Autoimmune Neuropathy through S1PR1-Dependent CD4+ T Cell Migration

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a debilitating condition caused by autoimmune demyelination of peripheral nerves. CIDP is associated with increased IL-10, a cytokine with well-described anti-inflammatory effects. However, the role of IL-10 in CIDP is unclear. In this study, we demonstrate that IL-10 paradoxically exacerbates autoimmunity against peripheral nerves. In IL-10-deficient mice, protection from neuropathy was associated with an accrual of highly activated CD4+ T cells in draining lymph nodes and absence of infiltrating immune cells in peripheral nerves. Accumulated CD4+ T cells in draining lymph nodes of IL-10-deficient mice expressed lower sphingosine-1-phosphate receptor 1 (S1pr1), a protein important in lymphocyte egress. Additionally, IL-10 stimulation in vitro induced S1pr1 expression in lymph node cells in a STAT3-dependent manner. Together, these results delineate a novel mechanism in which IL-10-induced STAT3 increases S1pr1 expression and CD4+ T cell migration to accelerate T cell-mediated destruction of peripheral nerves.

Tailored Approaches in Drug Development and Diagnostics: From Molecular Design to Biological Model Systems

Approaches to increase the efficiency in developing drugs and diagnostics tools, including new drug delivery and diagnostic technologies, are needed for improved diagnosis and treatment of major diseases and health problems such as cancer, inflammatory diseases, chronic wounds, and antibiotic resistance. Development within several areas of research ranging from computational sciences, material sciences, bioengineering to biomedical sciences and bioimaging is needed to realize innovative drug development and diagnostic (DDD) approaches. Here, an overview of recent progresses within key areas that can provide customizable solutions to improve processes and the approaches taken within DDD is provided. Due to the broadness of the area, unfortunately all relevant aspects such as pharmacokinetics of bioactive molecules and delivery systems cannot be covered. Tailored approaches within (i) bioinformatics and computer-aided drug design, (ii) nanotechnology, (iii) novel materials and technologies for drug delivery and diagnostic systems, and (iv) disease models to predict safety and efficacy of medicines under development are focused on. Current developments and challenges ahead are discussed. The broad scope reflects the multidisciplinary nature of the field of DDD and aims to highlight the convergence of biological, pharmaceutical, and medical disciplines needed to meet the societal challenges of the 21st century.

Imaging of reactive oxygen species using [(3)H]hydromethidine in mice with cisplatin-induced nephrotoxicity

Background

Reactive oxygen species (ROS) have been implicated in cisplatin-induced nephrotoxicity. The aim of this study was to investigate the potential of using [³H]-labeled N-methyl-2,3-diamino-6-phenyl-dihydrophenanthridine ([³H]hydromethidine) for ex vivo imaging of regional ROS overproduction in mouse kidney induced by cisplatin.

Methods

Male C57BL/6 J mice were intraperitoneally administered with a single dose of cisplatin (30 mg/kg). Renal function was assessed by measuring serum creatinine and blood urea nitrogen (BUN) levels and morphology by histological examination. Renal malondialdehyde levels were measured as a lipid peroxidation marker. Autoradiographic studies were performed with kidney sections from mice at 60 min after [³H]hydromethidine injection.

Results

Radioactivity accumulation after [³H]hydromethidine injection was observed in the renal corticomedullary area of cisplatin-treated mice and was attenuated by pretreatment with dimethylthiourea (DMTU), a hydroxyl radical scavenger. Cisplatin administration significantly elevated serum creatinine and BUN levels, caused renal tissue damage, and promoted renal lipid peroxidation. These changes were significantly suppressed by DMTU pretreatment.

Conclusions

The present study showed that [³H]hydromethidine was rapidly distributed to the kidney after its injection and trapped there in the presence of ROS such as hydroxyl radicals, suggesting that [³H]hydromethidine is useful for assessment of the renal ROS amount in cisplatin-induced nephrotoxicity.

The amount of keratins matters for stress protection of the colonic epithelium

Keratins (K) are important for epithelial stress protection as evidenced by keratin mutations predisposing to human liver diseases and possibly inflammatory bowel diseases. A role for K8 in the colon is supported by the ulcerative colitis-phenotype with epithelial hyperproliferation and abnormal ion transport in K8-knockout (K8-/-) mice. The heterozygote knockout (K8+/-) colon appears normal but displays a partial ion transport-defect. Characterizing the colonic phenotype we show that K8+/- colon expresses ~50% less keratins compared to K8 wild type (K8+/+) but de novo K7 expression is observed in the top-most cells of the K8+/- and K8-/- crypts. The K8+/- colonic crypts are significantly longer due to increased epithelial hyperproliferation, but display no defects in apoptosis or inflammation in contrast to K8-/-. When exposed to colitis using the dextran sulphate sodium-model, K8+/- mice showed higher disease sensitivity and delayed recovery compared to K8+/+ littermates. Therefore, the K8+/- mild colonic phenotype correlates with decreased keratin levels and increased sensitivity to experimental colitis, suggesting that a sufficient amount of keratin is needed for efficient stress protection in the colonic epithelia.