Oxazolone and ethanol induce colitis in non-obese diabetic-severe combined immunodeficiency interleukin-2Rγ(null) mice engrafted with human peripheral blood mononuclear cells

Improvement effect of compound Ento-PB on oxazolone-induced ulcerative colitis in rats

PURPOSE

To investigate the impact of the Chinese medicine compound Ento-PB on oxazolone (OXZ)-induced ulcerative colitis (UC) in rats.

METHODS

UC rats induced by OXZ were treated with Ento-PB. The damage to the colon was assessed using several measures, including the disease activity index (DAI), colon length, colon weight/length ratio, colonic mucosal damage index, and histological score. The levels of interleukin-4 (IL-4), interleukin-10 (IL-10), interleukin-13 (IL-13), epidermal growth factor (EGF), inducible nitric oxide synthase, and total nitric oxide synthase (tNOS) in rat serum, as well as the levels of tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO) in rat colon tissue, were determined using enzyme-linked immunosorbent assay and conventional kits.

RESULTS

After being treated with Ento-PB, the DAI score and macroscopic lesion score of OXZ-induced UC rats were significantly reduced. Ento-PB prevented the shortening of rat colons, reduced the ratio of colon weight to length, and improved colon tissue lesions. Meanwhile, Ento-PB could significantly inhibit the activities of proinflammatory cytokines TNF-α, IL-13, and MPO, as well as tNOS and iNOS, while upregulating the expression of anti-inflammatory cytokines IL-4 and IL-10. Moreover, a significant increase in the expression level of EGF was observed in UC rats treated with Ento-PB, indicating that Ento-PB could enhance the repair of damaged intestinal epithelial tissue.

CONCLUSIONS

Ento-PB demonstrates significant anti-UC activities in OXZ-induced UC rats by regulating the expression levels of inflammatory factors and promoting the repair of colon tissue. This study provides scientific evidence to support the further development of Ento-PB.

Flagellin-specific human CAR Tregs for immune regulation in IBD

Regulatory T cell (Treg) therapy is a promising strategy to treat inflammatory bowel disease (IBD). Data from animal models has shown that Tregs specific for intestinal antigens are more potent than polyclonal Tregs at inhibiting colitis. Flagellins, the major structural proteins of bacterial flagella, are immunogenic antigens frequently targeted in IBD subjects, leading to the hypothesis that flagellin-specific Tregs could be an effective cell therapy for IBD. We developed a novel chimeric antigen receptor (CAR) specific for flagellin derived from Escherichia coli H18 (FliC). We used this CAR to confer FliC-specificity to human Tregs and investigated their therapeutic potential. FliC-CAR Tregs were activated by recombinant FliC protein but not a control flagellin protein, demonstrating CAR specificity and functionality. In a humanized mouse model, expression of the FliC-CAR drove preferential migration to the colon and expression of the activation marker PD1. In the presence of recombinant FliC protein in vitro, FliC-CAR Tregs were significantly more suppressive than control Tregs and promoted the establishment of colon-derived epithelial cell monolayers. These results demonstrate the potential of FliC-CAR Tregs to treat IBD and more broadly show the therapeutic potential of CARs targeting microbial-derived antigens.

Inflammatory Bowel Disease: A Review of Pre-Clinical Murine Models of Human Disease

Crohn’s disease (CD) and ulcerative colitis (UC) are both highly inflammatory diseases of the gastrointestinal tract, collectively known as inflammatory bowel disease (IBD). Although the cause of IBD is still unclear, several experimental IBD murine models have enabled researchers to make great inroads into understanding human IBD pathology. Here, we discuss the current pre-clinical experimental murine models for human IBD, including the chemical-induced trinitrobenzene sulfonic acid (TNBS) model, oxazolone and dextran sulphate sodium (DSS) models, the gene-deficient I-kappa-B kinase gamma (Iκκ-γ) and interleukin(IL)-10 models, and the CD4⁺ T-cell transfer model. We offer a comprehensive review of how these models have been used to dissect the etiopathogenesis of disease, alongside their limitations. Furthermore, the way in which this knowledge has led to the translation of experimental findings into novel clinical therapeutics is also discussed.

Development of a novel humanized mouse model for improved evaluation of in vivo anti-cancer effects of anti-PD-1 antibody

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer in the clinic. Further discovery of novel drugs or therapeutic protocols that enhance efficacy requires reliable animal models that recapitulate human immune responses to ICI treatment in vivo. In this study, we utilized an immunodeficient NOG mouse substrain deficient for mouse FcγR genes, NOG-FcγR^−/− mice, to evaluate the anti-cancer effects of nivolumab, an anti-programmed cell death-1 (PD-1) antibody. After reconstitution of human immune systems by human hematopoietic stem cell transplantation (huNOG-FcγR^−/− mice), four different programmed death-ligand 1 (PD-L1)-positive human cancer cell lines were tested. Among them, the growth of three cell lines was strongly suppressed by nivolumab in huNOG-FcγR^−/− mice, but not in conventional huNOG mice. Accordingly, immunohistochemistry demonstrated the enhanced infiltration of human T cells into tumor parenchyma in only nivolumab-treated huNOG-FcγR^−/− mice. Consistently, the number of human T cells was increased in the spleen in huNOG-FcγR^−/− mice by nivolumab but not in huNOG mice. Furthermore, human PD-L1 expression was strongly induced in the spleen of huNOG-FcγR^−/− mice. Collectively, our results suggest that the anti-cancer effects of anti-PD-1 antibodies can be detected more clearly in NOG-FcγR^−/− mice than in NOG mice.

Translating Treg Therapy for Inflammatory Bowel Disease in Humanized Mice

Crohn's disease and ulcerative colitis, two major forms of inflammatory bowel disease (IBD) in humans, afflicted in genetically predisposed individuals due to dysregulated immune response directed against constituents of gut flora. The defective immune responses mounted against the regulatory mechanisms amplify and maintain the IBD-induced mucosal inflammation. Therefore, restoring the balance between inflammatory and anti-inflammatory immunepathways in the gut may contribute to halting the IBD-associated tissue-damaging immune response. Phenotypic and functional characterization of various immune-suppressive T cells (regulatory T cells; Tregs) over the last decade has been used to optimize the procedures for in vitro expansion of these cells for developing therapeutic interventional strategies. In this paper, we review the mechanisms of action and functional importance of Tregs during the pathogenesis of IBD and modulating the disease induced inflammation as well as role of mouse models including humanized mice repopulated with the human immune system (HIS) to study the IBD. "Humanized" mouse models provide new tools to analyze human Treg ontogeny, immunobiology, and therapy and the role of Tregs in developing interventional strategies against IBD. Overall, humanized mouse models replicate the human conditions and prove a viable tool to study molecular functions of human Tregs to harness their therapeutic potential.

Murine models for studying immunopathogenesis in gastrointestinal lesions: How to go about it

Gastro-intestinal (GI) lesions are common outcome to diverse etiological agents affecting the GI tract. It requires significant expertise to accurately diagnose the fundamental cause and treat accordingly. A better understanding of the immunological underpinning of these lesions is of great importance to ensure their successful management. Availability of specific animal models allows us to understand the subtle differences among diverse disease conditions and help decide upon the treatment trajectories. Since murine models are best suited for studying the immunopathogenesis of any disease, we will restrict our discussions here to the available murine models and their applications to study gastrointestinal lesions. In this review, we have systematically examined and compared the variety of mice models that are routinely used to study Inflammatory Bowel disease (IBD) and also how they can be leveraged to address specific questions relating to IBD.

Functional characterization of oxazolone-induced colitis and survival improvement by vagus nerve stimulation

Background

Oxazolone-induced colitis has been frequently used in literature as a model of IBD, but insights into the underlying immune response and pathological features are surprisingly still very limited. Vagus nerve stimulation (VNS) has proven to be effective in innate and Th1/Th17 predominant inflammatory models, including pre-clinical models of colitis, however to what extent VNS is also effective in ameliorating Th2-driven colitis remains to be studied. In the present study, we therefore further characterized the immune response in oxazolone-induced colitis and investigated the potential therapeutic effect of VNS.

Methods

Colitis was induced in Balb/c mice by cutaneous sensitization with 3% oxazolone followed by intracolonic administration of 1% oxazolone 7 days later. To evaluate the effect of VNS on the development of Th2-driven colitis, VNS and sham-treated mice were challenged with 1% oxazolone.

Results

Intracolonic oxazolone administration resulted in a severe destruction of the colonic mucosa and a rapid drop in body temperature leading to a 65% mortality rate at day 5. Severe infiltration of neutrophils and monocytes was detected 6h after oxazolone administration which was associated with a Th2-type inflammatory response. VNS significantly improved survival rate which correlated with decreased levels of HMGB1 and reduced colonic (il6 and cxcl1 mRNA) and serum cytokine levels (IL-6, TNFα and CXCL1) compared to sham treated mice.

Conclusions

Oxazolone-induced colitis rather represents a model of sepsis and, at best, may resemble a severe type of ulcerative colitis, associated with early and severe mucosal damage and a high mortality rate. VNS reduces colonic inflammation and improves survival in this model, supporting the anti-inflammatory properties of VNS, even in an aggressive model as oxazolone-induced colitis.

Neural Network Modeling of AChE Inhibition by New Carbazole-Bearing Oxazolones

Acetylcholine esterase (AChE) is one of the targeted enzymes in the therapy of important neurodegenerative diseases such as Alzheimer's disease. Many studies on carbazole- and oxazolone-based compounds have been conducted in the last decade due to the importance of these compounds. New carbazole-bearing oxazolones were synthesized from several carbazole aldehydes and p-nitrobenzoyl glycine as AChE inhibitors by the Erlenmeyer reaction in the present study. The inhibitory effects of three carbazole-bearing oxazolone derivatives on AChE were studied in vitro and the experimental results were modeled using artificial neural network (ANN). The developed ANN provided sufficient correlation between several dependent systems, including enzyme inhibition. The inhibition data for AChE were modeled by a two-layered ANN architecture. High correlation coefficients were observed between the experimental and predicted ANN results. Synthesized carbazole-bearing oxazolone derivatives inhibited AChE under in vitro conditions, and further research involving in vivo studies is recommended. An ANN may be a useful alternative modeling approach for enzyme inhibition.

Humanized mice: A brief overview on their diverse applications in biomedical research

Model animals naturally differ from humans in various respects and results from the former are not directly translatable to the latter. One approach to address this issue is humanized mice that are defined as mice engrafted with functional human cells or tissues. In humanized mice, we can investigate the development and function of human cells or tissues (including their products encoded by human genes) in the in vivo context of a small animal. As such, humanized mouse models have played important roles that cannot be substituted by other animal models in various areas of biomedical research. Although there are obvious limitations in humanized mice and we may need some caution in interpreting the results obtained from them, it is reasonably expected that they will be utilized in increasingly diverse areas of biomedical research, as the technology for preparing humanized mice are rapidly improved. In this review, I will describe the methodology for generating humanized mice and overview their recent applications in various disciplines including immunology, infectious diseases, drug metabolism, and neuroscience.

Humanized Mouse Models of Clinical Disease

Immunodeficient mice engrafted with functional human cells and tissues, that is, humanized mice, have become increasingly important as small, preclinical animal models for the study of human diseases. Since the description of immunodeficient mice bearing mutations in the IL2 receptor common gamma chain (IL2rg^null) in the early 2000s, investigators have been able to engraft murine recipients with human hematopoietic stem cells that develop into functional human immune systems. These mice can also be engrafted with human tissues such as islets, liver, skin, and most solid and hematologic cancers. Humanized mice are permitting significant progress in studies of human infectious disease, cancer, regenerative medicine, graft-versus-host disease, allergies, and immunity. Ultimately, use of humanized mice may lead to the implementation of truly personalized medicine in the clinic. This review discusses recent progress in the development and use of humanized mice and highlights their utility for the study of human diseases.

A mouse model for ulcerative colitis based on NOD-scid IL2R γnull mice reconstituted with peripheral blood mononuclear cells from affected individuals

Animal models reflective of ulcerative colitis (UC) remain a major challenge, and yet are crucial to understand mechanisms underlying the onset of disease and inflammatory characteristics of relapses and remission. Mouse models in which colitis-like symptoms are induced through challenge with toxins such as oxazolone, dextran sodium sulfate (DSS) or 2,4,6-trinitrobenzenesulfonic acid (TNBS) have been instrumental in understanding the inflammatory processes of UC. However, these neither reflect the heterogeneous symptoms observed in the UC-affected population nor can they be used to test the efficacy of inhibitors developed against human targets where high sequence and structural similarity of the respective ligands is lacking. In an attempt to overcome these problems, we have developed a mouse model that relies on NOD-scid IL2R γ^null mice reconstituted with peripheral blood mononuclear cells derived from UC-affected individuals. Upon challenge with ethanol, mice developed colitis-like symptoms and changes in the colon architecture, characterized by influx of inflammatory cells, edema, crypt loss, crypt abscesses and epithelial hyperplasia, as previously observed in immune-competent mice. TARC, TGFβ1 and HGF expression increased in distal parts of the colon. Analysis of human leucocytes isolated from mouse spleen revealed an increase in frequencies of CD1a+, CD64+, CD163+ and TSLPR+ CD14+ monocytes, and antigen-experienced CD44+ CD4+ and CD8+ T-cells in response to ethanol. Analysis of human leucocytes from the colon of challenged mice identified CD14+ monocytes and CD11b+ monocytes as the predominant populations. Quantitative real-time PCR (RT-PCR) analysis from distal parts of the colon indicated that IFNγ might be one of the cytokines driving inflammation. Treatment with infliximab ameliorated symptoms and pathological manifestations, whereas pitrakinra had no therapeutic benefit. Thus, this model is partially reflective of the human disease and might help to increase the translation of animal and clinical studies.

Summary: The phenotype and colitis-like symptoms induced in NSG mice reconstituted with PBMCs derived from ulcerative-colitis-affected donors reflect the human disease.

Oxazolone-Induced Colitis as a Model of Th2 Immune Responses in the Intestinal Mucosa

Murine models of intestinal inflammation have been widely used in biomedical research. Similarities in anatomy and physiology between such murine models and patients with inflammatory bowel diseases may allow a better understanding of the pathogenesis of Crohn's disease and ulcerative colitis. Additionally, models of intestinal inflammation may be used for the analysis of potentially new therapeutic agents. One key class of models consists of chemically induced inflammation models. Within this group, colitis induced by the haptenizing agent oxazolone is an important model that results in induction of acute or chronic inflammation of the large bowel. Here, we describe the induction and the analysis of this experimental colitis model.

Use of Humanized Mice to Study the Pathogenesis of Autoimmune and Inflammatory Diseases

Animal models of disease have been used extensively by the research community for the past several decades to better understand the pathogenesis of different diseases and assess the efficacy and toxicity of different therapeutic agents. Retrospective analyses of numerous preclinical intervention studies using mouse models of acute and chronic inflammatory diseases reveal a generalized failure to translate promising interventions or therapeutics into clinically effective treatments in patients. Although several possible reasons have been suggested to account for this generalized failure to translate therapeutic efficacy from the laboratory bench to the patient's bedside, it is becoming increasingly apparent that the mouse immune system is substantially different from the human. Indeed, it is well known that >80 major differences exist between mouse and human immunology; all of which contribute to significant differences in immune system development, activation, and responses to challenges in innate and adaptive immunity. This inconvenient reality has prompted investigators to attempt to humanize the mouse immune system to address important human-specific questions that are impossible to study in patients. The successful long-term engraftment of human hematolymphoid cells in mice would provide investigators with a relatively inexpensive small animal model to study clinically relevant mechanisms and facilitate the evaluation of human-specific therapies in vivo. The discovery that targeted mutation of the IL-2 receptor common gamma chain in lymphopenic mice allows for the long-term engraftment of functional human immune cells has advanced greatly our ability to humanize the mouse immune system. The objective of this review is to present a brief overview of the recent advances that have been made in the development and use of humanized mice with special emphasis on autoimmune and chronic inflammatory diseases. In addition, we discuss the use of these unique mouse models to define the human-specific immunopathological mechanisms responsible for the induction and perpetuation of chronic gut inflammation.

The route to pathologies in chronic inflammatory diseases characterized by T helper type 2 immune cells

T helper type 2 (Th2)-characterized inflammatory responses are highly dynamic processes initiated by epithelial cell damage resulting in remodelling of the tissue architecture to prevent further harm caused by a dysfunctional epithelial barrier or migrating parasites. This process is a temporal and spatial response which requires communication between immobile cells such as epithelial, endothelial, fibroblast and muscle cells and the highly mobile cells of the innate and adaptive immunity. It is further characterized by a high cellular plasticity that enables the cells to adapt to a specific inflammatory milieu. Incipiently, this milieu is shaped by cytokines released from epithelial cells, which stimulate Th2, innate lymphoid and invariant natural killer (NK) T cells to secrete Th2 cytokines and to activate dendritic cells which results in the further differentiation of Th2 cells. This milieu promotes wound-healing processes which are beneficial in parasitic infections or toxin exposure but account for increasingly dysfunctional vital organs, such as the lung in the case of asthma and the colon in ulcerative colitis. A better understanding of the dynamics underlying relapses and remissions might lead ultimately to improved therapeutics for chronic inflammatory diseases adapted to individual needs and to different phases of the inflammation.

Functional engraftment of human peripheral T and B cells and sustained production of autoantibodies in NOD/LtSzscid/IL-2Rγ(-/-) mice

NOD/LtSzscid/IL-2Rγ(-/-) (NSG) mice have advantages in establishing humanized mouse models. However, transferring human PBMCs into these mice often causes lethal GVH disease. In this study, we discovered an improved method for the engraftment of normal or pathological human PBMCs into NSG mice and examined the subsequent induction of specific immune responses. We sequentially transferred human CD4+ memory T (Tm) and B cells obtained from PBMCs of healthy adults or patients with autoimmune diseases into NSG mice. Removing naïve CD4+ T cells from the transferred PBMCs allowed successful engraftment without lethal GVH disease. The transferred Tm cells were found to reside mainly in the spleen and the lymphoid nodules, where they expressed MHC class II molecules and produced cytokines, including IL-21. Surprisingly, the transferred B cells were also well maintained in the lymphoid organs, underwent de novo class-switch recombination, and secreted all isotypes of human Igs at significant levels. Moreover, transferring patient-derived Tm and B cells resulted in sustained production of IgM-rheumatoid factor and antiaminoacyl transfer RNA synthetase Abs in these mice. These results suggest that transfer of Tm and B cells derived from human PBMCs into NSG mice could be a useful method for the study of human autoimmune mechanisms.

NOD-scid IL2R γnull mice engrafted with human peripheral blood mononuclear cells as a model to test therapeutics targeting human signaling pathways

BACKGROUND

Animal models of human inflammatory diseases have limited predictive quality for human clinical trials for various reasons including species specific activation mechanisms and the immunological background of the animals which markedly differs from the genetically heterogeneous and often aged patient population.

OBJECTIVE

Development of an animal model allowing for testing therapeutics targeting pathways involved in the development of Atopic Dermatitis (AD) with better translatability to the patient.

METHODS

NOD-scid IL2R γnull mice engrafted with human peripheral blood mononuclear cells (hPBMC) derived from patients suffering from AD and healthy volunteers were treated with IL-4 and the antagonistic IL-4 variant R121/Y124D (Pitrakinra). Levels of human (h)IgE, amount of B-, T- and plasma- cells and ratio of CD4 : CD8 positive cells served as read out for induction and inhibition of cell proliferation and hIgE secretion. Results were compared to in vitro analysis.

RESULTS

hIgE secretion was induced by IL-4 and inhibited by the IL-4 antagonist Pitrakinra in vivo when formulated with methylcellulose. B-cells proliferated in response to IL-4 in vivo; the effect was abrogated by Pitrakinra. IL-4 shifted CD4 : CD8 ratios in vitro and in vivo when hPBMC derived from healthy volunteers were used. Pitrakinra reversed the effect. Human PBMC derived from patients with AD remained inert and engrafted mice reflected the individual responses observed in vitro.

CONCLUSION

NOD-scid IL2R γnull mice engrafted with human PBMC reflect the immunological history of the donors and provide a complementary tool to in vitro studies. Thus, studies in this model might provide data with better translatability from bench to bedside.