Peyer's patches and mesenteric lymph nodes cooperatively promote enteropathy in a mouse model of food allergy

Quercetin Improves Barrier Properties in Porcine Small Intestine but Not in Peyer's Patches

Peyer's patches (PPs) are part of the gut-associated lymphatic tissue (GALT) and represent the first line of the intestinal immunological defense. They consist of follicles with lymphocytes and an overlying subepithelial dome with dendritic cells and macrophages, and they are covered by the follicle-associated epithelium (FAE). A sealed paracellular pathway in the FAE is crucial for the controlled uptake of luminal antigens. Quercetin is the most abundant plant flavonoid and has a barrier-strengthening effect on tight junctions (TJs), a protein complex that regulates the paracellular pathway. In this study, we aimed to analyze the effect of quercetin on porcine PPs and the surrounding villus epithelium (VE). We incubated both tissue types for 4 h in Ussing chambers, recorded the transepithelial electrical resistance (TEER), and measured the unidirectional tracer flux of [3H]-mannitol. Subsequently, we analyzed the expression, protein amount, and localization of three TJ proteins, claudin 1, claudin 2, and claudin 4. In the PPs, we could not detect an effect of quercetin after 4 h, neither on TEER nor on the [3H]-mannitol flux. In the VE, quercetin led to a higher TEER value, while the [3H]-mannitol flux was unchanged. The pore-forming claudin 2 was decreased while the barrier-forming claudin 4 was increased and the expression was upregulated. Claudin 1 was unchanged and all claudins could be located in the paracellular membrane by immunofluorescence microscopy. Our study shows the barrier-strengthening effect of quercetin in porcine VE by claudin 4 upregulation and a claudin 2 decrease. Moreover, it underlines the different barrier properties of PPs compared to the VE.

Open multi-organ communication device for easy interrogation of tissue slices

Here, we have developed an open multi-organ communication device that facilitates cellular and molecular communication between ex vivo organ slices. Measuring communication between organs is vital for understanding the mechanisms of health regulation yet remains difficult with current technology. Communication between organs along the gut-brain-immune axis is a key regulator of gut homeostasis. As a novel application of the device, we have used tissue slices from the Peyer's patch (PP) and mesenteric lymph node (MLN) due to their importance in gut immunity; however, any organ slices could be used here. The device was designed and fabricated using a combination of 3D printed molds for polydimethylsiloxane (PDMS) soft lithography, PDMS membranes, and track-etch porous membranes. To validate cellular and protein transfer between organs on-chip, we used fluorescence microscopy to quantitate movement of fluorescent proteins and cells from the PP to the MLN, replicating the initial response to immune stimuli in the gut. IFN-γ secretion during perfusion from a naïve vs. inflamed PP to a healthy MLN was quantitated to demonstrate soluble signaling molecules are moving on-chip. Finally, transient catecholamine release was measured during perfusion from PP to MLN using fast-scan cyclic voltammetry at carbon-fiber microelectrodes to demonstrate a novel application of the device for real-time sensing during communication. Overall, we show an open-well multi-organ device capable of facilitating transfer of soluble factors and cells with the added benefit of being available for external analysis techniques like electrochemical sensing which will advance abilities to probe communication in real-time across multiple organs ex vivo.

Experimental allergic airway inflammation impacts gut homeostasis in mice

Background

/Aims: Epidemiological data show that there is an important relationship between respiratory and intestinal diseases. To improve our understanding on the interconnectedness between the lung and intestinal mucosa and the overlap between respiratory and intestinal diseases, our aim was to investigate the influence of ovalbumin (OVA)-induced allergic airway inflammation on gut homeostasis.

Methods

A/J mice were sensitized and challenged with OVA. The animals were euthanized 24 h after the last challenge, lung inflammation was determined by evaluating cells in Bronchoalveolar lavage fluid, serum anti-OVA IgG titers and colon morphology, inflammation and integrity of the intestinal mucosa were investigated. IL-4 and IL-13 levels and myeloperoxidase activity were determined in the colon samples. The expression of genes involved in inflammation and mucin production at the gut mucosa was also evaluated.

Results

OVA challenge resulted not only in lung inflammation but also in macroscopic alterations in the gut such as colon shortening, increased myeloperoxidase activity and loss of integrity in the colonic mucosal. Neutral mucin intensity was lower in the OVA group, which was followed by down-regulation of transcription of ATOH1 and up-regulation of TJP1 and MUC2. In addition, the OVA group had higher levels of IL-13 and IL-4 in the colon. Ova-specific IgG1 and OVA-specific IgG2a titers were higher in the serum of the OVA group than in controls.

Conclusions

Our data using the OVA experimental model suggested that challenges in the respiratory system may result not only in allergic airway inflammation but also in the loss of gut homeostasis.

Effects of Lactobacillus on the Differentiation of Intestinal Mucosa Immune Cells and the Composition of Gut Microbiota in Soybean-Sensitized Mice

In the early stage of this study, three strains of Lactobacillus with anti-soybean allergy potential were screened: Lactobacillus acidophilus CICC 6081, Lactobacillus delbrueckii subsp. Bulgaricus CICC 6103 and Lactobacillus plantarum subsp. Plantarum CICC 20988. The aim of this study was to analyze the desensitization effect of three strains of Lactobacillus administered by gavage to soybean-allergic mice through the differentiation of immune cells in intestinal lymph nodes and the changes to gut microbiota. The results showed that the three strains of Lactobacillus could stimulate the proliferation of dendritic cells (DCs) and regulate the balance of Th1/Th2 differentiation in the MLNs and PPs of soybean-allergic mice. Furthermore, the Th17/Tregs cell-differentiation ratio in the MLNs of the Lactobacillus-treated mice was significantly lower than that of the allergic mice (p < 0.05). Compared to the control group, the Shannon, Sobs and Ace indexes of intestinal microbiota in the allergic mice were significantly increased (p < 0.05), and the proportion of Clostridiales was significantly higher (p < 0.05), which was reversed by Lactobacillus gavage. In conclusion, the three strains of Lactobacillus can inhibit the intestinal mucosal immune response and regulate gut microbiota balance in soybean-allergic mice.

Barrier Perturbation in Porcine Peyer’s Patches by Tumor Necrosis Factor is Associated With a Dysregulation of Claudins

The proinflammatory cytokine tumor necrosis factor (TNF) has been described as one of the main mediators of intestinal inflammatory diseases, affecting the composition of tight junction (TJ) proteins and leading to a disruption of the epithelial barrier. An intact intestinal barrier is mandatory, because the follicle-associated epithelium of Peyer’s patches represents the first defense line of the intestinal immune system and ensures a controlled uptake of antigens from the gut lumen. In the current study, we have analyzed the detailed effects of TNF on the follicle-associated epithelium of porcine Peyer’s patches by applying the Ussing chamber technique. Epithelial tissue specimens of Peyer’s patches and the surrounding villus epithelium were mounted into conventional Ussing chambers and incubated with TNF for 10 h. The transepithelial resistance, representing epithelial barrier function of the tissue, was recorded. A reduction of transepithelial resistance was detected after 8 h in Peyer’s patch tissue specimens, whereas the villus epithelium was not significantly affected by TNF. Subsequent molecular analysis of TJ protein expression revealed a marked decrease of claudin-1 and -4, and an increase of claudin-2. In neighboring villus epithelium, no significant changes in the expression of TJ proteins could be shown. A strong increase of TNF receptor-2 (TNFR-2) could also be detected in Peyer’s patches, in agreement with the major role of this receptor in Peyer’s patches. Our findings were in accordance with changes detected by confocal laser scanning immunofluorescence microscopy. The regulation of TNF effects via myosin light chain kinase (MLCK) was analyzed in blocking experiments. Our detailed analysis is the first to show that TNF affects the barrier function of the follicle-associated epithelium of porcine Peyer’s patches but has no effects on the villus epithelium. These findings reveal not only the basic differences of epithelial barrier function between the two structures, but also the significance of Peyer’s patches as a primary mucosal immune defense.

Extracts of <i>Gluconacetobacter hansenii</i> GK-1 induce Foxp3⁺T cells in food-allergic mice by an IL-4-dependent or IL-4-independent mechanism

The biological activities of acetic acid bacteria (AAB) as Gram-negative bacteria have attracted our interests, especially in their inhibitory effects on allergic responses. To clarify the underlying mechanism that improves allergic symptoms by ingestion of the AAB Gluconacetobacter hansenii, we examined whether different extracts of heat-killed G. hansenii GK-1 could reduce the interleukin (IL)-4 production of immune cells from food-allergic model of OVA23-3, transgenic mice with ovalbumin (OVA)-specific T-cell-receptor genes. A hot-water extract fraction (FII) of G. hansenii GK-1 significantly decreased the in vitro IL-4 production of spleen cells of OVA23-3 mice compared with those stimulated with OVA alone. The IL-4 inhibitory effect was also observed for FIV (purified lipopolysaccharide (LPS) fraction), but the activity was lower than for FII or LPS from Escherichia coli. Unlike LPS from Escherichia coli, FIV significantly inhibited the LPS-induced IL-6 production of the spleen cells. The addition of FII or FIV to a Foxp3⁺T cell-inducing culture showed that FII significantly promoted the rate of Foxp3⁺CD4⁺T cells of OVA-stimulated mesenteric lymph node cells from recombination-activating-gene (RAG)-2-deficient food-allergic inflammatory OVA23-3 (R23-3) mice with suppression of IL-4 production, while FIV induced Foxp3⁺T cells from RAG-2-deficient DO11.10 non-inflammatory mice. Structure analysis showed a lack of O-antigen in FIV, which seemed to lead to the weak biological activities of FIV observed. The present study suggests that extracts of G. hansenii GK-1 to inhibit IL-4 production of immune cells and/or promote regulatory T cell differentiation synergistically play important roles in improving allergic symptoms safely as well as normal condition.

Non-IgE-Mediated Gastrointestinal Food Protein-Induced Allergic Disorders. Clinical Perspectives and Analytical Approaches

Non-IgE-mediated gastrointestinal food allergy (non-IgE-GI-FA) is the name given to a series of pathologies whose main entities are food protein-induced allergic proctocolitis (FPIAP), food protein-induced enteropathy (FPE), and food protein-induced enterocolitis syndrome (FPIES). These are more uncommon than IgE-mediated food allergies, their mechanisms remain largely unknown, and their diagnosis is mainly done by clinical history, due to the lack of specific biomarkers. In this review, we present the latest advances found in the literature about clinical aspects, the current diagnosis, and treatment options of non-IgE-GI-FAs. We discuss the use of animal models, the analysis of gut microbiota, omics techniques, and fecal proteins with a focus on understanding the pathophysiological mechanisms of these pathologies and obtaining possible diagnostic and/or prognostic biomarkers. Finally, we discuss the unmet needs that researchers should tackle to advance in the knowledge of these barely explored pathologies.

Effector memory CD4+T cells in mesenteric lymph nodes mediate bone loss in food-allergic enteropathy model mice, creating IL-4 dominance

Intestinal inflammation can be accompanied by osteoporosis, but their relationship, mediated by immune responses, remains unclear. Here, we investigated a non-IgE-mediated food-allergic enteropathy model of ovalbumin (OVA) 23-3 mice expressing OVA-specific T-cell-receptor transgenes. Mesenteric lymph nodes (MLNs) and their pathogenic CD4⁺T cells were important to enteropathy occurrence and exacerbation when the mice were fed an egg-white (EW) diet. EW-fed OVA23-3 mice also developed bone loss and increased CD44^hiCD62L^loCD4⁺T cells in the MLNs and bone marrow (BM); these changes were attenuated by MLN, but not spleen, resection. We fed an EW diet to F1 cross offspring from OVA23-3 mice and a mouse line expressing the photoconvertible protein KikGR to track MLN CD4⁺T cells. Photoconverted MLN CD44^hiCD62L^loCD4⁺T cells migrated predominantly to the BM; pit formation assay proved their ability to promote bone damage via osteoclasts. Significantly greater expression of IL-4 mRNA in MLN CD44^hiCD62L^loCD4⁺T cells and bone was observed in EW-fed OVA23-3 mice. Anti-IL-4 monoclonal antibody injection canceled bone loss in the primary inflammation phase in EW-fed mice, but less so in the chronic phase. This novel report shows the specific inflammatory relationship, via Th2-dominant-OVA-specific T cells and IL-4 production, between MLNs and bone, a distant organ, in food-allergic enteropathy.

Selenium Modulates the Allergic Response to Whey Protein in a Mouse Model for Cow's Milk Allergy

Cow's milk allergy is a common food allergy in infants, and is associated with an increased risk of developing other allergic diseases. Dietary selenium (Se), one of the essential micronutrients for humans and animals, is an important bioelement which can influence both innate and adaptive immune responses. However, the effects of Se on food allergy are still largely unknown. In the current study it was investigated whether dietary Se supplementation can inhibit whey-induced food allergy in an animal research model. Three-week-old female C3H/HeOuJ mice were intragastrically sensitized with whey protein and cholera toxin and randomly assigned to receive a control, low, medium or high Se diet. Acute allergic symptoms, allergen specific immunoglobulin (Ig) E levels and mast cell degranulation were determined upon whey challenge. Body temperature was significantly higher in mice that received the medium Se diet 60 min after the oral challenge with whey compared to the positive control group, which is indicative of impaired anaphylaxis. This was accompanied by reductions in antigen-specific immunoglobulins and reduced levels of mouse mast cell protease-1 (mMCP-1). This study demonstrates that oral Se supplementation may modulate allergic responses to whey by decreasing specific antibody responses and mMCP-1 release.

Role of CD4+ T Cells in Allergic Airway Diseases: Learning from Murine Models

The essential contribution of CD4⁺ T cells in allergic airway diseases has been demonstrated, especially by using various murine models of antigen-induced airway inflammation. In addition to antigen-immunized mouse models employing mast cell-deficient mice and CD4⁺ T cell-depleting procedure, antigen-specific CD4⁺ T cell transfer models have revealed the possible development of allergic inflammation solely dependent on CD4⁺ T cells. Regardless of the classical Th1/Th2 theory, various helper T cell subsets have the potential to induce different types of allergic inflammation. T cell receptor (TCR)-transgenic (Tg) mice have been used for investigating T cell-mediated immune responses. Besides, we have recently generated cloned mice from antigen-specific CD4⁺ T cells through somatic cell nuclear transfer. In contrast to TCR-Tg mice that express artificially introduced TCR, the cloned mice express endogenously regulated antigen-specific TCR. Upon antigen exposure, the mite antigen-reactive T cell-cloned mice displayed strong airway inflammation accompanied by bronchial hyperresponsiveness in a short time period. Antigen-specific CD4⁺ T cell-cloned mice are expected to be useful for investigating the detailed role of CD4⁺ T cells in various allergic diseases and for evaluating novel anti-allergic drugs.

Protective Effect of Glycomacropeptide on Food Allergy with Gastrointestinal Manifestations in a Rat Model through Down-Regulation of Type 2 Immune Response

Glycomacropeptide (GMP) is a bioactive peptide derived from milk κ-casein with immune-modulatory and anti-inflammatory properties. Food allergy (FA) is an adverse immune reaction with a broad spectrum of manifestations. Allergen intake induces persistent intestinal inflammation and tissue damage. In this study, the anti-allergic activity of GMP was evaluated using a rat ovalbumin (OVA)-induced FA model with gastrointestinal manifestation. Rats were orally GMP treated from 3 days prior and during FA development. The severity of food anaphylaxis and diarrheal episodes, antibody production and histamine level were measured. Histopathological changes, inflammation and predominant cytokine profile at intestine were analyzed. Oral GMP intake decreased clinical signs and diarrhea severity induced by allergen, with a significant reduction in intestinal edema and expression level of IL-1β and TNF-α. Prophylaxis with GMP also diminished serum anti-OVA IgE and IgG1, and histamine levels. GMP treatment markedly decreased eosinophil infiltration, mast cell and goblet cell hyperplasia, total IgE expression in intestine, and prevented histological changes in villi, crypts and internal muscularis layer. The treatment effectively suppressed IL-5, IL-13 and GATA3 expression and skewed the intestinal cytokine profile toward type 1 and regulatory. These results suggest that GMP may protect against FA through down-regulating the type 2 inflammatory response.

Evaluation of Immunoreactivity of Pea (Pisum sativum) Albumins in BALB/c and C57BL/6 Mice

Green pea (Pisum sativum) is a component of European cuisine; however, an estimated 0.8% of Europeans suffer from allergies to pea proteins. We examined the immunoreactive potential of pea albumins (PA) in BALB/c and C57BL/6 mice. Mice were orally gavaged with PA or glycated pea albumins (G-PA) for 10 consecutive days, in combination with an adjuvant. Both PA and G-PA increased PA-specific serum antibody titers to about 212 for anti-PA IgG, ∼27 for anti-PA IgA, and ∼27.8 for anti-PA IgA in fecal extracts (p < 0.001). On day 42 postexposure, the antibodies titers decreased and were greater in BALB/c compared to C57BL/6 mice (p < 0.05). Distribution of CD4+ and CD8+ T cells in lymphoid tissues presented strain-specific differences. PA was found to induce lymphocyte proliferation; however, G-PA did not. Both PA and G-PA changed CD4+ and CD8+ T cells percentages in some lymphoid tissues; however, this did not impact cytokines production by splenocyte cultures evidenced by the stimulation of Th1, Th2, and Th17 cells. The observed immunomodulatory properties of PA and G-PA and lack of a sign of allergic reaction render them suitable for supplements in personalized diets, but further research is needed to precisely understand this activity.

Overview of in vivo and ex vivo endpoints in murine food allergy models: Suitable for evaluation of the sensitizing capacity of novel proteins?

Significant efforts are necessary to introduce new dietary protein sources to feed a growing world population while maintaining food supply chain sustainability. Such a sustainable protein transition includes the use of highly modified proteins from side streams or the introduction of new protein sources that may lead to increased clinically relevant allergic sensitization. With food allergy being a major health problem of increasing concern, understanding the potential allergenicity of new or modified proteins is crucial to ensure public health protection. The best predictive risk assessment methods currently relied on are in vivo models, making the choice of endpoint parameters a key element in evaluating the sensitizing capacity of novel proteins. Here, we provide a comprehensive overview of the most frequently used in vivo and ex vivo endpoints in murine food allergy models, addressing their strengths and limitations for assessing sensitization risks. For optimal laboratory‐to‐laboratory reproducibility and reliable use of predictive tests for protein risk assessment, it is important that researchers maintain and apply the same relevant parameters and procedures. Thus, there is an urgent need for a consensus on key food allergy parameters to be applied in future food allergy research in synergy between both knowledge institutes and clinicians.

Suppressive effect of dietary resistant maltodextrin on systemic immunity in a mouse model of food allergy

Resistant maltodextrin (RMD) is a soluble dietary fibre that exerts several physiological functions as a result of its microbial degradation and changes in the intestinal environment. It has been reported that RMD enhanced immunoglobulin A (IgA) secretion, which protects the mucosa from foreign substances. However, the effect of RMD on excessive immunity has yet to be investigated. In this study, we aimed to investigate the effect of RMD on excessive immune responses such as food allergy. OVA23-3 mice were fed an AIN-76-based diet containing 20% egg-white protein with or without RMD. While RMD was shown to contribute to an increase in goblet cells, RMD did not change the overall inflammatory status when ingested with the egg-white diet. RMD suppressed IL-4 and IL-10 production from splenocytes but not cells from mesenteric lymph nodes. RMD also downregulated the serum levels of OVA-specific Th1- and Th2-related antibodies, which were elevated in the food-allergic condition. RMD significantly increased the total amount of short-chain fatty acids, especially acetate and propionate, in the caecum of OVA23-3 mice fed the egg-white diet. Our study demonstrated that dietary RMD modulates systemic rather than intestinal antigen-specific immune responses in the food-allergic condition of OVA23-3 mice. Although the relevant mechanism has yet to be investigated, RMD shows potential for alleviating food allergy through adjustment of systemic immunity.

Critical role of intestinal interleukin-4 modulating regulatory T cells for desensitization, tolerance, and inflammation of food allergy

Background and objective

The mechanism inducing either inflammation or tolerance to orally administered food allergens remains unclear. To investigate this we analyzed mouse models of food allergy (OVA23-3) and tolerance (DO11.10 [D10]), both of which express ovalbumin (OVA)-specific T-cell receptors.

Methods

OVA23-3, recombination activating gene (RAG)-2-deficient OVA23-3 (R23-3), D10, and RAG-2-deficient D10 (RD10) mice consumed a diet containing egg white (EW diet) for 2–28 days. Interleukin (IL)-4 production by CD4⁺ T cells was measured as a causative factor of enteropathy, and anti-IL-4 antibody was used to reveal the role of Foxp3⁺ OVA-specific Tregs (aiTreg) in this process.

Results

Unlike OVA23-3 and R23-3 mice, D10 and RD10 mice did not develop enteropathy and weight loss on the EW diet. On days 7–10, in EW-fed D10 and RD10 mice, splenic CD4⁺ T cells produced significantly more IL-4 than did those in the mesenteric lymph nodes (MLNs); this is in contrast to the excessive IL-4 response in the MLNs of EW-fed OVA23-3 and R23-3 mice. EW-fed R23-3 mice had few aiTregs, whereas EW-fed RD10 mice had them in both tissues. Intravenous injections of anti-IL-4 antibody recovered the percentage of aiTregs in the MLNs of R23-3 mice. On day 28, in EW-fed OVA23-3 and R23-3 mice, expression of Foxp3 on CD4⁺ T cells corresponded with recovery from inflammation, but recurrence of weight loss was observed on restarting the EW diet after receiving the control-diet for 1 month. No recurrence developed in D10 mice.

Conclusions

Excessive IL-4 levels in the MLNs directly inhibited the induction of aiTregs and caused enteropathy. The aiTregs generated in the attenuation of T cell-dependent food allergic enteropathy may function differently than aiTregs induced in a tolerance model. Comparing the two models enables to investigate their aiTreg functions and to clarify differences between inflammation with subsequent desensitization versus tolerance.

Estradiol Synthesis in Gut-Associated Lymphoid Tissue: Leukocyte Regulation by a Sexually Monomorphic System

17β-estradiol is a potent sex hormone synthesized primarily by gonads in females and males that regulates development and function of the reproductive system. Recent studies show that 17β-estradiol is locally synthesized in nonreproductive tissues and regulates a myriad of events, including local inflammatory responses. In this study, we report that mesenteric lymph nodes (mLNs) and Peyer's patches (Pps) are novel sites of de novo synthesis of 17β-estradiol. These secondary lymphoid organs are located within or close to the gastrointestinal tract, contain leukocytes, and function at the forefront of immune surveillance. 17β-estradiol synthesis was initially identified using a transgenic mouse with red fluorescent protein coexpressed in cells that express aromatase, the enzyme responsible for 17β-estradiol synthesis. Subsequent immunohistochemistry and tissue culture experiments revealed that aromatase expression was localized to high endothelial venules of these lymphoid organs, and these high endothelial venule cells synthesized 17β-estradiol when isolated and cultured in vitro. Both mLNs and Pps contained 17β-estradiol with concentrations that were significantly higher than those of peripheral blood. Furthermore, the total amount of 17β-estradiol in these organs exceeded that of the gonads. Mice lacking either aromatase or estrogen receptor-β had hypertrophic Pps and mLNs with more leukocytes than their wild-type littermates, demonstrating a role for 17β-estradiol in leukocyte regulation. Importantly, we did not observe any sex-dependent differences in aromatase expression, 17β-estradiol content, or steroidogenic capacity in these lymphoid organs.

Current challenges facing the assessment of the allergenic capacity of food allergens in animal models

Food allergy is a major health problem of increasing concern. The insufficiency of protein sources for human nutrition in a world with a growing population is also a significant problem. The introduction of new protein sources into the diet, such as newly developed innovative foods or foods produced using new technologies and production processes, insects, algae, duckweed, or agricultural products from third countries, creates the opportunity for development of new food allergies, and this in turn has driven the need to develop test methods capable of characterizing the allergenic potential of novel food proteins. There is no doubt that robust and reliable animal models for the identification and characterization of food allergens would be valuable tools for safety assessment. However, although various animal models have been proposed for this purpose, to date, none have been formally validated as predictive and none are currently suitable to test the allergenic potential of new foods. Here, the design of various animal models are reviewed, including among others considerations of species and strain, diet, route of administration, dose and formulation of the test protein, relevant controls and endpoints measured.

Targeting Immunomodulatory Agents to the Gut-Associated Lymphoid Tissue

In addition to fluid haemostasis and lipid absorption, the lymphatic system and lymphoid tissues serve as the major host of immune cells where immune responses are evoked. Impaired function of the immune system might lead to serious diseases which are often treated by immunomodulators. This chapter briefly explores the physiology of an important part of the lymphatic system, the gut-associated lymphoid tissues (GALT). Currently used strategies for targeting GALT by immunomodulators for enhanced activity and/or decreased side effects are discussed. Strategies range from simple oral co-administration of immunomodulators with lipids to more advanced lipid-based formulations, polymer-based nanoparticle formulations and prodrugs. These targeting approaches successfully increase the concentration of immunomodulators achieved in the GALT and, more importantly, enhance immunomodulatory effects. Therefore, targeting immunomodulators to GALT represent a promising approach in the treatment of diseases where the immune system is actively involved.

Regulating Inflammatory Immune Response to Atherogenic Antigens Prevents Development and Progression of Atherosclerosis in New Zealand White Rabbits

BACKGROUND

Inflammatory immune response to atherogenic self-antigens plays an important role in the development of atherosclerosis. We evaluated the role of oral tolerance to three peptides in controlling atherosclerosis in New Zealand white rabbits.

METHODS

Peptides derived from apolipoprotein B (ApoB), heat shock protein 60, and outer membrane protein from Chlamydia pneumoniae were expressed as part of the dendroaspin protein scaffold (AHC). Groups of 3-month-old rabbits were dosed orally with purified AHC protein either before the onset of disease or 2 months after inducing atherosclerosis; they were euthanized at the age of 7 months to study disease development and progression.

RESULTS

Oral treatment with AHC resulted in a marked increase in regulatory T cells in the lymphoid organs and reduced the development and progression of atherosclerosis by 48.6% and 28.4%, respectively (P < 0.05). Oral tolerance decreased plaque inflammation, enhanced expression of anti-inflammatory and regulatory markers in the aorta, and attenuated the adaptive immune response to self-antigens. AHC treatment in rabbits with established disease significantly decreased vascular cell adhesion molecule 1 (VCAM-1) (6.2 fold) and monocyte chemoattractant protein-1(MCP-1) (3 fold) expression and reduced the infiltration of macrophages into the aorta. Collagen content and the smooth muscle cell-to-macrophage ratio were higher in treated animals, whereas markers of plaque vulnerability, including matrix metalloproteinase expression, were reduced.

CONCLUSIONS

Our results suggest that oral tolerance to multiantigenic AHC molecule restores the immune balance and induces markers of plaque stability in rabbits.