Regulation of IgE production and airway reactivity by CD4⁻CD8⁻ regulatory T cells

The Comparation of Intraperitoneal Injection and Nasal-only Delivery Allergic Rhinitis Model Challenged With Different Allergen Concentration

BACKGROUND

Predominantly, 2 animal models are used for allergic rhinitis (AR), which are established by intraperitoneal (IP) injection plus local challenge and nasal-only delivery. The differences between these 2 models are not fully understood. Moreover, dose-response relationship to allergens remains unclear.

METHODS

In this study, mice were sensitized by nasal drops (without adjuvant, once daily for 9 weeks) to set up a nasal-only delivery AR model. Five different doses of ovalbumin (OVA) nasal drops were served to explore the dose-response to allergens. Allergic symptoms, serum antibodies (IgE, IgG2a, and IgG1), spleen supernatant and nasal lavage fluid (NALF) cytokines (IL-4, IL-5, and IFN-r), and infiltrated eosinophils of the nasal mucosa were observed.

RESULTS

The allergic symptoms, serum antibodies, cytokines, and infiltrated eosinophils were significantly higher in the high OVA concentration compared with those of the control group. Different OVA concentrations associated with the severity of allergy. Within a certain concentration range, OVA concentration positively related to the severity of symptoms, IgE antibody level, and Th2 bias. Meanwhile, serum antibodies (IgE and IgG1) and cytokines (IL-4, IL-5 in spleen and IL-4 in NALF) were significantly higher in the classical IP injection group than in the nasal drip groups.

CONCLUSION

The IP injection model and the nasal-only delivery model are 2 typical models for AR that causes a different immune response. A positive dose-response relationship in the nasal-only delivery model is observed from 25 mg/mL to 0.025 mg/mL.

Food allergen-specific sublingual immunotherapy modulates peripheral T cell responses of dogs with adverse food reactions

Food allergen-specific sublingual immunotherapy (FA-SLIT) is a novel, safe and effective approach in dogs with adverse food reactions (AFR) to reduce their clinical symptoms. However, little is known about the specific immune components which mediate this reduction in clinical symptoms. In humans, regulatory T cells seem to play an important role in this desensitisation process. Here, we investigated changes in peripheral T cell responses of dogs with AFR upon FA-SLIT. Five dogs received a dose escalation of FA-SLIT over a six-month period. An oral food challenge was performed at the beginning and end of the study to assess the efficacy of the FA-SLIT. Using in vitro allergen-recall assays, we assessed the proliferation of T cell subsets before and at the end of the treatment. FA-SLIT significantly increased the percentage of proliferating CD4-CD8- double-negative (DN) T cells, while the percentage of allergen-specific CD4-CD8+ and CD4+CD8+ double-positive (DP) T cells decreased upon treatment. These findings indicate that sublingual immunotherapy in dogs activates DN T cells, which might be important for the desensitisation of dogs with adverse food reactions. However, further research is needed to corroborate these findings and to further elucidate the mechanism of action of FA-SLIT in dogs with AFR.

Dihydroartemisinin Ameliorated Ovalbumin-Induced Asthma in Mice via Regulation of MiR-183C

BACKGROUND The purpose of the present study was to investigate the function and mechanism of dihydroartemisinin (DHA) in treating ovalbumin-induced asthma in BALB/c mice. MATERIAL AND METHODS Thirty female BALB/c mice were randomly separated into 3 groups: the control group, the asthma model group stimulated by ovalbumin (OVA group), and the DHA treatment group (DHA group). The therapeutic effects and potential pharmacological mechanisms of DHA were specifically clarified by examining its effects on asthma-related phenomena, such as body weight, lung function, cell counts in bronchoalveolar lavage fluid (BALF), and hemotoxin and eosin staining. In addition, the expression of inflammatory factors was checked by enzyme-linked immunosorbent assay kits, and fractions of Th17 cells were detected by FACS analysis. Moreover, the downstream molecular pathway of IL-6/Stat3 (interleukin-6/signal transducer and activator of transcription 3) and expression of miR-183C was investigated by western blot and/or quantitative real-time polymerase chain reaction. Luciferase assay was used to reveal the function of miR-183C on the transcriptional regulation of Foxo1 (forkhead box O). RESULTS DHA administration significantly relieved the severity of the asthma through its effect on body weight, survival rate, and airway pressure. DHA was able to ameliorate lung damage in terms of pathological morphology and it reduced the percentage of helper T 17 (Th17) cells and the secretion of cytokines. As a result, the activity of the IL-6/Stat3 pathway was inhibited by DHA. In addition, the adoption of DHA decreased the expression of miR-183C but increased the expression of the transcription factor Foxo1. CONCLUSIONS Our results suggest that the therapeutic effects of DHA on asthma are partially realized via the regulation of miR-183C and IL-6/Stat3 pathway.

Effects of ceftriaxone-induced intestinal dysbacteriosis on regulatory T cells validated by anaphylactic mice

Both probiotics and pathogens in the human gut express pathogen-associated molecular patterns (PAMPs) and die with the release of endotoxin and bacterial DNA, which can stimulate our immune system and cause immune reaction. However, it's interesting and fascinating to address why the normal intestinal flora will not generate immunological rejection like the pathogen does. By investigating the changes in cells and molecules relevant to immune tolerance in mice with ceftriaxone-induced dysbacteriosis, our study discovered that both the Evenness indexes and Shannon Wiener index of intestinal flora showed a decrease in dysbacteriosis mice. Moreover, the proportion of αβ⁺TCR⁺CD3⁺CD4^-CD8^- cells, CD3⁺γδTCR⁺ cells and CD4⁺CD25⁺FoxP3⁺ cells in the Peyer's patches (PPs), mesenteric lymph nodes (MLNs) and spleen (SP) and the level of TGF-β1, IL-2, IL-4 and IL-10 in the serum also changed. Intestinal dysbacteriosis in an asthma murine model resulted in enhancement of immunologic response to the allergen ovalbumin (OVA), which was an agent that aggravates asthma symptoms. In summary, it is integral to maintain a certain amount or variety of intestinal microflora for regulatory T cells to act in averting hypersensitivity.

Dietary wheat amylase trypsin inhibitors exacerbate murine allergic airway inflammation

BACKGROUND

Wheat amylase trypsin inhibitors (ATI) are dietary non-gluten proteins that activate the toll-like receptor 4 on myeloid cells, promoting intestinal inflammation.

AIM OF THE STUDY

We investigated the effects of dietary ATI on experimental allergic airway inflammation.

METHODS

Mice on a gluten and ATI-free diet (GAFD), sensitized with PBS or ovalbumin (OVA) and challenged with OVA, were compared to mice on a commercial standard chow, a gluten diet naturally containing ~ 0.75% of protein as ATI (G+AD), a gluten diet containing ~ 0.19% of protein as ATI (G-AD) and a GAFD with 1% of protein as ATI (AD). Airway hyperreactivity (AHR), inflammation in bronchoalveolar lavage (BAL) and pulmonary tissue sections were analyzed. Allergic sensitization was assessed ex vivo via proliferation of OVA-stimulated splenocytes.

RESULTS

Mice on a GAFD sensitized with PBS did not develop AHR after local provocation with methacholine. Mice on a GAFD or on a G-AD and sensitized with OVA developed milder AHR compared to mice fed a G+AD or an AD. The increased AHR was paralleled by increased BAL eosinophils, IL-5 and IL-13 production, and an enhanced ex vivo splenocyte activation in the ATI-fed groups.

CONCLUSIONS

Dietary ATI enhance allergic airway inflammation in OVA-challenged mice, while an ATI-free or ATI-reduced diet has a protective effect on AHR. Nutritional wheat ATI, activators of intestinal myeloid cells, may be clinically relevant adjuvants to allergic airway inflammation.

Nutritional Wheat Amylase-Trypsin Inhibitors Promote Intestinal Inflammation via Activation of Myeloid Cells

BACKGROUND & AIMS

Wheat amylase-trypsin inhibitors (ATIs) are nutritional activators of innate immunity, via activation of the toll-like receptor 4 (TLR4) on myeloid cells. We aimed to characterize the biologic activity of ATIs in various foods and their effect on intestinal inflammation.

METHODS

We selected 38 different gluten-containing and gluten-free products, either unprocessed (such as wheat, rye, barley, quinoa, amaranth, soya, lentils, and rice) or processed (such as pizza, pasta, bread, and biscuits). ATIs were extracted and their biological activities determined in TLR4-responsive mouse and human cell lines. Effects of oral ATIs on intestinal inflammation were determined in healthy C57BL/6 mice on a gluten-free or ATI-free diet and in mice given low-level polyinosinic:polycytidylic acid or dextran sodium sulfate to induce colitis. Parameters of innate and adaptive immune activation were determined in duodenum, ileum, colon, and mesenteric lymph nodes.

RESULTS

Modern gluten-containing staples had levels of TLR4-activating ATIs that were as much as 100-fold higher than in most gluten-free foods. Processed or baked foods retained ATI bioactivity. Most older wheat variants (such as Emmer or Einkorn) had lower bioactivity than modern (hexaploid) wheat. ATI species CM3 and 0.19 were the most prevalent activators of TLR4 in modern wheat and were highly resistant to intestinal proteolysis. Their ingestion induced modest intestinal myeloid cell infiltration and activation, and release of inflammatory mediators-mostly in the colon, then in the ileum, and then in the duodenum. Dendritic cells became prominently activated in mesenteric lymph nodes. Concentrations of ATIs found in a normal daily gluten-containing diet increased low-level intestinal inflammation.

CONCLUSIONS

Gluten-containing cereals have by far the highest concentrations of ATIs that activate TLR4. Orally ingested ATIs are largely resistant to proteases and heat, and increase intestinal inflammation by activating gut and mesenteric lymph node myeloid cells.

Analysis of allergic immune responses in humanized mice

Nowadays, more than 25% of the population in industrial countries are affected by IgE-mediated (atopic) allergic diseases such as allergic rhinitis, asthma and atopic eczema. Due to intensive research on basis of in vitro studies with human immune cells and different murine in vivo models of allergy fundamental mechanisms of allergic immune responses have been elucidated during the last years. However, human studies are restricted and the immune system of mice differs from the human immune system in several aspects so that the transferability of experimental results from mice to men is limited. Humanized mice represent a new tool to analyze the interaction of human immune cells under physiological conditions as far as possible, particularly to test novel therapeutic strategies. This review summarizes the impact of humanized mouse models for the investigation and treatment of allergic diseases.