Basophils and mast cells play critical roles for leukocyte recruitment in IgE-mediated cutaneous reverse passive Arthus reaction

Granzyme B inhibition reduces disease severity in autoimmune blistering diseases

Pemphigoid diseases refer to a group of severe autoimmune skin blistering diseases characterized by subepidermal blistering and loss of dermal-epidermal adhesion induced by autoantibody and immune cell infiltrate at the dermal-epidermal junction and upper dermis. Here, we explore the role of the immune cell-secreted serine protease, granzyme B, in pemphigoid disease pathogenesis using three independent murine models. In all models, granzyme B knockout or topical pharmacological inhibition significantly reduces total blistering area compared to controls. In vivo and in vitro studies show that granzyme B contributes to blistering by degrading key anchoring proteins in the dermal-epidermal junction that are necessary for dermal-epidermal adhesion. Further, granzyme B mediates IL-8/macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity. Clinically, granzyme B is elevated and abundant in human pemphigoid disease blister fluids and lesional skin. Collectively, granzyme B is a potential therapeutic target in pemphigoid diseases.

Allergic inflammation is initiated by IL-33-dependent crosstalk between mast cells and basophils

IgE-primed mast cells in peripheral tissues, including the skin, lung, and intestine, are key initiators of allergen-triggered edema and inflammation. Particularly in severe forms of allergy, this inflammation becomes strongly neutrophil dominated, and yet how mast cells coordinate this type of response is unknown. We and others have reported that activated mast cells--a hematopoietic cell type--can produce IL-33, a cytokine known to participate in allergic responses but generally considered as being of epithelial origin and driving Type 2 immune responses (e.g., ILC2 and eosinophil activation). Using models of skin anaphylaxis, our data reveal that mast cell-derived IL-33 also initiates neutrophilic inflammation. We demonstrate a cellular crosstalk mechanism whereby activated mast cells crosstalk to IL-33 receptor-bearing basophils, driving these basophils to adopt a unique response signature rich in neutrophil-associated molecules. We further establish that basophil expression of CXCL1 is necessary for IgE-driven neutrophilic inflammation. Our findings thus unearth a new mechanism by which mast cells initiate local inflammation after antigen triggering and might explain the complex inflammatory phenotypes observed in severe allergic diseases. Moreover, our findings (i) establish a functional link from IL-33 to neutrophilic inflammation that extends IL-33-mediated biology well beyond that of Type 2 immunity, and (ii) demonstrate the functional importance of hematopoietic cell-derived IL-33 in allergic pathogenesis.

A preclinical study-systemic evaluation of safety on mesenchymal stem cells derived from human gingiva tissue

BACKGROUND

Mounting evidence has shown that a novel subset of mesenchymal stem cells (MSCs) derived from human gingiva referred to as gingival mesenchymal stem cells (GMSCs) displays a greater immunotherapeutic potential and regenerative repair expression than MSCs obtained from other tissues. However, the safety of the use of transplanted GMSCs in humans remains unclear.

METHODS

In this study, we evaluated the safety of GMSCs transplanted into mouse, rat, rabbit, beagle dog, and monkey as well as two animal models of autoimmune diseases.

RESULTS

In short- and long-term toxicity tests, infused GMSCs had no remarkable adverse effects on hematologic and biochemical indexes, particularly on the major organs such as heart, liver, spleen, and kidney in recipient animals. It was also shown that GMSCs were well tolerated in other assays including hemolysis, vascular, and muscular stimulation, as well as systemic anaphylaxis and passive skin Arthus reaction in animal models. GSMC infusion did not cause any notable side effects on animal models of either autoimmune arthritis or lupus. Significantly, GMSCs most likely play no role in genotoxicity and tumorigenesis. The biological features remained stable for an extended period after cell transfer.

CONCLUSIONS

GMSCs are safe in various animal models of autoimmunity, even during active disease episodes, especially in monkeys. This study paves a solid road for future clinical trials of GMSCs in patients with autoimmune and inflammatory diseases.

Intradermal Delivery of Antigens Enhances Specific IgG and Diminishes IgE Production: Potential Use for Vaccination and Allergy Immunotherapy

Skin is protected by a tough but flexible multilayered barrier and is a front line for immune responses against invading particles. For many years now, skin has been a tissue where certain vaccines are injected for the prevention of infectious disease, however, the detailed mechanisms of the skin immune response are not yet well understood. Using thin and small injection needles, we carefully injected OVA into a restricted region of mouse skin, i.e., intradermal (ID), and examined the antibody response in comparison with subcutaneous (SC) injection or epicutaneous patch administration of OVA. Epicutaneous patches induced a high IgE response against OVA, but IgG production was low. High IgG production was induced by both ID and SC injection, moreover, ID injection induced higher IgG production without any adjutants. Furthermore, OVA-specific IgE production was diminished by ID injection. We found that ID injection could efficiently stimulate skin resident DCs, drive Th1-biased conditions and diminish IgE production. The ID injection response was regulated by Langerin+ dermal DCs, because OVA was taken up mainly by these cells and, after transiently deleting them, the IgE response was no longer diminished and IgG1 production was enhanced. We also tested whether ID injection might be an effective allergy treatment by attempting to inhibit ongoing IgE production in mice with experimentally induced high serum IgE levels. Multiple ID injections of OVA were shown to prevent elevation of serum OVA-specific IgE after repeated allergen challenge. In contrast, SC OVA injection could only transiently inhibit the OVA-specific IgE production. These findings indicated that ID injection results in higher induction of antigen-specific IgG, and thus may be useful for vaccine delivery with little or no adjuvant components. Moreover, the observed diminishment of IgE and induction of Th1-biased immune responses suggest that ID may be a useful injection route for allergy immunotherapy.

Basophils Promote Tumor Rejection via Chemotaxis and Infiltration of CD8+ T Cells

Elevated numbers of regulatory T cells (Treg) in patient tumors are known to inhibit efficient antitumor T-cell responses. To study the mechanisms controlling tumor rejection, we assessed different mouse models for Treg depletion. In Foxp3DTR knock-in mice, about 99% Treg depletion was achieved, resulting in complete rejection of transplanted HCmel12 melanomas in a CD8⁺ T-cell-dependent way. In contrast, about 90% Treg depletion obtained in BAC transgenic Foxp3.LuciDTR4 mice failed to induce complete rejection of HCmel12 melanomas, demonstrating that residual Tregs were able to control CD8⁺ T-cell responses against the tumor. Ninety-nine percent of Treg depletion provoked drastic changes in the tumor microenvironment, such as strong infiltration of CD8⁺ T cells and basophils. Intratumoral basophils enhanced CD8⁺ T-cell infiltration via production of chemokines CCL3 and CCL4; antibody-based blocking of these chemokines inhibited CD8⁺ T-cell infiltration. Therapeutic induction of basophilia by IL3/anti-IL3 antibody complexes, combined with transfer of CD8⁺ T cells, resulted in enhanced T-cell infiltration and tumor rejection. Our study identifies a critical role basophils play in tumor rejection and that this role can be exploited for therapeutic intervention. Cancer Res; 77(2); 291-302. ©2016 AACR.

New insights into basophil heterogeneity

Basophils have become increasingly recognized as important innate immune cells that mediate antihelminth immunity and barrier inflammation. Recent discoveries have uncovered previously unrecognized heterogeneity in basophil populations. However, how diversity in basophil regulation and function impacts human disease remains poorly defined. The goal of the present review is to highlight how new insights into basophil heterogeneity can help us to better understand disease pathogenesis and inform the development of new therapeutics.

Involvement of mast cells and proteinase-activated receptor 2 in oxaliplatin-induced mechanical allodynia in mice

The chemotherapeutic agent oxaliplatin induces neuropathic pain, a dose-limiting side effect, but the underlying mechanisms are not fully understood. Here, we show the potential involvement of cutaneous mast cells in oxaliplatin-induced mechanical allodynia in mice. A single intraperitoneal injection of oxaliplatin induced mechanical allodynia, which peaked on day 10 after injection. Oxaliplatin-induced mechanical allodynia was almost completely prevented by congenital mast cell deficiency. The numbers of total and degranulated mast cells was significantly increased in the skin after oxaliplatin administration. Repetitive topical application of the mast cell stabilizer azelastine hydrochloride inhibited mechanical allodynia and the degranulation of mast cells without affecting the number of mast cells in oxaliplatin-treated mice. The serine protease inhibitor camostat mesilate and the proteinase-activated receptor 2 (PAR2) antagonist FSLLRY-NH2 significantly inhibited oxaliplatin-induced mechanical allodynia. However, it was not inhibited by the H1 histamine receptor antagonist terfenadine. Single oxaliplatin administration increased the activity of cutaneous serine proteases, which was attenuated by camostat and mast cell deficiency. Depletion of the capsaicin-sensitive primary afferents by neonatal capsaicin treatment almost completely prevented oxaliplatin-induced mechanical allodynia, the increase in the number of mast cells, and the activity of cutaneous serine proteases. These results suggest that serine protease(s) released from mast cells and PAR2 are involved in oxaliplatin-induced mechanical allodynia. Therefore, oxaliplatin may indirectly affect the functions of mast cells through its action on capsaicin-sensitive primary afferents.

IgE-activated basophils regulate eosinophil tissue entry by modulating endothelial function

Basophils orchestrate eosinophil recruitment during IgE-dependent dermatitis by interacting with inflamed endothelium and producing IL-4. IL-4 in turn induces endothelial VCAM-1 expression, which is required for subsequent eosinophil accumulation.

Vertebrate immunity has evolved a modular architecture in response to perturbations. Allergic inflammation represents such a module, with signature features of antigen-specific IgE and tissue eosinophilia, although the cellular and molecular circuitry coupling these responses remains unclear. Here, we use genetic and imaging approaches in models of IgE-dependent eosinophilic dermatitis to demonstrate a requisite role for basophils. After antigenic inflammation, basophils initiate transmigration like other granulocytes but, upon activation via their high-affinity IgE receptor, alter their migratory kinetics to persist at the endothelium. Prolonged basophil–endothelial interactions, in part dependent on activation of focal adhesion kinases, promote delivery of basophil-derived IL-4 to the endothelium and subsequent induction of endothelial vascular cell adhesion molecule-1 (VCAM-1), which is required for eosinophil accumulation. Thus, basophils are gatekeepers that link adaptive immunity with innate effector programs by altering access to tissue sites by activation-induced interactions with the endothelium.

Diagnosis of Mesobuthus eupeus envenomation by skin test: reverse passive Arthus reaction

While being stung by two large families of scorpions, Buthidae and Scorpionidae have different symptoms and complications, a similar maintenance treatment usually considers as the scorpion species could not be identified easily. Therefore, this study was an attempt to develop an immunologic response for designing a skin sensitivity test that can be used to determine the poisoning. The sensitivity and the specificity of RPA reaction for detecting experimental envenomated mice were evaluated. The inflammatory response for detection of envenomation was obtained by the injection of a solution containing complement, polyelectrolytes and purified monovalent antibodies. As the result, 84.44% sensitivity and 100% specificity recorded 15 min after challenge. Macroscopic findings were also confirmed histologically. No cross-reactions were observed with other species of scorpions and snake venoms. Designed Skin test induced obvious inflammatory reaction without any histological lesions. Besides adding the complement components and polyelectrolyte to the monovalent antibody leads to an increased susceptibility of inflammatory cells in this reaction, resulting in forming a visible inflammation in a short time. According to satisfactory specificity and sensitivity and visible results in about 15 min, non-harmful and cost benefity of reverse passive Arthus test can be used for diagnosis of scorpion envenomation.