Kita, Hirohito

Objective To evaluate eosinophil peroxidase (EPX) as a biomarker for tissue levels of eosinophilia, cytokines, and chemokines within chronic rhinosinusitis (CRS). Methods Twenty‐eight subjects undergoing sinonasal surgery were prospectively enrolled. Ethmoid tissue was analyzed with an in‐house EPX immunoassay and a 48‐plex cytokine‐chemokine array. Clinical severity was assessed using SNOT‐22 and Lund‐Mackay scores. Subjects were grouped as follows: controls, polyp status (CRS with [CRSwNP] and without nasal polyps [CRSsNP]), tissue eosinophilia (eosinophilic CRS [eCRS], non‐eosinophilic CRS [neCRS]), or combinations thereof (eCRSwNP, eCRSsNP, neCRSsNP). eCRS was defined as >10 eosinophils per high power field (HPF). Subjects without CRS or asthma were enrolled as controls. Results EPX was elevated in CRSwNP compared to control ( p = 0.007), in eCRS compared to neCRS ( p = 0.002), and in eCRSwNP along with eCRSsNP compared to neCRSsNP ( p = 0.023, p = 0.015, respectively). eCRS displayed elevated IL‐5 compared to neCRS ( p = 0.005). No significant differences in EPX or IL‐5 were observed between eCRSwNP and eCRSsNP. IL‐5 was elevated in eCRSwNP ( p = 0.019) compared neCRSsNP. Area under the receiver operator characteristic curve was 0.938 (95% CI, 0.835–1.00) for EPX and tissue eosinophilia, with an optimal cut‐point of 470 ng/mL being 100% specific and 81.25% sensitive for tissue eosinophilia. Linear regression revealed a strong correlation between EPX and IL‐5 (R 2 = 0.64, p < 0.001). Comparing EPX and IL‐5, only EPX displayed significant correlation with SNOT‐22 ( p = 0.04) and Lund‐Mackay score ( p = 0.004). Conclusion EPX is associated with tissue eosinophilia in CRS patients regardless of polyp status. EPX correlates with IL‐5 and could be potentially considered a biomarker for anti‐IL‐5 therapies. Level of Evidence 3 Laryngoscope , 134:69–78, 2024

Exposure of human bronchial epithelial cells (hBECs) and mouse airways to allergens from the fungus Alternaria alternata triggers the release of alarmin signaling molecules including ATP, IL-33 and DNA fragments. The goal of this study was to determine the mechanisms that regulate release of genomic DNA fragments and how extracellular DNA (eDNA) contributes to type 2 immunity. Treatment of hBECs with Alternaria extract induces oxidative stress, which leads to ATP release and uptake of Ca2+ following activation of P2X receptors. DNA release was dependent on a sustained increase in intracellular [Ca2+], which stimulates cleavage of caspase 3 by the proprotein convertase enzyme furin, resulting in activation of caspase 3 and ultimately nuclear DNA fragmentation as shown in comet assays. Some of the fragmented DNA was released into the media under conditions where barrier function of the epithelium was maintained, and nuclear and plasma membranes remained intact. Alternaria-induced DNA release was detected within 30 minutes following exposure, reached its peak at 4 hours and ceased after 12 hours. Pretreatment of hBECs with a calpain inhibitor resulted in continued DNA release and loss of cell viability by 24 hours. This result suggested that calpain activity contributed to termination of Alternaria-evoked DNA release. In mice, intranasal administration of Alternaria extract produced release of DNA fragments into bronchoalveolar lavage (BAL) fluid over a similar time course as observed in hBECs. In caspase 3 deficient mice however, DNA release into BAL fluid was significantly reduced. Furthermore, Alternaria-induced type 2 immune responses were suppressed following pretreatment with a DNA scavenger. Conversely, intranasal administration of mouse genomic DNA with Alternaria amplified IL-5 and IL-13 secretion into BAL fluid while DNA alone had no effect. These findings indicate that DNA release from the airway epithelium is a regulated process involving noncanonical activation of caspase 3 to produce DNA fragmentation and calpain activity, which appears to be essential for the termination of DNA release. Moreover in airways, eDNA appears to function as a secondary alarmin that acts on immune cells to enhance type 2 immunity. This work was supported by grants from the NIH (AI128729 and AI169530) to HK and SMO. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract Food allergy, such as peanut allergy can cause life-threatening anaphylaxis. While T follicular helper (Tfh) cells play a major role in production of allergen-specific IgE and IgG antibodies, the immunologic mechanisms that regulate the production of antibodies that mediate anaphylaxis are not well understood. While PD-1 is highly expressed on Tfh cells, our knowledge is limited regarding the role of the molecule in Tfh cells. Thus, the objective of this study was to investigate the roles of PD-1 in allergic immune responses using a mouse model of peanut allergy. Naïve wild-type mice were exposed to peanut flour intranasally (i.n.) and then challenged by intraperitoneal (i.p.) injection of peanut extract. The mice exposed i.n. to peanut flour produced peanut-specific IgE and IgG antibodies and developed anaphylaxis when challenged i.p. with peanut extract. PD-1 blockade with anti-PD-1 treatment Tfh and germinal center B cell numbers in mice exposed to peanut flour. Nonetheless, anti-PD-1 or anti-PD-L1 fully protected mice from anaphylaxis. Anti-PD-1 or genetic deficiency of PD-1 in CD4+ T cells reduced and increased levels of peanut-specific IgE and IgG, respectively. Anti-PD-1 promoted production of low-affinity IgE and IgG antibodies with no effect on high-affinity antibodies. By passive cutaneous anaphylaxis, peanut-specific antibodies generated in anti-PD1 treated mice failed to induce anaphylaxis, and plasma from these mice prevented anaphylaxis. Therefore, blockade of the PD-1 pathway is protective against allergic immune responses. The interaction between Tfh cells and B cells may play a pivotal role in controlling antibody quality and clinical manifestation of allergic diseases.

Abstract CD9 is a cell surface glycoprotein belonging to the transmembrane 4 superfamily. In this report, we demonstrate that cross-linking CD9 with different forms of mAb activates distinct functions of human eosinophils. Anti-CD9 mAb (clone ALB6) immobilized onto tissue culture plates induced eosinophil degranulation. This effect of anti-CD9 mAb (clone ALB6) was unique because other immobilized clones of anti-CD9 mAb (clones FMC56 and ML13) or anti-HLA Class I mAb failed to induce degranulation. In addition, neutrophil degranulation was not provoked by the immobilized clone ALB6, consistent with a lack of expression of CD9 on neutrophils. Eosinophil degranulation induced by anti-CD9 mAb (clone ALB6) was abolished by pretreatment of eosinophils with anti-CD18 mAb, suggesting that beta2 integrins are involved in the reaction. In contrast to the results with immobilized clones, all clones of anti-CD9 mAb in soluble form enhanced eosinophil survival. This enhanced survival was inhibited by anti-granulocyte-macrophage-CSF (GM-CSF) mAb, suggesting that autocrine production of GM-CSF by eosinophils mediated the enhanced survival. In fact, by ELISA and RT-PCR, GM-CSF protein and mRNA were detected in supernatants and cell lysates of eosinophils stimulated by soluble anti-CD9 mAb, but not by immobilized mAb. These results indicate that CD9 serves as a molecule that delivers stimulation signals on eosinophils. The eosinophil's cellular responses may differ and be dependent on the manner of receptor ligation.

Abstract We investigated whether human IgM antibody, B7-DCXAb, which binds to B7-DC and enhances DCs' antigen uptake and retention, migration, and cytokine production, improves the efficacy of allergen immunotherapy. Mice were sensitized by intraperitoneal injection of OVA or house dust mite (HDM) antigens plus alum and then treated by intravenous B7-DCXAb injection intranasal or sublingual administration of antigen. OVA-sensitized mice developed anti-OVA IgE and IgG1, Th2-type splenocyte responses to OVA; marked airway eosinophilic inflammation was observed after intranasal OVA challenge. When these mice were treated by intravenous B7-DCXAb plus intranasal OVA, anti-OVA IgE and IgG1 decreased by 75~95% within 1 week; this decrease persisted for &gt;8 weeks. Anti-OVA IgG2a decreased transiently. Splenocyte production of IL-4, IL-5, and IL-13 in response to OVA was abolished; no increases in IFN-g or IL-17 were noted. In OVA-challenged mice, airway eosinophilia and lung levels of IL-4, IL-5 and IL-13 were reduced by &gt;90%. Immunotherapeutic effects were also observed with intravenous B7-DCXAb plus sublingual OVA, but not with intravenous B7-DCXAb alone. Furthermore, HDM-sensitized mice were treated successfully by intravenous B7-DCXAb plus intranasal HDM. B7-DCXAb injection plus mucosal administration of antigen effectively treats allergic responses and may provide novel strategy for allergen immunotherapy.

Abstract Innate lymphoid cells (ILCs) are emerging as important effector cells in innate immunity and tissue homeostasis. Group 2 ILCs (ILC2s) have been identified in organs and tissues, such as adipose tissue, small intestine, lungs and skin, where they are involved in helminth immunity, type 2 immune responses, and tissue pathology and recovery. Using flow cytometry, we identified ILC2s in mouse uteri and confirmed IL-5, but not IL-13, production in response to IL-33 both in vivo and in vitro. Furthermore, intraperitoneal administration of IL-33 induced recruitment of activated ILC2s to uteri as well as to lungs. To investigate the possibility that uterine ILC2s might play a role in maintaining a healthy pregnancy, we mated ST2-/- females (on a Balb/c background) with ST2-/-, MHC-matched Balb/c and MHC-mismatched C57B6 males (ST2 is the IL-33 receptor). Balb/c, C57B6 and Balb/c x C57B6 pairs were used as controls. Litter sizes were not significantly different among the pairings. We defined viable pups as those still alive 24 hours after parturition. Total numbers of non-viable pups, percent of litters with at least one non-viable pup and percent of non-viable pups per litter were significantly increased in ST2-/- x C57B6 pairs when compared to control pairs. Thus, IL-33-responsive ILC2s are present in murine uterine tissue and may play roles in successful reproduction.

Abstract The cyclooxygenase (COX) metabolic pathway has regulatory functions in immune responses and inflammation. However, the effect of the COX pathway on innate airway inflammation induced by protease-containing allergens such as Alternaria alternata is not fully defined. Here we show that COX inhibition augmented innate lung type 2 responses after repeated airway exposures to Alternaria extract in mice. We treated wild type BALB/c and IL-33 KO mice with either the COX inhibitor indomethacin or vehicle in drinking water and challenged mice intranasally with Alternaria extract for 4 consecutive days to induce innate lung inflammation. We found that indomethacin significantly increased the numbers of group 2 innate lymphoid cells (ILC2) and IL-5+IL-13+ ILC2 in the lung. Indomethacin also increased type 2 cytokine (IL-5 and IL-13) responses, the percentages of eosinophils, and mucus production in the lung. IL-33 is required for Alt-induced lung ILC2 responses, and indomethacin did not change IL-5 and IL-13 expression in IL-33 KO mice. Consistently, indomethacin increased the release of IL-33 in bronchoalveolar lavage fluid after Alternaria challenge, suggesting that more IL-33 was available for ILC2 activation. Indomethacin also increased reactive oxygen species (ROS) production in the lung, providing a possible mechanism for the increased IL-33 release. Although contrasting effects of PGD2 and PGE2/PGI2 on ILC2 responses have been previously reported, the overall effect of COX pathway on ILC2 function is inhibitory in Alternaria extract-induced airway innate type 2 responses.

Abstract The objective of this study was to test the hypothesis that the increasing global incidence of allergy and atopy are due in part to improved hygiene and decreased microbial exposure. We have adopted a novel mouse model of normalized microbial exposure to test the impact of immune experience on subsequent responses to airway allergens. In this model, specific pathogen free (SPF) B6 mice are cohoused with mice from pet stores and become “dirty” – many commensals and pathogens are transmitted through cohousing and influence the immune cell populations systemically and in the lungs. We treated mice intranasally with a single dose of A. alternata fungal extract (Alt) and assessed production of type 2 cytokines. IL5 and IL13 levels in the lungs and bronchoalveolar lavage fluid were dramatically elevated by Alt in SPF mice but were not significantly increased by Alt in dirty mice. Type 2 innate lymphoid cells (ILC2) are the cells responsible for IL5 and IL13 after acute Alt treatment, and interestingly the number of lung ILC2 was unaltered by cohousing and their activation status appeared similar in both housing conditions. We treated mice with recombinant IL33, the alarmin released by lung epithelial cells in response to allergens, and the results suggest an impaired response to IL33 by dirty lung ILC2. In a repeated Alt exposure model, ILC2 cells expanded in SPF lungs and recruited eosinophils, neutrophils, and T cells. Most dirty mouse lungs contained these cell populations at steady state but were only modestly recruited with repeated Alt exposure. Lung function experiments are in progress. This study suggests that increased microbial exposure leads to more type-2 associated immune cells in the lungs, however responses to airway allergens are dampened.

Abstract Human eosinophils have been reported to express both the mRNA and protein for the high affinity IgE receptor (FcεRI); it is speculated that this receptor plays a role in eosinophil mediator release in allergic diseases. However, questions still remain. How much of the FcεRI protein is actually expressed on the cell surface of the eosinophil? If they are present, are these IgE receptors associated with effector functions of eosinophils? To address these issues, we studied blood eosinophils from patients with ragweed hay fever. A high level of low affinity IgG receptor (FcγRII, CD32), but no expression of FcεRI, was detectable on the eosinophil surface by standard FACS analysis. However, after in vitro sensitization with biotinylated chimeric IgE (cIgE), cell-bound cIgE was detected by PE-conjugated streptavidin. This cIgE binding was partially inhibited by anti-FcεRI mAb, suggesting that eosinophils do express minimal amounts of FcεRI detectable only by a sensitive method. Indeed, FACS analysis of whole blood showed that eosinophils express ∼0.5% of the FcεRI that basophils express. When stimulated with human IgE or anti-human IgE, these eosinophils did not exert effector functions; there was neither production of leukotriene C4 or superoxide anion nor any detectable degranulation response. In contrast, eosinophils possessed membrane-bound human IgG and showed functional responses when stimulated with human IgG or anti-human IgG. Thus, IgG and/or cytokines, such as IL-5, appear to be more important for eosinophil activation in allergic diseases than IgE.

Abstract Peanut allergies are life-long diseases that cause severe anaphylactic responses to affected individuals. Oral ingestion of peanut products prevents infants from developing peanut allergy. However, little information is currently available regarding the immunologic mechanisms for this protection. Therefore, the goal of this project was to establish an oral tolerance model to peanut allergy in mice and to determine the immunologic mechanisms. Naïve BALB/c mice that were exposed intranasally (i.n.) to peanut flour (PNf) developed peanut allergy as demonstrated by increased serum levels of IgE antibody as well as acute anaphylactic response when challenged with peanut extract. When mice were fed peanut butter (PNB) prior to i.n PNf exposure, they were protected from developing peanut allergy; these mice showed decreased serum levels of IgE antibody and lacked anaphylactic response. T follicular helper (Tfh) cells and germinal center (GC) B cells were decreased in lung draining lymph nodes of mice fed PNB. Furthermore, scRNSseq revealed 2 distinct CD4+ T cell subpopulations that are increased in those protected mice. CTLA-4, a checkpoint molecule, was highly expressed in one of these subpopulations. Systemic administration of a CTLA-4 blocking antibody to mice fed PNB increased the numbers of Tfh cells and GC B cells and increased serum levels of IgE antibody. Finally, anti-CTLA-4 reversed the clinical efficacy of oral PNB administration, resulting in manifestation of acute anaphylaxis when challenged with peanut extract. Thus, oral administration of peanut product(s) prevents development of peanut allergy in mice. CTLA4+CD4+ T cells likely play a pivotal role in this process by regulating the development of Tfh cells.