Itaconate was initially identified as an antimicrobial compound produced by myeloid cells. Beyond its antimicrobial role, itaconate may also serve as a crucial metabolic and immune modulator. We therefore examined the roles of aconitate decarboxylase 1 (Acod1) and itaconate in house dust mite (HDM)-sensitized and -challenged mice, a model of T helper 2 (Th2)-driven allergic airways disease. HDM treatment induced lung Acod1 mRNA expression and bronchoalveolar lavage (BAL) itaconate levels in wild-type C57BL/6 mice. Acod1 knockout mice (Acod1-KO) with negligible BAL itaconate showed heightened HDM-induced type 2 cytokine expression, increased serum IgE, and enhanced recruitment of Th2 cells in the lung, indicating a shift towards a more pronounced Th2 immune response. Acod1-KO mice also showed increased eosinophilic airway inflammation and hyperresponsiveness. Experiments in chimeric mice demonstrated that bone marrow from Acod1-KO mice is sufficient to increase type 2 cytokine expression in wild-type mice, and that restitution of bone marrow from wild type mice attenuates mRNA expression of Th2 cytokines in Acod1-KO mice. Specific deletion of Acod1 in lysozyme-secreting macrophages (LysM-cre+Acod1flox/flox) recapitulated the exaggerated phenotype observed in whole-body Acod1-KO mice. Adoptive transfer of Acod1-KO bone marrow-derived macrophages also increased lung mRNA expression of Th2 cytokines. In addition, treatment of Th2-polarized CD4 cells with itaconate impeded Th2 cell differentiation, as shown by reduced expression of Gata3 and decreased release of IL-5 and IL-13. Finally, public datasets of human samples show lower Acod1 expression in subjects with allergic asthma, consistent with a protective role of itaconate in asthma pathogenesis. Together, these data suggest that itaconate plays a protective, immunomodulatory role in limiting airway type 2 inflammation after allergen challenge by attenuating T cell responses.

BACKGROUND: Subcutaneous immunotherapy (SCIT) can induce systemic reactions (SRs) in certain patients, but the underlying mechanisms remain to be fully elucidated.
METHODS: AR patients who were undergoing standardized HDM SCIT (Alutard, ALK) between 2018 and 2022 were screened. Those who experienced two consecutive SRs were included in the study group. A control group was established, matched 1:1 by gender, age, and disease duration with the study group, who did not experience SRs during SCIT. Clinical and immunological parameters were recorded and analyzed both before SCIT and after 1 year of treatment.
RESULTS: A total of 161 patients were included, with 79 (49.07%) in the study group. The study group had a higher proportion of AR combined asthma (26.8% vs. 51.8%, p < 0.001) and higher levels of sIgE to HDM and HDM components (all p < .001). Serum IL-4 and IL-13 levels in the study group were higher than those in the control group (p < .05). The study group received a lower maintenance dosage of HDM extracts injections than control group due to SRs (50000SQ vs. 100000SQ, p < .05). After 1 year of SCIT, the VAS score, the lung function parameters of asthmatic patients over 14 years old significantly improved in both groups (all p < .05). After a 7-day exposure to 20 μg/mL HDM extracts, the percentages of Th1, Th17, Tfh10, and Th17.1 in PBMCs decreased, while the Tfh13 cells significantly increased in the study group (p < .05).
CONCLUSIONS: The type 2 inflammatory response is augmented in HDM-induced AR patients who experienced SRs during SCIT. Despite this, SCIT remains effective in these patients when administered with low-dosage allergen extracts.

House dust mite (HDM) allergen immunotherapy (AIT) has an established role in the treatment of perennial allergic rhinitis (AR) and allergic asthma (AA) triggered by HDM sensitization. We aimed to identify all double-blind, randomized, placebo-controlled trials of HDM AIT for the treatment of AR and AA in humans and to summarize the evidence for AIT products that are currently manufactured and available for clinical use. A total of 56 eligible double-blind, randomized, placebo-controlled trials of HDM AIT for the treatment of AA and/or AR in humans fit the inclusion criteria and investigated a total of 14 commercial AIT products; together, the 56 studies enrolled a total of 14,619 patients. Of the 56 studies, 39 studies investigated the current manufacturer-recommended maintenance dose (MRMD) of the product, and 17 investigated other doses. We identified 39 studies (12,539 patients randomized) for 8 sublingual immunotherapy (SLIT) products and 17 studies (2,080 patients randomized) for subcutaneous immunotherapy products. For AR, 3 products, the ALK 12 standardized-quality (SQ-HDM) SLIT tablet, the ALK 6 SQ-HDM tablet, and the SG 300 index of reactivity SLIT tablet, had both dose-finding studies (DFSs) and phase III definitive studies (DSs) to demonstrate efficacy of the MRMD of the product. For AA, 2 products, the ALK 12 SQ-HDM SLIT tablet and the ALK 6 SQ-HDM tablet, had both DFSs and DSs for the MRMD. No subcutaneous immunotherapy product had a paired DFS and DS supporting the MRMD. A total of 30 studies of products no longer commercially manufactured were excluded. This study will help to inform clinical care and product selection for the treatment of HDM-induced AR and AA.

BACKGROUND: Sublingual immunotherapy (SLIT) for perennial allergic rhinitis (AR) has not been extensively studied in preschoolers. We investigated the efficacy and safety of house dust mite (HDM) SLIT-tablet for children aged 1-4 years.
METHODS: Children aged 1-4 years with AR were divided into SLIT (n = 22) and control (n = 12) groups based on their guardians\' preferences. The SLIT group received a daily dose of 10,000 JAU of HDM SLIT-tablet for 12 months, whereas the control group received symptomatic treatment only.
RESULTS: The baseline median age was 41 and 34 months in the SLIT and control groups, respectively, and the median AR symptom score was 4 for both groups. Compared with baseline, the AR symptom score had decreased significantly in the SLIT group after 12 months (score: 3, p = .002), whereas it tended to increase in the control group (score: 6, p = .08). Adverse reactions to SLIT were mild and occurred in eight patients (36%). In the SLIT group, Dermatophagoides (D.) farinae-specific IgE (sIgE) levels increased during the first 6 months and decreased to baseline levels at 12 months. In the control group, D. farinae-sIgE levels had increased significantly at 12 months compared to baseline (p = .01). D. farinae-specific IgG4 and HDM IgE-blocking factor levels were significantly increased at 12 months compared to baseline in the SLIT group only (p < .001). A lower wheezing frequency was seen in the SLIT group (0.3%) compared to the control group (0.7%).
CONCLUSIONS: This pilot study demonstrated the efficacy, safety, and immunomodulatory effects of HDM SLIT-tablet in preschoolers with AR.

Epidemiological data suggest that atopic diseases begin in early life and that most cases present clinically during early childhood. The diseases are highly prevalent and increase as communities adopt western lifestyles. Disentangling the pathophysiological mechanisms leading to disease debut is necessary to identify beneficial/harmful exposures so that successful prevention and treatment can be generated. The objective of this review is to explore the definition of atopy and mechanisms of atopic diseases, and to investigate the importance of environmental factors in early life, prior to disease development. First, the distribution of sIgE levels in children is investigated, as this is one of the main criteria for the definition of atopy. Thereafter, it is explored how studies of parental atopic status, sensitization patterns, and early debut and severity of atopic dermatitis have substantiated the theory of an early-life window of opportunity for intervention that precedes the development of atopic diseases in childhood. Then, it is examined whether early-life exposures such as breastfeeding, dogs, cats, and house dust mites in the home perinatally constitute important influencers in this crucial time of life. Finally, it is discussed how these findings could be validated in randomized controlled trials, which might prepare the ground for improved diagnostics and prevention strategies to mitigate the current atopic pandemic.

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The aim was to evaluate the prediction of house dust mite allergy in children diagnosed with allergic disease based on their skin moisture and sebum levels. This is a case-control study including children with asthma, allergic rhinitis (AR), and atopic dermatitis (AD) and a healthy control group. The participants\' skin moisture and sebum levels were measured non-invasively using a digital device. A total of 421 patients and 143 healthy children were included. The median value of skin moisture percentage was statistically significantly lower in asthma, AR, and AD patients compared to the control group (p < 0.001 for each). The median value of skin sebum percentage was significantly lower in asthma and AD patients compared to the control group (p = 0.002 and p = 0.003, respectively). ROC analysis was performed to assess the predictive value of skin moisture percentage for house dust mite allergy in respiratory allergic diseases (asthma and AR) and AD separately. Using a cut-off point of 35.5% for skin moisture in asthma and AR patients, the sensitivity and specificity were 81.3% and 56.5%, respectively. Although the specificity is low, the high sensitivity value is promising. The non-invasive measurement of skin sebum and moisture could provide convenience to clinicians in the diagnosis and management of allergic diseases.

BACKGROUND: House dust mite (HDM) sensitisation can contribute to the development of allergic rhinoconjunctivitis (AR) or allergic asthma (AA). As treatment, allergen immunotherapy (AIT) is a promising approach, since it aims building immunotolerance against allergens, therewith establishing long-term efficacy. The evaluation of AIT has been investigated in many randomised controlled trials, whereas few real-world evidence studies are available.
METHODS: We used data from the longitudinal prescription data base IQVIA™ LRx. Data on initial AIT prescriptions against HDM from January 2009 to December 2013 was analysed regarding treatment (subcutaneous AIT with either depigmented polymerised allergen extract [dSCIT] or other allergens [oSCIT], or sublingual immunotherapy [SLIT]) and treatment duration. Treatment groups were compared with a control group of AR patients not receiving AIT. Data on symptomatic medication was collected until February 2017 and progression of AR and AA was compared.
RESULTS: Data of 7260 patients with AIT prescriptions and of 21,780 control patients was analysed. AIT was associated with a significant decrease of AR medication intake compared with control (dSCIT: -34.0%, p < 0.0001; oSCIT: -25.7%, p < 0.0001; SLIT: -37.7%, p = 0.0026). In asthmatics, SCIT was associated with a significant decrease of asthma medication compared with control (dSCIT: -45.2%, p < 0.0001; oSCIT: -32.9%, p < 0.0001). Further, a significantly reduced likelihood for onset of asthma medication was demonstrated in patients treated with SCIT compared with controls (dSCIT OR: 0.759, p = 0.0476; oSCIT OR: 0.815, p = 0.0339).
CONCLUSIONS: Real-world data analyses indicate that AIT, particularly given via a subcutaneous route, reduces the need of medication against AR and AA and might delay the onset of asthma medication in patients with AR.

UNASSIGNED: Environmental exposures and experimental manipulations can alter the ontogenetic composition of tissue-resident macrophages. However, the impact of these alterations on subsequent immune responses, particularly in allergic airway diseases, remains poorly understood. This study aims to elucidate the significance of modified macrophage ontogeny resulting from environmental exposures on allergic airway responses to house dust mite (HDM) allergen.
UNASSIGNED: We utilized embryonic lineage labeling to delineate the ontogenetic profile of tissue-resident macrophages at baseline and following the resolution of repeated lipopolysaccharide (LPS)-induced lung injury. We investigated differences in house dust mite (HDM)-induced allergy to assess the influence of macrophage ontogeny on allergic airway responses. Additionally, we employed single-cell RNA sequencing (scRNAseq) and immunofluorescent staining to characterize the pulmonary macrophage composition, associated pathways, and tissue localization.
UNASSIGNED: Our findings demonstrate that the ontogeny of homeostatic alveolar and interstitial macrophages is altered after the resolution from repeated LPS-induced lung injury, leading to the replacement of embryonic-derived by bone marrow-derived macrophages. This shift in macrophage ontogeny is associated with reduced HDM-induced allergic airway responses. Through scRNAseq and immunofluorescent staining, we identified a distinct subset of resident-derived interstitial macrophages expressing genes associated with allergic airway diseases, localized adjacent to terminal bronchi, and diminished by prior LPS exposure.
UNASSIGNED: These results suggest a pivotal role for pulmonary macrophage ontogeny in modulating allergic airway responses. Moreover, our findings highlight the implications of prior environmental exposures in shaping future immune responses and influencing the development of allergies. By elucidating the mechanisms underlying these phenomena, this study provides valuable insights into potential therapeutic targets for allergic airway diseases and avenues for further research into immune modulation and allergic disease prevention.

Objective:Neosensitizations may be occur during the allergen specific immunotherapy（AIT） due to the differences between allergen vaccine\'s content and a patient\'s molecular sensitization profile. This study investigates whether AIT with HDM extract changes the sensitization profile, whether de novo sensitization occurs, and the clinical importance of the neosensitization. Methods:Fifty-three patients with HDM allergic rhinitis ,with/without asthma, patients were received one year HDM subcutaneous AIT . Fourteen patients were recruited as control group and received only necessary medications. Serum samples were collected at baseline, 6thmoths and 12thof AIT, respectively. Serum samples were tested specific IgE against Der p, Der p 1/2/3 and Der f, Der f 1/2/3, as well as IgG4 against Der p, Der p 1/2 and Der f, Der f 1/2. VAS were collected at the time-points as well. Results:In AIT group, Der p, Der p 1/3, and Der f 1/3 specific IgE levels were significantly higher after one-year treatment, especially for Der p 3. There were 69.2%（18/26） patients whose Der p 3 specific IgE below 0.35 kU/L at baseline but became positive（>0.35 kU/L） after treatment, that is, neosensitization occurred. All tested allergen specific IgG4 level significantly increased after one year AIT treatment and the VAS declined dramatically. However, for patients with neosensitization and without neosensitization, there were no significantly changes concerning to IgG4 level and VAS. Conclusion:Patients undergoing AIT might have a risk of neosensitization to the allergen components in the vaccines. However, the clinical importance of the neosensitization remains unclear and warrants further studies.
目的：由于患者过敏原分子致敏特征和脱敏制剂组成的差异，患者可能在过敏原特异性免疫治疗中产生新的致敏。本研究探讨屋尘螨特异性免疫治疗是否会产生新的致敏，以及新的致敏的临床重要性。 方法：53例尘螨引起的过敏性鼻炎伴随或不伴随哮喘患者接受为期1年的免疫治疗，14例患者作为对照组，按需接受对症药物治疗。分别在治疗前、治疗6个月及12个月采集患者血清，检测屋尘螨、粉尘螨及其组分过敏原（Der p 1/2/3和Der f 1/2/3）特异性IgE抗体及IgG4抗体水平（Der p，Der p 1/2，Der f，Der f 1/2），同时收集3个时间点的VAS评分。 结果：免疫治疗1年后免疫治疗组患者Der p，Der p1/3及Der f 1/3特异性IgE抗体水平显著增高，尤其是Derp 3，其中69.2%（18/26）治疗前该过敏原阴性的患者转为阳性即产生新增过敏。免疫治疗组患者过敏原特异性IgG4抗体浓度1年后显著增高，VAS评分显著下降。对照组特异性IgE及IgG4抗体浓度及VAS评分和治疗前比较，无显著变化。新增致敏的患者和未新增致敏的患者比较，IgG4抗体浓度和VAS评分无显著性差异。 结论：屋尘螨特异性免疫治疗产生了新的致敏，但其临床重要性并不清楚，有待进一步研究。.