Hye-Kyung Park

In July 2025, the Food and Drug Administration (FDA) warned of significant weight loss among young children receiving stimulants for attention‐deficit hyperactivity disorder. However, real‐world evidence on the magnitude and prevalence of stimulant‐associated weight loss remains limited. This study evaluated short‐term weight changes after methylphenidate initiation among youth aged 3–18 years using the Medical record Observation and Assessment of drug safety Common Data Model (MOA CDM) in Korea. We conducted a retrospective study using electronic health record‐based MOA CDM data from January 2008 to December 2024. The cohort included individuals aged 3–18 years with at least one methylphenidate prescription and had available weight measurements. The index date was defined as the first prescription date. Individuals without weight data within 45 days before or 90 days after the index date were excluded. Outcomes included changes in body weight (kg) and weight percentile, and the proportion having a ≥ 10‐percentile decline. Weight percentiles were calculated using the 2017 Korean National Growth Charts for Children and Adolescents. A total of 2087 youths from 17 nationwide hospitals were included; 68.71% were male, and 58.12% were aged 6–10 years. Within 3 months, mean body weight decreased by −0.33 kg (95% confidence interval [CI], −0.44 to −0.22) and mean weight percentile decreased by −2.49 percentiles (95% CI, −2.83 to −2.15). Overall, 21.57% had a ≥ 10 percentile decline, with larger reductions among pre‐school‐aged children (28.57%). Our findings underscores the importance of growth monitoring during treatment initiation.

Profilins are ubiquitous pan-allergens responsible for cross-reactivity between pollens and plant foods. While we previously demonstrated that recombinant Acanthamoeba profilin (rAc-PF) drives allergic airway inflammation via Th2/Th17 pathways in murine models, its clinical relevance in human allergic disease remains unclear. This study investigated rAc-PF as a novel inhalant allergen and its immunological impact on patients with allergic airway diseases. A total of 176 patients with allergic airway diseases underwent skin prick tests with rAc-PF and a standard panel of 55 common aeroallergens. Acanthamoeba-specific and rAc-PF–specific serum IgE levels were quantified using ELISA. To elucidate immune mechanisms, peripheral blood mononuclear cells from atopic asthma patients were stimulated with rAc-PF, and Th2/Th17 cytokine production was analyzed. Thirteen patients (7.4%) showed positive skin prick tests reactions to rAc-PF. This sensitization was significantly associated with tree, grass, and weed pollens, indicating a pan-allergen characteristic due to high cross-reactivity. Notably, one patient sensitized to rAc-PF reacted to no other common inhalants, suggesting rAc-PF as a unique causative agent. Patients exhibited significantly elevated levels of serum Acanthamoeba-specific and rAc-PF–specific IgE compared to healthy controls. Furthermore, rAc-PF stimulation of peripheral blood mononuclear cells from asthmatic patients induced robust production of IL-4, IL-5, IL-13, and IL-17A in humans. rAc-PF is identified as a novel allergen capable of inducing IgE-mediated sensitization and mixed Th2/Th17 responses. The strong association with pollen sensitization supports its role as an environmental pan-allergen. Therefore, rAc-PF should be considered a clinically relevant diagnostic target, especially in patients with polysensitization or unidentified triggers.

Summary Box: Plasma 1‐methylnicotinamide is elevated in dupilumab responders, outperforming conventional type‐2 biomarkers. Combining 1‐methylnicotinamide with FeNO achieves the highest predictive accuracy for dupilumab treatment response.

Background: Hydroxypropyl methylcellulose (HPMC) is a food additive widely used as an excipient in oral pharmaceutical formulations. While widely used in oral formulations, its potential as an ingestible allergen remains largely unrecognized. Case presentation: A 47-year-old man developed urticaria and angioedema after ingesting an HPMC-containing product, including a dietary probiotic drink and a digestive enzyme tablet. He presented with periorbital swelling and generalized urticaria within one hour after consuming a dietary probiotic drink. Two months prior, the patient experienced generalized urticaria and facial swelling after concomitant intake of a vitamin C drink and a digestive enzyme tablet. Skin prick tests revealed positive reactions to the capsule shell of the probiotic drink and digestive enzyme tablet. HPMC was identified as a common excipient in both digestive enzyme tablet and the capsule shell of dietary probiotic drinks and intradermal tests confirmed hypersensitivity to HPMC. An oral provocation test with HPMC induced urticaria, further supporting the diagnosis. Conclusions: This case demonstrates that HPMC can induce immediate hypersensitivity reactions via the oral route. HPMC should be considered a potential culprit in patients with unexplained recurrent allergic reactions to oral medications or dietary supplements, particularly when multiple formulations are involved.

Kim E, et al. Allergy Asthma Immunol Res. 2026 Sep;18(5):652-667. https://doi.org/10.4168/aair.2026.18.5.652

Lee Y, et al. Allergy Asthma Immunol Res. 2025 Nov;17(6):742-753. https://doi.org/10.4168/aair.2025.17.6.742

Shim JS, et al. Allergy Asthma Immunol Res. 2025 Nov;17(6):709-725. https://doi.org/10.4168/aair.2025.17.6.709

Rhyou HI, et al. Allergy Asthma Immunol Res. 2025 Jul;17(4):447-459. https://doi.org/10.4168/aair.2025.17.4.447

Background: Repeated exposure to recombinant profilin from Acanthamoeba (rAc-PF) induces allergic airway responses in vitro and in vivo. Based on the role of toll-like receptors (TLRs) in allergic airway diseases, TLRs play a central role in innate immune responses and the adaptive immune system and regulate responses against antigens through antigen-specific receptors. In this study, we attempted to determine the molecular mechanisms underlying rAc-PF-induced allergic inflammatory responses. Methods: We determined the correlation between rAc-PF and TLRs and analyzed changes in allergic immune responses after blocking multiple TLR signaling under rAc-PF treatment conditions in vitro. We also compared allergic inflammatory responses in TLR2 knockout (KO) and wild-type (WT) mice. To investigate the effect of TLR2 on antigen prototyping and T cell activation in the inflammatory response induced by rAc-PF, we assessed maturation of BMDCs and polarization of naïve T cells by rAc-PF stimulation. Additionally, we compared changes in inflammation-related gene expression by rAc-PF treatment in primary lung epithelial cells isolated from TLR2 KO and WT mice. Results: The rAc-PF treatment was increased the expression level of TLR2 and 9 in vitro. But, there were not significantly differ the others TLRs expression by rAc-PF treated group. And then, the mRNA expression levels of inflammation-related genes were reduced in the TLR2 or TLR9 antagonist-treated groups compared to those in the rAc-PF alone, were no difference the treated with the other TLRs (TLR4, 6, and 7/8) antagonist. The difference was higher in the TLR2 antagonist group. Additionally, the levels of airway inflammatory disease indicators were lower in the TLR2 KO group than in the WT group after rAc-PF treatment. Furthermore, the expression of bone marrow-derived dendritic cell (BMDC) surface molecular markers following rAc-PF stimulation was lower in TLR2 KO mice than in WT mice, and TLR2 KO in BMDCs resulted in a remarkable decline in Th2/17-related cytokine production and Th2/17 subset differentiation. In addition, the expression levels of rAc-PF-induced inflammatory genes were reduced inTLR2 KO primary lung cells compared to those in normal primary lung cells. Conclusion: These results suggest that the rAc-PF-induced airway inflammatory response is regulated by TLR2 signaling.