Objective: The long-term efficacy of single-allergen-specific immunotherapy in polysensitized allergic rhinitis (AR) subjects remains uncertain. This study aimed to evaluate the long-term efficacy and safety of dust mite subcutaneous immunotherapy (SLIT) in monosensitized and polysensitized children with AR. Methods: This prospective study recruited 130 children with AR, divided into a monosensitization group and a polysensitization group. Patients received standardized dust mite SLIT for 3 years and were followed up for 5 years. Total nasal symptom score (TNSS), symptom and medication score (SMS), visual analogue scale (VAS) and rhinoconjunctivitis quality of life questionnaire (RQLQ) were assessed and compared between the two groups at T0 (before treatment), T1 (1 year of SLIT), T2 (2 years of SLIT), T3 (end of SLIT) and T5 (2 years after the end of SCIT). Safety was assessed through adverse events (AEs). Results: 51 monosensitized and 50 polysensitized children completed this study. At the end of SCIT, 47 monosensitized and 46 polysensitized children were effectively treated, respectively, with no significant difference (P > 0.05). TNSS, SMS, VAS and RQLQ were significantly lower in T1, T2, T3 and T5 in the two groups compared with T0 (P < 0.05). The differences in TNSS, SMS, VAS and RQLQ between the two groups were not statistically significant at T1, T2, T3 and T4 (P > 0.05), while the differences were significant at T5 (P < 0.05). No serious AEs were reported. Conclusion: Standardized dust mite SCIT has similarly beneficial long-term efficacy and safety in monosensitized and polysensitized children. Monosensitization children appear to receive more durable benefits.

Group 2 innate lymphoid cells (ILC2) play a critical role in type 2 immunity. Although their classical activators are known to be host epithelial-derived alarmin cytokines released from tissue damage at barrier sites during microbial infections and allergen exposures, it remains elusive whether ILC2 cells can be directly activated by microbial ligands. Here we examined a number of microbial ligands and identified lipopolysaccharides (LPS) from multiple species of Gram-negative bacteria potently stimulated the cultured human ILC2 to proliferate and produce massive amounts of type 2 effector cytokines IL-5 and IL-13. RNA-seq data revealed a remarkably similar set of type 2 immune responsive genes induced by LPS and IL-33. However, blocking IL-33 receptor signaling failed to decrease the effects of LPS. In contrast, blocking TLR4 receptor, NF-kB and JAK pathways completely abolished the growth and function of LPS-treated human ILC2. Furthermore, ILC2 cells of TLR4 deficient mice were unable to respond to LPS treatment in vitro and in vivo. Importantly, patients with allergic rhinitis, atopic dermatitis and bacteremia had an increased number of peripheral blood ILC2 cells that correlated with elevated serum endotoxin. Collectively, these findings support a non-canonical mode of direct activation of human ILC2 cells via the LPS-TLR4-NF-kB/JAK signaling axis, which is independent of the classical IL-33-ST2 pathway. Thus, targeting TLR4 signaling pathway might be developed as an alternative approach to treat microbial infection-associated and ILC2-mediated inflammatory conditions.