A preliminary investigation of the differences in immune responses in different strains of mice with localized allergic rhinitis tolerance models

Abstract

Objectives

This study aimed to compare systematically strain-specific immune differences between BALB/c and C57BL/6 mice in a local tolerance model and explore the underlying mechanisms.

Methods

BALB/c and C57BL/6 mice received daily intranasal ovalbumin (OVA; 25 mg/ml, 10μl/nostril) or PBS for 15 weeks. Systemic responses (serum OVA-specific IgE, IgG1, IgG2a; splenocyte cytokine secretion: IL-4, IL-10, IFN-γ) and local nasal responses (symptoms, histopathology: polymorphonuclear/goblet cell infiltration; immunohistochemistry: TGF-β, IL-10, eotaxin; RNA-seq transcriptomics of nasal mucosa) were assessed at the 8th and 15th weeks.

Results

BALB/c mice initially exhibited worsening nasal symptoms, which was followed by significant alleviation. In contrast, C57BL/6 mice showed a significant worsening of symptoms. Serum levels of IgE, IgG1, and IgG2a increased significantly over time in BALB/c mice. In C57BL/6 mice, serum IgE and IgG1 levels also increased significantly, while IgG2a levels showed no significant changes. In splenocyte supernatants, BALB/c mice showed IL-4 levels that initially increased significantly but later decreased significantly, whereas IL-10 levels were significantly elevated and sustained. Conversely, C57BL/6 mice exhibited no significant changes in these splenocyte cytokines. Within nasal mucosa, BALB/c mice displayed polymorphonuclear cell infiltration and significantly elevated eotaxin levels, which subsequently stabilized, alongside significant upregulation of TGF-β and IL-10 expression. At 15th week, C57BL/6 mice demonstrated significantly higher nasal PMN infiltration and eotaxin levels compared to BALB/c mice, but showed no significant increase in TGF-β or IL-10 compared to controls. RNA-seq analysis of nasal mucosa revealed that BALB/c mice at 15th week exhibited significant upregulation of genes involved in biological processes, tolerance-related signaling pathways, and negative regulatory pathways. Conversely, C57BL/6 mice showed significant upregulation of genes associated with cell synthesis- and secretion-related pathways.

Conclusion

Based on the criteria defining “local tolerance” in this model—significant symptom attenuation despite allergen escalation coupled with downregulation of nasal inflammatory markers (eotaxin, polymorphonuclear cell infiltration)—local tolerance was successfully induced in BALB/c mice by long-term OVA stimulation, but not in C57BL/6 mice. The normal function of T regulatory cells is key to establishing local tolerance.