Haemophilus abundance is associated with response to sublingual immunotherapy in children with allergic rhinitis

The nasal microbiome's role in predicting sublingual immunotherapy (SLIT) efficacy in children with allergic rhinitis (AR) remains unclear. Haemophilus, a Proteobacteria genus linked to respiratory inflammation, is a promising candidate biomarker.

To evaluate Haemophilus dynamics as a potential predictor of SLIT response in children with moderate-severe AR.

In this prospective cohort, 63 children with AR and 40 healthy controls (CG) were enrolled. AR patients were stratified by disease severity (mild [MAR] vs. moderate-severe [MSAR]), with MSAR patients receiving 1-year standardized house dust mite SLIT. Based on >20% reduction in Total Nasal Symptom Score (TNSS), patients were classified as responders (RG, n = 25) or non-responders (NRG, n = 15). Nasal microbiome was profiled via 16S rDNA sequencing.

Compared to CG, AR children showed increased alpha diversity (Chao1, p < .05; Shannon, p < .01) and enrichment of Staphylococcus. MSAR patients had significantly higher Proteobacteria abundance, particularly Haemophilus, compared to MAR (LDA score >4, p < .001). After SLIT, RG patients showed normalized microbial evenness (Pielou E index) to CG levels, driven by marked Haemophilus depletion (p < .001). In contrast, NRG patients maintained high Haemophilus abundance. Haemophilus and Moraxella showed strong positive correlation (r = .68, p < .001), with both decreasing in RG post-SLIT.

Elevated nasal Haemophilus is associated with AR severity, and its depletion correlates with SLIT efficacy. Haemophilus may serve as a clinically actionable microbial biomarker for monitoring SLIT response in pediatric AR, offering a novel precision medicine approach to allergen immunotherapy.