[Effect of interleukin-17 gene polymorphism on susceptibility to cow's milk protein allergy in infants and its association with gut microbiota].

Objectives: To investigate the effect of interleukin-17 (IL-17) gene polymorphism on the susceptibility to cow's milk protein allergy (CMPA) in infants and its association with gut microbiota.

Methods: A prospective study was conducted involving 100 infants diagnosed with CMPA at the Women and Children's Hospital of Ningbo University from January 2022 to October 2024. A total of 100 healthy infants undergoing routine check-ups at the same hospital during the same period was enrolled as the control group. Medical information was obtained through the electronic medical record system. IL-17A (rs2275913) and IL-17F (rs1889570) polymorphisms were detected using polymerase chain reaction-restriction fragment length polymorphism method. Serum IL-17 levels were measured using enzyme-linked immunosorbent assay, and high-throughput sequencing was employed to analyze the relative abundance of Lactobacillus and Bifidobacterium. Multivariate logistic regression analysis was used to explore the influencing factors of CMPA occurrence in infants.

Results: The proportions of infants with a family history of allergy and those with vitamin D deficiency or insufficiency were significantly higher in the CMPA group compared to those in the control group (P<0.05). The distribution of IL-17F (rs1889570) genotypes showed significant differences between the CMPA and control groups (P<0.05), with the frequency of the A allele being significantly higher in the CMPA group (P<0.05). Multivariate logistic regression analysis revealed that a family history of allergy, vitamin D deficiency or insufficiency, and carrying the IL-17F (rs1889570) AA genotype were independent influencing factors for CMPA in infants (P<0.05). Infants in the CMPA group with the IL-17F (rs1889570) AA genotype had significantly higher serum IL-17 levels compared to those with AG/GG genotypes (P<0.05), while the relative abundance of Lactobacillus and Bifidobacterium was significantly lower (P<0.05).

Conclusions: IL-17F (rs1889570) gene polymorphism influences susceptibility to CMPA in infants, potentially through mechanisms involving IL-17 expression and the relative abundance of gut probiotics.