The study of a possible correlation between serum levels of interleukin 17 and clinical severity in patients with allergic rhinitis

Role of IL-17 in atopy-A systematic review

PURPOSE OF REVIEW

Atopy is defined as the genetic predisposition to react with type I allergic diseases such as food-, skin-, and respiratory allergies. Distinct molecular mechanisms have been described, including the known Th2 driven immune response. IL-17A (IL-17) is mainly produced by Th17 cells and belongs to the IL-17 family of cytokines, IL-17A to F. While IL-17 plays a major role in inflammatory and autoimmune disorders, more data was published in recent years elucidating the role of IL-17 in allergic diseases. The present study aimed to elaborate specifically the role of IL-17 in atopy.

METHODS

A systematic literature search was conducted in MEDLINE, Embase, and Cochrane Central Register of Controlled Trials, regarding IL-17 and atopy/allergic diseases.

RESULTS

In total, 31 novel publications could be identified (food allergy n = 3, allergic asthma n = 7, allergic rhinitis [AR] n = 10, atopic dermatitis [AD] n = 11). In all allergic diseases, the IL-17 pathway has been investigated. Serum IL-17 was elevated in all allergic diseases. In AR, serum and nasal IL-17 levels correlated with the severity of the disease. In food allergies, serum IL-17E was also elevated in children. In AD, there is a trend for higher IL-17 values in the serum and skin specimen, while it is more expressed in acute lesions. In allergic asthma, serum IL-17 levels were increased. In two studies, higher serum IL-17 levels were found in severe persistent asthmatic patients than in intermittent asthmatics or healthy controls. Only one therapeutic clinical study exists on allergic diseases (asthma patients) using a monoclonal antibody against the IL-17 receptor A. No clinical efficacy was found in the total study population, except for a subgroup of patients with (post-bronchodilator) high reversibility.

SUMMARY

The role of IL 17 in the pathogenesis of allergic diseases is evident, but the involvement of the Th17 cytokine in the pathophysiological pathway is not conclusively defined. IL-17 is most likely relevant and will be a clinical target in subgroups of patients. The current data indicates that IL-17 is elevated more often in acute and severe forms of allergic diseases.

Association of interleukin-12B rs6887695 with susceptibility to allergic rhinitis

Interleukin-12 (IL-12) is a heterodimeric cytokine encoded by two separate genes, IL12A and IL12B, which may play a regulatory role in allergen-induced inflammation through CD4⁺ T-cell subsets polarization. The aim of this study was to investigate the association of single-nucleotide polymorphisms (SNPs) in the IL12B gene with susceptibility to allergic rhinitis (AR). We performed a case-control study including 130 AR patients and 130 healthy controls to evaluate the possible association between IL12B gene SNPs (rs3212227, rs6887695) and the risk of AR using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our results showed no significant association between IL12B rs3212227 A > C polymorphism with AR. In contrast, the GC genotype of rs6887695 G > C was associated with susceptibility to AR in comparison with the GG genotype (p = 0.049, OR = 1.684, 95% CI: 1.002-2.83). We also observed a statistically significant difference in the additive model (GC versus GG + CC, p = 0.03, OR = 1.705, 95% CI: 1.040-2.794) for SNPs rs6887695. Furthermore, haplotypes analysis demonstrated that C-C haplotype was associated with an increased risk of AR (p = 0.01, OR = 1.845, 95% CI: 1.114-3.057). Our findings suggest that IL12B rs6887695 polymorphism may be a potential biomarker for susceptibility to AR in an Iranian population.

Lipid Profile and IL-17A in Allergic Rhinitis: Correlation With Disease Severity and Quality of Life

BACKGROUND

Recent data display the possible role of cytokines such as interleukin-10 (IL-10), IL-17 and IL-23 as a link between dyslipidemia and atopy; however, the relationship between dyslipidemia, allergic rhinitis (AR), and the underlying mechanisms involved is unclear.

PURPOSE

To measure the lipid profile and IL-17A level in AR patients in comparison to healthy controls, and correlate serum lipid level with the severity of symptoms and quality of life (QoL) of AR patients.

PATIENTS AND METHODS

Peripheral blood samples were collected from AR patients (n=70) and a control group (n=80). Samples were analyzed for serum total IgE by ELISA, serum lipid profile, and IL-17A level by ELISA. Severity of AR symptoms was assessed by visual analogue scale (VAS) score and the rhinoconjunctivitis QoL questionnaire.

RESULTS

Serum lipid profile and level of IL-17A in AR patients were significantly higher in comparison to controls (P < 0.001). Positive correlations were found between total cholesterol (TC) and the severity of AR and QoL. IL-17A was positively correlated with triglyceride (TG) level and low-density lipoprotein cholesterol (LDL-C) (P=0.011, r=0.303; P=0.043, r=0.242, respectively). Additionally, IL-17A was negatively correlated with high-density lipoprotein cholesterol (HDL-C) level (P=0.036, r=-0.251). IL-17A was positively correlated with both age and VAS score with statistical significance (P=0.033, r=0.225; P=0.011, r=0.302, respectively).

CONCLUSION

Dyslipidemia might play a potential role in the severity of AR symptoms and impairment of patients' QoL. Highlighting this association might alert physicians to evaluate the lipid profile in AR patients for timely diagnosis and treatment of dyslipidemia in an attempt to improve disease control and improve QoL.