Association of polymorphisms in the collagen region of SP-A2 with increased levels of total IgE antibodies and eosinophilia in patients with allergic bronchopulmonary aspergillosis

Abstract

Background: Studies from our group have shown a protective role of pulmonary surfactant protein A (SP-A) against lung allergy and infections caused by Aspergillus fumigatus.

Objective: Present study investigated the association of polymorphisms in the collagen region of SP-A1 and SP-A2 (genes encoding SP-A) with allergic bronchopulmonary aspergillosis (ABPA) and its clinical markers.

Methods: Genomic DNA was extracted from blood samples of patients with ABPA and age-matched, unrelated control subjects. The polymorphisms were detected by means of PCR amplification and sequencing of the collagen region of SP-A1 and SP-A2.

Results: Two exonic (SP-A2 G1649C and SP-A2 A1660G, 10 patients and 11 control subjects) and 2 intronic (SP-A2 T1492C, 8 patients and 8 control subjects; SP-A1 C1416T, 5 patients and 7 control subjects) polymorphisms in the collagen region of SP-A2 and SP-A1 showed significant association with patients with ABPA. A significantly higher frequency of the AGA allele (A1660G) of SP-A2 was observed in patients with ABPA in comparison with control subjects (P =.0156, odds ratio [OR] = 4.78, 95% CI = 1.23 < OR < 18.52). This polymorphism, when existing along with a nonredundant polymorphism, SP-A2 G1649C (Ala91Pro) resulted in a stronger association with ABPA (A1660G and G1649C: P =.0079, OR = 10.4, 95% CI = 1.62 < OR < 66.90). Patients with ABPA with GCT and AGG alleles showed significantly high levels of total IgE and percentage eosinophilia versus patients with ABPA with CCT and AGA alleles.

Conclusion: The results indicated that SP-A2 G1649C and SP-A2 A1660G, polymorphisms in the collagen region of SP-A2, might be one of the contributing factors to genetic predisposition and severity of clinical markers of ABPA.