2598. Macrophage Migration Inhibitory Factor May Contribute to Disseminated Coccidioidomycosis Susceptibility

Abstract

Background

Disseminated coccidioidomycosis occurs in <1% of cases, and genetic polymorphisms may account for some of the variability in infection severity. Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine with two promoter polymorphisms linked to variability in expression. High expression MIF polymorphisms have been associated with granulomatosis with polyangitis (GPA), sarcoidosis and tuberculosis. Despite the overlap between MIF and Coccidioides immunity, MIF has never been studied in coccidioidomycosis.

Methods

A549 cells transfected with MIF promoter/luciferase plasmids of 0 or 8 CATT repeats were stimulated with 50 µg/mL of inactivated C. posadasii spherule lysate, and luciferase expression was measured as relative units (RU) of luminescence. Genomic DNA from patients with disseminated coccidioidomycosis (n = 37) and healthy controls (n = 371) was analyzed for the 794 CATT_5-8 microsatellite and the -173 G/C SNP. Cohorts were divided into self-identified African Americans and Caucasians, and allele frequencies were compared using Fisher exact test. Plasma MIF levels were analyzed by enzyme-linked immunosorbant assay using specific antibodies, and levels were compared by T-test.

Results

Human lung epithelial cells exposed to Coccidioides spherules had significantly higher MIF expression than unexposed cells (3.94 ± 0.44 vs. 3.02 ± 0.24 RU, P = 0.0162). Among Caucasians (n = 26), the high MIF expression −173C containing genotype was present in 50% of the coccidioidomycosis patients vs. 40% of healthy controls (P = 0.396). The -794 CATT₇ containing genotype was present in 40% of patients vs. 27% of controls (p = 0.240). Plasma MIF levels were higher in coccidoidomycosis patients with high- vs. low-expression alleles (P = 0.008), but lower in patients vs. controls (P < 0.0001).

Conclusion

Coccoidioides spherules stimulated MIF expression in human lung epithelial cells supporting the hypothesis that MIF is involved in immunity against this pathogen. In Caucasian subjects, the higher MIF expression genotypes were more common in patients with disseminated coccidioidomycosis when compared with healthy controls, although significance was limited by sample size. This is consistent with high expression MIF alleles associated with other granulomatous diseases, and may reflect destruction of the granuloma with pathogen dissemination.

Disclosures

All authors: No reported disclosures.