Identification of Microbial DNA in Chorioretinal Lesions Associated With Chronic Granulomatous Disease

Abstract

Purpose: : Chronic granulomatous disease (CGD) is characterized by granulomatous inflammation of multiple systemic organs secondary to a defect in the ability to generate reactive oxidative species. The most common and severe form of CGD is an X-linked recessive defect in the gene encoding the gp91^phox subunit of NAPDH oxidase, which is involved in microbial killing. This predisposes individuals to severe, recurrent infections and granulomatous inflammation. Ocular manifestations include infectious and non-infectious keratitis, and chorioretinal lesions. We sought to identify whether the ocular pathology associated with CGD is caused by the same pathogens via the known mechanisms of the systemic manifestations of this disease.

Methods: : Six CGD cases with ocular autopsies were collected. Cells from the chorioretinal scars and normal chorioretinal tissue were microdissected and prepared for detection of the pathogens implicated in the active infections. Both sense and antisense primers for Pseudomonas aeruginosa, Actinobacter baumannii, Staphylococcus epidermidis, Mycobacterium avium, Aspergillus flavus, Aspergillus funigatus, Aspergillus terreus and Candida glabrata were used for PCR amplification. DNA was prepared with ³²P and AmpliTaq buffer from Applied Biosystems. Amplifications were carried out.

Results: : Of the autopsy cases of CGD-associated deaths at the NIH from 2000 to 2008, six had documented systemic manifestations from the above mentioned organisms. Of these six, three demonstrated chorioretinal scars associated with CGD. P. aeruginosa and S. epidermidis DNA was identified in two chorioretinal scars of two different cases, whereas no evidence of other tested microbial DNA was found. No microbial DNA was detected in normal ocular tissue of the same eye samples.

Conclusions: : This is the first direct evidence of microbial DNA presence in chorioretinal lesions in the eyes of two patients with CGD, in whom isolation was specific to diseased tissue. The presence of P. aeruginosa and S. epidermidis DNA suggests a potential mechanism by which these lesions may occur. It is possible that the ocular lesions in CGD may occur as sequelae of the infectious process caused by the underlying defect in CGD. While aggressive anti-microbial therapy is recommended, further studies are needed to delineate the precise mechanisms by which CGD-associated chorioretinal lesions form.

Keywords: pathology: human • bacterial disease • chorioretinitis