Prominent renal expression of a murine leukemia retrovirus in experimental systemic lupus erythematosus

A role for retroviruses in human systemic lupus erythematosus (SLE) and in mouse lupus models such as the New Zealand Black and White mice (NZB/W) strain has been postulated. This study compared the gene profile of nephritic NZB/W kidney with nondiseased NZW controls. The most highly upregulated gene (5.5-fold) hybridized with an expressed sequence tag on a cDNA microarray, which was sequenced and found to correspond with an endogenous murine retrovirus related to the Duplan strain (EDV, L08395). NZB/W kidney contained the full-length 4.2-kb EDV transcript. By 4 wk of age in NZB/W mice, an age preceding renal histologic disease, the EDV transcript was more than threefold increased relative to NZB or NZW control strains. This upregulated expression tended to fall with progression of renal histologic disease. By in situ hybridization, the EDV transcript was highly expressed in tubules of NZB/W mice. There was also upregulated expression of EDV transcript in NZB/W lung and brain, sites of inflammation in this strain, but not in spleen or liver. Thus, using microarrays, the most highly expressed gene in mouse lupus nephritis corresponded to an endogenous retrovirus. This retroviral transcript was highly expressed in the kidneys of lupus mice and tended to decline with advancement of disease. The remarkable upregulation of the EDV transcript only in the setting of active disease suggests this transcript is involved in inflammatory disease.