# Antibodies against Human Cytomegalovirus in the Pathogenesis of Systemic Sclerosis: A Gene Array Approach

## TL;DR

This study explores how antibodies against a human cytomegalovirus protein may contribute to the development of systemic sclerosis by affecting endothelial cells and fibroblasts.

## Contribution

The study demonstrates a novel link between anti-cytomegalovirus antibodies and fibroblast activation in systemic sclerosis.

## Key findings

- Anti-UL94 antibodies induce endothelial cell apoptosis and upregulate genes related to adhesion, chemokines, and apoptosis.
- Dermal fibroblasts exposed to anti-UL94 antibodies show a 'scleroderma-like' phenotype with increased extracellular matrix and cytokine gene expression.
- Results were confirmed using real-time PCR, ELISA, and Western blotting.

## Abstract

Systemic sclerosis is an autoimmune disease characterized by immunological abnormalities, vascular damage, and fibroblast proliferation. We have previously shown that a molecular mimicry mechanism links antibodies against the human-cytomegalovirus-derived protein UL94 to the pathogenesis of systemic sclerosis. The UL94 epitope shows homology with NAG-2, a surface molecule highly expressed on endothelial cells. Anti-UL94 peptide antibodies purified from patients' sera induce apoptosis of endothelial cells upon engagement of the NAG-2–integrin complex.

We show here that NAG-2 is expressed on dermal fibroblasts and that anti-UL94 antibodies bind to fibroblasts. We have used the gene array strategy (Affimetrix oligonucleotide microarrays) to analyze the transcriptional profile in response to a 4-h and an 8-h treatment with antibodies against the UL94 peptide in endothelial cells and dermal fibroblasts. Exposure of endothelial cells to anti-UL94 antibodies had a profound impact on gene expression, resulting in the upregulation of 1,645 transcripts. Several gene clusters were upregulated including genes encoding adhesion molecules, chemokines, colony-stimulating factors (CSFs), growth factors, and molecules involved in apoptosis. Following antibody stimulation, dermal fibroblasts showed an upregulation of 989 transcripts and acquired a “scleroderma-like” phenotype. Indeed, genes involved in extracellular matrix deposition, growth factors, chemokines, and cytokines were upregulated. We confirmed the microarray results by real-time quantitative polymerase chain reaction and by measuring some of the corresponding proteins with ELISA and Western blotting.

Our results show that anti-human-cytomegalovirus antibodies may be linked to the pathogenesis of systemic sclerosis not only by inducing endothelial cell activation and apoptosis but also by causing activation of fibroblasts, one of the hallmarks of the disease.

Anti-human-cytomegalovirus antibodies may be linked to the pathogenesis of systemic sclerosis by inducing endothelial cell activation and apoptosis, and fibroblast activation and proliferation.