Fibrosis, gene expression and orbital inflammatory disease

Abstract

Background/aims To clarify the pathogenesis of fibrosis in inflammatory orbital diseases, we analyzed the gene expression in orbital biopsies and compared our results to those reported for idiopathic pulmonary fibrosis. Methods We collected 140 biopsies from 138 patients (58 lacrimal gland; 82 orbital fat). Diagnoses included healthy controls (n=27), nonspecific orbital inflammation (NSOI) (n=61), thyroid eye disease (TED) (n=29), sarcoidosis (n=14), and granulomatosis with polyangiitis (GPA) (n=7). Fibrosis was scored on a zero to three scale by two expert, ophthalmic pathologists. Gene expression was quantified using Affymetrix U133 plus 2.0 microarray. Results Within orbital fat, fibrosis was greatest among subjects with GPA (2.75±0.46) and significantly increased in tissue from subjects with GPA, NSOI, or sarcoidosis (p<0.01), but not for TED, compared to healthy controls (1.13±0.69). For lacrimal gland, the average score among controls (1.36±0.48) did not differ statistically from any of the 4 disease groups. Seventy-three probe sets identified transcripts correlating with fibrosis in orbital fat (false discovery rate < 0.05) after accounting for batch effects, disease type, age and sex. Transcripts with increased expression included fibronectin, lumican, thrombospondin, and collagen types I and VIII, each of which has been reported upregulated in pulmonary fibrosis. Conclusion A pathologist's recognition of fibrosis in orbital tissue correlates well with increased expression of transcripts considered essential in fibrosis. Many of the transcripts implicated in orbital fibrosis have been previously implicated in pulmonary fibrosis. TED differs from other causes of orbital fat inflammation in that fibrosis is not a major component. Marked fibrosis is less common in the lacrimal gland compared to orbital adipose tissue.

Differential transcriptomics in sarcoidosis lung and lymph node granulomas with comparisons to pathogen-specific granulomas

“…Downregulated genes included FABP4, a fatty acidbinding protein associated with activation of proin ammatory macrophages in breast cancer, obesity and leukemia progression (39,40). FABP4, was previously proposed as sarcoidosis candidate gene (22,41). We identi ed that it was also signi cantly downregulated in TB.…”

“…Granulomas are conglomerates of epithelioid and multinucleated giant cells surrounded by CD4+ and CD8+ T lymphocytes that result from the complex immunopathogenesis between host genetic factors, environmental or infectious triggers (11). Sarcoidosis array-based transcriptomic studies in blood, lung and lymph node, lacrimal gland, orbital tissue and skin identi ed tissue-speci c differential gene expression (22)(23)(24)(25), highlighting the importance of assessing different compartments in a multisystemic disease such as sarcoidosis. The majority of these transcriptome studies were focused on identifying gene signatures that differentiate controls from progressive forms of sarcoidosis.…”

Molecular diagnosis: Implications for ophthalmology

“…In addition to classifying orbital tissue on the basis of a histological diagnosis, we have also scored the biopsies on the basis of IgG4 expression (Wong et al, 2014) and fibrosis (Rosenbaum et al, 2015a) and then determined how gene expression correlates with these parameters. IgG4 is the least common of all four isoforms of IgG.…”

“…We scored lacrimal and orbital fat pathology for fibrosis and then correlated gene expression with the fibrosis score. In orbital adipose tissue, fibrosis was associated with gene expression of fibronectin, lumican, thrombospondin, and collagen types I and VIII (Rosenbaum et al, 2015a). These mRNAs have also been implicated in pulmonary fibrosis (DePianto et al, 2014).…”

“…Sixth, surprisingly the “inflammatory signature” detectable in orbital adipose tissue affected by TED is marked by much less inflammation than is characteristic of sarcoidosis, GPA, or NSOI (Rosenbaum et al, 2015e). Seventh, the detection of IgG4+ cells or fibrosis in an orbital biopsy can be correlated with distinct patterns of gene expression (Rosenbaum et al, 2015a; Wong et al, 2014). Eighth, an algorithm based on gene expression shows promise in enhancing diagnostic accuracy from an orbital biopsy (Rosenbaum et al, 2015d).…”