New Insights via RNA Profiling of Formalin-Fixed Paraffin-Embedded Lung Tissue of Pulmonary Fibrosis Patients

In sporadic idiopathic pulmonary fibrosis (sIPF) and pulmonary fibrosis caused by a mutation in telomere (TRG-PF) or surfactant related genes (SRG-PF), there are a number of aberrant cellular processes known that can lead to fibrogenesis. We investigated whether RNA expression of genes involved in these processes differed between sIPF, TRG-PF, and SRG-PF and whether expression levels were associated with survival. RNA expression of 28 genes was measured in lung biopsies of 26 sIPF, 17 TRG-PF, and 6 SRG-PF patients. Significant differences in RNA expression of TGFBR2 ( p = 0.02) and SFTPA2 ( p = 0.02) were found between sIPF, TRG-PF, and SRG-PF. Patients with low (<median) expression of HSPA5 ( p = 0.04), COL1A1 ( p = 0.03), and ATF4 (0.005) had significantly longer survival rates than patients with high (≥median) expression of these genes. In addition, we scored for low (0) or high (1) expression of six endoplasmic reticulum (ER) stress genes ( HSP90B1, DDIT3, EDEM1, HSPA5, ATF4, and XBP1) and found that patients with high expression in a low number of ER stress genes (total score 0-1) had longer survival rates than patients with high expression in a high number of ER stress genes (total score 2-6) ( p = 0.03). In conclusion, there are minor differences between sIPF, TRG-PF, and SRG-PF and high expression in a high number of ER stress genes significantly associated with shorter survival time, suggesting that ER stress may be a target for therapy for PF.