Expression of HOXB7 in the lung of patients with idiopathic pulmonary fibrosis: a proof-of-concept study and clinical significance

<bold>Background:</bold> Molecular pathways involved in the pathogenesis of IPF still need to be fully clarified.HOXB7,a member of homeobox (HOX) gene family, has been involved in cell proliferation, motility and angiogenesis of several cancers. The aim of this study is to investigate the expression of HOXB7 in lung biopsies of IPF patients. <bold>Methods:</bold> Immunohistochemical (IHC) analysis was run on lung tissue samples from surgical lung biopsy (SLB) of 19 patients with IPF selected from the IPF database of the University Hospital of Modena.HOXB7 expression was quantified as average pixel intensity of the staining area and compared with that of 5 control patients with no histological evidence of lung fibrosis. Correlation between HOXB7 expression and clinical, functional, radiological status at the time of the SLB and localization of HOXB7 expression in lung niche were assessed. <bold>Results:</bold> IHC quantification showed that HOXB7 signal intensity was higher in IPF patients compared to controls (difference between means = 15.90±6.0, p=0.0157).HOXB7 expression resulted higher in IPF patients with a higher radiological extent of fibrosis (50-75%) compared to those with lower extent (0-25%) (difference between means = 25.74 ± 6.72, p=0.004).IHC investigation on serial slides of IPF patients showed a specific co-localization of HOXB7 with markers of alveolar epithelial type II and type I cells, mesenchymal stromal cells and fibroblasts within the lung niche. <bold>Conclusions:</bold> The expression of HOXB7 is higher in lungs of IPF patients compared to controls, being represented in different cellular compartments within the lung niche. Further investigations are needed to clarify its role in IPF pathogenesis.