Fig. 4: Deep penetration of fibrotic lung tissue by PRS-220 upon inhalation translates into superior attenuation of fibrosis in vivo.

a Fibrotic remodeling of the lung assessed 41 days after silica challenge in comparison to saline challenge of mouse lungs by Hematoxylin and Eosin staining. b PK profile of PRS-220 in lung tissue and plasma delivered via nose-only inhalation at 3 dose levels (0.2, 1 and 5 mg/kg targeted delivered dose) to healthy or silica challenged mice. Graph shows data of n = 4 animals per group and timepoint as mean ± SD. c Immunofluorescence imaging of PRS-220 (magenta) 2 h after inhaled delivery to fibrotic, silica-challenged mouse lungs (day 41, targeted delivered dose 5 mg/kg). Cell nuclei are stained with DAPI (blue). d Co-immunofluorescence staining of PRS-220 (magenta), club cell marker CC10 (green) and e smooth muscle cell & myofibroblast marker aSMA (green) in lung tissues from c. f Localization of PRS-220 (magenta) in relation to cells expressing its target assessed by co-immunofluorescence imaging of PRS-220 and CCN2 (green) in lung tissues from c. g Scheme of the in vivo efficacy study in mice. Created in BioRender. Pavlidou, M. (2025) https://BioRender.com/x52k357h Total collagen deposition in the lung by measuring lung hydroxyproline. Individual data points of n = 3 (saline) and n = 6 (all other) animals per treatment group including mean ± SD are shown (One-way ANOVA with Šídák’s multiple comparisons test; *p ≤ 0.05, **p ≤ 0.01, ns (not statically significant) p > 0.05). i Lung tissue mRNA gene expression of Timp1 and j Ccl2 with Rn18s serving as reference gene. Individual data points of n = 3 (saline) and n = 6 (all other) animals per treatment group including mean ± SD are shown (One-way ANOVA with Šídák’s multiple comparisons test; *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ns (not statically significant) p > 0.05). For all imaging analyses, representative images of in total n = 4 mice per treatment group are shown. Source data are provided as a Source Data file.