Biomarkers of exposure and progression in patients with hypersensitivity pneumonitis and exposed workers (EXIMIOUS project)

<bold>Introduction:</bold> Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) affecting genetically predisposed individuals following recurrent inhalation of environmental antigens. The aim of the study is to evaluate YKL-40 and KL-6 as markers of exposure and progression in patients with HP caused by the inhalation of bird or fungal antigens. <bold>Materials and methods:</bold> Patients were classified into progressive (n=18) and non-progressive HP (n=73) using ATS 2022 criteria in relation to patients with ILD. A population of park workers (n=74) was used as control group. Serum levels of KL6 and YKL-40 were determined as well as IgG antibodies specific to: pigeon, parrot, <italic>Aspergillus sp.</italic> and <italic>Penicillium sp.</italic> <bold>Results:</bold> Serum KL6 levels were higher in the progressive HP group than in the non-progressive HP and control groups (p=0.0401 and p<0.0001, respectively). In patients with non-progressive HP, KL6 was also increased than the control group (p<0.0001). Serum YKL-40 levels were higher in HP patients with and without progression than in the control group (p<0.0001). Significant higher levels of specific IgGs to Penicillium sp and parrot were observed in both HP patient groups (progressive and non-progressive) than in the control group (p=0.0010 and 0.0017 for Penicilium sp and p=0.0347 and p<0.0001 for parrot). <bold>Conclusion:</bold> KL-6 and YKL-40 can be used as a biomarkers of diagnosis in patients with HP besides KL-6 can be used as a biomarker of progression. In all groups a high exposure to pigeon, parrot, <italic>Aspergillus sp.</italic> and <italic>Penicilium sp.</italic> was observed. <bold>Funded by:</bold> European Union's Horizon 2020 research and innovation programme under grant agreement No 874707.