It is well-established that PQ poisoning can cause acute oxidative stress and severe lung injury during the exposure, finally leading to irreversible pulmonary fibrosis.29 To the best of our knowledge, this is the first investigation that focused on relevance of S100A8, S100A9 to PQ-induced pulmonary fibrosis in humans and rat. Here, S100A9 is linked to pulmonary fibrosis.