Third, although we have previously reported that elevation of HO-1 induced lethal fibrosis in acute exacerbation of IPF triggered by COVID-19, it is necessary to perform a molecular pathological study regarding the in vivo dynamics of serum HO-1 elevation and pro-fibrotic cytokines such as tissue growth factor-β143. The gene discussed is HMOX1; the disease is idiopathic pulmonary fibrosis.