We, the authors, Editors and Publisher of Immunopharmacology and Immunotoxicology, have retracted the following article: Gang Wang, Jian Zhu & LiPeng Liu. Curcumin deactivates M2 macrophages to alleviate lung fibrosis in IgG4-related disease through activating the toll-like receptor 9 pathway. Published online: 15 Nov 2021. https://doi.org/10.1080/08923973.2021.2001498Since publication, the authors noted there are serious concerns with the reliability of the published results. The positive results in Figure 1 in the article could not be reproduced when the test was repeated. This means that curcumin has not been proven to treat pulmonary fibrosis caused by IgG4-related diseases.The authors alerted the Editor and Publisher to the problems, and all have agreed to retract the article to ensure the integrity of the scholarly record. The authors apologise for this error.We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted'.