Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 22 4 2023 09 03 366 378 Mohadeseh Valizadeh Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran Shiva Irani Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran Mahmood Tavallaei Genetics Research Center, Baqiatallah Medical Sciences University, Tehran, Iran Masoud Soleimani Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Department of Cell Therapy and Hematology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran 2023 07 03 2023 08 07 Sulfur mustard (SM) or mustard gas is a blister chemical agent that causes pulmonary damage by triggering inflammation and oxidative injury. Alterations in microRNA (miR) transcript levels are found in pulmonary diseases and even inflammation. Therefore, we evaluated the expression levels of miR-20a-5p, miR-21-5p, and two target transcripts (transforming growth factor-beta [TGF-β1] and TGF-β receptor 2 [TGFR2]) in lung, serum, and skin samples from patients exposed to SM. Total RNA was extracted from lung, serum, and skin samples of patients with moderate (n=10) and high (n=10) SM exposure, as well as 10 healthy subjects. Following the synthesis of complementary deoxyribonucleic acid using real-time polymerase chain reaction, we determined the expression levels of miR-20a-5p, miR-21-5p, TGF-β1, and TGFR2 transcripts. Furthermore, we evaluated the sensitivity and specificity of the chosen miRs by employing receiver operating characteristic (ROC) curves and calculating the area under the ROC curve. The results showed that miR-20a-5p and miR-21-5p expressions in the groups with moderate and high SM exposure were significantly lower than the normal controls. The expression analysis demonstrated that TGFR2 was significantly less expressed in skin samples exposed to SM in both groups of patients compared with healthy controls. Furthermore, the TGF-β1 expression in the skin samples of the group with moderate SM exposure was lower than that of the normal control group. Our findings suggest that miR-20a-5p, miR-21-5p, TGF-β1, and TGFR2 expressions could be used as potential biomarkers for discriminating SM-exposed patients from healthy individuals. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3873 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3873/1974