Tehran University of Medical Sciences Journal of Craniomaxillofacial Research 2345-5489 12 4 2026 02 09 270 274 Abdolreza Mohamadnia Chronic Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mohammad Bayat 2. Department of Oral & Maxillofacial Surgery, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran; Craniomaxillofacial Research Center, Tehran University of Medical Sciences, Tehran, Iran. Hossein Dargahi Department of Management Sciences and Health Economic, Health Information Management Research Center, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Shadi Shafaghi Lung Transplantation Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Rosa Karimi Department of Microbiology, School of Biological Sciences, North Tehran Branch, Islamic Azad University, Tehran, Iran. Mahsa Sadat Seid Saleh Department of Biology, Faculty of Sciences, Islamic Azad University, Tehran, Iran. Mohammad Hossein Soltani Department of Biology, Faculty of Sciences, Islamic Azad University, Tehran, Iran. Mona Mohajeri Tehrani Craniomaxillofacial Research Center, Tehran University of Medical Sciences, Tehran, Iran. Farnaz Ahmadi Lung Transplantation Research Center, National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Naghmeh Bahrami Craniomaxillofacial Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran. 2024 10 26 2026 02 01 Introduction: Chronic obstructive pulmonary disease (COPD) is a progressive, irreversible chronic inflammatory disorder characterized by the increased recruitment of monocytes, lymphocytes, and neutrophils. Beyond the lungs, COPD is associated with systemic inflammation, skeletal complications such as osteoporosis, and poor oral and periodontal health, all of which are clinically relevant in oral and maxillofacial practice. This study aims to investigate the changes in miR-155 expression in the peripheral blood of COPD patients compared to healthy individuals.  Materials and Methods: In this descriptive-cross-sectional study, 35 peripheral blood samples from COPD patients and 35 peripheral blood samples from healthy individuals were collected. RNA extraction was immediately performed, followed by Real-Time PCR to assess the changes in miR-155 expression.  Results: The miR-155 biomarker was positive in the peripheral blood of 25 out of 35 patients. In the group of healthy individuals, this biomarker was positive in 6 out of 35 cases. Statistical analysis of the positivity rate of this biomarker between the patient group and the healthy group showed a significant difference. Based on the findings of this study, the expression of miR-155 is increased in COPD patients compared to healthy individuals.  Conclusion: The miR-155 biomarker could potentially play an important role in the identification and diagnosis of COPD in patients. Given the growing evidence that COPD-related systemic and oral inflammation adversely affects periodontal status, jawbone health, and perioperative risk in oral and maxillofacial surgery, circulating miR-155 may also serve as a useful adjunct biomarker for risk stratification and multidisciplinary management of COPD patients in craniomaxillofacial settings. However, further studies are recommended.  Keywords: COPD; miRNA; Real-Time PCR; miR-155. https://jcr.tums.ac.ir/index.php/jcr/article/view/520 https://jcr.tums.ac.ir/index.php/jcr/article/download/520/471