Osteomyelitis and immune cell phenotypes: a study based on a Mendelian randomisation approach

Abstract Background: Osteomyelitis is a severe bone marrow infection, whose pathogenesis is not fully understood. This study aims to explore the causal relationship between immune cell characteristics and osteomyelitis, in hopes of providing new insights for the prevention and treatment of osteomyelitis. Methods: Based on two independent samples, this study employed a two-sample Mendelian randomization (MR) analysis to assess the causal relationship between 731 immune cell characteristics (divided into 7 groups) and osteomyelitis. Genetic variants were used as proxies for risk factors to ensure the selected instrumental variables meet the three key assumptions of MR analysis. GWAS data for immune characteristics came from the public GWAS catalog, while data for osteomyelitis was sourced from the Finnish database. Results: At a significance level of 0.05, 21 immune phenotypes were identified as having a causal relationship with the development of osteomyelitis. In the B cell group, phenotypes such as Memory B cell %B cell, CD20- %B cell, and Memory B cell %lymphocyte showed a positive causal relationship with osteomyelitis, while Naive-mature B cell %B cell and IgD- CD38- AC phenotypes showed a negative causal relationship. In addition, specific immune phenotypes in the cDC cell group, Myeloid cell group, TBNK cell group, T cell maturation stage, and Treg cell group also showed significant associations with osteomyelitis. Through reverse MR analysis, it was found that osteomyelitis had no significant causal impact on these immune phenotypes, suggesting that the occurrence of osteomyelitis might not in turn affect these immune cell phenotypes. Conclusion: This study reveals for the first time the causal relationship between specific immune cell characteristics and the development of osteomyelitis, providing a new perspective for understanding the immune mechanism of osteomyelitis. These findings are significant for formulating targeted prevention and treatment strategies, and hold promise for improving the clinical treatment outcomes of patients’ osteomyelitis.