The peripheral immune cell counts and mouth ulcers: A two-sample Mendelian randomization study

Yajing Wang; Yuanyuan Hu; Mengxuan Shen; Yang Cai; Zhiyuan Li; Changyue Xue; Xu Tan; Jukun Song

doi:10.1016/j.heliyon.2023.e23430

The peripheral immune cell counts and mouth ulcers: A two-sample Mendelian randomization study

Heliyon. 2023 Dec 7;10(1):e23430. doi: 10.1016/j.heliyon.2023.e23430. eCollection 2024 Jan 15.

Authors

Yajing Wang^{1

2}, Yuanyuan Hu^{1

2}, Mengxuan Shen^{1

2}, Yang Cai^{1

2}, Zhiyuan Li^{1

2}, Changyue Xue³, Xu Tan^{1

2}, Jukun Song^{1

2}

Affiliations

¹ The Affiliated Stomatological Hospital of Guizhou Medical University, Guizhou Medical University, Guiyang, China.
² The Stomatology of Guizhou Medical University, Guizhou Medical University, Guiyang, China.
³ Department of Implant Dentistry, Affiliated Stomatological Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.

Abstract

Objective: This study explored the causal association of peripheral immune cell counts with mouth ulcers (MUs) by two-sample Mendelian Randomization.

Design: The counts of 12 circulating immune cell types (leukocytes, lymphocytes, monocytes, eosinophils, neutrophils, basophils, CD4⁺ cells, CD8⁺ cells, unswitched memory B cells, NK cells, B cells and a derived ratio (CD4+/CD8+)) were determined as the exposure. MUs were the outcome. The analysis was conducted mostly using the inverse-variance weighted (IVW) approach. MR Egger, weighted median, weighted mode and simple mode were used to detect the horizontal pleiotropy.

Results: The IVW results for leukocytes and lymphocyte counts were OR = 0.93, 95 % CI = 0.88-0.98, p = 0.0115 and OR = 0.91, 95 % CI: 0.84-0.98, p = 0.0150, respectively. The Wald ratio result for CD4⁺ cell and CD8⁺ cell counts were OR = 0.70, 95 % CI: 0.65-0.75, p = 1.05 × 10^-20 and OR = 1.25, 95 % CI: 1.19-1.31, p = 9.99 × 10^-21, respectively.

Conclusions: This study supports a causal effect of peripheral immune cell counts on MUs. Higher leukocyte, lymphocyte and CD4⁺ cell counts can protect against MUs, but higher CD8⁺ cell counts enhance the risk of MUs. This finding confirms host immune factors play a crucial role in the aetiology of MUs.

Keywords: CD4+ cell; CD8+ cell; Lymphocyte; Mouth ulcers; Peripheral immune cell counts; Two-sample mendelian randomization (MR).