Serum level of cathelicidin LL-37 is increased in euthymic patients with bipolar disorder irrespective of their cardio-metabolic status

Abstract Background Antimicrobial peptides are components of the innate immune system. Cathelicidin LL-37 plays an important role in antimicrobial defense, exerts proinflammatory effect and strongly affects the immune system functioning. Our recent study revealed that serum concentration of LL-37 is increased in patients with bipolar disorder. Objectives The aim of this study is to re-evaluate serum LL-37 levels in patients with euthymic bipolar disorder and in healthy controls, matched for anthropometric and body composition parameters. Methods 36 adult patients with euthymic bipolar disorder and 68 non-depressed adults were included into the study. Concentration of LL-37 in serum was assessed using ELISA method. Detailed anthropometric measurements, body composition and biochemical analyses were performed. Results There was a statistically significant difference (p = 0.01) in serum LL-37 level between patients with bipolar disorder (4.97 ± 7.98 ng/mL) and control subjects (1.78 ± 2.69 ng/mL). Discussion Results of this study indicate that LL-37 serum level is increased in euthymic bipolar disorder patients. We found that this increase could not be attributed to analyzed anthropometric or body composition parameters.

抗菌肽（Antimicrobial peptides）是先天免疫系统的组成成分。抗菌肽LL-37（Cathelicidin LL-37）在抗菌防御中发挥关键作用，兼具促炎效应，可显著影响免疫系统功能。本课题组前期研究显示，双相障碍（bipolar disorder）患者的血清LL-37浓度存在升高现象。本研究的目的为重新评估心境正常的双相障碍患者与按人体测量学及身体组成参数匹配的健康对照者的血清LL-37水平。本研究共纳入36例成年心境正常双相障碍患者与68例非抑郁成年人，采用酶联免疫吸附测定法（ELISA）检测血清LL-37浓度，并完成详细的人体测量学指标检测、身体组成分析及生化检验。双相障碍患者的血清LL-37水平（4.97 ± 7.98 ng/mL）与健康对照者（1.78 ± 2.69 ng/mL）之间存在统计学显著性差异（p=0.01）。本研究结果提示，心境正常的双相障碍患者血清LL-37水平升高，且该升高情况无法通过本次分析的人体测量学或身体组成参数予以解释。