Sacchinelli Eleonora, Piras Fabrizio, Orfei Maria Donata, Banaj Nerisa, Salani Francesca, Ciaramella Antonio, Caltagirone Carlo, Spalletta Gianfranco, Bossù Paola
Experimental Neuropsychobiology Laboratory, IRCCS Santa Lucia Foundation, Rome,
Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy.
Neuroimmunomodulation. 2018;25(3):129-137. doi: 10.1159/000492030. Epub 2018 Oct 16.
Interaction between the nervous and immune systems may influence emotions, ultimately affecting human health. Cytokines may play a role in developing emotional dysregulation as in alexithymia, a personality construct characterized by the subclinical inability to identify and describe emotions, often associated with several psychiatric and psychosomatic disorders. The proinflammatory cytokine IL-18, with a recognized role in brain functions, may influence serotonin metabolism and appears to be associated with alexithymia. Healthy individuals carrying the long allele (L) of the serotonin transporter gene polymorphic region (5-HTTLPR), and thus having lower concentrations of serotonin in the synaptic cleft, show a greater tendency toward alexithymia, with some gender differences. To explore a potential physiological interaction between IL-18, serotonin neurotransmission, and alexithymia, we investigated whether IL-18 serum levels and 5-HTTLPR are linked to alexithymic traits in healthy subjects.
We measured IL-18 serum levels in 115 Italian-Caucasian healthy subjects genotyped for 5-HTTLPR allele variants, divided by gender and assessed for alexithymia scores using the 20-item Toronto Alexithymia Scale.
IL-18 levels are significantly more elevated in individuals with the LL genotype (n = 25) than in carriers of the short allele (n = 90, p = 0.0073). Specifically, in LL males (n = 11), i.e., the group with the most relevant increase in IL-18, cytokine values positively correlated with difficulty identifying feelings, which is a component of alexithymia (r = 0.634, p = 0.036).
These results indicate a possible novel interaction between IL-18 and the serotoninergic system to mediate emotional unawareness, suggesting putative biological predictors of emotional dysregulation, which in turn can act as a risk factor for a variety of medical conditions in susceptible subjects.
神经与免疫系统之间的相互作用可能会影响情绪，最终影响人类健康。细胞因子可能在情绪失调的发展中发挥作用，如述情障碍，这是一种人格特质，其特征为在亚临床水平上无法识别和描述情绪，常与多种精神和身心疾病相关。促炎细胞因子白细胞介素 - 18（IL - 18）在脑功能中具有公认的作用，可能会影响血清素代谢，并且似乎与述情障碍有关。携带血清素转运体基因多态性区域（5 - HTTLPR）长等位基因（L）的健康个体，其突触间隙中的血清素浓度较低，表现出更强的述情障碍倾向，且存在一些性别差异。为了探究IL - 18、血清素神经传递和述情障碍之间潜在的生理相互作用，我们调查了健康受试者中IL - 18血清水平和5 - HTTLPR是否与述情障碍特征相关。
我们测量了115名意大利 - 高加索健康受试者的IL - 18血清水平，这些受试者针对5 - HTTLPR等位基因变体进行了基因分型，按性别划分，并使用20项多伦多述情障碍量表评估述情障碍得分。
LL基因型个体（n = 25）的IL - 18水平显著高于短等位基因携带者（n = 90，p = 0.0073）。具体而言，在LL男性（n = 11）中，即IL - 18升高最为显著的组，细胞因子值与识别情感的困难程度呈正相关，识别情感困难是述情障碍的一个组成部分（r = 0.634，p = 0.036）。
这些结果表明IL - 18与血清素能系统之间可能存在一种新的相互作用，以介导情绪无意识，提示情绪失调的假定生物学预测指标，这反过来又可能成为易感个体患多种疾病的危险因素。
