About 20–40 % of autistic people experience a phenomenon of regression. Retinol binding protein 4 (RBP4) plays an important role as an inflammatory neurotrophic adipokine and is a promising mediator of the fat-brain axis. Abnormal fatty acid metabolism and lipid mediators have been reported to be related to the etiological mechanism in autism, and amelioration of impaired lipid metabolism can be recognized as a treatment strategy for autism. The purpose of this study is to explore the relationship between RBP4, lipids, and the autistic regression phenomenon, and to discuss their potentials as biomarkers for the autistic regression phenomenon. A total of 60 autistic individuals (18 with regression phenomenon, 42 without regression phenomenon) (ASD group) and 36 healthy controls were enrolled in this case-control study. The levels of RBP4, total cholesterol (TC), high-density lipoprotein (HDLC), low–density lipoprotein (LDLC), and triglyceride (TG) were measured. Childhood Autism Rating Scale (CARS) is used to assess the severity of autism. Ethical measures were performed in compliance with the current Declaration of Helsinki and written informed consent was obtained from the parents before enrollment of the children and adolescents. Compared with control subjects, autistic individuals had lower levels of TC (P = 0.007), RBP4 (P = 0.001), and HDLC (P = 0.027). The levels of RBP4 in ASD group were positively correlated with TG (r = 0.355, P = 0.005), HDLC (r = 0.257, P = 0.047), TG/TC (r = 0.376, P = 0.003) and TG/LDLC (r = 0.363, P = 0.004), and were negatively correlated with CARS (r=-0.296, P = 0.003). Further logistic regression demonstrated that decreased RBP4 concentration was associated with the presentation of the autistic regression phenomenon even after the adjustment of the potential confounding factors. Serum RBP4 is associated with the autistic regression phenomenon and the severity of ASD. Further studies are needed to expound whether decreased RBP4 participates in the development of the autistic regression phenomenon.

中文翻译：

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视黄醇结合蛋白4与脂质联合预测自闭症谱系障碍的消退现象

大约 20-40% 的自闭症患者会出现退化现象。视黄醇结合蛋白 4 (RBP4) 作为一种炎症性神经营养性脂肪因子发挥着重要作用，并且是一种有前途的脂肪脑轴介质。据报道，异常的脂肪酸代谢和脂质介质与自闭症的病因机制有关，改善脂质代谢受损可被认为是自闭症的治疗策略。本研究的目的是探讨 RBP4、脂质和自闭症消退现象之间的关系，并讨论它们作为自闭症消退现象的生物标志物的潜力。本病例对照研究共纳入60名自闭症个体（18名有退化现象，42名无退化现象）（ASD组）和36名健康对照者。RBP4 的水平，测量了总胆固醇（TC）、高密度脂蛋白（HDLC）、低密度脂蛋白（LDLC）和甘油三酯（TG）。儿童自闭症评定量表（CARS）用于评估自闭症的严重程度。道德措施是按照当前的赫尔辛基宣言进行的，并在儿童和青少年入学前获得了父母的书面知情同意。与对照组相比，自闭症个体的 TC (P = 0.007)、RBP4 (P = 0.001) 和 HDLC (P = 0.027) 水平较低。ASD组RBP4水平与TG（r=0.355，P=0.005）、HDLC（r=0.257，P=0.047）、TG/TC（r=0.376，P=0.003）、TG/LDLC（ r = 0.363, P = 0.004)，与 CARS 呈负相关 (r=-0.296, P = 0.003)。进一步的逻辑回归表明，即使在调整了潜在的混杂因素之后，RBP4 浓度的降低也与自闭症回归现象的表现相关。血清 RBP4 与自闭症消退现象和 ASD 的严重程度有关。需要进一步的研究来阐明 RBP4 降低是否参与自闭症消退现象的发展。