Exploring Biomarkers In Major Depressive Disorder With Different Subtypes Based On Immunoinflammatory Mechanisms

Objective:Based on the immunoinflammatory mechanism,we investigated the protein levels and mRNA expression of biomarkers in patients with different subtypes of major depressive disorder(MDD),aiming to analyze the correlation between the protein levels and mRNA expression of biomarkers and the clinical characteristics of Melancholy/UnderPowered depression(MPD)and Anxiety/Somatization depression(ASD),and to identify potential biomarkers for diagnostic typing of both.Methods:A total of 107 patients with first episode/recurrent MDD admitted to the Mental Health Department of the First Hospital of Shanxi Medical University were enrolled according to the admission criteria,including 65 MPD patients and 42 ASD patients.At the same time,41 Healthy volunteers recruited from the surrounding communities during the same period were selected as Healthy control(HC)according to the exclusion criteria.Demographic data and 17-item Hamilton Depression Rating Scale(HAMD-17)were collected.On an empty stomach,5-8mL venous blood was extracted from the subjects on day 0 of inclusion.After centrifugation,the supernatant was separated from the cell layer and stored at-80℃ for testing.Enzyme-linked immunosorbent assay(ELISA)and real-time quantitative PCR detection system(RT-qPCR)were used to detect the protein expression and gene expression of the biomarkers in the peripheral blood.The assay was performed to detect the expression of high mobility group box protein 1(HMGB1),interleukin 4(IL-4),interleukin 6(IL-6),tumor necrosis factor-α(TNF-α),and interferon-α(IFN-α).All data were statistically analyzed using SPSS 26.0.The χ2 test was used for statistical data such as gender and marriage;Shapiro-Wilk test was used for normal distribution of measurement data;One-way analysis of variance(ANOVA)or Kruskal-Wallis H-test was used for comparison between groups;Bonferroni correction was used for multiple comparisons;Spearman correlation test was used for bivariate correlation analysis;ROC curve analysis of biological The Bar graphs,scatter plots,ROC curves were plotted by GraphPad Prism 8.0.The difference was considered statistically significant at P<0.05.Results:1.Comparison of demographic data and clinical characteristicsIn the detection of protein level,there was no significant difference in sex and marriage between the three groups(P>0.05).The age of MPD group was significantly lower than that of HC group.The length of schooling in ASD group was significantly lower than that in HC group.Clinical characteristics showed that HAMD-17 score,anxiety/somatization factor score,weight factor score,cognitive impairment factor score,retardation factor score and sleep disorder factor score in MPD and ASD groups were higher than those in HC group.The scores of anxiety/somatization factor in MPD group were lower than those in ASD group,while the scores of cognitive impairment factor and sleep disorder factor in MPD group were higher than those in ASD group(P<0.05)..In the detection of mRNA expression,there were no statistically significant differences in age,gender,and marriage between the three groups(P>0.05);the years of education were significantly lower in the ASD group than in the HC group(P<0.05);the clinical characteristics showed that the total HAMD-17 score,anxiety/somatization factor score,weight factor score,cognitive impairment factor score,retardation factor score,and sleep disorder factor score were higher in the MPD and ASD groups than in the HC group.The scores of weight factor,cognitive impairment factor and sleep disturbance factor in MPD group were higher than those in ASD group(P<0.05).2.Comparison of protein levels and mRNA expression levels of biomarkersOn protein level,The levels of TNF-α and IL-6 in MPD and ASD groups were higher than those in HC group(P<0.05).The levels of HMGB1 and IFN-α in MPD and ASD groups were lower than those in HC group.There was no significant difference in protein level between MPD group and ASD group(P>0.05)On mRNA expression,The mRNA expression of IL-6 in MPD group was up-regulated and significantly higher than that in HC group(P<0.05).3.Correlation between protein levels and mRNA expression levels of biomarkers and clinical featuresOn protein level,TNF-α levels in MPD and ASD groups were negatively correlated with cognitive impairment factors(P<0.05).No difference was found between the two groups in relation to biomarker protein levels and clinical symptoms.On mRNA expression,The mRNA expression of IL-6 in MPD group was negatively correlated with weight factor,and the mRNA expression of IL-4 and IFN-αwas positively correlated with anxiety/somatization factor.The mRNA expression levels of IL-6 and IFN-α in ASD group were negatively correlated with cognitive impairment factors(P<0.05).4.Multiple Logistic regression analysis of MPD and ASD biomarkersOn protein level,After controlling for sex,age,years of education and marriage,multiple Logistic regression analysis showed that abnormal levels of IFN-α and IL-6 protein were risk factors for MPD and ASD(P<0.05).On mRNA expression,After controlling for gender,age,years of education and marriage,multiple Logistic regression analysis showed that IL-6 mRNA expression was up-regulated in MPD group,which was a risk factor for MPD(P<0.05).Conclusions:1.There are immune system disorders in MPD and ASD,and the mRNA expression levels of their biomarkers are correlated with different clinical features..2.Abnormal levels of plasma IFN-α,and IL-6 are expected to distinguish MPD,ASD,and HC;IL-6 with upregulated mRNA expression might be a diagnostic biomarker for MPD.