BackgroundThe etiopathogenesis of major depressive disorder （MDD） is strongly associated with neuroinflammation. MDD is a highly heterogeneous psychiatric disorder， and the disease subtyping is an essential step for the identification of biological markers. The presence of psychomotor retardation seriously affects the prognosis of MDD， whereas the underlying mechanism is not yet completely clear. A potential involvement of granulocyte colony-stimulating factor （G-CSF） and macrophage colony-stimulating factor （M-CSF） in the pathogenesis of MDD with psychomotor retardation has been suggested in previous studies， but little detailed research has been completed. ObjectiveTo analyze the correlation of plasma G-CSF and M-CSF levels with psychomotor retardation in patients with MDD， and to explore the potential biological underpinnings of psychomotor retardation in MDD. MethodsA total of 50 MDD patients who met the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders， fifth edition （DSM-5） and attended the outpatient clinics of Shanghai Mental Health Center from April 2018 to April 2019 were included. The severity of symptoms was assessed using the Hamilton Depression Scale-17 item （HAMD-17）. According to the retardation factor in HAMD-17， patients with a score of ≥8 were included in retardation group （n=22）， and those with a score below 8 were included in non-retardation group （n=28）. Another 22 age- and sex-matched healthy controls were concurrently recruited. Plasma G-CSF and M-CSF levels were measured in all subjects using Luminex liquid suspension chip technology. Spearman correlation analysis was adopted to verify the correlation of retardation factor score in HAMD-17 with plasma G-CSF and M-CSF levels in MDD patients. ResultsPlasma G-CSF levels were decreased in MDD patients compared with healthy controls ［57.34（39.24， 83.15）pg/mL vs. 71.47（61.20， 79.99）pg/mL， Z=-2.098， P<0.05］. A statistical difference was found in plasma G-CSF level ［63.92（54.60， 89.43）pg/mL vs. 47.80（33.41， 74.66）pg/mL vs. 71.47（61.20， 79.99）pg/mL， H=8.247， P=0.016］ and plasma M-CSF level ［20.05（16.05， 22.23）pg/mL vs. 13.05（11.43， 17.50）pg/mL vs. 18.95（14.59， 22.88）pg/mL， H=7.620， P=0.022］ among retardation group， non-retardation group and healthy control group. The post hoc pairwise comparisons using Bonferroni correction indicated that plasma G-CSF level was lower in non-retardation group compared with healthy control group （adjusted P<0.05）， and plasma M-CSF level was higher in retardation group compared with non-retardation group （adjusted P<0.05）. The retardation factor score in HAMD-17 was positively correlated with plasma M-CSF level in MDD patients （r=0.348， P<0.05）. ConclusionThe prevalence of psychomotor retardation in MDD patients may be related to abnormally elevated plasma M-CSF level. ［Funded by Shanghai "Science and Technology Innovation Action Plan" Project in Medical Innovation Research Field （number， 21Y11905600）； Shanghai "Science and Technology Innovation Action Plan" Project in Natural Science Field （number， 21ZR1455100）； Shanghai Mental Health Center Scientific Research Project （number， 2021-YJ02）］