Changes in help T cell 1/2 cytokines and transcription factors in cytomegalovirus infected newborn mice and effectiveness of intervention with thymopentin

Abstract

Objective To observe the changes in help T cell 1/2 cytokines and transcription factors in murine cytomegalovirus (MCMV) infected newborn mice and to determine the effectiveness of intervention with thymopentin. Methods One hundred and twenty newborn BALB/c mice were randomized into a blank group, model group and thymopentin group, with 40 mice in each group. Mice in the model and thymopentin group received an intraperitoneal injection of MCMV suspension within 4–6 hours after birth at the dosage of 20 μL to and tissue culture infections dose of 104.31 U/0.1 ml, establish a systemic infection model, and the same volume of normal saline was injected into mice in the control group. Mice in the thymopentin group also received thymopentin 0.3 mg/(kg·d). On Day 3, 5, 7, 10 and 14, 8 mice in each group were sacrificed and their splenic tissues were harvested. Interferon (IFN)–γ and interleukin (IL)–10 expression in the supernatant of a splenic lymphocyte culture was assessed by enzyme–linked immunosorbent assay. T–bet/GATA–3 mRNA in splenic tissues were analyzed using reverse transcription–polymerase chain reaction. One–way ANOVA, including LSD and Dunnett T3 methods, was used for statistical analysis. Results (1) IFN–γ expression in the model and thymopentin groups peaked on Day 3, and was higher than that in the control group [(280.73±14.88), (286.03±15.44) and (149.42±5.43) pg/ml, respectively, F=183.532, P=0.000]. Expression in the thymopentin group decreased after Day 3, and increased by Day 7. At Day 14, the IFN–γ expression level in the thymopentin group was higher than that in the control and model groups [(252.33±8.33), (149.07±7.05) and (148.57±4.53) pg/ml, respectively, F=385.487, P=0.000]. (2) IL–10 expression in the model group gradually increased. By Day 14, the expression became obviously higher than that in the control and thymopentin groups [(71.19±1.50), (36.67±2.55) and (40.01±1.28) pg/ml, respectively, F=523.670,P=0.000]. IL–10 expression in the thymopentin group increased after Day 3 and decreased by Day 7. On Day 14, the expression in the thymopentin group was lower than that in the model group, but higher than that in the control group. (3) T–bet mRNA expression was obviously increased in the model and thymopentin groups. On Day 3, the expression was higher than that in the control group (relative value of gray–scale: 0.74±0.02, 0.71±0.04 and 0.30±0.01, respectively, F=741.630, P=0.000). By Day 3, the expression in the thymopentin group decreased, and gradually recovered on Day 5, and on Day 14 it was higher than that in the control and model groups (relative value of gray–scale: 0.45±0.01, 0.30±0.01 and 0.30±0.01, respectively, F=257.571, P=0.000). (4) GATA–3 mRNA expression in the model and thymopentin groups increased on Day 3, and was higher than that in the control group (relative value of gray–scale: 0.48±0.02, 0.53±0.01 and 0.33±0.01, respectively, F=345.167, P=0.000). On Day 14, the expression in the model group was higher than that in the thymopentin group, which was higher than that in the control group (relative value of gray–scale: 0.99±0.02, 0.55±0.02 and 0.34±0.01, respectively, F=1 767.505, P=0.000). Conclusions A Th1/Th2 shift may be induced in MCMV infected neonatal mice, which manifests as a state of predominant Th2 response. Thymopentin can ameliorate this situation. Key words: Cytomegatovirus infections; Thymopentin; Interferon–gamma; Interleukin–10; Transcription factors; GATA3 transcription factor