[A study of lymphocyte apoptosis and endoplasmic reticulum stress in the development of sepsis and their association with outcome in septic patients].

OBJECTIVE

To investigate the role of lymphocyte apoptosis and endoplasmic reticulum stress (ERS) on the development of sepsis and their association with the prognosis of sepsis patients.

METHODS

A prospective cohort study was conducted. Seventy septic patients admitted to intensive care unit (ICU) of Shanghai East Hospital of Tongji University were enrolled. Blood samples were collected on days 1, 3 and 7 to measure percentage of circulating apoptotic lymphocyte with flow cytometry analysis. The relative expressions of endoplasmic reticulum specific glucose regulated protein 78 (GRP78) mRNA and transcription factor CHOP mRNA were measured by real-time reverse transcription-polymerase chain reaction (RT-PCR). The correlation between CHOP mRNA expression and percentage of circulating apoptotic lymphocyte was analyzed by Spearman relative analysis. The patients were divided into death (n = 23) and survival subgroups (n = 47). Twenty healthy volunteers during the same period were selected as the healthy control group.

RESULTS

(1) Rate of lymphocyte apoptosis: compared with healthy control group [(2.86±0.66)%], septic patients, either survival or death subgroup, exhibited higher rate of lymphocyte apoptosis on days 1, 3 and 7 [survival subgroup: (12.44±4.43)%, (8.57±3.38)%, (6.78±3.35)%; death subgroup: (14.42±2.01)%, (11.32±2.53)%, (8.87±3.62)%, all P < 0.01], and it was obvious on day 1, and the phenomenon became less marked gradually. The rate of circulating apoptotic lymphocytes did not differ between the death and survival subgroups on day 1, but there was a significant difference in the rate on day 3 and day 7 (both P < 0.05). (2) The expression of CHOP mRNA (2(-ΔΔCt)): compared with that in healthy controls [(2.56±1.09)×10-3], CHOP mRNA expression was increased on days 1, 3 and 7 in septic patients [survival subgroup: (5.83±1.96)×10(-3), (4.24±1.60)×10(-3), (4.15±1.64)×10(-3), death subgroup: (37.20±20.70)×10(-3), (18.80±13.90)×10(-3), (9.28±7.78)×10(-3), all P < 0.01], and it was more obvious in the death subgroup, as it was increased by 6.38, 4.43, and 2.24 folds (P values was 0.000, 0.000, and 0.001), but it decreased rapidly in death subgroup. (3) The expression of GRP78 mRNA (2(-ΔΔCt)): compared with healthy controls [(3.31±2.04)×10(-3)], the expression of GRP78 mRNA in both survival and death subgroups increased in septic patients on day 1 [(5.83±2.00)×10-3, (11.30±6.48)×10(-3), both P < 0.01], and they decreased subsequently. The expression of GRP78 mRNA in the survival subgroup declined to the levels of the healthy control group on day 3 and day 7 [3 days: (3.99±1.60)×10(-3), 7 days: (3.30±1.35)×10(-3), both P > 0.05], and GRP78 mRNA expression in the death subgroup was gradually lowered, but it was still higher than that in the healthy control group [3 days: (7.27±3.64)×10(-3), 7 days: (5.23±1.94)×10(-3), both P < 0.01]. (4) Spearman relative analysis showed that the expression of CHOP mRNA was positively correlated with the rate of lymphocyte apoptosis (r = 0.414, P = 0.000).

CONCLUSIONS

The increase in the rate of lymphocyte apoptosis and activation of ERS play an important role in the development of sepsis, and it is associated with worse outcome in the septic patients.