| BackgroundCommunity-Acquired Pneumonia(CAP)refers to pneumonia contracted outside a medical institution.It is a common respiratory disease with high morbidity and mortality.Sepsis is a life-threatening organ dysfunction caused by the host’s disordered immune response to infection.As one of the serious complications of CAP,sepsis is closely related to poor prognosis.Early prediction and intervention of sepsis in patients with CAP can improve their prognosis,but the current detection methods for sepsis are very limited.So it is significant to look for predictor of CAP complicated with sepsis.Immune regulation of cellular and molecular has great potential of prediction.It has been reported that the levels of regulatory T cells(Treg)and their surface molecule PD-1 change during the pathogenesis of sepsis.Dendritic cells(DC),DC’s subsets and their surface molecule CD80,CD86 and PD-L1 levels also change in sepsis.It’s also reported that inflammatory mediators such as TNF-α,IFN-y and IL-6 were involved in the formation of sepsis immune disorders.Neutrophil-to-lymphocyte ratio(NLR)is a simple and easy clinical indicator.As NLR contains the information of neutrophil and lymphocyte levels,it is considered superior to the single indicators.But there is still no study on the use of NLR in the risk prediction of sepsis in the early stage of CAP.In this study,patients with CAP were included.According to SOFA score,the patients were judged to be complicated with sepsis,and then divided into a CAP group and a CAP complicated with sepsis group.Volunteers from the health examination center at the same time were included as the control group.Flow cytometry to detect the proportion of Treg and it’s surface PD-1,the proportion of DC,the proportion and number of DC subsets,and it’s surface CD80,CD86 and PD-L1.ELISA to detect serum TNF-α,IFN-y,IL-6 and IL-10.At the same time,Clinical data were collected and the NLR was calculated and correlations of the above indicators were explored.So as to explore the correlation between the number and function of immune cells and the severity of CAP complicated with sepsis,and to use this as the basis for the prediction of CAP complicated with sepsis.Materials and methodsIn this study,30 patients admitted to the respiratory department or MICU of the General Hospital of Southern Theater Command of PLA from July 2018 to January 2020 with the first diagnosis of CAP were included and were divided into the CAP group and the CAP complicated with sepsis group according to the SOFA score.At the same time,10 volunteers from the health examination center were included as the control group.36.67%(11/30)of the CAP patients recruited in this study developed into sepsis,while 63.33%(19/30)did not.Accordingly,there were 19 patients in the CAP group,including 13 males and 6 females,with an average age of 74.42±8.853 years.There were 11 patients in the CAP complicated with sepsis group,including 8 males and 3 females,with an average age of 80.4515.733 years.The control group included 10 volunteers,7 males and 3 females,with an average age of 72.6017.947 years.There was no significant difference in age,sex and basic diseases among the three groups.3-5ml blood samples were collected within 24h after the subjects were enrolled.Flow cytometry was used to detect the proportion of tregs in peripheral blood and the expression level of surface molecule PD-1,the proportion of DC,the proportion and number of DC subsets,and it’s surface CD80,CD86 and PD-L1.Plasma separation at the same time,ELISA to detect TNF-α,IFN-y,IL-6 and IL-10 level;On the other hand,clinical data of the subjects were collected,Neutrophil absolute value(N)and Lymphocyte absolute value(L)were recorded within 24 hours upon admission,and NLR was calculated.Finally,the correlation analysis of the above indicators was carried out.Results1.Proportion of Treg in CD4+T cellsIn the CAP complicated with sepsis group,the proportion of Treg in CD4+T cells within 24 hours of admission was higher than that in the CAP group(P=0.003)and the control group(P=0.004).2.Expression of PD-1 on the Treg cell surfaceIn the CAP complicated with sepsis group,the expression of PD-1 on the Treg cell surface within 24 hours of admission was higher than that in the CAP group(P=0.000)and the control group(P=0.000).3.Levels of DC,mDC and pDCThe proportion of peripheral blood DC in PBMC within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 0.41 ±0.261(%),0.52±0.369(%)and 0.53±0.217(%),respectively,with no statistically significant difference between the three groups(P=0.568).In the CAP complicated with sepsis group,the proportion of pDC in DC was lower than that in the control group(P=0.015).And the CAP complicated with sepsis group was lower than that in CAP group,but the difference was not statistically significant(P=0.246).In the CAP complicated with sepsis group,the proportion of mDC in DC was lower than that in the CAP group(P=0.000)and the control group(P=0.000).In the CAP complicated with sepsis group,the number of pDC in 100μl whole blood was less than that of the CAP group(P=0.002)and the control group(P=0.026).In the CAP complicated with sepsis group,the number of mDC in 100μl whole blood was less than that of the CAP group(P=0.003)and the control group(P=0.003).The mDC/pDC ratios of peripheral blood in the CAP complicated with sepsis group,CAP group and control group were 5.83±5.883,10.94±15.194,and 2.73±1.722,respectively,with no statistically significant difference pairwise comparisons,4.Expressions of CD80,CD86 and PD-L1 on the surface of mDCIn the CAP complicated with sepsis group,the percentage of CD80 expression of mDC in peripheral blood within 24 hours of admission was lower than that in the CAP group(P=0.000)and the control group(P=0.000).In the CAP complicated with sepsis group,the percentage of CD86 expression was lower than that in the CAP group(P=0.000)and the control group(P=0.000).In the CAP complicated with sepsis group,the percentage of PD-L1 expression was higher than that in the CAP group(P=0.000)and the control group(P=0,001).5.Expressions of CD80,CD86 and PD-L1 on the surface of pDCIn the CAP complicated with sepsis group,the percentage of CD80 expression on the surface of pDC in peripheral blood within 24 hours of admis.sion was lower than that in the CAP group(P=0.000)and the control group(P=0.000).In the CAP complicated with sepsis group,the percentage of CD86 expression was lower than that in the CAP group(P=0.001)and the control group(P=0.002).In the CAP complicated with sepsis group,the expression percentage of PD-L1 was higher than that in the CAP group(P=0.000)and the control group(P=0.000).6.TNF-α,IFN-y,IL-6 and IL-10 levels in PlasmaThe plasma TNF-α level within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 81.39±62.882(pg/ml),76.88±37.571(pg/ml),66.26±36.008(pg/ml),respectively,there was no statistically significant difference among three groups(P=0.776).The plasma IFN-y level within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 104.09±70.497(pg/ml),96.61 ±30.546(pg/ml),and 87.54±30.850(pg/ml),respectively,and there was no statistically significant difference between the three groups(P=0.743).The plasma IL-6 level within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 43.46±41.943(pg/ml),26.53±23.645(pg/ml),18.37± 10.643(pg/ml),respectively,there was no statistically significant difference among three groups(P=0.180).The plasma IL-10 level within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 76.24±32.308(pg/ml),99.30±73.750(pg/ml),134.05±83.605(pg/ml),respectively,there was no statistically significant difference among three groups(P=0.212).The plasma IL-10/TNF-a ratio within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 1.64± 1.500,1.71 ±1.681,2.20± 1.521,there was no statistically significant difference among three groups(P=0.771).The plasma IL-10/IFN-y ratio within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 1.00±0.720,1.20±1.076,2.16± 1.928,there was no statistically significant difference among three groups(P=0.346).The plasma IL-10/IL-6 ratio within 24 hours of admission in the CAP complicated with sepsis group,CAP group and control group were 2.19±1.732,5.81 ±5.506,9.34±8.170,the difference between the three groups was statistically significant(P=0.036).Pairwise comparison was not statistically significant.7.N,L and NLR levelsIn the CAP complicated with sepsis group,the absolute value of N within 24 hours of admission was higher than that in the control group(P=0.005),the CAP group was higher than that in the control group(P=0.002).The CAP complicated with sepsis group was higher than that in the CAP group but the difference was not statistically significant(P=0.158).In the CAP complicated with sepsis group,the absolute value of L was lower than that in the CAP group(P=0.026)and the control group(P=0.006).In the CAP complicated with sepsis group,the NLR was higher than that in the CAP group(P=0.012)and the control group(P=0.002).8.Correlation analysisSpearman’s correlation analysis showed that the overall NLR level of the subjects was positively correlated with the percentage of peripheral blood Treg in CD4+T cells(r=0.611,P=0·000),negatively correlated with the percentage of pDC in DC(r=-0.546,P=0.000),negatively correlated with the percentage of mDC in DC(r=-0.333,P=0.036),but not with IL-6(r=0.150,P=0.355).ConclusionAt the early stage of admission of patients with CAP complicated with sepsis,the proportion of Treg in peripheral blood was increased and the PD-1 expression of Treg was also increased;the number of mDC and pDC were reduced,the expression of CD80 and CD86 on the surface of DC subsets were reduced,and the expression of PD-L1 on the surface of DC subsets was increased.At the early stage of admission,the NLR of patients with CAP complicated with sepsis was higher than that of patients with CAP.NLR was positively correlated with Treg and negatively correlated with DC subsets in patients complicated with sepsis at the early stage of admission in CAP.Our results suggested that when CAP is complicated with sepsis,the number and function of Treg and DC in the patients are disordered,which mediates the immune function abnormalities in the body when CAP is complicated with sepsis.And the elevation of NLR is related to the severity of CAP. |
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