Dataset Information

Increased circulating regulatory T cells (CD4(+)CD25 (+)CD127 (-)) contribute to lymphocyte anergy in septic shock patients.

ABSTRACT:

Purpose

Sepsis syndrome represents the leading cause of death in intensive care unit. Patients present features consistent with a decline in immune responsiveness potentially contributing to mortality. We investigated whether CD4(+)CD25(+) regulatory T cells (Treg) participate in the induction of lymphocyte anergy after sepsis.

Method

Observational study in septic shock patients and experimental study in mice.

Results

We took advantage of the recently described flow cytometric gating strategy using the measurement of CD25 and CD127 expressions for monitoring Treg (CD4(+)CD25(+)CD127(-)Foxp3(+)). In patients the increased circulating Treg percentage significantly correlated with a decreased lympho-proliferative response. In a murine model of sepsis mimicking these observations, the ex vivo downregulation of Foxp3 expression using siRNA was associated with a restoration of this response.

Conclusion

The relative increase in circulating Treg might play a role in lymphocyte anergy described after septic shock and represent a standardizable surrogate marker of declining proliferative capacity after sepsis.

SUBMITTER: Venet F

PROVIDER: S-EPMC2789433 | biostudies-literature | 2009 Apr

REPOSITORIES: biostudies-literature

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Publications

Increased circulating regulatory T cells (CD4(+)CD25 (+)CD127 (-)) contribute to lymphocyte anergy in septic shock patients.

Venet Fabienne F Chung Chun-Shiang CS Kherouf Hakim H Geeraert Anne A Malcus Chistophe C Poitevin Françoise F Bohé Julien J Lepape Alain A Ayala Alfred A Monneret Guillaume G

Intensive care medicine 20081023 4

<h4>Purpose</h4>Sepsis syndrome represents the leading cause of death in intensive care unit. Patients present features consistent with a decline in immune responsiveness potentially contributing to mortality. We investigated whether CD4(+)CD25(+) regulatory T cells (Treg) participate in the induction of lymphocyte anergy after sepsis.<h4>Method</h4>Observational study in septic shock patients and experimental study in mice.<h4>Results</h4>We took advantage of the recently described flow cytomet ...[more]

PMID: 18946659

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Project description:BackgroundLipoproteins and their component apolipoproteins play an important role in sepsis. However, little is known with regard to the association and causal contribution of these proteins to mortality in patients of different ancestries following septic shock. The objective of this study was to determine whether lipoprotein and apolipoprotein levels, and related genetic variants, are associated with clinical outcomes in septic shock.MethodsWe investigated the association between lipoprotein and apolipoprotein levels at the point of admission to the intensive care unit and in-hospital mortality in 687 Japan patients diagnosed with septic shock. For each clinically significant candidate protein, we extracted haplotype tag single nucleotide polymorphisms (SNPs) of the corresponding gene and examined the association of the candidate gene variants with 28-day mortality and organ dysfunction. We tested for replication in a Caucasian septic shock cohort (Vasopressin and Septic Shock Trial, VASST, n = 474). To determine whether the candidate lipoprotein causally contributed to septic shock outcome, we used a Mendelian randomization analysis based on polygenic scores generated from a genome-wide association study (GWAS) in the Japan cohort.ResultsIn the Japan cohort, low apolipoprotein A-II levels were associated with increased septic shock mortality (adjusted odds ratio, 1.05; 95%CI, 1.02-1.09; P < 0.001). For a haplotype tag SNP of the corresponding ApoA2 gene, rs6413453 GG carriers had significantly higher 28-day mortality (adjusted hazard ratio [aHR], 1.79; 95% confidence interval [CI], 1.06-3.04; P = 0.029) and significantly fewer days free of cardiovascular, respiratory, renal and neurologic dysfunction than AG/AA carriers. This result was replicated in the Caucasian septic shock cohort (28-day mortality: aHR, 1.65; 95% CI, 1.02-2.68; P = 0.041). Mendelian randomization using 9 SNPs from an apolipoprotein A-II GWAS suggested that genetically decreased levels of apolipoprotein A-II were a causal factor for increased mortality in septic shock (odds ratio for mortality due to a 1 mg/dL decrease in apolipoprotein A-II is 1.05 [95% CI; 1.01-1.03, P = 0.0022]).ConclusionsIn septic shock, apolipoprotein A-II levels and ApoA2 genetic variations are important factors associated with outcome.

Project description:Although immunoregulation of alloreactive human CTLs has been described, the direct influence of CD4(+) Tregs on CD8(+) cytotoxicity and the interactive mechanisms have not been well clarified. Therefore, human CD4(+)CD127(-)CD25(+)FOXP3(+) Tregs were generated in MLR, immunoselected and their allospecific regulatory functions and associated mechanisms were then tested using modified (51)Chromium release assays (Micro-CML), MLRs and CFSE-based multi-fluorochrome flow cytometry proliferation assays. It was observed that increased numbers of CD4(+)CD127(-)CD25(+)FOXP3(+) cells were generated after a 7 day MLR. After immunoselection for CD4(+)CD127(-)CD25(+) cells, they were designated as MLR-Tregs. When added as third component modulators, MLR-Tregs inhibited the alloreactive proliferation of autologous PBMC in a concentration dependent manner. The inhibition was quasi-antigen specific, in that the inhibition was non-specific at higher MLR-Treg modulator doses, but non-specificity disappeared with lower numbers at which specific inhibition was still significant. When tested in micro-CML assays CTL inhibition occurred with PBMC and purified CD8(+) responders. However, antigen specificity of CTL inhibition was observed only with unpurified PBMC responders and not with purified CD8(+) responders or even with CD8(+) responders plus Non-T "APC". However, allospecificity of CTL regulation was restored when autologous purified CD4(+) T cells were added to the CD8(+) responders. Proliferation of CD8(+) cells was suppressed by MLR-Tregs in the presence or absence of IL-2. Inhibition by MLR-Tregs was mediated through down-regulation of intracellular perforin, granzyme B and membrane-bound CD25 molecules on the responding CD8(+) cells. Therefore, it was concluded that human CD4(+)CD127(-)CD25(+)FOXP3(+) MLR-Tregs down-regulate alloreactive cytotoxic responses. Regulatory allospecificity, however, requires the presence of cognate responding CD4(+) T cells. CD8(+) CTL regulatory mechanisms include impaired proliferation, reduced expression of cytolytic molecules and CD25(+) activation epitopes.

Dataset Information

Increased circulating regulatory T cells (CD4(+)CD25 (+)CD127 (-)) contribute to lymphocyte anergy in septic shock patients.

Purpose

Method

Results

Conclusion

Publications

Increased circulating regulatory T cells (CD4(+)CD25 (+)CD127 (-)) contribute to lymphocyte anergy in septic shock patients.

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