Activation-Associated Accelerated Apoptosis of Memory B Cells in Critically Ill Patients With Sepsis.
Crit Care Med 2017;
45:875-882. [PMID:
28296810 DOI:
10.1097/ccm.0000000000002380]
[Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVE
Sepsis is life-threatening organ dysfunction due to dysregulated host responses to infection. Current knowledge of human B-cell alterations in sepsis is sparse. We tested the hypothesis that B-cell loss in sepsis involves distinct subpopulations of B cells and investigated mechanisms of B-cell depletion.
DESIGN
Prospective cohort study.
SETTING
Critical care units.
PATIENTS
Adult sepsis patients without any documented immune comorbidity.
INTERVENTIONS
None.
MEASUREMENTS AND MAIN RESULTS
B-cell subsets were quantified by flow cytometry; annexin-V status identified apoptotic cells and phosphorylation of intracellular kinases identified activation status of B-cell subsets. B cell-specific survival ligand concentrations were measured. Gene expression in purified B cells was measured by microarray. Differences in messenger RNA abundance between sepsis and healthy controls were compared. Lymphopenia present in 74.2% of patients on admission day was associated with lower absolute B-cell counts (median [interquartile range], 0.133 [0.093-0.277] 10 cells/L) and selective depletion of memory B cells despite normal B cell survival ligand concentrations. Greater apoptotic depletion of class-switched and IgM memory cells was associated with phosphorylation of extracellular signal-regulated kinases, implying externally driven lymphocyte stress and activation-associated cell death. This inference is supported by gene expression profiles highlighting mitochondrial dysfunction and cell death pathways, with enriched intrinsic and extrinsic pathway apoptosis genes.
CONCLUSIONS
Depletion of the memory B-cell compartment contributes to the immunosuppression induced by sepsis. Therapies targeted at reversing this immune memory depletion warrant further investigation.
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