In vivo labeling with 2H2O reveals a human neutrophil lifespan of 5.4 days

Abstract

IntroductionNeutrophils are indispensable for host defense. 1 In addition, these cells play a detrimental role in the pathogenesis of many acute and chronic inflammatory diseases. They can cause tissue damage through aspecific activation of their repertoire of antimicrobial mechanisms. Neutrophils also inform and shape subsequent immunity 2 and can prolong inflammation by release of cytokines 3 and chemokines. 4 There is an emerging concept that neutrophils directly influence adaptive immune responses through pathogen shuttling to draining lymph nodes, 5,6 antigen presentation, 7 and modulation of T helper 1/T helper 2 responses. 8 Along this line, neutrophils have been reported to be an important component of myeloid-derived suppressor cells mediating lymphocyte suppression in various experimental models of acute 9 and chronic inflammation. 10 Targeting neutrophils in disease has mainly been focused on limiting their damaging capacity or directing their cytotoxic machinery to tumors. 11 Their immune modulatory functions have received little attention as potential targets in inflammatory diseases. This may at least in part be due to the current paradigm that these functions are of limited importance because of the generally accepted short circulatory half-life of neutrophils. Neutrophil lifespans have mainly been assessed by determination of ex vivo lifespans in culture (Ͻ 24 hours) and by transfer studies of ex vivo-manipulated neutrophils. The latter studies showed an estimated circulating half-life of approximately 8 hours in humans. 12 Ex vivo manipulation has been shown to have dramatic effects on neutrophil redistribution in vivo. 13 In mice, half-lives of 8 to 10 hours were reported when neutrophils were labeled in vivo. 14 In contrast, ex vivo labeling in mice showed that after transfer 90% of labeled neutrophils were cleared from the circulation within 4 hours, resulting in a half-life of less than 1.5 hours. 15 These differences between in vivo and ex vivo labeling strengthen our hypothesis that neutrophil transfer experiments may lead to an underestimation of neutrophil lifespan. The activation during ex vivo manipulation has probably led to retention in the lungs, 16 liver, spleen, and bone marrow (BM), 15 which may drastically reduce their circulatory half-life. To circumvent the complications introduced by ex vivo manipulation, we labeled the neutrophil pool in vivo in healthy mice and humans by administration of 2 H 2 O in drinking water. Acquisition of label and appearance of labeled neutrophils in the circulation is characterized by (1) the rate of division in the mitotic pool (MP) in the BM, (2) the transit time of newly formed neutrophils through the postmitotic pool (PMP) in the BM, and (3) the delay in mobilization of neutrophils from the PMP to the blood. With the use of a combination of gas chromatography and mass spectrometry the fraction of 2 H-labeled adenosine in the DNA of the proliferating neutrophil pool was measured, and the kinetics of the neutrophil pool was determined. Study des...

Neutrophil transcriptional profile changes during transit from bone marrow to sites of inflammation

“…1,2,10,11,[36][37][38] Although previous studies have shown that neutrophils can undergo rapid changes in gene expression upon bacterial challenge 3,4,12,13,39 or exposure to endotoxin, 3,4,10,40 it was previously unknown if and to what extent the neutrophil alters its transcriptome as it transits from the BM through the circulation and into sites of inflammation.…”

Angiotensin converting enzyme inhibitors and angiotensin II receptor antagonist attenuate tumor growth via polarization of neutrophils toward an antitumor phenotype

“…Splenic neutrophils were isolated from either control tumor-bearing mice or captopril (50 mg/kg/ d)-treated tumor-bearing mice, and exposed to CD4 C CD25 ¡ lymphocytes with anti-CD3, anti-CD28, IL-2, and TGF-b1 as previously described. 25 Since neutrophils are dying cells and the half-life of neutrophils with ex vivo manipulation is thought to be less than 24 h, 26 we examined the effect of Ly6G C cells on iTreg induction within Ly6G C cells from control tumor-bearing mice or captopril-treated tumor-bearing mice were isolated and exposed to 4T1 cells at a ratio of 10:1 for 18 h. (E) Effects of captopril on Ly6G C cells from naive mice. Blood, bone marrow, and splenic Ly6G C cells were isolated from naive mice and exposed to 500 mM captopril for 4 h, and then mean lobe counts were measured.…”

Changing world of neutrophils

“…However, various stimuli, such as cytokines (G-CSF, GM-CSF) and bacterial products were shown to prolong their survival [23]. Most recent in vivo measurements estimate an extended half-life up to 5 days for circulating neutrophils [83], although there had been concerns about these data [64].…”