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. 2010 Apr 1;184(7):3768-79.
doi: 10.4049/jimmunol.0903151. Epub 2010 Mar 3.

IL-7 promotes T cell viability, trafficking, and functionality and improves survival in sepsis

Jacqueline Unsinger  1 , Margaret McGlynn, Kevin R Kasten, Andrew S Hoekzema, Eizo Watanabe, Jared T Muenzer, Jacquelyn S McDonough, Johannes Tschoep, Thomas A Ferguson, Jonathan E McDunn, Michel Morre, David A Hildeman, Charles C Caldwell, Richard S Hotchkiss
Affiliations

IL-7 promotes T cell viability, trafficking, and functionality and improves survival in sepsis

Jacqueline Unsinger et al. J Immunol. .

Abstract

Sepsis is a highly lethal disorder characterized by widespread apoptosis-induced depletion of immune cells and the development of a profound immunosuppressive state. IL-7 is a potent antiapoptotic cytokine that enhances immune effector cell function and is essential for lymphocyte survival. In this study, recombinant human IL-7 (rhIL-7) efficacy and potential mechanisms of action were tested in a murine peritonitis model. Studies at two independent laboratories showed that rhIL-7 markedly improved host survival, blocked apoptosis of CD4 and CD8 T cells, restored IFN-gamma production, and improved immune effector cell recruitment to the infected site. Importantly, rhIL-7 also prevented a hallmark of sepsis (i.e., the loss of delayed-type hypersensitivity), which is an IFN-gamma- and T cell-dependent response. Mechanistically, rhIL-7 significantly increased the expression of the leukocyte adhesion markers LFA-1 and VLA-4, consistent with its ability to improve leukocyte function and trafficking to the infectious focus. rhIL-7 also increased the expression of CD8. The potent antiapoptotic effect of rhIL-7 was due to increased Bcl-2, as well as to a dramatic decrease in sepsis-induced PUMA, a heretofore unreported effect of IL-7. If additional animal studies support its efficacy in sepsis and if current clinical trials continue to confirm its safety in diverse settings, rhIL-7 should be strongly considered for clinical trials in sepsis.

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Conflict of interest statement

Disclosures

Dr. Michel Morre is the CEO of Cytheris Corporation, a company that makes IL-7 for clinical trials. The other authors have no financial conflicts of interest.

Figures

FIGURE 1
FIGURE 1
rhIL-7 prevents loss of CD4 and CD8 T cells in sepsis. Sham or septic mice were treated with 5 μg of rhIL-7 or diluent 90 min after surgery. Spleens were harvested for determination of absolute cell counts ~24 h later. Sepsis induced a loss in all classes of immune effector cells. rhIL-7 prevented the loss in CD4 and CD8 T cells but not in NK cells, B cells, or dendritic cells. *Sham versus CLP is significant at p < 0.01; CLP versus CLP + IL-7 is significant as indicated (n = 11 mice per group in each of the four groups; results from three combined studies).
FIGURE 2
FIGURE 2
rhIL-7 prevents sepsis-induced apoptosis of T cells. Sham or septic mice were treated with 5 μg of rhIL-7 at 90 min after surgery. Spleens were harvested 24 h later, and apoptosis was determined by the TUNEL method. rhIL-7 prevented the marked increase in CD4 and CD8 T cell apoptosis occurring during sepsis. *Sham versus CLP is significantly different at p < 0.05; p value shown in the figure compares CLP versus CLP + IL-7. (n = 6–8 mice per group in the two sham groups, and n = 11 mice per group in the two CLP groups; results from three combined studies.)
FIGURE 3
FIGURE 3
rhIL-7 increases CD4 and CD8 T cell subsets in lymph nodes. Sham or septic mice were treated with 5 μg of rhIL-7 at 90 min after surgery. Mesenteric lymph nodes were harvested 24 h later, and central memory, naive, and effector memory T cell subsets were assessed for CD4 and CD8 T cells via flow cytometry (see Materials and Methods). rhIL-7 had a significant ability to increase the absolute cell counts of CD4 central memory, naive, and effector memory T cells and CD8 central memory and effector memory T cells compared with CD4 and CD8 T cells from septic mice that did not receive rhIL-7 (n = 6 sham, n = 6 sham + rhIL-7, n = 9 CLP, and n = 10 CLP + rhIL-7; results from three combined studies). *p < 0.05.
FIGURE 4
FIGURE 4
rhIL-7 increases antiapoptotic Bcl-2 and decreases proapoptotic PUMA protein and mRNA. A, Flow cytometry of intracellular staining for Bcl-2 in CD4 T cells. Sham or septic mice were treated with 5 μg of rhIL-7 at 90 min after surgery, spleens were harvested 24 h later, and lymphocytes were stained for intracellular Bcl-2. Flow cytometry was performed for relative quantitation of Bcl-2 in CD4 T cells. rhIL-7 increased Bcl-2 in sham and CLP mice. Each curve shows data from one representative mouse. B, The level of Bcl-2 in sham mice was normalized to a value of 1.0, and the Bcl-2 in other groups was expressed relative to this value. Note the increase in Bcl-2 in sham and septic mice treated with rhIL-7 (n = 6–8 mice in each group). *Sham versus sham + rhIL-7 is significantly different at p < 0.05. A highly similar effect of rhIL-7 also occurred on CD8 T cells (see Table I); two combined studies. C, Flow histogram of four individual representative mice. Note the increase in PUMA in CLP mice and the ability of rhIL-7 to prevent the sepsis-induced increase. D, Summary data for PUMA for all mice; one independent study (n = 4–5 mice per group). E, qRT-PCR for Bcl-2 and PUMA was performed on CD4 T cells isolated from sham- or CLP-operated mice 4 h after surgery and then incubated with or without rhIL-7 (5 ng/ml) for 5 h; one independent study. Note the dramatic increase in Bcl-2 gene expression in CD4 T cells from sham- and CLP-operated mice treated with rhIL-7. F, In addition, rhIL-7 caused a decrease in PUMA expression (n = 3 sham and n = 4 CLP mice in each group; one independent study). *p < 0.01.
FIGURE 5
FIGURE 5
rhIL-7 increases cell proliferation. A, Sham or septic mice were treated with 5 μg of rhIL-7 at 90 min after surgery and again 24 and 48 h later. At 72 h after surgery, spleens were harvested, and lymphocytes were stained for the proliferation marker Ki67. rhIL-7 increased the percentage of CD4 and CD8 T cells that were positive for Ki67. rhIL-7 failed to increase proliferation in CD4 T cells in septic mice cells at 72 h but did increase proliferation in CD8 T cells. (n = 6–7 mice per group for sham and CLP; one independent study.) B, Flow cytometry dot plot showing the ability of rhIL-7 to increase proliferation, as indicated by the increase in CD8 T cells positive for Ki67. The numbers in the right upper quadrant represent the percentage of CD8 T cells positive for Ki67 (n = one representative animal per group).
FIGURE 6
FIGURE 6
IL-7R expression is increased in sepsis. Sham or septic mice were treated with 5 μg of rhIL-7 for three consecutive days and killed on the third postoperative day. Sepsis induced a marked increase in IL-7R expression in CD4 and CD8 T cells. Treatment with rhIL-7 caused a decrease in IL-7R expression in sham and septic mice (n = 4 mice for each of the four groups; one independent study). *p < 0.05; **p < 0.01; ***p < 0.001 compared to sham mice.
FIGURE 7
FIGURE 7
rhIL-7 improves survival in sepsis. A, CD-1 mice were injected with 5 μg of rhIL-7 90 min after CLP and again at 24 and 48 h. Septic control mice received the saline diluent. Survival was recorded for 7 d. Mice receiving rhIL-7 had a markedly improved survival. Results combined for two studies. B, Study design was identical to A, except that male C57BL6 mice were used. There was an increase in survival in mice treated with rhIL-7. Results combined for two studies. C, C57BL6 mice were treated with 5 μg/mouse IL-7 complexed with anti–IL-7 Ab (see Materials and Methods) administered immediately after CLP and again at 48 h postsurgery. Arrowheads indicate days of rhIL-7 injections.
FIGURE 8
FIGURE 8
rhIL-7 reverses the sepsis-induced defect in IFN-γ production. A, Mice underwent sham or CLP surgery, and selected groups were treated with 5 μg of rhIL-7 90 min after surgery. Twenty-four hours later, splenocytes were harvested, and 1 × 107 cells were plated overnight in wells with 2 ml of RPMI 1640, as described previously. Anti-CD3 and anti-CD28 was added for lymphocyte stimulation. Supernatants were obtained, and IFN-γ was measured. Splenocytes from septic mice had a marked decrease in IFN-γ compared with sham-operated mice (p < 0.01), whereas splenocytes from septic mice that were treated with rhIL-7 did not have decreased IFN-γ production and were not different from sham-operated mice (*CLP versus CLP + IL-7; p < 0.05; n = 8 or 9 mice per group; results combined for two studies). B, CLP-operated mice were treated with 5 μg of rhIL-7 or with the saline diluent. Twenty-four hours later, splenocytes were harvested, and cells were stimulated for 24 h, followed by treatment with the Golgi inhibitor monesin for an additional 4 h. Cells had surface marker staining for CD4, CD8, and CD62L, followed by intracellular INF-γ staining. The MFI of INF-γ was evaluated by flow cytometry. CD4 and CD8 T cells that were CD62Llo (effector cells) had increased INF-γ MFI (n = 4 mice per group; one independent study).
FIGURE 9
FIGURE 9
rhIL-7 increases LFA-1, VLA-4, CD4, and CD8 expression on T cells. Mice underwent sham or CLP surgery, and selected groups were treated with 5 μg of rhIL-7 90 min and 24 and 48 h after surgery. Splenocytes were harvested 72 h later and stained for (A) LFA-1 (CD11α), (B) VLA-4 (CD49d), (C) CD4, and CD8. The fold change in the MFI of the various Ags is expressed on the y-axis, with the splenocytes from the sham cells not treated with IL-7 arbitrarily assigned a value of 1.0. IL-7 caused increases in MFI in LFA-1 and VLA-4 in splenocytes from sham and septic mice, with a more prominent effect occurring in the sham mice (p < 0.05). IL-7 also caused an increase in the MFI of CD8 T cells from sham and septic mice and an increase in the MFI of CD4 T cells from sham, but not septic, mice (n = 10 sham mice, 9 sham + rhIL-7 mice, 13 CLP mice, and 12 CLP + rhIL-7 mice; results combined for two studies).
FIGURE 10
FIGURE 10
Sepsis induces a loss in the DTH response that is prevented by rhIL-7. Mice underwent sham or CLP surgery, and selected groups were treated with 2.5 μg of rhIL-7 90 min postsurgery and every 48 h for two additional doses. Four days postsurgery, mice were sensitized with trinitrophenyl (TNP). Four days after sensitization, mice had rechallenge with trinitrophenyl (footpad injection). The degree of footpad swelling was quantitated versus PBS injection (PBS internal control). rhIL-7 increased DTH in sham mice as expected. rhIL-7–treated septic mice sustained their DTH response, whereas untreated septic mice were incapable of mounting a response. Each filled circle represents one mouse (n = 5 mice per group). The horizontal line represents the mean value for each group. CLP versus CLP + rhIL-7 was statistically significant; p < 0.05. Results of one study but representative of three additional studies.
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References

    1. Angus DC, Linde-Zwirble WT, Lidicker J, Clermont G, Carcillo J, Pinsky MR. Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care. Crit Care Med. 2001;29:1303–1310. - PubMed
    1. Monneret G. How to identify systemic sepsis-induced immunoparalysis. Advances in Sepsis. 2005;4:42–49.
    1. Adib-Conquy M, Cavaillon JM. Compensatory anti-inflammatory response syndrome. Thromb Haemost. 2009;101:36–47. - PubMed
    1. Hotchkiss RS, Coopersmith CM, McDunn JE, Ferguson TA. The sepsis seesaw: tilting toward immunosuppression. Nat Med. 2009;15:496–497. - PMC - PubMed
    1. Hiramatsu M, Hotchkiss RS, Karl IE, Buchman TG. Cecal ligation and puncture (CLP) induces apoptosis in thymus, spleen, lung, and gut by an endotoxin and TNF-independent pathway. Shock. 1997;7:247–253. - PubMed

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