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Partial depletion of regulatory T cells does not influence the inflammation caused by high dose hemi-body irradiation.

Ma S, Richardson JA, Bitmansour A, Solberg TD, Pidikiti R, Song K, Stojadinovic S, Vitetta ES, Meyer JJ - PLoS ONE (2013)

Bottom Line: HBI significantly decreased the leukocyte pool though the various leukocyte subsets had different sensitivities to HBI.The administration of PC61 significantly decreased the proportion of Treg cells in spleen, iLN, mLN and blood (reduction of approximately 60%).The same general patterns were observed whether or not Treg cells were partially depleted with PC61 prior to HBI.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.

ABSTRACT
There is clinical interest in the modulation of regulatory T cells for cancer therapy. The safety of these therapies in combination with conventional anti-cancer therapies, including radiation therapy, can be studied in animal models. The effects of partial depletion of regulatory T (Treg) cells with an anti-CD25 antibody in conjunction with ionizing radiation on inflammation and tissue injury were analyzed in C57BL/6 mice. An anti-CD25 antibody (PC61) was administered 3 days prior to 13 Gy lower-half hemi-body irradiation (HBI). The blood, spleen, mesenteric lymph nodes (mLNs) and inguinal lymph nodes (iLNs) were harvested at various times thereafter. Alterations in the proportion of leukocyte subsets including CD4(+) T cells, CD8(+) T cells, Treg cells, B cells, NK cells, NK1.1(+) T cells, macrophages and granulocytes were analyzed by FACS. The lungs, liver, pancreas, stomach, jejunum, duodenum, ileum, colon and kidney were harvested and studied by H&E staining. Expression of inflammatory mediators in plasma and tissue were investigated by ELISA. HBI significantly decreased the leukocyte pool though the various leukocyte subsets had different sensitivities to HBI. The administration of PC61 significantly decreased the proportion of Treg cells in spleen, iLN, mLN and blood (reduction of approximately 60%). Irradiation significantly increased the proportion of Treg cells in the spleen, iLN and mLN. HBI induced a systemic inflammatory reaction as demonstrated by increased plasma levels of IL-6, KC/CXCL1 and circulating granulocytes in the blood. Neutrophils also infiltrated the small bowel. The same general patterns were observed whether or not Treg cells were partially depleted with PC61 prior to HBI. These data demonstrate that partial depletion of Treg cells in these mice does not influence HBI-induced inflammatory response and tissue injury, and that combining anti-CD25 therapy with radiation may be safe and well tolerated in a clinical setting.

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Treatment Schedules.(A) Schedule for Treg cell depletion and irradiation. Three days prior to irradiation, mice were administered 0.75 mg PC61 to deplete Treg cells. On day 0, mice were irradiated to 13 Gy to the lower-half hemi-body (hemi-body irradiation: HBI). Mice were sacrificed at 4 hrs, 1, 3, 7 and 14 days after radiation exposure. (B) Irradiation target: the abdomen and pelvis of mice.
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pone-0056607-g001: Treatment Schedules.(A) Schedule for Treg cell depletion and irradiation. Three days prior to irradiation, mice were administered 0.75 mg PC61 to deplete Treg cells. On day 0, mice were irradiated to 13 Gy to the lower-half hemi-body (hemi-body irradiation: HBI). Mice were sacrificed at 4 hrs, 1, 3, 7 and 14 days after radiation exposure. (B) Irradiation target: the abdomen and pelvis of mice.

Mentions: C57BL/6 mice were randomized into four groups: (i) Control: Sham HBI+0.75 mg Rat IgG, (ii) Treg cell depletion: Sham HBI+0.75 mg PC61, (iii) Radiation: 13 Gy HBI+0.75 mg Rat IgG, (iv) Radiation plus Treg cell depletion: 13 Gy HBI+0.75 mg PC61. Treg cells were depleted with a single i.p. injection 0.75 mg of PC61 MAb on day −3 [20]. Control groups received an i.p. injection of 0.75 mg normal Rat IgG at identical time points (Figure 1A).


Partial depletion of regulatory T cells does not influence the inflammation caused by high dose hemi-body irradiation.

Ma S, Richardson JA, Bitmansour A, Solberg TD, Pidikiti R, Song K, Stojadinovic S, Vitetta ES, Meyer JJ - PLoS ONE (2013)

Treatment Schedules.(A) Schedule for Treg cell depletion and irradiation. Three days prior to irradiation, mice were administered 0.75 mg PC61 to deplete Treg cells. On day 0, mice were irradiated to 13 Gy to the lower-half hemi-body (hemi-body irradiation: HBI). Mice were sacrificed at 4 hrs, 1, 3, 7 and 14 days after radiation exposure. (B) Irradiation target: the abdomen and pelvis of mice.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569437&req=5

pone-0056607-g001: Treatment Schedules.(A) Schedule for Treg cell depletion and irradiation. Three days prior to irradiation, mice were administered 0.75 mg PC61 to deplete Treg cells. On day 0, mice were irradiated to 13 Gy to the lower-half hemi-body (hemi-body irradiation: HBI). Mice were sacrificed at 4 hrs, 1, 3, 7 and 14 days after radiation exposure. (B) Irradiation target: the abdomen and pelvis of mice.
Mentions: C57BL/6 mice were randomized into four groups: (i) Control: Sham HBI+0.75 mg Rat IgG, (ii) Treg cell depletion: Sham HBI+0.75 mg PC61, (iii) Radiation: 13 Gy HBI+0.75 mg Rat IgG, (iv) Radiation plus Treg cell depletion: 13 Gy HBI+0.75 mg PC61. Treg cells were depleted with a single i.p. injection 0.75 mg of PC61 MAb on day −3 [20]. Control groups received an i.p. injection of 0.75 mg normal Rat IgG at identical time points (Figure 1A).

Bottom Line: HBI significantly decreased the leukocyte pool though the various leukocyte subsets had different sensitivities to HBI.The administration of PC61 significantly decreased the proportion of Treg cells in spleen, iLN, mLN and blood (reduction of approximately 60%).The same general patterns were observed whether or not Treg cells were partially depleted with PC61 prior to HBI.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.

ABSTRACT
There is clinical interest in the modulation of regulatory T cells for cancer therapy. The safety of these therapies in combination with conventional anti-cancer therapies, including radiation therapy, can be studied in animal models. The effects of partial depletion of regulatory T (Treg) cells with an anti-CD25 antibody in conjunction with ionizing radiation on inflammation and tissue injury were analyzed in C57BL/6 mice. An anti-CD25 antibody (PC61) was administered 3 days prior to 13 Gy lower-half hemi-body irradiation (HBI). The blood, spleen, mesenteric lymph nodes (mLNs) and inguinal lymph nodes (iLNs) were harvested at various times thereafter. Alterations in the proportion of leukocyte subsets including CD4(+) T cells, CD8(+) T cells, Treg cells, B cells, NK cells, NK1.1(+) T cells, macrophages and granulocytes were analyzed by FACS. The lungs, liver, pancreas, stomach, jejunum, duodenum, ileum, colon and kidney were harvested and studied by H&E staining. Expression of inflammatory mediators in plasma and tissue were investigated by ELISA. HBI significantly decreased the leukocyte pool though the various leukocyte subsets had different sensitivities to HBI. The administration of PC61 significantly decreased the proportion of Treg cells in spleen, iLN, mLN and blood (reduction of approximately 60%). Irradiation significantly increased the proportion of Treg cells in the spleen, iLN and mLN. HBI induced a systemic inflammatory reaction as demonstrated by increased plasma levels of IL-6, KC/CXCL1 and circulating granulocytes in the blood. Neutrophils also infiltrated the small bowel. The same general patterns were observed whether or not Treg cells were partially depleted with PC61 prior to HBI. These data demonstrate that partial depletion of Treg cells in these mice does not influence HBI-induced inflammatory response and tissue injury, and that combining anti-CD25 therapy with radiation may be safe and well tolerated in a clinical setting.

Show MeSH
Related in: MedlinePlus