scholarly journals Melanocortin 1 Receptor Deficiency in Hematopoietic Cells Promotes the Expansion of Inflammatory Leukocytes in Atherosclerotic Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
James J. Kadiri ◽  
Sina Tadayon ◽  
Keshav Thapa ◽  
Anni Suominen ◽  
Maija Hollmén ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Atherosclerotic Plaque ◽  
Cholesterol Homeostasis ◽  
Melanocortin Receptor ◽  
Hematopoietic Stem ◽  
Leukocyte Counts

Melanocortin receptor 1 (MC1-R) is expressed in leukocytes, where it mediates anti-inflammatory actions. We have previously observed that global deficiency of MC1-R signaling perturbs cholesterol homeostasis, increases arterial leukocyte accumulation and accelerates atherosclerosis in apolipoprotein E knockout (Apoe-/-) mice. Since various cell types besides leukocytes express MC1-R, we aimed at investigating the specific contribution of leukocyte MC1-R to the development of atherosclerosis. For this purpose, male Apoe-/- mice were irradiated, received bone marrow from either female Apoe-/- mice or MC1-R deficient Apoe-/- mice (Apoe-/- Mc1re/e) and were analyzed for tissue leukocyte profiles and atherosclerotic plaque phenotype. Hematopoietic MC1-R deficiency significantly elevated total leukocyte counts in the blood, bone marrow and spleen, an effect that was amplified by feeding mice a cholesterol-rich diet. The increased leukocyte counts were largely attributable to expanded lymphocyte populations, particularly CD4+ T cells. Furthermore, the number of monocytes was elevated in Apoe-/- Mc1re/e chimeric mice and it paralleled an increase in hematopoietic stem cell count in the bone marrow. Despite robust leukocytosis, atherosclerotic plaque size and composition as well as arterial leukocyte counts were unaffected by MC1-R deficiency. To address this discrepancy, we performed an in vivo homing assay and found that MC1-R deficient CD4+ T cells and monocytes were preferentially entering the spleen rather than homing in peri-aortic lymph nodes. This was mechanistically associated with compromised chemokine receptor 5 (CCR5)-dependent migration of CD4+ T cells and a defect in the recycling capacity of CCR5. Finally, our data demonstrate for the first time that CD4+ T cells also express MC1-R. In conclusion, MC1-R regulates hematopoietic stem cell proliferation and tissue leukocyte counts but its deficiency in leukocytes impairs cell migration via a CCR5-dependent mechanism.

Hematopoietic Stem Cell Differentiation Pathway in Humans Deduced From the Lineage Diversity of PNH-Type Cells in Patients with Bone Marrow Failure.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1489-1489
Author(s):  
Takamasa Katagiri ◽  
Zhirong Qi ◽  
Yu Kiyu ◽  
Naomi Sugimori ◽  
J. Luis Espinoza ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Bone Marrow Failure ◽  
Stem Cell Differentiation ◽  
Refractory Anemia ◽  
Hematopoietic Stem

Abstract Abstract 1489 Poster Board I-512 The hematopoietic stem cell (HSC) differentiation pathway in humans remains largely unknown due to the lack of an appropriate in vivo assay allowing the growth of HSCs as well as of clonal markers that enable the tracing of their progenies. Small populations of blood cells deficient in glycosylphosphatidylinositol-anchored proteins (GPI-APs) such as CD55 and CD59 are detectable in approximately 50% of patients with aplastic anemia (AA) and 15% of patients with refractory anemia (RA) of myelodysplastic syndrome defined by the FAB classification. Such blood cells with the paroxysmal nocturnal hemoglobinuria (PNH) phenotype (PNH-type cells) are derived from single PIGA mutant HSCs and their fate depends on the proliferation and self-maintenance properties of the individual HSCs that undergo PIG-A mutation by chance (Blood 2008;112:2160, Br J Haematol 2009 in press) Analyses of the PNH-type cells from a large number of patients on the diversity of lineage combination may help clarify the HSC differentiation pathway in humans because PIG-A mutant HSCs in patients with bone marrow failure appear to reflect the kinetics of healthy HSCs. Therefore, different lineages of peripheral blood cells were examined including glycophorin A+ erythrocytes (E), CD11b+ granulocytes (G), CD33+ monocytes (M), CD3+ T cells (T), CD19+ B cells (B), and NKp46+ NK cells (Nk) from 527 patients with AA or RA for the presence of CD55−CD59− cells in E and G, and CD55−CD59−CD48− cells in M,T, B, Nk with high sensitivity flow cytometry. Two hundred and twenty-eight patients (43%) displayed 0.003% to 99.1% PNH-type cells in at least one lineage of cells. The lineage combination patterns of PNH-type cells in these patients included EGM in 71 patients (31%), EGMTBNk in 43 (19%), EG in 37 (16%), T alone 14 (6%), EGMBNk in 11 (5%), G alone in 10 (4%), GM in 10 (4%), EGMNk in 7 (3%), EGMT in 7 (3%), EGMB in 6 (3%), EM in 5 (2%), EGMTB in 3 (1%), EGNk in 1 (0.4%), EGMTNk in 1 (0.4%), GMTB in 1 (0.4%), and GT in 1 (0.4%) (Table). All patterns included G or M, except for 14 patients displaying PNH-type T cells alone. No patients showed TB or TBNk patterns suggestive of the presence of common lymphoid progenitor cells. Peripheral blood specimens from 123 patients of the 228 patients possessing PNH-type cells were examined again after 3 to 10 months and all patients showed the same combination patterns as those revealed by the first examination. PIG-A gene analyses using sorted PNH-type cells from 3 patients revealed the same mutation in G and Nk for 1 patient and in G and T for 2 patients. These findings indicate that human HSCs may take a similar differentiation pathway to that of murine HSCs, the ‘myeloid-based model’ that was recently proposed by Kawamoto et al. (Nature 2008; 10:452), though the cases with PNH-type T cells alone remain to be elucidated. Table. Lineages of cells containing PNH-type cells in patients with AA or RA. The number in the parenthesis denotes the proportion of patients showing each combination pattern in the total patients possessing PNH-type cells. (+ ; presence of PNH-type cells) Disclosures No relevant conflicts of interest to declare.

MyD88-Dependent Expansion of An Immature GR-1+CD11b+ Population From Donor Bone Marrow Reduces Early Mortality After Allogeneic Hematopoietic Stem Cell Transplantation,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4011-4011
Author(s):  
Ji-Young Lim ◽  
Gyeongsin Park ◽  
Hyewon Youn ◽  
Eun-Young Choi ◽  
Dae-Chul Jeong ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cell Transplantation ◽  
Early Mortality ◽  
Hematopoietic Stem ◽  
Target Organs ◽  
Donor Bone Marrow ◽  
Donor T Cells

Abstract Abstract 4011 Graft-versus-host disease (GVHD) is a common complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells with anti-inflammatory activity. MyD88 is a cytoplasmic adaptor molecule essential for integrating and transducing the signals generated by the toll-like receptor (TLR) family. Activation of inflammatory signaling through MyD88, presumably through ligation of multiple TLRs, plays a key role in the expansion of MDSCs. We therefore investigated how the MyD88-dependent expansion of MDSCs from donor bone marrow (BM) contributes to protection of acute GVHD. To test this, we employed an intestinal GVHD murine model, C57BL/6 (H-2b) → B6D2F1 (H-2b/d), which differs at major and minor histocompatibility loci. Lethally irradiated recipient mice were transplanted with wild-type (WT) or MyD88 knock out (KO) mice T cell-depleted (TCD)-BM together with WT spleen T cells. Morbidity and mortality of GVHD was significantly worse in recipients of MyD88 KO TCD-BM with higher intestinal pathologic grading. Animals that underwent syngeneic HSCT did not show early mortality regardless of presence of MyD88 in BM, which ruled out myelosuppression-associated toxicity. The expression of Gr-1+CD11b+ in blood, mesenteric lymph nodes and liver on day 13 was significantly reduced in the recipients of MyD88 KO TCD-BM compared with those of WT TCD-BM while the percentage of donor T cells infiltrating colon and liver was significantly higher. In parallel, the percentages of donor T cells to undergo apoptosis in response to alloantigens in vivo were significantly decreased in recipients of MyD88 KO TCD-BM. Injection of MDSCs from BM of non-tumor bearing donor markedly inhibited GVHD lethality in recipients of MyD88 KO TCD-BM. Moreover, in vivo administration of lipopolysaccharide (LPS), a TLR ligand, to donor mice expanded GR-1+CD11b+ in BM with enhanced expression of MyD88 mRNA. Recipients of TCD-BM from WT mice injected LPS showed attenuated GVHD severity as measured by weight loss and survival compared to those of TCD-BM from WT mice injected diluent. In summary, MyD88-dependent expansion of GR-1+CD11b+ population from donor TCD-BM appears to be critical for survival after allo-HSCT. Incomplete expansion of GR-1+CD11b+ population in target organs correlates with decreased apoptosis and increased infiltration of donor T cells into the target organs. Disclosures: No relevant conflicts of interest to declare.

Interruption of IFNγR Signaling Results in Altered T Cell Trafficking in Vivo and Abrogation of GvHD While Maintaining a Robust Gvl Response

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 455-455
Author(s):  
Jaebok Choi ◽  
Edward Dela Ziga ◽  
Julie Ritchey ◽  
Lynne Collins ◽  
Julie Prior ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Hematopoietic Stem Cell ◽  
Cell Trafficking ◽  
Hematopoietic Stem ◽  
T Cell Trafficking ◽  
Target Organs ◽  
Donor T Cells

Abstract Abstract 455 Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for patients with relapsed/refractory leukemia, and marrow failure states such as myelodysplasia and aplastic anemia. However, allo-HSCT is complicated by allogeneic donor T cell-mediated graft-versus-host disease (GvHD) which can be life-threatening especially in recipients of unrelated or HLA-mismatched hematopoietic stem cell products. These same alloreactive donor T cells also mediate a beneficial graft-versus-leukemia (GvL) effect. Thus, the clinical goal in allo-HSCT is to minimize GvHD while maintaining GvL. Recent studies have suggested that this might be achieved by infusing regulatory T cells (Tregs) which in some preclinical models suppress GvHD-causing alloreactive donor T cells but have only limited effects on GvL-promoting alloreactive donor T cells. Unfortunately, Tregs exist in low frequency in the peripheral blood, are costly to purify and expand, and after expansion are difficult to isolate due to the lack of cell surface markers, all of which prevent their routine use in the clinic. Thus, alternative therapeutic approaches that do not require Tregs are needed. We have found that interferon gamma receptor deficient (IFNγR−/−) allogeneic donor T cells induce significantly less GvHD in both a MHC fully-mismatched (B6 (H-2b) → Balb/c (H-2d)) and a minor-mismatched (B6 (H-2b) → B6×129(H-2b)) allo-HSCT models compared to WT T cells. In addition, IFNγR−/− donor T cells maintain a beneficial GvL effect, which has been examined in both systemic leukemia and solid tumor models using luciferase-expressing A20 cells derived from Balb/c. We find that IFNγR−/− T cells migrate primarily to the spleen while WT T cells to GI tract and peripheral lymph nodes (LNs) using bioluminescence imaging (BLI), suggesting that altered T cell trafficking of IFNγR−/− T cells to GvHD target organs might be the major reason for the reduced GvHD. We further demonstrate that the IFNγR-mediated signaling in alloreactive donor T cells is required for expression of CXCR3 which has been implicated in trafficking of T cells to areas of inflammation and target organs, commonly known to be the sites of GvHD. Indeed, CXCR3−/− T cells recapitulate the reduced GvHD potential of IFNγR−/− T cells. In addition, forced overexpression of CXCR3 in IFNγR−/− T cells via retroviral transduction partially rescues the GvHD defect observed in IFNγR−/− T cells. We next examine if inhibition of IFNγR signaling using a small molecule inhibitor can recapitulate the anti-GVHD effects seen in IFNγR−/− T cells. We find that INCB018424, an inhibitor of JAK1/JAK2 which are the mediators of IFNγR signaling, blocks CXCR3 expression in vitro. Most importantly, in vivo administration of INCB018424 after allo-HSCT alters T cell trafficking and significantly reduces GvHD. Thus, the IFNγR signaling pathway represents a promising therapeutic target for future efforts to mitigate GvHD while maintaining GvL after allo-HSCT. Moreover, this pathway can be exploited in other diseases besides GvHD such as those from organ transplantation, chronic inflammatory diseases and autoimmune diseases. Disclosures: DiPersio: genzyme: Honoraria.

Interruption of the IFN γR/CXCR3 Axis Results in Altered T Cell Trafficking In Vivo and Abrogation of GvHD While Maintaining a Robust Gvl Response

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2971-2971
Author(s):  
Jaebok Choi ◽  
Edward Dela Ziga ◽  
Julie Ritchey ◽  
Julie Prior ◽  
Lynne Collins ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Hematopoietic Stem Cell ◽  
Neutralizing Antibodies ◽  
Conflicts Of Interest ◽  
Hematopoietic Stem ◽  
Target Organs ◽  
Donor T Cells

Abstract Abstract 2971 Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for patients with relapsed/refractory leukemia, and marrow failure states such as myelodysplasia and aplastic anemia. However, allo-HSCT is complicated by allogeneic donor T cell-mediated graft-versus-host disease (GvHD) which can be life-threatening especially in recipients of unrelated or HLA-mismatched hematopoietic stem cell products. These same alloreactive donor T cells also mediate a beneficial graft-versus-leukemia (GvL) effect. Thus, the clinical goal in allo-HSCT is to minimize GvHD while maintaining GvL. Recent studies have suggested that this might be achieved by infusing regulatory T cells (Tregs) which in some preclinical models suppress GvHD-causing alloreactive donor T cells but have only limited effects on GvL-promoting alloreactive donor T cells. Unfortunately, Tregs exist in low frequency in the peripheral blood, are costly to purify and expand, and after expansion are difficult to isolate due to the lack of cell surface markers, all of which prevent their routine use in the clinic. Thus, alternative therapeutic approaches that do not require Tregs are needed. Using a MHC-mismatched GvHD model, B6 (H-2b) → Balb/c (H-2d), we demonstrated that infusion of IFN γR deficient allogeneic donor T cells induce significantly less GvHD, compared to WT T cells, determined by survival (74% vs. 0 % in overall survival; p =0.0004), weight and percentages of B220+ B cells (12.4% vs. 3.8%; p =0.0205), CD3+ T cells (14.3% vs. 4.3%; p =0.0025) in blood. Of note was that the IFN γR deficient donor T cells maintained a beneficial GvL effect, which was examined in both a systemic leukemia and a solid tumor model using luciferase-expressing A20 cells derived from Balb/c. We found that IFN γR deficient donor T cells responded normally to allogeneic antigens as measured by in vitro mixed lymphocyte reaction analyses, and express similar levels of granzyme B, compared to WT T cells. However, IFN γR deficient T cells trafficked predominantly to the spleen while WT T cells trafficked to gastrointestinal tract and peripheral lymph nodes, which are major GvHD target organs, based on in vivo bioluminescence imaging. All of these findings suggest that the reduced GvHD was not due to reduced function, altered subsets or relative deficiency of allogeneic donor T cells but from modification of in vivo trafficking of IFN γR deficient donor T cells compared to WT T cells. We further demonstrated that the IFN γR-mediated signaling in alloreactive donor T cells was required for expression of CXCR3 which has been implicated in trafficking of T cells to areas of inflammation and target organs, commonly known to be the sites of GvHD. CXCR3−/− T cells demonstrated a reduction in GvHD while maintenance of the same robust GvL effect using the same MHC mismatched transplant model. Thus, the IFN γR-CXCR3 axis represents a promising therapeutic target for future efforts to mitigate GvHD while maintaining GvL after allo-HSCT. Current studies are focused on 1) whether forced expression of CXCR3 rescues the GvHD-inducing potential of IFN γR deficient donor T cells and 2) if inhibition of IFN γR signaling (IFN γR, JAK1 and/or JAK2, CXCR3 and STAT1) using both neutralizing antibodies and small molecule inhibitors can recapitulate the anti-GvHD and pro-GvL effects seen in IFN γR−/− and CXCR3−/− T cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Thrombopoietin from hepatocytes promotes hematopoietic stem cell regeneration after myeloablation

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Longfei Gao ◽  
Matthew Decker ◽  
Haidee Chen ◽  
Lei Ding
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Critical Role ◽  
Bone Marrow Niche ◽  
Hematopoietic Stem ◽  
Hematopoietic Recovery ◽  
Cellular Source ◽  
Systemic Factors

The bone marrow niche plays a critical role in hematopoietic recovery and hematopoietic stem cell (HSC) regeneration after myeloablative stress. However, it is not clear whether systemic factors beyond the local niche are required for these essential processes in vivo. Thrombopoietin (THPO) is a critical cytokine promoting hematopoietic rebound after myeloablation and its transcripts are expressed by multiple cellular sources. The upregulation of bone marrow-derived THPO has been proposed to be crucial for hematopoietic recovery and HSC regeneration after stress. Nonetheless, the cellular source of THPO in myeloablative stress has never been investigated genetically. We assessed the functional sources of THPO following two common myeloablative perturbations: 5-fluorouracil (5-FU) administration and irradiation. Using a Thpo translational reporter, we found that the liver but not the bone marrow is the major source of THPO protein after myeloablation. Mice with conditional Thpo deletion from osteoblasts and/or bone marrow stromal cells showed normal recovery of HSCs and hematopoiesis after myeloablation. In contrast, mice with conditional Thpo deletion from hepatocytes showed significant defects in HSC regeneration and hematopoietic rebound after myeloablation. Thus, systemic THPO from the liver is necessary for HSC regeneration and hematopoietic recovery in myeloablative stress conditions.

scholarly journals Thrombopoietin from hepatocytes promotes hematopoietic stem cell regeneration after myeloablation

2021 ◽  
Author(s):  
Lei Ding ◽  
Longfei Gao ◽  
Matthew Decker ◽  
Haidee Chen
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Critical Role ◽  
Bone Marrow Niche ◽  
Hematopoietic Stem ◽  
Hematopoietic Recovery ◽  
Cellular Source ◽  
Systemic Factors

The bone marrow niche plays a critical role in hematopoietic recovery and hematopoietic stem cell (HSC) regeneration after myeloablation. However, it is not clear whether systemic factors beyond the local niche are required for these essential processes in vivo. Thrombopoietin (TPO) is a critical cytokine promoting hematopoietic rebound after myeloablation and its transcripts are expressed by multiple cellular sources. The upregulation of bone marrow-derived TPO has been proposed to be crucial for hematopoietic recovery and HSC regeneration after stress. Nonetheless, the cellular source of TPO in stress has never been investigated genetically. We assessed the functional sources of TPO following two common myeloablative perturbations: 5-fluorouracil (5-FU) administration and irradiation. Using a Tpo translational reporter, we found that the liver but not the bone marrow is the major source of TPO protein after myeloablation. Mice with conditional Tpo deletion from osteoblasts or bone marrow stromal cells showed normal recovery of HSCs and hematopoiesis after myeloablation. In contrast, mice with conditional Tpo deletion from hepatocytes showed significant defects in HSC regeneration and hematopoietic rebound after myeloablation. Thus, systemic TPO from the liver is necessary for HSC regeneration and hematopoietic recovery in myeloablative stress conditions.

Jagged1-dependent Notch signaling is dispensable for hematopoietic stem cell self-renewal and differentiation

Blood ◽  
2005 ◽  
Vol 105 (6) ◽  
pp. 2340-2342 ◽  
Author(s):  
Stéphane J. C. Mancini ◽  
Ned Mantei ◽  
Alexis Dumortier ◽  
Ueli Suter ◽  
H. Robson MacDonald ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Notch Signaling ◽  
Hematopoietic Stem Cell ◽  
Stromal Cells ◽  
Essential Role ◽  
Self Renewal ◽  
Hematopoietic Stem

AbstractJagged1-mediated Notch signaling has been suggested to be critically involved in hematopoietic stem cell (HSC) self-renewal. Unexpectedly, we report here that inducible Cre-loxP–mediated inactivation of the Jagged1 gene in bone marrow progenitors and/or bone marrow (BM) stromal cells does not impair HSC self-renewal or differentiation in all blood lineages. Mice with simultaneous inactivation of Jagged1 and Notch1 in the BM compartment survived normally following a 5FU-based in vivo challenge. In addition, Notch1-deficient HSCs were able to reconstitute mice with inactivated Jagged1 in the BM stroma even under competitive conditions. In contrast to earlier reports, these data exclude an essential role for Jagged1-mediated Notch signaling during hematopoiesis.

Adoptive Transfer of In Vitro Generated T Cell Precursors Enhances Donor T Cell Reconstitution and Graft-Versus-Tumor Activity in Allogeneic Hematopoietic Stem Cell Transplantation Recipients.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 63-63 ◽  
Author(s):  
Johannes L. Zakrzewski ◽  
Adam A. Kochman ◽  
Sidney X. Lu ◽  
Theis H. Terwey ◽  
Theo D. Kim ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Stem Cell ◽  
Growth Factors ◽  
T Cell ◽  
Hematopoietic Stem Cell Transplantation ◽  
Hematopoietic Stem ◽  
T Cell Reconstitution

Abstract Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with a varying period of immunoincompetence that particularly affects he T cell lineage resulting in significant morbidity and mortality from opportunistic infections. Recent studies have shown that murine T cells and their precursors can be generated from hematopoietic stem cells (HSC) in vitro using a OP9-DL1 coculture system consisting of OP9 bone marrow stromal cells expressing the Notch 1 ligand Delta-like 1 and growth factors (interleukin 7 and fms-like tyrosine kinase-3 ligand). In this study we determined the effects of adoptively transferred in vitro generated T cell precursors on T cell reconstitution after allogeneic HSCT. We selected HSC (Lin- Sca-1hi c-kithi) from bone marrow (BM) of C57BL/6 mice and cultured these cells on a monolayer of OP9-DL1 cells in the presence of growth factors. These HSC expanded 2,000–5,000-fold within 3–4 weeks and consisted of >95% CD4-CD8-double negative (DN) T cell precursors after 16–28 days of culture. We infused these cells (8x106) with T cell depleted (TCD) BM (5x106) or purified HSC into allogeneic recipients using minor antigen mismatched and MHC class I/II mismatched transplant models. Control mice received TCD BM or purified HSC only. Progeny of OP9-DL1 derived T cell precursors were found in thymus and spleen increasing thymic cellularity and significantly improving thymic and splenic donor T cell chimerism. This effect was even more pronounced when purified HSC instead of whole BM were used as allograft. T cell receptor repertoire and proliferative response to foreign antigen (determined by third party MLR) of in vivo differentiated OP9-DL1 derived mature T cells were intact. Administration of in vitro generated T cell precursors did not induce graft-versus-host disease (GVHD) but mediated significant graft-versus-tumor (GVT) activity (determined by in vivo bioluminescence imaging) resulting in a subsequent significant survival benefit. This advantage was associated with better cytokine responses (IL-2, INF-g, TNF-a) in T cells originating from OP9-DL1 derived T cell precursors compared to BM donor derived T cells. We conclude that the adoptive transfer of OP9-DL1 derived T cell precursors significantly enhances post-transplant T cell reconstitution and GVT activity in the absence GVHD.

CD26 Inhibitor Treated and CD26−/− Recipient Mice Exhibit Improved Transplant Efficiency as Quantitated by Increased Short-Term Homing and Long-Term Engraftment

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 361-361 ◽  
Author(s):  
Laura A. Paganessi ◽  
Stephanie A. Gregory ◽  
Henry C. Fung ◽  
Kent W. Christopherson
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Mononuclear Cells ◽  
Short Term ◽  
Hematopoietic Stem ◽  
Post Transplant ◽  
Inhibitor Treatment

Abstract A firm understanding of the biology of hematopoietic stem and progenitor cell (HSC/ HPC) trafficking is believed to be critical for the development of methodologies to improve transplant efficiency and subsequently immune reconstitution during hematopoietic stem cell transplantation in the clinical setting. Through the use of CD26 inhibitors and CD26 deficient mice (CD26−/−), we have previously generated data in mice suggesting that suppression of CD26/DPPIV (dipeptidylpeptidase IV) enzymatic activity on the transplant donor cell population can be utilized as a method of increasing transplant efficiency (Christopherson, KW 2nd, et al, Science 2004. 305:1000–3). However, the clinical importance of the transplant recipient should not to be overlooked given the potential importance of the bone marrow microenvironment in regulating the transplant process. We therefore investigated here whether inhibition or loss of CD26 activity in recipient mice would have an effect on transplant efficiency utilizing an in vivo congenic mouse model of transplantation. The short-term homing and long-term engraftment of BoyJ donor cells (expressing CD45.1+) into lethally irradiated control C57BL/6, CD26 inhibitor (Diprotin A) treated C57BL/6, or CD26−/− mice (expressing CD45.2+) was monitored by flow cytometric analysis of the bone marrow and peripheral blood at 24 hours and 6 months post-transplant respectively. Twenty-four hours post-transplant of 20×106 BoyJ mononuclear cells, we observed 8.85±0.58%, 10.69±1.01%, and 12.45±1.33% donor derived Sca-1+lin− cells in the bone marrow of recipient mice for control, Diprotin A treated, and CD26−/− recipient mice respectively. As compared to control mice, this represents a 20.8% increase (p=0.01) with CD26 inhibitor treatment and a 40.7% increase (p£0.05) resulting from the use of a CD26−/− recipient in short-term homing (N=5 mice per group). Six months post-transplant of 1×105 BoyJ mononuclear cells, we observed 39.90± 4.38%, 70.22± 3.72%, and 92.51± 1.04% donor contribution to hematopoiesis in the peripheral blood of control, Diprotin A treated, and CD26−/− recipient mice respectively. This represents a 76.0% increase (p£0.01) with CD26 inhibitor treatment and a 131.9% increase (p£0.01) as a result of the CD26−/− recipient in long-term engraftment as compared to control recipient mice (N=14 mice per group). These results provide pre-clinical evidence of the importance of CD26 expression within the transplant recipient with regard to regulating hematopoietic stem cell homing and engraftment. Our results also support the potential use of CD26 inhibitors to treat transplant patients during hematopoietic stem cell transplantation as a method of improving transplant efficiency. Lastly, our use of inhibitor treated C57BL/6 and CD26−/− recipient mice, which are also on a C57BL/6 background, in conjunction with a congenic model of transplantation provides a accurate and convenient model system for the in vivo testing of the efficacy of existing and new CD26 inhibitors in transplant recipients.

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