Biomedical subjects

Ronald E Gress

Publications and source records attributed to Ronald E Gress.

At least 19 recordsLinked to original sources

PubMed2007

Lymphoid reconstruction and vaccines.

Allogeneic HSCT is the most reliable, robust, and effective cell-based biotherapy currently available to pediatric and adult patients with hematologic malignancies. The central role of donor-derived lymphocytes in mediating an effective antitumor effect, preventing and controlling opportunistic infections, and causing GVHD is well documented in animal experiments and human trials. The profound lymphopenia after conditioning regimens coupled with molecular tools to distinguish host versus donor cells provides investigators a window into immune recovery after allogeneic HSCT. Serial analyses of T cell subsets linking immunophenotype with function have revealed the kinetics of donor-derived T cell recovery after allografting and provided insights into ways the immune system can be manipulated to augment the graft-versus-tumor (GVT) effect without inducing GVHD. As this review demonstrates, investigators are not limited to being passive observers of this immune reconstitution; rather, we have an opportunity to shape the allografted T cells repertoire to selectively augment immune function.

Graft vs Host Disease↗

PubMed2006

Synergism between CpG-containing oligodeoxynucleotides and IL-2 causes dramatic enhancement of vaccine-elicited CD8+ T cell responses.

Novel anticancer vaccination regimens that can elicit large numbers of Ag-specific T cells are needed. When we administered therapeutic vaccines containing the MHC class I-presented self-peptide tyrosinase-related protein (TRP)-2(180-188) and CpG-containing oligodeoxynucleotides (CpG ODN) to mice, growth of the TRP-2-expressing B16F1 melanoma was not inhibited compared with growth in mice that received control vaccinations. When we added systemic IL-2 to the TRP-2(180-188) plus CpG ODN vaccines, growth of B16F1 was inhibited in a CD8-dependent, epitope-specific manner. Vaccines containing TRP-2(180-188) without CpG ODN did not cause epitope-specific tumor growth inhibition when administered with IL-2. The antitumor efficacy of the different regimens correlated with their ability to elicit TRP-2(180-188)-specific CD8+ T cell responses. When we administered TRP-2(180-188) plus CpG ODN-containing vaccines with systemic IL-2, 18.2% of CD8+ T cells were specific for TRP-2(180-188). Identical TRP-2(180-188) plus CpG ODN vaccines given without IL-2 elicited a TRP-2(180-188)-specific CD8+ T cell response of only 1.1% of CD8+ T cells. Vaccines containing TRP-2(180-188) without CpG ODN elicited TRP-2(180-188)-specific responses of 2.8% of CD8+ T cells when administered with IL-2. There was up to a 221-fold increase in the absolute number of TRP-2(180-188)-specific CD8+ T cells when IL-2 was added to TRP-2(180-188) plus CpG ODN-containing vaccines. Peptide plus CpG ODN vaccines administered with IL-2 generated epitope-specific CD8+ T cells by a mechanism that depended on endogenous IL-6. This is the first report of synergism between CpG ODN and IL-2. This synergism caused a striking increase in vaccine-elicited CD8+ T cells and led to epitope-specific antitumor immunity.

Animals↗

PubMed2006

Dysregulation of IL-15-mediated T-cell homeostasis in TGF-beta dominant-negative receptor transgenic mice.

T-cell subpopulations, defined by their expression of CD4, CD8, naive, and memory cell-surface markers, occupy distinct homeostatic compartments that are regulated primarily by cytokines. CD8+ memory T cells, as defined by CD44(hi) surface expression, are dependent on IL-15 as a positive regulator of their homeostatic maintenance. Manipulation of IL-15 signaling through gene aberration, overexpression, or receptor alterations has been shown to dramatically affect T-cell homeostasis, with overexpression leading to fatal leukemia. Here we show that TGF-beta is the critical negative regulator of murine CD8+ memory T-cell homeostasis with direct opposition to the positive effects of IL-15. This negative regulation is mediated, at least in part, by the ability of TGF-beta to modulate expression of the beta-chain of the IL-15 receptor, thus establishing a central axis between these 2 cytokines for homeostatic control of CD8+ memory T-cell populations. These data establish TGF-beta as a critical and dominant tumor-suppressor pathway opposing IL-15-mediated CD8+ T-cell expansion and potential malignant transformation.

Adoptive Transfer↗

PubMed2006

B7+ iris pigment epithelium induce CD8+ T regulatory cells; both suppress CTLA-4+ T cells.

Ocular pigment epithelia contribute to immune privilege by suppressing T cell activation and converting T cells into regulatory T regulatory cells (Tregs) that inhibit bystander T cell activation. Iris pigment epithelium (IPE) does so through direct cell-cell contact with naive T cells, and this suppressive contact is via interactions between B7 expressed constitutively on IPE cells and CTLA-4 expressed on a subpopulation of CD8+ T cells. We have now examined whether TGFbeta is required in this process. We report that IPE produces both soluble and membrane-bound active TGFbeta, but that only the latter is actually delivered to CD8+ T cells. In turn, these T cells become IPE Tregs by up-regulating their own expression of B7-1/B7-2 and soluble and membrane-bound TGFbeta. IPE Tregs through their expression of B7 are able to engage CTLA-4+ bystander T cells, and thus precisely, target delivery of membrane-bound TGFbeta. We propose that this mechanism of suppression via TGFbeta ensures that soluble active TGFbeta is not released into the ocular microenvironment where it can have unregulated and deleterious effects, including elevation of intraocular pressure and development of glaucoma.

Animals↗

PubMed2006

Phase I clinical trial of costimulated, IL-4 polarized donor CD4+ T cells as augmentation of allogeneic hematopoietic cell transplantation.

The primary objective of this clinical trial was to evaluate the safety, feasibility, and biologic effects of administering costimulated, interleukin (IL)-4 polarized donor CD4(+) T cells in the setting of HLA-matched sibling, T cell-replete allogeneic hematopoietic cell transplantation (HCT). Forty-seven subjects with hematologic malignancy received granulocyte colony-stimulating factor-mobilized allogeneic hematopoietic cell transplants and cyclosporine graft-versus-host disease (GVHD) prophylaxis after reduced intensity conditioning. Initial subjects received no additional cells (n = 19); subsequent subjects received additional donor CD4(+) T cells generated ex vivo by CD3/CD28 costimulation in medium containing IL-4 and IL-2 (administered day 1 after HCT at 5, 25, or 125 x 10(6) cells/kg). Studies after HCT included measurement of monocyte IL-1alpha and tumor necrosis factor alpha, detection of T cells with antitumor specificity, and characterization of T cell cytokine phenotype. The culture method generated donor CD4(+) T cells that secreted increased T helper 2 (Th2) cytokines and decreased T helper 1 (Th1) cytokines. Such Th2-like cells were administered without infusional or dose-limiting toxicity. The Th2 cohort had accelerated lymphocyte reconstitution; both cohorts had rapid hematopoietic recovery and alloengraftment. Acute GVHD and overall survival were similar in the Th2 and non-Th2 cohorts. Th2 cell recipients tended to have increased monocyte IL-1alpha and had increased tumor necrosis factor alpha secretion. CD8(+) T cells with antitumor specificity were observed in Th2 and non-Th2 cohorts. Post-transplantation T cells from Th2 cell recipients secreted IL-4 and IL-10 (Th2 cytokines) and IL-2 and interferon gamma (Th1 cytokines). Allograft augmentation with costimulated, IL-4-polarized donor CD4(+) T cells resulted in activated Th1, Th2, and inflammatory cytokine pathways without an apparent increase in GVHD.

Adult↗

PubMed2005

Human CD69 associates with an N-terminal fragment of calreticulin at the cell surface.

CD69 is thought to be a pluripotent signaling molecule expressed on the surface of a number of activated leukocytes including B, T, and NK cells, monocytes, neutrophils, and platelets. While some advances have been made regarding the mechanisms by which CD69 may participate in such diverse functions as cell aggregation, cellular cytotoxicity, and release of cytokines and inflammatory mediators, the most proximal links of signal initiation have not been identified. Our study has identified, by immunoprecipitation and direct protein sequencing (LC/MS/MS), binding of CD69 to an N-terminal protein fragment of calreticulin expressed on the cell surface of human PBMCs. Given the recently identified roles calreticulin plays in cell adhesion and angiogensis, the identification of CD69 binding directly to calreticulin may provide insights into mechanism(s) by which CD69 or other CD69 family members, i.e., LLT1 and AICL participates in such diverse functions.

Amino Acid Sequence↗

PubMed2005

TGF-{beta}-dependent CD103 expression by CD8(+) T cells promotes selective destruction of the host intestinal epithelium during graft-versus-host disease.

Destruction of the host intestinal epithelium by donor effector T cell populations is a hallmark of graft-versus-host disease (GVHD), but the underlying mechanisms remain obscure. We demonstrate that CD8(+) T cells expressing CD103, an integrin conferring specificity for the epithelial ligand E-cadherin, play a critical role in this process. A TCR transgenic GVHD model was used to demonstrate that CD103 is selectively expressed by host-specific CD8(+) T cell effector populations (CD8 effectors) that accumulate in the host intestinal epithelium during GVHD. Although host-specific CD8 effectors infiltrated a wide range of host compartments, only those infiltrating the intestinal epithelium expressed CD103. Host-specific CD8 effectors expressing a TGF-beta dominant negative type II receptor were defective in CD103 expression on entry into the intestinal epithelium, which indicates local TGF-beta activity as a critical regulating factor. Host-specific CD8 effectors deficient in CD103 expression successfully migrated into the host intestinal epithelium but were retained at this site much less efficiently than wild-type host-specific CD8 effectors. The relevance of these events to GVHD pathogenesis is supported by the finding that CD103-deficient CD8(+) T cells were strikingly defective in transferring intestinal GVHD pathology and mortality. Collectively, these data document a pivotal role for TGF-beta-dependent CD103 expression in dictating the gut tropism, and hence the destructive potential, of CD8(+) T cells during GVHD pathogenesis.

Animals↗

PubMed2005

Age-dependent incidence, time course, and consequences of thymic renewal in adults.

Homeostatic regulation of T cells involves an ongoing balance of new T cell generation, peripheral expansion, and turnover. The recovery of T cells when this balance is disrupted provides insight into the mechanisms that govern homeostasis. In a long-term, single cohort study, we assessed the role of thymic function after autologous transplant in adults, correlating serial computed tomography imaging of thymic size with concurrent measurements of peripheral CD4(+) T cell populations. We established the age-dependent incidence, time course, and duration of thymic enlargement in adults and demonstrated that these changes were correlated with peripheral recovery of naive CD45RA(+)CD62L(+) and signal-joint TCR rearrangement excision circle-bearing CD4(+) populations with broad TCR diversity. Furthermore, we demonstrated that renewed thymopoiesis was critical for the restoration of peripheral CD4(+) T cell populations. This recovery encompassed the recovery of normal CD4(+) T cell numbers, a low ratio of effector to central memory cells, and a broad repertoire of TCR Vbeta diversity among these memory cells. These data define the timeline and consequences of renewal of adult thymopoietic activity at levels able to quantitatively restore peripheral T cell populations. They further suggest that structural thymic regrowth serves as a basis for the regeneration of peripheral T cell populations.

Adult↗

PubMed2005

Thymic output generates a new and diverse TCR repertoire after autologous stem cell transplantation in multiple sclerosis patients.

Clinical trials have indicated that autologous hematopoietic stem cell transplantation (HSCT) can persistently suppress inflammatory disease activity in a subset of patients with severe multiple sclerosis (MS), but the mechanism has remained unclear. To understand whether the beneficial effects on the course of disease are mediated by lympho-depletive effects alone or are sustained by a regeneration of the immune repertoire, we examined the long-term immune reconstitution in patients with MS who received HSCT. After numeric recovery of leukocytes, at 2-yr follow-up there was on average a doubling of the frequency of naive CD4(+) T cells at the expense of memory T cells. Phenotypic and T cell receptor excision circle (TREC) analysis confirmed a recent thymic origin of the expanded naive T cell subset. Analysis of the T cell receptor repertoire showed the reconstitution of an overall broader clonal diversity and an extensive renewal of clonal specificities compared with pretherapy. These data are the first to demonstrate that long-term suppression of inflammatory activity in MS patients who received HSCT does not depend on persisting lymphopenia and is associated with profound qualitative immunological changes that demonstrate a de novo regeneration of the T cell compartment.

Adult↗

PubMed2005

Reconstitution of the lymphocyte compartment after lymphocyte depletion: a key issue in clinical immunology.

Loss of existing T cell populations is a significant clinical problem following cytoreductive therapies or in disease states such as HIV. Characterization of the pathways of T cell regeneration, their limitations and regulation, is central to the development of new approaches for the correction of T cell lymphopenia. Recently, there has been an increasing appreciation that subsets of T cells differ not only in requirements for homeostasis, but in the mechanisms of initial generation and later reconstitution of lost populations. In this issue, Cox et al. determine that variations in cytokine/chemokine levels may affect the biology of T cell recovery which impacts on the development of treatment strategies for lymphopenia.

Cell Proliferation↗

PubMed2005

Establishing a platform for immunotherapy: clinical outcome and study of immune reconstitution after high-dose chemotherapy with progenitor cell support in breast cancer patients.

Tumor vaccine after high-dose chemotherapy (HDC) and autologous stem cell transplantation (ASCT) aims at directing immune recovery toward tumor responses after optimizing minimal residual disease. We have characterized T-cell recovery and tumor response after a regimen devised as a platform for such immunotherapy. One hundred patients with high-risk or metastatic breast cancer received 3 to 7 cycles of paclitaxel and cyclophosphamide (overall response rate, 78%) and then HDC with melphalan and etoposide. Seventy-one patients received HDC and ASCT (no mortality at 100 days). At 24 months after transplantation, progression-free and overall survival probabilities for patients with stage IIIA, IIIB, and IV disease were 82%, 81%, and 42% and 100%, 94%, and 68%, respectively. The median progression-free and overall survivals from entry on study for stage IV patients were 15.3 and 38.1 months, respectively. CD3 + , CD8 + , and CD4 + cells were severely depleted after ASCT. Although total CD8 + T-cell numbers approached the normal range by 3 months, most of these cells were CD28 - . Naive CD45RA + CD4 + T cells approached the normal range only 18 months after ASCT and only in younger patients. The described observations provide the basis for devising a strategy for cancer vaccine administration after ASCT. Incorporating immune reconstitution enhancement after ASCT may be advantageous.

Adult↗

PubMed2005

Efficacy of reduced-intensity allogeneic stem cell transplantation in chemotherapy-refractory non-hodgkin lymphoma.

Chemotherapy sensitivity has been identified as an important prognostic factor in reduced-intensity allogeneic stem cell transplantation (RIST) for non-Hodgkin lymphoma (NHL). However, the effect of uniform salvage chemotherapy before RIST has not been studied prospectively. We examined whether the response to prospectively administered uniform salvage therapy (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and fludarabine) influenced the subsequent outcome of RIST in 28 patients with relapsed or refractory NHL. After RIST, overall survival (OS) at 36 months is 49%, whereas event-free survival (EFS) is 32%. In Cox model analyses, the response to chemotherapy was the best predictor of OS (P = .0006) and EFS (P = .0006) after RIST. Differentiating stable disease from progressive disease after salvage chemotherapy strengthened the association with survival. Among chemotherapy-sensitive patients, the median OS and EFS have not been reached. In patients with stable disease, OS and EFS at 24 months are 50% and 25%, respectively. In contrast, only 1 patient with progressive disease during salvage therapy survived longer than 12 months. These prospective data confirm the favorable prognosis for chemotherapy-sensitive NHL after RIST and suggest that chemotherapy resistance is not an absolute contraindication to RIST for NHL patients with stable disease during salvage therapy.

Adult↗

PubMed2004

Transforming growth factor-beta pathway serves as a primary tumor suppressor in CD8+ T cell tumorigenesis.

Tumorigenesis in rodents, as well as in humans, has been shown to be a multistep process, with each step reflecting an altered gene product or gene regulatory process leading to autonomy of cell growth. Initial genetic mutations are often associated with dysfunctional growth regulation, as is demonstrated in several transgenic mouse models. These changes are often followed by alterations in tumor suppressor gene function, allowing unchecked cell cycle progression and, by genomic instability, additional genetic mutations responsible for tumor metastasis. Here we show that reduced transforming growth factor-beta signaling in T lymphocytes leads to a rapid expansion of a CD8+ memory T-cell population and a subsequent transformation to leukemia/lymphoma as shown by multiple criteria, including peripheral blood cell counts histology, T-cell receptor monoclonality, and host transferability. Furthermore, spectral karyotype analysis of the tumors shows that the tumors have various chromosomal aberrations. These results suggest that reduced transforming growth factor-beta signaling acts as a primary carcinogenic event, allowing uncontrolled proliferation with consequent accumulation of genetic defects and leukemic transformation.

Animals↗

PubMed2004

Dynamic regulation of IL-7 receptor expression is required for normal thymopoiesis.

Interleukin-7 receptor (IL-7R) levels are tightly controlled during ontogeny: high on double-negative (DN) cells, absent on double-positive (DP) cells, and high once again on thymocytes undergoing positive selection. To determine if loss of IL-7-mediated survival signals in DP cells is necessary for normal antigen-specific selection, we created T-lineage-specific IL-7R alpha chain (IL-7Ralpha) transgenic (Tg) mice in which IL-7R is expressed throughout ontogeny. There was no effect of the IL-7Ralpha Tg on negative selection. Surprisingly, however, although the thymi of IL-7Ralpha Tg mice were comparable at birth, there was a decrease in thymocyte number as the mice aged. This was found to be due to competition between DN and IL-7R-expressing DP cells for endogenous IL-7, which resulted in decreased levels of Bcl-2 in DN cells, increased DN apoptosis, and decreased DN cell number. Therefore, the down-regulation of IL-7R on DP cells is an "altruistic" act required for maintaining an adequate supply of local IL-7 for DN cells.

Animals↗

PubMed2004

L-Selectin(hi) but not the L-selectin(lo) CD4+25+ T-regulatory cells are potent inhibitors of GVHD and BM graft rejection.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after bone marrow transplantation (BMT). CD4(+)CD25(+) immune regulatory T cells (Tregs), long recognized for their critical role in induction and maintenance of self-tolerance and prevention of autoimmunity, are also important in the regulation of immune responses in allogeneic bone marrow (BM) and solid organ transplantation. Published data indicate that ex vivo activated and expanded donor Tregs result in significant inhibition of lethal GVHD. This study provides a direct comparison of LSel(hi) and LSel(lo) Tregs for GVHD inhibition and for the promotion of allogeneic BM engraftment. Imaging of green fluorescent protein-positive effectors in GVHD control mice and LSel(hi) and LSel(lo) Treg-treated mice vividly illustrate the multisystemic nature of GVHD and the profound inhibition of GVHD by LSel(hi) Tregs. Data indicate that LSel(hi) Tregs interfere with the activation and expansion of GVHD effector T cells in secondary lymphoid organs early after BMT. Either donor- or host-type LSel(hi), but not LSel(lo), Tregs potently increased donor BM engraftment in sublethally irradiated mice, an event occurring independently of transforming growth factor beta signaling of host T cells. These data indicate that Treg cellular therapy warrants clinical consideration for the inhibition of GVHD and the promotion of alloengraftment.

Animals↗

PubMed2004

Flt3 ligand enhances thymic-dependent and thymic-independent immune reconstitution.

Despite recent progress in our understanding of the biology of T-cell homeostasis, clinically available therapies to substantially improve immune reconstitution in patients sustaining T-cell depletion are lacking. T cells are regenerated via a dynamic interplay between thymopoiesis and thymic-independent homeostatic peripheral expansion (HPE). Using athymic mice subjected to T-cell depletion, we observed that HPE is critically dependent on dendritic cells (DCs) for presentation of antigen, raising the possibility that the availability of DCs might be limiting in vivo for HPE to occur efficiently. Indeed, flt3 ligand (flt3L) treatment of athymic mice subjected to T-cell depletion (without DC depletion) substantially enhanced HPE and improved immune competence. Following bone marrow transplantation (BMT) in athymic hosts, both dendritic cells and T cells were profoundly depleted and flt3L therapy restored DC numbers and enhanced HPE. In addition, thymus-bearing BMT recipients treated with flt3L regenerated increased numbers of thymic-dependent progeny with increased numbers of T-cell receptor excision circle (TREC)-positive T cells, indicating increased thymopoiesis. Therefore, flt3L is a potent immunorestorative agent that enhances both thymic-dependent and thymic-independent pathways of T-cell regeneration.

Animals↗

PubMed2004

A dose effect of IL-7 on thymocyte development.

To study interleukin-7 (IL-7) in early thymocyte development, we generated mice transgenic (Tg) for the IL-7 gene under control of the lck proximal promoter. Founder line TgA, with the lowest level of IL-7 overexpression, showed enhanced alphabeta T-cell development. In contrast, in the highest overexpressing founder line, TgB, alphabeta T-cell development was disturbed with a block at the earliest intrathymic precursor stage. This was due to decreased progenitor proliferation as assessed by Ki-67 staining and in vivo bromodeoxyuridine (BrdU) incorporation. Bcl-2 was up-regulated in T-cell-committed progenitors in all Tg lines, and accounted for greater numbers of double positive (DP), CD4 single positive (SP), and CD8SP thymocytes in TgA mice where, in contrast to TgB mice, thymocyte progenitor proliferation was normal. Mixed marrow chimeras using TgB(+) and congenic mice as donors, and experiments using anti-IL-7 monoclonal antibody (MAb) in vivo, confirmed the role of IL-7 protein in the observed TgB phenotype. In conclusion, at low Tg overexpression, IL-7 enhanced alphabeta T-cell development by increasing thymocyte progenitor survival, while at high overexpression IL-7 reduces their proliferation, inducing a dramatic block in DP production. These results show for the first time in vivo a dose effect of IL-7 on alphabeta T-cell development and have implications for IL-7 in the clinical setting.

Animals↗

PubMed2004

Exogenous IL-7 increases recent thymic emigrants in peripheral lymphoid tissue without enhanced thymic function.

Interleukin 7 (IL-7) is critical in maintaining thymic-dependent and thymic-independent pathways of T-cell homeostasis. T-cell receptor (TCR) rearrangement excision circles (TRECs) have been used as markers for recent thymic emigrants (RTEs) in assessing human thymic function. To study the thymic and peripheral effects of IL-7 on RTEs, we measured TREC content and peripheral naive T-cell subsets and turnover in IL-7-treated mice. Short-term administration of IL-7 into thymus-intact mice resulted in increased total TREC numbers, consistent with RTE accumulation. Decreases in TREC frequency were attributable to dilution secondary to increased cell turnover. Significantly, IL-7 administration into thymectomized mice resulted in patterns of decreased TREC frequency and increased total TREC number similar to those in IL-7-treated thymus-intact mice. Distinct patterns of naive cell and RTE distribution among peripheral immune organs and altered expression of CD11a were observed following IL-7 treatment in thymus-intact and thymectomized mice. These results demonstrate (1) that total TREC number and not TREC frequency accurately reflects quantitative changes in RTEs; (2) that short-term IL-7 administration results in preferential accumulations of RTEs among peripheral immune organs, accounting for the increase in TRECs in the total peripheral lymphoid pool; and (3) no evidence for regulation of thymic function by short-term IL-7 administration.

Animals↗