Tumor cell budding and laminin-5 expression in colorectal carcinoma can be modulated by the tissue micro-environment.

Expression of laminin-5 alpha3, beta3 and gamma2 protein subunits was investigated in colorectal adenocarcinomas using immunostaining and confocal microscopy. The laminin-5 heterotrimer was found in basement membranes and as extracellular deposits in tumor stroma. In contrast to the alpha3 subunit, which was under-expressed, the gamma2 and beta3 subunits were detected in the cytoplasm of carcinoma cells dissociating (budding) from neoplastic tubules, suggestive of focal alterations in laminin-5 assembly and secretion. Laminin-5 gamma2 or beta3 subunit-reactive budding carcinoma cells expressed cytokeratins but not vimentin; they did not proliferate and were not apoptotic. Furthermore, expression of laminin-5 gamma2 and beta3 subunits in budding cells was associated with focal under-expression of the E-cadherin-beta-catenin complex. Results from xenograft experiments showed that budding activity in colorectal adenocarcinomas could be suppressed when these tumors grew at ectopic s.c. sites in nude mice. In vitro, cultured colon carcinoma cells, but not adenoma-derived tumor cells, shared the laminin-5 phenotype expressed by carcinoma cells in vivo. Using colon carcinoma cell lines implanted orthotopically and invading the cecum of nude mice, the laminin-5-associated budding was restored, indicating that this phenotype is not only determined by tumor cell properties but also dependent on the tissue micro-environment. Our results indicate that both laminin-5 alpha3 subunit expression and cell-cell cohesiveness are altered in budding carcinoma cells, which we consider to be actively invading. We propose that the local tissue micro-environment contributes to these events.

Humoral and cellular rejection after combined liver-kidney transplantation in low immunologic risk recipients.

Combined liver-kidney transplantation is considered a low risk for immunologic complication. We report an unusual case of identical ABO liver-kidney recipient without preformed anti-human leukocyte antigen (HLA) antibodies, transplanted across a T- and B-cell-negative cross-match and complicated by early acute humoral and cellular rejection, first in the liver then in the kidney. While analyzing the immunologic complications in our cohort of 12 low-risk combined liver-kidney recipients, only one recipient experienced a rejection episode without detection of anti-HLA antibody over time. Although humoral or cellular rejection is rare after combined kidney-liver transplantation, our data suggest that even in low-risk recipients, the liver does not always systematically protect the kidney from acute rejection. Indeed, the detection of C4d in the liver should be carefully followed after combined liver-kidney transplantation.

Flow-microfluorometric monitoring of oligoclonal CD8+ T cell responses to an immunodominant Moloney leukemia virus-encoded epitope in vivo.

The TCR repertoire of CD8+ T cells specific for Moloney murine leukemia virus (M-MuLV)-associated Ags has been investigated in vitro and in vivo. Analysis of a large panel of established CD8+ CTL clones specific for M-MuLV indicated an overwhelming bias for V beta4 in BALB/c mice and for V beta5.2 in C57BL/6 mice. These V beta biases were already detectable in mixed lymphocyte:tumor cell cultures established from virus-immune spleen cells. Furthermore, direct ex vivo analysis of PBL from BALB/c or C57BL/6 mice immunized with syngeneic M-MuLV-infected tumor cells revealed a dramatic increase in CD8+ cells expressing V beta4 or V beta5.2, respectively. M-MuLV-specific CD8+ cells with an activated (CD62L-) phenotype persisted in blood of immunized mice for at least 2 mo, and exhibited decreased TCR and CD8 levels compared with their naive counterparts. In C57BL/6 mice, most M-MuLV-specific CD8+ CTL clones and immune PBL coexpressed V alpha3.2 in association with V beta5.2. Moreover, these V beta5.2+ V alpha3.2+ cells were shown to recognize the recently described H-2Db-restricted epitope (CCLCLTVFL) encoded in the leader sequence of the M-MuLV gag polyprotein. Collectively, our data demonstrate a highly restricted TCR repertoire in the CD8+ T cell response to M-MuLV-associated Ags in vivo, and suggest the potential utility of flow-microfluorometric analysis of V beta and V alpha expression in the diagnosis and monitoring of viral infections.

Clinical consequences of sensitisation to minor histocompatibility antigens before allogeneic bone marrow transplantation.

To study sensitisation to minor histocompatibility antigens (mHag) before and after BMT, we measured antidonor CTL activity in five patients who had rejected their graft, and in a control group of 10 leukemic patients who engrafted without complications. All patients were transplanted with marrow from an HLA-identical sibling. Fourteen patients were conditioned with cyclophosphamide (120 mg/kg) and TBI (1350 cGy) and received a T cell-depleted graft, while one patient with aplastic anaemia received cyclophosphamide alone and unmanipulated marrow. Before transplantation, anti-donor CTL activity was detected in two of the 15 patients. These patients rejected their grafts at days 21 and 58, respectively. In the other three patients who rejected their grafts at days 41, 60 and 250, CTL activity was found only after transplantation. In contrast, no anti-donor CTLs could be detected at any time in the 10 patients who engrafted permanently. We have identified some of the mHags recognised during graft rejection by cloning and subsequent specificity analysis of the recipient CTLs. In the patient who rejected at day 41 without detectable immunisation before BMT, the response was directed against HA-1, a minor antigen known to play a role in GVHD. In the other combinations, a significant part of the CTL activity was directed against the male antigen H-Y. In the patient who rejected the marrow of her HLA-identical brother at day 250, two clones recognised H-Y, while five others recognised at least three distinct autosomal mHags. This patient had an HLA-identical sister who expressed only one autosomal mHag that had been recognised by one single T cell clone. After re-transplantation with the marrow of this second donor, the CTL activity could no longer be detected and the patient engrafted without further complications.

Engineering tolerance into transplanted beta cell lines.

In this paper we explore the possibility of improving, by genetic engineering, the resistance of insulin-secreting cells to the metabolic and inflammatory stresses that are anticipated to limit their function and survival when encapsulated and transplanted in a type 1 diabetic environment. We show that transfer of the Bcl-2 antiapoptotic gene, and of genes specifically interfering with cytokine intracellular signaling pathways, greatly improves resistance of the cells to metabolic limitations and inflammatory stresses.

Differential role of naïve and memory CD4 T-cell subsets in primary alloresponses.

The T cell response to major histocompatibility complex (MHC) alloantigens occurs via two main pathways. The direct pathway involves the recognition of intact allogeneic MHC:peptide complexes on donor cells and provokes uniquely high frequencies of responsive T cells. The indirect response results from alloantigens being processed like any other protein antigen and presented as peptide by autologous antigen-presenting cells. The frequencies of T cells with indirect allospecificity are orders of magnitude lower and comparable to other peptide-specific responses. In this study, we explored the contributions of naïve and memory CD4(+) T cells to these two pathways. Using an adoptive transfer and skin transplantation model we found that naive and memory CD4(+) T cells, both naturally occurring and induced by sensitization with multiple third-party alloantigens, contributed equally to graft rejection when only the direct pathway was operative. In contrast, the indirect response was predominantly mediated by the naïve subset. Elimination of regulatory CD4(+)CD25(+) T cells enabled memory cells to reject grafts through the indirect pathway, but at a much slower tempo than for naïve cells. These findings have implications for better targeting of immunosuppression to inhibit immediate and later forms of alloimmunity.

Second primary squamous cell carcinoma arising in cutaneous flap reconstructions of two head and neck cancer patients.

Early complications of myocutaneous flap transfers following surgical eradication of head and neck tumors have been extensively described. However, knowledge concerning long-term complications of these techniques remains limited. We report the cases of two patients with a prior history of squamous cell carcinoma of the head and neck (HNSCC), who developed a second primary SCC on the cutaneous surface of their flaps, years after reconstruction. Interestingly, it seems that the well-known risk of a second primary SCC in patients with previous head and neck carcinoma also applies to foreign tissues implanted within the area at risk. Given the important expansion of these interventions, this type of complication may become more frequent in the future. Therefore, long-term follow-up of patients previously treated for HNSCC not only requires careful evaluation of the normal mucosa of the upper aero-digestive tract, but also of the cutaneous surface of the flap used for reconstruction.

Low levels of human leukocyte antigen donor-specific antibodies detected by solid phase assay before transplantation are frequently clinically irrelevant.

Since new technologies based on solid phase assays (SPA) have been routinely incorporated in the transplant immunology laboratory, the presence of pretransplantation donor-specific antibodies (DSA) against human leukocyte antigen (HLA) molecules has generally been considered as a risk factor for acute rejection (AR) and, in particular, for acute humoral rejection (AHR). We retrospectively studied 113 kidney transplant recipients who had negative prospective T-cell and B-cell complement-dependent cytotoxicity (CDC) crossmatches at the time of transplant. Pretransplantation sera were screened for the presence of circulating anti-HLA antibody and DSA by using highly sensitive and HLA-specific Luminex assay, and the results were correlated with AR and AHR posttransplantation. We found that approximately half of our patient population (55/113, 48.7%) had circulating anti-HLA antibody pretransplantation. Of 113 patients, 11 (9.7%) had HLA-DSA. Of 11 rejection episodes post-transplant, only two patients had pretransplantation DSA, of whom one had a severe AHR (C4d positive). One-year allograft survival was similar between the pretransplantation DSA-positive and -negative groups. Number, class, and intensity of pretransplantation DSA, as well as presensitizing events, could not predict AR. We conclude that, based on the presence of pretransplantation DSA, post-transplantation acute rejections episodes could not have been predicted. The only AHR episode occurred in a recipient with pretransplantation DSA. More work should be performed to better delineate the precise clinical significance of detecting low titers of DSA before transplantation.

Coexpression of the T-cell receptor constant alpha domain triggers tumor reactivity of single-chain TCR-transduced human T cells.

Transfer of tumor antigen-specific T-cell receptors (TCRs) into human T cells aims at redirecting their cytotoxicity toward tumors. Efficacy and safety may be affected by pairing of natural and introduced TCRalpha/beta chains potentially leading to autoimmunity. We hypothesized that a novel single-chain (sc)TCR framework relying on the coexpression of the TCRalpha constant alpha (Calpha) domain would prevent undesired pairing while preserving structural and functional similarity to a fully assembled double-chain (dc)TCR/CD3 complex. We confirmed this hypothesis for a murine p53-specific scTCR. Substantial effector function was observed only in the presence of a murine Calpha domain preceded by a TCRalpha signal peptide for shuttling to the cell membrane. The generalization to a human gp100-specific TCR required the murinization of both C domains. Structural and functional T-cell avidities of an accessory disulfide-linked scTCR gp100/Calpha were higher than those of a dcTCR. Antigen-dependent phosphorylation of the proximal effector zeta-chain-associated protein kinase 70 at tyrosine 319 was not impaired, reflecting its molecular integrity in signaling. In melanoma-engrafted nonobese diabetic/severe combined immunodeficient mice, adoptive transfer of scTCR gp100/Calpha transduced T cells conferred superior delay in tumor growth among primary and long-term secondary tumor challenges. We conclude that the novel scTCR constitutes a reliable means to immunotherapeutically target hematologic malignancies.

Schwann cell strip for peripheral nerve repair.

Many strategies have been investigated to provide an ideal substitute to treat a nerve gap injury. Initially, silicone conduits were used and more recently conduits fabricated from natural materials such as poly-3-hydroxybutyrate (PHB) showed good results but still have their limitations. Surgically, a new concept optimising harvested autologous nerve graft has been introduced as the single fascicle method. It has been shown that a single fascicle repair of nerve grafting is successful. We investigated a new approach using a PHB strip seeded with Schwann cells to mimic a small nerve fascicle. Schwann cells were attached to the PHB strip using diluted fibrin glue and used to bridge a 10-mm sciatic nerve gap in rats. Comparison was made with a group using conventional PHB conduit tubes filled with Schwann cells and fibrin glue. After 2 weeks, the nerve samples were harvested and investigated for axonal and Schwann cell markers. PGP9.5 immunohistochemistry showed a superior nerve regeneration distance in the PHB strip group versus the PHB tube group (> 10 mm, crossed versus 3.17+/- 0.32 mm respectively, P<0.05) as well as superior Schwann cell intrusion (S100 staining) from proximal (> 10 mm, crossed versus 3.40+/- 0.36 mm, P<0.01) and distal (> 10 mm, crossed versus 2.91+/- 0.31 mm, P<0.001) ends. These findings suggest a significant advantage of a strip in rapidly connecting a nerve gap lesion and imply that single fascicle nerve grafting is advantageous for nerve repair in rats.

LIGHT/HVEM/LTβR interaction as a target for the modulation of the allogeneic immune response in transplantation.

The exchange of information during interactions of T cells with dendritic cells, B cells or other T cells regulates the course of T, B and DC-cell activation and their differentiation into effector cells. The tumor necrosis factor superfamily member LIGHT (homologous to lymphotoxin, exhibits inducible expression and competes with HSV glycoprotein D for binding to herpesvirus entry mediator, a receptor expressed on T lymphocytes) is transiently expressed upon T cell activation and modulates CD8 T cell-mediated alloreactive responses upon herpes virus entry mediator (HVEM) and lymphotoxin β receptor (LTβR) engagement. LIGHT-deficient mice, or WT mice treated with LIGHT-targeting decoy receptors HVEM-Ig, LTβR-Ig or sDcR3-Ig, exhibit prolonged graft survival compared to untreated controls, suggesting that LIGHT modulates the course and severity of graft rejection. Therefore, targeting the interaction of LIGHT with HVEM and/or LTβR using recombinant soluble decoy receptors or monoclonal antibodies represent an innovative therapeutic strategy for the prevention and treatment of allograft rejection and for the promotion of donor-specific tolerance.

The early IL-4 response to Leishmania major and the resulting Th2 cell maturation steering progressive disease in BALB/c mice are subject to the control of regulatory CD4+CD25+ T cells.

Susceptibility and development of Th2 cells in BALB/c mice infected with Leishmania major result from early IL-4 production by Vbeta4Valpha8 CD4+ T cells in response to the Leishmania homolog of mammalian RACK1 Ag. A role for CD4+CD25+ regulatory T cells in the control of this early IL-4 production was investigated by depleting in vivo this regulatory T cell population. Depletion induced an increase in the early burst of IL-4 mRNA in the draining lymph nodes of BALB/c mice, and exacerbated the course of disease with higher levels of IL-4 mRNA and protein in their lymph nodes. We further showed that transfer of 10(7) BALB/c spleen cells that were depleted of CD4+CD25+ regulatory T cells rendered SCID mice susceptible to infection and allowed Th2 differentiation while SCID mice reconstituted with 10(7) control BALB/c spleen cells were resistant to infection with L. major and developed a Th1 response. Treatment with a mAb against IL-4 upon infection with L. major in SCID mice reconstituted with CD25-depleted spleen cells prevented the development of Th2 polarization and rendered them resistant to infection. These results demonstrate that CD4+CD25+ regulatory T cells play a role in regulating the early IL-4 mRNA and the subsequent development of a Th2 response in this model of infection.

Bortezomib(Velcade®)-Thalidomide-Dexamethasone (VTD) Is Superior to Thalidomide-Dexamethasone (TD) In Patients with Multiple Myeloma (MM) Progressing or Relapsing After Autologous Transplantation

Introduction: The Thalidomide-Dexamethasone (TD) regimen has provided encouraging results in relapsed MM. To improve results, bortezomib (Velcade) has been added to the combination in previous phase II studies, the so called VTD regimen. In January 2006, the European Group for Blood and Marrow Transplantation (EBMT) and the Intergroupe Francophone du Myélome (IFM) initiated a prospective, randomized, parallel-group, open-label phase III, multicenter study, comparing VTD (arm A) with TD (arm B) for MM patients progressing or relapsing after autologous transplantation. Patients and Methods: Inclusion criteria: patients in first progression or relapse after at least one autologous transplantation, including those who had received bortezomib or thalidomide before transplant. Exclusion criteria: subjects with neuropathy above grade 1 or non secretory MM. Primary study end point was time to progression (TTP). Secondary end points included safety, response rate, progression-free survival (PFS) and overall survival (OS). Treatment was scheduled as follows: bortezomib 1.3 mg/m2 was given as an i.v bolus on Days 1, 4, 8 and 11 followed by a 10-Day rest period (days 12 to 21) for 8 cycles (6 months) and then on Days 1, 8, 15, 22 followed by a 20-Day rest period (days 23 to 42) for 4 cycles (6 months). In both arms, thalidomide was scheduled at 200 mg/Day orally for one year and dexamethasone 40 mg/Day orally four days every three weeks for one year. Patients reaching remission could proceed to a new stem cell harvest. However, transplantation, either autologous or allogeneic, could only be performed in patients who completed the planned one year treatment period. Response was assessed by EBMT criteria, with additional category of near complete remission (nCR). Adverse events were graded by the NCI-CTCAE, Version 3.0.The trial was based on a group sequential design, with 4 planned interim analyses and one final analysis that allowed stopping for efficacy as well as futility. The overall alpha and power were set equal to 0.025 and 0.90 respectively. The test for decision making was based on the comparison in terms of the ratio of the cause-specific hazards of relapse/progression, estimated in a Cox model stratified on the number of previous autologous transplantations. Relapse/progression cumulative incidence was estimated using the proper nonparametric estimator, the comparison was done by the Gray test. PFS and OS probabilities were estimated by the Kaplan-Meier curves, the comparison was performed by the Log-Rank test. An interim safety analysis was performed when the first hundred patients had been included. The safety committee recommended to continue the trial. Results: As of 1st July 2010, 269 patients had been enrolled in the study, 139 in France (IFM 2005-04 study), 21 in Italy, 38 in Germany, 19 in Switzerland (a SAKK study), 23 in Belgium, 8 in Austria, 8 in the Czech republic, 11 in Hungary, 1 in the UK and 1 in Israel. One hundred and sixty nine patients were males and 100 females; the median age was 61 yrs (range 29-76). One hundred and thirty six patients were randomized to receive VTD and 133 to receive TD. The current analysis is based on 246 patients (124 in arm A, 122 in arm B) included in the second interim analysis, carried out when 134 events were observed. Following this analysis, the trial was stopped because of significant superiority of VTD over TD. The remaining patients were too premature to contribute to the analysis. The number of previous autologous transplants was one in 63 vs 60 and two or more in 61 vs 62 patients in arm A vs B respectively. The median follow-up was 25 months. The median TTP was 20 months vs 15 months respectively in arm A and B, with cumulative incidence of relapse/progression at 2 years equal to 52% (95% CI: 42%-64%) vs 70% (95% CI: 61%-81%) (p=0.0004, Gray test). The same superiority of arm A was also observed when stratifying on the number of previous autologous transplantations. At 2 years, PFS was 39% (95% CI: 30%-51%) vs 23% (95% CI: 16%-34%) (A vs B, p=0.0006, Log-Rank test). OS in the first two years was comparable in the two groups. Conclusion: VTD resulted in significantly longer TTP and PFS in patients relapsing after ASCT. Analysis of response and safety data are on going and results will be presented at the meeting.

Cutting edge: cell autonomous rather than environmental factors control bacterial superantigen-induced T cell anergy in vivo.

Anergic T cells display a marked decrease in their ability to produce IL-2 and to proliferate in the presence of an appropriate antigenic signal. Two nonmutually exclusive classes of models have been proposed to explain the persistence of T cell anergy in vivo. While some reports indicate that anergic T cells have intrinsic defects in signaling pathways or transcriptional activities, other studies suggest that anergy is maintained by environmental "suppressor" factors such as cytokines or Abs. To distinguish between these conflicting hypotheses, we employed the well-characterized bacterial superantigen model system to evaluate in vivo the ability of a trace population of adoptively transferred naive or anergized T cells to proliferate in a naive vs anergic environment upon subsequent challenge. Our data clearly demonstrate that bacterial superantigen-induced T cell anergy is cell autonomous and independent of environmental factors.

Cell-mediated immunity to predict cytomegalovirus disease in high-risk solid organ transplant recipients.

Late-onset cytomegalovirus (CMV) disease commonly occurs after discontinuation of antiviral prophylaxis. We determined the utility of testing CD8+ T-cell response against CMV as a predictor of late-onset CMV disease after a standard course of antiviral prophylaxis. Transplant patients at high-risk for CMV disease were enrolled. CD8+ T-cell-mediated immunity (CMI) was tested using the QuantiFERON-CMV assay at baseline, 1, 2 and 3 months posttransplant by measurement of interferon-gamma response to whole blood stimulation with a 21-peptide pool. The primary outcome was the ability of CMI testing to predict CMV disease in the first 6 months posttransplant. There were 108 evaluable patients (D+/R+ n = 39; D-/R+ n = 34; D+/R- n = 35) of whom 18 (16.7%) developed symptomatic CMV disease. At the end of prophylaxis, CMI was detectable in 38/108 (35.2%) patients (cutoff 0.1 IU/mL interferon-gamma). CMV disease occurred in 2/38 (5.3%) patients with a detectable interferon-gamma response versus 16/70 (22.9%) patients with a negative response; p = 0.038. In the subgroup of D+/R- patients, CMV disease occurred in 1/10 (10.0%) patients with a detectable interferon-gamma response (cutoff 0.1 IU/mL) versus 10/25 (40.0%) patients with a negative CMI, p = 0.12. Monitoring of CMI may be useful for predicting late-onset CMV disease.