Lymphopenia combined with low TCR diversity (divpenia) predicts poor overall survival in metastatic breast cancer patients

Lymphopenia (< 1Giga/L) detected before initiation of chemotherapy is a predictive factor for death in metastatic solid tumors. Combinatorial T cell repertoire (TCR) diversity was investigated and tested either alone or in combination with lymphopenia as a prognostic factor at diagnosis for overall survival (OS) in metastatic breast cancer (MBC) patients. The combinatorial TCR diversity was measured by semi quantitative multi-N-plex PCR on blood samples before the initiation of the first line chemotherapy in a development (n = 66) and validation (n = 67) MBC patient cohorts. A prognostic score, combining lymphocyte count and TCR diversity was evaluated. Univariate and multivariate analyses of prognostic factors for OS were performed in both cohorts. Lymphopenia and severe restriction of TCR diversity called “divpenia” (diversity ≤ 33%) were independently associated with shorter OS. Lympho-divpenia combining lymphopenia and severe divpenia accurately identified patients with poor OS in both cohorts (7.6 and 10.6 vs 24.5 and 22.9 mo). In multivariate analysis including other prognostic clinical factors, lympho-divpenia was found to be an independent prognostic factor in the pooled cohort (p = 0.005) along with lack of HER2 and hormonal receptors expression (p = 0.011) and anemia (p = 0.009). Lympho-divpenia is a novel prognostic factor that will be used to improve quality of MBC patients’ medical care.

Peripheral Blood TCR Repertoire Profiling May Facilitate Patient Stratification for Immunotherapy against Melanoma

Many metastatic melanoma patients experience durable responses to anti-PD1 and/or anti-CTLA4; however, a significant proportion (over 50%) do not benefit from the therapies. In this study, we sought to assess pretreatment liquid biopsies for biomarkers that may correlate with response to checkpoint blockade. We measured the combinatorial diversity evenness of the T-cell receptor (TCR) repertoire (the DE₅₀, with low values corresponding to more clonality and lack of TCR diversity) in pretreatment peripheral blood mononuclear cells from melanoma patients treated with anti-CTLA4 (n = 42) or anti-PD1 (n = 38) using a multi-N-plex PCR assay on genomic DNA (gDNA). A receiver operating characteristic curve determined the optimal threshold for a dichotomized analysis according to objective responses as defined by RECIST1.1. Correlations between treatment outcome, clinical variables, and DE₅₀ were assessed in multivariate regression models and confirmed with Fisher exact tests. In samples obtained prior to treatment initiation, we showed that low DE₅₀ values were predictive of a longer progression-free survival and good responses to PD-1 blockade, but, on the other hand, predicted a poor response to CTLA4 inhibition. Multivariate logistic regression models identified DE₅₀ as the only independent predictive factor for response to anti-CTLA4 therapy (P = 0.03) and anti-PD1 therapy (P = 0.001). Fisher exact tests confirmed the association of low DE₅₀ with response in the anti-CTLA4 (P = 0.041) and the anti-PD1 cohort (P = 0.0016). Thus, the evaluation of basal TCR repertoire diversity in peripheral blood, using a PCR-based method, could help predict responses to anti-PD1 and anti-CTLA4 therapies.

Peripheral T cell receptor diversity is associated with clinical outcomes following ipilimumab treatment in metastatic melanoma

Background

Ipilimumab improves overall survival in a subset of patients with metastatic melanoma. Peripheral blood T cell receptor (TCR) repertoire diversity has been associated with favorable outcomes in patients with cancer, but its relevance as a biomarker for ipilimumab outcomes remains unknown.

Findings

In this pilot study, we analyzed the pre-treatment peripheral blood TCR repertoire in 12 patients with metastatic melanoma who received ipilimumab at 3 mg/kg (clinical benefit, n = 4; no clinical benefit, n = 8). TCR diversity was evaluated using a polymerase chain reaction assay which measures TCR combinatorial diversity between V and J genes from genomic DNA. TCR repertoire diversity was studied through richness (observed V-J rearrangements) and evenness (similarity between the frequencies of specific V-J rearrangements). The Wilcoxon rank sum test was used to compare patients with clinical benefit and those without. Association with benefit in a dichotomized analysis was assessed through a Fisher’s exact test. Overall survival was studied through log-rank analysis.

There was a significant difference in richness (p = 0.033) and evenness (p = 0.028) between patients with and without clinical benefit. Dichotomized analysis showed that none of the patients with low richness (n = 0/5, p = 0.081) nor low evenness (n = 0/7, p = 0.01) achieved clinical benefit. There were no significant differences in overall survival.

Conclusions

In this small group of patients, baseline TCR diversity in the peripheral blood was associated with clinical outcomes. Further investigation is ongoing in larger cohorts of patients to explore these preliminary findings and determine whether TCR diversity can be used as a predictive biomarker in cancer immunotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-015-0070-4) contains supplementary material, which is available to authorized users.

Clonal restriction and predominance of regulatory T cells in coronary thrombi of patients with acute coronary syndromes

AIMS

Regulatory T cells (Treg) exert anti-inflammatory and atheroprotective effects in experimental atherosclerosis. Treg can be induced against specific antigens using immunization strategies associated with clonal restriction. No data exist on Treg in combination with clonal restriction of T cells in patients with acute coronary syndromes (ACS).

METHODS AND RESULTS

Among T cell subsets characterized by flow cytometry, Treg (CD4(+) CD25(+) CD127(low)) were twice as frequent in coronary thrombi compared with peripheral blood. Treg prevailed among T cell subsets identified in coronary thrombi. To evaluate clonal restriction, genomic DNA was extracted from coronary thrombi and peripheral blood in order to evaluate T cell receptor (TCR) β chain diversity by means of Multi-N-plex PCR using a primer specific for all TCR β V gene segments and another primer specific for TCR β J gene segments. T cell receptor diversity was reduced in thrombi compared with peripheral blood (intra-individual comparisons in 16 patients) with 8 gene rearrangements in the TCR common in at least 6 out of 16 analysed coronary thrombi. Compared with age-matched healthy controls (n = 16), TCR diversity was also reduced in peripheral blood of patients with ACS; these findings were independent of peripheral T cell numbers.

CONCLUSION

We provide novel evidence for a perturbed T cell compartment characterized by clonal restriction in peripheral blood and coronary thrombi from patients with ACS. Our findings warrant further studies on Treg as novel therapeutic targets aimed at enhancing this anti-inflammatory component of adaptive immunity in human atherothrombosis.

Abstract CT333: Elypse-7: A randomized, placebo-controlled, Phase 2a evaluating the impact of IL-7 immunotherapy on CD4 count, risks of severe haematological toxicity and tumor progression in metastatic breast cancer patients

Background: Total and CD4 lymphopenia is observed in 25% of advanced cancers patients and is a predictive factor of chemotherapy (CT)-induced death, febrile neutropenia, thrombocytopenia, anemia, as well as an independent prognostic factor for survival and tumor progression. CYT107 is a glycosylated recombinant human IL-7 (CYTHERIS, France) emerging as a promising immuno-restorative agent well tolerated in Phase 1 trials. To date, it is unknown whether IL-7 can correct lymphopenia during CT and whether this could translate into clinical benefit in advanced cancer patients.

Methods: A placebo-controlled, monocentric, Phase 2a (NCT01368107) was conducted in lymphopenic metastatic breast cancer (MBC) patients to be treated by capecitabine (2500mg/m2/d, pers os, 21-day cycle from D21 after randomization). Using a 2x2 factorial design, patients were randomly allocated to 4 arms to receive 1) before the 1st cycle of CT : r-hIL-7 (CYT107:10µg/kg, subcutaneously, weekly at D0, D7, D14, groups 2 & 4) or placebo (groups 1 & 3), then 2) during the 3rd cycle of CT: r-hIL-7 (weekly at D57, D64, D71, groups 3 & 4) or placebo (groups 1 & 2). The primary endpoint, CD4 count evolution, was evaluated before (D0 to D21) and during CT (D57 to D78). Secondary endpoints include risks of severe hematological AE, safety and progression free survival (PFS). An ancillary study has evaluated the quantitative and functional changes in circulating immune cells (see abstract Ménétrier-Caux).

Results: From Nov. 2011 to Jun. 2013, 20 patients (median age [range]: 60 [39-76 y.]; median CD4 count on D0: 242 [22-522 cells/µL]) with MBC (mainly with bone and liver metastasis) were enrolled. Before CT (n=20), r-hIL-7 treatment induced a significant increase of CD4 count (median relative evolution: +148.1% [41.8-763.9 cells/µL] in r-hIL-7 groups vs +9.9% [-50.3-102.2 cells/µL] in placebo [Wilcoxon, p=0.002]). During CT (n=11), r-hIL-7 treatment also increased CD4 count (+58.6%[-15.2-281.5 cells/µL] in r-hIL-7 groups vs -2.4% [-27.6-112.5 cells/µL] in placebo [p=0.121]). Overall, r-hIL-7 was well tolerated with reactions related to injection as the main specific AE, no binding or neutralizing antibodies, and no r-hIL-7-related ≥ Grade 3 AE except 1 fatal SAE for which one a relationship to r-hIL-7 cannot be ruled out. Interestingly, r-hIL-7 treatment during CT reduced the incidence of Grade 3 hematological AE compared to placebo (0 vs 5 events, respectively). PFS data will be available by Feb. 2014.

Conclusion: In this exploratory trial, r-hIL-7 treatment was safe at biologically active dose, able to correct CD4 lymphopenia and associated with lower incidence of severe hematological toxicity during CT. These early results are encouraging and warrant further investigations of IL-7 clinical applications in the oncology field.

Citation Format: Ray-Coquard Isabelle, Olivier Tredan, Gwenaele Garin, Christine Ménétrier-Caux, Sylvie Chabaud, Thomas Bachelot, Claire Cropet, Pierre-Etienne Heudel, Paul Rebattu, Patricia Dupont, Estelle Verronese, Anne-claire Cadore, Valérie Fouillat, Olfa Derbel, Nathalie Bonnin, Thérèse Croughs, Michel Morre, Nicolas Pasqual, Manuari Manuel, Gilles Clapisson, Christophe Caux, David Pérol, Jean-Yves Blay. Elypse-7: A randomized, placebo-controlled, Phase 2a evaluating the impact of IL-7 immunotherapy on CD4 count, risks of severe haematological toxicity and tumor progression in metastatic breast cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT333. doi:10.1158/1538-7445.AM2014-CT333

Abstract 2574: Interleukin-7 (CYT107) treatment in lymphopenic 1st line metastatic breast carcinoma patients treated with chemotherapy regimen (Capecitabine) favors the restoration of T-cell subsets number

Introduction: We previously showed that T (&lt;1000/µl) or CD4 (&lt;450/µl) T cell lymphopenia detected before chemotherapy initiation predicts early death for metastatic breast cancer (MBC) patients. ELYPSE-7, a placebo-controlled clinical trial aimed to evaluate impact of CYT107 treatment (before or during chemotherapy) on CD4 T cell count (see Ray-Coquard abstract). Our ancillary study reports in-depth quantitative and functional changes in circulating immune populations.

Methods: Lymphocytes, NK, monocytes and DC subpopulations quantification and functional competence after reactivation (PMA/ionomycin, TLR7/8-Ligand) were assessed by multiparametric flow-cytometry (surface markers/ intracytoplasmic cytokines) on fresh whole blood (D0, D21, D57, D78, EOS). Impact of CYT107 treatment before (D0-D21) or during (D57-D78) chemotherapy on immune parameters was assessed.

Results: At inclusion, 20 patients presented strong quantitative alteration of all lymphocytes subsets compared to a healthy donor women cohort (n=30). Inflammatory monocytes (infl-Mo) and DC subsets were quantitatively reduced. CD4 CD45R0+ T (IFNγ/IL-2), Tγδ cells and NK (IFNγ) cytokine productions were altered independently of quantitative alterations highlighting the importance to assess both. Pre-chemotherapy, CYT107 significantly increased CD3 T cell absolute number (median relative evolution: CYT107+128.5%[39;606cells/µL] vs placebo +1.6%[-34;85cells/µL], p=0.002) involving both CD4 (p=0.002) or CD8 (p=0.006) T cells and naïve (CD4:p=0.005 and CD8:p&lt;10-3) and memory subsets (CD4:p&lt;10-3 and CD8:p=0.008). CYT107 pre-chemotherapy induced a Treg number increase (p=0.017) remaining however in the normal range. In contrast, B cells, infl-Mo, DC and NK absolute numbers were not significantly modified. During chemotherapy (D57-D78, n=11), T cell absolute number increases in CYT107 group vs placebo (median relative evolution: CYT107 +61.5%[-11.1;229.7cells/µL] vs placebo -0.5%[-30.7;73.5cells/µL], p=0.083), CD4 and CD8 subsets being affected and in particular CD8 naive(median relative evolution: CYT107 +75.8%[39.0;314.6cells/µL] vs placebo -0.6%[-18.7;48.4cells/µL], p=0.022) and memory subsets (median relative evolution: CYT107 +72.1%[-21.9;282.7cells/µL] vs placebo -8.6%[-43.3;32.8cells/µL], p=0.055). Of importance, no significant modulation of immune cells functional competence was observed upon CYT107 treatment.

Conclusion: CYT107 administered before chemotherapy, increases all T cell subsets absolute number but no other compartments without affecting their functional responses. Interestingly, during chemotherapy, CYT107 induces an increase of CD8 memory cells, known to play a role in long lasting defense against tumors.

Citation Format: Christine Menetrier-Caux, Isabelle Ray-Coquard, Claire Cropet, Estelle Verronese, Thomas Bachelot, Olivier Tredan, Gwenaelle Garin, Pierre Heudel, Axelle N'Kodia, Ana Delgado, Christine Bardin-Dit-Courageot, Chantal Rigal, Gilles Clapisson, Sylvie Chabaud, David Perol, Paul Rebattu, Thérèse Croughs, Nicolas Pasqual, Manuarii Manuel, Michel Morre, Jean-Yves Blay, Christophe Caux. Interleukin-7 (CYT107) treatment in lymphopenic 1st line metastatic breast carcinoma patients treated with chemotherapy regimen (Capecitabine) favors the restoration of T-cell subsets number. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2574. doi:10.1158/1538-7445.AM2014-2574

Patients with metastatic breast cancer leading to CD4+ T cell lymphopaenia have poor outcome

BACKGROUND

Low lymphocyte count is a prognostic factor in cancer patients including metastatic breast cancer patients (MBC) but the relative role of each lymphocyte subtype is unclear in MBC.

METHODS

The impact of lymphocyte subsets was analysed in two prospective MBC patients' cohorts. Cohort A patients (n=103) were included before the first line of chemotherapy and cohort B patients (n=101) were included after at least one line of chemotherapy. Extensive phenotypic analyses were performed on fresh whole blood. Plasma cytokines levels were measured using commercially available Luminex-based multiplex kits. Prognostic value of lymphocyte subsets and circulating cytokines was analysed.

RESULTS

In both cohorts, severe lymphopaenia (<0.7 Giga/L) correlated with poor overall survival (OS) (median OS: 6.6 months versus 21.7 months in cohort A and 4.5 versus 9 months in cohort B). CD8(+), CD19(+) and CD56(+) T cell counts had no significant prognostic value for OS. After stratification (≤0.2, [0.20-0.45], >0.45 Giga/L), CD4 lymphopaenia appeared to be correlated with poor OS in both cohorts. Furthermore, severe CD4(+) lymphopaenia (≤0.2 Giga/L) was strongly correlated with poor OS in both cohorts (1.2 months versus 24.9 months in cohort A and 5.7 versus 13.1 months in cohort B). In multivariate analysis, after stratification CD4(+) lymphopaenia appeared to be an independent prognostic factor for OS in both cohorts. CD4(+) lymphopaenia correlated with low plasmatic levels of CCL22 that might directly contribute to CD4(+) lymphopaenia.

CONCLUSIONS

CD4(+) lymphopaenia was associated with reduced OS in MBC patients regardless of the chemotherapy line. Decreased levels of plasmatic CCL22 may contribute to CD4(+) lymphopaenia.

Lymphopenia combined with low TCR diversity to predict overall survival in metastatic breast cancer patients

10562

Background: Lymphopenia (<1 Giga/L) before initiation of chemotherapy is a predictive factor for toxicity and death in metastatic phase for cancer patients. Combinatorial diversity of T Cell Receptor beta chain (TCR-ß), as a measure of T cell repertoire diversity, was investigated and tested either alone or in combination with lymphopenia as a prognostic factor for overall survival (OS) in first line treatment of metastatic breast cancer (MBC) patients. Methods: Using semi quantitative multiplex PCR, the V-D-J combinatorial diversity of the TCR was measured on cryo-preserved blood samples from 2 cohorts of MBC patients before the initiation of the first line chemotherapy: in an experimental cohort (cohort A, n=66) and in a validation series (cohort B, n=67). A prognostic score, defined NDL (Number & Diversity of Lymphocytes) combining lymphocyte count and TCR diversity was delineated. Univariate and multivariate analysis of prognostic factors for OS were performed in both cohorts. Results: Lymphopenia (<1 Giga/L) was associated with shorter OS for cohort B while TCR diversity ≤33% (called divpenia) was associated with a reduced OS in cohort A. The combination of lymphopenia with low TCR diversity (called lympho-divpenia) was associated with poor OS compared to patients with either lymphocyte count ≥1 Giga/L or diversity >33% or both, in cohort A (median OS: 7.6 vs 24.5 months, p.value =0.0006) and cohort B (median OS 10.6 vs 22.9 months, p.value =0.0035). In a multivariate analysis, including all significant clinical factors from the univariate analysis (PS, liver metastasis, hemoglobin) lympho-divpenia was found to be an independent prognostic factor in the pooled cohort (A+B) (p=0.005) along with triple negative tumors (p=0.011) and hemoglobin level (11.5 g/dL) (p=0.009). Conclusions: NDL score combining lymphopenia and reduced TCR diversity seems to be a strong prognostic factor for OS and could be use to improve care quality of MBC patients.

P2-12-10: Low TCR Diversity (Divpenia) Is a Prognosis Factor of Overall Survival in Metastatic Breast Cancer

Background: We already showed that lymphopenia (&lt;1000 lymphocytes/μl) or CD4+ T cell lymphopenia (&lt;450/μl) detected before initiation of chemotherapy are prognostic factors for toxicity and death for metastatic breast cancer (MBC) patients. The goal of the present study was to identify the characteristics of the T cells in these lymphopenic patients. TCR diversity was investigated and tested as a prognostic factor for overall survival (OS).

Patients and methods: The ImmunTraCkeR® assay (ImmunID, Grenoble, France), which analyzes through semi quantitative multiplex-PCR the V-D-J combinatorial diversity of TCR-beta chain (TRB), was used to investigate diversity of T cell repertoire on cryopreserved blood samples from a retrospective cohort of MBC patients before chemotherapy administration (n=66). Univariate and multivariate analysis were performed. We then validated our score on a prospective cohort (n=67) using the same eligibility criteria (MBC patients before first line chemotherapy administration).

Results: Using a 33% cutoff for divpenia in our retrospective cohort (T cell diversity below 33%) (average diversity for healthy people is 70%), divpenia was associated with a median OS of 10 months vs 22 months for patients with diversity &gt;33% (logrank p value=0.04). The NDL® score (Numeration Diversity Lymphocytes representation) that combines lymphocyte numeration with TRB diversity, demonstrated that lympho-divpenia (T cell diversity below 33% and lymphopenia below lGiga/L) was associated with a poor OS compared to patients with either lymphocyte &lt;1000/μL & diversity &gt;33% or lymphocyte &gt;1000/μL & diversity &lt;33% or both lymphocyte &gt;1000/μL and diversity &gt;33% (p=0.015). In multivariate analysis, including performance status (PS), hemoglobin level, polynuclear neutrophil count (PNN), age, and liver metastasis, NDL® score was identified as an independent prognostic factor for OS. In our prospective validation cohort, NDL® score was also identified as a prognostic factors for OS (p=0,007), as well as lymphopenia (&lt;1000/μL) (p=0,0003), CD4+ lymphopenia (&lt;450/μL) (p=0,04), menopausal status (p=0,02), hormonal receptor status (estrogen receptor p=0.02; progesterone receptor p=0.002) and lung metastasis (p=0,009). In multivariate analysis, hemoglobin level was the only independent prognostic factor in this cohort.

Conclusion: We showed that Divpenia and NDL® score are prognostic factors for OS in MBC patients. In order to confirm these results, a prospective clinical trial is ongoing on a larger cohort of MBC and lung cancer patients.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-12-10.

Optimal epitope composition after antigen screening using a live bacterial delivery vector: application to TRP-2

Immunotherapeutic approaches, based on the generation of tumor-specific cytotoxic T-lymphocytes (CTL), are currently emerging as promising strategies of anti-tumor therapy. The potential use of attenuated bacteria as engineered vectors for vaccine development offers several advantages, including the stimulation of innate immunity. We developed an attenuated live bacterial vector using the type III secretion system (TTSS) of Pseudomonas aeruginosa to deliver in vivo tumor antigens. Using an inducible and rapid expression plasmid, vaccination with several antigens of different length and epitope composition, including TRp-2, gp100 and MUC18, was evaluated against glioma tumor cells. We observed similar CTL immunity and T-cell receptor (TCR) repertoire diversity with the vaccines, TRP2(125-243), TRP2L(125-376) and TRP2S(291-376). However, only immunization with TRP2L(125-376) induced significant anti-tumor immunity. Taken together, our data indicate the importance of the epitopes composition and/or peptide length of these peptides for inducing cytotoxic T-lymphocyte (CTL) mediated immunity. Characteristics that consistently improved anti-tumor immunity include: long peptides with immunodominant and cryptic CD8(+) epitopes, and strong CD4(+) Th epitopes. Our bacterial vector is versatile, easy-to-use and quick to produce. This vector is suitable for rapid screening and evaluation of antigens of varying length and epitope composition.

Abstract LB-165: Low TCR diversity (divpenia) is a new prognosis factor of overall survival in metastatic breast cancer

Rationale

Lymphopenia (&lt;1000 Lymphocytes/μl) or CD4+ T cell lymphopenia (&lt;450/μl), detected before initiation of chemotherapy are predictive factors for toxicity and death in metastatic solid tumors (Borg et al 2004; Ray Coquard et al 2009).

The goal of the present study was to further identify the characteristics of the T cells in these lymphopenic patients. TCR diversity was investigated and tested as predictive factor for overall survival (OS).

Patients and methods

The ImmunTraCkeR® assay (ImmunID, Grenoble France), which analyzes, through semi quantitative multiplex PCR, the V-D-J combinatorial diversity of TCR-beta chain (TRB), was used to investigate diversity of T cell repertoire on cryopreserved blood samples from a prospective cohort of untreated metastatic breast cancer patients (SEMTOF study)(n=66). Univariate and multivariate analysis of prognostic factors for OS were investigated in this series as well as in a validation series.

Results

A severe T cell Divpenia (T cell diversity below 33%) (average diversity for healthy people is 70%) was associated with median survival of 9 months vs 24 months for the remaining patients (logrank p.value=0.0047). In a multivariate analysis, including haemoglobin level, polynuclear neutrophil count and liver metastasis, divpenia (defined at 30% threshold defined by ROC curve analysis) was identified as an independent prognostic factor. The NDL® score (Numeration Diversity Lymphocytes representation) that combines lymphocytes numeration with TRB diversity, demonstrated that lympho-divpenia (T cell diversity below 33% and lymphopenia at 1Giga/L threshold) was associated with a poor prognosis in term of patients survival compared to patients with either a good numeration or good diversity or both good numeration and diversity (p.value=0.0202). Prognostic value of NDL® score was then evaluated on a prospective validation cohort of 33 patients (logrank p.value=0.002).

Conclusion:

Divpenia, and a combined parameter NDL are predictive factors for survival in metastatic breast cancer patients. An open clinical study (LYMPHOS1) will investigate divpenia and NDL® score in a larger prospective cohort of metastatic breast patients.

Acknowledgments

M.MANUEL is a CIFRE recipient. This work (Proof of Concept “LYMPHOS1”) was financially supported by CLARA (LYON, France)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-165. doi:10.1158/1538-7445.AM2011-LB-165

High diversity of the immune repertoire in humanized NOD.SCID.gamma c-/- mice

The diversity of the human immune repertoire and how it relates to a functional immune response has not yet been studied in detail in humanized NOD.SCID.gammac(-/-) immunodeficient mice. Here, we used a multiplex PCR on genomic DNA to quantify the combinatorial diversity of all possible V-J rearrangements at the TCR-beta chain and heavy chain Ig locus. We first show that the combinatorial diversity of the TCR-beta chain generated in the thymus was well preserved in the periphery, suggesting that human T cells were not vastly activated in mice, in agreement with phenotypic studies. We then show that the combinatorial diversity in NOD.SCID.gammac(-/-) mice reached 100% of human reference samples for both the TCR and the heavy chain of Ig. To document the functionality of this repertoire, we show that a detectable but weak HLA-restricted cellular immune response could be elicited in reconstituted mice after immunization with an adenoviral vector expressing HCV envelope glycoproteins. Altogether, our results suggest that humanized mice express a diversified repertoire and are able to mount antigen-specific immune responses.

Regulatory T cells recruited through CCL22/CCR4 are selectively activated in lymphoid infiltrates surrounding primary breast tumors and lead to an adverse clinical outcome

Immunohistochemical analysis of FOXP3 in primary breast tumors showed that a high number of tumor-infiltrating regulatory T cells (Ti-Treg) within lymphoid infiltrates surrounding the tumor was predictive of relapse and death, in contrast to those present within the tumor bed. Ex vivo analysis showed that these tumor-infiltrating FOXP3(+) T cells are typical Treg based on their CD4(+)CD25(high)CD127(low)FOXP3(+) phenotype, their anergic state on in vitro stimulation, and their suppressive functions. These Ti-Treg could be selectively recruited through CCR4 as illustrated by (a) selective blood Treg CCR4 expression and migration to CCR4 ligands, (b) CCR4 down-regulation on Ti-Treg, and (c) correlation between Ti-Treg in lymphoid infiltrates and intratumoral CCL22 expression. Importantly, in contrast to other T cells, Ti-Treg are selectively activated locally and proliferate in situ, showing T-cell receptor engagement and suggesting specific recognition of tumor-associated antigens (TAA). Immunohistochemical stainings for ICOS, Ki67, and DC-LAMP show that Ti-Treg were close to mature DC-LAMP(+) dendritic cells (DC) in lymphoid infiltrates but not in tumor bed and were activated and proliferating. Furthermore, proximity between Ti-Treg, CD3(+), and CD8(+) T cells was documented within lymphoid infiltrates. Altogether, these results show that Treg are selectively recruited within lymphoid infiltrates and activated by mature DC likely through TAA presentation, resulting in the prevention of effector T-cell activation, immune escape, and ultimately tumor progression. This study sheds new light on Treg physiology and validates CCR4/CCL22 and ICOS as therapeutic targets in breast tumors, which represent a major health problem.

Analysis of the TCR alpha-chain rearrangement profile in human T lymphocytes

The size of the available human alphabeta T cell repertoire is difficult to determine and is open to debate. Empirical analysis of TCR beta-chain diversity reveals approximately 10(6) different beta chains in peripheral blood. Due in part to locus complexity, comparable information for TCR alpha is lacking. Rather, current estimates for human TCR alpha diversity, and hence, total repertoire diversity, are based on theoretical analyses that assume equal probabilities of rearrangement between any V alpha gene and J alpha gene. Here, we report on a systematic locus-wide rearrangement analysis of the TCR alpha-chain in human T cells. We first demonstrate that the V-J alpha recombination in the thymus is not random but depends on the reciprocal V alpha and J alpha position within the locus. Characterization of the frequency of gene usage combined with identification of five previously unrecognized pseudogenes enables us to empirically estimate the human TCR alpha combinatorial repertoire. The number of V-J alpha combinations achieved is approximately 44-56% of the total combinatorial possibilities, significantly lower than theoretical estimates. We also demonstrate that TCR alpha-chain diversity in peripheral T lymphocytes mimics the same general patterns of rearrangement as observed in the thymus, and these patterns appear conserved among different individuals. This unexpected observation indicates that, unlike the TCR beta locus, the human TCR alpha-chain repertoire is primarily predetermined by genetic recombination and its size is restricted by limits on the combinatorial repertoire rather than post-thymic selection.

IMGT/GeneInfo: T cell receptor gamma TRG and delta TRD genes in database give access to all TR potential V(D)J recombinations

BACKGROUND

Adaptative immune repertoire diversity in vertebrate species is generated by recombination of variable (V), diversity (D) and joining (J) genes in the immunoglobulin (IG) loci of B lymphocytes and in the T cell receptor (TR) loci of T lymphocytes. These V-J and V-D-J gene rearrangements at the DNA level involve recombination signal sequences (RSS). Whereas many data exist, they are scattered in non specialized resources with different nomenclatures (eg. flat files) and are difficult to extract.

DESCRIPTION

IMGT/GeneInfo is an online information system that provides, through a user-friendly interface, exhaustive information resulting from the complex mechanisms of T cell receptor V-J and V-D-J recombinations. T cells comprise two populations which express the alphabeta and gammadelta TR, respectively. The first version of the system dealt with the Homo sapiens and Mus musculus TRA and TRB loci whose gene rearrangements allow the synthesis of the alphabeta TR chains. In this paper, we present the second version of IMGT/GeneInfo where we complete the database for the Homo sapiens and Mus musculus TRG and TRD loci along with the introduction of a quality control procedure for existing and new data. We also include new functionalities to the four loci analysis, giving, to date, a very informative tool which allows to work on V(D)J genes of all TR loci in both human and mouse species. IMGT/GeneInfo provides more than 59,000 rearrangement combinations with a full gene description which is freely available at http://imgt.cines.fr/GeneInfo.

CONCLUSION

IMGT/GeneInfo allows all TR information sequences to be in the same spot, and are now available within two computer-mouse clicks. This is useful for biologists and bioinformaticians for the study of T lymphocyte V(D)J gene rearrangements and their applications in immune response analysis.

Role of the T cell receptor alpha chain in the development and phenotype of naturally arising CD4+CD25+ T cells

The T cell receptor alpha chain repertoire and the possible influence of the alpha chain on the development and phenotype of naturally arising mouse CD4+CD25+ T cells have not been extensively analysed. We used all available Valpha-specific monoclonal antibodies and a sensitive multiplex genomic DNA PCR assay to study the Valpha repertoire of CD4+CD25+ T cells in normal mice. To address whether CD4+CD25+ T cells express two TCR alpha chains, we have carried out four-colour flow cytometry using combinations of the available anti-Valpha reagents in mice where one allele of the TCRA locus had been inactivated. Results indicate that the Valpha repertoire of CD4+CD25+ T cells is as diverse as their CD25- partners. In addition, CD4+CD25+ T cells develop normally in Tcralpha+/- mice and we show for the first time that despite expressing only one TCRalpha chain, they retain their characteristic CD4(low), CD3(low), TCRbeta(low), CD5(high), CD45RB(low) and cytoplasmic CD152(high) phenotype.

IMGT/GeneInfo: enhancing V(D)J recombination database accessibility

IMGT/GeneInfo is a user-friendly online information system that provides information on data resulting from the complex mechanisms of immunoglobulin (IG) and T cell receptor (TR) V(D)J recombinations. For the first time, it is possible to visualize all the rearrangement parameters on a single page. IMGT/GeneInfo is part of the international ImMunoGeneTics information system (IMGT), a high-quality integrated knowledge resource specializing in IG, TR, major histocompatibility complex (MHC), and related proteins of the immune system of human and other vertebrate species. The IMGT/GeneInfo system was developed by the TIMC and ICH laboratories (with the collaboration of LIGM), and is the first example of an external system being incorporated into IMGT. In this paper, we report the first part of this work. IMGT/GeneInfo_TR deals with the human and mouse TRA/TRD and TRB loci of the TR. Data handling and visualization are complementary to the current data and tools in IMGT, and will subsequently allow the modelling of V(D)J gene use, and thus, to predict non-standard recombination profiles which may eventually be found in conditions such as leukaemias or lymphomas. Access to IMGT/GeneInfo is free and can be found at http://imgt.cines.fr/GeneInfo.

Quantitative and qualitative changes in V-J alpha rearrangements during mouse thymocytes differentiation: implication for a limited T cell receptor alpha chain repertoire

Knowledge of the complete nucleotide sequence of the mouse TCRAD locus allows an accurate determination V-J rearrangement status. Using multiplex genomic PCR assays and real time PCR analysis, we report a comprehensive and systematic analysis of the V-J recombination of TCR alpha chain in normal mouse thymocytes during development. These respective qualitative and quantitative approaches give rise to four major points describing the control of gene rearrangements. (a) The V-J recombination pattern is not random during ontogeny and generates a limited TCR alpha repertoire; (b) V-J rearrangement control is intrinsic to the thymus; (c) each V gene rearranges to a set of contiguous J segments with a gaussian-like frequency; (d) there are more rearrangements involving V genes at the 3' side than 5' end of V region. Taken together, this reflects a preferential association of V and J gene segments according to their respective positions in the locus, indicating that accessibility of both V and J regions is coordinately regulated, but in different ways. These results provide a new insight into TCR alpha repertoire size and suggest a scenario for V usage during differentiation.

Bcl-2/Bax protein expression in heart, slow-twitch and fast-twitch muscles in young rats growing under chronic hypoxia conditions

We have studied the magnitude of apoptosis in heart, slow-twitch skeletal muscle (soleus) and fast-twitch skeletal muscle (gastrocnemius) of rats exposed to 3 weeks in vivo chronic hypoxia. Apoptosis was evaluated biochemically by DNA laddering and by TUNEL and annexin V-staining. The expression of Bax and Bcl-2 proteins was determined by immunohistochemistry and Western blotting. Western blot analysis revealed only a slight difference in Bax expression among the different tissues under normoxic and hypoxic conditions; therefore we can consider that Bax protein is constitutively expressed in muscle tissues. However a singular pattern of Bcl-2 expression was observed among the different tissues under normoxic conditions. Bcl-2 protein was more expressed in fast-twitch glycolytic muscles than in slow-twitch or oxidative muscles with a highest value found in gastrocnemius (4926 +/- 280 AU), followed by soleus (2138 +/- 200 AU) and a very low expression was displayed in the heart muscle (543 +/- 50 AU). After exposure to hypoxia for 21 days (10% O2), Bcl-2 protein expression markedly increased, (44%) in gastrocnemius, (323%) in soleus and (1178%) in heart, with significant differences (p < 0.05 student t-test), reaching a similar threshold of expression in both types of muscles. Furthermore, no sign of apoptosis was detected by TUNEL assay, annexin V-binding assay or DNA electrophoresis analysis. The latter suggested some indiscriminate fragmentations of DNA without apoptosis. In conclusion, we postulate that these protein modifications could represent a adaptative mechanism allowing a better protection against the lack of oxygen in oxidative muscles by preventing apoptosis.