Progressive multifocal leukoencephalopathy genetic risk variants for pharmacovigilance of immunosuppressant therapies

Background

Progressive multifocal leukoencephalopathy (PML) is a rare and often lethal brain disorder caused by the common, typically benign polyomavirus 2, also known as JC virus (JCV). In a small percentage of immunosuppressed individuals, JCV is reactivated and infects the brain, causing devastating neurological defects. A wide range of immunosuppressed groups can develop PML, such as patients with: HIV/AIDS, hematological malignancies (e.g., leukemias, lymphomas, and multiple myeloma), autoimmune disorders (e.g., psoriasis, rheumatoid arthritis, and systemic lupus erythematosus), and organ transplants. In some patients, iatrogenic (i.e., drug-induced) PML occurs as a serious adverse event from exposure to immunosuppressant therapies used to treat their disease (e.g., hematological malignancies and multiple sclerosis). While JCV infection and immunosuppression are necessary, they are not sufficient to cause PML.

Methods

We hypothesized that patients may also have a genetic susceptibility from the presence of rare deleterious genetic variants in immune-relevant genes (e.g., those that cause inborn errors of immunity). In our prior genetic study of 184 PML cases, we discovered 19 candidate PML risk variants. In the current study of another 152 cases, we validated 4 of 19 variants in both population controls (gnomAD 3.1) and matched controls (JCV+ multiple sclerosis patients on a PML-linked drug ≥ 2 years).

Results

The four variants, found in immune system genes with strong biological links, are: C8B, 1-57409459-C-A, rs139498867; LY9 (alias SLAMF3), 1-160769595-AG-A, rs763811636; FCN2, 9-137779251-G-A, rs76267164; STXBP2, 19-7712287-G-C, rs35490401. Carriers of any one of these variants are shown to be at high risk of PML when drug-exposed PML cases are compared to drug-exposed matched controls: P value = 3.50E-06, OR = 8.7 [3.7-20.6]. Measures of clinical validity and utility compare favorably to other genetic risk tests, such as BRCA1 and BRCA2 screening for breast cancer risk and HLA-B^*15:02 pharmacogenetic screening for pharmacovigilance of carbamazepine to prevent Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.

Conclusion

For the first time, a PML genetic risk test can be implemented for screening patients taking or considering treatment with a PML-linked drug in order to decrease the incidence of PML and enable safer use of highly effective therapies used to treat their underlying disease.

Increased Production of B-Cell Activating Cytokines and Altered Peripheral B-Cell Subset Distribution during HIV-Related Classical Hodgkin Lymphoma

Simple Summary

Patients with HIV are at high risk of developing Hodgkin’s lymphoma. This is potentially due to alterations in blood circulating B-lymphocytes and their activating cytokines. We analyzed the distribution of circulating B-lymphocytes and the level of the activating cytokines IL6, IL10 and BAFF in 38 patients with HIV-related Hodgkin’s lymphoma during a 2-year follow-up. We also compared their characteristics at diagnosis with (1) pre-diagnosis serum samples and (2) samples from control HIV-infected subjects without lymphoma. We found an increase in activating cytokines in cases compared to controls. The level of activating cytokines increased in advanced lymphoma. It decreased over time during follow-up. B-lymphocytic count was similar between patients and controls, but their subset distribution differed. There was an overrepresentation of naive B-lymphocytes over memory B-lymphocytes in HIV-associated Hodgkin lymphoma patients, more pronounced in those with advanced lymphoma. Follow-up showed an increase in B-lymphocytic count with an even greater proportion of naive B-cells. Together this suggests that in HIV-infected patients, Hodgkin lymphoma is associated with an altered blood distribution of B-lymphocytic subsets and an increased production of activating cytokines. This environment may contribute to the process of tumorigenesis.

Abstract

Classical Hodgkin Lymphoma incidence increases in HIV-1-infected patients (HIV-cHL). HIV infection is associated with higher B-cell activation. Here, in 38 HIV-cHL patients from the French cohort ANRS-CO16 Lymphovir, we examined longitudinally over 24 months the serum levels of the B-cell activating cytokines IL10, IL6, and BAFF, and blood distribution of B-cell subsets. Fourteen HIV-cHL patients were also compared to matched HIV-infected controls without cHL. IL10, IL6, and BAFF levels were higher in HIV-cHL patients than in controls (p < 0.0001, p = 0.002, and p < 0.0001, respectively). Cytokine levels increased in patients with advanced-stage lymphoma compared to those with limited-stage (p = 0.002, p = 0.03, and p = 0.01, respectively). Cytokine levels significantly decreased following HIV-cHL diagnosis and treatment. Blood counts of whole B-cells were similar in HIV-cHL patients and controls, but the distribution of B-cell subsets was different with higher ratios of naive B-cells over memory B-cells in HIV-cHL patients. Blood accumulation of naive B-cells was more marked in patients with advanced cHL stages (p = 0.06). During the follow-up, total B-cell counts increased (p < 0.0001), and the proportion of naive B-cells increased further (p = 0.04). Together the results suggest that in HIV-infected patients, cHL is associated with a particular B-cell-related environment that includes increased production of B-cell-activating cytokines and altered peripheral distribution of B-cell subsets. This B-cell-related environment may fuel the process of tumorigenesis.

Frequent altered distribution of peripheral B-lymphocyte subsets in pediatric and adolescent patients with classical Hodgkin lymphoma

Peripheral lymphopenia is a well-known negative prognostic marker in classical Hodgkin lymphoma (cHL). We characterized the peripheral B-cell compartment in a prospective cohort of 83 pediatric cHL patients. We observed significantly low total B-cell counts (<100 cells/µl) in 31 of 83 patients (37%). More specifically, there was a smaller peripheral IgD^highCD27^- naïve B-cell pool among B-cell lymphopenic patients than for non-B-cell lymphopenic patients (p < 0.01). The B-cell count was lower in patients without in situ Epstein Barr Virus (EBV) expression than among those with in situ EBV expression (p = 0.03). Peripheral B-cell lymphopenia was associated with the presence of poor prognostic features, such as advanced lymphoma stage (p < 0.01) and the presence of B symptoms (p = 0.04). Of interest, B-cell lymphopenia resolved in all six studied patients in long-term remission. Our findings support that cHL tumor-associated factors interfere with the distribution of peripheral B-cell subsets.

Progressive multifocal leukoencephalopathy on dimethyl fumarate with preserved lymphocyte count but deep T-cells exhaustion

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) among multiple sclerosis (MS) patients receiving dimethyl fumarate (DMF) is associated with iatrogenic lymphopenia, predominating on CD8+ T-cells.

OBJECTIVES AND METHODS

We report an unusual case of DMF-related PML in a 66-year-old MS patient with preserved lymphocyte count (nadir: 810/mm³) and normal CD8+ T-cells count.

RESULTS

A massive overexpression of the inhibitory receptor Programmed Cell Death 1 (PD-1) on CD8+ and memory effector T-cells together with an impaired anti-JC virus (JCV) specific T-cells response were found, compatible with exhaustion. Following DMF withdrawal, PML progressively regressed, PD-1 was downregulated, and a functional anti-JCV response was established.

CONCLUSION

T-cells exhaustion may favor PML onset on DMF independently of lymphocyte count.

Germline Genetic Risk Variants for Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disorder of the brain caused by reactivation of the JC virus (JCV), a polyomavirus that infects at least 60% of the population but is asymptomatic or results in benign symptoms in most people. PML occurs as a secondary disease in a variety of disorders or as a serious adverse event from immunosuppressant agents, but is mainly found in three groups: HIV-infected patients, patients with hematological malignancies, or multiple sclerosis (MS) patients on the immunosuppressant therapy natalizumab. It is severely debilitating and is deadly in ~50% HIV cases, ~90% of hematological malignancy cases, and ~24% of MS-natalizumab cases. A PML risk prediction test would have clinical utility in all at risk patient groups but would be particularly beneficial in patients considering therapy with immunosuppressant agents known to cause PML, such as natalizumab, rituximab, and others. While a JC antibody test is currently used in the clinical decision process for natalizumab, it is suboptimal because of its low specificity and requirement to periodically retest patients for seroconversion or to assess if a patient's JCV index has increased. Whereas a high specificity genetic risk prediction test comprising host genetic risk variants (i.e., germline variants occurring at higher frequency in PML patients compared to the general population) could be administered one time to provide clinicians with additional risk prediction information that is independent of JCV serostatus. Prior PML case reports support the hypothesis that PML risk is greater in patients with a genetically caused immunodeficiency disorder. To identify germline PML risk variants, we performed exome sequencing on 185 PML cases (70 in a discovery cohort and 115 in a replication cohort) and used the gnomAD variant database for interpretation. Our study yielded 19 rare variants (maximum allele frequency of 0.02 in gnomAD ethnically matched populations) that impact 17 immune function genes (10 are known to cause inborn errors of immunity). Modeling of these variants in a PML genetic risk test for MS patients considering natalizumab treatment indicates that at least a quarter of PML cases may be preventable.

Refractory T-Cell Anergy and Rapidly Fatal Progressive Multifocal Leukoencephalopathy After Prolonged CTLA4 Therapy

Progressive multifocal leukoencephalopathy (PML) is a deadly demyelinating disease due to central nervous system replication of the human polyomavirus JC virus (JCV) in immunosuppressed patients. The only effective therapeutic approach is to restore anti-JCV T-cell responses. In this study, we describe a case of rapidly fatal PML with JCV T-cell anergy in a renal transplant patient treated with CTLA4-Ig (belatacept, a CD28-B7 costimulation blocker and T-cell anergy inducer). T-cell anergy could not be reversed despite several therapeutic approaches. Progressive multifocal leukoencephalopathy secondary to biotherapy-induced T-cell anergy may thus represent a subset of PML with major resistance to anti-JCV immune recovery.

Low numbers of blood and salivary natural killer cells are associated with a better response to belimumab in primary Sjögren's syndrome: results of the BELISS study

Introduction

In this study, we sought to address changes in blood lymphocyte subpopulations and labial salivary gland (LSG) inflammation after belimumab treatment in patients with primary Sjögren’s syndrome (pSS) and to identify predictors of response to treatment.

Methods

Sequential blood lymphocyte subsets and LSG biopsies were analysed between week 0 (W0) and W28 in 15 patients with pSS treated with belimumab. Systemic response to treatment was defined as a decrease in the European League Against Rheumatism Sjögren’s Syndrome Disease Activity Index score of ≥3 points at W28.

Results

After belimumab, we observed a decrease in blood B lymphocytes primarily involving CD27-negative/immunoglobulin D–positive naïve B cells (p=0.008). Lymphocytic sialadenitis (focus score >1) that was present in 12 patients (80.0 %) before belimumab treatment became negative in 5 of them after treatment (p=0.03). The median (interquartile range) LSG B-cell/T-cell ratio decreased from 0.58 (0.5–0.67) to 0.50 (0.5–0.5) (p=0.06). B-cell activating factor (BAFF) staining was detected in 11 (78.6 %) of 14 patients before belimumab treatment compared with 7 (50.0 %) of 14 after belimumab therapy (p=0.10). The median percentage of BAFF-positive cells in foci significantly decreased from 27.5 % (10–40) to 5 % (0–20) (p=0.03). A systemic response was achieved in six patients (40 %). The only predictor of response was the presence of a low number of natural killer (NK) cells, both in blood (8.5 % [7–10] vs 11 % [9–21]; p=0.04) and in LSG (20.6/mm³ [20.0–21.4] vs 30.0/mm³ [25.0–100.0], p=0.003). Serum BAFF levels did not influence response to treatment.

Conclusions

Low blood and salivary NK cell numbers are associated with a better response to belimumab. This suggests that two distinct subsets of pSS may exist: one with a predominant type I interferon (IFN)–BAFF–B-cell axis, representing good responders to belimumab; and one with a predominant type II IFN–NK cell axis, representing non-responders.

Trial registration

ClinicalTrials.gov identifier: NCT01160666. Registered 9 July 2010.

High Risk Features Contrast With Favorable Outcomes in HIV-associated Hodgkin Lymphoma in the Modern cART Era, ANRS CO16 LYMPHOVIR Cohort

BACKGROUND

Human immunodeficiency virus (HIV) infection is associated with a high risk of classical Hodgkin's lymphoma (cHL) in the combined antiretroviral therapy (cART) era.

METHODS

We analyzed the characteristics and outcome of HIV-associated cHL diagnosed in the modern cART era. The French ANRS-CO16 Lymphovir cohort enrolled 159 HIV-positive patients with lymphoma, including 68 (43%) with cHL. HIV-HL patients were compared with a series of non-HV-infected patients consecutively diagnosed with HL.

RESULTS

Most patients (76%) had Ann-Arbor stages III-IV and 96% of patients were treated with ABVD. At diagnosis, median CD4 T-cell count was 387/µL and 94% of patients were treated with cART. All patients received cART after diagnosis. Five patients died from early progression (n = 2), sepsis (1) or after relapse (2). Two additional patients relapsed during follow-up. Two-year overall and progression free survivals (PFS) were 94% [95% CI, 89%, 100%] and 89% [82%, 97%], respectively. The only factor associated with progression or death was age with a relative risk of 8.1 [1.0; 67.0] above 45 years. The PFS of Lymphovir patients appeared similar to PFS of HIV-negative patients, 86% [82%, 90%], but patients with HIV infection displayed higher risk features than HIV-negative patients.

CONCLUSIONS

Although high-risk features still predominate in HIV-HL, the prognosis of these patients, treated with cART and mainly ABVD, has markedly improved in the modern cART era and is now similar to non-HIV-infected patients.

Residual HIV-1 replication may impact immune recovery in patients on first-line lopinavir/ritonavir monotherapy

BACKGROUND

Antiretroviral combination therapy raises issues of long-term adherence and toxicity. Initial treatment simplification based on single-drug therapy was investigated in the MONARK trial, which compared first-line lopinavir/ritonavir monotherapy (arm A) with first-line lopinavir/ritonavir + zidovudine/lamivudine tritherapy (arm B). The MONARK trial is registered as a randomized trial at clinical trials.gov under identifier NCT 00234923.

PATIENTS AND METHODS

Immune recovery was compared in patients with undetectable plasma virus (<50 copies/mL) after 60 weeks of treatment (arm A, n = 21; arm B, n = 13).

RESULTS

The week 60 CD4 T cell count and CD4 T cell subset distribution did not differ significantly between the treatment arms. Memory CD4 T cell responses to HIV and recall antigens were better with triple therapy than with monotherapy. The frequencies of activated CD8 T cells and anti-HIV CD8 T cell effector responses were similar in the two arms. However, the repertoire of CD8 T cell effector responses was broader and persistent residual viraemia more frequent (by ultrasensitive PCR) in the monotherapy arm.

CONCLUSIONS

While viral control can be achieved with first-line lopinavir/ritonavir monotherapy, the quality of immune recovery is inferior to that obtained with triple therapy, possibly owing to a higher level of residual viral replication. Thus, the benefits of first-line lopinavir/ritonavir monotherapy in terms of toxicity and adherence might be offset by an increased risk of residual viral replication, which may also fuel latent viral reservoirs.

Antiviral therapy is associated with a better survival in patients with hepatitis C virus and B-cell non-Hodgkin lymphomas, ANRS HC-13 lympho-C study

Hepatitis C virus (HCV) infection increases the risk of B-cell non-Hodgkin lymphomas (B-NHL). Antiviral treatment (AT) can induce hematological responses in patients with marginal zone lymphomas (MZL). The ANRS HC-13 Lympho-C study aimed at a better understanding of the impact of AT on HCV associated B-NHL. This multicentric study enrolled 116 HCV-positive patients with B-NHL between 2006 and 2012. Cytological and histological samples were collected for centralized review. At lymphoma diagnosis, median age was 61 years and gender ratio M/F was 1. Cytohistological distribution was marginal zone lymphoma (MZL) n = 45 (39%), diffuse large B-cell lymphoma (DLBCL) n = 45 (39%), and other types n = 26 (22%). MZL patients had more frequent detection of rheumatoid factor (68% vs. 35%; P = 0.001) and more frequently mixed cryoglobulinemia (74% vs. 44%; P = 0.021) than patients with DLBCL. Among patients receiving AT, a sustained virologic response was achieved in 23 of 38 (61%) patients with MZL and in 9 of 17 (53%) with DLBCL (P = 0.42). Three-year overall survival (OS) and progression-free survival were 78% 95%CI [63-88] and 64% [48-76], respectively, without difference between cytohistological groups. Outcome analysis showed a favorable association between OS and AT in all patients (P = 0.05) and in the subgroup of MZL patients only (P = 0.04). Our data support that AT improves the outcomes of HCV-associated NHLs. The impact of new AT regimen with protease inhibitor needs to be investigated in this setting. [clinicalTrials.gov Identification number NCT01545544]

Efficacy of recombinant human interleukin 7 in a patient with severe lymphopenia-related progressive multifocal leukoencephalopathy

In this study, we report the case of a patient with profound lymphopenia after allogenic bone marrow transplantation who developed severe progressive multifocal leukoencephalopathy. Single-agent recombinant human interleukin-7 therapy was associated with restoration of anti-John Cunningham polyomavirus (JCV) T-cell responses, JCV clearance from cerebrospinal fluid, and a dramatic clinical improvement.

CCL19, a B cell chemokine, is related to the decrease of blood memory B cells and predicts the clinical response to rituximab in patients with rheumatoid arthritis

OBJECTIVE

Migration of B cells from peripheral blood to the synovium in patients with rheumatoid arthritis (RA) may predict clinical response to rituximab (RTX). We undertook this study to investigate whether serum levels of chemokines involved in B cell trafficking are correlated with blood levels of memory B cells or serum levels of B cell activation biomarkers before B cell depletion and whether chemokine levels predict RTX responsiveness.

METHODS

Blood B cell subsets were analyzed by flow cytometry (CD27, IgD), and serum B cell activation biomarkers (rheumatoid factor, anti-cyclic citrullinated peptide, free light chains, IgG, IgA, IgM, and BAFF) were measured in 208 RA patients and 70 control subjects. Serum CCL19, CXCL12, and CXCL13 chemokine levels in patients and controls were determined by enzyme-linked immunosorbent assay. The first course of RTX was administered to RA patients, and the response was evaluated at week 24 according to European League Against Rheumatism (EULAR) criteria. Results were expressed as the odds ratio (OR) and 95% confidence interval (95% CI).

RESULTS

Levels of all chemokines were increased in RA patients compared with controls, and levels were inversely correlated with CD27+ memory B cell frequency. CCL19 and CXCL13 levels correlated with levels of 6 serum B cell biomarkers and 4 serum B cell biomarkers, respectively. By univariate analysis, the CCL19 level was positively associated with EULAR response (OR 1.43 [95% CI 1.08-1.90], P = 0.01). By multivariate analysis, the CCL19 level was predictive of a response to RTX (OR 1.48 [95% CI 1.06-2.06], P = 0.02), but this did not persist after adjustment for autoantibody status.

CONCLUSION

CXCL13 and CCL19 reflect blood B cell disturbances and their levels correlate with those of other serum B cell biomarkers. CXCL13 and CCL19 are, therefore, surrogate measures for serum B cell biomarkers in RA. Serum CCL19 measurement is a new hallmark of the B cell-mediated RA subtype and may predict clinical response to RTX.

Blood memory B cells are disturbed and predict the response to rituximab in patients with rheumatoid arthritis

OBJECTIVE

To examine blood B cell subsets in patients with rheumatoid arthritis (RA) prior to B cell depletion therapy and to assess their potential as predictors of clinical response to rituximab (RTX).

METHODS

Blood B cell subsets were assessed by flow cytometry in 208 RA patients included in an RTX retreatment study (assessed prior to RTX treatment) and in 47 age-matched controls. Expression of BAFF receptor (BAFF-R) on B cells and serum B cell biomarkers was also measured. B cell subsets and BAFF-R expression were compared between RA patient and control populations. Univariate and multivariate analyses were performed to identify baseline factors associated with a European League Against Rheumatism response 24 weeks after 1 cycle of RTX.

RESULTS

Mean ± SD counts of both CD27- naive and CD27+ memory B cells were decreased in RA patients (188.6 ± 121.4/mm(3)) compared with controls (257.3 ± 154.1/mm(3)) (P = 0.001) and were partially restored in patients treated with methotrexate (MTX) plus anti-tumor necrosis factor compared with patients treated with MTX alone. Within the CD27+ memory B cells, the CD27+IgD- switched memory subtype was selectively decreased, irrespective of treatment. The frequency of CD27+ memory B cells correlated inversely with levels of several B cell activation biomarkers in RA. Serum BAFF level and BAFF-R expression was comparable in RA patients and controls. A low baseline CD27+ memory B cell frequency was associated with a greater clinical response to RTX (odds ratio 0.97 [95% confidence interval 0.95-0.99], P = 0.0015).

CONCLUSION

In B cell depletion therapy-naive RA patients, a low frequency of CD27+ memory B cells correlated with levels of serum B cell activation biomarkers and may predict response to RTX. These results suggest that low memory B cell frequency may be indicative of a B cell-driven RA subtype that is more sensitive to B cell depletion therapy.

Improved survival of HIV-1-infected patients with progressive multifocal leukoencephalopathy receiving early 5-drug combination antiretroviral therapy

BACKGROUND

Progressive multifocal leukoencephalopathy (PML), a rare devastating demyelinating disease caused by the polyomavirus JC (JCV), occurs in severely immunocompromised patients, most of whom have advanced-stage HIV infection. Despite combination antiretroviral therapy (cART), 50% of patients die within 6 months of PML onset. We conducted a multicenter, open-label pilot trial evaluating the survival benefit of a five-drug cART designed to accelerate HIV replication decay and JCV-specific immune recovery.

METHODS AND FINDINGS

All the patients received an optimized cART with three or more drugs for 12 months, plus the fusion inhibitor enfuvirtide during the first 6 months. The main endpoint was the one-year survival rate. A total of 28 patients were enrolled. At entry, median CD4+ T-cell count was 53 per microliter and 86% of patients had detectable plasma HIV RNA and CSF JCV DNA levels. Seven patients died, all before month 4. The one-year survival estimate was 0.75 (95% confidence interval, 0.61 to 0.93). At month 6, JCV DNA was undetectable in the CSF of 81% of survivors. At month 12, 81% of patients had undetectable plasma HIV RNA, and the median CD4+ T-cell increment was 105 per microliter. In univariate analysis, higher total and naive CD4+ T-cell counts and lower CSF JCV DNA level at baseline were associated with better survival. JCV-specific functional memory CD4+ T-cell responses, based on a proliferation assay, were detected in 4% of patients at baseline and 43% at M12 (P = 0.008).

CONCLUSIONS

The early use of five-drug cART after PML diagnosis appears to improve survival. This is associated with recovery of anti-JCV T-cell responses and JCV clearance from CSF. A low CD4+ T-cell count (particularly naive subset) and high JCV DNA copies in CSF at PML diagnosis appear to be risk factors for death.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00120367.

B cell activation biomarkers as predictive factors for the response to rituximab in rheumatoid arthritis: a six-month, national, multicenter, open-label study

OBJECTIVE

To examine whether serum B cell markers can predict response to rituximab, a B cell-depleting monoclonal antibody, in patients with refractory rheumatoid arthritis (RA).

METHODS

This rituximab re-treatment dose study (SMART [eSsai MAbthera sur la dose de Re-Traitement]) involved 208 patients with refractory RA. Serum markers of B cell activation (anti-cyclic citrullinated peptide [anti-CCP] antibodies, rheumatoid factor [RF], serum IgG, IgA, and IgM levels, serum κ and λ free light chains, and serum BAFF) were assessed before the first rituximab cycle (1,000 mg on days 1 and 15). Univariate and multivariate analyses were performed to identify factors associated with a European League Against Rheumatism (EULAR) response at 24 weeks.

RESULTS

There were 149 responders (72%). Two baseline factors were associated with a EULAR response at 24 weeks in multivariate analysis: the presence of anti-CCP antibodies or RF (odds ratio 3.5 [95% confidence interval 1.6-7.6]) and a serum IgG concentration above normal (odds ratio 2.11 [95% confidence interval 1.02-4.33]), with synergy between them (odds ratio 6.0 [95% confidence interval 2.2-16.2]).

CONCLUSION

The presence of RF or anti-CCP antibodies and elevated IgG are 2 simple biomarkers that can be used routinely before therapy to predict response to rituximab in patients with refractory RA.

CD25 appears non essential for human peripheral T(reg) maintenance in vivo

Background

IL-2 has been reported to be critical for peripheral T_reg survival in mouse models. Here, we examined T_reg maintenance in a series of paediatric liver transplant recipients who received basiliximab, a therapeutic anti-CD25 monoclonal antibody.

Methodology/Principal Findings

FoxP3⁺ CD4 T cells were analyzed by flow cytometry before liver grafting and more than 9 months later. We found that in vivo CD25 blockade did not lead to T_reg depletion: the proportion of FoxP3⁺ cells among CD4 T cells and the level of FoxP3 expression were both unchanged. IL-2Rβ expression was enhanced in FoxP3⁺ cells both before and after basiliximab treatment, while the level of IL-2Rγ expression was similar in T_regs and non-T_regs. No significant change in the weak or absent expression of IL-7Rα and IL-15Rα expression on FoxP3⁺ cells was observed. Although the proportion of FoxP3⁺ cells among CD4 T cells did not vary, food allergies occurred more rapidly after liver grafting in patients who received basiliximab, raising questions as to T_reg functionality in vivo in the absence of functional CD25.

Conclusions

CD25 appears non essential for human T_reg peripheral maintenance in vivo. However, our results raise questions as to T_reg functionality after therapeutic CD25 targeting.

Resting regulatory CD4 T cells: a site of HIV persistence in patients on long-term effective antiretroviral therapy

Background

In HIV-infected patients on long-term HAART, virus persistence in resting long-lived CD4 T cells is a major barrier to curing the infection. Cell quiescence, by favouring HIV latency, reduces the risk of recognition and cell destruction by cytotoxic lymphocytes. Several cell-activation-based approaches have been proposed to disrupt cell quiescence and then virus latency, but these approaches have not eradicated the virus. CD4⁺CD25⁺ regulatory T cells (Tregs) are a CD4⁺ T-cell subset with particular activation properties. We investigated the role of these cells in virus persistence in patients on long-term HAART.

Methodology/Principal Findings

We found evidence of infection of resting Tregs (HLADR⁻CD69⁻CD25^hiFoxP3⁺CD4⁺ T cells) purified from patients on prolonged HAART. HIV DNA harbouring cells appear more abundant in the Treg subset than in non-Tregs. The half-life of the Treg reservoir was estimated at 20 months. Since Tregs from patients on prolonged HAART showed hyporesponsiveness to cell activation and inhibition of HIV-specific cytotoxic T lymphocyte-related functions upon activation, therapeutics targeting cell quiescence to induce virus expression may not be appropriate for purging the Treg reservoir.

Conclusions

Our results identify Tregs as a particular compartment within the latent reservoir that may require a specific approach for its purging.

Interruption of antiretroviral therapy initiated during primary HIV-1 infection: impact of a therapeutic vaccination strategy combined with interleukin (IL)-2 compared with IL-2 alone in the ANRS 095 Randomized Study

HIV-specific T cell responses play a critical role in the control of infection. We evaluated the impact of immune-based interventions in patients first treated during primary HIV-1 infection (PHI). Forty-three patients were randomized within three groups, to receive either interleukin-2 (IL-2 group), or boosts of ALVAC-HIV (vCP1433) and LIPO-6T followed by interleukin-2 (Vac-IL2 group), compared with no immune intervention (control group), and were monitored for T cell responses. Impact of strategies on viral replication was subsequently assessed during long-term treatment interruption. HIV-specific CD4(+) T cell responses did not change during the study period in immunized patients relative to controls, and vaccination had only a transient effect on interferon-gamma-producing CD8 responses. Viral rebound after treatment interruption was similar in immunized patients and controls. Forty percent of patients had HIV RNA values <10,000 copies/ml 12 weeks after interruption. The cumulative time off treatment represented almost half the total follow-up period. Immunological and virological status during PHI and HIV DNA load at interruption were predictive of the level of viral rebound after treatment interruption, whereas HIV RNA level during PHI and HIV DNA level at interruption were predictive of the time off treatment. Treatment interruption is safe in patients treated early after primary HIV infection. On the basis of this pilot study, HIV immunizations and interleukin-2 appear to have no supplementary benefit.