IL-7 engages multiple mechanisms to overcome chronic viral infection and limit organ pathology.

Understanding the factors that impede immune responses to persistent viruses is essential in designing therapies for HIV infection. Mice infected with LCMV clone-13 have persistent high-level viremia and a dysfunctional immune response. Interleukin-7, a cytokine that is critical for immune development and homeostasis, was used here to promote immunity toward clone-13, enabling elucidation of the inhibitory pathways underlying impaired antiviral immune response. Mechanistically, IL-7 downregulated a critical repressor of cytokine signaling, Socs3, resulting in amplified cytokine production, increased T cell effector function and numbers, and viral clearance. IL-7 enhanced thymic output to expand the naive T cell pool, including T cells that were not LCMV specific. Additionally, IL-7 promoted production of cytoprotective IL-22 that abrogated liver pathology. The IL-7-mediated effects were dependent on endogenous IL-6. These attributes of IL-7 have profound implications for its use as a therapeutic in the treatment of chronic viral diseases.

Advanced in immunological monitoring of HIV infection: profile of immune cells and cytokines in people living with HIV-1 in Benin.

BACKGROUND: Immune cells and cytokines have been linked to viremia dynamic and immune status during HIV infection. They may serve as useful biomarkers in the monitoring of people living with HIV-1 (PLHIV-1). The present work was aimed to assess whether cytokines and immune cell profiles may help in the therapeutic follow-up of PLHIV-1. METHODS: Forty PLHIV-1 in treatment success (PLHIV-1s) and fifty PLHIV-1 in treatment failure (PLHIV-1f) followed at the University Hospital of Abomey-Calavi/Sô-Ava in Benin were enrolled. Twenty healthy persons were also recruited as control group. Circulating cytokines and immune cells were quantified respectively by ELISA and flow cytometry. RESULTS: PLHIV-1 exhibited low proportions of CD4 + T cells, NK, NKT, granulocytes, classical and non-classical monocytes, and high proportions of CD8 + T cells, particularly in the PLHIV-1f group, compared to control subjects. Eosinophils, neutrophils and B cell frequencies did not change between the study groups. Circulating IFN-γ decreased whereas IL-4 significantly increased in PLHIV-1s compared to PLHIV-1f and control subjects even though the HIV infection in PLHIV-1s downregulated the high Th1 phenotype observed in control subjects. However, Th1/Th2 ratio remained biased to a Th1 phenotype in PLHIV-1f, suggesting that high viral load may have maintained a potential pro-inflammatory status in these patients. Data on inflammatory cytokines showed that IL-6 and TNF-α concentrations were significantly higher in PLHIV-1s and PLHIV-1f groups than in control subjects. Significant high levels of IL-5 and IL-7 were observed in PLHIV-1f compared to controls whereas PLHIV-1s presented only a high level of IL-5. No change was observed in IL-13 levels between the study groups. CONCLUSION: Our study shows that, in addition to CD4/CD8 T cell ratio, NK and NKT cells along with IL-6, TNF-α, IL-5 and IL-7 cytokines could serve as valuable immunological biomarkers in the therapeutic monitoring of PLHIV-1 although a larger number of patients would be necessary to confirm these results.

Outcome of Progressive Multifocal Leukoencephalopathy Treated by Interleukin-7.

OBJECTIVE: Restoring anti-JC virus (JCV) immunity is the only treatment of progressive multifocal leukoencephalopathy (PML). Interleukin-7 is a cytokine that increases number and function of T cells. We analyzed a population of PML patients who received recombinant human IL-7 (rhIL-7) to estimate survival and its determinants. METHODS: After exclusion of patients with missing data or receiving other immunotherapies, findings from 64 patients with proven PML who received rhIL-7 between 2007 and 2020 were retrospectively analyzed. Logistic regression was used to analyze variables associated with one-year survival. RESULTS: Underlying conditions were HIV/AIDS (n = 27, 42%), hematological malignancies (n = 16, 25%), primary immunodeficiencies (n = 13, 20%), solid organ transplantation (n = 4, 6%) and chronic inflammatory diseases (n = 4, 6%). One-year survival was 54.7% and did not differ by underlying condition. Survival was not associated with baseline characteristics, but with a >50% increase in blood lymphocytes (OR 4.1, 95%CI 1.2-14.9) and CD4+ T cells (OR 5.9, 95%CI 1.7-23.3), and a > 1 log copies/mL decrease in cerebrospinal fluid JCV DNA (OR 7.6, 95%CI 1.6-56.1) during the first month after rhIL-7 initiation. Side effects were mainly local and flu-like symptoms (n = 8, 12.5%) and PML-immune reconstitution inflammatory syndrome (IRIS) (n = 5, 8%). INTERPRETATION: In this non-controlled retrospective study, survival did not differ from that expected in HIV/AIDS patients, but might have been improved in those with hematological malignancies, primary immunodeficiencies and transplant recipients. RhIL-7 might have contributed to the increase in blood lymphocytes and decrease in CSF JCV replication that were associated with better survival. ANN NEUROL 2022;91:496-505.

Serum cytokine profiles predict outcomes of chronic hepatitis B patients discontinuing entecavir or tenofovir therapy.

BACKGROUND/PURPOSE: Distinct hepatitis relapse has been observed after discontinuing entecavir (ETV) or tenofovir disoproxil fumarate (TDF) therapy in chronic hepatitis B (CHB) patients. End-of-therapy (EOT) serum cytokines were compared and used for outcome prediction. METHODS: A total of 80 non-cirrhotic CHB patients in a tertiary medical center in Taiwan who discontinued ETV (n = 51) or TDF (n = 29) therapy after fulfilling the APASL guidelines were prospectively enrolled. Serum cytokines were measured at EOT and 3rd month afterwards. Multivariable analysis was performed to predict virological relapse (VR, HBV DNA >2000 IU/mL), clinical relapse (CR, VR and alanine aminotransferase > 2-fold upper limit of normal) and hepatitis B surface antigen (HBsAg) seroclearance. RESULTS: Compared with TDF group, ETV stoppers had greater interleukin 5 (IL-5), IL-12 p70, IL-13, IL-17 A and tumor necrosis factor alpha (TNF-alpha) (all P < 0.05) at EOT. Older age, TDF use, higher EOT HBsAg and IL-18 (Hazard ratio [HR], 1.01; 95% CI, 1.00-1.02) levels at EOT predicted VR, while older age, higher EOT HBsAg and IL-7 (HR, 1.25; 95% CI, 1.00-1.56) levels predicted CR. In TDF stoppers, higher IL-7 (HR, 1.29; 95% CI, 1.05-1.60) and IL-18 (HR, 1.02; 95% CI, 1.00-1.04) levels predicted VR, while IL-7 (HR, 1.34; 95% CI, 1.08-1.65) and interferon-gamma (IFN-gamma) (HR, 1.08; 95% CI, 1.02-1.14) levels predicted CR. A lower EOT HBsAg level was associated with HBsAg seroclearance. CONCLUSION: Distinct cytokine profiles were observed after stopping ETV or TDF. Higher EOT IL-7, IL-18, and IFN-gamma could be probable predictors for VR and CR in patients discontinuing NA therapies.

The Role of IL-7 and IL-7R in Cancer Pathophysiology and Immunotherapy.

Interleukin-7 (IL-7) is a multipotent cytokine that maintains the homeostasis of the immune system. IL-7 plays a vital role in T-cell development, proliferation, and differentiation, as well as in B cell maturation through the activation of the IL-7 receptor (IL-7R). IL-7 is closely associated with tumor development and has been used in cancer clinical research and therapy. In this review, we first summarize the roles of IL-7 and IL-7Rα and their downstream signaling pathways in immunity and cancer. Furthermore, we summarize and discuss the recent advances in the use of IL-7 and IL-7Rα as cancer immunotherapy tools and highlight their potential for therapeutic applications. This review will help in the development of cancer immunotherapy regimens based on IL-7 and IL-7Rα, and will also advance their exploitation as more effective and safe immunotherapy tools.

Preserved Mucosal-Associated Invariant T-Cell Numbers and Function in Idiopathic CD4 Lymphocytopenia.

BACKGROUND: Mucosal-associated invariant T (MAIT) cells constitute a subset of unconventional, MR1-restricted T cells involved in antimicrobial responses as well as inflammatory, allergic, and autoimmune diseases. Chronic infection and inflammatory disorders as well as immunodeficiencies are often associated with decline and/or dysfunction of MAIT cells. METHODS: We investigated the MAIT cells in patients with idiopathic CD4+ lymphocytopenia (ICL), a syndrome characterized by consistently low CD4 T-cell counts (<300 cell/µL) in the absence of HIV infection or other known immunodeficiency, and by susceptibility to certain opportunistic infections. RESULTS: The numbers, phenotype, and function of MAIT cells in peripheral blood were preserved in ICL patients compared to healthy controls. Administration of interleukin-7 (IL-7) to ICL patients expanded the CD8+ MAIT-cell subset, with maintained responsiveness and effector functions after IL-7 treatment. CONCLUSIONS: ICL patients maintain normal levels and function of MAIT cells, preserving some antibacterial responses despite the deficiency in CD4+ T cells. CLINICAL TRIALS REGISTRATION: NCT00867269.

Effect of IL-7 Therapy on Phospho-Ribosomal Protein S6 and TRAF1 Expression in HIV-Specific CD8 T Cells in Patients Receiving Antiretroviral Therapy.

IL-7 therapy has been evaluated in patients who do not regain normal CD4 T cell counts after virologically successful antiretroviral therapy. IL-7 increases total circulating CD4 and CD8 T cell counts; however, its effect on HIV-specific CD8 T cells has not been fully examined. TRAF1, a prosurvival signaling adaptor required for 4-1BB-mediated costimulation, is lost from chronically stimulated virus-specific CD8 T cells with progression of HIV infection in humans and during chronic lymphocytic choriomeningitis infection in mice. Previous results showed that IL-7 can restore TRAF1 expression in virus-specific CD8 T cells in mice, rendering them sensitive to anti-4-1BB agonist therapy. In this article, we show that IL-7 therapy in humans increases the number of circulating HIV-specific CD8 T cells. For a subset of patients, we also observed an increased frequency of TRAF1+ HIV-specific CD8 T cells 10 wk after completion of IL-7 treatment. IL-7 treatment increased levels of phospho-ribosomal protein S6 in HIV-specific CD8 T cells, suggesting increased activation of the metabolic checkpoint kinase mTORC1. Thus, IL-7 therapy in antiretroviral therapy-treated patients induces sustained changes in the number and phenotype of HIV-specific T cells.

Adaptive protocols based on predictions from a mechanistic model of the effect of IL7 on CD4 counts.

In human immunodeficiency virus-infected patients, antiretroviral therapy suppresses the viral replication, which is followed in most patients by a restoration of CD4+ T cells pool. For patients who fail to do so, repeated injections of exogenous interleukin 7 (IL7) are experimented. The IL7 is a cytokine that is involved in the T cell homeostasis and the INSPIRE study has shown that injections of IL7 induced a proliferation of CD4+ T cells. Phase I/II INSPIRE 2 and 3 studies have evaluated a protocol in which a first cycle of three IL7 injections is followed by a new cycle at each visit when the patient has less than 550 CD4 cells/µL. Restoration of the CD4 concentration has been demonstrated, but the long-term best adaptive protocol is yet to be determined. A mechanistic model of the evolution of CD4 after IL7 injections has been developed, which is based on a system of ordinary differential equations and includes random effects. Based on the estimation of this model, we use a Bayesian approach to forecast the dynamics of CD4 in new patients. We propose four prediction-based adaptive protocols of injections to minimize the time spent under 500 CD4 cells/µL for each patient, without increasing the number of injections received too much. We show that our protocols significantly reduce the time spent under 500 CD4 over a period of two years, without increasing the number of injections. These protocols have the potential to increase the efficiency of this therapy.

IL-7 Restores T Lymphocyte Immunometabolic Failure in Septic Shock Patients through mTOR Activation.

T lymphocyte alterations are central to sepsis pathophysiology, whereas related mechanisms remain poorly understood. We hypothesized that metabolic alterations could play a role in sepsis-induced T lymphocyte dysfunction. Samples from septic shock patients were obtained at day 3 and compared with those from healthy donors. T cell metabolic status was evaluated in the basal condition and after T cell stimulation. We observed that basal metabolic content measured in lymphocytes by nuclear magnetic resonance spectroscopy was altered in septic patients. Basal ATP concentration, oxidative phosphorylation (OXPHOS), and glycolysis pathways in T cells were decreased as well. After stimulation, T lymphocytes from patients failed to induce glycolysis, OXPHOS, ATP production, GLUT1 expression, glucose entry, and proliferation to similar levels as controls. This was associated with significantly altered mTOR, but not Akt or HIF-1α, activation and only minor AMPKα phosphorylation dysfunction. IL-7 treatment improved mTOR activation, GLUT1 expression, and glucose entry in septic patients' T lymphocytes, leading to their enhanced proliferation. mTOR activation was central to this process, because rapamycin systematically inhibited the beneficial effect of recombinant human IL-7. We demonstrate the central role of immunometabolism and, in particular, mTOR alterations in the pathophysiology of sepsis-induced T cell alterations. Our results support the rationale for targeting metabolism in sepsis with recombinant human IL-7 as a treatment option.

Interleukin-7 Resensitizes Non-Small-Cell Lung Cancer to Cisplatin via Inhibition of ABCG2.

Treatment with cisplatin (DDP) is one of the standard therapies used to treat non-small-cell lung cancer (NSCLC) and fundamentally causes resistance in cancer cells, which eventually poses as an obstacle to the efficacy of chemotherapy in NSCLC. Efforts are on all over the world to explore a sensitizer of NSCLC to DDP. Here, we studied the effect of IL-7 on the resistance of NSCLC to chemotherapy. We observed that IL-7 treatment significantly enhanced DDP-induced effects in A549 and A549/DDP cells (DDP-resistant cells), including decreased cell viability and proliferation, as well as increased cell apoptosis and S arrest, indicating that IL-7 treatment resensitized DDP-resistant NSCLC cells to DDP. Subsequently, IL-7 enhanced the sensitivity of PI3K/AKT signaling and expressions of ABCG2 to DDP. By inhibiting IL-7 signaling via IL-7R knockdown or activating PI3K/AKT signaling via PI3K activation, the resensitization to DDP by IL-7 was abrogated, and the expression levels of ABCG2, p-PI3K, and p-AKT were found to be significantly higher. In vivo results also confirmed that IL-7 only in combination with DDP could remarkably induce tumor regression with reduced levels of ABCG2 in tumorous tissues. These findings indicate that IL-7, apart from its adjuvant effect, could overcome multidrug resistance of DDP to restore its chemotherapy sensitivity.

Successful treatment of progressive multifocal leukoencephalopathy with recombinant interleukin-7 and maraviroc in a patient with idiopathic CD4 lymphocytopenia.

Progressive multifocal leukoencephalopathy (PML) is a rapidly progressive, often fatal viral infection of the brain without a known treatment. Recently, case reports have demonstrated survival from PML with therapies that improve cell-mediated immunity, including interleukin-7 (IL-7) or the chemokine receptor type 5 (CCR5) antagonist, maraviroc (MVC). We present the first known case of a patient with PML successfully treated with both IL-7 and MVC. A 63-year-old woman presented to our center with a 6-month history of progressive left hemiparesis. Extensive laboratory testing was negative except for a severe CD4 lymphocytopenia (140/µL). Serial brain MRIs done prior to presentation revealed an enlarging, non-enhancing T2-hyperintense lesion in the right fronto-parietal white matter. PML was confirmed through detection of the JC virus by PCR in the cerebrospinal fluid and by brain biopsy, and she was started on mirtazapine and mefloquine. She continued to deteriorate and was then given a course of recombinant IL-7. Though she remained clinically stable after IL-7 treatment and serum JCV PCR decreased from 1000 copies/mL to a nadir of 238 copies/mL, a repeat MRI 3 months later showed lesion enlargement. MVC was then initiated. Now, more than 2 years after initial presentation, she remains stable and serum JCV PCR is undetectable. This case demonstrates successful treatment of PML in a patient with idiopathic CD4 lymphocytopenia and highlights the potential benefits of IL-7 and MVC in the treatment of PML. Treatment with IL-7 and MVC led to clinical stability and improvement in JC virus titers.

Thymic Atrophy: Experimental Studies and Therapeutic Interventions.

The thymus is essential for T cell development and maturation. It is extremely sensitive to atrophy, wherein loss in cellularity of the thymus and/or disruption of the thymic architecture occur. This may lead to lower naïve T cell output and limited TCR diversity. Thymic atrophy is often associated with ageing. What is less appreciated is that proper functioning of the thymus is critical for reduction in morbidity and mortality associated with various clinical conditions including infections and transplantation. Therefore, therapeutic interventions which possess thymopoietic potential and lower thymic atrophy are required. These treatments enhance thymic output, which is a vital factor in generating favourable outcomes in clinical conditions. In this review, experimental studies on thymic atrophy in rodents and clinical cases where the thymus atrophies are discussed. In addition, mechanisms leading to thymic atrophy during ageing as well as during various stress conditions are reviewed. Therapies such as zinc supplementation, IL7 administration, leptin treatment, keratinocyte growth factor administration and sex steroid ablation during thymic atrophy involving experiments in animals and various clinical scenarios are reviewed. Interventions that have been used across different scenarios to reduce the extent of thymic atrophy and enhance its output are discussed. This review aims to speculate on the roles of combination therapies, which by acting additively or synergistically may further alleviate thymic atrophy and boost its function, thereby strengthening cellular T cell responses.

Controlling IL-7 Injections in HIV-Infected Patients.

Immune interventions consisting in repeated injections are broadly used as they are thought to improve the quantity and the quality of the immune response. However, they also raise several questions that remain unanswered, in particular the number of injections to make or the delay to respect between different injections to achieve this goal. Practical and financial considerations add constraints to these questions, especially in the framework of human studies. We specifically focus here on the use of interleukin-7 (IL-7) injections in HIV-infected patients under antiretroviral treatment, but still unable to restore normal levels of [Formula: see text] T lymphocytes. Clinical trials have already shown that repeated cycles of injections of IL-7 could help maintaining [Formula: see text] T lymphocytes levels over the limit of 500 cells/[Formula: see text]L, by affecting proliferation and survival of [Formula: see text] T cells. We then aim at answering the question: how to maintain a patients level of [Formula: see text] T lymphocytes by using a minimum number of injections (i.e., optimizing the strategy of injections)? Based on mechanistic models that were previously developed for the dynamics of [Formula: see text] T lymphocytes in this context, we model the process by a piecewise deterministic Markov model. We then address the question by using some recently established theory on impulse control problem in order to develop a numerical tool determining the optimal strategy. Results are obtained on a reduced model, as a proof of concept: the method allows to define an optimal strategy for a given patient. This method could be applied to optimize injections schedules in clinical trials.

JC virus granule cell neuronopathy in the setting of chronic lymphopenia treated with recombinant interleukin-7.

JC virus (JCV) is a human polyomavirus that infects the central nervous system (CNS) of immunocompromised patients. JCV granule cell neuronopathy (JCV-GCN) is caused by infection of cerebellar granule cells, causing ataxia. A 77-year-old man with iatrogenic lymphopenia presented with severe ataxia and was diagnosed with JCV-GCN. His ataxia and cerebrospinal fluid (CSF) improved with intravenous immunoglobulin, high-dose intravenous methylprednisolone, mirtazapine, and mefloquine. Interleukin-7 (IL-7) therapy reconstituted his lymphocytes and reduced his CSF JCV load. One month after IL-7 therapy, he developed worsening ataxia and CSF inflammation, which raised suspicion for immune reconstitution inflammatory syndrome. Steroids were restarted and his ataxia stabilized.

Treatment with Interleukin-7 Restores Host Defense against Pneumocystis in CD4+ T-Lymphocyte-Depleted Mice.

Pneumocystis pneumonia (PCP) is a major cause of morbidity and mortality in patients with HIV infection. CD4(+) T lymphocytes are critical for host defense against this infection, but in the absence of CD4(+) T lymphocytes, CD8(+) T lymphocytes may provide limited host defense. The cytokine interleukin-7 (IL-7) functions to enhance lymphocyte proliferation, survival, and recruitment of immune cells to sites of infection. However, there is little known about the role of IL-7 in PCP or its potential use as an immunotherapeutic agent. We hypothesized that treatment with recombinant human IL-7 (rhIL-7) would augment host defense against Pneumocystis and accelerate pathogen clearance in CD4-depleted mice. Control and CD4-depleted mice were infected with Pneumocystis, and rhIL-7 was administered via intraperitoneal injection. Our studies indicate that endogenous murine IL-7 is part of the normal host response to Pneumocystis murina and that administration of rhIL-7 markedly enhanced clearance of Pneumocystis in CD4-depleted mice. Additionally, we observed increased recruitment of CD8(+) T lymphocytes to the lungs and decreased apoptosis of pulmonary CD8(+) T lymphocytes in rhIL-7-treated animals compared to those in untreated mice. The antiapoptotic effect of rhIL-7 was associated with increased levels of Bcl-2 protein in T lymphocytes. rhIL-7 immunotherapy in CD4-depleted mice also increased the number of gamma interferon (IFN-γ)-positive CD8(+) central memory T lymphocytes in the lungs. We conclude that rhIL-7 has a potent therapeutic effect in the treatment of murine Pneumocystis pneumonia in CD4-depleted mice. This therapeutic effect is mediated through enhanced recruitment of CD8(+) T cells and decreased apoptosis of lung T lymphocytes, with a preferential action on central memory CD8(+) T lymphocytes.

Repeated Cycles of Recombinant Human Interleukin 7 in HIV-Infected Patients With Low CD4 T-Cell Reconstitution on Antiretroviral Therapy: Results of 2 Phase II Multicenter Studies.

BACKGROUND: Phase I/II studies in human immunodeficiency virus (HIV)-infected patients receiving antiretroviral therapy have shown that a single cycle of 3 weekly subcutaneous (s/c) injections of recombinant human interleukin 7 (r-hIL-7) is safe and improves immune CD4 T-cell restoration. Herein, we report data from 2 phase II trials evaluating the effect of repeated cycles of r-hIL-7 (20 µg/kg) with the objective of restoring a sustained CD4 T-cell count >500 cells/µL. METHODS: INSPIRE 2 was a single-arm trial conducted in the United States and Canada. INSPIRE 3 was a 2 arm trial with 3:1 randomization to r-hIL-7 versus control conducted in Europe and South Africa. Participants with plasma HIV RNA levels <50 copies/mL during antiretroviral therapy and with CD4 T-cell counts between 101 and 400 cells/µL were eligible. A repeat cycle was administered when CD4 T-cell counts fell to <550 cells/µL. RESULTS: A total of 107 patients were treated and received 1 (n = 107), 2 (n = 74), 3 (n = 14), or 4 (n = 1) r-hIL-7 cycles during a median follow-up of 23 months. r-hIL-7 was well tolerated. Four grade 4 events were observed, including 1 case of asymptomatic alanine aminotransferase elevation. After the second cycle, anti-r-hIL-7 binding antibodies developed in 82% and 77% of patients in INSPIRE 2 and 3, respectively (neutralizing antibodies in 38% and 37%), without impact on the CD4 T-cell response. Half of the patients spent >63% of their follow-up time with a CD4 T-cell count >500 cells/µL. CONCLUSIONS: Repeated cycles of r-hIL-7 were well tolerated and achieved sustained CD4 T-cell restoration to >500 cells/µL in the majority of study participants. CLINICAL TRIALS REGISTRATION: INSPIRE II: clinicaltrials.gov (NCT01190111) and INSPIRE III: EudraCT (No. 2010-019773-15) and clinicaltrials.gov (NCT01241643).

Adaptive immune function in critical illness.

PURPOSE OF REVIEW: This review is being published to update the literature on the function of the adaptive immune system in critical illness, specifically sepsis and acute lung injury. We have focused on the role of T cells in these syndromes. RECENT FINDINGS: The adaptive immune response becomes dysfunctional during sepsis and acute lung injury in very similar ways. Many of the abnormalities contribute to morbidity and mortality. Immunoparalysis captures the breadth of the dysfunction in that T-cell functions are broadly suppressed after the early proinflammatory stages of illness. Lymphocyte apoptosis, decreased antigen responsiveness, decreased and altered cytokine expression, upregulation of inhibitory molecules, and expansion of the suppressive regulatory T-cell population are mechanisms involved. Each of these abnormalities can be reversed with improvement in experimental outcomes. SUMMARY: Immunoparalysis of the adaptive immune system occurs in sepsis and acute lung injury, and is critical to the outcome. Blocking the inhibited pathways and immunostimulant cytokines improved lymphocyte function and outcome. Many such blocking agents are already effective for other diseases and could be used for immunoparalysis. Unfortunately, there is no diagnostic marker yet. In order to provide the right therapy at the right time, advancements in immunomonitoring are necessary.

Stromal-Derived Factor-1α and Interleukin-7 Treatment Improves Homeostatic Proliferation of Naïve CD4(+) T Cells after Allogeneic Stem Cell Transplantation.

Graft-versus-host disease (GVHD) impairs immune reconstitution after allogeneic stem cell transplantation (allo-SCT) and effective therapies aimed at restoring T cell counts in GVHD patients have yet to be developed. During GVHD, CD4(+) T cell reconstitution is particularly affected and current models hold that GVHD insult to the peripheral lymphoid niche is responsible for this effect. Here, we show that naïve CD4(+) T cell homeostatic proliferation (HP) is lost during GVHD because of low systemic IL-7 and impaired dendritic cell (DC) regeneration. We assessed factors involved in DC differentiation and found that although fms-like tyrosine kinase 3 ligand (Flt3-L) levels were normal, stromal-derived factor-1α (SDF-1α) was diminished in the blood of GVHD mice. Unlike Flt3-L treatment, the administration of SDF-1α specifically increased CD8α(+) DC numbers and did not worsen GVHD. Importantly, CD4(+) T cell HP was enhanced only when IL-7 and SDF-1α or Flt3L were coadministered, confirming the crucial role of DCs and IL-7 in restoring CD4(+) T cell regeneration during GVHD. Altogether, our results indicate that CD8α(+) DCs are part of the peripheral niche that controls CD4(+) T cell HP and that their depletion, combined with low systemic IL-7, explains how GVHD constrains naïve CD4(+) T cell reconstitution after allo-SCT.

ELYPSE-7: a randomized placebo-controlled phase IIa trial with CYT107 exploring the restoration of CD4+ lymphocyte count in lymphopenic metastatic breast cancer patients.

BACKGROUND: Lymphopenia is a predictive factor for hematological toxicity, progression and early death in advanced cancers including metastatic breast cancer (MBC). CYT107 is a recombinant interleukin 7 (IL-7) (Cytheris, now Revimmune), well tolerated and able to expand lymphocyte pool in humans. The aims of this study were to determine the optimal schedule to deliver CYT107 and to assess its effect on clinical end points. PATIENT AND METHODS: This placebo-controlled, double blind, phase IIa was conducted in MBC patients with <1500/µl lymphocytes treated with capecitabine. Using a 2-by-2 factorial design, 20 patients were randomly allocated to four arms to receive (i) before chemotherapy: CYT107 or placebo; then (ii) during chemotherapy: CYT107 or placebo. The primary end point was CD4+ count changes before and during chemotherapy. Secondary end points were hematological toxicity, safety, overall response, progression-free survival (PFS) and overall survival (OS). Quantification and functional competence of circulating immune cells were also assessed. RESULTS: When administered before chemotherapy, CYT107 induced a significant increase of CD4+ [+148.1% in CYT107 versus +9.9% in placebo groups, (Wilcoxon, P = 0.002)] and CD8+ T-cell counts, including both naïve and memory subsets. When CYT107 was administered during chemotherapy, the magnitude of CD4+ and CD8+ increase was less important. No modulation of immune cell functional competence was observed. CYT107 was well tolerated with no related ≥grade 3 adverse events except 1 fatal suspected unexpected serious adverse reaction (SUSAR) of uncertain relationship. Of the 12 cases evaluable for response, 6 of 7 patients (86%) receiving CYT107 before chemotherapy achieved a response or stabilization, whereas two of five patients (40%) receiving placebo achieved the same result. No significant difference was observed for PFS or OS. CONCLUSION: In lymphopenic MBC, CYT107 increases CD4+ and other T-cell subset counts without altering their function. A larger clinical trial to demonstrate its impact on clinical outcome is warranted. CLINICALTRIALSGOV IDENTIFIER: NCT01362107.

Mechanism of Action of IL-7 and Its Potential Applications and Limitations in Cancer Immunotherapy.

Interleukin-7 (IL-7) is a non-hematopoietic cell-derived cytokine with a central role in the adaptive immune system. It promotes lymphocyte development in the thymus and maintains survival of naive and memory T cell homeostasis in the periphery. Moreover, it is important for the organogenesis of lymph nodes (LN) and for the maintenance of activated T cells recruited into the secondary lymphoid organs (SLOs). The immune capacity of cancer patients is suppressed that is characterized by lower T cell counts, less effector immune cells infiltration, higher levels of exhausted effector cells and higher levels of immunosuppressive cytokines, such as transforming growth factor ß (TGF-ß). Recombinant human IL-7 (rhIL-7) is an ideal solution for the immune reconstitution of lymphopenia patients by promoting peripheral T cell expansion. Furthermore, it can antagonize the immunosuppressive network. In animal models, IL-7 has been proven to prolong the survival of tumor-bearing hosts. In this review, we will focus on the mechanism of action and applications of IL-7 in cancer immunotherapy and the potential restrictions for its usage.