Eveline M. Delemarre

Autologous stem cell transplantation aids autoimmune patients by functional renewal and TCR diversification of regulatory T cells

Autologous hematopoietic stem cell transplantation (HSCT) is increasingly considered for patients with severe autoimmune diseases whose prognosis is poor with standard treatments. Regulatory T cells (Tregs) are thought to be important for disease remission after HSCT. However, eliciting the role of donor and host Tregs in autologous HSCT is not possible in humans due to the autologous nature of the intervention. Therefore, we investigated their role during immune reconstitution and re-establishment of immune tolerance and their therapeutic potential following congenic bone marrow transplantation (BMT) in a proteoglycan-induced arthritis (PGIA) mouse model. In addition, we determined Treg T-cell receptor (TCR) CDR3 diversity before and after HSCT in patients with juvenile idiopathic arthritis and juvenile dermatomyositis. In the PGIA BMT model, after an initial predominance of host Tregs, graft-derived Tregs started dominating and displayed a more stable phenotype with better suppressive capacity. Patient samples revealed a striking lack of diversity of the Treg repertoire before HSCT. This ameliorated after HSCT, confirming reset of the Treg compartment following HSCT. In the mouse model, a therapeutic approach was initiated by infusing extra Foxp3(GFP+) Tregs during BMT. Infusion of Foxp3(GFP+) Tregs did not elicit additional clinical improvement but conversely delayed reconstitution of the graft-derived T-cell compartment. These data indicate that HSCT-mediated amelioration of autoimmune disease involves renewal of the Treg pool. In addition, infusion of extra Tregs during BMT results in a delayed reconstitution of T-cell compartments. Therefore, Treg therapy may hamper development of long-term tolerance and should be approached with caution in the clinical autologous setting.

Neonatal thymectomy reveals differentiation and plasticity within human naive T cells

The generation of naive T cells is dependent on thymic output, but in adults, the naive T cell pool is primarily maintained by peripheral proliferation. Naive T cells have long been regarded as relatively quiescent cells; however, it was recently shown that IL-8 production is a signatory effector function of naive T cells, at least in newborns. How this functional signature relates to naive T cell dynamics and aging is unknown. Using a cohort of children and adolescents who underwent neonatal thymectomy, we demonstrate that the naive CD4+ T cell compartment in healthy humans is functionally heterogeneous and that this functional diversity is lost after neonatal thymectomy. Thymic tissue regeneration later in life resulted in functional restoration of the naive T cell compartment, implicating the thymus as having functional regenerative capacity. Together, these data shed further light on functional differentiation within the naive T cell compartment and the importance of the thymus in human naive T cell homeostasis and premature aging. In addition, these results affect and alter our current understanding on the identification of truly naive T cells and recent thymic emigrants.

Haematopoietic stem cell transplantation for autoimmune diseases

Autologous haematopoietic stem cell transplantation (HSCT) is the only treatment that is able to induce long-term, drug-free and symptom-free remission in several refractory autoimmune rheumatic diseases. Over 3,000 HSCT procedures for rheumatic and nonrheumatic severe autoimmune diseases have been performed worldwide. Specific conditioning regimens are currently used to eradicate the autoreactive immunological memory of patients. Although in vivo immune cell depletion with antithymocyte globulin or anti-CD52 is the norm for many regimens, ex vivo selection of CD34+ stem cells from the graft is controversial. Following the extensive immune depletion associated with serotherapy and chemotherapy, HSCT effectively resets the immune system by renewing the CD4+ T cell compartment, especially the regulatory T cell population. The risk of transplant-related mortality (TRM) within the first 100 days should be weighed against the risk of disease-related mortality, and the careful selection and screening of patients before transplantation is essential. Systemic sclerosis is the first autoimmune disease for which HSCT has been shown, in a randomized, controlled trial, to be associated with increased TRM in the first year but a significant long-term, event-free survival benefit afterwards. In this Review, we discuss the immunological mechanisms of HSCT in various autoimmune diseases and current HSCT regimens. After carefully taking into consideration the risks and benefits of HSCT and alternative therapies, we also discuss the efficacy, complications and proposed indications of this procedure.

TLR9 agonist CpG enhances protective nasal HSP60 peptide vaccine efficacy in experimental autoimmune arthritis

Objectives Peptide-based immune tolerance induction is considered an attractive treatment option for autoimmune diseases. The authors have developed a novel method that can enhance the induction of protective peptide-specific T-cell responses, using a rat arthritis model. The authors focused on the Toll-like receptor 9 ligand CpG, which was shown to stimulate regulatory T-cell proliferation when added to plasmacytoid dendritic cells (pDC) using in-vitro cultures. Methods The peptide used is a heat shock protein 60 epitope (p1) that elicits tolerogenic peptide-specific immune responses in human arthritis patients and was recently shown to have protective capacity as a bystander antigen in the rat adjuvant arthritis model. Rats were treated with three nasal doses of p1, CpG or a combination of p1 and CpG. Antigen-presenting cells were studied in nose-draining lymph nodes (mandibular lymph nodes; MLN) after nasal treatment, and T-cell responses were analysed in joint-draining lymph nodes after arthritis induction. Results Nasal co-administration of p1/CpG significantly augmented the arthritis-protective effect of p1, while CpG treatment alone did not. Co-treatment of p1/CpG increased both the number and activation status of pDC in draining MLN, which was accompanied by amplified p1-specific T-cell proliferation and interleukin (IL)-10 production. During early arthritis, p1-specific IL-10 production was identified at the site of inflammation. P1 and p1/CpG-treated rats showed a greater amount of CD4+FoxP3+ regulatory T cells in the joint-draining lymph nodes, which correlated with lower arthritis scores. Conclusions These clinical and immunological data suggest the use of CpG as a potent adjuvant for mucosal peptide-specific immune therapy in arthritis.

Autologous stem cell transplantation leads to a change in proinflammatory plasma cytokine profile of patients with juvenile dermatomyositis correlating with disease activity.

Juvenile dermatomyositis (JDM) is a rare autoimmune disorder, affecting mainly muscles and skin. The mainstay of treatment is high dose corticosteroids, combined with other immunosuppressive drugs.1 In about 30% of patients, the disease cannot be controlled despite multiple treatment interventions. Autologous stem cell transplantation (aSCT) has been reported as a last resort treatment in refractory patients with autoimmune diseases.2 The main hypothesis for the underlying immunological mechanism is that aSCT resets the immune system and restores immune tolerance following profound lymphodepletion and immune suppression.3 Here, we report three patients with refractory JDM that received aSCT (Clinical information, table 1). A short-term follow-up with detailed clinical information (including imaging before and after aSCT, and immune reconstitution after aSCT) of two patients describing complete remission was reported previously.4 The current follow-up of these patients is more than 5 years showing sustained remission. A third patient (#3) has a follow-up of nearly 3 years. Indication of aSCT for patient 3 was refractory muscle and skin inflammation comparable to the other two patients. Whole body MRI prior to aSCT confirmed active myositis. As muscle tests improved substantially after aSCT, MRI was not repeated post aSCT in this patient. Immune reconstitution …

Restoration of the Immune Balance by Autologous Bone Marrow Transplantation in Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is one of the most frequent autoimmune diseases in childhood and is characterized by chronic inflammation of the synovial fluid in joints. Several drugs are available for the treatment of JIA, including various biological agents that interfere with critical cytokine pathways. Though very effective in suppressing disease activity, none of these drugs can cure the disease and induce a lasting medication free remission. A small proportion of JIA patients will become or are unresponsive to any form of medical treatment. For these severely ill patients autologous bone marrow transplantation (aBMT) is a last resort treatment. aBMT is remarkably effective in suppressing disease activity, with beneficial outcome reported in around 70% of these previously refractory patients. Moreover aBMT is the only treatment that can induce a lasting medication-free-disease remission in these patients. In the very long term (after 7 years of remission) however, some disease relapses are observed, with the disease returning in a less severe form compared to prior aBMT. The exact mechanism of how aBMT is inducing this lasting disease remission is still largely unknown, but data from both animal models and humans suggest a prominent role for regulatory T cells. In this review we reviewed the current views of the cellular mechanisms that lay beneath disease induction of JIA and the disease remission caused by aBMT therapy.

Brief Report: Autologous Stem Cell Transplantation Restores Immune Tolerance in Experimental Arthritis by Renewal and Modulation of the Teff Cell Compartment

Autologous stem cell transplantation (ASCT) induces long‐term drug‐free disease remission in patients with juvenile idiopathic arthritis. This study was undertaken to further unravel the immunologic mechanisms underlying ASCT by using a mouse model of proteoglycan‐induced arthritis (PGIA).

Human neonatal thymectomy induces altered B-cell responses and auto-reactivity

An association between T‐cell lymphopenia and autoimmunity has long been proposed, but it remains to be elucidated whether T‐cell lymphopenia affects B‐cell responses to autoantigens. Human neonatal thymectomy (Tx) results in a decrease in T‐cell numbers and we used this model to study the development of autoreactivity. Two cohorts of neonatally thymectomized individuals were examined, a cohort of young (1–5 years post‐Tx, n = 10–27) and older children (>10 years, n = 26), and compared to healthy age‐matched controls. T‐cell and B‐cell subsets were assessed and autoantibody profiling performed. Early post‐Tx, a decrease in T‐cell numbers (2.75 × 109/L vs. 0.71 × 109/L) and an increased proportion of memory T cells (19.72 vs. 57.43%) were observed. The presence of autoantibodies was correlated with an increased proportion of memory T cells in thymectomized children. No differences were seen in percentages of different B‐cell subsets between the groups. The autoantigen microarray showed a skewed autoantibody response after Tx. In the cohort of older individuals, autoantibodies were present in 62% of the thymectomized children, while they were found in only 33% of the healthy controls. Overall, our data suggest that neonatal Tx skews the autoantibody profile. Preferential expansion and preservation of Treg (regulatory T) cell stability and function, may contribute to preventing autoimmune disease development after Tx.

PReS-FINAL-1006: Autologous bone marrow transplantation in autoimmune, experimental arthritis restores immune homeostasis by renewal of the natural tregs compartment

Autologous bone marrow transplantation (aBMT) is a last resort treatment for patients with refractory juvenile idiopathic arthritis (JIA). It can induce disease remission for 80 months after transplantation. Unfortunately, relapses also occur. The underlying working mechanisms remain largely unknown.

Autologous stem cell transplantation in autoimmune arthritis restores immune homeostasis by renewal of the natural Treg compartment

Autologous stem cell transplantation (ASCT) is a last resort treatment for refractory juvenile idiopathic arthritis (JIA). It has been shown to induce dramatic and long-term improvements, but the underlying mechanisms remain to be elucidated. We investigated the potential role of regulatory T cells (Treg) in the processes of immune reconstitution and re-establishment of immune tolerance following ASCT. In a mouse model of proteoglycan-induced arthritis, (pseudo)ASCT following lethal irradiation reduced arthritis scores and restored the immune balance of pro-inflammatory effector T cells and Treg. Directly following the ASCT the majority of Treg consisted of Treg that survived the conditioning and had expanded vigorously. After a few weeks the infused stem cell-derived Treg started dominating the Treg pool and these “new” thymus-derived Treg showed more suppressive capacity than the remaining host Treg including a more stable expression of Foxp3. A therapeutic approach was initiated by infusing extra Foxp3GFPTreg together with the stem cells graft. These Treg expanded vigorously and were still present two months after the ASCT. However, by infusion of Treg the induction of stem cell-derived Treg was delayed and also the restoration of immune tolerance was impaired. These data indicate that restoration of the immune balance following ASCT depends on renewal of the natural Treg pool. Furthermore, infusion of Treg during ASCT seems to have a long-term negative effect on T cell reconstitution and re-establishment of immune tolerance.