Induction of tolerance in autoimmune diseases by hematopoietic stem cell transplantation: getting closer to a cure?

[Autologous hematopoietic stem cell transplantation in systemic lupus erythematosus]

Although the treatment options for systemic lupus erythematosus (SLE) have significantly improved over the past years through the introduction of novel targeted biologic therapies, there are still some patients who suffer from refractory and potentially life-threatening courses of the disease. For these patients autologous hematopoietic stem cell transplantation (ASCT) after immunoablative chemotherapy provides a promising treatment option with curative potential. Based on preclinical models, ASCT was first introduced in 1996 and has since been carried out in approximately 300 patients worldwide. Clinical study results confirmed a disease-free survival in approximately 50 % of patients after 5 years despite termination of immunosuppressive treatment. By careful patient selection and improved anti-infection prophylaxis during stem cell therapy, transplantation-associated mortality could be reduced from an initial 13 % to currently an average of 6 %. Meanwhile, mechanistic studies have provided proof of concept that ASCT not only exerts intensified immunosuppressive effects but is also associated with fundamental qualitative changes of the immune system that may rewire a chronic autoimmune system into a naïve and self-tolerant state: in other words immune reset. Overall, ASCT for SLE is still reserved for patients who do not sufficiently respond to standard therapy. Treatment should be carried out in close cooperation with centers specializing in hematology and only within the framework of clinical studies.

Improving safety of autologous haematopoietic stem cell transplantation in patients with Crohn's disease

OBJECTIVE

To evaluate the feasibility and toxicity of autologous haematopoietic stem cell transplantation (HSCT) for the treatment of refractory Crohn's disease (CD).

DESIGN

In this prospective study, patients with refractory CD suffering an aggressive disease course despite medical treatment, impaired quality of life and in whom surgery was not an acceptable option underwent HSCT. Toxicity and complications during the procedure and within the first year following transplantation were evaluated, along with the impact of the introduction of supportive measures on safety outcomes.

RESULTS

26 patients were enrolled. During mobilisation, 16 patients (62%) presented febrile neutropaenia, including one bacteraemia and two septic shocks. Neutropaenia median time after mobilisation was 5 days. 5 patients withdrew from the study after mobilisation and 21 patients entered the conditioning phase. Haematopoietic recovery median time for neutrophils (>0.5×10(9)/L) was 11 days and for platelets (>20×10(9)/L) 4 days. Twenty patients (95%) suffered febrile neutropaenia and three patients (27%) presented worsening of the perianal CD activity during conditioning. Among non-infectious complications, 6 patients (28.5%) presented antithymocyte globulin reaction, 12 patients (57%) developed mucositis and 2 patients (9.5%) had haemorrhagic complications. Changes in supportive measures over the study, particularly antibiotic prophylaxis regimes during mobilisation and conditioning, markedly diminished the incidence of severe complications. During the first 12-month follow-up, viral infections were the most commonly observed complications, and one patient died due to systemic cytomegalovirus infection.

CONCLUSIONS

Autologous HSCT for patients with refractory CD is feasible, but extraordinary supportive measures need to be implemented. We suggest that this procedure should only be performed in highly experienced centres.

The use of hematopoietic stem cells in autoimmune diseases

Hematopoietic stem cells (HSCs) have been shown recently to hold much promise in curing autoimmune diseases. Newly diagnosed Type 1 diabetes individuals have been successfully reverted to normoglycemia by administration of autologous HSCs in association with a nonmyeloablative regimen (antithymocyte globulin + cyclophasmide). Furthermore, recent trials reported positive results by using HSCs in treatment of systemic sclerosis, multiple sclerosis and rheumatoid arthritis as well. Early data suggested that HSCs possess immunological properties that may be harnessed to alleviate the symptoms of individuals with autoimmune disorders and possibly induce remission of autoimmune diseases. Mechanistically, HSCs may facilitate the generation of regulatory T cells, may inhibit the function of autoreactive T-cell function and may reshape the immune system.

Modern Treatments and Stem Cell Therapies for Perianal Crohn's Fistulas

Crohn's disease (CD) is a complex disorder with important incidence in North America. Perianal fistulas occur in about 20% of patients with CD and are almost always classified as complex fistulas. Conventional treatment options have shown different success rates, yet there are data indicating that these approaches cannot achieve total cure and may not improve quality of life of these patients. Fibrin glue, fistula plug, topical tacrolimus, local injection of infliximab, and use of hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC) are newly suggested therapies with variable success rates. Here, we aim to review these novel therapies for the treatment of complex fistulizing CD. Although initial results are promising, randomized studies are needed to prove efficacy of these approaches in curing fistulizing perianal CD.

Pre-induced adult human peripheral blood mononuclear cells migrate widely into the degenerative retinas of rd1 mice

BACKGROUND AIMS

Recent advances in stem cell research have raised the possibility of stem cells repairing or replacing retinal photoreceptor cells that are either dysfunctional or lost in many retinal diseases. Various types of stem cells have been used to replace retinal photoreceptor cells. Recently, peripheral blood stem cells, a small proportion of pluripotent stem cells, have been reported to mainly exist in the peripheral blood mononuclear cells (PBMCs).

METHODS

In this study, the effects of pre-induced adult human PBMCs (hPBMCs) on the degenerative retinas of rd1 mice were investigated. Freshly isolated adult hPBMCs were pre-induced with the use of the conditioned medium of rat retinas for 4 days and were then labeled with chloromethyl-benzamidodialkylcarbocyanine (CM-DiI) and then transplanted into the subretinal space of the right eye of rd1 mice through a trans-scleral approach. The right eyes were collected 30 days after transplantation. The survival and migration of the transplanted cells in host retinas were investigated by whole-mount retinas, retinal frozen sections and immunofluorescent staining.

RESULTS

After subretinal transplantation, pre-induced hPBMCs were able to survive and widely migrate into the retinas of rd1 mice. A few CM-DiI-labeled cells migrated into the inner nuclear layer and the retinal ganglion cell layer. Some transplanted cells in the subretinal space of rd1 host mice expressed the human photoreceptor-specific marker rhodopsin.

CONCLUSIONS

This study suggests that pre-induced hPBMCs may be a potential cell source of cell replacement therapy for retinal degenerative diseases.

Dendritic cells in hepatitis C infection: can they (help) win the battle?

Infection with hepatitis C virus (HCV) is a public health problem; it establishes a chronic course in ~85% of infected patients and increases their risk for developing liver cirrhosis, hepatocellular carcinoma, and significant extrahepatic manifestations. The mechanisms of HCV persistence remain elusive and are largely related to inefficient clearance of the virus by the host immune system. Dendritic cells (DCs) are the most efficient inducers of immune responses; they are capable of triggering productive immunity and maintaining the state of tolerance to self- and non-self antigens. During the past decade, multiple research groups have focused on DCs, in hopes of unraveling an HCV-specific DC signature or DC-dependent mechanisms of antiviral immunity which would lead to a successful HCV elimination strategy. This review incorporates the latest update in the current status of knowledge on the role of DCs in anti-HCV immunity as it relates to several challenging questions: (a) the phenotype and function of diverse DC subsets in HCV-infected patients; (b) the characteristics of non-human HCV infection models from the DCs' point of view; (c) how can in vitro systems, ranging from HCV protein- or peptide-exposed DC to HCV protein-expressing DCs, and in vivo systems, ranging from HCV protein-expressing transgenic mice to HCV-infected non-human primates, be employed to dissect the role of DCs in triggering/maintaining a robust antiviral response; and (d) the prospect of DC-based strategy for managing and finding a cure for HCV infection.

Autologous hematopoietic stem cell transplantation in autoimmune diseases

The term 'autoimmune diseases' encompasses a spectrum of diseases whose clinical manifestations and, possibly, biological features vary widely. The results of conventional treatment are considered unsatisfactory in aggressive forms, with subsets of patients having short life expectancies. Relying on wide experimental evidence and more feeble clinical data, some research groups have used autologous hematopoietic stem cell transplantation (HSCT) in the most disabling autoimmune diseases with the aim of resetting the patient's immune system. Immunoablative conditioning regimens are preferred over their myeloablative counterparts, and some form of in vivo and/or ex vivo T-cell depletion is generally adopted. Despite 15 years' experience, published controlled clinical trials are still lacking, with the evidence so far available coming from pilot studies and registry surveys. In multiple sclerosis, clinical improvement, or at least lasting disease stabilization, can be achieved in the majority of the patients; nevertheless, the worst results are observed in patients with progressive disease, where no benefit can be expected from conventional therapy. Concerning rheumatologic diseases, wide experience has been acquired in systemic sclerosis, with long-term improvements in cutaneous disease being frequently reported, although visceral involvement remains unchanged at best. Autografting has proved to be barely effective in rheumatoid arthritis and quite toxic in juvenile idiopathic arthritis, whereas it leads to clinical remission and the reversal of visceral impairment in the majority of patients with systemic lupus erythematosus. A promising indication is Crohn's disease, in which long-term endoscopic remission is frequently observed. Growing experience with autologous HCST in autoimmune diseases has progressively reduced concerns about transplant-related mortality and secondary myelodysplasia/leukemia. Therefore, a sustained complete remission seems to be within the reach of autografting in some autoimmune diseases; in others, the indications, risks and benefits of autografting need to be better defined. Consequently, the search for new drugs should also be encouraged.

Autoimmune disease: is it a disorder of the microenvironment?

Systemic lupus erythematosus (SLE) is a common systemic autoimmune disease that involves several vital organs including the cardiovascular system, joints, and kidneys. The pathology is characterized by accumulation of autoreactive lymphocytes that attack the patients' own tissues, secretion of autoantibodies and deposition of immune complexes in vital organs. Chronic widespread inflammation is the hallmark of SLE and the target of current therapy. According to recent theories, intonating immune circuits of inflammatory cytokines and immune cells constitute highly specialized targets for SLE therapy, which nonetheless consists for the most part of anti-inflammatory medications and cytotoxic drugs. For advanced autoimmune disorders, cell therapy aiming at introducing "healthy" stem cells has been promising, keeping in mind that in its current state, stem cell therapy is reserved for the most advanced diseases refractory to traditional therapy. Ongoing studies in our laboratories examined the role of the bone marrow microenvironment, in particular, mesenchymal stem cells (MSCs) in the etiopathogenesis of SLE. Specifically, we are testing the hypothesis that, in human SLE mouse model, marrow MSCs are defective structurally and functionally. Preliminary data indicate that structural and functional defects in MSC population from an autoimmune mouse model for human SLE may contribute to this pathology and consequently present a target for cell therapy.

Autologous Haematopoietic Stem Cell Transplantation for the Treatment of Multiple Sclerosis

Introduction: Autologous haematopoietic stem cell transplantation (auto-HSCT) has been performed for severe multiple sclerosis (MS) refractory to standard therapy with increasing frequency worldwide. However, experience in Asia employing this modality in MS has been limited. In this review, we explored the pathophysiology of autoimmunity and the underlying rationale for auto-HSCT in treating autoimmune diseases including MS, as well as existing published pre-clinical and clinical data. We aimed thereby to better understand the utility of treating MS with auto-HSCT and the feasibility of this procedure in Singapore. Methods: A Medline search was performed with the terms “haematopoietic stem cell transplantation”, “multiple sclerosis” and “autoimmune diseases” from 1996 to 2005. Both original papers and review articles were considered. Main Findings: The majority of publications were from Europe or the United States and most clinical series from single centres had relatively small numbers of patients. Worldwide, the number of patients reported has been less than 300 since 1997. Existing data support the feasibility and promise of this procedure and ongoing Phase III trials may serve to confirm this initial experience. Conclusion: Pre-clinical and early clinical data support the rationale for immunoablative therapy for autoimmune disorders. Auto-HSCT for severe MS is a feasible procedure and can be safely performed in centres with experience managing HSCT patients. Key words: Autoimmunity, Induction of tolerance, Progressive multiple sclerosis

Autologous peripheral blood stem cell transplantation for severe multiple sclerosis

We describe the results of a clinical trial to evaluate the feasibility and toxicity of autologous hematopoietic stem cell transplantation (auto-HSCT) for patients with progressive multiple sclerosis (MS). Fifteen patients (all patients with secondary progressive MS) were enrolled. The median expanded disability status scale (EDSS) score at baseline was 6.0 (range, 4.5-7.5). Peripheral blood stem cells were obtained by leukapheresis after mobilization with granulocyte colony-stimulating factor. In 9 patients, CD34+ cell selection was performed with a CliniMACS cell selection system, and 6 patients accepted infusion of unmodified peripheral blood stem cells. The modified BEAM (carmustine, teniposide, cytarabine, and melphalan) was the sole conditioning regimen used. The adverse effects included infections, mucositis, transient hepatotoxicity, and diarrhea. Three patients had flares of neurologic deterioration during mobilization, 8 patients had the same manifestation during transplantation, and 2 patients had similar flares within 3 months of transplantation. Six patients experienced continuous neurologic improvement after transplantation, 5 patients experienced neurologic progression, and 4 patients had stabilization of their disease. The confirmed progression-free rate was 63.8% at 49 months. The results of lymphocyte purging were no better than for no purging. Auto-HSCT proved to be safe and beneficial for some MS patients. Further studies are needed to establish the merit of this procedure for MS patients.

Autoimmunity during lymphopenia: A two-hit model

The immune system has evolved elaborate mechanisms to respond to diverse antigens while minimizing the risk for autoimmune reactivity. During lymphopenia, however, some mechanisms that normally serve to maintain host tolerance are temporarily suspended. Peripheral T cells proliferate in response to self-antigens in lymphopenic hosts, but proliferation toward these same antigens is prevented when T cell numbers are normal. This process, termed homeostatic peripheral expansion, augments peripheral T cell number and limits repertoire skewing during recovery from lymphopenia and also predisposes lymphopenic hosts to autoimmune disease. This paper reviews murine and human settings in which autoimmunity occurs in the context of lymphopenia. We propose a two-hit model, in which lymphopenia plus another insult is sufficient to induce autoimmune disease. Among the secondary insults that appear sufficient to induce autoimmunity during lymphopenia are overproduction of IL-21 as occurs in the NOD.SCID mouse, depletion of Tregs as demonstrated in murine colitis and gastritis models, and tissue inflammation as seen in HIV infected patients who develop immune reconstitution inflammatory syndrome (IRIS). Delineating critical cofactors which result in autoimmune disease during lymphopenia can provide insight into the pathophysiology of naturally occurring autoimmune diseases as well as generating testable hypothesis for inducing tumor-specific autoimmunity in lymphopenic hosts with cancer.

Granulocyte colony-stimulating factor: a novel mediator of T cell tolerance

In recent years, several investigators have unraveled a previously unrecognized role for G-CSF in the regulation of T cell and dendritic cell functions. The experimental evidence in favor of G-CSF-mediated immune regulation includes the ability to switch T cell cytokine secretion profile to Th2 responses and the promotion of regulatory T cell and tolerogenic dendritic cell differentiation. Interestingly, G-CSF is beneficial in animals for the prevention and/or treatment of immune-mediated diseases, e.g., graft-vs-host disease, multiple sclerosis, systemic lupus erythematosus, inflammatory bowel disease, and diabetes, suggesting a potential role in human autoimmune diseases. This review summarizes the growing body of evidence that supports a critical role for G-CSF as a novel mediator of T cell tolerance.

Autologous haematopoietic stem cell transplantation for Behcet's disease with pulmonary involvement: analysis after 5 years of follow up

BACKGROUND

Myeloablative chemotherapy and autologous haematopoietic stem cell transplantation (HSCT) may provide a therapeutic option in severe Behçet's disease (BD) with pulmonary involvement.

CASE REPORTS

Two patients with BD with pulmonary involvement refractory to conventional immunosuppressive treatment underwent HSCT 1999. Stem cells were mobilised with cyclophosphamide (2 and 4 g/m(2)) and subsequently enriched ex vivo for CD34+ cells. The conditioning regimen used was melphalan (200 mg/m(2)). Outcome was measured by improvement of clinical features, function of affected organs, serological markers, need for immunosuppressive chemotherapy after transplant, and relapse. In both cases HSCT was successful, with good response and without serious complications. After 5 years of follow up one patient is in complete remission without immunosuppressive drugs and one has partial remission, needing low dose corticosteroids (8 mg/day).

CONCLUSION

In these two patients myeloablative chemotherapy, followed by HSCT could be performed safely with marked improvement. In comparison with other observational studies the duration of more than 5 years of remission is remarkable, and its full duration is still unknown.

Autologous hematopoietic stem cell transplantation for autoimmune diseases

Experimental data and early phase I/II studies suggest that high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (HSCT) can arrest progression of severe autoimmune diseases. We have evaluated the toxicity and disease response in 473 patients with severe autoimmune disease treated with autologous HSCT between 1995 and 2003, from 110 centers participating in the European Group for Blood and Marrow Transplantation (EBMT) autoimmune disease working party database. Survival, transplant-related mortality, treatment response and disease progression were assessed. In all, 420 patients (89%; 86+/-4% at 3 years, median follow-up 20 months) were alive, 53 (11%) had died from transplant-related mortality (N=31; 7+/-3% at 3 years) or disease progression (N=22; 9+/-4% at 3 years). Of 370 patients, 299 evaluable for response (81%) showed a treatment response, which was sustained in 213 (71% of responders). Response was associated with disease (P<0.001), was better in patients who received cyclophosphamide during mobilization (relative risk (RR)3.28 (1.57-6.83)) and was worse with increasing age (>40 years, RR0.29 (0.11-0.82)). Disease progression was associated with disease (P<0.001) and conditioning intensity (high intensity, RR1; intermediate intensity, RR1.81 (0.96-3.42)); low intensity, RR2.34 (1.074-5.11)). These data from the collective EBMT experience support the hypothesis that autologous HSCT can alter disease progression in severe autoimmune disease.

Complete remission of alopecia universalis after allogeneic hematopoietic stem cell transplantation

This case report is on a 40-year-old male patient with chronic myeloid leukemia (CML) receiving an allogeneic hematopoietic stem cell transplantation (HSCT) in first chronic phase from an HLA-identical sibling brother. He suffered from alopecia universalis occurring 11 years previously. The alopecia involved all body hair, including eyebrows and eyelashes. Between day 40 and day 55 after transplantation, hair started to grow on the chin, eyelashes, and on the top of his head. Immunosuppression was stopped at 6 months because of cytogenetic relapse and incomplete donor chimerism with some renewed hair loss. He returned to full donor chimerism with mild chronic graft-versus-host disease and continued hair growth. With 2 years of follow-up he has remained in continuous remission. Chimerism analyses of hair follicles did not show any donor alleles. Alopecia universalis is probably a chronic autoimmune disorder, curable with replacement of the immune system with an allogeneic HSCT. (Blood. 2005;105:426-427)

Cell therapy for autoimmune diseases: does it have a future?

Almost all current therapeutic concepts in autoimmune diseases are based on the systemic suppression of immune functions and are not curative. The recent introduction of biologicals such as tumour necrosis factor blocking antibodies or receptors has added greater specificity to efficient management of disease by targeted suppression of rheumatic inflammation. It is evident, however, that only the elimination of the cells secreting inflammatory mediators, rather than the blockade of secreted molecules, will offer real specific therapeutic advantages in the future. Merely the elimination of such cells and also cells controlling the secreting effector cells could be curative and induce true long term remissions. We review here the state of the art and future therapeutic concepts that are based on the specific modulation of pathogenic cells that induce and sustain autoimmune inflammation. This sounds visionary, however, a variety of basic tools are at hand now. Thus, direct and specific cell therapy of rheumatic diseases will become a true alternative to conventional therapies.

Disappearance of diffuse calcinosis following autologous stem cell transplantation in a child with autoimmune disease

A 12-year-old girl presented with arthritis, myalgia, anemia and positive ANA. Subsequently, she developed recurrent episodes of pulmonary hemorrhage, thrombocytopenia, CNS abnormalities, skin ulcers and diffuse calcinosis. This was followed by secondary antiphospholipid syndrome. Despite vigorous immunosuppression, the patient became bedridden. A peripheral blood stem cell autograft was offered when she developed pulmonary hypertension and digital ischemia at the age of 16 years. The post-transplantation course was uneventful. Liquefaction of calcinosis nodules with improvement of mobility occurred gradually. She is now 24 months post-transplant with no sign of disease activity and total disappearance of calcinosis nodules.

Induction of graft-versus-autoimmune (GVA) disease effect against refractory psoriasis by complete donor-type chimerism and graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

A 67-year-old man with AML, who had a 21-year history of psoriasis without remission, received a reduced-intensity transplantation from an HLA-identical sibling. The preparative regimen consisted of busulfan and fludarabine. Graft-versus-host-disease (GVHD) prophylaxis was cyclosporine and methotrexate. Psoriasis was completely resolved on day 18. The subsequent clinical course was uneventful until day 42, when psoriasis recurred at the same sites as before RIST. Peripheral blood examined on day 63 showed mixed chimerism with 54% recipient type. Cyclosporine was rapidly tapered off over the next 2 weeks. On day 90, 100% donor-type chimerism was confirmed. Subsequently, psoriasis improved simultaneously with the occurrence of mucositis and rash as a manifestation of GVHD. Scattered erythematous patches of psoriasis disappeared again by day 105. We initiated 0.5 mg/kg prednisolone on day 119, and resumed cyclosporine on day 133. At 7 months after RIST, he still suffers from chronic GVHD, but his psoriasis remains in remission for the first time in 21 years. The anti-psoriasis effect of the conditioning is mild and transient, while the graft-versus-autoimmunity effect, related to the induction of complete donor-type chimerism and GVHD, is more profound and persisting. A graft-versus-autoimmunity effect lies in the delicate balance between alloimmunity and immunosuppressant used for GVHD prophylaxis/treatment.