Haematopoietic stem cell transplantation for the treatment of systemic sclerosis and other autoimmune disorders

Ab Initio and DFT Study on Cyclophosphamide: Anticancer and Immunomodulating Agents

Cyclophosphamide is presently the most frequently used drug for antineoplastic chemotherapy. It has shown a great response in the treatment of human malignancies including leukemia, lymphoma, germ cell tumours, medulloblastomas, and carcinomas of the breast, lung, and cervix. Cyclophosphamide is also one of the most important immunosuppressive agents. This study investigates the quantum-chemical electronic properties of cyclophosphamide, as well as some of its metabolites, which are computed using ab-initio and DFT calculations. The interaction energy calculations between water molecules and the cyclophosphamide show how, in the solid state, the presence of water of crystallisation will make cyclophosphamide more stable over time. Atomic charges, dipole moment, frontier molecular orbitals, electrostatic potential isosurface, geometric parameters, and proton affinity on every nitrogen site enable the characterisation of the electronic properties and clearly illustrate the reactive sites that could be associated with this biologically important class of molecules.

Interstitial lung disease in systemic sclerosis: where do we stand?

Interstitial lung disease (ILD) is common in systemic sclerosis (SSc) patients and despite recent advances in the treatment is, at present, the major cause of death. Today, an early diagnosis of ILD is possible, and is mandatory to improve the prognosis of the disease. Pulmonary function tests and high-resolution computed tomography remain the mainstay for the diagnosis of SSc-ILD, but there is a growing interest in lung ultrasound. Recently, the correlation between severity of fibrosis and some peripheral blood biomarkers has been described. Nonselective immunosuppressors are still the main treatment for ILD, with cyclophosphamide (CYC) most widely used to obtain remission. Novel therapies towards specific molecular and cellular targets have been suggested; in particular, rituximab (RTX) has shown promising results, but further research is needed. It is of paramount importance to define the severity of the disease and the risk of progression in order to define the need for treatment and the treatment intensity. We propose the division of the treatment strategies at our disposal to induce remission into three categories: high intensity (haematopoietic stem cell transplantation), medium intensity (CYC and RTX) and low intensity (azathioprine (AZA) and mycophenolate mofetil (MMF)). After obtaining remission, maintenance treatment with AZA or MMF should be started. In this review we explore new advances in the pathogenesis, diagnosis and treatment of SSc-ILD.

Is immunosuppressive therapy the anchor treatment to achieve remission in systemic sclerosis?

Since activation of the immune system and a perivascular infiltrate of inflammatory cells are key features of SSc, immunosuppression has long been considered to be an anchor treatment. Non-selective immunosuppression remains central to the treatment of interstitial lung disease (ILD) and skin involvement, with CYC most widely used to obtain remission. The use of MTX as a first-line agent may be considered in the presence of skin involvement without ILD. More recently, MMF has shown encouraging results in observational studies, but still needs more formal evaluation to verify if it can be considered an alternative drug to CYC or a maintenance agent such as AZA. Rituximab has provided promising results in small open-label studies and other novel therapies targeting specific molecular and cellular targets are under evaluation. Patients with rapidly progressing diffuse cutaneous SSc should be evaluated for haematopoietic stem cell transplantation.

B cells in systemic sclerosis: a possible target for therapy

Systemic sclerosis (SSc) is an autoimmune disease characterized by excessive extracellular matrix (ECM) deposition in the skin and other visceral organs and it is associated with immune activation characterized by autoantibody production, release of various cytokines and T-lymphocyte activation. Several recent lines of evidence in animal models and in SSc patients indicate a potential role for B cells in the SSc. B cells have arisen as a possible player in tissue fibrosis in some experimental models and, since IL-6 produced by B cells, along with TGF-β, may induce matrix synthesis and less collagen degradation, targeting B cells could be one way to reduce ECM deposition and reduce the inflammatory background. Both SSc patients and tight-skin mice, a genetic model of SSc, have intrinsic B-cell abnormalities characterized by chronic B-cell activation. SSc patients present an increased number of naïve B cells and an activation of memory B cells, despite a reduction in their number. B cells from SSc patients exhibit increased expression of CD19. Remarkably, CD19 loss or B-cell depletion using antimouse CD20 antibody suppresses the development of skin hyperplasia and autoimmunity in tight-skin mice. Additionally, recent studies revealed a possible beneficial effect of anti-human CD20 antibody (Rituximab) therapy on skin fibrosis and lung involvement in SSc patients. These studies reported also the safety of Rituximab in SSc patients. All these findings suggest a possible role of antiCD20 treatment in SSc patients.

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.

Cyclophosphamide-evoked heart failure involves pronounced co-suppression of cytoplasmic thioredoxin reductase activity and non-protein free thiol level

AIMS

Heart failure is a life-threatening complication of high-dose cyclophosphamide (CTX) chemotherapy, and the present study aimed at identifying the mechanism involved in mice.

METHODS AND RESULTS

CTX at 800 mg/kg resulted in heart failure, in which cytoplasmic thioredoxin reductase (TrxR1) activity and non-protein free thiol (NPFT) level were suppressed by 90 and 62%, respectively. The combination of 350 mg/kg CTX and the glutathione synthesis inhibitor buthionine sulfoximine (BSO) also evoked heart failure, in which TrxR1 activity and NPFT level were suppressed by 66 and 62%, respectively. NPFT depletion alone by BSO did not cause cardiac toxicity. CTX at 350 mg/kg alone also did not cause cardiac toxicity, even though it suppressed TrxR1 activity by 68%. Previous studies have shown that half inactivation of TrxR1 in tumour, bladder, and kidneys was associated with toxicological consequences. Cardiac TrxR1 is dispensable, but cardiac cytoplasmic thioredoxin (Trx1) is essential. The potential uncoupling between TrxR1 and Trx1 may explain why there is no cardiac toxicity following TrxR1 inhibition. However, TrxR1 inactivation may still play a role in CTX-evoked heart failure because inactivated TrxR1 gains cytotoxic function, which may engender noticeable toxicity when massive NPFT is deleted.

CONCLUSION

CTX-evoked heart failure involves pronounced co-suppression of TrxR1 activity and NPFT level.

Interstitial lung disease in systemic sclerosis

We reviewed the literature concerning pathogenesis, clinical features, diagnosis and treatment of interstitial lung disease (ILD) in patients with systemic sclerosis (SSc). ILD is detectable in approximately 70% of patients at autopsy. Nonspecific interstitial pneumonia (NSIP) is the most common pathologic finding. The earliest phase of ILD in SSc is characterized by microvascular injury and alveolitis. Endothelial lesions, activation of coagulation proteases, especially thrombin, fibroblast proliferation, and differentiation of normal lung fibroblasts to a myofibroblasts phenotype are hallmarks of ILD in SSc. Diagnostic procedures used to detect ILD are chest X-ray, high-resolution computed tomography, bronchoalveolar lavage, lung function tests, and sometimes thoracoscopic lung biopsy. Novel and potentially useful methods to diagnose ILD in SSc are induced sputum and technetium-labeled diethylenetriamine pentaacetate (99mTC-DTPA) clearance time. Cyclophosphamide seems to be relatively effective to treat ILD in the earliest phase, but the effects of other immunosuppressive drugs on the lungs are less convincing.

Facilitating cells: Novel promoters of stem cell alloengraftment and donor-specific transplantation tolerance in the absence of GVHD

Bone marrow transplantation (BMT) is the treatment of choice for many hematological malignancies and immunopathologies. Unfortunately, success is often impeded by engraftment failure and graft-versus-host disease (GVHD). A rare bone marrow population known as the facilitating cell (FC) has been identified which facilitates stem cell engraftment and circumvents these obstacles in murine experimental models. This review discusses the identification and characterization of this rare population and provides an emerging portrait of FC origin, ontogeny and function. The promotion of durable stem cell engraftment in MHC disparate recipients, GVHD inhibition and tolerance induction by the FC suggests that future therapies in hematopoietic cell transplantation and tolerance induction for solid organ transplants may be significantly improved through the application of FC transplantation.

Mechanisms and consequences of fibrosis in systemic sclerosis

Systemic sclerosis (SSc), also known as scleroderma, is a complex connective tissue disease that is associated with a high mortality and is challenging to treat because of its clinical heterogeneity and a lack of effective antifibrotic therapies. SSc has vascular, immunologic and fibrotic components that are pathologically interconnected. A growing understanding of the molecular and cellular mechanisms that underlie SSc pathogenesis provides logical and novel approaches to treatment. At present most therapies are organ-based. Vascular and inflammatory components of the disease can also be treated, but effective antifibrotic therapies are lacking. A number of key molecular mediators have the potential to alter immune-cell, vascular and fibrotic processes and these mediators, which include transforming growth factor-beta isoforms, endothelin-1, connective-tissue growth factor, chemokines and members of the interleukin family, are attractive targets for therapeutic modulation. Key mediators can be blocked using antibodies, soluble receptors, endogenous inhibitors or small-molecule antagonists of ligands, receptors or signaling intermediates. Overall, this is an exciting time for new therapies in SSc and advances are being made in synchrony with an improved understanding of the molecular and biochemical basis of the disease.

Transmission of donor illness by stem cell transplantation: should screening be different in older donors?

With increasing donor age, the potential of transmitting diseases from donor to recipient reaches new dimensions. Potentially transmittable diseases from donors include infections, congenital disorders, and acquired illnesses like autoimmune diseases or malignancies of hematological or nonhematological origin. While established nonmalignant or malignant diseases might be easy to discover, early-stage hematological diseases like CML, light-chain multiple myelomas, aleukemic leukemias, occult myelodysplastic syndromes and other malignant and nonmalignant diseases might not be detectable by routine screening but only by invasive, new and/or expensive diagnostic tests. In the following article, we propose recommendations for donor work-up, taking into consideration the age of the donors. In contrast to blood transfusions, stem cells from donors with abnormal findings might still be acceptable for HCT, when no other options are available and life expectancy is limited. This issue is discussed in detail in relation to the available donor and stem cell source. Finally, the recommendations presented here aim at harmonized worldwide work-up for donors to insure high standard quality.

Altered B lymphocyte function induces systemic autoimmunity in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by excessive extracellular matrix deposition in the skin and visceral organs. SSc is associated with immune activation characterized by autoantibody production, lymphocyte activation, and release of various cytokines. The presence of autoantibodies is a central feature of immune activation in SSc. Although autoantibodies are thought to be closely linked to the pathogenesis of SSc, the pathogenic relationship between systemic autoimmunity and the clinical manifestations of SSc, including skin fibrosis, remains unknown. Recent studies have revealed that B cells play a critical role in systemic autoimmunity and disease expression through various functions, including cytokine production in addition to autoantibody production. The B cell signaling thresholds are regulated by response regulators that augment or diminish B cell signals during responses to self and foreign antigens. Abnormal regulation of the response regulator function and expression may result in autoantibody production. Among these response regulators, CD19, which is a critical cell-surface signal transduction molecule of B cells, is the most potent positive regulator. Transgenic mice that overexpress CD19 by approximately 3-fold lose tolerance and generate autoantibodies spontaneously. B cells from SSc patients exhibit a 20%-increase in CD19 expression that induces SSc-specific autoantibody production in transgenic mice. Furthermore, SSc patients have intrinsic B cell abnormalities characterized by expanded naive B cells, activated but diminished memory B cells, and chronic hyper-reactivity of memory B cells, possibly due to CD19 overexpression. Similarly, B cells from a tight-skin mouse, a model of SSc, show augmented CD19 signaling and chronic hyper-reactivity. Remarkably, CD19 loss results in inhibition of chronic B cell hyper-reactivity and elimination of autoantibody production, which is associated with improvement in skin fibrosis and a parallel decrease in IL-6 production by B cells. Thus, chronic B cell activation resulting from augmented CD19 signaling leads to skin fibrosis possibly through IL-6 overproduction, as well as autoantibody production, in tight-skin mice and SSc patients.

Haematopoietic stem cell transplantation for autoimmune disease: limits and future potential

Stem cell transplantation (SCT) for autoimmune disease is handicapped by a lack of definitive clinical trials able to demonstrate an overall benefit. This deficiency will become more problematic as the impetus grows to introduce and evaluate additional technologies intended to improve the safety and efficacy of the procedure. The development of effective surrogate analyses to predict outcome by measuring resurgent autoimmune clones or by genomic- and proteomic-based technologies to detect early disease recurrence may be of value in assessing the benefits of these modifications without the need for full-scale, long-term, randomized trials. The introduction of safer allogeneic transplantation techniques may increase the effectiveness of the procedure, while work on marrow stem cell plasticity and/or fusion suggests that SCT may serve not simply to halt the autoimmune process, but also to contribute cells capable of healing or regenerating diseased organs. Finally, the introduction of therapeutic transgenes into transplanted cells may further increase the effectiveness of SCT, although the regulatory complexities of gene therapy trials will probably delay this process. All these innovations will ensure that the next decade will see major changes in the practice and purpose of SCT for autoimmune disease.