Sustained immunotolerance in multiple sclerosis after stem cell transplant.

OBJECTIVE: Autologous haematopoietic stem cell transplantation (AHSCT) has the potential to induce sustained periods of disease remission in multiple sclerosis (MS), which is an inflammatory disease of the central nervous system (CNS) characterised by demyelination and axonal degeneration. However, the mechanisms associated with durable treatment responses in MS require further elucidation. METHODS: To characterise the longer term immune reconstitution effects of AHSCT at 24 and 36 months (M) post-transplant, high-dimensional immunophenotyping of peripheral blood mononuclear cells from 22 MS patients was performed using two custom-designed 18-colour flow cytometry panels. RESULTS: The higher baseline frequencies of specific pro-inflammatory immune cells (T-helper-17 (Th17) cells, mucosal-associated invariant T-cells and CNS-homing T-conventional (T-conv) cells observed in MS patients were decreased post-AHSCT by 36M. This was accompanied by a post-AHSCT increase in frequencies and absolute counts of immunoregulatory CD56hi natural killer cells at 24M and terminally differentiated CD8+ CD28- CD57+ cells until 36M. A sustained increase in the proportion of naïve B-cells, with persistent depletion of memory B-cells and plasmablasts was observed until 36M. Reconstitution of the B-cell repertoire was accompanied by a reduction in the frequency of circulating T-follicular helper cells (cTfh) expressing programmed cell death-1 (PD1+ ) at 36M. Associations between frequency dynamics and clinical outcomes indicated only responder patients to exhibit a decrease in Th17, CNS-homing T-conv and PD1+ cTfh pro-inflammatory subsets at 36M, and an increase in CD39+ T-regulatory cells at 24M. INTERPRETATION: AHSCT induces substantial recalibration of pro-inflammatory and immunoregulatory components of the immune system of MS patients for up to 36M post-transplant.

Pregnancy post autologous stem cell transplant with BEAM conditioning for multiple sclerosis.

BACKGROUND: Given the increasing numbers of multiple sclerosis (MS) patients undergoing autologous haematopoietic stem cell transplant (AHSCT) worldwide, and with women of childbearing age overrepresented in the target population, it is increasingly important to review fertility and pregnancy outcomes following AHSCT. OBJECTIVE: To evaluate the rate of pregnancy and complications post-AHSCT for MS. METHOD: Retrospective evaluation of the rate of pregnancy and associated complications in a cohort of patients post-AHSCT with BEAM conditioning for MS since 2010 in a tertiary referral centre. RESULTS: In our ongoing Phase 2 trial of AHSCT for MS, 55 patients have undergone AHSCT with 30 females being of childbearing age at time of transplantation. Four pregnancies occurred following AHSCT. Two pregnancies were carried to term. No maternal or neonatal complications were reported in either case. Two pregnancies were not carried to term due to elective terminations. Both of these patients became pregnant unexpectedly 2 years following AHSCT. Of the 21 male patients, one patient has fathered three children since his AHSCT. There were no newborn complications. CONCLUSIONS: This is the first report to our knowledge on fertility outcomes in both sexes post-AHSCT for MS. Patients of both sexes should be counselled prior to treatment on infertility and contraceptive use.

Prospective phase II clinical trial of autologous haematopoietic stem cell transplant for treatment refractory multiple sclerosis.

BACKGROUND: Autologous haematopoietic stem cell transplantation (AHSCT) has been explored as a therapeutic intervention in multiple sclerosis (MS) over the last two decades; however, prospective clinical trials of the most common myeloablative conditioning regimen, BEAM, are limited. Furthermore, patient selection, optimal chemotherapeutic regimen and immunological changes associated with disease response require ongoing exploration. We present the outcomes, safety and immune reconstitution (IR) of patients with active, treatment refractory MS. METHODS: This study was a single-centre, phase II clinical trial of AHSCT for patients with active relapsing remitting (RRMS) and secondary progressive MS (SPMS). Patients underwent AHSCT using BEAM (carmustine, etoposide, cytarabine, melphalan)+antithymocyte globulin chemotherapeutic regimen. OUTCOMES: The primary outcome was event-free survival (EFS); defined as no clinical or radiological relapses and no disability progression. Multiparameter flow cytometry was performed for evaluation of post-transplant IR in both MS and lymphoma patients receiving the same chemotherapy regimen. RESULTS: Thirty-five patients (20 RRMS, 15 SPMS) completed AHSCT, with a median follow-up of 36 months (range 12-66). The median Expanded Disability Status Scores (EDSS) was 6 (2-7) and patients had failed a median of 4 (2-7) disease modifying therapies. 66% failed treatment with natalizumab. EFS at 3 years was 60%, (70% RRMS). Sustained improvement in EDSS was seen in 15 (44%) of patients. There was no treatment-related mortality. A sustained rise in CD39+ T regulatory cells, immunosuppressive CD56hi natural killer cells and ablation of proinflammatory mucosal-associated invariant T cells was seen for 12 months following AHSCT in patients with MS. These changes did not occur in patients with lymphoma receiving the same chemotherapy for AHSCT. CONCLUSIONS: The EFS in our MS cohort is significantly greater than other high-efficacy immunosuppressive therapies and similar to other AHSCT studies despite a more heavily pretreated cohort. TRIAL REGISTRATION NUMBER: ACTRN12613000339752.

Regenerating Immunotolerance in Multiple Sclerosis with Autologous Hematopoietic Stem Cell Transplant.

Multiple sclerosis (MS) is an inflammatory disorder of the central nervous system where evidence implicates an aberrant adaptive immune response in the accrual of neurological disability. The inflammatory phase of the disease responds to immunomodulation to varying degrees of efficacy; however, no therapy has been proven to arrest progression of disability. Recently, more intensive therapies, including immunoablation with autologous hematopoietic stem cell transplantation (AHSCT), have been offered as a treatment option to retard inflammatory disease, prior to patients becoming irreversibly disabled. Empirical clinical observations support the notion that the immune reconstitution (IR) that occurs following AHSCT is associated with a sustained therapeutic benefit; however, neither the pathogenesis of MS nor the mechanism by which AHSCT results in a therapeutic benefit has been clearly delineated. Although the antigenic target of the aberrant immune response in MS is not defined, accumulated data suggest that IR following AHSCT results in an immunotolerant state through deletion of pathogenic clones by a combination of direct ablation and induction of a lymphopenic state driving replicative senescence and clonal attrition. Restoration of immunoregulation is evidenced by changes in regulatory T cell populations following AHSCT and normalization of genetic signatures of immune homeostasis. Furthermore, some evidence exists that AHSCT may induce a rebooting of thymic function and regeneration of a diversified naïve T cell repertoire equipped to appropriately modulate the immune system in response to future antigenic challenge. In this review, we discuss the immunological mechanisms of IR therapies, focusing on AHSCT, as a means of recalibrating the dysfunctional immune response observed in MS.

Baló's concentric sclerosis and tumefactive demyelination: a shared immunopathogenesis?

Baló's concentric sclerosis (BCS) and tumefactive demyelination (TD) are considered atypical forms of multiple sclerosis (MS). Baló lesions are characterized by concentric rings corresponding to alternating bands of demyelination and relatively preserved myelin (Hu and Lucchinetti, 2009). Tumefactive lesions are pseudotumoural demyelinating lesions of >2 cm and may have an open ring-enhancing magnetic resonance imaging appearance (Hu and Lucchinetti, 2009; Lucchinetti et al., 2008; Altintas et al., 2012). We present a patient who developed limb weakness and focal seizures secondary to a lesion radiologically and histopathologically consistent with BCS who, six months later, developed a tumefactive demyelinating lesion. This is the first description of BCS and TD occurring in the same patient and is particularly notable because of the lack of any other more typical demyelinating lesions on the MRIs. The nature of BCS and TD in relation to more typical multiple sclerosis is discussed.

Progressive neuropsychiatric symptoms and motor impairment.

A 42-year-old white man presented with cognitive impairment and behavioral changes followed by rapidly progressive motor and gait impairment. Magnetic resonance imaging revealed striking multifocal white matter signal change, areas of restricted diffusion, diffuse callosal signal change, and atrophy and hyperintensity of the corticospinal tracts. A broad range of etiologies warrant consideration in this case, including degenerative, vascular, inflammatory, metabolic, and neoplastic diseases.

Application of multiplex ligation-dependent probe analysis to define a small deletion encompassing PMP22 exons 4 and 5 in hereditary neuropathy with liability to pressure palsies.

Hereditary neuropathy with liability to pressure palsies arises as a result of defects at the chromosome 17p11.2-12 locus and in 84% of cases a 1.5 Mb deletion containing the PMP22 gene is detected by analysis that utilises polymorphic (CA)n repeat markers which flank this gene. We report the clinical and electrophysiological findings observed in a kindred with three members affected by HNPP due to a deletion containing exons 4 and 5 of the PMP22 gene. This small deletion cannot be detected using standard analysis with polymorphic (CA)n repeat markers and a definitive diagnosis was made by multiplex ligation-dependent probe analysis of PMP22 exons 1A-5. MLPA can be readily utilised as a routine diagnostic laboratory test to detect the common HNPP 1.5 Mb deletion, as well as the reciprocal 1.5 Mb insertion observed in CMT1A, but has the advantage over other diagnostic techniques of being able to define single exon deletions.

B cell-activating factor belonging to the TNF family (BAFF)-R is the principal BAFF receptor facilitating BAFF costimulation of circulating T and B cells.

BAFF (B cell-activating factor belonging to the TNF family) is a cell survival and maturation factor for B cells, and overproduction of BAFF is associated with systemic autoimmune disease. BAFF binds to three receptors, BAFF-R, transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), and B cell maturation Ag (BCMA). Using specific mAbs, BAFF-R was found to be the predominant BAFF receptor expressed on peripheral B cells, in both humans and mice, and antagonist mAbs to BAFF-R blocked BAFF-mediated costimulation of anti- micro responses. The other BAFF receptors showed a much more restricted expression pattern, suggestive of specialized roles. BCMA was expressed by germinal center B cells, while TACI was expressed predominantly by splenic transitional type 2 and marginal zone B cells, as well as activated B cells, but was notably absent from germinal center B cells. BAFF was also an effective costimulator for T cells, and this costimulation occurs entirely through BAFF-R. BAFF-R, but not TACI or BCMA, was expressed on activated/memory subsets of T cells, and T cells from BAFF-R mutant A/WySnJ mice failed to respond to BAFF costimulation. Thus, BAFF-R is important not only for splenic B cell maturation, but is the major mediator of BAFF-dependent costimulatory responses in peripheral B and T cells.

Adult-onset ataxia telangiectasia due to ATM 5762ins137 mutation homozygosity.

Ataxia telangiectasia (A-T) is an autosomal recessive neurodegenerative disorder that arises because of mutations in the ATM gene. The 5762ins137 A-->G point mutation activates a cryptic splice donor site resulting in a 137 bp intronic insert being aberrantly spliced into the ATM transcript. However, normal ATM transcript also is produced from this affected allele, albeit at significantly reduced levels. An exceptionally mild A-T phenotype occurs as a result of homozygosity for the 5762ins137 mutation because of relative preservation of ATM protein expression/kinase activity.

Immunosuppression in peripheral neuropathy: rationale and reality.

Plasma exchange, intravenous immunoglobulin and corticosteroids continue to be the mainstay of treatment for inflammatory neuropathies. Recent trials demonstrate that combining these therapies is not significantly more effective than single agent treatment. The usefulness of novel immunotherapies and cytotoxic agents is difficult to ascertain because of the treatment of small numbers of patients in open-label studies.