BackgroundAutologous 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.MethodsThis 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.OutcomesThe 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.ResultsThirty-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.ConclusionsThe 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 numberACTRN12613000339752.

Autologous haematopoietic stem cell transplantation (AHSCT) is a vital therapeutic option for patients with highly active multiple sclerosis (MS). Rates of remission suggest AHSCT is the most effective form of immunotherapy in controlling the disease. Despite an evolving understanding of the biology of immune reconstitution following AHSCT, the mechanism by which AHSCT enables sustained disease remission beyond the period of lymphopenia remains to be elucidated. Auto-reactive T cells are considered central to MS pathogenesis. Here, we analyse T cell reconstitution for 36 months following AHSCT in a cohort of highly active MS patients. Through longitudinal analysis of sorted naïve and memory T cell clones, we establish that AHSCT induces profound changes in the dominant T cell landscape of both CD4+ and CD8+ memory T cell clones. Lymphopenia induced homeostatic proliferation is followed by clonal attrition; with only 19% of dominant CD4 (p <0.025) and 13% of dominant CD8 (p <0.005) clones from the pre-transplant repertoire detected at 36 months. Recovery of a thymically-derived CD4 naïve T cell repertoire occurs at 12 months and is ongoing at 36 months, however diversity of the naïve populations is not increased from baseline suggesting the principal mechanism of durable remission from MS after AHSCT relates to depletion of putative auto-reactive clones. In a cohort of MS patients expressing the MS risk allele HLA DRB1*15:01, public clones are probed as potential biomarkers of disease. AHSCT appears to induce sustained periods of disease remission with dynamic changes in the clonal T cell repertoire out to 36 months post-transplant.

The evolutionary transition from egg-laying to live-bearing in amniote vertebrates (reptiles and mammals) requires the development of a closer association between the maternal and embryonic tissue to facilitate gas and nutrient exchange with the embryo. Because the embryo is an allograft to the father and mother, it could be considered foreign by the maternal immune system and thus be immunologically rejected during pregnancy. In eutherian ("placental") mammals, the proinflammatory genes interleukin 1B (IL1B), tumor necrosis factor (TNF) and tumor necrosis factor receptor superfamily 1A (TNFRSF1A) are tightly regulated in the pregnant uterus to prevent embryonic rejection. We tested whether inflammation is similarly regulated in pregnant viviparous reptiles by comparing the expression of IL1B, TNF, and TNFRSF1A in the pregnant and nonpregnant uterus of the viviparous lizard, Pseudemoia entrecasteauxii. We found statistically significant support for the downregulation of pregnant uterine TNF mRNA expression in P. entrecasteauxii, but no statistically significant changes in mRNA expression of TNFRSF1A or IL1B between pregnant and nonpregnant uteri. Although these genes are apparently not regulated at the transcriptional level, our immunofluorescence microscopy analyses nonetheless demonstrate that the IL1B proteins are stored intracellularly during pregnancy, possibly resulting in inhibition of inflammatory response. We therefore conclude that processes of both transcriptional (TNF) and posttranslational (IL1B) gene regulation may reduce inflammation in the pregnant uterus of this viviparous reptile. Our study is important because it demonstrates that regulating the maternal immune system to prevent embryonic rejection may be important in reptilian pregnancy as it is in mammalian pregnancy.

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.