BackgroundThe diagnostic and pathophysiological relevance of antibodies to aquaporin-4 (AQP4-Ab) in patients with neuromyelitis optica spectrum disorders (NMOSD) has been intensively studied. However, little is known so far about the clinical impact of AQP4-Ab seropositivity.ObjectiveTo analyse systematically the clinical and paraclinical features associated with NMO spectrum disorders in Caucasians in a stratified fashion according to the patients' AQP4-Ab serostatus.MethodsRetrospective study of 175 Caucasian patients (AQP4-Ab positive in 78.3%).ResultsSeropositive patients were found to be predominantly female (p < 0.0003), to more often have signs of co-existing autoimmunity (p < 0.00001), and to experience more severe clinical attacks. A visual acuity of ≤ 0.1 during acute optic neuritis (ON) attacks was more frequent among seropositives (p < 0.002). Similarly, motor symptoms were more common in seropositive patients, the median Medical Research Council scale (MRC) grade worse, and MRC grades ≤ 2 more frequent, in particular if patients met the 2006 revised criteria (p < 0.005, p < 0.006 and p < 0.01, respectively), the total spinal cord lesion load was higher (p < 0.006), and lesions ≥ 6 vertebral segments as well as entire spinal cord involvement more frequent (p < 0.003 and p < 0.043). By contrast, bilateral ON at onset was more common in seronegatives (p < 0.007), as was simultaneous ON and myelitis (p < 0.001); accordingly, the time to diagnosis of NMO was shorter in the seronegative group (p < 0.029). The course of disease was more often monophasic in seronegatives (p < 0.008). Seropositives and seronegatives did not differ significantly with regard to age at onset, time to relapse, annualized relapse rates, outcome from relapse (complete, partial, no recovery), annualized EDSS increase, mortality rate, supratentorial brain lesions, brainstem lesions, history of carcinoma, frequency of preceding infections, oligoclonal bands, or CSF pleocytosis. Both the time to relapse and the time to diagnosis was longer if the disease started with ON (p < 0.002 and p < 0.013). Motor symptoms or tetraparesis at first myelitis and > 1 myelitis attacks in the first year were identified as possible predictors of a worse outcome.ConclusionThis study provides an overview of the clinical and paraclinical features of NMOSD in Caucasians and demonstrates a number of distinct disease characteristics in seropositive and seronegative patients.

Key Points• The total number of somatic mutations was inversely correlated with survival and risk of leukemic transformation in MPN.• The great majority of somatic mutations were already present at MPN diagnosis, and very few new mutations were detected during follow-up.Myeloproliferative neoplasms (MPNs) are a group of clonal disorders characterized by aberrant hematopoietic proliferation and an increased tendency toward leukemic transformation. We used targeted next-generation sequencing (NGS) of 104 genes to detect somatic mutations in a cohort of 197 MPN patients and followed clonal evolution and the impact on clinical outcome. Mutations in calreticulin (CALR) were detected using a sensitive allele-specific polymerase chain reaction. We observed somatic mutations in 90% of patients, and 37% carried somatic mutations other than JAK2 V617F and CALR. The presence of 2 or more somatic mutations significantly reduced overall survival and increased the risk of transformation into acute myeloid leukemia. In particular, somatic mutations with loss of heterozygosity in TP53 were strongly associated with leukemic transformation. We used NGS to follow and quantitate somatic mutations in serial samples from MPN patients. Surprisingly, the number of mutations between early and late patient samples did not significantly change, and during a total follow-up of 133 patient years, only 2 new mutations appeared, suggesting that the mutation rate in MPN is rather low. Our data show that comprehensive mutational screening at diagnosis and during follow-up has considerable potential to identify patients at high risk of disease progression.

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Although astrogliosis and microglia activation are characteristic features of multiple sclerosis (MS) and other central nervous system (CNS) lesions the exact functions of these events are not fully understood. Animal models help to understand the complex interplay between the different cell types of the CNS and uncover general mechanisms of damage and repair of myelin sheaths. The so called cuprizone model is a toxic model of demyelination in the CNS white and gray matter, which lacks an autoimmune component. Cuprizone induces apoptosis of mature oligodendrocytes that leads to a robust demyelination and profound activation of both astrocytes and microglia with regional heterogeneity between different white and gray matter regions. Although not suitable to study autoimmune mediated demyelination, this model is extremely helpful to elucidate basic cellular and molecular mechanisms during de- and particularly remyelination independently of interactions with peripheral immune cells. Phagocytosis and removal of damaged myelin seems to be one of the major roles of microglia in this model and it is well known that removal of myelin debris is a prerequisite of successful remyelination. Furthermore, microglia provide several signals that support remyelination. The role of astrocytes during de- and remyelination is not well defined. Both supportive and destructive functions have been suggested. Using the cuprizone model we could demonstrate that there is an important crosstalk between astrocytes and microglia. In this review we focus on the role of glial reactions and interaction in the cuprizone model. Advantages and limitations of as well as its potential therapeutic relevance for the human disease MS are critically discussed in comparison to other animal models.

BACKGROUND: It was investigated whether the European Group for Blood and Marrow Transplantation risk score, previously established for chronic myeloid leukemia, could be used to predict outcome after allogeneic hematopoietic stem cell transplantation (HSCT) for hematological disease in general. METHODS: Age of patient, disease stage, time interval from diagnosis to transplant, donor type, and donor‐recipient sex combination were used to establish a score from 0 to 7 points. Its validity was tested in 56,505 patients, 33,113 (58%) male, 23,392 female, median age 33 years (range, 0.5‐77 years), with an allogeneic HSCT for a hematological disorder between 1980 and 2005. RESULTS: Survival probability at 5 years decreased from 71% (95% confidence interval [CI], 69%‐73%) for risk score 0 for the whole cohort (75%, 95% CI, 72%‐78% for the most recent time cohort) to 24% (95% CI, 21%‐27% for risk score 6 and 7; 25%, 95% CI, 22%‐29% most recent cohort). Transplant‐related mortality increased from 15% (95% CI, 14%‐17%) for risk score 0 (11%, 95% CI, 9%‐13%, most recent cohort) to 47% with risk score 6 and 7 (95% CI, 44%‐50%) for the whole cohort (45%, 95% CI, 42%‐48%, most recent cohort). The risk score was predictive in all disease categories, over all time periods, and was not altered by transplant techniques. CONCLUSIONS: Five well‐defined pretransplant patient and donor characteristics give a reasonable risk estimate of allogeneic HSCT. This risk score can provide a basis for the decision between transplant and nontransplant strategies. Cancer 2009. © 2009 American Cancer Society.

Recent evidence suggests that astrocytes play an important role in regulating de- and remyelination in multiple sclerosis. The role of astrocytes is controversial, and both beneficial as well as detrimental effects are being discussed. We performed loss-of-function studies based on astrocyte depletion in a cuprizone-induced rodent model of demyelination. This led to strong astrogliosis accompanied by microgliosis and demyelination in C57BL/6 wild-type mice. Ablation of astrocytes in glial fibrillary acidic protein-thymidine kinase transgenic mice was associated with a failure of damaged myelin removal and a consecutive delay in remyelination. Despite oligodendrocyte death, myelin was still present, but ultrastructual investigations showed that the myelin structure was loosened and this damaged myelin did not protect axons. These alterations were associated with a decrease in microglial activation. Thus, our results show that astrocyte loss does not prevent myelin damage, but clearance of damaged myelin through recruitment of microglia is impaired. Further studies suggest that this process is regulated by the chemokine CXCL10. As a consequence of the delayed removal of myelin debris, remyelination and oligodendrocyte precursor cell proliferation were impaired. Experiments omitting the influence of myelin debris demonstrated an additional beneficial effect of astrocytes on oligodendrocyte regeneration during remyelination. In conclusion, these data demonstrate for the first time in vivo that astrocytes provide the signal environment that forms the basis for the recruitment of microglia to clear myelin debris, a process required for subsequent repair mechanisms. This is of great importance to understanding regenerative processes in demyelinating diseases such as multiple sclerosis.