Arianna Merlini

Plasma cells require autophagy for sustainable immunoglobulin production

The role of autophagy in plasma cells is unknown. Here we found notable autophagic activity in both differentiating and long-lived plasma cells and investigated its function through the use of mice with conditional deficiency in the essential autophagic molecule Atg5 in B cells. Atg5−/− differentiating plasma cells had a larger endoplasmic reticulum (ER) and more ER stress signaling than did their wild-type counterparts, which led to higher expression of the transcriptional repressor Blimp-1 and immunoglobulins and more antibody secretion. The enhanced immunoglobulin synthesis was associated with less intracellular ATP and more death of mutant plasma cells, which identified an unsuspected autophagy-dependent cytoprotective trade-off between immunoglobulin synthesis and viability. In vivo, mice with conditional deficiency in Atg5 in B cells had defective antibody responses, complete selection in the bone marrow for plasma cells that escaped Atg5 deletion and fewer antigen-specific long-lived bone marrow plasma cells than did wild-type mice, despite having normal germinal center responses. Thus, autophagy is specifically required for plasma cell homeostasis and long-lived humoral immunity.

iPSC-derived neural precursors exert a neuroprotective role in immune-mediated demyelination via the secretion of LIF

The possibility of generating neural stem/precursor cells (NPCs) from induced pluripotent stem cells (iPSCs) has opened a new avenue of research that might nurture bench-to-bedside translation of cell transplantation protocols in central nervous system myelin disorders. Here we show that mouse iPSC-derived NPCs (miPSC-NPCs)-when intrathecally transplanted after disease onset-ameliorate clinical and pathological features of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. Transplanted miPSC-NPCs exert the neuroprotective effect not through cell replacement, but through the secretion of leukaemia inhibitory factor that promotes survival, differentiation and the remyelination capacity of both endogenous oligodendrocyte precursors and mature oligodendrocytes. The early preservation of tissue integrity limits blood-brain barrier damage and central nervous system infiltration of blood-borne encephalitogenic leukocytes, ultimately responsible for demyelination and axonal damage. While proposing a novel mechanism of action, our results further expand the therapeutic potential of NPCs derived from iPSCs in myelin disorders.

Commonalities in immune modulation between mesenchymal stem cells (MSCs) and neural stem/precursor cells (NPCs)

Owing to their unique immunomodulatory properties, mesenchymal stem cells (MSCs) have been advocated as a potential therapy for numerous pathological conditions in which immune-mediated inflammatory reactions play a crucial role, such as autoimmune disorders, cerebrovascular diseases and tumours. Increasing evidence suggest that stem cells, other than MSCs, are also capable of immunomodulation. Neural stem/precursor cells (NPCs) have been among the first stem cells to show immunomodulatory properties and nowadays represent one the most studied and promising stem cell subtype in still uncurable acute and chronic inflammatory neurological disorders. Although the ontogeny of NPCs and MSCs greatly diverges, their immunomodulatory mechanisms are similar and are largely based on the bystander (paracrine) effect through membrane-bound and soluble mediators that influence the behavior of host immune cells. This observation suggests the existence of a core stem cell signature across different stem cell lineages and that shared signalling pathways between the stem cell niche and the inflammatory immune response likely mediate both NPC and MSC immunomodulatory effect.

Half-dose fingolimod for treating relapsing-remitting multiple sclerosis: Observational study.

Objectives: To investigate the efficacy and safety of fingolimod (FTY) 0.5 mg administered every other day (FTY-EOD) compared to every day (FTY-ED) in multiple sclerosis patients. Methods: Multicentre retrospective observational study. Clinical, laboratory and neuroimaging data were consecutively collected from 60 FTY-EOD and 63 FTY-ED patients. Baseline characteristics were compared using logistic regression. Efficacy in preventing occurrence of relapses and demyelinating lesions was tested using propensity score–adjusted Cox and linear regressions. Results: Weight was inversely associated with risk of switch to FTY-EOD because of any reason (odds ratio (OR) = 0.94, 95% confidence interval (95% CI) = 0.89–0.99, p = 0.026), and female sex and lower baseline lymphocyte count were positively associated with switch because of lymphopenia. Compared to FTY-ED patients, FTY-EOD patients were at higher risk of developing relapses (hazard ratio (HR) = 2.98, 95% CI = 1.07–8.27, p = 0.036) and either relapses or new magnetic resonance imaging (MRI) demyelinating lesions (combined outcome, HR = 2.07, 95% CI = 1.06–4.08, p = 0.034). Within FTY-EOD, treatment with natalizumab before FTY and lower age were positively associated with risk of developing relapses and combined outcome, respectively (HR = 25.71, 95% CI = 3.03–217.57, p = 0.002 and HR = 0.85, 95% CI = 0.77–0.96, p = 0.005). FTY-EOD was overall well tolerated. Conclusion: Disease reactivation was observed in a significant proportion of patients treated with FTY-EOD. Neurologists should be cautious when reducing FTY administration to every other day, especially in younger patients and those previously treated with natalizumab.

Neural precursor cell–secreted TGF-β2 redirects inflammatory monocyte-derived cells in CNS autoimmunity

In multiple sclerosis, the pathological interaction between autoreactive Th cells and mononuclear phagocytes in the CNS drives initiation and maintenance of chronic neuroinflammation. Here, we found that intrathecal transplantation of neural stem/precursor cells (NPCs) in mice with experimental autoimmune encephalomyelitis (EAE) impairs the accumulation of inflammatory monocyte-derived cells (MCs) in the CNS, leading to improved clinical outcome. Secretion of IL-23, IL-1, and TNF-&agr;, the cytokines required for terminal differentiation of Th cells, decreased in the CNS of NPC-treated mice, consequently inhibiting the induction of GM-CSF–producing pathogenic Th cells. In vivo and in vitro transcriptome analyses showed that NPC-secreted factors inhibit MC differentiation and activation, favoring the switch toward an antiinflammatory phenotype. Tgfb2–/– NPCs transplanted into EAE mice were ineffective in impairing MC accumulation within the CNS and failed to drive clinical improvement. Moreover, intrathecal delivery of TGF-&bgr;2 during the effector phase of EAE ameliorated disease severity. Taken together, these observations identify TGF-&bgr;2 as the crucial mediator of NPC immunomodulation. This study provides evidence that intrathecally transplanted NPCs interfere with the CNS-restricted inflammation of EAE by reprogramming infiltrating MCs into antiinflammatory myeloid cells via secretion of TGF-&bgr;2.

Neural Stem Cell Plasticity: Advantages in Therapy for the Injured Central Nervous System.

The physiological and pathological properties of the neural germinal stem cell niche have been well-studied in the past 30 years, mainly in animals and within given limits in humans, and knowledge is available for the cyto-architectonic structure, the cellular components, the timing of development and the energetic maintenance of the niche, as well as for the therapeutic potential and the cross talk between neural and immune cells. In recent years we have gained detailed understanding of the potentiality of neural stem cells (NSCs), although we are only beginning to understand their molecular, metabolic, and epigenetic profile in physiopathology and, further, more can be invested to measure quantitatively the activity of those cells, to model in vitro their therapeutic responses or to predict interactions in silico. Information in this direction has been put forward for other organs but is still limited in the complex and very less accessible context of the brain. A comprehensive understanding of the behavior of endogenous NSCs will help to tune or model them toward a desired response in order to treat complex neurodegenerative diseases. NSCs have the ability to modulate multiple cellular functions and exploiting their plasticity might make them into potent and versatile cellular drugs.

Falling too Fahr

Repeated falls are a frequent complaint of patients referring to neurology units [1]. The most prevalent causes are seizures, neurogenic and cardiac syncopes, vestibulopathies, and neurological disorders affecting gait and balance [2]. Nevertheless, other less common etiologies—e.g., cataplexy, drop attacks, hyperekplexia and tetany—may mimic neurologic or cardiovascular disturbances [3]. In this case report, we propose a rare yet relevant cause of recurring falls that should be kept in mind during differential diagnosis. A 19-year-old Asian woman presented to our emergency room for repeated falls characterized by stiffening of the four limbs. History-taking revealed that she had suffered since infancy from carpopedal spasms and sparse episodes of generalized muscle rigidity, which, however, had never been investigated. In the last weeks, an increase in the frequency of falls and spasms brought her to finally seek medical attention. During clinical examination, the patient suddenly fell backwards with a generalized tonic contraction that reverted within a minute, while a moderate hypertonus persisted over time. The diffuse cramps, repeated attacks of tonic spasms, and sustained hypertonus were all suggestive for generalized tetany. Consistently, Chvostek’s and Trousseau’s signs were found positive (Online Resource 1). Tetany is a condition of enhanced neuromuscular excitability, most frequently associated with electrolyte alterations [4]. Indeed, blood tests showed a remarkable hypocalcemia (1.13 mmol/l [reference interval 2.1–2.6]) with a prolonged corrected QT interval (0.470 s [r.i. B 0.450]) on electrocardiogram (ECG). To avoid further tetanic crises and cardiac complications, intravenous calcium gluconate was immediately started. Afterwards, brain-CT scan was performed, revealing widespread calcifications of grey–white matter junction, basal ganglia, thalamus, and dentate nuclei (Fig. 1). This pattern of striopallidal-dentate calcifications is commonly referred to as ‘Fahr’s disease’, a misnomer, and can be encountered in numerous chronic conditions, including persistent disturbances of phosphate/calcium metabolism [5]. This finding suggested that the tetanic crises of our patient were more likely the expression of an underlying chronic metabolic syndrome, rather than an isolated episode of hypocalcemia. Thus, we conducted an extended metabolic panel that revealed reduced serum 25-OH vitamin D (7.6 ng/ml [r.i. 10–68]) and ionized calcium (0.64 mmol/l [r.i. 1.18–1.3]) with increased phosphate (2.51 mmol/l [r.i. 0.8–1.5]) and parathyroid hormone (PTH, 349 pg/ml [r.i. 17.3–72.9]). Hypocalcemia, hyperphosphatemia, and high PTH are the hallmarks of pseudohypoparathyroidism (PHP), a rare A. Merlini, L. Peruzzotti-Jametti, and M. Bacigaluppi contributed equally to this work.

Assessing the role of innovative therapeutic paradigm on multiple sclerosis treatment response

Within the last decade, many changes have been made to the management of patients with multiple sclerosis (MS). The aim of our study was to investigate the global impact of all these changes on the diseases course.

Stem Cell-Based Therapies, Remyelination, and Repair Promotion in the Treatment of Multiple Sclerosis

The main challenges in the treatment of multiple sclerosis (MS) are eradication of autoimmunity and repair of the damaged central nervous system (CNS). Stem cells, due to their innate ability to replace damaged cells and cross-talk with the MS microenvironment, have been proposed as powerful tools to achieve at least one or both of such ambitious therapeutic goals. Autologous hematopoietic stem cell transplantation is indeed effective in severe forms of MS in halting inflammation but has no effect on CNS regeneration. On the other hand, preclinical studies with mesenchymal stem cells and neural precursor cells have shown that they exert neuroprotection but surprisingly only marginally through cell replacement and mostly via bystander immunomodulatory and trophic mechanisms.

Influence of experimental autoimmune encephalomyelitis on the localization and viability of neural stem cells after intrathecal transplantation

Introduction: Murine bone marrow mesenchymal stem cells (MSC) can adapt their therapeutic effects to specific microenvironments. In inflammatory conditions, in vitro MSC showed a modulation of genes referable to interferon gamma (IFNg) stimulation, likely involved in the enhancement of the therapeutic plasticity of MSC. The identity of proteins mediating this plasticity is not fully elucidated yet. This study aims at identifying the changes in the protein profile in MSC under IFNg stimulation that can explain the increased neuroprotective and immunomodulatory properties of MSC in inflammatory conditions. Materials and Methods: A Stable Isotope Labeling with Amino acids in cell Culture (SILAC)-based proteomic approach was used. The cells were labeled through the metabolic incorporation of isotopic 13C6Lysine and 13C6-Arginine or 12C6-Lysine and 12C6-Arginine into the proteins expressed by IFNg-primed or unprimed MSC, respectively. Protein identification and quantitation were performed by LC–ESIMS/MS with the Velos Elite Orbitrap mass spectrometer coupled to Mascot Distiller 2.3 interface. The changes in protein expression and signaling pathways represented in the two conditions were analyzed with the Ingenuity Pathways Analysis software. Results: Analysis of the IFNg-primed MSC lysates highlighted an activation of the antigen presentation process, lipid metabolism and response to oxidative stress. Protein synthesis, cell cycle regulation, endoplasmic reticulum stress, along with IFNg-signaling, were also perturbed. IFNg-primed MSC conditioned medium showed an increased level of proteins involved in the regulation of cell–cell and cell–matrix interactions, immunomodulatory and neuroprotective proteins and proteins involved in cholesterol trafficking (analysis in progress). Furthermore, preliminary data suggest that extracellular membrane vesicles released byMSC could shuttle relevantmolecules to mediate, at least partially, the immunomodulatory effect of MSC on activated T cells. Discussion and Conclusions: In response to inflammatory stimulation, MSC are able to change profoundly the protein profile and activate specific metabolic and signaling pathways that likely lead to the enhancement of their therapeutic effects. The identification of new regulatory molecules involved in the therapeutic plasticity of MSC paves the way to the study of new therapeutic approaches to treat autoimmune and neurodegenerative diseases.