Human peripheral blood mononuclear cells exhibit heterogeneous CD52 expression levels and show differential sensitivity to alemtuzumab mediated cytolysis

Implementation of the Methyl-Seq platform to identify tissue- and sex-specific DNA methylation differences in the rat epigenome

Epigenomic annotations for the rat lag far behind those of human and mouse, despite the rat's immense utility in pharmacological and behavioral studies and the need to understand their epigenetic mechanisms. We have designed a targeted-enrichment method followed by next-generation sequencing (Methyl-Seq) to identify DNA methylation (DNAm) signatures across the rat genome. The design reflected an attempt to create a more comprehensive investigation of the rat epigenome, as it included promoters, CpG islands, and island shores of all RefSeq genes. In this study, we implemented the rat Methyl-Seq platform and tested its ability to distinguish differentially methylated regions (DMRs) among three different tissue types, three distinct brain regions, and, in the hippocampus, between males and females. These comparisons yielded DNAm differences of differing magnitudes, many of which were independently validated by bisulfite pyrosequencing, including autosomal regions that were predicted to show the least degree of difference in DNAm between males and females. Quantitative reverse transcription PCR revealed that most genes associated with the DMRs showed tissue-, brain region-, and sex-specific differences in expression. In particular, we found evidence for sex-specific DNAm and expression differences at Tubb6, Lrrn2, Tex26, and Sox5l1, all of which play important roles in neurodevelopment and have been implicated in studies examining sex differences. Our results demonstrate the utility of the rat Methyl-Seq platform and suggest the presence of DNAm differences between the male and female hippocampus. The rat Methyl-Seq has the potential to provide epigenomic insights into pharmacological and behavioral studies performed in the rat.

Phase 1 Trials of Gatralimab, a Next-Generation Humanized Anti-CD52 Monoclonal Antibody, in Participants with Progressive Multiple Sclerosis

INTRODUCTION

Lymphocyte depletion via anti-CD52 monoclonal antibody (mAb) therapy is an effective treatment strategy for relapsing-remitting multiple sclerosis (MS) but is associated with infusion/injection-associated reactions (IARs) and autoimmune-related adverse events (AEs). Gatralimab is a next-generation humanized anti-CD52 mAb.

METHODS

Two first-in-human trials were conducted in participants with progressive MS to assess the pharmacodynamics, pharmacokinetics, and safety of gatralimab administered via subcutaneous (SC) and intravenous (IV) routes, and to determine the effect of different comedication regimes on IARs to SC gatralimab. A Phase 1 trial (NCT02282826) included double-blind, placebo-controlled sequential ascending single IV (1, 3.5, and 12 mg) and SC (12, 36, and 60 mg) dose groups. A Phase 1b trial (NCT02977533) involved five groups who received SC gatralimab (36, 48, or 60 mg) and different comedications. A long-term safety (LTS) study (NCT02313285) examined safety and pharmacodynamics over 4 years.

RESULTS

Gatralimab produced depletion of lymphocytes (dose-dependently) and CD4+ regulatory T cells, with partial repopulation to normal values by approximately 12 months. Peak serum gatralimab concentrations followed dose-proportionality and were delayed by 6.0-7.5 days following SC administration. Treatment-emergent AEs, including IARs, were reported for most participants but were generally of mild or moderate severity, and treatment-emergent serious AEs were mostly MS-related. Methylprednisolone and antihistamine comedications were associated with reduced incidence of fevers and skin and subcutaneous tissue AEs, respectively. During the LTS study, one participant (3.0%) experienced an autoimmune-related AE (Basedow's disease), and subsequently died from pulmonary sepsis deemed unrelated to gatralimab by the investigator.

CONCLUSIONS

These data show that gatralimab achieves the desired pharmacodynamic effect of lymphocyte depletion followed by repopulation, and has an acceptable safety profile, including low risk of non-MS autoimmunity. Although gatralimab is no longer in development for MS, insights from these trials may inform the development of comedication regimes of future anti-CD52 mAbs and subcutaneous formulations of other lymphocyte-depleting mAbs.

TRIAL REGISTRATION

NCT02282826, NCT02977533, NCT02313285.

Hemophagocytic lymphohistiocytosis: current treatment advances, emerging targeted therapy and underlying mechanisms

Hemophagocytic lymphohistiocytosis (HLH) is a rapidly progressing, life-threatening syndrome characterized by excessive immune activation, often presenting as a complex cytokine storm. This hyperactive immune response can lead to multi-organ failure and systemic damage, resulting in an extremely short survival period if left untreated. Over the past decades, although HLH has garnered increasing attention from researchers, there have been few advancements in its treatment. The cytokine storm plays a crucial role in the treatment of HLH. Investigating the detailed mechanisms behind cytokine storms offers insights into targeted therapeutic approaches, potentially aiding in early intervention and improving the clinical outcome of HLH patients. To date, there is only one targeted therapy, emapalumab targeting interferon-γ, that has gained approval for primary HLH. This review aims to summarize the current treatment advances, emerging targeted therapeutics and underlying mechanisms of HLH, highlighting its newly discovered targets potentially involved in cytokine storms, which are expected to drive the development of novel treatments and offer fresh perspectives for future studies. Besides, multi-targeted combination therapy may be essential for disease control, but further trials are required to determine the optimal treatment mode for HLH.

Cis-interaction between CD52 and T cell receptor complex interferes with CD4+ T cell activation in acute decompensation of cirrhosis

BACKGROUND

Immune dysfunction contributes to a high rate of infection in patients with acute decompensation of cirrhosis. CD52 is a glycoprotein prominently expressed in lymphocytes. Immune regulation by CD52 may be involved in adaptive immune dysfunction in cirrhosis. This study aimed to investigate the function of CD52 on CD4+ T cells on the blood of patients with acute decompensation of cirrhosis.

METHODS

The expression of CD52 in the peripheral blood lymphocytes of 49 patients with cirrhosis was investigated using flow cytometry and transcriptomics. Potential cis-membrane ligands of CD52 were discovered via proximity labelling followed by proteomics. The function of CD52 on antigen-specific activation of CD4+ T cells was examined using flow cytometry in CD52 CRISPR-Cas9 knockout primary T cells.

FINDINGS

CD52 expression was elevated in CD4+ T cells in acute decompensation of cirrhosis, and this elevation was correlated with increased disease severity and mortality. Components of the T cell receptor complex including TCRβ, CD3γ and CD3ε were identified and validated as cis-membrane ligands of CD52. Knockout of CD52 promoted antigen-specific activation, proliferation, and pro-inflammatory cytokine secretion.

INTERPRETATION

Membrane bound CD52 demonstrated cis-interaction with the T cell receptor and served as a dynamic regulator of antigen-specific activation of CD4+ T cells. The upregulation of CD52 in the periphery of acute decompensation of cirrhosis hinders the recognition of the T cell receptor by MHC, contributing to impaired T cell function. The development of an alternative anti-CD52 antibody is required to restore T cell function and prevent infections in cirrhosis.

FUNDING

This study was supported by the NIHR Imperial Biomedical Research Centre, Institute for Translational Medicine and Therapeutics (P74713), Wellcome Trust (218304/Z/19/Z), and Medical Research Council (MR/X009904/1 and MR/R014019/1).

Impact of alemtuzumab-mediated lymphocyte depletion on SIV reservoir establishment and persistence

Persistence of the rebound-competent viral reservoir (RCVR) within the CD4+ T cell compartment of people living with HIV remains a major barrier to HIV cure. Here, we determined the effects of the pan-lymphocyte-depleting monoclonal antibody (mAb) alemtuzumab on the RCVR in SIVmac239-infected rhesus macaques (RM) receiving antiretroviral therapy (ART). Alemtuzumab administered during chronic ART or at the time of ART initiation induced >95% depletion of circulating CD4+ T cells in peripheral blood and substantial CD4+ T cell depletion in lymph nodes. However, treatment was followed by proliferation and reconstitution of CD4+ T cells in blood, and despite ongoing ART, levels of cell-associated SIV DNA in blood and lymphoid tissues were not substantially different between alemtuzumab-treated and control RM after immune cell reconstitution, irrespective of the time of alemtuzumab treatment. Upon ART cessation, 19 of 22 alemtuzumab-treated RM and 13 of 13 controls rebounded with no difference in the time to rebound between treatment groups. Time to rebound and reactivation rate was associated with plasma viral loads (pVLs) at time of ART initiation, suggesting lymphocyte depletion had no durable impact on the RCVR. However, 3 alemtuzumab-treated RM that had lowest levels of pre-ART viremia, failed to rebound after ART withdrawal, in contrast to controls with similar levels of SIV replication. These observations suggest that alemtuzumab therapy has little to no ability to reduce well-established RCVRs but may facilitate RCVR destabilization when pre-ART virus levels are particularly low.

Early recovery of natural killer cells post T-cell depleted allogeneic stem cell transplantation using alemtuzumab "in the bag"

BACKGROUND

Allogeneic stem cell transplantation (SCT) is a critical therapy for haematological malignancy but may lead to acute and chronic graft versus host disease (GvHD). T-cell depletion with alemtuzumab, either in vivo or ex vivo, reduces the incidence of GvHD but is a risk factor for disease relapse and poor immune reconstitution. Natural killer (NK) cells are the first lymphocytes to recover. Classical NK cells make up >90% of the normal circulating population and can directly kill neoplastic or virally infected cells while the regulatory subset makes up <10%, secretes cytokines and is not cytotoxic. The recovery and balance of these subsets post SCT remains controversial, with most studies analysing patients who received unmanipulated grafts and in vivo immunosuppression.

OBJECTIVE

The aim was to assess the early recovery of NK cells in 18 consecutive patients receiving ex vivo T-cell depleted SCT and to compare the results to 25 individuals receiving haploidentical non-T cell depleted grafts.

METHODS

All patients received myeloablative conditioning. After stem cell collection, the stem cells of the T cell depleted group were treated "in the bag" with alemtuzumab (CAMPATH 1H) at a concentration of 1mg/108 mononuclear cells and thereafter immediately infused. For those receiving non-T cell depleted grafts, GvHD prophylaxis was with post infusion therapeutic doses of cyclophosphamide. Blood samples were collected at days 21, 28 and 90. Complete blood counts were performed on an automated analyser while lymphocyte and NK subsets were examined using multiparameter flowcytometry. NK cells were defined as lymphocytes which were CD3-/CD56+. The classical subset was recognised as CD56dim/CD16+ while the regulatory population as CD56bright/CD16-. The results for both transplant types were compared at all time points using SPSS v8 statistical software.

RESULTS

The recovery of lymphocytes was slow in both groups. Those receiving non-T cell depleted grafts had significantly higher T cell counts at day 21 and 28 when compared to the T cell depleted group (P < 0.05). In contrast, NK cells in the ex vivo T-cell depleted patients recovered rapidly and by day 21 was no different to normal (p > 0.05), while the non-T cell depleted group had significantly decreased numbers (p < 0.001), only recovering at day 90. Both groups had abnormal NK cell subset ratios with significantly elevated percentages of regulatory cells (p < 0.05). However, significant differences were observed between the two groups with those receiving T cell depleted grafts having lower percentages of regulatory cells as well as higher numbers of classical NK cells at day 21 and 28 (p < 0.01).

CONCLUSION

This study of ex vivo T-cell depleted SCT's demonstrates that NK cells recover quicker when compared to those receiving unfractionated grafts. These results may have implications for GvHD and the GvL effect which warrants further study.

Allogeneic Hematopoietic cell Transplantation Using Alemtuzumab in Asian Patients with Inborn Errors of Immunity

Alemtuzumab is used with reduced-toxicity conditioning (RTC) in allogeneic hematopoietic cell transplantation (HCT), demonstrating efficacy and feasibility for patients with inborn errors of immunity (IEI) in Western countries; however, the clinical experience in Asian patients with IEI is limited. We retrospectively analyzed patients with IEI who underwent the first allogeneic HCT with alemtuzumab combined with RTC regimens in Japan. A total of 19 patients were included and followed up for a median of 18 months. The donors were haploidentical parents (n = 10), matched siblings (n = 2), and unrelated bone marrow donors (n = 7). Most patients received RTC regimens containing fludarabine and busulfan and were treated with 0.8 mg/kg alemtuzumab with intermediate timing. Eighteen patients survived and achieved stable engraftment, and no grade 3-4 acute graft-versus-host disease was observed. Viral infections were observed in 11 patients (58%) and 6 of them presented symptomatic. The median CD4+ T cell count was low at 6 months (241/µL) but improved at 1 year (577/µL) after HCT. Whole blood cells continued to exhibit > 80% donor type in most cases; however, 3/10 patients exhibited poor donor chimerism only among T cells and also showed undetectable levels of T-cell receptor recombination excision circles (TRECs) at 1 year post-HCT. This study demonstrated the efficacy and safety of alemtuzumab; however, patients frequently developed viral infections and slow reconstitution or low donor chimerism in T cells, emphasizing the importance of monitoring viral status and T-cell-specific chimerism. (238 < 250 words).

Neonatal immune cells have heightened responses following in-utero exposure to chorioamnionitis or COVID-19

BACKGROUND

Chorioamnionitis alters neonatal immune responses. Gestational COVID-19 infection is associated with adverse pregnancy outcomes, but its impact on neonatal immunity is unclear. We hypothesized that gestational COVID-19 exposure would result in exaggerated neonatal immune responses, similar to chorioamnionitis-exposed neonates.

METHODS

Term umbilical cord blood mononuclear cells (CBMCs) were isolated from neonates exposed to chorioamnionitis, gestational COVID-19 or unexposed controls. CBMCs were cultured and stimulated with heat-killed Escherichia coli, Streptococcus agalactiae or Staphylococcus epidermidis. A multiplexed protein assay was used to measure cytokine levels in cell culture supernatants and flow cytometry was used to evaluate cellular-level cytokine expression.

RESULTS

Both chorioamnionitis-exposed and COVID-19 exposed CBMCs demonstrated upregulation of IL-1β and IL-6 compared to unexposed CBMCs, while only COVID-19 exposure resulted in IL-8 upregulation. There were no differences between chorioamnionitis-exposed and COVID-19 exposed CBMCs when these groups were directly compared. Flow cytometry demonstrated immune cell subset specific differences in cytokine expression between the exposure groups.

CONCLUSION

The fetal/neonatal response to maternal inflammation differed based on immune cell subset and etiology of inflammation, but the global neonatal cytokine responses were similar between exposure groups. This suggests that targeting perinatal inflammation rather than the specific etiology may be a possible therapeutic approach.

IMPACT

Neonatal immune cells have similar pathogen-associated global cytokine responses, but different cell-level immune responses, following in-utero exposure to chorioamnionitis or COVID-19. This is the first study to directly compare immune responses between neonates exposed to chorioamnionitis and COVID-19. This suggests that the fetal/neonatal cellular response to perinatal inflammation differs based on the etiology and severity of maternal inflammation, but still results in a similar overall inflammatory profile regardless of the cause of perinatal inflammation.

CD52 knockdown inhibits aerobic glycolysis and malignant behavior of NSCLC cells through AKT signaling pathway

CD52 is an important functional regulator involved in the development of human cancer. In this study, the clinical significance and biological function of CD52 in the malignant behavior of non-small cell lung cancer (NSCLC) were explored. In this study, immunohistochemical (IHC) staining was performed to determine the expression pattern of CD52 in NSCLC. Loss of function assays were used to evaluate the biological functions of CD52 in NSCLC cells in vitro and in vivo. Our data indicated that the expression of CD52 was significantly elevated in NSCLC and correlated with the patient prognosis. Functionally, downregulation of CD52 expression significantly suppressed the proliferation, migration, aerobic glycolysis and tumorigenesis of NSCLC cells. Moreover, CD52 regulated aerobic glycolysis of NSCLC cells through the AKT pathway. Furthermore, aerobic glycolysis induced by 2-DG inhibited the proliferation of NSCLC cells. In conclusion, CD52 knockdown inhibited aerobic glycolysis and malignant behavior of NSCLC cells through AKT signaling pathway, which may be employed in an alternative therapeutic target for NSCLC.

Therapeutic tactics for targeting B lymphocytes in autoimmunity and cancer

B lymphocytes have become a very popular therapeutic target in a number of autoimmune indications due to their newly appreciated roles, and approachability, in these diseases. Many of the therapies now applied in autoimmunity were initially developed to deplete malignant B cells. These strategies have also been found to benefit patients suffering from such autoimmune diseases as multiple sclerosis, type I diabetes, systemic lupus erythematosus, and rheumatoid arthritis, to name a few. These observations have supported the expansion of research addressing the mechanistic contributions of B cells in these diseases, as well as blossoming of therapeutics that target them. This review seeks to summarize cutting-edge modalities for targeting B cells, including monoclonal antibodies, bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor-T cells, and small molecule inhibitors. Efforts to refine B-cell targeted therapy to eliminate only pathogenic autoreactive cells will be addressed as well as the potential for future B-cell-based cellular therapeutics. Finally, we also address approaches that seek to silence B-cell function without depletion.

Disease Modifying Strategies in Multiple Sclerosis: New Rays of Hope to Combat Disability?

Multiple sclerosis (MS) is the most prevalent chronic autoimmune inflammatory- demyelinating disorder of the central nervous system (CNS). It usually begins in young adulthood, mainly between the second and fourth decades of life. Usually, the clinical course is characterized by the involvement of multiple CNS functional systems and by different, often overlapping phenotypes. In the last decades, remarkable results have been achieved in the treatment of MS, particularly in the relapsing- remitting (RRMS) form, thus improving the long-term outcome for many patients. As deeper knowledge of MS pathogenesis and respective molecular targets keeps growing, nowadays, several lines of disease-modifying treatments (DMT) are available, an impressive change compared to the relative poverty of options available in the past. Current MS management by DMTs is aimed at reducing relapse frequency, ameliorating symptoms, and preventing clinical disability and progression. Notwithstanding the relevant increase in pharmacological options for the management of RRMS, research is now increasingly pointing to identify new molecules with high efficacy, particularly in progressive forms. Hence, future efforts should be concentrated on achieving a more extensive, if not exhaustive, understanding of the pathogenetic mechanisms underlying this phase of the disease in order to characterize novel molecules for therapeutic intervention. The purpose of this review is to provide a compact overview of the numerous currently approved treatments and future innovative approaches, including neuroprotective treatments as anti-LINGO-1 monoclonal antibody and cell therapies, for effective and safe management of MS, potentially leading to a cure for this disease.

Reconsidering the route of drug delivery in refractory multiple sclerosis: Toward a more effective drug accumulation in the central nervous system

Multiple sclerosis is a chronic demyelinating disease with different disease phenotypes. The current FDA-approved disease-modifying therapeutics (DMTs) cannot cure the disease, but only alleviate the disease progression. While the majority of patients respond well to treatment, some of them are suffering from rapid progression. Current drug delivery strategies include the oral, intravenous, subdermal, and intramuscular routes, so these drugs are delivered systemically, which is appropriate when the therapeutic targets are peripheral. However, the potential benefits may be diminished when these targets sequester behind the barriers of the central nervous system. Moreover, systemic drug administration is plagued with adverse effects, sometimes severe. In this context, it is prudent to consider other drug delivery strategies improving their accumulation in the brain, thus providing better prospects for patients with rapidly progressing disease course. These targeted drug delivery strategies may also reduce the severity of systemic adverse effects. Here, we discuss the possibilities and indications for reconsideration of drug delivery routes (especially for those "non-responding" patients) and the search for alternative drug delivery strategies. More targeted drug delivery strategies sometimes require quite invasive procedures, but the potential therapeutic benefits and reduction of adverse effects could outweigh the risks. We characterized the major FDA-approved DMTs focusing on their therapeutic mechanism and the potential benefits of improving the accumulation of these drugs in the brain.

Safety and efficacy with alemtuzumab over 13 years in relapsing-remitting multiple sclerosis: final results from the open-label TOPAZ study

Background and objectives

Alemtuzumab demonstrated superior efficacy versus subcutaneous interferon (IFN) beta-1a in participants with relapsing-remitting multiple sclerosis in the 2-year CARE-MS I and II trials. Efficacy was maintained in the 4-year CARE-MS extension, during which alemtuzumab-treated participants ('alemtuzumab-only') could receive additional courses upon disease activity, and IFN-treated participants switched to alemtuzumab ('IFN-alemtuzumab'). Participants who completed the CARE-MS extension could enroll in the open-label TOPAZ study which assessed safety and efficacy for 5-7 years (11-13 years after alemtuzumab/IFN initiation).

Methods

Participants received additional alemtuzumab courses as needed. Assessments included adverse events (AEs; primary outcome), annualized relapse rate (ARR), 6-month confirmed disability worsening [CDW; ⩾1.0-point Expanded Disability Status Scale (EDSS) score increase or ⩾1.5 if baseline EDSS = 0], and 6-month confirmed disease improvement [CDI; >1.0-point EDSS decrease (baseline score ⩾2.0)].

Results

43.5% of alemtuzumab-only participants from CARE-MS II and 54.2% from CARE-MS I received no additional alemtuzumab courses; 30.0% and 20.9%, respectively, received one additional course (the median). Incidences of AEs, including thyroid AEs and infections, declined over time. The safety profile of alemtuzumab was similar for participants who received zero, one, or two additional courses. For CARE-MS II participants, who had inadequate response to previous treatment, ARR remained low during Years 3-13 for the alemtuzumab-only [0.17; 95% confidence interval (CI) 0.15-0.20] and IFN-alemtuzumab (0.14; 0.11-0.17) groups. At Year 11, the proportions of participants who were either free from CDW or who had CDI were higher in the alemtuzumab-only group (58% and 49%, respectively) than in the IFN-alemtuzumab group (51% and 37%). For CARE-MS I participants, who were previously treatment-naïve, clinical outcomes remained improved, and no between-group differences were apparent.

Conclusion

Safety risks associated with alemtuzumab treatment declined over time. Clinical benefits were maintained up to 11-13 years, and most participants did not require more than one additional course.

Clinicaltrialsgov identifiers

NCT00530348; NCT00548405; NCT00930553; NCT02255656.

Immune reconstitution following alemtuzumab therapy is characterized by exhausted T cells, increased regulatory control of proinflammatory T cells and reduced B cell control

Alemtuzumab is a monoclonal antibody targeting CD52 on the surface of immune cells, approved for the treatment of active relapsing-remitting multiple sclerosis (RRMS). The purpose of this study was to analyze the repopulation of peripheral lymphocytes following alemtuzumab-induced lymphocyte depletion and investigate associations with disease activity and development of secondary autoimmunity. For this, blood samples were collected two years after initiation of alemtuzumab treatment and lymphocytes were subjected to a comprehensive flow cytometry analysis. Included in the study were 40 patients treated with alemtuzumab and 40 treatment-naïve patients with RRMS. Disease activity and development of secondary autoimmune disease was evaluated after three years of treatment. Our study confirms that alemtuzumab treatment profoundly alters the circulating lymphocyte phenotype and describes a reconstituted immune system characterized by T cell activation/exhaustion, an increased regulatory control of IL-17 producing effector T cells and CD20+ T cells, and a reduced control of B cells. There were no obvious associations between immune cell subsets and disease activity or development of secondary autoimmune disease during treatment with alemtuzumab. Our results indicate that the reconstituted immune response is skewed towards a more effective regulatory control of MS-associated proinflammatory T cell responses. Also, the enlarged pool of naïve B cells together with the apparent decrease in control of B cell activity may explain why alemtuzumab-treated patients retain the ability to mount a humoral immune response towards new antigens.

Alemtuzumab for multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is an autoimmune, T-cell-dependent, inflammatory, demyelinating disease of the central nervous system, with an unpredictable course. Current MS therapies focus on treating and preventing exacerbations, and avoiding the progression of disability. At present, there is no treatment that is capable of safely and effectively reaching these objectives. Clinical trials suggest that alemtuzumab, a humanized monoclonal antibody, could be a promising option for MS.

OBJECTIVES

To evaluate the benefits and harms of alemtuzumab alone or associated with other treatments in people with any form of MS.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 21 June 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in adults with any subtype of MS comparing alemtuzumab alone or associated with other medications versus placebo; another active drug; or alemtuzumab in another dose, regimen, or duration.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our co-primary outcomes were 1. relapse-free survival, 2. sustained disease progression, and 3. number of participants experiencing at least one adverse event. Our secondary outcomes were 4. participants free of clinical disability, 5. quality of life, 6. change in disability, 7. fatigue, 8. new or enlarging lesions on resonance imaging, and 9. dropouts. We used GRADE to assess certainty of evidence for each outcome.

MAIN RESULTS

We included three RCTs (1713 participants) comparing intravenous alemtuzumab versus subcutaneous interferon beta-1a for relapsing-remitting MS. Participants were treatment-naive (two studies) or had experienced at least one relapse after interferon or glatiramer (one study). Alemtuzumab was given at doses of 12 mg/day or 24 mg/day for five days at months 0 and 12, or 24 mg/day for three days at months 12 and 24. Participants in the interferon beta-1a group received 44 μg three times weekly. Alemtuzumab 12 mg: 1. may improve relapse-free survival at 36 months (hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.18 to 0.53; 1 study, 221 participants; low-certainty evidence); 2. may improve sustained disease progression-free survival at 36 months (HR 0.25, 95% CI 0.11 to 0.56; 1 study, 223 participants; low-certainty evidence); 3. may make little to no difference on the proportion of participants with at least one adverse event at 36 months (risk ratio [RR] 1.00, 95% CI 0.98 to 1.02; 1 study, 224 participants; low-certainty evidence), although the proportion of participants with at least one adverse event was high with both drugs; 4. may slightly reduce disability at 36 months (mean difference [MD] -0.70, 95% CI -1.04 to -0.36; 1 study, 223 participants; low-certainty evidence). The evidence is very uncertain regarding the risk of dropouts at 36 months (RR 0.81, 95% CI 0.57 to 1.14; 1 study, 224 participants; very low-certainty evidence). Alemtuzumab 24 mg: 1. may improve relapse-free survival at 36 months (HR 0.21, 95% CI 0.11 to 0.40; 1 study, 221 participants; low-certainty evidence); 2. may improve sustained disease progression-free survival at 36 months (HR 0.33, 95% CI 0.16 to 0.69; 1 study, 221 participants; low-certainty evidence); 3. may make little to no difference on the proportion of participants with at least one adverse event at 36 months (RR 0.99, 95% CI 0.97 to 1.02; 1 study, 215 participants; low-certainty evidence), although the proportion of participants with at least one adverse event was high with both drugs; 4. may slightly reduce disability at 36 months (MD -0.83, 95% CI -1.16 to -0.50; 1 study, 221 participants; low-certainty evidence); 5. may reduce the risk of dropouts at 36 months (RR 0.08, 95% CI 0.01 to 0.57; 1 study, 215 participants; low-certainty evidence). For quality of life, fatigue, and participants free of clinical disease activity, the studies either did not consider these outcomes or they used different measuring tools to those planned in this review.

AUTHORS' CONCLUSIONS

Compared with interferon beta-1a, alemtuzumab may improve relapse-free survival and sustained disease progression-free survival, and make little to no difference on the proportion of participants with at least one adverse event for people with relapsing-remitting MS at 36 months. The certainty of the evidence for these results was very low to low.

A real-life study of alemtuzumab in persons with multiple sclerosis: Kuwait's experience

BACKGROUND

Alemtuzumab, a humanized anti-CD52 monoclonal antibody, has been approved as a treatment in persons with active relapsing-remitting multiple sclerosis (RRMS). Real-world data in middle east is very limited. We aimed to evaluate the effectiveness and safety of alemtuzumab in a real-world clinical setting.

METHODS

This observational, registry based study assessed persons with multiple sclerosis (PwMS) who were treated with alemtuzumab and completed at least follow up one year after second course. Baseline clinical and radiological characteristics within one year prior to alemtuzumab initiation were collected. The relapse rate, disability measures, radiological activity and adverse events at last follow-up visits were assessed.

RESULTS

Data of seventy-three persons with multiple sclerosis (MS) was analyzed, of which 53 (72.6%) were females. Mean age and mean disease duration were 34.25 ± 7.62 and 9.23 ± 6.20 years respectively. Alemtuzumab was started in 32 (43.8%) naïve patients due to highly active disease and in 25 (34.2%) (PwMS) who were on prior therapies and  in 16 (22%) patients due to adverse events on prior medications. Mean follow-up period was 4 ± 1.67 years. In the last follow-up visits, most of our cohort was relapse free (79.5% vs. 17.8%; p < 0.001) compared to baseline before alemtuzumab treatment while mean EDSS score was reduced (2.21 ± 2.15 vs. 2.41 ± 1.85; p < 0.059). The proportion of PwMS who had MRI activity (new T2/ Gd-enhancing) lesions were significantly reduced compared to baseline (15.1% vs. 82.2%; p < 0.001). NEDA-3 was achieved in 57.5% of (PwMS). NEDA-3 was significantly better in naïve patients (78% versus. 41.5%; p < 0.002) and in patients with disease duration < 5 years, (82.6% v 43.2%; p < 0.002). Several adverse events such as infusion reactions (75.3%), autoimmune thyroiditis (16.4%) and glomerulonephritis (2.7%) were reported.

CONCLUSION

The effectiveness and safety profile of alemtuzumab in this cohort were consistent with data of clinical trials. Early initiation of Alemtuzumab is associated with favorable outcome.

Adoptive T-cell therapy targeting Epstein-Barr virus as a treatment for multiple sclerosis

Emergence of a definitive link between Epstein-Barr virus (EBV) and multiple sclerosis has provided an impetus to develop immune-based therapies to target EBV-infected B cells. Initial studies with autologous EBV-specific T-cell therapy demonstrated that this therapy is safe with minimal side effects and more importantly multiple patients showed both symptomatic and objective neurological improvements including improved quality of life, reduction of fatigue and reduced intrathecal IgG production. These observations have been successfully extended to an 'off-the-shelf' allogeneic EBV-specific T-cell therapy manufactured using peripheral blood lymphocytes of healthy seropositive individuals. This adoptive immunotherapy has also been shown to be safe with encouraging clinical responses. Allogeneic EBV T-cell therapy overcomes some of the limitations of autologous therapy and can be rapidly delivered to patients with improved therapeutic potential.

Risk of cervical pre-cancer and cancer in women with multiple sclerosis exposed to high efficacy disease modifying therapies

There is a growing need to better understand the risk of malignancy in the multiple sclerosis (MS) population, particularly given the relatively recent and widespread introduction of immunomodulating disease modifying therapies (DMTs). Multiple sclerosis disproportionately affects women, and the risk of gynecological malignancies, specifically cervical pre-cancer and cancer, are of particular concern. The causal relationship between persistent human papillomavirus (HPV) infection and cervical cancer has been definitively established. To date, there is limited data on the effect of MS DMTs on the risk of persistent HPV infection and subsequent progression to cervical pre-cancer and cancer. This review evaluates the risk of cervical pre-cancer and cancer in women with MS, including the risk conferred by DMTs. We examine additional factors, specific to the MS population, that alter the risk of developing cervical cancer including participation in HPV vaccination and cervical screening programs.

CD52 and OXPHOS-potential targets in ibrutinib-treated mantle cell lymphoma

Altered features of tumor cells acquired across therapy can result in the survival of treatment-resistant clones that may cause minimal residual disease (MRD). Despite the efficacy of ibrutinib in treating relapsed/refractory mantle cell lymphoma, the obstacle of residual cells contributes to relapses of this mature B-cell neoplasm, and the disease remains incurable. RNA-seq analysis of an ibrutinib-sensitive mantle cell lymphoma cell line following ibrutinib incubation of up to 4 d, corroborated our previously postulated resistance mechanism of a metabolic switch to reliance on oxidative phosphorylation (OXPHOS) in surviving cells. Besides, we had shown that treatment-persisting cells were characterized by increased CD52 expression. Therefore, we hypothesized that combining ibrutinib with another agent targeting these potential escape mechanisms could minimize the risk of survival of ibrutinib-resistant cells. Concomitant use of ibrutinib with OXPHOS-inhibitor IACS-010759 increased toxicity compared to ibrutinib alone. Targeting CD52 was even more efficient, as addition of CD52 mAb in combination with human serum following ibrutinib pretreatment led to rapid complement-dependent-cytotoxicity in an ibrutinib-sensitive cell line. In primary mantle cell lymphoma cells, a higher toxic effect with CD52 mAb was obtained, when cells were pretreated with ibrutinib, but only in an ibrutinib-sensitive cohort. Given the challenge of treating multi-resistant mantle cell lymphoma patients, this work highlights the potential use of anti-CD52 therapy as consolidation after ibrutinib treatment in patients who responded to the BTK inhibitor to achieve MRD negativity and prolong progression-free survival.

Logic-gated antibody pairs that selectively act on cells co-expressing two antigens

The use of therapeutic monoclonal antibodies is constrained because single antigen targets often do not provide sufficient selectivity to distinguish diseased from healthy tissues. We present HexElect®, an approach to enhance the functional selectivity of therapeutic antibodies by making their activity dependent on clustering after binding to two different antigens expressed on the same target cell. lmmunoglobulin G (lgG)-mediated clustering of membrane receptors naturally occurs on cell surfaces to trigger complement- or cell-mediated effector functions or to initiate intracellular signaling. We engineer the Fc domains of two different lgG antibodies to suppress their individual homo-oligomerization while promoting their pairwise hetero-oligomerization after binding co-expressed antigens. We show that recruitment of complement component C1q to these hetero-oligomers leads to clustering-dependent activation of effector functions such as complement mediated killing of target cells or activation of cell surface receptors. HexElect allows selective antibody activity on target cells expressing unique, potentially unexplored combinations of surface antigens.

The genealogy, methodology, similarities and differences of immune reconstitution therapies for multiple sclerosis and neuromyelitis optica

Immune reconstitution therapies (IRTs) are a type of short course procedure or pharmaceutical agent within the MS pharmacopeia. They emanate from oncology and induce transient incomplete lympho-ablation with or without myelo-ablation, resulting in potential prolonged immunomodulation. Thus, they provide significant prophylaxis from disease activity without retreatment. Modern IRT for autoimmunity encompasses a heterogeneous group of pulsed lympho- and non-myelo-ablative treatments designed to re-boot the adaptive immune system in a quasi-permanent manner - a re-induction of ontogeny. IRT is the extensive debulking of an auto-aggressive immune system to attempt to reach the Holy Grail of immune tolerance. This incomplete yet significant lympho-ablation induces lymphoproliferation, reduces pathogenic clonal cells, causes thymopoiesis and results in the induction of immune tolerance. Lympho-ablation with immune reconstitution can result in minimal residual autoimmunity. There is a resetting of the immune thermostat - i.e., the immunostat. IRTs have the potential to provide prolonged periods of disease inactivity without retreatment in part through the immunological results of their pulsatile lymphocyte depletion. It is vital to increase our understanding of how IRTs alter a patient's immune response to the antigenic target of the disease so that we can devise newer, more durable and safer forms of such agents. What common features do extant IRTs (i.e., stem cell transplant, alemtuzumab and oral cladribine) have to produce the durable therapeutic response without long term treatment in neuroimmunological diseases such as MS (multiple sclerosis) and NMOSD (neuromyelitis optica spectrum disorders)? Can we learn from these critical features to predict what other maneuvers or agents might effect similar clinical results with equal or greater efficacy and safety?

Peripheral blood and bronchoalveolar leukocyte profile in lung transplant recipients and their changes according to immunosuppressive regimen: A single-center experience

BACKGROUND

After lung transplantation (LuTX), lower respiratory tract infections (LRTI) and acute cellular rejection (ACR) are associated with changes in peripheral blood and bronchoalveolar lavage fluid mononuclear cell profile (PBMC and BALIC). PBMC is also influenced by immunosuppressive regimen and its changes with postoperative time. First-year PBMC and BALIC changes were evaluated in this study with rabbit anti-thymocyte globulin (ATG) and alemtuzumab (AL) induction therapy.

METHODS

In total, 64 LuTX recipients were included, 53 of them received AL and 11 ATG as induction therapy. PBMC and BALIC were examined routinely and in cases suspicious of infection and/or rejection. A PBMC- and BALIC-based algorithm for infection and rejection prediction was also tested.

RESULTS

In the AL group, peripheral blood lymphocyte and basophil cell numbers were significantly reduced, while the neutrophil cell number elevation during LRTI was significantly higher compared to the control. Early postoperative measurements showed a lower BALIC lymphocyte count. The algorithm had 17% sensitivity and 94% specificity for ACR in all patients and 33% sensitivity and 95% specificity for ACR with coexisting LRTI.

CONCLUSION

BALIC is not significantly influenced by the immunosuppressive regimen. PBMC- and BALIC-based algorithm may improve the differential diagnosis of ACR.

HDAC Inhibition as Potential Therapeutic Strategy to Restore the Deregulated Immune Response in Severe COVID-19

The COVID-19 pandemic has had a devastating impact worldwide and has been a great challenge for the scientific community. Vaccines against SARS-CoV-2 are now efficiently lessening COVID-19 mortality, although finding a cure for this infection is still a priority. An unbalanced immune response and the uncontrolled release of proinflammatory cytokines are features of COVID-19 pathophysiology and contribute to disease progression and worsening. Histone deacetylases (HDACs) have gained interest in immunology, as they regulate the innate and adaptative immune response at different levels. Inhibitors of these enzymes have already proven therapeutic potential in cancer and are currently being investigated for the treatment of autoimmune diseases. We thus tested the effects of different HDAC inhibitors, with a focus on a selective HDAC6 inhibitor, on immune and epithelial cells in in vitro models that mimic cells activation after viral infection. Our data indicate that HDAC inhibitors reduce cytokines release by airway epithelial cells, monocytes and macrophages. This anti-inflammatory effect occurs together with the reduction of monocytes activation and T cell exhaustion and with an increase of T cell differentiation towards a T central memory phenotype. Moreover, HDAC inhibitors hinder IFN-I expression and downstream effects in both airway epithelial cells and immune cells, thus potentially counteracting the negative effects promoted in critical COVID-19 patients by the late or persistent IFN-I pathway activation. All these data suggest that an epigenetic therapeutic approach based on HDAC inhibitors represents a promising pharmacological treatment for severe COVID-19 patients.

Clinical and Molecular Profiling to Develop a Potential Prediction Model for the Response to Alemtuzumab Therapy for Acute Kidney Transplant Rejection

Alemtuzumab, a monoclonal antibody that depletes CD52‐bearing immune cells, is an effective drug for the treatment of severe or glucocorticoid‐resistant acute kidney transplant rejection (AR). Patient‐specific predictions on treatment response are, however, urgently needed, given the severe side effects of alemtuzumab. This study developed a multidimensional prediction model with the aim of generating clinically useful prognostic scores for the response to alemtuzumab. Clinical and histological characteristics were collected retrospectively from patients who were treated with alemtuzumab for AR. In addition, targeted gene expression profiling of AR biopsy tissues was performed. Least absolute shrinkage and selection operator (LASSO) logistic regression modeling was used to construct the ALEMtuzumab for Acute Rejection (ALEMAR) prognostic score. Response to alemtuzumab was defined as patient and allograft survival and at least once an estimated glomerular filtration rate (eGFR) > 30 mL/min/1.73 m² during the first 6 months after treatment. One hundred fifteen patients were included, of which 84 (73%) had a response to alemtuzumab. The ALEMAR‐score accurately predicted the chance of response. Gene expression analysis identified 13 differentially expressed genes between responders and nonresponders. The combination of the ALEMAR‐score and selected genes resulted in improved predictions of treatment response. The present preliminary prediction model is potentially helpful for the development of stratified alemtuzumab treatment for acute kidney transplant rejection but requires validation.

Disproportional increase in psoriasis reports in association with B cell depleting therapies in patients with multiple sclerosis

BACKGROUND

Some pathways involved in the pathogenesis of psoriasis share similarities with processes involved in multiple sclerosis (MS) pathogenesis. However, the association between MS and psoriasis is poorly understood. Since disease-modifying therapies for MS have various targets, it may be possible that the occurrence of psoriasis varies by drug.

OBJECTIVE

To analyze the frequency of psoriasis reports in patients treated with various disease-modifying therapies for MS.

METHODS

Data was collected using the FDA Adverse Event Reporting System (FAERS) and OpenFDA database between January 2009 and June 2020. The study analyzed total reports of psoriasis out of total reports in the "Skin and Subcutaneous Tissue Disorders" category for each drug and explored age, sex distribution, and report source. OpenFDA data was used to perform statistical analyses including reporting odds ratios (ROR) and information components.

RESULTS

The study identified 517 psoriasis reports of 45,547 total skin and subcutaneous tissue disorders (1.13%) in FAERS. The highest proportions of reports in this study were associated with rituximab, ocrelizumab, and interferon beta 1a. The lowest proportion of reports were associated with glatiramer acetate, alemtuzumab, dimethyl fumarate and teriflunomide. Reports of other autoimmune skin disorders were minimal (29 vitiligo, 33 pemphigoid, and 7 pemphigus). Patients primarily drove reports for most DMTs versus healthcare providers. The proportion of reports from female patients were the highest for each DMT except alemtuzumab. OpenFDA query retrieved 302 total reports of psoriasis. Significantly increased reporting odds ratios (RORs, 95% confidence interval) of psoriasis were noted for rituximab (7.14, 3.92-13.00), ocrelizumab (3.79, 2.74-5.23), and fingolimod (1.33, 1.01-1.76). Significantly decreased RORs were noted for natalizumab (0.53, 0.36-0.80), glatiramer acetate (0.58, 0.35-0.96), and dimethyl fumarate (0.71, 0.53-0.94).

CONCLUSION

There are frequent reports of psoriasis in MS patients treated with various DMTs. However, reports and RORs were disproportionally high in association with B cell depleting therapies. Further research is required to determine if certain DMTs may serve as better options for individuals affected by, or at high-risk for developing psoriasis.

Rate of recipient-derived alveolar macrophage development and major histocompatibility complex cross-decoration after lung transplantation in humans

Alveolar macrophages (AM) play critical roles in lung tissue homeostasis, host defense, and modulating lung injury. The rate of AM turnover (donor AM replacement by circulating monocytes) after transplantation has been incompletely characterized. Furthermore, the anatomic pattern of recipient-derived lung macrophages repopulation has not been reported, nor has their ability to accumulate and present donor major histocompatibility complex (a process we refer to as MHC cross-decoration). We longitudinally characterized the myeloid content of bronchoalveolar lavage (BAL) and biopsy specimens of lung transplant recipients and found a biphasic rate in AM turnover in the allograft, with a rapid turnover perioperatively, accelerated by both the type of induction immunosuppression and the presence of primary graft dysfunction. We found that recipient myeloid cells with cell surface AM phenotype repopulated the lung in a disorganized pattern, comprised mainly of large clusters of cells. Finally, we show that recipient AM take up and present donor peptide-MHC complexes yet are not able to independently induce an in vitro alloreactive response by circulating recipient T cells.

Loss of thymic function promotes EAE relapse in anti-CD52-treated mice

Anti-CD52 treatment creates a long-lasting CD4 T cell lymphopenia and reduces multiple sclerosis (MS) relapses in humans. In contrast, anti-CD52 therapy at disease onset more fully suppresses experimental autoimmune encephalomyelitis (EAE) in mice, and T cell repopulation is rapid. To test whether prolonged T cell lymphopenia promotes relapses, we thymectomized mice prior to EAE induction and anti-CD52 treatment. Thymectomy greatly reduced the number of recent thymic emigrant T cells and was associated with a prolonged reduction in CD4 T cells in peripheral blood. Two-thirds of thymectomized C57BL/6 mice had an EAE relapse post anti-CD52 treatment, while no surgery and sham surgery euthymic controls remained relapse-free. These data demonstrate that thymus function can alter the effectiveness of anti-CD52 treatment.

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Thymectomy significantly reduces the proportion of newly generated T cells.

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Thymectomy predisposes anti-CD52-treated mice to EAE relapse.

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Thymectomy-promoted EAE relapse in anti-CD52 treated mice is associated with weight decline and prolonged T cell lymphopenia.

Anti-CD52 antibody treatment in murine experimental autoimmune encephalomyelitis induces dynamic and differential modulation of innate immune cells in peripheral immune and central nervous systems

Anti‐CD52 antibody (anti‐CD52‐Ab) leads to a rapid depletion of T and B cells, followed by reconstitution of immune cells with tolerogenic characteristics. However, very little is known about its effect on innate immune cells. In this study, experimental autoimmune encephalomyelitis mice were administered murine anti‐CD52‐Ab to investigate its effect on dendritic cells and monocytes/macrophages in the periphery lymphoid organs and the central nervous system (CNS). Our data show that blood and splenic innate immune cells exhibited significantly increased expression of MHC‐II and costimulatory molecules, which was associated with increased capacity of activating antigen‐specific T cells, at first day but not three weeks after five daily treatment with anti‐CD52‐Ab in comparison with controls. In contrast to the periphery, microglia and infiltrating macrophages in the CNS exhibited reduced expression levels of MHC‐II and costimulatory molecules after antibody treatment at both time‐points investigated when compared to controls. Furthermore, the transit response of peripheral innate immune cells to anti‐CD52‐Ab treatment was also observed in the lymphocyte‐deficient SCID mice, suggesting the changes are not a direct consequence of the mass depletion of lymphocytes in the periphery. Our study demonstrates a dynamic and tissue‐specific modulation of the innate immune cells in their phenotype and function following the antibody treatment. The findings of differential modulation of the microglia and infiltrating macrophages in the CNS in comparison with the innate immune cells in the peripheral organs support the CNS‐specific beneficial effect of alemtuzumab treatment on inhibiting neuroinflammation in multiple sclerosis patients.

Telmisartan restricts Chikungunya virus infection in vitro and in vivo through the AT1/PPAR-γ/MAPKs pathways

Chikungunya virus (CHIKV) has re-emerged as a global public health threat. The inflammatory pathways of RAS and PPAR-γ are usually involved in viral infections. Thus, Telmisartan (TM) with known capacity to block AT1 receptor and activate PPAR-γ, was investigated against CHIKV. The anti-CHIKV effect of TM was investigated in vitro (Vero, RAW 264.7 cells and hPBMCs) and in vivo (C57BL/6 mice). TM was found to abrogate CHIKV infection efficiently (IC50 of 15.34-20.89μM in the Vero and RAW 264.7 cells respectively). Viral RNA and proteins were reduced remarkably. Additionally, TM interfered in the early and late stages of CHIKV life cycle with efficacy in both pre and post-treatment assay. Moreover, the agonist of AT1 receptor and antagonist of PPAR-γ increased CHIKV infection suggesting TM's anti-viral potential by modulating host factors. Besides, reduced activation of all major MAPKs, NF-κB (p65) and cytokines by TM through the inflammatory axis supported the fact that the anti-CHIKV efficacy of TM is partly mediated through the AT1/PPAR-γ/MAPKs pathways. Interestingly, at the human equivalent dose, TM abrogated CHIKV infection and inflammation significantly leading to reduced clinical score and complete survival of C57BL/6 mice. Additionally, TM reduced infection in hPBMC derived monocyte-macrophage populations in vitro. Hence, TM was found to reduce CHIKV infection by targeting both viral and host factors. Considering its safety and in vivo efficacy, it can be a suitable candidate in future for repurposing against CHIKV.

Anti-CD52 Therapy for Multiple Sclerosis: An Update in the COVID Era

CD52 is a small surface glycoprotein composed of 12 amino acids. CD52 is found mostly on the surface of mature immune cells, such as lymphocytes, monocytes, eosinophils, and dendritic cells, as well as the male genital tract: within the epididymis and on the surface of mature sperm. Low CD52 expression is also found in neutrophils. CD52 function is not fully understood, although experiments with anti-CD52 antibodies have shown that CD52 is essential for lymphocyte transendothelial migration and may contribute to costimulation of CD4+ T cells and T-cell activation and proliferation. Although knowledge about exact CD52 function is still poor, CD52 presence on the surface of a broad spectrum of immune cells makes it a therapeutic target, especially in immunomediated diseases, such as multiple sclerosis. In multiple sclerosis, alemtuzumab is registered for adult patients with the relapsing-remitting form of the disease defined by clinical and imaging features. Despite the high efficacy of the drug, the main issue is its safety. The main adverse effects of alemtuzumab are associated with drug infusion due to cytokine release and cytotoxic effects of antibodies associated with lymphocyte depletion, which leads to immunosuppression, and secondary autoimmunity that may be the effect of excessive B-cell repopulation and cancer. This review presents current knowledge on the drug's mechanism of action, efficacy and safety data from clinical trials, and real-world observations, including available though scarce data on using alemtuzumab in the COVID era.

Current and Future Immunotherapies for Multiple Sclerosis

Despite substantial progress in developing new immunotherapies against multiple sclerosis (MS), currently available immunotherapies are only partially effective for this debilitating neurological disease, thus necessitating new therapeutic approaches. Here, we review the immunotherapies already approved for MS as well as relevant clinical trials. Further, we present some experimental approaches that are currently being developed and are focused on modulating the functions of dendritic cells and regulatory T cells.

Influence of Pregnancy in Multiple Sclerosis and Impact of Disease-Modifying Therapies

Purpose of this Review: This article is a systematic review on the influence pregnancy has on multiple sclerosis and the resulting impact of disease-modifying therapies.

Findings: Multiple sclerosis predominantly affects young women with a clinical onset most often during the child-bearing age. The impact of multiple sclerosis and disease-modifying therapies on fertility, pregnancy, fetal outcome, and breastfeeding is a pivotal topic when it comes to clinical practice. The introduction of disease-modifying therapies has changed not only the natural history of the disease but also the perspective of pregnancy in women with multiple sclerosis. Family planning requires careful consideration, especially because many disease-modifying drugs are contraindicated during pregnancy. In this article, we review current evidence collected from published literature and drug-specific pregnancy registers on the use of disease-modifying therapies. Additionally, we discuss safety profiles for each drug and correlate them to both risk for the exposed fetus and risk for the mothers interrupting treatments when seeking pregnancy.

Therapeutic Value of Single Nucleotide Polymorphisms on the Efficacy of New Therapies in Patients with Multiple Sclerosis

The introduction of new therapies for the treatment of multiple sclerosis (MS) is a very recent phenomenon and little is known of their mechanism of action. Moreover, the response is subject to interindividual variability and may be affected by genetic factors, such as polymorphisms in the genes implicated in the pathologic environment, pharmacodynamics, and metabolism of the disease or in the mechanism of action of the medications, influencing the effectiveness of these therapies. This review evaluates the impact of pharmacogenetics on the response to treatment with new therapies in patients diagnosed with MS. The results suggest that polymorphisms detected in the GSTP1, ITGA4, NQO1, AKT1, and GP6 genes, for treatment with natalizumab, ZMIZ1, for fingolimod and dimethyl fumarate, ADA, for cladribine, and NOX3, for dimethyl fumarate, may be used in the future as predictive markers of treatment response to new therapies in MS patients. However, there are few existing studies and their samples are small, making it difficult to generalize the role of these genes in treatment with new therapies. Studies with larger sample sizes and longer follow-up are therefore needed to confirm the results of these studies.

Flow cytometric evaluation of CD38 expression levels in the newly diagnosed T-cell acute lymphoblastic leukemia and the effect of chemotherapy on its expression in measurable residual disease, refractory disease and relapsed disease: an implication for anti-CD38 immunotherapy

Background

Recently, anti-CD38 monoclonal antibody (Mab) therapy has become a focus of attention as an additional/alternative option for many hematological neoplasms including T-cell acute lymphoblastic leukemia (T-ALL). It has been shown that antitumor efficacy of anti-CD38-Mab depends on the level of CD38 expression on tumor cells. Reports on CD38 expression in T-ALL are scarce, and data on the effect of cytotoxic chemotherapy on CD38 expression are limited to very few samples. Moreover, it lacks entirely in refractory disease and in adult T-ALL. We report the flow cytometric evaluation of CD38 expression in T-ALL blasts at diagnosis and the effect of cytotoxic chemotherapy on its expression in measurable residual disease (MRD), refractory disease (MRD≥5%), and relapsed disease in a large cohort of T-ALL.

Methods

The study included 347 samples (188 diagnostic, 100 MRD, 24 refractory and 35 relapse samples) from 196 (children: 85; adolescents/adults: 111) patients with T-ALL. CD38-positive blasts percentages (CD38-PBPs) and expression-intensity (mean fluorescent intensity, CD38-MFI) were studied using multicolor flow cytometry (MFC). MFC-based MRD was performed at the end-of-induction (EOI-MRD, day 30–35) and end-of-consolidation (EOC-MRD, day 78–85) subsequent follow-up (SFU-MRD) points.

Results

Patients were classified into early thymic precursor subtype of T-ALL (ETPALL, 54/188, 28.7%), and non-ETPALL (134/188, 71.3%). Of 188, EOI-MRD assessment was available in 152, EOC-MRD was available in 96 and SFU-MRD was available in 14 patients. CD38 was found positive in 97.9% (184/188) of diagnostic, 88.7% (110/124) MRD (including 24-refractory) and 82.9% (29/35) relapsed samples. Median (95% CI) of CD38-PBPs/MFI in diagnostic, MRD, refractory, and relapsed T-ALL samples were, respectively, 85.9% (82.10%–89.91%)/4.2 (3.88–4.47), 74.0% (58.87%–83.88%)/4.6 (3.67–6.81), 79.6% (65.25%–96.11%)/4.6 (3.33–8.47) and 85.2% (74.48%–93.01%)/5.6 (4.14–8.99). No significant difference was noted in CD38 expression between pediatric versus adult and patients with ETPALL versus non-ETPALL. No change was observed in CD38-MFI between diagnostic versus MRD and diagnostic versus relapsed paired samples. However, we noticed a mild drop in the CD38-PBPs in MRD samples compared with the diagnostic samples (p=0.016).

Conclusion

We report an in-depth analysis of CD38 expression in a large cohort of T-ALL at diagnosis, during chemotherapy, and at relapse. Our data demonstrated that CD38 is robustly expressed in T-ALL blasts with a little effect of cytotoxic chemotherapy making it a potentially effective target for antiCD38-Mab therapy.

Effectiveness and safety of alemtuzumab in the treatment of active relapsing-remitting multiple sclerosis: a multicenter, observational study

OBJECTIVE

So far, a limited number of real-world evidence studies about the effectiveness and safety of alemtuzumab (ALM) have been published, some of them with a relatively small number of included patients. We aimed to study the efficacy and safety of ALM in real-world clinical practice in two MS centers in Slovenia and Croatia.

METHODS

This was a retrospective chart review of 71 consecutive patients with relapsing-remitting MS who were treated with ALM from 2015 till 2018. The following data were collected: gender, age at disease onset, disease duration at ALM initiation, previous disease modifying therapy, number of relapses, active MRI lesions, and EDSS in the year prior to ALM initiation and every year of follow-up.

RESULTS

All patients completed the standard dosing schedule and were followed for a mean time of 3.2±1.1 years after the initiation of treatment. Complete data for the 2 years after treatment (relapses, EDSS, and MRI) were available for 48 patients, of which 14 (29.2%) achieved NEDA. Clinical NEDA was achieved in 38 out of 63 participants (60.3%). In year 1, 24 out of 57 (42.1%) patients achieved NEDA. In year 2, 26 out of 41 (63.4%) patients achieved NEDA. Lower EDSS prior to starting ALM was the only independent predictor of NEDA in a multivariable model. Adverse events occurred in 58 participants (84.1%), with no new safety signals identified.

CONCLUSION

According to the data from our cohort of early active RRMS patients we conclude ALM efficacy remains high in the real-world clinical practice.

Alemtuzumab mediates the CD39+ T-regulatory cell response via CD23+ macrophages

Alemtuzumab (ALM) effectively prevents relapses of multiple sclerosis (MS). It causes lymphocyte depletion with subsequent enhancement of the T-regulatory cell population. Direct administration of ALM to T cells causes cytolysis. However, the T cells may be indirectly affected by monocyte-derived cells, which are resistant to ALM cytotoxicity. We aimed to examine whether ALM modulates monocytes and whether the crosstalk between monocytes and lymphocytes previously exposed to ALM would result in anti-inflammatory effects. The CD14⁺ monocytes of 10 healthy controls and 10 MS (treatment naive) patients were isolated from peripheral blood mononuclear cells (PBMCs), exposed to ALM and reintroduced to PBMCs depleted of CD14⁺ cells. The macrophage profile was assessed and T-cell markers were measured. ALM promoted M2 anti-inflammatory phenotype as noted by an increased percentage in the populations of CD23⁺ , CD83⁺ and CD163⁺ cells. The CD23⁺ cells were the most upregulated (7-fold, P = 0.0002), and the observed effect was higher in patients with MS than in healthy subjects. ALM-exposed macrophages increased the proportion of T-regulatory cells, without affecting the proportion of T-effector cells. Neutralizing the CD23⁺ monocytes with antibodies reversed the effect specifically on the CD4⁺ CD39⁺ T-regulatory cell subpopulation but not on the CD4⁺ CD25^hi CD127^lo FOXP3⁺ subpopulation. ALM induces the conversion of monocytes into anti-inflammatory macrophages, which in turn promotes T-regulatory cell enhancement, in a CD23-dependent manner. These findings suggest that the mechanism of action of ALM is relevant to aspects of MS pathogenesis.

CD52 Is Elevated on B cells of SLE Patients and Regulates B Cell Function

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by B cell dysregulation and breaks in tolerance that lead to the production of pathogenic autoantibodies. We performed single-cell RNA sequencing of B cells from healthy donors and individuals with SLE which revealed upregulated CD52 expression in SLE patients. We further demonstrate that SLE patients exhibit significantly increased levels of B cell surface CD52 expression and plasma soluble CD52, and levels of soluble CD52 positively correlate with measures of lupus disease activity. Using CD52-deficient JeKo-1 cells, we show that cells lacking surface CD52 expression are hyperresponsive to B cell receptor (BCR) signaling, suggesting an inhibitory role for the surface-bound protein. In healthy donor B cells, antigen-specific BCR-activation initiated CD52 cleavage in a phospholipase C dependent manner, significantly reducing cell surface levels. Experiments with recombinant CD52-Fc showed that soluble CD52 inhibits BCR signaling in a manner partially-dependent on Siglec-10. Moreover, incubation of unstimulated B cells with CD52-Fc resulted in the reduction of surface immunoglobulin and CXCR5. Prolonged incubation of B cells with CD52 resulted in the expansion of IgD+IgMlo anergic B cells. In summary, our findings suggest that CD52 functions as a homeostatic protein on B cells, by inhibiting responses to BCR signaling. Further, our data demonstrate that CD52 is cleaved from the B cell surface upon antigen engagement, and can suppress B cell function in an autocrine and paracrine manner. We propose that increased expression of CD52 by B cells in SLE represents a homeostatic mechanism to suppress B cell hyperactivity.

Multiple Sclerosis and SARS-CoV-2 Vaccination: Considerations for Immune-Depleting Therapies

Several concerns have been raised about the use of immunodepleting agents including alemtuzumab, cladribine and CD20-depleting antibodies in people with multiple sclerosis (pwMS) during the coronavirus disease (COVID) 2019 pandemic. As the end of the pandemic is not yet in sight, vaccination against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) may be an elegant strategy to overcome the potential hazards associated with initiating and continuing treatment with immune-depleting agents. In this review, we summarize the immunological effects of immune-depleting therapy and underlying considerations for the hitherto existing recommendations that suggest a restricted use of immune-deleting therapies during the pandemic. Moreover, we critically discuss open questions regarding vaccination in general and against SARS-CoV-2 in pwMS.

Alemtuzumab outcomes by age: Post hoc analysis from the randomized CARE-MS studies over 8 years

BACKGROUND

Alemtuzumab significantly improved clinical and MRI outcomes vs. subcutaneous interferon beta-1a (SC IFNB-1a) in the CARE-MS trials (NCT00530348, NCT00548405), with sustained efficacy in 2 consecutive extensions (NCT00930553, NCT02255656 [TOPAZ]).

METHODS

Post hoc analysis of 8-year alemtuzumab efficacy and safety in pooled CARE-MS patients (N=811) stratified by baseline age (≥18 to ≤25, >25 to ≤35, >35 to ≤45, >45 to ≤55 years).

RESULTS

Compared with SC IFNB-1a over 2 years across age cohorts, alemtuzumab lowered annualized relapse rates (ARR; 0.22-0.24 vs. 0.38-0.51), improved or stabilized disability (freedom from 6-month confirmed disability worsening [CDW]: 85%-92% vs. 62%-88%; achievement of 6-month confirmed disability improvement [CDI]: 20%-31% vs. 13%-25%), increased proportions free of MRI disease activity (70%-86% vs. 42%-63% per year), and slowed brain volume loss (BVL; -0.45% to -0.87% vs. -0.50% to -1.39%). Through Year 2, the treatment effect with alemtuzumab did not significantly differ among age groups for ARR (p-interaction=0.6325), 6-month CDW-free (p-interaction=0.4959), 6-month CDI (p-interaction=0.9268), MRI disease activity-free (p-interaction=0.6512), and BVL (p-interaction=0.4970). Alemtuzumab remained effective on outcomes through Year 8 across age groups. Age-related increases in malignancies (≤45 years: 0.9%-2.2% vs. >45 years: 8.1%) and deaths (0%-1.7% vs. 7.0%) were observed. Serious infections also increased from the youngest (5.1%) to oldest (12.8%) age cohorts.

CONCLUSIONS

Alemtuzumab had greater efficacy than SC IFNB-1a over 2 years across comparable age groups, with no significant differences between alemtuzumab-treated age groups. Efficacy on relapse, disability, and MRI outcomes continued through Year 8 across age groups. Age-related increases in serious infections, malignancies, and deaths were observed.

The blood endothelial cell chamber - An innovative system to study immune responses in drug development

The risk for adverse immune-mediated reactions, associated with the administration of certain immunotherapeutic agents, should be mitigated early. Infusion reactions to monoclonal antibodies and other biopharmaceuticals, known as cytokine release syndrome, can arise from the release of cytokines via the drug target cell, as well as the recruitment of immune effector cells. While several in vitro cytokine release assays have been proposed up to date, many of them lack important blood components, required for this response to occur. The blood endothelial cell chamber model is an in vitro assay, composed of freshly drawn human whole blood and cultured human primary endothelial cells. Herein, its potential to study the compatibility of immunotherapeutics with the human immune system was studied by evaluating three commercially available monoclonal antibodies and bacterial endotoxin lipopolysaccharide. We demonstrate that the anti-CD28 antibody TGN1412 displayed an adaptive cytokine release profile and a distinct IL-2 response, accompanied with increased CD3⁺ cell recruitment. Alemtuzumab exhibited a clear cytokine response with a mixed adaptive/innate source (IFNγ, TNFα and IL-6). Its immunosuppressive nature is observed in depleted CD3⁺ cells. Cetuximab, associated with low infusion reactions, showed a very low or absent stimulatory effect on proinflammatory cytokines. In contrast, bacterial endotoxin demonstrated a clear innate cytokine response, defined by TNFα, IL-6 and IL-1β release, accompanied with a strong recruitment of CD14⁺CD16⁺ cells. Therefore, the blood endothelial cell chamber model is presented as a valuable in vitro tool to investigate therapeutic monoclonal antibodies with respect to cytokine release and vascular immune cell recruitment.

Second-generation immunotherapeutics in multiple sclerosis: can we discard their precursors?

Options for disease-modifying therapies in multiple sclerosis have increased over the past two decades. Among these innovations are interferon-β, glatiramer acetate, fumaric acid and dihydroorotate dehydrogenase inhibitors, an antibody targeting the migration of immune cells, a compound that traps immune cells in lymphoid organs by sphingosine 1-phosphate receptor (S1PR) modulation and immune-reconstitution therapies. Second-generation drugs such as pegylated interferon-β, advanced CD20 depleting antibodies, more-specific S1PR modulators and new formulations have been developed to achieve higher efficacy while exhibiting fewer side effects. In this review, we address the shortcomings of the parent drugs, present the pros and cons of the second-generation therapies and summarize upcoming developments in the field of immunotherapy for multiple sclerosis.

Human innate lymphoid cell precursors express CD48 that modulates ILC differentiation through 2B4 signaling

Innate lymphoid cells (ILCs) develop from common lymphoid progenitors (CLPs), which further differentiate into the common ILC progenitor (CILP) that can give rise to both ILCs and natural killer (NK) cells. Murine ILC intermediates have recently been characterized, but the human counterparts and their developmental trajectories have not yet been identified, largely due to the lack of homologous surface receptors in both organisms. Here, we show that human CILPs (CD34+CD117+α4β7+Lin-) acquire CD48 and CD52, which define NK progenitors (NKPs) and ILC precursors (ILCPs). Two distinct NK cell subsets were generated in vitro from CD34+CD117+α4β7+Lin-CD48-CD52+ and CD34+CD117+α4β7+Lin-CD48+CD52+ NKPs, respectively. Independent of NKPs, ILCPs exist in the CD34+CD117+α4β7+Lin-CD48+CD52+ subset and give rise to ILC1s, ILC2s, and NCR+ ILC3s, whereas CD34+CD117+α4β7+Lin-CD48+CD52- ILCPs give rise to a distinct subset of ILC3s that have lymphoid tissue inducer (LTi)-like properties. In addition, CD48-expressing CD34+CD117+α4β7+Lin- precursors give rise to tissue-associated ILCs in vivo. We also observed that the interaction of 2B4 with CD48 induced differentiation of ILC2s, and together, these findings show that expression of CD48 by human ILCPs modulates ILC differentiation.

Effects of Alemtuzumab on (Auto)antigen-Specific Immune Responses

Alemtuzumab (anti-CD52 mAb) leads to a long-lasting disease activity suppression in patients with relapsing forms of multiple sclerosis (MS). In this study, we examined the change of the immune cell repertoire and the cellular reactivity after treatment with alemtuzumab. We analyzed the number of IFN-γ–secreting cells in presence of several peptides which had been eluted from the central nervous system (CNS) of MS patients and are possible targets of autoreactive T cells in MS. The patients showed a stabilized disease activity measured in clinical parameters and lesion formation after the treatment. We detected a reduction of the number of IFN-γ–secreting cells in the presence of every tested self-antigen. The number of IFN-γ–secreting cells was also reduced in the presence of non-self-antigens. We also found a clear change in the immune cell repertoire. After an almost complete depletion of all lymphocytes, the cell specificities showed different reconstitution patterns, resulting in different cell fractions. The percentage of CD4+ T cells was clearly reduced after therapy, whereas the fractions of B and NK cells were elevated. When we evaluated the number of IFN-γ–secreting cells in relation to the number of present CD4+ T cells, we still found a significant reduction. We conclude that the reduction of IFN-γ–secreting cells by alemtuzumab is not only due to a reduction of the CD4+ T cell fraction within the peripheral blood mononuclear cell (PBMC) compartment but might also be caused by functional changes or a shift in the distribution of different subtypes in the CD4+ T cell pool.

Mutations in PIGA cause a CD52-/GPI-anchor-deficient phenotype complicating alemtuzumab treatment in T-cell prolymphocytic leukemia

OBJECTIVE

Infusional alemtuzumab followed by consolidating allogeneic hematopoietic stem cell transplantation in eligible patients is considered a standard of care in T-cell prolymphocytic leukemia (T-PLL). Antibody selection against CD52 has been associated with the development of CD52-negative leukemic T cells at time of relapse. Clinical implications and molecular mechanisms underlying this phenotypic switch are unknown.

METHODS

We performed flow cytometry and real-time-PCR for CD52-expression and next generation sequencing for PIGA mutational analyses.

RESULTS

We identified loss of CD52 expression after alemtuzumab treatment in two of 21 T-PLL patients resulting from loss of GPI-anchor expression caused by inactivating mutations of the PIGA gene. One patient with relapsed T-PLL exhibited a single PIGA mutation, causing a CD52-negative escape variant of the initial leukemic cell clone, preventing alemtuzumab-retreatment. The second patient with continued complete remission after alemtuzumab treatment harbored three different PIGA mutations that affected either the non-neoplastic T cell or the mononuclear cell compartment and resulted in symptomatic paroxysmal nocturnal hemoglobinuria. Next generation sequencing of T-PLL cells collected before the initiation of treatment revealed PIGA wild-type sequence reads in all 16 patients with samples available for testing.

CONCLUSION

These data indicate that PIGA mutations were acquired during or after completion of alemtuzumab treatment.

Consequences of treatment for hemophagocytic lymphohistiocytosis in a patient with undiagnosed Gaucher disease Type 1

Gaucher disease, a lysosomal storage disorder and hemophagocytic lymphohistiocytosis (HLH), a disorder of the immune system, have several overlapping clinical features including cytopenias, elevated serum ferritin, and splenomegaly. Prior reports of acute infantile neuronopathic, Type 2 Gaucher disease manifesting with signs of HLH have been published. Here we describe an adult patient who was initially suspected of having HLH, and was treated with a 10-day course of etoposide and a 5-day course alemtuzumab for presumptive HLH, only to later to have his presentation be determined to be due to Type 1 Gaucher disease. HLH chemotherapy treatment appeared to trigger a severe Gaucher acute pain crisis and extensive bony disease including avascular necrosis. Prolonged immunosuppression, and recurrent infections further complicated a lengthy hospitalization. We discuss the clinical overlap between Gaucher and HLH and the iatrogenic consequences of HLH-directed therapy on underlying Type 1 Gaucher disease.

Effect of alemtuzumab-based T-cell depletion on graft compositional change in vitro and immune reconstitution early after allogeneic stem cell transplantation

BACKGROUND AIMS

To reduce the risk of graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (alloSCT), T-cell depletion (TCD) of grafts can be performed by the addition of alemtuzumab (ALT) "to the bag" (in vitro) before transplantation. In this prospective study, the authors analyzed the effect of in vitro incubation with 20 mg ALT on the composition of grafts prior to graft infusion. Furthermore, the authors assessed whether graft composition at the moment of infusion was predictive for T-cell reconstitution and development of GVHD early after TCD alloSCT.

METHODS

Sixty granulocyte colony-stimulating factor-mobilized stem cell grafts were obtained from ≥9/10 HLA-matched related and unrelated donors. The composition of the grafts was analyzed by flow cytometry before and after in vitro incubation with ALT. T-cell reconstitution and incidence of severe GVHD were monitored until 12 weeks after transplantation.

RESULTS

In vitro incubation of grafts with 20 mg ALT resulted in an initial median depletion efficiency of T-cell receptor (TCR) α/β T cells of 96.7% (range, 63.5-99.8%), followed by subsequent depletion in vivo. Graft volumes and absolute leukocyte counts of grafts before the addition of ALT were not predictive for the efficiency of TCR α/β T-cell depletion. CD4^pos T cells were depleted more efficiently than CD8^pos T cells, and naive and regulatory T cells were depleted more efficiently than memory and effector T cells. This differential depletion of T-cell subsets was in line with their reported differential CD52 expression. In vitro depletion efficiencies and absolute numbers of (naive) TCR α/β T cells in the grafts after ALT incubation were not predictive for T-cell reconstitution or development of GVHD post- alloSCT.

CONCLUSIONS

The addition of ALT to the bag is an easy, fast and generally applicable strategy to prevent GVHD in patients receiving alloSCT after myeloablative or non-myeloablative conditioning because of the efficient differential depletion of donor-derived lymphocytes and T cells.

Intensive immunosuppression followed by autologous hematopoietic stem cell transplantation for the treatment of multiple sclerosis

Autologous hematopoietic stem cell transplantation (AHSCT) to treat multiple sclerosis (MS) has mostly been used in devastating cases as the last option to stop further neurological deterioration. However, evidence from several retrospective clinical trials indicates that young, less disabled patients with highly inflammatory active MS are the most likely to benefit from AHSCT, and after moving from high-intensity to nonmyeloablative procedures the tolerability of AHSCT has increased and its associated risk and mortality have declined considerably. Recent meta-analyses and randomized clinical trials show that AHSCT is more effective than currently approved disease-modifying therapies (DMTs), with suppression of disease activity in 70-90% of patients and long-term cessation of disease activity in two-thirds of treated patients. The rationale for AHSCT is to eliminate autoimmunity and achieve immune resetting by intense immunosuppression followed by infusion of autologous hematopoietic stem cells. Similar effects on the immune system have been suggested for cladribine and alemtuzumab treatment and, together with AHSCT, they constitute the induction or immune-reconstitution therapies for MS. Although, further randomized controlled trials of AHSCT for MS are needed, it has become clear that improved patient selection and lower intensity conditioning regimens have reduced AHSCT associated risks and mortality and strengthened the position of AHSCT among other DMTs. Do we have enough experience and scientific support for AHSCT in MS to move from an exclusive treatment for aggressive, treatment-resistant MS and acquire broader indications, similar to other effective DMTs?

Molecular Effects of FDA-Approved Multiple Sclerosis Drugs on Glial Cells and Neurons of the Central Nervous System

Multiple sclerosis (MS) is characterized by peripheral and central inflammatory features, as well as demyelination and neurodegeneration. The available Food and Drug Administration (FDA)-approved drugs for MS have been designed to suppress the peripheral immune system. In addition, however, the effects of these drugs may be partially attributed to their influence on glial cells and neurons of the central nervous system (CNS). We here describe the molecular effects of the traditional and more recent FDA-approved MS drugs Fingolimod, Dimethyl Fumarate, Glatiramer Acetate, Interferon-β, Teriflunomide, Laquinimod, Natalizumab, Alemtuzumab and Ocrelizumab on microglia, astrocytes, neurons and oligodendrocytes. Furthermore, we point to a possible common molecular effect of these drugs, namely a key role for NFκB signaling, causing a switch from pro-inflammatory microglia and astrocytes to anti-inflammatory phenotypes of these CNS cell types that recently emerged as central players in MS pathogenesis. This notion argues for the need to further explore the molecular mechanisms underlying MS drug action.

Role of Viruses in the Pathogenesis of Multiple Sclerosis

Multiple sclerosis (MS) is an immune inflammatory disease, where the underlying etiological cause remains elusive. Multiple triggering factors have been suggested, including environmental, genetic and gender components. However, underlying infectious triggers to the disease are also suspected. There is an increasing abundance of evidence supporting a viral etiology to MS, including the efficacy of interferon therapy and over-detection of viral antibodies and nucleic acids when compared with healthy patients. Several viruses have been proposed as potential triggering agents, including Epstein-Barr virus, human herpesvirus 6, varicella-zoster virus, cytomegalovirus, John Cunningham virus and human endogenous retroviruses. These viruses are all near ubiquitous and have a high prevalence in adult populations (or in the case of the retroviruses are actually part of the genome). They can establish lifelong infections with periods of reactivation, which may be linked to the relapsing nature of MS. In this review, the evidence for a role for viral infection in MS will be discussed with an emphasis on immune system activation related to MS disease pathogenesis.

The Meaning of Immune Reconstitution after Alemtuzumab Therapy in Multiple Sclerosis

Alemtuzumab is a monoclonal antibody that binds to CD52, a protein present on the surface of mature lymphocytes, but not on the stem cells from which these lymphocytes are derived. It is currently used as an immune reconstitution therapy in patients with relapsing-remitting multiple sclerosis. Alemtuzumab treatment is an intermittent infusion that induces long-term remission of Multiple Sclerosis also in the treatment-free period. After the robust T and B cell depletion induced by alemtuzumab, the immune system undergoes radical changes during its reconstitution. In this review, we will discuss the current knowledge on the reconstitution of the lymphocyte repertoire after alemtuzumab treatment and how it could affect the development of side effects, which led to its temporary suspension by the European Medical Agency.