Clinical profile and challenges faced in the management of optic neuritis: the Indian scenario.

PURPOSE: Optic neuritis (ON) is a relatively common ophthalmic disease that has recently received renewed attention owing to immunological breakthroughs. We studied the profile of patients with ON with special reference to antibody-mediated ON and the challenges faced in its management. METHODS: Case records of patients with ON presenting to a tertiary eye-care center in South India were analyzed. Data on demographics, presenting visual acuity (VA), clinical features, seropositivity for aquaporin-4 immunoglobulin G (AQP4-IgG) and myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG), details of magnetic resonance imaging (MRI) of orbits and brain, and treatment were collected. RESULTS: Among 138 cases with acute ON, male: female ratio was 1:2. Isolated ON was present in 41.3% of cases. Antibody testing of sera was performed in 68 patients only due to financial limitations. Among these, 48.5% were MOG-IgG-seropositive, 11.76% were AQP4-IgG-seropositive, and 30.88% samples were double seronegative. Other causes included multiple sclerosis (n = 4), lactational ON (n = 4), tuberculosis (n = 2), invasive perineuritis (n = 2), COVID-19 vaccination (n = 2), and COVID-19 (n = 1). The mean presenting best corrected visual acuity (BCVA) was 1.31 ± 1.16 logMAR (logarithm of the minimum angle of resolution). The mean BCVA at 3 months was 0.167 ± 0.46 logMAR. Only initial VA ≤ 'Counting fingers' (CF) had a significant association with the visual outcome for final VA worse than CF. The steep cost of investigations and treatment posed challenges for many patients in the management of ON. CONCLUSION: MOG-IgG-associated ON is common in India. Unfortunately, financial constraints delay the diagnosis and timely management of ON, adversely affecting the outcome.

Systemic Connective Tissue Disease and Neuromyelitis Optica Spectrum Disorder Coexistence: A Systematic Review and Meta-Analysis.

BACKGROUND: Several results support the hypothesis that a group of pathologies falling within the Neuromyelitis Optica Spectrum Disorders (NMOSD) diagnostic criteria may coexist with Connective Tissue Diseases (CTD) in patients with a high susceptibility to autoimmune conditions. However, the relationship between NMOSD and rheumatologic diseases deserves further investigations to clarify all clinical aspects of this coexistence. We designed a systematic review and a proportional meta-analysis to estimate the association between CTD and MNOSD, with the aim of helping to plan the best strategy to achieve the most significant public health benefit for these conditions. METHODS: We conducted a systematic review of the literature published until February 2023, searching in four databases: PubMed, Web of Science, EmBase, and OVID. Then, we conducted a random-effects proportional meta-analysis and assessed the risk of bias of the included studies using the Joanna Briggs Institute checklist. RESULTS: The literature search yielded an overall result of 3176 publications (272 from PubMed, 880 from Web of Science, 634 from EmBase and 1390 from OVID). Of these, 29 were included in this systematic review. Analyzing studies that recruited unselected patients with Systemic Lupus Erythematosus (SLE) and Sjogren Syndrome (SjS), the pooled percentages of NMOSD overlapping were 0.6% (95% Confidence Interval [95% CI]: 0.1%-1.4%,) and 6.5% (95% CI: 4.7-8.6), respectively. Studies enrolling rheumatologic patients with nervous system symptoms involvement reported higher percentage of NMOSD (i.e., among SjS patients, a pooled percentage of 26.5%, 95% CI: 5.5-54.6%, was found). Similarly, recruiting patients with NMOSD, we found pooled percentages of SjS or SLE respectively of 7.0% and 3.5%. CONCLUSIONS: Our research found that the coexistence of these two disorders was more frequent in female rheumatologic patients with a SjS diagnosis with neurological manifestations and in neurologic patients for whom a SjS diagnosis was suspected. Similarly, NMOSD are less frequently found in SLE and very rarely incident in Mixed Connective Tissue Disease (MCTD) patients. These considerations should be taken into account in clinical experience of rheumatologists and neurologists, since early diagnosis of both conditions may influence the timing of immunosuppressive therapy and the prevention of systemic disabilities.

Aquaporin 4 Mediates the Effect of Iron Overload on Hydrocephalus After Intraventricular Hemorrhage.

BACKGROUND: Iron overload plays an important role in hydrocephalus development following intraventricular hemorrhage (IVH). Aquaporin 4 (AQP4) participates in the balance of cerebrospinal fluid secretion and absorption. The current study investigated the role of AQP4 in the formation of hydrocephalus caused by iron overload after IVH. METHODS: There were three parts to this study. First, Sprague-Dawley rats received an intraventricular injection of 100 µl autologous blood or saline control. Second, rats had IVH and were treated with deferoxamine (DFX), an iron chelator, or vehicle. Third, rats had IVH and were treated with 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020), a specific AQP4 inhibitor, or vehicle. Rats underwent T2-weighted and T2* gradient-echo magnetic resonance imaging to assess lateral ventricular volume and intraventricular iron deposition at 7, 14, and 28 days after intraventricular injection and were then euthanized. Real-time quantitative polymerase chain reaction, western blot analysis, and immunofluorescence analyses were conducted on the rat brains to evaluate the expression of AQP4 at different time points. Hematoxylin and eosin-stained brain sections were obtained to assess the ventricular wall damage on day 28. RESULTS: Intraventricular injection of autologous blood caused a significant ventricular dilatation, iron deposition, and ventricular wall damage. There was increased AQP4 mRNA and protein expression in the periventricular tissue in IVH rats through day 7 to day 28. The DFX treatment group had a lower lateral ventricular volume and less intraventricular iron deposition and ventricular wall damage than the vehicle-treated group after IVH. The expression of AQP4 protein in periventricular tissue was also inhibited by DFX on days 14 and 28 after IVH. The use of TGN-020 attenuated hydrocephalus development after IVH and inhibited the expression of AQP4 protein in the periventricular tissue between day 14 and day 28 without a significant effect on intraventricular iron deposition or ventricular wall damage. CONCLUSIONS: AQP4 located in the periventricular area mediated the effect of iron overload on hydrocephalus after IVH.

Satralizumab: A Review in Neuromyelitis Optica Spectrum Disorder.

Satralizumab (Enspryng®) is a monoclonal antibody that blocks the interleukin-6 (IL-6) receptor and is approved for the treatment of neuromyelitis optica spectrum disorder (NMOSD) in patients who are aquaporin-4 immunoglobulin G (AQP4-IgG) seropositive. Patients with NMOSD are at risk of recurrent autoimmune attacks that primarily target the optic nerves and spinal cord but may also target other regions of the central nervous system; these attacks can lead to life-long disability. In the randomized, placebo-controlled phase III SAkuraSky and SAkuraStar trials, subcutaneous satralizumab as an add-on to immunosuppressive therapy or as a monotherapy, respectively, significantly reduced the risk of relapse compared with placebo in patients who were AQP4-IgG seropositive with NMOSD. Satralizumab was well tolerated; the most common adverse events were infection, headache, arthralgia, decreased white blood cell count, hyperlipidaemia and injection-related reactions. In the EU, satralizumab is the first IL-6 receptor blocker to be approved for treatment of AQP4-IgG-seropositive patients with NMOSD, has the potential advantage of subcutaneous administration, and is the only targeted treatment approved for adolescent patients with this disorder. Thus, satralizumab is a valuable treatment option for patients with NMOSD.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disorder, in which recurrent attacks by the body's own immune system can cause severe morbidity and disability. Immunoglobulin G antibodies targeting the aquaporin-4 (AQP4-IgG) water channel in cells of the central nervous system can be detected in the majority of patients with NMOSD. Satralizumab (Enspryng^®), which is designed to suppress autoantibody production by blocking the interleukin-6 (IL-6) receptor, was found to significantly reduce the rate of immune attack recurrence compared with placebo when used as an add-on to standard immunosuppressive therapy (SAkuraSky trial) or when used alone (SAkuraStar trial). Satralizumab was well tolerated in the SAkuraSky and SAkuraStar trials, with infections (e.g. nasopharyngitis, upper respiratory tract infections) being the most common associated adverse event. In the EU, satralizumab is the first IL-6 receptor blocker approved for AQP4-IgG-seropositive patients with NMOSD and is the only subcutaneously administration targeted drug approved for NMOSD. Therefore, satralizumab represents a valuable treatment option for NMOSD.

Molecular mechanism of cerebral edema improvement via IL-1RA released from the stroke-unaffected hindlimb by treadmill exercise after cerebral infarction in rats.

Cerebral edema following cerebral infarction can be severe and directly affect mortality and mobility. Exercise therapy after cerebral infarction is an effective therapeutic approach; however, the molecular mechanism remains unclear. Myokines such as interleukin-1 receptor antagonist (IL-1RA) are released during skeletal muscle contraction with effects on other organs. We hypothesized that myokine release during exercise might improve brain edema and confirmed the hypothesis using transient middle cerebral artery occlusion (tMCAO) model rats. Rats subjected to tMCAO were divided according to the severity of illness and further assigned to exercise and non-exercise groups. Treadmill exercises were performed at a speed of 2-8 m/min for 10 min from 1-6 days post-reperfusion after tMCAO. Exercise significantly reduced edema and neurological deficits in severely ill rats, with a reduction in aquaporin-4 (AQP4) expression in the ischemic core and increased blood IL-1RA release from the stroke-unaffected hindlimb muscle after tMCAO. Administration of IL-1RA into the lateral ventricles significantly reduced edema and AQP4 expression in the ischemic core. In conclusion, treadmill exercise performed in the early phase of stroke onset alleviated the decrease in blood IL-1RA following ischemic stroke. IL-1RA administration decreased astrocytic AQP4 expression in the ischemic core, suppressing brain edema.

Aligning payer and provider strategies with the latest evidence to optimize clinical outcomes for patients with neuromyelitis optica spectrum disorder.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disorder affecting the central nervous system that is associated with significant morbidity and mortality. Early diagnosis and treatment are essential to minimize long-term disability. Recent advances in the understanding of the pathophysiology of NMOSD have led to multiple new therapies, but significant care and knowledge gaps persist. OBJECTIVES: To summarize current knowledge about the burden of disease and diagnosis and treatment of NMOSD in order to support managed care professionals and health care providers in making collaborative, evidence-based decisions to optimize outcomes among patients with NMOSD. In addition, this review also presents findings of a patient survey that provides insight into real-world experiences of those living with NMOSD. SUMMARY: Diagnosis of NMOSD is based on detection of immunoglobulin G antibodies to the water channel protein aquaporin-4 (AQP4-IgG) in the context of compatible clinical and magnetic resonance imaging features. Patients who are AQP4-IgG seronegative and/or who are positive for myelin oligodendrocyte glycoprotein antibodies may also satisfy criteria for NMOSD. The rarity of the condition combined with the significant overlap in clinical features with other autoimmune diseases affecting the central nervous system, most notably multiple sclerosis, can delay accurate diagnosis, which in turn can delay appropriate treatment, leading to the accumulation of long-term disability. Accumulating disability associated with NMOSD has a substantial negative impact on quality of life. The disease typically evolves as relapsing (ie, repeated) acute attacks. Treatment consists of management of acute attacks, prevention of subsequent attacks, and management of acute and chronic symptoms. The armamentarium of therapies to prevent attacks consists of several monoclonal antibodies (mAbs) approved to treat AQP4-IgG-seropositive disease and several off-label therapies used for patients with either seropositive or seronegative disease. There is limited evidence to guide treatment decision-making, including which therapies to use first line, when to switch, and when to use monotherapy vs combination therapy. In addition, therapies with the greatest demonstrated safety and efficacy in NMOSD are costly and may not be accessible to all patients. Moreover, the results of the patient survey revealed significant clinical and financial burdens to patients with NMOSD including frequent attacks, delays in therapy initiation, need for urgent care and repeat hospitalizations, new and worsening symptoms, accumulating disability, and difficulties affording care. As such, key stakeholders must weigh them against the substantial economic costs of untreated or suboptimal treatment of disease. DISCLOSURES: Dr Wingerchuk has served on the advisory board or panel for Alexion, Biogen, Genentech, Horizon, Mitsubishi Tanabe, Novartis, Roche, UCB, and Viela Bio and has received grants of research support from Alexion. Dr Weinshenker has served as a consultant or on the advisory board or panel for Alexion, Genentech, Horizon, Mitsubishi Tanabe, Roche, UCB, and Viela Bio, served on the speakers bureau or other promotional education for Genentech and Roche, and has received royalties from RSR Ltd.

Inebilizumab: A Review in Neuromyelitis Optica Spectrum Disorder.

Inebilizumab (Uplizna®) is a recently approved monoclonal antibody for use in adults with neuromyelitis optica spectrum disorder (NMOSD) who are anti-aquaporin-4 (AQP4) antibody seropositive. Inebilizumab targets the B cell antigen CD19 and effectively depletes circulating B cells, thus suppressing inflammatory NMOSD attacks that are potentially disabling or life-threatening. It is approved as an intravenous infusion in several countries. In the pivotal phase 2/3 N-MOmentum trial, inebilizumab reduced the risk of NMOSD attacks compared with placebo, including in AQP4-antibody seropositive patients. Inebilizumab also significantly reduced the risk of disability score worsening, the number of NMOSD-related hospitalisations and MRI lesion count, but had no significant effect on low-contrast binocular vision. The treatment effect on relapse risk and disability scores was sustained in inebilizumab-treated patients for ≥ 4 years during the open-label extension. Inebilizumab was generally well tolerated, with the most common adverse events being urinary tract infection and arthralgia. Thus, inebilizumab is an effective treatment option for adults with AQP4-antibody seropositive NMOSD.

Neuromyelitis optica spectrum disorder (NMOSD) is a chronic condition denoted by relapsing autoimmune attacks affecting the central nervous system, which may lead to accruing disability or death. It is frequently associated with anti-aquaporin-4 (AQP4) autoantibodies. In recent years, three new monoclonal antibody therapies have gained regulatory approval for the treatment of NMOSD. Inebilizumab (Uplizna®), a monoclonal antibody that targets B cells, is approved for use in AQP4-antibody seropositive adults as an intravenous infusion. Inebilizumab was effective at preventing NMOSD relapse compared with placebo in a pivotal phase 2/3 trial. It also prevented worsening of disability scores, and decreased the number of NMOSD-related hospitalisations and MRI lesions, but did not significantly improve low-contrast binocular vision. The clinical benefit of inebilizumab was maintained long-term (≥ 4 years in the open-label extension). Inebilizumab was generally well tolerated, with most adverse events being mild to moderate in severity. The most common adverse events were urinary tract infection and joint pain. Inebilizumab provides an effective option for preventing NMOSD attacks in adults who are AQP4-antibody seropositive.

Clinical features of organizing pneumonia in anti-aquaporin-4 antibody-positive neuromyelitis optica spectrum disorders.

BACKGROUND: Anti-aquaporin-4 (AQP4) antibody is an autoantibody marker often observed in patients with neuromyelitis optica spectrum disorder (NMOSD). The pathological relevance of complicated pulmonary disorders in anti-AQP4 antibody-positive NMOSD remains unclear. We aimed to assess the clinical and histological relevance of complicated pulmonary disorders in anti-AQP4 antibody-positive NMOSD. METHODS: We retrospectively reviewed the medical records of 52 patients with anti-AQP4 antibody-positive NMOSD and conducted immunohistochemical evaluations of the lung biopsy specimens. RESULTS: Among 52 patients with anti-AQP4 antibody-positive NMOSD, 4 patients showed pulmonary involvement with a diagnosis of organizing pneumonia (OP). The proportion of males was larger (75% vs. 12.5%; p = 0.013) and creatine kinase levels were higher (458.3 U/L vs. 83.9 U/L; p = 0.003) in patients with OP than in those without OP. OP development preceded or coincided with the NMOSD symptoms. Chest computed tomography findings were consistent with OP in all four patients. Bronchoalveolar lavage fluid predominantly contained lymphocytes. Transbronchial lung biopsy revealed intraluminal plugs of inflammatory debris within the alveoli. Alveolar epithelial cells covering the OP lesions exhibited AQP4 loss, immunoglobulin G deposition, and complement activation. Corticosteroid treatment resulted in clinical improvement of OP. CONCLUSION: OP may be considered a pulmonary manifestation of anti-AQP4 antibody-positive NMOSD beyond the central nervous system. Complement-dependent cytotoxicity of the lung epithelial cells caused by anti-AQP4 antibody is at least partly involved in OP development. When diagnosing NMOSD, the possibility of OP should be carefully evaluated based on the detailed history and chest imaging findings.

Immuno-pathogenesis of neuromyelitis optica and emerging therapies.

Neuromyelitis optica (NMO) is an inflammatory disease that resembles MS in the relapsing clinical course of optic neuritis and myelitis. Two decades of studies have revealed that autoantibodies, reactive to the water channel protein aquaporin 4 (AQP4) are detected in the core group of patients. These autoantibodies play a crucial role in the inflammatory pathology of NMO, involving proinflammatory cytokines, chemokines, and various inflammatory cells such as Th17 cells. Anti-AQP4 antibody-positive NMO differs fundamentally from MS, particularly in the responsiveness to therapies and the neuropathology accompanying destruction of astrocytes. Research into the immunological mechanism has led to the identification of possible targets of therapy, including complement pathway and interleukin-6 (IL-6) receptor signaling. Recent randomized controlled clinical trials have shown the remarkable efficacy of antibodies specific for complement C5, IL-6 receptor, and CD19+ B cells in prevention of NMO spectrum disorder relapses, although no such effects were found in anti-AQP4 antibody-negative patients. These results imply that anti-AQP4 antibody is a biomarker predicting the efficacy of therapies, and indicate the future direction towards "precision medicine."

Neuromyelitis Optica and Skin.

Neuromyelitis optica spectrum disorder is characterized by attacks of optic neuritis and/or longitudinally extensive transverse myelitis and the presence of anti-aquaporin-4 autoantibodies. Most relapses of neuromyelitis optica worsen over days and then slowly improve in the weeks or months after the maximum clinical deficit has been reached. However, recovery is usually incomplete. The diagnosis of the disease and attacks must be made as early as possible and require emergency treatment. Dermatologists can play a role in achieving this end. Neuropathic pruritus is common and can be used to diagnose neuromyelitis optica. Hence, the association of pruritus with optic neuropathy and some symptoms of transverse myelitis strongly suggest this diagnosis. Many autoimmune diseases can sometimes be associated with neuromyelitis optica. Patients with newly diagnosed skin infections or sexually transmitted diseases need to be informed that these infections could trigger a relapse of neuromyelitis optica.

Population Pharmacokinetic Modeling of Inebilizumab in Subjects with Neuromyelitis Optica Spectrum Disorders, Systemic Sclerosis, or Relapsing Multiple Sclerosis.

BACKGROUND AND OBJECTIVE: Inebilizumab is a humanized, affinity-optimized, afucosylated immunoglobulin (Ig)-G1κ monoclonal antibody that binds to CD19, resulting in effective depletion of peripheral B cells. It is being developed to treat various autoimmune diseases, including neuromyelitis optica spectrum disorders (NMOSD), systemic sclerosis (SSc), and relapsing multiple sclerosis (MS). METHODS: Pharmacokinetic data from a pivotal study in adult subjects with NMOSD and two early-stage studies in subjects with SSc or relapsing MS were pooled and simultaneously analyzed using a population approach. RESULTS: Upon intravenous administration, the pharmacokinetics of inebilizumab were adequately described by a two-compartment model with parallel first-order and time-dependent nonlinear elimination pathways. An asymptotic nonlinear elimination suggests that inebilizumab undergoes receptor (CD19)-mediated clearance. The estimated systemic clearance (CL) of the first-order elimination pathway (0.188 L/day) and the volume of distribution (Vd) (5.52 L) were typical for therapeutic immunoglobulins. The elimination half-life was approximately 18 days. The maximum velocity (Vmax) of the nonlinear elimination pathway decreased with time, presumably due to the depletion of B cells upon inebilizumab administration. As for other therapeutic monoclonal antibodies, the CL and Vd of inebilizumab increased with body weight. CONCLUSIONS: The presence of antidrug antibodies, status of hepatic or renal function, and use of small-molecule drugs commonly used by subjects with NMOSD had no clinically relevant impact on the pharmacokinetics of inebilizumab. The nonlinear elimination pathway at the 300 mg therapeutic dose level is not considered clinically relevant.

Inebilizumab-cdon: USFDA Approved for the Treatment of NMOSD (Neuromyelitis Optica Spectrum Disorder).

Inebilizumab-cdon (Uplizna™) was currently approved by the United States Food and Drug Administration (USFDA) for the treatment of NMOSD (neuromyelitis optica spectrum disorder). It was developed by Viela Bio (Nasdaq: VIE) USA. Inebilizumab-cdon (formerly MEDI-551) is a humanized antibody, which induces CD19 + B cell depletion by increasing antibody-dependent cell cytotoxicity (ADCC) and cell phagocytosis (ADCP) of effector cells. Various clinical trials exhibit its safe and effective pharmacokinetic and pharmacodynamic profile. In June 2019, Viela Bio submitted Biologics License Application (BLA) to the FDA based on the findings obtained from the N-Momentum trial. This article summarizes the milestones in the development of Inebilizumab-cdon leading to this approval for the treatment of advanced NMOSD.

Effects of aquaporin 4 and inward rectifier potassium channel 4.1 on medullospinal edema after methylprednisolone treatment to suppress acute spinal cord injury in rats.

PURPOSE: To investigate the effects of aquaporin 4 (AQP4) and inward rectifier potassium channel 4.1 (Kir4.1) on medullospinal edema after treatment with methylprednisolone (MP) to suppress acute spinal cord injury (ASCI) in rats. METHODS: Sprague Dawley rats were randomly divided into control, sham, ASCI, and MP-treated ASCI groups. After the induction of ASCI, we injected 30 mg/kg MP via the tail vein at various time points. The Tarlov scoring method was applied to evaluate neurological symptoms, and the wet-dry weights method was applied to measure the water content of the spinal cord. RESULTS: The motor function score of the ASCI group was significantly lower than that of the sham group, and the spinal water content was significantly increased. In addition, the levels of AQP4 and Kir4.1 were significantly increased, as was their degree of coexpression. Compared with that in the ASCI group, the motor function score and the water content were significantly increased in the MP group; in addition, the expression and coexpression of AQP4 and Kir4.1 were significantly reduced. CONCLUSION: Methylprednisolone inhibited medullospinal edema in rats with acute spinal cord injury, possibly by reducing the coexpression of aquaporin 4 and Kir4.1 in medullospinal tissues.

Effects of aquaporin 4 and inward rectifier potassium channel 4 1 on medullospinal edema after methylprednisolone treatment to suppress acute spinal cord injury in rat

Abstract Purpose: To investigate the effects of aquaporin 4 (AQP4) and inward rectifier potassium channel 4.1 (Kir4.1) on medullospinal edema after treatment with methylprednisolone (MP) to suppress acute spinal cord injury (ASCI) in rats. Methods: Sprague Dawley rats were randomly divided into control, sham, ASCI, and MP-treated ASCI groups. After the induction of ASCI, we injected 30 mg/kg MP via the tail vein at various time points. The Tarlov scoring method was applied to evaluate neurological symptoms, and the wet-dry weights method was applied to measure the water content of the spinal cord. Results: The motor function score of the ASCI group was significantly lower than that of the sham group, and the spinal water content was significantly increased. In addition, the levels of AQP4 and Kir4.1 were significantly increased, as was their degree of coexpression. Compared with that in the ASCI group, the motor function score and the water content were significantly increased in the MP group; in addition, the expression and coexpression of AQP4 and Kir4.1 were significantly reduced. Conclusion: Methylprednisolone inhibited medullospinal edema in rats with acute spinal cord injury, possibly by reducing the coexpression of aquaporin 4 and Kir4.1 in medullospinal tissues.

Enzymatic deglycosylation converts pathogenic neuromyelitis optica anti-aquaporin-4 immunoglobulin G into therapeutic antibody.

OBJECTIVE: Neuromyelitis optica (NMO) is caused by binding of pathogenic autoantibodies (NMO-immunoglobulin G [IgG]) to aquaporin-4 (AQP4) on astrocytes, which initiates complement-dependent cytotoxicity (CDC) and inflammation. We recently introduced mutated antibody (aquaporumab) and small-molecule blocker strategies for therapy of NMO, based on prevention of NMO-IgG binding to AQP4. Here, we investigated an alternative strategy involving neutralization of NMO-IgG effector function by selective IgG heavy-chain deglycosylation with bacteria-derived endoglycosidase S (EndoS). METHODS: Cytotoxicity and NMO pathology were measured in cell and spinal cord slice cultures, and in mice exposed to control or EndoS-treated NMO-IgG. RESULTS: EndoS treatment of NMO patient serum reduced by >95% CDC and antibody-dependent cell-mediated cytotoxicity, without impairment of NMO-IgG binding to AQP4. Cytotoxicity was also prevented by addition of EndoS after NMO-IgG binding to AQP4. The EndoS-treated, nonpathogenic NMO-IgG competitively displaced pathogenic NMO-IgG bound to AQP4, and prevented NMO pathology in spinal cord slice culture and mouse models of NMO. INTERPRETATION: EndoS deglycosylation converts pathogenic NMO-IgG autoantibodies into therapeutic blocking antibodies. EndoS treatment of blood may be beneficial in NMO, and may be accomplished, for example, by therapeutic apheresis using surface-immobilized EndoS.

Treatment of neuromyelitis optica: an evidence based review.

Neuromyelitis optica (NMO) is an inflammatory disease of the central nervous system characterized by severe optic neuritis and transverse myelitis, usually with a relapsing course. Aquaporin-4 antibody is positive in a high percentage of NMO patients and it is directed against this water channel richly expressed on foot processes of astrocytes. Due to the severity of NMO attacks and the high risk for disability, treatment should be instituted as soon as the diagnosis is confirmed. There is increasing evidence that NMO patients respond differently from patients with multiple sclerosis (MS), and, therefore, treatments for MS may not be suitable for NMO. Acute NMO attacks usually are treated with high dose intravenous corticosteroid pulse and plasmapheresis. Maintenance therapy is also required to avoid further attacks and it is based on low-dose oral corticosteroids and non-specific immunosuppressant drugs, like azathioprine and mycophenolate mofetil. New therapy strategies using monoclonal antibodies like rituximab have been tested in NMO, with positive results in open label studies. However, there is no controlled randomized trial to confirm the safety and efficacy for the drugs currently used in NMO.

Potential utility of aquaporin modulators for therapy of brain disorders.

Of the several aquaporin (AQP) water channels expressed in the central nervous system, AQP4 is an attractive target for drug discovery. AQP4 is expressed in astroglia, most strongly at the blood-brain and brain-cerebrospinal fluid barriers. Phenotype analysis of AQP4 knockout mice indicates the involvement of AQP4 in three distinct processes: brain water balance, astroglial cell migration and neural signal transduction. By slowing water uptake into the brain, AQP4 knockout mice manifest reduced brain swelling and improved outcome in models of cytotoxic cerebral oedema such as water intoxication, focal ischaemia and meningitis. However, by slowing the clearance of excess water from brain, AQP4 knockout mice do worse in models of vasogenic oedema such as brain tumour, abscess and hydrocephalus. AQP4 deficient astroglial cells show greatly impaired migration in response to chemotactic stimuli, reducing glial scar formation, by a mechanism that we propose involves AQP4-facilitated water flux in lamellipodia of migrating cells. AQP4 knockout mice also manifest increased seizure threshold and duration, by a mechanism that may involve slowed K(+) uptake from the extracellular space (ECS) following neuroexcitation, as well as ECS expansion. Notwithstanding challenges in drug delivery to the central nervous system and their multiplicity of actions, AQP4 inhibitors have potential utility in reducing cytotoxic brain swelling, increasing seizure threshold and reducing glial scar formation; enhancers of AQP4 expression have potential utility in reducing vasogenic brain swelling. AQP4 modulators may thus offer new therapeutic options for stroke, tumour, infection, hydrocephalus, epilepsy and traumatic brain and spinal cord injury.