Minshu Li

Responsiveness to reduced dosage of rituximab in Chinese patients with neuromyelitis optica.

Objective: To determine the effect of a lower dose of rituximab in depleting B lymphocytes, maintaining low B-cell counts, and relapse in patients with neuromyelitis optica (NMO) and NMO spectrum disorders. Methods: We treated 5 Chinese patients with deteriorating NMO and NMO spectrum disorders with a 100-mg IV infusion of rituximab once a week for 3 consecutive weeks, followed by additional infusion of the same dosage depending on circulating B-cell repopulation. Results: This reduced dosage of rituximab was sufficient to deplete B cells and maintain low B-cell counts. None of the treated patients experienced relapse, and all patients exhibited stabilized or improved neurologic function during the 1-year follow-up period. MRI revealed the absence of new lesions, no enhancement in spinal cord and brain, a significant shrinkage of spinal cord segments, and a reduction/disappearance of previous brain lesions. Conclusion: A lower dosage of rituximab may be sufficient in depleting B cells, maintaining low B-cell counts, and preventing disease progression in Chinese patients with NMO.

Clinical Features and Sera Anti-Aquaporin 4 Antibody Positivity in Patients with Demyelinating Disorders of the Central Nervous System from Tianjin, China

To investigate the clinical characteristics and sera anti‐aquaporin 4 (AQP4) antibody positivity in patients with inflammatory demyelinating disorders (IDDs) of the central nervous system (CNS) in Tianjin, China.

Autoantibody to MOG suggests two distinct clinical subtypes of NMOSD

We characterized a unique group of patients with neuromyelitis optica spectrum disorder (NMOSD) who carried autoantibodies of aquaporin-4 (AQP4) and myelin-oligodendrocyte glycoprotein (MOG). Among the 125 NMOSD patients, 10 (8.0%) were AQP4- and MOG-ab double positive, and 14 (11.2%) were MOG-ab single positive. The double-positive patients had a multiphase disease course with a high annual relapse rate (P=0.0431), and severe residual disability (P>0.0001). Of the double- positive patients, 70% had MS-like brain lesions, more severe edematous, multifocal regions on spinal magnetic resonance imaging (MRI), pronounced decreases of retinal nerve fiber layer thickness and atrophy of optic nerves. In contrast, patients with only MOG-ab had a higher ratio of monophasic disease course and mild residual disability. Spinal cord MRI illustrated multifocal cord lesions with mild edema, and brain MRIs showed more lesions around lateral ventricles. NMOSD patients carrying both autoantibodies to AQP4 and MOG existed and exhibited combined features of prototypic NMO and relapsing- remitting form of MS, whereas NMOSD with antibodies to MOG only exhibited an “intermediate” phenotype between NMOSD and MS. Our study suggests that antibodies against MOG might be pathogenic in NMOSD patients and that determination of anti-MOG antibodies maybe instructive for management of NMOSD patients.

Selective NLRP3 (Pyrin Domain–Containing Protein 3) Inflammasome Inhibitor Reduces Brain Injury After Intracerebral Hemorrhage

Background and Purpose— Intracerebral hemorrhage (ICH) is a devastating disease without effective treatment. As a key component of the innate immune system, the NOD-like receptor (NLR) family, NLRP3 (pyrin domain–containing protein 3) inflammasome, when activated after ICH, promotes neuroinflammation and brain edema. MCC950 is a potent, selective, small-molecule NLRP3 inhibitor that blocks NLRP3 activation at nanomolar concentrations. Here, we examined the effect of MCC950 on brain injury and inflammation in 2 models of ICH in mice. Methods— In mice with ICH induced by injection of autologous blood or bacterial collagenase, we determined the therapeutic potential of MCC950 and its mechanisms of neuroprotection. Results— MCC950 reduced IL-1&bgr; (interleukin-1&bgr;) production and attenuated neurodeficits and perihematomal brain edema after ICH induction by injection of either autologous blood or collagenase. In mice with autologous blood-induced ICH, the protection of MCC950 was associated with reduced leukocyte infiltration into the brain and microglial production of IL-6. MCC950 improved blood–brain barrier integrity and diminished cell death. Notably, the protective effect of MCC950 was abolished in mice depleted of either microglia or Gr-1+ myeloid cells. Conclusions— These results indicate that the NLRP3 inflammasome inhibitor, MCC950, attenuates brain injury and inflammation after ICH. Hence, NLRP3 inflammasome inhibition is a potential therapy for ICH that warrants further investigation.

Alterations of natural killer cells in traumatic brain injury

To investigate the relationship between natural killer (NK) cells and traumatic brain injury (TBI), we tracked an established phenotype of circulating NK cells at several time points in patients with different grades of TBI. In serial peripheral blood samples, NK cells were prospectively measured by flow cytometry of CD3− CD56+ lymphocytes. Compared to healthy controls, TBI patients had reductions in both the percentage and the absolute number of NK cells. Furthermore, the magnitude of NK cell reduction correlated with the degree of TBI severity at several time points. That is, NK cell population size was independently associated with lower Glasgow Coma Scale scores. In addition, at some time points, a positive correlation was found between the NK cell counts and Glasgow Outcome Scale scores. Our results indicate that TBI induces a reduction in the number of NK cells, and the magnitude of the reduction appears to parallel the severity of TBI.

Glatiramer acetate ameliorates experimental autoimmune neuritis

Glatiramer acetate (GA) is one of the first‐line disease‐modifying medications that have been approved for the treatment of multiple sclerosis via immune modulatory mechanisms. However, it remains unclear whether the immunomodulation effect of GA is central nervous system (CNS) antigen specific. Here, we explored the mechanism of action of GA by subcutaneously injecting GA in experimental autoimmune neuritis (EAN) rats, an animal model for Guillain–Barré syndrome (GBS). Clinical, electrophysiological and histological findings showed that neurological deficits, demyelination and axonal injury of sciatic nerves were all significantly attenuated in Lewis rats when GA was administered before immunization with peripheral nervous system antigen P0. Our results further demonstrated that GA treatment inhibited either P0 or myelin basic protein (MBP) (CNS antigen)‐stimulated auto‐immune T‐cell proliferation in vitro. GA administrated at 10 days after induction of EAN when neurological sign became apparent also ameliorated the severity of disease, inhibited T‐cell response to P0 and MBP and induced shift of proinflammatory and immune modulatory cytokines. Collectively, our findings suggested that GA attenuated neurological deficits in EAN rats and that the immune modulatory mechanisms of GA were not CNS antigen specific.

Quantitative analysis of aquaporin-4 antibody in longitudinally extensive transverse myelitis

Aquaporin-4 (AQP-4) antibody-positive longitudinally extensive transverse myelitis (LETM) is referred to as a neuromyelitis optica (NMO) spectrum disorder. We conducted an exploratory investigation of correlations between AQP-4 antibody serum levels, as determined by a fluorescent immunoprecipitation assay, and clinical characteristics in LETM. Expanded Disability Status Scores (EDSS) scores and number of segments of spinal cord involved were positively correlated to AQP-4 antibody levels. However, serum AQP-4 antibody levels were not correlated with the time to next attack or the conversion time of LETM to NMO, although seropositive LETM patients demonstrated a high conversion rate to NMO (78.1%).

DRα1-MOG-35-55 treatment reduces lesion volumes and improves neurological deficits after traumatic brain injury

Traumatic brain injury (TBI) results in severe neurological impairments without effective treatments. Inflammation appears to be an important contributor to key pathogenic events such as secondary brain injury following TBI and therefore serves as a promising target for novel therapies. We have recently demonstrated the ability of a molecular construct comprised of the human leukocyte antigen (HLA)-DRα1 domain linked covalently to mouse (m)MOG-35-55 peptide (DRα1-MOG-35-55 construct) to reduce CNS inflammation and tissue injury in animal models of multiple sclerosis and ischemic stroke. The aim of the current study was to determine if DRα1-MOG-35-55 treatment of a fluid percussion injury (FPI) mouse model of TBI could reduce the lesion size and improve disease outcome measures. Neurodeficits, lesion size, and immune responses were determined to evaluate the therapeutic potential and mechanisms of neuroprotection induced by DRα1-MOG-35-55 treatment. The results demonstrated that daily injections of DRα1-MOG-35-55 given after FPI significantly reduced numbers of infiltrating CD74+ and CD86+ macrophages and increased numbers of CD206+ microglia in the brain concomitant with smaller lesion sizes and improvement in neurodeficits. Conversely, DRα1-MOG-35-55 treatment of TBI increased numbers of circulating CD11b+ monocytes and their expression of CD74 but had no detectable effect on cell numbers or marker expression in the spleen. These results demonstrate that DRα1-MOG-35-55 therapy can reduce CNS inflammation and significantly improve histological and clinical outcomes after TBI. Future studies will further examine the potential of DRα1-MOG-35-55 for treatment of TBI.

Depletion of microglia augments the dopaminergic neurotoxicity of MPTP

The activation of microglia and the various substances they produce have been linked to the pathologic development of Parkinsons disease (PD), but the precise role of microglia in PD remains to be defined. The survival of microglia depends on colony‐stimulating factor 1 receptor (CSF1R) signaling, and CSF1R inhibition results in rapid elimination of microglia in the central nervous system. Using a mouse PD model induced by 1‐methyl‐4‐phenyl‐1, 2, 3, 6‐tetrahydropyridine (MPTP) treatment, we showed that the depletion of microglia via the CSF1R inhibitor PLX3397 exacerbated the impairment of locomotor activities and the loss of dopaminergic neurons. Further, depletion of microglia augmented the production of inflammatory mediators and infiltration of leukocytes in the brain after MPTP exposure. Microglia depletion‐induced aggravation of MPTP neurotoxicity was also seen in lymphocyte‐deficient mice. In addition, the depletion of microglia did not affect the production of brain‐derived neurotrophic factor, but it dramatically augmented the production of inflammatory mediators by astrocytes after MPTP treatment. Our findings suggest microglia play a protective role against MPTP‐induced neuroinflammation and dopaminergic neurotoxicity.—Yang, X., Ren, H., Wood, K., Li, M., Qiu, S., Shi, F.‐D., Ma, C., Liu, Q. Depletion of microglia augments the dopaminergic neurotoxicity of MPTP. FASEB J. 32, 3336–3345 (2018). www.fasebj.org

Upregulation of CD74 and its potential association with disease severity in subjects with ischemic stroke

ABSTRACT Macrophage migration inhibitory factor (MIF) is a key cytokine/chemokine in the activation and recruitment of inflammatory T lymphocytes known to exacerbate experimental stroke severity. MIF effects are mediated through its primary cellular receptor, CD74, the MHC class II invariant chain present on all class II expressing cells, including monocytes, macrophages and dendritic cells (DC). We demonstrated previously that partial MHC class II/peptide constructs (pMHC) can effectively treat mice with experimental stroke, in part through their ability to competitively inhibit MIF/CD74 interactions and downstream signaling. However, the role of MIF and CD74 in human ischemic stroke is not yet well established. To evaluate the therapeutic potential for pMHC, we assessed MIF and CD74 expression levels and their association with disease outcome in subjects with ischemic stroke. MIF levels were assessed in blood plasma by ELISA and CD74 expression was quantified by flow cytometry and qRT‐PCR in peripheral blood mononuclear cells (PBMCs) obtained from subjects with ischemic stroke and age and sex‐matched healthy controls (HC). MIF levels were increased in plasma and the number of CD74+ cells and CD74 mRNA expression levels were significantly increased in PBMC of subjects with ischemic stroke versus HC, mainly on CD4+ T cells, monocytes and DC. Greater increases of CD74+ cells were seen in subjects with cortical vs. subcortical infarcts and the number of CD74+ cells in blood correlated strongly with infarct size and neurological outcomes. However, differences in MIF and CD74 expression were not affected by age, gender or lesion laterality. Increased CD74 expression levels may serve as a useful biomarker for worse stroke severity and predicted outcomes in subjects with ischemic stroke and provide a rationale for potential future treatment with pMHC constructs. HIGHLIGHTSBoth MIF and CD74 levels were increased in subjects with ischemic stroke.Higher CD74 levels occurred mainly on CD4+ T cells, monocytes and dendritic cells.CD74+ cells were higher in stroke subjects with cortical vs. subcortical infarcts.CD74+ cells in blood correlated with infarct size and neurologic outcomes.CD74 expression levels may serve as a useful biomarker for new stroke therapies.