Lipocalin 2 is a novel immune mediator of experimental autoimmune encephalomyelitis pathogenesis and is modulated in multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE) is a widely used animal model of multiple sclerosis (MS), an inflammatory, demyelinating disease of the central nervous system (CNS). EAE pathogenesis involves various cell types, cytokines, chemokines, and adhesion molecules. Given the complexity of the inflammatory response in EAE, it is likely that many immune mediators still remain to be discovered. To identify novel immune mediators of EAE pathogenesis, we performed an Affymetrix gene array screen on the spinal cords of mice at the onset stage of disease. This screening identified the gene encoding lipocalin 2 (Lcn2) as being significantly upregulated. Lcn2 is a multi-functional protein that plays a role in glial activation, matrix metalloproteinase (MMP) stabilization, and cellular iron flux. As many of these processes have been implicated in EAE, we characterized the expression and role of Lcn2 in this disease in C57BL/6 mice. We show that Lcn2 is significantly upregulated in the spinal cord throughout EAE and is expressed predominantly by monocytes and reactive astrocytes. The Lcn2 receptor, 24p3R, is also expressed on monocytes, macrophages/microglia, and astrocytes in EAE. In addition, we show that EAE severity is increased in Lcn2(-/-) mice as compared with wild-type controls. Finally, we demonstrate that elevated levels of Lcn2 are detected in the plasma and cerebrospinal fluid (CSF) in MS and in immune cells in CNS lesions in MS tissue sections. These data indicate that Lcn2 is a modulator of EAE pathogenesis and suggest that it may also play a role in MS.     

Serum pro-inflammatory and anti-inflammatory cytokines and the pathogenesis of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) as an experimental model of multiple sclerosis (MS) is characterized by demyelination, infiltration of inflammatory cells into the nervous system and dysregulation of serum inflammatory cytokines. We investigated the correlation of serum cytokines and other inflammatory markers with the EAE pathogenesis. After EAE induction, the levels of different serum cytokine/inflammatory mediators were measured. Furthermore, motor functions, myelination, and lymphocyte infiltration in EAE mice were also assessed. Our results revealed that the serum concentrations of T-helper 1 (Th1) and Th17 cytokines, interleukin (IL)-6, IL-1β, IL-1α and prostaglandin E2 in EAE mice were significantly higher than controls. The ratios of pro- to anti-inflammatory cytokines were different between the EAE and the control group. A statistically significant positive correlation was found between the IL-6/IL-10 ratio and the EAE severity, demyelination rate, and lymphocyte infiltration in EAE mice. Results indicate that the profiles of serum pro- and anti-inflammatory cytokines might be useful as biomarkers for monitoring the pathological manifestation of EAE. Furthermore, evaluating the dynamic interplay of serum cytokine levels and the correlation with pathogenic mechanisms of EAE may provide diagnostic and therapeutic insights for MS and some other inflammatory disorders.     

Apoferritin attenuates experimental allergic encephalomyelitis in SJL mice

Ferritin has been shown to attenuate iron-catalyzed oxidative damage in several experimental conditions. Since oxidative damage has been implicated in the pathogenesis of multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE), an animal model of MS, we tested the hypothesis that ferritin would act to attenuate disease. The experimental design was to increase plasma ferritin levels during the active stage of EAE by giving systemic injections of apoferritin and then compare disease activity between these mice and EAE mice administered vehicle. Additional mice received systemic injections of iron, which induces ferritin synthesis, in order to test the effects of exogenous iron on the disease course. Although plasma levels of ferritin were found to be elevated in both apoferritin and iron-injected EAE mice, only apoferritin treatment resulted in a reduction in disease activity compared to EAE mice given vehicle. The suppressive effects of apoferritin administration suggest that the increase in endogenous ferritin levels that have been previously observed in the cerebrospinal fluid of chronic progressive MS patients with active disease might be functioning to limit the severity and spread of tissue damage.     

Plasticity in reflex pathways to the lower urinary tract following spinal cord injury

The lower urinary tract has two main functions, storage and periodic expulsion of urine, that are regulated by a complex neural control system in the brain and lumbosacral spinal cord. This neural system coordinates the activity of two functional units in the lower urinary tract: (1) a reservoir (the urinary bladder) and (2) an outlet (consisting of bladder neck, urethra and striated muscles of the external urethra sphincter). During urine storage the outlet is closed and the bladder is quiescent to maintain a low intravesical pressure. During micturition the outlet relaxes and the bladder contracts to promote efficient release of urine. This reciprocal relationship between bladder and outlet is generated by reflex circuits some of which are under voluntary control. Experimental studies in animals indicate that the micturition reflex is mediated by a spinobulbospinal pathway passing through a coordination center (the pontine micturition center) located in the rostral brainstem. This reflex pathway is in turn modulated by higher centers in the cerebral cortex that are involved in the voluntary control of micturition. Spinal cord injury at cervical or thoracic levels disrupts voluntary control of voiding as well as the normal reflex pathways that coordinate bladder and sphincter function. Following spinal cord injury the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. However the bladder does not empty efficiently because coordination between the bladder and urethral outlet is lost. Studies in animals indicate that dysfunction of the lower urinary tract after spinal cord injury is dependent in part on plasticity of bladder afferent pathways as well as reorganization of synaptic connections in the spinal cord. Reflex plasticity is associated with changes in the properties of ion channels and electrical excitability of afferent neurons and appears to be mediated in part by neurotrophic factors released in the spinal cord and/or the peripheral target organs.     

Combined treatment with atorvastatin and minocycline suppresses severity of EAE

Multiple sclerosis (MS) is the most common inflammatory demyelinating disorder of the central nervous system (CNS). An approach to improve MS treatment is to identify a rational combination of new medications or existing therapies that impact different aspects of the disease process. Statins are effective in the treatment of MS animal models and are promising candidates for future treatment. Minocycline ameliorates clinical severity of experimental autoimmune encephalomyelitis (EAE) and exhibits several anti-inflammatory and neuroprotective activities. In this study, we tested whether the combination of these two drugs could produce beneficial effects in EAE mice immunized with myelin oligodendrocyte protein (MOG). Our findings show that combined treatment, compared to using the medications alone, resulted in a significant reduction in disease severity, in both the acute and chronic phases of the disease, along with attenuation of inflammation, demyelination and axonal loss. Stereological analysis revealed that the combined treatment significantly guarded against neuroinflammation and neurodegeneration. Moreover, a significant suppression of anti-MOG antibody production in animals treated with the two medications was found. In conclusion, our findings prove that this combination of drugs is neuroprotective and suppresses the severity of EAE. Furthermore, this pharmacological approach appears to be promising as a future therapeutic strategy to control MS.     

Diagnosis and treatment of neurogenic bladder]

Bladder function has two phases, urine storage and urine evacuation which are based on the complex neurological controls including central as well as peripheral nervous system. Therefore, various neurological lesions can cause bladder dysfunctions such as disturbed storage or disturbed urine evacuation. Micturitional symptoms can be divided into storage symptoms and voiding symptoms. Storage symptoms include urgency, frequency of micturition and urinary incontinence, on the other hand voiding symptoms include difficulty in starting micturition, prolonged or intermittent micturition and urinary retention. The pathophysiology of bladder dysfunction is known by performing urodynamic studies such as uroflowmetry, residual urine measurement, cystometry, external urethral sphincter electromyography, pressure-flow study and voiding urethrocystography. The most common cause of storage symptom is detrusor overactivity, which can occurs in the central nervous system disorders. Disturbed voiding can be due to poor relaxation of urethral sphincter or detrusor weekness. The treatment of neurogenic bladder usually can be done by the combination of bladder training, intermittent catheterization and pharmacotherapy. It is very important to try to avoid the bladder overdistension which can cause weak detrusor and poor recovery.     

Urinary Bladder Function and Somatic Sensitivity in Vasoactive Intestinal Polypeptide (VIP)−/− Mice

Vasoactive intestinal polypeptide (VIP) is an immunomodulatory neuropeptide widely distributed in neural pathways that regulate micturition. VIP is also an endogenous anti-inflammatory agent that has been suggested for the development of therapies for inflammatory disorders. In the present study, we examined urinary bladder function and hindpaw and pelvic sensitivity in VIP(-/-) and littermate wildtype (WT) controls. We demonstrated increased bladder mass and fewer but larger urine spots on filter paper in VIP(-/-) mice. Using cystometry in conscious, unrestrained mice, VIP(-/-) mice exhibited increased void volumes and shorter intercontraction intervals with continuous intravesical infusion of saline. No differences in transepithelial resistance or water permeability were demonstrated between VIP(-/-) and WT mice; however, an increase in urea permeability was demonstrated in VIP(-/-) mice. With the induction of bladder inflammation by acute administration of cyclophosphamide, an exaggerated or prolonged bladder hyperreflexia and hindpaw and pelvic sensitivity were demonstrated in VIP(-/-) mice. The changes in bladder hyperreflexia and somatic sensitivity in VIP(-/-) mice may reflect increased expression of neurotrophins and/or proinflammatory cytokines in the urinary bladder. Thus, these changes may further regulate the neural control of micturition.     

Corticotropin-Releasing Hormone from the Pontine Micturition Center Plays an Inhibitory Role in Micturition

Lower urinary tract or voiding disorders are prevalent across all ages and affect >40% of adults over 40 years old, leading to decreased quality of life and high health care costs. The pontine micturition center (PMC; i.e., Barrington''s nucleus) contains a large population of neurons that localize the stress-related neuropeptide, corticotropin-releasing hormone (CRH) and project to neurons in the spinal cord to regulate micturition. How the PMC and CRH-expressing neurons in the PMC control volitional micturition is of critical importance for human voiding disorders. To investigate the specific role of CRH in the PMC, neurons in the PMC-expressing CRH were optogenetically activated during in vivo cystometry in unanesthetized mice of either sex. Optogenetic activation of CRH-PMC neurons led to increased intermicturition interval and voided volume, similar to the altered voiding phenotype produced by social stress. Female mice showed a significantly more pronounced phenotype change compared with male mice. These effects were eliminated by CRH-receptor 1 antagonist pretreatment. Optogenetic inhibition of CRH-PMC neurons led to an altered voiding phenotype characterized by more frequent voids and smaller voided volumes. Last, in a cyclophosphamide cystitis model of bladder overactivity, optogenetic activation of CRH-PMC neurons returned the voiding pattern to normal. Collectively, our findings demonstrate that CRH from PMC spinal-projecting neurons has an inhibitory function on micturition and is a potential therapeutic target for human disease states, such as voiding postponement, urinary retention, and underactive or overactive bladder.SIGNIFICANCE STATEMENT The pontine micturition center (PMC), which is a major regulator of volitional micturition, is neurochemically heterogeneous, and excitatory neurotransmission derived from PMC neurons is thought to mediate the micturition reflex. In the present study, using optogenetic manipulation of CRH-containing neurons in double-transgenic mice, we demonstrate that CRH, which is prominent in PMC-spinal projections, has an inhibitory function on volitional micturition. Moreover, engaging this inhibitory function of CRH can ameliorate bladder hyperexcitability induced by cyclophosphamide in a model of cystitis. The data underscore CRH as a novel target for the treatment of voiding dysfunctions, which are highly prevalent disease processes in children and adults.     

Digitized image analysis reveals diffuse abnormalities in normal-appearing white matter during acute experimental autoimmune encephalomyelitis

Demyelination of the central nervous system is a hallmark of multiple sclerosis and its widely used animal model, experimental autoimmune encephalomyelitis (EAE). Recent studies using magnetic resonance imaging and spectroscopy on multiple sclerosis patients have revealed abnormalities of central nervous system normal-appearing white matter suggesting that micro-demyelination and/ or extensive membrane turnover accompanies and perhaps precedes the appearance of manifest inflammatory lesions. In the present study, we induced EAE in SWXJ mice and analyzed digitized images of immunocytochemically stained spinal cord for detection of myelin proteolipid protein (PLP). We found that digitized image analysis is a highly sensitive, objective methodology for measuring the extent of myelin loss during EAE. Our data show that two-thirds of the measured reduction of myelin PLP occurring in EAE spinal cord could be attributed to a loss of myelin in normal-appearing white matter. The marked decrease in detection of PLP was accompanied by a corresponding decrease in PLP mRNA in the central nervous system. Our results indicate that during acute EAE, diffuse myelin abnormalities extend far beyond visibly detectable inflammatory foci and are characterized by a global decrease in the expression of myelin genes and their encoded proteins. J. Neurosci. Res. 54:364–372, 1998. © 1998 Wiley-Liss, Inc.     

Dysregulation of the hypothalamic-pituitary-gonadal axis in experimental autoimmune encephalomyelitis and multiple sclerosis

The ability of sex hormones to regulate cytokine production is well established, but the ability of cytokines to regulate sex hormone production has only begun to be investigated. We measured sex hormones in mice with passive experimental autoimmune encephalomyelitis (EAE) and in multiple sclerosis (MS) patients with sexual dysfunction. Abnormally low serum testosterone levels were found in male mice with EAE and in male MS patients, while serum estrogen levels in female mice with EAE were normal. An inverse relationship between cytokine and testosterone levels in male mice with EAE, coupled with an increase in serum luteinizing hormone (LH) levels, suggests that inflammatory cytokines suppress testosterone production by a direct effect on testicular Leydig cells. Gender differences in the sensitivity of the hypothalamic–pituitary–gonadal (HPG) axis to inflammation may be an important factor regulating the duration and severity of central nervous system (CNS) autoimmunity.     

Variation in experimental autoimmune encephalomyelitis scores in a mouse model of multiple sclerosis

Multiple sclerosis (MS) is a common demyelinating central nervous system disease associated with progressive physical impairment. To study the mechanism underlying disease pathogenesis and develop potential treatments, experimental autoimmune encephalomyelitis (EAE) is often used as an animal model. EAE can be induced in various species by introducing specific antigens, which ultimately result in motor dysfunction. Although the severity of the paralysis is indicated using the EAE score, there is no standard scoring system for EAE signs, and there is variability between research groups with regard to the exact EAE scoring system utilized. Here, we describe the criteria used for EAE scoring systems in various laboratories and suggest combining EAE score with another quantitative index to evaluate paralysis, such as the traveled distance, with the goal of facilitating the study of the mechanisms and treatment of MS.     

Urodynamic findings in primary progressive multiple sclerosis are associated with increased volumes of plaques and atrophy in the central nervous system

OBJECTIVE: Voiding dysfunction is more frequent in primary progressive multiple sclerosis (PPMS) than in other subtypes of MS. We investigated whether lower urinary tract disorders are reflected in the extent of changes in brain and spinal cord detected by magnetic resonance imaging (MRI). METHODS: Micturition symptoms and specific urodynamic findings in 24 patients with PPMS were related to MRI abnormalities as analysed by segmentation and volumetric analysis. RESULTS: Urgency and urge incontinence were the most frequent urinary symptoms (83 and 75 %), while detrusor sphincter dyssynergia (DSD) (71%), detrusor hyperreflexia (58%) and obstruction (58%) were the most common micturition dysfunctions. Comparison between patients with detrusor hyperreflexia and those with normal bladder function revealed higher volumes of T2-weighted plaques in the brains of former (P = 0.01). In patients with hypotonic bladder the total brain volume was smaller (P = 0.02) and the number of thoracic plaques in T2-weighted images higher (P = 0.02) compared to patients with normal bladder function. Furthermore, DSD was associated with a higher volume of T2-weighted plaques in the brain (P = 0.02). CONCLUSIONS: Voiding dysfunction in PPMS is associated with increasing brain and spinal cord abnormalities. Urodynamic investigation is, however, needed for specific definition of micturition disturbances and should be made before therapeutic decisions.     

Combination of cuprizone and experimental autoimmune encephalomyelitis to study inflammatory brain lesion formation and progression

Brain‐intrinsic degenerative cascades are a proposed factor driving inflammatory lesion formation in multiple sclerosis (MS) patients. We recently described a model combining noninflammatory cytodegeneration (via cuprizone) with the classic active experimental autoimmune encephalomyelitis (Cup/EAE model), which exhibits inflammatory forebrain lesions. Here, we describe the histopathological characteristics and progression of these Cup/EAE lesions. We show that inflammatory lesions develop at various topographical sites in the forebrain, including white matter tracts and cortical and subcortical grey matter areas. The lesions are characterized by focal demyelination, discontinuation of the perivascular glia limitans, focal axonal damage, and neutrophil granulocyte extravasation. Transgenic mice with enhanced green fluorescent protein‐expressing microglia and red fluorescent protein‐expressing monocytes reveal that both myeloid cell populations contribute to forebrain inflammatory infiltrates. EAE‐triggered inflammatory cerebellar lesions were augmented in mice pre‐intoxicated with cuprizone. Gene expression studies suggest roles of the chemokines Cxcl10, Ccl2, and Ccl3 in inflammatory lesion formation. Finally, follow‐up experiments in Cup/EAE mice with chronic disease revealed that forebrain, but not spinal cord, lesions undergo spontaneous reorganization and repair. This study underpins the significance of brain‐intrinsic degenerative cascades for immune cell recruitment and, in consequence, MS lesion formation.     

Additive effect of the combination of glatiramer acetate and minocycline in a model of MS

There have been significant advances in the treatment of multiple sclerosis (MS) in recent years, but further improvement in therapy is required as not all patients have responded optimally. An approach to enhancing MS treatment is to combine drugs that impact on different aspects of the disease process. We have described that the tetracycline derivative, minocycline, attenuates the severity of experimental autoimmune encephalomyelitis (EAE), a model of MS. Here, we have evaluated the combination of minocycline and glatiramer acetate (GA), a current therapy in MS, on the course of EAE in mice. This combination resulted in a significant reduction of disease severity and disease burden with attenuation of the inflammation, axonal loss and demyelination.     

Activating transcription factor 6α deficiency exacerbates oligodendrocyte death and myelin damage in immune‐mediated demyelinating diseases

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) play a critical role in immune‐mediated demyelinating diseases, including multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), by regulating the viability of oligodendrocytes. Our previous studies show that activation of the PERK branch of the UPR protects myelinating oligodendrocytes against ER stress in young, developing mice that express IFN‐γ, a key pro‐inflammatory cytokine in MS and EAE, in the CNS. Several studies also demonstrate that PERK activation preserves oligodendrocyte viability and function, protecting mice against EAE. While evidence suggests activation of the ATF6α branch of the UPR in oligodendrocytes under normal and disease conditions, the effects of ATF6α activation on oligodendrocytes in immune‐mediated demyelinating diseases remain unknown. Herein, we showed that ATF6α deficiency had no effect on oligodendrocytes under normal conditions. Interestingly, we showed that ATF6α deficiency exacerbated ER stressed‐induced myelinating oligodendrocyte death and subsequent myelin loss in the developing CNS of IFN‐γ‐expressing mice. Moreover, we found that ATF6α deficiency increased EAE severity and aggravated EAE‐induced oligodendrocyte loss and demyelination, without affecting inflammation. Thus, these data suggest the protective effects of ATF6α activation on oligodendrocytes in immune‐mediated demyelinating diseases.