Emily Leibovitch

The formation of inflammatory demyelinated lesions in cerebral white matter.

Vascular permeability and inflammatory demyelination are intimately linked in the brain, but what is their temporal relationship? We aimed to determine the radiological correlates of the earliest tissue changes accompanying demyelination in a primate model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE) in the common marmoset.

Novel Marmoset (Callithrix jacchus) Model of Human Herpesvirus 6A and 6B Infections: Immunologic, Virologic and Radiologic Characterization

Human Herpesvirus 6 (HHV-6) is a ubiquitous virus with an estimated seroprevalence of 95% in the adult population. HHV-6 is associated with several neurologic disorders, including multiple sclerosis, an inflammatory demyelinating disease affecting the CNS. Animal models of HHV-6 infection would help clarify its role in human disease but have been slow to develop because rodents lack CD46, the receptor for cellular entry. Therefore, we investigated the effects of HHV-6 infections in a non-human primate, the common marmoset Callithrix jacchus. We inoculated a total of 12 marmosets with HHV-6A and HHV-6B intravenously and HHV-6A intranasally. Animals were monitored for 25 weeks post-inoculation clinically, immunologically and by MRI. Marmosets inoculated with HHV-6A intravenously exhibited neurologic symptoms and generated virus-specific antibody responses, while those inoculated intravenously with HHV-6B were asymptomatic and generated comparatively lower antibody responses. Viral DNA was detected at a low frequency in paraffin-embedded CNS tissue of a subset of marmosets inoculated with HHV-6A and HHV-6B intravenously. When different routes of HHV-6A inoculation were compared, intravenous inoculation resulted in virus-specific antibody responses and infrequent detection of viral DNA in the periphery, while intranasal inoculation resulted in negligible virus-specific antibody responses and frequent detection of viral DNA in the periphery. Moreover, marmosets inoculated with HHV-6A intravenously exhibited neurologic symptoms, while marmosets inoculated with HHV-6A intranasally were asymptomatic. We demonstrate that a marmoset model of HHV-6 infection can serve to further define the contribution of this ubiquitous virus to human neurologic disorders.

Perivenular brain lesions in a primate multiple sclerosis model at 7-tesla magnetic resonance imaging

Background Magnetic resonance imaging (MRI) can provide in vivo assessment of tissue damage, allowing evaluation of multiple sclerosis (MS) lesion evolution over time – a perspective not obtainable with postmortem histopathology. Relapsing–remitting experimental autoimmune encephalomyelitis (EAE) is an experimental model of MS that can be induced in the common marmoset, a small new world primate, and that causes perivenular white matter (WM) lesions similar to those observed in MS. Methods Brain lesion development and evolution were studied in vivo and postmortem in four marmosets with EAE through serial T2- and T2*-weighted scans at 7-tesla. Supratentorial WM lesions were identified and characterized. Results Of 97 lesions observed, 86 (88%) were clearly perivenular, and 62 (72%) developed around veins that were visible even prior to EAE induction. The perivenular configuration was confirmed by postmortem histopathology. Most affected veins, and their related perivascular Virchow-Robin spaces, passed into the subarachnoid space rather than the ventricles. Conclusion As in human MS, the intimate association between small veins and EAE lesions in the marmoset can be studied with serial in vivo MRI. This further strengthens the usefulness of this model for understanding the process of perivenular lesion development and accompanying tissue destruction in MS.

Custom fit 3D-printed brain holders for comparison of histology with MRI in marmosets

BACKGROUND MRI has the advantage of sampling large areas of tissue and locating areas of interest in 3D space in both living and ex vivo systems, whereas histology has the ability to examine thin slices of ex vivo tissue with high detail and specificity. Although both are valuable tools, it is currently difficult to make high-precision comparisons between MRI and histology due to large differences inherent to the techniques. A method combining the advantages would be an asset to understanding the pathological correlates of MRI. NEW METHOD 3D-printed brain holders were used to maintain marmoset brains in the same orientation during acquisition of ex vivo MRI and pathologic cutting of the tissue. RESULTS The results of maintaining this same orientation show that sub-millimeter, discrete neuropathological features in marmoset brain consistently share size, shape, and location between histology and ex vivo MRI, which facilitates comparison with serial imaging acquired in vivo. COMPARISON WITH EXISTING METHODS Existing methods use computational approaches sensitive to data input in order to warp histologic images to match large-scale features on MRI, but the new method requires no warping of images, due to a preregistration accomplished in the technique, and is insensitive to data formatting and artifacts in both MRI and histology. CONCLUSIONS The simple method of using 3D-printed brain holders to match brain orientation during pathologic sectioning and MRI acquisition enables rapid and precise comparison of small features seen on MRI to their underlying histology.

Droplet digital PCR for the precise quantification of HTLV-1

were interested to analyze the phenotype, function and dynamics of myeloid cell-subsets. Here we show, that depletion of CCR2 Ly6C inflammatory monocytes, a subset of recruited myeloid cells, results in decreased survival, suggesting their critical importance in host defense against T. gondii infection. Moreover, CCR2 Ly6C monocytes produce pro-inflammatory mediators, such as IL-1a, IL-1b, iNOS, TNF and ROS, confirming their anti-parasitic role. Furthermore, we demonstrate by adoptive transfer that inflammatory monocytes develop into two distinct subpopulations: CCR2 Ly6C F4/80 and CCR2 Ly6C F4/80. The CCR2 Ly6C F4/80 cells perform dendritic cell like functions such as interacting with T cells via MHC I and MHC II molecules. The CCR2 Ly6C F4/80 cell subset displays elevated phagocytic capacity and upregulates TREM2. Finally, we show that recruitment of Ly6C monocytes to the CNS is mediated by selectins. These results indicate the crucial role of recruited Ly6C monocytes upon cerebral toxoplasmosis, unraveling the dynamics and function of further differentiated mononuclear cell subsets in parasite control and immune regulation in the CNS.

Concentration dependent inhibitory effect of a nucleoside-based analog, 2,2-bis-hydroxymethyl-cyclopropavir, against human herpesvirus-6 replication

Objectives: To investigate the influence of onset age on the outcomes and prognosis of juvenile myasthenia gravis (JMG). Methods: A single-center retrospective and prospective study. One hundred and ninety-four patients with JMG, divided into two groups (Prepubertal and Postpubertal onset), were studied. Kaplan–Meier test was constructed to analyze the effect of onset age on the time of developing generalized MG (GMG) in JMG patients presenting with ocular MG (OMG) at onset. Risk factors of developing GMG were analyzed by using Logistic regression. Results: 1Of the 194 JMG patients evaluated, 186(96%) patients manifested extraocular muscle weakness as their initial symptoms, and among which 18 of 133 (14%) patients in Prepubertal JMG group and 12 of 53 (23%) patients in Postpubertal JMG group developed to GMG in the follow-up. The median progression course from OMG to GMG was 10 years in Prepubertal and 8 months in Postpubertal JMG groups (P = 0.000). 2The abnormal results of repetitive nerve stimulation (RNS) in extremity muscles was a risk predictor of developing GMG in patient with OMG at onset (OR, 10.103, 95% CI (3.017, 33.831), P= 0.000), while early corticosteroids was a protective issue (OR, 0.194, 95% CI (0.065, 0.577), P= 0.006).3Some Prepubertal JMG patients (44%) were treated with corticosteroids and 32% Postpubertal JMG patients chose early thymectomy which was performed in one year after onset. At last visit, about 50% patients who underwent early thymectomy, 43% patients treated with corticosteroids and 31% patients with late thymectomy achieved to ideal responses after more than one year follow-up. Conclusions:Abnormal RNSof extremitymuscles and early corticosteroids could be the prognostic factors of GMG conversion. Early corticosteroids for Prepubertal JMG and early thymectomy for Postpubertal JMG patients may be helpful for achieving ideal responses of MG.