Biomedical subjects

Jar-Chi Lee

Publications and source records attributed to Jar-Chi Lee.

11 recordsLinked to original sources

PubMed2006

Control of microglial neurotoxicity by the fractalkine receptor.

Microglia, the resident inflammatory cells of the CNS, are the only CNS cells that express the fractalkine receptor (CX3CR1). Using three different in vivo models, we show that CX3CR1 deficiency dysregulates microglial responses, resulting in neurotoxicity. Following peripheral lipopolysaccharide injections, Cx3cr1-/- mice showed cell-autonomous microglial neurotoxicity. In a toxic model of Parkinson disease and a transgenic model of amyotrophic lateral sclerosis, Cx3cr1-/- mice showed more extensive neuronal cell loss than Cx3cr1+ littermate controls. Augmenting CX3CR1 signaling may protect against microglial neurotoxicity, whereas CNS penetration by pharmaceutical CX3CR1 antagonists could increase neuronal vulnerability.

Analysis of Variance↗

PubMed2006

Immunological studies of mitoxantrone in primary progressive MS.

Mitoxantrone (MX) has demonstrated efficacy in multiple sclerosis (MS), but its immunologic mechanisms of action are poorly understood. Furthermore, no study has examined the immunological effects of MX in primary progressive MS (PPMS). This study investigated the immunological effects of MX therapy in PPMS patients. Lymphocyte phenotypes and chemokine receptor (CCR) expression were evaluated by flow cytometry on fresh PBMC from 20 PPMS patients enrolled in a placebo (PLC)-controlled trial of MX. Longitudinal data were collected at weeks 0, 12, 24, 36 and short-term data (pre-/post-infusion) were collected at weeks 0 and 36. CXCR3, CCR1, CCR2 and CCR5 on CD4 and CD8 T cells and CD14 monocytes were evaluated. MX therapy induced a significant increase in the proportion of CD8 T cells (CD45RO(-)) over 9 months. Expression of several CCR increased following MX treatment. Two of the eight MX-treated patients demonstrated dramatic upregulation (70-76%) of CCR2 on monocytes. These two patients were the only MX-treated patients to demonstrate active inflammation by magnetic resonance imaging (MRI). PLC patients did not show significant changes in CCR expression. MX therapy was not associated with selective loss of CD4, CD8 or CD14 cells 1 month after treatment or over 9 months. These results suggest that MX therapy leads to a longitudinal increase in CD8 T cells and may increase CCR in patients with inflammation on MRI. Overall, MX did not show extensive immune changes in PPMS, although patients with active disease (gadolinium enhancing lesions) may identify a subset of PPMS subjects who respond immunologically to MX therapy. An improved understanding of MX may help identify markers of disease activity and response to therapy.

Adult↗

PubMed2006

Significance of T2 lesions in multiple sclerosis: A 13-year longitudinal study.

OBJECTIVE: To evaluate the relation between T2 lesions and disease severity in relapsing-remitting multiple sclerosis (MS). METHODS: This article describes a 13-year longitudinal study in 30 patients. RESULTS: Patients were 36.3 +/- 6.0 years old, had MS for 6.1 +/- 5.8 years, Expanded Disability Status Scale was 2.2 +/- 0.8, and brain parenchymal fraction (BPF) was 0.825 +/- 0.015 at study entry. At last visit, Expanded Disability Status Scale was 4.4 +/- 1.95, Multiple Sclerosis Functional Composite was -0.34 +/- 1.7, and BPF was 0.774 +/- 0.037. Baseline T2 lesion volume correlated with the BPF of the last visit (r = -0.66; p < 0.0001), magnetization transfer ratio (MTR) in normal-appearing brain tissue (r = -0.52; p = 0.004), and lesion MTR (r = -0.76; p < 0.0001). Change in T2 lesion volume in the first 2 years correlated with BPF of the last visit (r = -0.40; p = 0.03), normal-appearing brain tissue MTR (r = -0.44; p = 0.015), lesion MTR (r = -0.46; p = 0.018), Multiple Sclerosis Functional Composite scores (r = -0.50; p = 0.005), and Paced Auditory Serial Addition Task scores (r = -0.52; p = 0.003). Age was a significant covariate for clinical but not magnetic resonance imaging outcomes. INTERPRETATION: T2 lesions in relapsing-remitting MS correlate strongly with brain tissue loss and brain tissue integrity 13 years later, and with clinical disease severity, though age significantly impacts the clinical correlation. The results provide direct evidence for the disability threshold hypothesis in MS and support monitoring T2 lesions in relapsing-remitting MS.

Adult↗

PubMed2006

Chemokine receptors as biomarkers in multiple sclerosis.

Leukocyte infiltrates characterize tissue inflammation and are thought to be integral in the pathogenesis of multiple sclerosis (MS). This attribute underlines the importance of understanding mechanisms of leukocyte migration. Chemokines are secreted proteins which govern leukocyte trafficking into targeted organs. Chemokine receptors (CKR) are differentially expressed on leukocytes and their modulation is a potential target for MS disease modifying therapies. Chemokines and their receptors are also potential biomarkers of both disease activity and response to treatment. We describe the fluctuations in CKR expression on peripheral leukocytes in a group of MS patients followed longitudinally for up to 36 months. We observed little fluctuation in CKR expression within each patient over time, despite considerable variability in CKR expression between patients. These observations suggest that individual patients have a CKR set point, and this set point varies from one patient to another. Evaluation of chemokines or chemokine receptors as biomarkers in MS will need to account for this individual variability in CKR expression.

Adult↗

PubMed2005

The NHLBI lymphangioleiomyomatosis registry: characteristics of 230 patients at enrollment.

RATIONALE: Pulmonary lymphangioleiomyomatosis is a progressive cystic lung disease that is associated with infiltration of atypical smooth muscle-like cells. Previous descriptions of clinical characteristics of subjects with lymphangioleiomyomatosis have been based on a limited number of patients. OBJECTIVES: To describe the clinical characteristics of subjects with pulmonary lymphangioleiomyomatosis, both sporadic and tuberous sclerosis-related forms. METHODS: Over a 3-yr period, from 1998 to 2001, 243 subjects with pulmonary lymphangioleiomyomatosis were enrolled into a national registry; 13 subjects who had already undergone lung transplantation were excluded for the purposes of this report. MEASUREMENTS AND MAIN RESULTS: All 230 subjects were women, aged 18 to 76 yr (mean +/- SE, 44.5 +/- 0.65 yr). The average age at onset of symptoms was 38.9 +/- 0.73 yr and at diagnosis was 41.0 +/- 0.65 yr. Tuberous sclerosis complex was present in 14.8% of subjects. Pulmonary manifestations, most commonly spontaneous pneumothorax, were the primary events leading to the diagnosis in 86.5% of cases. Nearly 55% of the subjects were being treated with a progesterone derivative. An obstructive pattern on pulmonary function testing was observed in 57.3% of the subjects, whereas 33.9% had normal spirometric results. Women with tuberous sclerosis-related lymphangioleiomyomatosis were younger and had less impaired lung function compared with those with the sporadic form. CONCLUSIONS: The age range of women afflicted with pulmonary lymphangioleiomyomatosis is broader than previously appreciated and the degree of pulmonary function can be quite variable, with one-third of subjects having normal spirometry at enrollment into this registry.

Adolescent↗

PubMed2005

Brain atrophy and magnetization transfer ratio following methylprednisolone in multiple sclerosis: short-term changes and long-term implications.

BACKGROUND: The short-term effect of corticosteroids on MRI measures of multiple sclerosis (MS) is not well understood and may have a significant impact when using these quantitative measures to evaluate disease activity and changes following other therapeutic interventions. OBJECTIVE: To determine the impact of a course of intravenous methylprednisolone (IVMP) on quantitative measures of disease activity and tissue injury in MS patients. METHODS: We prospectively measured brain parenchymal fraction (BPF), magnetization transfer ratio (MTR, lesional and whole brain), and lesion volumes on nine weekly brain MRI studies in ten MS patients receiving a course of IVMP. A group of nine MS patients not receiving IVMP served as controls. RESULTS: In comparison to untreated controls, BPF declined over the eight weeks following IVMP treatment (P <0.02). BPF decline was most prominent in patients with secondary progressive MS (SPMS, P <0.03), and was not seen in relapsing-remitting (RR) MS patients. Short-term change in BPF correlated with baseline BPF (r =0.62, P =0.05) and short-term change in lesional MTR (r = -0.55, P =0.03), but not with change in enhancing lesion volume. Short-term change in lesional MTR inversely correlated with baseline lesional and whole brain MTR (r = -0.79, P =0.04 for both). There was no significant difference between treated and control patients in measures of MTR or T2, T1 or enhancing lesion volumes. CONCLUSIONS: Patients with SPMS showed a greater decline in BPF following IVMP than RRMS patients. A correlation between changes in BPF and MTR suggest that these changes are secondary to altered water content within MS lesions. Differential response to a standardized therapeutic intervention in RRMS and SPMS suggests that responses to therapy may differ due to a fundamental pathologic difference between early and late stage MS.

Adult↗

PubMed2004

Association of fatigue and brain atrophy in multiple sclerosis.

Functional imaging studies have demonstrated a relationship between fatigue and altered cerebral activation patterns in multiple sclerosis patients, but no relationship between fatigue and brain atrophy has been demonstrated. We hypothesized that the subjective complaint of fatigue would predict the severity of destructive brain pathology. We assessed the relationship between fatigue and brain atrophy longitudinally in a cohort of 134 patients previously enrolled in a 2-year clinical trial of interferon beta-1a and re-evaluated 8 years after randomization into the trial. Brain atrophy was measured using the brain parenchymal fraction (BPF), and disability was measured using the Multiple Sclerosis Functional Composite at baseline, year 2 and year 8. Fatigue was measured using the Sickness Impact Profile's Sleep and Rest Scale (SIPSR) at baseline, year 2 and year 8. Linear regression analyses were used to assess the relationship between changes in fatigue and atrophy progression. Worsening fatigue on the SIPSR during the initial 2 years was significantly associated with progressive brain atrophy over the subsequent 6 years. The relationships between fatigue and brain atrophy were independent of changes in disability, mood, or other MRI characteristics. This suggests that the subjective complaint of fatigue is linked to destructive pathologic processes in RRMS patients.

Atrophy↗

PubMed2004

Defining interferon beta response status in multiple sclerosis patients.

IFN-beta is effective in reducing relapses and magnetic resonance imaging (MRI) lesions in multiple sclerosis (MS). It is assumed that individual therapeutic responses vary, but methods to identify IFN-beta responsiveness have not been validated. Our objective was to evaluate methods to classify IFN-beta responder status using relapses and MRI lesions. Data was analyzed from 172 patients who were followed up in a placebo-controlled clinical trial of IFN-beta1a for 2 years. Patients were classified as responders or nonresponders using (1) the number of relapses during the 2-year trial; (2) the number of new T2 lesions after 2 years; and (3) the number of gadolinium-enhancing lesions at year 1 and year 2 on study. Outcomes included 2-year change in the Expanded Disability Status Scale, Multiple Sclerosis Functional Composite, and brain parenchymal fraction. We found that subgroups with high on-study relapse numbers had more disease progression, differences between responder subgroups were similar in the IFN-beta1a and placebo arms. In contrast, subgroups with high numbers of new MRI lesions had significantly more disease progression only in the IFN-beta1a arm. Baseline characteristics failed to account for differential outcome. New MRI lesion activity during IFN-beta1a treatment correlates with poor response to IFN-beta1a. MRI classification may facilitate rational therapeutic decisions, better clinical trial designs, and studies correlating biomarkers with therapeutic response.

Adult↗

PubMed2003

Interferon gamma responses to myelin peptides in multiple sclerosis correlate with a new clinical measure of disease progression.

The relationship between autoreactivity to myelin antigens and disease progression in multiple sclerosis (MS) is not fully understood. We addressed this relationship by cross-sectionally comparing an objective measure of MS disability with immune cytokine responses to myelin proteins. The ELISPOT assay was used to determine the ex vivo interferon gamma (IFNgamma) and interleukin-10 (IL-10) production by peripheral blood mononuclear cells (PBMCs) in response to peptides spanning the entire proteolipid protein (PLP) and myelin basic protein (MBP) molecules in 20 patients with relapsing-remitting (RR) MS and 27 age- and sex-matched healthy controls. MS patients showed significantly higher MBP-induced IFNgamma responses and PLP-induced IL-10 responses compared with healthy controls. Using the Multiple Sclerosis Functional Composite (MSFC), a new multifactorial measure of disability, MS patients showed a significant correlation between the IFNgamma response to PLP peptides and MBP peptides, and disability. In contrast, in MS patients, there was no correlation between the MSFC and the response to unrelated control antigens or mitogens. These data show that myelin-specific T lymphocytes secreting the inflammatory cytokine IFNgamma correlate with functional impairment in MS, supporting an antigen-specific link between the immune response to myelin and disability in MS.

Adolescent↗

PubMed2003

Expression of CCR2, CCR5, and CXCR3 by CD4+ T cells is stable during a 2-year longitudinal study but varies widely between individuals.

Blockade of chemokine receptors (CKRs) has recently emerged as a possible pathway for therapeutic intervention in disease. In the present report, the expression of CCR2, CCR5, and CXCR3, associated with migration of mononuclear cells to inflamed tissue, was determined on CD4+ T cells in a 2-year longitudinal study of healthy volunteers using flow cytometry. Large interindividual variations in the expression of these receptors on CD4+ T cells were observed, whereas levels remained remarkably stable over time within subjects. The expression of CCR2, CCR5, and CXCR3 on CD4+ T cells was directly proportional to percentages of CD45RO(hi)/CD4+ T cells. In addition, highly significant associations between levels of CCR2, CCR5, and CXCR3 on CD4+ T cells were demonstrated in individual subjects, implying a common mechanism for regulating the expression of these CKRs on circulating T cells. These associations were not due to coexpression of CKRs on individual CD45RA-/CD4+ T cells. The results provide insight into the regulation of CKR expression on CD4+ T cells in vivo, and suggest that major fluctuations of CKR expression in individuals are uncommon.

Adult↗

PubMed2002

Sex differences in cytokine responses to myelin peptides in multiple sclerosis.

Many autoimmune diseases preferentially affect women; however, the underlying mechanisms for the sex differences are poorly understood. We examined sex-dependent differences in the immunologic response to myelin proteins in 22 multiple sclerosis (MS) patients and 22 healthy controls. Using ELISA spot assay (ELISPOT) methodology, interferon (IFN) gamma and IL-5 secretions were examined at the single cell level in response to overlapping proteolipid protein (PLP) peptides. As previously reported, we observed an overall disease effect in the IFNgamma response, such that MS patients were significantly higher than controls. With respect to PLP-induced IFNgamma secretion, both MS and control females responded higher than their corresponding males. Female MS patients demonstrated the highest responses compared to MS males or healthy controls of either sex. Although MS females had high IFNgamma responses to PLP, they had no IL-5 responses at all, suggesting strong Th1 skewing. In contrast, MS males had more IL-5 than control males, who lacked IL-5 responses. These IL-5 responses suggested that disease and gender are not independent, but rather interact to influence the cytokine response to myelin. The data suggest a gender bias towards Th1 responses in MS, which may contribute to the female predominance in this disease.

Adult↗