Paramagnetic rim lesions are associated with pathogenic CSF profiles and worse clinical outcomes in multiple sclerosis: a retrospective cross-sectional study

Background and Objective: Paramagnetic rims have been observed as a feature of some MS lesions on susceptibility-sensitive MRI and indicate ongoing inflammation, principally consisting of compartmentalized activated microglia/macrophages. We investigated clinical, MRI, and intrathecal (cerebrospinal fluid, CSF) associations of paramagnetic rim lesions (PRL) using 3T MRI in MS. Methods: This is a retrospective, cross-sectional analysis of patients at a single neuroimmunology clinic. All patients had standardized 3T MRI using a multiecho T2*-weighted sequence with susceptibility postprocessing (SWAN protocol, GE) as part of the inclusion criteria. SWAN-derived filtered phase maps and corresponding T2-FLAIR images were manually reviewed by one expert rater blinded to clinical data, and PRL were determined based on qualitative assessment of hypointense paramagnetic edges on corresponding T2-hyperintense lesions. Descriptive statistics, t-tests, ANOVA, and linear regression determined demographic, clinical, MRI, and intrathecal profile associations with the presence of one or more PRL. Results: One hundred and forty-seven (147) MS patients were included in this analysis (2 clinically isolated syndrome, 118 relapsing-remitting, 14 secondary progressive, 13 primary progressive). Baseline mean age was 48.8 years, disease duration 12.8 years, and median EDSS 2, with 79% women. Seventy-five percent of patients were receiving a disease-modifying therapy, and 79 patients (54%) had available cerebrospinal fluid (CSF) analysis. Sixty-three patients (43%) had at least 1 PRL. PRL status (presence or absence) did not vary by sex or EDSS but was associated with younger age (51 vs 46 years; p=0.01) and shorter disease duration (14.5 vs 10.5 years; p=0.01). PRL status was also associated with worse disease (MS severity score: 2.8 vs 3.7; p=0.05) and blood-brain barrier disruption as determined by higher protein and pathologically elevated albumin quotient, as well as the presence of CSF oligoclonal bands (all p≤0.05); there was no association with immunoglobulin index or synthesis rate. PRL status was additionally associated with higher burden of T2-hyperintense cerebral lesion volume (T2LV), higher age-adjusted cerebral brain volume loss (especially of gray matter), and poorer performance on multiple clinical measures, including the 9-hole peg test and symbol digit modalities test (but not timed 25-foot walk speed). Clinical and intrathecal profiles remained associated with PRL after adjustment for age and in many cases T2LV as well. Sensitivity analyses limited to subgroups of patients without disease activity at the time of CSF sampling remained supportive of results. Patients with PRL were being treated with higher-efficacy disease-modifying therapies at the time of the data query. Conclusions: PRL, an emerging noninvasive biomarker of chronic cerebral neuroinflammation in MS, are confirmed to be associated with greater disease severity and newly shown to be associated with intrathecal inflammation and blood-brain-barrier disruption.

MRSA-Induced Endothelial Permeability and Acute Lung Injury are Attenuated by FTY720 S-Phosphonate

Disruption of the lung endothelial barrier is a hallmark of acute respiratory distress syndrome (ARDS), for which no effective pharmacologic treatments exist. Prior work has demonstrated that FTY720 S-phosphonate (Tys), an analog of sphingosine-1-phosphate (S1P) and FTY720, exhibits potent endothelial cell (EC) barrier protective properties. In this study we investigated the in vitro and in vivo efficacy of Tys against methicillin-resistant Staphylococcus aureus (MRSA), a frequent bacterial cause of ARDS. Tys protected human lung EC from barrier disruption induced by heat-killed MRSA (HK-MRSA) or staphylococcal α-toxin and attenuated MRSA-induced cytoskeletal changes associated with barrier disruption, including actin stress fiber formation and loss of peripheral VE-cadherin and cortactin. Tys inhibited Rho and MLC activation after MRSA and blocked MRSA-induced NF-κB activation and release of the pro-inflammatory cytokines, IL-6 and IL-8. In vivo, intratracheal administration of live MRSA in mice caused significant vascular leakage and leukocyte infiltration into the alveolar space. Pre- or post-treatment with Tys attenuated MRSA-induced lung permeability and levels of alveolar neutrophils. Post-treatment with Tys significantly reduced levels of BAL VCAM-1 and plasma IL-6 and KC induced by MRSA. Dynamic intravital imaging of mouse lungs demonstrated Tys attenuation of HK-MRSA-induced interstitial edema and neutrophil infiltration into lung tissue. Tys did not directly inhibit MRSA growth or viability in vitro. In conclusion, Tys inhibits lung EC barrier disruption and pro-inflammatory signaling induced by MRSA in vitro and attenuates acute lung injury induced by MRSA in vivo. These results support the potential utility of Tys as a novel ARDS therapeutic strategy.

Essential Role of Rho-Associated Kinase in ABO Immune Complex-Mediated Endothelial Barrier Disruption

ABO immune complexes (ABO-IC) formed by ABO-incompatible antigen-antibody interaction are associated with hemolysis and platelet destruction in patients transfused with ABO-nonidentical blood products. However, the effects of ABO-IC on endothelial cells (EC) are unclear. ABO-IC were formed in vitro from normal donor-derived plasma and serum. Human pulmonary artery EC (HPAEC) were cultured and treated with media, ABO-identical and –non-identical plasma, and ABO-IC. EC barrier integrity was evaluated using transendothelial electrical resistance (TEER), scanning electron microscopy (SEM), vascular endothelial (VE)-cadherin and phalloidin staining, and Rho-associated Kinase (ROCK) inhibitor treatment. TEER revealed significant/irreversible barrier disruption within 1–2 h of exposure to ABO non-identical plasma and ABO-IC; this occurred independently of EC ABO type. Treatment with ABO-IC resulted in decreased VE-cadherin staining and increased phalloidin staining in a time-dependent manner, suggesting that the resultant increased EC barrier permeability is secondary to actin stress fiber formation and loss of cell surface VE-cadherin. Inhibition of ROCK was effective in protecting against IC-induced barrier disruption even two hours after ABO-IC exposure. ABO-IC causes increased EC barrier permeability by decreasing cell surface VE-cadherin and promoting stress fiber formation, which is preventable by inhibiting ROCK activation to protect against EC contraction and gap formation.