Pathogenic myelin-specific antibodies in multiple sclerosis target conformational proteolipid protein 1-anchored membrane domains

B cell clonal expansion and cerebrospinal fluid (CSF) oligoclonal IgG bands are established features of the immune response in multiple sclerosis (MS). Clone-specific recombinant monoclonal IgG1 Abs (rAbs) derived from MS patient CSF plasmablasts bound to conformational proteolipid protein 1 (PLP1) membrane complexes and, when injected into mouse brain with human complement, recapitulated histologic features of MS pathology: oligodendrocyte cell loss, complement deposition, and CD68+ phagocyte infiltration. Conformational PLP1 membrane epitopes were complex and governed by the local cholesterol and glycolipid microenvironment. Abs against conformational PLP1 membrane complexes targeted multiple surface epitopes, were enriched within the CSF compartment, and were detected in most MS patients, but not in inflammatory and noninflammatory neurologic controls. CSF PLP1 complex Abs provide a pathogenic autoantibody biomarker specific for MS.

A-194 Sustained Attention Differences Between Electrical Injury Patients and Combat Exposed Veterans with Post-Traumatic Stress Disorder

Objective: Electrical injury (EI) patients demonstrate heterogenous neuropsychological performance (NP), yet sustained attention (SA) has not been investigated. This study aimed to characterize differences in SA on the Conners’ Continuous Performance Test II (CPT-II) between patients with past EI and veterans with post-traumatic stress disorder (PTSD).

Method: Participants included EI patients and veterans with PTSD receiving neuropsychological evaluations at affiliated academic medical centers. Inclusion criteria for veterans involved meeting criteria for PTSD per the Clinician-Administered PTSD Scale for DSM-IV. EI and PTSD participants were included if they completed the CPT-II and failed < 1 performance validity tests. The 50 EI participants were 80% male, ages 19-64 (M=42, SD=10.67), and 94% White. The 35 PTSD participants were 94% male, ages 25-49 (M=33, SD=5.55), and 31% White, 45% Black, 20% Hispanic, and 3% biracial.

Results: Percentage of participants showing at least three atypical scores on the CPT-II was higher for EI (52%) compared with PTSD (20%) participants [χ^2 (1, N = 85) = 8.876, p < .003]. EI participants showed significantly greater SA difficulties on CPT-II overall standard error [F(1,84)=22.18, p< 0.001, ηp2=.21], variability of standard error [F(1,84)=7.70, p=0.028, ηp2=.09], reaction time by inter-stimulus interval (ISI) [F(1,84)=9.19, p=0.018, ηp2=.10], and standard error by ISI [F(1,84)=6.48, p=0.039, ηp2=.07]. All p-values were false discovery rate corrected.

Conclusions: EI participants demonstrated overall greater inconsistency in response speed with slower and inconsistent reaction times during different ISIs. EI patients display a unique pattern of SA performance compared to veterans with PTSD, which may relate to the variability in EI NP.

Onset of taste bud cell renewal starts at birth and coincides with a shift in SHH function

Embryonic taste bud primordia are specified as taste placodes on the tongue surface and differentiate into the first taste receptor cells (TRCs) at birth. Throughout adult life, TRCs are continually regenerated from epithelial progenitors. Sonic hedgehog (SHH) signaling regulates TRC development and renewal, repressing taste fate embryonically, but promoting TRC differentiation in adults. Here, using mouse models, we show TRC renewal initiates at birth and coincides with onset of SHHs pro-taste function. Using transcriptional profiling to explore molecular regulators of renewal, we identified Foxa1 and Foxa2 as potential SHH target genes in lingual progenitors at birth and show that SHH overexpression in vivo alters FoxA1 and FoxA2 expression relevant to taste buds. We further bioinformatically identify genes relevant to cell adhesion and cell locomotion likely regulated by FOXA1;FOXA2 and show that expression of these candidates is also altered by forced SHH expression. We present a new model where SHH promotes TRC differentiation by regulating changes in epithelial cell adhesion and migration.