Rodriguez, Moses

Abstract We present a novel immunotherapeutic strategy using a human B7-DC cross-linking Ab that prevents lung inflammation, airway obstruction, and hyperreactivity to allergen in a mouse model of allergic inflammatory airway disease. Dendritic cells (DC) have the ability to skew the immune response toward a Th1 or Th2 polarity. The sHIgM12 Ab functions in vitro by cross-linking the costimulatory family molecule B7-DC (PD-L2) on DC up-regulating IL-12 production, homing to lymph nodes, and T cell-activating potential of these APCs. Using chicken OVA as a model Ag, the administration of sHIgM12 Ab to BALB/c mice blocked lung inflammation, airway pathology, and responsiveness to methacholine, even after animals were presensitized and a Th2-polarized immune response was established. This therapeutic strategy was ineffective in STAT4-deficient animals, indicating that IL-12 production is critical in this system. Moreover, the polarity of the immune response upon in vitro restimulation with Ag is changed in wild-type mice, with a resulting decrease in Th2 cytokines IL-4 and IL-5 and an increase in the immunoregulatory cytokine IL-10. These studies demonstrate that the immune response of hypersensitized responders can be modulated using B7-DC cross-linking Abs, preventing allergic airway disease upon re-exposure to allergen.

Abstract The human MHC class II genes are associated with genetic susceptibility to multiple sclerosis (MS), a chronic inflammatory demyelinating disease of the CNS of presumed autoimmune origin. These genes encode for proteins responsible for shaping immune response. The exact role of HLA-DQ and -DR genes in disease pathogenesis is not well-understood due to the high polymorphism, linkage disequilibrium, and heterogeneity of human populations. The advent of HLA class II-transgenic (Tg) mice has helped in answering some of these questions. Previously, using single-Tg mice (expressing the HLA-DR or -DQ gene), we showed that proteolipid protein (PLP)91–110 peptide induced classical experimental autoimmune encephalomyelitis only in DR3.Aβ° mice, suggesting that DR3 (DRB1*0301) is a disease susceptible gene in the context of PLP. Human population studies have suggested that HLA-DQ6 (DQB1*0601) may be a protective gene in MS. To test this disease protection in an experimental model, we generated double-Tg mice expressing both HLA-DR3 and -DQ6. Introduction of DQ6 onto DR3-Tg mice led to a decrease in disease incidence on immunization with PLP91–110 peptide indicating a dominant protective role of DQ6. This protective effect is due to high levels of IFN-γ produced by DQ6-restricted T cells, which suppressed proliferation of encephalitogenic DR3-restricted T cells by inducing apoptosis. Our study indicates that DQ6 modifies the PLP91–110-specific T cell response in DR3 through anti-inflammatory effects of IFN-γ, which is protective for experimental autoimmune encephalomyelitis. Thus, our double-Tg mouse provides a novel model in which to study epistatic interactions between HLA class II molecules in MS.

Abstract Myeloid dendritic cells (mDC) activated with a B7-DC-specific cross-linking IgM Ab (B7-DC XAb) take up and retain Ag and interact with T cell compartments to affect a number of biologic changes that together cause strong antitumor responses and blockade of inflammatory airway disease in animal models. The molecular events mediating the initial responses in mDC remain unclear. In this study we show that B7-DC XAb caused rapid phosphorylation of the adaptor protein DAP12 and intracellular kinases Syk and phospholipase C-γ1. Pretreatment of mDC with the Syk inhibitor piceatannol blocked B7-DC XAb-induced Ag uptake with a concomitant loss of tumor protection in mice. Vaccination with tumor lysate-pulsed wild-type B7-DC XAb-activated mDC, but not TREM-2 knockout XAb-activated mDC, protected mice from lethal melanoma challenge. Multimolecular caps appeared within minutes of B7-DC XAb binding to either human or mouse mDC, and FRET analysis showed that class II, CD80, CD86, and TREM-2 are recruited in tight association on the cell surface. When TREM-2 expression was reduced in wild-type mDC using short hairpin RNA or by using mDC from TREM-2 knockout mice, in vitro DC failed to take up Ag after B7-DC XAb stimulation. These results directly link TREM-2 signaling with one change in the mDC phenotype that occurs in response to this unique Ab. The parallel signaling events observed in both human and mouse mDC support the hypothesis that B7-DC cross-linking may be useful as a therapeutic immune modulator in human patients.

Background: Approximately one-third of those with pediatric-onset multiple sclerosis (MS) experience cognitive impairment. Less is known concerning their change in cognitive functioning over time. Objective: Changes in cognitive function over time were measured in the largest pediatric cohort to date through the US Network of Pediatric MS Centers. Methods: A total of 67 individuals with pediatric MS ( n=62) or clinically isolated syndrome (CIS, n=5), ranging from 8–17 years of age (mean age±standard deviation (SD)=14.37±2.02) completed initial and follow-up neuropsychological testing after an average of 1.64±0.63 years apart. The nine tests administered measure general intellect, attention and working memory, verbal memory, visuomotor integration, language, and executive functioning. Results: Rate of impairment (having one-third or more scores in the impaired range) was 37% at baseline and 33% at follow-up. Tests commonly impaired were measures of visuomotor integration, speeded processing, and attention. Most tested did not decline over two years. There was no clear pattern of change on any specific measure. Conclusion: Findings suggest that, over short timeframes, stable or even improved performances on measures of cognitive ability can occur. Pediatric MS may instead prevent expected age-related cognitive gains.

Background: As remote infections with common herpes viruses are associated with modulation of the risk of multiple sclerosis (MS), we hypothesized that antibody concentrations against these viruses may further modify risk. As many common viruses are first encountered during childhood, pediatric MS offer a unique opportunity to investigate more closely their influence on susceptibility. Our aim was to determine if MS patients who were positive for these viruses had higher levels of antibodies to these viruses. We also assessed whether human leukocyte antigen (HLA)-DRB1*1501 genotype influenced viral antibody levels. Methods: Antibody response levels toward Epstein Barr virus (EBV), cytomegalovirus (CMV), and herpes simplex virus (HSV)-1, and HLA-DRB1*1501 status were determined in pediatric MS patients ( n=189) and controls ( n=38). Multivariate analyses were used, adjusted for age, gender, race, ethnicity and use of disease-modifying therapies. Results: The antibody concentrations against EBV (Epstein-Barr nuclear antigen 1 (EBNA-1), viral capsid antigen (VCA) and early antigen (EA)), CMV and HSV-1 were similar between pediatric MS patients and controls positive for seroconversion against the virus of interest. EBNA-1 humoral responses were higher in HLA-DRB1 positive individuals ( p=0.005) whereas other viral humoral responses were similar in HLA-DRB1 positive and negative individuals. Conclusion: Among those positive for EBNA-1, MS patients did not have higher levels of antibody response to EBNA-1: however, titers for EBNA-1 were higher in those who were HLA-DRB1 positive. This suggests that genotype might influence the humoral response to EBV. Whether other genotypes influence antibody response to other viruses remains to be determined.

In the largest sample studied to date, we measured cognitive functioning in children and adolescents with pediatric multiple sclerosis (n = 187) as well as those with clinically isolated syndrome (n = 44). Participants were consecutively enrolled from six United States Pediatric Multiple Sclerosis Centers of Excellence. Participants had a mean of 14.8 ± 2.6 years of age and an average disease duration of 1.9 ± 2.2 years. A total of 65 (35%) children with multiple sclerosis and 8 (18%) with clinically isolated syndrome met criteria for cognitive impairment. The most frequent areas involved were fine motor coordination (54%), visuomotor integration (50%), and speeded information processing (35%). A diagnosis of multiple sclerosis (odds ratio = 3.60, confidence interval = 1.07, 12.36, P = .04) and overall neurologic disability (odds ratio = 1.47, confidence interval = 1.10, 2.10, P = .03) were the only independent predictors of cognitive impairment. Cognitive impairment may occur early in these patients, and prompt recognition is critical for their care.

Background: It is unclear if all patients with relapsing–remitting multiple sclerosis (RRMS) ultimately develop progressive MS. Onset of progressive disease course seems to be age- rather than disease duration-dependent. Some forms of progressive MS (e.g. primary progressive MS (PPMS)) are uncommon in population-based studies. Ascertainment of patients with PPMS from clinic-based populations can facilitate a powerful comparison of age at progression onset between secondary progressive MS (SPMS) and PPMS but may introduce unclear biases. Objective: Our aim is to confirm that onset of progressive disease course is more relevant to the patient’s age than the presence or duration of a pre-progression relapsing disease course in MS. Methods: We studied a population-based MS cohort ( n =210, RRMS n =109, progressive MS n =101) and a clinic-based progressive MS cohort ( n =754). Progressive course was classified as primary (PPMS; n =322), single attack (SAPMS; n =112) and secondary progressive (SPMS; n =421). We studied demographics (chi 2 or t -test), age-of-progression-onset ( t -test) and time to Expanded Disability Status Scale of 6 (EDSS6) (Kaplan–Meier analyses). Results: Sex ratio ( p =0.58), age at progression onset ( p =0.37) and time to EDSS6 ( p =0.16) did not differ between the cohorts. Progression had developed before age 75 in 99% of patients with known progressive disease course; 38% with RRMS did not develop progression by age 75. Age at progression onset did not differ between SPMS (44.9±9.6), SAPMS (45.5±9.6) and PPMS (45.7±10.8). In either cohort, only 2% of patients had reached EDSS6 before onset of progression. Conclusions: Patients with RRMS do not inevitably develop a progressive disease course. Onset of progression is more dependent on age than the presence or duration of a pre-progression symptomatic disease course. Moderate disability is sustained predominantly after the onset of a progressive disease course in MS.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) with varied clinical presentations and heterogeneous histopathological features. The underlying immunological abnormalities in MS lead to various neurological and autoimmune manifestations. There is strong evidence that MS is, at least in part, an immune-mediated disease. There is less evidence that MS is a classical autoimmune disease, even though many authors state this in the description of the disease. We show the evidence that both supports and refutes the autoimmune hypothesis. In addition, we present an alternate hypothesis based on virus infection to explain the pathogenesis of MS.