Early Life Exposure to Lipopolysaccharide Suppresses Experimental Autoimmune Encephalomyelitis by Promoting Tolerogenic Dendritic Cells and Regulatory T Cells

Abstract

The rising incidence of autoimmune diseases such as multiple sclerosis (MS) in developed countries might be due to a more hygienic environment, particularly during early life. To investigate this concept, we developed a model of neonatal exposure to a common pathogen-associated molecular pattern, LPS, and determined its impact on experimental autoimmune encephalomyelitis (EAE). Mice exposed to LPS at 2 wk of age showed a delayed onset and diminished severity of myelin oligodendrocyte glycoprotein (MOG)-induced EAE, induced at 12 wk, compared with vehicle-exposed animals. Spinal cord transcript levels of CD3ε and F4/80 were lower in LPS- compared with PBS-exposed EAE animals with increased IL-10 levels in the LPS-exposed group. Splenic CD11c+ cells from LPS-exposed animals exhibited reduced MHC class II and CD83 expression but increased levels of CD80 and CD86 both before and during EAE. MOG-treated APC from LPS-exposed animals stimulated less T lymphocyte proliferation but increased expansion of CD4+FoxP3+ T cells compared with APC from PBS-exposed animals. Neuropathological studies disclosed reduced myelin and axonal loss in spinal cords from LPS-exposed compared with PBS-exposed animals with EAE, and this neuroprotective effect was associated with an increased number of CD3+FoxP3+ immunoreactive cells. Analyses of human brain tissue revealed that FoxP3 expression was detected in lymphocytes, albeit reduced in MS compared with non-MS patients’ brains. These findings support the concept of early-life microbial exposure influencing the generation of neuroprotective regulatory T cells and may provide insights into new immunotherapeutic strategies for MS.

Neuroinflammation and Endoplasmic Reticulum Stress Are Coregulated by Crocin To Prevent Demyelination and Neurodegeneration

“…Frontal brain white matter was collected at autopsy with consent from ageand sex-matched MS patients (total: n = 8; median age: 63 y; chronic progressive MS: n = 3; secondary progressive MS: n = 5) and non-MS (control) patients (total: n = 7; median age: 58 y; sepsis: n = 2; myocardial infarction: n = 2; HIV/AIDS: n = 1: cancer/leukemia n = 2) for RT-PCR analyses, as previously reported (32)(33)(34). Normal-appearing white matter (NAWM) was used from all clinical samples.…”

“…starting at day 7 post-EAE induction, whereas control EAE animals received daily i.p. PBS (32)(33)(34). Crocin prevents oligodendrocyte cytotoxicity induced by supernatants from astrocytes overexpressing Syncytin-1.…”

“…Ab (16-0031-86; eBioscience) at 10 mg/ml with or without 100 mM crocin (17304; Sigma) (34). For myelin oligodendrocyte glycoprotein (MOG)-specific proliferation assay, splenocytes were isolated from EAE-induced mice at peak of disease and were cultured in the presence of 20 mg/ml MOG peptide (prepared by the Peptide Synthesis Facility, University of Calgary) with or without 100 mM crocin.…”

“…Control animals were only injected with CFA and pertussis toxin. Animals were assessed daily for EAE severity for 25 d using a 0-14 rating scale (34). EAE mice received crocin (100 mg/kg/d; Sigma-Aldrich) daily and i.p.…”

“…Anti-CD3ε Ab was used with compbeads (552845; BD Biosciences) for single-color compensation controls. The total percentage (%) of the CD3ε + T lymphocyte proliferation population was analyzed using FlowJo (Tree Star software) (34).…”