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Identification of gene regions regulating inflammatory microglial response in the rat CNS after nerve injury
Margarita Diez1, Nada Abdelmagid, Karin Harnesk
1Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, S171 76 Stockholm, Sweden. Margarita.Diez@ki.se
Abstract:
Local CNS inflammation takes place in many neurological disorders and is important for autoimmune neuroinflammation. Microglial activation is strain-dependent in rats and differential MHC class II expression is influenced by variations in the Mhc2ta gene. Despite sharing Mhc2ta and MHC class II alleles, BN and LEW.1N rats differ in MHC class II expression after ventral root avulsion (VRA). We studied MHC class II expression and glial activation markers in BN rats after VRA. Our results demonstrate that MHC class II expression originates from a subpopulation of IBA1(+), ED1(-), and ED2(-) microglia. We subsequently performed a genome-wide linkage scan in an F2(BNxLEW.1N) population, to investigate gene regions regulating this inflammatory response. Alongside MHC class II, we studied the expression of MHC class I, co-stimulatory molecules, complement components, microglial markers and Il1b. MHC class II and other transcripts were commonly regulated by gene regions on chromosomes 1 and 7. Furthermore, a common region on chromosome 10 regulated expression of complement and co-stimulatory molecules, while a region on chromosome 11 regulated MHC class I. We also detected epistatic interactions in the regulation of the inflammatory process. These results reveal the complex regulation of CNS inflammation by several gene regions, which may have relevance for disease.
Insights
Central nervous system (CNS) inflammation involves complex genetic regulation. This study identifies specific gene regions on chromosomes 1, 7, 10, and 11 that control inflammatory responses in the CNS.
Area of Science:
- Neuroimmunology
- Genetics of neuroinflammation
Background:
- Local central nervous system (CNS) inflammation is crucial in neurological disorders and autoimmune neuroinflammation.
- Microglial activation and major histocompatibility complex (MHC) class II expression are influenced by genetic factors and vary between rat strains.
- Distinct MHC class II expression patterns exist between BN and LEW.1N rat strains post-ventral root avulsion (VRA), despite shared genetic components.
Purpose of the Study:
- To investigate the genetic regulation of CNS inflammation and glial activation markers following ventral root avulsion (VRA) in BN rats.
- To identify specific gene regions controlling the expression of MHC class II and other inflammatory markers.
- To explore the genetic basis for differential inflammatory responses observed between rat strains.
Main Methods:
- Ventral root avulsion (VRA) model in BN rats to study MHC class II expression and glial activation.
- Genome-wide linkage scan in an F2(BNxLEW.1N) intercross population.
- Analysis of gene expression for MHC class I, MHC class II, co-stimulatory molecules, complement components, microglial markers, and Interleukin-1 beta (Il1b).
Main Results:
- MHC class II expression was found to originate from a specific subpopulation of microglia (IBA1(+), ED1(-), ED2(-)).
- Gene regions on chromosomes 1 and 7 commonly regulate MHC class II and other inflammatory transcripts.
- Chromosome 10 regulates complement and co-stimulatory molecules, while chromosome 11 regulates MHC class I expression.
- Epistatic interactions were identified in the regulation of the CNS inflammatory process.
Conclusions:
- CNS inflammation is intricately regulated by multiple genetic regions, including those on chromosomes 1, 7, 10, and 11.
- These findings highlight the complex genetic architecture underlying neuroinflammatory responses.
- Understanding these genetic factors may offer insights into the pathogenesis and potential therapeutic targets for neurological diseases.
