Download Investigation of the role of the Inflammasome triggering HIN200

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Investigation of the role of the Inflammasome triggering HIN200 gene
family in the Systemic Lupus Erythematosus murine model BXSB
Allyson Egan1, Jane Rose1,Jennifer Harper1, Michael Jones2 Department of Medicine1,
Genomics Laboratory, MRC Clinical Sciences Centre2 Hammersmith Hospital, Imperial
College London
Introduction
In murine models the telomeric region of chromosome 1 (C1q21-23) and a syntenic region in
humans has been associated with the development of Systemic Lupus Erythematosus (SLE)1.
Lupus prone model BXSB develops autoantibodies, nephritis and accelerated mortality similar
to human disease at six months. At 12 months the telomeric subcongenic B10.Yaa.Bxs3
develops a similar phenotype1. This interval encodes three candidate gene families – HIN200,
Slam and Fcgamma Receptor. The interferon response gene family HIN200 includes the gene
AIM2, a unique cytosolic DNA sensor which instigates the formation of the inflammasome
yielding cell death via IL-1β and IL-182. This project sought to develop a novel subcongenic
mouse model containing the HIN 200 locus, B10.Yaa.Bxs3.Ifi to investigate the potential role of
this gene family in SLE development.
Methods
(B10 x B10.Yaa.Bxs3)F1 male mice were backcrossed with B10 (non-autoimmune) females.
Three further crosses were performed to produce a novel subcongenic homozygote and secure
the lines. The recombinants were genotyped at six loci in the telomeric region of C1 using
polymerase chain reaction and sequenced for known single nucleotide polymorphisms within
the Slam locus. ANA slides were prepared using Hep2 cells and titres were quantified according
to the serial dilutions at which fluorescence in cells converted from positive to negative. Renal
H&E sections were graded according to mesangial hypercellularity and matrix increase. Grade
0= no histological change, G1<25%, G25-50%, G3 51-75% and G4>75%. Single cell
suspensions were prepared from splenocytes and flow cytometric analysis (FACs) of B and Tcells was performed.
Results
At six months, the subcongenic model B10.Yaa.Bxs3.Ifi’s titres of ANA, renal histology,
splenic length and weight were similar to the non-autoimmune B10.Yaa. At twelve months in
B10.Yaa.Bxs3.Ifi there was significant difference in the levels of ANA titres of antibodies,
evidence of nephritis and elevated splenic weights and lengths in comparison to the nonautoimmune strain B10.Yaa. These trends match the autoimmune parental strain B10.Yaa.Bxs.
FACS analysis of B10.Yaa, Bxs3.Ifi at six months demonstrated expanded B-cell CD45+
populations similar to autoimmune B10.Yaa. Bxs3, which was not demonstrated in the nonautoimmune B10.Yaa.
Conclusion
Microarray analysis has previously identified altered gene expression in the HIN200 gene
family in lupus prone strains BXSB and the New Zealand subcongenic Nba23. This project
which has created a novel HIN200 subcongenic, identifies that phenotypic features of SLE are
present in the subcongenic at 12 months, supporting the role of this interferon inducible gene
family as candidate genes for the development of SLE.
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References
1. Morley et al. JI 2004, 173:4277-4285 2. Burckstummer et al Nature Immunology vol 10, Number 3
March 2009 3. Haywood Morley et al Genes and Immunity (2006) 7, 250-263