Interacting quantitative trait loci control loss of peripheral tolerance and susceptibility to autoimmune ovarian dysgenesis after day 3 thymectomy in mice

H2 control of natural T regulatory cell frequency in the lymph node correlates with susceptibility to day 3 thymectomy-induced autoimmune disease

Day 3 thymectomy (D3Tx) results in a loss of peripheral tolerance mediated by natural regulatory T cells (nTregs) and development of autoimmune ovarian dysgenesis (AOD) and autoimmune dacryoadenitis (ADA) in A/J and (C57BL/6J × A/J) F(1) hybrids (B6A), but not in C57BL/6J (B6) mice. Previously, using quantitative trait locus (QTL) linkage analysis, we showed that D3Tx-AOD is controlled by five unlinked QTL (Aod1-Aod5) and H2. In this study, using D3Tx B6-Chr(A/J)/NaJ chromosome (Chr) substitution strains, we confirm that QTL on Chr16 (Aod1a/Aod1b), Chr3 (Aod2), Chr1 (Aod3), Chr2 (Aod4), Chr7 (Aod5), and Chr17 (H2) control D3Tx-AOD susceptibility. In addition, we also present data mapping QTL controlling D3Tx-ADA to Chr17 (Ada1/H2), Chr1 (Ada2), and Chr3 (Ada3). Importantly, B6-ChrX(A/J) mice were as resistant to D3Tx-AOD and D3Tx-ADA as B6 mice, thereby excluding Foxp3 as a susceptibility gene in these models. Moreover, we report quantitative differences in the frequency of nTregs in the lymph nodes (LNs), but not spleen or thymus, of AOD/ADA-resistant B6 and AOD/ADA-susceptible A/J, B6A, and B6-Chr17(A/J) mice. Similar results correlating with experimental allergic encephalomyelitis and orchitis susceptibility were seen with B10.S and SJL/J mice. Using H2-congenic mice, we show that the observed difference in frequency of LN nTregs is controlled by Ada1/H2. These data support the existence of an LN-specific, H2-controlled mechanism regulating the prevalence of nTregs in autoimmune disease susceptibility.

The postnatal maternal environment affects autoimmune disease susceptibility in A/J mice

The postnatal maternal environment is known to increase susceptibility to a number of autoimmune diseases. Here we asked whether the postnatal maternal environment could influence autoimmune disease development to day 3 thymectomy (d3tx)-induced autoimmune ovarian disease (AOD) and experimental allergic encephalomyelitis (EAE) in cross-fostered A/J and B6 mice. A/J pups foster-nursed by B6 mothers exhibit an increase in autoimmune disease development while cross-fostering B6 pups on A/J mothers did not alter their susceptibility. The increase in AOD incidence seen in foster-nursed d3tx A/J mice correlated with a decrease in the total number of CD4(+) T cells in the lymph nodes of these animals. Analysis of the cellular composition in the milk revealed that B6 mice shed significantly more maternally derived lymphocytes into their milk compared to A/J mothers. These data suggest that there are maternally derived postnatal factors that influence the development of autoimmune disease in A/J mice.

Genetic Control of Susceptibility to Autoimmune Gastritis

A familial component to the tendency to develop autoimmune gastritis has long been recognized. Although linkage to certain HLA alleles and an association with the endocrine autoimmune diseases thyroiditis and type 1 diabetes have been reported, little further progress has been achieved in clinical studies. In contrast, the mouse model of gastritis induced in the BALB/c strain by thymectomy in the third day of life has identified four linkage regions; two on distal chromosome 4 (Gasa1 and Gasa2), one on chromosome 6 (Gasa3) and one in the H2 (Gasa4). Three of these four genes colocalize with NOD mouse diabetes susceptibility genes--the strongest concordance identified to date between any two autoimmune diseases--reflecting the association between autoimmune diabetes and type 1 gastritis in humans.

SNPs upstream of the minimal promoter control IL-2 expression and are candidates for the autoimmune disease-susceptibility locus Aod2/Idd3/Eae3

IL-2, a T-cell growth and differentiation factor, plays an important role in immune homeostasis. Previously, we identified IL2 as a candidate for Aod2, a quantitative trait locus (QTL) controlling susceptibility to autoimmune ovarian dysgenesis (AOD) induced by day 3 neonatal thymectomy. Here, we report the identification of single-nucleotide polymorphisms (SNPs) in a region upstream of the minimal IL2 promoter (-2.8 kb to -300 bp), which distinguish AOD-susceptible A/J and AOD-resistant C57BL/6J (B6/J) mice. Six of the SNPs (-1010 C --> T, -962 C --> T, -926/-925 Delta Delta --> AC, -921 T --> C, -914 T --> C and -674 G --> A) contribute to the enhanced transcriptional activity of the extended B6/J promoter relative to A/J. Importantly, the -1010 SNP resides within a canonical AP-1-binding motif with the C --> T transition at this site abrogating AP-1 binding. Moreover, these SNPs segregate with differential production of IL-2 by CD4(+) T cells as well as susceptibility alleles at Idd3 and Eae3, QTL controlling insulin-dependent diabetes mellitus and experimental allergic encephalomyelitis. These are the first SNPs identified within the extended murine IL2 promoter that control differential IL-2 transcription in CD4(+) T cells, and, as such, they are not only candidates for Aod2, but are also candidates for a shared autoimmune disease-susceptibility locus underlying Idd3 and Eae3.

NALP inflammasomes: a central role in innate immunity

Inflammasomes are cytoplasmic multiprotein complexes that mediate the maturation of the proinflammatory cytokines interleukin-1beta (IL-1beta), IL-18, and possibly IL-33 by controlling the activation of the inflammatory caspases-1 and -5. Assembly of inflammasomes depends on NOD-like receptor (NLR) family members such as NALPs, NAIP, and IPAF. Various microbial and endogenous stimuli activate different types of inflammasomes. This article focuses on the Pyrin domain containing NLRs, known as NALP proteins. Recent findings provide exciting insights into how these proteins might be activated and also provide evidence of the critical role of the NALP inflammasomes in innate immunity and inflammatory diseases.

Inflammatory caspases and inflammasomes: master switches of inflammation

Fifteen years have passed since the cloning and characterization of the interleukin-1beta-converting enzyme (ICE/caspase-1), the first identified member of a family of proteases currently known as caspases. Caspase-1 is the prototypical member of a subclass of caspases involved in cytokine maturation termed inflammatory caspases that also include caspase-4 caspase -5, caspase -11 and caspase -12. Efforts to elucidate the molecular mechanisms involved in the activation of these proteases have uncovered an important role for the NLR family members, NALPs, NAIP and IPAF. These proteins promote the assembly of multiprotein complexes termed inflammasomes, which are required for activation of inflammatory caspases. This article will review some evolutionary aspects, biochemical evidences and genetic studies, underlining the role of inflammasomes and inflammatory caspases in innate immunity against pathogens, autoinflammatory syndromes and in the biology of reproduction.

Autoimmune ovarian disease in day 3-thymectomized mice: the neonatal time window, antigen specificity of disease suppression, and genetic control

Discovery of the CD4+CD25+ T cells has stemmed from investigation of the AOD in the d3tx mice. Besides CD4+CD25+ T cell depletion, d3tx disease induction requires effector T cell activation prompted by lymphopenia. This is supported by other neonatal AOD models in which T cell-mediated injury has been found to be triggered by immune complex or Ag immunization. In addition, there is growing evidence that support a state of neonatal propensity to autoimmunity, which depends on concomitant endogenous antigenic stimulation, concomitant nematode infection, resistance to CD4+CD25+ T cell regulation, and participation of the neonatal innate system. The suppression of d3tx disease by polyclonal CD4+CD25+ T cells appears to be dependent on endogenous Ag and the persistence of regulatory T cells. Thus, suppression of AOD occurs in the ovarian LN, and AOD emerges upon ablation of the input regulatory T cells; and in AIP, the hormone-induced expression of prostate Ag in the CD4+CD25+ T cell donors rapidly enhances the capacity to suppress disease over Ag negative donors. Finally, genetic analysis of AOD and its component phenotypes has uncovered seven Aod loci. As the general themes that emerged, significant epistatic interactions among the loci play a role in controlling disease susceptibility, the majority of the Aod loci are linked to susceptibility loci of other autoimmune diseases, and the genetic intervals encompass candidate genes that are differentially expressed between CD4+CD25+ T cells and other T cells. The candidate genes include Pdcd1, TNFR superfamily genes, H2, Il2, Tgfb, Nalp5 or Mater, an oocyte autoAg that reacts with autoantibody in sera of d3tx mice.

A T cell intrinsic role of Id3 in a mouse model for primary Sjogren's syndrome

Sjogren's syndrome is an autoimmune disease with clinical hallmarks of keratoconjunctivitis sicca (dry eyes) and xerostomia (dry mouth). The genetic basis of this autoimmune disease is poorly understood. Id3 is an immediate early-response gene in growth regulation and is involved in TCR-mediated T cell selection during T cell development. Here, we show that Id3-deficient mice develop many disease symptoms found in primary Sjogren's syndrome patients including dry eyes and mouth, lymphocyte infiltration in lachrymal and salivary glands, and development of anti-Ro and anti-La antibodies. Adoptive transfer experiment indicated a T cell intrinsic role for Id3 in the development of Sjogren's symptoms. Furthermore, genetic ablation of T cells or neonatal 3 day thymectomy in Id3-deficient mice showed a rescue of disease symptoms, suggesting a thymic origin of autoimmune T cells. Thus, this study establishes a critical connection between Id3-mediated T cell development and autoimmune diseases.

Aod1 controlling day 3 thymectomy-induced autoimmune ovarian dysgenesis in mice encompasses two linked quantitative trait loci with opposing allelic effects on disease susceptibility

Day 3 thymectomy (D3Tx) leads to a paucity of CD4(+)CD25(+) suppressor T cells, a loss of peripheral tolerance, and the development of organ-specific autoimmune disease in adult mice. Importantly, D3Tx does not lead to autoimmune disease in all mouse strains, indicating that this process is genetically controlled. Previously, we reported linkage of D3Tx-induced autoimmune ovarian dysgenesis (AOD) and its intermediate phenotypes, antiovarian autoantibody responsiveness, oophoritis, and atrophy, to five quantitative trait loci (QTL), designated Aod1 through Aod5. We also showed interaction between these QTL and H2 as well as Gasa2, a QTL controlling susceptibility to D3Tx-induced autoimmune gastritis. To physically map Aod1, interval-specific bidirectional recombinant congenic strains of mice were generated and studied for susceptibility to D3Tx-induced AOD. Congenic mapping studies revealed that Aod1 controls susceptibility to oophoritis and comprises two linked QTL with opposing allelic effects. Aod1a resides between D16Mit211 (23.3 cM) and D16Mit51 (66.75 cM) on chromosome 16. Aod1b maps proximal of Aod1a between D16Mit89 (20.9 cM) and D16Mit211 (23.3 cM) and includes the candidate genes stefin A1, A2, and A3 (Stfa1-Stfa3), inhibitors of cathepsin S, a cysteine protease required for autoantigen presentation, and the development of autoimmune disease of the salivary and lacrimal glands following D3Tx. cDNA sequencing revealed the existence of structural polymorphisms for both Stfa1 and Stfa2. Given the roles of cathepsins in Ag processing and presentation, Stfa1 and Stfa2 alleles have the potential to control susceptibility to autoimmune disease at the level of both CD4(+)CD25(+) suppressor and CD4(+)CD25(-) effector T cells.