Dataset Information

A20/TNFAIP3 heterozygosity predisposes to behavioral symptoms in a mouse model for neuropsychiatric lupus

ABSTRACT:

Background

Neuropsychiatric lupus (NPSLE) refers to the neurological and psychiatric manifestations that are commonly observed in patients with systemic lupus erythematosus (SLE). An important question regarding the pathogenesis of NPSLE is whether the symptoms are caused primarily by CNS-intrinsic mechanisms or develop as a consequence of systemic autoimmunity. Currently used spontaneous mouse models for SLE have already contributed significantly to unraveling how systemic immunity affects the CNS. However, they are less suited when interested in CNS primary mechanisms. In addition, none of these models are based on genes that are associated with SLE. In this study, we evaluate the influence of A20, a well-known susceptibility locus for SLE, on behavior and CNS-associated changes in inflammatory markers. Furthermore, given the importance of environmental triggers for disease onset and progression, the influence of an acute immunological challenge was evaluated.

Methods

Female and male A20 heterozygous mice (A20+/−) and wildtype littermates were tested in an extensive behavioral battery. This was done at the age of 10±2weeks and 24 ± 2 weeks to evaluate the impact of aging. To investigate the contribution of an acute immunological challenge, LPS was injected intracerebroventricularly at the age of 10±2weeks followed by behavioral analysis. Underlying molecular mechanisms were evaluated in gene expression assays on hippocampus and cortex. White blood cell count and blood-brain barrier permeability were analyzed to determine whether peripheral inflammation is a relevant factor.

Results

A20 heterozygosity predisposes to cognitive symptoms that were observed at the age of 10 ± 2 weeks and 24 ± 2 weeks. Young A20+/− males and females showed a subtle cognitive phenotype (10±2weeks) with distinct neuroinflammatory phenotypes. Aging was associated with clear neuroinflammation in female A20+/− mice only. The genetic predisposition in combination with an environmental stimulus exacerbates the behavioral impairments related to anxiety, cognitive dysfunction and sensorimotor gating. This was predominantly observed in females. Furthermore, signs of neuroinflammation were solely observed in female A20+/− mice. All above observations were made in the absence of peripheral inflammation and of changes in blood-brain barrier permeability, thus consistent with the CNS-primary hypothesis.

Conclusions

We show that A20 heterozygosity is a predisposing factor for NPSLE. Further mechanistic insight and possible therapeutic interventions can be studied in this mouse model that recapitulates several key hallmarks of the disease. Highlights • A novel mouse model for neuropsychiatric lupus was established.• Loss of 1 copy of A20/TNFAIP3 leads to neuroinflammation and cognitive symptoms.• Female-specific neuroinflammation was seen with age.• An environmental stimulus worsens the behavioral impairments.• The results show that the brain is the primary affected site.

SUBMITTER: Daems C

PROVIDER: S-EPMC8474646 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Systemic lupus erythematosus (SLE) is an autoimmune inflammatory rheumatic disease. SLE susceptibility is affected by multiple genetic elements, environmental factors, and their interactions. We aimed in this study to statistically and functionally characterize a gene-gene interaction (epistasis) recently documented to affect SLE risk. METHODS:Two single-nucleotide polymorphisms, rs2230926 in TNFAIP3 (A20) gene and rs131654 in UBE2L3 (UBCH7) gene, were genotyped in all 3525 Korean participants, and their SLE risk association and epistasis were statistically analyzed by calculating odds ratio (OR), 95% confidence interval (CI), and P values in genotype comparisons between 1318 SLE patients and 2207 healthy controls. Furthermore, their effects on gene functions were assessed by comparatively examining separate and combined effects of TNFAIP3 and UBE2L3 knockdowns on NF-?B transcription factor activity in human cells. RESULTS:SLE susceptibility is associated with TNFAIP3 rs2230926 (OR?=?1.9, 95% CI 1.6-2.4, P =?8.6?×?10-11) and UBE2L3 rs131654 (OR?=?1.2, 95% CI 1.1-1.4, P =?1.1?×?10-4) in a Korean population of this study. Their risk-associated alleles synergistically elevate SLE susceptibility in both multivariate logistic regression analysis (ORinteraction =?1.6, P =?0.0028) and genotype-stratified analysis (ORinteraction =?2.4), confirming the synergistic TNFAIP3-UBE2L3 interaction in SLE risk. Additionally, the SLE-susceptible alleles confer decreased TNFAIP3 expression (P =?1.1?×?10-6, n =?610) and increased UBE2L3 expression (P =?9.5?×?10-11, n =?475), respectively, in B cell analysis of the International HapMap Project individuals with adjustment for ethnicity. Furthermore, when compared with TNFAIP3 non-knockdown and UBE2L3 knockdown in human HeLa cells, TNFAIP3 knockdown and UBE2L3 non-knockdown synergistically increase three cytokines, CCL2, CXCL8 (IL8), and IL6, all regulated by NF-?B in the human TNFR signaling pathway. CONCLUSIONS:A synergistic interaction between TNFAIP3 and UBE2L3 genes is observed in SLE risk, as being evident in comparison of genotype distributions between SLE patients and controls. Additionally, the synergistic gene-gene interaction is functionally validated, as TNFAIP3 reduction and UBE2L3 augment exert synergism in activation of NF-?B and subsequent induction of inflammatory cytokines. Accordingly, SLE inflammation and risk could be synergistically alleviated by TNFAIP3 upregulation and UBE2L3 downregulation.