# Defining the Molecular Basis of MicroRNA-146A Risk Allele Effects in Systemic Lupus Erythematosus > **NIH VA IK2** · VA EASTERN COLORADO HEALTH CARE SYSTEM · 2024 · — ## Abstract Systemic Lupus Erythematosus (SLE) is caused by a combination of genetic and environmental factors; however, the mechanisms by which these factors mediate disease risk remain incompletely defined. We recently elucidated a putative molecular mechanism for one of the few SLE risk loci that confers risk across all ancestral population groups examined. We fine-mapped the putative casual variant, rs2431697 and applied genome- editing approaches to demonstrate that this locus encodes an enhancer of MIR146A gene expression. Initial data suggested that this enhancer mediates SLE risk through its effects on type I interferon signaling, a pathway known to be dysregulated in SLE. However, follow up data reveal that despite in vitro effects on type I interferon production in myeloid cells, this risk variant does not impact serum type I Interferon activity in vivo in several large SLE cohorts. Interim observations suggest a plausible mechanism. First, rs2431697 is an expression quantitative trait locus eQTL for MIR146A in B cells. Second, the transcription factor, BHLHE40, exhibits allele- dependent physical interaction with the SLE risk variant in B cells. Third, our data highlight a role for both genes in B cell anergy, the usual mechanism of autoreactive B-cell tolerance to self-antigens. Together, these observations prompt our hypothesis. We hypothesize that the SLE risk enhancer at the MIR146A locus confers risk in SLE by modulating the development of B cell anergy. This hypothesis links the genetics of SLE with ongoing work by Dr. Harley during his rheumatology fellowship to develop novel tools to understand human B- cell anergy. Thus, we propose the following Aims. Aim 1) define the cellular locus of MIR146A dysregulation in vivo. To do this we will define whether the molecular correlates of our hypothesized model are present in diverse immune cell populations from healthy individuals and those with SLE analyzed immediately ex vivo or whether alternative models better explain how variation at this locus impacts SLE risk. We will apply a combination of RNA-Flow cytometry and spectral flow cytometric peripheral blood immunophenotyping with genetic analysis to determine whether the molecular correlates of our hypothesized model are present in B-cells ex vivo as predicted. Aim 2) [define the functional relationship between BHLHE40 and MIR146A in B cell anergy. We will determine whether MIR146A expression regulates autoreactive B-cell tolerance ex vivo in primary cells (Aim 2a), in vitro in cell lines (Aim 2b) and in vivo in mice (Aim 2c).] Aim 3) define whether global down regulation of microRNA metabolism occurs in anergic B cells. Experiments in T-cells indicate that most microRNAs undergo decay downstream of acute T-cell antigen receptor stimulus. Since chronic B-cell antigen receptor signaling is a major mechanism of autoreactive B-cell tolerance, global microRNA decay may enforce tolerance. To interpret our MIR146A results in this broader context, ... ## Key facts - **NIH application ID:** 10702105 - **Project number:** 1IK2BX005808-01A2 - **Recipient organization:** VA EASTERN COLORADO HEALTH CARE SYSTEM - **Principal Investigator:** Isaac T Harley - **Activity code:** IK2 (R01, R21, SBIR, etc.) - **Funding institute:** VA - **Fiscal year:** 2024 - **Award amount:** — - **Award type:** 1 - **Project period:** 2024-04-01 → 2029-03-31 ## Primary source NIH RePORTER: https://reporter.nih.gov/project-details/10702105 ## Citation > US National Institutes of Health, RePORTER application 10702105, Defining the Molecular Basis of MicroRNA-146A Risk Allele Effects in Systemic Lupus Erythematosus (1IK2BX005808-01A2). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10702105. Licensed CC0. --- *[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*