Genetic ablation of bone marrow beta-adrenergic receptors in mice modulates miRNA-transcriptome networks of neuroinflammation in the paraventricular nucleus

Abstract

Elucidating molecular pathways regulating neuroimmune communication is critical for therapeutic interventions in conditions characterized by overactive immune responses and dysfunctional autonomic nervous system. We generated a bone marrow-specific adrenergic beta 1 and beta 2 knockout mouse chimera (AdrB1.B2 KO) to determine how sympathetic drive to the bone affects transcripts and miRNAs in the hypothalamic paraventricular nucleus (PVN). This model has previously exhibited a dampened systemic immune response and decreased blood pressure compared with control animals. Reduced sympathetic responsiveness of the bone marrow hematopoietic cells of AdrB1.B2 KO chimera led to suppression of transcriptional networks that included leukocyte cell adhesion and migration and T cell-activation and recruitment. Transcriptome responses related to IL-17a signaling and the renin-angiotensin system were also suppressed in the PVN. Based on the transcriptome response, we next computationally predicted miRNAs in the PVN that may underscore the reduced sympathetic responsiveness of the bone marrow cells. These included miR-27b-3p, miR-150, miR-223-3p, and miR-326. Using real-time PCR, we measured a downregulation in the expression of miR-150-5p, miR-205-5p, miR-223-3p, miR-375-5p, miR-499a-5p, miR-27b-3p, let-7a-5p, and miR-21a-5p in the PVN of AdrB1.B2 KO chimera, confirming computational predictions that these miRNAs are associated with reduced neuro-immune responses and the loss of sympathetic responsiveness in the bone marrow. Intriguingly, directional responses of the miRNA corresponded to mRNAs, suggesting complex temporal or circuit-dependent posttranscriptional control of gene expression in the PVN. This study identifies molecular pathways involved in neural-immune interactions that may act as targets of therapeutic intervention for a dysfunctional autonomic nervous system.

Keywords: bone marrow; network analysis; neuro-immune; sympathetic nervous system; transcriptomics.

Fig. 1.

A gene network for angiotensin (AGT), IL17, CD4, and NF-κB, which is suppressed in the b1/2-ARs knockout (KO) chimeras. Blue indicates that relative mRNA levels are decreased for the transcript. The square entities refer to cell processes; the oval entities refer to proteins in general; triangles represent ligands; and receptors are those molecules embedded in the membrane with the mushroom cap. DNA binding factors are those entities indicated with “feet.” The arrows indicate direction of entity regulation. Gene identifiers are provided in the abbreviation list (Supplemental Data 4, https://doi.org/10.6084/m9.figshare.11973198). There was n = 8 male mice/group.

Fig. 2.

An enriched pathway for microglial activation. Red indicates that relative mRNA levels are increased for the transcript, while blue indicates that relative mRNA levels are decreased for the transcript. Shapes and arrows are described in the legend to Fig. 1. Gene identifiers are provided in the abbreviation list (Supplemental Data 4). There was n = 8 male mice/group.

Fig. 3.

An enriched transcriptional pathway for cell processes related to neurons and glia. Red indicates that relative mRNA levels are increased for the transcript, while blue indicates that relative mRNA levels are decreased for the transcript. Shapes and arrows are described in the legend to Fig. 1. Gene identifiers are provided in the abbreviation list (Supplemental Data 4). There was n = 8 male mice/group.

Fig. 4.

MicroRNA expression in control and knockout mice. A: miR150-5p (P = 0.031), B: miR-223-3p (P = 0.0001), C: miR-18a-5p (P = 0.398), D: miR-205-5p (P = 0.0015), E: miR-375-5p, P = 0.016), F: miR-499a-5p (P = 0.0036), G: miR-7b-5p (P = 0.75), H: miR-27b-3p (P = 0.0028), I: miR-let-7a-5p (P = 0.0013), J: miR-21a-5p (P = 0003). Sample size was n = 8 per group, and significant differences (P < 0.05) in miRNA abundance between control and AdrB1.B2 KO mice are indicated by different letters.