Biology subjects

Walk, R.

Publications and source records attributed to Walk, R..

3 recordsLinked to original sources

bioRxiv2025

Ablation of VEGFA following a lumbar intervertebral disc injury attenuates intradiscal neurovascular features and prevents chronic low back pain symptoms

Despite its enormous burden on patients and society, chronic low back pain (LBP) has no effective therapeutic options. Innervation of the degenerating intervertebral disc (IVD) is suspected to cause discogenic LBP, but the mechanisms that orchestrate the IVDs neo-innervation and subsequent symptoms of LBP remain unknown. We hypothesize that Vascular Endothelial Growth Factor-A (VEGFA) critically mediates the neurite invasion in the IVD and contributes to chronic LBP. Initiating IVD degeneration through a mechanical injury, we evaluated the progression of neurovascular features into the IVD, as well as ensuring LBP symptoms and locomotive impairments at acute (3-weeks) and chronic (12-weeks) timepoints following the IVD injury. To determine the role of VEGFA, we utilized a mouse model with ubiquitously inducible recombination of the floxed Vegfa allele (UBC-CreERT2; Vegfafl/fl). The ablation of VEGFA after an IVD injury attenuated de novo neurite and vessel infiltration and impeded the expression of TRPA1, a nociceptive ion channel, in the dorsal root ganglion. The VEGFA-null animals, despite IVD degeneration, exhibited alleviated mechanical allodynia and improved locomotive performance. To determine the effects of IVD-derived VEGFA on endothelial cells and neurons, we co-cultured HMEC-1 endothelial cells and SH-SY5Y neurons with VEGFA-silenced human primary IVD cells. The endothelial cells co-cultured with VEGFA-silenced IVD cells exhibited reduced vessel growth and shifted their transcriptome and secretome from angiogenic to lymphangiogenic. The neurons co-cultured VEGFA-silenced IVD cells showed slowed growth and attenuated transcriptional programs for growth and elongation. These results show that VEGFA directs the growth of intradiscal vessels and neurites that cause low back pain and impaired function, and the inhibition of IVD-derived VEGFA during degeneration may be sufficient to prevent chronic pain behavior and motor impairment associated with discogenic low back pain. One Sentence SummaryVEGFA is a key mediator of neurovascular infiltration in the degenerating intervertebral disc and an essential driver of chronic low back pain, whose ablation prevents pain-related behaviors.

neuroscience↗

bioRxiv2025

The sex-specific effects of RAGE signaling and Type 2 Diabetes on mouse cortical bone mechanics, structure, and material properties

Individuals with type 2 diabetes (T2D) are prone to fracture at numerous skeletal sites despite presenting with a higher bone mineral density (BMD). The accumulation of Advanced Glycation End-products (AGEs) in the bone tissues of patients with T2D could be contributing to this paradox, of increased skeletal fragility with higher BMD. AGEs can impair bone cell homeostasis via the receptor for AGEs (RAGE). To investigate the effects of diabetes, AGE accumulation, and RAGE signaling on mouse cortical bone, we utilized male and female leptin receptor-deficient (db/db) mice from three age groups ranging from 3-14 months of age, which were crossed with animals carrying constitutively RAGE-deficient alleles (RAGE-/-). The morphological, mechanical and material outcomes were measured using microCT, 3-pt bending, and an AGE assay. We observed significant impairments dependent on age and sex to the bone matrix and whole-bone mechanical behavior due to diabetes with some impairments alleviated with the ablation of RAGE. In older female diabetic mice, the removal of RAGE signaling prevented the deficits in bone mechanics, morphology and tissue mineral density (TMD). Male diabetic mice without RAGE signaling exhibited improved material properties. The study demonstrated that some bone impairments associated with T2D are prevented with RAGE ablation and may be partially reversible with the inhibition of RAGE signaling. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=145 HEIGHT=200 SRC="FIGDIR/small/631018v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@75acedorg.highwire.dtl.DTLVardef@1ac01fforg.highwire.dtl.DTLVardef@1b70d34org.highwire.dtl.DTLVardef@c3f3a7_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

The progression of infiltrating neurovascular features and chemokine production of the caudal intervertebral disc following injury

Inflammatory cytokine production and de novo neurovascularization have been identified in painful, degenerated intervertebral discs (IVDs). However, the temporal trajectories of these key pathoanatomical features, including the cascade of inflammatory chemokines and neo-vessel and neurite infiltration, and their associations with IVD degeneration, remain relatively unknown. Investigating this process in the caudal mouse IVD enables the opportunity to study the tissue-specific response without confounding inflammatory signaling from neighboring structures. Thus this study aims to define the progression of chemokine production and neurovascular invasion during the IVD degeneration initiated by injury in the caudal spine 3-month-old C57BL6/J mice. Forty-nine IVD-secreted chemokines and matrix metalloproteinases (MMPs) was measured using multiplex ELISA, and the intradiscal infiltrating vessels (endomucin) and nerves (protein-gene-product 9.5) was quantified in the tissue volume using immunohistochemistry. Injury provoked the increase secretion of IL6, CCL2, CCL12, CCL17, CCL20, CCL21, CCL22, CXCL2 and MMP2 proteins. The centrality and structure of inflammatory networks in IVDs evolved over the 12 post-injury weeks, highlighting distinct responses between the acute and chronic phases. Neurites propagated rapidly within 2-weeks post-injury and remained relatively constant until 12-weeks. Vascular vessel length was observed to peak at 4-weeks post-injury and it regressed by 12-weeks. These findings identified the temporal flux of inflammatory chemokines and pain-associated pathoanatomy in a model of IVD degeneration using the mouse caudal spine.

bioengineering↗