Biology subjects

Hansen, V. L.

Publications and source records attributed to Hansen, V. L..

3 recordsLinked to original sources

bioRxiv2026

Loss of PRDM16 Drives Nasal Septal Deviation through Dysregulated TGFβ2 Signaling

Nasal septal deviation affects approximiately 20% of newborns globally and 80% individuals in the United States. GWAS have linked PRDM16, a histone methyltransferase, to craniofacial abnormalities, yet its role in nasal septum development remains poorly understood. Global Prdm16 knockout mice (Prdm16-/-) exhibit severe craniofacial defects resembling Pierre Robin Syndrome but are neonatally lethal, precluding their potential applications for postnatal study. To address this, we generated an osteochondral lineage-specific, Prdm16 conditional knockout (Col2a1-Cre; Prdm16flox/flox; cKO) mouse model. Both sexes of cKO mice display significantly shorter nasal bone length, with a sex-dependent increase in nasal bone volume fraction of 12 wk old males. Nasal septal deviation is detectable as early as postnatal day 15 and progresses with age. Single-cell RNA sequencing (scRNA-seq) of 4 wk old nasal septal cartilage revealed a marked shift in chondrocyte composition: Mgp+ chondrocytes were substantially reduced, while Col10a1+/Serpina3n+hypertrophic chondrocytes were dramatically increased, indicating PRDM16 regulates chondrocyte phenotypes. Spatial transcriptomics localized Mgp+ chondrocytes and Col1a1high/Col3a1+fibrotic cells to the septal cartilage-bone interface (the site of deviation in cKO mice). Intercellular communication analyses revealed a switch in dominant sender cells from the fibrotic population in WT to Mgp+chondrocytes in cKO. MultiNicheNet bioinformatic analyses identified elevated TGF{beta}2 signaling at the nasal septal deviation site. Specifically, TGF{beta}2 secreted by Mgp+ chondrocytes was predicted to promote Col1a1/Col1a2 expression, resulting in fibrotic extracellular matrix (ECM) deposition and osteogenesis; consistent with elevated RUNX2 in cKO mice. TGF{beta}2 immunohistochemical staining confirmed increased TGF{beta}2 cells in the fibrous ECM and apical nasal cartilage of cKO, but not WT mice. Loss of PRDM16 also increased chondrocyte apoptosis at 4 and 12 wks of age. These findings demonstrate that loss of PRDM16 drives hypertrophic and fibrotic remodeling of nasal septal cartilage through dysregulation of TGF{beta}2 signaling, establishing a mechanistic basis for nasal septal deviation.

developmental biology↗

bioRxiv2024

Integrative scRNA-seq and spatial transcriptomics uncovers distinct macrophage-fibroblast cross-talk in human hip synovium between patients with femoroacetabular impingement and osteoarthritis

Femoroacetabular impingement (FAI) and synovitis have been recognized as essential factors for developing osteoarthritis (OA) in the hip joints. However, little is known about altered synovial cellular compositions, their associated transcriptomic profiles, and cell-cell interactions between patients with FAI and hip OA. In the current study, by using integrative single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (Spatial-seq), we identified the molecular mechanisms by which synovial cells promote hip OA pathogenesis from FAI. Compared to FAI synovium, epiregulin (EREG)-enriched lining fibroblast-like synoviocytes (FLS) were significantly increased in the hip OA synovium. These EREG+ FLS are pro-inflammatory due to their high expression of CXCL1, IL8 (CXCL8), and MMPs. Furthermore, pseudotime analysis predicts that EREG+ FLS are potentially derived from DPP4+PI16+ sublining FLS. Importantly, analysis of cell-cell interactions indicates that fibroblast growth factor 2 (FGF2) secreted from COL1A1+IGFBP5+ fibrotic macrophages may signal through syndecan 4 (SDC4) expressed by EREG+ lining FLS, inducing the expression of IL6, IL8, MMP1, and PTGS2. The GO term analysis of activated genes downstream of FGF2-SDC4 signaling revealed that biological processes associated with inflammation and angiogenesis were upregulated in hip OA, while mechanical stimulus and skeletal muscle differentiation were dominant in FAI. Moreover, we also found that EREG+CCL20+MMP3hi lining FLS as well as most M{Phi} and monocyte populations are unique to hip OA patients when compared to knee OA and RA patients. The findings of this study offer a groundwork in tailoring novel targets and therapies for FAI and hip OA patients.

pathology↗

bioRxiv2022

Whole-Genome RNA Sequencing of Femoral Head Impingement Cartilage Identifies FGF18 As A Biomarker in Hip Osteoarthritis Progression

IntroductionThe natural history of Femoroacetabular Impingement (FAI) has been clinically associated with the development of hip osteoarthritis (OA); however, the pathobiological mechanisms underlying the transition from focal impingement to global joint degeneration remain unclear. The goal of the study was to investigate differences in transcriptomic profiles of the cartilage from FAI and hip OA patients using whole-genome RNA sequencing. MethodsThirty-seven patients were included in the study with 20 diagnosed with FAI undergoing arthroscopic treatment and 15 diagnosed with hip OA undergoing total hip arthroplasty (THA). Cartilage samples were obtained intraoperatively over the femoral head-neck junction for both FAI and OA cohorts. Whole-genome RNA sequencing was performed on 10 gender-matched patients in the FAI and OA cohorts with the remaining samples used for histopathologic analysis using the Osteoarthritis Research Society International (OARSI) grading system and qRT-PCR validation. Target validation was further confirmed with immunohistochemical staining for FGF18 on FAI and OA cartilage samples. ResultsWe identified a total of 3,531 Differentially Expressed Genes (DEGs) between the FAI and OA cohorts with multiple targets for genes implicated in canonical OA pathways. qRT-PCR validation confirmed increased expression of FGF18 and WNT16 in the FAI samples, while there was increased expression of MMP13 and ADAMTS4 in the OA samples. Expression levels of FGF18 and WNT16 were also higher in FAI samples with mild cartilage damage (OARSI grades 1-2) compared to FAI samples with severe cartilage damage or OA cartilage (OARSI grade 4-6). Immunohistochemical evaluation identified increased FGF18 staining in OARSI grade 1-2 FAI samples compared to OARSI grade 5-6 FAI and OA samples. ConclusionsRNA sequencing of cartilage of FAI and hip OA patients identified a negative association of FGF18 expression levels with cartilage damage severity, suggesting that FGF18 may be used as a marker for hip OA progression. Future evaluation of FGF18 signaling as well as other markers in early OA may yield further insight into disease prevention and treatment.

bioinformatics↗