Impaired wound healing, fibrosis, and cancer: The paradigm of recessive dystrophic epidermolysis bullosa

Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a devastating skin blistering disease caused by mutations in the gene encoding type VII collagen (C7), leading to epidermal fragility, trauma-induced blistering, and long term, hard-to-heal wounds. Fibrosis develops rapidly in RDEB skin and contributes to both chronic wounds, which emerge after cycles of repetitive wound and scar formation, and squamous cell carcinoma—the single biggest cause of death in this patient group. The molecular pathways disrupted in a broad spectrum of fibrotic disease are also disrupted in RDEB, and squamous cell carcinomas arising in RDEB are thus far molecularly indistinct from other sub-types of aggressive squamous cell carcinoma (SCC). Collectively these data demonstrate RDEB is a model for understanding the molecular basis of both fibrosis and rapidly developing aggressive cancer. A number of studies have shown that RDEB pathogenesis is driven by a radical change in extracellular matrix (ECM) composition and increased transforming growth factor-beta (TGFβ) signaling that is a direct result of C7 loss-of-function in dermal fibroblasts. However, the exact mechanism of how C7 loss results in extensive fibrosis is unclear, particularly how TGFβ signaling is activated and then sustained through complex networks of cell-cell interaction not limited to the traditional fibrotic protagonist, the dermal fibroblast. Continued study of this rare disease will likely yield paradigms relevant to more common pathologies

NPC1 deficiency impairs cerebellar postnatal development of microglia and climbing fiber refinement in a mouse model of Niemann-Pick disease type C.

Little is known about the effects of NPC1 deficiency in brain development and whether these effects contribute to neurodegeneration in Niemann-Pick disease type C (NPC). Degeneration of cerebellar Purkinje cells occurs at an earlier stage and to a greater extent in NPC; therefore, we analyzed the effect of NPC1 deficiency on microglia and on climbing fiber synaptic refinement during cerebellar postnatal development using th

Increased interactions and engulfment of dendrites by microglia precede Purkinje cell degeneration in a mouse model of Niemann Pick Type-C.

Niemann Pick Type-C disease (NPC) is an inherited lysosomal storage disease (LSD) caused by pathogenic variants in the Npc1 or Npc2 genes that lead to the accumulation of cholesterol and lipids in lysosomes. NPC1 deficiency causes neurodegeneration, dementia and early death. Cerebellar Purkinje cells (PCs) are particularly hypersensitive to NPC1 deficiency and degenerate earlier than other neurons in the brain. Activation of microglia is an important contributor to PCs degeneration in NPC. However, the mechanisms by which activated microglia promote PCs degeneration in NPC are not completely understood. Here, we are demonstrating that in the Npc1nmf164 mouse cerebellum, microglia in the molecular layer (ML) are activated and contacting dendrites at early stages of NPC, when no loss of PCs is detected. During the progression of PCs degeneration in Npc1nmf164 mice, accumulation of phagosomes and autofluorescent material in microglia at the ML coincided with the degeneration of dendrites and PCs. Feeding Npc1nmf164 mice a western diet (WD) increased microglia activation and corresponded with a more extensive degeneration of dendrites but not PC somata. Together our data suggest that microglia contribute to the degeneration of PCs by interacting, engulfing and phagocytosing their dendrites while the cell somata are still present

Abstract Number ‐ 168: Conventional angiography versus non‐invasive imaging in the assessment of symptomatic carotid disease

Introduction The indication for carotid endarterectomy in symptomatic carotid stenosis of 50% or more was established based on catheter angiography. Yet, in practice, operative referral is still largely based on non‐invasive imaging. We sought to determine the discrepancy between the two modalities in our retrospective cohort. Methods We retrospectively collected data from consecutive symptomatic patients between 2019 and 2021 at our institution who were referred for evaluation and possible stenting of carotid disease based on non‐invasive imaging showing moderate to severe stenosis or occlusion. All patients underwent digitally subtracted angiography (DSA) and were treated with stenting if there was stenosis of 50% or above or if there was presence of a string sign. Otherwise, they were continued on best medical therapy. Results 98 total patients were referred for evaluation of carotid disease (Median age 60, 37% women). 21/98 were found to have a carotid occlusion on non‐invasive imaging, of those, 6 (28%) were found to have a string sign on CTA and were treated with stenting. 77/98 were found to have moderate to severe carotid artery stenosis based on non‐invasive imaging. Of those, 31 patients (40%), were not found to have significant carotid artery stenosis and were not treated with stenting. Out of total 99 patients who were referred for carotid intervention based on non‐invasive imaging, 38 (40%) patients had a change in the treatment plan. Conclusions 40% of the patients who were referred for revascularization based on non‐invasive imaging had a change in the treatment after conventional catheter angiography. Larger studies are warranted to confirm our findings

Impaired Wound Healing, Fibrosis, and Cancer: The Paradigm of Recessive Dystrophic Epidermolysis Bullosa

Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a devastating skin blistering disease caused by mutations in the gene encoding type VII collagen (C7), leading to epidermal fragility, trauma-induced blistering, and long term, hard-to-heal wounds. Fibrosis develops rapidly in RDEB skin and contributes to both chronic wounds, which emerge after cycles of repetitive wound and scar formation, and squamous cell carcinoma—the single biggest cause of death in this patient group. The molecular pathways disrupted in a broad spectrum of fibrotic disease are also disrupted in RDEB, and squamous cell carcinomas arising in RDEB are thus far molecularly indistinct from other sub-types of aggressive squamous cell carcinoma (SCC). Collectively these data demonstrate RDEB is a model for understanding the molecular basis of both fibrosis and rapidly developing aggressive cancer. A number of studies have shown that RDEB pathogenesis is driven by a radical change in extracellular matrix (ECM) composition and increased transforming growth factor-beta (TGFβ) signaling that is a direct result of C7 loss-of-function in dermal fibroblasts. However, the exact mechanism of how C7 loss results in extensive fibrosis is unclear, particularly how TGFβ signaling is activated and then sustained through complex networks of cell-cell interaction not limited to the traditional fibrotic protagonist, the dermal fibroblast. Continued study of this rare disease will likely yield paradigms relevant to more common pathologies

The role of c‐Kit/sGC signaling axis in vascular reactivity and hypertension

A. Introduction The receptor tyrosine kinase c‐Kit has been recently found to have a role in vasculoprotection. Genetic deletion of c‐Kit in smooth muscle cells increases aortic plaque accumulation and atherosclerosis burden in conditional hyperlipidemic mice. The present study tests whether a c‐Kit deficiency in mutant mice (KitW/Wv) leads to hypertension and impaired vascular relaxation. B. Methods Female and male c‐Kit mutant (KitW/Wv) and littermate (Kit+/+) control mice were commercially available (Jackson lab). Blood pressure was determined in conscious mice using the tail‐cuff method. The first‐order branch of mesenteric artery was mounted into a pressure myograph (DMT, Aarhus, Denmark) to assess endothelium‐dependent and ‐independent vasoreactivity under isobaric conditions. A search for differentially expressed genes between c‐Kit mutant and control SMC was performed using the Mouse MI‐Ready microarray (Ocean Ridge Biosciences). C. Results The deficiency of c‐Kit causes hypertension in mutant mice with respect to their control littermates (mean arterial pressure: 137.5 ± 5.0 vs. 113.06 ± 0.0, p=0.007). Acetylcholine (ACh) induced a concentration‐dependent relaxation of norepinephrine pre‐contracted vessels in both mutant and littermate mice. The Cox inhibitor indomethacin compromised ACh‐induced vasorelaxation only in c‐Kit deficient vessels but not in those from control mice, which highlighted the importance of endothelium‐derived prostaglandins for vasorelaxation in the absence of c‐Kit. Conversely, arteries of mutant mice were poor responders to a NO agonist (SNP). The secondary messenger, cyclic guanosine monophosphate, vasodilated both types of vessels in a similar manner, which indicated that defective NO activity in mutants was due to deficiencies in soluble guanylyl cyclase (sGC) or NO synthesis. A significant downregulation of smooth muscle sGC beta 1 subunit was further found in c‐Kit mutant cells using transcriptomics analysis. D. Conclusion These results suggest the existence of a novel c‐Kit/sGC signaling axis in SMC that may be relevant for the control of vascular reactivity and hypertension. This is from the Experimental Biology 2018 Meeting. There is no full text article associated with this published in The FASEB Journal

Abstract 15554: Smooth Muscle Cells Specific Gene Inactivation of Lysyl Oxidase Reduces Atherosclerosis Burden and Plaque Calcification in Hyperlipidemic Mice

Byline: Filipe F Stoyell Conti, Univ of Miami, Pembroke Pnes, FL; Miguel Rojas, Surgery, Univ of Miami; Zachary Zigmond, Surgery, Univ of Miami; Mohdahmar Rauf, Univ of Miami, FL; Laisel Martinez, UNIVERSITY OF MIAMI, Miami, FL; Roberto I Vazquez-Padron, UNIVERSITY OF MIAMI, Miami, FL Aim: Dissect the mechanisms by which LOX increases atherogenesis and plaque calcification in hyperlipidemic mice. Methods: LOX conditional knockout [LOXf/fMyh11-CreERT2 ApoE -/-] and control littermate [LOXwt/wtMyh11-CreERT2 ApoE -/-] mice were injected with tamoxifen before high fat diet (HFD) feeding for atherosclerosis and calcification assessment and molecular analyses. Results: scRNA sequence showed full Lox gene inactivation in 72.5% of the aortic SMCs without any significant Loxl compensatory regulation. Gene deletion in SMCs decreased global arterial LOX deposition by ~3-fold in relation to control mice. Surprisingly, the loss of vascular LOX neither promoted aneurysm nor affected the aorta's stiffness. However, it reduced atherosclerosis burden (WT: 23Ø1 vs. KO: 13Ø2 %, p ëñ0.01) and calcium deposition (11.8Ø3 versus 5Ø0.4%, pëñ 0.05) within the plaque after 16 weeks of high fat diet (HFD). Using bulk RNA sequencing, we further demonstrated that Lox gene inactivation leads to a marked decrease in Frizzled Related Protein-3 (FRZB) gene expression (127-fold and pëñ0.0001), a biphasic modulator of the proatherogenic Wnt signaling that facilitates the association of ð-catenin with TCF4 in the nucleus. The compromised FRZB /ð-catenin/TCF4 signaling axis reduced the downstream production of Bone Morphogenetic Protein 2 (BMP2), which is responsible for the osteogenic transition of SMCs. Further scRNAseq analysis of atherosclerotic aortas from conditional KO and control mice also showed a reduction of BMP2 in SMCs. Interestingly, genetic inactivation of LOX increased the number of contractile SMCs (KO: 40 vs. WT: 7 %), characterized by the high expression of ACTA2 and TAGLN, in the aorta of HFD fed mice when compared to the control group. BAPN, an irreversible inhibitor of LOX activity, was not able to reduce BMP2 expression and protein levels nor reduce calcium deposition in vitro, suggesting that the pro-calcification effect of LOX is not activity dependent. Conclusions: Vascular gene inactivation of Lox protects mice against atherosclerosis by reducing ð-catenin/TCF4/BMP2 proatherogenic signaling.Professiona

Abstract 199: Conditional Inactivation Of Lysyl Oxidase In Smooth Muscle Cells Reduces Atherosclerosis Burden And Plaque Calcification In Hyperlipidemic Mice Through Suppression Of The β-catenin/tcf4 Signaling Axis

Introduction: In atherosclerosis development and complications, the importance of lysyl oxidase (LOX), a copper-dependent amino-oxidase that crosslinks collagen and elastin and controls gene expression, is not well established. Hypothesis: Inactivation of LOX in smooth muscle cells (SMC) decreases atherosclerosis burden and plaque calcification in hyperlipidemic mice. Methods: qRT-PCR, Western blot, and scRNAseq demonstrated the loss of Lox gene expression in SMC of ApoE conditional mice (Lox f/f Myh11-CreERT2 ApoE-/-) but not in littermate control animals after tamoxifen injections. Surprisingly, vascular loss of LOX did not increase the risk of aneurysms nor affected the aorta's stiffness. However, it reduced atherosclerosis burden with respect to control mice (13±2 versus 23±1%, p < 0.01) after 16 weeks of high fat diet (HFD). There was also a significant reduction in calcium deposition (5±0.4 versus11.8±3, p < 0.05) within the plaque of LOX knockout mice versus control. Aortic whole genome transcriptomic analysis revealed a positive correlation between Lox gene expression and Frizzled-related protein 3 ( Frzb ), a biphasic modulator of Wnt signaling that facilitates the association of β-catenin with TCF4 in the nucleus. scRNAseq analysis confirmed the downregulation of Bmp2 and Myc , both β-catenin/TCF4 regulated genes, in SMC following gene deletion of Lox and 8 weeks of HFD. LOX knockout SMCs also had lower expression of Frzb and were more resistant to osteoblastic transformation in vitro. Conclusions: Vascular inactivation of LOX protects the vasculature from the proatherogenic effects of FRZB in SMCs

c-Kit expression in smooth muscle cells reduces atherosclerosis burden in hyperlipidemic mice

Increased receptor tyrosine kinase (RTK) activity has been historically linked to atherosclerosis. Paradoxically, we recently found that global deficiency in c-Kit function increased atherosclerosis in hyperlipidemic mice. This study aimed to investigate if such unusual atheroprotective phenotype depends upon c-Kit's function in smooth muscle cells (SMC). We studied atherosclerosis in a SMC-specific conditional knockout mice (KitSMC) and control littermate. Tamoxifen (TAM) and vehicle treated mice were fed high fat diet for 16 weeks before atherosclerosis assessment in the whole aorta using oil red staining. Smooth muscle cells were traced within the aortic sinus of conditional c-Kit tracing mice (KitSMC eYFP) and their control littermates (KitWT eYFP) by immunofluorescent confocal microscopy. We then performed RNA sequencing on primary SMC from c-Kit deficient and control mice, and identified significantly altered genes and pathways as a result of c-Kit deficiency in SMC. Atherosclerosis significantly increased in KitSMC mice with respect to control groups. In addition, the loss of c-Kit in SMC increased plaque size and necrotic core area in the aortic sinus of hyperlipidemic mice. Smooth muscle cells from KitSMC eYFP mice were more prone to migrate and express foam cell markers (e.g., Mac2 and MCAM) than those from control littermate animals. RNAseq analysis showed a significant upregulation in genes associated with cell proliferation, migration, lipid metabolism, and inflammation secondary to the loss of Kit function in primary SMCs. Loss of c-Kit increases SMC migration, proliferation, and expression of foam cell markers in atherosclerotic plaques from hyperlipidemic mice. [Display omitted] •c-Kit, a well-known stem cell marker, plays an important role in smooth muscle cells.•c-Kit deficiency increases smooth muscle cell migration to atherosclerotic lesions.•c-Kit deficiency increases smooth muscle cell-derived foam-cell formation.•c-Kit expression decreases atherosclerosis unlike other receptor tyrosine kinases

Abstract 15806: The Unique Cellular Ecosystem of the Human Basilic Vein: A Single-Cell Transcriptomic Analysis

Byline: Miguel G Rojas, Surgery, Univ of Miami, FL; Laisel Martinez, UNIVERSITY OF MIAMI, Miami, FL; Simone Pereira-Simon, Univ of Miami, Miami, FL; Zachary Zigmond, Univ of Miami, Miami, FL; Nieves Santos Falcon, Univ of Miami, Miami, FL; Alghidak Salama, Surgery, Univ of Miami, FL; Roberto I Vazquez-Padron, UNIVERSITY OF MIAMI, Miami, FL Introduction: The cells in veins that contribute to vascular disease have not been fully characterized. This study generated a cellular atlas of the human basilic vein that will help understand vein physiology and pathologies. Methods: Single-cell sequencing of four basilic veins from healthy organ donors. Results: The integrated single-cell profile of 15,747 vein cells revealed 13 populations containing canonical and non-canonical vascular markers. The SMC population represented 16% of cells, of which 8% were purely contractile and the remaining 8% had a modulated phenotype. One cluster of modulated SMCs expressed ECM genes (collagen type IV, FN1, and TNC) while retaining high expression of contractile markers (DES, MYH11, ©ÀACTG2). The other SMC cluster had unique expression of CD36, APOE, LPL, and STEAP4, characteristic of lipid-processing cells. Surprisingly, these non-diseased veins contained a high number of resident immune cells, including pro-inflammatory macrophages (9%), CD163- and HMOX1-expressing Mhem-like macrophages (18%), lymphocytes (5%), and small counts of neutrophils (0.3%) and mast cells (0.7%). The adventitial cell populations highlighted the fundamental role of this layer in vascular maintenance, remodeling, and angiogenesis. We found a significant number of vasa vasorum ECs (6.5%) which differentiated from the luminal subpopulation (3.5%) by CD34, KDR, NOTCH4, and ICAM2 expression. There were also two types of fibroblasts. Classical fibroblasts (19%) had high expression of collagen genes, while adipogenic fibroblasts (21%) were characterized by high levels of ECM-interacting fibulins, adipocyte-associated genes (ADH1B, APOD, CXCL14, IGF1), and modulators of angiogenesis (ADM and EFEMP1). CellCall analyses identified 46 overrepresented ligand-receptor communication pathways in all clusters, including CXCL, FGF, IL-6, and complement signaling. Communication between pro-inflammatory macrophages and luminal ECs was the most overrepresented signaling connection. Conclusions: This comprehensive atlas of the human vein will help identify cell subpopulations relevant to venous pathologies, without relying on extrapolations from arterial biology and focusing instead on the uniqueness of vein tissues.Professiona