Faculty Bibliography

The purpose of this investigation was to determine the role of extracellular vesicles (EVs), released from articular chondrocytes in a physiological or pathological state, in cell-cell communication with other articular chondrocytes or chondrocytic precursor cells. Conditioned medium from interleukin-1beta (IL-1β)-treated human articular chondrocytes stimulated catabolic events and inhibited type II collagen expression in articular chondrocytes to a much greater degree than medium from IL-1β-treated chondrocytes after complete removal of EVs. Vehicle-treated and IL-1β-treated human articular chondrocytes released EVs of similar size; however the number of EVs released by IL-1β-treated chondrocytes was markedly higher than the number of EVs released from vehicle-treated cells. Furthermore, our findings demonstrate that similar to medium from IL-1β-treated chondrocytes containing EVs, EVs isolated from medium of IL-1β-treated chondrocytes stimulated catabolic events in articular chondrocytes, whereas EVs isolated from the medium of vehicle-treated chondrocytes inhibited catabolic events and increased mRNA levels of aggrecan and type II collagen in IL-1β-treated chondrocytes. Furthermore, medium containing EVs from vehicle-treated articular chondrocytes or EVs isolated from this medium stimulated chondrogenesis of C3H10T1/2 cells, whereas medium containing EVs from IL-1β-treated chondrocytes or EVs isolated from this medium inhibited chondrogenesis. Our findings suggest that EVs released by articular chondrocytes play a key role in the communication between joint cells and ultimately in joint homeostasis, maintenance, pathology, and repair. This article is protected by copyright. All rights reserved.

BACKGROUND:Pressure injury is seen across all healthcare settings and affects people of any age and health condition. It imposes a significant burden, with annual costs of up to $17.8 billion in the United States alone. Despite considerable resources it exhausts, the disease remains very prevalent, and the incidence is on the rise. This is in part due to aging population, growing number of nursing home residents, poorly understood biology, and dismal track record of clinical research in this field. METHODS:In our Review Article, we discuss the disease pathophysiology, clinical manifestation, evidence based recommendations for risk assessment, prevention and timely management, existing challenges, and directions to improve research on the field. This article encompasses dedicated sections on the full spectrum of the pressure related pathologies including "conventional pressure ulcers", "medical device related pressure injuries", "pressure injuries in mucosal membranes", "pressure injuries in pediatric population", "pressure injury at end of life", and the "role of pressure in pathogenesis of diabetic foot ulcers".

Purpose: A hallmark of age-related macular degeneration is the accumulation of deposits of lipids and proteins, called drusen, in Bruch's membrane. Several culture models of retinal pigment epithelia (RPE) develop drusen-like deposits. We examined whether prolonged culture of RPE with a retina-like tissue affected the number or size of these deposits.Methods: RPE and retinal progenitor cells (RPC) were differentiated from induced pluripotent stem cells derived from fetal tissue and maintained in serum-free medium containing the B27 supplement. RPE was cultured on Transwell filter inserts, and RPC were cultured on a planar matrix composed of gelatin, hyaluronic acid, and chondroitin sulfate. After seeding the filter, RPC were layered on top of the RPE. RPE ± RPC were cultured for six months. The function of RPE tight junctions was assessed by the transepithelial electrical resistance. Cultures were stained for actin, neutral lipids, APOE, TIMP3, vitronectin, and calcium deposits. Morphometric analysis was used to determine the number and volume of the "druse".Results: After six months, the TER was greater for the co-cultures (304±11 Ω×cm² vs 243±7 Ω×cm², p<0.01). RPE formed mounds of druse-like deposits that contained, vitronectin, APOE, TIMP3 and calcium deposits, but lipids were undetected. The mounds overlay areas of the filter where no lipid was detected in the pores, and the RPE overlying the mounds was often thin. The number of "druse"/100,000μm² was 5.0±0.4 (co-cultures) vs 2.3±0.1 (monocultures) (p<0.05). The total volume of "drusen"/100,000μm³ was 15,133±1544 (co-cultures) vs 5,993±872 (monocultures) (p<0.05). There was no statistical difference between the size-distribution of druse-like particles formed by each culture.Conclusions: Covering the apical membrane of RPE with a thick tissue increased the number of druse-like deposits. The apparent size limitation of the deposits may reflect the apparent interruption of the of lipid cycle found at the basal membrane of the RPE.

Long interspersed element-1 (LINE-1, L1) sequences, which comprise about 17% of human genome, are the product of one of the most active types of mobile DNAs in modern humans. LINE-1 insertion alleles can cause inherited and de novo genetic diseases, and LINE-1-encoded proteins are highly expressed in some cancers. Genome-wide LINE-1 mapping in single cells could be useful for defining somatic and germline retrotransposition rates, and for enabling studies to characterize tumour heterogeneity, relate insertions to transcriptional and epigenetic effects at the cellular level, or describe cellular phylogenies in development. Our laboratories have reported a genome-wide LINE-1 insertion site mapping method for bulk DNA, named transposon insertion profiling by sequencing (TIPseq). There have been significant barriers applying LINE-1 mapping to single cells, owing to the chimeric artefacts and features of repetitive sequences. Here, we optimize a modified TIPseq protocol and show its utility for LINE-1 mapping in single lymphoblastoid cells. Results from single-cell TIPseq experiments compare well to known LINE-1 insertions found by whole-genome sequencing and TIPseq on bulk DNA. Among the several approaches we tested, whole-genome amplification by multiple displacement amplification followed by restriction enzyme digestion, vectorette ligation and LINE-1-targeted PCR had the best assay performance. This article is part of a discussion meeting issue 'Crossroads between transposons and gene regulation'.

During obesity, macrophages infiltrate the visceral adipose tissue and promote inflammation that contributes to type II diabetes. Evidence suggests that the rewiring of cellular metabolism can regulate macrophage function. However, the metabolic programs that characterize adipose tissue macrophages (ATM) in obesity are poorly defined. Here, we demonstrate that ATM from obese mice exhibit metabolic profiles characterized by elevated glycolysis and oxidative phosphorylation, distinct from ATM from lean mice. Increased activation of HIF-1α in ATM of obese visceral adipose tissue resulted in induction of IL-1β and genes in the glycolytic pathway. Using a hypoxia-tracer, we show that HIF-1α nuclear translocation occurred both in hypoxic and non-hypoxic ATM suggesting that both hypoxic and pseudohypoxic stimuli activate HIF-1α and its target genes in ATM during diet-induced obesity. Exposure of macrophages to the saturated fatty acid palmitate increased glycolysis and HIF-1α expression, which culminated in IL-1β induction thereby simulating pseudohypoxia. Using mice with macrophage-specific targeted deletion of HIF-1α, we demonstrate the critical role of HIF-1α-derived from macrophages in regulating ATM accumulation, and local and systemic IL-1β production, but not in modulating systemic metabolic responses. Collectively, our data identify enhanced glycolysis and HIF-1α activation as drivers of low-grade inflammation in obesity.

Background Psoriasis is an inflammatory disease of the skin associated with heightened cardiovascular (CV) disease. Serum levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) associates with future CV risk and vascular dysfunction. We aimed to identify the relationship between pro-inflammatory pathways, circulating PCSK9, and vascular health in psoriasis. Methods Whole blood transcriptomics and serum proteomics was performed in 20 patients with psoriasis (mean age 42 +/- 14 years, 55% male, psoriasis area and severity index [PASI] 5 [3 - 11]) and 15 controls (mean age 41 +/- 14 years, 53% male) recruited into a clinical trial to assess vascular health in psoriasis (NCT03228017). Vascular health was assessed through flow mediated dilatation (FMD) and harvesting and analysis of brachial vein endothelial cells. Results Circulating PCSK9 was found to be 1.13-fold higher in psoriasis compared to controls (p=0.02) despite no difference in LDL-C (108 +/- 38 mg/dl vs. 90 +/- 25 mg/dl, respectively p=0.31). Circulating PCSK9 was correlated with psoriasis area severity index (PASI score, r=0.43, p=0.04) even after adjustment for age, gender, BMI and LDL-C (beta=0.02, p=0.03). Integration of the whole blood transcriptome yielded 322 transcripts which correlated with circulating PCSK9 (FDR<0.05). Network analysis of these transcripts highlighted interferon signaling (p=7.2x10^-6), a known pathogenic process in psoriasis, as a key regulator of PCSK9. Finally, circulating PCSK9 positively correlated with brachial vein endothelial expression of the pro-inflammatory transcripts CXCL10 (r=0.69, p<0.001), ICAM1 (r=0.49, p=0.02) and IL1beta (r=0.38, p<0.01) and inversely correlated with the functional measure of endothelial health, FMD (r=-0.52, p=0.03). Conclusion Circulating PCSK9 is elevated in psoriasis and associated with impaired vascular health. Analysis of the relationship between PCSK9 and systemic pathways revealed prominent interactions between PCSK9 and interferon signaling. Further research to better characterize these transcriptome and proteome variations and how it impacts vascular health in psoriasis may help elucidate new targets for therapeutic interventions.
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Background Transesophageal echocardiography (TEE) is the gold standard for determining mitral regurgitant (MR) leaflet morphology and suitability for edge-to-edge (E2E) repair. Computed tomography (CT) has become essential for evaluation for transcatheter mitral valve replacement (TMVR) and has the temporal and spatial resolution to show leaflet abnormalities with great clarity (figure) but the correlation of findings with TEE has not been well studied. Methods A consecutive series of patients attending clinic for moderate-severe or greater mitral regurgitation underwent CT and TEE. Data was analyzed for leaflet morphology with blinded independent analyses by CT and TEE expert readers. Results A study flow diagram is shown (figure). Mean age was 79.6 (SD 10.9) and mean STS score (repair) was 4.8% (SD3.7). Analyses were independently performed (figure). There was a strong correlation between mitral valve orifice area (MVOA) by CT and TEE (r=0.86, p<0.001), however MVOA was on average 0.45 cm² larger (p=0.003) on CT (5.24cm², SD 1.84) than TEE (4.79cm², SD 1.91). For those cases where CT could make an interpretation on suitability for E2E repair there was 100% concordance between CT and TEE (figure). Conclusion In this preliminary retrospective analysis, a comparison of CT and TEE suggested that CT may be a useful non-invasive modality for the assessment of mitral leaflet morphology and suitability for E2E repair. A prospective comparison is ongoing and will be completed at the time of presentation. [Figure presented]
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Background Computed tomography (CT) has become the standard of care for assessment for the suitability for transcatheter mitral valve replacement (TMVR); however, variation in mitral annular measurements across the cardiac cycle has thus far been poorly studied. Because of this, currently TMVR assessment is cumbersome and involves the assessment of multiple phases. We sought to further understand variation in mitral annular dimensions with the cardiac cycle and assess its potential implications for Methods A total of 118 patients presented to the heart valve clinic and underwent CT for possible TMVR assessment and were consecutively studied with multiphase CT. The mitral annulus was measured in 10 phases using 3mensio mitral planning software and several parameters collected including perimeter, area, anterior-posterior (AP) dimension and commissure-commissure (CC) dimension. Results Of the 118 patients screened, 83.9% had predominant MR, 10.2% mixed MS/MR and 5.9% predominant MS. Changes in perimeter, Area, AP and CC dimensions are shown (figure). Comparison of largest and smallest mean measurements for each phase for perimeter, Area, AP and CC dimensions showed a 2.02%, 4.36%, 8.09% and 2.86% variation respectively. Conclusion In contrast to the dynamism of the aortic annulus and neo-LVOT, the mitral annulus does not vary significantly. This may allow limitation of radiation restricting CT acquisitions to mid-systole where the neo-LVOT is smallest. [Figure presented]
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Background Transfemoral (TF) Transcatheter Aortic Valve Replacement (TAVR) has been shown to be at least equivalent to surgery. Nevertheless, many patients do not qualify for TF approach due to severe ilio-femoral (I-F) occlusive disease. The use of an atherectomy device in order to facilitate TF-TAVR has only been reported in case reports. We describe our experience using orbital atherectomy in preparation for TF-TAVR. Methods We searched our prospective database for the last 1000 TAVR procedures. Patient demographics, procedural characteristics, CT characteristics and short-term outcomes were recorded. CT scans were reviewed to assess access. Hostile access was defined as luminal size less than 5 mm, or less than 5.5mm and the presence of more than 270degree calcification. The primary end-point was the ability to successfully deliver a transcatheter valve via the intended, pre-treated access site. Secondary end-points were procedural vascular complications including mortality, stroke, bleeding requiring transfusion, and urgent vascular repair at 30 days. Results From April 2016 to July 2019, 1000 TAVR procedures were performed. Six subjects (0.6%) required alternative access; 68 patients (6.8%) were labeled as having a hostile I-F anatomy that required vessel preparation prior to TAVR. 48 (70.6%) had angioplasty only and 20 (29.4%) required atherectomy and angioplasty. Atherectomy was performed in a range of 5-21 days prior to TAVR; transradial approach was used in 90% of the time. Out of 20 patients treated with atherectomy successful TF delivery of the valve was achieved in 19 (95%). The mean vessel reference diameter in atherectomy group was 4.0+/-0.9mm. All had near-circumferential calcification. There was no in-hospital mortality or stroke. There were no perforations. One subject required placement of a self-expandable stent due to severe dissection. None of the end-points occurred between hospital discharge and 30-day follow-up. Conclusion Orbital atherectomy used for vessel preparation is a safe and very effective technique to facilitate TF-TAVR in patients with hostile peripheral anatomy.
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