Faculty Bibliography

[Figure: see text].

Endothelial cells play a key role in the regulation of disease. Defective regulation of endothelial cell homeostasis may cause mesenchymal activation of other endothelial cells or neighboring cell types, and in both cases contributes to organ fibrosis. Regulatory control of endothelial cell homeostasis is not well studied. Diabetes accelerates renal fibrosis in mice lacking the endothelial glucocorticoid receptor (GR), compared to control mice. Hypercholesterolemia further enhances severe renal fibrosis. The fibrogenic phenotype in the kidneys of diabetic mice lacking endothelial GR is associated with aberrant cytokine and chemokine reprogramming, augmented Wnt signaling and suppression of fatty acid oxidation. Both neutralization of IL-6 and Wnt inhibition improve kidney fibrosis by mitigating mesenchymal transition. Conditioned media from endothelial cells from diabetic mice lacking endothelial GR stimulate Wnt signaling-dependent epithelial-to-mesenchymal transition in tubular epithelial cells from diabetic controls. These data demonstrate that endothelial GR is an essential antifibrotic molecule in diabetes.

BACKGROUND:With the exponential increase in the use of endovascular techniques in the treatment of peripheral artery disease, our understanding of factors that affect intervention failures continues to grow. We sought to assess the outcomes of percutaneous transluminal angioplasty for isolated de novo superficial femoral artery (SFA) disease based on balloon diameter. METHODS:The Vascular Quality Initiative database was queried for patients undergoing percutaneous balloon angioplasty for isolated de novo atherosclerotic SFA disease. Based on the diameter of the angioplasty balloon as a surrogate measure of arterial diameter, patients were stratified into two groups: group 1, balloon diameter < 5 mm (354 patients) and group 2, balloon diameter ≥ 5 mm (1,550 patients). The primary patency and major adverse limb event (MALE) were estimated by the Kaplan-Meier method and compared with the log-rank test, based on vessel diameter. multivariable Cox regression analysis was used to determine factors associated with the primary patency. RESULTS:From January 2010 through December 2018, a total of 1,904 patients met criteria for analysis, with a mean follow-up of 13.3 ± 4.5 months. The mean balloon diameters were 3.92 ± 0.26 mm and 5.47 ± 0.55 mm in group 1 and 2, respectively (P<.001). The mean length of treatment and distribution of TASC lesions were not statistically different between the groups. Primary patency at 18 months was significantly lower in group 1, compared with group 2 (55% vs 67%; log-rank P<.001). The MALE rate was higher in group 1 than group 2 (33% vs 26%; log-rank P<.001). Among patients with claudication, there was no significant difference in the primary patency (61% vs 68%; log-rank P=.073) and MALE (27% vs 22%; log-rank P=.176) at 18 months between groups 1 and 2, respectively. However, in patients with CLTI, group 1 had significantly lower 18-month primary patency (47% vs 64%; log-rank P<.014) and higher MALE rates (41% vs 35%; log-rank P=.012) than group 2. Cox proportional hazard analysis confirmed that balloon diameter < 5 mm was independently associated with increased risks of primary patency loss (HR 1.35; 95% CI, 1.04-1.72; P=.021) and MALE (HR 1.29; 95% CI, 1-1.67; P=.048) at 18-months. CONCLUSIONS:In patients undergoing isolated SFA balloon angioplasty for CLTI, smaller SFA (< 5mm) was associated with worse primary patency and MALE. Using balloon size as a surrogate, our findings suggest that patients with a smaller SFA diameter appear to be at increased risk for treatment failure and warrant closer surveillance. Furthermore, these patients may also be considered for alternative approaches, including open revascularization.

Telomere length control is critical for cellular lifespan and tumor suppression. Telomerase is transiently activated in the inner cell mass of the developing blastocyst to reset telomere reserves. Its silencing upon differentiation leads to gradual telomere shortening in somatic cells. Here, we report that transcriptional regulation through cis-regulatory elements only partially accounts for telomerase activation in pluripotent cells. Instead, developmental control of telomerase is primarily driven by an alternative splicing event, centered around hTERT exon 2. Skipping of exon 2 triggers hTERT mRNA decay in differentiated cells, and conversely, its retention promotes telomerase accumulation in pluripotent cells. We identify SON as a regulator of exon 2 alternative splicing and report a patient carrying a SON mutation and suffering from insufficient telomerase and short telomeres. In summary, our study highlights a critical role for hTERT alternative splicing in the developmental regulation of telomerase and implicates defective splicing in telomere biology disorders.

Skin scarring, the end result of adult wound healing, is detrimental to tissue form and function. Engrailed-1 lineage-positive fibroblasts (EPFs) are known to function in scarring, but Engrailed-1 lineage-negative fibroblasts (ENFs) remain poorly characterized. Using cell transplantation and transgenic mouse models, we identified a dermal ENF subpopulation that gives rise to postnatally derived EPFs by activating Engrailed-1 expression during adult wound healing. By studying ENF responses to substrate mechanics, we found that mechanical tension drives Engrailed-1 activation via canonical mechanotransduction signaling. Finally, we showed that blocking mechanotransduction signaling with either verteporfin, an inhibitor of Yes-associated protein (YAP), or fibroblast-specific transgenic YAP knockout prevents Engrailed-1 activation and promotes wound regeneration by ENFs, with recovery of skin appendages, ultrastructure, and mechanical strength. This finding suggests that there are two possible outcomes to postnatal wound healing: a fibrotic response (EPF-mediated) and a regenerative response (ENF-mediated).

Staphylococcus aureus has evolved into diverse lineages, known as clonal complexes (CCs), which exhibit differences in the coding sequences of core virulence factors. Whether these alterations affect functionality is poorly understood. Here, we studied the highly polymorphic pore-forming toxin LukAB. We discovered that the LukAB toxin variants produced by S. aureus CC30 and CC45 kill human phagocytes regardless of whether CD11b, the previously established LukAB receptor, is present, and instead target the human hydrogen voltage-gated channel 1 (HVCN1). Biochemical studies identified the domain within human HVCN1 that drives LukAB species specificity, enabling the generation of humanized HVCN1 mice with enhanced susceptibility to CC30 LukAB and to bloodstream infection caused by CC30 S. aureus strains. Together, this work advances our understanding of an important S. aureus toxin and underscores the importance of considering genetic variation in characterizing virulence factors and understanding the tug of war between pathogens and the host.

BACKGROUND/OBJECTIVES/OBJECTIVE:To investigate the evaluation and management of atopic dermatitis (AD) in the pediatric emergency department (PED). METHODS:This retrospective chart review was performed at the PED of a single institution and examined data from 2012 to 2017. Of 335 visits from patients 18 years and younger coded for AD, 167 visits with documented findings that supported a diagnosis of AD according to guidelines from the American Academy of Dermatology were included. RESULTS:The mean age of presentation was 6.3 years (standard deviation [SD]: 5.9). Of 11 patients with multiple visits, the mean between-visit interval was 31 days (SD: 41). Topical corticosteroids (TCSs) were not prescribed or recommended in 63/167 visits. In an additional 46/167 visits, over-the-counter topical hydrocortisone was recommended. Of prescribed TCS, the mean TCS class was 5.5 (SD: 1.9). 61/104 recommended or prescribed TCSs were weak (Class 7), the most likely used class (P < .001). Dermatology consultation was requested in 14/167 visits and was associated with higher rates of TCS prescriptions (13/14 vs 91/153, P = .018), a higher mean class of TCS prescribed (3.1 vs 5.9, P < .001), higher prescription rates of systemic antibiotics (8/14 vs 10/153, P < .001), and higher recommendation rates for emollient usage (10/14 vs 46/153, P = .005). CONCLUSIONS:Most patients presenting to the PED for AD were either not prescribed a TCS or were prescribed a weak TCS, often one that is over-the-counter. While there may be a variety of explanations for these findings, it is possible they reveal a practice gap regarding AD management in the PED.

Human chromosome 9p21.3 is susceptible to inactivation in cell immortalization and diseases, such as cancer, coronary artery disease and type-2 diabetes. Although this locus encodes three cyclin-dependent kinase (CDK) inhibitors (p15^INK4B, p14^ARF and p16^INK4A), our understanding of their functions and modes of action is limited to the latter two. Here, we show that in vitro p15^INK4B is markedly stronger than p16^INK4A in inhibiting pRb1 phosphorylation, E2F activity and cell-cycle progression. In mice, urothelial cells expressing oncogenic HRas and lacking p15^INK4B, but not those expressing HRas and lacking p16^INK4A, develop early-onset bladder tumors. The potency of CDKN2B/p15^INK4B in tumor suppression relies on its strong binding via key N-terminal residues to and inhibition of CDK4/CDK6. p15^INK4B also binds and inhibits enolase-1, a glycolytic enzyme upregulated in most cancer types. Our results highlight the dual inhibition of p15^INK4B on cell proliferation, and unveil mechanisms whereby p15^INK4B aberrations may underpin cancer and non-cancer conditions.

Despite a decline in popularity over the last several decades, cigarette smoking remains a leading cause of cardiovascular morbidity and mortality. Yet, the effects of cigarette smoking on vascular structure and function are largely unknown. To evaluate changes in the mechanical properties of the aorta that occur with chronic smoking, we exposed female Apolipoprotein E-deficient mice to mainstream cigarette smoke daily for 24 weeks, with room air as control. By the time of sacrifice, cigarette-exposed mice had lower body mass, but experienced larger systolic/diastolic blood pressure when compared to controls. Smoking was associated with significant wall thickening, reduced axial stretch, and circumferential material softening of the aorta. While this contributed to maintaining intrinsic tissue stiffness at control levels despite larger pressure loads, the structural stiffness became significantly larger. Furthermore, the aorta from cigarette-exposed mice exhibited decreased ability to store elastic energy and augment diastolic blood flow. Histological analysis revealed a region-dependent increase in the cross-sectional area due to smoking. Increased smooth muscle and extracellular matrix content led to medial thickening in the ascending aorta, while collagen deposition increased the thickness of the descending thoracic and abdominal aorta. Atherosclerotic lesions were larger in exposed vessels and featured a necrotic core overlaid by a thinned fibrous cap and macrophage infiltration, consistent with a vulnerable phenotype. Collectively, our data indicate that cigarette smoking decreases the mechanical functionality of the aorta, inflicts morphometric alterations to distinct segments of the aorta, and accelerates the progression of atherosclerosis.

Binding of Streptococcus pneumoniae (Spn) to nasal mucus leads to entrapment and clearance via mucociliary activity during colonization. To identify Spn factors allowing for evasion of mucus binding, we used a solid-phase adherence assay with immobilized mucus of human and murine origin. Spn bound large mucus particles through interactions with carbohydrate moieties. Mutants lacking neuraminidase A (nanA) or neuraminidase B (nanB) showed increased mucus binding that correlated with diminished removal of terminal sialic acid residues on bound mucus. The non-additive activity of the two enzymes raised the question why Spn expresses two neuraminidases and suggested they function in the same pathway. Transcriptional analysis demonstrated expression of nanA depends on the enzymatic function of NanB. As transcription of nanA is increased in the presence of sialic acid, our findings suggest that sialic acid liberated from host glycoconjugates by the secreted enzyme NanB induces the expression of the cell-associated enzyme NanA. The absence of detectable mucus desialylation in the nanA mutant, in which NanB is still expressed, suggests that NanA is responsible for the bulk of the modification of host glycoconjugates. Thus, our studies describe a functional role for NanB in sialic acid sensing in the host. The contribution of the neuraminidases in vivo was then assessed in a murine model of colonization. Although mucus-binding mutants showed an early advantage, this was only observed in a competitive infection, suggesting a complex role of neuraminidases. Histologic examination of the upper respiratory tract demonstrated that Spn stimulates mucus production in a neuraminidase-dependent manner. Thus, an increase production of mucus containing secretions appears to be balanced, in vivo, by decreased mucus binding. We postulate that through the combined activity of its neuraminidases, Spn evades mucus binding and mucociliary clearance, which is needed to counter neuraminidase-mediated stimulation of mucus secretions.