Faculty Bibliography

Over the past decade, there has been a change in the epidemiology of oral cavity squamous cell cancer (OC-SCC). Many new cases of OC-SCC lack the recognized risk factors of smoking, alcohol and human papilloma virus. The aim of this study was to determine if the oral microbiome may be associated with OC-SCC in nonsmoking HPV negative patients. We compared the oral microbiome of HPV-negative nonsmoker OC-SCC( n=18), premalignant lesions(PML) (n=8) and normal control patients (n=12). Their oral microbiome was sampled by oral wash and defined by 16S rRNA gene sequencing. We report that the periodontal pathogens Fusobacterium, Prevotella, Alloprevotella were enriched while commensal Streptococcus depleted in OC-SCC. Based on the four genera plus a marker genus Veillonella for PML, we classified the oral microbiome into two types. Gene/pathway analysis revealed a progressive increase of genes encoding HSP90 and ligands for TLRs 1, 2 and 4 along the controls→PML→OC-SCC progression sequence. Our findings suggest an association between periodontal pathogens and OC-SCC in non smoking HPV negative patients.

BACKGROUND AND AIMS/OBJECTIVE:Platelets are a major culprit in the pathogenesis of cardiovascular disease (CVD). Circulating monocyte-platelet aggregates (MPA) represent the crossroads between atherothrombosis and inflammation. However, there is little understanding of the platelets and monocytes that comprise MPA and the prevalence of MPA in different CVD phenotypes. We aimed to establish (1) the reproducibility of MPA over time in circulating blood samples from healthy controls, (2) the effect of aspirin, (3) the relationship between MPA and platelet activity and monocyte subtype, and (4) the association between MPA and CVD phenotype (coronary artery disease, peripheral artery disease [PAD], abdominal aortic aneurysm, and carotid artery stenosis). METHODS AND RESULTS/RESULTS:platelets in healthy subjects and in patients with CVD. We found that MPA did not significantly differ over time in healthy controls, nor altered by aspirin use. Compared with healthy controls, MPA were significantly higher in CVD (9.4% [8.2, 11.1] vs. 21.8% [11.5, 44.1], p < 0.001) which remained significant after multivariable adjustment (β = 9.1 [SER = 3.9], p = 0.02). We found PAD to be associated with a higher MPA in circulation (β = 19.3 [SER = 6.0], p = 0.001), and among PAD subjects, MPA was higher in subjects with critical limb ischemia (34.9% [21.9, 51.15] vs. 21.6% [15.1, 40.6], p = 0.0015), and significance remained following multivariable adjustment (β = 14.77 (SE = 4.35), p = 0.001). CONCLUSIONS:Circulating MPA are a robust marker of platelet activity and monocyte inflammation, unaffected by low-dose aspirin, and are significantly elevated in subjects with CVD, particularly those with PAD.

OBJECTIVES/OBJECTIVE:This study determined if radical plakophilin-2 (PKP2) variants might underlie some cases of clinically diagnosed catecholaminergic polymorphic ventricular tachycardia (CPVT) and exercise-associated, autopsy-negative sudden unexplained death in the young (SUDY). BACKGROUND:Pathogenic variants in PKP2 cause arrhythmogenic right ventricular cardiomyopathy (ARVC). Recently, a cardiomyocyte-specific PKP2 knockout mouse model revealed that loss of PKP2 markedly reduced expression of genes critical in intracellular calcium handling. The mice with structurally normal hearts exhibited isoproterenol-triggered polymorphic ventricular arrhythmias that mimicked CPVT. METHODS:A PKP2 gene mutational analysis was performed on DNA from 18 unrelated patients (9 males; average age at diagnosis: 19.6 ± 12.8 years) clinically diagnosed with CPVT but who were RYR2-, CASQ2-, KCNJ2-, and TRDN-negative, and 19 decedents with SUDY during exercise (13 males; average age at death: 14 ± 3 years). Only radical (i.e., frame-shift, canonical splice site, or nonsense) variants with a minor allele frequency of ≤0.00005 in the genome aggregation database (gnomAD) were considered pathogenic. RESULTS:). Cardiac imaging or autopsy demonstrated a structurally normal heart in all patients at the time of their CPVT diagnosis or sudden death. CONCLUSIONS:Our data suggested that the progression of the PKP2-dependent electropathy can be independent of structural perturbations and can precipitate exercise-associated sudden cardiac arrest or sudden cardiac death before the presence of overt cardiomyopathy, which clinically mimics CPVT, similar to the PKP2 knockout mouse model. Thus, CPVT and SUDY genetic test panels should now include PKP2.

Calcium homeostasis in the lumen of the endoplasmic reticulum is required for correct processing and trafficking of transmembrane proteins, and defects in protein trafficking can impinge on cell signaling pathways. We show here that mutations in the endoplasmic reticulum calcium pump SERCA disrupt Wingless signaling by sequestering Armadillo/β-catenin away from the signaling pool. Armadillo remains bound to E-cadherin, which is retained in the endoplasmic reticulum when calcium levels there are reduced. Using hypomorphic and null SERCA alleles in combination with the loss of the plasma membrane calcium channel Orai allowed us to define three distinct thresholds of endoplasmic reticulum calcium. Wingless signaling is sensitive to even a small reduction, while Notch and Hippo signaling are disrupted at intermediate levels, and elimination of SERCA function results in apoptosis. These differential and opposing effects on three oncogenic signaling pathways may complicate the use of SERCA inhibitors as cancer therapeutics.

Interactions between axons and Schwann cells are essential for the acquisition of Schwann cell radial and longitudinal polarity and myelin sheath assembly. In the internode, the largest of these longitudinal domains, axon-Schwann cell interactions are mediated by the Nectin-like (Necl) cell adhesion proteins, also known as SynCAMs or Cadms. In particular, Necl-1/Cadm3 expressed on the axon surface binds to Necl-4/Cadm4 expressed along the adaxonal membrane of myelinating Schwann cells. Necl-4 promotes myelination in vitro and is required for the timely onset of myelination and the fidelity of the organization of the myelin sheath and the internode in vivo. A key question is the identity of the downstream effectors of Necl-4 that mediate its effects. The cytoplasmic terminal region (CTR) of Necl-4 contains a PDZ-domain binding motif. Accordingly, we used the CTR of Necl-4 in an unbiased proteomic screen of PDZ-domain proteins. We identify Par-3, a multi-PDZ domain containing protein of the Par-aPKC polarity complex previously implicated in myelination, as an interacting protein. Necl-4 and Par-3 are colocalized along the inner Schwann cell membrane and coprecipitate from Schwann cell lysates. The CTR of Necl-4 binds to the first PDZ domain of Par-3 thereby recruiting Par-3 to sites of Necl-4/Necl-1 interaction. Knockdown of Necl-4 perturbs Par-3 localization to the inner membrane of Schwann cells in myelinating co-cultures. These findings implicate interactions of Necl-1/Necl-4 in the recruitment of Par-3 to the Schwann cell adaxonal membrane and the establishment of Schwann cell radial polarity.

Endometriosis - a disease causing pain and infertility - is encountered in nearly 50% of infertile women. While medical treatment is effective on pain and recurrence of symptoms after surgical excision, it is of no help for treating infertility for which the only options considered are surgery and ART. Surgery enhances the chances of conceiving naturally during the 12-18 ensuing months irrespective of the stage of the disease. Surgery however is of no help when ART is considered, as it does not improve outcome and can only harm the ovarian response to stimulation. Today therefore, ART is commonly the primary option to be considered in women whose infertility is associated with endometriosis and whose ovarian reserve is compromised and/or who are over 35 years of age. When, ART is envisioned it is best to opt for a segmented ART approach with agonist trigger, freeze all and deferred embryo transfer.

In diabetes, stromal cell-derived factor-1 (SDF-1) expression and progenitor cell recruitment are reduced. Dipeptidyl peptidase-4 (DPP-4) inhibits SDF-1 expression and progenitor cell recruitment. Here we examined the impact of the DPP-4 inhibitor, MK0626, on progenitor cell kinetics in the context of wound healing. Wildtype (WT) murine fibroblasts cultured under high-glucose to reproduce a diabetic microenvironment were exposed to MK0626, glipizide, or no treatment, and SDF-1 expression was measured with ELISA. Diabetic mice received MK0626, glipizide, or no treatment for 6 weeks and then were wounded. Immunohistochemistry was used to quantify neovascularization and SDF-1 expression. Gene expression was measured at the RNA and protein level using quantitative polymerase chain reaction and ELISA, respectively. Flow cytometry was used to characterize bone marrow-derived mesenchymal progenitor cell (BM-MPC) population recruitment to wounds. BM-MPC gene expression was assayed using microfluidic single cell analysis. WT murine fibroblasts exposed to MK0626 demonstrated increased SDF-1 expression. MK0626 treatment significantly accelerated wound healing and increased wound vascularity, SDF-1 expression, and dermal thickness in diabetic wounds. MK0626 treatment increased the number of BM-MPCs present in bone marrow and in diabetic wounds. MK0626 had no effect on BM-MPC population dynamics. BM-MPCs harvested from MK0626-treated mice exhibited increased chemotaxis in response to SDF-1 when compared to diabetic controls. Treatment with a DPP-4 inhibitor significantly improved wound healing, angiogenesis, and endogenous progenitor cell recruitment in the setting of diabetes.