Faculty Bibliography

Vitiligo, an acquired depigmentation disorder, results from autoimmune targeting of melanocytes. Vitiligo can be triggered following exposure to phenols such as monobenzone (MBEH) and 4-tertiary butyl phenol (4-TBP). Melanocytes from individuals with idiopathic vitiligo (trigger is not known) are more sensitive to MBEH and 4-TBP. We hypothesized that stress response pathways activated following exposure to vitiligo triggers may be dysregulated in individuals who develop the disorder. We delineated the response of melanocytes from normally pigmented individuals (NMs) to challenge with MBEH and 4-TBP and identified two key survival pathways activated following exposure: the NRF2-regulated antioxidant response and the unfolded protein stress response (UPR). NRF2 knockdown sensitized NMs to MBEH (p < 0.0001), while NRF2 activation by knockdown of its repressor KEAP significantly decreased sensitivity (p < 0.0001). Similarly, inhibition of the PERK-eIF2alpha arm of the UPR with the chemical inhibitor GSK2606414 increased sensitivity to MBEH (cleaved PARP observed at 250 muM MBEH with GSK2606414 and 400 muM without). Activation of NRF2-regulated antioxidant responses and PERK-mediated phosphorylation of eIF2alpha following MBEH exposure was impaired in melanocytes from individuals who developed vitiligo. We have thus identified two stress response pathways that may be dysfunctional in vitiligo and contribute to the onset of depigmentation

[PLACEHOLDER].

Background/UNASSIGNED:Osteomyelitis is a challenging infection that can involve 4-6 weeks of intravenous (IV) antibiotics. Dalbavancin, approved for acute bacterial skin and skin structure infections, has potent activity against gram-positive pathogens. This study assessed the efficacy and safety of dalbavancin as a 2-dose regimen for osteomyelitis. Methods/UNASSIGNED:This study was a randomized, open-label, comparator-controlled trial in adults with a first episode of osteomyelitis defined by clinical symptoms, radiologic findings, and elevated C-reactive protein. Patients were randomized 7:1 to dalbavancin (1500 mg IV on days 1 and 8) or standard of care (SOC) for osteomyelitis (oral or IV) per investigator judgment for 4-6 weeks. The primary endpoint was clinical response at day 42, defined as recovery without need for additional antibiotics in the clinically evaluable (CE) population. Clinical response was also assessed at day 21, 6 months, and 1 year. Results/UNASSIGNED:was the most common pathogen (60% of patients). Clinical cure at day 42 was seen in 65/67 (97%) and 7/8 (88%) patients in the dalbavancin group and SOC group in the CE population, respectively. Clinical response was similar in the dalbavancin group at day 21 (94%), 6 months, and 1 year (96%). Treatment-emergent adverse events occurred in 10 patients in the dalbavancin group; no patient discontinued treatment due to an adverse event. Conclusions/UNASSIGNED:A 2-dose regimen of weekly dalbavancin is effective and well tolerated for the treatment of osteomyelitis in adults. Clinical Trials Registration/UNASSIGNED:NCT02685033.

Ras is the best-studied member of the superfamily of small GTPases because of its role in cancer. Ras proteins transmit signals for proliferation, differentiation and survival. Three RAS genes encode 4 isoforms. All Ras isoforms have long been considered membrane bound, a localization required for function. Our recent study revealed that N-Ras differs from all other isoforms in being largely cytosolic even following modification with a prenyl lipid. Endogenous, cytosolic N-Ras chromatographed in both high and low molecular weight pools, a pattern that required prenylation, suggesting prenyl-dependent interaction with other proteins. VPS35, a coat protein of the retromer, was shown to interact with prenylated N-Ras in the cytosol. Silencing VPS35 results in partial N-Ras mislocalization on vesicular and tubulovesicular structures, reduced GTP-loading of Ras proteins, and inhibited proliferation and MAPK signaling in an oncogenic N-Ras-driven tumor cell line. Our data revealed a novel regulator of N-Ras trafficking and signaling.

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.

Immunosuppressive myeloid-derived suppressor cells (MDSC) subvert antitumor immunity and limit the efficacy of chimeric antigen receptor T cells (CAR-T). Previously, we reported that the GM-CSF/JAK2/STAT3 axis drives liver-associated MDSC (L-MDSC) proliferation and blockade of this axis rescued antitumor immunity. We extended these findings in our murine liver metastasis (LM) model, by treating tumor-bearing mice with STAT3 inhibitors (STATTIC or BBI608) to further our understanding of how STAT3 drives L-MDSC suppressive function. STAT3 inhibition caused significant reduction of tumor burden as well as L-MDSC frequencies due to decrease in pSTAT3 levels. L-MDSC isolated from STATTIC or BBI608-treated mice had significantly reduced suppressive function. STAT3 inhibition of L-MDSC was associated with enhanced antitumor activity of CAR-T. Further investigation demonstrated activation of apoptotic signaling pathways in L-MDSC following STAT3 inhibition as evidenced by an upregulation of the pro-apoptotic proteins Bax, cleaved caspase-3, and downregulation of the anti-apoptotic protein Bcl-2. Accordingly, there was also a decrease of pro-survival markers, pErk and pAkt, and an increase in pro-death marker, Fas, with activation of downstream JNK and p38 MAPK. These findings represent a previously unrecognized link between STAT3 inhibition and Fas-induced apoptosis of MDSCs. Our findings suggest that inhibiting STAT3 has potential clinical application for enhancing the efficacy of CAR-T cells in LM through modulation of L-MDSC.

Chronic inflammation drives many obesity-associated conditions, including atherosclerosis. GlycA, a marker of systemic inflammation with lower intraindividual variability than hsCRP, is independently associated with incident cardiovascular events and mortality. Although GlycA is elevated in obesity, correlations with anthropometric measures are modest and the effect of weight loss on GlycA is untested. Obese (BMI 44.6±6.6kg/m² ), non-diabetic women (33.7±8.2 years) undergoing Roux-en-Y gastric bypass (n=23) or sleeve gastrectomy (n=31) were prospectively studied at baseline, 6 and 12 months post-procedure. Women with normal BMI (n=14) served as controls. Bariatric surgery significantly reduced GlycA by 6 months (451±47umol/L vs 383±50umol/L; p<0.001) with further reduction at 12 months (348±41umol/L; p<0.001) and no difference between procedures. At 12 months, despite 41% of surgical subjects maintaining BMI >30kg/m² , GlycA levels did not differ between surgical and control subjects (p=0.13). Increased HDL particle size was strongly associated with reduced GlycA (r=-0.49; p<0.001) and was found to mediate up to 43% of its weight-loss-associated fall. This is the first study to demonstrate that surgical weight loss markedly reduces levels of GlycA.

Here, we report the draft genome of Streptococcus halitosis sp. nov. strain VT-4, a novel bacterium isolated from the dorsal part of the tongue of a patient with halitosis. The genome comprised 1,880,608 bp with a GC content of 41.0%. There were 1,782 predicted protein-coding genes, including those associated with virulence and antibiotic resistance.

Recent studies suggest that closely related species can accumulate substantial genetic and phenotypic differences despite ongoing gene flow, thus challenging traditional ideas regarding the genetics of speciation. Baboons (genus Papio) are Old World monkeys consisting of six readily distinguishable species. Baboon species hybridize in the wild, and prior data imply a complex history of differentiation and introgression. We produced a reference genome assembly for the olive baboon (Papio anubis) and whole-genome sequence data for all six extant species. We document multiple episodes of admixture and introgression during the radiation of Papio baboons, thus demonstrating their value as a model of complex evolutionary divergence, hybridization, and reticulation. These results help inform our understanding of similar cases, including modern humans, Neanderthals, Denisovans, and other ancient hominins.

The in vitro activity of sulopenem was assessed against a 2014-2016 collection of 539 urinary isolates of Escherichia coli from Canadian patients using CLSI-defined broth microdilution methodology. A concentration of sulopenem of 0.03 µg/ml inhibited both 50% (MIC₅₀) and 90% (MIC₉₀) of isolates tested; sulopenem MICs ranged from 0.015 to 0.25 µg/ml. The in vitro activity of sulopenem was unaffected by non-susceptibility to trimethoprim-sulfamethoxazole and/or ciprofloxacin, multidrug-resistant (MDR) phenotypes, extended-spectrum β-lactamases (ESBLs), or AmpC β-lactamases.