Faculty Bibliography

Inflammatory Bowel Disease (IBD) is an autoimmune condition with complicated pathology and diverse clinical signs. TNFα is believed to play a crucial role in the pathogenesis of IBD. We recently identified fexofenadine, a well-known antagonist of histamine H1 receptor, as a novel inhibitor of TNFα signaling. Additionally, cytosolic phospholipase A2 (cPLA2) was isolated as a binding target of fexofenadine, and fexofenadine-mediated anti-TNF activity relied on cPLA2 in vitro. The objective of this study is to determine whether fexofenadine is therapeutic against chemically-induced murine IBD model and whether cPLA2 and/or histamine H1 receptor is important for fexofenadine's anti-inflammatory activity in vivo by leveraging various genetically modified mice and chemically induced murine IBD models. Both dextran sulfate sodium- and 2, 4, 6-trinitrobenzene sulfonic acid-induced murine IBD models revealed that orally delivered fexofenadine was therapeutic against IBD, evidenced by mitigated clinical symptoms, decreased secretions of the proinflammatory cytokine IL-6 and IL-1β, lowered intestinal inflammation, and reduced p-p65 and p-IĸBα. Intriguingly, Fexofenadine-mediated protective effects against IBD were lost in cPLA2 deficient mice but not in histamine H1 receptor-deficient mice. Collectively, these findings demonstrate the therapeutic effects of over-the-counter drug Fexofenadine in treating DSS-induced IBD murine and provide first in vivo evidence showing that cPLA2 is required for fexofenadine's therapeutic effects in murine IBD model and probably other inflammatory and autoimmune diseases as well.

Gpr125, encoded by Adgra3, is an orphan adhesion G-protein coupled receptor (aGPCR) implicated in modulating Wnt signaling and planar polarity. Here we establish both physiological and pathological roles for Gpr125. We show that mice lacking Gpr125 or its signaling domains display an ocular phenotype with many hallmarks of human dry eye syndrome. These include squinting, abnormal lacrimation, mucus accumulation, swollen eyelids and inflammatory infiltration of lacrimal and meibomian glands. Utilizing a Gpr125-β-gal reporter and scRNAseq, we identify Gpr125 expression in a discrete population of cells located at the tips of migrating embryonic lacrimal ducts. By lineage tracing we show these cells function as progenitors of the adult lacrimal myoepithelium. Beyond defining an essential role for Gpr125 in tear film and identifying its utility as a marker of lacrimal progenitors, this study implicates Gpr125 in the etiology of blepharitis and dry eye syndrome, and defines novel animal models of these common maladies

PIWI proteins and their guiding Piwi-interacting small RNAs (piRNAs) are crucial for fertility and transposon defense in the animal germline. In most species, the majority of piRNAs are produced from distinct large genomic loci, called piRNA clusters. It is assumed that germline-expressed piRNA clusters, particularly in Drosophila, act as principal regulators to control transposons dispersed across the genome. Here, using synteny analysis, we show that large clusters are evolutionarily labile, arise at loci characterized by recurrent chromosomal rearrangements, and are mostly species-specific across the Drosophila genus. By engineering chromosomal deletions in D. melanogaster, we demonstrate that the three largest germline clusters, which account for the accumulation of >40% of all transposon-targeting piRNAs in ovaries, are neither required for fertility nor for transposon regulation in trans. We provide further evidence that dispersed elements, rather than the regulatory action of large Drosophila germline clusters in trans, may be central for transposon defense.

PERK is an endoplasmic reticulum (ER) transmembrane sensor that phosphorylates eIF2α to initiate the Unfolded Protein Response (UPR). eIF2α phosphorylation promotes stress-responsive gene expression most notably through the transcription factor ATF4 that contains a regulatory 5' leader. Possible PERK effectors other than ATF4 remain poorly understood. Here, we report that the bZIP transcription factor Xrp1 is required for ATF4-independent PERK signaling. Cell-type-specific gene expression profiling in Drosophila indicated that delta-family glutathione-S-transferases (gstD) are prominently induced by the UPR-activating transgene Rh1^G69D. Perk was necessary and sufficient for such gstD induction, but ATF4 was not required. Instead, Perk and other regulators of eIF2α phosphorylation regulated Xrp1 protein levels to induce gstDs. The Xrp1 5' leader has a conserved upstream Open Reading Frame (uORF) analogous to those that regulate ATF4 translation. The gstD-GFP reporter induction required putative Xrp1 binding sites. These results indicate that antioxidant genes are highly induced by a previously unrecognized UPR signaling axis consisting of PERK and Xrp1.

Zebrafish provide an excellent model for in vivo cell biology studies because of their amenability to live imaging. Protein visualization in zebrafish has traditionally relied on overexpression of fluorescently tagged proteins from heterologous promoters, making it difficult to recapitulate endogenous expression patterns and protein function. One way to circumvent this problem is to tag the proteins by modifying their endogenous genomic loci. Such an approach is not widely available to zebrafish researchers because of inefficient homologous recombination and the error-prone nature of targeted integration in zebrafish. Here, we report a simple approach for tagging proteins in zebrafish on their N or C termini with fluorescent proteins by inserting PCR-generated donor amplicons into non-coding regions of the corresponding genes. Using this approach, we generated endogenously tagged alleles for several genes that are crucial for epithelial biology and organ development, including the tight junction components ZO-1 and Cldn15la, the trafficking effector Rab11a, the apical polarity protein aPKC and the ECM receptor Integrin β1b. Our approach facilitates the generation of knock-in lines in zebrafish, opening the way for accurate quantitative imaging studies.

BACKGROUND:Staged implant-based breast reconstruction is the most common reconstructive modality following mastectomy. Postoperative implant infections can have a significant impact on adjuvant oncologic care and reconstructive outcome. Here, we investigate the impact of β-lactam antibiotics (i.e., bactericidal) compared to alternative antibiotic agents on postoperative outcomes for implant-based breast reconstruction. METHODS:A retrospective analysis of patients who underwent immediate sub-pectoral tissue expander placement with an inferior acellular dermal matrix (ADM) sling at a single institution between May 2008 and July 2018 was performed. Patient demographics, comorbidities, and complication rates were retrieved. The impact of antibiotic regimen on postoperative outcomes, including infection rate and reconstructive failure, was investigated. RESULTS:, respectively, who underwent 542 immediate breast reconstructions were included in the study. The use of a β-lactam antibiotic was protective against postoperative infection (odds ratio [OR] = 0.467, p = .046), infection requiring operative management (OR = 0.313, p = .022), and reconstructive failure (OR = 0.365, p = .028). Extended, that is, post-discharge, prophylaxis was not associated with any clinical benefit. CONCLUSION/CONCLUSIONS:The use of β-lactam antibiotics for pre-/peri-operative prophylaxis is superior to alternative antibiotics with a bacteriostatic mechanism of action regarding rates of postoperative infection and reconstructive failure following immediate tissue expander-based breast reconstruction. Extended, that is, post-discharge, prophylaxis does not appear to be indicated, regardless of the antibiotic chosen.

BACKGROUND:The purpose of this study is to describe a Level 1 Trauma Center's orthopedic response to the COVID-19 pandemic, and to compare outcomes of acute fracture patients pre-COVID versus during the COVID-19 pandemic. METHODS:All inpatient fracture cases performed over a 5-month period were identified and retrospective chart review performed. Patients were divided into pre- and COVID-era groups based on when surgery was performed relative to March 16, 2020 (the date elective operations were ceased), and groups were statistically compared. Patients with a COVID test result were further sub-divided into COVID negative and positive groups, and statistically compared. Statistical analysis was performed using independent t-test for continuous variables and chi-square analysis for categorical variables. RESULTS:One hundred and nineteen patients were identified, 38% females with average age of 58 years. Average length of stay was 7 days with average time from injury to surgery of 3 days and average time from admission to surgery of 1.3 days. Overall in-hospital complication rate was 29.4%, and 30-day mortality and readmission rates were 2.5% and 5%, respectively. Sixty-nine patients comprised the pre-COVID group, and 50 in the COVID-era group. There was no significant difference with respect to length of stay, time from injury to surgery, time from admission to surgery, need for post-operative ICU stay, in-hospital complication rate, 30-day mortality rate and 30-day readmission rate. Thirty-four patients had COVID testing, with 24 negative and 10 positive. COVID-positive patients had longer time from injury to surgery (8.5 days vs. 2 days, p = 0.003) and longer time from admission to surgery (2.7 days vs. 1.2 days, p = 0.034). While more COVID-positive patients required ICU admission post-operatively (60% vs. 21%, p = 0.036), there was no difference in overall complication rate. CONCLUSIONS:Orthopedic care of acute fracture patients was not affected by a global pandemic. The response of our Level 1 Trauma Center's orthopedic department can guide other hospitals if and when new surges in COVID cases arise, in order to prevent compromising appropriate orthopedic care. LEVEL OF EVIDENCE/METHODS:Prognostic III.

Arrhythmogenic cardiomyopathy (ACM) is a familial disease, with approximately 60% of patients displaying a pathogenic variant. The majority of genes linked to ACM code for components of the desmosomes: plakophilin-2 (PKP2), desmoglein-2 (DSG2) and desmocollin-2 (DSC2), plakoglobin (JUP) and desmoplakin (DSP). Genetic variants involving the desmosomes are known to cause dysfunction of cell-to-cell adhesions and intercellular gap junctions. In turn, this may result in failure to mechanically hold together the cardiomyocytes, fibrofatty myocardial replacement, cardiac conduction delay and ventricular arrhythmias. It is becoming clearer that pathogenic variants in desmosomal genes such as PKP2 are not only responsible for a mechanical dysfunction of the intercalated disc (ID), but are also the cause of various pro-arrhythmic mechanisms. In this review, we discuss in detail the different molecular interactions associated with desmosomal pathogenic variants, and their contribution to various ACM phenotypes.