A role for keratin 17 during DNA damage response and tumor initiation.

High levels of the intermediate filament protein keratin 17 (K17) are associated with poor prognoses for several human carcinomas. Studies in mouse models have shown that K17 expression is positively associated with growth, survival, and inflammation in skin and that lack of K17 delays onset of tumorigenesis. K17 occurs in the nucleus of human and mouse tumor keratinocytes where it impacts chromatin architecture, gene expression, and cell proliferation. We report here that K17 is induced following DNA damage and promotes keratinocyte survival. The presence of nuclear K17 is required at an early stage of the double-stranded break (DSB) arm of the DNA damage and repair (DDR) cascade, consistent with its ability to associate with key DDR effectors, including γ-H2A.X, 53BP1, and DNA-PKcs. Mice lacking K17 or with attenuated K17 nuclear import showed curtailed initiation in a two-step skin carcinogenesis paradigm. The impact of nuclear-localized K17 on DDR and cell survival provides a basis for the link between K17 induction and poor clinical outcomes for several human carcinomas.

Major Bleeding After Paracentesis Associated With Apixaban Use: Two Case Reports.

We report 2 patients with compensated cirrhosis and moderate renal impairment who experienced severe bleeding complications from paracentesis during concurrent therapy with apixaban. While paracentesis has traditionally been considered a low bleeding-risk procedure and safe to perform without interruption of therapeutic anticoagulation, the increased concentrations observed in patients with impaired liver function may place these patients at unexpectedly high bleeding risk. Further investigation into the safety of paracentesis in patients with cirrhosis on apixaban may be warranted, as well as additional understanding of the clinical safety of this drug in Child-Pugh B cirrhosis.

Keratin 17 regulates nuclear morphology and chromatin organization.

Keratin 17 (KRT17; K17), a non-lamin intermediate filament protein, was recently found to occur in the nucleus. We report here on K17-dependent differences in nuclear morphology, chromatin organization, and cell proliferation. Human tumor keratinocyte cell lines lacking K17 exhibit flatter nuclei relative to normal. Re-expression of wild-type K17, but not a mutant form lacking an intact nuclear localization signal (NLS), rescues nuclear morphology in KRT17-null cells. Analyses of primary cultures of skin keratinocytes from a mouse strain expressing K17 with a mutated NLS corroborated these findings. Proteomics screens identified K17-interacting nuclear proteins with known roles in gene expression, chromatin organization and RNA processing. Key histone modifications and LAP2ß (an isoform encoded by TMPO) localization within the nucleus are altered in the absence of K17, correlating with decreased cell proliferation and suppression of GLI1 target genes. Nuclear K17 thus impacts nuclear morphology with an associated impact on chromatin organization, gene expression, and proliferation in epithelial cells.This article has an associated First Person interview with the first author of the paper.

Incidence and severity of thrombocytopenia associated with use of intravascular microaxial ventricular assist devices for treatment of cardiogenic shock.

INTRODUCTION: The use of temporary mechanical circulatory support (MCS) for patients with refractory cardiogenic shock has increased over the past decade. Impella devices (intravascular microaxial ventricular assist devices [VADs]) have become common MCS options but reportedly cause thrombocytopenia. Limited published data regarding the incidence or severity of microaxial VAD-associated thrombocytopenia exists. OBJECTIVES: The goal of this study was to determine the incidence, timing, and severity of thrombocytopenia in a microaxial VAD population. METHODS: A retrospective multicenter review of electronic medical records identified all patients implanted with microaxial VAD at three US academic teaching hospitals between June 2015 and August 2017. Patients were excluded for short-term procedural microaxial VAD use during percutaneous coronary intervention. RESULTS: Sixty-four patients underwent microaxial VAD insertion (95% for left-sided support) during the observed time period. Support was in place for a median duration of 5.2 (interquartile range [IQR]: 2.4-10.0) days. Within 7 days postinsertion, 98.5% of patients developed thrombocytopenia (platelet count <150,000/µl) and 81.3% of patients experienced a >50% platelet decrease. Average platelet count nadir was 68,200/µl or 63.9% from baseline occurring on median day 3.8 (IQR: 2.4-5.4). Twenty-four patients (38.1%) were tested for heparin-induced thrombocytopenia by the heparin-dependent antibody (HDA) test. All HDAs were either negative or had serotonin release assay negative confirmation. Postdevice removal, platelet counts returned to baseline or >150,000/µl in 63% of patients by Day 5. CONCLUSION: Microaxial VAD-associated thrombocytopenia is common. Practitioners should consider this when evaluating supported patients for other causes of thrombocytopenia. Platelet counts return to preimplantation levels within days of device removal.

Type I interferon-dependent CCL4 is induced by a cGAS/STING pathway that bypasses viral inhibition and protects infected tissue, independent of viral burden.

Type I interferons (T1-IFN) are critical in the innate immune response, acting upon infected and uninfected cells to initiate an antiviral state by expressing genes that inhibit multiple stages of the lifecycle of many viruses. T1-IFN triggers the production of Interferon-Stimulated Genes (ISGs), activating an antiviral program that reduces virus replication. The importance of the T1-IFN response is highlighted by the evolution of viral evasion strategies to inhibit the production or action of T1-IFN in virus-infected cells. T1-IFN is produced via activation of pathogen sensors within infected cells, a process that is targeted by virus-encoded immunomodulatory molecules. This is probably best exemplified by the prototypic poxvirus, Vaccinia virus (VACV), which uses at least 6 different mechanisms to completely block the production of T1-IFN within infected cells in vitro. Yet, mice lacking aspects of T1-IFN signaling are often more susceptible to infection with many viruses, including VACV, than wild-type mice. How can these opposing findings be rationalized? The cytosolic DNA sensor cGAS has been implicated in immunity to VACV, but has yet to be linked to the production of T1-IFN in response to VACV infection. Indeed, there are two VACV-encoded proteins that effectively prevent cGAS-mediated activation of T1-IFN. We find that the majority of VACV-infected cells in vivo do not produce T1-IFN, but that a small subset of VACV-infected cells in vivo utilize cGAS to sense VACV and produce T1-IFN to protect infected mice. The protective effect of T1-IFN is not mediated via ISG-mediated control of virus replication. Rather, T1-IFN drives increased expression of CCL4, which recruits inflammatory monocytes that constrain the VACV lesion in a virus replication-independent manner by limiting spread within the tissue. Our findings have broad implications in our understanding of pathogen detection and viral evasion in vivo, and highlight a novel immune strategy to protect infected tissue.

The Use of Cangrelor Infusions After Endovascular Aortic Repair With Prophylactic Lumbar Drain Placement.

Perioperative lumbar drains commonly are placed for spinal cord protection in patients undergoing endovascular aortic repair. However, the logistics of postoperative neuraxial drain removal is challenging in the presence of systemic antithrombotic therapy. This retrospective case series describes the novel use of cangrelor infusions in this high-risk setting. All lumbar drains were placed preoperatively, and descriptive data were collected including cangrelor infusion duration, time to lumbar drain removal after the infusion discontinuation, clinical course, and overall patient outcomes. There were no neurologic complications associated with lumbar drain insertion or removal, and median time to lumbar drain removal was 150 minutes after cangrelor infusion discontinuation. While further study is needed to validate its efficacy and safety, this case series highlights the promise of cangrelor infusions for systemic antithrombotic therapy in the cardiovascular/surgical intensive care unit.

Phosphorylation of serine 4,642 in the C-terminus of plectin by MNK2 and PKA modulates its interaction with intermediate filaments.

Plectin is a versatile cytolinker of the plakin family conferring cell resilience to mechanical stress in stratified epithelia and muscles. It acts as a critical organizer of the cytoskeletal system by tethering various intermediate filament (IF) networks through its C-terminal IF-binding domain (IFBD). Mutations affecting the IFBD cause devastating human diseases. Here, we show that serine 4642, which is located in the extreme C-terminus of plectin, is phosphorylated in different cell lines. Phosphorylation of S4642 decreased the ability of plectin IFBD to associate with various IFs, as assessed by immunofluorescence microscopy and cell fractionation studies, as well as in yeast two-hybrid assays. Plectin phosphorylated at S4642 was reduced at sites of IF network anchorage along cell-substrate contacts in both skin and cultured keratinocytes. Treatment of SK-MEL-2 and HeLa cells with okadaic acid increased plectin S4642 phosphorylation, suggesting that protein phosphatase 2A dephosphorylates this residue. Moreover, plectin S4642 phosphorylation was enhanced after cell treatment with EGF, phorbol ester, sorbitol and 8-bromo-cyclic AMP, as well as during wound healing and protease-mediated cell detachment. Using selective protein kinase inhibitors, we identified two different kinases that modulate the phosphorylation of plectin S4642 in HeLa cells: MNK2, which is downstream of the ERK1/2-dependent MAPK cascade, and PKA. Our study indicates that phosphorylation of S4642 has an important regulatory role in the interaction of plectin with IFs and identifies a novel link between MNK2 and the cytoskeleton.

Short-term use of an Impella ventricular assist device sterile water-based bicarbonate purge solution for positron emission tomography scanning.

DISCLAIMER: In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. PURPOSE: Impella microaxial ventricular assist devices require a dextrose-based purge solution in combination with heparin or sodium bicarbonate to prevent device dysfunction and stoppage, but the dextrose in these solutions can interfere with positron emission tomography (PET) scans, necessitating an alternative approach. SUMMARY: We describe the short-term use in 2 cases of an alternative purge solution for patients with an Impella 5.5 ventricular assist device undergoing PET scans to rule out infection and malignancy. Sodium chloride solutions cannot be used with Impella ventricular assist devices even for short periods of time due to the potential for motor corrosion. We therefore selected a sterile water-based sodium bicarbonate purge solution, incorporating a short dextrose-free period before and during the PET scan. Imaging was successfully performed with this alternative solution, with monitoring of Impella performance levels and purge parameters throughout the procedure indicating no adverse effects on pump function. CONCLUSION: Our sterile water-based purge solution coupled with short-term restriction of dextrose is a practical option for PET imaging in patients with a Pella ventricular assist device.

AIRE Deficiency Leads to the Development of Alopecia Areata‒Like Lesions in Mice.

Alopecia areata (AA) is an autoimmune hair loss disorder with no cure. Patients with sequence variation in AIRE are 15 times more likely to develop AA than the general population, yet the roles of AIRE in AA pathogenesis are unknown. In this study, we report that 62% of C57BL/6J female Aire‒/‒ mice spontaneously developed persistent AA-like lesions that displayed several hallmarks of human AA. Lesional Aire‒/‒ skin exhibited hair follicle (HF) dystrophy as determined by a reduced number of anagen HFs, decreased anagen HF proliferation, hair pigmentary changes, and decreased hair width and length. Inflammatory infiltrate comprising CD8+ T cells, CD4+ T cells, CD68+ macrophages, and mast cells was prominent in lesional Aire‒/‒ HFs. From gene expression analyses, we found lesional Aire‒/‒ skin to have significantly increased expression of human AA signature genes, including H2-Ab1, Ifnγ, IFN-γ‒induced chemokines (Ccl5, Cxcl9‒11), γc family cytokine receptor Il2RA, and JAK‒signal transducer and activator of transcription (STAT) signaling components (Stat1, Stat2, Stat4). By immunostaining, lesional Aire‒/‒ HFs also show upregulated major histocompatibility complex class I and downregulated α-melanocyte-stimulating hormone, signifying immune privilege collapse, and increased STAT1 activation in HF keratinocytes. Our study highlights a role for AIRE in HF biology and shows that Aire‒/‒ mice may serve as a valuable model system to study AA pathogenesis.

Propofol-induced interference with activated partial thromboplastin time-based monitoring of therapeutic heparin anticoagulation.

PURPOSE: The activated partial thromboplastin time (aPTT) is a coagulation assay commonly utilized for monitoring therapeutic heparin anticoagulation. aPTT methods based on optical detection are vulnerable to spectral interference from hemolysis, icterus, lipemia, and other substances. Intravenous lipid emulsions of primarily 20% have been shown to interfere with multiple clinical laboratory assays, including those measuring aPTT by optical methods, but there is limited data on propofol's effect. The primary objective of this study was to determine the rate of interference of propofol with aPTT measurements in patients receiving both propofol and intravenous heparin. METHODS: A retrospective observational cohort study of intensive care unit patients who received concomitant propofol and heparin infusions (N = 38 patients) and whose heparin therapy was monitored by aPTT (N = 531 aPTTs) was conducted. Review of the electronic medical record was completed to obtain relevant clinical and laboratory data, while the laboratory information system was queried for analytical interference with the aPTT assay. RESULTS: A total of 109 aPTTs (21%) spanning 21 patients (55%) had documented aPTT interference. All 21 patients had at least one aPTT requiring ultracentrifugation prior to reporting, and 12 aPTTs from 4 patients were unreportable due to interference. Patients with and without aPTT interference received similar doses of propofol. None of the cases of aPTT interference were caused by hemolysis or hyperbilirubinemia. CONCLUSION: A potential medication-assay interaction was observed in approximately half of patients who received concomitant propofol and heparin infusions and had aPTT measured for anticoagulation management. Sample ultracentrifugation removes the optical interference in most cases but significantly prolongs aPTT reporting and delays appropriate adjustments to heparin dosing.

Use of Sodium Bicarbonate Purge Solution in Impella Devices for Heparin-Induced Thrombocytopenia.

Heparin purge solution is recommended to be used in Impella devices to prevent biomaterial buildup and subsequent device dysfunction. The use of sodium bicarbonate purge solution in an Impella device is described in two patients with heparin-induced thrombocytopenia (HIT). The first case details a patient with severe mitral regurgitation and cardiogenic shock who had an Impella CP placed who developed HIT. Heparin purge solution was replaced by sodium bicarbonate purge solution in addition to systemic direct thrombin inhibitor (DTI) initiation. There was no significant change in Impella purge pressure or flow over the 13 days of Impella use. The second case describes a patient who developed an acute myocardial infarction and subsequent cardiogenic shock for which an Impella CP was placed who also developed HIT. Heparin purge solution was replaced by sodium bicarbonate purge solution. There was no significant change in purge pressure, flow, or motor current spikes over 11 days of use. In conclusion, we describe the successful use of a novel sodium bicarbonate purge solution utilized in patients with HIT for Impella management alone and in combination with systemic direct thrombin inhibitor therapy. This resulted in no protein deposition in the device gaps or device dysfunction.

AUTS2 Controls Neuronal Lineage Choice Through a Novel PRC1-Independent Complex and BMP Inhibition.

Despite a prominent risk factor for Neurodevelopmental disorders (NDD), it remains unclear how Autism Susceptibility Candidate 2 (AUTS2) controls the neurodevelopmental program. Our studies investigated the role of AUTS2 in neuronal differentiation and discovered that AUTS2, together with WDR68 and SKI, forms a novel protein complex (AWS) specifically in neuronal progenitors and promotes neuronal differentiation through inhibiting BMP signaling. Genomic and biochemical analyses demonstrated that the AWS complex achieves this effect by recruiting the CUL4 E3 ubiquitin ligase complex to mediate poly-ubiquitination and subsequent proteasomal degradation of phosphorylated SMAD1/5/9. Furthermore, using primary cortical neurons, we observed aberrant BMP signaling and dysregulated expression of neuronal genes upon manipulating the AWS complex, indicating that the AWS-CUL4-BMP axis plays a role in regulating neuronal lineage specification in vivo. Thus, our findings uncover a sophisticated cellular signaling network mobilized by a prominent NDD risk factor, presenting multiple potential therapeutic targets for NDD.

The calcium ATPase SERCA2 regulates desmoplakin dynamics and intercellular adhesive strength through modulation of PKCα signaling.

Darier's disease (DD) is an inherited autosomal-dominant skin disorder characterized histologically by loss of adhesion between keratinocytes. DD is typically caused by mutations in sarcoendoplasmic reticulum Ca(2+)-ATPase isoform 2 (SERCA2), a major regulator of intracellular Ca(2+) homeostasis in the skin. However, a defined role for SERCA2 in regulating intercellular adhesion remains poorly understood. We found that diminution of SERCA2 function by pharmacological inhibition or siRNA silencing in multiple human epidermal-derived cell lines was sufficient to disrupt desmosome assembly and weaken intercellular adhesive strength. Specifically, SERCA2-deficient cells exhibited up to a 60% reduction in border translocation of desmoplakin (DP), the desmosomal cytolinker protein necessary for intermediate filament (IF) anchorage to sites of robust cell-cell adhesion. In addition, loss of SERCA2 impaired the membrane translocation of protein kinase C α (PKCα), a known regulator of DP-IF association and desmosome assembly, to the plasma membrane by up to 70%. Exogenous activation of PKCα in SERCA2-deficient cells was sufficient to rescue the defective DP localization, desmosome assembly, and intercellular adhesive strength to levels comparable to controls. Our findings indicate that SERCA2-deficiency is sufficient to impede desmosome assembly and weaken intercellular adhesive strength via a PKCα-dependent mechanism, implicating SERCA2 as a novel regulator of PKCα signaling.

Robust, Durable Gene Activation In Vivo via mRNA-Encoded Activators.

Programmable control of gene expression via nuclease-null Cas9 fusion proteins has enabled the engineering of cellular behaviors. Here, both transcriptional and epigenetic gene activation via synthetic mRNA and lipid nanoparticle delivery was demonstrated in vivo. These highly efficient delivery strategies resulted in high levels of activation in multiple tissues. Finally, we demonstrate durable gene activation in vivo via transient delivery of a single dose of a gene activator that combines VP64, p65, and HSF1 with a SWI/SNF chromatin remodeling complex component SS18, representing an important step toward gene-activation-based therapeutics. This induced sustained gene activation could be inhibited via mRNA-encoded AcrIIA4, further improving the safety profile of this approach.

Nebulized mRNA-Encoded Antibodies Protect Hamsters from SARS-CoV-2 Infection.

Despite the success of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccines, there remains a clear need for new classes of preventatives for respiratory viral infections due to vaccine hesitancy, lack of sterilizing immunity, and for at-risk patient populations, including the immunocompromised. While many neutralizing antibodies have been identified, and several approved, to treat COVID-19, systemic delivery, large doses, and high costs have the potential to limit their widespread use, especially in low- and middle-income countries. To use these antibodies more efficiently, an inhalable formulation is developed that allows for the expression of mRNA-encoded, membrane-anchored neutralizing antibodies in the lung to mitigate SARS-CoV-2 infections. First, the ability of mRNA-encoded, membrane-anchored, anti-SARS-CoV-2 antibodies to prevent infections in vitro is demonstrated. Next, it is demonstrated that nebulizer-based delivery of these mRNA-expressed neutralizing antibodies potently abrogates disease in the hamster model. Overall, these results support the use of nebulizer-based mRNA expression of neutralizing antibodies as a new paradigm for mitigating respiratory virus infections.

DOT1L modulates the senescence-associated secretory phenotype through epigenetic regulation of IL1A.

Oncogene-induced senescence (OIS) is a stable cell cycle arrest that occurs in normal cells upon oncogene activation. Cells undergoing OIS express a wide variety of secreted factors that affect the senescent microenvironment termed the senescence-associated secretory phenotype (SASP), which is beneficial or detrimental in a context-dependent manner. OIS cells are also characterized by marked epigenetic changes. We globally assessed histone modifications of OIS cells and discovered an increase in the active histone marks H3K79me2/3. The H3K79 methyltransferase disruptor of telomeric silencing 1-like (DOT1L) was necessary and sufficient for increased H3K79me2/3 occupancy at the IL1A gene locus, but not other SASP genes, and was downstream of STING. Modulating DOT1L expression did not affect the cell cycle arrest. Together, our studies establish DOT1L as an epigenetic regulator of the SASP, whose expression is uncoupled from the senescence-associated cell cycle arrest, providing a potential strategy to inhibit the negative side effects of senescence while maintaining the beneficial inhibition of proliferation.

Sam68 is required for the growth and survival of nonmelanoma skin cancer.

Although targeting DNA repair signaling pathways has emerged as a promising therapeutic for skin cancer, the relevance of DNA damage responses (DDR) in the development and survival of nonmelanoma skin cancer (NMSC), the most common type of skin cancer, remains obscure. Here, we report that Src-associated substrate during mitosis of 68 kDa (Sam68), an early signaling molecule in DDR, is elevated in skin tumor tissues derived from NMSC patients and skin lesions from Gli2-transgenic mice. Downregulation of Sam68 impacts the growth and survival of human tumor keratinocytes and genetic ablation of Sam68 delays the onset of basal cell carcinomas (BCC) in Gli2-transgenic mice. Moreover, Sam68 plays a critical role in DNA damage-induced DNA repair and nuclear factor kappa B (NF-κB) signaling pathways in keratinocytes, hence conferring keratinocyte sensitivity to DNA damaging agents. Together, our data reveal a novel function of Sam68 in regulating DDR in keratinocytes that is crucial for the growth and survival of NMSC.