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Abstract
Adult renal proximal tubules are composed of terminally differentiated epithelial cells that exhibit few signs of proliferation over time. However, upon acute kidney injury (AKI), surviving epithelial cells can re-enter the mitotic cycle and express genes and proteins coincident with a dedifferentiated, more embryonic phenotype. While a stable, terminally differentiated cellular phenotype is thought to be maintained, at least in part, by epigenetic imprints that impart both active and repressive histone marks, it is unclear whether regenerating cells after injury need to replicate such marks to recover. To test whether renal epithelial cell regeneration is dependent on histone H3K4 methylation, we generated a mouse model that deleted the Paxip1 gene in mature renal proximal tubules. Paxip1 encodes the adaptor protein PTIP, which is part of an Mll3/4 histone H3K4 methyltransferase complex and is essential for embryonic development. Mice with PTIP deletions in the adult kidney proximal tubules were viable and fertile. Upon acute kidney injury, such mice failed to regenerate damaged tubules leading to scarring and interstitial fibrosis. The inability to repair damage was likely due to a failure to re-enter mitosis and reactivate regulatory genes such as Sox9, which is necessary for epithelial cell regeneration. PTIP deletion reduced histone H3K4 methylation in uninjured adult kidneys but did not significantly affect function or the expression of epithelial specific markers. A transient decrease in trimethylation was also observed in controls after AKI but returned to normal after repair. Strikingly, cell lineage tracing revealed that surviving PTIP mutant cells could alter their phenotype and lose epithelial markers. These data demonstrate that PTIP and associated MLL3/4 mediated histone methylation are needed for regenerating proximal tubules and to maintain or reestablish the cellular epithelial phenotype.
Authors
Abdul Soofi, Ana P. Kutschat, Mohammad H. Azam, Ann M. Laszczyk, Gregory R. Dressler
Abstract
Dengue (DENV) and Zika viruses (ZIKV) are closely related mosquito-borne flaviviruses that co-circulate in tropical regions and constitute major threats to global human health. Whether preexisting immunity to one virus affects disease caused by the other during primary or secondary infections is unknown but is critical in preparing for future outbreaks and predicting vaccine safety. Using a human skin explant model, we show that DENV-3 immune sera increased recruitment and infection of Langerhans cells, macrophages and dermal dendritic cells following inoculation with DENV-2 or ZIKV. Similarly, ZIKV immune sera enhanced infection with DENV-2. Immune sera increased migration of infected Langerhans cells to dermis and emigration of infected cells out of skin. Heterotypic immune sera increased viral RNA in dermis almost tenfold and reduced the amount of virus required to infect a majority of myeloid cells by 100 to 1,000 fold. Enhancement was associated with cross-reactive IgG and induction of IL-10 expression and was mediated by both CD32 and CD64 Fcγ receptors. These findings reveal that preexisting heterotypic immunity greatly enhances DENV and ZIKV infection, replication and spread in human skin. This relevant tissue model will be valuable in assessing the efficacy and risk of dengue and Zika vaccines in humans.
Authors
Priscila M.S. Castanha, Geza Erdos, Simon C. Watkins, Louis D. Falo, Jr., Ernesto T.A. Marques, Simon M. Barratt-Boyes
Abstract
BACKGROUND. The circadian system entrains behavioral and physiological rhythms to environmental cycles and modern lifestyles disrupt this entrainment. We investigated a timed exercise intervention to phase shift the internal circadian rhythm. METHODS. In fifty-two young, sedentary adults, dim light melatonin onset (DLMO) was measured before and after five days of morning (10h after DLMO; n = 26) or evening (20h after DLMO; n = 26) exercise. Phase shifts were calculated as the difference in DLMO before and after exercise. RESULTS. Morning exercise induced phase advance shifts (0.62 ± 0.18h) that were significantly greater than phase shifts from evening exercise (-0.02 ± 0.18h; P = 0.01). Chronotype also influenced the effect of timed exercise. For later chronotypes, both morning and evening exercise induced phase advances (0.54 ± 0.29h and 0.46 ±0.25h, respectively). In contrast, earlier chronotypes had phase advances from morning exercise (0.49 ± 0.25h), but phase delays from evening exercise (-0.41 ± 0.29h). CONCLUSION. Late chronotypes, who experience the most severe circadian misalignment, may benefit from phase advances induced by exercise in the morning or evening, but evening exercise may exacerbate circadian misalignment in early chronotypes. Thus, personalized exercise timing prescription based on chronotype could alleviate circadian misalignment in young adults. TRIAL REGISTRATION. www.clinicaltrials.gov, NCT # NCT04097886.FUNDING. National Institutes of Health grants UL1TR001998 and TL1TR001997, the Barnstable Brown Diabetes and Obesity Center, the Pediatric Exercise Physiology Laboratory Endowment, the Arvle and Ellen Turner Thacker Research Fund, and the University of Kentucky.
Authors
J. Matthew Thomas, Philip A. Kern, Heather M. Bush, Kristen J. McQuerry, W. Scott Black, Jody L. Clasey, Julie S. Pendergast
Abstract
BACKGROUND. Mitochondrial dysfunction, a proposed mechanism of COPD pathogenesis, is associated with the leakage of mitochondrial DNA (mtDNA), which may be detected extracellularly in various bodily fluids. Despite evidence for the increased prevalence of chronic kidney disease in COPD subjects and for mitochondrial dysfunction in the kidneys of murine COPD models, whether urine mtDNA (u-mtDNA) associates with measures of disease severity in COPD is unknown. METHODS. Cell-free u-mtDNA, defined as copy number of mitochondrially-encoded NADH dehydrogenase-1 (MTND1) gene, was measured by real-time quantitative PCR and normalized to urine creatinine in cell-free urine samples from participants in the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) cohort. Urine albumin/creatinine ratios (UACR) were measured in the same samples. Associations between u-mtDNA and UACR and clinical disease parameters, including FEV1 % predicted, clinical measures of exercise tolerance, respiratory symptom burden, and chest CT measures of lung structure were examined. RESULTS. U-mtDNA and UACR levels were measured in never smokers (n = 64), smokers without airflow obstruction (n = 109), participants with mild/moderate COPD (n = 142), and participants with severe COPD (n = 168). U-mtDNA was associated with increased respiratory symptom burden, especially among smokers without COPD. Significant sex differences in u-mtDNA levels were observed with females having higher u-mtDNA levels across all study subgroups. U-mtDNA associated with worse spirometry and CT emphysema in males only, and worse respiratory symptoms in females only. Similar associations were not found with UACR. CONCLUSION. U-mtDNA levels may help to identify distinct clinical phenotypes and underlying pathobiological differences in males versus females with COPD.
Authors
William Z. Zhang, Michelle C. Rice, Katherine L. Hoffman, Clara Oromendia, Igor Barjaktarevic, J. Michael Wells, Annette T. Hastie, Wassim W. Labaki, Christopher B. Cooper, Alejandro P. Comellas, Gerard J. Criner, Jerry A. Krishnan, Robert Paine III, Nadia N. Hansel, Russell P. Bowler, R. Graham Barr, Stephen P. Peters, Prescott G. Woodruff, Jeffrey L. Curtis, Meilan K. Han, Karla V. Ballman, Fernando J. Martinez, Augustine M.K. Choi, Kiichi Nakahira, Suzanne M. Cloonan, Mary E. Choi
Abstract
Ultrasound-induced microbubble (USMB) cavitation is widely used to promote drug delivery. Our previous study investigated USMB targeting round window membrane by applying the ultrasound transducer to tympanic bulla. In the present study we further extended the use of this technology to enhance drug delivery to inner ear by introducing the ultrasound transducer into external auditory canal (EAC) or applying it to skull. Using a three-dimensional-printed diffusion apparatus mimicking the pathway for ultrasound passing through and reaching middle ear cavity in vitro, both models simulating the transcanal and transcranial approach demonstrated 4.8-fold and 3.7-fold higher delivery efficiencies, respectively. In vivo model of guinea pigs, by filling tympanic bulla with microbubbles and biotin-fluorescein (biotin-FITC), USMB applied transcanally and transcranially induced 2.8-fold and 1.5-fold increases in biotin-FITC delivery efficiencies, respectively. In addition, the gentamicin uptake by cochlear and vestibular hair cells and gentamicin-induced hair cell loss were significantly enhanced following transcanal application of USMB. On the 28th day after transcanal USMB, safety assessment showed no significant changes in the hearing thresholds and the integrity of cochlea. These are the first results to demonstrate the feasibility and support the potential clinical application of applying USMB via EAC to facilitate drug delivery into inner ear.
Authors
Ai-Ho Liao, Chih-Hung Wang, Ping-Yu Weng, Yi-Chun Lin, Hao Wang, Hang-Kang Chen, Hao-Li Liu, Ho-Chiao Chuang, Cheng-Ping Shih
Abstract
To investigate the nationwide severe fever with thrombocytopenia syndrome virus (SFTSV) infection status, we isolated SFTSVs from severe fever with thrombocytopenia syndrome (SFTS)-suspected patients in 207 hospitals throughout South Korea between 2013 and April of 2017. A total of 116 SFTSVs were isolated from 3,137 SFTS-suspected patients with an overall 21.6% case fatality rate. Genetic characterization revealed that at least six genotypes of SFTSVs are co-circulating in South Korea with multiple reassortments among them. Of these, the genotype B-2 strains were the most prevalent (n = 48, 36.1%) followed by the A and F genotypes. Clinical and epidemiologic investigations revealed that genotype B strains were associated with the highest case-fatality rate (34.8%, 32/92), while genotype A caused only one fatality out of ten patients. Further, ferret infection studies demonstrated varied clinical manifestations and case mortality rates of different strains of SFTSV, which suggests this virus could exhibit genotype-dependent pathogenicity.Keywords: severe fever with thrombocytopenia syndrome virus (SFTSV), clinical manifestations, genotypes, pathogenesis
Authors
Seok-Min Yun, Su-Jin Park, Young-Il Kim, Sun-Whan Park, Min-Ah Yu, Hyeok-Il Kwon, Eun-Ha Kim, Kwang-Min Yu, Hye Won Jeong, Jungsang Ryou, Won-Ja Lee, Youngmee Jee, Joo-Yeon Lee, Young Ki Choi
Abstract
Mutations in cardiac myosin binding protein (MyBP-C, encoded by MYBPC3) are the most common cause of hypertrophic cardiomyopathy (HCM). Most MYBPC3 mutations result in premature termination codons (PTCs) that cause RNA degradation and a reduction of MyBP-C in HCM patient hearts. However, a reduction in MyBP-C has not been consistently observed in MYBPC3 mutant induced pluripotent stell cell cardiomyocytes (iPSCMs). To determine early MYBPC3 mutation effects, we utilized both patient and genome-engineered iPSCMs. iPSCMs with frameshift mutations were compared to iPSCMs with MYBPC3 promoter and translational start site deletions, revealing that allelic loss of function is the primary inciting consequence of mutations that cause PTCs. Despite a reduction in wild type mRNA in all heterozygous iPSCMs, no reduction in MyBP-C protein was observed, indicating protein-level compensation through a previously uncharacterized mechanism. Although homozygous mutant iPSCMs exhibited contractile dysregulation, heterozygous mutant iPSCMs had normal contractile function in the context of compensated MyBP-C levels. Agnostic RNA-seq analysis revealed differential expression in protein chaperone genes as the only dysregulated gene set. To determine how MYBPC3 mutant iPSCMs achieve compensated MyBP-C levels, sarcomeric protein synthesis and degradation were measured with stable isotope-labeling. Heterozygous mutant iPSCMs showed reduced MyBP-C synthesis rates but with a corresponding reduction in MyBP-C degradation. These findings indicate that cardiomyocytes have an innate capacity to attain normal MyBP-C stoichiometry despite MYBPC3 allelic loss of function due to truncating mutations. Modulating MyBP-C degradation to maintain MyBP-C protein levels may be a novel treatment approach upstream of contractile dysfunction for HCM patients.
Authors
Adam S Helms, Vi T. Tang, Thomas S. O'Leary, Sabrina Friedline, Mick Wauchope, Akul Arora, Aaron H Wasserman, Eric D Smith, Lap Man Lee, Xiaoquan Wen, Jordan A. Shavit, Allen P Liu, Michael J Previs, Sharlene M. Day
Abstract
Genetic variants within/near the interferon regulatory factor 5 (IRF5) locus associate with systemic lupus erythematosus (SLE) across ancestral groups. The major IRF5-SLE risk haplotype is common across populations, yet immune functions for the risk haplotype are undefined. We characterized the global immune-phenotype of healthy donors homozygous for the major risk and non-risk haplotypes and identified cell lineage-specific alterations that mimic pre-symptomatic SLE. Contrary to previous studies in B lymphoblastoid cell lines and SLE immune cells, IRF5 genetic variants had little effect on IRF5 protein levels in healthy donors. Instead, we detected basal IRF5 hyper-activation in the myeloid compartment of risk donors that drives the SLE immune-phenotype. Risk donors were ANA positive with anti-Ro and -MPO specificity, had increased circulating plasma cells and plasmacytoid dendritic cells, and enhanced spontaneous NETosis. The IRF5-SLE immune-phenotype was conserved over time and probed mechanistically by ex vivo co-culture, indicating that risk neutrophils are drivers of the global immune-phenotype. RNA-seq of risk neutrophils revealed increased IRF5 transcript expression, IFN pathway enrichment and decreased expression of ROS pathway genes. Altogether, data support that individuals carrying the IRF5-SLE risk haplotype are more susceptible to environmental/stochastic influences that trigger chronic immune activation, predisposing to the development of clinical SLE.
Authors
Dan Li, Bharati Matta, Su Song, Victoria Nelson, Kirsten Diggins, Kim R. Simpfendorfer, Peter K. Gregersen, Peter Linsley, Betsy J. Barnes
Abstract
The ciliopathies Bardet-Biedl Syndrome and Alström Syndrome are genetically inherited pleiotropic disorders with primary clinical features of hyperphagia and obesity. Methionine aminopeptidase 2 inhibitors (MetAP2i) have been shown in preclinical and clinical studies to reduce food intake, body weight, and adiposity. Here we investigated the effects of MetAP2i administration in a mouse model of ciliopathy produced by conditional deletion of the Thm1 gene in adulthood. Thm1 conditional knock-out (cko) mice show decreased hypothalamic pro-opiomelanocortin expression as well as hyperphagia, obesity, metabolic disease and hepatic steatosis. In obese Thm1 cko mice, two-week administration of MetAP2i reduced daily food intake and reduced body weight 17.1% from baseline (vs. 5% reduction for vehicle). This was accompanied with decreased levels of blood glucose, insulin and leptin. Further, MetAP2i reduced gonadal adipose depots and adipocyte size and improved liver morphology. This is the first report of MetAP2i reducing hyperphagia and body weight, and ameliorating metabolic indices in a mouse model of ciliopathy. These results support further investigation of MetAP2 inhibition as a potential therapeutic strategy for ciliary-mediated forms of obesity.
Authors
Tana S Pottorf, Micaella P. Fagan, Bryan F. Burkey, David J Cho, James E Vath, Pamela V. Tran
Abstract
A recent study of AHSCT for active relapsing-remitting multiple sclerosis (RRMS) showed efficacy in preventing disease worsening. However, the immunologic basis for efficacy remains poorly defined. MS pathology is known to be driven by inflammatory T cells that infiltrate the central nervous system (CNS). Therefore, we hypothesized that the pre-existing T cell repertoire in the intrathecal compartment of active RRMS participants was ablated, and replaced with new clones following AHSCT. T cell repertoires were assessed using high-throughput TCRβ chain sequencing in paired cerebrospinal fluid (CSF) and peripheral blood CD4+ and CD8+ T cells from participants that underwent AHSCT, before and up to 4 years following transplantation. >90% of the pre-existing CSF repertoire in participants with active RRMS was removed following AHSCT, and replaced with clonotypes predominantly generated from engrafted autologous stem cells. Of the pre-existing clones in CSF, ~60% were also detected in pre-therapy blood, and concordant treatment effects were observed for clonotypes in both compartments following AHSCT. These results indicate that replacement of the pre-existing TCR repertoire in active RRMS is a mechanism for AHSCT efficacy, and suggest that peripheral blood could serve as a surrogate for CSF to define mechanisms associated with efficacy in future studies of AHSCT.
Authors
Kristina M. Harris, Noha Lim, Paul Lindau, Harlan Robins, Linda M. Griffith, Richard A. Nash, Laurence A. Turka, Paolo A. Muraro
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