Browsing by Author "Karns, Rebekah"

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    Association of Baseline Luminal Narrowing With Ileal Microbial Shifts and Gene Expression Programs and Subsequent Transmural Healing in Pediatric Crohn Disease
    (Oxford University Press, 2021) Ta, Allison D.; Ollberding, Nicholas J.; Karns, Rebekah; Haberman, Yael; Alazraki, Adina L.; Hercules, David; Baldassano, Robert; Markowitz, James; Heyman, Melvin B.; Kim, Sandra; Kirschner, Barbara; Shapiro, Jason M.; Noe, Joshua; Oliva-Hemker, Maria; Otley, Anthony; Pfefferkorn, Marian; Kellermayer, Richard; Snapper, Scott; Rabizadeh, Shervin; Xavier, Ramnik; Dubinsky, Marla; Hyams, Jeffrey; Kugathasan, Subra; Jegga, Anil G.; Dillman, Jonathan R.; Denson, Lee A.; Pediatrics, School of Medicine
    Background: Transmural healing (TH) is associated with better long-term outcomes in Crohn disease (CD), whereas pretreatment ileal gene signatures encoding myeloid inflammatory responses and extracellular matrix production are associated with stricturing. We aimed to develop a predictive model for ileal TH and to identify ileal genes and microbes associated with baseline luminal narrowing (LN), a precursor to strictures. Materials and methods: Baseline small bowel imaging obtained in the RISK pediatric CD cohort study was graded for LN. Ileal gene expression was determined by RNASeq, and the ileal microbial community composition was characterized using 16S rRNA amplicon sequencing. Clinical, demographic, radiologic, and genomic variables were tested for association with baseline LN and future TH. Results: After controlling for ileal location, baseline ileal LN (odds ratio [OR], 0.3; 95% confidence interval [CI], 0.1-0.8), increasing serum albumin (OR, 4; 95% CI, 1.3-12.3), and anti-Saccharomyces cerevisiae antibodies IgG serology (OR, 0.97; 95% CI, 0.95-1) were associated with subsequent TH. A multivariable regression model including these factors had excellent discriminant power for TH (area under the curve, 0.86; positive predictive value, 80%; negative predictive value, 87%). Patients with baseline LN exhibited increased Enterobacteriaceae and inflammatory and extracellular matrix gene signatures, coupled with reduced levels of butyrate-producing commensals and a respiratory electron transport gene signature. Taxa including Lachnospiraceae and the genus Roseburia were associated with increased respiratory and decreased inflammatory gene signatures, and Aggregatibacter and Blautia bacteria were associated with reduced extracellular matrix gene expression. Conclusions: Pediatric patients with CD with LN at diagnosis are less likely to achieve TH. The association between specific microbiota, wound healing gene programs, and LN may suggest future therapeutic targets.
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    Comparative Analysis of Global Hepatic Gene Expression in Adolescents and Adults with Non-alcoholic Fatty Liver Disease
    (Fortune Journals, 2023) Gawrieh, Samer; Karns, Rebekah; Kleiner, David E.; Olivier, Michael; Jenkins, Todd; Inge, Thomas H.; Chalasani, Naga P.; Xanthakos, Stavra; Medicine, School of Medicine
    Introduction: To gain insights into the mechanisms underlying distinct nonalcoholic fatty liver disease (NAFLD) histological phenotypes between children and adults, we compared hepatic gene expression profiles associated with NAFLD phenotypes between the two age groups. Methods: Histological characteristics of intra-operative liver biopsies from adolescents and adults undergoing bariatric surgery were assessed by the same pathologist using the non-alcoholic steatohepatitis (NASH) Clinical Research Network scoring system. Hepatic gene expression was measured by microarray analysis. Transcriptomic signatures of histological phenotypes between the two groups were compared, with significance defined as p-value <0.05 and a fold change >1.5. Results: In 67 adolescents and 76 adults, distribution of histological phenotypes was: not-NAFLD (controls) 51% vs 39%, NAFL 39% vs 37%, and NASH 10% vs 24%, respectively. There were 279 differentially expressed genes in adolescents and 213 in adults with NAFLD vs controls. In adolescents, transcriptomes for NAFL vs controls, and borderline vs definite NASH were undifferentiable, whereas in adults, NAFL and borderline NASH demonstrated a transcriptomic gradient between controls and definite NASH. When applied to adolescents, significant adult genes discriminated borderline and definite NASH from control and NAFL, but the majority of significant pediatric genes were not portable to adults. Genes associated with NASH in adolescents and adults showed some ontological consistency but notable differences. Conclusions: There is some similarity but major differences in the transcriptomic profiles associated with NAFLD between adolescents and adults with severe obesity. These data suggest different mechanisms contribute to the pathogenesis of NAFLD severity at different stages in life.
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    Stratification of risk of progression to colectomy in ulcerative colitis via measured and predicted gene expression
    (Elsevier, 2021) Mo, Angela; Nagpal, Sini; Gettler, Kyle; Haritunians, Talin; Giri, Mamta; Haberman, Yael; Karns, Rebekah; Prince, Jarod; Arafat, Dalia; Hsu, Nai-Yun; Chuang, Ling-Shiang; Argmann, Carmen; Kasarskis, Andrew; Suarez-Farinas, Mayte; Gotman, Nathan; Mengesha, Emebet; Venkateswaran, Suresh; Rufo, Paul A.; Baker, Susan S.; Sauer, Cary G.; Markowitz, James; Pfefferkorn, Marian D.; Rosh, Joel R.; Boyle, Brendan M.; Mack, David R.; Baldassano, Robert N.; Shah, Sapana; LeLeiko, Neal S.; Heyman, Melvin B.; Griffiths, Anne M.; Patel, Ashish S.; Noe, Joshua D.; Davis Thomas, Sonia; Aronow, Bruce J.; Walters, Thomas D.; McGovern, Dermot P.B.; Hyams, Jeffrey S.; Kugathasan, Subra; Cho, Judy H.; Denson, Lee A.; Gibson, Greg; Pediatrics, School of Medicine
    An important goal of clinical genomics is to be able to estimate the risk of adverse disease outcomes. Between 5% and 10% of individuals with ulcerative colitis (UC) require colectomy within 5 years of diagnosis, but polygenic risk scores (PRSs) utilizing findings from genome-wide association studies (GWASs) are unable to provide meaningful prediction of this adverse status. By contrast, in Crohn disease, gene expression profiling of GWAS-significant genes does provide some stratification of risk of progression to complicated disease in the form of a transcriptional risk score (TRS). Here, we demonstrate that a measured TRS based on bulk rectal gene expression in the PROTECT inception cohort study has a positive predictive value approaching 50% for colectomy. Single-cell profiling demonstrates that the genes are active in multiple diverse cell types from both the epithelial and immune compartments. Expression quantitative trait locus (QTL) analysis identifies genes with differential effects at baseline and week 52 follow-up, but for the most part, differential expression associated with colectomy risk is independent of local genetic regulation. Nevertheless, a predicted polygenic transcriptional risk score (PPTRS) derived by summation of transcriptome-wide association study (TWAS) effects identifies UC-affected individuals at 5-fold elevated risk of colectomy with data from the UK Biobank population cohort studies, independently replicated in an NIDDK-IBDGC dataset. Prediction of gene expression from relatively small transcriptome datasets can thus be used in conjunction with TWASs for stratification of risk of disease complications.
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    Ulcerative colitis mucosal transcriptomes reveal mitochondriopathy and personalized mechanisms underlying disease severity and treatment response
    (Springer Nature, 2019-01-03) Haberman, Yael; Karns, Rebekah; Dexheimer, Phillip J.; Schirmer, Melanie; Somekh, Judith; Jurickova, Ingrid; Braun, Tzipi; Novak, Elizabeth; Bauman, Laura; Collins, Margaret H.; Mo, Angela; Rosen, Michael J.; Bonkowski, Erin; Gotman, Nathan; Marquis, Alison; Nistel, Mason; Rufo, Paul A.; Baker, Susan S.; Sauer, Cary G.; Markowitz, James; Pfefferkorn, Marian D.; Rosh, Joel R.; Boyle, Brendan M.; Mack, David R.; Baldassano, Robert N.; Shah, Sapana; Leleiko, Neal S.; Heyman, Melvin B.; Grifiths, Anne M.; Patel, Ashish S.; Noe, Joshua D.; Aronow, Bruce J.; Kugathasan, Subra; Walters, Thomas D.; Gibson, Greg; Thomas, Sonia Davis; Mollen, Kevin; Shen-Orr, Shai; Huttenhower, Curtis; Xavier, Ramnik J.; Hyams, Jeffrey S.; Denson, Lee A.; Pediatrics, School of Medicine
    Molecular mechanisms driving disease course and response to therapy in ulcerative colitis (UC) are not well understood. Here, we use RNAseq to define pre-treatment rectal gene expression, and fecal microbiota profiles, in 206 pediatric UC patients receiving standardised therapy. We validate our key findings in adult and paediatric UC cohorts of 408 participants. We observe a marked suppression of mitochondrial genes and function across cohorts in active UC, and that increasing disease severity is notable for enrichment of adenoma/adenocarcinoma and innate immune genes. A subset of severity genes improves prediction of corticosteroid-induced remission in the discovery cohort; this gene signature is also associated with response to anti-TNFα and anti-α4β7 integrin in adults. The severity and therapeutic response gene signatures were in turn associated with shifts in microbes previously implicated in mucosal homeostasis. Our data provide insights into UC pathogenesis, and may prioritise future therapies for nonresponders to current approaches.