My Recent Publications
<em>gene2gauss</em>: A multi-view gaussian gene embedding learner for analyzing transcriptomic networks
AMIA Annu Symp Proc. 2022 May 23;2022:206-215. eCollection 2022.
Analyzing gene co-expression networks can help in the discovery of biological processes and regulatory mechanisms underlying normal or perturbed states. Unlike standard differential analysis, network-based approaches consider the interactions between the genes involved leading to biologically relevant results. Applying such network-based methods to jointly analyze multiple transcriptomic networks representing independent disease cohorts or studies could lead to the identification of more robust gene modules or gene regulatory networks. We present gene2gauss, a novel feature learning framework that is capable of embedding genes as multivariate gaussian distributions by taking into account their long-range interaction neighborhoods across multiple transcriptomic studies. Using multiple gene co-expression networks from idiopathic pulmonary fibrosis, we demonstrate that these multi-dimensional gaussian features are suitable for identifying regulons of known transcription factors (TF). Using standard TF-target libraries, we demonstrate that the features from our method are highly relevant in comparison with other feature learning approaches on transcriptomic data.
Front Genet. 2022 Jun 27;13:896117. doi: 10.3389/fgene.2022.896117. eCollection 2022.
Myosin binding protein-C (MyBP-C) is a sarcomeric protein which regulates the force of contraction in striated muscles. Mutations in the MYBPC family of genes, including slow skeletal (MYBPC1), fast skeletal (MYBPC2) and cardiac (MYBPC3), can result in cardiac and skeletal myopathies. Nonetheless, their evolutionary pattern, pathogenicity and impact on MyBP-C protein structure remain to be elucidated. Therefore, the present study aimed to systematically assess the evolutionarily conserved and epigenetic patterns of MYBPC family mutations. Leveraging a machine learning (ML) approach, the Genome Aggregation Database (gnomAD) provided variants in MYBPC1, MYBPC2, and MYBPC3 genes. This was followed by an analysis with Ensembl's variant effect predictor (VEP), resulting in the identification of 8,618, 3,871, and 3,071 variants in MYBPC1, MYBPC2, and MYBPC3, respectively. Missense variants comprised 61%-66% of total variants in which the third nucleotide positions in the codons were highly altered. Arginine was the most mutated amino acid, important because most disease-causing mutations in MyBP-C proteins are arginine in origin. Domains C5 and C6 of MyBP-C were found to be hotspots for most mutations in the MyBP-C family of proteins. A high percentage of truncated mutations in cMyBP-C cause cardiomyopathies. Arginine and glutamate were the top hits in fMyBP-C and cMyBP-C, respectively, and tryptophan and tyrosine were the most common among the three paralogs changing to premature stop codons and causing protein truncations at the carboxyl terminus. A heterogeneous epigenetic pattern was identified among the three MYBP-C paralogs. Overall, it was shown that databases using computational approaches can facilitate diagnosis and drug discovery to treat muscle disorders caused by MYBPC mutations.
Defining the Dynamic Regulation of O-GlcNAc Proteome in the Mouse Cortex---the O-GlcNAcylation of Synaptic and Trafficking Proteins Related to Neurodegenerative Diseases
Front Aging. 2021 Sep 29;2:757801. doi: 10.3389/fragi.2021.757801. eCollection 2021.
O-linked conjugation of ß-N-acetyl-glucosamine (O-GlcNAc) to serine and threonine residues is a post-translational modification process that senses nutrient availability and cellular stress and regulates diverse biological processes that are involved in neurodegenerative diseases and provide potential targets for therapeutics development. However, very little is known of the networks involved in the brain that are responsive to changes in the O-GlcNAc proteome. Pharmacological increase of protein O-GlcNAcylation by Thiamet G (TG) has been shown to decrease tau phosphorylation and neurotoxicity, and proposed as a therapy in Alzheimer's disease (AD). However, acute TG exposure impairs learning and memory, and protein O-GlcNAcylation is increased in the aging rat brain and in Parkinson's disease (PD) brains. To define the cortical O-GlcNAc proteome that responds to TG, we injected young adult mice with either saline or TG and performed mass spectrometry analysis for detection of O-GlcNAcylated peptides. This approach identified 506 unique peptides corresponding to 278 proteins that are O-GlcNAcylated. Of the 506 unique peptides, 85 peptides are elevated by > 1.5 fold in O-GlcNAcylation levels in response to TG. Using pathway analyses, we found TG-dependent enrichment of O-GlcNAcylated synaptic proteins, trafficking, Notch/Wnt signaling, HDAC signaling, and circadian clock proteins. Significant changes in the O-GlcNAcylation of DNAJC6/AUXI, and PICALM, proteins that are risk factors for PD and/or AD respectively, were detected. We compared our study with two key prior O-GlcNAc proteome studies using mouse cerebral tissue and human AD brains. Among those identified to be increased by TG, 15 are also identified to be increased in human AD brains compared to control, including those involved in cytoskeleton, autophagy, chromatin organization and mitochondrial dysfunction. These studies provide insights regarding neurodegenerative diseases therapeutic targets.
Is There a Benefit From Islet Autotransplantation in Patients With Type 1 Diabetes Mellitus Undergoing Total Pancreatectomy?
Pancreas. 2022 Apr 1;51(4):399-403. doi: 10.1097/MPA.0000000000002017.
Children with acute recurrent and chronic pancreatitis (CP) experience abdominal pain that leads to hospitalizations, opioid dependence, and poor quality of life. Total pancreatectomy with islet autotransplantation (TPIAT) is offered as a surgical option in management of debilitating pancreatitis that fails medical and endoscopic therapy to reduce or eliminate pain. Given that patients with type 1 diabetes mellitus (T1DM) lack insulin-producing β cells, the outcomes from autotransplanting islet isolates back into total pancreatectomy patients with T1DM are not fully known.We performed TPIAT in 2 CP patients who also had a diagnosis of T1DM for at least 6 years before the operation and evaluated the clinical and laboratory outcomes before and after the operation. Postoperatively both patients' abdominal pain had significantly subsided, they were weaned off opioid medications, and they were able to return to full-time school attendance. In addition, total daily dose of insulin in 1 patient was able to be slightly reduced at 12 months post-TPIAT. We observed in vitro that residual α cells and β cells in T1DM islets were able to secrete a small amount of glucagon and insulin, respectively.
Targeted Assessment of Mucosal Immune Gene Expression Predicts Clinical Outcomes in Children with Ulcerative Colitis
J Crohns Colitis. 2022 Jun 4:jjac075. doi: 10.1093/ecco-jcc/jjac075. Online ahead of print.
BACKGROUND AND AIMS: We aimed to determine whether a targeted gene expression panel could predict clinical outcomes in pediatric UC and investigated putative pathogenic roles of predictive genes.
METHODS: 313 rectal RNA samples from a cohort of newly diagnosed pediatric UC patients (PROTECT) were analyzed by a real-time PCR microfluidic array for expression of type 1, 2, and 17 inflammation genes. Associations between expression and clinical outcomes were assessed by logistic regression. Identified prognostic markers were further analyzed using existing RNA sequencing (RNA-seq) data sets and tissue immunostaining.
RESULTS: IL13RA2 was associated with lower likelihood of corticosteroid-free remission (CSFR) on mesalamine at week 52 (P= .002). A model including IL13RA2 and only baseline clinical parameters was as accurate as an established clinical model, which requires week 4 remission status. RORC was associated with lower likelihood of colectomy by week 52. A model including RORC and PUCAI predicted colectomy by 52 weeks (AUC 0.71). Bulk RNA-seq identified IL13RA2 and RORC as hub genes within UC outcome-associated expression networks related to extracellular matrix and innate immune response, and lipid metabolism and microvillus assembly, respectively. Adult UC single-cell RNA-seq data revealed IL13RA2 and RORC co-expressed genes were localized to inflammatory fibroblasts and undifferentiated epithelial cells, respectively, which was supported by protein immunostaining.
CONCLUSION: Targeted assessment of rectal mucosal immune gene expression predicts 52-week CSFR in treatment-naïve pediatric UC patients. Further exploration of IL-13Rɑ2 as a therapeutic target in UC, and future studies of the epithelial-specific role of RORC in UC pathogenesis are warranted.
Consensus Gene Co-Expression Network Analysis Identifies Novel Genes Associated with Severity of Fibrotic Lung Disease
Int J Mol Sci. 2022 May 13;23(10):5447. doi: 10.3390/ijms23105447.
Idiopathic pulmonary fibrosis (IPF) is a severe fibrotic lung disease characterized by irreversible scarring of the lung parenchyma leading to dyspnea, progressive decline in lung function, and respiratory failure. We analyzed lung transcriptomic data from independent IPF cohorts using weighted gene co-expression network analysis (WGCNA) to identify gene modules based on their preservation status in these cohorts. The consensus gene modules were characterized by leveraging existing clinical and molecular data such as lung function, biological processes, pathways, and lung cell types. From a total of 32 consensus gene modules identified, two modules were found to be significantly correlated with the disease, lung function, and preserved in other IPF datasets. The upregulated gene module was enriched for extracellular matrix, collagen metabolic process, and BMP signaling while the downregulated module consisted of genes associated with tube morphogenesis, blood vessel development, and cell migration. Using a combination of connectivity-based and trait-based significance measures, we identified and prioritized 103 "hub" genes (including 25 secretory candidate biomarkers) by their similarity to known IPF genetic markers. Our validation studies demonstrate the dysregulated expression of CRABP2, a retinol-binding protein, in multiple lung cells of IPF, and its correlation with the decline in lung function.
Rewiring of 3D Chromatin Topology Orchestrates Transcriptional Reprogramming and the Development of Human Dilated Cardiomyopathy
Circulation. 2022 Apr 11. doi: 10.1161/CIRCULATIONAHA.121.055781. Online ahead of print.
Background: Transcriptional reconfiguration is central to heart failure, the common cause of which is dilated cardiomyopathy (DCM). However, the impact of three-dimensional (3D) chromatin topology on transcriptional dysregulation and pathogenesis in human DCM remains elusive. Methods: We generated a compendium of 3D-epigenome and transcriptome maps from 101 biobanked human DCM and non-failing heart tissues through HiChIP (H3K27ac), in situ Hi-C, ChIP-seq, ATAC-seq and RNA-seq profiling. We employed human iPSC-derived cardiomyocytes (hiPSC-CMs) and mouse models to further interrogate the key transcription factor implicated in 3D chromatin organization and transcriptional regulation in DCM pathogenesis. Results: We discovered that the active regulatory elements (H3K27ac peaks) and their connectome (H3K27ac loops) were extensively reprogrammed in DCM hearts and contributed to transcriptional dysregulation implicated for DCM development. For example, we identified that non-transcribing NPPA-AS1 promoter functions as an enhancer and physically interacts with the NPPA and NPPB promoters, leading to the co-transcription of NPPA and NPPB in DCM hearts. We uncovered that DCM-enriched H3K27ac loops largely resided in conserved high-order chromatin architectures (Compartments, Topologically Associating Domains) and unexpectedly their anchors had equivalent chromatin accessibility. Intriguingly, we discovered that the DCM-enriched H3K27ac loop anchors exhibited a strong enrichment for Heart and Neural Crest Derivatives Expressed 1 (HAND1), a key transcription factor involved in early cardiogenesis. In line with this, its protein expression was upregulated in human DCM and mouse failing hearts. To further validate whether HAND1 is a causal driver for the reprogramming of enhancer/promoter connectome in DCM hearts, we performed comprehensive 3D epigenome mappings in hiPSC-CMs. We found that forced overexpression of HAND1 in hiPSC-CM induced a distinct gain of enhancer/promoter connectivity and, correspondingly, increased the expression of their connected genes implicated in DCM etiology, thus recapitulating the transcriptional signature in human DCM hearts. Moreover, electrophysiology analysis demonstrated that forced overexpression of HAND1 in hiPSC-CM induced abnormal calcium handling. Furthermore, cardiomyocyte-specific overexpression of Hand1 in the mouse hearts resulted in a dilated cardiac remodeling with impaired contractility/Ca2+ handling in cardiomyocytes, increased ratio of heart weight/body weight and compromised cardiac function, which were ascribed to recapitulation of transcriptional reprogramming in DCM. Conclusions: This study provided novel chromatin topology insights into DCM pathogenesis and illustrated a model whereby a single transcription factor (HAND1) reprograms the genome-wide enhancer/promoter connectome to drive DCM pathogenesis.
Eicosatetraynoic Acid and Butyrate Regulate Human Intestinal Organoid Mitochondrial and Extracellular Matrix Pathways Implicated in Crohn's Disease Strictures
Inflamm Bowel Dis. 2022 Mar 8:izac037. doi: 10.1093/ibd/izac037. Online ahead of print.
BACKGROUND: Perturbagen analysis of Crohn's disease (CD) ileal gene expression data identified small molecules including eicosatetraynoic acid (ETYA), which may exert an antifibrotic effect. We developed a patient-specific human intestinal organoid (HIO) model system to test small molecule regulation of mitochondrial and wound-healing functions implicated in stricturing behavior.
METHODS: HIOs were made from CD induced pluripotent stem cells with and without a loss-of-function haplotype in the DUOX2 gene implicated in ileal homeostasis and characterized under basal conditions and following exposure to butyrate and ETYA using RNA sequencing, flow cytometry, and immunofluorescent and polarized light microscopy. Mitochondrial activity was measured using high-resolution respirometry and tissue stiffness using atomic force microscopy.
RESULTS: HIOs expressed core mitochondrial and extracellular matrix (ECM) genes and enriched biologic functions implicated in CD ileal strictures; ECM gene expression was suppressed by both butyrate and ETYA, with butyrate also suppressing genes regulating epithelial proliferation. Consistent with this, butyrate, but not ETYA, exerted a profound effect on HIO epithelial mitochondrial function, reactive oxygen species production, and cellular abundance. Butyrate and ETYA suppressed HIO expression of alpha smooth muscle actin expressed by myofibroblasts, type I collagen, and collagen protein abundance. HIOs exhibited tissue stiffness comparable to normal human ileum; this was reduced by chronic ETYA exposure in HIOs carrying the DUOX2 loss-of-function haplotype.
CONCLUSIONS: ETYA regulates ECM genes implicated in strictures and suppresses collagen content and tissue stiffness in an HIO model. HIOs provide a platform to test personalized therapeutics, including small molecules prioritized by perturbagen analysis.
STAR Protoc. 2021 Sep 24;2(4):100873. doi: 10.1016/j.xpro.2021.100873. eCollection 2021 Dec 17.
Standard transcriptomic analyses cannot fully capture the molecular mechanisms underlying disease pathophysiology and outcomes. We present a computational heterogeneous data integration and mining protocol that combines transcriptional signatures from multiple model systems, protein-protein interactions, single-cell RNA-seq markers, and phenotype-genotype associations to identify functional feature complexes. These feature modules represent a higher order multifeatured machines collectively working toward common pathophysiological goals. We apply this protocol for functional characterization of COVID-19, but it could be applied to many other diseases. For complete details on the use and execution of this protocol, please refer to Ghandikota et al. (2021).
Pediatr Pulmonol. 2021 Sep 29. doi: 10.1002/ppul.25709. Online ahead of print.
INTRODUCTION: Rubinstein-Taybi syndrome (RSTS) is a rare genetic syndrome caused primarily by a mutation in the CREBBP gene found on chromosome 16. Patients with RSTS are at greater risk for a variety of medical problems, including upper airway obstruction and aspiration. Childhood interstitial lung disease (ILD) thus far has not been definitively linked to RSTS. Here we present three patients with RSTS who developed ILD and discuss possible mechanisms by which a mutation in CREBBP may be involved in the development of ILD.
METHODS: Routine hematoxylin and eosin staining was performed on lung biopsy tissue for histological analysis. Immunofluorescent staining was performed on lung biopsy tissue for markers of fibrosis, surfactant deficiency and histone acetylation. Cases 1 and 2 had standard clinical microarray analysis. Case 3 had whole exome sequencing. Bioinformatics analyses were performed to identify possible causative genes using ToppGene.
RESULTS: CT images in all cases showed consolidated densities overlying ground glass opacities. Lung histopathology revealed accumulation of proteinaceous material within alveolar spaces, evidence of fibrosis, and increased alveolar macrophages. Immunofluorescent staining showed increase in surfactant protein C staining, patchy areas of increased aSMA staining, and increased staining for acetylated histone 2 and histone 3 lysine 9.
DISCUSSION: Clinical characteristics, radiographic imaging, lung histopathology, and immunofluorescent staining results shared by all cases demonstrated findings consistent with ILD. Immunofluorescent staining suggests two possible mechanisms for the development of ILD: abnormal surfactant metabolism and/or persistent activation of myofibroblasts. These two pathways could be related to dysfunctional CREBBP protein. This article is protected by copyright. All rights reserved.
JCI Insight. 2021 Sep 14:152503. doi: 10.1172/jci.insight.152503. Online ahead of print.
Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease associated with unremitting fibroblast activation including fibroblast-to-myofibroblast transformation (FMT), migration, resistance to apoptotic clearance, and excessive deposition of extracellular matrix (ECM) proteins in the distal lung parenchyma. Aberrant activation of lung-developmental pathways is associated with severe fibrotic lung disease; however, the mechanisms through which these pathways activate fibroblasts in IPF remain unclear. Sox9 is a member of the HMG box family of DNA-binding transcription factors that are selectively expressed by epithelial cell progenitors to modulate branching morphogenesis during lung development. We demonstrate that Sox9 is upregulated via MAPK/PI3K-dependent signaling and by the transcription factor Wilms' tumor 1 in distal lung-resident fibroblasts in IPF. Mechanistically, using fibroblast activation assays, we demonstrate that Sox9 functions as a positive regulator of FMT, migration, survival, and ECM production. Importantly, our in vivo studies demonstrate that fibroblast-specific deletion of Sox9 is sufficient to attenuate collagen deposition and improve lung function during TGFα-induced pulmonary fibrosis. Using a mouse model of bleomycin-induced pulmonary fibrosis, we show that myofibroblast-specific Sox9 overexpression augments fibroblast activation and pulmonary fibrosis. Thus, Sox9 functions as a profibrotic transcription factor in activating fibroblasts, illustrating the potential utility of targeting Sox9 in IPF treatment.
Thorax. 2021 Aug 16:thoraxjnl-2021-216882. doi: 10.1136/thoraxjnl-2021-216882. Online ahead of print.
BACKGROUND: The role of club cells in the pathology of idiopathic pulmonary fibrosis (IPF) is not well understood. Protein disulfide isomerase A3 (PDIA3), an endoplasmic reticulum-based redox chaperone required for the functions of various fibrosis-related proteins; however, the mechanisms of action of PDIA3 in pulmonary fibrosis are not fully elucidated.
OBJECTIVES: To examine the role of club cells and PDIA3 in the pathology of pulmonary fibrosis and the therapeutic potential of inhibition of PDIA3 in lung fibrosis.
METHODS: Role of PDIA3 and aberrant club cells in lung fibrosis was studied by analyses of human transcriptome dataset from Lung Genomics Research Consortium, other public resources, the specific deletion or inhibition of PDIA3 in club cells and blocking SPP1 downstream of PDIA3 in mice.
RESULTS: PDIA3 and club cell secretory protein (SCGB1A1) signatures are upregulated in IPF compared with control patients. PDIA3 or SCGB1A1 increases also correlate with a decrease in lung function in patients with IPF. The bleomycin (BLM) model of lung fibrosis showed increases in PDIA3 in SCGB1A1 cells in the lung parenchyma. Ablation of Pdia3, specifically in SCGB1A1 cells, decreases parenchymal SCGB1A1 cells along with fibrosis in mice. The administration of a PDI inhibitor LOC14 reversed the BLM-induced parenchymal SCGB1A1 cells and fibrosis in mice. Evaluation of PDIA3 partners revealed that SPP1 is a major interactor in fibrosis. Blocking SPP1 attenuated the development of lung fibrosis in mice.
CONCLUSIONS: Our study reveals a new relationship with distally localised club cells, PDIA3 and SPP1 in lung fibrosis and inhibition of PDIA3 or SPP1 attenuates lung fibrosis.
Ileal derived organoids from Crohn's disease patients show unique transcriptomic and secretomic signatures
Cell Mol Gastroenterol Hepatol. 2021 Jul 13:S2352-345X(21)00133-8. doi: 10.1016/j.jcmgh.2021.06.018. Online ahead of print.
BACKGROUND: We used patient derived organoids (PDOs) to study the epithelial-specific transcriptional and secretome signatures of the ileum during CD with varying phenotypes to screen for disease profiles and potential druggable targets.
METHODS: RNA sequencing was performed on isolated intestinal crypts and 3-week-old PDOs derived from ileal biopsies of CD patients (n= 8 B1, inflammatory; n= 8 B2, stricturing disease) and non-IBD controls (n= 13). Differentially expressed (DE) genes were identified by comparing CD vs control, B1 vs B2, and inflamed vs non-inflamed. DE genes were used for computational screening to find candidate small molecules that could potentially reverse B1and B2 gene signatures. The secretome of a second cohort (n= 6 non-IBD controls, n=7 CD; 5 non-inflamed, 2 inflamed) was tested by Luminex using cultured organoid conditioned media.
RESULTS: We found a 90% similarity in both the identity and abundance of protein coding genes between PDOs and intestinal crypts (15,554 transcripts of 19,900 genes). DE analysis identified 814 genes among disease group (CD vs non-IBD control), 470 genes different between the CD phenotypes, and 5 FDR significant genes between inflamed and non-inflamed CD. The PDOs showed both similarity and diversity in the levels and types of soluble cytokines and growth factors they released. Perturbagen analysis revealed potential candidate compounds to reverse B2 disease phenotype to B1 in PDOs.
CONCLUSION: PDOs are similar at the transcriptome level with the in vivo epithelium and retain disease-specific gene expression for which we have identified secretome products, druggable targets and corresponding pharmacological agents. Targeting the epithelium could reverse a stricturing phenotype and improve outcomes.
IEEE/ACM Trans Comput Biol Bioinform. 2021 May 20;PP. doi: 10.1109/TCBB.2021.3082466. Online ahead of print.
In-silico drug repositioning or predicting new indications for approved or late-stage clinical trial drugs is a resourceful and time-ecient strategy in drug discovery. However, inferring novel candidate drugs for a disease is challenging, given the heterogeneity and sparseness of the underlying biological entities and their relationships (e.g., disease/drug annotations). By integrating drug-centric and disease-centric annotations as multiviews, we propose a multi-view graph attention network for indication discovery (MGATRx). Unlike most current similaritybased methods, we employ graph attention network on the heterogeneous drug and disease data to learn the representation of nodes and identify associations. MGATRx outperformed four other state-of-art methods used for computational drug repositioning. Further, several of our predicted novel indications are either currently investigated or are supported by literature evidence, demonstrating the overall translational utility of MGATRx.
Esomeprazole attenuates inflammatory and fibrotic response in lung cells through the MAPK/Nrf2/HO1 pathway
J Inflamm (Lond). 2021 May 19;18(1):17. doi: 10.1186/s12950-021-00284-6.
INTRODUCTION: Idiopathic pulmonary fibrosis (IPF) is an orphan disease characterized by progressive loss of lung function resulting in shortness of breath and often death within 3-4 years of diagnosis. Repetitive lung injury in susceptible individuals is believed to promote chronic oxidative stress, inflammation, and uncontrolled collagen deposition. Several preclinical and retrospective clinical studies in IPF have reported beneficial outcomes associated with the use of proton pump inhibitors (PPIs) such as esomeprazole. Accordingly, we sought to investigate molecular mechanism(s) by which PPIs favorably regulate the disease process.
METHODS: We stimulated oxidative stress, pro-inflammatory and profibrotic phenotypes in primary human lung epithelial cells and fibroblasts upon treatment with bleomycin or transforming growth factor β (TGFβ) and assessed the effect of a prototype PPI, esomeprazole, in regulating these processes.
RESULTS: Our study shows that esomeprazole controls pro-inflammatory and profibrotic molecules through nuclear translocation of the transcription factor nuclear factor-like 2 (Nrf2) and induction of the cytoprotective molecule heme oxygenase 1 (HO1). Genetic deletion of Nrf2 or pharmacological inhibition of HO1 impaired esomeprazole-mediated regulation of proinflammatory and profibrotic molecules. Additional studies indicate that activation of Mitogen Activated Protein Kinase (MAPK) pathway is involved in the process. Our experimental data was corroborated by bioinformatics studies of an NIH chemical library which hosts gene expression profiles of IPF lung fibroblasts treated with over 20,000 compounds including esomeprazole. Intriguingly, we found 45 genes that are upregulated in IPF but downregulated by esomeprazole. Pathway analysis showed that these genes are enriched for profibrotic processes. Unbiased high throughput RNA-seq study supported antifibrotic effect of esomeprazole and revealed several novel targets.
CONCLUSIONS: Taken together, PPIs may play antifibrotic role in IPF through direct regulation of the MAPK/Nrf2/HO1 pathway to favorably influence the disease process in IPF.
Systems Biology Guided Gene Enrichment Approaches Improve Prediction of Chronic Post-surgical Pain After Spine Fusion
Front Genet. 2021 Mar 23;12:594250. doi: 10.3389/fgene.2021.594250. eCollection 2021.
OBJECTIVES: Incorporation of genetic factors in psychosocial/perioperative models for predicting chronic postsurgical pain (CPSP) is key for personalization of analgesia. However, single variant associations with CPSP have small effect sizes, making polygenic risk assessment important. Unfortunately, pediatric CPSP studies are not sufficiently powered for unbiased genome wide association (GWAS). We previously leveraged systems biology to identify candidate genes associated with CPSP. The goal of this study was to use systems biology prioritized gene enrichment to generate polygenic risk scores (PRS) for improved prediction of CPSP in a prospectively enrolled clinical cohort.
METHODS: In a prospectively recruited cohort of 171 adolescents (14.5 ± 1.8 years, 75.4% female) undergoing spine fusion, we collected data about anesthesia/surgical factors, childhood anxiety sensitivity (CASI), acute pain/opioid use, pain outcomes 6-12 months post-surgery and blood (for DNA extraction/genotyping). We previously prioritized candidate genes using computational approaches based on similarity for functional annotations with a literature-derived "training set." In this study, we tested ranked deciles of 1336 prioritized genes for increased representation of variants associated with CPSP, compared to 10,000 randomly selected control sets. Penalized regression (LASSO) was used to select final variants from enriched variant sets for calculation of PRS. PRS incorporated regression models were compared with previously published non-genetic models for predictive accuracy.
RESULTS: Incidence of CPSP in the prospective cohort was 40.4%. 33,104 case and 252,590 control variants were included for association analyses. The smallest gene set enriched for CPSP had 80/1010 variants associated with CPSP (p < 0.05), significantly higher than in 10,000 randomly selected control sets (p = 0.0004). LASSO selected 20 variants for calculating weighted PRS. Model adjusted for covariates including PRS had AUROC of 0.96 (95% CI: 0.92-0.99) for CPSP prediction, compared to 0.70 (95% CI: 0.59-0.82) for non-genetic model (p < 0.001). Odds ratios and positive regression coefficients for the final model were internally validated using bootstrapping: PRS [OR 1.98 (95% CI: 1.21-3.22); β 0.68 (95% CI: 0.19-0.74)] and CASI [OR 1.33 (95% CI: 1.03-1.72); β 0.29 (0.03-0.38)].
DISCUSSION: Systems biology guided PRS improved predictive accuracy of CPSP risk in a pediatric cohort. They have potential to serve as biomarkers to guide risk stratification and tailored prevention. Findings highlight systems biology approaches for deriving PRS for phenotypes in cohorts less amenable to large scale GWAS.
Patterns (N Y). 2021 Apr 5:100247. doi: 10.1016/j.patter.2021.100247. Online ahead of print.
Standard transcriptomic analyses alone have limited power in capturing the molecular mechanisms driving disease pathophysiology and outcomes. To overcome this, unsupervised network analyses are used to identify clusters of genes that can be associated with distinct molecular mechanisms and outcomes for a disease. In this study, we developed an integrated network analysis framework that integrates transcriptional signatures from multiple model systems with protein-protein interaction data to find gene modules. Through a meta-analysis of different enriched features from these gene modules, we extract communities of highly interconnected features. These clusters of higher-order features, working as a multifeatured machine, enable collective assessment of their contribution for disease or phenotype characterization. We show the utility of this workflow using transcriptomics data from three different models of SARS-CoV-2 infection and identify several pathways and biological processes that could enable in understanding or hypothesizing molecular signatures inducing pathophysiological changes, risks, or sequelae of COVID-19.
Front Immunol. 2021 Mar 19;12:645717. doi: 10.3389/fimmu.2021.645717. eCollection 2021.
Idiopathic Pulmonary Fibrosis (IPF) is a severe fibrotic lung disease characterized by excessive collagen deposition and progressive decline in lung function. Th2 T cell-derived cytokines including IL-4 and IL-13 have been shown to contribute to inflammation and fibrotic remodeling in multiple tissues. Interleukin-31 (IL-31) is a newly identified cytokine that is predominantly produced by CD4 Th2 T cells, but its signaling receptor IL-31RA is primarily expressed by non-hematopoietic cells. However, the potential role of the IL-31-IL31RA axis in pulmonary inflammation and fibrosis has remained largely unknown. To determine the role of IL-31RA deficiency in pulmonary fibrosis, wildtype, and IL-31RA knockout mice were treated with bleomycin and measured changes in collagen deposition and lung function. Notably, the loss of IL-31 signaling attenuated collagen deposition and lung function decline during bleomycin-induced pulmonary fibrosis. The total lung transcriptome analysis showed a significant reduction in fibrosis-associated gene transcripts including extracellular matrix and epithelial cell-associated gene networks. Furthermore, the lungs of human IPF showed an elevated expression of IL-31 when compared to healthy subjects. In support, the percentage of IL-31 producing CD4+ T cells was greater in the lungs and PBMCs from IPF patients compared to healthy controls. Our findings suggest a pathogenic role for IL-31/IL-31RA signaling during bleomycin-induced pulmonary fibrosis. Thus, therapeutic targeting the IL-31-IL-31RA axis may prevent collagen deposition, improve lung function, and have therapeutic potential in pulmonary fibrosis.
Mucosal Genomics Implicate Lymphocyte Activation and Lipid Metabolism in Refractory Environmental Enteric Dysfunction
Gastroenterology. 2021 Jan 29:S0016-5085(21)00327-9. doi: 10.1053/j.gastro.2021.01.221. Online ahead of print.
BACKGROUND & AIMS: Environmental enteric dysfunction (EED) limits the Sustainable Development Goals of improved childhood growth and survival. We applied mucosal genomics to advance our understanding of EED.
METHODS: The Study of Environmental Enteropathy and Malnutrition (SEEM) followed 416 children from birth to 24 months in a rural district in Pakistan. Biomarkers were measured at 9 months and tested for association with growth at 24 months. The duodenal methylome and transcriptome was determined in 52 undernourished SEEM participants and 42 North American controls and celiac disease patients.
RESULTS: After accounting for growth at study entry, circulating IGF-1 and ferritin predicted linear growth, whereas leptin correlated with future weight gain. The EED transcriptome exhibited suppression of antioxidant, detoxification, and lipid metabolism genes, and induction of anti-microbial response, interferon, and lymphocyte activation genes. Relative to celiac disease, suppression of antioxidant and detoxification genes and induction of anti-microbial response genes were EED-specific. At the epigenetic level, EED showed hyper-methylation of epithelial metabolism and barrier function genes, and hypo-methylation of immune response and cell proliferation genes. Duodenal co-expression modules showed association between lymphocyte proliferation and epithelial metabolic genes and histologic severity, fecal energy loss, and wasting (weight-for-length/height Z<-2.0). Leptin was associated with expression of epithelial carbohydrate metabolism and stem cell renewal genes. Immune response genes were attenuated by giardia colonization.
CONCLUSIONS: Children with reduced circulating IGF-1 are more likely to experience stunting. Leptin and a gene signature for lymphocyte activation and dysregulated lipid metabolism are implicated in wasting, suggesting new approaches for EED refractory to nutritional intervention.
Association of Baseline Luminal Narrowing With Ileal Microbial Shifts and Gene Expression Programs and Subsequent Transmural Healing in Pediatric Crohn Disease
Inflamm Bowel Dis. 2021 Jan 16:izaa339. doi: 10.1093/ibd/izaa339. Online ahead of print.
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.