Biofilm formation in a Gram-negative prosthetic joint infection model
In this issue of JCI Insight, Thompson et al. developed a murine model of Gram-negative prosthetic joint infection in which an orthopaedic-grade titanium implant was placed in the femur followed by infection with
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Review
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Abstract
The disabling degenerative disease osteoarthritis (OA) is prevalent among the global population. Articular cartilage degeneration is a central feature of OA; therefore, a better understanding of the mechanisms that maintain cartilage homeostasis is vital for developing effective therapeutic interventions. MicroRNAs (miRs) modulate cell signaling pathways and various processes in articular cartilage via posttranscriptional repression of target genes. As dysregulated miRs frequently alter the homeostasis of articular cartilage, modulating select miRs presents a potential therapeutic opportunity for OA. Here, we review key miRs that have been shown to modulate cartilage-protective or -destructive mechanisms and signaling pathways. Additionally, we use an integrative computational biology approach to provide insight into predicted miR gene targets that may contribute to OA pathogenesis, and highlight the complexity of miR signaling in OA by generating both unique and overlapping gene targets of miRs that mediate protective or destructive effects. Early OA detection would enable effective prevention; thus, miRs are being explored as diagnostic biomarkers. We discuss these ongoing efforts and the applicability of miR mimics and antisense inhibitors as potential OA therapeutics.
Authors
Helal Endisha, Jason Rockel, Igor Jurisica, Mohit Kapoor
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Research Articles
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Abstract
Hemorrhagic shock depletes nicotinamide adenine dinucleotide (NAD) and causes metabolic derangements that, in severe cases, cannot be overcome, even after restoration of blood volume and pressure. However, current strategies to treat acute blood loss do not target cellular metabolism. We hypothesized that supplemental nicotinamide mononucleotide (NMN), the immediate biosynthetic precursor to NAD, would support cellular energetics and enhance physiologic resilience to hemorrhagic shock. In a rodent model of decompensated hemorrhagic shock, rats receiving NMN displayed significantly reduced lactic acidosis and serum IL-6 levels, two strong predictors of mortality in human patients. In both livers and kidneys, NMN increased NAD levels and prevented mitochondrial dysfunction. Moreover, NMN preserved mitochondrial function in isolated hepatocytes cocultured with proinflammatory cytokines, indicating a cell-autonomous protective effect that is independent from the reduction in circulating IL-6. In kidneys, but not in livers, NMN was sufficient to prevent ATP loss following shock and resuscitation. Overall, NMN increased the time animals could sustain severe shock before requiring resuscitation by nearly 25% and significantly improved survival after resuscitation (P = 0.018), whether NMN was given as a pretreatment or only as an adjunct during resuscitation. Thus, we demonstrate that NMN substantially mitigates inflammation, improves cellular metabolism, and promotes survival following hemorrhagic shock.
Authors
Carrie A. Sims, Yuxia Guan, Sarmistha Mukherjee, Khushboo Singh, Paul Botolin, Antonio Davila Jr., Joseph A. Baur
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Lipocalin-2 is not only a sensitive biomarker, but it also contributes to the pathogenesis of renal injuries. The present study demonstrates that adipose tissue–derived lipocalin-2 plays a critical role in causing both chronic and acute renal injuries. Four-week treatment with aldosterone and high salt after uninephrectomy (ANS) significantly increased both circulating and urinary lipocalin-2, and it induced glomerular and tubular injuries in kidneys of WT mice. Despite increased renal expression of lcn2 and urinary excretion of lipocalin-2, mice with selective deletion of lcn2 alleles in adipose tissue (Adipo-LKO) are protected from ANS- or aldosterone-induced renal injuries. By contrast, selective deletion of lcn2 alleles in kidney did not prevent aldosterone- or ANS-induced renal injuries. Transplantation of fat pads from WT donors increased the sensitivity of mice with complete deletion of Lcn2 alleles (LKO) to aldosterone-induced renal injuries. Aldosterone promoted the urinary excretion of a human lipocalin-2 variant, R81E, in turn causing renal injuries in LKO mice. Chronic treatment with R81E triggered significant renal injuries in LKO, resembling those observed in WT mice following ANS challenge. Taken in conjunction, the present results demonstrate that lipocalin-2 derived from adipose tissue causes acute and chronic renal injuries, largely independent of local lcn2 expression in kidney.
Authors
Wai Yan Sun, Bo Bai, Cuiting Luo, Kangmin Yang, Dahui Li, Donghai Wu, Michel Félétou, Nicole Villeneuve, Yang Zhou, Junwei Yang, Aimin Xu, Paul M. Vanhoutte, Yu Wang
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Poorly controlled diabetes leads to comorbidities and enhanced susceptibility to infections. While the immune components involved in wound healing in diabetes have been studied, the components involved in susceptibility to skin infections remain unclear. Here, we examined the effects of the inflammatory lipid mediator leukotriene B4 (LTB4) signaling through its receptor B leukotriene receptor 1 (BLT1) in the progression of methicillin-resistant Staphylococcus aureus (MRSA) skin infection in 2 models of diabetes. Diabetic mice produced higher levels of LTB4 in the skin, which correlated with larger nonhealing lesion areas and increased bacterial loads compared with nondiabetic mice. High LTB4 levels were also associated with dysregulated cytokine and chemokine production, excessive neutrophil migration but impaired abscess formation, and uncontrolled collagen deposition. Both genetic deletion and topical pharmacological BLT1 antagonism restored inflammatory response and abscess formation, followed by a reduction in the bacterial load and lesion area in the diabetic mice. Macrophage depletion in diabetic mice limited LTB4 production and improved abscess architecture and skin host defense. These data demonstrate that exaggerated LTB4/BLT1 responses mediate a derailed inflammatory milieu that underlies poor host defense in diabetes. Prevention of LTB4 production/actions could provide a new therapeutic strategy to restore host defense in diabetes.
Authors
Stephanie L. Brandt, Sue Wang, Naiara N. Dejani, Nathan Klopfenstein, Seth Winfree, Luciano Filgueiras, Brian P. McCarthy, Paul R. Territo, C. Henrique Serezani
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Organ transplant recipients (OTRs) on cyclosporine A (CSA) are prone to catastrophic cutaneous squamous cell carcinoma (SCC). Allograft-sparing, cancer-targeting systemic treatments are unavailable. We have shown increased risk for catastrophic SCC in OTRs via CSA-mediated induction of IL-22. Herein, we found that CSA drives SCC proliferation and tumor growth through IL-22 and JAK/STAT pathway induction. We in turn inhibited SCC growth with an FDA-approved JAK1/2 inhibitor, ruxolitinib. In human SCC cells, the greatest proliferative response to IL-22 and CSA treatment occurred in nonmetastasizing lines. IL-22 treatment upregulated JAK1 and STAT1/3 in A431 SCC cells. JAK/STAT pathway genes were highly expressed in tumors from a cohort of CSA-exposed OTRs and in SCC with high risk for metastasis. Compared with immunocompetent SCC, genes associated with innate immunity, response to DNA damage, and p53 regulation were differentially expressed in SCC from OTRs. In nude mice engrafted with human A431 cells, IL-22 and CSA treatment increased tumor growth and upregulated IL-22 receptor, JAK1, and STAT1/3 expression. Ruxolitinib treatment significantly reduced tumor volume and reversed the accelerated tumor growth. CSA and IL-22 exacerbate aggressive behavior in SCC. Targeting the IL-22 axis via selective JAK/STAT inhibition may reduce the progression of aggressive SCC in OTRs, without compromising immunosuppression.
Authors
Melody Abikhair Burgo, Nazanin Roudiani, Jie Chen, Alexis L. Santana, Nicole Doudican, Charlotte Proby, Diane Felsen, John A. Carucci
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Advanced age-related macular degeneration (AMD), the leading cause of blindness among people over 50 years of age, is characterized by atrophic neurodegeneration or pathologic angiogenesis. Early AMD is characterized by extracellular cholesterol-rich deposits underneath the retinal pigment epithelium (RPE) called drusen or in the subretinal space called subretinal drusenoid deposits (SDD) that drive disease progression. However, mechanisms of drusen and SDD biogenesis remain poorly understood. Although human AMD is characterized by abnormalities in cholesterol homeostasis and shares phenotypic features with atherosclerosis, it is unclear whether systemic immunity or local tissue metabolism regulates this homeostasis. Here, we demonstrate that targeted deletion of macrophage cholesterol ABC transporters A1 (ABCA1) and -G1 (ABCG1) leads to age-associated extracellular cholesterol-rich deposits underneath the neurosensory retina similar to SDD seen in early human AMD. These mice also develop impaired dark adaptation, a cardinal feature of RPE cell dysfunction seen in human AMD patients even before central vision is affected. Subretinal deposits in these mice progressively worsen with age, with concomitant accumulation of cholesterol metabolites including several oxysterols and cholesterol esters causing lipotoxicity that manifests as photoreceptor dysfunction and neurodegeneration. These findings suggest that impaired macrophage cholesterol transport initiates several key elements of early human AMD, demonstrating the importance of systemic immunity and aging in promoting disease manifestation. Polymorphisms in genes involved with cholesterol transport and homeostasis are associated with a significantly higher risk of developing AMD, thus making these studies translationally relevant by identifying potential targets for therapy.
Authors
Norimitsu Ban, Tae Jun Lee, Abdoulaye Sene, Mayur Choudhary, Michael Lekwuwa, Zhenyu Dong, Andrea Santeford, Jonathan B. Lin, Goldis Malek, Daniel S. Ory, Rajendra S. Apte
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The respiratory tract is normally kept essentially free of bacteria by cilia-mediated mucus transport, but in chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF), bacteria and mucus accumulates instead. To address the mechanisms behind the mucus accumulation, the proteome of bronchoalveolar lavages from COPD patients and mucus collected in an elastase-induced mouse model of COPD was analyzed, revealing similarities with each other and with the protein content in colonic mucus. Moreover, stratified laminated sheets of mucus were observed in airways from patients with CF and COPD and in elastase-exposed mice. On the other hand, the mucus accumulation in the elastase model was reduced in Muc5b-KO mice. While mucus plugs were removed from airways by washing with hypertonic saline in the elastase model, mucus remained adherent to epithelial cells. Bacteria were trapped on this mucus, whereas, in non–elastase-treated mice, bacteria were found on the epithelial cells. We propose that the adherence of mucus to epithelial cells observed in CF, COPD, and the elastase-induced mouse model of COPD separates bacteria from the surface cells and, thus, protects the respiratory epithelium.
Authors
Joan Antoni Fernández-Blanco, Dalia Fakih, Liisa Arike, Ana M. Rodríguez-Piñeiro, Beatriz Martínez-Abad, Elin Skansebo, Sonya Jackson, James Root, Dave Singh, Christopher McCrae, Christopher M. Evans, Annika Åstrand, Anna Ermund, Gunnar C. Hansson
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Sarcomas are still unsolved therapeutic challenges. Cancer stem cells are believed to contribute to sarcoma development, but lack of specific markers prevents their characterization and targeting. Here, we show that calpain-6 expression is associated with cancer stem cell features. In mouse models of bone sarcoma, calpain-6–expressing cells have unique tumor-initiating and metastatic capacities. Calpain-6 levels are especially high in tumors that have been successfully propagated in mouse to establish patient-derived xenografts. We found that calpain-6 levels are increased by hypoxia in vitro and calpain-6 is detected within hypoxic areas in tumors. Furthermore, calpain-6 expression depends on the stem cell transcription network that involves Oct4, Nanog, and Sox2 and is activated by hypoxia. Calpain-6 knockdown blocks tumor development in mouse and induces depletion of the cancer stem cell population. Data from transcriptomic analyses reveal that calpain-6 expression in sarcomas inversely correlates with senescence markers. Calpain-6 knockdown suppresses hypoxia-dependent prevention of senescence entry and also promotion of autophagic flux. Together, our results demonstrate that calpain-6 identifies sarcoma cells with stem-like properties and is a mediator of hypoxia to prevent senescence, promote autophagy, and maintain the tumor-initiating cell population. These findings open what we believe is a novel therapeutic avenue for targeting sarcoma stem cells.
Authors
Caroline Andrique, Laetitia Morardet, Laetitia K. Linares, Madi Y. Cissé, Candice Merle, Frédéric Chibon, Sylvain Provot, Eric Haÿ, Hang-Korng Ea, Martine Cohen-Solal, Dominique Modrowski
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BACKGROUND. Plasma lipidomic measures may enable improved prediction of cardiovascular outcomes in secondary prevention. The aim of this study is to determine the association of plasma lipidomic measurements with cardiovascular events and assess their potential to predict such events. METHODS. Plasma lipids (n = 342) were measured in a retrospective subcohort (n = 5,991) of the LIPID study. Proportional hazards regression was used to identify lipids associated with future cardiovascular events (nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death) and cardiovascular death. Multivariable models adding lipid species to traditional risk factors were created using lipid ranking established from the Akaike information criterion within a 5-fold cross-validation framework. The results were tested on a diabetic case cohort from the ADVANCE study (n = 3,779). RESULTS. Specific ceramide species, sphingolipids, phospholipids, and neutral lipids containing omega-6 fatty acids or odd-chain fatty acids were associated with future cardiovascular events (106 species) and cardiovascular death (139 species). The addition of 7 lipid species to a base model (11 conventional risk factors) resulted in an increase in the C-statistics from 0.629 (95% CI, 0.628–0.630) to 0.654 (95% CI, 0.653–0.656) for prediction of cardiovascular events and from 0.673 (95% CI, 0.671–0.675) to 0.727 (95% CI, 0.725–0.728) for prediction of cardiovascular death. Categorical net reclassification improvements for cardiovascular events and cardiovascular death were 0.083 (95% CI, 0.081–0.086) and 0.166 (95% CI, 0.162–0.170), respectively. Evaluation on the ADVANCE case cohort demonstrated significant improvement on the base models. CONCLUSIONS. The improvement in the prediction of cardiovascular outcomes, above conventional risk factors, demonstrates the potential of plasma lipidomic profiles as biomarkers for cardiovascular risk stratification in secondary prevention. FUNDING. Bristol-Myers Squibb, the National Health and Medical Research Council of Australia (grants 211086, 358395, and 1029754), and the Operational Infrastructure Support Program of the Victorian government of Australia.
Authors
Piyushkumar A. Mundra, Christopher K. Barlow, Paul J. Nestel, Elizabeth H. Barnes, Adrienne Kirby, Peter Thompson, David R. Sullivan, Zahir H. Alshehry, Natalie A. Mellett, Kevin Huynh, Kaushala S. Jayawardana, Corey Giles, Malcolm J. McConville, Sophia Zoungas, Graham S. Hillis, John Chalmers, Mark Woodward, Gerard Wong, Bronwyn A. Kingwell, John Simes, Andrew M. Tonkin, Peter J. Meikle, LIPID Study Investigators
×Abstract
Although initially responsive to androgen signaling inhibitors (ASIs), metastatic castration-resistant prostate cancer (mCRPC) inevitably develops and is incurable. In addition to adenocarcinoma (adeno), neuroendocrine prostate cancer (NEPC) emerges to confer ASI resistance. We have previously combined laser capture microdissection and phage antibody display library selection on human cancer specimens and identified novel internalizing antibodies binding to tumor cells residing in their tissue microenvironment. We identified the target antigen for one of these antibodies as CD46, a multifunctional protein that is best known for negatively regulating the innate immune system. CD46 is overexpressed in primary tumor tissue and CRPC (localized and metastatic; adeno and NEPC), but expressed at low levels on normal tissues except for placental trophoblasts and prostate epithelium. Abiraterone- and enzalutamide-treated mCRPC cells upregulate cell surface CD46 expression. Genomic analysis showed that the CD46 gene is gained in 45% abiraterone-resistant mCRPC patients. We conjugated a tubulin inhibitor to our macropinocytosing anti-CD46 antibody and showed that the resulting antibody-drug conjugate (ADC) potently and selectively kills both adeno and NEPC cell lines in vitro (sub-nM EC50) but not normal cells. CD46 ADC regressed and eliminated an mCRPC cell line xenograft in vivo in both subcutaneous and intrafemoral models. Exploratory toxicology studies of the CD46 ADC in non-human primates demonstrated an acceptable safety profile. Thus, CD46 is an excellent target for antibody-based therapy development, which has potential to be applicable to both adenocarcinoma and neuroendocrine types of mCRPC that are resistant to current treatment.
Authors
Yang Su, Yue Liu, Christopher R. Behrens, Scott Bidlingmaier, Nam-Kyung Lee, Rahul Aggarwal, Daniel W. Sherbenou, Alma L. Burlingame, Byron C. Hann, Jeffry P. Simko, Gayatri Premasekharan, Pamela L. Paris, Marc A. Shuman, Youngho Seo, Eric J. Small, Bin Liu
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Noninvasive imaging of visual system components in vivo is critical for understanding the causal mechanisms of retinal diseases and for developing therapies for their treatment. However, ultraviolet light needed to excite endogenous fluorophores that participate in metabolic processes of the retina is highly attenuated by the anterior segment of the human eye. In contrast, 2-photon excitation fluorescence imaging with pulsed infrared light overcomes this obstacle. Reducing retinal exposure to laser radiation remains a major barrier in advancing this technology to studies in humans. To increase fluorescence intensity and reduce the requisite laser power, we modulated ultrashort laser pulses with high-order dispersion compensation and applied sensorless adaptive optics and custom image recovery software and observed an over 300% increase in fluorescence of endogenous retinal fluorophores when laser pulses were shortened from 75 fs to 20 fs. No functional or structural changes to the retina were detected after exposure to 2-photon excitation imaging light with 20-fs pulses. Moreover, wide bandwidth associated with short pulses enables excitation of multiple fluorophores with different absorption spectra and thus can provide information about their relative changes and intracellular distribution. These data constitute a substantial advancement for safe 2-photon fluorescence imaging of the human eye.
Authors
Grazyna Palczewska, Patrycjusz Stremplewski, Susie Suh, Nathan Alexander, David Salom, Zhiqian Dong, Daniel Ruminski, Elliot H. Choi, Avery E. Sears, Timothy S. Kern, Maciej Wojtkowski, Krzysztof Palczewski
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Bacterial biofilm infections of implantable medical devices decrease the effectiveness of antibiotics, creating difficult-to-treat chronic infections. Prosthetic joint infections (PJI) are particularly problematic because they require prolonged antibiotic courses and reoperations to remove and replace the infected prostheses. Current models to study PJI focus on Gram-positive bacteria, but Gram-negative PJI (GN-PJI) are increasingly common and are often more difficult to treat, with worse clinical outcomes. Herein, we sought to develop a mouse model of GN-PJI to investigate the pathogenesis of these infections and identify potential therapeutic targets. An orthopedic-grade titanium implant was surgically placed in the femurs of mice, followed by infection of the knee joint with Pseudomonas aeruginosa or Escherichia coli. We found that in vitro biofilm-producing activity was associated with the development of an in vivo orthopedic implant infection characterized by bacterial infection of the bone/joint tissue, biofilm formation on the implants, reactive bone changes, and inflammatory immune cell infiltrates. In addition, a bispecific antibody targeting P. aeruginosa virulence factors (PcrV and Psl exopolysaccharide) reduced the bacterial burden in vivo. Taken together, our findings provide a preclinical model of GN-PJI and suggest the therapeutic potential of targeting biofilm-associated antigens.
Authors
John M. Thompson, Robert J. Miller, Alyssa G. Ashbaugh, Carly A. Dillen, Julie E. Pickett, Yu Wang, Roger V. Ortines, Robert S. Sterling, Kevin P. Francis, Nicholas M. Bernthal, Taylor S. Cohen, Christine Tkaczyk, Li Yu, C. Kendall Stover, Antonio DiGiandomenico, Bret R. Sellman, Daniel L.J. Thorek, Lloyd S. Miller
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BACKGROUND. The extent of weight loss among patients undergoing bariatric surgery is highly variable. Herein, we tested the contribution of genetic background to such interindividual variability after biliopancreatic diversion with duodenal switch. METHODS. Percentage of excess body weight loss (%EBWL) was monitored in 865 patients over a period of 48 months after bariatric surgery, and two polygenic risk scores were constructed with 186 and 11 (PRS186 and PRS11) single nucleotide polymorphisms previously associated with body mass index (BMI). RESULTS. The accuracy of the %EBWL logistic prediction model — including initial BMI, age, sex, and surgery modality, and assessed as the area under the receiver operating characteristics (ROC) curve adjusted for optimism (AUCadj = 0.867) — significantly increased after the inclusion of PRS186 (ΔAUCadj = 0.021; 95% CI of the difference [95% CIdiff] = 0.005–0.038) but not PRS11 (ΔAUCadj= 0.008; 95% CIdiff= –0.003–0.019). The overall fit of the longitudinal linear mixed model for %EBWL showed a significant increase after addition of PRS186 (–2 log-likelihood = 12.3; P = 0.002) and PRS11 (–2 log-likelihood = 9.9; P = 0.007). A significant interaction with postsurgery time was found for PRS186 (β = –0.003; P = 0.008) and PRS11 (β = –0.008; P = 0.03). The inclusion of PRS186 and PRS11 in the model improved the cost-effectiveness of bariatric surgery by reducing the percentage of false negatives from 20.4% to 10.9% and 10.2%, respectively. CONCLUSION. These results revealed that genetic background has a significant impact on weight loss after biliopancreatic diversion with duodenal switch. Likewise, the improvement in weight loss prediction after addition of polygenic risk scores is cost-effective, suggesting that genetic testing could potentially be used in the presurgical assessment of patients with severe obesity. FUNDING. Heart and Stroke Foundation of Canada (G-17-0016627) and Canada Research Chair in Genomics Applied to Nutrition and Metabolic Health (no. 950-231-580).
Authors
Juan de Toro-Martín, Frédéric Guénard, André Tchernof, Louis Pérusse, Simon Marceau, Marie-Claude Vohl
×Abstract
Studies in patients with genetic defects can provide unique insights regarding the role of specific genes and pathways in humans. Patients with defects in the Th17/IL-17 axis, such as patients harboring loss-of-function STAT3 mutations (autosomal-dominant hyper IgE syndrome; AD-HIES) present with recurrent oral fungal infections. Our studies aimed to comprehensively evaluate consequences of STAT3 deficiency on the oral commensal microbiome. We characterized fungal and bacterial communities in AD-HIES in the presence and absence of oral fungal infection compared with healthy volunteers. Analyses of oral mucosal fungal communities in AD-HIES revealed severe dysbiosis with dominance of Candida albicans (C. albicans) in actively infected patients and minimal representation of health-associated fungi and/or opportunists. Bacterial communities also displayed dysbiosis in AD-HIES, particularly in the setting of active Candida infection. Active candidiasis was associated with decreased microbial diversity and enrichment of the streptococci Streptococcus oralis (S. oralis) and S. mutans, suggesting an interkingdom interaction of C. albicans with oral streptococci. Increased abundance of S. mutans was consistent with susceptibility to dental caries in AD-HIES. Collectively, our findings illustrate a critical role for STAT3/Th17 in the containment of C. albicans as a commensal organism and an overall contribution in the establishment of fungal and bacterial oral commensal communities.
Authors
Loreto Abusleme, Patricia I. Diaz, Alexandra F. Freeman, Teresa Greenwell-Wild, Laurie Brenchley, Jigar V. Desai, Weng-Ian Ng, Steven M. Holland, Michail S. Lionakis, Julia A. Segre, Heidi H. Kong, Niki M. Moutsopoulos
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Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease causing fibrotic remodeling of the peripheral lung, leading to respiratory failure. Peripheral pulmonary epithelial cells lose normal alveolar epithelial gene expression patterns and variably express genes associated with diverse conducting airway epithelial cells, including basal cells. Single-cell RNA sequencing of pulmonary epithelial cells isolated from IPF lung tissue demonstrated altered expression of LncRNAs, including increased MEG3. MEG3 RNA was highly expressed in subsets of the atypical IPF epithelial cells and correlated with conducting airway epithelial gene expression patterns. Expression of MEG3 in human pulmonary epithelial cell lines increased basal cell–associated RNAs, including TP63, KRT14, STAT3, and YAP1, and enhanced cell migration, consistent with a role for MEG3 in regulating basal cell identity. MEG3 reduced expression of TP73, SOX2, and Notch-associated RNAs HES1 and HEY1, in primary human bronchial epithelial cells, demonstrating a role for MEG3 in the inhibition of genes influencing basal cell differentiation into club, ciliated, or goblet cells. MEG3 induced basal cell genes and suppressed genes associated with terminal differentiation of airway cells, supporting a role for MEG3 in regulation of basal progenitor cell functions, which may contribute to tissue remodeling in IPF.
Authors
Jason J. Gokey, John Snowball, Anusha Sridharan, Joseph P. Speth, Katharine E. Black, Lida P. Hariri, Anne-Karina T. Perl, Yan Xu, Jeffrey A. Whitsett
×Abstract
Belimumab has therapeutic benefit in active systemic lupus erythematosus (SLE), especially in patients with high-titer anti-dsDNA antibodies. We asked whether the profound B cell loss in belimumab-treated SLE patients is accompanied by shifts in the immunoglobulin repertoire. We enrolled 15 patients who had been continuously treated with belimumab for more than 7 years, 17 matched controls, and 5 patients who were studied before and after drug initiation. VH genes of sort-purified mature B cells and plasmablasts were subjected to next-generation sequencing. We found that B cell–activating factor (BAFF) regulates the transitional B cell checkpoint, with conservation of transitional 1 (T1) cells and approximately 90% loss of T3 and naive B cells after chronic belimumab treatment. Class-switched memory B cells, B1 B cells, and plasmablasts were also substantially depleted. Next-generation sequencing revealed no redistribution of VH, DH, or JH family usage and no effect of belimumab on representation of the autoreactive VH4-34 gene or CDR3 composition in unmutated IgM sequences, suggesting a minimal effect on selection of the naive B cell repertoire. Interestingly, a significantly greater loss of VH4-34 was observed among mutated IgM and plasmablast sequences in chronic belimumab–treated subjects than in controls, suggesting that belimumab promotes negative selection of activated autoreactive B cells.
Authors
Weiqing Huang, Tam D. Quach, Cosmin Dascalu, Zheng Liu, Tungming Leung, Miranda Byrne-Steele, Wenjing Pan, Qunying Yang, Jian Han, Martin Lesser, Thomas L. Rothstein, Richard Furie, Meggan Mackay, Cynthia Aranow, Anne Davidson
×Abstract
Offspring of women with gestational diabetes mellitus (GDM) are at increased risk of developing metabolic disease, potentially mediated by epigenetic mechanisms. We recruited 608 GDM and 626 control offspring from the Danish National Birth Cohort, aged between 9 and 16 years. DNA methylation profiles were measured in peripheral blood of 93 GDM offspring and 95 controls using the Illumina HumanMethylation450 BeadChip. Pyrosequencing was performed for validation/replication of putative GDM-associated, differentially methylated CpGs in additional 905 offspring (462 GDM, 444 control offspring). We identified 76 differentially methylated CpGs in GDM offspring compared with controls in the discovery cohort (FDR, P < 0.05). Adjusting for offspring BMI did not affect the association between methylation levels and GDM status for any of the 76 CpGs. Most of these epigenetic changes were due to confounding by maternal prepregnancy BMI; however, 13 methylation changes were independently associated with maternal GDM. Three prepregnancy BMI–associated CpGs (cg00992687 and cg09452568 of ESM1 and cg14328641 of MS4A3) were validated in the replication cohort, while cg09109411 (PDE6A) was found to be associated with GDM status. The identified methylation changes may reflect developmental programming of organ disease mechanisms and/or may serve as disease biomarkers.
Authors
Line Hjort, David Martino, Louise Groth Grunnet, Haroon Naeem, Jovana Maksimovic, Anders Henrik Olsson, Cuilin Zhang, Charlotte Ling, Sjurdur Frodi Olsen, Richard Saffery, Allan Arthur Vaag
×Abstract
While it has been recognized that human papillomavirus–associated (HPV-associated) oropharyngeal cancer (OPC) portends an improved prognosis, distinct patterns of disease recurrence have emerged. Molecular characterization of this subset of HPV patients remains unexplored. We evaluated 52 metastatic HPV+ OPC patients from our institution and paired massively parallel sequencing data with clinical parameters and survival outcomes in 81% of patients. Genomic data were then compared with 2 molecularly defined, curable HPV+ cohorts. Metastatic HPV+ OPC patients with pulmonary-only metastases demonstrated worse outcomes. Nonexclusive somatic alterations in KMT2D and PIK3CA were most frequent, with PRKDC alterations occurring at higher frequency when compared with all sequenced HPV+ OPC patients. PI3K pathway alterations were associated with improved outcomes among metastatic HPV+ OPC patients. We demonstrate subtle differences in the mutational landscape between curable and metastatic HPV+ OPC populations, with a trend towards more frequent DNA repair protein alterations in the latter. We demonstrate improved outcomes when PI3K pathway alterations are present in these patients. We provide molecular insights for this important HPV+ subgroup that have significant therapeutic implications.
Authors
Glenn J. Hanna, Alec Kacew, Nicole G. Chau, Priyanka Shivdasani, Jochen H. Lorch, Ravindra Uppaluri, Robert I. Haddad, Laura E. MacConaill
×Abstract
When obesity is caused by consumption of a high-fat diet, the tumor suppressor pRb is phosphoinactivated in the neurons of the mediobasal hypothalamus, a brain area critical for energy-balance regulation. However, the functional relevance of pRb phosphoinactivation in the mediobasal hypothalamus to diet-induced obesity remains unknown. Here, we show that inhibiting pRb phosphorylation in the mediobasal hypothalamus can prevent and treat diet-induced obesity in mice. Expressing an unphosphorylable pRb nonselectively in the mediobasal hypothalamus or conditionally in anorexigenic POMC neurons inhibits diet-induced obesity. Intracerebroventricular delivery of US Food and Drug Administration–approved (FDA-approved) cyclin-dependent kinase 4 (CDK4) inhibitor abemaciclib inhibits pRb phosphorylation in the mediobasal hypothalamus and prevents diet-induced obesity. Oral administration of abemaciclib at doses approved for human use reduces fat mass in diet-induced obese mice by increasing lipid oxidation without significantly reducing lean mass. With analysis of recent literature identifying CDK4 as the most abundantly expressed neuronal CDK in the mediobasal hypothalamus, our work uncovers CDK4 as the major kinase for hypothalamic pRb phosphoinactivation and a highly effective central antiobesity target. As three CDK4/6 inhibitors have recently received FDA approval for life-long breast cancer therapy, our study provides a preclinical basis for their expedient repurposing for obesity management.
Authors
Niloy Jafar Iqbal, Zhonglei Lu, Shun Mei Liu, Gary J. Schwartz, Streamson Chua Jr., Liang Zhu
×Abstract
Pneumonia represents the leading infectious cause of death in the United States. Foxp3+ regulatory T cells promote recovery from severe pneumonia in mice, but T cell responses in patients with pneumonia remain incompletely characterized because of the limited ability to serially sample the distal airspaces and perform multidimensional molecular assessments on the small numbers of recovered cells. As T cell function is governed by their transcriptional and epigenetic landscape, we developed a method to safely perform high-resolution transcriptional and DNA methylation profiling of T cell subsets from the alveoli of critically ill patients. Our method involves nonbronchoscopic bronchoalveolar lavage combined with multiparameter fluorescence-activated cell sorting, unsupervised low-input RNA-sequencing, and a modified reduced-representation bisulfite sequencing protocol. Here, we demonstrate the safety and feasibility of our method and use it to validate functional genomic elements that were predicted by mouse models. Because of its potential for widespread application, our techniques allow unprecedented insights into the biology of human pneumonia.
Authors
James M. Walter, Kathryn A. Helmin, Hiam Abdala-Valencia, Richard G. Wunderink, Benjamin D. Singer
×Abstract
Invariant natural killer T (iNKT) cells are activated at sites of local tissue injury, or globally during vaso-occlusive episodes of sickle cell disease (SCD). Tissue damage stimulates production of CD1d-restricted lipid antigens that activate iNKT cells to produce Th1- and Th2-type cytokines. Here, we show that circulating iNKT cells in SCD patients express elevated levels of the ectonucleoside triphosphate diphosphosphohydrolase, CD39, as well the adenosine A2A receptor (A2AR). We also investigated the effects of stimulating cultured human iNKT cells on the expression of genes involved in the regulation of purinergic signaling. iNKT cell stimulation caused induction of ADORA2A, P2RX7, CD38, CD39, ENPP1, CD73, PANX1, and ENT1. Transcription of ADA, which degrades adenosine, was reduced. Induction of CD39 mRNA was associated with increased ecto-ATPase activity on iNKT cells that was blocked by POM1. Exposure of iNKT cells to A2AR agonists during stimulation reduced production of IFN-γ and enhanced production of IL-13 and CD39. Based on these findings, we define “purinergic Th2-type cytokine bias” as an antiinflammatory purinergic response to iNKT cell stimulation resulting from changes in the transcription of several genes involved in purine release, extracellular metabolism, and signaling.
Authors
Jennifer C. Yu, Gene Lin, Joshua J. Field, Joel Linden
×Abstract
An indispensable role of macrophages in bone repair has been well recognized. Previous data have demonstrated the copresence of M1 macrophages and mesenchymal stem cells (MSCs) during the proinflammatory stage of bone repair. However, the exact role of M1 macrophages in MSC function and bone repair is unknown. This study aimed to define the role of M1 macrophages at bone injury sites via the function of 1,25-Dihydroxyvitamin D (1,25[OH]2D) in suppressing M1 but promoting M2 differentiation. We showed that 1,25(OH)2D suppressed M1 macrophage–mediated enhancement of MSC migration. Additionally, 1,25(OH)2D inhibited M1 macrophage secretion of osteogenic proteins (i.e., Oncostatin M, TNF-α, and IL-6). Importantly, the 1,25(OH)2D-mediated suppression of osteogenic function in M1 macrophages at the proinflammatory stage was associated with 1,25(OH)2D-mediated reduction of MSC abundance, compromised osteogenic potential of MSCs, and impairment of fracture repair. Furthermore, outside the proinflammatory stage, 1,25(OH)2D treatment did not suppress fracture repair. Accordingly, our data support 2 conclusions: (a) M1 macrophages are important for the recruitment and osteogenic priming of MSCs and, hence, are necessary for fracture repair, and (b) under vitamin D–sufficient conditions, 1,25(OH)2D treatment is unnecessary and can be detrimental if provided during the proinflammatory stage of fracture healing.
Authors
Samiksha Wasnik, Charles H. Rundle, David J. Baylink, Mohammad Safaie Yazdi, Edmundo E. Carreon, Yi Xu, Xuezhong Qin, Kin-Hing William Lau, Xiaolei Tang
×Abstract
Adult polyglucosan body disease (APBD) is a late-onset disease caused by intracellular accumulation of polyglucosan bodies, formed due to glycogen-branching enzyme (GBE) deficiency. To find a treatment for APBD, we screened 1,700 FDA-approved compounds in fibroblasts derived from APBD-modeling GBE1-knockin mice. Capitalizing on fluorescent periodic acid–Schiff reagent, which interacts with polyglucosans in the cell, this screen discovered that the flavoring agent guaiacol can lower polyglucosans, a result also confirmed in APBD patient fibroblasts. Biochemical assays showed that guaiacol lowers basal and glucose 6-phosphate–stimulated glycogen synthase (GYS) activity. Guaiacol also increased inactivating GYS1 phosphorylation and phosphorylation of the master activator of catabolism, AMP-dependent protein kinase. Guaiacol treatment in the APBD mouse model rescued grip strength and shorter lifespan. These treatments had no adverse effects except making the mice slightly hyperglycemic, possibly due to the reduced liver glycogen levels. In addition, treatment corrected penile prolapse in aged GBE1-knockin mice. Guaiacol’s curative effects can be explained by its reduction of polyglucosans in peripheral nerve, liver, and heart, despite a short half-life of up to 60 minutes in most tissues. Our results form the basis to use guaiacol as a treatment and prepare for the clinical trials in APBD.
Authors
Or Kakhlon, Igor Ferreira, Leonardo J. Solmesky, Netaly Khazanov, Alexander Lossos, Rafael Alvarez, Deniz Yetil, Sergey Pampou, Miguel Weil, Hanoch Senderowitz, Pablo Escriba, Wyatt W. Yue, H. Orhan Akman
