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Abstract
Systemic sclerosis (SSc) is a heterogeneous autoimmune disorder that results in skin fibrosis, autoantibody production and internal organ dysfunction. We previously identified four ‘intrinsic’ subsets of SSc based upon skin gene expression that are found across organ systems. Gene expression regulators that underlie the SSc intrinsic subsets, or are associated with clinical covariates, have not been systematically characterized. Here we present a computational framework to calculate the activity scores of gene expression regulators and identify their associations with SSc clinical outcomes. We find regulator activity scores can reproduce the intrinsic molecular subsets with distinct sets of regulators identified for inflammatory, fibroproliferative and normal-like samples. Regulators most highly correlated with modified Rodnan skin score (MRSS) also varied by intrinsic subset. We identify a subgroup of fibroproliferative/inflammatory SSc patients with more severe pathophenotypes. We further identify a subgroup of SSc patients that had higher MRSS and increased likelihood of interstitial lung disease. Using an independent cohort, we show this group was most likely to show forced vital capacity decline over a period of 36 – 54 months. Our results demonstrate an association between the activation of regulators, gene expression subsets and clinical variables that can identify SSc patients with more severe disease.
Authors
Yue Wang, Jennifer M. Franks, Monica Yang, Diana M. Toledo, Tammara A. Wood, Monique Hinchcliff, Michael L. Whitfield
Abstract
Purpose: There is a rapidly evolving portfolio of immune therapeutic modulators, but the relative incidence of immune targets in human gliomas is unknown. In order to prioritize available immune therapeutics, immune profiling across glioma grades was conducted followed by preclinical determinations of therapeutic effect in immune competent mice harboring gliomas. Methods: CD4+ and CD8+ T cells and CD11b+ myeloid cells were isolated from the blood of healthy donors and the blood and tumors of newly diagnosed and recurrent glioma patients and profiled for the expression of immune modulatory targets with an available therapeutic. Preclinical murine models of glioma were used to assess therapeutic efficacy of agents targeting the most frequently expressed immune targets. Immune effector function was analyzed in the setting of glioma induced immune suppression. Results: In glioma patients, the adenosine-CD73-CD39 immune suppressive pathway was most frequently expressed, followed by PD-1. CD73 expression was upregulated on immune cells by 2-hydroxygluterate in IDH1 mutant glioma patients. In multiple murine glioma models, including those that express CD73, adenosine receptor inhibitors demonstrated a modest therapeutic response; however, the addition of other inhibitors of the adenosine pathway did not further enhance this therapeutic effect. Although adenosine receptor inhibitors could recover immunological effector functions in T cells after the engagement of this pathway, immune recovery was impaired in the presence of gliomas, indicating that irreversible immune exhaustion limits the effectiveness of inhibitors of the adenosine pathway in glioma patients. Conclusions: This study illustrates vetting steps that should be considered prior to clinical trial implementation for immunotherapy resistant cancers including testing an agents ability to restore immunological function in the context of intended use.
Authors
Martina Ott, Karl-Heinz Tomaszowski, Anantha Marisetty, Ling-Yuan Kong, Jun Wei, Maya Duna, Katia Blumberg, Xiaorong Ji, Carmen B Jacobs, Gregory N. Fuller, Lauren A. Langford, Jason T. Huse, James P. Long, Jian Hu, Shulin Li, Jeffrey S. Weinberg, Sujit Prabhu, Raymond Sawaya, Sherise D. Ferguson, Ganesh Rao, Frederick F. Lang, Michael A. Curran, Amy B. Heimberger
Abstract
Background: Elevated levels of inflammatory cytokines have been associated with poor outcomes among COVID-19 patients. It is unknown, however, how these levels compare to those observed in critically ill patients with ARDS or sepsis due to other causes. Methods: We used a luminex assay to determine expression of 76 cytokines from plasma of hospitalized COVID-19 patients and banked plasma samples from ARDS and sepsis patients. Our analysis focused on detecting statistical differences in levels of 6 cytokines associated with cytokine storm (IL-1b, IL-1RA, IL-6, IL-8, IL-18, and TNFα) between patients with moderate COVID-19, severe COVID-19, and ARDS or sepsis. Results: 15 hospitalized COVID-19 patients, 9 of whom were critically ill, were compared to critically ill patients with ARDS (n = 12) or sepsis (n = 16). There were no statistically significant differences in baseline levels of IL-1b, IL-1RA, IL-6, IL-8, IL-18, and TNFα between patients with COVID-19 and critically ill controls with ARDS or sepsis. Conclusions: Levels of inflammatory cytokines were not higher in severe COVID-19 patients than in moderate COVID-19 or critically ill patients with ARDS or sepsis in this small cohort. Broad use of immunosuppressive therapies in ARDS has failed in numerous Phase 3 studies; use of these therapies in unselected patients with COVID-19 may be unwarranted. Funding: A.J.R.: Stanford ICU Biobank NHLBI K23 HL125663. C.A.B.: Burroughs Wellcome Fund Investigators in the Pathogenesis of Infectious Diseases #1016687; NIH/NIAID U19AI057229-16 (PI MM Davis); Stanford Maternal Child Health Research Institute; Chan Zuckerberg Biohub.
Authors
Jennifer G. Wilson, Laura J. Simpson, Anne-Maud Ferreira, Arjun Rustagi, Jonasel A. Roque, Adijat Asuni, Thanmayi Ranganath, Philip M. Grant, Aruna K. Subramanian, Yael Rosenberg-Hasson, Holden Maecker, Susan Holmes, Joseph E. Levitt, Catherine Blish, Angela J. Rogers
Abstract
Using the global Hipk2-null mice in various models of kidney disease, we previously demonstrated the central role of homeodomain interacting protein kinase 2 (HIPK2) in the development of renal fibrosis. However, whether the renal tubular epithelial cell (RTEC)-specific HIPK2 function significantly contributed to renal fibrogenesis had not been established. Herein, using RTEC-specific HIPK2 null mice and transgenic mice with RTEC-specific overexpression of the wildtype (WT) or kinase-dead (KD) mutant of HIPK2, we now show that the modulation of tubular HIPK2 expression and activity can profoundly affect renal fibrosis development in vivo. The loss of HIPK2 expression in RTECs resulted in a marked diminution of renal fibrosis in mouse models of unilateral obstruction (UUO) and HIV-associated nephropathy (HIVAN) in Tg26 mice, which was associated with the reduction of Smad3 activation and downstream expression of profibrotic markers. Conversely, the overexpression of WT HIPK2 in RTECs accentuated the extent of renal fibrosis in the setting of UUO, HIVAN, and folic acid nephropathy (FAN) in mice. Importantly, the overexpression of HIPK2 KD mutant or administration of BT173, an allosteric inhibitor of HIPK2-Smad3 interaction, markedly attenuated the renal fibrosis in these mouse models of kidney disease, indicating that HIPK2 requires both the kinase activity and its interaction with Smad3 to promote TGF--mediated renal fibrosis. Together, these results establish an important RTEC-specific role of HIPK2 in kidney fibrosis and further substantiates the inhibition of HIPK2 as a therapeutic approach toward renal fibrosis.
Authors
Wenzhen Xiao, Jing E, Li Bao, Ying Fan, Yuanmeng Jin, Andrew Wang, David Bauman, Zhengzhe Li, Ya-Li Zheng, Ruijie Liu, Kyung Lee, John Cijiang He
Abstract
Orphan nuclear receptor estrogen-related receptor (ERR)γ stimulates bile acid production, however, the role and the regulatory mechanism of ERRγ in cholestatic liver disease are largely unknown. This study identifies that Sirt6 is a deacetylase of ERRγ and suggests a novel mechanism by which Sirt6 activation alleviates cholestatic liver damage and fibrosis through regulating ERRγ. We observed that hepatic expression of Sirt6 is repressed while that of ERRγ is upregulated in murine cholestasis models. Hepatocyte-specific Sirt6 knockout mice were more severely injured following a bile duct ligation (BDL) compared to wild-type mice and adenoviral re-expression of Sirt6 reversed liver damage and fibrosis as demonstrated by biochemical and histological analyses. Mechanistically, Sirt6 deacetylated ERRγ, thereby destabilized ERRγ and inhibited its transcriptional activity. Elimination of hepatic ERRγ using Ad-shERRγ abolished the deleterious effects of Sirt6 deficiency, while ERRγ overexpression aggravated cholestatic liver injury. Administration of a Sirt6 deacetylase activator prevented BDL-induced liver damage and fibrosis. In patients with cholestasis, Sirt6 expression was decreased while total- and acetylated-ERRγ levels were increased, confirming negative regulation of ERRγ by Sirt6. Thus, Sirt6 activation represents a new therapeutic strategy for treating cholestatic liver injury.
Authors
Lihua Hao, In Hyuk Bang, Jie Wang, Yuancheng Mao, Jae Do Yang, Soon-Young Na, Jeong Kon Seo, Hueng-Sik Choi, Eun Ju Bae, Byung-Hyun Park
Abstract
Aromatase inhibitors (AIs) reduce breast cancer recurrence and prolong survival, but up to 30% of patients exhibit recurrence. Using a genome-wide association study of patients entered on MA.27, a phase III randomized trial of anastrozole vs exemestane, we identified a SNP in CUB And Sushi Multiple Domains 1 (CSMD1) associated with breast cancer free interval, with the variant allele associated with fewer distant recurrences. Mechanistically, CSMD1 regulates CYP19 expression in a SNP-, and drug-dependent fashion and this regulation is different among three AIs, anastrozole, exemestane, and letrozole. Overexpression of CSMD1 sensitized AI-resistant cells to anastrozole but not to the other two AIs. The SNP in CSMD1 that was associated with increased CSMD1 and CYP19 expression levels increased anastrozole sensitivity, but not letrozole or exemestane sensitivity. Anastrozole degrades estrogen receptor α (ERα), especially in the presence of estradiol (E2). ER positive breast cancer organoids and AI- or fulvestrant-resistant breast cancer cells were more sensitive to anastrozole plus E2 than to AI alone. Our findings suggest that the CSMD1 SNP might help to predict AI response and anastrozole plus E2 serves as a potential new therapeutic strategy for patients with AI- or fulvestrant-resistant breast cancers.
Authors
Junmei Cairns, James N. Ingle, Tanda T. M. Dudenkov, Krishna R. Kalari, Erin E. Carlson, Jie Na, Aman U. Buzdar, Mark E. Robson, Matthew J. Ellis, Paul E. Goss, Lois E. Shepherd, Barbara Goodnature, Matthew P. Goetz, Richard M. Weinshilboum, Hu Li, Mehrab Ghanat Bari, Liewei Wang
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a common comorbidity among people living with HIV with a more aggressive course than in the general population. In a recent randomized placebo-controlled trial, we demonstrated that the growth hormone-releasing hormone analogue tesamorelin reduced liver fat and prevented fibrosis progression in HIV-associated NAFLD over one year. As such, tesamorelin is the first strategy that has shown to be effective against NAFLD among the HIV population. The current study leveraged paired liver biopsy specimens from this trial to identify hepatic gene pathways that are differentially modulated by tesamorelin versus placebo. Using Gene Set Enrichment Analysis (GSEA), we found that tesamorelin increased hepatic expression of hallmark gene sets involved in oxidative phosphorylation and decreased hepatic expression of gene sets contributing to inflammation, tissue repair, and cell division. Tesamorelin also reciprocally up- and downregulated curated gene sets associated with favorable and poor hepatocellular carcinoma prognosis, respectively. Notably, among tesamorelin-treated participants, these changes in hepatic expression correlated with improved fibrosis-related gene score. Our findings inform our knowledge of the biology of growth hormone action on the liver and provide a mechanistic basis for the observed clinical effects of tesamorelin on the liver.
Authors
Lindsay T. Fourman, James M. Billingsley, George Agyapong, Shannan J. Ho Sui, Meghan N. Feldpausch, Julia Purdy, Isabel Zheng, Chelsea S. Pan, Kathleen E. Corey, Martin Torriani, David E. Kleiner, Colleen M. Hadigan, Takara L. Stanley, Raymond T. Chung, Steven K. Grinspoon
Abstract
Current management of childhood leukemia is tailored based on disease risk determined by clinical features at presentation. Whether properties of the host immune response impact disease risk and outcome is not known. Here we combine mass cytometry, single cell genomics and functional studies to characterize the bone marrow immune environment in children with B-cell acute lymphoblastic leukemia, and acute myelogenous leukemia at presentation. T cells in leukemia marrow demonstrate evidence of chronic immune activation and exhaustion/dysfunction, with attrition of naïve T cells and TCF1+ stem-like memory T cells and accumulation of terminally-differentiated effector T cells. Marrow-infiltrating natural killer cells also exhibit evidence of dysfunction, particularly in myeloid leukemia. Properties of immune cells identified distinct immune phenotype-based clusters correlating with disease risk in acute lymphoblastic leukemia. High-risk immune signatures were associated with expression of stem-like genes on tumor cells. These data provide a comprehensive assessment of the immune landscape of childhood leukemias and identify targets potentially amenable to therapeutic intervention. These studies also suggest that properties of the host response with depletion of naïve T cells and accumulation of terminal-effector T cells may contribute to the biologic basis of disease risk. Properties of immune microenvironment identified here may also impact optimal application of immune therapies, including T cell-redirection approaches in childhood leukemia.
Authors
Jithendra Kini Bailur, Samuel S. McCachren, Katherine E. Pendleton, Juan C. Vasquez, Hong S. Lim, Alyssa Duffy, Deon Doxie, Akhilesh Kaushal, Connor J.R. Foster, Deborah DeRyckere, Sharon M. Castellino, Melissa L. Kemp, Peng Qiu, Madhav Dhodapkar, Kavita Dhodapkar
Abstract
COVID-19-associated morbidity and mortality have been attributed to a pathologic host response. Two divergent hypotheses have been proposed: a hyper-inflammatory ‘cytokine-storm’-mediated injury versus failure of host protective immunity resulting in unrestrained viral dissemination and organ injury. A key explanation for the inability to address this controversy has been the lack of diagnostic tools to evaluate immune function in COVID-19 infections. ELISpot, a highly sensitive, functional immunoassay was employed in 27 COVID-19, 51 septic, 18 critically-ill non-septic (CINS), and 27 healthy controls to evaluate adaptive and innate immune status by quantitating T cell IFN-ɣ and monocyte TFN-α production. Circulating T cell subsets were profoundly reduced in COVID-19 patients. Additionally, stimulated blood mononuclear cells produced less than 40% to 50% of the IFN-ɣ and TNF-α observed in septic and CINS patients, consistent with markedly impaired immune effector cell function. Approximately 25% of COVID-19 patients had increased IL-6 levels greater than 1,000 pg/mL that were not associated with elevations in other canonical pro-inflammatory cytokines. Collectively, these findings support the hypothesis that COVID-19 suppresses host functional adaptive and innate immunity. Importantly, Interleukin-7 administered ex vivo restored T cell IFN-ɣ production in COVID-19 patients. Thus, ELISpot may functionally characterize host immunity in COVID-19 and inform prospective therapies.
Authors
Kenneth E. Remy, Monty Mazer, David A. Striker, Ali H. Ellebedy, Andrew H. Walton, Jacqueline Unsinger, Teresa M. Blood, Philip A. Mudd, Daehan J. Yi, Daniel A. Mannion, Dale F. Osborne, R. Scott Martin, Nitin J. Anand, James P. Bosanquet, Jane Blood, Anne M. Drewry, Charles C. Caldwell, Isaiah R. Turnbull, Scott C. Brakenridge, Lyle L. Moldawer, Richard S. Hotchkiss
Abstract
The regulatory mechanisms enabling the intestinal epithelium to maintain a high degree of regenerative capacity during mucosal injury remain unclear. Ex vivo survival and clonogenicity of intestinal stem cells (ISCs) strictly required Cdc42-mediated growth response and Cdc42-deficient enteroids undergo rapid apoptosis. Mechanistically, Cdc42 engaging with EGFR was required for EGF-stimulated receptor-mediated endocytosis and sufficient to promote MAPK signaling. Proteomics and kinase analysis revealed that a physiological, but non-conventionally, spliced Cdc42 variant 2 (V2), exhibited stronger MAPK-activating capability. Human CDC42-V2 is transcriptionally elevated in some colon tumor tissues. Accordingly, mice engineered to overexpress Cdc42-V2 in intestinal epithelium showed elevated MAPK signaling, enhanced regeneration, and reduced mucosal damage in response to irradiation. Overproducing Cdc42-V2 specifically in mouse ISCs enhanced intestinal regeneration following injury. Thus, the intrinsic Cdc42-MAPK program is required for intestinal epithelial regeneration while elevating this signaling cascade is capable of initiating protection from genotoxic injury.
Authors
Xiao Zhang, Sheila Bandyopadhyay, Leandro P. Araujo, Kevin Tong, Juan Flores, Daniel Laubitz, Yanlin Zhao, George Yap, Jingren Wang, Qingze Zou, Ronaldo P. Ferraris, Lanjing Zhang, Wenwei Hu, Edward M. Bonder, Pawel R. Kiela, Robert J. Coffey, Michael Verzi, Ivaylo I. Ivanov, Nan Gao
Abstract
Histone deacetylase (HDAC) enzymes regulate transcription through epigenetic modification of chromatin structure, but their specific functions in the kidney remain elusive. We discovered that the human kidney expresses class I HDACs. Kidney medullary-specific inhibition of class I HDACs in the rat during high salt feeding results in hypertension, polyuria, hypokalemia, and nitric oxide (NO) deficiency. Three new, inducible murine models were used to determine that HDAC1 and HDAC2 in the kidney epithelium are necessary for maintaining epithelial integrity and maintaining fluid-electrolyte balance during increased dietary sodium intake. Moreover, single nucleus RNA sequencing determined that epithelial HDAC1 and HDAC2 are necessary for expression of many sodium or water transporters and channels. In performing a systematic review and meta-analysis of serious adverse events associated with clinical HDAC inhibitor use, we found that HDAC inhibitors increased the odds ratio of experiencing fluid-electrolyte disorders such as hypokalemia. This study provides insight on the mechanisms of potential serious adverse events with HDAC inhibitors, which may be fatal to critically ill patients. In conclusion, kidney tubular HDACs provide a link between the environment, such as consumption of high salt diets, with regulation of homeostatic mechanisms to remain in fluid-electrolyte balance.
Authors
Kelly A. Hyndman, Joshua S. Speed, Luciano D. Mendoza, John Allan, Jackson Colson, Randee Sedaka, Chunhua Jin, Hyun Jun Jung, Samir El-Dahr, David Pollock, Jennifer Pollock.
Abstract
Over the last years, a number of drugs have been approved for the treatment of cystic fibrosis (CF). Among them, the new Trikafta, a combination of three drugs, holds great promises to radically improve the quality of life for a large part of CF patients carrying one copy of the most frequent CFTR mutation: F508del. Currently available, disease-modifying, CF drugs work by rescuing the function of mutated CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) anion channel. Recent research work shows that membrane lipids, and the cell lipidome in general, play a significant role in the mechanism of CFTR defective trafficking and, on the other hand, in its rescue. In this paper, by using untargeted lipidomics on CFBE41o– cells, we identified distinctive changes in bronchial epithelial cell lipidome associated with treatment with the triple combination VX-661/VX-445/VX-770 (drug name: Trikafta) and other CF drugs. Particularly interesting is the reduction of ceramide levels, known molecular players in the induction of apoptosis, that appears to be associated with a decrease in cell susceptibility to undergo apoptosis. This evidence could account for additional beneficial role of the triple combination on CF phenotypes.
Authors
Nara Liessi, Emanuela Pesce, Clarissa Braccia, Sine Mandrup Bertozzi, Alessandro Giraudo, Tiziano Bandiera, Nicoletta Pedemonte, Andrea Armirotti
Abstract
We identified a novel homozygous duplication involving the promoter region and exons 1-4 of RYR2 that is responsible for highly penetrant, exertion-related sudden deaths/cardiac arrests in the Amish community without an overt phenotype to suggest RYR2-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT). Homozygous RYR2-duplication (RYR2-DUP) induced pluripotent stem cell-cardiomyocytes (iPSC-CMs) were generated from two unrelated patients. There was no difference in baseline Ca2+ handling measurements between WT- and the RYR2-DUP-iPSC-CMs lines. However, compared to WT-iPSC-CMs, both patient lines demonstrated a dramatic reduction in caffeine and isoproterenol (ISO) stimulated Ca2+ transient amplitude, suggesting RyR2 loss-of-function. There was a >50% reduction in RYR2 transcript/RyR2 protein expression in both patient iPSC-CMs compared to WT. Delayed afterdepolarization was observed in the RYR2-DUP-iPSC-CMs but not in the WT-iPSC-CMs. Compared to WT-iPSC-CMs, there was a significantly elevated arrhythmic activity in the RYR2-DUP-iPSC-CMs in response to ISO. Nadolol, propranolol, and flecainide reduced erratic activity by 8.5 fold, 6.8 fold, and 2.4 fold, respectively from ISO challenge. Unlike the gain-of-function mechanism observed in RYR2-mediated CPVT, the homozygous multi-exon duplication precipitates a dramatic reduction in RYR2 transcription and RyR2 protein translation, a loss-of-function in calcium handling, and a calcium-induced calcium release apparatus that is insensitive to catecholamines and caffeine.
Authors
David J. Tester, CS John Kim, Samantha K. Hamrick, Dan Ye, Bailey J. O'Hare, Hannah M. Bombei, Kristi K. Fitzgerald, Carla M. Haglund-Turnquist, Dianne L. Atkins, Luis A. Ochoa Nunez, Ian H. Law, Joel D. Temple, Michael J. Ackerman
Abstract
BACKGROUND. Metabolically healthy obesity (MHO) and metabolically healthy overweight (MH-OW) have been suggested to be an important and emerging phenotype with an increased risk of cardiovascular disease (CVD). However, whether MHO and MH-OW are associated with all-cause mortality remains inconsistent. METHODS. The association of MHO and MH-OW and all-cause mortality was determined in China community-based prospective cohort study (Kailuan Study) including 93,272 adults at baseline. Data were analyzed from 2006 to 2017. Participants were categorized into six mutually exclusive groups according to the body mass index (BMI) and metabolic syndrome (MetS) status. The primary outcome is all-cause death, whereas accidental deaths were excluded. RESULTS. During a median follow-up of 11.04 years (interquartile range: 10.74-11.22 years), 8,977 deaths occurred. Compared to healthy participants with normal BMI (MH-NW), MH-OW had lowest risk of all-cause mortality (multivariate-adjusted hazard ratio [aHR]: 0.926; 95% confidence interval [CI]: 0.861 to 0.997), whereas there was no increased or decreased risk for MHO (aHR: 1.009; 95% CI: 0.886 to 1.148). Stratified analyses and sensitivity analyses further validated that nonsignificant association between MHO and all-cause mortality. CONCLUSIONS. Overweight and obesity do not predicate increased risk of all-cause mortality in metabolic healthy Chinese individuals.
Authors
Qiuyue Tian, Anxin Wang, Yingting Zuo, Shuohua Chen, Haifeng Hou, Wei Wang, Shouling Wu, Youxin Wang
Abstract
Mutations in PKD1 (encoding for Polycystin-1, PC1) are found in 80-85% of patients with ADPKD. We tested the hypothesis that changes in actin dynamics result from PKD1 mutations through dysregulation of compartmentalised centrosomal RhoA signalling mediated by specific RhoGAP (ARHGAP) proteins resulting in the complex cellular cystic phenotype. Initial studies revealed that the actin cytoskeleton was highly disorganised in PKD1 patient-derived cells and was associated with an increase in total and centrosomal RhoA activation and ROCK signalling. Using cilia length as a phenotypic readout for centrosomal RhoA activity, we identified ARHGAP5, 29, 35 as essential regulators of ciliation in normal human renal tubular cells. Importantly, a specific decrease in centrosomal ARHGAP35 was observed in PKD1 null cells using a centrosome-targeted proximity ligation assay and by immunofluorescence labelling. Finally, we demonstrate that another ROCK inhibitor (hydroxyfasudil) reduced cyst expansion in both human PKD1 3D cyst assays and an inducible Pkd1 mouse model. In summary, we report a novel interaction between PC1 and ARHGAP35 in the regulation of centrosomal RhoA activation and ROCK signalling. Targeting the RhoA/ROCK pathway inhibited cyst formation in vitro and in vivo indicating its relevance to ADPKD pathogenesis and for developing new therapies to inhibit cyst initiation.
Authors
Andrew J. Streets, Philipp P. Prosseda, Albert C.M. Ong
Abstract
Clostridioides difficile is a leading cause of nosocomial infection responsible for significant morbidity and mortality with limited options for therapy. Secreted C. difficile toxin B (TcdB) is a major contributor to disease pathology and select TcdB-specific Abs may protect against disease recurrence. However, the high frequency of recurrence suggests that the memory B cell response, essential for new Ab production following C. difficile re-exposure, is insufficient. We therefore isolated TcdB-specific memory B cells from individuals with a history of C. difficile infection and performed single-cell deep sequencing of their Ab genes. Herein, we report that TcdB-specific memory B cell-encoded antibodies showed somatic hypermutation but displayed limited isotype class switch. Memory B cell-encoded monoclonal antibodies generated from the gene sequences revealed low to moderate affinity for TcdB and a limited ability to neutralize TcdB. These findings indicate that memory B cells are an important factor in C. difficile disease recurrence.
Authors
Hemangi B. Shah, Kenneth Smith, Edgar J. Scott, II, Jason L. Larabee, Judith A. James, Jimmy D. Ballard, Mark L. Lang
Abstract
Post-prandial triglycerides (TGs) are elevated in people with type 2 diabetes (T2D) and glucoregulatory agents such as Glucagon-like-peptide-1 (GLP-1) receptor agonists and Dipeptidyl Peptidase-4 (DPP-4) inhibitors simultaneously reduce post-prandial TG excursion. Although the glucose-lowering mechanisms of DPP-4 have been extensively studied, how the reduction of DPP-4 activity improves lipid tolerance remains unclear. Here we demonstrate that gut-selective and systemic inhibition of DPP-4 activity reduces post-prandial TG excursion in young mice. Genetic inactivation of Dpp4 simultaneously within endothelial cells (ECs) and hematopoietic cells using Tie2-Cre reduces intestinal lipoprotein secretion under regular chow (RC) diet conditions. Bone marrow transplantation revealed a key role for hematopoietic cells in modulation of lipid responses arising from genetic reduction of DPP-4 activity. Unexpectedly, deletion of Dpp4 in enterocytes increases TG excursion in high fat diet (HFD)-fed mice. Moreover, chemical reduction of DPP-4 activity and increased levels of GLP-1 are uncoupled from triglyceride excursion in older or HFD-fed mice, yet lipid tolerance remains improved in older Dpp4-/- and Dpp4EC-/- mice. Taken together, this study defines new roles for specific DPP-4 compartments, age, and diet as modifiers of DPP-4 activity linked to control of gut lipid metabolism.
Authors
Elodie M. Varin, Antonio Hanson, Jacqueline L. Beaudry, My-Anh Nguyen, Xiemin Cao, Laurie Baggio, Erin E. Mulvihill, Daniel J. Drucker
Abstract
Recent evidence shows that the naïve heart harbors a population of intravascular recirculating B cells that make close contact with the microvascular endothelium of the heart and arrest their transit as they pass through the heart. However, the timing of their appearance and their organ specificity remain unknown. To address this knowledge gap, we performed a systematic analysis of B cells isolated from the myocardium and other organs, from embryonic life to early adulthood. We found that B cells are present in the developing heart by day E13.5. The phenotype of myocardial B cells changed dynamically during development. While neonatal heart B cells were mostly CD11b+ and CD11b-CD21-CD23-, adult B cells were predominantly CD11b-CD21+CD23+. Histological analysis and intravital microscopy of lung and liver showed that organ-associated B cells in contact with the microvascular endothelium were not specific to the heart. Flow cytometric analysis of perfused hearts, livers, lungs and spleen at different developmental stages showed that the dynamic changes in B cell subpopulations observed in the heart during development mirrored changes observed in the spleen, peripheral blood and other organs. Single cell RNAseq analysis of B cells showed that myocardial-associated B cells were part of a larger population of organ-associated B cells that had a distinct gene expression profile. These findings broaden our understanding of the biology of myocardial-associated B cells and suggest that current models of the dynamics of naïve B cell during development are incomplete.
Authors
Cibele Rocha-Resende, Wei Yang, Wenjun Li, Daniel Kreisel, Luigi Adamo, Douglas Mann
Abstract
Skin lesions in dermatomyositis (DM) patients are common, frequently refractory, and have prognostic significance. Histologically, DM lesions appear like cutaneous lupus erythematosus (CLE) lesions and frequently cannot be differentiated. We thus undertook to examine the transcriptional profile of DM biopsies and compared them to CLE lesions in order to identify unique features. Type I interferon (IFN) signaling, including upregulation of IFN kappa, was a common pathway in both DM and CLE, but CLE also exhibited other inflammatory pathways. Importantly, DM lesions could be distinguished from CLE by a 5-gene biomarker panel that included an upregulation of IL18. Using single-cell RNA-sequencing, we further identified keratinocytes as the main source of increased IL-18 in DM skin. The novel molecular signature identified in this study has significant clinical implications for differentiating DM from CLE lesions, and we have highlighted the potential role for IL-18 in the pathophysiology of DM skin disease.
Authors
Lam Tsoi, Mehrnaz Gharaee-Kermani, Celine C. Berthier, Tori Nault, Grace Hile, Shannon N. Estadt, Matthew T. Patrick, Rachael Wasikowski, Allison C. Billi, Lori Lowe, Tamra J. Reed, Johann Gudjonsson, J. Michelle Kahlenberg
Abstract
Background: Our objective is to investigate whether primary Sjogren’s syndrome (pSS) is associated with multiple system atrophy (MSA). Methods: We performed a retrospective cohort study assessing rates of (a) MSA in a cohort of patients with pSS, and (b) and rates of pSS in a cohort of patients with MSA. These data were, compared to rates in respective control groups. We additionally reviewed the neuropathologic findings in two patients with pSS, cerebellar degeneration, parkinsonism, and autonomic dysfunction. Results: Our cohort of 308 pSS patients had a greater incidence of MSA compared with four large population-based studies and had had a significantly higher prevalence of at least probable MSA (1% vs. 0%, p = 0.02) compared to 776 patients in a control cohort of patients with other autoimmune disorders. Our cohort of 26 autopsy-proven MSA patients had a significantly higher prevalence of pSS compared with a cohort of 115 patients with other autopsy-proven neurodegenerative disorders (8% vs. 0%, p = 0.03). The two patients we described with pSS and progressive neurodegenerative disease showed classic MSA pathology at autopsy. Conclusion: Our findings provide evidence for an association between MSA and pSS that is specific to both pSS, among autoimmune disorders, and MSA, among neurodegenerative disorders. The two cases we describe of autopsy-proven MSA support that MSA pathology can explains neurologic disease in a subset of pSS patients. These findings together support the hypothesis that systemic autoimmune disease plays role in neurodegeneration. Study funding: The Michigan Brain Bank is supported in part through an NIH grant P30AG053760.
Authors
Kyle S. Conway, Sandra Camelo-Piragua, Amanda O. Fisher-Hubbard, William Perry, Vikram G. Shakkottai, Sriram Venneti
