Cancer cachexia is a major cause of patient morbidity and mortality, with no efficacious treatment or management strategy. Despite sharing pathophysiological features with a number of neuromuscular wasting conditions, including age-related sarcopenia, the mechanisms underlying cachexia remain poorly understood. Studies of related conditions suggest that pathological targeting of the neuromuscular junction (NMJ) may play a key role in cachexia, but this has yet to be investigated in human patients. Here, high-resolution morphological analyses were undertaken on NMJs of rectus abdominis obtained from patients undergoing upper GI cancer surgery compared with controls (N=30; n=1,165 NMJs). Cancer patients included those with cachexia and weight-stable disease. Despite the low skeletal muscle index and significant muscle fibre atrophy in patients with cachexia, NMJ morphology was fully conserved. No significant differences were observed in any of the pre- and post-synaptic variables measured. We conclude that NMJs remain structurally intact in rectus abdominis in both cancer and cachexia, suggesting that denervation of skeletal muscle is not a major driver of pathogenesis. The absence of NMJ pathology is in stark contrast to related conditions, such as age-related sarcopenia, and supports the hypothesis that intrinsic changes within skeletal muscle, independent of any changes in motor neurons, represent the primary locus of neuromuscular pathology in cancer cachexia.
Ines Boehm, Janice Miller, Thomas M. Wishart, Stephen J. Wigmore, Richard J.E. Skipworth, Ross A. Jones, Thomas H. Gillingwater
Chikungunya virus (CHIKV) is an arbovirus capable of causing a severe and often debilitating rheumatic syndrome in humans. CHIKV replicates in a wide variety of cell types in mammals, which has made attributing pathologic outcomes to replication at specific sites difficult. To assess the contribution of CHIKV replication in skeletal muscle cells to pathogenesis, we engineered a CHIKV strain exhibiting restricted replication in these cells via incorporation of target sequences for skeletal muscle cell-specific miR-206. This virus, which we term SKE, displayed diminished replication in skeletal muscle cells in a mouse model of CHIKV disease. Mice infected with SKE developed less severe disease signs, including diminished swelling in the inoculated foot and less necrosis and inflammation in the interosseous muscles. SKE infection was associated with diminished infiltration of T cells into the interosseous muscle as well as decreased production of IL-1b, IL-6, IP-10, and TNFa. Importantly, blockade of the IL-6 receptor led to diminished swelling of a control CHIKV strain capable of replication in skeletal muscle, reducing swelling to levels observed in mice infected with SKE. These data implicate replication in skeletal muscle cells and release of IL-6 as important mediators of CHIKV disease.
Anthony J. Lentscher, Mary K. McCarthy, Nicholas A. May, Bennett J. Davenport, Stephanie A. Montgomery, Krishnan Raghunathan, Nicole McAllister, Laurie A. Silva, Thomas E. Morrison, Terence S. Dermody
Ventriculomegaly and hydrocephalus are associated with loss of function of glycine decarboxylase (Gldc) in mice and in humans suffering from Non-Ketotic Hyperglycinemia (NKH), a neurometabolic disorder characterised by accumulation of excess glycine. Here, we showed that ventriculomegaly in Gldc-deficient mice is preceded by stenosis of the Sylvian aqueduct and malformation or absence of the sub-commissural organ and pineal gland. Gldc functions in the glycine cleavage system, a mitochondrial component of folate metabolism, whose malfunction results in accumulation of glycine and diminished supply of glycine-derived one-carbon units to the folate cycle. We showed that inadequate one-carbon supply, as opposed to excess glycine is the cause of hydrocephalus associated with loss of function of the glycine cleavage system. Maternal supplementation with formate prevented both ventriculomegaly, as assessed at pre-natal stages, and post-natal development of hydrocephalus in Gldc-deficient mice. Furthermore, ventriculomegaly was rescued by genetic ablation of 5,10-methylene tetrahydrofolate reductase (Mthfr), which results in retention of one-carbon groups in the folate cycle at the expense of transfer to the methylation cycle. In conclusion, a defect in folate metabolism can lead to pre-natal aqueduct stenosis and resultant hydrocephalus. These defects are preventable by maternal supplementation with formate, which acts as a one-carbon donor.
Chloe Santos, Yun Jin Pai, M. Raasib Mahmood, Kit-Yi Leung, Dawn Savery, Simon N. Waddington, Andrew J. Copp, Nicholas D.E. Greene
Epigenetic integrity is critical for many eukaryotic cellular processes. An important question is how different epigenetic regulators control development and impact disease. Lysine acetyltransferase 8 (KAT8) is critical for acetylation of histone H4 at lysine 16 (H4K16), an evolutionarily conserved epigenetic mark. It is unclear what roles KAT8 plays in cerebral development and human disease. Here, we report that cerebrum-specific knockout mice displayed cerebral hypoplasia in the neocortex and hippocampus, along with improper neural stem and progenitor cell (NSPC) development. Mutant cerebrocortical neuroepithelia exhibited faulty proliferation, aberrant neurogenesis, massive apoptosis and scant H4K16 propionylation. Mutant NSPCs formed poor neurospheres, and pharmacological KAT8 inhibition abolished neurosphere formation. Moreover, we describe KAT8 variants in nine patients with intellectual disability, seizures, autism, dysmorphisms and other anomalies. The variants altered chromobarrel and catalytic domains of KAT8, thereby impairing nucleosomal H4K16 acetylation. Valproate was effective for treating epilepsy in at least two of the individuals. This study uncovers a critical role of KAT8 in cerebral and NSPC development, identifies nine individuals with KAT8 variants, and links deficient H4K16 acylation directly to intellectual disability, epilepsy and other developmental anomalies.
Lin Li, Mohammad Ghorbani, Monika Weisz-Hubshman, Justine Rousseau, Isabelle Thiffault, Rhonda E. Schnur, Catherine Breen, Renske Oegema, Marjan M.M. Weiss, Quinten Waisfisz, Sara Welner, Helen Kingston, Jordan A. Hills, Elles M.J. Boon, Lina Basel-Salmon, Osnat Konen, Hadassa Goldberg-Stern, Lily Bazak, Shay Tzur, Jianliang Jin, Xiuli Bi, Michael Bruccoleri, Kirsty McWalter, Megan T. Cho, Maria Scarano, G. Bradley Schaefer, Susan S. Brooks, Susan Starling Hughes, K.L.I. van Gassen, Johanna M. van Hagen, Tej K. Pandita, Pankaj B. Agrawal, Philippe M. Campeau, Xiang-Jiao Yang
Omalizumab is an anti-IgE monoclonal antibody (mAb) approved for the treatment of severe asthma and chronic spontaneous urticaria. Use of Omalizumab is associated with reported side effects, ranging from local skin inflammation at the injection site to systemic anaphylaxis. To date, the mechanisms through which Omalizumab induces adverse reactions are still unknown. Here, we demonstrated that immune complexes formed between Omalizumab and IgE can induce both skin inflammation and anaphylaxis through engagement of IgG receptors (FcγRs) in FcγR-humanized mice. We further developed an Fc-engineered mutant version of Omalizumab, and demonstrated that this mAb is equally potent as Omalizumab at blocking IgE-mediated allergic reactions, but does not induce FcγR-dependent adverse reactions. Overall, our data indicate that Omalizumab can induce skin inflammation and anaphylaxis by engaging FcγRs, and demonstrate that Fc-engineered versions of the mAb could be used to reduce such adverse reactions.
Bianca Balbino, Pauline Herviou, Ophélie Godon, Julien Stackowicz, Odile Richard-Le Goff, Bruno Iannascoli, Delphine Sterlin, Sébastien Brûlé, Gael A. Millot, Faith M. Harris, Vera A. Voronina, Kari C. Nadeau, Lynn E. Macdonald, Andrew J. Murphy, Pierre Bruhns, Laurent L. Reber
High levels of ecto-5'-nucleotidase (CD73) have been implicated in immune suppression and tumor progression, and have also been observed in cancer patients who progress on anti-PD-1 immunotherapy. While regulatory T cells can express CD73 and inhibit T cell responses via the production of adenosine, less is known about CD73 expression in other immune cell populations. We found that tumor-infiltrating NK cells upregulate CD73 expression and the frequency of these CD73+ NK cells correlated with larger tumor size in breast cancer patients. In addition, the expression of multiple alternative immune checkpoint receptors including LAG-3, VISTA, PD-1, and PD-L1 was significantly higher in CD73 positive NK cells than in CD73 negative NK cells. Mechanistically, NK cells transport CD73 in intracellular vesicles to the cell surface and the extracellular space via actin polymerization-dependent exocytosis upon engagement of 4-1BBL on tumor cells. These CD73 positive NK cells undergo transcriptional reprogramming and upregulate IL10 production via STAT3 transcriptional activity, suppressing CD4 T cell proliferation and IFN-ɣ production. Taken together, our results support that tumors can hijack NK cells as a means to escape immunity and that CD73 expression defines an inducible population of NK cells with immune regulatory properties within the tumor microenvironment.
Shi Yong Neo, Ying Yang, Record Julien, Ran Ma, Xinsong Chen, Ziqing Chen, Nicholas P. Tobin, Emily Blake, Christina Seitz, Ron Thomas, Arnika Kathleen Wagner, John Andersson, Jana de Boniface, Jonas Bergh, Shannon Murray, Evren Alici, Richard Childs, Martin Johansson, Lisa S. Westerberg, Felix Haglund, Johan Hartman, Andreas Lundqvist
The drug efflux pump ABCB1 is a key driver of chemoresistance, and high expression predicts for treatment failure in acute myeloid leukemia (AML). In this study, we identified and functionally validated the network of enhancers that controls expression of ABCB1. We show that exposure of leukemia cells to daunorubicin activated an integrated stress response-like transcriptional program to induce ABCB1 through remodeling and activation of an ATF4-bound, stress-responsive enhancer. Protracted stress primed enhancers for rapid increases in activity following re-exposure of cells to daunorubicin, providing an epigenetic memory of prior drug treatment. In primary human AML, exposure of fresh blast cells to daunorubicin activated the stress-responsive enhancer and led to dose-dependent induction of ABCB1. Dynamic induction of ABCB1 by diverse stressors, including chemotherapy, facilitated escape of leukemia cells from targeted third-generation ABCB1 inhibition, providing an explanation for the failure of ABCB1 inhibitors in clinical trials. Stress-induced up regulation of ABCB1 was mitigated by combined use of pharmacologic inhibitors U0126 and ISRIB, which inhibit stress signalling and have potential for use as adjuvants to enhance the activity of ABCB1 inhibitors.
Mark S. Williams, Fabio M.R. Amaral, Fabrizio Simeoni, Tim C.P. Somervaille
Immune response to therapeutic enzymes poses a detriment to patient safety and treatment outcome. Enzyme replacement therapy (ERT) is a standard therapeutic option for some types of Mucopolysaccharidoses including Morquio A syndrome caused by GALNS deficiency. Current protocols tolerize patients using cytotoxic immunosuppressives which can cause adverse effects. Here we show development of tolerance in Morquio A mice via oral delivery of peptide or GALNS during ten days prior to ERT. Our results show that using an immunodominant peptide (I10) or the complete enzyme (GALNS) to orally induce tolerance to GALNS prior to ERT, resulted in several improvements to ERT in mice: i) decreased splenocyte proliferation after in-vitro GALNS stimulation; ii) modulation of cytokine secretion profile; iii) decline in GALNS-specific IgG or IgE plasma; iv) decreased GAG storage in liver; and v) fewer circulating immune-complexes in plasma. This model could be extrapolated to other lysosomal storage disorders where immune response hinders ERT.
Angela C. Sosa, Barbara Kariuki, Qi Gan, Alan P. Knutsen, Clifford J. Bellone, Miguel A. Guzmán, Luis A. Barrera, Shunji Tomatsu, Anil K. Chauhan, Eric Armbrecht, Adriana M. Montaño
A single sub-anesthetic dose of ketamine, an NMDA receptor (NMDAR) antagonist, produces rapid and sustained antidepressant actions in depressed patients, addressing a major unmet need for the treatment of mood disorders. Ketamine produces a rapid increase in extracellular glutamate and synaptic formation in the prefrontal cortex, but the initial cellular trigger that initiates these and its behavioral actions has not been identified. To address this question, we used a combination of viral shRNA and conditional mutation to produce cell specific knockdown or deletion of a key NMDAR subunit, GluN2B, implicated in the actions of ketamine. The results demonstrate that the antidepressant actions of ketamine were blocked by GluN2B-NMDAR knockdown on GABA (Gad1) interneurons, as well as subtypes expressing somatostatin (Sst), or parvalbumin (Pvalb), but not glutamate principle neurons in the mPFC. Further analysis of GABA subtypes showed that cell specific knockdown or deletion of GluN2B in Sst interneurons blocked or occluded the antidepressant actions of ketamine and revealed sex-specific differences that are associated with excitatory postsynaptic currents on mPFC principle neurons. These findings demonstrate that GluN2B-NMDARs on GABA interneurons are the initial cellular trigger for the rapid antidepressant actions of ketamine and show sex-specific adaptive mechanisms to GluN2B modulation.
Danielle M. Gerhard, Santosh Pothula, Rong-Jian Liu, Min Wu, Xiao-Yuan Li, Matthew J. Girgenti, Seth R. Taylor, Catharine H. Duman, Eric Delpire, Marina Picciotto, Eric S. Wohleb, Ronald S. Duman
Background: Ceramides are sphingolipids that play causative roles in diabetes and heart disease, with their serum levels measured clinically as biomarkers of cardiovascular disease (CVD). Methods: We performed targeted lipidomics on serum samples of individuals with familial coronary artery disease (CAD) (n = 462) and population-based controls (n = 212) to explore the relationship between serum sphingolipids and CAD, employing unbiased machine learning to identify sphingolipid species positively associated with CAD. Results: Nearly every sphingolipid measured (n = 30 of 32) was significantly elevated in subjects with CAD compared with population controls. We generated a novel Sphingolipid Inclusive CAD risk score, termed SIC, that demarcates CAD patients independently and more effectively than conventional clinical CVD biomarkers including LDL-cholesterol and serum triglycerides. This new metric comprises several minor lipids which likely serve as measures of flux through the ceramide biosynthesis pathway, rather than the abundant deleterious ceramide species that are incorporated in other ceramide-based scores. Conclusion: This study validates serum ceramides as candidate biomarkers of cardiovascular disease and suggests that comprehensive sphingolipid panels be considered as measures of CVD.
Annelise M. Poss, J. Alan Maschek, James E. Cox, Benedikt J. Hauner, Paul N. Hopkins, Steven C. Hunt, William L. Holland, Scott A. Summers, Mary C. Playdon
Pattern recognition receptors (PRRs) are crucial for responses to infections and tissue damage, however, their role in autoimmunity is less clear. Herein we demonstrate that two C-type lectin receptors (CLRs), Mcl and Mincle, play an important role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of Multiple Sclerosis (MS). Congenic rats expressing lower levels of Mcl and Mincle on myeloid cells exhibited a drastic reduction in EAE incidence. In vivo silencing of Mcl and Mincle or blockade of their endogenous ligand SAP130 revealed that receptors expression in the central nervous system is crucial for the T cell recruitment and reactivation into a pathogenic Th17/GM-CSF phenotype. Consistent with this, we uncovered MCL/MINCLE-expressing cells in brain lesions of MS patients and we further found an upregulation of the MCL/MINCLE signaling pathway and an increased response following MCL/MINCLE stimulation in peripheral blood mononuclear cells from MS patients. Together these data support a role for CLRs in autoimmunity and implicate the MCL/MINCLE pathway as a potential therapeutic target in MS.
Marie N'diaye, Susanna Brauner, Sevasti Flytzani, Lara Kular, Andreas Warnecke, Milena Z. Adzemovic, Eliane Piket, Jin-Hong Min, Will Edwards, Filia Mela, Hoi Ying Choi, Vera Magg, Tojo James, Magdalena Linden, Holger M. Reichardt, Michael R. Daws, Jack van Horssen, Ingrid Kockum, Robert A. Harris, Tomas Olsson, Andre O. Guerreiro-Cacais, Maja Jagodic
Neuronal hyperexcitability and cytoplasmic mislocalization of the nuclear RNA binding proteinTDP43 are universal features in amyotrophic lateral sclerosis (ALS), but the relationship between these phenomena remains poorly defined. Here, we show that neuronal hyperexcitability drives TDP43 pathology by upregulating shortened (s)TDP43 splice variants missing the canonical C-terminus. sTDP43 isoforms preferentially accumulate in the cytoplasm,forming insoluble inclusions that sequester full-length TDP43 via preserved N-terminal interactions. Consistent with these findings, sTDP43 overexpression is highly toxic to mammalian neurons, suggesting that neurodegeneration results from complementary gain- and loss-of-function mechanisms. In humans and mice, sTDP43 transcripts are significantly enriched in vulnerable motor neurons, and we observed a striking accumulation of sTDP43 protein within neurons and glia of ALS patients. These studies uncover a hitherto unknown role of alternative TDP43 splice isoforms in ALS, and indicate that sTDP43 production may be a key contributor to the susceptibility of motor neurons in ALS.
Kaitlin Weskamp, Elizabeth M. Tank, Roberto Miguez, Jonathon P. McBride, Nicolás B. Gómez, Matthew White, Ziqiang Lin, Carmen Moreno Gonzalez, Andrea Serio, Jemeen Sreedharan, Sami J. Barmada
Influenza A virus (IAV) is among the most common causes of pneumonia related death worldwide. Pulmonary epithelial cells are the primary target for viral infection and replication and respond by releasing inflammatory mediators that recruit immune cells to mount the host response. Severe lung injury and death during IAV infection results from an exuberant host inflammatory response. The linear ubiquitin assembly complex (LUBAC), composed of SHARPIN, HOIL-1L and HOIP, is a critical regulator of NF-κB-dependent inflammation. Using mice with lung epithelial specific deletions of HOIL-1L or HOIP in a model of IAV infection, we provided evidence that, while a reduction in the inflammatory response was beneficial, ablation of the LUBAC-dependent lung epithelial-driven response worsened lung injury and increased mortality. Moreover, we described a mechanism for the upregulation of HOIL-1L in infected and non-infected cells triggered by the activation of type I interferon receptor and mediated by IRF1, which was maladaptive and contributed to hyper-inflammation. Thus, we propose that lung epithelial LUBAC acts as a molecular rheostat that could be selectively targeted to modulate the immune response in patients with severe IAV-induced pneumonia.
Patricia L. Brazee, Luisa Morales-Nebreda, Natalia D. Magnani, Joe G.N. Garcia, Alexander V. Misharin, Karen M. Ridge, G.R. Scott Budinger, Kazuhiro Iwai, Laura A. Dada, Jacob I. Sznajder
Cancer immune evasion is achieved through multiple layers of immune tolerance mechanisms including immune editing, recruitment of tolerogenic immune cells, and secretion of immune suppressive cytokines. Recent success with immune checkpoint inhibitors in cancer immunotherapy suggests a dysfunctional immune synapse as a pivotal tolerogenic mechanism. Tumor cells express immune synapse proteins to suppress the immune system, which is often modulated by epigenetic mechanisms. When the methylation status of key immune synapse genes was interrogated, we observed disproportionately hyper-methylated co-stimulatory genes and hypo-methylation of immune checkpoint genes, which were negatively associated with functional T-cell recruitment to the tumor microenvironment. Therefore, the methylation status of immune synapse genes reflects tumor immunogenicity and correlates with survival.
Anders Berglund, Matthew Mills, Ryan M. Putney, Imène Hamaidi, James Mulé, Sungjune Kim
Increases in the number of cell therapies in the preclinical and clinical phases have prompted the need for reliable and non-invasive assays to validate transplant function in clinical biomanufacturing. We developed a robust characterization methodology composed of quantitative bright-field absorbance microscopy (QBAM) and deep neural networks (DNNs) to non-invasively predict tissue function and cellular donor identity. The methodology was validated using clinical-grade induced pluripotent stem cell derived retinal pigment epithelial cells (iPSC-RPE). QBAM images of iPSC-RPE were used to train DNNs that predicted iPSC-RPE monolayer transepithelial resistance, predicted polarized vascular endothelial growth factor (VEGF) secretion, and matched iPSC-RPE monolayers to the stem cell donors. DNN predictions were supplemented with traditional machine learning algorithms that identified shape and texture features of single cells that were used to predict tissue function and iPSC donor identity. These results demonstrate non-invasive cell therapy characterization can be achieved with QBAM and machine learning.
Nicholas J. Schaub, Nathan A. Hotaling, Petre Manescu, Sarala Padi, Qin Wan, Ruchi Sharma, Aman George, Joe Chalfoun, Mylene Simon, Mohamed Ouladi, Carl G. Simon, Jr., Peter Bajcsy, Kapil Bharti
Parkinson's disease (PD) is a neurodegenerative disorder associated with loss of striatal dopamine, secondary to degeneration of midbrain dopamine (mDA) neurons in the substantia nigra, rendering cell transplantation a promising therapeutic strategy. To establish human induced pluripotent stem cell (hiPSC)-based autologous cell therapy, we report a platform of core techniques for the production of mDA progenitors as a safe and effective therapeutic product. First, by combining metabolism-regulating microRNAs with reprogramming factors, we developed a method to more efficiently generate clinical grade iPSCs, as evidenced by genomic integrity and unbiased pluripotent potential. Second, we established a “spotting”-based in vitro differentiation methodology to generate functional and healthy mDA cells in a scalable manner. Third, we developed a chemical method that safely eliminates undifferentiated cells from the final product. Dopaminergic cells thus produced express high levels of characteristic mDA markers, produce and secrete dopamine, and exhibit electrophysiological features typical of mDA cells. Transplantation of these cells into rodent models of PD robustly restores motor dysfunction and reinnervates host brain, while showing no evidence of tumor formation or redistribution of the implanted cells. We propose that this platform is suitable for the successful implementation of human personalized autologous cell therapy for PD.
Bin Song, Young Cha, Sanghyeok Ko, Jeha Jeon, Nayeon Lee, Hyemyung Seo, Kyung-joon Park, In-Hee Lee, Claudia Lopes, Melissa Feitosa, María José Luna, Jin Hyuk Jung, Jisun Kim, Dabin Hwang, Bruce Cohen, Martin Teicher, Pierre Leblanc, Bob Carter, Jeffrey H. Kordower, Vadim Y. Bolshakov, Sek Won Kong, Jeffrey S. Schweitzer, Kwang-Soo Kim
Interventions to prevent HIV-1 infection and alternative tools in HIV cure therapy remain pressing goals. Recently, numerous broadly neutralizing HIV-1 monoclonal antibodies (bNAbs) have been developed which possess the characteristics necessary for potential prophylactic or therapeutic approaches. However, formulation complexities especially for multi-antibody deliveries, long infusion times, and production issues could limit the use of these bNAbs when deployed globally impacting their potential application. Here, we describe an approach utilizing synthetic DNA-encoded monoclonal antibodies (dMAbs) for direct in vivo production of prespecified neutralizing activity. We designed 16 different bNAbs as dMAbs cassettes and studied their activity in small and large animals. Sera from animals administered dMAbs neutralized multiple HIV-1 isolates with similar activity to their parental recombinant MAbs. Delivery of multiple dMAbs to a single animal led to increased neutralization breadth. Two dMAbs, PGDM1400 and PGT121, were advanced into non-human primates for study. High peak circulating levels (between 6-34µg/ml) of these dMAbs were measured and the sera of all animals displayed broad neutralizing activity. The dMAb approach provides an important local delivery platform for the in vivo generation of HIV-1 bNAbs and for other infectious disease antibodies.
Megan C. Wise, Ziyang Xu, Edgar Tello-Ruiz, Charles Beck, Aspen Trautz, Ami Patel, Sarah T.C. Elliott, Neethu Chokkalingam, Sophie Kim, Melissa G. Kerkau, Kar Muthumani, Jingjing Jiang, Paul Fisher, Stephany J. Ramos, Trevor R.F. Smith, Janess Mendoza, Kate E. Broderick, David C. Montefiori, Guido Ferrari, Daniel W. Kulp, Laurent Humeau, David B. Weiner
Background: Chronic HCV-infection is characterized by a severe impairment of HCV-specific CD4 T cell help that is driven by chronic antigen stimulation. We aimed to study the fate of HCV-specific CD4 T cells after viral elimination. Methods:HCV-specific CD4 T cell responses were longitudinally analyzed using MHC class II tetramer-technology, multicolor flow cytometry and RNA sequencing in a cohort of chronically HCV-infected patients undergoing therapy with direct-acting antivirals. In addition, HCV-specific neutralizing antibodies and CXCL13 levels were analyzed. Results: We observed that the frequency of HCV-specific CD4 T cells increased within two weeks after initiation of DAA therapy. Multicolor flow cytometry revealed a downregulation of exhaustion and activation markers and an upregulation of memory-associated markers. While cells with a Th1 phenotype were the predominant subset at baseline, cells with phenotypic and transcriptional characteristics of follicular T helper cells increasingly shaped the circulating HCV-specific CD4 T cell repertoire, suggesting antigen-independent survival of this subset. These changes were accompanied by a decline of HCV-specific neutralizing antibodies and the germinal center activity. Conclusion: We identified a population of HCV-specific CD4 T cells with a follicular T helper cell signature that is maintained after therapy-induced elimination of persistent infection and may constitute an important target population for vaccination efforts to prevent re-infection and immunotherapeutic approaches for persistent viral infections.
Maike Smits, Katharina Zoldan, Naveed Ishaque, Zuguang Gu, Katharina Jechow, Dominik Wieland, Christian Conrad, Roland Eils, Catherine Fauvelle, Thomas F. Baumert, Florian Emmerich, Bertram Bengsch, Christoph Neumann-Haefelin, Maike Hofmann, Robert Thimme, Tobias Boettler
Successful infection by mucosal pathogens requires overcoming the mucus barrier. To better understand this key step, we performed a survey of the interactions between human respiratory mucus and the human pathogen S. pneumoniae. Pneumococcal adherence to adult human nasal fluid was seen only by isolates expressing pilus-1. Robust binding was independent of pilus-1 adhesive properties but required Fab-dependent recognition of RrgB, the pilus shaft protein, by naturally-acquired secretory immunoglobulin A (sIgA). Pilus-1 binding by specific sIgA led to bacterial agglutination, but adherence required interaction of agglutinated pneumococci and entrapment in mucus particles. To test the effect of these interactions in vivo, pneumococci were preincubated with human sIgA prior to intranasal challenge in a mouse model of colonization. sIgA-treatment resulted in rapid immune exclusion of pilus-expressing pneumococci. Our findings predict that immune exclusion would select for non-piliated isolates in individuals who acquired RrgB-specific sIgA from prior episodes of colonization with piliated strains. Accordingly, genomic data comparing isolates carried by mothers and their children showed that mothers are less likely to be colonized with pilus-expressing strains. Our study provides a specific example of immune exclusion involving naturally-acquired antibody in the human host, a major factor driving pneumococcal adaptation.
Ulrike Binsker, John A. Lees, Alexandria J. Hammond, Jeffrey N. Weiser
Glucocorticoids (GCs) are a central component of therapy for patients with T-cell acute lymphoblastic leukemia (T-ALL) and while resistance to GCs is a strong negative prognostic indicator in T-ALL, mechanisms of GC resistance remain poorly understood. Using diagnostic samples from patients enrolled on the frontline Children’s Oncology Group (COG) T-ALL clinical trial AALL1231, we demonstrated that one-third of primary T-ALLs were resistant to GCs when cultured in the presence of interleukin-7 (IL7), a cytokine that is critical for normal T-cell function and that plays a well-established role in leukemogenesis. We demonstrated that in these T-ALLs and in distinct populations of normal developing thymocytes, GCs paradoxically induced their own resistance by promoting upregulation of IL7 receptor (IL7R) expression. In the presence of IL7, this augmented downstream signal transduction resulting in increased STAT5 transcriptional output and upregulation of the pro-survival protein BCL-2. Taken together, we demonstrated that IL7 mediates an intrinsic and physiologic mechanism of GC resistance in normal thymocyte development that is retained during leukemogenesis in a subset of T-ALLs and is reversible with targeted inhibition of the IL7R/JAK/STAT5/BCL-2 axis.
Lauren K. Meyer, Benjamin J. Huang, Cristina Delgado-Martin, Ritu P. Roy, Aaron Hechmer, Anica M. Wandler, Tiffaney L. Vincent, Paolo Fortina, Adam B. Olshen, Brent L. Wood, Terzah M. Horton, Kevin M. Shannon, David T. Teachey, Michelle L. Hermiston