Posttranslational modifications are a common feature of proteins associated with neurodegenerative diseases including prion protein (PrPC), tau and α-synuclein. Alternative self-propagating protein states or strains give rise to different disease phenotypes and display strain-specific subsets of posttranslational modifications. The relationships between strain-specific structure, posttranslational modifications and disease phenotype are poorly understood. We previously reported that among hundreds of PrPC sialoglycoforms expressed by a cell, individual prion strains recruited PrPC molecules selectively, according to the sialylation status of their N-linked glycans. Here we report that transmission of a prion strain to a new host is accompanied by a dramatic shift in the selectivity of recruitment of PrPC sialoglycoforms giving rise to PrPSc with a unique sialoglycoform signature and disease phenotype. The newly emerged strain has the shortest incubation time to disease, is characterized by a colocalization of PrPSc with microglia and a very profound proinflammatory response, features that are linked to a unique sialoglycoform composition of PrPSc. The current work provides experimental support for a hypothesis that strain-specific patterns of PrPSc sialoglycoforms formed as a result of selective recruitment dictate strain-specific disease phenotypes. This work suggests a causative relationship between a strain-specific structure, posttranslational modifications and disease phenotype.
Natallia Makarava, Jennifer Chen-Yu Chang, Kara Molesworth, Ilia V. Baskakov
FTY720 (Gilenya, Novartis), is a treatment for relapsing remitting multiple sclerosis (MS). It is an analog of sphingosine-1-phosphate (S1P) and targets S1P receptors 1,3,4, and 5. Recent reports indicate an association between long term exposure to FTY720 and cases of cryptococcal infection. Here, we studied the effect of FTY720 and its derivative, BAF312 (Mayzent, Novartis), which only target S1P receptors 1 and 5, in a mouse model of cryptococcal infection. We found that treatment with FTY720, but not with BAF312, lead to decreased survival and increased organ burden in mouse cryptococcal granulomas. Both FTY720 and BAF312 caused a profound CD4+ and CD8+ T cell depletion in blood and lungs but only treatment with FTY720 lead to cryptococcal reactivation. Treatment with FTY720, but not with BAF312, was associated with disorganization of macrophages and with a M2 polarization at the granuloma site. In a cell system, FTY720 decreased phagocytosis and production of reactive oxygen species by macrophages, a phenotype recapitulated in the S1pr3-/- knockout macrophages. Our results suggest that FTY720 reactivates cryptococcosis from the granuloma through a S1P receptor 3-mediated mechanism and support the rationale for development of more specific receptor modulators for therapeutic use of MS.
Arielle M. Bryan, Jeehyun Karen You, Travis McQuiston, Cristina Lazzarini, Zhijuan Qiu, Brian S. Sheridan, Barbara Nuesslein-Hildesheim, Maurizio Del Poeta
Background: Coronavirus disease 19 (COVID-19) is an emerging infectious disease caused by SARS-CoV-2. Anti-viral immune response is crucial to achieve pathogen clearance, however in some patients an excessive and aberrant host immune response can lead to an acute respiratory distress syndrome. The comprehension of the mechanisms that regulate pathogen elimination, immunity, and pathology is essential to better characterize disease progression and widen the spectrum of therapeutic options. Methods: We performed a flow cytometric characterization of immune cells subsets from 30 COVID-19 patients and correlated these data with clinical outcomes. Results: COVID-19 patients showed decreased numbers of circulating T, B and NK cells, and exhibited a skewing of CD8+ T cells towards a terminally differentiated/senescent phenotype. In agreement, T CD4+, T CD8+ but also NK cells displayed reduced anti-viral cytokine production capability. Moreover, a reduced cytotoxic potential was identified in COVID-19 patients, particularly in those that required intensive care. The latter group of patients showed also increased serum IL-6 levels, that correlated to the frequency of granzyme-expressing NK cells. Off-label treatment with tocilizumab restored the cytotoxic potential of NK cells. Conclusion: In conclusion, the association between IL-6 serum levels and the impairment of cytotoxic activity suggests the possibility that targeting this cytokine may restore anti-viral mechanisms. Funding: This study was supported by funds of Dept. of Experimental and Clinical Medicine of University of Florence (ex-60%) derived from Ministero dell’Istruzione, dell’Università e della Ricerca (Italy).
Alessio Mazzoni, Lorenzo Salvati, Laura Maggi, Manuela Capone, Anna Vanni, Michele Spinicci, Jessica Mencarini, Roberto Caporale, Benedetta Peruzzi, Alberto Antonelli, Michele Trotta, Lorenzo Zammarchi, Luca Ciani, Leonardo Gori, Chiara Lazzeri, Andrea Matucci, Alessandra Vultaggio, Oliviero Rossi, Fabio Almerigogna, Paola Parronchi, Paolo Fontanari, Federico Lavorini, Adriano Peris, Gian Maria Rossolini, Alessandro Bartoloni, Sergio Romagnani, Francesco Liotta, Francesco Annunziato, Lorenzo Cosmi
The microbiome provides resistance to infection. However, mechanisms for this are poorly understood. Here we demonstrate in a murine model that colonization with the intestinal bacterium Clostridium scindens provided protection from Entamoeba histolytica colitis via innate immunity. Introduction of C. scindens into the gut microbiota epigenetically altered and expanded bone marrow granulocyte-monocyte-progenitors (GMPs) and resulted in increased intestinal neutrophils with subsequent challenge with E. histolytica. Introduction of C. scindens alone was sufficient to expand GMPs in gnotobiotic mice. Adoptive transfer of bone-marrow from C. scindens colonized-mice into naïve-mice protected against amebic colitis and increased intestinal neutrophils. Children without E. histolytica diarrhea also had a higher abundance of Lachnoclostridia. Because of the known ability of the Lachnoclostridia C. scindens to metabolize the bile salt cholate, we measured deoxycholate and discovered that it was increased in the sera of C. scindens colonized specific pathogen free and gnotobiotic mice, as well as in children protected from amebiasis. Administration of deoxycholate alone (in the absence of C. scindens) increased GMPs and provided protection from amebiasis. We have discovered a mechanism by which C. scindens and the microbially-metabolized bile salt deoxycholic acid alter hematopoietic precursors and provide innate protection from later infection with Entamoeba histolytica.
Stacey L. Burgess, Jhansi L. Leslie, Md. Jashim Uddin, David Noah Oakland, Carol A. Gilchrist, G. Brett Moreau, Koji Watanabe, Mahmoud M. Saleh, Morgan Simpson, Brandon A. Thompson, David T. Auble, Stephen D. Turner, Natasa Giallourou, Jonathan Swann, Zhen Pu, Jennie Z. Ma, Rashidul Haque, William A. Petri, Jr.
Patients with respiratory syncytial virus (RSV) infection exhibit enhanced susceptibility to subsequent pneumococcal infections. However, the underlying mechanisms involved in this increased susceptibility remain unclear. Here, we identified potentially novel cellular and molecular cascades triggered by RSV infection to exacerbate secondary pneumococcal pneumonia. RSV infection stimulated the local production of growth arrest–specific 6 (Gas6). The Gas6 receptor Axl was crucial for attenuating pneumococcal immunity in that the Gas6/Axl blockade fully restored antibacterial immunity. Mechanistically, Gas6/Axl interaction regulated the conversion of alveolar macrophages from an antibacterial phenotype to an M2-like phenotype that did not exhibit antibacterial activity, and the attenuation of caspase-1 activation and IL-18 production in response to pneumococcal infection. The attenuated IL-18 production failed to drive both NK cell–mediated IFN-γ production and local NO and TNF-α production, which impair the control of bacterial infection. Hence, the RSV-mediated Gas6/Axl activity attenuates the macrophage-mediated protection against pneumococcal infection. The Gas6/Axl axis could be a potentially novel therapeutic target for RSV-associated secondary bacterial infection.
Takehiko Shibata, Airi Makino, Ruiko Ogata, Shigeki Nakamura, Toshihiro Ito, Kisaburo Nagata, Yoshihiko Terauchi, Taku Oishi, Mikiya Fujieda, Yoshimasa Takahashi, Manabu Ato
BACKGROUND Novel therapeutic approaches are critically needed for Staphylococcus aureus bloodstream infections (BSI), particularly for methicillin-resistant S. aureus (MRSA). Exebacase, a first-in-class antistaphylococcal lysin, is a direct lytic agent that is rapidly bacteriolytic, eradicates biofilms, and synergizes with antibiotics. METHODS In this superiority-design study, we randomly assigned 121 patients with S. aureus BSI/endocarditis to receive a single dose of exebacase or placebo. All patients received standard-of-care antibiotics. The primary efficacy endpoint was clinical outcome (responder rate) at Day 14. RESULTS Clinical responder rates at Day 14 were 70.4% and 60.0% in the exebacase + antibiotics and antibiotics alone groups, respectively (difference=10.4, 90% CI [-6.3, 27.2], p-value=0.31), and were 42.8 percentage points higher in the pre-specified exploratory MRSA subgroup (74.1% vs. 31.3%, difference=42.8, 90% CI [14.3, 71.4], ad hoc p value=0.01). Rates of adverse events (AEs) were similar in both groups. No AEs of hypersensitivity to exebacase were reported. Thirty-day all-cause mortality rates were 9.7% and 12.8% in the exebacase + antibiotics and antibiotics alone groups, respectively, with a notable difference in MRSA (3.7% vs. 25.0%, difference= –21.3, 90% CI [-45.1, 2.5], ad hoc p-value=0.06). Among MRSA patients in the United States, median length-of-stay was 4-days shorter and 30-day hospital readmission rates were 48 percentage points lower in the exebacase-treated group compared with antibiotics alone. CONCLUSIONS This study establishes proof-of-concept for exebacase and direct lytic agents as potential therapeutics and supports conduct of a confirmatory study focused on exebacase to treat MRSA BSI.
Vance G. Fowler, Jr., Anita F. Das, Joy Lipka-Diamond, Raymond Schuch, Roger Pomerantz, Luis Jáuregui-Peredo, Adam Bressler, David C. Evans, Gregory J. Moran, Mark E. Rupp, Robert A. Wise, G. Ralph Corey, Marcus Zervos, Pamela S. Douglas, Cara Cassino
BACKGROUND. Since December 2019, an outbreak of Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, and is now becoming a global threat. We aimed to delineate and compare the immunologic features of severe and moderate COVID-19. METHODS. In this retrospective study, the clinical and immunologic characteristics of 21 patients (17 male and 4 female) with COVID-19 were analyzed. These patients were classified as severe (11 cases) and moderate (10 cases) according to the Guidelines released by the National Health Commission of China. RESULTS. The median age of severe and moderate cases was 61.0 and 52.0 years, respectively. Common clinical manifestations included fever, cough and fatigue. Compared to moderate cases, severe cases more frequently had dyspnea, lymphopenia, and hypoalbuminemia, with higher levels of alanine aminotransferase, lactate dehydrogenase, C-reactive protein, ferritin and D-dimer as well as markedly higher levels of IL-2R, IL-6, IL-10, and TNF-α. Absolute number of T lymphocytes, CD4+T and CD8+T cells decreased in nearly all the patients, and were markedly lower in severe cases (294.0, 177.5 and 89.0 × 106/L) than moderate cases (640.5, 381.5 and 254.0 × 106/L). The expressions of IFN-γ by CD4+T cells tended to be lower in severe cases (14.1%) than moderate cases (22.8%). CONCLUSION. The SARS-CoV-2 infection may affect primarily T lymphocytes particularly CD4+T and CD8+ T cells, resulting in decrease in numbers as well as IFN-γ production. These potential immunological markers may be of importance due to their correlation with disease severity in COVID-19.
Guang Chen, Di Wu, Wei Guo, Yong Cao, Da Huang, Hongwu Wang, Tao Wang, Xiaoyun Zhang, Huilong Chen, Haijing Yu, Xiaoping Zhang, Minxia Zhang, Shiji Wu, Jianxin Song, Tao Chen, Meifang Han, Shusheng Li, Xiaoping Luo, Jianping Zhao, Qin Ning
As treatment of the early, inflammatory phase of sepsis improves, post-sepsis immunosuppression and secondary infection have increased in importance. How early inflammation drives immunosuppression remains unclear. Although IFNγ typically helps microbial clearance, we found that increased plasma IFNγ in early clinical sepsis was associated with the later development of secondary Candida infection. Consistent with this observation, we found that exogenous IFNγ suppressed macrophage phagocytosis of zymosan in vivo, and antibody blockade of IFNγ after endotoxemia improved survival of secondary candidemia. Transcriptomic analysis of innate lymphocytes during endotoxemia suggested that NKT cells drove IFNγ production by NK cells via mTORC1. Activation of iNKT cells with glycolipid antigen drove immunosuppression. Deletion of iNKT cells in Cd1d-/- mice or inhibition of mTOR by rapamycin reduced immunosuppression and susceptibility to secondary Candida infection. Thus, although rapamycin is typically an immunosuppressive medication, in the context of sepsis, rapamycin has the opposite effect. These results implicated a NKT cell-mTOR-IFNγ axis in immunosuppression following endotoxemia or sepsis. In summary, in vivo iNKT cells activated mTORC1 in NK cells to produce IFNγ , which worsened macrophage phagocytosis, clearance of secondary Candida infection and mortality.
Edy Y. Kim, Hadas Ner-Gaon, Jack Varon, Aidan M. Cullen, Jingyu Guo, Jiyoung Choi, Diana Barragan-Bradford, Angelica Higuera, Mayra Pinilla-Vera, Samuel A.P. Short, Antonio J. Arciniegas-Rubio, Tomoyoshi Tamura, David E. Leaf, Rebecca M. Baron, Tal Shay, Michael B. Brenner
Neutrophil accumulation is associated with lung pathology during active tuberculosis (ATB). However, the molecular mechanism(s) by which neutrophils accumulate in the lung and contribute to TB immunopathology is not fully delineated. Using the well-established mouse model of TB, our new data provides evidence that the alarmin S100A8/A9 mediates neutrophil accumulation during progression to chronic TB. Depletion of neutrophils or S100A8/A9 deficiency resulted in improved Mycobacterium tuberculosis (Mtb) control during chronic but not acute TB. Mechanistically, we demonstrate that following Mtb infection, S100A8/A9 expression is required for upregulation of the integrin molecule CD11b specifically on neutrophils, mediating their accumulation during chronic TB disease. These findings are further substantiated by increased expression of S100A8 and S100A9 mRNA in whole blood in human TB progressors when compared to non-progressors, and rapidly decreased S100A8/A9 protein levels in the serum upon TB treatment. Furthermore, we demonstrate that S100A8/A9 serum levels along with chemokines are useful in distinguishing between ATB and asymptomatic Mtb-infected latent individuals. Thus, our results support targeting S100A8/A9 pathways as host-directed therapy for TB.
Ninecia R. Scott, Rosemary V. Swanson, Noor Al-Hammadi, Racquel Domingo-Gonzalez, Javier Rangel-Moreno, Belinda A. Kriel, Allison N. Bucsan, Shibali Das, Mushtaq Ahmed, Smriti Mehra, Puthayalai Treerat, Alfredo Cruz-Lagunas, Luis Jimenez-Alvarez, Marcela Muñoz-Torrico, Karen Bobadilla-Lozoya, Thomas Vogl, Gerhard Walzl, Nelita du Plessis, Deepak Kaushal, Thomas Scriba, Joaquin Zuñiga, Shabaana Khader
Mycobacterium tuberculosis (Mtb) has co-evolved with humans for millennia and developed multiple mechanisms to evade host immunity. Restoring host immunity in order to improve outcomes and potentially shorten existing therapy will require identifying the full complement by which host immunity is inhibited. Perturbing host DNA methylation is a mechanism induced by chronic infections such as HIV, HPV, LCMV and schistosomiasis to evade host immunity. Here, we evaluated the DNA methylation status of TB patients and their asymptomatic household contacts demonstrating that TB patients have DNA hyper-methylation of the IL-2-STAT5, TNF-NF-ϰB and IFN-γ signaling pathways. By MSRE-qPCR, multiple genes of the IL-12-IFN-γ signaling pathway (IL12B, IL12RB2, TYK2, IFNGR1, JAK1 and JAK2) were hyper-methylated in TB patients. The DNA hyper-methylation of these pathways is associated with decreased immune responsiveness with decreased mitogen-induced upregulation of IFN-γ, TNF, IL-6, CXCL9, CXCL10 and IL-1β production. The DNA hyper-methylation of the IL-12-IFN-γ pathway was associated with decreased IFN-γ induced gene expression and decreased IL-12 inducible up-regulation of IFN-γ. This work demonstrates that immune cells from TB patients are characterized by DNA hyper-methylation of genes critical to mycobacterial immunity resulting in decreased mycobacteria-specific and non-specific immune responsiveness.
Andrew DiNardo, Kimal Rajapakshe, Tomoki Nishiguchi, Godwin Mtetwa, Sandra L. Grimm, Qiniso Dlamini, Jaquiline Kahari, Sanjana Mahapatra, Alexander W. Kay, Gugu Maphalala, Emily M. Mace, George Makedonas, Jeffrey D. Cirillo, Mihai Netea, Reinout van Crevel, Cristian Coarfa, Anna M. Mandalakas
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