The virulence of intracellular pathogens relies largely on the ability to survive and replicate within phagocytes, but also on the release and transfer into new host cells. Such cell-to-cell transfer could represent a target for counteracting microbial pathogenesis. However, our understanding of the underlying cellular and molecular processes remains woefully insufficient. Using intravital 2-photon microscopy of caspase-3 activation in the Leishmania major (L. major)-infected live skin, we show increased apoptosis in cells infected by the parasite. Also, transfer of the parasite to new host cells occurred directly without a detectable extracellular state, and was associated with concomitant uptake of cellular material from the original host cell. These in vivo findings were fully recapitulated in infections of isolated human phagocytes. Furthermore, we observed that high pathogen proliferation increased cell death in infected cells, and long-term residency within an infected host cell was only possible for slowly proliferating parasites. Our results therefore suggest that L. major drives its own dissemination to new phagocytes by inducing host cell death in a proliferation-dependent manner.
Iris Baars, Moritz Jaedtka, Leon-Alexander Dewitz, Yan Fu, Tobias Franz, Juliane Mohr, Patricia Gintschel, Hannes Berlin, Angelina Degen, Sandra Freier, Stefan M. Rygol, Burkhart Schraven, Sascha Kahlfuss, Ger van Zandbergen, Andreas J. Müller
BACKGROUND. Antibody-based therapies for respiratory viruses are of increasing importance. The INSIGHT006 trial administered anti-influenza hyperimmune intravenous immunoglobulin (Flu-IVIG) to patients hospitalised with influenza. Flu-IVIG treatment improved outcomes in patients with influenza B but showed no benefit for influenza A. METHODS. To probe potential mechanisms of Flu-IVIG utility, sera collected from patients hospitalised with influenza A or B viruses (IAV or IBV) were analysed for antibody isotype/subclass and Fc-gamma receptor (FcgR) binding by ELISA, bead-based multiplex and NK cell activation assays. RESULTS. Influenza-specific FcgR binding antibodies were elevated in Flu-IVIG infused IBV- and IAV-infected patients. In IBV-infected participants (n = 62), increased IgG3 and FcgR binding were associated with more favourable outcomes. Flu-IVIG therapy also improved the odds of a more favourable outcome in patients with low levels of anti-IBV Fc-functional antibody. Higher FcgR binding antibody was associated with less favourable outcomes in IAV-infected patients (n = 50), and Flu-IVIG worsened the odds of a favourable outcome in participants with low levels of anti-IAV Fc-functional antibody. CONCLUSION. These detailed serological analyses provide insights into antibody features and mechanisms required for a successful humoral response against influenza, suggesting that IBV-specific, but not IAV-specific, antibodies with Fc-mediated functions may assist in improving influenza outcome. This work will inform development of improved influenza immunotherapies. TRIAL REGISTRATION. ClinicalTrials.gov NCT02287467 FUNDING SOURCES. Funding for this research was provided by Subcontract 13XS134 under Leidos Biomedical Research Prime Contract HHSN261200800001E and HHSN261201500003I, NCI/NIAID.
Hillary A. Vanderven, Deborah N. Wentworth, Win Min Han, Heidi Peck, Ian G. Barr, Richard T. Davey, Jr., John H. Beigel, Dominic E. Dwyer, Mamta K. Jain, Brian Angus, Christian T. Brandt, Analia Mykietiuk, Matthew G. Law, James D. Neaton, Stephen J. Kent
Pregnancy poses a greater risk for severe COVID-19; however, underlying immunological changes associated with SARS-CoV-2 during pregnancy are poorly understood. We defined immune responses to SARS-CoV-2 in unvaccinated pregnant and nonpregnant women with acute and convalescent COVID-19, quantifying 217 immunological parameters. Humoral responses to SARS-CoV-2 were similar in pregnant and nonpregnant women, although our systems serology approach revealed distinct antibody and FcγR profiles between pregnant and nonpregnant women. Cellular analyses demonstrated marked differences in NK cell and unconventional T cell activation dynamics in pregnant women. Healthy pregnant women displayed preactivated NK cells and γδ T cells when compared with healthy nonpregnant women, which remained unchanged during acute and convalescent COVID-19. Conversely, nonpregnant women had prototypical activation of NK and γδ T cells. Activation of CD4+ and CD8+ T cells and T follicular helper cells was similar in SARS-CoV-2–infected pregnant and nonpregnant women, while antibody-secreting B cells were increased in pregnant women during acute COVID-19. Elevated levels of IL-8, IL-10, and IL-18 were found in pregnant women in their healthy state, and these cytokine levels remained elevated during acute and convalescent COVID-19. Collectively, we demonstrate perturbations in NK cell and γδ T cell activation in unvaccinated pregnant women with COVID-19, which may impact disease progression and severity during pregnancy.
Jennifer R. Habel, Brendon Y. Chua, Lukasz Kedzierski, Kevin J. Selva, Timon Damelang, Ebene R. Haycroft, Thi H.O. Nguyen, Hui-Fern Koay, Suellen Nicholson, Hayley A. McQuilten, Xiaoxiao Jia, Lilith F. Allen, Luca Hensen, Wuji Zhang, Carolien E. van de Sandt, Jessica A. Neil, Katherine Pragastis, Jillian S.Y. Lau, Jaycee Jumarang, E. Kaitlynn Allen, Fatima Amanant, Florian Krammer, Kathleen M. Wragg, Jennifer A. Juno, Adam K. Wheatley, Hyon-Xhi Tan, Gabrielle Pell, Susan Walker, Jennifer Audsley, Arnold Reynaldi, Irani Thevarajan, Justin T. Denholm, Kanta Subbarao, Miles P. Davenport, P. Mark Hogarth, Dale I. Godfrey, Allen C. Cheng, Steven Y.C. Tong, Katherine Bond, Deborah A. Williamson, James H. McMahon, Paul G. Thomas, Pia S. Pannaraj, Fiona James, Natasha E. Holmes, Olivia C. Smibert, Jason A. Trubiano, Claire L. Gordon, Amy W. Chung, Clare L. Whitehead, Stephen J. Kent, Martha Lappas, Louise C. Rowntree, Katherine Kedzierska
Emerging data indicates an association between environmental heavy metal exposure and lung disease, including lower respiratory tract infections (LRTIs). Here, we show by single cell RNA-sequencing an increase in Pparg gene expression in lung macrophages from mice exposed to cadmium and/or infected with S. pneumoniae. However, the heavy metal cadmium or infection mediated an inhibitory post-translational modification of peroxisome proliferator-activated receptor ɣ (PPARɣ) to exacerbate LRTIs. Cadmium and infection increased ERK activation to regulate PPARɣ degradation in monocyte-derived macrophages. Mice harboring a conditional deletion of Pparg in monocyte-derived macrophages had more severe S. pneumoniae infection after cadmium exposure, showed greater lung injury, and had increased mortality. Inhibition of ERK activation with BVD-523 protected mice from lung injury after cadmium exposure or infection. Moreover, subjects residing in areas of high air cadmium levels had increased cadmium concentration in their BAL fluid, increased barrier dysfunction, and showed PPARɣ inhibition that was mediated, at least in part, by ERK activation in isolated BAL cells. These observations suggest that impaired activation of PPARɣ in monocyte-derived macrophages exacerbates lung injury and the severity of LRTIs.
Jennifer L. Larson-Casey, Shanrun Liu, Jennifer M. Pyles, Suzanne E. Lapi, Komal Saleem, Veena B. Antony, Manuel Lora Gonzalez, David K. Crossman, A. Brent Carter
Sepsis is a lethal syndrome characterized by systemic inflammation and abnormal coagulation. Despite therapeutic advances, sepsis mortality remains substantially high. Herein, we investigated the role of the plasminogen/plasmin (Plg/Pla) system during sepsis. Plasma levels of Plg were significantly lower in mice subjected to severe compared with non-severe sepsis, whereas systemic levels of IL-6, a marker of sepsis severity, were higher in severe sepsis. Plg levels correlated negatively with IL-6 in both septic mice and patients while the plasminogen activator inhibitor-1 (PAI-1) correlated positively with IL-6. Plg deficiency render mice susceptible to non-severe sepsis induced by cecal ligation and puncture (CLP), showing higher numbers of neutrophils and M1 macrophages, liver fibrin(ogen) deposition, lower efferocytosis and increased IL-6 and neutrophil extracellular traps (NETs) release associated with organ damage. Conversely, inflammatory features, fibrin(ogen) and organ damage were substantially reduced, and efferocytosis was increased by exogenous Pla given during CLP and LPS-induced endotoxemia. Plg or Pla protected mice from sepsis-induced lethality and enhanced the protective effect of antibiotics. Mechanistically, Plg/Pla afforded protection was associated with regulation of NET release, requiring Pla-protease activity and lysine binding sites. Altogether, Plg/Pla are important host protective players during sepsis, controlling local and systemic inflammation and collateral organ damage.
Juliana P. Vago, Isabella Zaidan, Luiza O. Perucci, Larissa F. Brito, Lívia C.R. Teixeira, Camila M.S. Silva, Thaís C. Miranda, Eliza M. Melo, Alexandre S. Bruno, Celso M. Queiroz-Junior, Michelle A. Sugimoto, Luciana P. Tavares, Laís C. Grossi, Isabela N. Borges, Nagyung Baik, André Talvani, Raphael G. Ferreira, José C. Alves-Filho, Vandack Nobre, Mauro M. Teixeira, Robert J. Parmer, Lindsey A. Miles, Lirlândia P. Sousa
BACKGROUND. After its introduction as standard-of-care for severe COVID-19, dexamethasone has been administered to a large number of patients globally. Detailed knowledge of its impact on the cellular and humoral immune response to SARS-CoV-2 remains scarce. METHODS. We included immunocompetent individuals with 1) mild COVID-19, 2) severe COVID-19 before introduction of dexamethasone treatment, and 3) severe COVID-19 infection treated with dexamethasone from prospective observational cohort studies at Charité-Universitätsmedizin Berlin, Germany. We analyzed SARS-CoV-2 spike-reactive T cells, spike-specific IgG titers as well as serum neutralizing activity against B.1.1.7, B.1.617.2 in samples ranging from two weeks to six months post infection. We also analyzed BA.2 neutralization in sera after booster immunization. RESULTS. Patients with severe COVID-19 and dexamethasone treatment had lower T cell and antibody responses to SARS-CoV-2 compared to patients without dexamethasone treatment in the early phase of disease, which converged in both groups before six months post infection and also post-immunization. Patients with mild COVID-19 had a comparatively lower T cell and antibody response than patients with severe disease, including a lower response to booster-immunization during convalescence. CONCLUSION. Dexamethasone treatment is associated with short-term reduction of T cell and antibody response in severe COVID-19 when compared to the non-treated group, but this difference evens out six months after infection. We confirm higher cellular and humoral immune responses in patients after severe versus mild COVID-19 infection and the concept of improved hybrid immunity upon immunization. TRIAL REGISTRATION.: n/aFunding: Berlin Institute of Health, German Federal Ministry of Education and German Federal Institute for Drugs and Medical Devices
Charlotte Thibeault, Lara Bardtke, Kanika Vanshylla, Veronica Cristianzano, Kirsten A. Eberhardt, Paula Stubbemann, David Hillus, Pinkus Tober-Lau, Parnika Mukherjee, Friederike Münn, Lena J Lippert, Elisa T. Helbig, Tilman Lingscheid, Fridolin Steinbeis, Mirja Mittermaier, Martin Witzenrath, Thomas Zoller, Florian Klein, Leif E. Sander, Florian Kurth
Sosuga virus (SOSV) is a recently discovered paramyxovirus with a single known human case of disease. There has been little laboratory research on SOSV pathogenesis or immunity, and no approved therapeutics or vaccines are available. Here, we report the discovery of human monoclonal antibodies (mAbs) from the circulating memory B cells of the only known human case and survivor of SOSV infection. We isolated six mAbs recognizing the functional attachment protein hemagglutinin-neuraminidase (HN) and 18 mAbs against the fusion (F) protein. The anti-HN mAbs all target the globular head of the HN protein and can be organized into 4 competition-binding groups that exhibit epitope diversity. The anti-F mAbs can be divided into pre- or postfusion conformation-specific categories and further into 8 competition-binding groups. The only antibody in the panel that did not display neutralization activity was the single, postfusion-specific anti-F mAb. Most of the anti-HN mAbs were more potently neutralizing than the anti-F mAbs, with mAbs in one of the HN competition-binding groups possessing ultra-potent (<1 ng/mL) half maximal inhibitory (IC50) virus neutralization values. These findings provide insight into the molecular basis for human antibody recognition of paramyxovirus surface proteins and the mechanisms of SOSV neutralization.
Helen M. Parrington, Nurgun Kose, Erica Armstrong, Laura S. Handal, Summer Diaz, Joseph Reidy, Jinhui Dong, Guillaume B.E. Stewart-Jones, Punya Shrivastava-Ranjan, Shilpi Jain, César G. Albariño, Robert H. Carnahan, James E. Crowe
The widespread presence of autoantibodies in acute infection with SARS-CoV-2 is increasingly recognized, but the prevalence of autoantibodies in non–SARS-CoV-2 infections and critical illness has not yet been reported. We profiled IgG autoantibodies in 267 patients from 5 independent cohorts with non–SARS-CoV-2 viral, bacterial, and noninfectious critical illness. Serum samples were screened using Luminex arrays that included 58 cytokines and 55 autoantigens, many of which are associated with connective tissue diseases (CTDs). Samples positive for anti-cytokine antibodies were tested for receptor blocking activity using cell-based functional assays. Anti-cytokine antibodies were identified in > 50% of patients across all 5 acutely ill cohorts. In critically ill patients, anti-cytokine antibodies were far more common in infected versus uninfected patients. In cell-based functional assays, 11 of 39 samples positive for select anti-cytokine antibodies displayed receptor blocking activity against surface receptors for Type I IFN, GM-CSF, and IL-6. Autoantibodies against CTD-associated autoantigens were also commonly observed, including newly detected antibodies that emerged in longitudinal samples. These findings demonstrate that anti-cytokine and autoantibodies are common across different viral and nonviral infections and range in severity of illness.
Allan Feng, Emily Y. Yang, Andrew Reese Moore, Shaurya Dhingra, Sarah Esther Chang, Xihui Yin, Ruoxi Pi, Elisabeth K.M. Mack, Sara Völkel, Reinhard Geßner, Margrit Gündisch, Andreas Neubauer, Harald Renz, Sotirios Tsiodras, Paraskevi C. Fragkou, Adijat A. Asuni, Joseph E. Levitt, Jennifer G. Wilson, Michelle Leong, Jennifer H. Lumb, Rong Mao, Kassandra Pinedo, Jonasel Roque, Christopher M. Richards, Mikayla Stabile, Gayathri Swaminathan, Maria L. Salagianni, Vasiliki Triantafyllia, Wilhelm Bertrams, Catherine A. Blish, Jan E. Carette, Jennifer Frankovich, Eric Meffre, Kari Christine Nadeau, Upinder Singh, Taia T. Wang, Eline T. Luning Prak, Susanne Herold, Evangelos Andreakos, Bernd Schmeck, Chrysanthi Skevaki, Angela J. Rogers, Paul J. Utz
The expression of indoleamine 2,3-dioxygenase (IDO), a robust immunosuppressant, is significantly induced in macaque tuberculosis (TB) granulomas, where it is expressed on IFN-responsive macrophages and myeloid-derived suppressor cells. IDO expression is also highly induced in human TB granulomas, and products of its activity are detected in patients with TB. In vivo blockade of IDO activity resulted in the reorganization of the granuloma with substantially greater T cells being recruited to the core of the lesions. This correlated with better immune control of TB and reduced lung M. tuberculosis burdens. To study if the IDO blockade strategy can be translated to a bona fide host-directed therapy in the clinical setting of TB, we studied the effect of IDO inhibitor 1-methyl-d-tryptophan adjunctive to suboptimal anti-TB chemotherapy. While two-thirds of controls and one-third of chemotherapy-treated animals progressed to active TB, inhibition of IDO adjunctive to the same therapy protected macaques from TB, as measured by clinical, radiological, and microbiological attributes. Although chemotherapy improved proliferative T cell responses, adjunctive inhibition of IDO further enhanced the recruitment of effector T cells to the lung. These results strongly suggest the possibility that IDO inhibition can be attempted adjunctive to anti-TB chemotherapy in clinical trials.
Bindu Singh, Chivonne Moodley, Dhiraj K. Singh, Ruby A. Escobedo, Riti Sharan, Garima Arora, Shashank R. Ganatra, Vinay Shivanna, Olga Gonzalez, Shannan Hall-Ursone, Edward J. Dick Jr., Deepak Kaushal, Xavier Alvarez, Smriti Mehra
Cystic fibrosis (CF) is characterized by chronic bacterial infections leading to progressive bronchiectasis and respiratory failure. Pseudomonas aeruginosa (Pa) is the predominant opportunistic pathogen infecting the CF airways. The guanine nucleotide exchange factor Vav3 plays a critical role in Pa adhesion to the CF airways by inducing luminal fibronectin deposition that favors bacteria trapping. Here we report that Vav3 overexpression in CF is caused by upregulation of the mRNA-stabilizing protein HuR. We found that HuR accumulates in the cytoplasm of CF airway epithelial cells, binds to and stabilizes Vav3 mRNA. Interestingly, disruption of HuR-Vav3 mRNA interaction improved the CF epithelial integrity, inhibited the formation of the fibronectin-made bacterial docking platforms and prevented Pa adhesion to the CF airway epithelium. These findings indicate that targeting HuR represents a promising anti-adhesive approach in CF to prevent initial stages of Pa infection in a context of emergence of multidrug resistant pathogens.
Mehdi Badaoui, Cyril Sobolewski, Alexandre Luscher, Marc Bacchetta, Thilo Köhler, Christian van Delden, Michelangelo Foti, Marc Chanson
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