Infectious disease
Abstract
Recognition of pathogen-associated molecular patterns can trigger the IRE1α arm of the endoplasmic reticulum (ER) stress response in innate immune cells. This process maintains ER homeostasis and also coordinates diverse immunomodulatory programs during bacterial and viral infections. However, the role of innate IRE1α signaling in response to fungal pathogens remains elusive. Here, we report that systemic infection with the human opportunistic fungal pathogen Candida albicans induces proinflammatory IRE1α hyperactivation in myeloid cells that leads to fatal kidney immunopathology. Mechanistically, simultaneous activation of the TLR/IL-1R adaptor protein MyD88 and the C-type lectin receptor Dectin-1 by C. albicans induced NADPH oxidase-driven generation of reactive oxygen species that caused ER stress and IRE1α-dependent overexpression of key inflammatory mediators such as IL-1β, IL-6, CCL5, PGE2 and TNFα. Selective ablation of IRE1α in leukocytes, or treatment with an IRE1α pharmacological inhibitor, mitigated kidney inflammation and prolonged the survival of mice with systemic C. albicans infection. Therefore, controlling IRE1α hyperactivation may be useful for impeding the immunopathogenic progression of disseminated candidiasis.
Authors
Deepika Awasthi, Sahil Chopra, Byuri A. Cho, Alexander Emmanuelli, Tito A. Sandoval, Sung-Min Hwang, Chang-Suk Chae, Camilla Salvagno, Chen Tan, Liliana Vasquez-Urbina, Jose J. Fernandez Rodriguez, Sara F. Santagostino, Takao Iwawaki, E. Alfonso Romero-Sandoval, Mariano Sanchez Crespo, Diana K. Morales, Iliyan D. Iliev, Tobias M. Hohl, Juan R. Cubillos-Ruiz
Abstract
There is no vaccine to protect from cryptosporidiosis, a leading cause of diarrhea in infants in low and middle income countries. Here we comprehensively identified parasite antigens associated with protection from reinfection. A Cryptosporidium protein microarray was constructed by in vitro transcription and translation of 1761 C. parvum, C. hominis or C. meleagridis antigens, including proteins with a signal peptide and/or a transmembrane domain. Plasma IgG and/or IgA from Bangladeshi children longitudinally followed for cryptosporidiosis from birth to three years of age, identified 233 seroreactive proteins. Seven of these were associated with protection from reinfection. These included Cp23 and Cp17, Gp900 and four additional antigens (CpSMP1, CpMuc8, CpCorA and CpCCDC1). Infection in the first year of life however often resulted in no detectable antigen-specific antibody response, and antibody responses, when detected, were (i) specific to the infecting parasite genotype, and (ii) decayed in the months post-infection. In conclusion humoral immune responses against specific parasite antigens were associated with acquired immunity. While antibody decay over time and parasite genotype-specificity may limit natural immunity, this work serves as a foundation for antigen selection for vaccine design.
Authors
Carol A. Gilchrist, Joseph J. Campo, Jozelyn V. Pablo, Jennie Z. Ma, Andy Teng, Amit Oberai, Adam D. Shandling, Masud Alam, Mamun Kabir, Abu S.G. Faruque, Rashidul Haque, William A. Petri Jr.
An allosteric inhibitor of sirtuin 2 deacetylase activity exhibits broad-spectrum antiviral activity
Abstract
Most drugs used to treat viral disease target a virus-coded product. They inhibit a single virus or virus family, and the pathogen can readily evolve resistance. Host-targeted antivirals can overcome these limitations. The broad-spectrum activity achieved by host targeting can be especially useful in combating emerging viruses and for treatment of diseases caused by multiple viral pathogens, such as opportunistic agents in immunosuppressed patients. We have developed a family of compounds that modulate sirtuin 2, an NAD+-dependent deacylase, and now report the properties of a member of that family, FLS-359. Biochemical and x-ray structural studies show that the drug binds to sirtuin 2 and allosterically inhibits its deacetylase activity. FLS-359 inhibits the growth of RNA and DNA viruses, including members of the coronavirus, orthomyxovirus, flavivirus, hepadnavirus, and herpesvirus families. FLS-359 acts at multiple levels to antagonize cytomegalovirus replication in fibroblasts, causing modest reductions in viral RNAs and DNA, together with a much greater reduction in infectious progeny, and it exhibits antiviral activity in humanized mouse models of infection. Our results highlight the potential of sirtuin 2 inhibitors as broad-spectrum antivirals and set the stage for further understanding of how host epigenetic mechanisms impact the growth and spread of viral pathogens.
Authors
Kathryn L. Roche, Stacy Remiszewski, Matthew J. Todd, John L. Kulp III, Liudi Tang, Alison V. Welsh, Ashley P. Barry, Chandrav De, William W. Reiley, Angela Wahl, J. Victor Garcia, Micah A. Luftig, Thomas Shenk, James R. Tonra, Eain A. Murphy, Lillian W. Chiang
Abstract
Sepsis remains a leading cause of human death and currently has no pathogenesis-specific therapy. Hampered progress is partly due to a lack of insight into deep mechanistic processes. In the last decade, deciphering the functions of small non-coding microRNAs (miRNAs) in sepsis pathogenesis became a dynamic research topic. To screen for new miRNA targets for sepsis therapeutics, we used human samples for miRNA array from peripheral blood mononuclear cells from sepsis patients and controls, blood samples from two cohorts of sepsis patients, and multiple animal models: mouse cecum ligation-puncture (CLP)-induced sepsis, mouse viral miRNA challenge, and baboon Gram-positive and Gram-negative sepsis models. miR-93-5p met the criteria for a therapeutic target, being overexpressed in baboons that died early after induction of sepsis, downregulated in humans who survived after sepsis, and correlated with negative clinical prognosticators for sepsis. Therapeutically, inhibiting miR-93-5p prolonged the overall survival of mice with CLP-induced sepsis, with a stronger effect in older mice. Mechanistically, anti-miR-93-5p therapy reduced inflammatory monocytes and increased circulating effector memory T cells, especially the CD4+ subset. AGO2-immunoprecipitation in miR-93-knockout T cells identified important regulatory receptors, such as CD28, as direct miR-93-5p target genes. In conclusion, miR-93-5p is a potential therapeutic target in sepsis through regulating both innate and adaptive immunity with possibly more benefit for the elderly than the young patients.
Authors
Mihnea P. Dragomir, Enrique Fuentes-Mattei, Melanie Winkle, Keishi Okubo, Recep Bayraktar, Erik Knutsen, Aiham Qdaisat, Meng Chen, Yongfeng Li, Masayoshi Shimizu, Lan Pang, Kevin Liu, Xiuping Liu, Simone Anfossi, Huanyu Zhang, Ines Koch, Anh M. Tran, Swati Mohapatra, Anh Ton, Mecit Kaplan, Matthew W. Anderson, Spencer J. Rothfuss, Robert Silasi, Ravi S. Keshari, Manuela Ferracin, Cristina Ivan, Cristian Rodriguez-Aguayo, Gabriel Lopez-Berestein, Constantin Georgescu, Pinaki P. Banerjee, Rafet Basar, Ziyi Li, David Horst, Catalin Vasilescu, Maria Teresa S. Bertilaccio, Katayoun Rezvani, Florea Lupu, Sai-Ching Yeung, George A. Calin
Abstract
BACKGROUND. SARS-CoV-2 infection in Africa has been characterized by less severe disease than elsewhere but the profile of SARS-CoV-2 specific adaptive immunity in this largely asymptomatic spread has not been studied. METHODS. We collected blood and nasopharyngeal samples from rural Kenyans (n=80) without respiratory symptoms since 2019, had no contact with COVID-19 cases or received COVID-19 vaccines and were negative for current SARS-CoV-2 infection. We analyzed spike-specific antibodies and T cells specific for SARS-CoV-2 structural (membrane, nucleocapsid and spike) and accessory (ORF3a, ORF7, ORF8) proteins. Pre-pandemic samples collected in urban Nairobi, Kenya (n=13) between 2015-2016 and samples of mild-moderately symptomatic COVID-19 convalescents (n=36) living in the urban environment of Singapore were also studied. RESULTS. Among asymptomatic Kenyans, we detected anti-spike antibodies in 41.0% and T cell responses against ≥2 SARS-CoV-2 proteins in 82.5%. The pre-pandemic samples from Nairobi had low-level, monospecific responses. Furthermore, distinct from cellular immunity in European and Asian COVID-19 convalescents, strong T cell immunogenicity was observed against viral accessory proteins (ORF3a, ORF8) and not structural proteins, as well as a higher IL-10/IFN-γ ratio cytokine profile. CONCLUSIONS. The high incidence of T cell responses against different SARS-CoV-2 proteins in largely seronegative participants suggests that serosurveys underestimate SARS-CoV-2 prevalence in settings where asymptomatic infections prevail. Similar observations have been made with other coronavirus infections such as MERS and SARS-CoV-1. The functional and antigen-specific profile of SARS-CoV-2 specific T cells in these African individuals suggests that genetic or environmental factors play a role in the development of protective antiviral immunity. FUNDINGS. U.S. Centers for Disease Control and Prevention, Division of Global Health Protection; the Singapore Ministry of Health’s National Medical Research Council.
Authors
Taraz Samandari, Joshua Ongalo, Kimberly McCarthy, Richard K. Biegon, Philister Madiega, Anne Mithika, Joseph Orinda, Grace M. Mboya, Patrick Mwaura, Omu Anzala, Clayton Onyango, Fredrick O. Oluoch, Eric M. Osoro, Charles-Antoine Dutertre, Nicole Tan, Shou Kit Hang, Smrithi Hariharaputran, David C. Lye, Amy Herman-Roloff, Nina Le Bert, Antonio Bertoletti
Abstract
The ADP ribosyl transferases (PARPs 1–17) regulate diverse cellular processes, including DNA damage repair. PARPs are classified based on their ability to catalyze poly-ADP-ribosylation (PARylation) or mono-ADP-ribosylation (MARylation). While PARP9 mRNA expression is significantly increased in progressive human tuberculosis (TB), its participation in host immunity to TB is unknown. Here, we show that PARP9 mRNA encoding the MARylating PARP9 enzyme is upregulated during TB in humans and mice and provide evidence of a critical modulatory role for PARP9 in DNA damage, cGAS and type I IFN production during TB. Thus, Parp9-deficient mice are susceptible to Mtb infection and exhibit increased TB disease, cGAS expression, cGAMP and type I IFN production along with upregulation of complement and coagulation pathways. Enhanced Mtb susceptibility is type I IFN-dependent, as blockade of IFNAR signaling reversed the enhanced susceptibility of Parp9-/- mice. Thus, in sharp contrast with PARP9 enhancement of type I IFN production in viral infections, this member of the MAR family plays a protective role by limiting type I IFN responses during TB.
Authors
Shyamala Thirunavukkarasu, Mushtaq Ahmed, Bruce A. Rosa, Mark Boothby, Sung Hoon Cho, Javier Rangel-Moreno, Stanley K. Mbandi, Valérie Schreiber, Ananya Gupta, Joaquin Zúñiga, Makedonka Mitreva, Deepak Kaushal, Thomas J. Scriba, Shabaana A. Khader
Abstract
Heterogeneity in human immune responses is difficult to model in standard laboratory mice. To understand how host variation affects BCG-induced immunity against Mycobacterium tuberculosis, we studied 24 unique Collaborative Cross (CC) mouse strains, which differ primarily in the genes and alleles they inherit from founder strains. The CC strains were vaccinated with or without BCG, and then challenged with aerosolized M. tuberculosis. As BCG protects only half of the CC strains tested, we conclude that host genetics has a major influence on BCG-induced immunity against M. tuberculosis infection, making it an important barrier to vaccine-mediated protection. Importantly, BCG efficacy is dissociable from inherent susceptibility to TB. T cell immunity was extensively characterized to identify components associated with protection that were stimulated by BCG and recalled after Mtb infection. Although considerable diversity is observed, BCG has little impact on the composition of T cells in the lung after infection. Instead, variability is largely shaped by host genetics. BCG-elicited protection against TB correlated with changes in immune function. Thus, CC mice can be used to define correlates of protection and to identify vaccine strategies that protect a larger fraction of genetically diverse individuals instead of optimizing protection for a single genotype.
Authors
Rocky Lai, Diana N. Gong, Travis Williams, Abiola F. Ogunsola, Kelly Cavallo, Cecilia S. Lindestam Arlehamn, Sarah Acolatse, Gillian Beamer, Martin T. Ferris, Christopher M. Sassetti, Douglas A. Lauffenburger, Samuel M. Behar
Abstract
BACKGROUND. Despite guidelines promoting the prevention and aggressive treatment of ventilator-associated pneumonia (VAP), the importance of VAP as a driver of outcomes in mechanically ventilated patients, including patients with severe COVID-19, remains unclear. We aimed to determine the contribution of unsuccessful treatment of VAP to mortality in patients with severe pneumonia. METHODS. We performed a single-center prospective cohort study of 585 mechanically ventilated patients with severe pneumonia and respiratory failure, 190 of whom had COVID-19, who underwent at least one bronchoalveolar lavage. A panel of ICU physicians adjudicated pneumonia episodes and endpoints based on clinical and microbiologic data. Given the relatively long ICU length of stay among patients with COVID-19, we developed a machine learning approach called CarpeDiem, which groups similar ICU patient-days into clinical states based on electronic health record data. RESULTS.CarpeDiem revealed that the long ICU length of stay among patients with COVID-19 is attributable to long stays in clinical states characterized primarily by respiratory failure. While VAP was not associated with mortality overall, mortality was higher in patients with one episode of unsuccessfully treated VAP compared with successfully treated VAP (76.4% versus 17.6%, P < 0.001). In all patients, including those with COVID-19, CarpeDiem demonstrated that unresolving VAP was associated with transitions to clinical states associated with higher mortality. CONCLUSIONS. Unsuccessful treatment of VAP is associated with greater mortality. The relatively long length of stay among patients with COVID-19 is primarily due to prolonged respiratory failure, placing them at higher risk of VAP. FUNDING. U19AI135964
Authors
Catherine A. Gao, Nikolay S. Markov, Thomas Stoeger, Anna E. Pawlowski, Mengjia Kang, Prasanth Nannapaneni, Rogan A. Grant, Chiagozie Pickens, James M. Walter, Jacqueline M. Kruser, Luke V. Rasmussen, Daniel Schneider, Justin Starren, Helen K. Donnelly, Alvaro Donayre, Yuan Luo, G.R. Scott Budinger, Richard G. Wunderink, Alexander V. Misharin, Benjamin D. Singer
Abstract
Neonatal herpes simplex virus (HSV) infection is a devastating disease with substantial morbidity and mortality. The genetic basis of susceptibility to HSV in neonates remains undefined. We investigated a male infant with neonatal skin/eye/mouth (SEM) HSV1 disease who had complete recovery after acyclovir but developed HSV1 encephalitis at 1 year of age. Immune work up showed an anergic peripheral blood monocyte cytokine (PBMC) response to TLR3 stimulation but no other TLRs. Exome sequencing identified rare missense variants in IRF7 and UNC93B1. PBMC single cell RNA sequencing done during childhood revealed decreased expression of several innate immune genes and a repressed TLR3 pathway signature at baseline in several immune cell populations, including CD14 monocytes. Functional studies in fibroblasts and THP-1 showed that both variants individually suppressed TLR3-driven IRF3 promoter activity and type I interferon response in vitro. Furthermore, fibroblasts expressing the IRF7 and UNC93B1 variants had higher intracellular viral titers with blunting of the type I interferon response upon HSV1 challenge. This study reports an infant with recurrent HSV1 disease complicated by encephalitis associated with deleterious variants in IRF7 and UNC93B1 genes. Our results suggest that TLR3 pathway mutations may predispose neonates to recurrent severe HSV.
Authors
Megan H. Tucker, Wei Yu, Heather L. Menden, Sheng Xia, Carl F. Schreck, Margaret I. Gibson, Daniel A. Louiselle, Tomi Pastinen, Nikita Raje, Venkatesh Sampath
Abstract
Ferritin, a key regulator of iron homeostasis in macrophages, has been reported to confer host defenses against Mycobacterium tuberculosis (Mtb) infection. Nuclear receptor coactivator 4 (NCOA4) was recently identified as a cargo receptor in ferritin degradation. Here, we show that Mtb infection enhanced NCOA4-mediated ferritin degradation in macrophages, which in turn increased the bioavailability of iron to intracellular Mtb and therefore promoted bacterial growth. Of clinical relevance, the upregulation of FTH1 in macrophages was associated with tuberculosis (TB) disease progression in humans. Mechanistically, Mtb infection enhanced NCOA4-mediated ferritin degradation through p38/AKT1- and TRIM21-mediated proteasomal degradation of HERC2, an E3 ligase of NCOA4. Finally, we confirmed that NCOA4 deficiency in myeloid cells expedites the clearance of Mtb infection in a murine model. Together, our findings revealed a strategy by which Mtb hijacks host ferritin metabolism for its own intracellular survival. Therefore, this represents a potential target for host-directed therapy against tuberculosis.
Authors
Youchao Dai, Chuanzhi Zhu, Wei Xiao, Kaisong Huang, Xin Wang, Chenyan Shi, Dachuan Lin, Huihua Zhang, Xiaoqian Liu, Bin Peng, Yi Gao, Cui Hua Liu, Baoxue Ge, Stefan H.E. Kaufmann, Carl G. Feng, Xinchun Chen, Yi Cai
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Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)