The mechanisms underlying susceptibility to recurrent herpes simplex virus type 2 (HSV-2) meningitis remain incompletely understood. In a patient experiencing multiple episodes of HSV-2 meningitis, we identified a monoallelic variant in the IKBKE gene, which encodes the IKKε kinase involved in induction of antiviral IFN genes. Patient cells displayed impaired induction of IFN-β1 (IFNB1) expression upon infection with HSV-2 or stimulation with double-stranded DNA (dsDNA) and failed to induce phosphorylation of STING, an activation marker of the DNA-sensing cyclic GMP-AMP synthase/stimulator of IFN genes (cGAS/STING) pathway. The patient allele encoded a truncated IKKε protein with loss of kinase activity and also capable of exerting dominant-negative activity. In stem cell–derived microglia, HSV-2–induced expression of IFNB1 was dependent on cGAS, TANK binding kinase 1 (TBK1), and IKBKE, but not TLR3, and supernatants from HSV-2–treated microglia exerted IKBKE-dependent type I IFN–mediated antiviral activity upon neurons. Reintroducing wild-type IKBKE into patient cells rescued IFNB1 induction following treatment with HSV-2 or dsDNA and restored antiviral activity. Collectively, we identify IKKε to be important for protection against HSV-2 meningitis and suggest a nonredundant role for the cGAS/STING pathway in human antiviral immunity.
Azadeh Reyahi, Marie Studahl, Morten K. Skouboe, Stefanie Fruhwürth, Ryo Narita, Fanghui Ren, Moa Bjerhem Viklund, Marie B. Iversen, Mette Christiansen, Alexandra Svensson, Trine H. Mogensen, Kristina Eriksson, Søren R. Paludan
Malaria can quickly progress from an uncomplicated infection into a life-threatening severe disease. However, the unspecificity of early symptoms often makes difficult to identify patients at high-risk of developing severe disease. Additionally, one of the most feared malaria complications -cerebral malaria- is challenging to diagnose, often resulting in treatment delays that can lead to adverse outcomes.To identify candidate biomarkers for the prognosis and/or diagnosis of severe and cerebral malaria, we have analyzed the transcriptomic response of human brain microvascular endothelial cells to erythrocytes infected with Plasmodium falciparum. Candidates were validated in plasma samples from a cohort of malaria pediatric patients from Mozambique (n = 264), resulting in the identification of several markers with capacity to distinguish uncomplicated from severe malaria, the most potent being the metallopeptidase ADAMTS18 (AUC = 0.77, P < 0.0001). Two other biomarkers, Angiopoietin-like-4 and Inhibin-βE were able to differentiate children with cerebral malaria within the severe malaria group, showing increased sensitivity after combination in a biomarker signature (AUC = 0.76, P < 0.0001).The validation of the predicted candidate biomarkers in plasma of children with severe and cerebral malaria underscores the power of this transcriptomic approach and indicates that a specific endothelial response to P. falciparum-infected erythrocytes is linked to the pathophysiology of severe malaria.
Claudia Gomes, Rosauro Varo, Miquel Duran-Frigola, Antonio Sitoe, Rubão Bila, Sonia Machevo, Alfredo Mayor, Quique Bassat, Ana Rodriguez
A better understanding of the epitopes most relevant for antibody-mediated protection against tuberculosis (TB) remains a major knowledge gap. We have shown that human polyclonal IgG to the Mycobacterium tuberculosis (Mtb) surface glycan arabinomannan (AM) and related lipoarabinomannan (LAM) is protective against TB. To investigate the impact of AM epitope recognition and Fc-gamma receptor (FcgR)-binding on antibody functions against Mtb, we isolated a high-affinity human monoclonal antibody (mAb; P1AM25) to AM and show its binding to oligosaccharide (OS) motifs we previously found to be associated with in vitro functions of human polyclonal anti-AM IgG. Human IgG1 P1AM25, but not two other high-affinity human IgG1 anti-AM mAbs reactive with different AM OS motifs, enhanced Mtb phagocytosis by macrophages and reduced intracellular growth in an FcgR-dependent manner. P1AM25 in murine IgG2a, but neither murine IgG1 nor a non-FcgR-binding IgG, given intraperitoneally prior to and after aerosolized Mtb infection was protective in C57BL/6 mice. Moreover, we demonstrate the protective efficacy of human IgG1 P1AM25 in passive transfer with Mtb-infected FcgR-humanized mice. These data enhance our knowledge of the important interplay between both antibody epitope specificity and Fc effector functions in the defense against Mtb and could inform development strategies of vaccines against TB.
Yanyan Liu, Tingting Chen, Yongqi Zhu, Aisha Furey, Todd L. Lowary, John Chan, Stylianos Bournazos, Jeffrey V. Ravetch, Jacqueline M. Achkar
Host cytosolic sensing of Mycobacterium tuberculosis (M.tb) RNA by the RIG I-like receptor (RLR) family perturbs innate immune control within macrophages; however, a distinct role of MDA5, a member of the RLR family, in M.tb pathogenesis has yet to be fully elucidated. To further define the role of MDA5 in M.tb pathogenesis, we evaluated M.tb intracellular growth and innate immune responses in wild-type and Mda5-/- macrophages. Transfection of M.tb RNA strongly induced pro-inflammatory cytokine production in WT macrophages, which was abrogated in Mda5-/- macrophages. M.tb infection in macrophages induced MDA5 protein expression, accompanied by an increase in MDA5 activation as assessed by multimer formation. IFNγ-primed Mda5-/- macrophages effectively contained intracellular M.tb proliferation to a significantly greater degree than WT macrophages. Further comparisons of WT versus Mda5-/- macrophages revealed that during M.tb infection MDA5 contributes to IL-1β production and inflammasome activation, and that loss of MDA5 leads to a significant increase in autophagy. In the mouse TB model, loss of MDA5 conferred host survival benefits with a concomitant reduction in M.tb bacillary burden. These data reveal that loss of MDA5 is host-protective during M.tb infection in vitro and in vivo, suggesting M.tb exploits MDA5 to subvert immune containment.
C. Korin Bullen, Alok K. Singh, Stefanie Krug, Shichun Lun, Preeti Thakur, Geetha Srikrishna, William R. Bishai
Given the resurgence of pertussis, several countries have introduced maternal tetanus, diphtheria, and acellular pertussis (aP) vaccination during pregnancy to protect young infants against severe pertussis. Although protective against the disease, the effect of maternal aP vaccination on bacterial colonization of the offspring is unknown. Here, we used a mouse model to demonstrate that maternal aP immunization, either before or during pregnancy, protects pups from lung colonization by Bordetella pertussis. However, it substantially prolongs nasal carriage by inhibiting the recruitment of IL-17-producing resident memory T cells and ensuing neutrophil influx in the nasal tissue upon B. pertussis infection, especially of those with pro-inflammatory and cytotoxic properties. Prolonged nasal carriage after aP vaccination is due to IL-4 signaling, as it is abolished in IL-4Ra-/- mice. The effect of maternal aP vaccination can be transferred transplacentally to the offspring or by breastfeeding and is long-lasting, as it persists into adulthood. Maternal aP vaccination may thus potentially augment the B. pertussis reservoir.
Violaine Dubois, Jonathan Chatagnon, Manon Depessemier, Camille Locht
Resolution of T cell activation and inflammation is a key determinant of the lack of SIV disease progression in African green monkeys (AGMs). Although frequently considered together, T cell activation occurs in response to viral stimulation of acquired immunity, while inflammation reflects innate immune responses to mucosal injury. We dissociated T cell activation from inflammation through regulatory T cell (Treg) depletion with Ontak (interleukin-2 coupled with diphtheria toxin) during early SIV infection of AGMs. This intervention abolished control of T cell immune activation beyond the transition from acute to chronic infection. Ontak had no effect on gut barrier integrity, microbial translocation, inflammation, and hypercoagulation, despite increasing T cell activation. Ontak administration increased macrophage counts yet decreased their activation. Persistent T cell activation influenced SIV pathogenesis, shifting the ramp-up in viral replication to earlier time points, prolonging the high levels of replication, and delaying CD4+ T cell restoration yet without any clinical or biological sign of disease progression in Treg-depleted AGMs. Thus, by inducing T cell activation without damaging mucosal barrier integrity, we showed that systemic T cell activation per se is not sufficient to drive disease progression, which suggests that control of systemic inflammation (likely through maintenance of gut integrity) is the key determinant of lack of disease progression in natural hosts of SIVs.
Cristian Apetrei, Thaidra Gaufin, Egidio Brocca-Cofano, Ranjit Sivanandham, Paola Sette, Tianyu He, Sindhuja Sivanandham, Natalie Martinez Sosa, Kathryn J. Martin, Kevin D. Raehtz, Adam J. Kleinman, Audrey Valentine, Noah Krampe, Rajeev Gautam, Andrew A. Lackner, Alan L. Landay, Ruy M. Ribeiro, Ivona Pandrea
Human cytomegalovirus (HCMV) is the most common vertically transmitted infection worldwide, yet there are no vaccines or therapeutics to prevent congenital HCMV (cCMV) infection. Emerging evidence indicates that antibody Fc effector functions may be a previously underappreciated component of maternal immunity against HCMV. We recently reported that antibody-dependent cellular phagocytosis (ADCP) and IgG activation of FcγRI/FcγRII were associated with protection against cCMV transmission, leading us to hypothesize that additional Fc-mediated antibody functions may be important. In this same cohort of HCMV-transmitting (n = 41) and nontransmitting (n = 40) mother-infant dyads, we report that higher maternal sera antibody–dependent cellular cytotoxicity (ADCC) activation is also associated with lower risk of cCMV transmission. We investigated the relationship between ADCC and IgG responses against 9 viral antigens and found that ADCC activation correlated most strongly with sera IgG binding to the HCMV immunoevasin protein UL16. Moreover, we determined that higher UL16-specific IgG binding and FcγRIII/CD16 engagement were associated with the greatest risk reduction in cCMV transmission. Our findings indicate that ADCC-activating antibodies against targets such as UL16 may represent an important protective maternal immune response against cCMV infection that can guide future HCMV correlates studies and vaccine or antibody-based therapeutic development.
Eleanor C. Semmes, Itzayana G. Miller, Nicole Rodgers, Caroline T. Phan, Jillian H. Hurst, Kyle M. Walsh, Richard J. Stanton, Justin Pollara, Sallie R. Permar
The inactivated vaccine CoronaVac is one of the most widely used COVID-19 vaccines globally. However, the longitudinal evolution of the immune response induced by CoronaVac remains elusive compared to other vaccine platforms. Here, we recruited 88 healthy individuals that received 3 doses of CoronaVac vaccine. We longitudinally evaluated their polyclonal and antigen-specific CD4+ T cells and neutralizing antibody response after receiving each dose of vaccine for over 300 days. Both the 2nd and 3rd dose of vaccination induced robust spike-specific neutralizing antibodies, with a 3rd vaccine further increased the overall magnitude of antibody response, and neutralization against Omicron sub-lineages B.1.1.529, BA.2, BA.4/BA.5 and BA.2.75.2. Spike-specific CD4+ T cell and circulating T follicular helper (cTFH) cells were markedly increased by the 2nd and 3rd dose of CoronaVac vaccine, accompanied with altered composition of functional cTFH cell subsets with distinct effector and memory potential. Additionally, cTFH cells are positively correlated with neutralizing antibody titers. Our results suggest that CoronaVac vaccine-induced spike-specific T cells are capable of supporting humoral immunity for long-term immune protection.
Pengcheng Zhou, Cheng Cao, Tuo Ji, Ting Zheng, Yaping Dai, Min Liu, Junfeng Jiang, Daoqi Sun, Zhonghu Bai, Xiaojie Lu, Fang Gong
Influenza A virus (IAV) infection is commonly complicated by secondary bacterial infections, leading to increased morbidity and mortality. Our recent work demonstrates that IAV disrupts airway homeostasis, leading to airway pathophysiology resembling cystic fibrosis disease through diminished cystic fibrosis transmembrane conductance regulator (CFTR) function. Here, we use human airway organotypic cultures to investigate how IAV alters the airway microenvironment to increase susceptibility to secondary infection with Streptococcus pneumoniae (Spn). We observed that IAV-induced CFTR dysfunction and airway surface liquid acidification is central to increasing susceptibility to Spn. Additionally, we observed that IAV induced profound transcriptional changes in the airway epithelium and proteomic changes in the airway surface liquid in both CFTR dependent and independent manners. These changes correspond to multiple diminished host defense pathways and altered airway epithelial function. Collectively, these findings highlight both the importance of CFTR function during infectious challenge and demonstrate a central role for the lung epithelium in secondary bacterial infections following IAV.
Erin Y. Earnhardt, Jennifer L. Tipper, Adonis D'Mello, Ming-Yuan Jian, Elijah S. Conway, James A. Mobley, Carlos J. Orihuela, Hervé Tettelin, Kevin S. Harrod
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
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