A glucan-particle based tularemia subunit vaccine induces T-cell immunity and affords partial protection in an inhalation rat infection model.

Tularemia is a zoonotic disease caused by the facultative intracellular gram-negative bacterium Francisella tularensis. F. tularensis has a very low infection dose by the aerosol route which can result in an acute, and potentially lethal, infection in humans. Consequently, it is classified as a Category A bioterrorism agent by the US Centers for Disease Control (CDC) and is a pathogen of concern for the International Biodefence community. There are currently no licenced tularemia vaccines. In this study we report on the continued assessment of a tularemia subunit vaccine utilising ß-glucan particles (GPs) as a vaccine delivery platform for immunogenic F. tularensis antigens. Using a Fischer 344 rat infection model, we demonstrate that a GP based vaccine comprising the F. tularensis lipopolysaccharide antigen together with the protein antigen FTT0814 provided partial protection of F344 rats against an aerosol challenge with a high virulence strain of F. tularensis, SCHU S4. Inclusion of imiquimod as an adjuvant failed to enhance protective efficacy. Moreover, the level of protection afforded was dependant on the challenge dose. Immunological characterisation of this vaccine demonstrated that it induced strong antibody immunoglobulin responses to both polysaccharide and protein antigens. Furthermore, we demonstrate that the FTT0814 component of the GP vaccine primed CD4+ and CD8+ T-cells from immunised F344 rats to express interferon-γ, and CD4+ cells to express interleukin-17, in an antigen specific manner. These data demonstrate the development potential of this tularemia subunit vaccine and builds on a body of work highlighting GPs as a promising vaccine platform for difficult to treat pathogens including those of concern to the bio-defence community.

IL-12p40 is essential but not sufficient for Francisella tularensis LVS clearance in chronically infected mice.

IL-12p40 plays an important role in F. tularensis Live Vaccine Strain (LVS) clearance that is independent of its functions as a part of the heterodimeric cytokines IL-12p70 or IL-23. In contrast to WT, p35, or p19 knockout (KO) mice, p40 KO mice infected with LVS develop a chronic infection that does not resolve. Here, we further evaluated the role of IL-12p40 in F. tularensis clearance. Despite reduced IFN-γ production, primed splenocytes from p40 KO and p35 KO mice appeared functionally similar to those from WT mice during in vitro co-culture assays of intramacrophage bacterial growth control. Gene expression analysis revealed a subset of genes that were upregulated in re-stimulated WT and p35 KO splenocytes, but not p40 KO splenocytes, and thus are candidates for involvement in F. tularensis clearance. To directly evaluate a potential mechanism for p40 in F. tularensis clearance, we reconstituted protein levels in LVS-infected p40 KO mice using either intermittent injections of p40 homodimer (p80) or treatment with a p40-producing lentivirus construct. Although both delivery strategies yielded readily detectable levels of p40 in sera and spleens, neither treatment had a measurable impact on LVS clearance by p40 KO mice. Taken together, these studies demonstrate that clearance of F. tularensis infection depends on p40, but p40 monomers and/or dimers alone are not sufficient.

Circulating T Cells Are Not Sufficient for Protective Immunity against Virulent Francisella tularensis.

Pulmonary infections elicit a combination of tissue-resident and circulating T cell responses. Understanding the contribution of these anatomically distinct cellular pools in protective immune responses is critical for vaccine development. Francisella tularensis is a highly virulent bacterium capable of causing lethal systemic disease following pulmonary infection for which there is no currently licensed vaccine. Although T cells are required for survival of F. tularensis infection, the relative contribution of tissue-resident and circulating T cells is not completely understood, hampering design of effective, long-lasting vaccines directed against this bacterium. We have previously shown that resident T cells were not sufficient to protect against F. tularensis, suggesting circulating cells may serve a critical role in host defense. To elucidate the role of circulating T cells, we used a model of vaccination and challenge of parabiotic mice. Intranasally infected naive mice conjoined to immune animals had increased numbers of circulating memory T cells and similar splenic bacterial burdens as vaccinated-vaccinated pairs. However, bacterial loads in the lungs of naive parabionts were significantly greater than those observed in vaccinated-vaccinated pairs, but despite early control of F. tularensis replication, all naive-vaccinated pairs succumbed to infection. Together, these data define the specific roles of circulating and resident T cells in defense against infection that is initiated in the pulmonary compartment but ultimately causes disseminated disease. These data also provide evidence for employing vaccination strategies that elicit both pools of T cells for immunity against F. tularensis and may be a common theme for other disseminating bacterial infections.

Critical role of IL-25-ILC2-IL-5 axis in the production of anti-Francisella LPS IgM by B1 B cells.

B1 cells, a subset of B lymphocytes whose developmental origin, phenotype, and function differ from that of conventional B2 cells, are the main source of "natural" IgM but can also respond to infection by rapidly producing pathogen-specific IgM directed against T-independent antigens. Francisella tularensis (Ft) is a Gram-negative bacterium that causes tularemia. Infection with Ft Live Vaccine Strain activates B1 cells for production of IgM directed against the bacterial LPS in a process incompletely understood. Here we show that immunization with purified Ft LPS elicits production of LPS-specific IgM and IgG3 by B1 cells independently of TLR2 or MyD88. Immunization, but not infection, generated peritoneum-resident memory B1 cells that differentiated into LPS-specific antibody secreting cells (ASC) upon secondary challenge. IL-5 was rapidly induced by immunization with Ft LPS and was required for production of LPS-specific IgM. Antibody-mediated depletion of ILC2 indicated that these cells were the source of IL-5 and were required for IgM production. IL-25, an alarmin that strongly activates ILC2, was rapidly secreted in response to immunization or infection and its administration to mice significantly increased IgM production and B1 cell differentiation to ASC. Conversely, mice lacking IL-17RB, the IL-25 receptor, showed impaired IL-5 induction, IgM production, and B1 ASC differentiation in response to immunization. Administration of IL-5 to Il17rb-/- mice rescued these B1 cells-mediated responses. Il17rb-/- mice were more susceptible to infection with Ft LVS and failed to develop immunity upon secondary challenge suggesting that LPS-specific IgM is one of the protective adaptive immune mechanisms against tularemia. Our results indicated that immunization with Ft LPS triggers production of IL-25 that, through stimulation of IL-5 release by ILC2, promotes B1 cells activation and differentiation into IgM secreting cells. By revealing the existence of an IL-25-ILC2-IL-5 axis our results suggest novel strategies to improve vaccination against T-independent bacterial antigens.

Francisella tularensis Infection of Mice as a Model of Sepsis.

Sepsis results from the dysregulated immune response to infection. While the stimulator and progression of the septic response is poorly understood, the systemic production of a storm of cytokines is common in all etiologies of sepsis. While the complexity of this uncontrolled cascade is difficult to replicate using single molecule agonist, for example, lipopolysaccharide (LPS), several whole organism models can stimulate this cytokine storm. Herein, we detail protocols developed to trigger and analyze the systemic septic response in mouse models using the bacterium Francisella tularensis.

A study of innate immune kinetics reveals a role for a chloride transporter in a virulent Francisella tularensis type B strain.

Tularemia is a zoonotic disease of global proportions. Francisella tularensis subspecies tularensis (type A) and holarctica (type B) cause disease in healthy humans, with type A infections resulting in higher mortality. Repeated passage of a type B strain in the mid-20th century generated the Live Vaccine Strain (LVS). LVS remains unlicensed, does not protect against high inhalational doses of type A, and its exact mechanisms of attenuation are poorly understood. Recent data suggest that live attenuated vaccines derived from type B may cross-protect against type A. However, there is a dearth of knowledge regarding virulent type B pathogenesis and its capacity to stimulate the host's innate immune response. We therefore sought to increase our understanding of virulent type B in vitro characteristics using strain OR96-0246 as a model. Adding to our knowledge of innate immune kinetics in macrophages following infection with virulent type B, we observed robust replication of strain OR96-0246 in murine and human macrophages, reduced expression of pro-inflammatory cytokine genes from "wild type" type B-infected macrophages compared to LVS, and delayed macrophage cell death suggesting that virulent type B may suppress macrophage activation. One disruption in LVS is in the gene encoding the chloride transporter ClcA. We investigated the role of ClcA in macrophage infection and observed a replication delay in a clcA mutant. Here, we propose its role in acid tolerance. A greater understanding of LVS attenuation may reveal new mechanisms of pathogenesis and inform strategies toward the development of an improved vaccine against tularemia.

Tick-human interactions: from allergic klendusity to the α-Gal syndrome.

Ticks and the pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. The ability of some animal species to acquire resistance to blood-feeding by ticks after a single or repeated infestation is known as acquired tick resistance (ATR). This resistance has been associated to tick-specific IgE response, the generation of skin-resident memory CD4+ T cells, basophil recruitment, histamine release, and epidermal hyperplasia. ATR has also been associated with protection to tick-borne tularemia through allergic klendusity, a disease-escaping ability produced by the development of hypersensitivity to an allergen. In addition to pathogen transmission, tick infestation in humans is associated with the α-Gal syndrome (AGS), a type of allergy characterized by an IgE response against the carbohydrate Galα1-3Gal (α-Gal). This glycan is present in tick salivary proteins and on the surface of tick-borne pathogens such as Borrelia burgdorferi and Anaplasma phagocytophilum, the causative agents of Lyme disease and granulocytic anaplasmosis. Most α-Gal-sensitized individuals develop IgE specific against this glycan, but only a small fraction develop the AGS. This review summarizes our current understanding of ATR and its impact on the continuum α-Gal sensitization, allergy, and the AGS. We propose that the α-Gal-specific IgE response in humans is an evolutionary adaptation associated with ATR and allergic klendusity with the trade-off of developing AGS.

Aim2 and Nlrp3 Are Dispensable for Vaccine-Induced Immunity against Francisella tularensis Live Vaccine Strain.

Francisella tularensis is a facultative, intracellular, Gram-negative bacterium that causes a fatal disease known as tularemia. Due to its extremely high virulence, ease of spread by aerosolization, and potential to be used as a bioterror agent, F. tularensis is classified by the CDC as a tier 1 category A select agent. Previous studies have demonstrated the roles of the inflammasome sensors absent in melanoma 2 (AIM2) and NLRP3 in the generation of innate immune responses to F. tularensis infection. However, contributions of both the AIM2 and NLRP3 to the development of vaccine-induced adaptive immune responses against F. tularensis are not known. This study determined the contributions of Aim2 and Nlrp3 inflammasome sensors to vaccine-induced immune responses in a mouse model of respiratory tularemia. We developed a model to vaccinate Aim2- and Nlrp3-deficient (Aim2-/- and Nlrp3-/-) mice using the emrA1 mutant of the F. tularensis live vaccine strain (LVS). The results demonstrate that the innate immune responses in Aim2-/- and Nlrp3-/- mice vaccinated with the emrA1 mutant differ from those of their wild-type counterparts. However, despite these differences in the innate immune responses, both Aim2-/- and Nlrp3-/- mice are fully protected against an intranasal lethal challenge dose of F. tularensis LVS. Moreover, the lack of both Aim2 and Nlrp3 inflammasome sensors does not affect the production of vaccination-induced antibody and cell-mediated responses. Overall, this study reports a novel finding that both Aim2 and Nlrp3 are dispensable for vaccination-induced immunity against respiratory tularemia caused by F. tularensis.

Deficiency in CCR2 increases susceptibility of mice to infection with an intracellular pathogen, Francisella tularensis LVS, but does not impair development of protective immunity.

CCR2 is the major chemokine receptor that regulates appropriate trafficking of inflammatory monocytes, but the role of this chemokine receptor and its ligands during primary and secondary infection with intracellular infections remains incompletely understood. Here we used murine infection with the Live Vaccine Strain (LVS) of Francisella tularensis to evaluate the role of CCR2 during primary and secondary parenteral responses to this prototype intracellular bacterium. We find that mice deficient in CCR2 are highly compromised in their ability to survive intradermal infection with LVS, indicating the importance of this receptor during primary parenteral responses. Interestingly, this defect could not be readily attributed to the activities of the known murine CCR2 ligands MCP-1/CCL2, MCP-3/CCL7, or MCP-5/CCL12. Nonetheless, CCR2 knockout mice vaccinated by infection with low doses of LVS generated optimal T cell responses that controlled the intramacrophage replication of Francisella, and LVS-immune CCR2 knockout mice survived maximal lethal Francisella challenge. Thus, fully protective adaptive immune memory responses to this intracellular bacterium can be readily generated in the absence of CCR2.

Early infection-induced natural antibody response.

There remains to this day a great gap in understanding as to the role of B cells and their products-antibodies and cytokines-in mediating the protective response to Francisella tularensis, a Gram-negative coccobacillus belonging to the group of facultative intracellular bacterial pathogens. We previously have demonstrated that Francisella interacts directly with peritoneal B-1a cells. Here, we demonstrate that, as early as 12 h postinfection, germ-free mice infected with Francisella tularensis produce infection-induced antibody clones reacting with Francisella tularensis proteins having orthologs or analogs in eukaryotic cells. Production of some individual clones was limited in time and was influenced by virulence of the Francisella strain used. The phylogenetically stabilized defense mechanism can utilize these early infection-induced antibodies both to recognize components of the invading pathogens and to eliminate molecular residues of infection-damaged self cells.

Macrophages Demonstrate Guanylate-Binding Protein-Dependent and Bacterial Strain-Dependent Responses to Francisella tularensis.

Francisella tularensis is a facultative intracellular bacterium and the etiological agent of tularemia, a zoonotic disease. Infection of monocytic cells by F. tularensis can be controlled after activation with IFN-γ; however, the molecular mechanisms whereby the control is executed are incompletely understood. Recently, a key role has been attributed to the Guanylate-binding proteins (GBPs), interferon-inducible proteins involved in the cell-specific immunity against various intracellular pathogens. Here, we assessed the responses of bone marrow-derived murine macrophages (BMDM) and GBP-deficient BMDM to F. tularensis strains of variable virulence; the highly virulent SCHU S4 strain, the human live vaccine strain (LVS), or the widely used surrogate for F. tularensis, the low virulent F. novicida. Each of the strains multiplied rapidly in BMDM, but after addition of IFN-γ, significant GBP-dependent control of infection was observed for the LVS and F. novicida strains, whereas there was no control of the SCHU S4 infection. However, no differences in GBP transcription or translation were observed in the infected cell cultures. During co-infection with F. novicida and SCHU S4, significant control of both strains was observed. Patterns of 18 cytokines were very distinct between infected cell cultures and high levels were observed for almost all cytokines in F. novicida-infected cultures and very low levels in SCHU S4-infected cultures, whereas levels in co-infected cultures for a majority of cytokines showed intermediate levels, or levels similar to those of F. novicida-infected cultures. We conclude that the control of BMDM infection with F. tularensis LVS or F. novicida is GBP-dependent, whereas SCHU S4 was only controlled during co-infection. Since expression of GBP was similar regardless of infecting agent, the findings imply that SCHU S4 has an inherent ability to evade the GBP-dependent anti-bacterial mechanisms.

Immune lymphocytes halt replication of Francisella tularensis LVS within the cytoplasm of infected macrophages.

Francisella tularensis is a highly infectious intracellular bacterium that causes tularemia by invading and replicating in mammalian myeloid cells. Francisella primarily invades host macrophages, where it escapes phagosomes within a few hours and replicates in the cytoplasm. Less is known about how Francisella traffics within macrophages or exits into the extracellular environment for further infection. Immune T lymphocytes control the replication of Francisella within macrophages in vitro by a variety of mechanisms, but nothing is known about intracellular bacterial trafficking in the face of such immune pressure. Here we used a murine model of infection with a Francisella attenuated live vaccine strain (LVS), which is under study as a human vaccine, to evaluate the hypothesis that immune T cells control intramacrophage bacterial growth by re-directing bacteria into toxic intracellular compartments of infected macrophages. We visualized the interactions of lymphocytes and LVS-infected macrophages using confocal microscopy and characterized LVS intramacrophage trafficking when co-cultured with immune lymphocytes. We focused on the late stages of infection after bacteria escape from phagosomes, through bacterial replication and the death of macrophages. We found that the majority of LVS remained cytosolic in the absence of immune pressure, eventually resulting in macrophage death. In contrast, co-culture of LVS-infected macrophages with LVS-immune lymphocytes halted LVS replication and inhibited the spread of LVS infection between macrophages, but bacteria did not return to vacuoles such as lysosomes or autophagosomes and macrophages did not die. Therefore, immune lymphocytes directly limit intracellular bacterial replication within the cytoplasm of infected macrophages.

OpiA, a Type Six Secretion System Substrate, Localizes to the Cell Pole and Plays a Role in Bacterial Growth and Viability in Francisella tularensis LVS.

Francisella tularensis is an intracellular pathogen and the causative agent of tularemia. The F. tularensis type six secretion system (T6SS) is required for a number of host-pathogen interactions, including phagolysosomal escape and invasion of erythrocytes. One known effector of the T6SS, OpiA, has recently been shown to be a phosphatidylinositol-3 kinase. To investigate the role of OpiA in erythrocyte invasion, we constructed an opiA-null mutant in the live vaccine strain, F. tularensis LVS. OpiA was not required for erythrocyte invasion; however, deletion of opiA affected growth of F. tularensis LVS in broth cultures in a medium-dependent manner. We also found that opiA influenced cell size, gentamicin sensitivity, bacterial viability, and the lipid content of F. tularensis A fluorescently tagged OpiA (OpiA-emerald-green fluorescent protein [EmGFP]) accumulated at the cell poles of F. tularensis, which is consistent with the location of the T6SS. However, OpiA-EmGFP also exhibited a highly dynamic localization, and this fusion protein was detected in erythrocytes and THP-1 cells in vitro, further supporting that OpiA is secreted. Similar to previous reports with F. novicida, our data demonstrated that opiA had a minimal effect on intracellular replication of F. tularensis in host immune cells in vitro However, THP-1 cells infected with the opiA mutant produced modestly (but significantly) higher levels of the proinflammatory cytokine tumor necrosis factor alpha compared to these host cells infected with wild-type bacteria. We conclude that, in addition to its role in host-pathogen interactions, our results reveal that the function of opiA is central to the biology of F. tularensis bacteria.IMPORTANCEF. tularensis is a pathogenic intracellular pathogen that is of importance for public health and strategic defense. This study characterizes the opiA gene of F. tularensis LVS, an attenuated strain that has been used as a live vaccine but that also shares significant genetic similarity to related Francisella strains that cause human disease. The data presented here provide the first evidence of a T6SS effector protein that affects the physiology of F. tularensis, namely, the growth, cell size, viability, and aminoglycoside resistance of F. tularensis LVS. This study also adds insight into our understanding of OpiA as a determinant of virulence. Finally, the fluorescence fusion constructs presented here will be useful tools for dissecting the role of OpiA in infection.

Production of Neutrophil Extracellular Traps Contributes to the Pathogenesis of Francisella tularemia.

Francisella tularensis(Ft) is a highly virulent, intracellular Gram-negative bacterial pathogen. Acute Ft infection by aerosol route causes pneumonic tularemia, characterized by nodular hemorrhagic lesions, neutrophil-predominant influx, necrotic debris, fibrin deposition, and severe alveolitis. Ft suppresses activity of neutrophils by impairing their respiratory burst and phagocytic activity. However, the fate of the massive numbers of neutrophils recruited to the infection site is unclear. Here, we show that Ft infection resulted in prominent induction of neutrophil extracellular traps (NETs) within damaged lungs of mice infected with the live attenuated vaccine strain of Ft(Ft-LVS), as well as in the lungs of domestic cats and rabbits naturally infected with Ft. Further, Ft-LVS infection increased lung myeloperoxidase (MPO) activity, which mediates histone protein degradation during NETosis and anchors chromatin scaffolds in NETs. In addition, Ft infection also induced expression of peptidylarginine deiminase 4, an enzyme that causes citrullination of histones during formation of NETs. The released NETs were found largely attached to the alveolar epithelium, and disrupted the thin alveolar epithelial barrier. Furthermore, Ft infection induced a concentration-dependent release of NETs from neutrophils in vitro. Pharmacological blocking of MPO reduced Ft-induced NETs release, whereas addition of H2O2 (a substrate of MPO) significantly augmented NETs release, thus indicating a critical role of MPO in Ft-induced NETs. Although immunofluorescence and electron microscopy revealed that NETs could efficiently trap Ft bacteria, NETs failed to exert bactericidal effects. Taken together, these findings suggest that NETs exacerbate tissue damage in pulmonary Ft infection, and that targeting NETosis may offer novel therapeutic interventions in alleviating Ft-induced tissue damage.

A serological and molecular study on Francisella tularensis in rodents from Hamadan province, Western Iran.

INTRODUCTION AND PURPOSE: Tularemia is a zoonotic disease, the most important hosts of which are rodents. Endemic regions and reservoirs of F. tularensis are not well-researched areas in Iran. The present study aimed to study F. tularensis infection in the rodent populations of western Iran. MATERIALS AND METHODS: Samples were collected in different areas of Kabudar Ahang County in Hamadan province (west of Iran) from 2014 to 2017. Tularemia serological and molecular tests were conducted using the tube agglutination test and Real-time PCR method tracking the ISFtu2 gene. Positive serum samples were evaluated for cross-reactivity with brucellosis. RESULTS: A total of 433 rodents, collected from 33 localities, were included in the study. The most abundant species belonged to the Persian jird (Meriones persicus; 75.5%), and Libyan jird (Meriones libycus; 10.1%). Among the studied samples, three (0.74 %) were seropositive and five (1.15%) were PCR positive. Seropositive samples were two M. persicus and one M. libycus, and PCR positive rodents were four M. persicus and one M. vinogradovi. Tularemia seropositive samples showed no cross-reactivity with brucellosis. CONCLUSION: Given the presence of infection in rodents with tularemia agent in the studied area, it is crucial to elucidate the risks of rodent exposure to tularemia for physicians, health personnel and the general population.

Soluble lytic transglycosylase SLT of Francisella novicida is involved in intracellular growth and immune suppression.

Francisella tularensis, a category-A bioterrorism agent causes tularemia. F. tularensis suppresses the immune response of host cells and intracellularly proliferates. However, the detailed mechanisms of immune suppression and intracellular growth are largely unknown. Here we developed a transposon mutant library to identify novel pathogenic factors of F. tularensis. Among 750 transposon mutants of F. tularensis subsp. novicida (F. novicida), 11 were isolated as less cytotoxic strains, and the genes responsible for cytotoxicity were identified. Among them, the function of slt, which encodes soluble lytic transglycosylase (SLT) was investigated in detail. An slt deletion mutant (Δslt) was less toxic to the human monocyte cell line THP-1 vs the wild-type strain. Although the wild-type strain proliferated in THP-1 cells, the number of intracellular Δslt mutant decreased in comparison. The Δslt mutant escaped from phagosomes during the early stages of infection, but the mutant was detected within the autophagosome, followed by degradation in lysosomes. Moreover, the Δslt mutant induced host cells to produce high levels of cytokines such as tumor necrosis factor-α, interleukin (IL)-6, and IL-1ß, compared with the wild-type strain. These results suggest that the SLT of F. novicida is required for immune suppression and escape from autophagy to allow its survival in host cells.

Effect of Synthetic Organoselenium Drug on the Degree of Pathological Changes in the Organs of White Mice Immunized with Tularemia and Brucellosis Vaccines.

We studied the effect of the organoselenium compound 2,6-dipyridinium-9-selenium-bicyclo[ 3,3,1]nonan dibromide (974zh) on the severity of pathological changes in the organs of experimental animals immunized with live tularemia and brucellosis vaccines. It was found that 974zh reduced reactogenicity of vaccines for experimental animals. Our findings indicate the prospects for further studies of the effects of 974zh on the functional state of experimental animals.

Fcγ receptors and toll-like receptor 9 synergize to drive immune complex-induced dendritic cell maturation.

Previous in vivo studies established that inactivated Francisella tularensis immune complexes (mAb-iFt) are a more protective vaccine against lethal tularemia than iFt alone. Subsequent in vitro studies revealed enhanced DC maturation marker expression with mAb-iFt stimulation. The goal of this study was to determine the mechanism of enhanced DC maturation. Multiparameter analysis of surface marker expression and cytokine secretion demonstrates a requirement for FcγR signaling in enhanced DC maturation. MyD88 was also found to be essential for heightened DC maturation, implicating MyD88-dependent TLRs in DC maturation. Upon further study, we discovered that TLRs 2 & 4 drive cytokine secretion, but surprisingly TLR9 is required for DC maturation marker upregulation. These studies reveal a separation of DC cytokine and maturation marker induction pathways and demonstrate that FcγR-TLR/MyD88 synergy underlies the enhanced dendritic cell maturation in response to the mAb-iFt vaccine.

T Cell Metabolism Is Dependent on Anatomical Location within the Lung.

The metabolic shift from oxidative phosphorylation to glycolysis is universally accepted as a necessary step for immune cells to mount effector functions. However, it is unknown if this paradigm holds true for T cells regardless of anatomical location. In this study, we compared metabolic responses among distinct mouse pulmonary CD4+ effector T cell (Teff) pools following intranasal vaccination with either Francisella tularensis or Bordetella pertussis Surprisingly, in contrast to circulating CD4+ Teff, upon ex vivo stimulation, resident CD4+ Teff did not shift to glycolysis. This impairment in the resident pool was modestly overcome following in vivo infection. However, consistent with an ex vivo triggered shift toward glycolysis, circulating CD4+ Teff remained superior compared with resident CD4+ Teff after in vivo infection. These data indicate differences in lung T cell metabolism is associated with anatomic location, a feature which may be exploited to enhance or dampen pulmonary T cell responses.