Farnesol remodels the peritoneal cavity immune environment influencing Candida albicans pathogenesis during intra-abdominal infection

Candida albicans is a lifelong member of the mycobiome causing mucosal candidiasis and life-threatening, systemic, and intra-abdominal disease in immunocompromised and transplant patients. Despite the clinical importance of intra-abdominal candidiasis with mortality rates between 40% and 70%, the contribution of fungal virulence factors and host immune responses to disease has not been extensively studied. Secretion of the quorum-sensing molecule, farnesol, acts as a virulence factor for C. albicans during systemic infection, while inducing local, protective innate immune responses in oral models of infection. Previously, we reported that farnesol recruits macrophages to the peritoneal cavity in mice, suggesting a role for farnesol in innate immune responses. Here, we expand on our initial findings, showing that farnesol profoundly alters the peritoneal cavity microenvironment promoting innate inflammation. Intra-peritoneal injection of farnesol stimulates rapid local death of resident peritoneal cells followed by recruitment of neutrophils and inflammatory macrophages into the peritoneal cavity and peritoneal mesothelium associated with an early increase in chemokines followed by proinflammatory cytokines. These rapid inflammatory responses to farnesol significantly increase morbidity and mortality of mice with intra-abdominal candidiasis associated with increased formation of peritoneal adhesions, despite similar rates of fungal clearance from the peritoneal cavity and retro-peritoneal organs. C. albicans ddp3Δ/ddp3Δ knockout and reconstituted strains recapitulate these findings. This indicates that farnesol may be detrimental to the host during intra-abdominal infections. Importantly, our results highlight a need to understand how C. albicans virulence factors modulate the host immune response within the peritoneum, an exceedingly common site of Candida infection.

Influence of two-dimensional expiratory airflow variations on respiratory particle propagation during pronunciation of the fricative [f]

Propagation of respiratory particles, potentially containing viable viruses, plays a significant role in the transmission of respiratory diseases (e.g., COVID-19) from infected people. Particles are produced in the upper respiratory system and exit the mouth during expiratory events such as sneezing, coughing, talking, and singing. The importance of considering speaking and singing as vectors of particle transmission has been recognized by researchers. Recently, in a companion paper, dynamics of expiratory flow during fricative utterances were explored, and significant variations of airflow jet trajectories were reported. This study focuses on respiratory particle propagation during fricative productions and the effect of airflow variations on particle transport and dispersion as a function of particle size. The commercial ANSYS-Fluent computational fluid dynamics (CFD) software was employed to quantify the fluid flow and particle dispersion from a two-dimensional mouth model of sustained fricative [f] utterance as well as a horizontal jet flow model. The fluid velocity field and particle distributions estimated from the mouth model were compared with those of the horizontal jet flow model. The significant effects of the airflow jet trajectory variations on the pattern of particle transport and dispersion during fricative utterances were studied. Distinct differences between the estimations of the horizontal jet model for particle propagation with those of the mouth model were observed. The importance of considering the vocal tract geometry and the failure of a horizontal jet model to properly estimate the expiratory airflow and respiratory particle propagation during the production of fricative utterances were emphasized.

Modeling an immune response to influenza A virus infection in alveolar epithelial cells

Influenza A viruses (IAV) have been the cause of several influenza pandemics in history and are a significant threat for the next global pandemic. Hospitalized influenza patients often have excess interferon production and a dysregulated immune response to the IAV infection. Obtaining a better understanding of the mechanisms of IAV infection that induce these harmful effects would help drug developers and health professionals create more effective treatments for IAV infection and improve patient outcomes. IAV stimulates viral sensors and receptors expressed by alveolar epithelial cells, like RIG-I and toll-like receptor 3 (TLR3). These two pathways coordinate with one another to induce expression of type III interferons to combat the infection. Presented here is a queuing theory-based model of these pathways that was designed to analyze the timing and amount of interferons produced in response to IAV single stranded RNA and double-stranded RNA detection. The model accurately represents biological data showing the necessary coordination of the RIG-I and TLR3 pathways for effective interferon production. This model can serve as the framework for future studies of IAV infection and identify new targets for potential treatments.

Tradeoff between the Brillouin and transverse mode instabilities in Yb-doped fiber amplifiers

The Brillouin instability (BI) due to stimulated Brillouin scattering (SBS) and the transverse (thermal) mode instability (TMI) due to stimulated thermal Rayleigh scattering (STRS) limit the achievable power in high-power lasers and amplifiers. The pump power threshold for BI increases as the core diameter increases, but the threshold for TMI may decrease as the core diameter increases. In this paper, we use a multi-time-scale approach to simultaneously model BI and TMI, which gives us the ability to find the fiber diameter with the highest power threshold. We formulate the equations to compare the thresholds of the combined and individual TMI and BI models. At the pump power threshold and below, there is a negligible difference between the full and individual models, as BI and TMI are not strong enough to interact with each other. The highest pump threshold occurs at the optimal core size of 43 µm for the simple double-clad geometry that we considered. We found that both effects contribute equally to the threshold, and the full BI and TMI model yields a similar threshold as the BI or TMI model alone. However, once the reflectivity is sufficiently large, we find in the full BI and TMI model that BI may trigger TMI and reduce the TMI threshold to a value lower than is predicted in simulations with TMI alone. This result cannot be predicted by models that consider BI and TMI separately. Our approach can be extended to more complex geometries and used for their optimization.

Combined CpG and MPL as vaccine adjuvants improve immunity and heterosubtypic protection against lethal viral challenge in single dose and prime/boost regimens

Current Influenza A virus (IAV) vaccines show poor efficacy, often 40–60%. A strategy to improve effectiveness of IAV vaccines is to include adjuvants to activate innate immunity. We examined the potential of combined pattern recognition receptor agonists CpG and MPL to increase IAV vaccine induced protection. When administered in a single, low dose intramuscular hemagglutinin (HA) protein vaccine, mice receiving MPL + CpG experienced less morbidity after homologous challenge compared to mice receiving single agonists. In experiments analyzing heterosubtypic protection, vaccines containing MPL delivered intramuscularly (i.m.) showed increased protection against weight loss while the addition of CpG enhanced antibody responses but not survival. To determine if MPL and CpG have combinatory effects at different sites, HA and NP were delivered with MPL i.m. while HA and NP were simultaneously delivered with CpG intranasally (i.n.). Data demonstrate that combination MPL i.m. + CpG i.n. abrogated morbidity, but did not improve survival compared to MPL + CpG i.m. Further, mice given MPL + CpG produced IgG antibodies that were cross-reactive to H1N1 virus, yet magnitude of antibody responses did not correlate with protective efficacy. Finally, comparison of MPL i.m. + CpG i.n. in a prime/boost regimen, followed by heterosubtypic challenge, showed that weight loss was significantly lowered in mice that received prime/boost vaccination compared to mice that received prime only. Higher antibody responses induced by a second dose of vaccine did not correlate with protective capacity, suggesting that antibody levels, while indicators of vaccine immunogenicity, do not directly correlate with ability to protect mice from severe disease.

Supported by Trudeau Institute and Clarkson University.

Validation of Ferret Luminex Cytokine Assays with serum from ferrets infected with flu, stimulated whole blood and PBMCs

Ferrets represent excellent models of infectious disease due to their natural susceptibility to many human respiratory viruses including influenza A virus (IAV), respiratory syncytial virus and severe acute respiratory syndrome (SARS). Ferrets can reproduce a similar course of disease and display similar symptoms of respiratory infection as humans, while mice do not exhibit key features of disease such as sneezing, nasal discharge and fever. There is pressing need to develop reagents to better understand and characterize the immune response to infection and support biomarker and countermeasure development through immunologic analyses of respiratory infections in the ferret. IL-1β, IL-2, IL-5, IL-6, IL-12 p40, IL-12p35, IL-17, IFNγ, TNFα, & IP-10 were expressed in HEK293 cells and purified. Monoclonal antibodies were generated and screened by Luminex for matched pairs to the recombinant protein and presumed positive samples. Capture antibodies were coupled to Luminex beads and detection antibodies were biotinylated. Serum from ferrets infected with flu had 10-fold higher levels of IP-10 and 3-fold higher levels of IL-6 than control serum. Stimulation of ferret whole blood with LPS showed increases in IL-2 and IL-6 at 2, 4 and 24 hrs. IL-12p40 and TNFα increased at 24hrs after stimulation with LPS. A validated cytokine panel in the study of immune related diseases in the ferret model.

Supported by SBIR contract 75N93020C00022: Development of Ferret Reagents for use in the Characterization of Immune Responses to Respiratory Infections in the Ferret Model

Variability in expiratory trajectory angles during consonant production by one human subject and from a physical mouth model: Application to respiratory droplet emission

The COVID-19 pandemic has highlighted the need to improve understanding of droplet transport during expiratory emissions. While historical emphasis has been placed on violent events such as coughing and sneezing, the recognition of asymptomatic and presymptomatic spread has identified the need to consider other modalities, such as speaking. Accurate prediction of infection risk produced by speaking requires knowledge of both the droplet size distributions that are produced, as well as the expiratory flow fields that transport the droplets into the surroundings. This work demonstrates that the expiratory flow field produced by consonant productions is highly unsteady, exhibiting extremely broad inter- and intra-consonant variability, with mean ejection angles varying from ≈+30° to -30°. Furthermore, implementation of a physical mouth model to quantify the expiratory flow fields for fricative pronunciation of [f] and [θ] demonstrates that flow velocities at the lips are higher than previously predicted, reaching 20-30 m/s, and that the resultant trajectories are unstable. Because both large and small droplet transport are directly influenced by the magnitude and trajectory of the expirated air stream, these findings indicate that prior investigations of the flow dynamics during speech have largely underestimated the fluid penetration distances that can be achieved for particular consonant utterances.

Accurate and efficient modeling of the transverse mode instability in high energy laser amplifiers

We study the transverse mode instability (TMI) in the limit where a single higher-order mode (HOM) is present. We demonstrate that when the beat length between the fundamental mode and the HOM is small compared to the length scales on which the pump amplitude and the optical mode amplitudes vary, TMI is a three-wave mixing process in which the two optical modes beat with the phase-matched component of the index of refraction that is induced by the thermal grating. This limit is the usual limit in applications, and in this limit TMI is identified as a stimulated thermal Rayleigh scattering (STRS) process. We demonstrate that a phase-matched model that is based on the three-wave mixing equations can have a large computational advantage over current coupled mode methods that must use longitudinal step sizes that are small compared to the beat length.

High- and low-molecular-weight chitosan act as adjuvants during single-dose influenza A virus protein vaccination through distinct mechanisms

The investigation of new adjuvants is essential for the development of efficacious vaccines. Chitosan (CS), a derivative of chitin, has been shown to act as an adjuvant, improving vaccine-induced immune responses. However, the effect of CS molecular weight (MW) on this adjuvanticity has not been investigated, despite MW having been shown to impact CS biological properties. Here, two MW variants of CS were investigated for their ability to enhance vaccine-elicited immune responses in vitro and in vivo, using a single-dose influenza A virus (IAV) protein vaccine model. Both low-molecular-weight (LMW) and high-molecular-weight (HMW) CS-induced interferon regulatory factor pathway signaling, antigen-presenting cell activation, and cytokine messenger RNA (mRNA) production, with LMW inducing higher mRNA levels at 24 h and HMW elevating mRNA responses at 48 h. LMW and HMW CS also induced adaptive immune responses after vaccination, indicated by enhanced immunoglobulin G production in mice receiving LMW CS and increased CD4 interleukin 4 (IL-4) and IL-2 production in mice receiving HMW CS. Importantly, both LMW and HMW CS adjuvantation reduced morbidity following homologous IAV challenge. Taken together, these results support that LMW and HMW CS can act as adjuvants, although this protection may be mediated through distinct mechanisms based on CS MW.

Active learning about the dynamic and complex nature of CD4+ T cell differentiation with computer network modeling and simulations

CD4+ T cells provide cell-mediated immunity in response to various antigens. During an immune response, naïve CD4+ T cells differentiate into specialized effector T helper cells (e.g., Th-1,-2,-17, etc.), and induced regulatory (iTreg) T cells. Their proper response to pathogens is governed by complex, non-linear dynamic networks consisting of various types of cells and their associated communication mediators (cytokines). The regulation of CD4+ T cell differentiation is a major topic of many post-secondary immunology-related courses.

However, the traditional lecture and textbook-based learning format in these (and other life sciences) courses makes it challenging for students to fully conceptualize and appreciate the complex and dynamic nature of such processes. We have developed a new learning approach that enables students to build, simulate, and investigate computational models of processes embedded in biological systems. This method is facilitated through an easy-to-use software, Cell Collective (https://cellcollective.org), that makes computational modeling accessible to any student and instructor (i.e., no prior computational modeling experience is necessary). The simulation lessons have been designed to be turn-key, self-contained, and adoptable by any instructor without the need to modify their syllabus, and with a minimal learning curve. They can be used in-class, assigned as homework, as well as deployed as extensive lab investigations. Here, we will present a new modeling and simulation lesson that enables students to learn about the dynamic complexities of CD4+ T cell differentiation, such as the effects of different cytokines and their dosage on the differentiation outcome, feedback loops, etc.

Combined CpG and MPL as vaccine adjuvants improve duration of protection induced by single dose influenza A virus protein vaccination

Despite vaccination, it is estimated more than 37 million people experienced influenza illness in the US during the 2018–19 season. Efficacy of the influenza A virus (IAV) vaccine may be improved with adjuvants that activate innate immunity. We examined the potential of combined pattern recognition receptor agonists CpG and MPL to increase vaccine induced protection. When administered with a single, low dose intramuscular hemagglutinin protein vaccine, mice receiving CpG+MPL experienced less weight loss after homologous challenge eight weeks after vaccination compared to mice receiving single agonists. However, when mice were challenged earlier after vaccination no significant improvements were observed in weight loss or viral titers, suggesting that combined CpG+MPL improves duration of protection. Despite not inducing excessive injection site damage, CpG+MPL elevated systemic inflammatory cytokines and chemokines 24 hours after vaccination compared to agonists alone. CpG and/or MPL increased monocyte derived migratory dendritic cell numbers and CD4 T cell proliferation in the draining lymph nodes (DLN) three days after vaccination. CpG+MPL also enhanced early T cell activation, measured by CD69 expression, in the DLN compared unadjuvanted vaccines. Additionally, at four weeks, mice vaccinated with CpG+MPL displayed a trend of elevated IgG2a/c antibody production compared to mice receiving single agonists. However, CD4 and CD8 T cell activation and cytokine production in the DLN after homologous challenge was not significantly impacted by CpG+MPL. Together these results suggest that CpG+MPL induces enhanced innate immune responses that contribute to extended duration of protection against homologous challenge.

Chitosan adjuvantation improves protection elicited by single, low dose influenza A virus recombinant protein vaccination

Continued development of effective vaccines requires investigation of new adjuvants that are able to direct and enhance immune responses. Adjuvants have potential to allow for fine-tuning of immune responses against pathogens for which vaccines are suboptimal, or non-existent. Despite this capability, few adjuvants are currently used in human vaccines. Biomaterials provide a pool of potential adjuvants that have been vetted for biocompatibility and adverse effects. One such material is chitosan (CS), a linear, positively charged, partially deacylated derivative of chitin. Varying molecular weights of CS were examined for their ability to improve influenza A virus vaccination. It was observed that mice receiving CS during single, low dose protein vaccination experienced significantly less weight loss after homologous challenge than mice receiving protein alone. CS elicited enhanced protection from weight loss was accompanied by elevated IgG and a trend of increased IgG1. When T cell activation was examined two days after challenge, CS adjuvantation resulted in no significant changes in IFN-γ or IL-4 production in the DLN, however CS induced IL-4 production by CD4 T cells in the lung at day five. This effect appeared to be dependent on the molecular weight of the CS. Additionally, CS adjuvantation resulted in elevated CD69+/CD103+ CD4 T cells in the lung two days after homologous challenge, potentially mediating improved protection against infection. Further, we observed enhanced in vitro cytokine production and IRF pathway activation in antigen presenting cells treated with CS. Taken together, these results suggest that CS is able to act as a vaccine adjuvant and may be used to instruct immune responses and improve vaccine efficacy.

In-class activities as formative assessments in immunology: student buy-in and utilization

Immunology is a difficult discipline to teach due to complex concepts, cellular interactions, jargon, and requirement of prerequisite knowledge across biology. Formative assessment (FA) techniques have been shown to improve student learning through increased engagement with material, instructor feedback, revision of understanding and student ownership of learning; yet implementation of these student-centered learning strategies can prove challenging. An in-class activity (ICA) worksheet FA was used in two semesters of an upper level Immunology course and a survey was used to measure student perception, buy-in and utilization of the FA. The ICA was administered each week and covered a key concept of the material presented. ICA worksheets examined the biochemical signaling pathways of T cell receptor signaling using an on line video by HHMI; HLA codominance and polygeny with flow cytometry data and Mendelian inheritance pedigrees; and CD4 T cell subset generation with an on-line modeling program developed by Cell Collective (www.cellcollective.org). Overall, student perceptions about ICA were favorable with a high level of “buy-in” across multiple categories/themes. In addition, ICA for immunology had a higher level of utilization (especially for later use) compared with other Biology courses using FAs. Within the immunology course, students viewed the ICA more favorable for later use and discussion compared to a pre-class FA, just in time teaching (JiTT). In contrast, students perceived the JiTT FA as providing more helpful feedback to correct misunderstandings. Utilizing student survey responses for both ICA and JiTT FAs will help improve in-class discussion, instructor feedback, and learning outcomes in immunology.

Analysis of Student Perceptions of Just-In-Time Teaching Pedagogy in PharmD Microbiology and Immunology Courses

Just-In-Time Teaching (JiTT) active learning pedagogy is utilized by various disciplines, but its value in a professional pharmacy curriculum has not yet been demonstrated. The purpose of our research study is to implement and evaluate JiTT in a Doctor of Pharmacy (PharmD) program. The impetus in implementing JiTT into a PharmD curriculum was to provide students with an out-of-classroom learning opportunity to enhance knowledge-based skills. The current study summarizes the implementation of JiTT in four distinct instances: two iterations of the required courses "Integrated Microbiology and Virology" (Fall 2016 and Fall 2017) and "Integrated Immunology" (Winter 2016-2017 and Winter 2017-2018). JiTT included knowledge-based questions in multiple-choice format, integrated case studies, and student responses prior to the actual lecture session. After the conclusion of each course, students were asked to provide feedback on the utilization of JiTT by way of an anonymous survey. Following the Fall 2016 iteration of the Microbiology & Virology course, students found the integrated case studies to be beneficial (mean = 3.27 out of a maximum of 4, SD = 0.62), and their overall endorsement of JiTT was high (mean = 3.61 out of 4, SD = 0.50). For the other three courses included in this study, the primary dependent variable was the student's average rating of JiTT, rated on a five-point scale. Aggregating the scores from the Fall 2017 iteration of the Integrated Microbiology & Virology course and both instances of the Immunology course, students rated JiTT very favorably (mean = 4.17 out of a maximum of 5, SD = 0.77). Students' performances in JiTT-based courses were compared against non-JiTT-based courses. Analysis of assessment data for student's performance on knowledge-based questions showed JiTT was helpful for student learning and JiTT-based courses had more consistent exam scores compared to non-JiTT-based courses. The current results are a promising initial step in validating the usefulness of JiTT in a pharmacy program and lays the foundation for future studies aimed at a direct comparison between a traditional lecture style and JiTT pedagogy implemented into PharmD curricula.

Non-complexed chitosan acts as an adjuvant in an influenza A virus protein vaccine

During the 2017–18 season influenza A virus (IAV) induced significant morbidity and mortality with the most recent vaccine estimated to be 36% effective in preventing illness. However, IAV vaccines may be improved through the use of adjuvants that enhance or direct specific immune responses. The biomaterial chitosan (CS), a partially deacetylated derivative of chitin, has been used in nucleic acid vaccine strategies for its ability to complex with DNA to form nanoparticles. However, we and others have found that non-complexed CS induces cell death and proinflammatory cytokine responses suggesting that non-complexed CS could act as an adjuvant to enhance immunity to protein vaccination. When bone marrow derived dendritic cells (BMDC) were treated with CS in vitro, we observed increased inflammatory cytokine gene expression, including IL-6. However, at high doses of CS the cytokine response was accompanied by BMDC death. Experiments using J774-Dual™ Cells, a mouse macrophage-like cell line with a Lucia luciferase reporter and a secreted embryonic alkaline phosphatase reporter under the Interferon regulatory factors (IRF) and NF-κB respectively, suggest that CS acts as an adjuvant by activating IRF and low levels of NF-κB. In vivo, when CS was administered with an i.m. protein vaccine, enhanced IgG antibody responses were observed at 3 and 4 weeks post vaccination. As CS is a polymer, the molecular weight (MW) may play a role in adjuvanticity. We have observed that MW may impact IRF and NF-κB activation in vitro, as well as antibody production in vivo. Experiments are underway to determine the level of protection afforded by the enhanced antibody production and to investigate if T cell responses can be augmented by modifying the vaccine regimen.

Just in Time Teaching (JiTT) Strategies: From Implementation to Student Buy-in

The Vision and Change in Undergraduate Biology Education calls for a transformation in instructional practices toward a more student-centered learning environment. Students in immunology courses can benefit from these strategies and one such approach, known as Just-in-Time Teaching (JiTT), is an inquiry based, active learning tactic that has been shown to enhance student retention of complex concepts. Prior to class, students read assignments and answer specific conceptual questions that involve linking new material or ideas with previously learned concepts. Importantly, an open-ended, reflective question is also asked about what students found most interesting, confusing, or difficult about the assignment. JiTT assignments have a positive impact on learning by allowing students to prepare ahead and use real life applications to better understand the material. Accordingly, the most successful JiTT assignments are questions based on the Case Studies in Immunology, 7th edition (Raif Geha and Luigi Notarangelo), that indicate which concepts are being discussed for each case. Overall, the JiTT approach has been well-received for upper level Immunology students. Results from formative assessment surveys generated by discipline based educational researchers (DBER) in our department in 2017 and 2018 indicate that most students understand the value of JiTT to enhance their learning, however, some students believe that assessments should always come after lecture, not before. Students agree that JiTT questions give them feedback on what material is important and what they still need to learn. Utilizing these surveys will help improve the messaging, learning intentions and overall student buy-in for future iterations of the course.

Oral Non-Viral Gene Delivery for Applications in DNA Vaccination and Gene Therapy

Non-viral gene delivery via the oral route is a promising strategy for improving outcomes of DNA vaccination and gene therapy applications. Unlike traditional parenteral administration routes, the oral route is a non-invasive approach that lends itself to high patient compliance and ease of dosing. Moreover, oral administration allows for both local and systemic production of therapeutic genes or, in the case of DNA vaccination, mucosal and systemic immunity. However, the oral route presents distinct challenges and barriers to achieving successful gene delivery. Oral non-viral gene delivery systems must be able to survive the harsh and variable environments (e.g. acidic pH, degrading enzymes, mucus layer) encountered during transit through the gastrointestinal tract, while still allowing for efficient transgene production at sites of interest. These barriers present unique design challenges for researchers in material selection and in improving the transfection efficiency of orally delivered genes. This review provides an overview of advancements in the design of oral non-viral gene delivery systems, and highlights recent and important developments towards improving orally delivered genes for applications in gene therapy and DNA vaccination.

A Mechanistic Computational Model Reveals That Plasticity of CD4+ T Cell Differentiation Is a Function of Cytokine Composition and Dosage

CD4⁺ T cells provide cell-mediated immunity in response to various antigens. During an immune response, naïve CD4⁺ T cells differentiate into specialized effector T helper (Th1, Th2, and Th17) cells and induced regulatory (iTreg) cells based on a cytokine milieu. In recent studies, complex phenotypes resembling more than one classical T cell lineage have been experimentally observed. Herein, we sought to characterize the capacity of T cell differentiation in response to the complex extracellular environment. We constructed a comprehensive mechanistic (logical) computational model of the signal transduction that regulates T cell differentiation. The model's dynamics were characterized and analyzed under 511 different environmental conditions. Under these conditions, the model predicted the classical as well as the novel complex (mixed) T cell phenotypes that can co-express transcription factors (TFs) related to multiple differentiated T cell lineages. Analyses of the model suggest that the lineage decision is regulated by both compositions and dosage of signals that constitute the extracellular environment. In this regard, we first characterized the specific patterns of extracellular environments that result in novel T cell phenotypes. Next, we predicted the inputs that can regulate the transition between the canonical and complex T cell phenotypes in a dose-dependent manner. Finally, we predicted the optimal levels of inputs that can simultaneously maximize the activity of multiple lineage-specifying TFs and that can drive a phenotype toward one of the co-expressed TFs. In conclusion, our study provides new insights into the plasticity of CD4⁺ T cell differentiation, and also acts as a tool to design testable hypotheses for the generation of complex T cell phenotypes by various input combinations and dosages.

Molecular characterization of combination pattern recognition receptor agonist exposure on dendritic cell responses

Current Influenza A virus (IAV) vaccines induce antibody formation and therefore fail to induce heterosubtypic protection needed to overcome viral antigenic shift and drift. New vaccine strategies have used pattern recognition receptor (PRR) agonists as adjuvants to improve both B and T cell memory; however, the effect of using combined PRR agonists on vaccine induced memory is unknown. We have demonstrated that vaccination with hemagglutinin (HA) antigen with combined TLR4 and TLR9 agonists promotes protection from lethal infection more effectively than either agonist alone or HA with the oil-in-water adjuvant Addavax. To begin to dissect the molecular changes that occur in dendritic cells exposed to combination agonists, we used qPCR, multiplex assays and RNA-seq analysis to characterize the changes in gene expression in response to combined TLR4 and TLR9 stimulation. We found low dose TLR4 and TLR9 agonists in combination could enhance IL-6, IFN-β and CCL4 mRNA over either agonist alone. Analysis of in vivo early cytokine responses 6 hours post intramuscular vaccination, corroborated in vitro results, demonstrating increased levels of serum IL-6, TNF-α, CCL4 and CCL2 in response to combined agonists. To further probe the mechanistic basis for increased protection with combined agonists, transcriptome analysis was performed on dendritic cells after treatment with single or combination TLR4 and TLR9 agonists. Genes such as CXCL10, IL-12 and a number of interferon stimulated genes (ISGs) were shown to be increased following combination agonist stimulation. Further, gene ontology analysis and ingenuity pathway analysis will be performed to gain insight into the complex regulation and mechanism of dual TLR4 and TLR9 agonists.

Pattern recognition receptor agonists enhance protection elicited by a single, low dose protein vaccine in an immunization route-specific manner

Despite advances to increase vaccine efficacy, influenza A virus (IAV) remains a significant health risk. Current vaccines against IAV rely on the generation of strain specific antibodies that fail to provide protection against heterosubtypic IAV. Vaccination may be improved through the use of vaccine adjuvants to amplify antigen presenting cell (APC) activation and enhance T and B cell priming. Combined adjuvants that trigger multiple pattern recognition receptors (PRR) are a promising strategy to better mimic live infection. In this study, the efficacy of combining CpG and MPLA, which activate TLR9 and TLR4 respectively, as vaccine adjuvants was examined. It was observed that single, low dose hemagglutinin (HA) protein vaccines containing combination CpG and MPLA delivered intramuscularly (i.m.) or intranasally (i.n.) elicit superior protection against lethal challenge compared to vaccines containing single agonists, as indicated by lower mortality and significantly lower morbidity. Early systemic cytokine responses are being investigated to elucidate the mechanism behind this improved vaccine efficacy. However, it was observed that i.m. administration of combination agonist vaccines induced higher IgG2c antibody responses compared to single agonist vaccines, while minimal levels of antibodies were observed in mice vaccinated i.n. In addition, T cell analysis following lethal infection indicated that i.n. vaccination induces distinct activation profiles compared to i.m. Taken together a comparison of the antibody and T cell profiles of mice vaccinated i.m. and i.n with combined TLR9 and TLR4 agonists suggests that route of vaccination can dictate immune response and may modify effective correlates of protection.

Just-In-Time Active Learning Instructional Pedagogy for PharmD Integrated Immunology Course

Just-In-Time Teaching (JiTT) is an active learning pedagogy that has been successfully adopted by various disciplines. Our previous studies showed that JiTT presents value to a pharmacy curriculum. The current study implemented JiTT as an active-learning tool for an Integrated Immunology course offered during the first year of a PharmD program. At the end of the course, 38 students provided feedback on a survey that asked for their degree of agreement to various statements about JiTT usage in the course: 18 items were phrased positively (e.g., “Overall, JiTT questions are beneficial to me”), and 4 items were phrased negatively (e.g., “JiTT made the course more difficult”). These statements were rated on a scale ranging from 1 (strongly disagree) to 5 (strongly agree). The aggregate raw score for the 4 negatively-phrased items (M = 2.20, SD = 0.80) suggests that, overall, students typically disagreed with negatively-phrased statements about JiTT. After the negatively-phrased items were reverse-coded, all items were aggregated into a single measure (Cronbach’s alpha = .95) such that higher scores indicate positive overall perceptions of JiTT. This overall mean score for the survey indicates that students strongly perceive JiTT as beneficial (M = 4.00, SD = 0.84). Our results suggest that students in a pharmacy program perceive JiTT to be beneficial and valuable.

Activation of IRF3 contributes to IFN-γ and ISG54 expression during the immune responses to B16F10 tumor growth

Interferon Regulatory Factor (IRF-3) has been shown to contribute to immune control of B16 melanoma tumor growth. We have shown previously that IRF-3 has a role in IFN-γ-induced expression of pro-apoptotic interferon stimulated gene 54 (ISG54) in macrophages and IFN-γ in T cells. To investigate the IRF3-IFN-γ-ISG54 nexus, we injected C57Bl/6 (B6) and IRF3KO mice s.c. with luciferase-producing B16-F10 tumor cells. Tumor growth as measured by luciferase levels was similar between B6 and IRF3KO mice at days 2 and 6, but was significantly greater at day 9 in IRF3KO mice compared with B6 mice. Transcription factor assays on splenic protein extracts after tumor inoculation revealed peak activation of IRF3 and IRF7 at day 6 in B6 tumor-bearing mice but not in IRF3KO tumor-bearing mice. Likewise, significant induction of IFN-γ occurred in spleens and tumors in B6 mice from days 6-9 but failed to occur in tumor-bearing IRF3KO mice. Previous reports from other labs showed that the anti-tumor properties of IFN-γ are the result of cell cycle arrest. Using B16F1 cells or B16F1 cells deficient in IFN-γ receptor (B16-IRFGRKO), we found that IFN-γ alone and in synergy with the TLR3/IRF3 agonists, poly I:C, decreased B16F1 cell growth in significant correlation with increased ISG54 expression. Moreover, IFN-γ alone increased expression of the cell cycle inhibitor, p27Kip while IFN-γ plus poly I:C increased cleaved Caspase-3 in B16 cells. Thus, it is likely that an IFN-γ/IRF3/ISG54 nexus can significantly contribute to tumor cell control during anti-tumor immune responses.

Chitosan nanoparticle delivery of Influenza A Virus DNA vaccine enhances antibody class switching and abrogates weight loss post IAV challenge

DNA vaccination presents a promising new approach for Influenza A Virus (IAV) vaccines, as they can be generated quickly in response to the viral antigenic shift and drift characteristic of IAV pandemic outbreaks. A DNA vaccination approach for IAV was examined using a plasmid encoding PR8 H1N1 hemagglutinin (HA) protein as a potential IAV vaccine. In addition to the HA antigen sequence the plasmid also encoded a sequence that when transcribed, activates the pattern recognition receptor RIG-I, improving innate immune activation. To increase the potential of this IAV DNA vaccine, our study focused on delivery of the plasmid to the respiratory tract using chitosan (CS) nanoparticles. CS, a mucoadhesive/mucopenetrating derivative of chitin, forms complexes with DNA to improve uptake and transfection of the plasmid by immune cells in the lung. In vitro, plasmid/CS complexes containing unbound CS induced bone marrow derived dendritic cell (BMDC) death. BMDC death was accompanied by a robust increase in inflammatory cytokine mRNA. Although BMDC death was abrogated by free CS removal, cytokine expression was also reduced. Alternative complexation methods are being explored to achieve an appropriate balance between cytokine production and cell death. In vivo intranasal prime-boost vaccination with low dose PR8 HA plasmid/CS nanoparticles resulted in PR8 specific IgM and total IgG antibody formation. Although weight loss was abrogated in plasmid/CS vaccinated mice, protection from lethal PR8 infection did not correlate with antibody level. By optimizing this vaccine approach, including dose, regime, and CS nanoparticle modification, critical insights into the development of rapidly deployable IAV vaccines could be gained.

Implementation and student perceptions of the Just in Time Teaching (JiTT) strategy in an upper level immunology course

Instructional pedagogy has undergone innovative changes to meet the demands of 21st century science education. One such teaching strategy, known as Just-in-Time Teaching or JiTT, is an inquiry based, active learning approach that evolved to meet those demands and has been shown to enhance student retention of complex concepts. Prior to class, students read assignments and answer specific conceptual questions that involve linking new material or ideas with previously learned concepts. Importantly, an open-ended, reflective question is also asked about what students found most interesting, confusing, or difficult about the particular assignment. Student responses to these conceptual and reflective questions help identify incoming misconceptions and are used during class to modify instruction and facilitate discussion. Students are graded based on effort, rather than complete correctness, as “low stakes” assessments have been shown to increase student participation and encourage inquiry. Some of the most successful JiTTs in my course are based on the Case Studies in Immunology companion book to Janeway’s ImmunoBiology. These case studies introduce topics such as the importance of MHC molecules in the development of specific CD8 or CD4 T cells. Additional examples will be given that demonstrate the breadth and scope of JiTT concepts and questions as well as student responses to JiTT assessments. Finally, results from a student survey will be presented to demonstrate how students perceive the JiTT strategy to support their learning. Overall, the JiTT approach has been well-received for upper level Immunology students and is beneficial to student and instructor to assess understanding of complex biological concepts.

Combination CpG and MPL agonists heighten vaccine-induced protection against Influenza A virus challenge

Current strategies for Influenza A Virus (IAV) vaccination result in antibodies against strain specific viral coat proteins. These antibodies do not provide protection against heterologous IAV strains and leave the population vulnerable to pandemics of highly pathogenic IAV. Vaccines may be improved by targeting T cells, which unlike B cells, are able to recognize inner, conserved IAV antigens, such as nucleoprotein (NP), increasing the potential for protection against different IAV stains. During live IAV infection multiple pattern recognition receptors (PRRs) on innate immune cells are activated; therefore vaccines triggering multiple PRRs may elicit better protection. As dendritic cells are the most potent antigen presenting cells for T cells, bone marrow derived dendritic cells (BMDCs) were activated by combined agonists that trigger separate, yet complementary PRR signaling pathways. Here we show that combined PRR agonists MPL and CpG, which activate TLR4 and TLR9 respectively, increased in vitro cytokine and chemokine expression by BMDCs. Further, intramuscular vaccination of mice with IAV pdm09 H1N1 hemagglutinin (HA) protein plus combined CpG and MPL, as adjuvants, induced the formation of pdm09 HA specific IgG2c antibodies. Combined CpG and MPL recipient mice experienced less weight loss and lower mortality after lethal challenge with pdm09 H1N1 compared to mice receiving lone agonists, suggesting that combined agonists improve protection. T cell activation in response to combined CpG and MPL is currently being investigated, as well as responses generated via mucosal, intranasal vaccination. Thus combined agonists that promote B and T cell mediated immunity could be incorporated into next generation IAV vaccines.

IRF3 contributes to IFN-γ expression during B16F10 tumor growth and also IFN-γ-dependent reduction in B16 tumor cell growth

Previously, we reported in C57Bl/6 (B6) and IRF3KO mice that Interferon Regulatory Factor (IRF-3) contributes to control of B16 melanoma tumor growth. Moreover we found a link between IRF-3 and expression of IFN-γ during in vitro T cell responses of B6 and IRF3KO mice. To investigate IRF3 and IFN-γ expression at growing tumors, we injected B6 and IRF3KO mice sq with B16-F10 tumor cells that constitutively express luciferase. Tumor growth was similar between B6 and IRF3KO mice at day 2 and 6, but was significantly greater at day 9 in IRF3KO mice compared with B6 mice. Using transcription factor assays of spleen extracts, IRF3 and IRF7 activation peaked at day 6 in B6 tumor-bearing mice but failed to occur in IRF3KO mice post injection. Likewise, significant induction of IFN-γ occurred in spleens and tumors in tumor-bearing B6 mice but failed to occur in tumor-bearing IRF3KO mice from day 6–9 post injection. Previous reports from other labs showed that the anti-tumor properties of IFN-γ are the result of G1/G0 cell cycle arrest. Using B16 cells or B16 cells deficient in IFN-γ receptor (B16-IRFGRKO), we found that IFN-γ decreases B16 tumor cell growth and synergizes with the TLR3/IRF3 agonists, poly I:C, in decreasing B16 cell growth. Concomitantly, IFN-γ induced interferon stimulated gene-54 (ISG54), which is IRF3 dependent and promotes apoptosis in cells. Moreover, we treated B16-SEAP and B16-SEAPIFNGRKO cells, which express secreted alkaline phosphatase (SEAP) under the control of an ISG54/ISRE promoter. We found that IFN-γ induces ISG54 promoter activity and poly I:C synergizes with IFN-γ to induce ISG54 in B16 cells. Thus an IFN-γ/IRF3/ISG54 nexus can significantly contribute to tumor cell control during anti-tumor immune responses.

Implementation of just-in-time teaching strategy as an active learning instructional pedagogy for PharmD integrated microbiology and virology course

Just-In-Time Teaching (JiTT) is an active learning pedagogy that has been successfully adopted by various disciplines. However, it is unclear if JiTT presents value to a pharmacy curriculum. The current study implemented JiTT as an active-learning tool for an Integrated Microbiology and Virology course offered during the first year of a PharmD program. At the end of the course, students were provided with a survey that included items about JiTT. Several items were aggregated into a single rating about the degree that students agreed with various statements purporting JiTT as helpful, with score choices ranging from 1 (I strongly disagree) to 4 (I strongly agree). Overall, students strongly endorsed JiTT as helpful (M = 3.61, SD = 0.50), and even the lowest score, 2.50, was neutral in tone. Students were asked to endorse rationales for why JiTT questions were used in this course; 93.02% felt that JiTT helped them keep track with the material, and only 34.88% felt that JiTT gave them “extra work.” These results—and other findings stated in the poster —suggest that students in a pharmacy program find value in JiTT.

Synergistic enhancement of ISG54/ISRE promoter activity with combinations of Pattern Recognition Receptor agonists and Interferon-gamma

Induction of interferon stimulated genes (ISG)-54, which depends on activation of Interferon Regulatory Factor 3 (IRF-3), is critical for innate immune responses of virus-infected cells by reducing cell viability through the intrinsic apoptosis pathway. Using wild type (WT) and IRF3 deficient (IRF3KO) RAW 264.7 cell lines, genetically engineered to express secreted Lucia luciferase under control of an ISG54/ISRE promoter (RAW-Lucia), we saw that ISG54 promoter activity is IRF3 dependent in response to IFN-γ. To investigate IRF3 in responses to IFN-γ, WT and IRF3KO RAW-Lucia cells were stimulated with IFN-γ in the presence or absence of the IRF-3 agonist, Polyinosinic-Polycytidylic acid (PolyI:C). IFN-γ and PolyI:C synergistically enhanced ISG54/ISRE promoter activity in both WT and IRF3KO RAW-Lucia cells, however, this activity was 91% lower in IRF3KO compared to WT cells. Moreover, ISG54 promoter activity was negatively correlated with viability of WT RAW-Lucia. RAW-Lucia cells also responded in a similar fashion when stimulated with IFN-γ plus transfected PolyI:C or dA:dT, which are RIG-I/MDA-5 and STING agonists, respectively. Co-stimulation with IFN-γ and TLR7 agonist, Loxoribine-which activates IRF7 but not IRF3-also synergistically enhanced ISG54/ISRE promoter activity in WT and IRF3KO RAW-Lucia cells, but IRF3 deficiency reduced the synergistic enhancement of ISG54/ISRE promoter activity by 92%. In contrast, the TLR9 agonists, ODN1585, which also activates IRF7 but not IRF3, failed to stimulate ISG54/ISRE promoter activity in RAW-Lucia cells and only enhanced the response to IFN-γ by 30%. These studies further reveal a previously unnoticed IFN-γ/IRF3/ISG54 nexus that can be exploited for antiviral therapy.

Chitosan-zein nano-in-microparticles capable of mediating in vivo transgene expression following oral delivery

The oral route is an attractive delivery route for the administration of DNA-based therapeutics, specifically for applications in gene therapy and DNA vaccination. However, oral DNA delivery is complicated by the harsh and variable conditions encountered throughout gastrointestinal (GI) transit, leading to degradation of the delivery vector and DNA cargo, and subsequent inefficient delivery to target cells. In this work, we demonstrate the development and optimization of a hybrid-dual particulate delivery system consisting of two natural biomaterials, zein (ZN) and chitosan (CS), to mediate oral DNA delivery. Chitosan-Zein Nano-in-Microparticles (CS-ZN-NIMs), consisting of core Chitosan/DNA nanoparticles (CS/DNA NPs) prepared by ionic gelation with sodium tripolyphosphate (TPP), further encapsulated in ZN microparticles, were formulated using a water-in-oil emulsion (W/O). The resulting particles exhibited high CS/DNA NP loading and encapsulation within ZN microparticles. DNA release profiles in simulated gastric fluid (SGF) were improved compared to un-encapsulated CS/DNA NPs. Further, site-specific degradation of the outer ZN matrix and release of transfection competent CS/DNA NPs occurred in simulated intestinal conditions with CS/DNA NP cores successfully mediating transfection in vitro. Finally, CS-ZN-NIMs encoding GFP delivered by oral gavage in vivo induced the production of anti-GFP IgA antibodies, demonstrating in vivo transfection and expression. Together, these results demonstrate the successful formulation of CS-ZN-NIMs and their potential to improve oral gene delivery through improved protection and controlled release of DNA cargo.

Significant role for IRF3 in both T cell and APC effector functions during T cell responses

Interferon Regulatory Factor (IRF)3 is a crucial transcription factor during innate immune responses. Here we show IRF3 also has a role in adaptive T cell immune responses. Expression of IFN-γ, IL-17, and Granzyme B (GrB) during in vitro T cell responses was impaired when either dendritic cells (DCs) or T cells were derived from IRF3KO mice. Unexpectedly, IRF3-dependent NK-activating molecule (INAM), which is an NK cell activating factor of the DC innate immune response, was induced during the T cell response. Additionally, supernatants from responding T cells induced ISG54 in the RAW264.7 macrophage cell line in an IRF3 dependent manner. Moreover, addition of anti-IFN-γ prevented supernatant induction of ISG54 and recombinant IFN-γ stimulated ISG54 expression. Thus, IRF3 in APCs and T cells is required for optimal T-cell effector function and the ability of T cells to influence innate immune function of APCs.

Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) and serine biosynthetic pathway genes are co-ordinately increased during anabolic agent-induced skeletal muscle growth

We aimed to identify novel molecular mechanisms for muscle growth during administration of anabolic agents. Growing pigs (Duroc/(Landrace/Large-White)) were administered Ractopamine (a beta-adrenergic agonist; BA; 20 ppm in feed) or Reporcin (recombinant growth hormone; GH; 10 mg/48 hours injected) and compared to a control cohort (feed only; no injections) over a 27-day time course (1, 3, 7, 13 or 27-days). Longissimus Dorsi muscle gene expression was analyzed using Agilent porcine transcriptome microarrays and clusters of genes displaying similar expression profiles were identified using a modified maSigPro clustering algorithm. Anabolic agents increased carcass (p = 0.002) and muscle weights (Vastus Lateralis: p < 0.001; Semitendinosus: p = 0.075). Skeletal muscle mRNA expression of serine/one-carbon/glycine biosynthesis pathway genes (Phgdh, Psat1 and Psph) and the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase-M (Pck2/PEPCK-M), increased during treatment with BA, and to a lesser extent GH (p < 0.001, treatment x time interaction). Treatment with BA, but not GH, caused a 2-fold increase in phosphoglycerate dehydrogenase (PHGDH) protein expression at days 3 (p < 0.05) and 7 (p < 0.01), and a 2-fold increase in PEPCK-M protein expression at day 7 (p < 0.01). BA treated pigs exhibit a profound increase in expression of PHGDH and PEPCK-M in skeletal muscle, implicating a role for biosynthetic metabolic pathways in muscle growth.

The Candida albicans quorum-sensing molecule, farnesol, remodels the peritoneal cavity microenvironment to promote innate inflammatory responses in mice

Candida albicans is a polymorphic fungus that causes mucosal candidiasis and life threatening, systemic and intra-abdominal disease in immunocompromised and transplant patients. In normal healthy adults, C albicans is maintained as a commensal mainly through the actions of innate cells. Secretion of the quorum-sensing molecule, farnesol, acts as a virulence factor for C. albicans during systemic infection, but is protective in oral models of infection. Despite the clinical importance of intra-abdominal candidiasis with a mortality rate as high as 65%, the role of farnesol in its pathogenesis has not been studied. In ongoing experiments, we found that introduction of farnesol into the peritoneal cavity (PC) of mice remodels the peritoneal microenvironment to promote innate inflammatory responses. Early following intraperitoneal injection, farnesol stimulates the rapid depletion of B cells followed by recruitment of inflammatory macrophages and neutrophils into the PC compared to thioglycollate and control mice. Kinetic analyses of the transcriptional profile of farnesol-elicited cells reveal an early increase in chemokines followed by increased proinflammatory cytokines consistent with macrophage recruitment and activation. In addition, farnesol-elicited macrophages and dendritic cells demonstrate hallmarks of innate immune activation through high surface expression of class II and co-stimulatory molecules.

Current experiments aim to determine the impact of this innate immune recruitment on antifungal defenses and clearance in the PC. Defining the immunostimulatory properties of farnesol will inform development of more appropriate therapeutic strategies for treatment of intra-abdominal Candida infection.

Antigen presenting cell subsets in the lung and draining lymph nodes affect granzyme B-expressing CD4+ T cells in the lung during influenza A infection

Influenza A virus (IAV) is a global health burden that evades vaccine responses and can present as a pandemic threat. Innate immune cells are the first line of defense at the mucosal site of entry and drive adaptive responses that provide immunity. Therefore, we examined the distinct antigen-presenting cell (APC) populations in the lung and draining lymph nodes that respond to IAV infection. When mice are treated intranasally with PR8, a highly inflammatory H1N1 IAV, the populations of APCs in the lung change, inducing infiltration of a large population of inflammatory macrophages and a concomitant decrease in dendritic cells. These inflammatory macrophages express increased levels of TLR9 after infection, corresponding with our previous work demonstrating the efficacy of CpG DNA in driving anti-IAV responses. These changes in APC subsets do not occur in a similar fashion after infection with X31, a low inflammation H3N2 virus, or in the lymph nodes. One significant response is the production of granzyme B (GzB) in CD4+ T cells that infiltrate the lung after IAV infection. APC populations were sorted after PR8 infection and used to stimulate DO11.10 T cells in vitro. CD11b+ APCs were most efficient at inducing GzB in CD4+ T cells in steady-state, while after infection both CD11b+ and CD11b+CD11c+ APCs induced strong GzB expression, while all APC subsets induced IL-2 and IFN-gamma release from CD4+ T cells. These results have implications for vaccine design and we are currently utilizing chimeric antibodies to target antigen to APC populations in the lung and lymph nodes to induce anti-IAV CD4+ T cell responses.

Micro- and nanoparticulates for DNA vaccine delivery

DNA vaccination has emerged as a promising alternative to traditional protein-based vaccines for the induction of protective immune responses. DNA vaccines offer several advantages over traditional vaccines, including increased stability, rapid and inexpensive production, and flexibility to produce vaccines for a wide variety of infectious diseases. However, the immunogenicity of DNA vaccines delivered as naked plasmid DNA is often weak due to degradation of the DNA by nucleases and inefficient delivery to immune cells. Therefore, biomaterial-based delivery systems based on micro- and nanoparticles that encapsulate plasmid DNA represent the most promising strategy for DNA vaccine delivery. Microparticulate delivery systems allow for passive targeting to antigen presenting cells through size exclusion and can allow for sustained presentation of DNA to cells through degradation and release of encapsulated vaccines. In contrast, nanoparticle encapsulation leads to increased internalization, overall greater transfection efficiency, and the ability to increase uptake across mucosal surfaces. Moreover, selection of the appropriate biomaterial can lead to increased immune stimulation and activation through triggering innate immune response receptors and target DNA to professional antigen presenting cells. Finally, the selection of materials with the appropriate properties to achieve efficient delivery through administration routes conducive to high patient compliance and capable of generating systemic and local (i.e. mucosal) immunity can lead to more effective humoral and cellular protective immune responses. In this review, we discuss the development of novel biomaterial-based delivery systems to enhance the delivery of DNA vaccines through various routes of administration and their implications for generating immune responses.

The Differentiation and Protective Function of Cytolytic CD4 T Cells in Influenza Infection

CD4 T cells that recognize peptide antigen in the context of class II MHC can differentiate into various subsets that are characterized by their helper functions. However, increasing evidence indicates that CD4 cells with direct cytolytic activity (CD4 CTL) play a role in chronic as well as acute infections, such as influenza A virus (IAV) infection. In the last couple of decades, techniques to measure the frequency and activity of these cytolytic cells has demonstrated their abundance in infections, such as human immunodeficiency virus, mouse pox, murine gamma herpes virus, cytomegalovirus, Epstein-Barr virus, and influenza among others. We now appreciate a greater role for CD4 CTL as direct effectors in viral infections and antitumor immunity through their ability to acquire perforin-mediated cytolytic activity and contribution to lysis of virally infected targets or tumors. As early as the 1980s, CD4 T cell clones with cytolytic potential were identified after influenza virus infection, yet much of this early work was dependent on in vitro culture and little was known about the physiological relevance of CD4 CTL. Here, we discuss the direct role CD4 CTL play in protection against lethal IAV infection and the factors that drive the generation of perforin-mediated lytic activity in CD4 cells in vivo during IAV infection. While focusing on CD4 CTL generated during IAV infection, we pull comparisons from the literature in other antiviral and antitumor systems. Further, we highlight what is currently known about CD4 CTL secondary and memory responses, as well as vaccination strategies to induce these potent killer cells that provide an extra layer of cell-mediated immune protection against heterosubtypic IAV infection.

The global variability of diatomaceous earth toxicity: a physicochemical and in vitro investigation

Background

Diatomaceous earth (DE) is mined globally and is potentially of occupational respiratory health concern due to the high crystalline silica content in processed material. DE toxicity, in terms of variability related to global source and processing technique, is poorly understood. This study addresses this variability using physicochemical characterisation and in vitro toxicology assays.

Methods

Nineteen DE samples sourced from around the world, comprising unprocessed, calcined and flux-calcined DE, were analysed for chemical and mineral composition, particle size and morphology, and surface area. The potential toxicity of DE was assessed by its haemolytic capacity, and its ability to induce cytotoxicity or cytokine release by J774 macrophages.

Results

The potential toxicity of DE varied with source and processing technique, ranging from non-reactive to as cytotoxic and haemolytic as DQ12. Crystalline silica-rich, flux-calcined samples were all unreactive, regardless of source. The potential toxicity of unprocessed and calcined samples was variable, and did not correlate with crystalline silica content. Calcium-rich phases, iron content, amorphous material, particle size and morphology all appeared to play a role in sample reactivity. An increased surface area was linked to an increased reactivity in vitro for some sample types.

Conclusions

Overall, no single property of DE could be linked to its potential toxicity, but crystalline silica content was not a dominant factor. Occlusion of the potentially toxic crystalline silica surface by an amorphous matrix or other minerals and impurities in the crystal structure are suggested to pacify toxicity in these samples. In vivo verification is required, but these data suggest that crystalline silica content alone is not a sufficient indicator of the potential DE hazard.

Electronic supplementary material

The online version of this article (doi:10.1186/s12995-015-0064-7) contains supplementary material, which is available to authorized users.

Single-Dose CpG Immunization Protects Against a Heterosubtypic Challenge and Generates Antigen-Specific Memory T Cells

Despite extensive research, influenza A virus (IAV) remains a major cause of morbidity, mortality, and healthcare expenditure. Emerging pandemics from highly pathogenic IAV strains, such as H5N1 and pandemic H1N1, highlight the need for universal, cross-protective vaccines. Current vaccine formulations generate strain-specific neutralizing antibodies primarily against the outer coat proteins, hemagglutinin and neuraminidase. In contrast to these highly mutable proteins, internal proteins of IAV are more conserved and are a favorable target for developing vaccines that induce strong T cell responses in addition to humoral immunity. Here, we found that intranasal administration with a single dose of CpG and inactivated x31 (H3N2) reduced viral titers and partially protected mice from a heterosubtypic challenge with a lethal dose of PR8 (H1N1). Early after immunization, vaccinated mice showed increased innate immune activation with high levels of MHCII and CD86 expression on dendritic cells in both draining lymph nodes and lungs. Three days after immunization, CD4 and CD8 cells in the lung upregulated CD69, suggesting that activated lymphocytes are present at the site of vaccine administration. The ensuing effector Th1 responses were capable of producing multiple cytokines and were present at least 30 days after immunization. Furthermore, functional memory responses were observed, as antigen-specific IFN-γ⁺ and GrB⁺ cells were detected early after lethal infection. Together, this work provides evidence for using pattern recognition receptor agonists as a mucosal vaccine platform for inducing robust T cell responses capable of protecting against heterologous IAV challenges.

IRF3 deficiency impacts granzyme B expression and maintenance of memory T cell function in response to viral infection

The role of interferon regulatory factor 3 (IRF3) in the innate immune response to infection has been well studied. However, less is known about IRF3 signaling in shaping the adaptive T cell response. To determine the role of IRF3 in the generation and maintenance of effective anti-viral T cell responses, mice deficient in IRF3 were infected with a potentially persistent virus, Theiler's murine encephalomyelitis virus (TMEV) or with a model acute infection, influenza A virus (IAV). IRF3 was required to prevent TMEV persistence and induce robust TMEV specific effector T cell responses at the site of infection. This defect was more pronounced in the memory phase with an apparent lack of TMEV-specific memory T cells expressing granzyme B (GrB) in IRF3 deficient mice. In contrast, IRF3 had no effect on antigen specific T cell responses at the effector stage during IAV infection. However, memory T cell responses to IAV were also impaired in IRF3 deficient mice. Furthermore, addition of cytokines during peptide restimulation could not restore GrB expression in IRF3 deficient memory T cells. Taken together, IRF3 plays an important role in the maintenance of effective anti-viral T cell memory responses.

Toxicological effect of engineered nanomaterials on the liver

The liver has a crucial role in metabolic homeostasis, as it is responsible for the storage, synthesis, metabolism and redistribution of carbohydrates, fats and vitamins, and numerous essential proteins. It is also the principal detoxification centre of the body, removing xenobiotics and waste products by metabolism or biliary excretion. An increasing number of studies have shown that some nanomaterials (NMs) are capable of distributing from the site of exposure (e.g. lungs, gut) to a number of secondary organs, including the liver. As a secondary exposure site the liver has been shown to preferentially accumulate NMs (>90% of translocated NMs compared with other organs), and alongside the kidneys may be responsible for the clearance of NMs from the blood. Research into the toxicity posed by NMs to the liver is expanding due to the realization that NMs accumulate in this organ following exposure via a variety of routes (e.g. ingestion, injection and inhalation). Thus it is critical to consider what advances have been made in the investigation of NM hepatotoxicity, as well as appraising the quality of the information available and gaps in the knowledge that still exist. The overall aim of this review is to outline what data are available in the literature for the toxicity elicited by NMs to the liver in order to establish a weight of evidence approach (for risk assessors) to inform on the potential hazards posed by NMs to the liver.

Early cytokine dysregulation and viral replication are associated with mortality during lethal influenza infection

Infection with influenza A virus (IAV) leads to acute lung injury and possibly fatal complications, especially in immunocompromised, elderly, or chronically infected individuals. Therefore, it is important to study the factors that lead to pathology and mortality in infected hosts. In this report, we analyze immune responses to infection at a sublethal (0.1 LD(50)) and lethal (1 LD(50)) dose of the highly pathogenic IAV A/Puerto Rico/8/34 (PR8). Our experiments revealed that infection with a 1 LD(50) dose induced peak viral titers at day 2 compared to day 4 in the 0.1 LD(50) dose. Moreover, early cytokine dysregulation was observed in the lethal dose with significantly elevated levels of IFN-α, TNF-α, CXCL9, IL-6, and MCP-1 produced at day 2. Early inflammatory responses following infection with 1 LD(50) correlated with a greater influx of neutrophils into the lung. However, depletion of neutrophils enhanced morbidity following IAV infection. Though no differences in CD8+ cell function were observed, CD4+ effector responses were impaired in the lungs 8 days after infection with 1 LD(50). Histological analysis revealed significant pathology in lethally infected mice at day 2 and day 6 postinfection, when viral titers remained high. Treating lethally infected mice with oseltamivir inhibited viral titers to sublethal levels, and abrogated the pathology associated with the lethal dose. Together, these results suggest that early cytokine dysregulation and viral replication play a role in pulmonary damage and high mortality in lethally infected mice.

Inflammation enhances IL-2 driven differentiation of cytolytic CD4 T cells

Cytolytic CD4 T cells (CD4 CTL) have been identified in vivo in response to viral infections; however, the factors necessary for driving the cytolytic phenotype have not been fully elucidated. Our previously published work suggests IL-2 may be the master regulator of perforin-mediated cytotoxicity in CD4 effectors. To further dissect the role of IL-2 in CD4 CTL generation, T cell receptor transgenic mice deficient in the ability to produce IL-2 or the high affinity IL-2 receptor (IL-2Rα, CD25) were used. Increasing concentrations of IL-2 were necessary to drive perforin (Prf) expression and maximal cytotoxicity. Granzyme B (GrB) expression and killing correlated with STAT5 activation and CD25 expression in vitro, suggesting that signaling through the high affinity IL-2R is critical for full cytotoxicity. IL-2 signaling was also necessary in vivo for inducing the Th1 phenotype and IFN-γ expression in CD4 T cells during influenza A (IAV) infection. In addition, GrB expression, as measured by mean fluorescent intensity, was decreased in CD25 deficient cells; however, the frequency of CD4 cells expressing GrB was unchanged. Similarly, analysis of cytolytic markers such as CD107a/b and Eomesodermin indicate high IL-2Rα expression is not necessary to drive the CD4 CTL phenotype during IAV infection. Thus, inflammatory signals induced by viral infection may overcome the need for strong IL-2 signals in driving cytotoxicity in CD4 cells.

Interferon response factor 3 is crucial to poly-I:C induced NK cell activity and control of B16 melanoma growth

Interferon Response Factor 3 (IRF3) induces several NK-cell activating factors, is activated by poly-I:C, an experimental cancer therapeutic, but is suppressed during many viral infections. IRF3 Knockout (KO) mice exhibited enhanced B16 melanoma growth, impaired intratumoral NK cell infiltration, but not an impaired poly-I:C therapeutic effect due to direct suppression of B16 growth. IRF3 was responsible for poly-I:C decrease in TIM-3 expression by intratumoral dendritic cells, induction of NK-cell Granzyme B and IFN-γ, and induction of macrophage IL-12, IL-15, IL-6, and IRF3-dependent NK-activating molecule (INAM). Thus, IRF3 is a key factor controlling melanoma growth through NK-cell activities, especially during poly-I:C therapy.

IRF3 helps control acute TMEV infection through IL-6 expression but contributes to acute hippocampus damage following TMEV infection

IRF3 is an innate anti-viral factor whose role in limiting Theiler's murine encephalomyelitis virus (TMEV) infection and preventing TMEV-induced disease is unclear. Acute disease and innate immune responses of macrophages were examined in IRF3 knockout mice compared with C57Bl/6 mice following in vitro or intracranial infection with either TMEV GDVII or DA. IRF3 deficiency augmented viral infection, as well as morbidity and mortality following intracranial infection with neurovirulent TMEV GDVII. In contrast, IRF3 deficiency prevented hippocampal injury following intracranial infection with persistent TMEV DA. The extent of TMEV infection in macrophages from C57Bl/6 mice was significantly less than that in IRF3 deficient macrophages, which was associated with poor IFN-β and IL-6 expression in response to TMEV. Reestablishing IRF3 expression in IRF3 deficient macrophages increased control of TMEV replication and increased expression of IFN-β and IL-6. In addition, IRF3 deficient macrophages failed to exhibit IL-6 antiviral effects, which was associated with inability to sustain IL-6-induced STAT1 activation compared with C57BL/6 macrophages. Altogether, IRF3 contributes to early control of TMEV replication through induction of IL-6 and IFN-β and support of IL-6 antiviral effects, but contributes to TMEV-induced hippocampal injury.

Effect of coating with lung lining fluid on the ability of fibres to produce a respiratory burst in rat alveolar macrophages

The aim of the study was to develop a simple short-term in vitro assay which would allow us to predict the pathogenicity of fibres based on data already available from in vivo studies. Fibres were used naked (uncoated) or coated with rat IgG, or rat or sheep surfactant. The fibres were used to stimulate superoxide anion release by rat alveolar macrophages. Binding of fibres to rat alveolar macrophages was assessed by optical microscopy. Fibres used in the naked state produced little or no stimulation of superoxide anion from rat alveolar macrophages. When fibres were coated with rat IgG there was a significant increase in superoxide release for all fibre types with the exception of RCF4 and Code 100/475. When fibres were coated with rat or sheep surfactant, there was suppression of the respiratory burst for all fibre types. The observed suppression was not due to a scavenging effect by the surfactant itself, because xanthine/xanthine oxidase generated superoxide was unaffected by surfactant. The suppressive effect was shown to act directly on the macrophages. Comparing naked and coated fibres for their ability to bind to macrophages, it was shown that in general more coated fibres were bound and that increased binding was associated with suppressed superoxide release for both types of surfactant-coated fibres. It was concluded that the nature of the fibre coating is the main factor influencing the interaction between fibres and macrophages. The type of binding through different receptors may either stimulate or switch off the respiratory burst. The assay used here does not, however, allow any predictions to be made regarding the pathogenicity of fibres.

The role of oxidative stress in the prolonged inhibitory effect of ultrafine carbon black on epithelial cell function

Respired ultrafine particles induce a greater inflammation in rat lungs than fine particles; we have hypothesized that this is due to their comparatively huge number and surface area for the production of free radicals. We tested this hypothesis by studying the effects of fine and ultrafine (uf) carbon black (CB) particles in comparison with quartz on A549 human type II alveolar epithelial cells, particularly with respect to the oxidative properties of these particles. Treatment with fine CB (diameter 260nm), and quartz (up to 0.78mug/mm(2)) for 24 hours significantly (P<0.05) decreased the A549 cells metabolic competence, as measured by the ability to reduce MTT to a formazan product. The inhibitory effects of uf CB only became significantly different (P<0.05) relative to the control at 48 hours, by which time the effects of fine CB and quartz were no longer significant. The inhibition of MTT reduction by uf CB was prevented by the hydroxyl radical scavenger mannitol (2mm). In addition, measurement of reactive oxygen species production using supercoiled plasmid DNA showed that uf CB exhibited significantly more free radical activity than fine CB (P<0.05). In the absence of serum, uf CB depleted reduced glutathione at 6 hours (P<0.008). In contrast, CB did not significantly alter reduced or oxidized glutathione. Hence, compared with fine CB, uf CB exhibited greater free radical activity, greater inhibition of the reduction of MTT at 48 hours (prevented by mannitol) and a depletion of reduced glutathione. These results suggest that uf CB induces a greater oxidative stress than fine CB, and that this may play a role in the toxicological effects of this ultrafine particle.

Memory CD4+ T cells protect against influenza through multiple synergizing mechanisms

Memory CD4+ T cells combat viral infection and contribute to protective immune responses through multiple mechanisms, but how these pathways interact is unclear. We found that several pathways involving memory CD4+ T cells act together to effectively clear influenza A virus (IAV) in otherwise unprimed mice. Memory CD4+ T cell protection was enhanced through synergy with naive B cells or CD8+ T cells and maximized when both were present. However, memory CD4+ T cells protected against lower viral doses independently of other lymphocytes through production of IFN-γ. Moreover, memory CD4+ T cells selected for epitope-specific viral escape mutants via a perforin-dependent pathway. By deconstructing protective immunity mediated by memory CD4+ T cells, we demonstrated that this population simultaneously acts through multiple pathways to provide a high level of protection that ensures eradication of rapidly mutating pathogens such as IAV. This redundancy indicates the need for reductionist approaches for delineating the individual mechanisms of protection mediated by memory CD4+ T cells responding to pathogens.

Coxsackievirus B3 infection leads to the generation of cardiac myosin heavy chain-α-reactive CD4 T cells in A/J mice

Enteroviruses like coxsackievirus B3 (CVB3) are common suspects in myocarditis/dilated cardiomyopathy patients. Autoimmunity has been proposed as an underlying mechanism, but direct evidence of its role is lacking. To delineate autoimmune response in CVB3 myocarditis, we used IA(k) dextramers for cardiac myosin heavy chain (Myhc)-α 334-352. We have demonstrated that myocarditis-susceptible A/J mice infected with CVB3 generate Myhc-α-reactive CD4 T cells and such a repertoire was absent in naïve mice as measured by proliferative response to Myhc-α 334-352 and IA(k) dextramer staining. We also detected Myhc-α 334-352 dextramer(+) cells in the hearts of CVB3-infected mice. The autoreactive T cell repertoire derived from infected mice contained a high frequency of interleukin-17-producing cells capable of inducing myocarditis in naïve recipients. The data suggest that CVB3, a bona fide pathogen of cardiovascular system that primarily infects the heart can lead to the secondary generation of autoreactive T cells and contribute to cardiac pathology.

IRF3 polymorphisms induce different innate anti-Theiler's virus immune responses in RAW264.7 macrophages

Persistent viral infections can lead to disease such as myocarditis. Theiler's murine encephalomyelitis virus (TMEV) infects macrophages of SJL/J (H-2s) mice establishing persistent infections leading to demyelinating disease. In contrast macrophages from B10.S (H-2s) mice clear TMEV. Activation of the transcription factor IRF3 induces IFNβ, ISG56, and apoptosis for viral clearance, but also inflammatory cytokines, such as IL-23 and IL6, which contribute to disease. Here we identify polymorphisms in the IRF3 of SJL/J versus B10.S mice that are located in DNA binding, nuclear localization, and autoinhibitory domains. SJL-IRF3 expression in RAW264.7 macrophage cells with or without TMEV infection decreased IL-23p19 promoter activity compared with B10S-IRF3. In contrast SJL-IRF3 increased IL-6, ISG56 and IFNβ in response to TMEV. B10S-IRF3 expression augmented apoptotic caspase activation and decreased viral RNA in TMEV-infected macrophages while SJL-IRF3 increased viral replication with less caspase activation. Therefore IRF3 polymorphisms contribute to viral persistence and altered cytokine expression.

The Ganglionic Blocking Activity of A Series Of Tertiary Sulphonium Quaternary Ammonium Salts

A number of polymethylene bis-tertiary sulphonium quaternary ammonium salts have been examined for their ganglionic blocking activity on the superior cervical ganglion of the cat. The effect of substituting different alkyl groups on the sulphur and nitrogen atoms and varying the length of the polymethylene chain has been investigated. Maximum activity was found in the tetramethylene di-ethyl sulphonium tri-ethyl ammonium salt, which was about three times as active as hexamethonium. With tri-, penta- and hexamethylene salts maximum activity occurs when there are a total of 13 to 15 carbon atoms in the molecule. It is concluded that the substitution of sulphur for nitrogen in the bis-quaternary ammonium salts does not necessarily lead to a reduction in relative potency. The importance of the groupings on the “onium” centres in producing ganglionic block is stressed.