Computational and Systems Biology Advances to Enable Bioagent Agnostic Signatures

Enumerated threat agent lists have long driven biodefense priorities. The global SARS-CoV-2 pandemic demonstrated the limitations of searching for known threat agents as compared to a more agnostic approach. Recent technological advances are enabling agent-agnostic biodefense, especially through the integration of multi-modal observations of host-pathogen interactions directed by a human immunological model. Although well-developed technical assays exist for many aspects of human-pathogen interaction, the analytic methods and pipelines to combine and holistically interpret the results of such assays are immature and require further investments to exploit new technologies. In this manuscript, we discuss potential immunologically based bioagent-agnostic approaches and the computational tool gaps the community should prioritize filling.

The association of allostasis with alcohol use: A case-control study in males with and without alcohol use disorder

BACKGROUND

Allostatic load (AL) is associated with a heightened predisposition to disease due to prolonged activation of biological stress-response systems. Alcohol use disorder (AUD) is known to activate these systems. The primary aim of the current study was to examine the relationship between AL and AUD.

METHODS

Participants were males (100%) with DSM-IV Alcohol Dependence (n = 48) and healthy participants with no history of substance use disorder (n = 17). Participants with AUD were 4-6 weeks abstinent. The AL index used cortisol, interleukin-6 (IL-6), fibrinogen, tumor necrosis factor-alpha (TNFα), C-reactive protein (CRP), glucose, insulin, leptin, pulse, systolic blood pressure readings, diastolic blood pressure readings, and body mass index (BMI). Physiological dysregulation for each biological measure was determined based on values within the 25th or 75th percentiles; AL was calculated as the total number of physiologically dysregulated biological measures.

RESULTS

No differences in mean AL scores between the cases and controls [t(63) = .48, p = .633] were observed. Among cases, AL was not associated with lifetime drinks per drinking day (F(2,42) = .42, p = .662), lifetime total drinks (F(2,42) = 0.48, p = .620), total drinks 6 months prior to participating in the study (F(2,43) = 0.58, p = .563), or drinks per drinking day at 3-month follow-up (F(2,35) = 1.93, p = .161). AL was negatively associated with drinks per drinking day 6 months prior to study participation (F(2,42) = 3.71, p = .033).

CONCLUSIONS

The hypotheses were not supported. Given that alcohol is likely to lead to physiological dysregulation, the apparent absence of a relationship between biomarkers of cumulative stress as indicated by AL and drinking status was both unanticipated and remarkable. Based on the results, AL in the context of drinking status or drinking among males with AUD may not be applicable.

Alcohol self-administration and nicotine withdrawal alter biomarkers of stress and inflammation and prefrontal cortex changes in Gβ subunits

Background: Although alcohol and nicotine are often used together, the biological consequences of these substances are not well understood. Identifying shared targets will inform cessation pharmacotherapies and provide a deeper understanding of how co-use of alcohol and nicotine impacts health, including biomarkers of stress and inflammation.Objective: We examined the effects of nicotine exposure and withdrawal on alcohol self-administration (SA), stress and inflammatory biomarkers, and a G-protein coupled receptor subunit (Gβ) in brain areas associated with drug use.Methods: Male rats were trained to SA alcohol and then received a nicotine pump (n = 7-8 per group). We assessed alcohol intake for 12 days during nicotine exposure and then following pump removal to elicit withdrawal. After the behavioral studies, we assessed plasma leptin, corticosterone, and interleukin-1β (IL-1β), and Gβ protein expression in the amygdala, nucleus accumbens (NAc), and prefrontal cortex (PFC).Results: Nicotine exposure or withdrawal did not alter alcohol intake (p > .05). Alcohol and nicotine withdrawal elevated corticosterone levels (p = .015) and decreased Gβ levels in the PFC (p = .004). In the absence of nicotine, alcohol SA suppressed IL-1β levels (p = .039). Chronic exposure to nicotine or withdrawal during alcohol SA did not alter leptin levels or Gβ expression in the amygdala or NAc (p's > .05).Conclusions: The combination of alcohol SA and nicotine withdrawal produced a persistent increase in stress biomarkers and a suppression in Gβ expression in the PFC, providing an important first step toward understanding the common biological mechanisms of alcohol/nicotine misuse.

Identifying innate immune receptors causing production of inflammatory cytokines by infection of Francisella tularensis

Francisella tularensis is a pathogenic species and a causative agent of tularemia. This bacterium is incredibly infectious and often lethal in that F. tularensis induces the overproduction of pro-inflammatory cytokines. This study aims to identify the innate immune receptors responsible for the production of inflammatory cytokines in response to F. tularensis infection. The study uses an immortalized C57BL/6 Bone Marrow Macrophage (BMMac) cell line as the control and knockout BMMac deficient in various innate immune receptors. The cells are passaged and seeded before infecting them with F. tularensis for 2 hours. The cells were treated with a high dose of gentamicin for 2 hours, followed by a low dose of gentamicin for an incubation period of 24 hours. The supernatant from these cells is then collected and analysis processed by ELISA, an enzyme-linked immunosorbent assay, to measure the production of inflammatory cytokines. The results were compared with the positive control of wild-type BMMac and the negative control of uninfected BMMac cells. Analysis of these mutants reveals the involvement of innate immune receptors in triggering the pro-inflammatory cytokine storm in response to F. tularensis infection that leads to the host’s death.

Supported by NIH (SC1 GM122699-01A1)

Increased M1 macrophage activity makes females more sensitive to Francisella tularensis infection

The intensity of the inflammatory response differs between males and females, with females having a stronger basal inflammatory response compared with males. This leads to differences in sensitivity to autoimmune and infectious diseases. Males tend to be more susceptible to infectious diseases whereas females tend to be more susceptible to autoimmune diseases. However, certain infectious diseases cause disease by over stimulating an inflammatory response resulting in dysregulation of cytokine production and generation of a cytokine storm. We hypothesized that the elevated basal inflammatory state of females would make them more susceptible to inflammatory infectious diseases such as Francisella tularensis. Indeed, survival and immunological studies demonstrated that females had a stronger innate immune response and were more likely to succumb to tularemic-disease compared with males. Importantly, this dichotomy was independent of hormonal signaling. We traced the source of this elevated inflammatory response to alterations in the M1 and M2 macrophage activation profile. In females, M1 macrophages were activated earlier than in males in response to inoculation. These M1 macrophages from female mice showed a stronger activation both in vivo and in vitro cultures. This was consistent in both mouse and human systems. Our results demonstrate that females possess a higher abundance of M1 macrophages and that these M1 macrophages are more inflammatory in response to F. tularensis infection. This suggests that the consequence of the dichotomy between the male and female inflammatory response is dependent upon the mechanism of disease triggered by infectious diseases.

Supported by grants from the NIH (SC1 GM122699-01A1) and NSF (MRI 1626587).

Neural Dysfunction Following Francisella tularensis Infection

Francisella tularensis is a gram-negative intracellular coccobacillus that is the causative agent of tularemia. Local, acute inflammation is beneficial since it can clear bacterial infections, remove cellular damage and promote the healing of tissue. However, F. tularensis is capable of bypassing the immune system and causing an over-activation of inflammation, known as a “cytokine storm”. This cytokine storm increases host cell damage, nutrient availability and serves an immune distraction allowing the bacterium to replicate. Other infections that cause cytokine storms include Ebola, pandemic influenza, hantavirus, and HIV, all BSL3 pathogens.

The routes of transmission for F. tularensis are many and intertwined. Infection could be the result of inhaling air droplets containing infectious bacteria, coming into direct contact with an infected animal or being bitten by an infected arthropod such as a tick, flea or mosquito. Eating and drinking contaminated meat and water can also lead to infection and different disease manifestations occur depending on the route of transmission.

While extensive research has documented infection of the spleen, liver and lung, there hasn’t been any reports of F. tularensis productively infecting the brain, until now. This work focuses on characterizing the effects of F. tularensis infection of the brain. We hypothesize that damage caused by F. tularensis neural infection will have a negative effect on behavior. This work aims to identify these negative effects based on the anatomical location of the bacteria foci, regions containing numerous bacteria. With the use of brain mapping and behavioral assays, we seek to determine the impact of F. tularensis infection on behavior and cognition.

Alginate Hydrogels with Embedded ZnO Nanoparticles for Wound Healing Therapy

INTRODUCTION

In this in-vitro study, we designed a 3D printed composite of zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activities encapsulated within hydrogel (alginate) constructs, for antibacterial purposes applicable towards wound healing. We primarily sought to confirm the mechanical properties and cell compatibility of these ZnO NP infused scaffolds.

METHODS

The antibacterial property of the ZnO NPs was confirmed by hydroxyl radical generation using ultraviolet (U.V.) photocatalysis. Titanium dioxide (TiO2), a well-known antibacterial compound, was used as a positive control (1% w/v) for the ZnO NP-based alginate constructs and their antibacterial efficacies compared. Among the ZnO group, 3D printed gels containing 0.5% and 1% w/v of ZnO were analyzed and compared with manually casted samples via SEM, swelling evaluation, and rheological analysis. Envisioning an in-vivo application for the 3D printed ZnO NP-based alginates, we studied their antibacterial properties by bacterial broth testing, cytocompatibility via live/dead assay, and moisture retention capabilities utilizing a humidity sensor.

RESULTS

3D printed constructs revealed significantly greater pore sizes and enhanced structural stability compared to manually casted samples. For all samples, the addition of ZnO or TiO2 resulted in significantly stiffer gels in comparison with the alginate control. Bacterial resistance testing on Staphylococcus epidermidis indicated the addition of ZnO NPs to the gels decreased bacterial growth when compared to the alginate only gels. Cell viability of STO-fibroblasts was not adversely affected by the addition of ZnO NPs to the alginate gels. Furthermore, the addition of increasing doses of ZnO NPs to the alginate demonstrated increased humidity retention in gels.

DISCUSSION

The customization of 3D printed alginates containing antibacterial ZnO NPs leads to an alternative that allows accessible mobility of molecular exchange required for improving chronic wound healing. This scaffold can provide a cost-effective and durable antibacterial treatment option.

Differences in the M1 and M2 macrophage subtypes between the sexes determine susceptibility to Francisella tularensis infection

Francisella tularensis is the causative agent of the human disease tularemia. F. tularensis infects a variety of cells, including macrophages, in order to cause pathogenicity. As few as 10 inhaled microorganisms cause a lethal infection by over-activating the host’s own inflammatory response. Differences in the intensity of the inflammatory response exist between the sexes which leads to differences in sensitivity to autoimmune and infectious disease. Males tend to be more susceptible to infectious diseases whereas females tend to be more susceptible to autoimmune diseases. However, our preliminary data unexpectedly demonstrated that female mice were more susceptible to F. tularensis--mediated disease than male mice. We hypothesized that female macrophages respond to F. tularensis infection by generating a more intense inflammatory response which makes females more susceptible to F. tularensis. Indeed, female mice infected with F. tularensis generate significantly more inflammatory M1 macrophages compared to male mice. Furthermore, naïve M1 and M2 macrophages were infected in vitro to directly compare cellular responses between male and female mice. On a per cell basis, M1 macrophages from female mice generated a more robust inflammatory response compared with M1 macrophages from male mice. This suggests that M1 macrophages from females respond more strongly to infection resulting in the heightened inflammatory response.

Identifying innate immune receptors causing production of inflammatory cytokines by infection of Francisella tularensis

Francisella tularensis is a pathogenic species and a causative agent of tularemia. This bacterium is incredibly infectious and often lethal in that F. tularensis causes the overproduction of pro-inflammatory cytokines. The objective of this study is to identify the innate immune receptors responsible for the production of inflammatory cytokines in response to F. tularensis infection. The study uses an immortalized C57BL/6 Bone Marrow Macrophage (BMMac) cell line as the control and knockout BMMac that are deficient in various innate immune receptors. The cells are passaged and seeded before infecting them with F. tularensis for 2 hours. The cells are treated with a high dose of gentamicin for 2 hours followed by a low dose of gentamicin for an incubation period of 24 hours. The supernatant from these cells are then collected and analysis processed by ELISA, an enzyme-linked immunosorbent assay, to measure production of inflammatory cytokines. These data were compared with the positive control of wild type BMMac and the negative control of uninfected BMMac cells. Analysis of these mutants reveal the involvement of innate immune receptors in triggering the pro-inflammatory cytokine storm in response to F. tularensis infection that leads to death of the host.

Neural Dysfunction Following Francisella tularensis Infection

Francisella tularensis is a gram-negative intracellular coccobacillus that is the causative agent of tularemia. Local, acute inflammation is beneficial since it can clear bacterial infections, remove cellular damage and promote the healing of tissue. However, F. tularensis is capable of bypassing the immune system and causing an overactivation of inflammation, known as a “cytokine storm”. This cytokine storm increases host cell damage, nutrient availability and serves an immune distraction allowing the bacterium to replicate. Other infections that cause cytokine storms include ebola, pandemic influenza, hantavirus, and HIV, all BSL3 pathogens.

The routes of transmission for F. tularensis are many and intertwined. Infection could be the result of inhaling air droplets containing infectious bacteria, coming into direct contact with an infected animal or being bitten by an infected arthropod such as a tick, flea or mosquito. Eating and drinking contaminated meat and water can also lead to infection and different disease manifestations occur depending on the route of transmission.

While extensive research has documented infection of the spleen, liver and lung, there hasn’t been any reports of F. tularensis productively infecting the brain, until now. This work focuses on characterizing the effects of F. tularensis infection of the brain. We hypothesize that damage caused by F. tularensis neural infection will have a negative effect on behavior. This work aims to identify these negative effects based on the anatomical location of the bacteria foci, regions containing numerous bacteria. With the use of brain mapping and behavioral assays, we seek to determine the impact of F. tularensis infection on behavior and cognition.

A novel neuroinvasive infection modality for Francisella tularensis elicits neuroinflammation resulting in cellular damage

Francisella tularensis (Ft.) is a gram-negative coccobacillus bacterium that causes the zoonotic disease tularemia in humans. Ft. causes the most severe form of the disease through inhalation, but is most commonly transmitted through direct contact with infected animal carcasses such as rodents and rabbits. Due to its extremely low infectious dose, high mortality rate, and potential use as a biological warfare agent, Ft. is classified by the CDC as a Tier 1 select agent. Ft. infection triggers an overactive inflammatory response, termed a “cytokine storm”, which produces excessive tissue damage of vital organs, leading to rapid death of the host before its adaptive immunity responses can be brought to bear against the infection. In the periphery, macrophages, paradoxically the target cell for Ft., provide innate immune defense against foreign material, including bacteria. Microglia, the resident macrophage-like cells of the central nervous system, rapidly respond to pathological changes, serving a similar function as macrophages. Their rapid activation is an important factor in guarding the neural parenchyma against infectious diseases, inflammation, and neurodegeneration while maintaining and facilitating the return to tissue homeostasis. In the United States, several clinical cases of tularemic meningitis were diagnosed since 1931; however, there is no further research exploring the condition. We hypothesize that, after peripheral inoculation of Ft., the bacteria infiltrate the central nervous system using a Trojan horse-type mechanism and infect microglia, leading to overproduction of pro-inflammatory cytokines in the brain which then cause damage to surrounding neurons, ultimately leading to death.

Suppression of Inflammation of the Cytokine Storm Following Francisella Tularensis Infection is Mediated by Natural Killer T Cell Subsets

Francisella tularensis is intracellular bacteria which is the causative agent of the disease tularemia. Highly virulent in both humans and animals, it takes only as few as ten microorganisms to cause a lethal infection. The bacteria can enter via direct or indirect routes causing the activations of the host innate inflammatory response to ensue. The function of the bacteria once its entered the host cell is to be opsonized by phagocytic cell, survive and continue to proliferate in the host causing pathogenicity.

The bacteria invade host dendritic cells, neutrophils, and predominately macrophages. This causes a mass inflammatory response resulting in the cytokine storm. Activation of natural killer T cells has been shown to suppress inflammation in in vitro functional assay studies. We know that select populations of NKT cells influence the cytokine storm at the onset of infection. Our hypothesis seeks to determine whether type one versus type two natural killer T cells are inhibiting inflammation. Based on our preliminary results we hypothesize that the type one NKT cells will show cell suppression.

Insulin modulates the strong reinforcing effects of nicotine and changes in insulin biomarkers in a rodent model of diabetes

This study examined whether the strong reinforcing effects of nicotine and changes in insulin biomarkers observed in diabetic rats are modulated via insulin. A model of diabetes was employed involving administration of streptozotocin (STZ), which produces hypoinsulinemia in rats. The present study included vehicle- or STZ-treated rats that received sham surgery or insulin pellets. Two weeks later, the rats were given extended access to intravenous self-administration (IVSA) of saline or nicotine. Concomitant changes in food intake, water responses, and body weight were assessed during 12 days of IVSA. After the last session, plasma levels of insulin, leptin, amylin, and glucagon-like peptide-1 (GLP-1) were assessed using Luminex^® technology. In a separate cohort, phosphorylated insulin receptor substrate-2 (pIRS-2) and insulin growth factor-1 receptor β (IGF-1Rβ) were assessed in the nucleus accumbens (NAc) and ventral tegmental area (VTA) of vehicle- or STZ-treated rats that received sham surgery or an insulin pellet. STZ-treated rats displayed an increase in glucose levels, a decrease in body weight, and an increase in nicotine, food, and water intake relative to controls. STZ-treated rats also displayed a decrease in plasma insulin and leptin levels and an increase in amylin and GLP-1 levels relative to controls. Importantly, all of the STZ-induced changes in behavior and insulin biomarkers were prevented by insulin supplementation. STZ-treated rats also displayed a decrease in pIRS-2 and IGF-1Rβ in the NAc (but not VTA), an effect that was also prevented by insulin. These data suggest that insulin systems in the NAc modulate the strong reinforcing effects of nicotine in male diabetic rats.

Obesity Exacerbates the Cytokine Storm Elicited by Francisella tularensis Infection of Females and Is Associated with Increased Mortality

Infection with Francisella tularensis, the causative agent of the human disease tularemia, results in the overproduction of inflammatory cytokines, termed the cytokine storm. Excess metabolic byproducts of obesity accumulate in obese individuals and activate the same inflammatory signaling pathways as F. tularensis infection. In addition, elevated levels of leptin in obese individuals also increase inflammation. Since leptin is produced by adipocytes, we hypothesized that increased fat of obese females may make them more susceptible to F. tularensis infection compared with lean individuals. Lean and obese female mice were infected with F. tularensis and the immunopathology and susceptibility monitored. Plasma and tissue cytokines were analyzed by multiplex ELISA and real-time RT-PCR, respectively. Obese mice were more sensitive to infection, developing a more intense cytokine storm, which was associated with increased death of obese mice compared with lean mice. This enhanced inflammatory response correlated with in vitro bacteria-infected macrophage cultures where addition of leptin led to increased production of inflammatory cytokines. We conclude that increased basal leptin expression in obese individuals causes a persistent low-level inflammatory response making them more susceptible to F. tularensis infection and heightening the generation of the immunopathological cytokine storm.

Peripheral Francisella Tularensis Infection Results In Neural Invasion and Pathologic Inflammation

Francisella tularensis infection triggers an overactive inflammatory response by stimulating production of host pro-inflammatory cytokines. Human tularemia, caused by F. tularensis, is a zoonotic disease transmitted by aerosol particles, direct contact, and via arthropod vectors, particularly ticks. With the known peripheral invasion of F. tularensis, and previously published clinical data indicating the presence of our bacterium in cerebral spinal fluid, many questions arise, which include the questions as to which specific neuronal cells are infected. In the periphery, macrophages provide innate immune defense against foreign material, including bacteria. Microglial cells are resident macrophages of the brain and spinal cord and previously have been reported to rapidly respond to pathological changes in the central nervous system, serving a similar function as macrophages. Their rapid activation is an important factor in guarding the neural parenchyma against infectious diseases, inflammation, and neurodegeneration while maintaining and facilitating the return to tissue homeostasis. Therefore, we hypothesized that, having invaded the brain by an unknown mechanism, F. tularensis may be capable of eliciting an immune response following infection of microglial cells. Since macrophage infection leads to elicitation of inflammation, infection of microglia similarly stimulate inflammation leading to neural pathology. Mice were inoculated on the rear flank with fluorescently labeled bacteria. Using fluorescent confocal microscopy, labeled F. tularensis was localized in the brains of infected mice. We analyzed brain homogenates for production of inflammatory cytokines at these sites through Milliplex and qPCR.

Peripheral Francisella Tularensis Infection Results In Neural Invasion and Pathologic Inflammation

Francisella tularensis infection triggers an overactive inflammatory response by stimulating production of host pro-inflammatory cytokines. Human tularemia, caused by F. tularensis, is a zoonotic disease transmitted by aerosol particles, direct contact, and via arthropod vectors, particularly ticks. With the known peripheral invasion of F. tularensis, and previously published clinical data indicating the presence of our bacterium in cerebral spinal fluid, many questions arise, which include the questions as to which specific neuronal cells are infected. In the periphery, macrophages provide innate immune defense against foreign material, including bacteria. Microglial cells are resident macrophages of the brain and spinal cord and previously have been reported to rapidly respond to pathological changes in the central nervous system, serving a similar function as macrophages. Their rapid activation is an important factor in guarding the neural parenchyma against infectious diseases, inflammation, and neurodegeneration while maintaining and facilitating the return to tissue homeostasis. Therefore, we hypothesized that, having invaded the brain by an unknown mechanism, F. tularensis may be capable of eliciting an immune response following infection of microglial cells. Since macrophage infection leads to elicitation of inflammation, infection of microglia similarly stimulate inflammation leading to neural pathology. Mice were inoculated on the rear flank with fluorescently labeled bacteria. Using fluorescent confocal microscopy, labeled F. tularensis was localized in the brains of infected mice. We analyzed brain homogenates for production of inflammatory cytokines at these sites through Milliplex and qPCR.

Viral infection causes a shift in the self peptide repertoire presented by human MHC class I molecules

PURPOSE

MHC class I presentation of peptides allows T cells to survey the cytoplasmic protein milieu of host cells. During infection, presentation of self peptides is, in part, replaced by presentation of microbial peptides. However, little is known about the self peptides presented during infection, despite the fact that microbial infections alter host cell gene expression patterns and protein metabolism.

EXPERIMENTAL DESIGN

The self peptide repertoire presented by HLA-A*01;01, HLA-A*02;01, HLA-B*07;02, HLA-B*35;01, and HLA-B*45;01 (where HLA is human leukocyte antigen) was determined by tandem MS before and after vaccinia virus infection.

RESULTS

We observed a profound alteration in the self peptide repertoire with hundreds of self peptides uniquely presented after infection for which we have coined the term "self peptidome shift." The fraction of novel self peptides presented following infection varied for different HLA class I molecules. A large part (approximately 40%) of the self peptidome shift arose from peptides derived from type I interferon-inducible genes, consistent with cellular responses to viral infection. Interestingly, approximately 12% of self peptides presented after infection showed allelic variation when searched against approximately 300 human genomes.

CONCLUSION AND CLINICAL RELEVANCE

Self peptidome shift in a clinical transplant setting could result in alloreactivity by presenting new self peptides in the context of infection-induced inflammation.

Personalized Proteomics: The Future of Precision Medicine

Medical diagnostics and treatment has advanced from a one size fits all science to treatment of the patient as a unique individual. Currently, this is limited solely to genetic analysis. However, epigenetic, transcriptional, proteomic, posttranslational modifications, metabolic, and environmental factors influence a patient’s response to disease and treatment. As more analytical and diagnostic techniques are incorporated into medical practice, the personalized medicine initiative transitions to precision medicine giving a holistic view of the patient’s condition. The high accuracy and sensitivity of mass spectrometric analysis of proteomes is well suited for the incorporation of proteomics into precision medicine. This review begins with an overview of the advance to precision medicine and the current state of the art in technology and instrumentation for mass spectrometry analysis. Thereafter, it focuses on the benefits and potential uses for personalized proteomic analysis in the diagnostic and treatment of individual patients. In conclusion, it calls for a synthesis between basic science and clinical researchers with practicing clinicians to design proteomic studies to generate meaningful and applicable translational medicine. As clinical proteomics is just beginning to come out of its infancy, this overview is provided for the new initiate.

Deficiencies in myeloid cell populations lead to increased sensitivity of females compared with males to Francisella tularensis infection

Preliminary data demonstrated that a greater percentage of female mice infected with F. tularensis succumbed to disease and developed symptoms faster than male mice. Increases in the serum inflammatory cytokine levels corresponded to this enhanced sensitivity in females consistent with a stronger inflammatory. Herein, we sought to understand the cellular basis for this sex difference in the inflammatory response between males and females. We used a combination of in vivo and ex vivo cellular analysis to determine differences in the cellular response to F. tularensis. Multiparametric cytokine analysis was used to quantify changes in serum and supernatant cytokines, real-time RT-PCR was used to measure cytokine mRNA expression in tissues, and multiparametric flow cytometry was used to discriminate cell populations responsive to infection. Despite a tendency for fewer T regulatory (Treg) cells, males had fewer inflammatory macrophage and an increase in regulatory macrophages. This corresponded with an overall decrease in the transcripts of IL-10, IL-5, and IL-4 in the tissues of mice succumbing to disease and an increase in IL-6 transcripts, a marker for the level of inflammation. The functional deficiency of regulatory macrophages and increase of M1 macrophages may enhance the inflammatory response to F. tularensis ultimately leading to decreased survival. Further investigations will focus on understanding the interactions between these myeloid populations with F. tularensis and other cells of the immune system. Development of therapeutics that activate or induce expansion of regulatory macrophages or that suppress the activity/activation of M1 macrophages may prevent death from this disease.

NKT Cell-Mediated Inhibition of Inflammation

Francisella tularensis is an emerging pathogen stimulating an overactive pro-inflammatory response from the immune system leading to death of the host. Serum cytokine analysis of infected mice shows high pro-inflammatory cytokine production consistent with the overactive immune response in response to F. tularensis infection that correlates with death. Therefore, we sought to control this overwhelming inflammation using F. tularensis as the model trigger. Natural Killer T (NKT) cells are a subset of white blood cells with both pro-inflammatory and regulatory functions that could potentially control this lethal response. Therefore, mice sufficient and deficient in NKT cells were infected with F. tularensis and their survival and cytokine response was compared. Mice lacking NKT cells were more sensitive to the infection and produced higher cytokine levels than mice having NKT cells. These data suggest a regulatory role for NKT cells in controlling the F. tularensis--elicited inflammatory responses. In vitro studies of the effector mechanism controlling this tempering of inflammation suggest the engagement of a surface expressed effector molecule. Ultimately, these investigations will lead to a better understanding of the role of NKT cells in this and other pro-inflammatory infections.

Peripheral Francisella tularensis infection results in neural invasion and pathologic inflammation

Francisella tularensis infection triggers an overactive inflammatory response by stimulating production of host pro-inflammatory cytokines. Human tularemia, caused by F. tularensis, is a zoonotic disease transmitted by aerosol particles, direct contact, and via arthropod vectors, particularly ticks. Curiously, during peripheral inoculation in a mouse model of tularemia, F. tularensis was unexpectedly found in brain homogenates, though there is no prior evidence suggesting neural tropism. In the periphery, macrophages provide innate immune defense against foreign material, including bacteria. Microglial cells are resident macrophages of the brain and spinal cord and previously have been reported to rapidly respond to pathological changes in the central nervous system, serving a similar function as macrophages. Their rapid activation is an important factor in guarding the neural parenchyma against infectious diseases, inflammation, and neurodegeneration while maintaining and facilitating the return to tissue homeostasis. Therefore, we hypothesized that, having invaded the brain by an unknown mechanism, F. tularensis may be capable of eliciting an immune response following infection of microglial cells. Since macrophage infection leads to elicitation of inflammation, infection of microglia similarly stimulate inflammation leading to neural pathology. Mice were inoculated on the rear flank with fluorescently labeled bacteria. Using fluorescent confocal microscopy, labeled F. tularensis was localized in the brains of infected mice. We analyzed brain homogenates for production of inflammatory cytokines at these sites through Milliplex and qPCR.

Discovering naturally processed antigenic determinants that confer protective T cell immunity

CD8+ T cells (TCD8) confer protective immunity against many infectious diseases, suggesting that microbial TCD8 determinants are promising vaccine targets. Nevertheless, current T cell antigen identification approaches do not discern which epitopes drive protective immunity during active infection - information that is critical for the rational design of TCD8-targeted vaccines. We employed a proteomics-based approach for large-scale discovery of naturally processed determinants derived from a complex pathogen, vaccinia virus (VACV), that are presented by the most frequent representatives of four major HLA class I supertypes. Immunologic characterization revealed that many previously unidentified VACV determinants were recognized by smallpox-vaccinated human peripheral blood cells in a variegated manner. Many such determinants were recognized by HLA class I-transgenic mouse immune TCD8 too and elicited protective TCD8 immunity against lethal intranasal VACV infection. Notably, efficient processing and stable presentation of immune determinants as well as the availability of naive TCD8 precursors were sufficient to drive a multifunctional, protective TCD8 response. Our approach uses fundamental insights into T cell epitope processing and presentation to define targets of protective TCD8 immunity within human pathogens that have complex proteomes, suggesting that this approach has general applicability in vaccine sciences.

Sculpting MHC class II-restricted self and non-self peptidome by the class I Ag-processing machinery and its impact on Th-cell responses

It is generally assumed that the MHC class I antigen (Ag)-processing (CAP) machinery - which supplies peptides for presentation by class I molecules - plays no role in class II-restricted presentation of cytoplasmic Ags. In striking contrast to this assumption, we previously reported that proteasome inhibition, TAP deficiency or ERAAP deficiency led to dramatically altered T helper (Th)-cell responses to allograft (HY) and microbial (Listeria monocytogenes) Ags. Herein, we tested whether altered Ag processing and presentation, altered CD4(+) T-cell repertoire, or both underlay the above finding. We found that TAP deficiency and ERAAP deficiency dramatically altered the quality of class II-associated self peptides suggesting that the CAP machinery impacts class II-restricted Ag processing and presentation. Consistent with altered self peptidomes, the CD4(+) T-cell receptor repertoire of mice deficient in the CAP machinery substantially differed from that of WT animals resulting in altered CD4(+) T-cell Ag recognition patterns. These data suggest that TAP and ERAAP sculpt the class II-restricted peptidome, impacting the CD4(+) T-cell repertoire, and ultimately altering Th-cell responses. Together with our previous findings, these data suggest multiple CAP machinery components sequester or degrade MHC class II-restricted epitopes that would otherwise be capable of eliciting functional Th-cell responses.

Granzyme A produced by γ(9)δ(2) T cells induces human macrophages to inhibit growth of an intracellular pathogen

Human γ₉δ₂ T cells potently inhibit pathogenic microbes, including intracellular mycobacteria, but the key inhibitory mechanism(s) involved have not been identified. We report a novel mechanism involving the inhibition of intracellular mycobacteria by soluble granzyme A. γ₉δ₂ T cells produced soluble factors that could pass through 0.45 µm membranes and inhibit intracellular mycobacteria in human monocytes cultured below transwell inserts. Neutralization of TNF-α in co-cultures of infected monocytes and γ₉δ₂ T cells prevented inhibition, suggesting that TNF-α was the critical inhibitory factor produced by γ₉δ₂ T cells. However, only siRNA- mediated knockdown of TNF-α in infected monocytes, but not in γ₉δ₂ T cells, prevented mycobacterial growth inhibition. Investigations of other soluble factors produced by γ₉δ₂ T cells identified a highly significant correlation between the levels of granzyme A produced and intracellular mycobacterial growth inhibition. Furthermore, purified granzyme A alone induced inhibition of intracellular mycobacteria, while knockdown of granzyme A in γ₉δ₂ T cell clones blocked their inhibitory effects. The inhibitory mechanism was independent of autophagy, apoptosis, nitric oxide production, type I interferons, Fas/FasL and perforin. These results demonstrate a novel microbial defense mechanism involving granzyme A-mediated triggering of TNF-α production by monocytes leading to intracellular mycobacterial growth suppression. This pathway may provide a protective mechanism relevant for the development of new vaccines and/or immunotherapies for macrophage-resident chronic microbial infections.

A small subset of human T cells express γ₉δ₂ T cell receptors and recognize unique non-peptide phosphoantigens expressed by microbes and damaged cells, such as cancer. These cells are important because: 1) they reside within skin and mucosal surfaces at critical points of initial pathogen invasion, and 2) they are not restricted by polymorphic HLA types and thus can be activated by the same cognate antigens in highly diverse populations. Many important human pathogens such as the causes of AIDS, malaria, tuberculosis and others induce potent responses in γ₉δ₂ T cells that can be protective. However, the key mechanisms involved in γ₉δ₂ T cell-mediated protective immunity are not well defined. We have found that γ₉δ₂ T cells produce soluble granzyme A which correlates with their ability to protect against intracellular mycobacterial growth. We show directly that highly purified granzyme A alone can trigger human monocytes to control intracellular mycobacteria. We further show that the granzyme A-induced mycobacterial inhibition required production of TNF-α by infected monocytes. These studies may have important implications for future vaccine development and novel therapeutic strategies.

IL-15 regulates homeostasis and terminal maturation of NKT cells

Semi-invariant NKT cells are thymus-derived innate-like lymphocytes that modulate microbial and tumor immunity as well as autoimmune diseases. These immunoregulatory properties of NKT cells are acquired during their development. Much has been learned regarding the molecular and cellular cues that promote NKT cell development, yet how these cells are maintained in the thymus and the periphery and how they acquire functional competence are incompletely understood. We found that IL-15 induced several Bcl-2 family survival factors in thymic and splenic NKT cells in vitro. Yet, IL-15-mediated thymic and peripheral NKT cell survival critically depended on Bcl-x(L) expression. Additionally, IL-15 regulated thymic developmental stage 2 to stage 3 lineage progression and terminal NKT cell differentiation. Global gene expression analyses and validation revealed that IL-15 regulated Tbx21 (T-bet) expression in thymic NKT cells. The loss of IL-15 also resulted in poor expression of key effector molecules such as IFN-γ, granzyme A and C, as well as several NK cell receptors, which are also regulated by T-bet in NKT cells. Taken together, our findings reveal a critical role for IL-15 in NKT cell survival, which is mediated by Bcl-x(L), and effector differentiation, which is consistent with a role of T-bet in regulating terminal maturation.

Live and inactivated influenza vaccines induce similar humoral responses, but only live vaccines induce diverse T-cell responses in young children

BACKGROUND

Two doses of either trivalent live attenuated or inactivated influenza vaccines (LAIV and TIV, respectively) are approved for young children (≥ 24 months old for LAIV and ≥ 6 months old for TIV) and induce protective antibody responses. However, whether combinations of LAIV and TIV are safe and equally immunogenic is unknown. Furthermore, LAIV is more protective than TIV in children for unclear reasons.

METHODS

Children 6-35 months old were administered, 1 month apart, 2 doses of either TIV or LAIV, or combinations of LAIV and TIV in both prime/boost sequences. Influenza-specific antibodies were measured by hemagglutination inhibition (HAI), and T cells were studied in flow cytometric and functional assays. Highly conserved M1, M2, and NP peptides predicted to be presented by common HLA class I and II were used to stimulate interferon-γ enzyme-linked immunospot responses.

RESULTS

All LAIV and/or TIV combinations were well tolerated and induced similar HAI responses. In contrast, only regimens containing LAIV induced influenza-specific CD4(+), CD8(+), and γδ T cells, including T cells specific for highly conserved influenza peptides.

CONCLUSIONS

Prime/boost combinations of LAIV and TIV in young children were safe and induced similar protective antibodies. Only LAIV induced CD4(+), CD8(+), and γδ T cells relevant for broadly protective heterosubtypic immunity.

CLINICAL TRIALS REGISTRATION

NCT00231907.

Only a subset of phosphoantigen-responsive gamma9delta2 T cells mediate protective tuberculosis immunity

Mycobacterium tuberculosis and Mycobacterium bovis bacillus Calmette-Guérin (BCG) induce potent expansions of human memory Vgamma(9)(+)Vdelta(2)(+) T cells capable of IFN-gamma production, cytolytic activity, and mycobacterial growth inhibition. Certain phosphoantigens expressed by mycobacteria can stimulate gamma(9)delta(2) T cell expansions, suggesting that purified or synthetic forms of these phosphoantigens may be useful alone or as components of new vaccines or immunotherapeutics. However, we show that while mycobacteria-activated gamma(9)delta(2) T cells potently inhibit intracellular mycobacterial growth, phosphoantigen-activated gamma(9)delta(2) T cells fail to inhibit mycobacteria, although both develop similar effector cytokine and cytolytic functional capacities. gamma(9)delta(2) T cells receiving TLR-mediated costimulation during phosphoantigen activation also failed to inhibit mycobacterial growth. We hypothesized that mycobacteria express Ags, other than the previously identified phosphoantigens, that induce protective subsets of gamma(9)delta(2) T cells. Testing this hypothesis, we compared the TCR sequence diversity of gamma(9)delta(2) T cells expanded with BCG-infected vs phosphoantigen-treated dendritic cells. BCG-stimulated gamma(9)delta(2) T cells displayed a more restricted TCR diversity than phosphoantigen-activated gamma(9)delta(2) T cells. In addition, only a subset of phosphoantigen-activated gamma(9)delta(2) T cells functionally responded to mycobacteria-infected dendritic cells. Furthermore, differential inhibitory functions of BCG- and phosphoantigen-activated gamma(9)delta(2) T cells were confirmed at the clonal level and were not due to differences in TCR avidity. Our results demonstrate that BCG infection can activate and expand protective subsets of phosphoantigen-responsive gamma(9)delta(2) T cells, and provide the first indication that gamma(9)delta(2) T cells can develop pathogen specificity similar to alphabeta T cells. Specific targeting of protective gamma(9)delta(2) T cell subsets will be important for future tuberculosis vaccines.

Mycobacteria Induce Protective Effector Functions in a Subset of Nonprotective Phosphoantigen-reactive γ9δ2 T cells (43.21)

Human γ9δ2 T cells expand and produce protective cytokine and cytolytic responses during mycobacterial infection. γ9δ2 T cells are also stimulated by nonpeptidic phosphoantigens (i.e-IPP, HMB-PP), expressed by intracellular mycobacteria and infected cells. Therefore, purified phosphoantigens could be useful components of new vaccines or immunotherapeutics by stimulating protective γ9δ2 T cells. However, it is unclear whether γ9δ2 T cells induced by phosphoantigens can protect against mycobacterial replication. We show that while BCG-expanded γ9δ2 T cells potently inhibit intracellular mycobacterial growth, IPP/HMB-PP-expanded γ9δ2 T cells fail to inhibit intracellular mycobacteria, although both lyse Daudi targets. TLR co-stimulation during IPP expansion also failed to induce anti-mycobacterial γ9δ2 T cells. TCR spectratyping and CDR3 sequencing demonstrated that BCG-expanded γ9δ2 T cells expressed significantly less TCR sequence diversity than IPP-expanded γ9δ2 T cells. BCG-expanded γ9δ2 T cells respond similarly to BCG- and IPP-stimulation, while IPP-expanded γ9δ2 T cells responded poorly to BCG. BCG appears to stimulate an antigen-specific focusing event in γ9δ2 T cells while IPP acts like a mitogen with broad γ9δ2 T cell reactivity. The antigens and/or co-stimulatory signals required to induce protective γ9δ2 T cells remain to be identified.

Support: NIH R01-AI-48391, VTEU NO1-AI-25464

Crystallization and X-ray diffraction analysis of the complement component-3 (C3) inhibitory domain of Efb from Staphylococcus aureus

The extracellular fibrinogen-binding protein (Efb) of Staphylococcus aureus is a multifunctional virulence factor capable of potent inhibition of complement component-3 (C3) activity in addition to its previously described fibrinogen-binding properties. A truncated recombinant form of Efb (Efb-C) that binds C3 has been overexpressed and purified and has been crystallized using the hanging-drop vapor-diffusion technique. Crystals of native Efb-C grew in the tetragonal space group P4(3) (unit-cell parameters a = b = 59.53, c = 46.63 A) with two molecules in the asymmetric unit and diffracted well beyond 1.25 A limiting Bragg spacing. To facilitate de novo phasing of the Efb-C crystals, two independent site-directed mutants were engineered in which either residue Ile112 or Val140 was replaced with methionine and crystals isomorphous to those of native Efb-C were reproduced using a seleno-L-methionine-labeled form of each mutant protein. Multiwavelength anomalous diffraction (MAD) data were collected on both mutants and analyzed for their phasing power toward solution and refinement of a high-resolution Efb-C crystal structure.

Ventricular arrhythmia in the X-linked cardiomyopathy Barth syndrome

Barth syndrome is an X-linked disorder characterized by dilated cardiomyopathy, cyclic neutropenia, skeletal myopathy, abnormal mitochondria, and growth deficiency. The primary defect is a mutation in the TAZ gene on the X chromosome at Xq28, resulting in abnormal phospholipid biosynthesis and cardiolipin deficiency. To date, there has been no systematic evaluation of the cardiac phenotype. We report five cases of cardiac arrest and/or placement of an internal cardiac defibrillator with documented ventricular arrhythmia. We suggest that ventricular arrhythmia is part of the primary phenotype of the disorder and that patients should be screened accordingly.

Job satisfaction among medical technologists: an analysis of selected job-related variables

A survey was conducted of the graduates of a medical technology program to assess their feelings about their jobs. Specifically, the study attempted to determine the relationship between a "sense of accomplishment" and "career commitment." The relationship between job satisfaction and sense of accomplishment was also studied. Analysis using chi-square revealed a relationship between the respondent's sense of accomplishment and career commitment. Responses on accomplishment were then compared in terms of the graduates' ratings of selected job characteristics. These findings are compatible with those of other studies on job satisfaction of medical technologists. That is, medical technologists are a group whose motivational factors tend to be intrinisic to the job. These factors can be identified as achievement, recognition for achievement, the work itself, responsibility, and growth or advancement. The findings have implications for determining components related to job satisfaction in administrative practices.