IU Indianapolis ScholarWorks :: Browsing by Author "Brutkiewicz, Randy R."

Browsing by Author "Brutkiewicz, Randy R."

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Allergic Airway Disease in Mice Alters T and B Cell Responses during an Acute Respiratory Poxvirus Infection
(Public Library of Science, 2013-04-19) Walline, Crystal C.; Sehra, Sarita; Fisher, Amanda J.; Guindon, Lynette M.; Kratzke, Ian M.; Montgomery, Jessica B.; Lipking, Kelsey P.; Glosson, Nicole L.; Benson, Heather L.; Sandusky, George E.; Wilkes, David S.; Brutkiewicz, Randy R.; Kaplan, Mark H.; Blum, Janice S.; Microbiology and Immunology, School of Medicine
Pulmonary viral infections can exacerbate or trigger the development of allergic airway diseases via multiple mechanisms depending upon the infectious agent. Respiratory vaccinia virus transmission is well established, yet the effects of allergic airway disease on the host response to intra-pulmonary vaccinia virus infection remain poorly defined. As shown here BALB/c mice with preexisting airway disease infected with vaccinia virus developed more severe pulmonary inflammation, higher lung virus titers and greater weight loss compared with mice inoculated with virus alone. This enhanced viremia was observed despite increased pulmonary recruitment of CD8(+) T effectors, greater IFNγ production in the lung, and high serum levels of anti-viral antibodies. Notably, flow cytometric analyses of lung CD8(+) T cells revealed a shift in the hierarchy of immunodominant viral epitopes in virus inoculated mice with allergic airway disease compared to mice treated with virus only. Pulmonary IL-10 production by T cells and antigen presenting cells was detected following virus inoculation of animals and increased dramatically in allergic mice exposed to virus. IL-10 modulation of host responses to this respiratory virus infection was greatly influenced by the localized pulmonary microenvironment. Thus, blocking IL-10 signaling in virus-infected mice with allergic airway disease enhanced pulmonary CD4(+) T cell production of IFNγ and increased serum anti-viral IgG1 levels. In contrast, pulmonary IFNγ and virus-specific IgG1 levels were reduced in vaccinia virus-treated mice with IL-10 receptor blockade. These observations demonstrate that pre-existing allergic lung disease alters the quality and magnitude of immune responses to respiratory poxviruses through an IL-10-dependent mechanism.
Alterations in cellular metabolism modulate CD1d-mediated NKT-cell responses
(Oxford, 2016-08) Webb, Tonya J.; Carey, Gregory B.; East, James E.; Sun, Wenji; Bollino, Dominique R.; Kimball, Amy S.; Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
Natural killer T (NKT) cells play a critical role in the host's innate immune response. CD1d-mediated presentation of glycolipid antigens to NKT cells has been established; however, the mechanisms by which NKT cells recognize infected or cancerous cells remain unclear. 5′-AMP activated protein kinase (AMPK) is a master regulator of lipogenic pathways. We hypothesized that activation of AMPK during infection and malignancy could alter the repertoire of antigens presented by CD1d and serve as a danger signal to NKT cells. In this study, we examined the effect of alterations in metabolism on CD1d-mediated antigen presentation to NKT cells and found that an infection with lymphocytic choriomeningitis virus rapidly increased CD1d-mediated antigen presentation. Hypoxia inducible factors (HIF) enhance T-cell effector functions during infection, therefore antigen presenting cells pretreated with pharmacological agents that inhibit glycolysis, induce HIF and activate AMPK were assessed for their ability to induce NKT-cell responses. Pretreatment with 2-deoxyglucose, cobalt chloride, AICAR and metformin significantly enhanced CD1d-mediated NKT-cell activation. In addition, NKT cells preferentially respond to malignant B cells and B-cell lymphomas express HIF-1α. These data suggest that targeting cellular metabolism may serve as a novel means of inducing innate immune responses.
Anthrax Lethal Toxin Impairs CD1d-Mediated Antigen Presentation by Targeting the Extracellular Signal-Related Kinase 1/2 Mitogen-Activated Protein Kinase Pathway
(American Society for Microbiology, 2010-05) Khan, Masood A.; Gallo, Richard M.; Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
Lethal toxin (LT) is a critical virulence factor of Bacillus anthracis and an important means by which this bacterium evades the host's immune system. In this study, we demonstrate that CD1d-expressing cells treated with LT have reduced CD1d-mediated antigen presentation. We earlier showed an important role for the mitogen-activated protein kinase extracellular signal-regulated kinase 1/2 (ERK1/2) in the regulation of CD1d-mediated antigen presentation, and we report here that LT impairs antigen presentation by CD1d in an ERK1/2-dependent manner. Similarly, LT and the ERK1/2 pathway-specific inhibitor U0126 caused a decrease in major histocompatibility complex (MHC) class II-mediated antigen presentation. Confocal microscopy analyses revealed altered intracellular distribution of CD1d and LAMP-1 in LT-treated cells, similar to the case for ERK1/2-inhibited cells. These results suggest that Bacillus anthracis has the ability to evade the host's innate immune system by reducing CD1d-mediated antigen presentation through targeting the ERK1/2 pathway.
Blocking the innate immune CD1d/NKT cell axis prevents the development of cortical hyperexcitability and posttraumatic epilepsy
(Wiley, 2025) Ping, Xingjie; Xiong, Wenhui; Priya, Raj; Liu, Jianyun; Wyatt-Johnson, Season K.; Brutkiewicz, Randy R.; Jin, Xiaoming; Anatomy, Cell Biology and Physiology, School of Medicine
Objective: Posttraumatic epilepsy (PTE) that develops after a traumatic brain injury (TBI) cannot be prevented by current treatments. Although neuroinflammation is involved in epileptogenesis, a potential role for cellular immunity in this process is largely unknown. Natural killer T (NKT) cells are innate-like T lymphocytes that recognize lipid antigens presented by the major histocompatibility complex class I-like CD1d molecule and play a crucial role in regulating immune responses. Herein we examined the role of the CD1d/NKT cell axis in PTE. Methods: We used an undercut surgery to induce TBI in wild-type (WT) and CD1d-deficient (CD1d knockout [KO], CD1d KO) or NKT cell-deficient (Traj18 KO) mice. A pentylenetetrazol (PTZ) test was used to determine seizure susceptibility in vivo, and field potential recordings were made from cortical slices in vitro. Continuous video and wireless EEG monitoring was undertaken of WT and CD1d KO mice between 5 and 8 weeks after brain injury. Because statins are known to impair antigen presentation by CD1d to NKT cells, we also treated WT mice with simvastatin for 10 days after injury and performed the PTZ test. Immunofluorescence and flow cytometry were used to determine changes in immune cells in brain tissue. Results: CD1d KO or Traj18 KO TBI mice had a significantly lower seizure susceptibility than WT mice on the PTZ test. CD1d KO mice had a significantly lower rate of detectable epileptiform activities during field potential recording. Video and EEG monitoring showed that CD1d KO TBI mice had a significantly lower frequency of spontaneous epileptic seizures. There was increased infiltration of immune cells, but reduced microgliosis in the brains of these mice. Simvastatin treatment significantly reduced seizure susceptibility in TBI mice. Significance: Neuroinflammation initiated by the CD1d/NKT cell axis is involved in the development of cortical hyperexcitability and PTE; early treatment with simvastatin following a TBI exerts a prophylactic effect on posttraumatic epileptogenesis by blocking this axis.
Brain astrocytes and microglia express functional MR1 molecules that present microbial antigens to mucosal-associated invariant T (MAIT) cells
(Elsevier, 2020-12-15) Priya, Raj; Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
It is unknown whether brain astrocytes and microglia have the capacity to present microbial antigens via the innate immune MR1/MAIT cell axis. We have detected MAIT cells in the normal mouse brain and found that both astrocytes and microglia are MR1+. When we stimulated brain astrocytes and microglia with E. coli, and then co-cultured them with MAIT cells, MR1 surface expression was upregulated and MAIT cells were activated in an antigen-dependent manner. Considering the association of MAIT cells with inflammatory conditions, including those in the CNS, the MR1/MAIT cell axis could be a novel therapeutic target in neuroinflammatory disorders.
Cell Signaling Pathways that Regulate Ag Presentation
(American Association of Immunologists, 2016-10-15) Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
Cell signaling pathways regulate much in the life of a cell: from shuttling cargo through intracellular compartments and onto the cell surface, how it should respond to stress, protecting itself from harm (environmental insults or infections), to ultimately, death by apoptosis. These signaling pathways are important for various aspects of the immune response as well. However, not much is known in terms of the participation of cell signaling pathways in Ag presentation--a necessary first step in the activation of innate and adaptive T cells. In this brief review, I will discuss the known signaling molecules (and pathways) that regulate how Ags are presented to T cells and the mechanism(s) if identified. Studies in this area have important implications in vaccine development and new treatment paradigms against infectious diseases, autoimmunity and cancer.
Characterization of Hepatitis C Virus Infection of Hepatocytes and Astrocytes
(2014) Liu, Ziqing; Yu, Andy; He, Johnny J.; Brutkiewicz, Randy R.; Kao, Cheng C.; Sullivan, William J., Jr.
Approximately 2.8% of the world population is currently infected with hepatitis C virus (HCV). Neutralizing antibodies (nAbs) are often generated in chronic hepatitis C patients yet fail to control the infection. In the first two chapters of this study, we focused on two alternative routes of HCV transmission, which may contribute to HCV’s immune evasion and establishment of chronic infection. HCV was transmitted via a cell-cell contact-mediated (CCCM) route and in the form of exosomes. Formation of HCV infection foci resulted from CCCM HCV transfer and was cell density-dependent. Moreover, CCCM HCV transfer occurred rapidly, involved all four known HCV receptors and intact actin cytoskeleton, and led to productive HCV infection. Furthermore, live cell imaging revealed the temporal and spatial details of the transfer process. Lastly, HCV from HCV-infected hepatocytes and patient plasma occurred in both exosome-free and exosome-associated forms and the exosome-associated HCV remained infectious, even though HCV infection did not significantly alter exosome secretion. In the third chapter, we characterized HCV interaction with astrocytes, one of the putative HCV target cells in the brain. HCV infection causes the central nervous system (CNS) abnormalities in more than 50% of chronically infected subjects but the underlying mechanisms are largely unknown. We showed that primary human astrocytes (PHA) were very inefficiently infected by HCV, either in the free virus form or through cell-cell contact. PHA expressed all known HCV receptors but failed to support HCV entry. HCV IRES-mediated translation was functional in PHA and further enhanced by miR122 expression. Nevertheless, PHA did not support HCV replication regardless of miR122 expression. To our great surprise, HCV exposure induced robust IL-18 expression in PHA and exhibited direct neurotoxicity. In summary, we showed that CCCM HCV transfer and exosome-mediated HCV infection constituted important routes for HCV infection and dissemination and that astrocytes did not support productive HCV infection and replication, but HCV interactions with astrocytes and neurons alone might be sufficient to cause CNS dysfunction. These findings provide new insights into HCV infection of hepatocytes and astrocytes and shall aid in the development of new and effective strategies for preventing and treating HCV infection.
The Complexity of Microglial Interactions With Innate and Adaptive Immune Cells in Alzheimer’s Disease
(Frontiers Media, 2020-11-19) Wyatt-Johnson, Season K.; Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
In the naïve mouse brain, microglia and astrocytes are the most abundant immune cells; however, there is a complexity of other immune cells present including monocytes, neutrophils, and lymphocytic cells, such as natural killer (NK) cells, T cells, and B cells. In Alzheimer’s disease (AD), there is high inflammation, reactive microglia, and astrocytes, leaky blood–brain barrier, the buildup of amyloid-beta (Aβ) plaques, and neurofibrillary tangles which attract infiltrating peripheral immune cells that are interacting with the resident microglia. Limited studies have analyzed how these infiltrating immune cells contribute to the neuropathology of AD and even fewer have analyzed their interactions with the resident microglia. Understanding the complexity and dynamics of how these immune cells interact in AD will be important for identifying new and novel therapeutic targets. Thus, this review will focus on discussing our current understanding of how macrophages, neutrophils, NK cells, T cells, and B cells, alongside astrocytes, are altered in AD and what this means for the disorder, as well as how these cells are affected relative to the resident microglia.
Control of the temporal development of Alzheimer's disease pathology by the MR1/MAIT cell axis
(BMC, 2023-03-21) Wyatt‑Johnson, Season K.; Kersey, Holly N.; Codocedo, Juan F.; Newell, Kathy L.; Landreth, Gary E.; Lamb, Bruce T.; Oblak, Adrian L.; Brutkiewicz, Randy R.; Microbiology and Immunology, School of Medicine
Background: Neuroinflammation is an important feature of Alzheimer's disease (AD). Understanding which aspects of the immune system are important in AD may lead to new therapeutic approaches. We study the major histocompatibility complex class I-related immune molecule, MR1, which is recognized by an innate-like T cell population called mucosal-associated invariant T (MAIT) cells. Methods: Having found that MR1 gene expression is elevated in the brain tissue of AD patients by mining the Agora database, we sought to examine the role of the MR1/MAIT cell axis in AD pathology. Brain tissue from AD patients and the 5XFAD mouse model of AD were used to analyze MR1 expression through qPCR, immunofluorescence, and flow cytometry. Furthermore, mice deficient in MR1 and MAIT cells were crossed with the 5XFAD mice to produce a model to study how the loss of this innate immune axis alters AD progression. Moreover, 5XFAD mice were also used to study brain-resident MAIT cells over time. Results: In tissue samples from AD patients and 5XFAD mice, MR1 expression was substantially elevated in the microglia surrounding plaques vs. those that are further away (human AD: P < 0.05; 5XFAD: P < 0.001). In 5XFAD mice lacking the MR1/MAIT cell axis, the development of amyloid-beta plaque pathology occurred at a significantly slower rate than in those mice with MR1 and MAIT cells. Furthermore, in brain tissue from 5XFAD mice, there was a temporal increase in MAIT cell numbers (P < 0.01) and their activation state, the latter determined by detecting an upregulation of both CD69 (P < 0.05) and the interleukin-2 receptor alpha chain (P < 0.05) via flow cytometry. Conclusions: Together, these data reveal a previously unknown role for the MR1/MAIT cell innate immune axis in AD pathology and its potential utility as a novel therapeutic target.
Elucidating the Characteristics and Functionality of the Mouse Mucosal-Associated Mucosal Invariant T (MAIT) Cell Receptor
(2023-08) Shrinivasan, Rashmi; Brutkiewicz, Randy R.; Dent, Alexander L.; Tran, Ngoc Tung
Mucosal-associated invariant T cells (MAIT) are a subset of invariant, innate-like T-cells that are abundant in the gut lamina propria, kidney, lungs, and peripheral blood. MAIT cells are stimulated by the recognition of microbial vitamin B-derived metabolites by the MHC class I-like molecule, MR1. Recent studies have implicated MAIT cells in several autoimmune diseases, various cancers, and CNS disorders, making it essential to design animal models that replicate the human disease state. The relatively small population of MAIT cells in mice makes it difficult to isolate and characterize them. The MAIT cell receptor (TCR) is comprised of a Vα7.2-Jα33 rearrangement in humans and TRAV1-TRAJ33 in mice. This project aimed to create a tool to study mouse MAIT cells in detail by generating lentiviral plasmid constructs expressing cDNAs encoding the MAIT cell TCR α and β chains that will be ectopically expressed in TCR-deficient mouse T cells. A bulk TCR analysis of the mouse MR1-restricted MAIT hybridomas 6C2 and 8D12 was performed to confirm variable and joining regions in the TCR α and β chains. This analysis confirmed the proper MAIT cell TCR usage in the MAIT cell hybridomas. As both MAIT cell hybridomas can be stimulated by MR1-presented antigens, we obtained synthetic cDNAs that were generated for the TRAV1-TRAJ33 α chain and TRBV8.2 (TRBV13-2) β chain. These were subcloned into GFP- and mCherry-expressing plasmids and packaged into lentiviruses that will be used for transduction of TCR-deficient mouse T cells. Flow cytometry and ELISAs will ultimately be performed to confirm the functional expression of the MAIT cell TCR. These tools will greatly facilitate the investigation of MAIT cell function in vitro and the ultimate generation of retrogenic mice for the tracking of MAIT cells in vivo.

Browsing by Author "Brutkiewicz, Randy R."

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