CD8 T cells comprising the memory pool display considerable heterogeneity, with individual cells ... more CD8 T cells comprising the memory pool display considerable heterogeneity, with individual cells differing in phenotype and function. This review will focus on our current understanding of heterogeneity within the antigen-specific memory CD8 T cell compartment and classifications of memory CD8 T cell subsets with defined and discrete functionalities. Recent data suggest that phenotype and/or function of numerically stable circulatory memory CD8 T cells are defined by the age of memory CD8 T cell (or time after initial antigen-encounter). In addition, history of antigen stimulations has a profound effect on memory CD8 T cell populations, suggesting that repeated infections (or vaccination) have the capacity to further shape the memory CD8 T cell pool. Finally, genetic background of hosts and history of exposure to diverse microorganisms likely contribute to the observed heterogeneity in the memory CD8 T cell compartment. Extending our tool box and exploring alternative mouse models (i.e., "dirty" and/or outbred mice) to encompass and better model diversity observed in humans will remain an important goal for the near future that will likely shed new light into the mechanisms that govern biology of memory CD8 T cells.
Mortality from sepsis frequently results from secondary infections, and the extent to which sepsi... more Mortality from sepsis frequently results from secondary infections, and the extent to which sepsis affects pathogen-specific memory CD8 T cell responses remains unknown. Using the cecal ligation and puncture model of polymicrobial sepsis, we observed rapid apoptosis of pre-existing memory CD8 T cells after sepsis induction that led to a loss in CD8 T cell–mediated protection. Ag sensitivity (functional avidity) and Ag-driven secondary expansion of memory CD8 T cells were decreased after sepsis, further contributing to the observed loss in CD8 T cell–mediated immunity. Moreover, Ag-independent bystander activation of memory CD8 T cells in response to heterologous infection was also significantly impaired early after sepsis induction. The reduced sensitivity of pre-existing memory CD8 T cells to sense inflammation and respond to heterologous infection by IFN-γ production was observed in inbred and outbred hosts and controlled by extrinsic (but not cell-intrinsic) factors, suggesting t...
Osimertinib is an EGFR tyrosine kinase inhibitor (TKI) with proven clinical efficacy; however, ac... more Osimertinib is an EGFR tyrosine kinase inhibitor (TKI) with proven clinical efficacy; however, acquired resistance presents an obstacle to curing EGFR-driven disease. Recent studies have shown that drug-tolerant persister cells (DTP) have a distinct transcriptional profile that may confer specific vulnerabilities. By definition these cells avoid apoptosis, yet little is known about how their survival is regulated. We found that paradoxically, the proapoptotic gene BIM was upregulated in osimertinib DTPs, and cotreatment with BH3 mimetics could trigger DTP cell death. Furthermore, cIAP proteins, antiapoptotic members of the extrinsic pathway, were significantly elevated in DTPs. cIAP antagonists could block DTP formation as an up-front combination, and could eliminate preformed DTPs. Critically, when treated at the time of maximal osimertinib response, cIAP or MCL1 inhibitor treatment could significantly attenuate the regrowth of EGFRm cell line mouse xenografts. Finally, we show tha...
The neurological and psychological characteristics of adolescence make adolescents particularly v... more The neurological and psychological characteristics of adolescence make adolescents particularly vulnerable to recruitment tactics employed by fringe and antisocial groups. ISIL is not the first group to take advantage of adolescents’ vulnerabilities, but the group has become particularly adept at doing so. Undermining their influence among potential recruits in this age range requires an understanding of the adolescents’ state of mind and brain; counter-messages that are intuitively appealing to older adults may be ineffective, or even counter-productive among this audience. In particular, messages directed to adolescents should (1) focus on emotionally impactful messages instead of logical arguments, (2) avoid emphasizing the risks associated with joining ISIL, and (3) undermine ISIL’s claims to provide belongingness and peer affiliation and provide alternate means for social acceptance. Introduction On February 23, 2016 the government of Iraq’s semi-autonomous Kurdish region repor...
The question of the extent to which porcelain figures were considered sculpture that is, figural ... more The question of the extent to which porcelain figures were considered sculpture that is, figural works bearing an independent meaning, viewed and engaged with as such, rather than objects which were seen as components subsumed into a larger decorative scheme in mid eighteenth-century England is one of interest. In general, porcelain has acquired overwhelmingly decorative connotations in art historical discourse and this has overshadowed its place in sculptural aesthetics. The medium falls foul of the aesthetic critiques of neoclassical theorists such as Winckelmann and Goethe, as it is seen to embody the phenomena of material illusionism (one material being employed to imitate another) and miniaturisation, both identified by Ludwig Giesz in his influential study Phdnomenologie des Kitsches as art historical criteria for kitsch.. The failure to consider the work of the modeller of porcelain figures as an exercise in compositional creativity is symptomatic of the more general failure ...
Recent work has suggested that current mouse models may underrepresent the complexity of human im... more Recent work has suggested that current mouse models may underrepresent the complexity of human immune responses. While most mouse immunology studies utilize inbred mouse strains, it is unclear if conclusions drawn from inbred mice can be extended to all mouse strains or generalized to humans. We recently described a "surrogate activation marker" approach that could be used to track polyclonal CD8 T cell responses in inbred and outbred mice and noted substantial discord in the magnitude and kinetics of CD8 T cell responses in individual outbred mice following infection. However, how the memory CD8 T cell response develops following infection and the correlates of memory CD8 T cell-mediated protection against re-infection in outbred mice remains unknown. In this study, we investigated development of pathogen-specific memory CD8 T cell responses in inbred C57B/6 and outbred National Institutes of Health Swiss mice following lymphocytic choriomeningitis virus or L. monocytogen...
Background and Purpose. Initiation of gait requires transitions from relatively stationary positi... more Background and Purpose. Initiation of gait requires transitions from relatively stationary positions to stability with movement and from double- to single-limb stances. These are deliberately destabilizing activities that may be difficult for people with early Parkinson disease (PD), even when they have no problems with level walking. We studied differences in postural stability during gait initiation between participants with early and middle stages of PD (characterized by Hoehn and Yahr as stages 1–3) and 2 other groups of participants without PD—older and younger adults. Subjects. The mean ages of the 3 groups of participants were as follows: subjects with PD, 69.3 years (SD=5.7, range=59–78); older subjects without PD, 69.0 years (SD=3.9, range=65–79); and younger subjects without PD, 27.5 (SD=3.9, range=22–35). Methods. A 3-dimensional motion analysis system was used with 2 force platforms to obtain data for center of mass (COM) and center of pressure (COP). The distance betwee...
Journal of biomedical materials research. Part A, Feb 11, 2017
Peripheral nerve possesses the inherent ability to regrow and recover following injury. However, ... more Peripheral nerve possesses the inherent ability to regrow and recover following injury. However, nerve regeneration is often slow and incomplete due to limitations associated with the local microenvironment during the repair process. Manipulation of the local microenvironment at the site of nerve repair, therefore, represents a significant opportunity for improvement in downstream outcomes. Macrophages and Schwann cells play a key role in the orchestration of early events after peripheral nerve injury. We describe the production, characterization, and use of an injectable, peripheral nerve-specific extracellular matrix-based hydrogel (PNSECM) for promoting modulation of the local macrophage and Schwann cell responses at the site of nerve repair in a rodent model of sciatic nerve injury. We show that PNSECM hydrogels largely maintain the matrix structure associated with normal native peripheral nerve tissue. PNSECM hydrogels were also found to promote increased macrophage invasion, h...
Activated CD8(+) T cells differentiate into cytotoxic effector (TEFF) cells that eliminate target... more Activated CD8(+) T cells differentiate into cytotoxic effector (TEFF) cells that eliminate target cells. How TEFF cell identity is established and maintained is not fully understood. We found that Runx3 deficiency limited clonal expansion and impaired upregulation of cytotoxic molecules in TEFF cells. Runx3-deficient CD8(+) TEFF cells aberrantly upregulated genes characteristic of follicular helper T (TFH) cell lineage, including Bcl6, Tcf7 and Cxcr5. Mechanistically, the Runx3-CBFβ transcription factor complex deployed H3K27me3 to Bcl6 and Tcf7 genes to suppress the TFH program. Ablating Tcf7 in Runx3-deficient CD8(+) TEFF cells prevented the upregulation of TFH genes and ameliorated their defective induction of cytotoxic genes. As such, Runx3-mediated Tcf7 repression coordinately enforced acquisition of cytotoxic functions and protected the cytotoxic lineage integrity by preventing TFH-lineage deviation.
Memory CD8 T cells can be activated and induced to produce cytokines and increase stores of cytol... more Memory CD8 T cells can be activated and induced to produce cytokines and increase stores of cytolytic proteins not only in response to cognate antigen (Ag) but also in response to inflammatory cytokines (bystander responses). Importantly, bystander memory CD8 T cell functions have been shown to be dependent upon memory CD8 T cell fitness, since exhausted CD8 T cells have diminished capacity to respond to inflammatory cues. While it is known that memory CD8 T cell functional abilities, including ability to produce cytokines in response to cognate Ag, change with time after initial Ag encounter and upon multiple Ag stimulations (e.g., primary vs. tertiary CD8 T cell responses), it is unknown if bystander memory CD8 T cell responses are influenced by time or by Ag-exposure history. Here, we examined time and Ag-stimulation history-dependent alterations in virus-specific memory CD8 T cell bystander functions in response to inflammatory cytokines and unrelated bacterial infection. We fou...
Unlike systemic infections, little is known about the role of repeated localized infections on (r... more Unlike systemic infections, little is known about the role of repeated localized infections on (re)shaping pathogen-specific memory CD8 T cell responses. Here, we used primary (1°) and secondary (2°) intranasal influenza virus infections of mice as a model to study intrinsic memory CD8 T cell properties. We show that secondary antigen exposure, relative to a single infection, generates memory CD8 T cell responses of superior magnitude in multiple tissue compartments including blood, spleen, draining lymph nodes, and lung. Unexpectedly, regardless of the significantly higher number of 2° memory CD8 T cells, similar degree of protection against pulmonary challenge was observed in both groups of mice containing 1° or 2° memory CD8 T cells. Mechanistically, using pertussis toxin-induced migration block, we showed that superior antigen-driven proliferation and ability to relocate to the site of infection allowed 1° memory CD8 T cells to accumulate in the infected lung during the first fe...
Metabolic plasticity is an emerging hallmark of cancer, and increased glycolysis is often observe... more Metabolic plasticity is an emerging hallmark of cancer, and increased glycolysis is often observed in transformed cells. Small molecule inhibitors that target driver oncogenes can potentially inhibit the glycolytic pathway. Osimertinib (AZD9291) is a novel EGFR tyrosine kinase inhibitor (TKI) that is potent and selective for sensitising (EGFRm) and T790M resistance mutations. Clinical studies have shown osimertinib to be efficacious in patients with EGFRm/ T790M advanced NSCLC who have progressed after EGFR-TKI treatment. However experience with targeted therapies suggests that acquired resistance may emerge. Thus there is a need to characterize resistance mechanisms and to devise ways to prevent, delay or overcome osimertinib resistance. We show here that osimertinib suppresses glycolysis in parental EGFR-mutant lung adenocarcinoma lines, but has not in osimertinib-resistant cell lines. Critically, we show osimertinib treatment induces a strict dependence on mitochondrial oxidative...
Differentiation of effector and memory CD8(+) T cells is accompanied by extensive changes in the ... more Differentiation of effector and memory CD8(+) T cells is accompanied by extensive changes in the transcriptome and histone modifications at gene promoters; however, the enhancer repertoire and associated gene regulatory networks are poorly defined. Using histone mark chromatin immunoprecipitation coupled with deep sequencing, we mapped the enhancer and super-enhancer landscapes in antigen-specific naive, differentiated effector, and central memory CD8(+) T cells during LCMV infection. Epigenomics-based annotation revealed a highly dynamic repertoire of enhancers, which were inherited, de novo activated, decommissioned and re-activated during CD8(+) T cell responses. We employed a computational algorithm to pair enhancers with target gene promoters. On average, each enhancer targeted three promoters and each promoter was regulated by two enhancers. By identifying enriched transcription factor motifs in enhancers, we defined transcriptional regulatory circuitry at each CD8(+) T cell r...
In this issue of Immunity, Gerlach et al. (2016) describe three distinct memory CD8(+) T cell sub... more In this issue of Immunity, Gerlach et al. (2016) describe three distinct memory CD8(+) T cell subsets based upon expression of the fractalkine receptor CX3CR1. Their findings revise the paradigm of effector and central memory T cells by revealing a subset of CD8(+) memory T cells defined by intermediate levels of expression of CX3CR1 that conducts tissue surveillance.
Quantification of the number of axons reinnervating a target organ is often used to assess regene... more Quantification of the number of axons reinnervating a target organ is often used to assess regeneration after peripheral nerve repair, but because of axonal branching, this method can overestimate the number of motor neurons regenerating across an injury. Current methods to count the number of regenerated motor neurons include retrograde labeling followed by cryosectioning and counting labeled motor neuron cell bodies, however, the process of sectioning introduces error from potential double counting of cells in adjacent sections. We describe a method, retroDISCO, that optically clears whole mouse spinal cord without loss of fluorescent signal to allow imaging of retrograde labeled motor neurons using confocal microscopy. Complete optical clearing of spinal cords takes four hours and confocal microscopy can obtain z-stacks of labeled motor neuron pools within 3-5minutes. The technique is able to detect anticipated differences in motor neuron number after cross-suture and conduit rep...
The efficacy and safety of proton pump inhibitors vs histamine-2 receptor antagonists for stress ... more The efficacy and safety of proton pump inhibitors vs histamine-2 receptor antagonists for stress ulcer bleeding prophylaxis among critical care patients: A meta-analysis.
Memory CD8 T-cell activation, including expression of IFN-γ and granzymeB, can be induced by anti... more Memory CD8 T-cell activation, including expression of IFN-γ and granzymeB, can be induced by antigen (Ag)-dependent signals through the T-cell-receptor, or by pathogen-derived inflammatory cytokines in an Ag-independent manner. Recent studies have come to conflicting results regarding the contributions of Ag and/or inflammation to memory CD8 T-cell activation. Additionally, research has indicated that inflammation-driven CD8 T-cell responses during un-related infections (bystander activation) have the potential to provide protection, but whether protection occurs in immuno-competent hosts is unclear. To investigate these questions, we examined activation of virus-specific memory CD8 T-cells following infection with L. monocytogenes either expressing or not cognate Ag. We show that Ag and inflammation act synergistically in vitro to induce memory activation. In vivo, we found that when memory CD8 T-cells significantly contribute to clearance of infection, early activation and continu...
Many organelles and vesicles in live cells move in a start-stop manner when observed for ~10 s by... more Many organelles and vesicles in live cells move in a start-stop manner when observed for ~10 s by optical microscopy. Changes in velocity and directional persistence of such particles are a potentially rich source of insight into the mechanisms leading to the start and stop states. Unbiased assessment of the most probable number of states, the properties of each state, and the most probable state for the particle at each moment can be accomplished by variational Bayesian methods combined with a hidden Markov model and a Gaussian mixture model. Our track analysis method, "vbTRACK", applied this combination of methods to particle velocity v or changes in the direction of travel evaluated from simulated tracks and from tracks of peroxisomes in live cells. When tested with numerical data, vbTRACK reliably determined the number of states, the mean and variance of the velocity or the direction of travel for each state, and the most probable state during each frame. When applied ...
CD8 T cells comprising the memory pool display considerable heterogeneity, with individual cells ... more CD8 T cells comprising the memory pool display considerable heterogeneity, with individual cells differing in phenotype and function. This review will focus on our current understanding of heterogeneity within the antigen-specific memory CD8 T cell compartment and classifications of memory CD8 T cell subsets with defined and discrete functionalities. Recent data suggest that phenotype and/or function of numerically stable circulatory memory CD8 T cells are defined by the age of memory CD8 T cell (or time after initial antigen-encounter). In addition, history of antigen stimulations has a profound effect on memory CD8 T cell populations, suggesting that repeated infections (or vaccination) have the capacity to further shape the memory CD8 T cell pool. Finally, genetic background of hosts and history of exposure to diverse microorganisms likely contribute to the observed heterogeneity in the memory CD8 T cell compartment. Extending our tool box and exploring alternative mouse models (i.e., "dirty" and/or outbred mice) to encompass and better model diversity observed in humans will remain an important goal for the near future that will likely shed new light into the mechanisms that govern biology of memory CD8 T cells.
Mortality from sepsis frequently results from secondary infections, and the extent to which sepsi... more Mortality from sepsis frequently results from secondary infections, and the extent to which sepsis affects pathogen-specific memory CD8 T cell responses remains unknown. Using the cecal ligation and puncture model of polymicrobial sepsis, we observed rapid apoptosis of pre-existing memory CD8 T cells after sepsis induction that led to a loss in CD8 T cell–mediated protection. Ag sensitivity (functional avidity) and Ag-driven secondary expansion of memory CD8 T cells were decreased after sepsis, further contributing to the observed loss in CD8 T cell–mediated immunity. Moreover, Ag-independent bystander activation of memory CD8 T cells in response to heterologous infection was also significantly impaired early after sepsis induction. The reduced sensitivity of pre-existing memory CD8 T cells to sense inflammation and respond to heterologous infection by IFN-γ production was observed in inbred and outbred hosts and controlled by extrinsic (but not cell-intrinsic) factors, suggesting t...
Osimertinib is an EGFR tyrosine kinase inhibitor (TKI) with proven clinical efficacy; however, ac... more Osimertinib is an EGFR tyrosine kinase inhibitor (TKI) with proven clinical efficacy; however, acquired resistance presents an obstacle to curing EGFR-driven disease. Recent studies have shown that drug-tolerant persister cells (DTP) have a distinct transcriptional profile that may confer specific vulnerabilities. By definition these cells avoid apoptosis, yet little is known about how their survival is regulated. We found that paradoxically, the proapoptotic gene BIM was upregulated in osimertinib DTPs, and cotreatment with BH3 mimetics could trigger DTP cell death. Furthermore, cIAP proteins, antiapoptotic members of the extrinsic pathway, were significantly elevated in DTPs. cIAP antagonists could block DTP formation as an up-front combination, and could eliminate preformed DTPs. Critically, when treated at the time of maximal osimertinib response, cIAP or MCL1 inhibitor treatment could significantly attenuate the regrowth of EGFRm cell line mouse xenografts. Finally, we show tha...
The neurological and psychological characteristics of adolescence make adolescents particularly v... more The neurological and psychological characteristics of adolescence make adolescents particularly vulnerable to recruitment tactics employed by fringe and antisocial groups. ISIL is not the first group to take advantage of adolescents’ vulnerabilities, but the group has become particularly adept at doing so. Undermining their influence among potential recruits in this age range requires an understanding of the adolescents’ state of mind and brain; counter-messages that are intuitively appealing to older adults may be ineffective, or even counter-productive among this audience. In particular, messages directed to adolescents should (1) focus on emotionally impactful messages instead of logical arguments, (2) avoid emphasizing the risks associated with joining ISIL, and (3) undermine ISIL’s claims to provide belongingness and peer affiliation and provide alternate means for social acceptance. Introduction On February 23, 2016 the government of Iraq’s semi-autonomous Kurdish region repor...
The question of the extent to which porcelain figures were considered sculpture that is, figural ... more The question of the extent to which porcelain figures were considered sculpture that is, figural works bearing an independent meaning, viewed and engaged with as such, rather than objects which were seen as components subsumed into a larger decorative scheme in mid eighteenth-century England is one of interest. In general, porcelain has acquired overwhelmingly decorative connotations in art historical discourse and this has overshadowed its place in sculptural aesthetics. The medium falls foul of the aesthetic critiques of neoclassical theorists such as Winckelmann and Goethe, as it is seen to embody the phenomena of material illusionism (one material being employed to imitate another) and miniaturisation, both identified by Ludwig Giesz in his influential study Phdnomenologie des Kitsches as art historical criteria for kitsch.. The failure to consider the work of the modeller of porcelain figures as an exercise in compositional creativity is symptomatic of the more general failure ...
Recent work has suggested that current mouse models may underrepresent the complexity of human im... more Recent work has suggested that current mouse models may underrepresent the complexity of human immune responses. While most mouse immunology studies utilize inbred mouse strains, it is unclear if conclusions drawn from inbred mice can be extended to all mouse strains or generalized to humans. We recently described a "surrogate activation marker" approach that could be used to track polyclonal CD8 T cell responses in inbred and outbred mice and noted substantial discord in the magnitude and kinetics of CD8 T cell responses in individual outbred mice following infection. However, how the memory CD8 T cell response develops following infection and the correlates of memory CD8 T cell-mediated protection against re-infection in outbred mice remains unknown. In this study, we investigated development of pathogen-specific memory CD8 T cell responses in inbred C57B/6 and outbred National Institutes of Health Swiss mice following lymphocytic choriomeningitis virus or L. monocytogen...
Background and Purpose. Initiation of gait requires transitions from relatively stationary positi... more Background and Purpose. Initiation of gait requires transitions from relatively stationary positions to stability with movement and from double- to single-limb stances. These are deliberately destabilizing activities that may be difficult for people with early Parkinson disease (PD), even when they have no problems with level walking. We studied differences in postural stability during gait initiation between participants with early and middle stages of PD (characterized by Hoehn and Yahr as stages 1–3) and 2 other groups of participants without PD—older and younger adults. Subjects. The mean ages of the 3 groups of participants were as follows: subjects with PD, 69.3 years (SD=5.7, range=59–78); older subjects without PD, 69.0 years (SD=3.9, range=65–79); and younger subjects without PD, 27.5 (SD=3.9, range=22–35). Methods. A 3-dimensional motion analysis system was used with 2 force platforms to obtain data for center of mass (COM) and center of pressure (COP). The distance betwee...
Journal of biomedical materials research. Part A, Feb 11, 2017
Peripheral nerve possesses the inherent ability to regrow and recover following injury. However, ... more Peripheral nerve possesses the inherent ability to regrow and recover following injury. However, nerve regeneration is often slow and incomplete due to limitations associated with the local microenvironment during the repair process. Manipulation of the local microenvironment at the site of nerve repair, therefore, represents a significant opportunity for improvement in downstream outcomes. Macrophages and Schwann cells play a key role in the orchestration of early events after peripheral nerve injury. We describe the production, characterization, and use of an injectable, peripheral nerve-specific extracellular matrix-based hydrogel (PNSECM) for promoting modulation of the local macrophage and Schwann cell responses at the site of nerve repair in a rodent model of sciatic nerve injury. We show that PNSECM hydrogels largely maintain the matrix structure associated with normal native peripheral nerve tissue. PNSECM hydrogels were also found to promote increased macrophage invasion, h...
Activated CD8(+) T cells differentiate into cytotoxic effector (TEFF) cells that eliminate target... more Activated CD8(+) T cells differentiate into cytotoxic effector (TEFF) cells that eliminate target cells. How TEFF cell identity is established and maintained is not fully understood. We found that Runx3 deficiency limited clonal expansion and impaired upregulation of cytotoxic molecules in TEFF cells. Runx3-deficient CD8(+) TEFF cells aberrantly upregulated genes characteristic of follicular helper T (TFH) cell lineage, including Bcl6, Tcf7 and Cxcr5. Mechanistically, the Runx3-CBFβ transcription factor complex deployed H3K27me3 to Bcl6 and Tcf7 genes to suppress the TFH program. Ablating Tcf7 in Runx3-deficient CD8(+) TEFF cells prevented the upregulation of TFH genes and ameliorated their defective induction of cytotoxic genes. As such, Runx3-mediated Tcf7 repression coordinately enforced acquisition of cytotoxic functions and protected the cytotoxic lineage integrity by preventing TFH-lineage deviation.
Memory CD8 T cells can be activated and induced to produce cytokines and increase stores of cytol... more Memory CD8 T cells can be activated and induced to produce cytokines and increase stores of cytolytic proteins not only in response to cognate antigen (Ag) but also in response to inflammatory cytokines (bystander responses). Importantly, bystander memory CD8 T cell functions have been shown to be dependent upon memory CD8 T cell fitness, since exhausted CD8 T cells have diminished capacity to respond to inflammatory cues. While it is known that memory CD8 T cell functional abilities, including ability to produce cytokines in response to cognate Ag, change with time after initial Ag encounter and upon multiple Ag stimulations (e.g., primary vs. tertiary CD8 T cell responses), it is unknown if bystander memory CD8 T cell responses are influenced by time or by Ag-exposure history. Here, we examined time and Ag-stimulation history-dependent alterations in virus-specific memory CD8 T cell bystander functions in response to inflammatory cytokines and unrelated bacterial infection. We fou...
Unlike systemic infections, little is known about the role of repeated localized infections on (r... more Unlike systemic infections, little is known about the role of repeated localized infections on (re)shaping pathogen-specific memory CD8 T cell responses. Here, we used primary (1°) and secondary (2°) intranasal influenza virus infections of mice as a model to study intrinsic memory CD8 T cell properties. We show that secondary antigen exposure, relative to a single infection, generates memory CD8 T cell responses of superior magnitude in multiple tissue compartments including blood, spleen, draining lymph nodes, and lung. Unexpectedly, regardless of the significantly higher number of 2° memory CD8 T cells, similar degree of protection against pulmonary challenge was observed in both groups of mice containing 1° or 2° memory CD8 T cells. Mechanistically, using pertussis toxin-induced migration block, we showed that superior antigen-driven proliferation and ability to relocate to the site of infection allowed 1° memory CD8 T cells to accumulate in the infected lung during the first fe...
Metabolic plasticity is an emerging hallmark of cancer, and increased glycolysis is often observe... more Metabolic plasticity is an emerging hallmark of cancer, and increased glycolysis is often observed in transformed cells. Small molecule inhibitors that target driver oncogenes can potentially inhibit the glycolytic pathway. Osimertinib (AZD9291) is a novel EGFR tyrosine kinase inhibitor (TKI) that is potent and selective for sensitising (EGFRm) and T790M resistance mutations. Clinical studies have shown osimertinib to be efficacious in patients with EGFRm/ T790M advanced NSCLC who have progressed after EGFR-TKI treatment. However experience with targeted therapies suggests that acquired resistance may emerge. Thus there is a need to characterize resistance mechanisms and to devise ways to prevent, delay or overcome osimertinib resistance. We show here that osimertinib suppresses glycolysis in parental EGFR-mutant lung adenocarcinoma lines, but has not in osimertinib-resistant cell lines. Critically, we show osimertinib treatment induces a strict dependence on mitochondrial oxidative...
Differentiation of effector and memory CD8(+) T cells is accompanied by extensive changes in the ... more Differentiation of effector and memory CD8(+) T cells is accompanied by extensive changes in the transcriptome and histone modifications at gene promoters; however, the enhancer repertoire and associated gene regulatory networks are poorly defined. Using histone mark chromatin immunoprecipitation coupled with deep sequencing, we mapped the enhancer and super-enhancer landscapes in antigen-specific naive, differentiated effector, and central memory CD8(+) T cells during LCMV infection. Epigenomics-based annotation revealed a highly dynamic repertoire of enhancers, which were inherited, de novo activated, decommissioned and re-activated during CD8(+) T cell responses. We employed a computational algorithm to pair enhancers with target gene promoters. On average, each enhancer targeted three promoters and each promoter was regulated by two enhancers. By identifying enriched transcription factor motifs in enhancers, we defined transcriptional regulatory circuitry at each CD8(+) T cell r...
In this issue of Immunity, Gerlach et al. (2016) describe three distinct memory CD8(+) T cell sub... more In this issue of Immunity, Gerlach et al. (2016) describe three distinct memory CD8(+) T cell subsets based upon expression of the fractalkine receptor CX3CR1. Their findings revise the paradigm of effector and central memory T cells by revealing a subset of CD8(+) memory T cells defined by intermediate levels of expression of CX3CR1 that conducts tissue surveillance.
Quantification of the number of axons reinnervating a target organ is often used to assess regene... more Quantification of the number of axons reinnervating a target organ is often used to assess regeneration after peripheral nerve repair, but because of axonal branching, this method can overestimate the number of motor neurons regenerating across an injury. Current methods to count the number of regenerated motor neurons include retrograde labeling followed by cryosectioning and counting labeled motor neuron cell bodies, however, the process of sectioning introduces error from potential double counting of cells in adjacent sections. We describe a method, retroDISCO, that optically clears whole mouse spinal cord without loss of fluorescent signal to allow imaging of retrograde labeled motor neurons using confocal microscopy. Complete optical clearing of spinal cords takes four hours and confocal microscopy can obtain z-stacks of labeled motor neuron pools within 3-5minutes. The technique is able to detect anticipated differences in motor neuron number after cross-suture and conduit rep...
The efficacy and safety of proton pump inhibitors vs histamine-2 receptor antagonists for stress ... more The efficacy and safety of proton pump inhibitors vs histamine-2 receptor antagonists for stress ulcer bleeding prophylaxis among critical care patients: A meta-analysis.
Memory CD8 T-cell activation, including expression of IFN-γ and granzymeB, can be induced by anti... more Memory CD8 T-cell activation, including expression of IFN-γ and granzymeB, can be induced by antigen (Ag)-dependent signals through the T-cell-receptor, or by pathogen-derived inflammatory cytokines in an Ag-independent manner. Recent studies have come to conflicting results regarding the contributions of Ag and/or inflammation to memory CD8 T-cell activation. Additionally, research has indicated that inflammation-driven CD8 T-cell responses during un-related infections (bystander activation) have the potential to provide protection, but whether protection occurs in immuno-competent hosts is unclear. To investigate these questions, we examined activation of virus-specific memory CD8 T-cells following infection with L. monocytogenes either expressing or not cognate Ag. We show that Ag and inflammation act synergistically in vitro to induce memory activation. In vivo, we found that when memory CD8 T-cells significantly contribute to clearance of infection, early activation and continu...
Many organelles and vesicles in live cells move in a start-stop manner when observed for ~10 s by... more Many organelles and vesicles in live cells move in a start-stop manner when observed for ~10 s by optical microscopy. Changes in velocity and directional persistence of such particles are a potentially rich source of insight into the mechanisms leading to the start and stop states. Unbiased assessment of the most probable number of states, the properties of each state, and the most probable state for the particle at each moment can be accomplished by variational Bayesian methods combined with a hidden Markov model and a Gaussian mixture model. Our track analysis method, "vbTRACK", applied this combination of methods to particle velocity v or changes in the direction of travel evaluated from simulated tracks and from tracks of peroxisomes in live cells. When tested with numerical data, vbTRACK reliably determined the number of states, the mean and variance of the velocity or the direction of travel for each state, and the most probable state during each frame. When applied ...
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Papers by Matthew Martin