All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
We examined the role of innate cells in acquired resistance to the natural murine parasitic nemat... more We examined the role of innate cells in acquired resistance to the natural murine parasitic nematode, Nippostrongylus brasiliensis. Macrophages obtained from lungs as late as 45 d after N. brasiliensis inoculation were able to transfer accelerated parasite clearance to naive recipients. Primed macrophages adhered to larvae in vitro and triggered increased mortality of parasites. Neutrophil depletion in primed mice abrogated the protective effects of transferred macrophages and inhibited their in vitro binding to larvae. Neutrophils in parasite-infected mice showed a distinct transcriptional profile and promoted alternatively activated M2 macrophage polarization through secretory factors including IL-13. Differentially activated neutrophils in the context of a type 2 immune response therefore prime a long-lived effector macrophage phenotype that directly mediates rapid nematode damage and clearance.
Mechanisms responsible for pulmonary tissue homeostasis and regeneration are incompletely underst... more Mechanisms responsible for pulmonary tissue homeostasis and regeneration are incompletely understood. This study investigated whether Trefoil factor family (TFF) proteins, regulators of gastrointestinal restitution, served any role in the pulmonary tract under steady state conditions or pathogen infection. At baseline, TFF2 lung mRNA transcript levels were highest compared to TFF1 and TFF3. Strikingly, TFF2 deficient mice (TFF2-/-) were hypoxic by 6-8 weeks of age, with abnormal alveoli, reduced blood oxygen levels, and defective integrin expression on alveolar type 1 cells. TFF2 was essential for mucosal barrier function in tracheal epithelia and TFF2 deficiency caused multiple transcriptional defects in adhesion, motility, and wound repair. Unexpectedly, TFF2 expression in hematopoietic cells was necessary for Type 2 immunity and recovery of pulmonary function after inoculation with the hookworm Nippostrongylus brasiliensis. TFF2 served a cell-intrinsic role in promoting macrophag...
Malaria, caused by Plasmodium sp. parasites, is a leading cause of global morbidity and mortality... more Malaria, caused by Plasmodium sp. parasites, is a leading cause of global morbidity and mortality. Cerebral malaria, characterized by neurological symptoms, is a life-threatening complication of malaria affecting over 500,000 young children in Africa every year. Because of the prevalence and severity of cerebral malaria, a better understanding of the underlying molecular mechanisms of its pathology is desirable and could inform future development of therapeutics. This study sought to clarify the role of Toll-like receptors (TLRs) in promoting immunopathology associated with cerebral malaria, with a particular focus on the understudied TLR7. Using the Plasmodium berghei ANKA mouse model of experimental cerebral malaria, C57BL/6 mice deficient in various TLRs were infected, and their resistance to cerebral malaria and immune activation through cytokine production were measured. Loss of TLR7 conferred partial protection against fatal experimental cerebral malaria. Additionally, loss of...
Innate γδ T cells function in the early phase of immune responses. Although innate γδ T cells hav... more Innate γδ T cells function in the early phase of immune responses. Although innate γδ T cells have often been studied as one homogenous population, they can be functionally classified into effector subsets on the basis of the production of signature cytokines, analogous to adaptive helper T cell subsets. However, unlike the function of adaptive T cells, γδ effector T cell function correlates with genomically encoded T cell antigen receptor (TCR) chains, which suggests that clonal TCR selection is not the main determinant of the differentiation of γδ effector cells. A high-resolution transcriptome analysis of all emergent γδ thymocyte subsets segregated on the basis of use of the TCR γ-chain or δ-chain indicated the existence of three separate subtypes of γδ effector cells in the thymus. The immature γδ subsets were distinguished by unique transcription-factor modules that program effector function.
ABSTRACTInnate immune recognition of malaria parasites is the critical first step in the developm... more ABSTRACTInnate immune recognition of malaria parasites is the critical first step in the development of the host response. At present, Toll-like receptor 9 (TLR9) is thought to play a central role in sensing malaria infection. However, we and others have observed thatTlr9−/−mice, in contrast to mice deficient in the downstream adaptor, Myeloid differentiation primary response gene 88 (MYD88), exhibit few deficiencies in immune function during early infection with the malaria parasitePlasmodium chabaudi, implying that another MYD88-dependent receptor also contributes to the antimalarial response. Here we use candidate-based screening to identify TLR7 as a key sensor of earlyP. chabaudiinfection. We show that TLR7 mediates a rapid systemic response to infection through induction of cytokines such as type I interferons (IFN-I), interleukin 12, and gamma interferon. TLR7 is also required for induction of IFN-I by other species and strains ofPlasmodium, including an etiological agent of ...
HAN MLJ JOOSTEN,1* MANUEL NUN˜EZ,1 BART DEVREESE,2 JOZEF VAN BEEUMEN,2 AND JOEY D. MARUGG3 Depart... more HAN MLJ JOOSTEN,1* MANUEL NUN˜EZ,1 BART DEVREESE,2 JOZEF VAN BEEUMEN,2 AND JOEY D. MARUGG3 Departamento de Tecnologıa de Alimentos, CIT-INIA, 28040 Madrid, Spain1; Vakgroep Biochemie, Fysiologie en Microbiologie, Universiteit Gent, 9000 Ghent, ...
Mouse models have demonstrated utility in delineating the mechanisms underlying many aspects of m... more Mouse models have demonstrated utility in delineating the mechanisms underlying many aspects of malaria immunology and physiology. The most common mouse models of malaria employ the rodent-specific parasite species Plasmodium berghei, P. yoelii, and P. chabaudi, which elicit distinct pathologies and immune responses and are used to model different manifestations of human disease. In vitro culture methods are not well developed for rodent Plasmodium parasites, which thus require in vivo maintenance. Moreover, physiologically relevant immunological processes are best studied in vivo. Here, we detail the processes of infecting mice with Plasmodium, maintaining the parasite in vivo, and monitoring parasite levels and health parameters throughout infection.
As animals grow, many early born structures grow by cell expansion rather than cell addition; thu... more As animals grow, many early born structures grow by cell expansion rather than cell addition; thus growth of distinct structures must be coordinated to maintain proportionality. This phenomenon is particularly widespread in the nervous system, with dendrite arbors of many neurons expanding in concert with their substrate to sustain connectivity and maintain receptive field coverage as animals grow. After rapidly growing to establish body wall coverage, dendrites of Drosophila class IV dendrite arborization (C4da) neurons grow synchronously with their substrate, the body wall epithelium, providing a system to study how proportionality is maintained during animal growth. Here, we show that the microRNA bantam (ban) ensures coordinated growth of C4da dendrites and the epithelium through regulation of epithelial endoreplication, a modified cell cycle that entails genome amplification without cell division. In Drosophila larvae, epithelial endoreplication leads to progressive changes in ...
Journal of immunology (Baltimore, Md. : 1950), 2015
Activated macrophages are crucial for restriction of microbial infection but may also promote inf... more Activated macrophages are crucial for restriction of microbial infection but may also promote inflammatory pathology in a wide range of both infectious and sterile conditions. The pathways that regulate macrophage activation are therefore of great interest. Recent studies in silico have putatively identified key transcription factors that may control macrophage activation, but experimental validation is lacking. In this study, we generated a macrophage regulatory network from publicly available microarray data, employing steps to enrich for physiologically relevant interactions. Our analysis predicted a novel relationship between the AP-1 family transcription factor Junb and the gene Il1b, encoding the pyrogen IL-1β, which macrophages express upon activation by inflammatory stimuli. Previously, Junb has been characterized primarily as a negative regulator of the cell cycle, whereas AP-1 activity in myeloid inflammatory responses has largely been attributed to c-Jun. We confirmed exp...
Although clinical immunity to malaria eventually develops among children living in endemic settin... more Although clinical immunity to malaria eventually develops among children living in endemic settings, the underlying immunologic mechanisms are not known. The Vδ2(+) subset of γδ T cells have intrinsic reactivity to malaria antigens, can mediate killing of Plasmodium falciparum merozoites, and expand markedly in vivo after malaria infection in previously naïve hosts, but their role in mediating immunity in children repeatedly exposed to malaria is unclear. We evaluated γδ T cell responses to malaria among 4-year-old children enrolled in a longitudinal study in Uganda. We found that repeated malaria was associated with reduced percentages of Vδ2(+) γδ T cells in peripheral blood, decreased proliferation and cytokine production in response to malaria antigens, and increased expression of immunoregulatory genes. Further, loss and dysfunction of proinflammatory Vδ2(+) γδ T cells were associated with a reduced likelihood of symptoms upon subsequent P. falciparum infection. Together, these results suggest that repeated malaria infection during childhood results in progressive loss and dysfunction of Vδ2(+) γδ T cells that may facilitate immunological tolerance of the parasite.
The manual counting of cells by microscopy is a commonly used technique across biological discipl... more The manual counting of cells by microscopy is a commonly used technique across biological disciplines. Traditionally, hand tally counters have been used to track event counts. Although this method is adequate, there are a number of inefficiencies which arise when managing large numbers of samples or large sample sizes. We describe software that mimics a traditional multi-register tally counter. Full customizability allows operation on any computer with minimal hardware requirements. The efficiency of counting large numbers of samples and/or large sample sizes is improved through the use of a "multi-count" register that allows single keystrokes to correspond to multiple events. Automatically updated multi-parameter values are implemented as user-specified equations, reducing errors and time required for manual calculations. The user interface was optimized for use with a touch screen and numeric keypad, eliminating the need for a full keyboard and mouse. Our software provides an inexpensive, flexible, and productivity-enhancing alternative to manual hand tally counters.
Whereas genome sequencing has given us high-resolution pictures of many different species of bact... more Whereas genome sequencing has given us high-resolution pictures of many different species of bacteria, microarrays provide a means of obtaining information on genome composition for many strains of a given species. Genome-composition analysis using microarrays, or 'genomotyping', can be used to categorize genes into 'present' and 'divergent' categories based on the level of hybridization signal. This typically involves selecting a signal value that is used as a cutoff to discriminate present (high signal) and divergent (low signal) genes. Current methodology uses empirical determination of cutoffs for classification into these categories, but this methodology is subject to several problems that can result in the misclassification of many genes. We describe a method that depends on the shape of the signal-ratio distribution and does not require empirical determination of a cutoff. Moreover, the cutoff is determined on an array-to-array basis, accounting for va...
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
We examined the role of innate cells in acquired resistance to the natural murine parasitic nemat... more We examined the role of innate cells in acquired resistance to the natural murine parasitic nematode, Nippostrongylus brasiliensis. Macrophages obtained from lungs as late as 45 d after N. brasiliensis inoculation were able to transfer accelerated parasite clearance to naive recipients. Primed macrophages adhered to larvae in vitro and triggered increased mortality of parasites. Neutrophil depletion in primed mice abrogated the protective effects of transferred macrophages and inhibited their in vitro binding to larvae. Neutrophils in parasite-infected mice showed a distinct transcriptional profile and promoted alternatively activated M2 macrophage polarization through secretory factors including IL-13. Differentially activated neutrophils in the context of a type 2 immune response therefore prime a long-lived effector macrophage phenotype that directly mediates rapid nematode damage and clearance.
Mechanisms responsible for pulmonary tissue homeostasis and regeneration are incompletely underst... more Mechanisms responsible for pulmonary tissue homeostasis and regeneration are incompletely understood. This study investigated whether Trefoil factor family (TFF) proteins, regulators of gastrointestinal restitution, served any role in the pulmonary tract under steady state conditions or pathogen infection. At baseline, TFF2 lung mRNA transcript levels were highest compared to TFF1 and TFF3. Strikingly, TFF2 deficient mice (TFF2-/-) were hypoxic by 6-8 weeks of age, with abnormal alveoli, reduced blood oxygen levels, and defective integrin expression on alveolar type 1 cells. TFF2 was essential for mucosal barrier function in tracheal epithelia and TFF2 deficiency caused multiple transcriptional defects in adhesion, motility, and wound repair. Unexpectedly, TFF2 expression in hematopoietic cells was necessary for Type 2 immunity and recovery of pulmonary function after inoculation with the hookworm Nippostrongylus brasiliensis. TFF2 served a cell-intrinsic role in promoting macrophag...
Malaria, caused by Plasmodium sp. parasites, is a leading cause of global morbidity and mortality... more Malaria, caused by Plasmodium sp. parasites, is a leading cause of global morbidity and mortality. Cerebral malaria, characterized by neurological symptoms, is a life-threatening complication of malaria affecting over 500,000 young children in Africa every year. Because of the prevalence and severity of cerebral malaria, a better understanding of the underlying molecular mechanisms of its pathology is desirable and could inform future development of therapeutics. This study sought to clarify the role of Toll-like receptors (TLRs) in promoting immunopathology associated with cerebral malaria, with a particular focus on the understudied TLR7. Using the Plasmodium berghei ANKA mouse model of experimental cerebral malaria, C57BL/6 mice deficient in various TLRs were infected, and their resistance to cerebral malaria and immune activation through cytokine production were measured. Loss of TLR7 conferred partial protection against fatal experimental cerebral malaria. Additionally, loss of...
Innate γδ T cells function in the early phase of immune responses. Although innate γδ T cells hav... more Innate γδ T cells function in the early phase of immune responses. Although innate γδ T cells have often been studied as one homogenous population, they can be functionally classified into effector subsets on the basis of the production of signature cytokines, analogous to adaptive helper T cell subsets. However, unlike the function of adaptive T cells, γδ effector T cell function correlates with genomically encoded T cell antigen receptor (TCR) chains, which suggests that clonal TCR selection is not the main determinant of the differentiation of γδ effector cells. A high-resolution transcriptome analysis of all emergent γδ thymocyte subsets segregated on the basis of use of the TCR γ-chain or δ-chain indicated the existence of three separate subtypes of γδ effector cells in the thymus. The immature γδ subsets were distinguished by unique transcription-factor modules that program effector function.
ABSTRACTInnate immune recognition of malaria parasites is the critical first step in the developm... more ABSTRACTInnate immune recognition of malaria parasites is the critical first step in the development of the host response. At present, Toll-like receptor 9 (TLR9) is thought to play a central role in sensing malaria infection. However, we and others have observed thatTlr9−/−mice, in contrast to mice deficient in the downstream adaptor, Myeloid differentiation primary response gene 88 (MYD88), exhibit few deficiencies in immune function during early infection with the malaria parasitePlasmodium chabaudi, implying that another MYD88-dependent receptor also contributes to the antimalarial response. Here we use candidate-based screening to identify TLR7 as a key sensor of earlyP. chabaudiinfection. We show that TLR7 mediates a rapid systemic response to infection through induction of cytokines such as type I interferons (IFN-I), interleukin 12, and gamma interferon. TLR7 is also required for induction of IFN-I by other species and strains ofPlasmodium, including an etiological agent of ...
HAN MLJ JOOSTEN,1* MANUEL NUN˜EZ,1 BART DEVREESE,2 JOZEF VAN BEEUMEN,2 AND JOEY D. MARUGG3 Depart... more HAN MLJ JOOSTEN,1* MANUEL NUN˜EZ,1 BART DEVREESE,2 JOZEF VAN BEEUMEN,2 AND JOEY D. MARUGG3 Departamento de Tecnologıa de Alimentos, CIT-INIA, 28040 Madrid, Spain1; Vakgroep Biochemie, Fysiologie en Microbiologie, Universiteit Gent, 9000 Ghent, ...
Mouse models have demonstrated utility in delineating the mechanisms underlying many aspects of m... more Mouse models have demonstrated utility in delineating the mechanisms underlying many aspects of malaria immunology and physiology. The most common mouse models of malaria employ the rodent-specific parasite species Plasmodium berghei, P. yoelii, and P. chabaudi, which elicit distinct pathologies and immune responses and are used to model different manifestations of human disease. In vitro culture methods are not well developed for rodent Plasmodium parasites, which thus require in vivo maintenance. Moreover, physiologically relevant immunological processes are best studied in vivo. Here, we detail the processes of infecting mice with Plasmodium, maintaining the parasite in vivo, and monitoring parasite levels and health parameters throughout infection.
As animals grow, many early born structures grow by cell expansion rather than cell addition; thu... more As animals grow, many early born structures grow by cell expansion rather than cell addition; thus growth of distinct structures must be coordinated to maintain proportionality. This phenomenon is particularly widespread in the nervous system, with dendrite arbors of many neurons expanding in concert with their substrate to sustain connectivity and maintain receptive field coverage as animals grow. After rapidly growing to establish body wall coverage, dendrites of Drosophila class IV dendrite arborization (C4da) neurons grow synchronously with their substrate, the body wall epithelium, providing a system to study how proportionality is maintained during animal growth. Here, we show that the microRNA bantam (ban) ensures coordinated growth of C4da dendrites and the epithelium through regulation of epithelial endoreplication, a modified cell cycle that entails genome amplification without cell division. In Drosophila larvae, epithelial endoreplication leads to progressive changes in ...
Journal of immunology (Baltimore, Md. : 1950), 2015
Activated macrophages are crucial for restriction of microbial infection but may also promote inf... more Activated macrophages are crucial for restriction of microbial infection but may also promote inflammatory pathology in a wide range of both infectious and sterile conditions. The pathways that regulate macrophage activation are therefore of great interest. Recent studies in silico have putatively identified key transcription factors that may control macrophage activation, but experimental validation is lacking. In this study, we generated a macrophage regulatory network from publicly available microarray data, employing steps to enrich for physiologically relevant interactions. Our analysis predicted a novel relationship between the AP-1 family transcription factor Junb and the gene Il1b, encoding the pyrogen IL-1β, which macrophages express upon activation by inflammatory stimuli. Previously, Junb has been characterized primarily as a negative regulator of the cell cycle, whereas AP-1 activity in myeloid inflammatory responses has largely been attributed to c-Jun. We confirmed exp...
Although clinical immunity to malaria eventually develops among children living in endemic settin... more Although clinical immunity to malaria eventually develops among children living in endemic settings, the underlying immunologic mechanisms are not known. The Vδ2(+) subset of γδ T cells have intrinsic reactivity to malaria antigens, can mediate killing of Plasmodium falciparum merozoites, and expand markedly in vivo after malaria infection in previously naïve hosts, but their role in mediating immunity in children repeatedly exposed to malaria is unclear. We evaluated γδ T cell responses to malaria among 4-year-old children enrolled in a longitudinal study in Uganda. We found that repeated malaria was associated with reduced percentages of Vδ2(+) γδ T cells in peripheral blood, decreased proliferation and cytokine production in response to malaria antigens, and increased expression of immunoregulatory genes. Further, loss and dysfunction of proinflammatory Vδ2(+) γδ T cells were associated with a reduced likelihood of symptoms upon subsequent P. falciparum infection. Together, these results suggest that repeated malaria infection during childhood results in progressive loss and dysfunction of Vδ2(+) γδ T cells that may facilitate immunological tolerance of the parasite.
The manual counting of cells by microscopy is a commonly used technique across biological discipl... more The manual counting of cells by microscopy is a commonly used technique across biological disciplines. Traditionally, hand tally counters have been used to track event counts. Although this method is adequate, there are a number of inefficiencies which arise when managing large numbers of samples or large sample sizes. We describe software that mimics a traditional multi-register tally counter. Full customizability allows operation on any computer with minimal hardware requirements. The efficiency of counting large numbers of samples and/or large sample sizes is improved through the use of a "multi-count" register that allows single keystrokes to correspond to multiple events. Automatically updated multi-parameter values are implemented as user-specified equations, reducing errors and time required for manual calculations. The user interface was optimized for use with a touch screen and numeric keypad, eliminating the need for a full keyboard and mouse. Our software provides an inexpensive, flexible, and productivity-enhancing alternative to manual hand tally counters.
Whereas genome sequencing has given us high-resolution pictures of many different species of bact... more Whereas genome sequencing has given us high-resolution pictures of many different species of bacteria, microarrays provide a means of obtaining information on genome composition for many strains of a given species. Genome-composition analysis using microarrays, or 'genomotyping', can be used to categorize genes into 'present' and 'divergent' categories based on the level of hybridization signal. This typically involves selecting a signal value that is used as a cutoff to discriminate present (high signal) and divergent (low signal) genes. Current methodology uses empirical determination of cutoffs for classification into these categories, but this methodology is subject to several problems that can result in the misclassification of many genes. We describe a method that depends on the shape of the signal-ratio distribution and does not require empirical determination of a cutoff. Moreover, the cutoff is determined on an array-to-array basis, accounting for va...
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