Showing papers in "Journal of Immunology in 2014"
TL;DR: The genetic modification of T cells with genes encoding αβ TCRs or chimeric Ag receptors and the administration of these cells after expansion in IL-2 have extended effective cell transfer therapy to other cancer types.
Abstract: The ability of IL-2 to expand T cells with maintenance of functional activity has been translated into the first reproducible effective human cancer immunotherapies. The administration of IL-2 can lead to durable, complete, and apparently curative regressions in patients with metastatic melanoma and renal cancer. The growth of large numbers of tumor-infiltrating lymphocytes with in vitro anti-cancer activity in IL-2 has led to the development of cell transfer therapies that are highly effective in patients with melanoma. The genetic modification of T cells with genes encoding αβ TCRs or chimeric Ag receptors and the administration of these cells after expansion in IL-2 have extended effective cell transfer therapy to other cancer types.
913 citations
Journal Article•
TL;DR: Results suggest that FcγR binding capacity by anti-HA antibodies was dependent on the interaction of the cognate Fab with antigen, a previously uncharacterized property of bNAbs, and guide an approach toward enhancing mAb-mediated antiviral therapeutics.
Abstract: Neutralizing antibodies (Abs) against influenza viruses have traditionally been thought to provide protection exclusively through their variable region; the contributions of mechanisms conferred by the Fc domain remain controversial We investigated the in vivo contributions of Fc interactions with their cognate receptors for a collection of neutralizing anti-influenza Abs Whereas five broadly neutralizing monoclonal Abs (bNAbs) targeting the conserved stalk region of hemagglutinin (HA) required interactions between the Ab Fc and Fcγ-receptors for IgG (FcγR) to confer protection from lethal H1N1 challenge, three strain-specific monoclonal Abs (mAbs) against the variable head domain of HA were equally protective in the presence or absence of FcγR interactions Although all Abs blocked infection, only anti-stalk bNAbs were able to mediate cytotoxicity of infected cells, which accounts for their FcγR dependence Immune complexes generated with anti-HA stalk mAb efficiently interacted with FcγRs, but anti-HA head immune complexes did not These results suggest that FcγR binding capacity by anti-HA Ab was dependent on the interaction of the cognate Fab with antigen We exploited these disparate mechanisms of mAb-mediated protection to reengineer an anti-stalk bNAb to selectively enhance FcγR engagement to augment its protective activity These findings reveal a previously uncharacterized property of bNAbs and guide an approach toward enhancing mAb-mediated anti-viral therapies
465 citations
TL;DR: Loss of FADD or caspase-8 in a RIP3-deficient background, but not RIP3 deficiency alone, hampered transcriptional priming and posttranslational activation of the canonical and noncanonical Nlrp3 inflammasome.
Abstract: The Nlrp3 inflammasome is critical for host immunity, but the mechanisms controlling its activation are enigmatic. In this study, we show that loss of FADD or caspase-8 in a RIP3-deficient background, but not RIP3 deficiency alone, hampered transcriptional priming and posttranslational activation of the canonical and noncanonical Nlrp3 inflammasome. Deletion of caspase-8 in the presence or absence of RIP3 inhibited caspase-1 and caspase-11 activation by Nlrp3 stimuli but not the Nlrc4 inflammasome. In addition, FADD deletion prevented caspase-8 maturation, positioning FADD upstream of caspase-8. Consequently, FADD- and caspase-8-deficient mice had impaired IL-1β production when challenged with LPS or infected with the enteropathogen Citrobacter rodentium. Thus, our results reveal FADD and caspase-8 as apical mediators of canonical and noncanonical Nlrp3 inflammasome priming and activation.
420 citations
TL;DR: Genetic association data support the conclusion that many of the immunologic and pathologic features of this disease are a consequence of a persistent self-directed immune reaction driven by IFN-I and mimicking a sustained antivirus response.
Abstract: Investigations of patients with systemic lupus erythematosus have applied insights from studies of the innate immune response to define IFN-I, with IFN-α as the dominant mediator, as central to the pathogenesis of this prototype systemic autoimmune disease. Genetic association data identify regulators of nucleic acid degradation and components of TLR-independent, endosomal TLR-dependent, and IFN-I-signaling pathways as contributors to lupus disease susceptibility. Together with a gene expression signature characterized by IFN-I-induced gene transcripts in lupus blood and tissue, those data support the conclusion that many of the immunologic and pathologic features of this disease are a consequence of a persistent self-directed immune reaction driven by IFN-I and mimicking a sustained antivirus response. This expanding knowledge of the role of IFN-I and the innate immune response suggests candidate therapeutic targets that are being tested in lupus patients.
411 citations
TL;DR: It is shown that SARS-CoV ORF-9b manipulates host cell mitochondria and mitochondrial function to help evade host innate immunity and illustrates the havoc that a small ORF can cause in cells.
Abstract: Coronaviruses (CoV) have recently emerged as potentially serious pathogens that can cause significant human morbidity and death. The severe acute respiratory syndrome (SARS)-CoV was identified as the etiologic agent of the 2002-2003 international SARS outbreak. Yet, how SARS evades innate immune responses to cause human disease remains poorly understood. In this study, we show that a protein encoded by SARS-CoV designated as open reading frame-9b (ORF-9b) localizes to mitochondria and causes mitochondrial elongation by triggering ubiquitination and proteasomal degradation of dynamin-like protein 1, a host protein involved in mitochondrial fission. Also, acting on mitochondria, ORF-9b targets the mitochondrial-associated adaptor molecule MAVS signalosome by usurping PCBP2 and the HECT domain E3 ligase AIP4 to trigger the degradation of MAVS, TRAF3, and TRAF 6. This severely limits host cell IFN responses. Reducing either PCBP2 or AIP4 expression substantially reversed the ORF-9b-mediated reduction of MAVS and the suppression of antiviral transcriptional responses. Finally, transient ORF-9b expression led to a strong induction of autophagy in cells. The induction of autophagy depended upon ATG5, a critical autophagy regulator, but the inhibition of MAVS signaling did not. These results indicate that SARS-CoV ORF-9b manipulates host cell mitochondria and mitochondrial function to help evade host innate immunity. This study has uncovered an important clue to the pathogenesis of SARS-CoV infection and illustrates the havoc that a small ORF can cause in cells.
391 citations
TL;DR: Testing the regulation and role of glucose uptake and metabolism in the proliferation and Ab production of control, anergic, and autoimmune-prone B cells shows that activated B cells require Glut1-dependent metabolic reprogramming to support proliferation andAb production that is distinct from T cells and that this glycolytic reprograming is regulated in tolerance.
Abstract: B cell activation leads to proliferation and Ab production that can protect from pathogens or promote autoimmunity. Regulation of cell metabolism is essential to support the demands of lymphocyte growth and effector function and may regulate tolerance. In this study, we tested the regulation and role of glucose uptake and metabolism in the proliferation and Ab production of control, anergic, and autoimmune-prone B cells. Control B cells had a balanced increase in lactate production and oxygen consumption following activation, with proportionally increased glucose transporter Glut1 expression and mitochondrial mass upon either LPS or BCR stimulation. This contrasted with metabolic reprogramming of T cells, which had lower glycolytic flux when resting but disproportionately increased this pathway upon activation. Importantly, tolerance greatly affected B cell metabolic reprogramming. Anergic B cells remained metabolically quiescent, with only a modest increase in glycolysis and oxygen consumption with LPS stimulation. B cells chronically stimulated with elevated BAFF, however, rapidly increased glycolysis and Ab production upon stimulation. Induction of glycolysis was critical for Ab production, as glycolytic inhibition with the pyruvate dehydrogenase kinase inhibitor dichloroacetate sharply suppressed B cell proliferation and Ab secretion in vitro and in vivo. Furthermore, B cell-specific deletion of Glut1 led to reduced B cell numbers and impaired Ab production in vivo. Together, these data show that activated B cells require Glut1-dependent metabolic reprogramming to support proliferation and Ab production that is distinct from T cells and that this glycolytic reprogramming is regulated in tolerance.
385 citations
TL;DR: The current literature on the Drosophila Imd pathway is reviewed, with special emphasis on its role in the (patho)physiology of different organs, and the systemic response, as well as local responses, in the epithelial and mucosal surfaces and the nervous system are discussed.
Abstract: The fruit fly, Drosophila melanogaster, has helped us to understand how innate immunity is activated. In addition to the Toll receptor and the Toll signaling pathway, the Drosophila immune response is regulated by another evolutionarily conserved signaling cascade, the immune deficiency (Imd) pathway, which activates NF-κB. In fact, the Imd pathway controls the expression of most of the antimicrobial peptides in Drosophila; thus, it is indispensable for normal immunity in flies. In this article, we review the current literature on the Drosophila Imd pathway, with special emphasis on its role in the (patho)physiology of different organs. We discuss the systemic response, as well as local responses, in the epithelial and mucosal surfaces and the nervous system.
383 citations
TL;DR: The results present a novel phenotypic, ontogenic, and molecular definition of liver-MF compartment following acute injury and show that infiltrating monocytes acquire a prorestorative polarization manifested by unique expression of proangiogenesis mediators and genes involved with inhibition of neutrophil activity and recruitment and promotion of their clearance.
Abstract: The liver has a remarkable capacity to regenerate after injury; yet, the role of macrophages (MF) in this process remains controversial mainly due to difficulties in distinguishing between different MF subsets. In this study, we used a murine model of acute liver injury induced by overdose of N- acetyl-p-aminophenol (APAP) and defined three distinct MF subsets that populate the liver following injury. Accordingly, resident Kupffer cells (KC) were significantly reduced upon APAP challenge and started recovering by self-renewal at resolution phase without contribution of circulating Ly6C hi monocytes. The latter were recruited in a CCR2- and M-CSF–mediated pathway at the necroinflammatory phase and differentiated into ephemeral Ly6C lo MF subset at resolution phase. Moreover, their inducible ablation resulted in impaired recovery. Microarray-based molecular profiling uncovered high similarity between steady-state KC and those recovered at the resolution phase. In contrast, KC and monocyte-derived MF displayed distinct prorestorative genetic signature at the resolution phase. Finally, we show that infiltrating monocytes acquire a prorestorative polarization manifested by unique expression of proangiogenesis mediators and genes involved with inhibition of neutrophil activity and recruitment and promotion of their clearance. Collectively, our results present a novel phenotypic, ontogenic, and molecular definition of liver-MF compartment following acute injury.
356 citations
TL;DR: The CCL2-CCR2 axis regulates macrophage polarization by influencing the expression of functionally relevant and polarization-associated genes and downmodulating proinflammatory cytokine production.
Abstract: The CCL2 chemokine mediates monocyte egress from bone marrow and recruitment into inflamed tissues through interaction with the CCR2 chemokine receptor, and its expression is upregulated by proinflammatory cytokines. Analysis of the gene expression profile in GM-CSF- and M-CSF-polarized macrophages revealed that a high CCL2 expression characterizes macrophages generated under the influence of M-CSF, whereas CCR2 is expressed only by GM-CSF-polarized macrophages. Analysis of the factors responsible for this differential expression identified activin A as a critical factor controlling the expression of the CCL2/CCR2 pair in macrophages, as activin A increased CCR2 expression but inhibited the acquisition of CCL2 expression by M-CSF-polarized macrophages. CCL2 and CCR2 were found to determine the extent of macrophage polarization because CCL2 enhances the LPS-induced production of IL-10, whereas CCL2 blockade leads to enhanced expression of M1 polarization-associated genes and cytokines, and diminished expression of M2-associated markers in human macrophages. Along the same line, Ccr2-deficient bone marrow-derived murine macrophages displayed an M1-skewed polarization profile at the transcriptomic level and exhibited a significantly higher expression of proinflammatory cytokines (TNF-α, IL-6) in response to LPS. Therefore, the CCL2-CCR2 axis regulates macrophage polarization by influencing the expression of functionally relevant and polarization-associated genes and downmodulating proinflammatory cytokine production.
345 citations
TL;DR: It is demonstrated that TCR β diversity per 106 T cells decreases roughly linearly with age, with significant reduction already apparent by age 40, and the percentage of naive T cells showed a strong correlation with measured TCR diversity and decreased linearly up to age 70.
Abstract: The decrease of TCR diversity with aging has never been studied by direct methods. In this study, we combined high-throughput Illumina sequencing with unique cDNA molecular identifier technology to achieve deep and precisely normalized profiling of TCR β repertoires in 39 healthy donors aged 6-90 y. We demonstrate that TCR β diversity per 10(6) T cells decreases roughly linearly with age, with significant reduction already apparent by age 40. The percentage of naive T cells showed a strong correlation with measured TCR diversity and decreased linearly up to age 70. Remarkably, the oldest group (average age 82 y) was characterized by a higher percentage of naive CD4(+) T cells, lower abundance of expanded clones, and increased TCR diversity compared with the previous age group (average age 62 y), suggesting the influence of age selection and association of these three related parameters with longevity. Interestingly, cross-analysis of individual TCR β repertoires revealed a set >10,000 of the most representative public TCR β clonotypes, whose abundance among the top 100,000 clones correlated with TCR diversity and decreased with aging.
341 citations
TL;DR: The data reveal that NK cells undergo dramatic metabolic reprogramming upon activation, upregulating rates of glucose uptake and glycolysis, and that mTORC1 activity is essential for attaining this elevatedglycolytic state.
Abstract: The mammalian target of rapamycin complex 1 (mTORC1) is a key regulator of cellular metabolism and also has fundamental roles in controlling immune responses. Emerging evidence suggests that these two functions of mTORC1 are integrally linked. However, little is known regarding mTORC1 function in controlling the metabolism and function of NK cells, lymphocytes that play key roles in antiviral and antitumor immunity. This study investigated the hypothesis that mTORC1-controlled metabolism underpins normal NK cell proinflammatory function. We demonstrate that mTORC1 is robustly stimulated in NK cells activated in vivo and in vitro. This mTORC1 activity is required for the production of the key NK cell effector molecules IFN-γ, which is important in delivering antimicrobial and immunoregulatory functions, and granzyme B, a critical component of NK cell cytotoxic granules. The data reveal that NK cells undergo dramatic metabolic reprogramming upon activation, upregulating rates of glucose uptake and glycolysis, and that mTORC1 activity is essential for attaining this elevated glycolytic state. Directly limiting the rate of glycolysis is sufficient to inhibit IFN-γ production and granzyme B expression. This study provides the highly novel insight that mTORC1-mediated metabolic reprogramming of NK cells is a prerequisite for the acquisition of normal effector functions.
TL;DR: The generated RIP1 kinase-dead mice are viable and healthy, indicating that the kinase activity of RIP1, but not its scaffolding function, is dispensable for viability and homeostasis, and suggest that RIP 1 kinase represents an attractive therapeutic target for TNF-driven inflammatory diseases.
Abstract: RIP1 (RIPK1) kinase is a key regulator of TNF-induced NF-κB activation, apoptosis, and necroptosis through its kinase and scaffolding activities. Dissecting the balance of RIP1 kinase activity and scaffolding function in vivo during development and TNF-dependent inflammation has been hampered by the perinatal lethality of RIP1-deficient mice. In this study, we generated RIP1 kinase-dead (Ripk1(K45A)) mice and showed they are viable and healthy, indicating that the kinase activity of RIP1, but not its scaffolding function, is dispensable for viability and homeostasis. After validating that the Ripk1(K45A) mice were specifically protected against necroptotic stimuli in vitro and in vivo, we crossed them with SHARPIN-deficient cpdm mice, which develop severe skin and multiorgan inflammation that has been hypothesized to be mediated by TNF-dependent apoptosis and/or necroptosis. Remarkably, crossing Ripk1(K45A) mice with the cpdm strain protected against all cpdm-related pathology. Together, these data suggest that RIP1 kinase represents an attractive therapeutic target for TNF-driven inflammatory diseases.
TL;DR: The data suggest that epidermal TRM cells are retained in resolved Psoriasis and that these cells are capable of producing cytokines with a critical role in psoriasis pathogenesis, and provide a potential mechanism for a site-specific T cell–driven disease memory in psOriasis.
Abstract: Psoriasis is a common and chronic inflammatory skin disease in which T cells play a key role. Effective treatment heals the skin without scarring, but typically psoriasis recurs in previously affected areas. A pathogenic memory within the skin has been proposed, but the nature of such site-specific disease memory is unknown. Tissue-resident memory T (TRM) cells have been ascribed a role in immunity after resolved viral skin infections. Because of their localization in the epidermal compartment of the skin, TRM may contribute to tissue pathology during psoriasis. In this study, we investigated whether resolved psoriasis lesions contain TRM cells with the ability to maintain and potentially drive recurrent disease. Three common and effective therapies, narrowband-UVB treatment and long-term biologic treatment systemically inhibiting TNF-α or IL-12/23 signaling were studied. Epidermal T cells were highly activated in psoriasis and a high proportion of CD8 T cells expressed TRM markers. In resolved psoriasis, a population of cutaneous lymphocyte–associated Ag, CCR6, CD103, and IL-23R expressing epidermal CD8 T cells was highly enriched. Epidermal CD8 T cells expressing the TRM marker CD103 responded to ex vivo stimulation with IL-17A production and epidermal CD4 T cells responded with IL-22 production after as long as 6 y of TNF-α inhibition. Our data suggest that epidermal TRM cells are retained in resolved psoriasis and that these cells are capable of producing cytokines with a critical role in psoriasis pathogenesis. We provide a potential mechanism for a site-specific T cell–driven disease memory in psoriasis.
TL;DR: It is found that aging correlated strictly to an absolute loss of naive CD8, but not CD4, T cells but, contrary to many reports, did not lead to an increase in memory T cell numbers, suggesting that efficacy of viral control over time may determine the magnitude of CMV impact upon T cell memory, and perhaps upon immune defense.
Abstract: The impact of intrinsic aging upon human peripheral blood T cell subsets remains incompletely quantified and understood. This impact must be distinguished from the influence of latent persistent microorganisms, particularly CMV, which has been associated with age-related changes in the T cell pool. In a cross-sectional cohort of 152 CMV-negative individuals, aged 21-101 y, we found that aging correlated strictly to an absolute loss of naive CD8, but not CD4, T cells but, contrary to many reports, did not lead to an increase in memory T cell numbers. The loss of naive CD8 T cells was not altered by CMV in 239 subjects (range 21-96 y), but the decline in CD4(+) naive cells showed significance in CMV(+) individuals. These individuals also exhibited an absolute increase in the effector/effector memory CD4(+) and CD8(+) cells with age. That increase was seen mainly, if not exclusively, in older subjects with elevated anti-CMV Ab titers, suggesting that efficacy of viral control over time may determine the magnitude of CMV impact upon T cell memory, and perhaps upon immune defense. These findings provide important new insights into the age-related changes in the peripheral blood pool of older adults, demonstrating that aging and CMV exert both distinct and joint influence upon blood T cell homeostasis in humans.
TL;DR: It is shown in this study that lineage-negative ST2+ICOS+CD45+ type 2 ILCs and CD4+ T cells can potently stimulate each other’s function via distinct mechanisms.
Abstract: CD4(+) T cells have long been grouped into distinct helper subsets on the basis of their cytokine-secretion profile. In recent years, several subsets of innate lymphoid cell have been described as key producers of these same Th-associated cytokines. However, the functional relationship between Th cells and innate lymphoid cells (ILCs) remains unclear. We show in this study that lineage-negative ST2(+)ICOS(+)CD45(+) type 2 ILCs and CD4(+) T cells can potently stimulate each other's function via distinct mechanisms. CD4(+) T cell provision of IL-2 stimulates type 2 cytokine production by type 2 ILCs. By contrast, type 2 ILCs modulate naive T cell activation in a cell contact-dependent manner, favoring Th2 while suppressing Th1 differentiation. Furthermore, a proportion of type 2 ILCs express MHC class II and can present peptide Ag in vitro. Importantly, cotransfer experiments show that type 2 ILCs also can boost CD4(+) T cell responses to Ag in vivo.
Journal Article•
TL;DR: The pRESTO toolkit supports multiplexed primer pools, single- or paired-end reads and emerging technologies that use single-molecule identifiers, and has a built-in capacity to parallelize the work between available processors and is able to efficiently process millions of sequences generated by typical high-throughput projects.
Abstract: Summary: Driven by dramatic technological improvements, large-scale characterization of lymphocyte receptor repertoires via high-throughput sequencing is now feasible. Although promising, the high germline and somatic diversity, especially of B-cell immunoglobulin repertoires, presents challenges for analysis requiring the development of specialized computational pipelines. We developed the REpertoire Sequencing TOolkit (pRESTO) for processing reads from high-throughput lymphocyte receptor studies. pRESTO processes raw sequences to produce error-corrected, sorted and annotated sequence sets, along with a wealth of metrics at each step. The toolkit supports multiplexed primer pools, single- or paired-end reads, and emerging technologies that employ single-molecule barcodes. pRESTO has been tested on data generated from Roche and Illumina platforms. It has a built in capacity to parallelize the work between available processors, and is able to efficiently process millions of sequences generated by typical high-throughput projects. As part of ongoing collaborations, pRESTO has been applied to multiple B-cell repertoire studies, employing both Roche 454 and Illumina MiSeq sequencing technologies. Availability: pRESTO is freely available for academic use. The software package and detailed tutorials may be downloaded from http://clip.med.yale.edu/pRESTO.
TL;DR: It is shown that control of M. tuberculosis correlates with the ability of CD4 T cells to efficiently enter the lung parenchyma rather than produce high levels of IFN-γ.
Abstract: Th1 cells are critical for containment of Mycobacterium tuberculosis infection, but little else is known about the properties of protective CD4 T cell responses. In this study, we show that the pulmonary Th1 response against M. tuberculosis is composed of two populations that are either CXCR3(hi) and localize to lung parenchyma or are CX3CR1(hi)KLRG1(hi) and are retained within lung blood vasculature. M. tuberculosis-specific parenchymal CD4 T cells migrate rapidly back into the lung parenchyma upon adoptive transfer, whereas the intravascular effectors produce the highest levels of IFN-γ in vivo. Importantly, parenchymal T cells displayed greater control of infection compared with the intravascular counterparts upon transfer into susceptible T cell-deficient hosts. Thus, we identified a subset of naturally generated M. tuberculosis-specific CD4 T cells with enhanced protective capacity and showed that control of M. tuberculosis correlates with the ability of CD4 T cells to efficiently enter the lung parenchyma rather than produce high levels of IFN-γ.
TL;DR: Genetic evidence is provided that the kinase activity of RIPK1 is not required for survival but is essential for TNF-, TRIF-, and viral-initiated necroptosis.
Abstract: The serine/threonine kinase RIPK1 is recruited to TNFR1 to mediate proinflammatory signaling and to regulate TNF-induced cell death. A RIPK1 deficiency results in perinatal lethality, impaired NFκB and MAPK signaling, and sensitivity to TNF-induced apoptosis. Chemical inhibitor and in vitro-reconstitution studies suggested that RIPK1 displays distinct kinase activity-dependent and -independent functions. To determine the contribution of RIPK1 kinase to inflammation in vivo, we generated knock-in mice endogenously expressing catalytically inactive RIPK1 D138N. Unlike Ripk1(-/-) mice, which die shortly after birth, Ripk1(D138N/D138N) mice are viable. Cells expressing RIPK1 D138N are resistant to TNF- and polyinosinic-polycytidylic acid-induced necroptosis in vitro, and Ripk1(D138N/D138N) mice are protected from TNF-induced shock in vivo. Moreover, Ripk1(D138N/D138N) mice fail to control vaccinia virus replication in vivo. This study provides genetic evidence that the kinase activity of RIPK1 is not required for survival but is essential for TNF-, TRIF-, and viral-initiated necroptosis.
TL;DR: Elevated macrophage miR-21 promotes efferocytosis and silences target genes PTEN and PDCD4, which in turn accounts for a net anti-inflammatory phenotype, which highlights the significance of miRs in the resolution of wound inflammation.
Abstract: At an injury site, efficient clearance of apoptotic cells by wound macrophages or efferocytosis is a prerequisite for the timely resolution of inflammation. Emerging evidence indicates that microRNA-21 (miR-21) may regulate the inflammatory response. In this work, we sought to elucidate the significance of miR-21 in the regulation of efferocytosis-mediated suppression of innate immune response, a key process implicated in resolving inflammation following injury. An increased expression of inducible miR-21 was noted in postefferocytotic peripheral blood monocyte-derived macrophages. Such induction of miR-21 was associated with silencing of its target genes PTEN and PDCD4. Successful efferocytosis of apoptotic cells by monocyte-derived macrophages resulted in the suppression of LPS-induced NF-κB activation and TNF-α expression. Interestingly, bolstering of miR-21 levels alone, using miR mimic, resulted in significant suppression of LPS-induced TNF-α expression and NF-κB activation. We report that efferocytosis-induced miR-21, by silencing PTEN and GSK3β, tempers the LPS-induced inflammatory response. Macrophage efferocytosis is known to trigger the release of anti-inflammatory cytokine IL-10. This study demonstrates that following successful efferocytosis, miR-21 induction in macrophages silences PDCD4, favoring c-Jun-AP-1 activity, which in turn results in elevated production of anti-inflammatory IL-10. In summary, this work provides direct evidence implicating miRNA in the process of turning on an anti-inflammatory phenotype in the postefferocytotic macrophage. Elevated macrophage miR-21 promotes efferocytosis and silences target genes PTEN and PDCD4, which in turn accounts for a net anti-inflammatory phenotype. Findings of this study highlight the significance of miRs in the resolution of wound inflammation.
TL;DR: Findings suggest novel targets for treatment of ALI, for which there is currently no known efficacious drug, and an interaction between extracellular histones and the NLRP3 inflammasome, resulting in ALI.
Abstract: The inflammasome is a key factor in innate immunity and senses soluble pathogen and danger-associated molecular patterns as well as biological crystals (urate, cholesterol, etc.), resulting in expression of IL-1β and IL-18. Using a standard model of acute lung injury (ALI) in mice featuring airway instillation of LPS, ALI was dependent on availability of NLRP3 as well as caspase-1, which are known features of the NLRP3 inflammasome. The appearance of IL-1β, a product of NLRP3 inflammasome activation, was detected in bronchoalveolar lavage fluids (BALF) in a macrophage- and neutrophil-dependent manner. Neutrophil-derived extracellular histones appeared in the BALF during ALI and directly activated the NLRP3 inflammasome. Ab-mediated neutralization of histones significantly reduced IL-1β levels in BALF during ALI. Inflammasome activation by extracellular histones in LPS-primed macrophages required NLRP3 and caspase-1 as well as extrusion of K+, increased intracellular Ca2+ concentration, and generation of reactive oxygen species. NLRP3 and caspase-1 were also required for full extracellular histone presence during ALI, suggesting a positive feedback mechanism. Extracellular histone and IL-1β levels in BALF were also elevated in C5a-induced and IgG immune complex ALI models, suggesting a common inflammatory mechanism. These data indicate an interaction between extracellular histones and the NLRP3 inflammasome, resulting in ALI. Such findings suggest novel targets for treatment of ALI, for which there is currently no known efficacious drug.
TL;DR: IL-36 cytokines actively propagate skin inflammation via the activation of keratinocytes, APC, and, indirectly, T cells as well as stimulating the maturation and function of DC and drive T cell proliferation.
Abstract: The IL-1 family members IL-36α (IL-1F6), IL-36β (IL-1F8), and IL-36γ (IL-1F9) and the receptor antagonist IL-36Ra (IL-1F5) constitute a novel signaling system that is poorly understood. We now show that these cytokines have profound effects on the skin immune system. Treatment of human keratinocytes with IL-36 cytokines significantly increased the expression of CXCL1, CXCL8, CCL3, CCL5, and CCL20, potent chemotactic agents for activated leukocytes, and IL-36α injected intradermally resulted in chemokine expression, leukocyte infiltration, and acanthosis of mouse skin. Blood monocytes, myeloid dendritic cells (mDC), and monocyte-derived DC (MO-DC) expressed IL-36R and responded to IL-36. In contrast, no direct effects of IL-36 on resting or activated human CD4 + or CD8 + T cells, or blood neutrophils, could be demonstrated. Monocytes expressed IL-1A, IL-1B, and IL-6 mRNA and IL-1β and IL-6 protein, and mDC upregulated surface expression of CD83, CD86, and HLA-DR and secretion of IL-1β and IL-6 after treatment with IL-36. Furthermore, IL-36α–treated MO-DC enhanced allogeneic CD4 + T cell proliferation, demonstrating that IL-36 can stimulate the maturation and function of DC and drive T cell proliferation. These data indicate that IL-36 cytokines actively propagate skin inflammation via the activation of keratinocytes, APC, and, indirectly, T cells.
TL;DR: It is identified that basophils and ILC2s significantly accumulate in inflamed human and murine skin and form clusters not observed in control skin, and a previously unrecognized role for basophil-derived IL-4 in promoting I LC2 responses during cutaneous inflammation is revealed.
Abstract: Type 2 inflammation underlies allergic diseases such as atopic dermatitis, which is characterized by the accumulation of basophils and group 2 innate lymphoid cells (ILC2s) in inflamed skin lesions Although murine studies have demonstrated that cutaneous basophil and ILC2 responses are dependent on thymic stromal lymphopoietin, whether these cell populations interact to regulate the development of cutaneous type 2 inflammation is poorly defined In this study, we identify that basophils and ILC2s significantly accumulate in inflamed human and murine skin and form clusters not observed in control skin We demonstrate that murine basophil responses precede ILC2 responses and that basophils are the dominant IL-4-enhanced GFP-expressing cell type in inflamed skin Furthermore, basophils and IL-4 were necessary for the optimal accumulation of ILC2s and induction of atopic dermatitis-like disease We show that ILC2s express IL-4Rα and proliferate in an IL-4-dependent manner Additionally, basophil-derived IL-4 was required for cutaneous ILC2 responses in vivo and directly regulated ILC2 proliferation ex vivo Collectively, these data reveal a previously unrecognized role for basophil-derived IL-4 in promoting ILC2 responses during cutaneous inflammation
TL;DR: A review of mechanisms by which Dendritic cell-derived exosomes interact with and influence immune cells and describes how they can be engineered to promote their immunogenic capacity as novel and dynamic anticancer agents.
Abstract: Exosomes are nanometric membrane vesicles of late endosomal origin released by most, if not all, cell types as a means of sophisticated intercellular communication. A multitude of studies showed how exosomes can mediate and regulate immune responses against tumors. Dendritic cell–derived exosomes (Dex) have received much attention as immunotherapeutic anticancer agents since the discovery that they harbor functional MHC–peptide complexes, in addition to various other immune-stimulating components, that together facilitate immune cell–dependent tumor rejection. The therapeutic potential of Dex has been substantiated with their development and clinical testing in the treatment of cancer. This review focuses on mechanisms by which Dex interact with and influence immune cells and describes how they can be engineered to promote their immunogenic capacity as novel and dynamic anticancer agents.
Journal Article•
TL;DR: It is shown that the GC response undergoes a temporal switch in its output as it matures, revealing that the reaction engenders both MBC subsets with different immune effector function and, ultimately, LLPCs at largely separate points in time.
Abstract: Though memory B cells (MBCs) and long-lived plasma cells (LLPCs) are both thought to derive from the germinal center (GC) reaction, there is little insight into or agreement about the signals that control differentiation to one cell type or another. By performing BrdU pulse-labeling studies, GC disruption experiments and V gene sequencing, we found that the generation of these cell types is actually temporally controlled and separated during the immune response. We report that MBCs mainly derive from early GCs (much before GC peak size), while more affinity matured LLPCs are predominantly formed during late GCs - long after its peak in size. Based on these findings, we propose a new model that the GC response undergoes a temporal switch, functioning quite differently at early and late stages. Therefore the generation of MBCs and LLPCs is the consequence of a general shift in GC output over time rather than the result of specific instructive signals that are selectively delivered to GC B cells at any given time during the response. We also present direct evidence that a large fraction of long-lived IgM+ MBC, and even some IgG+ MBC, are formed at very early time points, prior to the existence of detectable GCs. The knowledge of when specific long-lived immune-effector cells are generated during an immune response has strong implications for vaccine design and understanding long-term pathogen immunity.
TL;DR: It is concluded that CC employ the complement system to induce cytokines and activate the inflammasome/caspase-1 by regulating several cellular responses in human monocytes, and complement inhibition might be an interesting therapeutic approach for treatment of atherosclerosis.
Abstract: Inflammation is associated with development of atherosclerosis, and cholesterol crystals (CC) have long been recognized as a hallmark of atherosclerotic lesions. CC appear early in the atheroma development and trigger inflammation by NLRP3 inflammasome activation. In this study we hypothesized whether CC employ the complement system to activate inflammasome/caspase-1, leading to release of mature IL-1β, and whether complement activation regulates CC-induced cytokine production. In this study we describe that CC activated both the classical and alternative complement pathways, and C1q was found to be crucial for the activation. CC employed C5a in the release of a number of cytokines in whole blood, including IL-1β and TNF. CC induced minimal amounts of cytokines in C5-deficient whole blood, until reconstituted with C5. Furthermore, C5a and TNF in combination acted as a potent primer for CC-induced IL-1β release by increasing IL-1β transcripts. CC-induced complement activation resulted in upregulation of complement receptor 3 (CD11b/CD18), leading to phagocytosis of CC. Also, CC mounted a complement-dependent production of reactive oxygen species and active caspase-1. We conclude that CC employ the complement system to induce cytokines and activate the inflammasome/caspase-1 by regulating several cellular responses in human monocytes. In light of this, complement inhibition might be an interesting therapeutic approach for treatment of atherosclerosis.
TL;DR: It is demonstrated that the production of sIL-6Rα from macrophages in the diseased lung contributes to IL-6 trans signaling that in turn influences events crucial in pulmonary fibrosis.
Abstract: Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease with progressive fibrosis and death within 2–3 y of diagnosis. IPF incidence and prevalence rates are increasing annually with few effective treatments available. Inhibition of IL-6 results in the attenuation of pulmonary fibrosis in mice. It is unclear whether this is due to blockade of classical signaling, mediated by membrane-bound IL-6Rα, or trans signaling, mediated by soluble IL-6Rα (sIL-6Rα). Our study assessed the role of sIL-6Rα in IPF. We demonstrated elevations of sIL-6Rα in IPF patients and in mice during the onset and progression of fibrosis. We demonstrated that protease-mediated cleavage from lung macrophages was important in production of sIL-6Rα. In vivo neutralization of sIL-6Rα attenuated pulmonary fibrosis in mice as seen by reductions in myofibroblasts, fibronectin, and collagen in the lung. In vitro activation of IL-6 trans signaling enhanced fibroblast proliferation and extracellular matrix protein production, effects relevant in the progression of pulmonary fibrosis. Taken together, these findings demonstrate that the production of sIL-6Rα from macrophages in the diseased lung contributes to IL-6 trans signaling that in turn influences events crucial in pulmonary fibrosis.
TL;DR: It is demonstrated that knocking out the DNA sensor cyclic GMP–AMP synthase completely abrogates spontaneous induction of IFN-stimulated genes in TREX1-deficient cells, indicating a key role of cyclicGMP–amp synthase for the initiation of self-DNA–induced autoimmune disorders, thus providing important implications for novel therapeutic approaches.
Abstract: Cytosolic detection of DNA is crucial for the initiation of antiviral immunity but can also cause autoimmunity in the context of endogenous nucleic acids being sensed. Mutations in the human 3' repair exonuclease 1 (TREX1) have been linked to the type I IFN-associated autoimmune disease Aicardi-Goutieres syndrome. The exact mechanisms driving unabated type I IFN responses in the absence of TREX1 are only partly understood, but it appears likely that accumulation of endogenous DNA species triggers a cell-autonomous immune response by activating a cytosolic DNA receptor. In this article, we demonstrate that knocking out the DNA sensor cyclic GMP-AMP synthase completely abrogates spontaneous induction of IFN-stimulated genes in TREX1-deficient cells. These findings indicate a key role of cyclic GMP-AMP synthase for the initiation of self-DNA-induced autoimmune disorders, thus providing important implications for novel therapeutic approaches.
TL;DR: The results reveal a new immunosuppressive property of IFN-γ–licensed MSCs that inhibits T cell effector function independent of IDO but through the ligands for PD1.
Abstract: Human bone marrow-derived mesenchymal stromal cells (MSCs) inhibit proliferation of activated T cells, and IFN-γ plays an important role in this process. This IFN-γ-licensed veto property is IDO-dependent. To further decipher the mechanistic underpinnings of MSC veto function on T cells, we investigated the effect of MSCs and IFN-γ-licensed MSCs on T cell effector function as assayed by cytokine secretion of T cells. Although MSCs and IFN-γ-licensed MSCs inhibit T cell proliferation, only IFN-γ-licensed MSCs significantly inhibit Th1 cytokine (IFN-γ, TNF-α, and IL-2) production by T cells. Additionally, IFN-γ-licensed MSCs inhibit T cell degranulation as well as single, double, and triple cytokine-producing T cells. Although IFN-γ-licensed MSCs upregulate their IDO activity, we found that MSC IDO catalytic function is dispensable with regard to MSC-driven inhibition of T cell effector function. Novel flow cytometry based functional screening of MSC-expressed, IFN-γ-licensed inhibitory molecules identified B7H1 and B7DC/PD1 pathways as essential effectors in blocking T cell function. Small interfering RNA-mediated blocking of B7H1 and B7DC reverses the inhibitory potential of IFN-γ-licensed MSCs on T cell effector function. Mechanistic analysis revealed that clustering of MHC and coinhibitory molecules are indispensable for the inhibitory effect of IFN-γ MSCs. Although exogenous IL-2 reverses B7H1-Ig-mediated inhibition of T cell proliferation, it does not affect the veto function of IFN-γ MSCs on both T cell proliferation and effector function. Our results reveal a new immunosuppressive property of IFN-γ-licensed MSCs that inhibits T cell effector function independent of IDO but through the ligands for PD1.
TL;DR: This article introduces the various stages of mouse thymocyte development and highlights recent work using various in vivo and in vitro models of T cell development that led to discoveries in the regulation afforded by transcription factors and receptor–ligand signaling pathways in specifying, maintaining, and promoting the T cell lineage and the production of T cells.
Abstract: The generation of a functional and diverse repertoire of T cells occurs in the thymus from precursors arriving from the bone marrow. In this article, we introduce the various stages of mouse thymocyte development and highlight recent work using various in vivo, and, where appropriate, in vitro models of T cell development that led to discoveries in the regulation afforded by transcription factors and receptor-ligand signaling pathways in specifying, maintaining, and promoting the T cell lineage and the production of T cells. This review also discusses the role of the thymic microenvironment in providing a niche for the successful development of T cells. In particular, we focus on advances in Notch signaling and developments in Notch ligand interactions in this process.
TL;DR: Several aspects of CSR are discussed, including how CSR is induced, CSR in B cell progenitors, the roles of transcription and chromosomal looping in CSR, and the role of certain DNA-repair enzymes inCSR.
Abstract: IgH class switching occurs rapidly after activation of mature naive B cells, resulting in a switch from expression of IgM and IgD to expression of IgG, IgE, or IgA; this switch improves the ability of Abs to remove the pathogen that induces the humoral immune response. Class switching occurs by a deletional recombination between two switch regions, each of which is associated with a H chain constant region gene. Class switch recombination (CSR) is instigated by activation-induced cytidine deaminase, which converts cytosines in switch regions to uracils. The uracils are subsequently removed by two DNA-repair pathways, resulting in mutations, single-strand DNA breaks, and the double-strand breaks required for CSR. We discuss several aspects of CSR, including how CSR is induced, CSR in B cell progenitors, the roles of transcription and chromosomal looping in CSR, and the roles of certain DNA-repair enzymes in CSR.