CCR2 enhances CD25 expression by FoxP3+ regulatory T cells and regulates their abundance independently of chemotaxis and CCR2+ myeloid cells

A wide array of chemokine receptors, including CCR2, are known to control Treg migration. Here, we report that CCR2 regulates Tregs beyond chemotaxis. We found that CCR2 deficiency reduced CD25 expression by FoxP3⁺ Treg cells. Such a change was also consistently present in irradiation chimeras reconstituted with mixed bone marrow from wild-type (WT) and CCR2-/- strains. Thus, CCR2 deficiency resulted in profound loss of CD25^hi FoxP3⁺ Tregs in secondary lymphoid organs as well as in peripheral tissues. CCR2-/- Treg cells were also functionally inferior to WT cells. Interestingly, these changes to Treg cells did not depend on CCR2⁺ monocytes/moDCs (the cells where CCR2 receptors are most abundant). Rather, we demonstrated that CCR2 was required for TLR-stimulated, but not TCR- or IL-2-stimulated, CD25 upregulation on Treg cells. Thus, we propose that CCR2 signaling can increase the fitness of FoxP3⁺ Treg cells and provide negative feedback to counter the proinflammatory effects of CCR2 on myeloid cells.

MAIT cells contribute to protection against lethal influenza infection in vivo

Mucosal associated invariant T (MAIT) cells are evolutionarily-conserved, innate-like lymphocytes which are abundant in human lungs and can contribute to protection against pulmonary bacterial infection. MAIT cells are also activated during human viral infections, yet it remains unknown whether MAIT cells play a significant protective or even detrimental role during viral infections in vivo. Using murine experimental challenge with two strains of influenza A virus, we show that MAIT cells accumulate and are activated early in infection, with upregulation of CD25, CD69 and Granzyme B, peaking at 5 days post-infection. Activation is modulated via cytokines independently of MR1. MAIT cell-deficient MR1-/- mice show enhanced weight loss and mortality to severe (H1N1) influenza. This is ameliorated by prior adoptive transfer of pulmonary MAIT cells in both immunocompetent and immunodeficient RAG2-/-γC-/- mice. Thus, MAIT cells contribute to protection during respiratory viral infections, and constitute a potential target for therapeutic manipulation.

The Role of BACH2 in T Cells in Experimental Malaria Caused by Plasmodium chabaudi chabaudi AS

BTB and CNC Homology 1, Basic Leucine Zipper Transcription Factor 2 (BACH2) is a transcription factor best known for its role in B cell development. More recently, it has been associated with T cell functions in inflammatory diseases, and has been proposed as a master transcriptional regulator within the T cell compartment. In this study, we employed T cell-specific Bach2-deficient (B6.Bach2^ΔT) mice to examine the role of this transcription factor in CD4⁺ T cell functions in vitro and in mice infected with Plasmodium chabaudi AS. We found that under CD4⁺ T cell polarizing conditions in vitro, Th2, and Th17 helper cell subsets were more active in the absence of Bach2 expression. In mice infected with P. chabaudi AS, although the absence of Bach2 expression by T cells had no effect on blood parasitemia or disease pathology, we found reduced expansion of CD4⁺ T cells in B6.Bach2^ΔT mice, compared with littermate controls. Despite this reduction, we observed increased frequencies of Tbet⁺ IFNγ⁺ CD4⁺ (Th1) cells and IL-10-producing Th1 (Tr1) cells in mice lacking Bach2 expression by T cells. Studies in mixed bone marrow chimeric mice revealed T cell intrinsic effects of BACH2 on hematopoietic cell development, and in particular, the generation of CD4⁺ and CD8⁺ T cell subsets. Furthermore, T cell intrinsic BACH2 was needed for efficient expansion of CD4⁺ T cells during experimental malaria in this immunological setting. We also examined the response of B6.Bach2^ΔT mice to a second protozoan parasitic challenge with Leishmania donovani and found similar effects on disease outcome and T cell responses. Together, our findings provide new insights into the role of BACH2 in CD4⁺ T cell activation during experimental malaria, and highlight an important role for this transcription factor in the development and expansion of T cells under homeostatic conditions, as well as establishing the composition of the effector CD4⁺ T cell compartment during infection.

A new species of Aschistophleps from Thailand and Laos, with a new generic synonymy (Lepidoptera, Sesiidae)

We here describe a new clearwing moth species, Aschistophleps ignisquamulata sp. nov., from northern Thailand and Laos. This striking new species differs from all other species of Osminiini in both external appearance and genitalia and displays characteristics that indicate that Pyrophleps Arita Gorbunov is a junior subjective synonym of Aschistophleps (syn. nov.).

A new zygaenid moth species from Kangaroo Island, South Australia (Lepidoptera: Zygaenidae: Procridinae)

A new species of forester moths, Pollanisus hyacinthus sp. nov., is described from Kangaroo Island, South Australia. It is similar to Pollanisus isolatus Tarmann, 2004 and Pollanisus cyanota (Meyrick, 1886) but differs in several external characters and in the genitalia.

Follicular B Cells Promote Atherosclerosis via T Cell–Mediated Differentiation Into Plasma Cells and Secreting Pathogenic Immunoglobulin G

Objective—

B cells promote or protect development of atherosclerosis. In this study, we examined the role of MHCII (major histocompatibility II), CD40 (cluster of differentiation 40), and Blimp-1 (B-lymphocyte–induced maturation protein) expression by follicular B (FO B) cells in development of atherosclerosis together with the effects of IgG purified from atherosclerotic mice.

Approach and Results—

Using mixed chimeric Ldlr −/− mice whose B cells are deficient in MHCII or CD40, we demonstrate that these molecules are critical for the proatherogenic actions of FO B cells. During development of atherosclerosis, these deficiencies affected T–B cell interactions, germinal center B cells, plasma cells, and IgG. As FO B cells differentiating into plasma cells require Blimp-1, we also assessed its role in the development of atherosclerosis. Blimp-1-deficient B cells greatly attenuated atherosclerosis and immunoglobulin—including IgG production, preventing IgG accumulation in atherosclerotic lesions; Blimp-1 deletion also attenuated lesion proinflammatory cytokines, apoptotic cell numbers, and necrotic core. To determine the importance of IgG for atherosclerosis, we purified IgG from atherosclerotic mice. Their transfer but not IgG from nonatherosclerotic mice into Ldlr −/− mice whose B cells are Blimp-1-deficient increased atherosclerosis; transfer was associated with IgG accumulating in atherosclerotic lesions, increased lesion inflammatory cytokines, apoptotic cell numbers, and necrotic core size.

Conclusions—

The mechanism by which FO B cells promote atherosclerosis is highly dependent on their expression of MHCII, CD40, and Blimp-1. FO B cell differentiation into IgG-producing plasma cells also is critical for their proatherogenic actions. Targeting B–T cell interactions and pathogenic IgG may provide novel therapeutic strategies to prevent atherosclerosis and its adverse cardiovascular complications.

Cord Blood CD8+ T Cells Have a Natural Propensity to Express IL-4 in a Fatty Acid Metabolism and Caspase Activation-Dependent Manner

How T cells differentiate in the neonate may critically determine the ability of the infant to cope with infections, respond to vaccines and avert allergies. Previously, we found that naïve cord blood CD4⁺ T cells differentiated toward an IL-4-expressing phenotype when activated in the presence of TGF-β and monocyte-derived inflammatory cytokines, the latter are more highly secreted by infants who developed food allergy. Here, we show that in the absence of IL-2 or IL-12, naïve cord blood CD8⁺ T cells have a natural propensity to differentiate into IL-4-producing non-classic T_C2 cells when they are activated alone, or in the presence of TGF-β and/or inflammatory cytokines. Mechanistically, non-classic T_C2 development is associated with decreased expression of IL-2 receptor alpha (CD25) and glycolysis, and increased fatty acid metabolism and caspase-dependent cell death. Consequently, the short chain fatty acid, sodium propionate (NaPo), enhanced IL-4 expression, but exogenous IL-2 or pan-caspase inhibition prevented IL-4 expression. In children with endoscopically and histologically confirmed non-inflammatory bowel disease and non-infectious pediatric idiopathic colitis, the presence of TGF-β, NaPo, and IL-1β or TNF-α promoted T_C2 differentiation in vitro. In vivo, colonic mucosa of children with colitis had significantly increased expression of IL-4 in CD8⁺ T cells compared with controls. In addition, activated caspase-3 and IL-4 were co-expressed in CD8⁺ T cells in the colonic mucosa of children with colitis. Thus, in the context of colonic inflammation and limited IL-2 signaling, CD8⁺ T cells differentiate into non-classic T_C2 that may contribute to the pathology of inflammatory/allergic diseases in children.

A new sun moth species from the Flinders Ranges in South Australia (Lepidoptera, Castniidae)

Sun moths (Castniidae) constitute a small family of day-flying butterfly-like moths that have their centers of diversity in South America and Australia. Here we describe a new castniid from the Finders Ranges, South Australia. Synemon arkaroola spec. nov. is similar and related to Synemon brontias Meyrick, 1891 but differs by a number of external and genitalic characters, including the extensive bright orange markings on the hindwings. The new species inhabits dry creek beds and adjacent slopes where the hostplant, Scented Lemon Grass, Cymbopogon ambiguus (Hack.) A. Camus (Poaceae), grows.

Identifying low-grade cellular rejection after heart transplantation in children by using gene expression profiling

Endomyocardial biopsy (EMB) remains the gold standard for detecting rejection after heart transplantation but is costly and invasive. This study aims to distinguish no rejection (0R) from low-grade rejection (1R/2R) after heart transplantation in children by using global gene expression profiling in blood. A total of 106 blood samples with corresponding EMB from 18 children who underwent heart transplantation from 2011 to 2014 were analyzed (18 baseline/pretransplantation samples, 88 EMB samples). Corresponding rejection grades for each blood sample were 0R in 39% (34/88), 1R in 51% (45/88), and 2R in 10% (9/88). mRNA from each sample was sequenced. Differential expression analysis was performed at the gene level. A k-nearest neighbor (kNN) analysis was applied to the most differentially expressed (DE) genes to identify rejection after transplantation. Mean age at transplantation was 10.0 ± 5.4 yr. Expression of B cell and T cell receptor sequences was used to measure the effect of posttransplantation immunosuppression. Follow-up samples had lower levels of immunoglobulin gene families compared with pretransplantation ( P < 3E-5) (lower numbers of activated B cells). T cell receptor alpha and beta gene families had decreased expression in 0R samples compared with pretransplantation ( P < 4E-5) but recovered to near baseline levels in 1R/2R samples. kNN using the most DE gene (MKS1) and k = 9 nearest neighbors correctly identified 83% (73/88) of 1R/2R compared with 0R by leave-one-out cross validation. Using a genomic approach we can distinguish low-grade cellular allograft rejection (1R/2R) from no rejection (0R) after heart transplantation in children despite a wide age range.

Transcription Factor IRF4 Promotes CD8+ T Cell Exhaustion and Limits the Development of Memory-like T Cells during Chronic Infection

During chronic stimulation, CD8⁺ T cells acquire an exhausted phenotype characterized by expression of inhibitory receptors, down-modulation of effector function, and metabolic impairments. T cell exhaustion protects from excessive immunopathology but limits clearance of virus-infected or tumor cells. We transcriptionally profiled antigen-specific T cells from mice infected with lymphocytic choriomeningitis virus strains that cause acute or chronic disease. T cell exhaustion during chronic infection was driven by high amounts of T cell receptor (TCR)-induced transcription factors IRF4, BATF, and NFATc1. These regulators promoted expression of inhibitory receptors, including PD-1, and mediated impaired cellular metabolism. Furthermore, they repressed the expression of TCF1, a transcription factor required for memory T cell differentiation. Reducing IRF4 expression restored the functional and metabolic properties of antigen-specific T cells and promoted memory-like T cell development. These findings indicate that IRF4 functions as a central node in a TCR-responsive transcriptional circuit that establishes and sustains T cell exhaustion during chronic infection.

A preliminary molecular phylogeny of shield-bearer moths (Lepidoptera: Adeloidea: Heliozelidae) highlights rich undescribed diversity

Heliozelidae are a widespread, evolutionarily early diverging family of small, day-flying monotrysian moths, for which a comprehensive phylogeny is lacking. We generated the first molecular phylogeny of the family using DNA sequences of two mitochondrial genes (COI and COII) and two nuclear genes (H3 and 28S) from 130 Heliozelidae specimens, including eight of the twelve known genera: Antispila, Antispilina, Coptodisca, Heliozela, Holocacista, Hoplophanes, Pseliastis, and Tyriozela. Our results provide strong support for five major Heliozelidae clades: (i) a large widespread clade containing the leaf-mining genera Antispilina, Coptodisca and Holocacista and some species of Antispila, (ii) a clade containing most of the described Antispila, (iii) a clade containing the leaf-mining genus Heliozela and the monotypic genus Tyriozela, (iv) an Australian clade containing Pseliastis and (v) an Australian clade containing Hoplophanes. Each clade includes several new species and potentially new genera. Collectively, our data uncover a rich and undescribed diversity that appears to be especially prevalent in Australia. Our work highlights the need for a major taxonomic revision of the family and for generating a robust molecular phylogeny using multi-gene approaches in order to resolve the relationships among clades.

Local Modulation of Antigen-Presenting Cell Development after Resolution of Pneumonia Induces Long-Term Susceptibility to Secondary Infections

Lung infections cause prolonged immune alterations and elevated susceptibility to secondary pneumonia. We found that, after resolution of primary viral or bacterial pneumonia, dendritic cells (DC), and macrophages exhibited poor antigen-presentation capacity and secretion of immunogenic cytokines. Development of these "paralyzed" DCs and macrophages depended on the immunosuppressive microenvironment established upon resolution of primary infection, which involved regulatory T (Treg) cells and the cytokine TGF-β. Paralyzed DCs secreted TGF-β and induced local Treg cell accumulation. They also expressed lower amounts of IRF4, a transcription factor associated with increased antigen-presentation capacity, and higher amounts of Blimp1, a transcription factor associated with tolerogenic functions, than DCs present during primary infection. Blimp1 expression in DC of humans suffering sepsis or trauma correlated with severity and complicated outcomes. Our findings describe mechanisms underlying sepsis- and trauma-induced immunosuppression, reveal prognostic markers of susceptibility to secondary infections and identify potential targets for therapeutic intervention.

The TNF Receptor Superfamily-NF-κB Axis Is Critical to Maintain Effector Regulatory T Cells in Lymphoid and Non-lymphoid Tissues

After exiting the thymus, Foxp3⁺ regulatory T (Treg) cells undergo further differentiation in the periphery, resulting in the generation of mature, fully suppressive effector (e)Treg cells in a process dependent on TCR signaling and the transcription factor IRF4. Here, we show that tumor necrosis factor receptor superfamily (TNFRSF) signaling plays a crucial role in the development and maintenance of eTreg cells. TNFRSF signaling activated the NF-κB transcription factor RelA, which was required to maintain eTreg cells in lymphoid and non-lymphoid tissues, including RORγt⁺ Treg cells in the small intestine. In response to TNFRSF signaling, RelA regulated basic cellular processes, including cell survival and proliferation, but was dispensable for IRF4 expression or DNA binding, indicating that both pathways operated independently. Importantly, mutations in the RelA binding partner NF-κB1 compromised eTreg cells in humans, suggesting that the TNFRSF-NF-κB axis was required in a non-redundant manner to maintain eTreg cells in mice and humans.

Sugars and fat - A healthy way to generate functional regulatory T cells

Cellular metabolism has emerged as an important regulator of adaptive immunity. While the metabolic requirements of conventional T cells are increasingly understood, the role of cellular metabolism in Foxp3⁺ regulatory T (Treg) cells is less clear. Although it is well accepted that repression of Akt/mTOR, HIF-1α and aerobic glycolysis are important for the efficient generation of Treg cells in vitro, clear evidence how these pathways impact on Treg-cell development in vivo is limited. Furthermore, newer studies have shown that the same pathways that appear to suppress Treg-cell development are active in and required for functionally mature Treg cells. Thus, it becomes increasingly evident that development and function of regulatory T cells require different wiring of metabolic pathways. Finally, it is likely that critical differences remain to be uncovered between the metabolism of resting or 'naïve' Treg cells and those fully differentiated and actively engaged in suppression. In this comment, we briefly discuss our current understanding of Treg-cell metabolism and the need to address this area with new approaches based on in vivo models.

Distinct mechanisms govern resident memory T cell differentiation and survival in different tissues

Tissue-resident memory T (Trm) cells are a recently defined population of memory T cells that persist at the site of previous infection and contribute to protective local immunity. Trm cells have been identified in both epithelial and solid organs; however, despite their ubiquity, they share molecular commonalities that are distinct from circulating memory T cells. Therefore, we sought to explore the transcriptional regulation of Trm cells in a number of different organs. Our earlier data demonstrated that Trm cells share a core transcriptional signature regulated by the two related transcription factors Hobit and Blimp1. Here we show that Trm cells also have distinct molecular requirements according to anatomic location. While Hobit was uniquely required for the development of Trm cells in all organs tested, Blimp1 was required in some organs, but dispensable in others. Similar to Blimp1, the T-box transcription factor T-bet was also required for Trm cell development in only a subset of organs. This differential transcription factor dependency was linked to distinct cytokine requirements for Trm cell development in different organs. Trm cell defects were enhanced in the absence of multiple transcription factors, suggesting functional redundancy and implicating a role for distinct transcriptional networks as drivers of Trm cell development in different organs. Together, these data demonstrate the adaptation of Trm cells to specific tissue microenvironments and highlight the importance of studying these cells in a variety of organs.

Eomesodermin promotes the development of type 1 regulatory T (TR1) cells

Type 1 regulatory T (T_R1) cells are Foxp3^- interleukin-10 (IL-10)-producing CD4⁺ T cells with potent immunosuppressive properties, but their requirements for lineage development have remained elusive. We show that T_R1 cells constitute the most abundant regulatory population after allogeneic bone marrow transplantation (BMT), express the transcription factor Eomesodermin (Eomes), and are critical for the prevention of graft-versus-host disease. We demonstrate that Eomes is required for T_R1 cell differentiation, during which it acts in concert with the transcription factor B lymphocyte-induced maturation protein-1 (Blimp-1) by transcriptionally activating IL-10 expression and repressing differentiation into other T helper cell lineages. We further show that Eomes induction in T_R1 cells requires T-bet and donor macrophage-derived IL-27. Thus, we define the cellular and transcriptional control of T_R1 cell differentiation during BMT, opening new avenues to therapeutic manipulation.

Transcription Factor T-bet Orchestrates Lineage Development and Function in the Immune System

T-bet was originally described as the key transcription factor defining type 1 T helper (Th) cells. However, it is now clear that it drives the orchestrated generation of effector and memory cells in multiple different lymphocyte lineages. In addition to Th1 cells, CD8 T cells, B cells and some innate lymphocyte populations require T-bet for their development or differentiation in response to antigen. Furthermore, other Th cell populations, including T follicular helper and Th17, as well as regulatory T cells can co-opt T-bet expression to promote functional diversification and colocalization. Thus, T-bet broadly regulates transcriptional programs in response to type 1 inflammatory signals and mediates the coordinated differentiation, function, migration and survival of effector and memory lymphocyte subsets in the affected tissue. Therefore, T-bet expression is essential for effective clearance of pathogens and maintenance of immunity.

A non-canonical function of Ezh2 preserves immune homeostasis

Enhancer of zeste 2 (Ezh2) mainly methylates lysine 27 of histone-H3 (H3K27me3) as part of the polycomb repressive complex 2 (PRC2) together with Suz12 and Eed. However, Ezh2 can also modify non-histone substrates, although it is unclear whether this mechanism has a role during development. Here, we present evidence for a chromatin-independent role of Ezh2 during T-cell development and immune homeostasis. T-cell-specific depletion of Ezh2 induces a pronounced expansion of natural killer T (NKT) cells, although Ezh2-deficient T cells maintain normal levels of H3K27me3. In contrast, removal of Suz12 or Eed destabilizes canonical PRC2 function and ablates NKT cell development completely. We further show that Ezh2 directly methylates the NKT cell lineage defining transcription factor PLZF, leading to its ubiquitination and subsequent degradation. Sustained PLZF expression in Ezh2-deficient mice is associated with the expansion of a subset of NKT cells that cause immune perturbation. Taken together, we have identified a chromatin-independent function of Ezh2 that impacts on the development of the immune system.

The BCL-2 pro-survival protein A1 is dispensable for T cell homeostasis on viral infection

The physiological role of the pro-survival BCL-2 family member A1 has been debated for a long time. Strong mRNA induction in T cells on T cell receptor (TCR)-engagement suggested a major role of A1 in the survival of activated T cells. However, the investigation of the physiological roles of A1 was complicated by the quadruplication of the A1 gene locus in mice, making A1 gene targeting very difficult. Here, we used the recently generated A1^-/- mouse model to examine the role of A1 in T cell immunity. We confirmed rapid and strong induction of A1 protein in response to TCR/CD3 stimulation in CD4⁺ as well as CD8⁺ T cells. Surprisingly, on infection with the acute influenza HKx31 or the lymphocytic choriomeningitis virus docile strains mice lacking A1 did not show any impairment in the expansion, survival, or effector function of cytotoxic T cells. Furthermore, the ability of A1^-/- mice to generate antigen-specific memory T cells or to provide adequate CD4-dependent help to B cells was not impaired. These results suggest functional redundancy of A1 with other pro-survival BCL-2 family members in the control of T cell-dependent immune responses.

A new species and new records of Melittiini from China and Vietnam (Lepidoptera, Sesiidae)

We review the Melittiini fauna of mainland China and list a total of 14 species in two genera. Melittia proxima Le Cerf, 1917, Melittia fulvipes Kallies & Arita, 2004, Melittia distincta Le Cerf, 1916, and Macroscelesia vietnamica Arita & Gorbunov, 2000 are recorded from China for the first time. Macroscelesia perlucida Kallies & Arita, sp. nov. is described as new to science based on specimens collected in China (Guangxi Province) and in northern Vietnam. Melittia formosana Matsumura, 1911 is considered a subspecies of Melittia eurytion (Westwood, 1848) (stat. nov.), and Melittia eurytion nagaii Arita & Gorbunov, 1997 is treated as a junior subjective synonym of M. eurytion formosana (syn. nov.).