Effector and central memory T helper 2 cells respond differently to peptide immunotherapy.
ABSTRACT: Peptide immunotherapy (PIT) offers realistic prospects for the treatment of allergic diseases, including allergic asthma. Much is understood of the behavior of naive T cells in response to PIT. However, treatment of patients with ongoing allergic disease requires detailed understanding of the responses of allergen-experienced T cells. CD62L expression by allergen-experienced T cells corresponds to effector/effector memory (CD62L(lo)) and central memory (CD62L(hi)) subsets, which vary with allergen exposure (e.g., during, or out with, pollen season). The efficacy of PIT on different T helper 2 (Th2) cell memory populations is unknown. We developed a murine model of PIT in allergic airway inflammation (AAI) driven by adoptively transferred, traceable ovalbumin-experienced Th2 cells. PIT effectively suppressed AAI driven by unfractionated Th2 cells. Selective transfer of CD62L(hi) and CD62L(lo) Th2 cells revealed that these two populations behaved differently from one another and from previously characterized (early deletional) responses of naive CD4(+) T cells to PIT. Most notably, allergen-reactive CD62L(lo) Th2 cells were long-lived within the lung after PIT, before allergen challenge, in contrast to CD62L(hi) Th2 cells. Despite this, PIT was most potent against CD62L(lo) Th2 cells in protecting from AAI, impairing their ability to produce Th2 cytokines, whereas this capacity was heightened in PIT-treated CD62L(hi) Th2 cells. We conclude that Th2 cells do not undergo an early deletional form of tolerance after PIT. Moreover, memory Th2 subsets respond differently to PIT. These findings have implications for the clinical translation of PIT in different allergic scenarios.
Project description:Allergic asthma is a chronic inflammatory remitting-relapsing disease affecting the airways. Long-lived allergen-specific memory CD4<sup>+</sup> T helper 2 (Th2) cells in mice persist in lungs for more than 2 years after the induction of experimental allergic asthma (EAA). To further understand lung Th2 memory cells, we tracked CD4<sup>+</sup> T cells in spleen and lungs from healthy mice, through the initiation of acute EAA, recovery (remission), and allergen-induced disease relapse. We identified a lung CD3<sup>+</sup>CD4<sup>+</sup> cell subset that expresses CD44<sup>hi</sup>CD62L<sup>-</sup>CD69<sup>+</sup>ST2<sup>+</sup>, produces Th2 cytokines, and mediates allergen-induced disease relapse despite treatment with FTY720 and anti-CD4 antibody. These cells reside in the lung tissue for the lifetime of mice (>665 days) and represent long-lived pathogenic Th2 tissue resident memory cells (T<sub>RMs</sub>) that maintain "allergic memory" in lung. We speculate that these data implicate that human Th2-T<sub>RMs</sub> sentinels in lungs of patients are poised to rapidly respond to inhaled allergen and induce asthma attacks and that therapeutic approaches targeting these cells may provide relief to patients with allergic asthma.
Project description:Chronic helminth infection with Schistosoma (S.) mansoni protects against allergic airway inflammation (AAI) in mice and is associated with reduced Th2 responses to inhaled allergens in humans, despite the presence of schistosome-specific Th2 immunity. Schistosome eggs strongly induce type 2 immunity and allow to study the dynamics of Th2 versus regulatory responses in the absence of worms. Treatment with isolated S. mansoni eggs by i.p. injection prior to induction of AAI to ovalbumin (OVA)/alum led to significantly reduced AAI as assessed by less BAL and lung eosinophilia, less cellular influx into lung tissue, less OVA-specific Th2 cytokines in lungs and lung-draining mediastinal lymph nodes and less circulating allergen-specific IgG1 and IgE antibodies. While OVA-specific Th2 responses were inhibited, treatment induced a strong systemic Th2 response to the eggs. The protective effect of S. mansoni eggs was unaltered in ?MT mice lacking mature (B2) B cells and unaffected by Treg cell depletion using anti-CD25 blocking antibodies during egg treatment and allergic sensitization. Notably, prophylactic egg treatment resulted in a reduced influx of pro-inflammatory, monocyte-derived dendritic cells into lung tissue of allergic mice following challenge. Altogether, S. mansoni eggs can protect against the development of AAI, despite strong egg-specific Th2 responses.
Project description:There is emerging evidence that stem cells can rejuvenate damaged cells by mitochondrial transfer. Earlier studies show that epithelial mitochondrial dysfunction is critical in asthma pathogenesis. Here we show for the first time that Miro1, a mitochondrial Rho-GTPase, regulates intercellular mitochondrial movement from mesenchymal stem cells (MSC) to epithelial cells (EC). We demonstrate that overexpression of Miro1 in MSC (MSCmiro(Hi)) leads to enhanced mitochondrial transfer and rescue of epithelial injury, while Miro1 knockdown (MSCmiro(Lo)) leads to loss of efficacy. Treatment with MSCmiro(Hi) was associated with greater therapeutic efficacy, when compared to control MSC, in mouse models of rotenone (Rot) induced airway injury and allergic airway inflammation (AAI). Notably, airway hyperresponsiveness and remodeling were reversed by MSCmiro(Hi) in three separate allergen-induced asthma models. In a human in vitro system, MSCmiro(Hi) reversed mitochondrial dysfunction in bronchial epithelial cells treated with pro-inflammatory supernatant of IL-13-induced macrophages. Anti-inflammatory MSC products like NO, TGF-?, IL-10 and PGE2, were unchanged by Miro1 overexpression, excluding non-specific paracrine effects. In summary, Miro1 overexpression leads to increased stem cell repair.
Project description:IL-2 plays a critical role in the induction and maintenance of FoxP3-expressing regulatory T cells (FoxP3(+) Tregs). Reduced expression of IL-2 is linked to T-cell-mediated autoimmune diseases such as type 1 diabetes (T1D), in which an imbalance between FoxP3(+) Tregs and pathogenic T effectors exists. We investigated the contribution of IL-2 to dysregulation of FoxP3(+) Tregs by comparing wildtype NOD mice with animals congenic for a C57BL/6-derived disease-resistant Il2 allele and in which T-cell secretion of IL-2 is increased (NOD.B6Idd3). Although NOD mice exhibited a progressive decline in the frequency of CD62L(hi) FoxP3(+) Tregs due to an increase in CD62L(lo) FoxP3(+) Tregs, CD62L(hi) FoxP3(+) Tregs were maintained in the pancreatic lymph nodes and islets of NOD.B6Idd3 mice. Notably, the frequency of proliferating CD62L(hi) FoxP3(+) Tregs was elevated in the islets of NOD.B6Idd3 versus NOD mice. Increasing levels of IL-2 in vivo also resulted in larger numbers of CD62L(hi) FoxP3(+) Tregs in NOD mice. These results demonstrate that IL-2 influences the suppressor activity of the FoxP3(+) Tregs pool by regulating the balance between CD62L(lo) and CD62L(hi) FoxP3(+) Tregs. In NOD mice, reduced IL-2 expression leads to an increase in nonsuppressive CD62L(lo) FoxP3(+) Tregs, which in turn correlates with a pool of CD62L(hi) FoxP3(+) Tregs with limited proliferation.
Project description:Compelling evidences point out a crucial role for extracellular nucleotides such as adenosine triphosphate (ATP) during inflammatory conditions. Once released into the extracellular space, ATP modulates migration, maturation and function of various inflammatory cells via activating of purinergic receptors of the P2Y- and P2X- family. P2RX4 is an ATP-guided ion channel expressed on structural cells such as alveolar epithelial and smooth muscle cells as well as inflammatory cells including macrophages, dendritic cells (DCs) and T cells. P2RX4 has been shown to interact with P2RX7 and promote NLRP3 inflammasome activation. Although P2RX7 has already been implicated in allergic asthma, the role of P2RX4 in airway inflammation has not been elucidated yet. Therefore, we used a selective pharmacological antagonist and genetic ablation to investigate the role of P2RX4 in an ovalbumin (OVA) driven model of allergen-induced airway inflammation (AAI). Both, P2RX4 antagonist 5-BDBD treatment and P2rx4 deficiency resulted in an alleviated broncho alveolar lavage fluid eosinophilia, peribronchial inflammation, Th2 cytokine production and bronchial hyperresponsiveness. Furthermore, P2rx4-deficient bone marrow derived DCs (BMDCs) showed a reduced IL-1ß production in response to ATP accompanied by a decreased P2rx7 expression and attenuated Th2 priming capacity compared to wild type (WT) BMDCs in vitro. Moreover, mice adoptively transferred with P2rx4-deficient BMDCs exhibit a diminished AAI in vivo. In conclusion our data suggests that P2RX4-signaling contributes to AAI pathogenesis by regulating DC mediated Th2 cell priming via modulating IL-1ß secretion and selective P2RX4-antagonists might be a new therapeutic option for allergic asthma.
Project description:Extracellular Adenosine-5'-Triphosphate (ATP) is known to accumulate in the lung, following allergen challenge, and contributes via activation of purinergic receptors on dendritic cells (DC), to the development of allergic airway inflammation (AAI). Extracellular ATP levels in the airways are normally tightly regulated by CD39. This ectonucleotidase is highly expressed by DC purified from skin (Langerhans cells) and bone marrow, and has been shown to modulate DC adaptive/haptenic immune responses. In this study, we have evaluated the impact of Cd39 deletion and associated perturbation of purinergic signaling in AAI.Standard ovalbumin (OVA)-alum and house dust mite (HDM) bone marrow-derived DC (BMDC)-dependent models of AAI were used to study effects of Cd39. Migration assays, time lapse microscopy, and T-cell priming assays were further used to determine functional relevance of Cd39 expression on BMDC in the setting of immune and Th2-mediated responses in these models.Cd39(-/-) mice exhibited marked increases in BALF ATP levels but paradoxically exhibited limited AAI in both OVA-alum and HDM models. These pathophysiological abnormalities were associated with decreased myeloid DC activation and chemotaxis toward ATP, and were linked to purinergic receptor desensitization responses. Further, Cd39(-/-) DCs exhibited limited capacity to both prime Th2 responses and form stable immune synaptic interactions with OVA-transgenic naïve T cells.Cd39-deficient DCs exhibit limited capacity to induce Th2 immunity in a DC-driven model of AAI in vivo. Our data demonstrate a role of CD39 and perturbed purinergic signaling in models of AAI.
Project description:Most memory phenotype (MP) CD44(hi) CD8(+) cells are resting interleukin (IL)-15-dependent cells characterized by high expression of the IL-2/IL-15 receptor beta (CD122). However, some MP CD8(+) cells have a CD122(lo) phenotype and are IL-15 independent. Here, evidence is presented that the CD122(lo) subset of MP CD8(+) cells is controlled largely by major histocompatibility complex (MHC) class I molecules. Many of these cells display surface markers typical of recently activated T cells (CD62L(lo), CD69(hi), CD43(hi), and CD127(lo)) and show a high rate of background proliferation. Cells with this phenotype are highly enriched in common gamma chain-deficient mice and absent from MHC-I(-/-) mice. Unlike CD122(hi) CD8(+) cells, CD122(lo) MP CD8(+) cells survive poorly after transfer to MHC-I(-/-) hosts and cease to proliferate. Although distinctly different from typical antigen-specific memory cells, CD122(lo) MP CD8(+) cells closely resemble the antigen-dependent memory CD8(+) cells found in chronic viral infections.
Project description:How follicular helper T cells (T(FH) cells) differentiate to regulate B cell immunity is critical for effective protein vaccination. Here we define three transcription factor T-bet-expressing antigen-specific effector helper T cell subsets with distinguishable function, migratory properties and developmental programming in vivo. Expression of the transcriptional repressor Blimp-1 distinguished T zone 'lymphoid' effector helper T cells (CD62L(hi)CCR7(hi)) from CXCR5(lo) 'emigrant' effector helper T cells and CXCR5(hi) 'resident' T(FH) cells expressing the transcriptional repressor Bcl-6 (CD62L(lo)CCR7(lo)). We then show by adoptive transfer and intact polyclonal responses that helper T cells with the highest specific binding of peptide-major histocompatibility complex class II and the most restricted T cell antigen receptor junctional diversity 'preferentially' developed into the antigen-specific effector T(FH) compartment. Our studies demonstrate a central function for differences in the binding strength of the T cell antigen receptor in the antigen-specific mechanisms that 'program' specialized effector T(FH) function in vivo.
Project description:The rapid recall of influenza virus-specific CD8(+) T cell effector function is protective, although our understanding of T cell memory remains incomplete. Recent debate has focused particularly on the CD62L lymph node homing receptor. The present analysis shows that although functional memory can be established from both CD62L(hi) and CD62L(lo) CD8(+) T cell subsets soon after initial encounter between naïve precursors and antigen, the optimal precursors are CD8(+)CD44(hi)CD25(lo) immune lymphocytes isolated from draining lymph nodes on day 3.5 after influenza virus infection. Analysis of primed T cells at different times after challenge indicates that the capacity to transfer memory is diminished at the peak of the primary cytotoxic T lymphocyte response, challenging speculations that the transition to memory first requires full differentiation to effector status. It seems that location rather than CD62Lhi/lo phenotype may be the more profitable focus for further dissection of the early establishment of T cell memory.
Project description:Naïve CD4+ T cells were isolated from spleen of AND TcR transgenic/green fluorescence protein (GFP) transgenic mice (Kaye et al., Nature 1989;341:746, Wright et al, Blood 2001;97:2278) that recognize a peptide of pigeon cytochrome C in the context of I-Ek and express CD44lo, CD62Lhi, CD45RBhi, and CD25-. After 4 days in vitro stimulation with antigen presenting cells (APC) under either Th1 or Th2 condition, naïve cells become Th1 or Th2 effector cells expressing CD44hi, CD62L lo, CD45RBhi, and CD25+. Additional 3 days culture in the absence of APC, those effector cells become rested expressing a phenotype similar to memory cells (CD44 hi, CD62L lo, CD45RB lo and CD25-). These rested effector cells were adaptively transferred into thymectomized, lethally irradiated, and T cell depleted bone marrow reconstituted mice and memory cells were isolated after 4-12 weeks by flow sort. Generation and purification of Th1 and Th2 effector and memory CD4+ T cells of 42 samples.