Adherence of adoptively transferred alloreactive Th1 cells in lung: partial dependence on LFA-1 and ICAM-1

Noninvasive Immuno-PET Imaging of CD8+ T Cell Behavior in Influenza A Virus-Infected Mice

Immuno-positron emission tomography (immuno-PET) is a noninvasive imaging method that enables tracking of immune cells in living animals. We used a nanobody that recognizes mouse CD8α and labeled it with ⁸⁹Zr to image mouse CD8⁺ T cells in the course of an infection with influenza A virus (IAV). The CD8⁺ signal showed a strong increase in the mediastinal lymph node (MLN) and thymus as early as 4 days post-infection (dpi), and as early as 6 dpi in the lungs. Over the course of the infection, CD8⁺ T cells were at first distributed diffusely throughout the lungs and then accumulated more selectively in specific regions of the lungs. These distributions correlated with morbidity as mice reached the peak of weight loss over this interval. CD8⁺ T cells obtained from control or IAV-infected mice showed a difference in their distribution and migration when comparing their fate upon labeling ex vivo with ⁸⁹Zr-labeled anti-CD8α nanobody and transfer into infected versus control animals. CD8⁺ T cells from infected mice, upon transfer, appear to be trained to persist in the lungs, even of uninfected mice. Immuno-PET imaging thus allows noninvasive, dynamic monitoring of the immune response to infectious agents in living animals.

Enhanced CD103 Expression and Reduced Frequencies of Virus-Specific CD8+ T Cells Among Airway Lymphocytes After Influenza Vaccination of Mice Deficient in Vitamins A + D

Previous research has evaluated antibody responses toward an influenza virus vaccine in the context of deficiencies for vitamins A and D (VAD+VDD). Results showed that antibodies and antibody-forming cells in the respiratory tract were reduced in VAD+VDD mice. However, effectors were recovered when oral supplements of vitamins A + D were delivered at the time of vaccination. Here we address the question of how vaccine-induced CD8+ T cell responses are affected by deficiencies for vitamins A + D. VAD+VDD and control mice were vaccinated with an intranasal, cold-adapted influenza virus A/Puerto Rico/8/34 vaccine, with or without oral supplements of vitamins A + D. Results showed that the percentages of vaccine-induced CD8+ T cell and total CD4+ T cell responses were low among lymphocytes in the airways of VAD+VDD animals compared to controls. The CD103 membrane marker, a protein that binds e-cadherin (expressed on respiratory tract epithelial cells), was unusually high on virus-specific T cells in VAD+VDD mice compared to controls. Interestingly, when T cells specific for the PA224-233/Db epitope were compared with T cells specific for the NP366-374/Db epitope, the former population was more strongly positive for CD103. Preliminary experiments revealed normal or above-normal percentages for vaccine-induced T cells in airways when VAD+VDD animals were supplemented with vitamins A + D at the time of vaccination and on days 3 and 7 after vaccination. Our results suggest that close attention should be paid to levels of vitamins A and D among vaccine recipients in the clinical arena, as low vitamin levels may render individuals poorly responsive to vaccines.

Adoptive Transfer of Engineered Rhesus Simian Immunodeficiency Virus-Specific CD8+ T Cells Reduces the Number of Transmitted/Founder Viruses Established in Rhesus Macaques

AIDS virus infections are rarely controlled by cell-mediated immunity, in part due to viral immune evasion and immunodeficiency resulting from CD4+ T-cell infection. One likely aspect of this failure is that antiviral cellular immune responses are either absent or present at low levels during the initial establishment of infection. To test whether an extensive, timely, and effective response could reduce the establishment of infection from a high-dose inoculum, we adoptively transferred large numbers of T cells that were molecularly engineered with anti-simian immunodeficiency virus (anti-SIV) activity into rhesus macaques 3 days following an intrarectal SIV inoculation. To measure in vivo antiviral activity, we assessed the number of viruses transmitted using SIVmac239X, a molecularly tagged viral stock containing 10 genotypic variants, at a dose calculated to transmit 12 founder viruses. Single-genome sequencing of plasma virus revealed that the two animals receiving T cells expressing SIV-specific T-cell receptors (TCRs) had significantly fewer viral genotypes than the two control animals receiving non-SIV-specific T cells (means of 4.0 versus 7.5 transmitted viral genotypes; P = 0.044). Accounting for the likelihood of transmission of multiple viruses of a particular genotype, the calculated means of the total number of founder viruses transmitted were 4.5 and 14.5 in the experimental and control groups, respectively (P = 0.021). Thus, a large antiviral T-cell response timed with virus exposure can limit viral transmission. The presence of strong, preexisting T-cell responses, including those induced by vaccines, might help prevent the establishment of infection at the lower-exposure doses in humans that typically transmit only a single virus.

IMPORTANCE

The establishment of AIDS virus infection in an individual is essentially a race between the spreading virus and host immune defenses. Cell-mediated immune responses induced by infection or vaccination are important contributors in limiting viral replication. However, in human immunodeficiency virus (HIV)/SIV infection, the virus usually wins the race, irreversibly crippling the immune system before an effective cellular immune response is developed and active. We found that providing an accelerated response by adoptively transferring large numbers of antiviral T cells shortly after a high-dose mucosal inoculation, while not preventing infection altogether, limited the number of individual viruses transmitted. Thus, the presence of strong, preexisting T-cell responses, including those induced by vaccines, might prevent infection in humans, where the virus exposure is considerably lower.

Distribution of adoptively transferred porcine T-lymphoblasts tracked by (18)F-2-fluoro-2-deoxy-D-glucose and position emission tomography

INTRODUCTION

Autologous or allogeneic transfer of tumor-infiltrating T-lymphocytes is a promising treatment for metastatic cancers, but a major concern is the difficulty in evaluating cell trafficking and distribution in adoptive cell therapy. This study presents a method of tracking transfusion of T-lymphoblasts in a porcine model by (18)F-2-fluoro-2-deoxy-d-glucose ([(18)F]FDG) and positron emission tomography.

METHODS

T-lymphoblasts were labeled with the positron-emitting tracer [(18)F]FDG through incubation. The T-lymphoblasts were administered into the bloodstream, and the distribution was followed by positron emission tomography for 120 min. The cells were administered either intravenously into the internal jugular vein (n=5) or intraarterially into the ascending aorta (n=1). Two of the pigs given intravenous administration were pretreated with low-molecular-weight dextran sulphate.

RESULTS

The cellular kinetics and distribution were readily quantifiable for up to 120 min. High (78.6% of the administered cells) heterogeneous pulmonary uptake was found after completed intravenous transfusion. The pulmonary uptake was decreased either by preincubating and coadministrating the T-lymphoblasts with low-molecular-weight dextran sulphate or by administrating them intraarterially.

CONCLUSIONS

The present work shows the feasibility of quantitatively monitoring and evaluating cell trafficking and distribution following administration of [(18)F]FDG-labeled T-lymphoblasts. The protocol can potentially be transferred to the clinical setting with few modifications.

The differential role of L-selectin and ICAM-1 in Th1-type and Th2-type contact hypersensitivity

Sensitization and challenge using DNFB induce contact hypersensitivity (CHS) with predominant type 1 helper (Th1) cell infiltration, whereas those using FITC generate CHS with Th2 cell infiltration. CHS results from inflammatory cell infiltration, a process that is highly regulated by the expression of multiple adhesion molecules. We attempted to determine the role of L-selectin and ICAM-1 in Th1- and Th2-type CHS induced by DNFB or FITC in mice lacking either L-selectin, ICAM-1, or both. Th1-type CHS induced by DNFB was inhibited by L-selectin and/or ICAM-1 deficiency, which was associated with reduced IFN-gamma expression. Similarly, Th2-type CHS induced by FITC was inhibited by L-selectin deficiency. However, Th2-type CHS was increased by ICAM-1 deficiency and accompanied by increased Th2 cytokine expression. Infiltration of in vitro-generated Th1 cells into the FITC-challenged skin decreased in ICAM-1-deficient mice, whereas in vitro-generated Th2 cell infiltration increased, suggesting that ICAM-1 mediates Th1 cell migration and that in the absence of ICAM-1, Th1 cell recruitment decreased, whereas relative Th2 cell migration increased. These results suggest that ICAM-1 mediates Th1 cell recruitment irrespective of DNFB or FITC and that L-selectin recruits Th1 cells in Th1-type CHS, whereas it recruits Th2 cells in Th2-type CHS.

Trafficking, persistence, and activation state of adoptively transferred allogeneic and autologous Simian Immunodeficiency Virus-specific CD8(+) T cell clones during acute and chronic infection of rhesus macaques

Despite multiple lines of evidence suggesting their involvement, the precise role of CD8(+) T cells in controlling HIV replication remains unclear. To determine whether CD8(+) T cells can limit retroviral replication in the absence of other immune responses, we transferred 1-13 x 10(9) allogeneic in vitro expanded SIV-specific CD8(+) T cell clones matched for the relevant restricting MHC-I allele into rhesus macaques near the time of i.v. SIV challenge. Additionally, in vitro expanded autologous SIV-specific CD8(+) T cell clones were infused 4-9 mo postinfection. Infused cells did not appreciably impact acute or chronic viral replication. The partially MHC-matched allogeneic cells were not detected in the blood or most tissues after 3 d but persisted longer in the lungs as assessed by bronchoalveolar lavage (BAL). Autologous cells transferred i.v. or i.p. were found in BAL and blood samples for up to 8 wk postinfusion. Interestingly, despite having a nominally activated phenotype (CD69(+)HLA-DR(+)), many of these cells persisted in the BAL without dividing. This suggests that expression of such markers by T cells at mucosal sites may not reflect recent activation, but may instead identify stable resident memory T cells. The lack of impact following transfer of such a large number of functional Ag-specific CD8(+) T cells on SIV replication may reflect the magnitude of the immune response required to contain the virus.

CXCR3 ligands contribute to Th1-induced inflammation but not to homing of Th1 cells into the lung

Th1 cells are implicated in numerous pulmonary inflammatory disorders, and adoptive transfer of alloreactive Th1 cells mediates lung injury and inflammation in mice. In response to Th1-mediated immune injury, CXCR3 ligands IP10 and MIG are markedly induced. Because Th1 cells express high levels of CXCR3, their recruitment and activity may be influenced by CXCR3 ligands. To examine the role of CXCR3 ligands, the authors inhibited CXCR3-ligand interaction by 2 approaches: (1) antibody ablation of CXCR3 ligands IP10 (CXCL10/interferon-gamma -inducible 10-kDa protein) and MIG (CXCL9/monokine-induced by interferon-gamma), and (2) use of cxcr3(-/-) mice. Antibody neutralization of IP10 and MIG reduced Th1-cell mediated lung inflammation but did not alter Th1-cell influx in the lung. In contrast, a lack of CXCR3 on host cells had no effect on Th1 cells influx or acute inflammation. In vitro, ablation of endogenous IP10 and MIG inhibited antigen-mediated Th1-cell proliferation. These results suggest that the influx of alloreactive Th1 cells into the lung does not require CXCR3 ligands, but that these chemokines do affect Th1-cell proliferation and activity within the affected tissue. Other CXCR3(+) leukocytes do not contribute to acute alloimmune injury.

T‐cell memory and recall responses to respiratory virus infections

The respiratory tract is characterized by its large surface area and the close association of an extensive vasculature with the external environment. As such, the respiratory tract is a major portal of entry for many pathogens. The immune system is able to effectively control most pulmonary pathogens and establish immunological memory that is capable of mediating an accelerated and enhanced recall response to secondary pathogen challenge. A key component of the recall response in the lung involves the rapid response of antigen-specific memory CD8+ T cells. Recent studies have shown that memory CD8+ T cells are extremely heterogeneous in terms of phenotype, function, anatomical distribution, and longevity. However, we have little understanding of how the different subsets of memory cells actually contribute to the recall response, especially with respect to peripheral or mucosal sites, such as the lung. Since immunological memory is the cornerstone of vaccination, it is essential that we understand how different memory CD8+ T-cell subsets are initially generated, maintained over time, and contribute to recall responses. This review focuses on memory T cells that mediate recall responses to influenza and parainfluenza virus infections in the lung.

T cell memory in the lung airways

The respiratory tract poses a substantial challenge to the immune system due to its large surface area, an extensive vasculature that is in very close proximity to the external environment, and repeated exposure to potentially pathogenic organisms in the air. Yet many lung pathogens are controlled by appropriate immune responses. The underlying mechanisms of the adaptive cellular immune response in protecting the respiratory tract are poorly understood. Recently, it has emerged that memory CD4(+) and CD8(+) T cells are present in the lung airways, and evidence is mounting that these cells play a key role in pulmonary immunity to pathogen challenge by immediately engaging the pathogen at the site of infection when pathogen loads are low. For example, in the case of respiratory virus infections, there is evidence that both CD4(+) and CD8(+) memory cells in the lung airways mediate substantial control of a secondary respiratory virus infection in the lungs. Here we address recent developments in our understanding of lung airway memory T cells and their role in infectious disease.

Preferential migration of effector CD8+ T cells into the interstitium of the normal lung

The respiratory tract is a primary site of infection and exposure to environmental antigens and an important site of memory T cell localization. We analyzed the migration and retention of naive and activated CD8+ T cells within the noninflamed lungs and quantitated the partitioning of adoptively transferred T cells between the pulmonary vascular and interstitial compartments. Activated but not naive T cells were retained within the lungs for a prolonged period. Effector CD8+ T cells preferentially egressed from the pulmonary vascular compartment into the noninflamed pulmonary interstitium. T cell retention within the lung vasculature was leukocyte function antigen-1 dependent, while the egress of effector T cells from the vascular to the interstitium functions through a pertussis toxin-sensitive (PTX-sensitive) mechanism driven in part by constitutive CC chemokine ligand 5 expression in the lungs. These results document a novel mechanism of adhesion receptor- and pulmonary chemokine-dependent regulation of the migration of activated CD8+ T cells into an important nonlymphoid peripheral site (i.e., the normal/noninflamed lung).

A role for CD54 (intercellular adhesion molecule-1) in leukocyte recruitment to the lung during the development of experimental idiopathic pneumonia syndrome

BACKGROUND

Idiopathic pneumonia syndrome (IPS) is a frequently fatal complication of allogeneic bone marrow transplantation (BMT). IPS is associated with elevated bronchoalveolar lavage (BAL) fluid levels of tumor necrosis factor-alpha and lipopolysaccharide, both of which are potent activators of endothelial cells (ECs). EC expression of the adhesion molecule CD54 (intercellular adhesion molecule [ICAM]-1) has been shown to be a major regulator of pulmonary inflammation in various experimental models.

METHODS

Using a well-established murine BMT system in which lung injury and graft-versus-host disease (GvHD) are induced by minor histocompatibility antigenic differences between donor and host, the RNase Protection Assay, mice deficient in ICAM-1 expression, and a monoclonal blocking antibody to ICAM, we evaluated the role of the pulmonary vascular expression of CD54 in the development of IPS.

RESULTS

Enhanced pulmonary vascular expression of ICAM-1 coincided with the development of IPS. When ICAM-1 -/- mice were used as allogeneic BMT recipients, IPS severity (measured by lung histopathology, BAL cellularity, and cytokine expression) was significantly reduced compared with wild-type controls. Similar results were also observed when wild-type recipients were treated with a monoclonal blocking antibody to ICAM-1. Surprisingly, ICAM-1 had differential effects on leukocyte infiltration into GvHD target organs; ICAM-1 deficiency had no impact on intestinal histopathology, whereas ICAM-1-/- BMT recipients had significantly enhanced hepatic injury.

CONCLUSIONS

These data demonstrate that although the expression of ICAM-1 is critical for the development of IPS, different mechanisms of leukocyte recruitment are operative in other GvHD target organs.

Populations of human T lymphocytes that traverse the vascular endothelium stimulated by Borrelia burgdorferi are enriched with cells that secrete gamma interferon

Some diseases are characterized by prevalence in the affected tissues of type 1 T lymphocytes, which secrete gamma interferon (IFN-gamma) and other proinflammatory cytokines. For example, type 1 T cells predominate in the lesions of patients with Lyme disease, which is caused by the bacterium Borrelia burgdorferi. We used an in vitro model of the blood vessel wall to test the premise that the vascular endothelium actively recruits circulating type 1 T cells to such lesions. When T lymphocytes isolated from human peripheral blood were examined, the populations that traversed monolayers of resting human umbilical vein endothelial cells (HUVEC) or HUVEC stimulated by interleukin-1beta or B. burgdorferi were markedly enriched for T cells that produced IFN-gamma compared to the initially added population of T cells. No enrichment was seen for cells that produced interleukin-4, a marker for type 2 T lymphocytes. Very late antigen-4 and CD11/CD18 integrins mediated passage of the T cells across both resting and stimulated HUVEC, and the endothelium-derived chemokine CCL2 (monocyte chemoattractant protein 1) was responsible for the enhanced migration of T cells across stimulated HUVEC. These results suggest that the vascular endothelium may contribute to the selective accumulation of type 1 T cells in certain pathological lesions, including those of Lyme disease.

Trafficking of Th1 cells to lung: a role for selectins and a P-selectin glycoprotein-1-independent ligand

Trafficking of lymphocytes to lung is a critical component of pulmonary immune defense and surveillance. Selectins, expressed on vascular endothelium, regulate T lymphocyte emigration into tissues, such as skin, but the role of the selectins in trafficking of T cells to lung has not been well characterized. Here, we used a model of lung inflammation induced by adoptive transfer of alloreactive Th1 cells to analyze the role of P- and E-selectin in Th1 cell trafficking to lung in vivo. We found that both P- and E-selectin play an important role in Th1 lymphocyte migration to lung. We confirmed that the Th1 cells express P-selectin glycoprotein ligand-1, which was functional in binding to P- and E-selectin in vitro. However, our studies reveal that a ligand distinct from P-selectin glycoprotein-1 also binds these selectins in vitro and appears to play a physiologic role in in vivo emigration of Th1 lymphocytes into the lung.

Overlapping and selective roles of endothelial intercellular adhesion molecule-1 (ICAM-1) and ICAM-2 in lymphocyte trafficking

The integrin LFA-1 interacts with a variety of ligands termed ICAMs. ICAM-1 and ICAM-2 are both expressed on endothelium and serve as counterreceptors during lymphocyte trafficking. In this study, we analyzed their relative contribution to lymphocyte recirculation through lymph nodes and to recruitment into lung and inflamed skin by blocking mAbs against ICAM-1 and ICAM-2 and mice deficient for ICAM-1. The entry of lymphocytes into peripheral and mesenteric lymph nodes was found to be unaffected by the functional deletion of either ICAM-1 or ICAM-2. However, when both pathways were blocked, recirculation through lymph nodes was strongly reduced. Trapping of lymphocytes in the lung after i.v. injection is partly mediated by LFA-1/ICAM interactions; the data presented in this study show an exclusive role of ICAM-1 in LFA-1-dependent lung trapping. Similarly, ICAM-1, but not ICAM-2, was required for the migration of T effector cells into the inflamed skin. These results indicate that ICAM-1 and ICAM-2 have redundant functions in lymphocyte recirculation through lymph nodes, but ICAM-1 is unique in supporting migration into inflamed sites and trapping within the lung.

LFA-1 is required for retention of effector CD8 T cells in mouse lungs

The adhesion molecules involved in the migration and retention of activated effector CD8 T cells in the lung microcirculation and their recruitment into lung tissue are largely unknown. Here, we have analyzed the role of lymphocyte function-associated antigen-1 (LFA-1) and very late antigen-4 (VLA-4) on adhesion of influenza hemagglutinin (HA)-specific CD8 T-cell clone D4 under shear conditions in an in vitro binding assay and in an in vivo homing assay to the lungs of naive or transgenic Balb/c mice expressing HA (HA-Tg) by a lung-specific promoter. Blocking LFA-1 or intercellular adhesion molecule 1 (ICAM-1) significantly inhibited adhesion of D4 cells to lung vascular endothelium and parenchyma of lung sections. However, blocking VLA-4 or vascular cell adhesion molecule 1 (VCAM-1) had no effect on cell adhesion. Blocking LFA-1 in vivo significantly delayed lethal injury following adoptive transfer of D4 cells into HA-Tg mice as assessed by weight loss and histology. Residence time of adoptively transferred Indium 111 (111In)-labeled D4 cells in lungs of normal and HA-Tg mice as analyzed by dual modality imaging revealed a significantly shorter transit time of 4 hours for the D4 cells upon in vivo blockade of LFA-1. These results demonstrate a crucial role for LFA-1 in retention of activated CD8 T cells in normal mouse lungs and in the progression of lethal injury in HA-Tg mice.

Perivascular capillaries in the lung: an important but neglected vascular bed in immune reactions?

In allergic and inflammatory immune reactions of the respiratory tract, leukocytes migrate into the different compartments of the lung. The air space can easily be sampled by means of bronchoalveolar lavage. However, the subset composition in the bronchial wall or the lung interstitium often differs considerably from that of the bronchoalveolar lavage fluid. A further compartment involved in very heterogeneous immune reactions in the lung has thus far not been mentioned: the periarterial space. In numerous experiments in different species with virus, bacteria, fungi, or allergens, there was not only a leukocyte infiltration of the bronchial lamina propria but also infiltration around branches of the pulmonary artery. This thus far neglected compartment consists of a different type of capillary. Thus it is important not to overlook this area in studies on allergic or inflammatory immune reactions of the lung.

Is IL12 necessary in experimental hypersensitivity pneumonitis?

Inhalation of Saccharopolyspora rectivirgula (SR) can cause the disease Farmer's Lung, a classic example of hypersensitivity pneumonitis. Th1, but not Th2, cell lines can adoptively transfer experimental hypersensitivity pneumonitis (EHP). Substantial amounts of IL12 appear in bronchoalveolar lavage fluid (BALF) after a single intratracheal (IT) injection of SR, and SR-induced IL12 secretion by both a macrophage cell line and alveolar macrophages. We tested the hypothesis that IL12 is essential for the development of EHP by addition of anti-IL12 to cultured cells, and adoptive transfer of EHP in IL12p40-/- animals. We transferred SR cultured spleen and lung associated lymph node cells from SR sensitized mice (both IL12p40-/- and wild type), to naïve recipients (both wild type and IL12p40-/-). The addition of anti-IL12 to cultures of sensitized cells could not ablate the ability of these cells to transfer EHP. Cultured cells from IL12p40-/- animals were fully capable of transferring EHP. In contrast, IL12p40-/- recipients of both wild type and IL12p40-/--cultured cells were less able to express EHP (lung histology and BALF characteristics) than wild type mice, and had more eosinophils in both lung tissue and BALF. We conclude that IL12 is not necessary for development of cells able to adoptively transfer EHP, but that it is required for full expression of EHP in recipient animals.