IL-4/IL-4 Ab complex enhances the accumulation of both antigen-specific and bystander CD8 T cells in mouse lungs infected with influenza A virus.

BACKGROUND: Unlike conventional T cells, innate and virtual-memory CD8 T cells in naïve mice acquire their memory phenotypes and functions in the absence of antigenic encounters in a cytokine-dependent manner. The relevant cytokines include interleukin-4 (IL-4), type I interferon, and interleukin-15 (IL-15). Moreover, exogenous IL-4 can also induce de novo generation and/or expansion of the virtual-memory CD8 T cell population. In this study, we investigated whether exogenous IL-4 could enhance the immune response to a viral infection. RESULTS: In vivo administration of IL-4 and an anti-IL-4 antibody complex (IL-4C) increased CXCR3 expression in both memory and naïve phenotype CD8 T cells in the absence of antigenic stimulation, and protected mice from lethal influenza infection. Flow cytometric analysis of lung-infiltrating immune cells on day 5 after virus infection revealed higher numbers of antigen-specific and bystander CD8 T cells in IL-4C-treated mice than in control mice. In particular, the bystander CD8 T cells were a naïve or evident memory phenotypes. Crucially, an anti-CXCR3 blocking antibody abrogated this IL-4C effect, reflecting that the increased accumulation of CD8 T cells in the lungs after IL-4C treatment is dependent on CXCR3. CONCLUSIONS: These data demonstrate that exogenous IL-4C plays a protective role by enhancing CXCR3-dependent migration of CD8 T cells into influenza-infected lungs.

Prevention of severe lung immunopathology associated with influenza infection through adeno-associated virus vector administration.

BACKGROUND: Influenza A viruses (IAVs) have long posed a threat to humans, occasionally causing significant morbidity and mortality. The initial immune response is triggered by infected epithelial cells, alveolar macrophages and dendritic cells. However, an exaggerated innate immune response can result in severe lung injury and even host mortality. One notable pathology observed in hosts succumbing to severe influenza is the excessive influx of neutrophils and monocytes into the lung. In this study, we investigated a strategy for controlling lung immunopathology following severe influenza infection. RESULTS: To evaluate the impact of innate immunity on influenza-associated lung injury, we employed CB17.SCID and NOD.SCID mice. NOD.SCID mice exhibited slower weight loss and longer survival than CB17.SCID mice following influenza infection. Lung inflammation was reduced in NOD.SCID mice compared to CB17.SCID mice. Bulk RNA sequencing analysis of lung tissue showed significant downregulation of 827 genes, and differentially expressed gene analysis indicated that the cytokine-cytokine receptor interaction pathway was predominantly downregulated in NOD.SCID mice. Interestingly, the expression of the Cxcl14 gene was higher in the lungs of influenza-infected NOD.SCID mice than in CB17.SCID mice. Therefore, we induced overexpression of the Cxcl14 gene in the lung using the adeno-associated virus 9 (AAV9)-vector system for target gene delivery. However, when we administered the AAV9 vector carrying the Cxcl14 gene or a control AAV9 vector to BALB/c mice from both groups, the morbidity and mortality rates remained similar. Both groups exhibited lower morbidity and mortality than the naive group that did not receive the AAV9 vector prior to IAV infection, suggesting that the pre-administration of the AAV9 vector conferred protection against lethal influenza infection, irrespective of Cxcl14 overexpression. Furthermore, we found that pre-inoculation of BALB/c mice with AAV9 attenuated the infiltration of trans-macrophages, neutrophils and monocytes in the lungs following IAV infection. Although there was no difference in lung viral titers between the naive group and the AAV9 pre-inoculated group, pre-inoculation with AAV9 conferred lung injury protection against lethal influenza infection in mice. CONCLUSIONS: Our study demonstrated that pre-inoculation with AAV9 prior to IAV infection protected mouse lungs from immunopathology by reducing the recruitment of inflammatory cells.

CD1b glycoprotein, a crucial marker of thymocyte development during T cell maturation in cynomolgus monkeys.

Phenotypic markers that denote different developmental stages of thymocytes are important for understanding T cell development in the thymus. Here, we show that CD1b is a critical discriminator of thymocyte maturation stage in cynomolgus monkeys. CD1b was expressed by immature thymocytes prior to ß-selection, and its expression decreased as cells became fully mature in the thymus. MHC-I expression was lowest at the CD3loCD1b+ immature double-positive (DP) stage, while the ratio of CD1d:MHC-I expression was significantly higher at this stage than at other developmental stages. PLZF was expressed by < 0.2% of thymocytes; most PLZF+ thymocytes were CD3-/loCD1b+ immature DP thymocytes with the potential to produce IL-4. EOMES+ thymocytes, which accounted for > 2% of total thymocytes, were mostly CD3+CD1b- mature thymocytes and predominantly of the CD8 single-positive (SP) lineage. An unconventional CD8+ T cell subset expressing the NKG2AC+CXCR3+ innate-like T cell marker was identified within the EOMES+ CD8 SP lineage; these cells exhibited a memory phenotype. Taken together, these findings show that CD1b is a valuable discriminatory marker of thymocyte development. The data presented herein can be used to characterize the features of PLZF- and EOMES-associated unconventional T cells in the thymus.

Heterogeneity of circulating CD4+CD8+ double-positive T cells characterized by scRNA-seq analysis and trajectory inference.

The frequency of CD4+CD8+ double-positive (DP) T cells is highly associated with a variety of diseases. Recently, we used high-throughput single-cell RNA sequencing to show that circulating DP T cells in cynomolgus monkeys comprise nine heterogeneous populations. To better understand the characteristics of DP T cells, we analyzed 7601 cells from a rhesus monkey and detected 14,459 genes. Rhesus monkey DP T cells comprised heterogeneous populations (naïve, Treg-, Tfh-, CCR9+ Th-, Th17-, Th2-, Eomes+ Tr1-, CTL-, PLZF+ innate- and Eomes+ innate-like cells) with multiple potential functions. We also identified two new subsets using aggregated scRNA-seq datasets from the rhesus and the cynomolgus monkey: CCR9+ Th-like cells expressing ICAM2 and ITGA1, and PLZF+ innate-like cells that display innate-associated gene signatures such as ZBTB16, TYROBP, MAP3K8, and KLRB1. Trajectory inference of cell differentiation status showed that most DP T cells in the rhesus monkey were found in the mid-to-late pseudotime, whereas DP T cells from the cynomolgus monkey were found in early pseudotime. This suggests that DP T cells in rhesus monkeys may exhibit more diverse differentiation states than those in cynomolgus monkeys. Thus, scRNA-seq and trajectory inference identified a more diverse subset of the circulating DP T cells than originally thought.

Cellular heterogeneity of circulating CD4+CD8+ double-positive T cells characterized by single-cell RNA sequencing.

Circulating CD4+CD8+ double-positive (DP) T cells are associated with a variety of disease states. However, unlike conventional T cells, the composition of this population is poorly understood. Here, we used single-cell RNA sequencing (scRNA-seq) to analyze the composition and characteristics of the DP T cell population circulating in the peripheral blood of cynomolgus monkeys. We found that circulating DP T cells not only contain a large number of naïve cells, but also comprise a heterogeneous population (CD4 CTL-, Eomes+ Tr1-, Th2-, Th17-, Tfh-, Treg-, CD8 CTL-, and innate-like cells) with multiple potential functions. Flow cytometry analysis revealed that a substantial number of the naïve DP T cells expressed CD8αß, as well as CD8αα, along with high expression of CD31. Moreover, the CD4hiCD8lo and CD4hiCD8hi populations, which express high levels of the CD4 coreceptor, comprised subsets characterized by helper and regulatory functions, some of which also exhibited cytotoxic functions. By contrast, the CD4loCD8hi population with high CD8 coreceptor expression comprised a subset characterized by CD8 CTL- and innate-like properties. Taken together, the data show that scRNA-seq analysis identified a more diverse subset of the circulating DP cells than is currently known, despite this population being very small.

Attenuation of Experimental Autoimmune Encephalomyelitis in a Common Marmoset Model by Dendritic Cell-Modulating Anti-ICAM-1 Antibody, MD-3.

MD-3 is a novel anti-human ICAM-1 monoclonal antibody that induces T cell tolerance in humanized mice via modulation of dendritic cell differentiation and efficiently suppresses the development of collagen-induced arthritis. This effect has also been observed in xenograft rejection in nonhuman primates, where grafts survived for more than 2.5 years following MD-3 administration. Here, we show that MD-3 can attenuate experimental autoimmune encephalomyelitis (EAE) that was induced in common marmoset monkeys by immunization with human myelin oligodendrocyte glycoproteins. MD-3 administration was initiated 1 week after immunization and efficiently delayed the development of EAE phenotypes, although the disease was not completely prevented. Based on the results of histopathological examination, MD-3 treatment greatly suppressed total inflammation with respect to demyelination, as well as T cell and microglial infiltration in the brain. However, the antibody response against myelin oligodendrocyte glycoprotein was not suppressed with this treatment protocol. These observations suggest that the MD-3 antibody has beneficial effects on the treatment of EAE via the suppression of T cell-mediated cellular responses.

UVB-induced depletion of donor-derived dendritic cells prevents allograft rejection of immune-privileged hair follicles in humanized mice.

Dendritic cells (DCs) are key targets for immunity and tolerance induction; they present donor antigens to recipient T cells by donor- and recipient-derived pathways. Donor-derived DCs, which are critical during the acute posttransplant period, can be depleted in graft tissue by forced migration via ultraviolet B light (UVB) irradiation. Here, we investigated the tolerogenic potential of donor-derived DC depletion through in vivo and ex vivo UVB preirradiation (UV) combined with the injection of anti-CD154 antibody (Ab) into recipients in an MHC-mismatched hair follicle (HF) allograft model in humanized mice. Surprisingly, human HF allografts achieved long-term survival with newly growing pigmented hair shafts in both Ab-treated groups (Ab-only and UV plus Ab) and in the UV-only group, whereas the control mice rejected all HF allografts with no hair regrowth. Perifollicular human CD3+ T cell and MHC class II+ cell infiltration was significantly diminished in the presence of UV and/or Ab treatment. HF allografts in the UV-only group showed stable maintenance of the immune privilege in the HF epithelium without evidence of antigen-specific T cell tolerance, which is likely promoted by normal HFs in vivo. This immunomodulatory strategy targeting the donor tissue exhibited novel biological relevance for clinical allogeneic transplantation without generalized immunosuppression.

CD4hiCD8low Double-Positive T Cells Are Associated with Graft Rejection in a Nonhuman Primate Model of Islet Transplantation.

Peripheral CD4/CD8 double-positive (DP) T cells are associated with autoimmune disorders, cancer, and viral infection. However, the relationship between organ transplantation and DP T cells is unclear. Here, we examined the functional characteristics of peripheral DP T cells and analyzed their significance with respect to islet graft rejection in a nonhuman primate model of islet transplantation. DP T cells were functionally equivalent to conventional CD4 and CD8 T cells in terms of helper and cytotoxic activity, respectively. DP T cells expressed high levels of CXCR5 and PD-1 and secreted IFN-γ, IL-4, and IL-21 in amounts equivalent to those secreted by CD4 or CD8 T cells; also, they produced large amounts of granzyme B and perforin. In addition, under steady-state conditions, DP T cells expressed eomesodermin (Eomes) and promyelocytic leukemia zinc finger (PLZF) proteins, both of which act as transcription factors in innate/memory-like T cells. The number of peripheral DP T cells in the islet transplantation model was high in the group that experienced graft rejection; this was not the case in the long-term survival group. Interestingly, numbers of effector memory T cells (TEM) within the DP T cell population increased significantly during islet graft rejection, as did those of TEM within the cytotoxic CD8 T cells. Furthermore, the most conspicuous of which was the increase of CD4hiCD8low T cell subpopulation at that point. Taken together, the data suggest that peripheral DP T cells showing an innate/memory-like phenotype have both helper and cytotoxic activity in vitro and that they may act as a novel biomarker for graft rejection after islet transplantation.

Epitope-based ligation of ICAM-1: Therapeutic target for protection against the development of rheumatoid arthritis.

Identification of a particular epitope on the domain 2 of human ICAM-1 led us to focus on its role in the treatment of rheumatoid arthritis (RA). Key observations from our previous xenotransplantation research included the generation of tolerogenic DCs, antigen-specific T-cell tolerance, and reduced production of inflammatory cytokines. The critically important point is the fact that it works initially on DC maturation. Ligation of this epitope with a recognizing antibody, MD-3, was also able to create a tolerogenic environment in RA in a manner sililar to that created by xenotransplantation. In this study, we noted that the disease progression, in terms of arthritis score and histopathology of joints, was significantly less severe in the MD-3-treated group than in the vehicle-treated group. Defective production of IL-6 and reduced proliferation of collagen-specific T cells were most remarkable laboratory findings. This type of ligation has a greater advantage over other types of therapeutics, in a sense that simple injection of this antibody inhibits antigen-specific T cell response. Due to the possibility of viral infection in this process, we regularly monitored cytomegalovirus reactivation status without detection of any viral gene replication. We are hoping that remarkable specializations that this interaction has, would be a promising target for therapeutic antibody in RA.

RD-05, a novel anti-CD154 antibody, efficiently inhibits generation of anti-drug antibody without the risk of thrombus formation in non-human primates.

Antibody formation against therapeutic agents, such as tumor necrosis factor inhibitors and Factor VIII, that leads to treatment failure has become a major challenge in the treatment of rheumatoid arthritis and hemophilia. It is well known that anti-CD154 antibodies have the highest potential to inhibit these types of adverse immune responses. Nevertheless, the formation of thromboemboli is the major hurdle in the clinical application of these anti-CD154 blocking antibodies. For this, we attempted to derive an idea as to how this major complication can be eliminated. Consequently, we developed a novel anti-CD154 chimeric antibody, which was made by genetic modification of a portion of human IgG4 Fc. This antibody has an almost comparable antigen binding affinity to a previously developed 5C8 clone and near completely inhibited CD40-CD154 interaction and T cell-dependent B cell activation in vitro. Even under the condition, where we injected immune complexes comprised of RD-05 and CD154 antigen, the formation of thromboembolism was not seen in human FcγRIIA-transgenic mice, whereas the converse was exactly true in the case of 5C8 antibody. Notably, just two injections of RD-05 antibody was sufficient to inhibit the antibody formation against adalimumab during 3-4 months in cynomolgus macaques, in which adalimumab was repeatedly injected for 12 weeks. Based on these findings, we suggest that this RD-05 antibody can be applied to antibody-mediated autoimmune diseases, including systemic lupus erythematosus and immune thrombocytopenic purpura.

The effect of epitope-based ligation of ICAM-1 on survival and retransplantation of pig islets in nonhuman primates.

BACKGROUND: Pig islet xenotransplantation is a promising alternative to allogeneic transplantation. However, the wide immunologic barrier between pigs and primates limits the long-term survival of the graft. MD-3, a novel monoclonal antibody (mAb) that recognizes a particular epitope of human ICAM-1, can render T cells tolerant to a xenograft by arresting dendritic cell maturation. We report the long-term survival of adult wild-type pig islets and successful retransplantation in nonhuman primates using a protocol comprising induction with MD-3 mAb and maintenance with anti-CD154 mAb and sirolimus. METHODS: Eleven rhesus monkeys were assigned to three groups. Group 1 (n = 4) involved treatment with MD-3 induction, short-term (<4 months) administration of anti-CD154 mAb, and maintenance therapy with sirolimus. Group 2 (n = 4) involved treatment with MD-3 induction and long-term maintenance therapy with anti-CD154 mAb and sirolimus. Group 3 (n = 3) involved only maintenance therapy with anti-CD154 mAb and sirolimus. Diabetes was induced in monkeys by streptozotocin, and pig islets (61 000-112 000 IEQ/kg for each transplant; up to 280 000 IEQ/kg per recipient) were infused through the portal vein. The in vivo functional potency of the isolated islets was tested by minimal model transplant in streptozotocin-induced diabetic NOD/SCID mice, and the mean AUC of blood glucose level divided by the number of follow-up days was calculated. RESULTS: The islet grafts survived more than 6 months (between 225 and 727 days) in nine of 12 transplants of MD-3-treated groups 1 and 2, whereas in the absence of MD-3 mAb, survival was <40 days. In three transplants of the MD-3-treated Group 2, functional graft survival was only for 104, 125, and 154 days. In these cases, a retrospective analysis suggested that the relatively short survival duration was associated with the relatively high AUC value in the NOD/SCID bioassay. Notably, when retransplantation was performed in Group 3, blood glucose control was extended up to 956 days, which was supported by MD-3 mAb-based suppression of adaptive immunity. No replication of cytomegalovirus genes was observed. CONCLUSIONS: Long-term survival of pig islet xenografts and successful retransplantation were achieved with MD-3 mAb-based immunosuppression regimen in this pig-to-monkey transplantation model. It should be emphasized that these encouraging results were achieved following the transplantation of islets from pigs that had not been genetically modified. Considering that it is possible to further substantially reduce the destruction of grafted islet using genetically modified pig islet, the islet requirement could be reduced and much longer graft survival can be achieved.

Effect of IL-4 on the Development and Function of Memory-like CD8 T Cells in the Peripheral Lymphoid Tissues.

Unlike conventional T cells, innate CD8 T cells develop a memory-like phenotype in the thymus and immediately respond upon antigen stimulation, similar to memory T cells. The development of innate CD8 T cells in the thymus is known to require IL-4, which upregulates Eomesodermin (Eomes). These features are similar to that of virtual memory CD8 T cells and IL-4-induced memory-like CD8 T cells generated in the peripheral tissues. However, the relationship between these cell types has not been clearly documented. In the present study, IL-4-induced memory-like CD8 T cells generated in the peripheral tissues were compared with innate CD8 T cells in terms of phenotype and function. When an IL-4/anti-IL-4 antibody complex (IL-4C) was injected into C57BL/6 mice daily for 7 days, the Eomes(hi)CXCR3 (+) CD8 T cell population was markedly increased in the peripheral lymphoid organs and blood. These cells were generated from naïve CD8 T cells or accumulated via the expansion of pre-existing CD44(hi)CXCR3 (+) CD8 T cells. Initially, the majority of these CXCR3 (+) CD8 T cells expressed low levels of CD44, which was followed by the conversion to the CD44(hi) phenotype. This conversion was associated with the acquisition of enhanced effector function. After discontinuation of IL-4C treatment, Eomes expression levels gradually decreased in CXCR3 (+) CD8 T cells. Taken together, the results of this study demonstrate that IL-4-induced memory-like CD8 T cells generated in the peripheral lymphoid tissues are phenotypically and functionally similar to the innate CD8 T cells generated in the thymus.

PLZF(+) Innate T Cells Support the TGF-ß-Dependent Generation of Activated/Memory-Like Regulatory T Cells.

PLZF-expressing invariant natural killer T cells and CD4 T cells are unique subsets of innate T cells. Both are selected via thymocyte-thymocyte interaction, and they contribute to the generation of activated/memory-like CD4 and CD8 T cells in the thymus via the production of IL-4. Here, we investigated whether PLZF(+) innate T cells also affect the development and function of Foxp3(+) regulatory CD4 T cells. Flow cytometry analysis of the thymus and spleen from both CIITA transgenic C57BL/6 and wild-type BALB/c mice, which have abundant PLZF(+) CD4 T cells and invariant natural killer T cells, respectively, revealed that Foxp3(+) T cells in these mice exhibited a CD103(+) activated/memory-like phenotype. The frequency of CD103(+) regulatory T cells was considerably decreased in PLZF(+) cell-deficient CIITA(Tg)Plzf(lu/lu) and BALB/c.CD1d(-/-) mice as well as in an IL-4-deficient background, such as in CIITA(Tg)IL-4(-/-) and BALB/c.lL-4(-/-) mice, indicating that the acquisition of an activated/memory-like phenotype was dependent on PLZF(+) innate T cells and IL-4. Using fetal thymic organ culture, we further demonstrated that IL-4 in concert with TGF-ß enhanced the acquisition of the activated/memory-like phenotype of regulatory T cells. In functional aspects, the activated/memory-like phenotype of Treg cells was directly related to their suppressive function; regulatory T cells of CIITA(Tg)PIV(-/-) mice more efficiently suppressed ovalbumin-induced allergic airway inflammation compared with their counterparts from wild-type mice. All of these findings suggest that PLZF(+) innate T cells also augmented the generation of activated/memory-like regulation via IL-4 production.