Rorc restrains the potency of ST2+ regulatory T cells in ameliorating intestinal graft-versus-host disease

Soluble stimulation-2 (ST2) is increased during graft-versus-host disease (GVHD), while Tregs that express ST2 prevent GVHD through unknown mechanisms. Transplantation of Foxp3- T cells and Tregs that were collected and sorted from different Foxp3 reporter mice indicated that in mice that developed GVHD, ST2+ Tregs were thymus derived and predominantly localized to the intestine. ST2-/- Treg transplantation was associated with reduced total intestinal Treg frequency and activation. ST2-/- versus WT intestinal Treg transcriptomes showed decreased Treg functional markers and, reciprocally, increased Rorc expression. Rorc-/- T cells transplantation enhanced the frequency and function of intestinal ST2+ Tregs and reduced GVHD through decreased gut-infiltrating soluble ST2-producing type 1 and increased IL-4/IL-10-producing type 2 T cells. Cotransfer of ST2+ Tregs sorted from Rorc-/- mice with WT CD25-depleted T cells decreased GVHD severity and mortality, increased intestinal ST2+KLRG1+ Tregs, and decreased type 1 T cells after transplantation, indicating an intrinsic mechanism. Ex vivo IL-33-stimulated Tregs (TregIL-33) expressed higher amphiregulin and displayed better immunosuppression, and adoptive transfer prevented GVHD better than control Tregs or TregIL-33 cultured with IL-23/IL-17. Amphiregulin blockade by neutralizing antibody in vivo abolished the protective effect of TregIL-33. Our data show that inverse expression of ST2 and RORγt in intestinal Tregs determines GVHD and that TregIL-33 has potential as a cellular therapy avenue for preventing GVHD.

The vimentin intermediate filament network restrains regulatory T cell suppression of graft-versus-host disease

Regulatory T cells (Tregs) are critical for maintaining immune homeostasis. However, current Treg immunotherapies do not optimally treat inflammatory diseases in patients. Understanding the cellular processes that control Treg function may allow for the augmentation of therapeutic efficacy. In contrast to activated conventional T cells, in which protein kinase C-θ (PKC-θ) localizes to the contact point between T cells and antigen-presenting cells, in human and mouse Tregs, PKC-θ localizes to the opposite end of the cell in the distal pole complex (DPC). Here, using a phosphoproteomic screen, we identified the intermediate filament vimentin as a PKC-θ phospho target and show that vimentin forms a DPC superstructure on which PKC-θ accumulates. Treatment of mouse Tregs with either a clinically relevant PKC-θ inhibitor or vimentin siRNA disrupted vimentin and enhanced Treg metabolic and suppressive activity. Moreover, vimentin-disrupted mouse Tregs were significantly better than controls at suppressing alloreactive T cell priming in graft-versus-host disease (GVHD) and GVHD lethality, using a complete MHC-mismatch mouse model of acute GVHD (C57BL/6 donor into BALB/c host). Interestingly, vimentin disruption augmented the suppressor function of PKC-θ-deficient mouse Tregs. This suggests that enhanced Treg activity after PKC-θ inhibition is secondary to effects on vimentin, not just PKC-θ kinase activity inhibition. Our data demonstrate that vimentin is a key metabolic and functional controller of Treg activity and provide proof of principle that disruption of vimentin is a feasible, translationally relevant method to enhance Treg potency.

A critical role for donor-derived IL-22 in cutaneous chronic GVHD

Graft-versus-host disease (GVHD) is the major cause of nonrelapse morbidity and mortality after allogeneic stem cell transplantation (allo-SCT). Prevention and treatment of GVHD remain inadequate and commonly lead to end-organ dysfunction and opportunistic infection. The role of interleukin (IL)-17 and IL-22 in GVHD remains uncertain, due to an apparent lack of lineage fidelity and variable and contextually determined protective and pathogenic effects. We demonstrate that donor T cell-derived IL-22 significantly exacerbates cutaneous chronic GVHD and that IL-22 is produced by highly inflammatory donor CD4+ T cells posttransplantation. IL-22 and IL-17A derive from both independent and overlapping lineages, defined as T helper (Th)22 and IL-22+ Th17 cells. Donor Th22 and IL-22+ Th17 cells share a similar IL-6-dependent developmental pathway, and while Th22 cells arise independently of the IL-22+ Th17 lineage, IL-17 signaling to donor Th22 directly promotes their development in allo-SCT. Importantly, while both IL-22 and IL-17 mediate skin GVHD, Th17-induced chronic GVHD can be attenuated by IL-22 inhibition in preclinical systems. In the clinic, high levels of both IL-17A and IL-22 expression are present in the skin of patients with GVHD after allo-SCT. Together, these data demonstrate a key role for donor-derived IL-22 in patients with chronic skin GVHD and confirm parallel but symbiotic developmental pathways of Th22 and Th17 differentiation.

T cell progenitor therapy-facilitated thymopoiesis depends upon thymic input and continued thymic microenvironment interaction

Infusion of in vitro-derived T cell progenitor (proT) therapy with hematopoietic stem cell transplant aids the recovery of the thymus damaged by total body irradiation. To understand the interaction between proTs and the thymic microenvironment, WT mice were lethally irradiated and given T cell-deficient (Rag1-/-) marrow with WT in vitro-generated proTs, limiting mature T cell development to infused proTs. ProTs within the host thymus led to a significant increase in thymic epithelial cells (TECs) by day 21 after transplant, increasing actively cycling TECs. Upon thymus egress (day 28), proT TEC effects were lost, suggesting that continued signaling from proTs is required to sustain TEC cycling and cellularity. Thymocytes increased significantly by day 21, followed by a significant improvement in mature T cell numbers in the periphery by day 35. This protective surge was temporary, receding by day 60. Double-negative 2 (DN2) proTs selectively increased thymocyte number, while DN3 proTs preferentially increased TECs and T cells in the spleen that persisted at day 60. These findings highlight the importance of the interaction between proTs and TECs in the proliferation and survival of TECs and that the maturation stage of proTs has unique effects on thymopoiesis and peripheral T cell recovery.

Serum miR-29a Is Upregulated in Acute Graft-versus-Host Disease and Activates Dendritic Cells through TLR Binding

Acute graft-versus-host disease (aGVHD) continues to be a frequent and devastating complication of allogeneic hematopoietic stem cell transplantation (HSCT), posing as a significant barrier against the widespread use of HSCTs as a curative modality. Recent studies suggested serum/plasma microRNAs (miRs) may predict aGVHD onset. However, little is known about the functional role of circulating miRs in aGVHD. In this article, we show in two independent cohorts that miR-29a expression is significantly upregulated in the serum of allogeneic HSCT patients at aGVHD onset compared with non-aGVHD patients. Serum miR-29a is also elevated as early as 2 wk before time of diagnosis of aGVHD compared with time-matched control subjects. We demonstrate novel functional significance of serum miR-29a by showing that miR-29a binds and activates dendritic cells via TLR7 and TLR8, resulting in the activation of the NF-κB pathway and secretion of proinflammatory cytokines TNF-α and IL-6. Treatment with locked nucleic acid anti-miR-29a significantly improved survival in a mouse model of aGVHD while retaining graft-versus-leukemia effects, unveiling a novel therapeutic target in aGVHD treatment or prevention.

Alarmins and Their Receptors as Modulators and Indicators of Alloimmune Responses

Cell damage and death releases alarmins, self-derived immunomodulatory molecules that recruit and activate the immune system. Unfortunately, numerous processes critical to the transplantation of allogeneic materials result in the destruction of donor and recipient cells and may trigger alarmin release. Alarmins, often described as damage-associated molecular patterns, together with exogenous pathogen-associated molecular patterns, are potent orchestrators of immune responses; however, the precise role that alarmins play in alloimmune responses remains relatively undefined. We examined evolving concepts regarding how alarmins affect solid organ and allogeneic hematopoietic cell transplantation outcomes and the mechanisms by which self molecules are released. We describe how, once released, alarmins may act alone or in conjunction with nonself materials to contribute to cytokine networks controlling alloimmune responses and their intensity. It is becoming recognized that this class of molecules has pleotropic functions, and certain alarmins can promote both inflammatory and regulatory responses in transplant models. Emerging evidence indicates that alarmins and their receptors may be promising transplantation biomarkers. Developing the therapeutic ability to support alarmin regulatory mechanisms and the predictive value of alarmin pathway biomarkers for early intervention may provide opportunities to benefit graft recipients.

Regulatory T cell expressed MyD88 is critical for prolongation of allograft survival

MyD88 signaling directly promotes T-cell survival and is required for optimal T-cell responses to pathogens. To examine the role of T-cell-intrinsic MyD88 signals in transplantation, we studied mice with targeted T-cell-specific MyD88 deletion. Contrary to expectations, we found that these mice were relatively resistant to prolongation of graft survival with anti-CD154 plus rapamycin in a class II-mismatched system. To specifically examine the role of MyD88 in Tregs, we created a Treg-specific MyD88-deficient mouse. Transplant studies in these animals replicated the findings observed with a global T-cell MyD88 knockout. Surprisingly, given the role of MyD88 in conventional T-cell survival, we found no defect in the survival of MyD88-deficient Tregs in vitro or in the transplant recipients and also observed intact cell homing and expression of Treg effector molecules. MyD88-deficient Tregs also fail to protect allogeneic bone marrow transplant recipients from chronic graft-versus-host disease, confirming the observations of defective regulation seen in a solid organ transplant system. Together, our data define MyD88 as having a divergent requirement for cell survival in non-Tregs and Tregs, and a yet-to-be defined survival-independent requirement for Treg function during the response to alloantigen.

IL-33 mediated expansion of host ST2+ Treg prior to allogeneic hematopoietic cell transplantation decreases macrophage and effector T cell activation reducing acute GVHD

Graft-versus-host disease (GVHD) is the leading complication and cause of mortality after allogeneic hematopoietic cell transplantation (allo-HCT). Recently, we reported that IL-33 released from tissue damaged during allo-HCT conditioning mediates pro-inflammatory responses by Teffector cells resulting in greater acute GVHD lethality and clinical symptoms in mice. However, IL-33 is a pleiotropic cytokine that mediates both pro-inflammatory and anti-inflammatory responses. We hypothesized that the beneficial effects mediated by IL-33 could be harnessed if IL-33 was present prior to inflammatory mediators released during conditioning. Here, we demonstrate that exogenous IL-33 given peri allo-HCT (days −10 to 4) to recipients of MHC-disparate allo-HCT asserts its immunoregulatory properties reduced GVHD lethality and clinical symptoms compared to non-treated controls. IL-33 treatment peri allo-HCT resulted in the expansion of recipient Treg and suppressive myeloid cells that persisted post irradiation. Host Treg depletion in C57Bl/6 FoxP3-DTR mice by diphtheria toxin given concurrently with peri allo-HCT IL-33 treatment accelerated GVHD symptoms and lethality compared to peri allo-HCT IL-33 treatment alone, demonstrating that host Treg were necessary for GVHD protection. Transfer of Treg deficient in ST2, the IL-33 receptor, afforded less GVHD protection than wild-type Treg. ST2+ Treg controlled macrophage activation and prevented accumulation of Teffector cells in GVHD target tissue. Thus, we demonstrate that peri allo-HCT IL-33 expanded and activated host Treg have potential as a therapeutic modality to prevent and treat GVHD.

Suppression of Tumorigenicity 2 (ST2) signaling is required for regulatory T cell control of Graft-vs. Host Disease

How IL-33-mediated signals impact on ST2-expressing regulatory T cell (Treg) expansion and regulatory functions is poorly understood. To establish the importance of direct IL-33 stimulation of Treg for control of alloimmune responses, we utilized a rodent model of graft-vs. host disease (GVHD) where C57BL/6 mice were irradiated and given a BALB/c bone marrow transplant (BMT) along with BALB/c CD4+ CD25+ Treg from st2+/+ or st2−/− mice at a 1:2 ratio with WT BALB/c CD3+ effector T cells. As expected, WT st2+/+ CD4+ CD25+ cells promoted full protection against GVHD with 90% of recipients receiving st2+/+ CD4+ CD25+ free of GVHD at Day 100 post-BMT. However, only 10% of mice that received st2−/− Treg achieved long-term survival (p=0.0017, st2+/+ v. st2−/−). Associated mechanistic studies revealed that Treg frequency was significantly reduced in recipients receiving st2−/− Treg compared to those receiving st2+/+ Treg. To define the signaling patterns IL-33 generates in Treg, fluorescence activated cell sorting was used to obtain ST2− or ST2+ Treg cells from the splenocytes of Foxp3 reporter mice and IL33 activated signaling downstream of ST2 was quantitated by phosphoflow cytometry. This analysis revealed that IL-33 signaling via ST2 on Treg activates both NF-κB and p38 MAPK. Yet, only IL-33-stimulated p38 MAPK, but not NF-kB, signaling was required for ST2+ Treg expansion. Our studies make two important observations regarding how IL-33 stimulation of Treg supports immune regulation. First, we demonstrate that IL-33 activates p38 MAPK to drive selective ST2+ Treg expansion. Second, we show that IL-33-mediated signals are critical to the capacity of Treg to control the alloimmune responses leading to GVHD.

The increase in thymopoiesis following T cell progenitor therapy is dependent upon the input population and continued interaction between developing T cells and the thymic microenvironment

The inclusion of in vitro derived T cell progenitor (proT) therapy with hematopoietic stem cell transplant (HSCT) aids in the recovery of the thymus damaged by total body irradiation and improves de novo thymopoiesis. To understand the interaction between proTs and the thymic microenvironment, wildtype (WT) mice were lethally irradiated and given T cell deficient donor (Rag1−/−) marrow along with in vitro generated proT from WT donors, limiting mature T cell development to infused proT. Donor proTs within the host thymus led to a significant increase in thymic epithelial cell (TEC) numbers by day 21 post-transplant, and increased actively cycling TECs as measured by Ki67 expression and BrdU uptake. However, that gain was temporary and lost by day 28, suggesting that continued signaling from proT cells is required to sustain TEC cycling and mass. We also find a significant improvement in total thymocyte number by day 21 followed by a significant increase in the total mature T cell number in the secondary lymphoid organs by day 28. This protective surge is also temporary, receding by day 60. In this time period, infused DN2 proTs selectively increased thymocyte number while DN3 proTs preferentially led to a greater TEC numbers. Interestingly, an exception in persistence occurs when DN3 proTs are used and the increase in mature T cells in the spleen persists at day 60. As a result of the lack of competition for thymic niches by cells from the Rag1−/− graft, a subpopulation of the infused proT persisted in the thymus in an immature state at day 60. These findings highlight the importance of the interaction between developing T cells and TECs in the proliferation and survival of these critical components of the thymic microenvironment.

Early in vivo signaling profiles in MUC1-specific CD4+ T cells responding to two different MUC1-targeting vaccines in two different microenvironments

Vaccines are beginning to be explored for as measures to prevent cancer. Since determining the efficacy of vaccines by evaluating disease outcome requires a long time, there is an urgent need for early predictive biomarkers. To this end, immunological endpoints that can be assessed weeks or months post-vaccination are currently being evaluated. However, when multiple vaccines are available, waiting for the development of humoral and cellular immunity could still cause delays, whereas early assessments would allow for a timely shift to more effective prevention modalities. Applying the phospho-flow technique to primary T cells, we examined the phosphorylation status of various proteins that shape the activation, proliferation, and differentiation of mucin 1 (MUC1)-specific CD4+ T cells within the first 24 hours post-immunization. It is known that a vaccine composed of a MUC1-derived peptide loaded on dendritic cells is more effective in eliciting T-cell responses than a vaccine including the same peptide plus an adjuvant. Both these vaccines stimulate T cells more effectively in wild-type (WT) than in MUC1-transgenic mice. We examined if the signaling events downstream of the TCR or linked to various proliferative and survival pathways, monitored in two different hosts as early as 3, 6, 12 and 24 hours post-immunization, could predict the differential potential of these two MUC1-targeting vaccines. The signaling signatures that we obtained primarily reflect differences between the vaccines rather than between the hosts. We demonstrate the feasibility of using a phospho-flow-based approach to evaluate the potential of a given vaccine to elicit a desired immune response.

Allograft outcomes in outbred mice

Inbreeding depression and lack of genetic diversity in inbred mice could mask unappreciated causes of graft failure or remove barriers to tolerance induction. To test these possibilities, we performed heart transplantation between outbred or inbred mice. Unlike untreated inbred mice in which all allografts were rejected acutely (6-16 days posttransplantation), untreated outbred mice had heterogeneous outcomes, with grafts failing early (<4 days posttransplantation), acutely (6-24 days) or undergoing chronic rejection (>75 days). Blocking T cell costimulation induced long-term graft acceptance in both inbred and outbred mice, but did not prevent the early graft failure observed in the latter. Further investigation of this early phenotype established that it is dependent on the donor, and not the recipient, being outbred and that it is characterized by hemorrhagic necrosis and neutrophilic vasculitis in the graft without preformed, high titer antidonor antibodies in the recipient. Complement or neutrophil depletion prevented early failure of outbred grafts, whereas transplanting CD73-deficient inbred hearts, which are highly susceptible to ischemia-reperfusion injury, recapitulated the early phenotype. Therefore, outbred mice could provide broader insight into donor and recipient determinants of allograft outcomes but their hybrid vigor and genetic diversity do not constitute a uniform barrier to tolerance induction.

Induction of antitumor immunity in vivo following delivery of a novel HPV-16 DNA vaccine encoding an E6/E7 fusion antigen

Human papillomavirus type 16 (HPV-16) infection is associated with a majority of cervical cancers and a significant proportion of head and neck cancers. Here, we describe a novel-engineered DNA vaccine that encodes a HPV-16 consensus E6/E7 fusion gene (pConE6E7) with the goal of increasing its antitumor cellular immunity. Compared to an early stage HPV-16 E7 DNA vaccine (pE7), this construct was up to five times more potent in driving E7-specific cellular immune responses. Prophylactic administration of this vaccine resulted in 100% protection against HPV E6 and E7-expressing tumors. Therapeutic studies indicated that vaccination with pConE6E7 prevented or delayed the growth of tumors. Moreover, immunization with pConE6E7 could also partially overcome immune tolerance in E6/E7 transgenic mice. Such DNA immunogens are interesting candidates for further study to investigate mechanisms of tumor immune rejection in vivo.

Increased viral load correlates with improved survival in HPV-16-associated tonsil carcinoma patients

CONCLUSION

Our results indicate that viral load may serve as an independent prognostic indicator for patients with HPV-16-associated squamous cell carcinoma of the tonsil.

OBJECTIVE

HPV-16 has gained increasing attention as a possible causative agent for squamous cell carcinoma of the tonsil. Recent reports have indicated that the viral load within the tumor, along with other factors, may be correlated to the patient survival. In this study, we sought to examine HPV-16 viral load as an independent prognostic indicator.

PATIENTS AND METHODS

DNA was extracted from 35 tonsil carcinoma samples and the viral load was determined by real-time PCR. The patients were divided into four groups according to HPV-16 viral load. The correlation between viral load and recurrence, disease-free survival, and overall survival was assessed.

RESULTS

We found that HPV-positive patients with the highest viral loads had improved overall and disease-free survival. Recurrences of squamous cell carcinoma were significantly less likely to occur with increasing viral load.

Locomotor hyperactivity and alterations in dopamine neurotransmission are associated with overexpression of A53T mutant human alpha-synuclein in mice

Genetic and biochemical abnormalities associated with alpha-synuclein are implicated in the etiology of Parkinson's disease (PD). In this study, altered locomotor behavior linked to the expression of mutant or wildtype human alpha-synuclein was investigated. A53T alpha-synuclein transgenic (A53T-tg) mice exhibited normal activity at 5 months of age; however, by 7 months, they developed marked hyperactivity that remained evident until 19 months. By contrast, mice expressing human wildtype or A30P mutant alpha-synuclein showed no locomotor alterations. Hyperactivity in A53T-tg mice was reversed by the D1 receptor antagonist SCH 23390. Furthermore, A53T-tg mice were supersensitive to the D1 receptor agonist SKF 81297 but not to the serotonin1B receptor agonist RU 24969. Hyperactivity in A53T-tg mice was also associated with increased D1 receptor expression in the substantia nigra and decreased dopamine transporter expression in the nucleus accumbens and striatum. Finally, striatal dopamine uptake measured by high-speed chronoamperometry was reduced by 40% in A53T-tg mice. Thus, expression of A53T mutant human alpha-synuclein in mice results in adult-onset hyperactivity associated with D1 receptor and dopamine transporter-mediated alterations in dopamine neurotransmission.