Prevention and treatment of acute GvHD

Systemic immunostimulation induces glucocorticoid-mediated thymic involution succeeded by rebound hyperplasia which is impaired in aged recipients

The thymus is the central organ involved with T-cell development and the production of naïve T cells. During normal aging, the thymus undergoes marked involution, reducing naïve T-cell output and resulting in a predominance of long-lived memory T cells in the periphery. Outside of aging, systemic stress responses that induce corticosteroids (CS), or other insults such as radiation exposure, induce thymocyte apoptosis, resulting in a transient acute thymic involution with subsequent recovery occurring after cessation of the stimulus. Despite the increasing utilization of immunostimulatory regimens in cancer, effects on the thymus and naïve T cell output have not been well characterized. Using both mouse and human systems, the thymic effects of systemic immunostimulatory regimens, such as high dose IL-2 (HD IL-2) with or without agonistic anti-CD40 mAbs and acute primary viral infection, were investigated. These regimens produced a marked acute thymic involution in mice, which correlated with elevated serum glucocorticoid levels and a diminishment of naïve T cells in the periphery. This effect was transient and followed with a rapid thymic "rebound" effect, in which an even greater quantity of thymocytes was observed compared to controls. Similar results were observed in humans, as patients receiving HD IL-2 treatment for cancer demonstrated significantly increased cortisol levels, accompanied by decreased peripheral blood naïve T cells and reduced T-cell receptor excision circles (TRECs), a marker indicative of recent thymic emigrants. Mice adrenalectomized prior to receiving immunotherapy or viral infection demonstrated protection from this glucocorticoid-mediated thymic involution, despite experiencing a substantially higher inflammatory cytokine response and increased immunopathology. Investigation into the effects of immunostimulation on middle aged (7-12 months) and advance aged (22-24 months) mice, which had already undergone significant thymic involution and had a diminished naïve T cell population in the periphery at baseline, revealed that even further involution was incurred. Thymic rebound hyperplasia, however, only occurred in young and middle-aged recipients, while advance aged not only lacked this rebound hyperplasia, but were entirely absent of any indication of thymic restoration. This coincided with prolonged deficits in naïve T cell numbers in advanced aged recipients, further skewing the already memory dominant T cell pool. These results demonstrate that, in both mice and humans, systemic immunostimulatory cancer therapies, as well as immune challenges like subacute viral infections, have the potential to induce profound, but transient, glucocorticoid-mediated thymic involution and substantially reduced thymic output, resulting in the reduction of peripheral naive T cells. This can then be followed by a marked rebound effect with naïve T cell restoration, events that were shown not to occur in advanced-aged mice.

Oncolytic virotherapy in hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a curative option for various hematologic malignancies. However, fatal complications, such as relapse and graft-versus-host disease (GVHD) hampered favorable HSCT outcomes. Cancer cells remained in the body following the conditioning regimen, or those contaminating the autologous graft can cause relapse. Although the relapse is much lesser in allogeneic HSCT, GVHD is still a life-threatening complication in this type of HSCT. Researchers are seeking various strategies to reduce relapse and GVHD in HSCT with minimum effects on the engraftment and immune-reconstitution. Oncolytic viruses (OVs) are emerging anti-cancer agents with promising results in battling solid tumors. OVs can selectively replicate in the malignant cells in which the antiviral immune responses have defected. Hence, they could be used as a purging agent to eradicate the tumoral contamination of autologous grafts with no damages to hematopoietic stem cells. Moreover, they have been shown to alleviate GVHD complications through modulating alloreactive T cell responses. Primary results promise using OVs as a strategy to reduce both relapse and GVHD in the HSCT without affecting hematologic and immunologic engraftment. Herein, we provide the latest findings in the field of OV therapy in HSCT and discuss their pros and cons.

Administration of FK506 from Late Stage of Disease Prolongs Survival of Human Prion-Inoculated Mice

Human prion diseases are etiologically categorized into three forms: sporadic, genetic, and infectious. Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common type of human prion disease that manifests as subacute progressive dementia. No effective therapy for sCJD is currently available. Potential therapeutic compounds are frequently tested in rodents infected with mouse-adapted prions that differ from human prions. However, therapeutic effect varies depending on the prion strain, which is one of the reasons why candidate compounds have shown little effect in sCJD patients. We previously reported that intraperitoneal administration of FK506 was able to prolong the survival of mice infected with a mouse-adapted prion by suppressing the accumulation of abnormal prion protein (PrP) and inhibiting the activation of microglia. In this study, we tested oral administration of FK506 in knock-in mice expressing chimeric human prion protein (KiChM) that were infected with sCJD to determine if this compound is also effective against a clinically relevant human prion, i.e., one that has not been adapted to mice. Treatment with FK506, started either just before or just after disease onset, suppressed typical sCJD pathology (gliosis) and slightly but significantly prolonged the survival of sCJD-inoculated mice. It would be worthwhile to conduct a clinical trial using FK506, which has been safety-approved and is widely used as a mild immunosuppressant.

Epidermal growth factor stimulates exosomal microRNA-21 derived from mesenchymal stem cells to ameliorate aGVHD by modulating regulatory T cells

Regulatory T cells (Tregs), a subset of CD4⁺ T cells, may exert inhibitory effects on alloimmune responses including acute graft-versus-host disease (aGVHD), and several microRNAs are implicated in the pathophysiological process of GVHD. Therefore, we aimed in the present study to characterize the functional relevance of epidermal growth factor (EGF)-stimulated microRNA-21 (miR-21) in regulating bone marrow-derived mesenchymal stem cells (BMSCs) in a mouse model of aGVHD. We first isolated and cultured BMSCs and Tregs. Then, we examined effects of miR-21 knockdown or overexpression and EGF on cell activities of BMSCs and the expression of PTEN, Foxp3, AKT phosphorylation, and extent of c-jun phosphorylation by gain- and loss-of-function approaches. The results showed that miR-21 promoted the proliferation, invasion, and migration of BMSCs. Furthermore, miR-21 in BMSCs-derived exosomes inhibited PTEN, but enhanced AKT phosphorylation and Foxp3 expression in Tregs. In addition, EGF enhanced c-jun phosphorylation to elevate the miR-21 expression. Furthermore, EGF significantly increased the efficacy of BMSCs in a mouse model of aGVHD, manifesting in reduced IFN-γ expression and lesser organ damage. Moreover, EGF treatment promoted the Foxp3 expression of Tregs in BMSCs-treated aGVHD mice. Taken together, EGF induced the BMSCs-derived exosomal miR-21 expression, which enhanced Foxp3 expression in Tregs, thereby improving the therapeutic effect of BMSCs on aGVHD.

Composite biomarker panel for prediction of severity and diagnosis of acute GVHD with T-cell-depleted allogeneic stem cell transplants-single centre pilot study

AIMS

Acute graft-versus-host disease (aGVHD) is a leading cause of morbidity and mortality following allogeneic haematopoietic stem cell transplantation (HSCT). The aim of this study was to evaluate the clinical utility of a composite biomarker panel to help identify individuals at risk of developing aGVHD, and to help predict and differentiate between severity of aGVHD following T-cell-depleted allogeneic HSCT.

METHODS

We retrospectively analysed our cohort of biopsy confirmed patients with aGVHD, who underwent T-cell-depleted HSCT and matched them with negative controls without any evidence of aGVHD. Post-transplant serum samples on days 0 and 7 and at onset of aGVHD were analysed for elafin, regenerating islet-derived 3-α, soluble tumour necrosis factor receptor-1, soluble interleukin-2 receptor-α and hepatocyte growth factor. Biomarker data were combined as composite panels A-F (table 2) using logistic regression analysis. Receiver operating characteristic analysis was performed to study sensitivity and specificity of the composite panels.

RESULTS

Our composite biomarker panels significantly differentiated between aGVHD and no GVHD patients at time of onset (panel E) and reliably predicted severity of GVHD grades at days 0 and 7 post-transplant (panels B and D). The area under the curve for the composite panel at time of onset was 0.65 with specificity, sensitivity, positive and negative predictive values of 100%, 55.6%, 100% and 78.9%, respectively (p=0.03).

CONCLUSIONS

This pilot data support the usefulness of these composite biomarker panels in the prediction of severity and diagnosis of aGVHD in patients undergoing T-cell-depleted reduced intensity allogeneic HSCT.

Combining therapeutic antibodies using basiliximab and etanercept for severe steroid-refractory acute graft-versus-host disease: A multi-center prospective study

Acute graft versus host disease (aGVHD) remains a major problem after allogeneic hematopoietic stem cell transplantation. Standard frontline therapy for aGVHD involves corticosteroids. However, fewer than half of patients have a lasting complete response. The long-term mortality rate of steroid-refractory aGVHD (SR-aGVHD) remains around 70%. To date, no consensus has been reached regarding the optimal salvage treatment for SR-aGVHD. We performed the first prospective, multi-center clinical trial to assess the efficacy and safety of a novel approach to treat severe (grades III-IV) SR-aGVHD with the combination of basiliximab and etanercept. Sixty-five patients with severe SR-aGVHD from six centers were included. The median number of basiliximab infusions was 4 (range 2-11) and of etanercept was 9 (range 2-12). At day 28 after starting the combination treatment, overall response (complete and partial response: CR+PR) to second-line treatment was 90.8% with 75.4% being CR. The incidences of CR per organ were 100%, 73.8%, and 79.7% for skin, liver, and gut involvement, respectively. Patients >30-y old (p = 0.043, RR = 3.169), development of grades III-IV liver aGVHD (p = 0.007, RR = 5.034) and cytomegalovirus (CMV) reactivation (p = 0.035, RR = 4.02) were independent predictors for incomplete response. Combined treatment with basiliximab and etanercept resulted in improved CR to visceral aGVHD and significantly superior 2-y overall survival (54.7% vs. 14.8%, p <0.001) compared with classical salvage treatments. Our data suggest that the combination of basiliximab and etanercept may constitute a promising new treatment option for SR-aGVHD.

Unraveling mechanisms of mesenchymal stromal cell-mediated immunomodulation through patient monitoring and product characterization

Mesenchymal stromal cells (MSCs) are increasingly used in the treatment of a variety of clinical conditions and to modulate immune responses in conditions related to auto-/alloimmunity, including graft-versus-host disease (GvHD). Although pilot data are promising, treatment responses have been highly variable, and further development of this as a therapeutic modality depends on increased insight into the properties of clinical MSC products and on understanding the mechanisms underlying responses in patients. Here we review the mechanisms that possibly underlie the capacity of MSCs to treat auto-/alloimmunity, and describe how patient monitoring can help to identify the in vivo mechanisms of action in the treatment of GvHD. Since MSCs used in the clinic originate from various donors and from a heterogeneous population of cells, we will also discuss recent insights into MSC heterogeneity and their implications for clinical MSC products. Finally, we describe a framework to improve our understanding of the efficacy and working mechanism of MSCs, which involves patient monitoring and more extensive characterization of the heterogeneity within and between different MSC preparations.

Neural and mesenchymal stem cells in animal models of Huntington's disease: past experiences and future challenges

Huntington's disease (HD) is an inherited disease that causes progressive nerve cell degeneration. It is triggered by a mutation in the HTT gene that strongly influences functional abilities and usually results in movement, cognitive and psychiatric disorders. HD is incurable, although treatments are available to help manage symptoms and to delay the physical, mental and behavioral declines associated with the condition. Stem cells are the essential building blocks of life, and play a crucial role in the genesis and development of all higher organisms. Ablative surgical procedures and fetal tissue cell transplantation, which are still experimental, demonstrate low rates of recovery in HD patients. Due to neuronal cell death caused by accumulation of the mutated huntingtin (mHTT) protein, it is unlikely that such brain damage can be treated solely by drug-based therapies. Stem cell-based therapies are important in order to reconstruct damaged brain areas in HD patients. These therapies have a dual role: stem cell paracrine action, stimulating local cell survival, and brain tissue regeneration through the production of new neurons from the intrinsic and likely from donor stem cells. This review summarizes current knowledge on neural stem/progenitor cell and mesenchymal stem cell transplantation, which has been carried out in several animal models of HD, discussing cell distribution, survival and differentiation after transplantation, as well as functional recovery and anatomic improvements associated with these approaches. We also discuss the usefulness of this information for future preclinical and clinical studies in HD.

The Immunomodulatory and Therapeutic Effects of Mesenchymal Stromal Cells for Acute Lung Injury and Sepsis

It is increasingly recognized that immunomodulation represents an important mechanism underlying the benefits of many stem cell therapies, rather than the classical paradigm of transdifferentiation and cell replacement. In the former paradigm, the beneficial effects of cell therapy result from paracrine mechanism(s) and/or cell-cell interaction as opposed to direct engraftment and repair of diseased tissue and/or dysfunctional organs. Depending on the cell type used, components of the secretome, including microRNA (miRNA) and extracellular vesicles, may be able to either activate or suppress the immune system even without direct immune cell contact. Mesenchymal stromal cells (MSCs), also referred to as mesenchymal stem cells, are found not only in the bone marrow, but also in a wide variety of organs and tissues. In addition to any direct stem cell activities, MSCs were the first stem cells recognized to modulate immune response, and therefore they will be the focus of this review. Specifically, MSCs appear to be able to effectively attenuate acute and protracted inflammation via interactions with components of both innate and adaptive immune systems. To date, this capacity has been exploited in a large number of preclinical studies and MSC immunomodulatory therapy has been attempted with various degrees of success in a relatively large number of clinical trials. Here, we will explore the various mechanism employed by MSCs to effect immunosuppression as well as review the current status of its use to treat excessive inflammation in the context of acute lung injury (ALI) and sepsis in both preclinical and clinical settings.

The potential of cytotherapeutics in hematologic reconstitution and in the treatment and prophylaxis of graft-versus-host disease. Chapter I: current practice and remaining unmet medical needs

Hematopoietic stem cell transplantation is a life-saving treatment for inherited anemias, immunodeficiencies or hematologic malignancies. When using partially HLA-matched allografts, a major complication is graft-versus-host disease (GvHD). The ideal attributes of a transformational new GvHD treatment include improved survival, decreased corticosteroids, decreased antifungals, improved quality of life through decreased infections, reduced number of hospital stay days, reduced risks of developing chronic GvHD impact on lower GI tract and liver, prophylactic benefits and decreased GvHD relapses, but, in the case of cancer, without negatively impacting beneficial graft-versus-tumor effects. The current practice of hematopoietic stem cell transplantation, its incidence and its unmet medical needs are reviewed here and discussed.

Graft versus host disease: New insights into A2A receptor agonist therapy

Allogeneic transplantation can cure many disorders, including sickle cell disease, chronic granulomatous disease (CGD), severe combined immunodeficiency (SCID) and many types of cancers. However, there are several associated risks that can result in severe immunological reactions and, in some cases, death. Much of this morbidity is related to graft versus host disease (GVHD) [1]. GVHD is an immune mediated reaction in which donor T cells recognize the host as antigenically foreign, causing donor T cells to expand and attack host tissues. The current method of treating recent transplant patients with immunosuppressants to prevent this reaction has met with only partial success, emphasizing a need for new methods of GVHD treatment and prevention. Recently, a novel strategy has emerged targeting adenosine A_2A receptors (A_2AR) through the use of adenosine agonists. These agonists have been shown in vitro to increase the TGFβ-induced generation of FoxP3⁺ regulatory T cells (T_regs) and in vivo to improve weight gain and mortality as well as inhibit the release of pro-inflammatory cytokines in GVHD murine models [2,3]. Positive results involving A_2AR agonists in vitro and in vivo are promising, suggesting that A_2AR agonists should be a part of the management of clinical GvHD.

Pain Management for Children during Bone Marrow and Stem Cell Transplantation

Pain management for children during bone marrow and stem cell transplantation is a significant clinical challenge for the health care team. Pain management strategies vary by institution. This paper reports on the use of a pediatric pain management service and patient- and caregiver-controlled analgesia for children undergoing transplant. This 2-year retrospective chart review examined the pain management practices and outcomes of children undergoing bone marrow and stem cell transplants in a large urban teaching hospital during 2008 and 2009. We concluded that patient- and caregiver-controlled analgesia is a well-tolerated modality for pain control during hospitalization for transplantation at this institution.

Human mesenchymal stem cells suppress donor CD4(+) T cell proliferation and reduce pathology in a humanized mouse model of acute graft-versus-host disease

Acute graft-versus-host disease (aGVHD) is a life-threatening complication following allogeneic haematopoietic stem cell transplantation (HSCT), occurring in up to 30-50% of patients who receive human leucocyte antigen (HLA)-matched sibling transplants. Current therapies for steroid refractory aGVHD are limited, with the prognosis of patients suboptimal. Mesenchymal stem or stromal cells (MSC), a heterogeneous cell population present in many tissues, display potent immunomodulatory abilities. Autologous and allogeneic ex-vivo expanded human MSC have been utilized to treat aGVHD with promising results, but the mechanisms of therapeutic action remain unclear. Here a robust humanized mouse model of aGVHD based on delivery of human peripheral blood mononuclear cells (PBMC) to non-obese diabetic (NOD)-severe combined immunodeficient (SCID) interleukin (IL)-2rγ(null) (NSG) mice was developed that allowed the exploration of the role of MSC in cell therapy. MSC therapy resulted in the reduction of liver and gut pathology and significantly increased survival. Protection was dependent upon the timing of MSC therapy, with conventional MSC proving effective only after delayed administration. In contrast, interferon (IFN)-γ-stimulated MSC were effective when delivered with PBMC. The beneficial effect of MSC therapy in this model was not due to the inhibition of donor PBMC chimerism, as CD45(+) and T cells engrafted successfully in this model. MSC therapy did not induce donor T cell anergy, FoxP3(+) T regulatory cells or cause PBMC apoptosis in this model; however, it was associated with the direct inhibition of donor CD4(+) T cell proliferation and reduction of human tumour necrosis factor-α in serum.

Infliximab for steroid refractory or dependent gastrointestinal acute graft-versus-host disease in children after allogeneic hematopoietic stem cell transplantation

aGVHD of the GI tract is common after allogeneic HSCT. Corticosteroids are the mainstay of treatment. Recent data suggest infliximab might be beneficial for steroid refractory aGVHD. We reviewed our experience in 10 pediatric patients who developed severe steroid refractory aGVHD (stage 3, n = 6; stage 4, n = 4), after an allogeneic matched unrelated HSCT for various hematological diseases (leukemia, n = 7; thalassemia, n = 3). The median age was 9.5 yr (range, 0.8-18.5 yr). All patients received 10 mg/kg infliximab weekly for 3-4 doses. Eight patients had CR and two had partial response. None of the patients developed therapy-related adverse effects. All patients developed infections subsequently, which may or may not be related to infliximab. Five patients developed chronic GVHD (cGVHD) (four severe, one mild). Six patients died at 66-1451 days post-transplant, from infection (n = 3), aGVHD (n = 1), lung cGVHD (n = 1), or idiopathic pneumonia (n = 1). Four patients were alive at 238-924 days post-transplant, all of whom had an increase in BMI by six months post-transplant. In conclusion, infliximab is well tolerated and appears effective in children with steroid refractory or dependent GI aGVHD. Infection is common and mortality remains high.

Clinical applications of mesenchymal stem cells

Mesenchymal stem cells (MSC) have generated a great amount of enthusiasm over the past decade as a novel therapeutic paradigm for a variety of diseases. Currently, MSC based clinical trials have been conducted for at least 12 kinds of pathological conditions, with many completed trials demonstrating the safety and efficacy. This review provides an overview of the recent clinical findings related to MSC therapeutic effects. Roles of MSCs in clinical trials conducted to treat graft-versus-host-disease (GVHD) and cardiovascular diseases are highlighted. Clinical application of MSC are mainly attributed to their important four biological properties- the ability to home to sites of inflammation following tissue injury when injected intravenously; to differentiate into various cell types; to secrete multiple bioactive molecules capable of stimulating recovery of injured cells and inhibiting inflammation and to perform immunomodulatory functions. Here, we will discuss these four properties. Moreover, the issues surrounding clinical grade MSCs and principles for MSC therapeutic approaches are also addressed on the transition of MSCs therapy from bench side to bedside.

In vivo depletion of lymphotoxin-alpha expressing lymphocytes inhibits xenogeneic graft-versus-host-disease

Graft-versus-host disease (GVHD) is a major barrier to successful allogeneic hematopoietic cell transplantation and is largely mediated by activated donor lymphocytes. Lymphotoxin (LT)-α is expressed by subsets of activated T and B cells, and studies in preclinical models demonstrated that targeted depletion of these cells with a mouse anti-LT-α monoclonal antibody (mAb) was efficacious in inhibiting inflammation and autoimmune disease. Here we demonstrate that LT-α is also upregulated on activated human donor lymphocytes in a xenogeneic model of GVHD and targeted depletion of these donor cells ameliorated GVHD. A depleting humanized anti-LT-α mAb, designated MLTA3698A, was generated that specifically binds to LT-α in both the soluble and membrane-bound forms, and elicits antibody-dependent cellular cytotoxicity (ADCC) activity in vitro. Using a human peripheral blood mononuclear cell transplanted SCID (Hu-SCID) mouse model of GVHD, the anti-human LT-α mAb specifically depleted activated LT-expressing human donor T and B cells, resulting in prolonged survival of the mice. A mutation in the Fc region, rendering the mAb incapable of mediating ADCC, abolished all in vitro and in vivo effects. These data support a role for using a depleting anti-LT-α antibody in treating immune diseases such as GVHD and autoimmune diseases.

Association of HLA-G low expressor genotype with severe acute graft-versus-host disease after sibling bone marrow transplantation

Background: Human leukocyte antigen-G (HLA-G) molecules play a prominent role in immune tolerance. Structurally similar to their classical HLA homologs, they are distinct by having high rate of polymorphism in the non-coding regions including a functionally relevant 14-base pair (bp) insertion/deletion (Ins/Del) allele in the 3′ untranslated region (3′UTR), rarely examined in a hematopoietic stem cell transplantation (HSCT) setting. Here, we analyzed the potential impact of HLA-G Ins/Del dimorphism on the incidence of acute graft-versus-host disease (aGvHD), transplant-related mortality (TRM), overall survival (OS), and incidence of relapse after HSCT using bone marrow (BM) as stem cell source from HLA-matched donors. Methods: One hundred fifty-seven sibling pairs, who had undergone HSCT, were studied for the distribution of the HLA-G 14 bp Ins/Del polymorphism using a polymerase chain reaction (PCR)-based technique. Potential genetic association with the incidence of aGvHD, TRM, and OS was analyzed by monovariate and multivariate analyses. Results: Monovariate analysis showed that the homozygous state for the 14-bp Ins allele is a risk factor for severe aGvHD (grade III and IV; P = 0.008), confirmed subsequently by multivariate analysis [hazard ratio (HR) = 3.5; 95% confidence interval (95%CI) = 1.3–9.5; P = 0.012]. We did not find any association between HLA-G polymorphism and the other studied complications. Conclusion: Our data suggest that the HLA-G low expressor 14 bp Ins allele constitutes a risk factor for the incidence of severe aGvHD in patients who received BM as stem cell source.

Amelioration of acute graft-versus-host disease by adoptive transfer of ex vivo expanded human cord blood CD4+CD25+ forkhead box protein 3+ regulatory T cells is associated with the polarization of Treg/Th17 balance in a mouse model

BACKGROUND

Human cord blood (CB) is a superior source of regulatory T cells (Tregs) compared with peripheral blood. Initial studies have shown that CB-derived Tregs can be effectively expanded ex vivo. However, in vitro suppressor activity of expanded CB-Tregs and their efficacy in the prevention of acute graft-versus-host disease (aGVHD) in vivo are poorly understood.

STUDY DESIGN AND METHODS

In vitro, human CB CD4+CD25+ T cells expanded with anti-CD3/CD28 beads plus interleukin (IL)-2 and the phenotypes, expression of cytokines, and suppression of expanded cells were analyzed after two cycles of stimulation. In vivo, the addition of human CB-Tregs was transferred in the major histocompatibility complex-mismatched aGVHD mouse model. Survival, body weight, GVHD scoring, histopathologic specimens, serum cytokines, and Th subsets were analyzed in CB-Treg-treated mice and untreated controls.

RESULTS

After being expanded ex vivo, human CB-derived Tregs with potent suppressor function could meet clinical demands. Up to 85% of mice with CB-Tregs treatment survived beyond Day 63 after bone marrow transplantation; however, all aGVHD mice died within 18 days. In the serum of the CB-Treg-treated mice, the production of transforming growth factor-β increased continuously, as opposed to IL-17, which decreased quickly. Consistent with the changes of cytokines, the percentage of mouse CD4+ forkhead box protein 3+ Tregs increased while that of Th17 cells decreased.

CONCLUSION

Ex vivo expanded human CB-Tregs significantly prevented allogeneic aGVHD in vivo by modulating various cytokine secretion and polarizing the Treg/Th17 balance toward Treg, which suggests the potential use of expanded CB-Tregs as a therapeutic approach for GVHD.

Brazilian green propolis and its constituent, Artepillin C inhibits allogeneic activated human CD4 T cells expansion and activation

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis has long been used as a popular folk medicine by various ethnic groups due to its wide spectrum of alleged biological and pharmaceutical properties including anti-microbial, anti-cancer and anti-inflammatory functions. All these can be linked to the modulation of immune function. Therefore, it will be relevant for us to find out whether there is any novel compound that can account for such action and the mechanism involved.

AIM OF THE STUDY

We investigated the immune modulating effect of Brazilian green propolis (PBrazil) and its constituent Artepillin C (Art-C) by using mixed leukocytes reaction.

MATERIALS AND METHODS

The cytotoxic effect of Art-C on non-tumorigenic human liver cell line miHA and non-tumorigenic human kidney cell line HK-2 as well as human peripheral blood mononuclear cells (PBMCs) were measured by XTT cell proliferation assay. The effect of PBrazil and Art-C on T cell proliferation and activation were determined by using carboxyfluorescein succinimidyl ester (CFSE) and by CD25 expression, respectively. Cytokines including tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), interleukins such as IL-2, IL-17 were measured by intracellular cytokine staining and IL-10 was measured by ELISA. The effect of PBrazil and Art-C on regulatory T cells (Treg) induction was determined by the Foxp3 expression. The apoptotic effect of these compounds on CFSE labeled alloreactive T cells was measured by using Annexin V.

RESULTS

Using mixed leukocytes reaction we demonstrated for the first time that both Art-C and PBrazil significantly inhibited the alloreactive CD4 T cell proliferation, activation, and suppressed the expressions of IL-2, IFN-γ and IL-17 in these alloreactive CD4 T cells. The inhibitions of Art-C and PBrazil on CD4 T cells were not due to direct cytotoxic effect on PBMC or inducing regulatory T cells differentiation. Both Art-C and PBrazil were found to selectively induce apoptosis in proliferating T cells. The anti-proliferative effect of Art-C and PBrazil were reversible and were also applied to the activated T cells.

CONCLUSIONS

In conclusion, our results indicated that Art-C and PBrazil can suppress alloreactive CD4 T cell responses in vitro, suggesting that Art-C could be used as a potential immunosuppressant, either solely or as adjunct agent in treating graft versus host disease.

Mesenchymal stromal cells for treatment of steroid-refractory GvHD: a review of the literature and two pediatric cases

Severe acute graft versus host disease (GvHD) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation. Human mesenchymal stromal cells (MSCs) play an important role in endogenous tissue repair and possess strong immune-modulatory properties making them a promising tool for the treatment of steroid-refractory GvHD. To date, a few reports exist on the use of MSCs in treatment of GvHD in children indicating that children tend to respond better than adults, albeit with heterogeneous results.

We here present a review of the literature and the clinical course of two instructive pediatric patients with acute steroid-refractory GvHD after haploidentical stem cell transplantation, which exemplify the beneficial effects of third-party transplanted MSCs in treatment of acute steroid-refractory GvHD. Moreover, we provide a meta-analysis of clinical studies addressing the outcome of patients with steroid-refractory GvHD and treatment with MSCs in adults and in children (n = 183; 122 adults, 61 children). Our meta-analysis demonstrates that the overall response-rate is high (73.8%) and confirms, for the first time, that children indeed respond better to treatment of GvHD with MSCs than adults (complete response 57.4% vs. 45.1%, respectively).

These data emphasize the significance of this therapeutic approach especially in children and indicate that future prospective studies are needed to assess the reasons for the observed differential response-rates in pediatric and adult patients.

Narrowband ultraviolet B phototherapy for the treatment of steroid-refractory and steroid-dependent acute graft-versus-host disease of the skin

BACKGROUND

Acute graft-versus-host disease (aGvHD) is a common complication of allogeneic stem cell transplantation. It is usually treated with high doses of corticosteroids and other immunosuppressive agents. When cutaneous features are predominant, narrowband ultraviolet B (NB-UVB) phototherapy may be an attractive option for its steroid-sparing effect.

OBJECTIVE

We sought to examine the clinical efficacy of NB-UVB in the treatment of steroid-refractory and steroid-dependent cutaneous aGvHD.

METHODS

We conducted a retrospective chart review of patients with steroid-refractory and steroid-dependent aGvHD, who received NB-UVB between 2005 and 2009 at our institution.

RESULTS

We identified 14 patients with aGvHD treated with NB-UVB between 2005 and 2009. The median number of treatments was 15, administered over a median of 43 days. Eight of 14 patients (57%) achieved a complete response at the end of treatment; an additional 3 patients (21%) achieved a partial response; and 3 patients (21%) showed no improvement at the time when phototherapy was discontinued (nonresponders). Four patients developed chronic graft-versus-host disease (GvHD). Three of the 8 complete responders remained free of GvHD at 6 months' follow-up.

LIMITATIONS

The rarity of steroid-refractory aGvHD limited the study to a small number of participants. Because GvHD is variable in its presentation and course, and life-threatening in many cases, large controlled prospective trials for potential therapies are difficult.

CONCLUSIONS

NB-UVB is a viable option for the treatment of steroid-refractory and steroid-dependent aGvHD of the skin.

Immunoregulation of GVHD by triggering the innate immune system with CpG

Stimulation of Toll-like receptors by oligodeoxynucleotide sequences containing a CpG motif provides signals capable of triggering the innate and adaptive immune systems, thereby leading either to stimulation or suppression of immunoreactivities. Similar immunoregulatory capabilities are necessary for achieving the fine balance between engraftment and graft-versus-host disease required in the setup of allogeneic cell therapy. Ligation of CpG to its Toll-like receptors can be accomplished by treatment of the host or pretransplant treatment of the donor in vivo. These different strategies are presented in this review, which summarizes the attempts to maximize beneficial alloreactivity against malignant or other undesirable host cells, while controlling graft-versus-host disease.

Extracorporeal photopheresis attenuates murine graft-versus-host disease via bone marrow-derived interleukin-10 and preserves responses to dendritic cell vaccination

Extracorporeal photopheresis (ECP) is emerging as a therapy for graft-versus-host-disease (GVHD), but the full mechanism of action and the impact on immunity have not been fully established. After murine minor histocompatibility antigen-mismatched bone marrow (BM) transplantation (allo-BMT), coinfusion of ECP-treated splenocytes with T cell-replete BM attenuated GVHD irrespective of the donor strain of the ECP-treated splenocytes, and was associated with increased numbers of regulatory T cells. Coculture of myeloid dendritic cells (DCs) with ECP-treated splenocytes resulted in increased interleukin (IL)-10 production after submaximal stimulation with lipopolysaccharide. Furthermore, male myeloid DCs exposed to ECP-treated splenocytes were less potent at inducing CD8(+) HY responses when used as a vaccine in vivo. The efficacy of ECP-treated splenocytes was enhanced when administered just before delayed donor lymphocyte infusion following T cell-depleted allo-BMT, allowing for the administration of sufficient numbers of T cells to respond to myeloid DC vaccination in the absence of a thymus. Finally, the therapeutic effect of ECP-treated splenocytes was lost in recipients of IL-10-deficient BM. We demonstrate that ECP-treated splenocytes attenuate GVHD irrespective of the source of ECP-treated cells via a mechanism that likely involves modulation of DCs and requires IL-10 produced by BM-derived cells. Importantly, the attenuation of GVHD by ECP-treated splenocytes permits donor lymphocyte infusion-dependent responses to DC vaccines after allo-BMT.

CP-690550, a Janus kinase inhibitor, suppresses CD4+ T-cell-mediated acute graft-versus-host disease by inhibiting the interferon-γ pathway

BACKGROUND

Acute graft-versus-host disease (GVHD) is a critical obstacle to bone marrow transplantation. Although numerous studies have described immunosuppression protocols to mitigate acute GVHD, the need still exists for a more efficient immunosuppressant with fewer side effects. Here, we evaluated the protective effect of CP-690550, a newly developed Janus kinase inhibitor, in an acute GVHD model.

METHODS

CP-690550 was chemically synthesized. Acute GVHD was induced through the transfer of parent B6 (H-2) bone marrow and CD4 T cells into lethally irradiated (B6×bm12)F1 (H-2) mice. RESULTS.: CP-690550 treatments confined to days -3 to 11 of GVHD induction provided full protection against allogeneic, acute GVHD-related lethality and histopathology. An analysis of the initial donor-derived CD4 T-cell responses revealed that the inhibitory effects of CP-690550 were largely related to the suppression of donor CD4 T-cell-mediated interferon (IFN)-γ production. Enhanced inhibition of T helper 1 cell differentiation, rather than the inhibition of allogeneic CD4 T-cell proliferation or T helper 17 cell differentiation, was also confirmed in allogeneic mixed lymphocyte reactions. Because lethality was considerably delayed by the systemic blockade of IFN-γ, the principal protective effect of CP-690550 occurred through the modulation of IFN-γ production.

CONCLUSION

The targeting of Janus kinase with a sensitive and specific inhibitor, CP-690550, conferred effective protection from acute GVHD induced by a semiallogeneic major histocompatibility complex class II-disparate combination. Protection from acute GVHD was largely mediated by the inhibition of IFN-γ production.

Immunoregulatory gene polymorphisms and graft-versus-host disease

Graft-versus-host disease (GVHD) remains a significant complication that greatly enhances morbidity and mortality associated with hematopoietic stem cell transplantation. Key immunoregulatory molecules have been implicated in the pathogenesis of GVHD, but the mechanisms by which these molecules affect the incidence and severity of GVHD have not been fully elucidated. The effects of genetic polymorphisms in immunoregulatory molecules, including cytokines, costimulatory and adhesion molecules, pharmacogenes and growth factors, have been shown to play a central role in GVHD. The results of these polymorphism studies contribute to the identification of predictive risk factors for GVHD based on individual polymorphism makeup. This review summarizes investigations of genetic polymorphisms in immunoregulatory molecules significantly associated with GVHD over the last 5 years.

A high risk of life-threatening infectious complications in mycophenolate mofetil treatment for acute or chronic graft-versus-host disease

We describe herein the clinical courses and outcomes of 26 patients who received oral mycophenolate mofetil (MMF) for the treatment of steroid-resistant refractory or steroid-dependent acute or chronic graft-versus-host disease (GVHD) in a single institution. In most cases, 1,500 mg/day of MMF is a median dose (range 500-3,000 mg/day) and administered for 116.5 days (range 9-584 days) along with calcineurin inhibitors and steroids. Although 20 patients (77%) showed rapid improvement of GVHD symptoms, of 15 patients, 13 (87%) showed acute GVHD; of 11 patients, 7 (64%) showed chronic GVHD; most patients (54%) experienced infection during MMF administration, including 5 cases with life-threatening infection. Positive cytomegalovirus (CMV) antigenemia was also observed in 19 patients (73%), but no patients developed CMV infection. Within the median follow-up of 12.5 months (range 0.5-67 months), 10 patients (39%) died. This small study demonstrates that MMF offers an alternative tool for rescuing steroid-refractory or steroid-dependent GVHD, but increases the risk of developing life-threatening infection.

Intra-arterial methylprednisolone infusion in treatment-resistant graft-versus-host disease

Acute graft-versus-host disease (GVHD) is a potentially fatal complication following allogeneic hematopoietic stem cell transplant. Standard primary therapy for acute GVHD includes systemic steroids, often in combination with other agents. Unfortunately, primary treatment failure is common and carries a high mortality. There is no generally accepted secondary therapy for acute GVHD. Although few data on localized therapy for GVHD have been published, intra-arterial injection of high-dose corticosteroids may be a viable option. We treated 11 patients with steroid-resistant GVHD using a single administration of intra-arterial high-dose methylprednisolone. Three patients (27%) died periprocedurally. Four patients (36%) had a partial response to intra-arterial treatment and were discharged on total parenteral nutrition and oral medication. Four patients (36%) had a complete response and were discharged on oral diet and oral medication. No immediate treatment or procedure-related complications were noted. Twenty-seven percent of patients survived long-term. Our preliminary results suggest that regional intra-arterial treatment of steroid-resistant GVHD is a safe and potentially viable secondary therapy in primary treatment-resistant GVHD.

Improved T and B cell recovery by the transfer of slowly dividing human hematopoietic stem cells

Human hematopoietic stem cells giving rise to long term initiating cells in vitro are enriched in a CD34(+) slow dividing fraction (SDF). Here, we tested reconstitution and multilineage differentiation of this CD34(+) SDF in NOD/SCID mice. In the bone marrow a slightly higher percentage of human hematopoietic progenitors were recovered after the transfer of the SDF compared to the fast dividing fraction. Instead, T cell maturation in the rudimentary thymus and lymph node repopulation was only initiated by the SDF. The capacity of the SDF to differentiate and mature in the patients' thymus could provide an advantage in immunocompetence recovery.

Adoptive therapy by transfusing expanded donor murine natural killer T cells can suppress acute graft-versus-host disease in allogeneic bone marrow transplantation

BACKGROUND

Invariant natural killer T cells (iNKT cells) may suppress graft-versus-host disease (GVHD) after allogeneic transplantation. The purpose of this study was to investigate the therapeutic potential of iNKT cells from major histocompatibility complex (MHC)-mismatched donors for preventing GVHD after allogeneic bone marrow transplantation (BMT).

STUDY DESIGN AND METHODS

In vitro, mouse iNKT cells were expanded with alpha-galactosylceramide and interleukin (IL)-2 treatment. In the NKT-treated group, lethally irradiated DBA/2(H-2K(d)) mice were adoptively transferred with expanded iNKT, bone marrow (BM), and spleen cells (SCs) from C57BL/6 (H-2K(b)) mice. Recipients in the control group were transferred only BM and SCs. The two groups were compared in survival, weight, histopathologic specimens, and serum cytokine analysis.

RESULTS

In the iNKT-treated group, 80% of mice survived past Day 60 after BMT, but all died within 38 days in the control group. The mice treated with iNKT did not exhibit signs of GVHD after Day 42 except for a change in fur color. There were higher IL-4 levels by Day 7 in serum of mice that received iNKT compared to those without iNKT treatment, while the interferon-gamma levels showed no significant difference between two groups. Levels of IL-2 and IL-5 increased by Day 21 only in iNKT-treated mice.

CONCLUSION

The results suggest that donor iNKT cells could alleviate GVHD symptoms and prolong survival after MHC-mismatched allogeneic BMT, which may be associated with the maintenance in IL-4 levels. These findings indicate that the therapy based on iNKT cells from MHC-mismatched donors has great potential in protection against GVHD after allogeneic hematopoietic stem cell transplantation.

Direct expansion of human allospecific FoxP3+CD4+ regulatory T cells with allogeneic B cells for therapeutic application

Compelling evidence from animal studies has demonstrated that allospecific FoxP3(+)CD4(+) regulatory T (Treg) cells expanded ex vivo can be used as effective therapeutic tools in the treatment of allograft rejection and graft-vs-host disease. Despite the promising results from animal studies, there remain major barriers to developing Treg cell-based immunotherapy in humans. Currently, no effective approach has been established for selective expansion of human allospecific Treg cells ex vivo. Additionally, the very low frequency of Treg cells present in human peripheral blood could pose a formidable challenge to obtaining a sufficient number of Treg cells from a single donor for ex vivo expansion for therapeutic utilization. Extending our recent finding that mouse B cells preferentially induce expansion of alloreactive Treg cells, we report herein that human Treg cells can be expanded ex vivo with allogeneic B cells. The expanded Treg cells express very high levels of FoxP3, maintain anergic phenotype, and are potent suppressors capable of inhibiting the alloproliferation of third-party responder T cells at very low Treg-to-T effector cell ratio in an alloantigen-specific manner. The alloantigen specificity demonstrated by B cell-expanded Treg cells is not determined by the HLA haplotypes of the Treg cells, but it is induced and determined by the haplotype of the B cells used to expand them. Our findings represent a significant advance in the development of Treg cell-based immunotherapy in humans and raise the possibility of using third-party Treg cells for therapeutic applications.

Mesenchymal stem cells targeting the GVHD

Acute graft-versus-host disease (GVHD) occurs after allogeneic hematopoietic stem cell transplant and is a reaction of donor immune cells against host tissues. About 35%-50% of hematopoietic stem cell transplant (HSCT) recipients will develop acute GVHD. It is associated with considerable morbidity and mortality, particularly in patients who do not respond to primary therapy, which usually consists of glucocorticoids(steroids). Most of the available second-line and third-line treatments for steroid-refractory acute GVHD induce severe immunodeficiency, which is commonly accompanied by lethal infectious complications. Mesenchymal stem cells (MSCs) have been shown to mediate immunomodulatory effects. The recently elucidated immunosuppressive potential of mesenchymal stem cells has set the stage for their clinical testing as cellular immunosuppressants, MSCs have been used in patients with steroid-refractory acute GVHD, and encouraging responses have been obtained in many studies. The utility of MSCs for the treatment of GVHD is becoming clear.

Suppression of xenogeneic graft-versus-host disease by treatment with immunoglobulin-like transcript 3-Fc

Allogeneic hematopoietic cell transplantation represents an important therapy for certain malignant and nonmalignant diseases. However, graft-versus-host disease (GVHD) is a major cause of mortality and morbidity. The search for agents that can efficiently suppress GVHD has been going on for more than half a century. GVHD is particularly strong in xenogeneic donor-recipient combinations, given the unlimited number of potentially immunogenic antigens donor lymphocytes encounter in the host. Using a hu-nonobese diabetic/severe combined immunodeficiency (hu-NOD/SCID) gamma-null model of xenogeneic GVHD, we have demonstrated that treatment with recombinant immunoglobulin-like transcript 3-Fc protein induces the differentiation of CD8(+) T suppressor cells and blocks the cellular and humoral arm of the GVH reaction.

Bone marrow transplantation: new approaches to immunosuppression and management of acute graft-versus-host disease

PURPOSE OF REVIEW

Acute graft-versus-host disease (GVHD) significantly limits the application and the success of allogeneic hematopoietic stem cell transplantation (HSCT). Novel therapies that target the aberrant immune response underlying GVHD are reviewed with particular emphasis on immunomodulatory agents currently incorporated into clinical trials. In addition, regenerative stromal cellular therapy (RSCT) is discussed as an emerging form of novel GVHD therapy.

RECENT FINDINGS

Knowledge for transplant immunology, particularly as it relates to underlying pathophysiology of GVHD, has dramatically increased over the last decade. As a result, new immunomodulatory therapies have been used to treat steroid-refractory GVHD. However, their success has been limited by their lack of clinical experience during HSCT as well as by their associated toxicity profiles. RSCT uniquely offers the potential to enhance donor-derived hematopoiesis and immunity and to ameliorate adverse sequelae associated with GVHD.

SUMMARY

An exciting era incorporating the use of cellular therapeutics during HSCT has arrived. As the experience and understanding for cellular therapies, in general, and RSCT, in particular, increases, so too will their success in benefiting the HSCT recipient beyond limitations of current pharmaceutical agents.