Revisiting graft-versus-host disease models of autoimmunity: new insights in immune regulatory processes

Onconephrology and Thrombotic Microangiopathy: Looking Beyond the Horizon

Thrombotic microangiopathies (TMAs) represent a complex interaction of endothelial and podocyte biology, nephron physiology, complement genetics, and oncologic therapies with host immunology. The complexity of various factors, such as molecular causes, genetic expressions, and immune system mimicking, along with incomplete penetrance, make it difficult to find a straightforward solution. As a result, there may be variations in diagnosis, study, and treatment approaches, and achieving a consensus can be challenging. Here, we review the molecular biology, pharmacology, immunology, molecular genetics, and pathology of the various TMA syndromes in the setting of cancer. Controversies in etiology, nomenclature, and points requiring further clinical, translational, and bench research are discussed. Complement-mediated TMAs, chemotherapy drug-mediated TMAs, TMAs in monoclonal gammopathy, and other TMAs central to onconephrology practice are reviewed in detail. In addition, established and emerging therapies within the US Food and Drug Administration pipeline subsequently are discussed. Finally, a comprehensive review of critical areas of onconephrology clinical practice is presented as practical value to the clinical practitioner and seeds of investigation to be sown among the community of atypical hemolytic uremic syndrome researchers.

Kidney Disease Following Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (SCT) provides a curative option for the treatment of several malignancies. Its growing use is associated with an increased burden of kidney disease. Acute kidney injury is usually seen within the first 100 days of transplantation and has an incidence ranging between 12 and 73%, with the highest rate in myeloablative allogeneic SCT. A large subset of patients after SCT develop chronic kidney disease. They can be broadly classified into thrombotic microangiopathy, nephrotic syndrome, and calcineurin toxicity. Dialysis requirement after SCT is associated with mortality exceeding 80%. Given the higher morbidity and mortality related to development kidney disease, nephrologists need to be aware of the various causes and best treatment options.

A novel monoclonal antibody against human B7-1 protects against chronic graft-vs.-host disease in a murine lupus nephritis model

Lupus nephritis (LN) is the most common complication that causes mortality in patients with systemic lupus erythematosus. The B7-1/B7-2 and CD28/cytotoxic T-lymphocyte associated protein 4 co-stimulatory pathway serves a key role in autoimmune disease and organ transplantation. The aim of the present study was to generate and characterize a monoclonal antibody (mAb; clone 4E5) against human B7-1 and to investigate its potential use for the treatment of LN. The results demonstrated that the 4E5 mAb was successfully generated and able to recognize both human and mouse B7-1. After injection of this mAb into a mouse model with chronic graft-vs.-host disease (cGVHD)-induced lupus-like disease, the expression of CD21, CD23, CD80 and CD86 on B220⁺ B-cells in the spleen, and the concentrations of serum autoantibodies and urine protein, were decreased. Direct immunofluorescence analysis of the kidneys revealed that immunofluorescence of immune complex deposits was weaker in the 4E5-treated mice and electron microscopy analyses of renal tissues indicated that pathological injury of the kidneys of 4E5-treated mice was decreased compared with that in the model control mice. The results of the present study demonstrated that inhibition of the B7-1/CD28 co-stimulatory signaling pathway with the 4E5 mAb may represent a promising strategy to decelerate the progression of LN that is induced by cGVHD with potential for use in the treatment of other autoimmune diseases.

IL-27p28 is essential for parent-to-F1 acute graft-versus-host disease

Acute graft versus host disease (aGVHD) remains a life-threatening complication of bone marrow transplantation. Here we show that IL-27, a member of the IL-12 cytokine family, plays an essential role in a parent-to-F1 murine aGVHD model, using B6 mice as parents and B6D2 mice as F1 recipients. IL-27 is transiently detectable in the serum of B6D2 recipients of B6 spleen cells, with a peak at day 10. Treatment with anti-IL-27p28 mAb MM27.7B1 (αp28Ab), at the time of and six days after B6 cell transfer, blocked GVHD. Protection was associated with host cell survival and undiminished engraftment of donor cells, lack of host B-cell depletion, increased Th2-type immunoglobulin production, a decrease in serum IFN-γ, a drop in anti-H-2D(d) cytotoxic T lymphocyte activity and an increase in Foxp3(+) T cells. We therefore conclude that IL-27 plays a critical role in the parent-to-F1 model of aGVHD and that blocking IL-27 could have therapeutic relevance.

De novo glomerulitis associated with graft-versus-host disease after allogeneic hematopoietic stem cell transplantation: A single-center experience

BACKGROUND

Nephrotic syndrome (NS) and proteinuria are uncommon, often unrecognized manifestations of graft-versus-host disease (GVHD) after hematopoietic stem cell transplantation (HSCT). Only a few isolated case reports and case series involving smaller number of patients who developed NS after HSCT have been published.

METHODS

We reviewed the renal histopathological examination findings and clinical records of 15 patients who developed proteinuria after HSCT at Seoul and Yeouido St. Mary's Hospital (Seoul, Korea). We also measured the anti-PLA2R antibodies (M-type phospholipase A2 receptor) in the serum samples from the seven patients at the time of renal biopsy.

RESULTS

All patients had GVHD. The most common indication for biopsy was proteinuria (>1 g/day), with nine patients having nephrotic range proteinuria. The most common histopathological finding was membranous nephropathy (MN; n = 12). Other findings were membranoproliferative glomerulonephritis, C1q nephropathy, and diabetic nephropathy. Eleven patients were treated with immunosuppressive agents, and three patients were treated only with angiotensin II receptor blocker. The overall response rate, including complete remission (urinary protein level <0.3 g/day) and partial remission (urinary protein level = 0.31-3.4 g/day), was 73%. The mean follow-up period was 26 months, and none of the patients developed end-stage renal disease. All of the seven patients with MN had negative findings for anti-PLA2R antibodies, measured using an enzyme-linked immunosorbent assay kit.

CONCLUSION

In this study the findings of 15 renal biopsies were analyzed and to our knowledge this is the largest clinicopathological study of GVHD-related biopsy-proven nephropathy. Approximately 80% of the patients were MN and 73% responded either partially or completely to immunosuppressive treatment. Currently, there is an increase in the incidence of GVHD-mediated renal disease, and therefore, renal biopsy is essential for diagnosing the nephropathy and preventing the progression of renal disease.

Host CD25+CD4+Foxp3+ regulatory T cells primed by anti-CD137 mAbs inhibit graft-versus-host disease

CD25(+)CD4(+)Foxp3(+) regulatory T cells (Tregs) play a pivotal role in the maintenance of self-tolerance and regulation of immune responses. Previous studies have demonstrated that CD137 signals can promote proliferation and survival of Tregs in vitro. Here, we show that in vivo CD137-induced expansion of Tregs in naive mice was dependent upon IL-2 secreted by memory T cells. Tregs primed by anti-CD137 mAbs had a higher immunosuppressive capacity. Preconditioning with anti-CD137 mAbs significantly inhibited graft-versus-host disease (GVHD) in the C57BL/6 → (C57BL/6 × DBA/2) F1 acute GVHD model. In this disease model, a high proportion of host Tregs remained long-term in the recipient spleen, whereas donor hematopoietic cells replaced other host bone marrow-derived cells. Transient depletion of Tregs before transfer of donor cells completely abrogated the inhibitory effect of anti-CD137 mAbs on GVHD. In addition, adoptive transfer of anti-CD137-primed Tregs ameliorated GVHD. Our results demonstrate that it is possible to enhance the survival and/or the immunosuppressive activity of host Tregs in nonmyeloablative GVHD, and that 1 way of accomplishing this is through the prophylactic use of anti-CD137 mAbs in nonmyeloablative GVHD.

Subclinical GvHD in non-irradiated F1 hybrids: severe lymphoid-tissue GvHD causing prolonged immune dysfunction

GvHD is an important complication of allogeneic hematopoietic SCT. Parent-in-F1 models are frequently used to study GvHD immunobiology; the characteristics of parent-in-F1 GvHD vary between strain combinations and induction protocols. Here, we observed that a high-dose challenge of non-irradiated B6DBA2F1 and B6SJLF1 recipients with C57BL/6 splenocytes left the majority of recipients clinically healthy, while inducing progressive high-grade donor T-cell chimerism. We investigated this previously undescribed pattern of parent-in-F1 T-cell alloreactivity and studied the effect of serial parental splenocyte infusions on epithelial and lymphohematopoietic tissues. The majority of recipients of 4 weekly splenocyte infusions showed long-term survival with gradual establishment of high-grade donor chimerism and without any signs of epithelial-tissue GvHD. A minority of recipients showed BM failure type of GvHD and, respectively, graft rejection. Moreover, long-term F1 chimeras showed protracted pancytopenia, and in peripheral lymphoid tissues severe lymphopenia and near-complete eradication of APCs and dysfunction in antigen-presenting capacity in remaining APC. Hematopoiesis and lymphoid tissue composition recovered only after multilineage donor chimerism had established. In conclusion, we report on a novel type of parent-in-F1 hybrid GvHD, where a cumulative high dose of C57BL/6 parental splenocytes in non-irradiated F1 mice induces subclinical but severe hematolymphoid-tissue GvHD, causing prolonged immuno-incompetence.

Roles of Host Nonhematopoietic Cells in Autoimmunity and Donor Cell Engraftment in Graft-versus-host Disease

Background

Graft-versus-host disease (GVHD) is initiated when alloreactive donor T cells are primed by host APCs to undergo clonal expansion and maturation. Since there is a controversy regarding the role of nonhematopoietic cells in GVHD, we wanted to investigate the influence of MHC disparity on nonhematopoietic cells on the pathogenesis of GVHD in the MHC-haplomismatched C57BL/6 (H-2^b) or DBA/2 (H-2^d)→unirradiated (C57BL/6×DBA/2) F₁(BDF₁; H-2^b/d) murine model of acute GVHD (aGVHD) or chronic GVHD (cGVHD).

Methods

We generated (BDF₁→C57BL/6), (BDF₁→DBA/2), and (BDF₁→BDF₁) chimeras and examined GVHD-related parameters and donor cell engraftment in those chimeras.

Results

Using this experimental system, we found that 1) severe aGVHD across MHC Ag barrier depends on the expression of nonhematopoietically rather than hematopoietically derived alloAgs for maximal GVHD manifestations; 2) host APCs were sufficient to break B cell tolerance to self molecules in cGVHD, whereas host APCs were insufficient to induce autoimmunity in aGVHD; 3) donor cell engraftment was greatly enhanced in the host with MHC-matched nonhematopoietic cells.

Conclusion

Taken together, our results provide an insight into how MHC disparity on GVHD target organs contribute to the pathogenesis of GVHD.

Breaking of CD8+ T cell tolerance through in vivo ligation of CD40 results in inhibition of chronic graft-versus-host disease and complete donor cell engraftment

In the DBA/2 --> unirradiated (C57BL/6 x DBA/2)F(1) model of chronic graft-vs-host disease (cGVHD), donor CD4(+) T cells play a critical role in breaking host B cell tolerance, while donor CD8(+) T cells are rapidly removed and the remaining cells fall into anergy. Previously we have demonstrated that in vivo ligation of GITR (glucocorticoid-induced TNF receptor-related gene) can activate donor CD8(+) T cells, subsequently converting the disease pattern from cGVHD to an acute form. In this study, we investigated the effect of an agonistic mAb against CD40 on cGVHD. Treatment of anti-CD40 mAb inhibited the production of anti-DNA IgG1 autoantibody and the development of glomerulonephritis. The inhibition of cGVHD occurred because anti-CD40 mAb prevented donor CD8(+) T cell anergy such that subsequently activated donor CD8(+) T cells deleted host CD4(+) T cells and host B cells involved in autoantibody production. Additionally, functionally activated donor CD8(+) T cells induced full engraftment of donor hematopoietic cells and exhibited an increased graft-vs-leukemia effect. However, induction of acute GVHD by donor CD8(+) T cells seemed to be not so apparent. Further CTL analysis indicated that there were lower levels of donor CTL activity against host cells in mice that received anti-CD40 mAb, compared with mice that received anti-GITR mAb. Taken together, our results suggest that a different intensity of donor CTL activity is required for removal of host hematopoietic cells, including leukemia vs induction of acute GVHD.

Murine models of chronic graft-versus-host disease: insights and unresolved issues

Chronic graft-versus-host-disease (cGVHD) is a major barrier to successful allogeneic hematopoietic stem cell transplantation (allo-HSCT), with highly variable clinical presentations. The pathophysiology of cGVHD remains relatively poorly understood. The utilization of murine models to study cGVHD encompasses experimental challenges distinct from those that have been successfully used to study acute GVHD (aGVHD). Nevertheless, despite these challenges, murine models of cGVHD have contributed to the understanding of cGVHD, and highlight its mechanistic complexity. In this article, insights into the pathophysiology of cGVHD obtained from murine studies are summarized in the context of their relevancy to clinical cGVHD. Despite experimental limitations, current and future models of murine cGVHD will continue to provide insights into the understanding of clinical cGVHD and provide information for new therapeutic interventions.

Off-label uses of biologics in dermatology: Rituximab, omalizumab, infliximab, etanercept, adalimumab, efalizumab, and alefacept (Part 2 of 2)

Recently, dermatologists have witnessed a revolution in our therapeutic armamentarium with the development of several novel biologic immunomodulators. Although psoriasis remains the only condition in dermatology for which the use of biologic immunomodulators has been approved by the Food and Drug Administration, these drugs have the potential to significantly impact the treatment of several inflammatory conditions in dermatology. This article includes a review of the mechanism of action, dosing, and side-effect profile, as well as a review of the current literature on off-label uses of the CD20-positive B-cell antagonist rituximab, the IgE antagonist omalizumab, the tumor necrosis factor-alpha antagonists infliximab, etanercept, and adalimumab, and the T-cell response modifiers efalizumab and alefacept.

Nephrotic syndrome associated with chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Chronic graft-versus-host disease (cGVHD) is the most common late complication of allogeneic hematopoietic cell transplantation (HCT) causing significant morbidity and mortality. The kidneys are not considered a target organ for cGVHD in humans, although animal models show renal damage. Renal involvement in patients with cGVHD, presenting as nephrotic syndrome (NS), has rarely been reported in patients who received allogeneic transplantation. Herein we describe, by far, the largest series of nine patients with NS associated with cGVHD, including two patients who received a reduced-intensity regimen. Pathological features of membranous nephropathy were the most common finding on renal biopsy. The clinical course of the NS was temporally associated with the classical features of cGVHD in all but one of the nine cases. The clinicopathologic features of NS in our series as well as reports in the literature demonstrate an immunopathologic process typical of antibody-mediated damage consistent with cGVHD. Treatment directed against antibody-mediated damage, such as anti-B-cell antibody may play an important role in ameliorating NS associated with cGVHD.

Conversion of alloantigen-specific CD8+ T cell anergy to CD8+ T cell priming through in vivo ligation of glucocorticoid-induced TNF receptor

In this study, we investigated the effect of an agonistic mAb (DTA-1) against glucocorticoid-induced TNF receptor (GITR) in a murine model of systemic lupus erythematosus-like chronic graft-vs-host disease (cGVHD). A single dose of DTA-1 inhibited the production of anti-DNA IgG1 autoantibody and the development of glomerulonephritis, typical symptoms of cGVHD. DTA-1-treated mice showed clinical and pathological signs of acute GVHD (aGVHD), such as lymphopenia, loss of body weight, increase of donor cell engraftment, and intestinal damage, indicating that DTA-1 shifted cGVHD toward aGVHD. The conversion of cGVHD to aGVHD occurred because DTA-1 prevented donor CD8+ T cell anergy. Functionally active donor CD8+ T cells produced high levels of IFN-gamma and had an elevated CTL activity against host Ags. In in vitro MLR, anergic responder CD8+ T cells were generated, and DTA-1 stimulated the activation of these anergic CD8+ T cells. We further confirmed in vivo that donor CD8+ T cells, but not donor CD4+ T cells, were responsible for the DTA-1-mediated conversion of cGVHD to aGVHD. These results indicate that donor CD8+ T cell anergy is a restriction factor in the development of aGVHD and that in vivo ligation of GITR prevents CD8+ T cell anergy by activating donor CD8+ T cells that otherwise become anergic. In sum, our data suggest GITR as an important costimulatory molecule regulating cGVHD vs aGVHD and as a target for therapeutic intervention in a variety of related diseases.

Stimulation with 4-1BB (CD137) inhibits chronic graft-versus-host disease by inducing activation-induced cell death of donor CD4+ T cells

4-1BB, a member of the tumor necrosis factor (TNF) receptor superfamily, is a costimulator for activated T cells. Previous studies have established that treatment with agonistic anti–4-BB monoclonal antibody (3H3) is effective in reversing the progression of spontaneous systemic lupus erythematosus. Its therapeutic effect is mediated by suppression of autoantibody production. In this report, we show that a single injection of 3H3 blocks chronic graft-versus-host disease (cGVHD) in the parent-into-F1 model. In particular, donor CD4+ T cells are rapidly eliminated from host spleens by activation-induced cell death after 4-1BB triggering. Since donor CD4+ T cells are required for the development of cGVHD, and 3H3-mediated inhibition of autoantibody production occurs without donor CD8+ T cells, 3H3 blocks cGVHD by preventing alloreactive donor CD4+ T cells from activating host B cells. Importantly, 3H3 treatment can reverse the progression of advanced cGVHD. Our findings indicate that agonistic anti–4-1BB monoclonal antibody has potential as an immunotherapeutic agent for preventing and treating cGVHD.

[Auto-immune-like disease post-bone marrow transplantation]

INTRODUCTION

Bone marrow transplantation (BMT) is based on destruction of the patient's bone marrow with rescue of haematopoietic stem cells from a donor. Chronic graft-vs-host disease (GVH) is the major complication post-BMT and mimics some autoimmune diseases, such as scleroderma, sicca syndrome, primary biliary cirrhosis and an increased prevalence of various autoantibodies. Other autoimmune-like manifestations have been reported as case reports or short series. The most common are myasthenia gravis, polymyositis, autoimmune cytopenias and Graves' disease or autoimmune hypothyroidism.

CURRENT KNOWLEDGE AND KEY POINTS

These diseases occur mainly in association with chronic GVH. The pathophysiology of chronic GVH and other autoimmune-like diseases post-BMT remains poorly understood. Different mechanisms have been postulated. Most of the autoimmune events (either chronic GVH or more specific diseases) seem to be related to a poor or inadequate immunologic recovery post-BMT with an imbalance between autoregulatory and autoreactive lymphocytes. Microchimerism and molecular mimicry have been recently evocated. A minority of cases (autoimmune thyroid disorders) is attributed to the direct transfer of autoreactive cells from donor to patient (adoptive immunity).

FUTURE PERSPECTIVES

Despite physiopathologic uncertainty, these autoimmune-like disorders post-BMT are an interesting model for primary autoimmune diseases.

Treatment of chronic graft-versus-host disease with anti-CD20 chimeric monoclonal antibody

We reviewed the clinical outcome of 8 patients with steroid-refractory chronic graft-versus-host disease (GVHD) who received an anti-CD20 chimeric monoclonal antibody (rituximab). Rituximab was given by intravenous infusion at a weekly dose of 375 mg/m(2) for 4 weeks. All patients had received extensive treatment with various immunosuppressive agents; 6 patients had also received extracorporeal photopheresis. All patients had extensive chronic GVHD with diffuse or localized sclerodermoid GVHD and xerophthalmia. Other extracutaneous involvements included cold agglutinin disease with the Raynaud phenomenon, membranous glomerulonephritis, and restrictive or obstructive lung disease. Four patients responded to treatment with ongoing resolution or improvement ranging from 265 to 846 days after therapy, despite recovery of B cells in 3 patients. Rituximab seems to have significant activity in the treatment of refractory chronic GVHD and should be considered for further study in patients with early disease. This study suggests a participating role of B cells in the pathogenesis of chronic GVHD.

Correlation of mixed lymphocyte culture with chronic graft-versus-host disease following allogeneic stem cell transplantation

The purpose of the present study was to evaluate the mixed lymphocyte culture as a predictive assay of acute and chronic graft-versus-host disease (GVHD). We studied 153 patients who received a first bone marrow transplantation from human leukocyte antigen-identical siblings. Acute GVHD was observed in 26 of 128 (20.3%) patients evaluated and chronic GVHD occurred in 60 of 114 (52.6%). One-way mixed lymphocyte culture (MLC) assays were performed by the standard method. MLC results are reported as the relative response (RR) from donor against patient cells. The responses ranged from -47.0 to 40.7%, with a median of 0.5%. The Kaplan-Meier probability of developing GVHD was determined for patients with positive and negative MLC. There was no significant difference in incidence of acute GVHD between the groups studied. However, the incidence of chronic GVHD was higher in recipients with RR >4.5% than in those with RR < or =4.5%. The Cox Proportional Hazards model was used to examine the effect of MLC levels on incidence of chronic GVHD, while adjusting for the potential confounding effect of others suspected or observed risk factors. The relative risk of chronic GVHD was 2.5 for patients with positive MLC (RR >4.5%), 2.9 for those who received peripheral blood progenitor cells as a graft, and 2.2 for patients who developed previous acute GVHD. MLC was not useful for predicting acute GVHD, but MLC with RR >4.5% associated with other risk factors could predict the development of chronic GVHD, being of help for the prevention and/or treatment of this late complication.

The flavonoid Kaempferol suppresses the graft-versus-host reaction by inhibiting type 1 cytokine production and CD8+ T cell engraftment

We have here examined the immunoregulatory effects of a natural flavonoid, Kaempferol, on T cells. Kaempferol suppressed IFN-gamma and IL-2 production but not that of IL-4 by T cells and shifted the Th1/Th2 balance into the Th2 phenotype. In C57BL/6 anti-BDF1 MLC, Kaempferol inhibited the development and expansion of type 1 effector CD8+ T cells and diminished allospecific CTL activity. Based on these in vitro results, we evaluated the effects of Kaempferol treatment on the development of C57BL/6-into-BDF1 acute graft-versus-host disease (GVHD). Brief administration of Kaempferol led to early recovery from body weight loss, increased survival, and reduced tissue injury in the liver and large intestine. Kaempferol treatment activated Th2 cells and the engraftment of donor cells and also diminished GVHD-associated antihost CTL activity. Thus, our study indicates that Kaempferol has the capacity to modulate the Th1/Th2 balance and could be useful for the treatment of cell-mediated immune diseases, such as acute GVHD.

Stem cell transplantation for autoimmune diseases

Much progress has been made in the field of haemopoietic stem cell transplants (HSCTs) for severe autoimmune disorders. Theoretical considerations, animal data and anecdotal evidence suggested some time ago that intensive immunoablation followed by autologous HSCT could restore normal immune reactivity in patients with severe autoimmune disorders. Based on a concept statement issued in 1995, two European societies, the European League Against Rheumatism (EULAR) and the European Group for Blood and Marrow Transplantation (EBMT) began collecting phase I/II trial data in an international collaborative network. Sufficient information from more than 350 patients allows a preliminary assessment with level three evidence. Autologous HSCTs can induce remissions in all disease categories tested so far. Remissions can be transient or durable. HSCTs are associated with significant morbidity and mortality. Treatment-related mortality (TRM) is near 10% at 1 year and is associated with the intensity of the conditioning and the stage of the disease at the time of transplant. Marked interdisease differences exist. There are few data available in haematological autoimmune diseases, more in systemic sclerosis (SSc), systemic lupus erythematosus (SLE), juvenile idiopathic arthritis (JIA) and multiple sclerosis (MS). Patient selection has been recognized as a crucial element from the phase I-II trials. Patients with advanced disease, severely compromised organ function or irreversible organ damage should not be considered as candidates for HSCT. Prospective randomized studies should now determine the value of HSCT compared to standard therapy. Such trials are ongoing for patients with systemic sclerosis (ASTIS trial--Autologous Stem Cell Transplantation International Scleroderma Trial) or are planned for patients with multiple sclerosis (ASTIMS trial--Autologous Stem Cell Transplantation International Multiple Sclerosis Trial) and rheumatoid arthritis (ASTIRA trial--Autologous Stem Cell Transplantation International Rheumatoid Arthritis Trial). More phase II data are needed for other indications such as SLE and JIA.