Islets after kidney transplantation have been shown to positively affect the quality of life of individuals with type 1 diabetes (T1D) by reducing the burden of diabetes complications, but fewer data are available for islet transplantation alone (ITA). The aim of this study was to assess whether ITA has a positive impact on hemostatic and cerebral abnormalities in individuals with T1D.
RESEARCH DESIGN AND METHODS
Prothrombotic factors, platelet function/ultrastructure, and cerebral morphology, metabolism, and function have been investigated over a 15-month follow-up period using ELISA/electron microscopy and magnetic resonance imaging, nuclear magnetic resonance spectroscopy, and neuropsychological evaluation (Profile of Mood States test and paced auditory serial addition test) in 22 individuals with T1D who underwent ITA (n = 12) or remained on the waiting list (n = 10). Patients were homogeneous with regard to metabolic criteria, hemostatic parameters, and cerebral morphology/metabolism/function at the time of enrollment on the waiting list.
At the 15-month follow-up, the group undergoing ITA, but not individuals with T1D who remained on the waiting list, showed 1) improved glucose metabolism; 2) near-normal platelet activation and prothrombotic factor levels; 3) near-normal cerebral metabolism and function; and 4) a near-normal neuropsychological test.
ITA, despite immunosuppressive therapy, is associated with a near-normalization of hemostatic and cerebral abnormalities.
Regulatory T-cells (Tregs) play a pivotal role in the maintenance of immune tolerance and hold great promise as cell therapy for a variety of immune-mediated diseases. However, the cellular mechanisms that regulate Treg maintenance and homeostasis have yet to be fully explored. While Tregs express Granzyme-B (GrB) to suppress effector T-cells via direct-killing, the mechanisms by which they protect themselves from GrB-mediated self-inflicted damage are unknown. We show, for the first time, that both iTregs and nTregs increase their intracellular expression of GrB and its endogenous inhibitor, Serine Protease Inhibitor-6 (Spi6) upon activation. Sub-cellular fractionation and measurement of GrB activity in the cytoplasm of Tregs show that activated Spi6−/− Tregs had significantly higher cytoplasmic GrB activity. We observed an increase in GrB-mediated apoptosis in Spi6−/− nTregs and impaired suppression of alloreactive T-cells in vitro. Spi6−/− Tregs were rescued from apoptosis by the addition of a GrB inhibitor (Z-AAD-CMK) in vitro. Furthermore, adoptive transfer experiments showed that Spi6−/− nTregs were less effective than WT nTregs in suppressing Graft-versus-host-disease (GVHD) due to their impaired survival, as shown in our in vivo bioluminescence imaging. Finally, Spi6-deficient recipients rejected MHC class II-mismatch heart allografts at a much faster rate and showed a higher rate of apoptosis among Tregs, as compared to WT recipients. Our data demonstrate, for the first time, a novel role for Spi6 in Treg homeostasis by protecting activated Tregs from GrB-mediated injury. These data could have significant clinical implications for Treg-based therapy in immune-mediated diseases.
Regulatory T-cells; T cell homeostasis; Tolerance
Abatacept (cytotoxic T-lymphocyte–associated antigen 4–immunoglobulin fusion protein [CTLA-4–Ig]) is a costimulatory inhibitor that targets B7-1 (CD80). The present report describes five patients who had focal segmental glomerulosclerosis (FSGS) (four with recurrent FSGS after transplantation and one with primary FSGS) and proteinuria with B7-1 immunostaining of podocytes in kidney-biopsy specimens. Abatacept induced partial or complete remissions of proteinuria in these patients, suggesting that B7-1 may be a useful biomarker for the treatment of some glomerulopathies. Our data indicate that abatacept may stabilize β1-integrin activation in podocytes and reduce proteinuria in patients with B7-1–positive glomerular disease.
The lymphocytic ionotropic purinergic P2X receptors (P2X1R-P2X7R, or P2XRs) sense ATP released during cell damage-activation, thus regulating T-cell activation. We aim to define the role of P2XRs during islet allograft rejection and to establish a novel anti-P2XRs strategy to achieve long-term islet allograft function. Our data demonstrate that P2X1R and P2X7R are induced in islet allograft-infiltrating cells, that only P2X7R is increasingly expressed during alloimmune response, and that P2X1R is augmented in both allogeneic and syngeneic transplantation. In vivo short-term P2X7R targeting (using periodate-oxidized ATP [oATP]) delays islet allograft rejection, reduces the frequency of Th1/Th17 cells, and induces hyporesponsiveness toward donor antigens. oATP-treated mice displayed preserved islet grafts with reduced Th1 transcripts. P2X7R targeting and rapamycin synergized in inducing long-term islet function in 80% of transplanted mice and resulted in reshaping of the recipient immune system. In vitro P2X7R targeting using oATP reduced T-cell activation and diminished Th1/Th17 cytokine production. Peripheral blood mononuclear cells obtained from long-term islet-transplanted patients showed an increased percentage of P2X7R+CD4+ T cells compared with controls. The beneficial effects of oATP treatment revealed a role for the purinergic system in islet allograft rejection, and the targeting of P2X7R is a novel strategy to induce long-term islet allograft function.
Ischemia/reperfusion (I/R) is one of the most common causes of acute kidney injury. Reactive oxygen species have been recognized to be an important contributor to the pathogenesis of I/R injury. We hypothesize that a non-peptidyl low molecular weight radical scavenger (IAC) therapy may counteract this factor, ultimately providing some protection after acute phase renal I/R injury. The aim of this preliminary study was to assess the ability of IAC to reduce acute kidney injury in C57BL/6 mice after 30-minute of bilateral ischemia followed by reperfusion. The rise in serum creatinine level was higher in C57BL/6 control mice after I/R when compared to IAC (1 mg)-treated mice. Control mice showed greater body weight loss compared to IAC-treated mice, and at pathology, reduced signs of tubular necrosis were also evident in IAC-treated mice. These preliminary evidences lay the basis for more comprehensive studies on the positive effects of IAC as a complementary therapeutic approach for acute phase renal I/R injury.
Ischemia/reperfusion; Kidney disease; Kidney transplantation; Radical oxygen species; Inflammation
Heart transplantation is a lifesaving procedure for patients with end-stage heart failure. Despite much effort and advances in the field, current immunosuppressive regimens are still associated with poor long-term cardiac allograft outcomes as well as with the development of complications including infections and malignancies. The development of a novel, short-term and effective immunomodulatory protocol will thus be an important achievement. The purine adenosine 5′-triphosphate (ATP), released during cell damage/activation, is sensed by the ionotropic purinergic receptor P2X7 (P2X7R) on lymphocytes and regulates T cell activation. Novel clinical-grade P2X7R inhibitors are available, rendering the targeting of P2X7R a potential therapy in cardiac transplantation.
Methods and Results
We analyzed P2X7R expression in patients and mice and P2X7R targeting in murine recipients in the context of cardiac transplantation. Our data demonstrate that P2X7R is specifically upregulated in graft-infiltrating lymphocytes in cardiac-transplanted humans and mice. Short-term P2X7R targeting with periodate-oxidized ATP (oATP) promotes long-term cardiac transplant survival in 80% of murine recipients of a fully mismatched allograft. Long-term survival of cardiac transplants was associated with reduced T cell activation, Th1/Th17 differentiation and inhibition of STAT3 phosphorylation in T cells, thus leading to a reduced transplant infiltrate and coronaropathy. In vitro genetic upregulation of the P2X7R pathway was also shown to stimulate Th1/Th17 cell generation. Finally, P2X7R targeting halted the progression of coronaropathy in a murine model of chronic rejection as well.
P2X7R targeting is a novel clinically relevant strategy to prolong cardiac transplant survival.
Transplantation; rejection; P2X7R; immunology
A short course of anti-CD45RB leads to long-term islet allograft survival and donor-specific tolerance in approximately half of immunocompetent mice. We have previously demonstrated that anti-CD45RB antibody-mediated tolerance requires B cells for cardiac allograft survival. We therefore asked whether B cells were also required for anti-CD45RB antibody-mediated survival of islets. Unexpectedly, we found that nearly 100% of islet allografts survive long-term in B cell-deficient mice. Similarly, B cell depletion by anti-CD22/cal augmented anti-CD45RB mediated tolerance when administered pre-transplant, although it had no effect on tolerance induction when administered post-transplant. Our results demonstrate that the role of B cells in promoting tolerance with anti-CD45RB is graft-specific, promoting tolerance in cardiac grafts but resisting tolerance in islet transplantation. These findings may help elucidate the varied action of B cells in promoting tolerance versus rejection.
B cell; anti-CD45RB; anti-CD22; islet transplantation; tolerance
Human clinical trials in type 1 diabetes (T1D) patients using mesenchymal stem cells (MSC) are presently underway without prior validation in a mouse model for the disease. In response to this void, we characterized bone marrow-derived murine MSC for their ability to modulate immune responses in the context of T1D, as represented in NOD mice. In comparison to NOD mice, BALB/ c-MSC mice were found to express higher levels of the negative costimulatory molecule PD-L1 and to promote a shift toward Th2-like responses in treated NOD mice. In addition, transfer of MSC from resistant strains (i.e., nonobese resistant mice or BALB/c), but not from NOD mice, delayed the onset of diabetes when administered to prediabetic NOD mice. The number of BALB/c-MSC trafficking to the pancreatic lymph nodes of NOD mice was higher than in NOD mice provided autologous NOD-MSC. Administration of BALB/c-MSC temporarily resulted in reversal of hyperglycemia in 90% of NOD mice (p = 0.002). Transfer of autologous NOD-MSC imparted no such therapeutic benefit. We also noted soft tissue and visceral tumors in NOD-MSC-treated mice, which were uniquely observed in this setting (i.e., no tumors were present with BALB/c- or nonobese resistant mice-MSC transfer). The importance of this observation remains to be explored in humans, as inbred mice such as NOD may be more susceptible to tumor formation. These data provide important preclinical data supporting the basis for further development of allogeneic MSC-based therapies for T1D and, potentially, for other autoimmune disorders.
Mounting evidence from human, animal, and in vitro studies indicates that existing drugs, developed to treat other disorders, might also be effective in preventing or slowing the progression of diabetic nephropathy to end stage renal disease. Examples of such drugs include the urate-lowering agent allopurinol, the anti-TNF agents etanercept and infliximab, and the immuno-modulating drug abatacept. Since some these medications are already on the market and have been used for a number of years for other indications, they can be immediately tested in humans for a beneficial effect on renal function in diabetes. Special emphasis should be placed on evaluating the use of these drugs early in the course of diabetic nephropathy when renal damage is most likely to be reversible and interventions can yield the greatest delay to end stage renal disease.
diabetic nephropathy; uric acid; inflammation; immune system; novel therapeutics
Type 1 diabetes (T1D) remains a major health problem worldwide, with a steadily rising incidence yet no cure. Phosphoinositide 3-kinase-γ (PI3Kγ), a member of a family of lipid kinases expressed primarily in leukocytes, has been the subject of substantial research for its role in inflammatory diseases. However, the role of PI3Kγ inhibition in suppressing autoimmune T1D remains to be explored. We tested the role of the PI3Kγ inhibitor AS605240 in preventing and reversing diabetes in NOD mice and assessed the mechanisms by which this inhibition abrogates T1D. Our data indicate that the PI3Kγ pathway is highly activated in T1D. In NOD mice, we found upregulated expression of phosphorylated Akt (PAkt) in splenocytes. Notably, T regulatory cells (Tregs) showed significantly lower expression of PAkt compared with effector T cells. Inhibition of the PI3Kγ pathway by AS605240 efficiently suppressed effector T cells and induced Treg expansion through the cAMP response element-binding pathway. AS605240 effectively prevented and reversed autoimmune diabetes in NOD mice and suppressed T-cell activation and the production of inflammatory cytokines by autoreactive T cells in vitro and in vivo. These studies demonstrate the key role of the PI3Kγ pathway in determining the balance of Tregs and autoreactive cells regulating autoimmune diabetes.
CD160 is a cell surface molecule expressed by most NK cells and approximately 50% of CD8+ cytotoxic T lymphocytes. Engagement of CD160 by MHC class-I directly triggers a costimulatory signal to TCR-induced proliferation, cytokine production and cytotoxic effector functions. The role of CD160 in alloimmunity is unknown. Using a newly generated CD160 fusion protein (CD160Ig) we examined the role of the novel costimulatory molecule CD160 in mediating CD4+ or CD8+ T cell driven allograft rejection. CD160Ig inhibits alloreactive CD8+ T cell proliferation and IFN-γ production in vitro, in particular in the absence of CD28 costimulation. Consequently CD160Ig prolongs fully mismatched cardiac allograft survival in CD4−/−, CD28−/− knockout and CTLA4Ig treated WT recipients, but not in WT or CD8−/− knockout recipients. The prolonged cardiac allograft survival is associated with reduced alloreactive CD8+ T cell proliferation, effector/memory responses and alloreactive IFN-γ production. Thus, CD160 signaling is particularly important in CD28-independent effector/memory CD8+ alloreactive T cell activation in vivo and therefore may serve as a novel target for prevention of allograft rejection.
The pathogenesis of brain disorders in type 1 diabetes (T1D) is multifactorial and involves the adverse effects of chronic hyperglycemia and of recurrent hypoglycemia. Kidney-pancreas (KP), but not kidney alone (KD), transplantation is associated with sustained normoglycemia, improvement in quality of life, and reduction of morbidity/mortality in diabetic patients with end-stage renal disease (ESRD).
RESEARCH DESIGN AND METHODS
The aim of our study was to evaluate with magnetic resonance imaging and nuclear magnetic resonance spectroscopy (1H MRS) the cerebral morphology and metabolism of 15 ESRD plus T1D patients, 23 patients with ESRD plus T1D after KD (n = 9) and KP (n = 14) transplantation, and 8 age-matched control subjects.
Magnetic resonance imaging showed a higher prevalence of cerebrovascular disease in ESRD plus T1D patients (53% [95% CI 36–69]) compared with healthy subjects (25% [3–6], P = 0.04). Brain 1H MRS showed lower levels of N-acetyl aspartate (NAA)-to-choline ratio in ESRD plus T1D, KD, and KP patients compared with control subjects (control subjects vs. all, P < 0.05) and of NAA-to-creatine ratio in ESRD plus T1D compared with KP and control subjects (ESRD plus T1D vs. control and KP subjects, P ≤ 0.01). The evaluation of the most common scores of psychological and neuropsychological function showed a generally better intellectual profile in control and KP subjects compared with ESRD plus T1D and KD patients.
Diabetes and ESRD are associated with a precocious form of brain impairment, chronic cerebrovascular disease, and cognitive decline. In KP-transplanted patients, most of these features appeared to be near normalized after a 5-year follow-up period of sustained normoglycemia.
Despite significant nephrotoxicity, calcineurin inhibitors (CNIs) remain the cornerstone of immunosuppression in solid organ transplantation. We, along with others, have reported tolerogenic properties of anti-thymocyte globulin (ATG, Thymoglobulin®), evinced by its ability both to spare Tregs from depletion in vivo and, when administered at low, non-depleting doses, to expand Tregs ex vivo. Clinical trials investigating B7/CD28 blockade (LEA29Y, Belatacept) in kidney transplant recipients have proven that the replacement of toxic CNI use is feasible in selected populations.
Rabbit polyclonal anti-murine thymocyte globulin (mATG) was administered as induction and/or prolonged, low-dose therapy, in combination with CTLA4-Ig, in a stringent, fully MHC-mismatched murine skin transplant model to assess graft survival and mechanisms of action.
Prolonged, low-dose mATG, combined with CTLA4-Ig, effectively promotes engraftment in a stringent transplant model. Our data demonstrate that mATG achieves graft acceptance primarily by promoting Tregs, while CTLA4-Ig enhances mATG function by limiting activation of the effector T cell pool in the early stages of treatment, and by inhibiting production of anti-rabbit antibodies in the maintenance phase, thereby promoting regulation of alloreactivity.
These data provide the rationale for development of novel, CNI-free clinical protocols in human transplant recipients.
B cells participate in the priming of the allo- and autoimmune responses, and their depletion can thus be advantageous for islet transplantation. Herein, we provide an extensive study of the effect of B-cell depletion in murine models of islet transplantation. Islet transplantation was performed in hyperglycemic B-cell–deficient(μMT) mice, in a purely alloimmune setting (BALB/c into hyperglycemic C57BL/6), in a purely autoimmune setting (NOD.SCID into hyperglycemic NOD), and in a mixed allo-/autoimmune setting (BALB/c into hyperglycemic NOD). Inotuzumab ozogamicin murine analog (anti-CD22 monoclonal antibody conjugated with calicheamicin [anti-CD22/cal]) efficiently depleted B cells in all three models of islet transplantation examined. Islet graft survival was significantly prolonged in B-cell–depleted mice compared with control groups in transplants of islets from BALB/c into C57BL/6 (mean survival time [MST]: 16.5 vs. 12.0 days; P = 0.004), from NOD.SCID into NOD (MST: 23.5 vs. 14.0 days; P = 0.03), and from BALB/c into NOD (MST: 12.0 vs. 5.5 days; P = 0.003). In the BALB/c into B-cell–deficient mice model, islet survival was prolonged as well (MST: μMT = 32.5 vs. WT = 14 days; P = 0.002). Pathology revealed reduced CD3+ cell islet infiltration and confirmed the absence of B cells in treated mice. Mechanistically, effector T cells were reduced in number, concomitant with a peripheral Th2 profile skewing and ex vivo recipient hyporesponsiveness toward donor-derived antigen as well as islet autoantigens. Finally, an anti-CD22/cal and CTLA4-Ig–based combination therapy displayed remarkable prolongation of graft survival in the stringent model of islet transplantation (BALB/c into NOD). Anti-CD22/cal–mediated B-cell depletion promotes the reduction of the anti-islet immune response in various models of islet transplantation.
Interleukin-21 (IL-21) is a proinflammatory cytokine that has been shown to affect Treg/Teff balance. However, the mechanism by which IL-21 orchestrates alloimmune response and interplays with Tregs is still unclear.
RESEARCH DESIGN AND METHODS
The interplay between IL-21/IL-21R signaling, FoxP3 expression, and Treg survival and function was evaluated in vitro in immunologically relevant assays and in vivo in allogenic and autoimmune models of islet transplantation.
IL-21R expression decreases on T cells and B cells in vitro and increases in the graft in vivo, while IL-21 levels increase in vitro and in vivo during anti-CD3/anti-CD28 stimulation/allostimulation in the late phase of the alloimmune response. In vitro, IL-21/IL-21R signaling (by using rmIL-21 or genetically modified CD4+ T cells [IL-21 pOrf plasmid–treated or hIL-21-Tg mice]) enhances the T-cell response during anti-CD3/anti-CD28 stimulation/allostimulation, prevents Treg generation, inhibits Treg function, induces Treg apoptosis, and reduces FoxP3 and FoxP3-dependent gene transcripts without affecting FoxP3 methylation status. In vivo targeting of IL-21/IL-21R expands intragraft and peripheral Tregs, promotes Treg neogenesis, and regulates the antidonor immune response, whereas IL-21/IL-21R signaling in Doxa-inducible ROSA-rtTA-IL-21-Tg mice expands Teffs and FoxP3− cells. Treatment with a combination of mIL-21R.Fc and CTLA4-Ig (an inhibitor of the early alloimmune response) leads to robust graft tolerance in a purely alloimmune setting and prolonged islet graft survival in NOD mice.
IL-21 interferes with different checkpoints of the FoxP3 Treg chain in the late phase of alloimmune response and, thus, acts as an antitolerogenic cytokine. Blockade of the IL-21/IL-21R pathway could be a precondition for tolerogenic protocols in transplantation.
Antagonism of CXCR4 disrupts the interaction between the CXCR4 receptor on HSCs and the CXCL12 expressed by stromal cells in the bone marrow, which subsequently results in the shedding of hematopoietic stem cells (HSCs) to the periphery. Due to their profound immunomodulatory effects, HSCs have emerged as a promising therapeutic strategy for autoimmune disorders. We sought to investigate the immunomodulatory role of mobilized autologous HSCs, via target of the CXCR4-CXL12 axis, to promote engraftment of islet cell transplantation. Islets from BALB/c mice were transplanted beneath the kidney capsule of hyperglycemic C57BL/6 mice, and treatment of recipients with CXCR4 antagonist resulted in mobilization of HSCs and in prolongation of islet graft survival. Addition of Rapamycin to anti-CXCR4 therapy further promoted HSC mobilization and islet allograft survival, inducing a robust and transferable host hyporesponsiveness, while administration of an ACK2 (anti-CD117) mAb halted CXCR4 antagonist-mediated HSC release and restored allograft rejection. Mobilized HSCs were shown to express high levels of the negative co-stimulatory molecule PD-L1, and HSCs extracted from WT mice, but not from PD-L1 KO, suppressed the in vitro alloimmune response. Moreover, HSC mobilization in PD-L1 KO mice failed to prolong islet allograft survival. Targeting the CXCR4-CXCL12 axis thus mobilizes autologous HSCs and promotes long-term survival of islet allografts via a PD-L1-mediated mechanism.
Diabetes; CXCR4-CXCL12 axis; islet transplantation; stem cells
Hyperglycaemia occurring in diabetes is responsible for accelerated arterial remodeling and atherosclerosis, affecting the macro- and the microcirculatory system. Vessel injury is mainly related to deregulation of glucose homeostasis and insulin/insulin-precursors production, generation of advanced glycation end-products, reduction in nitric oxide synthesis, and oxidative and reductive stress. It occurs both at extracellular level with increased calcium and matrix proteins deposition and at intracellular level, with abnormalities of intracellular pathways and increased cell death. Peripheral arterial disease, coronary heart disease, and ischemic stroke are the main causes of morbidity/mortality in diabetic patients representing a major clinical and economic issue. Pharmacological therapies, administration of growth factors, and stem cellular strategies are the most effective approaches and will be discussed in depth in this comprehensive review covering the regenerative therapies of diabetic microangiopathy.
Bone-marrow-derived cells-mediated postnatal vasculogenesis has been reported as the main responsible for the regulation of vascular homeostasis in adults. Since their discovery, endothelial progenitor cells have been depicted as mediators of postnatal vasculogenesis for their peculiar phenotype (partially staminal and partially endothelial), their ability to differentiate in endothelial cell line and to be incorporated into the vessels wall during ischemia/damage. Diabetes mellitus, a condition characterized by cardiovascular disease, nephropathy, and micro- and macroangiopathy, showed a dysfunction of endothelial progenitor cells. Herein, we review the mechanisms involved in diabetes-related dysfunction of endothelial progenitor cells, highlighting how hyperglycemia affects the different steps of endothelial progenitor cells lifetime (i.e., bone marrow mobilization, trafficking into the bloodstream, differentiation in endothelial cells, and homing in damaged tissues/organs). Finally, we review preclinical and clinical strategies that aim to revert diabetes-induced dysfunction of endothelial progenitor cells as a means of finding new strategies to prevent diabetic complications.
A number of clinical trials are underway to test whether mesenchymal stem cells (MSCs) are effective in treating various diseases, including type 1 diabetes. Although this cell therapy holds great promise, the optimal source of MSCs has yet to be determined with respect to major histocompatibility complex matching. Here, we examine this question by testing the ability of congenic MSCs, obtained from the NOR mouse strain, to reverse recent-onset type 1 diabetes in NOD mice, as well as determine the immunomodulatory effects of NOR MSCs in vivo.
RESEARCH DESIGN AND METHODS
NOR MSCs were evaluated with regard to their in vitro immunomodulatory function in the context of autoreactive T-cell proliferation and dendritic cell (DC) generation. The in vivo effect of NOR MSC therapy on reversal of recent-onset hyperglycemia and on immunogenic cell subsets in NOD mice was also examined.
NOR MSCs were shown to suppress diabetogenic T-cell proliferation via PD-L1 and to suppress generation of myeloid/inflammatory DCs predominantly through an IL-6-dependent mechanism. NOR MSC treatment of experimental type 1 diabetes resulted in long-term reversal of hyperglycemia, and therapy was shown to alter diabetogenic cytokine profile, to diminish T-cell effector frequency in the pancreatic lymph nodes, to alter antigen-presenting cell frequencies, and to augment the frequency of the plasmacytoid subset of DCs.
These studies demonstrate the inimitable benefit of congenic MSC therapy in reversing experimental type 1 diabetes. These data should benefit future clinical trials using MSCs as treatment for type 1 diabetes.
To investigate a new clinically relevant immunoregulatory strategy based on treatment with murine Thymoglobulin mATG Genzyme and CTLA4-Ig in NOD mice to prevent allo- and autoimmune activation using a stringent model of islet transplantation and diabetes reversal.
RESEARCH DESIGN AND METHODS
Using allogeneic islet transplantation models as well as NOD mice with recent onset type 1 diabetes, we addressed the therapeutic efficacy and immunomodulatory mechanisms associated with a new immunoregulatory protocol based on prolonged low-dose mATG plus CTLA4-Ig.
BALB/c islets transplanted into hyperglycemic NOD mice under prolonged mATG+CTLA4-Ig treatment showed a pronounced delay in allograft rejection compared with untreated mice (mean survival time: 54 vs. 8 days, P < 0.0001). Immunologic analysis of mice receiving transplants revealed a complete abrogation of autoimmune responses and severe downregulation of alloimmunity in response to treatment. The striking effect on autoimmunity was confirmed by 100% diabetes reversal in newly hyperglycemic NOD mice and 100% indefinite survival of syngeneic islet transplantation (NOD.SCID into NOD mice).
The capacity to regulate alloimmunity and to abrogate the autoimmune response in NOD mice in different settings confirmed that prolonged mATG+CTLA4-Ig treatment is a clinically relevant strategy to translate to humans with type 1 diabetes.
In type 1 diabetes (T1D) vascular complications such as accelerated atherosclerosis and diffused macro-/microangiopathy are linked to chronic hyperglycemia with a mechanism that is not yet well understood. End-stage renal disease (ESRD) worsens most diabetic complications, particularly, the risk of morbidity and mortality from cardiovascular disease is increased several fold.
Methods and Findings
We evaluated protein regulation and expression in skin biopsies obtained from T1D patients with and without ESRD, to identify pathways of persistent cellular changes linked to diabetic vascular disease. We therefore examined pathways that may be normalized by restoration of normoglycemia with kidney-pancreas (KP) transplantation. Using proteomic and ultrastructural approaches, multiple alterations in the expression of proteins involved in oxidative stress (catalase, superoxide dismutase 1, Hsp27, Hsp60, ATP synthase δ chain, and flavin reductase), aerobic and anaerobic glycolysis (ACBP, pyruvate kinase muscle isozyme, and phosphoglycerate kinase 1), and intracellular signaling (stratifin-14-3-3, S100-calcyclin, cathepsin, and PPI rotamase) as well as endothelial vascular abnormalities were identified in T1D and T1D+ESRD patients. These abnormalities were reversed after KP transplant. Increased plasma levels of malondialdehyde were observed in T1D and T1D+ESRD patients, confirming increased oxidative stress which was normalized after KP transplant.
Our data suggests persistent cellular changes of anti-oxidative machinery and of aerobic/anaerobic glycolysis are present in T1D and T1D+ESRD patients, and these abnormalities may play a key role in the pathogenesis of hyperglycemia-related vascular complications. Restoration of normoglycemia and removal of uremia with KP transplant can correct these abnormalities. Some of these identified pathways may become potential therapeutic targets for a new generation of drugs.
OBJECTIVES—To investigate a B-cell–depleting strategy to reverse diabetes in naïve NOD mice.
RESEARCH DESIGN AND METHODS—We targeted the CD22 receptor on B-cells of naïve NOD mice to deplete and reprogram B-cells to effectively reverse autoimmune diabetes.
RESULTS—Anti-CD22/cal monoclonal antibody (mAb) therapy resulted in early and prolonged B-cell depletion and delayed disease in pre-diabetic mice. Importantly, when new-onset hyperglycemic mice were treated with the anti-CD22/cal mAb, 100% of B-cell–depleted mice became normoglycemic by 2 days, and 70% of them maintained a state of long-term normoglycemia. Early therapy after onset of hyperglycemia and complete B-cell depletion are essential for optimal efficacy. Treated mice showed an increase in percentage of regulatory T-cells in islets and pancreatic lymph nodes and a diminished immune response to islet peptides in vitro. Transcriptome analysis of reemerging B-cells showed significant changes of a set of proinflammatory genes. Functionally, reemerging B-cells failed to present autoantigen and prevented diabetes when cotransferred with autoreactive CD4+ T-cells into NOD.SCID hosts.
CONCLUSIONS—Targeting CD22 depletes and reprograms B-cells and reverses autoimmune diabetes, thereby providing a blueprint for development of novel therapies to cure autoimmune diabetes.