Lipid raft facilitated ligation of K-alpha1-tubulin by specific antibodies on epithelial cells: Role in pathogenesis of chronic rejection following human lung transplantation

Vascular restenosis in coronary artery bypass grafting might be associated with VEGF-C/VEGFR-3 signaling pathway

The vascular endothelial growth factor (VEGF) family of peptides and caveolins (CAVs) are reported to contribute, in early graft failure in patients, a coronary artery bypass grafting (CABG). To investigate the possible association of ultimate luminal occlusion to VEGFs and CAVs expression, a functional analysis (based on the molecular biology, bioinformatics, histology, and clinical studies) was performed. Twenty-four hundred and sixty-eight CABG patients diagnosed with multivessel stable coronary artery disease (CAD) were enrolled into prospective study and assigned to two subgroups: double- and triple-vessel CAD subjects. Distal parts of all the harvested saphenous vein (SV) and internal thoracic artery (ITA) segments were used for further tests. ITA graft failure did not differ between double-vessel and triple-vessel CAD patients. The number of SV occlusions was significantly higher in triple-vessel CAD subjects. The microarray analysis performed on SV and ITA samples obtained exclusively from triple-vessel CAD patients who developed early graft occlusion revealed 383 genes with increased and 301 genes with decreased expression in ITA samples as compared to SV grafts. This was followed by functional analysis of ‘blood vessel development’ group of genes. Average VEGF-C expression in ITA grafts was higher than in corresponding SV grafts; FLT4 expression was significantly higher in SV than in ITA transplants. VEGFR-3 and CAV3 expression demonstrated immunohistochemically in SMCs of the tunica media of SV grafts predicted their early restenosis in triple-vessel CAD patients. CAV2 protein expression in SMCs of ITA grafts indicated the risk of early graft failure both in double-vessel and triple-vessel CAD subjects.

Th17 Responses to Collagen Type V, kα1-Tubulin, and Vimentin Are Present Early in Human Development and Persist Throughout Life

T helper 17 (Th17)-dependent autoimmune responses can develop after heart or lung transplantation and are associated with fibro-obliterative forms of chronic rejection; however, the specific self-antigens involved are typically different from those associated with autoimmune disease. To investigate the basis of these responses, we investigated whether removal of regulatory T cells or blockade of function reveals a similar autoantigen bias. We found that Th17 cells specific for collagen type V (Col V), kα1-tubulin, and vimentin were present in healthy adult peripheral blood mononuclear cells, cord blood, and fetal thymus. Using synthetic peptides and recombinant fragments of the Col V triple helical region (α1[V]), we compared Th17 cells from healthy donors with Th17 cells from Col V-reactive heart and lung patients. Although the latter responded well to α1(V) fragments and peptides in an HLA-DR-restricted fashion, Th17 cells from healthy persons responded in an HLA-DR-restricted fashion to fragments but not to peptides. Col V, kα1-tubulin, and vimentin are preferred targets of a highly conserved, hitherto unknown, preexisting Th17 response that is MHC class II restricted. These data suggest that autoimmunity after heart and lung transplantation may result from dysregulation of an intrinsic mechanism controlling airway and vascular homeostasis.

Immune Responses to Tissue-Restricted Nonmajor Histocompatibility Complex Antigens in Allograft Rejection

Chronic diseases that result in end-stage organ damage cause inflammation, which can reveal sequestered self-antigens (SAgs) in that organ and trigger autoimmunity. The thymus gland deletes self-reactive T-cells against ubiquitously expressed SAgs, while regulatory mechanisms in the periphery control immune responses to tissue-restricted SAgs. It is now established that T-cells reactive to SAgs present in certain organs (e.g., lungs, pancreas, and intestine) are incompletely eliminated, and the dysregulation of peripheral immuneregulation can generate immune responses to SAgs. Therefore, chronic diseases can activate self-reactive lymphocytes, inducing tissue-restricted autoimmunity. During organ transplantation, donor lymphocytes are tested against recipient serum (i.e., cross-matching) to detect antibodies (Abs) against donor human leukocyte antigens, which has been shown to reduce Ab-mediated hyperacute rejection. However, primary allograft dysfunction and rejection still occur frequently. Because donor lymphocytes do not express tissue-restricted SAgs, preexisting Abs against SAgs are undetectable during conventional cross-matching. Preexisting and de novo immune responses to tissue-restricted SAgs (i.e., autoimmunity) play a major role in rejection. In this review, we discuss the evidence that supports autoimmunity as a contributor to rejection. Testing for preexisting and de novo immune responses to tissue-restricted SAgs and treatment based on immune responses after organ transplantation may improve short- and long-term outcomes after transplantation.

Cardiac antibody production to self-antigens in children and adolescents during and following the correction of severe diabetic ketoacidosis

Diabetic cardiomyopathy (DC) is an independent phenotype of diabetic cardiovascular disease. The understanding of the pathogenesis of DC in young patients with type 1 diabetes (T1D) is limited. The cardiac insults of diabetic ketoacidosis (DKA) and progression of DC could include development of antibodies (Abs) to cardiac self-antigens (SAgs) such as: myosin (M), vimentin (V) and k-alpha 1 tubulin (Kα1T). The goal of this study is to determine if the insults of severe DKA and its inflammatory cascade are associated with immune responses to SAgs. Development of Abs to the SAgs were determined by an ELISA using sera collected at three time points in relation to severe DKA (pH < 7.2). Results demonstrate significant differences between the development of Abs to VIM and a previously reported diastolic abnormality (DA) during DKA and its treatment and a NDA group at 2-3 months post DKA (p = 0.0452). A significant association is present between T1D duration (<3 years) and Abs to Kα1T (p = 0.0134). Further, Abs to MYO and VIM are associated with inflammatory cytokines. We propose that severe DKA initiates the synthesis of Abs to cardiac SAgs that are involved in the early immunopathogenesis of DC in young patients with T1D.

Sodium channel γENaC mediates IL-17 synergized high salt induced inflammatory stress in breast cancer cells

Chronic inflammation is known to play a critical role in the development of cancer. Recent evidence suggests that high salt in the tissue microenvironment induces chronic inflammatory milieu. In this report, using three breast cancer-related cell lines, we determined the molecular basis of the potential synergistic inflammatory effect of sodium chloride (NaCl) with interleukin-17 (IL-17). Combined treatment of high NaCl (0.15M) with sub-effective IL-17 (0.1 nM) induced enhanced growth in breast cancer cells along with activation of reactive nitrogen and oxygen (RNS/ROS) species known to promote cancer. Similar effect was not observed with equi-molar mannitol. This enhanced of ROS/RNS activity correlates with upregulation of γENaC an inflammatory sodium channel. The similar culture conditions have also induced expression of pro-inflammatory cytokines such as IL-6, TNFα etc. Taken together, these data suggest that high NaCl in the cellular microenvironment induces a γENaC mediated chronic inflammatory response with a potential pro-carcinogenic effect.

Autoimmune Reactivity in Graft Injury: Player or Bystander?

Organ transplantation is the only viable treatment for several end-stage organ failures. However chronic rejection prevents long-term graft survival. Traditionally this rejection was attributed to the development of alloimmunity in transplant patients. However recent evidence suggests that autoimmunity plays a larger role in chronic rejection of certain organ transplants, than alloimmunity. In this review we will focus on the history of autoimmunity in solid-organ transplantation and at look the Collagen Type V, K-α-tubulin, Vimentin, Cardiac myosin and Heat Shock Proteins as classical examples of auto-antigens in organ transplantation. We will also look at some of the recent reports looking at the mechanisms of autoimmunity and try to provide answers to some of the age-old questions in autoimmunity.

3-[(dodecylthiocarbonyl)methyl]-glutarimide attenuates graft arterial disease by suppressing alloimmune responses and vascular smooth muscle cell proliferation

BACKGROUND

Graft arterial disease (GAD) is a major cause of late graft loss after organ transplantation. Alloimmune responses and vascular remodeling eventually cause the transplant organ to develop GAD. In this study, we aimed to limit the development of GAD by inhibiting alloimmune responses and vascular smooth muscle cell (VSMC) proliferation with a new compound, 3-[(dodecylthiocarbonyl)methyl]-glutarimide ([DTCM]-glutarimide), in a murine cardiac model of GAD.

METHODS

The hearts from B6.CH-2 mice were transplanted into C57BL/6 mouse recipients to examine the extent of GAD. The recipients were treated with either vehicle or DTCM-glutarimide intraperitoneally (40 mg/kg per day) for 4 weeks.

RESULTS

The administration of DTCM-glutarimide attenuated GAD formation (luminal occlusion: 37.9 ± 5.9% vs 14.8 ± 5.4%, P < 0.05) by inhibiting the number of graft-infiltrating cells and decreasing alloreactive interferon (IFN)-γ production compared with control mice, as measured by the Enzyme-linked ImmunoSpot assay. In vitro, VSMCs proliferated on stimulation with either basic fibroblast growth factor or IFN-γ and splenocytes after transplantation, but the addition of DTCM-glutarimide resulted in the inhibition of VSMC proliferation. Moreover, DTCM-glutarimide suppressed cyclin D1 expression and inhibited cell cycle progression from G1 to S in VSMCs.

CONCLUSIONS

The compound DTCM-glutarimide suppressed GAD development by inhibiting not only alloimmune responses but also VSMC proliferation in the graft.

Protective role of bortezomib in steatotic liver ischemia/reperfusion injury through abrogation of MMP activation and YKL-40 expression

Steatotic liver grafts tolerate ischemia-reperfusion (I/R) injury poorly, contributing to poor survival following transplantation. However the molecular mechanisms leading to I/R injury still remain to be defined. We have previously reported that the protective effect of bortezomib towards inhibiting cold induced I/R injury in obese rat liver transplant model is through NF-κB down modulation. In this report using an orthotopic liver transplant (OLT) model in Zucker rats (from obese, leptin deficient donor, to lean recipient) we defined the mechanisms of steatotic liver injury, and characterized the role of bortezomib in inhibiting MMP activation and YKL-40, both of which are involved in extracellular matrix deposition and fibrosis, the key pathological features of liver allograft failure. Obese donor rats were treated with bortezomib (i.v., 0.1mg/kg immediately prior to liver procurement) to assess the role of MMP and YKL-40 in steatotic liver I/R injury. I/R injury in steatotic livers resulted in significant increases in expression of YKL-40 (9 fold), and activation of MMP-2 (15 fold)/MMP-9 (12 fold). Bortezomib treatment reduced the expression of YKL-40 and MMP to basal levels. Bortezomib also inhibited the pro-fibrotic (VEGF, HGF, bFGF, TGF-β) and pro-inflammatory (IL-1β, TNF-α and IFN-γ) cytokines significantly in comparison to untreated animals with I/R injury. These results demonstrate that I/R injury in steatotic livers following transplantation are associated with MMP activation and YKL-40 upregulation resulting in pro-fibrotic and pro-inflammatory cytokine release. Administration of the proteosomal inhibitor, bortezomib, effectively attenuated the I/R injury by inhibiting MMP and YKL-40 expression and therefore support the clinical utility of this drug in donor management for preventing I/R injury and its sequelae.

Pre-transplant antibodies to Kα1 tubulin and collagen-V in lung transplantation: clinical correlations

BACKGROUND

Immune responses to lung-associated self-antigens (SAgs) have been implicated in chronic lung allograft rejection. The goals of this study were to determine the prevalence of pre-existing antibodies (Abs) to the SAgs in pulmonary diseases and the association between pre-existing Abs to SAgs and the development of primary graft dysfunction (PGD), donor-specific antibodies (DSA), and chronic rejection.

METHODS

Pre- and post-transplant sera were analyzed from 317 lung transplant (LTx) recipients between 2000 and 2011 with diagnosis of chronic obstructive disease (n = 161), idiopathic pulmonary fibrosis (IPF; n = 50), cystic fibrosis (CF; n = 55), and others (n = 51). Samples were analyzed for Abs to SAgs by enzyme-linked immunosorbent assay, and DSA and cytokines by Luminex. The clinical diagnosis of PGD and bronchiolitis obliterans syndrome (BOS) was based on International Society for Heart and Lung Transplantation guidelines.

RESULTS

The overall prevalence of Abs to SAgs was 22.71%, including 18% in chronic obstructive pulmonary disease (p = 0.033), 34% in IPF (p = 0.0006), 29% in CF (p = 0.0023), and 19.6% in other diagnoses (p = 0.044). The incidence of PGD (88% vs 54%, p < 0.05), DSA (70% vs 45%, p < 0.01), and BOS (90% vs 38% (p < 0.001) after LTx was significantly higher in patients with pre-LTx Abs to SAgs than without. Pro-inflammatory cytokines (interleukin-1β, interleukin-17, and interferon-γ) were elevated in patients who had pre-LTx Abs to SAgs, along with a reduction in anti-inflammatory interleukin-10.

CONCLUSIONS

Patients with IPF and CF have the highest prevalence of Abs to SAgs. Patients with pre-existing Abs to SAgs are at increased risk for development of PGD, DSA, and BOS. Strategies to remove pre-existing Abs to SAgs should be considered to improve lung allograft outcome.

Interplay between immune responses to HLA and non-HLA self-antigens in allograft rejection

Recent studies strongly suggest an increasing role for immune responses against self-antigens (Ags) which are not encoded by the major histocompatibility complex in the immunopathogenesis of allograft rejection. Although, improved surgical techniques coupled with improved methods to detect and avoid sensitization against donor human leukocyte antigen (HLA) have improved the immediate and short term function of transplanted organs. However, acute and chronic rejection still remains a vexing problem for the long term function of the transplanted organ. Immediately following organ transplantation, several factors both immune and non immune mechanisms lead to the development of local inflammatory milieu which sets the stage for allograft rejection. Traditionally, development of antibodies (Abs) against mismatched donor HLA have been implicated in the development of Ab mediated rejection. However, recent studies from our laboratory and others have demonstrated that development of humoral and cellular immune responses against non-HLA self-Ags may contribute in the pathogenesis of allograft rejection. There are reports demonstrating that immune responses to self-Ags especially Abs to the self-Ags as well as cellular immune responses especially through IL17 has significant pro-fibrotic properties leading to chronic allograft failure. This review summarizes recent studies demonstrating the role for immune responses to self-Ags in allograft immunity leading to rejection as well as present recent evidence suggesting there is interplay between allo- and autoimmunity leading to allograft dysfunction.

Epithelial clara cell injury occurs in bronchiolitis obliterans syndrome after human lung transplantation

Bronchiolitis obliterans syndrome (BOS) is a condition of progressive airflow obstruction that affects a majority of lung transplant recipients and limits long-term posttransplant survival. Although epithelial injury appears central to the development of BOS, little is known regarding the specific epithelial cell types that are affected in this condition. We hypothesized that BOS would involve preferential injury to the secretory Clara cells that function in innate defense and epithelial repair. To test this hypothesis, we assessed tissue transcript, tissue protein and lung fluid protein expression of Clara cell secretory protein (CCSP), a marker for Clara cells, in lung transplant recipients with BOS, BOS-free patients and in donor controls. Our results demonstrate that CCSP tissue transcript and protein expression are significantly reduced in lung transplant recipients with BOS compared to BOS-free or donor controls. In addition, we demonstrate that CCSP protein levels are significantly reduced in the lung fluid of patients with BOS compared to BOS-free controls, in cross-sectional and longitudinal analysis. Collectively, these complementary results illustrate that BOS involves a selective alteration in the distribution and function of bronchiolar Clara cells.

T regulatory cells play a significant role in modulating MHC class I antibody-induced obliterative airway disease

The molecular mechanisms leading to the development of chronic lung allograft dysfunction following de novo development of antibodies to mismatched donor MHC remain undefined. We demonstrated that intrabronchial administration of antibodies to MHC class I resulted in induction of both innate and adaptive cellular immune responses characterized by a predominance of Th17 specific to lung associated self-antigens Kα1-tubulin and Collagen-V leading to the development of obliterative airway lesions (OAD), correlate of chronic rejection following human lung transplantation. To determine the role of regulatory T cells (Treg) in the pathogenesis of OAD, we administered anti-MHC class I to mice, in which Treg were depleted by conditional ablation of FoxP3+cells. Under this condition, we observed a threefold increase in pulmonary cellular infiltration, luminal occlusion and fibrous deposition when compared anti-MHC class I Ab administered mice maintaining FoxP3. OAD lesions were accompanied with enhanced accumulation of neutrophils along with self-antigen-specific Th17 and humoral responses. However, IL-17-blockade or adoptive transfer of Treg abrogated OAD. We conclude that Treg exerts a suppressive effect on anti-MHC induced IL-8-mediated neutrophil infiltration and innate immune responses that leads to inhibition of Th17 immune responses to lung associated self-antigens which is critical for development of OAD.

Role of antibodies to self-antigens in chronic allograft rejection: potential mechanism and therapeutic implications

Significant progress has been made in preventing acute allograft rejection following solid organ transplantation resulting in improved allograft survival. However, long term function still remains disappointing primarily due to chronic allograft rejection. Alloimmune responses primarily defined by the development of antibodies (Abs) to donor mismatched major histocompatibility antigens during the post-transplantation period have been strongly correlated to the development of chronic rejection. In addition, recent studies have demonstrated an important role for autoimmunity including the development of Abs to organ specific self-antigens in the pathogenesis of chronic allograft rejection. Based on this, a new paradigm has evolved indicating a possible cross-talk between the alloimmune responses and autoimmunity leading to chronic rejection. In this review, we will discuss the emerging concept for the role of cellular and humoral immune responses to self-antigens in the immunopathogenesis of chronic allograft rejection which has the potential to develop new strategies for the prevention and/or treatment of chronic rejection.

An important role for autoimmunity in the immunopathogenesis of chronic allograft rejection

Organ transplantation is the treatment of choice for patients with end-stage organ dysfunction. In spite of advances in understanding of donor and recipient physiology, organ preservation, operative techniques and immunosuppression, long-term graft survival still remains a major problem primarily due to chronic rejection. Alloimmune responses to mismatched major histocompatibility antigens have been implicated as an important factor leading to rejection. However, there is increasing evidence pointing towards cross-talk between the alloimmune and autoimmune responses creating a local inflammatory milieu, which eventually leads to fibrosis and occlusion of the lumen in the transplanted organ i.e. chronic rejection. In this review, we will discuss recent studies and emerging concepts for the interdependence of alloimmune and autoimmune responses in the immunopathogenesis of chronic allograft rejection. The role of autoimmunity in the development of chronic rejection is an intriguing and exciting area of research in the field of solid-organ transplantation with a significant potential to develop novel therapeutic strategies towards preventing chronic allograft rejection.

Immune responses to self-antigens (autoimmunity) in allograft rejection

Many lung, heart, and kidney transplant recipients with clinically as well as pathologically diagnosed chronic rejection don't have detectable antibodies directed to the mismatched donor HLA in their sera. This has led to the hypothesis that antibody responses to other tissue-restricted antigens may contribute to the development of chronic rejection. Development of immune responses to self-antigens has been described following all solid organ transplantations. Studies have further presented evidence for a significant cross talk between the alloimmune and autoimmune responses. Experimental results demonstrate that blocking of the immune responses to self-antigens may prevent chronic rejection. In this review, we present recent evidence for an important role of immune responses to self-antigens in the development of chronic rejection following transplantation. Further, we discuss the implications of these findings in developing new therapeutic strategies towards preventing or treating chronic rejection following transplantation.

HIF-1α signaling by airway epithelial cell K-α1-tubulin: role in fibrosis and chronic rejection of human lung allografts

Long term survival of the human lung allografts are hindered by chronic rejection, manifested clinically as bronchiolitis obliterans syndrome (BOS). We previously demonstrated significant correlation between the development of antibodies (Abs) to K-α1-tubulin (Kα1T) and BOS. In this study, we investigated the molecular basis for fibrinogenesis mediated by ligation of Kα1T expressed on airway epithelial cells by its specific Abs. Using RT-PCR we demonstrate that normal human bronchial epithelial (NHBE) cells upon ligation of Kα1T with specific Abs caused upregulation of pro-fibrotic growth factors. Western blot analysis of NHBE incubated with Kα1T Abs increased hypoxia inducible factor (HIF-1α). Kα1T Ab-mediated growth factor expression is dependent on HIF-1α as inhibition of HIF-1α returned fibrotic growth factor expression to basal levels. In conclusion, we propose that HIF-1α -mediated upregulation of fibrogenic growth factors induced by ligation of Kα1T Abs is critical for development of fibrosis leading to chronic rejection of lung allograft.

A role for antibodies to human leukocyte antigens, collagen-V, and K-α1-Tubulin in antibody-mediated rejection and cardiac allograft vasculopathy

BACKGROUND

We determined the role of donor-specific antibodies (DSA) and antibodies (Abs) to self-antigens, collagen-V (Col-V), and K-α1-Tubulin (KAT) in pathogenesis of acute antibody-mediated rejection (AMR) and cardiac allograft vasculopathy (CAV) after human heart transplantation (HTx).

METHODS

One hundred thirty-seven HTx recipients, with 60 early period (≤ 12 months) and 77 late period (>12 months), were enrolled in this study. Circulating DSA was determined using LUMINEX. Abs against Col-I, II, IV, V, and KAT were measured using ELISA. Frequency of CD4+T helper cells (CD4+Th) secreting interferon (IFN)-γ, interleukin (IL)-5, -10, or -17 specific to self-antigens were determined using Enzyme Linked Immunosorbent Spot assay.

RESULTS

A significant association between AMR and DSA was demonstrated. Development of DSA in AMR patients correlated well with the development of auto-Abs to Col-V (AMR[+]: 383 ± 72 μg/mL, AMR[-]: 172 ± 49 μg/mL, P=0.033) and KAT (AMR[+]: 252 ± 49 μg/mL, AMR[-]: 61 ± 21 μg/mL, P=0.014). Patients who developed AMR demonstrated increased frequencies of CD4+Th secreting IFN-γ and IL-5 with reduction in IL-10 specific for Col-V/KAT. Patients diagnosed with CAV also developed DSA and auto-Abs to Col-V (CAV[+]: 835 ± 142 μg/mL, CAV[-]: 242 ± 68 μg/mL, P=0.025) and KAT (CAV[+]: 768 ± 206 μg/mL, CAV[-]: 196 ± 72 μg/mL, P=0.001) with increased frequencies of CD4+Th secreting IL-17 with reduction in IL-10 specific for Col-V/KAT. CONCLUSIONS.: Development of Abs to human leukocyte antigens and self-antigens are associated with increases in CD4+Th secreting IFN-γ and IL-5 in AMR and IL-17 in CAV, with reduction in CD4+Th secreting IL-10 in both AMR and CAV.