Kidney injury-mediated disruption of intestinal lymphatics involves dicarbonyl-modified lipoproteins.

Kidney disease affects intestinal structure and function. Although intestinal lymphatics are central in absorption and remodeling of dietary and synthesized lipids/lipoproteins, little is known about how kidney injury impacts the intestinal lymphatic network, or lipoproteins transported therein. To study this, we used puromycin aminoglycoside-treated rats and NEP25 transgenic mice to show that proteinuric injury expanded the intestinal lymphatic network, activated lymphatic endothelial cells and increased mesenteric lymph flow. The lymph was found to contain increased levels of cytokines, immune cells, and isolevuglandin (a highly reactive dicarbonyl) and to have a greater output of apolipoprotein AI. Plasma levels of cytokines and isolevuglandin were not changed. However, isolevuglandin was also increased in the ileum of proteinuric animals, and intestinal epithelial cells exposed to myeloperoxidase produced more isolevuglandin. Apolipoprotein AI modified by isolevuglandin directly increased lymphatic vessel contractions, activated lymphatic endothelial cells, and enhanced the secretion of the lymphangiogenic promoter vascular endothelial growth factor-C by macrophages. Inhibition of isolevuglandin synthesis by a carbonyl scavenger reduced intestinal isolevuglandin adduct level and lymphangiogenesis. Thus, our data reveal a novel mediator, isolevuglandin modified apolipoprotein AI, and uncover intestinal lymphatic network structure and activity as a new pathway in the crosstalk between kidney and intestine that may contribute to the adverse impact of kidney disease on other organs.

Intestinal Lymph Collection via Cannulation of the Mesenteric Lymphatic Duct in Mice.

BACKGROUND: We have optimized a technique for cannulation of mesenteric lymph duct (MLD) in mice. Mice have low rates of intestinal lymph production; the MLDs are smaller and associated with fragile vasculature. Previous protocols for lymph collection based on the open lymph fistula model were associated with low success rates in mice. Bariatric surgery procedures worsen success rates due to postoperative adhesions and GI rearrangement. We have used this procedure to collect mesenteric lymph from mice undergoing bile diversion from gall bladder to ileum (GB-IL). HYPOTHESIS: We hypothesize that peptide YY (PYY) levels in mesenteric lymph will increase following nutrient delivery in mice undergoing bile diversion from gall bladder to ileum (GB-IL). METHODS AND RESULTS: We observe that cannulation of the MLD using a needled-catheter maintains lymph vessel integrity, prevents excessive lymph leakage, and is less traumatic, leading to high success rates (>95%). PYY levels in mesenteric lymph after GB-IL were significantly higher post nutrient infusion. The procedure takes approximately 20 min; small rodent surgical experience and practice are required for success. CONCLUSIONS: Intestinal lymph can be collected from mice, including those undergoing bariatric surgical procedures with high success rates by cannulation of the mesenteric lymph duct.

Role of Bile Acids and GLP-1 in Mediating the Metabolic Improvements of Bariatric Surgery.

BACKGROUND & AIMS: Bile diversion to the ileum (GB-IL) has strikingly similar metabolic and satiating effects to Roux-en-Y gastric bypass (RYGB) in rodent obesity models. The metabolic benefits of these procedures are thought to be mediated by increased bile acids, although parallel changes in body weight and other confounding variables limit this interpretation. METHODS: Global G protein-coupled bile acid receptor-1 null (Tgr5-/-) and intestinal-specific farnesoid X receptor null (FxrΔ/E) mice on high-fat diet as well as wild-type C57BL/6 and glucagon-like polypeptide 1 receptor deficient (Glp-1r-/-) mice on chow diet were characterized following GB-IL. RESULTS: GB-IL induced weight loss and improved oral glucose tolerance in Tgr5-/-, but not FxrΔ/E mice fed a high-fat diet, suggesting a role for intestinal Fxr. GB-IL in wild-type, chow-fed mice prompted weight-independent improvements in glycemia and glucose tolerance secondary to augmented insulin responsiveness. Improvements were concomitant with increased levels of lymphatic GLP-1 in the fasted state and increased levels of intestinal Akkermansia muciniphila. Improvements in fasting glycemia after GB-IL were mitigated with exendin-9, a GLP-1 receptor antagonist, or cholestyramine, a bile acid sequestrant. The glucoregulatory effects of GB-IL were lost in whole-body Glp-1r-/- mice. CONCLUSIONS: Bile diversion to the ileum improves glucose homeostasis via an intestinal Fxr-Glp-1 axis. Altered intestinal bile acid availability, independent of weight loss, and intestinal Akkermansia muciniphila appear to mediate the metabolic changes observed after bariatric surgery and might be manipulated for treatment of obesity and diabetes.

Enhanced immunosuppression improves early allograft function in a porcine kidney transplant model of donation after circulatory death.

It remains controversial whether renal allografts from donation after circulatory death (DCD) have a higher risk of acute rejection (AR). In the porcine large animal kidney transplant model, we investigated the AR and function of DCD renal allografts compared to the non-DCD renal allografts and the effects of increased immunosuppression. We found that the AR was significantly increased along with elevated MHC-I expression in the DCD transplants receiving low-dose immunosuppression; however, AR and renal function were significantly improved when given high-dose immunosuppressive therapy postoperatively. Also, high-dose immunosuppression remarkably decreased the mRNA levels of ifn-g, il-6, tgf-b, il-4, and tnf-a in the allograft at day 5 and decreased serum cytokines levels of IFN-g and IL-17 at day 4 and day 5 after operation. Furthermore, Western blot analysis showed that higher immunosuppression decreased phosphorylation of signal transducer and activator of transcription 3 and nuclear factor kappa-light-chain-enhancer of activated B cells-p65, increased phosphorylation of extracellular-signal-regulated kinase, and reduced the expression of Bcl-2-associated X protein and caspase-3 in the renal allografts. These results suggest that the DCD renal allograft seems to be more vulnerable to AR; enhanced immunosuppression reduces DCD-associated AR and improves early allograft function in a preclinical large animal model.

Anti-CD47 monoclonal antibody therapy reduces ischemia-reperfusion injury of renal allografts in a porcine model of donation after cardiac death.

We investigated whether blockade of the CD47 signaling pathway could reduce ischemia-reperfusion injury (IRI) of renal allografts donated after cardiac death (DCD) in a porcine animal model of transplantation. Renal allografts were subjected to 30 minutes of warm ischemia, 3.5 hours of cold ischemia, and then perfused with a humanized anti-CD47 monoclonal antibody (CD47mAb) in the treatment group or HTK solution in the control group (n = 4/group). The animals were euthanized five days after transplantation. At the time of reperfusion, indocyanine green-based in vivo imaging showed that CD47mAb-treated organs had greater and more uniform reperfusion. On post-transplant days 3-5, the treatment group had lower values compared to the control for creatinine and blood urea nitrogen. Histological examination of allograft tissues showed a significant decrease of acute tubular injury in the CD47mAb-treated group compared to control. Compared to the control group, CD47mAb treatment significantly decreased genes expression related to oxidative stress (sod-1, gpx-1, and txn), the inflammatory response (il-2, il-6, inf-g, and tgf-b), as well as reduced protein levels of BAX, Caspase-3, MMP2, and MMP9. These data demonstrate that CD47mAb blockade decreases IRI and subsequent tissue injury in DCD renal allografts in a large animal transplant model.

Development of a normothermic extracorporeal liver perfusion system toward improving viability and function of human extended criteria donor livers.

Donor organ shortages have led to an increased interest in finding new approaches to recover organs from extended criteria donors (ECD). Normothermic extracorporeal liver perfusion (NELP) has been proposed as a superior preservation method to reduce ischemia/reperfusion injury (IRI), precondition suboptimal grafts, and treat ECD livers so that they can be successfully used for transplantation. The aim of this study was to investigate the beneficial effects of a modified NELP circuit on discarded human livers. Seven human livers that were rejected for transplantation were placed on a modified NELP circuit for 8 hours. Perfusate samples and needle core biopsies were obtained at hourly intervals. A defatting solution that contained exendin-4 (50 nM) and L-carnitine (10 mM) was added to the perfusate for 2 steatotic livers. NELP provided normal temperature, electrolytes, and pH and glucose levels in the perfusate along with physiological vascular flows and pressures. Functional, biochemical, and microscopic evaluation revealed no additional injuries to the grafts during NELP with an improved oxygen extraction ratio (>0.5) and stabilized markers of hepatic injury. All livers synthesized adequate amounts of bile and coagulation factors. We also demonstrated a mild reduction (10%) of macroglobular steatosis with the use of the defatting solution. Histology demonstrated normal parenchymal architecture and a minimal to complete lack of IRI at the end of NELP. In conclusion, a modified NELP circuit preserved hepatocyte architecture, recovered synthetic functions, and hepatobiliary parameters of ECD livers without additional injuries to the grafts. This approach has the potential to increase the donor pool for clinical transplantation. Liver Transplantation 22 979-993 2016 AASLD.

Novel strategy to decrease reperfusion injuries and improve function of cold-preserved livers using normothermic ex vivo liver perfusion machine.

Normothermic extracorporeal liver perfusion (NELP) can decrease ischemia/reperfusion injury to the greatest degree when cold ischemia time is minimized. Warm perfusion of cold-stored livers results in hepatocellular damage, sinusoidal endothelial cell (SEC) dysfunction, and Kupffer cell activation. However, the logistics of organ procurement mandates a period of cold preservation before NELP. The aim of this study was to determine the beneficial effects of gradual rewarming of cold-stored livers by placement on NELP. Three female porcine livers were used for each group. In the immediate NELP group, procured livers were immediately placed on NELP for 8 hours. In the cold NELP group, livers were cold-stored for 4 hours followed by NELP for 4 hours. In rewarming groups, livers were cold-stored for 4 hours, then gradually rewarmed in different durations to 38°C and kept on NELP for an additional 4 hours. For comparison purposes, the last 4 hours of NELP runs were considered to be the evaluation phase. Immediate NELP livers had significantly lower concentrations of liver transaminases, hyaluronic acid, and ß-galactosidase and had higher bile production compared to the other groups. Rewarming livers had significantly lower concentrations of hyaluronic acid and ß-galactosidase compared to the cold NELP livers. In addition, there was a significant decline in international normalized ratio values, improved bile production, reduced biliary epithelial cell damage, and improved cholangiocyte function. Thus, if a NELP machine is not available at the procurement site and livers will need to undergo a period of cold preservation, a gradual rewarming protocol before NELP may greatly reduce damages that are associated with reperfusion. In conclusion, gradual rewarming of cold-preserved livers upon NELP can minimize the hepatocellular damage, Kupffer cell activation, and SEC dysfunction.

CD47 blockade reduces ischemia/reperfusion injury and improves survival in a rat liver transplantation model.

Orthotopic liver transplantation (OLT) remains the standard treatment option for nonresponsive liver failure. Because ischemia/reperfusion injury (IRI) is an important impediment to the success of OLT, new therapeutic strategies are needed to reduce IRI. We investigated whether blocking the CD47/thrombospondin-1 inhibitory action on nitric oxide signaling with a monoclonal antibody specific to CD47 (CD47mAb400) would reduce IRI in liver grafts. Syngeneic OLT was performed with Lewis rats. Control immunoglobulin G or CD47mAb400 was administered to the donor organ at procurement or to both the organ and the recipient at the time of transplant. Serum transaminases, histological changes of the liver, and animal survival were assessed. Oxidative stress, inflammatory responses, and hepatocellular damage were also quantified. A significant survival benefit was not achieved when CD47mAb400 was administered to the donor alone. However, CD47mAb400 administration to both the donor and the recipient increased animal survival afterward. The CD47mAb400-treated group showed lower serum transaminases, bilirubin, oxidative stress, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining, caspase-3 activity, and proinflammatory cytokine expression of tumor necrosis factor α, interleukin-1ß, and interleukin-6. Thus, CD47 blockade with CD47mAb400 administered both to the donor and the recipient reduced liver graft IRI in a rat liver transplantation model. This may translate to decreased liver dysfunction and increased survival of liver transplant recipients.

Botulinum Injection Into the Proximal Intestinal Wall of Diet-Induced Obese Mice Leads to Weight Loss and Improves Glucose and Fat Tolerance.

Botulinum neurotoxin (available commercially as BOTOX) has been used successfully for treatment of several neuromuscular disorders, including blepharospasm, dystonia, spasticity, and cerebral palsy in children. Our data demonstrate that injection of Botox into the proximal intestinal wall of diet-induced obese (DIO) mice induces weight loss and reduces food intake. This was associated with amelioration of hyperglycemia, hyperlipidemia, and significant improvement of glucose tolerance without alteration of energy expenditure. We also observed accelerated gastrointestinal transit and significant reductions in glucose and lipid absorption, which may account, at least in part, for the observed weight loss and robust metabolic benefits, although possible systemic effects occurring as a consequence of central and/or peripheral signaling cannot be ignored. The observed metabolic benefits were found to be largely independent of weight loss, as demonstrated by pair-feeding experiments. Effects lasted ∼8 weeks, for as long as the half-life of Botox as reported in prior rodent studies. These results have valuable clinical implications. If the observed effects are translatable in humans, this approach could lay the foundation for therapeutic approaches geared toward robust and sustained weight loss, mimicking some of the benefits of bariatric operations without its cost and complications.

Improving Liver Graft Function Using CD47 Blockade in the Setting of Normothermic Machine Perfusion.

BACKGROUND: Toward the goal of using more livers for transplantation, transplant centers are looking to increase the use of organs from "marginal" donors. Livers from these donors, however, have been shown to be more susceptible to preservation and reperfusion injury. METHODS: Using a porcine model of donation after circulatory death, we studied the use of antibody-mediated CD47 blockade to further improve liver graft function undergoing normothermic machine perfusion. Livers from 20 pigs (5 per group) were brought under either 30 or 60 min of warm ischemia time followed by the administration of CD47 monoclonal antibody (CD47mAb) treatment or immunoglobulin G control antibodies and 6 h of normothermic extracorporeal liver perfusion. RESULTS: After 6 h of normothermic extracorporeal liver perfusion, CD47mAb-treated livers with 30 or 60 min warm ischemia time had significantly lower alanine transaminase levels and higher bile production compared with their respective control groups. Blockade of the CD47 signaling pathway resulted in significantly lower thrombospondin-1 protein levels, lower expression of caspase-3, and higher expression of phosphorylated extracellular signal-regulated kinase. CONCLUSIONS: These findings suggested that CD47mAb treatment decreases ischemia/reperfusion injury through CD47/thrombospondin-1 signaling downregulation and the presence of necrosis/apoptosis after reperfusion and could increase liver regeneration during normothermic perfusion of the liver.

Development of a novel murine model of lymphatic metastasis.

Current laboratory models of lymphatic metastasis generally require either genetically modified animals or are technically challenging. Herein, we have developed a robust protocol for the induction of intralymphatic metastasis in wild-type mice with reproducible outcomes. To determine an optimal injection quantity and timeline for tumorigenesis, C57Bl/6 mice were injected directly into the mesenteric lymph duct (MLD) with varying numbers of syngeneic murine colon cancer cells (MC38) or gastric cancer cells (YTN16) expressing GFP/luciferase and monitored over 2-4 weeks. Tumor growth was tracked via whole-animal in vivo bioluminescence imaging (IVIS). Our data indicate that the injection of tumor cells into the MLD is a viable model for lymphatic metastasis as necropsies revealed large tumor burdens and metastasis in regional lymph nodes. This protocol enables a closer study of the role of lymphatics in cancer metastasis and opens a window for the development of novel approaches for treatment of metastatic diseases.

Bile acids and bariatric surgery.

Bariatric surgery, specifically Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), are the most effective and durable treatments for morbid obesity and potentially a viable treatment for type 2 diabetes (T2D). The resolution rate of T2D following these procedures is between 40 and 80% and far surpasses that achieved by medical management alone. The molecular basis for this improvement is not entirely understood, but has been attributed in part to the altered enterohepatic circulation of bile acids. In this review we highlight how bile acids potentially contribute to improved lipid and glucose homeostasis, insulin sensitivity and energy expenditure after these procedures. The impact of altered bile acid levels in enterohepatic circulation is also associated with changes in gut microflora, which may further contribute to some of these beneficial effects. We highlight the beneficial effects of experimental surgical procedures in rodents that alter bile secretory flow without gastric restriction or altering nutrient flow. This information suggests a role for bile acids beyond dietary fat emulsification in altering whole body glucose and lipid metabolism strongly, and also suggests emerging roles for the activation of the bile acid receptors farnesoid x receptor (FXR) and G-protein coupled bile acid receptor (TGR5) in these improvements. The limitations of rodent studies and the current state of our understanding is reviewed and the potential effects of bile acids mediating the short- and long-term metabolic improvements after bariatric surgery is critically examined.

Neoadjuvant Locoregional Therapy and Recurrent Hepatocellular Carcinoma after Liver Transplantation.

BACKGROUND: Neoadjuvant locoregional therapies (LRTs) have been widely used to reduce tumor burden or to downstage hepatocellular carcinoma (HCC) before orthotopic liver transplantation (OLT). We examined the impact of LRT response on HCC recurrence after OLT. STUDY DESIGN: We performed a retrospective study of 384 patients with HCC treated by OLT. Tumor necrosis was determined by pathologic evaluation. The vascular and lymphatic vessels were localized by immunofluorescence staining in formalin-fixed, paraffin-embedded tissue; expressions of vascular endothelial growth factor receptor (VEGFR)-2 and VEGFR-3 were analyzed by Western blot. Plasma vascular endothelial growth factor (VEGF)-A and VEGF-C levels of a consecutive cohort of 171 HCC patients were detected by ELISA. RESULTS: Of the 384 patients with HCC, 268 had undergone pretransplantation neoadjuvant LRTs. Patients with no tumor necrosis (n = 58; 5.2% recurrence) or complete tumor necrosis (n = 70; 6.1% recurrence) had significantly lower 5-year recurrence rates than those with partial tumor necrosis (n = 140; 22.6% recurrence; p < 0.001). Lymphatic metastases were significantly more numerous in patients with partial tumor necrosis than in those without tumor necrosis after OLT (p < 0.001). With immunofluorescence staining of peritumor zone, lymphatics were visualized around partially necrotic tumors, but not around tumors without necrosis. Plasma levels of VEGF-A and VEGF-C were elevated significantly in patients with evidence of tumor necrosis (n = 102) compared with those without necrosis (n = 69; p < 0.001). By Western blot, VEGFR-2 and VEGFR-3 expression in the peritumoral tissue associated with partially necrotic tumors was significantly higher than in peritumoral tissue of non-necrosis tumors (n = 3/group, p < 0.020 and p < 0.006, respectively). CONCLUSIONS: Locoregional therapy-induced or spontaneous partially necrotic HCC was associated with increased risk of lymphatic metastases compared with tumors with no or complete tumor necrosis. Anti-lymphangiogenic agents with neoadjuvant LRTs can decrease the pattern of lymphatic metastasis after OLT.

Attenuation of Ischemia-Reperfusion Injury and Improvement of Survival in Recipients of Steatotic Rat Livers Using CD47 Monoclonal Antibody.

BACKGROUND: Despite the efficacy of orthotopic liver transplantation in the treatment of end-stage liver diseases, its therapeutic utility is severely limited by the availability of donor organs. The ability to rehabilitate marginal organs, such as steatotic allografts, has the potential to address some of the supply limitations of available organs for transplantation. Steatotic livers are more susceptible to ischemia-reperfusion injury (IRI), which is exacerbated by the thrombospondin-1/CD47 pathway through inhibition of nitric oxide signaling. We postulated that CD47 blockade with a monoclonal antibody specific to CD47, clone 400 (CD47mAb400) may reduce the extent of IRI in steatotic liver allografts. METHODS: Orthotopic liver transplantation was performed using steatotic liver grafts from Zucker rats transplanted into lean recipients. Control IgG or the CD47mAb400 was administered to the donor livers at procurement. Serum transaminases, histological changes, and animal survival were assessed. Hepatocellular damage, oxidative and nitrosative stress, and inflammation were also quantified. RESULTS: Administration of CD47mAb400 to donor livers increased recipient survival and resulted in significant reduction of serum transaminases, bilirubin, triphosphate nick-end labeling staining, caspase-3 activity, oxidative and nitrosative stresses, and proinflammatory cytokine expression of TNF-α, IL-6 and IL-1ß. CONCLUSIONS: We conclude that administration of CD47mAb400 to donor grafts may reduce IRI through CD47 blockade to result in improved function of steatotic liver allografts and increased survival of recipients and represent a novel strategy to allow the use of livers with higher levels of steatosis.

Synergistic effect of pro-inflammatory TNFα and IL-17 in periostin mediated collagen deposition: potential role in liver fibrosis.

BACKGROUND: The pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-17, have been implicated in the pathogenesis of liver fibrosis. In this study, we investigated the role of TNFα and IL-17 toward induction of profibrotic factor, periostin. METHODS: HepG2 cells were cultured and treated with inflammatory cytokines, TNFα and IL-17. Computational promoter sequence analysis of the periostin promoter was performed to define the putative binding sites for transcription factors. Transcription factors were analyzed by Western blot and Chromatin Immunoprecipitation. Periostin and transcription factor expression analysis was performed by RT-PCR, Western blot, and fluorescence microscopy. Type I collagen expression from fibroblast cultures was analyzed by Western blot and Sircol soluble collagen assay. RESULTS: Activation of HepG2 Cells with TNFα and IL-17 enhanced the expression of periostin (3.5 and 4.4 fold, respectively p<0.05) compared to untreated cells. However, combined treatment with both TNFα and IL-17 at similar concentration demonstrated a 13.3 fold increase in periostin (p<0.01), thus suggesting a synergistic role of these cytokines. Periostin promoter analysis and specific siRNA knock-down revealed that TNFα induces periostin through cJun, while IL-17 induced periostin via STAT-3 signaling mechanisms. Treatment of the supernatant from the cytokine activated HepG2 cells on fibroblast cultures induced enhanced expression of type I collagen (>9.1 fold, p<0.01), indicative of a direct fibrogenic effect of TNFα and IL-17. CONCLUSION: TNFα and IL-17 induced fibrogenesis through cJun and STAT-3 mediated expression of profibrotic biomarker, periostin. Therefore, periostin might serve as a novel biomarker in early diagnosis of liver fibrosis.

Normothermic extracorporeal liver perfusion for donation after cardiac death (DCD) livers.

BACKGROUND: The susceptibility of extended criteria livers to ischemia reperfusion injury is a major obstacle in organ cold preservation. Normothermic extracorporeal liver perfusion (NELP) has been investigated to reduce ischemic damage, restore physiologic function, and assess viability of the liver prior to transplant. The goal of this study is to compare physiological parameters of livers maintained continuously on NELP to those preserved in cold solution. METHODS: Livers from 9 female landrace pigs were subjected to either 20 minutes (W20-NELP), 40 minutes (W40-NELP), or 60 minutes (W60-NELP) of warm ischemia followed by 6 hours of NELP followed by a 2-hour NELP evaluation phase. This was compared with 3 livers subjected to 40 minutes of warm ischemia time followed by 6 hours of cold storage (W40-Cold) and a 2-hour NELP evaluation phase. Groups were compared with the 2-way analysis of variance test. RESULTS: NELP stabilized transaminases accompanied by significant improvement in bile production and decline in lactate and INR values in all W-NELP groups. Histologic analysis demonstrated significant improvement from 0 hour (mild-to-moderate sinusoidal dilation and zone 3 necrosis) to the end of the NELP run (minimal necrosis and mild IRI). Comparison of W40-NELP and W40-Cold revealed greater bile production and oxygen extraction ratio in W40-NELP. In contrast, markers of cellular and functional damage were increased in the W40-Cold group. CONCLUSION: NELP improves metabolic and functional parameters of livers with either short or extended warm ischemia times compared with livers subjected to comparable cold ischemia times.

Antibody mediated therapy targeting CD47 inhibits tumor progression of hepatocellular carcinoma.

Human hepatocellular carcinoma (HCC) has a high rate of tumor recurrence and metastasis, resulting in shortened survival times. The efficacy of current systemic therapies for HCC is limited. In this study, we used xenograft tumor models to investigate the use of antibodies that block CD47 and inhibit HCC tumor growth. Immunostaining of tumor tissue and HCC cell lines demonstrated CD47 over-expression in HCC as compared to normal hepatocytes. Macrophage phagocytosis of HCC cells was increased after treatment with CD47 antibodies (CD47mAbs) that block CD47 binding to SIRPα. Further, CD47 blockade inhibited tumor growth in both heterotopic and orthotopic models of HCC, and promoted the migration of macrophages into the tumor mass. Our results demonstrate that targeting CD47 by specific antibodies has potential immunotherapeutic efficacy in human HCC.

Role of defensins in the pathogenesis of chronic lung allograft rejection.

Chronic rejection predominantly manifested as bronchiolitis obliterans syndrome (BOS), still remains a major problem affecting long-term outcomes in human lung transplantation (LTx). Donor specific antibodies (DSA) and infiltration of neutrophils in the graft have been associated with the development of BOS. This study determines the role of defensins, produced by neutrophils, and its interaction with α-1-antitrypsin (AAT) towards induction of airway inflammation and fibrosis which are characteristic hallmarks of BOS. Bronchoalveolar lavage (BAL) and serum from LTx recipients, BOS+ (n=28), BOS- (n=26) and normal healthy controls (n=24) were analyzed. Our results show that BOS+ LTx recipients had higher α-defensins (HNP1-3) and ß-defensin2 HBD2 concentration in BAL and serum compared to BOS-DSA-recipients and normal controls (p=0.03). BOS+ patients had significantly lower serum AAT along with higher circulating concentration of HNP-AAT complexes in BAL (p=0.05). Stimulation of primary small airway epithelial cells (SAECs) with HNPs induced expression of HBD2, adhesion molecules (ICAM and VCAM), cytokines (IL-6, IL-1ß, IL-13, IL-8 and MCP-1) and growth-factor (VEGF and EGF). In contrast, anti-inflammatory cytokine, IL-10 expression decreased 2-fold (p=0.002). HNPs mediated SAEC activation was completely abrogated by AAT. In conclusion, our results demonstrates that neutrophil secretory product, α-defensins, stimulate ß-defensin production by SAECs causing upregulation of pro-inflammatory and pro-fibrotic signaling molecules. Hence, chronic stimulation of airway epithelial cells by defensins can lead to inflammation and fibrosis the central events in the development of BOS following LTx.

Role of alloimmunity and autoimmunity in allograft rejection.

Pathophysiology of chronic rejection strongly supports that inflammation and subsequent tissue remodeling during the post-transplant period cause exposure of cryptic self-antigens (SAgs) or their determinants within the graft, which, along with a subsequent cytokine response, leads to loss of peripheral tolerance. These events lead to the activation of cell-mediated immunity towards development of de novo immune responses to SAgs. There is also evidence for a role for interplay between allo- and autoimmunity in the development of chronic rejection. Experimental results using murine models of Obliterative Airway Disease (OAD) akin to chronic lung allograft rejection have clearly demonstrated that autoimmune responses to Collagen V (ColV) and K-alpha 1 Tubulin (KalT) were induced by administration of antibodies (Abs) against class I major histocompatibility complex antigens. Further, inhibition of interleukin (IL)-17 abrogated the autoimmune response and development of OAD. This shows an important relationship between alloimmunity, autoimmunity to SAgs such as KalT, and a significant role for IL-17 pathway of immune activation. Recent reports demonstrate that in addition to lung transplant recipients, kidney transplant recipients diagnosed with transplant glomerulopathy can develop de novo Abs to Sags, including Col-IV and fibronectin and heart transplant recipients can develop immune responses to cardiac myosin and vimentin. Abs to SAgs were identified frequently with donor specific anti-human leukocyte antigen antibodies, supporting the concept of crosstalk between auto- and alloimmunity. The increased frequency of SAg specific interferon-gamma and IL-17 cells with reduction in IL-10 demonstrates tolerance breakdown to SAgs which may play a significant role in the pathogenesis of chronic rejection.