Role of adhesion molecules and dendritic cells in rat hepatic/renal ischemia-reperfusion injury and anti-adhesive intervention with anti-P-selectin lectin-EGF domain monoclonal antibody

Elucidating the molecular pathways and immune system transcriptome during ischemia-reperfusion injury in renal transplantation

Ischemia reperfusion injury (IRI) is a major challenge for renal transplantation. This study was performed to explore the mechanisms and potential molecular targets involved in renal IRI. In this study, the gene datasets GSE43974 and GSE126805 from the Gene Expression Omnibus database, which include ischemic and reperfused renal specimens, were analyzed to determine differentially expressed genes (DEGs). Gene ontology annotations, Kyoto Encyclopedia of Genes and Genomes analysis, and gene set enrichment analysis were performed to determine the pathways that are significantly enriched during ischemia and reperfusion. We also determined the microenvironment cell types xCell and performed correlation analyses to reveal the relationship between the molecular pathways and microenvironment cell infiltration. We found 77 DEGs (76 up- and 1 downregulated) and 323 DEGs (312 up- and 11 downregulated) in the GSE43974 and GSE126805 datasets, respectively. Similar signaling pathway enrichment patterns were observed between the two datasets. The combined analyses demonstrate that the NOD-like receptor signaling pathway and its two downstream signaling pathways, MAPK and NF-kβ, are the major significantly enriched pathways. The xCell analysis identified immune cells that are significantly changed after reperfusion, including hematopoietic stem cells, M2 macrophages, monocytes, Treg cells, conventional dendritic cells, and pro B-cells. Enrichment scores of the NOD-like receptor signaling pathway and its downstream pathways during IRI was significantly correlated with the change levels in class-switched memory B-cell and hematopoietic stem cells in both datasets. These data reveal the important role of the NOD-like receptor signaling pathway during IRI, and the close relationship between this pathway and infiltration of specific immune cell types. Our data provide compelling insights into the pathogenesis and potential therapeutic targets for renal IRI.

The role of dendritic cells regulated by HMGB1/TLR4 signalling pathway in myocardial ischaemia reperfusion injury

Inflammatory response plays an important role in ischaemia reperfusion injury (IRI) through a variety of inflammatory cells. Apart from neutrophils, macrophages and lymphocytes, the role of dendritic cells (DCs) in IRI has been noticed. The study was aimed at investigating whether the high‐mobility group protein box‐1/toll like receptor 4 (HMGB1/TLR4) signalling pathway regulate the migration, adhesion and aggregation of DCs to the myocardium, induce DCs activation and maturation, stimulate the expression of surface costimulatory molecules and participate in myocardial IRI. In vivo, migration, adhesion, and aggregation of DCs was enhanced; the expression of peripheral blood DCs CD80 and CD86, myocardial adhesion molecules were increased; and the infarct size was increased during myocardial ischaemia reperfusion injury myocardial ischemic/reperfusion injury (MI/RI). These responses induced by MI/RI were significantly inhibited by HMGB1 specific neutralizing antibody treatment. Cellular experiments confirmed that HMGB1 promoted the release of inflammatory cytokines through TLR4/MyD88/NF‐κB, upregulated CD80 and CD86 expression, mediated the damage of cardiomyocytes and accelerated the apoptosis. Our results indicate that DCs activation and maturation, stimulate the expression of surface costimulatory molecules by promoting the release of inflammatory factors through NF‐κB pathway and participate in myocardial IRI.

Rictor deficiency in dendritic cells exacerbates acute kidney injury

Dendritic cells (DCs) are critical initiators of innate immunity in the kidney and orchestrate inflammation following ischemia-reperfusion injury. The role of the mammalian/mechanistic target of rapamycin (mTOR) in the pathophysiology of renal ischemia-reperfusion injury has been characterized. However, the influence of DC-based alterations in mTOR signaling is unknown. To address this, bone marrow-derived mTORC2-deficient (Rictor^-/-) DCs underwent hypoxia-reoxygenation and then analysis by flow cytometry. Adoptive transfer of wild-type or Rictor^-/- DC to C57BL/6 mice followed by unilateral or bilateral renal ischemia-reperfusion injury (20 min ischemia) was used to assess their in vivo migratory capacity and influence on tissue injury. Age-matched male DC-specific Rictor^-/- mice or littermate controls underwent bilateral renal ischemia-reperfusion, followed by assessment of renal function, histopathology, and biomolecular and cell infiltration analysis. Rictor^-/- DCs expressed more costimulatory CD80/CD86 but less coinhibitory programmed death ligand 1 (PDL1), a pattern that was enhanced by hypoxia-reoxygenation. They also demonstrated enhanced migration to the injured kidney and induced greater tissue damage. Following ischemia-reperfusion, Rictor^-/- DC mice developed higher serum creatinine levels, more severe histological damage, and greater proinflammatory cytokine production compared to littermate controls. Additionally, a greater influx of both neutrophils and T cells was seen in Rictor^-/- DC mice, along with CD11c⁺MHCII⁺CD11b^hiF4/80⁺ renal DC, that expressed more CD86 but less PDL1. Thus, DC-targeted elimination of Rictor enhances inflammation and migratory responses to the injured kidney, highlighting the regulatory roles of both DCs and Rictor in the pathophysiology of acute kidney injury.

Innate and adaptive immune responses subsequent to ischemia-reperfusion injury in the kidney

Understanding innate immune responses and their correlation to alloimmunity after solid organ transplantation is key to optimizing long term graft outcome. While Ischemia/Reperfusion injury (IRI) has been well studied, new insight into central mechanisms of innate immune activation, i.e. chemokine mediated cell trafficking and the role of Toll-like receptors have evolved recently. The mechanistic implications of Neutrophils, Macrophages/Monocytes, NK-cells, Dendritic cells in renal IRI has been proven by selective depletion of these cell types, thereby offering novel therapeutic interventions. At the same time, the multi-faceted role of different T-cell subsets in IRI has gained interest, highlighting the dichotomous effects of differentiated T-cells and suggesting more selective therapeutic approaches. Targeting innate immune cells and their activation and migration pathways, respectively, has been promising in experimental models holding translational potential. This review will summarize the effects of innate immune activation and potential strategies to interfere with the immunological cascade following renal IRI.

CD39 expression by hepatic myeloid dendritic cells attenuates inflammation in liver transplant ischemia-reperfusion injury in mice

Hepatic innate immune cells, in particular, interstitial dendritic cells (DCs), regulate inflammatory responses and may promote inherent liver tolerogenicity. After tissue injury, adenosine triphosphate (ATP) is released and acts as a damage-associated molecular pattern that activates innate immune cells by pattern recognition receptors. CD39 (ectonucleoside triphosphate diphosphohydrolase-1) rapidly hydrolyzes extracellular ATP to maintain physiological levels. We hypothesized that CD39 expression on liver DCs might contribute to regulation of their innate immune functions. Mouse liver conventional myeloid DCs (mDCs) were hyporesponsive to ATP, compared with their splenic counterparts. This disparity was ascribed to more efficient hydrolysis of ATP by higher expression of CD39 on liver mDCs. Human liver mDCs expressed greater levels of CD39 than those from peripheral blood. The comparatively high expression of CD39 on liver mDCs correlated strongly with both ATP hydrolysis and adenosine production. Notably, CD39(-/-) mouse liver mDCs exhibited a more mature phenotype, greater responsiveness to Toll-like receptor 4 ligation, and stronger proinflammatory and immunostimulatory activity than wild-type (WT) liver mDCs. To investigate the role of CD39 on liver mDCs in vivo, we performed orthotopic liver transplantation with extended cold preservation using CD39(-/-) or WT donor mouse livers. Compared to WT liver grafts, CD39(-/-) grafts exhibited enhanced interstitial DC activation, elevated proinflammatory cytokine levels, and more-severe tissue injury. Moreover, portal venous delivery of WT, but not CD39(-/-) liver mDCs, to donor livers immediately post-transplant exerted a protective effect against graft injury in CD39(-/-) to CD39(-/-) liver transplantation.

CONCLUSIONS

These data reveal that CD39 expression on conventional liver mDCs limits their proinflammatory activity and confers protective properties on these important innate immune cells against liver transplant ischemia/reperfusion injury.

Effect of ischemia preconditioning on renal ischemia/reperfusion injury in rats

OBJECTIVE

To study the effect of ischemia preconditioning (IP) on renal ischemia/reperfusion (I/R)-associated functional injury and expression of renal adhesion molecules in rats.

MATERIALS AND METHODS

The ischemia preconditioning plan adopted in this experiment involved renal warm ischemia for 6 min. and blood flow for 4 min., repeated four times. The Wistar rat kidneys used for warm ischemia preconditioning were subjected to 60 min of renal warm ischemia followed by reperfusion. The rat kidneys with ischemia/reperfusion were compared with the ischemia preconditioning group to observe rat renal function and changes in the expression of renal adhesion molecules ICAM-1, P-Selectin, and E-Selectin.

RESULTS

The expression of rat renal adhesion molecules (ICAM-1, P-Selectin, and E-Selectin) with ischemia preconditioning was significantly lower than that of the ischemia/reperfusion group. Serum creatinine was significantly lower than that in the ischemia/reperfusion group after 48 hours.

CONCLUSIONS

Ischemia preconditioning has a protective effect on renal function. Reduced expression of renal adhesion molecules is likely a mechanism involved in the observed protection.

Monoclonal antibody to intercellular adhesion molecule-1 as a novel therapy for preeclampsia: preliminary results from a rat model

OBJECTIVE

Preeclampsia is a prevalent and potentially devastating complication of pregnancy. Intercellular adhesion molecule-1 (ICAM-1) was reported to be involved in the pathogenesis of the disease. Therefore we hypothesized anti-ICAM-1 monoclonal antibody (mAb) could be a therapeutic choice for preeclampsia. The objective of this study was to evaluate its therapeutic effects using a rat model of preeclampsia.

METHODS

Timed pregnant Wistar rats were intravenously injected endotoxin and then randomized to receive either anti-ICAM-1 mAb or saline. The effects of antibody on blood pressure, urinary protein, levels of alanine aminotransferase (ALT), blood urea nitrogen (BUN), creatinine, uric acid, weight of placenta were measured. Pregnancy outcomes were evaluated.

RESULTS

Anti-ICAM-1 mAb significantly decreased the levels of blood pressure, urinary protein, maternal BUN, creatnine and uric acid comparing with untreated preeclamptic rats. And the antibody therapy significantly improved pregnancy outcomes. After five days of mAb treatment, most of the parameters in mAb-treated group approached normal levels.

CONCLUSIONS

Our data prove anti-ICAM-1 mAb therapy as a promising choice for preeclampsia.

Immunopathogenesis of ischemia/reperfusion-associated tissue damage

Ischemia/reperfusion (IR) instigates a complex array of inflammatory events which result in damage to the local tissue. IR-related organ damage occurs invariably in several clinical conditions including trauma, organ transplantation, autoimmune diseases and revascularization procedures. We critically review available pre-clinical experimental information on the role of immune response in the expression of tissue damage following IR. Distinct elements of the innate and adaptive immune response are involved in the expression of tissue injury. Interventions such as prevention of binding of natural antibody to antigen expressed on the surface of ischemia-conditioned cells, inhibition of the ensuing complement activation, modulation of Toll-like receptors, B or T cell depletion and blockade of inflammatory cytokines and chemokines limit IR injury in preclinical studies. Clinical trials that will determine the therapeutic value of each approach is needed.

Anti-inflammatory treatment strategies for ischemia/reperfusion injury in transplantation

Inflammatory reactions in the graft have a pivotal influence on acute as well as long-term graft function. The main reasons for an inflammatory reaction of the graft tissue are rejection episodes, infections as well as ischemia/reperfusion (I/R) injury. The latter is of particular interest as it affects every solid organ during the process of transplantation. I/R injury impairs acute as well as long-term graft function and is associated with an increased number of acute rejection episodes that again affect long-term graft outcome.

I/R injury is the result of ATP depletion during prolonged hypoxia. Further tissue damage results from the reperfusion of the tissue after the ischemic insult. Adaptive cellular responses activate the innate immune system with its Toll-like receptors and the complement system as well as the adaptive immune system. This results in a profound inflammatory tissue reaction with immune cells infiltrating the tissue. The damage is mediated by various cytokines, chemokines, adhesion molecules, and compounds of the extracellular matrix. The expression of these factors is regulated by specific transcription factors with NF-κB being one of the key modulators of inflammation.

Strategies to prevent or treat I/R injury include blockade of cytokines/chemokines, adhesion molecules, NF-κB, specific MAP kinases, metalloproteinases, induction of protective genes, and modulation of the innate immune system. Furthermore, preconditioning of the donor is an area of intense research. Here pharmacological treatment as well as new additives to conventional cold storage solutions have been analyzed together with new techniques for the perfusion of grafts, or methods of normothermic storage that would avoid the problem of cold damage and graft ischemia.

However, the number of clinical trials in the field of I/R injury is limited as compared to the large body of experimental knowledge that accumulated during recent years in the field of I/R injury. Future activities in the treatment of I/R injury should focus on the translation of experimental protocols into clinical trials in order to reduce I/R injury and, thus, improve short- as well as long-term graft outcome.

Reoxygenation of hypoxia-differentiated dentritic cells induces Th1 and Th17 cell differentiation

Dendritic cells (DCs) are often exposed to various oxygen tensions under physiological and pathological conditions. However, the effects of various oxygen tensions on DC functions remain unclear. In this study, we showed that hypoxia-differentiated DCs expressed lower levels of MHC-II molecule, co-stimulatory molecules (CD80, CD86) and proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), but higher levels of immunoregulatory cytokine transforming growth factor-beta (TGF-beta) than normoxia-differentiated DCs. Unexpectedly, re-exposure of hypoxia-differentiated DCs to saturated oxygen (reoxygenation) completely restored their mature phenotype and function. Specifically, the reoxygenated DCs induced naïve CD4(+) T cells to differentiate into Th1 and Th17 effector cells, but deceased the generation of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs). The data indicate that hypoxic microenvironment suppresses the maturation and function of murine DCs. Reoxygenation of hypoxia-differentiated DCs however results in complete recovery of their mature phenotype and function, and has strong ability to drive immune response toward a proinflammatory direction, suggesting reoxygenated DCs may contribute to inflammation of ischemia-reperfusion injury.

Ischemia-reperfusion and immediate T cell responses

The pathogenesis of ischemia-reperfusion injury (IRI) is complex and not well understood. Inflammation plays an important role in IRI, with involvement of leukocytes, adhesion molecules, chemokines and cytokines. Emerging data suggest a role of T cells as mediators of IRI both in renal and extra-renal organs. Divergent roles of T cell subsets have also been elucidated, suggesting a more complicated role of T cells in the different phases of IRI. This review presents recent evidence from various animal models that advances our understanding of the role T cells play in IRI. These findings entertain the possibility of using immunotherapeutic agents for the prevention and treatment of IRI.

Effects of Huoxue Huayu injection I pretreatment and ischemic preconditioning on liver ischemia and reperfusion injury in rats

AIM: To investigate the effects of Huoxue Huayu injection I (HHI-I) pretreatment and ischemic preconditioning (IP) on hepatic ischemia and reperfusion (I/R) injury in rats and compare their efficacity.

METHODS: Eighty healthy adult male Sprague-Dawley rats were randomly and averagely divided into 4 groups: sham operation (SO) group, I/R group, ischemia preconditioning (IP) group, and HHI-I pretreatment group. After partial hepatic I/R model was made, the rats of each group were sacrificed to determine serum alanine aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), tissue malondialdehyde (MDA) and superoxide dismutase (SOD) level 1、3、6、24 h after reperfusion, respectively. Tissue tumor necrosis factor alpha (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) mRNA levels were determined by reverse transcription-polymerase chain reaction after 1 h of reperfusion. Liver histology was observed after 3 h of reperfusion.

RESULTS: The activities of ALT, AST, LDH, the level of MDA, and the expression of TNF-α, ICAM-1 mRNA in I/R, IP, and HHI-I group were significantly higher than those in SO group, but they were markedly lower in IP and HHI-I group than those in I/R group. The activities of ALT, AST, LDH in HHI-I group were significantly lower than those in IP group (ALT: 2378.8 ± 303.4 nkat/L vs 2840.6 ± 248.4 nkat/L; AST: 2887.2 ± 270.1 nkat/L vs 4567.6 ± 275.1 nkat/L; LDH: 10550.4 ± 710.1 nkat/L vs 12164.1 ± 735.1 nkat/L; all P < 0.05). As compared with that in the IP group, the level of MDA in HHI-I group was decreased at the 3^rd and 6^th hour (17.35 ± 1.39 nmol/g vs 21.66 ± 1.84 nmol/g, P < 0.05), and the mRNA expression of TNF-α and ICAM-1 were decreased (TNF-α: 0.54 ± 0.06 vs 0.78 ± 0.08; ICAM-1: 0.43 ± 0.03 vs 0.69 ± 0.11, both P < 0.01). The level of SOD in I/R, IP and HHI-I group was markedly lower than that in SO group (P < 0.05), but it was significantly higher in IP and HHI-I group than that in I/R group (P < 0.05). The SOD level in the animals received HHI-I was significantly increased in comparison with that in IP group (136.00 ± 12.50 nmol/g vs 124.70 ± 9.32 nmol/g, P < 0.05). Microscopy showed that liver injury in the HHI-I-treated animals and IP-treated animals were attenuated as compared with that in I/R group.

CONCLUSION: HHI-I and IP pretreatment can alleviate I/R-induced liver injury, and the former is superior to the latter. The protective mechanism of HHI-I may be associated with the improvement of liver microcirculation, elimination of tissue anoxia, transcription inhibition of cytokine and cell adhesion molecule such as TNF-α and ICAM-1, and decrease of neutrophil infiltration.

Molecular characterization of rat leukocyte P-selectin glycoprotein ligand-1 and effect of its blockade: protection from ischemia-reperfusion injury in liver transplantation

P-selectin glycoprotein ligand-1 (PSGL-1) mediates the initial tethering of leukocytes to activated platelets and endothelium. We report molecular cloning and characterization of the rat PSGL-1 gene. A neutralizing Ab was generated, and its binding epitope was mapped to the N-terminal binding region of rat PSGL-1. We examined the effects of early PSGL-1 blockade in rat liver models of cold ischemia, followed by ex vivo reperfusion or transplantation (orthotopic liver transplantation (OLT)) using an anti-PSGL-1 Ab with diminished Fc-mediated effector function. In the ex vivo hepatic cold ischemia and reperfusion model, pretreatment with anti-PSGL-1 Ab improved portal venous flow, increased bile production, and decreased hepatocellular damage. Rat pretreatment with anti-PSGL-1 Ab prevented hepatic insult in a model of cold ischemia, followed by OLT, as assessed by 1) decreased hepatocellular damage (serum glutamic oxaloacetic transaminase/glutamic-pyruvic transaminase levels), and ameliorated histological features of ischemia/reperfusion injury, consistent with extended OLT survival; 2) reduced intrahepatic leukocyte infiltration, as evidenced by decreased expression of P-selectin, ED-1, CD3, and OX-62 cells; 3) inhibited expression of proinflammatory cytokine genes (TNF-alpha, IL-1beta, IL-6, IFN-gamma, and IL-2); and 4) prevented hepatic apoptosis accompanied by up-regulation of antiapoptotic Bcl-2/Bcl-xL protective genes. Thus, targeting PSGL-1 with a blocking Ab that has diminished Fc-mediated effector function is a simple and effective strategy that provides the rationale for novel therapeutic approaches to maximize the organ donor pool through the safer use of liver transplants despite prolonged periods of cold ischemia.

Inhibition of P-selectin L-EGF monoclonal antibody on metastasis of human gastric carcinoma in severe combined immunodeficient mice

AIM: To investigate the role of cell adhesion molecule P-selectin L-EGF monoclonal antibody (L-EGF Mab) in the inhibition of the metastasis of gastric cancer in sev-ere combined immunodeficient (SCID) mice.

METHODS: Human gastric cancer cell line SGC-7901 was orthotopically implanted into SCID mice to estab-lish metastatic model. At the 3^rd day after implantation, the mice were intravenously injected with normal saline (n = 11) or P-selectin L-EGF Mab (n = 9). At the end of the 6^th wk, pathological examinations were performed on the tissues from stomach and other possible invad-ed organs. Meanwhile, polymerase chain reaction was performed on the gastric cancer tissues.

RESULTS: The metastatic rate in the mice treated with normal saline was 81.8% (9/11), and that in the mice treated with P-selectin L-EGF Mab was 11.1% (1/9). There was significant difference between them (P <0.05). The level of P-selectin mRNA expression in the gastric can-cer with metastasis was markedly increased in com-parison with that without metastasis, and P-selectin mRNA expression in the mice treated with P-selectin L-EGF Mab was significantly lower than that in the ones treated with normal saline (cycle threshold: 20.54±2.20 vs 17.09±1.40, P <0.05).

CONCLUSION: CONCLUSION: P-selectin adhesion molecule is related to tumor metastasis, and P-selectin L-EGF Mab can inhibit the metastasis by down-regulating the express-ion of P-selectin mRNA..

Modulation of monocyte-derived dendritic cell differentiation is associated with ischemic acute renal failure

BACKGROUND

Dendritic cells (DCs) play a central role in both stimulating and suppressing immune responses and are impacted by surgical injury, exercise, and other physiological stressors. This study aims to determine whether renal ischemia/reperfusion (I/R) injury alters the differentiation, maturation, and activation of DCs from peripheral blood monocytes (PBMo).

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were subjected to I/R injury or sham-operated. Creatinine clearance (CCr) was monitored daily during the 14 days of reperfusion that followed the ischemic insult. At 2 and 14 days of reperfusion, the following properties of PBMo derived-DCs were assessed: the amount of generated DCs, surface markers [CD11c, CD80, CD86, and MHC-II (IA)], and functional status including magnitude of mixed lymphocyte reaction (MLR), production of IL-12 p70 by DCs, and production of IFN-gamma and IL-4 by DC-stimulated T cells.

RESULTS

CCr was greatly reduced in the injured rats 0 to 4 days after ischemia. Two days after I/R injury to kidney, the numbers of DCs differentiated from PBMo, IL-12 production by DCs, expression of MHC-II (IA), and IFN-gamma production by DC-stimulated T cells were significantly increased in the I/R injured group (compared to the sham-operated group). After 14 days of reperfusion, there was no between-group differences in the numbers of DCs derived from PBMo, MLR, expression of CD80, CD86, and MHC-II (IA), and production of IL-12, IFN-gamma, and IL-4.

CONCLUSIONS

The increases seen at 2 days of reperfusion may reflect a preparatory step in the renal I/R injury pathway. The relationship between up-regulation of DC differentiation and ischemic acute renal failure (ARF) remains to be elucidated.