Pentraxin-3-mediated complement activation in a swine model of renal ischemia/reperfusion injury.
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ABSTRACT:
SUBMITTER: Divella C
PROVIDER: S-EPMC8109140 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background: Ischemia reperfusion injury (IRI) plays a major role in solid organ transplantation. The length of warm ischemia time is critical for the extent of tissue damage in renal IRI. In this experimental study we hypothesized that local release of labile heme in renal tissue is triggered by the duration of warm ischemia (15 vs. 45 min IRI) and mediates complement activation, cytokine release, and inflammation. Methods: To induce IRI, renal pedicle clamping was performed in male C57BL/6 mice for short (15 min) or prolonged (45 min) time periods. Two and 24 h after experimental ischemia tissue injury labile heme levels in the kidney were determined with an apo-horseradish peroxidase assay. Moreover, renal injury, cytokines, and C5a and C3a receptor (C5aR, C3aR) expression were determined by histology, immunohistochemistry and qPCR, respectively. In addition, in vitro studies stimulating bone marrow-derived macrophages with LPS and the combination of LPS and heme were performed and cytokine expression was measured. Results: Inflammation and local tissue injury correlated with the duration of warm ischemia time. Labile heme concentrations in renal tissue were significantly higher after prolonged (45 min) as compared to short (15 min) IRI. Notably, expression of the inducible heme-degrading enzyme heme oxygenase-1 (HO-1) was up-regulated in kidneys after prolonged, but not after short IRI. C5aR, the pro-inflammatory cytokines IL-6 and TNF-α as well as pERK were up-regulated after prolonged, but not after short ischemia times. Consecutively, neutrophil infiltration and up-regulation of pro-fibrotic cytokines such as CTGF and PAI were more pronounced in prolonged IRI in comparison to short IRI. In vitro stimulation of macrophages with LPS revealed that IL-6 expression was enhanced in the presence of heme. Finally, administration of the heme scavenger human serum albumin (HSA) reduced the expression of pro-inflammatory cytokines, C3a receptor and improved tubular function indicated by enhanced alpha 1 microglobulin (A1M) absorption after IRI. Conclusions: Our data show that prolonged duration of warm ischemia time increased labile heme levels in the kidney, which correlates with IRI-dependent inflammation and up-regulation of anaphylatoxin receptor expression.
| S-EPMC6933315 | biostudies-literature
Project description:Complement activation is involved in the pathogenesis of ischemia reperfusion injury (IRI), which is an inevitable process during kidney transplantation. Therefore, complement-targeted therapeutics hold great potential in protecting the allografts from IRI. We observed universal deposition of C3d and membrane attack complex in human renal allografts with delayed graft function or biopsy-proved rejection, which confirmed the involvement of complement in IRI. Using FB-, C3-, C4-, C5-, C5aR1-, C5aR2-, and C6-deficient mice, we found that all components, except C5aR2 deficiency, significantly alleviated renal IRI to varying degrees. These gene deficiencies reduced local (deposition of C3d and membrane attack complex) and systemic (serum levels of C3a and C5a) complement activation, attenuated pathological damage, suppressed apoptosis, and restored the levels of multiple local cytokines (e.g., reduced IL-1β, IL-9, and IL-12p40 and increased IL-4, IL-5, IL-10, and IL-13) in various gene-deficient mice, which resulted in the eventual recovery of renal function. In addition, we demonstrated that CRIg/FH, which is a targeted complement inhibitor for the classical and primarily alternative pathways, exerted a robust renoprotective effect that was comparable to gene deficiency using similar mechanisms. Further, we revealed that PI3K/AKT activation, predominantly in glomeruli that was remarkably inhibited by IRI, played an essential role in the CRIg/FH renoprotective effect. The specific PI3K antagonist duvelisib almost completely abrogated AKT phosphorylation, thus abolishing the renoprotective role of CRIg/FH. Our findings suggested that complement activation at multiple stages induced renal IRI, and CRIg/FH and/or PI3K/AKT agonists may hold the potential in ameliorating renal IRI.
| S-EPMC6287101 | biostudies-literature
Project description:Inflammation is a major contributor to the pathogenesis of ischemic acute kidney injury (AKI), which complicates the post-operative outcomes of large numbers of hospitalized surgical patients. Hydroxychloroquine (HCQ), a well-known anti-malarial drug, is commonly used in clinical practice for its anti-inflammatory actions. However, little is known about its role in renal ischemia/reperfusion (I/R) injury. In the current study, mice were subjected to I/R injury and HCQ was administered for seven days by gavage prior to surgery. In parallel, HK-2 human renal proximal tubule cells were prophylactically treated with HCQ and then were exposed to hypoxia/reoxygenation (H/R). The results showed that HCQ significantly attenuated renal dysfunction evidenced by blunted decreases in serum creatinine and kidney injury molecular-1 expression and the improvement of HK-2 cell viability. Additionally, HCQ markedly reduced macrophage and neutrophil infiltration, pro-inflammatory cytokine production, and NLRP3 inflammasome activation. Mechanistic studies showed that HCQ could inhibit the priming of the NLRP3 inflammasome by down-regulating I/R or H/R-induced NF-?B signaling. Moreover, HCQ reduced cathepsin (CTS) B, CTSD and CTSL activity, and their redistribution from lysosomes to cytoplasm. CTSB and CTSL (not CTSD) were implicated in I/R triggered NLRP3 inflammasome activation. Notably, we found that HCQ attenuated renal injury through downregulation of CTSB and CTSL-mediated NLRP3 inflammasome activation. This study provides new insights into the anti-inflammatory effect of HCQ in the treatment of AKI.
| S-EPMC5834539 | biostudies-literature
Project description:Background and objectivesThe complement cascade seems to be an important mediator modulating renal ischemia/reperfusion injury. This study analyzed whether significant changes occur in the levels of a terminal panel of complement molecules (C3a, C5a, and C5b-9/membrane attack complex) during the early phase of human kidney allograft reperfusion and evaluated the potential association of these changes with clinical post-transplant graft function in kidney transplant recipients.Design, setting, participants, & measurementsSeventy-five renal transplant recipients undergoing transplantation between 2004 and 2006 were enrolled in the study and divided into early, slow, and delayed graft function groups. Blood samples were collected perioperatively during consecutive minutes of allograft reperfusion from the renal vein. Levels of complement molecules were measured using ELISA.ResultsAnalysis revealed no significant changes in C3a and C5a levels throughout reperfusion. The main complement molecule that was significantly associated with post-transplant graft function was C5b-9/membrane attack complex; throughout the reperfusion period, perioperative levels of C5b-9/membrane attack complex were around two to three times higher in delayed graft function patients than early and slow graft function individuals (P<0.005). In addition, C5b-9/membrane attack complex levels had a relatively high clinical sensitivity and specificity (70%-87.5%) for the prediction of early and long-term (1 year) post-transplant allograft function.ConclusionsThis clinical study supports a role for the complement cascade in delayed graft function development. However, additional studies are needed to elucidate the exact mechanisms responsible for this phenomenon. In addition, perioperative measurements of C5b-9/membrane attack complex are highlighted as promising potential clinical markers of post-transplant renal allograft function.
| S-EPMC3488944 | biostudies-literature
Project description:ischemia-reperfusion injury (IRI) after hemorrhage is potentiated by aortic occlusion or resuscitative endovascular balloon occlusion of the aorta (REBOA). Given the central role of mitochondrial injury in shock, we hypothesized that Elamipretide, a peptide that protects mitochondria, would mitigate IRI after hemorrhagic shock and REBOA. Twelve pigs were subjected to hemorrhagic shock and 45 min of REBOA. After 25 min of REBOA, animals received either saline or Elamipretide. Animals were transfused with autologous blood during balloon deflation, and pigs were resuscitated with isotonic crystalloids and norepinephrine for 4.25 h. Elamipretide-treated animals required less crystalloids than the controls (62.5 [50-90] and 25 [5-30] mL/kg, respectively), but similar amounts of norepinephrine (24.7 [8.6-39.3] and 9.7 [2.1-12.5] mcg/kg, respectively). Treatment animals had a significant reduction in serum creatinine (control: 2.7 [2.6-2.8]; Elamipretide: 2.4 [2.4-2.5] mg/dL; p = 0.04), troponin (control: 3.20 [2.14-5.47] ng/mL, Elamipretide: 0.22 [0.1-1.91] ng/mL; p = 0.03), and interleukin-6 concentrations at the end of the study. There were no differences in final plasma lactate concentration. Elamipretide reduced fluid requirements and protected the kidney and heart after profound IRI. Further understanding the subcellular consequences of REBOA and mitochondrial rescue will open new therapeutic avenues for patients suffering from IRI after hemorrhage.
| S-EPMC10024723 | biostudies-literature
Project description:After kidney ischemia/reperfusion (I/R) injury, monocytes home to the kidney and differentiate into activated macrophages. Whereas proinflammatory macrophages contribute to the initial kidney damage, an alternatively activated phenotype can promote normal renal repair. The microenvironment of the kidney during the repair phase mediates the transition of macrophage activation from a proinflammatory to a reparative phenotype. In this study, we show that macrophages isolated from murine kidneys during the tubular repair phase after I/R exhibit an alternative activation gene profile that differs from the canonical alternative activation induced by IL-4-stimulated STAT6 signaling. This unique activation profile can be reproduced in vitro by stimulation of bone marrow-derived macrophages with conditioned media from serum-starved mouse proximal tubule cells. Secreted tubular factors were found to activate macrophage STAT3 and STAT5 but not STAT6, leading to induction of the unique alternative activation pattern. Using STAT3-deficient bone marrow-derived macrophages and pharmacologic inhibition of STAT5, we found that tubular cell-mediated macrophage alternative activation is regulated by STAT5 activation. Both in vitro and after renal I/R, tubular cells expressed GM-CSF, a known STAT5 activator, and this pathway was required for in vitro alternative activation of macrophages by tubular cells. Furthermore, administration of a neutralizing antibody against GM-CSF after renal I/R attenuated kidney macrophage alternative activation and suppressed tubular proliferation. Taken together, these data show that tubular cells can instruct macrophage activation by secreting GM-CSF, leading to a unique macrophage reparative phenotype that supports tubular proliferation after sterile ischemic injury.
| S-EPMC4446881 | biostudies-literature
Project description:The complement system is a major component of innate immunity and has been commonly identified as a central element in host defense, clearance of immune complexes, and tissue homeostasis. After ischemia-reperfusion injury (IRI), the complement system is activated by endogenous ligands that trigger proteolytic cleavage of complement components via the classical, lectin and/or alternative pathway. The result is the formation of terminal complement components C3a, C5a, and the membrane attack complex (C5b-9 or MAC), all of which play pivotal roles in the amplification of the inflammatory response, chemotaxis, neutrophil/monocyte recruitment and activation, and direct tubular cell injury. However, recent evidence suggests that complement activity transcends innate host defense and there is increasing data suggesting complement as a regulator in processes such as allo-immunity, stem cell differentiation, tissue repair, and progression to fibrosis. In this review, we discuss recent advances addressing the role of complement as a regulator of IRI and renal fibrosis after organ donation for transplantation. We will also briefly discuss currently approved therapies that target complement activity in kidney ischemia-reperfusion and transplantation.
| S-EPMC4224961 | biostudies-literature
Project description:Renal ischemia-reperfusion injury (IRI) is mainly responsible for acute kidney injury for which there is no effective therapy. Accumulating evidence has indicated the important role of mitophagy in mitochondrial homeostasis under stress. OGG1 (8-oxoguanine DNA glycosylase) is known for functions in excision repair of nuclear and mitochondrial DNA. However, the role of OGG1 in renal IRI remains unclear. Herein, we identified OGG1, induced during IRI, as a key factor mediating hypoxia-reoxygenation-induced apoptosis in vitro and renal tissue damage in a renal IRI model. We demonstrated that OGG1 expression during IRI negatively regulates mitophagy by suppressing the PINK1/Parkin pathway, thereby aggravating renal ischemic injury. OGG1 knockout and pharmacological inhibition attenuated renal IRI, in part by activating mitophagy. Our results elucidated the damaging role of OGG1 activation in renal IRI, which is associated with the regulatory role of the PINK1/Parkin pathway in mitophagy.
| S-EPMC10392062 | biostudies-literature
Project description:ERK5, a member of the mitogen activated protein kinase, expressed in the kidneys was smaller (∼80kDa) in apparent molecular mass compared to other organs (∼120kDa). A blocking peptide experiment confirmed that the ∼80kDa detected on Western blots was a specific band detected by the anti-ERK5 antibody. Expression of the known ERK5 variants ERK5a, b, c, and T confirmed that none of the known splice variants encoded for the renal-specific ∼80kDa protein. However, RT-PCR with primers targeting the potential splice sites did not reveal a novel transcript in the kidney. The smaller molecular mass of the kidney-specific ERK5-immunoreactive protein suggested that this cyto-protective molecule may not be fully functional in the kidneys. Lentivirus-mediated in vivo overexpression of full length ERK5 in the mouse kidneys provided protection against renal IR injury. The identity of the renal-specific ∼80kDa ERK5 remains unknown but a better understanding of the ERK5 expression and post-translational processing in the kidneys may reveal a novel strategy for renal protection.
| S-EPMC3288778 | biostudies-literature
Project description:Chronic kidney disease (CKD), which is associated with high morbidity, remains a worldwide health concern, while effective therapies remain limited. Hydroxychloroquine (HCQ), which mainly targets toll-like receptor-7 (TLR-7) and TLR-9, is associated with a lower risk of incident CKD. Taking into account that TLR-9 is involved in the development of renal fibrosis and serves as a potential therapy target for CKD, we investigated whether HCQ could attenuate CKD via TLR-9 signal pathway. The effects of HCQ on renal tubulointerstitial fibrosis were further explored using a mouse model of renal tubulointerstitial fibrosis after ischemia/reperfusion injury. Bone marrow-derived macrophages were isolated to explore the effects of HCQ in vitro. Judicious use of HCQ efficiently inhibited the activation of macrophages and MAPK signaling pathways, thereby attenuating renal fibrosis in vivo. In an in vitro model, results showed that HCQ promoted apoptosis of macrophages and inhibited activation of macrophages, especially M2 macrophages, in a dose-dependent manner. Because TLR-7 is not involved in the development of CKD post-injury, a TLR-9 knockout mouse was used to explore the mechanisms of HCQ. The effects of HCQ on renal fibrosis and macrophages decreased after depletion of TLR-9 in vivo and in vitro. Taken together, this study indicated that proper use of HCQ could be a new strategy for anti-fibrotic therapy and that TLR-9 could be a potential therapeutic target for CKD following acute kidney injury.
| S-EPMC8079743 | biostudies-literature