Tissue-Type Plasminogen Activator Modulates Inflammatory Responses and Renal Function in Ischemia Reperfusion Injury

Abstract

Acute renal failure is often the result of ischemia-reperfusion (I/R) injury. Neutrophil influx is an important damaging event in I/R. Tissue-type plasminogen activator (tPA) not only is a major fibrinolytic agent but also is involved in inflammatory processes. A distinct upregulation of tPA after I/R, with de novo tPA production by proximal renal tubules, was found. For investigating the role of tPA in I/R, renal ischemia was induced in tPA؊/؊ and wild-type (WT) mice by clamping both renal arteries for 35 min followed by reperfusion. Mice were killed 1, 5, and 10 d after reperfusion. After 1 d, tPA؊/؊ mice displayed significantly less neutrophil influx into the interstitial area compared with WT mice. In addition, tPA؊/؊ mice showed quicker recovery of renal function than WT mice. The protocol was repeated after injection of tPA-antisense oligonucleotides into WT mice, leading to even more explicit results: Antisense-treated mice showed less histologic damage, better renal function, and less neutrophil influx than control mice. Surprising, complement C3 concentration, levels of proinflammatory cytokines and chemokines, intercellular adhesion molecule-1 expression, and matrix metalloproteinase activity were similar in WT and tPA؊/؊ mice. Plasmin activity levels in WT and tPA؊/؊ kidneys were also comparable, indicating that tPA influences neutrophil influx into ischemic renal tissue independent from plasmin generation. This study shows that targeting tPA could be of therapeutic importance in treating I/R injury by diminishing neutrophil influx and preserving renal function.

Thrombin-dependent intravascular leukocyte trafficking regulated by fibrin and the platelet receptors GPIb and PAR4

“…In addition, rt-PA has been shown to increase tissue injury and enhance neutrophil tissue infiltration following ischaemiareperfusion injury to the brain 60 , lung 61 and kidneys 62 . The known proinflammatory function of recombinant t-PA has been partly attributed to its direct activating effects on the endothelium and inflammatory cells, as well as through the generation of fibrin degradation products 63 and plasmin 64 .…”

RAGE Does Not Contribute to Renal Injury and Damage upon Ischemia/Reperfusion-Induced Injury

“…The degree of necrosis was scored by a pathologist in a blinded fashion on a 5-point scale: 0 = no damage, 1 = 10% necrosis of the corticomedullary junction, 2 = 10-25%, 3 = 25-50%, 4 = 50-75%, 5 = more than 75%. For immunostaining, 4-m tissue sections were incubated with specific antibodies for granulocytes (FITC-labeled anti-mouse Ly6G mAb; BD Biosciences-Pharmingen), apoptosis (rabbit anti-human active caspase-3; Cell Signaling Technology), GFP (rabbitanti GFP IgG; Molecular Probes), HMGB1 (rabbit-anti mouse HMGB1; Abcam), S100B (rabbit anti-S100B; Sigma-Aldrich) or CML ( N -epsilon carboxymethyl lysine) which has been identified as a major structure in advanced glycation end-products (AGE), mouse IgG, Biologo) followed by appropriate secondary antibodies as described before [15,16,[20][21][22][23]. To determine percentage of positive staining on kidney tissue slides, approximately 10 pictures of tissue section were taken under light microscopy (magnification !…”

Neutrophils infiltration is early event of an oral mucosal xenotransplantation model

“…(3) ELISA analysis of MPO: The concentration of MPO in supernatants was determined using an ELISA kit (HyCult Bio-technology, Uden, Netherlands) as previously described (20). The concentration of MPO in tissue was expressed as the ratio of MPO concentration to total protein in order to take into account slight differences of tissue weights (21).…”