Alkaline phosphatase treatment of acute kidney injury - an update.

Through improved insight in the increasing incidence and detrimental effects of acute kidney injury (AKI), its clinical relevance has become more and more apparent. Although treatment strategies for AKI have also somewhat improved, an adequate remedy still does not exist. Finding one is complicated by a multifactorial pathophysiology and by heterogeneity in the patient population. Alkaline phosphatase (AP) has been suggested as a therapy for sepsis-associated AKI because of its protective effects against lipopolysaccharide (LPS) induced inflammation and kidney injury in animals. However, translation of these protective effects into tangible clinical benefit has proven difficult. Because the anti-inflammatory properties of AP are likely not reliant on a direct effect on LPS itself, we postulate that other pathways are much more important in explaining the renoprotective properties ascribed to AP. The reevaluation of which properties of the AP enzyme are responsible for the benefit seen in the lab, is an important step to determine where the true potential of AP as a treatment strategy for AKI in the clinic lies. In this review, we will discuss how AP can prevent activation of harmful pro-inflammatory receptors, redirect cell-cell signaling, and protect barrier tissues, which together form the basis for current knowledge of the role of AP in the kidney. With this knowledge in mind and by analyzing currently available clinical evidence, we propose directions for new research that can determine whether AP as a treatment strategy for AKI has a future in the clinical field.

Male versus female inflammatory response after brain death model followed by ex vivo lung perfusion.

BACKGROUND: Ex vivo lung perfusion (EVLP) is a useful tool for assessing lung grafts quality before transplantation. Studies indicate that donor sex is as an important factor for transplant outcome, as females present higher inflammatory response to brain death (BD) than males. Here, we investigated sex differences in the lungs of rats subjected to BD followed by EVLP. METHODS: Male and female Wistar rats were subjected to BD, and as controls sham animals. Arterial blood was sampled for gas analysis. Heart-lung blocks were kept in cold storage (1 h) and normothermic EVLP carried out (4 h), meanwhile ventilation parameters were recorded. Perfusate was sampled for gas analysis and IL-1ß levels. Leukocyte infiltration, myeloperoxidase presence, IL-1ß gene expression, and long-term release in lung culture (explant) were evaluated. RESULTS: Brain dead females presented a low lung function after BD, compared to BD-males; however, at the end of the EVLP period oxygenation capacity decreased in all BD groups. Overall, ventilation parameters were maintained in all groups. After EVLP lung infiltrate was higher in brain dead females, with higher neutrophil content, and accompanied by high IL-1ß levels, with increased gene expression and concentration in the culture medium (explant) 24 h after EVLP. Female rats presented higher lung inflammation after BD than male rats. Despite maintaining lung function and ventilation mechanics parameters for 4 h, EVLP was not able to alter this profile. CONCLUSION: In this context, further studies should focus on therapeutic measures to control inflammation in donor or during EVLP to increase lung quality.

As there is a shortage of viable lungs for transplantation, methods of lung preservation, such as ex vivo perfusion, are important. This method is a good alternative, as it will not only preserve the lungs, but also enable lung function assessment and treatment of the organs. Studies have showed that lungs from donors of the female sex have greater risk of being rejected, when transplanted to male receptors. However, it's not certain if sex differences in anatomy, physiology and specially in immune response could interfere with the transplant result. Females do present a greater and more efficient immune response to any hazard, however after brain death this control is lost, producing a great inflammatory response as a result. Therefore, in this study we have investigated in more detail the influence of sex on the effects of brain death followed by the preservation method. Thus, we performed a brain death model in males and females rats and placed their lungs in an ex vivo lung perfusion machine. At the end of the experiment, we analyzed lung ventilation, gas exchange, and inflammatory parameters. The obtained data indicated that overall the lung ventilation and gas exchange is maintained by the ex vivo perfusion machine. Also, that lung inflammation is influenced by the sex of the donor; where the lungs from females present greater inflammation compared to the lungs from males.

Comparison of acute kidney injury following brain death between male and female rats.

BACKGROUND: Clinical reports associate kidneys from female donors with worse prognostic in male recipients. Brain Death (BD) produces immunological and hemodynamic disorders that affect organ viability. Following BD, female rats are associated with increased renal inflammation interrelated with female sex hormone reduction. Here, the aim was to investigate the effects of sex on BD-induced Acute Kidney Injury (AKI) using an Isolated Perfused rat Kidney (IPK) model. METHODS: Wistar rats, females, and males (8 weeks old), were maintained for 4h after BD. A left nephrectomy was performed and the kidney was preserved in a cold saline solution (30 min). IPK was performed under normothermic temperature (37°C) for 90 min using WME as perfusion solution. AKI was assessed by morphological analyses, staining of complement system components and inflammatory cell markers, perfusion flow, and creatinine clearance. RESULTS: BD-male kidneys had decreased perfusion flow on IPK, a phenomenon that was not observed in the kidneys of BD-females (p < 0.0001). BD-male kidneys presented greater proximal (p = 0.0311) and distal tubule (p = 0.0029) necrosis. However, BD-female kidneys presented higher expression of eNOS (p = 0.0060) and greater upregulation of inflammatory mediators, iNOS (p = 0.0051), and Caspase-3 (p = 0.0099). In addition, both sexes had increased complement system formation (C5b-9) (p=0.0005), glomerular edema (p = 0.0003), and nNOS (p = 0.0051). CONCLUSION: The present data revealed an important sex difference in renal perfusion in the IPK model, evidenced by a pronounced reduction in perfusate flow and low eNOS expression in the BD-male group. Nonetheless, the upregulation of genes related to the proinflammatory cascade suggests a progressive inflammatory process in BD-female kidneys.

Comparison of acute kidney injury following brain death between male and female rats

Abstract Background Clinical reports associate kidneys from female donors with worse prognostic in male recipients. Brain Death (BD) produces immunological and hemodynamic disorders that affect organ viability. Following BD, female rats are associated with increased renal inflammation interrelated with female sex hormone reduction. Here, the aim was to investigate the effects of sex on BD-induced Acute Kidney Injury (AKI) using an Isolated Perfused rat Kidney (IPK) model. Methods Wistar rats, females, and males (8 weeks old), were maintained for 4h after BD. A left nephrectomy was performed and the kidney was preserved in a cold saline solution (30 min). IPK was performed under normothermic temperature (37°C) for 90 min using WME as perfusion solution. AKI was assessed by morphological analyses, staining of complement system components and inflammatory cell markers, perfusion flow, and creatinine clearance. Results BD-male kidneys had decreased perfusion flow on IPK, a phenomenon that was not observed in the kidneys of BD-females (p< 0.0001). BD-male kidneys presented greater proximal (p= 0.0311) and distal tubule (p= 0.0029) necrosis. However, BD-female kidneys presented higher expression of eNOS (p= 0.0060) and greater upregulation of inflammatory mediators, iNOS (p= 0.0051), and Caspase-3 (p= 0.0099). In addition, both sexes had increased complement system formation (C5b-9) (p=0.0005), glomerular edema (p= 0.0003), and nNOS (p= 0.0051). Conclusion The present data revealed an important sex difference in renal perfusion in the IPK model, evidenced by a pronounced reduction in perfusate flow and low eNOS expression in the BD-male group. Nonetheless, the upregulation of genes related to the proinflammatory cascade suggests a progressive inflammatory process in BD-female kidneys.

Modulatory effects of 17ß-estradiol on acute lung inflammation after total occlusion of the descending aorta in male rats.

As a consequence of systemic inflammation caused by ischemia and reperfusion (I/R) due to aortic occlusion, the lungs can exhibit increased microvascular permeability, local release of pro-inflammatory mediators, and leukocyte infiltration. Lung tissue infiltration by activated neutrophils is followed by acute respiratory distress syndrome, which is linked to acute pulmonary microvascular damage, high mortality rates, and organ dysfunction. Previous studies have demonstrated that female sex hormones modulate the inflammatory response and that prophylactic treatment with 17ß-estradiol (E2) can prevent fatalities and preserve mesenteric perfusion and intestinal integrity after ischemia/reperfusion induced by aortic occlusion. In this study, we focused on the protective effects of estradiol after aortic ischemia/reperfusion by evaluating lung injury and endothelial alterations. Upon anesthesia and mechanical ventilation, male rats were subjected to aortic occlusion for 20 min, followed by 2 h of reperfusion. In parallel, one group of rats received a single injection of estradiol (280 µg/kg, i.v.) 30 min before ischemia. We observed increased serum concentrations of IL-1ß, IL-6 and IL-10 in the I/R rats and E2 was able to reduce them. E2 effects after 2 h of reperfusion resulted mainly in decreasing of edema, iNOS expression and preventing leukocyte infiltration. Overall, our data indicate that estradiol might be a supplementary approach to deal with systemic processes and lung deterioration.

Long-term lung inflammation is reduced by estradiol treatment in brain dead female rats.

OBJECTIVES: Lung transplantation is limited by the systemic repercussions of brain death (BD). Studies have shown the potential protective role of 17ß-estradiol on the lungs. Here, we aimed to investigate the effect of estradiol on the long-lasting lung inflammatory state to understand a possible therapeutic application in lung donors with BD. METHODS: Female Wistar rats were separated into 3 groups: BD, subjected to brain death (6h); E2-T0, treated with 17ß-estradiol (50 µg/mL, 2 mL/h) immediately after brain death; and E2-T3, treated with 17ß-estradiol (50 µg/ml, 2 ml/h) after 3h of BD. Complement system activity and macrophage presence were analyzed. TNF-α, IL-1ß, IL-10, and IL-6 gene expression (RT-PCR) and levels in 24h lung culture medium were quantified. Finally, analysis of caspase-3 gene and protein expression in the lung was performed. RESULTS: Estradiol reduced complement C3 protein and gene expression. The presence of lung macrophages was not modified by estradiol, but the release of inflammatory mediators was reduced and TNF-α and IL-1ß gene expression were reduced in the E2-T3 group. In addition, caspase-3 protein expression was reduced by estradiol in the same group. CONCLUSIONS: Brain death-induced lung inflammation in females is modulated by estradiol treatment. Study data suggest that estradiol can control the inflammatory response by modulating the release of mediators after brain death in the long term. These results strengthen the idea of estradiol as a therapy for donor lungs and improving transplant outcomes.

Protective role of 17ß-estradiol treatment in renal injury on female rats submitted to brain death.

BACKGROUND: Clinical and experimental data highlight the consequences of brain death on the quality of organs and demonstrate the importance of donor state to the results of transplantation. Female rats show higher cardio-pulmonary injury linked to decreased concentrations of female sex hormones after brain-dead (BD). This study evaluated the effect of 17ß-estradiol on brain death induced renal injury in female rats. METHODS: Female Wistar rats were randomically allocated into 4 groups: false-operation (Sham), BD, treatment with 17ß-estradiol (50 µg/mL, 2 mL/h) 3 h after brain death (E2-T3), or immediately after brain death confirmation (E2-T0). Creatinine, urea, cytokines, and complement system components were quantified. Renal injury markers, such as KIM-1, Caspase-3, BCL-2 and MMP2/9 were evaluated. RESULTS: Brain death leads to increased kidney KIM-1 expression and longer 17ß-estradiol treatment resulted in downregulation (P<0.0001). There was increase of neutrophil numbers in kidney from BD rats and E2 treatment was able to reduce it (P=0.018). Regarding complement elements, E2-T3 group evidenced E2 therapeutic effects, reducing C5b-9 (P=0.0004), C3aR (P=0.054) and C5aR (P=0.019). In parallel, there were 17ß-estradiol effects in reducing MMP2 (P=0.0043), MMP9 (P=0.011), and IL-6 (P=0.024). Moreover, E2-T3 group improved renal function in comparison to BD group (P=0.0938). CONCLUSIONS: 17ß-estradiol treatment was able to reduce acute kidney damage in BD female rats owing to its ability to prevent tissue damage, formation of C5b-9, and local synthesis of inflammatory mediators.

Long-term lung inflammation is reduced by estradiol treatment in brain dead female rats

OBJECTIVES: Lung transplantation is limited by the systemic repercussions of brain death (BD). Studies have shown the potential protective role of 17β-estradiol on the lungs. Here, we aimed to investigate the effect of estradiol on the long-lasting lung inflammatory state to understand a possible therapeutic application in lung donors with BD. METHODS: Female Wistar rats were separated into 3 groups: BD, subjected to brain death (6h); E2-T0, treated with 17β-estradiol (50 μg/mL, 2 mL/h) immediately after brain death; and E2-T3, treated with 17β-estradiol (50 μg/ml, 2 ml/h) after 3h of BD. Complement system activity and macrophage presence were analyzed. TNF-α, IL-1β, IL-10, and IL-6 gene expression (RT-PCR) and levels in 24h lung culture medium were quantified. Finally, analysis of caspase-3 gene and protein expression in the lung was performed. RESULTS: Estradiol reduced complement C3 protein and gene expression. The presence of lung macrophages was not modified by estradiol, but the release of inflammatory mediators was reduced and TNF-α and IL-1β gene expression were reduced in the E2-T3 group. In addition, caspase-3 protein expression was reduced by estradiol in the same group. CONCLUSIONS: Brain death-induced lung inflammation in females is modulated by estradiol treatment. Study data suggest that estradiol can control the inflammatory response by modulating the release of mediators after brain death in the long term. These results strengthen the idea of estradiol as a therapy for donor lungs and improving transplant outcomes.

Treatment with 17ß-estradiol protects donor heart against brain death effects in female rat.

The viability of donor organs is reduced by hemodynamic and immunologic alterations caused by brain death (BD). Female rats show higher heart inflammation associated with the reduction in female sex hormones after BD. This study investigated the effect of 17ß-estradiol (E2) on BD-induced cardiac damage in female rats. Groups of female Wistar rats were assigned: Sham-operation (Sham), brain death (BD), treatment with E2 (50 µg/ml, 2 ml/h) 3 h after BD (E2-T3), or immediately after BD confirmation (E2-T0). White blood cell (WBC) count was analyzed; cytokines and troponin-I were quantified. Heart histopathological changes and expression of endothelial nitric oxide synthase, endothelin-1, intercellular adhesion molecule-1, BCL-2, and caspase-3 were evaluated. Cardiac function was continuously assessed for 6 h by left ventricular pressure-volume loop analysis. E2 decreased the BD-induced median serum concentration of troponin-I (BD:864.2 vs. E2-T0:401.4; P = 0.009), increased BCL-2 (BD:0.086 vs. E2-T0:0.158; P = 0.0278) and eNOS median expression in the cardiac tissue (BD:0.001 vs. E2-T0:0.03 and E2-T3:0.0175; P < 0.0001), and decreased caspase-3 (BD:0.025 vs. E2-T0:0.006 and E2-T3:0.019; P = 0.006), WBC counts, leukocyte infiltration, and hemorrhage. 17ß-estradiol treatment was effective in reducing cardiac tissue damage in brain-dead female rats owing to its ability to reduce leukocyte infiltration and prevent cardiomyocyte apoptosis.

The influence of female sex hormones on lung inflammation after brain death - an experimental study.

Organ donor's age negatively influences graft survival of organs, increasing risk of complications. Aging occurs in both men and women; however, the menopause marks a decrease in sex hormones and a sudden increase in the process of vascular aging. We investigated sex hormones' influence on the lung inflammatory process induced by BD in female rats. Wistar rats were grouped as: female rats from high estradiol to heat period (non-OVx) and ovariectomized (OVx) female rats. Ovariectomy was carried out 10 days before BD. BD was induced using intracranial balloon rapid inflation. Serum hormones and inflammatory mediators were quantified, leukocytes and platelets counted and lung samples were collected for RT-PCR, immunohistochemical, and histological analysis. Female sex hormones and corticosterone were reduced 6 h after BD in non-OVx group. The infiltration of leukocytes in female non-OVx lungs was higher compared to OVx. G-CSF, VEGF, and CINC-1 were found increased in non-OVx group serum in comparison to OVx. Lung mediators were increased in non-OVx rats compared to controls. The acute reduction of sex hormones induced by BD appears to have a worse effect on lung inflammation than a reduction that has happened over a prolonged period of time, allowing a physiological adaptation prior to BD.

17ß-Estradiol protects against lung injuries after brain death in male rats.

BACKGROUND: Brain death elicits microvascular dysfunction and inflammation, and thereby compromises lung viability for transplantation. As 17ß-estradiol was shown to be anti-inflammatory and vascular protective, we investigated its effects on lung injury after brain death in male rats. METHODS: Wistar rats were assigned to: sham-operation by trepanation only (SH, n = 7); brain death (BD, n = 7); administration of 17ß-estradiol (280 µg/kg, iv) at 60 minutes after brain death (BD-E2, n = 7). Experiments were performed 180 minutes thereafter. Histopathological changes in the lung were evaluated by histomorphometry. Gene expression of inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), and endothelin-1 was measured by real-time polymerase chain reaction. Protein expression of NO synthases, endothelin-1, platelet endothelial cell adhesion molecule-1 (PECAM-1), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), BCL-2, and caspase 3 was assessed by immunohistochemistry. Cytokines were quantified by enzyme-linked immunosorbent assay. RESULTS: Treatment with 17ß-estradiol after brain death decreased lung edema and hemorrhage (p < 0.0001), and serum levels of cytokine-induced neutrophil chemoattractant-1 (CINC-1; p = 0.0020). iNOS (p < 0.0001) and VCAM-1 (p < 0.0001) also diminished at protein levels, while eNOS accumulated (p = 0.0002). However, gene expression of iNOS, eNOS, and endothelin-1 was comparable among groups, as was protein expression of endothelin-1, ICAM-1, BCL-2, and caspase 3. CONCLUSIONS: 17ß-Estradiol effectively reduces lung injury in brain-dead rats mainly due to its ability to regulate NO synthases. Thus, the drug may improve lung viability for transplantation.

Differential Effects of Brain Death on Rat Microcirculation and Intestinal Inflammation: Female Versus Male.

Brain death (BD) affects organs by multiple mechanisms related to hemodynamic effects, hormonal changes, and the systemic inflammatory response, which reduce organ function and viability. BD reduces microcirculatory perfusion in rat mesentery; this disturbance is also observed in the pancreas and lungs. Sex hormones can affect microcirculatory function, altering tissue perfusion and influencing the inflammatory process. Here, we present differences between sexes in the microcirculatory alterations generated by BD and in inflammatory infiltrate. Male, female, and ovariectomized-female Wistar rats were submitted to BD by intracranial balloon catheter sudden inflation. BD was confirmed by maximally dilated and fixed pupils, apnea, absence of reflexes, and a drop in mean arterial pressure. Perfusion and flow of the mesenteric microcirculation were analyzed. Intestinal myeloperoxidase activity and leukocyte infiltration were quantified. ELISA quantified serum estradiol, corticosterone, and inflammatory mediators, whereas expression of eNOS, endothelin, and endothelial adhesion molecule was measured by immunohistochemistry. Male rats presented lower percentages of mesenteric perfused microvessels and reduced blood flow compared to females. The female group presented higher eNOS and endothelin expression. Leukocyte infiltration into intestinal walls was higher in females in comparison to that in males. Moreover, the female group showed higher mesenteric vessel ICAM-1 expression than males, whereas serum TNF-α, IL-1ß, and IL-10 levels did not differ between sexes. The high estradiol concentration before BD and high eNOS expression apparently favored the maintenance of microvascular perfusion/flow; however, BD caused an acute reduction of female sex hormone concentration and higher ICAM-1 level; thus, the proinflammatory organ status after BD is favored.