Higher sclerostin is associated with pulmonary hypertension in pre-dialysis end-stage kidney disease patients: a cross-sectional prospective observational cohort study.

BACKGROUND: Pulmonary hypertension (PH) is a complication of chronic kidney disease (CKD) that contributes to mortality. Sclerostin, a SOST gene product that reduces osteoblastic bone formation by inhibiting Wnt/ß-catenin signaling, is involved in arterial stiffness and CKD-bone mineral disease, but scanty evidence to PH. This study explored the relationship between sclerostin and PH in CKD 5, pre-dialysis end-stage kidney disease (ESKD) patients. METHODS: This cross-sectional prospective observational cohort study included 44 pre-dialysis ESKD patients between May 2011 and May 2015. Circulating sclerostin levels were measured using an enzyme-linked immunosorbent assay. PH was defined as an estimated pulmonary artery systolic pressure > 35 mmHg on echocardiography. RESULTS: Patients with higher sclerostin levels ≥ 218.18pmol/L had echocardiographic structural cardiac abnormalities, especially PH (P < 0.01). On multivariate logistic analysis, sclerostin over 218.19pmol/L was significantly associated with PH (odds ratio [OR], 41.14; 95% confidence interval [CI], 4.53-373.89, P < 0.01), but multivariate Cox regression analysis showed the systemic vascular calcification score over 1 point (Hazard ratio [HR] 11.49 95% CI 2.48-53.14, P = 0.002) and PH ([HR] 5.47, 95% CI 1.30-23.06, P = 0.02) were risk factors for all-cause mortality in pre-dialysis ESKD patients. CONCLUSIONS: Serum sclerostin and PH have a positive correlation in predialysis ESKD patients. The higher systemic vascular calcification score and PH have an association to increase all-cause mortality in pre-dialysis ESKD patients.

The Impact of Obesity on Kidney Disease: Observational Cohort Study Analyzing 14,492 Kidney Biopsy Cases.

BACKGROUND: The obesity epidemic is associated with the emergence of new kidney diseases including obesity-related glomerulopathy (ORG) and metabolic syndrome-associated disorders. However, the effects of obesity on prevalence and outcome of biopsy-proven kidney disease are not well known. METHODS: We analyzed 14,492 kidney biopsies in 18 hospitals from 1979 to 2018 in Korea. Obesity was defined as a body mass index value of ≥ 30 kg/m². RESULTS: The most common disease was IgA nephropathy (IgAN) in both obese and non-obese participants (33.7% vs. 38.9%). Obesity was associated with a higher risk of focal segmental glomerulosclerosis (FSGS) and hypertensive nephropathy (HT-N) (odds ratio [OR], 1.72, 95% confidence interval [CI], 1.37-2.17; OR, 1.96, 95% CI, 1.21-3.19) and a lower risk of IgAN (OR, 0.74, 95% CI, 0.62-0.88). During the median follow up of 93.1 ± 88.7 months, obesity increased the risk of end-stage kidney disease (ESKD) in patients with IgAN (relative risk [RR], 1.49, 95% CI, 1.01-2.20) and lupus nephritis (LN) (RR, 3.43, 95% CI, 1.36-8.67). Of 947 obese individuals, ORG was detected in 298 (31.5%), and 230 participants had other kidney diseases, most commonly, IgAN (40.9%) followed by diabetic nephropathy (15.2%). Participants with ORG, when combined with other renal diseases, showed higher risks for developing ESKD compared to those with ORG alone (RR, 2.48, 95% CI, 1.09-5.64). CONCLUSION: Obesity is associated with an increased risk of FSGS and HT-N, and also increase the ESKD risk in IgAN and LN patients. ORG in obese participants may have favorable renal outcomes if it occurs alone without any other renal disease.

Role of the Circadian Clock and Effect of Time-Restricted Feeding in Adenine-Induced Chronic Kidney Disease.

Most physiological functions exhibit circadian rhythmicity that is partly regulated by the molecular circadian clock. Herein, we investigated the relationship between the circadian clock and chronic kidney disease (CKD). The role of the clock gene in adenine-induced CKD and the mechanisms of interaction were investigated in mice in which Bmal1, the master regulator of the clock gene, was knocked out, and Bmal1 knockout (KO) tubule cells. We also determined whether the renoprotective effect of time-restricted feeding (TRF), a dietary strategy to enhance circadian rhythm, is clock gene-dependent. The mice with CKD showed altered expression of the core clock genes with a loss of diurnal variations in renal functions and key tubular transporter gene expression. Bmal1 KO mice developed more severe fibrosis, and transcriptome profiling followed by gene ontology analysis suggested that genes associated with the cell cycle, inflammation, and fatty acid oxidation pathways were significantly affected in the mutant mice. Tubule-specific deletion of BMAL1 in HK-2 cells by CRISPR/Cas9 led to upregulation of p21 and tumor necrosis α and exacerbated epithelial-mesenchymal transition-related gene expression upon transforming growth factor ß stimulation. Finally, TRF in the mice with CKD partially restored the disrupted oscillation of the kidney clock genes, accompanied by improved cell cycle arrest and inflammation, leading to decreased fibrosis. However, the renoprotective effect of TRF was abolished in Bmal1 KO mice, suggesting that TRF is partially dependent on the clock gene. Our data demonstrate that the molecular clock system plays an important role in CKD via cell cycle regulation and inflammation. Understanding the role of the circadian clock in kidney diseases can be a new research field for developing novel therapeutic targets.

A Case Report of Thrombotic Thrombocytopenia After ChAdOx1 nCov-19 Vaccination and Heparin Use During Hemodialysis.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but life-threatening complication. VITT strongly mimics heparin-induced thrombocytopenia (HIT) and shares clinical features. Heparin is commonly used to prevent coagulation during hemodialysis. Therefore, nephrologists might encounter patients needing dialysis with a history of heparin exposure who developed thrombotic thrombocytopenia after vaccination. A 70-year-old male presented with acute kidney injury and altered mental status due to lithium intoxication. He needed consecutive hemodialysis using heparin. Deep vein thrombosis of left lower extremity and accompanying severe thrombocytopenia of 15,000/µL on 24 days after vaccination and at the same time, nine days after heparin use. Anti-platelet factor 4 antibody test was positive. Anticoagulation with apixaban and intravenous immunoglobulin (IVIG) infusion resolved swelling of his left calf and thrombocytopenia. There were no definitive diagnostic tools capable of differentiating between VITT and HIT in this patient. Although VITT and HIT share treatment with IVIG and non-heparin anticoagulation, distinguishing between VITT and HIT will make it possible to establish a follow-up vaccination plan in a person who has had a thrombocytopenic thrombotic event. Further research is needed to develop the tools to make a clear distinction between the clinical syndromes.

Intestinal microbiota control acute kidney injury severity by immune modulation.

Intestinal microbiota impacts the host immune system and influences the outcomes of chronic diseases. However, it remains uncertain whether acute kidney injury (AKI) impacts intestinal microbiota or vice versa. To determine this, we investigated the mechanistic link between AKI, microbiota, and immune response in ischemia/reperfusion injury. Microbiota alteration and its biological consequences after ischemia/reperfusion injury were examined and the effect of dysbiotic microbiota on the outcome of AKI was also assessed by colonizing germ-free mice with post-AKI microbiota. The role of Th17, Th1, Tregs cells and macrophage polarization in mediating the renoprotective effect of antibiotic induced microbiota depletion in ischemia/reperfusion injury was also determined. Increase of Enterobacteriacea, decrease of Lactobacilli, and Ruminococacceae were found to be the hallmarks of ischemia/reperfusion injury induced dysbiosis and were associated with a decreased levels of short-chain fatty acids, intestinal inflammation and leaky gut. Colonizing germ-free mice with post-AKI microbiota worsened ischemia/reperfusion injury severity with exaggerated inflammation in recipient mice compared to colonizing with microbiota from sham operated mice. Microbiota depletion by oral antibiotics protected against ischemia/reperfusion injury. This renoprotective effect was associated with reduced Th 17, Th 1 response along with expansion of regulatory T cells, and M2 macrophages. Our study demonstrated a unique bidirectional relationship between the kidney and the intestine during AKI. Intestinal dysbiosis, inflammation and leaky gut are consequences of AKI but they also represent an important modifier determining post-AKI severity. Thus, targeting the intestinal microbiota might provide a novel therapeutic strategy in AKI.

Long-term Renal Outcome of Biopsy-proven Acute Tubular Necrosis and Acute Interstitial Nephritis.

BACKGROUND: Although emerging evidence suggest acute kidney injury (AKI) progress to chronic kidney disease (CKD), long-term renal outcome of AKI still remains unclear. Acute tubular necrosis (ATN) is the most common cause of AKI due to ischemia, toxin or sepsis. Acute interstitial nephritis (AIN), caused by drugs or autoimmune diseases is also increasingly recognized as an important cause of AKI. Unlike glomerular diseases, AKI is usually diagnosed in the clinical context without kidney biopsies, and lack of histology might contribute to this uncertainty. METHODS: Among 8,769 biopsy series, 253 adults who were histologically diagnosed with ATN and AIN from 1982 to 2018 at five university hospitals were included. Demographic and pathological features that are associated with the development of end stage renal disease (ESRD) were also examined. RESULTS: Rate of non-recovery of renal function at 6 month was significantly higher in the AIN (ATN vs AIN 49.3 vs 69.4%, P = 0.007) with a 2.71-fold higher risk of non- recovery compared to ATN (95% confidence interval [CI], 1.20-6.47). During the mean follow up of 76.5 ± 91.9 months, ESRD developed in 39.4% of patients with AIN, and 21.5% patients of ATN. The risk of ESRD was significantly higher in AIN (23.05; 95% CI, 2.42-219.53) and also in ATN (12.14; 95% CI, 1.19-24.24) compared to control with non-specific pathology. Older age, female gender, renal function at the time of biopsy and at 6 months, proteinuria and pathological features including interstitial inflammation and fibrosis, tubulitis, vascular lesion were significantly associated with progression to ESRD. CONCLUSION: Our study demonstrated that patients with biopsy proven ATN and AIN are at high risk of developing ESRD. AIN showed higher rate of non-renal recovery at 6 month than ATN.

Intestinal barrier disruption and dysregulated mucosal immunity contribute to kidney fibrosis in chronic kidney disease.

BACKGROUND: Emerging evidence suggests that intestinal dysbiosis is associated with diverse pathological processes. In this study we demonstrated intestinal barrier disruption and aberrant mucosal immunity in 5/6 nephrectomized mice and the effect of probiotics on chronic kidney disease (CKD). METHODS: CKD was induced in 6-week-old mice by 5/6 nephrectomy. They were fed a lactobacilli mixture for 8 weeks. Serum, urine and stool samples were collected for renal function assessments and gut microbiome analyses. Gut permeability, colon heat shock protein 70 (HSP70) and colon epithelial integrity were evaluated and cytokine levels in colon and kidney were measured. Colon leukocytes were analyzed by flow cytometry and bone marrow-derived cells were cocultured with lactobacilli mixture. RESULTS: In CKD mice, 'leaky gut' was accompanied by decreased colon HSP70 and claudin-1 expression, whereas it increased pore-forming claudin-2 expression and apoptosis. Although the percentage of regulatory T cells did not differ between CKD and control mice, cytokine expression and the ratio of CX3CR1intermediate:CX3CR1high pro-inflammatory/resident macrophages increased in the colon of CKD mice. Orally administered lactobacilli partially mitigated the CKD-induced 'leaky gut'; restored colon epithelial HSP70, claudin-1 and claudin-2 expression and decreased apoptosis. Probiotic treatment also restored the CX3CR1intermediate:CX3CR1high macrophage ratio and increased circular dichroism (CD)103+CD11c+ regulatory dendritic cells in the colon. These changes suppressed systemic inflammation and kidney fibrosis. CONCLUSIONS: Our results suggest that intestinal dysbiosis-associated gut barrier disruption and aberrant mucosal immunity are important for the systemic inflammation and progressive fibrosis of CKD. Targeting the intestine might provide novel therapeutic opportunities for CKD.

ADAMTS13-von Willebrand factor axis is involved in the pathophysiology of kidney ischaemia-reperfusion injury.

AIM: The ADAMTS13-von Willebrand factor (vWF) axis has been suggested to play a critical role in the pathophysiology of ischaemia-reperfusion injury (IRI) in the heart or brain. Therefore, we aimed to investigate whether this axis was involved in the pathophysiology of IRI-induced acute kidney injury. METHODS: We performed renal IRI in ADAMTS13 knockout (KO) or wild type (WT) mice. Functional and histological kidney damage, and inflammation were compared and the effect of anti-vWF antibodies in ADAMTS13 KO mice was assessed. RESULTS: Following IRI, the blood and kidney ADAMTS13 levels were significantly decreased. vWF expression was significantly upregulated in both the medulla and cortex of injured kidneys as shown by immunohistochemistry and western blot analyses. There was also an increased level of vWF dimers after IRI. In ADAMTS13 KO mice, kidney vWF levels were further increased and this was associated with greater endothelial and epithelial injury compared to WT mice, suggesting an important role of vWF in renal IRI. In addition, the number of Gr-1+ neutrophils was significantly higher in the kidneys of ADAMTS13 KO mice compared to WT mice, whereas F4/80 macrophage numbers were unchanged. In ADAMTS13 KO mice, administration of anti-vWF antibodies after IRI partially reversed renal injury. CONCLUSION: Our data show that the ADAMTS13-vWF axis is partially involved in the pathophysiology of kidney IRI, suggesting that regulating ADAMTS13- and vWF-dependent mechanisms could have therapeutic potential to limit renal IRI.

Fate of Neutrophils during the Recovery Phase of Ischemia/Reperfusion Induced Acute Kidney Injury.

Effective clearance of inflammatory cells is required for resolution of inflammation. Here, we show in vivo evidence that apoptosis and reverse transendothelial migration (rTEM) are important mechanisms in eliminating neutrophils and facilitating recovery following ischemia/reperfusion injury (IRI) of the kidney. The clearance of neutrophils was delayed in the Bax knockout (KO)(BM) → wild-type (WT) chimera in which bone marrow derived cells are partially resistant to apoptosis, compared to WT(BM) → WT mice. These mice also showed delayed functional, histological recovery, increased tissue cytokines, and accelerated fibrosis. The circulating intercellular adhesion molecule-1 (ICAM-1)⁺ Gr-1⁺ neutrophils displaying rTEM phenotype increased during the recovery phase and blockade of junctional adhesion molecule-C (JAM-C), a negative regulator of rTEM, resulted in an increase in circulating ICAM-1⁺ neutrophils, faster resolution of inflammation and recovery. The presence of Tamm-Horsfall protein (THP) in circulating ICAM-1⁺ neutrophils could suggest that they are derived from injured kidneys. In conclusion, we suggest that apoptosis and rTEM are critically involved in the clearance mechanisms of neutrophils during the recovery phase of IRI.

Clinical Practice Guidelines for the Management of Atypical Hemolytic Uremic Syndrome in Korea.

Atypical hemolytic uremic syndrome (aHUS) is a rare syndrome characterized by micro-angiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The major pathogenesis of aHUS involves dysregulation of the complement system. Eculizumab, which blocks complement C5 activation, has recently been proven as an effective agent. Delayed diagnosis and treatment of aHUS can cause death or end-stage renal disease. Therefore, a diagnosis that differentiates aHUS from other forms of thrombotic microangiopathy is very important for appropriate management. These guidelines aim to offer recommendations for the diagnosis and treatment of patients with aHUS in Korea. The guidelines have largely been adopted from the current guidelines due to the lack of evidence concerning the Korean population.

The heat-shock protein-70-induced renoprotective effect is partially mediated by CD4+ CD25+ Foxp3 + regulatory T cells in ischemia/reperfusion-induced acute kidney injury.

Recent reports suggest the presence of heat-shock protein (HSP)-reactive T cells with a regulatory phenotype in various inflammatory diseases. To test whether HSP exerts renoprotective effects through regulatory T cells (Tregs), ischemia/reperfusion injury was done with or without heat preconditioning in mice. Splenocytes from heat-preconditioned mice had Treg expansion and a reduced proliferative response upon mitogenic stimulus. T cells from heat-preconditioned mice failed to reconstitute postischemic injury when adoptively transferred to T cell-deficient nu/nu mice in contrast to those from control mice. Tregs were also increased in heat-preconditioned ischemic kidneys. Depleting Tregs before heat preconditioning abolished the renoprotective effect, while adoptive transfer of these cells back into Treg-depleted mice partially restored the beneficial effect of heat preconditioning. Inhibition of HSP70 by quercetin suppressed Treg expansion, as well as renoprotective effects. Transferring Tregs in quercetin-treated heat-preconditioned mice partially restored the beneficial effect of heat preconditioning. The specificity of immune cell HSP70 in renoprotection was confirmed by partial restoration of kidney injury when T cells from HSP70-deficient heat preconditioned mice were adoptively transferred to nu/nu mice. Thus, the renoprotective effect of HSP70 may be partially mediated by a direct immunomodulatory effect through Tregs. Better understanding of immunomodulatory mechanisms of various stress proteins might facilitate discovery of new preventive strategies in acute kidney injury.

Renoprotective effect of paricalcitol via a modulation of the TLR4-NF-κB pathway in ischemia/reperfusion-induced acute kidney injury.

BACKGROUND: The pathophysiology of ischemic acute kidney injury (AKI) is thought to include a complex interplay between vascular endothelial cell dysfunction, inflammation, and tubular cell damage. Several lines of evidence suggest a potential anti-inflammatory effect of vitamin D in various kidney injury models. In this study, we investigated the effect of paricalcitol, a synthetic vitamin D analog, on renal inflammation in a mouse model of ischemia/reperfusion (I/R) induced acute kidney injury (AKI). METHODS: Paricalcitol was administered via intraperitoneal (IP) injection at 24h before ischemia, and then I/R was performed through bilateral clamping of the renal pedicles. Twenty-four hours after I/R, mice were sacrificed for the evaluation of injury and inflammation. Additionally, an in vitro experiment using HK-2 cells was also performed to examine the direct effect of paricalcitol on tubular cells. RESULTS: Pre-treatment with paricalcitol attenuated functional deterioration and histological damage in I/R induced AKI, and significantly decreased tissue neutrophil and macrophage infiltration and the levels of chemokines, the pro-inflammatory cytokine interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1). It also decreased IR-induced upregulation of Toll-like receptor 4 (TLR4), and nuclear translocation of p65 subunit of NF-κB. Results from the in vitro study showed pre-treatment with paricalcitol suppressed the TNF-α-induced depletion of cytosolic IκB in HK-2 cells. CONCLUSION: These results demonstrate that pre-treatment with paricalcitol has a renoprotective effect in ischemic AKI, possibly by suppressing TLR4-NF-κB mediated inflammation.

Soluble CD25 is increased in patients with sepsis-induced acute kidney injury.

AIM: Sepsis has been shown to induce the expansion of CD4+CD25+ regulatory T cells (Tregs), and this paradoxical immune suppression has been suggested to be closely associated with the development of sepsis-induced organ dysfunction. In the present study, we aimed to investigate the possible link between immune suppression and the development of septic acute kidney injury (AKI). METHODS: We prospectively enrolled patients with a diagnosis of sepsis, with or without AKI and as well as patients with AKI but without sepsis. Serum and urine samples at the time of the diagnosis were collected to measure neutrophil gelatinase-associated lipocalin (NGAL), cytokines, and soluble CD25 (sCD25). RESULTS: Of the 82 patients enrolled, 44, 18, and 20 patients were classified into septic-AKI, sepsis-non AKI and non-septic AKI groups. There were no differences in the baseline characteristics in all three groups and the severity of infection in the two sepsis groups. Serum levels of interleukin (IL)-10 were significantly elevated in patients with septic-AKI compared to the other two groups. Serum and urine NGAL levels and the level of serum sCD25, a marker of regulatory T cells, were significantly elevated in patients with septic AKI group, indicating the potential association of paradoxical immune suppression and the development of septic-AKI. CONCLUSIONS: These results suggest that immune suppression in sepsis may be closely linked to the development of AKI and that sCD25 or IL-10 may be useful as novel biomarkers for the development of septic AKI.

The incidence and risk factors of acute kidney injury after hepatobiliary surgery: a prospective observational study.

BACKGROUND: Although intraperitoneal surgery is a major operation associated with postoperative acute kidney injury (AKI), the incidence, risk factors, and long-term renal outcome are not well known. We aimed to determine the risk factors and 6 months renal outcome in patients with clinical or subclinical AKI after hepatobiliary surgery. We also assessed the validity of urine neutrophil gelatinase-associated lipocalin (NGAL) in the early detection of AKI or prediction of renal outcome. METHODS: This prospective observational study enrolled patients with normal renal function who underwent hepatobiliary surgeries. Urine and serum samples were collected for NGAL measurement. RESULTS: Among 131 patients, 10 (7.6%) developed postoperative AKI. Urine NGAL at 12 h postsurgery was the most predictive parameter for the diagnosis of AKI (cutoff, 92.85 ng/mL). With the cutoff value, subclinical AKI was diagnosed in 42 (32.1%) patients. Patients with clinical AKI and those with subclinical AKI were assigned to the AKI group. The AKI group had significantly higher model for end-stage liver disease and sodium (MELD-Na) score, lower albumin level, and longer hospital stay after surgery than the non-AKI group. Older age and higher MELD-Na score were independent risk factors for the development of postoperative AKI. At 6 months postsurgery, the estimated glomerular filtration rate (eGFR) in the AKI group was significantly lower than that in the non-AKI group, although the baseline eGFR was not different. In multiple linear regression analysis, the maximum urine NGAL level during 24 h postsurgery, intraoperative fluid balance, and having liver transplantation were significantly associated with a poor 6 months renal outcome. CONCLUSION: Urine NGAL was useful in the early diagnosis of postoperative AKI as well as in predicting the 6 months renal outcome after hepatobiliary surgery. A considerable proportion of patients developed subclinical AKI, and these patients showed worse renal outcome compared with the non-AKI group.

IL-2/anti-IL-2 complex attenuates renal ischemia-reperfusion injury through expansion of regulatory T cells.

Regulatory T cells (Tregs) can suppress immunologic damage in renal ischemia-reperfusion injury (IRI), but the isolation and ex vivo expansion of these cells for clinical application remains challenging. Here, we investigated whether the IL-2/anti-IL-2 complex (IL-2C), a mediator of Treg expansion, can attenuate renal IRI in mice. IL-2C administered before bilateral renal IRI induced Treg expansion in both spleen and kidney, improved renal function, and attenuated histologic renal injury and apoptosis after IRI. Furthermore, IL-2C administration reduced the expression of inflammatory cytokines and attenuated the infiltration of neutrophils and macrophages in renal tissue. Depletion of Tregs with anti-CD25 antibodies abrogated the beneficial effects of IL-2C. However, IL-2C-mediated renal protection was not dependent on either IL-10 or TGF-ß. Notably, IL-2C administered after IRI also enhanced Treg expansion in spleen and kidney, increased tubular cell proliferation, improved renal function, and reduced renal fibrosis. In conclusion, these results indicate that IL-2C-induced Treg expansion attenuates acute renal damage and improves renal recovery in vivo, suggesting that IL-2C may be a therapeutic strategy for renal IRI.

Glucocorticoids attenuate septic acute kidney injury.

BACKGROUND: The incidence and mortality of septic acute kidney injury (AKI) remains high, whereas our understanding of pathogenesis for septic AKI is still limited. Glucocorticoids (GCs) have been clinically recommended for treatment of septic shock and also have showed favorable effect on septic AKI in several animal experiments. The aim of this study is to investigate the pathophysiology of septic AKI and the effect of GCs on septic AKI. METHODS: We induced septic AKI using cecal ligation and puncture (CLP) model in 8-10 wk-old male C57BL/6 mice. Saline or dexamethasone (2.5 mg/kg) dissolved in saline was administered after surgery. Hemodynamic, biochemical and histological changes were examined in a time-course manner. RESULTS: CLP resulted in hyperdynamic warm shock with multiple organ dysfunction including AKI. Despite renal dysfunction, light microscopy showed scanty acute tubular necrosis and inflammation. Instead, CLP induced significant increase in apoptosis of the kidney and spleen cells. In addition, septic kidneys showed mitochondrial injury and alterations in Bcl2 family proteins in the renal tubular cells. Dexamethasone treatment attenuated renal dysfunction, but it was not associated with improvement of hemodynamic parameters. Dexamethasone-induced organ protective effect was associated with reduced mitochondrial injury with preserved cytochrome c oxidase and suppression of proapoptotic proteins as well as reduced cytokine release. CONCLUSIONS: Mitochondrial damage and subsequent apoptosis are thought to play important role in the development of septic AKI. GCs might be a useful therapeutic strategy for septic AKI by reducing mitochondrial damage and apoptosis.

Role of inflammation in the pathogenesis of cardiorenal syndrome in a rat myocardial infarction model.

BACKGROUND: Cardiorenal syndrome is now frequently recognized, and the combined dysfunction of heart and kidney increases morbidity and mortality. This study aimed to investigate possible mechanisms that underlie renal damage following heart dysfunction using a rat myocardial infarction model, focusing on the inflammatory pathway. METHODS: Rats were randomized into four groups: normal, volume depletion, sham operation and myocardial infarction (MI). MI was induced by the ligation of the left coronary artery and a volume depletion model was produced by low-salt diet and furosemide injection. Biochemical, histological and flow cytometric analyses were performed at 3 days and 4 and 8 weeks after MI. RESULTS: On Day 3 following MI, the development of subclinical acute kidney injury was identified through significantly increased serum and urine neutrophil gelatinase-associated lipocalin level. We detected the increase of activated monocytes (CC chemokine receptor 2(+) ED-1(+)) in peripheral blood, along with the infiltration of ED-1(+) macrophages and the increment of nuclear p65 in the kidney of MI rats, suggesting the contribution of nuclear factor-kappa B-mediated inflammation in the development of Type 1 cardiorenal syndrome (CRS). The inflammatory cytokines, interleukin-6 and tumour necrosis factor-α (TNF-α) mRNA expression, as well as microvascular endothelial permeability and tubular cell apoptosis, significantly increased in the kidneys of MI rats. At 4 and 8 weeks after MI, tubular cell apoptosis, ED-1(+) macrophage infiltration and interstitial fibrosis increased in MI rats, and these chronic changes were significantly mitigated by systemic monocyte/macrophage depletion using liposome clodronate. CONCLUSION: This study identifies the possible important role of inflammatory response as a mediator of heart-kidney crosstalk in CRS.

The role of urinary liver-type fatty acid-binding protein in critically ill patients.

Although several urinary biomarkers have been validated as early diagnostic markers of acute kidney injury (AKI), their usefulness as outcome predictors is not well established. This study aimed to determine the diagnostic and prognostic abilities of urinary liver-type fatty acid-binding protein (L-FABP) in heterogeneous critically ill patients. We prospectively collected data on patients admitted to medical and surgical intensive care units (ICUs) from July 2010 to June 2011. Urine neutrophil gelatinase-associated lipocalin (NGAL) and L-FABP at the time of ICU admission were quantitated. Of the 145 patients, 54 (37.2%) had AKI defined by the Acute Kidney Injury Network (AKIN) criteria. AKI patients showed significantly higher level of urinary NGAL and L-FABP and also higher mortality than non-AKI patients. The diagnostic performances, assessed by the area under the ROC curve, were 0.773 for NGAL and 0.780 for L-FABP, demonstrating their usefulness in diagnosing AKI. In multivariate Cox analysis, urinary L-FABP was an independent predictor for 90-day mortality. Urinary L-FABP seems to be promising both for the diagnosis of AKI and for the prediction of prognosis in heterogeneous ICU patients. It needs to be further validated for clinical utility.

Postoperative hemolytic uremic syndrome with renal cortical necrosis following laparoscopic hemicolectomy.

Non-Shiga-like toxin-producing Escherichia coli (STEC) or atypical hemolytic uremic syndrome (aHUS) is observed in 5-10% of all hemolytic uremic syndrome (HUS) cases, and usually develops secondary to infections, malignancies, drugs, transplantation, pregnancy, and autoimmune disease. However, there has been no report on adult onset HUS initiated by surgical procedures except transplantation. We report a 66-year-old woman who incurred renal impairment on the first day after laparoscopic hemicolectomy. Hemolytic anemia, thrombocytopenia, absence of Shiga toxin associated disease, normal ADAMTS13 activity, and low serum C3 (not C4) were consistent with a diagnosis of aHUS. We performed plasma exchange with fresh frozen plasma. Nevertheless, deteriorated renal function was not recovered after the treatment. Although it is an uncommon postoperative complication, aHUS needs to be considered as a possible cause of acute kidney injury combined with thrombocytopenia and anemia after surgical procedures, considering its different treatment modality and poor outcomes.

Characteristics and management of thrombotic microangiopathy in kidney transplantation.

Thrombotic microangiopathy is not a rare complication of kidney transplantation and is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury with extensive thrombosis of the arterioles and capillaries. Various factors can cause thrombotic microangiopathy after kidney transplantation, including surgery, warm and cold ischemia-reperfusion injury, exposure to immunosuppressants, infection, and rejection. Many recent studies on atypical hemolytic uremic syndrome have described genetic abnormalities related to excessive activation of the alternative complement pathway. The affected patients' genetic backgrounds revealed significant genetic heterogeneity in several genes involved in complement regulation, including the complement factor H, complement factor H-related proteins, complement factor I, complement factor B, complement component 3, and CD46 genes in the alternative complement pathway. Although clinical studies have provided a better understanding of the pathogenesis of diseases, the diverse triggers present in the transplant environment can lead to thrombotic microangiopathy, along with various genetic predispositions, and it is difficult to identify the genetic background in various clinical conditions. Given the poor prognosis of posttransplant thrombotic microangiopathy, further research is necessary to improve the diagnosis and treatment protocols based on risk factors or genetic predisposition, and to develop new therapeutic agents.