Lipocalin Research Articles

Effect of ischemic postconditioning on renal injury induced by intestinal ischemia-reperfusion and expression of Nrf2 in mice

Objective To investigate the effect of ischemic postconditioning (IPO) on renal injury induced by intestinal ischemia-reperfusion (I/R) and the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in mice.Methods Thirty-six healthy male C57BL/6J mice,aged 9-12 weeks,were randomly divided into 3 groups ( n =12 each):sham operation group ( S group),I/R group,and IPO + I/R group ( group IPO).Intestinal I/R was produced by occlusion of superior mesenteric artery for 45 min followed by 2 h reperfusion.The mice underwent 3 cycles of 30 s reperfusion and 30 s ischemia at the end of 45 min ischemia before 2 h reperfusion.Blood samples were collected from carotid artery at 2 h of reperfusion and then the mice were sacrificed.The kidney was removed for microscopic examination.The pathological changes of the kidney were scored.The concentrations of serum blood urea nitrogen (BUN),creatinine (Cr) and neutrophil gelatinase-associated lipocalin (NGAL)were detected.The expression of Nrf2 and heme oxygenase- 1 ( HO- 1 ),superoxide dismutase (SOD) activity,and the content of malondialdehyde (MDA),TNF-α,IL-6 and IL-10 were determined in renal tissues.Results The concentrations of serum BUN,Cr and NGAL,MDA content and the expression of Nrf2 and HO- 1 were significantly higher,SOD activity was significantly lower,and the pathological score was significantly higher in group I/R that in group S ( P ＜ 0.05).The concentrations of serum BUN,Cr and NGAL and MDA content were significantly lower,the expression of Nrf2 and HO-1 and SOD activity were significantly higher,and the pathological score was significantly lower in group IPO that in group I/R ( P ＜0.05).There was no significant difference in the content of TNF-αα,IL-6 and IL-10 among all groups(P＞0.05).Conclusion IPO can alleviate the renal injury induced by intestinal I/R through promoting the expression of Nrf2 and up-regulating the expression of HO-1 in mice. Key words: Reperfusion injury; Mesenteric artery, superior; Kidney function tests; NF-E2-related factor 2; Ischemic postconditioning

Serum lipocalin-2 levels are increased in patients with psoriasis

The protein lipocalin (LCN)-2 is known to be related to insulin resistance, obesity and atherosclerotic diseases. Psoriasis is an inflammatory skin disease related to metabolic syndrome. The aim of this study was to examine the relationship between serum LCN2 levels and indicators for metabolic syndrome and inflammatory cytokine levels in patients with psoriasis. Serum LCN2 levels were measured in patients with psoriasis, atopic dermatitis (AD) or bullous pemphigoid (BP), and compared with those of healthy controls. Serum LCN2 levels were also compared with several indicators for metabolic syndrome, and with serum levels of interleukin (IL)-6 and tumour necrosis factor (TNF)-α, two markers of inflammation. Serum LCN2 levels in patients with psoriasis were significantly higher than those of healthy controls, but there was no significant correlation between serum LCN2 and body mass index. Serum LCN2 levels also correlated with serum IL-6 and TNF-α levels in patients with psoriasis. Serum LCN2 levels are a general indicator for increased inflammation in the patients with psoriasis.

The expression and significance of neutrophil genatinase-association lipocalin in kidney disease

Neutrophil genatinase-association lipocalin(NGAL)is a kind of lipocalin of binding proteins that seems to be a popular topic studied much recently,which at first was considered as endogenous bacteriostatic agent.It is bound up with the occurrence,development and prognosis of many kidney diseases.Therefore,it can provide new idea and method on clinical diagnosis and treatment by further study on expression and significance of NGAL in kidney diseases. Key words: Neutrophil genatinase-association lipocalin; Acute kidney injury; Chronic kidney diseases; Nephrotic syndrome

The clinic value of the fractional excretion rate of NGAL in type-2 diabetes patients

Objective To investigate the expression of neutrophil gelatinase-associated lipocalin(NGAL) in the urine and plasma of type-2 diabetes patients,to analyze the value of the fractional excretion rate of NGAL(Fe NGAL).Methods 118 cases with T2DM and 28 control subjects wereselected.The DM cases were divided into 3 groups according to urine albumin/creatinine ratio(UACR):64cases in normal albuminuria group,36 cases in microalbuminuria group,and 18 cases in macroalbuminuria group,respectively.Urinary and plasma NGAL were measured by ELISA.Fasting glucose,serum cystatin C(Cysc),glycohemoglobinA1c (HbA1c) were also measured.Fe NGAL was determined by Bolignano D formulae; Glomerular filtration rate (GFR) determined by Macisaac formulae.Results (1)Fe NGAL in T2DM was significantly higher,comparing with the controls; significant difference was also found among the three groups ( P＜0.05 ).(2) Fe NGAL was positively corelated with Cys C and UACR(R=0.279,0.485),but inversely corelated with GFR(R=-0.235).Conclusion Fe NGAL can reflect the damage of T2DM earlier than urine albumin or Urinary NGAL. Key words: Diabetes mellitus; Diabetic nephropathy; Neutrophil gelatinase-associated lipocalin ( NGAL ); The fractional excretion rate of NGAL(Fe NGAL)

Lipocalin (LCN2; NGAL)

Lipocalin (LCN2; NGAL)

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) and early diagnosis of paraquat poisoning patients with acute kidney injury

To explore the use of the urinary neutrophil gelatinase associated lipocalin (uNGAL) in the early diagnosis of paraquat poisoning patients with acute kidney injury (AKI). Eighty five patients were from the emergency department in our hospital. Five ml blood and urine were collected from each patient at 15 min, 2, 4, 6, 8, 10, 12, 18, 24, 36, 48 and 72 h, 5 and 7d after admission. The uNGAL levels of urine were detected with ELISA test and the SCr levels were measured with creatine oxidase assay. Sixty two cases of paraquat intoxication suffered from AKI, the incidence was 72.94% (62/85). The SCr levels of 62 cases with AKI at 18, 24, 36, 48, 72 h and 5, 7 d after admission increased significantly, as compared with the baseline value and control group (P < 0.01). At 24, 36, 48, 72 h and 5, 7 d after admission, there was significant difference of the SCr levels between AKI group and non-AKI group (P < 0.01). At 2 h after admission, the uNGAL level of urine in paraquat intoxication AKI group was (96.21 +/- 45.32) microg/L which was significantly higher than the baseline value. At 10, 12, 18, 24, 36, 48, 72 h and 5, 7 d after admission, the uNGAL levels of urine in AKI group and non-AKI group obviously enhanced, as compared with the baseline value and control group (P < 0.01 or P < 0.05). At all time points, there was significant difference of the uNGAL level between AKI group and non-AKI group (P < 0.01). The uNGAL level of urine in paraquat intoxication patients at 2 h after admission significantly enhanced, which is earlier than enhanced SCr. So the uNGAL level of urine may serve as early diagnostic biomarker for AKI induced by paraquat intoxication.

Neutrophil gelatinase-associated lipocalin (NGAL) urine concentrations may serve as an early diagnostic marker for the development of acute kidney injury in myocardial infarction patients – preliminary results

Neutrophil gelatinase-associated lipocalin (NGAL) urine concentrations may serve as an early diagnostic marker for the development of acute kidney injury in myocardial infarction patients – preliminary results

Gp130-Dependent Release of Acute Phase Proteins Is Linked to the Activation of Innate Immune Signaling Pathways

BackgroundElevated levels of acute phase proteins (APP) are often found in patients with cardiovascular diseases. In a previous study, we demonstrated the importance of the IL-6-gp130 axis -as a key regulator of inflammatory acute phase signaling in hepatocytes-for the development of atherosclerosis.Background/Principal FindingsGp130-dependent gene expression was analyzed in a previously established hepatocyte-specific gp130 knockout mouse model. We performed whole transcriptome analysis in isolated hepatocytes to measure tissue specific responses after proinflammatory stimulus with IL-6 across different time points. Our analyses revealed an unexpected small gene cluster that requires IL-6 stimulus for early activation. Several of the genes in this cluster are involved in different cell defense mechanisms. Thus, stressors that trigger both general stress and inflammatory responses lead to activation of a stereotypic innate cellular defense response. Furthermore, we identified a potential biomarker Lipocalin (LCN) 2 for the gp130 dependent early inflammatory response.Conclusions/SignificanceOur findings suggest a complex network of tightly linked genes involved in the early activation of different parts of the innate immune response including acute phase proteins, complement and coagulation cascade.

Chemical shift assignments, 3JHNHA coupling constants and secondary structure of HNGAL (Human Neutrophil Gelatinase-Associated Lipocalin) in its apo form.

Chemical shift assignments, 3JHNHA coupling constants and secondary structure of HNGAL (Human Neutrophil Gelatinase-Associated Lipocalin) in its apo form.

Early biomarkers for acute kidney injury

Acute kidney injury (AKI) represents a common and devastating problem in clinical medicine. The lack of early biomarkers for AKI has led to a delay in initiating potentially effective therapies.Identification of novel biomarkers for AKI has progressed to the clinical phase of the biomarker discovery process. The most promising AKI biomarkers include neutrophil gelatinase-associated lipocalin, IL-18, kidney injury molecule-1 and liver-type fatty acid binding protein. In this article, we review the study of neutrophil gelatinase-associated lipocalin,IL-18, kidney injury molecule-1 and liver-type fatty acid binding protein in recent years,in order to provide the theory basis for the clinical application of the early biomarkers for AKI. Key words: Acute kidney injury; Acute renal failure; Biomarker; IL-18; Kidney injury molecule-1; Liver-type fatty acid binding protein; Nephrotoxicity; Neutrophil gelatinase-associated lipocalin

Lipocalin (LCN2; NGAL)

Lipocalin (LCN2; NGAL)

Focus on Molecules: Tear lipocalin

1. Structure Tear lipocalin, or von Ebner’s gland protein, tear specific prealbumin, (GenBank Accession Number: BC074925; Ref Seq ID: NM_002297; PDB ID: 3EYC, 1XKI) is a 17.45 kDa member of a superfamily christened lipocalins because lipophiles are enclosed within their cup shaped cavity or calyx. Tear lipocalin is the predominant lipid carrier in human tears and is critical to functions involving lipids in protection of the ocular surface. The protein exploits a number of structural elements to bind an extremely broad range of ligands that includes a variety of lipids with long alkyl chains, charged moieties, and even polycyclic structures. At ~75 μM, tear lipocalin is second only to lysozyme as the most concentrated protein in human tears. Lipocalin-1 (LCN-1), the name of the gene that encodes tear lipocalin, resides in a lipocalin gene cluster on chromosome 9q34. Two other genes LCN1b and LCN1c are not translated. Three isoforms have been consistently identified in protein sequence data and mass spectrometry in human tears. Genetic polymorphism is unlikely to be the source of these isoforms; at least three laboratories have found only one identical cDNA sequence in several tissues. Mass spectrometry and protein sequencing data combined with the inter-study variability of other isoforms suggest proteolytic action on the major isoform may account for the other forms. In one study tear lipocalin was proffered as the predominant phosphoprotein in tears although phosphorylation of the major isoforms was not evident by mass spectrometry in another study.

Prediction of acute kidney injury complicated by sepsis with neutronphil gelatinase-associated lipocalin as an early marker

Objective To investigate the accuracy of NGAL in prediction of acute kidney injury (AKI) complicated by sepsis. Methods Blood and urine samples were collected at different time points in 74 sepsis patients, and 17 AKI patients were got from them.Cysteine Cys C levels were detected with Latex enhanced turbidimetric immunoassay (LETIA). Urine NGAL and Scr levels were detected with solid-phase sandwich enzyme-linked immunosorbent assay and creatinine enzymatic assay respectively. At the same time, 57 non-AKI patients were set as controls. Dynamic changes of urine NGAL and Scr were observed in sepsis patients in test and control group. ROC curve was used to evaluate the performance of AKI diagnosis by urinary NGAL.Results The Scr base line was (59. 38 ±16. 72) μmol/L.The median time of diagnose of AKI was 24 (12, 48) h past-sepsis diagnosis, while the Scr was(100. 35± 28. 26) μmol/L. Of the group, 17 cases of sepsis were diagnosed with AKI, accounting for 23% (17/74) prevalence. In sepsis group, base line value[(0. 61 ± 0. 15) mg/L] of serum Cys C was not upregulated at 2, 4 and 6 h, which was (0. 63 ± 0. 14) mg/L, (0. 68 ± 0. 16) mg/L and (0.65±0. 14) mg/L respectively. As to 8 h [(0. 85 ± 0. 22) mg/L], a slight upregulation was found with no significant difference (t = 1.63, P ＞ 0. 05).A trend of gradual increase of serum Cys C levels was found in sepsis AKI group at 12, 18, 24, 36, 48 and 72 h. A significant difference was found compared with base line (t = 2. 81, 2.98, 3.05, 3.11, 3. 38,3. 17,P ＜0.01). NGAL level[(96.21 ±45.32) μg/L] was significantly higher than base line value [(4. 98 ± 1.65) μg/L]. Subsequently, in each time point from the 2 h to 48 h, a trend of gradual increase in urinary NGAL levels was showed. The differences were significant compared with the baseline values (t =2. 74,2. 83,2. 91,3.04,3.15,3.22,3. 31,3.45,3.57 ,P ＜0. 01). Urinary NGAL levels of sepsis AKI group were significantly higher than those in non-AKI group at different time points with significant difference (t =2. 69,2. 73,2. 84,2. 96,3.02,3. 13,3.29,3.43,3.54,3.22,P ＜0. 01). ROC curve was selected to analyze diagnostic performance of urinary NGAL levels in AKI patients 2 h post-sepsis. Area under ROC curve was obtained as 0. 935, 95% confidence interval was 0. 683-0. 971. When cut-off value of urinary NGAL for patients 2 h post-sepsis was 50 μg/L, the sensitivity, specificity and accuracy were 94. 4%, 87. 5% and 96. 8% in AKI diagnosis respectively. Conclusions The occurrence of AKi can be accurately predicted by urinary NGAL levels 2 h post-sepsis , and its AKI diagnosis time is earlier than that of Scr. Urine NGAL can be used as early marker of AKI complicated by sepsis. Key words: Sepsis; Renal insufficiency, acute; Acute-phase proteins; Proto-oncogene proteins; Lipocalins; Biological markers

Evaluation the urine NGAL and IL-18 as early predictive markers for delayed graft function following kidney transplantation

Objective To evaluate the predictive value of urinary neutrophil gelatinase-associat-ed lipocalin (NGAL) and interleukin-18 (IL-18) for delayed graft function (DGF) in kidney transplan-tation. Methods Serial urine samples collected at 0, 12 and 24 h after operation from 86 kidney transplantation patients were analyzed by enzyme-linked immunosorbent assay for NGAL, IL-18 and RBP. Results Fifteen patients developed DGF. At 12 h after transplantation, the level of urine NGAL elevated significantly (1712.75±474.6 vs. 863.1±199.8 without DGF, P 0. 05) was not significant. At 24 h, both urine NGAL(2905.0±1108.1 vs. 911.8±221.0 without DGF,P<0. 001) and IL-18(211.3± 34.0 vs. 86.9±22.8 without DGF, P<0. 001) increased significantly, whereas the changes of urine RBP and serum creatinine (SCr) were not significant. ROC analysis showed that the area under the curve of NGAL and IL-18 were 0. 90 and 0.76 respectively, the cut-off values were 996.5 ng/mg and 148.5 ng/mg, the diagnostic sensitivities in DGF were 90.2% and 76.3%, specificities were 82.6% and 66.4% respectively. Conclusions Both urine NGAL and IL-18 could potentially be early predic-tive marker of DGF. The level of NGAL elevated earlier than IL-18, which may be more effective in predicting DGF. Key words: Kidney transplantation; Delayed graft function (DGF); Forecasting

A “Troponin” for the Kidney?

Elevated creatinine levels in patients who present to an emergency department can result from three distinct types of pathophysiology: acute renal injury (previously termed acute renal failure), preexisting renal disease, or prerenal azotemia. Distinguishing among these etiologies is difficult but important, because questions about whether to initiate treatment and which treatment is indicated are crucial. Neutrophil gelatinase–associated lipocalin (NGAL), one of several renal proteins excreted …

Oligomeric state of lipocalin-1 (LCN1) by multiangle laser light scattering and fluorescence anisotropy decay

Multiangle laser light scattering and fluorescence anisotropy decay measurements clarified the oligomeric states of native and recombinant tear lipocalin (lipocalin-1, TL). Native TL is monomeric. Recombinant TL (5–68 μM) with or without the histidine tag shows less than 7% dimer formation that is not in equilibrium with the monomeric form. Fluorescence anisotropy decay showed a correlation time of 9–10 ns for TL (10 μM–1 mM). Hydrodynamic calculations based on the crystallographic structure of a monomeric TL mutant closely concur with the observed correlation time. The solution properties calculated with HYDROPRO and SOLPRO programs from the available crystallographic structure of a monomeric TL mutant concur closely with the observed fluorescence anisotropy decay. The resulting model shows that protein topology is the major determinant of rotational correlation time and accounts for deviation from the Stokes–Einstein relation. The data challenge previous gel filtration studies to show that native TL exists predominantly as a monomer in solution rather than as a dimer. Delipidation of TL results in a formation of a complex oligomeric state (up to 25%). These findings are important as the dynamic processes in the tear film are limited by diffusional, translational as well as rotational, properties of the protein.

LCN6, a novel human epididymal lipocalin

BackgroundThe lipocalin (LCN) family of structurally conserved hydrophobic ligand binding proteins is represented in all major taxonomic groups from prokaryotes to primates. The importance of lipocalins in reproduction and the similarity to known epididymal lipocalins prompted us to characterize the novel human epididymal LCN6.Methods and ResultsLCN6 cDNA was identified by database analysis in a comprehensive human library sequencing program. Macaca mulatta (rhesus monkey) cDNA was obtained from an epididymis cDNA library and is 93% homologous to the human. The gene is located on chromosome 9q34 adjacent LCN8 and LCN5. LCN6 amino acid sequence is most closely related to LCN5, but the LCN6 beta-barrel structure is best modeled on mouse major urinary protein 1, a pheromone binding protein. Northern blot analysis of RNAs isolated from 25 human tissues revealed predominant expression of a 1.0 kb mRNA in the epididymis. No other transcript was detected except for weak expression of a larger hybridizing mRNA in urinary bladder. Northern hybridization analysis of LCN6 mRNA expression in sham-operated, castrated and testosterone replaced rhesus monkeys suggests mRNA levels are little affected 6 days after castration. Immunohistochemical staining revealed that LCN6 protein is abundant in the caput epithelium and lumen. Immunofluorescent staining of human spermatozoa shows LCN6 located on the head and tail of spermatozoa with the highest concentration of LCN6 on the post-acrosomal region of the head, where it appeared aggregated into large patches.ConclusionsLCN6 is a novel lipocalin closely related to Lcn5 and Lcn8 and these three genes are likely products of gene duplication events that predate rodent-primate divergence. Predominant expression in the epididymis and location on sperm surface are consistent with a role for LCN6 in male fertility.

Origin of Vibrio cholerae lipocalin: which gene came first?

Origin of Vibrio cholerae lipocalin: which gene came first?