Upregulation of Tubulointerstitial nephritis antigen like 1 promotes gastric cancer growth and metastasis by regulating multiple matrix metallopeptidase expression.

BACKGROUND AND AIM: Tubulointerstitial nephritis antigen-like 1 (TINAGL1), as a novel matricellular protein, has been demonstrated to participate in cancer progression, whereas the potential function of TINAGL1 in gastric cancer (GC) remains unknown. METHODS: The expression pattern of TINAGL1 in GC was examined by immunohistochemistry, ELISA, real-time polymerase chain reaction, and Western blot. Correlation between TINAGL1 and matrix metalloproteinases (MMPs) was analyzed by the GEPIA website and Kaplan-Meier plots database. The lentivirus-based TINAGL1 knockdown, CCK-8, and transwell assays were used to test the function of TINAGL1 in vitro. The role of TINAGL1 was confirmed by subcutaneous xenograft, abdominal dissemination, and lung metastasis model. Microarray experiments, ELISA, real-time polymerase chain reaction, and Western blot were used to identify molecular mechanism. RESULTS: TINAGL1 was increased in GC tumor tissues and associated with poor patient survival. Moreover, TINAGL1 significantly promoted GC cell proliferation and migration in vitro as well as facilitated GC tumor growth and metastasis in vivo. TINAGL1 expression in GC cells was accompanied with increasing MMPs including MMP2, MMP9, MMP11, MMP14, and MMP16. GEPIA database revealed that these MMPs were correlated with TINAGL1 in GC tumors and that the most highly expressed MMP was MMP2. Mechanically, TINAGL1 regulated MMP2 through the JNK signaling pathway activation. CONCLUSIONS: Our data highlight that TINAGL1 promotes GC growth and metastasis and regulates MMP2 expression, indicating that TINAGL1 may serve as a therapeutic target for GC.

Lipocalin-type prostaglandin D synthase regulates light-induced phase advance of the central circadian rhythm in mice.

We previously showed that mice lacking pituitary adenylate cyclase-activating polypeptide (PACAP) exhibit attenuated light-induced phase shift. To explore the underlying mechanisms, we performed gene expression analysis of laser capture microdissected suprachiasmatic nuclei (SCNs) and found that lipocalin-type prostaglandin (PG) D synthase (L-PGDS) is involved in the impaired response to light stimulation in the late subjective night in PACAP-deficient mice. L-PGDS-deficient mice also showed impaired light-induced phase advance, but normal phase delay and nonvisual light responses. Then, we examined the receptors involved in the response and observed that mice deficient for type 2 PGD2 receptor DP2/CRTH2 (chemoattractant receptor homologous molecule expressed on Th2 cells) show impaired light-induced phase advance. Concordant results were observed using the selective DP2/CRTH2 antagonist CAY10471. These results indicate that L-PGDS is involved in a mechanism of light-induced phase advance via DP2/CRTH2 signaling.

Lipocalin-type prostaglandin D2 synthase (L-PGDS) modulates beneficial metabolic effects of vertical sleeve gastrectomy.

BACKGROUND: Vertical sleeve gastrectomy (VSG) ameliorates metabolic complications in obese and diabetic patients through unknown mechanisms. OBJECTIVE: The objective of this study was to investigate the role of lipocalin-type prostaglandin D2 synthase (L-PGDS) in glucose regulation in response to VSG using L-PGDS knock-out (KO), knock-in (KI), and C57BL/6 (wild type) mice. SETTING: Winthrop University Hospital Research Institute. METHODS: Animals were divided into 6 groups: L-PGDS KO sham/VSG (n = 5), L-PGDS KI sham/VSG (n = 5), and C57BL/6 (wild type) sham/VSG (n = 5). Related parameters were measured in fasting animals after 10 weeks. RESULTS: Our intraperitoneal glucose tolerance tests and homeostatic model assessment insulin resistance results showed significant glycemic improvement 10 weeks post-VSG in both C57BL/6 and KI groups compared with the sham group. In contrast, the KO group developed glucose intolerance and insulin resistance similar to or greater than the sham group 10 weeks post-VSG. Interestingly, weight gain was insignificant 10 weeks post-VSG in all the groups and even trended higher in the KO group compared with sham. Peptide YY levels in the KO group post-VSG were slightly increased but significantly less than other groups. Similarly, the KO group showed significantly less leptin sensitivity in response to VSG compared with the KI group. Total cholesterol level remained unchanged in all groups irrespective of sham or surgery but interestingly, the KO group had significantly higher cholesterol levels. In parallel, adipocyte size was also found to be significantly increased in the KO group post-VSG compared with the sham group. CONCLUSION: Our findings propose that L-PGDS plays an important role in the beneficial metabolic effects observed after VSG.

Neutrophil gelatinase-associated lipocalin regulates gut microbiota of mice.

BACKGROUND AND AIM: Because neutrophil gelatinase-associated lipocalin (NGAL) is known to provide significant bacteriostatic effects during infectious conditions, we tested the hypothesis that this protein is up-regulated and secreted into the intraluminal cavity of the gut under critically ill conditions and is thus responsible for the regulation of bacterial overgrowth. METHODS: With our institutional approval, male C57BL/6J mouse (6-7 weeks) were enrolled and applied for lipopolysaccharide or peritonitis model compared with naïve control. We assessed NGAL protein concentrations in intestinal lumen and up-regulation of NGAL expression in intestinal tissues in in vivo as well as ex vivo settings. Simultaneously, we examined the effects of NGAL protein administration on the growth of Escherichia coli (E. coli) in in vivo and in vitro experimental settings. The localization of NGAL in intestinal tissues and lumen was also assessed by immunohistological approach using NGAL antibody. RESULTS: Both lipopolysaccharide and peritonitis insults evoked the marked up-regulation of NGAL mRNA and protein levels in gut tissues such as crypt cells. In addition, the administration of NGAL protein significantly inhibited the outgrowth of enteric E. coli under both in vitro and in vivo conditions, accompanied by histological evidence. CONCLUSION: Neutrophil gelatinase-associated lipocalin protein accompanied by apparent bacteriostatic action accumulated in the intestinal wall and streamed into the mucosal layer during critically ill state, thereby possibly shaping microbiota homeostasis in the gut.

STAT3-dependent reactive astrogliosis in the spinal dorsal horn underlies chronic itch.

Chronic itch is an intractable symptom of inflammatory skin diseases, such as atopic and contact dermatitis. Recent studies have revealed neuronal pathways selective for itch, but the mechanisms by which itch turns into a pathological chronic state are poorly understood. Using mouse models of atopic and contact dermatitis, we demonstrate a long-term reactive state of astrocytes in the dorsal horn of the spinal segments that corresponds to lesioned, itchy skin. We found that reactive astrogliosis depended on the activation of signal transducer and activator of transcription 3 (STAT3). Conditional disruption of astrocytic STAT3 suppressed chronic itch, and pharmacological inhibition of spinal STAT3 ameliorated the fully developed chronic itch. Mice with atopic dermatitis exhibited an increase in scratching elicited by intrathecal administration of the itch-inducer gastrin-releasing peptide (GRP), and this enhancement was normalized by suppressing STAT3-mediated reactive astrogliosis. Moreover, we identified lipocalin-2 (LCN2) as an astrocytic STAT3-dependent upregulated factor that was crucial for chronic itch, and we demonstrated that intrathecal administration of LCN2 to normal mice increased spinal GRP-evoked scratching. Our findings indicate that STAT3-dependent reactive astrocytes act as critical amplifiers of itching through a mechanism involving the enhancement of spinal itch signals by LCN2, thereby providing a previously unrecognized target for treating chronic itch.

Pathological Involvement of Astrocyte-Derived Lipocalin-2 in the Demyelinating Optic Neuritis.

PURPOSE: The current study was done to determine the role of lipocalin-2 (LCN2) in the pathogenesis of demyelinating optic neuritis using an experimental autoimmune optic neuritis (EAON) model. METHODS: The EAON was induced by subcutaneous immunization with an emulsified mixture of myelin oligodendrocyte glycoprotein (MOG35-55) peptide in mice. The LCN2 expression was examined in the optic nerve after MOG peptide injection. Degree of demyelination, inflammatory infiltration, glial activation, and expression profile of inflammatory mediators in the optic nerve were compared between LCN2 knockout (KO) animals and wild-type littermates by histological analysis and real-time PCR following EAON induction. Plasma levels of LCN2 in patients with optic neuritis were measured by ELISA. RESULTS: The expression of LCN2 was notably increased in the optic nerve after EAON induction. Expression of LCN2 was colocalized with reactive astrocytes. A significant reduction of demyelination, inflammatory infiltration, and gliosis was demonstrated in the optic nerve of LCN2 KO mice. The LCN2 KO mice also showed markedly reduced gene expression associated with the M1-polarized glia phenotype and toll-like receptor signaling in the optic nerve. The LCN2 levels in plasma were significantly higher in optic neuritis patients (71.6 ± 10.6 ng/mL) compared to healthy controls (37.4 ± 9.1 ng/mL, P = 0.0284). CONCLUSIONS: In this study, we demonstrated a significant induction of LCN2 expression in astrocytes of the optic nerve following EAON induction. Our results imply that astrocyte-derived LCN2 may have a pivotal role in the development of demyelinating optic neuritis, and LCN2 can be a therapeutic target to alleviate immune and inflammatory damage in the optic nerve.

ApoM Suppresses TNF-α-Induced Expression of ICAM-1 and VCAM-1 Through Inhibiting the Activity of NF-κB.

To explore the anti-inflammatory effect of apolipoprotein M (apoM) on regulation of tumor necrosis factor-α (TNF-α)-induced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and further investigate the molecular mechanism of apoM in this process. We found that TNF-α could decrease expression of apoM and inhibitor of NF-κB-α (IκBα) in HepG2 cells. Overexpression of apoM caused a significant decrease of ICAM-1 and VCAM-1 expression, while it caused a significant increase of IκBα expression in HepG2 cells. Furthermore, the treatment with TNF-α could increase ICAM-1 and VCAM-1 expression, decrease IκBα protein expression, and increase nuclear factor-κB (NF-κB) activity, and these effects were markedly enhanced by small interfering RNA (siRNA)-mediated silencing of apoM in HepG2 cells. Our findings demonstrated that apoM suppressed TNF-α-induced expression of ICAM-1 and VCAM-1 through inhibiting the activity of NF-κB.

Neutrophil Gelatinase-Associated Lipocalin, a Novel Mineralocorticoid Biotarget, Mediates Vascular Profibrotic Effects of Mineralocorticoids.

Activation of the mineralocorticoid receptor has been shown to be deleterious in cardiovascular diseases (CVDs). We have recently shown that lipocalin 2 (Lcn2), or neutrophil gelatinase-associated lipocalin (NGAL), is a primary target of aldosterone/mineralocorticoid receptor in the cardiovascular system. Lcn2 is a circulating protein, which binds matrix metalloproteinase 9 and modulates its stability. We hypothesized that Lcn2 could be a mediator of aldosterone/mineralocorticoid receptor profibrotic effects in the cardiovascular system. Correlations between aldosterone and profibrotic markers, such as procollagen type I N-terminal peptide, were investigated in healthy subjects and subjects with abdominal obesity. The implication of Lcn2 in the mineralocorticoid pathway was studied using Lcn2 knockout mice subjected to a nephrectomy/aldosterone/salt (NAS) challenge for 4 weeks. In human subjects, NGAL/matrix metalloproteinase 9 was positively correlated with plasma aldosterone and fibrosis biomarkers. In mice, loss of Lcn2 prevented the NAS-induced increase of plasma procollagen type I N-terminal peptide, as well as the increase of collagen fibers deposition and collagen I expression in the coronary vessels and the aorta. The lack of Lcn2 also blunted the NAS-induced increase in systolic blood pressure. Ex vivo, treatment of human fibroblasts with recombinant Lcn2 induced the expression of collagen I and the profibrotic galectin-3 and cardiotrophin-1 molecules. Our results showed that Lcn2 plays a key role in aldosterone/mineralocorticoid receptor-mediated vascular fibrosis. The clinical data indicate that this may translate in human patients. Lcn2 is, therefore, a new biotarget in cardiovascular fibrosis induced by mineralocorticoid activation.

Apolipoprotein M regulates the orphan nuclear receptor LRH-1 gene expression through binding to its promoter region in HepG2 cells.

Apolipoprotein M (ApoM) is predominantly located in the high-density lipoprotein in human plasma. It has been demonstrated that ApoM expression could be regulated by several crucial nuclear receptors that are involved in the bile acid metabolism. In the present study, by combining gene-silencing experiments, overexpression studies, and chromatin immunoprecipitation assays, we showed that ApoM positively regulated liver receptor homolog-1 (LRH-1) gene expression via direct binding to an LRH-1 promoter region (nucleotides -406/ -197). In addition, we investigated the effects of farnesoid X receptor agonist GW4064 on hepatic ApoM expression in vitro. In HepG2 cell cultures, both mRNA and protein levels of ApoM and LRH-1 were decreased in a time-dependent manner in the presence of 1 µM GW4064, and the inhibition effect was gradually attenuated after 24 hours. In conclusion, our findings present supportive evidence that ApoM is a regulator of human LRH-1 transcription, and further reveal the importance of ApoM as a critical regulator of bile acids metabolism.

Role of Lipocalin-type prostaglandin D2 synthase (L-PGDS) and its metabolite, prostaglandin D2, in preterm birth.

The objective of the study was to investigate the role of prostaglandin D2 during pregnancy and its mediator Lipocalin-type prostaglandin D2 synthase (L-PGDS) as a predictor of preterm birth (PTB). Transgenic L-PGDS (+/+), L-PGDS (-/-) and C57BL/6 control pregnant mice models were used to determine the effect of DP1 and DP2 receptor antagonists in lipopolysaccharide (LPS)-induced PTB mice. In addition, L-PGDS levels were measured in the cervicovaginal secretions (CVS) of 370 pregnant women using ELISA and further processed for isoform detection using 2-D gel electrophoresis. Our results found that C57BL/6 control mice (n = 26), transgenic L-PGDS (+/+) (n = 26), demonstrated an 89% and 100% preterm birth in LPS (intraperitoneal injection, 20mg/kg) induced mice model respectively. Interestingly, the incidence of PTB was significantly reduced to 40% in L-PGDS (-/-) knockout mice (n = 26). DP1 and DP2 receptor antagonists (0.264 µg/day, dose of 0.1 µg/µl with the flow of 0.11 µl/h for 28 day using Alzet pumps) were used to investigate the effect in LPS-induced PTB in C57BL/6 mice and found 3.3-fold increase in viable pups after LPS-induction. In addition, L-PGDS levels were measured in CVS samples and found that PTB women (n = 296) had two-fold higher levels compared to full term births (n = 74) and established a significant inverse correlation between levels of L-PGDS and days to expected delivery by using 370 preterm birth CVS samples. Elevated L-PGDS levels in the CVS of women may be considered as a potential biomarker for PTB in future. Secondly, the use of DP1 and DP2 receptor antagonists may represent novel tocolytic agents for the treatment of PTB.

A possible contribution of lipocalin-2 to the development of dermal fibrosis, pulmonary vascular involvement and renal dysfunction in systemic sclerosis.

BACKGROUND: Lipocalin-2 is an adipocytokine implicated in apoptosis, innate immunity, angiogenesis, and the development of chronic kidney disease. OBJECTIVES: To investigate the role of lipocalin-2 in systemic sclerosis (SSc). MATERIALS AND METHODS: Serum lipocalin-2 levels were determined by enzyme-linked immunosorbent assay in 50 patients with SSc and 19 healthy subjects. Lipocalin-2 expression was evaluated in the skin of patients with SSc and bleomycin (BLM)-treated mice and in Fli1-deficient endothelial cells by reverse transcriptase-real time polymerase chain reaction, immunoblotting and/or immunohistochemistry. RESULTS: Although serum lipocalin-2 levels were comparable between patients with SSc and healthy controls, the prevalence of scleroderma renal crisis was significantly higher in patients with SSc with elevated serum lipocalin-2 levels than in those with normal levels. Furthermore, serum lipocalin-2 levels inversely correlated with estimated glomerular filtration rate in patients with SSc with renal dysfunction. Among patients with SSc with normal renal function, serum lipocalin-2 levels positively correlated with skin score in patients with diffuse cutaneous SSc with disease duration of < 3 years and inversely correlated with estimated right ventricular systolic pressure in total patients with SSc. Importantly, in SSc lesional skin, lipocalin-2 expression was increased in dermal fibroblasts and endothelial cells. In BLM-treated mice, lipocalin-2 was highly expressed in dermal fibroblasts, but not in endothelial cells. On the other hand, the deficiency of transcription factor Fli1, which is implicated in SSc vasculopathy, induced lipocalin-2 expression in cultivated endothelial cells. CONCLUSIONS: Lipocalin-2 may be involved in renal dysfunction and dermal fibrosis of SSc. Dysregulated matrix metalloproteinase-9/lipocalin-2-dependent angiogenesis due to Fli1 deficiency may contribute to the development of pulmonary arterial hypertension associated with SSc.

L-Arginine attenuates the ethylene glycol induced urolithiasis in ininephrectomized hypertensive rats: role of KIM-1, NGAL, and NOs.

BACKGROUND: Ethylene glycol (EG) exposure caused formation of calcium oxalate crystal that led to renal failure, which is associated with higher prevalence of hypertension. L-Arginine is known to have an antioxidant and nephro-protective potential. OBJECTIVE: To evaluate the effect of L-arginine against EG-induced urolithiasis in uninephrectomized hypertensive rats. MATERIAL AND METHODS: Uninephrectomized male Wistar rats (180-200 g) were used to induce urinary calculi through oral administration of EG (0.75%) in distilled water. Rats were treated with either distilled water (10 mg/kg, p.o.) or telmisartan (10 mg/kg, p.o.) or Cystone (500 mg/kg, p.o.) or L-arginine (250, 500, and 1000 mg/kg, p.o.) for 28 days. Various hemodynamic, biochemical, molecular, and histological parameters were assessed in kidney and heart. RESULTS: Rats treated with L-arginine (500 and 1000 mg/kg) significantly restored altered relative organ weight, urine output, urine density, urinary pH, and water intake. EG-induced alterations in electrocardiographic (QRS interval, HR, and ST height) and hemodynamic (SBP, DBP, MABP, and LVEDP) abnormalities were significantly restored by L-arginine (500 and 1000 mg/kg) treatment. It also significantly restored alteration in serum and urine biochemical parameters induced by EG. The elevated oxido-nitrosative stress was also significantly decreased by L-arginine (500 and 1000 mg/kg) treatment. It also significantly down-regulated EG-induced up-regulated renal KIM-1, NGAL, eNOS, and iNOs mRNA expressions. Histological aberrations induced in the renal and cardiac tissues were also ameliorated by l-arginine treatment. CONCLUSION: L-Arginine exerts its nephro- and cardio-protective potential in EG-induced urolithiasis in uninephrectomized hypertensive rats via modulation of KIM-1, NGAL, eNOS, and iNOs mRNA expression.

Dexamethasone protects neonatal hypoxic-ischemic brain injury via L-PGDS-dependent PGD2-DP1-pERK signaling pathway.

BACKGROUND AND PURPOSE: Glucocorticoids pretreatment confers protection against neonatal hypoxic-ischemic (HI) brain injury. However, the molecular mechanism remains poorly elucidated. We tested the hypothesis that glucocorticoids protect against HI brain injury in neonatal rat by stimulation of lipocalin-type prostaglandin D synthase (L-PGDS)-induced prostaglandin D2 (PGD2)-DP1-pERK mediated signaling pathway. METHODS: Dexamethasone and inhibitors were administered via intracerebroventricular (i.c.v) injections into 10-day-old rat brains. Levels of L-PGD2, D prostanoid (DP1) receptor, pERK1/2 and PGD2 were determined by Western immunoblotting and ELISA, respectively. Brain injury was evaluated 48 hours after conduction of HI in 10-day-old rat pups. RESULTS: Dexamethasone pretreatment significantly upregulated L-PGDS expression and the biosynthesis of PGD2. Dexamethasone also selectively increased isoform pERK-44 level in the neonatal rat brains. Inhibitors of L-PGDS (SeCl4), DP1 (MK-0524) and MAPK (PD98059) abrogated dexamethasone-induced increases in pERK-44 level, respectively. Of importance, these inhibitors also blocked dexamethasone-mediated neuroprotective effects against HI brain injury in neonatal rat brains. CONCLUSION: Interaction of glucocorticoids-GR signaling and L-PGDS-PGD2-DP1-pERK mediated pathway underlies the neuroprotective effects of dexamethasone pretreatment in neonatal HI brain injury.

Diagnostic and prognostic utility of neutrophil gelatinase-associated lipocalin (NGAL) in patients with cardiovascular diseases--review.

NGAL (neutrophil gelatinase-associated lipocalin) is an acute phase protein, participating in antibacterial immunity. NGAL forms a complex with metalloproteinase 9 (MMP-9), thereby increasing its activity and preventing its degradation. NGAL is freely filtered through the glomerular membrane and reabsorbed by endocytosis in the proximal tubule. NGAL detected in urine is produced mainly in the distal nephron. Elevated serum and urine NGAL allows diagnosis of acute kidney injury approximately 24 hours earlier than plasma creatinine concentration. Increased levels of NGAL were detected in patients with acute myocardial infarction, heart failure or stroke and were demonstrated to be strong predictors of adverse prognosis.

Up-regulated lipocalin-2 in pulmonary hypertension involving in pulmonary artery SMC resistance to apoptosis.

A key feature of pulmonary hypertension (PH) is the remodeling of small pulmonary arteries due to abnormal pulmonary artery smooth muscle cell (PASMC) proliferation and resistance to apoptosis. However, the cellular mechanisms underlying how PASMCs in the pathological condition of pulmonary hypertension become resistant to apoptosis remain unknown. It was recently reported that lipocalin 2 (Lcn2) is up-regulated in a wide array of malignant conditions, which facilitates tumorigenesis partly by inhibiting cell apoptosis. In this study, we observed that the expression levels of Lcn2 were significantly elevated in a rat PH model induced with monocrotaline and in patients with congenital heart disease-associated PH (CHD-PH) when compared with respective control. Therefore, we hypothesize that Lcn2 could regulate human PASMC (HPASMC) apoptosis through a mechanism. By the detection of DNA fragmentation using the TUNEL assay, the detection of Annexin V/PI-positive cells using flow cytometry, and the detection of cleaved caspase-3 and caspase-3 activity, we observed that Lcn2 significantly inhibited HPASMC apoptosis induced by serum withdrawal and H2O2 treatment. We also observed that Lcn2 down-regulated the proapoptotic protein Bax, decreased the levels of cellular ROS, and up-regulated the expression of superoxide dismutases (SOD1 and SOD2). In conclusion, Lcn2 significantly inhibits HPASMC apoptosis induced by oxidative stress via decreased intracellular ROS and elevated SODs. Up-regulation of Lcn2 in a rat PH model and CHD-PH patients may be involved in the pathological process of PH.

Recombinant human erythropoietin pretreatment attenuates acute renal tubular injury against ischemia-reperfusion by restoring transient receptor potential channel-6 expression and function in collecting ducts.

OBJECTIVE: Acute renal tubular injury is a serious complication in the postoperative period, which is associated with high mortality and increased ICU stay. We aimed to demonstrate the protective effect of rhEPO against acute tubular injury induced by ischemia-reperfusion and to explore the mechanism of canonical transient receptor potential channel-6. DESIGN: Randomized laboratory animal study. SETTINGS: Animal research laboratory. INTERVENTIONS: Male Sprague-Dawley rats were randomly divided into three groups: the sham group, the control group, and the rhEPO group. Experimental acute tubular injury was established in rats by bilateral renal arterial occlusion for 30 minutes followed by reperfusion. MEASUREMENTS AND MAIN RESULTS: Blood samples were obtained for cystatin-C and neutrophil gelatinase-associated lipocalin measurements by enzyme-linked immunosorbance assays. Seventy-two hours after reperfusion, urine samples were collected for osmolality and fractional excretion of sodium (%) assays on a chemistry analyzer. Kidneys were harvested at 24, 48, and 72 hours after reperfusion. Transient receptor potential channel-6, aquaporin-2, and Na,K-ATPase expression in collecting ducts were studied by immunofluorescence and Western blot. Coimmunoprecipitations were also performed to identify the possible signalplex relation between transient receptor potential channel-6 and aquaporin-2 or Na,K-ATPase channels. RhEPO pretreatment significantly inhibited serum cystatin-C (2 hr: 453 ± 64 µg/L vs 337 ± 28 µg/L, p < 0.01), serum neutrophil gelatinase-associated lipocalin (72 hr: 1,175 ± 107 ng/L vs 1,737 ± 402 ng/L, p < 0.05), and urinary fractional excretion of sodium (%) increase (0.9 ± 0.1 vs 2.2 ± 0.8, p < 0.05) and alleviated the decrease of urinary osmolality (1,293 ± 101 mosmol/kg H2O vs 767 ± 91 mosmol/kg H2O, p < 0.05) induced by ischemia-reperfusion injury. Meanwhile, recombinant human erythropoietin greatly improved the ischemia-reperfusion-induced attenuation of transient receptor potential channel-6 expression (48 hr: 42% ± 2% vs 67% ± 2% and 72 hr: 55% ± 2% vs 66% ± 2%), as well as aquaporin-2 and Na,K-ATPase expression in collecting ducts. Transient receptor potential channel-6 functionally interacted with Na,K-ATPase but not aquaporin-2. CONCLUSIONS: Recombinant human erythropoietin pretreatment at the dose of 5,000 IU/kg potently prevented ischemia-reperfusion-induced acute tubular injury, which might be partly attributed to the restoring the effect of transient receptor potential channel-6 expression and collecting duct function.

Neutrophil gelatinase-associated lipocalin in cancer.

Neutrophil gelatinase-associated lipocalin (NGAL), also known as lipocalin-2, is a 178-amino acid protein which exists in three molecular forms, including a 25-kDa monomer, a 45-kDa homodimer, and a 135-kDa heterodimer complexed with matrix metalloproteinase 9 (MMP-9). Polymorphonuclear neutrophils and tubular cells of the kidney are the most representative cellular sources. As such, NGAL is now considered the biochemical gold standard for early diagnosis of acute kidney injury. Recent evidence suggests, however, that ectopic or enhanced expression of NGAL may occur in many other pathologic conditions including cancer. Several epidemiologic studies, as reviewed in this chapter, showed that a variety of malignant tumors consistently overexpressed NGAL with increased concentration in blood, urine, and other biologic fluids. In addition, NGAL was frequently associated with tumor size, stage, and invasiveness. These features thus make it a potential biomarker for malignancy. A number of experimental studies also demonstrated that the ability to bind MMP-9, to scavenge iron into cancer cells along with the effect on subcellular localization of transmembrane proteins such as cadherins and catenins, confers this protein the potential to enhance can cer aggressiveness and makes it an appealing target of future anticancer research.

Acute white matter injury after experimental subarachnoid hemorrhage: potential role of lipocalin 2.

BACKGROUND AND PURPOSE: White matter injury occurs after subarachnoid hemorrhage (SAH) and has not been well studied. In this study, we investigated acute white matter injury in a mouse SAH model and the role of lipocalin 2 (LCN2) in that injury. METHODS: SAH was induced by endovascular perforation in wild-type (WT) or LCN2 knockout (LCN2-/-) mice. Sham WT mice underwent the same procedure without perforation. MRI was performed 24 hours after SAH and the volumes of the T2-hyperintensity in white matter were measured. Immunohistochemistry was performed to determine white matter injury. RESULTS: Mortality rates and SAH severity were not significantly different between WT and LCN2-/- animals. T2-hyperintensity in the white matter was observed in all WT animals at 24 hours after SAH (6.1±2.7 versus 0.06±0.07 mm3 in sham; P<0.001), and the volume of T2-hyperintensity tended to correlate with SAH severity (r=0.30; P=0.055). In WT animals with SAH, numerous LCN2-positive cells were observed in white matter. In contrast, LCN2-/- animals scarcely developed white matter T2-hyperintensity after SAH (0.5±0.5 mm3; P<0.001, versus WT). Markers of axonal damage and myelin degradation were increased in white matter after SAH in WT compared with those in LCN2-/- animals (P<0.05). CONCLUSIONS: SAH results in an acute white matter injury at 24 hours in mice, and LCN2 plays an important role in SAH-induced white matter injury.