Neutrophil Gelatinase-associated Lipocalin Protein Expression Research Articles

Novel anti-inflammatory effects of the IL-1 receptor in kidney myeloid cells following ischemic AKI.

Introduction: Acute kidney injury (AKI) is one of the most common causes of organ failure in critically ill patients. Following AKI, the canonical pro-inflammatory cytokine interleukin-1β (IL-1β) is released predominantly from activated myeloid cells and binds to the interleukin-1 receptor R1 (IL-1R1) on leukocytes and kidney parenchymal cells. IL-1R1 on kidney tubular cells is known to amplify the immune response and exacerbate AKI. However, the specific role of IL-1R1 on myeloid cells during AKI is poorly understood. The objective of the present study was to elucidate the function of myeloid cell IL-1R1 during AKI. As IL-1R1 is known to signal through the pro-inflammatory Toll-like receptor (TLR)/MyD88 pathway, we hypothesized that myeloid cells expressing IL-1R1 would exacerbate AKI. Methods: IL-1R1 was selectively depleted in CD11c+-expressing myeloid cells with CD11cCre + /IL-1R1 fl/fl (Myel KO) mice. Myel KO and littermate controls (CD11cCre - /IL-1R1 fl/fl-Myel WT) were subjected to kidney ischemia/reperfusion (I/R) injury. Kidney injury was assessed by blood urea nitrogen (BUN), serum creatinine and injury marker neutrophil gelatinase-associated lipocalin (NGAL) protein expression. Renal tubular cells (RTC) were co-cultured with CD11c+ bone marrow-derived dendritic cells (BMDC) from Myel KO and Myel WT mice. Results: Surprisingly, compared to Myel WT mice, Myel KO mice displayed exaggerated I/R-induced kidney injury, as measured by elevated levels of serum creatinine and BUN, and kidney NGAL protein expression. In support of these findings, in vitro co-culture studies showed that RTC co-cultured with Myel KO BMDC (in the presence of IL-1β) exhibited higher mRNA levels of the kidney injury marker NGAL than those co-cultured with Myel WT BMDC. In addition, we observed that IL-1R1 on Myel WT BMDC preferentially augmented the expression of anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1ra/Il1rn), effects that were largely abrogated in Myel KO BMDC. Furthermore, recombinant IL-1Ra could rescue IL-1β-induced tubular cell injury. Discussion: Our findings suggest a novel function of IL-1R1 is to serve as a critical negative feedback regulator of IL-1 signaling in CD11c+ myeloid cells to dampen inflammation to limit AKI. Our results lend further support for cell-specific, as opposed to global, targeting of immunomodulatory agents.

Obesity Exacerbates Lipid Nephrotoxicity and Renal Injury in a Model of Ovarian Hormone Deficiency

Obesity rates are continually increasing both in the USA and around the world. As rates of obesity continue to grow, public health concerns remain a top priority in order to curtail mortality and morbidity. An increase in visceral adipose tissue is correlated with dysfunction in multiple organs, including the kidneys. Increases in basal metabolic index, or BMI, has been linked to increases in triglyceride accumulation in the kidneys. Obesity accounts for ~25% of kidney diseases observed in women; however, its effects on kidney function have not been defined in post‐menopausal women. In an ovarian hormone deficient mouse model (ovariectomized animals), we measured a significant weight gain compared with sham‐operated control, associated with perirenal adipose tissue accumulation, and an increase in 1. glomerular filtration rate (GFR) used to determine renal function, 2. protein level of the NGAL, an early biomarker of kidney injury and 3. intrarenal lipid accumulation found in the renal tubules. In this study, we aim to determine whether obesity affects the levels of renal injury and lipid accumulation measured in a model of ovarian hormone deficiency. We studied four groups of mice: the first and second groups underwent ovariectomy (OVX); group one was fed a 60% high‐fat (HF) diet, and group two was on a 10% low‐fat (LH) diet. The third and fourth groups (controls), underwent surgery without ovariectomy (SHAM) and were fed a HF or LF diet. All animals had ad libitum access to their respective diet for fourteen weeks (i.e., ten weeks prior to surgery and four weeks after). Significant increase in body weight was measured in mice on HF compared to LF diet. The size of triglyceride droplets in the renal tubules was significantly higher (20‐25%) in OVX compared to SHAM‐operated control mice on both HF and LF diets. The Neutrophil Gelatinase Associated Lipocalin (NGAL) protein levels were measured as a biomarker of kidney injury. Levels of NGAL protein expression increased in OVX mice when compared to SHAM control in the renal tubules of mice on both HF (211.3 ± 3.7%, p<0.0001) and LF diet (111.33 ± 1.7%, p=0.02). In the glomeruli, NGAL protein expression levels increased in OVX mice compared to SHAM control in HF (188.8 ± 9.9%, p<0.0001) and LF diet fed groups (113.1 ± 4.9%, p=0.64). Furthermore, mice on HF diet had significant higher NGAL levels in OVX and sham‐control conditions than mice in the same conditions on LF diet. These findings indicate that weight gain exacerbates renal injury induced by OVX, and that estrogen may be protective against excessive accumulation of triglycerides in kidney structures. Our study supports the understanding of the mechanisms implicated in the development of kidney diseases in obese post‐menopausal women.

NGAL protects in nasopharyngeal carcinoma by inducing apoptosis and blocking epithelial-mesenchymal transition.

In recent years, neutrophil gelatinase-associated lipocalin (NGAL) has been considered to be a key molecule in different cancer types and its carcinogenesis may be related to the NGAL/MMP-9 complex. However, its expression pattern and role in nasopharyngeal carcinoma (NPC) has rarely been reported. In the current study, 158 tumor tissues from NPC patients were collected and immunohistochemistry was performed to determine the NGAL protein expression, to investigate the correlation between its expression and clinical and pathological parameters using Chi square analysis. Furthermore, by over-expressing NGAL in NPC cell lines, biological alteration of NPC cells with respect to cell proliferation, migration and invasion was analyzed. Results suggested that high expression of NGAL predicts better prognosis and longer survival. Overexpression of NGAL significantly reduced the proliferation and migration of NPC cells, and induced the apoptosis by activating caspase 3, 8 and 9, and blocking epithelial-mesenchymal transition by inhibiting mothers against decapentaplegic homolog 2/3 phosphorylation.

Ascorbic acid ameliorates renal injury in a murine model of contrast-induced nephropathy

BackgroundContrast induced nephropathy (CIN) is the commonest cause of iatrogenic renal injury and its incidence has increased with the advent of complex endovascular procedures. Evidence suggests that ascorbic acid (AA) has a nephroprotective effect in percutaneous coronary interventions when contrast media are used. A variety of biomarkers (NGAL, NGAL:creatinine, mononuclear cell infiltration, apoptosis and RBP-4) in both the urine and kidney were assayed using a mouse model of CIN in order to determine whether AA can reduce the incidence and/or severity of renal injury.MethodsTwenty-four BALB/c mice were divided into 4 groups. Three groups were exposed to high doses of contrast media (omnipaque) in a well-established model of CIN, and then treated with low or high dose AA or placebo (saline). CIN severity was determined by measurement of urinary neutrophil gelatinase-associated lipocalin (NGAL):creatinine at specific time intervals. Histological analysis was performed to determine the level of mononuclear inflammatory infiltration as well as immunohistochemistry to determine apoptosis in the glomeruli by staining for activated caspase-3 and DNA nicking (TUNEL assays). Reverse transcriptase PCR (rtPCR) of mRNA transcripts prepared from mRNA extracted from mouse kidneys was also performed for both lipocalin-2 (Lcn2) encoding NGAL and retinol binding protein-6 (RBP4) genes. NGAL protein expression was also confirmed by ELISA analysis of kidney lysates.ResultsUrinary NGAL:creatinine ratio was significantly lower at 48 h with a 44% and 62% (204.3μg/mmol versus 533.6μg/mmol, p = 0.049) reduction in the low and high dose AA groups, respectively. The reduced urinary NGAL:creatinine ratio remained low throughout the time period assessed (up to 96 h) in the high dose AA group. In support of the urinary analysis ELISA analysis of NGAL in kidney lysates also showed a 57% reduction (12,576 ng/ml versus 29,393 ng/ml) reduction in the low dose AA group. Immunohistochemistry for apoptosis demonstrated decreased TUNEL and caspase-3 expression in both low and high dose AA groups.ConclusionsAscorbic acid reduced the frequency and severity of renal injury in this murine model of CIN. Further work is required to establish whether AA can reduce the incidence of CIN in humans undergoing endovascular procedures.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) is Associated with Symptomatic Carotid Atherosclerosis and Drives Pro-inflammatory State In Vitro

Neutrophil gelatinase-associated lipocalin (NGAL), a protein found in activated neutrophils, is expressed in kidney tubule cells in response to noxious stimuli, and is thus recognized as a marker of acute kidney injury. Recent studies have suggested that NGAL could also have pathophysiological importance in cardiovascular diseases. The aim of the present study was to examine NGAL expression in human carotid endarterectomy tissues ex vivo as well as the effects of NGAL in the main cell types involved in atherogenesis, namely in human macrophages, endothelial cells, and smooth muscle cells in vitro. NGAL protein was analyzed in human endarterectomy samples from patients with asymptomatic and symptomatic carotid stenosis by immunofluorescence, and NGAL mRNA expression was detected using RealTime-PCR. Human monocyte derived macrophages (MDM), human coronary artery smooth muscle cells (HCASMC), and human umbilical vein endothelial cells (HUVEC) were treated with recombinant human (rh) NGAL at different concentrations. Interleukin (IL)-6, IL-8, and monocyte chemo-attractant protein-1 (MCP-1) were determined by specific enzyme linked immunosorbent assays (ELISAs) in culture supernatants of such treated cells. Expression of NGAL protein was demonstrated by macrophages, smooth muscle cells, and endothelial cells in human carotid atherosclerotic tissue. NGAL mRNA expression was detected at a higher rate in atherosclerotic tissue of patients with symptomatic carotid stenosis (in 70%; n = 19) compared with asymptomatic patients (in 37%; n = 20, P < .001). Treatment of MDM, HCASMC, and HUVEC with rhNGAL led to a significant (P < .05) and concentration dependent increase of pro-inflammatory cytokines IL-6, IL-8, and MCP-1 in all cell types analyzed. By induction of pro-inflammatory mediators in human macrophages, smooth muscle cells and endothelial cells, NGAL, which is predominantly expressed in atherosclerotic plaques of symptomatic patients, could be involved in creating the local and systemic pro-inflammatory environment characteristic for atherosclerosis.

0226 : Neutrophil gelatinase – associated lipocalin mediates the profibrotic effects of aldosterone in human cardiac fibroblasts

Aldosterone (Aldo) through Mineralcorticoid Receptor (MR) plays an important pathophysiological role in cardiovascular remodeling and diseases. Cardiac remodeling is characterized by changes in the extracellular matrix (ECM), which favors the development of myocardial fibrosis, and finally could compromises cardiac function and contributes to heart failure. Neutrophil gelatinase-associated lipocalin (NGAL) is a primary target of Aldosterone (Aldo)/MR in the cardiovascular system. However, the role of NGAL in cardiac remodeling is still unclear. We investigated the effects of NGAL on the production of ECM components in human cardiac fibroblasts (HCF) and whether NGAL could be a mediator of Aldo-induced ECM components in HCF. Collagen I protein levels were measured in response to Aldo (10- 10-10-8M) and NGAL (5-500 ng/ml) in HCF for 12-24 hours. Protein and gene expression of different profibrotic mediators such as galectin-3 (Gal-3), cardiotrophin-1 (CT-1), transforming growth factor-beta (TGF-β) and metalloproteinase (MMP) activities were studied in response to NGAL and Aldo. Finally, in order to study the role of NGAL on the profibrotic actions of Aldo, NGAL-silenced HCF were treated with Aldo In HCF, Aldo and NGAL increased collagen I protein expression in a dose-dependent manner, reaching maximal values at 24 hours. At this time, Aldo increased NGAL protein expression. NGAL and Aldo enhanced profibrotic mediators such as Gal-3, CT-1 and TGF-β, as well as MMP-1, MMP-2 and MMP-9 activities. In NGAL silenced cells, Aldo was not able to modify collagen I expression as well as fibronectin, galectin-3, cardiotrophin- 1 and TGF-β levels. Our results indicated that NGAL exerts profibrotic effects in HCF. Furthermore, NGAL emerges as a potential mediator of Aldo-induced cardiac fibrosis and could be consider as a biotarget for novel pharmacological approaches, especially in diseases where Aldo/MR pathway is involved. The author hereby declares no conflict of interest

Neutrophil Gelatinase-Associated Lipocalin (NGAL) is Associated with Symptomatic Carotid Atherosclerosis and Drives Pro-inflammatory State In Vitro

Neutrophil gelatinase-associated lipocalin (NGAL), a protein found in activated neutrophils, is expressed in kidney tubule cells in response to noxious stimuli, and is thus recognized as a marker of acute kidney injury. Recent studies have suggested that NGAL could also have pathophysiological importance in cardiovascular diseases. The aim of the present study was to examine NGAL expression in human carotid endarterectomy tissues exvivo as well as the effects of NGAL in the main cell types involved in atherogenesis, namely in human macrophages, endothelial cells, and smooth muscle cells invitro. NGAL protein was analyzed in human endarterectomy samples from patients with asymptomatic and symptomatic carotid stenosis by immunofluorescence, and NGAL mRNA expression was detected using RealTime-PCR. Human monocyte derived macrophages (MDM), human coronary artery smooth muscle cells (HCASMC), and human umbilical vein endothelial cells (HUVEC) were treated with recombinant human (rh) NGAL at different concentrations. Interleukin (IL)-6, IL-8, and monocyte chemo-attractant protein-1 (MCP-1) were determined by specific enzyme linked immunosorbent assays (ELISAs) in culture supernatants of such treated cells. Expression of NGAL protein was demonstrated by macrophages, smooth muscle cells, and endothelial cells in human carotid atherosclerotic tissue. NGAL mRNA expression was detected at a higher rate in atherosclerotic tissue of patients with symptomatic carotid stenosis (in 70%; n=19) compared with asymptomatic patients (in 37%; n=20, p<.001). Treatment of MDM, HCASMC, and HUVEC with rhNGAL led to a significant (p<0.05) and concentration dependent increase of pro-inflammatory cytokines IL-6, IL-8, and MCP-1 in all cell types analyzed. By induction of pro-inflammatory mediators in human macrophages, smooth muscle cells and endothelial cells, NGAL, which is predominantly expressed in atherosclerotic plaques of symptomatic patients, could be involved in creating the local and systemic pro-inflammatory environment characteristic for atherosclerosis.

High expression of neutrophil gelatinase-associated lipocalin (NGAL) in the kidney proximal tubules of diabetic rats

PurposeRecent evidence suggests that neutrophil gelatinase-associated lipocalin (NGAL) plays important roles in many physiological and pathological processes including diabetic nephropathy (DN), in which a markedly increasing in NGAL levels in patient's serum and urine has been reported. This study investigated the expression of NGAL in the kidney of diabetic rats. Materials/methodsSixty-four Sprague Dawley rats were randomly divided into 2 groups: non-diabetic control groups and diabetic groups. Diabetes was induced by intraperitoneal injection of streptozotocin. Relevant indicators were separately evaluated 2, 4, 8 and 12 weeks after induction of diabetes. ResultsIn the diabetic groups, urinary NGAL values were markedly increased even before the appearance of pathological albuminuria. Moreover, diabetic rats showed significant upregulation of NGAL mRNA expression starting at week 2 (1.0±0.03 vs. 3.09±0.40, NGAL/β-actin, P<0.05), while the increase of NGAL protein expression appeared subsequently (0.58±0.03 vs. 0.65±0.01, NGAL/β-actin, P<0.05). At the end of week 12, kidney NGAL mRNA and protein levels were increased to 5.95-fold and 1.24-fold of the control groups, respectively. Observable ultrastructural alterations of renal tubules were not detected until week 4, while pathological changes gradually became apparent in the course of the study. Strong positive immunohistochemical staining of NGAL was visualized in the proximal tubular cells of diabetic rats at week 12. ConclusionsHigh expression of NGAL in the kidney is associated with diabetic kidney injury in STZ rats, suggesting NGAL may play a role in tubular injury of DN.

Effect of Cordyceps sinensis on the expression of HIF-1α and NGAL in rats with renal ischemia-reperfusion injury

To observe the level of urinary neutrophil gelatinase-associated lipocalin (NGAL), the expression of hypoxia inducible factor-1α (HIF-1α) and NGAL in rat kidney after renal ischemia and reperfusion (I/R), before and after the treatment with Cordyceps Sinensis (C. sinensis), and to explore the mechanism of C. sinensis against I/R injury. A total of 45 healthy male Sprague-Dawley rats were randomly divided into a sham group, a renal I/R model group, and a C. sinensis group (15 in each group).The rats in the sham group and the renal I/R model group were intragastrically administered saline (2 mL/d), and rats in the treatment group were intragastricabby administered of C. sinensis [5.0 g/(kg.d)]. The rats were sacrificed at 24, 48, and 72 h, respectively after the reperfusion and urinary N-acetyl-β-D-glucosaminidase (NAG) level was measured, renal function in rats was detected, and the pathological changes were observed with HE staining. We determined the urinary NGAL levels in the rats by ELISA, the expression of HIF-1α mRNA by RT-PCR, and the expressions of HIF-1α and NGAL proteins by confocal immunofluorescence. Compared with the sham group, the levels of BUN, SCr, levels of NAG and NGAL in urine were increased in the I/R group and the C. sinensis group, reached a peak at 24 h after the reperfusion and slowly declined at 48 and 72 h. Glomerular and tubulointerstitial areas in the sham group did not show any pathological change. Induced pathological changes included tubular cell necrosis, focal areas of proximal tubular dilation, distal tubular casts, effacement and loss of proximal tubule brush border, etc. Compared with the sham group, the expression of HIF-1α and NGAL in the kidney tissues of the I/R group and the C. sinensis group increased. C. sinensis can lower the level of NAG and NGAL in the urine and the expression of NGAL protein in the kidney tissues. It up-regulated the expression of HIF-1α mRNA and protein in the kidney tissues whilst attenuated the pathological changes. Renal I/R injury in rats can lead to pathological changes in renal tubular epithelial cells and renal interstitial damage, which are consistent with the pathological features of acute kidney injury (AKI).The level of urinary NAGL increases after the I/R, and positively correlates with the level of urinary NAG and pathological changes, suggesting that urinary NGAL may serve as a urinary biomarker for specific detection of tubular injury in AKI. C. sinensis can attenuate the renal I/ R-induced AKI. Its mechanism may be associated with up-regulating the expression of HIF-1α and down-regulating the expression of NGAL in the kidney tissues.

749: The impact of obesity on the disease course of preeclampsia

disease course of preeclampsia Emily Miller, Alan Peaceman Northwestern University, Maternal Fetal Medicine, Chicago, IL OBJECTIVE: Obesity is a well-established risk factor for the development of preeclampsia. Various possible causal etiologies have been proposed to explain this relationship. Insofar as these pathways toward preeclampsia may differ from the pathophysiology of preeclampsia in non-obese parturients, the clinical ramifications of the disease may differ. This study was designed to assess whether there is a difference in the clinical presentation of preeclampsia between obese and non-obese women. STUDY DESIGN: This is a retrospective cohort study of women who received a diagnosis of pre-eclampsia. Women were categorized as obese (pre-pregnancy BMI 30.0 kg/m2) or non-obese (pre-pregnancy BMI 30.0 kg/m2). Clinical data pertaining to their preeclampsia were abstracted from the chart, including gestational age at delivery, neonatal birth weight, blood pressure ranges, and lab values (creatinine, liver function tests, uric acid, platelet count, level of proteinuria). RESULTS: Of the 874 women included, 531 (61%) were obese. There were no statistically significant differences in maternal age, gestational age at delivery, BUN or creatinine levels, or amount of proteinuria between the two groups. While there was no difference in highest systolic blood pressure recorded, the non-obese cohort had a higher median maximum diastolic blood pressure [101 mm Hg (IQR 94107) v 98 mm Hg (IQR 92-104), p 0.001]. In addition, the non-obese group had a significantly increased risk of having an elevated AST (47% vs 32%, p 0.001), an elevated ALT (25% vs 18%, p 0.014), and thrombocytopenia (45% vs 30%). The non-obese women were twice as likely to develop both a platelet count of less than 100,000 and LFTs more than double of normal, consistent with the diagnosis of HELLP syndrome (6.7% v 2.8%, p 0.006). CONCLUSION: Of the women that were identified with preeclampsia, the majority were obese. However women with obesity and preeclampsia had lab abnormalities less frequently and also lower peak diastolic blood pressures. This suggests that the pathophysiology of preeclampsia may differ between obese and non-obese women. 750 Preeclampsia (PE) enhances NGAL expression at fetal-maternal interface: role of iron and hypoxia Errol Norwitz, Serkalem Tadesse, Zhonghua Tang, Seth Guller Tufts University School of Medicine, Obstetrics & Gynecology, Boston, MA, Tufts Medical Center, Obstetrics & Gynecology, Division of Maternal-Fetal Medicine, Boston, MA, Yale University School of Medicine, Obstetrics, Gynecology and Reproductive Sciences, New Haven, CT OBJECTIVE: PE is associated with both a substantial elevation in iron deposition and an aberrant maintenance of hypoxia at the maternalfetal interface. Indeed, increases in serum iron and iron transporting proteins such as neutrophil gelatinase-associated lipocalin (NGAL) have been proposed as potential antecedents of clinical symptoms in PE. This study investigates for the first time the possible role of iron, hypoxia, and NGAL in the etiology of PE using cultures of cytotrophoblasts (CTs) and decidual cells (DCs). STUDY DESIGN: To assess NGAL protein expression in PE, we analyzed placental tissues from normotensive (GA: 31 [30-32] wks) vs preeclamptic patients (GA: 31 [28-32] wks) by immunohistochemistry (IHC) and H-score analysis. CTs and DCs were isolated and purified from normal term placentas delivered by cesarean (n 8). To mimic the increased iron level and hypoxic environment in PE, cells were supplemented with iron citrate (25M) and exposed to normoxic (NMX; 20% O2) or hypoxic conditions (HPX; 2% O2 for 24h. NGAL protein and mRNA levels were measured by western blot and RTqPCR. RESULTS: (1) IHC revealed elevated NGAL protein expression in both extravillous trophoblast (EVT) and decidua in PE vs control (H-score: meanSEM): 375.175.7 vs 44.18.8 (p 0.003) and 286.352.7 vs 80.613.9 (p 0.001), respectively; (2) In CTs, iron supplementation increased NGAL expression under HPX (33.4-fold, p 0.0019), but not NMX; (3) In CTs, iron supplementation increased NGAL mRNA levels 3-fold under NMX but 175-fold under HPX (60-fold higher compared with HPX alone). Thus, HPX increased NGAL mRNA and protein expression in CTs in an iron-dependent manner. CONCLUSION: These data demonstrate that enhanced NGAL expression in EVT and decidua is a novel marker of PE. Further, our in vitro studies suggest that CT NGAL levels are elevated in PE through an iron-dependent, HPX-driven mechanism that is mediated at the level of gene transcription.

Up-regulation of neutrophil gelatinase-associated lipocalin in cholesteatoma

Conclusion. Neutrophil gelatinase-associated lipocalin (NGAL) and Ki-67 expression were up-regulated in cholesteatoma and the expression pattern of NGAL in the epithelial layer was inversely related to the expression of Ki-67. Therefore, NGAL may be related to dysregulated differentiation in the keratinocytes during the development of a cholesteatoma. Objectives. We investigated the differential expression and localization of NGAL in middle ear cholesteatoma and compared the results to normal external auditory canal (EAC) skin. We also compared the expression and localization of NGAL with the expression and localization of Ki-67 in middle ear cholesteatoma. Subjects and methods. Tissue samples from middle ear cholesteatomas and normal EAC skin were obtained from 20 patients undergoing middle ear surgery. NGAL mRNA expression was determined by the reverse transcriptase-polymerase chain reaction (RT-PCR). The expression of NGAL protein was analyzed by Western blot. NGAL and Ki-67 were localized by immunohistochemical staining. Results. A significantly greater expression of the NGAL mRNA was observed in cholesteatoma epithelium than in normal EAC skin (p < 0.05). NGAL was detected in the granular layer of cholesteatoma. However, NGAL was scarcely expressed in normal EAC skin. Ki-67 was detected predominantly in the basal and parabasal layers of cholesteatoma epithelium.

Expression of Neutrophil Gelatinase—Associated Lipocalin in Human Salivary Glands

We performed an observational study of RNA and protein expression in human tissue to examine the distribution of neutrophil gelatinase-associated lipocalin (NGAL) in normal and chronic inflammatory salivary tissues, and to investigate the expression level of NGAL in inflammatory conditions of salivary glands. Normal salivary gland tissues and tissue samples of salivary glands with chronic sialadenitis were obtained. Expression of NGAL was investigated by reverse transcriptase-polymerase chain reaction, and semiquantitative analysis of these results was also performed. The differential localization and amount of immunoreactivity to NGAL protein was evaluated by immunohistochemistry and Western blot analysis in normal salivary gland tissues and salivary glands with chronic sialadenitis. NGAL messenger RNA transcripts were detected in the tissues from the salivary glands with chronic sialadenitis, but only a small amount was detected in the tissues from the normal salivary glands. A weak expression of NGAL protein was occasionally seen in a few ductal epithelial cells of normal salivary gland tissue. However, in tissue samples from glands with chronic sialadenitis, the NGAL protein was expressed strongly in ductal epithelial cells and infiltrating inflammatory cells. These results imply that NGAL is associated with the regulation of inflammation in salivary glands.

Neutrophil gelatinase-associated lipocalin in normal and neoplastic human tissues. Cell type-specific pattern of expression.

Neutrophil gelatinase-associated lipocalin (NGAL) has recently been identified in myeloperoxidase-negative neutrophil granules. Members of the lipocalin family are thought to bind and transport small lipophilic molecules such as retinoids and roles in cell regulation have been proposed. Recently, NGAL has also been demonstrated in the colonic mucosa in certain pathologic conditions. The aim of this study was to examine the distribution of NGAL in normal and neoplastic tissues by immunohistochemistry. Interestingly, NGAL was found in a variety of normal and pathological human tissues. A cell type-specific pattern of expression was seen in bronchus, stomach, small intestine, pancreas, kidney, prostate gland, and thymus. The comparative analysis of the putative rat homologue neu-related lipocalin showed a very similar pattern of expression with the exception of pancreas and kidney. Neoplastic human tissues showed a very heterogeneous expression of NGAL protein. High NGAL levels were found in adenocarcinomas of lung, colon and pancreas. In contrast, renal cell carcinomas of various subtypes and prostate cancers contained low NGAL levels. Lymphomas and thymic tumours were negative for NGAL immuno-labeling. Knowledge about the location of NGAL in normal cells and in disease states provides the first clues towards understanding its biological function.