24p3 in differentiation of myeloid cells

The impact of hydrocortisone treatment on neutrophil gelatinase-associated lipocalin release in porcine endotoxemic shock

Background

A key feature of sepsis is systemic inflammatory activation that could be counteracted by steroids. In this experimental model of systemic inflammation, we sought to investigate whether septic neutrophil activation, evaluated by the plasma levels of neutrophil gelatinase-associated protein (NGAL), is modulated by the timing of hydrocortisone treatment.

Methods

Sixteen anesthetized pigs were allocated to one of four equally sized groups. Three of these groups received endotoxin at 2 μg × kg⁻¹ × h⁻¹ for 6 h so as to induce endotoxemic shock. Hydrocortisone (5 mg × kg⁻¹) was administered intravenously before endotoxemic challenge, or at the onset of endotoxemic shock. Endotoxemic pigs not receiving hydrocortisone and non-endotoxemic pigs served as control groups. Physiologic variables, hematology, and biochemistry, including plasma NGAL, were measured repeatedly.

Results

Hydrocortisone treatment prior to endotoxemia attenuated some inflammatory, hematological, circulatory, and metabolic manifestations of shock (i.e., higher white blood cell count, higher mean arterial pressure, lower heart rate and mean pulmonary arterial pressure, higher left ventricular stroke work index, higher base excess). Endotoxemic shock increased plasma NGAL (p < 0.001). In pigs given hydrocortisone before the endotoxin infusion, plasma NGAL was lower as compared to those given hydrocortisone at endotoxemic shock (p < 0.05). Plasma NGAL levels correlated inversely to neutrophil granulocyte counts (rho = −0.65) but not to urine output (rho = −0.10) at the end of the experiment.

Conclusions

The increase in plasma NGAL is counteracted by hydrocortisone administration prior to endotoxemia; concomitantly, this treatment was associated with less expressed circulatory derangement. Urine NGAL did not differ between the groups, suggesting that the NGAL response was not primarily related to kidney injury.

Neutrophil gelatinase-associated lipocalin and innate immune responses to bacterial infections

Neutrophil gelatinase-associated lipocalin (NGAL), an essential component of the antimicrobial innate immune system, is present in neutrophils and multiple other tissues. It prevents iron acquisition by microorganisms by sequestering iron-loaded bacterial siderophores. NGAL also modulates neutrophil functions. Its production is inducible following Toll-like receptor 4 activation and release of pro-inflammatory cytokines. NGAL is employed clinically in the diagnosis of acute kidney injury and may be useful in general in the differential diagnosis of a bacterial-mediated infectious process. Elevated levels of NGAL have been detected in the blood of patients with bacterial urinary tract infection, community-acquired pneumonia, sepsis, as well as in the cerebrospinal fluid and peritoneal fluid of patients with bacterial meningitis and peritonitis. Some bacteria have developed resistance to NGAL-mediated iron sequestration by production of modified siderophores that are not recognized by NGAL.

Plasma neutrophil gelatinase associated lipocalin (NGAL) is associated with kidney function in uraemic patients before and after kidney transplantation

Background

Neutrophil gelatinase associated lipocalin (NGAL) is a biomarker of kidney injury. We examined plasma levels of NGAL in a cohort of 57 kidney allograft recipients (Tx group, 39 ± 13 years), a uraemic group of 40 patients remaining on the waiting list (47 ± 11 years) and a control group of 14 healthy subjects matched for age, sex and body mass index (BMI). The kidney graft recipients were studied at baseline before transplantation and 3 and 12 months after transplantation and the uraemic group at baseline and after 12 months.

Methods

NGAL was measured using a validated in-house Time-Resolved Immuno-flourometric assay (TRIFMA). Repeated measurements differed by < 10% and mean values were used for statistical analyses. Spearman rank order correlation analysis and the Kruskal-Wallis non-parametric test were used to evaluate the association of NGAL concentrations with clinical parameters.

Results

Plasma NGAL levels before transplantation in the Tx and uraemic groups were significantly higher than in the healthy controls (1,251 μg/L, 1,478 μg/L vs. 163 μg/L, p < 0.0001). In the Tx group NGAL concentrations were associated with serum creatinine (R = 0.51, p < 0.0001), duration of end-stage renal failure (R = 0.41, p = 0.002) and leukocyte count (R = 0.29, p < 0.026). At 3 and 12 months plasma NGAL concentrations declined to 223 μg/L and 243 μg/L, respectively and were associated with homocysteine (R = 0.39, p = 0.0051 and R = 0.47, p = 0.0007).

Conclusions

Plasma NGAL is a novel marker of kidney function, which correlates to duration of end-stage renal failure (ESRD) and serum creatinine in uraemic patients awaiting kidney transplantation. Plasma NGAL is associated with homocysteine in transplanted patients. The prognostic value of these findings requires further studies.

Laser capture microdissection and genetic analysis of carbon-labeled Kupffer cells

AIM: To develop a method of labeling and micro-dissecting mouse Kupffer cells within an extraordinarily short period of time using laser capture microdissection (LCM).

METHODS: Tissues are complex structures comprised of a heterogeneous population of interconnected cells. LCM offers a method of isolating a single cell type from specific regions of a tissue section. LCM is an essential approach used in conjunction with molecular analysis to study the functional interaction of cells in their native tissue environment. The process of labeling and acquiring cells by LCM prior to mRNA isolation can be elaborate, thereby subjecting the RNA to considerable degradation. Kupffer cell labeling is achieved by injecting India ink intravenously, thus circumventing the need for in vitro staining. The significance of this novel approach was validated using a cholestatic liver injury model.

RESULTS: mRNA extracted from the microdissected cell population displayed marked increases in colony-stimulating factor-1 receptor and Kupffer cell receptor message expression, which demonstrated Kupffer cell enrichment. Gene expression by Kupffer cells derived from bile-duct-ligated, versus sham-operated, mice was compared. Microarray analysis revealed a significant (2.5-fold, q value < 10) change in 493 genes. Based on this fold-change and a standardized PubMed search, 10 genes were identified that were relevant to the ability of Kupffer cells to suppress liver injury.

CONCLUSION: The methodology outlined herein provides an approach to isolating high quality RNA from Kupffer cells, without altering the tissue integrity.

Neutrophil gelatinase-associated lipocalin expression in chronic myeloid leukemia

The murine equivalent of neutrophil gelatinase-associated lipocalin (NGAL) was previously found to be increased by BCR-ABL expression in murine models of chronic myeloid leukemia (CML). Our study evaluates, in CML patients at various clinical stages, the levels of NGAL mRNA in blood samples and protein in sera. A highly significant increase of mRNA expression and protein secretion was shown in patients at diagnosis. The parallel expression of NGAL and BCR-ABL at the early stage of CML process allows us to suggest that NGAL could play an important role in the physiopathology of CML.

Acute endotoxemia is associated with upregulation of lipocalin 24p3/Lcn2 in lung and liver

Acute endotoxemia is associated with production of acute phase proteins which regulate inflammatory responses to tissue injury. Consistent with DNA microarray experiments, we found that acute endotoxemia, induced by administration of lipopolysaccharide (LPS) to mice (1 mg/kg) or rats (5 mg/kg), resulted in increased expression of the hepatic acute phase protein, lipocalin 24p3, which was evident within 4 h and persisted for 24-48 h. Increases in 24p3 expression were also observed in the lung after LPS administration, as well as in isolated liver and lung macrophages, and Type II alveolar epithelial cells. The actions of LPS are dependent, in part, on Toll-like receptor (TLR) proteins. Macrophages from C3H/HeJ mice, which possess a nonfunctional TLR-4, expressed low levels of 24p3 mRNA when compared to cells from control C3H/OuJ mice. Whereas LPS administration increased 24p3 expression in lung and liver macrophages from control C3H/OuJ mice, minimal effects were observed in TLR-4 mutant mice demonstrating that TLR-4 is important in regulating 24p3 expression during acute endotoxemia. Promoters for genes encoding lipocalin proteins including 24p3 contain consensus sequences for transcription factors including NF-kappaB, and C/EBP. Acute endotoxemia resulted in NF-kappaB nuclear binding activity in both alveolar macrophages and Type II cells. In contrast, C/EBP activation was evident only in Type II cells, suggesting differential effects of LPS on these cell types. These data suggest that the acute phase response to acute endotoxemia involves induction of 24p3 in both the lung and liver. This protein may be important in restoring tissue homeostasis following LPS-induced injury.

Expression profiles of micro RNA in proliferating and differentiating 32D murine myeloid cells

32D cells are murine myeloid cells that grow indefinitely in Interleukin-3 (IL-3). In these cells, the type 1 insulin-like growth factor (IGF-I) and granulocytic-colony stimulating factor (G-CSF) induce differentiation to granulocytes. 32D cells do not express insulin receptor substrate-1 (IRS-1) or IRS-2, docking proteins of the IGF-I receptor. Ectopic expression of IRS-1 in these cells inhibits differentiation, the cells become IL-3 independent and IGF-1 dependent and can form tumors in mice. 32D and 32D-derived cells offer a good model in which to study the expression profiles of Micro Rna (miR) related to sustained proliferation or differentiation. We present here the data obtained with miR micro-arrays and identify the miR that are regulated by IGF-1 or G-CSF and are associated with either differentiation or indefinite cell proliferation of 32D murine myeloid cells.