Membrane glucocorticoid receptors are down regulated by glucocorticoids in patients with systemic lupus erythematosus and use a caveolin-1-independent expression pathway.

BACKGROUND: Membrane-bound glucocorticoid receptors (mGCR) are up regulated on monocytes after in vitro stimulation and in patients with rheumatoid arthritis. Caveolin-1 is critical for the transport of plasma membrane oestrogen receptors to the cell surface. OBJECTIVES: To investigate the expression of mGCR in patients with systemic lupus erythematosus (SLE)-a disease with different aetiopathogenesis and treatment regimens-and to examine whether caveolin-1 is critical for the transport of mGCR to the cell surface. METHODS: Frequencies of mGCR+ peripheral blood mononuclear cells were measured using high-sensitivity immunofluorescent staining and tested for correlation with SLE disease activity and glucocorticoid treatment. Semiquantitative polymerase chain reaction, immunofluorescence, recombinant expression and confocal laser-scanning microscopy were used to search for an association of mGCR with caveolin-1. RESULTS: The frequencies of mGCR+ monocytes (CD14+) were considerably higher in patients with SLE (n = 33) than in healthy controls (n = 58), whereas B cells (CD19+) were not different in this regard. T cells (CD3+) were always mGCR-. The frequency of mGCR+ monocytes in patients with SLE did not correlate with disease activity, but did inversely correlate with glucocorticoid dosages; this inverse correlation was confirmed by corresponding in vitro experiments with stimulated monocytes. The induced up regulation of mGCR was not accompanied by an up regulation of caveolin-1, and mGCR are not colocalised with caveolin-1 in plasma membrane caveolae. CONCLUSION: mGCR are (a) up regulated in patients with SLE and by inflammatory stimuli and (b) down regulated by glucocorticoids, suggesting a negative feedback loop to control glucocorticoid action. Drugs binding selectively to mGCR may in future prove to be of therapeutic value.

Elevated serum concentration of cardiotoxic lipid peroxidation products in chronic renal failure in relation to severity of renal anemia.

Patients with end-stage renal disease undergoing hemodialysis (HD) are exposed to oxidative stress. Increased levels of malondialdehyde (MDA) and 4-hydroxylnonenal (HNE) were found in plasma of uremic patients indicating accelerated lipid peroxidation (LPO) as a consequence of multiple pathogenetic factors. The catabolism and action of those products was already intensively studied. As highly reactive metabolites they are able to bind to proteins, nucleic acids, and other molecules. Doing so, they exert molecular signal effects in cells and are able to exacerbate tissue and organ damage, e.g. cardiotoxic effects. Since renal anemia was shown to promote oxidative stress as well, the aim of our investigation was to examine its role in HD patients. Therefore, two groups of HD patients were investigated (group I Hb < 10 g/dl, group II Hb > 10 g/dl) and serum concentrations of MDA, HNE, and of protein carbonyls, a marker for protein oxidation, were determined. All HD patients had significantly higher levels of the LPO products MDA and HNE compared with controls. However, group I patients showed higher MDA and HNE concentrations compared to group II patients. The same result could be seen for protein carbonyls. During HD concentration of both LPO products decreased. However, this was not the case for protein carbonyls. These results lead to the conclusion that optimized correction of the renal anemia may result in a significant reduction of oxidative stress and therefore in the reduction of organ tissue damage. In this way correction of renal anemia will reduce the cardiovascular risk and comorbidity of HD patients improving their prognosis.

4-Hydroxynonenal, a novel indicator of lipid peroxidation for reperfusion injury of the myocardium.

4-Hydroxynonenal (HNE) has been proposed as an important marker of radical-induced lipid peroxidation (LPO) during postischemic reperfusion injury of the myocardium. Therefore, the liberation of HNE into the effluent of isolated perfused rat hearts was investigated. For the first time, the formation of the aldehyde is demonstrated in myocardium. During control perfusion, 1.28 +/- 0.33 pmol HNE.min-1.mg protein-1 were formed by the hearts of 18-mo-old Wistar-Kyoto (WKY) rats and 2.74 +/- 1.12 pmol.min-1.mg protein-1 by those of 18-mo-old spontaneously hypertensive (SHR) rats, respectively. In the WKY group, HNE release increased to 3.35 +/- 1.13 pmol.min-1.mg protein-1 2 min after the onset of reperfusion following 30 min of total and global ischemia compared with the preischemic control period (P < 0.05). In the SHR group, HNE liberation was higher during reperfusion (8.66 +/- 1.33 pmol.min-1.mg protein-1, maximum at 2 min reperfusion) compared with both the respective preischemic control and the respective reperfusion interval of the WKY group (P < 0.05 each). The SHR rats showed signs of congestive cardiac failure of a decompensated hypertrophy in comparison to the normotensive WKY rats. Moreover, the SHR rat hearts exhibited a lower release of adenine nucleotide degradation products (adenine, inosine, hypoxanthine plus uric acid: 48.1 +/- 10.2 nmol.30 min-1.mg protein-1; P < 0.05) and a diminished functional recovery (left ventricular developed pressure, 32 +/- 16 mmHg; P < 0.05) during 30 min of reperfusion compared with the WKY group (77.9 +/- 14.4 nmol.30 min-1.mg protein-1; 90 +/- 21 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)

Balancing of energy-consuming processes of K 562 cells.

A balance of ATP-consuming processes in human erythroleukemia (K 562) cells by use of the decreased 14CO2 formation from [1-14C]-glutamate following inhibition of energy-requiring processes is presented. This method was tested on Ehrlich mouse ascites tumour cells and was used in suspensions of K 562 cells with a low cell content. More than 90 percent of the ATP produced by oxidative phosphorylation could be accounted for in K 562 cells. Protein synthesis consumed about 35 percent, Na+/K(+)-ATPase about 20 percent and transcription processes 5-10 percent of the total ATP. The share of the Ca(2+)-dependent reactions was notably high at 25 percent in comparison with Ehrlich mouse ascites tumour cells, reticulocytes or hepatocytes. ATP consumption by DNA synthesis was assessed at 5-10 percent. Only less than 10 percent of the consumption of ATP produced oxidatively remained for other cellular reactions. The degree of coupling of K 562 cells was high in comparison with that of other eukaryotic cell types.

Adenine metabolism of Ehrlich mouse ascites cells in proliferating and resting phase of tumor growth.

The incorporation of 14C from [U-14C]adenine into the pools of purine nucleotides, nucleosides and bases in Ehrlich mouse ascites cells (EMAC1) during the proliferating and resting phases of tumor growth was compared. In the proliferating phase the total 14C incorporation into purine pools is much faster than in the resting phase. The ATP turnover as well as the purine breakdown to hypoxanthine and uric acid are increased in the proliferating phase. That corresponds to previous findings on higher nucleotide pool sizes and higher ATP yield and ATP-consuming processes in this growth period.

Balancing of mitochondrial and glycolytic ATP production and of the ATP-consuming processes of Ehrlich mouse ascites tumour cells in a high phosphate medium.

A balance of energy budgeting of Ehrlich mouse ascites tumour cells including mitochondrial and glycolytic ATP production and about 80% of ATP consumption in a high phosphate medium is presented. In the share of glycolysis was about one-third of the total ATP production, more than twice that found in a low phosphate medium. The extent of a single energy reaction was assessed from the decrease of coupled oxygen consumption and lactate formation following the specific inhibition of this process. The inhibitory effects on coupled respiration and glycolysis were identical for the energy consuming processes measured: protein turnover, Na+/K(+)-ATPase, Ca2(+)-transport and RNA synthesis.