In vitro glucocorticoid sensitivity is associated with clinical glucocorticoid therapy outcome in rheumatoid arthritis

Introduction

Genetic and disease-related factors give rise to a wide spectrum of glucocorticoid (GC) sensitivity in rheumatoid arthritis (RA). In clinical practice, GC treatment is not adapted to these differences in GC sensitivity. In vitro assessment of GC sensitivity before the start of therapy could allow more individualized GC therapy. The aim of the study was to investigate the association between in vitro and in vivo GC sensitivity in RA.

Methods

Thirty-eight early and 37 established RA patients were prospectively studied. In vitro GC sensitivity was assessed with dexamethasone-induced effects on interleukin-2 (IL-2) and glucocorticoid-induced leucine zipper (GILZ) messenger RNA expression in peripheral blood mononuclear cells (PBMCs). A whole-cell dexamethasone-binding assay was used to measure number and affinity (1/K_D) of glucocorticoid receptors (GRs).In vivo GC sensitivity was determined by measuring the disease activity score (DAS) and health assessment questionnaire disability index (HAQ-DI) score before and after 2 weeks of standardized GC treatment.

Results

GR number was positively correlated with improvement in DAS. IL-2-EC₅₀ and GILZ-EC₅₀ values both had weak near-significant correlations with clinical improvement in DAS in intramuscularly treated patients only. HAQ responders had lower GILZ-EC₅₀ values and higher GR number and K_D.

Conclusions

Baseline cellular in vitro glucocorticoid sensitivity is modestly associated with in vivo improvement in DAS and HAQ-DI score after GC bridging therapy in RA. Further studies are needed to evaluate whether in vitro GC sensitivity may support the development of tailor-made GC therapy in RA.     

The lipid requirement of the (Ca2+ + Mg2+)-ATPase in the human erythrocyte membrane, as studied by various highly purified phospholipases.

1. When complete hydrolysis of glycerophosphlipids and sphingomyelin in the outer membrane leaflet is brought about by treatment of intact red blood cells with phospholipase A2 and sphingomyelinase C, the (Ca2+ + Mg2+)-ATPase activity is not affected. 2. Complete hydrolysis of sphingomyelin, by treatment of leaky ghosts with spingomyelinase C, does not lead to an inactivation of the (Ca2+ + Mg2+)-ATPase. 3. Treatment of ghosts with phospholipase A2 (from either procine pancreas of Naja naja venom), under conditions causing an essentially complete hydrolysis of the total glycerophospholipid fraction of the membrane, results in inactivation of the (Ca2+ + Mg2+)-ATPase by some 80--85%. The residual activity is lost when the produced lyso-compounds (and fatty acids) are removed by subsequent treatment of the ghosts with bovine serum albumin. 4. The degree of inactivation of the (Ca2+ + Mg2+)-ATPase, caused by treatment of ghosts with phospholipase C, is directly proportional to the percentage by which the glycerophospholipid fraction in the inner membrane layer is degraded. 5. After essentially complete inactivation of the (Ca2+ + Mg2+)-ATPase by treatment of ghosts with phospholipase C from Bacillus cereus, the enzyme is reactivated by the addition of any of the glycerophospholipids, phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine or lysophosphatidylcholine, but not by addition of sphingomyeline, free fatty acids or the detergent Triton X-100. 6. It is concluded that only the glycerophospholipids in the human erythrocyte membrane are involved in the maintenance of the (Ca2+ + Mg2+)-ATPase activity, and in particular that fraction of these phospholipids located in the inner half of the membrane.     

Localization of acetylcholine receptors and synaptic ultrastructure at nerve-muscle contacts in culture: dependence on nerve type

In cultures of xenopus myotomal muscle cells and spinal cord (SC) some of the nerve-muscle contacts exhibit a high density of acetylcholine receptors (AchRs [Anderson et al., 1977, J. Physiol. (Lond.). 268:731- 756,757-773]) and synaptic ultrastructure (Weldon and Cohen, 1979, J. Neurocytol. 8:239-259). We have examined whether similarly specialized contacts are established when the muscle cells are cultured with explants of xenopus dorsal root ganglia (DRG) or sympathetic ganglia (SG). The outgrowth from the ganglionic explants contained neuronal and non- neuronal cell processes. Although both types of processes approached within 100 A of muscle cells, synaptic ultrastructure was rarely observed at these contacts. Because patches of postsynaptic ultrastructure also develop on noncontacted muscle cells, the very few examples of contacts with such specializations probably occurred by chance. AChRs were stained with fluroscent α-bungarotoxin. More than 70 percent of the SC-contacted muscle cells exhibited a high receptor density along the path of contact. The corresponding values for DRG- and SG- contacted muscle cells were 10 and 6 percent. Similar values were obtained when the ganlionic and SC explants were cultured together in the same chamber. The few examples of high receptor density at ganglionic-muscle contacts resembled the characteristic receptor patches of noncontacted muscle cells rather than the narrow bands of high receptor density seen at SC-muscle contacts. In addition, more than 90 percent of these ganglionic- contacted muscle cells had receptor patches elsewhere, compared to less than 40 percent for the SC-contacted muscle cells. These findings indicate that the SC neurites possess a specific property which is important for the establishment of synaptically specialized contacts with muscle and that this property is lacking in the DRG and SG neurites.     

Analysis of the genomic response of human prostate cancer cells to histone deacetylase inhibitors

Histone deacetylases (HDACs) have emerged as important targets for cancer treatment. HDAC-inhibitors (HDACis) are well tolerated in patients and have been approved for the treatment of patients with cutaneous T-cell lymphoma (CTCL). To improve the clinical benefit of HDACis in solid tumors, combination strategies with HDACis could be employed. In this study, we applied Analysis of Functional Annotation (AFA) to provide a comprehensive list of genes and pathways affected upon HDACi-treatment in prostate cancer cells. This approach provides an unbiased and objective approach to high throughput data mining. By performing AFA on gene expression data from prostate cancer cell lines DU-145 (an HDACi-sensitive cell line) and PC3 (a relatively HDACi-resistant cell line) treated with HDACis valproic acid or vorinostat, we identified biological processes that are affected by HDACis and are therefore potential treatment targets for combination therapy. Our analysis revealed that HDAC-inhibition resulted among others in upregulation of major histocompatibility complex (MHC) genes and deregulation of the mitotic spindle checkpoint by downregulation of genes involved in mitosis. These findings were confirmed by AFA on publicly available data sets from HDACi-treated prostate cancer cells. In total, we analyzed 375 microarrays with HDACi treated and non-treated (control) prostate cancer cells. All results from this extensive analysis are provided as an online research source (available at the journal’s website and at http://luigimarchionni.org/HDACIs.html). By publishing this data, we aim to enhance our understanding of the cellular changes after HDAC-inhibition, and to identify novel potential combination strategies with HDACis for the treatment of prostate cancer patients.     

Differential analysis of protein expression of Bifidobacterium grown on different carbohydrates

We observed recently that colonic fermentation of lactose might be a major factor in the pathophysiology of lactose intolerance. Proteomic techniques could be helpful in interpreting the metabolic pathways of lactose fermentation. The objective of this study was to explore proteomic methodologies for studying bacterial lactose metabolism that can be used to detect and identify proteins associated with the onset of intolerance symptoms. Differential expression of cytoplasmic proteins of Bifidobacterium animalis, Bifidobacterium breve and Bifidobacterium longum grown on different carbohydrates (lactose, glucose, galactose) was analyzed with surface-enhanced laser desorption ionization-time of flight (SELDI-TOF) MS and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). After fractionation by SDS-PAGE, differentially-expressed proteins were identified with LC-MS/MS. The three strains grown on the same carbohydrate or the same strain grown on glucose or lactose showed differences in SELDI-TOF MS protein profiles. Differences in protein expression were observed in B. breve grown on glucose, galactose or lactose as analyzed with SDS-PAGE. With LC-MS/MS, proteins from Bifidobacterium were identified, which included enzymes for metabolism of lactose, glucose and galactose. In conclusion, the applied techniques can discern differences in protein expression of bacteria metabolizing different carbohydrates. These techniques are promising in studying metabolism of lactose and other substrates in a complex bacterial ecosystem such as the colonic microbiota.     

Temperature-dependent vesiculation of human erythrocytes caused by hypertonic salt: A phenomenon involving lipid segregation

Treatment of human erythrocytes with 4 M NaCl causes hemolysis with concomitant release of microvesicles from the membrane. The microvesicles have an average diameter of 200–300 nm and reveal an in creased lipid content in particular of cholesterol and sphingomyelin. Phosphatidylcholine and phosphatidylserine contents remain unaltered whereas the phosphatidylethanolamine content is lowered in comparison with the erythrocyte membrane.Decreasing the temperature at which the microvesicles are produced causes an increase in the cholesterol/phospholipid ratio, the sphingomyelin/phosphatidylethanolamine ratio, and the amino-phospholipids, which contain low amounts of arachidonic acid.The total protein content of the vesicles is further decreased when the temperature is lowered. This is due to a reduced content of spectrin and several integral membrane proteins. The results indicate that a significant, temperature-dependent segregation of membrane constituents occurs during the vesiculation process.     

Hyperlipidemia and atherosclerosis associated with liver disease in ferrochelatase-deficient mice

Erythropoietic protoporphyria (EPP) is an inherited disorder of heme synthesis caused by deficiency of the mitochondrial enzyme ferrochelatase. EPP in humans is associated with liver disease, hypertriglyceridemia, and a low level of high density lipoprotein (HDL) cholesterol. To explore consequences of ferrochelatase deficiency in lipid metabolism, we have analyzed hepatic lipid content and plasma lipoprotein levels in chow-fed BALB/c mice homozygous ( fch/fch) or heterozygous ( fch/1) for a point mutation in the ferrochelatase gene and in wild-type controls (1/1). Livers of fch/fch mice show bile duct proliferation and biliary fibrosis, but bile formation is not impaired. The free cholesterol content of fch/fch livers is significantly increased when compared with fch/1 and 1/1 livers. Plasma cholesterol in fch/fch mice (9.9 +/- 6.4 mM) is elevated when compared with fch/1 and 1/1 mice (2.9 +/- 0.2 and 2.5 +/- 0.3 mM, respectively), because of an increased cholesterol content in the very low density lipoprotein-sized fractions, whereas HDL cholesterol is reduced. The ratio of cholesteryl ester to free cholesterol is 4.3 +/- 0.6, 3.3 +/- 0.3, and 0.3 +/- 0.1 in the plasma of 1/1, fch/1, and fch/fch mice, respectively. The latter is not due to reduced lecithin:cholesterol acyltransferase activity in plasma of fch/fch mice but to the presence of lipoprotein-X (Lp-X), a particle composed of bile-type lipids usually seen only in cholestatic conditions. Expression of mdr2, essential for biliary phospholipid/cholesterol secretion, is increased in fch/fch livers. In spite of this, biliary phospholipid/cholesterol secretion is reduced relative to that of bile salts. It is postulated that an inability of bile salts to stimulate lipid secretion adequately leads to formation of Lp-X in this noncholestatic condition. Distinct atherosclerotic lesions were found in aged fch/fch mice.Thus, ferrochelatase deficiency in mice leads to liver disease associated with altered hepatic lipid metabolism, a characteristic hyperlipidemia, and development of atherosclerosis.-Bloks, V. W., T. Pl?sch, H. van Goor, H. Roelofsen, J. Baller, R. Havinga, H. J. Verkade, A. van Tol, P. L. M. Jansen, and F. Kuipers. Hyperlipidemia and atherosclerosis associated with liver disease in ferrochelatase-deficient mice. J. Lipid Res. 2001. 42: 41;-50.     

Analyses of intricate kinetics of the serum proteome during and after colon surgery by protein expression time series

Monitoring changes in serum protein expression in response to acute events such as trauma, infection or drug intervention may reveal key proteins of great value in predicting recovery or treatment response. Concerted actions of many proteins are expected. Proteins sharing similar expression changes may function in the same physiological process. As a model we analyzed expression changes in serum of colon cancer patients, before, during, and after laparoscopic colon resection. Eight samples were taken from each of four patients before, during, and up to 5 days after surgery. Total serum and a low molecular weight fraction were analyzed by SELDI-TOF-MS. In total 146 masses were detected. A principal components analysis (PCA) illustrates the temporal variation in the postsurgery proteome. Time series for each mass could be clustered into four distinct groups based on similarity in expression pattern. Two masses of 11.4 and 11.6 kDa, part of a slow response cluster, were identified as forms of the acute phase protein serum amyloid A (SAA). Fourteen more proteins belong to this cluster and may also function in acute phase response. We present an approach to analyze temporal variation in the proteome. This approach may be useful to evaluate surgical, nutritional, and pharmacological interventions.     

Polymorphism and divergence at the 5' flanking region of the sex- determining locus, Sry, in mice

We have investigated patterns of evolution in the nonrecombining portion of the Y chromosome in mice by comparing levels of polymorphism within Mus domesticus with levels of divergence between M. domesticus and M. spretus. A 1,277-bp fragment of noncoding sequence flanking the sex determining locus (Sry) was PCR amplified, and 1,063 bases were sequenced and compared among 20 M. domesticus and 1 M. spretus. Two polymorphic base substitutions and two polymorphic insertion/deletion sites were identified within M. domesticus; nucleotide diversity was estimated to be 0.1%. Divergence between M. domesticus and M. spretus for this region (1.9%) was slightly lower than the average divergence of single-copy nuclear DNA for these species. Comparison of levels of polymorphism and divergence at Sry with levels of polymorphism and divergence in the mitochondrial DNA control region provided no evidence of a departure from the expectations of neutral molecular evolution. These findings are consistent with the presumed lack of function for much of the Y chromosome.