MicroRNA regulate immunological pathways in T-cells in immune thrombocytopenia (ITP).

MicroRNA are small noncoding RNA molecules that regulate gene expression. To investigate the role of microRNA in immune thrombocytopenia (ITP), we performed genome-wide expression analyses of mRNA and microRNA in T cells from ITP patients and controls. We identified 1915 regulated genes and 22 regulated microRNA that differed between ITP patients and controls. Seventeen of the 22 regulated microRNA were linked to changes in target gene expression; 57 of these target genes were associated with the immune system, eg, T-cell activation and regulation of immunoglobulin production. CXCL13 and IL-21 were two microRNA target genes significantly increased in ITP. We could demonstrate increased plasma levels of CXCL13 and others have reported increased plasma levels of interleukin-21 in ITP. Thus, regulated microRNA were significantly associated with both gene and protein expression of molecules in immunological pathways. We suggest that microRNA may be important regulatory molecules involved in the loss of tolerance in ITP.

Differences in gene expression and cytokine levels between newly diagnosed and chronic pediatric ITP.

Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely. In the majority of children the disease resolves, but in some it becomes chronic. To investigate whether these 2 phases of the disease are molecularly similar or separate entities we performed DNA microarray analysis (GEO accession number: GSE46922) of T-cells from newly diagnosed children and children with chronic ITP. We found complete separation of the gene expression profiles between the 2 phases of the disease. Furthermore, the gene expression levels of several cytokines differed between the 2 phases of the disease. This was also reflected in plasma with increased levels of interleukin (IL)-16 and TNF-related weak inducer of apoptosis and lower levels of IL-4 in newly diagnosed compared with chronic ITP. Thus, our data indicate that chronic ITP in childhood is a separate disease entity, dissimilar in many aspects to the newly diagnosed phase.

Altered cytokine levels in pediatric ITP.

Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely. In the majority of children, the disease resolves, but in some, it becomes chronic. Cytokines are important mediators of the immune response and are known to be dysregulated in autoimmune diseases. Therefore, our aim was to investigate differences in plasma levels of cytokines between children with ITP and healthy controls. We had two cohorts of children: one Swedish with 18 children with ITP and seven healthy children and a second Chinese one with 58 children with ITP and 30 healthy children. Plasma levels of chemokine (C-X3-C motif) ligand 1 (CX3CL1), transforming growth factor ß1 (TGF-ß1), and interleukin 22 (IL-22) were analyzed in both cohorts using enzyme-linked immunosorbent assays (ELISAs). We found lower plasma levels of TGF-ß1 and elevated levels of CX3CL1 and IL-22 in children with ITP compared with controls in both the Swedish and the Chinese cohort. In conclusion, all three cytokines differ between pediatric ITP and healthy controls and may, therefore, be potential biomarkers for the disease.

MicroRNA regulate immune pathways in T-cells in multiple sclerosis (MS).

BACKGROUND: MicroRNA are small noncoding RNA molecules that are involved in the control of gene expression. To investigate the role of microRNA in multiple sclerosis (MS), we performed genome-wide expression analyses of mRNA and microRNA in T-cells from MS patients and controls. METHODS: Heparin-anticoagulated peripheral blood was collected from MS-patients and healthy controls followed by isolation of T-cells. MicroRNA and RNA from T-cells was prepared and hybridized to Affymetrix miR 2.0 array and Affymetrix U133Plus 2.0 Human Genome array (Santa Clara, CA), respectively. Verifications were performed with real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). RESULTS: We identified 2,452 differentially expressed genes and 21 differentially expressed microRNA between MS patients and controls. By Kolmogorov-Smirnov test, 20 of 21 differentially expressed microRNA were shown to affect the expression of their target genes, many of which were involved in the immune system. Tumor necrosis factor ligand superfamily member 14 (TNFSF14) was a microRNA target gene significantly decreased in MS. The differential expression of mir-494, mir-197 and the predicted microRNA target gene TNFSF14 was verified by real-time PCR and ELISA. CONCLUSION: These findings indicate that microRNA may be important regulatory molecules in T-cells in MS.

MS risk genes are transcriptionally regulated in CSF leukocytes at relapse.

BACKGROUND: Infiltrating T-helper cells, cytotoxic T-cells, B-cells and monocytes are thought to mediate the damage to myelin, oligodendrocytes and axons in multiple sclerosis (MS), which results in progressive disability. OBJECTIVE: The objective of this paper is to explore gene expression profiles of leukocytes in the cerebrospinal fluid (CSF) compartment of MS patients during relapse. METHODS: Global gene expression was analyzed by DNA microarray analysis of cells in CSF from MS patients and controls, and verifications were performed with real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). RESULTS: Fifty percent of the recently described risk genes for MS and 28% of non-risk genes were differently expressed in MS patients compared to controls (χ(2)-test, p=7.7 × 10(-5)). Genes involved in T- and NK-cell processes were up-regulated, and genes involved in processes targeting innate immunity or B-cells were down-regulated in MS. Increased expression of EDN1 and CXCL11 and decreased expression of HMOX1 was verified with real-time PCR and increased expression of CXCL13 was verified with ELISA in CSF. CONCLUSION: DNA microarray analysis is useful in identifying differently expressed genes in CSF leukocytes, which may be important in MS in vivo. Our findings suggest that many of the risk genes for MS are differently expressed in the disease-mediating leukocytes that penetrate the blood-brain barrier.

Serum levels of LIGHT in MS.

BACKGROUND: Recently, a polymorphism in the LIGHT gene was shown to increase the risk of multiple sclerosis (MS) in a genome-wide association study (GWAS). OBJECTIVE: Our aim was to investigate if serum levels of LIGHT were affected by this polymorphism and by the disease itself. METHODS: Serum levels of LIGHT were investigated in four cohorts; 1) MS (n = 159) and controls (n = 160) in relation to rs1077667 genotype; 2) MS at relapse (n = 30) vs. healthy controls (n = 26); 3) MS (n = 27) vs. other neurological disease (OND, n = 33); and 4) MS patients before and after one year of treatment with natalizumab (n = 30). RESULTS: Carriers of the GG genotype had the lowest serum levels of LIGHT (p=0.02). Serum levels of LIGHT were increased in MS at relapse in two separate cohorts: vs. healthy controls (p=0.00005) and vs. remission (p=0.00006), other neurological disease (OND) (p=0.002) and OND with signs of inflammation (iOND; p=0.00005). Furthermore, serum levels of LIGHT were decreased by natalizumab treatment (p=0.001). CONCLUSION: Soluble LIGHT is an inhibitor of T-cell activation and GG carriers of rs1077667, with the highest risk for MS, had the lowest serum levels. The increased levels of LIGHT at times of increased MS activity suggest that soluble LIGHT is protective and may act to limit inflammation.

Increased number of B-cells in the red pulp of the spleen in ITP.

Platelets are targeted by autoantibodies and destroyed in the reticuloendothelial system in the spleen, liver and bone marrow in patients with immune thrombocytopenia (ITP). Other mechanisms such as destruction by cytotoxic T-cells and defective production of platelets in the bone marrow also exist. Splenectomy normalizes the platelet count in 70% of ITP patients, however, precious little is known about the spleen in this disease. Our aim was therefore to investigate the splenic morphology and especially the number and localization of splenic leukocytes in patients with ITP and controls and to evaluate factors predicting outcome of splenectomy. Spleen sections from 29 ITP patients and 11 individuals splenectomized due to trauma were analyzed by immunohistochemistry. All except one of the ITP patients had a normalized platelet count 12 months after splenectomy and the platelet count was inversely correlated with age. ITP patients had an increased number of B-cells in the red pulp. The number of white pulp B-cells and number of T-cells in both compartments was unchanged. In conclusion, B-cells are increased in the red pulp of the spleen and together with cytotoxic T-cells, helper T-cells and macrophages line the sinusoids enabling the immunological attack on platelets in ITP.

Familial dyslexia in a large Swedish family: a whole genome linkage scan.

There is a compelling body of evidence that developmental dyslexia runs in families and seems to be highly inheritable. Several investigations during the last two decades have shown possible locations of genes that might be involved in dyslexia, including regions of chromosomes 1, 2, 3, 6, 11, 13, 15 and 18. In addition, six candidate genes (KIAA0319, DYX1C1, DCDC2, ROBO1, MRPL19 and C2ORF3) seem to be related to dyslexia. The present study carried out a whole genome scan in a six-generation pedigree. In addition to literacy skills the assessment included cognitive skills and records concerning the history of reading and writing ability. Thirty-five percent were regarded as dyslexic in the family. A linkage analysis using both a quantitative and a qualitative approach has been performed. No evidence was obtained to support the hypothesis that the transmission of dyslexia in this pedigree is due to a highly penetrant major gene, and previous linkage findings were not replicated; however, power in this small study was not adequate to confirm linkage of genes with small to moderate effects. The results were discussed in relation to diagnostic procedures and sample characteristics.

T-cell-mediated cytotoxicity toward platelets in chronic idiopathic thrombocytopenic purpura.

Chronic idiopathic thrombocytopenic purpura (ITP) is a bleeding disorder that is characterized by increased platelet destruction and is believed to be autoantibody mediated. In this study, CD3+ T cells from ITP patients had increased expression of genes involved in cell-mediated cytotoxicity. In addition, cytotoxic cell-mediated lysis of autologous platelets was shown in active ITP. Our data suggest that T-cell-mediated cytotoxicity is an alternative mechanism for platelet destruction in ITP.

Regulation of carboxylesterase 1 (CES1) in human adipose tissue.

Carboxylesterase 1 (CES1) has recently been suggested to play a role in lipolysis. Our aim was to study the regulation of CES1 expression in human adipose tissue. In the SOS Sib Pair Study, CES1 expression was higher in obese compared with lean sisters (n=78 pairs, P=8.7x10(-18)) and brothers (n=12 pairs, P=0.048). CES1 expression was higher in subcutaneous compared with omental adipose tissue in lean (P=0.027) and obese subjects (P=0.00036), and reduced during diet-induced weight loss (n=24, weeks 8, 16, and 18 compared to baseline, P<0.0001 for all time points). CES1 expression was higher in isolated adipocytes compared with intact adipose tissue (P=0.0018) and higher in large compared with small adipocytes (P=4.1x10(-6)). Basal and stimulated lipolysis was not different in individuals with high, intermediate, and low expression of CES1. Thus, CES1 expression was linked to body fat and adipocyte fat content but not to lipolytic activity.

Expression profiling of macrophages from subjects with atherosclerosis to identify novel susceptibility genes.

Although a number of environmental risk factors for atherosclerosis have been identified, heredity seems to be a significant independent risk factor. The aim of our study was to identify novel susceptibility genes for atherosclerosis. The screening process consisted of three steps. First, expression profiles of macrophages from subjects with atherosclerosis were compared to macrophages from control subjects. Secondly, the subjects were genotyped for promoter region polymorphisms in genes with altered gene expression. Thirdly, a population of subjects with coronary heart disease and control subjects were genotyped to test for an association with identified polymorphisms that affected gene expression. Twenty-seven genes were differentially expressed in both macrophages and foam cells from subjects with atherosclerosis. Three of these genes, IRS2, CD86 and SLC11A1 were selected for further analysis. Foam cells from subjects homozygous for the C allele at the -765C-->T SNP located in the promoter region of IRS2 had increased gene expression compared to foam cells from subjects with the nonCC genotype. Also, macrophages and foam cells from subjects homozygous for allele 2 at a repeat element in the promoter region of SLC11A1 had increased gene expression compared to macrophages and foam cells from subjects with the non22 genotype. Genotyping of 512 pairs of subjects with coronary heart disease (CHD) and matched controls revealed that subjects homozygous for C of the IRS2 SNP had an increased risk for CHD; odds ratio 1.43, p=0.010. Immunohistochemical staining of human carotid plaques showed that IRS2 expression was localised to macrophages and endothelial cells in vivo. Our method provides a reliable approach for identifying susceptibility genes for atherosclerosis, and we conclude that elevated IRS2 gene expression in macrophages may be associated with an increased risk of CHD.

Regulation of human aldoketoreductase 1C3 (AKR1C3) gene expression in the adipose tissue.

Aldoketoreductase 1C3 (AKR1C3) is a functional prostaglandin F synthase and a negative modulator of the availability of ligands for the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma). AKR1C3 expression is known to be associated with adiposity, one of the components of the metabolic syndrome. The aim of this study was to characterize the expression of AKR1C3 in the adipose tissue and adipocytes and to investigate its potential role in the metabolic syndrome. Using microarray analysis and realtime PCR, we studied the expression of AKR1C3 in adipose tissue samples from obese subjects with or without metabolic complications, during very low calorie diet-induced weight loss, and its expression in isolated human adipocytes of different sizes. The adipose tissue AKR1C3 expression levels were marginally lower in obese subjects with the metabolic syndrome compared with the levels in healthy obese subjects when analyzed using microarray (p = 0.078) and realtime PCR (p < 0.05), suggesting a secondary or compensatory effect. The adipose tissue mRNA levels of AKR1C3 were reduced during and after dietinduced weight-loss compared to the levels before the start of the diet (p < 0.001 at all time-points). The gene expression of AKR1C3 correlated with both adipose tissue mRNA levels and serum levels of leptin before the start of the diet (p < 0.05 and p < 0.01, respectively). Furthermore, large adipocytes displayed a higher expression of AKR1C3 than small adipocytes (1.5-fold, p < 0.01). In conclusion, adipose tissue AKR1C3 expression may be affected by metabolic disease, and its levels are significantly reduced in response to dietinduced weight loss and correlate with leptin levels.

The expression of NAD(P)H:quinone oxidoreductase 1 is high in human adipose tissue, reduced by weight loss, and correlates with adiposity, insulin sensitivity, and markers of liver dysfunction.

CONTEXT: We have previously identified nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase 1 (NQO1), an enzyme involved in the protection against oxidative stress, as a gene predominantly expressed in human adipocytes. Studies in mice deficient in NQO1 activity suggest that NQO1 may also play an important role in metabolism. OBJECTIVE: The aim of this study was to explore the expression and regulation of NQO1 in human adipose tissue (AT) and isolated adipocytes. PATIENTS AND RESULTS: The high expression of NQO1 in adipocytes was verified in human adipocytes and AT by real-time PCR. DNA microarray analysis showed that NQO1 was expressed at higher levels in large compared with small adipocytes, isolated from the same fat biopsy. Furthermore, NQO1 mRNA levels were positively correlated with adipocyte size (n = 7; P < 0.002). During an 18-wk diet regime (n = 24; mean weight loss 27 kg), the NQO1 expression in human sc AT was down-regulated (P < 0.0001), and mRNA levels correlated with body mass index (P = 0.0005), sc, and total abdominal AT areas, as determined by computerized tomography (P < 0.0001, both) and metabolic parameters. NQO1 mRNA levels were also positively correlated with aspartate aminotransferase (P = 0.0028) and alanine aminotransferase (P = 0.0219), markers known to be associated with severity of hepatic steatosis. CONCLUSIONS: NQO1 is highly expressed in human AT, particularly in large adipocytes. AT NQO1 expression is reduced during diet-induced weight loss, and the expression levels positively correlate with adiposity, glucose tolerance, and markers of liver dysfunction. Together, these findings indicate a role for NQO1 in the metabolic complications of human obesity.

Relations of adipose tissue CIDEA gene expression to basal metabolic rate, energy restriction, and obesity: population-based and dietary intervention studies.

CONTEXT: Cell death-inducing DNA fragmentation factor-alpha-like effector A (CIDEA) could be a potential target for the treatment of obesity via the modulation of metabolic rate, based on the findings that CIDEA inhibits the brown adipose tissue uncoupling process in rodents. OBJECTIVES: Our objects were to investigate the putative link between CIDEA and basal metabolic rate in humans and to elucidate further the role of CIDEA in human obesity. DESIGN: We have explored CIDEA gene expression in adipose tissue in two different human studies: a cross-sectional and population-based study assessing body composition and metabolic rate (Mölndal Metabolic study, n = 92); and a longitudinal intervention study of obese subjects treated with a very low calorie diet (VLCD) (VLCD study, n = 24). RESULTS: The CIDEA gene was predominantly expressed in adipocytes as compared with other human tissues. CIDEA gene expression in adipose tissue was inversely associated with basal metabolic rate independently of body composition, age, and gender (P = 0.014). The VLCD induced an increase in adipose tissue CIDEA expression (P < 0.0001) with a subsequent decrease in response to refeeding (P < 0.0001). Reduced CIDEA gene expression was associated with a high body fat content (P < 0.0001) and high insulin levels (P < 0.01). No dysregulation of CIDEA expression was observed in individuals with the metabolic syndrome when compared with body mass index-matched controls. In a separate sample of VLCD-treated subjects (n = 10), uncoupling protein 1 expression was reduced during diet (P = 0.0026) and inversely associated with CIDEA expression (P = 0.0014). CONCLUSION: The findings are consistent with the concept that CIDEA plays a role in adipose tissue energy expenditure.

Separation of human adipocytes by size: hypertrophic fat cells display distinct gene expression.

Enlarged adipocytes are associated with insulin resistance and are an independent predictor of type 2 diabetes. To understand the molecular link between these diseases and adipocyte hypertrophy, we developed a technique to separate human adipocytes from an adipose tissue sample into populations of small cells (mean 57.6+/-3.54 microm) and large cells (mean 100.1+/-3.94 microm). Microarray analysis of the cell populations separated from adipose tissue from three subjects identified 14 genes, of which five immune-related, with more than fourfold higher expression in large cells than small cells. Two of these genes were serum amyloid A (SAA) and transmembrane 4 L six family member 1 (TM4SF1). Real-time RT-PCR analysis of SAA and TM4SF1 expression in adipocytes from seven subjects revealed 19-fold and 22-fold higher expression in the large cells, respectively, and a correlation between adipocyte size and both SAA and TM4SF1 expression. The results were verified using immunohistochemistry. In comparison with 17 other human tissues and cell types by microarray, large adipocytes displayed by far the highest SAA and TM4SF1 expression. Thus, we have identified genes with markedly higher expression in large, compared with small, human adipocytes. These genes may link hypertrophic obesity to insulin resistance/type 2 diabetes.

Dissociation between adipose tissue expression and serum levels of adiponectin during and after diet-induced weight loss in obese subjects with and without the metabolic syndrome.

The study aimed to examine if dysmetabolic subjects (MetS+) have lower adiponectin gene expression and lower circulating adiponectin levels than non-dysmetabolic obese subjects (MetS-) at baseline, if adiponectin expression and adiponectin concentration rise more in the dysmetabolic group during weight loss, and if v-SNARE Vti1a (vesicle transport soluble NSF attachment protein receptor vps10p tail interacting 1a) expression increases during the weight loss, as a mechanism for increased adiponectin secretion. Twenty-one obese MetS+ and 19 obese MetS- subjects underwent a very low-energy diet for 16 weeks followed by 2 weeks of refeeding. Abdominal subcutaneous adipose tissue biopsies and blood samples were taken before, during, and after dieting for DNA microarray, reverse transcriptase-polymerase chain reaction, and biochemical analyses. Serum adiponectin was also assessed in a sex- and age-matched healthy, nonobese reference group. Weight decreased by 26.3+/-9.8 kg in the MetS+ group and 28.2+/-8.4 kg in the MetS- group with concomitant reductions in insulin, hemoglobin A1c, and triglycerides that were more pronounced in the MetS+ group. Initially, the MetS+ subjects had lower serum adiponectin, but the differences disappeared at week 8, with a continuous increase in serum adiponectin throughout the study in both groups to a level that was higher than in the reference group. The expression of adiponectin and v-SNARE Vti1a did not differ between the groups or over time. In conclusion, obese subjects with the metabolic syndrome had lower circulating adiponectin than subjects without the syndrome. Weight loss increased serum levels of adiponectin without a parallel increase in adiponectin gene expression. The mechanisms involved in the regulation of adiponectin levels merits further investigation.

Major role of HSP70 as a paracrine inducer of cytokine production in human oxidized LDL treated macrophages.

Lipid accumulation and inflammation are key hallmarks of the atherosclerotic plaque and macrophage uptake of oxidized low-density lipoprotein (oxLDL) is believed to drive these processes. Initial experiments show that supernatants from oxLDL treated macrophages could induce IL-1beta production in naïve macrophages. To search for potential paracrine mediators that could mediate this effect a DNA microarray scan of oxLDL treated human macrophages was performed. This analysis revealed that oxLDL induced activation of heat shock protein (HSP) expression. HSPs have been implicated in the development of atherosclerosis, but the exact mechanisms for this is unclear. Extracellular heat shock protein 70 (HSP70) has been shown to elicit a pro-inflammatory cytokine response in monocytes and could therefore be a potential paracrine pro-inflammatory mediator. After 24 h of oxLDL treatment there was a significant increase of HSP70 concentrations in supernatants from oxLDL treated macrophages (oxLDLsup) compared to untreated controls (P<0.05). OxLDLsup could induce both interleukin (IL)-1beta and IL-12 secretion in naïve macrophages. We also demonstrate that the effect of oxLDLsup on cytokine production and release could be blocked by inhibition of HSP70 transcription or secretion or by the use of HSP70 neutralizing antibodies. This suggests that extracellular HSP70 can mediate pro-inflammatory changes in macrophages in response to oxLDL.

Oxidized LDL induces a coordinated up-regulation of the glutathione and thioredoxin systems in human macrophages.

Using DNA microarray analysis, we found that human macrophages respond to oxidized low-density lipoprotein (oxLDL) by activating the antioxidative glutathione and thioredoxin systems. Several genes of the glutathione and thioredoxin systems were expressed at high levels in macrophages when compared to 80 other human tissues and cell types, indicating that these systems may be of particular importance in macrophages. The up-regulation of three genes in these systems, thioredoxin (P < 0.005), thioredoxin reductase 1 (P < 0.001) and glutathione reductase (P < 0.001) was verified with real-time RT-PCR, using human macrophages from 10 healthy donors. To investigate the possible role of these antioxidative systems in the development of atherosclerosis, expression levels in macrophages from 15 subjects with atherosclerosis (12 men, 3 women) and 15 matched controls (12 men, 3 women) were analyzed using DNA microarrays. Two genes in the glutathione system Mn superoxide dismutase (P < 0.05) and catalase (P < 0.05) differed in expression between the groups. We conclude that macrophage uptake of oxidized LDL induces a coordinated up-regulation of genes of the glutathione and thioredoxin systems, suggesting that these systems may participate in the cellular defense against oxidized LDL and possibly modulate the development of atherosclerosis.

Evaluation of CXCL9 and CXCL10 as circulating biomarkers of human cardiac allograft rejection.

BACKGROUND: Cardiac allograft rejection remains a significant clinical problem in the early phase after heart transplantation and requires frequent surveillance with endomyocardial biopsy. However, this is an invasive procedure, which is unpleasant for the patient and carries a certain risk. Therefore, a sensitive non-invasive biomarker of acute rejection would be desirable. METHODS: Endomyocardial tissue samples and serum were obtained in connection with clinical biopsies from twenty consecutive heart transplant patients followed for six months. A rejection episode was observed in 14 patients (11 men and 3 women) and biopsies obtained before, during and after the episode were identified. Endomyocardial RNA, from three patients, matching these three points in time were analysed with DNA microarray. Genes showing up-regulation during rejection followed by normalization after the rejection episode were evaluated further with real-time RT-PCR. Finally, ELISA was performed to investigate whether change in gene-regulation during graft rejection was reflected in altered concentrations of the encoded protein in serum. RESULTS: Three potential cardiac allograft rejection biomarker genes, chemokine (C-X-C motif) ligand 9 (CXCL9), chemokine (C-X-C motif) ligand 10 (CXCL10) and Natriuretic peptide precursor A (NPPA), from the DNA microarray analysis were selected for further evaluation. CXCL9 was significantly upregulated during rejection (p < 0.05) and CXCL10 displayed a similar pattern without reaching statistical significance. Serum levels of CXCL9 and CXCL10 were measured by ELISA in samples from 10 patients before, during and after cardiac rejection. There were no changes in CXCL9 and CXCL10 serum concentrations during cardiac rejection. Both chemokines displayed large individual variations in the selected samples, but the serum levels between the two chemokines correlated (p < 0.001). CONCLUSION: We conclude, that despite a distinct up-regulation of CXCL9 mRNA in human hearts during cardiac allograft rejection, this was not reflected in the serum levels of the encoded protein. Thus, in contrast to previous suggestions, serum CXCL9 does not appear to be a promising serum biomarker for cardiac allograft rejection.

Gene expression profiling of the rat hippocampus one month after focal cerebral ischemia followed by enriched environment.

Functional recovery after experimental stroke in rats is enhanced by environmental enrichment by stimulating plastic changes in brain regions outside the lesion, but the molecular mechanisms are not known. We investigated the effect of environmental enrichment after focal cerebral ischemia on cognitive recovery and hippocampal gene expression using microarray analysis. Rats placed in enriched environment (EE) for 1 month after middle cerebral artery occlusion (MCAo) showed significantly improved spatial memory in the Morris water maze compared to rats housed alone after MCAo. Microarray analysis suggested several EE-induced differences in neuronal plasticity-related genes, but these changes could not be confirmed by quantitative real-time PCR. This study highlights some of the potential problems associated with gene expression profiling of brain tissues. Further studies at earlier time points and in additional subregions of the brain are of interest in the search for molecular mechanisms behind EE-induced neuronal plasticity after ischemic stroke.