[Significance of anti-carbamylated fibrinogen antibodies in systemic lupus erythematosus].

OBJECTIVE: Antibodies against carbamylated protein (anti-CarP) were found to be a promising marker to evaluate joint damage and disease activity in patients with rheumatoid arthritis (RA). However, whether anti-CarP antibodies were present in systemic lupus erythematosus (SLE) remained ambiguity. We have therefore undertaken this study to assess the levels of serum anti-CarP antibodies and to evaluate their clinical value in SLE. METHODS: Serum levels of antibodies against carbamylatedfibrinogen (anti-CarP) were measured by enzyme-linked immunosorbent assay (ELISA) in 105 SLE patients and 73 healthy controls. Other clinical and laboratory measurements of the SLE patients were collected from medical records. Data analyses between anti-CarP antibodies and other laboratory measurements were performed using SPSS software for Windows 24.0. RESULTS: The levels of serum anti-CarP antibodies in the patients with SLE were significantly higher than those in the healthy controls (P<0.05). There were significant differences between the anti-CarP-positive group and anti-CarP-negative group in many clinical features. The disease duration, values of ESR, CRP, RF, anti-cardiolipin, anti-dsDNA, D-dipolymer, IgA and IgG were significantly higher in the anti-CarP-positive group compared with the negative group (P<0.05). Conversely, the values of complement 3, complement 4, peripheral blood RBC, and hemoglobin were significantly lower in anti-CarP-positive group than in the negative group(P<0.05). Moreover, the incidence of increase of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), D-dipolymer, decrease of peripheral blood RBC, hemoglobin, complement 3, complement 4, and positive rate of anti-dsDNA were significant different between the two groups(P<0.05). The positive rate of anti-CarP (21.9%) was higher than that of anti-Sm (15.24%), and close to anti-ribosomal P protein (22.86%) in our SLE patients. In addition, anti-CarP antibody was present in the SLE patients lacking the disease specific antibodies, including anti-Sm (anti-CarP positive rate 20.2%, 18/89), anti-dsDNA (anti-CarP positive rate 9.3%, 4/43), anti-nucleosome (anti-CarP positive rate 12.5%, 6/48), and anti-ribosomal P protein antibody (anti-CarP positive rate 20.9%, 17/81). Moreover, the high levels of anti-CarP antibodies were correlated with short disease duration, low C3, C4, RBC, and hemoglobin (P<0.05), high ESR, CRP, IgA, IgG, RF, anti-cardiolipin, anti-dsDNA, and D-dipolymer (P<0.05). CONCLUSION: The level of anti-CarP antibody was increased in the serum of patients with SLE. There were correlations between anti-CarP antibodies and clinical and laboratory indicators of SLE patients.

Targeted disruption of the catalytic subunit of the DNA-PK gene in mice confers severe combined immunodeficiency and radiosensitivity.

The DNA-dependent protein kinase is a mammalian protein complex composed of Ku70, Ku80, and DNA-PKcs subunits that has been implicated in DNA double-strand break repair and V(D)J recombination. Here, by gene targeting, we have constructed a mouse with a disruption in the kinase domain of DNA-PKcs, generating an animal model completely devoid of DNA-PK activity. Our results demonstrate that DNA-PK activity is required for coding but not for signal join formation in mice. Although our DNA-PKcs defective mice closely resemble Scid mice, they differ by having elevated numbers of CD4+CD8+ thymocytes. This suggests that the Scid mice may not represent a null phenotype and may retain some residual DNA-PKcs function.

Characterization of a sodium-response transcriptional mechanism.

On the basis of paradigms in development wherein discrete transcriptional events are pivotal regulatory steps, we tested the hypothesis that transcriptional sodium (Na+)-response mechanisms are involved in in vivo Na+-induced responses relevant to normal (homeostatic) and pathophysiological (salt-sensitive hypertension) conditions. We used Na,K-ATPase alpha-subunit genes as molecular probes and the Na+ ionophore monensin to induce a dose-specific incremental increase in [Na+]i in rat A10 embryonic aortic smooth muscle cells. RNA blot analysis of rat A10 cells revealed a dose-specific (0.022 to 30 micromol/L monensin) upregulation of alpha1-, alpha2-, and beta1-subunit Na,K-ATPase RNA levels. Control beta-actin and alpha-tropomyosin RNA levels did not change. With the use of chloramphenicol acetyltransferase (CAT) as reporter gene, CAT assays of rat alpha1[-1288]CAT and human alpha2[-798]CAT promoter constructs exhibited induction of CAT activity in monensin (10 micromol/L)-treated A10 cells compared with untreated A10 cells. Promoter deletion constructs for rat alpha1[-1288]CAT defined a positive Na+-response regulatory region within -358 to -169 that is distinct from the basal transcriptional activation region of -155 to -49 previously defined. Similarly, a positive Na+-response regulatory region is delimited to within -301 in the human alpha2 Na,K-ATPase 5' flanking region. Analysis of transgenic TgH alpha2[-798]CAT rats demonstrated sodium activation of human alpha2[-798]CAT transgene expression in aorta parallel to observations made in rat A10 aortic tissue culture cells. Southwestern blot analysis of nuclear extracts from monensin (10 micromol/L)-treated and control untreated A10 cells revealed a nuclear DNA binding protein (approximately 95 kD) that is upregulated by increased [Na+]i. These data provide initial characterization of a transcriptional Na+-response mechanism delimiting a positive Na+-response regulatory region in two target genes (alpha1 and alpha2 Na,K-ATPase) as well as detection of a Na+-response nuclear DNA binding protein. The in vitro data are corroborated by in vivo experimental and transgenic promoter expression studies, thus validating the biological relevance of the observations.

Pressure-overload deinduction of human alpha 2 Na,K-ATPase gene expression in transgenic rats.

The early and sustained deinduction of alpha 2 Na,K-ATPase gene expression in both cardiac left ventricle and aorta in various pressure-overload rat models and in hypertrophied human heart suggests a common transcriptional pressure response mechanism to pressure overload in both rats and humans. To test this hypothesis, we developed transgenic rat lines expressing the chloramphenicol acetyltransferase reporter gene regulated by the human alpha 2 Na,K-ATPase (-798 to +67) regulatory region, H alpha 2-CAT. Analysis of two homozygous transgenic rat lines revealed (1) parallel tissue-specific regulation of the H alpha 2-CAT transgene and rat alpha 2 Na,K-ATPase gene and (2) parallel load-induced deinduction of both cardiac and vascular (aortic) H alpha 2-CAT transgene and rat alpha 2 Na,K-ATPase gene expression in a 3-day model of induced pressure overload. Cardiac H alpha 2-CAT deinduction was detected at a systolic pressure greater than or equal to 150 mm Hg and correlated with the degree of systolic pressure elevation (r = .82, P < .0001). The data suggest a systolic pressure gradient-dependent coordinate pressure-overload transcriptional response mechanism in the heart and aorta, with one of its target genes being the alpha 2 Na,K-ATPase gene in both humans and rats.