Biomedical subjects

Carlos E Alvarez

Publications and source records attributed to Carlos E Alvarez.

8 recordsLinked to original sources

PubMed2006

Beneficial effect of glatiramer acetate (Copaxone) on immune modulation of experimental hepatic fibrosis.

While CD8 subsets activate hepatic fibrosis, natural killer (NK) cells exhibit antifibrotic activity. Glatiramer acetate (GA) is an immune modulator for multiple sclerosis. We assessed the potential impact of GA on mouse hepatic fibrogenesis. Hepatic fibrosis was induced in C57BL/6 mice by intraperitoneal administration of carbon tetrachloride (CCl(4)) for 6 wk. During the last 2 wk, animals were also treated with either GA (200 mu/day ip) or medium and compared with naive and fibrotic mice (8 animals/group). GA markedly attenuated fibrosis without altering reactive oxygen species production. By morphometric measurement of Sirius red-stained tissue sections, the relative fibrosis area decreased from 5.28 +/- 0.32% (mean +/- SE) in the untreated CCl(4) group to 2.01 +/- 0.28% in CCl(4)+GA-treated animals, compared with 0.38 +/- 0.07% in naive mice. alpha-Smooth muscle actin immunoblotting and mRNA expression revealed a similar pattern. Serum aminotransferase and Ishak-Knodell necroinflammatory score were markedly elevated, to the same extent, in both CCl(4)-treated groups. Fibrosis induction was associated with significant increase in CD8 subsets and decrease in CD4 T cells. After GA treatment, however, NK content, CD4(+)CD25(+)FoxP3(+) cells, hepatic expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and apoptosis of hepatic stellate cells were all increased. Serum interleukin (IL)-10 levels markedly rose, whereas IL-4 fell. In vitro activation of human hepatic stellate cells cocultured with hepatitis C virus-derived peripheral blood lymphocytes decreased when lymphocytes were preincubated with GA before coculture. In an animal model of hepatic fibrosis, GA has an antifibrotic effect associated with decreased CD8 cells and reduced serum IL-4 levels and increased NK cells, CD4(+)CD25(+)FoxP3(+) cells, TRAIL, and elevated serum IL-10 levels.

Actins↗

PubMed2006

Anti-fibrotic activity of NK cells in experimental liver injury through killing of activated HSC.

BACKGROUND/AIMS: We have investigated the role of natural killer (NK) cells in hepatic fibrogenesis. Mouse NK cells express both inhibitory/activating-killing-immunoglobulin-related-receptors (iKIR/aKIR) specific for Class-I-molecules. METHODS: Hepatic fibrosis induced by carbon-tetrachloride (CCl4) was compared between wild-type (WT) male-BALBc; combined-immunodeficiency (SCID, lacking B/T-cells); and SCID-BEIGE-mice (lacking B/T/NK cells), and naive mice. RESULTS: Hepatic fibrosis significantly increased in all CCl4-treated groups. SCID-BEIGE mice had more fibrosis than SCID-mice (P<0.0001) as assessed by morphometry of sirius-red stained tissue sections. Following fibrosis, hepatic NK cells significantly decreased, the aKIR:iKIR-ratio significantly increased while Class-I expression on HSC decreased (P<0.001). Both freshly isolated and in situ HSC displayed a significant increase in cellular apoptosis following fibrosis induction. Confocal microscopy demonstrated the direct adhesion of NK cells to HSC in mouse liver sections and in vitro human NK/HSC co-culture. In human HSC there was decreased Class-I expression and increased apoptosis as well, which was further increased following blocking of either HSC-related Class-I or NK-related killer inhibitory receptors. Apoptosis was inhibited by pre-incubation of NK cells with the granzyme inhibitor 3,4-dichloroisocoumarin. CONCLUSIONS: During liver injury, NK cells have an anti-fibrotic activity at least in part through stimulation of HSC killing.

Actins↗

PubMed2006

Epigenomics: mapping the methylome.

DNA methylation is integral to normal development and disease processes. However, the genomic distribution of methylated sequences--the methylome--is poorly understood. We have recently developed a platform technology for rapid assessment of methylation status throughout the human genome in a high-resolution, high-throughput manner. This is achieved by coupling a methylated DNA immunoprecipitation (MeDIP) method for isolating methyl cytosine rich fragments with array-based comparative genomic hybridization (array CGH). Using a combination of whole genome tiling path BAC arrays and CpG island microarrays, DNA methylation profiles are obtained simultaneously at both genome-wide and locus-specific levels. A comparison between male and female DNA using MeDIP-array CGH revealed unexpected hypomethylation of the inactive x-chromosome in gene-poor regions. Furthermore, comparisons between cancer and noncancer cell types yielded differential methylation patterns that link genetic and epigenetic instability offering a new approach to decipher misregulation in cancer. Finally, we provide new data showing epigenomic instability in lung cancer cells with concurrent regions of genetic and epigenetic alterations harboring known oncogenes.

Chromatin Immunoprecipitation↗

PubMed2005

Enhanced oral tolerance in transgenic mice with hepatocyte secretion of IL-10.

Several cytokines derived from Th3 and Tr1 cells, including IL-10, are believed to regulate oral tolerance, but direct evidence is lacking. We have explored the potential role of IL-10 by generating transgenic (TG) mice with sustained hepatocyte-specific expression of rat IL-10. TG mice expressed rat IL-10 downstream of a transthyretin promoter, which led to serum levels that were increased 10- to 100-fold compared with normal animals. Animals were orally administered 1 mg of whole OVA for 5 consecutive days, with control animals receiving PBS. There were six animal groups: Either OVA or PBS were fed orally to rat IL-10 TG mice, non-TG wild-type mice without IL-10 administration, and non-TG wild-type mice administered rat IL-10 systemically. On day 8, all mice were immunized with two injections of OVA, and then analyzed on day 18. T cell proliferation responses were reduced by 65.8 +/- 14.3% after feeding of OVA in rIL-10 TG animals, compared with 39.4 +/- 15.6% in the non-TG mice (p = 0.02). Anti-OVA titers were expressed as fold increase over naive non-TG mice. After feeding, titers decreased by approximately 33% (from 3- to 2-fold) in TG animals and, to a lesser extent, in non-TG animals. IFN-gamma secretion by cultured popliteal lymphocytes decreased in TG animals by 83% after feeding and by 69% in non-TG animals. IL-4 secretion increased 4-fold in TG-fed mice, but did not significantly change in non-TG OVA-fed animals. In contrast to hepatic TG expression of rIL-10, systemic administration of rIL-10 had only a modest effect on tolerance. IL-10, when transgenically expressed in the liver enhances mucosal tolerance to an oral Ag.

Administration, Oral↗

PubMed2005

Interleukin-6 protects hepatocytes from CCl4-mediated necrosis and apoptosis in mice by reducing MMP-2 expression.

BACKGROUND/AIMS: Interleukin-6 stimulates liver regeneration and promotes hepatoprotection following experimental liver injury, but underlying mechanisms have not been fully characterized. Because studies suggest matrix metalloproteinase-2 (MMP-2) may promote liver injury, we examined whether IL-6 exerted its protective effects via regulation of MMP-2. METHODS: MMP-2 was analyzed in livers of IL-6-/- and IL-6+/+ mice following CCl(4) administration. IL-6-/- mice were pretreated with IL-6 and liver histology and MMP-2 expression were examined after liver injury. IL-6-/- mice were treated with an MMP-2 inhibitor and assessment of injury (histology and serum ALT levels), apoptosis by TUNEL assay, and hepatocyte proliferation by BRDU-labeling was performed. These studies were complemented by analysis of cultured stellate cells. RESULTS: MMP-2 mRNA, protein, and activity was increased in IL-6-/- livers. Restoration of IL-6 signaling in IL-6-/- mice rescued injury and restored MMP-2 expression to wild-type levels. Furthermore, pharmacologic inhibition of MMP-2 decreased hepatocellular injury and apoptosis in IL-6-/- mice. In cultured stellate cells, recombinant IL-6 suppressed endogenous MMP-2 mRNA and protein expression. CONCLUSIONS: IL-6 may be hepatoprotective in acute injury through down-regulation of MMP-2. These findings suggest a role for MMP-2 in amplifying liver injury in vivo.

Acute Disease↗

PubMed2004

Immune stimulation of hepatic fibrogenesis by CD8 cells and attenuation by transgenic interleukin-10 from hepatocytes.

BACKGROUNDS & AIMS: Immunomodulatory cytokines, including interleukin-10 (IL-10), may mediate hepatic fibrosis. METHODS: We generated transgenic (TG) mice with hepatocyte expression of rat IL-10 (rIL-10) to assess its impact on lymphocyte subsets and activation of hepatic stellate cells following liver injury from carbon tetrachloride (CCl 4 ) or thioacetamide (TAA). RESULTS: Fibrosis was reduced in the TG animals in both models, which was not explained solely by differences in liver injury. By fluorescence-activated cell sorter (FACS), there were less CD4+ T cells in naive TG mice, and, following fibrosis induction, CD4+ T cells decreased only in wild-type (WT) mice, whereas increases in CD8+ T cells seen in WT animals were significantly attenuated in TG mice. Subtotal irradiation diminished fibrosis equally in both WT and TG groups, suggesting that rIL-10's antifibrotic effect was lymphocyte mediated. To assess the role of lymphocytes on stellate cell activation, either whole splenic lymphocytes, CD4+, or CD8+ T-cell subsets from WT animals with CCl 4 fibrosis were adoptively transferred to severe combined immunodeficiency (SCID) recipients, which led to stellate cell activation and fibrogenic stimulation as assessed by expression of transforming growth factor (TGF)-beta1 and collagen I messenger RNA (mRNA) and by immunoblot of alpha-smooth muscle actin. Moreover, serum aminotransferase levels and stellate cell activation mRNA were significantly higher among the CD8+ T-cell recipients. CONCLUSIONS: Transgenic expression of rIL-10 in liver leads to reduced fibrosis and alterations in liver lymphocyte subsets both in untreated liver and following fibrosis induction. In this model, fibrosis may be a CD8+ T-cell-mediated disease that is attenuated by rIL-10.

Adoptive Transfer↗

PubMed2002

Hypocretin is an early member of the incretin gene family.

Recent studies have revealed that the hypothalamic hypocretin (Hcrt) neuropeptide system is centrally involved in mammalian REM sleep and that it may have other diverse physiological roles. The aims of this work were to learn when HCRT emerged and to test our previous hypothesis that it was created by a circular permutation of an incretin superfamily gene. We found HCRT in fish and believe the gene arose approximately 650 million years ago, in the early chordate lineage. Our comparison of Hcrts to the most similar members of the incretin peptide superfamily leads us to conclude that HCRTs are indeed incretin paralogs that arose by a genetic circular permutation.

Animals↗

PubMed2002

Novel isoform of insulin receptor substrate p53/p58 is generated by alternative splicing in the CRIB/SH3-binding region.

Insulin receptor substrate p53/p58 (IRSp53) is involved in cytoskeletal dynamics and is a candidate disease sensor in polyglutamine expansion neurodegeneration. It is widely expressed throughout the body, but its levels are dramatically elevated in forebrain regions. IRSp53 functions as a signal transducing adaptor between activated Rho family GTPases and their effectors. There are four known alternatively spliced isoforms of IRSp53 that vary by the identity of the 3'-terminal exon. We report here that there is a fifth alternatively spliced isoform, IRSp53-B, which lacks 40 amino acids abutting the CRIB/SH3 (Cdc42/Rac-interactive binding/Src homology 3)-binding site. We speculate that the novel form has an altered function related to the mechanism of autoinactivation. IRSp53-B has an odd history in the mammalian lineage, which may complicate the use of rodent models to study cytoskeletal reorganization.

Alternative Splicing↗