An antibody that inhibits TGF-ß1 release from latent extracellular matrix complexes attenuates the progression of renal fibrosis.

Inhibitors of the transforming growth factor-ß (TGF-ß) pathway are potentially promising antifibrotic therapies, but nonselective simultaneous inhibition of all three TGF-ß homologs has safety liabilities. TGF-ß1 is noncovalently bound to a latency-associated peptide that is, in turn, covalently bound to different presenting molecules within large latent complexes. The latent TGF-ß-binding proteins (LTBPs) present TGF-ß1 in the extracellular matrix, and TGF-ß1 is presented on immune cells by two transmembrane proteins, glycoprotein A repetitions predominant (GARP) and leucine-rich repeat protein 33 (LRRC33). Here, we describe LTBP-49247, an antibody that selectively bound to and inhibited the activation of TGF-ß1 presented by LTBPs but did not bind to TGF-ß1 presented by GARP or LRRC33. Structural studies demonstrated that LTBP-49247 recognized an epitope on LTBP-presented TGF-ß1 that is not accessible on GARP- or LRRC33-presented TGF-ß1, explaining the antibody's selectivity for LTBP-complexed TGF-ß1. In two rodent models of kidney fibrosis of different etiologies, LTBP-49247 attenuated fibrotic progression, indicating the central role of LTBP-presented TGF-ß1 in renal fibrosis. In mice, LTBP-49247 did not have the toxic effects associated with less selective TGF-ß inhibitors. These results establish the feasibility of selectively targeting LTBP-bound TGF-ß1 as an approach for treating fibrosis.

High serum Abeta and vascular risk factors in first-degree relatives of Alzheimer's disease patients.

The main objective of this study was to determine whether elevated blood beta-amyloid (Abeta) levels among the first-degree relatives of patients with Alzheimer's Disease (AD) are associated with vascular risk factors of AD. Serum Abeta was measured in samples from 197 cognitively normal first-degree relatives of patients with AD-like dementia. Study participants were recruited as part of an ancillary study of the Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT subpopulation). The ADAPT subpopulation was found to be similar in age, sex, and ethnicity to another cognitively normal cohort (n = 98). Using cross-sectional analyses, we examined the association of Abeta with blood pressure, lipid levels, apolipoprotein E genotypes, and the use of prescribed medication to treat vascular risk factors in the ADAPT subpopulation. Abeta(1-40) was positively associated with age, use of antihypertensives, and serum creatinine, and we observed a marginal negative interaction on Abeta(1-40) associated with systolic blood pressure and use of antihypertensives. Serum Abeta(1-42) was associated with statin use and a positive correlation of Abeta (1-42) with HDL was observed among statin nonusers. These findings suggest that high Abeta in the periphery among the family history-enriched cohorts may be due to enrichment of vascular risk factors and may reflect presymptomatic AD pathology. It remains to be determined whether the association of Abeta with medications used for treating vascular risk factors indicates prevention of AD. Longitudinal evaluation of blood Abeta in this cohort will provide a better understanding of the significance of this association in AD etiology.

CD40 ligation mediates plaque-associated tau phosphorylation in beta-amyloid overproducing mice.

Neuritic dystrophy with amyloid burden and neurofibrillary tangles are pathological hallmarks of Alzheimer's disease. Genetic disruption of CD40 or CD40L alleviates amyloid burden, astrocytosis, and microgliosis in transgenic animal models of Alzheimer's disease. It has been reported that phosphorylated tau-positive dystrophic neurites are observed in transgenic mice over-expressing human mutant beta-amyloid precursor protein (Tg2576). Here, we studied the pattern of phosphorylated tau (labeled with AT8, CP13, PG5, and PHF1 antibodies) and plaques using immunohistochemical techniques. Phosphorylated tau-positive dystrophic neurites were exclusively associated with Congo red-positive plaques as previously reported. Further, we show that CD40L or CD40 deficiency reduces the mean ratio of dystrophic neurite area to congophilic plaque area and the level of expression of cdk5 and p35/p25 in mice. In addition, we show that in a human neuroblastoma cell line treated with CD40L, cdk5 and p35/p25 are increased. Together, our data suggest that CD40-CD40L interaction has an effect on tau phosphorylation independent of beta-amyloid pathology, and that this effect may occur through a decrease of cdk5 and p35/p25.

Genomic analysis of response to traumatic brain injury in a mouse model of Alzheimer's disease (APPsw).

Numerous studies have shown that the beta-amyloid peptide (Abeta) or beta-amyloid deposits impact many processes that can contribute to neurodegeneration, ranging from immune and inflammatory processes to cell death and apoptosis, processes characteristic of both Alzheimer's disease and head injury. Human and animal studies of traumatic brain injury (TBI) have shown that Abeta production is increased acutely following injury, and there is evidence for increased amyloid deposition and risk for Alzheimer's disease following TBI. Given the poorer outcome after injury observed both in transgenic mice overproducing Abeta, as well as in humans subjected to repetitive head injury, one may conclude that the presence of elevated brain levels of Abeta, whether endogenous or as a consequence of previous injury, exacerbates many of the deleterious processes triggered by TBI. We sought to test this hypothesis by examining the genomic response to injury in wild-type mice and in transgenic mice (APPsw) overexpressing and accumulating cerebral Abeta/beta-amyloid. Gene expression was investigated by microarray 24 h after controlled cortical impact (CCI) injury or sham injury in aged APPsw transgenic mice and wild-type controls. Stringent statistical analysis revealed differential expression of a total of 129 genes in the transgenic TBI vs. sham comparison and 119 genes in the wild-type TBI vs. sham comparison. Of these, only 28 genes were common to both comparisons, suggesting considerable differences in response to injury in the Alzheimer models compared to wild-type mice. We focused our analyses by creating a "genotype-dependent" data set of response to injury which contained the genes that were uniquely altered in response to injury in either wild-type or APPsw mice, as well as those which were significantly differently modulated following TBI in one genotype compared to the other. The cellular functions predicted to be influenced by these changes in gene expression thus indicate the adverse pathways triggered by increased levels of Abeta, and the potentially favorable (recovery) pathways which are activated in wild-type mice but suppressed when Abeta levels are high. The results show that the cellular functions most influenced by the cerebral Abeta levels following TBI include inflammation, immune response, and cell death, which suggest a particular vulnerability to head injury in the Alzheimer brain.

Cocaine induced inflammatory response in human neuronal progenitor cells.

We have employed a genomic approach in homogenous cell culture to investigate the fundamental transcriptional responses which occur in neurons over time as a consequence of a single 30-min exposure to cocaine. Data from 24 Affymetrix microarrays, representing eight treatment groups, were analyzed by GeneChip Operating Software and then further mined by hierarchical clustering, anova, and Ingenuity Pathway Analysis software to examine known molecular pathways impacted by the observed transcriptional changes. For each time point under investigation, the data sets of genes exhibiting altered expression in treated cells compared with control were interrogated with a specific focus on differential expression of genes involved in immunomodulation and inflammation. The existing literature on the effects of cocaine in a diverse array of experimental paradigms demonstrates a significant modulation of inflammation and immune mechanisms, but these have typically been studies of chronic exposure in immune-competent cells. Our data show a time-dependent up-regulation of genes associated with pro-inflammatory and immune responses, peaking at 24 h as confirmed by all methods of analysis, suggesting a specific neuronal immunomodulatory response to acute cocaine exposure.

Estradiol represses prolactin-induced expression of Na+/taurocholate cotransporting polypeptide in liver cells through estrogen receptor-alpha and signal transducers and activators of transcription 5a.

Na(+)/taurocholate cotransporting polypeptide (ntcp) mediates the uptake of bile salts from plasma across the basolateral domain of the hepatocyte. We have demonstrated that ntcp expression can be induced by prolactin (PRL) and placental lactogen via the PRL receptor and signal transducers and activators of transcription (Stat)5a pathway. However, elevated levels of placental lactogen do not increase the expression of ntcp in pregnant rats. Because plasma estradiol (E(2)) levels are also elevated in pregnancy, we investigated the inhibitory effects of E(2) on PRL-induced ntcp activation. E(2) treatment inhibited the PRL-induced increase in liver ntcp mRNA to the same levels as in rats treated with E(2) alone. Estrogen receptor-alpha (ERalpha) mRNA and protein expression in liver were increased 2.6-fold and 2.2-fold, respectively, in pregnancy relative to controls. In HepG2 cells, E(2) repressed PRL-induced ntcp reporter gene expression in a dose-dependent manner in the presence of cotransfected ERalpha. The ERalpha antagonist ICI 182,780 reversed E(2)-induced repression, indicating specificity of inhibition by E(2). Overexpression of coactivator p300 did not reverse the inhibitory effects of E(2) and ERalpha. Western and gel shift analysis revealed that E(2)-bound ERalpha decreased the tyrosine phosphorylation and DNA-binding activity of Stat5a, indicating that the inhibitory effect of E(2) was mediated, at least in part, by interfering with PRL-mediated signal transduction. The present studies demonstrate the physiological significance of cross-talk between ERalpha and Stat5a in liver, in which both proteins are expressed. These data also establish a novel mechanism by which expression of ntcp, an important hepatic bile acid transporter, can be regulated by multiple hormones.

Biliary secretion of glutathione in estradiol 17beta-D-glucuronide-induced cholestasis.

Estradiol-17beta-D-glucuronide (E2-17G) induces an acute but reversible inhibition of bile flow after its intravenous administration to rats, due in part to the endocytic retrieval of the canalicular multidrug resistance-associated transporter protein 2 and the bile salt export pump, transporters that contribute to bile flow. Decreased bile salt-independent bile flow (BSIF) is also involved and persists during the phase of recovery from cholestasis. Because glutathione and HCO3- are major contributors to BSIF, we evaluated changes in their biliary excretion and the hepatic content of total glutathione during E2-17G-induced cholestasis. E2-17G acutely decreased bile flow and biliary excretion of total glutathione by about 80%; glutathione excretion was still inhibited at 80 min and 120 min, even though bile flow was partially and totally restored, respectively. Neither liver glutathione content nor the proportions of oxidized glutathione in bile and liver were affected by E2-17G at any time. HCO3- concentrations in bile were unchanged, so that secretion paralleled variations in bile flow. In the isolated perfused liver, addition of E2-17G decreased both bile flow and the biliary concentration of glutathione, whereas addition of its noncholestatic isomer estradiol-3-D-glucuronide (E2-3G) did not inhibit bile flow, but significantly reduced the concentration of glutathione in bile. The bile:liver concentration ratios of glutathione were significantly decreased in vivo by E2-17G and in the perfused liver by E2-17G and E2-3G. These data indicate that E2-17G cis-inhibits the canalicular transport of glutathione and thus contributes to the cholestatic effect by inhibiting BSIF.