Flora Zavala

Increase in IL-6, IL-1 and TNF levels in rat brain following traumatic lesion: Influence of pre- and post-traumatic treatment with Ro5 4864, a peripheral-type (p site) benzodiazepine ligand

The effects of fluid percussion trauma on brain interleukin (IL)-6, IL-1 and tumor necrosis factor-alpha (TNF-alpha) levels have been studied. In the cortex and hippocampus of control and sham-operated rats, the levels of these cytokines were very low (below 4 units/mg protein) and constant. IL-6 and IL-1 levels in the ipsilateral cortex increased rapidly following trauma to reach a maximum of 350 and 16 units/mg protein, respectively, 8 h after the lesion, remained elevated until 18 h and decreased thereafter to basal values. TNF-alpha levels were maximally elevated (12 units/mg protein) at 3 h and 8 h and returned to basal values by 18 h. Qualitatively similar changes, but with 25-80-fold smaller amplitude, were seen in the contralateral cortex and in the ipsi- and contralateral hippocampus. The levels of IL-6 in the plasma of sham-operated and lesioned rats were only slightly elevated, whereas IL-1 and TNF-alpha were undetectable. Histological studies of brain tissue at early stages after trauma demonstrated an acute hemorrhage associated with neutrophil invasion. The administration of Ro5 4864 (0.5 mg/kg i.p.), a specific ligand of p (peripheral-type benzodiazepine) binding sites, did not result in any significant effect on the levels of IL-6, IL-1 or TNF-alpha in the brain of control or sham-operated animals. However, when administered 24 h before or 15 min after trauma, this benzodiazepine enhanced the increase of these cytokines by 2-4-fold in the ipsilateral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Soluble tumor necrosis factor receptors in chronic hepatitis C: a correlation with histological fibrosis and activity.

BACKGROUND/AIMS Tumor necrosis factor-alpha (TNF) is a mediator of inflammation and cellular immune response. Soluble TNF receptors (sTNFR) sTNF-R55 and sTNF-R75, which compete with cellular receptors for the binding of TNF, have been detected at high levels in infectious diseases including human immunodeficiency virus and HBV infection. In order to investigate the activation of the TNF system in HCV infection, we have analyzed the balance between TNF and sTNF-R in 60 HCV-infected subjects according to their clinical, biological, virological and histological characteristics. METHODS Serum TNF, sTNF-R55 and sTNF-R75 levels were determined by ELISA before any therapy and were compared to a control group of 60 healthy subjects and a group of 34 HBV-infected patients. RESULTS Mean TNF levels were 50.5+/-4.5 pg/ml in HCV patients, and undetectable (<5 pg/ml) in the control subjects. sTNF-R55 and sTNF-R75 levels were significantly higher in HCV-infected patients than in the controls: 2.88+/-0.14 ng/ml vs. 1.30+/-0.05, (p = 0.0001), and 9.54+/-0.58 ng/ml vs. 4.19+/-016, (p = 0.0001), respectively. sTNF-R55 and TNF-alpha levels in HCV patients were not significantly different from levels in HBV patients. sTNF-R75 levels were slightly lower than in HBV patients (9.54+/-0.58 vs. 11.4+/-0.79 ng/ml, p = 0.03). In contrast to other infectious diseases, there was no correlation between levels of sTNF-R and TNF. sTNF-R75 but not TNF levels were correlated with aminotransferases levels (p = 0.0001 and p = 0.0015 for aspartate and alanine aminotransferase, respectively), while sTNF-R55 levels were significantly correlated only with aspartate aminotransferase levels (p = 0.003). sTNF-R75 levels were significantly correlated with the Metavir activity index (p = 0.01), and sTNF-R55 and sTNF-R75 levels were significantly higher in patients with vs. without cirrhosis (3.22+/-0.21 vs. 2.54+/-0.17 ng/ml (p<0.02) and 11.6+/-0.86 vs. 7.5+/-0.53 ng/ml (p<0.001), respectively). sTNF-R55, sTNF-R75 and TNF levels were not correlated with viral load, genotype or response to interferon therapy. CONCLUSIONS Levels of soluble TNF receptors, and particularly sTNF-R75, are significantly correlated with the severity of the disease but not with virological parameters such as quantitative viremia and genotype. High TNF-R production could thus suggest that HCV-related liver disease involves immunological mechanisms, including activation of the TNF system.

G-CSF Therapy of Ongoing Experimental Allergic Encephalomyelitis Via Chemokine- and Cytokine-Based Immune Deviation

Converging evidence that G-CSF, the hemopoietic growth factor of the myeloid lineage, also exerts anti-inflammatory and pro-Th2 effects, prompted us to evaluate its direct therapeutic potential in autoimmune diseases. Here we report a novel activity of G-CSF in experimental allergic encephalomyelitis, a murine model for multiple sclerosis, driven by Th1-oriented autoaggressive cells. A short 7-day treatment with G-CSF, initiated at the onset of clinical signs, provided durable protection from experimental autoimmune encephalomyelitis. G-CSF-treated mice displayed limited demyelination, reduced recruitment of T cells to the CNS, and very discrete autoimmune inflammation, as well as barely detectable CNS mRNA levels of cytokines and chemokines. In the periphery, G-CSF treatment triggered an imbalance in the production by macrophages as well as autoreactive splenocytes of macrophage inflammatory protein-1α and monocyte chemoattractant protein-1, the prototypical pro-Th1 and pro-Th2 CC chemokines, respectively. This chemokine imbalance was associated with an immune deviation of the autoreactive response, with reduced IFN-γ and increased IL-4 and TGF-β1 levels. Moreover, G-CSF limited the production of TNF-α, a cytokine also associated with early CNS infiltration and neurological deficit. These findings support the potential application of G-CSF in the treatment of human autoimmune diseases such as multiple sclerosis, taking advantage of the wide clinical favorable experience with this molecule.

Alcohol and hepatitis C virus core protein additively increase lipid peroxidation and synergistically trigger hepatic cytokine expression in a transgenic mouse model

BACKGROUND/AIMS Alcohol consumption accelerates the appearance of liver fibrosis and hepatocellular carcinoma in patients with chronic hepatitis C virus (HCV) infection, but the mechanisms of these interactions are unknown. We therefore investigated the effects of chronic ethanol consumption in HCV core protein-expressing transgenic mice. METHODS Ethanol was progressively added (up to 20%) to the drinking water that was given ad libidum. RESULTS In vivo fatty acid oxidation was not inhibited by ethanol consumption and/or HCV core expression. Both chronic ethanol consumption and HCV core expression decreased hepatic lipoprotein secretion and caused steatosis, but had no additive effects on lipoprotein secretion or steatosis. However, chronic ethanol consumption and HCV core protein additively increased lipid peroxidation and acted synergistically to increase the hepatic expression of transforming growth factor-beta (TGF-beta) and, to a less extent, tumor necrosis factor-alpha (TNF-alpha). CONCLUSIONS HCV core protein expression and chronic alcohol consumption have no effects on in vivo fatty acid oxidation and do not additively impair hepatic lipoprotein secretion, but additively increase hepatic lipid peroxidation and synergistically increase hepatic TNF-alpha and TGF-beta expression. These effects may be involved in the activation of fibrogenesis and the development of hepatocellular carcinoma in patients cumulating alcohol abuse and HCV infection.

The expression of hepatitis B spliced protein (HBSP) encoded by a spliced hepatitis B virus RNA is associated with viral replication and liver fibrosis

BACKGROUND/AIMS We have previously demonstrated the in vivo expression of a new spliced hepatitis B virus (HBV) protein (HBSP) encoded by a singly spliced pregenomic RNA. The present study was designed to evaluate the impact of HBSP expression on the clinical status and liver pathology of HBV infection. METHODS Sera from 125 chronic HBV carriers were tested for the presence of HBSP antibodies by an indirect enzyme-linked immunosorbent assay test. The severity of liver damage was evaluated using the Knodell score. RESULTS Anti-HBSP antibody prevalence in HBV chronic carriers was 46%. We highlighted the concomitant expression of HBSP protein and anti-HBSP antibody. An association between anti-HBSP antibody detection and serum markers of HBV replication was demonstrated. With respect to HBV-related liver disease, an association was only observed with the severity of fibrosis. Furthermore, an elevation of secreted tumor necrosis factor alpha (TNFalpha), but not of soluble TNFalpha receptor 75, was observed in anti-HBSP-antibody-positive patients. Multivariate analysis showed that anti-HBSP antibody detection was independently associated with viral replication, severity of fibrosis and elevated TNFalpha secretion. CONCLUSIONS Our data suggest the hypothesis that HBSP might play a role in the natural history of HBV infection and may be involved in the pathogenesis and/or persistence of HBV infection.

Paracrine in vivo inhibitory effects of hepatitis B virus X protein (HBx) on liver cell proliferation: An alternative mechanism of HBx-related pathogenesis

The role of the hepatitis B virus X protein (HBx) in the pathogenesis of hepatitis B virus (HBV) infection remains unclear. HBx exhibits pleiotropic biological effects, whose in vivo relevance is a matter for debate. In the present report, we have used a combination of HBx-expressing transgenic mice and liver cell transplantation to investigate the in vivo impact of HBx expression on liver cell proliferation and viability in a regenerative context. We show that moderate HBx expression inhibits liver regeneration after partial hepatectomy in HBx-expressing transgenic mice. We also demonstrate that the transplantation of HBx-expressing liver cells, isolated from HBx transgenic mice, is sufficient to inhibit overall recipient liver regeneration after partial hepatectomy. Moreover, the injection of serum samples drawn from HBx-expressing transgenic mice mimicked the inhibitory effect of HBx on liver regeneration. Finally, the incubation of primary rat hepatocytes with the supernatant of HBx-expressing liver cells inhibits cellular DNA synthesis. Taken together, our results demonstrate a paracrine inhibitory effect of HBx on liver cell proliferation and lead us to propose HBV as one of the few viruses implicated in human cancer which act, at least in part, through paracrine biological pathways.

Role of uncoupling protein UCP2 in cell-mediated immunity: How macrophage-mediated insulitis is accelerated in a model of autoimmune diabetes

Infiltration of inflammatory cells into pancreatic islets of Langerhans and selective destruction of insulin-secreting β-cells are characteristics of type 1 diabetes. Uncoupling protein 2 (UCP2) is a mitochondrial protein expressed in immune cells. UCP2 controls macrophage activation by modulating the production of mitochondrial reactive oxygen species (ROS) and MAPK signaling. We investigated the role of UCP2 on immune cell activity in type 1 diabetes in Ucp2-deficient mice. Using the model of multiple low-dose streptozotocin (STZ)-induced diabetes, we found that autoimmune diabetes was strongly accelerated in Ucp2-KO mice, compared with Ucp2-WT mice with increased intraislet lymphocytic infiltration. Macrophages from STZ-treated Ucp2-KO mice had increased IL-1β and nitric oxide (NO) production, compared with WT macrophages. Moreover, more macrophages were recruited in islets of STZ-treated Ucp2-KO mice, compared with Ucp2-WT mice. This finding also was accompanied by increased NO/ROS-induced damage. Altogether, our data show that inflammation is stronger in Ucp2-KO mice and islets, leading to the exacerbated disease in these mice. Our results highlight the mitochondrial protein UCP2 as a new player in autoimmune diabetes.

Role of GM-CSF in tolerance induction by mobilized hematopoietic progenitors

Mechanisms of protection against autoimmune diseases by transplantation of autologous hematopoietic progenitors remain poorly defined. We recently demonstrated that, unlike medullary hematopoietic stem cells (HSCs), mobilized hematopoietic progenitors (HPCs) stimulate peripheral Foxp3(+) regulatory T cell (Treg)-expansion through cell-contact activation of Notch signaling and through as yet undetermined soluble factor(s), distinct from TGF-beta1. Herein we identified one such soluble factor as granulocyte macrophage-colony stimulating factor (GM-CSF), which is produced at higher levels by HPCs than HSCs and whose neutralization significantly reduces the growth-promoting effect of HPCs on Treg. Treg express a functional GM-CSF receptor alpha-chain CD116 and proliferate in response to this cytokine independently from IL2. GM-CSF-expanded Treg-like HPC-expanded Treg-display enhanced suppressive capacity relative to control Treg. Hence, mobilized progenitors stimulate Treg expansion both by cell-contact dependent mechanisms and by their production of GM-CSF.

Inflammatory cytokines and inhibitors in HIV infection : correlation between interleukin-1 receptor antagonist and weight loss

Objective:To determine serum levels of the interleukin-1 receptor antagonist (IL-1Ra), together with cytokines, other cytokine inhibitors and markers of immune activation in HIV-infected patients. Methods:Sixty-one HIV-patients were classified into Center for Disease Control and Prevention (CDC) groups A (n = 14), B (n = 14) and C (n = 33). Serum levels of IL-1Ra, IL-1β, IL-6, tumour necrosis factor (TNF)-α, TNF soluble receptors (TNF-sR) and IL-2sR were measured by enzyme-linked immunosorbent assay. CD4+ cell counts, p24 antigen, immunoglobulin (Ig) A, β2-microglobulin, triglycerides and neopterin were measured according to standard procedures. Weight variation was measured as the percentage of baseline weight lost or gained during the 3 months before sampling. Results:Serum levels of IL-1Ra were significantly elevated in HIV-infected patients, compared with control subjects (547 ± 104 and 133 ± 7 pg/ml), but did not vary significantly with the HIV disease stage, CD4+ cell count or p24 antigenaemia. IL-1Ra levels correlated with IL-1β(P < 0.005), IL-6 (P < 0.0001) and TNF-sR55 (P < 0.0001) levels, but not with those of TNF-α, TNF-sR75, IL-2sR, neopterin or IgA. IL-1Ra and IL-1Ra/IL-1β ratio were the only parameters significantly elevated (R = − 0.67, P < 0.0001) in the HIV-infected patients with marked weight loss (n = 12; mean of weight variation, −13.9 ± 2.1%) relative to the other patients, regardless of HIV disease stage and opportunistic infections. Conclusions:IL-1Ra levels are significantly elevated in HIV-infected patients, independently of immune deficiency. We propose that IL-1Ra accumulates in intense systemic inflammation, a state which does not seem to be reflected by the elevation of a single cytokine or the activation of a single cell system and which is correlated with marked weight loss.

Biphasic transforming growth factor-β production flanking the pro-inflammatory cytokine response in cerebral trauma

We determined the time-course of the production of transforming growth factor-β (TGF-β) after fluid-percussion injury using a bioassay. Biophasic production of TGF-β composed mainly of TGF-β2 was detected in the ipsilateral cortex, with a first peak 30 min and a second peak 48 h after the lesion, flanking the transient production of tumor necrosis factor-α and interleukin-6 occurring between 5 and 18 h after trauma. This temporal pattern suggested that TGF-β plays alternatively a pro- and anti-inflammatory role in the regulation of the brain cytokine network in response to injury, providing an endogenous mechanism for the control of the inflammatory reaction in traumatic brain injury.