Interleukin-10 Deficient Mice Research Articles

Interleukin‐6 Contributes to Endothelial Dysfunction in the Cerebral Circulation in Aging

The goal of this study was to examine the role of interleukin‐6 (IL‐6), a pro‐inflammatory cytokine, in the endothelial dysfunction associated with aging in the cerebral circulation. Vascular responses were examined in basilar arteries from young (6 mo) and old (24 mo of age) wild‐type (WT) and IL‐6‐deficient mice. Dilatation to acetylcholine (ACh), an endothelium‐dependent agonist, was similar (P>0.05) in basilar arteries from young WT and young IL‐6 deficient mice. For example, 100 μM ACh produced 65±3% and 71±4% dilatation in basilar arteries from young WT and young IL‐6 deficient mice, respectively. With age, responses to ACh were impaired by ~100% in old WT mice as compared to their young counterparts. We have shown previously that this impairment of endothelial function in the basilar artery with age is mediated by reactive oxygen species (ROS). In contrast, the response to 100 μM ACh was partially reduced in old IL‐6 deficient mice, however the degree of impairment was significantly less than that in old WT mice (e.g., 100 μM ACh produced 38±4% and 0±0% dilatation in old IL‐6 deficient and old WT mice, respectively). Responses to nitroprusside (an endothelium‐independent agonist) were not affected (P>0.05) by genotype or aging. These findings suggest that IL‐6, in part and/or in conjunction with ROS, contributes to the endothelial dysfunction observed with aging in the cerebral circulation.

Abstract B36: Induction of IL-6 by breast cancer chemotherapy mediates loss of fat-free lean body mass in tumor-free mice by decreasing systemic IGF-1

Abstract Aims: Cancer patients treated with cytotoxic chemotherapy often experience changes in body composition that occur independent of changes in food intake or physical activity. These changes may impact physical functioning and quality of life. Interleukin-6 (IL-6), an inflammatory cytokine that is up-regulated in cancer patients treated with cytotoxic chemotherapies, plays an important role in the regulation of body composition. The purpose of this study was to determine the role of IL-6 in the regulation of systemic insulin-like growth factor I (IGF-1) levels and treatment induced changes in body composition using a pre-clinical model. Methods: Changes in body composition and systemic IGF-1 levels were assessed in IL-6−/− mice and their wild type counterparts before and after 4 cycles of cytoxan-adriamycin-5-fluorouracil (CAF) a common adjuvant breast cancer chemotherapy regimen. Daily food intake and physical activity were monitored throughout treatment. Results: We found that CAF decreased systemic IGF-1 production in an IL-6-dependent manner. Similar to cancer patients, CAF treatment in WT mice led to a reduction in fat free LBM and bone mass but not fat mass (FM). These changes occurred independently of food intake and level of physical activity. In contrast, IL-6 deficient mice were protected from the treatment induced loss of fat free LBM but not bone mass. Conclusions: These preclinical findings implicate IL-6 mediated reduction in systemic IGF-1 as a possible mechanism underlying the loss of fat free LBM in cancer patients undergoing cytotoxic chemotherapy. Based upon these pre-clinical findings, examination of these relationships in the clinical setting is warranted. Citation Information: Clin Cancer Res 2010;16(7 Suppl):B36

Sex effects of Interleukin-6 deficiency on neuroinflammation in aged C57Bl/6 mice

High levels of Interleukin-6 (IL-6) are associated with an increased risk of dementia in the elderly and can increase neuroinflammation in mice. Dementia is more frequent in females, and IL-6 is regulated by estrogen, suggesting that elevated IL-6 levels may contribute to neuroinflammation and dementia particularly in women. Therefore we hypothesized that IL-6 deficient ( −/−) female mice would have lower aging-related neuroinflammation than wild type (WT). We quantified neuroinflammatory markers which are affected by aging, and regulated by both estrogen and IL-6; glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), interferon gamma (IFNγ), lipid peroxidation (MDA), and synaptic density (SNAP25) and in IL-6 −/− and WT C57Bl/6 mice. To determine age effects we used mid-age (18 months) and old-age (24 months) mice, and to determine region specific effects we used the hippocampus which is impaired in dementia and the cerebellum which is unimpaired in dementia. Unexpectedly, there were no effects of IL-6 deficiency on GFAP, MDA or SNAP25 levels in females, but IL-6 deficiency was associated with lower cerebellar MBP ( p < 0.05) levels. Interestingly, the old-aged IL-6 −/− males had higher GFAP and MDA levels ( p < 0.05) in both the hippocampus and cerebellum, in addition to a greater body weight than WT. We suggest that IL-6 is important for promoting myelin synthesis in aged females, and that drugs which inhibit the synthesis of IL-6 in males may inadvertently affect fatty acid metabolism and augment aging-related neuroinflammation.

IL-2 Regulates SEB Induced Toxic Shock Syndrome in BALB/c Mice

BackgroundToxic Shock Syndrome (TSS) is characterized by fever, rash, hypotension, constitutional symptoms, and multi-organ involvement and is caused by Staphylococcus aureus enterotoxins such as Staphylococcal Enterotoxin B (SEB). SEB binds to the MHC-IIα chain and is recognized by the TCRβ chain of the Vβ8 TCR+ T cells. The binding of SEB to Vβ chain results in rapid activation of T cells and production of inflammatory cytokines, such as Interleukin-2 (IL-2), Interferon-γ and Tumor Necrosis Factor-α which mediate TSS. Although IL2 was originally identified as the T cell growth factor and was proposed to contribute to T cell differentiation, its role in TSS remains unexplored.Methodology/Principal FindingsMice were injected with D-Gal (25 mg/mouse). One hour after D-Galactosamine (D-Gal) injection each mouse was injected with SEB (20 µg/mouse. Mice were then observed for 72 hrs and death was recorded at different times. We tested Interleukin-12, IFNγ, and IL-2 deficient mice (IL-2−/−), but only the IL-2 deficient mice were resistant to SEB induced toxic shock syndrome. More importantly reconstitution of IL-2 in IL-2 deficient mice restored the shock. Interestingly, SEB induced IL-2 production from T cells was dependent on p38MAPK activation in macrophages as inhibition of it in macrophages significantly inhibited IL-2 production from T cells.ConclusionThis study shows the importance of IL -2 in TSS which has not been previously explored and it also shows that regulating macrophages function can regulate T cells and TSS.

Bordetella evades the host immune system by inducing IL-10 through a type III effector, BopN

The inflammatory response is one of several host alert mechanisms that recruit neutrophils from the circulation to the area of infection. We demonstrate that Bordetella, a bacterial pathogen, exploits an antiinflammatory cytokine, interleukin-10 (IL-10), to evade the host immune system. We identified a Bordetella effector, BopN, that is translocated into the host cell via the type III secretion system, where it induces enhanced production of IL-10. Interestingly, the BopN effector translocates itself into the nucleus and is involved in the down-regulation of mitogen-activated protein kinases. Using pharmacological blockade, we demonstrated that BopN-induced IL-10 production is mediated, at least in part, by its ability to block the extracellular signal-regulated kinase pathway. We also showed that BopN blocks nuclear translocation of nuclear factor κB p65 (NF-κBp65) but, in contrast, promotes nuclear translocation of NF-κBp50. A BopN-deficient strain was unable to induce IL-10 production in mice, resulting in the elimination of bacteria via neutrophil infiltration into the pulmonary alveoli. Furthermore, IL-10–deficient mice effectively eliminated wild-type as well as BopN mutant bacteria. Thus, Bordetella exploits BopN as a stealth strategy to shut off the host inflammatory reaction. These results explain the ability of Bordetella species to avoid induction of the inflammatory response.

P-ANCAs in autoimmune liver disorders recognise human β-tubulin isotype 5 and cross-react with microbial protein FtsZ

ObjectiveAutoimmune hepatitis and primary sclerosing cholangitis are chronic inflammatory disorders of unknown aetiology, frequently associated with the presence of perinuclear antineutrophil cytoplasmic antibodies (p-ANCAs) directed against an unknown antigen of...

Endogenous Interleukin-10 Inhibits Angiotensin II–Induced Vascular Dysfunction

Angiotensin II (Ang II) produces inflammation and endothelial dysfunction in blood vessels. We tested the hypothesis that interleukin 10 (IL-10), an antiinflammatory cytokine, protects against Ang II-induced vascular dysfunction. Responses of carotid arteries from wild-type and IL-10-deficient mice (IL-10(-/-)) were examined in vitro after overnight incubation with vehicle or Ang II (1 nmol/L). In arteries from wild-type mice, acetylcholine (an endothelium-dependent agonist) produced relaxation that was not affected by Ang II. In contrast, relaxation to acetylcholine in arteries from IL-10(-/-) mice was reduced by >50% by Ang II (P<0.05) and this effect was prevented by a scavenger of superoxide. Vascular superoxide increased approximately 2-fold (P<0.05) after treatment with Ang II in IL-10(-/-) mice but not in wild-type. After systemic administration of Ang II (1.4 mg/kg per day for 10 days), Ang II produced modest impairment of endothelial function in wild-type mice but marked impairment in IL-10(-/-) mice (P<0.05) that was reversed by a superoxide scavenger. Increases in arterial pressure in response to Ang II were similar in wild-type and IL-10(-/-) mice. These findings provide the first evidence that endogenous IL-10 limits Ang II-mediated oxidative stress and vascular dysfunction both in vitro and in vivo suggesting that at least some of the protective effects of IL-10 may occur within the vessel wall.

Interleukin-2 deficiency-induced T cell autoimmunity in the mouse brain

Interleukin-2 (IL-2) has been implicated in the pathogenesis of neurodevelopmental and neurodegenerative disorders. Studies from our lab have shown that adult IL-2 knockout (KO) mice exhibit septohippocampal pathology and related behavioral deficits. Compared to IL-2 wild-type (WT) mice, IL-2 KO mice have a marked and selective loss of septal cholinergic neurons that occurs between the third postnatal week and adulthood. Given that the development of septal neurons is completed by embryonic day 17 and that IL-2 KO mice exhibit peripheral autoimmunity that develops progressively post-weaning, our data and others led us to postulate that the loss of septal neurons in adult IL-2 KO mice is due to selective autoimmune neurodegeneration that coincides with increasing levels of peripheral autoimmunity. Thus, the present study tested the hypotheses: (1) that T cells selectively target the septum, and; (2) that T lymphocyte infiltration to the septum would correlate with peripheral autoimmune disease. We quantified CD3+ T cells in the septum, hippocampus, and cerebellum of IL-2 KO and IL-2 WT mice at ages ranging from 2 to 14 weeks. T cells infiltrated the brains of IL-2 deficient mice, but were not selective for the septum. Brain T lymphocyte levels in IL-2 KO mice correlated positively with the degree of peripheral autoimmunity. We did not detect CD19+ B lymphocytes, IgG-positive lymphocytes or IgG deposition indicative of autoantibodies in the brains of IL-2 KO mice. Further study is needed to understand how IL-2 deficiency-induced autoimmune T lymphocytes interact with endogenous brain cells to alter function and promote disease.

Interleukin‐10 Protects Against Vascular Dysfunction with Aging

Aging produces vascular inflammation and dysfunction in blood vessels. We tested the hypothesis that interleukin‐10 (IL‐10), a potent anti‐inflammatory cytokine, protects against aging‐induced vascular dysfunction. Responses of carotid arteries from young (7‐8 mo) and old (19‐20 mo) wild‐type and IL‐10 deficient mice (IL‐10‐/‐) were examined in vitro. In arteries from wild‐type mice, acetylcholine (an endothelium‐dependent agonist) produced relaxation that was not altered at this age. In contrast, relaxation to acetylcholine in arteries from IL‐10 deficient mice was markedly impaired with age. For example, relaxation of the carotid artery to 10 μmol/L acetylcholine was 87±3 and 48±2% in old wild‐type versus old IL‐10 deficient mice, respectively (P&lt;0.01). Tempol (1 mM), a scavenger of superoxide, did not affect responses in young or old wild‐type or young IL‐10 deficient mice, but restored vasodilation to acetylcholine to normal in old IL‐10 deficient mice. Relaxation of the carotid artery to nitroprusside was not altered in any group. These findings provide the first evidence that age‐related and superoxide‐mediated endothelial dysfunction occurred much earlier and to a greater extent with IL‐10 deficiency. Our findings suggest a novel role for IL‐10 in oxidative stress and age‐related vascular dysfunction.

Partial Replacement of Dietary (n-6) Fatty Acids with Medium-Chain Triglycerides Decreases the Incidence of Spontaneous Colitis in Interleukin-10–Deficient Mice

Enteral nutrition has a primary therapeutic effect in active Crohn’s disease. It is unknown which nutrient(s) account for this action, but a role for both the amount and type of dietary fat has been postulated. Some clinical and experimental data suggest that medium-chain triglycerides (MCT) may reduce intestinal inflammation. We aimed to assess the effect of replacing part of the dietary fat with MCT on the incidence and severity of colitis in interleukin (IL)-10(−/−) mice under specific pathogen-free conditions. Twenty-four IL-10(−/−) 4-wk-old mice were randomized to receive a control diet based on sunflower oil [(n-6) fatty acids (FA)] and an experimental isocaloric, isonitrogenous diet with 50% sunflower and 50% coconut oil (MCT diet). When the mice were 12 wk old, they were killed and the colon was examined for the presence of colitis, lymphocyte subpopulations and apoptosis, ex vivo cytokine production in supernatant of colon explants, toll-like receptor (TLR)-2 and TLR-9 mRNA, and FA profile in colonic tissue homogenates. Colitis incidence was lower in the IL-10(−/−) mice fed the MCT diet (1/12) than in the mice fed the control diet (8/12; P = 0.03). The histological damage score was also lower in the former (P < 0.0005). Feeding the MCT diet resulted in fewer total and apoptotic intraepithelial CD3+ and lamina propria CD3+CD4+ lymphocytes, as well as downregulated production of IL-6 and interferon-γ, and reduced TLR-9 mRNA. We conclude that partial replacement of dietary (n-6) FA with MCT decreases the incidence of colitis in a model of spontaneous intestinal inflammation and provide experimental arguments for a possible primary therapeutic effect of MCT in human Crohn’s disease.

Serum-based diagnosis and mouse models for preeclampsia

The overarching goal of this study is to use serum as a blueprint to establish in vivo and in vitro diagnostic and treatment models for pregnancy disorders such as preeclampsia and intrauterine growth restriction (IUGR). When combined, preeclampsia and IUGR complicate 10–15% of all pregnancies worldwide and are a major cause of maternal, fetal and neonatal mortality and morbidity. Despite intense investigation, these complications have remained enigmatic and the mechanisms that contribute to their emergence are largely unknown. We have recently initiated serum-based studies to establish in vitro and in vivo predictive and mechanistic assays for IUGR/preeclampsia. Our data strongly suggest that serum from preeclampsia/IUGR patients contains an „activity“ that disrupts cross-talk between placental invading trophoblasts and endothelial cells as well as causes preeclampsia and IUGR like symptoms in pregnant mice. The latter phenotype is particularly apparent in interleukin-10 (IL-10) deficient mice. A major task has been to expand these studies using a larger sample of human samples to verify these novel preliminary results and to identify the dysregulated protein component(s) by state of the art proteomic techniques such as mass spectrometry based Surface Enhanced Laser Desorption and Ionization-Time of Flight (SELDI-TOF). Results will be described with a focus on identification and biochemical and physiological properties of a novel protein that is invariably deficient in preeclampsia serum. Supported by the NIH-NCRR grant P20RR018728 and the Rhode Island Research Alliance Collaborative Research Award and STIFT (Foundation for Technology, Innovation and Research in Thuringia, Germany).

Endogenous antigen presenting cell-derived IL-10 inhibits T lymphocyte responses to commensal enteric bacteria

Interleukin-10 deficient (IL-10−/−) mice develop chronic T cell-mediated colitis when colonized with normal commensal bacteria, but germ-free (GF) IL-10−/− mice remain disease-free. Antigen presenting cells (APC) secrete regulatory cytokines that help determine T lymphocyte activation or tolerance. CD4 + T cells from the mesenteric lymph nodes of inflamed IL-10−/− mice secrete more IFN-γ and IL-17 when cultured with cecal bacterial lysate-pulsed splenic APC from IL-10−/− mice than when cultured with normal control APC. GF IL-10−/− APC induce similar IFN-γ and IL-17 responses; therefore, the functional difference between normal and IL-10 deficient APC is inherent to the lack of IL-10 and not secondary to inflammation. Bacterial lysate-pulsed normal APC cultured with CD4 + cells from colitic IL-10−/− mice or with exogenous IFN-γ secrete higher amounts of IL-10 compared to the same APC cultured with naïve T cells. APC enriched for CD11c + cells are potent activators of IFN-γ and IL-17 production by CD4 + cells from IL-10−/− mice. These APC also produce IL-12/IL-23 p40 and IL-10. Recombinant IL-10 suppressed and anti-IL-10 receptor antibody increased IFN-γ, IL-17 and IL-12/IL-23 p40 production in bacterial lysate-pulsed APC and plus CD4 + T cell co-cultures. Taken together, our results show that endogenous IL-10 produced by APC inhibits responses to commensal bacteria and influences the ability of APC to stimulate IFN-γ-producing effector lymphocytes, which reciprocally, induce IL-10 production by APC. Cytokines produced by APC are an important determinant of pathogenic versus protective mucosal immune responses to colonic bacterial stimulation.

Reduced lymphocyte infiltration during cytomegalovirus brain infection of interleukin-10–deficient mice

Interleukin (IL)-10 deficiency results in highly elevated levels of interferon (IFN)-gamma, as well as the IFN-gamma-inducible chemokines CXCL9 and CXCL10 within murine cytomegalovirus (MCMV)-infected brains. To test the hypothesis that these elevated chemokine levels would result in enhanced brain infiltration, we compared immune cell infiltration in response to MCMV brain infection between wild-type and IL-10 knockout (KO) mice. Longitudinal analysis following adoptive transfer of cells from beta-actin-luciferase transgenic wild-type mice showed maximal brain infiltration by peripheral immune cells occurred at 5 days post infection. Although the overall percentage of CD45(hi) cells infiltrating the brain was not altered by IL-10 deficiency, paradoxically, despite elevated chemokine levels, reduced T lymphocyte (CD8+) and natural killer (NK) (CD49b+) cell infiltration into the brain was observed in IL-10-deficient animals. This decreased lymphocyte infiltration was associated with elevated levels of the lymph node homing receptor L-selectin/CD62L on CD8+ T cells. Lymph node cells obtained from MCMV-infected mice deficient in IL-10 also displayed reduced migration towards CXCL10 when compared to wild-type animals. Taken together, these data show that despite elevated chemokine levels, absence of IL-10 results in reduced lymphocyte infiltration into MCMV-infected brains.

The surface protein TIGIT suppresses T cell activation by promoting the generation of mature immunoregulatory dendritic cells

Here we have identified a surface protein, TIGIT, containing an immunoglobulin variable domain, a transmembrane domain and an immunoreceptor tyrosine-based inhibitory motif that was expressed on regulatory, memory and activated T cells. Poliovirus receptor, which is expressed on dendritic cells, bound TIGIT with high affinity. A TIGIT-Fc fusion protein inhibited T cell activation in vitro, and this was dependent on the presence of dendritic cells. The binding of poliovirus receptor to TIGIT on human dendritic cells enhanced the production of interleukin 10 and diminished the production of interleukin 12p40. Knockdown of TIGIT with small interfering RNA in human memory T cells did not affect T cell responses. TIGIT-Fc inhibited delayed-type hypersensitivity reactions in wild-type but not interleukin 10-deficient mice. Our data suggest that TIGIT exerts immunosuppressive effects by binding to poliovirus receptor and modulating cytokine production by dendritic cells.

Therapeutic effects of triptolide on interleukin-10 gene-deficient mice with colitis

BackgroundTriptolide, the principal active ingredient in the extract of Chinese herb Tripterygium wilfordii Hook , has both anti-inflammatory and immunomodulatory activities. However, the potential therapeutic role of triptolide in IBD was still unknown. Interleukin-10 deficient mice, a well characterized experimental model of inflammatory bowel disease, spontaneously developed a Th1 T cell-mediated colitis with many similarities to Crohn's disease. This study was designed to investigate the therapeutic effect of triptolide on the chronic colitis in IL-10−/− mice. MethodsTriptolide was intraperitoneally administrated every another day for 8 weeks to IL-10−/− mice. The gross and histological appearances of the colon, the level of inflammatory mediators and transcription factor activation in the colon were evaluated and compared with the control group. ResultsThe 8-week administration of triptolide resulted in a significant decrease in the severity of colitis, together with lower production of TNF-α ,IFN-γ and IL-4 in colon. The level of serum amyloid A was decreased in triptolide-treated mice. Gene expressions of IL-12 and IL-23 in colon were also downregulated after treatment. Furthermore, administration of triptolide markedly reduced NF-кB activation in colon mucosa of IL-10−/− mice. ConclusionsThe efficacy of tritpolide treatment for the reduction of intestinal inflammation in IL-10−/− mice is a result of both anti-inflammatory and immunosuppressive activity. Triptolide holds significant potential for clinical applications for CD treatment.

The suppressive effect of triptolide on chronic colitis and TNF-α/TNFR2 signal pathway in interleukin-10 deficient mice

Recent studies have suggested a critical role of TNFR2 signaling associated with NF-κB activation in the pathogenesis of Crohn's disease. Triptolide, an extract from Tripterygium wilfordii Hook, has both anti-immune and anti-inflammatory effects. In this study, we evaluated its possible therapeutic effects on colitis in interleukin-10 deficient mice, a murine model of Crohn's disease. Triptolide was administered to IL-10 −/− mice intraperitoneally every other day for 8 weeks. The severity of colitis in IL-10 −/− mice was obviously reduced after triptolide treatment, with a reduction in the numbers of CD4+ T cells and macrophages in lamina propria. Triptolide also significantly decreased the production of TNF-α and IFN-γ in colon. Furthermore, triptolide suppressed TNFR2 expression and NF-κB activation in colon of IL-10 −/− mice. These data suggested that triptolide could ameliorate Th1-mediated chronic colitis and disordered immune state in IL-10 −/− mice. A possible mechanism could be inhibiting TNF-α/TNFR2 signal pathway.

Increased susceptibility to systemic candidiasis in interleukin-6 deficient mice 1

Interleukin-6 (IL-6) is a multifunctional cytokine that regulates multiple aspects of the innate immune response. It has been recently shown that endogenous IL-6 is crucial for an efficient defence against severe infections with Gram-negative and Gram-positive bacteria. The aim of the present study was to investigate the role of endogenous IL-6 in the defence against infection with the yeast Candida albicans. During experimental candidemia, IL-6 deficient mice (IL-6−/−) had a decreased survival and an increased fungal load in their organs when compared with IL-6+/+ controls, despite increased plasma concentrations of tumour necrosis factor-α (TNF), interleukin-1α (IL-1α) and IL-1β. IL-6−/− mice were not able to mount an efficient neutrophil response during the infection. When mice were rendered neutropenic by cyclophosphamide, neutropenic IL-6−/− mice were equally susceptible to C. albicans when compared to neutropenic IL-6+/+mice, implying that neutrophils mediate the beneficial effect of endogenous IL-6. In conclusion, IL-6−/− mice are more susceptible to disseminated candidiasis, and the effect of IL-6 is most likely mediated by neutrophils.

Classical Complement Pathway in Experimental Autoimmune Myasthenia Gravis Pathogenesis

Mice deficient for complement factors C3, C4, or C5 are resistant to experimental autoimmune myasthenia gravis (EAMG). Acetylcholine receptor (AChR) immune lymph node cells (LNC) of C3 deficient mice produce less interleukin 6 (IL-6), and EAMG-resistant IL-6 deficient mice have less serum C3. Increased serum C1q-circulating immune complex (CIC) levels correlated with EAMG disease severity in RIIIS/J mice. The CIC promotes EAMG severity by stimulating the production of LNC IL-6, serum C1q, and C3 via FCgammaR interaction. Therefore, EAMG/MG could be treated by blocking the activation of classical complement pathway (CCP) and/or IL-6. Anti-C1q antibody administration before and following AChR immunization suppressed EAMG by reducing LNC IL-6 production and neuromuscular junction deposits of IgG, C3, and C5b-C9 complexes. Treatment with low dose (10 microg) of anti-C1q antibody twice a week for 4 weeks in mice with ongoing clinical EAMG reduced the clinical severity of disease and LNC IL-6 production. Therefore, inhibitors of CCP factors C1q, C2, or C4 could treat MG and would preserve the alternate complement pathway activation. Our goal is to tailor MG therapy using anti-C2/C4 reagents in combination, with or without anti-cytokine (e.g., anti-IL-6) reagents.

Reduced liver injury in the interleukin‐6 knockout mice by chronic carbon tetrachloride administration

Interleukin-6 has been involved in restoration of liver function after partial hepatectomy and toxic liver injury. However, normal liver regeneration in interleukin-6 knockout mice has also been reported. The aim of this work was to investigate the effect of interleukin-6 deficiency on liver injury and its regeneration in a model of long term carbon tetrachloride (CCl4) administration. Serum and whole livers from wild type and interleukin-6 knockout mice treated with carbon tetrachloride (0.25 mL kg(-1)) twice a week were obtained after 4, 6 and 8 weeks (n = 4-6). Sections were assessed for liver regeneration, liver injury and hepatocyte apoptosis whereas sera were assayed for aminotransferase levels. Nuclear extracts and total liver lysates were assayed for transcription factor activation and apoptosis related proteins, respectively. When compared to wild type, interleukin-6 knockout mice showed reduced liver damage scores, lower aminotransferase levels and diminished apoptosis, as well as reduced nuclear factor kappa B activation. Although the level of active protein was lower, activation of signal transducer and activator of transcription 3 still takes place in knockout mice. Furthermore, liver regeneration measured by bromodeoxyuridine incorporation showed no differences between wild type and knockout animals after 6 and 8 weeks of treatment. Compared to the wild type mice liver regeneration after chronic treatment with carbon tetrachloride proceeds at a slower rate in interleukin-6 deficient mice. However, this low recovery rate is accompanied by a reduction not only in hepatocyte apoptosis, but also in activation of nuclear factor kappa B and liver injury.

Anti-inflammatory properties of lactic acid bacteria producing superoxide dismutase

to the editor: We have read with interest the recent paper by Carroll et al. ([1][1]) showing that a treatment with Lactobacillus gasseri engineered to produce superoxide dismutase (SOD) reduces the spontaneous colitis observed in interleukin 10 (IL-10)-deficient mice. Four months before the authors