151
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Montoye T, Piessevaux J, Lavens D, Wauman J, Catteeuw D, Vandekerckhove J, Lemmens I, Tavernier J. Analysis of leptin signalling in hematopoietic cells using an adapted MAPPIT strategy. FEBS Lett 2006; 580:3301-7. [PMID: 16698021 DOI: 10.1016/j.febslet.2006.04.094] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 04/10/2006] [Accepted: 04/19/2006] [Indexed: 11/23/2022]
Abstract
The adipocyte-secreted hormone leptin participates in the regulation of hematopoiesis and enhances proliferation of hematopoietic cells. We used an adaptation of the MAPPIT mammalian two-hybrid method to study leptin signalling in a hematopoietic setting. We confirmed the known interactions of suppressor of cytokine signalling 3 (SOCS3) and STAT5 with the Y985 and Y1077 motifs of the leptin receptor, respectively. We also provide evidence for novel interactions at the Y1077 motif, including phospholipase C gamma and several members of the SOCS protein family, further underscoring the important role of the Y1077 motif in leptin signalling.
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Affiliation(s)
- T Montoye
- Flanders Interuniversity Institute for Biotechnology, Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Ghent University, A. Baertsoenkaai 3, B-9000 Ghent, Belgium
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152
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Morris AM, Sennello JA, Fayad RA, Eckel RH, Dinarello CA, Fantuzzi G. T cell-mediated hepatic inflammation modulates adiponectin levels in mice: role of tumor necrosis factor alpha. Metabolism 2006; 55:555-9. [PMID: 16546488 DOI: 10.1016/j.metabol.2005.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Accepted: 11/02/2005] [Indexed: 12/15/2022]
Abstract
Experimental T cell-mediated hepatitis induced by concanavalin A (ConA) results in the initiation of an inflammatory response and the production of cytokines. Adiponectin is an adipocytokine produced by adipose tissue that is involved in the reciprocal regulation of other cytokines, including tumor necrosis factor alpha (TNF-alpha). Concanavalin A administration to C57BL/6J mice reduced circulating levels of adiponectin, whereas leptin was markedly increased. Adiponectin messenger RNA expression in adipose tissue was also decreased; however, the expression of both the adiponectin receptors remained unchanged. Neutralization of TNF-alpha reduced ConA-induced liver damage, and this was associated with restored circulating levels of adiponectin. These findings indicate that inflammation-induced TNF-alpha is a critical mediator of adipose-tissue-derived adiponectin in vivo.
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Affiliation(s)
- Alison M Morris
- Division of Endocrinology, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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153
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Plaisancie P, Ducroc R, El Homsi M, Tsocas A, Guilmeau S, Zoghbi S, Thibaudeau O, Bado A. Luminal leptin activates mucin-secreting goblet cells in the large bowel. Am J Physiol Gastrointest Liver Physiol 2006; 290:G805-12. [PMID: 16455789 DOI: 10.1152/ajpgi.00433.2005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Leptin has been suggested to be involved in tissue injury and/or mucosal defence mechanisms. Here, we studied the effects of leptin on colonic mucus secretion and rat mucin 2 (rMuc2) expression. Wistar rats and ob/ob mice were used. Secretion of mucus was followed in vivo in the rat perfused colon model. Mucus secretion was quantified by ELISA, and rMuc2 mRNA levels were quantified by real-time RT PCR. The effects of leptin alone or in association with protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) inhibitors on mucin secreted by human mucus-secreting HT29-MTX cells were determined. Leptin was detected in the rat colonic lumen at substantial levels. Luminal perfusion of leptin stimulates mucus-secreting goblet cells in a dose-dependent manner in vivo in the rat. Leptin (10 nmol/l) increased mucus secretion by a factor of 3.5 and doubled rMuc2 mRNA levels in the colonic mucosa. There was no damage to mucosa 24 h after leptin, but the number of stained mucus cells significantly increased. Leptin-deficient ob/ob mice have abnormally dense mucus-filled goblet cells. In human colonic goblet-like HT29-MTX cells expressing leptin receptors, leptin increased mucin secretion by activating PKC- and PI3K-dependent pathways. This is the first demonstration that leptin, acting from the luminal side, controls the function of mucus-secreting goblet cells. Because the gel layer formed by mucus at the surface of the intestinal epithelium has a barrier function, our data may be relevant physiologically in defence mechanisms of the gastrointestinal tract.
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154
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Nakatsuji T. Rat thymectomy effects on leptin receptor and T-bet: erythroid hyperplasia with maturation arrest and suppressed T-cell-mediated hepatotoxicity. ACTA ACUST UNITED AC 2006; 12:2-10. [PMID: 16513541 DOI: 10.1532/lh96.04062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Thymectomy is an inevitable therapy for thymoma. Therefore, determining hemato-immune changes post-thymectomy is important. Twenty-six normal LEW/Sea rats thymectomized (Tx) at the ages of 38 +/- 5 days were followed without any treatment for 4 months (experiments [Exp] A and B). In addition, 16 LEW/Sea rats Tx at the age of 42 days (Exp C and D) and 10 non-Tx control LEW/Sea rats (Exp E) were immunized with syngeneic male liver cells 2 to 3 times and followed 2.7 months after the first immunization. Flow cytometric (FCM) analysis of mesenteric lymph nodes (MLN) and peripheral blood (PB) showed as follows: among the 26 Tx rats (Exp A and B), MLN lymphocyte population at 4 months postthymectomy was characterized by decreased numbers of CD4+ cells (22%-36%) or alphabeta T-cell receptor (TCR)-positive cells (16%-54%) and increased numbers of interleukin 2 receptors (IL-2R) (>90%). In the 16 Tx-immunized rats (Exp C and D), both alphabeta TCR (MLN) and CD45R (PB) expression on lymphocytes was suppressed with rather high numbers of CD4. Bone marrow (BM) and PB hematological studies of the partially and totally Tx rats indicated the following: 8 BM of the 10 totally Tx males (Exp A) and the 7/10 male spleen showed erythroid hyperplasia with maturation arrest at the stage of basophilic erythroblasts and reticulocytopenia in the PB. One of the 10 males, which had both BM myeloid to erythroid (M/E) ratio of 4.3 and spleen myeopoiesis, was in a more advanced stage, a prestage of pure red cell aplasia (PRCA) with 22% of CD4+ MLN cells. Syngeneic liver cell immunization resulted in the Tx rats as follows: hepatotoxicity based on the immunization was weaker in the 16 Tx rats (Exp C and D) than in the 10 non-Tx rats (Exp E). Polymerase chain reaction (PCR) of PB and MLN showed compensatory activated leptin receptor (LR) and T-bet DNA in 19 Tx rats (Exp A and B) with abnormal FCM findings. The ineffective erythropoiesis at 4 months after thymectomy was explained by the erythroblast LR/erythropoietin receptor (EPOR) dysfunction. The low grade hepatotoxicity in the Tx rats (Exp C and D) was explained by the disturbed Th1 reactions (or the disturbed T-bet gene transcription) at postthymectomy.
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Affiliation(s)
- Tadako Nakatsuji
- Department of Transfusion, Hamamatsu University School of Medicine, Hamamatsu, Japan.
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155
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Gilliam LK, Jensen RA, Yang P, Weigle DS, Greenbaum CJ, Pihoker C. Evaluation of leptin levels in subjects at risk for type 1 diabetes. J Autoimmun 2006; 26:133-7. [PMID: 16380228 DOI: 10.1016/j.jaut.2005.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 10/27/2005] [Accepted: 11/15/2005] [Indexed: 11/21/2022]
Abstract
Type 1 diabetes (T1DM) is increasing in incidence worldwide, particularly in young children. Studies have suggested that weight gain in early childhood may play a role in determining disease risk, with increased risk in children who have gained more weight. We hypothesized that leptin may be involved by promoting a Th1-type immune response in individuals at risk for the development of T1DM. Insulin, GAD65, and IA-2 autoantibodies and leptin levels were measured in relatives of T1DM patients and in control subjects. After adjusting for HLA risk and age, autoantibody-positive relatives were compared with sex- and BMI-matched autoantibody-negative control subjects. BMI-matched individuals had similar leptin levels, and the leptin levels increased with increasing BMI Z-score, as expected. However, we did not demonstrate higher leptin levels in autoantibody-positive relatives, compared with autoantibody-negative control subjects. Thus, elevations in leptin levels do not appear to be a major determinant of whether an individual develops autoimmunity. If elevated BMI and associated elevations in leptin levels are risk factors for the initiation and/or progression of autoimmunity, they may act more as permissive factors in this process, in the setting of a certain degree of genetic predisposition.
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Affiliation(s)
- Lisa K Gilliam
- Department of Medicine, University of Washington, Seattle, WA 98195-7710, USA.
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156
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Dinarello CA. Interleukin 1 and interleukin 18 as mediators of inflammation and the aging process. Am J Clin Nutr 2006; 83:447S-455S. [PMID: 16470011 DOI: 10.1093/ajcn/83.2.447s] [Citation(s) in RCA: 274] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In this review, 2 cytokines are discussed with respect to the inflammatory processes that are fundamental to aging and mortality. Both interleukin (IL)-1 and IL-18 are members of the same structural family (IL-1 family, or IL-F); there are presently 9 members of this family, but with the exception of IL-1alpha, IL-1beta, and IL-18, the others are antagonists or remain without known function. IL-1alpha is an intracellular cytokine with properties of both a cytokine and a transcription factor. IL-1beta and IL-18 are closely related; both possess a similar three-dimensional structure, and their respective precursor forms are inactive until cleaved by the intracellular cysteine protease caspase-1. Patients with mutations in the NALP3 gene, which controls the activity of caspase-1, readily secrete more IL-1beta and IL-18 and suffer from systemic inflammatory diseases. Patients with defects in this gene have high circulating concentrations of IL-6, serum amyloid A, and C-reactive protein, each of which decrease rapidly upon blockade of the IL-1 receptor, which suggests that IL-1beta contributes to the elevation of these markers of the inflammatory mechanisms of aging. Animal studies support the concept that IL-1beta and IL-18 participate in the pathogenesis of atherosclerosis. For example, overexpression of the IL-18 binding protein, a naturally occurring, specific inhibitor of IL-18, prevents the spontaneous development of atherosclerosis in apolipoprotein E-deficient mice. From human and animal studies, one may conclude that IL-1beta and IL-18 participate in fundamental inflammatory processes that increase during the aging process.
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Affiliation(s)
- Charles A Dinarello
- Department of Medicine, Division of Infectious Diseases, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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157
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Elinav E, Pappo O, Sklair-Levy M, Margalit M, Shibolet O, Gomori M, Alper R, Thalenfeld B, Engelhardt D, Rabbani E, Ilan Y. Amelioration of non-alcoholic steatohepatitis and glucose intolerance in ob/ob mice by oral immune regulation towards liver-extracted proteins is associated with elevated intrahepatic NKT lymphocytes and serum IL-10 levels. J Pathol 2006; 208:74-81. [PMID: 16261527 DOI: 10.1002/path.1869] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Non-alcoholic steatohepatitis (NASH) is a common cause of cryptogenic cirrhosis in the Western world. In an animal model of NASH, leptin-deficient ob/ob mice present with alterations in number and function of hepatic NKT and peripheral CD4 lymphocytes. Oral immune regulation is a method to alter the immune response towards orally administered antigens. To determine the effect of oral immune regulation towards liver-extracted proteins on the metabolic disorders in ob/ob mice, ob/ob mice and their lean littermates were orally administered liver extracts from wild-type or ob/ob mice or bovine serum albumin for 1 month. The effect of treatment on hepatic fat content was measured by magnetic resonance imaging (MRI) and using a histological steatohepatitis grading scale. Glucose tolerance was measured by an oral glucose tolerance test (GTT). T lymphocyte subpopulations were assessed by flow cytometry analysis. Induction of immune regulation by oral presentation of liver-extracted proteins resulted in a significant 18% reduction of the hepatic fat content in ob/ob mice fed with either wild-type or ob/ob liver extracts for 1 month. The MRI signal intensity index in treated mice decreased to 0.48 and 0.51, respectively, compared with 0.62 in BSA-fed controls (p = 0.037 and p = 0.019, respectively), while the histological steatohepatitis score decreased in both treated groups to 2.0, compared with 2.4 in BSA-fed controls (p = 0.05). A significant improvement in GTT was noted in treated ob/ob mice. These changes were accompanied by a marked increase in the intrahepatic NKT lymphocyte population in mice fed with proteins extracted from both wild-type and ob/ob mice (46.96% and 56.72%, respectively, compared with 26.21% in BSA-fed controls; p < 0.05) and a significant elevation in serum IL-10 levels. Oral immune regulation towards liver extracted proteins in leptin-deficient mice resulted in a marked reduction in hepatic fat content and improved glucose tolerance. This effect was associated with a significant increase in the intrahepatic NKT lymphocyte population and serum IL-10 levels, suggesting a Th1 to Th2 immune shift. Immune regulation towards disease-associated antigens holds promise as a new mode of therapy for NASH.
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Affiliation(s)
- Eran Elinav
- Liver Unit, Department of Medicine, Hebrew University-Hadassah Medical Center, Jerusalem, Israel
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158
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López-Bermejo A, Bosch M, Recasens M, Biarnés J, Esteve E, Casamitjana R, Vendrell J, Ricart W, Fernández-Real JM. Potential role of interleukin-18 in liver disease associated with insulin resistance. ACTA ACUST UNITED AC 2006; 13:1925-31. [PMID: 16339124 DOI: 10.1038/oby.2005.237] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Interleukin (IL)-18 has been associated with obesity and insulin resistance, both risk factors for the development of liver disease, but the role of IL-18 in liver disease associated with insulin resistance is presently unknown. We hypothesized that circulating IL-18 would be related to serum concentrations of liver chemistry tests (LCTs) in apparently healthy subjects and wished to study whether this correlation was dependent on insulin sensitivity (S(I)). RESEARCH METHODS AND PROCEDURES One hundred six apparently healthy white men consecutively enrolled in a cross-sectional, population-based study dealing with S(I) in men were studied, and S(I) (minimal model analysis), LCTs (colorimetry), and IL-18 serum concentrations (immunoassay) were assessed. RESULTS Compared with subjects in the lowest quartile for serum IL-18, subjects in the highest quartile exhibited increased serum triglycerides and decreased S(I), in addition to higher serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) (all p < 0.05). The direct association between both ALT and AST and IL-18 was further confirmed by examining the distribution of serum IL-18 by quartiles of ALT and AST. Subjects in the highest quartile for serum ALT and AST had higher IL-18 concentrations compared with subjects in the lowest quartile for these LCTs (both p = 0.01). In multiple regression analysis, IL-18, but not S(I), was an independent predictor of serum concentrations of ALT and AST, explaining 7% and 4% of their variance, respectively. DISCUSSION In summary, IL-18 serum concentrations are associated in apparently healthy humans with plasma concentrations of various LCTs. IL-18 could contribute to the development of liver disease associated with insulin resistance.
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Affiliation(s)
- Abel López-Bermejo
- Unit of Diabetes, Endocrinology, and Nutrition, Dr. Josep Trueta Hospital, Av. Francia s/n, 17007 Girona, Spain.
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159
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Abstract
Leptin is produced primarily by adipocytes and functions in a feedback loop regulating body weight. Leptin deficiency results in severe obesity and a variety of endocrine abnormalities in animals and humans. Several studies indicated that leptin plays an important role in immune responses. It exerts protective anti-inflammatory effects in models of acute inflammation and during activation of innate immune responses. In contrast, leptin stimulates T lymphocyte responses, thus having rather a proinflammatory role in experimental models of autoimmune diseases. Clinical studies have so far yielded inconsistent results, suggesting a rather complex role for leptin in immune-mediated inflammatory conditions in humans.
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Affiliation(s)
- Eiva Bernotiene
- Department of Experimental Research, Institute of Experimental and Clinical Medicine, Vilnius University, Vilnius, Lithuania
| | - Gaby Palmer
- Division of Rheumatology, Department of Internal Medicine, University Hospital, Geneva, Switzerland
- Department of Pathology and Immunology, University of Geneva School of Medicine, Geneva, Switzerland
| | - Cem Gabay
- Division of Rheumatology, Department of Internal Medicine, University Hospital, Geneva, Switzerland
- Department of Pathology and Immunology, University of Geneva School of Medicine, Geneva, Switzerland
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160
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Ito Y, Abril ER, Bethea NW, McCuskey MK, McCuskey RS. Dietary Steatotic Liver Attenuates Acetaminophen Hepatotoxicity in Mice. Microcirculation 2006; 13:19-27. [PMID: 16393943 DOI: 10.1080/10739680500383423] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To determine whether hepatic steatosis is susceptible to acetaminophen (APAP) hepatotoxicity. METHODS Male C57Bl/6 mice were fed a "Western-style" diet (high fat and high carbohydrate) for 4 months to develop severe hepatic steatosis with mild increases in alanine aminotransferase (ALT) levels. These were compared to mice fed a standard chow diet. RESULTS Treatment with APAP (300 mg/kg, orally) to mice fed a regular chow increased ALT levels (519-fold) and caused hepatic centrilobular injury at 6 h. APAP increased hepatic cytochrome-P (CYP)-2E1 mRNA levels (17-fold). In vivo microscopic studies showed that APAP caused a 30% decrease in sinusoidal perfusion and the infiltration of red blood cells into the space of Disse. Electron microscopy demonstrated that numerous gaps were formed in sinusoidal endothelial cells. Mice fed the "Western-style" diet were protected from APAP hepatotoxicity as evidenced by 89% decrease in ALT levels and less centrilobular injury, which was associated with 42% decrease in CYP2E1 mRNA levels. The APAP-induced liver microcirculatory dysfunction was minimized in mice fed the "Western-style" diet. CONCLUSIONS These results suggest that hepatic steatosis elicited by the "Western-style" diet attenuated APAP-induced hepatotoxicity by inhibiting CYP2E1 induction and by minimizing sinusoidal endothelial cell injury, leading to protection of liver microcirculation.
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Affiliation(s)
- Yoshiya Ito
- Department of Cell Biology and Anatomy, College of Medicine, University of Arizona, Tucson, Arizona 85724-5044, USA
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161
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Dinarello CA. Inhibitors of histone deacetylases as anti-inflammatory drugs. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2006:45-60. [PMID: 16331856 DOI: 10.1007/3-540-37673-9_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This review addresses the issue of histone deacetylase (HDAC) inhibitors as developed for the treatment of cancer and for the investigation of the inhibition of inflammation. The review focuses on both in vitro and in vivo models of inflammation and autoimmunity. Of particular interest is the inhibition of pro-inflammatory cytokines. Although the reduction in cytokines appears paradoxical at first, upon examination, some genes that are anti-inflammatory are upregulated by inhibition of HDAC. Whether skin diseases will be affected by inhibitors of HDAC remains to be tested.
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Affiliation(s)
- C A Dinarello
- University of Colorado Health Sciences Center, Denver 80262, USA.
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162
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Fantuzzi G, Sennello JA, Batra A, Fedke I, Lehr HA, Zeitz M, Siegmund B. Defining the role of T cell-derived leptin in the modulation of hepatic or intestinal inflammation in mice. Clin Exp Immunol 2005; 142:31-8. [PMID: 16178853 PMCID: PMC1809499 DOI: 10.1111/j.1365-2249.2005.02898.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The role of leptin in the immune system has been well established. While adipocytes represent the major source, leptin production by lymphocytes, infiltrating at the site of inflammation, was recently demonstrated. However, the significance of this locally released leptin remains unresolved. In the present study, two models in which absence of leptin-signalling is associated with protection were employed: the model of ConA-induced hepatitis and the CD4(+)CD45Rb(high) transfer model of colitis. For the ConA model, scid mice were reconstituted with either WT or leptin-deficient (ob/ob) CD4(+) T cells. Eight weeks post transfer, ConA was injected and serum ALT, TNFalpha, leptin as well as liver mononuclear cell activation and histological signs of inflammation were evaluated. No difference between recipients of WT or ob/ob cells was observed for any of the parameters evaluated. In the second model, either WT or ob/ob CD4(+)CD45Rb(high) cells were transferred into scid mice. No histological differences were detected, although recipients of ob/ob cells showed higher weight loss compared to recipients of WT cells. Spontaneous production of IL-6 from colon cultures obtained from recipients of ob/ob cells was reduced compared to recipients of WT cells, whereas stimulation of lamina propria lymphocytes with leptin resulted in a higher IFNgamma release in recipients of ob/ob cells compared to recipients of WT cells. In conclusion, the present study provides evidence that T cell-derived leptin does not play a major role in the regulation of the inflammatory process, indicating that the adipose tissue is the critical player in the immune-modulating effects of leptin.
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Affiliation(s)
- G Fantuzzi
- Department of Medicine I, Charité, Campus Benjamin Franklin, Berlin, Germany
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163
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Robin MA, Demeilliers C, Sutton A, Paradis V, Maisonneuve C, Dubois S, Poirel O, Lettéron P, Pessayre D, Fromenty B. Alcohol increases tumor necrosis factor alpha and decreases nuclear factor-kappab to activate hepatic apoptosis in genetically obese mice. Hepatology 2005; 42:1280-90. [PMID: 16317704 DOI: 10.1002/hep.20949] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Both obesity and alcohol can cause oxidative stress, cytokine induction, and steatohepatitis. To determine the consequences of their combination, we compared the hepatic effects of moderate ethanol binges in lean and obese ob/ob mice. Mice received water or ethanol (2.5 g/kg) by gastric intubation daily for 4 days, and were killed 2 hours after the last administration. Some obese mice also received pentoxifylline, an inhibitor of tumor necrosis factor-alpha (TNF-alpha) production, before each ethanol administration. In lean mice, these moderate ethanol doses did not increase plasma TNF-alpha and hepatic caspase-3 activity, but triggered some apoptotic hepatocytes. Naive ob/ob mice had a few necrotic and apoptotic hepatocytes, but exhibited little oxidative stress, possibly because of adaptive increases in manganese superoxide dismutase, heat shock protein 70 (Hsp70), mitochondrial cytochrome c, and mitochondrial DNA. Alcohol administration to ob/ob mice did not increase oxidative stress despite increased CYP2E1, but increased plasma TNF-alpha, further increased Hsp70, and profoundly decreased p65 nuclear factor kappaB (NF-kappaB) protein and DNA-binding activity in nuclear extracts. Caspase-3 was activated, and more apoptotic hepatocytes were found in intoxicated obese mice than naive obese mice. In intoxicated obese mice, pentoxifylline fully prevented the increase in plasma TNF-alpha the decrease in nuclear NF-kappaB activity, and the increase in hepatic caspase-3, and it also decreased hepatic triglycerides. In conclusion, obese mice develop adaptations that may limit oxidative stress. Moderate ethanol intoxication does not increase oxidative stress in obese mice, but increases TNF-alpha and also decreases nuclear NF-kappaB activity, thus unleashing the apoptotic effects of TNF-alpha.
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Affiliation(s)
- Marie-Anne Robin
- INSERM Unité 481, Faculté de Médecine Xavier Bichat, Paris, France
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164
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Abstract
Adipose tissue is a highly active organ. In addition to storing calories as triglycerides, it also secretes a large variety of proteins, including cytokines, chemokines and hormone-like factors, such as leptin, adiponectin and resistin. Intriguingly, many, if not most, of these adipose-derived proteins have dual actions; cytokines have both immunomodulatory functions and act as systemic or auto-/paracrine regulators of metabolism, while proteins such as leptin and adiponectin are regulators of both metabolism and inflammation. The production of pro-atherogenic chemokines by adipose tissue is of particular interest since their local secretion, e.g. by perivascular adipose depots, may provide a novel mechanistic link between obesity and the associated vascular complications.
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Affiliation(s)
- Cristiana E Juge-Aubry
- Endocrine Unit, Department of Internal Medicine, University Hospital of Geneva, Switzerland
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165
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Aleffi S, Petrai I, Bertolani C, Parola M, Colombatto S, Novo E, Vizzutti F, Anania FA, Milani S, Rombouts K, Laffi G, Pinzani M, Marra F. Upregulation of proinflammatory and proangiogenic cytokines by leptin in human hepatic stellate cells. Hepatology 2005; 42:1339-48. [PMID: 16317688 DOI: 10.1002/hep.20965] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Leptin upregulates collagen expression in hepatic stellate cells (HSCs), but the possible modulation of other actions has not been elucidated. The aim of this study was to investigate the expression and function of leptin receptors (ObR) in human HSCs and the biological actions regulated by leptin. Exposure of HSCs to leptin resulted in upregulation of monocyte chemoattractant protein 1 (MCP-1) expression. Leptin also increased gene expression of the proangiogenic cytokines vascular endothelial growth factor (VEGF) and angiopoietin-1, and VEGF was also upregulated at the protein level. Activated HSCs express ObRb and possibly other ObR isoforms. Exposure to leptin increased the tyrosine kinase activity of ObR immunoprecipitates and resulted in activation of signal transducer and activator of transcription 3. Several signaling pathways were activated by leptin in HSCs, including extracellular-signal-regulated kinase, Akt, and nuclear factor kappaB, the latter being relevant for chemokine expression. Leptin also increased the abundance of hypoxia-inducible factor 1alpha, which regulates angiogenic gene expression, in an extracellular-signal-regulated kinase- and phoshatidylinositol 3-kinase-dependent fashion. In vivo, leptin administration induced higher MCP-1 expression and more severe inflammation in mice after acute liver injury. Conversely, in leptin-deficient mice, the increase in MCP-1 messenger RNA and mononuclear infiltration was less marked than in wild-type littermates. Finally, ObR expression colocalized with VEGF and alpha-smooth muscle actin after induction of fibrosis in rats. In conclusion, ObR activation in HSCs leads to increased expression of proinflammatory and proangiogenic cytokines, indicating a complex role for leptin in the regulation of the liver wound-healing response.
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Affiliation(s)
- Sara Aleffi
- Dipartimento di Medicina Interna, University of Florence, Italy
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166
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Margalit M, Abu Gazala S, Ghazala SA, Alper R, Elinav E, Klein A, Doviner V, Sherman Y, Thalenfeld B, Engelhardt D, Rabbani E, Ilan Y. Glucocerebroside treatment ameliorates ConA hepatitis by inhibition of NKT lymphocytes. Am J Physiol Gastrointest Liver Physiol 2005; 289:G917-25. [PMID: 15976388 DOI: 10.1152/ajpgi.00105.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Concanavalin A (ConA) induces natural killer T (NKT) cell-mediated liver damage. Glucocerebroside (GC) is a naturally occurring glycolipid. Our aims were to determine the effect of GC in a murine model of ConA-induced hepatitis. Mice in groups A and B were treated with GC 2 h before and 2 h following administration of ConA, respectively; group C mice were treated with ConA; group D mice was treated with GC; group E mice did not receive any treatment. Liver damage was evaluated by serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver histology. The immune effect of GC was determined by fluorescence-activated cell sorter analysis of intrahepatic and intrasplenic NKT lymphocytes, measurement of cytokine levels, and Western blot analysis for STAT 1, 4, 6, and NF-kappaB expression. The effect of GC on NKT cell proliferation was assessed in vitro. Serum AST and ALT levels were markedly reduced in GC-treated group A mice compared with nontreated group C animals, and histological damage was markedly attenuated in group A. The beneficial effect of GC was associated with a 20% decrease of intrahepatic NKT lymphocytes, significant lowering of serum IFN-gamma levels, and decreased STAT1 and STAT6 expression. In vitro administration of GC led to a 42% decrease of NKT cell proliferation in the presence of dendritic cells but not in their absence. Intraperitoneally administered radioactive GC was detected in the liver and bowel. Administration of GC led to amelioration of ConA hepatitis associated with an inhibitory effect on NKT lymphocytes. GC holds promise as a new immune-modulatory agent.
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Affiliation(s)
- Maya Margalit
- Liver Unit, Department of Medicine, Hadassah University Hospital, Jerusalem, Israel
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167
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Fayad R, Sennello JA, Kim SH, Pini M, Dinarello CA, Fantuzzi G. Induction of thymocyte apoptosis by systemic administration of concanavalin A in mice: role of TNF-alpha, IFN-gamma and glucocorticoids. Eur J Immunol 2005; 35:2304-12. [PMID: 16047339 DOI: 10.1002/eji.200526062] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Administration of concanavalin A (Con A) is a well-established model of acute immune-mediated hepatitis. Here, we demonstrate that intravenous injection of Con A in mice induces profound thymic atrophy. Compared to liver damage, the kinetics of Con A-induced thymic atrophy is slower and more prolonged; the nadir in thymocyte number is reached 4 days after Con A injection, whereas peak transaminase levels are observed at 12-24 h. Marked alterations in the ratio of CD4+ and CD8+cells in the thymus and spleen and significantly increased rates of thymocyte and splenocyte apoptosis are observed. Neutralization of the cytokines TNF-alpha or IFN-gamma, which protects mice from Con A-induced hepatitis, prevents thymic atrophy as well as alterations in CD4+ and CD8+ cell numbers and apoptosis rates. However, neither TNF-alpha nor IFN-gamma are detectable in thymocyte lysates after Con A injection, whereas both cytokines are present in liver, spleen and serum. Administration of the glucocorticoid receptor antagonist mifepristone does not prevent thymic atrophy, thus ruling out a possible contribution of endogenous glucocorticoids. Con A-induced thymic atrophy is accompanied by down-regulation of Bcl-2 expression in the thymus, which is prevented by neutralization of TNF-alpha or IFN-gamma. These data demonstrate that the thymus is a critical target organ of Con A-induced inflammation; the effects of Con A on the thymus are mediated by extrathymic production of TNF-alpha and IFN-gamma, but not by glucocorticoids.
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Affiliation(s)
- Raja Fayad
- Department of Human Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA
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168
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Erkasap N, Ikizler M, Shneyvays V, Zinman T, Mamedova LK, Uyar R, Shainberg A. Leptin protects the cardiac myocyte cultures from hypoxic damage. Life Sci 2005; 78:1098-102. [PMID: 16202428 DOI: 10.1016/j.lfs.2005.06.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2004] [Accepted: 06/15/2005] [Indexed: 01/24/2023]
Abstract
Leptin, a circulating hormone mainly produced by adipose tissue, regulates fatty acid metabolism and causes multiple systemic biological actions even the regulation of cardiovascular function. It is previously known that leptin is a hypoxia-inducible hormone, that hypoxic conditions increase the expression of this peptide in various tissues such as placenta, pancreas and also in the heart. Since leptin receptors are present in the heart, we hypothesized that whether leptin was a protector response for tissues especially for the heart against the deleterious effects of hypoxia. Cultured cardiomyocytes from newborn rats were initially treated with 3000 ng/ml leptin incubation for 1, 5 and 20 h separately, then subjected to 120 min of hypoxia. Hypoxic damage of myocytes was assayed using the measurements of both lactate dehydrogenase and creatine kinase releases into the medium and performing morphological observations (ultrastructural and immunocytochemical) of plates. The obtained results from leptin treated and non-treated control groups were compared to each other, and these data have demonstrated that 5 h of leptin treatment before hypoxia provides a significant protection for cardiomyocytes against hypoxia. Neither 1- nor 20-h leptin treated groups exhibited sufficient protection against hypoxia. In conclusion, leptin protects the cardiomyocyte cultures from hypoxia, but this effect is selective and evident only in the 5-h treated myocytes.
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Affiliation(s)
- Nilufer Erkasap
- Osmangazi University, School of Medicine, Physiology Department, Eskisehir, Turkey
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169
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Wieland CW, Florquin S, Chan ED, Leemans JC, Weijer S, Verbon A, Fantuzzi G, van der Poll T. Pulmonary Mycobacterium tuberculosis infection in leptin-deficient ob/ob mice. Int Immunol 2005; 17:1399-408. [PMID: 16141243 DOI: 10.1093/intimm/dxh317] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The development of active tuberculosis after infection with Mycobacterium tuberculosis is almost invariably caused by a persistent or transient state of relative immunodeficiency. Leptin, the product of the obese (ob) gene, is a pleiotropic protein produced mainly by adipocytes and is down-regulated during malnutrition and starvation, conditions closely connected with active tuberculosis. To investigate the role of leptin in tuberculosis, we intranasally infected wild-type (Wt) and leptin-deficient ob/ob mice with live virulent M. tuberculosis. Ob/ob mice displayed higher mycobacterial loads in the lungs after 5 and 10 weeks of infection, although the difference with Wt mice remained 1 log of M. tuberculosis colony forming unit. Nevertheless, ob/ob mice were less able to form well-shaped granuloma and lung lymphocyte numbers were reduced compared with Wt mice early during infection. In addition, ob/ob mice had a reduced capacity to produce the protective cytokine IFNgamma at the site of the infection early during infection and upon antigen-specific recall stimulation, and showed reduced delayed-type hypersensitivity reaction to intra-dermal tuberculin purified protein derivative. Leptin replacement restored the reduced IFNgamma response observed in ob/ob mice. Mortality did not differ between ob/ob and Wt mice. These data suggest that leptin plays a role in the early immune response to pulmonary tuberculosis.
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Affiliation(s)
- Catharina W Wieland
- Laboratory of Experimental Internal Medicine, and Department of Pathology, Academic Medical Center, University of Amsterdam, The Netherlands.
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170
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Abstract
BACKGROUND The purpose of this study was to determine the leptin levels in children with chronic hepatitis B virus (HBV) infection, and to evaluate the effect of serum leptin levels on the end of therapy response (ETR). It is known that leptin stimulates T-cell immunity and so T-cell mediated immune response is critical in the outcome of chronic HBV infection. METHODS Leptin levels in children with chronic HBV infection were investigated and its effects on the ETR in 24 children who were treated with interferon-alpha and lamivudine combination therapy were evaluated. RESULTS The mean leptin level of the patients was higher than that of healthy children (P = 0.034). Of the patients, seven (29.2%) had ETR. The mean hepatic activity index and portal inflammation score were higher, the HBV DNA was lower, and the leptin level was similar in children with ETR when compared to others (P = 0.017, P = 0.04, P = 0.007, P = 0.34, respectively). HBV DNA and the fibrosis score were positively correlated (P = 0.016). CONCLUSION Although the higher leptin value observed in children with ETR was not statistically significant, because of close interactions between leptin, cytokines and lymphocytes, it is thought that leptin should be investigated as a predictive factor of ETR in further studies.
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Affiliation(s)
- Mukadder Ayşe Selimoglu
- Department of Pediatric Gastroenterology, Hepatology, and Nutrition, Faculty of Medicine, Atatürk University, Erzurum, Turkey
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171
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Liu ZW, Zhang N, Han QY, Zeng JT, Chu YL, Qiu JM, Wang YW, Ma LT, Wang XQ. Correlation of serum leptin levels with anthropometric and metabolic parameters and biochemical liver function in Chinese patients with chronic hepatitis C virus infection. World J Gastroenterol 2005; 11:3357-62. [PMID: 15948239 PMCID: PMC4315988 DOI: 10.3748/wjg.v11.i22.3357] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine serum leptin levels and investigate their correlations with anthropometric and metabolic parameters and biochemical liver function in patients with chronic hepatitis C virus (HCV) infection and their potential clinical implications.
METHODS: Forty-two chronic HCV-infected patients without anti-viral treatment were enrolled in this study, 30 patients had chronic hepatitis C, 10 had cirrhosis, and 2 had hepatocellular carcinoma (HCC). Thirty age- and sex-matched healthy individuals served as controls. Serum leptin levels were determined by ELISA. The biochemical liver function and serum lipids were determined at the same time. The height and body weight of patients and controls were measured, and body mass index (BMI) and body fat were calculated simultaneously. The correlations of serum leptin levels with anthropometric and metabolic parameters and biochemical liver function were assessed statistically.
RESULTS: The mean of serum leptin levels in patients with chronic hepatitis C, HCV-associated cirrhosis, HCV-associated HCC and control groups was (6.13±3.94), (5.25±4.21), (4.17±0.28), and (3.59±3.44) ng/mL, respectively. The serum leptin level in patients with chronic hepatitis C was significantly higher than that in controls. The serum leptin levels between cirrhotic patients and controls and between male and female cirrhotic patients had no significant difference. Serum leptin levels were positively-correlated with body fat, BMI, and apolipoprotein B (Apo B) in patients with chronic HCV infection. The serum alanine aminotransferase (ALT) levels were closely-correlated with BMI in patients with chronic hepatitis C.
CONCLUSION: HCV infection interferes with fat and lipid metabolism in patients with chronic HCV infection and leptin may play a role in hepatosteatosis.
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Affiliation(s)
- Zheng-Wen Liu
- Department of Infectious Diseases, First Hospital, Xi'an Jiaotong University, Xi'an 710061, Shaanxi Province, China.
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172
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Sennello JA, Fayad R, Morris AM, Eckel RH, Asilmaz E, Montez J, Friedman JM, Dinarello CA, Fantuzzi G. Regulation of T cell-mediated hepatic inflammation by adiponectin and leptin. Endocrinology 2005; 146:2157-64. [PMID: 15677756 DOI: 10.1210/en.2004-1572] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Concanavalin A-induced hepatotoxicity was compared in lipodystrophic aP2-nSREBP-1c transgenic mice (LD mice) lacking adipose tissue, obese leptin-deficient ob/ob mice, and lean wild-type (WT) mice. Serum leptin and adiponectin were low in LD mice, whereas ob/ob mice had undetectable leptin, but high adiponectin. Protection from hepatotoxicity was observed in ob/ob, but not in LD mice, despite low cytokine levels and reduced T cell activation and hepatic natural killer T cells in both groups. Administration of adiponectin protected LD mice from hepatotoxicity without altering cytokine levels. In contrast, administration of leptin heightened disease susceptibility by restoring cytokine production. Neutralization of TNF alpha protected LD mice from liver damage. Increased in vivo susceptibility to the hepatotoxic effect of TNF alpha was observed in LD mice. In vitro, adiponectin protected primary hepatocytes from TNF alpha-induced death, whereas leptin had no protective effect. In conclusion, although leptin increases susceptibility to hepatotoxicity by regulating cytokine production and T cell activation, adiponectin protects hepatocytes from TNF alpha-induced death.
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Affiliation(s)
- Joseph A Sennello
- Division of Infectious Diseases, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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173
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174
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Abstract
Leptin is an adipokine which conveys information on energy availability. In humans, leptin influences energy homeostasis and regulates neuroendocrine function primarily in states of energy deficiency. As a cytokine, leptin also affects thymic homeostasis and, similar to other proinflammatory cytokines, leptin promotes Th1 cell differentiation and cytokine production. We review herein recent advances on the role of leptin in the pathophysiology of immune responses.
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Affiliation(s)
- Giuseppe Matarese
- Gruppo di ImmunoEndocrinologia, Istituto di Endocrinologia e Oncologia Sperimenttale, Consiglio Nazionale delle Ricerche, Naples, Italy
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175
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Groeben H, Meier S, Brown RH, O'Donnell CP, Mitzner W, Tankersley CG. The effect of leptin on the ventilatory responseto hyperoxia. Exp Lung Res 2005; 30:559-70. [PMID: 15371092 DOI: 10.1080/01902140490489144] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Leptin-deficient mice show a blunted response to hypercapnia explained by central nervous system effects. The impact of leptin on peripheral chemoreceptor function is unclear. Therefore, 9 mutant (ob/ob) and 9 wild-type (+/+) mice were exposed to room air or 100% oxygen and respiratory rate (RR) and tidal volume (Vt) were measured. Subsequently, ob/ob mice received either leptin or vehicle and measurements were repeated. Compared to baseline, for +/+ mice, RR decreased significantly by 9.4% +/- 3.0% (means +/- SD), whereas Vt remained unchanged. Transition from normoxia to hyperoxia did not change RR and Vt in untreated ob/ob mice, whereas after leptin treatment, RR and Vt decreased significantly. Leptin deficiency abolishes the response to hyperoxia, which is restored by leptin replacement. Thus, leptin seems to be influential for a competent peripheral chemoreceptor function.
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Affiliation(s)
- Harald Groeben
- Department of Anesthesiology and Critical Care Medicine, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
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176
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Szyper-Kravitz M, Zandman-Goddard G, Lahita RG, Shoenfeld Y. The Neuroendocrine–Immune Interactions in Systemic Lupus Erythematosus: A Basis for Understanding Disease Pathogenesis and Complexity. Rheum Dis Clin North Am 2005; 31:161-75, x. [PMID: 15639061 DOI: 10.1016/j.rdc.2004.10.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Much progress has been made in the understanding of the impact of the neuroendocrine immune interactions and the pathogenic role in systemic lupus erythematosus, clinically and at the molecular level. This article focuses on the intertwining networks that involve the hypothalamic-pituitary-adrenal axis, cytokines within the central nervous system, and the sympathetic system. Hormones (estrogen, prolactin, gonadotropin-releasing hormone, and leptin) play an important role as immunomodulatory agents.
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177
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Ribeiro R, Lopes C, Medeiros R. Leptin and prostate: implications for cancer prevention--overview of genetics and molecular interactions. Eur J Cancer Prev 2005; 13:359-68. [PMID: 15452447 DOI: 10.1097/00008469-200410000-00002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Leptin's relation with obesity has been clearly demonstrated while its role in oncobiology is still largely unknown. Epidemiological studies on serum leptin provide valuable though controversial data, while in vitro studies consistently show leptin's angiogenic and proliferative potential in cancer. Leptin's activity is mediated by tissue-specific receptors, differentially expressed in organs such as the prostate. The molecular cascades triggered by leptin result in prostatic cell proliferation and angiogenic activity, thus linking the hormone mainly to prostate cancer prognosis. This review also addresses leptin's metabolic interactions with cytokines, growth factors or hormones, establishing perceptive pathways leading to carcinogenesis or prostate cancer progression and metastasis. Better understanding of these mechanisms may help in the development of new and more effective treatments for prostate cancer. The consolidation of leptin molecular genetics profile in prostate cancer patients may help to create susceptibility groups in normal individuals, facilitating a preventive dietary intervention or strategies for chemoprevention. We hypothesize that the balance between androgen and leptin levels may facilitate the increase in the ratio of androgen-independent prostate cancer cells to androgen-dependent cells in the tumour.
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Affiliation(s)
- R Ribeiro
- Molecular Oncology Unit, Instituto Português de Oncologia, Edifício Laboratórios--PISO 4, R. Dr. Ant. Bernardino Almeida, 4200-072 Porto, Portugal
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Abstract
Obesity is suggested as a risk factor for asthma, but the mechanisms are unclear. The relationship between obesity and asthma has not been considered in children born with very low-birth weight (VLBW). We hypothesized that overweight was a contributing factor for asthma in VLBW children, and that leptin and leptin-associated cytokines might play roles in overweight-related asthma. Seventy-four VLBW and 64 normal birth weight (NBW) children participated in a 12-yr follow up study assessing asthma and allergy. Twenty-seven (12 VLBW) of the 138 children were overweight according to the proposed international definition. The diagnosis of current asthma was made by a pediatrician. Serum levels of leptin and interferon (IFN)-gamma were analyzed by enzyme-linked immunosorbent assay (ELISA). Leptin levels were considerably higher in the overweight than in the non-overweight children (median value: 18.1 vs. 2.8 ng/ml, p < 0.001). In the overweight children, current asthmatics had twice as high levels of leptin as children without current asthma (median value: 30.8 vs. 14.3 ng/ml, p = 0.14), but this was not the case in the non-overweight children. IFN-gamma was more often detected in the overweight than in the non-overweight children (61% vs. 12%, p < 0.001), and there was a positive correlation between the levels of leptin and the levels of IFN-gamma (Rho = 0.40, p < 0.001). In the VLBW group, the overweight children had a significantly increased risk for current asthma compared with the non-overweight children after adjustment for the neonatal risk factors [adjusted odds ratio (OR) 5.8, 95% confidence interval (CI): 1.2-27]. Thus, overweight was associated with asthma in the VLBW children. Our hypothesis remained that leptin might be involved in the pathogenesis of asthma in the overweight children, and IFN-gamma might be a pathway in the process of leptin-induced inflammation.
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Affiliation(s)
- Xiao-Mei Mai
- Department of Molecular and Clinical Medicine, Division of Pediatrics, Linköping University, Linköping, Sweden.
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179
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Tauchmanovà L, Matarese G, Carella C, De Rosa G, Serio B, Ricci P, Lombardi G, Rotoli B, Colao A, Selleri C. High Serum Leptin in Patients with Chronic Graft-Versus-Host Disease after Hematopoietic Stem Cell Transplantation. Transplantation 2004; 78:1376-83. [PMID: 15548978 DOI: 10.1097/01.tp.0000140485.20848.b7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Increased serum leptin has been described after various organ transplants, with a mechanism that is still unclear. METHODS We measured serum leptin in 60 patients before and after allogeneic (allo) or autologous (auto) stem cell transplant (SCT) and in 60 healthy controls, matched for age and body mass index (BMI). RESULTS Serum leptin was higher in patients after SCT than before and in controls. Leptin production was higher after allo- than after auto-SCT; the presence of chronic graft-versus-host disease (cGVHD) was associated with the highest values. The physiological correlation with BMI was lost in the allogeneic setting, indicating a strong influence of factors other than the nutritional status on circulating leptin. No relationship was found between serum leptin levels and time from transplant, age, cortisol, C-reactive protein, and T-lymphocyte CD4-to-CD8 ratio. Among the cytokines secreted by type-1/type-2 T-helper lymphocytes, only serum interferon-gamma significantly correlated with serum leptin levels. Anti-leptin blocking antibodies partially inhibited T-cell activation in mixed lymphocyte reaction, suggesting a link between leptin and T-lymphocyte activation in the allo-SCT setting. CONCLUSION Taken together, these findings suggest that increased serum leptin concentrations may contribute to T-cell activation during development of cGVHD.
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Affiliation(s)
- Libose Tauchmanovà
- Department of Molecular and Clinical Endocrinology and Oncology, Federico II University of Naples, Naples, Italy
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180
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Miyagi T, Takehara T, Tatsumi T, Suzuki T, Jinushi M, Kanazawa Y, Hiramatsu N, Kanto T, Tsuji S, Hori M, Hayashi N. Concanavalin a injection activates intrahepatic innate immune cells to provoke an antitumor effect in murine liver. Hepatology 2004; 40:1190-6. [PMID: 15486936 DOI: 10.1002/hep.20447] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Concanavalin A (ConA), directly injected into mice, induces T cell-mediated liver injury. However, it remains unclear whether ConA injection can activate innate immune cells, including natural killer (NK) cells and natural killer T (NKT) cells, both of which exist abundantly in the liver. Here we report that ConA injection stimulated interferon (IFN)-gamma production from liver NKT cells as early as 2 hours after injection and augmented YAC-1 cytotoxicity of liver NK cells. ConA-induced NK cell activation required other types of immune cells and critically depended on IFN-gamma. Because a nonhepatotoxic low dose of ConA was capable of fully activating both NKT cells and NK cells, we next addressed the possibility of ConA injection displaying an antitumor effect in the liver without liver injury. A nonhepatotoxic low-dose ConA injection augmented the cytotoxicity of liver NK cells against Colon-26 colon cancer cells and suppressed hepatic metastasis of Colon-26 cells in a NK cell- and IFN-gamma-dependent manner. In conclusion, a nonhepatotoxic low dose of ConA might serve as an immunomodulator that can preferentially activate the innate immune cells to induce an antitumor effect against metastatic liver tumor.
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Affiliation(s)
- Takuya Miyagi
- Department of Molecular Therapeutics, Osaka University Graduate School of Medicine, Osaka, Japan
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181
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Abstract
Much of the hepatology literature to date has focused on the adaptive, antigen-specific response mediated by classical T-cell populations in both the protection and pathogenesis of liver disease. However, the liver is selectively enriched for cells representative of innate immunity, including natural killer T (NKT) cells. In particular, certain CD1d-reactive T cells are present at much higher frequencies in the liver than in the peripheral blood. Although these cells have previously been defined mostly on the basis of phenotypic markers, recent emerging literature regarding NKT cell populations has revealed considerable functional complexity. This review summarizes the recent literature regarding NKT cells, which may have important roles in a variety of liver diseases. Although there is an abundance of literature on the phenotype, distribution, and function of these cells in mice, much less is known about them in human health or liver diseases.
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182
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Sachot C, Poole S, Luheshi GN. Circulating leptin mediates lipopolysaccharide-induced anorexia and fever in rats. J Physiol 2004; 561:263-72. [PMID: 15388782 PMCID: PMC1665347 DOI: 10.1113/jphysiol.2004.074351] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Anorexia and fever are important features of the host's response to inflammation that can be triggered by the bacterial endotoxin lipopolysaccharide (LPS) and the appetite suppressant leptin. Previous studies have demonstrated that LPS induces leptin synthesis and secretion in the periphery, and that the action of leptin on appetite suppression and fever are dependent on brain interleukin (IL)-1beta. However, the role of leptin as a neuroimmune mediator of LPS-induced inflammation has not been fully elucidated. To address this issue, we neutralized circulating leptin using a leptin antiserum (LAS) and determined how this neutralization affected LPS-induced anorexia, fever and hypothalamic IL-1beta. Adult male rats were separated into four treatment groups, namely LPS + normal sheep serum (NSS), LPS + LAS, saline + LAS and saline + NSS. Intraperitoneal injection of LPS (100 microg kg(-1)) induced a significant reduction in food intake and body weight, which were significantly reversed in the presence of LAS (1 ml kg(-1)), 8 and 24 h after treatment. In addition, LPS-induced fever was significantly attenuated by LAS over the duration of the fever response (8 h). Lipopolysaccharide induced an increase of circulating IL-6, another potential circulating pyrogen, which was not affected by neutralization of leptin at 2 h. Interleukin-1beta mRNA at 1 and 8 h, and IL-1 receptor antagonist (ra) at 2 h were significantly upregulated in the hypothalamus of LPS-treated animals. The induction of these cytokines was attenuated in the presence of LAS. These results are the first to demonstrate that leptin is a circulating mediator of LPS-induced anorexia and fever, probably through a hypothalamic IL-1beta-dependent mechanism.
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Affiliation(s)
- Christelle Sachot
- Douglas Hospital Research Center, McGill University, 6875 boulevard LaSalle, Verdun, Quebec H4H 1R3, Canada
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183
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Dixit VD, Schaffer EM, Pyle RS, Collins GD, Sakthivel SK, Palaniappan R, Lillard JW, Taub DD. Ghrelin inhibits leptin- and activation-induced proinflammatory cytokine expression by human monocytes and T cells. J Clin Invest 2004; 114:57-66. [PMID: 15232612 PMCID: PMC437970 DOI: 10.1172/jci21134] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Accepted: 04/27/2004] [Indexed: 12/17/2022] Open
Abstract
Ghrelin, a recently described endogenous ligand for the growth hormone secretagogue receptor (GHS-R), is produced by stomach cells and is a potent circulating orexigen, controlling energy expenditure, adiposity, and growth hormone secretion. However, the functional role of ghrelin in regulation of immune responses remains undefined. Here we report that GHS-R and ghrelin are expressed in human T lymphocytes and monocytes, where ghrelin acts via GHS-R to specifically inhibit the expression of proinflammatory anorectic cytokines such as IL-1beta, IL-6, and TNF-alpha. Ghrelin led to a dose-dependent inhibition of leptin-induced cytokine expression, while leptin upregulated GHS-R expression on human T lymphocytes. These data suggest the existence of a reciprocal regulatory network by which ghrelin and leptin control immune cell activation and inflammation. Moreover, ghrelin also exerts potent anti-inflammatory effects and attenuates endotoxin-induced anorexia in a murine endotoxemia model. We believe this to be the first report demonstrating that ghrelin functions as a key signal, coupling the metabolic axis to the immune system, and supporting the potential use of ghrelin and GHS-R agonists in the management of disease-associated cachexia.
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Affiliation(s)
- Vishwa Deep Dixit
- Laboratory of Immunology, National Institute on Aging, NIH, Baltimore, Maryland 21224, USA
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184
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Siegmund B, Sennello JA, Lehr HA, Batra A, Fedke I, Zeitz M, Fantuzzi G. Development of intestinal inflammation in double IL-10- and leptin-deficient mice. J Leukoc Biol 2004; 76:782-6. [PMID: 15240754 DOI: 10.1189/jlb.0404239] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Leptin-deficient (ob/ob) mice are resistant in different models of autoimmunity and inflammation, suggesting that leptin regulates immunity and inflammation. To investigate whether leptin deficiency modulates the spontaneous intestinal inflammation observed in interleukin (IL)-10-deficient mice, double IL-10- and leptin-deficient [IL-10 knockout (KO) ob/ob] mice were generated and compared with single IL-10 KO mice for colitis severity. Body weight in IL-10 KO ob/ob mice was significantly reduced compared with that of ob/ob mice. However, when compared with wild-type or IL-10 KO mice, IL-10 KO ob/ob mice were still markedly obese. IL-10 KO and IL-10 KO ob/ob mice developed colitis with a comparable time-course and severity in terms of macroscopic and histologic scores. Likewise, production of interferon-gamma, IL-6, and IL-13 from colon cultures and splenocytes did not differ among these two groups. Conversely, rates of apoptosis were higher in lamina propria lymphocytes obtained from the colon of IL-10 KO ob/ob compared with IL-10 KO mice. In conclusion, although leptin deficiency has been associated with resistance in models of autoimmunity and inflammation induced by exogenous stimuli, leptin appears not to play a significant role in the spontaneous colitis of IL-10 KO mice, although it modulates survival of intestinal lymphocytes.
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Affiliation(s)
- Britta Siegmund
- Charité Universitaetsmedizin Berlin, Campus Benjamin Franklin, Germany
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185
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Peelman F, Waelput W, Iserentant H, Lavens D, Eyckerman S, Zabeau L, Tavernier J. Leptin: linking adipocyte metabolism with cardiovascular and autoimmune diseases. Prog Lipid Res 2004; 43:283-301. [PMID: 15234549 DOI: 10.1016/j.plipres.2004.03.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leptin was originally discovered as an adipocyte-derived hormone involved in the central control of body weight and energy homeostasis. It is now clear that leptin is a pleiotropic cytokine, with activities on many peripheral cell types. These findings may help explain the surprising role of leptin in pathophysiological processes. Recent evidence suggests that leptin contributes to atherosclerosis and to the increased risk of cardiovascular disease in obese people. Leptin also appears to be involved in T-cell-dependent immunity and possibly in the development and maintenance of certain autoimmune diseases. Here, we review the role of leptin in cardiovascular and autoimmune diseases, and also briefly address the potential therapeutic use of leptin antagonists.
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Affiliation(s)
- F Peelman
- Flanders Interuniversity Institute for Biotechnology, VIB09, Department of Medical Protein Research, Faculty of Medicine and Health Sciences, Ghent University, A. Baertsoenkaai 3, B-9000 Ghent, Belgium
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186
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Siegmund B, Sennello JA, Jones-Carson J, Gamboni-Robertson F, Lehr HA, Batra A, Fedke I, Zeitz M, Fantuzzi G. Leptin receptor expression on T lymphocytes modulates chronic intestinal inflammation in mice. Gut 2004; 53:965-72. [PMID: 15194645 PMCID: PMC1774108 DOI: 10.1136/gut.2003.027136] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
BACKGROUND Leptin regulates appetite through the long isoform of its receptor in the hypothalamus. Although leptin regulates immune responses, it is still unknown whether a direct effect of leptin on lymphocytes is required. AIMS To clarify whether expression of leptin receptors on T lymphocytes modulates intestinal inflammation in mice. METHODS The model of colitis induced by transfer of CD4(+)CD45RB(high) (RB(high)) cells into scid mice was used. Wild-type (WT) or leptin receptor deficient (db/db) RB(high) cells were transferred into scid mice and development of colitis evaluated. RESULTS Leptin receptors were expressed on both RB(high) and RB(low) cells. Intestinal lymphocytes of mice with colitis expressed high leptin levels compared with healthy controls whereas the opposite was true for serum leptin levels. Transfer of RB(high) cells from db/db mice induced delayed disease compared with transfer of WT cells. A high rate of apoptosis in lamina propria lymphocytes and reduced cytokine production were observed early on in scid mice receiving db/db RB(high) cells. These effects were not due to the high levels of glucocorticoids present in db/db mice as administration of corticosterone to WT mice failed to reproduce this phenomenon. High expression of peroxisome proliferator activated receptor gamma was observed in the colon of recipients of db/db compared with WT cells. Freshly isolated db/db RB(high) cells produced low levels of interferon gamma. Despite delayed onset of colitis, as disease progressed differences between mice receiving WT or db/db cells were no longer apparent. CONCLUSIONS These results suggest that leptin affects the immune response, partly by acting on the long isoform of its receptor expressed on T lymphocytes.
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Affiliation(s)
- B Siegmund
- Charite Universitaetsmedizin Berlin, Campus Benjamin Franklin, Medizinische Klinik I, Hindenburgdamm 30, 12200 Berlin, Germany
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187
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Dixit VD, Schaffer EM, Pyle RS, Collins GD, Sakthivel SK, Palaniappan R, Lillard JW, Taub DD. Ghrelin inhibits leptin- and activation-induced proinflammatory cytokine expression by human monocytes and T cells. J Clin Invest 2004. [DOI: 10.1172/jci200421134] [Citation(s) in RCA: 587] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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188
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Abstract
Leptin has a the potent effect on T cell mediated intestinal autoimmunity and may have a role in the development of such diseases.
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Affiliation(s)
- G Matarese
- Gruppo di ImmunoEndocrinologia, Istituto di Endocrinologia ed Oncologia Sperimentale, Consiglio Nazionale delle Ricerche (IEOS-CNR), c/o Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Napoli, Italy
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189
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Abstract
Leptin is an adipocyte-derived hormone/cytokine that links nutritional status with neuroendocrine and immune functions. As a hormone, leptin regulates food intake and basal metabolism, and is sexually dimorphic - that is, its serum concentration is higher in females than in males with a similar body fat mass. As a cytokine, leptin can affect thymic homeostasis and the secretion of acute-phase reactants such as interleukin-1 and tumour-necrosis factor. Similar to other pro-inflammatory cytokines, leptin promotes T helper 1 (TH1)-cell differentiation and can modulate the onset and progression of autoimmune responses in several animal models of disease. Here, we review the advances and controversy for a role of leptin in the pathophysiology of immune responses.
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Affiliation(s)
- Antonio La Cava
- Autoimmunity and Tolerance Laboratory, Department of Medicine, University of California Los Angeles, 1000 Veteran Avenue 32-59, Los Angeles, California 90095-1670, USA.
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190
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Abstract
Interleukin (IL)-18 is a new member of the IL-1 family of proinflammatory cytokines. Based on preclinical studies in animals, IL-18 likely plays a role in rheumatoid arthritis, and strategies to block IL-18 activity are underway in clinical trials. In one of these trials,a naturally occurring IL-18 binding protein (IL-18 BP) binds IL-18 with a high affinity and reduces disease severity in models of inflammatory diseases. IL-18 BP is not the soluble receptor for IL-18 but rather a distinct molecule, which appears to be distantly related to the IL-1 receptor type II, both structurally and functionally, and hence represents part of the IL-1 family of receptors.
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Affiliation(s)
- Charles A Dinarello
- Division of Infectious Diseases, Department of Medicine, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, B168, Denver, CO 80262, USA
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191
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Delayed resolution of acute inflammation during zymosan-induced arthritis in leptin-deficient mice. Arthritis Res Ther 2004; 6:R256-63. [PMID: 15142272 PMCID: PMC416449 DOI: 10.1186/ar1174] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2003] [Revised: 03/03/2004] [Accepted: 03/15/2004] [Indexed: 11/17/2022] Open
Abstract
The severity of antigen-induced arthritis (AIA) is decreased in leptin-deficient ob/ob mice. However, joint inflammation in AIA depends on the immune response, which is impaired in ob/ob mice. In the present study we investigated the effects of leptin deficiency on zymosan-induced arthritis (ZIA), which is independent of adaptive immunity. Arthritis was induced by injection of zymosan into the knee joint. Joint swelling was similar after 6 and 24 hours in ob/ob and control mice. However, it remained elevated in ob/ob animals on day 3 whereas values normalized in controls. Histology revealed similar articular lesions in all animals on day 3, but on days 14 and 21 arthritis tended to be more severe in ob/ob mice. The acute phase response, reflected by circulating levels of IL-6 and serum amyloid A, was also more pronounced in ob/ob mice, although corticosterone was significantly elevated in these animals. Similar results were obtained in leptin receptor-deficient db/db mice. Thus, in contrast to AIA, ZIA is not impaired in leptin-deficient animals. On the contrary, resolution of acute inflammation appears to be delayed in the absence of leptin or leptin signalling, suggesting that chronic leptin deficiency interferes with adequate control of the inflammatory response in ZIA.
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192
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Zhan M, Zhao H, Yang R, Han ZC. Serum leptin levels in patients with idiopathic thrombocytopenic purpura. Eur J Haematol 2004; 72:348-52. [PMID: 15059070 DOI: 10.1111/j.1600-0609.2004.00231.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES The purpose of this study was to evaluate serum leptin levels in idiopathic thrombocytopenic purpura (ITP), in order to determine the influence of leptin on the pathogenesis of ITP. SUBJECTS AND METHODS Forty-six untreated patients with chronic ITP were compared with 40 healthy people of similar age, sex and body mass index (BMI). Serum leptin levels (ng/mL) were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS We found that the mean serum leptin levels in patients with ITP (22.11 +/- 15.84 ng/mL) were significantly (P < 0.001) higher than that in healthy control volunteers (5.44 +/- 4.84 ng/mL). Furthermore, serum leptin levels in patients with ITP were inversely related (r = -0.86, P < 0.001) to the platelet counts and positively related to the platelet-associated IgG (PAIgG) levels (r = 0.7, P < 0.001). The levels of PAIgG and platelet counts were significantly different between leptin-positive (level greater than mean +/- 2 SD control value) and leptin-negative patients. CONCLUSION These findings suggest that leptin might play an important role in the pathogenesis of ITP.
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Affiliation(s)
- Mei Zhan
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 288 Nanjing Road, Tianjin 30020, China
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193
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Abstract
Increasing experimental evidence indicates that several factors that influence metabolism also play a role in the regulation of immune responses. Dissection of the interface connecting the metabolic and immune systems has recently gained wide interest. Particular focus has been on certain cytokines [interleukin-1 (IL-1), IL-6, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma)], hormones (leptin and insulin), neuropeptides (corticotropin-releasing hormone and alpha-melanocyte-stimulating hormone), immune-related proteins (zinc-alpha2-glycoprotein and attractin and/or mahogany), transcription factors (peroxisome-proliferator-activated receptors) and glucose metabolism. A better knowledge of the intricate network of interactions among energy regulation, immune surveillance and vital organ functions could in the near future lead to valuable strategies for therapeutic intervention in several immune-mediated diseases.
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Affiliation(s)
- Giuseppe Matarese
- Institute of Endocrinology/Oncology Research, c/o Department of Biology and Molecular-Cellular Pathology, Federico II University of Naples, Via S. Pansini 5, 80131 Naples, Italy.
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194
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Dinarello CA, Novick D, Rubinstein M, Lonnemann G. Interleukin 18 and interleukin 18 binding protein: possible role in immunosuppression of chronic renal failure. Blood Purif 2004; 21:258-70. [PMID: 12784053 DOI: 10.1159/000070699] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although interleukin (IL)-18 is a member of the IL-1 family of ligands, IL-18 appears to have unique characteristics, particularly in the regulation of the T helper type 1 (Th1) response. Th1 responses are required for tumor surveillance, killing intracellular organisms, and to provide help for antibody production. In patients with chronic renal failure, the well-known immunosuppression contributes to a failure to respond to infectious challenges and vaccinations. The most salient biological property of IL-18, linking this cytokine to the Th1 response, is its ability to induce interferon gamma (IFN-gamma). In fact, IL-18 was originally identified as an IFN-gamma-inducing factor, and IFN-gamma production is the hallmark of the Th1 response. Dysregulation of IFN-gamma production resulting from reduced activity of IL-18 would explain one of the mechanisms of immunosuppression in patients with chronic renal failure. The activity of IL-18 can be regulated by the IL-18-binding protein (IL-18BP), a glycoprotein of 40,000 daltons, which is constitutively expressed and appears to be the natural inhibitor of IL-18 activity. Unlike soluble receptors for IL-18, IL-18BP does not have a transmembrane domain; IL-18BP is a secreted protein possessing a high-affinity binding and ability to neutralize IL-18. IL-18BP was discovered in human urine and is excreted in health following glomerular filtration. With decreasing renal function, the concentrations of IL-18BP in the circulation are elevated as compared with subjects with a normal renal function, and these elevated levels may result in a decreased IL-18 activity. Because of the importance of IL-18 and IFN-gamma in the Th1 response, the biology of IL-18 and IL-18BP is reviewed here in the context of the immunosuppression of chronic renal failure.
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Affiliation(s)
- Charles A Dinarello
- Department of Medicine, University of Colorado Health Sciences Center, Denver, Colo 80262, USA
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195
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Mühlen KA, Schümann J, Wittke F, Stenger S, Van Rooijen N, Van Kaer L, Tiegs G. NK cells, but not NKT cells, are involved in Pseudomonas aeruginosa exotoxin A-induced hepatotoxicity in mice. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2004; 172:3034-41. [PMID: 14978108 DOI: 10.4049/jimmunol.172.5.3034] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pseudomonas aeruginosa exotoxin A (PEA) causes T cell- and Kupffer cell (KC)-dependent liver injury in mice. TNF-alpha as well as IL-18 and perforin are important mediators of liver damage following PEA injection. In this study, we focus on the role of NK and NKT cells in PEA-induced liver toxicity. Depletion of both NK and NKT cells by injection of anti-NK1.1 Ab as well as depletion of NK cells alone by anti-asialo GM1 Ab protected mice from PEA-induced hepatotoxicity, whereas mice lacking only NKT cells were susceptible. Additionally, we observed infiltration of NK cells, T cells, and neutrophils into liver parenchyma after injection of PEA. The number of NKT cells, however, remained unchanged. The increase in intrahepatic NK cells depended on KCs and the TNF-alpha-dependent up-regulation of the adhesion molecule VCAM-1 in the liver, but not on NKT cells. PEA also augmented the cytotoxicity of hepatic NK cells against typical NK target cells (YAC-1 cells). This effect depended on KCs, but not on TNF-alpha or NKT cells. Furthermore, only weak expression of MHC class I was detected on hepatocytes, which was further down-regulated in PEA-treated mice. This could explain the susceptibility of hepatocytes to NK cell cytolytic activity in this model. Our results demonstrate that NK cells, activated and recruited independently of NKT cells, contribute to PEA-induced T cell-dependent liver injury in mice.
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Affiliation(s)
- Katrin A Mühlen
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nürnberg, Erlangen, Germany
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196
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Sánchez-Pozo C, Rodriguez-Baño J, Domínguez-Castellano A, Muniain MA, Goberna R, Sánchez-Margalet V. Leptin stimulates the oxidative burst in control monocytes but attenuates the oxidative burst in monocytes from HIV-infected patients. Clin Exp Immunol 2004; 134:464-9. [PMID: 14632752 PMCID: PMC1808878 DOI: 10.1111/j.1365-2249.2003.02321.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Leptin, the 16 kDa product of the ob gene, is a an adipocyte-secreted hormone that centrally regulates weight. However, the physiological role of leptin is not limited to the regulation of food intake and energy expenditure, and leptin has a variety of effects in peripheral tissues, such as a regulatory role modulating the immune system. Thus, leptin receptor is expressed in human peripheral blood mononuclear cells, mediating the leptin stimulation of proliferation and activation, the production of proinflammatory cytokines from cultured monocytes, and the prevention of apoptotic death in serum-deprived monocytes. Because leptin can stimulate monocytes and the production of reactive oxygen species (ROS) are the result of monocyte activation, we investigated the effect of leptin on ROS production by human monocytes in vitro. Oxidative burst was measured by oxidation of the redox-sensitive dye 2',7'-dichlorofluorescein diacetate, and analysed by flow cytometry. We have found that stimulation with leptin produces oxygen radical formation by monocytes. This effect is dependent on the dose and maximal response is achieved at 10 nM leptin. Because HIV infection induces the production of ROS, we next investigated the effect of leptin on ROS production in monocytes from HIV-positive (HIV+) subjects. We have also found that monocytes from HIV+ subjects spontaneously produced increased amounts of free radicals. In contrast, leptin stimulation of monocytes from these patients partially inhibited the production of ROS. This effect of leptin was also dependent on the dose and maximal effect was achieved at 10 nM. The effect of leptin stimulating the production of ROS is consistent with the proinflammatory role in the immune system. On the other hand, the inhibitory effect on monocytes from HIV+ subjects may be explained by the attenuation of the oxidative burst by a delayed activation of monocytes in a hyperinflammatory state.
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Affiliation(s)
- C Sánchez-Pozo
- Department of Clinical Biochemistry, Virgen Macarena University Hospital, Seville, Spain
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197
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Rüter J, Hoffmann T, Demuth HU, Moschansky P, Klapp BF, Hildebrandt M. Evidence for an interaction between leptin, T cell costimulatory antigens CD28, CTLA-4 and CD26 (dipeptidyl peptidase IV) in BCG-induced immune responses of leptin- and leptin receptor-deficient mice. Biol Chem 2004; 385:537-41. [PMID: 15255186 DOI: 10.1515/bc.2004.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We assessed changes of the enzyme dipeptidyl peptidase IV (DPP IV, CD26) in the context of leptin or leptin receptor deficiency. C57BL/6 mice, Leptin-deficient mice (ob/ob mice, B6.V-Lep<ob>) and Leptin-receptor-deficient mice (db/db mice, B6.Cg-m+/+Lepr) were infected with B. Calmette-Guerin (BCG) and sacrificed three days later. DPP IV activity in serum was higher in ob/ob mice and in db/db mice than in wild-type mice. The expression of DPP IV/CD26 on splenocytes was higher in ob/ob mice than in wild-type animals, and lower in db/db mice, and decreased upon stimulation with BCG in ob/ob mice only. Several T cell antigens including CTLA-4 were expressed aberrantly in ob/ob and in db/db mice. Our observations provide evidence for a relationship between DPP IV and leptin.
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MESH Headings
- Animals
- Antigens, CD
- Antigens, Differentiation/genetics
- Antigens, Differentiation/immunology
- Antigens, Differentiation/metabolism
- BCG Vaccine/immunology
- CD28 Antigens/genetics
- CD28 Antigens/immunology
- CD28 Antigens/metabolism
- CTLA-4 Antigen
- Dipeptidyl Peptidase 4/genetics
- Dipeptidyl Peptidase 4/immunology
- Dipeptidyl Peptidase 4/metabolism
- Female
- Gene Expression Regulation, Enzymologic
- Leptin/genetics
- Leptin/immunology
- Leptin/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Mycobacterium bovis/immunology
- Mycobacterium bovis/metabolism
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/metabolism
- Receptors, Leptin
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Affiliation(s)
- Jens Rüter
- Department of Internal Medicine, Division of Psychosomatic Medicine and Psychotherapy, Charité University Hospital, Schumannstrasse 20/21, D-10117 Berlin, Germany
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198
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Sempere T, Urbina M, Lima L. 5-HT1A and beta-adrenergic receptors regulate proliferation of rat blood lymphocytes. Neuroimmunomodulation 2004; 11:307-15. [PMID: 15316241 DOI: 10.1159/000079411] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Accepted: 11/03/2003] [Indexed: 11/19/2022] Open
Abstract
Lymphocytes possess serotonin 5-HT(1A) and beta-adrenergic receptors, which have been related to cell proliferation. In the present report, lymphocytes of rat blood were isolated by Ficoll-Hypaque gradients and differential adhesion to plastic. They were cultured in RPMI medium for 72 h in the presence of the mitogens lipopolysaccharide concanavalin A and anti-CD3 antibody. The latter two stimulated the proliferation of lymphocytes, but not the first. Serotonin (0.1-100 microM) was added alone or in the presence of suboptimal concentrations of concanavalin A (2 microg/ml) or anti-CD3 antibody (0.4 microg/ml). The 5-HT(1A) receptor agonists, 8-hydroxy-2-(di-n-propylamino)tetralin and buspirone (0.1-100 microM) were also tested in the cultures. Serotonin, 8-hydroxy-2-(di-n-propylamino)tetralin and buspirone neither had any effect by themselves, nor modified the proliferation induced by the mitogens. Noradrenaline (25-1,000 microM) and the beta-adrenergic receptor agonist, isoproterenol (5-100 microM), produced a reduction of the activation induced by concanavalin A or anti-CD3 antibody in a dose-dependent manner. Increasing serotonin concentrations reduced the inhibitory effect of noradrenaline (300 microM). Variable concentrations of 8-hydroxy-2-(di-n-propylamino)tetralin or buspirone also reduced the inhibition produced by isoproterenol (100 microM). The antagonist of 5-HT(1A) receptors, WAY-100,478 (0.1-100 microM), inhibited concanavalin A- or anti-CD3 antibody-induced proliferation. Serotonin (0.1-100 microM) impaired the inhibitory effect of the 5-HT(1A) antagonist (10 microM). The inhibitor of tryptophan hydroxylase, p-chlorophenylalanine (50-1,000 microM), decreased the stimulatory effect of concanavalin A, serotonin (0.5-100 microM) and 8-hydroxy-2-(di-n-propylamino)tetralin (1-100 microM) reverted the effect of p-chlorophenylalanine (1,000 microM). The serotonin reuptake blockers zimelidine, imipramine and clomipramine decreased concanavalin A-induced proliferation. The concentrations of serotonin and noradrenaline increased in lymphocytes cultured in the presence of concanavalin A, probably as a mechanism for modifying the final effect on proliferation. The present results indicate that 5-HT(1A) receptors play a stimulatory role on rat blood lymphocytes, and they interact in a parallel and opposite manner with beta-adrenergic receptors. Furthermore, endogenous serotonin is relevant in displaying its stimulatory effect.
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Affiliation(s)
- Telésfora Sempere
- Laboratorio de Neuroquímica, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
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199
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La Cava A, Alviggi C, Matarese G. Unraveling the multiple roles of leptin in inflammation and autoimmunity. J Mol Med (Berl) 2004; 82:4-11. [PMID: 14556053 DOI: 10.1007/s00109-003-0492-1] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2003] [Accepted: 08/18/2003] [Indexed: 10/26/2022]
Abstract
Initially described as an antiobesity hormone, leptin has subsequently been shown also to influence hematopoiesis, thermogenesis, reproduction, angiogenesis, and immune homeostasis. Leptin links nutritional status and proinflammatory T helper 1 immune responses, and the decrease in leptin plasma concentration during food deprivation leads to impaired immune function. This review focuses on the multiple roles of leptin in chronic inflammation and autoimmunity and suggests new possible therapeutic implications for leptin modulators.
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Affiliation(s)
- Antonio La Cava
- Department of Medicine, University of California-Los Angeles, Los Angeles, CA 90095-1670, USA
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200
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Fantuzzi G, Banda NK, Guthridge C, Vondracek A, Kim SH, Siegmund B, Azam T, Sennello JA, Dinarello CA, Arend WP. Generation and characterization of mice transgenic for human IL-18-binding protein isoform a. J Leukoc Biol 2003; 74:889-96. [PMID: 12960225 DOI: 10.1189/jlb.0503230] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Interleukin (IL)-18 binding protein (IL-18BP) is a natural inhibitor of the pleiotropic cytokine IL-18. To study the role of IL-18BP in modulating inflammatory responses in vivo, mice transgenic for human IL-18BP isoform a (IL-18BP-Tg) were generated. The transgene was expressed at high levels in each organ examined. High levels of bioactive human IL-18BPa were detectable in the circulation of IL-18BP-Tg mice, which were viable, fertile, and had no tissue or organ abnormality. The high levels of IL-18BP in the transgenic mice were able to completely neutralize the interferon-gamma (IFN-gamma)-inducing activity of exogenously administered IL-18. Following administration of endotoxin, with or without prior sensitization with heat-inactivated Propionibacterium acnes, IL-18BP-Tg mice produced significantly lower serum levels of IFN-gamma and macrophage-inflammatory protein-2 compared with nontransgenic littermates. Significantly reduced production of IFN-gamma in response to endotoxin was also observed in cultures of IL-18BP-Tg splenocytes. Finally, IL-18BP-Tg mice were completely protected in a model of hepatotoxicity induced by administration of concanavalin A. These results indicate that high endogenous levels of IL-18BP in trangenic mice effectively neutralize IL-18 and are protective in response to different inflammatory stimuli.
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Affiliation(s)
- Giamila Fantuzzi
- Department of Medicine, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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