Inflammation-induced Proliferation Research Articles

Targeting Store-Operated Calcium Entry Regulates the Inflammation-Induced Proliferation and Migration of Breast Cancer Cells.

Persistent challenges complicating the treatment of breast cancer remain, despite some recent undeniable successes. Sufficient evidence currently exists demonstrating the crucial role of inflammation, characterized by the enhanced activation of Toll-like receptor 4 (TLR4) and the COX-2/PGE2 pathway, in the migration and proliferation of breast cancer cells. Interestingly, the store-operated calcium entry (SOCE) pathway was shown to be essential for the TLR4 activity and COX-2 expression in immune cells such as macrophages and microglia. However, whether SOCE influences inflammatory signaling and the inflammation-induced proliferation and migration of breast cancer cells is still unknown. Thus, the current study intended to delineate the role of SOCE in the TLR4-induced inflammation, migration, and proliferation of breast cancer cells. To this end, MDA-MB-231 breast cancer cells were treated with lipopolysaccharide (LPS) to activate TLR4, BTP2 to inhibit SOCE, and Thapsigargin to induce SOCE. Following these treatments, several experiments were conducted to evaluate the proliferation and migration rates of the MDA-MB-231 cells and the expression of several inflammatory and oncogenic genes, including COX-2, PGE2, IL-6, IL-8, and VEGF. Different techniques were used to achieve the aims of this study, including qRT-PCR, Western blotting, ELISA, MTT, and wound healing assays. This study shows that SOCE inhibition using BTP2 suppressed the LPS-induced migration and proliferation of breast cancer cells. Additionally, treatment with LPS caused approximately six- and three-fold increases in COX-2 mRNA and protein expression, respectively, compared to the controls. The LPS-induced elevations in the COX-2 mRNA and protein levels were suppressed by BTP2 to the control levels. In addition to its effect on COX-2, BTP2 also suppressed the LPS-induced productions of PGE2, IL-6, IL-8, and VEGF. Conversely, SOCE induction using Thapsigargin enhanced the LPS-induced inflammation, migration, and proliferation of breast cancer cells. Collectively, these results provide evidence for the potentially important role of SOCE in inflammation-induced breast cancer progression processes. Thus, we argue that the current study may provide novel targets for designing new therapeutic approaches for the treatment of breast cancer.

Regulation of S100As Expression by Inflammatory Cytokines in Chronic Lymphocytic Leukemia.

The calcium-binding proteins S100A4, S100A8, and S100A9 are upregulated in chronic lymphocytic leukemia (CLL), while the S100A9 promotes NF-κB activity during disease progression. The S100-protein family has been involved in several malignancies as mediators of inflammation and proliferation. The hypothesis of our study is that S100A proteins are mediators in signaling pathways associated with inflammation-induced proliferation, such as NF-κB, PI3K/AKT, and JAK/STAT. The mononuclear cells (MNCs) of CLL were treated with proinflammatory IL-6, anti-inflammatory IL-10 cytokines, inhibitors of JAK1/2, NF-κB, and PI3K signaling pathways, to evaluate S100A4, S100A8, S100A9, and S100A12 expression as well as NF-κB activation by qRT-PCR, immunocytochemistry, and immunoblotting. The quantity of S100A4, S100A8, and S100A9 positive cells (p < 0.05) and their protein expression (p < 0.01) were significantly decreased in MNCs of CLL patients compared to healthy controls. The S100A levels were generally increased in CD19+ cells compared to MNCs of CLL. The S100A4 gene expression was significantly stimulated (p < 0.05) by the inhibition of the PI3K/AKT signaling pathway in MNCs. IL-6 stimulated S100A4 and S100A8 protein expression, prevented by the NF-κB and JAK1/2 inhibitors. In contrast, IL-10 reduced S100A8, S100A9, and S100A12 protein expressions in MNCs of CLL. Moreover, IL-10 inhibited activation of NF-κB signaling (4-fold, p < 0.05). In conclusion, inflammation stimulated the S100A protein expression mediated via the proliferation-related signaling and balanced by the cytokines in CLL.

Midkine-Notch2 Pathway Mediates Excessive Proliferation of Airway Smooth Muscle Cells in Chronic Obstructive Lung Disease

Inflammation-induced proliferation of airway smooth muscle cells (ASMCs) and subsequent airway remodeling is a hallmark of chronic obstructive lung disease (COPD). The role of midkine (MK) in COPD is unclear. In this work, we explored the role of MK-Notch2 signaling in COPD by inhibiting the expression of MK using lentivirus shRNA in ASMCs in vitro and instillation of AAV9-MK in the airway of a COPD rat model in vivo. The results demonstrated that LPS decreased ASMC migration and proliferation, increased apoptosis and induced the expression of MK and Notch2 signaling molecules. Inhibition of MK exacerbated the changes in migration and proliferation but decreased the expression of MK and Notch2 signaling molecules. Rats treated with smoke fumigation and LPS showed features of COPD. The small airways of COPD rats were remodeled and lung function was significantly reduced. The expressions of TGF-β, ICAM-1, HA, MMP-9, PC-III, and LN in BALF and the expression of MK and Notch2 signaling molecules were significantly increased in the COPD rats compared with controls. Inhibition of MK reversed these changes. In conclusion, the MK-Notch2 pathway plays a key role in airway remodeling induced by ASMC proliferation. Targeting the MK-Notch2 pathway may be a new strategy for improving airway remodeling and preventing progressive decline of pulmonary function in COPD.

Dclk1 in tuft cells promotes inflammation-driven epithelial restitution and mitigates chronic colitis.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by defective intestinal barrier integrity toward the microbiota and epithelial damage. Double cortin-like kinase 1 (Dclk1), a marker ofintestinal tuft cells, can regulate tissue regenerative responses, but its role in epithelial repair during bacterial-dependent chronic colitis is unclear. We addressed this question using our recently developed mouse model of spontaneous microbiota-dependent colitis induced by mucin-type O-glycan deficiency (DKO), which recapitulates most features of human UC. We generated DKO mice lacking intestinal epithelial Dclk1 (DKO;Dclk1ΔIEC) and analyzed colitis onset and severity using clinical and histologic indices, immune responses by qPCR and immunostaining, and epithelial responses using proliferation markers and organoid culture. We found 3-4-week-old DKO;Dclk1ΔIEC mice developed worsened spontaneous colitis characterized by reduced body weight, loose stool, severe colon thickening, epithelial lesions, and inflammatory cell infiltrates compared with DKO mice. The primary defect was an impaired epithelial proliferative response during inflammation. Dclk1 deficiency also reduced inflammation-induced proliferation and growth of colon organoids ex vivo. Mechanistically, Dclk1 expression was important for inflammation-induced Cox2 expression and prostaglandin E2 (PGE2) production in vivo, and PGE2 rescued proliferative defects in Dclk1-deficient colonic organoids. Although tuft cells were expanded in both DKO and DKO;Dclk1ΔIEC relative to WT mice, loss of Dclk1 was associated with reduced tuft cell activation (i.e., proliferation) during inflammation. Similar results were found in DKO vs. DKO;Dclk1ΔIEC mice at 3-6 months of age. Our results support that tuft cells, via Dclk1, are important responders to bacterial-induced colitis by enhancing epithelial repair responses, which in turn limits bacterial infiltration into the mucosa.

Inhibition of chronic prostate inflammation by hyaluronic acid through an immortalized human prostate stromal cell line model.

Benign prostatic hyperplasia (BPH) is the most common urologic disease among elderly men. A well-established in vitro cell model is required to determine the therapeutic mechanism of BPH inflammation. In this study, we attempted to establish an immortalized human prostate stromal cell line by transfecting with HPV-16 E6/E7 and designated as ihPSC. No significant difference was found in fibroblast-like morphology between primary hPSC and ihPSC. The ihPSC possessed a significantly higher cell proliferation rate than primary hPSC. The prostate-specific markers and proteins including cytoskeleton (α-SMA and vimentin) and smooth muscle (calponin), especially the androgen receptor (AR) were also examined in ihPSC, almost identical to the primary hPSC. To create an in vitro model featuring chronic prostatic inflammation, ihPSC was stimulated with IFN-γ+IL-17 and then treated with the high molecular weight hyaluronic acid hylan G-F 20 as an alternative strategy for inhibiting BPH inflammation. Hylan G-F 20 could dose-dependently diminish the inflammation-induced proliferation in ihPSC. The enhanced expressions of inflammatory molecules including IL-1β, IL-6, IL-8, cyclooxygenase 2 (COX2), inducible nitrogen oxide synthase (iNOS), and Toll-like receptor 4 (TLR4) were all abolished by hylan G-F 20. For inflammatory signaling, hylan G-F 20 can also diminish the IFN-γ+IL-17-increased expression of iNOS and p65 in ihPSC. These findings suggest that ihPSC could provide a mechanism-based platform for investigating prostate inflammation. The hylan G-F 20 showed strong anti-inflammatory effects by decreasing inflammatory cytokines and signalings in the ihPSC, indicating its therapeutic potentials in BPH treatment in the future.

MP17-03 INFLAMMATION-INDUCED PROSTATIC ENLARGEMENT AND PROLIFERATION OF PROSTATE EPITHELIAL CELLS IS REDUCED BY GROWTH HORMONE-RELEASING HORMONE (GHRH) ANTAGONISTS THROUGH THE INHIBITION OF EPITHELIAL-TO-MESENCHYMAL TRANSITION

You have accessJournal of UrologyBenign Prostatic Hyperplasia: Basic Research & Pathophysiology1 Apr 2017MP17-03 INFLAMMATION-INDUCED PROSTATIC ENLARGEMENT AND PROLIFERATION OF PROSTATE EPITHELIAL CELLS IS REDUCED BY GROWTH HORMONE-RELEASING HORMONE (GHRH) ANTAGONISTS THROUGH THE INHIBITION OF EPITHELIAL-TO-MESENCHYMAL TRANSITION Petra Popovics, Andrew Schally, Luis Salgueiro, Krisztina Kovacs, and Ferenc Rick Petra PopovicsPetra Popovics More articles by this author , Andrew SchallyAndrew Schally More articles by this author , Luis SalgueiroLuis Salgueiro More articles by this author , Krisztina KovacsKrisztina Kovacs More articles by this author , and Ferenc RickFerenc Rick More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.592AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The pathogenesis of benign prostatic hyperplasia (BPH) has been associated with various factors including hormonal imbalance, inflammation-induced cell proliferation and epithelial-to-mesenchymal transition. We have previously demonstrated that prostatic GHRH and its receptors are upregulated in a rat testosterone-induced BPH model and GHRH antagonists suppress the levels of proinflammatory cytokines. Based on these findings, we investigated the role of GHRH in inflammation-induced proliferation of prostate epithelial cells in vitro and prostate enlargement in experimental autoimmune prostatitis. METHODS Autoimmune inflammation in the prostates of Balb/c mice was induced by subcutaneous injections of rat male tissue homogenate. Changes in prostate volume were measured with the VEVO® 1100 ultrasound imaging system. Human BPH-1 and primary prostate epithelial cells were used in matrigel-embedded 3D cultures and average sphere diameters were evaluated. Chronic inflammation was mimicked by treating cells with THP-1 macrophage-conditioned medium or Il-17A, whereas EMT was triggered with TGF-β1 or TGF-β2 peptides. The role of secreted GHRH in inflammation-induced proliferation was determined by using GHRH antagonists developed in our lab. Changes in the protein levels were determined by western blot. RESULTS Experimental autoimmune prostatitis increased the volume of the ventral prostate by 92% at week 8 compared to control (p<0.001). A 1-month daily treatment with GHRH antagonists caused a significant, 48% reduction in prostate volume. Macrophage-conditioned medium induced a 26% increase (p<0.001) in the average diameter of cells and elevation in the expression of mesenchymal markers. The mRNA and protein expression of GHRH were significantly increased by macrophage-conditioned medium. GHRH antagonist reduced inflammation- and TGF-β2-induced increase in diameter by 64% (p<0.01) and by 67% (p<0.001), respectively, and reduced the expression of n-cadherin. The stimulatory effect of TGF-β2 was abolished when GHRH receptor expression was silenced by stable transfection of shRNA. IL-17A stimulation of the growth of primary epithelial cells were also significantly reduced by GHRH antagonists. CONCLUSIONS Our results indicate that GHRH is a key factor in prostatic inflammation-induced prostate enlargement and EMT and suggest that GHRH antagonists have beneficial effects in chronic prostatitis and BPH. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e212 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Petra Popovics More articles by this author Andrew Schally More articles by this author Luis Salgueiro More articles by this author Krisztina Kovacs More articles by this author Ferenc Rick More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

MP44-11 GROWTH HORMONE-RELEASING HORMONE (GHRH) ANTAGONISTS REDUCE INFLAMMATION- AND TRANSFORMING GROWTH FACTOR (TGF)-?2-INDUCED PROLIFERATION OF HUMAN BPH-1 PROSTATE EPITHELIAL CELLS GROWN IN 3D CULTURE

You have accessJournal of UrologyBenign Prostatic Hyperplasia: Basic Research & Pathophysiology1 Apr 2016MP44-11 GROWTH HORMONE-RELEASING HORMONE (GHRH) ANTAGONISTS REDUCE INFLAMMATION- AND TRANSFORMING GROWTH FACTOR (TGF)-?2-INDUCED PROLIFERATION OF HUMAN BPH-1 PROSTATE EPITHELIAL CELLS GROWN IN 3D CULTURE Petra Popovics, Andrew V. Schally, Roberto Perez, Rhenzi Cai, and Ferenc G. Rick Petra PopovicsPetra Popovics More articles by this author , Andrew V. SchallyAndrew V. Schally More articles by this author , Roberto PerezRoberto Perez More articles by this author , Rhenzi CaiRhenzi Cai More articles by this author , and Ferenc G. RickFerenc G. Rick More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.267AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Benign prostatic hyperplasia (BPH) is frequently associated with chronic inflammation. Epithelial-to-mesenchymal transition (EMT) has been recently indicated as a major factor in the pathogenesis of BPH. Evidence also suggests that inflammatory cytokines may induce BPH. Hypothalamic neuropeptides, GHRH, luteinizing hormone-releasing hormone (LHRH) and their receptors are expressed in experimental models of BPH in which antagonists of GHRH and LHRH have been shown to suppress the levels of proinflammatory cytokines and alter the expression of genes related to EMT. These findings imply a role of GHRH/LHRH in the development of prostatitis, however, this has not been investigated to date. METHODS Human BPH-1 prostatic cell line was used to generate matrigel-embedded 3D cultures in which average sphere diameters were evaluated. Chronic inflammation was induced by treating cells with THP-1 macrophage-conditioned medium whereas EMT was triggered with TGF-ß1 or TGF-ß2 peptides. The role of secreted LHRH and GHRH in inflammation-induced proliferation was determined by using the LHRH antagonist, degarelix, and a specific GHRH antagonist developed in our lab. The presence of receptors for GHRH and LHRH was confirmed in 3D cultures by immunocytochemistry and quantitative RT-PCR. RESULTS BPH-1-derived spherical structures expressed cell membrane receptors for LHRH and GHRH. Macrophage-conditioned medium induced a 26% increase (P<0.001) in the average diameter of cells and a 2-fold elevation in the expression of the EMT markers N-cadherin (p<0.01) and Snail (p<0.001) as detected by qPCR. The expression of GHRH was also increased 2.7-fold (p<0.001), whereas mRNA levels of LHRH were slightly reduced (ns). GHRH antagonist reduced inflammation-induced increase in diameter by 64% (P<0.01), while no significant change was observed after degarelix treatment. TGF-ß2 increased average sphere diameter by 32%, but this effect was reduced by 67% by the GHRH antagonist (P<0.001). In contrast, TGF-ß1 did not significantly affect sphere diameter. CONCLUSIONS This study identifies GHRH as an important factor in inflammation-induced proliferation and TGF-ß2-triggered EMT of prostate epithelial cells and suggests the merit of further investigation to elucidate the effects of GHRH antagonists in the reduction of inflammation-induced BPH. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e602-e603 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Petra Popovics More articles by this author Andrew V. Schally More articles by this author Roberto Perez More articles by this author Rhenzi Cai More articles by this author Ferenc G. Rick More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Abstract 566: Broad-Spectrum Chemokine Inhibition Blocks Inflammation-Induced Pathological Angiogenesis but Preserves Hypoxia-Driven Physiological Angiogenesis

Introduction: Angiogenesis is critical for survival and in the regenerative response to tissue hypoxia. An imbalance in its regulation causes excessive angiogenesis, exacerbating inflammatory diseases such as cancer and atherosclerosis. Chemokines from the CC-chemokine class are increasingly implicated in the regulation of inflammatory pathological angiogenesis but, in contrast, have a minimal role in hypoxia-driven physiological angiogenesis. Inhibition of CC-chemokines may therefore differentially regulate angiogenesis depending on the pathophysiological context. The ‘35K’ protein uniquely inhibits the CC chemokine class and does not affect chemokines from other classes. Aim: To determine the effect of CC-chemokine inhibition with 35K on inflammation-induced angiogenesis and hypoxia-driven angiogenesis using human coronary artery endothelial cells (EC) in in vitro angiogenic functional assays. Results: Matrigel tubule formation was strikingly inhibited (95.8%, p&lt;0.001) by 35K (50nM) under the inflammatory stimuli of macrophage conditioned media. The addition of 35K also reduced inflammation-induced proliferation by 88.3% (p&lt;0.001). Furthermore, we found the addition of 35K suppressed inflammation stimulated EC migration speed by 15.8% (p&lt;0.05). By contrast, in hypoxia, 35K (50nM) reduced tubule formation by 45.2% (p&lt;0.01), indicating a relative preservation of tubulogenesis in hypoxia compared to inflammation. Consistent with this, in hypoxia, 35K reduced proliferation by 43.8% (p&lt;0.05). Moreover, the speed of EC migration was completely preserved under hypoxic conditions following the addition of 35K. Mechanistic studies supported our functional observations. Angiogenic growth factor, VEGF, was inhibited (53.4%) by 35K (200nM) under inflammatory conditions yet was augmented in hypoxia (31.5%). 35K also decreased key angiogenesis transcription factors, p65 (37.3%) and HIF-1α (87.3%) in inflammation. Conclusion: Broad-spectrum chemokine inhibition by 35K blocks inflammation-induced angiogenic processes, whilst preserving hypoxia-driven angiogenesis. This may present as a therapeutic strategy to reduce pathological angiogenic disease, without the severe side effects of current therapies.

A physiological concentration of glucocorticoid inhibits the pro-inflammatory cytokine-induced proliferation of adult rat cardiac fibroblasts: Roles of extracellular signal-regulated kinase 1/2 and nuclear factor-κB

1. Inflammation-induced proliferation of cardiac fibroblasts plays an important role in cardiac remodelling. Pharmacological doses of exogenous glucocorticoids (GC) are the most effective therapy for inflammatory diseases. Similarly, physiological concentrations of endogenous GC have recently been shown to have anti-inflammatory effects. Therefore, the aim of the present study was to determine whether a physiological concentration of GC could inhibit pro-inflammatory cytokine-stimulated proliferation of cardiac fibroblasts and to explore the mechanisms involved. 2. Cardiac fibroblasts were isolated from adult male Sprague-Dawley rats and cell proliferation was measured using a CCK-8 kit. Western blotting was used to detect protein expression of extracellular-regulated kinase (ERK) 1/2 and nuclear factor (NF)-κB. 3. Cardiac fibroblast proliferation was significantly increased by tumour necrosis factor-α, interleukin (IL)-1β and angiotensin II and was accompanied by upregulated protein expression of ERK1/2 and NF-κB. A physiological concentration of hydrocortisone (127 ng/mL) not only inhibited the proliferation of cardiac fibroblasts, but also suppressed activation of ERK1/2 and NF-κB. These effects of hydrocortisone were abrogated by the glucocorticoid receptor (GR) antagonist RU-486 (100 nmol/L). Furthermore, inflammation-induced cardiac fibroblast proliferation was also blocked by the mitogen-activated protein kinase kinase 1/2 inhibitor U0126 (100 nmol/L) and the NF-κB inhibitor pyrrolidine dithiocarbamate (1 μmol/L). Cytokine-induced ERK1/2 phosphorylation and cyclin D1 expression were attenuated by U0126, suggesting that the ERK1/2 and NF-κB signalling pathways were involved in cardiac fibroblast proliferation. 4. In conclusion, the results of the present study indicate that a physiological concentration of hydrocortisone can inhibit inflammation-induced proliferation of cardiac fibroblasts by preventing the activation of ERK1/2 and NF-κB.

Proliferation modulates intestinal smooth muscle phenotype in vitro and in colitis in vivo

Intestinal inflammation causes an increased intestinal wall thickness, in part, due to the proliferation of smooth muscle cells, which impairs the contractile phenotype elsewhere. To study this, cells from the circular muscle layer of the rat colon (CSMC) were isolated and studied, both in primary culture and after extended passage, using quantitative PCR, Western blot analysis, and immunocytochemistry. By 4 days in vitro, both mRNA and protein for the smooth muscle marker proteins α-smooth muscle actin, desmin, and SM22-α were reduced by >50%, and mRNA for cyclin D1 was increased threefold, evidence for modulation to a proliferative phenotype. Continued growth caused significant further decrease in expression, evidence that phenotypic loss in CSMC was proportional to the extent of proliferation. In CSMC isolated at day 2 of trinitrobenzene sulfonic acid-induced colitis, flow cytometry and Western blotting showed that these differentiated markers were reduced in mitotic CSMC, while similar to control in nonmitotic CSMC. By day 35 post-trinitrobenzene sulfonic acid, when inflammation has resolved, CSMC were hypertrophic, but, nonetheless, showed markedly decreased expression of smooth muscle protein markers per cell. In vitro, day 35 CSMC displayed an accelerated loss of phenotype and increased thymidine uptake in response to serum or PDGF-BB. Furthermore, carbachol-induced expression of phospho-AKT (a marker of cholinergic response) was lost from day 35 CSMC in vitro, while retained in control cells. Therefore, proliferation reduces the expression of smooth-muscle-specific markers in CSMC, possibly leading to altered contractility. However, inflammation-induced proliferation in vivo also causes lasting changes that include unexpected priming for an exaggerated response to proliferative stimuli. Identification of the molecular mechanisms of intestinal smooth muscle cell phenotypic modulation will be helpful in reducing the detrimental effects of inflammation.

Interleukin-10-independent anti-inflammatory actions of glucagon-like peptide 2

Glucagon-like peptide 2 (GLP-2) is an important intestinal growth factor with anti-inflammatory activity. We hypothesized that GLP-2 decreases mucosal inflammation and the associated increased epithelial proliferation by downregulation of Th1 cytokines attributable to reprogramming of lamina propria immune regulatory cells via an interleukin-10 (IL-10)-independent pathway. The effects of GLP-2 treatment were studied using the IL-10-deficient (IL-10(-/-)) mouse model of colitis. Wild-type and IL-10(-/-) mice received saline or GLP-2 (50 microg/kg sc) treatment for 5 days. GLP-2 treatment resulted in significant amelioration of animal weight loss and reduced intestinal inflammation as assessed by histopathology and myeloperoxidase levels compared with saline-treated animals. In colitis animals, GLP-2 treatment also reduced crypt cell proliferation and crypt cell apoptosis. Proinflammatory (IL-1beta, TNF-alpha, IFN-gamma,) cytokine protein levels were significantly reduced after GLP-2 treatment, whereas IL-4 was significantly increased and IL-6 production was unchanged. Fluorescence-activated cell sorting analysis of lamina propria cells demonstrated a decrease in the CD4(+) T cell population following GLP-2 treatment in colitic mice and an increase in CD11b(+)/F4/80(+) macrophages but no change in CD25(+)FoxP3 T cells or CD11c(+) dendritic cells. In colitis animals, intracellular cytokine analysis demonstrated that GLP-2 decreased lamina propria macrophage TNF-alpha production but increased IGF-1 production, whereas transforming growth factor-beta was unchanged. GLP-2-mediated reduction of crypt cell proliferation was associated with an increase in intestinal epithelial cell suppressor of cytokine signaling (SOCS)-3 expression and reduced STAT-3 signaling. This study shows that the anti-inflammatory effects of GLP-2 are IL-10 independent and that GLP-2 alters the mucosal response of inflamed intestinal epithelial cells and macrophages. In addition, the suggested mechanism of the reduction in inflammation-induced proliferation is attributable to GLP-2 activation of the SOCS-3 pathway, which antagonizes the IL-6-mediated increase in STAT-3 signaling.

Involvement of inducible nitric oxide synthase in inflammation-induced dopaminergic neurodegeneration

The loss of dopaminergic neurones in the substantia nigra with Parkinson’s disease may result from inflammation-induced proliferation of microglia and reactive macrophages expressing inducible nitric oxide synthase (iNOS). We have investigated the effects of the supranigral administration of lipopolysaccharide on iNOS-immunoreactivity, 3-nitrotyrosine formation and tyrosine hydroxylase-immunoreactive neuronal number, and retrogradely labelled fluorogold-positive neurones in the ventral mesencephalon in male Wistar rats. Following supranigral lipopolysaccharide injection, 16–18 h previously, there was intense expression of NADPH-diaphorase and iNOS-immunoreactivity in non-neuronal, macrophage-like cells. This was accompanied by intense expression of glial fibrillary acidic protein-immunoreactive astrocytosis in the substantia nigra. There were also significant reductions in the number of tyrosine hydroxylase(50–60%)- and fluorogold (65–75%)-positive neurones in the substantia nigra. In contrast, tyrosine hydroxylase-immunoreactivity in the ventral tegmental area was not altered. Pre-treatment of animals with the iNOS inhibitor, S-methylisothiourea (10 mg kg −1, i.p.), led to a significant reduction of lipopolysaccharide-induced cell death. Similar reduction of tyrosine hydroxylase-immunoreactivity and fluorogold-labelled neurones in the substantia nigra following lipopolysaccharide administration suggests dopaminergic cell death rather than down-regulation of tyrosine hydroxylase. We conclude that the expression of iNOS- and 3-nitrotyrosine-immunoreactivity and reduction of cell death by S-methylisothiourea suggest the effects of lipopolysaccharide may be nitric oxide-mediated, although other actions of lipopolysaccharide (independent of iNOS induction) cannot be ruled out.