Macrophage infiltration is a negative prognostic factor for most cancers but gastrointestinal tumors seem to be an exception. The effect of macrophages on cancer progression depends on their phenotype, which may vary between M1 (pro-inflammatory, defensive) to M2 (tolerogenic, pro-tumoral). Gastrointestinal cancers often become an ectopic source of gastrins and macrophages present receptors for these peptides. The aim of the present study is to analyze whether gastrins can affect the pattern of macrophage infiltration in colorectal tumors. We have evaluated the relationship between gastrin expression and the pattern of macrophage infiltration in samples from colorectal cancer and the influence of these peptides on the phenotype of macrophages differentiated from human peripheral monocytes in vitro. The total number of macrophages (CD68+ cells) was similar in tumoral and normal surrounding tissue, but the number of M2 macrophages (CD206+ cells) was significantly higher in the tumor. However, the number of these tumor-associated M2 macrophages correlated negatively with the immunoreactivity for gastrin peptides in tumor epithelial cells. Macrophages differentiated from human peripheral monocytes in the presence of progastrin showed lower levels of M2-markers (CD206, IL10) with normal amounts of M1-markers (CD86, IL12). Progastrin induced similar effects in mature macrophages treated with IL4 to obtain a M2-phenotype or with LPS plus IFN? to generate M1-macrophages. Macrophages differentiated in the presence of progastrin presented a reduced expression of Wnt ligands and decreased the number and increased cell death of co-cultured colorectal cancer epithelial cells. Our results suggest that progastrin inhibits the acquisition of a M2-phenotype in human macrophages. This effect exerted on tumor associated macrophages may modulate cancer progression and should be taken into account when analyzing the therapeutic value of gastrin immunoneutralization.
The potential cardiovascular (CV) toxicity associated with combined antiretroviral therapy (cART) has been attributed mainly to the nucleoside reverse transcriptase inhibitors abacavir and didanosine. However, the other two components of cART-non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs)-may also be implicated, either directly or by influencing the action of the other drugs. This study evaluates the acute direct effects of the NNRTIs efavirenz and nevirapine and one of the most widely employed PIs, lopinavir, on leucocyte-endothelium interactions, a hallmark of CV disease.
ER stress is associated with a growing number of liver diseases, including drug-induced hepatotoxicity. The non-nucleoside analogue reverse transcriptase inhibitor Efavirenz, a cornerstone of the multidrug strategy employed to treat HIV1 infection, has been related to the development of various adverse events, including metabolic disturbances and hepatic toxicity, the mechanisms of which remain elusive. Recent evidence has pinpointed a specific mitochondrial effect of Efavirenz in human hepatic cells. This study assesses the induction of ER stress by Efavirenz in the same model and the implication of mitochondria in this process.
Macrophages, which exhibit great plasticity, are important components of the inflamed tissue and constitute an essential element of regenerative responses. Epithelial Wnt signalling is involved in mechanisms of proliferation and differentiation and expression of Wnt ligands by macrophages has been reported. We aim to determine whether the macrophage phenotype determines the expression of Wnt ligands, the influence of the macrophage phenotype in epithelial activation of Wnt signalling and the relevance of this pathway in ulcerative colitis. Human monocyte-derived macrophages and U937-derived macrophages were polarized towards M1 or M2 phenotypes and the expression of Wnt1 and Wnt3a was analyzed by qPCR. The effects of macrophages and the role of Wnt1 were analyzed on the expression of ?-catenin, Tcf-4, c-Myc and markers of cell differentiation in a co-culture system with Caco-2 cells. Immunohistochemical staining of CD68, CD206, CD86, Wnt1, ?-catenin and c-Myc were evaluated in the damaged and non-damaged mucosa of patients with UC. We also determined the mRNA expression of Lgr5 and c-Myc by qPCR and protein levels of ?-catenin by western blot. Results show that M2, and no M1, activated the Wnt signaling pathway in co-culture epithelial cells through Wnt1 which impaired enterocyte differentiation. A significant increase in the number of CD206+ macrophages was observed in the damaged mucosa of chronic vs newly diagnosed patients. CD206 immunostaining co-localized with Wnt1 in the mucosa and these cells were associated with activation of canonical Wnt signalling pathway in epithelial cells and diminution of alkaline phosphatase activity. Our results show that M2 macrophages, and not M1, activate Wnt signalling pathways and decrease enterocyte differentiation in co-cultured epithelial cells. In the mucosa of UC patients, M2 macrophages increase with chronicity and are associated with activation of epithelial Wnt signalling and diminution in enterocyte differentiation.
The induction of intestinal trefoil factor (ITF) has been reported to depend on hypoxia-inducible factor-1 (HIF-1). Nitric oxide modulates HIF-1 activity. The present study aims to analyze the role of nitric oxide in jejunum damage induced by indomethacin and its ability to modulate epithelial function through the expression of ITF.
Gastric mucosal inflammation is frequently associated with hypergastrinemia, and a correlation exists between the level of gastrin and degree of gastritis. We have previously observed that gastrin promotes leukocyte-endothelial interactions and contributes to Helicobacter-induced inflammation in the rat mesentery. In the present study, we aimed to evaluate a possible proinflammatory activity of gastrin in humans. The interaction between human leukocytes [U-937 cells, peripheral blood polymorphonuclear (PMN), and peripheral blood mononuclear (PBMC) cells] and human umbilical vein endothelial cells (HUVEC) was analyzed in static and dynamic conditions. The endothelial expression of adhesion molecules [P-selectin, E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule (VCAM)-1] was analyzed by flow cytometry and fluorescent microscopy screening. Gastrin increased the static adhesion of U-937 cells to HUVEC (1 h; 10(-9) M: 122 +/- 9%; 10(-8) M: 143 +/- 17%; 10(-7) M: 162 +/- 14% vs. control, all P < 0.05). Incubation of HUVEC with gastrin (4 h) also increased PBMC rolling (vehicle: 63 +/- 12; 10(-9) M: 109 +/- 29; 10(-8) M: 141 +/- 24; 10(-7) M: 261 +/- 16 leukocytes/min, P < 0.05) and adhesion (vehicle: 3 +/- 2, 10(-9) M: 11 +/- 4, 10(-8) M: 17 +/- 5, 10(-7) M: 15 +/- 5 leukocytes/mm(2), all P < 0.05) in the parallel-plate flow chamber. Treatment of PBMC with gastrin had no effects. The cholecystokinin (CCK)-2 receptor antagonist (L-365,260, 10(-7) M) prevented the effects of gastrin. P-selectin and VCAM-1 expression were enhanced by gastrin, and neutralizing antibodies against these molecules prevented PBMC rolling and adhesion. Gastrin did not affect the interactions between HUVEC and PMN. Gastrin induces interactions between human mononuclear leukocytes and endothelial cells through the activation of CCK-2 receptors and the enhancement of endothelial P-selectin and VCAM-1.
Trefoil (TFF) peptides are involved in gastrointestinal mucosal restitution. An hypoxia inducible factor 1 (HIF-1)-dependent induction of TFF genes has been reported in gastric epithelial cells. Nitric oxide (NO) is associated with mucosal damage and modulates HIF-1 activity. The aim of the present study was to analyze the role of iNOS-derived NO in HIF-1alpha stabilization and TFF gene expression in damaged gastric mucosa. Aspirin caused gastric injury that peaked 6 h after dosing and returned to normality at 24 h. iNOS mRNA expression occurs in the corpus in parallel with damage. Blockade of iNOS activity did not modify gastric lesions induced by aspirin but delayed mucosal healing. Aspirin induced HIF-1alpha stabilization and TFF2 mRNA up-regulation in the mucosa, but these effects were diminished when iNOS activity was inhibited. Results obtained using a coculture setup showed that iNOS-derived NO from activated macrophages induced HIF-1alpha stabilization, TFF gene expression, and accelerated wound healing in cultured epithelial cells. Finally, transient silencing of endogenous HIF-1alpha in epithelial cells significantly undermined activated macrophage-induced TFF gene expression. Evidence suggests that the iNOS-derived NO associated with NSAID-induced gastric injury is implicated in mucosal restitution via the HIF-1-mediated induction of TFF genes.
Prospective study carried out on 24 consecutive patients with Crohns Disease, using sonography to assess changes caused by biological therapy and its relationship with the clinical-biological response. The Crohns Disease Activity Index, the plasma concentration of C-reactive protein and abdominal sonograms (to assess the thickness and Doppler flow grade of the bowel wall and to detect the presence of any complications) were carried out one week prior to the induction treatment and two weeks after. The biological therapy induced remission or a partial response in 46% and 25% of the patients, respectively. It also caused a significant reduction in the thickness of the bowel wall (P = 0.005) and Doppler flow (P = 0.02), leading to the disappearance of complications in 50% of the patients. Sonographic changes were significantly more marked in patients who achieved some type of clinical-biological response, in such a way that sonograms were improved in 65% (P = 0.001) and complications disappeared in 100% of patients (P = 0.005) compared to those patients who did not respond to treatment. However, sonographic normality was only achieved in five out of 17 (29%) reactive patients (P = 0.27). This fact may support the use of sonography as a technique for optimizing the biological treatment of Crohns Disease.
Inflammation is part of a complex biological response of vascular tissue to pathogens or damaged cells. First inflammatory cells attempt to remove the injurious stimuli and this is followed by a healing process mediated principally by phagocytosis of senescent cells. Hypoxia and p38-MAPK are associated with inflammation, and hypoxia inducible factor 1 (HIF-1) has been detected in inflamed tissues. We aimed to analyse the role of p38-MAPK and HIF-1 in the transcriptional regulation of CD36, a class B scavenger receptor, and its ligand thrombospondin (TSP-1) in macrophages and to evaluate the involvement of this pathway in phagocytosis of apoptotic neutrophils. We have also assessed HIF-1?, p38-MAPK and CD36 immunostaining in the mucosa of patients with inflammatory bowel disease. Results show that hypoxia increases neutrophil phagocytosis by macrophages and induces the expression of CD36 and TSP-1. Addition of a p38-MAPK inhibitor significantly reduced the increase in CD36 and TSP-1 expression provoked by hypoxia and decreased HIF-1? stabilization in macrophages. Transient transfection of macrophages with a miHIF-1?-targeting vector blocked the increase in mRNA expression of CD36 and TSP-1 during hypoxia and reduced phagocytosis, thus highlighting a role for the transcriptional activity of HIF-1. CD36 and TSP-1 were necessary for the phagocytosis of neutrophils induced by hypoxic macrophages, since functional blockade of these proteins undermined this process. Immunohistochemical studies revealed CD36, HIF-1? and p38-MAPK expression in the mucosa of patients with inflammatory bowel disease. A positive and significant correlation between HIF-1? and CD36 expression and CD36 and p38-MAPK expression was observed in cells of the lamina propria of the damaged mucosa. Our results demonstrate a HIF-1-dependent up-regulation of CD36 and TSP-1 that mediates the increased phagocytosis of neutrophils by macrophages during hypoxia. Moreover, they suggest that CD36 expression in the damaged mucosa of patients with inflammatory bowel disease depends on p38-MAPK and HIF-1 activity.
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