Effect of ulcerative colitis activity on plasma concentration of transforming growth factor beta1

Enhanced expression of transforming growth factor-beta1 (TGF-beta1) demonstrated in human colonic mucosa of patients with ulcerative colitis (UC), indicates its possible significance in the pathogenesis of this disease. The aim of this study was to evaluate plasma TGF-beta1 concentration in patients with different degrees of colonic mucosal injury, as a possible indicator of ulcerative colitis activity. TGF-beta1 concentration was measured with an enzyme immunoassay (EIA) in plasma of 45 patients with endoscopically confirmed UC. Values observed in UC patients (40.5+/-15.9 ng/ml) were significantly higher than in healthy people (18.3+/-11.6 ng/ml) and higher than in patients with irritable colon syndrome (ICS), (20.5+/-13.6 ng/ml). The highest plasma TGF-beta1 (58.6+/-112.1 ng/ml) was in patients with the severe UC course. TGF-beta1 level analysed in all UC patients revealed significant positive correlation with scored degree of mucosal injury (r=0.396;P<0.01). Among other possible laboratory markers of the disease activity, only C-reactive protein concentration demonstrated significant correlation. Enhanced production of TGF-beta1 can be related to inflammation activity. Measurement of plasma TGF-beta1 may be considered as a biomarker of the disease activity.     

Characterization of gastric mucosal prostaglandin E2 receptor

1. The binding characteristics of gastric mucosal prostaglandin (PG) E2 (PGE2) receptor were investigated using mucosal cell membranes from rat stomach. The binding was found to be dependent upon PGE2 and membrane protein concentration, the time of incubation and the pH of the mixture, being highest at pH 3.0. 2. Scatchard analysis of the binding data revealed a curvilinear plot with high affinity binding (Kd = 2 nM; Bmax = 0.106 pmol/mg protein) and low affinity binding (Kd = 319 nM; Bmax = 2.262 pmol/mg protein) sites. 3. Competitive displacement study indicated that the receptor was specific for PGs of the E series, as PGF2 alpha and 6-keto-PGF1 alpha failed to displace the PGE2. 4. The study is the first report to provide biochemical parameters of specific PGE receptors in rat gastric mucosa.     

Effects of exogenous prostaglandin E1 on human plasma norepinephrine level and dopamine-beta-hydrolyxase activity.

Effects of exogenous PG E1 on the level of human plasma norepinephrine (NE), dopamine-beta-hydroxylase (DBH) activity, cAMP, cGMP, free fatty acids (FFA) as well as pulse rate and blood pressure were studied. Significant decreases of blood pressure and increases of pulse rate were observed after 20 min of the infusion of 0.05 microgram/kg/min of PG E1. The level of plasma NE increased by 174% (p less than 0.005) after the infusion. However, the increase of DBH activity was not significant. There was a tendency of increase of plasma level of FFA. These results suggested that the infusion of PG E1 caused an augmented sympathetic nervous activity due to systemic hypotension induced by PG E1.     

Effects of 16,16-dimethyl prostaglandin E2 and indomethacin on leukotriene B4 and inflammation in rabbit colitis

The role of increased prostaglandin production and the effects of exogenous prostaglandins on inflammation of colitis are not established. We administered intramuscular 16,16-dimethyl prostaglandin E2 (DiM-PGE2) and indomethacin to rabbits with formalin immune-complex colitis and measured leukotriene B4 (LTB4), prostaglandin E2 (PGE2) and severity of inflammation. DiM-PGE2 (100 micrograms/kg/BID) reduced LTB4 production (from 401 +/- 108 to 216 +/- 58 pg/ml) and infiltration of neutrophils, mucosal necrosis, inflammatory exudate and edema (all P less than 0.05). Other studies determined that parenteral DiM-PGE2 did not reduce the initial chemical damage induced by formalin, suggesting that cytoprotection of chemical insult was not the mechanism of suppressed inflammation in the immune colitis model. Indomethacin (10 mg/kg/d) reduced endogenous PGE2 by 80%, but did not reduce leukotriene production or inflammation. Exogenous prostaglandins cause a dose-dependent suppression of inflammation in experimental colitis, by a mechanism other than cytoprotection of chemical-induced mucosal injury.     

Transforming growth factor beta1 and prostaglandin E2 concentrations are associated with bone formation markers in ulcerative colitis patients

Osteoporosis is a significant complication of a multifactoral etiology associated with inflammatory bowel disease. The aim of study was to evaluate the relationships between bone mineral density as well as bone turnover markers and inflammatory activity modulators (i.e., PGE2 and TGFbeta1) in ulcerative colitis (UC). Twenty-one active ulcerative colitis subjects and 14 healthy individuals were included into the study. We observed no significant differences in serum concentrations of osteoprotegerin and osteocalcin, as well as bone mineral density between UC patients and healthy individuals. Plasma concentrations of PGE2, TGFbeta1 and TNF-alpha were significantly higher in UC patients than in controls. Serum osteocalcin demonstrated a positive correlation with both serum PGE2 and plasma TGFbeta1. Moreover there was significant correlation between osteoprotegerin and TGFbeta1 as well as serum TNF-alpha concentrations. In conclusion a positive association between PGE2 and TGFbeta1 and bone formation markers-osteoprotegerin and osteocalcin, as well as a comparable BMD in UC patients and healthy individuals was shown. Our results may indicate that increase of PGE2 as well as TGFbeta1 concentrations may play a protective role against bone loss in ulcerative colitis patients.     

Lipopolysaccharide and silica-stimulated mononuclear cell prostaglandin production in ulcerative colitis

Basal, lipopolysaccharide (LPS) and silica-stimulated prostaglandin (PG) production were compared between peripheral blood mononuclear cells (PBMNC) from UC patients and healthy subjects (HS). Basal and LPS-stimulated PBMNC PGI2, but not PGE2, production was greater in UC. LPS stimulated both PGE2 and PGI2 by PBMNC from HS and UC patients. Silica stimulated production of both PGs by cells from HS but only PGE2 by cells from UC patients. The differences in responses to silica and LPS may result from differences in activation of NFkappaB or, alternatively, prior sensitisation to one of these agents. That PBMNC PGE2 production is not increased in UC, as it is in Crohn's disease, suggests that there are differences in PBMNC behaviour between these two diseases.     

Interaction of prostaglandins with blood plasma proteins. I. Binding of prostaglandin E 2 to human plasma proteins and its effect on the physiological activity of prostaglandin E 2 in vitro and in vivo

The binding of (PGE2) prostaglandin E2 to human plasma proteins was investigated by DEAE-Sephadex column chromatography and acrylamide gel electrophoresis, and quantitatively assessed by equilibrium dialysis. PGE2 added to human plasma in vitro was found to become mainly bound to plasma albumin. This binding was also demonstrated by adding PGE2 to human serum albumin solutions. The binding of PGE2 to human serum albumin inhibits the contraction-producing effect of PGE2 on the isolated gerbil colon in vitro. The depressor effect of PGE2 on the rat blood pressure was used to assess the in vivo effect of PGE2 albumin interaction. The blood pressure lowering activities of free and albumin-bound PGE2 were found to be the same when administered either intravenously or intraarterially. The significance of these observations with regard to estimation of PG concentration in whole blood or plasma, and their possible effects on PG metabolism is discussed.     

Effect of prostaglandin E2 on enzyme activity during parenteral feeding

It has been shown that prostaglandin E2 increases the activity of aspartate aminotransferase, alanine aminotransferase in the liver and striated muscle in parenteral feeding and increases the activity of aldolase in the liver but reduces it in the striated muscle. This demonstrates the enzymatic component in the mechanism of action of prostaglandin E2 on organ-tissue metabolism in parenteral feeding.     

Effects of epidermal growth factor on serum zinc and plasma prostaglandin E2 levels of mice with pressure sores

This work was undertaken to study the effects of systemic application of EGF on the plasma PGE2 and serum zinc levels of mice with pressure sores. The pressure sores were made on the hind limb of the mice by bilateral sciatic nerve neurotomy. Mice were injected IP, 1 μg EGF daily for ten days, begining on the 21st day after operation. EGF administration increased the serum zinc and plasma PGE2 levels compared with controls. These results indicate that EGF can be effective on wound healing by elevating the serum zinc and plasma PGE2 concentrations together with other physiological roles in cellular events.     

Mitochondrial respiratory chain in the colonic mucosal of patients with ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the large bowel. Its pathogenesis remains unclear, but it appears to result from a deregulated immune response, with infiltration of leukocytes into the mucosal interstitium. Several studies link oxidative stress and mitochondrial dysfunction to the pathogenesis of UC. Thus, the aim of this study was to evaluate the activities of mitochondrial respiratory chain complexes in the colonic mucosal of UC patients. Colonic biopsies were obtained from UC patients (n = 13). The control specimens were taken from patients without any history of inflammatory bowel disease (n = 8). Colon mucosal was removed by colonoscopy and homogenized. Mitochondrial respiratory chain complexes activities were then measured. Our results showed that the activity of complex I was not altered in UC patients, when compared to the control group. On the other hand, complexes II, III, and IV were decreased around 50–60% in the colonic mucosal of UC patients. Based on the present findings, we hypothesize that mitochondrial dysfunction may play a role in pathogenesis of UC.     

Effects of prostaglandin E2 and D2 on the release of vasopressin and oxytocin

The effects of prostaglandin (PG) E2 and D2 on the plasma levels of arginine-vasopressin (AVP) and oxytocin (OXT) in rabbits, and on the release of the both hormones from the isolated posterior pituitary of rats were examined. An intraventricular administration of PGE2 to a rabbit raised the plasma levels of the both hormones. An intraventricular injection of PGD2 also increased the plasma level of OXT but not that of AVP. The release of AVP and OXT from fragments of the posterior pituitary of a rat was not influenced by perfusion with Eagle MEM medium containing 10(-6) or 10(-5) M PGE2 and D2.     

Effects of lipopolysaccharide on interleukin-2-induced cytotoxic activity of murine splenocyte cultures: role of prostaglandin E2 and interferons

Summary Splenocytes cultured for 24 h in the presence of interleukin-2 (IL-2), lipopolysaccharide (LPS) or both together expressed a cytotoxic acitvity against the YAC-1 lymphoma cell line and to a lesser extent against P815 mastocytoma cells. The association of IL-2 and LPS had an additive effect on induction of cytotoxicity. The IL-2-induced cytotoxic activity lasted for the whole of the culture; however, the addition of LPS at the initiation of the culture increased the cytotoxic activity during its the early phase, the increment being followed by a fall of lytic activity after 72 h of culture. Assessment of interferon (IFN) in the culture supernatants showed (a) a production of IFN by IL-2-supplemented cultures, (b) a more potent IFN production by cultures treated with IL-2 plus LPS (including 20% IFN/), (c) and that indomethacin (1µm) potentiated the effect of either IL-2 or LPS used alone but did not significantly increase the cytotoxic activity of cultures treated with IL-2 plus LPS (the one that produced a high level of IFN). When cultures were treated by an anti-IFN antibody we observed no change in the cytotoxic activity; however, in the presence of anti-IFN/ serum the cytotoxic activity of cultures treated with IL-2 plus LPS was inhibited after 24 h but stimulated after 72 h. When cultures treated with IL-2 plus LPS were supplemented with both indomethacin and anti-IFN/ the cytotoxic activity assessed after 72 h of culture was maintained at the same level as that of IL-2-treated cultures, hence the fall after 72 h of the cytotoxicity of cultures initiated in the presence of LPS alone was affected by both the immune serum and the cyclooxygenase inhibitor. Altogether these data show that when splenocytes are cultured for more than 72 h in the presence of IL-2 and LPS their cytotoxic activity decreases, and it is likely that this diminution is linked to the endogenous prodution of prostaglandin E₂ and IFN/.     

Effects of hyperthermia on fetal and maternal plasma prostaglandin concentrations and uterine activity in sheep

The exposure of pregnant sheep to high ambient temperatures (43 degrees C) for 8 hours, sufficient to significantly elevate maternal and fetal body temperature +2.0 degrees C (p less than 0.001) and +1.9 degrees C (p less than 0.001) respectively, resulted in significant increases in PGE2 plasma concentrations in both the maternal and fetal circulations. Plasma PGF2 alpha concentrations were significantly raised in the fetal circulation but not the maternal during hyperthermia. The increase in prostaglandin concentrations were correlated with the magnitude of the increase in maternal and fetal body temperature. Uterine activity also increased during hyperthermia, probably as a result of the increase in prostaglandin concentrations. We propose that increased synthesis and release of prostaglandins from the uterus and/or placenta is an adaptive response to hyperthermia, and may protect the fetus from the consequences of heat stress.     

Effects of prostaglandin E2 and lipopolysaccharide on osteoclastogenesis in RAW 264.7 cells

INTRODUCTION: Prostaglandins (PGs) can act on both hematopoietic and osteoblastic lineages to enhance osteoclast formation. METHODS: We examined PGE2 stimulated osteoclastogenesis in RAW 264.7 cells and the role of endogenous PGE2 in lipopolysaccharide (LPS) stimulated osteoclastogenesis. RESULTS: RANKL (1-100 ng/ml) increased formation of osteoclasts, defined as tartrate resistant acid phosphatase multinucleated cells, with peak effects at 30 ng/ml. Addition of PGE2 (0.01-1.0 microM) to RANKL (30 ng/ml) dose dependently increased osteoclast number 30-150%. Use of NS-398 (0.1 microM) or indomethacin (Indo, 1.0 micro M) to block endogenous PG synthesis had little effect on the response to RANKL alone but significantly decreased the response to PGE2. Addition of LPS (100 ng/ml) to RANKL increased osteoclast number 50%, and this response was significantly decreased by NS-398 and Indo. RANKL and PGE2 produced small, additive increases in COX-2 mRNA levels, while LPS produced a larger increase. PG release into the medium was not increased by RANKL and PGE2 but markedly increased by LPS. CONCLUSION: We conclude that RANKL stimulated osteoclastogenesis can be enhanced by PGE2 and LPS though direct effects on the hematopoietic cell lineage and that these effects may be mediated in part by induction of COX-2 and enhanced intracellular PG production.     

Soluble interleukin-2 receptors in ulcerative colitis

T-Cell activation results in the release or shedding of a soluble form (45 kDa) of the cellular (55 kDa) low-affinity interleukin-2 receptor (alpha-chain) (slL-2R). The present study was performed to investigate if the serum concentration of sIL-2R is a marker of disease activity in patients with ulcerative colitis (UC), a chronic inflammatory bowel disease. Twenty-seven UC patients (about half of them in remission) and 13 healthy volunteers were studied, sIL-2R concentrations were measured by an enzyme-linked immunosorbent assay, and significantly elevated median sIL-2R values were found in clinically active UC (150 pg/ml; range 100-420), compared to inactive UC (145 pg/ml; range 110-255), and healthy controls (110 pg/ml; range 80-165) (p < 0.01). There was no correlation between sIL-2R concentrations and extent of the disease. Due to the overlap of serum sIL-2R concentrations between different disease stages and controls, the general diagnostic value seems to be limited. However, since slL-2R release is an IL-2 dependent phenomenon, we conclude that the demonstration of increased serum sIL-2R concentrations in UC suggests the existence of an enhanced T-cell activation in vivo in this disease. Further longitudinal studies are required to elucidate if repeated measurements of sIL-2R levels provide an additional way of monitoring UC disease activity in individual patients.