Immunoregulatory action of melatonin. The mechanism of action and the effect on inflammatory cells

Literature data indicate a significant immunoregulatory role of melatonin. Melatonin exerts an effect directly affecting leucocytes bearing specific melatonin receptors or indirectly by means of melatonin regulating other hormones, opioids or cytokines. Despite numerous experiments, the influence of the hormone on the immune system is still controversial. Melatonin affects the immune response acting as both an activator and an inhibitor of the inflammatory process. The hormone acts as an "immunological buffer" activating impaired immunity in immunosuppression, chronic stress or old age as well as suppressing overreaction of the immune system. Melatonin mediates between neurohormonal and immune systems by means of the immune-pineal axis acting as a negative feedback mechanism. The axis connects development of the immune reaction with pineal activity and melatonin secretion induced by inflammatory mediators. The seasonal and circadian fluctuation of the melatonin level and the fluctuation related changes of the immune parameters can be responsible for some autoimmune and infectious diseases. In spite of that, there is a growing number of papers suggesting considerable therapeutic potential of melatonin in inflammatory disease treatment. This paper presents well-systematized information on the mechanism of melatonin action and its influence on cells involved in the inflammatory process - neutrophils and monocytes.

Does the Selenium (SE) Level and Se-Dependent Enzyme Activity in Blood Plasma Correlate with Human Lymphocyte Subpopulations and Function?

Recent literature data on the effects of Se on subpopulations of T lymphocytes, on autologous mixed lymphocyte reaction (AMLR) and on natural killer (NK) cell cytotoxicity are limited or poorly defined. In healthy volunteers we have estimated se levels, glutathione peroxidase (GSH-Px) activity and lipid peroxide levels in human plasma and simultaneously, the subpopulations of T lymphocytes, proliferation in AMLR, and activity of NK cells.

We found a significantly positive correlation between the selenium level and GSH-Px activity. The proliferative response in AMLR significantly correlated with plasma selenium levels but not with GSH-Px activity. NK cytotoxicity, subpopulations of T lymphocytes, and lipid peroxide levels did not correlate with both selenium concentration and GSH-Px activity. We suppose that the effect of Se on the proliferation of suppressor T lymphocytes (Ts) in AMLR is not mediated through GSH-Px activity and fluctuations of Se concentration within a physiological range in healthy persons do not affect NK cytotoxicity.

[Chosen anthropometric parameters and concentrations of leptin and adiponectin in extreme obese patients treated with implantation of a gastric balloon]

Fatty tissue derived adipocytokines regulate appetite, but in abnormal concentration impair systemic metabolic homeostasis and make the patients prone to inflammatory related disorders. The aim of study was to examine whether weight loss in patients after implementation of a gastric balloon is reflected in changes in chosen anthropometrical parameters and in the concentration of leptin and adiponectin in serum.

MATERIALS AND METHODS

The study group consisted of 18 extreme obese patients (BMI>39.9, mean age 39.5±12.1 years, 12 men, 6 women), undergoing implementation of a gastric balloon for 6 months. The control group consisted of 18 healthy volunteers. The adiponectin and leptin concentrations in the sera and the calculated % body fat and indicators: BMI, WHR, VAI, BAI, WHtR were determined prior to implementation and after the balloon removal and then further parameters were calculated: % excessive weight loss, % weight loss.

RESULTS AND CONCLUSIONS

All the parameters and leptin concentration in the tested group were markedly upregulated and adiponectin concentration was significantly lower compared to controls. Reduction in the body mass in patients subjected to BIB, reflected in leptin and anthropometrical parameters down-regulation, (except WHR and VAI), was accompanied with normalization of adiponectin concentration that affect metabolism and is important regulator of hunger and satiety.

CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF SOME MEDICINAL PLANTS FROM LAMIACEAE FAMILY

Chemical composition and antibacterial activity of aqueous (ethanolic and methanolic) extracts from herbs often used in Polish cuisine and traditional herbal medicine including thyme (Thymus vulgaris L.), rosemary (Rosmarinus officinalis L.), oregano (Origanum vulgare L.), peppermint (Mentha piperita L.) and sage (Salvia officinalis L.) were compared. The aqueous ethanolic extracts contained slightly higher levels of phenolics compared to the aqueous methanolic extracts. In turn, GC-MS analysis showed that the aqueous methanolic extracts of thyme, rosemary and sage contained several additional compounds such as eugenol or ledol. The present studies also indicated that the bacterial species applied in the experiment exhibited different sensitivities towards tested extracts. Staphylococcus aureus strains were found to be the most sensitive bacteria to aqueous (ethanolic and methanolic) rosemary and sage extracts and aqueous methanolic thyme extract. Klebsiella pneumoniae ATCC 13883 and Proteus vulgaris NCTC 4635 were more susceptible to the aqueous methanolic thyme extract. However, Listeria monocytogenes 1043S was the most sensitive to the aqueous ethanolic rosemary extract. Gram-positive bacteria were generally more sensitive to the tested extracts than Gram-negative ones.

Evaluation of the efficiency of different disruption methods on yeast cell wall preparation for β-glucan isolation

Selected methods for yeast cell disruption were evaluated to establish their suitability for cell wall preparation in the process of β-glucan isolation. The effect of different disruption methods on contents of total saccharides, β-glucans and proteins in the produced cell walls preparations was analyzed. The degree of cell wall purification from intracellular components was established on the basis of the ratio of solubilised material. The investigated methods included: cell exposure to hot water (autoclaving), thermally-induced autolysis, homogenization in a bead mill, sonication and their combinations. Experimental systems were prepared in water (pH 5.0 and pH 7.0) and Tris-HCl buffer (pH 8.0). The Saccharomyces cerevisiae yeast cell wall preparations with the highest degree of cytosol component release and purification of β-glucans were produced by 30 min of cell homogenization with zirconium-glass beads (0.5 mm in diameter). This was confirmed by the highest ratio of solubilised material (approx. 64%–67%). The thus-produced preparations contained ca. 60% of total saccharides, 13%–14% of β(1,3)/(1,6)-glucans, and approx. 35% of crude proteins. Similar results were obtained after autolysis coupled with bead milling as well as with sonication, but the time required for these processes was more than 24 h. Homogenization in a bead mill could be valuable for general isolation procedures because allows one to eliminate the different autolytic activity of various yeast strains.

Regioselective hydrolysis of acetates in the presence of different yeast strains

The model compound, hexane-1,2-diol diacetate, was hydrolyzed in the presence of supernatant obtained after cultivation of 4 yeast strains: Pichia jadinii, Rhodotorula glutinis and Yarrowia lipolytica KKP 379 and Saccharomyces cerevisiae 102 to evaluate the type of catalysis. The regioselectivity of extracellular enzymes as a function of hydrolysis towards primary and secondary acetic acid ester groups was monitored. The enzymes secreted by P. jadinii, R. glutinis and Y. lipolytica KKP 379 exhibited high regioselectivity towards primary position, while those from S. cerevisiae showed practically no discrimination between the ester groups.

The influence of uremic high cystatin C concentration on neutrophil apoptosis and selected neutrophil functions isolated from healthy subjects

Background

Cystatin C (cC) is a cysteine protease inhibitor that may influence immune response. Our aim was to test the effect of a high concentration of cC, characteristic for uremic patients, on neutrophil (PMN) apoptosis and respiratory burst, as well as the cC secretion from PMNs stimulated with proinflammatory cytokines.

Material/Methods

PMNs from 35 healthy volunteers aged 27–61 years were cultured in presence of cC, IL-1β or TNF-α. The percentage of apoptotic cells based on DNA depletion, Fas, FasL and caspase -3 expression were assessed. CC concentrations were determined by ELISA test. The influence of cC on spontaneous, fMLP-, PMA- or OZ-induced burst response of PMNs was tested using chemiluminescence.

Results

PMN cultured in the presence of cC resulted in a significant drop in apoptotic cell percentage (38% [11%; 65%]) compared both to control (70% [29%; 92%], and to the cells cultured with TNF-α (58% [24%; 85%]). These differences were not accompanied by Fas, FasL and caspase-3 expression changes. Spontaneous, fMLP- and PMA-stimulated oxidative burst of PMNs preincubated with cC were significantly downregulated. IL-1β markedly diminished and TNF-α significantly increased cC concentration in culture supernatants.

Conclusions

The presented results suggest that antiapoptotic activity of cC results from its inhibitory effect on ROS production. Thus, the higher concentration of cC characteristic for uremic patients may modulate acute inflammation through maintaining PMN longevity and inhibiting their respiratory burst and proinflammatory cytokine-related changes in cC release from PMNs.

The effect of uremia and hemodialysis on caspase-1 and caspase-3 activity in neutrophils

BACKGROUND

Neutrophils in uremia maintain chronic inflammation, which contributes to malnutrition and immunity disorders. The influence of hemodialysis on the life span of neutrophils is unclear, although many authors postulate its apoptotic effect. Erythropoietin (EPO) is an antiapoptotic factor for various cells. We investigated factors possibly interfering in apoptosis of neutrophils in hemodialysis (HD) patients, such as HD session, parathormone (PTH), dose of EPO, inflammation and nutrition.

SUBJECTS AND METHODS

Twenty HD patients and ten healthy controls were donors of neutrophils. We evaluated caspase-1 and caspase-3 activities, related to apoptosis of neutrophils, before and after a 4-hour HD session with cuprophane or polysulphone dialyzer. We measured serum concentrations of C-reactive protein, cholesterol, albumin, prealbumin and transferrin. Time of dialysis treatment, PTH level and dose of EPO were also evaluated.

RESULTS

We observed a significant increase in caspase-1 activity and decrease in caspase-3 activity in neutrophils after HD with cuprophane, but not with polysulphone. Caspase-1 activity correlated positively with EPO dose and negatively with PTH level. Caspase-3 correlated negatively with the time of dialysis treatment. No correlation between caspase activity and markers of inflammation or nutrition was noticed.

CONCLUSIONS

The results suggest that HD with bioincompatible cuprophane may prolong the life span of neutrophils due to the intense inflammatory reaction and high activity of caspase-1. Time of dialysis treatment, PTH level and EPO dose potentially influence the life span of neutrophils. PTH seems to have a proapoptotic effect of neutrophils, while EPO is an antiapoptotic factor.

[Cystatin C--modulator of immune processes]

Cystatin C is a lowmolecular protein (13 kDa) that inhibits the activity of lysosomal cysteine proteinases with the strongest activity against cathepsin B and H. The recent experiments show that the level of cystatin C is independented of chronic and acute inflammatory process which frequently coexist with end stage renal diseases. Recent studies challange the theory because a higher concentration of cystatin C in serum correlated well with a higher concentration of inflammatory markers such as a CRP and fibrinogen in the patients. In vitro experiments on cultured monocytes and macrophages discovered that after stimulation by LPS and INF the expression of the cystatin C gene and synthesis of this protein was reduced. Cystatin C plays important modulatory function in regulation of the natural immunity, protecting our body against viruses, bacteries and parasites. Moreover, cystatin C binds the C4 component and modulates activation of the classical complement pathway. The experiments also show that cystatin C could influence non-specific immune response through the inhibition of the superoxide anion generation (respiratory burst), phagocytosis, chemotaxis and apoptosis of neutrophils. Similarly, the cystatin C can modulate the specific immune response through the inhibition of cathepsin S, bindining membrane receptors for TGF-beta or increasing MHC class II expression on dendritic cells.

Mevalonate pathway modulation is associated with hepatitis C virus RNA presence in peripheral blood mononuclear cells

Peripheral blood mononuclear cells (PBMC) constitute the main extrahepatic reservoir of hepatitis C virus (HCV). Lipid metabolism of host seems to play important role in HCV infection. The relationship between HCV presence in PBMC and the expression of mevalonate pathway has not been elucidated. The aim of this study was to investigate the association between mevalonate pathway and HCV RNA presence in PBMC after anti-HCV treatment. 67 serum and corresponding PBMC samples were collected from patients at the end of interferon alpha and ribavirin treatment. Serum total cholesterol, HDL-C and LDL-C fractions, triglycerides, as well as intracellular cholesterol and expression level of HMG-CoA reductase, geranylgeranyl pyrophosphate synthase in PBMC were measured and matched for the HCV RNA presence or absence in sera/PBMC. HCV RNA elimination from sera and PBMC was associated with higher serum cholesterol (118.5mg/dL) and LDL-C (66.42mg/dL) levels, compared to the group, where HCV RNA was detected only in PBMC (100.94 and 53.22mg/dL) or the group, where HCV RNA was found in both sera and PBMC (86.79 and 43.79mg/dL) after treatment. Increased expression of geranylgeranyl pyrophosphate synthase was found in the majority of PBMC samples that harbored HCV RNA after elimination of HCV RNA from sera. The expression of mevalonate pathway after antiviral treatment seems to be modulated depending on HCV RNA status in peripheral blood mononuclear cells.

Effect of luteinizing hormone-releasing hormone (LHRH) analogue treatment on a cytokine profile in prostate cancer patients

The aim of the study was to test serum concentrations of the chosen cytokines in patients with prostate cancer (PCa) treated with an luteinizing hormone-releasing hormone (LHRH) analogue. We tested interleukin (IL)-2, IL-10, tumor necrosis factor (TNF)-alpha, interferon (INF)-gamma in blood at three time points; I - before the injection, II - 10 days and III - 20 days after the injection in 14 men with PCa. Patients had one depot injection of the LHRH analogue monthly. The cytokine concentrations in serum samples were determined by ELISA method. Prostate specific antigen (PSA) level was examined before and after six months of the LHRH analogue treatment. After six months of the therapy, we observed normalization of serum PSA value from 16.48 ng/ml to 1.45 ng/ml. LHRH analogue injection resulted in a significant drop of the IL-2 concentration, and the value gradually returned to normal in the next 20 days. IL-10 concentration transiently increased and then was down-regulated. Serum TNF-alpha and INF-gamma concentrations in PCa patients were significantly lower compared to controls and were not affected by the treatment. LHRH analogue treatment in PCa patients modulates concentrations of the chosen cytokines which may result both in antitumor and a transient immunosuppressive effect.

Increased levels of soluble TNF-alpha receptors and cellular adhesion molecules in patients undergoing bioincompatible hemodialysis

BACKGROUND

The study aimed to differentiate the effects of hemodialysis (HD) and chronic renal failure (CRF) on the levels of circulating tumor necrosis factor-alpha (TNF-alpha) and TNF-alpha receptors p55 and p75, soluble vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1), soluble endothelial-leukocyte adhesion molecule-1 (sE-selectin) and sP-selectin in 18 patients on regular HD treatment with cuprophane membrane in relation to 15 non-dialyzed CRF patients and 15 healthy controls.

METHODS

The serum concentrations were determined with standard ELISA assays.

RESULTS

Blood serum p75 and p55 were approximately tenfold increased in CRF (36.7 +/- 6.2 and 27.1 +/- 5.6 ng/ml) and HD patients (45.6 +/- 18.4 and 28.7 +/- 5.9 ng/ml) before the HD session (HD 0), during (HD 20) the session (45.7 +/- 18.4 and 28.5 +/- 7.3 ng/ml) and after (HD 240) the HD session (52.1 +/- 17.4 and 30.9 +/- 8.2 ng/ml) in comparison to control values (5.6 +/- 1.3 and 2.4 +/- 0.8 ng/ml, respectively) (p < 0.01). The highest increment of p75 at the end of HD session (HD 240) was also significantly higher than at preceding time points (HD 0 and 20) (p < 0.05). However, the remaining study parameters did not change during an HD session. Also, there were no relevant changes in TNF-alpha levels if (HD 0) 22.7 +/- 21.5 ng/ml and (HD 240) 21.1 +/- 18.9 ng/ml were compared. Chronic HD status was related to the increase of sVCAM-1 and sICAM-1 levels. Prior to HD, T0 sVCAM-1 and sICAM-1 concentrations were 2,180.4 +/- 761.8 and 567.3 +/- 218.8 ng/ml, during HD (T20): 2,172.7 +/- 759.2 and 602.3 +/- 379.9 ng/ml, and after HD (T240): 2,401.6 +/- 756.4 and 648.3 +/- 183.5 ng/ml, respectively (p < 0.05 vs. controls and CRF patients). sVCAM-1 and sICAM-1 serum levels (1,262.2 +/- 472.9 and 165.6 +/- 50.4 ng/ml) were similar in CRF patients and healthy controls (854.4 +/- 241.5 and 217.6 +/- 74.2 ng/ml, respectively). Even though serum sE- and sP-selectin in CRF patients did not differ from the control (39.8 +/- 21.3 vs. 42.1 +/- 18.9 ng/ml and 187.9 +/- 66.9 vs. 198.8 +/- 62.2 ng/ml, respectively), their levels were increased in HD patients up to 111.9 +/- 54.6 and 453.2 +/- 231.1 ng/ml in patients prior to HD, 118.7 +/- 66.2 and 350.8 +/- 114.8 ng/ml during the HD session and then 132.3 +/- 61.1 and 368.3 +/- 126.6 ng/ml, respectively, after its completion (p < 0.05 in comparison with CRF patients and controls).

CONCLUSIONS

The increased circulating TNF-alpha receptors appear more associated with the uremic milieu than HD-related systemic inflammation, whereas increased soluble cellular adhesion molecules in patients undergoing bioincompatible HD may be related to the enhanced systemic inflammation specifically due to maintenance HD.

Quantitative analysis of cyclin E and protein p34 cdc2 expression in superficial bladder cancer

In the present study, the expression of cyclin E and kinase p34 cdc2 was investigated in preinvasive bladder tumors. The study material consisted of bladder sections (grades: GI--16 cases, GII--10, and GIII--12) collected from 38 patients in the course of the tumor electroresection. Immunohistochemical examinations were carried out with immunoperoxidase method. Antigens were labeled with NCL-CYCLIN E or NCL-p34 cdc2 monoclonal antibodies (Novocastra, UK). Positive reaction was demonstrated using ABC-universal Kit (Novocastra, UK). Differences in the protein expression in relation to the tumor grade were determined with a non-parametric Mann-Whitney's test. Increasing grade of tumors was associated with down regulation of cyclin E visible as lower percentage of cyclin E-positive cells. These changes were statistically significant for GI group as compared to groups GII and GIII (p<0.001). There were no differences between the study groups in the p34 protein expression. Cyclin E expression was inversely correlated with tumor grade therefore may be helpful in establishing therapeutic procedure.

Flow cytometric evaluation of human neutrophil apoptosis during nitric oxide generation in vitro: the role of exogenous antioxidants

Among numerous inflammatory mediators a nitric oxide molecule is supposed to be important in the modulation of neutrophil survival in vivo and in vitro. The effect of exogenous supply of NO donors such as SNP, SIN-1, and GEA-3162 on the course of human neutrophil apoptosis and the role of extracellular antioxidants in this process was investigated. Isolated from peripheral blood, neutrophils were cultured in the presence or absence of NO donor compounds and antioxidants for 8, 12, and 20 hours. Apoptosis of neutrophils was determined in vitro by flow cytometric analysis of cellular DNA content and Annexin V protein binding to the cell surface. Exposure of human neutrophils to GEA-3162 and SIN-1 significantly accelerates and enhances their apoptosis in vitro in a time-dependent fashion. In the presence of SNP, intensification of apoptosis has not been revealed until 12 hours after the culture. The inhibition of GEA-3162- and SIN-1-mediated neutrophil apoptosis by superoxide dismutase (SOD) but not by catalase (CAT) was observed. Our results show that SOD and CAT can protect neutrophils against NO-donors-induced apoptosis and suggest that the interaction of NO and oxygen metabolites signals may determine the destructive or protective role of NO donor compounds during apoptotic neutrophil death.

Effects of uraemia and haemodialysis on neutrophil apoptosis and expression of apoptosis-related proteins

BACKGROUND

In haemodialysis (HD) patients, it is unclear whether increased apoptosis of neutrophils is due to uraemia or HD itself. The purpose of the current study was to assess the effect of uraemia and HD on the rate of apoptosis and apoptosis-related protein expression in whole blood neutrophils.

METHODS

We employed a whole-blood micromethod to test spontaneous apoptosis and expression of apoptosis-regulating proteins in cultured neutrophils from uraemic patients (pre-HD), HD patients and healthy controls. Blood samples were drawn before, after 20 min and after 4 h of haemodialysis, and were then cultured for 20 h. We evaluated the rate of apoptosis from annexin V and propidium iodide staining, and examined bcl-2, Fas/Apo-1 and p53 expression in the cultured neutrophils.

RESULTS

Fas/APO-1 expression and total percentage of apoptotic whole blood neutrophils of pre-HD and HD patients before HD were significantly higher than controls. There was a transient but significant decrease in the percentage of apoptotic neutrophils and Fas/APO-1 expression after 20 min of dialysis. The expression of bcl-2 protein was significantly lower from neutrophils in HD patients compared with controls, and HD significantly downregulated bcl-2 expression. The p53 protein content in HD patients before HD was significantly higher than in pre-HD patients.

CONCLUSIONS

These findings suggest that uraemia accelerates neutrophil apoptosis by increasing Fas/Apo-1, and that HD does not affect neutrophil apoptosis more than uraemia. In addition, HD produces only in a transient sequestration of potentially apoptotic neutrophils.

Effect of exogenous opioid peptides on TNF-alpha-induced human neutrophil apoptosis in vitro

Polymorphonuclear leukocyte (neutrophil) apoptosis is an important mechanism regulating the life span and some functions of neutrophils at inflamed sites. Opioid peptides are present in the peripheral circulation and their concentrations rapidly increase as a result of stress and inflammation. The effect of opioid peptides such as met-enkephalin (M-ENK) and beta-endorphin (beta-END) on tumor necrosis factor (TNF)-alpha-induced apoptosis in human neutrophils in vitro was investigated. Neutrophils isolated from peripheral blood were cultured in the absence or presence of 10(-6)-10(-10) M of opioid peptides for 8, 12 and 18 h. Features of apoptotic neutrophils were measured by a flow cytometric method based on analysis of the apoptotic nuclei (DNA content). We found that M-ENK and beta-END enhanced both uninduced and TNF-alpha-induced neutrophil apoptosis in vitro in a dose-dependent manner. The effect of opioid peptides on the modulation of neutrophil apoptosis was not reversed by the opioid-receptor antagonist naloxone. The results suggest that M-ENK and beta-END can regulate neutrophil life span via apoptosis and in this way may participate in the resolution of inflammation.