Cytotoxic actions of cytokines on cultured mouse luteal cells are independent of nitric oxide

Preliminary Studies of the Immunomodulator Effect of the Bougainvillea xbuttiana Extract in a Mouse Model

Bougainvillea xbuttiana is used as an analgesic in folk medicine in Mexico. The purpose of the present study was to determine the effects of the ethanolic extract from B. xbuttiana on macrophages activities. The phytochemical screening was performed for determine the presence of alkaloids, flavonoids, triterpenes, and saponins. The effects of B. xbuttiana were analyzed using the macrophages activities as determined by the H₂O₂ release, spreading and phagocytic index, vacuoles formation percentage, and mediators production. The viability percentage was determined in live cells after fixing and staining with crystal violet. The presence of H₂O₂ in macrophages was performed by using the peroxidase-phenol red solution. The cytokine production was determined by two assays, ELISA for detection of IL-6, IL-10, and IFN-γ and biological assay for TNF detection. The results showed that the Bxb extract dose-dependent manner produces (a) an increase in levels of H₂O₂ and spreading and vacuoles formation percentages, (b) a decrease in phagocytic index and in the amounts of TNF, IL-6, and IFN-γ, and (c) an increase significant in IL-10 and NO production. This study indicates that the ethanolic extract from Bougainvillea xbuttiana was able to activate macrophages. The combination of these results suggests that this extract has an immunomodulator effect.

The interface of the immune and reproductive systems in the ovary: lessons learned from the corpus luteum of domestic animal models

The dynamic changes that characterize the female reproductive system are regulated by hormones. However, local cell-to-cell interactions may mediate responsiveness of tissues to hormonal signals. The corpus luteum (CL) is an excellent model for understanding how immune cells are recruited into tissues and the role played by those cells in regulating tissue homeostasis or demise. Leukocytes are recruited into the CL throughout its lifespan, and leukocyte-derived cytokines have been found in corpora lutea of all species examined. The proinflammatory cytokines inhibit gonadotropin-stimulated steroidogenesis, profoundly stimulate prostaglandin synthesis by luteal cells, and promote apoptosis. However, there is mounting evidence that leukocytes and luteal cells communicate in different ways to maintain homeostasis within the functional CL. Domestic animals have provided important information regarding the presence and role of immune cells in the CL.

Regulation of HAS expression in human synovial lining cells of TMJ by IL-1beta

Hyaluronan (HA), a major glycosaminoglycan of synovial fluid, is synthesised by a class of membrane-bound HA synthase (HAS) proteins. In the present study, we investigated the regulatory roles of IL-1beta on HAS gene expression and HA production by the fibroblastic synovial lining cells. The synovial lining cells from synovial membrane in human temporomandibular joint (TMJ) were cultured and characterised using immunocytochemistry with CD14, CD44, and vimentin monoclonal antibodies. With or without treatment with IL-1beta, the production of HA was detected with radiometric assay and the expression of HAS mRNAs were analysed with a semi-quantitative reverse transcribed polymerase chain reaction (RT-PCR). HA synthesis was significantly augmented with 1ng/ml of IL-1beta for both 24 and 48h stimulation, however the production of HA declined if stimulated with 10ng/ml of IL-1beta. The expression of HAS2 and 3 mRNA were enhanced about 4.2- and 7.2-fold after 4h stimulation with 1ng/ml of IL-1beta, respectively. From these results, it is concluded that IL-1beta functions on regulating HAS expression and consequently promoting the secretion of HA in synovial lining cells from TMJ.

Toxin gamma from Tityus serrulatus scorpion venom plays an essential role in immunomodulation of macrophages

Fraction number II obtained from Sephadex G-50 gel filtration of the soluble venom from the Brazilian scorpion Tityus serrulatus (TSV) stimulates macrophage function in vitro. The aim of this study was to identify which one of the several components of this fraction was responsible for the main stimulatory activity on macrophages. This component was identified as sub-fraction II-11, also known by the name of gamma toxin or simply abbreviated Ts1, which stands for toxin 1 of T. serrulatus venom. The effect of Ts1 was analyzed by detection of inflammatory mediators. Several functional bioassays were performed: TNF activity was assayed by measuring its cytotoxicity on L929 cells, whereas IL-1, IL-6, IFN-gamma and IL-10 were assayed by enzyme-linked immunosorbent assay. The levels of NO were evaluated by Griess colorimetric reactions in supernatants of macrophages in culture exposed to Ts1 and compared with FII. Macrophages exposed to Ts1 increase the production of mediators. With respect to the pro-inflammatory cytokines, an increment of IL-1alpha, IL-1beta was observed after 12 h; the maximum levels of IL-6 and TNF were observed after 24 h; the highest levels of IFN-gamma and NO were observed after 72 h. In contrast, the highest levels of anti-inflammatory cytokines such as IL-10 were observed after 120 h. With respect to the balance of pro- and anti-inflammatory cytokines, IL-1alpha/IL-10 and IL-6/IL-10 ratios appear incremented between 12 and 48 h in macrophages exposed to Ts1. IL-1beta/IL-10 and TNF/IL-10 ratios were increased in macrophages exposed to Ts1 for 12 h. IFN-gamma/IL-10 ratios increased up to 48 h, decaying thereafter. Elevated IL-6/TNF ratios were observed up to 24 h. These ratios may possibly reflect the inflammatory status during exposition to the venom. In conclusion, these data indicate that Ts1 has an important immunomodulatory effect on macrophages, and add important knowledge for understanding scorpion envenomation. It also opens the field for further research about the intoxication phenomenon as it is discussed here.

Balance between pro- and anti-inflammatory cytokines in mice treated with Centruroides noxius scorpion venom

CSV consists of a very complex of molecules and demonstrates significant cellular activities capable of stimulating immune functions in vivo. The purpose of this study was to analyze the effects of CSV on sex, weight, route of injection and the balance of pro- and anti-inflammatory cytokines in mice. The susceptibility and route of injection were analyzed by lethal (LD(50)) determination. The effects of CSV were also analyzed in blood from immunized mice using detection by means of antibodies and mediators production. Several functional bioassays were employed: TNF activity was assayed by measuring its cytotoxic activity in L929 cells, and other cytokines were assayed by enzyme-linked immunosorbent assay, whereas nitric oxide levels were detected by Griess colorimetric reactions in sera from BALB/c mice. After injecting subcutaneously, the LD(50) presented an increase of the CSV correlation and similar levels of susceptibility were obtained for female and male from BALB/c mice. Significant differences were observed in the time-course of cytokine levels. The balance of pro- and anti-inflammatory cytokines TNF/IL-10 and IL-6/IL-10 ratios were significantly higher in injected mice group when compared with those obtained for non-injected group. The CSV is poor in antigenic composition and it is difficult to get antibodies specific to neutralizing the lethal factor. The effect of immunization with 0.5 LD(50) of CSV on the balance of pro- and anti-inflammatory cytokines was measured. The maximum levels of TNF and IL-6, IFN-gamma and NO were observed on days 7 and 21 after immunization, respectively. IL-10 levels peaked between days 21 and 28 after immunization with CSV. With respect, to balance of pro- and anti-inflammatory cytokines it was possible to observe that negative correlation between serum levels of IL-6/IL-10 and TNF/IL-10 exists. These ratios may possibly reflect the balance of pro- and anti-inflammatory cytokines in serum, which may by manifested in the inflammatory status during the envenoming processes. In conclusion, an increase in the serum levels of TNF and IL-6 may be a useful marker for scorpion envenomation.

Mendonça R, L. Petricevich V. Crotalus durissus terrificus venom interferes with morphological, functional, and biochemical changes in murine macrophage

Crotalus durissus terrificus venom (Cdt) is toxic for a variety of eukaryotic cells, especially at high concentrations. However its effects on host immune cells are not well known. The purpose of this study was to determine the effect of Cdt on functional status and the mediators production in peritoneal macrophages. The effects of Cdt were analyzed in vitro and were detected using functional status of macrophages as determined by the H₂O₂ release, spreading percentage, phagocytic index, vacuole formation, and mediators production. Several functional bioassays were employed: cytotoxicity was determined by taking the lyses percentage and the presence of hydrogen peroxide (H₂O₂) in macrophages, using the horseradish peroxidase-dependent oxidation of phenol red and nitric oxide (NO) in the supernatants of macrophages by the Griess reaction. The tumor necrosis factor (TNF) activity was detected by measuring its cytotoxic activity on L929 cells, and the production the level of other cytokines was assayed using enzyme-linked immunosorbent assay. In vitro studies revealed that Cdt produced (a) a discrete increase in the release of H₂O₂ and vacuole formation; (b) a decrease in spreading percentage and in the phagocytic index; and (c) an increment in the mediators production. More pronounced increments of IL-6 and TNF were observed after 24 and 48 hours, respectively. Maximum levels of IFN-γ and NO were observed after 96 hours. Interestingly, levels of all mediators presented a discreet decrease, as the amount of Cdt was increased. In contrast, the IL-10 levels observed for all doses studied here did not alter. The IL-6/IL-10 ratio may possibly reflect the balance of pro- and anti-inflammatory cytokines in macrophages, which may be manifested in the inflammatory status during the envenoming processes. Taken together, these data indicate that Cdt have a differential effect on macrophage activation and that this venom is a potent inhibitor of anti-inflammatory response.

Indoleamine 2,3-Dioxygenase Participates in the Interferon-gamma-Induced Cell Death Process in Cultured Bovine Luteal Cells1

Interferon-gamma (IFNG) induces apoptotic cell death in bovine luteal cells, but the pathway(s) involved in this process are not well defined. Evidence supporting the involvement of an IFNG-inducible enzymatic pathway that degrades tryptophan in IFNG-induced death of bovine luteal cells is presented in this study. The IFNG-inducible enzyme indoleamine 2,3-dioxygenase (INDO) catalyzes the first step in a metabolic pathway that degrades tryptophan. In the first experiment, RT-PCR revealed the presence of INDO mRNA in luteal cells treated with IFNG, but not in untreated cells. To determine whether INDO participates in IFNG-induced death of bovine luteal cells, an experiment was performed to test the effect of 1-methyl-D-tryptophan (1-MT), an inhibitor of INDO, on IFNG-induced DNA fragmentation in luteal cells. Single-cell gel electrophoresis and microscopic image analysis revealed that 1-MT inhibited DNA fragmentation induced by IFNG. To determine whether supplementation of cell cultures with additional tryptophan could also protect luteal cells from IFNG-induced DNA fragmentation, luteal cells were cultured in the presence of IFNG, and L-tryptophan was added to cultures to achieve final concentrations that were 5-, 10-, or 25-fold higher than the concentration of L-tryptophan found in nonsupplemented culture medium. Supplementation of IFNG-treated luteal cell cultures with elevated concentrations of tryptophan also prevented IFNG-induced DNA fragmentation. We conclude that INDO participates in IFNG-induced death of bovine luteal cells, through a mechanism that involves degradation of tryptophan, thereby reducing tryptophan concentrations to a point insufficient to meet luteal cells needs.

Immunomodulatory effects of the Tityus serrulatus venom on murine macrophage functions in vitro

Tityus serrulatus scorpion venom (TSV) consists of a very complex mixture of molecules and demonstrates significant immunomodulatory activities capable of stimulating immune functions in vivo. The purpose of this study was to compare the crude TSV with fractionated toxins extracted from this venom in order to determine which toxin(s) presented immunomodulatory effects on peritoneal macrophages. TSV was fractionated using gel filtration chromatography resulting in 5 heterogeneous fractions. The effects of these different fractions were analysed in vitro using detection by means of cytokines, oxygen intermediate metabolites (H2O2), and nitric oxide (NO) in supernatants of peritoneal macrophages. Several functional bioassays were employed: tumor necrosis factor (TNF) activity was assayed by measuring its cytotoxic activity in L929 cells, and other cytokines were assayed by enzyme-linked immunosorbent assay, whereas NO levels were detected by Griess colorimetric reactions in culture supernatant of macrophages exposed to different fractions. In vitro studies revealed that all fractions studied here presented an increment in H2O2, NO , and cytokines levels. The more pronounced increments were observed in macrophage cultures exposed to fraction FII which demonstrated that (a) the highest levels of IL-1alpha, IL-beta, and TNF were observed after 12 hours and that (b) the maximum levels of IFN-gamma and NO were observed after 72 hours. Taken together, these data indicate that fractions have a differential immunomodulating effect on macrophage secretion, and that FII is a potent activator of TNF production of macrophages.

Investigations on the expression of cytokines in the canine corpus luteum in relation to dioestrus

Control of luteal regression in the dog is still poorly understood. Unlike other domestic animal species, luteolysis is not prevented by hysterectomy. Indications that PGF(2alpha) may act as an endogenous luteolytic agent have been found only in pregnant animals during the prepartal decline of progesterone. Evidence from several species indicates that the immune system plays an important role in corpus luteum (Cl) function, possibly by the release of cytokines from immigrant immune cells. Hence, in the present experiment we attempted to examine the expression of cytokines in the canine Cl during the course of dioestrus (formation and regression of the Cl), using RT-PCR. Groups of 4-5 bitches were ovario-hysterectomised on days 5, 15, 25, 35, 45 and 60-80 after ovulation. Canine-specific primers for IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, TNFalpha, IFNgamma and TGFbeta1 were used. Positive and negative controls were included in all tests. Adequate expression was confirmed by sequencing selective samples of positive PCR products. The expression of mRNA for IL-8, IL-10, IL-12, TNF-alpha and TGF-beta1 was detected in all samples at each stage of dioestrus, without any obvious variations indicating a likely modulatory function of these cytokines in differentiation, maintenance or regression of the canine Cl. All tests for the expression of mRNA for IL-4, IL-1beta and IL-2 were negative. More negative than positive results were obtained when testing for the expression of mRNA for IL-6 and IFN-gamma, leading to the conclusion that expression of these two cytokines is at a low level, and no conclusion can be drawn as to their involvement in control of Cl function.

Influence of interleukin-1alpha and COX-2 over the metabolism of arachidonic acid and glucose in isolated uterus of restricted diet rats

Isolated uteri from rats fed with a normal diet convert [14C]arachidonate into eicosanoids: PGE(2), PGF(2alpha), TXB(2) and 6-keto-F(1alpha). Restricted diet (50% of the normal diet, during 25 days) diminishes the levels of PGE(2), PGF(2alpha) and TXB(2). The addition of Interleukin-1alpha to the Krebs-Ringer bicarbonate medium increases sharply the production of eicosanoids. Inhibitors of nitric oxide synthase, Nomega-nitro-L-arginine methyl ester or aminoguanidine, do not prevent eicosanoids increase. Conversely, NS-398 (a selective inhibitor of COX-2) blocks the increase of eicosanoids while PGE(2) blocks eicosanoids production mediated by IL-1alpha. Other experiments with uteri of underfed rats confirm that interleukin-1alpha produces an increase in the glucose metabolism. The addition of Nomega-nitro-L-arginine methyl ester, aminoguadinine or NS-398 blocked such stimulation. It is concluded that Interleukin-1alpha produces an increase of glucose metabolism in uteri isolated from underfed rats by two different mechanisms, both involving COX-2: (1) nitric oxide independent and (2) nitric oxide dependent.

Effect of Tityus serrulatus venom on cytokine production and the activity of murine macrophages

THE purpose of this study was to investigate the effects of Tityus serrulatus venom (TSV) on murine peritoneal macrophages evaluated in terms of activation. The effects of crude TSV were analysed by detection of cytokines, oxygen intermediate metabolites (H2O2) and nitric oxide (NO) in supernatants of peritoneal macrophages. Several functional bioassays were employed including an in vitro model for envenomating: cytotoxicity of TSV was assessed using the lyses percentage. Tumor necrosis factor (TNF) activity was assayed by measuring its cytotoxic activity on L-929 cells, and interleukin-6 (IL-6) and interferon-gamma (IFN-gamma) were assayed by enzyme-linked immunosorbent assay, whereas NO levels were detected by Griess colorimetric reactions in culture supernatant of macrophages incubated with TSV and subsequently exposed to either lipopolysaccharide or IFN-gamma. Incubation of macrophages with TSV increased production of IL-6 and IFN-gamma in a dose-dependent manner. TNF production was not detected in supernatants treated with TSV at any concentration. The increase in IL-6 secretion was not associated with concentration-dependent cytoxicity of TSV on these cells. These data suggest that the cytotoxicity does not appear to be the main cause of an increased cytokine production by these cells. Although NO is an important effector molecule in macrophage microbicidal activity, the inducing potential of the test compounds for its release was found to be very moderate, ranging from 125 to 800 mM. Interestingly, NO levels of peritoneal macrophages were increased after IFN-gamma. Moreover, NO production had an apparent effect on macrophage activity. The results obtained here also shown that the TSV induces an important elevation in H2O2 release. These results combined with NO production suggest that TSV possesses significant immunomodulatory activities capable of stimulating immune functions in vitro.

Role of cytokines and nitric oxide in the induction of tuberculostatic macrophage functions

The aim of this study was to determine phenotypic differences when BCG invades macrophages. Bacilli prepared from the same BCG primary seed, but produced in different culture media, were analysed with respect to the ability to stimulate macrophages and the susceptibility to treatment with cytokines and nitric oxide (NO). Tumour necrosis factor (TNF) activity was assayed by measuring its cytotoxic activity on L-929 cells, interleukin-6 (IL-6) and interferon-gamma (IFN-gamma) were assayed by enzyme-linked immunosorbent assay (ELISA), whereas NO levels were detected by Griess colorimetric reactions in the culture supernatant of macrophages incubated with IFN-gamma, TNF or NO and subsequently exposed to either BCG-I or BCG-S. We found that BCG-I and BCG-S bacilli showed different ability to simulate peritoneal macrophages. Similar levels of IL-6 were detected in stimulated macrophages with lysate from two BCG samples. The highest levels of TNF and IFN-gamma were observed in macrophages treated with BCG-S and BCG-I, respectively. The highest levels of NO were observed in cultures stimulated for 48 h with BCG-S. We also found a different susceptibility of the bacilli to exogenous treatment with IFN-gamma and TNF which were capable of killing 60 and 70% of both bacilli, whereas NO was capable of killing about 98 and 47% of BCG-I and BCG-S, respectively. The amount of bacilli proportionally decreased with IFN-gamma and TNF, suggesting a cytokine-related cytotoxic effect. Moreover, NO also decreased the viable number of bacilli. Interestingly, NO levels of peritoneal macrophages were significantly increased after cytokine treatment. This indicates that the treatment of macrophages with cytokines markedly reduced bacilli number and presented effects on NO production. The results obtained here emphasize the importance of adequate stimulation for guaranteeing efficient killing of bacilli. In this particular case, the IFN-gamma and TNF were involved in the activation of macrophage bactericidal activity.

Antisteroidogenic action of nitric oxide on human corpus luteum in vitro: mechanism of action

To analyze the mechanism by which nitric oxide (NO) exerts its antisteroidogenic action, human luteal cells were cultured during 24 and 48 h with L-arginine (L-Arg, 1 mmol/L); 1,2(2-trifluoromethylphenyl)imidazole (TRIM) (50 micromol/L and 1 mmol/L) and cyclic guanosine monophosphate (cGMP) analog (8-Br-cGMP, 1 mmol/L). Estradiol, nitrite, and P450 AROM activity were determined in culture media. Total cGMP concentration was evaluated in the cells and culture media by radioimmunoassay, and NADPH diaphorase was used as a histochemical marker for NO synthase (NOS) activity. During the corpus luteum (CL) life-span, NO affected estradiol secretion in an age-dependent manner, with an inhibition in mid-CL (37%; p < 0.05) in agreement with our previous results, and no significant modification in early and late CL. Basal nitrite concentration in 24 and 48 h of midluteal cell cultures (42 and 93 pmol/10(6) cells, respectively) was increased by L-Arg (53% and 88%) and inhibited by the two TRIM concentrations; also, an intense diaphorase reactivity was observed in endothelial cells and luteal parenchyma. Total cGMP was not detected in cell cultures and 8-Br-cGMP did not modify estradiol secretion, whereas aromatase activity was strongly inhibited by L-Arg (70%, p < .05). These results suggest that both NOS isoforms are active in midluteal cells, and the mechanism of action for NO on in vitro estradiol secretion may be an inhibition of P450 AROM activity.

Review: cytokine involvement in ovarian processes

PROBLEM

Expression of tumor necrosis factor-alpha (TNF) and interleukins 1 alpha and 1 beta (IL-1) have been reported in ovaries of several species and humans and are implicated in ovarian follicular development and atresia, ovulation, steroidogenesis, and corpus luteum function (including formation, development, and regression). The principal abnormal processes affected by these cytokines are ovarian cancer and reduction of ovarian function during sepsis.

METHODS

A literature review.

RESULTS

Numerous studies indicate that TNF and IL-1 inhibit gonadotropin-stimulated steroidogenesis of undifferentiated ovarian cells due to inhibition of adenylyl cyclase and post-cAMP sites. In differentiated ovarian cells, these cytokines either stimulate progesterone synthesis or have little to no effect on steroidogenesis. Both cytokines participate in ovulation and levels of these cytokines increase during the preovulatory period. Endotoxin inhibits gonadotropin-stimulated ovarian steroidogenesis and follicular development and these effects are mediated, in part, by TNF and by direct effects of endotoxin on ovarian cells. IN newly formed corpora lutea, progesterone secretion is inhibited by TNF and IL-1, although each has proliferative effects. TNF also has been implicated in regression of corpora lutea because TNF stimulates prostaglandin synthesis and luteal TNF increases after initiation of the decline in progesterone secretion. TNF and IL-1 are secreted by some ovarian cancer cells and stimulate growth of these cells.

CONCLUSIONS

Thus, TNF and IL-1 are multifunctional factors affecting various ovarian processes.