Endothelin receptor antagonists: effects on extracellular matrix synthesis in primary cultures of skin fibroblasts from systemic sclerosis patients.

Endothelin-1 (ET-1) seems to enhance the pro-fibrotic protein synthesis by skin fibroblasts and its effects are mediated by endothelin-A and B (ETA and ETB) receptors. This study aimed to investigate the effects of ETA and ETB receptor antagonists (ETARA-sitaxsentan and ETA/BRA-bosentan) on type I collagen (COL-1), fibronectin (FN) and fibrillin-1 (FBL-1) synthesis in primary cultures of skin fibroblasts from systemic sclerosis patients. Primary cultures of fibroblasts were obtained from skin biopsies of 6 female systemic sclerosis patients and were treated with ET-1 (100 nM) for 24 and 48 hrs with or without pre-treatment (1 hr) with ETARA (2 µM) or ETA/BRA (10 µM). Primary culture of human scleroderma skin fibroblasts not treated with ET-1 or ET receptor antagonists (ETARA and ETA/BRA) were used as controls. COL-1, FN and FBL-1 synthesis was evaluated by immunocytochemistry and Western blot analysis. Immunocytochemistry and Western blot analysis showed that ET-1 significantly increased COL-1 and FN synthesis at 24 and 48 hrs and FBL-1 synthesis at 48 hrs vs untreated cells. ETARA significantly contrasted the ET-1-mediated increase in COL-1 and FN at 24 hrs as well as COL-1 and FBL-1 at 48 hrs, but not FN synthesis vs ET-1-treated fibroblasts. Conversely, ETA/BRA significantly antagonized the ET-1-mediated overproduction of COL-1 and FN both at 24 and 48 hrs and the FBL-1 synthesis at 48 hrs vs ET-1-treated cells. The single ETARA treatment seems to contrast significantly the increase in COL-1 synthesis, whereas the dual ETA/BRA treatment seems active in significantly antagonizing both COL-1 and FN overproduction induced by ET-1. In conclusion, ET-1 antagonism might have positive effects in contrasting the profibrotic activity of systemic sclerosis skin fibroblasts.

[CTLA4-Ig interferes and downregulates the proinflammatory activities of rheumatoid synovial macrophages in monoculture]. / CTLA4-Ig influenza e inibisce le attività proinfiammatorie di macrofagi sinoviali reumatoidi in monocoltura.

OBJECTIVE: CTLA4-Ig, a biologic agent employed in rheumatoid arthritis (RA) treatment, downregulates the immune response and exerts anti-inflammatory effects acting on different cells including dendritic/T cells interaction and directly on osteoclasts. We investigated the anti-inflammatory effects of CTLA4-Ig in primary monocultures of RA synovial macrophages (SM). METHODS: SM were obtained, from 8 RA patients (7 F, 1 M; DAS28>5.2) who underwent therapeutic arthroscopic synoviectomy and were cultured in the absence and in the presence of CTLA4-Ig at the concentration of [500 microg/ml], the most reliable dose related to the previous pharmacological clinical and experimental experiences. Inflammatory cytokine (IL-6, TNFalpha, IL-1beta) expression was evaluated by immunocytochemistry (ICC with relative image analysis), western blot (WB), and quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: ICC analysis revealed that CTLA4-Ig treatment significantly downregulated cytokine expression (p<0.001 for IL-6, TNFalpha and IL-1beta) when compared to untreated RA SM. WB and qRT-PCR confirmed partially the data. CONCLUSIONS: CTLA4-Ig was found to exert a direct and significant anti-inflammatory effect on primary monocultures of RA SM, suggesting a therapeutic power in different phases of the disease activity.

Endothelin and sex hormones modulate the fibronectin synthesis by cultured human skin scleroderma fibroblasts.

OBJECTIVE: To evaluate the influence of endothelin-1 (ET-1) and sex hormones on cell proliferation and extracellular matrix (ECM) synthesis (ie, fibronectin, laminin) by cultured normal and scleroderma (SSc) human skin fibroblasts (FBs). METHODS: Primary cultures of FBs were treated with ET-1 and sex hormones (17beta-oestradiol or testosterone) for 24 h. Cell growth was analysed by methiltetrazolium salt test, ECM synthesis was evaluated by immunocytochemistry and western blot, both at 24 h. RESULTS: In normal FBs, ET-1 and 17beta-oestradiol, as well as their combination, increased cell growth (p<0.001, p<0.001, p<0.01 vs untreated cells (control), respectively) and fibronectin synthesis (p<0.05, p<0.05, p<0.01 vs control, respectively). By contrast, testosterone either alone or in combination with ET-1 did not influence cell proliferation, but decreased fibronectin synthesis (p<0.05, testosterone vs control). In SSc FBs, ET-1 and 17beta-oestradiol alone or their combination induced an increased fibronectin synthesis (p<0.05, p<0.05, p<0.01 vs control, respectively). Unexpectedly, testosterone induced an increase of fibronectin synthesis (p<0.05 vs control). CONCLUSIONS: ET-1 and 17beta-oestradiol seem to exert a profibrotic effect in normal and SSc culture FBs and might suggest their synergistic effect in the pathogenesis of the fibrotic process in SSc.

Hydroxylated estrogen metabolites influence the proliferation of cultured human monocytes: possible role in synovial tissue hyperplasia.

INTRODUCTION: 17Beta-estradiol, estrone, and several of their hydroxylated metabolites, have been found to be significantly increased in synovial fluid of rheumatoid arthritis (RA) patients. In this study, we investigated whether the estrogen metabolites are able to exert direct effects on monocyte cell proliferation, which is important in RA synovial tissue activation and growth. METHODS: Human monocytes (THP-1) were treated with the following estrogen metabolites at different concentrations (from 10-8M, 10-9M, 10-10M to 10-11M) for 24, 48 and 72 hours: 16-hydroxyestrone (16OH-E1), 16-hydroxyestradiol (16OH-E2), 4-hydroxyestrone (4OH-E1), 4-hydroxyestradiol (4OH-E2), 2-hydroxyestrone (2OH-E1) and 2-hydroxyestradiol (2OH-E2). Monocytes were activated with interferon-gamma (INF-gamma). Cell cultures were also performed in presence of tamoxifen (10-7M) to evaluate whether the estrogen metabolites act through the estrogen receptors (ER). Cell growth was detected by MTT test and cell viability through the LDH release assay. RESULTS: 4OH-E1 and 2OH-E1 significantly increased cell growth at low concentration (10-10M), whereas they significantly reduced cell proliferation at high concentrations (10-9M). 16OH-E2 and 4OH-E2 induced opposite effects: cell proliferation at high concentration and antiproliferative action at low doses. On the contrary, 16OH-E1 and 2OH-E2 were found to be estrogen metabolites that induced cell proliferative effects for most of the tested doses. Tamoxifen caused the loss of effects on cell proliferation for almost all the metabolites. CONCLUSION: This study first demonstrates that different downstream estrogen metabolites interfere with monocyte proliferation and generally might modulate the immune response. Therefore, since estrogen metabolite/ratios are altered in the synovial fluid of RA patients, they might play important roles at least in RA synovial tissue hyperplasia.

Myostatin mediates abdominal aortic atherosclerosis progression by inducing vascular smooth muscle cell dysfunction and monocyte recruitment.

Myostatin (Mstn) is a skeletal muscle growth inhibitor involved in metabolic disorders and heart fibrosis. In this study we sought to verify whether Mstn is also operative in atherosclerosis of abdominal aorta. In human specimens, Mstn expression was almost absent in normal vessels, became detectable in the media of non-progressive lesions and increased with the severity of the damage. In progressive atherosclerotic lesions, Mstn was present in the media, neointima, plaque shoulder and in infiltrating macrophages. Mstn co-localized with α-smooth muscle actin (α-SMA) staining and with some CD45+ cells, indicating Mstn expression in VSMCs and bloodstream-derived leukocytes. In vitro, Mstn was tested in VSMCs and monocytes. In A7r5 VSMCs, Mstn downregulated proliferation and Smoothelin mRNA, induced cytoskeletal rearrangement, increased migratory rate and MCP-1/CCR2 expression. In monocytes (THP-1 cells and human monocytes), Mstn acted as a chemoattractant and increased the MCP-1-dependent chemotaxis, F-actin, α-SMA, MCP-1 and CCR2 expression; in turn, MCP-1 increased Mstn mRNA. Mstn induced JNK phosphorylation both in VSMCs and monocytes. Our results indicate that Mstn is overexpressed in abdominal aortic wall deterioration, affects VSMCs and monocyte biology and sustains a chronic inflammatory milieu. These findings propose to consider Mstn as a new playmaker in atherosclerosis progression.

Altered circadian rhythms in rheumatoid arthritis patients play a role in the disease's symptoms.

The circadian changes in the metabolism or nocturnal secretion of endogenous corticosteroids (reduction) observed in rheumatoid arthritis (RA) patients are responsible, in part, for the time-dependent changes that are observed in the inflammatory response and related early morning clinical symptoms of the disease. Melatonin (MLT), another circadian nocturnal hormone that is the secretory product of the pineal gland, has been implicated in the time-dependent RA inflammatory reaction with effects that are opposite to those of corticosteroids. As a consequence, altered functioning of the HPA axis (early morning reduced corticosteroid production) and of the pineal gland (night increased MLT production) found in RA patients, seem to be important factors in the appearance and perpetuation of the clinical circadian symptoms of the disease. Consistently, human proinflammatory Th1-type cytokine production (related to MLT stimulation) exhibits a diurnal rhythmicity with peak levels during the night and early morning, at a time when plasma cortisol (inducing the Th2-type cytokine production) is lowest and MLT is highest. Reduced daily light exposure as observed in northern Europe (Estonia), at least during the winter, might explain the higher and more prolonged serum MLT concentrations that were observed in northern RA patients, as well as some epidemiological features versus southern Europe patients.

[Effects of estrogen peripheral metabolism in rheumatoid arthritis]. / Effetti del metabolismo periferico degli estrogeni nell'artrite reumatoide.

It is well known that the immune reactivity is modulated by gender. In fact, women show a more effective immune response as well as a more frequent development of autoimmune diseases. In particular, 17 beta-estradiol (E2) in patients with systemic inflammatory diseases leads to an higher production of IgG and IgM in peripheral blood mononucleated cells (PBMC) and the secretion of metalloproteinases and IL-6 by synovial fibroblasts. The effect of E2 seems to be partially related to its concentration. In fact, at the physiological concentration, E2 seems to exert a pro-inflammatory effect, while at pharmacological concentrations shows anti-inflammatory effects. Steroid hormones can be converted in downstream hormones along defined pathways. The conversion of dehydroepiandrosterone (DHEA) in peripheral macrophages leads to the androgen production. Subsequently the enzyme aromatase converts androgens in estrogens, and its activity is increased by some inflammatory cytokines such as IL-1beta, IL-6 and TNF-alpha. In the synovial fluids of rheumatoid arthritis (RA) patients the levels of estrogens result significantly increased compared with controls, showing the consequence of this unbalanced steroid metabolism. Furthermore, the metabolism of estrogens leads to some downstream hydroxylated metabolites, that are not waste products, but still active molecules in the inflammatory response. In fact, it has been found that synovial fluids of RA patients present a different ratio of 16-hydroxylated estrogen metabolites/ 2-hydroxylated metabolites, confirming that also the unbalanced metabolism of estrogens and not only the estrogen concentration seems to be related to the development and worsening of rheumatoid arthritis.

Androgen and estrogen receptors are present in primary cultures of human synovial macrophages.

Macrophages, as antigen-processing and -presenting cells to T lymphocytes, play a key role in the immune system and are suspected to be target cells of the sex hormone-related dimorphism in the immune response peculiar to rheumatoid arthritis (RA) pathology. In the present study, the use of specific monoclonal antibodies revealed immunostaining for androgen and estrogen receptors in primary cultures of macrophages obtained from synovial tissues of patients affected by RA and controls without RA disease. Soluble and nuclear type I (high affinity, low capacity) and type II (lower affinity, greater capacity) sites of androgen or estrogen binding were detected in primary cultures of RA macrophages using radioligand binding assay. Higher levels of type I and type II estrogen receptor compared to those of androgen receptor were found, particularly in the soluble fraction; however, contrary to what was observed in whole synovial tissues, higher steroid receptor concentrations were found in the soluble than in the nuclear fraction of RA synovial macrophages. Binding affinities and receptor contents of cultured synovial macrophages were comparable to those previously reported in other well established sex hormone-responsive cells and tissues. Further, specific messenger ribonucleic acids for sex hormone receptors, encoding for a sequence of the DNA-binding domain of the receptor proteins were revealed by RT-PCR.

Melatonin influences interleukin-12 and nitric oxide production by primary cultures of rheumatoid synovial macrophages and THP-1 cells.

Because some of the clinical symptoms related to rheumatoid arthritis (RA) synovitis, such as joint morning stiffness and gelling, might be related to the effects exerted by the diurnal rhythmicity of the neurohormone melatonin (MLT) on synovial immune cell activation, we decided to evaluate the influence of MLT on the production of IL-12 and nitric oxide (NO) on primary cultures of RA synovial macrophages. Synovial macrophages were also prestimulated with lipopolysaccaride (LPS). Results were compared with those obtained on cultured human myeloid monocytic cells (THP-1). A significant increase in IL-12 (p = 0.01) was found in media of MLT-stimulated synovial macrophages versus RMPI-treated synovial macrophage controls. Interestingly, a significant decrease of IL-12 (p < 0.0001) was observed in media of synovial macrophages previously activated with LPS and then treated with MLT, when compared to synovial macrophages treated with LPS alone. A significant increase in NO levels (p = 0.01) was found in MLT-stimulated synovial macrophages versus RMPI-treated synovial macrophage controls. Interestingly, a nonsignificant increase of NO levels was observed in media of synovial macrophages previously activated with LPS and then treated with MLT, when compared to cynovial macrophages treated with LPS alone. Finally, a significant increase in IL-12 (p = 0.03) and NO (p = 0.002) concentrations was observed in media of MLT-stimulated THP-1 cells versus RMPI-treated controls. Our results therefore show that MLT induces IL-12 secretion and NO production by unstimulated cultured RA synovial macrophages and human monocytic myeloid THP-1 cells. The unexpected and opposite effects on IL-12 and NO production in RA synovial macrophages treated with LPS may be related to dose-dependent mechanisms exerted by MLT or to altered cell priming in RA macrophages; these are matters of our further research. This study strongly supports the role of MLT in immune response modulation and in particular suggests a close relationship between diurnal rhythmicity of neuroendocrine pathways, cytokine and reactive oxygen intermediate production by monocyte/macrophages, and synovial arthritis symptomatology, at least in RA.

Melatonin serum levels in rheumatoid arthritis.

The pineal hormone melatonin (MLT) exerts a variety of effects on the immune system. MLT activates immune cells and enhances inflammatory cytokine and nitric oxide production. Cytokines are strongly involved in the synovial immune and inflammatory response in rheumatoid arthritis (RA) and reach the peak of concentration in the early morning, when MLT serum level is higher. Nocturnal MLT serum levels were evaluated in 10 RA patients and in 6 healthy controls. Blood samples were obtained at 8 and 12 p.m., as well as at 2, 4, 6, and 8 a.m. MLT serum levels at 8 p.m. and 8 a.m. were found to be higher in RA patients than in controls (p < 0.05). In both RA patients and healthy subjects, MLT progressively increased from 8 p.m. to the first hours of the morning, when the peak level was reached (p < 0.02). However, MLT serum level reached the peak at least two hours before in RA patients than in controls (p < 0.05). Subsequently, in RA patients, MLT concentration showed a plateau level lasting two to three hours, an effect not observed in healthy controls. After 2 a.m., MLT levels decreased similarly in both RA patients and healthy subjects. Several clinical symptoms of RA, such as morning gelling, stiffness, and swelling, which are more evident in the early morning, might be related to the neuroimmunomodulatory effects exerted by MLT on synovitis and might be explained by the imbalance between cortisol serum levels (lower in RA patients) and MLT serum levels (higher in RA patients).

The hypothalamic-pituitary-adrenal and gonadal axes in rheumatoid arthritis.

The hypothalamic-pituitary-adrenal (HPA) and the hypothalamic-pituitary-gonadal (HPG) axes involvement or response to immune activation seems crucial for the control of excessive inflammatory and immune conditions such as autoimmune rheumatic diseases, including rheumatoid arthritis (RA). However, female patients seem to depend more on the HPA axis, whereas male patients seem to depend more on the HPG axis. In particular, hypoandrogenism may play a pathogenetic role in male RA patients because adrenal and gonadal androgens, both products of the HPA and HPG axes, are considered natural immunosuppressors. A significantly altered steroidogenesis of adrenal androgens (i.e., dehydroepiandrosterone sulfate, DHEAS and DHEA) in nonglucocorticoid-treated premenopausal RA patients has been described. The menopausal peak of RA suggests that estrogens and/or progesterone deficiency also play a role in the disease, and many data indicate that estrogens suppress cellular immunity, but stimulate humoral immunity (i.e., deficiency promotes cellular Th1-type immunity). A range of physical and psychosocial stressors are also implicated in the activation of the HPA axis and related HPG changes. Chronic and acute stressors appear to have different actions on immune mechanisms with experimental and human studies indicating that acute severe stressors may be even immunosuppressive, while chronic stress may enhance immune responses. The interactions between the immunological and neuroendocrine circuits is the subject of active and extensive ongoing research and might in the near future offer highly promising strategies for hormone-replacement therapies in RA.

Presence of estrogen receptors in human myeloid monocytic cells (THP-1 cell line).

OBJECTIVE: To test THP-1 cells for the presence of estrogen receptors (ER) since studies have demonstrated in vivo and in vitro, the influence of estrogens on cells involved in immune response (i.e. macrophages), and since it has been demonstrated that human myeloid monocytic THP-1 cells acquire phenotypic and functional macrophage-like features after incubation with several cytokines or pharmacological agents. DESIGN: Stimulation of THP-1 cells with phorbol myristate acetate (PMA) to prompt their differentiation into macrophage-like cells and evaluation of the possible induction of ER. METHODS: The expression of ER was analyzed by immunocytochemical assay, reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis. RESULTS: After stimulation by PMA, the human myeloid monocytic THP-1 cells showed the presence of ER, together with markers of monocytic cell differentiation such as CD68, CD54 and HLA-DR. CONCLUSION: Estrogen effects may be exerted directly through ER on monocytes/macrophages. PMA-treated THP-1 cells may constitute a useful in vitro model to determine the effects of estrogens on macrophage-like cells and their implications in the inflammatory and immune processes.

Effect of cyclosporin on apoptosis in human cultured monocytic THP-1 cells and synovial macrophages.

OBJECTIVE: Cyclosporin A (CyA) is an immunosuppressant drug used for the treatment of rheumatoid arthritis (RA), that might affect programmed cell death (apoptosis) of the cells involved in the synovial inflammatory reaction. The effects of CyA on apoptosis were evaluated on cultured human monocytic myeloid cells (THP-1 cell line) and on RA synovial macrophages. METHODS: In order to induce THP-1 cell differentiation into adherent cells, an amount of these was treated with human recombinant IFN-gamma before incubation with CyA. Primary cultures of synovial macrophages were obtained from RA patients and treated in vitro with CyA. RESULTS: CyA, at the pharmacological range (100-300 ng/ml) employed in the treatment of RA, seems to induce, after 48-96 hrs, programmed cell death in differentiating THP-1 cells, whereas cultured synovial macrophages (fully differentiated monocytic cells) do not show any apoptosis at the same time. CONCLUSION: Short-term CyA treatment may induce increased apoptosis in immature and differentiating cultured monocytes. Cultured synovial macrophages (resident monocytic-derived and differentiated cells) seem to be resistant to the treatment as far as apoptosis is concerned.

New roles for estrogens in rheumatoid arthritis.

Sex hormones appear to play an important role as modulators of autoimmune disease onset/perpetuation. Steroid hormones are implicated in the immune response, with estrogens as enhancers at least of humoral immunity, and androgens and progesterone (and glucocorticoids) as natural immune suppressors. Serum levels of estrogens have been found to be normal in rheumatoid arthritis (RA) patients. Synovial fluid levels (SF) of proinflammatory estrogens relative to androgens are significantly elevated in both male and female RA patients as compared to controls, which is most probably due to an increase in local aromatase activity. Thus, available steroid pre-hormones are rapidly converted to proinflammatory estrogens in the synovial tissue in the presence of inflammatory cytokines (i.e. TNF alpha, IL-1, IL-6). The increased estrogen concentrations observed in RA SF of both sexes are characterized mainly by the hydroxylated forms, in particular 16 alpha-hydroxyestrone, showing a mitogenic stimulating role. Indeed, recent studies by us indicate that 17-beta estradiol (E2) clearly enhanced the expression of markers of cell growth and proliferation, whereas testosterone (T) induced an increase in markers indicating DNA damage and apoptosis. In particular, our data further shows that the enhancing role of estrogens on the immune/inflammatory response is exerted by activating the NFkB complex. In conclusion, locally increased estrogens may exert activating effects on synovial cell proliferation, including macrophages and fibroblasts, suggesting new roles for estrogens in RA.

Fundus angiography with fluorescein-labelled peptide fraction from bovine factor VIII: correlation with histologic findings.

A peptide fraction (VUEFFE) obtained from bovine factor VIII, with a high affinity for vessel endothelium, was bound to fluorescein and used for angiography in rabbits. Several eyes had undergone laser photocoagulation on the retina. The location of the dye was studied histologically with fluorescence microscopy on the enucleated, freeze-dried eyes. The angiographic and histologic findings were compared with findings obtained using sodium fluorescein. Fluorescein-labelled VUEFFE gave a longer lasting fluorescence of the retinal vessels with histologic evidence of dye deposition on the vessel wall. It also showed marked affinity for the photocoagulated tissues, giving intense and prolonged staining of the laser burns. Possible clinical applications are discussed.

Evaluation of metabolic acidosis in patients with a kidney graft: comparison of the bicarbonate-based and strong ion-based methods.

BACKGROUND: According to the traditional bicarbonate-based approach, metabolic acidosis is highly prevalent in kidney transplant recipients. However, the bicarbonate-based approach has been questioned by intensivists using strong ion difference-based methods. METHODS: We compared the results obtained by the strong ion-based with the traditional approach based on bicarbonate among a cohort of 83 kidney transplant recipients. RESULTS: Fifty-five percent of the patients were acidotic based on venous bicarbonate (<23 mmol/L) and 49% by the use of the effective strong ion difference (SID(effective)) (<37 mmol/L). Bicarbonate and SID(effective) were linearly correlated (r=0.94; P<.0001), with a slope close to 1. A greater percentage of patients presented with an increase in unexplained anions by the strong ion gap (SIG) than by the anion gap corrected (AG(corrected)) method (42 vs 32%, respectively). AG(corrected) and SIG were directly related (r=0.919; P<.0001), but the best fit of the relationship was polynomial with a progressively greater effect on SIG with increased AG(corrected), suggesting that as anions progressively accumulate, their detection by SIG increases. By multiple regression analysis, plasma chloride, potassium, uric acid, and phosphate predicted blood bicarbonate. Analogously, chloride, potassium and uric acid predicted SID(effective). Age was a predictor of changes in AG(corrected), whereas age and plasma urea predicted SIG. CONCLUSIONS: The use of the SID yielded results that were similar to the traditional bicarbonate-based approach. Conversely, SIG appeared to be more sensitive than AG for detection of anion accumulation among patients with a kidney graft.