Cytokines in chronic inflammatory arthritis. II. Granulocyte-macrophage colony-stimulating factor in rheumatoid synovial effusions

GM-CSF upregulated in rheumatoid arthritis reverses cognitive impairment and amyloidosis in Alzheimer mice

Rheumatoid arthritis (RA) is a negative risk factor for the development of Alzheimer's disease (AD). While it has been commonly assumed that RA patients' usage of non-steroidal anti-inflammatory drugs (NSAIDs) helped prevent onset and progression of AD, NSAID clinical trials have proven unsuccessful in AD patients. To determine whether intrinsic factors within RA pathogenesis itself may underlie RA's protective effect, we investigated the activity of colony-stimulating factors, upregulated in RA, on the pathology and behavior of transgenic AD mice. 5 microg bolus injections of macrophage, granulocyte, and granulocyte-macrophage colony-stimulating factors (M-CSF, G-CSF, or GM-CSF) were administered unilaterally into the hippocampus of aged cognitively-impaired AD mice and the resulting amyloid load reductions determined one week later, using the artificial cerebrospinal fluid-injected contralateral sides as controls. G-CSF and more significantly, GM-CSF reduced amyloidosis throughout the treated brain hemisphere one week following bolus administration to AD mice. 20 daily subcutaneous injections of 5 microg of GM-CSF (the most amyloid-reducing CSF in the bolus experiment) were administered to balanced cohorts of AD mice after assessment in a battery of cognitive tests. Reductions in amyloid load and improvements in cognitive function were assessed. Subcutaneous GM-CSF administration significantly reduced brain amyloidosis and completely reversed the cognitive impairment, while increasing hippocampal synaptic area and microglial density. These findings, along with two decades of accrued safety data using Leukine, recombinant human GMCSF, in elderly leukopenic patients, suggest that Leukine should be tested as a treatment to reverse cerebral amyloid pathology and cognitive impairment in AD.

Hematopoietic colony-stimulating factors: new players in tumor-nerve interactions

A variety of cancers are accompanied by debilitating pain, which constitutes the primary reason for poor quality of life in cancer patients. There is an urgent demand for the development of specific mechanism-based therapies against cancer pain. Recently, important advances have been made in mechanisms contributing to cancer pain. A notable finding was that the tumor-derived hematopoietic growth factors, granulocyte- and granulocyte-macrophage-colony-stimulating factors (G-CSF/GM-CSF), subserve important functions in the generation of pain hypersensitivity in tumor-affected regions. In this context, their receptors were unexpectedly found on pain-sensing nerves and were observed to be functionally linked to nociceptive sensitization and tumor-induced pain. Here, we review evidence supporting a role for G-/GM-CSF in sensitization of pain-sensing nerves, the underlying signaling pathways and the cross-talk with other pronociceptive cytokines, peptides and modulators derived from immune cells, osteoclasts and tumor cells. These findings hold implications in the therapy of pain in disease states, such as cancer and rheumatoid arthritis.

Implication of granulocyte-macrophage colony-stimulating factor induced neutrophil gelatinase-associated lipocalin in pathogenesis of rheumatoid arthritis revealed by proteome analysis

Introduction

In rheumatoid arthritis (RA), synovial fluid (SF) contains a large number of neutrophils that contribute to the inflammation and destruction of the joints. The SF also contains granulocyte-macrophage colony-stimulating factor (GM-CSF), which sustains viability of neutrophils and activates their functions. Using proteomic surveillance, we here tried to elucidate the effects of GM-CSF on neutrophils.

Methods

Neutrophils stimulated by GM-CSF were divided into four subcellular fractions: cytosol, membrane/organelle, nuclei, and cytoskeleton. Then, proteins were extracted from each fraction and digested by trypsin. The produced peptides were detected using matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF MS).

Results

We detected 33 peptide peaks whose expression was upregulated by more than 2.5-fold in GM-CSF stimulated neutrophils and identified 11 proteins out of the 33 peptides using MALDI-TOF/TOF MS analysis and protein database searches. One of the identified proteins was neutrophil gelatinase-associated lipocalin (NGAL). We confirmed that the level of NGAL in SF was significantly higher in patients with RA than in those with osteoarthritis. We next addressed possible roles of the increased NGAL in RA. We analysed proteome alteration of synoviocytes from patients with RA by treatment with NGAL in vitro. We found that, out of the detected protein spots (approximately 3,600 protein spots), the intensity of 21 protein spots increased by more than 1.5-fold and the intensity of 10 protein spots decreased by less than 1 to 1.5-fold as a result of the NGAL treatment. Among the 21 increased protein spots, we identified 9 proteins including transitional endoplasmic reticulum ATPase (TERA), cathepsin D, and transglutaminase 2 (TG2), which increased to 4.8-fold, 1.5-fold and 1.6-fold, respectively. Two-dimensional electrophoresis followed by western blot analysis confirmed the upregulation of TERA by the NGAL treatment and, moreover, the western blot analysis showed that the NGAL treatment changed the protein spots caused by post-translational modification of TERA. Furthermore, NGAL cancelled out the proliferative effects of fibroblast growth factor (FGF)-2 and epidermal growth factor (EGF) on chondrocytes from a patient with RA and proliferative effect of FGF-2 on chondrosarcoma cells.

Conclusions

Our results indicate that GM-CSF contributes to the pathogenesis of RA through upregulation of NGAL in neutrophils, followed by induction of TERA, cathepsin D and TG2 in synoviocytes. NGAL and the upregulated enzymes may therefore play an important role in RA.

Immigration check for neutrophils in RA lining: laminin alpha5 low expression regions act as exit points

OBJECTIVE

A correlation exists between the absence of alpha5-laminin and transit checkpoint fenestrations in vascular basement membranes. We hypothesized that similar laminin alpha5 low expression regions might exist in synovial lining, which, although lacking basement membrane, contains all basement membrane components in its interstitial matrix.

METHODS

Laminin alpha4 and alpha5 chains and lactoferrin were stained using immunofluorescence and cathepsin G and neutrophil elastase using immunoperoxidase. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure laminin alpha4 and alpha5 mRNA copy numbers in cultured synovial fibroblasts, without/with tumour necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta).

RESULTS

Laminin alpha4 and alpha5 chains were found in the intercellular matrix in synovial lining samples of trauma and revision total hip replacements. Laminin alpha5 was weaker in osteoarthritis (OA) and rheumatoid arthritis (RA), and RA synovial lining also contained local low expression areas. Double staining disclosed convergence of lactoferrin-degranulating neutrophils towards these laminin alpha5 low expression regions. In cultured OA synovial fibroblasts, laminin alpha5 mRNA decreased (p < 0.05) at 1 ng/mL TNFalpha and was not found at all in cultured resting or cytokine-stimulated RA fibroblasts. Degranulation of cathepsin G and neutrophil elastase was seen in neutrophils passing through blood vessels or synovial lining.

CONCLUSIONS

Migrating neutrophils in RA seem to use laminin alpha5 chain low expression regions to exit synovial tissue to enter synovial fluid. Transmigrating neutrophils remodel the intercellular matrix by releasing their proteolytic granular contents to enhance these low expression checkpoints and/or to produce chemotactic stimuli. In RA fibroblasts this is facilitated by cytokine-mediated down-regulation or lack of laminin alpha5 synthesis.

Pulmonary alveolar proteinosis, a primary immunodeficiency of impaired GM-CSF stimulation of macrophages

Pulmonary alveolar proteinosis (PAP) is a rare syndrome characterized by accumulation of pulmonary surfactant, respiratory insufficiency, and increased infections. It occurs in various clinical settings that disrupt surfactant catabolism in alveolar macrophages, including a relatively more common autoimmune disease caused by GM-CSF autoantibodies and a rare congenital disease caused by CSF2RA mutations. Recent results demonstrate that GM-CSF is crucial for alveolar macrophage terminal differentiation and immune functions, pulmonary surfactant homeostasis, and lung host defense. GM-CSF is also required to determine the basal functional capacity of circulating neutrophils, including adhesion, phagocytosis, and microbial killing. PAP research has illuminated the crucial role of GM-CSF in innate immunity and led to novel therapy for PAP and the potential use of anti-GM-CSF therapy in other common disorders.

Non-allergic Eosinophilic Inflammation

Much is known about the eosinophilic processes associated with antigens, tumors, and infection, yet data on other causes of eosinophilic inflammation are scarce. This paper investigates the locations and causes of other nonrespiratory eosinophilic inflammation. Although eosinophilic inflammation can involve locomotor, urinary, cardiovascular, nervous, gastrointestinal, and other mucosal surfaces, such inflammation also can accompany tissue trauma, foreign-body reactions, and necrotic or granulomatous processes. Despite their cytolytic/histolytic effects, eosinophil leukocytes are a component of tissue remodeling, can be antigen-presenting cells, and have a role in the reproductive system and in blood coagulation. The study of various types of eosinophilic inflammation may increase our understanding of the biological responses of eosinophil leukocytes to different inflammatory stimuli.

Delayed apoptosis of human monocytes exposed to immune complexes is reversed by oxaprozin: role of the Akt/IkappaB kinase/nuclear factor kappaB pathway

BACKGROUND AND PURPOSE

Monocytes-macrophages play a key role in the initiation and persistence of inflammatory reactions. Consequently, these cells represent an attractive therapeutic target for switching off overwhelming inflammatory responses. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most common drugs for the symptomatic treatment of rheumatic diseases. Their effects have been explained on the basis of cyclooxygenase (COX) inhibition. However, some of the actions of these drugs are not related to inhibition of prostaglandin synthesis.

EXPERIMENTAL APPROACH

We examined the effect of oxaprozin on apoptosis of immune complex-activated monocytes in comparison with drugs of the same class, and the signalling pathway that leads activated monocytes exposed to oxaprozin to apoptosis. In particular, we studied the activity of caspase-3, the involvement of IkappaB kinase (IKK)-nuclear factor kappaB (NF-kappaB) system and the activity of X-linked mammalian inhibitor of apoptosis protein (XIAP), Akt and mitogen-activated protein kinase (MAPK) in activated monocytes in the presence of oxaprozin.

KEY RESULTS

Immune complexes caused the inhibition of monocyte apoptosis. Oxaprozin reversed in a dose-dependent manner immune complex-induced survival of monocytes, without affecting the apoptosis of resting cells. Other NSAIDs are ineffective. The activity of oxaprozin was related to inhibition of Akt activation that, in turn, prevented p38 MAPK, IKK and NF-kappaB activation. Consistently, the inhibition of NF-kappaB activation reduced the production of the anti-apoptotic molecule XIAP, leading to uncontrolled activity of caspase 3.

CONCLUSIONS AND IMPLICATIONS

These results suggest that oxaprozin exerts its anti-inflammatory activity also through COX-independent pathways. It is likely that oxaprozin-mediated inhibition of the Akt/IKK/NF-kappaB pathway contributes to its anti-inflammatory properties.

Granulocyte-macrophage colony stimulating factor is anabolic and interleukin-1beta is catabolic for rat articular chondrocytes

OBJECTIVE

To study the effects of GM-CSF and IL-1beta, both implicated in tissue damage in arthritis, on articular chondrocyte proliferation and metabolism, and to explore their agonist/antagonist effects.

METHODS

Chondrocytes were obtained from 1-month-old rats. First-passage monolayers were incubated for 24 h with or without GM-CSF and/or IL-1beta, and labeled with 3H-thymidine, 35S-SO4 and 14C-proline. Proteoglycan and collagen synthesis were analyzed by liquid chromatography and SDS-PAGE. Gene expression was measured by RT-PCR.

RESULTS

IL-1beta exerts potent, and GM-CSF weak, inhibitory effects on DNA synthesis. GM-CSF strongly stimulates, and IL-1beta inhibits, proteoglycan and collagen synthesis. IL-1beta suppresses the effect of GM-CSF, and increases the release of radioactive molecules from pre-labeled cartilage fragments; GM-CSF decreases the IL-1beta-induced effect. Interestingly, both cytokines induce the expression of each other's gene.

CONCLUSIONS

IL-1beta appears to be a catabolic and anti-anabolic agent for chondrocytes, whereas GM-CSF is mainly anabolic, and blocks the IL-1beta-induced catabolic effect. It is postulated that both agents are implicated in inflammation: IL-1beta promotes tissue catabolism and destruction, whereas GM-CSF enhances tissue reconstruction.

Responses of neutrophils to myeloid growth factors

Colony-stimulating factors (CSFs) have important effects on mature myeloid cells in addition to their regulatory role in haemopoiesis. Exposure of neutrophils to granulocyte macrophage-CSF (GM-CSF) increases chemotaxis, phagocytosis and cytotoxicity and primes the cells for enhanced oxidative metabolism in response to stimuli, such as formylated oligopeptides derived from bacteria (f-Met-Leu-Phe) and endogenous activated complement components (C5a). GM-CSF induces time-dependent changes in neutrophil f-Met-Leu-Phe receptor number and affinity that correspond to changes in functional activity. The neutrophil IgA Fc receptor is also modulated by GM-CSF such that it develops a high affinity state and transduces a phagocytic signal. The ability to regulate the number and activity of mature myeloid effector cells in vivo establishes unique therapeutic opportunities in the area of infectious disease, cancer treatment, bone marrow transplantation and augmentation of host defence in immunodeficient patients.

Pathogenesis and therapy of rheumatoid arthritis

Rheumatoid arthritis is a chronic disabling disease affecting at least 1% of the population on a worldwide basis. Research aimed at understanding the pathogenesis of this disease led to the identification of TNFalpha as a major pro-inflammatory cytokine expressed in the inflamed joints of patients with rheumatoid arthritis. Subsequently, in vitro studies provided evidence to suggest that TNFalpha played an important role in driving the expression of additional pro-inflammatory cytokines, such as IL-1, GM-CSF, IL-6, and IL-8, in synovial cell cultures. Another important finding that confirmed the pathological significance of TNFalpha was that mice genetically engineered to overexpress TNFalpha spontaneously developed arthritis. Subsequently, the therapeutic effect TNFalpha blockade was tested in animal models prior to clinical trials in human patients, which provided unequivocal verification of the validity of TNFalpha as a therapeutic target. Anti-TNFalpha therapy is now accepted as a fully-validated treatment modality for rheumatoid arthritis.

Natural killer cells trigger differentiation of monocytes into dendritic cells

Circulating monocytes can differentiate into dendritic cells (moDCs), which are potent inducers of adaptive immune responses. Previous reports show that granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 induce monocyte differentiation into moDCs in vitro, but little is known about the physiological requirements that initiate moDC differentiation in vivo. Here we show that a unique natural killer (NK) cell subset (CD3(-)CD56(bright)) that accumulates in lymph nodes and chronically inflamed tissues triggers CD14(+) monocytes to differentiate into potent T-helper-1 (T(H)1) promoting DC. This process requires direct contact of monocytes with NK cells and is mediated by GM-CSF and CD154 derived from NK cells. It is noteworthy that synovial fluid (SF) from patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA), but not osteoarthritis (OA), induces monocytes to differentiate into DC. However, this process occurs only in the presence of NK cells. We propose that NK cells play a role in the maintenance of T(H)1-mediated inflammatory diseases such as RA by providing a local milieu for monocytes to differentiate into DC.

Induction of tumour necrosis factor receptor-expressing macrophages by interleukin-10 and macrophage colony-stimulating factor in rheumatoid arthritis

Despite its potent ability to inhibit proinflammatory cytokine synthesis, interleukin (IL)-10 has a marginal clinical effect in rheumatoid arthritis (RA) patients. Recent evidence suggests that IL-10 induces monocyte/macrophage maturation in cooperation with macrophage-colony stimulating factor (M-CSF). In the present study, we found that the inducible subunit of the IL-10 receptor (IL-10R), type 1 IL-10R (IL-10R1), was expressed at higher levels on monocytes in RA than in healthy controls, in association with disease activity, while their expression of both type 1 and 2 tumour necrosis factor receptors (TNFR1/2) was not increased. The expression of IL-10R1 but not IL-10R2 was augmented on monocytes cultured in the presence of RA synovial tissue (ST) cell culture supernatants. Cell surface expression of TNFR1/2 expression on monocytes was induced by IL-10, and more efficiently in combination with M-CSF. Two-color immunofluorescence labeling of RA ST samples showed an intensive coexpression of IL-10R1, TNFR1/2, and M-CSF receptor in CD68+ lining macrophages. Adhered monocytes, after 3-day preincubation with IL-10 and M-CSF, could produce more IL-1beta and IL-6 in response to TNF-alpha in the presence of dibutyryl cAMP, as compared with the cells preincubated with or without IL-10 or M-CSF alone. Microarray analysis of gene expression revealed that IL-10 activated various genes essential for macrophage functions, including other members of the TNFR superfamily, receptors for chemokines and growth factors, Toll-like receptors, and TNFR-associated signaling molecules. These results suggest that IL-10 may contribute to the inflammatory process by facilitating monocyte differentiation into TNF-alpha-responsive macrophages in the presence of M-CSF in RA.

Positive influence of Methotrexate-Hydroxychloroquine combination on the expression of GM-CSF receptor on neutrophils of synovial fluid in rheumatoid arthritis

Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) has been inducted as a mediator of inflammation in rheumatoid arthritis. Methotrexate combination therapy forms an important component of the treatment regimen in rheumatoid arthritis. The present study was undertaken to evaluate the influence of Methotrexate-Hydroxychloroquine (MTX-HCQ) combination and Sulfsalazine- Hydroxychloroquine (SSZ-HCQ) combination on the expression GM-CSFR in neutrophils isolated from synovial fluids. 15 cases of confirmed rheumatoid arthritis patients who presented at the hospital for surgical correction of joint deformities were selected for the study. Neutrophils isolated from the synovial fluids were used as the source of the receptor for quantitation on an enzyme immunoassay (EIA). The EIA was developed and standardized in our laboratory for quantification of the GM-CSF R. The findings are suggestive of the fact that the administration of MTX-HCQ combination has positive influence on the expression of the GM-CSF R on neutrophils as against SSZ-HCQ combination. The physiological basis of this increase needs further investigation.

Extra-pulmonary aspects of acquired pulmonary alveolar proteinosis as predicted by granulocyte-macrophage colony-stimulating factor-deficient mice

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-/- mice are an invaluable model for exploring the effects of systemic GM-CSF deficiency. Their lung phenotype exactly reproduces the abnormalities seen in human pulmonary alveolar proteinosis (PAP). However, GM-CSF-/- mice also have significant systemic functional abnormalities. These include immune defects which result in a reduced susceptibility to a range of experimentally induced autoimmune disorders. These immunological defects are also functionally manifest as an impaired ability to resolve a range of infections under certain conditions, usually implicating cellular effectors, including Listeria, Group B streptococcus, adenovirus, Pneumocystis carinii, and malaria. These observations are consistent with the known propensity for patients with PAP to develop a range of opportunistic infections. Conversely, the diminished immunological response to inflammatory stimuli may be beneficial in some settings by limiting inflammatory cell recruitment and pro-inflammatory mediator-release. GM-CSF-/- mice also have distinct fertility defects, manifest as reduced litter size and an increased rate of early fetal loss. These observations may be clinically relevant for women affected by PAP and further support the evaluation of the role of GM-CSF in human reproduction. These observations reinforce the importance of clinicians viewing PAP as a state of systemic functional GM-CSF deficiency, albeit with prominent pulmonary manifestations, rather than purely a 'lung disease'. These systemic manifestations of GM-CSF deficiency should also be considered when deciding on the choice between pulmonary or systemic delivery of GM-CSF as therapy for PAP, as only systemic drug delivery has the potential capacity to correct the systemic manifestations of GM-CSF deficiency in these patients.

The importance of T cell interactions with macrophages in rheumatoid cytokine production

The analysis of suppression of cytokines in rheumatoid synovial tissue and fluid pioneered the studies of human cytokines in diseased tissue due to the relative ease of staining samples, even at the height of the inflammatory process. These studies led to the study of synovial cytokine regulation, and the identification of TNF as a therapeutic target, which has been amply validated in clinical trials and now routine therapy. The next key question was how is TNF disregulated in synovium. Are there differences between the mechanisms of synovial TNF production compared to the production of protective TNF during an immune response? Are there differences between the induction of the pro-inflammatory TNF and the anti inflammatory IL-10? The analysis of the interaction of the two most abundant synovial cells, T lymphocytes and macrophages has provided interesting clues to new therapeutic approaches based on disrupting T-macrophage interaction.

Pathogenesis of rheumatoid arthritis: how early is early?

Studies of cytokine expression in rheumatoid arthritis have provided key insights into the pathogenesis of disease and have offered clues for effective therapy. Patterns of T-cell products in chronic rheumatoid synovitis suggest that T helper type 1 cells contribute to the perpetuation of disease. However, there is no guarantee that the mechanisms of late disease are identical to very early rheumatoid arthritis. Evaluation of the cytokine profile at the earliest time points after onset of symptoms could identify novel targets that prevent progression to chronic arthritis.

CCL3 (MIP-1α) induces in vitro migration of GM-CSF-primed human neutrophils via CCR5-dependent activation of ERK 1/2

CCL3 (MIP-1alpha), a prototype of CC chemokines, is a potent chemoattractant toward human neutrophils pre-treated with GM-CSF for 15 min. GM-CSF-treated neutrophils migrate also to the selective CCR5 agonist CCL4 (MIP-1beta). CCL3- and CCL4-triggered migration of GM-CSF-primed neutrophils was inhibited by the CCR5 antagonist TAK-779. Accordingly, freshly isolated neutrophils express CCR5. Extracellular signal-regulated kinases (ERK)-1/2 and p38 mitogen-activated protein kinase (MAPK) inhibitors blocked CCL3-induced migration of GM-CSF-primed neutrophils. When the activation of ERK-1/2 and p38 MAPK by CCL3 and the classical neutrophilic chemokine CXCL8 (IL-8) were compared, both the chemokines were capable of activating p38 MAPK. On the contrary, whereas both ERK-1 and ERK-2 were activated by CXCL8, no ERK-1 band was detectable after CCL3 triggering. Finally, neutrophil pre-treatment with GM-CSF activated both ERK-1 and ERK-2. This suggests that by activating ERK-1, GM-CSF renders neutrophils rapidly responsive to CCL3 stimulation throughout CCR5 which is constitutively expressed on the cell surface.

Synovial fluid neutrophils transcribe and express class II major histocompatibility complex molecules in rheumatoid arthritis

OBJECTIVE

To investigate a potential interaction between neutrophils and T cells in rheumatoid arthritis (RA), by defining the optimal conditions for induction of class II major histocompatibility complex (MHC) expression on peripheral blood neutrophils in vitro and investigating the capacity for neutrophils to express class II MHC molecules in RA.

METHODS

Surface expression of class II MHC and costimulatory molecules by peripheral blood and synovial fluid (SF) neutrophils obtained from healthy controls and patients with RA was measured by flow cytometry and fluorescence microscopy. Intracellular class II MHC protein and messenger RNA (mRNA) were detected by Western blotting and Northern blotting, respectively.

RESULTS

Freshly isolated peripheral blood neutrophils from controls did not express surface class II MHC; expression was induced by culture with appropriate cytokines. Freshly isolated peripheral blood neutrophils from patients with RA expressed mRNA, but there was no surface expression of class II MHC. Freshly isolated SF neutrophils from patients with RA contained high levels of class II MHC mRNA, did not express surface class II MHC, but did have large intracellular amounts of this protein as detected by Western blotting. After culture for 20 hours in vitro, SF neutrophils from RA patients expressed large amounts of surface class II MHC but very low levels of costimulatory molecules CD80 and CD86. Fluorescence microscopy localized surface class II MHC to discrete areas on the neutrophil. Class II MHC-expressing neutrophils stimulated T cell proliferation.

CONCLUSION

Peripheral blood neutrophils from patients with RA but not healthy controls express class II MHC mRNA. SF neutrophils in RA synthesize and express large amounts of class II MHC but not costimulatory molecules. This might underlie a novel interaction with T cells that is important in terms of disease pathology.

Regulation of the class II MHC pathway in primary human monocytes by granulocyte-macrophage colony-stimulating factor

GM-CSF stimulates the growth and differentiation of hematopoietic progenitors and also affects mature cell function. These effects have led to the use of GM-CSF as a vaccine adjuvant with promising results; however, the mechanisms underlying GM-CSF-mediated immune potentiation are incompletely understood. In this study, we investigated the hypothesis that the immune stimulatory role of GM-CSF is in part due to effects on class II MHC Ag presentation. We find that, in primary human monocytes treated for 24-48 h, GM-CSF increases surface class II MHC expression and decreases the relative level of the invariant chain-derived peptide, CLIP, bound to surface class II molecules. GM-CSF also increases expression of the costimulatory molecules CD86 and CD40, but not the differentiation marker CD1a or CD16. Furthermore, GM-CSF-treated monocytes are better stimulators in a mixed leukocyte reaction. Additional analyses of the class II pathway revealed that GM-CSF increases total protein and RNA levels of HLA-DR, DM, and DOalpha. Expression of class II transactivator (CIITA) types I and III, but not IV, transcripts increases in response to GM-CSF. Furthermore, GM-CSF increases the amount of CIITA associated with the DR promoter. Thus, our data argue that the proinflammatory role of GM-CSF is mediated in part through increased expression of key molecules involved in the class II MHC pathway via induction of CIITA.

Immune responses in cancer

The complex of humoral factors and immune cells comprises two interleaved systems, innate and acquired. Immune cells scan the occurrence of any molecule that it considers to be nonself. Transformed cells acquire antigenicity that is recognized as nonself. A specific immune response is generated that results in the proliferation of antigen-specific lymphocytes. Immunity is acquired when antibodies and T-cell receptors are expressed and up-regulated through the formation and release of lymphokines, chemokines, and cytokines. Both innate and acquired immune systems interact to initiate antigenic responses against carcinomas. A new approach to the treatment of cancer has been immunotherapy, which aims to up-regulate the immune system in order that it may better control carcinogenesis. Currently, several forms of immunotherapy that use natural biological substances to activate the immune system are being explored therapeutically. The various forms of immunotherapy fall into three main categories: monoclonal antibodies, immune response modifiers, and vaccines. While these modalities have individually shown some promise, it is likely that the best strategy to combat cancer may require multiple immunotherapeutic strategies in order to demonstrate benefit in different patient populations. It may be that the best results are obtained with vaccines in combination with a variety of immunotherapy combinations. Another potent strategy may be in combining with more traditional cancer drugs as evidenced from the benefit derived from enhancing the efficacy of chemotherapy with cytokines. Through such concerted efforts, a durable, therapeutic antitumour immune response may be achieved and maintained over the course of a patient's lifespan.

Protective role of n-3 lipids and soy protein in osteoporosis

It is well established that bone loss due to estrogen deficiency after menopause is greater in women consuming higher quantities of animal protein than in women consuming vegetable protein, particularly soy protein. Besides the dietary protein source altering bone loss, it has also been postulated recently that the source of a higher n-6/n-3 ratio in dietary oils is implicated in causing osteoporosis. Both animal and human studies have indicated that an increased intake of n-6 fatty acids from vegetable oils elevates prostaglandin E(2) levels as well as pro-inflammatory cytokines such as IL-1, IL-6 and TNF-alpha. Interestingly, it has been found that lack of estrogen also increases the production of these cytokines by immune cells and thereby activates osteoclasts during the peri-menopausal period. We speculated that the use of n-3 fatty acids and soy protein, which are known to act as anti-inflammatory and down regulate pro-inflammatory cytokines, may also protect against bone loss by decreasing osteoclast activation and bone resorption. Similar to the results of others, our ongoing studies indeed show that the bone loss in ovariectomized mice is significantly attenuated by feeding diets enriched with either fish oil or soy protein when compared to corn oil and casein-fed mice. One of the mechanisms appears to be decreasing the activation of receptor activator of NF-kappaB ligand (RANKL) on T cells, which has been found to increase osteoclast activation along with increasing pro-inflammatory cytokines in OVX mice. Since hormone replacement therapy has been found to cause adverse effects, further both animal and human studies are required with moderate soy protein and fish oil supplements in understanding the mechanisms involved in altering immune function and bone loss during menopause in women and aging in men.

Induction of CD69 activation molecule on human neutrophils by GM-CSF, IFN-gamma, and IFN-alpha

The CD69 glycoprotein is an early activation antigen of T and B lymphocytes but it expression is induced in vitro on cells of most hematopoietic lineages, including neutrophils after stimulation with PMA or fMLP. In this study, we investigated whether CD69 expression on human neutrophils could be modulated by inflammatory or anti-inflammatory cytokines (IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, G-CSF, GM-CSF, TNF-alpha, TGF-beta, IFN-alpha, IFN-gamma). Resting neutrophils from healthy subjects did not express CD69 on the cell surface; moreover, a preformed intracellular pool of CD69 was not evident in these cells. CD69 was barely detectable on these cells after overnight incubation in medium while overnight incubation with GM-CSF, IFN-gamma or IFN-alpha significantly induced CD69 expression on neutrophils with GM-CSF appearing to be the most potent inducer. This induction was dependent on a new protein synthesis as it was significantly inhibited by cycloheximide (about 50% inhibition). CD69 cross-linking on GM-CSF-primed neutrophils sinergized with LPS and increased TNF-alpha production and secretion suggesting a role for CD69-positive neutrophils in the pathogenesis and maintenance of different inflammatory diseases.

Chemically modified ribozyme targeting TNF-alpha mRNA regulates TNF-alpha and IL-6 synthesis in synovial fibroblasts of patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is chronic polyarthritis in which a variety of inflammatory cytokines play a role. Since tumor necrosis factor-alpha (TNF-alpha) is one of the most important cytokines in the pathogenesis of RA, we evaluated the feasibility of ribozymes as a therapeutic agent to control the inflammatory process of RA synovium. A hammerhead ribozyme against TNF-alpha was chemically modified to increase nuclease resistance and added to RA fibroblastlike cell cultures without using a delivery system. The cellular uptake of fluorescent-labeled ribozyme into synovial cells was found to last at least 48 hr by confocal laser scanning microscopy. The ribozyme targeting TNF-alpha gene inhibited both the expression of TNF-alpha mRNA and the secretion of TNF-alpha and IL-6. The cytotoxic effect by the ribozyme on synovial cells was negligible when determined by an alamar blue assay. Chemically modified ribozymes designed to suppress the TNF-alpha gene may be potential as a therapeutic agent for rheumatoid arthritis.

Kallikrein cascade and cytokines in inflamed joints

Rheumatoid arthritis is a chronic multi-system disease of unknown aetiology. The current hypothesis is that an unknown antigen triggers an autoimmune response in a genetically susceptible individual. The predominant pathological change is that of an inflammatory synovitis, characterised by cellular infiltrates and angiogenesis, with subsequent bone and cartilage destruction. These pathological changes are as a result of the activation of a variety of cells, inflammatory mediators, and effector molecules. The pro-inflammatory kinins and cytokines appear to play a central role in the pathogenesis of rheumatoid arthritis. Sufficient evidence exists that establishes a key role for the kallikrein-kinin cascade in inflamed joints. In addition, there appears to be an inter-relationship between cytokines and kinins in the inflammatory process. Kinins induce the release of cytokines, and cytokines have been shown to augment the effects of kinins. This may lead to an enhancement and perpetuation of the inflammatory process. In this review, we report a first study, correlating markers of disease with the kallikrein-kinin cascade and with cytokines.

Dynamic changes in cytokine levels in serum and synovial fluid following filtration leukocytapheresis therapy in patients with rheumatoid arthritis

We attempted to determine whether various cytokine levels in the serum and synovial fluid (SF) of rheumatoid arthritis (RA) patients are influenced by the performance of filtration leukocytapheresis (LCP). The filtration LCP procedure that used a Cellsorba column (LCP group: n=22; responder subgroup: n=17, non-responder subgroup: n=5) or sham apheresis (control group; n=7) was repeated three times at 1-week intervals. Serum (LCP group, n=22; control group, n=7) and SF (LCP group, n=6; control group, n=3) samples were collected before and after LCP. Levels of tumor necrosis factor alpha (TNFalpha), interleukins (IL-1 beta, IL-2, IL-6, IL-8, IL-10, and IL-15), granulocyte-macrophage colony-stimulating factor (GM-CSF), monocyte chemoattractant protein-1 (MCP-1), RANTES were measured by an enzyme-linked immunosorbent assay. Serum TNF alpha, IL-15, and RANTES were significantly reduced only in the LCP group. Serum IL-10 significantly increased only in the LCP group. In the LCP subgroup, serum IL-15, GM-CSF, and RANTES levels were reduced significantly, while serum IL-10 levels increased significantly only in the responder group after treatment. Serum TNF alpha levels were reduced significantly in both subgroups. Changes in serum IL-10 correlated positively with the improvement of patient's assessment of pain and global severity, and physician's assessment of global severity. These results indicate that the removal of leukocytes from the peripheral blood of RA patients provokes dynamic changes in some cytokine levels in the serum and/or synovial fluid. These changes may explain some of the mechanisms by which the articular symptoms are improved by filtration LCP.

Discovery of TNF-alpha as a therapeutic target in rheumatoid arthritis: preclinical and clinical studies

The development of effective new treatments is greatly facilitated by the understanding of the mechanisms of disease. In rheumatoid arthritis, there has been progress in understanding its immunology, the HLA class II predisposition including the 'shared epitope' and more recently in understanding the importance of proinflammatory cytokines. Here we review our work in defining TNFalpha as a therapeutic target in rheumatoid arthritis, from an understanding of molecular pathogenesis in vitro, to formal proof in the clinic in vivo. There is now extensive clinical use of anti-TNFalpha biologicals for severe rheumatoid arthritis in the US and Europe.

Regulation of granulocyte-macrophage colony-stimulating factor in human retinal pigment epithelial cells by IL-1beta and IFN-gamma

GM-CSF production by RPE cells, which form part of the blood-retina barrier, is upregulated by IL-1beta and this increase can be reversed by IFN-gamma. IL-1beta up-regulation is not dependent on PKC but the PKC activator PMA induces low levels of GM-CSF production and acts synergistically with IL-1beta to further increase GM-CSF. Although A23187 and ionomycin stimulated low levels of GM-CSF production, the IL-1beta pathway was cyclosporin A insensitive and did not interact with the calcium pathway. IL-1beta-stimulated GM-CSF mRNA expression and production was strongly dependent on NF-kappaB. IFN-gamma inhibition of the GM-CSF response to IL-1beta acted via NF-kappaB, reducing the translocation of NF-kappaB to the nuclei of RPE cells treated with IL-1beta and IFN-gamma. The results show that IFN-gamma down-regulation acts either directly on NF-kappaB or its activation or by blockade of a pathway upstream of NF-kappaB. However, any such blockade does not involve PKC or intracellular calcium.

Blockade of collagen-induced arthritis post-onset by antibody to granulocyte-macrophage colony-stimulating factor (GM-CSF): requirement for GM-CSF in the effector phase of disease

There is mounting evidence for a role of the growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF) in inflammatory disease, including arthritis. In the present study, we examined the effectiveness of treatment of collagen-induced arthritis (CIA) with a neutralizing mAb to GM-CSF. DBA/1 mice were immunized for the development of CIA and treated at different times, and with different doses, with neutralizing mAb to GM-CSF or isotype control mAb. Anti-GM-CSF mAb treatment prior to the onset of arthritis, at the time of antigen challenge, was effective at ameliorating the ensuing disease. Modulation of arthritis was seen predominantly as a reduction in overall disease severity, both in terms of the number of limbs affected per mouse and the clinical score of affected limbs. Importantly, anti-GM-CSF mAb treatment ameliorated existing disease, seen both as a reduction in the number of initially affected limbs progressing and lower numbers of additional limbs becoming affected. By histology, both inflammation and cartilage destruction were reduced in anti-GM-CSF-treated mice, and the levels of tumor necrosis factor-a and IL-1beta were also reduced in joint tissue washouts of these mice. Neither humoral nor cellular immunity to type II collagen, however, was affected by anti-GM-CSF mAb treatment. These results suggest that the major effect of GM-CSF in CIA is on mediating the effector phase of the inflammatory reaction to type II collagen. The results also highlight the essential role of GM-CSF in the ongoing development of inflammation and arthritis in CIA, with possible therapeutic implications for rheumatoid arthritis.

Dependence of interleukin-1-induced arthritis on granulocyte-macrophage colony-stimulating factor

OBJECTIVE

To determine whether granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage CSF (M-CSF or CSF-1) are involved in the methylated bovine serum albumin/interleukin-1 (mBSA/IL-1)-induced arthritis model.

METHODS

Following systemic injection, IL-1 has been shown to augment a weak inflammatory response to mBSA in murine joints and to induce an acute erosive arthritis. GM-CSF and M-CSF have been implicated in inflammatory reactions, including those in joints, and have recently been shown to exacerbate murine arthritis. Since in vitro studies have found that IL-1 can enhance GM-CSF and M-CSF production, we reasoned that they might be playing a part in IL-1-mediated arthritis. GM-CSF-deficient (GM-CSF-/-) and M-CSF-deficient (op/op) mice were injected intraarticularly with mBSA and subcutaneously with IL-1. Arthritis was monitored histologically on day 7. Normal mice were also treated intraperitoneally with blocking monoclonal antibodies to GM-CSF and M-CSF, and to the M-CSF receptor. Numbers of macrophages (Mac-2 and F4/80 staining) were monitored, as was the number of cycling (bromodeoxyuridine-positive) cells.

RESULTS

GM-CSF-/- mice and normal mice treated with anti-GM-CSF antibody did not show IL-1-induced arthritis progression. There was a dramatic reduction in synovial cellularity, including reduced numbers of macrophages and cycling cells. The op/op mice did not develop mBSA/IL-1-induced disease, but blocking antibody to M-CSF or to the M-CSF receptor failed to diminish disease in normal mice.

CONCLUSION

GM-CSF is involved in the IL-1-induced arthritis that follows mBSA injection; M-CSF involvement in the model is also suggested, since op/op mice did not develop arthritis. These studies provide the first in vivo evidence for a role of GM-CSF, and possibly M-CSF, in the proinflammatory actions of IL-1.

Sex hormone adjuvant therapy in rheumatoid arthritis

RA is an autoimmune rheumatic disorder resulting from the combination of several predisposing factors, including the relation between epitopes of possible triggering agents and histocompatibility epitopes, the status of the stress response system, and the sex hormone status. Estrogens are implicated as enhancers of humoral immunity, and androgens and progesterone are natural immune suppressors. Sex hormone concentrations have been evaluated in RA patients before glucocorticoid therapy and have frequently been found to be altered, especially in premenopausal women and male patients. In particular, low levels of gonadal and adrenal androgens (testosterone and DHT, DHEA and DHEAS) and a reduced androgen:estrogen ratio have been detected in body fluids (i.e., blood, synovial fluid, smears, saliva) of male and female RA patients. These observations support a possible pathogenic role for the decreased levels of the immune-suppressive androgens. Exposure to environmental estrogens (estrogenic xenobiotics), genetic polymorphisms of genes coding for hormone metabolic enzymes or receptors, and gonadal disturbances related to stress system activation (hypothalamic-pituitary-adrenocortical axis) and physiologic hormonal perturbations such as during aging, the menstrual cycle, pregnancy, the postpartum period, and menopause may interfere with the androgen:estrogen ratio. Sex hormones might exert their immune-modulating effects, at least in RA synovitis, because synovial macrophages, monocytes, and lymphocytes possess functional androgen and estrogen receptors and may metabolize gonadal hormones. The molecular basis for sex hormone adjuvant therapy in RA is thus experimentally substantiated. By considering the well-demonstrated immune-suppressive activities exerted by androgens, male hormones and their derivatives seem to be the most promising therapeutic approach. Recent studies have shown positive effects of androgen replacement therapy at least in male RA patients, particularly as adjuvant treatment. Interestingly, the increase in serum androgen metabolism induced by RA treatment with CSA should be regarded as a possible marker of androgen-mediated immune-suppressive activities exerted by CSA, at least in RA and at the level of sensitive target cells and tissues (i.e., synovial macrophages). The absence of altered serum levels of estrogens in RA patients and the reported immune-enhancing properties exerted by female hormones have represented a poor stimulus to test estrogen replacement therapy in RA. The different results obtained with OC use seem to depend on dose-related effects and the different type of response to estrogens in relation to the cytokine balance between Th1 cells (cellular immunity, i.e., RA) and Th2 cells (humoral immunity, i.e., SLE). The androgen replacement obtained directly (i.e., testosterone, DHT, DHEAS) or indirectly (i.e., antiestrogens) may represent a valuable concomitant or adjuvant treatment to be associated with other disease-modifying antirheumatic drugs (i.e., MTX, CSA) in the management of RA.

TNF-alpha is a potent inducer for IFN-inducible protein-10 in hepatocytes and unaffected by GM-CSF in vivo, in contrast to IL-1beta and IFN-gamma

We have recently shown that IFN-inducible protein 10 (IP-10), a member of the CXC chemokine family, is induced in hepatocytes surrounded by infiltrative mononuclear cells in human livers with chronic hepatitis. Hence, we examined the kinds of stimuli that can induce IP-10 expression in hepatocytes in vivo. While the liver expressed three chemokine genes (IP-10, JE/MCP-1, KC/GRO) in a tissue-specific fashion following systemic treatment with pro-inflammatory cytokines, IP-10 mRNA expression showed the most marked liver-specificity. Pretreatment with GM-CSF selectively inhibited IL-1beta, but not TNF-alpha-induced IP-10 mRNA expression. In situ hybridization analysis in the liver and Northern hybridization analysis in isolated liver cell fractions from rodents treated with pro-inflammatory cytokines revealed cellular sources of chemokine expression. IP-10 mRNA expression in hepatocytes was induced by i.v. administration of TNF-alpha, and to a much lesser extent in response to IL-1beta and IFN-gamma, whereas Kupffer cells and endothelial cells expressed IP-10 mRNA equivalently in response to these three stimuli. On the other hand, JE/MCP-1 mRNA expression was detected only in non-parenchymal cells in response to TNF-alpha and IL-1beta, but not in response to IFN-gamma. KC/GRO mRNA expression was also induced mainly in sinusoidal cells by treatment with TNF-alpha or IL-1beta, although it was detected to a lesser extent in hepatocytes. Our results demonstrated that chemokine induction is stimulus-, tissue- and cell type-specific and that IP-10 (but not MCP-1) is inducible in hepatocytes by TNF-alpha most potently, even in the presence of GM-CSF, suggesting the specific role of TNF-alpha-induced IP-10 on intralobular mononuclear infiltration in chronic hepatitis.

Interindividual and intra-articular variation of proinflammatory cytokines in patients with rheumatoid arthritis: potential implications for treatment

OBJECTIVES

Assessment of the numbers and spatial distribution of cells producing interleukin 1alpha (IL1alpha), interleukin 1beta (IL1beta), tumour necrosis factor alpha (TNFalpha), and interleukin 6 (IL6) in the synovial membranes of patients with rheumatoid arthritis (RA).

METHODS

Synovial tissue specimens from 40 patients with RA and eight patients with non-rheumatic disease were obtained by arthroscopy guided biopsy techniques or during joint surgery. A modified immunohistochemical method detecting cytokine producing rather than cytokine binding cells was applied to determine cytokine synthesis in fixed cryopreserved sections. Computerised image analysis methods provided comparative quantitative assessments.

RESULTS

A wide variation between subjects was recorded for both quantities and profiles of expressed cytokines, despite similar macroscopic and histopathological features of inflammation. IL1alpha and IL1beta were the most abundant monokines identified, though produced at different sites. IL1alpha was predominantly seen in vascular endothelial cells, whereas IL1beta staining was mainly shown in macrophages and fibroblasts. Concordant results for the detection of TNFalpha at protein and mRNA levels were obtained with an unexpectedly low number of TNFalpha producing cells compared with IL1 expressing cells in many patients with RA. Specimens acquired arthroscopically from areas with maximum signs of macroscopic inflammation showed an increased number of TNFalpha producing cells in pannus tissue compared with that occurring in synovial villi of a given joint. This clustered distribution was not found for cells expressing any of the other studied cytokines.

CONCLUSION

The recorded heterogeneous profile of proinflammatory cytokine synthesis in the synovial membrane among patients with RA may provide a clue for an understanding of the wide variation in responsiveness to different modes of antirheumatic treatment between patients.

Exacerbation of acute inflammatory arthritis by the colony-stimulating factors CSF-1 and granulocyte macrophage (GM)-CSF: evidence of macrophage infiltration and local proliferation

CSF-1 and GM-CSF have been implicated in the pathogenesis of rheumatoid arthritis. We report the effects of CSF-1 and GM-CSF in the development of an acute methylated bovine serum albumin (mBSA)-induced murine arthritis model. Examination of histopathological features revealed that the systemic administration of CSF-1 or GM-CSF following mBSA administration into the knee resulted in the exacerbation of arthritis. This included synovial hyperplasia and joint inflammation, most evident at 7 and 14 days post-mBSA administration, and the appearance of erosive pannus tissue. The exacerbation by CSF-1 and GM-CSF was not sustained but declined in incidence and severity by 21 days post-mBSA administration, similar to the effects of IL-1beta in this model, reported here and previously. Macrophages expressing Mac-2 and F4/80 were a prominent feature of the pathology observed, particularly the infiltration of Mac-2+ macrophages seen in all mice administered CSF-1, GM-CSF or IL-1beta. Present in inflamed knees was a locally dividing population of cells which included Mac-2+ and F4/80+ macrophages. These studies demonstrate that CSF-1 and GM-CSF can exacerbate and prolong the histopathology of acute inflammatory arthritis and lend support to monocytes/macrophages being a driving influence in the pathogenesis of inflammatory arthritis.

Enhancement of monocyte transendothelial migration by granulocyte-macrophage colony-stimulating factor: requirement for chemoattractant and CD11a/CD18 mechanisms

Granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances and primes monocyte functions, but its role in monocyte migration is poorly understood. We examined monocyte migration across human umbilical vein endothelial cells (HUVEC) grown on filters. GM-CSF had no chemotactic or chemokinetic effect. However, GM-CSF enhanced monocyte transendothelial migration (TEM) through unstimulated and IL-1-activated (5 h) HUVEC in response to C5a or monocyte chemoattractant protein-1 in a dose-dependent fashion, increasing the migration from 28.7 +/- 5.3% to 41.8 +/- 6.2% (n = 8, p < 0.05) and from 34.8 +/- 6% to 50.3 +/- 3.1%, p < 0.05), respectively. The enhanced TEM was inhibited by monoclonal antibodies (mAb) to LFA-1, but not by mAb to Mac-1 or to VLA-4. Furthermore, GM-CSF up-regulated and activated LFA-1, as assessed by NKI-L16 neoepitope expression. The results indicate that: (1) GM-CSF can prime monocytes for increased TEM, (2) GM-CSF enhances LFA-1-mediated monocyte TEM and (3) this effect is in part mediated by increasing LFA-1 expression and activation. Thus, increased GM-CSF production may promote monocyte accumulation in inflammation not only by inducing monocytosis, but also enhancing migration.

Granulocyte-macrophage colony-stimulating factor activity in cerebrospinal fluid

OBJECTIVES

The purpose of this study was to analyse the presence of the granulocyte-macrophage colony-stimulating factor (GM-CSF) in human cerebrospinal fluid (SF) of patients affected by multiple sclerosis (MS) in comparison with non-inflammatory neurological diseases.

MATERIAL AND METHODS

All SFs were collected from 59 patients for diagnostic purpose. The presence of GM-CSF was revealed by measuring its activity and by immunoassay. The data obtained were statistically evaluated.

RESULTS

We found that GM-CSF is constitutively present in human SF; this presence was confirmed by its stimulating activity of colony-forming-unit granulocyte-macrophage (CFU-GM) production. No significant changes of the GM-CSF concentration in the SFs were observed among different neurological disorders (degenerative or vascular) and MS.

CONCLUSION

Our data suggest that GM-CSF is a constitutive component of human SF, relatively uninfluenced by the different morbid conditions of the nervous system.

Autoimmunity is a type I interferon-deficiency syndrome corrected by ingested type I IFN via the GALT system

Type I interferons (IFN-alpha/beta), products of the innate immune system, can modulate immune function whereas proinflammatory IFN-gamma (type II IFN), a product of the acquired immune system upregulates inflammation and enhances cell mediated immunity. We have proposed a unifying hypothesis of the origin of autoimmunity as a type I IFN immunodeficiency syndrome involving inadequate regulation of the acquired immune system product IFN-gamma by the IFN-alpha/beta innate immune system. The common theme of ingested type I IFNs in autoimmunity is inhibition of proinflammatory type II IFN systemically or at the target organ. In multiple sclerosis (MS) and insulin-dependent diabetes mellitus (IDDM) at the target organ, and in rheumatoid arthritis (RA) as a regulator of other proinflammatory cytokines, IFN-gamma is the nexus of inflammation in autoimmunity. Ingested type I IFNs counteract type II IFN, overcome the relative lack of type I IFN activity, and ameliorate autoimmunity. The administration of type I IFNs (IFN-alpha/beta) via the gut offers an exciting alternative to systemic application for overcoming the type I IFN immunodeficiency in autoimmunity. Successful use of ingested type I IFN in three separate prototypical autoimmune diseases suggests a broad antiinflammatory therapeutic profile for this technology.

Inhibitory effect of a new anti-rheumatic drug T-614 on costimulatory molecule expression, cytokine production, and antigen presentation by synovial cells

The present study was undertaken to investigate the immunoregulatory effects of T-614 (3-formylamino-7-methylsulfonylamino-6-phenoxy-4H-1-benzopyran-4-o ne) on synovial cells in vitro. Synovial cells were cultured with T-614 in the presence or absence of various cytokines. After incubation, the costimulatory molecule expression on synovial cells and cytokine production in culture supernatants were analyzed by an indirect immunofluorescence method and enzyme-linked immunosorbent assay, respectively. We also examined the effect of T-614 on the function of synovial cells as antigen-presenting cells (APCs). The costimulatory molecules including CD54, CD58, and CD106 were constitutionally expressed on the surface of synovial cells. However, neither CD80 nor CD86 nor CD102 was found on the surface, and these costimulatory molecules could not be induced by any cytokines. T-614 itself did not affect the costimulatory molecule expression and cytokine production of unstimulated synovial cells. The stimulation of synovial cells with interferon-gamma (IFN-gamma), interleukin-1beta, or 12-O-tetradecanoyl phorbol 13-acetate enhanced the expression of costimulatory molecules and the proinflammatory cytokine production of these cells. Both the up-regulated expression of these costimulatory molecules and the enhanced production of proinflammatory cytokines were significantly inhibited by T-614. Autologous T cell proliferation in response to purified protein derivative by IFN-gamma-treated synovial cells was significantly suppressed by T-614. T-614 has considerable immunosuppressive effects on synovial cells by inhibiting the costimulatory molecule expression and cytokine production of these cells and the antigen-specific T cell proliferation mediated by the synovial cells. These results suggest that T-614 plays an important immunoregulatory role in rheumatoid synovial tissues.

The participation of IL-8 in the synovial lesions at an early stage of rheumatoid arthritis

Synovial tissues from Rheumatoid Arthritis (RA) were divided into three groups based on their histopathological findings and compared for their expression of IL-8 and monocyte chemotactic and activating factor (MCAF) by using immunohistochemistry and in situ hybridization. The levels of IL-8 as well as those of MCAF were markedly higher in the synovial fluid from RA joints. Synovial lining cells (SLC) and macrophages had an ability to produce IL-8 at an early phase of the disease. The presence of MCAF was restricted in macrophages at this stage. On the other hand, the production of IL-8 as well as MCAF were prominent in most components of the joints such as SLC, migrated monocytes, sublining fibroblastoid cells, endothelial cells or migrated neutrophils at an active phase. The expression of IL-8 or MCAF was low in fibrotic synovitis of RA. These data indicate that IL-8 generated from SLC and macrophages may participate to the inflammatory process in the early synovitis of RA.

Oncostatin M: development of a pleiotropic cytokine

Oncostatin M (OM) is a member of the interleukin-6 (IL-6) cytokine subfamily. The binding of OM to its receptor initiates signal transduction through JAK-signal transducers and activators of transcription (STAT) pathways and activates transcription activators through mitogen-activated protein (MAP) kinases. Results of in vitro assays documented that OM modulates cytokine expression and alters the production of proteases that down-regulate inflammation. Administration of OM to lipopolysaccharide (LPS)-challenged mice lowered serum tumor necrosis factor-alpha (TNF-alpha) levels and decreased the lethal effects of LPS administration. OM also reduced inflammation in animal models of human disease, including inflammatory bowel disease, antibody-induced arthritis, and experimental autoimmune encephalomyelitis. Preclinical safety studies have been conducted in the mouse and monkey. Mice were administered OM (subcutaneously) at 72, 360, or 1,560 micrograms/kg/day in a 2-wk toxicity study. Decreased body weights occurred at 1,560 micrograms/kg. Drug-related changes at 360 and 1,560 micrograms/kg consisted of dermal irritation at the injection site, leukopenia, and thymic lymphoid depletion; all changes were reversible following a 2-wk recovery period. In a 2-wk subcutaneous study in monkeys, OM was administered at 1, 5, 15, 45, or 150 micrograms/kg/day. At all doses there was reversible, transient inappetence and dermal irritation at the injection site. Drug-related changes at 5, 15, 45, and 150 micrograms/kg consisted of reversible elevations in both serum amyloid A and IL-6, and reversible thymic lymphoid depletion. Transient increases in body temperature occurred at 15, 45, and 150 micrograms/kg. The observed spectrum of immunomodulatory effects suggests that OM may have therapeutic utility in treating chronic inflammatory diseases.

Cytokine regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) production by human retinal pigment epithelial cells

GM-CSF is an important regulator of macrophage, granulocyte and dendritic cell behaviour and function. These cell types have been implicated in the retinal damage characteristic of endogenous posterior uveitis. Dendritic cells in the choroid have access to retinal antigens processed by the retinal pigment epithelial (RPE) cells of the blood-retinal barrier and are thought to be candidates for the presentation of antigen in uveoretinitis. We therefore investigated the production of GM-CSF and its regulation in human RPE cells. IL-1beta, tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) all stimulated GM-CSF production by RPE cells and a combination of these cytokines increased GM-CSF production over five-fold compared with that with the individual cytokines alone. Interferon-gamma (IFN-gamma) rapidly down-regulated these responses. IFN-gamma did not appear to be acting directly on IL-1beta or via the synthesis of another protein. GM-CSF mRNA expression showed the same pattern of response to these cytokines, indicating transcriptional or pre-transcriptional regulation, and there was no evidence that IFN-gamma was acting by destabilizing GM-CSF mRNA. These results are generally important in understanding the ways in which cytokine regulation differs between different cell types and also more specifically for determining ways in which a cytokine with a significant role in the development of autoimmune uveoretinitis may be manipulated.

Oxidized LDL can induce macrophage survival, DNA synthesis, and enhanced proliferative response to CSF-1 and GM-CSF

Modification of low density lipoprotein (LDL), eg, by oxidation, has been proposed as being important for the formation of foam cells and therefore for the development of atherosclerotic plaques. There are a number of reports showing that macrophage-derived foam cells can proliferate in both human and animal lesions, particularly in the early phase of the disease and possibly involving macrophage-colony stimulating factor (M-CSF, or CSF-1). We studied the in vitro effects of oxidized LDL (ox-LDL) on murine bone marrow-derived macrophages (BMMs), a cell population with a high proliferative capacity in vitro in response to CSF-1 and a dependence for survival on the presence of this growth factor. We report here that treatment of BMMs with low doses of ox-LDL, but not with native LDL, led to cell survival, DNA synthesis, and an enhanced response to the proliferative actions of CSF-1 and granulocyte macrophage-CSF (GM-CSF); the effects were dependent on the degree of LDL oxidation. For CSF-1, a synergistic effect was noticeable at suboptimal doses. The effect of ox-LDL occurred even in the absence of endogenous CSF-1 or GM-CSF. Our findings suggest that ox-LDL, and possibly other modified forms of LDL, could maintain macrophage (and foam cell) survival and therefore lengthen their tenure in a plaque; the modified LDL could also cause local macrophage proliferation or "prime" them so that they could proliferate better in response to CSF-1 (and GM-CSF) concentrations that may be present in the atheroma.

MRL/lpr and MRL+/+ Macrophage DNA Synthesis in the Absence and the Presence of Colony-Stimulating Factor-1 and Granulocyte-Macrophage Colony-Stimulating Factor

Macrophage accumulation and proliferation as well as altered macrophage properties have been observed in autoimmune MRL mice. To determine whether there might be innate differences in the proliferative responses, we examined the DNA synthesis responses of peritoneal macrophages and macrophages derived in vitro from bone marrow precursors (bone marrow-derived macrophages (BMM)). Murine peritoneal exudate macrophages normally require the addition of macrophage CSF (CSF-1) to enter cell cycle in vitro. In contrast, we have found that many thioglycollate-induced adherent peritoneal macrophages, but not resident peritoneal macrophages, from both MRL/lpr and MRL+/+ mice atypically underwent DNA synthesis even in the absence of added CSF-1. They also responded very well to granulocyte-macrophage CSF. These findings may help to explain the appearance of increased macrophage numbers in MRL lesions. In contrast to a previous report, it was found that MRL/lpr and MRL+/+ BMM did not have an enhanced response to CSF-1 and that modulation of CSF-1 receptor expression was not more rapid in MRL BMM. We also found no evidence for abnormal CSF-1 internalization and degradation or for the lpr mutation to have any enhanced effect on BMM survival in the absence of CSF-1. TNF-α lowered the DNA synthesis response to CSF-1 of MRL/lpr BMM rather than enhanced it, as has been reported. Our data suggest that the enhanced accumulation of macrophages in the MRL/lpr kidney cannot be explained by a proposed model of enhanced responsiveness of MRL/lpr BMM to CSF-1, including a contribution by TNF-α.

Role of pro-inflammatory cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is well known to be a chronic autoimmune/inflammatory disease which leads to progressive joint damage and destruction. Less well known is the fact that in severe cases of RA, with extra-articular manifestations and multiple joint involvement, there is also a significant reduction in life expectancy [28]. Hence the need for new therapeutic agents. With the cloning of cDNAs encoding cytokines in the early to mid 1980s, it became possible to use new assays to evaluate cytokine expression in the local site of autoimmunity, the rheumatoid synovium. There were two goals. First would understanding cytokine expression help us understand the pathogenesis of RA? Secondly, would it be possible to learn enough about the cytokine network to establish possible therapeutic targets? While a complete understanding of either of these questions remains elusive, here we review the state of knowledge in early 1998, which shows that much progress has been made and that these goals have been partly reached. The clinical benefits of this knowledge are documented elsewhere in this compilation, as is the role of chemokines, anti-inflammatory cytokines and the cytokines involved in neovascularisation.