Substance P enhances cytokine-induced vascular cell adhesion molecule-1 (VCAM-1) expression on cultured rheumatoid fibroblast-like synoviocytes

Vasoactive Intestinal Peptide Receptor, CRTH2, Antagonist Treatment Improves Eosinophil and Mast Cell-Mediated Esophageal Remodeling and Motility Dysfunction in Eosinophilic Esophagitis

BACKGROUND AND AIMS

Ultrasonography has shown that eosinophils accumulate in each segment of the esophageal mucosa in human EoE, ultimately promoting esophageal motility dysfunction; however, no mechanistic evidence explains how or why this accumulation occurs.

METHODS

Quantitative PCR, ELISA, flow cytometry, immunostaining, and immunofluorescence analyses were performed using antibodies specific to the related antigens and receptors.

RESULTS

In deep esophageal biopsies of EoE patients, eosinophils and mast cells accumulate adjacent to nerve cell-derived VIP in each esophageal segment. qRT-PCR analysis revealed five- to sixfold increases in expression levels of VIP, CRTH2, and VAPC2 receptors and proteins in human blood- and tissue-accumulated eosinophils and mast cells. We also observed a significant correlation between mRNA CRTH2 levels and eosinophil- and nerve cell-derived VIPs in human EoE (p < 0.05). We provide evidence that eosinophil and mast cell deficiency following CRTH2 antagonist treatment improves motility dysfunction in a chronic DOX-inducible CC10-IL-13 murine model of experimental EoE.

CONCLUSIONS

CRTH2 antagonist treatment is a novel therapeutic strategy for inflammatory cell-induced esophageal motility dysfunction in IL-13-induced chronic experimental EoE.

Regulation of Carcinogenesis by Sensory Neurons and Neuromediators

Interactions between the immune system and the nervous system are crucial in maintaining homeostasis, and disturbances of these neuro-immune interactions may participate in carcinogenesis and metastasis. Nerve endings have been identified within solid tumors in humans and experimental animals. Although the involvement of the efferent sympathetic and parasympathetic innervation in carcinogenesis has been extensively investigated, the role of the afferent sensory neurons and the neuropeptides in tumor development, growth, and progression is recently appreciated. Similarly, current findings point to the significant role of Schwann cells as part of neuro-immune interactions. Hence, in this review, we mainly focus on local and systemic effects of sensory nerve activity as well as Schwann cells in carcinogenesis and metastasis. Specific denervation of vagal sensory nerve fibers, or vagotomy, in animal models, has been reported to markedly increase lung metastases of breast carcinoma as well as pancreatic and gastric tumor growth, with the formation of liver metastases demonstrating the protective role of vagal sensory fibers against cancer. Clinical studies have revealed that patients with gastric ulcers who have undergone a vagotomy have a greater risk of stomach, colorectal, biliary tract, and lung cancers. Protective effects of vagal activity have also been documented by epidemiological studies demonstrating that high vagal activity predicts longer survival rates in patients with colon, non-small cell lung, prostate, and breast cancers. However, several studies have reported that inhibition of sensory neuronal activity reduces the development of solid tumors, including prostate, gastric, pancreatic, head and neck, cervical, ovarian, and skin cancers. These contradictory findings are likely to be due to the post-nerve injury-induced activation of systemic sensory fibers, the level of aggressiveness of the tumor model used, and the local heterogeneity of sensory fibers. As the aggressiveness of the tumor model and the level of the inflammatory response increase, the protective role of sensory nerve fibers is apparent and might be mostly due to systemic alterations in the neuro-immune response. Hence, more insights into inductive and permissive mechanisms, such as systemic, cellular neuro-immunological mechanisms of carcinogenesis and metastasis formation, are needed to understand the role of sensory neurons in tumor growth and spread.

Substance P, A Promising Therapeutic Target in Musculoskeletal Disorders

A large number of studies have focused on the role of substance P (SP) and the neurokinin-1 receptor (NK1R) in the pathogenesis of a variety of medical conditions. This review provides an overview of the role of the SP-NK1R pathway in the pathogenesis of musculoskeletal disorders and the evidence for its role as a therapeutic target for these disorders, which are major public health problems in most countries. To summarize, the brief involvement of SP may affect tendon healing in an acute injury setting. SP combined with an adequate conjugate can be a regenerative therapeutic option in osteoarthritis. The NK1R antagonist is a promising agent for tendinopathy, rheumatoid arthritis, and osteoarthritis. Research on the SP-NK1R pathway will be helpful for developing novel drugs for osteoporosis.

Critical Neurotransmitters in the Neuroimmune Network

Immune cells rely on cell-cell communication to specify and fine-tune their responses. They express an extensive network of cell communication modes, including a vast repertoire of cell surface and transmembrane receptors and ligands, membrane vesicles, junctions, ligand and voltage-gated ion channels, and transporters. During a crosstalk between the nervous system and the immune system these modes of cellular communication and the downstream signal transduction events are influenced by neurotransmitters present in the local tissue environments in an autocrine or paracrine fashion. Neurotransmitters thus influence innate and adaptive immune responses. In addition, immune cells send signals to the brain through cytokines, and are present in the brain to influence neural responses. Altered communication between the nervous and immune systems is emerging as a common feature in neurodegenerative and immunopathological diseases. Here, we present the mechanistic frameworks of immunostimulatory and immunosuppressive effects critical neurotransmitters - dopamine (3,4-dihydroxyphenethylamine), serotonin (5-hydroxytryptamine), substance P (trifluoroacetate salt powder), and L-glutamate - exert on lymphocytes and non-lymphoid immune cells. Furthermore, we discuss the possible roles neurotransmitter-driven neuroimmune networks play in the pathogenesis of neurodegenerative disorders, autoimmune diseases, cancer, and outline potential clinical implications of balancing neuroimmune crosstalk by therapeutic modulation.

Proximity ligation assay to study protein-protein interactions of proteins on two different cells

Protein-protein interactions (PPI) by homo-, hetero- or oligo-merization in the cellular environment regulate cellular processes. PPI can be inhibited by antibodies, small molecules or peptides, and this inhibition has therapeutic value. A recently developed method, the proximity ligation assay (PLA), provides detection of PPI in the cellular environment. However, most applications using this assay are for proteins expressed in the same cell. We employ PLA for the first time to study PPI of cell surface proteins on two different cells. Inhibition of PPI using a peptide inhibitor is also quantified using this assay; PLA is used to detect PPI of CD2 and CD58 between Jurkat cells (T cells) and human fibroblast-like synoviocyte-rheumatoid arthritis cells that are important in the immune response in the autoimmune disease rheumatoid arthritis. This assay provides direct evidence of inhibition of PPI of two proteins on different cell surfaces.

The dual regulation of substance P-mediated inflammation via human synovial mast cells in rheumatoid arthritis

BACKGROUND

Neural pathways are thought to be directly involved in the pathogenesis of rheumatoid arthritis (RA). Although synovial mast cells (MCs) are activated by substance P (SP), the role of MCs in neural pathways in RA remains unknown. The aims of this study were to investigate 1) whether tachykinins are produced by synovial MCs and whether production differs in RA and osteoarthritis (OA) patients, and 2) what is the responsible receptor for SP in synovial MCs.

METHODS

Synovial tissues were obtained from patients with RA or OA undergoing joint replacement surgery. Cultured synovium-derived MCs were generated by culturing dispersed synovial cells with stem cell factor. SP expression was investigated using immunofluorescence and enzyme immunoassays. Mas-related gene X2 (MrgX2) expression was reduced in human MCs using a lentiviral shRNA silencing technique.

RESULTS

SP expression was localized around the cell membrane in 41% (median) of the MCs in synovium from RA but in only 7% of that from OA, suggesting the activation of MCs. Synovial MCs expressed tachykinin (TAC) 1 mRNA, the expression of which was upregulated by the aggregation of FcɛRI or the addition of aggregated IgG. However, the released SP appeared to be rapidly degraded by MC chymase. Synovial MCs were activated with SP through MrgX2 to release histamine without producing proinflammatory cytokines.

CONCLUSIONS

Activated synovial MCs may rapidly degrade SP, which may downregulate the SP-mediated activation of synoviocytes in RA. On the other hand, SP activates MCs to induce inflammatory mediators, suggesting the dual regulation of SP-mediated inflammation by MCs in RA.

Pathological role of fibroblast-like synoviocytes in charcot neuroarthropathy

This study was designed to characterize the synovium in the joints of Charcot neuroarthropathy (CNA) and investigate the potential role of fibroblast-like synoviocytes (FLS) in the pathology of CNA. Synovial samples were collected from CNA patients (n = 7) and non-CNA patients (n = 7), for control, during orthopaedic procedures and used for histology and isolation of FLS. Histological characterization of synovium included innervation and FLS localization. The isolated FLS from the CNA and non-CNA synovium were cultured, with or without tumor necrosis factor-α (TNF-α), for evaluation of invasiveness, gene expression, and cartilage degradation. Vasoactive intestinal peptide (VIP), a neuropeptide, was supplemented into the co-cultures of FLS and cartilage explants. Compared with the non-CNA synovium, CNA synovium was highly inflammatory, with reduced innervation and intense expression of cadherin-11. The FLS isolated from CNA synovium, particularly when activated with TNF-α, were more invasive, increased the expression of ADAMTS4, IL-6, and RANKL, and depleted proteoglycans from cartilage explants when they were co-cultured. Addition of VIP into the culture medium neutralized the catabolic effect of the CNA FLS on cartilage explants. In conclusion, FLS plays an important role in the pathology of CNA. Therapies targeting synovium and FLS may prevent or treat the joint destruction in CNA.

Substance P and Chronic Pain in Patients with Chronic Inflammation of Connective Tissue

Objective

Evidence suggests that substance P (SP) is involved in chronic joint inflammation, such as the pathogenesis of rheumatoid arthritis and osteoarthritis. The goal of the research was to evaluate the correlation between chronic pain and changes in the SP level in patients with chronic inflammation of the connective tissue.

Methods

Patients with osteoarthritis and rheumatoid arthritis were enrolled in this study. The relationship between chronic pain intensity and the serum SP concentration was evaluated in these groups of patients with osteoarthritis and rheumatoid arthritis.

Results

The results showed a positive correlation between the serum SP concentrations and chronic pain intensity.

Conclusions

1. The SP serum concentration was significantly different between the groups of patients with OA and RA. 2. There was a positive correlation between the serum SP concentration and chronic pain intensity in OA and RA patients.

Increasing substance P levels in serum and synovial tissues from patients with developmental dysplasia of the hip (DDH)

BACKGROUND

The tachykininergic neurotransmitters have been proved to be involved in the inflammatory progress and chronic pain in series of disease. The present study was undertaken to evaluate the levels of substance P (SP) and its receptors NK-1 receptor (NK-1R) in both serum and synovial tissues of hip joint from patients with different stages of DDH, and to detect the possible correlation of serum SP levels with pain sensation and dysfunction of the hip joint.

METHODS

SP levels in serum and synovial tissues from patients with DDH and DDH combined with osteoarthritis (DDH&OA) group were compared through immunohistochemistry (IHC), ELISA, and 2-step acetic acid extraction method respectively. Expression of NK-1R in synovial tissues was compared through IHC, quantitive Real-Time PCR (QRT-PCR) and Western-Blot. The severities of pain sensation and the functional activities of hip joint were assessed by Visual analogue scale (VAS) and Harris hip score (HHS). Correlations of serum SP levels with VAS, HHS and erythrocyte sedimentation rate (ESR) were evaluated respectively in these groups.

RESULTS

Significantly elevated serum SP levels were detected in group of DDH and DDH&OA compared to that in normal group. IHC, QRT-PCR as well as tissue Elisa showed that SP levels in synovial tissue of DDH&OA group is stronger than that in DDH group. Serum SP levels in each group have no gender differences. The enhanced SP levels in synovial tissue mainly came from the segregation of peripheral nerve endings. Serum SP correlated with VAS and HHS in patients with DDH&OA (Male + Female). Serum SP correlated with HHS in patients with DDH (Male). Serum SP levels also correlated with erythrocyte sedimentation rate (ESR) in patients with DDH&OA (Male + Female). Up-regulated expression of NK-1R was also observed in synovial tissue of patients with DDH&OA compared to patients with DDH, through western-blot, IHC, and QRT-PCR.

CONCLUSIONS

These findings indicated that the increasing SP levels in serum and synovial tissues, observed from patients with DDH to patients with DDH&OA, might associate with the loss of function and chronic pain sensation in hip joint. SP along with its receptors NK-1R might be involved in the progression of DDH into DDH&OA. In the future, inhibitors of SP as well as NK-1R may represent a novel pharmacotherapy target for pain relieving, inflammation alleviating and joint degeneration delaying for patients with DDH.

Brucella abortus invasion of synoviocytes inhibits apoptosis and induces bone resorption through RANKL expression

Arthritis is one of the most common complications of human active brucellosis, but its pathogenic mechanisms have not been completely elucidated. In this paper, we describe the role of synoviocytes in the pathogenesis of brucellar arthritis. Our results indicate that Brucella abortus infection inhibited synoviocyte apoptosis through the upregulation of antiapoptotic factors (cIAP-2, clusterin, livin, and P21/CIP/CDNK1A). In contrast, infection did not change the expression of proteins that have been involved in apoptosis induction such as Bad, Bax, cleaved procaspase 3, CytC, and TRAIL, among others; or their expression was reduced, as occurs in the case of P-p53(S15). In addition, B. abortus infection induced upregulation of adhesion molecules (CD54 and CD106), and the adhesion of monocytes and neutrophils to infected synoviocytes was significantly higher than to uninfected cells. Despite this increased adhesion, B. abortus-infected synoviocytes were able to inhibit apoptosis induced by supernatants from B. abortus-infected monocytes and neutrophils. Moreover, B. abortus infection increased soluble and membrane RANKL expression in synoviocytes that further induced monocytes to undergo osteoclastogenesis. The results presented here shed light on how the interactions of B. abortus with synovial fibroblasts may have an important role in the pathogenesis of brucellar arthritis.

Altered in vitro immune response to hypoxia-treated normal peritoneal fibroblasts

Hypoxia treatment of normal peritoneal fibroblasts results in alterations that are characteristic for fibroblasts obtained from postoperative peritoneal adhesion tissue. In this study, we have shown that hypoxia treatment enhances normal peritoneal fibroblast elimination by lymphokine-activated killer cells to the level of adhesion tissue fibroblasts, suggesting a pivotal role of hypoxia in the adhesion development.

Substance P receptor mediated maintenance of chronic inflammation in EAE

Substance P (SP) is a modulatory, pro-inflammatory neuropeptide. We investigated the role of the SP receptor, neurokinin-1 (NK-1), in EAE. Our data show that in the chronic phase, mice lacking NK-1 have improved mobility and decreased numbers of LFA-1 high CD4+ T cells and MOG-specific, IFN-gamma producing CD4+ T cells. SR140333, an NK-1 antagonist, administered alone during the chronic phase of EAE was not sufficient to ameliorate symptoms. These results indicate that SP, through NK-1, contributes to maintenance of CNS inflammation, and combining NK-1 antagonists with conventional anti-inflammatory treatments may enhance the success of treatments for diseases like multiple sclerosis.

Synovial biology and T cells in rheumatoid arthritis

Events that occur in rheumatoid arthritis synovial tissues are responsible for the signs and symptoms of joint inflammation and for the eventual destruction of articular and periarticular structures that lead to joint dysfunction and disability. The three most abundant cell populations in RA synovium are synovial macrophages (type A synoviocytes), synovial fibroblasts (type B synoviocytes) and infiltrating T lymphocytes. Other important cell populations include B lymphocytes, dendritic cells, plasma cells, mast cells and osteoclasts. Our current understanding of rheumatoid arthritis is moving beyond previous concepts that view this disease as the consequence of a specific and focused humoral or cellular autoimmune response to a single autoantigen. Rather, a new view of rheumatoid arthritis is emerging, which seeks to understand this disease as the product of pathologic cell-cell interactions occurring within a unique and defined environment, the synovium. T lymphocytes in rheumatoid arthritis synovium interact closely with dendritic cells, the most potent antigen-presenting cell population in the immune system. T cells also interact with monocytes and macrophages and cytokine-activated T cells may be, especially, suited to trigger production of the important cytokine TNFalpha by synovial macrophages. Recent evidence also suggests a potent bidirectional interaction between synovial T cells and synovial fibroblasts, which can lead to activation of both cell types. An important role for synovial B lymphocytes has been emphasized recently, both by experimental data and by results of clinical interventions. B cells in synovium can interact with fibroblasts as well as with other cells of the immune system and their potential role as antigen-presenting cells in the joint is as yet underexplored. Rheumatoid arthritis synovium may be one of the most striking examples of pathologic, organ-specific interactions between immune system cells and resident tissue cell populations. This view of rheumatoid arthritis also leads to the prediction that novel approaches to treatment will more logically target the intercellular communication systems that maintain such interactions, rather than attempt to ablate a single cell population.

Dipeptidyl peptidase IV activity and/or structure homologs: contributing factors in the pathogenesis of rheumatoid arthritis?

Several of the proinflammatory peptides involved in rheumatoid arthritis pathogenesis, including peptides induced downstream of tumor necrosis factor-α as well as the monocyte/T cell-attracting chemokines RANTES and stromal cell-derived factor (SDF)-1α and the neuropeptides vasoactive intestinal peptide (VIP) and substance P, have their biological half-lives controlled by dipeptidyl peptidase IV (DPPIV). Proteolysis by DPPIV regulates not only the half-life but also receptor preference and downstream signaling. In this article, we examine the role of DPPIV homologs, including CD26, the canonical DPPIV, and their substrates in the pathogenesis of rheumatoid arthritis. The differing specific activities of the DPPIV family members and their differential inhibitor response provide new insights into therapeutic design.

Role of Transient Receptor Potential Vanilloid 1 Receptors in Adjuvant-Induced Chronic Arthritis: In Vivo Study Using Gene-Deficient Mice

The transient receptor potential vanilloid 1 (TRPV1) receptor is a nonselective cation channel localized on a subset of primary sensory neurons and can be activated by a wide range of stimuli. The present study investigated the role of this receptor in chronic arthritis evoked by complete Freund's adjuvant (CFA) using TRPV1 receptor gene-deleted (TRPV1-/-) mice and wild-type counterparts (TRPV1+/+). In TRPV1+/+ mice, CFA injected intraplantarly into the left hindpaw and the root of the tail induced swelling of the injected and contralateral paws up to 130 and 28%, respectively, measured by plethysmometry throughout 18 days. Mechanonociceptive threshold measured with dynamic plantar aesthesiometry was decreased by 50 and 18% on the injected and contralateral paws, respectively. Histological examination and scoring of the tibiotarsal joints revealed marked arthritic changes in wild-type mice. In TRPV1-/- animals edema, histological score and mechanical allodynia were significantly smaller. Daily treatment with the lipoxygenase inhibitor nordihydroguaretic acid (NDGA), the cyclooxygenase inhibitor indomethacin, the bradykinin B2 receptor antagonist HOE-140 [D-arginyl-L-arginyl-L-prolyl-trans-4-hydroxy-L-prolylglycyl-3-(2-thyenyl)-L-alanyl-L-seryl-D-1,2,2,4-tetrahydro-3-isoquinolinecarbonyl-L-(2a,3b,7ab)-octahydro-1H-indole-2-carbonyl-L-arginine], or the B1 receptor antagonist desArgHOE-140 [D-arginyl-L-arginyl-L-prolyl-trans-4-hydroxy-L-prolylglycyl-3-(2-thyenyl)-L-alanyl-L-seryl-D-1,2,2,4-tetrahydro-3-isoquinolinecarbonyl-L-(2a,3b,7ab)-octahydro-1H-indole-2-carbonyl] was performed to reveal what mediators might activate TRPV1. NDGA significantly inhibited edema, hyperalgesia, and arthritis score in TRPV1+/+, but not in TRPV1-/- mice. The effect of indomethacin was markedly smaller in knockouts. In TRPV1+/+ animals, HOE-140, but not desArgHOE-140, inhibited arthritis, whereas in TRPV1-/- mice, HOE-140 produced limited effect. Thus, whereas bradykinin and lipoxygenase products seem to act exclusively via TRPV1 activation, prostanoids do not, or at least only partially, to enhance murine experimental arthritis and related hyperalgesia.

Involvement of steroids in anti-inflammatory effects of PK11195 in a murine model of pleurisy

BACKGROUND

Studies on peripheral benzodiazepine receptor function have yielded a diverse list of activities of which the anti-inflammatory effects need to be further examined.

AIMS

To evaluate the role of steroids, nitric oxide and adenosine-deaminase in the anti-inflammatory effect of PK11195.

METHODS

Pleurisy was induced by intrapleural injection of carrageenan in mice pre-treated or not with PK11195. Leukocytes, exudation, adenosine-deaminase (ADA) activity and nitric oxide (NO) level were measured. Steroid involvement was evaluated by pre-treatment with D,L-aminogluthetimide before PK11195.

RESULTS

Leukocytes, exudation and NO levels were reduced by PK11195 in the early (4 h) phase. In the late (48 h) phase, PK11195 decreased leukocytes and ADA activity. D,L-aminogluthetimide reversed the effect of PK11195 on exudate (4 h), as well as total and differential leukocytes and NO levels (48 h).

CONCLUSIONS

Steroids, NO and ADA are implicated in the anti-inflammatory action of PK11195.

Neurogenic Aspects of Inflammation

The relationship between the inflammatory process and the nervous system is twofold. The nervous system is activated by inflammation which causes inflammatory pain and impaired motor function. Conversely, the nervous system acts back on the peripheral process. This is achieved by output systems at different levels, including primary afferent fibers (neurogenic inflammation), spinal cord (reflexes), and the brain (eg, neuroendocrine functions). This article first addresses the activation of the nociceptive system by inflammation; the second part describes the effects of the nervous system on inflamed tissue.

Fibroblast-Like Synoviocytes of Mesenchymal Origin Express Functional B Cell-Activating Factor of the TNF Family in Response to Proinflammatory Cytokines

Immunohistochemical analysis revealed that the intimal lining cells of synovial tissue of inflamed joints of patients with rheumatoid arthritis differed from that of normal joints or of diseased joints in osteoarthritis in that they stained with mAb specific for the B cell-activating factor of the TNF family (BAFF; also called BLyS). We generated fibroblast-like synoviocytes (FLS) cell lines that were bereft of myelomonocytic cells to examine whether mesenchymal-derived FLS could express this critical B cell survival factor. We found that FLS expressed low amounts of BAFF mRNA relative to that of myelomonocytic cells. However, when various cytokines/factors were added to such FLS cell lines, we found that IFN-gamma or TNF-alpha were unique in that they could induce significant increases in BAFF mRNA and protein. Even minute amounts of IFN-gamma primed FLS for TNF-alpha, allowing the latter to stimulate significantly higher levels of BAFF mRNA and protein than could TNF-alpha alone. Consistent with this, B cells cocultured with IFN-gamma and/or TNF-alpha-treated FLS had a significantly greater viability than B cells cocultured with nontreated FLS. The enhanced protection of B cells afforded by IFN-gamma/TNF-alpha-treated FLS was inhibited by the addition of BAFF-R:Fc fusion protein. We conclude that the proinflammatory cytokines IFN-gamma and TNF-alpha can induce mesenchymal-derived FLS to express functional BAFF in vitro. The induced expression of BAFF on FLS by proinflammatory cytokines may enhance the capacity of such cells to protect B cells from apoptosis in inflammatory microenvironments in vivo.

A role for substance P in arthritis?

Substance P is a neuropeptide that is released from sensory nerves and which has a number of pro-inflammatory effects. In this article, we review the evidence for a role of substance P in arthritis, both in experimental animal models and rheumatoid arthritis patients. Substance P expression is altered in the joint and dorsal horn of arthritic animals, exogenous substance P and neurokinin 1 (NK(1)) receptor antagonists modulate responses in the joint, and there is some evidence for a role of substance P in human joint disease. However, the therapeutic potential of NK(1) receptor antagonists in the treatment of rheumatoid arthritis remains controversial.

Experimental neurogenic cystitis

Recent advances in basic and clinical research indicate that interstitial cystitis (IC) is a form of neurogenic inflammation, thereby opening new avenues for research into this painful disease. With this in mind, we have recently developed a rat model of neurogenic inflammation of the bladder produced by a central nervous system viral disease. As in IC, the inflammation in this model develops without direct injury or trauma to the bladder, is non-infectious, and is limited to the bladder. Our most recent studies aimed at further testing the similarity of this animal model to IC by assessing the urine content in histamine with the occurrence of mast cell degranulation in the bladder wall. We further verified for a sex difference in the occurrence of the disease. Our results showed increased levels of urine histamine and mast cell activation during the early stages of the disease. We additionally observed that females had a greater degree of plasma extravasation, while males had a greater cellular infiltration together with worse behavioral signs. Gonadectomy prevented the bladder inflammation altogether in both males and females. These findings further validate our model of neurogenic cystitis to study the neurogenic component of IC.

Substance P receptor expression on lymphocytes is associated with the immune response to respiratory syncytial virus infection

The kinetics and magnitude of SP receptor expression was determined for bronchoalveolar leukocyte cell subsets from BALB/c mice in the primary immune response to respiratory syncytial virus (RSV) and human parainfluenza virus-3 (PIV3) infection, and in the secondary immune response to RSV and PIV3 challenge. In both the primary and secondary responses to infection, expression of substance P (SP) receptors was markedly increased by infection, especially for T lymphocytes, compared to B220+, CD11b+ and CD14+ cells. CD4+ T lymphocytes predominantly expressed SP receptors in the secondary response. These results suggest that SP receptor expression may be important in the development of primary and secondary immune responses to respiratory virus infections.

Neutralizing anti-F glycoprotein and anti-substance P antibody treatment effectively reduces infection and inflammation associated with respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the most important virus mediating lower respiratory tract illness in infants and young children. RSV infection is associated with pulmonary inflammation and increased levels of substance P (SP), making the airways and leukocytes that express SP receptors susceptible to the proinflammatory effects of this peptide. This study examines combining neutralizing anti-F glycoprotein and anti-SP antibody treatment of RSV-infected BALB/c mice to inhibit RSV replication and inflammation associated with infection. BALB/c mice were prophylactically treated with antibody prior to RSV infection or were therapeutically treated at day 2 or 6 post-RSV infection. Prophylactic or therapeutic treatment with anti-SP antibodies promptly reduced pulmonary inflammatory cell infiltration and decreased the number of cells expressing proinflammatory cytokines, while anti-F antibody treatment reduced virus titers. The results suggest that combined anti-viral and anti-SP antibody treatment may be effective in treating RSV disease.

Defective gp130-mediated signal transducer and activator of transcription (STAT) signaling results in degenerative joint disease, gastrointestinal ulceration, and failure of uterine implantation

The receptor subunit gp130 transduces multiple cell type-specific activities of the leukemia inhibitory factor (LIF)/interleukin (IL)-6 family of cytokines through the signal transducer and activator of transcription (STAT) and src homology 2 domain-bearing protein tyrosine phosphatase (SHP)-2/ras/Erk pathways. To define STAT-dependent physiological responses, we generated mice with a COOH-terminal gp130(DeltaSTAT) "knock-in" mutation which deleted all STAT-binding sites. gp130(DeltaSTAT) mice phenocopyed mice deficient for IL-6 (impaired humoral and mucosal immune and hepatic acute phase responses) and LIF (failure of blastocyst implantation). However, unlike mice with null mutations in any of the components in the gp130 signaling pathway, gp130(DeltaSTAT) mice also displayed gastrointestinal ulceration and a severe joint disease with features of chronic synovitis, cartilaginous metaplasia, and degradation of the articular cartilage. Mitogenic hyperresponsiveness of synovial cells to the LIF/IL-6 family of cyto-kines was caused by sustained gp130-mediated SHP-2/ras/Erk activation due to impaired STAT-mediated induction of suppressor of cytokine signaling (SOCS) proteins which normally limits gp130 signaling. Therefore, the joint pathology in gp130(DeltaSTAT) mice is likely to arise from the disturbance of the otherwise balanced activation of the SHP-2/ras/Erk and STAT signaling cascades emanating from gp130.

Anti-inflammatory effects of peripheral benzodiazepine receptor ligands in two mouse models of inflammation

In vivo treatment of mice with peripheral benzodiazepine receptor ligands exerts an inhibitory effect on the inflammatory response in two models of acute inflammation. In the first model, pretreatment of the animals (24 h) with 1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide (PK11195) and 7-chloro-5-(4-Chlorophenyl)-1, 3-dihydro-1-methyl-2-H-1,4-benzodiazepin-2 (Ro5-4864), at different doses (0.00001-10 mg/kg, i.p.) dose dependently inhibited the formation of mouse paw oedema induced by carrageenan with mean ID(50s) of 0.009 (95% confidence limits=0.0076-0.013) and 0.04 (95% confidence limits=0.025-0.0086) mg/kg, respectively. Both ligands (0. 1 mg/kg, i.p.) inhibited in the same way the mouse paw oedema induced by carrageenan in animals with and without adrenal glands. PK11195 and Ro5-4864 (0.1 mg/kg, i.p.) inhibited the mouse paw oedema induced by several inflammatory mediators. In the second model, the pretreatment (24 h) with peripheral benzodiazepine receptor ligands (0.1 mg/kg, i.p.) exerted an inhibitory effect on neutrophil influx and produce a marked inhibition of carrageenan-produced interleukin-13 and interleukin-6 in pleural exudation. Our results extend previous findings that peripheral benzodiazepine receptor is involved in the inflammatory response, and suggest that this action may be linked to the action of different inflammatory mediators, probably mainly by the inhibition of the release of pro-inflammatory cytokines.

Specific inhibition of glucocorticoid-induced thymocyte apoptosis by substance P

Glucocorticoids (GC) are strong inducers of thymocyte apoptosis. In the present study we looked into the possibility that the neuropeptide substance P (SP) might serve as an antagonist to GC-induced apoptosis. Indeed, SP inhibited hydrocortisone (HC)-induced apoptosis of CD4+CD8+ thymocytes in mice, both in vivo and in vitro. It also inhibited HC-induced apoptosis in the T cell hybridoma line 2B4.11, which is sensitive to GC. The inhibitory effect was complete if SP was given with HC or within 1 h after it; partial inhibitory effect could be seen at 2 h and no effect at 3 h. The presence of the SP antagonist nullified SP effect. The effect was specific to both components of the system (i.e., HC as apoptosis inducer and SP as its inhibitor), as judged from comparison to three other apoptosis-inducing means (irradiation, thymic epithelial cells, or retinoic acid), and to two other neuropeptides (somatostatin and vasoactive intestinal peptide). SP/HC antagonism was further demonstrated in two relevant molecular events: 1) HC augmented GC receptor production in our cell system and this was inhibited by SP; and 2) HC reduced the expression of the transcription factor NF-kappaB, SP increased it and when both were present, SP effect dominated. On the other hand, the level of IkappaB (NF-kappaB inhibitory molecule) was decreased by SP, preserved at a relatively high level with HC, and when both SP and HC were present, SP effect dominated. The intensity of SP effect, both in vivo and in vitro, its specificity, its inhibition by SP antagonist, as well as the previously documented presence of SP and its receptor in the thymus suggest that SP might be a physiological antagonist of the potent thymocyte apoptosis induced by GC.

Respiratory syncytial virus infection and G and/or SH protein expression contribute to substance P, which mediates inflammation and enhanced pulmonary disease in BALB/c mice

A distinct clinical presentation of respiratory syncytial virus (RSV) infection of humans is bronchiolitis, which has clinical features similar to those of asthma. Substance P (SP), a tachykinin neuropeptide, has been associated with neurogenic inflammation and asthma; therefore, we chose to examine SP-induced inflammation with RSV infection. In this study, we examined the production of pulmonary SP associated with RSV infection of BALB/c mice and the effect of anti-SP F(ab)(2) antibodies on the pulmonary inflammatory response. The peak production of pulmonary SP occurred between days 3 and 5 following primary RSV infection and day 1 after secondary infection. Treatment of RSV-infected mice with anti-SP F(ab)(2) antibodies suggested that SP may alter the natural killer cell response to primary and secondary infection. In mice challenged after formalin-inactivated RSV vaccination, SP appears to markedly enhance pulmonary eosinophilia as well as increase polymorphonuclear cell trafficking to the lung. Based on studies with a strain of RSV that lacks the G and SH genes, the SP response to RSV infection appears to be associated with G and/or SH protein expression. These data suggest that SP may be an important contributor to the inflammatory response to RSV infection and that anti-SP F(ab)(2) antibodies might be used to ameliorate RSV-associated disease.

Tachykinin receptor modulators: novel therapeutics for rheumatoid arthritis

The activation of a cellular immune response in a genetically susceptible individual is widely recognised as a main step in triggering rheumatoid arthritis (RA). The tachykinins, substance P (SP) and neurokinin A (NKA), can play a major role in different immune diseases. In patients with inflammatory joint disease, elevated levels of SP have been demonstrated in the synovial fluid of affected joints. It is well known that SP and, to a lesser extent, NKA are deeply involved in the processing of nociceptive signals and exert many pro-inflammatory actions, which may be elicited by an increased neuronal neurokinin release in arthritis; the mechanism behind this increase remains to be fully elucidated. Different observations suggest that one approach to the treatment of RA might be to inhibit the local effects of neurokinins in the affected joints. This review will summarise the more relevant aspects of this topic.

HLA-G in the human thymus: a subpopulation of medullary epithelial but not CD83(+) dendritic cells expresses HLA-G as a membrane-bound and soluble protein

The human MHC class Ib gene HLA-G is transcribed and translated in different placental cell subpopulations during pregnancy. In addition to this restricted tissue distribution, HLA-G proteins were also recently detected in the thymus of HLA-G transgenic mice, as well as in some human thymic epithelial cells (TEC). There was a need to further define the phenotype of the HLA-G-expressing cells in the human thymus as well as the type of translated forms that they produce. Using several HLA-G-specific mAb and immunohistochemistry performed on cryosections of human thymi at different ages, we found that the HLA-G-expressing cells are present on medullary cells exhibiting the epithelial morphological type 6. Co-localization experiments performed by double or triple immunofluorescence staining demonstrate that these HLA-G-expressing cells express various cytokeratins, epithelial cell markers but not the CD83 dendritic cell marker. We further show by ELISA measurements that a subset of primary cultured human TEC also expresses soluble HLA-G. Therefore, HLA-G protein tissue distribution is not restricted solely to placental cells. A subpopulation of medullary TEC also expresses HLA-G both at their cell surface and in secreted form, raising the question of the functional significance of such MHC class Ib molecules. Whether thymic soluble and/or membrane-bound HLA-G contribute to inhibit NK cells or to a negative selection of autoreactive T cells which could be harmful in case of pregnancy and/or to a positive selection of viral peptides/HLA-G-restricted CD8(+) T cells remains to be demonstrated.

Signaling and effector pathways

There is increasing evidence that distinct signaling and effector pathways in the rheumatoid synovium result in a cascade of pathophysiologic events. These interactions, which finally lead to progressive joint destruction, are different from all other joint diseases in numerous aspects. As outlined in this review, molecular biology techniques allow detection of key pathways ranging from external stimuli to subcellular gene regulation mechanisms operative in various cells within the rheumatoid synovium. To alter these pathways, inhibitory factors need to be applied to these "hot zones" for an extended period, which can be achieved either by repeated drug administration or by local synthesis using genetically altered synovial cells. Both adenovirus and retroviral constructs, as well as ex vivo and in vivo strategies, can be used for gene transfer into these cells, and routine delivery of "protective" genes into the affected joints might be achieved within the next decade.