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CD8 T-cell infiltration in extravascular tissues of patients with human immunodeficiency virus infection. Interleukin-15 upmodulates costimulatory pathways involved in the antigen-presenting cells-T-cell interaction.

Interleukin (IL)-15 regulates the proliferative activity of the CD8(+) T-cell pool in human immunodeficiency virus (HIV)-infected patients, thereby contributing to the maintenance of the CD8(+) T-cell-mediated immune response against HIV in extravascular tissues, including the lung. However, the effects of IL-15 on antigen-presenting cells (APC) during HIV infection are still unclear. In this study, we evaluated whether IL-15 regulates the macrophage stimulatory pathways governing inflammatory events that take place in the lung of patients with HIV infection. As a first step we evaluated the in vitro effects of IL-15 on lung macrophages retrieved from the respiratory tract of eight normal subjects. Although macrophages from uninfected individuals expressed the IL-15 binding proteins (IL-15Ralpha and the common gammac) at resting conditions, they did not express IL-15 messenger RNA (mRNA). However, a 24-hour stimulation with IL-15 induced the expression of interferon-gamma (IFN-gamma) and IL-15 itself, suggesting a role for this cytokine in the activation of the pulmonary macrophage pool during inflammation. As a confirmation of the role of IL-15 in this setting, at resting conditions, alveolar macrophages of patients with HIV infection and T-cell alveolitis expressed IL-15, IFN-gamma, and IL-15 binding proteins; showed an upmodulation of costimulatory molecules, B7 and CD72, which are involved in the APC of macrophages; and behaved as effective accessory cells because they elicited a strong proliferation of T cells. The accessory effect was inhibited by pretreatment with anti-CD72, anti-B7 (CD80 and CD86), and anti-IL-15 monoclonal antibodies (MoAb). We then investigated the relationship between IL-15 and the expression of costimulatory molecules by macrophages. A 24-hour stimulation of IL-15Ralpha+/gammac+ macrophages with IL-15 upregulated the expression of CD80 and CD86. The evidence that IL-15 upregulates the expression of coligands that favor the contact between T cells and APC, per se, triggers T-cell activation and proliferation and acts as a chemoattractant for T cells, suggests that IL-15 plays a key role in Tc1-mediated defense mechanisms taking place in extravascular tissues of patients with HIV disease.

Adult↗

The platelet-derived growth factor controls c-myc expression through a JNK- and AP-1-dependent signaling pathway.

Pro-inflammatory cytokines, environmental stresses, as well as receptor tyrosine kinases regulate the activity of JNK. In turn, JNK phosphorylates Jun members of the AP-1 family of transcription factors, thereby controlling processes as different as cell growth, differentiation, and apoptosis. Still, very few targets of the JNK-Jun pathway have been identified. Here we show that JNK is required for the induction of c-myc expression by PDGF. Furthermore, we identify a phylogenetically conserved AP-1-responsive element in the promoter of the c-myc proto-oncogene that recruits in vivo the c-Jun and JunD AP-1 family members and controls the PDGF-dependent transactivation of the c-myc promoter. These findings suggest the existence of a novel biochemical route linking tyrosine kinase receptors, such as those for PDGF, and c-myc expression through JNK activation of AP-1 transcription factors. They also provide a novel potential mechanism by which both JNK and Jun proteins may exert either their proliferative or apoptotic potential by stimulating the expression of the c-myc proto-oncogene.

Animals↗

Effects of nonsteroidal anti-inflammatory drugs on proliferation and on induction of apoptosis in colon cancer cells by a prostaglandin-independent pathway.

Nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of and mortality from colon cancer. We observed that NSAIDs inhibit the proliferation rate, alter the cell cycle distribution, and induce apoptosis in colon cancer cell lines. We evaluated whether the inhibition by NSAIDs of prostaglandin (PG) synthesis is required for their effects on colon cancer cells by studying two human colon cancer cell lines: HCT-15 and HT-29. HCT-15, which lacks cyclooxygenase transcripts, does not produce PGs even when exogenously stimulated, whereas HT-29 produces PGE2, PGF2 alpha, and PGI2. HCT-15 and HT-29 cells, when treated for up to 72 hr with 200 microM sulindac sulfide (an active metabolite of sulindac) or 900 microM piroxicam, showed changes in proliferation, cell cycle phase distribution, and apoptosis. Treatment with PGE2, PGF2 alpha, and PGI2, following a variety of protocols, and at concentrations between 10(-6) and 10(-11) M, failed to reverse the effects of NSAIDs on these three parameters of cell growth. We concluded that NSAIDs inhibit the proliferation rate of the two colon cancer cell lines independent of their ability to inhibit PG synthesis. Thus, alternative mechanisms for their activity on tumor cell growth must be entertained. These observations may be relevant to the mechanism of colon tumor inhibition by NSAIDs.

Anti-Inflammatory Agents, Non-Steroidal↗

Rofecoxib modulates multiple gene expression pathways in a clinical model of acute inflammatory pain.

New insights into the biological properties of cyclooxygenase-2 (COX-2) and its response pathway challenge the hypothesis that COX-2 is simply pro-inflammatory and inhibition of COX-2 solely prevents the development of inflammation and ameliorates inflammatory pain. The present study performed a comprehensive analysis of gene/protein expression induced by a selective inhibitor of COX-2, rofecoxib, compared with a non-selective COX inhibitor, ibuprofen, and placebo in a clinical model of acute inflammatory pain (the surgical extraction of impacted third molars) using microarray analysis followed by quantitative RT-PCR verification and Western blotting. Inhibition of COX-2 modulated gene expression related to inflammation and pain, the arachidonic acid pathway, apoptosis/angiogenesis, cell adhesion and signal transduction. Compared to placebo, rofecoxib treatment increased the gene expression of ANXA3 (annexin 3), SOD2 (superoxide dismutase 2), SOCS3 (suppressor of cytokine signaling 3) and IL1RN (IL1 receptor antagonist) which are associated with inhibition of phospholipase A(2) and suppression of cytokine signaling cascades, respectively. Both rofecoxib and ibuprofen treatment increased the gene expression of the pro-inflammatory mediators, IL6 and CCL2 (chemokine C-C motif ligand 2), following tissue injury compared to the placebo treatment. These results indicate a complex role for COX-2 in the inflammatory cascade in addition to the well-characterized COX-dependent pathway, as multiple pathways are also involved in rofecoxib-induced anti-inflammatory and analgesic effects at the gene expression level. These findings may also suggest an alternative hypothesis for the adverse effects attributed to selective inhibition of COX-2.

Acute Disease↗

Protective effect of sensory denervation in inflammatory arthritis (evidence of regulatory neuroimmune pathways in the arthritic joint).

OBJECTIVE: To investigate the direct effect of joint innervation on immune mediated joint inflammation in a patient with psoriatic arthritis (PsA). CASE REPORT: The patient developed arthritis mutilans in all digits of both hands with the exception of the left 4th finger, which had prior sensory denervation following traumatic nerve dissection. Plain radiography, ultrasonography and nerve conduction studies of the hands confirmed the absence of articular disease and sensory innervation in the left 4th digit. METHODS: This relationship between joint innervation and joint inflammation was investigated experimentally by prior surgical sensory denervation of the medial aspect of the knee in six Wistar rats in which carrageenan induced arthritis was subsequently induced. Prior sensory denervation--with preservation of muscle function--prevented the development of inflammatory arthritis in the denervated knee. DISCUSSION: Observations in human and animal inflammatory arthritis suggest that regulatory neuroimmune pathways in the joint are an important mechanism that modulates the clinical expression of inflammatory arthritis.

Animals↗

A novel diterpenoid labdane from Sideritis javalambrensis inhibits eicosanoid generation from stimulated macrophages but enhances arachidonate release.

The diterpenoid ent-8alpha-hydroxy-labda-13(16),14-dien ("labdane F2") was obtained from an anti-inflammatory extract of Sideritis javalambrensis. Labdane F2 inhibited prostaglandin E2 generation in cultured mouse peritoneal macrophages, treated with zymosan, ionophore A23187, or arachidonic acid itself, and in J774 macrophage-like cells activated by bacterial lipopolysaccharide (LPS). The mechanism was investigated by prelabelling the macrophages with radiolabelled arachidonic acid or oleic acid, followed by cell activation in the presence or absence of nontoxic concentrations of labdane F2. Surprisingly, under those conditions in which reduced PGE2 generation was observed, labdane F2 consistently enhanced the release of labelled fatty acid, in a manner similar to that displayed by thimerosal a known acyl-CoA: lysolecithin transferase inhibitor. Labdane E2 therefore appears to possess 2 mutually opposing actions on the eicosanoid system in macrophages: potentiation of delivery of substrate following cell activation, followed by inhibition of conversion of substrate to product. It was also found that nontoxic concentrations of labdane F2 reduced the expression of the inducible isoforms of cyclooxygenase and nitric oxide synthase in LPS-treated J774 cells. Thus, this anti-inflammatory diterpenoid labdane possesses a diverse array of effects impinging on enzyme pathways involved in eicosanoid generation and other inflammatory pathways in macrophages.

Animals↗

Anti-inflammatory mechanism of alminoprofen: action on the phospholipid metabolism pathway.

Alminoprofen is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylpropionic acid class. It has anti-inflammatory properties different from the classical NSAID. Using both in vitro systems of cells in culture and in vivo models of inflammation, we report here that alminoprofen possesses both antiphospholipase A2 (PLA2) activity and anti-cycloxygenase (COX) activity. The PLA2 targeted by alminoprofen is likely the secretory phospholipase A2 (sPLA2) while the COX targeted is the COX-2.

Animals↗

Lysozyme binding to endocardial endothelium mediates myocardial depression by the nitric oxide guanosine 3',5' monophosphate pathway in sepsis.

Inflammatory mediators have been implicated as a cause of reversible myocardial depression in septic shock. We previously reported that the release of lysozyme-c (Lmz-S) from leukocytes from the spleen or other organs contributes to myocardial dysfunction in Escherichia coli septic shock in dogs by binding to a cardiac membrane glycoprotein. However, the mechanism by which Lzm-S causes this depression has not been elucidated. In the present study, we tested the hypothesis that the binding of Lzm-S to a membrane glycoprotein causes myocardial depression by the formation of nitric oxide (NO). NO generation then activates soluble guanylyl cyclase and increases cyclic guanosine monophosphate (cGMP), which in turn triggers contractile impairment via activation of cGMP-dependent protein kinase (PKG). We examined these possibilities in a right ventricular trabecular preparation in which isometric contraction was used to measure cardiac contractility. We found that Lzm-S's depressant effect could be prevented by the non-specific NO synthase (NOS) inhibitor N(G)-monomethyl-l-arginine (l-NMMA). A guanylyl cyclase inhibitor (ODQ) and a PKG inhibitor (Rp-8-Br-cGMP) also attenuated Lzm-S's depressant effect as did chemical denudation of the endocardial endothelium (EE) with Triton X-100 (0.5%). In EE tissue, we further showed that Lzm-S caused NO release with use of 4,5 diaminofluorescein, a fluorescent dye that binds to NO. The present study shows that the binding of Lzm-S to EE generates NO, and that NO then activates the myocardial guanosine 3',5' monophosphate pathway leading to cardiac depression in sepsis.

Animals↗

Multiple inhibitory pathways for lipopolysaccharide- and pro-inflammatory cytokine-induced nitric oxide production in cultured astrocytes.

We previously showed that lipopolysaccharide (LPS) and pro-inflammatory cytokines utilized different mechanisms for the production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) in cultured rat astrocytes. To further characterize these regulatory pathways, we tested the effects of inhibitory factors (anti-inflammatory cytokines, cellular cAMP, and glucocorticoid) on aspects of iNOS expression (from transcription to enzyme activity) during LPS- and cytokine-induced astrocyte NO production. Anti-inflammatory cytokines (transforming growth factor-beta and interleukin-4) suppressed both LPS- and cytokine-induced NO production by reducing iNOS protein expression without affecting mRNA levels. Increased cellular cAMP levels, induced by noradrenaline or forskolin, suppressed LPS-induced, but not cytokine-induced, NO production without affecting iNOS protein expression. The glucocorticoid analog, dexamethasone, suppressed LPS-induced, but not cytokine-induced, NO production by reducing iNOS promoter activity. These different mechanisms would allow the fine control of NO concentration in the brain, as well as accounting for the multiple roles of NO in brain physiology and pathology. Moreover, these mechanisms provide useful therapeutic targets for the treatment of neurodegenerative diseases.

Animals↗

Studies of the vivo uptake of Ga-67 by an experimental abscess: concise communication.

The blocking of Ga -67 plasma protein-binding sites-by administration of scandium citrate, ferric citrate, and a colloidal hydrous ferric oxide preparation-reduced the uptake of Ga-67 in normal soft tissues and also that in the viable portion of an experimental abscess. On the other hand, enhancement of Ga-67 plasma protein binding by administration of rabbit apotransferrin increased Ga-67 uptake in both abscess and normal soft tissues. These results indicate that the pathways of Ga-67 from blood into inflammatory processes and normal soft tissues may be similar. However, when Ga-67 plasma protein binding was increased by inducing anemia, a markedly decreased Ga-67 uptake in the abscess resulted, whereas uptake in normal soft tissue was still elevated. It is possible that the discrepancy between the effects of apotransferrin and anemia on abscess-tissue uptake of Ga-67 resulted from a secondary effect produced by anemia, i.e., a decrease in the macrophage population in the abscess. Taken as a whole, the results obtained suggest that Ga-67 leaves the blood and enters inflammatory lesions by pathways that are probably quite different from those in a soft-tissue tumor, and that the routes for abscesses may be similar to those occurring in normal soft tissues.

Abscess↗

Pathways and bottlenecks in the web of inflammatory adhesion molecules and chemoattractants.

Leukocyte recruitment requires capture, rolling, activation, adhesion, and transmigration. Adhesion molecules and chemoattractants have been identified that mediate each of these steps. Their functions often overlap, but the combined absence of some molecules can lead to severe spontaneous phenotypes, as seen in CD18-/- mice, or early lethality, as in CD18-/- E-selectin-/- mice. These groups of molecules define bottlenecks that restrict the inflammatory response. Adhesion molecules and activation mechanisms can also form groups of preferential usage, or pathways. Based on these findings, a web-like model may represent the inflammatory process better than the linear cascade model. Bottlenecks and pathways depend on the degree and nature of overlapping functions, the disease process, tissue site, and the inflammatory stimulus.

Animals↗

Classification of demyelinating diseases at the interface between etiology and pathogenesis.

The classical demyelinating diseases include the 'autoimmune' inflammatory demyelinating diseases, the inflammatory demyelinating diseases of infectious aetiology, and the demyelinating or dysmyelinating diseases of genetic/hereditary background. In addition, primary demyelination is present in other conditions, such as brain ischaemia and intoxication. Irrespective of the primary aetiology, selective demyelination can be mediated through various pathogenetic pathways: the immune-mediated inflammatory pathway; the metabolic pathway; and the ischaemic/excitotoxic pathway. These pathways are only partly segregated with distinct aetiologies of demyelinating diseases, but they also reflect the way in which the patient copes with the disease-inciting event in relation to their particular genetic background. For future therapeutic strategies it will be important to interfere with the specific pathogenetic pathways of demyelination, which may be common to various demyelinating diseases, but may differ in subgroups of patients who suffer from a particular clinical demyelinating disease entity.

Animals↗

Effect of growth factors on Escherichia coli alpha-hemolysin-induced mediator release from human inflammatory cells: involvement of the signal transduction pathway.

Previously, we have shown that Escherichia coli alpha-hemolysin represents a potent stimulus for inflammatory mediator release (O2- release, beta-glucuronidase release, and leukotriene generation) from human polymorphonuclear granulocytes (PMN) as well as for histamine release from a human lymphocyte-monocyte-basophil cell suspension (LMB). In contrast, the E. coli alpha-hemolysin leads to a downregulation of cytokine release (interleukin 6 [IL-6], tumor necrosis factor alpha, and IL-1 beta) from human LMB. This study was undertaken (i) to analyze the priming efficacy of growth factors (granulocyte-macrophage colony-stimulating factor [GM-CSF] and granulocyte CSF [G-CSF]) on inflammatory mediator release from human PMN and LMB challenged with hemolysin-producing E. coli bacteria as well as with cell-free E. coli alpha-hemolysin and (ii) to identify major components involved in GM-CSF and G-CSF priming. GM-CSF pretreatment led to an increased chemiluminescence response from human PMN by up to 100%, leukotriene B4 generation was enhanced up to fivefold, and histamine release from human LMB increased from 45% +/- 15% to 75% +/- 5% (mean +/- standard distribution) of the total histamine content. G-CSF priming induced an increase in the chemiluminescence response by up to 50% +/- 5% from human PMN and an increase in histamine release from human LMB by 20% +/- 5%. The growth factors, GM-CSF and G-CSF, modulated neither beta-glucuronidase release from human PMN nor IL-8 release from human PMN and LMB challenged with the E. coli alpha-hemolysin. GM-CSF and G-CSF pretreatment increased the fluoride (NaF)-induced chemiluminescence response by up to 10-fold; the serine/threonine phosphatase inhibitor okadaic acid inhibited GM-CSF- and G-CSF-induced priming. NaF-induced histamine release was enhanced up to 60 and 30% by GM-CSF and G-CSF priming, respectively. GM-CSF and G-CSF pretreatment did not modulate phorbol 12-myristate 13-acetate-induced chemiluminescence response or histamine release. GM-CSF by itself induced an increase in 5-lipoxygenase-specific mRNA expression within 5 min. Our results indicate that (i) GM-CSF and G-CSF interact with inflammatory cells via distinct cellular signalling, (ii) the signal transduction pathway is dependent on the cellular mediator, and (iii) the use of growth factors may be a potent tool to influence the clinical outcome in infectious diseases.

Bacterial Proteins↗

Differential expression of plasma proteins and pathway enrichments in pediatric diabetic ketoacidosis.

BACKGROUND: In children with type 1 diabetes (T1D), diabetic ketoacidosis (DKA) triggers a significant inflammatory response; however, the specific effector proteins and signaling pathways involved remain largely unexplored. This pediatric case-control study utilized plasma proteomics to explore protein alterations associated with severe DKA and to identify signaling pathways that associate with clinical variables. METHODS: We conducted a proteome analysis of plasma samples from 17 matched pairs of pediatric patients with T1D; one cohort with severe DKA and another with insulin-controlled diabetes. Proximity extension assays were used to quantify 3072 plasma proteins. Data analysis was performed using multivariate statistics, machine learning, and bioinformatics. RESULTS: This study identified 214 differentially expressed proteins (162 upregulated, 52 downregulated; adj P&#x2009;<&#x2009;0.05 and a fold change&#x2009;>&#x2009;2), reflecting cellular dysfunction and metabolic stress in severe DKA. We characterized protein expression across various organ systems and cell types, with notable alterations observed in white blood cells. Elevated inflammatory pathways suggest an enhanced inflammatory response, which may contribute to the complications of severe DKA. Additionally, upregulated pathways related to hormone signaling and nitrogen metabolism were identified, consistent with increased hormone release and associated metabolic processes, such as glycogenolysis and lipolysis. Changes in lipid and fatty acid metabolism were also observed, aligning with the lipolysis and ketosis characteristic of severe DKA. Finally, several signaling pathways were associated with clinical biochemical&#xa0;variables. CONCLUSIONS: Our findings highlight differentially expressed plasma proteins and enriched signaling pathways that were associated with clinical features, offering insights into the pathophysiology of severe DKA.

Humans↗

Anti-inflammatory actions of the heme oxygenase-1 pathway.

Heme oxygenase 1 (HO-1) is induced by oxidative or nitrosative stress, cytokines and other mediators produced during inflammatory processes, likely as part of a defence system in cells exposed to stress to provide a negative feedback for cell activation and the production of mediators, which could modulate the inflammatory response. HO-1 activity results in the inhibition of oxidative damage and apoptosis, with significant reductions in inflammatory events including edema, leukocyte adhesion and migration, and production of inflammatory cytokines. HO-1 is induced by nitric oxide (NO) in different biological systems and can control the increased production of this mediator observed in many inflammatory situations. Regulatory interactions between HO-1 and cyclooxygenase (COX) pathways have also been reported. Modulation of signal transduction pathways by HO-1 or products derived from its activity, such as carbon monoxide (CO), may mediate the anti-inflammatory effects of this protein. Regulation of HO-1 activity may be a therapeutical strategy for a number of inflammatory conditions.

Animals↗

Identification of a TLR-independent pathway for Borrelia burgdorferi-induced expression of matrix metalloproteinases and inflammatory mediators through binding to integrin alpha 3 beta 1.

Borrelia burgdorferi stimulates a robust inflammatory response at sites of localization. Binding of borrelial lipoproteins to TLR-2 is one pathway important in the host response to B. burgdorferi. However, while TLR-2 is clearly important in control of infection, inflammation is actually worsened in the absence of TLR-2 or the shared TLR adapter molecule, MyD88, suggesting that there are alternative pathways regulating inflammation. Integrins are cell surface receptors that play an important role in cell to cell communications and that can activate inflammatory signaling pathways. In this study, we report for the first time that B. burgdorferi binds to integrin alpha(3)beta(1) and that binding of B. burgdorferi to this integrin results in induction of proinflammatory cytokines, chemokines, and end-effector molecules such as matrix metalloproteinases in primary human chondrocyte cells. Expression of these same molecules is not affected by the absence of MyD88 in murine articular cartilage, suggesting that the two pathways act independently in activating host inflammatory responses to B. burgdorferi. B. burgdorferi-induced alpha(3) signaling is mediated by JNK, but not p38 MAPK. In summary, we have identified a new host receptor for B. burgdorferi, integrin alpha(3)beta(1); binding of B. burgdorferi to integrin alpha(3)beta(1) results in the release of inflammatory mediators and is proposed as a TLR-independent pathway for activation of the innate immune response by the organism.

Adaptor Proteins, Signal Transducing↗

Early neoplastic progression is complement independent.

Infiltration of leukocytes into premalignant tissue is a common feature of many epithelial neoplasms and is thought to contribute to cancer development. However, the molecular and cellular regulatory mechanisms underlying activation of innate host responses to enhanced neoplastic cell proliferation are largely unknown. Considering the importance of the complement system in regulating inflammation during acute pathologic tissue remodeling, we examined the functional significance of complement component 3 (C3) as a regulator of inflammatory cell infiltration and activation during malignant progression by using a transgenic mouse model of multistage epithelial carcinogenesis, e.g., HPV16 mice. Whereas abundant deposition of C3 is a characteristic feature of premalignant hyperplasias and dysplasias coincident with leukocyte infiltration in neoplastic tissue, genetic elimination of C3 neither affects inflammatory cell recruitment toward neoplastic skin nor impacts responding pathways downstream of inflammatory cell activation, e.g., keratinocyte hyperproliferation or angiogenesis. Taken together, these data suggest that complement-independent pathways are critical for leukocyte recruitment into neoplastic tissue and leukocyte-mediated potentiation of tumorigenesis.

Animals↗

Tocilizumab: blockade of interleukin-6 signaling pathway as a therapeutic strategy for inflammatory disorders.

Interleukin (IL)-6 contributes to a myriad of physiologic and pathophysiologic processes. Among its many physiologic functions, IL-6 plays an active role in immunology, inflammatory responses, bone metabolism, arthritis and neoplasia. Overproduction of IL-6 has been implicated in the disease pathology of several inflammatory and autoimmune disorders, including rheumatoid arthritis, Castleman's disease, Crohn's disease and systemic-onset juvenile idiopathic arthritis. Interception of the IL-6 signaling pathway could thus represent a new treatment option for these diseases, given their refractory status to conventional therapy. Clinical studies with tocilizumab, a humanized monoclonal anti-IL-6 receptor antibody, have been undertaken to explore this option. Current short-term results indicate that tocilizumab dramatically improves disease activity and is well tolerated. Further long-term safety and efficacy studies are needed to confirm the therapeutic benefit of this antibody in inflammatory and autoimmune disorders.

Antibodies, Monoclonal↗