Differential regulation of IFN-gamma, IL-10 and inducible nitric oxide synthase in human T cells by cyclic AMP-dependent signal transduction pathway

Identification of bronchial epithelial genes associated with type 2 eosinophilic inflammation in asthma

BACKGROUND

Airway inflammation plays a critical role in asthma pathogenesis and pathophysiology, but the molecular pathways contributing to airway inflammation are not fully known, particularly type 2 (T2) inflammation characterized by both eosinophilia and higher fractional exhaled nitric oxide (Feno) levels.

OBJECTIVE

We sought to identify genes whose level of expression in epithelial brushing samples were associated with both bronchoalveolar lavage (BAL) eosinophilia and generation of Feno.

METHODS

We performed segmental allergen bronchoprovocation (SBP-Ag) in participants with asthma, then RNA sequencing analyses of BAL cells and brushing samples before and 48 hours after SBP-Ag to identify regulation of eosinophil recruitment and Feno changes.

RESULTS

Allergen bronchoprovocation increased Feno levels, which correlated with eosinophilia. Thirteen genes were identified in brushing samples, whose expression changed in response to SBP-Ag and correlated with both airway eosinophilia and Feno levels after SBP-Ag. Among these 13 genes, epithelial cell product CDH26/cadherin-26 contributed to the amplification of T2 inflammation, as reflected by eosinophilia and Feno, and causal mediation analyses with pro-T2 and proeosinophilic cytokine mediators in BAL fluids. Among the genes associated with reduced eosinophilia and Feno, HEY2 is known to enhance cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition, as well as to reduce apoptosis.

CONCLUSION

This unbiased RNA sequencing analysis in participants with allergic asthma revealed several epithelial cell genes, particularly CDH26, that may be critical for the development or augmentation of T2 inflammation in asthma.

Prostaglandin E2 in the Tumor Microenvironment, a Convoluted Affair Mediated by EP Receptors 2 and 4

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. SIGNIFICANCE STATEMENT: Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

Leveraging Lymphatic System Targeting in Systemic Lupus Erythematosus for Improved Clinical Outcomes

The role of advanced drug delivery strategies in drug repositioning and minimizing drug attrition rates, when applied early in drug discovery, is poised to increase the translational impact of various therapeutic strategies in disease prevention and treatment. In this context, drug delivery to the lymphatic system is gaining prominence not only to improve the systemic bioavailability of various pharmaceutical drugs but also to target certain specific diseases associated with the lymphatic system. Although the role of the lymphatic system in lupus is known, very little is done to target drugs to yield improved clinical benefits. In this review, we discuss recent advances in drug delivery strategies to treat lupus, the various routes of drug administration leading to improved lymph node bioavailability, and the available technologies applied in other areas that can be adapted to lupus treatment. Moreover, this review also presents some recent findings that demonstrate the promise of lymphatic targeting in a preclinical setting, offering renewed hope for certain pharmaceutical drugs that are limited by efficacy in their conventional dosage forms. These findings underscore the potential and feasibility of such lymphatic drug-targeting approaches to enhance therapeutic efficacy in lupus and minimize off-target effects of the pharmaceutical drugs. SIGNIFICANCE STATEMENT: The World Health Organization estimates that there are currently 5 million humans living with some form of lupus. With limited success in lupus drug discovery, turning to effective delivery strategies with existing drug molecules, as well as those in the early stage of discovery, could lead to better clinical outcomes. After all, effective delivery strategies have been proven to improve treatment outcomes.

Electrochemical evidence of nitrate release from the nitrooxy compound 4-((nitrooxy) methyl)-3-nitrobenzoic acid and its antinociceptive and anti-inflammatory activities in mice

Considering the many biological activities of nitric oxide (NO), some lines of research focused on the modulation of these activities through the provision of this mediator by designing and synthesizing compounds coupled with an NO donor group. Thus, the objectives of the present study were to carry out an electrochemical investigation of the nitrooxy compound 4-((nitrooxy) methyl)-3-nitrobenzoic acid (1) and evaluate its activities and putative mechanisms in experimental models of pain and inflammation. Voltammetric studies performed in aprotic medium (mimetic of membranes) showed important electrochemical reduction mechanisms: nitroaromatic reduction, self-protonation, and finally reductive elimination, which leads to nitrate release. Systemic administration of the nitrooxy compound (1) inhibited the nociceptive response induced by heat and the tactile hypersensitivity and paw edema induced by carrageenan in mice. The activities in the models of inflammatory pain and edema were associated with reduced neutrophil recruitment and production of inflammatory cytokines, such as interleukin (IL)-1β, IL-6, tumor necrosis factor-α and CXCL-1, and increased production of IL-10. Concluding, electrochemical analysis revealed unequivocally that electron transfer at the nitro group of the nitrooxy compound (1) results in the cleavage of the organic nitrate, potentially resulting in the generation of NO. This electrochemical mechanism may be compared to a biochemical electron-transfer mediated nitrate release that, by appropriate in vivo bioreduction (enzymatic or not) would lead to NO production. Compound (1) exhibits activities in models of inflammatory pain and edema that may be due to reduced recruitment of neutrophils and production of inflammatory cytokines and increased production of IL-10. These results reinforce the interest in the investigation of NO donor compounds as candidates for analgesic and anti-inflammatory drugs.

Diminished HIV Infection of Target CD4+ T Cells in a Toll-Like Receptor 4 Stimulated in vitro Model

Genital inflammation is associated with increased HIV acquisition risk. Induction of an inflammatory response can occur through the recognition of pathogenic or commensal microbes by Toll-like receptors (TLRs) on various immune cells. We used a in vitro peripheral blood mononuclear cell (PBMC) system to understand the contribution of TLR stimulation in inducing inflammation and the activation of target T cells, and its effect on HIV susceptibility. PBMCs were stimulated with TLR agonists LPS (TLR4), R848 (TLR7/8), and Pam3CSK4 (TLR1/2), and then infected with HIV NL4-3 AD8. Multiplexed ELISA was used to measure 28 cytokines in cell culture supernatants. Flow cytometry was used to measure the activation state (CD38 and HLA-DR), and CCR5 expression on CD4+ and CD8+ T cells. Although TLR agonists induced higher cytokine and chemokine secretion, they did not significantly activate CD4+ and CD8+ T cells and showed decreased CCR5 expression relative to the unstimulated control. Despite several classes of inflammatory cytokines and chemokines being upregulated by TLR agonists, CD4+ T cells were significantly less infectable by HIV after TLR4-stimulation than the unstimulated control. These data demonstrate that the inflammatory effects that occur in the presence TLR agonist stimulations do not necessarily translate to the activation of T cells. Most importantly, the finding that TLR4-stimulation reduces rather than increases susceptibility of CD4+ T cells to HIV infection in this in vitro system strongly suggests that the increased chemokine and possible antiviral factor expression induced by these TLR agonists play a powerful although complex role in determining HIV infection risk.

Microenvironmental signals govern the cellular identity of testicular macrophages

Testicular macrophages (TM) comprise the largest immune cell population in the mammalian testis. They are characterized by a subdued proinflammatory response upon adequate stimulation, and a polarization toward the immunoregulatory and immunotolerant M2 phenotype. This enables them to play a relevant role in supporting the archetypical functions of the testis, namely spermatogenesis and steroidogenesis. During infection, the characteristic blunted immune response of TM reflects the need for a delicate balance between a sufficiently strong reaction to counteract invading pathogens, and the prevention of excessive proinflammatory cytokine levels with the potential to disturb or destroy spermatogenesis. Local microenvironmental factors that determine the special phenotype of TM have just begun to be unraveled, and are discussed in this review.

Pentoxifylline inhibits TLR- and inflammasome-mediated in vitro inflammatory cytokine production in human blood with greater efficacy and potency in newborns

BACKGROUND

Toll-like receptor (TLR)-mediated inflammation may contribute to neonatal sepsis, for which pentoxifylline (PTX), a phosphodiesterase inhibitor that raises intracellular cAMP, is a candidate adjunctive therapy. We characterized the anti-inflammatory effects of PTX toward TLR-mediated production of inflammatory (tumor necrosis factor (TNF) and interleukin (IL)-1β) and proresolution (IL-6 and IL-10) cytokines in human newborn and adult blood.

METHODS

Newborn cord and adult blood were treated with PTX (50-400 µmol/l) before, during or after stimulation with LPS (TLR4 agonist), R848 (TLR7/8 agonist) or LPS/ATP (inflammasome activation). Cytokines were measured by multiplex assay (supernatants), intracellular cytokines and signaling molecules by flow cytometry, and mRNA by quantitative real-time PCR.

RESULTS

Whether added 2 h pre-, simultaneously to, or 2 h post-TLR stimulation, PTX inhibited TLR-mediated cytokine production in a concentration-dependent manner, with greater efficacy and potency in newborn blood, decreasing intracellular TNF and IL-1β with relative preservation of IL-10 and IL-6. PTX decreased TLR-mediated TNF mRNA while increasing IL-10 mRNA. Neonatal plasma factors contributed to the anti-inflammatory effects of PTX in newborn blood that were independent of soluble TNF receptor concentrations, p38 MAPK phosphorylation and IĸB degradation.

CONCLUSION

PTX is a potent and efficacious inhibitor of TLR-mediated inflammatory cytokines in newborn cord blood and a promising neonatal anti-inflammatory agent.

Identification and functional characterization of the house finch interleukin-1β

Interleukin-1β (IL-1β), an inflammatory cytokine of the IL-1 family, is primarily produced as a precursor protein by monocytes and macrophages, then matures and becomes activated through proteolytic catalysis. Although the biological characteristics of avian IL-1β are well known, little information is available about its biological role in songbird species such as house finches that are vulnerable to naturally-occurring inflammatory diseases. In this study, house finch IL-1β (HfIL-1β) was cloned, expressed, and its biological function examined. Both precursor and mature forms of HfIL-1β consisting of 269 and 162 amino acids, respectively, were amplified from total RNA of spleen and cloned into expression vectors. HfIL-1β showed high sequential and tertiary structural similarity to chicken homologue that allowed detection of the expressed mature recombinant HfIL-1β (rHfIL-1β) with anti-ChIL-1β antibody by immunoblot analysis. For further characterization, we used primary splenocytes and hepatocytes that are predominant sources of IL-1β upon stimulation, as well as suitable targets to stimulation by IL-1β. Isolated house finch splenocytes were stimulated with rHfIL-1β in the presence and absence of concanavalin A (Con A), RNA was extracted and transcript levels of Th1/Th2 cytokines and a chemokine were measured by qRT-PCR. The addition of rHfIL-1β induced significant enhancement of IL-2 transcript, a Th1 cytokine, while transcription of IL-1β and the Th2 cytokine IL-10 was slightly enhanced by rHfIL-1β treatment. rHfIL-1β also led to elevated levels of the chemokine CXCL1 and nitric oxide production regardless of co-stimulation with Con A. In addition, the production of the acute phase protein serum amyloid A and the antimicrobial peptide LEAP2 was observed in HfIL-1β-stimulated hepatocytes. Taken together, these observations revealed the basic functions of HfIL-1β including the stimulatory effect on cell proliferation, production of Th1/Th2 cytokines and acute phase proteins by immune cells, thus providing valuable insight into how HfIL-1β is involved in regulating inflammatory response.

IFNγ-Dependent Interactions between ICAM-1 and LFA-1 Counteract Prostaglandin E2-Mediated Inhibition of Antitumor CTL Responses

Tumor-expressed ICAM-1 interaction with LFA-1 on naïve tumor-specific CD8(+) T cells not only stabilizes adhesion, but, in the absence of classical B7-mediated costimulation, is also able to provide potent alternative costimulatory signaling resulting in the production of antitumor cytotoxic T lymphocyte (CTL) responses. This study shows that overproduction of prostaglandin (PG) E2 by metastatic murine renal carcinoma (Renca) cells inhibited direct priming of tumor-specific CTL responses in vivo by preventing the IFNγ-dependent upregulation of ICAM-1 that is vital during the initial priming of naïve CD8(+) T cells. The addition of exogenous IFNγ during naïve CD8(+) T-cell priming abrogated PGE2-mediated suppression, and overexpression of ICAM-1 by tumor cells restored IFNγ production and proliferation among PGE2-treated tumor-specific CD8(+) T cells; preventing tumor growth in vivo These findings suggest that novel anticancer immunotherapies, which increase expression of ICAM-1 on tumor cells, could help alleviate PGE2-mediated immunosuppression of antitumor CTL responses. Cancer Immunol Res; 4(5); 400-11. ©2016 AACR.

The Immunomodulatory Effects of Mesenchymal Stem Cells in Prevention or Treatment of Excessive Scars

Excessive scars, including keloids and hypertrophic scars, result from aberrations in the process of physiologic wound healing. An exaggerated inflammatory process is one of the main pathophysiological contributors. Scars may cause pain, and pruritis, limit joint mobility, and cause a range of cosmetic deformities that affect the patient's quality of life. Extensive research has been done on hypertrophic scar and keloid formation that has resulted in the plethora of treatment and prevention methods practiced today. Mesenchymal stem cells, among their multifunctional roles, are known regulators of inflammation and have been receiving attention as a major candidate for cell therapy to treat or prevent excessive scars. This paper extensively reviews the body of research examining the mechanism and potential of stem cell therapy in the treatment of excessive scars.

R, Sheridan JF. Imipramine attenuates neuroinflammatory signaling and reverses stress-induced social avoidance

Psychosocial stress is associated with altered immunity, anxiety and depression. Previously we showed that repeated social defeat (RSD) promoted microglia activation and social avoidance behavior that persisted for 24days after cessation of RSD. The aim of the present study was to determine if imipramine (a tricyclic antidepressant) would reverse RSD-inducedsocial avoidance and ameliorate neuroinflammatory responses. To test this, C57BL/6 mice were divided into treatment groups. One group from RSD and controls received daily injections of imipramine for 24days, following 6 cycles of RSD. Two other groups were treated with saline. RSD mice spent significantly less time in the interaction zone when an aggressor was present in the cage. Administration of imipramine reversed social avoidance behavior, significantly increasing the interaction time, so that it was similar to that of control mice. Moreover, 24days of imipramine treatment in RSD mice significantly decreased stress-induced mRNA levels for IL-6 in brain microglia. Following ex vivo LPS stimulation, microglia from mice exposed to RSD, had higher mRNA expression of IL-6, TNF-α, and IL-1β, and this was reversed by imipramine treatment. In a second experiment, imipramine was added to drinking water confirming the reversal of social avoidant behavior and decrease in mRNA expression of IL-6 in microglia. These data suggest that the antidepressant imipramine may exert its effect, in part, by down-regulating microglial activation.

The influence of arsenic trioxide on the cell cycle, apoptosis and expression of cyclin D1 in the Jurkat cell line

Cyclin D1 drives cell cycle progression at the G1/S transition and is believed to play a significant role in tumorigenesis, contributing to efficient proliferation of many cancer cells. Consequently, it is also recognized as an end-point biomarker of therapeutic outcome for different treatment modalities in cancer. In this study we aimed to evaluate the expression and localization of cyclin D1 in arsenic trioxide (ATO) treated Jurkat cells (lymphoblastic leukemia cell line) and to correlate these results with the extent of cell death and/or cell cycle alterations. Jurkat cells were incubated with increasing concentrations of ATO (0.2, 0.6 and 1.0μM) for 24h in standard cell culture conditions. To reach our goal we performed annexin V/PI labeling for detection of cell death and RNase/PI labeling for evaluation of cell cycle distribution, which were followed by the respective flow cytometric analyses of ATO-treated Jurkat cells. Transmission electron microscopy was applied for visualization of the cell ultrastructure. For cyclin D1 estimation a biparametric cyclinD1/cell cycle assay was done and localization of the protein was shown after immuno-labeling using light microscopy (ABC procedure) and confocal fluorescence microscopy. We found that there were no significant changes in the percentages of cyclin D1-positive cells after the treatment with ATO, but at the same time mean fluorescence intensity reflecting cyclin D1 content was gradually increasing along with the cell cycle progression, irrespective of the applied dose of the drug. On the other hand, we found a nuclear-cytoplasmic shift of this protein as a major treatment-related response, which was in good accord with an increased rate of cell death and suggested that cyclin D1 cytoplasmic degradation is an important determinant of the therapeutic efficiency of ATO in the Jurkat cell line.

Mesenchymal stem cell therapy for attenuation of scar formation during wound healing

Scars are a consequence of cutaneous wound healing that can be both unsightly and detrimental to the function of the tissue. Scar tissue is generated by excessive deposition of extracellular matrix tissue by wound healing fibroblasts and myofibroblasts, and although it is inferior to the uninjured skin, it is able to restore integrity to the boundary between the body and its environment. Scarring is not a necessary process to repair the dermal tissues. Rather, scar tissue forms due to specific mechanisms that occur during the adult wound healing process and are modulated primarily by the inflammatory response at the site of injury. Adult tissue-derived mesenchymal stem cells, which participate in normal wound healing, are trophic mediators of tissue repair. These cells participate in attenuating inflammation in the wound and reprogramming the resident immune and wound healing cells to favor tissue regeneration and inhibit fibrotic tissue formation. As a result, these cells have been considered and tested as a likely candidate for a cellular therapy to promote scar-less wound healing. This review identifies specific mechanisms by which mesenchymal stem cells can limit tissue fibrosis and summarizes recent in vivo studies where these cells have been used successfully to limit scar formation.

Prostaglandin E2 affects T cell responses through modulation of CD46 expression

The ubiquitous protein CD46, a regulator of complement activity, promotes T cell activation and differentiation toward a regulatory Tr1-like phenotype. The CD46-mediated differentiation pathway is defective in several chronic inflammatory diseases, underlying the importance of CD46 in controlling T cell function and the need to understand its regulatory mechanisms. Using an RNA interference-based screening approach in primary T cells, we have identified that two members of the G protein-coupled receptor kinases were involved in regulating CD46 expression at the surface of activated cells. We have investigated the role of PGE(2), which binds to the E-prostanoid family of G protein-coupled receptors through four subtypes of receptors called EP 1-4, in the regulation of CD46 expression and function. Conflicting roles of PGE(2) in T cell functions have been reported, and the reasons for these apparent discrepancies are not well understood. We show that addition of PGE(2) strongly downregulates CD46 expression in activated T cells. Moreover, PGE(2) differentially affects T cell activation, cytokine production, and phenotype depending on the activation signals received by the T cells. This was correlated with a distinct pattern of the PGE(2) receptors expressed, with EP4 being preferentially induced by CD46 activation. Indeed, addition of an EP4 antagonist could reverse the effects observed on cytokine production after CD46 costimulation. These data demonstrate a novel role of the PGE(2)-EP4 axis in CD46 functions, which might at least partly explain the diverse roles of PGE(2) in T cell functions.

Lack of nitric oxide synthases increases lipoprotein immune complex deposition in the aorta and elevates plasma sphingolipid levels in lupus

Systemic lupus erythematosus (SLE) patients display impaired endothelial nitric oxide synthase (eNOS) function required for normal vasodilatation. SLE patients express increased compensatory activity of inducible nitric oxide synthase (iNOS) generating excess nitric oxide that may result in inflammation. We examined the effects of genetic deletion of NOS2 and NOS3, encoding iNOS and eNOS respectively, on accelerated vascular disease in MRL/lpr lupus mouse model. NOS2 and NOS3 knockout (KO) MRL/lpr mice had higher plasma levels of triglycerides (23% and 35%, respectively), ceramide (45% and 21%, respectively), and sphingosine 1-phosphate (S1P) (21%) compared to counterpart MRL/lpr controls. Plasma levels of the anti-inflammatory cytokine interleukin 10 (IL-10) in NOS2 and NOS3 KO MRL/lpr mice were lower (53% and 80%, respectively) than counterpart controls. Nodule-like lesions in the adventitia were detected in aortas from both NOS2 and NOS3 KO MRL/lpr mice. Immunohistochemical evaluation of the lesions revealed activated endothelial cells and lipid-laden macrophages (foam cells), elevated sphingosine kinase 1 expression, and oxidized low-density lipoprotein immune complexes (oxLDL-IC). The findings suggest that advanced vascular disease in NOS2 and NOS3 KO MRL/lpr mice maybe mediated by increased plasma triglycerides, ceramide and S1P; decreased plasma IL-10; and accumulation of oxLDL-IC in the vessel wall. The results expose possible new targets to mitigate lupus-associated complications.

Role of PGE2 in asthma and nonasthmatic eosinophilic bronchitis

Eosinophilic bronchitis is a common cause of chronic cough, which like asthma is characterized by sputum eosinophilia, but unlike asthma there is no variable airflow obstruction or airway hyperresponsiveness. Several studies suggest that prostaglandins may play an important role in orchestrating interactions between different cells in several inflammatory diseases such as asthma. PGE₂ is important because of the multiplicity of its effects on immune response in respiratory diseases; however, respiratory system appears to be unique in that PGE₂ has beneficial effects. We described that the difference in airway function observed in patients with eosinophilic bronchitis and asthma could be due to differences in PGE₂ production. PGE₂ present in induced sputum supernatant from NAEB patients decreases BSMC proliferation, probably due to simultaneous stimulation of EP2 and EP4 receptors with inhibitory activity. This protective effect of PGE₂ may not only be the result of a direct action exerted on airway smooth-muscle proliferation but may also be attributable to the other anti-inflammatory actions.

Concise review: clinical translation of wound healing therapies based on mesenchymal stem cells

There is enormous worldwide demand for therapies to promote the efficient resolution of hard-to-heal wounds with minimal appearance of scarring. Recent in vitro studies with mesenchymal stem cells (MSCs) have identified numerous mechanisms by which these cells can promote the process of wound healing, and there is significant interest in the clinical translation of an MSC-based therapy to promote dermal regeneration. This review provides a systematic analysis of recent preclinical and clinical research to evaluate the use of MSCs in wound healing applications. These in vivo studies provide overwhelming evidence that MSCs can accelerate wound closure by modulating the inflammatory environment, promoting the formation of a well-vascularized granulation matrix, encouraging the migration of keratinocytes, and inhibiting apoptosis of wound healing cells. The trophic effects of MSC therapy also appear to augment wound healing in diabetic tissues, thereby preventing the formation of nonhealing ulcers. Finally, a number of delivery systems have been evaluated and indicate that MSCs could be the basis of a versatile therapy to fulfill the clinical needs for dermal regeneration. However, despite the apparent advantages of MSC-based therapies, there have been only limited clinical investigations of this type of therapy in humans. Thus, our review concludes with a discussion of the translational barriers that are limiting the widespread clinical use of MSCs to enhance wound healing.

Mechanism of Liver Injury during Obstructive Jaundice: Role of Nitric Oxide, Splenic Cytokines, and Intestinal Flora

To elucidate the roles of enteric bacteria and immunological interactions among liver, spleen and intestine in the pathogenesis of liver injury during obstructive jaundice, we studied the effects of antibiotics and splenectomy on bile-duct-ligated C57BL mice. When animals were subjected to bile-duct-ligation (BDL), plasma levels of bilirubin, alanine aminotransferase and aspartate aminotransferase increased markedly. However, the increases in plasma transaminases were significantly lower in splenectomized or antibiotics-treated groups than in the control BDL group. Histological examination revealed that liver injury was also low in the two groups. BDL markedly increased plasma level of interferon-γ (IFN-γ) and the expression of inducible nitric oxide synthase (iNOS) in liver and spleen. These changes were suppressed either by splenectomy or administration of antibiotics. Kinetic analysis revealed that BDL-induced liver injury and the increase of interleukin-10 (IL-10) and INF-γ were lower in iNOS^−/− than in wild type animals. BDL markedly increased the expression of IgA in colonic mucosa. These observations suggest that enteric bacteria, nitric oxide and cytokines including IFN-γ and IL-10 derived from spleen and intestines form a critical network that determines the extent of liver injury during obstructive jaundice.

Role of increased guanosine triphosphate cyclohydrolase-1 expression and tetrahydrobiopterin levels upon T cell activation

Tetrahydrobiopterin (BH(4)) is an essential co-factor for the nitric-oxide (NO) synthases, and in its absence these enzymes produce superoxide (O(2)(·-)) rather than NO. The rate-limiting enzyme for BH(4) production is guanosine triphosphate cyclohydrolase-1 (GTPCH-1). Because endogenously produced NO affects T cell function, we sought to determine whether antigen stimulation affected T cell GTPCH-1 expression and ultimately BH(4) levels. Resting T cells had minimal expression of inducible NOS (NOS2), endothelial NOS (NOS3), and GTPCH-1 protein and nearly undetectable levels of BH(4). Anti-CD3 stimulation of T cells robustly stimulated the coordinated expression of NOS2, NOS3, and GTPCH-1 and markedly increased both GTPCH-1 activity and T cell BH(4) levels. The newly expressed GTPCH-1 was phosphorylated on serine 72 and pharmacological inhibition of casein kinase II reduced GTPCH-1 phosphorylation and blunted the increase in T cell BH(4). Inhibition of GTPCH-1 with diaminohydroxypyrimidine (1 mmol/liter) prevented T cell BH(4) accumulation, reduced NO production, and increased T cell O(2)(·-) production, due to both NOS2 and NOS3 uncoupling. GTPCH-1 inhibition also promoted TH(2) polarization in memory CD4 cells. Ovalbumin immunization of mice transgenic for an ovalbumin receptor (OT-II mice) confirmed a marked increase in T cell BH(4) in vivo. These studies identify a previously unidentified consequence of T cell activation, promoting BH(4) levels, NO production, and modulating T cell cytokine production.

Adjuvant effect of liposome in chicken result from induction of nitric oxide

Intranasal delivery of liposome-encapsulated inactivated Newcastle Disease virus (NDV) is known to be an effective vaccine for inducing immunity in the respiratory tract from our previous reports. Four-week-old specific pathogen-free chickens were intranasally immunized with NDV entrapped in phosphatidylcholine-liposomes (PC-Lip). The mucosal levels of anti-NDV s-immunoglobulin A (IgA), serum IgG, a high hemagglutination inhibition titer (1:640), and the high survival rate with the PC-Lip vaccine were comparable to those of our previous report. The immune mechanisms of the PC-Lip adjuvant were determined by in vitro cellular experiments using the NO production of chicken spleen macrophages. The most important finding of this study was proving that macrophages were stimulated by PC-Lip via the extracellular regulated kinase (ERK) 1/2 and nuclear factor (NF)-κB activation pathways. This finding may be useful for developing potent mucosal vaccine delivery systems in the future.

Regulation of lymphocytes by nitric oxide

Shortly after the identification of nitric oxide (NO) as a product of macrophages, it was discovered that NO generated by inducible NO synthase (iNOS) inhibits the proliferation of T lymphocytes. Since then, it has become clear that iNOS activity also regulates the development, differentiation, and/or function of various types of T cells and B cells and also affects NK cells. The three key mechanisms underlying the iNOS-dependent immunoregulation are (a) the modulation of signaling processes by NO, (b) the depletion of arginine, and (c) the alteration of accessory cell functions. This chapter highlights important principles of iNOS-dependent immunoregulation of lymphocytes and also reviews more recent evidence for an effect of endothelial or neuronal NO synthase in lymphocytes.

Comparative study on modeccin- and phytohemagglutinin (PHA)-induced secretion of cytokines and nitric oxide (NO) in RAW264.7 cells

The effects of cytotoxic lectins, modeccin and phytohemagglutinin (PHA) on mouse macrophage cell line RAW264.7 was studied by detecting the induction of inflammatory mediators. Results showed that modeccin induced the release of tumor necrosis factor-α (TNF-α) from RAW264.7 cells with a bell-shape concentration-dependent profile. PHA that showed no significant cytotoxicity on RAW264.7 cells up to 100,000 ng/ml induced much higher level of TNF-α than modeccin. PHA simultaneously induced the secretion of granulocyte colony stimulation factor (G-CSF) from RAW264.7 cells with even much higher level than that of TNF-α, whereas modeccin did not. Furthermore, PHA induced the secretion of nitric oxide (NO) in RAW264.7 cells, while no significant level of NO was detected in the modeccin-treated cells. NH₄Cl (a lysomotoropic agent) and cycloheximide (a ribosome inhibitor) strongly inhibited modeccin-induced TNF-α secretion, but no significant inhibitory effects of these reagents on the PHA-induced TNF-α secretion were observed. Contrary to modeccin-induced TNF-α secretion, even slightly increased TNF-α secretion was observed in PHA-treated cells in the presence of 10 mM NH₄Cl. In addition, the inhibition profiles of modeccin-induced TNF-α secretion by various kinase inhibitors were different from those of PHA. These results suggested that the action mode of modeccin to stimulate RAW264.7 cells leading to the secretion of inflammatory molecules, including TNF-α, is distinct from that of PHA. On the other hand, significantly increased translocation of activator protein-1 (AP-1), a crucial transcription factor involved in expression of inflammatory molecules, into nucleus was observed in RAW264.7 cells treated with PHA and modeccin.

Neuroimmune pharmacology of neurodegenerative and mental diseases

Neuroimmune pharmacology is a newly emerging field that intersects with neuroscience, immunology, and pharmacology and that is seeking avenues for translational research and better understanding of disease mechanisms. It focuses on the immunity of the central nervous system (CNS) which is greatly influenced by endogenous effectors, such as cytokines and neurotransmitters, and by exogenous substances, including therapeutic compounds, infectious pathogens, and drugs of abuse. In this article, we attempt to raise awareness of the pivotal discovery of how those mediators affect the immunity of the CNS in both physiological conditions and processes of certain mental illnesses, including psychiatric disorders, neurodegenerative diseases, and cerebral dysfunctions due to drugs of abuse. The abnormality in cytokine networks, neurotransmitter homeostasis, and other immune responses may be involved in the neuropathology associated with those mental illnesses, and the therapeutic effects of the potential treatments can be attributed, at least partially, to their immunomodulatory activities. However, the resulting inflammatory cytokines from certain treatments frequently cause psychiatric complications. In addition, the poor neuropathological outcomes frequently found among drug abusers with HIV-1 infection appear to be related to the neurotoxic and immunomodulatory effects of the drugs used. Importantly, glial cells, especially microglia and astrocytes, are key players in the immunomodulatory activities in the CNS, and the functioning CNS is largely dependent upon the reciprocal interactions between neurons and glial cells. Therefore, glia-neuron interactions have become a critical issue for further understanding the disease mechanism. From this review, readers will gain insights into the new field of neuroimmune pharmacology, with a focus on the impacts of CNS immunity on the mental illnesses.

Modulation of cytokine production by cyclic adenosine monophosphate analogs in human leukocytes

Cyclic adenosine monophosphate (cAMP) is a well-known second messenger that operates through different signaling molecules, including protein kinase A (PKA) and guanine exchange proteins directly activated by cAMP (EPAC). Cell-permeable cAMP analogs such as 8-(4-chloro-phenyl-thio)-cAMP (8-pCPT-cAMP) modulate cytokine secretion by different leukocyte subsets, including T cells and monocytes. Since cAMP-modulating drugs such as phosphodiesterase inhibitors are being tested in inflammatory disorders such as asthma and chronic obstructive lung disease, it is important to obtain more insight into the regulation of cytokine production by cAMP. To address the signaling molecules involved in cAMP-mediated modulation of cytokine production, we used cAMP derivatives such as N(6)-benzoyladenosine-cAMP (6-Bnz-cAMP) and 8-pCPT-2-O-methyl cAMP (8-pCPT-2'-O-Me-cAMP), which selectively activate either PKA or EPAC, respectively. We show that in T cells, 6-Bnz-cAMP exerts similar globally inhibiting effects on cytokine secretion as 8-pCPT-cAMP, indicating that these effects are mediated by PKA. On the contrary, 8-pCPT-2'-O-Me-cAMP specifically inhibits the production of interleukin-10 (IL-10) in lipopolysaccharide-activated T-cell-depleted peripheral blood mononuclear cells, whereas the production of IL-1β, tumor necrosis factor α, and IL-12 is not or hardly affected. Inhibition by 8-pCPT-2'-O-Me-cAMP of IL-10 production was confirmed using purified monocytes. Further, in B cells 6-Bnz-cAMP, but not 8-pCPT-2'-O-Me-cAMP, stimulated IL-10 production. In conclusion, cAMP stimulates IL-10 production via PKA in activated B cells, but inhibits IL-10 production in activated monocytes through EPAC. We speculate that selective effects of PKA and EPAC on cytokine production in leukocyte subsets open up therapeutic possibilities using selective activators or inhibitors of EPAC or PKA.

Regulation of T cells in airway disease by beta-agonist

It is widely recognized that Th2 cytokines derived from T cells play a major role in the development of allergic lung inflammation that causes most asthma. Beta-agonists are important rescue and maintenance therapies for asthma, yet our understanding of beta-agonist effects on T cell biology is surprisingly poor. Recent studies using both cell culture and more integrative models are beginning to reveal beta-agonist regulation of T cell signaling and function that may be important in the pathogenesis and treatment of asthma and possibly other inflammatory diseases. Here we provide a comprehensive review of the literature concerning beta-agonist effects on T cells, and discuss the relevance of emerging paradigms of beta-adrenergic receptor signaling to T cell function.

cAMP activates the generation of reactive oxygen species and inhibits the secretion of IL-6 in peripheral blood mononuclear cells from type 2 diabetic patients

Peripheral blood mononuclear cells (PBMNC) from patients with type 2 diabetes (DM2) have generated higher levels of reactive oxygen species (ROS) that were higher than those in cells from healthy individuals. In the presence of a cAMP-elevating agent, ROS production was significantly activated in PBMNC from DM2 patients but it was inhibited in cells from healthy subjects. Higher levels of IL-6 has been detected in the supernatant of PBMNC cultures from DM2 patients in comparison with healthy controls. When cells were cultured in the presence of a cAMP-elevating agent, the level of IL-6 decreased has by 46% in the supernatant of PBMNC from DM2 patients but it remained unaltered in controls. No correlations between ROS and IL-6 levels in PBMNC from DM2 patients or controls have been observed. Secretions of IL-4 or IFNgamma by PBMNC from patients or controls have not been affected by the elevation of cAMP. cAMP elevating agents have activated the production of harmful reactive oxidant down modulated IL-6 secretion by these cells from DM2 patients, suggesting an alteration in the metabolic response possibly due to hyperglicemia. The results suggest that cAMP may play an important role in the pathogenesis of diabetes.

Histamine plays an essential regulatory role in lung inflammation and protective immunity in the acute phase of Mycobacterium tuberculosis infection

The course and outcome of infection with mycobacteria are determined by a complex interplay between the immune system of the host and the survival mechanisms developed by the bacilli. Recent data suggest a regulatory role of histamine not only in the innate but also in the adaptive immune response. We used a model of pulmonary Mycobacterium tuberculosis infection in histamine-deficient mice lacking histidine decarboxylase (HDC(-/-)), the histamine-synthesizing enzyme. To confirm that mycobacterial infection induced histamine production, we exposed mice to M. tuberculosis and compared responses in C57BL/6 (wild-type) and HDC(-/-) mice. Histamine levels increased around fivefold above baseline in infected C57BL/6 mice at day 28 of infection, whereas only small amounts were detected in the lungs of infected HDC(-/-) mice. Blocking histamine production decreased both neutrophil influx into lung tissue and the release of proinflammatory mediators, such as interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), in the acute phase of infection. However, the accumulation and activation of CD4(+) T cells were augmented in the lungs of infected HDC(-/-) mice and correlated with a distinct granuloma formation that contained abundant lymphocytic infiltration and reduced numbers of mycobacteria 28 days after infection. Furthermore, the production of IL-12, gamma interferon, and nitric oxide, as well as CD11c(+) cell influx into the lungs of infected HDC(-/-) mice, was increased. These findings indicate that histamine produced after M. tuberculosis infection may play a regulatory role not only by enhancing the pulmonary neutrophilia and production of IL-6 and TNF-alpha but also by impairing the protective Th1 response, which ultimately restricts mycobacterial growth.

Protease-activated receptors and prostaglandins in inflammatory lung disease

Protease-activated receptors (PARs) are a novel family of G protein-coupled receptors. Signalling through PARs typically involves the cleavage of an extracellular region of the receptor by endogenous or exogenous proteases, which reveals a tethered ligand sequence capable of auto-activating the receptor. A considerable body of evidence has emerged over the past 20 years supporting a prominent role for PARs in a variety of human physiological and pathophysiological processes, and thus substantial attention has been directed towards developing drug-like molecules that activate or block PARs via non-proteolytic pathways. PARs are widely expressed within the respiratory tract, and their activation appears to exert significant modulatory influences on the level of bronchomotor tone, as well as on the inflammatory processes associated with a range of respiratory tract disorders. Nevertheless, there is debate as to whether the principal response to PAR activation is an augmentation or attenuation of airways inflammation. In this context, an important action of PAR activators may be to promote the generation and release of prostanoids, such as prostglandin E(2), which have well-established anti-inflammatory effects in the lung. In this review, we primarily focus on the relationship between PARs, prostaglandins and inflammatory processes in the lung, and highlight their potential role in selected respiratory tract disorders, including pulmonary fibrosis, asthma and chronic obstructive pulmonary disease.

Effects of early enteral nutrition supplemented with arginine on intestinal mucosal immunity in severely burned mice

BACKGROUND

To investigate the effects of early enteral nutrition (EN) supplemented with Arginine (Arg) on intestinal mucosal immunity in severely burned mice.

METHODS

Forty-four mice were randomly assigned into four groups: a sham injury+EN group (n=10), a sham injury+EN+Arg group (n=10), a burn+EN group (n=12), and a burn+EN+Arg group (n=12) and the mice in two experimental groups received a 20% total body surface area (TBSA), full-thickness scald burn on the back. Then, the burned mice were given a 175 kcal/kg body wt/day of conventional enteral nutrition or an isonitrogenous and isocaloric enteral nutrition supplemented with Arg by gastric gavage for 7 days. There was isonitrogenous and isocaloric intake in two experimental groups. The mice in two control groups received the same procedures as above, except for burn injury. On day 7 after injury, all mice among four groups were euthanized and the entire intestine was harvested. Intestinal immunoglobulin A (IgA) levels, total lymphocyte yield, and lymphocyte subpopulations in Peyer's patches were analyzed. Levels of IFN-gamma, IL-2, IL-4 and IL-10 in gut homogenates were also measured by ELISA.

RESULTS

Total lymphocyte yield, numbers of lymphocyte subpopulations, and intestinal IgA levels in the EN+ARG group were higher than those in the EN group (p<0.05). Levels of gut tissue cytokines were significantly altered with enteral Arg supplementation: levels of IL-4 and IL-10 were increased, and levels of IFN-gamma and IL-2 declined, when compared with the EN-fed mice (p<0.05).

CONCLUSIONS

The results of this study suggested that enteral nutrition supplemented with Arg has changed the cytokine concentrations in intestinal homogenates from a pro- to an anti-inflammatory profile, increased sIgA levels and changed lymphocytes in severely burned mice.

cAMP regulates IL-10 production by normal human T lymphocytes at multiple levels: a potential role for MEF2

Signal transduction by the cAMP/cAMP-dependent protein kinase A (PKA) pathway is triggered through multiple receptors and is important for many processes in a variety of cells. In T cells, the engagement of the TCR-CD3 complex induces cAMP, a second messenger that controls immune response. IL-10, produced by a variety of lymphocyte subpopulations, is an important regulator of this response exerting a wide range of immunomodulatory actions. Elevation of cAMP has been shown to increase IL-10 production by monocytes. However, the mechanism of cAMP mediated regulation of IL-10 production by T lymphocytes remains unclear. In this study using normal peripheral T lymphocytes stimulated either through the TCR-CD3 complex or the TCR-CD3 and the CD28 molecule, we show that IL-10 is produced mainly by memory T lymphocytes after either way of stimulation and is drastically inhibited (70-90%) by cAMP elevating agents. cAMP mediated inhibition was reversed by the use of the specific PKA inhibitor Rp-8-Br-cAMP but not by the addition of exogenous rhIL-2, indicating that the inhibitory effect depends on PKA activation and is not secondary to IL-2 inhibition. Inhibition is taking place at both transcriptional and posttranscriptional level. Transfection of a luciferase reporter plasmid carrying the IL-10 promoter in T cells, revealed that TCR/CD28-induced activation was inhibited by 60% by cAMP elevation. The most sensitive part to cAMP mediated inhibition was a fragment of 135 bp upstream of TATA box, which contains multiple binding sites for MEF-2. Overexpression of MEF-2 in the same cells increased IL-10 promoter activity by 2.5-fold. Stimulation through TCR/CD28 increased MEF-2 binding in its corresponding binding sites which was inhibited by 80% in the presence of cAMP elevating agents. These results suggest that the inhibitory effect of cAMP on IL-10 production by normal peripheral T lymphocytes is cell type and stimulus specific, exerted on multiple levels and involves MEF2 transcription factor.

Lung resident mesenchymal stem cells isolated from human lung allografts inhibit T cell proliferation via a soluble mediator

Development of allograft rejection continues to be the major determinant of morbidity and mortality postlung transplantation. We have recently demonstrated that a population of donor-derived mesenchymal stem cells is present in human lung allografts and can be isolated and expanded ex vivo. In this study, we investigated the impact of lung resident mesenchymal stem cells (LR-MSCs), derived from allografts of human lung transplant recipients, on T cell activation in vitro. Similar to bone marrow-derived MSCs, LR-MSCs did not express MHC II or the costimulatory molecules CD80 or CD86. In vitro, LR-MSCs profoundly suppressed the proliferative capacity of T cells in response to a mitogenic or an allogeneic stimulus. The immunosuppressive function of LR-MSCs was also noted in the absence of direct cell contact, indicating that LR-MSCs mediated their effect predominantly via a soluble mediator. LR-MSCs isolated from lung transplant recipients demonstrated PGE(2) secretion at baseline (385 +/- 375 pg/ml), which increased in response to IL-1beta (1149 +/- 1081 pg/ml). The addition of PG synthesis inhibitors (indomethacin and NS-398) substantially abrogated LR-MSC-mediated immunosuppression, indicating that PGE(2) may be one of the major soluble mediators impacting T cell activity. This is the first report to demonstrate that human tissue-derived MSCs isolated from an allogeneic environment have the potential to mediate immunological responses in vitro.

Production of nitric oxide by carp (Cyprinus carpio L.) kidney leukocytes is regulated by cyclic 3',5'-adenosine monophosphate

The inducible nitric oxide synthase (iNOS) plays a central role in the inflammatory reactions that follow infection or tissue damage. Induction of nitric oxide (NO) synthesis by bacterial lipopolysaccharide (LPS) depends on activation of G protein-coupled receptors in mammals. Thus, it was our intention to evaluate whether similar mechanisms are involved in iNOS activation in fish leukocytes. Therefore, the participation of membrane-bound receptors which activate effectors via G proteins has been confirmed using the G protein inhibitor suramin. Furthermore, the NO produced by iNOS performs both beneficial and detrimental actions. It is thus conceivable that regulatory mechanisms exist which control the timing and intensity of NO production by iNOS in order to outweigh protective effects against detrimental ones. The second messenger cAMP produced by adenylyl cyclases (ACs) plays a key role in the regulation of many cellular functions. Since cAMP signaling inhibits numerous immunological reactions, studies have been carried out to determine whether cAMP-dependent pathways could inhibit NO production by carp leukocytes as well. To measure cellular responses such as NO production by carp leukocytes derived from head and trunk kidneys treatments were performed with the cAMP elevating agents forskolin and dibutyryl-cAMP (db-cAMP) prior to stimulation with Aeromonas hydrophila. Pharmacological studies in stimulated kidney leukocytes showed that increased intracellular cAMP levels lead to reduced NO formation. This reduction of NO production was not due to decreased cell numbers, since a tetrazolium dye-based assay revealed no reduction of cell viability by cyclic nucleotide elevating agents. Thus, our data provide evidence that the AC/cAMP signaling pathway is well established in carp leukocytes. Cyclic AMP leads to type II immune response. We provide evidence that the predominant AC in fish leukocytes is a particulate enzyme due to its sensitivity to forskolin. Treatment of leukocytes with agents increasing intracellular cAMP gave clear evidence for participation of this cyclic nucleotide in immune signaling.

Thymic stromal lymphopoietin (TSLP) as a bridge between infection and atopy

The rising worldwide prevalence of asthma has intensified interest in the natural history of asthma. An improved understanding of the genetic, environmental, and developmental factors contributing to the inception and exacerbation of asthma will be crucial to efforts to devise effective preventive and therapeutic interventions. There is increasing evidence that the complex interplay of early life respiratory viral infections and allergic sensitization is important in the development of asthma. Major causes of asthma exacerbations are respiratory viral infections and aeroallergen exposure, which may have interactive co-morbid effects. This review describes the potential role of thymic stromal lymphopoietin (TSLP) as a connection between the innate immune response to respiratory viral infections and the type-2 adaptive immune response in the development and exacerbation of asthma.

Pentoxifylline inhibits Vgamma9/Vdelta2 T lymphocyte activation of patients with active Behçets disease in vitro

The aim of this study is to evaluate the in vitro effect of pentoxifylline (PTX) on T Vgamma9/Vdelta2 lymphocyte function in Behçets disease (BD). We investigated the effect of PTX on Vgamma9/Vdelta2 T cell expansion and expression of TNFRII receptor and perforin content before and after PTX addition by means of FACS analysis lymphocyte cultures from patients with active and inactive BD and healthy subjects. The addition of PTX at a concentration of 1 mg/ml determined a significant inhibition of cell expansion, a down regulation of TNF receptor expression and inhibited the PMA-induced degranulation of perforin. Taken together these data indicate that PTX is capable of interfering with Vgamma9/Vdelta2 T cell function in BD, and although cell culture models cannot reliably predict all of the potential effects of the drug in vivo, our results encourage the possibility that this drug may find use in a range of immunological disorder characterized by dysregulated cell-mediated immunity.

Nitric oxide production in mouse and rat macrophages: A rapid and efficient assay for screening of drugs immunostimulatory effects in human cells

Activation of inducible nitric oxide (NO) synthase (iNOS) and resulting high-output NO release is known to depend on the action of cytokines. We investigated in vitro production of NO by resident peritoneal macrophages from mice and rats, and secretion of cytokines by these cells as well as by human peripheral blood mononuclear cells (PBMC). The cells were cultured in the presence of a selected group of acyclic nucleoside phosphonates that have previously been shown to possess immunobiological potential. Several of the compounds enhanced production of NO in animal macrophages. This activity was associated with stimulatory effects on secretion of cytokines such as TNF-alpha in all mouse and rat macrophages and human PBMC, and IL-10 in mouse and human cells. Statistically highly significant correlation between the range of NO biosynthesis in rodent cells and extent of cytokine stimulation in human PBMC has been observed. It is suggested that the NO assay may be regarded as an efficient, economical and relatively reliable tool in primary screening for intrinsic immunostimulatory activity of compounds in human cell system, at least from the point of view of cytokine secretion.

Cholera toxin transiently inhibits porcine T cell proliferation in vitro

Cholera toxin (Ctx) is an important mucosal adjuvant with potential experimental applications in pigs. However, little is known about the direct effects of Ctx on porcine immune cells. Therefore, we analysed the influence of Ctx on mitogen-induced lymphocyte proliferation. Ctx inhibited peripheral blood mononuclear cell (PBMC) proliferation with an IC50 of 34+/-17 ng/mL. This inhibition was not due to increased cell death. Lymphoblast formation in cultures stimulated with concanavalin A and Ctx was decreased at 24 h, but had reached the levels of control cultures again at 72 and 120 h, indicating that suppression was transient. Analysis of T cell subsets revealed that Ctx treatment specifically reduced the percentage of CD4-CD8+ and gammadelta T cells, whereas the proportion of CD4+CD8- increased. Furthermore, Ctx caused secretion of IL-10 by PBMC cultures, but depressed TNFalpha secretion.

Involvement of tyrosine kinases and MAP kinases in the production of TNF-alpha and IL-1beta by macrophages in vitro on treatment with phytohemagglutinin

Treatment of murine peritoneal macrophages with various doses of phytohemagglutinin (PHA) for different time intervals enhanced production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). Maximum transcription for TNF-alpha and IL-1beta was observed at 16 h, whereas maximum production was observed at 24 h of PHA treatment. The most optimum dose was 1 mug/mL PHA. Pharmacologic inhibitors of tyrosine kinase, p42/44, p38, and JNK downregulate the PHA-induced expression of TNF-alpha and IL-1beta. Maximum protein tyrosine kinase (PTK) activity in macrophages was seen at 5 min of PHA-treatment. PHA-treated macrophages showed maximum expression of phospho-p42/44 and phospho-JNK at 15 min. It was also observed that p38 is activated after 12 h of PHA treatment. Pharmacologic inhibitor of tyrosine kinase, genistein down-regulated the PHA-induced activation of p42/44 and JNK.

Differential activation of macrophages in vitro by lectin Concanavalin A, Phytohemagglutinin and Wheat germ agglutinin: production and regulation of nitric oxide

The role of Concanavalin A (ConA), Phytohemagglutinin (PHA) and Wheat germ agglutinin (WGA) in the activation of murine peritoneal macrophages particularly with reference to production and regulation of nitric oxide (NO) has been investigated. Macrophages on treatment with ConA and PHA showed significantly enhanced production of NO, which was dose and time dependent. On the other hand macrophages treated with WGA did not produce NO. L-N-monomethyal-l-arginine (L-NMMA), an inhibitor of NOS inhibited the ConA and PHA induced NO production. ConA and PHA treatment of macrophages induced transcription of iNOS gene and the enhanced expression of iNOS protein. Pharmacological inhibitors of PI3 kinase-Wortmannin, tyrosine kinase-Genestein, protein kinase C-H-7 and p42/44-PD98059 inhibited the ConA and PHA induced production of NO and p38 MAP kinase inhibitor SB202190 inhibited NO production only in ConA treated macrophage, while Galphai protein inhibitor-PTX and JNK inhibitor-SP600125 inhibited NO production in PHA treated macrophages. Tyrophostin (AG490), an inhibitor of JAK2 and TMB-8, an intracellular calcium immobilizing agent also inhibited the ConA and PHA induced NO production, suggesting the involvement of JAK-STAT pathway and calcium. The data also provides the relative measure and importance of different key signaling molecules in the regulation of NO production by macrophages on activation.

Dual ligand stimulation of RAW 264.7 cells uncovers feedback mechanisms that regulate TLR-mediated gene expression

To characterize how signaling by TLR ligands can be modulated by non-TLR ligands, murine RAW 264.7 cells were treated with LPS, IFN-gamma, 2-methyl-thio-ATP (2MA), PGE(2), and isoproterenol (ISO). Ligands were applied individually and in combination with LPS, for 1, 2, and 4 h, and transcriptional changes were measured using customized oligo arrays. We used nonadditive transcriptional responses to dual ligands (responses that were reproducibly greater or less than the expected additive responses) as a measure of pathway interaction. Our analysis suggests that cross-talk is limited; <24% of the features with significant responses to the single ligands responded nonadditively to a dual ligand pair. PGE(2) and ISO mainly attenuated, while 2MA enhanced, LPS-induced transcriptional changes. IFN-gamma and LPS cross-regulated the transcriptional response induced by each other: while LPS preferentially enhanced IFN-gamma-induced changes in gene expression at 1 h, IFN-gamma signaling primarily attenuated LPS-induced changes at 4 h. Our data suggest specific cross-talk mechanisms: 1) LPS enhances the expression of IFN-gamma-response genes by augmenting STAT1 activity and by activating NF-kappaB, which synergizes with IFN-gamma-induced transcriptional factors; 2) IFN-gamma attenuates the late LPS transcriptional response by increasing the expression of suppressor of cytokine signaling 1 and cytokine-inducible SH2-containing protein expression; 3) 2MA modulates LPS secondary transcriptional response by increasing IFN-beta and inhibiting IL-10 gene expression; 4) PGE(2) and ISO similarly regulate the LPS transcriptional response. They increase IL-10 transcription, resulting in attenuated expression of known IL-10-suppressed genes.

Dietary intake in sensitized children with recurrent wheeze and healthy controls: a nested case-control study

BACKGROUND

The rising prevalence of asthma and allergic disease remains unexplained. Several risk factors have been implicated including diet, in particular poly-unsaturated fats and antioxidant intake.

METHODS

A nested case-control study comparing the dietary intake of sensitized children with recurrent wheeze (age 3-5 years) and nonsensitized children who had never wheezed was carried out within an unselected population-based cohort. Cases and controls were matched for age, sex, parental atopy, indoor allergen exposure and pet ownership. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire and nutrient analysis program.

RESULTS

Thirty-seven case-control pairs (23 male, mean age 4.4 years) participated. Daily total polyunsaturated fat intake was significantly higher in sensitized wheezers (g/day, geometric mean, 95% confidence intervals: 7.1, 6.4-7.9) compared with nonsensitized nonwheezy children (5.6, 5.0-6.3, P = 0.003). Daily omega-3 and omega-6 fat intakes were not significantly different between the two groups. No significant differences were found in intake of any antioxidant or antioxidant cofactors between the groups.

CONCLUSIONS

Young sensitized wheezy children had a significantly higher total polyunsaturated fat intake compared with nonsensitized nonwheezy children. However, we were unable to distinguish a significant difference in specific poly-unsaturated fat intakes. Otherwise the children in both groups had a very similar nutritional intake.

Beta-agonists modulate T-cell functions via direct actions on type 1 and type 2 cells

Although the beta2-adrenergic receptor (beta2AR) is the most extensively characterized G-protein-coupled receptor (GPCR), the effects of beta-agonists on T-cell subtype function remain poorly understood. In contrast to studies suggesting lack of beta2AR expression on type 2 T cells, we demonstrate that type 2 interleukin-13+ (IL-13+) T cells (CD4+ or CD8+) in human peripheral blood lymphocytes (PBLs) can respond directly to beta-agonist, with effects including induction of protein kinase A (PKA) activity and associated inhibition of CD3-stimulated CD25 expression; CD3-stimulated IL-13, interferon-gamma (IFN-gamma), and IL-2 production; and p38 mitogen-activated protein kinase (MAPK) phosphorylation. PGE2 was more efficacious than beta-agonist in activating PKA and inhibiting cytokine production. beta-agonist and PGE2 also inhibited phorbol myristate acetate (PMA) + calcimycin-stimulated IFN-gamma and IL-2 (but not IL-13) production, suggesting that upstream CD3-initiated signaling is not the sole locus of PKA actions. Differential regulation of PMA-stimulated p38, p42/p44, and NF-kappaB explained the capacity of PGE2 and beta-agonist to inhibit IFN-gamma but not IL-13 production. The inhibition of CD3 + CD28-stimulated IL-13 production by both beta-agonist and PGE2 was reversed at low agonist concentrations, resulting in enhanced IL-13, but not IFN-gamma or IL-2, production. These findings identify direct effects of beta2AR activation on T-cell subtypes and suggest a complex role for GPCRs and PKA activity in modulating T-cell functions.

The negative immunoregulatory effects of fluoxetine in relation to the cAMP-dependent PKA pathway

Recently, we have shown that various types of antidepressants, including selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, have negative immunoregulatory effects. These antidepressants suppress the interferon-gamma (IFN-gamma)/interleukin-10 (IL-10) production ratio, which is of critical importance for the determination of the capacity of immunocytes to inhibit or activate monocytic/lymphocytic functions. Since cyclic adenosine monophosphate (cAMP) production is stimulated by some antidepressants, and since cAMP inhibits IFN-gamma and stimulates IL-10 production, we postulate that the negative immunoregulatory effects of antidepressants result from their effects on the cAMP-dependent protein kinase A (PKA) pathway. The aim of the present study was to determine whether the negative immunoregulatory effects of fluoxetine may be blocked by antagonists of the cAMP-dependent PKA pathway, such as, e.g., SQ 22536, an adenylate cyclase inhibitor, and Rp-8-Br-cAMPs (Rp-isomer of 8-bromo-adenosine-3',5'-monophosphorothioate), a PKA antagonist. To this end, diluted whole blood collected from 17 normal volunteers was incubated with fluoxetine (10(-6) and 10(-5) M), with or without SQ 22536 (10(-6) and 10(-4) M) and Rp-8-Br-cAMPs (10(-6) and 10(-4) M), afterwards, IFN-gamma, IL-10 and the tumor necrosis factor alpha (TNF-alpha) were determined. Fluoxetine, 10(-6) and 10(-5) M, significantly reduced the production of IFN-gamma and TNF-alpha, and significantly decreased the IFN-gamma/IL-10 production ratio. SQ 22536 and Rp-8-Br-cAMPs were unable to block the suppressant effects of fluoxetine on the IFN-gamma/IL-10 ratio. Rp-8-Br-cAMPs, 10(-4), but not 10(-6) M, normalized the fluoxetine-induced suppression of TNF-alpha production. It is concluded that the suppressant effect of fluoxetine on the IFN-gamma/IL-10 production ratio is probably not related to the induction of the cAMP-dependent PKA pathway, whereas the suppressant effect on TNF-alpha may be related to the induction of PKA. The obtained results suggest that increased activation of the PKA-dependent pathway may constitute an important molecular basis for some (suppression of TNF-alpha production), but not all (suppression of IFN-gamma production), negative immunoregulatory effects of fluoxetine.