TH2 cells in allergic inflammation: a target of immunotherapy

Importance of glial activation in neuropathic pain

Glia plays a crucial role in the maintenance of neuronal homeostasis in the central nervous system. The microglial production of immune factors is believed to play an important role in nociceptive transmission. Pain may now be considered a neuro-immune disorder, since it is known that the activation of immune and immune-like glial cells in the dorsal root ganglia and spinal cord results in the release of both pro- and anti-inflammatory cytokines, as well as algesic and analgesic mediators. In this review we presented an important role of cytokines (IL-1alfa, IL-1beta, IL-2, IL-4, IL-6, IL-10, IL-15, IL-18, TNFalpha, IFNgamma, TGF-beta 1, fractalkine and CCL2); complement components (C1q, C3, C5); metaloproteinases (MMP-2,-9) and many other factors, which become activated on spinal cord and DRG level under neuropathic pain. We discussed the role of the immune system in modulating chronic pain. At present, unsatisfactory treatment of neuropathic pain will seek alternative targets for new drugs and it is possible that anti-inflammatory factors like IL-10, IL-4, IL-1alpha, TGF-beta 1 would fulfill this role. Another novel approach for controlling neuropathic pain can be pharmacological attenuation of glial and immune cell activation. It has been found that propentofylline, pentoxifylline, minocycline and fluorocitrate suppress the development of neuropathic pain. The other way of pain control can be the decrease of pro-nociceptive agents like transcription factor synthesis (NF-kappaB, AP-1); kinase synthesis (MEK, p38MAPK, JNK) and protease activation (cathepsin S, MMP9, MMP2). Additionally, since it is known that the opioid-induced glial activation opposes opioid analgesia, some glial inhibitors, which are safe and clinically well tolerated, are proposed as potential useful ko-analgesic agents for opioid treatment of neuropathic pain. This review pointed to some important mechanisms underlying the development of neuropathic pain, which led to identify some possible new approaches to the treatment of neuropathic pain, based on the more comprehensive knowledge of the interaction between the nervous system and glial and immune cells.

Cytokine expression in the epidural space: a model of noncompressive disc herniation-induced inflammation

STUDY DESIGN

Animal study.

OBJECTIVE

Development of an animal model for the study of biochemical changes that occur in the epidural space after intervertebral disc herniation.

SUMMARY OF BACKGROUND DATA

Although strong evidence for an inflammatory component exists, the biochemical processes underlying pain after disc herniation remain unknown.

METHODS

Epidural lavage was performed in 48 rats after L5 dorsal root ganglion exposure at baseline and 3, 6, or 24 hours after placement of autologous nucleus pulposus (NP) (N = 15), saline (N = 15), or NP + an interferon-γ antibody (anti-IFN-γ; N = 18) directly onto the dorsal root ganglion. Multiplex assays quantifying interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor α (TNF-α), IFN-γ, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were performed. NP (N = 7) was also analyzed for these cytokines by placing NP into saline and measuring the relative concentration.

RESULTS

Cytokines measured low at baseline (0-100 pg/mL) in all groups. Compared with saline, NP application caused IL-6 elevation, peaking at T = 3 hours, that was prevented by anti-IFN-γ. NP induced elevation of TNF-α, peaking at T = 24 hours and was prevented by anti-IFN-γ. IFN-γ was elevated after NP at T = 3 hours and T = 24 hours. IL-1α was similar after saline versus NP. The concentrations of IL-1β and IL-10 were elevated at T = 3 hours, 6 hours, and 24 hours in all groups without between-groups difference. The level of IL-4 peaked at T = 3 hours in the NP group and was different than saline and NP + anti-IFN-γ groups, but the time effect was insignificant. There was no change for GM-CSF. The concentration of cytokines measured in normal NP was less than 2 pg/mL for all cytokines except TNF-α.

CONCLUSION

In this model of acute noncompressive disc herniation, NP caused the elevation of epidural IL-6, TNF-α, and IFN-γ--all attenuated by IFN-γ blockade. IL-1β and IL-10 were both significantly elevated by saline alone and their response was not prevented by IFN-γ blockade. This model may prove useful for the study of the biochemical processes by which NP induces inflammation-induced nerve root irritation and radiculopathic pain.

Interleukin-4 modulates the inflammatory response in ifosfamide-induced hemorrhagic cystitis

We investigated whether interleukin-4 (IL-4) is present and capable of reducing inflammatory changes seen in ifosfamide-induced hemorrhagic cystitis. Male Swiss mice were treated with saline or ifosfamide alone or ifosfamide with the classical protocol with mesna and analyzed by changes in bladder wet weight (BWW), macroscopic and microscopic parameters, exudate, and hemoglobin quantification. In other groups, IL-4 was administered intraperitoneally 1 h before ifosfamide. In other experimental groups, C57BL/6 WT (wild type) and C57BL/6 WT IL-4 (-/-) knockout animals were treated with ifosfamide and analyzed for changes in BWW. Quantification of bladder IL-4 protein by ELISA in control, ifosfamide-, and mesna-treated groups was performed. Immunohistochemistry to tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) as well as protein identification by Western blot assay for inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was carried out on ifosfamide- and IL-4-treated animals. In other experimental groups, antiserum against IL-4 was given 30 min before ifosfamide. In IL-4-treated animals, the severity of hemorrhagic cystitis was significantly milder than in animals treated with ifosfamide only, an effect that was reverted with serum anti-IL-4. Moreover, knockout animals for IL-4 (-/-) exhibit a worse degree of inflammation when compared to C57BL/6 wild type. Exogenous IL-4 also attenuated TNF-α, IL-1β, iNOS, and COX-2 expressions in ifosfamide-treated bladders. IL-4, an anti-inflammatory cytokine, attenuates the inflammation seen in ifosfamide-induced hemorrhagic cystitis.

In vivo anti-inflammatory and analgesic activities of a purified saponin fraction derived from the root of Ilex pubescens

The root of Ilex pubescens (Mao-Dong-Qing in Chinese, MDQ) has been commonly used for treatment of cardiovascular and inflammatory diseases in the Chinese medical system. The current studies aimed to investigate the anti-inflammatory and analgesic effects as well as the underlying mechanisms of a purified saponin fraction (PSF) derived from MDQ. PSF was found to significantly suppress the paw edema of rats induced by histamine given intraperitoneally at dosages ranging from 12.5-100 mg/kg. Meanwhile, PSF given orally at dosages of 200 and 100 mg/kg significantly inhibited acetic acid-induced abdominal writhing response of mice and prolonged the time required for mouse tail flick after exposure to a source of radiant heat. The mechanistic studies showed that cyclooxygenase-2 (COX-2) protein expression in carrageenan-injected paw tissues of rats was markedly attenuated by intraperitoneal injection of PSF at dosages of 12.5 to 100 mg/kg. PSF could also markedly inhibit production of proinflammatory cytokines, especially IL-1 beta, IL-6 and TNF-alpha, but enhance production of anti-inflammatory cytokines of IL-4 and IL-10 in the carrageenan-injected paw tissues in rats. These effects resulted in an overall attenuation of the ratio of proinflammatory/anti-inflammatory cytokines and, ultimately suppression of the paw edema. In conclusion, the current study has demonstrated the in vivo anti-inflammatory and analgesic effects of PSF, and suggested that the molecular mechanisms might be associated with inhibition of the elevated expression of COX-2 protein and the overproduction of the proinflammatory cytokines, as well as augmentation of the anti-inflammatory cytokines IL-4 and IL-10 in the carrageenan-injected paw tissues of rats.

Operação do refluxo gastro-esofágico isolada ou associada à colecistectomia: avaliação do estresse cirúrgico pela dosagem hormonal e de citocinas

OBJETIVO: O objetivo do presente estudo é comparar o estresse cirúrgico por meio de dosagens hormonais (ACTH e cortisol) e de citocinas (IL-4, IL-10, TNF-a, e IFN-g), em pacientes que foram submetidos somente à operação da transição esofagogástrica com aqueles submetidos à operação da transição esofagogástrica associada à colecistectomia. MÉTODO: Foram estudados 31 pacientes , sendo 19 submetidos à operação da transição esofagogástrica e 12, que apresentavam associação de colelitíase, foram submetidos à colecistectomia e à operação da transição esofagogástrica. A coleta do sangue foi realizada no pré operatório e às 24, 48 e 72 horas no período pós-operatório. Foram realizadas as dosagens de hormônios (ACTH e cortisol) e citocinas (IL-4, IL-10, TNF-a e IFN-g). As variáveis contínuas foram submetidas a teste de normalidade. Foram aplicados testes não paramétricos Mann-Whitney, com significância estabelecida a p<0,05. RESULTADOS: Quanto ao ACTH, os valores foram maiores no grupo 1, às 24 e 48 horas. Na análise do cortisol, TNF-a, IFN-g, IL-4 e IL-10, verificou-se que os valores foram maiores no grupo 2, às 24 e 48 horas. Não se verificou diferença estatisticamente significativa entre os grupos em quaisquer dos tempos de análise. CONCLUSÕES: Com base neste material, pode-se inferir que associar a colecistectomia à operação da transição esofagogástrica não aumenta o stresse cirúrgico, mensurado pelo ACTH, cortisol e citocinas (TNF- a, INF-g, IL-4 e IL-10).

In vitro and in vivo anti-inflammatory activity of the new glucocorticoid ciclesonide

The glucocorticoid ciclesonide is the 2'R-epimer of 2'-cyclohexyl-11beta-hydroxy-21-isobutyryloxy-16bH-dioxolo[5',4':16,17]pregna-1,4-diene-3,20-dione. The active metabolite desisobutyryl-ciclesonide (des-CIC) is derived from ciclesonide by esterase cleavage of isobutyrate at the C21 position. The relative binding affinities at the rat glucocorticoid receptor were dexamethasone, 100; ciclesonide, 12; des-CIC, 1212; and budesonide, 905. Des-CIC potently inhibited the activation of murine and human lymphocytes in a series of different in vitro systems. With the exception of concanavalin A-stimulated rat spleen cells, des-CIC was more potent than the parent compound. Des-CIC compared well with budesonide in all in vitro systems. Furthermore, the respective 2'S-epimers were always significantly less potent than the 2'R-epimers. In vivo, ciclesonide (intratracheal administration), des-CIC, and budesonide inhibited antigen-induced accumulation of eosinophils, protein, and tumor necrosis factor-alpha into the bronchoalveolar lavage fluid of ovalbumin-sensitized and -challenged Brown Norway rats with an ED(50) value ranging from 0.4 to 1.3 mg/kg, indicating similar potency, which suggests in vivo activation of the parent compound. Ciclesonide and budesonide inhibited the bradykinin-induced protein leakage into the rat trachea. In the rat cotton pellet model, ciclesonide inhibited granuloma formation (ED(50):= of 2 microg/pellet), whereas budesonide and des-CIC were 15- and 20-fold less active; thymus involution was induced with an ED(50) of 303, 279, and 154 microg/pellet, respectively. When applied orally to rats for 28 days, ciclesonide showed low potency in reducing weight of thymus and adrenals, suggesting low oral bioavailability. The in vivo data on ciclesonide highlight its effective local action and a reduced potential for side effects.

The role of lymphocytes in allergic disease

In the last few years strong evidence has accumulated to suggest that allergen-reactive type-2 T helper (T(H)2) cells play an important role in the induction and maintenance of the allergic inflammatory cascade. First, cytokines and chemokines produced by T(H)2 cells (GM-CSF, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, macrophage-derived chemokine) and those produced by other cell types in response to T(H)2 cytokines or as a reaction to T(H)2-related tissue damage (eotaxin, transforming growth factor-beta, IL-11) account for most pathophysiologic aspects of allergic disorders (production of IgE antibodies; recruitment or activation of mast cells, basophils, and eosinophils; mucus hypersecretion; subepithelial fibrosis; and tissue remodeling). The T(H)2 hypothesis may also explain the complex genetic background responsible for allergic disorders. Several genes are involved in the development and regulation of T(H)2 cells and may provide the reason why the prevalence of atopic allergy is increasing in Western countries. Indeed, a dramatic change has occurred in the last several decades in the "microbial" environment of children, thus probably altering the balance between T(H)1 and T(H)2 responses to "innocuous" antigens (allergens) in favor of T(H)2 responses. Finally, the T(H)2 hypothesis offers exciting opportunities for the development of novel immunotherapeutic strategies targeted to address allergen-specific T(H)2 cells or T(H)2-derived effector molecules in atopic individuals.

Th1/Th2 cells

A large body of evidence indicates the existence of functionally polarized CD4+ T-cell responses based on their profile of cytokine secretion. Type 1 T helper (Th1) cells produce interferon-gamma, interleukin (IL)-2, and tumour necrosis factor (TNF)-beta, which activate macrophages and are responsible for cell-mediated immunity and phagocyte-dependent protective responses. By contrast, type 2 Th (Th2) cells produce IL-4, IL-5, IL-10, and IL-13, which are responsible for strong antibody production, eosinophil activation, and inhibition of several macrophage functions, thus providing phagocyte-independent protective responses. Th1 cells mainly develop following infections by intracellular bacteria and some viruses, whereas Th2 cells predominate in response to infestations by gastrointestinal nematodes. Polarized Th1 and Th2 cells not only exhibit different functional properties, but also show the preferential expression of some activation markers and distinct transcription factors. Several mechanisms may influence the Th cell differentiation, which include the cytokine profile of "natural immunity" evoked by different offending agents, the nature of the peptide ligand, as well as the activity of some costimulatory molecules and microenvironmentally secreted hormones, in the context of the individual genetic background. In addition to playing different roles in protection, polarized Th1-type and Th2-type responses are also responsible for different types of immunopathological reactions. Th1 cells are involved in the pathogenesis of organ-specific autoimmune disorders, Crohn's disease, Helicobacter pylori-induced peptic ulcer, acute kidney allograft rejection, and unexplained recurrent abortions. In contrast, allergen-specific Th2 responses are responsible for atopic disorders in genetically susceptible individuals. Moreover, Th2 responses against still unknown antigens predominate in Omenn's syndrome, idiopathic pulmonary fibrosis, and progressive systemic sclerosis. Finally, the prevalence of Th2 responses may play some role in a more rapid evolution of human immunodeficiency virus infection to the full-blown disease. The Th1/Th2 paradigm also provides the rationale for the development of new types of vaccines against infectious agents and of novel strategies for the therapy of allergic and autoimmune disorders.

The pathogenesis and control of diarrhoea and breech soiling in adult Merino sheep

Diarrhoea and soiling of the breech with faeces ('winter scours') is a serious problem in adult Merino sheep grazing improved pastures in south-eastern Australia during winter and spring. This occurs even on farms where gastro-intestinal nematodes are effectively controlled. It was shown that winter scours was associated with the ingestion of trichostrongylid larvae, and that host factors were important in determining susceptibility to this syndrome. No differences were detected in the protective immune response of affected and unaffected sheep to gut nematodes. However, affected sheep had a hypersensitive inflammatory reaction in the pylorus and upper jejunum, characterised by the infiltration of significantly more eosinophils and changed lymphocyte populations. The changes in the lymphocyte populations included a reduced number of CD8+ cells, increased CD4+:CD8+ T-cell ratio, and significantly reduced numbers of cells reacting to interferon-gamma. High doses of infective larvae (20,000/week of Ostertagia circumcincta and Trichostrongylus vitrinus) did not induce diarrhoea in sheep not susceptible to winter scours. In contrast, only low doses (2000/week) initiated scouring in sheep selected as being susceptible to winter scours. Therefore, even considerably improved worm control programmes, including the selection of sheep with increased resistance to gut nematodes, will not prevent winter scours. Rather, phenotypic culling and genetic selection, to remove sheep susceptible to the hypersensitivity inflammatory response, is proposed as the most suitable long-term control strategy.

Cytokine-mediated inflammatory hyperalgesia limited by interleukin-4

1. The effect of IL-4 on responses to intraplantar (i.pl.) carrageenin, bradykinin, TNFalpha, IL-1beta, IL-8 and PGE2 was investigated in a model of mechanical hyperalgesia in rats. Also, the cellular source of the IL-4 was investigated. 2. IL-4, 30 min before the stimulus, inhibited responses to carrageenin, bradykinin, and TNFalpha, but not responses to IL-1beta, IL-8 and PGE2. 3. IL-4, 2 h before the injection of IL-1beta, did not affect the response to IL-1beta, whereas IL-4, 12 or 12+2 h before the IL-1beta, inhibited the hyperalgesia (-30%, -74%, respectively). 4. In murine peritoneal macrophages, murine IL-4 for 2 h before stimulation with LPS, inhibited (-40%) the production of IL-1beta but not PGE2. Murine IL-4 (for 16 h before stimulation with LPS) inhibited LPS-stimulated PGE2 but not IL-1beta. 5. Anti-murine IL-4 antibodies potentiated responses to carrageenin, bradykinin and TNFalpha, but not IL-1beta and IL-8, as well as responses to bradykinin in athymic rats but not in rats depleted of mast cells with compound 40/80. 6. These data suggest that IL-4 released by mast cells limits inflammatory hyperalgesia. During the early phase of the inflammatory response the mode of action of the IL-4 appears to be inhibition of the production TNFalpha, IL-1beta and IL-8. In the later phase of the response, in addition to inhibiting the production of pro-inflammatory cytokines, IL-4 also may inhibit the release of PGs.

Intralesional cytokines in chronic oxazolone-induced contact sensitivity suggest roles for tumor necrosis factor alpha and interleukin-4

An analysis was conducted of the cytokine profile and inflammatory response in oxazolone sensitized mouse skin. Following exposure to oxazolone, the intralesional production of inflammatory cytokines was demonstrable at the levels of both mRNA and protein. An initial challenge led to a transient increase in tumor necrosis factor-alpha production followed predominately by the T helper (Th)1 cytokine, interferon-gamma. There was a minimal production of interleukin-4, a Th2 cytokine. Continued exposure to oxazolone led to a downregulation of interferon-gamma and an upregulation of interleukin-4 production. A strong relationship was found between interleukin-4 and the inflammatory response, as measured by ear thickness. Similar experiments conducted in mast cell-deficient mice revealed reduced neutrophil influx but only minor changes in cytokine profile. An irritant response induced by chronic exposure of mouse skin to phorbol ester did not reveal any significant interferon-gamma or interleukin-4 response but was characterized by a tumor necrosis factor-alpha response that correlated with the inflammatory response. These observations suggest that the major source of interferon-gamma and interleukin-4 in the oxazolone response may be the infiltrating lymphocytes; whereas the tumor necrosis factor-alpha may result from the local irritation seen with both oxazolone and phorbol ester. At the end of 4 wk of chronic exposure to oxazolone, it was found that serum IgE levels had significantly increased. Histologic analysis of the skin lesion revealed that a mixed infiltrate including eosinophils developed upon repeat exposure to oxazolone. These findings are consistent with an early predominate Th1 response that is reduced and largely replaced with a Th2 response upon chronic T cell activation.

The TH1/TH2 paradigm in allergy

Recent evidence has been accumulated to suggest that allergen-reactive type 2 helper T cells (Th2) play a triggering role in the activation and/or recruitment of IgE antibody-producing B cells, mast cells and eosinophils, i.e. the cellular triad involved in the allergic inflammation. Interleukin (IL)-4 production by a still unknown cell type (T cell subset, mast cell/basophil?) at the time of antigen presentation to the Th cell is critical for the development of Th2 cells. Other cytokines, such as IL-1 and IL-10, and hormones, such as calcitriol and progesterone, also play a favoring role. In contrast, cytokines such as interferon (IFN-alpha, IFN-gamma, IL-12 and transforming growth factor (TGF)-beta, and hormones, play a negative regulatory role on the development of Th2 cells. However, the mechanisms underlying the preferential activation by environmental allergens of Th2 cells in atopic individuals still remain obscure. Some gene products selectively expressed in Th2 cells or selectively controlling the expression of IL-4 have recently been described. Moreover, cytokines and other gene products that dampen the production of IL-4, as well as the development and/or the function of Th2 cells, have been identified. These findings allow us to suggest that the up-regulation of genes controlling IL-4 expression and/or abnormalities of regulatory mechanisms of Th2 development and/or function may be responsible for Th2 responses against common environmental allergens in atopic people. The new insights in the pathophysiology of T cell responses in atopic diseases provide exciting opportunities for the development of novel immunotherapeutic strategies. They include the induction of nonresponsiveness in allergen-specific Th2 cells by allergen peptides or redirection of allergen-specific Th2 responses by Th1-inducing cytokines, altered peptide ligands, allergens incorporated into recombinant microorganisms or bound to appropriate adjuvants, and plasmid DNA vaccination. In severe atopic patients, the possibility of nonallergen-specific immunotherapeutic regimens designed to target Th2 cells or Th2-dependent effector molecules, such as specific IL-4 transcription factors, IL-4, IL-5 and IgE, may also be suggested.