Interleukin-6 is released in the cutaneous response to allergen challenge in atopic individuals

Th2 Modulation of Transient Receptor Potential Channels: An Unmet Therapeutic Intervention for Atopic Dermatitis

Atopic dermatitis (AD) is a multifaceted, chronic relapsing inflammatory skin disease that affects people of all ages. It is characterized by chronic eczema, constant pruritus, and severe discomfort. AD often progresses from mild annoyance to intractable pruritic inflammatory lesions associated with exacerbated skin sensitivity. The T helper-2 (Th2) response is mainly linked to the acute and subacute phase, whereas Th1 response has been associated in addition with the chronic phase. IL-17, IL-22, TSLP, and IL-31 also play a role in AD. Transient receptor potential (TRP) cation channels play a significant role in neuroinflammation, itch and pain, indicating neuroimmune circuits in AD. However, the Th2-driven cutaneous sensitization of TRP channels is underappreciated. Emerging findings suggest that critical Th2-related cytokines cause potentiation of TRP channels, thereby exaggerating inflammation and itch sensation. Evidence involves the following: (i) IL-13 enhances TRPV1 and TRPA1 transcription levels; (ii) IL-31 sensitizes TRPV1 via transcriptional and channel modulation, and indirectly modulates TRPV3 in keratinocytes; (iii) The Th2-cytokine TSLP increases TRPA1 synthesis in sensory neurons. These changes could be further enhanced by other Th2 cytokines, including IL-4, IL-25, and IL-33, which are inducers for IL-13, IL-31, or TSLP in skin. Taken together, this review highlights that Th2 cytokines potentiate TRP channels through diverse mechanisms under different inflammatory and pruritic conditions, and link this effect to distinct signaling cascades in AD. This review strengthens the notion that interrupting Th2-driven modulation of TRP channels will inhibit transition from acute to chronic AD, thereby aiding the development of effective therapeutics and treatment optimization.

JAK1/2 inhibition impairs the development and function of inflammatory dendritic epidermal cells in atopic dermatitis

BACKGROUND

Janus kinase (JAK) inhibitors are a new class of therapeutic compounds for dermatological diseases. In atopic dermatitis (AD), data of clinical phase III trials show rapid improvement of pruritus and significant reduction of inflammation within the first weeks with a favorable safety profile. However, their mode of action in AD is not fully understood.

OBJECTIVES

In our study, we investigate the effect of different JAK inhibitors on cell differentiation, phenotype, and function of inflammatory dendritic epidermal cells (IDECs).

METHODS

We analyzed the JAK expression in IDEC from ex vivo skin and in vitro generated IDECs using flow cytometry and PCR. Further, we studied in vitro the effect of different JAK inhibitors on IDEC cell differentiation, phenotype, and maturation.

RESULTS

IDECs express JAK1 and JAK2 ex vivo and in vitro. We found that JAK1 and JAK2 were upregulated during the differentiation from monocytes to IDECs. Conversely, JAK2 inhibition by ruxolitinib (JAK1/2 inhibitor) or BMS-911543 (JAK2 inhibitor) abrogated the differentiation from monocytes into IDECs. Differentiated IDECs can redifferentiate into a more monocyte-like phenotype in the presence of ruxolitinib or BMS-911543. Furthermore, we showed that concomitant inhibition of JAK1/2 rather than blocking JAK1 or JAK2 alone, impaired maturation and the release of proinflammatory cytokines on lipopolysaccharide stimulation.

CONCLUSIONS

Our results suggest that inhibition of JAK1/2 impairs IDEC differentiation and function. We provide new insight into the mode of action of JAK inhibitors in AD and highlight the role of JAK1/2 inhibitors for the treatment of patients with AD.

Association of interleukin-6 and tumor necrosis factor-α with mortality in hospitalized patients with cancer

BACKGROUND

Severe cutaneous adverse reactions (SCARs) are associated with high morbidity and mortality in patients with cancer. Early identification and treatment of SCARs may improve outcomes.

OBJECTIVE

To identify biomarkers to predict outcomes in hospitalized patients with cancer who developed SCARs.

METHODS

Retrospective review of 144 hospitalized patients with cancer with a morbilliform rash, recorded testing for serum cytokines (interleukin [IL]-6, IL-10, and tumor necrosis factor [TNF]-α) or elafin, and a dermatology consultation. Rashes were categorized as simple morbilliform rash without systemic involvement or complex morbilliform rash with systemic involvement.

RESULTS

Fifty-four of 144 (37.5%) patients died during follow-up. Elevated levels of IL-6, IL-10, and TNF-α were associated with decreased survival. Overall survivals in patients with elevated levels of IL-6, IL-10, and TNF-α were 53.7%, 56.6%, 53.6%, respectively, compared with 85.7%, 82.5% and 83.6%, respectively, in those with lower levels. Patients with increased levels of both IL-6 and TNF-α had a nearly 6-fold increase in mortality (hazard ratio, 5.82) compared with patients with lower levels.

LIMITATIONS

Retrospective design, limited sample size, and high-risk population.

CONCLUSIONS

Hospitalized patients with cancer with rash and elevated IL-6 and TNF-α were nearly 6 times more likely to die over the course of follow-up. These biomarkers may serve as prognostic biomarkers and therapeutic targets for this high-risk population.

Mechanisms of Skin Toxicity Associated with Metabotropic Glutamate Receptor 5 Negative Allosteric Modulators

Cutaneous reactions represent one of the most common adverse drug effects observed in clinical trials leading to substantial compound attrition. Three negative allosteric modulators (NAMs) of metabotropic glutamate receptors (mGluRs), which represent an important target for neurological diseases, developed by Pfizer, were recently failed in preclinical development due to delayed type IV skin hypersensitivity observed in non-human primates (NHPs). Here we employed large-scale phenotypic profiling in standardized panels of human primary cell/co-culture systems to characterize the skin toxicity mechanism(s) of mGluR5 NAMs from two different series. Investigation of a database of chemicals tested in these systems and transcriptional profiling suggested that the mechanism of toxicity may involve modulation of nuclear receptor targets RAR/RXR, and/or VDR with AhR antagonism. The studies reported here demonstrate how phenotypic profiling of preclinical drug candidates using human primary cells can provide insights into the mechanisms of toxicity and inform early drug discovery and development campaigns.

Oral administration of Lactobacillus delbrueckii subspecies bulgaricus OLL1073R-1 suppresses inflammation by decreasing interleukin-6 responses in a murine model of atopic dermatitis

The oral intake of Lactobacillus spp. can provide beneficial effects to the host by modulating the immune response. Atopic dermatitis (AD) is an allergic inflammatory disease mediated by various immune responses. In this study, we examined the effect of a Lactobacillus strain, Lactobacillus delbrueckii ssp. bulgaricus OLL1073R-1 (OLL1073R-1), on AD development in a murine model of AD that was developed by the topical application of mite antigen in NC/Nga mice. The oral intake of heat-killed OLL1073R-1 cells inhibited both the development of dermatitis and the elevation of an acute inflammation marker, serum amyloid A. Another bacterial strain, Lactobacillus rhamnosus OLL2984, exerted no inhibitory effects on dermatitis. The oral intake of heat-killed OLL1073R-1 cells also attenuated secretion of IL-6 from lymph node cells in response to mite antigen and reduced IL-6 levels in inflamed tissues, such as auricles. Production of IFN-γ or IL-4 was not influenced by OLL1073R-1 intake. We also found that inhibition of IL-6 signaling by gp130-Fc (a fusion protein consisting of the extracellular portion of glycoprotein 130 fused to the Fc region of human IgG1) markedly decreased the severity of dermatitis in NC/Nga mice. Moreover, secretion of IL-6 by lymph node cells was augmented in NC/Nga mice compared with that in BALB/c mice. These results indicate that IL-6 plays an essential role in the development of dermatitis in the NC/Nga mouse model of AD, and that OLL1073R-1 inhibits dermatitis, at least in part, by suppressing the IL-6 response.

Oral administration of glucosylceramide ameliorates inflammatory dry-skin condition in chronic oxazolone-induced irritant contact dermatitis in the mouse ear

BACKGROUND

Irritant contact dermatitis (ICD) is an inflammatory skin disease triggered by exposure to a chemical that is toxic or irritating to the skin. A major characteristic of chronic ICD is an inflammatory dry-skin condition with associated itching. Although glucosylceramide (GlcCer) is known to improve the skin barrier function, its mechanism of action is unknown.

OBJECTIVES

Using a mouse model of oxazolone-induced chronic ICD, this study investigated the effects of oral administration of GlcCer on inflammatory dry skin.

METHODS

Chronic ICD was induced by repeated application of oxazolone in mice. GlcCer was orally administered once daily throughout the elicitation phase. The beneficial efficacy of GlcCer on cutaneous inflammation was evaluated by assessing ear thickness, lymph node weight, histological findings, and mRNA expression of pro-inflammatory cytokines such as IL-1β and IL-6. Additionally, parameters of the itch-associated response, including scratching behavior, water content of the skin, and aquaporin-3 levels in the lesional ear, were measured.

RESULTS

Oral GlcCer administration significantly suppressed mRNA expression of the pro-inflammatory cytokines IL-1β and IL-6. GlcCer also suppressed ear swelling, lymph node weight gains, and infiltration of leukocytes and mast cells in ICD mice. In oxazolone-induced ICD mice, GlcCer significantly inhibited irritant-related scratching behavior and dehydration of the stratum corneum, and decreased aquaporin-3 expression.

CONCLUSIONS

Our results indicate that GlcCer suppressed inflammation not only by inhibiting cytokine production but also by repairing the skin barrier function, suggesting a potential beneficial role for GlcCer in the improvement of chronic ICD.

Activation of eosinophils interacting with dermal fibroblasts by pruritogenic cytokine IL-31 and alarmin IL-33: implications in atopic dermatitis

BACKGROUND

IL-31 is a pruritogenic cytokine, and IL-33 is an alarmin for damaging inflammation. They together relate to the pathogenesis of atopic dermatitis (AD). Eosinophil infiltration into the inner dermal compartment is a predominant pathological feature of AD. We herein investigated the in vitro inflammatory effects of IL-31 and IL-33 on the activation of human eosinophils and dermal fibroblasts.

METHODOLOGY/PRINCIPAL FINDINGS

Receptors, adhesion molecules and signaling molecules were assessed by Western blot or flow cytometry. Chemokines and cytokine were quantitated by multiplex assay. Functional IL-31 receptor component IL-31RA, OSMR-β and IL-33 receptor component ST2 were constitutively expressed on the surface of eosinophils. Co-culture of eosinophils and fibroblasts significantly induced pro-inflammatory cytokine IL-6 and AD-related chemokines CXCL1, CXCL10, CCL2 and CCL5. Such inductions were further enhanced with IL-31 and IL-33 stimulation. IL-31 and IL-33 could significantly provoke the release of CXCL8 from eosinophils and fibroblasts, respectively, which was further enhanced upon co-culture. In co-culture, eosinophils and fibroblasts were the main source for the release of CCL5, and IL-6, CXCL1, CXCL8, CXCL10 and CCL2, respectively. Direct interaction between eosinophils and fibroblasts was required for CXCL1, CXCL10, CXCL8 and CCL5 release. Cell surface expression of intercellular adhesion molecule-1 on eosinophils and fibroblasts was up-regulated in co-culture upon IL-31 and IL-33 stimulation. The interaction between eosinophils and fibroblasts under IL-31 and IL-33 stimulation differentially activated extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, nuclear factor-κB and phosphatidylinositol 3-kinase-Akt pathways. Using specific signaling molecule inhibitors, the differential induction of IL-31 and IL-33-mediated release of cytokines and chemokines such as IL-6 and CXCL8 from co-culture should be related to their distinct activation profile of intracellular signaling pathways.

CONCLUSIONS/SIGNIFICANCE

The above findings suggest a crucial immunopathological role of IL-31 and IL-33 in AD through the activation of eosinophils-fibroblasts interaction via differential intracellular signaling mechanisms.

What can microdialysis tell us about the temporal and spatial generation of cytokines in allergen-induced responses in human skin in vivo?

This study examined the suitability of microdialysis to assess the time course of cytokine generation from discrete sites within the skin following intradermal injection of allergen. Cytokines were recovered using two microdialysis probes, one close to the point of allergen injection and the other 1 cm away but within the area of the late-phase induration. Skin biopsies taken at both sites were stained immunocytochemically to investigate possible relationships between cytokine generation, expression of adhesion molecules, and recruitment of neutrophils and eosinophils during the late-phase allergic response. The cytokine response to probe insertion was assessed using a single probe in the opposite arm (control). At baseline, microdialysate contained low levels of IL-1alpha, IL-5, IL-8, IL-12, GM-CSF, and TNFalpha (n=27-33). At control sites, this was followed by increases in IL-6 and IL-8 at 3 and 6 hours. Allergen increased TNFalpha levels in 3/11 individuals within 30 minutes at the injection site. Levels of IL-6 and IL-8 rose rapidly and were significantly greater (P<0.05) than that of controls at 3 and 6 hours at both injection and distant sites. Adhesion molecule expression and leukocyte infiltration were elevated only at the allergen injection site, suggesting a complex relationship between cytokine generation and cellular events in allergic inflammation. In conclusion, microdialysis can be used to distinguish temporal and spatial changes in protein profiles in the skin. Furthermore, when used in conjunction with skin biopsies, it provides novel information about the mechanisms of dermal inflammation.

Cytokine expression in allergic inflammation: systematic review of in vivo challenge studies

BACKGROUND

Allergic inflammatory responses are driven by cells of the immune system that rely on cytokines to regulate the activity of other immune and structural cells.

OBJECTIVE

To review published studies to (1) identify cytokines consistently increased after allergen challenge in atopic patients and (2) investigate temporal variation in cytokine expression.

METHODS

A PUBMED systematic search was used to extract data from studies involving analysis of cytokine expression in fluids or biopsies following in vivo allergen challenge in atopic patients.

RESULTS

Data were extracted from 82 studies. There were no consistent reports of cytokine protein increase in fluids of patients at 0-1 h after challenge. At 4-12 h, the chemokines eotaxin, macrophage inflammatory protein-1alpha, RANTES (regulated on activation normal T cell expressed and secreted) and interleukin (IL)-8 have all been consistently reported to be up-regulated. At 18-24 h after challenge, the lymphokines IL-4, IL-5 and IL-13, as well as the pro-inflammatory cytokines granulocyte-macrophage colony-stimulating factor, tumour necrosis factor-alpha and IL-6 are consistently increased when compared with the respective control value. There were no reports of up-regulation in interferon-gamma protein and mRNA and in IL-2 mRNA.

CONCLUSION

The expression of granulocyte-macrophage colony-stimulating factor is consistently increased in tissues at 4-12 h after challenge. The influence of this cytokine on antigen capture and presentation by dendritic cells should be further investigated. Additionally, allergen challenge studies are needed that investigate the expression of macrophage-derived chemokine and thymus-regulated and activation-regulated chemokine in tissues of atopic patients. Blocking the effects of these lymphocyte-specific chemokines might provide new therapeutic approaches for the control of allergic inflammation.

Kinetics of gene induction after FcepsilonRI ligation of atopic monocytes identified by suppression subtractive hybridization

The high-affinity receptor for IgE, FcepsilonRI, on APCs plays an important role in the initiation and chronicity of inflammatory atopic diseases. To understand the molecular regulation of FcepsilonRI-mediated processes, differentially expressed genes are of great interest to be identified. Suppression subtractive cDNA hybridization has been used to identify genes induced after FcepsilonRI stimulation on atopic monocytes. Overexpression of the identified genes was determined by semiquantitative RT-PCR analysis of transcripts from the tester (stimulated) and driver (unstimulated) monocytes. Results were confirmed and kinetics of the transcripts established using blood cells from additional atopics at 4 and 24 h of FcepsilonRI induction. The following sequences were identified: monocyte chemoattractant protein 1, macrophage-inflammatory protein 1beta, IL-6, beta(A) subunit of inhibin/activin, IFN-stimulated gene of 54 kDa, IL-1R antagonist, and kynurenine 3-monooxygenase. Chemokines are highly expressed during the early and late phase after FcepsilonRI cross-linking, whereas proinflammatory and differentiation stimuli rapidly decline after an initial overexpression. Kynurenine 3-monooxygenase, an enzyme involved in the degradation of the amino acid tryptophan, is significantly up-regulated during the late phase after 24 h of FcepsilonRI induction. These results demonstrate that the analysis of the profile of gene induction following activation of FcepsilonRI on atopic monocytes may reveal how these cells might participate in the regulation of atopic disorders.

The ACVD task force on canine atopic dermatitis (VII): mediators of cutaneous inflammation

Controversy still exists on the role of various inflammatory mediators in the pathogenesis of canine atopic dermatitis. The objective of this article is to review the most recent information available on the inflammatory mediators that have been implicated in the pathogenesis of this disease. Studies on the role of histamine, serotonin, leukotrienes and various cytokines are presented in a comparative manner reviewing the experimental evidence for a role in the pathogenesis and the arguments against it.

Cetirizine inhibits skin reactions but not mediator release in immediate and developing late-phase allergic cutaneous reactions. A double-blind, placebo-controlled study

BACKGROUND

Recent reports have indicated cetirizine, a potent H(1)-receptor antagonist, to possess a number of anti-inflammatory effects, e.g. inhibition of mast cell degranulation and inhibition of leucocyte migration and activation.

OBJECTIVE

The aim of this study was to compare the effects of cetirizine on skin responses and mediator release in intact skin in immediate and developing late-phase allergic reactions by microdialysis technique.

METHODS

Cetirizine 10 mg once daily or matching placebo were administered to 10 atopic subjects for 6 days followed by a 2-week washout in a randomized, double-blind, placebo-controlled, cross-over trial. Immediate skin test responses to allergen, codeine, and histamine and late-phase reactions to allergen were assessed. The time course of extracellular levels of inflammatory mediators in intact skin were monitored by microdialysis techniques using 2 kDa and 3 MDa cut-off fibers, respectively.

RESULTS

Cetirizine significantly reduced immediate weal and flare reactions to allergen, codeine, and histamine. Injection of allergen, but not buffer controls, induced a significant release of histamine, tryptase, prostaglandin D(2), total protein, and eosinophilic cationic protein. No significant increase of leukotriene B(4) and myeloperoxidase was observed. Cetirizine inhibited early total protein extravasation by 40%, but this did not reach a significant level. None of the inflammatory mediators were significantly inhibited by cetirizine. Cetirizine significantly reduced the late-phase skin induration to allergen by approximately 30%.

CONCLUSION

Cetirizine potently reduced skin responses in immediate allergic reactions without inhibition of early mediators. These data indicate cetirizine to be a potent H1-receptor antagonist with no effect on mast cell activation. It did not inhibit any of the late-phase mediators, but it reduced the late skin reaction. These data suggest that mediators other than those actually measured may play a significant role in the clinical late-phase reaction.

Temporal patterns of mediator release during developing cutaneous late-phase reactions

BACKGROUND

Several inflammatory mediators have been found released in sites of cutaneous late phase reactions (LPR). However, the temporal pattern of their release during LPR development has not been characterized.

OBJECTIVE

Determine hourly accumulation of mediator release in comparison with gross and inflammatory cell responses during developing LPR.

METHODS

Skin chamber appended to sites of allergen and diluent control challenge with hourly collections. Then, study of exuding leucocytes in chamber bases.

RESULTS

In the allergen-challenged sites, histamine release peaked in the first hour, then low level release over the next 5 h. Lactoferrin release from neutrophils started by the second hour, likely associated with released IL-8. Eosinophil cationic protein levels started increasing slightly later. The percentage of exuding leucocytes which were activated was significantly higher in the allergen challenge sites than in the control challenge sites

CONCLUSIONS

Both gross LPR and local inflammatory cell responses in the skin start soon after the immediate mast cell activation in IgE-mediated responses. Such inflammatory responses include leucocyte activation and mediator release.

Allergen-induced cytokine secretion in relation to atopic symptoms and immunoglobulin E and immunoglobulin G subclass antibody responses

There are few studies on allergen-induced cytokine production in allergic children, and little is known of antigen-specific cytokine regulation of human immunoglobulin (Ig) G subclass antibody responses. An association with T-helper 1 (Th1)-like immunity and complement-activating antibodies remains to be demonstrated in humans. We have previously observed that atopic symptoms are associated with high levels of IgG subclass, especially IgG4, antibodies to birch and beta-lactoglobulin. The differences were seen early in life for the food allergen and increased with age for the inhaled allergen. The aim of this study was to investigate the association between atopic symptoms, birch allergen-, and beta-lactoglobulin-induced cytokine production in peripheral blood mononuclear cells (PBMC), and serum IgE and IgG subclass antibody responses to these allergens in children in order to further clarify the role of Th1- and Th2-like immunity in responses to various antigens. PBMC from 55 eight-year old children, who had been followed prospectively from birth, were stimulated with birch- and beta-lactoglobulin. Production of interleukin (IL)-5, IL-6, IL-10, IL-13 and interferon (IFN)-gamma was analysed by ELISA and expression of IL-4 and IL-9 mRNA by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). IgG subclass antibody levels to birch- and beta-lactoglobulin in serum were determined by ELISA, and IgE antibodies by Magic-Lite and CAP-RAST, respectively. Birch-induced expression of IL-4, but not of the other cytokines, was associated with IgE antibodies to birch. Furthermore, the IL-4 expression and IL-6 production correlated with serum IgG4 antibody levels to this allergen, and IFN-gamma secretion with IgG1 antibody responses. There were no correlations between beta-lactoglobulin-stimulated cytokine production and IgG subclass antibody levels to that allergen, except for a negative association between beta-lactoglobulin-stimulated IL-4 expression and IgG1 antibodies. Atopic children tended to have high levels of birch and beta-lactoglobulin-induced IL-5, IL-6 and IL-10 secretion. Birch-induced IL-4 expression may be the major factor in determining IgE antibody formation to that allergen, while allergen-induced IL-5, IL-6 and IL-10 secretion in PBMC is associated with atopic symptoms. Th1-like immunity to inhaled allergens could be associated with production of the opsonizing and complement-activating IgG1 antibody subclass, and Th2-like immunity with IgG4 antibody responses.

Toward a canine model of atopic dermatitis: amplification of cytokine-gene transcripts in the skin of atopic dogs

The objectives of the present study were to characterize and compare the repertoire of cytokine-genes transcribed in skin homogenates obtained from normal dogs and dogs with atopic dermatitis (AD) using a reverse-transcriptase polymerase chain reaction and canine-specific cytokine-gene primers. Whereas IL-4 and IL-5 cytokine-gene transcripts were detected more commonly in atopic skin biopsy homogenates, IL-2 mRNA was amplified more often from normal control specimens. IFN-gamma mRNA was detected in 5/29 atopic specimens, 4 of them obtained from the only dog with chronic skin lesions. One-fourth of atopic samples exhibited clear type-2 cytokine profiles; the remainder did not demonstrate polarized repertoires. Conversely, type-1 cytokine profiles were characterized in one-fourth of normal control specimens. The present study establishes, for the first time, the transcription of type-2 cytokine-genes in the skin of dogs with AD. Future experiments investigating the cellular origin and dynamics of allergic cytokine-gene transcription are needed to confirm whether or not canine AD could be considered an immunological model for a human disease.

Chemical mediators in atopic dermatitis: involvement of leukotriene B4 released by a type I allergic reaction in the pathogenesis of atopic dermatitis

BACKGROUND

The mediators produced from a type I allergic reaction have not yet been able to explain the pathogenesis of atopic dermatitis (AD).

OBJECTIVE

The purpose of this study was to elucidate the involvement of leukotriene (LT) B4 produced from a type I allergic reaction in the pathogenesis of AD.

METHOD

The release of LTB4 was measured both in vitro, in passively sensitized and antigen-challenged human skin slices, as well as in vivo, in skin chambers on patients with AD.

RESULTS

LTB4 was released from in vitro human skin by stimulation of the antigen (54.9 +/- 14.6 pg/g wet weight of skin by antigen challenge and 28.0 +/- 11.1 pg/g in control skin, P <.002). Antigen-specific release of LTB4 and histamine was also observed in vivo in nonlesional skin from the patients with AD by using the skin chamber technique.

CONCLUSION

LTB4 release during type I allergic reaction in human skin has been determined in vitro. The released LTB4 possibly contributes to cellular response at the acute inflammatory lesion of AD.

Comparison of inflammatory events during developing immunoglobulin E-mediated late-phase reactions and delayed-hypersensitivity reactions

To compare cellular and mediator responses in early developing late-phase skin reactions (LPR) and delayed-hypersensitivity (DH) reactions in the same subjects, responses in skin chambers overlying sites of challenge with pollen antigen and Candida albicans antigens were compared in six humans with demonstrated prominent LPR and DH responses. Histamine levels in overlying chamber fluids at 1 h were much higher at LPR than at DH sites (P = 0.002). After the next 4 h, leukocyte exudation was higher at LPR than at DH sites (P = 0.005). Most leukocytes were activated neutrophils with greater frequency of superoxide-secreting cells and released lactoferrin at LPR than at DH sites (P = 0.01 and P = 0.02, respectively). The frequency of exuding eosinophils was higher, but not significantly so (P = 0.5), at LPR sites. Although significantly more eosinophils at LPR sites were activated (P = 0.02), the levels of released eosinophilic cationic protein were not significantly higher at LPR sites (P = 0.09). The levels of interleukin-8 (IL-8), but not IL-6, were greater at LPR than at DH sites. During the first 5 h of challenge there was greater mast cell activation and subsequent exudation of activated neutrophils at sites of developing LPR than at DH sites, possibly related to greater local IL-8 levels. The frequency of activated eosinophils was also greater at LPR sites. These different initial inflammatory responses could play a role in determining expression of LPR or DH reactions.

Increased interleukin-6 production during the acute phase of the syndrome of episodic angioedema and hypereosinophilia

BACKGROUND

The Gleich syndrome is rare and associates recurrent angioedema, urticaria, fever, weight gain and blood hypereosinophilia, underlying systemic and local inflammation. The pathogenesis of those symptoms remains unclear.

OBJECTIVE

We wanted to address the possible implication of Interleukin-6 (IL-6) in the development of those clinical features, and to identify the cells involved in its production.

METHODS

A 26-year-old man suffering of this disease was referred in hospital. During an acute attack with weight gain, fever and a diffuse oedema, a marked increase in eosinophils count (42700/mm3 was observed. Serum ECP was elevated at 47 microg/L (normal less than 16). Corticosteroid therapy administrated on the 7th day was followed by a rapid remission. Blood samples were collected (before, during the attack and under corticosteroid therapy) for measurements of serum IL-6 (ELISA, Immunotech, Marseille, France) and plasma histamine (RIA, Immunotech, Marseille, France). Blood monocytes and eosinophils were isolated and a skin biopsy was performed during the attack.

RESULTS

The plasma histamine level was within normal range. The level of IL-6 in sera peaked to 74 pg/mL, concomitant with the peak of eosinophilia at the acute phase phase of the attack. Under corticosteroids, we observed a drop in the IL-6 serum level to 29 pg/mL, concomitant with the clinical remission. During the attack, an increase in IL-6 production was observed in 24 h blood monocyte supernatants (11.10(3) pg/mL compared with 2.4+/-0.8.10(3) pg/mL for BM from controls) as well as in skin endothelial cells but not in the blood and skin eosinophils. In vitro, when endothelial cells were incubated in eosinophils supernatants of the patient, liberation of IL-6 was observed (3.3 10(3) pg/mL compared with controls: 2.1 10(3) pg/mL) CONCLUSION: Serum IL-6 elevation may be related to an increased production by blood monocytes and endothelial cells, possibly stimulated by eosinophil mediator during the acute phase of the disease, and might participate in the inflammatory reaction of this syndrome.

Comparison of inflammatory events in skin sites with and without cutaneous late-phase reactions after prominent immediate IgE-mediated responses

BACKGROUND

A number of inflammatory events have been detected in skin chambers overlying sites of developing late-phase reactions (LPR) to pollen antigens in sensitive subjects. However, the pathogenic significance of such events is still unclear.

OBJECTIVE

We sought to compare inflammatory responses and cytokine levels in skin chambers that overlie sites of antigen challenge in individuals with and individuals without LPRs after immediate wheal responses of similar intensity.

RESULTS

Early histamine releases at antigen sites were similar in eight subjects with LPR (+/+ group) and eight subjects without LPR (+/- group). However, histamine releases during hours 2 through 5 of antigen challenge were significantly greater in the +/+ subjects than in the +/- subjects. Total exuding leukocytes; percent eosinophils; and levels of eosinophil cationic protein, lactoferrin, and IL-8 were significantly greater at antigen versus buffer control challenge sites in both the +/+ and +/- groups, with no significant differences between the groups. IL-1 and IL-6 levels were not greater at antigen sites than at buffer sites.

CONCLUSIONS

The only significantly greater antigen-induced response detected in +/+ subjects than in +/- subjects was in later histamine release, which is possibly a marker of other inflammatory responses because histamine itself does not induce LPRs. Other inflammatory events assessed may be somewhat greater in +/+ subjects, but not significantly so.

Cytokine levels and inflammatory responses in developing late-phase allergic reactions in the skin

BACKGROUND

Cytokines could play roles in the attraction of leukocytes into sites of IgE-mediated late-phase reactions (LPR) or in the activation of such cells at the sites. Previous studies found increased release of IL-6, IL-1, and granulocyte-macrophage colony-stimulating factor into skin chambers overlying allergen-challenged sites, mainly after 6 hours when LPR are already well-developed.

OBJECTIVE

To compare levels of several cytokines with inflammatory responses in skin chambers overlying developing LPRs.

METHODS

Skin chambers were appended to denuded blister bases in 15 sensitive subjects, then challenged over a 5-hour period with pollen allergens (Ag) or buffer control (B). Levels of several chemotactic cytokines, eosinophil cationic product (released from eosinophils), and lactoferrin (released from neutrophils) were measured and leukocyte accumulation was assessed.

RESULTS

Levels of the chemokines IL-8, RANTES, and monocyte chemotactic protein-1 (but not IL-1, IL-6, or granulocyte-macrophage colony-stimulating factor) were significantly higher at Ag-challenge sites than at B-challenge sites. IL-5 was not detected. In individual chamber fluids at Ag-challenge sites, (1) IL-8 levels correlated strongly with levels of lactoferrin but not with eosinophil cationic protein levels; (2) RANTES levels correlated with numbers of eosinophils but not with eosinophil cationic protein levels; and (3) levels of monocyte chemotactic protein-1 correlated weakly with histamine released after the first hour.

CONCLUSIONS

During LPRs developing during the first 5 hours of Ag challenge, there is increased local release of several chemokines, which could play roles in the observed attraction and subsequent activation of leukocytes and continued histamine release observed at such sites.

Histamine selectively enhances human immunoglobulin E (IgE) and IgG4 production induced by anti-CD58 monoclonal antibody

We studied the effects of histamine on human immunoglobulin (IgE) and IgG4 production. Histamine selectively enhanced IgE and IgG4 production in purified surface IgE and IgG4 negative (sIgE-sIgG4-) B cells from normal donors stimulated with interleukin (IL)-4 plus anti-CD58 or IL-13 plus anti-CD58 monoclonal antibody (mAb) without affecting production of IgG1, IgG2, IgG3, IgM, IgA1, or IgA2. In cultures with IL-4 plus anti-CD58 mAb, histamine-induced enhancement of IgE and IgG4 production was specifically blocked by thioperamide (H3 receptor antagonist), and was inhibited by anti-IL-10 antibody (Ab). In contrast, in cultures with IL-13 plus anti-CD58 mAb, histamine-induced enhancement was blocked by dimaprit (H1 receptor antagonist), and was inhibited by anti-IL-6 mAb. Histamine also enhanced IgE and IgG4 production by in vivo-generated sIgE+ and sIgG4+ B cells, respectively, from atopic patients; enhancement was blocked by dimaprit and thioperamide, and was inhibited by anti-IL-6 mAb and anti-IL-10 Ab. In sIgE-sIgG4- B cells, IL-4 plus anti-CD58 mAb induced IL-10 production and IL-10 receptor expression, whereas IL-13 plus anti-CD58 mAb induced IL-6 production and IL-6 receptor expression. Histamine increased IL-10 and IL-6 production without affecting IL-10 and IL-6 receptor expression, in cultures with IL-4 plus anti-CD58 mAb and with IL-13 plus anti-CD58 mAb, respectively, which was blocked by thioperamide and dimaprit, respectively. In contrast, sIgE+ and sIgG4+ B cells spontaneously produced both IL-6 and IL-10 and constitutively expressed IL-6 and IL-10 receptors, and histamine increased IL-6 and IL-10 production without affecting IL-6 or IL-10 receptor expression, which was blocked by thioperamide and dimaprit. These results indicate that histamine enhanced IgE and IgG4 production by increasing endogenous IL-6 and IL-10 production via H1 and H3 receptors, respectively.

Prominent neutrophilic inflammation in sputum from subjects with asthma exacerbation

To infer possible mechanisms of acute airway inflammation and mucus hypersecretion in acute severe asthma, we performed cellular and biochemical analysis on sputum from 18 adults with acute severe asthma and compared the results with results of analysis of sputum from 12 adults with cystic fibrosis (CF). We found that in subjects with asthma neutrophils made up more than 75% of sputum cells in 10 samples whereas eosinophils made up more than 75% of cells in only three samples. Fifty percent of the subjects with asthma reported that their asthma exacerbation was precipitated by a respiratory tract infection, and these subjects had a significantly higher percentage of neutrophils in their sputum (85% +/- 6% vs 57% +/- 12%, p = 0.05). In the CF samples neutrophils made up more than 95% and eosinophils less than 1% of cells in all samples analyzed. Analysis of fluid phase chemicals in asthmatic and CF sputum samples showed that despite overall lower mean values of neutrophil elastase (27 +/- 11 micrograms/ml vs 466 +/- 121 micrograms/ml, p = 0.0001) and interleukin-8 (IL-8) (55 +/- 15 ng/ml vs 186 +/- 24 ng/ml, p = 0.0001), some of the asthmatic samples had values for these variables that overlapped those in the CF samples. In addition, the asthmatic samples were distinguished by the presence of higher tryptase (10 +/- 7 U/L vs 0.9 +/- 0.9 U/L, p = 0.0001) and interleukin-6 (1166 +/- 447 ng/ml vs 186 +/- 24 ng/ml; p = 0.0001) levels and by a higher ratio of albumin to mucin-like glycoprotein (0.8 +/- 0.5 vs 0.1 +/- 0.002, p = 0.02). DNA levels were lower in the asthmatic samples (0.5 +/- 0.3 mg/ml vs 3.5 +/- 1.2 mg/ml, p = 0.05). We conclude that neutrophils predominate more frequently than eosinophils as the major inflammatory cell in sputum from patients with asthma in acute exacerbation. We speculate that this may be because respiratory tract infections are a frequent precipitant of acute asthma. In addition, the high IL-8 levels and free neutrophil elastase activity observed in asthmatic sputum suggests that IL-8 may mediate airway neutrophilia in acute asthma and that neutrophil elastase may mediate mucin glycoprotein hypersecretion in acute asthma, as has been proposed for the mucin hypersecretion in CF.

Histamine induces IL-6 production by human endothelial cells

Histamine is one of the major mediators implicated in the physiopathology of allergy. On vascular endothelium, histamine mainly induces early effects: an increase in vasopermeability leading to oedema, a release of lipid mediators and a transient expression of P-selectin. The aim of this study was to evaluate the effects of histamine on adhesion molecule expression and IL-6 production by human endothelial cells. Histamine did not modulate the expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin, but induced a transient expression of P-selectin as previously reported. In addition, histamine increased in a dose- (from 10(-5) to 10(-3) M) and time- (from 4 h to 24 h) dependent fashion the IL-6 synthesis by endothelial cells. Tumour necrosis factor-alpha (TNF-alpha)-induced IL-6 production was also potentiated in a dose-dependent manner by histamine, without modification of the time course of IL-6 secretion. Moreover, this increase of IL-6 production induced by histamine was inhibited in a dose-dependent manner by H1 and H2 histamine receptor antagonists (50% inhibition of IL-6 production at 5 x 10(-4) M and 4 x 10(-5) M, respectively). So, histamine induces, besides already well known effects, a late stimulation of endothelial cells, i.e. the production of IL-6.

An inflammatory eruption associated with recombinant human IL-6

Interleukin 6 (IL-6) is an endogenous cytokine with multiple biological functions, including amplification of the inflammatory response. Recombinant human IL-6, administered as part of a chemotherapeutic regimen, has recently been shown to cause regression of certain types of malignant tumours. We report a patient who developed a cutaneous eruption consisting of coalescent, erythematous, scaling macules and papules after administration of recombinant human IL-6, given as part of her chemotherapy for ductal carcinoma of the breast.

The effect of immunotherapy on the cutaneous late phase response to antigen

BACKGROUND

This study used the skin chamber model to evaluate prospectively the effect of immunotherapy (IT) on the cutaneous early and late phase response (LPR) to epicutaneous antigen challenge.

METHODS

Nine subjects with allergic rhinitis were studied at three time points: before starting IT, after 3 months of IT, and after 6 months of IT. Skin chamber histamine content was measured hourly for 12 hours, and cell counts performed hourly during hours 6 to 12. An intradermal skin test was placed, and the reaction was measured hourly for 12 hours. Skin biopsy specimens were obtained 8 hours after intradermal placement and evaluated for cellular infiltrate and major basic protein deposition. Serum antigen-specific IgG and IgE levels were measured at each time point to confirm physiologic effect of IT.

RESULTS

Six months of IT significantly (p < 0.05) decreased both early and LPR skin test reactivity and skin chamber histamine for hours 1 to 3, 4 to 6, and 9 to 12. Skin chamber LPR cellular influx decreased significantly (p < 0.05) for neutrophils only. Decrease in LPR histamine after 6 months of IT was significantly correlated with both decrease in mononuclear cells (R2 = 0.817, p = 0.002) and decrease in neutrophils (R2 = 0.813, p = 0.009). Also significantly correlated were decrease in LPR skin test reactivity, with percent change in skin chamber mononuclear cells (R2 = 0.800, p = 0.009) and decrease in early skin test reactivity (R2 = 0.675, p = 0.01). Biopsy specimens showed no consistent change in either dermal cellular infiltrate or deposition of major basic protein.

CONCLUSION

IT significantly attenuates cutaneous histamine release and skin test reactivity and is accompanied by a decrease in skin chamber LPR neutrophil influx without significantly altering the dermal infiltrate at 8 hours.

The late-phase reaction: role of IgE, its receptor and cytokines

Late phase IgE-mediated reactions (LPR) likely play a major role in the pathogenesis of chronic allergic diseases. Although a number of cellular and humoral alterations in LPR sites have been described recently, the pathogenesis of the LPR is still unclear. LPR follow IgE-mediated but not opiate-induced mast-cell activation suggesting different patterns of mast cell mediator release and/or additional effects of the antigen-IgE interaction. Granulocyte accumulation in developing LPR is accompanied by altered expression of adhesion molecules on local vascular endothelium. Lymphocytes and the cytokines they produce play an important role in developing and perpetuating LPR. These findings point to the likely complex pathogenesis of LPR with implications for the therapy of allergic diseases.

Recombinant interleukin-1 receptor antagonist protein prevents sensitization and intestinal anaphylaxis in guinea pigs

Recombinant interleukin-1 receptor antagonist protein (rlRAP, 0.5 mg/kg) administered intraperitoneally in guinea pigs one hour before primary and booster parenteral sensitization (1 ml) by cow milk, led to a reduced immunoglobulin E (IgE) production, as displayed by a passive cutaneous anaphylaxis test. rlRAP administered intraperitoneally in sensitized guinea pigs at 0.5 mg/kg 10 min before challenge administration (beta-lactoglobulin, 100 mg per os), also prevents the colonic motor and secretory changes induced by intestinal anaphylaxis. These results suggest the involvement of interleukin-1 in food allergy and evidence a double protective role for rlRAP in food hypersensitivity.