A potent immunosuppressant FK506 inhibits IL-8 expression in human eosinophils

Tacrolimus successfully used to control refractory eosinophilic granulomatosis with polyangiitis complicated by invasive aspergillosis and chronic hepatitis B

While several alternatives to cyclophosphamide have been proposed for refractory eosinophilic granulomatosis with polyangiitis (EGPA), therapeutic options are limited in patients with chronic infections. We report a case of refractory EGPA complicated by invasive aspergillosis and chronic hepatitis B. Although multiple immunosuppressants, including cyclophosphamide, were not effective, tacrolimus was used successfully to control disease without exacerbating concomitant infections in the long term. Tacrolimus could be an alternative choice in the treatment of EGPA, especially when aggressive immunosuppression is unfeasible.

Eosinophilia, regardless of degree, is related to better outcomes after allogeneic hematopoietic stem cell transplantation

OBJECTIVE

Several recent studies report that, after allogeneic hematopoietic cell transplantation (allo-HCT), eosinophilia is a favorable factor for transplant outcomes. However, whether the degree of eosinophilia influences transplant outcomes is yet to be established.

METHODS

We studied 144 patients with hematological malignancy who received allo-HCT at our institution. The stem cell sources were bone marrow in 84 patients, peripheral blood stem cells in 32 patients, and cord blood in 28 patients. One hundred and twelve patients underwent myeloablative conditioning and 49 patients had high-risk disease. We performed semi-landmark analysis to examine the influence of eosinophilia.

RESULTS

Eosinophilia developed at a median of 47 days after transplantation in 63 patients (44%). The patients with eosinophilia showed significantly better overall survival (OS) and a lower relapse rate at three years, compared to those without eosinophilia (66% vs 55%, p=0.04 and 30% vs 50%, p=0.002). On analysis following division into groups with mild (500-1,500×10(6)/L) and hyper- (>1,500×10(6)/L) eosinophilia, three-year OS and relapse rates were 68% and 65% (p=0.92), and 31% and 28% (p=0.90), respectively. On multivariate analysis, eosinophilia was significantly associated with lower relapse rates [HR: 0.5 (95% CI: 0.3-0.9), p=0.01] and the same trend was preserved in the analysis of the mild and hyper-eosinophilic groups.

CONCLUSION

The results suggest that eosinophilia after allo-HCT was associated with better OS and a lower relapse rate, regardless of the levels. The mechanism of this effect is still unclear, and requires study of the pathophysiological process to clarify the relationship between the higher levels of eosinophilia after allo-HCT and organ infiltration.

The impact of tacrolimus on vascular endothelial growth factor in experimental corneal neovascularization

PURPOSE

To investigate the impact of tacrolimus on vascular endothelial growth factor (VEGF) in experimental corneal neovascularization (NV) immunohistochemically.

MATERIAL AND METHODS

Five groups of seven Wistar albino rats were formed. A silver nitrate cauterization technique was used to induce corneal NV in the study groups, excluding Group 1 (Control Group). Rats in group 1 did not receive any treatment. Rats in group 2 (sham 1) were administered 1 ml of saline intraperitoneally once a day and those in group 3 (sham 2) received one drop of saline four times a day. Rats in group 4 were administered 0.3 mg/kg tacrolimus intraperitoneally once a day. For group 5, 0.3 mg/ml tacrolimus was installed four times a day. Digital photography for each cornea was performed and the percentage area of the NV on the total corneal surface was calculated. The intensity of VEGF immunostaining in the epithelial, the stromal, and endothelial layers was performed in a semi quantitative fashion.

RESULTS

The mean percentages of the neovascularized areas of intraperitoneally and topically tacrolimus-treated groups were lesser than those of the sham groups (p = 0.002, p = 0.038, respectively). The mean intensity of the epithelial VEGF immunostaining of the intraperitoneally tacrolimus-treated group was less than that of its sham group (p = 0.002), while the mean intensity of the stromal VEGF staining of the topically tacrolimus-treated group was lesser than that of its sham group (p = 0.042). The intensities of the endothelial VEGF immunostaining of the intraperitoneally and topically tacrolimus-treated groups were less than those of the sham groups (p = 0.038, p = 0.032).

CONCLUSION

Systemic and topical administration of tacrolimus may be beneficial in the prevention of corneal NV because of its effect on VEGF.

Pimecrolimus reduces eosinophil activation associated with calcium mobilization

BACKGROUND

Pimecrolimus is a calcineurin inhibitor that inhibits T cell and mast cell activation and effectively treats atopic dermatitis. However, its effects on eosinophils, a cell type implicated in allergic disease pathology, are unknown. Therefore, we examined the effects of pimecrolimus on eosinophil superoxide anion production, degranulation and survival.

METHODS

Purified eosinophils from normal or atopic donors were incubated with serial dilutions of pimecrolimus (microM to nM) and then stimulated with platelet activating factor (PAF), interleukin 5 (IL5), secretory immunoglobulin A (sIgA) or Alternaria alternata (Alt) fungus extract. Eosinophil activation was monitored by cytochrome c reduction resulting from superoxide anion production and by a 2-site immunoassay for eosinophil-derived neurotoxin (EDN) in cellular supernatants, as a marker of degranulation. Eosinophil survival was measured by propidium iodide exclusion using flow cytometry after 4 days in culture.

RESULTS

Normal and atopic eosinophil superoxide anion production induced by PAF, and associated with increased intracellular calcium, was inhibited up to 37% with 1 microM pimecrolimus. However, superoxide anion production induced by IL5 and sIgA was not consistently inhibited. EDN release, which ultimately depends on calcium, was inhibited about 30% with PAF, IL5 and sIgA stimulation for normal and atopic donor eosinophils. Furthermore, calcium-dependent Alt-induced EDN release was inhibited up to 49% with nanomolar pimecrolimus. Finally, increased eosinophil survival promoted by IL5 and sIgA was not influenced by pimecrolimus.

CONCLUSION

Pimecrolimus moderately inhibits eosinophil superoxide anion production and EDN release associated with calcium mobilization, which may contribute to its efficacy in treating atopic dermatitis.

The safety of tacrolimus ointment for the treatment of atopic dermatitis: a review

Tacrolimus ointment is a topical calcineurin inhibitor (TCI) that was developed specifically for the treatment of atopic dermatitis (AD). It is one of the most extensively tested dermatological products, with more than 19 000 patients (including approximately 7600 children) having participated in the tacrolimus ointment clinical development programme. Recent regulatory reviews have focused on the potential risk of malignancy with TCIs, based on their mode of action and the effects of systemic tacrolimus when given to transplant recipients. Studies have shown, however, that the systemic absorption of tacrolimus when applied topically is very low, with blood concentrations being below the level of quantification in most patients. Moreover, TCIs are not associated with a decrease in immunocompetence in the skin and there is no increase in the incidence of infections with long-term treatment. More than 5.4 million prescriptions for tacrolimus ointment have been issued worldwide, with no evidence of an increased risk of malignancy in adults or children compared with the general population. Similarly, epidemiological studies have failed to demonstrate an increased incidence of skin cancer in patients using TCIs. The most common adverse events (AEs) that occur with tacrolimus ointment treatment are transient application-site reactions, such as burning or pruritus. These complications are related to disease severity, and decrease in frequency over time as AD improves. The incidence of nonapplication-site AEs does not increase with long-term treatment, and most such events occurring in clinical trials were considered to be unrelated to therapy. Although it is important that clinicians are aware of the recent changes in product labelling, extensive clinical trials continue to show that tacrolimus ointment is well tolerated, and is generally an effective therapy for suitable patients with AD.

Selective suppression of dendritic cell functions by Mycobacterium ulcerans toxin mycolactone

Mycolactone is a polyketide toxin produced by Mycobacterium ulcerans (Mu), the causative agent of the skin disease Buruli ulcer (BU). Surprisingly, infected tissues lack inflammatory infiltrates. Structural similarities between mycolactone and immunosuppressive agents led us to investigate the immunomodulatory properties of mycolactone on dendritic cells (DCs), the key initiators and regulators of immune responses. At noncytotoxic concentrations, phenotypic and functional maturation of both mouse and human DCs was inhibited by mycolactone. Notably, mycolactone blocked the emigration of mouse-skin DCs to draining lymph nodes, as well as their maturation in vivo. In human peripheral blood–derived DCs, mycolactone inhibited the ability to activate allogeneic T cell priming and to produce inflammatory molecules. Interestingly, production of the cytokines interleukin (IL) 12, tumor necrosis factor α, and IL-6 was only marginally affected, whereas production of the chemokines macrophage inflammatory protein (MIP) 1α, MIP-1β, regulated on activation, normal T cell expressed and secreted, interferon γ–inducible protein 10, and monocyte chemoattractant protein 1 was abolished at nanomolar concentrations. Importantly, mycolactone endogenously expressed by Mu mediated similar inhibitory effects on β-chemokine production by DCs. In accordance with the histopathological features of BUs, our results suggest that bacterial production of mycolactone may limit both the initiation of primary immune responses and the recruitment of inflammatory cells to the infection site. Moreover, they highlight a potential interest in mycolactone as a novel immunosuppressive agent.

Eosinophilic folliculitis in a Caucasian patient: association with toxocariasis?

Sterile eosinophilic folliculitis, a clinical entity first described by Ofuji in 1970, is a rather rare skin disorder, in particular in the non-Asian population. We report the first case of eosinophilic folliculitis associated with toxocariasis in a Caucasian patient. Topical and systemic anti-inflammatory and antiphlogistic therapy along with systemic antihelminthic treatment resulted in complete remission of the skin lesions. In addition, there was a marked decrease of antibodies to Toxocara antigens in the patient's serum following antihelminthic therapy. Given that (I) some cases of eosinophilic folliculitis have been reported which were associated with infestation with metazoan parasites; (2) infestations with the roundworm Toxocara canis are known to induce eosinophilic reactions in some tissues; and (3) therapy-induced remission of eosinophilic folliculitis was accompanied by a decrease of Toxocara-directed antibodies in the patient's serum, we propose that there is an aetiopathogenic link between toxocariasis and eosinophilic folliculitis in this patient.

The role of topical calcineurin inhibitors in atopic dermatitis:

For more than five decades, topical corticosteroids and emollients have been the mainstay of therapy for atopic dermatitis. However, the potential for side-effects limits the clinical utility of corticosteroids in providing long-term disease control. With a unique mode of action that differs from that of corticosteroids, the steroid-free topical calcineurin inhibitors (TCIs), tacrolimus ointment and pimecrolimus cream, provide skin-selective treatment that targets key factors involved in the pathogenesis of this chronic disease. An extensive series of clinical trials involving more than 16,000 patients with predominantly moderate to severe atopic dermatitis in tacrolimus studies and over 2000 patients with primarily mild to moderate disease in pimecrolimus studies has shown that both TCIs provide effective and well-tolerated treatment for atopic dermatitis. Randomized controlled trials have demonstrated that tacrolimus is superior to conventional hydrocortisone-based regimens and does not cause skin atrophy or other steroidal side-effects. Both tacrolimus and pimecrolimus prevent disease flares and provide progressive and sustained disease improvement with long-term therapy. These and other clinical benefits of TCIs are discussed, together with the safety profiles of tacrolimus and pimecrolimus and their use in clinical practice. In addition, this review summarizes findings from the many trials carried out with these agents and outlines how TCIs can provide long-term treatment and control of a chronic skin disease that may persist for years.

Investigation on the effects of topical therapy with 0.1% tacrolimus ointment (ProtopicR) on intradermal skin test reactivity in atopic dogs

Tacrolimus ointment (TAC) is an effective treatment for atopic dermatitis in humans and dogs. The purposes of the present study were to evaluate the effect of 4 weeks of TAC on intradermal skin testing (IST), and in case of suppression, to investigate if reactivity returned to baseline by 2 or 4 weeks post treatment. Intradermal skin test was performed using saline, histamine, lipopolysaccharide (LPS, 0.4 mg mL(-1)), house dust (25 PNU mL(-1)) and house dust mite (1 : 40 000 w/v) at weeks 0, 4, 6 and 8 on nine dogs enrolled in a blinded, crossover, clinical trial, using 0.1% TAC or placebo once daily for 4 weeks. Reactions were evaluated at 15 min, and at 4 and 6 h. Ointment was applied after the 15-min evaluation on weeks 0 and 4. Data were analysed using the statistical software SAS System for Windows. At week 4, TAC did not affect 15-min IST, but some reactions in the TAC group were suppressed at 6 h compared to baseline. In the TAC group, 4-h IST reactivity was reduced 2 weeks after discontinuation but returned to baseline by 4 weeks. In conclusion, TAC has no effect on immediate reactions but decreased some late-phase reactions. Therefore, no withdrawal is recommended to evaluate only immediate reactions, but a 4-week withdrawal may be necessary for evaluation of late-phase reactions.

Topical application of the immunosuppressant tacrolimus accelerates carcinogenesis in mouse skin

BACKGROUND

Tacrolimus, produced by the fungus Streptomyces tsukabaensis, is a potent macrolide immunosuppressant widely used in liver and kidney transplantation. Topical tacrolimus has recently been found to be an effective treatment for atopic dermatitis (AD).

OBJECTIVES

Because of the well-known association between T-cell immunosuppression and an increased risk of carcinogenesis, we investigated the effect of topical tacrolimus on skin carcinogenesis in 117 mice.

METHODS

Approximately 8 cm2 of the shaved dorsal skin of 7-week-old female CD-1 mice was treated with 7,12-dimethylbenz[alpha]anthracene (DMBA) dissolved in acetone, which is in general use as a tumour initiator, or acetone alone, on day 1 of the experiment, followed by promoting treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) with or without tacrolimus, or acetone with or without tacrolimus, for 20 weeks. The mice were divided into six treatment groups: (1) DMBA followed by acetone; (2) DMBA followed by TPA; (3) DMBA followed by acetone + tacrolimus; (4) DMBA followed by TPA + tacrolimus; (5) acetone followed by acetone + tacrolimus; and (6) acetone followed by acetone (control).

RESULTS

The induction of skin tumours was significantly greater in the TPA-treated groups than in the absence of TPA. However, after 14 weeks there was marked synergy between tacrolimus and the DMBA/TPA regimen, with 0.47 +/- 0.13 (mean +/- SD) new tumours per mouse per week in group 4 vs. 0.10 +/- 0.025 in group 2 (P < 0.01), and 0.01 +/- 0.002 in group 3. A significant reduction in the CD4/CD8 ratio was found in axillary and inguinal lymph nodes in tacrolimus-treated mice, supporting the presumption that the immunosuppressive effect of the drug was responsible for its effect in promoting tumorigenesis. The major increase in tumours caused by topical tacrolimus was of papillomas, not squamous cell carcinomas. Papillomas are uncommon in humans, and are benign. However, 8.5% of the tumours found in the experiment were squamous cell carcinomas, and a considerable synergy between topical tacrolimus and conventional carcinogens was observed, raising the spectre of some risk of skin carcinogenesis in AD patients undergoing prolonged treatment with tacrolimus.

CONCLUSIONS

Caution and careful surveillance are required with regard to skin lesions in patients treated with tacrolimus for prolonged periods.

Production and pharmacologic modulation of the granulocyte-associated allergic responses to ovalbumin in murine skin models induced by injecting ovalbumin-specific Th1 or Th2 cells

Because interferon-gamma, interleukin-4, and interleukin-5 have been identified at the mRNA and protein levels in the lesional skin of patients with atopic dermatitis, we investigated the roles played by granulocytes as effector cells in allergic inflammation by using two unique murine skin models. In vitro generated Th1 and Th2 cells from naïve splenocytes of antiovalbumin T cell receptor transgenic BALB/C mice were adoptively transferred with ovalbumin into the ear pinnae or air-pouches produced in the back skin of naïve, nontransgenic BALB/C mice. The injection of Th1 cells with ovalbumin induced delayed type ear swelling that peaked at 48 h, whereas that of Th2 resulted in ear swelling that peaked at a much earlier time, 24 h. Histologic study of the swollen ear skin and granulocytes recruited into the air-pouch demonstrated that, although the Th1-induced inflammation caused a neutrophil-predominant infiltrate with few eosinophils, larger numbers of eosinophils accumulated in the Th2-induced inflammation. Using these murine models, we further evaluated the effects of drugs used for the treatment of atopic diseases. The results showed that FK506 administration could effectively reduce skin inflammation induced by either Th cells. Interestingly, the neutrophil elastase inhibitor ONO-6818 efficiently inhibited Th1-induced inflammation. In contrast, a leukotriene receptor antagonist, ONO-1078, specifically suppressed Th2-induced inflammation. We also found that each ONO drug exerted direct influence on specified granulocytes, as neither affected in vitro production of relevant Th cytokines. Thus, we succeeded in developing animal skin inflammation models in which we can evaluate the contribution of protein antigen-specific Th1 or Th2 cells through the action of granulocytic effector cells.

Effects of dexamethasone and FK506 on Helicobacter pylori-induced gastritis and bacterial viability in Mongolian gerbils

FK506 and dexamethasone were used to investigate whether or not immunosuppression affects H. pylori colonization and gastric mucosal damage induced by Helicobacter pylori in Mongolian gerbils. Two weeks after H. pylori infection, FK506 and dexamethasone or vehicle alone were subcutaneously administered once daily for the following 2 weeks. FK506 or vehicle alone was administered subcutaneously once daily for 5 weeks (1 week before and 4 weeks after infection). In H. pylori-infected animals for 4 weeks, hemorrhagic erosions and inflammatory responses (neutrophil infiltration and lymphoid follicle formation) were induced in gastric mucosa at an incidence of 100%. Both FK506 and dexamethasone administered for 2 weeks markedly reduced such mucosal changes. In these animals, H. pylori viability in the stomach was significantly elevated. FK506 administered for 5 weeks also significantly inhibited the hemorrhagic erosions, edema and neutrophil infiltration in the stomach. H. pylori viability was slightly elevated as compared with the control. It was concluded that the host immune responses might play dual roles both by deteriorating gastritis induced by H. pylori and by protecting against H. pylori infection in its early stage.

FK506 suppresses neutrophil chemoattractant production by peripheral blood mononuclear cells

To understand the mechanism of action of FK506 (Tacrolimus) on neutrophil chemotaxis, we examined its effect on human neutrophil chemotaxis and neutrophil chemoattractant production by peripheral blood mononuclear cells. FK506 and cyclosporin A had no direct suppressive effect on neutrophil chemotaxis induced by interleukin-8, leukotriene B(4), complement 5a (C5a), zymosan-activated serum and formyl-Met-Leu-Phe (fMLP). FK506 and cyclosporin A only slightly suppressed the chemotactic activity of platelet-activating factor (PAF). Dexamethasone did not inhibit the chemotactic activity of any chemoattractant. The supernatant of peripheral blood mononuclear cells stimulated with anti-CD3 and CD2 antibodies induced neutrophil chemotaxis. FK506 and cyclosporin A suppressed the chemotactic activity of the supernatant in parallel to the suppression of interleukin-8 production by peripheral blood mononuclear cells. Anti-interleukin-8 antibody completely suppressed the chemotactic activity of the supernatant without drugs. These studies indicate that FK506 may exert a beneficial effect on human inflammatory diseases by suppressing neutrophil chemotaxis secondary to inhibition of chemoattractant (for example, interleukin-8) production by leukocytes.

Induction and secretion of the chemokines interleukin-8 and monocyte chemotactic protein-1 in human immature leukemia cell lines

We investigated expression and secretion of the chemokines interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) in human myeloid cell lines. Quantitative determination by ELISA revealed a significant constitutive production of both chemokines in the cell lines HL-60 and NB-4 (>1000 pg/ml IL-8 and >400 pg/ml MCP-1 per million cells), while in the cell lines EOL-1, KASUMI-1 and KG-1 only 10-100 pg/ml IL-8 and MCP-1 were detected. Tetradecanoyl phorbol acetate (TPA) strongly increased the IL-8 and MCP-1 amounts in the culture supernatants of all five cell lines. The TPA-induced NB-4 produced the largest amounts of both chemokines (>40,000 pg/ml). The strongest induction was seen in EOL-1 (>100-fold increase). Besides TPA, tumor necrosis factor-alpha (TNF alpha) also distinctively enhanced IL-8 and MCP-1 production. The calcium ionophore A-23187 and thapsigargin, an inhibitor of the Ca(2+)-ATPase, differentially induced IL-8 and MCP-1 secretion in the cell lines investigated, suggesting that, at least in some cell lines, intracellular free Ca(2+) might be important for chemokine secretion. Dexamethasone significantly prevented the IL-8 and MCP-1 production of stimulated cells, emphasizing the potent anti-inflammatory property of glucocorticoids. Similarly, the protein kinase inhibitor staurosporine clearly decreased the TPA-induced chemokine secretion in NB-4 cells, indicating the involvement of protein kinases in the signal transduction pathway which leads to enhanced chemokine secretion.