The effect of cyclosporin A, FK506 and rapamycin on the murine contact sensitivity reaction

Corneal Toxicity of Topical Tacrolimus Ointment in Mice with Corneal Epithelial Injury

Purpose: To investigate the effect of tacrolimus ointment on corneal epithelium. Methods: Eight-week-old male BALB/c mice were divided into 3 groups. In group 1, no injury was made. In group 2, the central 2-mm corneal epithelium was scraped off. In group 3, the whole corneal and limbal epithelium was removed after absolute ethanol application. In each group, the corneas were observed and treated daily with 0.03% or 0.1% tacrolimus ointment (Protopic^®). The viability of cultivated human corneal epithelial cells was also examined after 24-h incubation with various concentrations of tacrolimus. Results: Tacrolimus ointment significantly delayed the epithelial healing in corneas with epithelial injuries (groups 2 and 3) in dose- and frequency-dependent manners, whereas it did not have any effects on uninjured corneas (group 1). The proportion of terminal deoxynucleotidyl transferase-mediated nick end labeling-positive cells and mRNA levels of inflammatory cytokines were higher in tacrolimus-treated corneas, compared with controls. Tacrolimus did not directly reduce the viability of corneal epithelial cells in culture. Conclusions: Topical application of tacrolimus ointment onto the ocular surface induced toxicity in the cornea with epithelial defects through the impairment of epithelial healing and induction of apoptosis.

Reutilization of Tacrolimus Extracted from Expired Prograf® Capsules: Physical, Chemical, and Pharmacological Assessment

In this study, we investigated whether tacrolimus extracted and purified from the commercial capsules (Prograf® 5 mg) have retained its original quality and activity beyond the capsules expiration date in order to be reused for research purposes after extraction. High-performance liquid chromatography (HPLC) assay method was developed and validated for the quantification of tacrolimus, using cyclosporine A as an internal standard (IS). Moreover, a combination of analytical methods, including nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to assess the quality of extracted/purified tacrolimus. Suppression of murine peripheral-blood mononuclear cells (PBMC) proliferation and the levels of interleukin-2 (IL-2) and interferon gamma (IFN-γ) were also assessed. The data obtained showed no detectable differences in the quality profile between the authentic sample and extracted drug. Also, the results showed that the extracted/purified tacrolimus was able to suppress T cell proliferation, induced by concanavalin A, indicating the retained pharmacological activity. We proved that tacrolimus extracted/purified from expired Prograf® capsuled retains its purity and immunosuppressive activity and can be reused for research and possibly in pharmaceutical manufacturing.

Role of calcineurin in the regulation of human lung mast cell and basophil function by cyclosporine and FK506

BACKGROUND AND PURPOSE

Cyclosporine and FK506 are thought to act by targeting the Ca2+-dependent protein phosphatase, calcineurin. The aim of the present study was to determine whether cyclosporine and FK506 stabilize mast cells and basophils by interacting with calcineurin.

EXPERIMENTAL APPROACH

The effects of cyclosporine and FK506 on the IgE-mediated release of histamine from mast cells and basophils were evaluated. The presence of calcineurin in cells was determined by Western blotting. Ca2+-dependent protein phosphatase activities were assessed in cell extracts using a synthetic phosphorylated peptide that is known to serve as a substrate for calcineurin.

KEY RESULTS

FK506 was about 100-fold more potent than cyclosporine as an inhibitor of IgE-dependent histamine release from mast cells and basophils. Immunoblotting of solubilized preparations of purified cells demonstrated the presence of calcineurin in mast cells and basophils. In enzyme assays, mast cells expressed approximately 7-fold higher Ca2+-dependent protein phosphatase activity than basophils. Whereas cyclosporine effectively inhibited Ca2+-dependent protein phosphatase activity in cell extracts, FK506 was considerably less effective.

CONCLUSIONS AND IMPLICATIONS

FK506 and cyclosporine inhibit the stimulated release of histamine from mast cells and basophils. However, the ability of cyclosporine, but not FK506, to inhibit Ca2+-dependent protein phosphatase activity questions whether FK506 stabilizes mast cells and basophils by interacting with calcineurin.

Cilomilast, tacrolimus and rapamycin modulate dendritic cell function in the elicitation phase of allergic contact dermatitis

BACKGROUND

Cilomilast and tacrolimus as well as rapamycin are potential drugs for the treatment of allergic skin diseases like atopic dermatitis and allergic contact dermatitis.

OBJECTIVES

To compare the in vitro and in vivo immunomodulatory effects of the phosphodiesterase 4 inhibitor cilomilast with those of tacrolimus and rapamycin.

METHODS

The in vitro action of cilomilast, tacrolimus and rapamycin were tested in a mixed leucocyte reaction (MLR). In vivo, the inhibitory action of the immunomodulatory drugs was compared in the toluene-2,4-diisocyanate (TDI)-induced allergic inflammatory response with particular focus on dendritic cell (DC) function.

RESULTS

Cilomilast, tacrolimus and rapamycin were all able to inhibit DC-mediated T-cell activation in a MLR. But it was demonstrated for cilomilast that the target cells are T cells rather than DC. In vivo, a combination of systemic and topical administration of each of these three substances significantly inhibited swelling in the murine ear 16 h after TDI challenge. There was also a reduction in the weight of the draining auricular lymph node, in lymphocyte cell count, and in the number of emigrated DC. The density of Langerhans cells in the epidermis was correspondingly higher in mice treated with cilomilast, tacrolimus and rapamycin than in those treated with vehicle. All three substances were found to inhibit DC migration ex vivo in a skin DC migration assay performed on ear tissue after TDI challenge.

CONCLUSIONS

DC migration into the draining lymph node also takes place in the elicitation phase of allergic contact dermatitis and this migration can be influenced by tacrolimus and rapamycin, and, to a lesser extent, by cilomilast.

Suppression of nuclear translocation of nuclear factor-kappaB and nuclear factor of activated T cells by Younggaechulgam-tang

Younggaechulgam-tang (YGCGT) is known to suppress inflammatory and autoimmune responses, and it has clinically been used among Oriental medical doctors in South Korea. We investigated YGCGT-mediated changes in downstream T cell signal transduction. The expression levels of nuclear factor-kappaB (NFkappaB) subunit RelA and nuclear factor of activated T cells (NFATc1) in cytoplasm and nucleus were examined by western blot analysis. Interlukin-2 (IL-2) expression in MOLT-4 cells activated by phytohemagglutinin (PHA) was determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. IL-2 secretion was measured by an enzyme-linked immunosorbent assay (ELISA). PHA-induced translocation of Rel A and NFATcl to the nucleus were markedly reduced by YGCGT treatment. Furthermore, IL-2 mRNA and protein levels and IL-2 secretion were significantly diminished by YGCGT treatment. In conclusion, YGCGT treatment of T cells inhibits selectively nuclear translocation of RelA and NFATc1, resulting in diminished production of IL-2. These results suggest that YGCGT may have potential as immunosuppressive drugs with improved efficacy and reduced side effects.

The Pim kinases control rapamycin-resistant T cell survival and activation

Although Pim-1 or Pim-2 can contribute to lymphoid transformation when overexpressed, the physiologic role of these kinases in the immune response is uncertain. We now report that T cells from Pim-1(-/-)Pim-2(-/-) animals display an unexpected sensitivity to the immunosuppressant rapamycin. Cytokine-induced Pim-1 and Pim-2 promote the rapamycin-resistant survival of lymphocytes. The endogenous function of the Pim kinases was not restricted to the regulation of cell survival. Like the rapamycin target TOR, the Pim kinases also contribute to the regulation of lymphocyte growth and proliferation. Although rapamycin has a minimal effect on wild-type T cell expansion in vitro and in vivo, it completely suppresses the response of Pim-1(-/-)Pim-2(-/-) cells. Thus, endogenous levels of the Pim kinases are required for T cells to mount an immune response in the presence of rapamycin. The existence of a rapamycin-insensitive pathway that regulates T cell growth and survival has important implications for understanding how rapamycin functions as an immunomodulatory drug and for the development of complementary immunotherapeutics.

Cyclosporine: advantages versus disadvantages vis-à-vis tacrolimus

Despite a different molecular structure and biochemical properties, cyclosporine and tacrolimus--by inhibiting calcineurin activity--have been shown in the previous two decades of solid organ transplantation to be well tolerated and effective immunosuppressants. Initial randomized clinical trials showed a lower incidence of acute rejection in tacrolimus than in cyclosporine-treated patients, in combination with steroids and azathioprine. But in conjunction with mycophenolate mofetil, the difference in the incidence of acute rejection episodes is less clear. In general, short- and medium-term outcome variables (1-year serum creatinine, graft and patient survival) with cyclosporine and tacrolimus are excellent, and (almost) identical, with both substances having the same intrinsic nephrotoxic potential. On the other hand, cyclosporine and tacrolimus have a different impact on cardiovascular risk factors with tacrolimus having a better profile on arterial tension and lipid metabolism and cyclosporine on glucose metabolism. However, at present no data are available to discern that these differences in risk profile alter patient or graft survival or long-term cardiovascular morbidity/mortality. Therefore, prospective long-term trials are needed to study the quantitative impact of different immunosuppressive agents and concomitant cardiovascular risk factors on long-term patient and graft survival, before evidence-based (patient, graft, or cardiovascular) risk reduction can be firmly claimed by tailoring calcineurin inhibitors.

Topical pimecrolimus in the treatment of human allergic contact dermatitis

BACKGROUND

Contact dermatitis is a common clinical problem, with prevalent sensitizers being cosmetics, metals, medicines, and plants. Plants of the Toxicodendron species cause allergic contact dermatitis (ACD) in 50% to 70% of the population. Pimecrolimus is an ascomycin macrolactam developed for the treatment of inflammatory skin diseases and approved by the US Food and Drug Administration for atopic dermatitis. There are studies supporting the effectiveness of macrolactams when administered before antigen challenge, but there are no studies describing the effectiveness of these drugs in the treatment of established human ACD.

OBJECTIVE

To investigate the effect of topical pimecrolimus in the treatment of Toxicodendron-induced ACD once rash is evident.

METHODS

Poison ivy tincture was applied to the bilateral anterior forearms of 12 subjects with Finn Chambers (Allerderm Diagnostic Products, Petaluma, CA). After dermatitis was evident, volunteers treated each arm twice daily with either 1% topical pimecrolimus cream or placebo in a blinded fashion. Outcomes measured were a dermatitis grading score and time to rash and itch resolution.

RESULTS

The median +/- SEM time for rash resolution was 16.55 +/- 1.59 days in the treatment group and 16.27 +/- 1.82 days in the placebo group (P = 0.601). The median time for itch resolution was 4.73 +/- 1.56 days in the treatment group and 4.91 +/- 1.59 days in the placebo group (P = 0.167). The average dermatitis score was 2.26 +/- 0.17 in the treatment group and 2.32 +/- 0.15 in the placebo group (P = 0.62).

CONCLUSIONS

The application of topical pimecrolimus is ineffective in the treatment of ongoing Toxicodendron-induced ACD.

Influence of immunosuppressive drugs on dendritic cells

Immunosuppressive drugs used to control allograft rejection and in efforts to promote transplant tolerance are well recognized for their abilities to inhibit lymphocyte activation and proliferation. In recent years, evidence has accumulated that these diversely acting agents (anti-proliferative drugs, calcineurin inhibitors, rapamycin, deoxyspergualin and glucocorticoids) also affect the development and functional immunobiology of dendritic cells, in vitro and in vivo. Here we review the influence of immunosuppressive drugs on the differentiation and function of these important antigen-presenting cells. We also consider how these effects influence immune reactivity and tolerance induction, implications for furthermore understanding of dendritic cell biology and prospects for improving the outcome of organ transplantation and therapy of other immune-mediated disorders by impacting dendritic cell function.

Pimecrolimus inhibits the elicitation phase but does not suppress the sensitization phase in murine contact hypersensitivity, in contrast to tacrolimus and cyclosporine A

Pimecrolimus (SDZ ASM 981, Elidel) is a nonsteroid inflammatory cytokine inhibitor specifically developed for the treatment of inflammatory skin diseases. Its effect on the elicitation and sensitization phases of oxazolone-induced contact hypersensitivity was compared with tacrolimus and cyclosporine A (CyA) in BALB/c mice using the ear swelling assay. The compounds were administered orally. Elicitation was dose-dependently inhibited by all three compounds. The minimal effective doses were 30 mg per kg (pimecrolimus, tacrolimus) and 90 mg per kg (CyA), respectively. There was no impairment of sensitization by pimecrolimus up to the highest dose tested (120 mg per kg), in contrast to CyA (60% inhibition at 60 mg per kg) and tacrolimus (71% inhibition at 30 mg per kg). Weight and cellularity of the draining lymph nodes in mice treated with tacrolimus or CyA during sensitization were reduced. In addition, proliferation of T cells after secondary stimulation was inhibited in cell cultures from lymph nodes of mice treated with tacrolimus or CyA. Thus, in contrast to tacrolimus and CyA, pimecrolimus exerts a more selective immunomodulatory effect. It does not impair the primary immune response (sensitization phase) but effectively inhibits the secondary phase, the elicitation phase that is the clinical manifestation of contact hypersensitivity.

Inhibition of cytokine production and cytokine-stimulated T-cell activation by FK506 (tacrolimus)1

Insofar as it exerted its immunosuppressive effect by inhibiting cytokine expression, we assessed the effect of FK506 (Tacrolimus) on cytokine-stimulated T-cell activation. Human T cells, treated with FK506, or controls were stimulated with the mitogens PHA + PMA, Con A, and the "CD3-bypass" stimulation regimen, PMA + ionomycin. T-cell proliferation was quantitated by measuring the uptake of tritiated thymidine, and mRNA expression was assessed by RT-PCR. FK506, in a concentration-dependent fashion, inhibited T-cell proliferation and steady-state mRNA expression of IL-2 and IL-7; half-maximal suppression was obtained at 10(-7) to 5 x 10(-8) M. We tested whether FK506 antiproliferative effect could be overcome with exogenously reconstituted rIL-2 and/or rIL-7. Neither rIL-2 nor rlL-7, individually in conjunction with suboptimal concentrations of PHA or Con A, or in combination without any costimulus, was capable of abrogating FK506 antiproliferative effect, indicating that FK506 also acted by inhibiting cytokine-stimulated T-cell activation. To confirm this, T cells were treated with FK506 and stimulated by rIL-2 and rIL-7, individually in conjunction with suboptimal concentration of PHA and Con A. In addition, T cells were stimulated with rIL-2 and rIL-7 without any costimuli. FK506 inhibited T-cell activation stimulated by rIL-2 and by rIL-7, individually and in combination. This confirms that, in exerting its antiproliferative effect, FK506 acts at two levels, by inhibiting cytokine availability and by suppressing cytokine effect on target cells, and explains the beneficial effect of FK506 in attenuating ongoing immune responses.

Conditioned suppression of contact sensitivity is independent of sympathetic splenic innervation

The present study investigated the role of sympathetic innervation of the spleen in conditioned suppression of a contact hypersensitivity (CHS) reaction. Behavioral conditioning was achieved by pairing saccharin drinking solution (conditioned stimulus, CS) with injection of cyclosporin A (CsA, 20 mg/kg; unconditioned stimulus, UCS). Four days after sensitization of the animals by application of a 5% 2,4-dinitrochlorobenzene (DNCB) to abdominal skin, the animals were challenged by applying a 1% DNCB solution to the ear. The CHS response was monitored by measuring the degree of ear swelling. Saccharin re-presentation reduced ear swelling to a magnitude that approached that achieved by CsA treatment. Histological examination demonstrated that the conditioned reduction of ear swelling was produced by a reduced leukocyte infiltration of the ear. Prior sympathetic denervation of the spleen did not alter the conditioned suppression of the CHS response. These data indicate that behavioral conditioning using CsA produces alterations of CHS that, unlike conditioned prolongation of heart allograft survival, are independent of sympathetically regulated conditioned alterations in the spleen.

The effect of VAS972 on allergic contact hypersensitivity

BACKGROUND

Contact hypersensitivity (CHS) is a Th1-mediated immune response that can be down-regulated by immunosuppressive agents such as cyclosporine and environmental stimuli such as ultraviolet light. Recently, an immunomodulation therapy, VAS972, has been developed which is believed to down-regulate the Th1 arm of the immune response. This VAS972 involves modifying autologous blood by controlled exposure to the oxidizing agent ozone and UVC light, at an elevated temperature ex vivo. The processed blood is then administered by intramuscular injection.

OBJECTIVE

To further evaluate the immune modulating effect of VAS972.

METHODS

We examined the effect of VAS972 treatment on CHS. Contact hypersensitivity was induced with dinitrofluorobenzene (DNFB) in animals receiving VAS972- processed blood, control blood, or saline. A preliminary study was also conducted to evaluate the effect of plasma and cellular fractions of processed blood.

RESULTS

Mice injected with VAS972-processed blood demonstrated a significantly lower (46%) CHS response than controls. Histologic examination of challenged ear skin from control mice displayed edema with a significant lymphocytic infiltration, whereas animals administered processed blood demonstrated a reduction in lymphocytic infiltration. Mice injected with either plasma or the cellular fraction of the VAS972-treated blood also demonstrated a significant suppression (49% and 41%, respectively).

CONCLUSION

The results of this study demonstrated that VAS972 suppresses CHS and cellular infiltration. Furthermore, the plasma and cellular components of the VAS972 treatment were also able to induce immunosuppression. This further supports the hypothesis that VAS972 down-regulates the Th1 arm of the immune response.

Post-transplant epididymitis and orchitis following Listeria monocytogenes septicaemia

We report the occurrence of epididymitis and orchitis 1 week after the onset of Listeriosis in an 11-month-old boy receiving an orthotopic liver transplantation for biliary atresia. Immunologic implications of Listeria monocytogenes-induced testicular inflammation are discussed, and the potential role of immunosuppression with tacrolimus is also discussed.

Differential effects of cytokines and immunosuppressive drugs on CD40, B7-1, and B7-2 expression on purified epidermal Langerhans cells1

Langerhans cells are MHC class II antigen-positive antigen-presenting cells in the epidermis. Recent studies have revealed that Langerhans cells express costimulatory molecules like B7-1 and B7-2 and the accessory molecule CD40. Although these molecules are important for the antigen-presenting function of Langerhans cells, little is known about the precise regulation of their expression on purified Langerhans cells. Using a panning technique, we purified epidermal Langerhans cells to around 95% purity. Freshly prepared Langerhans cells (fLC) expressed the mRNA for receptors for M-CSF (cfms), GM-CSF (GM-CSFR), and TNF-alpha (TNFRII). TNF-alpha markedly upregulated CD40 and B7-1 expression on Langerhans cells, but not B7-2 expression. GM-CSF moderately upregulated B7-1 and B7-2 expression, and slightly upregulated CD40 expression. M-CSF moderately upregulated B7-1 expression, but did not modulate CD40 or B7-2 expression. Dexamethasone (DEX) markedly inhibited CD40, B7-1, and B7-2 expression on Langerhans cells. Cyclosporin A (CsA) and FK506 slightly inhibited CD40 and B7-1 expression on Langerhans cells, but not B7-2. Furthermore, TNF-alpha restored the DEX-induced inhibition of CD40 expression on Langerhans cells, but not the inhibition of B7-1 or B7-2 expression. GM-CSF restored DEX-induced inhibition of CD40, B7-1, and B7-2 expression. M-CSF did not affect the DEX-induced inhibition of these molecule expressions. These data provide a better understanding of the role of selective cytokines and immunosupressive drugs in the modulation of the antigen-presenting capacity of Langerhans cells.

Possible inhibitory mechanism of FK506 (tacrolimus hydrate) ointment for atopic dermatitis based on animal models

The effects of FK506 (tacrolimus hydrate) ointment on cutaneous allergic reactions in mice and rats were investigated. FK506 ointment showed significant suppressive effects on delayed allergic reactions in both species, and especially in rats, its inhibitory action was much stronger than that of alclometasone dipropionate, a so-called medium class steroid ointment. On the other hand, FK506 ointment did not inhibit the immediate allergic reaction in rats. FK506 ointment suppressed the delayed allergic reactions in locally passively sensitized mice to the same degree as that in actively sensitized mice. Accordingly, it is speculated that FK506 ointment inhibits the activation of sensitized T lymphocytes (Th1 cells) already accumulated in the dermis.