Immunosuppressive Effect Of Tacrolimus Research Articles

Immunosuppressive effects of mesenchymal stem cells on tacrolimus therapy in rat heart transplant model

Introduction: Mesenchymal stem cells (MSCs) are used in various clinical settings for effective cell therapy by taking advantage of their immunomodulatory, regenerative, and anti-inflammatory properties. We previously investigated the effects of the regenerative and anti-inflammatory properties of MSCs for consideration of their clinical application in organ transplantation. Since immunosuppressant agents are administered in nearly all clinical cases of organ transplantation, clarification of the immunological interaction between MSCs and the calcineurin inhibitor tacrolimus (TAC) is needed.Aim: Due to potential use of MSCs in organ transplantation, we assessed immunological interactions between TAC and MSCs in vivo.Methods: Adipose tissue-derived MSCs (AT-MSCs) were obtained from wild-type Lewis rats. We then used a rat heart transplantation model to observe the immunosuppressive effects of AT-MSCs, TAC, and those in combination. Following allogeneic heterotopic heart transplantation from ACI rats to Lewis rats, graft survival was assessed in groups treated with AT-MSCs, TAC, both, or neither.Results: Median survival of the allograft was 14.5 days in the TAC-alone group and 11 days in the MSC+TAC group. Although the difference between those groups was not significant, the survival periods of both were significantly longer as compared to that of the control (median survival =5 days, P<0.05) and MSC-alone (median survival =5 days, P<0.05) groups.Conclusions: Administration of AT-MSCs did not decrease the beneficial immunosuppressive effect of TAC on heart graft survival. TAC appears to be compatible and effective for clinical use as an immunosuppressant with AT-MSCs.

Age-Dependent Metabolic and Immunosuppressive Effects of Tacrolimus.

Immunosuppression in elderly recipients has been underappreciated in clinical trials. Here, we assessed age-specific effects of the calcineurin inhibitor tacrolimus (TAC) in a murine transplant model and assessed its clinical relevance on human T cells. Old recipient mice exhibited prolonged skin graft survival compared with young animals after TAC administration. More important, half of the TAC dose was sufficient in old mice to achieve comparable systemic trough levels. TAC administration was able to reduce proinflammatory interferon-γ cytokine production and promote interleukin-10 production in old CD4+ T cells. In addition, TAC administration decreased interleukin-2 secretion in old CD4+ T cells more effectively while inhibiting the proliferation of CD4+ T cells in old mice. Both TAC-treated murine and human CD4+ T cells demonstrated an age-specific suppression of intracellular calcineurin levels and Ca2+ influx, two critical pathways in T cell activation. Of note, depletion of CD8+ T cells did not alter allograft survival outcome in old TAC-treated mice, suggesting that TAC age-specific effects were mainly CD4+ T cell mediated. Collectively, our study demonstrates age-specific immunosuppressive capacities of TAC that are CD4+ T cell mediated. The suppression of calcineurin levels and Ca2+ influx in both old murine and human T cells emphasizes the clinical relevance of age-specific effects when using TAC.

Nordihydroguiaretic acid attenuates skin tumorigenesis in Swiss albino mice with the condition of topical co-administration of an immunosuppressant

Drug and chemically-induced immunosuppression has been implicated as a confounding factor for cancer development. Management of cancer in such situation is often a challenging task. We tested the efficacy of nordihydroguiaretic acid (NDGA) against immunosuppressant tacrolimus-induced augmentation of mouse skin tumorigenesis. It was observed that topical administration of tacrolimus significantly accelerated the tumor promotion events in dimethylbenz(a)anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA) promoted two-stage mouse skin carcinogenesis, which were accompanied by reduced CD4+/CD8+ ratio of lymph nodes and serum IL-2 level. NDGA pre-treatment before each TPA application reduced the tumor incidence, its multiplicity and volume together with improvement in histopathological alterations and decrease in proliferating cell nuclear antigen (PCNA) labeling index (LI). However, NDGA had no significant influence on the immunosuppressive effect of tacrolimus. The present study demonstrates chemopreventive effect of NDGA in normal as well as in the condition of immunosuppression. Thus, NDGA has the potential to inhibit or delay the onset of tumor development during immunosuppressive regimen.

Genetic Polymorphisms in ABCB1 Influence the Pharmacodynamic Effects of Tacrolimus on T Cells

Background: Tacrolimus (TAC) has a large interindividual variability in pharmacokinetics and quantification of its effect is difficult. TAC is a substrate of P-glycoprotein (P-gp; encoded by ABCB1), an efflux-pump which is expressed more on CD8+ T cells than on CD4+ T cells. Single-nucleotide polymorphisms (SNPs) are associated with interindividual differences in P-gp activity and hence may influence intralymphocytic TAC concentrations and efficacy, especially in CD8+ T cells. Here we studied the influence of SNPs in ABCB1 and of verapamil-induced P-gp inhibition on the biological effect of TAC on T cells. Methods: The influence of ABCB1 genotypes (3435CC/high pump-activity, CT, TT/low pump-activity) was studied in T cells of 16 healthy volunteers using P-gp-mediated rhodamine efflux (2 hours). The intracellular IL-2 expression in T-cell populations was measured after PMA/iono stimulation of whole blood by use of flowcytometry, in the presence of 10 ng/mL TAC and 40 nM verapamil. In addition, the relationship between ABCB1 SNPs, TAC-levels and ex vivo induced IL-2 production was studied in 37 TAC-treated renal transplant patients. Results: The mean rhodamine efflux was higher in CD8+ T cells compared to CD4+ T cells: 40% vs. 16%, respectively (P< 0.001). In healthy volunteers with the CC genotype 50% (95%-CI: 46-53%) of CD8+ T cells effluxed rhodamine which was significantly higher compared to the TT genotype (mean 39%; 95%-CI: 30-46%; P< 0.05). In the presence of the P-gp inhibitor verapamil, rhodamine was effluxed by only 0.8% of CD8+ T cells (95% CI: 0.3-1.4%), while TAC did not influence the efflux of rhodamine (mean 38%; 95%-CI: 35-42%). Blockade of P-gp by verapamil in the presence of TAC decreased the percentage of intracellular IL-2 producing CD8+ T cells by 14% suggesting an increased pharmacodynamic effect of TAC through prolonged intralymphocytic accumulation. In TAC-treated renal transplant patients with the CC genotype, verapamil reduced the percentage of IL-2 producing CD8+ T cells by 22% whereas no effect of verapamil was found in patients with the TT genotype. Moreover, the ratio TAC C0versus % IL-2 producing CD8+ T cells in CC genotype patients was significantly higher (P< 0.05) compared to TT genotype patients, showing that in CC-genotype patients, TAC has a smaller pharmacodynamic effect. Conclusion: Genetic polymorphisms in ABCB1 influence the P-gp activity of CD8+ T cells and the immunosuppressive effect of TAC in kidney transplant recipients.

Immunosuppressive effects of tacrolimus on macrophages ameliorate experimental colitis

Tacrolimus is a novel immunomodulator for inflammatory bowel diseases. Immunosuppressive effects of tacrolimus on T cells are well known; however, the effects of tacrolimus on macrophages remain unclear. The aim of this study was to investigate the effects of tacrolimus on activated macrophages and to examine its efficacy in murine colitis models. Proinflammatory cytokine production from lipopolysaccharide (LPS)-stimulated peritoneal macrophages of IL-10-knockout (KO) mice with and without tacrolimus was measured. We investigated the effects of tacrolimus on nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and caspase activation in macrophages and the induction of apoptosis in macrophages in vitro and examined the in vivo apoptotic effect of tacrolimus on colonic macrophages in IL-10-KO mice. We evaluated the effect of the rectal administration of tacrolimus on colonic inflammation in IL-10-KO mice and dextran sulfate sodium (DSS)-induced colitis in CB.17/SCID mice. Proinflammatory cytokine production from tacrolimus-treated macrophages was significantly lower than that from untreated cells. Tacrolimus suppressed LPS-induced activation of both NF-κB and MAPK in macrophages and induced apoptosis of macrophages via activation of caspases 3 and 9. Rectal administration of tacrolimus evoked apoptosis of colonic macrophages in IL-10-KO mice. Moreover, the rectal administration of tacrolimus ameliorated colitis in IL-10-KO mice and DSS-induced colitis in CB.17/SCID mice. Gene expression of inflammatory cytokines in colonic mucosa was significantly lower in tacrolimus-treated mice than in untreated mice. Tacrolimus suppresses the function of activated macrophages and promotes their apoptosis, which may lead to the amelioration of colonic inflammation.

Tacrolimus differentially regulates the proliferation of conventional and regulatory CD4(+) T cells.

Tacrolimus is a widely used T cell targeted immunosuppressive drug, known as a calcineurin inhibitor. However, the exact pharmacological effects of tacrolimus on CD4(+) T cells have yet to be elucidated. This study investigated the effects of tacrolimus on CD4(+) T cell subsets. Mouse or human CD4(+) T cells were cultured with immobilized anti-CD3/CD28 antibodies in the presence of tacrolimus. The cell division of CD4(+) T cells was analyzed using a flow cytometer according to the expression of Foxp3. The gene expression patterns of tacrolimus-exposed T cells were examined by quantitative PCR. In the case of conventional CD4(+) T cells (Tconv cells), tacrolimus inhibited T cell receptor stimulation-induced cell division. In contrast, the cell division of regulatory CD4(+) T cells (Treg cells) was even promoted in the presence of tacrolimus, especially in humans. Tacrolimus did not promote conversion of Tconv to Treg cells in mice. Furthermore, tacrolimus modified the expression levels of Foxp3-regulated T cell receptor signal related-genes, PTPN22 and Itk, in human Treg cells. Immunosuppressive effect of tacrolimus may be attributed to the relatively enhanced proliferation of Treg cells in association with altered gene expression levels of TCR signaling molecules.

同種造血幹細胞移植（Ａｌｌｏ‐ＳＣＴ）におけるタクロリムス内服時の薬物動態の解析と適正使用に向けた検討

Tacrolimus is an immunosuppressant which is usually administered to reduce the incidence of graft-versus-host-disease (GVHD) during allogeneic hemopoietic stem cell transplantation.The trough levels of tacrolimus are usually used as an index for monitoring pharmacokinetics and we conducted a pharmacokinetic analysis of the usefulness and validity of trough level monitoring following its oral administration.The mean bioavailability of tacolimus in 19 subjects was 34±14.1%.There appeared to be a statistically significant correlation between trough levels and the area under the curve (AUC) (AUCpo (0-12)=15.46×trough level-8.64,R2=0.92),and this correlation seemed to be little influenced by subject background or drug-drug interaction.Using our results we made a table for the conversion of trough levels to AUC,since the immunosuppressive effect of tacrolimus was considered to be correlated with the AUC.The conversion table will enable us to predict AUC values based on estimated target trough levels when switching the administration route from continuous instillation to oral administration,and will thus help ensure the appropriate use of tacrolimus in treatment.

Tacrolimus-induced neurotoxicity and nephrotoxicity is ameliorated by administration in the dark phase in rats.

1. Tacrolimus, a potent immunosuppressant, induces impaired renal function and neurological complications. We investigated the influence of dosing time on the neurotoxicity, nephrotoxicity, and immunosuppressive effect of tacrolimus in rats. 2. The repeated injection of tacrolimus in the light phase (8:00) produced a significantly greater increase than that in the dark phase (20:00) in the duration of harmine-induced tremors and in the blood urea nitrogen (BUN) concentration in rats. An immunosuppressive effect of tacrolimus on the xenotransplantation of mouse-to-rat skin grafts was apparent in the dark phase but not in the light phase. 3. The dosing time-dependent pharmacokinetic results were not observed when tacrolimus concentrations in rat whole blood were measured after a single or repeated injection in the light or dark phase. 4. These findings suggest that treatment in the active phase of the diurnal cycle ameliorates neurotoxicity and nephrotoxicity while maintaining the immunosuppressive effect of tacrolimus. The present findings have important implications for therapeutic approaches to avoid tacrolimus-induced neurotoxicity and nephrotoxicity.

Tacrolimus inhibits cytokine production and chemical mediator release following antigen stimulation of passively sensitized human lung tissues

The immunosuppressive effects of tacrolimus are mediated by inhibition of cytokine production by inflammatory cells. The role of tacrolimus on cytokine production and release of chemical mediators in asthma is not known at present. We compared the effects of tacrolimus on interleukin (IL)-5 and tumor necrosis factor-alpha (TNF-alpha) production and chemical mediator release from excised human lung tissue with those of steroids. Human lung tissue was passively sensitized with serum from atopic patients then preincubated with tacrolimus (10(-6), 10(-7), 10(-8) M) or dexamethasone (10(-6) M) for 2 hours. The lung tissue was then exposed to 1.5 microg/mL of mite antigen and then cultured for 48 hours. Culture supernatants were collected and IL-5 and TNF-alpha levels were measured by ELISA. IL-5 and TNF-alpha messenger ribonucleic acid (mRNA) expression was also investigated by reverse transcriptase-polymerase chain reaction. The level of histamine and leukotriene E4 was also measured in the culture supernatant. In addition, tryptase staining was performed to compare degranulation of mast cells. Antigen stimulation increased histamine and leukotriene release in the supernatant. Tacrolimus significantly and dose-dependently inhibited the release of histamine and leukotriene; dexamethasone did not. The results of tryptase staining demonstrated that tacrolimus dose-dependently inhibited degranulation of mast cells, whereas dexamethasone did not. Antigen stimulation increased TNF-alpha and IL-5 protein production and mRNA expression. Tacrolimus and dexamethasone significantly inhibited TNF-alpha and IL-5 protein production and mRNA expression. Our results indicated that tacrolimus is more powerful in inhibition of cytokine production and release of chemical mediators than steroids, and suggested that this immunosuppressor drug might be useful for the treatment of asthma.