Lymphokine gene expression in vivo is inhibited by cyclosporin A

Immunological advantages of everolimus versus cyclosporin A in liver-transplanted recipients, as revealed by polychromatic flow cytometry

Several immunosuppressive drugs with different mechanisms of action are available to inhibit organ rejection after transplant. We analyzed different phenotypic and functional immunological parameters in liver-transplanted patients who received cyclosporin A (CsA) or Everolimus (Evr). In peripheral blood mononuclear cells (PBMC) from 29 subjects receiving a liver transplant and treated with two different immunosuppressive regimens, we analyzed T cell activation and differentiation, regulatory T cells (Tregs) and Tregs expressing homing receptors such as the chemokine receptor CXCR3. T cell polyfunctionality was studied by stimulating cells with the superantigen staphylococcal enterotoxin B (SEB), and measuring the simultaneous production of interleukin (IL)-2 and interferon (IFN)-γ, along with the expression of a marker of cytotoxicity such as CD107a. The analyses were performed by polychromatic flow cytometry before transplantation, and at different time points, up to 220 days after transplant. Patients taking Evr had a higher percentage of total CD4⁺ and naïve CD4⁺ T cells than those treated with CsA; the percentage of CD8⁺ T cells was lower, but the frequency of naïve CD8⁺ T cells higher. Patients taking Evr showed a significantly higher percentage of Tregs, and Tregs expressing CXCR3. After stimulation with SEB, CD8⁺ T cells from Evr-treated patients displayed a lower total response, and less IFN-γ producing cells. The effects on the immune system, such as the preservation of the naïve T cell pool and the expansion of Tregs (that are extremely useful in inhibiting organ rejection), along with the higher tolerability of Evr, suggest that this drug can be safely used after liver transplantation, and likely offers immunological advantages.

Calcineurin/nuclear factor of activated T cells and MAPK signaling induce TNF-{alpha} gene expression in pancreatic islet endocrine cells

Cytokines contribute to pancreatic islet inflammation, leading to impaired glucose homeostasis and diabetic diseases. A plethora of data shows that proinflammatory cytokines are produced in pancreatic islets by infiltrating mononuclear immune cells. Here, we show that pancreatic islet α cells and β cells express tumor necrosis factor-α (TNF-α) and other cytokines capable of promoting islet inflammation when exposed to interleukin-1β (IL-1β). Cytokine expression by β cells was dependent on calcineurin (CN)/nuclear factor of activated T cells (NFAT) and MAPK signaling. NFAT associated with the TNF-α promoter in response to stimuli and synergistically activated promoter activity with ATF2 and c-Jun. In contrast, the β-cell-specific transcriptional activator MafA could repress NFAT-mediated TNF-α gene expression whenever C/EBP-β was bound to the promoter. NFAT differentially regulated the TNF-α gene depending upon the expression and MAPK-dependent activation of interacting basic leucine zipper partners in β cells. Both p38 and JNK were required for induction of TNF-α mRNA and protein expression. Collectively, the data show that glucose and IL-1β can activate signaling pathways, which control induction and repression of cytokines in pancreatic endocrine cells. Thus, by these mechanisms, pancreatic β cells themselves may contribute to islet inflammation and their own immunological destruction in the pathogenesis of diabetes.

Psoriasis of the nail: anatomy, pathology, clinical presentation, and a review of the literature on therapy

Psoriasis is a chronic skin disease that affects millions of people throughout the world. Even though cutaneous signs and symptoms are the most common clinical manifestations, the nails can be involved in up to 50% of cases, and their involvement remains an important yet often overlooked aspect of the disease. There is a broad spectrum of nail dystrophies associated with psoriasis, ranging from the common pitting and loosening of the nail plate to the less frequent discoloration and splinter hemorrhages seen in the nail bed. This article discusses the normal anatomy and embryology of the nail unit as well as the current understanding of the pathogenesis of the disease. It also provides an extensive review of the existing literature with respect to psoriatic nail therapy. Although there have been many recent advances in the treatment of the cutaneous form of the disease-most notably in the field of immunotherapies-the options for nail psoriasis are far more limited. While a number of treatment alternatives currently exist for nail disease, the general paucity of clear evidence regarding these choices often makes it difficult to select the most efficient, safe, and optimal treatment for the patient. Even though the current literature has shown some support for the use of topical, intralesional, radiation, systemic, and combination therapies for nail psoriasis, the available studies lack sufficient power to extrapolate a standardized therapeutic regimen. Therefore, until better-documented evidence validating the treatment options emerges within the literature, clinicians and patients are left with a vague and relatively unproven approach to psoriatic nail disease.

Mice deficient in PKC theta demonstrate impaired in vivo T cell activation and protection from T cell-mediated inflammatory diseases

In the present study we have characterized T cell-driven immune function in mice that are genetically deficient in PKC theta. In response to simple immunologic stimulation invoked by in vivo T cell receptor (TCR) cross-linking, these mice showed significantly depressed plasma cytokine levels for IL-2, IL-4, IFNgamma, and TNFalpha compared to wild-type (WT) mice. In parallel, spleen mRNA levels for these cytokines were reduced, and NF-kappaB activation was also reduced in PKC theta knockouts (KO). Injection of allogeneic cells into the footpad of PKC theta deficient mice provoked a significantly diminished local T cell response compared to WT mice similarly challenged. Unlike comparable cells from wild type mice, CD45RBhi T cells harvested from PKC theta deficient mice failed to induce colitis in the SCID-CD45RB cell transfer model of IBD. In another T cell-dependent model of inflammatory disease, PKC theta deficient animals developed far less severe neurologic signs and reduced spinal cord inflammatory cell infiltrate compared to WT controls in the MOG-induced EAE model. A fundamental role for PKC theta in T cell activation and in the development of T cell-mediated inflammatory diseases is indicated by these results.

JTP-27536 [(+)-1,3-dihydroxy-2-hydroxymethylpropyl-2-ammonium 2-[(R)-3-cyclo-hexyl-1-phenylpropyl]-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carboxylate monohydrate], a novel inhibitor of immunoglobulins and interleukin-5 with anti-inflammatory properties in mouse allergic dermatitis model

We report a novel synthetic compound JTP-27536 [(+)-1,3-dihydroxy-2-hydroxymethylpropyl-2-ammonium 2-[(R)-3-cyclohexyl-1-phenylpropyl]-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carboxylate monohydrate] as an inhibitor of immunoglobulins (Igs) and interleukin (IL)-5 production in vitro and in vivo. JTP-27536 inhibited IgE production in mouse and human B cells with IC50 values of 2.5 and 2.1 microM, respectively, and the inhibition was stronger than that on IgG1 and IgM production (IC50 > 10 microM). JTP-27536 also inhibited IL-5 production in mouse splenocytes and human peripheral blood mononuclear cells with IC50 values of 3.3 and 1.3 microM, respectively, without affecting mouse interferon (IFN)-gamma, IL-2, IL-4, IL-10, or human IL-4 production. In contrast, prednisolone not only inhibited mouse IgE production but also mouse IFN-gamma, IL-2, IL-4, and IL-10 and human IL-4 and IL-5 production in vitro. The effect of suplatast tosilate, a Th2 cytokine inhibitor, on antibody and cytokine production was less potent than that of JTP-27536. In vivo animal experiments using dinitrophenylated ascaris-sensitized mice and 2,4,6-trinitro-1-chrolobenzene-induced chronic dermatitis mice showed that JTP-27536 was more potent than suplatast tosilate and comparable with prednisolone in inhibiting ear swelling, antigen-specific IgE and IL-5 production, and cell infiltrations into the inflamed tissue. These results indicate that JTP-27536 is an inhibitor of Igs, in particular IgE, and of IL-5, which has antiallergic properties in mouse dermatitis model, and suggest that an inhibitor of Igs and IL-5 like JTP-27536 may be useful as a drug for the treatment of allergic diseases.

Cyclosporin A therapy differently affects immunological-relevant gene expression following immunization

We have studied the effect of cyclosporin A (CSA) on the expression of genes involved in the immune response in mice bearing a transgenic T cell receptor specific for the peptide 88-104 of the pigeon cytochrome c. Immunization of mice treated with CSA resulted in the blockade of the IL2, IFN-gamma, CXCR-5, CCR-5 and CD25 gene transcription. CSA decreased the density of CD69 on T-cells but did not interfere with the induction of the chemokine receptors CCR-1, CCR-4, CXCR2 and CXCR-4. Finally, CSA accelerated the kinetics of CD44 and CD62L expression or re-expression and increased the density of both markers on T-cell membrane. The present data show that priming in presence of CSA resulted in the acquisition of a particular phenotype by the activated T-cells.

Psoriasis. Immunopathology and immunomodulation

Biologics in development for the treatment of moderate to severe plaque-type psoriasis are discussed in this article. Immunomodulators used as therapeutic, pathogenic probes will continue to identify targets that play primary roles in the pathogenesis of psoriasis.

Lipid-mediated ex vivo gene transfer of viral interleukin 10 in rat lung allotransplantation

BACKGROUND

Recent studies suggest that viral interleukin 10 suppresses alloimmune response in transplantation and that cationic lipids are one of the most promising nonviral vehicles for gene therapy. The aim of this study was to examine the effect of ex vivo lipid-mediated viral IL10 gene transfer into rat lung allografts on subsequent rejection.

METHODS

Male F344 rats (RT1lvl) underwent left lung transplantation with allografts from Brown Norway rats (RT1n). Allografts were transvascularly transfected 15 minutes after harvest with 5 mL of 1:20-diluted (group 1, n = 7) or 1:40-diluted (group 2, n = 6) GL67-pCMVievIL-10 complex. Group 3 (n = 7), serving as the control group, received 1:40-diluted GL67-pCF1-chloramphenicol acetyltransferase complex. All allografts were preserved for 3 hours at 10 degrees C before transplantation. In all groups recipients were killed on postoperative day 5. Transgene expression of viral interleukin 10 was assessed by means of both reverse transcriptase-polymerase chain reaction and immunohistochemistry. Histologic rejection score, allograft gas exchange, exhaled nitric oxide level, and allograft cytokine mRNA expression were also assessed.

RESULTS

Dose-dependent transgene expression of viral interleukin 10 was detected by means of both reverse transcriptase-polymerase chain reaction and immunohistochemistry. Allograft gas exchange (PaO2) in groups 1 (114.06 +/- 61.1 mm Hg) and 2 (108.58 +/- 35.7 mm Hg) was significantly better than that in group 3 (66.4 +/- 8.22 mm Hg; P =.020 and P =.023, respectively). The vascular rejection score in group 1 was significantly lower than that in group 3 (P =.032, Kruskal-Wallis test). Exhaled nitric oxide levels in group 2 (5.150 +/- 6.38 ppb) were significantly lower than those in group 3 (13.517 +/- 10.4 ppb; P =.039). Allograft interleukin 2 mRNA expression levels in group 1 (1.123 +/- 0.23 relative units) were significantly lower than those in group 3 (1.753 +/- 0.71 relative units; P =.038 vs group 3).

CONCLUSIONS

Lipid-mediated ex vivo viral IL10 gene transfer into rat lung allografts improved graft gas exchange, reduced histologic rejection scores, downregulated graft interleukin 2 mRNA expression, and reduced exhaled nitric oxide levels by postoperative day 5. These results suggest a therapeutic potential of graft viral IL10 gene transfer as an effective immunosuppressive strategy against lung allograft rejection.

Serum levels of soluble IL-2 receptor, IL-12, IL-18, and IFN-gamma in patients with acute graft-versus-host disease after allogeneic bone marrow transplantation

BACKGROUND

Acute graft-versus-host disease still represents the major factor that limits successful allogeneic bone marrow transplantation. Cytokines released by type 1 T-helper cells are thought to play a pivotal role in acute graft-versus-host disease.

OBJECTIVE

This study was performed to investigate whether the serum levels of soluble IL-2 receptor, IL-12, IL-18, and IFN-gamma were associated with the manifestation of acute graft-versus-host disease.

METHODS

Serum cytokine levels were measured by sandwich ELISA in 18 patients who underwent allogeneic bone marrow transplantation.

RESULTS

Serum levels of soluble IL-2 receptor, IL-12, IL-18, and IFN-gamma were increased in patients in whom acute graft-versus-host disease developed. However, only serum soluble IL-2 receptor levels were significantly related to disease severity. Serum levels of IL-12 and IL-18, both of which are mainly produced by activated macrophages, were increased in different phases of acute graft-versus-host disease, especially grade I. Serum levels of soluble IL-2 receptor and IFN-gamma were significantly elevated in patients with fever.

CONCLUSION

Serum levels of soluble IL-2 receptor were more closely related to the severity of acute graft-versus-host disease than those of IL-12, IL-18, and IFN-gamma.

Development of the murine and human immune system: differential effects of immunotoxicants depend on time of exposure

Fetal and early postnatal life represent critical periods in vertebrate immune system development. Disruption of such development by perinatal immunotoxic chemical exposure has been widely described in experimental animal models. The resultant inhibited postnatal immune responses in such animals are often more dramatic and persistent than those after exposure during adult life. Further, recent reports suggest that prenatal exposure to immunotoxicants may exacerbate postnatal aberrant immune responses (e.g., hypersensitivity disorders and autoimmune disease) in genetically predisposed rodents. Limited information is available regarding the possibility of inhibited postnatal immune capacity in humans as a result of developmental immunotoxicant exposure. The multifactorial nature of hypersensitivity and autoimmune responses will further complicate the elucidation of possible relationships between chemical exposure during ontogeny of the human immune system and immune-mediated disease later in life. Taken together, however, the available animal data suggest the potential for altered postnatal immune function in humans exposed to immunotoxicants (e.g., environmental chemicals and therapeutic agents) during fetal and/or early postnatal life.

Development of the murine and human immune system: differential effects of immunotoxicants depend on time of exposure

Fetal and early postnatal life represent critical periods in vertebrate immune system development. Disruption of such development by perinatal immunotoxic chemical exposure has been widely described in experimental animal models. The resultant inhibited postnatal immune responses in such animals are often more dramatic and persistent than those after exposure during adult life. Further, recent reports suggest that prenatal exposure to immunotoxicants may exacerbate postnatal aberrant immune responses (e.g., hypersensitivity disorders and autoimmune disease) in genetically predisposed rodents. Limited information is available regarding the possibility of inhibited postnatal immune capacity in humans as a result of developmental immunotoxicant exposure. The multifactorial nature of hypersensitivity and autoimmune responses will further complicate the elucidation of possible relationships between chemical exposure during ontogeny of the human immune system and immune-mediated disease later in life. Taken together, however, the available animal data suggest the potential for altered postnatal immune function in humans exposed to immunotoxicants (e.g., environmental chemicals and therapeutic agents) during fetal and/or early postnatal life.

Cytokine gene polymorphisms predict acute graft rejection following renal transplantation

BACKGROUND

The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of acute rejection, while animal models suggest a role for interleukin-10 (IL-10) in promoting graft survival. It has also been shown that polymorphisms in the TNFA gene promoter (position -308) and in the IL-10 gene promoter (position -1082) correlate with differential production of these cytokines in vitro. The aim of this study was to determine whether TNF-alpha and IL-10 gene polymorphisms influence the incidence and severity of acute rejection in the first six months following renal transplantation.

METHODS

The cytokine genotypes of 115 consecutive first cadaveric kidney allograft recipients and their donors were screened. The rejection episodes (REs) were defined clinically and confirmed histologically where possible and further classified according to severity (RS), namely steroid-resistant or responsive REs. The genotypes were then correlated with the REs and RS.

RESULTS

The recipient TNF-alpha high producer genotype and IL-10 high producer genotype were significantly associated with multiple REs (>/=2) in human leukocyte antigen (HLA)-DR mismatched transplants (P = 0.0047 and P = 0.045, respectively), whereas only the TNF-alpha high producer genotype was associated with steroid-resistant REs (P = 0.025). When recipient cytokines were analyzed together, the TNF-alpha high/IL-10 high producer genotype had the worst prognosis, whereas TNF-alpha low/IL-10 low producer genotype was protective.

CONCLUSIONS

We conclude that recipient TNF-alpha and IL-10 gene polymorphisms are determinants of REs and RS following kidney transplantation. Routine screening of these gene polymorphisms may have a clinical role in identifying patients at risk of multiple REs and severe rejections.

Cytokine mRNA expression in tolerant heart allografts after immunosuppression with cyclosporine, sirolimus or brequinar

We sought to examine the impact of the preferential activation of Th2 cells on the induction and maintenance of a tolerant state in heart allograft rat recipients treated with a short course of cyclosporine (CsA), sirolimus (SRL) or brequinar (BQR). A quantitative polymerase chain reaction (PCR) method was used to measure the levels of cytokine mRNAs, namely interferon (IFN)-gamma and interleukin (IL)-2 in T helper 1 (Th1) cells and IL-4, IL-5 and IL-10 in Th2 cells. Our main findings were that on day 5 postgrafting allografts from untreated recipients had increased levels of IFN-gamma (216 +/- 119 fg), IL-2 (449 +/- 75 fg), IL-4 (6.2 +/- 1.3 fg), IL-5 (34.8 +/- 9.3 fg) and IL-10 (1554 +/- 184 fg) mRNAs compared with normal hearts. CsA reduced the levels of IFN-gamma, IL-2, IL-5 and IL-10, but not IL-4, mRNAs. SRL did not affect the expression of cytokine mRNAs. BQR decreased the levels of IFN-gamma, IL-2 and IL-10, but not IL-5 or IL-4 mRNAs. Compared with grafts from untreated recipients, those from CsA- or BQR-treated tolerant hosts (day 100) displayed undetectable IL-2 mRNA levels, and reduced levels of IFN-gamma, IL-4 and IL-10 mRNAs. In fact, the patterns of cytokine mRNA expression in grafts from CsA- and BQR-treated tolerant hosts were similar to those of normal hearts. Grafts from SRL-treated tolerant hosts merely showed slightly increased Th2 cell activity. In conclusion the selective activation of Th2 cells is not absolutely required for induction or maintenance of tolerance.

Effects of cyclosporine A and methotrexate on induction of tumour necrosis factor-alpha in rat cardiac allografts

Experimental and clinical studies have yet to determine the extent to which methotrexate (MTX) or cyclosporine A (CSA) treatment alone affects the expression in vivo of tumour necrosis factor-alpha (TNF alpha), a cytokine produced primarily by macrophages and believed to be directly involved in the pathogenesis of cardiac allograft rejection. In light of previously published findings from this laboratory examining the effects of combination CSA/MTX treatment, these studies were designed to examine the individual effects of CSA and MTX upon TNF alpha gene expression post-transplant (post-tx) using an accessory cervical heart transplant model in the rat. These studies have focused on a highly sensitive method with which to detect changes in gene expression, reverse transcriptase-polymerase chain reaction (RT-PCR) methodology and enzyme-linked immunosorbent assay (ELISA) assessment of transplant TNF alpha protein levels. Both techniques consistently demonstrated biphasic TNF alpha expression in cardiac transplant tissue obtained from untreated allograft recipients during the first week post-tx in contrast to isograft recipients. Previously demonstrated in combination to prolong cardiac allograft survival, low-dose MTX and low-dose CSA were each evaluated alone in the course of these studies to determine their impact on TNF alpha gene expression. While TNF alpha levels were up-regulated during untreated allograft rejection, both TNF alpha RNA and protein were significantly diminished with low-dose combination CSA/MTX treatment, with CSA alone, but not significantly with MTX treatment alone. In conclusion, TNF alpha gene expression in untreated allografts is consistent with the hypothesis that TNF alpha may play a role in events leading to allograft rejection. Results of these studies indicate that TNF alpha levels are significantly regulated in vivo by CSA but not by MTX treatment. These studies further implicate a role for low-dose MTX in mediating statistically significant immunosuppressive effects in conjunction with low-dose CSA.

Transcription factors of the NFAT family: regulation and function

As targets for the immunosuppressive drugs cyclosporin A and FK506, transcription factors of the NFAT (nuclear factor of activated T cells) family have been the focus of much attention. NFAT proteins, which are expressed in most immune-system cells, play a pivotal role in the transcription of cytokine genes and other genes critical for the immune response. The activity of NFAT proteins is tightly regulated by the calcium/calmodulin-dependent phosphatase calcineurin, a primary target for inhibition by cyclosporin A and FK506. Calcineurin controls the translocation of NFAT proteins from the cytoplasm to the nucleus of activated cells by interacting with an N-terminal regulatory domain conserved in the NFAT family. The DNA-binding domains of NFAT proteins resemble those of Rel-family proteins, and Rel and NFAT proteins show some overlap in their ability to bind to certain regulatory elements in cytokine genes. NFAT is also notable for its ability to bind cooperatively with transcription factors of the AP-1 (Fos/Jun) family to composite NFAT:AP-1 sites, found in the regulatory regions of many genes that are inducibly transcribed by immune-system cells. This review discusses recent data on the diversity of the NFAT family of transcription factors, the regulation of NFAT proteins within cells, and the cooperation of NFAT proteins with other transcription factors to regulate the expression of inducible genes.

Alloantibody and intragraft cellular response to MHC class I-disparate kidney allografts in recipients tolerized by donor-specific transfusion and cyclosporine

Congenic PVG.RT1u rats rapidly reject Aa class I-disparate kidney allografts from recombinant PVG R8 donors and we recently demonstrated that anti-class I MHC alloantibody plays a critical role in effecting acute rejection in this experimental model. In this article, we show that PVG.RT1u recipients can be rendered permanently and specifically tolerant to R8 kidney allografts by administration of four weekly donor-specific transfusions (DST) combined with a 7-day course of cyclosporine given with the first DST. Tolerance induction correlated with abrogation of a cytotoxic alloantibody response by thymus-independent, i.e., peripheral mechanisms; IgM and all IgG subclasses of anti-class I alloantibody were abolished. In contrast, nonrejecting kidney allografts in tolerant rats and rejecting grafts from unmodified recipients were similarly infiltrated by mononuclear cells, and intragraft transcripts for interleukin (IL)-2, interferon-gamma, and IL-13 were readily detected by reverse transcriptase polymerase chain reaction with no apparent quantitative difference between the two groups. Messenger RNA for IL-4 and IL-10 was present in rejecting grafts but barely detectable in grafts from tolerant animals. These results suggest that tolerance induction by DST and cyclosporine is, in this experimental model, associated with a selective impairment in humoral alloimmunity.

Triple drug immunosuppression significantly reduces aortic allograft arteriosclerosis in the rat

We evaluated the effect of triple drug immunosuppression (cyclosporine A 10 mg . kg(-1) . d(-1), methylprednisolone 0.5 mg . kg(-1) . d(-1) on the development of allograft arteriosclerosis (chronic rejection). The recipients of rat aortic allografts from the DA (AG-B4,RT1a) to the WF (AG-B2,RT1u) strain were either treated with triple drug immunosuppression (n=23) or left untreated (n=23) and used as controls. The grafts were removed 7, 14, 30, 90, and 180 days after transplantation, and vascular wall changes were evaluated by quantitative histology, [3H]thymidine autoradiography, and immunohistochemistry. Nonimmunosuppressed aortic allografts developed progressive arteriosclerotic alterations 1 to 6 months after transplantation that were virtually identical to those observed during chronic rejection in human cardiac allografts. Linear regression analysis revealed that triple drug immunosuppression with clinically relevant dosages of drugs significantly reduced intimal thickening (r=.69 versus r=.88, P<.05). Concomitantly, there was a marked reduction in the number of inflammatory cells (P<.01) and their rate of proliferation (P<.025) in the allograft adventitia during the period of acute inflammation (30 days after transplantation). Immunohistochemistry revealed that the number of helper T cells (W3/25) and monocyte/macrophages (OX42) but not cytotoxic T cells (OX8) or natural killer cells (3.2.3) was significantly (P<.05) reduced. The number of adventitial cells expressing interleukin-2 receptor (CD25) (P<.05), MHC class II (OX6) (P<.05) and leukocyte function-associated antigen-1 alpha-chain (CD11a) (P<.025) was also significantly reduced at 30 days. Triple drug immunosuppression downregulated the induction of MHC class II and intercellular adhesion molecule-1 on the graft endothelium but had no significant effect on the number of subendothelial inflammatory cells. In addition, [3H]thymidine autoradiography demonstrated that triple drug immunosuppression significantly reduced the rate of cell proliferation in the media, composed of smooth-muscle cells, 30 and 90 days after transplantation. Thus, triple drug immunosuppression efficiently reduced the development of allograft arteriosclerosis by down-regulating the inflammatory response and the level of immune++ activation in the allograft adventitia during the acute rejection period, resulting in diminished intimal thickening of the graft in the long run. These results support the concept that allograft arteriosclerosis is due to or at least initiated by immune injury of the graft.

Identification of a calcium-inducible, cyclosporine sensitive element in the IFN-gamma promoter that is a potential NFAT binding site

Cyclosporine (CsA) inhibits cytokine transcription by preventing the activation of key promoter sites, in particular the binding of nuclear factor of activated T cells (NFAT) to the IL-2 NFAT site and the "P" site in IL-4. To identify potential NFAT-like sites in the IFN-gamma promoter, we sought areas of homology with the known sites in other promoters. In the promoter region of the mouse and human IFN-gamma gene, we identified two repeats of a consensus sequence ATTTCCnnT, designated P1 and P2 because of their homology to the calcium-inducible and CsA-sensitive "P" sequences in the IL-4 promoter. In electrophoretic mobility shift assay (EMSA), a probe containing the second P sequence "P2" in the human IFN-gamma gene bound nuclear proteins from stimulated, but not unstimulated, humans T cells. The cytosol of unstimulated cells contained similar binding activity that decreased after stimulation, indicating that this binding activity translocated to the nucleus after stimulation. CsA inhibited nuclear translocation. Competition studies demonstrated that oligomers containing the sequences P1 and P2 in IFN-gamma gene, the NFAT site in the IL-2 gene, and the IL-4 P site competed with the P2 probe for protein binding, whereas an oligomer containing mutations in the P2 site did not. Addition of anti-NFAT antiserum altered protein binding to P2, indicating that the proteins were either identical or related to NFAT. Stimulation of T cells transfected with constructs containing three copies of the P2 sequence enhanced CAT activity in response to ionomycin, and this effect was blocked by CsA. These results suggest that the P2 sequence, and probably the P1 sequence, in the IFN-gamma promoter are NFAT binding sites and contribute to the calcium inducibility and CsA sensitivity of IFN-gamma production.

An immunohistochemical study of topical cyclosporine in vernal keratoconjunctivitis

PURPOSE

To determine the immunomodulating effects of topical cyclosporine on the immune cells in the conjunctival biopsy specimens obtained from patients with active vernal keratoconjunctivitis.

METHODS

We studied six patients who had severe active vernal keratoconjunctivitis. Each patient was given topical cyclosporine 2% eyedrops four times daily. A 2 x 2-mm limbal conjunctival biopsy specimen was obtained from each patient before and three weeks after treatment. Using a panel of monoclonal and polyclonal antibodies and immunohistochemical techniques, we analyzed the conjunctival immune cells before and after cyclosporine treatment.

RESULTS

Three weeks after topical cyclosporine treatment, there was marked clinical improvement and a statistically significant reduction in the number of epithelial and stromal class II MHC+ cells, UCHL1+ T cells, and stromal IgA+ and IgG+ plasma cells. The mean number of cells before and after therapy, respectively, were: class II MHC+ (epithelium), 31.5 +/- 13.1 and 8.3 +/- 5.6 (P = .031); class II MHC+ (stroma), 77.0 +/- 28.7 and 24.7 +/- 17.5 (P = .031); UCHL1+ T cells (epithelium), 24.5 +/- 14.1 and 4.2 +/- 2.9 (P = .031); UCHL1+ T cells (stroma), 78.7 +/- 31.1 and 44.5 +/- 27.5 (P = .031); IgA+ plasma cells, 66.7 +/- 32.1 and 22.2 +/- 7.8 (P = .031); and IgG+ plasma cells, 37.3 +/- 30.0 and 9.0 +/- 6.4 (P = .031). There was a statistically insignificant decrease in the epithelial class II MHC+ dendritic Langerhans cells, epithelial and stromal KP1+ macrophages, stromal OPD4+ helper/inducer T cells, and stromal L26+ B cells. The numbers of IgE+ plasma cells and mast cells were unaltered.

CONCLUSION

The clinical improvement in vernal keratoconjunctivitis after topical cyclosporine therapy may result from its immunomodulating effect on the components of cell-mediated and humoral immune responses. In contrast, the drug has no immunomodulatory effect on mast cells and IgE-mediated allergic response.

Innovative treatment approaches for rheumatoid arthritis. Cyclosporin, leflunomide and nitrogen mustard

Cyclosporin A (CSA) Cyclosporin inhibits IL-2 release and T-cell activation and, secondarily, affects B-cell function. It also inhibits bone resorption, at least in vitro. This drug's bio-availability averages 25-35% but is highly variable. Food and grapefruit juice enhance bio-availability and newer formulations may make its absorption more reliable. It is highly concentrated in fatty tissues and red blood cells but does not cross the blood-brain barrier. CSA is metabolized to numerous metabolites by the liver and its elimination half-life is 6-12 hours in the absence of severe liver disease. Biliary excretion accounts for 94% of CSAs elimination. Because it is highly metabolized, its metabolism can be inhibited by other drugs (e.g. ketoconazole and erythromycin) or its metabolism can be induced (e.g. anticonvulsants). Cyclosporin is more effective than placebo for the treatment of rheumatoid arthritis and as effective as other antirheumatics. There is potential for the use of CSAs in DMARD combinations. The principal toxicities of cyclosporin are gastro-intestinal and renal, with the latter being of more concern. Leflunomide (LF). Leflunomide may be a pyrimidine synthesis inhibitor, although tyrosine kinase inhibitor may also be part of its mechanism of action. Its active metabolite is excreted renally to a large degree, with a prolonged elimination half-life of about 11 days. Since LF is activated by liver metabolism, renal failure may have less effect on kinetics than severe liver disease. Early data on efficacy indicate efficacy at 10-25 mg/day, although more well-controlled data is necessary. Toxicity relates to the skin, liver and GI tract, although some degree of weight loss was also found. Nitrogen mustard (NM). Nitrogen mustard is an alkylating agent whose pharmacokinetics are poorly understood. Small, open studies in RA indicate that NM has a potential for relatively rapid response (1-2 weeks) but, clearly, much work remains to be done. As an alkylating agent, GI and hematological toxicities are of greatest concern.

Immunopathogenesis and immunotherapy in rheumatoid arthritis: an area in transition

In years to come, new therapeutic modalities for the treatment of chronic arthritis will be launched for general clinical use. These therapies, until today only used in clinical studies, are based on knowledge obtained from animal models of chronic arthritis. This knowledge not only ushers therapeutic use in humans: in many settings, the animal studies have proven to be irreplacable tools to get insights into the pathogenesis of chronic arthritis. Rheumatoid arthritis (RA) shows a strong linkage of susceptibility to a certain epitope common to some HLA-DR beta chains; this immunogenetic linkage is the strongest evidence for specific, T-cell dependent immunity in the pathogenesis of the disease. Despite intense efforts, no unequivocal proofs of T-cell specificity or oligoclonality have been found in RA. Therapeutic efforts directed against T-cells or T-cell functions have also at the best showed partial effects. As compared to the local production of T-cell cytokines in the joint, monokine production is abundant. Therapies aimed at neutralizing the effects of the cartilage-devastating monokine TNF-a have showed remarkable results in small clinical trials. The possibility of increasing the presence of the regulatory cytokines IL-4, IL-10 and TGF-beta has also been explored, but only in animal studies. Immunology has also shed light on the mode of action of the commonly used 'disease modifying' drugs, and combinations of such drugs have shown increased potentials in recent clinical studies. The possibility of combining traditional anti-arthritic drugs with recent immunological tools seem promising for the future. This review discusses recent advances in the understanding of pathogenesis and delineate new therapeutic approaches for chronic arthritis from the point of view of the immunologically oriented clinician.

Cyclosporine inhibition of calcineurin activity in human leukocytes in vivo is rapidly reversible

Despite increasing information about the mechanism of action of cyclosporine A (CsA), little is known about the way lymphocytes recover from CsA. Recovery is central to understanding the pharmacodynamics of CsA in vivo. We studied the recovery of calcineurin phosphatase (CN) activity in CsA-treated cells. Single dose kinetics in renal transplant patients showed that inhibition of CN activity in PBL increased and fell concomitant with CsA blood vessels. In vitro, control PBL treated with CsA 100 micrograms/l, washed, and resuspended in CsA-free medium showed little recovery (0-20%) after 24 h. Erythrocytes or anti-CsA Ab added to the recovery medium increased recovery to 50% within 4 h. Similar recovery was seen in the ability of cells to produce IFN-gamma after OKT3 stimulation. Recovery of CN activity was associated with the efflux of [3H]CsA, was not blocked by cycloheximide and was temperature sensitive. A cell line with high expression of surface P glycoprotein (PGP), showed rapid recovery. However, PGP blockade did not prevent recovery in PBL, indicating a different PGP-independent mechanism. In PBL, recovery from CsA is slow and limited in vitro, but rapid in vivo, where CsA equilibrates among a complex set of extralymphocytic binding sites.

The sigma ligand SR 31747 prevents the development of acute graft-versus-host disease in mice by blocking IFN-gamma and GM-CSF mRNA expression

SR 31747 is a sigma ligand which prevents the development of acute graft-versus-host reaction (GvHR) in hybrid B6D2F1 mice injected with C57BL/6 parental spleen cells. In the present study, we showed that this drug dramatically impaired the GvHR-associated increase in the numbers of both B-lymphocytes and polymorphonuclear cells (PMNs) in the spleen. Because SR 31747 blocked the GvHR-induced expression of both interleukin-2 and transferrin receptors on T-lymphocytes, it is very likely that this molecule prevented the disease through an inhibition of T-lymphocyte activation. Cytokine messenger RNA analyses on spleen cells revealed that SR 31747 blocked IFN-gamma and GM-CSF but not IL-4 transcription. These effects, which are different from those observed with either cyclosporin-A or dexamethasone, strongly suggest that SR 31747 preferentially inhibits the Th1 lymphocyte subset.

Cytokine gene expression after allogeneic bone marrow transplantation

Cytokines produced by T lymphocytes, monocytes/macrophages, and fibroblasts play a central role in the immune response and in the development of graft-versus-host disease (GVHD). Also, it has been reported that dysregulated production of cytokines maybe the primary mediator of clinical manifestation of acute GVHD. Regarding cytokine gene expression after human allogeneic bone marrow transplantation (allo BMT), we have demonstrated increased IL-1 beta, IL-6, and TNF-alpha mRNA expression in peripheral blood mononuclear cells during the development of acute and chronic GVHD and that the degree of the increase was dependent on the severity of the disease. Furthermore, overexpression of these cytokine mRNAs could be detected before the clinical manifestations of GVHD developed. In contrast, IL-2 mRNA expression was not detected in peripheral blood mononuclear cells in GVHD patients. On the other hand, we have reported that increased mRNA expression and protein product of IL-2 and IFN-gamma were evident in the mixed lymphocyte culture of the cases who developed severe lethal transplantation-related complications. Therefore, the detection of increased IL-2 and IFN-gamma gene expression in MLC appeared to be useful for predicting transplantation-related complications in BMT patients. Furthermore, we found increased IL-2 receptor alpha subunit mRNA expression in the peripheral blood mononuclear cells during GVHD. These findings may indicate the important role of inflammatory cytokines such as IL-1 beta, IL-6 and TNF-alpha in the development of the clinical manifestation of GVHD and also may be indicative of the important role of IL-2 and the IL-2 receptor in allo response perhaps mainly as an autocrine effect.(ABSTRACT TRUNCATED AT 250 WORDS)

International consensus recommendations on cyclosporin use in rheumatoid arthritis

Guidelines for the use of cyclosporin in patients with rheumatoid arthritis have been formulated as a result of 2 International Consensus meetings. Clinical experience since the last meeting in June 1994 indicates that the clear and simple recommended guidelines remain valid. Experience in early identification of patients with a poor prognosis is growing, and trials currently underway will provide further evidence regarding the use of cyclosporin earlier in the course of severe disease. Confirmation of the potential benefits of the microemulsion-based formulation of cyclosporin (Neoral) relative to the conventional formulation (Sandimmun) will further strengthen the position of the drug in the management of patients with rheumatoid arthritis.

Effect of interferon-gamma, interleukin-2 and interleukin-4 on cyclosporin-A-mediated inhibition of anti-CD3-induced T-lymphocyte proliferation

It is generally believed that cyclosporin A (CsA) inhibits T-cell activation largely by blocking interleukin (IL)-2 production, although CsA also inhibits the secretion of other growth-promoting lymphokines. To investigate the importance of downregulated synthesis of IL-4 and interferon (IFN)-gamma, in addition to IL-2, in CsA-mediated inhibition of T-lymphocyte proliferation, exogenous IL-2, IL-4, and IFN-gamma were added to murine T-cells stimulated with anti-CD3 monoclonal antibody in the presence of an inhibitory concentration of CsA. Either IL-2 or IL-4 alone were able to partially counteract the inhibitory effect of CsA on anti-CD3-induced T-lymphocyte proliferation, whereas IFN-gamma had no discernable effect. IL-2 and IL-4, in combination, were able to largely reverse the immunosuppressive activity of CsA. These results indicate that (1) CsA fails to block T-cell signal transduction pathways coupled to IL-2 and IL-4 receptors, and (2) IL-2 and IL-4 have an additive effect in promoting the proliferation of a heterogenous T-cell population stimulated with anti-CD3 monoclonal antibody.

Blood lymphocytes of autoimmune disease patients receiving FK506 exhibit normal ex vivo cytokine gene expression and proliferative responses

It is well recognized that FK506 (Tacrolimus) is a powerful inhibitor of CD4+ T-cell activation and proliferation in vitro. In this study, immunophenotypic and functional analyses were performed on peripheral blood mononuclear cells from a total of 30 patients with various autoimmune disorders before and whilst the patients were receiving systemic FK506 therapy. The expression of cell surface IL-2R alpha and -beta on CD4+ and CD8+ cells, cytokine message (IL-2, IFN-gamma, IL-4, IL-10) and the proliferative activity of lymphocytes in response to rIL-2 were examined. Despite plasma levels of FK506 compatible with the blockade of IL-2 production by stimulated T cells in vitro, cells from patients on FK506 treatment cultured ex vivo with either ConA or IL-2 did not differ from normal cells in their expression of cytokine mRNA or their proliferative responses. These data indicate that the presumed in vivo suppression of T-cell function by FK506 is rapidly reversible ex vivo. Alternatively/additionally, they suggest that FK506 may mediate its in vivo action primarily by mechanisms other than blockade of T-cell function.

Cytokine gene expression in peripheral blood mononuclear cells during graft-versus-host disease after allogeneic bone marrow transplantation

Cytokine gene expression in peripheral blood mononuclear cells during the development of graft-versus-host disease (GVHD) in patients who underwent allogeneic bone marrow transplantation (allo BMT) was analysed using a semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR). The expression of interleukin (IL)-1 beta, IL-6, and tumour necrosis factor (TNF)-alpha mRNA was increased during the development of GVHD and the degree of this increment depended on the severity of the disease. IL-2 expression was not detected at all and interferon-gamma expression was not much changed during GVHD. In patients with hepatic veno-occlusive disease (VOD), another transplantation-related complication, the expression of IL-1 beta and TNF-alpha mRNA was increased but IL-6 mRNA expression showed little increase. These findings suggest that IL-1 beta, IL-6 and TNF-alpha produced by peripheral blood mononuclear cells play an important role in the development of GVHD. Furthermore, liver dysfunction due to GVHD or VOD may be distinguishable by this type of cytokine analysis. Analysis of cytokine mRNA expression in peripheral blood mononuclear cells after allogeneic bone marrow transplantation may provide important information concerning the immune response and the cytokine network system in marrow transplant patients.

Demonstration of large-scale migration of cortical thymocytes to peripheral lymphoid tissues in cyclosporin A-treated rats

Young adult Lewis rats were maintained on diets containing 0.015 or 0.027% cyclosporin A (CSA) for periods of up to 6 wk. All animals showed complete depletion of medullary thymocytes (CD4+8- and CD4-8+, T cell receptor [TCR] alpha/beta hi, Thy-1med/low, terminal deoxynucleotidyl transferase negative [TdT-]) and a 50% reduction in the number of TdT- cortical thymocytes (CD4+8+, TCR alpha/beta low, Thy-1med) within 1 wk of CSA treatment. In addition, about half of the animals displayed a 50% reduction in the number of TdT+ cortical thymocytes (CD4+8+, TCR alpha/beta low, Thy-1hi). These intrathymic changes were accompanied by a reciprocal increase in the number of double-positive (DP; CD4+8+) T cells in lymph nodes (LN) and spleens. To confirm that the latter T cells were recent thymic emigrants (RTE), CSA-treated rats were injected intrathymically with fluorescein isothiocyanate, and the phenotype of the labeled T cells appearing in LN was determined 16 h later. The results demonstrated that, in addition to those RTE exported in normal animals (> 90% medullary origin), the emigration of DP thymocytes, including large numbers of TdT+ thymocytes, was markedly increased. The presence of TdT+ cells, which normally do not leave the thymus, clearly identifies the DP RTE as originating from the thymus cortex. Intrathymic labeling studies also directly demonstrated that export of all thymocyte subsets ceases within 9 d of CSA treatment; and thymectomy experiments confirmed that the CSA-induced increase in phenotypically immature T cells resulted primarily from the disturbance of thymocyte maturation and emigration, rather than from a direct effect on preexisting T cells. These results suggest that a wave of cortical thymocytes, many of which presumably have not yet undergone negative selection, is released from the thymus during the first week of CSA treatment. The presence of these potentially unselected cells in peripheral lymphoid tissues may help to explain the increased frequency of autoreactive T cells observed in CSA-treated animals.

Accelerated atherosclerosis in hyperlipidemic C57BL/6 mice treated with cyclosporin A

We and others have demonstrated that T lymphocytes are prominent components of atherosclerotic lesions. We hypothesized that if T cells were necessary for the development of atherosclerosis it would be possible to demonstrate its prevention or retardation in T-cell-suppressed mice. To test this hypothesis, CyA, a potent suppressor of T-cell activation, was used to treat C57BL/6 mice undergoing lipid hyperalimentation. Mice receiving normal mouse chow were completely free of atherosclerotic lesions. In mice receiving the atherogenic diet plus control oil injections, lesions of the aorta and coronary arteries were observed at 135 days and increased progressively in area until 310 days. Somewhat surprisingly, mice given the atherogenic diet plus CyA injections displayed even larger lesions at all three observed time intervals. Although CyA did suppress T-cell reactivity sufficiently to obtain the expected prolongation of skin allografts, it did not suppress the development or progression of atherosclerotic lesions.

Cyclosporin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in immunoregulatory disorders

Cyclosporin is a lipophilic cyclic polypeptide which produces calcium-dependent, specific, reversible inhibition of transcription of interleukin-2 and several other cytokines, most notably in T helper lymphocytes. This reduces the production of a range of cytokines, inhibiting the activation and/or maturation of various cell types, including those involved in cell-mediated immunity. Thus, cyclosporin has immunosuppressive properties, and has a proven place as first line therapy in the prophylaxis and treatment of transplant rejection. Cyclosporin has also been evaluated in a large range of disorders where immunoregulatory dysfunction is a suspected or proven aetiological factor, and this is the focus of the present review. In patients with severe disease refractory to standard treatment, oral cyclosporin is an effective therapy in acute ocular Behçet's syndrome, endogenous uveitis, psoriasis, atopic dermatitis, rheumatoid arthritis, active Crohn's disease and nephrotic syndrome. Concomitant low dose corticosteroid therapy may improve response rates in some disorders. The drug can be considered as a first line therapy in patients with moderate or severe aplastic anaemia who are ineligible for bone marrow transplantation, with the additional benefit of reducing platelet alloantibody titres. It may also be of considerable therapeutic benefit in patients with primary biliary cirrhosis, particularly those with less advanced disease. Limited evidence suggests cyclosporin is effective in patients with intractable pyoderma gangrenosum, polymyositis/dermatomyositis or severe, corticosteroid-dependent asthma. Indeed, the steroid-sparing effect of cyclosporin is a significant advantage in a number of indications. Furthermore, the drug has shown some efficacy in a wide range of other, generally uncommon disorders in which controlled clinical trials are lacking and/or are unlikely to be performed. Cyclosporin does not appear to be effective in patients with allergic contact dermatitis, multiple sclerosis or amyotrophic lateral sclerosis. It is only temporarily effective in patients with type I (insulin-dependent) diabetes mellitus and should not be used in this indication. To avoid relapse after control of active disease, patients should receive cyclosporin maintenance therapy at the lowest effective dosage. However, maintenance therapy appears to be of no benefit in patients with Crohn's disease and cyclosporin should be discontinued in these patients once active disease is controlled. Hypertrichosis, gingival hyperplasia, and neurological and gastrointestinal effects are the most common adverse events in cyclosporin recipients, but are usually mild to moderate and resolve on dosage reduction. Changes in laboratory variables indicating renal dysfunction are relatively common, although serious irreversible damage is rare.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-CD3-induced T-cell activation--II. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

An in vivo model was used to examine the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on various parameters of T-cell-activation. In this model, the hamster anti-mouse monoclonal antibody 145-2C11 (anti-CD3) to the CD3 portion of the murine T-cell receptor was injected into both rear footpads of female C57B1/6 mice and the draining popliteal and inguinal lymph node cells (LNC) were removed 24 h later. Cyclosporin A (CsA) was included as a known immunosuppressive control. As expected, CsA (50 mg/kg, i.p.) suppressed anti-CD3-induced proliferation, IL-2-driven 3H-TdR incorporation, and IL-2R expression. In contrast, TCDD unexpectedly enhanced anti-CD3-induced 3H-TdR incorporation. Flow cytometric analysis showed that TCDD treatment increased the percentage of both CD4+ and CD8+ cells cycling in S and G2M. LNC from TCDD-treated mice also had enhanced 3H-TdR incorporation when cultured in the presence of a saturating amount of exogenous mIL-2. TCDD did not significantly alter the percent positive or the number of IL-2 receptors (IL-2R) on either CD4+ or CD8+ cells when examined at several time points after anti-CD3 treatment. Both the kinetics and extent of anti-CD3-induced down-modulation of CD3 expression on CD4+ and CD8+ cells was unaffected by TCDD. TCDD alone did not result in enhanced 3H-TdR incorporation, cell cycling or IL-2R expression. Therefore, TCDD appears to be targeting T-cells that are undergoing activation rather than resting cells. The strength of the anti-CD3 model is evidenced by the fact that two known immunosuppressive compounds (CsA and TCDD) have distinct and opposite effects on T-cell activation. These findings suggest that the mechanism(s) by which CsA and TCDD impair T-cell function are different.

In vivo induction of interleukin 10 by anti-CD3 monoclonal antibody or bacterial lipopolysaccharide: differential modulation by cyclosporin A

We investigated the in vivo effects of cyclosporin A (CsA) on the production of interleukin (IL) 10, a cytokine with major immunosuppressive properties. To elicit IL-10 production in vivo, BALB/c mice were injected either with the anti-mouse CD3 145-2C11 monoclonal antibody (mAb) (25 micrograms) or with bacterial lipopolysaccharide (LPS) (20 micrograms). A systemic release of IL-10 was observed in both models, IL-10 serum levels reaching 1.60 +/- 0.32 U/ml (mean +/- SEM) and 0.67 +/- 0.09 U/ml 6 h after injection of 145-2C11 mAb and LPS, respectively. Experiments in nude mice indicated that T cells are involved in the induction of IL-10 by anti-CD3 mAb, but not by LPS. Pretreatment with CsA (total dose: 50 mg/kg) before injection of 145-2C11 mAb completely prevented the release of IL-10 in serum as well as IL-10 mRNA accumulation in spleen cells. In contrast, CsA markedly enhanced LPS-induced IL-10 release (IL-10 serum levels at 6 h: 8.31 +/- 0.43 vs. 0.71 +/- 0.15 U/ml in mice pretreated with CsA vehicle-control, p < 0.001), as well as IL-10 mRNA accumulation in spleen. We conclude that CsA differentially affects IL-10 production in vivo depending on the nature of the eliciting agent. This observation might be relevant to clinical settings, especially in organ transplantation.

The mechanisms of action of cyclosporin A in the treatment of psoriasis

This article describes the effects of cyclosporin A (CsA) on the immunopathological mechanisms operative in psoriasis, a human skin disease. The main focus is the effect of CsA on keratinocytes, T cells and antigen-presenting cells, the key players in lesional psoriatic skin. The effect of CsA on other cells, such as neutrophils and endothelial cells, which are important in the maintenance of psoriasis, are also discussed.

Characterization of the inhibition of renal translation in the Sprague-Dawley rat following in vivo cyclosporin A

"Run-off" translation assays in microsomes isolated from Sprague-Dawley rats were used to examine the capacity of cyclosporin A (CsA) to alter translation elongation. CsA added in vitro in concentrations of up to 100 micrograms/ml did not reduce "run-off" translation measured as 3H-L-leucine incorporation in microsomes isolated from the rat kidney or thymus. In contrast, the oral administration of CsA at 50 mg/kg/day for 6 days resulted in reductions in 3H-L-leucine incorporation by microsomes isolated from rat kidneys and unstimulated thymus to 21.6 and 83.0% of control values, respectively. In cross-over experiments between renal microsomal and cytoplasmic fractions, 3H-L-leucine incorporation was inhibited following the addition of renal cytoplasm from CsA treated rats to renal microsomal fractions from control vehicle treated rats. Translation inhibition was still observed when renal cytoplasm from CsA treated rats was added along with renal cytoplasm from control rats to renal microsomes isolated from rats treated with control vehicle. Reductions in renal 3H-L-leucine incorporation were not due to a stimulation of renal protease activity. Experiments varying the concentration of individual components of the microsomal translation assays suggested that renal microsomes from CsA treated animals were saturated with substrate or cofactor at lower concentrations than control microsomes. Time course experiments showed a marked reduction in the duration and extent of 3H-L-leucine incorporation by renal microsomes from CsA treated animals compared to controls. Sucrose density gradient analysis of microsomes from CsA treated animals confirmed that elongation was inhibited. These findings suggest that the in vivo administration of CsA results in the formation of a direct-acting inhibitor of renal translation rather than reducing translation by producing changes in renal transcription. The observation that renal translation is inhibited only after in vivo CsA suggests that a CsA metabolite formed in, or taken up by, the kidney produces translation inhibition, or that a cellular product involved in translation or translation regulation is formed or induced. We propose that the CsA induced inhibition of renal translation elongation accounts, at least in part, for CsA-induced nephrotoxicity.

Anti-CD3-induced T-cell activation in vivo--I. Flow cytometric analysis of dose-responsive, time-dependent, and cyclosporin A-sensitive parameters of CD4+ and CD8+ cells from the draining lymph nodes of C57Bl/6 mice

An in vivo model to assess the effects of chemicals on T-cell activation has been characterized and validated using the immunosuppressive drug, cyclosporin A (CsA). The dose response and kinetic effects of the hamster anti-mouse monoclonal antibody 145-2C11 (anti-CD3) on various parameters of T-cell activation were examined in cells from the draining popliteal and inguinal lymph nodes of C57Bl/6 mice. Parameters of anti-CD3-induced T-cell activation included 3H-TdR incorporation (+/- recombinant murine IL-2), and flow cytometric analysis of CD3 and IL-2 receptor (IL-2R) expression on CD4+ and CD8+ cells. Increases in the percentage of lymphocyte subsets in the S/G2M phase of the cell cycle and total cell recovery following anti-CD3 are also reported. Increased 3H-TdR incorporation was maximal over a dose range of 0.25-25 micrograms anti-CD3, while maximal increases in the percentage of CD4+ and CD8+ cycling occurred after a dose of 2.5 micrograms anti-CD3. At 24 h after anti-CD3 treatment, CD3 expression on both CD4+ and CD8+ cells was dose dependently down-modulated while IL-2R expression and IL-2-driven 3H-TdR incorporation were dose dependently increased. In addition, total cell recovery increased at 24 h and correlated with an increase in the percentage of B220+ cells present in the lymph nodes. There was a corresponding decrease in the percentage of Thy 1.2+, CD4+, and CD8+ cells. No increase in cycling of B220+ cells was observed, suggesting an influx of B220+ cells into the node rather than proliferation. Elevation in 3H-TdR incorporation occurred as early as 4 h after anti-CD3 treatment, while increases in the percentage of CD4+ and CD8+ cells cycling were not apparent until 24 h. At 48 h, the percentage of CD8+ cells cycling doubled while the percentage of CD4+ cells cycling remained constant. Down-modulation of CD3 expression on CD4+ and CD8+ cells was apparent as early as 1 h after treatment with less than 10% of CD4+ and CD8+ cells expressing CD3 by 12 h. Induction of IL-2R expression and IL-2-driven 3H-TdR incorporation was maximal at 12 h after anti-CD3. The immunosuppressive drug, CsA (25, 50, or 100 mg/kg, i.p.) decreased anti-CD3-induced 3H-TdR incorporation. Concurrently, anti-CD3-induced increases in the percentage of CD4+ and CD8+ cells cycling were inhibited by CsA. Likewise, IL-2 responsiveness and IL-2R expression on both T-cell subsets were inhibited by CsA.(ABSTRACT TRUNCATED AT 400 WORDS)

Soluble interleukin 2 receptor (Tac chain) is not a reliable marker in kidney transplant recipient monitoring

T lymphocyte expansion is triggered through interaction of interleukin 2 (IL-2) with its high-affinity receptor (IL-2R). This molecule is a heterodimer comprising an antigen-inducible component, the Tac chain (P55). Activation of T lymphocytes also generates a soluble form of this P55 called S-IL-2R. S-IL-2R is elevated in many T-cell-related pathologies (leukemia, autoimmunity, etc.). In graft recipients, rejection is a result of T-cell activation by graft antigens and therefore might induce a release of S-IL-2R in the circulation; this parameter is now said to be a good indicator of rejection. We have performed a study in renal graft recipients in order to assess the usefulness of circulating S-IL-2R particularly to discriminate the origin of renal failure in cases of rejection or of cyclosporin-A (CsA)-induced nephrotoxicity. We demonstrated that there are no differences between isolated values in the clinical groups at the time of diagnosis. Variations in S-IL-2R are increased compared to steady-state periods during rejection and cytomegalovirus infections, although not in CsA toxicity episodes. However, at the individual level there are too many false-positive and false-negative results, making this parameter no more meaningful than serum creatinine levels alone or even in association (as tested in logistic discriminant analysis). In addition, it seems that the variations in S-IL-2R are partly related to renal function itself, as suggested by the correlation between S-IL-2R levels and serum creatinine levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of action of cyclosporine and effects on connective tissues

Cyclosporine is a potent immunomodulatory agent with an increasing number of clinical applications. Its major mode of action is inhibition of the production of cytokines involved in the regulation of T-cell activation. In particular, cyclosporine inhibits the transcription of interleukin 2. Although cyclosporine's major actions are on T cells, there is some evidence that it produces direct effects on other cell types. Its immunosuppressive action is closely linked to its binding of cyclophilin, a member of a family of high-affinity cyclosporine-binding proteins widely distributed in different cell types and in different species. The cyclophilins have been shown to have peptidyl-prolyl cis-trans isomerase enzyme activity that is blocked by cyclosporine. Although this may be a factor in cyclosporine's selective inhibition of cytokine gene transcription, it is still unclear whether inhibition of this activity is the mechanism through which cyclosporine exerts its effects on target cells. The ubiquitous presence of cyclophilins raises the question of why cyclosporine has major effects on T cells. Perhaps the critical proteins affected are transcriptional regulators restricted in their tissue distribution. The effects of cyclosporine on T cells and, directly or indirectly, on connective tissue cells, all of which can produce a range of cytokines, are of interest in relation to the tissue changes that occur in such inflammatory conditions as rheumatoid arthritis.

Effects of changes in membrane potential on the cyclosporin-induced inhibition of T-cell proliferation

Cyclosporin A (CsA) exerts its major immunosuppressive effect by inhibition of T-lymphocyte proliferation. The precise mechanism and target of its action has not yet been completely identified. CsA is also known to induce a rapid membrane depolarization in T lymphocytes. We have tested the role of CsA-dependent depolarization in the inhibition of T-cell proliferation by the drug. In these studies, induced membrane depolarization (in the presence of gramicidin or by replacing the Na+ content of the medium with K+) or hyperpolarization (in the presence of valinomycin) had no influence on the induction of T-cell competence by phorbol dibutyrate/ionomycin or by submitogenic concentrations of PHA, a target for CsA immunosuppression. However, regardless of the state of membrane potential during the induction of T-cell competence, the inhibition by CsA was the same as seen in normally polarized cells. We conclude that the depolarization induced by CsA is not a critical element in its inhibitory effect on T-cell proliferation.

Molecular mode of action of cyclosporin and FK506 in human thymocytes

The molecular mode of action of cyclosporin, three of its non-immunosuppressive analogs, N-methyl-l-alanyl cyclosporin, acetyl cyclosporin and cyclosporin S3, and of FK506 was studied in primary cultures of human thymocytes. Nuclear factors derived from thymocytes activated with phorbol myristate acetate and concanavalin A were tested for their ability to bind to a synthetic radiolabelled probe corresponding to the NF-AT region (-285 to -255) of the IL-2 gene. Binding was observed, and it was inhibited by CsA (100 ng/ml), while the analogs at ten-fold higher concentrations (1000 ng/ml) were only partially inhibitory. CsA in combination with FK506 inhibited binding of nuclear factors at the NF-AT site, and acted in concert.

Expansion and clonal deletion of peripheral T cells induced by bacterial superantigen is independent of the interleukin-2 pathway

Injection of the bacterial superantigen Staphylococcus aureus enterotoxin B (SEB) into mice provokes a rapid expansion and subsequent contraction of the pool of SEB-reactive T cells bearing T cell receptor (TcR) V beta 8 gene products. Given that interleukin 2 (IL-2) stimulates proliferation, abolishes anergy, and counteracts apoptotic cell death in T cells in vitro, we tested whether the IL-2 synthesis inhibitor cyclosporin A (CsA) or a vaccinia virus recombinant releasing high amounts of human IL-2 modulate SEB responses in vivo. Surprisingly, neither IL-2 nor CsA were able to change the in vivo kinetics and magnitude of SEB-induced expansion, unresponsiveness to SEB, and peripheral clonal deletion of T cells expressing products of the SEB-reactive TcR V beta 8 gene family. In accord with these in vivo observations, IL-2 is incapable of reversing "anergy" and apoptotic cell death of V beta 8+ SEB-reactive T cells isolated from SEB-primed mice in vitro. Accordingly, upon SEB injection V beta 8+ T cells expand rapidly, without expressing IL-2 receptor (IL-2R)alpha chains in vivo, although SEB induces IL-2R alpha in vitro. Altogether, these results indicate that the IL-2/IL-2R-mediated pathway is not involved in T cell repertoire modulation by bacterial superantigens. Moreover, the data suggest that unresponsiveness of V beta 8+ T cells from SEB-primed mice is not a reversible process, but involves an unreversible commitment to programmed cell death. Absence or presence of IL-2 responsiveness could be a hallmark to distinguish truly reversible anergy and peripheral clonal deletion.

The mechanism of action of cyclosporin A and FK506

CsA and FK506 are powerful suppressors of the immune system, most notably of T cells. They act at a point in activation that lies between receptor ligation and the transcription of early genes. Here, Stuart Schreiber and Gerald Crabtree review recent findings that indicate CsA and FK506 operate as prodrugs: they bind endogenous intracellular receptors, the immunophilins, and the resulting complex targets the protein phosphatase, calcineurin, to exert the immunosuppressive effect.

Studies of the Effect of Cyclosporine in Psoriasis In Vivo: Combined Effects on Activated T Lymphocytes and Epidermal Regenerative Maturation

Cyclosporine (CSA) decreases lymphokine synthesis and keratinocyte proliferation in vitro, but its in vivo mechanism of action in treating recalcitrant psoriasis is incompletely understood. Ten psoriasis patients were treated with CSA (2-7.5 mg/kg/d) with clinical improvement in nine of 10 patients. Skin biopsies before and after 1-3 months of CSA treatment were studied for evidence of immune and keratinocyte activation using immunoperoxidase and Northern blotting analysis. The number of activated, IL-2 receptor+ T cells in plaques after CSA treatment was reduced in all patients by a mean of 60%. Seven of 10 patients showed a decrease in keratinocyte HLA-DR expression; five of seven showed a decrease in gamma-IP-10 immunoreactivity, suggesting a decline in gamma interferon levels in plaques after CSA therapy. We studied the effect of CSA treatment in vivo on TGF-alpha, IL-6, and keratin K16 expression, three markers of keratinocyte growth activation. Expression of keratinocyte TGF-alpha and IL-6, which are elevated in active psoriatic epidermis, did not change in these patients after CSA treatment. The majority of patients (five of eight) continued to express the hyperproliferative keratin K16 after CSA treatment. Our results suggest that the predominant direct mechanism of action of Cyclosporine in vivo is a diminution of T-cell activation in plaques, with attendant decreased lymphokine production.