Altered tumor growth factor beta mRNA expression is associated with thymectomy-related clinical remission in myasthenia gravis

Clinical efficacy of tacrolimus for treating myasthenia gravis and its influence on lymphocyte subsets

BACKGROUND

This study aimed to determine the clinical efficacy and effects of tacrolimus in treating myasthenia gravis (MG).

METHODS

A total of 45 outpatients and inpatients were divided into a tacrolimus group (n=15) and non-tacrolimus group (n=30): those in the former group were treated with 3mg/day of tacrolimus for 24 weeks, while those in the latter (control) group took other immunosuppressants (prednisone, azathioprine combined with prednisone). Each group was evaluated at weeks 4, 8, 12, 16, 20 and 24 by Myasthenia Gravis Foundation of America Quantitative Myasthenia Gravis (MGFA-QMG) Test, activities of daily living (ADL) profiles, and manual muscle (MMT) and fatigue tests. Dynamic changes in CD4⁺CD25^+high cells were tested by flow cytometry. Inflammatory cytokines were also evaluated in the tacrolimus group.

RESULTS

Efficacy index scores decreased significantly compared with baseline at every test week in both groups (P<0.01), although improvements were more evident with than without tacrolimus treatment (F=9.312, P<0.01 vs. F=24.551, P<0.01 and F=10.710, P<0.01). At week 24, peripheral blood CD4⁺CD25^+high T cells with tacrolimus decreased significantly (P<0.01), but increased significantly without tacrolimus (P<0.01). During treatment, CD19⁺BAFF-R B cells in peripheral blood decreased in both groups (P<0.05). Interferon (IFN)-γ concentrations in peripheral blood also diminished significantly with tacrolimus (P<0.01).

CONCLUSION

A relatively low dose of tacrolimus can affect multiple immune-system targets and, thus, can treat MG effectively in terms of both clinical symptoms and immunological responses.

microRNA-145 Mediates the Inhibitory Effect of Adipose Tissue-Derived Stromal Cells on Prostate Cancer

Adipose-derived stromal cell (ASC), known as one of the mesenchymal stem cells (MSCs), is a promising tool for regenerative medicine; however, the effect of ASCs on tumor growth has not been studied sufficiently. We investigated the hypothesis that ASCs have an inhibitory effect on metastatic tumor progression. To evaluate the in vitro inhibitory effect of ASCs on metastatic prostate cancer (PCa), direct coculture and indirect separate culture experiments with PC3M-luc2 cells and human ASCs were performed, and ASCs were administered to PC3M-luc2 cell-derived tumor-bearing nude mice for in vivo experiment. We also performed exosome microRNA (miRNA) array analysis to explore a mechanistic insight into the effect of ASCs on PCa cell proliferation/apoptosis. Both in vitro and in vivo experiments exhibited the inhibitory effect of ASCs on PC3M-luc2 cell proliferation, inducing apoptosis and PCa growth, respectively. Among upregulated miRNAs in ASCs compared with fibroblasts, we focused on miR-145, which was known as a tumor suppressor. ASC-derived conditioned medium (CM) significantly inhibited PC3M-luc2 cell proliferation, inducing apoptosis, but the effect was canceled by miR-145 knockdown in ASCs. ASC miR-145 knockdown CM also reduced the expression of Caspase 3/7 with increased antiapoptotic protein, BclxL, expression in PC3M-luc2 cells. This study provides preclinical data that ASCs inhibit PCa growth, inducing PCa cell apoptosis with reduced activity of BclxL, at least in part, by miR-145, including exosomes released from ASCs, suggesting that ASC administration could be a novel and promising therapeutic strategy in patients with PCa.

Adipose-derived stromal cells inhibit prostate cancer cell proliferation inducing apoptosis

Mesenchymal stem cells (MSCs) have generated a great deal of interest in the field of regenerative medicine. Adipose-derived stromal cells (AdSCs) are known to exhibit extensive proliferation potential and can undergo multilineage differentiation, sharing similar characteristics to bone marrow-derived MSCs. However, as the effect of AdSCs on tumor growth has not been studied sufficiently, we assessed the degree to which AdSCs affect the proliferation of prostate cancer (PCa) cell. Human AdSCs exerted an inhibitory effect on the proliferation of androgen-responsive (LNCaP) and androgen-nonresponsive (PC3) human PCa cells, while normal human dermal fibroblasts (NHDFs) did not, and in fact promoted PCa cell proliferation to a degree. Moreover, AdSCs induced apoptosis of LNCaP cells and PC3 cells, activating the caspase3/7 signaling pathway. cDNA microarray analysis suggested that AdSC-induced apoptosis in both LNCaP and PC3 cells was related to the TGF-β signaling pathway. Consistent with our in vitro observations, local transplantation of AdSCs delayed the growth of tumors derived from both LNCaP- and PC3-xenografts in immunodeficient mice. This is the first preclinical study to have directly demonstrated that AdSC-induced PCa cell apoptosis may occur via the TGF-β signaling pathway, irrespective of androgen-responsiveness. Since autologous AdSCs can be easily isolated from adipose tissue without any ethical concerns, we suggest that therapy with these cells could be a novel approach for patients with PCa.

Immunomodulation by a dual altered peptide ligand of autoreactive responses to the acetylcholine receptor of peripheral blood lymphocytes of patients with myasthenia gravis

Myasthenia gravis (MG) is a T cell-dependent, antibody-mediated autoimmune disease. A dual altered peptide ligand (APL) that is composed of the tandemly arranged two single amino acid analogs of two myasthenogenic peptides was demonstrated to downregulate in vitro and in vivo murine MG associated autoreactive responses. Furthermore, treatment with the dual APL ameliorated the clinical manifestations of an established experimental autoimmune MG in mice. This study was undertaken in order to investigate the ability of the dual APL to immunomodulate MG-associated responses of peripheral blood lymphocytes (PBL) of patients with MG to the native autoantigen acetylcholine receptor (AChR). PBL of 22 of 27 patients with MG tested responded by proliferation to torpedo AChR. The proliferative responses of PBL of 21 of 22 responders were significantly inhibited by the dual APL. The inhibition was specific because a control peptide did not inhibit these proliferative responses. The dual APL also downregulated the levels of the secreted pathogenic cytokine IFN-gamma in supernatants of stimulated PBL of 80% of the tested patients. The latter inhibitions correlated with an upregulated production of the immunosuppressive cytokine, tumor growth factor beta. Thus, the results of our study demonstrate that the dual APL is capable of downregulating in vitro autoreactive responses of patients with MG and suggest that this peptide is a potential candidate for a novel specific treatment of patients with MG.

Therapeutic vaccines in autoimmunity

Similarly to prophylactic vaccines whose purpose is to prevent infectious diseases, therapeutic vaccines against autoimmune diseases are based on their similarity to the putative causes of the disease. We shall describe here two such examples: a copolymer of amino acids related to myelin basic protein, in the case of multiple sclerosis, and a peptide derived from the nicotinic acetylcholine receptor (AChR), in the case of myasthenia gravis (MG). Copolymer 1 (Cop 1, glatiramer acetate, Copaxone) is a synthetic amino acid random copolymer, immunologically cross-reactive with myelin basic protein and suppresses experimental allergic encephalomyelitis in several animal species. Cop 1 slows the progression of disability and reduces relapse rate in exacerbating-remitting multiple sclerosis patients. It was approved by the Food and Drug Administration in 1996, and today is used by tens of thousands of patients. Cop 1 is a potent inducer of T helper 2 (Th2) regulatory cells in mice and humans, and Th2 cells are found both in the brains and spinal cords of Cop 1-treated mice. MG and experimental autoimmune MG are T cell-regulated, antibody-mediated autoimmune diseases. Two peptides, representing sequences of the human AChR alpha-subunit, p195-212 and p259-271, are immunodominant T cell epitopes in MG patients and in two strains of mice. Altered peptide ligand, composed of the tandemly arranged two single amino acid analogs, inhibits in vitro and in vivo MG-associated autoimmune responses. The active suppression is mediated by the CD4(+)CD25(+) immunoregulatory cells and is associated with the down-regulation of Th1-type cytokines and the up-regulation of the secretion of IL-10 and the immunosuppressive cytokine, transforming growth factor beta.

Dehydroepiandrosterone therapy ameliorates experimental autoimmune myasthenia gravis in Lewis rats

To detect a possible effect of dehydroepiandrosterone (DHEA) in the pathogenesis of experimental autoimmune myasthenia gravis (EAMG), DHEA (0.5 mg/rat) was administrated intraperitoneally to Lewis rats every other day from day 4 postimmunization (p.i.) to day 35 p.i. with Torpedo acetylcholine receptor (AChR) and Freund's complete adjuvant. Rats treated with DHEA had a lower clinical score (mean clinic score, 2 versus 0.5 on day 37 p.i.) and a lower body weight loss (mean body weight, 169 versus 142 g on day 37 p.i.) compared with control EAMG rats. DHEA treatment decreased serum anti-AChR IgG and IgG2b antibody titers on days 7, 14, and 21 p.i. and inhibited the levels of anti-AChR IgG antibody secreting cells (60%), accompanied by decreased IL-4 (33%) and augmented TGF-beta1-positive cells (41%) among lymph node mononuclear cells. These results obtained from EAMG in Lewis rats further encourage us to study DHEA treatment in human MG.

Anti-TNF-alpha antibodies suppress the development of experimental autoimmune myasthenia gravis

To understand the role of TNF-alpha in the induction of experimental autoimmune myasthenia gravis (EAMG) and detect a possible effect of anti-TNF-alpha antibodies in the treatment of EAMG, anti-TNF-alpha antibodies were administrated intraperitoneally to Lewis rats twice per week for 5 weeks from the day of immunization with Torpedo AChR and complete Freund's adjuvant (CFA). Administration of anti-TNF-alpha antibodies resulted in lower incidence of EAMG, and in delayed onset and only mild muscle weakness compared with control EAMG rats. These mild clinical signs were accompanied by lower AChR-specific lymphocyte proliferation, down-regulated IFN-gamma and IL-10, and up-regulated TGF-beta. The lower levels of anti-AChR IgG, Ig2a and IgG2b and decreased anti-AChR IgG affinity were found in rats treated with anti-TNF-alpha antibodies. These results demonstrate that anti-TNF-alpha antibodies can suppress the induction and development of EAMG.

The nature of the active suppression of responses associated with experimental autoimmune myasthenia gravis by a dual altered peptide ligand administered by different routes

Myasthenia gravis (MG) and experimental autoimmune MG (EAMG) are T-cell regulated, antibody-mediated diseases. Peptides p195-212 and p259-271 of the human acetylcholine receptor (AChR) alpha-subunit, were previously shown to be immunodominant T cell epitopes in MG patients as well as in SJL and BALB/c mice, respectively. A dual altered peptide ligand (APL) composed of the two single amino acid analogs of the myasthenogenic peptides was shown to inhibit, in vitro and in vivo, MG-associated autoimmune responses. Furthermore, the dual APL was shown to down-regulate the clinical manifestations of an established EAMG in C57BL/6 mice injected with Torpedo AChR (TAChR). In the present study we attempted the elucidation of the mechanism(s) by which the dual APL down-regulates EAMG-associated responses. It is shown here that the dual APL acts by actively suppressing, in a specific manner, myasthenogenic T cell responses. The active suppression is mediated, at least partially, by the up-regulation of the secretion of TGF-beta following administration of the dual APL. The up-regulated secretion of TGF-beta is accompanied by down-regulation of IFN-gamma and IL-2 [T helper (Th) 1-type cytokine] secretion and by an up-regulation of IL-10 secretion (Th2-type cytokine). Furthermore, the inhibitory effect of the dual APL could be adoptively transferred to p195-212 or TAChR-immunized mice. The down-regulation of IL-2 secretion and the ability of recombinant IL-2 to rescue lymph node cells of mice treated with the dual APL from a state of unresponsiveness suggests that the dual APL acts also, at least partially, by causing the cells to undergo anergy.