In vitro and in vivo transfection of p21 gene enhances cyclosporin A-mediated inhibition of lymphocyte proliferation

Eucommia ulmoides Oliv. (Du-Zhong) Lignans Inhibit Angiotensin II-Stimulated Proliferation by Affecting P21, P27, and Bax Expression in Rat Mesangial Cells

Cortex Eucommiae (Du-zhong) is the dried bark of the Eucommia ulmoides Oliv. The natural products identified from Du-zhong include lignans, iridoids, flavonoids, polysaccharides, terpenes, and proteins, Liu et al. (2012). Lignans, the main bioactive components, were protective against hypertensive renal injury in spontaneous hypertensive rats in our previous study, Li et al. (2012). Moreover, Eucommia lignans also diminished aldose reductase (AR) overexpression in the kidney, Li et al. (2012). However, the pathological mechanism underlying the protective effects of Eucommia lignans remains unknown. Cellular proliferation was reported to contribute to important pathological changes in hypertensive renal injuries, and increased angiotensin II (Ang II) expression was reported to be essential for target-organ damage during hypertension. Ang II is the main effective peptide in the renin-angiotensin system and is considered to be a key mediator in the development of hypertensive nephropathy, Rüster and Wolf (2011). Our preliminary results showed that Eucommia lignans had inhibitory effects on Ang II-induced proliferation of rat mesangial cells. In the present study, we investigated the effects of Eucommia ulmoides on Ang II-induced proliferation and apoptosis of rat mesangial cells. Cell cycle-related genes P21 and P27, and cell apoptosis-related genes Bax and Bcl-2, were determined.

Enhanced susceptibility of cyclin kinase inhibitor p21 knockout mice to high fat diet induced atherosclerosis

Cyclin kinase inhibitor p21 is one of the most potent inhibitors of aortic smooth muscle cell proliferation, a key mediator of atherosclerosis. This study tests if p2l deficiency will result in severe atherosclerosis in a mouse model. p21-/- and strain matched wild type mice were fed with high fat diet for 21 weeks. Analysis for biochemical parameters (cholesterol, triglycerides) in serum and mRNA expression of CD36, HO-1, TGF-beta, IFN-gamma, TNF-alpha, PPAR-gamma and NADPH oxidase components (p22phox, NOX-1 and Rac-1) was performed in aortic tissues by Real Time PCR. p21-/- mice gained significantly (p < 0.01) more weight than wild type mice, triglycerides (p < 0.05) and cholesterol levels (p < 0.01) were more pronounced in the sera of p21-/- compared to wild type mice fed with high fat diet. High fat diet resulted in significantly decreased TGF-beta (p < 0.02), HO-l (p < 0.02) and increased CD36 (p < 0.03) mRNA expression in aortic tissues of p21-/- mice compared to animal fed with regular diet. IFN-gamma mRNA expression (235 +/- 11 folds) increased significantly in high fat diet fed p21-/- mice and a multifold modulation of PPAR-gamma(136 +/- 7), p22phox, NOX-1 and Rac-1 (15-35-folds) mRNA in aortic tissues from p21-/- mice compared to the wild type mice. Severity of atherosclerotic lesions was significantly higher in p21-/- compared to wild type mice. The results demonstrate that the deficiency of p21 leads to altered expression of pro-atherogenic genes, and severe atherosclerosis in mice fed with high fat diet. This opens the possibility of p21 protein as a therapeutic tool to control progression of atherosclerosis.

p21CIP1/WAF1 Controls Proliferation of Activated/Memory T Cells and Affects Homeostasis and Memory T Cell Responses

Development of autoantibodies and lupus-like autoimmunity by 129/Sv x C57BL/6 p21(-/-) mice has established that cell cycle deregulation is one the defective pathways leading to break of tolerance. Memory T cell accumulation is thought to be related to tolerance loss in murine lupus models. We studied T cell memory responses in C57BL/6 p21(-/-) mice that develop lupus-like disease manifestations. p21 did not affect primary proliferation of naive T cells, and was required for cycling control, but not for apoptosis of activated/memory T cells. When we induced apoptosis by secondary TCR challenge, surviving memory T cells depended on p21 for proliferation control. Under conditions of secondary T cell stimulation that did not cause apoptosis, p21 was also needed for regulation of activated/memory T cell expansion. The requirement for p21 in the control of T cell proliferation of activated/memory T cells suggests that in addition to apoptosis, cycling regulation by p21 constitutes a new pathway for T cell homeostasis. Concurring with this view, we found accumulation in p21(-/-) mice of memory CD4(+) T cells that showed increased proliferative potential after TCR stimulation. Furthermore, OVA immunization of p21(-/-) mice generated hyperresponsive OVA-specific T cells. Overall, the data show that p21 controls the proliferation of only activated/memory T cells, and suggest that p21 forms part of the memory T cell homeostasis mechanism, contributing to maintenance of tolerance.

Targeted in vitro and in vivo gene transfer into T lymphocytes: potential of direct inhibition of allo-immune activation

Background

Successful inhibition of alloimmune activation in organ transplantation remains one of the key events in achieving a long-term graft survival. Since T lymphocytes are largely responsible for alloimmune activation, targeted gene transfer of gene of cyclin kinase inhibitor p21 into T cells might inhibit their aberrant proliferation. A number of strategies using either adenoviral or lentiviral vectors linked to mono or bispecific antibodies directed against T cell surface markers/cytokines did not yield the desired results. Therefore, this study was designed to test if a CD3promoter-p21 chimeric construct would in vitro and in vivo transfer p21 gene to T lymphocytes and result in inhibition of proliferation. CD3 promoter-p21 chimeric constructs were prepared with p21 in the sense and antisense orientation. For in vitro studies EL4-IL-2 thyoma cells were used and for in vivo studies CD3p21 sense and antisense plasmid DNA was injected intramuscularly in mice. Lymphocyte proliferation was quantified by ³H-thymidine uptake assay; IL-2 mRNA expression was studied by RT-PCR and using Real Time PCR assay, we monitored the CD3, p21, TNF-α and IFN-γ mRNA expression.

Results

Transfection of CD3p21 sense and antisense in mouse thyoma cell line (EL4-IL-2) resulted in modulation of mitogen-induced proliferation. The intramuscular injection of CD3p21 sense and antisense plasmid DNA into mice also modulated lymphocyte proliferation and mRNA expression of pro-inflammatory cytokines.

Conclusion

These results demonstrate a novel strategy of in vitro and in vivo transfer of p21 gene to T cells using CD3-promoter to achieve targeted inhibition of lymphocyte proliferation and immune activation.

Reciprocal role of cyclins and cyclin kinase inhibitor p21WAF1/CIP1 on lymphocyte proliferation, allo-immune activation and inflammation

Background

Immune activation that results due to the aberrant proliferation of lymphocytes leads to inflammation and graft rejection in organ transplant recipients. We hypothesize that the cell cycle control and inflammation are parallel events, inhibition of cellular proliferation by cyclin kinase inhibitor specifically p21 will limit inflammation and prevent allograft rejection.

Methods

We performed in vitro and in vivo studies using lymphocytes, and rat heart transplant model to understand the role of cyclins and p21 on mitogen and allo-induced lymphocyte activation and inflammation. Lymphocyte proliferation was studied by ³H-thymidine uptake assay and mRNA expression was studied RT-PCR.

Results

Activation of allo- and mitogen stimulated lymphocytes resulted in increased expression of cyclins, IL-2 and pro-inflammatory cytokines, which was inhibited by cyclosporine. The over-expression of p21 prolonged graft survival in a completely mismatched rat heart transplant model resulted by inhibiting circulating and intra-graft expression of proinflammatory cytokines.

Conclusion

Cyclins play a significant role in transplant-induced immune activation and p21 over-expression has potential to inhibit T cell activation and inflammation. The results from this study will permit the design of alternate strategies by controlling cell cycle progression to achieve immunosuppression in transplantation.

Recombinant p21 protein inhibits lymphocyte proliferation and transcription factors

Cellular proliferation determines the events leading to the initiation and development of inflammation, immune activation, cancer, atherogenesis, and other disorders associated with aberrant cell proliferation. Cyclin inhibitor p21 plays a unique role in limiting cell cycle progression. However, its effectiveness can only be demonstrated with direct in vitro and in vivo delivery to control aberrant proliferation. We demonstrate that using a protein-transducing domain p21 protein a) localizes within the nuclear compartments of cells, b) interacts with transcription factors, NF-kappaB, and NFATs (NFATc and NFATp), and c) inhibits lymphocyte proliferation and expression of proinflammatory cytokines. This study using lymphocyte proliferation as a model suggests that the recombinant p21 protein can directly be delivered as a therapeutic protein to provide a novel, viable, and powerful strategy to limit proliferation, inflammation, alloimmune activation, cancer, and vascular proliferative disorders such as atherosclerosis.

Concerted effect of transforming growth factor-β, cyclin inhibitor p21, and c-mycon smooth muscle cell proliferation

Increased aortic smooth muscle cell (SMC) proliferation is a key event in the pathogenesis of atherosclerosis. Transforming growth factor-β (TGF-β) is one of the potent inhibitors of SMC proliferation. The purpose of this study was 1) to explore the effect of TGF-β inhibition on proliferation of SMC and expression of growth regulatory molecules like p21 and c- myc and 2) to determine whether restoration of cell cycle regulatory molecules normalizes the altered proliferation. To test the role of TGF-β in SMC proliferation, using antisense plasmid DNA, we inhibited TGF-β gene from aortic SMC, which resulted in a significant increase ( P < 0.03) in proliferation (studied by quantifying new DNA synthesis with [3H]thymidine uptake assay). In TGF-β-altered SMC (TASMC), the mRNA expression (studied by RT-PCR) of c- myc was increased whereas that of the cyclin inhibitor p21 was completely inhibited. Using p21 sense plasmid DNA, we transfected p21 gene in TASMC, which restored p21 mRNA and protein expression and decreased proliferation ( P < 0.002) in TASMC. Similar treatment with c- myc antisense oligonucleotides significantly ( P < 0.001) decreased the proliferation of TASMC. TASMC also exhibited alteration in morphological changes in SMC but returned to normal with treatment of p21 and TGF-β sense plasmid DNA. Two-dimensional gel electrophoresis analysis of SMC and TASMC demonstrated differential expression of proteins relevant to cellular proliferation and atherosclerosis. This study uniquely analyzes the effect of TGF-β at the molecular level on proliferation of SMC and on cell cycle regulatory molecules, implicating their potential role in the pathogenesis of atherosclerosis.

The immunosuppressive agent tacrolimus induces p21WAF/CIP1WAF1/CIP1 via TGF-beta secretion

Tacrolimus (Tac) is more immunosuppressive drug compared to cyclosporine (CsA). Our previous studies have demonstrated that CsA induces the expression of p21WAF/CIP1 expression. In this study we explored if like CsA, Tac also induces expression of p21WAF/CIP1. We also determined if induction of p21WAF/CIP1 by Tac is dependent on TGF-beta. Using RT-PCR and Western blot analysis, we studied the induction of p21WAF/CIP1 mRNA and protein in human T cells and A-549 cells (human lung adenocarcinoma cells) by Tac. The stimulation of p21WAF/CIP1 promoter activity was studied by luciferase assay using p21WAF/CIP1-luc, chimeric plasmid DNA containing a p21WAF/CIP1 promoter segment and luciferase reporter gene. Using anti-TGF-beta antibody, we studied if induction of p21WAF/CIP1 by tacrolimus is dependent on TGF-beta. The results demonstrate that Tac induced p21WAF/CIP1 mRNA and protein expression as well as stimulated its promoter activity in T cells and A-549 cells. The induction of p21WAF/CIP1 expression by tacrolimus was dependent on TGF-beta since a neutralizing anti-TGF-beta antibody inhibited induction of p21WAF/CIP1in A-549 cells. These data support the hypothesis that cyclin inhibitor p21WAF/CIP1 might represent a unified mediator of the anti-proliferative effects of Tac and other immunosuppressive agents. Strategies involving p21WAF/CIP1 induction should be considered a viable alternative strategy to achieve immunosuppression possibly with reduced toxicity associated with current immunosuppression.

Relative quantification of mRNA levels in Jurkat T cells with RT-real time-PCR (RT-rt-PCR): new possibilities for the screening of anti-inflammatory and cytotoxic compounds

PURPOSE

Quantification of the pro-inflammatory action of mitogens on mRNA levels of growth-related genes, transcription factors, and cytokines in T cells as markers for the screening of compounds with immunomodulatory, anti-inflammatory or cytotoxic potential.

METHOD

A reverse transcription-real time-polymerase chain reaction assay with TaqMan probes was developed. Jurkat T cells were treated with cyclosporin A, hypericin, capsaicin, and catechin before phorbol 12-myristate 13-acetate stimulation, and their effects on the relative mRNA levels were determined. A cell viability assay was performed in parallel.

RESULTS

Cyclosporin A and capsaicin were potent inhibitors of PMA-induced cytokine transcription. Cyclosporin A further targeted cyclin D1 transcription. Capsaicin exhibited no effects on the cell viability at low concentrations, whereas cyclosporin A did. Hypericin down-regulated nearly all investigated mRNAs, resulting in a strong time-dependent cytotoxicity. Catechin showed no effects on mRNA levels and cell viability.

CONCLUSIONS

The inhibition of the up-regulation of mRNA levels of cytokines points to a specific anti-inflammatory potential of capsaicin. Hypericin showed no specific effects on the mRNA expression. The overall decrease of mRNA levels is probably an early indication of the strong cytotoxic effect observed after 48 h. Therefore, quantification of mRNA levels by reverse transcription-real time-polymerase chain reaction is, in combination with the monitoring of cell viability, a valuable tool to distinguish between specific immunomodulatory and cytotoxic effects in vitro.

G1/S cell cycle arrest provoked in human T cells by antibody to CD26

CD26 is T cell costimulatory molecule with dipeptidyl peptidase IV (DPPIV) enzyme activity located in its extracellular region. The expression of CD26 is enhanced after activation of T cells, while it is preferentially expressed on a subset of CD4+ memory T cells in the resting state. In this paper, we demonstrate that binding of the soluble anti-CD26 monoclonal antibody (mAb) 1F7 inhibits human T-cell growth and proliferation in both CD26-transfected Jurkat T-cell lines and human T-cell clones by inducing G1/S arrest, which is associated with enhancement of p21Cip1 expression. This effect depends on the DPPIV enzyme activity of the CD26 molecule. Moreover, we show that expression of p21Cip1 after treatment with the anti-CD26 mAb 1F7 appears to be induced through activation of extracellular signal-regulated kinase (ERK) pathway. These data thus suggest that anti-CD26 treatment may have potential use in the clinical setting involving activated T cell dysregulation, including autoimmune disorders and graft-vs.-host disease.