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

Immunoengineered MXene nanosystem for mitigation of alloantigen presentation and prevention of transplant vasculopathy

MXenes are an emerging class of nanomaterials with significant potential for applications in nanomedicine. Amongst MXene technologies, titanium carbide (Ti₃C₂T_x) nanomaterials are the most mature and have received significant attention to tackle longstanding clinical challenges due to its tailored physical and material properties. Cardiac allograft vasculopathy is an aggressive form of atherosclerosis and a major cause of mortality among patients with heart transplants. Blood vessel endothelial cells (ECs) stimulate alloreactive T-lymphocytes to result in sustained inflammation. Herein, we report the first application of Ti₃C₂T_x MXene nanosheets for prevention of allograft vasculopathy. MXene nanosheets interacted with human ECs and downregulated the expression of genes involved in alloantigen presentation, and consequently reduced the activation of allogeneic lymphocytes. RNA-Seq analysis of lymphocytes showed that treatment with MXene downregulated genes responsible for transplant-induced T-cell activation, cell-mediated rejection, and development of allograft vasculopathy. In an in vivo rat model of allograft vasculopathy, treatment with MXene reduced lymphocyte infiltration and preserved medial smooth muscle cell integrity within transplanted aortic allografts. These findings highlight the potential of Ti₃C₂T_x MXene in treatment of allograft vasculopathy and inflammatory diseases.

Increased expression of CDKN1A/p21 in HIV-1 controllers is correlated with upregulation of ZC3H12A/MCPIP1

Background

Some multifunctional cellular proteins, as the monocyte chemotactic protein-induced protein 1 (ZC3H12A/MCPIP1) and the cyclin-dependent kinase inhibitor CDKN1A/p21, are able to modulate the cellular susceptibility to the human immunodeficiency virus type 1 (HIV-1). Several studies showed that CDKN1A/p21 is expressed at high levels ex vivo in cells from individuals who naturally control HIV-1 replication (HIC) and a recent study supports a coordinate regulation of ZC3H12A/MCPIP1 and CDKN1A/p21 transcripts in a model of renal carcinoma cells. Here, we explored the potential associations between mRNA expression of ZC3H12A/MCPIP1 and CDKN1A/p21 in HIC sustaining undetectable (elite controllers–EC) or low (viremic controllers–VC) viral loads.

Results

We found a selective upregulation of ZC3H12A/MCPIP1 and CDKN1A/p21 mRNA levels in PBMC from HIC compared with both ART–suppressed and HIV–negative control groups (P≤ 0.02) and higher MCPIP1 and p21 proteins levels in HIC than in HIV-1 negative subjects. There was a moderate positive correlation (r ≥ 0.57; P ≤ 0.014) between expressions of both transcripts in HIC and in HIC combined with control groups. We found positive correlations between the mRNA level of CDKN1A/p21 with activated CD4⁺ T cells levels in HIC (r ≥ 0.53; P ≤ 0.017) and between the mRNA levels of both CDKN1A/p21 (r = 0.74; P = 0.005) and ZC3H12A/MCPIP1 (r = 0.58; P = 0.040) with plasmatic levels of sCD14 in EC. Reanalysis of published transcriptomic data confirmed the positive association between ZC3H12A/MCPIP1 and CDKN1A/p21 mRNA levels in CD4⁺ T cells and monocytes from disparate cohorts of HIC and other HIV-positive control groups.

Conclusions

These data show for the first time the simultaneous upregulation of ZC3H12A/MCPIP1 and CDKN1A/p21 transcripts in the setting of natural suppression of HIV-1 replication in vivo and the positive correlation of the expression of these cellular factors in disparate cohorts of HIV-positive individuals. The existence of a common regulatory pathway connecting ZC3H12A/MCPIP1 and CDKN1A/p21 could have a synergistic effect on HIV-1 replication control and pharmacological manipulation of these multifunctional host factors may open novel therapeutic perspectives to prevent HIV-1 replication and disease progression.

Decitabine inhibits T cell proliferation via a novel TET2-dependent mechanism and exerts potent protective effect in mouse auto- and allo-immunity models

Multiple sclerosis (MS) is an autoimmune disease characterized by the dysregulated immune response including innate and adaptive immune responses. Increasing evidence has proven the importance of epigenetic modification in the progression of MS. Recent studies revealed that low-dose decitabine (Dec, 5-Aza-2′-deoxycytidine), which incorporates into replicating DNA and inhibits DNA methylation, could prevent experimental autoimmune encephalomyelitis (EAE) development by increasing the number of regulatory T cells (Tregs). Here, we showed that higher-dose decitabine relative to previous studies could also distinctly protect mice from EAE and allogeneic cardiac transplantation. Mechanistic studies revealed decitabine suppressed innate responses in EAE mice through inhibiting the activation of microglia and monocyte-derived macrophages that contributed to reduce the severity of EAE. Furthermore, differentiation of naïve CD4⁺ T cells into Th1 and Th17 cells was significantly suppressed by decitabine in vivo and in vitro. Though in vitro studies showed decitabine could induce Treg differentiation, there was no obvious change in the percentage of Tregs in Dec-treated EAE mice. Most importantly, we found that T cell proliferation was potently inhibited in vivo and in vitro by higher-dose decitabine through increased gene expression of the DNA dioxygenase TET2 which facilitated the expression of several cell cycle inhibitors. Collectively, our study provides novel mechanistic insights of using the epigenetic modifying agents in the management of both allo- and auto-immune responses.

T-Cell Surface Antigens and sCD30 as Biomarkers of the Risk of Rejection in Solid Organ Transplantation

T-cell activation is a characteristic of organ rejection. T cells, located in the draining lymph nodes of the transplant recipient, are faced with non-self-molecules presented by antigen presenting cells and become activated. Activated T cells are characterized by up-regulated surface antigens, such as costimulatory molecules, adhesion molecules, chemokine receptors, and major histocompatibility complex class II molecules. Surface antigen expression can be followed by flow cytometry using monoclonal antibodies in either cell function assays using donor-specific or nonspecific stimulation of isolated cells or whole blood and without stimulation on circulating lymphocytes. Molecules such as CD30 can be proteolytically cleaved off the surface of activated cells in vivo, and the determination of the soluble protein (sCD30) in serum or plasma is performed by immunoassays. As promising biomarkers for rejection and long-term transplant outcome, CD28 (costimulatory receptor for CD80 and CD86), CD154 (CD40 ligand), and sCD30 (tumor necrosis factor receptor superfamily, member 8) have been identified. Whereas cell function assays are time-consuming laboratory-developed tests which are difficult to standardize, commercial assays are frequently available for soluble proteins. Therefore, more data from clinical trials have been published for sCD30 compared with the surface antigens on activated T cells. This short review summarizes the association between selected surface antigens and immunosuppression, and rejection in solid organ transplantation.

Porphyromonas gingivalis promotes the cell cycle and inflammatory cytokine production in periodontal ligament fibroblasts

OBJECTIVE

The infection of Porphyromonas gingivalis (P. gingivalis) modulates host immune-inflammatory responses and destructs homeostasis of normal cell cycle, thereby leading to periodontal tissue destruction. Human periodontal ligament fibroblasts (PDLFs) are key players in the host immune responses and periodontal tissue regeneration. The aim of the present study was to discover the effects of P. gingivalis infection on the cell cycle and inflammatory cytokine production in PDLFs.

DESIGN

P. gingivalis infection model into PDLFs was established. The effect of P. gingivalis on the cell proliferation and cell cycle were detected by MTT and flow cytometry. The p21, cyclin D1 and cyclin E mRNA expression, p21 protein expression, as well as IL-6 and IL-8 protein levels were analyzed by RT-qPCR, Western blot and ELISA, respectively.

RESULTS

P. gingivalis promoted proliferation and G1 phase of PDLFs. G1 phase promotion was associated with the decreased level of p21 and the up-regulation of cyclin D1 at 6h, and with the increased level of cyclin E at 12h. Simultaneously, the immune-inflammatory response of PDLFs was initiated by P. gingivalis during the initial stage of infection, including the increased expressions of IL-6 and IL-8.

CONCLUSION

We confirmed that the infection of P. gingivalis could modulate the expression of PDLF genes, which control cell cycle and inflammatory cytokine production. Thus, P. gingivalis may contribute to the proliferation and inflammation of periodontal tissue.

Transcriptome analysis of peripheral blood mononuclear cells in human subjects following a 36 h fast provides evidence of effects on genes regulating inflammation, apoptosis and energy metabolism

There is growing interest in the potential health benefits of diets that involve regular periods of fasting. While animal studies have provided compelling evidence that feeding patterns such as alternate-day fasting can increase longevity and reduce incidence of many chronic diseases, the evidence from human studies is much more limited and equivocal. Additionally, although several candidate processes have been proposed to contribute to the health benefits observed in animals, the precise molecular mechanisms responsible remain to be elucidated. The study described here examined the effects of an extended fast on gene transcript profiles in peripheral blood mononuclear cells from ten apparently healthy subjects, comparing transcript profiles after an overnight fast, sampled on four occasions at weekly intervals, with those observed on a single occasion after a further 24 h of fasting. Analysis of the overnight fasted data revealed marked inter-individual differences, some of which were associated with parameters such as gender and subject body mass. For example, a striking positive association between body mass index and the expression of genes regulated by type 1 interferon was observed. Relatively subtle changes were observed following the extended fast. Nonetheless, the pattern of changes was consistent with stimulation of fatty acid oxidation, alterations in cell cycling and apoptosis and decreased expression of key pro-inflammatory genes. Stimulation of fatty acid oxidation is an expected response, most likely in all tissues, to fasting. The other processes highlighted provide indications of potential mechanisms that could contribute to the putative beneficial effects of intermittent fasting in humans.

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.

Brain injury expands the numbers of neural stem cells and progenitors in the SVZ by enhancing their responsiveness to EGF

There is an increase in the numbers of neural precursors in the SVZ (subventricular zone) after moderate ischaemic injuries, but the extent of stem cell expansion and the resultant cell regeneration is modest. Therefore our studies have focused on understanding the signals that regulate these processes towards achieving a more robust amplification of the stem/progenitor cell pool. The goal of the present study was to evaluate the role of the EGFR [EGF (epidermal growth factor) receptor] in the regenerative response of the neonatal SVZ to hypoxic/ischaemic injury. We show that injury recruits quiescent cells in the SVZ to proliferate, that they divide more rapidly and that there is increased EGFR expression on both putative stem cells and progenitors. With the amplification of the precursors in the SVZ after injury there is enhanced sensitivity to EGF, but not to FGF (fibroblast growth factor)-2. EGF-dependent SVZ precursor expansion, as measured using the neurosphere assay, is lost when the EGFR is pharmacologically inhibited, and forced expression of a constitutively active EGFR is sufficient to recapitulate the exaggerated proliferation of the neural stem/progenitors that is induced by hypoxic/ischaemic brain injury. Cumulatively, our results reveal that increased EGFR signalling precedes that increase in the abundance of the putative neural stem cells and our studies implicate the EGFR as a key regulator of the expansion of SVZ precursors in response to brain injury. Thus modulating EGFR signalling represents a potential target for therapies to enhance brain repair from endogenous neural precursors following hypoxic/ischaemic and other brain injuries.

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.