Inhibition of S-adenosyl-L-homocysteine hydrolase alleviates alloimmune response by down-regulating CD4+ T-cell activation in a mouse heart transplantation model

One-carbon metabolism shapes T cell immunity in cancer

One-carbon metabolism (1CM), comprising folate metabolism and methionine metabolism, serves as an important mechanism for cellular energy provision and the production of vital signaling molecules, including single-carbon moieties. Its regulation is instrumental in sustaining the proliferation of cancer cells and facilitating metastasis; in addition, recent research has shed light on its impact on the efficacy of T cell-mediated immunotherapy. In this review, we consolidate current insights into how 1CM affects T cell activation, differentiation, and functionality. Furthermore, we delve into the strategies for modulating 1CM in both T cells and tumor cells to enhance the efficacy of adoptively transferred T cells, overcome metabolic challenges in the tumor microenvironment (TME), and maximize the benefits of T cell-mediated immunotherapy.

Retinoic acid-inducible gene-1 knockdown induces immature properties in dendritic cells and prolongs the survival time of allograft mice

BACKGROUND

The mature state of dendritic cells (DCs) determines their ability to regulate immune responses. Retinoic acid-inducible gene-1 (RIG-1) plays a critical role in DC activation and maturation. RIG-1 activation triggers mitogen-activated protein kinase and nuclear factor-kappa B signal transduction. In this study, we aimed to investigate the effects of inhibiting RIG-1 expression in DCs and its potential in inducing immune tolerance.

METHODS

DCs were transduced with the recombinant lentiviral vector (Lv) to inhibit RIG-1 expression. A murine islet and skin transplantation model were constructed to find out whether DC-DDX58-RNAi could prolong allograft survival. The phenotypes of DCs and T-cells were analyzed using flow cytometry. Cytokines in serum were detected by the enzyme-linked immunosorbent assay. Protein levels were determined by Western blot.

RESULTS

RIG-1-deficient DCs had low expression of costimulatory molecules and major histocompatibility complex and a strong phagocytic ability. DC-DDX58-RNAi induced regulatory T cell differentiation in the transplant recipient spleens. The DC-DDX58-RNAi-treated recipients showed satisfactory islet allograft function and longer survival time.

CONCLUSION

Inhibition of RIG-1 with DDX58-RNAi prevented the activation and maturation of the DCs, affected T cell differentiation, protected the biological function of the allograft, and prolonged graft survival. These findings may have important therapeutic implications for new immunomodulatory regimens.

In vitro inhibition of Pseudomonas aeruginosa PAO1 biofilm formation by DZ2002 through regulation of extracellular DNA and alginate production

Introduction

Pseudomonas aeruginosa (P. aeruginosa) is a common pathogen associated with biofilm infections, which can lead to persistent infections. Therefore, there is an urgent need to develop new anti-biofilm drugs. DZ2002 is a reversible inhibitor that targets S-adenosylhomocysteine hydrolase and possesses anti-inflammatory and immune-regulatory activities. However, its anti-biofilm activity has not been reported yet.

Methods and results

Therefore, we investigated the effect of DZ2002 on P. aeruginosa PAO1 biofilm formation by crystal violet staining (CV), real-time quantitative polymerase chain reaction (RT-qPCR) and confocal laser scanning microscopy (CLSM). The results indicated that although DZ2002 didn't affect the growth of planktonic PAO1, it could significantly inhibit the formation of mature biofilms. During the inhibition of biofilm formation by DZ2002, there was a parallel decrease in the synthesis of alginate and the expression level of alginate genes, along with a weakening of swarming motility. However, these results were unrelated to the expression of lasI, lasR, rhII, rhIR. Additionally, we also found that after treatment with DZ2002, the biofilms and extracellular DNA content of PAO1 were significantly reduced. Molecular docking results further confirmed that DZ2002 had a strong binding affinity with the active site of S-adenosylhomocysteine hydrolase (SahH) of PAO1.

Discussion

In summary, our results indicated that DZ2002 may interact with SahH in PAO1, inhibiting the formation of mature biofilms by downregulating alginate synthesis, extracellular DNA production and swarming motility. These findings demonstrate the potential value of DZ2002 in treating biofilm infections associated with P. aeruginosa.

Targeting one-carbon metabolism for cancer immunotherapy

BACKGROUND

One-carbon (1C) metabolism is a metabolic network that plays essential roles in biological reactions. In 1C metabolism, a series of nutrients are used to fuel metabolic pathways, including nucleotide metabolism, amino acid metabolism, cellular redox defence and epigenetic maintenance. At present, 1C metabolism is considered the hallmark of cancer. The 1C units obtained from the metabolic pathways increase the proliferation rate of cancer cells. In addition, anticancer drugs, such as methotrexate, which target 1C metabolism, have long been used in the clinic. In terms of immunotherapy, 1C metabolism has been used to explore biomarkers connected with immunotherapy response and immune-related adverse events in patients.

METHODS

We collected numerous literatures to explain the roles of one-carbon metabolism in cancer immunotherapy.

RESULTS

In this review, we focus on the important pathways in 1C metabolism and the function of 1C metabolism enzymes in cancer immunotherapy. Then, we summarise the inhibitors acting on 1C metabolism and their potential application on cancer immunotherapy. Finally, we provide a viewpoint and conclusion regarding the opportunities and challenges of targeting 1C metabolism for cancer immunotherapy in clinical practicability in the future.

CONCLUSION

Targeting one-carbon metabolism is useful for cancer immunotherapy.

Synthesis and biological evaluation of novel pentanediamide derivatives as S-adenosyl-l-homocysteine hydrolase inhibitors

A series of novel pentanediamide derivatives were designed, synthesized and evaluated as S-adenosyl-l-homocysteine hydrolase (SAHase) inhibitors in this study. Some compounds showed good inhibitory activity against SAHase. The optimal compound 7i showed good inhibitory activity against SAHase with IC₅₀ value of 3.58 ± 0.19 μM, cytotoxicity with IC₅₀ values ranging from 13.16 ± 1.44 to 21.23 ± 0.73 μM against four tumor cell lines (MCF-7, A549, MGC-803, Hela) and very weak cytotoxicity (IC₅₀ = 84.22 ± 1.89 μM) on normal LO2 cells. In addition, compound 7i showed potency against respiratory syncytial virus with EC₅₀ value of 27.4 μM and selectivity index of 6.84. Further molecular simulation study suggested that compound 7i had good ADMET properties, and strongly binds to the active site of SAHase. In summary, compound 7i could serve as a new lead compound for further screening novel non-adenosine SAHase inhibitors.

Methionine cycle-dependent regulation of T cells in cancer immunity

The methionine cycle comprises a series of reactions that catabolizes and regenerates methionine. This process is crucial to many cellular functions, including polyamine synthesis, DNA synthesis, redox balance, and DNA and histone methylation. In response to antigens, T cells activate the methionine cycle to support proliferation and differentiation, indicating the importance of the methionine cycle to T cell immunity. In cancer, T cells serve as important effectors of adaptive immunity by directly killing cancerous cells. However, the tumor microenvironment can induce a state of T cell exhaustion by regulating the methionine metabolism of T cells, posing a barrier to both endogenous T cell responses and T cell immunotherapy. Here we review the role of methionine cycle metabolites in regulating the activation and effector function of T cells and explore the mechanism by which tumor cells exploit the methionine pathway as a means of immune evasion. Finally, we discuss new perspectives on reprogramming the methionine cycle of T cells to enhance anti-tumor immunotherapy.