BET Protein Inhibition Prolongs Cardiac Transplant Survival via Enhanced Myocardial Autophagy

Lactobacillus rhamnosus HN001 facilitates the efficacy of dual PI3K/mTOR inhibition prolonging cardiac transplant survival and enhancing antitumor effect

Solid organ transplantation is a crucial treatment for patients who have reached the end stage of heart, lung, kidney, or liver failure. However, the likelihood of developing cancer post-transplantation increases. Additionally, primary malignant tumors remain a major obstacle to the long-term survival of transplanted organs. Therefore, it is essential to investigate effective therapies that can boost the immune system's ability to combat cancer and prevent allograft rejection. We established a mouse orthotopic liver tumor model and conducted allogeneic heterotopic heart transplantation. Various treatments were administered, and survival curves were generated using the Kaplan-Meier method. We also collected graft samples and measured inflammatory cytokine levels in the serum using an inflammatory array. The specificity of the histochemical techniques was tested by staining sections. We administered a combination therapy of phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) dual inhibitor BEZ235 and Lactobacillus rhamnosus HN001 to primary liver cancer model mice with cardiac allografts. Consistent with our prior findings, L. rhamnosus HN001 alleviated the intestinal flora imbalance caused by BEZ235. Our previous research confirmed that the combination of BEZ235 and L. rhamnosus HN001 significantly prolonged cardiac transplant survival.

IMPORTANCE

We observed that the combination of phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) dual inhibitor BEZ235 and Lactobacillus rhamnosus HN001 notably prolonged cardiac transplant survival while also inhibiting the progression of primary liver cancer. The combination therapy was efficacious in treating antitumor immunity and allograft rejection, as demonstrated by the efficacy results. We also found that this phenomenon was accompanied by the regulation of inflammatory IL-6 expression. Our study presents a novel and effective therapeutic approach to address antitumor immunity and prevent allograft rejection.

JQ1 attenuates contrast-induced acute kidney injury through the upregulation of autophagy and inhibition of inflammation

PURPOSE

Contrast-induced acute kidney injury (CI-AKI) is the third most common cause of hospital-acquired AKI. However, there is a paucity of efficacious interventions for the management of CI-AKI. Here, we aim to investigate the effects of JQ1 in CI-AKI and provide theoretical data and a  foundation for  novel ideas for the clinical treatment of CI-AKI.

METHODS

In this study, we performed in vivo and in vitro experiments with mice and HK2 cells injury models respectively. The levels of serum creatinine (Cr) and blood urea nitrogen (BUN) were determined by an automatic analyzer for the measurements of renal function. The viability of HK-2 cells was analyzed using the Cell Counting Kit-8 (CCK-8) kit. Additionally, the kidney changes in the mice were detected using histopathology (H&E) and immunofluorescent staining. The mRNA and protein expressions were assessed using Quantitative real-time PCR and western blot, respectively. Autophagy and apoptosis was analyzed by Transmission electron microscopy (TEM) and TUNEL assay respectively.

RESULTS

The results demonstrated that JQ1 exhibited potency of attenuating CI-AKI in mouse and HK2 cells. JQ1 increased the expression levels of Atg5, Atg7 and LC3B-II, and decreased the protein levels of p62 in the kidney and HK-2 cells. However, the combined use of JQ1 with chloroquine reversed the effects of JQ1. JQ1 also inhibited the inflammatory cells and downregulated the expression of some inflammatory cytokines (IL-6, IL-1β, TNF-α, and IFN-γ).

CONCLUSION

JQ1 protects against CI-AKI by promoting autophagy and inhibiting inflammation and JQ1 may be a promising therapeutic strategy for CI-AKI.

Targeting SIRT1 synergistically improves the antitumor effect of JQ-1 in hepatocellular carcinoma

Bromodomain and extraterminal domain protein inhibitors have shown therapeutic promise in hepatocellular carcinoma. However, resistance to bromodomain and extraterminal domain protein inhibitors has emerged in preclinical trials, presenting an immense clinical challenge, and the mechanisms are unclear. In this study, we found that overexpression of SIRT1 induced by JQ-1, a bromodomain and extraterminal domain protein inhibitor, may confer resistance to JQ-1 in hepatocellular carcinoma. SIRT1 protein expression was higher in hepatocellular carcinoma tissues than in normal tissues, and this phenotype was correlated with a poor prognosis. Cotreatment with JQ-1 and the SIRT1 inhibitor EX527 synergistically suppressed proliferation and blocked cell cycle progression in hepatocellular carcinoma cells. Combined administration of JQ-1 and EX527 successfully reduced the tumor burden in vivo. In addition, JQ-1 mediated AMPK/p-AMPK axis activation to upregulate SIRT1 protein expression and enhanced autophagy to inhibit cell apoptosis. Activation of AMPK could alleviate the antitumor effect of the combination of JQ-1 and EX527 on hepatocellular carcinoma cells. Furthermore, inhibition of SIRT1 further enhanced the antitumor effect of JQ-1 by blocking protective autophagy in hepatocellular carcinoma. Our study proposes a novel and efficacious therapeutic strategy of a BET inhibitor combined with a SIRT1 inhibitor for hepatocellular carcinoma.

Monomethyl fumarate prevents alloimmune rejection in mouse heart transplantation by inducing tolerogenic dendritic cells

Dendritic cells (DCs) are important targets for eliciting allograft rejection after transplantation. Previous studies have demonstrated that metabolic reprogramming of DCs can transform their immune functions and induce their differentiation into tolerogenic DCs. In this study, we aim to investigate the protective effects and mechanisms of monomethyl fumarate (MMF), a bioactive metabolite of fumaric acid esters, in a mouse model of allogeneic heart transplantation. Bone marrow-derived DCs are harvested and treated with MMF to determine the impact of MMF on the phenotype and immunosuppressive function of DCs by flow cytometry and T-cell proliferation assays. RNA sequencing and Seahorse analyses are performed for mature DCs and MMF-treated DCs (MMF-DCs) to investigate the underlying mechanism. Our results show that MMF prolongs the survival time of heart grafts and inhibits the activation of DCs in vivo. MMF-DCs exhibit a tolerogenic phenotype and function in vitro. RNA sequencing and Seahorse analyses reveal that MMF activates the Nrf2 pathway and mediates metabolic reprogramming. Additionally, MMF-DC infusion prolongs cardiac allograft survival, induces regulatory T cells, and inhibits T-cell activation. MMF prevents allograft rejection in mouse heart transplantation by inducing tolerogenic DCs.

The multifunctional roles of autophagy in the innate immune response: Implications for regulation of transplantation rejection

Organ transplantation is the main treatment for end-stage organ failure, which has rescued tens of thousands of lives. Immune rejection is the main factor affecting the survival of transplanted organs. How to suppress immune rejection is an important goal of transplantation research. A graft first triggers innate immune responses, leading to graft inflammation, tissue injury and cell death, followed by adaptive immune activation. At present, the importance of innate immunity in graft rejection is poorly understood. Autophagy, an evolutionarily conserved intracellular degradation system, is proven to be involved in regulating innate immune response following graft transplants. Moreover, there is evidence indicating that autophagy can regulate graft dysfunction. Although the specific mechanism by which autophagy affects graft rejection remains unclear, autophagy is involved in innate immune signal transduction, inflammatory response, and various forms of cell death after organ transplantation. This review summarizes how autophagy regulates these processes and proposes potential targets for alleviating immune rejection.

An efficient combination immunotherapy for antitumor immunity without accelerating cardiac allograft rejection

Immunotherapy with immune checkpoint inhibitors (ICIs), including antibodies against programmed cell death protein-1 (PD-1) and its receptor programmed cell death ligand-1 (PD-L1), represents a promising systematic treatment for advanced human malignancies. Transplantation remains the ultimate therapy for end-stage organ diseases. However, the efficacy of ICI treatment in solid organ transplant (SOT) recipients remains controversial. We established a transgenic primary liver cancer mouse model and performed allogeneic heterotopic heart transplantation. Different treatments were performed and survival curves were calculated. Graft samples were collected, and immune cells and the cell surface expression of PD-L1 were analysed by flow cytometry. Inflammatory cytokine levels in the serum were measured by an inflammatory array. The specificity of the histochemical techniques was tested by staining sections. A combination immunotherapy comprising a BET protein inhibitor (JQ1) and an immune checkpoint inhibitor (anti-PD-L1 antibody) was administered to primary liver cancer model mice bearing cardiac allografts. Interestingly, the combination immunotherapy effectively suppressed the progression of primary liver cancer but did not accelerate allograft rejection. In accordance with our previous findings, BET protein inhibition enhances the expression of a putative membrane transporter (Rab8A), which upregulates the expression of PD-L1 on the plasma membrane in a transgenic primary liver cancer mouse model. This may be a crucial mechanism of tumour progression arrest. Our data showed that heart transplantation upregulated the expression of the proinflammatory factor IFN-γ and suggested that BET protein inhibition (with JQ1) decreased PD-L1 expression in heart tissues after cardiac transplantation. This phenomenon was accompanied by enhanced infiltration of inflammatory IFN-γ. Our study provides a novel and efficient therapeutic strategy for SOT recipients.

Lactobacillus rhamnosus HN001 Ameliorates BEZ235-Induced Intestinal Dysbiosis and Prolongs Cardiac Transplant Survival

Cardiac allograft rejection remains a major factor limiting long-term engraftment after transplantation. A novel phosphoinositide 3-kinase (PI3K)/mTOR dual inhibitor, BEZ235, prolonged cardiac allograft survival by effectively suppressing activation of the PI3K/serine/threonine kinase (AKT)/mTOR pathway. However, long-term usage of pharmacological immunosuppressant drugs can cause intestinal microbiota dysbiosis. We established mouse models of allogeneic heterotopic heart transplantation with different treatments. Fecal samples were collected and subjected to 16S rRNA sequencing and targeted fecal metabolomic analysis. Graft samples were taken for immune cell detection by flow cytometry. Inflammatory cytokines in serum were quantified by enzyme-linked immunosorbent assay (ELISA). Compared to single-target approaches (IC-87114 and rapamycin), BEZ235 more efficiently prolongs cardiac transplant survival. Interestingly, BEZ235 reduces the diversity and abundance of the intestinal microbiota community. We demonstrated that Lactobacillus rhamnosus HN001 rescues the intestinal microbiota imbalance induced by BEZ235. IMPORTANCE Our data confirmed that the combination of BEZ235 and Lactobacillus rhamnosus HN001 significantly prolongs cardiac transplant survival. A main metabolic product of Lactobacillus rhamnosus HN001, propionic acid (PA), enriches regulatory T (Treg) cells and serves as a potent immunomodulatory supplement to BEZ235. Our study provides a novel and efficient therapeutic strategy for transplant recipients.

BEZ235 Prolongs Murine Cardiac Allograft Survival Through the Autophagy Pathway

BACKGROUND

BEZ235, a dual PI3K/mTOR inhibitor, has shown a critical impact in the treatment of cancers, with the ability to induce autophagy. However, the effects of BEZ235 in heart transplant have been rarely investigated. The aim of this study was to evaluate the potency of BEZ235 in cardiac allograft survival.

METHODS

BEZ235 was administered during the perioperative period of syngeneic or allogeneic heart transplant to assess survival time. Next, the autophagy signaling pathway and the proinflammatory cytokines were analyzed. Furthermore, a cardiomyocytes-specific ATG5 gene-ablated mouse was used to confirm the results.

RESULTS

BEZ235 treatment significantly prolonged the survival of the cardiac graft and reduced the infiltration of inflammatory cells. The expression levels of autophagy proteins were increased in the BEZ235 treatment group compared to the control group, but the therapeutic effect of BEZ235 was weakened in the cardiomyocytes-specific ATG5 gene-ablated mice. Moreover, BEZ235 significantly downregulated the expression of IL-1β, IL-2, and TNF-α.

CONCLUSIONS

It seems BEZ235 could induce autophagy and prolonged murine cardiac allograft survival in a mechanism that involved the autophagy pathway and changed multiple inflammatory factors. This study has proposed a theoretical foundation for the strong connection between mTOR-induced autophagy and heart transplant.

Enhanced autophagy alleviated corneal allograft rejection via inhibiting NLRP3 inflammasome activity

Autophagy has been reported to be involved in many aspects of innate and adaptive immunity. Manipulating autophagy is recognized as a promising therapeutic approach for treating immunological diseases, including allograft rejection, and graft-versus-host disease. However, whether autophagy was closely associated with the pathogenesis of corneal allograft rejection remains largely unknown. Here, we showed that rapamycin (RAPA)-induced autophagy alleviated corneal allograft rejection. By contrast, blocking autophagic activity using 3-methyladeine (3-MA) aggravated corneal transplantation rejection. Mechanistically, we revealed that the enhanced autophagic turnover by RAPA inhibited NLRP3 inflammasome activity through NLRP3 degradation. While blocking the fusion of autophagosomes with lysosomes by bafilomycin A1(BafA1), the reduced NLRP3 inflammasome activity induced by RAPA was significantly restored, with increased protein levels of NLRP3 and cleaved Casp-1(p10), as well as IL-1β secretion. Moreover, we further revealed that pharmacologically blocking NLRP3 inflammasome signaling prolonged the survival of corneal allografts. Taken together, these findings underscored the critical roles of enhanced autophagy in treating corneal allograft rejection, which provided an alternative intervention strategy to control corneal transplantation rejection.

Kaempferol alleviates corneal transplantation rejection by inhibiting NLRP3 inflammasome activation and macrophage M1 polarization via promoting autophagy

Corneal transplantation rejection remains a major threat to the success rate of high-risk patients. Given the many side effects presented by traditional immunosuppressants, there is an urgency to clarify the mechanism of corneal transplantation rejection and to identify new therapeutic targets. Kaempferol is a natural flavonoid that has been proven in various studies to possess anti-inflammatory, antioxidant, anticancer, and neuroprotective properties. However, the effect of Ka on corneal transplantation remains largely unexplored. To address this, both at the in vivo and in vitro levels, we established a model of corneal allograft transplantation in Wistar rats and an LPS-induced inflammatory model using human THP-1-derived macrophages. In the transplantation experiments, we observed an enhancement of mRNA and protein level in the NLRP3/IL-1 β axis and in M1 macrophage polarization post-operation. In groups to which kaempferol intraperitoneal injections were administered, this response was effectively reduced. However, the effect of kaempferol was reversed after the application of autophagy inhibitors. Similarly, in the inflammatory model, we found that different concentrations of kaempferol reduced the LPS-induced M1 polarization and NLRP3 inflammasome activation. Moreover, we confirmed that kaempferol induced autophagy and that autophagy inhibitors reversed this effect in macrophages. In conclusion, we found that kaempferol can inhibit the activation of NLRP3 inflammasomes by inducing autophagy, thus inhibiting macrophage polarization, and ultimately alleviating corneal transplantation rejection. Thus, our study suggests that kaempferol is a potential therapeutic agent in the treatment of allograft rejection.

The mTOR Deficiency in Monocytic Myeloid-Derived Suppressor Cells Protects Mouse Cardiac Allografts by Inducing Allograft Tolerance

Background

Myeloid-derived suppressor cells (MDSCs) can prevent allograft rejection and induce immune tolerance in transplantation models. Previous studies have demonstrated that inhibition of mTOR signaling can enhance the MDSC protective effect in heart transplantation (HTx) by promoting MDSC expansion. In addition, mTOR inhibition is related to autophagy. The present study investigated the protective mechanism of mTOR-deficient monocytic MDSCs (M-MDSCs) in mouse HTx.

Methods

Myeloid-specific mTOR conditional knockout mice were generated to obtain mTOR-/- M-MDSCs. The proliferation and immunosuppressive function of mTOR-/- M-MDSCs were determined by flow cytometry and T cell proliferation assays. The mTOR-/- M-MDSC intracellular autophagy levels were determined using western blotting and electron microscopy. RNAseq analysis was performed for wild-type (WT) and mTOR-/- M-MDSCs. Allogeneic HTx mouse model was established and treated with WT or mTOR-/- M-MDSCs. Enzyme-linked immunosorbent assay, flow cytometry, and immunohistochemistry assays were performed to determine WT and mTOR-/- M-MDSC-induced immune tolerance.

Results

The mTOR deficiency promoted M-MDSC differentiation and enhanced intracellular autophagy levels in vivo and in vitro. mTOR deficiency also enhanced the immunosuppressive function of M-MDSCs. In addition, infusing with WT and mTOR-/- M-MDSCs prolonged cardiac allograft survival and established immune tolerance in recipient mice by inhibiting T cell activation and inducing regulatory T cells.

Conclusion

mTOR deficiency enhances the immunosuppressive function of M-MDSCs and prolongs mouse cardiac allograft survival.

The BRD4 inhibitor JQ1 protects against chronic obstructive pulmonary disease in mice by suppressing NF-κB activation

OBJECTIVE

To examine the effect of the BRD4 inhibitor JQ1 on mice with chronic obstructive pulmonary disease (COPD) via NF-κB.

METHODS

COPD models constructed by exposure to cigarette smoke and intratracheal instillation of lipopolysaccharides (LPS) in mice were treated with JQ1 (15, 25 or 50 mg/kg). HE staining was performed to observe histopathological changes in the lung tissues. Enzyme-linked immunosorbent assays (ELISAs) were used to measure the levels of IL-10, IFN-γ, IL-17, IL-1β, IL-6, TNF-α, MMP-2, MMP-9, MDA, SOD, T-AOC and HO-1, and gelatin zymography assays were used to examine MMP-2 and MMP-9 activity. A TransAMTM NF-κB p65 detection kit was used to test NF-κB p65/DNA binding activity. Western blotting was conducted to analyze NF-κB p65 in the nucleus and its acetylation.

RESULTS

JQ1 dose-dependently improved the histopathological changes in the lung tissues and decreased the mean linear intercept (MLI), destructive index and inflammatory score of the mice with COPD. The mice with COPD showed increased levels of MMP-2, MMP-9, IFN-γ, IL-17, IL-1β, IL-6 and TNF-α with decreased IL-10 level; these changes were reversed by JQ1 in a dose-dependent manner. In addition, JQ1 reduced the MDA level and increased the SOD, HO-1 and T-AOC levels in mice with COPD, with suppression of NF-κB p65 expression in the nucleus, NF-κB/p65 (Lys310) acetylation and NF-κB p65/DNA binding activity in the lung tissues.

CONCLUSION

The BRD4 inhibitor JQ1 can downregulate MMP-2 and MMP-9 expression, reduce inflammatory responses, and alleviate oxidative stress in mice with COPD, and this mechanism might be related to the inhibition of NF-κB.