Inhibition of PI3K/Akt/mTOR pathway by ammonium chloride induced apoptosis and autophagy in MAC-T cell

Sirtuin 5 alleviates apoptosis and autophagy stimulated by ammonium chloride in bovine mammary epithelial cells

Ammonia (NH3) is an irritating and harmful gas that affects cell apoptosis and autophagy. Sirtuin 5 (SIRT5) has multiple enzymatic activities and regulates NH3-induced autophagy in tumor cells. In order to determine whether SIRT5 regulates NH3-induced bovine mammary epithelial cell apoptosis and autophagy, cells with SIRT5 overexpression or knockdown were generated and in addition, bovine mammary epithelial cells were treated with SIRT5 inhibitors. The results showed that SIRT5 overexpression reduced the content of NH3 and glutamate in cells by inhibiting glutaminase activity in glutamine metabolism, and reduced the ratio of ADP/ATP. The results in the SIRT5 knockdown and inhibitor groups were comparable, including increased content of NH3 and glutamate in cells by activating glutaminase activity, and an elevated ratio of ADP/ATP. It was further confirmed that SIRT5 inhibited the apoptosis and autophagy of bovine mammary epithelial cells through reverse transcription-quantitative PCR, western blot, flow cytometry with Annexin V FITC/PI staining and transmission electron microscopy. In addition, it was also found that the addition of LY294002 or Rapamycin inhibited the PI3K/Akt or mTOR kinase signal, decreasing the apoptosis and autophagy activities of bovine mammary epithelial cells induced by SIRT5-inhibited NH3. In summary, the PI3K/Akt/mTOR signal involved in NH3-induced cell autophagy and apoptosis relies on the regulation of SIRT5. This study provides a new theory for the use of NH3 to regulate bovine mammary epithelial cell apoptosis and autophagy, and provides guidance for improving the health and production performance of dairy cows.

BDE-47-mediated cytotoxicity via autophagy blockade in 3D HepaRG spheroids cultured in alginate microcapsules

Polybrominated Diphenyl Ethers (PBDEs) are a major class of brominated flame retardants, and their widespread use has led them to be considered contaminants with emerging concern. PBDEs have been detected in the indoor air, house dust, food, and all environmental compartments. The congener BDE-47 (2,2',4,4'-tetrabromodiphenyl ether) is the most prevalent, and hepatotoxicity, neurotoxicity, immunological changes, endocrine disruption, and genotoxic potential have been related to its exposure. Although the BDE-47 molecular toxicity pathway is directly related to intrinsic apoptotic cell death, the role of autophagy in BDE-47 toxicity remains unclear. In this context, three-dimensional cell culture has emerged as a good strategy for the replacement of animals in toxicological testing. Here, we used HepaRG spheroids cultured in alginate microcapsules to investigate the role of autophagy in BDE-47-mediated hepatotoxicity. We developed mature and functional HepaRG spheroids by culturing them in alginate microcapsules. Histological analysis revealed that HepaRG spheroids formed an extracellular matrix and stored glycogen. No apoptotic and/or necrotic cores were observed. BDE-47 showed concentration- and time-dependent cytotoxicity in HepaRG spheroids. In the early exposure period, BDE-47 initially disrupted mitochondrial activity and increased the formation of acid compartments that promoted the increase in autophagic activity; however, this autophagy was blocked, and long-term exposure to BDE-47 promoted efficient apoptotic cell death through autophagy blockade, as evidenced by an increased number of fragmented/condensed nuclei. Therefore, for the first time, we demonstrated BDE-47 toxicity and its cell pathway induces cell death using a three-dimensional liver cell culture, the HepaRG cell line.

Development of a centrifugal bioreactor for rapid expansion of CD8 cytotoxic T cells for use in cancer immunotherapy

One of the current difficulties limiting the use of adoptive cell therapy (ACT) for cancer treatment is the lack of methods for rapidly expanding T cells. As described in the present report, we developed a centrifugal bioreactor (CBR) that may resolve this manufacturing bottleneck. The CBR operates in perfusion by balancing centrifugal forces with a continuous feed of fresh medium, preventing cells from leaving the expansion culture chamber while maintaining nutrients for growth. A bovine CD8 cytotoxic T lymphocyte (CTL) cell line specific for an autologous target cell infected with a protozoan parasite, Theileria parva, was used to determine the efficacy of the CBR for ACT purposes. Batch culture experiments were conducted to predict how CTLs respond to environmental changes associated with consumption of nutrients and production of toxic metabolites, such as ammonium and lactate. Data from these studies were used to develop a kinetic growth model, allowing us to predict CTL growth in the CBR and determine the optimal operating parameters. The model predicts the maximum cell density the CBR can sustain is 5.5 × 107  cells/mL in a single 11-mL conical chamber with oxygen being the limiting factor. Experimental results expanding CTLs in the CBR are in 95% agreement with the kinetic model. The prototype CBR described in this report can be used to develop a CBR for use in cancer immunotherapy.

Crosstalk between autophagy and metabolic regulation of (CAR) T cells: therapeutic implications

Despite chimeric antigen receptor (CAR) T cell therapy's extraordinary success in subsets of B-cell lymphoma and leukemia, various barriers restrict its application in solid tumors. This has prompted investigating new approaches for producing CAR T cells with superior therapeutic potential. Emerging insights into the barriers to CAR T cell clinical success indicate that autophagy shapes the immune response via reprogramming cellular metabolism and vice versa. Autophagy, a self-cannibalization process that includes destroying and recycling intracellular components in the lysosome, influences T cell biology, including development, survival, memory formation, and cellular metabolism. In this review, we will emphasize the critical role of autophagy in regulating and rewiring metabolic circuits in CAR T cells, as well as how the metabolic status of CAR T cells and the tumor microenvironment (TME) alter autophagy regulation in CAR T cells to restore functional competence in CAR Ts traversing solid TMEs.

Single-Cell RNA and ATAC Sequencing Reveal Hemodialysis-Related Immune Dysregulation of Circulating Immune Cell Subpopulations

Background

An increased risk of infection, malignancy, and cardiovascular diseases in maintenance hemodialysis patients is associated with hemodialysis-related immunity disturbances. Although defects in T-lymphocyte-dependent immune responses and preactivation of antigen-presenting cells have been documented in hemodialysis patients, the effects of long-term hemodialysis on the transcriptional program and chromosomal accessibility of circulating immune cell subpopulations remain poorly defined.

Methods

We integrated single-cell RNA sequencing (scRNA-seq) and single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq) to characterize the transcriptome profiles of peripheral mononuclear cells (PBMCs) from healthy controls and maintenance hemodialysis patients. Validation of differentially expressed genes in CD4+ T cells and monocytes were performed by magnetic bead separation and quantitative real-time PCR.

Results

We identified 16 and 15 PBMC subgroups in scRNA-seq and scATAC-seq datasets, respectively. Hemodialysis significantly suppressed the expression levels of T cell receptor (TCR) genes in CD4+ T cell subsets (e.g., TRAV4, CD45, CD3G, CD3D, CD3E) and major histocompatibility complex II (MHC-II) pathway-related genes in monocytes (HLA-DRB1, HLA-DQA2, HLA-DQA1, HLA-DPB1). Downstream pathways of TCR signaling, including PI3K-Akt-mTOR, MAPK, TNF, and NF-κB pathways, were also inhibited in CD4+ T cell subpopulations during the hemodialysis procedure. Hemodialysis altered cellular communication patterns between PBMC subgroups, particularly TGF-TGFBR, HVEM-BTLA, and IL16-CD4 signalings between CD4+ T cells and monocytes. Additionally, we found that hemodialysis inhibited the expression of AP-1 family transcription factors (JUN, JUND, FOS, FOSB) by interfering with the chromatin accessibility profile.

Conclusions

Our study provides a valuable framework for future investigations of hemodialysis-related immune dysregulation and identifies potential therapeutic targets for reconstituting the circulating immune system in maintenance hemodialysis patients.

The anti-apoptotic and anti-autophagic effects of EPO through PI3K/Akt/mTOR signaling pathway in MAC-T cells

Lipopolysaccharide (LPS) is an important inflammatory and infected factor of bacterial mastitis, which treated bovine mammary epithelial cells (MAC-T) in our previous studies, as mastitis cells model in vitro. Erythropoietin (EPO) is a well-known hematopoietic hormone with antioxidative, anti-apoptotic, and anti-inflammatory roles. We hypothesized that EPO might regulate the apoptosis and autophagy to attenuate the inflammation of mastitis. Western blot, RT-PCR, transmission electron microscope analysis and Annexin V-FITC/PI were used to evaluate the regulation of EPO on apoptosis and autophagy in inflammatory MAC-T cells. These results demonstrated that EPO promoted the proliferation of MAC-T cells. Meanwhile, EPO had a better anti-inflammatory effect in MAC-T cells with LPS treatment. Certainly, EPO also showed anti-apoptotic and anti-autophagic effects. Interestingly, we found that the beneficial effect of EPO on inflammatory MAC-T cells depended on the PI3K/Akt/mTOR signaling pathway, which was involved in the regulation of apoptosis and autophagy. Generally, this study provides an insight for EPO to inhibit apoptosis and autophagy of inflammatory MAC-T cells via PI3K/Akt/mTOR signaling pathway.

Complex molecular mechanism of ammonia-induced apoptosis in chicken peripheral blood lymphocytes: miR-27b-3p, heat shock proteins, immunosuppression, death receptor pathway, and mitochondrial pathway

Ammonia gas, a toxic environmental pollutant, is a vital component of PM2.5 aerosols, and can decrease human and animal immunity. Peripheral blood lymphocytes (PBLs) are main immune cells. Nevertheless, poisoning mechanism of PBLs under ammonia exposure remains unclear. Here, we established an ammonia poisoning model of chicken PBLs to explore poisoning mechanism of ammonia-caused apoptosis in chicken PBLs. Cell viability and apoptosis rate were detected using CCK8 assay and flow cytometry, respectively. Mitochondrial membrane potential (MMP) was observed using fluorescent staining. In addition, qRT-PCR was performed to measure mRNA levels of apoptosis-related genes (tumor necrosis factor-α (TNF-α), tumor necrosis factor receptor 1 (TNFR1), TNF receptor-associated death domain (TRADD), Fas-associated death domain (FADD), Caspase-8, BH3-interacting domain death agonist (Bid), Bcl-2-associated X protein (Bax), Bcl-2 homologous antagonist/killer (Bak), B-cell lymphoma-2 (Bcl-2), Cytochrome-c (Cytc), apoptotic protease activating factor-1 (APAF1), Caspase-9, and Caspase-3), immune-related genes (interferon-γ (IFN-γ), interleukin-2 (IL-2), IL-4, IL-6, IL-1β, IL-10, transforming growth factor-β1 (TGF-β1), IL-17, IL-21, and IL-22), heat shock protein (HSP) genes (HSP25, HSP40, HSP60, HSP70, HSP90, and HSP110), as well as miR-27b-3p. Western blot was used to determine protein levels of apoptosis-related factors (TNF-α, Caspase-8, Bcl-2, Caspase-9, and Caspase-3), as well as HSPs (HSP40, HSP60, HSP70, and HSP90). The results indicated that TRADD, FADD, and APAF1 were target genes of miR-27b-3p, as well as miR-27b-3p participated in molecular mechanism of apoptosis through targeting TNF-α/TNFR1/Caspase-8 death receptor pathway-triggered Bid/Cytc/Caspase-9 mitochondrial pathway in ammonia-treated chicken PBLs. In addition, our findings demonstrated that excess ammonia led to immunosuppression via Th1/Th2 imbalance and Treg/Th17 imbalance. Simultaneously, ammonia stress activated HSPs. In summary, for the first time, our data demonstrated that HSPs-triggered immunosuppression led to apoptosis under ammonia exposure. Our findings provided a new insight into molecular mechanism of ammonia poisoning and an important reference for environmental risk assessment related to ammonia.

Evaluation of potential cardiotoxicity of ammonia: l-selenomethionine inhibits ammonia-induced cardiac autophagy by activating the PI3K/AKT/mTOR signaling pathway

Ammonia is a major harmful gas in the environment of livestock and poultry. Studies have shown that excessive ammonia inhalation has adverse effects in pig heart. However, the mechanism of ammonia-induced cardiac toxicity in pigs has not been reported. L-selenomethionine is a kind of organic selenium (Se) which is easily absorbed by the body. Therefore, in this study, twenty-four 125-day-old pigs were randomly divided into 4 groups: C (control) group, A (ammonia) group, Se group (Se content: 0.5 mg kg-1), and A (ammonia) + Se group. The mechanism of ammonia-induced cardiotoxicity and the alleviating effect of L-selenomethionine were examined. The results in the A group showed as follows: a large number of myocardial fiber edema and cytoplasmic bleakness were observed in the heart; a large number of mitochondrial autophagy were observed; ATP content, ATPase activities and hematological parameters decreased significantly; Endoplasmic reticulum stress (ERS) markers (GRP78, IRE1α, ATF4, ATF6, and CHOP) were significantly induced in the mRNA and protein levels; PI3K/AKT/mTOR signaling pathway was activated; and autophagy key genes and proteins (Beclin-1, LC3, ATG3, and ATG5) were significantly up-regulated. The results of comparison between the A + Se group and the A group were as follows: the degree of edema of cardiac muscle fiber in the A + Se group was somewhat relieved; the level of mitochondrial autophagy decreased; ATP content and ATPase activities increased significantly; the mRNA and protein levels of ERS markers were significantly down-regulated; the expression level of PI3K/AKT/mTOR signaling pathway was decreased; and the mRNA and protein levels of key autophagy genes were decreased. However, the changes of these indexes in the A + Se group were still significantly different from those in the C group. Our results indicated that L-selenomethionine supplementation inhibited ammonia-induced cardiac autophagy by activating the PI3K/AKT/mTOR signaling pathway, which confirmed that L-selenomethionine could alleviate the cardiac injury caused by excessive ammonia inhalation to a certain extent. This study aims to enrich the toxicological mechanism of ammonia and provide valuable reference for future intervention of ammonia toxicity.

Effects of quercetin on tenderness, apoptotic and autophagy signalling in chickens during post-mortem ageing

The effect of quercetin on chicken breast muscle tenderness and the associated mechanism were investigated. The results indicated that quercetin significantly decreased the shear force and increased the myofibril fragmentation index (MFI). Haematoxylin-eosin-stained images showed that the internal structure of myofibril bundles in the quercetin-treated group was obviously degraded. Transmission electron microscopy showed that the myofibril structure, especially the M-line and A-band, was seriously degraded after quercetin treatment. Furthermore, quercetin treatment increased caspase-3 activity and the Bax/Bcl-2 ratio. The intensity of BiP, XBP1 and p-IRE1/IRE1 ratio increased significantly, and caspase-12 was activated. In addition, quercetin induced the transition from LC3I to LC3II and increased the expression of ATG7 and Beclin-1. The PI3K/Akt/mTOR signalling pathway was involved in the induction of autophagy and apoptosis by quercetin. These results indicated quercetin can promote meat tenderization, and activate apoptosis and autophagy pathways during post-mortem ageing.

Autophagy in cancer: The cornerstone during glutamine deprivation

Over the past two decades, researchers have revealed the crucial functions of glutamine in supporting the hyperproliferation state of cancer cells. Glutamine acts on maintaining high energy production, supporting redox status and amino acid homeostasis. Therefore, cancer cells exhibit excessive uptake of the extracellular glutamine, synthesize it in some cases, and recycle intracellular and extracellular proteins to provide an additional source of glutamine to satisfy the increasing glutamine demand. On the other hand, autophagy's role is still debated regarding tumor initiation and progression. However, most cancer cells urgently need autophagy to overcome the existential threats during glutamine restriction stress. Downstream to various stress pathways induced during such a condition, autophagy is considered an indispensable cytoprotective tool to maintain cell integrity and survival. However, the overactivation of the autophagy process is related to lethal consequences. This review summarized glutamine pathways to control autophagy and highlighted autophagy's primary activation pathways, and discussed the roles during glutamine deprivation.

PI3K/AKT/p53 pathway inhibits infectious spleen and kidney necrosis virus infection by regulating autophagy and immune responses

The PI3K/AKT/p53 signaling pathway is activated by various types of cellular stimuli or pathogenic infection, and then regulates fundamental cellular functions to combat these stimulations. Here, we studied the meaningful roles of PI3K/AKT/p53 in regulating cellular machine such as autophagy, immune responses, as well as antiviral activity in Chinese perch brain (CPB) cells infected by infectious spleen and kidney necrosis virus (ISKNV), which is an agent caused devastating losses in mandarin fish (Siniperca chuatsi) industry. We found that ISKNV infection induced up-regulation of host PI3K/AKT/p53 axis, but inhibited autophagy in CPB cells. Interestingly, activation of PI3K/AKT/p53 axis factors trough agonists or overexpression dramatically decreased host autophagy level, inhibited ISKNV replication, and elevated the expression of immune-related genes in CPB cells. In contrast, suppression of PI3K/AKT/p53 pathway by inhibitors or small interfering RNA (siRNA)-mediated gene silence increased the autophagy and ISKNV replication, but down-regulated immune responses in CPB cells. All these results indicate that PI3K/AKT/p53 pathway plays an important role in anti-ISKNV infection and can be used as a new target for controlling ISKNV disease.