TLR7 Stimulation With Imiquimod Induces Selective Autophagy and Controls Mycobacterium tuberculosis Growth in Mouse Macrophages

3,3',4,4'-tetrachlorobiphenyl (PCB77) enhances human Kv1.3 channel currents and alters cytokine production

Polychlorinated biphenyls (PCBs) were once used throughout various industries; however, because of their persistence in the environment, exposure remains a global threat to the environment and human health. The Kv1.3 and Kv1.5 channels have been implicated in the immunotoxicity and cardiotoxicity of PCBs, respectively. We determined whether 3,3',4,4'-tetrachlorobiphenyl (PCB77), a dioxin-like PCB, alters human Kv1.3 and Kv1.5 currents using the Xenopus oocyte expression system. Exposure to 10 nM PCB77 for 15 min enhanced the Kv1.3 current by approximately 30.6%, whereas PCB77 did not affect the Kv1.5 current at concentrations up to 10 nM. This increase in the Kv1.3 current was associated with slower activation and inactivation kinetics as well as right-shifting of the steady-state activation curve. Pretreatment with PCB77 significantly suppressed tumor necrosis factor-α and interleukin-10 production in lipopolysaccharide-stimulated Raw264.7 macrophages. Overall, these data suggest that acute exposure to trace concentrations of PCB77 impairs immune function, possibly by enhancing Kv1.3 currents.

The tRNAVal half: A strong endogenous Toll-like receptor 7 ligand with a 5'-terminal universal sequence signature

Toll-like receptors (TLRs) are crucial components of the innate immune system. Endosomal TLR7 recognizes single-stranded RNAs, yet its endogenous ssRNA ligands are not fully understood. We previously showed that extracellular (ex-) 5'-half molecules of tRNAHisGUG (the 5'-tRNAHisGUG half) in extracellular vesicles (EVs) of human macrophages activate TLR7 when delivered into endosomes of recipient macrophages. Here, we fully explored immunostimulatory ex-5'-tRNA half molecules and identified the 5'-tRNAValCAC/AAC half, the most abundant tRNA-derived RNA in macrophage EVs, as another 5'-tRNA half molecule with strong TLR7 activation capacity. Levels of the ex-5'-tRNAValCAC/AAC half were highly up-regulated in macrophage EVs upon exposure to lipopolysaccharide and in the plasma of patients infected with Mycobacterium tuberculosis. The 5'-tRNAValCAC/AAC half-mediated activation of TLR7 effectively eradicated bacteria infected in macrophages. Mutation analyses of the 5'-tRNAValCAC/AAC half identified the terminal GUUU sequence as a determinant for TLR7 activation. We confirmed that GUUU is the optimal ratio of guanosine and uridine for TLR7 activation; microRNAs or other RNAs with the terminal GUUU motif can indeed stimulate TLR7, establishing the motif as a universal signature for TLR7 activation. These results advance our understanding of endogenous ssRNA ligands of TLR7 and offer insights into diverse TLR7-involved pathologies and their therapeutic strategies.

Recognition of Mycobacterium tuberculosis by macrophage Toll-like receptor and its role in autophagy

BACKGROUND

The pathogen responsible for tuberculosis is called Mycobacterium tuberculosis. Its interaction with macrophages has a significant impact on the onset and progression of the disease.

METHODS

The respiratory pathway allows Mycobacterium tuberculosis to enter the body's lungs where it battles immune cells before being infected latently or actively. In the progress of tuberculosis, Mycobacterium tuberculosis activates the body's immune system and creates inflammatory factors, which cause tissue inflammation to infiltrate and the creation of granulomas, which seriously harms the body. Toll-like receptors of macrophage can mediate host recognition of Mycobacterium tuberculosis, initiate immune responses, and participate in macrophage autophagy. New host-directed therapeutic approaches targeting autophagy for drug-resistant Mycobacterium tuberculosis have emerged, providing new ideas for the effective treatment of tuberculosis.

CONCLUSIONS

In-depth understanding of the mechanisms by which macrophage autophagy interacts with intracellular Mycobacterium tuberculosis, as well as the study of potent and specific autophagy-regulating molecules, will lead to much-needed advances in drug discovery and vaccine design, which will improve the prevention and treatment of human tuberculosis.

Immunostimulatory short non-coding RNAs in the circulation of patients with tuberculosis infection

Mycobacterium tuberculosis (Mtb) infection is among the world's deadliest infectious diseases. Developing effective treatments and biomarkers for tuberculosis requires a deeper understanding of its pathobiology and host responses. Here, we report a comprehensive characterization of circulating short non-coding RNAs (sncRNAs) in plasma samples from Mtb-infected patients. We achieved this by pre-treating plasma RNAs with T4 polynucleotide kinase to convert all RNA ends to those compatible with sncRNA sequencing. We discovered a global and drastic upregulation of plasma sncRNAs in Mtb-infected patients, with tRNA-derived sncRNAs representing the most dramatically elevated class. Most of these tRNA-derived sncRNAs originated from a limited subset of tRNAs, specifically from three tRNA isoacceptors, and exhibited skewed patterns to 5'-derived fragments, such as 5' halves, 5' tRNA fragments (tRFs), and internal tRFs (i-tRFs) from the 5' regions. Further, Mtb-infected patients displayed markedly upregulated and distinct profiles of both rRNA- and mRNA-derived sncRNAs. Some of these sncRNAs, which are abundant and specific to Mtb-infected patients, robustly activated human macrophages via Toll-like receptor 7 and induced cytokine production. This drastic accumulation of circulating, immunostimulatory sncRNAs in the plasma of Mtb-infected patients offers insights into the sncRNA-driven aspects of host immune response against infectious diseases and suggests a pool of potential therapeutic targets and biomarkers.

Activation of host nucleic acid sensors by Mycobacterium: good for us or good for them?

Although the importance of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) sensors in controlling viral infection is well established, their role in promoting an effective immune response to pathogens other than viruses is less clear. This is particularly true for infections with mycobacteria, as studies point to both protective and detrimental roles for activation of nucleic acid sensors in controlling a mycobacterial infection. Some of the contradiction likely stems from the use of different model systems and different mycobacterial species/strains as well as from which nucleic acid sensors were studied and what downstream effectors were evaluated. In this review, we will describe the different nucleic acid sensors that have been studied in the context of mycobacterial infections, and how the different studies compare. We conclude with a section on how nucleic acid sensor agonists have been used therapeutically and what further information is needed to enhance their potential as therapeutic agents.

Mycobacterium tuberculosis: Pathogenesis and therapeutic targets

Tuberculosis (TB) remains a significant public health concern in the 21st century, especially due to drug resistance, coinfection with diseases like immunodeficiency syndrome (AIDS) and coronavirus disease 2019, and the lengthy and costly treatment protocols. In this review, we summarize the pathogenesis of TB infection, therapeutic targets, and corresponding modulators, including first-line medications, current clinical trial drugs and molecules in preclinical assessment. Understanding the mechanisms of Mycobacterium tuberculosis (Mtb) infection and important biological targets can lead to innovative treatments. While most antitubercular agents target pathogen-related processes, host-directed therapy (HDT) modalities addressing immune defense, survival mechanisms, and immunopathology also hold promise. Mtb's adaptation to the human host involves manipulating host cellular mechanisms, and HDT aims to disrupt this manipulation to enhance treatment effectiveness. Our review provides valuable insights for future anti-TB drug development efforts.

The interaction between autophagy, Helicobacter pylori, and gut microbiota in gastric carcinogenesis

Chronic infection with Helicobacter pylori is the primary risk factor for the development of gastric cancer. Hindering our ability to comprehend the precise role of autophagy during H. pylori infection is the complexity of context-dependent autophagy signaling pathways. Recent and ongoing progress in understanding H. pylori virulence allows new frontiers of research for the crosstalk between autophagy and H. pylori. Novel approaches toward discovering autophagy signaling networks have further revealed their critical influence on the structure of gut microbiota and the metabolome. Here we intend to present a holistic view of the perplexing role of autophagy in H. pylori pathogenesis and carcinogenesis. We also discuss the intermediate role of autophagy in H. pylori-mediated modification of gut inflammatory responses and microbiota structure.

Keratinoctye-neuro-immune-units (KNICUs): collaborative impact on the initiation and maintenance of psoriasis

The skin is the outermost barrier that separates the human body from the external environment. In psoriasis, immune cells reside within or infiltrate the epidermis to form the epidermal (epithelial) immunological microenvironment (EIME) and engage in complex interactions with keratinocytes, nerves, and microbiota. The proposed hypothesis is that psoriasis is a chronic inflammatory disease mainly mediated by a specific inflammatory environment composed of keratinocyte-neuro-immune cell units (KNICUs). These KNICUs arise from the interaction between activated epidermal keratinocytes, nerves, immune cells, and the skin microbiota, forming a complex interaction framework. Multiple units gather to complete the circulatory and amplified loops, consequently serving as a group army to initiate and maintain psoriasis.

Activation of TLR7-mediated autophagy increases epileptic susceptibility via reduced KIF5A-dependent GABAA receptor transport in a murine model

The pathophysiological mechanisms underlying epileptogenesis are poorly understood but are considered to actively involve an imbalance between excitatory and inhibitory synaptic transmission. Excessive activation of autophagy, a cellular pathway that leads to the removal of proteins, is known to aggravate the disease. Toll-like receptor (TLR) 7 is an innate immune receptor that regulates autophagy in infectious and noninfectious diseases. However, the relationship between TLR7, autophagy, and synaptic transmission during epileptogenesis remains unclear. We found that TLR7 was activated in neurons in the early stage of epileptogenesis. TLR7 knockout significantly suppressed seizure susceptibility and neuronal excitability. Furthermore, activation of TLR7 induced autophagy and decreased the expression of kinesin family member 5 A (KIF5A), which influenced interactions with γ-aminobutyric acid type A receptor (GABAAR)-associated protein and GABAARβ2/3, thus producing abnormal GABAAR-mediated postsynaptic transmission. Our results indicated that TLR7 is an important factor in regulating epileptogenesis, suggesting a possible therapeutic target for epilepsy.

Long-Term Immunogenicity and In Vitro Prophylactic Protective Efficacy of M. tuberculosis Fusion Protein DR2 Combined with Liposomal Adjuvant DIMQ as a Boosting Vaccine for BCG

The resuscitation of dormant Mycobacterium tuberculosis is an important cause of adult tuberculosis (TB) transmission. According to the interaction mechanism between M. tuberculosis and the host, the latency antigen Rv0572c and region of difference 9 (RD9) antigen Rv3621c were selected in this study to prepare the fusion protein DR2. Stimulating clinically diagnosed active tuberculosis infections (i.e., TB patients), latent tuberculosis infections, and healthy controls confirmed that T lymphocytes could recognize DR2 protein in the peripheral blood of TB-infected individuals more than subcomponent protein. The DR2 protein was then emulsified in the liposome adjuvant dimethyl dioctadecyl ammonium bromide, and imiquimod (DIMQ) was administered to C57BL/6 mice immunized with Bacillus Calmette-Guérin (BCG) vaccine to evaluate their immunogenicity. Studies have shown that DR2/DIMQ, a booster vaccine for BCG primary immunization, can elicit robust CD4⁺ Th1 cell immune response and predominant IFN-γ⁺ CD4⁺ effector memory T cells (T_EM) subsets. Furthermore, the serum antibody level and the expression of related cytokines increased significantly with the extension of immunization time, with IL2⁺, CD4⁺, or CD8⁺ central memory T cells (T_CM) subsets predominant in the long term. This immunization strategy showed matched prophylactic protective efficacy by performing in vitro challenge experiment. This result provides robust evidence that the novel subunit vaccine prepared by fusion protein DR2 combined with liposomal adjuvant DIMQ is a promising TB vaccine candidate for further preclinical trials as a booster vaccine for BCG.

Mycobacterium tuberculosis Rv0790c inhibits the cellular autophagy at its early stage and facilitates mycobacterial survival

Rv0790c is predicted to be a conserved hypothetical protein encoded by Mycobacterium tuberculosis (Mtb). However, its function in Mtb infection remains largely unknown. In this study, we found that Rv0790c promoted bacillary survival of M. smegmatis (Ms), both in vitro and in vivo. The bacillary burden of Ms exogenously expressing Rv0790c increased, whereas in Rv0790c-knockouts the bacillary burden decreased in infected macrophages. Multiple cellular processes were analyzed to explore the underlying mechanisms. We found that neither inflammatory regulation nor apoptotic induction were responsible for the promotion of bacillary survival mediated by Rv0790c. Interestingly, we found that Rv0790c facilitates mycobacterial survival through cellular autophagy at its early stage. Immunoprecipitation assay of autophagy initiation-related proteins indicated that Rv0790c interacted with mTOR and enhanced its activity, as evidenced by the increased phosphorylation level of mTOR downstream substrates, ULK-1, at Ser757 and P70S6K, at Thr389. Our study uncovers a novel autophagy suppressor encoded by mycobacterial Rv0790c, which inhibits the early stage of cellular autophagy induction upon Mtb infection and takes an important role in maintaining intracellular mycobacterial survival. It may aid in understanding the mechanism of Mtb evasion of host cellular degradation, as well as hold the potential to develop new targets for the prevention and treatment of tuberculosis.

Host-Directed Therapies for Tuberculosis

Tuberculosis (TB) is one of the leading causes of death worldwide, consistently threatening public health. Conventional tuberculosis treatment requires a long-term treatment regimen and is associated with side effects. The efficacy of antitubercular drugs has decreased with the emergence of drug-resistant TB; therefore, the development of new TB treatment strategies is urgently needed. In this context, we present host-directed therapy (HDT) as an alternative to current tuberculosis therapy. Unlike antitubercular drugs that directly target Mycobacterium tuberculosis (Mtb), the causative agent of TB, HDT is an approach for treating TB that appropriately modulates host immune responses. HDT primarily aims to enhance the antimicrobial activity of the host in order to control Mtb infection and attenuate excessive inflammation in order to minimize tissue damage. Recently, research based on the repositioning of drugs for use in HDT has been in progress. Based on the overall immune responses against Mtb infection and the immune-evasion mechanisms of Mtb, this review examines the repositioned drugs available for HDT and their mechanisms of action.

Corilagin Restrains NLRP3 Inflammasome Activation and Pyroptosis through the ROS/TXNIP/NLRP3 Pathway to Prevent Inflammation

Corilagin, a gallotannin, shows excellent antioxidant and anti-inflammatory effects. The NLRP3 inflammasome dysfunction has been implicated in a variety of inflammation diseases. However, it remains unclear how corilagin regulates the NLRP3 inflammasome to relieve gouty arthritis. In this study, bone marrow-derived macrophages (BMDMs) were pretreated with lipopolysaccharide (LPS) and then incubated with NLRP3 inflammasome agonists, such as adenine nucleoside triphosphate (ATP), nigericin, and monosodium urate (MSU) crystals. The MSU crystals were intra-articular injected to induce acute gouty arthritis. Here we showed that corilagin reduced lactate dehydrogenase (LDH) secretion and the proportion of propidium iodide- (PI-)stained cells. Corilagin suppressed the expression of N-terminal of the pyroptosis executive protein gasdermin D (GSDMD-NT). Corilagin restricted caspase-1 p20 and interleukin (IL)-1β release. Meanwhile, corilagin attenuated ASC oligomerization and speck formation. Our findings confirmed that corilagin diminished NLRP3 inflammasome activation and macrophage pyroptosis. We further discovered that corilagin limited the mitochondrial reactive oxygen species (ROS) production and prevented the interaction between TXNIP and NLRP3, but ROS activator imiquimod could antagonize the inhibitory function of corilagin on NLRP3 inflammasome and macrophage pyroptosis. Additionally, corilagin ameliorated MSU crystals induced joint swelling, inhibited IL-1β production, and abated macrophage and neutrophil migration into the joint capsule. Collectively, these results demonstrated that corilagin suppressed the ROS/TXNIP/NLRP3 pathway to repress inflammasome activation and pyroptosis and suggest its potential antioxidative role in alleviating NLRP3-dependent gouty arthritis.

BNIP3 mediates the different adaptive responses of fibroblast-like synovial cells to hypoxia in patients with osteoarthritis and rheumatoid arthritis

Background

Hypoxia is one of the important characteristics of synovial microenvironment in rheumatoid arthritis (RA), and plays an important role in synovial hyperplasia. In terms of cell survival, fibroblast-like synovial cells (FLSs) are relatively affected by hypoxia. In contrast, fibroblast-like synovial cells from patients with RA (RA-FLSs) are particularly resistant to hypoxia-induced cell death. The purpose of this study was to evaluate whether fibroblast-like synovial cells in patients with osteoarthritis (OA-FLSs) and RA-FLSs have the same adaptation to hypoxia.

Methods

CCK-8, flow cytometry and BrdU were used to detect the proliferation of OA-FLSs and RA-FLSs under different oxygen concentrations. Apoptosis was detected by AV/PI, TUNEL and Western blot, mitophagy was observed by electron microscope, laser confocal microscope and Western blot, the state of mitochondria was detected by ROS and mitochondrial membrane potential by flow cytometry, BNIP3 and HIF-1α were detected by Western blot and RT-qPCR. The silencing of BNIP3 was achieved by stealth RNA system technology.

Results

After hypoxia, the survival rate of OA-FLSs decreased, while the proliferation activity of RA-FLSs further increased. Hypoxia induced an increase in apoptosis and inhibition of mitophagy in OA-FLSs, but not in RA-FLSs. Hypoxia led to a more lasting adaptive response. RA-FLSs displayed a more significant increase in the expression of genes transcriptionally regulated by HIF-1α. Interestingly, they showed higher BNIP3 expression than OA-FLSs, and showed stronger mitophagy and proliferation activities. BNIP3 siRNA experiment confirmed the potential role of BNIP3 in the survival of RA-FLSs. Inhibition of BNIP3 resulted in the decrease of cell proliferation, mitophagy and the increase of apoptosis.

Conclusion

In summary, RA-FLSs maintained intracellular redox balance through mitophagy to promote cell survival under hypoxia. The mitophagy of OA-FLSs was too little to maintain the redox balance of mitochondria, resulting in apoptosis. The difference of mitophagy between OA-FLSs and RA-FLSs under hypoxia is mediated by the level of BNIP3 expression.

Identification of Potential Diagnoses Based on Immune Infiltration and Autophagy Characteristics in Major Depressive Disorder

Background: Major depressive disorder (MDD) is a serious mental illness characterized by mood changes and high suicide rates. However, no studies are available to support a blood test method for MDD diagnosis. The objective of this research was to identify potential peripheral blood biomarkers for MDD and characterize the novel pathophysiology.

Methods: We accessed whole blood microarray sequencing data for MDD and control samples from public databases. Biological functions were analysed by GO and KEGG pathway enrichment analyses using the clusterprofile R package. Infiltrated immune cell (IIC) proportions were identified using the CIBERSORT algorithm. Clustering was performed using the ConsensusClusterPlus R package. Protein–protein interactions (PPI) were assessed by constructing a PPI network using STRING and visualized using Cytoscape software. Rats were exposed to chronic unpredictable mild stress (CUMS) for 6 weeks to induce stress behaviour. Stress behaviour was evaluated by open field experiments and forced swimming tests. Flow cytometry was used to analyse the proportion of CD8⁺ T cells. The expression of the corresponding key genes was detected by qRT–PCR.

Results: We divided MDD patients into CD8H and CD8L clusters. The functional enrichment of marker genes in the CD8H cluster indicated that autophagy-related terms and pathways were significantly enriched. Furthermore, we obtained 110 autophagy-related marker genes (ARMGs) in the CD8H cluster through intersection analysis. GO and KEGG analyses further showed that these ARMGs may regulate a variety of autophagy processes and be involved in the onset and advancement of MDD. Finally, 10 key ARMGs were identified through PPI analysis: RAB1A, GNAI3, VAMP7, RAB33B, MYC, LAMP2, RAB11A, HIF1A, KIF5B, and PTEN. In the CUMS model, flow cytometric analysis confirmed the above findings. qRT–PCR revealed significant decreases in the mRNA levels of Gnai3, Rab33b, Lamp2, and Kif5b in the CUMS groups.

Conclusion: In this study, MDD was divided into two subtypes. We combined immune infiltrating CD8⁺ T cells with autophagy-related genes and screened a total of 10 ARMG genes. In particular, RAB1A, GNAI3, RAB33B, LAMP2, and KIF5B were first reported in MDD. These genes may offer new hope for the clinical diagnosis of MDD.

Stimulation of Toll-Like Receptor 3 Diminishes Intracellular Growth of Salmonella Typhimurium by Enhancing Autophagy in Murine Macrophages

The Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative Gram-negative bacterium that causes acute gastroenteritis and food poisoning. S. Typhimurium can survive within macrophages that are able to initiate the innate immune response after recognizing bacteria via various pattern-recognition receptors (PRRs), such as Toll-like receptors (TLRs). In this study, we investigated the effects and molecular mechanisms by which agonists of endosomal TLRs—especially TLR3—contribute to controlling S. Typhimurium infection in murine macrophages. Treatment with polyinosinic:polycytidylic acid (poly(I:C))—an agonist of TLR3—significantly suppressed intracellular bacterial growth by promoting intracellular ROS production in S. Typhimurium-infected cells. Pretreatment with diphenyleneiodonium (DPI)—an NADPH oxidase inhibitor—reduced phosphorylated MEK1/2 levels and restored intracellular bacterial growth in poly(I:C)-treated cells during S. Typhimurium infection. Nitric oxide (NO) production increased through the NF-κB-mediated signaling pathway in poly(I:C)-treated cells during S. Typhimurium infection. Intracellular microtubule-associated protein 1A/1B-light chain 3 (LC3) levels were increased in poly(I:C)-treated cells; however, they were decreased in cells pretreated with 3-methyladenine (3-MA)—a commonly used inhibitor of autophagy. These results suggest that poly(I:C) induces autophagy and enhances ROS production via MEK1/2-mediated signaling to suppress intracellular bacterial growth in S. Typhimurium-infected murine macrophages, and that a TLR3 agonist could be developed as an immune enhancer to protect against S. Typhimurium infection.

The Advancing of Selenium Nanoparticles Against Infectious Diseases

Infectious diseases, caused by the direct exposure of cellular or acellular pathogens, are found to be closely associated with multiple inflammation and immune responses, keeping one of the top threats to human health. As an indispensable trace element, Selenium (Se) plays important roles in antioxidant defence and redox state regulation along with a variety of specific metabolic pathways. In recent decades, with the development of novel nanotechnology, Selenium nanoparticles (Se NPs) emerged as a promising agent for biomedical uses due to their low toxicity, degradability and high bioavailability. Taking the advantages of the strong ability to trigger apoptosis or autophagy by regulating reactive oxygen species (ROS), Se NPs have been widely used for direct anticancer treatments and pathogen killing/clearance in host cells. With excellent stability and drug encapsulation capacity, Se NPs are now serving as a kind of powerful nano-carriers for anti-cancer, anti-inflammation and anti-infection treatments. Notably, Se NPs are also found to play critical roles in immunity regulations, such as macrophage and T effector cell activation, which thus provides new possibilities to achieve novel nano-immune synergetic strategy for anti-cancer and anti-infection therapies. In this review, we summarized the progress of preparation methods for Se NPs, followed by the advances of their biological functions and mechanisms for biomedical uses, especially in the field of anti-infection treatments. Moreover, we further provide some prospects of Se NPs in anti-infectious diseases, which would be helpful for facilitating their future research progress for anti-infection therapy.

Autophagy Induction as a Host-Directed Therapeutic Strategy against Mycobacterium tuberculosis Infection

Tuberculosis (TB), a bacterialinfectious disease caused by Mycobacterium tuberculosis (M.tb), which causes significant mortality in humans worldwide. Current treatment regimen involve the administration of multiple antibiotics over the course of several months that contributes to patient non-compliance leading to relapse and the development of drug-resistant M.tb (MDR and XDR) strains. Together, these facts highlight the need for the development of shorter TB treatment regimens. Host-directed therapy (HDT) is a new and emerging concept that aims to augment host immune response using drugs/compounds with or without adjunct antibiotics against M.tb infection. Autophagy is a natural catabolic mechanism of the cell that involves delivering the cytosolic constituents to the lysosomes for degradation and recycling the components; thereby maintaining the cellular and energy homoeostasis of a cell. However, over the past decade, an improved understanding of the role of autophagy in immunity has led to autophagy activation by using drugs or agents. This autophagy manipulation may represent a promising host-directed therapeutic strategy for human TB. However, current clinical knowledge on implementing autophagy activation by drugs or agents, as a stand-alone HDT or as an adjunct with antibiotics to treat human TB is insufficient. In recent years, many reports on high-throughput drug screening and measurement of autophagic flux by fluorescence, high-content microscopy, flow cytometry, microplate reader and immunoblotting have been published for the discovery of drugs that modulate autophagy. In this review, we discuss the commonly used chemical screening approaches in mammalian cells for the discovery of autophagy activating drugs against M.tbinfection. We also summarize the various autophagy-activating agents, both pre-clinical candidates and compounds approved for advanced clinical investigation during mycobacterial infection. Finally, we discuss the opportunities and challenges in using autophagy activation as HDT strategy to improve TB outcome and shorten treatment regimen.

Rapamycin Promotes ROS-Mediated Cell Death via Functional Inhibition of xCT Expression in Melanoma Under γ-Irradiation

Although many cancer patients are administered radiotherapy for their treatment, the interaction between tumor cells and macrophages in the tumor microenvironment attenuates the curative effects of radiotherapy. The enhanced activation of mTOR signaling in the tumors promotes tumor radioresistance. In this study, the effects of rapamycin on the interaction between tumor cells and macrophages were investigated. Rapamycin and 3BDO were used to regulate the mTOR pathway. In vitro, tumor cells cocultured with macrophages in the presence of each drug under normoxic or hypoxic conditions were irradiated with γ–rays. In vivo, mice were irradiated with γ–radiation after injection with DMSO, rapamycin and 3BDO into tumoral regions. Rapamycin reduced the secretion of IL-4 in tumor cells as well as YM1 in macrophages. Mouse recombinant YM1 decreased the enhanced level of ROS and the colocalized proportion of both xCT and EEA1 in irradiated tumor cells. Human recombinant YKL39 also induced results similar to those of YM1. Moreover, the colocalized proportion of both xCT and LC3 in tumor tissues was elevated by the injection of rapamycin into tumoral regions. Overall, the suppression of mTOR signaling in the tumor microenvironment might be useful for the improvement of tumor radioresistance.