Autophagy in innate and adaptive immunity against intracellular pathogens

Cardiovascular toxicities associated with chimeric antigen receptor T-cell therapy

Chimeric antigen receptor (CAR) T-cell therapy has emerged as a groundbreaking immunotherapeutic approach, particularly for oncohematological patients who are refractory to conventional treatments. As clinical trials expand the applications of CAR T-cell therapy beyond hematologic malignancies, a critical understanding of its associated toxicities, particularly cardiovascular complications, becomes imperative. This review synthesizes current literature on the interplay between cytokine release syndrome (CRS) and cardiotoxicity related to CAR T-cell therapy, emphasizing the potential severity of these adverse events. While significant progress has been made in managing CRS, the cardiac manifestations-ranging from mild events to life-threatening complications-remain underreported in pivotal studies. We explore the incidence and nature of cardiotoxicity in real-world and clinical trial settings, identify risk factors contributing to cardiovascular events, and propose guidelines for pre-therapy evaluations, post-infusion monitoring, and management strategies. By highlighting the urgent need for heightened awareness and proactive care, this review aims to enhance patient safety and optimize outcomes in the evolving landscape of CAR T-cell therapy.

Fabry Disease and Inflammation: Potential Role of p65 iso5, an Isoform of the NF-κB Complex

Fabry disease (FD) is an X-linked lysosomal storage disease, caused by mutations in the GLA gene on the X chromosome, resulting in a deficiency of the lysosomal enzyme α-GAL. This leads to the progressive accumulation of Gb3 in cells, causing multi-systemic effects. FD has been classified as a subgroup of autoinflammatory diseases. NF-κB is a family of ubiquitous and inducible transcription factors that play critical roles in inflammation, in which the p65/p50 heterodimer is the most abundant. The glucocorticoid receptor (GR) represents the physiological antagonists in the inflammation process. A novel spliced variant of p65, named p65 iso5, which can bind the dexamethasone, enhancing GR activity, has been found. This study investigates the potential role of p65 iso5 in the inflammation of subjects with FD. We evaluated in peripheral blood mononuclear cells (PBMCs), from over 100 FD patients, the p65 iso5 mRNA level, and the protein expression. The results showed significantly lower p65 iso5 mRNA and protein expression levels compared to controls. These findings, along with the ability of p65 iso5 to bind dexamethasone and the regulation of the glucocorticoid response in the opposite way of p65, strongly suggest the involvement of p65 iso5 in the inflammatory response in FD.

ANXA4 restricts HBV replication by inhibiting autophagic degradation of MCM2 in chronic hepatitis B

BACKGROUND

Hepatitis B virus (HBV) is an enveloped DNA virus that causes chronic hepatitis B (CHB) infection. Annexin, a Ca2+-activated protein, is widely expressed in various organs and tissues and has potential utility in disease diagnosis and treatment. However, the relationship between the annexin family and CHB remains unclear.

METHODS

Clinical samples from hepatitis patients and donors or healthy individuals were collected. Transcriptome sequencing in CHB liver tissues and HBV-infected cells were performed. HepG2.2.15 cells with the full-length HBV genome and HBV-infected HepG2-NTCP cell models were established. HBV-infected mouse model was constructed and adeno-associated virus was utilized.

RESULTS

ANXA4 expression was elevated during CHB infection. ANXA4 knockdown promoted HBV replication and aggravated liver injury, while ANXA4 overexpression alleviated that. Mechanistically, autophagy pathway was activated by ANXA4 deficiency, promoting autophagic degradation of minichromosome maintenance complex component 2 (MCM2). MCM2 inhibition activated HBV replication, while MCM2 overexpression attenuated ANXA4 deficiency-induced HBV replication and liver injury. Clinically, the expression of hepatitis B viral protein was negatively correlated with the ANXA4 levels, and CHB patients with high ANXA4 levels (> 8 ng/ml) showed higher sensitivity to interferon therapy.

CONCLUSIONS

ANXA4 functions as a protective factor during HBV infection. ANXA4 expression is elevated under HBV attack to restrict HBV replication by inhibiting autophagic degradation of MCM2, thereby alleviating liver injury and suppressing the CHB infection process. ANXA4 also enhances the sensitivity of CHB patients to interferon therapy. Therefore, ANXA4 is expected to be a new target for CHB treatment and prognostic evaluation.

Inflammation in Fabry disease: stages, molecular pathways, and therapeutic implications

Fabry disease, a multisystem X-linked disorder caused by mutations in the alpha-galactosidase gene. This leads to the accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (Lyso-Gb3), culminating in various clinical signs and symptoms that significantly impact quality of life. Although treatments such as enzyme replacement, oral chaperone, and emerging therapies like gene therapy exist; delayed diagnosis often curtails their effectiveness. Our review highlights the importance of delineating the stages of inflammation in Fabry disease to enhance the timing and efficacy of diagnosis and interventions, particularly before the progression to fibrosis, where treatment options are less effective. Inflammation is emerging as an important aspect of the pathogenesis of Fabry disease. This is thought to be predominantly mediated by the innate immune response, with growing evidence pointing towards the potential involvement of adaptive immune mechanisms that remain poorly understood. Highlighted by the fact that Fabry disease shares immune profiles with systemic autoinflammatory diseases, blurring the distinctions between these disorders and highlighting the need for a nuanced understanding of immune dynamics. This insight is crucial for developing targeted therapies and improving the administration of current treatments like enzyme replacement. Moreover, our review discusses the complex interplay between these inflammatory processes and current treatments, such as the challenges posed by anti-drug antibodies. These antibodies can attenuate the effectiveness of therapies, necessitating more refined approaches to mitigate their impact. By advancing our understanding of the molecular changes, inflammatory mediators and causative factors that drive inflammation in Fabry disease, we aim to clarify their role in the disease's progression. This improved understanding will help us see how these processes fit into the current landscape of Fabry disease. Additionally, it will guide the development of more effective diagnostic and therapeutic approaches, ultimately improving patient care.

Arrhythmogenesis in Fabry Disease

PURPOSE OF REVIEW

Fabry Disease (FD) is a rare lysosomal storage disorder characterised by multiorgan accumulation of glycosphingolipid due to deficiency in the enzyme α-galactosidase A. Cardiac sphingolipid accumulation triggers various types of arrhythmias, predominantly ventricular arrhythmia, bradyarrhythmia, and atrial fibrillation. Arrhythmia is likely the primary contributor to FD mortality with sudden cardiac death, the most frequent cardiac mode of death. Traditionally FD was seen as a storage cardiomyopathy triggering left ventricular hypertrophy, diastolic dysfunction, and ultimately, systolic dysfunction in advanced disease. The purpose of this review is to outline the current evidence exploring novel mechanisms underlying the arrhythmia substrate.

RECENT FINDINGS

There is growing evidence that FD cardiomyopathy is a primary arrhythmic disease with each stage of cardiomyopathy (accumulation, hypertrophy, inflammation, and fibrosis) contributing to the arrhythmia substrate via various intracellular, extracellular, and environmental mechanisms. It is therefore important to understand how these mechanisms contribute to an individual's risk of arrhythmia in FD. In this review, we outline the epidemiology of arrhythmia, pathophysiology of arrhythmogenesis, risk stratification, and cardiac therapy in FD. We explore how advances in conventional cardiac investigations performed in FD patients including 12-lead electrocardiography, transthoracic echocardiography, and cardiac magnetic resonance imaging have enabled early detection of pro-arrhythmic substrate. This has allowed for appropriate risk stratification of FD patients. This paves the way for future work exploring the development of therapeutic initiatives and risk prediction models to reduce the burden of arrhythmia.

Exploring and exploiting the host cell autophagy during Mycobacterium tuberculosis infection

Tuberculosis, caused by Mycobacterium tuberculosis, is a fatal infectious disease that prevails to be the second leading cause of death from a single infectious agent despite the availability of multiple drugs for treatment. The current treatment regimen involves the combination of several drugs for 6 months that remain ineffective in completely eradicating the infection because of several drawbacks, such as the long duration of treatment and the side effects of drugs causing non-adherence of patients to the treatment regimen. Autophagy is an intracellular degradative process that eliminates pathogens at the early stages of infection. Mycobacterium tuberculosis's unique autophagy-blocking capability makes it challenging to eliminate compared to usual pathogens. The present review discusses recent advances in autophagy-inhibiting factors and mechanisms that could be exploited to identify autophagy-inducing chemotherapeutics that could be used as adjunctive therapy with the existing first-line anti-TB agent to shorten the duration of therapy and enhance cure rates from multidrug-resistant tuberculosis (MDR-TB) and extreme drug-resistant tuberculosis (XDR-TB).

Infection of epithelioma papulosum cyprini (EPC) cells with spring viremia of carp virus (SVCV) induces autophagy and apoptosis through endoplasmic reticulum stress

Spring viremia of carp virus (SVCV) is a lethal freshwater pathogen of cyprinid fish that has caused significant economic losses to aquaculture. To reduce the economic losses caused by SVCV, its pathogenic mechanism needs to be studied more thoroughly. Here, we report for the first time that SVCV infection of Epithelioma papulosum cyprini (EPC) cells can induce cellular autophagy and apoptosis through endoplasmic reticulum stress. The presence of autophagic vesicles in infected EPC cells was shown by transmission electron microscopy. Quantitative fluorescence PCR and Western blot results showed that p62 mRNA expression was decreased, and the expression of Beclin1 and LC3 mRNA was increased. The p62 protein was decreased, and the Beclin1 protein and LC3 were increased in the endoplasmic reticulum stress activation state. To further clarify the mode of death of SVCV-infected EPC cells, we examined caspase3, caspase9, BCL-2, and Bax mRNA, which showed that they were all increased. Apoptosis of SVCV-infected cells increased upon activation of endoplasmic reticulum stress. Our results suggest that endoplasmic reticulum stress can regulate SVCV infection-induced autophagy and apoptosis. The results of this study provide theoretical data for the pathogenesis of SVCV and lay the foundation for future drug development and vaccine construction.

Paxbp1 is indispensable for the survival of CD4 and CD8 double-positive thymocytes

The lifespan of double-positive (DP) thymocytes is critical for intrathymic development and shaping the peripheral T cell repertoire. However, the molecular mechanisms that control DP thymocyte survival remain poorly understood. Paxbp1 is a conserved nuclear protein that has been reported to play important roles in cell growth and development. Its high expression in T cells suggests a possible role in T cell development. Here, we observed that deletion of Paxbp1 resulted in thymic atrophy in mice lacking Paxbp1 in the early stages of T cell development. Conditional loss of Paxbp1 resulted in fewer CD4+CD8+ DP T cells, CD4 and CD8 single positive (SP) T cells in the thymus, and fewer T cells in the periphery. Meanwhile, Paxbp1 deficiency had limited effects on the CD4-CD8- double negative (DN) or immature single-positive (ISP) cell populations. Instead, we observed a significant increase in the susceptibility of Paxbp1-deficient DP thymocytes to apoptosis. Consistent with this, RNA-Seq analysis revealed a significant enrichment of the apoptotic pathway within differentially expressed genes in Paxbp1-deficient DP cells compared to control DP cells. Together, our results suggest a new function for Paxbp1, which is an important mediator of DP thymocyte survival and critical for proper thymic development.

Autophagy benefits the in vitro and in vivo clearance of Talaromyces marneffei

Talaromycosis, namely Talaromyces marneffei infection, is increasing gradually and has a high mortality rate even under antifungal therapy. Although autophagy acts differently on different pathogens, it is a promising therapeutic strategy. However, information on autophagy in macrophages and animals upon infection by T. marneffei is still limited. Therefore, several models were employed here to investigate the role of autophagy in host defense against T. marneffei, including RAW264.7 macrophages as in vitro models, different types of Caenorhabditis elegans and BALB/c mice as in vivo models. We applied the clinical T. marneffei isolate SUMS0152 in this study. T. marneffei-infected macrophages exhibit increased formation of autophagosomes. Further, macrophage autophagy promoted by rapamycin or Earle's balanced salt solution (EBSS) inhibited the viability of intracellular T. marneffei. In vivo, compared with uninfected Caenorhabditis elegans, the wild-type nematodes upregulated the expression of the autophagy-related gene lgg-1 and atg-18, and nematodes carrying GFP reporter were induced to form autophagosomes (GFP::LGG-1) after T. marneffei infection. Furthermore, the knockdown of lgg-1 significantly reduced the survival rate of T. marneffei-infected nematodes. Likewise, the autophagy activator rapamycin reduced the fungal burden and suppressed lung inflammation in a mouse model of infection. In conclusion, autophagy is essential for host defense against T. marneffei in vitro and in vivo. Therefore, autophagy may be an attractive target for developing new therapeutics to treat talaromycosis.

The Autophagy Marker LC3 Is Processed during the Sperm Capacitation and the Acrosome Reaction and Translocates to the Acrosome Where It Colocalizes with the Acrosomal Membranes in Horse Spermatozoa

Despite its importance in somatic cells and during spermatogenesis, little is known about the role that autophagy may play in ejaculated spermatozoa. Our aim was to investigate whether the molecular components of autophagy, such as microtubule-associated protein 1 light chain 3 (LC3), are activated in stallion spermatozoa during the capacitation and acrosome reaction and if this activation could modulate these biological processes. To analyze the autophagy turnover, LC3I and LC3II proteins were assessed by western blotting, and the ratio between both proteins (LC3II/LC3I) was calculated. In somatic cells, this ratio indicates that autophagy has been activated and similar LC3 processing has been described in mammalian spermatozoa. The subcellular localization of autophagy-related proteins was assessed by immunofluorescence with specific antibodies that recognized Atg16, Beclin-1, and LC3. The colocalization of acrosomal membranes (PNA) and LC3 was studied by confocal microcopy, and the acrosome reacted cells were quantified by flow cytometry. The incubation of stallion sperm in capacitating conditions (BWW; 3 h) significantly increased LC3 processing. This increment was three to four times higher after the induction of the acrosome reaction in these cells. LC3 was mainly expressed in the head in mature ejaculated sperm showing a clear redistribution from the post-acrosomal region to the acrosome upon the incubation of sperm in capacitating conditions (BWW, 3 h). After the induction of the acrosome reaction, LC3 colocalized with the acrosome or the apical plasmalemma membranes in the head of the stallion spermatozoa. The inhibition or activation of autophagy-related pathways in the presence of autophagy activators (STF-62247) or inhibitors (E-64d, chloroquine) significantly increased LC3 processing and increased the percent of acrosome reacted cells, whereas 3-methyladenine almost completely inhibited LC3 processing and the acrosome reaction. In conclusion, we found that sperm capacitation and acrosome reaction could be regulated by autophagy components in sperm cells ex vivo by processes that might be independent of the intraluminal pH of the acrosome and dependent of LC3 lipidation. It can be speculated that, in stallion sperm, a form of noncanonical autophagy utilizes some components of autophagy machinery to facilitate the acrosome reaction.

Bioimaging of Lysosomes with a BODIPY pH-Dependent Fluorescent Probe

Fluorescence-based probes represent a powerful tool for noninvasive imaging of living systems in real time and with a high temporal and spatial resolution. Amongst several known fluorophores, 3-difluoroborodipyrromethene (BODIPY) derivatives have become a cornerstone for innovative fluorescent labelling applications, mainly due to their advantageous features including their facile synthesis, structural versatility and exceptional photophysical properties. In this context, we report a BODIPY-based fluorescent probe for imaging of lysosomes in living cells. The BODIPY derivative displayed a remarkable fluorescence enhancement at low pH values with a pK_a* of 3.1. In vitro studies by confocal microscopy in HeLa cells demonstrated that the compound was able to permeate cell membrane and selectively label lysosome whilst remaining innocuous to the cell culture at the maximum concentration tested. Herein, the BODIPY derivative holds the promise of investigating lysosomal dynamics and function in living cells through fluorescence imaging.

Bartonella taylorii: A Model Organism for Studying Bartonella Infection in vitro and in vivo

Bartonella spp. are Gram-negative facultative intracellular pathogens that infect diverse mammals and cause a long-lasting intra-erythrocytic bacteremia in their natural host. These bacteria translocate Bartonella effector proteins (Beps) into host cells via their VirB/VirD4 type 4 secretion system (T4SS) in order to subvert host cellular functions, thereby leading to the downregulation of innate immune responses. Most studies on the functional analysis of the VirB/VirD4 T4SS and the Beps were performed with the major zoonotic pathogen Bartonella henselae for which efficient in vitro infection protocols have been established. However, its natural host, the cat, is unsuitable as an experimental infection model. In vivo studies were mostly confined to rodent models using rodent-specific Bartonella species, while the in vitro infection protocols devised for B. henselae are not transferable for those pathogens. The disparities of in vitro and in vivo studies in different species have hampered progress in our understanding of Bartonella pathogenesis. Here we describe the murine-specific strain Bartonella taylorii IBS296 as a new model organism facilitating the study of bacterial pathogenesis both in vitro in cell cultures and in vivo in laboratory mice. We implemented the split NanoLuc luciferase-based translocation assay to study BepD translocation through the VirB/VirD4 T4SS. We found increased effector-translocation into host cells if the bacteria were grown on tryptic soy agar (TSA) plates and experienced a temperature shift immediately before infection. The improved infectivity in vitro was correlating to an upregulation of the VirB/VirD4 T4SS. Using our adapted infection protocols, we showed BepD-dependent immunomodulatory phenotypes in vitro. In mice, the implemented growth conditions enabled infection by a massively reduced inoculum without having an impact on the course of the intra-erythrocytic bacteremia. The established model opens new avenues to study the role of the VirB/VirD4 T4SS and the translocated Bep effectors in vitro and in vivo.

The Impact of Bartonella VirB/VirD4 Type IV Secretion System Effectors on Eukaryotic Host Cells

Bartonella spp. are facultative intracellular pathogens that infect a wide range of mammalian hosts including humans. The VirB/VirD4 type IV secretion system (T4SS) is a key virulence factor utilized to translocate Bartonella effector proteins (Beps) into host cells in order to subvert their functions. Crucial for effector translocation is the C-terminal Bep intracellular delivery (BID) domain that together with a positively charged tail sequence forms a bipartite translocation signal. Multiple BID domains also evolved secondary effector functions within host cells. The majority of Beps possess an N-terminal filamentation induced by cAMP (FIC) domain and a central connecting oligonucleotide binding (OB) fold. FIC domains typically mediate AMPylation or related post-translational modifications of target proteins. Some Beps harbor other functional modules, such as tandem-repeated tyrosine-phosphorylation (EPIYA-related) motifs. Within host cells the EPIYA-related motifs are phosphorylated, which facilitates the interaction with host signaling proteins. In this review, we will summarize our current knowledge on the molecular functions of the different domains present in Beps and highlight examples of Bep-dependent host cell modulation.

Identification of an Autophagy-Related lncRNA Prognostic Signature and Related Tumor Immunity Research in Lung Adenocarcinoma

Autophagy is closely associated with the tumor immune microenvironment (TIME) and prognosis of patients with lung adenocarcinoma (LUAD). In the present study, we established a signature on the basis of long noncoding RNAs (lncRNAs) related to autophagy (ARlncRNAs) to investigate the TIME and survival of patients with LUAD. We selected ARlncRNAs associated with prognosis to construct a model and divided each sample into different groups on the basis of risk score. The ARlncRNA signature could be recognized as an independent prognostic factor for patients with LUAD, and patients in the low-risk group had a greater survival advantage. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analysis suggested that several immune functions and pathways were enriched in different groups. A high-risk score correlated significantly negatively with high abundance of immune cells and stromal cells around the tumor and high tumor mutational burden. Low-risk patients had a higher PD-1, CTLA-4, and HAVCR2 expression and had a better efficacy of immune checkpoint inhibitors, including PD-1/CTLA-4 inhibitor. A reliable signature on the basis of ARlncRNAs was constructed to explore the TIME and prognosis of patients with LUAD, which could provide valuable information for individualized LUAD treatment.

Potential aquatic environmental risks of trifloxystrobin: Enhancement of virus susceptibility in zebrafish through initiation of autophagy

Chronic pollution in aquatic ecosystems can lead to many adverse effects, including a greater susceptibility to pathogens among resident biota. Trifloxystrobin (TFS) is a strobilurin fungicide widely used in Asia to control soybean rust. However, it has the potential to enter aquatic ecosystems, where it may impair fish resistance to viral infections. To explore the potential environmental risks of TFS, we characterized the antiviral capacities of fish chronically exposed to TFS and subsequently infected with spring viraemia of carp virus (SVCV). Although TFS exhibited no significant cytotoxicity at the tested environmental concentrations during viral challenge, SVCV replication increased significantly in a time-dependent manner within epithelioma papulosum cyprini (EPC) cells and zebrafish exposed to 25 μg/L TFS. Results showed that the highest viral load was more than 100-fold that of the controls. Intracellular biochemical assays indicated that autophagy was induced by TFS, and associated changes included an increase in autophagosomes, conversion of LC3-II, accumulation of Beclin-1, and degradation of P62 in EPC cells and zebrafish. In addition, TFS markedly decreased the expression and phosphorylation of mTOR, indicating that activation of TFS may be associated with the mTOR-mediated autophagy pathway. This study provides new insights into the mechanism of the immunosuppressive effects of TFS on non-target aquatic hosts and suggests that the existence of TFS in aquatic environments may contribute to outbreaks of viral diseases.

A preliminary investigation on the mechanism of action of 4-(8-(2-ethylimidazole)octyloxy)-arctigenin against IHNV

Arctigenin derivatives form an elite class of naturally occurring compounds that possess promising antiviral therapeutic perspectives. In a previous study, we design and synthesize a arctigenin derivative, 4-(8-(2-ethylimidazole)octyloxy)-arctigenin (EOA), to evaluate its antiviral activity on infectious hematopoietic necrosis virus (IHNV). In this study, we find that the half maximal inhibitory concentrations (IC₅₀) of EOA on IHNV nucleoprotein (N), phosphoprotein (P), matrix protein (M), nonvirion protein (NV) and polymerase (L) mRNA expression is 0.92, 0.80, 0.98, 0.89 and 0.87 μM, respectively. Mechanistically, our results show that EOA do not damage the viral particles directly, indicating EOA does not possess antiviral activity by destroying virions. Viral binding assays reveal that EOA do not interfere with IHNV adsorption. Because rapamycin has been shown to exhibit anti-IHNV activity by inducing autophagy of epithelioma papulosum cyprini (EPC) cells, we further investigate the relationship between EOA and autophagy in EPC cells. Autophagy fluorescence detection shows that EPC cells have a strong autophagy body after being treated with derivative EOA. The electron microscopy results show that EOA could induce typical autophagosomes which are representative structures of autophagy activation. Moreover, the punctate accumulation of green fluorescence-tagged microtubule-associate protein 1 light chain 3 (LC3) and the protein conversion from LC3-I to LC3-II are respectively confirmed by confocal fluorescence microscopy and western blotting. Overall, these findings demonstrate that EOA plays an anti-IHNV role via inducing autophagy in EPC cells.

Protein phosphatase 2A has an essential role in promoting thymocyte survival during selection

The development of thymocytes to mature T cells in the thymus is tightly controlled by cellular selection, in which only a small fraction of thymocytes equipped with proper quality of TCRs progress to maturation. It is pivotal to protect the survival of the few T cells, which pass the selection. However, the signaling events, which safeguard the cell survival in thymus, are not totally understood. In this study, protein Ser/Thr phosphorylation in thymocytes undergoing positive selection is profiled by mass spectrometry. The results revealed large numbers of dephosphorylation changes upon T cell receptor (TCR) activation during positive selection. Subsequent substrate analysis pinpointed protein phosphatase 2A (PP2A) as the enzyme responsible for the dephosphorylation changes in developing thymocytes. PP2A catalytic subunit α (Ppp2ca) deletion in the T cell lineage in Ppp2ca ^flox/flox-Lck-Cre mice (PP2A cKO) displayed dysregulated dephosphorylation of apoptosis-related proteins in double-positive (DP) cells and caused substantially decreased numbers of DP CD4⁺ CD8⁺ cells. Increased levels of apoptosis in PP2A cKO DP cells were found to underlie aberrant thymocyte development. Finally, the defective thymocyte development in PP2A cKO mice could be rescued by either Bcl2 transgene expression or by p53 knockout. In summary, our work reveals an essential role of PP2A in promoting thymocyte development through the regulation of cell survival.

Gemcitabine induces apoptosis and autophagy via the AMPK/mTOR signaling pathway in pancreatic cancer cells

Gemcitabine (GEM)-based chemotherapy is a commonly used treatment for pancreatic cancer. However, acquired drug resistance, a major problem in pancreatic cancer treatment, causes a reduction in the survival rate of patients with cancer. In this study, we attempted to reveal the molecular mechanism of GEM resistance. Our data showed that GEM treatment inhibits cell growth, induces apoptosis, and activates autophagy via the AMP-activated protein kinase (AMPK) pathway. The combination of GEM treatment and AMPK knockdown resulted in a dramatic increase of apoptosis and inhibition of autophagy. Additionally, inhibition of mammalian target of Rapamycin induced autophagy. Our findings show the potential therapeutic implications of the combined treatment with GEM and AMPK inhibitors for pancreatic cancer.

A new coumarin derivative plays a role in rhabdoviral clearance by interfering glycoprotein function during the early stage of viral infection

Coumarin forms an elite class of naturally occurring compounds that possess promising antiviral therapeutic perspectives. In this study, a coumarin derivative 7-[6-(2-methylimidazole) hexyloxy] coumarin (D5) was designed and synthesized to evaluate antiviral activity on a rhabdovirus, spring viraemia of carp virus (SVCV). Our results demonstrated that D5 had a robust antiviral activity with >90% inhibitory rate of SVCV expression in the host cells. And D5 significantly reduced viral-induced apoptosis and recovered virus-activated caspase-3/8/9 activities. Further data determined that SVCV could alter the cytoskeletal structure of EPC cells, characterized by a circumferential ring of microtubules and a disrupted microfilament organization, whereas cytoskeleton structure in D5-treated cells kept the normal morphology. Mechanistically speaking, D5 could interfere with SVCV replication inside or outside of cells through two different approaches. Before the process of virus entry into EPC cells, D5 had an impact on SVCV glycoprotein structure so as to disrupt viral binding to the cell surface or translocation to the cytosol. Another strategy for D5 to against SVCV was that D5 significantly suppressed SVCV-activated autophagy, which was beneficial for the host cells to restrict SVCV viral replication, accompanied by a higher phosphorylation of Akt-mTOR. In summary, our results revealed that D5 was effective in weakening SVCV infection and regulating SVCV-induced undesirable conditions, and this compound provided new therapeutic implications for the treatment of rhabdoviruses.

Persistent Intracellular Staphylococcus aureus in Keratinocytes Lead to Activation of the Complement System with Subsequent Reduction in the Intracellular Bacterial Load

The complement system is an ancient part of the innate immune system important for both tissue homeostasis and host defense. However, bacteria like Staphylococcus aureus (SA) possess elaborative mechanisms for evading both the complement system and other parts of the immune system. One of these evasive mechanisms—important in causing chronic and therapy resistant infections—is the intracellular persistence in non-immune cells. The objective of our study was to investigate whether persistent intracellular SA infection of epidermal keratinocytes resulted in complement activation. Using fluorescence microscopy, we found that persistent SA, surviving intracellularly in keratinocytes, caused activation of the complement system with formation of the terminal complement complex (TCC) at the cell surface. Skin samples from atopic dermatitis patients analyzed by bacterial culture and microscopy, demonstrated that SA colonization was associated with the presence of intracellular bacteria and deposition of the TCC in epidermis in vivo. Complement activation on keratinocytes with persistent intracellular bacteria was found with sera deficient/depleted of the complement components C1q, Mannan-binding lectin, or complement factor B, demonstrating involvement of more than one complement activation pathway. Viable bacterial counts showed that complement activation at the cell surface initiated cellular responses that significantly reduced the intracellular bacterial burden. The use of an inhibitor of the extracellular signal-regulated kinase (ERK) abrogated the complement-induced reduction in intracellular bacterial load. These data bridge the roles of the complement system in tissue homeostasis and innate immunity and illustrate a novel mechanism by which the complement system combats persistent intracellular bacteria in epithelial cells.

Pseudorabies virus induces autophagy to enhance viral replication in mouse neuro-2a cells in vitro

Autophagy of cytoplasmic components plays an essential role in the pathogenic infection process. Furthermore, research suggests that autophagy is an extremely important component of the innate immune response. Our study aimed to reveal the effect of virus-induced autophagy on pseudorabies virus (PRV) replication. Our results confirmed that light chain 3 (LC3)-I was converted into LC3-II after PRV infection; this transition is considered an important indicator of autophagy. Transmission electron microscopy (TEM) revealed that PRV infection could notably increase the number of autophagosomes in mouse neuro-2a (N2a) cells. In addition, LC3-II accumulated in response to chloroquine (CQ) treatment, indicating that PRV infection induced a complete autophagic flux response. Furthermore, our analyses verified differences in the magnitude of autophagy induction by two different PRV isolates, LA and ZJ01. Subsequent analysis showed that the induction of autophagy by rapamycin facilitated PRV replication, while inhibition of autophagy by 3-methyladenine (3-MA) reduced PRV replication. These results indicated that PRV induced autophagy via the classical Beclin-1-Atg7-Atg5 pathway to enhance viral replication in N2a cells in vitro.

Differential immune response of influenza A virus-infected dendritic cells and association with autophagy

Aim: We sought to study the responses of dendritic cells (DCs) after direct stimulation by different influenza A viruses. Materials & methods: Using bone marrow-derived DCs (BMDCs) as a model, we measured the expression of surface markers, cytokine production and the priming effect on CD4+ naive T cells. Results & conclusion: We found that all of the tested viruses induced BMDC maturation. Cytokine expression assays also demonstrated that activated BMDCs secrete higher levels of cytokines. Similar to the maturation degree, well-stimulated BMDCs induced higher levels of naive CD4+ T-cell activation. Furthermore, we found that the PR8 and WSN influenza A viruse-induced BMDC functional activation was at least partially influenced by autophagy.

Contribution of inflammatory pathways to Fabry disease pathogenesis

Lysosomal storage diseases are usually considered to be pathologies in which the passive deposition of unwanted materials leads to functional changes in lysosomes. Lysosomal deposition of unmetabolized glycolipid substrates stimulates the activation of pathogenic cascades, including immunological processes, and particularly the activation of inflammation. In lysosomal storage diseases, the inflammatory response is continuously being activated because the stimulus cannot be eliminated. Consequently, inflammation becomes a chronic process. Lysosomes play a role in many steps of the immune response. Leukocyte perturbation and over-expression of immune molecules have been reported in Fabry disease. Innate immunity is activated by signals originating from dendritic cells via interactions between toll-like receptors and globotriaosylceramide (Gb3) and/or globotriaosylsphingosine (lyso-Gb3). Evidence indicates that these glycolipids can activate toll-like receptors, thus triggering inflammation and fibrosis cascades. In the kidney, Gb3 deposition is associated with the increased release of transforming growth factor beta and with epithelial-to-mesenchymal cell transition, leading to the over-expression of pro-fibrotic molecules and to renal fibrosis. Interstitial fibrosis is also a typical feature of heart involvement in Fabry disease. Endomyocardial biopsies show infiltration of lymphocytes and macrophages, suggesting a role for inflammation in causing tissue damage. Inflammation is present in all tissues and may be associated with other potentially pathologic processes such as apoptosis, impaired autophagy, and increases in pro-oxidative molecules, which could all contribute synergistically to tissue damage. In Fabry disease, the activation of chronic inflammation over time leads to organ damage. Therefore, enzyme replacement therapy must be started early, before this process becomes irreversible.

Association of ATG16L1 gene haplotype with inflammatory bowel disease in Indians

Inflammatory bowel disease (IBD) is characterized by multigenic inheritance. Defects in autophagy related genes are considered to show genetic heterogeneity between populations. We evaluated the association of several single nucleotide polymorphisms (SNPs) in the autophagy related 16 like 1 (ATG16L1) gene with IBD in Indians. The ATG16L1 gene was genotyped for ten different SNPs using DNA extracted from peripheral blood of 234 patients with Crohn's disease (CD), 249 patients with ulcerative colitis (UC) and 393 healthy controls The SNPs rs2241880, rs4663396, rs3792106, rs10210302, rs3792109, rs2241877, rs6737398, rs11682898, rs4663402 and rs4663421 were genotyped using the Sequenom MassArray platform. PLINK was used for the association analysis and pairwise linkage disequilibrium (LD) values. Haplotype analysis was done using Haploview. All SNPs were in Hardy Weinberg equilibrium in cases and controls. The G allele at rs6737398 exhibited a protective association with both CD and UC. The T allele at rs4663402 and C allele at rs4663421 were positively associated with CD and UC. The T allele at rs2241877 exhibited protective association with UC only. The AA genotype at rs4663402 and the GG genotype at rs4663421 were protectively associated with both CD and UC. Haplotype analysis revealed that all the SNPs in tight LD (D' = 0.76-1.0) and organized in a single haplotype block. Haplotype D was positively associated with IBD (P = 5.8 x 10-6 for CD and 0.002 for UC). SNPs in ATG16L1 were associated with IBD in Indian patients. The relevance to management of individual patients requires further study.

Targeting Autophagy for Oncolytic Immunotherapy

Oncolytic viruses (OVs) are capable of exerting anti-cancer effects by a variety of mechanisms, including immune-mediated tumor cell death, highlighting their potential use in immunotherapy. Several adaptation mechanisms such as autophagy contribute to OV-mediated anti-tumor properties. Autophagy regulates immunogenic signaling during cancer therapy which can be utilized to design therapeutic combinations using approaches that either induce or block autophagy to potentiate the therapeutic efficacy of OVs. In this article, we review the complicated interplay between autophagy, cancer, immunity, and OV, summarize recent progress in the contribution of OV-perturbed autophagy to oncolytic immunity, and discuss the challenges in targeting autophagy to enhance oncolytic immunotherapy.

Role of MicroRNA in the Lung's Innate Immune Response

The immune response to respiratory pathogens must be robust enough to defend the host yet properly constrained such that inflammation-induced tissue damage is avoided. MicroRNA (miRNA) are small noncoding RNA which posttranscriptionally influence gene expression. In this review, we discuss recent experimental evidence of the contribution of miRNA to the lung's response to bacterial and viral pathogens.

Autophagy and apoptosis induced by Chinese giant salamander (Andrias davidianus) iridovirus (CGSIV)

The outbreak of Chinese Giant Salamander (Andrias davidianus, CGS) Iridovirus (CGSIV) caused massive death of CGSs. However, some CGSs with low level of CGSIV usually could survive. In our study, major capsid protein (MCP) DNA replicates of CGSIV in shedding skin were employed to assess the relative content of CGSIV in the living CGSs by qPCR. Furthermore, the examinations of autophagy and apoptosis in CGSs in vivo and in the primary renal cells in vitro were performed, respectively. The results showed that the relative contents of CGSIV in the shedding skin could reflect those in liver, spleen, and kidney of the CGSs. In these tissues of the CGSs with low-level replicates of CGSIV, there were not obviously macroscopic lesions. But the irregularly-shaped vesicles perhaps involving in autophagosome were observed by transmission electron microscopy (TEM). The LC3B protein displayed uneven distribution by Immunohistochemistry and the level mRNA of Atg5 was higher in these tissues than that in the tissues of healthy CGSs using qRT-PCR. Meanwhile, the apoptosis also appeared in these tissues by TUNEL staining and higher level mRNA of type I IFN were detected in these tissues using qRT-PCR. Further, both the expression level of LC3B II protein and Atg5 mRNA increased significantly at 2h after the virus infected the primary renal cells from the health CGSs in vitro. In addition, apoptosis and type I IFN mRNA began to increase significantly at 4h after the virus infected the renal cells. It was suggested that autophagy may be a pivotal role for survival of CGSIV in the CGSs during early infection and the rapid proliferation of CGSIV could be inhibited by innate immune response and apoptosis.

Autophagy induced by snakehead fish vesiculovirus inhibited its replication in SSN-1 cell line

Autophagy plays an important role in host protection against pathogen infection through activating innate and adaptive immunity. In the present study, we observed that the infection of snakehead fish vesiculovirus (SHVV) could induce apparent autophagy in striped snakehead fish cell line (SSN-1), including clear double-membrane vesicles, fluorescent punctate pattern of microtubule-associated protein 1 light chain 3B (SSN-LC3B) and the conversion of SSN-LC3B-Ⅰ to SSN-LC3B-Ⅱ. Furthermore, we verified that autophagy inhibited the replication of SHVV by assessing mRNA and protein level of nucleoprotein as well as virus titer in the supernatant. These results will shed a new light on the prevention of the infection of SHVV.

The Role of Gammaherpesviruses in Cancer Pathogenesis

Worldwide, one fifth of cancers in the population are associated with viral infections. Among them, gammaherpesvirus, specifically HHV4 (EBV) and HHV8 (KSHV), are two oncogenic viral agents associated with a large number of human malignancies. In this review, we summarize the current understanding of the molecular mechanisms related to EBV and KSHV infection and their ability to induce cellular transformation. We describe their strategies for manipulating major cellular systems through the utilization of cell cycle, apoptosis, immune modulation, epigenetic modification, and altered signal transduction pathways, including NF-kB, Notch, Wnt, MAPK, TLR, etc. We also discuss the important EBV latent antigens, namely EBNA1, EBNA2, EBNA3’s and LMP’s, which are important for targeting these major cellular pathways. KSHV infection progresses through the engagement of the activities of the major latent proteins LANA, v-FLIP and v-Cyclin, and the lytic replication and transcription activator (RTA). This review is a current, comprehensive approach that describes an in-depth understanding of gammaherpes viral encoded gene manipulation of the host system through targeting important biological processes in viral-associated cancers.

Sampling From the Proteome to the Human Leukocyte Antigen-DR (HLA-DR) Ligandome Proceeds Via High Specificity

Comprehensive analysis of the complex nature of the Human Leukocyte Antigen (HLA) class II ligandome is of utmost importance to understand the basis for CD4⁺ T cell mediated immunity and tolerance. Here, we implemented important improvements in the analysis of the repertoire of HLA-DR-presented peptides, using hybrid mass spectrometry-based peptide fragmentation techniques on a ligandome sample isolated from matured human monocyte-derived dendritic cells (DC). The reported data set constitutes nearly 14 thousand unique high-confident peptides, i.e. the largest single inventory of human DC derived HLA-DR ligands to date. From a technical viewpoint the most prominent finding is that no single peptide fragmentation technique could elucidate the majority of HLA-DR ligands, because of the wide range of physical chemical properties displayed by the HLA-DR ligandome. Our in-depth profiling allowed us to reveal a strikingly poor correlation between the source proteins identified in the HLA class II ligandome and the DC cellular proteome. Important selective sieving from the sampled proteome to the ligandome was evidenced by specificity in the sequences of the core regions both at their N- and C- termini, hence not only reflecting binding motifs but also dominant protease activity associated to the endolysosomal compartments. Moreover, we demonstrate that the HLA-DR ligandome reflects a surface representation of cell-compartments specific for biological events linked to the maturation of monocytes into antigen presenting cells. Our results present new perspectives into the complex nature of the HLA class II system and will aid future immunological studies in characterizing the full breadth of potential CD4⁺ T cell epitopes relevant in health and disease.

NK and B cell deficiency in a MPS type II family with novel mutation in the IDS gene

The mucopolysaccharidoses (MPSs) are a group of rare, inherited lysosomal storage disorders that are clinically characterized by abnormalities in multiple organ systems and reduced life expectancy. Whereas the lysosome is essential to the functioning of the immune system, some authors suggest that the MPS patients have abnormalities in the immune system similar to the patients with primary immunodeficiency. In this study, we evaluated 8 male MPS type II patients of the same family with novel mutation in the IDS gene. We found in this MPS family a quantitative deficiency of NK and B cells with normal values of IgG, IgM and IgA serum antibodies and normal response to polysaccharide antigens. Interestingly, abnormalities found in these patients were not observed in other MPS patients, suggesting that the type of mutation found in the IDS gene can be implicated in the immunodeficiency.

Japanese encephalitis virus replication is negatively regulated by autophagy and occurs on LC3-I- and EDEM1-containing membranes

Autophagy is a lysosomal degradative pathway that has diverse physiological functions and plays crucial roles in several viral infections. Here we examine the role of autophagy in the life cycle of JEV, a neurotropic flavivirus. JEV infection leads to induction of autophagy in several cell types. JEV replication was significantly enhanced in neuronal cells where autophagy was rendered dysfunctional by ATG7 depletion, and in Atg5-deficient mouse embryonic fibroblasts (MEFs), resulting in higher viral titers. Autophagy was functional during early stages of infection however it becomes dysfunctional as infection progressed resulting in accumulation of misfolded proteins. Autophagy-deficient cells were highly susceptible to virus-induced cell death. We also observed JEV replication complexes that are marked by nonstructural protein 1 (NS1) and dsRNA colocalized with endogenous LC3 but not with GFP-LC3. Colocalization of NS1 and LC3 was also observed in Atg5 deficient MEFs, which contain only the nonlipidated form of LC3. Viral replication complexes furthermore show association with a marker of the ER-associated degradation (ERAD) pathway, EDEM1 (ER degradation enhancer, mannosidase α-like 1). Our data suggest that virus replication occurs on ERAD-derived EDEM1 and LC3-I-positive structures referred to as EDEMosomes. While silencing of ERAD regulators EDEM1 and SEL1L suppressed JEV replication, LC3 depletion exerted a profound inhibition with significantly reduced RNA levels and virus titers. Our study suggests that while autophagy is primarily antiviral for JEV and might have implications for disease progression and pathogenesis of JEV, nonlipidated LC3 plays an important autophagy independent function in the virus life cycle.

T300A GENETIC POLYMORPHISM: a susceptibility factor for Crohn’s disease?

ContextCrohn’s disease is characterized by a chronic and debilitating inflammatory disorder of the gastrointestinal tract. Several factors may contribute to its development. From extensive studies of the human genome, the polymorphism T300A of the gene ATG16L1 (autophagy-related 16-like 1) has been related to increased risk of developing this disease.ObjectivesAnalyze the role of polymorphism T300A (rs2241880) in patients with Crohn’s disease.Methods238 samples from (control group) and 106 samples from patients with Crohn’s disease recruited at five Southern Brazilian reference centers were evaluated. The genotyping consisted of the amplification via Polymerase Chain Reaction of the genomic segment encompassing T300A, followed by Restriction Fragment Length Polymorphism analysis. The amplicons and fragments were separated by agarose gel electrophoresis and confirmed under ultraviolet light.ResultsThe genotype AG was more prevalent among patients and controls (50% vs 44.8%), followed by genotypes AA (26.4% vs 35.1%) and GG (23.6% vs 20.1%). The frequency of the allele G of the polymorphism T300A was higher in the group of patients with Crohn’s disease (48.6%) than in controls (42.4%), although not reaching statistical significance.ConclusionsIt was not possible to confirm the increased susceptibility on development of Crohn’s disease conferred by polymorphism T300A.

The influence of probiotics on zebrafish Danio rerio innate immunity and hepatic stress

In this study, the effects of probiotic administration on zebrafish Danio rerio intestinal innate immunity and hepatic stress were evaluated. Zebrafish adults were treated for 10 days with the probiotic Lactobacillus rhamnosus IMC 501(®). To assess the effects at the molecular level, the mRNA levels of genes involved in the innate immune system, stress response, oxidative stress, and apoptosis were quantified by real-time polymerase chain reaction. An increase of biomarkers related to innate immune responses was observed in intestinal tissue from the probiotic-treated fish compared with the control fish. In addition, a decrease in the abundance of stress and apoptotic-related genes was observed in the liver of the probiotic-fed fish. Finally, imaging Fourier transform infrared analysis was conducted on liver sections and the data obtained confirmed that probiotic administration decreased oxidative stress levels, decreased DNA damage, and increased lipid saturation levels. Overall, the results show that probiotic administration may enhance zebrafish welfare by modulating the innate immune response and improving hepatic stress tolerance.

Suppression of autophagic genes sensitizes CUG2-overexpressing A549 human lung cancer cells to oncolytic vesicular stomatitis virus-induced apoptosis

We showed in our previous study that cancer upregulated gene (CUG) 2, a novel oncogene, confers resistance to infection of oncolytic vesicular stomatitis virus (VSV) by activating Stat1-mediated signal transduction. Since many studies have reported that autophagy is involved in virus replication, we investigated whether autophagy also plays a role in the antiviral activity in A549 cells overexpressing CUG2 (A549-CUG2). We suppressed Atg5 or Beclin 1 expression using siRNA and examined its effect on the susceptibility of cells to infection by oncolytic VSV. We found that A549-CUG2 cells treated with Atg5 or Beclin 1 siRNA became susceptible to VSV infection, whereas A549-CUG2 cells treated with control siRNA were resistant. This result suggests that autophagy is involved in the antiviral response of A549-CUG2 cells. Further investigation revealed that autophagy impairment enhanced the generation of reactive oxygen species (ROS), which resulted in inactivation of S6 kinase. Under these conditions, the levels of ISG15 transcript and protein decreased, which conferred on A549-CUG2 cell susceptibility to VSV infection. Finally, we found that overloading of H₂O₂ sensitized control A549-CUG2 cells to VSV-induced apoptosis. Taken together, these results indicate that autophagy impairment induces excessive ROS formation, which decreases S6 kinase activity and ISG15 expression, ultimately rendering the A549-CUG2 cells susceptible to VSV infection. We propose that autophagy impairment is a potential strategy for successful VSV virotherapy of CUG2-overexpressing tumors.

Immunodominance in CD4 T-cell responses: implications for immune responses to influenza virus and for vaccine design

CD4 T cells play a primary role in regulating immune responses to pathogenic organisms and to vaccines. Antigen-specific CD4 T cells provide cognate help to B cells, a requisite event for immunoglobulin switch and affinity maturation of B cells that produce neutralizing antibodies and also provide help to cytotoxic CD8 T cells, critical for their expansion and persistence as memory cells. Finally, CD4 T cells may participate directly in pathogen clearance via cell-mediated cytotoxicity or through production of cytokines. Understanding the role of CD4 T-cell immunity to viruses and other pathogens, as well as evaluation of the efficacy of vaccines, requires insight into the specificity of CD4 T cells. This review focuses on the events within antigen-presenting cells that focus CD4 T cells toward a limited number of peptide antigens within the pathogen or vaccine. The molecular events are discussed in light of the special challenges that the influenza virus poses, owing to the high degree of genetic variability, unpredictable pathogenicity and the repeated encounters that human populations face with this highly infectious pathogenic organism.

Neutrophil cell death in response to infection and its relation to coagulation

Neutrophil is a major player in the pathophysiology of severe sepsis. Recent studies have revealed that the cell death mechanism of neutrophils directly relates to the development of organ dysfunction during sepsis. Here we discuss about the different types of neutrophil cell death such as necrosis, apoptosis, autophagy, and the unique cell death style dubbed NETosis. NETosis cells release neutrophil extracellular traps (NETs), which are composed of chromatin bound to granular and nucleic proteins. The primary purpose of NET release is thought to be the control of microbial infections; however, it acts as a danger signal for the host as well. The harmful substances such as DNA, histones, and high-mobility group box 1 (HMGB1) and many other danger-associated molecular patterns (DAMPs) released along with NETosis or from necrotic neutrophils also contribute to the pathogenesis of sepsis. At the same time, the coagulation system, which is closely tied to these neutrophil cell death mechanisms, is often over-activated. It is well known that individual bacterial pathogens express virulence factors that modulate cell death pathways and influence the coagulation disorder during sepsis. Moreover, extensive cross talk exists between these two phenomena, whereby inflammation leads to activation of coagulation and coagulation considerably affects inflammatory activity. A greater knowledge of cell death pathways in sepsis informs the potential for future therapies designed to ameliorate excessive immune responses during sepsis.

Autophagy, a novel pathway to regulate calcium mobilization in T lymphocytes

The T lymphocyte response initiates with the recognition of MHC/peptides on antigen presenting cells by the T cell receptor (TCR). After the TCR engagement, the proximal signaling pathways are activated for downstream cellular events. Among these pathways, the calcium-signaling flux is activated through the depletion of endoplasmic reticulum (ER) calcium stores and plays pivotal roles in T cell proliferation, cell survival, and apoptosis. In studying the roles of macroautophagy (hereafter referred to as autophagy) in T cell function, we found that a pathway for intracellular degradation, autophagy, regulates calcium signaling by developmentally maintaining the homeostasis of the ER. Using mouse genetic models with specific deletion of autophagy-related genes in T lymphocytes, we found that the calcium influx is defective and the calcium efflux is increased in autophagy-deficient T cells. The abnormal calcium flux is related to the expansion of the ER and higher calcium stores in the ER. Because of this, treatment with the ER sarco/ER Ca²⁺-ATPase pump inhibitor, thapsigargin, rescues the calcium influx defect in autophagy-deficient T cells. Therefore, autophagy regulates calcium mobilization in T lymphocytes through ER homeostasis.

Dual role of chloroquine in liver ischemia reperfusion injury: reduction of liver damage in early phase, but aggravation in late phase

The anti-malaria drug chloroquine is well known as autophagy inhibitor. Chloroquine has also been used as anti-inflammatory drugs to treat inflammatory diseases. We hypothesized that chloroquine could have a dual effect in liver ischemia/reperfusion (I/R) injury: chloroquine on the one hand could protect the liver against I/R injury via inhibition of inflammatory response, but on the other hand could aggravate liver I/R injury through inhibition of autophagy. Rats (n=6 per group) were pre-treated with chloroquine (60 mg/kg, i.p.) 1 h before warm ischemia, and they were continuously subjected to a daily chloroquine injection for up to 2 days. Rats were killed 0.5, 6, 24 and 48 h after reperfusion. At the early phase (i.e., 0–6 h after reperfusion), chloroquine treatment ameliorated liver I/R injury, as indicated by lower serum aminotransferase levels, lower hepatic inflammatory cytokines and fewer histopathologic changes. In contrast, chloroquine worsened liver injury at the late phase of reperfusion (i.e., 24–48 h after reperfusion). The mechanism of protective action of chloroquine appeared to involve its ability to modulate mitogen-activated protein kinase activation, reduce high-mobility group box 1 release and inflammatory cytokines production, whereas chloroquine worsened liver injury via inhibition of autophagy and induction of hepatic apoptosis at the late phase. In conclusion, chloroquine prevents ischemic liver damage at the early phase, but aggravates liver damage at the late phase in liver I/R injury. This dual role of chloroquine should be considered when using chloroquine as an inhibitor of inflammation or autophagy in I/R injury.

Autophagy protects type II alveolar epithelial cells from Mycobacterium tuberculosis infection

This study was designed to investigate the protective effect of the autophagy signaling pathway against Mycobacterium tuberculosis infection in type II alveolar epithelial cells. An in vitro M. tuberculosis system was established using human A549 cells. Infection-induced changes in the expression of the autophagic marker LC3 were assessed by reverse transcription-PCR and Western blotting. Morphological changes in autophagosomes were detected by transmission electron microscopy (TEM). The function of the autophagy signaling pathway during infection was assessed by measuring the level of cell death and the amount of lactate dehydrogenase (LDH) released in the presence or absence of the inhibitor 3-methyladenine (3-MA). In addition, effects on LDH release were assessed after the siRNA-mediated knockdown of the essential autophagosomal structural membrane protein Atg5. LC3 mRNA expression was significantly reduced in M.tuberculosis-infected A549 cells (16888.76 ± 1576.34 vs. uninfected: 12744.29 ± 1089.37; P < 0.05). TEM revealed M.tuberculosis bacilli-containing compartments that were surrounded by double membranes characteristic of the autophagic process. M.tuberculosis-infected A549 cells released more LDH (1.45 ± 0.12 vs. uninfected: 0.45 ± 0.04; P < 0.05). The inhibition of autophagy signaling significantly enhanced M.tuberculosis-induced necrosis (3-MA: 75 ± 5% vs. untreated: 15 ± 1%; P < 0.05) and LDH release (3-MA: 2.50 ± 0.24 vs. untreated: 0.45 ± 0.04; Atg5 knockdown: 3.19 ± 0.29 vs. untreated: 1.28 ± 0.11; P < 0.05). Our results indicate that autophagy signaling pathway prevents apoptosis in type II alveolar epithelial cells infected with M.tuberculosis and may represent a molecular target for promoting cell survival during infection by respiratory pathogens.

Self-eating and self-defense: autophagy controls innate immunity and adaptive immunity

Autophagy (macroautophagy; "self-eating") is a degradation process, in which cytoplasmic content is engulfed and degraded by the lysosome. And, immunity is an important mechanism of the "self-defense" system. Autophagy has long been recognized as a stress response to nutrient deprivation. This will provide energy and anabolic building blocks to maintain cellular bioenergetic homeostasis. Thus, autophagy plays critical roles in regulating a wide variety of pathophysiological processes, including tumorigenesis, embryo development, tissue remodeling, and most recently, immunity. The latter shows that a self-eating (autophagy) process could regulate a self-defense (immune) system. In this review, we summarize the recent findings regarding the regulatory and mechanistic insights of the autophagy pathway in immunity.

Porcine reproductive and respiratory syndrome virus induces autophagy to promote virus replication

An increasing number of studies demonstrate that autophagy, an intrinsic mechanism that can degrade cytoplasmic components, is involved in the infection processes of a variety of pathogens. It can be hijacked by various viruses to facilitate their replication. In this study, we found that PRRSV infection significantly increases the number of double- or single-membrane vesicles in the cytoplasm of host cells in ultrastructural analysis. Our results showed the LC3-I was converted into LC3-II after virus infection, suggesting the autophagy machinery was activated. We further used pharmacological agents and shRNAs to confirm that autophagy promoted the replication of PRRSV in host cells. Confocal microscopy analysis showed that PRRSV inhibited the fusion between autophagosomes and lysosomes, suggesting that PRRSV induced incomplete autophagy. This suppression caused the accumulation of autophagosomes which may serve as replication site to enhance PRRSV replication. It has been shown that NSP2 and NSP3 of arterivirus are two components of virus replication complex. We also found in our studies that NSP2 colocalized with LC3 in MARC-145 cells by performing confocal microscopy analysis and continuous density gradient centrifugation. Our studies presented here indicated that autophagy was activated during PRRSV infection and enhanced PRRSV replication in host cells by preventing autophagosome and lysosome fusion.

Involvement of the autophagy pathway in trafficking of Mycobacterium tuberculosis bacilli through cultured human type II epithelial cells

Interactions between Mycobacterium tuberculosis bacilli and alveolar macrophages have been extensively characterized, while similar analyses in epithelial cells have not been performed. In this study, we microscopically examined endosomal trafficking of M. tuberculosis strain Erdman in A549 cells, a human type II pneumocyte cell line. Immuno-electron microscopic (IEM) analyses indicate that M. tuberculosis bacilli are internalized to a compartment labelled first with Rab5 and then with Rab7 small GTPase proteins. This suggests that, unlike macrophages, M. tuberculosis bacilli traffic to late endosomes in epithelial cells. However, fusion of lysosomes with the bacteria-containing compartment appears to be inhibited, as illustrated by IEM studies employing LAMP-2 and cathepsin-L antibodies. Examination by transmission electron microscopy and IEM revealed M. tuberculosis-containing compartments surrounded by double membranes and labelled with antibodies against the autophagy marker Lc3, providing evidence for involvement and intersection of the autophagy and endosomal pathways. Interestingly, inhibition of the autophagy pathway using 3-methyladenine improved host cell viability and decreased numbers of viable intracellular bacteria recovered after 72 h post infection. Collectively, these data suggest that trafficking patterns for M. tuberculosis bacilli in alveolar epithelial cells differ from macrophages, and that autophagy is involved this process.

Macroautophagy Regulation during HIV-1 Infection of CD4+ T Cells and Macrophages

Autophagy is an intracellular mechanism whereby pathogens, particularly viruses, are destroyed in autolysosomes after their entry into targets cells. Therefore, to survive and replicate in host cells, viruses have developed multiple strategies to either counteract or exploit this process. The aim of this review is to outline the known relationships between HIV-1 and autophagy in CD4+ T lymphocytes and macrophages, two main HIV-1 cell targets. The differential regulation of autophagy in these two cell-types is highlighted and its potential consequences in terms of viral replication and physiopathology discussed.

Interaction between innate immunity and porcine reproductive and respiratory syndrome virus

Innate immunity provides frontline antiviral protection and bridges adaptive immunity against virus infections. However, viruses can evade innate immune surveillance potentially causing chronic infections that may lead to pandemic diseases. Porcine reproductive and respiratory syndrome virus (PRRSV) is an example of an animal virus that has developed diverse mechanisms to evade porcine antiviral immune responses. Two decades after its discovery, PRRSV is still one of the most globally devastating viruses threatening the swine industry. In this review, we discuss the molecular and cellular composition of the mammalian innate antiviral immune system with emphasis on the porcine system. In particular, we focus on the interaction between PRRSV and porcine innate immunity at cellular and molecular levels. Strategies for targeting innate immune components and other host metabolic factors to induce ideal anti-PRRSV protection are also discussed.

Host-microbe relationships in inflammatory bowel disease detected by bacterial and metaproteomic analysis of the mucosal-luminal interface

BACKGROUND

Host-microbe interactions at the intestinal mucosal-luminal interface (MLI) are critical factors in the biology of inflammatory bowel disease (IBD).

METHODS

To address this issue, we performed a series of investigations integrating analysis of the bacteria and metaproteome at the MLI of Crohn's disease, ulcerative colitis, and healthy human subjects. After quantifying these variables in mucosal specimens from a first sample set, we searched for bacteria exhibiting strong correlations with host proteins. This assessment identified a small subset of bacterial phylotypes possessing this host interaction property. Using a second and independent sample set, we tested the association of disease state with levels of these 14 "host interaction" bacterial phylotypes.

RESULTS

A high frequency of these bacteria (35%) significantly differentiated human subjects by disease type. Analysis of the MLI metaproteomes also yielded disease classification with exceptional confidence levels. Examination of the relationships between the bacteria and proteins, using regularized canonical correlation analysis (RCCA), sorted most subjects by disease type, supporting the concept that host-microbe interactions are involved in the biology underlying IBD. Moreover, this correlation analysis identified bacteria and proteins that were undetected by standard means-based methods such as analysis of variance, and identified associations of specific bacterial phylotypes with particular protein features of the innate immune response, some of which have been documented in model systems.

CONCLUSIONS

These findings suggest that computational mining of mucosa-associated bacteria for host interaction provides an unsupervised strategy to uncover networks of bacterial taxa and host processes relevant to normal and disease states. (Inflamm Bowel Dis 2012;).