Regulation of innate immune responses by autophagy-related proteins

Schisandra chinensis extract ameliorates age-related muscle wasting and bone loss in ovariectomized rats

Exercise and healthy diet consumption support healthy aging. Schisandra chinensis (Turcz.) also known as "Baill." has anti-inflammatory and antioxidant properties. However, the role of S. chinensis as an antiaging compound has yet to be demonstrated. This study elucidated the antiaging effect of S. chinensis ethanol-hexane extract (C1) and the effect of C1 treatment on muscle and bone following physical exercise in ovariectomized (OVX) rats. RAW 264.7, human diploid fibroblasts (HDFs), C2C12 myoblasts, bone marrow macrophages, and MC3T3-E1 cells were used for in vitro, and muscle and bone of OVX rats were used for in vivo study to demonstrate the effect of C1. The C1 significantly inhibited the expression of inflammatory molecules, β-galactosidase activity, and improved antioxidant activity via down-regulation of reactive oxygen species in RAW 264.7 and aged HDF cells. The C1 with exercise improved muscle regeneration in skeletal muscle of OVX rats by promoting mitochondrial biogenesis and autophagy. C1 induced osteoblast differentiation, and C1 + exercise modulated the bone formation and bone resorption in OVX rats. C1 exhibited anti-inflammatory, antioxidant, myogenic, and osteogenic effects. C1 with exercise improved age-related muscle wasting and bone loss. Therefore, S. chinensis may be a potential prevent agent for age-related diseases such as sarcopenia and osteoporosis.

A Young Blood Environment Decreases Aging of Senile Mice Kidneys

Whether changes in internal body environment affect kidney aging remains unclear. Specifically, it is unknown whether transplanted kidneys from older donors recover from tissue damage after placement in younger recipients. In this study, a parabiosis animal model was established to investigate the effects of a young internal body environment on aged kidneys. The animals were divided into six groups: young (Ycon) and old control (Ocon) groups, isochronic youth-youth group (Y-IP), elderly-elderly group (O-IP), and heterochronic youth (Y-HP) and elderly (O-HP) groups. After parabiosis, tubule and interstitial tissue scores in the O-HP group were significantly lower than in the Ocon and O-IP groups. The expression of aging-related protein p16 and SA-β-gal in the O-HP group was significantly reduced compared with the Ocon and O-IP groups. Autophagy factors Atg5 and LC3BII were significantly upregulated, whereas the expression of the autophagic degradation marker (P62) was significantly downregulated in the O-HP group compared with the Ocon and O-IP groups. With the same comparison, the positive cells of TUNEL staining and the expression of IL-6 and IL-1β were significantly reduced, whereas the total/cleaved caspase-3 and total/pNF-κB were significantly increased in the O-HP group. The results demonstrated that a young blood environment significantly reduces kidney aging. These findings provide new evidence supporting an increase in the upper age limit for human kidney transplantation donors.

Macrophage-Specific Hypoxia-Inducible Factor-1α Contributes to Impaired Autophagic Flux in Nonalcoholic Steatohepatitis

Inflammatory cell activation drives diverse cellular programming during hepatic diseases. Hypoxia-inducible factors (HIFs) have recently been identified as important regulators of immunity and inflammation. In nonalcoholic steatohepatitis (NASH), HIF-1α is upregulated in hepatocytes, where it induces steatosis; however, the role of HIF-1α in macrophages under metabolic stress has not been explored. In this study, we found increased HIF-1α levels in hepatic macrophages in methionine-choline-deficient (MCD) diet-fed mice and in macrophages of patients with NASH compared with controls. The HIF-1α increase was concomitant with elevated levels of autophagy markers BNIP3, Beclin-1, LC3-II, and p62 in both mouse and human macrophages. LysM^Cre HIF^dPA fl/fl mice, which have HIF-1α levels stabilized in macrophages, showed higher steatosis and liver inflammation compared with HIF^dPA fl/fl mice on MCD diet. In vitro and ex vivo experiments reveal that saturated fatty acid, palmitic acid (PA), both induces HIF-1α and impairs autophagic flux in macrophages. Using small interfering RNA-mediated knock-down and overexpression of HIF-1α in macrophages, we demonstrated that PA impairs autophagy via HIF-1α. We found that HIF-1α mediates NF-κB activation and MCP-1 production and that HIF-1α-mediated impairment of macrophage autophagy increases IL-1β production, contributing to MCD diet-induced NASH. Conclusion: Palmitic acid impairs autophagy via HIF-1α activation in macrophages. HIF-1α and impaired autophagy are present in NASH in vivo in mouse macrophages and in human blood monocytes. We identified that HIF-1α activation and decreased autophagic flux stimulate inflammation in macrophages through upregulation of NF-κB activation. These results suggest that macrophage activation in NASH involves a complex interplay between HIF-1α and autophagy as these pathways promote proinflammatory overactivation in MCD diet-induced NASH.

Autophagy in Ovarian Follicular Development and Atresia

Autophagy is a mechanism that exists in all eukaryotes under a variety of physiological and pathological conditions. In the mammalian ovaries, less than 1% of follicles ovulate, whereas the remaining 99% undergo follicular atresia. Autophagy and apoptosis have been previously found to be involved in the regulation of both primordial follicular development as well as atresia. The relationship between autophagy, follicular development, and atresia have been summarized in this review with the aim to obtain a more comprehensive understanding of the role played by autophagy in follicular development and atresia.

Diet Modulation Restores Autophagic Flux in Damaged Skeletal Muscle Cells

OBJECTIVES

Autophagy is a physiological and highly regulated mechanism, crucial for cell homeostasis maintenance. Its impairment seems to be involved in the onset of several diseases, including muscular dystrophies, myopathies and sarcopenia. According to few papers, chemotherapeutic drug treatment is able to trigger side effects on skeletal muscle tissue and, among these, a defective autophagic activation, which leads to the persistence of abnormal organelles within cells and, finally, to myofiber degeneration. The aim of this work is to find a strategy, based on diet modulation, to prevent etoposide-induced damage, in a model of in vitro skeletal muscle cells.

METHODS

Glutamine supplementation and nutrient deprivation have been chosen as pre-treatments to counteract etoposide effect, a chemotherapeutic drug known to induce oxidative stress and cell death. Cell response has been evaluated by means of morpho-functional, cytofluorimetric and molecular analyses.

RESULTS

Etoposide treated cells, if compared to control, showed dysfunctional mitochondria presence, ER stress and lysosomal compartment damage, confirmed by molecular investigations.

CONCLUSIONS

Interestingly, both dietary approaches were able to rescue myofiber from etoposide-induced damage. Glutamine supplementation, in particular, seemed to be a good strategy to preserve cell ultrastructure and functionality, by preventing the autophagic impairment and partially restoring the normal lysosomal activity, thus maintaining skeletal muscle homeostasis.

Visual Defects and Ageing

Many diseases are related to age, among these neurodegeneration is particularly important. Alzheimer's disease Parkinson's and Glaucoma have many common pathogenic events including oxidative damage, Mitochondrial dysfunction, endothelial alterations and changes in the visual field. These are well known in the case of glaucoma, less in the case of neurodegeneration of the brain. Many other molecular aspects are common, such as the role of endoplasmic reticulum autophagy and neuronal apoptosis while others have been neglected due to lack of space such as inflammatory cytokine or miRNA. Moreover, the loss of specific neuronal populations, the induction of similar mechanisms of cell injury and the deposition of protein aggregates in specific anatomical areas are very similar events between these diseases. Intracellular and/or extracellular accumulation of protein aggregates is a key feature of many neurodegenerative disorders. The existence of abnormal protein aggregates has been documented in the RGCs of glaucomatous patients such as the anomalous Tau protein or the β-amyloid accumulations. Intra-cell catabolic processes also appear to be common in both glaucoma and neurodegeneration. They also help us to understand how the basis between these diseases is common and how the visual aspects can be a serious problem for those who are affected.

Neuronal autophagy aggravates microglial inflammatory injury by downregulating CX3CL1/fractalkine after ischemic stroke

Ischemic stroke often induces excessive neuronal autophagy, resulting in brain damage; meanwhile, inflammatory responses stimulated by ischemia exacerbate neural injury. However, interactions between neuronal autophagy and microglial inflammation following ischemic stroke are poorly understood. CX3CL1/fractalkine, a membrane-bound chemokine expressed on neurons, can suppress microglial inflammation by binding to its receptor CX3CR1 on microglia. In the present study, to investigate whether autophagy could alter CX3CL1 expression on neurons and consequently change microglial inflammatory activity, middle cerebral artery occlusion (MCAO) was established in Sprague-Dawley rats to model ischemic stroke, and tissues from the ischemic penumbra were obtained to evaluate autophagy level and microglial inflammatory activity. MCAO rats were administered 3-methyladenine (autophagy inhibitor) or Tat-Beclin 1 (autophagy inducer). Western blot assays were conducted to quantify expression of Beclin-1, nuclear factor kappa B p65 (NF-κB), light chain 3B (LC3B), and CX3CL1 in ischemic penumbra. Moreover, immunofluorescence staining was performed to quantify numbers of LC3B-, CX3CL1-, and Iba-1-positive cells in ischemic penumbra. In addition, enzyme linked immunosorbent assays were utilized to analyze concentrations of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 1 beta (IL-1β), and prostaglandin E2 (PGE2). A dry/wet weight method was used to detect brain water content, while 2,3,5,-triphenyltetrazolium chloride staining was utilized to measure infarct volume. The results demonstrated that autophagy signaling (Beclin-1 and LC3B expression) in penumbra was prominently activated by MCAO, while CX3CL1 expression on autophagic neurons was significantly reduced and microglial inflammation was markedly activated. However, after inhibition of autophagy signaling with 3-methyladenine, CX3CL1 expression on neurons was obviously increased, whereas Iba-1 and NF-κB expression was downregulated; TNF-α, IL-6, IL-1β, and PGE2 levels were decreased; and cerebral edema was obviously mitigated. In contrast, after treatment with the autophagy inducer Tat-Beclin 1, CX3CL1 expression on neurons was further reduced; Iba-1 and NF-κB expression was increased; TNF-α, IL-6, IL-1β, and PGE2 levels were enhanced; and cerebral edema was aggravated. Our study suggests that ischemia-induced neuronal autophagy facilitates microglial inflammatory injury after ischemic stroke, and the efficacy of this process may be associated with downregulated CX3CL1 expression on autophagic neurons.

Association between autophagy and inflammation in patients with rheumatoid arthritis receiving biologic therapy

Background

Increasing evidence indicates a pathogenic role of deregulated autophagy in rheumatoid arthritis (RA). We examined the relationship between autophagy and inflammatory parameters in patients with RA receiving biologic therapy.

Methods

In 72 patients with RA and 20 healthy control subjects (HC), autophagosome levels were determined by the mean fluorescence intensity (MFI) of autophagosomotropic dye incorporated into circulating immune cells, and p62 expression levels in immune cells were measured by flow cytometry. We used immunoblotting to examine protein expression of LC3-II and p62 in peripheral blood mononuclear cells.

Results

Patients with RA had significantly higher levels of autophagosome reflected by MFI of Cyto-ID in circulating lymphocytes, monocytes, and granulocytes (median values, 3.6, 11.6, and 64.8, respectively) compared with HC (1.9, 6.0, and 35.8; respectively) (all p < 0.001). p62 MFI levels in lymphocytes and granulocytes from patients with RA (17.1 and 8.6, respectively) were significantly lower than those in the corresponding cells from HC (20.2, p < 0.05; and 13.1, p < 0.001, respectively). Significantly higher levels of LC3-II protein expression in contrast to lower p62 protein levels were observed in patients with RA than in HC. The autophagosome levels in immune cells were significantly correlated with inflammatory parameters in patients with RA, and they were significantly decreased with disease remission after treatment with tumor necrosis factor-α inhibitors or interleukin-6 receptor inhibitor.

Conclusions

Elevated autophagy with significant correlation to inflammation suggests the involvement of autophagy in RA pathogenesis. The effectiveness of biologic therapy might be partly related to the downregulation of autophagy expression.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1763-0) contains supplementary material, which is available to authorized users.

Autophagy, EVs, and Infections: A Perfect Question for a Perfect Time

Autophagy, a highly conserved process, serves to maintain cellular homeostasis in response to an extensive variety of internal and external stimuli. The classic, or canonical, pathway of autophagy involves the coordinated degradation and recycling of intracellular components and pathogenic material. Proper regulation of autophagy is critical to maintain cellular health, as alterations in the autophagy pathway have been linked to the progression of a variety of physiological and pathological conditions in humans, namely in aging and in viral infection. In addition to its canonical role as a degradative pathway, a more unconventional and non-degradative role for autophagy has emerged as an area of increasing interest. This process, known as secretory autophagy, is gaining widespread attention as many viruses are believed to use this pathway as a means to release and spread viral particles. Moreover, secretory autophagy has been found to intersect with other intracellular pathways, such as the biogenesis and secretion of extracellular vesicles (EVs). Here, we provide a review of the current landscape surrounding both degradative autophagy and secretory autophagy in relation to both aging and viral infection. We discuss their key features, while describing their interplay with numerous different viruses (i.e. hepatitis B and C viruses, Epstein-Barr virus, SV40, herpesviruses, HIV, chikungunya virus, dengue virus, Zika virus, Ebola virus, HTLV, Rift Valley fever virus, poliovirus, and influenza A virus), and compare secretory autophagy to other pathways of extracellular vesicle release. Lastly, we highlight the need for, and emphasize the importance of, more thorough methods to study the underlying mechanisms of these pathways to better advance our understanding of disease progression.

Atorvastatin reverses the dysfunction of human umbilical vein endothelial cells induced by angiotensin II

Statins exert pleiotropic effects on endothelial cells, in addition to lowering cholesterol. This study evaluated angiotensin II (Ang II)-induced dysfunction in human umbilical vein endothelial cells (HUVECs), and the effects of atorvastatin (Ator) on induced HUVECs in vitro. The cytotoxicity of Ang II and Ator was determined by the MTT assay. A series of cellular responses were screened, including oxidative stress, cellular apoptosis, inflammatory response, autophagy, expression of endothelial nitric oxide synthase and the angiogenic function of HUVECs. Ator returned these cellular responses to a normal level. The present study also examined cellular organelle dysfunction. In HUVECs, Ang II triggered mitochondrial damage, as demonstrated by a decreased mitochondrial membrane potential, while Ator attenuated this Ang II-induced damage. The observed cellular dysfunction may cause endothelial senescence due to excessive cell injury. The current study examined several aging markers, which revealed that these disorders of cellular functions triggered endothelial senescence, which was delayed by Ator. Ator also suppressed Ang II-induced angiogenesis damage. The data presented in this study strongly suggested that Ang II induced a series of processes that lead to cellular dysfunction in HUVECs, including oxidative stress, inflammation, and mitochondrial damage, leading to apoptosis and endothelial senescence. However, Ator significantly reversed these effects and modulated intracellular stability. The present study indicated that Ator serves an antagonistic role against HUVEC dysfunction and may potentially prevent several diseases, including coronary disease and atherosclerosis, by maintaining cellular homeostasis.

Activation of CD137 Signaling Enhances Vascular Calcification through c-Jun N-Terminal Kinase-Dependent Disruption of Autophagic Flux

Background

Vascular calcification is widespread and clinically significant, contributing to substantial morbidity and mortality. Calcifying vascular cells are partly derived from local vascular smooth muscle cells (VSMCs), which can undergo chondrogenic or osteogenic differentiation under inflammatory environment. Recently, we have found activation of CD137 signaling accelerated vascular calcification. However, the underlying mechanism remains unknown. This study aims to identify key mediators involved in CD137 signaling-induced vascular calcification in vivo and in vitro.

Methods

Autophagy flux was measured through mRFP-GFP-LC3 adenovirus and transmission electron microscopy. Von Kossa assay and alkaline phosphatase (ALP) activity were used to observe calcification in vivo and in vitro, respectively. Autophagosome-containing vesicles were collected and identified by flow cytometry and Western blot. Autophagy or calcification-associated targets were measured by Western blot, quantitative real-time PCR, and immunohistochemistry.

Results

Treatment with the agonist-CD137 displayed c-Jun N-terminal kinase- (JNK-) dependent increase in the expression of various markers of autophagy and the number of autophagosomes relative to the control group. Autophagy flux experiments suggested that agonist-CD137 blocked the fusion of autophagosomes with lysosomes in cultured VSMCs. Calcium deposition, ALP activity, and the expression of calcification-associated proteins also increased in agonist-CD137 group compared with anti-CD137 group, which could be recovered by autophagy stimulator rapamycin. Autophagosome-containing vesicles collected from agonist-CD137 VSMCs supernatant promoted VSMC calcification.

Conclusion

The present study identified a new pathway in which CD137 promotes VSMC calcification through the activation of JNK signaling, subsequently leading to the disruption of autophagic flux, which is responsible for CD137-induced acceleration of vascular calcification.

Autophagy upregulation as a possible mechanism of arsenic induced diabetes

The key features of type 2 diabetes mellitus (T2DM) caused by high fat diet (HFD) in combination with arsenic (As) exposure (pronounced glucose intolerance despite a significant decrease in insulin resistance) are different from those expected for T2DM. Autophagy has been considered as a possible link between insulin resistance and obesity. Therefore in this study, we utilized autophagy gene expression profiling via real-time RT-PCR array analysis in livers of NMRI mice exposed to an environmentally relevant and minimally cytotoxic concentration of arsenite (50 ppm) in drinking water while being fed with a HFD for 20 weeks. Out of 84 genes associated with autophagy under study, 21 genes were related to autophagy machinery components of which 13 genes were downregulated when HDF diet was applied. In this study, for the first time, it was shown that the exposure to arsenic in the livers of mice chronically fed with HFD along with increased oxidative stress resulted in the restoration of autophagy [upregulation of genes involved in the early phase of phagophore formation, phagophore expansion and autophagosome-lysosome linkage stages]. Considering the role of arsenic in the induction of autophagy; it can be argued that reduced insulin resistance in HFD - As induced diabetes may be mediated by autophagy upregulation.

Resolution of inflammation and mood disorders

Relationship between mood disorders and inflammation is now well-documented, although molecular mechanisms are not understood. Previously mostly pro-inflammatory cytokines of immune system (IL-6, TNF, etc.) were taken into account. However, recent understanding of resolution of inflammation as an active process drew attention to mediators of resolution, which include both proteins and ω-3 and ω-6 polyunsaturated fatty acids derivatives (resolvins, cyclopentenone prostaglandins, etc.). This review takes into account new data on resolution of inflammation and action of mediators of resolution in models of depression. New facts and ideas about mechanisms of chronic inflammation onset are considered in relation to mood disorders. Basic control mechanisms of inflammation at the cellular level and the role of resolution substances in regulation of depression and other mood disorders are discussed. Signaling systems of innate immunity located in non-immune cells and their ability to generate substances that affect an onset of depression are reviewed. A novel hypothesis of depression as a type of abnormal resolution is proposed.

Protective Effects of Nintedanib against Polyhexamethylene Guanidine Phosphate-Induced Lung Fibrosis in Mice

Nintedanib (NDN), a tyrosine kinase inhibitor, has been shown to have anti-tumor, anti-inflammatory, and anti-fibrotic effects in several reports. We investigated the protective effects of NDN against polyhexamethylene guanidine phosphate (PHMG)-induced lung fibrosis in mice. The following three experimental groups were evaluated: (1) vehicle control; (2) PHMG (1.1 mg/kg); and (3) PHMG & NDN (60 mg/kg). PHMG induced pulmonary inflammation and fibrosis by intratracheal instillation in mice. In contrast, NDN treatment effectively alleviated the PHMG induced lung injury, and attenuated the number of total cells and inflammatory cells in the bronchoalveolar lavage fluid, including the fibrotic histopathological changes, and also reduced the hydroxyproline content. NDN also significantly decreased the expression of inflammatory cytokines and fibrotic factors, and the activation of the NLRP3 inflammasome in lung tissues. These results suggest that NDN may mitigate the inflammatory response and development of pulmonary fibrosis in the lungs of mice treated with PHMG.

Autophagy and proinflammatory cytokines: Interactions and clinical implications

Autophagy is a ubiquitous cellular process that regulates cell growth, survival, development and death. Its process is closely associated with diverse conditions, such as liver diseases, neurodegenerative diseases, myopathy, heart diseases, cancer, immunization, and inflammatory diseases. Thus, understanding the modulation of autophagy may provide novel insight into potential therapeutic targets. Autophagy is closely intertwined with inflammatory and immune responses, and cytokines may help mediate this interaction. Autophagy has been shown to regulate, and be regulated by, a wide range of proinflammatory cytokines. This review aims to summarize recent progress in elucidating the interplay between autophagy and proinflammatory cytokines, including IFN-γ, TNF-α, IL-17, and cytokines of the IL-1 family (e.g., IL-1α, IL-1β, IL-33, and IL-36).

Clinical Mycobacterium abscessus strain inhibits autophagy flux and promotes its growth in murine macrophages

Autophagy is known to be a vital homeostatic defense process that controls mycobacterial infection. However, the relationship between autophagy response and the virulence of Mycobacterium abscessus strain UC22 has not been reported. Here, we demonstrate that M. abscessus induces autophagy and inhibits autophagy flux in murine macrophages. Further, the rough variant of M. abscessus, UC22 that is a highly virulent clinical isolate, significantly inhibited autophagic flux than the smooth variant of M. abscessus ATCC 19977. In addition, it was noticed that the intracellular survival of UC22 is significantly enhanced by blocking the autophagosome-lysosome fusion in macrophages compared to the smooth variant. However, Mycobacterium smegmatis did not block autophagy flux in murine macrophages. Besides, we confirmed that the lipid components of M. abscessus UC22 play a role in autophagosome formation. These data suggest that the virulent M. abscessus might be able to survive and grow within autophagosomes by preventing the autophagosome-lysosome fusion and their clearance from the cells.

Autophagy in health and disease: A comprehensive review

Autophagy, a conserved catabolic process, plays an immensely significant role in a variety of diseases. However, whether it imparts a protective function in diseases remains debatable. During aging, autophagy gradually subsides, manifested by the reduced formation of autophagic vacuoles and improper fusion of these vacuoles with the lysosomes. Similarly, in neurodegenerative disorders, accumulation of tau and synuclein proteins has been attributed to the decline in the autophagic removal of proteins. Equivalently, lysosomal disorders show an impairment of the autophagic process leading to the accumulation of lipid molecules within lysosomes. On the other hand, activation of the autophagic pathway has also proved beneficial in evading various foreign pathogens, thereby contributing to the innate immunity. In the context of cancer, autophagy has shown to play a puzzling role where it serves as a tumor suppressor during initial stages but later protects the tumor cells from the immune system defense mechanisms. Similarly, muscular and heart disorders have been shown to be positively and negatively regulated by autophagy, respectively. In the present review, we, therefore, present a comprehensive review on the role of autophagy in various diseases and their corresponding outcomes.

Differential Expression of microRNAs in Peripheral Blood Mononuclear Cells Identifies Autophagy and TGF-Beta-Related Signatures Aberrantly Expressed in Inflammatory Bowel Disease

BACKGROUND AND AIMS

MicroRNAs [miRNAs] have emerged as important regulators in inflammatory bowel disease [IBD]. This study investigated differential expression of miRNAs across clinical phenotypes in a well-characterized cohort of IBD patients and healthy controls [HCs].

METHODS

A cohort of Crohn's disease [CD] and ulcerative colitis [UC] patients and HCs was prospectively accrued. Total RNA was extracted from peripheral blood mononuclear cells for all subjects. miRNA expression was measured using NanoString technologies. The subjects were stratified according to disease activity and location. Statistical significance was assessed per miRNA across outcomes and corrected for multiple testing. miRNA regulation of transcription of important results was confirmed in vitro by a dual luciferase reporter assay and autophagy function was evaluated using immunofluorescence imaging of LC3 puncta in HeLa cells.

RESULTS

In total, 120 subjects were enrolled. Seventy-four miRNAs were differentially expressed across CD, UC and HCs. Comparing quiescent CD [CDq] with HCs we found ten miRNAs upregulated in CDq. When comparing colonic CD [CCD] to UC, seven miRNAs were upregulated in CCD. The most differentially expressed miRNA in CCD vs UC was miR-874-3p, and we showed its possible utility as a biomarker of differential diagnosis. We showed miR-874-3p targets ATG16L1 and reduces its expression in vitro. An miR-874-3p mimic dysregulates autophagy by a reduction of LC3 in vitro.

CONCLUSIONS

We identified unique miRNA signatures expressed in distinct IBD phenotypes. These associations highlight pathways dysregulated by aberrant miRNA expression, revealing possible mechanisms underlying the pathophysiology of IBD, but also suggest a cluster of miRNAs as readily accessible biomarkers to aid in differential diagnosis.

Autophagy and LAP in the Fight against Fungal Infections: Regulation and Therapeutics

Phagocytes fight fungi using canonical and noncanonical, also called LC3-associated phagocytosis (LAP), autophagy pathways. However, the outcomes of autophagy/LAP in shaping host immune responses appear to greatly vary depending on fungal species and cell types. By allowing efficient pathogen clearance and/or degradation of inflammatory mediators, autophagy proteins play a broad role in cellular and immune homeostasis during fungal infections. Indeed, defects in autophagic machinery have been linked with aberrant host defense and inflammatory states. Thus, understanding the molecular mechanisms underlying the relationship between the different forms of autophagy may offer a way to identify drugable molecular signatures discriminating between selective recognition of cargo and host protection. In this regard, IFN-γ and anakinra are teaching examples of successful antifungal agents that target the autophagy machinery. This article provides an overview of the role of autophagy/LAP in response to fungi and in their infections, regulation, and therapeutic exploitation.

TREM-1 Inhibition Restores Impaired Autophagy Activity and Reduces Colitis in Mice

BACKGROUND AND AIMS

Triggering receptor expressed on myeloid cells-1 [TREM-1] is known to amplify inflammation in several diseases. Autophagy and endoplasmic reticulum [ER] stress, which activate the unfolded protein response [UPR], are closely linked and defects in these pathways contribute to the pathogenesis of inflammatory bowel disease [IBD]. Both autophagy and UPR are deeply involved in host-microbiota interactions for the clearance of intracellular pathogens, thus contributing to dysbiosis. We investigated whether inhibition of TREM-1 would prevent aberrant inflammation by modulating autophagy and ER stress and preventing dysbiosis.

METHODS

An experimental mouse model of colitis was established by dextran sulphate sodium treatment. TREM-1 was inhibited, either pharmacologically by LR12 peptide or genetically with Trem-1 knock-out [KO] mice. Colon tissues and faecal pellets of control and colitic mice were used. Levels of macroautophagy, chaperone-mediated autophagy [CMA], and UPR proteins were evaluated by western blotting. The composition of the intestinal microbiota was assessed by MiSeq sequencing in both LR12-treated and KO animals.

RESULTS

We confirmed that inhibition of TREM-1 attenuates the severity of colitis clinically, endoscopically and histologically. We observed an increase in macroautophagy [ATG1/ULK-1, ATG13, ATG5, ATG16L1, and MAP1LC3-I/II] and in CMA [HSPA8 and HSP90AA1], whereas there was a decrease in the UPR [PERK, IRE-1α, and ATF-6α] protein expression levels in TREM-1 inhibited colitic mice. TREM-1 inhibition prevented dysbiosis.

CONCLUSIONS

TREM-1 may represent a novel drug target for the treatment of IBD, by modulating autophagy activity and ER stress.

Up-regulated autophagy: as a protective factor in adipose tissue of WOKW rats with metabolic syndrome

BACKGROUND

Wistar Ottawa Karlsburg W (RT1u) rats (WOKW) are a model of the metabolic syndrome (MetS). Adipose tissue (AT) and peripheral nerves of WOKW rats exhibit up-regulated autophagy and inflammation corresponding with decreased apoptosis rate. The aim of this study was to characterize AT in WOKW rats in relation to autophagic activity.

METHODS

mRNA and protein expression of adiponectin, pro-inflammatory and pro-apoptotic markers including MCP1, TNFα, cleaved caspase-3 and RNF157, a new candidate gene regulated through autophagy, were analyzed in adipocytes isolated from visceral and subcutaneous AT of 5-month old WOKW rats with MetS and LEW.1W controls in response to pharmacological inhibition of autophagy. Immunohistochemistry was performed to detect adiponectin and RNF157 protein in cultured adipocytes.

RESULTS

Inhibition of autophagy by LY294002 was associated with a fourfold up-regulation of adiponectin expression and a decrease of RNF157 protein and pro-inflammatory markers-MCP-1 and TNFα predominantly in visceral adipocytes of obese WOKW rats compared to LEW.1W rats. Moreover, inhibition of autophagic activity correlates with an activation of cleaved caspase-3 apoptotic signaling pathway.

CONCLUSIONS

Up-regulated autophagy in obese WOKW rats contributes to the regulation of visceral AT function and involves an altered balance between pro-inflammatory and protective adipokine expression. Our data suggest that activation of AT autophagy protects against adipocyte apoptosis at least under conditions of obesity related MetS in WOKW rats.

Impaired autophagic flux and its related inflammation in patients with adult-onset Still's disease

The pathogenic role of autophagic immune regulation in adult-onset Still’s disease (AOSD) is unclear. We investigated the relative levels of autophagy in AOSD patients and healthy controls, its association with disease activity or course, and the change in autophagy after 6 months of therapy. Autophagosome levels were determined from the mean fluorescence intensity of autophagosomotropic dye incorporated into circulating immune cells. The fluorescent signal from lymphocytes, monocytes, and granulocytes from AOSD patients was greater than from controls. Levels of p62 fluorescence measured using flow cytometry in lymphocytes and granulocytes from AOSD patients was greater than in the corresponding cells from healthy controls. Expression of Atg5 and LC3-II mRNA and protein levels of p62 and LC3-II were elevated in AOSD patients. Moreover, AOSD activity scores correlated positively with autophagosome levels in monocytes and granulocytes, p62 levels in circulating immune cells, and levels of Beclin-1, Atg5, and LC3-II mRNA. Autophagosome levels and Atg mRNA expression decreased with disease remission in AOSD patients. Elevated autophagosome formation and p62 levels suggest impaired autophagic flux in AOSD.

Iraqi propolis increases degradation of IL-1β and NLRC4 by autophagy following Pseudomonas aeruginosa infection

Autophagy is a cellular process for maintaining cellular homeostasis. This process can be induced by different factors, such as immune stimuli and pathogen-associated molecules. Autophagy has an important role in the control of IL-1β secretion by macrophages and other cell types. In present study, we describe a novel role for Iraqi propolis affecting autophagy in controlling the secretion of IL-1β in bone-marrow macrophages (BMDMs). After infection with Pseudomonas aeruginosa in the presence of propolis, the degradation of IL-1β was induced, and the activity of inflammasome was reduced. Iraqi propolis-induced autophagy in in vitro and in vivo models decreased the levels of IL-1β and caspase-1. Results indicated that IL-1β pathway production is regulated by autophagy via two different novel mechanisms, namely, regulation of the activation of NLRC4 inflammasome and IL-1β targeting for lysosomal degradation.

Systems Approach Reveals Nuclear Factor Erythroid 2-Related Factor 2/Protein Kinase R Crosstalk in Human Cutaneous Leishmaniasis

Leishmania parasites infect macrophages, causing a wide spectrum of human diseases, from cutaneous to visceral forms. In search of novel therapeutic targets, we performed comprehensive in vitro and ex vivo mapping of the signaling pathways upstream and downstream of antioxidant transcription factor [nuclear factor erythroid 2-related factor 2 (Nrf2)] in cutaneous leishmaniasis (CL), by combining functional assays in human and murine macrophages with a systems biology analysis of in situ (skin biopsies) CL patient samples. First, we show the PKR pathway controls the expression and activation of Nrf2 in Leishmania amazonensis infection in vitro. Nrf2 activation also required PI3K/Akt signaling and autophagy mechanisms. Nrf2- or PKR/Akt-deficient macrophages exhibited increased levels of ROS/RNS and reduced expression of Sod1 Nrf2-dependent gene and reduced parasite load. L. amazonensis counteracted the Nrf2 inhibitor Keap1 through the upregulation of p62 via PKR. This Nrf2/Keap1 observation was confirmed in situ in skin biopsies from Leishmania-infected patients. Next, we explored the ex vivo transcriptome in CL patients, as compared to healthy controls. We found the antioxidant response element/Nrf2 signaling pathway was significantly upregulated in CL, including downstream target p62. In silico enrichment analysis confirmed upstream signaling by interferon and PI3K/Akt, and validated our in vitro findings. Our integrated in vitro, ex vivo, and in silico approach establish Nrf2 as a central player in human cutaneous leishmaniasis and reveal Nrf2/PKR crosstalk and PI3K/Akt pathways as potential therapeutic targets.

Autophagy and inflammation

Autophagy is a homeostatic mechanism involved in the disposal of damaged organelles, denatured proteins as well as invaded pathogens through a lysosomal degradation pathway. Recently, increasing evidences have demonstrated its role in both innate and adaptive immunity, and thereby influence the pathogenesis of inflammatory diseases. The detection of autophagy machinery facilitated the measurement of autophagy during physiological and pathophysiological processes. Autophagy plays critical roles in inflammation through influencing the development, homeostasis and survival of inflammatory cells, including macrophages, neutrophils and lymphocytes; effecting the transcription, processing and secretion of a number of cytokines, as well as being regulated by cytokines. Recently, autophagy-dependent mechanisms have been studied in the pathogenesis of several inflammatory diseases, including infectious diseases, Crohn’s disease, cystic fibrosis, pulmonary hypertension, chronic obstructive pulmonary diseases and so on. These studies suggested that modulation of autophagy might lead to therapeutic interventions for diseases associated with inflammation. Here we highlight recent advances in investigating the roles of autophagy in inflammation as well as inflammatory diseases.

Mitochondria, Bioenergetics and Excitotoxicity: New Therapeutic Targets in Perinatal Brain Injury

Injury to the fragile immature brain is implicated in the manifestation of long-term neurological disorders, including childhood disability such as cerebral palsy, learning disability and behavioral disorders. Advancements in perinatal practice and improved care mean the majority of infants suffering from perinatal brain injury will survive, with many subtle clinical symptoms going undiagnosed until later in life. Hypoxic-ischemia is the dominant cause of perinatal brain injury, and constitutes a significant socioeconomic burden to both developed and developing countries. Therapeutic hypothermia is the sole validated clinical intervention to perinatal asphyxia; however it is not always neuroprotective and its utility is limited to developed countries. There is an urgent need to better understand the molecular pathways underlying hypoxic-ischemic injury to identify new therapeutic targets in such a small but critical therapeutic window. Mitochondria are highly implicated following ischemic injury due to their roles as the powerhouse and main energy generators of the cell, as well as cell death processes. While the link between impaired mitochondrial bioenergetics and secondary energy failure following loss of high-energy phosphates is well established after hypoxia-ischemia (HI), there is emerging evidence that the roles of mitochondria in disease extend far beyond this. Indeed, mitochondrial turnover, including processes such as mitochondrial biogenesis, fusion, fission and mitophagy, affect recovery of neurons after injury and mitochondria are involved in the regulation of the innate immune response to inflammation. This review article will explore these mitochondrial pathways, and finally will summarize past and current efforts in targeting these pathways after hypoxic-ischemic injury, as a means of identifying new avenues for clinical intervention.

Mitochondrial carriers in inflammation induced by bacterial endotoxin and cytokines

Significant metabolic changes occur in the shift from resting to activated cellular status in inflammation. Thus, changes in expression of a large number of genes and extensive metabolic reprogramming gives rise to acquisition of new functions (e.g. production of cytokines, intermediates for biosynthesis, lipid mediators, PGE, ROS and NO). In this context, mitochondrial carriers, which catalyse the transport of solute across mitochondrial membrane, change their expression to transport mitochondrially produced molecules, among which citrate and succinate, to be used as intracellular signalling molecules in inflammation. This review summarises the mitochondrial carriers studied so far that are, directly or indirectly, involved in inflammation.

Stress-induced cellular responses and cell death mechanisms during inflammatory cholangiopathies

Various cellular responses including apoptosis, necrosis, autophagy and cellular senescence are involved in the pathogenesis of inflammatory cholangiopathies, such as primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and biliary atresia (BA). For example, dysregulated autophagy may play a role in abnormal expression of mitochondrial antigens and following autoimmune pathogenesis in bile duct lesions in PBC. Recently, new types of regulated cell death including necroptosis, parthanatos, pyroptosis, immunogenic cell death are the subject of numerous reports and they may play roles in pathogenesis of liver diseases, such as nonalcoholic steatohepatitis. Although there have been few studies on these new types of regulated cell death in inflammatory cholangiopathies, so far, they may play important roles in the pathophysiology of inflammatory cholangiopathies. Further studies on new types of regulated cell death are mandatory, since they could be targets of new therapeutic approaches for these diseases.

Polymorphisms in autophagy genes and active pulmonary tuberculosis susceptibility in Romania

Autophagy, a homeostatic process involved in nutrient regeneration and immune responses, may be involved in intracellular killing of M. tuberculosis. Several studies linked variation in autophagy genes with susceptibility to pulmonary tuberculosis, but others did not confirm these findings.

We genotyped single nucleotide polymorphisms (SNPs) in the ATG5 (rs2245214, c.574-12777G>C) and NOD2 (rs2066844, c.2104C>T) genes for 256 pulmonary tuberculosis patients and 330 unrelated healthy controls in Romania. Both SNPs have been reported as relevant for the autophagy process and potentially for susceptibility to active pulmonary tuberculosis.

In our study, the polymorphisms in ATG5 and NOD2 were not associated with tuberculosis. This suggests that the two genetic variants we focused on are not related to the risk for developing active TB in a Romanian population.

Human vaginal epithelial cells augment autophagy marker genes in response to Candida albicans infection

PROBLEM

Autophagy plays an important role in clearance of intracellular pathogens. However, no information is available on its involvement in vaginal infections such as vulvo-vaginal candidiasis (VVC). VVC is intimately associated with the immune status of the human vaginal epithelial cells (VECs). The objective of our study is to decipher if autophagy process is involved during Candida albicans infection of VECs.

METHODS OF STUDY

In this study, C. albicans infection system was established using human VEC line (VK2/E6E7). Infection-induced change in the expression of autophagy markers like LC3 and LAMP-1 were analyzed by RT-PCR, q-PCR, Western blot, immunofluorescence and transmission electron microscopy (TEM) studies were carried out to ascertain the localization of autophagosomes. Multiplex ELISA was carried out to determine the cytokine profiles.

RESULTS

Analysis of LC3 and LAMP-1 expression at mRNA and protein levels at different time points revealed up-regulation of these markers 6 hours post C. albicans infection. LC3 and LAMP-1 puncti were observed in infected VECs after 12 hours. TEM studies showed C. albicans entrapped in autophagosomes. Cytokines-TNF-α and IL-1β were up-regulated in culture supernatants of VECs at 12 hours post-infection.

CONCLUSION

The results suggest that C. albicans invasion led to the activation of autophagy as a host defense mechanism of VECs.

IL-17-mediated mitochondrial dysfunction impairs apoptosis in rheumatoid arthritis synovial fibroblasts through activation of autophagy

Fibroblast-like synoviocytes (FLSs) are a major cell population of the pannus that invades cartilage and bone in rheumatoid arthritis (RA). FLS resistance to apoptosis is a major characteristic of RA. The aims of this study were to investigate the effects of interleukin-17 (IL-17) and IL-17-producing T helper (Th17) cells on resistance to apoptosis in FLSs from RA patients (RA FLSs) and their roles in mitochondrial dysfunction and autophagy. Mitochondrial function was assessed in RA FLSs and FLSs from osteoarthritis patients (OA FLSs). FLSs were treated with IL-17 and their morphological features, respiratory level and mitochondrial gene expression were measured. The effects of IL-17 and Th17 cells on the relationship between autophagy and apoptosis were evaluated by measuring the expression of apoptosis-related genes using sodium nitroprusside or 3-methyladenine. The mitochondria of FLSs isolated from RA and osteoarthritis patients displayed different morphological and physiological features. RA FLSs exhibited greater autophagosome formation and greater dysfunction of mitochondrial respiration compared with OA FLSs. IL-17 induced mitochondrial dysfunction and autophagosome formation in RA FLSs, suggesting that they were resistant to apoptosis. Autophagy-related antiapoptosis induced by IL-17 was restored by inhibition of autophagy, suggesting a relationship between mitochondrial dysfunction and cell survival in RA FLSs. Th17 cells and IL-17 increased autophagy of RA FLSs by causing mitochondrial dysfunction. Our findings suggest that, in RA, interactions between RA FLSs and Th17 cells may be involved in the tumorous growth of FLSs and the formation of pannus in joints.

Adipocyte Fatty Acid Binding Protein Potentiates Toxic Lipids-Induced Endoplasmic Reticulum Stress in Macrophages via Inhibition of Janus Kinase 2-dependent Autophagy

Lipotoxicity is implicated in the pathogenesis of obesity-related inflammatory complications by promoting macrophage infiltration and activation. Endoplasmic reticulum (ER) stress and adipocyte fatty acid binding protein (A-FABP) play key roles in obesity and mediate inflammatory activity through similar signaling pathways. However, little is known about their interplay in lipid-induced inflammatory responses. Here, we showed that prolonged treatment of palmitic acid (PA) increased ER stress and expression of A-FABP, which was accompanied by reduced autophagic flux in macrophages. Over-expression of A-FABP impaired PA-induced autophagy associating with enhanced ER stress and pro-inflammatory cytokine production, while genetic ablation or pharmacological inhibition of A-FABP reversed the conditions. PA-induced expression of autophagy-related protein (Atg)7 was attenuated in A-FABP over-expressed macrophages, but was elevated in A-FABP-deficient macrophages. Mechanistically, A-FABP potentiated the effects of PA by inhibition of Janus Kinase (JAK)2 activity, thus diminished PA-induced Atg7 expression contributing to impaired autophagy and further augmentation of ER stress. These findings suggest that A-FABP acts as autophagy inhibitor to instigate toxic lipids-induced ER stress through inhibition of JAK2-dependent autophagy, which in turn triggers inflammatory responses in macrophages. A-FABP-JAK2 axis may represent an important pathological pathway contributing to obesity-related inflammatory diseases.

Systematic analysis of chromatin interactions at disease associated loci links novel candidate genes to inflammatory bowel disease

BACKGROUND

Genome-wide association studies (GWAS) have revealed many susceptibility loci for complex genetic diseases. For most loci, the causal genes have not been identified. Currently, the identification of candidate genes is predominantly based on genes that localize close to or within identified loci. We have recently shown that 92 of the 163 inflammatory bowel disease (IBD)-loci co-localize with non-coding DNA regulatory elements (DREs). Mutations in DREs can contribute to IBD pathogenesis through dysregulation of gene expression. Consequently, genes that are regulated by these 92 DREs are to be considered as candidate genes. This study uses circular chromosome conformation capture-sequencing (4C-seq) to systematically analyze chromatin-interactions at IBD susceptibility loci that localize to regulatory DNA.

RESULTS

Using 4C-seq, we identify genomic regions that physically interact with the 92 DRE that were found at IBD susceptibility loci. Since the activity of regulatory elements is cell-type specific, 4C-seq was performed in monocytes, lymphocytes, and intestinal epithelial cells. Altogether, we identified 902 novel IBD candidate genes. These include genes specific for IBD-subtypes and many noteworthy genes including ATG9A and IL10RA. We show that expression of many novel candidate genes is genotype-dependent and that these genes are upregulated during intestinal inflammation in IBD. Furthermore, we identify HNF4α as a potential key upstream regulator of IBD candidate genes.

CONCLUSIONS

We reveal many novel and relevant IBD candidate genes, pathways, and regulators. Our approach complements classical candidate gene identification, links novel genes to IBD and can be applied to any existing GWAS data.

Critical Functions of the Lysosome in Cancer Biology

Lysosomes (or lytic bodies) were so named because they contain high levels of hydrolytic enzymes. Lysosome function and dysfunction have been found to play important roles in human disease, including cancer; however, the ways in which lysosomes contribute to tumorigenesis and cancer progression are still being uncovered. Beyond serving as a cellular recycling center, recent evidence suggests that the lysosome is involved in energy homeostasis, generating building blocks for cell growth, mitogenic signaling, priming tissues for angiogenesis and metastasis formation, and activating transcriptional programs. This review examines emerging knowledge of how lysosomal processes contribute to the hallmarks of cancer and highlights vulnerabilities that might be exploited for cancer therapy.

Crosstalk between autophagy and intracellular radiation response (Review)

Autophagy induced by radiation is critical to cell fate decision. Evidence now sheds light on the importance of autophagy induced by cancer radiotherapy. Traditional view considers radiation can directly or indirectly damage DNA which can activate DNA damage the repair signaling pathway, a large number of proteins participating in DNA damage repair signaling pathway such as p53, ATM, PARP1, FOXO3a, mTOR and SIRT1 involved in autophagy regulation. However, emerging recent evidence suggests radiation can also cause injury to extranuclear targets such as plasma membrane, mitochondria and endoplasmic reticulum (ER) and induce accumulation of ceramide, ROS, and Ca2+ concentration which activate many signaling pathways to modulate autophagy. Herein we review the role of autophagy in radiation therapy and the potent intracellular autophagic triggers induced by radiation. We aim to provide a more theoretical basis of radiation-induced autophagy, and provide novel targets for developing cytotoxic drugs to increase radiosensitivity.

Interactions between Autophagy and Inhibitory Cytokines

Autophagy is a degradative pathway that plays an essential role in maintaining cellular homeostasis. Most early studies of autophagy focused on its involvement in age-associated degeneration and nutrient deprivation. However, the immunological functions of autophagy have become more widely studied in recent years. Autophagy has been shown to be an intrinsic cellular defense mechanism in the innate and adaptive immune responses. Cytokines belong to a broad and loose category of proteins and are crucial for innate and adaptive immunity. Inhibitory cytokines have evolved to permit tolerance to self while also contributing to the eradication of invading pathogens. Interactions between inhibitory cytokines and autophagy have recently been reported, revealing a novel mechanism by which autophagy controls the immune response. In this review, we discuss interactions between autophagy and the regulatory cytokines IL-10, transforming growth factor-β, and IL-27. We also mention possible interactions between two newly discovered cytokines, IL-35 and IL-37, and autophagy.

Function of Autophagy in Nonalcoholic Fatty Liver Disease

Autophagy is a lysosomal degradative pathway that functions to promote cell survival by supplying energy in times of stress or by removing damaged organelles and proteins after injury. The involvement of autophagy in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) was first suggested by the finding that this pathway mediates the breakdown of intracellular lipids in hepatocytes and therefore may regulate the development of hepatic steatosis. Subsequent studies have demonstrated additional critical functions for autophagy in hepatocytes and other hepatic cell types such as macrophages and stellate cells that regulate insulin sensitivity, hepatocellular injury, innate immunity, fibrosis, and carcinogenesis. These findings suggest a number of possible mechanistic roles for autophagy in the development of NAFLD and progression to NASH and its complications. The functions of autophagy in the liver, together with findings of decreased hepatic autophagy in association with conditions that predispose to NAFLD such as obesity and aging, suggest that autophagy may be a novel therapeutic target in this disease.

The Use of Kosher Phenotyping for Mapping QTL Affecting Susceptibility to Bovine Respiratory Disease

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in feedlot cattle, caused by multiple pathogens that become more virulent in response to stress. As clinical signs often go undetected and various preventive strategies failed, identification of genes affecting BRD is essential for selection for resistance. Selective DNA pooling (SDP) was applied in a genome wide association study (GWAS) to map BRD QTLs in Israeli Holstein male calves. Kosher scoring of lung adhesions was used to allocate 122 and 62 animals to High (Glatt Kosher) and Low (Non-Kosher) resistant groups, respectively. Genotyping was performed using the Illumina BovineHD BeadChip according to the Infinium protocol. Moving average of -logP was used to map QTLs and Log drop was used to define their boundaries (QTLRs). The combined procedure was efficient for high resolution mapping. Nineteen QTLRs distributed over 13 autosomes were found, some overlapping previous studies. The QTLRs contain polymorphic functional and expression candidate genes to affect kosher status, with putative immunological and wound healing activities. Kosher phenotyping was shown to be a reliable means to map QTLs affecting BRD morbidity.

The Role of Autophagy-Related Proteins in Candida albicans Infections

Autophagy plays an important role in maintaining cell homeostasis by providing nutrients during periods of starvation and removing damaged organelles from the cytoplasm. A marker in the autophagic process is the reversible conjugation of LC3, a membrane scaffolding protein, to double membrane autophagosomes. Recently, a role for LC3 in the elimination of pathogenic bacteria and fungi, including Candida albicans (C. albicans), was demonstrated, but these organisms reside in single membrane phagosomes. This process is distinct from autophagy and is termed LC3-associated phagocytosis (LAP). This review will detail the hallmarks of LAP that distinguish it from classical autophagy and review the role of autophagy proteins in host response to C. albicans and other pathogenic fungi.

KU0063794, a Dual mTORC1 and mTORC2 Inhibitor, Reduces Neural Tissue Damage and Locomotor Impairment After Spinal Cord Injury in Mice

Autophagy is an intracellular catabolic mechanism for the degradation of cytoplasmic constituents in the autophagosomal-lysosomal pathway. This mechanism plays an important role in homeostasis and it is defective in certain diseases. Preceding studies have revealed that autophagy is developing as an important moderator of pathological responses associated to spinal cord injury (SCI) and plays a crucial role in secondary injury initiating a progressive degeneration of the spinal cord. Thus, based on this evidence in this study, we used two different selective inhibitors of mTOR activity to explore the functional role of autophagy in an in vivo model of SCI as well as to determine whether the autophagic process is involved in spinal cord tissue damage. We treated animals with a novel synthetic inhibitor temsirolimus and with a dual mTORC1 and mTORC2 inhibitor KU0063794 matched all with the well-known inhibitor of mTOR the rapamycin. Our results demonstrated that mTOR inhibitors could regulate the neuroinflammation associated to SCI and the results that we obtained evidently demonstrated that rapamycin and temsirolimus significantly diminished the expression of iNOS, COX2, GFAP, and re-established nNOS levels, but the administration of KU0063794 is able to blunt the neuroinflammation better than rapamycin and temsirolimus. In addition, neuronal loss and cell mortality in the spinal cord after injury were considerably reduced in the KU0063794-treated mice. Accordingly, taken together our results denote that the administration of KU0063794 produced a neuroprotective function at the lesion site following SCI, representing a novel therapeutic approach after SCI.

The role of autophagy in modulation of neuroinflammation in microglia

Microglia have multiple functions in regulating homeostasis in the central nervous system (CNS), and microglial inflammation is thought to play a role in the etiology of the neurodegenerative diseases. When endogenous or exogenous stimuli trigger disorders in microenvironmental homeostasis in CNS, microglia critically determine the fate of other neural cells. Recently, it was reported that autophagy might influence inflammation and activation of microglia. Though the interaction between autophagy and macrophages has been reported and reviewed in length, the role of autophagy in microglia has yet to be reviewed. Herein, we will highlight recent advances on the emerging role of autophagy in microglia, focusing on the regulation of autophagy during microglial inflammation, and the possible mechanism involved.

The cooperation between the autophagy machinery and the inflammasome to implement an appropriate innate immune response: do they regulate each other?

Autophagy is originally described as the main catabolic pathway responsible for maintaining intracellular nutritional homeostasis that involves the formation of a unique vacuole, the autophagosome, and the interaction with the endosome-lysosome pathways. This conserved machinery plays a key role in immune-protection against different invaders, including pathogenic bacteria, intracellular parasites, and some viruses like herpes simplex and hepatitis C virus. Importantly, autophagy is linked to a number of human diseases and disorders including neurodegenerative disease, Crohn's disease, type II diabetes, tumorigenesis, cardiomyopathy, and fatty liver disease. On the other hand, inflammasomes are multiprotein platforms stimulated upon several environmental conditions and microbial infection. Once assembled, the inflammasomes mediate the maturation of pro-inflammatory cytokines and promote phagosome-lysosome fusion to sustain an innate immune response. The intersections between autophagy and inflammasome have been observed in various diseases and microbial infections. This review highlights the molecular aspects involved in autophagy and inflammasome interactions during different medical conditions and microbial infections.

MAP1S Protein Regulates the Phagocytosis of Bacteria and Toll-like Receptor (TLR) Signaling

Phagocytosis is a critical cellular process for innate immune defense against microbial infection. The regulation of phagocytosis process is complex and has not been well defined. An intracellular molecule might regulate cell surface-initiated phagocytosis, but the underlying molecular mechanism is poorly understood (1). In this study, we found that microtubule-associated protein 1S (MAP1S), a protein identified recently that is involved in autophagy (2), is expressed primarily in macrophages. MAP1S-deficient macrophages are impaired in the phagocytosis of bacteria. Furthermore, we demonstrate that MAP1S interacts directly with MyD88, a key adaptor of Toll-like receptors (TLRs), upon TLR activation and affects the TLR signaling pathway. Intriguingly, we also observe that, upon TLR activation, MyD88 participates in autophagy processing in a MAP1S-dependent manner by co-localizing with MAP1 light chain 3 (MAP1-LC3 or LC3). Therefore, we reveal that an intracellular autophagy-related molecule of MAP1S controls bacterial phagocytosis through TLR signaling.

Crosstalk Between Macroautophagy and Chaperone-Mediated Autophagy: Implications for the Treatment of Neurological Diseases

Macroautophagy and chaperone-mediated autophagy (CMA) are two important subtypes of autophagy that play a critical role in cellular quality control under physiological and pathological conditions. Despite the marked differences between these two autophagic pathways, macroautophagy and CMA are intimately connected with each other during the autophagy-lysosomal degradation process, in particular, in the setting of neurological illness. Macroautophagy serves as a backup mechanism to removal of malfunctioning proteins (i.e., aberrant α-synuclein) from the cytoplasm when CMA is compromised, and vice versa. The molecular mechanisms underlying the conversation between macroautophagy and CMA are being clarified. Herein, we survey current overviews concentrating on the complex interactions between macroautophagy and CMA, and present therapeutic potentials through utilization and manipulation of macroautophagy-CMA crosstalk in the treatment of neurological diseases.

Contribution of autophagy to antiviral immunity

Although identified in the 1960's, interest in autophagy has significantly increased in the past decade with notable research efforts oriented at understanding as to how this multi-protein complex operates and is regulated. Autophagy is commonly defined as a "self-eating" process evolved by eukaryotic cells to recycle senescent organelles and expired proteins, which is significantly increased during cellular stress responses. In addition, autophagy can also play important roles during human diseases, such as cancer, neurodegenerative and autoimmune disorders. Furthermore, novel findings suggest that autophagy contributes to the host defense against microbial infections. In this article, we review the role of macroautophagy in antiviral immune responses and discuss molecular mechanisms evolved by viral pathogens to evade this process. A role for autophagy as an effector mechanism used both, by innate and adaptive immunity is also discussed.

A possible involvement of endoplasmic reticulum stress in biliary epithelial autophagy and senescence in primary biliary cirrhosis

BACKGROUND

Deregulated autophagy followed by cellular senescence in biliary epithelial cells (BECs) may be closely related to the abnormal expression of mitochondrial antigens and following autoimmune pathogenesis in primary biliary cirrhosis (PBC). We examined an involvement of endoplasmic reticulum (ER) stress in the deregulated autophagy and cellular senescence in PBC.

METHODS

We examined the degree of ER stress using markers; glucose-regulated protein 78 (GRP78) and protein disulfide isomerases (PDI), autophagy and cellular senescence in cultured BECs treated with an ER stress inducer, tunicamycin (TM), glycochenodeoxycholic acid (GCDC), and palmitic acid (PA), and the effect of pretreatment with tauroursodeoxycholic acid (TUDCA). We examined the expression of PDI and GRP78 in livers taken from the patients with PBC (n = 43) and 75 control livers.

RESULTS

The expression of ER stress markers was significantly increased in cultured BECs treated with TM, GCDC or PA in BECs (p < 0.05), and pretreatment with TUDCA significantly suppressed the induced ER stress (p < 0.05). Autophagy, deregulated autophagy, and cellular senescence were induced in BECs treated with TM, GCDC, or PA. Pretreatment with TUDCA further increased autophagy in BECs treated with PA and suppressed cellular senescence caused by treatments with TM, GCDC, or PA (p < 0.05). A granular expression of PDI and GRP78 was significantly more extensive in small bile ducts in PBC, compared with control livers (p < 0.05). The expression of GRP78 was seen in senescent BECs in PBC.

CONCLUSIONS

ER stress may play a role in the pathogenesis of deregulated autophagy and cellular senescence in biliary epithelial lesions in PBC.

Role of autophagy in the pathogenesis of multiple sclerosis

Autophagy plays an important role in maintaining the cellular homeostasis. One of its functions is to degrade unnecessary organelles and proteins for energy recycling or amino-acids for cell survival. Ablation of autophagy leads to neurodegeneration. Multiple sclerosis (MS), a permanent neurological impairment typical of chronic inflammatory demyelinating disorder, is an auto-immune disease of the central nervous system (CNS). Autophagy is tightly linked to the innate and adaptive immune systems during the autoimmune process, and several studies have shown that autophagy directly participates in the progress of MS or experimental autoimmune encephalomyelitis (EAE, a mouse model of MS). Dysfunction of mitochondria that intensively influences the autophagy pathway is one of the important factors in the pathogenesis of MS. Autophagy-related gene (ATG) 5 and immune-related GTPase M (IRGM) 1 are increased, while ATG16L2 is decreased, in T-cells in EAE and active relapsing-remitting MS brains. Administration of rapamycin, an inhibitor of mammalian target of rapamycin ( mTOR), ameliorates relapsing-remitting EAE. Inflammation and oxidative stress are increased in MS lesions and EAE, but Lamp2 and the LC3-II/LC3-I ratio are decreased. Furthermore, autophagy in various glial cells plays important roles in regulating neuro-inflammation in the CNS, implying potential roles in MS. In this review, we discuss the role of autophagy in the peripheral immune system and the CNS in neuroinflammation associated with the pathogenesis of MS.