Autophagy and inflammation

Loss of stearoyl-CoA desaturase 2 disrupts inflammatory response in macrophages

Macrophages are innate immune cells that patrol tissues and are the first responders to detect infection. They orchestrate the host immune response in eliminating invading pathogens and the subsequent transition from inflammation to tissue repair. Macrophage dysfunction contributes to age-related pathologies, including low-grade inflammation in advanced age that is termed "inflammaging." Our laboratory has previously identified that macrophage expression of a fatty acid desaturase, stearoyl-CoA desaturase 2 (SCD2), declines with age. Herein, we delineate the precise cellular effects of SCD2 deficiency in murine macrophages. We found that deletion of Scd2 from macrophages dysregulated basal and bacterial lipopolysaccharide (LPS)-stimulated transcription of numerous inflammation-associated genes. Specifically, deletion of Scd2 from macrophages decreased basal and LPS-induced expression of Il1b transcript that corresponded to decreased production of precursor IL1B protein and release of mature IL1B. Furthermore, we identified disruptions in autophagy and depletion of unsaturated cardiolipins in SCD2-deficient macrophages. To assess the functional relevance of SCD2 in the macrophage response to infection, we challenged SCD2-deficient macrophages with uropathogenic Escherichia coli and found that there was impaired clearance of intracellular bacteria. This increased burden of intracellular bacteria was accompanied by increased release of pro-inflammatory cytokines IL6 and TNF but decreased IL1B. Taken together, these results indicate that macrophage expression of Scd2 is necessary for maintaining the macrophage response to inflammatory stimuli. This link between fatty acid metabolism and fundamental macrophage effector functions may potentially be relevant to diverse age-related pathologies. IMPORTANCE Macrophages are immune cells that respond to infection, but their dysfunction is implicated in many age-related diseases. Recent evidence showed that macrophage expression of a fatty acid enzyme, stearoyl-CoA desaturase 2, declines in aged organisms. In this work, we characterize the effects when stearoyl-CoA desaturase 2 is deficient in macrophages. We identify aspects of the macrophage inflammatory response to infection that may be affected when expression of a key fatty acid enzyme is decreased, and these findings may provide cellular insight into how macrophages contribute to age-related diseases.

Potential benefits of medium chain fatty acids in aging and neurodegenerative disease

Neurodegenerative diseases are a large class of neurological disorders characterized by progressive dysfunction and death of neurones. Examples include Alzheimer's disease, Parkinson's disease, frontotemporal dementia, and amyotrophic lateral sclerosis. Aging is the primary risk factor for neurodegeneration; individuals over 65 are more likely to suffer from a neurodegenerative disease, with prevalence increasing with age. As the population ages, the social and economic burden caused by these diseases will increase. Therefore, new therapies that address both aging and neurodegeneration are imperative. Ketogenic diets (KDs) are low carbohydrate, high-fat diets developed initially as an alternative treatment for epilepsy. The classic ketogenic diet provides energy via long-chain fatty acids (LCFAs); naturally occurring medium chain fatty acids (MCFAs), on the other hand, are the main components of the medium-chain triglyceride (MCT) ketogenic diet. MCT-based diets are more efficient at generating the ketone bodies that are used as a secondary energy source for neurones and astrocytes. However, ketone levels alone do not closely correlate with improved clinical symptoms. Recent findings suggest an alternative mode of action for the MCFAs, e.g., via improving mitochondrial biogenesis and glutamate receptor inhibition. MCFAs have been linked to the treatment of both aging and neurodegenerative disease via their effects on metabolism. Through action on multiple disease-related pathways, MCFAs are emerging as compounds with notable potential to promote healthy aging and ameliorate neurodegeneration. MCFAs have been shown to stimulate autophagy and restore mitochondrial function, which are found to be disrupted in aging and neurodegeneration. This review aims to provide insight into the metabolic benefits of MCFAs in neurodegenerative disease and healthy aging. We will discuss the use of MCFAs to combat dysregulation of autophagy and mitochondrial function in the context of "normal" aging, Parkinson's disease, amyotrophic lateral sclerosis and Alzheimer's disease.

Melatonin: a promising neuroprotective agent for cerebral ischemia-reperfusion injury

Cerebral ischemia-reperfusion (CIR) injury is initiated by the generation of reactive oxygen species (ROS), which leads to the oxidation of cellular proteins, DNA, and lipids as an initial event. The reperfusion process impairs critical cascades that support cell survival, including mitochondrial biogenesis and antioxidant enzyme activity. Failure to activate prosurvival signals may result in increased neuronal cell death and exacerbation of CIR damage. Melatonin, a hormone produced naturally in the body, has high concentrations in both the cerebrospinal fluid and the brain. However, melatonin production declines significantly with age, which may contribute to the development of age-related neurological disorders due to reduced levels. By activating various signaling pathways, melatonin can affect multiple aspects of human health due to its diverse range of activities. Therefore, understanding the underlying intracellular and molecular mechanisms is crucial before investigating the neuroprotective effects of melatonin in cerebral ischemia-reperfusion injury.

Paeoniflorin, ferulic acid, and atractylenolide III improved LPS-induced neuroinflammation of BV2 microglia cells by enhancing autophagy

Microglia hyperactivation is an important cause of neuroinflammation in Alzheimer's disease (AD). Paeoniflorin (PF), ferulic acid (FA), and atractylenolide III (ATL) are potent in anti-inflammation and neuroprotection. Multiple components can act on different targets simultaneously to exert synergistic therapeutic effects and exploring the synergistic potential between compounds is an important area of research. We investigated the effects of PF, FA, and ATL, alone or in combination, on LPS-induced neuroinflammation and autophagy in BV2 microglia cells. We found that PF, FA, and ATL, alone or in combination, significantly reduced the production of inflammatory factors such as IL-6, IL-1β, and TNF-α, especially in the PF + FA + ATL group, which performed the best. In addition, the combination of PF, FA, and ATL significantly increased the expression of autophagy-related proteins p-AMPK, p-ULK1, Beclin1, LC3, and TFEB and decreased the expression of p62. Moreover, the restoration of autophagic flux by the combination of PF, FA, and ATL was abrogated by the addition of the autophagy inhibitor Wortmannin. In conclusion, PF, FA, and ATL have a synergistic effect in reducing LPS-induced inflammatory factor release from BV2 microglia cells, and its protective effect may be through activation of the AMPK/ULK1/TFEB autophagic signaling pathway.

Autophagy-related genes analysis reveals potential biomarkers for prediction of the impaired walking capacity of peripheral arterial disease

BACKGROUND

The role of autophagy and autophagy-related genes in peripheral arterial disease (PAD) remains unknown and may be of diagnostic and prognostic value. The aim of this study is to investigate the relationship between autophagy and PAD, and identify potential diagnostic or prognostic biomarkers for medical practice.

METHODS

Differentially expressed autophagy-related genes in PAD were explored from GSE57691 and validated in our WalkByLab registry participants by quantitative real-time polymerase chain reaction (qRT-PCR). The level of autophagy in peripheral blood mononuclear cells (PBMCs) of WalkByLab participants was assessed by analyzing autophagic marker proteins (beclin-1, P62, LC3B). Single sample gene set enrichment analysis (ssGSEA) was used to evaluate the immune microenvironment within the artery wall of PAD patients and healthy persons. Chemokine antibody array and enzyme-linked immunosorbent assay were used to assess the chemokines in participants' plasma. Treadmill testing with Gardner protocol was used to evaluate participants' walking capacity. Pain-free walking distance, maximum walking distance, and walking time were recorded. Finally, a nomogram model based on logistic regression was built to predict impaired walking performance.

RESULTS

A total of 20 relevant autophagy-related genes were identified, and these genes were confirmed to be expressed at low levels in our PAD participants. Western blotting demonstrated that the expression of autophagic marker proteins beclin-1 and LC3BII were significantly reduced in PAD patients' PBMCs. ssGSEA revealed that most of the autophagy-related genes were strongly correlated with immune function, with the largest number of associated genes showing interaction between cytokine-and-cytokine receptors (CCR). In this context, the chemokines growth-related oncogene (GRO) and neutrophil activating protein2 (NAP2) are highly expressed in the plasma of WalkByLab PAD patients and were significantly negatively correlated with the walking distance assessed by Gardner treadmill testing. Finally, the plasma NAP2 level (AUC: 0.743) and derived nomogram model (AUC: 0.860) has a strong predictive potential to identify a poor walking capacity.

CONCLUSIONS

Overall, these data highlight both the important role of autophagy and autophagy-related genes in PAD and link them to vascular inflammation (expression of chemokines). In particular, chemokine NAP2 emerged as a novel biomarker that can be used to predict the impaired walking capacity in PAD patients.

Sporothrix globosa melanin regulates autophagy via the TLR2 signaling pathway in THP-1 macrophages

Melanin, an important virulence factor of pathogenic fungi, has been shown to suppress host immune responses in multiple ways. Autophagy is a vital cellular mechanism underlying the host's innate immunity against microbial infections. However, the potential influence of melanin on autophagy has not been explored. We investigated the effect of melanin on autophagy in macrophages, which play a key role in controlling Sporothrix spp. infection, as well as the mechanism of melanin interaction with Toll-like receptor (TLR)-induced pathways. Sporothrix globosa conidia (wild-type and melanin-deficient mutant strains) or yeast cells were co-cultured with THP-1 macrophages to demonstrate that, although S. globosa infection led to the activation of autophagy-related proteins and increased autophagic flux, S. globosa melanin suppressed macrophage autophagy. Incubation with S. globosa conidia also increased the expression levels of reactive oxygen species and multiple proinflammatory cytokines (interleukin-6, tumor necrosis factor-α, interleukin-1β and interferon-γ) in macrophages. These effects were attenuated as melanin presented. Furthermore, while S. globosa conidia significantly increased the expression of both TLR2 and TLR4 in macrophages, the knockdown of TLR2, but not TLR4, with small interfering RNA suppressed autophagy. Overall, this study revealed the novel immune defense ability of S. globosa melanin to inhibit macrophage functionality by resisting macrophage autophagy through the regulation of TLR2 expression.

CDK5RAP3, a key defender of udder, modulates NLRP3 inflammasome activation by regulating autophagolysosome degradation in S. agalactiae-infected mastitis

Streptococcus agalactiae, as one of the main pathogens of clinical and subclinical mastitis, affects animal welfare and leads to huge economic losses to farms due to the sharp decline in milk yield. However, both the real pathogenic mechanisms of S. agalactiae-induced mastitis and the regulator which controls the inflammation and autophagy are largely unknown. Served as a substrate of ubiquitin-like proteins of E3 ligase, CDK5RAP3 is widely involved in the regulation of multiple signaling pathways. Our findings revealed that CDK5RAP3 was significantly down-regulated in mastitis infected by S. agalactiae. Surprisingly, inflammasome activation was triggered by CDK5RAP3 knockdown: up-regulated NLRP3, IL1β and IL6, and cleaved caspase1 promoting by NF-κB, thereby resulting in pyroptosis. Additionally, the accumulation of autophagy markers (LC3B and p62) after CDK5RAP3 knockdown suggested that the autophagolysosome degradation pathway was inhibited, thereby activating the NF-κB pathway and NLRP3 inflammasome. Hence, our findings suggest that downregulation or ablation of CDK5RAP3 inhibits autophagolysosome degradation, causes inflammation by activating the NF-κB /NLRP3 inflammasome, and triggers cell death. In conclusion, CDK5RAP3 holds the key to understanding the interaction between autophagy and immune responses, its anti-inflammatory role in this study will throw new light on the clinical drug discovery to cure S. agalactiae mastitis.

Effects of Prunus Tomentosa Thumb Total Flavones on adjuvant arthritis in rats and regulation of autophagy

BACKGROUND

Rheumatoid arthritis (RA) is a slow in taking effect systemic autoimmune disease. Prunus Tomentosa Thumb Total Flavones (PTTTF) has anti-inflammatory and antioxidant properties.

OBJECTIVE

The purpose of this study is to the PTTTF on adjuvant arthritis (AA) in rats and to explore the mechanism of autophagy.

METHODS

Adjuvant arthritis model was established in rats. The cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-17 (IL-17), tumor necrosis factor (TNF-α) of rat synovial tissue were determined by RT-PCR. The histopathological varieties of knee joints in AA rats were observed by HE staining. The expressions of autophagy-related proteins ATG5, ATG7, ATG12, Beclin1, Lc3II and Bcl-2 in rat synovial tissue were determined by Western Blotting.

RESULTS

PTTTF (50, 100, 200 mg/kg) significantly inhibited inflammation in rats (P< 0.01). PTTTF significantly inhibited inflammatory factor COX in rat synovial tissue. COX-2, IL-1β, IL-6, IL-17, TNF-α expression (P< 0.05); PTTTF can significantly improve the pathological damage of rat knee joint PTTTF and can significantly inhibited the expression of autophagy-related proteins in rat synovium (P< 0.05 ).

CONCLUSION

PTTTF can inhibit adjuvant arthritis in rats and can inhibit the expression of autophagy-related proteins ATG5, ATG7, ATG12, Beclin1, Lc3II and Bcl-2.

Cellular Prion Protein Attenuates OGD/R-Induced Damage by Skewing Microglia toward an Anti-inflammatory State via Enhanced and Prolonged Activation of Autophagy

Modulation of microglial pro/anti-inflammatory states and autophagy are promising new therapies for ischemic stroke, but the underlying mechanisms remain largely unexplored. The objective of the study is to determine the intrinsic role of PrP^C (cellular prion protein) in the regulation of microglial inflammatory states and autophagy in ischemic stroke. PrP^C was expressed in murine microglia, and an in vitro oxygen-glucose deprivation/reperfusion (OGD/R) model was established in microglia of different PRNP genotypes. During reperfusion following OGD, wild-type (WT) microglia had significantly increased pro/anti-inflammatory microglial percentages and related cytokine [interleukin [IL]-6, IL-10, IL-4, tumor necrosis factor, and interferon-gamma] release at reperfusion after 48 or 72 h. WT microglia also showed greater accumulation of the autophagy markers LC3B-II/I (microtubule-associated protein B-light chain 3), but not of p62 or LAMP1 (lysosome-associated membrane protein) at reperfusion after 24 h and 48 h. Inhibition of autophagy using 3-methyladenine or bafilomycin A1 aggravated the OGD/R-induced pro-inflammatory state, and the effect of 3-methyladenine was significantly stronger than that of bafilomycin A1. Concomitantly, PRNP knockout shortened the accumulation of LC3B-II/I, suppressed microglial anti-inflammatory states, and further aggravated the pro-inflammatory states. Conversely, PRNP overexpression had the opposite effects. Bafilomycin A1 reversed the effect of PrP^C on microglial inflammatory state transformation. Moreover, microglia with PRNP overexpression exhibited higher levels of LAMP1 expression in the control and OGD/R groups and delayed the OGD/R-induced decrease of LAMP1 to reperfusion after 48 h. PrP^C attenuates OGD/R-induced damage by skewing microglia toward an anti-inflammatory state via enhanced and prolonged activation of autophagy.

Neuroprotective effect of Vesatolimod in an experimental autoimmune encephalomyelitis mice model

BACKGROUND

Multiple sclerosis is a chronic demyelinating autoimmune disease accompanied by inflammation and loss of axons and neurons. Toll-like receptors play crucial roles in the innate immune system and inflammation. However, few studies have explored the specific effects of toll-like receptor 7 signaling pathway in multiple sclerosis. To explore underlying effects to develop a new therapeutic target, we use Vesatolimod, a safe and well-tolerated agonist of toll-like receptor 7, to assess the possible effects in Experimental autoimmune encephalomyelitis (EAE) animal model.

METHODS

EAE animal model was induced by injection of MOG35-55 and monitored daily for clinical symptoms, and the treatment group was given Vesatolimod at the onset of illness. The therapeutic effects of Vesatolimod on EAE inflammation, demyelination, CD107b cells and T cells infiltration, and microglia activation was evaluated. Autophagy within the spinal cords of EAE mice was also preliminarily assessed.

RESULTS

Treatment with Vesatolimod significantly alleviated clinical symptoms of EAE from day 18 post-immunization and decreased the expression levels of inflammatory cytokines, particularly Eotaxin and IL-12 (P40), in peripheral blood. It also inhibited demyelination in spinal cords. Moreover, VES treatment reduced activation of microglia, infiltration of CD3 + T cells and CD107b + cells, as well as inhibited the autophagy-related proteins expression in the spinal cords of EAE mice.

CONCLUSION

Our results indicate that Vesatolimod exhibits protective effects on EAE mice and is promising for treatment of MS.

Selenium ameliorates inflammation by decreasing autophagic flux and mitogen-activated protein kinase signalling on experimentally induced rat periapical lesions

AIM

To reveal the molecular mechanisms that targets mitogen-activated protein kinase (MAPK) signalling and the autophagic flux and to investigate the possible effects of the systemic administration of selenium (Se) on experimentally induced rat periapical lesions.

METHODOLOGY

Thirty adult Sprague-Dawley rats were divided equally into negative control, positive control and Se groups. In the positive control and Se groups, the pulp chambers of their mandibular first molars were exposed to the oral environment to induce periapical lesions The Se group received daily intraperitoneal injections of Se at a dose of 0.1 mg kg^-1 . After 28 days, the amount of bone destruction; severity of inflammation; penetration of microorganisms along the root canal; collagen degradation in periodontal ligament; interleukin (IL)-6, hypoxia-inducible factor-1 (HIF-1), cyclooxygenase-2 (COX-2) and caspase-3 expression; autophagic flux; and p38 MAPK signalling were evaluated using radiographic, histopathological, Gram staining, picrosirius red stain, immunohistochemical, quantitative real-time polymerase chain (qRT-PCR) and Western blot methods, respectively. These data were analysed through the Kruskal-Wallis and Dunnett's tests (p < .05).

RESULTS

The area of radiographic periapical bone loss, histopathological scores, the area of periapical bone loss and the scores for the bacteria localisation, the intensity of immunohistochemical staining for IL-6, HIF-1, COX-2 and caspase-3 in the Se group was significantly less than those of the positive control group (p < .01). The mRNA expression levels of Beclin-1, Atg3, Atg5, Atg7 and Atg16L1 were lower in the Se group than in the positive control group (p < .01). The protein expressions of Beclin-1, Atg5 and LC3-II, the phosphorylation ratio of the p38 MAPK and the ratios of LC3II/LC3I were significantly higher (p < .05) in the positive control and Se groups. On the contrary, the expression of the p62/SQSTM1 protein was significantly lower (p < .05) in the positive control and Se groups than in the negative control group.

CONCLUSION

The induction of periapical lesions in rats increased autophagic flux and activated p38 MAPK signal transduction processes. Se suppressed the inflammatory process, reduced bone destruction and both the autophagic flux and p38 MAPK activation.

Inflammasome activation by Gram-positive bacteria: Mechanisms of activation and regulation

The inflammasomes are intracellular multimeric protein complexes consisting of an innate immune sensor, the adapter protein ASC and the inflammatory caspases-1 and/or -11 and are important for the host defense against pathogens. Activaton of the receptor leads to formation of the inflammasomes and subsequent processing and activation of caspase-1 that cleaves the proinflammatory cytokines IL-1β and IL-18. Active caspase-1, and in some instances caspase-11, cleaves gasdermin D that translocates to the cell membrane where it forms pores resulting in the cell death program called pyroptosis. Inflammasomes can detect a range of microbial ligands through direct interaction or indirectly through diverse cellular processes including changes in ion fluxes, production of reactive oxygen species and disruption of various host cell functions. In this review, we will focus on the NLRP3, NLRP6, NLRC4 and AIM2 inflammasomes and how they are activated and regulated during infections with Gram-positive bacteria, including Staphylococcus spp., Streptococcus spp. and Listeria monocytogenes.

Platelet-rich Plasma (PRP) in the Treatment of Diabetic Foot Ulcers and its Regulation of Autophagy

Objective: Through clinical trials, this study observes the therapeutic effect of platelet-rich plasma (platelet-rich plasma, PRP) on diabetic foot ulcers and explored the relationship between the relationship between PRP and autophagy. Methods: Thirty patients with diabetic foot ulcer who met the relevant criteria were randomly divided into PRP treatment group and control group. In the PRP treatment group, the formed PRP gel was coated and bandaged on the diabetic foot ulcer wound, and the PRP treatment was repeated on the seventh day. The control group was covered with normal saline sterile gauze. Observe the healing rate of the wound in 7 days, 14 days and 21 days, the pain in 5 consecutive days and the healing time of the wound after treatment, collect wound granulation tissues before and twenty-first days after treatment then detect the expression of autophagy-related proteins (LC-3, P62) and inflammatory factors (IL-6, IL-10) in diabetic foot ulcer wound to investigate the potential relationship between PRP treatment of diabetic foot ulcers and autophagy and inflammatory responses. Results: The wound healing rate of diabetic foot ulcer patients in the PRP treatment group was higher than that in the control group on the seventh, 14th and 21st days, the healing time (31.40 ± 4.47) was better than that in the control group (43.20 ± 5.03) days, and the pain improvement was better than that in the control group (P < .05). The results of Western blot analysis and quantitative PCR of autophagy-related proteins (LC-3 and p62) in granulation tissue showed that the values of LC3 and LC3-II/LC3-I and the expression of LC3 gene in wound granulation tissue of PRP group were significantly higher than those before treatment (P < .05). The value and gene expression of P62 protein were lower than those before treatment (P < .05). In the control group, there was no significant difference in LC3 and P62 protein gray level and gene expression before and after treatment (P > .05). The level of autophagy in the wound of PRP group increased after treatment, while there was no statistical significance in the control group. The results of ELISA showed that the concentration of IL-6 in granulation tissue of the PRP treatment group was lower than that before treatment (P < .05), while there was no significant difference in IL-6 in the control group after treatment. The concentration of IL-10 increased in both groups after treatment, but the concentration in PRP group was higher than that in control group (P < .05). Conclusions: This study shows that PRP gel has advantages in accelerating wound healing, relieving pain, shortening healing time and reducing inflammatory response in treating diabetic foot ulcers wound, which may be related to autophagy, and provides new ideas for the treatment of diabetic foot ulcers.

Perturbed autophagy intervenes systemic lupus erythematosus by active ingredients of traditional Chinese medicine

Systemic lupus erythematosus (SLE) is a common multisystem, multiorgan heterozygous autoimmune disease. The main pathological features of the disease are autoantibody production and immune complex deposition. Autophagy is an important mechanism to maintain cell homeostasis. Autophagy functional abnormalities lead to the accumulation of apoptosis and induce the autoantibodies that result in immune disorders. Therefore, improving autophagy may alleviate the development of SLE. For SLE, glucocorticoids or immunosuppressive agents are commonly used in clinical treatment, but long-term use of these drugs causes serious side effects in humans. Immunosuppressive agents are expensive. Traditional Chinese medicines (TCMs) are widely used for immune diseases due to their low toxicity and few side effects. Many recent studies found that TCM and its active ingredients affected the pathological development of SLE by regulating autophagy. This article explains how autophagy interferes with immune system homeostasis and participates in the occurrence and development of SLE. It also summarizes several studies on TCM-regulated autophagy intervention in SLE to generate new ideas for basic research, the development of novel medications, and the clinical treatment of SLE.

Sustained systemic inflammation increases autophagy and induces EMT/fibrotic changes in mouse liver cells: Protection by melatonin

The unending lifestyle stressors along with genetic predisposition, environmental factors and infections have pushed the immune system into a state of constant activity, leading to unresolved inflammation and increased vulnerability to chronic diseases. Liver fibrosis, an early-stage liver condition that increases the risk of developing liver diseases like cirrhosis and hepatocellular carcinoma, is among the various diseases linked to inflammation that dominate worldwide morbidity and mortality. We developed a mouse model with low-grade lipopolysaccharide (LPS) exposure that shows hepatic damage and a pro-inflammatory condition in the liver. We show that inflammation and oxidative changes increase autophagy in liver cells, a degradation process critical in maintaining cellular homeostasis. Our findings from in vivo and in vitro studies also show that induction of both inflammation and autophagy trigger epithelial-mesenchymal transition (EMT) and pro-fibrotic changes in hepatocytes. Inhibiting the inflammatory pathways with a naturally occurring NF-κB inhibitor and antioxidant, melatonin, could assuage the changes in autophagy and activation of EMT/fibrotic pathways in hepatocytes. Taken together, this study shows a pathway linking inflammation and autophagy which could be targeted for future drug development to delay the progression of liver fibrosis.

Role of autophagy in aging: The good, the bad, and the ugly

Autophagy (self-eating) is a conserved catabolic homeostatic process required for cellular metabolic demands by removal of the damaged molecules and organelles and for alleviation of stress initiated by pathology and infection. By such actions, autophagy is essential for the prevention of aging, disease, and cancer. Genetic defects of autophagy genes lead to a host of developmental, metabolic, and pathological aberrations. Similarly, the age-induced decline in autophagy leads to the loss of cellular homeostatic control. Paradoxically, such a valuable mechanism is hijacked by diseases, during tumor progression and by senescence, presumably due to high levels of metabolic demand. Here, we review both the role of autophagy in preventing cellular decline in aging by fulfillment of cellular bioenergetic demands and its contribution to the maintenance of the senescent state and SASP by acting on energy and nutritional sensors and diverse signaling pathways.

Dexmedetomidine attenuates subarachnoid hemorrhage-induced acute lung injury through regulating autophagy and TLR/NFκB signaling pathway

BACKGROUND

Acute lung injury (ALI) is the most serious complication of subarachnoid hemorrhage (SAH). We investigated role of autophagy and inflammatory signaling pathways in lung damage and therapeutic effects of dexmedetomidine (DEX).

METHODS

Fifty male Wistar rats were randomly divided into five groups: sham, SAH, SAH+ DEX5, SAH+DEX25, and SAH+DEX50. SAH was induced using endovascular perforation technique. All rats received mechanical ventilation for 60 minutes. At 2 and 24 h of SAH induction, SAH+DEX groups were treated with 5, 25, and 50 µg/kg of DEX, respectively. Histological ALI score and pulmonary edema were assessed after 48 h. Lung expression of LC3B, ATG3, p62, TLR4, TLR9, and NFκB was assessed using western blotting and quantitative PCR. Blood levels of IL-6, IL-1β, IFN-γ, and TNFα were also assessed.

RESULTS

SAH induced ALI and pulmonary edema, which were attenuated in SAH+DEX5 (P < 0.001 for both) and SAH+DEX25 groups (P = 0.001 and P < 0.001 for ALI and edema, respectively). Lung expressions of LC3B and ATG3 were upregulated in SAH group, which was attenuated in SAH+DEX5 and SAH+DEX25 groups. Lung expressions of TLR4, TLR9, and NFκB were increased in SAH group, which was attenuated in SAH+DEX5 group. Blood IL-6 level was increased in SAH group and attenuated in SAH+DEX5 and SAH+DEX25 groups. Blood IFN-γ level was lower in SAH group than in sham group, and it was increased in SAH+DEX25 group.

CONCLUSIONS

Low-dose DEX treatment after SAH may protect against ALI by disrupting pathological brain-lung crosstalk and alleviating autophagy flux and TLR-dependent inflammatory pathways.

Catechol-chitosan/polyacrylamide hydrogel wound dressing for regulating local inflammation

Chronic wounds and the accompanying inflammation are ongoing challenges in clinical treatment. They are usually accompanied by low pH and high oxidative stress environments, limiting cell growth and proliferation. Ordinary medical gauze has limited therapeutic effects on chronic wounds, and there is active research to develop new wound dressings. The chitosan hydrogel could be widely used in biomedical science with great biocompatibility, but the low mechanical properties limit its development. This work uses polyacrylamide to prepare double-network (DN) hydrogels based on bioadhesive catechol-chitosan hydrogels. Cystamine and N, N′-Bis(acryloyl)cystamine, which can be cross-linking agents with disulfide bonds to prepare redox-responsive DN hydrogels and pH-responsive nanoparticles (NPs) prepared by acetalized cyclodextrin (ACD) are used to intelligently release drugs against chronic inflammation microenvironments. The addition of catechol groups and ACD-NPs loaded with the Resolvin E1 (RvE1), promotes cell adhesion and regulates the inflammatory response at the wound site. The preparation of the DN hydrogel in this study can be used to treat and regulate the inflammatory microenvironment of chronic wounds accurately. It provides new ideas for using inflammation resolving factor loaded in DN hydrogel of good biocompatibility with enhanced mechanical properties to intelligent regulate the wound inflammation and promote the wound repaired.

•

Dual-response hydrogel drug delivery system was used to intelligently release drugs at inflammation area of chronic wound.

•

DN hydrogel was designed to enhance the properties of chitosan-based hydrogel with two cross-linking agents.

•

Resolvin E1 loaded into wound dressing can help to regulate wound inflammation by regulating macrophage behavior.

Exosomes-based therapy of stroke, an emerging approach toward recovery

Based on clinical observations, stroke is touted as one of the specific pathological conditions, affecting an individual’s life worldwide. So far, no effective treatment has been introduced to deal with stroke post-complications. Production and release of several neurotrophic factors by different cells exert positive effects on ischemic areas following stroke. As a correlate, basic and clinical studies have focused on the development and discovery of de novo modalities to introduce these factors timely and in appropriate doses into the affected areas. Exosomes (Exo) are non-sized vesicles released from many cells during pathological and physiological conditions and participate in intercellular communication. These particles transfer several arrays of signaling molecules, like several neurotrophic factors into the acceptor cells and induce specific signaling cascades in the favor of cell bioactivity. This review aimed to highlight the emerging role of exosomes as a therapeutic approach in the regeneration of ischemic areas.

The emerging role of autophagy and mitophagy in tauopathies: From pathogenesis to translational implications in Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease, affecting more than 55 million individuals worldwide in 2021. In addition to the "amyloid hypothesis," an increasing number of studies have demonstrated that phosphorylated tau plays an important role in AD pathogenesis. Both soluble tau oligomers and insoluble tau aggregates in the brain can induce structural and functional neuronal damage through multiple pathways, eventually leading to memory deficits and neurodegeneration. Autophagy is an important cellular response to various stress stimuli and can generally be categorized into non-selective and selective autophagy. Recent studies have indicated that both types of autophagy are involved in AD pathology. Among the several subtypes of selective autophagy, mitophagy, which mediates the selective removal of mitochondria, has attracted increasing attention because dysfunctional mitochondria have been suggested to contribute to tauopathies. In this review, we summarize the latest findings on the bidirectional association between abnormal tau proteins and defective autophagy, as well as mitophagy, which might constitute a vicious cycle in the induction of neurodegeneration. Neuroinflammation, another important feature in the pathogenesis and progression of AD, has been shown to crosstalk with autophagy and mitophagy. Additionally, we comprehensively discuss the relationship between neuroinflammation, autophagy, and mitophagy. By elucidating the underlying molecular mechanisms governing these pathologies, we highlight novel therapeutic strategies targeting autophagy, mitophagy and neuroinflammation, such as those using rapamycin, urolithin, spermidine, curcumin, nicotinamide, and actinonin, for the prevention and treatment of AD.

Effect of calorie-restriction and rapamycin on autophagy and the severity of caerulein-induced experimental acute pancreatitis in mice

Background

Impaired autophagy contributes to development of acute pancreatitis (AP). We studied the effect of inducing autophagy by calorie-restriction and rapamycin, separately, in the caerulein-induced model of severe AP.

Methods

Adult, male, Swiss albino mice were given eight, hourly, intraperitoneal injections of caerulein (Ce) (50µg/Kg/dose). The interventions were calorie restriction (CR) and rapamycin (2mg/Kg). Mice were sacrificed at the 9th hour. Pancreas was harvested for histopathology and immunoblotting. Amylase activity and the levels of cytokines were measured in plasma.

Results

The histopathological score and amylase activity were significantly lower in calorie-restricted caerulein-induced AP (CRCeAP) in comparison to animals that had unrestricted access to chow. In the CRCeAP group, levels of IL-6 and GM-CSF in plasma were lower and the expression of LC3II and Beclin-1 were higher. On transmission electron-microscopy, the area occupied by autophagic vacuoles was higher in CRCeAP. The expression of caspase-8 and caspase-9 was also higher in CRCeAP. In rapamycin with caerulein-induced AP (Rapa+CeAP), the histopathological score and amylase activity were significantly lower than caerulein-induced AP (CeAP). In Rapa+CeAP, the expression of LC3II and Beclin-1 were higher, whereas; SQSTM1 was decreased. The number of autophagic vacuoles in Rapa+CeAP group was fewer. Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) were lower in Rapa+CeAP. Caspase-3 increased and high mobility group box 1 (HMGB1) decreased in Rapa+CeAP.

Conclusion

Calorie-restriction and rapamycin can individually decrease the severity of injury in the caerulein-induced model of severe AP.

Antrodia Camphorata Polysaccharide activates autophagy and regulates NLRP3 degradation to improve liver injury-related inflammatory response

This study illustrated the liver protection mechanism of ACP from the perspective of autophagy activation. ACP suppressed the inflammatory injury of KCs, and decreased the cell apoptosis rate. After LTG and LC3 staining, ACP promoted lysosomal production, increased LC3 expression, activated autophagy, and suppressed the expression of NLRP3 and inflammatory factors. Under the electron microscope, ACP accelerated the production of autophagosomes. After simultaneous treatment with 3-MA and ACP, the effect of ACP on resisting KC injury decreased, the expression of NLRP3 was up-regulated, and autophagy was suppressed. As discovered in the mouse model of liver injury, ACP inhibited the ALT and AST levels, promoted the occurrence of autophagy, reduced NLRP3 expression and alleviated liver injury. ACP activates autophagy to induce NLRP3 degradation, thus suppressing inflammatory response in liver injury and exerting the liver protection effect, which is one of the mechanisms of action of ACP.

Evogliptin Directly Inhibits Inflammatory and Fibrotic Signaling in Isolated Liver Cells

Chronic liver inflammation can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. Kupffer cells (KC) secrete proinflammatory and fibrogenic cytokines in response to lipopolysaccharide (LPS), and so play an important role in liver inflammation, where they induce hepatocellular damage. LPS also activates hepatic stellate cells and induces extracellular matrix deposition. In this study, we used isolated primary KC, primary hepatocytes, and primary hepatic stellate cells (HSC) to investigate whether evogliptin directly inhibits inflammatory and fibrotic signaling. We found that evogliptin inhibited LPS-induced secretion of inducible nitric oxide synthase and transforming growth factor β (TGF-β) from KC. Moreover, evogliptin inhibited inflammatory mediator release from hepatocytes and hepatic stellate cell activation that were induced by KC-secreted cytokines. In hepatocytes, evogliptin also inhibited LPS-induced expression of proinflammatory cytokines and fibrotic TGF-β. In addition, evogliptin inhibited TGF-β-induced increases in connective tissue growth factor levels and HSC activation. These findings indicate that evogliptin inhibits inflammatory and fibrotic signaling in liver cells. We also showed that the inhibitory effect of evogliptin on inflammatory and fibrotic signaling is associated with the induction of autophagy.

Transcriptome analysis identifies IL24 as an autophagy modulator in PM2.5 caused lung dysfunction

BACKGROUND

Evidence suggests that exposure to PM_2.5 increased hospitalization and mortality rates of respiratory diseases. However, the potential biomarkers and targets associated with PM_2.5-induced lung dysfunction are not fully discovered.

METHODS

Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and HALLMARK enrichment analysis of the RNA-seq data (Beas-2B cells treated with PM_2.5) were applied. Gene set enrichment analysis (GSEA) was performed to identify the biological processes correlated with autophagy. Three gene expression profile datasets (GSE158954, GSE155616 and GSE182199) were downloaded from the Gene Expression Omnibus (GEO) database to identify the potential targets. PM_2.5-exposed mice were constructed. Real-time qPCR, siRNA transfection, western blot, immunofluorescence, and pathological staining were applied for validation both in vitro and in vivo studies.

RESULTS

GO, KEGG and HALLMARK enrichment based on RNA-seq data showed that the differentially expressed genes (DEGs) were associated with autophagy like lysosome and macroautophagy. GSEA analysis revealed that PM_2.5 was positively correlated with autophagy-related biological processes compared with control group. Venn diagrams identified IL24 was upregulated in our data as well as in these three datasets (GSE158954, GSE155616 and GSE182199) after PM_2.5 exposure. Consistent with the analysis, activation of autophagy by PM_2.5 was validated in vivo and in vitro. In PM_2.5-exposed mice, lung pathological changes were observed, including airway inflammation and mucus secretion. The mRNA and protein levels of the key gene, IL24, were significantly increased. Moreover, Bafilomycin A1, the inhibitor of autophagy, inhibited the autophagy and ameliorated lung injury induced by PM2.5. Furthermore, downregulation of IL24 decreased autophagy activity. Meanwhile, IL24 was regulated by mTOR signaling.

CONCLUSIONS

In summary, we discovered a potential relationship between IL24 and autophagy during PM_2.5 exposure. IL24 might be a novel potential biomarker or therapeutic target in PM_2.5 caused lung dysfunction through regulation of autophagy.

The interplay between oxidative stress and autophagy in chronic obstructive pulmonary disease

Autophagy is a highly conserved process that is indispensable for cell survival, embryonic development, and tissue homeostasis. Activation of autophagy protects cells against oxidative stress and is a major adaptive response to injury. When autophagy is dysregulated by factors such as smoking, environmental insults and aging, it can lead to enhanced formation of aggressors and production of reactive oxygen species (ROS), resulting in oxidative stress and oxidative damage to cells. ROS activates autophagy, which in turn promotes cell adaptation and reduces oxidative damage by degrading and circulating damaged macromolecules and dysfunctional cell organelles. The cellular response triggered by oxidative stress includes changes in signaling pathways that ultimately regulate autophagy. Chronic obstructive pulmonary disease (COPD) is the most common lung disease among the elderly worldwide, with a high mortality rate. As an induced response to oxidative stress, autophagy plays an important role in the pathogenesis of COPD. This review discusses the regulation of oxidative stress and autophagy in COPD, and aims to provide new avenues for future research on target-specific treatments for COPD.

APOE in the bullseye of neurodegenerative diseases: impact of the APOE genotype in Alzheimer's disease pathology and brain diseases

ApoE is the major lipid and cholesterol carrier in the CNS. There are three major human polymorphisms, apoE2, apoE3, and apoE4, and the genetic expression of APOE4 is one of the most influential risk factors for the development of late-onset Alzheimer's disease (AD). Neuroinflammation has become the third hallmark of AD, together with Amyloid-β plaques and neurofibrillary tangles of hyperphosphorylated aggregated tau protein. This review aims to broadly and extensively describe the differential aspects concerning apoE. Starting from the evolution of apoE to how APOE's single-nucleotide polymorphisms affect its structure, function, and involvement during health and disease. This review reflects on how APOE's polymorphisms impact critical aspects of AD pathology, such as the neuroinflammatory response, particularly the effect of APOE on astrocytic and microglial function and microglial dynamics, synaptic function, amyloid-β load, tau pathology, autophagy, and cell-cell communication. We discuss influential factors affecting AD pathology combined with the APOE genotype, such as sex, age, diet, physical exercise, current therapies and clinical trials in the AD field. The impact of the APOE genotype in other neurodegenerative diseases characterized by overt inflammation, e.g., alpha- synucleinopathies and Parkinson's disease, traumatic brain injury, stroke, amyotrophic lateral sclerosis, and multiple sclerosis, is also addressed. Therefore, this review gathers the most relevant findings related to the APOE genotype up to date and its implications on AD and CNS pathologies to provide a deeper understanding of the knowledge in the APOE field.

MERS-CoV ORF4b is a virulence factor involved in the inflammatory pathology induced in the lungs of mice

No vaccines or specific antiviral drugs are authorized against Middle East respiratory syndrome coronavirus (MERS-CoV) despite its high mortality rate and prevalence in dromedary camels. Since 2012, MERS-CoV has been causing sporadic zoonotic infections in humans, which poses a risk of genetic evolution to become a pandemic virus. MERS-CoV genome encodes five accessory proteins, 3, 4a, 4b, 5 and 8b for which limited information is available in the context of infection. This work describes 4b as a virulence factor in vivo, since the deletion mutant of a mouse-adapted MERS-CoV-Δ4b (MERS-CoV-MA-Δ4b) was completely attenuated in a humanized DPP4 knock-in mouse model, resulting in no mortality. Attenuation in the absence of 4b was associated with a significant reduction in lung pathology and chemokine expression levels at 4 and 6 days post-infection, suggesting that 4b contributed to the induction of lung inflammatory pathology. The accumulation of 4b in the nucleus in vivo was not relevant to virulence, since deletion of its nuclear localization signal led to 100% mortality. Interestingly, the presence of 4b protein was found to regulate autophagy in the lungs of mice, leading to upregulation of BECN1, ATG3 and LC3A mRNA. Further analysis in MRC-5 cell line showed that, in the context of infection, MERS-CoV-MA 4b inhibited autophagy, as confirmed by the increase of p62 and the decrease of ULK1 protein levels, either by direct or indirect mechanisms. Together, these results correlated autophagy activation in the absence of 4b with downregulation of a pathogenic inflammatory response, thus contributing to attenuation of MERS-CoV-MA-Δ4b.

Inflammation and Autophagy: A Convergent Point between Autism Spectrum Disorder (ASD)-Related Genetic and Environmental Factors: Focus on Aluminum Adjuvants

Autism spectrum disorder (ASD), schizophrenia, and bipolar disorder are genetically complex and heterogeneous neurodevelopmental disorders (NDDs) resulting from genetic factors and gene-environment (GxE) interactions for which onset occurs in early brain development. Recent progress highlights the link between ASD and (i) immunogenetics, neurodevelopment, and inflammation, and (ii) impairments of autophagy, a crucial neurodevelopmental process involved in synaptic pruning. Among various environmental factors causing risk for ASD, aluminum (Al)-containing vaccines injected during critical periods have received special attention and triggered relevant scientific questions. The aim of this review is to discuss the current knowledge on the role of early inflammation, immune and autophagy dysfunction in ASD as well as preclinical studies which question Al adjuvant impacts on brain and immune maturation. We highlight the most recent breakthroughs and the lack of epidemiological, pharmacokinetic and pharmacodynamic data constituting a "scientific gap". We propose additional research, such as genetic studies that could contribute to identify populations at genetic risk, improving diagnosis, and potentially the development of new therapeutic tools.

A Review of Signaling Transduction Mechanisms in Osteoclastogenesis Regulation by Autophagy, Inflammation, and Immunity

Osteoclastogenesis is an ongoing rigorous course that includes osteoclast precursors fusion and bone resorption executed by degradative enzymes. Osteoclastogenesis is controlled by endogenous signaling and/or regulators or affected by exogenous conditions and can also be controlled both internally and externally. More evidence indicates that autophagy, inflammation, and immunity are closely related to osteoclastogenesis and involve multiple intracellular organelles (e.g., lysosomes and autophagosomes) and certain inflammatory or immunological factors. Based on the literature on osteoclastogenesis induced by different regulatory aspects, emerging basic cross-studies have reported the emerging disquisitive orientation for osteoclast differentiation and function. In this review, we summarize the partial potential therapeutic targets for osteoclast differentiation and function, including the signaling pathways and various cellular processes.

Sex and APOE Genotype Alter the Basal and Induced Inflammatory States of Primary Microglia from APOE Targeted Replacement Mice

The sex and APOE4 genotype are significant risk factors for Alzheimer’s disease (AD); however, the mechanism(s) responsible for this interaction are still a matter of debate. Here, we assess the responses of mixed-sex and sex-specific APOE3 and APOE4 primary microglia (PMG) to lipopolysaccharide and interferon-gamma. In our investigation, inflammatory cytokine profiles were assessed by qPCR and multiplex ELISA assays. Mixed-sex APOE4 PMG exhibited higher basal mRNA expression and secreted levels of TNFa and IL1b. In sex-specific cultures, basal expression and secreted levels of IL1b, TNFa, IL6, and NOS2 were 2−3 fold higher in APOE4 female PMG compared to APOE4 males, with both higher than APOE3 cells. Following an inflammatory stimulus, the expression of pro-inflammatory cytokines and the secreted cytokine level were upregulated in the order E4 female > E4 male > E3 female > E3 male in sex-specific cultures. These data indicate that the APOE4 genotype and female sex together contribute to a greater inflammatory response in PMG isolated from targeted replacement humanized APOE mice. These data are consistent with clinical data and indicate that sex-specific PMG may provide a platform for exploring mechanisms of genotype and sex differences in AD related to neuroinflammation and neurodegeneration.

Autophagy-Mediated Inflammatory Cytokine Secretion in Sporadic ALS Patient iPSC-Derived Astrocytes

Background. Astrocytes can be involved in motor neuron toxicity in amyotrophic lateral sclerosis (ALS) induced by noncell autonomous effects, and inflammatory cytokines may play the main role in mediating this process. However, the etiology of aberrant cytokine secretion is unclear. The present study assessed possible involvement of the mTOR-autophagy pathway in aberrant cytokine secretion by ALS patient iPSC-derived astrocytes. Method and Results. PBMCs from sporadic ALS patients and control subjects were reprogrammed into iPSCs, which were then differentiated into astrocytes and/or motor neurons. Comparison with control astrocytes indicated that conditioned medium of ALS astrocytes reduced the viability of the control motor neurons ( $p<0.05$ ) assessed using the MTT assay. The results of ELISA showed that the concentrations of TNFα, IL1β, and IL6 in cell culture medium of ALS astrocytes were increased ( $p<0.05$ ). ALS astrocytes had higher p62 and mTOR levels and lower LC3BII/LC3BI ratio and ULK1 and p-Beclin-1 (Ser15) levels ( $p<0.05$ ), indicating defective autophagy. Exogenous inhibition of the mTOR-autophagy pathway, but not the activation of the pathway in control subject astrocytes, increased the levels of p62 and mTOR and concentration of IL-1β, TNF-α, and IL-6 in cell culture medium and decreased the LC3BII/LC3BI ratio and levels of ULK1 and p-Beclin-1 (Ser15), and these changes were comparable to those in ALS astrocytes. After 48 h of rapamycin (autophagy activator) and 3-methyladenine (autophagy inhibitor) treatments, the exogenous activation of the mTOR-autophagy pathway, but not inhibition of the pathway, in ALS astrocytes significantly reduced the concentrations of TNFα, IL1β, and IL6 in cell culture medium and reduced the levels of p62, while increasing the levels of LC3B-II/LC3B-I, ULK1, and p-Beclin-1 (Ser15), and these changes were comparable to those in control subject astrocytes. Conclusion. Alteration in the mTOR/ULK1/Beclin-1 pathway regulated cytokine secretion in ALS astrocytes, which was able to lead to noncell autonomous toxicity. Autophagy activation mitigated cytokine secretion by ALS astrocytes.

ZC3H4 regulates infiltrating monocytes, attenuating pulmonary fibrosis through IL-10

Silicosis is a pulmonary fibrosis-associated disease caused by the inhalation of large amounts of free silicon dioxide (SiO₂) that mainly manifests as early inflammation and late pulmonary fibrosis. As macrophage precursors, monocytes accumulate in the lung during early inflammation, but their role in the development of silicosis is unclear. Single-cell sequencing (cell numbers = 25,002), Western blotting, quantitative real-time PCR, ELISA and cell functional experiments were used to explore the specific effects of monocytes on fibroblasts. The CRISPR/Cas9 system was used to specifically knock down ZC3H4, a novel member of the CCCH zinc finger protein family, and was combined with pharmacological methods to explore the mechanism by which ZC3H4 affects chemokine and cytokine secretion. The results indicated that (1) SiO₂ induced an infiltrating phenotype in monocytes; (2) infiltrating monocytes inhibited the activation, viability and migration of fibroblasts by regulating IL-10 but not IL-8; and (3) SiO₂ downregulated IL-10 via ZC3H4-induced autophagy. This study revealed that ZC3H4 regulated the secretion function of monocytes, which, in turn, inhibited fibroblast function in early inflammation through autophagy signaling, thereby reducing pulmonary fibrosis. These findings provide a new idea for the clinical treatment of silicosis.

Genome-wide association study identifies Sjögren's risk loci with functional implications in immune and glandular cells

Sjögren's disease is a complex autoimmune disease with twelve established susceptibility loci. This genome-wide association study (GWAS) identifies ten novel genome-wide significant (GWS) regions in Sjögren's cases of European ancestry: CD247, NAB1, PTTG1-MIR146A, PRDM1-ATG5, TNFAIP3, XKR6, MAPT-CRHR1, RPTOR-CHMP6-BAIAP6, TYK2, SYNGR1. Polygenic risk scores yield predictability (AUROC = 0.71) and relative risk of 12.08. Interrogation of bioinformatics databases refine the associations, define local regulatory networks of GWS SNPs from the 95% credible set, and expand the implicated gene list to >40. Many GWS SNPs are eQTLs for genes within topologically associated domains in immune cells and/or eQTLs in the main target tissue, salivary glands.

Surface layer protein A from hypervirulent Clostridioides difficile ribotype 001 can induce autophagy process in human intestinal epithelial cells

Clostridioides difficile is the leading cause of nosocomial diarrhea with high morbidity and mortality worldwide. C. difficile strains produce a crystalline surface layer protein A (SlpA), which is an absolute necessity for its pathogenesis. However, its pathogenic mechanisms and its pro-inflammatory behavior are not yet fully elucidated. Herein, we report for the first time that SlpA extracted from C. difficile can induce autophagy process in Caco-2 cells. SlpA protein was purified from two C. difficile strains (RT001 and ATCC 700075). The cell viability of Caco-2 cells after exposure with different concentrations (15, 20, 25 μg/mL) of SlpA at various time points (3, 6, 12, 24 h) was measured by MTT assay. Acridine orange staining was used to visualize the hypothetical acidic vesicular organelles. The gene expression of autophagy mediators including LC3B, Atg5, Atg16L, and Beclin-1 was determined by quantitative real-time PCR assay. Western blotting assay was used to detect the expression of LC3B protein. MTT assay showed that different concentrations of SlpA did not induce significant changes in the viability of Caco-2 cells. SlpA at concentration of 20 μg/mL enhanced the formation of acidic vesicular organelles in Caco-2 cells after 12 h of exposure. Moreover, SlpA treatment significantly increased the expression of autophagy-associated genes, and increased the expression of LC3B protein in Caco-2 cells. In conclusion, our study demonstrated that SlpA is capable to induce autophagy in intestinal epithelial cells. These findings reveal a novel mechanism for the pathogenesis of C. difficile mediated by its SLPs.

Targeting autophagy and neuroinflammation pathways with plant-derived natural compounds as potential antidepressant agents

Major depressive disorder (MDD) is a life-threatening disease that presents several characteristics. The pathogenesis of depression still remains poorly understood. Moreover, the mechanistic interactions of natural components in treating depression to target autophagy and neuroinflammation are yet to be evaluated. This study overviewed the effects of plant-derived natural components in regulating critical pathways, particularly neuroinflammation and autophagy, associated with depression. A list of natural components, including luteolin, apigenin, hyperforin, resveratrol, salvianolic acid b, isoliquiritin, nobiletin, andrographolide, and oridonin, have been investigated. All peer-reviewed journal articles were searched by Scopus, MEDLINE, PubMed, Web of Science, and Google Scholar using the appropriated keywords, including depression, neuroinflammation, autophagy, plant, natural components, etc. The neuroinflammation and autophagy dysfunction are critically associated with the pathophysiology of depression. Natural components with higher efficiency and lower complications can be used for targeting neuroinflammation and autophagy. These components with different doses showed the beneficial antidepressant properties in rodents. These can modulate autophagy markers, mainly AMPK, LC3II/LC3I ratio, Beclin-1. Moreover, they can regulate the NLRP3 inflammasome, resulting in the suppression of proinflammatory cytokines (e.g., IL-1β and IL-18). Future in vitro and in vivo studies are required to develop novel therapeutic approaches based on plant-derived active components to treat MDD.

The interactive role of inflammatory mediators and metabolic reprogramming in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by its highly reactive inflammatory desmoplastic stroma with evidence of an extensive tumor stromal interaction largely mediated by inflammatory factors. KRAS mutation and inflammatory signaling promote protumorigenic events, including metabolic reprogramming with several inter-regulatory crosstalks to fulfill the high demand of energy and regulate oxidative stress for tumor growth and progression. Notably, the more aggressive molecular subtype of PDAC enhances influx of glycolytic intermediates. This review focuses on the interactive role of inflammatory signaling and metabolic reprogramming with emerging evidence of crosstalk, which supports the development, progression, and therapeutic resistance of PDAC. Understanding the emerging crosstalk between inflammation and metabolic adaptations may identify potential targets and develop novel therapeutic approaches for PDAC.

Transcriptome analysis uncovers the autophagy-mediated regulatory patterns of the immune microenvironment in dilated cardiomyopathy

The relationship between autophagy and immunity has been well studied. However, little is known about the role of autophagy in the immune microenvironment during the progression of dilated cardiomyopathy (DCM). Therefore, this study aims to uncover the effect of autophagy on the immune microenvironment in the context of DCM. By investigating the autophagy gene expression differences between healthy donors and DCM samples, 23 dysregulated autophagy genes were identified. Using a series of bioinformatics methods, 13 DCM‐related autophagy genes were screened and used to construct a risk prediction model, which can well distinguish DCM and healthy samples. Then, the connections between autophagy and immune responses including infiltrated immunocytes, immune reaction gene‐sets and human leukocyte antigen (HLA) genes were systematically evaluated. In addition, two autophagy‐mediated expression patterns in DCM were determined via the unsupervised consensus clustering analysis, and the immune characteristics of different patterns were revealed. In conclusion, our study revealed the strong effect of autophagy on the DCM immune microenvironment and provided new insights to understand the pathogenesis and treatment of DCM.

Tracking autophagy process with a through bond energy transfer-based ratiometric two-photon viscosity probe

Autophagy is a self-degradation process in cells, which is of vital significance to the health and operation of organisms. Due to the increase of lysosomal viscosity during autophagy, viscosity probes that specifically accumulate in lysosome are powerful tools for monitoring autophagy and investigating related diseases. However, there is still a lack of viscosity-sensitive ratiometric autophagy probes, which restricts the tracking of autophagy with high accuracy in complex physiological environment. Herein, a viscosity-responsive, lysosome targeted two-photon fluorescent probe Lyso-Vis was designed based on through bond energy transfer (TBET) mechanism. The TBET-based probe achieved the separation of two emission baselines, which greatly improved the resolution and reliability of sensing and imaging. Under 810 nm two-photon excitation, the emission intensity ratio of the red and green channel increased with a viscosity dependent manner. Lyso-Vis not only for the first time realized ratiometric sensing of lysosomal viscosity during autophagy process, but also visualized the association of autophagy with inflammation and stroke, and it was applied to explore the activation and inhibition of autophagy during stroke in mice.

The role of autophagy in initiation, progression, TME modification, diagnosis, and treatment of esophageal cancers

Autophagy is a highly conserved metabolic process with a cytoprotective function. Autophagy is involved in cancer, infection, immunity, and inflammation and may be a potential therapeutic target. Increasing evidence has revealed that autophagy has primary implications for esophageal cancer, including its initiation, progression, tumor microenvironment (TME) modification, diagnosis, and treatment. Notably, autophagy displayed excellent application potential in radiotherapy combined with immunotherapy. Radiotherapy combined with immunotherapy is a new potential therapeutic strategy for cancers, including esophageal cancer. Autophagy modulators can work as adjuvant enhancers in radiotherapy or immunotherapy of cancers. This review highlights the most recent data related to the role of autophagy regulation in esophageal cancer.

Autophagy and Skin Diseases

Autophagy is a highly conserved lysosomal degradation system that involves the creation of autophagosomes, which eventually fuse with lysosomes and breakdown misfolded proteins and damaged organelles with their enzymes. Autophagy is widely known for its function in cellular homeostasis under physiological and pathological settings. Defects in autophagy have been implicated in the pathophysiology of a variety of human diseases. The new line of evidence suggests that autophagy is inextricably linked to skin disorders. This review summarizes the principles behind autophagy and highlights current findings of autophagy's role in skin disorders and strategies for therapeutic modulation.

Crosstalk Between ROS and Autophagy in Tumorigenesis: Understanding the Multifaceted Paradox

Cancer formation is a highly regulated and complex process, largely dependent on its microenvironment. This complexity highlights the need for developing novel target-based therapies depending on cancer phenotype and genotype. Autophagy, a catabolic process, removes damaged and defective cellular materials through lysosomes. It is activated in response to stress conditions such as nutrient deprivation, hypoxia, and oxidative stress. Oxidative stress is induced by excess reactive oxygen species (ROS) that are multifaceted molecules that drive several pathophysiological conditions, including cancer. Moreover, autophagy also plays a dual role, initially inhibiting tumor formation but promoting tumor progression during advanced stages. Mounting evidence has suggested an intricate crosstalk between autophagy and ROS where they can either suppress cancer formation or promote disease etiology. This review highlights the regulatory roles of autophagy and ROS from tumor induction to metastasis. We also discuss the therapeutic strategies that have been devised so far to combat cancer. Based on the review, we finally present some gap areas that could be targeted and may provide a basis for cancer suppression.

3,4-Dihydroxyphenylethanol (DPE or Hydroxytyrosol) Counteracts ERK1/2 and mTOR Activation, Pro-Inflammatory Cytokine Release, Autophagy and Mitophagy Reduction Mediated by Benzo[a]pyrene in Primary Human Colonic Epithelial Cells

Understanding the effects induced by carcinogens on primary colonic epithelial cells and how to counteract them might help to prevent colon cancer, which is one of the most frequent and aggressive cancers. In this study, we exposed primary human colonic epithelial cells (HCoEpC) to Benzo[a]pyrene (B[a]P) and found that it led to an increased production of pro-inflammatory cytokines and activated ERK1/2 and mTOR. These pathways are known to be involved in inflammatory bowel disease (IBD), which represents a colon cancer risk factor. Moreover, B[a]P reduced autophagy and mitophagy, processes whose dysregulation has been clearly demonstrated to predispose to cancer either by in vitro or in vivo studies. Interestingly, all the effects induced by B[a]P could be counteracted by 3,4-Dihydroxyphenylethanol (DPE or Hydroxytyrosol, H), the most powerful anti-inflammatory and antioxidant compound contained in olive oil. This study sheds light on the mechanisms that could be involved in colon carcinogenesis induced by a chemical carcinogen and identifies a safe natural product that may help to prevent them.

Combined Effects of Fludarabine and Interferon Alpha on Autophagy Regulation Define the Phase of Cell Survival and Promotes Responses in LLC-MK2 and K562 Cells

Autophagy is a known mechanism of cells under internal stress that regulates cellular function via internal protein recycling and the cleaning up of debris, leading to healthy live cells. However, the stimulation of autophagy by external factors such as chemical compounds or viral infection mostly tends to induce apoptosis/cell death. This study hypothesizes that manipulation of the autophagy mechanism to the pro-cell survival and/or decreased pro-viral niche can be a strategy for effective antiviral and anticancer treatment. Cells susceptible to viral infection, namely LLC-MK2, normal monkey epithelium, and K562, human immune-related lymphocyte, which is also a cancer cell line, were treated with fludarabine nucleoside analog (Fdb), interferon alpha (IFN-α), and a combination of Fdb and IFN-α, and then were evaluated for signs of adaptive autophagy and STAT1 antiviral signaling by Western blotting and immunolabeling assays. The results showed that the low concentration of Fdb was able to activate an autophagy response in both cell types, as demonstrated by the intense immunostaining of LC3B foci in the autophagosomes of living cells. Treatment with IFN-α (10 U/mL) showed no alteration in the initiator of mTOR autophagy but dramatically increased the intracellular STAT1 signaling molecules in both cell types. Although in the combined Fdb and IFN-α treatment, both LLC-MK2 and K562 cells showed only slight changes in the autophagy-responsive proteins p-mTOR and LC3B, an adaptive autophagy event was clearly shown in the autophagosome of the LLC-MK2 cell, suggesting the survival phase of the normal cell. The combined effect of Fdb and IFN-α treatment on the antiviral response was identified by the level of activation of the STAT1 antiviral marker. Significantly, the adaptive autophagy mediated by Fdb was able to suppress the IFN-α-mediated pSTAT1 signaling in both cell types to a level that is appropriate for cellular function. It is concluded that the administration of an appropriate dose of Fdb and IFN-α in combination is beneficial for the treatment of some types of cancer and viral infection.

The Role of Autophagy and Apoptosis in Neuropathic Pain Formation

Neuropathic pain indicates pain caused by damage to the somatosensory system and is difficult to manage and treat. A new treatment strategy urgently needs to be developed. Both autophagy and apoptosis are critical adaptive mechanisms when neurons encounter stress or damage. Recent studies have shown that, after nerve damage, both autophagic and apoptotic activities in the injured nerve, dorsal root ganglia, and spinal dorsal horn change over time. Many studies have shown that upregulated autophagic activities may help myelin clearance, promote nerve regeneration, and attenuate pain behavior. On the other hand, there is no direct evidence that the inhibition of apoptotic activities in the injured neurons can attenuate pain behavior. Most studies have only shown that agents can simultaneously attenuate pain behavior and inhibit apoptotic activities in the injured dorsal root ganglia. Autophagy and apoptosis can crosstalk with each other through various proteins and proinflammatory cytokine expressions. Proinflammatory cytokines can promote both autophagic/apoptotic activities and neuropathic pain formation, whereas autophagy can inhibit proinflammatory cytokine activities and further attenuate pain behaviors. Thus, agents that can enhance autophagic activities but suppress apoptotic activities on the injured nerve and dorsal root ganglia can treat neuropathic pain. Here, we summarized the evolving changes in apoptotic and autophagic activities in the injured nerve, dorsal root ganglia, spinal cord, and brain after nerve damage. This review may help in further understanding the treatment strategy for neuropathic pain during nerve injury by modulating apoptotic/autophagic activities and proinflammatory cytokines in the nervous system.

Molecular Mechanisms of Immunosenescene and Inflammaging: Relevance to the Immunopathogenesis and Treatment of Multiple Sclerosis

Aging is characterized, amongst other features, by a complex process of cellular senescence involving both innate and adaptive immunity, called immunosenescence and associated to inflammaging, a low-grade chronic inflammation. Both processes fuel each other and partially explain increasing incidence of cancers, infections, age-related autoimmunity, and vascular disease as well as a reduced response to vaccination. Multiple sclerosis (MS) is a lifelong disease, for which considerable progress in disease-modifying therapies (DMTs) and management has improved long-term survival. However, disability progression, increasing with age and disease duration, remains. Neurologists are now involved in caring for elderly MS patients, with increasing comorbidities. Aging of the immune system therefore has relevant implications for MS pathogenesis, response to DMTs and the risks mediated by these treatments. We propose to review current evidence regarding markers and molecular mechanisms of immunosenescence and their relevance to understanding MS pathogenesis. We will focus on age-related changes in the innate and adaptive immune system in MS and other auto-immune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. The consequences of these immune changes on MS pathology, in interaction with the intrinsic aging process of central nervous system resident cells will be discussed. Finally, the impact of immunosenescence on disease evolution and on the safety and efficacy of current DMTs will be presented.

mTOR signaling as a molecular target for the alleviation of Alzheimer's disease pathogenesis

Mechanistic/mammalian target of rapamycin (mTOR) belongs to the phosphatidylinositol kinase-related kinase (PIKK) family. mTOR signaling is required for the commencement of essential cell functions including autophagy. mTOR primarily governs cell growth in response to favourable nutrients and other growth stimuli. However, it also influences aging and other aspects of nutrient-related physiology such as protein synthesis, ribosome biogenesis, and cell proliferation in adults with very limited growth. The major processes for survival such as synaptic plasticity, memory storage and neuronal recovery involve a significant mTOR activity. mTOR dysregulation is becoming a prevalent motif in a variety of human diseases, including cancer, neurological disorders, and other metabolic syndromes. The use of rapamycin to prolong life in different animal models may be attributable to the multiple roles played by mTOR signaling in various processes involved in ageing, protein translation, autophagy, stem cell pool turnover, inflammation, and cellular senescence. mTOR activity was found to be altered in AD brains and rodent models, supporting the notion that aberrant mTOR activity is one of the key events contributing to the onset and progression of AD hallmarks This review assesses the molecular association between the mTOR signaling pathway and pathogenesis of Alzheimer's disease. The research data supporting this theme are also reviewed.

Construction of an Immune-Autophagy Prognostic Model Based on ssGSEA Immune Scoring Algorithm Analysis and Prognostic Value Exploration of the Immune-Autophagy Gene in Endometrial Carcinoma (EC) Based on Bioinformatics

BACKGROUND

Endometrial carcinoma (EC) is a malignant cancer spreading worldwide and in the fourth position among all other types of cancer in women. The purpose of this paper is to explore the prognostic value of the immune-autophagy gene in endometrial carcinoma (EC) based on bioinformatics, construct an immune-autophagy prognostic model of endometrial carcinoma, search for independent prognostic markers, and finally predict the potential therapeutic drugs of TCGA subgroup.

METHODS

The Cancer Genome Atlas (TCGA) database was used to extract transcriptome sequencing data of patients suffering from EC; 28 kinds of immune cells were scored by ssGSEA, and the immune subtypes were grouped by consistency cluster analysis. The accuracy and effectiveness of the grouping were verified by the analysis of differential gene expression and survival rate of immune checkpoints in the two groups to provide the premise and basis for the establishment of independent prognostic factors. The expression of different genes in high and low immune groups was analyzed. The analysis of various genes' expression in immune groups (high and low) has been performed. Go function annotation and KEGG pathway enrichment analysis were used to evaluate the difference of immune infiltration between high and low immune groups. The immune and autophagy genes were crossed, the key (hub) genes were selected, the risk was scored, the prognosis model was constructed, and the independent prognostic markers were established. CAMP and CTRP 2.0 were used to test the drug sensitivity.

RESULTS

According to the level of immune cell enrichment, the results have been subcategorized into two immune subtypes: high immunity group_ H and low immunity group_ L. Two immune subtypes, CD274, PDCD1, and CTLA4, were detected in the immune system_ H and immunity_L. A significant difference was detected between these two groups in the expression and survival rate. Few more differences were also detected between the two groups through the evaluation of immune infiltration, which proved the grouping's accuracy and effectiveness. Differential gene expression analysis showed that there were 721 DEGs and 3 hub genes. DEGs are mainly involved in lymphocyte activation, proliferation, differentiation, leukocyte proliferation, and other biological processes, mediate chemokines' activities, chemokine receptor binding, and other molecular functions, and are enriched in the outer plasma membrane, endoplasmic reticulum, and T cell receptor complex. The enriched pathways are allograft, complex, inflammatory, interferon-alpha, interferon-gamma, E2F, G2M, mitotic, etc.

CONCLUSION

Through bioinformatics analysis, we successfully constructed the immuno-autophagy prognosis model of endometrial cancer and identified three high-risk immunoautophagy genes, including VEGFA, CCL2, and Ifng. Four potential therapeutic drugs were predicted as sildenafil, sunitinib, TPCA-1, and etoposide.