The Interplay Between Pattern Recognition Receptors and Autophagy in Inflammation

The complex interplay between encephalomyocarditis virus and the host defence system

A variety of animals can be infected by encephalomyocarditis virus (EMCV). EMCV is the established causative agent of myocarditis and encephalitis in some animals. EMCV causes high fatality in suckling and weaning piglets, making pigs the most susceptible domestic animal species. Importantly, EMCV has zoonotic potential to infect the human population. The ability of the pathogen to avoid and undermine the initial defence mechanism of the host contributes to its virulence and pathogenicity. A large body of literature highlights the intricate strategies employed by EMCV to escape the innate immune machinery to suit its "pathogenic needs." Here, we also provide examples on how EMCV interacts with certain host proteins to dampen the infection process. Hence, this concise review aims to summarize these findings in a compendium of decades of research on this exciting yet underappreciated topic.

AIM2 enhances Candida albicans infection through promoting macrophage apoptosis via AKT signaling

Candida albicans is among the most prevalent invasive fungal pathogens for immunocompromised individuals and novel therapeutic approaches that involve immune response modulation are imperative. Absent in melanoma 2 (AIM2), a pattern recognition receptor for DNA sensing, is well recognized for its involvement in inflammasome formation and its crucial role in safeguarding the host against various pathogenic infections. However, the role of AIM2 in host defense against C. albicans infection remains uncertain. This study reveals that the gene expression of AIM2 is induced in human and mouse innate immune cells or tissues after C. albicans infection. Furthermore, compared to their wild-type (WT) counterparts, Aim2-/- mice surprisingly exhibit resistance to C. albicans infection, along with reduced inflammation in the kidneys post-infection. The resistance of Aim2-/- mice to C. albicans infection is not reliant on inflammasome or type I interferon production. Instead, Aim2-/- mice display lower levels of apoptosis in kidney tissues following infection than WT mice. The deficiency of AIM2 in macrophages, but not in dendritic cells, results in a phenocopy of the resistance observed in Aim2-/- mice against C. albican infection. The treatment of Clodronate Liposome, a reagent that depletes macrophages, also shows the critical role of macrophages in host defense against C. albican infection in Aim2-/- mice. Furthermore, the reduction in apoptosis is observed in Aim2-/- mouse macrophages following infection or treatment of DNA from C. albicans in comparison with controls. Additionally, higher levels of AKT activation are observed in Aim2-/- mice, and treatment with an AKT inhibitor reverses the host resistance to C. albicans infection. The findings collectively demonstrate that AIM2 exerts a negative regulatory effect on AKT activation and enhances macrophage apoptosis, ultimately compromising host defense against C. albicans infection. This suggests that AIM2 and AKT may represent promising therapeutic targets for the management of fungal infections.

Xijiao Dihuang decoction combined with Yinqiao powder promotes autophagy-dependent ROS decrease to inhibit ROS/NLRP3/pyroptosis regulation axis in influenza virus infection

BACKGROUND

Influenza viral pneumonia is a common complication after influenza virus infection. Xijiao Dihuang Decoction combined with Yinqiao Powder (XDY) is effective on improving influenza viral pneumonia.

PURPOSE

This study further explores the anti-inflammatory mechanism of XDY in the treatment of influenza viral pneumonia.

STUDY DESIGN

The effects of XDY on inflammation, autophagy, NACHT-LRR-PYD-containing protein 3 (NLRP3) inflammasome and pyroptosis were assessed in the mice with influenza viral pneumonia. In addition, the mouse macrophage cell line (J774A.1) infected with influenza virus was adopted to decode the in vitro effects of XDY on autophagy, reactive oxygen species (ROS), NLRP3 inflammasome and pyroptosis. We analyzed the XDY-induced autophagy, especially the mitophagy-related ROS clearance, and the subsequent inhibition of ROS/NLRP3 inflammasome/pyroptosis signaling in the infected macrophages by different assays based on quantitative polymerase chain reaction, western blot, flow cytometry, immunofluorescence and enzyme-linked immunosorbent assay.

RESULTS

In vivo, XDY could effectively improve the lung inflammatory response in the mice with influenza virus pneumonia, due to an intact autophagy flux-promoting effect and the inhibiting roles on NLRP3 inflammasome and pyroptosis. Notably, in vitro, compared with the infected macrophages treated by the NLRP3 inflammasome agonist (Monosodium urate) or the mitochondrial-targeted antioxidant agent, the XDY-dependent treating could inhibit pyroptosis by negatively regulating the signaling axis of ROS/NLRP3 inflammasome/pyroptosis in the influenza virus-infected macrophages. More interestingly, XDY could promote an intact autophagy flux, inducing mitophagy eliminating the damaged mitochondria to reduce the intracellular ROS accumulation, and thus decrease the oxidative stress in the infected macrophages. Especially, the inhibitor of autophagy inition, 3-Methyladenine, could reverse the inhibitory effect of XDY on ROS-NLRP3 inflammasome-mediated pyroptosis, indicating an XDY-promoted mitophagy-dependent ROS scavenging.

CONCLUSION

XDY can promote an intact autophagy flux to eliminate damaged mitochondria, namely mitophagy, which reduces the intracellular ROS accumulation contributing to NLRP3 inflammasome activation, restricting pyroptosis and eventually alleviating the influenza virus-induced inflammatory lesions. The obtained results provide new insights into the mechanism of action of XDY in alleviating influenza virus pneumonia, especially the roles of XDY in anti-oxidation, anti-inflammation and anti-pyroptosis, with potential therapeutic targets for future application in integrative medicine.

Platycodon grandiflorus polysaccharide inhibits the inflammatory response of 3D4/21 cells infected with PCV2

Porcine circovirus type 2 (PCV2) infection cause multi-systemic inflammation in pigs. Platycodon grandiflorus polysaccharide (PGPSt) has been reported to have the effects of immune regulation and disease resistance. Nevertheless, the role and mechanism of PGPSt in the inflammatory response of 3D4/21 cells induced by PCV2 infection remain unclear. The present study aims to investigate effects of PGPSt on inflammatory response and its possible underlying mechanisms in vitro models. Cells were treated with PCV2 for 36 h to construct a cell inflammation model. The 3D4/21 cell lines were pretreated with or without PGPSt, and the changes of inflammation-related markers and the signaling pathway were detected by CCK-8, ELISA, qPCR and Western blot. The results showed that PGPSt was non-toxic to cells and protected PCV2-infected cells from inflammatory damage. PGPSt could significantly inhibit the high acetylation of histone H3 (AcH3) and histone H4 (AcH4), down-regulate HAT and up-regulate HDAC activity, and reduce the expression of pro-inflammatory enzymes iNOS and COX-2 proteins levels. Then the levels of IL-1β, IL-6 and TNF-α were significantly inhibited, and the level of IL-10 was promoted. We also observed that PGPSt inhibited the phosphorylation of p65, p38 and Erk1/2, which subsequently inhibited nuclear translocation of NF-κB p65 to express pro-inflammatory factors. In conclusion, PGPSt can reduce the inflammatory response by regulating histone acetylation, reducing the release of inflammatory factors, reducing the expression of pro-inflammatory enzymes, and inhibiting the activation of NF-κB and MAPKs signaling pathways. This suggests that PGPSt had an anti-inflammatory effect on the inflammatory response caused by PCV2 infection, which provided theoretical data support for the research.

BRCC3 mediates inflammation and pyroptosis in cerebral ischemia/reperfusion injury by activating the NLRP6 inflammasome

AIMS

Neuroinflammation and pyroptosis are key mediators of cerebral ischemia/reperfusion (I/R) injury-induced pathogenic cascades. BRCC3, the human homolog of BRCC36, is implicated in neurological disorders and plays a crucial role in neuroinflammation and pyroptosis. However, its effects and potential mechanisms in cerebral I/R injury in mice are unclear.

METHODS

Cellular localization of BRCC3 and the interaction between BRCC3 and NLRP6 were assessed. Middle cerebral artery occlusion/reperfusion (MCAO) and oxygen-glucose deprivation/reoxygenation (OGD/R) models were established in mice and HT22 cells, respectively, to simulate cerebral I/R injury in vivo and in vitro.

RESULTS

BRCC3 protein expression peaked 24 h after MCAO and OGD/R. BRCC3 knockdown reduced the inflammation and pyroptosis caused by cerebral I/R injury and ameliorated neurological deficits in mice after MCAO. The effects of BRCC3 on inflammation and pyroptosis may be mediated by NLRP6 inflammasome activation. Moreover, both BRCC3 and its N- and C-terminals interacted with NLRP6, and both BRCC3 and its terminals reduced NLRP6 ubiquitination. Additionally, BRCC3 affected the interaction between NLRP6 and ASC, which may be related to inflammasome activation.

CONCLUSION

BRCC3 shows promise as a novel target to enhance neurological recovery and attenuate the inflammatory responses and pyroptosis caused by NLRP6 activation in cerebral I/R injury.

Pharmacological induction of autophagy reduces inflammation in macrophages by degrading immunoproteasome subunits

Defective autophagy is linked to proinflammatory diseases. However, the mechanisms by which autophagy limits inflammation remain elusive. Here, we found that the pan-FGFR inhibitor LY2874455 efficiently activated autophagy and suppressed expression of proinflammatory factors in macrophages stimulated by lipopolysaccharide (LPS). Multiplex proteomic profiling identified the immunoproteasome, which is a specific isoform of the 20s constitutive proteasome, as a substrate that is degraded by selective autophagy. SQSTM1/p62 was found to be a selective autophagy-related receptor that mediated this degradation. Autophagy deficiency or p62 knockdown blocked the effects of LY2874455, leading to the accumulation of immunoproteasomes and increases in inflammatory reactions. Expression of proinflammatory factors in autophagy-deficient macrophages could be reversed by immunoproteasome inhibitors, confirming the pivotal role of immunoproteasome turnover in the autophagy-mediated suppression on the expression of proinflammatory factors. In mice, LY2874455 protected against LPS-induced acute lung injury and dextran sulfate sodium (DSS)-induced colitis and caused low levels of proinflammatory cytokines and immunoproteasomes. These findings suggested that selective autophagy of the immunoproteasome was a key regulator of signaling via the innate immune system.

Advances in the understanding of circRNAs that influence viral replication in host cells

Circular RNAs (circRNAs) are non-coding RNAs discovered in recent years, which are produced by back-splicing involving the 3' and 5' ends of RNA molecules. There is increasing evidence that circRNAs have important roles in cancer, neurological diseases, cardiovascular and cerebrovascular diseases, and other diseases. In addition, host circRNAs and virus-encoded circRNAs participate in the body's immune response, with antiviral roles. This review summarizes the mechanisms by which host and viral circRNAs interact during the host immune response. Comprehensive investigations have revealed that host circRNAs function as miRNA sponges in a particular manner, primarily by inhibiting viral replication. Viral circRNAs have more diverse functions, which generally involve promoting viral replication. In addition, in contrast to circRNAs from RNA viruses, circRNAs from DNA viruses can influence host cell migration, proliferation, and apoptosis, along with their effects on viral replication. In summary, circRNAs have potential as diagnostic and therapeutic targets, offering a foundation for the diagnosis and treatment of viral diseases.

Identification of pattern recognition receptor genes in peripheral blood mononuclear cells and monocytes as biomarkers for the diagnosis of lupus nephritis

BACKGROUND

The study aimed to investigate the diagnostic value of lupus-related pattern recognition receptors (PRRs) genes in peripheral blood mononuclear cells (PBMCs) and monocytes (MONs) for lupus nephritis (LN).

METHODS

PBMCs were isolated from a cohort with 37 LN patients and 39 healthy controls (HCs), and MONs were derived from another cohort with 70 LN patients and 66 HCs. Q-PCR was used to measure the mRNA levels of CGAS, IFNB1, AIM2, IL1Β, NLRC4, NLRP3, NLRP12 and ZBP1 in the PBMCs and MONs. The Mann-Whitney U test was used to compare the data in LN patients and HCs. Eleven GEO datasets of SLE/LN were used to perform differentially expressed genes (DEGs) analysis to these PRR genes. Receiver operating characteristic (ROC) curve analysis was employed to assess the performance of individual genes or the disease prediction model established by combining multiple genes in LN diagnosis. Spearman correlation method was done to analyze the correlation between these PRRs and other clinical characteristics.

RESULTS

The mRNA levels of five genes (AIM2, NLRC4, IL1B, NLRP12 and ZBP1) in PBMCs, and seven genes (CGAS, IFNB1, AIM2, IL1B, NLRP3, NLRP12 and ZBP1) in MONs of LN patients were significantly higher than those of HCs (P < 0.05). DEGs analysis based on the GEO datasets showed that ZBP1, AIM2 and IL1B were significantly increased in several datasets. The ROC curve analysis indicated that the area under curve (AUC) of the LN prediction models derived from PBMCs or MONs were 0.82 or 0.91 respectively. In addition, the expression levels of these PRRs were correlated with other clinical features in LN patients, including Anti-Sm, ESR, serum Cr, and C3.

CONCLUSION

Our study suggests that these lupus-related PRRs might be served as potential biomarkers of LN.

Integrated analysis of miRNA-mRNA expression of newly emerging swine H3N2 influenza virus cross-species infection with tree shrews

BACKGROUND

Cross-species transmission of zoonotic IAVs to humans is potentially widespread and lethal, posing a great threat to human health, and their cross-species transmission mechanism has attracted much attention. miRNAs have been shown to be involved in the regulation of IAVs infection and immunity, however, few studies have focused on the molecular mechanisms underlying miRNAs and mRNAs expression after IAVs cross-species infection.

METHODS

We used tree shrews, a close relative of primates, as a model and used RNA-Seq and bioinformatics tools to analyze the expression profiles of DEMs and DEGs in the nasal turbinate tissue at different time points after the newly emerged swine influenza A virus SW2783 cross-species infection with tree shrews, and miRNA-mRNA interaction maps were constructed and verified by RT-qPCR, miRNA transfection and luciferase reporter assay.

RESULTS

14 DEMs were screened based on functional analysis and interaction map, miR-760-3p, miR-449b-2, miR-30e-3p, and miR-429 were involved in the signal transduction process of replication and proliferation after infection, miR-324-3p, miR-1301-1, miR-103-1, miR-134-5p, miR-29a, miR-31, miR-16b, miR-34a, and miR-125b participate in negative feedback regulation of genes related to the immune function of the body to activate the antiviral immune response, and miR-106b-3p may be related to the cross-species infection potential of SW2783, and the expression level of these miRNAs varies in different days after infection.

CONCLUSIONS

The miRNA regulatory networks were constructed and 14 DEMs were identified, some of them can affect the replication and proliferation of viruses by regulating signal transduction, while others can play an antiviral role by regulating the immune response. It indicates that abnormal expression of miRNAs plays a crucial role in the regulation of cross-species IAVs infection, which lays a solid foundation for further exploration of the molecular regulatory mechanism of miRNAs in IAVs cross-species infection and anti-influenza virus targets.

Transcriptome profiling of bovine endometrial epithelial cells induced by lipopolysaccharides in vitro

Endometritis is an inflammation of the surface of the endometrium that does not penetrate the submucosa and can cause infertility and increase the elimination rate in cows. Endometrial epithelial cells are the first barrier of the endometrium against foreign stimuli and bacterial infection. Understanding the genetic changes in stimulated endometrial epithelial cells will help in the efforts to prevent and treat endometritis. This study investigated changes in bovine endometrial epithelial (BEEC) gene expression induced by lipopolysaccharide (LPS)-induced inflammation and compared transcriptome-wide gene changes between LPS- and phosphate-buffered saline (PBS)- treated BEECs by RNA sequencing. Compared with the PBS group, the LPS group showed 60 differentially expressed genes (DEGs) (36 upregulated, 24 downregulated). Gene Ontology enrichment analysis revealed that most enrichment occurred during CXCR chemokine receptor binding, inflammatory response, and neutrophil migration. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed DEGs mainly concentrated in cytokine-cytokine receptor interactions; IL-17, tumor necrosis factor, NOD-like receptor, chemokine, Toll-like receptor, and nuclear factor-κB signaling pathways; and the cytoplasmic DNA sensing pathway. Moreover, results revealed that cytokines SAA3 and HP increased significantly after LPS treatment. These effects of LPS on BEECs transcriptome and the molecular mechanism of endometritis provide a basis for improved clinical treatment and novel drug development.

Exploring potential therapeutic agents for lipopolysaccharide-induced septic cardiomyopathy based on transcriptomics using bioinformatics

Septic cardiomyopathy (SCM) is a common and severe complication of sepsis, characterized by left ventricular dilation and reduced ejection fraction leading to heart failure. The pathogenesis of SCM remains unclear. Understanding the SCM pathogenesis is essential in the search for effective therapeutic agents for SCM. This study was to investigate the pathophysiology of SCM and explore new therapeutic drugs by bioinformatics. An SCM rat model was established by injection of 10 mg/kg lipopolysaccharide (LPS) for 24 h, and the myocardial tissues were collected for RNA sequencing. The differentially expressed genes (DEGs) between LPS rats and control (Ctrl) with the thresholds of |log2fold change|≥ 1 and P < 0.05. A protein-protein interaction (PPI) network was constructed based on the DEGs. The hub genes were identified using five algorithms of Cytoscape in the PPI networks and validated in the GSE185754 dataset and by RT-qPCR. The hub genes were analyzed by Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG), as well as Gene set enrichment analyses (GSEA). In addition, the miRNAs of hub genes were predicted through miRWalk, and the candidate therapeutic drugs were identified using the Connectivity Map (CMAP) database. This study revealed the identified hub genes (Itgb1, Il1b, Rac2, Vegfa) and key miRNAs (rno-miR-541-5p, rno-miR-487b-3p, rno-miR-1224, rno-miR-378a-5p, rno-miR-6334, and rno-miR-466b-5p), which were potential biological targets and biomarkers of SCM. Anomalies in cytokine-cytokine receptor interactions, complement and coagulation cascades, chemokine signaling pathways, and MAPK signaling pathways also played vital roles in SCM pathogenesis. Two high-confidence candidate compounds (KU-0063794 and dasatinib) were identified from the CMAP database as new therapeutic drugs for SCM. In summary, these four identified hub genes and enrichment pathways may hold promise for diagnosing and treating SCM.

Autophagy and podocytopathy

Autophagy is a complex process of lysosomal-dependent degradation of unwanted cellular material. In response to endogenous or exogenous stimuli, autophagy is induced and regulated by two kinases: the AMP activated kinase and the mammalian target of rapamycin (mTOR). Cells activated by Unc-51-like kinase 1 form a double membrane complex that sequesters the cargo (phagophore) and elongates producing spherical vesicles (autophagosomes). These reach and fuse with lysosomes, which degrade the cargo (autolysosomes). The resulting macromolecules are released back and recycled in the cytosol for reuse. In the podocyte, autophagy is a homeostatic mechanism that contributes to the formation and preservation of the morphological and functional integrity of actin cytoskeleton. Podocytes, fenestrated endothelial cells and glomerular basement membrane compose the glomerular filtration barrier. Podocyte damage may cause dysfunction of the glomerular barrier, proteinuria and glomerulosclerosis in different glomerular diseases and particularly in so-called podocytopathies, namely minimal change disease and focal segmental glomerulosclerosis. Several drugs and molecules may activate autophagic function in murine models. Among them, aldosterone inhibitors, mineralocorticoid inhibitors and vitamin D3 were proven to protect podocyte from injury and reduce proteinuria in clinical studies. However, no clinical trial with autophagy regulators in podocytopathies has been conducted. Caution is needed with other autophagy activators, such as mTOR inhibitors and metformin, because of potential adverse events.

Emerging roles of macrophages in heart failure and associated treatment approaches

Heart failure is typically caused by different cardiovascular conditions and has a poor prognosis. Despite the advances in treatment in recent decades, heart failure has remained a major cause of morbidity and mortality worldwide. As revealed by in vivo and in vitro experiments, inflammation plays a crucial role in adverse cardiac remodeling, ultimately leading to heart failure. Macrophages are central to the innate immune system, and they are the most indispensable cell type for all cardiac injuries and remodeling stages. The immediate microenvironment regulates their polarization and secretion. In this review, we summarize the phenotypic heterogeneity and governing roles of macrophages in the infarcted, inflamed, and aging heart and assess their significance as potential therapeutic targets in heart failure. We also highlight the current missing links and major challenges in the field that remain to be addressed before macrophages can be exploited for therapeutic applications.

Autophagy and SARS-CoV-2-Old Players in New Games

At present it is well-defined that autophagy is a fundamental process essential for cell life but its pro-viral and anti-viral role has been stated out with the COVID pandemic. However, viruses in turn have evolved diverse adaptive strategies to cope with autophagy driven host defense, either by blocking or hijacking the autophagy machinery for their own benefit. The mechanisms underlying autophagy modulation are presented in the current review which summarizes the accumulated knowledge on the crosstalk between autophagy and viral infections, with a particular emphasizes on SARS-CoV-2. The different types of autophagy related to infections and their molecular mechanisms are focused in the context of inflammation. In particular, SARS-CoV-2 entry, replication and disease pathogenesis are discussed. Models to study autophagy and to formulate novel treatment approaches and pharmacological modulation to fight COVID-19 are debated. The SARS-CoV-2-autophagy interplay is presented, revealing the complex dynamics and the molecular machinery of autophagy. The new molecular targets and strategies to treat COVID-19 effectively are envisaged. In conclusion, our finding underline the importance of development new treatment strategies and pharmacological modulation of autophagy to fight COVID-19.

Autophagy in Inflammatory Response against SARS-CoV-2

The coronavirus disease pandemic, which profoundly reshaped the world in 2019 (COVID-19), and is currently ongoing, has affected over 200 countries, caused over 500 million cumulative cases, and claimed the lives of over 6.4 million people worldwide as of August 2022. The causative agent is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Depicting this virus' life cycle and pathogenic mechanisms, as well as the cellular host factors and pathways involved during infection, has great relevance for the development of therapeutic strategies. Autophagy is a catabolic process that sequesters damaged cell organelles, proteins, and external invading microbes, and delivers them to the lysosomes for degradation. Autophagy would be involved in the entry, endo, and release, as well as the transcription and translation, of the viral particles in the host cell. Secretory autophagy would also be involved in developing the thrombotic immune-inflammatory syndrome seen in a significant number of COVID-19 patients that can lead to severe illness and even death. This review aims to review the main aspects that characterize the complex and not yet fully elucidated relationship between SARS-CoV-2 infection and autophagy. It briefly describes the key concepts regarding autophagy and mentions its pro- and antiviral roles, while also noting the reciprocal effect of viral infection in autophagic pathways and their clinical aspects.

Interactions of Autophagy and the Immune System in Health and Diseases

Autophagy is a highly conserved process that utilizes lysosomes to selectively degrade a variety of intracellular cargo, thus providing quality control over cellular components and maintaining cellular regulatory functions. Autophagy is triggered by multiple stimuli ranging from nutrient starvation to microbial infection. Autophagy extensively shapes and modulates the inflammatory response, the concerted action of immune cells, and secreted mediators aimed to eradicate a microbial infection or to heal sterile tissue damage. Here, we first review how autophagy affects innate immune signaling, cell-autonomous immune defense, and adaptive immunity. Then, we discuss the role of non-canonical autophagy in microbial infections and inflammation. Finally, we review how crosstalk between autophagy and inflammation influences infectious, metabolic, and autoimmune disorders.

Autophagy in SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) orchestrates host factors to remodel endomembrane compartments for various steps of the infection cycle. SARS-CoV-2 also intimately intersects with the catabolic autophagy pathway during infection. In response to virus infection, autophagy acts as an innate defensive system by delivering viral components/particles to lysosomes for degradation. Autophagy also elicits antiviral immune responses. SARS-CoV-2, like other positive-stranded RNA viruses, has evolved various mechanisms to escape autophagic destruction and to hijack the autophagic machinery for its own benefit. In this review, we will focus on how the interplay between SARS-CoV-2 viral proteins and autophagy promotes viral replication and transmission. We will also discuss the pathogenic effects of SARS-CoV-2-elicited autophagy dysregulation and pharmacological interventions targeting autophagy for COVID-19 treatment.

Autophagy in lupus nephritis: A delicate balance between regulation and disease

Autophagy is a highly regulated process wherein an unwanted cargo of damaged and dysfunctional cytoplasmic components is removed, delivered to lysosomes for degradation, and released back into the cytoplasm. Accumulating evidence suggests an important role of autophagy in the pathophysiology of systemic lupus erythematosus, with profound effects on both innate and adaptive immunity. Autophagy downregulation results in the inhibition of antigen presenting cells, reduced release of neutrophil extracellular traps and decreased activation of effector T and B cells, leading to reduced autoantibody production and attenuated type 1 interferon signaling. However, defective autophagy may accelerate the production of other inflammatory cytokines and reduce the clearance of apoptotic cells, promoting lupus development. In addition, autophagy dysfunction can concur to the pathogenesis of kidney injury in lupus nephritis. Autophagy is a pivotal mechanism to maintain podocyte integrity and endothelial cell survival. Several animal models have demonstrated that defective autophagy leads to podocyte injury and can promote an endothelial pro-inflammatory and atherogenic phenotype. Moreover, autophagy is a key homeostatic regulator of renal tubular cells, and recent evidence has pointed out that chronic autophagy deficiency may accelerate kidney fibrosis. Targeting autophagy may theoretically improve lupus nephritis outcomes, but novel, non-invasive methods to measure and monitor autophagic activity are urgently needed. In addition, the extent and timing of autophagy inhibition still require additional studies before clinical translation may be attempted. In this review, we will also discuss the effect of several clinically available drugs that can regulate the autophagic flux and their effect in lupus nephritis patients.

Autophagy Modulators in Coronavirus Diseases: A Double Strike in Viral Burden and Inflammation

Coronaviruses are the etiologic agents of several diseases. Coronaviruses of critical medical importance are characterized by highly inflammatory pathophysiology, involving severe pulmonary impairment and infection of multiple cell types within the body. Here, we discuss the interplay between coronaviruses and autophagy regarding virus life cycle, cell resistance, and inflammation, highlighting distinct mechanisms by which autophagy restrains inflammatory responses, especially those involved in coronavirus pathogenesis. We also address different autophagy modulators available and the rationale for drug repurposing as an attractive adjunctive therapy. We focused on pharmaceuticals being tested in clinical trials with distinct mechanisms but with autophagy as a common target. These autophagy modulators act in cell resistance to virus infection and immunomodulation, providing a double-strike to prevent or treat severe disease development and death from coronaviruses diseases.

Regulation of antiviral immune response by African swine fever virus (ASFV)

African swine fever (ASF) is a highly contagious and acute hemorrhagic viral disease with a high mortality approaching 100% in domestic pigs. ASF is an endemic in countries in sub-Saharan Africa. Now, it has been spreading to many countries, especially in Asia and Europe. Due to the fact that there is no commercial vaccine available for ASF to provide sustainable prevention, the disease has spread rapidly worldwide and caused great economic losses in swine industry. The knowledge gap of ASF virus (ASFV) pathogenesis and immune evasion is the main factor to limit the development of safe and effective ASF vaccines. Here, we will summarize the molecular mechanisms of how ASFV interferes with the host innate and adaptive immune responses. An in-depth understanding of ASFV immune evasion strategies will provide us with rational design of ASF vaccines.

Altruism and Phenoptosis as Programs Supported by Evolution

Phenoptosis is a programmed death that has emerged in the process of evolution, sometimes taking the form of an altruistic program. In particular, it is believed to be a weapon against the spread of pandemics in the past and an obstacle in fighting pandemics in the present (COVID). However, on the evolutionary scale, deterministic death is not associated with random relationships (for example, bacteria with a particular mutation), but is a product of higher nervous activity or a consequence of established hierarchy that reaches its maximal expression in eusocial communities of Hymenoptera and highly social communities of mammals. Unlike a simple association of individuals, eusociality is characterized by the appearance of non-reproductive individuals as the highest form of altruism. In contrast to primitive programs for unicellular organisms, higher multicellular organisms are characterized by the development of behavior-based phenoptotic programs, especially in the case of reproduction-associated limitation of lifespan. Therefore, we can say that the development of altruism in the course of evolution of sociality leads in its extreme manifestation to phenoptosis. Development of mathematical models for the emergence of altruism and programmed death contributes to our understanding of mechanisms underlying these paradoxical counterproductive (harmful) programs. In theory, this model can be applied not only to insects, but also to other social animals and even to the human society. Adaptive death is an extreme form of altruism. We consider altruism and programmed death as programmed processes in the mechanistic and adaptive sense, respectively. Mechanistically, this is a program existing as a predetermined chain of certain responses, regardless of its adaptive value. As to its adaptive value (regardless of the degree of "phenoptoticity"), this is a characteristic of organisms that demonstrate high levels of kinship, social organization, and physical association typical for higher-order individuals, e.g., unicellular organisms forming colonies with some characteristics of multicellular animals or colonies of multicellular animals displaying features of supraorganisms.

Benzyl-para-di-[5-methyl-4-(n-octylamino) pyrimidin-2(1H)one] as an interferon beta (IFN-β) modulator

IFN-β is a cytokine that plays a significant role in the immune system. Inhibition of IFN-β might be used as a therapeutic approach to treat septic shock. A peptidomimetic previously developed by our research team, 1-benzyl-5-methyl-4-(n-octylamino)pyrimidin-2(1H)-one (LT87), was used as an cardioprotective agent in a myocardial ischemia (MI) mouse model. We have developed new LT87 derivatives by synthetizing its dimers in an attempt to extend its structural variety and enhance its biological activity. A dimeric derivative, LT127, exhibited a dose-dependent inhibition of LPS-mediated IFN-β and subsequent CXCL10 mRNA transcription. The effect was selective and transduced through TLR4- and TRAM/TRIF-mediated signaling, with no significant effect on MyD88-dependent signaling. However, this effect was not specific to TLR4, since a similar effect was observed both on TLR8- and MDA5/RIG-I-stimulated IFN-β expression. Nevertheless, LT127 might serve as a drug candidate, specifically as an inhibitor for IFN-β production in order to develop a novel therapeutic approach to prevent septic shock.

Palmitic acid up regulates Gal-3 and induces insulin resistance in macrophages by mediating the balance between KLF4 and NF-κB

Insulin resistance is the main sign of type 2 diabetes mellitus and is often accompanied by the infiltration of inflammatory factors. These inflammatory factors are mainly produced and secreted by macrophages. The purpose of the current study was to explore the relationship between macrophages and insulin resistance, and to determine its underlying mechanism. The insulin resistance of macrophages was induced by palmitic acid (PA) in vitro. The glucose uptake rate of macrophages, the expression levels of inflammatory cytokines and the expression levels of insulin resistance-related proteins were detected. The protein expression levels of Krüppel-like factor 4 (KLF4), toll-like receptor 4 (TLR4), NF-κB and Galectin-3 (Gal-3) were detected via western blotting and recovery experiments were performed by combining the Gal-3 and TLR4 inhibitors GB1107 and TAK242. The results revealed that PA-induced macrophages demonstrated insulin resistance. Additionally, KLF4 protein was inhibited and the sugar uptake rate was significantly lower than that of the control group. Western blotting and immunofluorescence assays revealed that the expression of Gal-3 in PA-induced macrophages was significantly upregulated. The addition of the Gal-3 inhibitor GB1107 significantly increased glucose utilization and reduced insulin resistance in PA-treated cells. Inhibitor of TLR4 inhibited the protein expression level of the TLR4/NF-κB pathway. In conclusion, PA promoted the TLR4/phosphorylated-NF-κB signaling pathway by inhibiting KLF4, promoted the upregulation of Gal-3 expression and improved the insulin resistance of macrophages.

Problems of Pathogenesis and Pathogenetic Therapy of COVID-19 from the Perspective of the General Theory of Pathological Systems (General Pathological Processes)

The COVID-19 pandemic examines not only the state of actual health care but also the state of fundamental medicine in various countries. Pro-inflammatory processes extend far beyond the classical concepts of inflammation. They manifest themselves in a variety of ways, beginning with extreme physiology, then allostasis at low-grade inflammation, and finally the shockogenic phenomenon of "inflammatory systemic microcirculation". The pathogenetic core of critical situations, including COVID-19, is this phenomenon. Microcirculatory abnormalities, on the other hand, lie at the heart of a specific type of general pathological process known as systemic inflammation (SI). Systemic inflammatory response, cytokine release, cytokine storm, and thrombo-inflammatory syndrome are all terms that refer to different aspects of SI. As a result, the metabolic syndrome model does not adequately reflect the pathophysiology of persistent low-grade systemic inflammation (ChSLGI). Diseases associated with ChSLGI, on the other hand, are risk factors for a severe COVID-19 course. The review examines the role of hypoxia, metabolic dysfunction, scavenger receptors, and pattern-recognition receptors, as well as the processes of the hemophagocytic syndrome, in the systemic alteration and development of SI in COVID-19.

Methionine enkephalin activates autophagy and stimulates tumour cell immunogenicity in human cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (CSCC) is a common skin tumour. Due to weak immunogenicity, recurrence is frequent after treatment. In this study, we explored the effects and mechanisms of methionine enkephalin (MENK), an endogenous opioid peptide and negative growth regulator, in CSCC. MENK inhibited A431 cell proliferation and promoted apoptosis through the opioid growth factor receptor (OGFr). Importantly, MENK also induced autophagy in CSCC and stimulated the emission of DAMPs in A431 cells, which resulted in enhanced activation of dendritic cells (DC).In conclusion, MENK provides an effective method with therapeutic potential to modulate the CSCC microenvironment by utilizing autophagy in the cancer cells.

Agomelatine Softens Depressive-Like Behavior through the Regulation of Autophagy and Apoptosis

Depression is a common and disabling mental disorder with high recurrence rate. Searching for more effective treatments for depression is a long-standing primary objective in neuroscience. Agomelatine (AGO) was reported as an antidepressant with unique pharmacological effects. However, its effects and the underlying mechanism are still unclear. In this study, we sought to evaluate the antidepressant effects of AGO on the chronic restraint stress (CRS) mouse model and preliminarily investigate its effects on the gut microbial metabolites. The CRS model mice were established in 28 days with AGO (60 mg/kg/day, by oral) or fluoxetine (15 mg/kg/day, by oral) administration. The number of behavioral tests was conducted to evaluate the effect of AGO on depression-like behavior alleviation. Meanwhile, the expression of the BDNF/TrkB/pERK signaling pathway, apoptosis, autophagy, and inflammatory protein markers were assessed using western blot and immunofluorescence. Our findings show that AGO can attenuate the depressive-like behavior that significantly appeared in both sucrose preference and forced swimming tests. Additionally, a noticeable upregulation of autophagy including Beclin1 and LC3II, microglial activity marker Iba-1, and BDNF/TrkB/pERK signaling pathways are indicated. An obvious decreased expression of NF-κB, iNOS, and nNOS as well as apoptosis including Bax is observed in AGO administration mice. On the other hand, we found that AGO impacted the rebalancing of short-chain fatty acids (SCFAs) in mouse feces. Altogether, these findings suggest that AGO can exert antidepressant effects in a different molecular mechanism.

STING, a promising target for small molecular immune modulator: A review

Stimulator of interferon genes (STING) plays a crucial role in human innate immune system, which is gradually concerned following the emerging immunotherapy. Activated STING induces the production of type I interferons (IFNs) and proinflammatory cytokines through STING-TBK1-IRF3/NF-κB pathway, which could be applied into the treatment of infection, inflammation, and tumorigenesis. Here, we provided a detailed summary of STING from its structure, function and regulation. Especially, we illustrated the canonical or noncanonical cyclic dinucleotides (CDNs) and synthetic small molecules for STING activation or inhibition and their efficacy in related diseases. Importantly, we particularly emphasized the discovery, development and modification of STING agonist or antagonist, attempting to enlighten reader's mind for enriching small molecular modulator of STING. In addition, we summarized biological evaluation methods for the assessment of small molecules activity.

TLR7/8 in the Pathogenesis of Parkinson's Disease

Neuroinflammation and autoimmune mechanisms have a key part in the pathogenesis of Parkinson’s disease (PD). Therefore, we evaluated the role of Toll-like receptors (TLRs) as a link between inflammation and autoimmunity in PD. An in vivo model of PD was performed by administration of 1-metil 4-fenil 1,2,3,6-tetraidro-piridina (MPTP) at the dose of 20 mg/kg every 2 h for a total administration of 80/kg, both in single Knock Out (KO) mice for TLR7, TLR 8, and TLR9 and in double KO mice for TLR 7/8^-/-. All animals were compared with WT animals used as a control group. All animals were sacrificed after 7 days form the first administration of MPTP. The genetic absence of TLR 7 and 8 modified the PD pathway, increasing the immunoreactivity for TH and DAT compared to PD groups and decreasing microglia and astrocytes activation. Moreover, the deletion of TLR7 and TLR8 significantly reduced T-cell infiltration in the substantia nigra and lymph nodes, suggesting a reduction of T-cell activation. Therefore, our result highlights a possibility that an immunotherapy approach, by using a dual antagonist of TLR 7 and 8, could be considered as a possible target to develop new therapies for Parkinson diseases.

Glycyrrhizin potentially suppresses the inflammatory response in preeclampsia rat model

OBJECTIVE

The expression of high-mobility group box 1 (HMGB1) in trophoblasts is elevated, which contributes to the development of preeclampsia. Thus, this study aimed to investigate the effect of glycyrrhizin, a natural HMGB1 inhibitor, on the development of preeclampsia.

METHODS

Preeclampsia was induced in pregnant Lewis rats through oral administration of L-NAME (50 mg/kg/day) on gestational day (GD) 13-19. Glycyrrhizin (10, 30, or 60 mg/kg/day) was given by oral gavage on GD 10-19. Systolic blood pressure (SBP), diastolic blood pressure (DBP), 24-hour proteinuria, live pup birth ratio, pup weight, pup body length, and placental weight were measured. Also, the expression levels of inflammatory factors (TNF-α, iNOS, IL-1, and IL-6), HMGB1, and TLR4 in the placenta or in the serum were analyzed by enzyme-linked immunosorbent assay, RT-PCR, and Western blot analysis.

RESULTS

Glycyrrhizin significantly reduced the SBP, DBP, and 24-hour proteinuria on GD 16 and 20 in a dose-dependent manner and ameliorated the pregnancy outcomes in preeclampsia rats. The elevated inflammatory molecule levels were markedly decreased by glycyrrhizin not only in the serum but also in the placenta. Moreover, the upregulated HMGB1 and TLR4 expression levels were diminished by glycyrrhizin administration.

CONCLUSION

This study shows that glycyrrhizin could alleviate preeclampsia and the preeclampsia-associated inflammatory reaction, and this effect could be attributed to HMGB1 inhibition.

Beclin1 Haploinsufficiency accentuates second-hand smoke exposure -induced myocardial Remodeling and contractile dysfunction through a STING-mediated mechanism

Second-hand smoking evokes inflammation and cardiovascular diseases. Recent evidence has revealed a pivotal role for deranged autophagy in smoke exposure-induced cardiac anomalies. This study evaluated the impact of haploinsufficiency of the mTOR-independent autophagy protein Beclin1 on side-stream smoke exposure-induced cardiac anomalies and mechanism(s) involved. Adult WT and Beclin1 haploinsufficiency (Becn^+/-) mice were exposed to cigarette smoke for 1 h daily for 90 days. Echocardiographic, cardiomyocyte function, intracellular Ca²⁺, autophagy, mitophagy, apoptosis and inflammation were examined. DHE staining was employed to evaluate O₂^- level. Our data revealed that Beclin1 deficiency exacerbated smoke exposure-induced myocardial anomalies in geometry, fractional shortening, cardiomyocyte function, intracellular Ca²⁺ handling, TEM ultrastructure, and inflammation along with pronounced apoptosis and O₂^- production. Side-stream smoke provoked excessive autophagy/mitophagy, mtDNA release, and activation of innate immune response signals cyclic GMP-AMP synthase (cGAS) and its effector - stimulator of interferon genes (STING), the effect was abolished or unaffected by Becn haploinsufficiency. STING phosphorylation was overtly promoted by smoke exposure in Becn^+/- mice. Smoke exposure also suppressed phosphorylation of mTOR although it facilitated that of ULK1 in both groups. In vitro data revealed that inhibition of cGAS or STING failed to affect smoke extract-induced mitophagy although they abrogated smoke extract-induced cardiomyocyte dysfunction except cGAS inhibition in Becn^+/- mice. These data suggest that Beclin1 is integral in the maintenance of cardiac homeostasis under side-stream smoke exposure via a STING-mediated mechanism.

Double knockout of Akt2 and AMPK accentuates high fat diet-induced cardiac anomalies through a cGAS-STING-mediated mechanism

High fat diet intake contributes to undesired cardiac geometric and functional changes although the underlying mechanism remains elusive. Akt and AMPK govern to cardiac homeostasis. This study examined the impact of deletion of Akt2 (main cardiac isoform of Akt) and AMPKα2 on high fat diet intake-induced cardiac remodeling and contractile anomalies and mechanisms involved. Cardiac geometry, contractile, and intracellular Ca²⁺ properties were evaluated using echocardiography, IonOptix® edge-detection and fura-2 techniques in wild-type (WT) and Akt2-AMPK double knockout (DKO) mice receiving low fat (LF) or high fat (HF) diet for 4 months. Our results revealed that fat diet intake elicit obesity, cardiac remodeling (hypertrophy, LV mass, LVESD, and cross-sectional area), contractile dysfunction (fractional shortening, peak shortening, maximal velocity of shortening/relengthening, time-to-90% relengthening, and intracellular Ca²⁺ handling), ultrastructural disarray, apoptosis, O₂^-, inflammation, dampened autophagy and mitophagy. Although DKO did not affect these parameters, it accentuated high fat diet-induced cardiac remodeling and contractile anomalies. High fat intake upregulated levels of cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING), and STING phosphorylation while suppressing phosphorylation of ULK1 (Ser⁷⁵⁷ and Ser⁷⁷⁷), with a more pronounced effect in DKO mice. In vitro data revealed that inhibition of cGAS and STING using PF-06928215 and Astin C negated palmitic acid-induced cardiomyocyte contractile dysfunction. Biological function analysis for all differentially expressed genes (DEGs) depicted that gene ontology terms associated with Akt and AMPK signaling processes were notably changed in high fat-fed hearts. Our data indicate that Akt2-AMPK ablation accentuated high fat diet-induced cardiac anomalies possibly through a cGAS-STING-mechanism.

Digesting the crisis: autophagy and coronaviruses

Autophagy is a catabolic pathway with multifaceted roles in cellular homeostasis. This process is also involved in the antiviral response at multiple levels, including the direct elimination of intruding viruses (virophagy), the presentation of viral antigens, the fitness of immune cells, and the inhibition of excessive inflammatory reactions. In line with its central role in immunity, viruses have evolved mechanisms to interfere with or to evade the autophagic process, and in some cases, even to harness autophagy or constituents of the autophagic machinery for their replication. Given the devastating consequences of the current COVID-19 pandemic, the question arises whether manipulating autophagy might be an expedient approach to fight the novel coronavirus SARS-CoV-2. In this piece, we provide a short overview of the evidence linking autophagy to coronaviruses and discuss whether such links may provide actionable targets for therapeutic interventions.

Transcriptomic Changes Related to Cellular Processes with Particular Emphasis on Cell Activation in Lysosomal Storage Diseases from the Group of Mucopolysaccharidoses

Although mucopolysaccharidoses (MPS), inherited metabolic diseases from the group of lysosomal storage diseases (LSD), are monogenic disorders, recent studies indicated that their molecular mechanisms are complicated. Storage of glycosaminoglycans (GAGs), arising from a deficiency in one of the enzymes involved in the degradation of these compounds, is the primary cause of each MPS type. However, dysfunctions of various cellular organelles and disturbance of cellular processes have been reported which contribute considerably to pathomechanisms of the disease. Here, we present a complex transcriptomic analysis in which all types and subtypes of MPS were investigated, with special emphasis on genes related to cell activation processes. Complex changes in expression of these genes were found in fibroblasts of all MPS types, with number of transcripts revealing higher or lower levels (relative to control fibroblasts) between 19 and over 50, depending on MPS type. Genes in which expression was significantly affected in most MPS types code for proteins involved in following processes, classified according to Gene Ontology knowledge database: cell activation, cell growth, cell recognition, and cell division. Levels of some transcripts (including CD9, CLU, MME and others) were especially significantly changed (over five times relative to controls). Our results are discussed in the light of molecular pathomechanisms of MPS, indicating that secondary and/or tertiary changes, relative to GAG storage, might significantly modulate cellular dysfunctions and contribute to molecular mechanisms of the disease. This may influence the efficacy of various therapies and suggests why various treatments are not fully effective in improving the complex symptoms of MPS.