Belimumab Decreases Autophagy and Citrullination in Peripheral Blood Mononuclear Cells from Patients with Systemic Lupus Erythematosus

Is Autophagy a Friend or Foe in SARS-CoV-2 Infection?

As obligate parasites, viruses need to hijack resources from infected cells to complete their lifecycle. The interaction between the virus and host determines the viral infection process, including viral propagation and the disease's outcome. Understanding the interaction between the virus and host factors is a basis for unraveling the intricate biological processes in the infected cells and thereby developing more efficient and targeted antivirals. Among the various fundamental virus-host interactions, autophagy plays vital and also complicated roles by directly engaging in the viral lifecycle and functioning as an anti- and/or pro-viral factor. Autophagy thus becomes a promising target against virus infection. Since the COVID-19 pandemic, there has been an accumulation of studies aiming to investigate the roles of autophagy in SARS-CoV-2 infection by using different models and from distinct angles, providing valuable information for systematically and comprehensively dissecting the interplay between autophagy and SARS-CoV-2. In this review, we summarize the advancements in the studies of the interaction between SARS-CoV-2 and autophagy, as well as detailed molecular mechanisms. We also update the current knowledge on the pharmacological strategies used to suppress SARS-CoV-2 replication through remodeling autophagy. These extensive studies on SARS-CoV-2 and autophagy can advance our understanding of virus-autophagy interaction and provide insights into developing efficient antiviral therapeutics by regulating autophagy.

The multifaceted role of autophagy in skin autoimmune disorders: a guardian or culprit?

Autophagy is a cellular process that functions to maintain intracellular homeostasis via the degradation and recycling of defective organelles or damaged proteins. This dynamic mechanism participates in various biological processes, such as the regulation of cellular differentiation, proliferation, survival, and the modulation of inflammation and immune responses. Recent evidence has demonstrated the involvement of polymorphisms in autophagy-related genes in various skin autoimmune diseases. In addition, autophagy, along with autophagy-related proteins, also contributes to homeostasis maintenance and immune regulation in the skin, which is associated with skin autoimmune disorders. This review aims to provide an overview of the multifaceted role of autophagy in skin autoimmune diseases and shed light on the potential of autophagy-targeting therapeutic strategies in dermatology.

Natural isoaspartyl protein modification of ZAP70 alters T cell responses in lupus

Protein posttranslational modifications (PTMs) arise in a number of normal cellular biological pathways and in response to pathology caused by inflammation and/or infection. Indeed, a number of PTMs have been identified and linked to specific autoimmune responses and metabolic pathways. One particular PTM, termed isoaspartyl (isoAsp or isoD) modification, is among the most common spontaneous PTM occurring at physiological pH and temperature. Herein, we demonstrate that isoAsp modifications arise within the ZAP70 protein tyrosine kinase upon T-cell antigen receptor (TCR) engagement. The enzyme protein L-isoaspartate O-methyltransferase (PCMT1, or PIMT, EC 2.1.1.77) evolved to repair isoaspartyl modifications in cells. In this regard, we observe that increased levels of isoAsp modification that arise under oxidative stress are correlated with reduced PIMT activity in patients with systemic lupus erythematosus (SLE). PIMT deficiency leads to T cell hyper-proliferation and hyper-phosphorylation through ZAP70 signaling. We demonstrate that inducing the overexpression of PIMT can correct the hyper-responsive phenotype in lupus T cells. Our studies reveal a phenotypic role of isoAsp modification and phosphorylation of ZAP70 in lupus T cell autoimmunity and provide a potential therapeutic target through the repair of isoAsp modification.

The Extracellular Vesicle Citrullinome and Signature in a Piglet Model of Neonatal Seizures

Neonatal seizures are commonly associated with acute perinatal brain injury, while understanding regarding the downstream molecular pathways related to seizures remains unclear. Furthermore, effective treatment and reliable biomarkers are still lacking. Post-translational modifications can contribute to changes in protein function, and post-translational citrullination, which is caused by modification of arginine to citrulline via the calcium-mediated activation of the peptidylarginine deiminase (PAD) enzyme family, is being increasingly linked to neurological injury. Extracellular vesicles (EVs) are lipid-bilayer structures released from cells; they can be isolated from most body fluids and act as potential liquid biomarkers for disease conditions and response to treatment. As EVs carry a range of genetic and protein cargo that can be characteristic of pathological processes, the current study assessed modified citrullinated protein cargo in EVs isolated from plasma and CSF in a piglet neonatal seizure model, also following phenobarbitone treatment. Our findings provide novel insights into roles for PAD-mediated changes on EV signatures in neonatal seizures and highlight the potential of plasma- and CSF-EVs to monitor responses to treatment.

[Berberine inhibits autophagy and promotes apoptosis of fibroblast-like synovial cells from rheumatoid arthritis patients through the ROS/mTOR signaling pathway]

OBJECTIVE

To evaluate the regulatory effect of berberine on autophagy and apoptosis balance of fibroblast-like synoviocytes (FLSs) from patients with in rheumatoid arthritis (RA) and explore the mechanism.

METHODS

The inhibitory effect of 10, 20, 30, 40, 50, 60, 70, and 80 μmol/L berberine on RA-FLS proliferation was assessed using CCK-8 method. Annexin V/PI and JC-1 immunofluorescence staining was used to analyze the effect of berberine (30 μmol/L) on apoptosis of 25 ng/mL TNF-α- induced RA-FLSs, and Western blotting was performed to detect the changes in the expression levels of autophagy- and apoptosis-related proteins. The cells were further treated with the autophagy inducer RAPA and the autophagy inhibitor chloroquine to observe the changes in autophagic flow by laser confocal detection of mCherry-EGFP-LC3B. RA-FLSs were treated with the reactive oxygen species (ROS) mimic H2O2 or the ROS inhibitor NAC, and the effects of berberine on ROS, mTOR and p-mTOR levels were observed.

RESULTS

The results of CCK-8 assay showed that berberine significantly inhibited the proliferation of RA-FLSs in a time- and concentration-dependent manner. Flow cytometry and JC-1 staining showed that berberine (30 μmol/L) significantly increased apoptosis rate (P < 0.01) and reduced the mitochondrial membrane potential of RA-FLSs (P < 0.05). Berberine treatment obviously decreased the ratios of Bcl-2/Bax (P < 0.05) and LC3B-II/I (P < 0.01) and increased the expression of p62 protein in the cells (P < 0.05). Detection of mCherry-EGFP-LC3B autophagy flow revealed obvious autophagy flow block in berberine-treated RA-FLSs. Berberine significantly reduced the level of ROS in TNF-α-induced RA-FLSs and upregulated the expression level of autophagy-related protein p-mTOR (P < 0.01); this effect was regulated by ROS level, and the combined use of RAPA significantly reduced the pro-apoptotic effect of berberine in RA-FLSs (P < 0.01).

CONCLUSION

Berberine can inhibit autophagy and promote apoptosis of RA-FLSs by regulating the ROS-mTOR pathway.

Selective inhibition of peptidyl-arginine deiminase (PAD): can it control multiple inflammatory disorders as a promising therapeutic strategy?

Peptidyl arginine deiminases (PADs) are a family of post-translational modification enzymes that irreversibly citrullinate (deiminate) arginine residues of protein and convert them to a non-classical amino acid citrulline in the presence of calcium ions. It has five isotypes, such as PAD1, PAD2, PAD3, PAD4, and PAD6, found in mammalian species. It has been suggested that increased PAD expression in various tissues contributes to the development of multiple inflammatory diseases, including rheumatoid arthritis (RA), cancer, diabetes, and neurological disorders. Elevation of PAD enzyme expression depends on several factors like rising intracellular Ca²⁺ levels, oxidative stress, and proinflammatory cytokines. PAD inhibitors originating from natural or synthetic sources can be used as a novel therapeutic approach concerning inflammatory disorders. Here, we review the pathological role of PAD in several inflammatory disorders, factors that trigger PAD expression, epigenetic role and finally, decipher the therapeutic approach of PAD inhibitors in multiple inflammatory disorders.

An artificial neural network model based on autophagy-related genes in childhood systemic lupus erythematosus

Background

Childhood systemic lupus erythematosus (cSLE) is a multisystemic, life-threatening autoimmune disease. Compared to adults, SLE in childhood is more active, can cause multisystem involvement including renal, neurological and hematological, and can cause cumulative damage across systems more rapidly. Autophagy, one of the core functions of cells, is involved in almost every process of the immune response and has been shown to be associated with many autoimmune diseases, being a key factor in the interplay between innate and adaptive immunity. Autophagy influences the onset, progression and severity of SLE. This paper identifies new biomarkers for the diagnosis and treatment of childhood SLE based on an artificial neural network of autophagy-related genes.

Methods

We downloaded dataset GSE100163 from the Gene Expression Omnibus database and used Protein–protein Interaction Network (PPI) and Least Absolute Shrinkage and Selection Operator (LASSO) to screen the signature genes of autophagy-related genes in cSLE. A new artificial neural network model for cSLE diagnosis was constructed using the signature genes. The predictive efficiency of the model was also validated using the dataset GSE65391. Finally, "CIBERSORT" was used to calculate the infiltration of immune cells in cSLE and to analyze the relationship between the signature genes and the infiltration of immune cells.

Results

We identified 37 autophagy-related genes that differed in cSLE and normal samples, and finally obtained the seven most relevant signature genes for cSLE (DDIT3, GNB2L1, CTSD, HSPA8, ULK1, DNAJB1, CANX) by PPI and LASOO regression screening, and constructed an artificial neural network diagnostic model for cSLE. Using this model, we plotted the ROC curves for the training and validation group diagnoses with the area under the curve of 0.976 and 0.783, respectively. Finally, we performed immunoassays on cSLE samples, and the results showed that Plasma cells, Macrophages M0, Dendritic cells activated and Neutrophils were significantly infiltrated in cSLE.

Conclusion

We constructed an artificial neural network diagnostic model of seven autophagy-related genes that can be used for the diagnosis of cSLE. Meanwhile, the characteristic genes affect the immune infiltration of cSLE, which may provide new perspectives for the exploration of cSLE treatment and related mechanisms.

Lymphocytes are less sensitive to autophagy than monocytes during fasting and exercise conditions

The concomitant investigation of apoptosis (a regulated cell death) and autophagy (a conserved cell survival mechanism) in immune cells is rare. More detailed knowledge of these two types of self-consumption in circulating lymphocytes and monocytes would be important, since conditions such as fasting and acute exercise could promote health by a coordinated/linked modulation of autophagy and apoptosis in these mononuclear cells. In this study we performed flow cytometry to quantify numbers of apoptotic and autophagic mononuclear cells, lymphocytes and monocytes in fasting, standardized fed, and exercise conditions, using Annexin V, LC3B, and p62, respectively. We show that within total mononuclear cells lymphocytes are less apoptotic and autophagic than monocytes during fasting (p < 0.001, p < 0.05, respectively) and after acute exercise (p < 0.01, p < 0.05, respectively). Fasting increased circulating autophagic monocyte concentrations, but not lymphocytes compared to the fed control condition. Acute exercise elevated circulating autophagic lymphocyte concentrations, but not monocytes. Interestingly, Western blotting analysis of the fasting samples showed that higher LC3BII/I ratios were correlated with lower numbers of autophagic mononuclear cells (r = − 0.74, p = 0.02, n = 8), which could be attributed to the monocyte subgroup, but not lymphocytes. These results extend the current knowledge of the two types of self-consumption in circulating immune cells and underline their possible importance in pro-inflammatory monocytes during fasting and exercise as health promoting interventions.

Autophagy in Rheumatic Diseases: Role in the Pathogenesis and Therapeutic Approaches

Autophagy is a lysosomal pathway for the degradation of damaged proteins and intracellular components that promotes cell survival under specific conditions. Apoptosis is, in contrast, a critical programmed cell death mechanism, and the relationship between these two processes influences cell fate. Recent evidence suggests that autophagy and apoptosis are involved in the self-tolerance promotion and in the regulatory mechanisms contributing to disease susceptibility and immune regulation in rheumatic diseases. The aim of this review is to discuss how the balance between autophagy and apoptosis may be dysregulated in multiple rheumatic diseases and to dissect the role of autophagy in the pathogenesis of rheumatoid arthritis, systemic lupus erythematosus, and Sjögren’s syndrome. Furthermore, to discuss the potential capacity of currently used disease-modifying antirheumatic drugs (DMARDs) to target and modulate autophagic processes.