Autophagy contributes to IL-17-induced plasma cell differentiation in experimental autoimmune myocarditis

IL-17 in osteoarthritis: A narrative review

Osteoarthritis (OA) is a painful joint disease that is common among the middle-aged and elderly populations, with an increasing prevalence. Therapeutic options for OA are limited, and the pathogenic mechanism of OA remains unclear. The roles of cytokines and signaling pathways in the development of OA is a current research hot spot. Interleukin (IL)-17 is a pleiotropic inflammatory cytokine produced mainly by T helper 17 cells that has established roles in host defense, tissue repair, lymphoid tissue metabolism, tumor progression, and pathological processes of immune diseases, and studies in recent years have identified an important role for IL-17 in the progression of OA. This narrative review focuses on the mechanisms by which IL-17 contributes to articular cartilage degeneration and synovial inflammation in OA and discusses how IL-17 and the IL-17 signaling pathway affect the pathological process of OA. Additionally, therapeutic targets that have been proposed in recent years based on IL-17 and its pathway in OA are summarized as well as recent advances in the study of IL-17 pathway inhibitors and the potential challenges of their use for OA treatment.

Xanthohumol alleviates oxidative stress and impaired autophagy in experimental severe acute pancreatitis through inhibition of AKT/mTOR

Severe acute pancreatitis (SAP) is a lethal gastrointestinal disorder, yet no specific and effective treatment is available. Its pathogenesis involves inflammatory cascade, oxidative stress, and autophagy dysfunction. Xanthohumol (Xn) displays various medicinal properties, including anti-inflammation, antioxidative, and enhancing autophagic flux. However, it is unclear whether Xn inhibits SAP. This study investigated the efficacy of Xn on sodium taurocholate (NaT)-induced SAP (NaT-SAP) in vitro and in vivo. First, Xn attenuated biochemical and histopathological responses in NaT-SAP mice. And Xn reduced NaT-induced necrosis, inflammation, oxidative stress, and autophagy impairment. The mTOR activator MHY1485 and the AKT activator SC79 partly reversed the treatment effect of Xn. Overall, this is an innovative study to identify that Xn improved pancreatic injury by enhancing autophagic flux via inhibition of AKT/mTOR. Xn is expected to become a novel SAP therapeutic agent.

Integrative Analysis of Transcriptome and Metabolome Reveals Molecular Responses in Eriocheir sinensis with Hepatopancreatic Necrosis Disease

Hepatopancreatic necrosis disease (HPND) is a highly lethal disease that first emerged in 2015 in Jiangsu Province, China. So far, most researchers believe that this disease is caused by abiotic factors. However, its true pathogenic mechanism remains unknown. In this study, the effects of HPND on the metabolism and other biological indicators of the Chinese mitten crab (Eriocheir sinensis) were evaluated by integrating transcriptomics and metabolomics. Our findings demonstrate that the innate immunity, antioxidant activity, detoxification ability, and nervous system of the diseased crabs were affected. Additionally, metabolic pathways such as lipid metabolism, nucleotide metabolism, and protein metabolism were dysregulated, and energy production was slightly increased. Moreover, the IL-17 signaling pathway was activated and high levels of autophagy and apoptosis occurred in diseased crabs, which may be related to hepatopancreas damage. The abnormal mitochondrial function and possible anaerobic metabolism observed in our study suggested that functional hypoxia may be involved in HPND progression. Furthermore, the activities of carboxylesterase and acetylcholinesterase were significantly inhibited, indicating that the diseased crabs were likely stressed by pesticides such as pyrethroids. Collectively, our findings provide new insights into the molecular mechanisms altered in diseased crabs, as well as the etiology and pathogenic mechanisms of HPND.

Trehalose induces B cell autophagy to alleviate myocardial injury via the AMPK/ULK1 signalling pathway in acute viral myocarditis induced by Coxsackie virus B3

Viral myocarditis (VMC) is the main cause of sudden acute heart failure and cardiac death in adolescents; however, treatment for VMC is limited. Trehalose is a natural non-reductive disaccharide that protects against cardiovascular diseases by inducing autophagy. The protective effect of trehalose on VMC and the specific mechanism remains unclear. In this study, we established a VMC mouse model, treated with trehalose in vivo, and cultured B cells from VMC mice with trehalose in vitro to elucidate the effect of trehalose on B cells in acute VMC. Trehalose alleviated myocardial injury in VMC mice and increased the number of autophagosomes, LC3II/LC3I ratio, and expression level of LAMP2, whereas it decreased the expression of p62 in VMC-B cells. Bafilomycin A1 suppressed VMC-B cell autophagy induced by trehalose. At the mechanistic level, trehalose treatment significantly upregulated the phosphorylation of AMPK and ULK1 in VMC-B cells. Dorsomorphin and SBI-0206965 abolished the increased phosphorylation level and altered the expression levels of autophagy-related proteins. In conclusion, trehalose alleviates myocardial inflammatory damage of VMC by inducing B cell autophagy, mediated by the AMPK/ULK1 signalling pathway. Thus, trehalose may be a potentially useful molecule for alleviating myocardial injury in VMC.

Transplantation of Fibroblast Sheets with Blood Mononuclear Cell Culture Exerts Cardioprotective Effects by Enhancing Anti-Inflammation and Vasculogenic Potential in Rat Experimental Autoimmune Myocarditis Model

Simple Summary

Fulminant myocarditis (FM) is a serious inflammatory lesion of the myocardium accompanied by cardiac dysfunction, transitioning to end-stage heart failure. Due to such a difficult pathology, a therapeutic strategy that exerts a steadfast effect has yet to be developed. Blood mononuclear cells (MNCs) have been previously shown to enhance the quality and quantity of cellular fractions (QQMNCs) with anti-inflammatory and vasculogenic potential using the one culture system. The aim of this study was to investigate whether transplantation therapy with hybrid cell sheets of fibroblasts and QQMNCs improves cardiac function in a rat model with experimental autoimmune myocarditis (EAM) induced by purified porcine cardiac myosin. The transplanted hybrid cell sheet exerts cardioprotective effects against EAM, resulting in limited left ventricular remodeling and partially improved cardiac functions due to revascularization, anti-inflammation, and anti-fibrosis. Thus, tissue engineering using hybrid cell sheets of fibroblasts constructed with QQMNCs is expected to provide an effective therapeutic option for patients with severe FM.

Abstract

Fulminant myocarditis causes impaired cardiac function, leading to poor prognosis and heart failure. Cell sheet engineering is an effective therapeutic option for improving cardiac function. Naïve blood mononuclear cells (MNCs) have been previously shown to enhance the quality and quantity of cellular fractions (QQMNCs) with anti-inflammatory and vasculogenic potential using the one culture system. Herein, we investigated whether autologous cell sheet transplant with QQMNCs improves cardiac function in a rat model with experimental autoimmune myocarditis (EAM). Fibroblast sheets (F-sheet), prepared from EAM rats, were co-cultured with or without QQMNCs (QQ+F sheet) on temperature-responsive dishes. QQ+F sheet induced higher expression of anti-inflammatory and vasculogenic genes (Vegf-b, Hgf, Il-10, and Mrc1/Cd206) than the F sheet. EAM rats were transplanted with either QQ+F sheet or F-sheet, and the left ventricular (LV) hemodynamic analysis was performed using cardiac catheterization. Among the three groups (QQ+F sheet, F-sheet, operation control), the QQ+F sheet transplant group showed alleviation of end-diastolic pressure–volume relationship on a volume load to the same level as that in the healthy group. Histological analysis revealed that QQ+F sheet transplantation promoted revascularization and mitigated fibrosis by limiting LV remodeling. Therefore, autologous QQMNC-modified F-sheets may be a beneficial therapeutic option for EAM.

Pharmacological insights into autophagy modulation in autoimmune diseases

As a cellular bulk degradation and survival mechanism, autophagy is implicated in diverse biological processes. Genome-wide association studies have revealed the link between autophagy gene polymorphisms and susceptibility of autoimmune diseases including systemic lupus erythematosus (SLE) and inflammatory bowel disease (IBD), indicating that autophagy dysregulation may be involved in the development of autoimmune diseases. A series of autophagy modulators have displayed protective effects on autoimmune disease models, highlighting the emerging role of autophagy modulators in treating autoimmune diseases. This review explores the roles of autophagy in the autoimmune diseases, with emphasis on four major autoimmune diseases [SLE, rheumatoid arthritis (RA), IBD, and experimental autoimmune encephalomyelitis (EAE)]. More importantly, the therapeutic potentials of small molecular autophagy modulators (including autophagy inducers and inhibitors) on autoimmune diseases are comprehensively analyzed.

Sacubitril/Valsartan Alleviates Experimental Autoimmune Myocarditis by Inhibiting Th17 Cell Differentiation Independently of the NLRP3 Inflammasome Pathway

Sacubitril/valsartan (Sac/Val) is a recently approved drug that is commonly used for treatment of heart failure. Several studies indicated that Sac/Val also regulated the secretion of inflammatory factors. However, the effect and mechanism of this drug modulation of inflammatory immune responses are uncertain. In this study, an experimental autoimmune myocarditis (EAM) mouse model was established by injection of α-myosin-heavy chain peptides. The effect of oral Sac/Val on EAM was evaluated by histological staining of heart tissues, measurements of cardiac troponin T and inflammatory markers (IL-6 and hsCRP). The effects of Sac/Val on NLRP3 inflammasome activation and Th1/Th17 cell differentiation were also determined. To further explore the signaling pathways, the expressions of cardiac soluble guanylyl cyclase (sGC) and NF-κB p65 were investigated. The results showed that Sac/Val downregulated the inflammatory response and attenuated the severity of EAM, but did not influence NLRP3 inflammasomes activation. Moreover, Sac/Val treatment inhibited cardiac Th17 cell differentiation, and this might be associated with sGC/NF-κB p65 signaling pathway. These findings indicate the potential use of Sac/Val for treatment of myocarditis.

MiR-125b enhances autophagic flux to improve septic cardiomyopathy via targeting STAT3/HMGB1

We explore the role of miR-125b in septic cardiomyopathy, focusing on miR-125b/STAT3/HMGB1 axis. CLP mouse model and LPS-stimulated primary rat cardiomyocytes (CMs) and H9C2 cell were used as in vivo and in vitro models of septic cardiomyopathy, respectively. qRT-PCR and western blot were performed to measure expression levels of miR-125b, STAT3, HMGB1, and autophagy-related proteins. MTT assay was employed to examine LPS toxicity. Dual luciferase activity assay and CHIP were performed to validate interactions of miR-125b/STAT3 and STAT3/HMGB1 promoter. Immunostaining was used to assess the level of autophagic flux. ROS level was measured by fluorescence assay. Heart functions were examined via intracoronary Doppler ultrasound. miR-125b was diminished while STAT3 and HMGB1 were elevated in the heart tissue following CLP surgery and in LPS-treated H9C2 cells. LPS treatment up-regulated ROS generation and suppressed autophagic flux. Overexpression of miR-125b mimics or knockdown of STAT3 or HMGB1 alleviated LPS-induced hindrance of autophagic flux and ROS production. miR-125b directly targeted STAT3 mRNA and STAT3 bound with HMGB1 promoter. Overexpression of miR-125b mitigated myocardial dysfunction induced by CLP in vivo. Hyperactivation of STAT3/HMGB1 caused by reduced miR-125b contributes to ROS generation and the hindrance of autophagic flux during septic cardiomyopathy, leading to myocardial dysfunction.

The Role of Autophagy in Anti-Cancer and Health Promoting Effects of Cordycepin

Cordycepin is an adenosine derivative isolated from Cordyceps sinensis, which has been used as an herbal complementary and alternative medicine with various biological activities. The general anti-cancer mechanisms of cordycepin are regulated by the adenosine A3 receptor, epidermal growth factor receptor (EGFR), mitogen-activated protein kinases (MAPKs), and glycogen synthase kinase (GSK)-3β, leading to cell cycle arrest or apoptosis. Notably, cordycepin also induces autophagy to trigger cell death, inhibits tumor metastasis, and modulates the immune system. Since the dysregulation of autophagy is associated with cancers and neuron, immune, and kidney diseases, cordycepin is considered an alternative treatment because of the involvement of cordycepin in autophagic signaling. However, the profound mechanism of autophagy induction by cordycepin has never been reviewed in detail. Therefore, in this article, we reviewed the anti-cancer and health-promoting effects of cordycepin in the neurons, kidneys, and the immune system through diverse mechanisms, including autophagy induction. We also suggest that formulation changes for cordycepin could enhance its bioactivity and bioavailability and lower its toxicity for future applications. A comprehensive understanding of the autophagy mechanism would provide novel mechanistic insight into the anti-cancer and health-promoting effects of cordycepin.

RANKL expression of primary osteoblasts is enhanced by an IL-17-mediated JAK2/STAT3 pathway through autophagy suppression

Objective: Interleukin-17 (IL-17), produced by T helper (Th)-17 cells, is a potent regulator of bone homeostasis. Osteoblasts are key cells that orchestrate inflammatory bone destruction and bone remodeling. This study examines the effect of different concentrations of IL-17 on osteogenesis and receptor activator of nuclear factor-kappa B ligand (RANKL) expression of primary osteoblasts.Methods: First, the growth of primary osteoblasts was evaluated. Second, we assessed the effects of IL-17 on the level of autophagy and the related Janus activated kinase 2 (JAK2) and downstream signal transducer and activator of transcription 3 (STAT3) signaling pathway. Next, osteogenic activity in different concentrations of IL-17 was tested. Finally, the specific JAK2/STAT3 signaling pathway inhibitor AG490 and autophagy inhibitor 3-MA were used to investigate the involvement of this pathway and autophagy in IL-17-induced regulation of RANKL expression.Results: Initially, we found that IL-17 treatment promoted growth of osteoblasts in a time- and dose-dependent manner. Next, we showed that low levels of IL-17 promoted autophagy activity, whereas the opposite was observed at high levels of IL-17. Moreover, high levels of IL-17 activated the JAK2/STAT3 signaling pathway, although this effect was reversed by upregulation of autophagy. Furthermore, our findings indicated that high concentrations of IL-17 promoted the differentiation, calcification, and RANKL expression of murine osteoblasts via activation of the JAK2/STAT3 pathway. Importantly, downregulation of autophagy at high IL-17 concentrations further enhanced RANKL expression via suppressing the JAK2/STAT3 cascade.Conclusion: Overall, our findings demonstrate, for the first time, that IL-17 modulates RANKL expression of osteoblasts through an autophagy-JAK2-STAT3 signaling pathway, thus affecting bone metabolism.

Role of Pro-inflammatory Cytokines in Regulation of Skeletal Muscle Metabolism: A Systematic Review

Background:

Metabolic pathways perturbations lead to skeletal muscular atrophy in the cachexia and sarcopenia due to increased catabolism. Pro-inflammatory cytokines induce the catabolic pathways that impair the muscle integrity and function. Hence, this review primarily concentrates on the effects of pro-inflammatory cytokines in regulation of skeletal muscle metabolism.

Objective:

This review will discuss the role of pro-inflammatory cytokines in skeletal muscles during muscle wasting conditions. Moreover, the coordination among the pro-inflammatory cytokines and their regulated molecular signaling pathways which increase the protein degradation will be discussed.

Results:

During normal conditions, pro-inflammatory cytokines are required to balance anabolism and catabolism and to maintain normal myogenesis process. However, during muscle wasting their enhanced expression leads to marked destructive metabolism in the skeletal muscles. Proinflammatory cytokines primarily exert their effects by increasing the expression of calpains and E3 ligases as well as of Nf-κB, required for protein breakdown and local inflammation. Proinflammatory cytokines also locally suppress the IGF-1and insulin functions, hence increase the FoxO activation and decrease the Akt function, the central point of carbohydrates lipid and protein metabolism.

Conclusion:

Current advancements have revealed that the muscle mass loss during skeletal muscular atrophy is multifactorial. Despite great efforts, not even a single FDA approved drug is available in the market. It indicates the well-organized coordination among the pro-inflammatory cytokines that need to be further understood and explored.

PPARα suppresses Th17 cell differentiation through IL-6/STAT3/RORγt pathway in experimental autoimmune myocarditis

Family members of peroxisome proliferator-activated receptors (PPARs), such as PPARγ, have been shown to be effective in regulating T helper 17 (Th17) cell differentiation. However, whether PPARα, another important family member of PPARs, contributes to Th17 cell differentiation remains controversial. In the present study, we show that PPARα may be a negative regulator of Th17 cell differentiation. In CD4⁺ T cells from PPARα knockout mice, PPARα deficiency enhances IL-17 and IL-6 levels and promotes Th17 cell differentiation. In contrast, in CD4⁺ T cells from wild type mice, PPARα activation suppresses Th17 cell differentiation. Furthermore, IL-6 neutralizing antibody dose-dependently reduces the activity of STAT3 and down-regulates the protein expression of RORγt in CD4⁺ T cells from PPARα knockout mice but has no effect on that of wild type mice. On the other hand, in isolated CD4⁺ T cells from experimental autoimmune myocarditis (EAM) rats, PPARα agonist Fenofibrate decreased the expression of IL-17 and RORγt, increased the expression of Foxp3, while PPARα antagonist MK886 reversed these effects. Importantly, in vivo activation of PPARα ameliorates EAM by suppressing Th17 cell differentiation through reducing the expression of RORγt and phosphorylated STAT3 that are upregulated in EAM hearts. These results imply that PPARα suppresses Th17 cell differentiation through IL-6/STAT3/RORγt signaling pathway and suggest that PPARα may become a molecular target for treating autoimmune myocarditis.

The Therapeutic and Pathogenic Role of Autophagy in Autoimmune Diseases

Autophagy is a complicated cellular mechanism that maintains cellular and tissue homeostasis and integrity via degradation of senescent, defective subcellular organelles, infectious agents, and misfolded proteins. Accumulating evidence has shown that autophagy is involved in numerous immune processes, such as removal of intracellular bacteria, cytokine production, autoantigen presentation, and survival of lymphocytes, indicating an apparent and important role in innate and adaptive immune responses. Indeed, in genome-wide association studies, autophagy-related gene polymorphisms have been suggested to be associated with the pathogenesis of several autoimmune and inflammatory disorders, such as systemic lupus erythematosus, psoriasis, rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis. In addition, conditional knockdown of autophagy-related genes in mice displayed therapeutic effects on several autoimmune disease models by reducing levels of inflammatory cytokines and autoreactive immune cells. However, the inhibition of autophagy accelerates the progress of some inflammatory and autoimmune diseases via promotion of inflammatory cytokine production. Therefore, this review will summarize the current knowledge of autophagy in immune regulation and discuss the therapeutic and pathogenic role of autophagy in autoimmune diseases to broaden our understanding of the etiopathogenesis of autoimmune diseases and shed light on autophagy-mediated therapies.

Autophagy and proinflammatory cytokines: Interactions and clinical implications

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

Role of Hypoxia-Inducible Factors 1α (HIF1α) in SH-SY5Y Cell Autophagy Induced by Oxygen-Glucose Deprivation

Background

HIF-1α plays an important role in hypoxia-ischemia brain damage. Accumulating evidences demonstrates that HIF-1α can contribute to cell autophagy. Oxygen-glucose deprivation (OGD) is a commonly used ischemic model in vitro. Our study was performed to investigate the influences of HIF-1α on autophagy in SH-SY5Y cells under OGD treatment.

Material/Methods

An OGD model was constructed in SH-SY5Y cells. PI method and MTT assay were used to test cell death and viability, respectively. Western blot assay was used to estimate the protein levels of HIF-1α and LC3. Quantitative GFP-LC3 light microscopy autophagy assay was performed for SH-SY5Y cells. 2ME2 and siRNA-HIF-1α were applied to investigate the effects of HIF-1α-knockdown on LC3 expression. Additionally, 3-MA (autophagy inhibitor) and autophagy inducer rapamycin (Rapa) were used to investigate the effects of autophagy on cell survival under OGD condition.

Results

Under OGD, the apoptosis of SH-SY5Ycells was increased while cell viability rate was decreased. The expression of HIF-1α was increased along with the advancement of OGD treatment and achieved the highest level at 24 h. However, inhibiting HIF-1α expression decreased the cell apoptosis and increased cell viability. LC3-II expression was gradually increased with the duration of OGD condition and knockdown of HIF-1α resulted in decreased expression of LC3. Inhibiting autophagy significantly enhanced the viability and reduced the apoptosis of SH-SY5Y cells, while enhancing autophagy showed the opposite effects.

Conclusions

Enhanced expression of HIF-1α may be related to autophagy activation in SH-SY5Y cells, thus contributing to ischemic/hypoxic brain damage.

Identification of targeting peptides for the diagnosis of myocarditis

Aim: Current diagnostic tests for myocarditis are invasive and have low diagnostic value. Our aim was to identify potential targeting peptides to detect early myocarditis following intravenous delivery. Materials & methods: We used an animal model of experimental autoimmune myocarditis and a phage display library to identify potential targeting peptides. After several steps, we selected two peptides, MyH-PhD-05 and MyH-PhD-120, for in vivo screening using fluorescent imaging. Immunofluorescence and proteonomic analysis was used to identify potential cellular and molecular targets of MyH-PhD-05. Echocardiography was used to assess functional changes. Results: Peptide MyH-PhD-05 was able to detect animals with severe myocarditis even in the absence of functional changes. Immunofluorescence demonstrated that MyH-PhD-05 colocalizes with CD4+ T cells and monocytes (CD11b+) in cardiac infiltrates. Conclusion: We identified potential targeting peptides for the diagnosis of myocarditis. Future studies will focus on better identification of potential targets and translating this technology to clinically relevant imaging modalities.

Autophagy-independent increase of ATG5 expression in T cells of multiple sclerosis patients

Autophagy, a process of controlled self-digestion which regulates cell homeostasis, is involved in innate and adaptive immunity. We investigated the expression of autophagy genes and autophagic activity in distinct lymphocyte populations in treatment-naive MS patients. The mRNA and protein levels of autophagy-related (ATG)5, required for autophagosome formation, were increased in CD4⁺ and CD4^- T cells, but not B cells of MS patients compared to control subjects. The expression of other investigated autophagy genes, as well as the autophagic activity, did not significantly differ between the two groups. ATG5 mRNA levels in CD4⁺ T cells from MS patients were positively correlated with those of the proinflammatory cytokine tumor necrosis factor. These data suggest that autophagy-independent increase in ATG5 expression might be associated with the proinflammatory capacity of T cells in multiple sclerosis.

PI3K/AKT/mTOR activation and autophagy inhibition plays a key role in increased cholesterol during IL-17A mediated inflammatory response in psoriasis

Psoriasis is an immune-mediated inflammatory disease of the skin. Previous studies including ours have shown that IL-17A plays a major role in its pathogenesis; however, its precise molecular mechanism of action is not well understood. Cytokines like TNF α and IL-23 are also important in mediating the disease and some studies have also reported autophagy as a novel mechanism by which cytokines controls the immune response. Herein, we investigated the effect of IL-17A on autophagy and reveal crosstalk between autophagy and cholesterol signaling in keratinocytes. Our results suggest that IL-17A stimulated keratinocytes activated PI3K/AKT/mTOR signaling and inhibited autophagy by simultaneously inhibiting autophagosome formation and enhancing autophagic flux. Western blotting was utilized to detect the expression of autophagic markers (LC3 and p62), PI3K, mTOR and AKT. Induction of autophagy by mTOR inhibitor rapamycin and/or starvation also inhibited the levels of IL-17A secreted IL-8, CCL20 and S100A7 in keratinocytes. Herein, we also observed that inhibition of autophagy by IL-17A was accompanied by enhanced cellular cholesterol levels which in turn regulated the autophagic flux. To investigate crosstalk between autophagy and cellular cholesterol, we used methyl-β-cyclodextrin (MβCD), which disrupts detergent-insoluble microdomains (DIMs) by depleting cells of cholesterol and checked autophagy. Decreased expression of LC3-II in psoriatic lesional skin compared to non-lesional skin and induction of autophagy by anti-psoriatic drug methotrexate in keratinocytes further confirms the role of autophagy in psoriasis. Our findings suggest that modulators of autophagy and/or cholesterol levels may be developed, and also may lead to new therapeutic agents for psoriasis treatment.

IL17A augments autophagy in Mycobacterium tuberculosis-infected monocytes from patients with active tuberculosis in association with the severity of the disease

During mycobacterial infection, macroautophagy/autophagy, a process modulated by cytokines, is essential for mounting successful host responses. Autophagy collaborates with human immune responses against Mycobacterium tuberculosis (Mt) in association with specific IFNG secreted against the pathogen. However, IFNG alone is not sufficient to the complete bacterial eradication, and other cytokines might be required. Actually, induction of Th1 and Th17 immune responses are required for protection against Mt. Accordingly, we showed that IL17A and IFNG expression in lymphocytes from tuberculosis patients correlates with disease severity. Here we investigate the role of IFNG and IL17A during autophagy in monocytes infected with Mt H37Rv or the mutant MtΔRD1. Patients with active disease were classified as high responder (HR) or low responder (LR) according to their T cell responses against Mt. IL17A augmented autophagy in infected monocytes from HR patients through a mechanism that activated MAPK1/ERK2-MAPK3/ERK1 but, during infection of monocytes from LR patients, IL17A had no effect on the autophagic response. In contrast, addition of IFNG to infected monocytes, increased autophagy by activating MAPK14/p38 α both in HR and LR patients. Interestingly, proteins codified in the RD1 region did not interfere with IFNG and IL17A autophagy induction. Therefore, in severe tuberculosis patients' monocytes, IL17A was unable to augment autophagy because of a defect in the MAPK1/3 signaling pathway. In contrast, both IFNG and IL17A increased autophagy levels in patients with strong immunity to Mt, promoting mycobacterial killing. Our findings might contribute to recognize new targets for the development of novel therapeutic tools to fight the pathogen.

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

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