mTOR-dependent autophagy contributes to end-organ resistance and serves as target for treatment in autoimmune disease

Redox mechanisms in autoimmune thyroid eye disease

Thyroid eye disease (TED) is an autoimmune condition affecting the orbit and the eye with its adnexa, often occurring as an extrathyroidal complication of Graves' disease (GD). Orbital inflammatory infiltration and the stimulation of orbital fibroblasts, triggering de novo adipogenesis, an overproduction of hyaluronan, myofibroblast differentiation, and eventual tissue fibrosis are hallmarks of the disease. Notably, several redox signaling pathways have been shown to intensify inflammation and to promote adipogenesis, myofibroblast differentiation, and fibrogenesis by upregulating potent cytokines, such as interleukin (IL)-1β, IL-6, and transforming growth factor (TGF)-β. While existing treatment options can manage symptoms and potentially halt disease progression, they come with drawbacks such as relapses, side effects, and chronic adverse effects on the optic nerve. Currently, several studies shed light on the pathogenetic contributions of emerging factors within immunological cascades and chronic oxidative stress. This review article provides an overview on the latest advancements in understanding the pathophysiology of TED, with a special focus of the interplay between oxidative stress, immunological mechanisms and environmental factors. Furthermore, cutting-edge therapeutic approaches targeting redox mechanisms will be presented and discussed.

Targeting toll-like receptor 4 (TLR4) and the NLRP3 inflammasome: Novel and emerging therapeutic targets for hyperuricaemia nephropathy

The clinical manifestation of hyperuricaemia, known as hyperuricaemia nephropathy, is relatively common. Its pathophysiology is largely based on chronic inflammation in circulatory and renal tissues. Toll-like receptor 4 (TLR4), a subclass of innate immune receptors, detects both pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), initiating inflammatory and immune responses that lead to the release of pro-inflammatory cytokines interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α). These cytokines are pivotal in renal inflammation, especially in conditions like hyperuricaemia, acute renal injury, ischemia-reperfusion injury, and acute renal failure. The nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, an essential component of the innate immune signaling complex, plays a central role in inflammation. It finely regulates the activation of caspase-1 and the production and secretion of the pro-inflammatory cytokine IL-1β, mediating and amplifying the inflammatory cascade response. Activation of TLR4 indirectly promotes the assembly of the NLRP3 inflammasome by regulating the nuclear factor kappa B (NF-κB) signaling pathway, thereby amplifying the inflammatory process and playing a significant pro-inflammatory role in hyperuricaemia nephropathy. TLR4 and NLRP3 inflammasome are anticipated to be novel markers and therapeutic targets for assessing treatment efficacy and prognosis in hyperuricaemia nephropathy. This paper provides a comprehensive overview of the structural composition and biological functions of TLR4 and NLRP3 inflammasome and systematically reviews their relevance in the pathogenesis of hyperuricaemia nephropathy.

Autophagy dysregulation in trichloroethene-mediated inflammation and autoimmune response

Trichloroethene (TCE), an organic solvent extensively used for degreasing metals, can cause inflammatory autoimmune disorders [i.e., systemic lupus erythematosus (SLE) and autoimmune hepatitis] from both environmental and occupational exposure. Autophagy has emerged as a pivotal pathogenic factor in various autoimmune diseases. However, role of autophagy dysregulation in TCE-mediated autoimmunity is largely unknown. Here, we investigate whether autophagy dysregulation contributes to pathogenesis of TCE-mediated autoimmune responses. Using our established mouse model, we observed TCE-treated mice had elevated MDA-protein adducts, microtubule-associated protein light chain 3 conversion (LC3-II/LC3-I), beclin-1, phosphorylation of AMP-activated protein kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) phosphorylation in the livers of MRL+ /+ mice. Suppression of oxidative stress with antioxidant N-acetylcysteine (NAC) effectively blocked TCE-mediated induction of autophagy markers. On the other hand, pharmacological autophagy induction with rapamycin significantly reduced TCE-mediated hepatic inflammation (NLRP3, ASC, Caspase1 and IL1-β mRNA levels), systemic cytokines (IL-12 and IL-17) and autoimmune responses (ANA and anti-dsDNA levels). Taken together, these results suggest that autophagy plays a protective role against TCE-mediated hepatic inflammation and autoimmunity in MRL+ /+ mice. These novel findings on the regulation of autophagy could help in designing therapeutic strategies for chemical exposure-mediated autoimmune responses.

Activation of TLR4 induces inflammatory muscle injury via mTOR and NF-κB pathways in experimental autoimmune myositis mice

Idiopathic inflammatory myopathy (IIM) is an autoimmune disease that invades skeletal muscle; however, the etiology of IIM is still poorly understood. Toll-like receptor (TLR) 4 has been widely reported to take part in the autoimmune inflammation of IIMs. The mammalian target of rapamycin, mTOR, is a key central substance which mediates immune responses and metabolic changes, and also has been confirmed to be involved in the pathogenesis of IIMs. However, the interconnectedness between TLR4 and mTOR in IIM inflammation has not been fully elucidated. We hypothesized that TLR4 may play an important role in IIM inflammatory muscle injury by regulating mTOR. Mice were divided into four groups: a normal control group, IIM animal model (experimental autoimmune myositis, EAM) group, TAK242 intervention group and rapamycin (RAPA) intervention group. The results of EAM mice showed that TLR4, mTOR, nuclear factor-kappa B (NF-κB) and inflammatory factors interleukin-17A (IL-17A) and interferon γ (IFN-γ) mRNA levels were significantly upregulated. These factors were positively correlated with the degree of muscle inflammatory injury. When EAM mice were given the antagonist TAK242 to inhibit the TLR4 pathway, the results demonstrated that both mTOR and NF-κB were downregulated in the muscle of the mice. Muscle staining showed that the inflammatory injury was alleviated and the EAM mouse muscle strength was improved. Then, RAPA was used to inhibit the mTOR pathway, and the inflammatory factors IL-17A and IFN-γ were downregulated in EAM mouse muscle and serum. Consistently, muscle inflammatory injury was significantly reduced, and muscle strength was significantly improved. Our results suggest that TLR4 may regulate inflammatory muscle injury in EAM by activating the mTOR and NF-κB pathways, which provides both an experimental complement for the pathological mechanism of IIM and an encouraging target for the selection of effective treatments.

Circ-EEF2 facilitated autophagy via interaction with mir-6881-3p and ANXA2 in EOC

Circular RNAs, a special class of non-coding RNA with closed circular structure, have been increasingly proven to be involved in the progression of various tumors. However, the biological functions of circular RNAs in epithelial ovarian cancer (EOC) tissues remain a mystery. In this study, we detected the function of circEEF2 (has-circ-0048559) in EOC tissues. Firstly, the basic characteristics including closed circular structure and spliced mature sequence length of circEEF2 were confirmed. The location and expression in EOC tissues was detected by fluorescence in situ hybridization (FISH). The regulatory effect of circEEF2 on autophagy, proliferation, and invasion were investigated in SKOV3 and A2780 cells. The relationship between circEEF2 and mir-6881-3p was confirmed using dual-luciferase reporter gene assay. The binding of circEEF2 with ANXA2 was confirmed using RNA-pulldown assay and MALDI-TOF-MS. We found that the expression level of circEEF2 was higher in EOC tissue than in normal tissue. CircEEF2 promoted autophagy, proliferation, and invasion. CircEEF2-regulated EOC proliferation and invasion are closely related to the occurrence of autophagy. Mechanistically, circEEF2 harbor miR-6881-3p to upregulate the latter's targets ATG5 and ATG7. Moreover, circEEF2 could directly bind with ANXA2 to inhibit the expression of p-mTOR. In conclusion, findings of the current study illustrate that circEEF2 promoted autophagy, proliferation, and invasion of EOC by interacting with miR-6881-3p and ANXA2.

Sirolimus as Rescue Therapy for Refractory/Relapsed Immune Thrombocytopenia: Results of a Single-Center, Prospective, Single-Arm Study

Immune thrombocytopenia (ITP) is an autoimmune disease which arises due to self-destruction of circulating platelets. Failure to respond or maintain a response to first-line treatment can lead to refractory/relapsed (R/R) ITP. The mechanism remains complicated and lacks a standard clinical treatment. Sirolimus (SRL) is a mammalian target of rapamycin (mTOR) inhibitor that has been demonstrated to inhibit lymphocyte activity, indicating potential for SRL in treatment of ITP. Activation of the mTOR pathway in autoimmune diseases suggests that SRL might be a useful agent for treating ITP. Accordingly, we initiated an open-label, prospective clinical trial using SRL for patients with R/R ITP (ChiCTR-ONC-17012126). The trial enrolled 86 patients, each dosed with 2-4 mg/day of SRL. By the third month, 40% of patients (34 of 86) achieved complete remission (CR) and 45% of patients (39 of 86) achieved partial remission (PR), whereby establishing an overall response rate (ORR) of 85%. By 6 months of treatment, 41% of patients (32 of 78) achieved CR and 29% of patients (23 of 78) achieved PR, establishing an ORR of 70% without serious side effects. After 12 months follow-up, the ORR remained at 65%. We also found that SRL treatment exhibited higher efficacy in achieving CR in ITP patients who were younger than 40 years old or steroid dependent by univariate analysis. Importantly, in patients who responded, SRL treatment was associated with a reduction in the percentage of Th2, Th17 cells, and increase in the percentage of M-MDSCs and Tregs, indicating that SRL may reestablish peripheral tolerance. Taken together, Sirolimus demonstrated efficacy as a second-line agent for R/R ITP.

Roles of mTOR Signaling in Tissue Regeneration

The mammalian target of rapamycin (mTOR), is a serine/threonine protein kinase and belongs to the phosphatidylinositol 3-kinase (PI3K)-related kinase (PIKK) family. mTOR interacts with other subunits to form two distinct complexes, mTORC1 and mTORC2. mTORC1 coordinates cell growth and metabolism in response to environmental input, including growth factors, amino acid, energy and stress. mTORC2 mainly controls cell survival and migration through phosphorylating glucocorticoid-regulated kinase (SGK), protein kinase B (Akt), and protein kinase C (PKC) kinase families. The dysregulation of mTOR is involved in human diseases including cancer, cardiovascular diseases, neurodegenerative diseases, and epilepsy. Tissue damage caused by trauma, diseases or aging disrupt the tissue functions. Tissue regeneration after injuries is of significance for recovering the tissue homeostasis and functions. Mammals have very limited regenerative capacity in multiple tissues and organs, such as the heart and central nervous system (CNS). Thereby, understanding the mechanisms underlying tissue regeneration is crucial for tissue repair and regenerative medicine. mTOR is activated in multiple tissue injuries. In this review, we summarize the roles of mTOR signaling in tissue regeneration such as neurons, muscles, the liver and the intestine.

FAM83D inhibits autophagy and promotes proliferation and invasion of ovarian cancer cells via PI3K/AKT/mTOR pathway

Ovarian cancer is one of the most lethal malignant tumors in women. The family with sequence similarity 83, member D (FAM83D) plays an important role in several cancers, but its function and underlying mechanism in ovarian cancer remain unknown. To investigate the role of FAM83D in ovarian cancer, the expression of FAM83D was determined by immunohistochemistry in tissue microarray slide. Cellular proliferation and invasion were detected by 5-Ethynyl-2'-deoxyuridine assays and transwell invasion assays. The correlations between FAM83D and autophagy were detected by western blot analysis and confocal microscopy. Western blot analysis was used to identify the protein expression of FAM83D, phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), mammalian target of rapamycin (mTOR) and Sequestosome 1 (P62). Tumorigenesis in nude mice was used to explore the function of FAM83D in vivo. We found high expression level of FAM83D in ovarian cancer tissues as compared to the normal ovarian tissues. Knockdown of FAM83D in SKOV3 cells enhanced autophagy and inhibited the proliferation and invasion in vitro, whereas ectopic expression of FAM83D in A2780 cells exerted an opposite effect. Mechanistically, overexpression of FAM83D activated the PI3K/AKT/mTOR pathway, and Torin1 could suppress FAM83D-induced cell proliferation and invasion. In vivo, overexpression FAM83D promoted tumor growth. Overall, FAM83D promoted ovarian cancer cell invasion and proliferation, while inhibited autophagy via the PI3K/AKT/mTOR signaling pathway. Our results suggest that FAM83D may be a candidate oncogene in ovarian cancer, which provides a fresh perspective of FAM83D in ovarian cancer.

ALKBH5 inhibited autophagy of epithelial ovarian cancer through miR-7 and BCL-2

Background

ALKBH5 regulated the malignant behavior of breast cancer and glioblastoma. However, the expression and function of ALKBH5 in epithelial ovarian cancer have not yet been determined. In the present study, we investigated the expression and function of ALKBH5 in epithelial ovarian cancer with respect to its potential role in the tumorigenesis of the disease as well as an early diagnostic marker.

Methods

Immunohistochemistry and western blot were used to detect protein expression. Gene silencing and over-expression experiment were used to study gene function. Cell proliferation assay and Matrigel invasion assays were used to detect cell proliferation and invasion, respectively. The nude mouse tumor formation experiment was used to evaluate the growth of cells in vivo.

Results

The expression of ALKBH5 was found to be increased in epithelial ovarian cancer tissue as compared to the normal ovarian tissues. The silencing of ALKBH5 in SKOV3 cells enhanced the autophagy and inhibited the proliferation and invasion in vitro and in vivo, whereas the ectopic expression of ALKBH5 in A2780 cells exerted an opposite effect. Mechanical study revealed that ALKBH5 physically interacted with HuR. ALKBH5 activated EGFR-PIK3CA-AKT-mTOR signaling pathway. Also, ALKBH5 enhanced the stability of BCL-2 mRNA and promoted the interaction between Bcl-2 and Beclin1.

Conclusion

Overall, the present study identified ALKBH5 as a candidate oncogene in epithelial ovarian cancer and a potential target for ovarian cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1159-2) contains supplementary material, which is available to authorized users.