USP16-mediated deubiquitination of calcineurin A controls peripheral T cell maintenance

Trim21-mediated CCT2 ubiquitination suppresses malignant progression and promotes CD4+T cell activation in breast cancer

Breast cancer remains a significant global health challenge, and its mechanisms of progression and metastasis are still not fully understood. In this study, analysis of TCGA and GEO datasets revealed a significant increase in CCT2 expression in breast cancer tissues, which was associated with poor prognosis in breast cancer patients. Functional analysis revealed that CCT2 promoted breast cancer growth and metastasis through activation of the JAK2/STAT3 signaling pathway. Additionally, the E3 ubiquitin ligase Trim21 facilitated CCT2 ubiquitination and degradation, significantly reversing the protumor effects of CCT2. Most interestingly, we discovered that exosomal CCT2 derived from breast cancer cells suppressed the activation and proinflammatory cytokine secretion of CD4+ T cell. Mechanistically, exosomal CCT2 constrained Ca2+-NFAT1 signaling, thereby reducing CD40L expression on CD4+ T cell. These findings highlight CCT2 upregulation as a potential driver of breast cancer progression and immune evasion. Our study provides new insights into the molecular mechanisms underlying breast cancer progression, suggesting that CCT2 is a promising therapeutic target and prognostic predictor for breast cancer.

Deubiquitinases in muscle physiology and disorders

In vivo, muscle and neuronal cells are post-mitotic, and their function is predominantly regulated by proteostasis, a multilayer molecular process that maintains a delicate balance of protein homeostasis. The ubiquitin-proteasome system (UPS) is a key regulator of proteostasis. A dysfunctional UPS is a hallmark of muscle ageing and is often impacted in neuromuscular disorders (NMDs). Malfunction of the UPS often results in aberrant protein accumulation which can lead to protein aggregation and/or mis-localization affecting its function. Deubiquitinating enzymes (DUBs) are key players in the UPS, controlling protein turnover and maintaining the free ubiquitin pool. Several mutations in DUB encoding genes are linked to human NMDs, such as ATXN3, OTUD7A, UCHL1 and USP14, whilst other NMDs are associated with dysregulation of DUB expression. USP5, USP9X and USP14 are implicated in synaptic transmission and remodeling at the neuromuscular junction. Mice lacking USP19 show increased maintenance of lean muscle mass. In this review, we highlight the involvement of DUBs in muscle physiology and NMDs, particularly in processes affecting muscle regeneration, degeneration and inflammation following muscle injury. DUBs have recently garnered much respect as promising drug targets, and their roles in muscle maturation, regeneration and degeneration may provide the framework for novel therapeutics to treat muscular disorders including NMDs, sarcopenia and cachexia.

SMURF1 controls the PPP3/calcineurin complex and TFEB at a regulatory node for lysosomal biogenesis

Macroautophagy/autophagy is a homeostatic process in response to multiple signaling, such as the lysosome-dependent recycling process of cellular components. Starvation-induced MTOR inactivation and PPP3/calcineurin activation were shown to promote the nuclear translocation of TFEB. However, the mechanisms via which signals from endomembrane damage are transmitted to activate PPP3/calcineurin and orchestrate autophagic responses remain unknown. This study aimed to show that autophagy regulator SMURF1 controlled TFEB nuclear import for transcriptional activation of the lysosomal biogenesis. We showed that blocking SMURF1 affected lysosomal biogenesis in response to lysosomal damage by preventing TFEB nuclear translocation. It revealed galectins recognized endolysosomal damage, and led to recruitment of SMURF1 and the PPP3/calcineurin apparatus on lysosomes. SMURF1 interacts with both LGALS3 and PPP3CB to form the LGALS3-SMURF1-PPP3/calcineurin complex. Importantly, this complex further stabilizes TFEB, thereby activating TFEB for lysosomal biogenesis. We determined that LLOMe-mediated TFEB nuclear import is dependent on SMURF1 under the condition of MTORC1 inhibition. In addition, SMURF1 is required for PPP3/calcineurin activity as a positive regulator of TFEB. SMURF1 controlled the phosphatase activity of the PPP3CB by promoting the dissociation of its autoinhibitory domain (AID) from its catalytic domain (CD). Overexpression of SMURF1 showed similar effects as the constitutive activation of PPP3CB. Thus, SMURF1, which bridges environmental stress with the core autophagosomal and autolysosomal machinery, interacted with endomembrane sensor LGALS3 and phosphatase PPP3CB to control TFEB activation.Abbreviations: ATG: autophagy-related; LLOMe: L-Leucyl-L-Leucine methyl ester; ML-SA1: mucolipin synthetic agonist 1; MTOR: mechanistic target of rapamycin kinase; PPP3CB: protein phosphatase 3 catalytic subunit beta; RPS6KB1/p70S6K: ribosomal protein S6 kinase B1; SMURF1: SMAD specific E3 ubiquitin protein ligase 1; TFEB: transcription factor EB.

O-GlcNAcylation stimulates the deubiquitination activity of USP16 and regulates cell cycle progression

Histone 2A monoubiquitination (uH2A) underscores a key epigenetic regulation of gene expression. In this report, we show that the deubiquitinase for uH2A, ubiquitin-specific peptidase 16 (USP16), is modified by O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation involves the installation of the O-GlcNAc moiety to Ser/Thr residues. It crosstalks with Ser/Thr phosphorylation, affects protein-protein interaction, alters enzyme activity or protein folding, and changes protein subcellular localization. In our study, we first confirmed that USP16 is glycosylated on Thr203 and Ser214, as reported in a previous chemoenzymatic screen. We then discovered that mutation of the O-GlcNAcylation site Thr203, which is adjacent to deubiquitination-required Cys204, reduces the deubiquitination activity toward H2AK119ub in vitro and in cells, while mutation on Ser214 had the opposite effects. Using USP16 Ser552 phosphorylation-specific antibodies, we demonstrated that O-GlcNAcylation antagonizes cyclin-dependent kinase 1-mediated phosphorylation and promotes USP16 nuclear export. O-GlcNAcylation of USP16 is also required for deubiquitination of Polo-like kinase 1, a mitotic master kinase, and the subsequent chromosome segregation and cytokinesis. In summary, our study revealed that O-GlcNAcylation of USP16 at Thr203 and Ser214 coordinates deubiquitination of uH2A and Polo-like kinase 1, thus ensuring proper cell cycle progression.

Puerarin Ameliorated PCOS through Preventing Mitochondrial Dysfunction Dependent on the Maintenance of Intracellular Calcium Homeostasis

Polycystic ovarian syndrome (PCOS) is the major cause of infertility in reproductive women, but no universal drug is feasible. Although puerarin clinically treats cerebrovascular and cardiovascular diseases, its curative effect on PCOS remains elusive. The present study discovered that administration of puerarin restored estrous cycle of PCOS mice and diminished the number of cystic follicles with the concomitant recovery for circulating testosterone, LH and FSH levels, and LH/FSH ratio, indicating the therapeutic role of puerarin in PCOS. KEGG analysis of differential genes between PCOS and control revealed the enrichment in MAPK and calcium signaling pathway. Application of puerarin restricted the phosphorylation of ERK1/2 and JNK, whose activation neutralized the improvement of puerarin on the secretory function and apoptosis of ovarian granulosa cells (GCs). Meanwhile, puerarin alleviated the accumulation of cytosolic Ca2+ through restricting the opening of Ryr and Itpr channels, but this effectiveness was counteracted by the activatory ERK1/2 and JNK. Attenuation of cytosolic Ca2+ counteracted the antagonistic effects of ERK1/2 and JNK activation on puerarin's role in rescuing the calcineurin and Nfatc. Further analysis manifested that Mcu had been authenticated as a direct downstream target of Nfatc to mediate the amelioration of puerarin on mitochondrial Ca2+ uptake. Moreover, puerarin prevented the disorder of ATP content, mitochondrial membrane potential, and mitochondrial permeability transition pore opening through maintaining mitochondrial Ca2+ homeostasis. Collectively, puerarin might ameliorate the symptoms of PCOS mice through preventing mitochondrial dysfunction that is dependent on the maintenance of intracellular Ca2+ homeostasis after inactivation of ERK1/2 and JNK.

Roles of ubiquitin-specific proteases in inflammatory diseases

Ubiquitin-specific proteases (USPs), as one of the deubiquitinating enzymes (DUBs) families, regulate the fate of proteins and signaling pathway transduction by removing ubiquitin chains from the target proteins. USPs are essential for the modulation of a variety of physiological processes, such as DNA repair, cell metabolism and differentiation, epigenetic modulations as well as protein stability. Recently, extensive research has demonstrated that USPs exert a significant impact on innate and adaptive immune reactions, metabolic syndromes, inflammatory disorders, and infection via post-translational modification processes. This review summarizes the important roles of the USPs in the onset and progression of inflammatory diseases, including periodontitis, pneumonia, atherosclerosis, inflammatory bowel disease, sepsis, hepatitis, diabetes, and obesity. Moreover, we highlight a comprehensive overview of the pathogenesis of USPs in these inflammatory diseases as well as post-translational modifications in the inflammatory responses and pave the way for future prospect of targeted therapies in these inflammatory diseases.

The prognostic value of whole-genome DNA methylation in response to Leflunomide in patients with Rheumatoid Arthritis

Objective

Although Leflunomide (LEF) is effective in treating rheumatoid arthritis (RA), there are still a considerable number of patients who respond poorly to LEF treatment. Till date, few LEF efficacy-predicting biomarkers have been identified. Herein, we explored and developed a DNA methylation-based predictive model for LEF-treated RA patient prognosis.

Methods

Two hundred forty-five RA patients were prospectively enrolled from four participating study centers. A whole-genome DNA methylation profiling was conducted to identify LEF-related response signatures via comparison of 40 samples using Illumina 850k methylation arrays. Furthermore, differentially methylated positions (DMPs) were validated in the 245 RA patients using a targeted bisulfite sequencing assay. Lastly, prognostic models were developed, which included clinical characteristics and DMPs scores, for the prediction of LEF treatment response using machine learning algorithms.

Results

We recognized a seven-DMP signature consisting of cg17330251, cg19814518, cg20124410, cg21109666, cg22572476, cg23403192, and cg24432675, which was effective in predicting RA patient's LEF response status. In the five machine learning algorithms, the support vector machine (SVM) algorithm provided the best predictive model, with the largest discriminative ability, accuracy, and stability. Lastly, the AUC of the complex model(the 7-DMP scores with the lymphocyte and the diagnostic age) was higher than the simple model (the seven-DMP signature, AUC:0.74 vs 0.73 in the test set).

Conclusion

In conclusion, we constructed a prognostic model integrating a 7-DMP scores with the clinical patient profile to predict responses to LEF treatment. Our model will be able to effectively guide clinicians in determining whether a patient is LEF treatment sensitive or not.

Goliath induces inflammation in obese mice by linking fatty acid β-oxidation to glycolysis

Obesity is associated with metabolic disorders and chronic inflammation. However, the obesity-associated metabolic contribution to inflammatory induction remains elusive. Here, we show that, compared with lean mice, CD4+ T cells from obese mice exhibit elevated basal levels of fatty acid β-oxidation (FAO), which promote T cell glycolysis and thus hyperactivation, leading to enhanced induction of inflammation. Mechanistically, the FAO rate-limiting enzyme carnitine palmitoyltransferase 1a (Cpt1a) stabilizes the mitochondrial E3 ubiquitin ligase Goliath, which mediates deubiquitination of calcineurin and thus enhances activation of NF-AT signaling, thereby promoting glycolysis and hyperactivation of CD4+ T cells in obesity. We also report the specific GOLIATH inhibitor DC-Gonib32, which blocks this FAO-glycolysis metabolic axis in CD4+ T cells of obese mice and reduces the induction of inflammation. Overall, these findings establish a role of a Goliath-bridged FAO-glycolysis axis in mediating CD4+ T cell hyperactivation and thus inflammation in obese mice.

Histone H2A deubiquitinases in the transcriptional programs of development and hematopoiesis: a consolidated analysis

Monoubiquitinated lysine 119 of histone H2A (H2AK119ub) is a highly abundant epigenetic mark, associated with gene repression and deposited on chromatin by the polycomb repressor complex 1 (PRC1), which is an essential regulator of diverse transcriptional programs in mammalian development and tissue homeostasis. While multiple deubiquitinases (DUBs) with catalytic activity for H2AK119ub (H2A-DUBs) have been identified, we lack systematic analyses of their roles and cross-talk in transcriptional regulation. Here, we address H2A-DUB functions in epigenetic regulation of mammalian development and tissue maintenance by conducting a meta-analysis of 248 genomics datasets from 32 independent studies, focusing on the mouse model and covering embryonic stem cells (ESCs), hematopoietic, and immune cell lineages. This covers all the publicly available datasets that map genomic H2A-DUB binding and H2AK119ub distributions (ChIP-Seq), and all datasets assessing dysregulation in gene expression in the relevant H2A-DUB knockout models (RNA-Seq). Many accessory datasets for PRC1-2 and DUB-interacting proteins are also analyzed and interpreted, as well as further data assessing chromatin accessibility (ATAC-Seq) and transcriptional activity (RNA-seq). We report co-localization in the binding of H2A-DUBs BAP1, USP16, and to a lesser extent others that is conserved across different cell-types, and also the enrichment of antagonistic PRC1-2 protein complexes at the same genomic locations. Such conserved sites enriched for the H2A-DUBs and PRC1-2 are proximal to transcriptionally active genes that engage in housekeeping cellular functions. Nevertheless, they exhibit H2AK119ub levels significantly above the genomic average that can undergo further increase with H2A-DUB knockout. This indicates a cooperation between H2A-DUBs and PRC1-2 in the modulation of housekeeping transcriptional programs, conserved across many cell types, likely operating through their antagonistic effects on H2AK119ub and the regulation of local H2AK119ub turnover. Our study further highlights existing knowledge gaps and discusses important directions for future work.

TRABID overexpression enables synthetic lethality to PARP inhibitor via prolonging 53BP1 retention at double-strand breaks

53BP1 promotes nonhomologous end joining (NHEJ) over homologous recombination (HR) repair by mediating inactivation of DNA end resection. Ubiquitination plays an important role in regulating dissociation of 53BP1 from DNA double-strand breaks (DSBs). However, how this process is regulated remains poorly understood. Here, we demonstrate that TRABID deubiquitinase binds to 53BP1 at endogenous level and regulates 53BP1 retention at DSB sites. TRABID deubiquitinates K29-linked polyubiquitination of 53BP1 mediated by E3 ubiquitin ligase SPOP and prevents 53BP1 dissociation from DSBs, consequently inducing HR defects and chromosomal instability. Prostate cancer cells with TRABID overexpression exhibit a high sensitivity to poly (ADP-ribose) polymerase (PARP) inhibitors. Our work shows that TRABID facilitates NHEJ repair over HR during DNA repair by inducing prolonged 53BP1 retention at DSB sites, suggesting that TRABID overexpression may predict HR deficiency and the potential therapeutic use of PARP inhibitors in prostate cancer.

The Pleiotropic Ubiquitin-Specific Peptidase 16 and Its Many Substrates

Ubiquitin-specific peptidase 16 (USP16) is a deubiquitinase that plays a role in the regulation of gene expression, cell cycle progression, and various other functions. It was originally identified as the major deubiquitinase for histone H2A and has since been found to deubiquitinate a range of other substrates, including proteins from both the cytoplasm and nucleus. USP16 is phosphorylated when cells enter mitosis and dephosphorylated during the metaphase/anaphase transition. While much of USP16 is localized in the cytoplasm, separating the enzyme from its substrates is considered an important regulatory mechanism. Some of the functions that USP16 has been linked to include DNA damage repair, immune disease, tumorigenesis, protein synthesis, coronary artery health, and male infertility. The strong connection to immune response and the fact that multiple oncogene products are substrates of USP16 suggests that USP16 may be a potential therapeutic target for the treatment of certain human diseases.

Hypothalamic transcriptome analysis reveals male-specific differences in molecular pathways related to oxidative phosphorylation between Iberian pig genotypes

The hypothalamus is implicated in controlling feeding and adiposity, besides many other physiological functions, and thus can be of great importance in explaining productive differences between lean and fatty pig breeds. The present study aimed to evaluate the hypothalamic transcriptome of pure Iberian (IBxIB) and Large White x Iberian crossbreds (IBxLW) at 60 days-old, produced in a single maternal environment. Results showed the implication of gender and genotype in the hypothalamic transcriptome, with 51 differentially expressed genes (DEGs) between genotypes and 10 DEGs between genders. Fourteen genotype by sex interactions were found, due to a higher genotype effect on transcriptome found in males. In fact, just 31 DEGs were identified when using only females but 158 using only males. A higher expression of genes related to mitochondrial activity in IBxIB male animals (ND3, ND4, ND5, UQCRC2 and ATP6) was found, which was related to a higher oxidative phosphorylation and greater reactive oxygen species and nitric oxide production. IBxLW male animals showed higher expression of SIRT3 regulator, also related to mitochondrial function. When females were analysed, such differences were not found, since only some differences in genes related to the tricarboxylic acid cycle. Thus, the results indicate a significant effect and interaction of the breed and the sex on the hypothalamic transcriptome at this early age.

USP16-mediated histone H2A lysine-119 deubiquitination during oocyte maturation is a prerequisite for zygotic genome activation

Maternal-to-zygotic transition (MZT) is the first and key step in the control of animal development and intimately related to changes in chromatin structure and histone modifications. H2AK119ub1, an important epigenetic modification in regulating chromatin configuration and function, is primarily catalyzed by PRC1 and contributes to resistance to transcriptional reprogramming in mouse embryos. In this study, the genome-wide dynamic distribution of H2AK119ub1 during MZT in mice was investigated using chromosome immunoprecipitation and sequencing. The results indicated that H2AK119ub1 accumulated in fully grown oocytes and was enriched at the TSSs of maternal genes, but was promptly declined after meiotic resumption at genome-wide including the TSSs of early zygotic genes, by a previously unidentified mechanism. Genetic evidences indicated that ubiquitin-specific peptidase 16 (USP16) is the major deubiquitinase for H2AK119ub1 in mouse oocytes. Conditional knockout of Usp16 in oocytes did not impair their survival, growth, or meiotic maturation. However, oocytes lacking USP16 have defects when undergoing zygotic genome activation or gaining developmental competence after fertilization, potentially associated with high levels of maternal H2AK119ub1 deposition on the zygotic genomes. Taken together, H2AK119ub1 level is declined during oocyte maturation by an USP16-dependent mechanism, which ensures zygotic genome reprogramming and transcriptional activation of essential early zygotic genes.

Exploiting the ubiquitin system in myeloid malignancies. From basic research to drug discovery in MDS and AML

The ubiquitin-proteasome system is the crucial homeostatic mechanism responsible for the degradation and turnover of proteins. As such, alterations at this level are often associated with oncogenic processes, either through accumulation of undegraded pathway effectors or, conversely, excessive degradation of tumor-suppressing factors. Therefore, investigation of the ubiquitin- proteasome system has gained much attraction in recent years, especially in the context of hematological malignancies, giving rise to efficient therapeutics such as bortezomib for multiple myeloma. Current investigations are now focused on manipulating protein degradation via fine-tuning of the ubiquitination process through inhibition of deubiquitinating enzymes or development of PROTAC systems for stimulation of ubiquitination and protein degradation. On the other hand, the efficiency of Thalidomide derivates in myelodysplastic syndromes (MDS), such as Lenalidomide, acted as the starting point for the development of targeted leukemia-associated protein degradation molecules. These novel molecules display high efficiency in overcoming the limitations of current therapeutic regimens, such as refractory diseases. Therefore, in this manuscript we will address the therapeutic opportunities and strategies based on the ubiquitin-proteasome system, ranging from the modulation of deubiquitinating enzymes and, conversely, describing the potential of modern targeted protein degrading molecules and their progress into clinical implementation.

Brain Epitranscriptomic Analysis Revealed Altered A-to-I RNA Editing in Septic Patients

Recent studies suggest that RNA editing is associated with impaired brain function and neurological and psychiatric disorders. However, the role of A-to-I RNA editing during sepsis-associated encephalopathy (SAE) remains unclear. In this study, we analyzed adenosine-to-inosine (A-to-I) RNA editing in postmortem brain tissues from septic patients and controls. A total of 3024 high-confidence A-to-I RNA editing sites were identified. In sepsis, there were fewer A-to-I RNA editing genes and editing sites than in controls. Among all A-to-I RNA editing sites, 42 genes showed significantly differential RNA editing, with 23 downregulated and 19 upregulated in sepsis compared to controls. Notably, more than 50% of these genes were highly expressed in the brain and potentially related to neurological diseases. Notably, cis-regulatory analysis showed that the level of RNA editing in six differentially edited genes was significantly correlated with the gene expression, including HAUS augmin-like complex subunit 2 (HAUS2), protein phosphatase 3 catalytic subunit beta (PPP3CB), hook microtubule tethering protein 3 (HOOK3), CUB and Sushi multiple domains 1 (CSMD1), methyltransferase-like 7A (METTL7A), and kinesin light chain 2 (KLC2). Furthermore, enrichment analysis showed that fewer gene functions and KEGG pathways were enriched by edited genes in sepsis compared to controls. These results revealed alteration of A-to-I RNA editing in the human brain associated with sepsis, thus providing an important basis for understanding its role in neuropathology in SAE.

Yeast as a Model to Find New Drugs and Drug Targets for VPS13-Dependent Neurodegenerative Diseases

Mutations in human VPS13A-D genes result in rare neurological diseases, including chorea-acanthocytosis. The pathogenesis of these diseases is poorly understood, and no effective treatment is available. As VPS13 genes are evolutionarily conserved, the effects of the pathogenic mutations could be studied in model organisms, including yeast, where one VPS13 gene is present. In this review, we summarize advancements obtained using yeast. In recent studies, vps13Δ and vps13-I2749 yeast mutants, which are models of chorea-acanthocytosis, were used to screen for multicopy and chemical suppressors. Two of the suppressors, a fragment of the MYO3 and RCN2 genes, act by downregulating calcineurin activity. In addition, vps13Δ suppression was achieved by using calcineurin inhibitors. The other group of multicopy suppressors were genes: FET4, encoding iron transporter, and CTR1, CTR3 and CCC2, encoding copper transporters. Mechanisms of their suppression rely on causing an increase in the intracellular iron content. Moreover, among the identified chemical suppressors were copper ionophores, which require a functional iron uptake system for activity, and flavonoids, which bind iron. These findings point at areas for further investigation in a higher eukaryotic model of VPS13-related diseases and to new therapeutic targets: calcium signalling and copper and iron homeostasis. Furthermore, the identified drugs are interesting candidates for drug repurposing for these diseases.

Modulating the Ubiquitin–Proteasome System: A Therapeutic Strategy for Autoimmune Diseases

Multiple sclerosis (MS) is an autoimmune, neurodegenerative disease associated with the central nervous system (CNS). Autoimmunity is caused by an abnormal immune response to self-antigens, which results in chronic inflammation and tissue death. Ubiquitination is a post-translational modification in which ubiquitin molecules are attached to proteins by ubiquitinating enzymes, and then the modified proteins are degraded by the proteasome system. In addition to regulating proteasomal degradation of proteins, ubiquitination also regulates other cellular functions that are independent of proteasomal degradation. It plays a vital role in intracellular protein turnover and immune signaling and responses. The ubiquitin–proteasome system (UPS) is primarily responsible for the nonlysosomal proteolysis of intracellular proteins. The 26S proteasome is a multicatalytic adenosine-triphosphate-dependent protease that recognizes ubiquitin covalently attached to particular proteins and targets them for degradation. Damaged, oxidized, or misfolded proteins, as well as regulatory proteins that govern many essential cellular functions, are removed by this degradation pathway. When this system is affected, cellular homeostasis is altered, resulting in the induction of a range of diseases. This review discusses the biochemistry and molecular biology of the UPS, including its role in the development of MS and proteinopathies. Potential therapies and targets involving the UPS are also addressed.

New Insights into Epigenetic Regulation of T Cell Differentiation

Immature CD4⁻ CD8⁻ thymocytes progress through several developmental steps in the thymus, ultimately emerging as mature CD4⁺ (helper) or CD8⁺ (cytotoxic) T cells. Activation of naïve CD4⁺ and CD8⁺ T cells in the presence of specific cytokines results in the induction of transcriptional programs that result in their differentiation into effector or memory cells and in the case of CD4⁺ T cells, the adoption of distinct T-helper fates. Previous studies have shown that histone modification and DNA methylation play important roles in each of these events. More recently, the roles of specific epigenetic regulators in T cell differentiation have been clarified. The identification of the epigenetic modifications and modifiers that control mature T cell differentiation and specification has also provided further insights into how dysregulation of these processes can lead to cancer or autoimmune diseases. In this review, we summarize recent findings that have provided new insights into epigenetic regulation of T cell differentiation in both mice and humans.

Deubiquitylating enzymes: potential target in autoimmune diseases

The ubiquitin-proteasome pathway is responsible for the turnover of different cellular proteins, such as transport proteins, presentation of antigens to the immune system, control of the cell cycle, and activities that promote cancer. The enzymes which remove ubiquitin, deubiquitylating enzymes (DUBs), play a critical role in central and peripheral immune tolerance to prevent the development of autoimmune diseases and thus present a potential therapeutic target for the treatment of autoimmune diseases. DUBs function by removing ubiquitin(s) from target protein and block ubiquitin chain elongation. The addition and removal of ubiquitin molecules have a significant impact on immune responses. DUBs and E3 ligases both specifically cleave target protein and modulate protein activity and expression. The balance between ubiquitylation and deubiquitylation modulates protein levels and also protein interactions. Dysregulation of the ubiquitin-proteasome pathway results in the development of various autoimmune diseases such as inflammatory bowel diseases (IBD), psoriasis, multiple sclerosis (MS), systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). This review summarizes the current understanding of ubiquitination in autoimmune diseases and focuses on various DUBs responsible for the progression of autoimmune diseases.

Calcineurin in the heart: New horizons for an old friend

Calcineurin, also known as PP2B or PPP3, is a member of the PPP family of protein phosphatases that also includes PP1 and PP2A. Together these three phosphatases carryout the majority of dephosphorylation events in the heart. Calcineurin is distinct in that it is activated by the binding of calcium/calmodulin (Ca2+/CaM) and therefore acts as a node for integrating Ca2+ signals with changes in phosphorylation, two fundamental intracellular signaling cascades. In the heart, calcineurin is primarily thought of in the context of pathological cardiac remodeling, acting through the Nuclear Factor of Activated T-cell (NFAT) family of transcription factors. However, calcineurin activity is also essential for normal heart development and homeostasis in the adult heart. Furthermore, it is clear that NFAT-driven changes in transcription are not the only relevant processes initiated by calcineurin in the setting of pathological remodeling. There is a growing appreciation for the diversity of calcineurin substrates that can impact cardiac function as well as the diversity of mechanisms for targeting calcineurin to specific sub-cellular domains in cardiomyocytes and other cardiac cell types. Here, we will review the basics of calcineurin structure, regulation, and function in the context of cardiac biology. Particular attention will be given to: the development of improved tools to identify and validate new calcineurin substrates; recent studies identifying new calcineurin isoforms with unique properties and targeting mechanisms; and the role of calcineurin in cardiac development and regeneration.

Homozygosity Haplotype and Whole-Exome Sequencing Analysis to Identify Potentially Functional Rare Variants Involved in Multiple Sclerosis among Sardinian Families

Multiple Sclerosis (MS) is a complex multifactorial autoimmune disease, whose sex- and age-adjusted prevalence in Sardinia (Italy) is among the highest worldwide. To date, 233 loci were associated with MS and almost 20% of risk heritability is attributable to common genetic variants, but many low-frequency and rare variants remain to be discovered. Here, we aimed to contribute to the understanding of the genetic basis of MS by investigating potentially functional rare variants. To this end, we analyzed thirteen multiplex Sardinian families with Immunochip genotyping data. For five families, Whole Exome Sequencing (WES) data were also available. Firstly, we performed a non-parametric Homozygosity Haplotype analysis for identifying the Region from Common Ancestor (RCA). Then, on these potential disease-linked RCA, we searched for the presence of rare variants shared by the affected individuals by analyzing WES data. We found: (i) a variant (43181034 T > G) in the splicing region on exon 27 of CUL9; (ii) a variant (50245517 A > C) in the splicing region on exon 16 of ATP9A; (iii) a non-synonymous variant (43223539 A > C), on exon 9 of TTBK1; (iv) a non-synonymous variant (42976917 A > C) on exon 9 of PPP2R5D; and v) a variant (109859349-109859354) in 3'UTR of MYO16.

The deubiquitinase USP16 functions as an oncogenic factor in K-RAS-driven lung tumorigenesis

K-RAS mutation and molecular alterations of its surrogates function essentially in lung tumorigenesis and malignant progression. However, it remains elusive how tumor-promoting and deleterious events downstream of K-RAS signaling are coordinated in lung tumorigenesis. Here, we show that USP16, a deubiquitinase involved in various biological processes, functions as a promoter for the development of K-RAS-driven lung tumor. Usp16 deletion significantly attenuates K-rasG12D-mutation-induced lung tumorigenesis in mice. USP16 upregulation upon RAS activation averts reactive oxygen species (ROS)-induced p38 activation that would otherwise detrimentally influence the survival and proliferation of tumor cells. In addition, USP16 interacts with and deubiquitinates JAK1, and thereby promoting lung tumor growth by augmenting JAK1 signaling. Therefore, our results reveal that USP16 functions critically in the K-RAS-driven lung tumorigenesis through modulating the strength of p38 and JAK1 signaling.

Paraquat but not diquat induces TGF-β expression and thus activates calcium-NFAT axis for epithelial-mesenchymal transition

Paraquat (PQ) and diquat (DQ), two highly efficient herbicides sharing similar chemical backbone, both induce reactive oxygen species and are highly toxic to humans and livestock, however, PQ but not DQ poisoning result in pulmonary fibrosis, the leading cause of high mortality rate in patients suffering PQ toxicity. Understanding the unique mechanism of PQ different from DQ therefore would provide potential strategies to reduce PQ-induced pulmonary fibrosis. Here, we identified that PQ but not DQ continuously upregulates TGF-β expression in alveolar type II (AT II) cells. Importantly, such high expression of TGF-β increases cytosolic calcium levels and further promotes the activation of calcineurin-NFAT axis. TGF-β mainly activates NFATc1 and NFATc2, but not NFATc3 or NFATc4. Administration of the inhibitors targeting cytosolic calcium or calcineurin largely reverses PQ-induced epithelial-mesenchymal transition (EMT), whereas DQ has little effects on activation of NFAT and EMT. Ultimately, PQ poisoned patients exhibit significantly reduced blood calcium levels compared to DQ poisoning, possibly via the large usage of calcium by AT II cells. All in all, we found a vicious cycle that the upregulated TGF-β in PQ-induced EMT further aggravates EMT via promotion of the calcium-calcineurin axis, which could be potential drug targets for treating PQ-induced pulmonary fibrosis.

The Route of Early T Cell Development: Crosstalk between Epigenetic and Transcription Factors

Hematopoietic multipotent progenitors seed the thymus and then follow consecutive developmental stages until the formation of mature T cells. During this process, phenotypic changes of T cells entail stage-specific transcriptional programs that underlie the dynamic progression towards mature lymphocytes. Lineage-specific transcription factors are key drivers of T cell specification and act in conjunction with epigenetic regulators that have also been elucidated as crucial players in the establishment of regulatory networks necessary for proper T cell development. In this review, we summarize the activity of transcription factors and epigenetic regulators that together orchestrate the intricacies of early T cell development with a focus on regulation of T cell lineage commitment.

The ubiquitin ligase Peli1 inhibits ICOS and thereby Tfh-mediated immunity

T follicular helper (Tfh) cells are crucial for regulating autoimmune inflammation and protective immunity against viral infection. However, the molecular mechanism controlling Tfh cell differentiation is poorly understood. Here, through two mixed bone marrow chimeric experiments, we identified Peli1, a T cell-enriched E3 ubiquitin ligase, as an intrinsic regulator that inhibits Tfh cell differentiation. Peli1 deficiency significantly promoted c-Rel-mediated inducible T-cell costimulator (ICOS) expression, and PELI1 mRNA expression was negatively associated with ICOS expression on human CD4⁺ T cells. Mechanistically, increased ICOS expression on Peli1-KO CD4⁺ T cells enhanced the activation of PI3K-AKT signaling and thus suppressed the expression of Klf2, a transcription factor that inhibits Tfh differentiation. Therefore, reconstitution of Klf2 abolished the differences in Tfh differentiation and germinal center reaction between WT and Peli1-KO cells. As a consequence, Peli1-deficient CD4⁺ T cells promoted lupus-like autoimmunity but protected against H1N1 influenza virus infection in mouse models. Collectively, our findings established Peli1 as a critical negative regulator of Tfh differentiation and indicated that targeting Peli1 may have beneficial therapeutic effects in Tfh-related autoimmunity or infectious diseases.

TRIM24 facilitates antiviral immunity through mediating K63-linked TRAF3 ubiquitination

Ubiquitination is an essential mechanism in the control of antiviral immunity upon virus infection. Here, we identify a series of ubiquitination-modulating enzymes that are modulated by vesicular stomatitis virus (VSV). Notably, TRIM24 is down-regulated through direct transcriptional suppression induced by VSV-activated IRF3. Reducing or ablating TRIM24 compromises type I IFN (IFN-I) induction upon RNA virus infection and thus renders mice more sensitive to VSV infection. Mechanistically, VSV infection induces abundant TRIM24 translocation to mitochondria, where TRIM24 binds with TRAF3 and directly mediates K63-linked TRAF3 ubiquitination at K429/K436. This modification of TRAF3 enables its association with MAVS and TBK1, which consequently activates downstream antiviral signaling. Together, these findings establish TRIM24 as a critical positive regulator in controlling the activation of antiviral signaling and describe a previously unknown mechanism of TRIM24 function.

Partial Inhibition of Calcineurin Activity by Rcn2 as a Potential Remedy for Vps13 Deficiency

Regulation of calcineurin, a Ca²⁺/calmodulin-regulated phosphatase, is important for the nervous system, and its abnormal activity is associated with various pathologies, including neurodegenerative disorders. In yeast cells lacking the VPS13 gene (vps13Δ), a model of VPS13-linked neurological diseases, we recently demonstrated that calcineurin is activated, and its downregulation reduces the negative effects associated with vps13Δ mutation. Here, we show that overexpression of the RCN2 gene, which encodes a negative regulator of calcineurin, is beneficial for vps13Δ cells. We studied the molecular mechanism underlying this effect through site-directed mutagenesis of RCN2. The interaction of the resulting Rcn2 variants with a MAPK kinase, Slt2, and subunits of calcineurin was tested. We show that Rcn2 binds preferentially to Cmp2, one of two alternative catalytic subunits of calcineurin, and partially inhibits calcineurin. Rcn2 ability to bind to and reduce the activity of calcineurin was important for the suppression. The binding of Rcn2 to Cmp2 requires two motifs in Rcn2: the previously characterized C-terminal motif and a new N-terminal motif that was discovered in this study. Altogether, our findings can help to better understand calcineurin regulation and to develop new therapeutic strategies against neurodegenerative diseases based on modulation of the activity of selected calcineurin isoforms.

Substrate-specific recognition of IKKs mediated by USP16 facilitates autoimmune inflammation

The classic NF-κB pathway plays crucial roles in various immune responses and inflammatory diseases. Its key kinase, IKKβ, participates in a variety of pathological and physiological processes by selectively recognizing its downstream substrates, including p105, p65, and IκBα, but the specific mechanisms of these substrates are unclear. Hyperactivation of one of the substrates, p105, is closely related to the onset of inflammatory bowel disease (IBD) in Nfkb1-deficient mice. In this study, we found that IKKβ ubiquitination on lysine-238 was substantially increased during inflammation. Using mass spectrometry, we identified USP16 as an essential regulator of the IKKβ ubiquitination level that selectively affected p105 phosphorylation without directly affecting p65 or IκBα phosphorylation. Furthermore, USP16 was highly expressed in colon macrophages in patients with IBD, and myeloid-conditional USP16-knockout mice exhibited reduced IBD severity. Our study provides a new theoretical basis for IBD pathogenesis and targeted precision intervention therapy.

Nanomedicine-mediated induction of immunogenic cell death and prevention of PD-L1 overexpression for enhanced hepatocellular carcinoma therapy

Background

The present study aims to develop a nanoparticle encapsulating doxorubicin (DOX) and programmed death-ligand 1 (PD-L1) siRNA and evaluate its anti-tumor effects on hepatoma carcinoma (HCC).

Methods

Nanoparticle encapsulating DOX and PD-L1 siRNA (NPDOX/siPD-L1) was characterized by dynamic light scattering and transmission electron microscopy. Flow cytometry was applied to analyze cell populations, NPDOX/siPD-L1 internalization, and cell apoptosis. Real-Time (RT)-quantitative reverse transcription (qPCR) and western blotting were used to determine the mRNA and protein levels, respectively. Released ATP was determined using ATP determination kit and cytokines were determined using specific ELISAs. A tumor-bearing animal model was established to evaluate the anti-tumor effects of NPDOX/siPD-L1.

Results

Treatment of NPDOX/siPD-L1 induced immunogenic cell death (ICD) and PD-L1 overexpression in HCC. In vivo study demonstrated that intravenously injection of NPDOX/siPD-L1 significantly inhibited the tumor volume and PD-L1 expressions of tumor tissue in the H22 tumor-bearing animal model. Besides, the treatment of NPDOX/siPD-L1 also regulated the populations of matured dendritic cells and cytotoxic T cells and the productions of cytokines in the tumor tissues.

Conclusion

Taken together, NPDOX/siPD-L1 showed significant anti-tumor effects on HCC by the induction of ICD and inhibition of PD-L1 overexpression.

Role of Epigenetics in the Regulation of Immune Functions of the Skin

This review is intended to illuminate the emerging understanding of epigenetic modifications that regulate both adaptive and innate immunity in the skin. Host defense of the epidermis and dermis involves the interplay of many cell types to enable homeostasis; tolerance to the external environment; and appropriate response to transient microbial, chemical, and physical insults. To understand this process, the study of cutaneous immunology has focused on immune responses that reflect both adaptive learned and genetically programmed innate defense systems. However, recent advances have begun to reveal that epigenetic modifications of chromatin structure also have a major influence on the skin immune system. This deeper understanding of how enzymatic changes in chromatin structure can modify the skin immune system and may explain how environmental exposures during life, and the microbiome, lead to both short-term and long-term changes in cutaneous allergic and other inflammatory processes. Understanding the mechanisms responsible for alterations in gene and chromatin structure within skin immunocytes could provide key insights into the pathogenesis of inflammatory skin diseases that have thus far evaded understanding by dermatologists.

Extracellular Vesicles Derived from Human Umbilical Cord Mesenchymal Stem Cells Protect Liver Ischemia/Reperfusion Injury by Reducing CD154 Expression on CD4+ T Cells via CCT2

As a cause of postoperative complications and early hepatic failure after liver transplantation, liver ischemia/reperfusion injury (IRI) still has no effective treatment during clinical administration. Although the therapeutic potential of mesenchymal stem cells (MSCs) for liver IRI has been previously shown, the underlying mechanisms are not completely clear. It is accepted that MSC-derived extracellular vesicles (MSC-EVs) are newly uncovered messengers for intercellular communication. Herein, it is reported that umbilical cord-derived MSCs (UC-MSCs) improve liver IRI in mice through their secreted EVs. It is also visualized that UC-MSC-EVs mainly concentrate in liver after 6 h of reperfusion. Furthermore, UC-MSC-EVs are found to significantly modulate the membranous expression of CD154 of intrahepatic CD4+ T cells, which is an initiation of inflammatory response in liver and can aggravate liver IRI. Mechanistically, protein mass spectrum analysis is performed and it is revealed that Chaperonin containing TCP1 subunit 2 (CCT2) enriches in UC-MSC-EVs, which regulates the calcium channels to affect Ca2+ influx and suppress CD154 synthesis in CD4+ T cells. In conclusion, these results highlight the therapeutic potential of UC-MSC-EVs in attenuating liver IRI. This finding suggests that CCT2 from UC-MSC-EVs can modulate CD154 expression of intrahepatic CD4+ T cells during liver IRI through the Ca2+-calcineurin-NFAT1 signaling pathway.

Copy number variation of the USP16 gene and its association with milk traits in Chinese Holstein cattle

Copy number variations (CNVs) were similar to single nucleotide polymorphisms (SNPs) and insertion-deletion (InDel), regarded as genetic variations in many species. CNV is defined as the variable change of DNA segment length compared with the reference genome, including gains or losses from 50 bp to several mega bases. The functions of USP16 gene are diverse, such as regulating the cell cycle, DNA damage, histone H2A deubiquitination or mitotic nuclear division. To analyze the relationship between CNV of USP16 gene and milk traits in Chinese Holstein, we used qPCR to detect the individuals of Chinese Holstein (n = 180). The results showed that the effect of USP16 gene CNV on daily milk yield and fat percentage had significant difference (p < 0.05). The gain was the advantage type in daily milk yield and the loss was the advantage type in fat percentage. Therefore, CNV of USP16 gene is an important factor of milk traits in Chinese Holstein. Meanwhile, it may be used as a molecular marker for assisted selection of milk traits in Chinese Holstein, which provides a theoretical basis for the genetic improvement of cow breeds in China.

HIF1α Deficiency in Dendritic Cells Attenuates Symptoms and Inflammatory Indicators of Allergic Rhinitis in a SIRT1-Dependent Manner

BACKGROUND

Allergic rhinitis is the most prevalent atopic disorder worldwide. Inflammation is believed to participate in allergic rhinitis. Previous studies indicate that hypoxia-inducible factor (HIF) promotes the development of allergic rhinitis, and dendritic cells are also involved in allergic rhinitis.

METHODS

We explored the consequences of HIF1α deficiency in dendritic cells on allergic rhinitis. Allergic rhinitis in mice was induced by ovalbumin (OVA). The levels of IgE, leukotriene C4 (LTC4), eosinophil cationic protein (ECP), prostaglandin D2 (PGD2), IFN-γ, IL-2, IL-4, IL-5, IL-10, and IL-13 in serum or nasal lavage fluid (NLF) were detected by ELISA. Inflammatory cells in NLF were counted by hemocytometer. The protein levels of p-ERK1/2, p-p38, p-JNK2, SIRT1, p-IκBα, and p65 were determined by Western blot.

RESULTS

HIF1α deficiency in dendritic cells (HIF1αCD11c-/-) decreased sneezing and nasal rubbing, the production of OVA-specific IgE, LTC4, and ECP in serum and NLF, and the numbers of leukocytes, eosinophils, lymphocytes, and neutrophils in NLF. Th1 cytokines increased, while Th2 cytokines decreased in HIF1aCD11c-/- mice. SIRT1/NF-κB signaling was inhibited in HIF1αCD11c-/- mice, while SIRT1 inhibitor administration in HIF1αCD11c-/- mice attenuated the symptoms and inflammatory indicators of allergic rhinitis.

CONCLUSION

HIF1α deficiency in dendritic cells attenuates symptoms and inflammatory indicators of allergic rhinitis in a SIRT1-dependent manner.

Nanomedicine-mediated prevention of inflammatory monocytes infiltration ameliorate ovalbumin-induced allergic rhinitis in mouse model

Th2 immune cells infiltration into nasal mucosa is one of the characters of allergic rhinitis (AR). We aimed to explore whether inhibition of Th2 immune cells infiltration would attenuate AR progression. AR mouse model was established by i.p. injection of ovalbumin (OVA). The infiltrated immune cells into nasal lavage fluid were detected by flow cytometry. Cytokine concentration in serum was determined by ELISA. AR mice symptoms were indicated by the number of sneezing and nasal rubbing events. In AR mice, CCL2 expression levels and CD45⁺CD11b⁺Ly6C^hi inflammatory monocytes cells significantly increased as compared with control mice. CCL2 siRNA encapsulated nanoparticles (NP_siCCL2) prevent CCL2 expression and inflammatory monocytes infiltration in AR mice. NP_siCCL2 treatment dramatically decreased the number of sneezing and nasal rubbing events in AR mice. Moreover, NP_siCCL2 treatment attenuated serum OVA-specific IgE, OVA-specific IgG1 and histamine levels. Mechanically, NP_siCCL2 treatment attenuates AR symptoms via inhibiting Th2 cytokine (IL-4, IL-5 and IL-13) production. Nanomedicine-mediated prevention of inflammatory monocytes infiltration ameliorates ovalbumin-induced allergic rhinitis in mouse model.

Deubiquitinating enzymes (DUBs): DoUBle-edged swords in CNS autoimmunity

Multiple sclerosis (MS) is the most common autoimmune disease of the CNS. The etiology of MS is still unclear but it is widely recognized that both genetic and environmental factors contribute to its pathogenesis. Immune signaling and responses are critically regulated by ubiquitination, a posttranslational modification that is promoted by ubiquitinating enzymes and inhibited by deubiquitinating enzymes (DUBs). Genome-wide association studies (GWASs) identified that polymorphisms in or in the vicinity of two human DUB genes TNFAIP3 and USP18 were associated with MS susceptibility. Studies with experimental autoimmune encephalomyelitis (EAE), an animal model of MS, have provided biological rationale for the correlation between these DUBs and MS. Additional studies have shown that other DUBs are also involved in EAE by controlling distinct cell populations. Therefore, DUBs are emerging as crucial regulators of MS/EAE and might become potential therapeutic targets for the clinical treatment of MS.

Correlation between miR-223 and IL-35 and their regulatory effect in children with allergic rhinitis

The relationship between microRNA (miR) and immune activity in allergic rhinitis (AR) remains unclear. 37 children with AR and 30 healthy children were enrolled to study the correlation of miR-223 and IL-35. There was a significant inverse correlation between plasma levels of IL-35 and serum eosinophil cationic protein (ECP) levels and eosinophils counts, while there was a positive correlation between serum miR-223 level and ECP levels and eosinophils counts. Besides, the serum levels of IL-35 or miR-223 were found to be negatively or positively correlated with TNSS respectively. The serum level of miR-223 was increased, while IL-35 level was decreased. Moreover, the expression of miRNA-223 was inversely correlated with expression of IL-35. Finally, the levels of miR-223 and IL-35 were related to Th1/Th2 cytokines, eosinophils count as well as the clinical severity. Our study suggests the potential of miR-223 and IL-35 as a molecular target for the treatment of AR.

Desloratadine Ameliorates Olfactory Disorder and Suppresses AMPA Receptor GluA1 Expression in Allergic Rhinitis Rat

Allergic rhinitis (AR) is an IgE-mediated inflammation which causes olfactory dysfunction. Antihistamines have been widely used to treat AR while few studies have investigated the effect of antihistamines on improving the sense of smell. In addition, the underlying mechanisms are not well elucidated. We established the ovalbumin (OVA)-induced allergic rhinitis rat model and administrated desloratadine to AR rats. The AR symptoms, serum level of OVA-specific IgE and IL-17, and expression of IL-4, IL-5 and IL-13 in nasal mucosa were measured. The olfactory dysfunction was monitored by buried food test and the expression of GluR1 was measured. Desloratadine treatment alleviated AR symptoms, decreased serum level of OVA-specific IgE and IL-17 in AR rats. Desloratadine decreased IL-4, IL-5, and IL-13 expression in nasal mucosa of AR rats. Desloratadine ameliorated olfactory dysfunction in AR rats and decreased GluR1 expression in AR rats. Desloratadine treatment alleviated AR symptoms and ameliorated olfactory dysfunction in AR rats. The expression of AMPA receptor subunit GluR1 in olfactory bulb was associated with olfactory disorder.

Chromatin-Modifying Enzymes in T Cell Development

T cell development involves stepwise progression through defined stages that give rise to multiple T cell subtypes, and this is accompanied by the establishment of stage-specific gene expression. Changes in chromatin accessibility and chromatin modifications accompany changes in gene expression during T cell development. Chromatin-modifying enzymes that add or reverse covalent modifications to DNA and histones have a critical role in the dynamic regulation of gene expression throughout T cell development. As each chromatin-modifying enzyme has multiple family members that are typically all coexpressed during T cell development, their function is sometimes revealed only when two related enzymes are concurrently deleted. This work has also revealed that the biological effects of these enzymes often involve regulation of a limited set of targets. The growing diversity in the types and sites of modification, as well as the potential for a single enzyme to catalyze multiple modifications, is also highlighted.

Bufotalin ameliorates experimental Sjögren's syndrome development by inhibiting Th17 generation

Chronic inflammatory autoimmune disease Sjögren's syndrome (SS) is characterized by the reduced secretion of exocrine glands, suggesting strategies targeting inflammation to be a potential option for SS therapy. Bufotalin, an active constituent of Bufadienolides, exerts potent antitumor effects with unknown effects on autoimmune diseases including SS. This study aims to investigate whether bufotalin possesses therapeutic potentials to SS and the underlying mechanisms. The experimental Sjögren's syndrome (ESS) murine model was constructed by SG-immunization and murine naïve CD4⁺ T cells were cultured under Th17 polarization conditions with or without low doses of bufotalin treatment. Saliva flow rate was measured, and flow cytometry was applied to analyze T cell subpopulations. ELISA was conducted to determine the levels of targeted inflammatory cytokines. Bufotalin-treated ESS mice showed higher saliva flow rates, lower serum levels of autoantibodies (anti-M3R and anti-SSA IgG), lower serum levels of pro-inflammatory cytokines, as well as lower Th17 cell population from spleens and cervical lymph nodes. Additionally, in vitro study showed that bufotalin inhibits Th17 polarization and secretion of cytokines IL-17 and IFN-γ. Bufotalin at a low dose significantly ameliorates ESS development, possibly via inhibiting pro-inflammatory Th17 population and secretion of inflammatory cytokines during ESS pathogenesis.