FOXO3 is involved in the tumor necrosis factor-driven inflammatory response in fibroblast-like synoviocytes

Protein phosphatase SCP4 regulates cartilage development and endochondral osteogenesis via FoxO3a dephosphorylation

The regulatory mechanisms involved in embryonic development are complex and yet remain unclear. SCP4 represents a novel nucleus-resident phosphatase identified in our previous study. The primary aim of this study was to elucidate the function of SCP4 in the progress of cartilage development and endochondral osteogenesis. SCP4-/- and SCP4Col2ER mice were constructed to assess differences in bone formation using whole skeleton staining. ABH/OG staining was used to compare chondrocyte differentiation and cartilage development. Relevant biological functions were analysed using RNA-sequencing and GO enrichment, further validated by immunohistochemical staining, Co-IP and Western Blot. Global SCP4 knockout led to abnormal embryonic development in SCP4-/- mice, along with delayed endochondral osteogenesis. In parallel, chondrocyte-specific removal of SCP4 yielded more severe embryonic deformities in SCP4Col2ER mice, including limb shortening, reduced chondrocyte number in the growth plate, disorganisation and cell enlargement. Moreover, RNA-sequencing analysis showed an association between SCP4 and chondrocyte apoptosis. Notably, Tunnel-positive cells were indeed increased in the growth plates of SCP4Col2ER mice. The deficiency of SCP4 up-regulated the expression levels of pro-apoptotic proteins both in vivo and in vitro. Additionally, phosphorylation of FoxO3a (pFoxO3a), a substrate of SCP4, was heightened in chondrocytes of SCP4Col2ER mice growth plate, and the direct interaction between SCP4 and pFoxO3a was further validated in chondrocytes. Our findings underscore the critical role of SCP4 in regulating cartilage development and endochondral osteogenesis during embryonic development partially via inhibition of chondrocytes apoptosis regulated by FoxO3a dephosphorylation.

PIK3IP1: structure, aberration, function, and regulation in diseases

Phosphoinositide 3-kinase (PI3K) pathway, controlling diverse functions in cells, is one of the most frequently dysregulated pathways in cancer. Several negative regulators have been reported to intricately constrain the overactivation of PI3K pathway. Phosphatidylinoinosidine-3-kinase interacting protein 1 (PIK3IP1), as a unique transmembrane protein, is a newly discovered negative regulator of PI3K pathway. PIK3IP1 negatively regulates PI3K activity by directly binding to the p110 catalytic subunit of PI3K. It has been reported that PIK3IP1 is frequently low expressed in tumors and autoimmune diseases. In tumor cells and impaired cardiomyocyte, PIK3IP1 inhibits cell proliferation and survival. Consistently, the expression of PIK3IP1 is related with the condition of cancer. In addition, PIK3IP1 inhibits the inflammatory response and immune function via maintaining the quiescent state of immune cells. Thus, low expression of PIK3IP1 represents the severe condition of autoimmune diseases. PIK3IP1 is regulated by transcription factors, epigenetic factors or micro-RNAs to facilitate its normal function in different cellular contexts. This review integrates the total findings on PIK3IP1 in different disease, and summaries the structure, biological functions and regulatory mechanisms of PIK3IP1.

Interferon-Alpha Induces Psoriatic Inflammation in Mice by Phosphorylating FOXO3

Psoriasis is a chronic, immune-mediated inflammatory skin disease characterized by epidermal thickening and inflammatory cell infiltration. Excessive proliferation of keratinocytes and resistance to apoptosis lead to thickening of the epidermis. Plasmacytoid dendritic cells are involved in the occurrence of psoriasis mainly by secreting interferon-alpha (IFN-α). IFN-α is a glycoprotein with antiviral, antitumor, and immunomodulatory effects, but its role in psoriasis remains unclear. In this investigation, a mild psoriatic phenotype was observed in mice upon topical application of IFN-α cream, and the inflammation was exacerbated when combined with imiquimod (IMQ). Immunohistochemical analyses demonstrated that IFN-α induces psoriatic inflammation in mice by stimulating phosphorylation of forkhead box O3, consistent with the involvement of this protein in cell proliferation, apoptosis, and inflammation. Our results suggested that topical IFN-α caused psoriatic inflammation and that the psoriatic inflammation was exacerbated by the combination of IFN-α and IMQ, possibly due to the dysfunction of forkhead box O3.

Bioinformatics Analysis and Experimental Validation of Mitochondrial Autophagy Genes in Knee Osteoarthritis

Background

Mitochondrial autophagy is closely related to the pathogenesis of osteoarthritis, In order to explore the role of mitochondrial autophagy related genes in knee osteoarthritis (KOA) and its molecular mechanism.

Methods

KOA-related transcriptome data were extracted from the Gene Expression Omnibus (GEO) database. Differentially expressed mitochondrial autophagy gene (DEMGs) were screened in patients with KOA by differential expression analysis. The STRING website was used to construct a protein-protein interaction (PPI) network among DEMGs. Molecular complex detection (MCODE) method in Cytoscape software was performed to identify hub DEMGs. Support vector machine recursive feature elimination (SVM-RFE) method was used to construct the hub DEMG diagnosis model. Genes with diagnostic value were identified as biomarkers by plotting receiver operating characteristic (ROC) curves and Expression validation. CIBERSORT algorithm was used to calculate the proportion of 22 immune cells in each sample in the GSE114007 dataset. Finally, biomarker expression was verified by qPCR.

Results

A total of 15 DEMGs were obtained and enrichment analyses showed that these DEMG strains were mainly enriched in the mitophagy-animal, shigellosis, autophagy-animal and FoxO signal pathways. The PPI network unveiled 13 DEMGs with interactions. In addition, 8 hub DEMGs (ULK1, CALCOCO2, MAP1LC3B, BNIP3L, GABARAPL1, BNIP3, FKBP8 and FOXO3) were obtained for KOA. And 5 model DEMGs (BNIP3L, BNIP3, MAP1LC3B, ULK1 and FOXO3) were screened. The ROC curves revealed that BNIP3 and FOXO3 has strong diagnostic value in these models of DEMG. Immune-infiltration and correlation analysis showed that BNIP3 and FOXO3 were significantly correlated with three different immune cells, including primary B cells, M0 macrophage and M2 macrophage. The cartilage tissue samples qPCR verification results show that FOXO3 and BNIP3 were all down-regulated in KOA (p < 0.01), and the validation results are consistent with the above analysis.

Conclusion

BNIP3 and FOXO3 have been identified as biomarkers for the diagnosis of KOA, which might supply a new insight for the pathogenesis and treatment of KOA.

Screening crucial lncRNAs and genes in osteoarthritis by integrated analysis

BACKGROUND

Osteoarthritis (OA) is one of the most frequent chronic diseases with high morbidity worldwide, marked by degradation of the cartilage and bone, joint instability, stiffness, joint space stenosis and subchondral sclerosis. Due to the elusive mechanism of osteoarthritis (OA), we aimed to identify potential markers for OA and explore the molecular mechanisms underlying OA.

METHODS

Expression profiles data of OA were collected from the Gene Expression Omnibus database to identify differentially expressed mRNAs (DEmRNAs) and differentially expressed lncRNAs (DElncRNAs) in OA. Functional annotation and protein-protein interaction (PPI) networks were performed. Then, nearby DEmRNAs of DElncRNAs was obtained. Moreover, GO and KEGG pathway enrichment analysis of nearby DEmRNAs of DElncRNAs was performed. Finally, expression validation of selected mRNAs and lncRNAs was performed by quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

In total, 2080 DEmRNAs and 664 DElncRNAs were determined in OA. PI3K-Akt signaling pathway, Endocytosis and Rap1 signaling pathway were significantly enriched KEGG pathways in OA. YWHAB, HSPA8, NEDD4L and SH3KBP1 were four hub proteins in PPI network. The AC093484.4/TRPV2 interact pair may be involved in the occurrence and development of OA.

CONCLUSION

Our study identified several DEmRNAs and DElncRNAs associated with OA. The molecular characters could provide more information for further study on OA.

Berberine inhibits RA-FLS cell proliferation and adhesion by regulating RAS/MAPK/FOXO/HIF-1 signal pathway in the treatment of rheumatoid arthritis

AIMS

Rheumatoid arthritis (RA) is a common chronic immune disease. Berberine, as its main active ingredient, was also contained in a variety of medicinal plants such as Berberaceae, Buttercup, and Rutaceae, which are widely used in digestive system diseases in traditional Chinese medicine with anti-inflammatory and antibacterial effects. The aims of this article were to explore the therapeutic effect and mechanism of berberine on rheumatoid arthritis.

METHODS

Cell Counting Kit-8 was used to evaluate the effect of berberine on the proliferation of RA fibroblast-like synoviocyte (RA-FLS) cells. The effect of berberine on matrix metalloproteinase (MMP)-1, MMP-3, receptor activator of nuclear factor kappa-Β ligand (RANKL), tumour necrosis factor alpha (TNF-α), and other factors was determined by enzyme-linked immunoassay (ELISA) kit. Transcriptome technology was used to screen related pathways and the potential targets after berberine treatment, which were verified by reverse transcription-polymerase chain reaction (RT-qPCR) and Western blot (WB) technology.

RESULTS

Berberine inhibited proliferation and adhesion of RA-FLS cells, and significantly reduced the expression of MMP-1, MMP-3, RANKL, and TNF-α. Transcriptional results suggested that berberine intervention mainly regulated forkhead box O (FOXO) signal pathway, prolactin signal pathway, neurotrophic factor signal pathway, and hypoxia-inducible factor 1 (HIF-1) signal pathway.

CONCLUSION

The effect of berberine on RA was related to the regulation of RAS/mitogen-activated protein kinase/FOXO/HIF-1 signal pathway in RA-FLS cells.Cite this article: Bone Joint Res 2023;12(2):91-102.

Circular RNA circ_0130438 suppresses TNF-α-induced proliferation, migration, invasion and inflammation in human fibroblast-like MH7A synoviocytes by regulating miR-130a-3p/KLF9 axis

BACKGROUND

Circular RNAs (circRNAs) can play a critical role in rheumatoid arthritis (RA) pathogenesis by involving gene regulation by competing for shared microRNAs (miRNAs), a family of small noncoding RNAs. MiR-130a-3p is a disease-related miRNA and Kruppel-like factor 9 (KLF9) is a zinc finger transcription factor, which are involved in RA pathogenesis. Here, we identified the action of circRNA circ_0130438 in regulating fibroblast-like synoviocytes (FLSs) stimulated by tumor necrosis factor α (TNF-α).

METHODS

The direct relationship between miR-130a-3p and circRNA circ_0130438 or KLF9 was predicted by bioinformatics analysis and examined by a dual-luciferase reporter or RNA immunoprecipitation (RIP) assay. CircRNA circ_0130438, miR-130a-3p and KLF9 factor expression levels were gauged by a quantitative real-time PCR (qRT-PCR) or a western blot method. Cell proliferation ability was analyzed by a 5-Ethynyl-2'-Deoxyuridine (EdU) staining assay. The transwell assay was used to evaluate cell migration and invasion capacities. The production levels of interleukin-1β (IL)-1β, IL-6 and IL-8 were assessed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The level of circRNA circ_0130438 was reduced in RA tissues (P = 0.0001) and FLSs isolated from RA tissues (P = 0.0001) compared with corresponding normal controls. Exposure of human fibroblast-like MH7A synoviocytes to TNF-α suppressed circRNA circ_0130438 expression (P < 0.0001). In contrast, the elevated expression of circRNA circ_0130438 suppressed the TNF-α-induced proliferation (P = 0.0047) and migration (P = 0.0023) of MH7A cells, as well as their pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) production (P < 0.0001, P < 0.0001 and P < 0.0001). The circRNA circ_0130438 contained a miR-130a-3p binding site. Furthermore, the increase of miR-130-3p in TNF-α-stimulated MH7A cells reversed the effects of circRNA circ_0130438 elevation on cell proliferation (P = 0.0006), migration (P = 0.0406) and pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) production (P = 0.0036, P < 0.0001 and P = 0.0004), indicating that miR-130a-3p was a functional mediator of circRNA circ_0130438 regulation. We also documented that KLF9 was a direct target and downstream effector of miR-130a-3p. Importantly, circRNA circ_0130438 enhanced KLF9 expression (P < 0.0001) in TNF-α-stimulated MH7A cells by functioning as a competing endogenous RNA (ceRNA) for miR-130a-3p (P = 0.0004).

CONCLUSION

Our findings demonstrate that the elevated expression of circRNA circ_0130438 suppresses TNF-α-induced migration, proliferation and pro-inflammatory cytokines (IL-1β, IL-6 and IL-8) production of human MH7A cells by enhancing KLF9 expression by operating as a ceRNA for miR-130a-3p.

The Expression Level of FOXO3a in Patients With Autoimmune Diseases: A Meta-analysis

METHODS

PubMed, Web of Science, and China National Knowledge Infrastructure were used to retrieve relevant articles. The pooled standard mean difference with 95% confidence interval was calculated.

RESULTS

Totally, 10 studies from 7 publications were included. The levels of FOXO3a were significantly decreased in patients with autoimmune diseases compared with healthy controls (standard mean difference, -1.045; 95% confidence interval, -1.892 to -0.197). When stratified by disease, FOXO3a levels were significantly decreased in rheumatoid arthritis (RA) and inflammatory bowel disease (IBD), but were significantly increased in systemic lupus erythematosus. FOXO3a levels of specific tissues or cells in patients with autoimmune diseases were significantly decreased, but no significant difference was observed in the subgroup of peripheral blood mononuclear cells. In the subgroup analysis combining disease and sample, significant differences of FOXO3a were observed in non-PMBCs of RA and IBD patients.

CONCLUSIONS

Our study indicated that FOXO3a were significantly decreased in patients with autoimmune diseases. FOXO3a levels was a potential therapeutic target of autoimmune diseases.

14-3-3η Promotes Invadosome Formation via the FOXO3-Snail Axis in Rheumatoid Arthritis Fibroblast-like Synoviocytes

Erosive destruction of joint structures is a critical event in the progression of rheumatoid arthritis (RA), in which fibroblast-like synoviocytes (FLS) are the primary effectors. We previously reported that the ability of RA FLS to degrade extracellular matrix (ECM) components depends on the formation of actin-rich membrane protrusions, called invadosomes, through processes that remain elusive. 14-3-3η belongs to a family of scaffolding proteins involved in a wide range of cellular functions, and its expression is closely related to joint damage and disease activity in RA patients. In this study, we sought to assess the role of 14-3-3η in joint damage by examining its contribution to the invadosome formation phenotype of FLS. Using human primary FLS, we show that 14-3-3η expression is closely associated with their ability to form invadosomes. Furthermore, knockdown of 14-3-3η using shRNAs decreases the level of invadosome formation in RA FLS, whereas addition of the recombinant protein to FLS from healthy individuals promotes their formation. Mechanistic studies suggest that 14-3-3η regulates invadosome formation by increasing Snail expression, a mechanism that involves nuclear exclusion of the transcription repressor FOXO3. Our results implicate the 14-3-3η–FOXO3–Snail axis in promoting the aggressive ECM-degrading phenotype of RA FLS, and suggest a role for this scaffolding protein in cartilage degradation.

Epigenetic drug development for autoimmune and inflammatory diseases

ES-62 is the major secreted protein of the parasitic filarial nematode, Acanthocheilonema viteae. The molecule exists as a large tetramer (MW, ~240kD), which possesses immunomodulatory properties by virtue of multiple phosphorylcholine (PC) moieties attached to N-type glycans. By suppressing inflammatory immune responses, ES-62 can prevent disease development in certain mouse models of allergic and autoimmune conditions, including joint pathology in collagen-induced arthritis (CIA), a model of rheumatoid arthritis (RA). Such protection is associated with functional suppression of "pathogenic" hyper-responsive synovial fibroblasts (SFs), which exhibit an aggressive inflammatory and bone-damaging phenotype induced by their epigenetic rewiring in response to the inflammatory microenvironment of the arthritic joint. Critically, exposure to ES-62 in vivo induces a stably-imprinted CIA-SF phenotype that exhibits functional responses more typical of healthy, Naïve-SFs. Consistent with this, ES-62 "rewiring" of SFs away from the hyper-responsive phenotype is associated with suppression of ERK activation, STAT3 activation and miR-155 upregulation, signals widely associated with SF pathogenesis. Surprisingly however, DNA methylome analysis of Naïve-, CIA- and ES-62-CIA-SF cohorts reveals that rather than simply preventing pathogenic rewiring of SFs, ES-62 induces further changes in DNA methylation under the inflammatory conditions pertaining in the inflamed joint, including targeting genes associated with ciliogenesis, to programme a novel "resolving" CIA-SF phenotype. In addition to introducing a previously unsuspected aspect of ES-62's mechanism of action, such unique behaviour signposts the potential for developing DNA methylation signatures predictive of pathogenesis and its resolution and hence, candidate mechanisms by which novel therapeutic interventions could prevent SFs from perpetuating joint inflammation and destruction in RA. Pertinent to these translational aspects of ES-62-behavior, small molecule analogues (SMAs) based on ES-62's active PC-moieties mimic the rewiring of SFs as well as the protection against joint disease in CIA afforded by the parasitic worm product.

Punicalin alleviates TNF-α- and IL-1β-induced chondrocyte dysfunction and cartilage metabolism via mediating FOXO3 signaling axis

Forkhead box O3 (FOXO3) transcription factor is involved in chondral homeostasis of normal, aging and osteoarthritis (OA) cartilage. At present, we aimed to investigate whether FOXO3 is a target of punicalin to prevent IL-1β- and TNF-α-induced chondrocyte dysfunction in vitro and in vivo models. Cell and mouse models of chondrocyte dysfunction were established to determine the pharmacological value of hydrolyzable tannin, punicalin, which was extracted from the pomegranate. FOXO3 protein levels in the nucleus and cytoplasm were analysed using western blot. Safranine O staining was performed to evaluate the expansion of growth plate and chondrocyte differentiation in IL-1β- and TNF-α-treated mice. In IL-1β- and TNF-α-treated chondrocytes and mice, IL-1β and TNF-α evoked phosphorylation and nucleocytoplasmic shuttling of FOXO3, as well as reduced FOXO3 expression levels in the nucleus. However, punicalin treatment repressed FOXO3 phosphorylation and cytoplasmic transfer. Punicalin treatment improved IL-1β and TNF-α-induced growth inhibition and apoptosis of chondrocyte and the abnormal expansion of growth plate and hypertrophic zone. Moreover, punicalin could maintain the normal phenotype of chondrocyte via mediating multiple gene expression. Punicalin showed a beneficial effect on IL-1β- and TNF-α-stimulated chondrocytes and cartilaginous metabolic disorders via preserving the transcriptional activity of FOXO3. PRACTICAL APPLICATIONS: Our study presents a prospective adjuvant therapeutic drug, punicalin, to prevent inflammation-related cartilage injury and chondrocyte dysfunction.

Metformin Attenuates ROS via FOXO3 Activation in Immune Cells

Forkhead box O 3 (FOXO3) is a transcription factor involved in cell metabolism, inflammation and longevity. Here, we investigated if metformin can activate FOXO3 in human immune cells and affects the subsequent level of reactive oxygen/nitrogen species (ROS/RNS) in immune cells. AMP-activated protein kinase (AMPK) and FOXO3 activation were investigated by immunoblot or flow cytometry (FC) analysis, respectively. FOXO3 target gene expression was quantified by real-time PCR. ROS/RNS measurement using dichlorodihydrofluorescein diacetate (DCFH-DA) dye was investigated by FC. The role of the FOXO3 single nucleotide polymorphisms (SNPs) rs12212067, rs2802292 and rs12206094 on ROS/RNS production was studied using allelic discrimination PCR. Metformin induced activation of AMPK (pT172) and FOXO3 (pS413). ROS/RNS level was reduced in immune cells after metformin stimulation accompanied by induction of the FOXO3 targets mitochondrial superoxide dismutase and cytochrome c. Studies in Foxo3 deficient (Foxo3-/- ) mouse splenocytes confirmed that metformin mediates its effects via Foxo3 as it attenuates ROS/RNS in myeloid cells of wildtype (WT) but not of Foxo3-/- mice. Our results suggest that FOXO3 can be activated by metformin leading to reduced ROS/RNS level in immune cells. This may add to the beneficial clinical effects of metformin observed in large cohort studies on longevity, cardiovascular and cancer risk.

Down-Regulation of microRNA-30d Alleviates Intervertebral Disc Degeneration Through the Promotion of FOXO3 and Suppression of CXCL10

MicroRNAs (miRNAs/miRs) are important biomarkers for the progression of intervertebral disc degeneration (IDD). We investigated the role of miR-30d in IDD progression through its interactions with forkhead box O3 (FOXO3) and C-X-C motif ligand 10 (CXCL10). We first measured the expression of miR-30d, FOXO3, and CXCL10 in NP cells cultured from IDD patients. RNA-immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were then employed to test the relationship among miR-30d, FOXO3, and CXCL10. Besides, gain- and loss-of function approaches were performed to assess the functional roles of miR-30d and FOXO3 in IDD in vitro and in vivo. We found high expression of miR-30d and CXCL10 and low expression of FOXO3 in IDD. We showed that miR-30d specifically targeted FOXO3, and that down-regulation of miR-30d promoted proliferation and inhibited apoptosis of NP cells in IDD by increasing the expression of FOXO3. Besides, FOXO3 inhibited apoptosis of NP cells by downregulation of CXCL10 expression. Moreover, inhibition of miR-30d promoted proliferation and inhibited apoptosis of NP cells in IDD by decreasing CXCL10. Furthermore, findings in the mouse IDD model confirmed the inhibitory role of decreased miR-30d in IDD progression. Thus, we show that downregulation of miR-30d could promote the proliferation of NP cells by increasing FOXO3 and decreasing CXCL10 expression, which may provide a novel therapeutic target for IDD.

Role of Forkhead box O3a transcription factor in autoimmune diseases

Forkhead box O3a (FOXO3a) transcription factor, the most important member of Forkhead box O family, is closely related to cell proliferation, apoptosis, autophagy, oxidative stress and aging. The downregulation of FOXO3a has been verified to be associated with the poor prognosis, severer malignancy and chemoresistance in several human cancers. The activity of FOXO3a mainly regulated by phosphorylation of protein kinase B. FOXO3a plays a vital role in promoting the apoptosis of immune cells. FOXO3a could also modulate the activation, differentiation and function of T cells, regulate the proliferation and function of B cells, and mediate dendritic cells tolerance and immunity. FOXO3a accommodates the immune response through targeting nuclear factor kappa-B and FOXP3, as well as regulating the expression of cytokines. Besides, FOXO3a participates in intercellular interactions. FOXO3a inhibits dendritic cells from producing interleukin-6, which inhibits B-cell lymphoma-2 (BCL-2) and BCL-XL expression, thereby sparing resting T cells from apoptosis and increasing the survival of antigen-stimulated T cells. Recently, plentiful evidences further illustrated the significance of FOXO3a in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, ankylosing spondylitis, myositis, multiple sclerosis, and systemic sclerosis. In this review, we focused on the biological function of FOXO3a and related signaling pathways regarding immune system, and summarized the potential role of FOXO3a in the pathogenesis, progress and therapeutic potential of autoimmune diseases.

Rapid remission of refractory synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome in response to the Janus kinase inhibitor tofacitinib: A case report

BACKGROUND

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare autoinflammatory disease for which clinical treatment has not been standardized. Janus kinase (JAK) inhibitors represent a novel therapeutic option for rheumatoid arthritis, psoriatic arthritis, and some other autoinflammatory diseases. However, the clinical utility of JAK inhibitors in treating SAPHO syndrome has not been thoroughly investigated. In this study, we describe a patient with SAPHO syndrome who failed to respond to conventional treatment but demonstrated a remarkable and rapid response to the JAK inhibitor tofacitinib.

CASE SUMMARY

A 62-year-old female patient presented with swelling and pain at the sternoclavicular joints, back pain that limited her activities, arthralgia in the right knee, and cutaneous lesions. Her symptoms were unresponsive to nonsteroidal anti-inflammatory drugs, disease-modifying antirheumatic drugs, Tripterygium wilfordii hook f, and bisphosphonates. SAPHO syndrome was diagnosed in accordance with dermatological and osteoarticular manifestations and abnormal inflammatory factors. Multiple image studies have illustrated bone lesions and pathological fractures of vertebral bodies. Oral treatment with tofacitinib at 5 mg twice daily with methotrexate and bisphosphonates was initiated. The patient reported that her pain symptoms were relieved after 3 d and her cutaneous lesions were reduced after 4 wk of treatment. Vertebral lesions were improved after 6 mo on tofacitinib. No serious adverse effects were noted.

CONCLUSION

JAK inhibitor therapy may be a promising strategy to treat SAPHO syndrome.

The immunobiology of mTOR in autoimmunity

The mechanistic target of rapamycin (mTOR) is a master regulator of the inflammatory response in immune and non-immune cells. In immune cells mTOR regulates metabolism to fuel cell fate decision, proliferation and effector functions. In non-immune cells, such as fibroblast, it controls inflammation-associated proliferation and migration/invasion, shapes the expression of cytokines and chemokines and promotes extracellular matrix remodeling and fibrosis. Hence, mTOR plays a critical role in chronic inflammation, where a continuous feedback between stromal cells and infiltrating immune cells result in tissue remodeling and organ damage. Activation of mTOR has been implicated in a number of chronic inflammatory diseases, especially rheumatic diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), sjögren syndrome (SS) and seronegative spondyloarthropathy (SpA). Here we review recent advances in our understanding of the mechanism of mTOR activation in inflammation, especially in rheumatic diseases. We further discuss recent findings regarding the beneficial and side effects of mTOR inhibition in rheumatic conditions.