Inhibition Effects and Mechanisms of Marine Compound Mycophenolic Acid Methyl Ester against Influenza A Virus.

Influenza A virus (IAV) can cause infection and illness in a wide range of animals, including humans, poultry, and swine, and cause annual epidemics, resulting in thousands of deaths and millions of hospitalizations all over the world. Thus, there is an urgent need to develop novel anti-IAV drugs with high efficiency and low toxicity. In this study, the anti-IAV activity of a marine-derived compound mycophenolic acid methyl ester (MAE) was intensively investigated both in vitro and in vivo. The results showed that MAE inhibited the replication of different influenza A virus strains in vitro with low cytotoxicity. MAE can mainly block some steps of IAV infection post adsorption. MAE may also inhibit viral replication through activating the cellular Akt-mTOR-S6K pathway. Importantly, oral treatment of MAE can significantly ameliorate pneumonia symptoms and reduce pulmonary viral titers, as well as improving the survival rate of mice, and this was superior to the effect of oseltamivir. In summary, the marine compound MAE possesses anti-IAV effects both in vitro and in vivo, which merits further studies for its development into a novel anti-IAV drug in the future.

Preliminary Study: 3D Nailing for Intertrochanteric Femur Fractures.

Objective: This study introduced the structural features of the Three-Dimensional Proximal Femoral Nail (3DPFN), a patented invention, and highlights its advantages in treating intertrochanteric fractures of the femur. Furthermore, biomechanical comparative experiments validated the biomechanical performance of 3DPFN in treating Evans-Jensen type IV intertrochanteric fractures. Methods: Evans-Jensen type IV intertrochanteric fracture models were created using artificial femurs produced by the American company Sawbone. From January to April 2022, the experimental group was fixed with 3DPFN, while the control group was fixed with the Proximal Femoral Nail Antirotation (PFNA), simulating the loading conditions in the human body. Axial static ultimate pressure tests and dynamic fatigue tests were conducted. The recorded parameters included the maximum load-bearing capacity under axial load, the maximum number of cycles, and the maximum load before failure. Results: Static ultimate pressure tests showed that the static ultimate load in the 3DPFN group was 2532.67±49.20N, whereas in the PFNA group, it was 2240.00±84.35N, with a significant difference between the two groups (P < .05). Dynamic fatigue tests revealed that the maximum number of cycles in the 3DPFN group was 86372.67±4762.59 cycles, while in the PFNA group, it was 8606.67±606.05 cycles, also showing a significant difference (P < .05). Dynamic fatigue tests further indicated that the fatigue limit load before failure in the 3DPFN group was 1664.00±78.27N, whereas in the PFNA group, it was 799.33±63.52N. Again, there was a significant difference between the two groups (P < .05). Conclusion: In both static compression and fatigue tests, 3DPFN exhibits significant biomechanical advantages over PFNA. This suggests that 3DPFN may be an excellent choice for the treatment of intertrochanteric fractures of the femur and holds further research value for development. Future studies may involve clinical trials to validate and refine the 3DPFN design based on the observed results and promote the advancement of orthopedic implant technology.

Light-Regulated Nucleation for Growing Highly Uniform Single-Crystalline Microrods.

We report a light-irradiation method to control the synchronous nucleation of a donor-acceptor (D-A) fluorophore for growing highly uniform single-crystalline microrods, which is in sharp contrast to the prevailing methods of restricting spontaneous nucleation and additionally adding seeds. The D-A fluorophore was observed to undergo photoinduced electron transfer to CrCl3, leading to the generation of HCl and the subsequent protonation of the D-A fluorophore. By intensifying photoirradiation or prolonging its duration, the concentration of protonated D-A fluorophores can be rapidly increased to a high supersaturation level. This results in the formation of a controlled number of nuclei in a synchronous manner, which in turn kickstart the epitaxial growth of protonated D-A fluorophores towards uniform single-crystalline microrods of controlled sizes. The light-regulated synchronous nucleation and uniform growth of microrods are a unique phenomenon that can only be achieved by specific Lewis acids, making it a novel probing method for sensitively detecting strong Lewis acids such as chromium chloride.

Nickel Glyoximate Based Metal-Covalent Organic Frameworks for Efficient Photocatalytic Hydrogen Evolution.

Metal-covalent organic frameworks (MCOFs) have been recently received wide attention owing to the homogeneous distribution of active metal centers that are beneficial for enhancing the application potentials. However, metal complex based functional building blocks for MCOFs synthesis are limited. Herein, two new MCOFs (Ni-Py-COF and Ni-Bn-COF) were constructed via a novel nickel glyoximate based building block. Splendid photocatalytic activity on hydrogen evolution from water and great long-term recyclability were achieved using these nickel glyoximate based MCOFs as photocatalysts. Excitingly, even without the addition of Pt co-catalyst, the hydrogen evolution rates (HER) of Ni-Py-COF reached up to 626 µmol g-1 h-1 , which is better than many porous organic polymers. This work not only expands the type of building units for MCOFs, but also provides meaningful insights for developing stable, efficient and earth-abundant photocatalysts toward H2 generation.

Study on strategies for alighting and boarding in subway stations.

With its high infection rate, COVID-19 has swept the globe and brought great challenges to social life and economies. As an essential form of public transportation, the Beijing subway plays an important role in transportation systems. In traditional subway organizations, all one-sided doors of a train carriage are employed for passengers' alighting and boarding. A higher risk of COVID-19 infections may be attributed to inevitable bidirectional conflicts at doors with higher passenger volumes. Moreover, quantitative analyses for this problem and corresponding solutions are, limited in recent studies. In this research, conflicts at carriage doors are analyzed using a cellular automaton (CA) based model. Four schemes to separate alighting and passenger boarding into separate doors are investigated. The performances of different schemes with various alighting and boarding passenger ratios are simulated with the software package Legion Studio. Both macroscopic and microscopic parameters to characterize passenger conflicts are obtained for analysis. The separation of alighting and boarding passenger flows yields the desired reduction in bidirectional conflicts, which further limits the probability of infectious disease exposure. This is an important reference to improve current practices and provide specific measurements of passenger organization under abnormal situations.

Low LPA gene kringle IV-2 repeat copy number association with elevated lipoprotein (a) concentration as an independent risk factor of coronary atherosclerotic heart disease in the Chinese Han population.

BACKGROUND: Lipoprotein (a) [Lp(a)], which is genetically determined by the LPA gene kringle IV type 2 (KIV-2) repeat copy number, has previously been reported in different populations. However, it is uncertain if the same occurs in the Chinese Han population. This study explored the correlation of Lp(a) mass or particle concentration with KIV-2 repeat copy number and application for coronary atherosclerotic heart disease (CAHD) risk assessment. METHODS: A cross-sectional study including 884 subjects was conducted. The Lp(a) level and routine risk factors of CAHD were compared. The KIV-2 copy number distribution, relationship with Lp(a), and assessment for CAHD risk were explored. RESULTS: The mean of Lp(a) mass or particle concentration in the CAHD group was higher than that in the non-CAHD group, while the KIV-2 copy number in the CAHD group was lower. Lp(a) had auxiliary values in gauging the type of plaque and was significantly higher in the soft-plaque group than that in the other two groups (200 mg/L [21.5 nmol/L], 166 mg/L [18.6 nmol/L], 149 mg/L [17.1 nmol/L], respectively, P < 0.05). Kappa test indicated divergence for the same individual using two Lp(a) concentrations (kappa value was 0.536 [< 0.75]). Elevated Lp(a) was an independent CAHD risk factor, whatever mass or particle concentration, and large KIV-2 copy number was a protective factor. CONCLUSION: Lp(a) level and small KIV-2 copy number are risk factors for CAHD in the Chinese Han population; furthermore, elevated Lp(a) may gauge the type of coronary plaque.

Preparation and characterization of kelp polysaccharide and its research on anti-influenza a virus activity.

The beneficial effects of kelp polysaccharide (KPS) have recently attracted attention. In this study, KPS was extracted from kelp using the enzyme hydrolysis combined with freeze-drying, namely, KPS-EF. The structural characterization showed that KPS-EF was a highly sulfated macromolecule with the Mw of 764.2 kDa and the sulfate content of 23.49 %. The antiviral activity of KPS-EF in vitro was verified, and the IC50 value of KPS against the PR8 virus was 0.58 mg/mL. Intranasal administration of KPS-EF significantly inhibited death and weight loss in IAV-infected mice and alleviated virus-induced pneumonia symptoms, meanwhile, KPS-EF (10 mg/kg/day) significantly decreased the production levels of chemokines (CXCL1, RANTES) and inflammatory cytokines (IL-6, TNF-α) in lungs (p < 0.05). KPS-EF could downregulate the activity of viral neuraminidase (NA) primarily in the late stage of viral adsorption with an IC50 value of 0.29 mg/mL. This study provides a theoretical basis for the using KPS as a supplement to NA inhibitors or anti-influenza drugs.

Screening and optimization of shark nanobodies against SARS-CoV-2 spike RBD.

SARS-CoV-2 continues to threaten human health, antibody therapy is one way to control the infection. Because new SARS-CoV-2 mutations are constantly emerging, there is an urgent need to develop broadly neutralizing antibodies to block the viral entry into host cells. VNAR from sharks is the smallest natural antigen binding domain, with the advantages of small size, flexible paratopes, good stability, and low manufacturing cost. Here, we used recombinant SARS-CoV-2 Spike-RBD to immunize sharks and constructed a VNAR phage display library. VNAR R1C2, selected from the library, efficiently binds to the RBD domain and blocks the infection of ACE2-positive cells by pseudovirus. Next, homologous bivalent VNARs were constructed through the tandem fusion of two R1C2 units, which enhanced both the affinity and neutralizing activity of R1C2. R1C2 was predicted to bind to a relatively conserved region within the RBD. By introducing mutations at four key binding sites within the CDR3 and HV2 regions of R1C2, the affinity and neutralizing activity of R1C2 were significantly improved. Furthermore, R1C2 also exhibits an effective capacity of binding to the Omicron variants (BA.2 and XBB.1). Together, these results suggest that R1C2 could serve as a valuable candidate for preventing and treating SARS-CoV-2 infections.

Immune-enhancing activity of compound polysaccharide on the inactivated influenza vaccine.

Traditional Chinese medicine polysaccharides have numerous biological activities with broad applications in the biomedical industries. However, a clear understanding of the pharmacological activities of compound polysaccharides with multi-component structures remain challenging. This study aimed to investigate the immune boosting effect of compound polysaccharides on the influenza vaccine and assess the preliminary structure-activity relationship. The compound polysaccharide (CP) was isolated from the combined Chinese herbs lentinan, pachymaran and tremellan, and purified by gradient ethanol precipitation to obtain its subcomponents of CP-20, CP-40, CP-60, and CP-80 with decreasing molecular weights. These polysaccharides were mainly composed of glucans with different linkage patterns, including α-(1 â†’ 3)-glucan, α-(1 â†’ 4)-glucan and ß-(1 â†’ 6)-glucan. A significant improvement was observed in the survival of mice vaccinated with inactivated (IAV) vaccine and the isolated polysaccharides as adjuvants. A reduction in the pulmonary virus titer and weight loss were also observed. Moreover, CP-40 and CP-60, as well as the original CP, significantly enhanced the serum anti-IAV antibody titers and interleukin IL-2, IL-5, and IL-6 concentrations. These preliminary results indicate the immune boosting effect of the compound polysaccharides is highly relevant to the specific structural properties of the subcomponent, and CP-40 is worthy of further exploration as a glycan adjuvant for the IAV vaccine.

Inhibition of influenza a virus infection by natural stilbene piceatannol targeting virus hemagglutinin.

BACKGROUND: Given the magnitude of influenza pandemics as a threat to the global population, it is crucial to have as many prevention and treatment options as possible. Piceatannol (PIC) is a tetrahydroxylated stilbenoid (trans-3,4,3',5'-tetrahydroxystilbene), also known as 3'- hydroxy resveratrol, which has demonstrated many different biological activities such as anti-inflammatory and antiviral activities. PURPOSE: In this study, the anti-influenza A virus (IAV) activities and mechanisms of PIC in vitro and in vivo were investigated in order to provide reference for the development of novel plant-derived anti-IAV drugs. METHODS: The viral plaque assay, RT-PCR and western blot assay were used to evaluate the anti-IAV effects of PIC in vitro. The anti-IAV mechanism of PIC was determined by HA syncytium assay, DARTS assay and Surface Plasmon Resonance assay. The mouse pneumonia model combined with HE staining were used to study the anti-IAV effects of PIC in vivo. RESULTS: PIC shows inhibition on the multiplication of both H1N1 and H3N2 viruses, and blocks the infection of H5N1 pseudovirus with low toxicity. PIC may directly act on the envelope of IAV to induce the rupture and inactivation of IAV particles. PIC can also block membrane fusion via binding to HA2 rather than HA1 and cleavage site of HA0. PIC may interact with the two residues (HA2-T68 and HA2-I75) of HA2 to block the conformational change of HA so as to inhibit membrane fusion. Importantly, oral therapy of PIC also markedly improved survival and reduced viral titers in IAV-infected mice. CONCLUSION: PIC possesses significant anti-IAV effects both in vitro and in vivo and may block IAV infection mainly through interaction with HA to block membrane fusion. Thus, PIC has the potential to be developed into a new broad-spectrum anti-influenza drug for the prevention and treatment of influenza.

Inhibitory effects and mechanisms of proanthocyanidins against enterovirus 71 infection.

Proanthocyanidins (PC), a natural flavonoid compound, was reported to possess a variety of pharmacological activities such as anti-tumor and anti-viral effects. In this study, the anti-Enterovirus 71 (EV71) activities and mechanisms of PC were investigated both in vitro and in vivo. The results showed that PC possessed anti-EV71 activities in different cell lines with low toxicity. PC can block both the adsorption and entry processes of EV71 via directly binding to virus VP1 protein. PC may competitively interfere with the binding of VP1 to its receptor SCARB2. PC can also regulate three different MAPK signaling pathways to reduce EV71 infection and attenuate virus induced inflammatory responses. Importantly, intramuscular therapy of EV71-infected mice with PC markedly improved their survival and attenuated the severe clinical symptoms. Therefore, the natural compound PC has potential to be developed into a novel anti-EV71 agent targeting viral VP1 protein and MAPK pathways.

Inhibition of herpes simplex virus by wedelolactone via targeting viral envelope and cellular TBK1/IRF3 and SOCS1/STAT3 pathways.

OBJECTIVES: Development of novel antiherpes simplex virus (HSV) agents with active mechanisms different from nucleoside analogues is of high importance. Herein, we investigated the anti-HSV activities and mechanisms of wedelolactone (WDL) both in vitro and in vivo. METHODS: Cytopathic effect (CPE) inhibition assay, plaque assay, and western blot assay were used to evaluate the anti-HSV effects of WDL in vitro. The immunofluorescence assay, RT-PCR assay, plaque reduction assay, sandwich ELISA assay, syncytium formation assay, tanscriptome analysis and western blot assay were used to explore the anti-HSV mechanisms of WDL. The murine encephalitis and vaginal models of HSV infection were performed to evaluate the anti-HSV effects of WDL in vivo. RESULTS: WDL possessed inhibitory effects against both HSV-1 and HSV-2 in different cells with low toxicity, superior to the effects of acyclovir. WDL can directly inactivate the HSV particle via destruction of viral envelope and block HSV replication process after virus adsorption, different from the mechanisms of acyclovir. WDL may influence the host genes and signaling pathways related to HSV infection and immune responses. WDL can mainly interfere with the TBK1/IRF3 and SOCS1/STAT3 pathways to reduce HSV infection and inflammatory responses. Importantly, WDL treatment markedly improved mice survival, attenuated inflammatory symptoms, and reduced the virus titres in both HSV-1 and HSV-2 infected mice. CONCLUSIONS: Thus, the natural compound WDL has the potential to be developed into a novel anti-HSV agent targeting both viral envelope and cellular TBK1/IRF3 and SOCS1/STAT3 pathways.

Silencing of circCYP51A1 represses cell progression and glycolysis by regulating miR-490-3p/KLF12 axis in osteosarcoma under hypoxia.

Background: Hypoxia is a key characteristic of osteosarcoma (OS). Increasing data suggested that circular RNA (circRNAs) were involve in the progression of cancers and the regulation of hypoxia, including OS. This study aims to examine the biological mechanism of circRNA cytochrome P450 family 51 subfamily A member 1 (circCYP51A1) in OS under hypoxia. Methods: The expression levels of circCYP51A1, microRNA-490-3p (miR-490-3p) and kruppel-like factor 12 (KLF12) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in OS tissues and cells. Cell proliferation, migration and invasion were determined by colony formation assay and transwell assay. Lactate production and glucose consumption in OS cells were measured by using lactate assay kit and glucose assay kit, respectively. Western blot assay and immunohistochemistry assay were used to test protein levels. The associated relationship between miR-490-3p and circCYP51A1 or KLF12 was predicted using Starbase or DIANA online database and verified by dual-luciferase reporter assay. The xenograft model was used to explore the role of circCYP51A1 in vivo. Results: CircCYP51A1 and KLF12 expression were dramatically increased, whereas miR-490-3p was decreased in OS cells under hypoxia condition. Deficiency of circCYP51A1 hindered hypoxia-induced cell proliferation, migration, invasion and glycolysis in OS cells. CircCYP51A1 enhanced KLF12 expression by sponging miR-490-3p. MiR-490-3p inhibitor weakened the inhibition effect of circCYP51A1 knockdown on the progression of OS under hypoxia. Besides, overexpression of miR-490-3p inhibited cell progression of OS under hypoxia condition, while the effects were attenuated by KLF12 overexpression. Importantly, knockdown of circCYP51A1 inhibited tumor growth in vivo. Conclusion: CircCYP51A1 mediated cell proliferation, migration, invasion and glycolysis by regulating miR-490-3p/KLF12 axis in OS cells under hypoxia condition.

The inhibition effects and mechanisms of sulfated chitooligosaccharides on influenza A virus in vitro and in vivo.

Sulfated chitooligosaccharide was reported to possess inhibition effect on human immunodeficiency virus (HIV) entry into host cells. Herein, we prepared chitooligosaccharide COS and its sulfate derivative SCOS and explored whether the sulfation modification can enhance the anti-influenza A virus (IAV) activity of COS. Interestingly, we discovered that SCOS possessed broad-spectrum anti-IAV effects with low toxicity, while the non-sulfated chitooligosaccharide COS had very low inhibition on IAV, verifying that the sulfation modification is essential for the anti-IAV actions of chitooligosaccharide. SCOS may target virus hemagglutinin (HA) protein to block both virus adsorption and membrane fusion processes. Oral administration of SCOS significantly decreased pulmonary viral titers and improved survival rate in IAV infected mice, comparable to the effects of Oseltamivir. Therefore, our findings support further studies on the use of SCOS as a novel entry inhibitor for IAV and as a supplement to current therapeutics for influenza.

Reducing the impact of speed dispersion on subway corridor flow.

The rapid increase in the volume of subway passengers in Beijing has necessitated higher requirements for the safety and efficiency of subway corridors. Speed dispersion is an important factor that affects safety and efficiency. This paper aims to analyze the management control methods for reducing pedestrian speed dispersion in subways. The characteristics of the speed dispersion of pedestrian flow were analyzed according to field videos. The control measurements which were conducted by placing traffic signs, yellow marking, and guardrail were proposed to alleviate speed dispersion. The results showed that the methods of placing traffic signs, yellow marking, and a guardrail improved safety and efficiency for all four volumes of pedestrian traffic flow, and the best-performing control measurement was guardrails. Furthermore, guardrails' optimal position and design measurements were explored. The research findings provide a rationale for subway managers in optimizing pedestrian traffic flow in subway corridors.

Long noncoding RNA LeXis promotes osteosarcoma growth through upregulation of CTNNB1 expression.

Osteosarcoma (OS) is the most common primary bone cancer in adolescents and children. Long noncoding RNAs (lncRNAs) contain > 200 nucleotides and do not have protein-coding ability. Liver-expressed LXR-induced sequence (LeXis) is a newly identified functional lncRNA. However, its expression pattern, biological function, and molecular mechanism in OS progression are unclear. The present study is the first to show that LeXis expression was upregulated in OS tissues. Increased LeXis expression was significantly correlated with high tumor stage, large tumor size, and poor prognosis. Our findings highlight the oncogenic activity of lncRNA LeXis in OS growth. Results of functional assays showed that LeXis promoted OS growth both in vitro and in vivo. Mechanistic investigation showed that LeXis directly interacted with miR-199a and suppressed its expression. Moreover, LeXis increased CTNNB1 expression by functioning as a ceRNA of CTNNB1 against miR-199a. These findings may have important implications for developing novel therapeutic strategies for OS.

Lnc­IL7R promotes the growth of fibroblast­like synoviocytes through interaction with enhancer of zeste homolog 2 in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an inflammatory and autoimmune disease that affects ~1% of the world's population. Although the precise mechanism of RA has yet to be elucidated, accumulating evidence suggests that fibroblast­like synoviocytes (FLSs) serve critical roles in the initiation and progression of RA. However, the underlying molecular mechanisms of FLS proliferation have yet to be elucidated. Long noncoding­interleukin­7 receptor (lnc­IL7R) has been recently identified, which is activated by lipopolysaccharide (LPS) stimulation and diminishes the LPS­induced inflammatory response. In the present study, gain­ and loss­of­function assays were performed in order to investigate the role of lnc­IL7R in FLS. It is demonstrated, to the best of the authors' knowledge for the first time, that lnc­IL7R promotes cell proliferation, cell cycle progression and inhibits apoptosis in FLS. Further investigation identified that lnc­IL7 interacts with enhancer of zeste homolog 2 (EZH2) and is required for polycomb repressive complex 2 (PRC2)­mediated suppression, including cyclin­dependent kinase inhibitor 1A and cyclin­dependent kinase inhibitor 2A. Lnc­IL7R may be a promising therapeutic target for the treatment of RA.

Glucose-6-Phosphate Isomerase (G6PI) Mediates Hypoxia-Induced Angiogenesis in Rheumatoid Arthritis.

The higher level of Glucose-6-phosphate isomerase (G6PI) has been found in both synovial tissue and synovial fluid of rheumatoid arthritis (RA) patients, while the function of G6PI in RA remains unclear. Herein we found the enrichment of G6PI in microvascular endothelial cells of synovial tissue in RA patients, where a 3% O2 hypoxia environment has been identified. In order to determine the correlation between the high G6PI level and the low oxygen concentration in RA, a hypoxia condition (~3% O2) in vitro was applied to mimic the RA environment in vivo. Hypoxia promoted cellular proliferation of rheumatoid arthritis synovial fibroblasts (RASFs), and induced cell migration and angiogenic tube formation of human dermal microvascular endothelial cells (HDMECs), which were accompanied with the increased expression of G6PI and HIF-1α. Through application of G6PI loss-of-function assays, we confirmed the requirement of G6PI expression for those hypoxia-induced phenotype in RA. In addition, we demonstrated for the first time that G6PI plays key roles in regulating VEGF secretion from RASFs to regulate the hypoxia-induced angiogenesis in RA. Taken together, we demonstrated a novel pathway regulating hypoxia-induced angiogenesis in RA mediated by G6PI.

Long Noncoding RNA EWSAT1 Promotes Osteosarcoma Cell Growth and Metastasis Through Suppression of MEG3 Expression.

Osteosarcoma (OS) is the most common primary bone tumor in children and adolescents. Long noncoding RNAs (lncRNAs) are a class of transcriptional products of the genome without protein-coding potential. Recently, lncRNA Ewing sarcoma-associated transcript 1 (EWSAT1) was functionally identified in Ewing sarcoma, a highly aggressive primary pediatric bone tumor. However, whether EWSAT1 plays a role in OS remains unclear. In the present study, gain- and loss-of-function assays demonstrated that EWSAT1 enhanced OS cell proliferation, migration, and invasion. Further mechanistic studies found that EWSAT1 positively regulated lncRNA MEG3 expression in the transcriptional level. Finally, we observed that EWSAT1 facilitates OS cell growth and metastasis through regulation of MEG3, suggesting that EWSAT1-MEG3 axis might be a promising target for OS treatment.

Glucose-6-phosphate isomerase promotes the proliferation and inhibits the apoptosis in fibroblast-like synoviocytes in rheumatoid arthritis.

INTRODUCTION: Fibroblast-like synoviocytes (FLS) play an important role in the pathogenesis of rheumatoid arthritis (RA). This study aimed to investigate the role of glucose 6-phosphate isomerase (GPI) in the proliferation of RA-FLS. METHODS: The distribution of GPI in synovial tissues from RA and osteoarthritis (OA) patients was examined by immunohistochemical analysis. FLS were isolated and cultured, cellular GPI level was detected by real-time polymerase chain reaction (PCR) and Western blot analysis, and secreted GPI was detected by Western blot and enzyme-linked immunosorbent assay (ELISA). Doxorubicin (Adriamycin, ADR) was used to induce apoptosis. Cell proliferation was determined by MTS assay. Flow cytometry was used to detect cell cycle and apoptosis. Secreted pro-inflammatory cytokines were measured by ELISA. RESULTS: GPI was abundant in RA-FLS and was an autocrine factor of FLS. The proliferation of both RA and OA FLS was increased after GPI overexpression, but was decreased after GPI knockdown. Meanwhile, exogenous GPI stimulated, while GPI antibody inhibited, FLS proliferation. GPI positively regulated its receptor glycoprotein 78 and promoted G1/S phase transition via extracellular regulated protein kinases activation and Cyclin D1 upregulation. GPI inhibited ADR-induced apoptosis accompanied by decreased Fas and increased Survivin in RA FLS. Furthermore, GPI increased the secretion of tumor necrosis factor-α and interleukin-1ß by FLS. CONCLUSIONS: GPI plays a pathophysiologic role in RA by stimulating the proliferation, inhibiting the apoptosis, and increasing pro-inflammatory cytokine secretion of FLS.