Ramulus Cinnamomi extract attenuates neuroinflammatory responses via downregulating TLR4/MyD88 signaling pathway in BV2 cells

Ramulus Cinnamomi （RC）, a traditional Chinese herb, has been used to attenuate inflammatory responses. The purpose of this study was to investigate the effect of RC extract on lipopolysaccharide （LPS）-induced neuroinflammation in BV2 microglial cells and the underlying mechanisms involved. BV2 cells were incubated with normal medium （control group）, LPS, LPS plus 30 pg/mL RC extract, or LPS plus 100 pg/mL RC extract. The BV2 cell morphology was observed under an optical microscope and cell viability was detected by MTT assay. Nitric oxide level in BV2 cells was detected using Griess regents, and the levels of interleukin-6, interleukin-1 β, and tumor necrosis factor u in BV2 cells were determined by ELISA. The expression levels of cyclooxygenase-2, Toll-like receptor 4 and myeloid differentiation factor 88 proteins were detected by western blot assay. Compared with the LPS group, both 30 and 100 μg/mL RC extract had no significant effect on the viability of BV2 cells. The levels of nitric oxide, interleukin-6, interleukin-1β and tumor necrosis factor ct in BV2 cells were all significantly increased after LPS induction, and the levels were significantly reversed after treatment with 30 and 100 μg/mL RC extract. Furthermore, RC extract significantly inhibited the protein expression levels of cyclooxygenase-2, Toll-like receptor 4 and myeloid differentiation factor 88 in LPS-induced BV2 cells. Our findings suggest that RC extract alleviates neuroinflammation by downregulating the TLR4/MyD88 signaling pathway.

Galectin-3 and IL-33/ST2 axis roles and interplay in dietinduced steatohepatitis

Immune reactivity and chronic low-grade inflammation(metaflammation) play an important role in the pathogenesis of obesity-associated metabolic disorders, including type 2 diabetes and nonalcoholic fatty liver disease(NAFLD), a spectrum of diseases that include liver steatosis, nonalcoholic steatohepatitis(NASH), fibrosis, and cirrhosis. Increased adiposity and insulin resistance contribute to the progression from hepatic steatosis to NASH and fibrosis through the development of proinflammatory and profibrotic processes in the liver, including increased hepatic infiltration of innate and adaptive immune cells, altered balance of cytokines and chemokines, increased reactive oxygen species generation and hepatocellular death. Experimental models of dietary-induced NAFLD/NASH in mice on different genetic backgrounds or knockout mice with different immune reactivity are used for elucidating the pathogenesis of NASH and liver fibrosis. Galectin-3(Gal-3), a unique chimera-type β-galactoside-binding protein of the galectin family has a regulatory role in immunometabolism and fibrogenesis. Mice deficient in Gal-3 develop pronounced adiposity, hyperglycemia and hepatic steatosis, as well as attenuated liver inflammation and fibrosis when fed an obesogenic high-fat diet. Interleukin(IL)-33, a member of the IL-1 cytokine family, mediates its effects through the ST receptor, which is present on immune and nonimmune cells and participates in immunometabolic and fibrotic disorders. Recent evidence, including our own data, suggests a protective role for the IL-33/IL-33R(ST2) signaling pathway in obesity, adipose tissue inflammation and atherosclerosis, but a profibrotic role in NASH development. The link between Gal-3 and soluble ST2 in myocardial fibrosis and heart failure progression has been demonstrated and we have recently shown that Gal-3 and the IL-33/ST2 pathway interact and both have a profibrotic role in diet-induced NASH. This review discusses the current evidence on the roles of Gal-3 and the IL-33/ST2 pathway and their interplay in obesity-associated hepatic inflammation and fibrogenesis that may be of interest in the development of therapeutic interventions to prevent and/or reverse obesity-associated hepatic inflammation and fibrosis.

Role of the IL-33-ST2 axis in sepsis

Sepsis remains a major clinical problem with high morbidity and mortality. As new inflammatory mediators are characterized, it is important to understand their roles in sepsis. Interleukin 33(IL-33) is a recently described member of the IL-1 family that is widely expressed in cells of barrier tissues. Upon tissue damage, IL-33 is released as an alarmin and activates various types of cells of both the innate and adaptive immune system through binding to the ST2/IL-1 receptor accessory protein complex. IL-33 has apparent pleiotropic functions in many disease models, with its actions strongly shaped by the local microenvironment. Recent studies have established a role for the IL-33-ST2 axis in the initiation and perpetuation of inflammation during endotoxemia, but its roles in sepsis appear to be organism and model dependent. In this review, we focus on the recent advances in understanding the role of the IL-33/ST2 axis in sepsis.

Serum soluble ST2 is a promising prognostic biomarker in HBV-related acute-on-chronic liver failure

BACKGROUND： The IL-33/ST2 axis is involved in the pathogenesis of many diseases such as autoimmune diseases, cancer,and heart failure. However, studies of the IL-33/ST2 pathway in HBV-related acute-on-chronic liver failure（HBV-ACLF） are lacking. The present study aimed to determine the prognostic role of serum IL-33/soluble ST2（s ST2） in HBV-ACLF.METHODS： Serum levels of IL-33 and sS T2 in healthy controls（HC, n=18）, chronic hepatitis B（CHB, n=27） and HBV-ACLF（n=51） patients at the 1st and 4th week after enrollment were detected using ELISA, and clinical data were collected. The follow-up of HBV-ACLF patients lasted for 6 months at least.RESULTS： There was no significant difference of serum IL-33 level among HC, CHB and HBV-ACLF patients at week 1.However, serum s ST2 level differed significantly among the three groups： highest in the HBV-ACLF group, moderate in the CHB group and lowest in the HC group. There was a reverse correlation between serum s ST2 level and the survival of HBV-ACLF patients. The level of serum s ST2 in HBV-ACLF survivors was significantly declined from week 1 to week 4 following the treatment, whereas that in HBV-ACLF nonsurvivors remained at a high level during the same period. Furthermore, serum sS T2 level was significantly correlated with laboratory parameters and the most updated prognostic scores（CLIF-C OF score, CLIF-C ACLF score and ACLF grades）. Thereceiver operating characteristics curves demonstrated that serum sS T2 level was a good diagnostic marker for predicting the 6-month mortality in HBV-ACLF patients, comparable to the most updated prognostic scores. Serum sS T2 cut-off points for predicting prognosis in HBV-ACLF patients were 76 ng/mL at week 1 or 53 ng/mL at week 4, respectively. HBV-ACLF patients with serum sS T2 level above the cut-off point often had a worse prognosis than those below the cut-off point.CONCLUSION： Serum s ST2 may act as a promising biomarker to assess severity and predict prognosis of patients with HBV-ACLF and help for the early identification and optimal treatment of HBV-ACLF patients at high risk of mortality.

Neuronal changes in the retinal ganglion cell layer following recombinant human interleukin-2 intravitreal injection in a rat model of chronically elevated intraocular pressure

Intraperitoneal injection of recombinant human interleukin-2（rhIL-2）inhibits neuronal apoptosis in the chronic ocular hypertension retinal ganglion cell layer.Intravitreous injection was performed on retinal ganglion cells in a Wistar rat model of chronically elevated intraocular pressure to observe the effects of LY294002 and AG490 on retinal ganglion cell survival,macrophage activation,and PI3K/Akt and JAK/STAT activation.The number of retinal ganglion cells in the rhIL-2 treatment group was much greater than in the normal control and phosphate-buffered saline groups.Western blot analysis revealed low Akt and STAT3 protein expression in the retina after 3-hour intravitreous injections of rhIL-2.However,protein expression was increased at 12 hours,but decreased again at 24 hours,with very low expression at 96 hours.LY294002 and AG490,which are inhibitors of the PI3K/Akt and JAK/STAT3 signal pathways,prevented upregulation of Akt and STAT3 protein expression in the retina,respectively.Intravitreous injection of rhIL-2 exhibited neuroprotective effects by decreasing retinal ganglion cell layer damage in a rat model of chronic glaucoma.These results suggest that intravitreal injection of rhIL-2 could induce the PI3K/Akt and JAK/STAT3 signaling pathways to protect retinal ganglion cells in chronically elevated intraocular pressure models.

Discovery of highly immunogenic spleen-resident FCGR3^(+)CD103^(+)cDC1s differentiated by IL-33-primed ST2^(+)basophils

Recombinant interleukin-33(IL-33)inhibits tumor growth,but the detailed immunological mechanism is still unknown.IL-33-mediated tumor suppression did not occur in Batf3^(−/−)mice,indicating that conventional type 1 dendritic cells(cDC1s)play a key role in IL-33-mediated antitumor immunity.A population of CD103^(+)cDC1s,which were barely detectable in the spleens of normal mice,increased significantly in the spleens of IL-33-treated mice.The newly emerged splenic CD103^(+)cDC1s were distinct from conventional splenic cDC1s based on their spleen residency,robust effector T-cell priming ability,and surface expression of FCGR3.DCs and DC precursors did not express Suppressor of Tumorigenicity 2(ST2).However,recombinant IL-33 induced spleen-resident FCGR3^(+)CD103^(+)cDC1s,which were found to be differentiated from DC precursors by bystander ST2+immune cells.Through immune cell fractionation and depletion assays,we found that IL-33-primed ST2^(+)basophils play a crucial role in the development of FCGR3^(+)CD103^(+)cDC1s by secreting IL-33-driven extrinsic factors.Recombinant GM-CSF also induced the population of CD103^(+)cDC1s,but the population neither expressed FCGR3 nor induced any discernable antitumor immunity.The population of FCGR3^(+)CD103^(+)cDC1s was also generated in vitro culture of Flt3L-mediated bone marrow-derived DCs(FL-BMDCs)when IL-33 was added in a pre-DC stage of culture.FL-BMDCs generated in the presence of IL-33(FL-33-DCs)offered more potent tumor immunotherapy than control Flt3L-BMDCs(FL-DCs).Human monocyte-derived DCs were also more immunogenic when exposed to IL-33-induced factors.Our findings suggest that recombinant IL-33 or an IL-33-mediated DC vaccine could be an attractive protocol for better tumor immunotherapy.

Calycosin-7-O-β-D-glucopyranoside stimulates osteoblast differentiation through regulating the BMP/WNT signaling pathways

The iso fl avone calycosin-7-O-β-D-glucopyranoside(CG) is a principal constituent of Astragalus membranaceus(AR) and has been reported to inhibit osteoclast development in vitro and bone loss in vivo. The aim of this study was to investigate the osteogenic effects of CG and its underlying mechanism in ST2 cells. The results show that exposure of cells to CG in osteogenic differentiation medium increases ALP activity, osteocalcin(Ocal) m RNA expression and the osteoblastic mineralization process. Mechanistically, CG treatment increased the expression of bone morphogenetic protein 2(BMP-2), p-Smad 1/5/8, β-catenin and Runx2, all of which are regulators of the BMP- or wingless-type MMTV integration site family(WNT)/β-catenin-signaling pathways. Moreover, the osteogenic effects of CG were inhibited by Noggin and DKK-1 which are classical inhibitors of the BMP and WNT/β-catenin-signaling pathways, respectively. Taken together, the results indicate that CG promotes the osteoblastic differentiation of ST2 cells through regulating the BMP/WNT signaling pathways. On this basis, CG may be a useful lead compound for improving the treatment of bone-decreasing diseases and enhancing bone regeneration.

Research progress on interleukin-33 and its roles in the central nervous system

Interleukin-33 （IL-33）, a newly recognized IL-1 family member, is expressed by various tissues and cells. Since it can combine with chromosomes, IL-33 is regarded as an intracellular transcription repressor. Upon proinflammatory stimulation, it is released as an extracellular cytokine to function as an alarmin to dangerous signals. The IL-33 receptor is a heterodimer complex composed of ST2 and the IL-1 receptor accessory protein, the latter being conserved in other IL-1 family members. The IL-33/ST2 signaling pathway plays critical roles in inflammatory and immune diseases, as well as in central nervous system （CNS） diseases. Recently, there has been an increasing focus on IL-33, particularly on its production and functions in the CNS. The present review mainly focuses on progress in research on IL-33, especially its roles in the CNS.

Effect of electroacupuncture on JAK2/STAT3 pathway in synovial tissues of rats with rheumatoid arthritis

Objective: To observe the effect of electroacupuncture (EA) on Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway in knee joint synovial tissues of rats with rheumatoid arthritis (RA) and to explore the action mechanism of EA on RA. Methods: Twelve of the 48 SPF male Sprague-Dawley (SD) rats were assigned to a normal group by the random number table method. The remaining 36 rats were subjected to RA model preparation by intradermal injection of the Freund's complete adjuvant into the right hind foot pad of each rat under sterile conditions. After the model was successfully prepared, rats were then divided into a model group, a drug group and an EA group according to a random number table method (n=12). Rats in the drug group were treated with 2 mL aqueous solution of tripterygium glycosides [8.1 mg/(kg?bw)];rats in the EA group were treated with EA at bilateral Yanglingquan (GB 34) and Zusanli (ST 36), for 30 min each time;rats in the normal group and the model group were placed in a special rat fixation tank for 30 min each time, and received the same dose of normal saline as those in the drug group. Rats in all groups received intervention once a day for 4 weeks. Diameter of rat ankle joint and rat arthritis index were measured before and after the intervention. At the end of the experiment, the expressions of phospho-JAK2 and phospho-STAT3 were determined by immunohistochemistry. Quantitative real-time polymerase chain reaction (RT-qPCR) was used to detect JAK2 and STAT3 mRNAs expressions. Results: After the model was produced, the arthritis index >2 was considered successful in model preparation. Compared with the model group, the ankle joint diameters and arthritis indexes of rats in the drug group and the EA group were significantly lower (all P<0.01);immunohistochemical staining cells with phospho-JAK2 and phospho-STAT3 were significantly decreased (all P<0.01);the expression levels of JAK2 and STAT3 mRNAs were decreased with statistical differences (all P<0.01). There were no significant differences between the EA group and the drug group (all P>0.05). Conclusion: EA can alleviate the inflammatory response of RA rats, improve their pathological conditions, reduce the expressions of phospho-JAK2 and phospho-STAT3 in the synovial tissue of knee joint, and decrease the expressions of JAK2 and STAT3 mRNAs. The therapeutic effect of EA is comparable to that of the tripterygium glycosides. The mechanism of EA treatment may be related to the inactivation of the JAK2/STAT3 pathway.

Elevated Levels of Soluble ST2 were Associated with Rheumatoid Arthritis Disease Activity and Ameliorated Inflammation in Synovial Fibroblasts

Background：Much evidence has demonstrated that interleukin （IL）-33 plays an important role in rheumatoid arthritis （RA）.However,there have been limited studies about soluble ST2,a receptor for 1L-33,in RA.The aims of this study were to detect the levels of ST2 in the serum and synovial fluid of RA patients and to reveal the association of these levels with disease activity and the function of ST2 in RA.Methods：A total of 56 RA patients and 38 age-matched healthy controls were enrolled in this study.Synovial fluid samples were collected from another 30 RA patients and 20 osteoartbritis patients.Serum and synovial fluid levels of ST2 were measured by ELISA.In addition,the levels of ST2 in the serum of RA patients before and after therapy were detected.The function of ST2 in RA was revealed by the results of an in vitro cell assay,where recombinant ST2 proteins were used to treat peripheral blood mononuclear cells （PBMCs） and RA synovial fibroblasts （RASFs）.Results：Serum-soluble ST2 levels were significantly higher in RA patients （127.14 ± 61.43 pg/ml） than those in healthy controls （78.37 ± 41.93 pg/ml,P 〈 0.01）.Synovial fluid-soluble ST2 levels （41.90 ± 33.58 pg/ml） were much higher in RA patients than those in osteoarthritis patients （19.71 ± 16.72 pg/ml,P 〈 0.05）.RA patients who received effective therapy for 6 months showed decreased serum-soluble ST2 levels （113.01 ± 53.90 pg/ml） compared to baseline （139.59 ± 68.36 pg/ml） （P =0.01）.RA patients with high disease activity had higher serum-soluble ST2 levels （162.02 ± 56.78 pg/ml） than those with low disease activity （94.67 ± 40.27 pg/ml,P =0.001）.Soluble ST2 did not affect IL-1β,IL-6,IL-8,or tumor necrosis factor-α （TNF-o） expression in PBMCs from RA patients.However,soluble ST2 ameliorated the expressions of IL-33 and IL-1 β but not that of IL-6,IL-8,or TNF-α in resting RASFs.Interestingly,in the RASFs stimulated by TNF-α plus IL-1 β,soluble ST2 showed extensive suppressive effects on the expression of IL-6,IL-8,and TNF-α.Conclusion：Elevated levels of ST2 in the serum and synovial fluid were associated with disease activity and ameliorated IL-33 expression and IL-33-induced inflammation in RASFs,suggesting that soluble ST2 might be a potential therapeutic candidate for RA.