Regulation of RAW264.7 macrophage polarization on smooth and rough surface topographies by galectin-3

Shikonin reduces M2 macrophage population in ovarian cancer by repressing exosome production and the exosomal galectin 3-mediated β-catenin activation

BACKGROUND

Shikonin (SK), a naphthoquinone with anti-tumor effects, has been found to decrease production of tumor-associated exosomes (exo). This study aims to verify the treatment effect of SK on ovarian cancer (OC) cells, especially on the production of exo and their subsequent effect on macrophage polarization.

METHODS

OC cells SKOV3 and A2780 were treated with SK. The exo were isolated from OC cells with or without SK treatment, termed OC exo and SK OC exo, respectively. These exo were used to treat PMA-induced THP-1 cells (M0 macrophages). M2 polarization of macrophages was determined by measuring the M2 specific cell surface markers CD163 and CD206 as well as the secretion of M2 cytokine IL-10. The functions of galectin 3 (LGALS3/GAL3) and β-catenin in macrophage polarization were determined by gain- or loss-of-function assays. CB-17 SCID mice were subcutaneously injected with SKOV3 cells to generate xenograft tumors, followed by OC exo or SK OC exo treatment for in vivo experiments.

RESULTS

SK suppressed viability, migration and invasion, and apoptosis resistance of OC cells in vitro. Compared to OC exo, SK OC exo reduced the M2 polarization of macrophages. Regarding the mechanism, SK reduced exo production in cancer cells, and it decreased the protein level of GAL3 in exo and recipient macrophages, leading to decreased β-catenin activation. M2 polarization of macrophages was restored by LGALS3 overexpression but decreased again by the β-catenin inhibitor FH535. Compared to OC exo, the SK OC exo treatment reduced the xenograft tumor growth in mice, and it decreased the M2 macrophage infiltration within tumor tissues.

CONCLUSION

This study suggests that SK reduces M2 macrophage population in OC by repressing exo production and blocking exosomal GAL3-mediated β-catenin activation.

A Glutathione Peroxidase-Mimicking Nanozyme Precisely Alleviates Reactive Oxygen Species and Promotes Periodontal Bone Regeneration

The use of oxidoreductase nanozymes to regulate reactive oxygen species (ROS) has gradually emerged in periodontology treatments. However, current nanozymes for treating periodontitis eliminate ROS extensively and non-specifically, ignoring the physiological functions of ROS under normal conditions, which may result in uncontrolled side effects. Herein, using the MIL-47(V)-F (MVF) nanozyme, which mimics the function of glutathione peroxidase (GPx), it is proposed that ROS can be properly regulated by specifically eliminating H2 O2 , the most prominent ROS. Through H2 O2 elimination, MVF contributes to limiting inflammation, regulating immune microenvironment, and promoting periodontal regeneration. Moreover, MVF stimulates osteogenic differentiation of periodontal stem cells directly, further promoting regeneration due to the vanadium in MVF. Mechanistically, MVF regulates ROS by activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) pathway and promotes osteogenic differentiation directly through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway. A promising periodontitis therapy strategy is presented using GPx-mimicking nanozymes through their triple effects of antioxidation, immunomodulation, and bone remodeling regulation, making nanozymes an excellent tool for developing precision medicine.

Myricetin induces M2 macrophage polarization to alleviate renal tubulointerstitial fibrosis in diabetic nephropathy via PI3K/Akt pathway

BACKGROUND

Development of end-stage renal disease is predominantly attributed to diabetic nephropathy (DN). Previous studies have indicated that myricetin possesses the potential to mitigate the pathological alterations observed in renal tissue. Nevertheless, the precise molecular mechanism through which myricetin influences the progression of DN remains uncertain.

AIM

To investigate the effects of myricetin on DN and explore its potential therapeutic mechanism.

METHODS

Db/db mice were administered myricetin intragastrically on a daily basis at doses of 50 mg/kg or 100 mg/kg for a duration of 12 wk. Subsequently, blood and urine indexes were assessed, along with examination of renal tissue pathology. Kidney morphology and fibrosis were evaluated using various staining techniques including hematoxylin and eosin, periodic acid-Schiff, Masson's trichrome, and Sirius-red. Additionally, high-glucose culturing was conducted on the RAW 264.7 cell line, treated with 25 mM myricetin or co-administered with the PI3K/Akt inhibitor LY294002 for a period of 24 h. In both in vivo and in vitro settings, quantification of inflammation factor levels was conducted using western blotting, real-time qPCR and ELISA.

RESULTS

In db/db mice, administration of myricetin led to a mitigating effect on DN-induced renal dysfunction and fibrosis. Notably, we observed a significant reduction in expressions of the kidney injury markers kidney injury molecule-1 and neutrophil gelatinase associated lipocalin, along with a decrease in expressions of inflammatory cytokine-related factors. Furthermore, myricetin treatment effectively inhibited the up-regulation of tumor necrosis factor-alpha, interleukin-6, and interluekin-1β induced by high glucose in RAW 264.7 cells. Additionally, myricetin modulated the M1-type polarization of the RAW 264.7 cells. Molecular docking and bioinformatic analyses revealed Akt as the target of myricetin. The protective effect of myricetin was nullified upon blocking the polarization of RAW 264.7 via inhibition of PI3K/Akt activation using LY294002.

CONCLUSION

This study demonstrated that myricetin effectively mitigates kidney injury in DN mice through the regulation of macrophage polarization via the PI3K/Akt signaling pathway.

Mac-2 binding protein glycosylation isomer, the FIB-4 index, and a combination of the two as predictors of non-alcoholic steatohepatitis

Approximately 10% non-alcoholic fatty liver disease (NAFLD) cases progress to non-alcoholic steatohepatitis (NASH). Liver biopsy, the gold standard for diagnosing NASH and associated liver fibrosis, is invasive with a risk of life-threatening complications. Therefore, reliable non-invasive biomarkers for predicting NASH are required to prevent unnecessary liver biopsies. We evaluated the performance of two non-invasive fibrosis markers, Mac-2 binding protein glycosylation isomer (M2BPGi) and the FIB-4 index for predicting the fibrosis staging, NAFLD activity scoring (NAS) index, and NASH. We also analyzed the correlation between the two markers. The sensitivities, specificities, positive predictive values (PPV), and negative predictive values of the FIB-4 index, M2BPGi, and a combination of both markers for NASH diagnosis were evaluated. The M2BPGi and FIB-4 index showed a good performance in diagnosing NASH, the fibrosis stage, and the NAS index in NAFLD patients. While both markers were well-correlated with each other in most cases, no correlation was found in some patients. Compared with the FIB-4 index or the M2BPGi alone, a combination of the two showed a higher specificity, PPV, and accuracy for NASH diagnosis. The M2BPGi and the FIB-4 index are easily accessible and reliable liver fibrosis markers. Diseases other than liver disease may cause dissociation between the two markers, causing failure to predict NASH. However, the combination of both markers can compensate for their disadvantages. Because the PPV of the combination was relatively high, patients who test positive for both markers should undergo liver biopsy for NASH diagnosis.

Titanium Implant Surface Effects on Adherent Macrophage Phenotype: A Systematic Review

Immunomodulatory biomaterials have the potential to stimulate an immune response able to promote constructive and functional tissue remodeling responses as opposed to persistent inflammation and scar tissue formation. As such, the controlled activation of macrophages and modulation of their phenotype through implant surface modification has emerged as a key therapeutic strategy.

METHODS

Online databases were searched for in vitro studies between January 1991 and June 2020 which examined the effect of titanium implant surface topography on the adherent macrophage phenotype at either the gene or protein level.

RESULTS

Thirty-nine studies were subsequently included for review. Although there was significant heterogeneity between studies, treatment of titanium surfaces increased the surface roughness or hydrophilicity, and hence increased macrophage attachment but decreased cell spreading. Physical coating of the titanium surface also tended to promote the formation of cell clusters. Titanium and titanium-zirconium alloy with a micro- or nano-scale rough topography combined with a hydrophilic surface chemistry were the most effective surfaces for inducing an anti-inflammatory phenotype in adherent macrophages, as indicated by significant changes in cytokine gene expression and or cytokine secretion profiles.

CONCLUSIONS

The published data support the hypothesis that incorporation of specific topographical and physiochemical surface modifications to titanium can modulate the phenotypic response of adherent macrophages.

Engineering Nanopatterned Structures to Orchestrate Macrophage Phenotype by Cell Shape

Physical features on the biomaterial surface are known to affect macrophage cell shape and phenotype, providing opportunities for the design of novel “immune-instructive” topographies to modulate foreign body response. The work presented here employed nanopatterned polydimethylsiloxane substrates with well-characterized nanopillars and nanopits to assess RAW264.7 macrophage response to feature size. Macrophages responded to the small nanopillars (SNPLs) substrates (450 nm in diameter with average 300 nm edge-edge spacing), resulting in larger and well-spread cell morphology. Increasing interpillar distance to 800 nm in the large nanopillars (LNPLs) led to macrophages exhibiting morphologies similar to being cultured on the flat control. Macrophages responded to the nanopits (NPTs with 150 nm deep and average 800 nm edge-edge spacing) by a significant increase in cell elongation. Elongation and well-spread cell shape led to expression of anti-inflammatory/pro-healing (M2) phenotypic markers and downregulated expression of inflammatory cytokines. SNPLs and NPTs with high availability of integrin binding region of fibronectin facilitated integrin β1 expression and thus stored focal adhesion formation. Increased integrin β1 expression in macrophages on the SNPLs and NTPs was required for activation of the PI3K/Akt pathway, which promoted macrophage cell spreading and negatively regulated NF-κB activation as evidenced by similar globular cell shape and higher level of NF-κB expression after PI3K blockade. These observations suggested that alterations in macrophage cell shape from surface nanotopographies may provide vital cues to orchestrate macrophage phenotype.

Possible important roles of galectins in the healing of human fetal membranes

The fetal membranes healing is a complex and dynamic process of replacing devitalized and missing cellular structures and tissue layers. Multiple cells and extracellular matrices, and cell differentiation, migration and proliferation may participate in restoring the integrity of damaged tissue, however this process still remains unclear. Therefore, there is a need to identify and integrate new ideas and methods to design a more effective dressing to accelerate fetal membrane healing. This review explores the function and role of galectins in the inflammatory, epithelial mesenchymal transition, proliferative migration, and remodeling phases of fetal membrane healing. In conclusion, the preliminary findings are promising. Research on amnion regeneration is expected to provide insight into potential treatment strategies for premature rupture of membranes.

Macrophage polarization plays roles in bone formation instructed by calcium phosphate ceramics

To investigate the roles of macrophages in material-instructed bone formation, two calcium phosphate (TCP) ceramics with the same chemistry but various scales of surface topography were employed in this study. After being implanted subcutaneously in FVB mice for 8 weeks, TCPs (TCP ceramics with submicron surface topography) gave rise to bone formation, while TCPb (TCP ceramics with micron surface topography) did not, showing the crucial role of surface topography scale in material-instructed bone formation. Depletion of macrophages with liposomal clodronate (LipClod) blocked such bone formation instructed by TCPs, confirming the role of macrophages in material-instructed bone formation. Macrophage cells (i.e. RAW 264.7 cells) cultured on TCPs in vitro polarized to tissue repair macrophages as evidenced by gene expression and cytokine production, while polarizing to pro-inflammatory macrophages on TCPb. Submicron surface topography of TCP ceramics directed macrophage polarization via PI3K/AKT pathways with the synergistic regulation of integrin β1. Finally, the tissue repair macrophage polarization on TCPs resulted in osteogenic differentiation of mesenchymal stem cells in vitro. At early implantation in FVB mice, TCPs recruited more macrophages which polarized towards tissue repair macrophages with time. The present data demonstrate the important roles of macrophage polarization in bone formation instructed by calcium phosphate ceramics.

Loganin alleviates macrophage infiltration and activation by inhibiting the MCP-1/CCR2 axis in diabetic nephropathy

BACKGROUND/AIMS

The theory of inflammation is one of the important theories in the pathogenesis of diabetic nephropathy (DN). We herein aimed to explore whether loganin affected macrophage infiltration and activation upon diabetic nephropathy (DN) by a spontaneous DN mice and a co-culture system of glomerular mesangial cells (GMCs) and macrophage cells (RAW264.7) which was induced by advanced glycation end products (AGEs).

METHODS AND KEY FINDINGS

Loganin showed remarkable capacity on protecting renal from damage by mitigating diabetic symptoms, improving the histomorphology of the kidney, decreasing the expression of extracellular matrix such as FN, COL-IV and TGF-β, reversing the production of IL-12 and IL-10 and decreasing the number of infiltrating macrophages in the kidney. Moreover, loganin showed markedly effects by suppressing iNOS and CD16/32 expressions (M1 markers), increasing Arg-1 and CD206 expressions (M2 markers), which were the phenotypic transformation of macrophage. These effects may be attributed to the inhibition of the receptor for AGEs (RAGE) /monocyte chemotactic protein-1 (MCP-1)/CC chemokine receptor 2 (CCR2) signaling pathway, with significantly down-regulated expressions of RAGE, MCP-1 and CCR2 by loganin. Loganin further decreased MCP-1 secretion when RAGE was silenced, which means other target was involved in regulating the MCP-1 expression. While loganin combinated with the inhibitor of CCR2 exerted stronger anti-inhibition effects of iNOS expression, suggesting that CCR2 was the target of loganin in regulating the activation of macrophages.

SIGNIFICANCE

Loganin could ameliorate DN kidney damage by inhibiting macrophage infiltration and activation via the MCP-1/CCR2 signaling pathway in DN.

Macrophage M1/M2 polarization

Macrophages can be affected by a variety of factors to change their phenotype and thus affect their function. Activated macrophages are usually divided into two categories, M1-like macrophages and M2-like macrophages. Both M1 macrophages and M2 macrophages are closely related to inflammatory responses, among which M1 macrophages are mainly involved in pro-inflammatory responses and M2 macrophages are mainly involved in anti-inflammatory responses. Improving the inflammatory environment by modulating the activation state of macrophages is an effective method for the treatment of diseases. In this review, we analyzed the mechanism of macrophage polarization from the tumor microenvironment, nanocarriers, nuclear receptor PPARγ, phagocytosis, NF-κB signaling pathways, and other pathways.

Integrin-associated molecules and signalling cross talking in osteoclast cytoskeleton regulation

In the ageing skeleton, the balance of bone reconstruction could commonly be broken by the increasing of bone resorption and decreasing of bone formation. Consequently, the bone resorption gradually occupies a dominant status. During this imbalance process, osteoclast is unique cell linage act the bone resorptive biological activity, which is a highly differentiated ultimate cell derived from monocyte/macrophage. The erosive function of osteoclasts is that they have to adhere the bone matrix and migrate along it, in which adhesive cytoskeleton recombination of osteoclast is essential. In that, the podosome is a membrane binding microdomain organelle, based on dynamic actin, which forms a cytoskeleton superstructure connected with the plasma membrane. Otherwise, as the main adhesive protein, integrin regulates the formation of podosome and cytoskeleton, which collaborates with the various molecules including: c-Cbl, p130^Cas , c-Src and Pyk2, through several signalling cascades cross talking, including: M-CSF and RANKL. In our current study, we discuss the role of integrin and associated molecules in osteoclastogenesis cytoskeletal, especially podosomes, regulation and relevant signalling cascades cross talking.

Usefulness of serum Mac-2 binding protein glycosylation isomer in patients undergoing hepatectomy: A case controlled study

Background

To evaluate the clinical significance of Mac-2 binding protein glycosylation isomer (M2BPGi), we investigated the relationship between M2BPGi and clinicopathological and surgical parameters and posthepatectomy complications.

Materials and methods

We examined M2BPGi in 115 patients with hepatic malignancies undergoing hepatectomy. Significance as an independent prognostic marker was determined with multivariate logistic regression analysis.

Results

The mean serum M2BPGi level was 1.14 ± 1.03 C.O.I. (range 0.2–5.79). M2BPGi in the chronic viral hepatitis group (1.42 ± 1.25) was significantly higher than that in the other disease groups (p < 0.05). The M2BPGi level correlated negatively with platelet count, LHL15 and GSA-Rmax (r = −0.36, −0.69 and −0.56, respectively; p < 0.01) but correlated positively with serum hyaluronate level (fibrotic marker), ICGR15 and HH15 (r = 0.52, 0.63 and 0.57, respectively; p < 0.01). In 53 patients examined for histological hepatic fibrosis, the M2BPGi level was highest for hepatic fibrosis stage 4, indicating cirrhosis (2.15 ± 1.56), and was significantly higher than that for stages 0–2 (p < 0.05). M2BPGi level did not correlate significantly with any surgical parameters. The preoperative level correlated significantly only with increased alanine aminotransferase level (r = −0.21, p < 0.05) and was significantly higher in patients with (1.35 ± 0.78) than without (1.11 ± 1.07) hepatectomy-related complications (p < 0.05). Area under the ROC curve analysis for prediction of hepatic fibrosis score 4 showed a cut-off value of 0.78 for M2BPGi to have high sensitivity (90%) and specificity (58%). For postoperative hepatectomy-related complications, only the M2BPGi level (at a cut-off value 0.90) tended to show significance (p = 0.06).

Conclusions

The non-invasively measured serum level of M2BPGi reflected impaired liver function or cirrhosis and hepatectomy-related complications after surgery, making it potentially useful as a complementary parameter accompanying other liver function parameters.

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The M2BPGi level was higher in patients with posthepatectomy complications.

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The M2BPGi level correlated negatively with the platelet count, LHL 15 and GSA-Rmax by liver scintigraphy.

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The M2BPGi level was highest in the patients with hepatic fibrosis.

Modulating macrophage polarization on titanium implant surface by poly(dopamine)-assisted immobilization of IL4

BACKGROUND

In the past few decades, very little research has been carried out to modify implant surfaces to improve osteointegration through the regulation of immune cells.

PURPOSE

The aim of this study is to investigate whether the poly(dopamine) (pDA)-assisted immobilization of IL4 on titanium surfaces could modulate the inflammatory profile of macrophages in vitro and search for the possibility of enhancing implant integration in this way.

MATERIAL AND METHODS

The surface composition, topography, and roughness of SLA, SLA-pDA, and SLA-pDA-IL4 discs were examined by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Then the releasing profile of the SLA-pDA-IL4 implants was recorded for 1 week and the bioactivity of released IL4 was investigated by ELISA. Then macrophage polarization was investigated via three methods including: (a) surface marker via immunofluorescence; (b) mRNA levels of M1 and M2 polarization markers via real-time PCR, and (c) cytokine release via ELISA.

RESULTS

SEM and EDS revealed that pDA and IL4 were coated successfully on SLA surfaces. The ELISA results showed that IL4 remained its bioactivity on SLA surface and were immobilized on the SLA surface. The immobilization of IL4 through pDA has no significant influence on the attachment, morphology, and proliferation of macrophages, while it increased the M2/M1 proportion in human macrophages revealed by immunofluorescence. The real-time PCR and ELISA results demonstrated that SLA-pDA-IL4 surface reduced the pro-inflammatory profile compared with SLA-pDA and SLA surfaces.

CONCLUSIONS

The SLA-pDA-IL4 surfaces described here is able to activate adherent macrophages into M2 phenotype and reduce the release of pro-inflammatory cytokines. Immobilization of IL4 via pDA is convenient and effective, thus providing an applicable way to control macrophage behavior upon implant insertion and is anticipated to accelerating further bone integration.

Nanostructural Surfaces with Different Elastic Moduli Regulate the Immune Response by Stretching Macrophages

A proper immune response is key for the successful implantation of biomaterials, and designing and fabricating biomaterials to regulate immune responses is the future trend. In this work, three different nanostructures were constructed on the surface of titanium using a hydrothermal method, and through a series of in vitro and in vivo experiments, we found that the aspect ratio of nanostructures can affect the elastic modulus of a material surface and further regulate immune cell behaviors. This work demonstrates that nanostructures with a higher aspect ratio can endow a material surface with a lower elastic modulus, which was confirmed by experiments and theoretical analyses. The deflection of nanostructures under the cell adsorption force is a substantial factor in stretching macrophages to enhance cell adhesion and spreading, further inducing macrophage polarization toward the M1 phenotype and leading to intense immune responses. In contrast, a nanostructure with a lower aspect ratio on a material surface leads to a higher surface elastic modulus, making deflection of the material difficult and creating a surface that is not conducive to macrophage adhesion and spreading, thus reducing the immune response. Moreover, molecular biology experiments indicated that regulation of the immune response by the elastic modulus is primarily related to the NF-κB signaling pathway. These findings suggest that the immune response can be regulated by constructing nanostructural surfaces with the proper elastic modulus through their influence on cell adhesion and spreading, which provides new insights into the surface design of biomaterials.

Paeoniflorin Ameliorates Macrophage Infiltration and Activation by Inhibiting the TLR4 Signaling Pathway in Diabetic Nephropathy

Paeoniflorin (PF) is the primary component of total glucosides of paeony (TGP). It exerts multiple effects, including immunoregulatory and anti-inflammatory effects. Our previous study has found that PF has a remarkable renal-protective effect in diabetic mice, but exact mechanism has not been clarified. This study mainly explores whether PF affects macrophage infiltration and activation in diabetic kidney through TLR4 pathway. Thus, this study was conducted to investigate the effect of PF on a streptozotocin (STZ)-induced experimental DN model. The results suggested that the onset and clinical symptoms of DN in mice were remarkably ameliorated after the administration of PF. Moreover, the number of infiltrating macrophages in the mouse kidneys was also markedly decreased. Instead of inhibiting the activation of macrophages directly, PF could influence macrophages by suppressing iNOS expression as well as the production of TNF-α, IL-1β, and MCP-1 both in vivo and in vitro. These effects might be attributable to the inhibition of the TLR4 signaling pathway. The percentage of M1-phenotype cells as well as the mRNA levels of iNOS, TNF-α, IL-1β, and MCP-1 were downregulated when PF-treated polarized macrophages were cultured under conditions of high glucose (HG) levels. In addition, the expression of TLR4, along with that of downstream signaling molecule proteins, was also reduced. Our study has provided new insights into the potential of PF as a promising therapeutic agent for treating DN and has illustrated the underlying mechanism of PF from a new perspective.

Galectin-3 exacerbates ox-LDL-mediated endothelial injury by inducing inflammation via integrin β1-RhoA-JNK signaling activation

Oxidized low‐density lipoprotein (Ox‐LDL)‐induced endothelial cell injury plays a crucial role in the pathogenesis of atherosclerosis (AS). Plasma galectin‐3 (Gal‐3) is elevated inside and drives diverse systemic inflammatory disorders, including cardiovascular diseases. However, the exact role of Gal‐3 in ox‐LDL‐mediated endothelial injury remains unclear. This study explores the effects of Gal‐3 on ox‐LDL‐induced endothelial dysfunction and the underlying molecular mechanisms. In this study, Gal‐3, integrin β1, and GTP‐RhoA in the blood and plaques of AS patients were examined by ELISA and western blot respectively. Their levels were found to be obviously upregulated compared with non‐AS control group. CCK8 assay and flow cytometry analysis showed that Gal‐3 significantly decreased cell viability and promoted apoptosis in ox‐LDL‐treated human umbilical vascular endothelial cells (HUVECs). The upregulation of integrinβ1, GTP‐RhoA, p‐JNK, p‐p65, p‐IKKα, and p‐IKKβ induced by ox‐LDL was further enhanced by treatment with Gal‐3. Pretreatment with Gal‐3 increased expression of inflammatory factors (interleukin [IL]‐6, IL‐8, and IL‐1β), chemokines(CXCL‐1 and CCL‐2) and adhesion molecules (VCAM‐1 and ICAM‐1). Furthermore, the promotional effects of Gal‐3 on NF‐κB activation and inflammatory factors in ox‐LDL‐treated HUVECs were reversed by the treatments with integrinβ1‐siRNA or the JNK inhibitor. We also found that integrinβ1‐siRNA decreased the protein expression of GTP‐RhoA and p‐JNK, while RhoA inhibitor partially reduced the upregulated expression of p‐JNK induced by Gal‐3. In conclusion, our finding suggests that Gal‐3 exacerbates ox‐LDL‐mediated endothelial injury by inducing inflammation via integrin β1‐RhoA‐JNK signaling activation.

Mac-2 binding protein glycan isomer (M2BPGi) is a new serum biomarker for assessing liver fibrosis: more than a biomarker of liver fibrosis

Assessing liver fibrosis is important for predicting the efficacy of antiviral therapy and patient prognosis. Liver biopsy is the gold standard for diagnosing liver fibrosis, despite its invasiveness and problematic diagnostic accuracy. Although noninvasive techniques to assess liver fibrosis are becoming important, reliable serum surrogate markers are not available. A glycoproteomics study aimed at identifying such markers discovered Mac 2-Binding Protein Gylcan Isomer (M2BPGi), which is a reliable marker for assessing liver fibrosis in patients with viral hepatitis and other fibrotic liver diseases such as primary biliary cholangitis, biliary atresia, autoimmune hepatitis, and nonalcoholic fatty liver disease. M2BPGi predicts the development of hepatocellular carcinoma (HCC) in patients infected with hepatitis B and C as well as the prognosis of liver cirrhosis in those with HCC after therapy. The unique features of M2BPGi are as follows: (1) cut-off values differ for the same stages of fibrosis according to the cause of fibrosis; and (2) M2BPGi levels rapidly decrease after patients achieve a sustained antiviral response to hepatitis C virus. These observations cannot be explained if M2BPGi levels reflect the amount of fibrotic tissue. Hepatic stellate cells (HSCs) secrete M2BPGi, which may serve as a messenger between HSCs and Kupffer cells via Mac-2 (galectin 3) that is expressed in Kupffer cells during fibrosis progression. Here we show that M2BPGi is a surrogate marker for assessing HSC activation. These findings may reveal the roles of HSCs in extrahepatic fibrotic disease progression.

Galectin-3 is essential for proper bone cell differentiation and activity, bone remodeling and biomechanical competence in mice

OBJECTIVE

Galectin-3 is constitutively expressed in bone cells and was recently shown to modulate osteogenic transdifferentiation of vascular smooth muscle cells and atherosclerotic calcification. However, the role of galectin-3 in bone physiology is largely undefined. To address this issue, we analyzed (1) the skeletal features of 1-, 3- and 6-month-old galectin-3 null (Lgals3^-/-) and wild type (WT) mice and (2) the differentiation and function of osteoblasts and osteoclasts derived from these animals.

METHODS

Long bone phenotype, gene expression profile, and remodeling were investigated by micro-computed tomography, real time-PCR, static and dynamic histomorphometry, and assessment of biochemical markers of bone resorption and formation. Bone competence was also evaluated by biomechanical testing at 3 months. In vitro, the effects of galectin-3 deficiency on bone cell differentiation and function were investigated by assessing (a) gene expression of osteoblast markers, alkaline phosphatase activity, mineralization assay, and WNT/β-catenin signaling (of which galectin-3 is a known regulator) in osteoblasts; and (b) tartrate-resistant acid phosphatase activity and bone resorption activity in osteoclasts.

RESULTS

Lgals3^-/- mice revealed a wide range of age-dependent alterations including lower bone formation and higher bone resorption, accelerated age-dependent trabecular bone loss (p < 0.01 vs. WT at 3 months) and reduced bone strength (p < 0.01 vs. WT at 3 months). These abnormalities were accompanied by a steady inflammatory state, as revealed by higher bone expression of the pro-inflammatory cytokines interleukin (IL)-1β and IL-6 (p < 0.001 vs. WT at 3 months), increased content of osteal macrophages (p < 0.01 vs. WT at 3 months), and reduced expression of markers of alternative (M2) macrophage activation. Lgals3^-/- osteoblasts and osteoclasts showed impaired terminal differentiation, reduced mineralization capacity (p < 0.01 vs. WT cells) and resorption activity (p < 0.01 vs. WT cells). Mechanistically, impaired differentiation and function of Lgals3^-/- osteoblasts was associated with altered WNT/β-catenin signaling (p < 0.01 vs. WT cells).

CONCLUSIONS

These data provide evidence for a contribution of galectin-3 to bone cell maturation and function, bone remodeling, and biomechanical competence, thus identifying galectin-3 as a promising therapeutic target for age-related disorders of bone remodeling.

Substrate stiffness influences phenotype and function of human antigen-presenting dendritic cells

Dendritic cells (DCs) are specialized immune cells that scan peripheral tissues for foreign material or aberrant cells and, upon recognition of such danger signals, travel to lymph nodes to activate T cells and evoke an immune response. For this, DCs travel large distances through the body, encountering a variety of microenvironments with different mechanical properties such as tissue stiffness. While immune-related pathological conditions such as fibrosis or cancer are associated with tissue stiffening, the role of tissue stiffness in regulating key functions of DCs has not been studied yet. Here, we investigated the effect of substrate stiffness on the phenotype and function of DCs by conditioning DCs on polyacrylamide substrates of 2, 12 and 50 kPa. Interestingly, we found that C-type lectin expression on immature DCs (iDCs) is regulated by substrate stiffness, resulting in differential antigen internalization. Furthermore, we show that substrate stiffness affects β2 integrin expression and podosome formation by iDCs. Finally, we demonstrate that substrate stiffness influences CD83 and CCR7 expression on mature DCs, the latter leading to altered chemokine-directed migration. Together, our results indicate that DC phenotype and function are affected by substrate stiffness, suggesting that tissue stiffness is an important determinant for modulating immune responses.